JP2006267235A - Heating member and image heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating member which has a heat-resistant layer whose surface is externally heated by a heating means, and which is brought into contact with a material to be heated, thereby heating an unfixed image on the material, the heating member being designed so as to obtain stable fixing performance by achieving excellent performance in all aspects such as shortening the warm-up time or first print out time of an image heating device, reducing power consumption, increasing the speed, enhancing image quality and prolonging its life time, and also to provide the image heating device that has the heating member. <P>SOLUTION: The heat resistant layer 22b of the heating member 22 is formed by baking or hardening a compound formed by admixing hollow filler with an organo polysiloxane composition or by admixing a water-absorbent polymer or water with the organo polysiloxane composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heating member that contacts an object to be heated and heats an image on the object to be heated, and an image heating apparatus including the heating member. It is suitable for use in an image forming apparatus employing an image forming process.

  2. Description of the Related Art Conventionally, in a heat fixing apparatus as an image heating apparatus provided in an image forming apparatus adopting an electrophotographic method or an electrostatic recording method, a recording material as a heated material carrying an unfixed toner image as an image (Transfer material sheet, printing paper, electrostatic recording paper, electrofax paper, etc.) are formed by a heating roller (fixing roller) as a heating member that rotates in pressure contact with each other and a pressure roller as a pressure member. 2. Description of the Related Art A so-called heat roller type heat fixing device is widely used that fixes a recording material as a permanent image by passing through a pressure nip (fixing nip).

  FIG. 11 shows a schematic configuration of the heat roller type heat fixing device.

  The fixing roller 50 is provided with a heating body 51 such as a halogen lamp inside a hollow cored bar 52 made of aluminum or stainless steel, and a release layer 53 made of a fluororesin or the like for preventing toner offset on the outer peripheral surface. It is a thing. The temperature of the peripheral surface of the fixing roller is detected by using a temperature detection means 54 such as a thermistor, and energization to the heating body 51 is controlled so that the temperature becomes constant. The pressure roller 60 is formed with an elastic layer made of silicon rubber or the like or a sponge elastic layer 62 formed by foaming silicon rubber on the outer periphery of a cored bar 61 made of aluminum, iron or the like, and further fixed on the outer layer. A releasable layer 63 such as a fluororesin similar to the roller 50 is formed. N is a fixing nip portion.

  Further, in the case of a high-speed image forming apparatus or a color image forming apparatus using color toner, in order to sufficiently satisfy the toner fixing property and prevent uneven fixing, the fixing roller 50 is separated from the hollow core metal 52. In some cases, an elastic layer having a thickness of about 2 mm, such as silicon rubber, is provided between the mold layers 53, and the unfixed toner image T on the recording material P is wrapped around the softened fixing roller peripheral surface so that the recording material and The efficiency of heat transfer to the toner is improved.

  As described above, in the conventional heat roller type heat fixing apparatus, the recording material P on which the unfixed toner image is formed is nipped and conveyed by the fixing roller 50 and the pressure roller 60 in the fixing nip portion N, and heat and pressure are applied to the recording material. Thus, the unfixed toner image was fixed on the recording material as a fixed image.

  In such a conventional heat roller type heat fixing device, in order to maintain the amount of heat applied to the unfixed toner image on the recording material for speeding up the image forming apparatus, a fixing roller and a pressure roller having a large outer diameter The fixing nip width in the recording material conveying direction is increased by selecting a large pressure and setting the pressure force, and the temperature control temperature of the fixing roller peripheral surface is increased.

  However, in order to withstand the high pressure applied between the fixing roller and the pressure roller in terms of strength, the core metal of the fixing roller and the pressure roller has to be increased in thickness and diameter.

  For this reason, the heat capacity of the fixing roller 50 is increased, and in the heating and fixing apparatus that heats from the inside of the fixing roller by the heating body 51, it takes time (hereinafter referred to as warm) to raise the temperature of the outer peripheral surface of the fixing roller 50 to a state where fixing is possible. It takes a long time from when the power switch of the image forming apparatus is turned on until the heat fixing device is ready for heat fixing. In particular, when an elastic layer is provided on the peripheral surface of the fixing roller, it takes more time to raise the peripheral surface temperature.

  Further, even in a standby state in which the image forming apparatus does not operate, it is necessary to preheat the fixing roller (hereinafter referred to as standby heating), which increases power consumption when the image forming apparatus is not used. The amount of power consumed during a certain period has also increased.

  On the other hand, while reduction of power consumption is strongly desired as one of the environmental problems in recent years, image output with high image quality and high speed is desired from market needs. Therefore, in order to meet such demands for reduction of power consumption and high speed and high image quality, various improvements have been attempted on the heat roller type heat fixing apparatus.

  First, for the purpose of shortening the heating time of the fixing roller and reducing the power consumption, a heating body 84 such as a halogen lamp is included in a curved reflecting plate 85 as shown in FIG. A fixing roller 80 having an elastic layer 82 formed of silicone rubber, foamed silicone rubber or the like is disposed on the outer surface of the hollow cored bar 81 so as to face the surface of the hollow cored bar 81, and the heating fixing device heats only the peripheral surface of the fixing roller 80 by the heating body 84 One example is proposed in Patent Documents 1 and 2.

  In the case of this heat fixing device, since the fixing roller 80 is heated from the outside, the peripheral surface of the fixing roller 80 can be rapidly heated, and the warm-up time is shortened compared with the heat roller fixing device shown in FIG.

  Further, the method of heating the fixing roller 80 from the outside is roughly classified into a contact type and a non-contact type as shown in FIG. 12, but the contact type is disclosed in Patent Document 3. As described above, a system in which a small-diameter heating roller is brought into contact with the peripheral surface of the fixing roller has been proposed.

  In the case of this heat fixing device, the heating roller of a small diameter is heated in a short time, and the heating speed of the peripheral surface of the fixing roller is increased in order to directly heat the peripheral surface of the fixing roller with the heating roller.

  In Patent Document 4, in order to suppress the heat capacity of the fixing member, a layer in which a heat insulating layer, an elastic layer, and a release layer are sequentially laminated is provided on the base of the fixing member, and a small-sized heating roller is externally provided on the surface of the fixing member. A method for heating the surface of the fixing member by bringing them into contact with each other is disclosed. That is, as shown in FIG. 13, the fixing member 90 has an endless fixing belt 92 as a heating member, a winding roller 93, and a tension roller 91, and the fixing belt 92 is wound around the winding roller 93 and the tension roller. A tension is applied to 91 and the surface is heated by a small-diameter heating roller 95 having a heater 94 inside from the outside of the fixing belt.

  The fixing belt 92 is formed by applying a foamed silicone rubber layer as a heat insulating layer to a polyimide resin belt base, a solid silicone rubber layer as an elastic layer thereon, and a fluororesin releasing layer on the surface. Since the low heat capacity fixing belt 92 is heated from the outside, the surface of the fixing belt can be rapidly heated, and the warm-up time is shortened. Further, since the fixing belt 92 has an elastic layer, it is possible to prevent the occurrence of uneven image gloss by the fixing belt uniformly contacting the unfixed toner image.

  On the other hand, in particular, a method in which power is not supplied to the heating and fixing device during standby, and standby heating is not performed. Specifically, a toner image on a recording material is transferred via a thin film having a small heat capacity between the heater unit and the pressure roller. An example of a heat fixing method using a film heating method for fixing is proposed in Patent Document 5.

  FIG. 14 shows a schematic configuration of an example of the film heating method.

  Reference numeral 70 denotes a film assembly. A heater (heating body) 71 in which an energized heating resistance layer is formed on a ceramic plate such as alumina or aluminum nitride is fixed to a stay holder 74 formed of a heat resistant resin. The holder 74 has a heat-resistant thin film 73 (hereinafter referred to as a fixing film) made of a resin such as polyimide or a metal such as SUS that is loosely fitted on the holder 74. The pressure roller 60 is in pressure contact with the heater 71 with the fixing film 73 in a close-contact sliding state interposed therebetween. The fixing film 73 is conveyed and moved in the direction of the arrow by the rotational force of the pressure roller 60 while closely contacting and sliding on the heater 71 at the fixing nip N. The temperature of the heater 71 is detected by temperature detection means 72 such as a thermistor disposed on the back surface of the heater, and is fed back to an energization control unit (not shown) to execute ON / OFF control of the heater 71 to be constant. Heating and temperature adjustment are performed so that the temperature (fixing temperature) is reached.

Various image forming apparatuses such as printers and copiers that use such a film heating type heat fixing device are not required for standby heating during standby and have a warm-up time due to their high heating efficiency and rapid startup. It has many advantages over the conventional heat roller type heat fixing device such as shortening.
JP-A-7-152271 Japanese Patent Laid-Open No. 9-54510 JP-A-10-133505 JP 2002-278338 A JP-A-4-204984

  However, even with the above-described conventional heating and fixing apparatus, it is very difficult to achieve excellent performance in all of the shortening of the temperature raising time at the time of startup, the reduction of power consumption, and the high speed and high image quality.

  For example, as shown in FIG. 12, when the surface of the fixing roller having an elastic layer is heated from the outside by a heat source such as a halogen heater, the warm-up time becomes longer if the heat capacity of the fixing roller is large, and it is necessary to perform standby heating. . For this reason, when a small-diameter fixing roller is configured to reduce the heat capacity of the fixing roller, it becomes difficult to secure a fixing nip width formed by the fixing roller and the pressure roller, and an unfixed image on the recording material is heated. Therefore, it is necessary to raise the surface temperature of the fixing roller to a higher level in order to compensate for this. Therefore, it has been difficult to shorten the warm-up time to such an extent that standby heating is unnecessary and to obtain sufficient fixing performance.

  Further, in the film heating apparatus shown in FIG. 14, when the speed is increased, image deterioration becomes remarkable. In particular, in a film heating device that rotates by driving a pressure roller, the speed of the film is delayed with respect to the speed of the pressure roller because the fixing film that is in direct contact with the unfixed toner image is driven and rotated by the rotation of the pressure roller This problem becomes larger as the speed increases. Since the recording material is conveyed by the pressure roller, the speed of the recording material is the same as that of the pressure roller. However, if the speed of the fixing film is slow, the unfixed toner image is rubbed by the film by this speed difference. Leading to degradation of image quality. This is because the film surface needs to emphasize releasability, so it is made of a material with good slipperiness such as a fluororesin layer, while the inner surface of the film also has good slipperiness due to sliding with the heater. If the slidability between the heater and the film is impaired due to durability, the film becomes difficult to rotate with respect to the rotational driving of the pressure roller. This occurs because the running speed of the car becomes slightly delayed. This phenomenon is particularly seen in halftone images and the like, resulting in an image in which the halftone uniformity is impaired.

  Furthermore, in the case of the film heating method shown in FIG. 11, the thickness of the film is formed as small as possible in order to eliminate the need for standby heating, and it has become difficult to obtain image fixing uniformity.

  As shown in FIG. 13, in the case of the method according to Patent Document 4 in which the fixing belt surface in contact with the unfixed toner image on the recording material is heated from the outside by a heating means, the warm-up time is reduced by suppressing the heat capacity of the fixing belt. Since the fixing belt has an elastic layer, the fixing uniformity of the image on the recording material can be ensured.

  However, in the case of the method described in Patent Document 4, the following problems have not been solved. That is, according to the contents described in Patent Document 4, foamed silicone rubber using low thermal conductivity is used for the heat insulating layer as one layer of the fixing belt, and the foamed silicone rubber is a pyrolytic foaming agent. And a method of forming a foam using hydrogen gas by-produced during curing as a foaming agent.

  However, the method of adding a pyrolytic foaming agent has been problematic in terms of the toxicity and odor of the decomposition gas, and in the case of using a platinum catalyst as the curing catalyst, there has been a problem of inhibition of curing by the blowing agent. Furthermore, the method using hydrogen gas produced as a by-product during curing has problems such as the explosive nature of hydrogen gas and the need to handle the uncured product during storage. In addition, there is a problem that it is difficult to obtain a foamed silicone rubber having fine and uniform cells in molding such as injection molding in a mold. Since it was difficult to form minute and uniform cells, the cell diameter in the foamed silicone rubber was easily formed non-uniformly, the cell wall thickness was also non-uniform, and the strength varied greatly. From this, it has been confirmed that when a fixing belt is formed, if a tension is continuously applied to the fixing belt with a small radius of curvature, the weak cell wall is broken and bubbles are broken.

  In addition, it has been difficult to achieve both durability and heat insulation with foamed silicone rubber. In other words, in the case of foamed silicone rubber having a non-uniform foam diameter, the cell wall constituting the elastic layer becomes thinner when the foaming ratio is increased in order to increase the heat insulation, and bubbles are more likely to break due to durability. It tends to occur.

  Further, as described in Patent Document 4, when the foamed silicone rubber is formed immediately below the releasable layer on the surface of the fixing belt, the temperature at the rubber portion and the bubble portion of the non-uniform foam is determined. It is suggested that unevenness occurs and this temperature unevenness appears as uneven glossiness of the image.

  For this reason, the configuration of the fixing belt described in Patent Document 4 is a configuration that eliminates temperature unevenness by forming a heat insulating layer such as foamed silicone rubber on the polyimide base layer and further forming an elastic layer of solid rubber on the outside thereof. It has become.

  From the above, it is necessary for the fixing belt as described in Patent Document 4 to keep the circumference of the fixing belt large to prevent foaming of the foamed silicone rubber, and the minimum curvature of the fixing belt is required. It was difficult to set the radius too small. Furthermore, it is necessary to form an elastic layer of silicone rubber between the releasable layer and the foamed silicone rubber, increasing the heat capacity. For this reason, as described in Patent Document 4, the rise time (corresponding to the warm-up time in this case) needs to be 40 seconds or more. This time of 40 seconds or more is a very long time to be employed in an image forming apparatus that does not perform standby heating, and is a time of 4 seconds to 10 seconds currently achieved by the film heating method shown in FIG. In the case of an apparatus that does not perform standby heating by the film heating method, it is not possible to ensure superiority with respect to the time corresponding to the warm-up time included in the first printout time. Therefore, when the method described in Patent Document 4 is employed in an image forming apparatus that does not perform standby heating, image formation is not performed for a while, and when the fixing device starts a printing operation from a state close to room temperature, This means that a print time of 40 seconds or more (hereinafter referred to as a first printout time) is required each time.

  In order to solve this problem, when standby heating is performed, it is necessary to heat the fixing belt while it is in standby. This is because the fixing belt is formed of only a member having low thermal conductivity such as polyimide, foamed silicone rubber, silicone rubber, and fluororesin, and the foamed silicone rubber layer forming one layer of the fixing belt has high heat insulation. Therefore, there is no means for transferring heat in the circumferential direction in response to heating from the outside of the fixing belt, and when the standby heating is performed without rotating the fixing belt, the circumferential direction of the fixing belt Even if a part of the belt is heated and the printing operation is started, it cannot be kept heated in the circumferential direction of the fixing belt other than the portion corresponding to the standby heating, and it takes a long time to warm up. Because it becomes. Further, in this case, there is a drawback that temperature unevenness in the circumferential direction of the fixing belt becomes large. Therefore, it is necessary to carry out standby heating while the fixing belt is rotated. As a result, the life of the fixing belt is shortened.

  As described above, the above-described conventional heat fixing apparatus that heats the surface of the fixing belt in contact with the unfixed toner image on the recording material from the outside by the heating means does not consume power during standby and receives a print signal. The first printout time until the recording material on which the unfixed toner image is formed is heat-fixed is sufficiently reduced, the speed of the image forming apparatus is increased, and the image including the halftone image is in a high quality state. There has not been realized a heat-fixing apparatus that achieves a long durability life and achieves a sufficient fixing performance for a recording material by heat-fixing.

  Accordingly, an object of the present invention is a heating member that has a heat insulating layer, the surface of which is heated from the outside by a heating unit, and that contacts an object to be heated to heat an image on the object to be heated. It is an object of the present invention to provide a heating member that achieves excellent performance in all of the reduction of uptime and first printout time, reduction of power consumption, high speed, high image quality, and long life, and stable fixing performance.

  Another object of the present invention is to provide an image heating apparatus including the heating member.

  The configuration of a representative heating member according to the present invention is a heating member that has a heat insulating layer, the surface is heated from the outside by a heating means, and contacts the heated material to heat the image on the heated material. The heat insulating layer is formed by firing and curing after forming a compound in which a hollow filler is blended with an organopolysiloxane composition, or a compound in which a water-absorbing polymer and water are blended in an organopolysiloxane composition. It is a heating member characterized by these.

  The configuration of a typical image heating apparatus according to the present invention includes a heating member having a heat insulating layer, a pressure member that presses the heating member to form a nip portion, and a heating unit that heats the surface of the heating member from the outside. In an image heating apparatus that heats an image on a material to be heated by sandwiching and conveying the material to be heated in a nip portion, the heat insulating layer of the heating member is a compound in which a hollow filler is blended with an organopolysiloxane composition Alternatively, the image heating apparatus is characterized in that it is formed by baking and curing after forming a blend of a water-absorbing polymer and water in an organopolysiloxane composition.

  According to the present invention, it is possible to achieve superior performance in all of the image heating device, such as shortening the warm-up time and first printout time, reducing power consumption, and further achieving high speed, high image quality, and long life, and stable fixing performance. Obtainable.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

(1) Example of Image Forming Apparatus FIG. 1 is an overall configuration diagram of an example of an image forming apparatus provided with a heat fixing device as an image heating device according to the present invention. The image forming apparatus of this embodiment is a laser beam printer using a transfer method and an electrophotographic process.

  The image forming apparatus shown in the present embodiment includes a sheet feeding apparatus having a feeding tray 1, a sheet stacking table 2, and a feeding roller 3 in an image forming apparatus main body A. The recording material P stacked on the sheet stacking table 2 in the feeding tray 1 is picked up one by one from the uppermost recording material by the feeding roller 3 and sent to the registration unit by the conveying roller 4 and the conveying roller 5. . The recording material P is fed to the image forming unit after the conveyance direction is aligned by the registration unit including the registration roller 6 and the registration roller 7.

  The image forming unit includes a process cartridge 9, a laser scanner unit 10 as an exposure unit, a transfer roller 14 as a transfer unit, and the like. The process cartridge 9 includes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 8 as an image carrier, a charger 11 as a charging unit, a developing unit 12 as a developing unit, and a cleaning unit. The cleaner 13 and the like are integrally formed as a unit, and are detachably attached to the image forming apparatus main body B. The laser scanner unit 10 is constituted by unitizing a polyhedral mirror, a polyhedral mirror rotating motor, a laser unit, and the like.

  The photosensitive drum 8 is rotationally driven in a clockwise direction indicated by an arrow at a predetermined peripheral speed (process speed). First, the outer peripheral surface is uniformly charged by the charger 11. Next, a laser beam La based on image information is irradiated from the laser scanner unit 10 to the charged surface, and a latent image based on the image information is formed on the uniformly charged surface of the photosensitive drum 8 by an electrophotographic method. . This latent image is developed upon receipt of toner from a developing roller of a developing device 12 containing toner as a developer. From the photosensitive drum surface side, the developed toner image is fed from the resist portion to the recording material P fed at a predetermined timing from the resist portion to the transfer portion which is the opposite portion of the photosensitive drum 8 and the transfer roller 14 at the position of the transfer roller 14. Electrostatic transfer.

  The recording material P that has received the transfer of the toner image from the surface of the photosensitive drum 8 in the transfer section is separated from the surface of the photosensitive drum and conveyed to the heat fixing device 15 as the image heating device according to the present invention. The image (unfixed image) is subjected to fixing processing. As a result, the unfixed toner image is heated and fixed on the recording material surface as a permanent image.

  The recording material P that has exited the heat fixing device 15 is discharged onto the discharge tray 17 by a discharge unit including an intermediate discharge roller 16a, a discharge roller 16b, and the like.

  On the other hand, the surface of the photosensitive drum 8 after separation of the recording material is cleaned by the cleaner 13 after removal of adhering contaminants such as transfer residual toner, and is repeatedly used for image formation.

  In addition, a cooling fan 18 is attached to the side surface of the image forming apparatus main body A, and the temperature increasing points such as the image forming unit and the electrical board are cooled by appropriately rotating the cooling fan and taking outside air into the apparatus. Further, a temperature detection means 19 such as a thermistor is attached in the vicinity of the cooling fan 18. When air outside the apparatus is taken in by the cooling fan 18, the temperature of the environment where the image forming apparatus is installed is detected by the temperature detection means 19, and is fed back to the temperature control sequence of the heat fixing apparatus 15 based on the detection result. To do.

(2) Heat Fixing Device FIG. 2 is a cross-sectional side view of the heat fixing device 15, FIG. 3 is a partially cutaway front model view of the heat fixing device, and FIG.

  As shown in FIGS. 2 and 3, the heat fixing device 15 includes a backup roller 21 and an elastic pressure roller (pressure member) as a pressure member with an endless thin heat insulating belt (heating rotator) 22 as a heat member interposed therebetween. (Hereinafter referred to as pressure rollers) 30 are arranged. Then, a non-contact type radiant heating source (halogen heater, carbon heater or the like) 24 as a heating means (heating source), and radiant heat from the radiant heating source 24 are directed to the surface of the heat insulating belt 22 outside the heat insulating belt 22. It has the reflecting member 25 to reflect.

  The backup roller 21 is formed in an elongated roller shape having a smaller diameter than the inner diameter of the heat insulating belt 22, and includes a core metal 21a and a central large-diameter core shaft portion 21b provided around the core metal 21a. The longitudinal ends of the cored bar 21a are rotatably supported by the front and back apparatus chassis side plates 18 and 19 via bearings 26.

  The pressure roller 30 is formed in an elongated roller shape having substantially the same length as the backup roller 21, a cored bar 31, and an elastic layer 32 provided as a pressurized central large-diameter core shaft around the cored bar 31, A release layer 33 covering the circumferential surface of the elastic layer 32. The pressure roller 30 is disposed in parallel with the backup roller 21 with the heat insulating belt 22 in between, and both longitudinal ends of the cored bar 31 are rotatable on the front and rear apparatus chassis side plates 18 and 19 via bearings 34. It is supported.

  The longitudinal both ends of the metal core 21a of the backup roller 21 are pressed against the pressure roller 30 by the pressure spring S, and the central large-diameter core shaft portion is brought into pressure contact with the inner surface of the heat insulating belt 22 by the central large-diameter core shaft portion 21b. A pressure nip portion K is formed between 21 b and the heat insulating belt 22. When the surface of the heat insulating belt 22 is pressed against the release layer 33 on the surface of the pressure roller 30 at the position of the pressure nip K, a fixing nip portion N having a predetermined width is formed between the heat insulating belt 22 and the pressure roller 30. Is forming. W is a conveyance nipping area (sheet passing area) of the recording material P in the fixing nip N.

  The radiant heating device 24 and the reflecting plate 25 are supported and fixed to the device chassis side plates 18 and 19, respectively.

  On the surface of the heat insulation belt 22, a temperature thermistor or the like is disposed as a temperature detection means 23 in contact or an infrared temperature detection sensor or the like is not in contact. The temperature detection means 23 uses the temperature detection information on the surface of the heat insulation belt 22 as a CPU. And output to a temperature control circuit 110 comprising a RAM or ROM memory.

  IG is a fixing entrance guide that guides the leading end of the recording material P that has received the transfer of the toner image from the surface of the photosensitive drum 8 to the fixing nip portion N in the transfer portion. OG is a fixing discharge guide that guides the leading end of the recording material P that has exited the fixing nip N to the discharging unit. The fixing inlet guide IG and the fixing discharge guide OG are each formed using heat-resistant grade PET, PBT, PPS, or the like.

  Below, the structure of the heat insulation belt 22, the backup roller 21, and the pressure roller 30 is demonstrated in detail.

(A) Heat Insulating Belt As shown in FIG. 4, the heat insulating belt 22 is made of a heat-resistant resin such as polyimide, polyamideimide, PEEK, PFA, PTFE, and FEP, or a thin flexible film formed from a metal such as SUS or Ni. An endless belt-like base layer 22a having a base material is used as a base material. As the base layer 22a, although it depends on the thermal conductivity and thickness of the heat insulating layer 22b described later, it is preferable to use a member having low thermal conductivity. A heat insulating layer 22b formed by the following method is formed outside the base layer 22a (on the fixing nip portion N side).

  The heat insulating layer 22b is a silicone rubber composition, and is a silicone rubber composition obtained by blending 0.1 to 200 parts by weight of a hollow filler having an average particle size of 500 μm or less with 100 parts by weight of a thermosetting organopolysiloxane composition. Is formed by heat curing (firing and curing). Here, as the hollow filler, there is a microballoon material or the like that reduces the thermal conductivity like sponge rubber by having a gas portion in the cured product. Such materials may be any of glass balloons, silica balloons, carbon balloons, phenol balloons, acrylonitrile balloons, vinylidene chloride balloons, alumina balloons, zirconia balloons, shirasu balloons and the like.

  Specific examples of the inorganic microballoons are listed below, but the hollow filler is not limited thereto. Shirasu balloons are Winlite manufactured by Idichi Kasei Co., Ltd., Sankilite manufactured by Sanki Kogyo Co., Ltd., and glass balloons are Caloon manufactured by Nippon Sheet Glass Co., Ltd., Cellstar manufactured by Asahi Glass Co., Ltd., 3M As glass bubbles fillers and silica balloons manufactured by Asahi Glass Co., Ltd., Q-CEL, as fly ash balloons, CERASPHERES manufactured by PFAMARKETING Co., Ltd., and as alumina balloons, manufactured by Showa Denko KK There is BW. Examples of the zirconia balloon include HOLLOW ZIRCONIUM SPHEES manufactured by ZIRCOA, and examples of the carbon balloon include clecas sphere manufactured by Kureha Chemical Co., Ltd. Among these, the hollow filler itself has elasticity, that is, a hollow balloon made of thermoplastic resin, particularly a polymer of vinylidene chloride, acrylonitrile, methacrylonitrile, acrylate ester, methacrylate ester, or two of them. What consists of the above copolymers etc. is suitable.

  Furthermore, examples of the thermally expandable microballoon material include Matsumoto Microsphere-F Series from Matsumoto Yushi Seiyaku Co., Ltd., Expandance Series from Expancel, and the like. In the case of a thermally expanded microballoon, the unexpanded resin microcapsule usually has a diameter of about 1 to 50 μm, and is expanded at an appropriate heating temperature to have a diameter of about 10 to 500 μm. It can be.

  Further, an inorganic filler or the like may be attached to the surface for the purpose of giving the strength of the hollow filler. In this case, in order to sufficiently reduce the thermal conductivity in the silicone rubber composition, the true specific gravity of the hollow filler is preferably 0.01 to 1.0, more preferably 0.01 to 0.5. It is. However, when a thermally expanded microballoon is used, the true specific gravity of the microballoon when not expanded is preferably about 0.5 to 1.4. If the true specific gravity is too small, not only is it difficult to mix and handle, but the pressure resistance of the hollow filler is insufficient and it is destroyed during molding, making it impossible to reduce the weight and decrease the thermal conductivity.

  Moreover, when specific gravity is too large, the thickness of the shell of a hollow filler will be large, and the case where a heat conductivity fall may not become enough.

  Further, the average particle diameter of the hollow filler is 500 μm or less, preferably 300 μm or less, and if the average particle diameter is too large, the hollow filler is destroyed by the injection pressure at the time of molding, and the thermal conductivity becomes high, Problems such as an increase in surface roughness after roll forming occur. The lower limit of the average particle diameter of the hollow filler is not particularly limited, but is usually 10 μm, particularly 20 μm. In addition, the average particle diameter here can be normally calculated | required as a weight average value (or median diameter) by a laser beam diffraction method.

  The amount of the hollow filler is 0.1 to 200 parts by weight, preferably 0.2 to 150 parts by weight, more preferably 0.5 to 100 parts by weight with respect to 100 parts by weight of the thermosetting organopolysiloxane composition. Part. In this case, it is preferable to blend so that the content of the hollow filler in the silicone rubber composition for a heat fixing roll is 10 to 80%, particularly 15 to 75% by volume. If the volume ratio is too small, the decrease in thermal conductivity is insufficient, and if it is too large, molding and blending are difficult, and the molded product may be brittle without rubber elasticity.

  In addition, when the thermally expanded microballoon is mixed into the organopolysiloxane composition without being inflated, the unexpanded microballoon is added to 100 parts by weight of the organopolysiloxane composition in consideration of the thermal expansion of the microballoon. A heat insulating layer with good heat insulating properties can be formed by mixing about 0.1 to 10 parts by weight and heat curing.

  On the other hand, as the thermosetting organopolysiloxane composition, a thermosetting organopolysiloxane composition having a known composition for forming a silicone rubber layer can be used. It may be of type.

  The structure of the organopolysiloxane composition basically has a linear structure, but may partially have a branched structure, a cyclic structure, or the like. The molecular weight is not particularly limited and can be used from a low-viscosity liquid to a high-viscosity raw rubber. However, in order to cure and become a rubber-like elastic body, the viscosity at 25 ° C. is 100 centipoise. It is above, and it is usually preferable that it is 100-1,000,000, especially 500-100,000.

  In the thermosetting organopolysiloxane composition, as other components, silica fine particles, a filler such as calcium carbonate, a silicone resin as a reinforcing agent, carbon black, conductive zinc white, Conductive agents such as metal powders, nitrogen-containing compounds and acetylene compounds, phosphorus compounds, nitrile compounds, carboxylates, tin compounds, mercury compounds, sulfur compounds and other hydrosilylation reaction control agents, heat-resistant agents such as iron oxide and cerium oxide, It is optional to mix an internal mold release agent such as dimethyl silicone oil, an adhesiveness imparting agent, a thixotropic property imparting agent, and triethylene glycol as a foaming agent.

  Here, the silicone rubber composition preferably has a cured product (silicone rubber) having a thermal conductivity of 0.2 W / m · K or less, particularly 0.15 W / m · K or less. It is preferable to adjust the blending composition to achieve. If the thermal conductivity is higher than 0.2 W / m · K, the object of the present invention cannot be achieved.

  The thickness of the heat-insulating silicone rubber layer 22b is not particularly limited. However, in order to form a small-diameter belt having an effective heat-insulating property and a heat capacity that is not excessively large, the thickness is 0.5 to 3.0 mm. The thickness is preferably 0.8 to 2.5 mm.

  The outer surface of the heat insulating belt may be covered with a release layer 22c. The release layer 22c is heated by the radiant heating device 24 over a long period of time, is subjected to many frictions from the recording material P, and is further exposed to toner. For this reason, the release layer 22c is required to have good heat resistance, slidability, and toner release properties. Examples of preferable materials that satisfy such requirements include fluororesin, polyphenylene sulfide, polysulfone, polyetherimide, polyethersulfone, polyetherketone, liquid crystal polyester, polyamideimide, and polyimide.

  The fluororesin is formed of a fluororesin coating agent, a fluororesin tube, or the like. For example, polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), or fluorinated ethylene. Examples include polypropylene copolymer resin (FEP), polyvinylidene fluoride resin (PVDF), and polyvinyl fluoride resin (PVF). The coating may be any method for coating the surface of the heat insulating belt, such as latex, Daiel latex (made by Daikin Industries, Ltd., fluorine latex), dipping coating using a dispersion, spray coating, or the like.

(B) Manufacturing method example of the heat insulating belt The manufacturing method of the heat insulating belt 22 is not particularly limited, but will be described below using FIG. 5 as an example.

  FIG. 5 is a schematic cross-sectional view of an example of a manufacturing apparatus for the heat insulating belt 22.

  105 is a cylindrical mold for casting silicone rubber, 102 is an end cap mold having a casting hole 103, and 104 is an end cap mold positioned opposite to 102. Reference numeral 101 denotes a core mold for holding the base layer 22 a of the heat insulating belt 22. For example, the core mold 101 is dipped into a polyimide varnish, and after baking imidization, a polyimide base layer 22 a is obtained and inserted into the cylindrical mold 105. . At this time, the inner surface of the cylindrical mold 105 may be previously filled with, for example, PFA pellets, or a fluororesin tube may be interposed. After the core mold 101 holding the base layer 22a is inserted into the cylindrical mold 105, the end caps are closed by the end cap molds 104 and 102, and then the liquid silicone composition mainly composed of the organopolysiloxane is used as the end cap. It injects into the heat insulation layer molding part 106 of the cylindrical mold 105 from the casting hole 103 of the mold 102. Although the silicone rubber composition needs to be cured after casting as described above, the curing conditions are not particularly limited. Generally, it is heat-cured at 100 to 150 ° C. for 10 minutes to 1 hour, removed from the end cap molds 104 and 102 and the cylindrical mold 105, and further post-cured at 180 to 200 ° C. for 2 to 4 hours. It is preferable. Examples of the manufacturing method include obtaining the heat insulating belt 22 by removing the core die 101 after the silicone composition is cured by heating as described above.

  In addition, the surface release layer 22c is coated by post-processing such as dipping coating or spray coating after curing the silicone rubber, or a method in which the heat-shrinkable tube is inflated with air and the heat-insulating belt 22 is inserted and then thermally contracted. There are methods, and the manufacturing method, order, and the like can be arbitrarily determined.

  In addition, when forming a fluororesin coating agent or a fluororesin tube as the release layer 22c, the contact surface with the silicone rubber layer is obtained by corona discharge treatment, sodium naphthalene method, sputter etching method, liquid ammonia method, etc. It is preferred to favor adhesion with silicone rubber. Furthermore, primer treatment may be used to improve the adhesion durability.

  The thickness of the release layer 22c is also selected as appropriate, but is preferably 1 to 50 μm, particularly preferably 5 to 30 μm.

(C) Other heat insulating belt examples As the silicone rubber composition forming the heat insulating layer 22a, there is a method of adding a water-absorbing polymer and water in addition to the above-mentioned hollow filler. Such silicone rubber compositions include 0.1 to 50 parts by weight of a water-absorbing polymer, 10 to 200 parts by weight of water, 100 parts by weight of an organopolysiloxane composition, a curing catalyst such as a platinum compound catalyst, and a SiH polymer. A composition formed by heat molding after forming a composition to which a crosslinking agent is added may be used as the heat insulating layer. In this case, heating is performed in the following three or two stages. That is, in the first stage, the silicone base polymer is not substantially cured and moisture is not evaporated, and the mold is formed by heating at 100 ° C. or less, preferably 50 to 80 ° C. for 10 to 30 hours. Next, in the second stage, the molded product is heated at 120 to 250 ° C., preferably 120 to 180 ° C. for 1 to 5 hours to evaporate water contained therein and water-containing impurities. Depending on the heating conditions when the moisture evaporates, the independent bubbles may be converted into an open cell structure or may not be converted. If the curing speed is high, the number of independent bubbles increases without conversion, and if controlled so that substantial curing due to crosslinking does not occur, the structure is converted to an open cell structure. And in the final third stage, the obtained porous body is heated at 180 to 300 ° C., preferably 200 to 250 ° C. for 2 to 8 hours, to proceed with curing, so that a desired porous rubber-like elastic body is obtained. Complete the silicone rubber layer.

  In the case of two-stage heating, there is a method in which the two stages after the heating stage are continuously performed at the same heating temperature. In this case, since curing is performed at a high temperature, there is a tendency that curing is performed with independent bubbles.

(D) Radiation heating device and reflector As the radiation heating source 24, a halogen heater or a carbon heater is used. The reflecting member 25 has a curved shape so as to contain the radiation heating source 24. As a reflecting member (hereinafter referred to as a reflecting plate) 25, a high-purity aluminum material in which at least the inner surface including the radiant heating source 24 is anodized, or gold plating by PVD processing for the purpose of maintaining increased reflection and reflectance. Further, a metal plate such as an aluminum material or a copper material subjected to silver plating is used as appropriate, and the reflectance is 90% or more. The surface of the heat insulating belt 22 is rapidly heated mainly by infrared light by the radiation heating source 24 and the reflecting plate 25 described above. That is, the surface of the heat insulating belt 22 is rapidly heated by reflecting the infrared light emitted from the radiant heating source 24 by the reflecting plate 25 and irradiating the surface of the heat insulating belt 22.

(E) Backup roller The material of the backup roller 21 is not particularly limited as long as it is a material that does not bend greatly due to the pressure applied to the pressure roller 30, but the heat capacity is as small as possible. A member having mechanical strength is suitable. For example, the core metal 21a is formed of an iron material such as free-cutting steel (SUM), and a porous ceramic member is covered around the core metal 21a to form the central large-diameter core shaft portion 21b. As a result, even when the backup roller 21 is formed with a small diameter, it is composed of a member having a high Young's modulus, so it is difficult to bend and is uniform in its longitudinal direction (direction perpendicular to (intersects with) the recording material conveyance direction Y on the recording material surface). It becomes easy to form a fixing nip width.

(F) Pressure roller The pressure roller 30 forms an elastic layer 32 such as silicone rubber as a pressure center large-diameter core shaft portion around a core metal 31 made of iron such as aluminum or free-cutting steel (SUM), Further, a release layer 33 having good release properties is formed on the surface by a fluorine resin coating agent, a fluorine resin tube or the like. Examples of the resin include polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), fluorinated ethylene polypropylene copolymer resin (FEP), polyvinylidene fluoride resin (PVDF), A polyvinyl fluoride resin (PVF) etc. can be mentioned. Other coatings include latex and Daiel latex (made by Daikin Kogyo Co., Ltd., fluorine-based latex), and in the case of coating coating, any method such as dipping coating using a dispersion or spray coating can be used. Also good.

  The elastic layer 32 of the pressure roller 30 is preferably a silicone rubber layer containing a hollow filler or bubbles, or a foamed rubber layer in a conventional example, as with the heat insulating layer 22b of the heat insulating belt 22. This is because the amount of heat that escapes from the surface of the heat insulating belt 22 to the pressure roller 30 can be reduced, and the time during which the surface of the heat insulating belt 22 is heated can be shortened. That is, if the heat capacity of the pressure roller 30 is large and the heat conductivity is as large as possible, the heat received from the outer surface is easily absorbed and the surface temperature is unlikely to rise. As a result, the time for the heat insulation belt surface to reach a desired temperature is extended. Therefore, as the elastic layer 32 of the pressure roller 30, a material having as low a heat capacity as possible, a low thermal conductivity, and a high heat insulating effect is more advantageous for the rise time of the surface of the heat insulating belt 22.

  Here, the solid rubber layer of the silicone rubber generally has a thermal conductivity of 0.25 to 0.29 W / m · k, the foam rubber has 0.11 to 0.15 W / m · k, The value is about half that of solid rubber. The specific gravity related to the heat capacity is about 1.05-1.30 for solid rubber and about 0.55-0.85 for foamed rubber. Therefore, it can be seen that a preferred form of the elastic layer 32 is a foamed rubber having a high thermal insulation effect with a thermal conductivity of 0.15 W / m · k or less and a specific gravity of 0.85 or less.

  However, as mentioned in the previous examples, foam rubber is a highly toxic gas generated during the manufacturing process, odor problems, problems with inhibition of curing, and foam rubber molding that uses hydrogen gas produced as a by-product during curing. In addition, problems such as the explosive nature of hydrogen gas and the need to handle uncured materials during storage, and it is difficult to lower the thermal conductivity from the viewpoint of durability, so it is easy to form uniform bubbles When the heat insulating layer 22b similar to the heat insulating belt 22 containing a hollow filler or air bubbles is used for the elastic layer 32 of the pressure roller 30, it is easy to achieve both shortening of warm-up time and first printout time and durability. In particular, in a heat insulating layer formed from a composition containing a hollow filler in organopolysiloxane or a composition containing a water-absorbing polymer and water, the thermal conductivity is further reduced to 0.07 to 0.11 W / m · k. It is also possible to reduce the warm-up time and the first printout time, and to ensure durability.

(3) Heat Fixing Operation In FIG. 3, reference numeral 35 denotes a driving gear for applying a rotational driving force to the pressure roller 30. The drive gear 35 is provided at one longitudinal end of the core 31 of the pressure roller 30 and receives a rotational driving force from the rotational drive system M to move the pressure roller 30 in the counterclockwise direction of the arrow (FIG. 2). Driven at a speed (process speed). When the recording material P is not introduced into the fixing nip portion N, the heat insulating belt 22 receives the rotational force of the pressure roller 30 through the fixing nip portion N and rotates in the clockwise direction indicated by the arrow. Further, the backup roller 21 receives the rotational force of the heat insulating belt 22 through the pressure nip portion K, and is rotated along with the heat insulating belt 22 in the clockwise direction of the arrow. As described above, the pressure roller 30 and the heat insulating belt 22 are rotated while forming the fixing nip portion N, respectively.

  In the rotation state of the pressure roller 30, the heat insulating belt 22, and the backup roller 21, the temperature control circuit 110 takes in temperature detection information from the temperature detection means 23. Based on the detected temperature information, the temperature control circuit 110 finely adjusts the energization duty to the radiant heating source 24 by using a control method such as wave number control or phase control for the heater drive circuit 111 to thereby control the temperature of the heat insulating belt 22. Control is performed to maintain a predetermined fixing temperature (target temperature) at which the unfixed toner image T on P can be fixed. As a result, the temperature of the fixing nip N is maintained at the fixing temperature.

  When the recording material P on which the unfixed toner image T is formed and supported is introduced into the fixing nip portion N by the fixing inlet guide IG while the temperature of the fixing nip portion N is maintained at the fixing temperature, the recording material P is fixed to the fixing nip. In the portion N, the pressure roller 30 and the heat insulating belt 22 are nipped and conveyed. In the conveying process, the unfixed toner image T on the recording material P is heated and fixed by the heat obtained from the surface of the heat insulating belt 22 and the pressure corresponding to the pressure applied by the backup roller 21 and the pressure roller 30. The state of the unfixed toner image T and the heat insulating belt 22 in the fixing nip N at this time will be described with reference to FIG.

  FIG. 6 is an explanatory view showing a state of heat-fixing an unfixed toner image by a heat insulating belt.

  When the recording material P on which the unfixed toner image T is formed is introduced into the fixing nip portion N, the unfixed toner image T is pressed by the heat insulating belt 22 and is crushed. At this time, since the heat insulating belt 22 has elasticity, it is slightly deformed corresponding to the unevenness of the toner image T. As a result, the surface of the heat insulating belt 22 is recessed so as to wrap the toner image T. As a result, the contact area of the heat insulating belt 22 increases with respect to the toner image T, and heat is efficiently transferred from the heat insulating belt 22 to the toner image T on the recording material P. As a result, the toner image T on the recording material P is fixed on the recording material P as a permanent image.

(4) Performance Confirmation Test Example As described above, the first printout time, the durability performance, and the fixing uniformity of the heat fixing device 15 in this embodiment were confirmed. The process speed of the image forming apparatus used was 260 mm / sec, and an experiment was performed using a laser beam printer that performed printing of 45 sheets per minute. The configuration of the heat fixing device used for each comparison is as follows.

  First, common parts of the heat fixing device 15 used in the experiment will be described.

The backup roller 21 disposed inside the heat insulating belt 22 has a bulk density of 0.5 g / cm ³ and an internal porosity as the central large-diameter core shaft portion 21b around the SUM core metal 21a having an outer diameter of 9 mm. A ceramic porous body formed of 42% with a thickness of 1.5 mm is used.

  In order to form the fixing nip portion N via the heat insulating belt 22, the pressure roller 30 forms a hollow filler-containing silicone rubber layer having a thickness of 3 mm as an elastic layer 32 around the SUM cored bar 31 having an outer diameter of 12 mm. Further, a PFA tube having a thickness of 30 μm was coated on the outermost layer.

  As a hollow filler, an acrylonitrile balloon having a particle size of 80 μm is mixed with 30 parts by weight with respect to 100 parts by weight of the organopolysiloxane composition, and a small amount of triethylene glycol is blended so that bubbles are connected. 30, the thermal conductivity of 32 parts of the elastic layer was set to 0.12 W / m · K.

  As the radiant heating source 24, a halogen heater having a glass tube diameter of 6 mm and an output of 800 W at a voltage of 100 V is used, and a reflector made of mirror-finished aluminum having a reflectivity of 91% and anodized outside the halogen heater. 25 was placed.

  Further, as the heat insulating belt 22, a polyimide layer having a thickness of 30 μm is used as a base layer 22a, a heat insulating rubber is formed as a heat insulating layer 22b on the outer side thereof with a thickness of 1.1 mm, and a PFA resin of 10 μm is formed on the surface as a release layer 22c. Coated. The peripheral length of the heat insulating belt 22 was 58 mm as the inner peripheral length of the polyimide layer as the base layer. Therefore, the outer peripheral length of the heat insulating belt 22 is about 74 mm.

  In the following experiment, when the amount of the hollow filler contained in the heat insulating elastic layer 22b of the heat insulating belt 22 is varied to change the thermal conductivity, and the heat insulating rubber having each heat conductivity is used, the respective first printout times (FPOT) ), Durability performance and fixing uniformity were comparatively evaluated.

  The first printout time is from when the laser printer receives a print signal and starts rotating operation and energizing operation until the unfixed toner image T on the recording material P is discharged onto the discharge tray 17 after being heated and fixed. Time was measured.

Concerning the durability performance, the A4 size recording material P having a basis weight of 80 g / m ² is continuously printed, and continues until a trouble such as the heat insulation belt 22 breaks, and the fixing nip portion N is satisfactorily reached. The number of recording materials P that have passed through (fixed and conveyed by the fixing nip portion N) was counted.

For the evaluation of the fixing uniformity, a halftone image in which an image for one dot line and a non-image portion for two dot lines are alternately formed on a recording material P with a 600 dpi image, and a solid black printed on the entire surface with a solid black. An A4-sized recording material P having a basis weight of 80 g / m ² was heat-fixed using an image, fixing unevenness was visually identified in five stages, and a rank sample was prepared and visually evaluated. The rank was an integer from 1 to 5, with 1 being the worst and 5 being the best. Each halftone image and solid black image were printed 8 by 8, and the average rank of 16 ranks in total was compared.

  The amount of the hollow filler and the thermal conductivity of the heat insulating belt 22 used for each experiment are shown below.

In addition, as a hollow filler mix | blended with the heat insulation belt 22 used this time, the thermal expansion microballoon of particle size 20-30 micrometers and true specific gravity 1.05 called Matsumoto microsphere series F-85 by Matsumoto Yushi Seiyaku Co., Ltd. was used. . The amount of hollow filler mixed in each experiment indicates the amount of mixing of the microballoon when it is not inflated with respect to 100 parts by weight of the organopolysiloxane composition.
[Experiment 1] Hollow filler: 0.05 parts by weight, thermal conductivity: 0.16 W / m · K
[Experiment 2] Hollow filler: 0.1 parts by weight, thermal conductivity: 0.15 W / m · K
[Experiment 3] Hollow filler: 0.3 part by weight, thermal conductivity: 0.135 W / m · K
[Experiment 4] Hollow filler: 1 part by weight, thermal conductivity: 0.12 W / m · K
[Experiment 5] Hollow filler: 7 parts by weight, thermal conductivity: 0.08 W / m · K
[Experiment 6] Hollow filler: 10 parts by weight, thermal conductivity: 0.07 W / m · K
[Experiment 7] Hollow filler: 12 parts by weight, thermal conductivity: 0.06 W / m · K
As a comparative test, a case where a foamed silicone rubber layer is used as the heat insulating layer shown in the conventional example is shown (Japanese Patent Laid-Open No. 2002-278338).

In addition, as a comparative test, when only the foamed silicone rubber layer is an elastic layer (Comparative 1), when a silicone rubber layer is further formed on the foamed silicone rubber layer as in the conventional example (Comparative 2), Further, in the configuration of Comparative 2, the same confirmation was made when the circumference of the heat insulating belt was doubled (116 mm in inner circumference) (Comparative 3).
[Comparison 1] Foamed silicone rubber 1.1 mm, thermal conductivity: 0.13 W / m · K
[Comparison 2] Foamed silicone rubber 0.9 mm, solid rubber 0.2 mm,
Thermal conductivity: 0.17 W / m · K, inner circumference 58 mm
[Comparison 3] Foamed silicone rubber 0.9 mm, solid rubber 0.2 mm,
Thermal conductivity: 0.17 W / m · K, inner circumference 116 mm
The comparison results in each experiment are shown below.

  From the above results, it can be seen that when the thermal conductivity of the heat insulating belt exceeds 0.15 W / m · K, the first printout time is long and the warm-up time is long.

  In recent years, it has been desired to shorten the first printout time. From this viewpoint, the thermal conductivity of the heat insulating belt 22 is 0.15 W / m · K or less, preferably 0.12 W / m · K or less.

  Moreover, it turns out that durability performance becomes severe as content of a hollow filler increases. This indicates that the proportion of hollow balloons is large, and the thickness of the silicone rubber interposed between the balloons is reduced, and breakage is likely to occur. Therefore, from this viewpoint, it is necessary to determine the mixing amount of the hollow filler and the water-absorbing polymer to be a predetermined value or less.

  Moreover, when the amount of hollow balloons mixed in increases, the fixing uniformity is also slightly tended to be impaired due to some difference in the amount of hollow balloons interposed.

  On the other hand, in the case of the heat insulation belt of the conventional method compared, when the elastic layer is formed only by the foamed silicone rubber layer (Comparative 1), the first printout time can be kept moderate, but the fixing uniformity is deteriorated.

  It can also be seen that when the solid rubber layer is coated on the outside of the foamed silicone rubber layer, the first printout time is delayed. This is a phenomenon that occurs because the heat capacity increases.

  Also, in the case of a heat-insulating belt with a short circumference, if foamed silicone rubber is used as the heat-insulating layer, foaming from the thin part of the wall surface is sufficient due to the non-uniformity of the foamed silicone rubber cells against the load caused by bending. A durable life could not be obtained. Therefore, when foamed silicone rubber is used, the circumference of the heat insulating belt must be lengthened, and this increases the heat capacity, which increases the first printout time.

  Next, the heat conductivity of the heat insulating belt was kept constant, and a comparative experiment was performed by changing the thickness of the heat insulating layer of the heat insulating belt. Other configurations are the same as in the above experiment, and the amount of thermally expanded microballoon mixed in the heat insulating belt 22 is 3 parts by weight with respect to 100 parts by weight of the organopolysiloxane composition, and the thermal conductivity is 0.10 W / m · K. Insulation belt was obtained. The thickness of the heat insulation belt 22 was confirmed by shaking at 0.4 to 3.4 mm.

  The comparison results are shown below.

  From the above results, it can be seen that if the thickness of the heat insulating layer 22b of the heat insulating belt 22 is made too thin, heat easily escapes into the heat insulating belt, resulting in a long first printout time. Therefore, the thickness is 0.5 mm or more, preferably 0.8 mm or more. On the other hand, when the thickness is increased, the heat insulating belt 22 has rigidity, and surface cracks are likely to occur due to a load caused by bending. Therefore, the thickness of the heat insulating layer 22b of the heat insulating belt 22 is 3.0 mm or less, preferably 2.5 mm or less.

  Regarding the fixing uniformity, the influence of the thickness of the heat insulating belt 22 was not observed in the range shaken this time.

  Next, confirmation was carried out in a system in which an elastic layer made of solid rubber was coated on the outside of the heat insulating layer 22b of the heat insulating belt 22 in this example. The aim is that in Experiments 8 to 11, the number of endurance sheets reached 350,000 sheets or more, but as a result of continuing the durability thereafter, cracks were observed on the surface between 380,000 sheets and 450,000 sheets. When the crack was observed, it was cracked from the wall portion between the balloons of the heat insulating layer.

  For this reason, the warm-up time is somewhat sacrificed, but in order to see whether it is possible to further extend the durability life, in the configuration of the experiment 10, the elastic layer 22d (0.15 mm solid rubber formed outside the heat insulating layer 22b) FIG. 7) was formed, and the first print time and the number of durable sheets were confirmed in the same manner. As a result, the first printout time was 12.8 seconds, and the number of durable sheets was able to achieve 500,000 sheets or more.

  Furthermore, when the amount of the microballoon of the heat insulating layer 22b was doubled, the first printout time was 8.9 sec, and the durable number was also able to achieve 500,000 or more.

  From the above, it was found that a method of providing a thin solid rubber layer on the outer side of the heat insulating layer 22b of the heat insulating belt 22 can be adopted in this embodiment in order to extend the number of durable sheets. In particular, in this embodiment, the heat insulating belt 22 is smaller in diameter than the conventional foamed silicone rubber in terms of durability, and the heat conductivity of the heat insulating layer 22b is higher than that of the conventional example. It was possible to reduce the initial printout time and achieve both durability and durability.

  In addition, when the heat insulation belt 22 is used as the heat insulation belt 22 in the configuration of Experiment 10 above, a polyimide layer is used as the base layer 22a, and a heat insulation belt molded in a state where the hollow balloon-mixed silicone rubber layer as the heat insulation layer 22b is joined is used. Due to the endurance, 250,000 sheets passed and breakage occurred from the joint. Although there is a possibility of improvement by making a manufacturing method in which the load is not applied by the joint and by making the joint close to a seamless state by post-processing, at the present time from the above results, the layers 22a, 22b, 22c, and 22d of the heat insulating belt 22 are formed seamlessly. It is desirable to do.

  According to the present example, a balloon-containing silicon elastic layer or a bubble-containing silicon elastic layer produced from an organopolysiloxane composition mixed with a hollow filler or an organopolysiloxane composition containing a water-absorbing polymer and water is used as a heat insulating layer. By constituting the heat insulating belt 22 as 22b, the surface of the heat insulating belt 22 can be rapidly heated by rapidly heating the heat insulating belt 22 having a low heat capacity and a short circumference by external heating.

  In addition, balloons and bubbles contained in the balloon-containing silicon elastic layer and the bubble-containing silicon elastic layer formed as the heat-insulating layer 22b of the heat-insulating belt 22 are uniformly dispersed in the elastic layer with a substantially uniform and fine particle size. Even if the peripheral length of the heat insulation belt is reduced and a bend with a small radius of curvature is given to the heat insulation belt, there is no weak place like the silicon sponge layer, so there is a possibility that the foam breaks like the silicon sponge layer. Becomes lower. For this reason, there is a sufficient margin against breakage due to bending, and a long life is achieved.

  In addition, the generation of highly toxic gas and the odor problem during the molding of foamed silicon rubber, which has been used in the past, has been solved, and there is no problem of curing inhibition. Furthermore, sponge rubber molding that uses hydrogen gas produced as a by-product during curing. The need for problems such as the explosive nature of hydrogen gas and the need to handle uncured materials during storage has been eliminated.

  Furthermore, since each layer 22a, 22b, 22c of the heat insulating belt 22 is formed with a seamless seamless structure, a weak portion that is a cause of breakage is not formed, so that a heat insulating belt having excellent durability is formed. .

  Further, the heat insulating belt 22 is heated externally, and the recording material P on which the unfixed toner image T is formed is introduced into the fixing nip portion N formed between the heat insulating belt and the pressure roller 30, thereby heating and fixing. When the heat fixing device is used, the time for heating the surface of the heat insulating belt by the heating source 24 is short, and the quick start property is excellent.

  For this reason, the fixing nip portion N can be rapidly heated at the same time as the start of the image forming operation even if no power is supplied to the heating source 24 in a state where the image forming operation is not performed. Therefore, it is not necessary to perform standby heating as in the prior art, and it is possible to save energy and reduce the warm-up time and the first printout time.

  Further, as the pressure roller 30, an organopolysiloxane composition in which a hollow filler is mixed in the material used for the elastic layer 32 as in the heat insulating layer 22b of the heat insulating belt 22, or an organopolysiloxane containing a water absorbing polymer and water. A balloon-containing silicon elastic layer or a bubble-containing silicon elastic layer manufactured from the composition is used, and the thermal conductivity of the elastic layer 32 is 0.15 W / m · K or less, so that the heat is applied from the surface of the heat-insulated belt 22 heated externally. By suppressing the amount of heat flowing out to the pressure roller 30 side, the quick start property can be further increased, and the warm-up time and the first printout time can be further reduced.

  Further, in the fixing nip portion N, the surface of the heat insulating belt 22 is in contact with the surface on which the unfixed toner image T is formed. The elasticity of the elastic layer 22d provided on the surface of the heat insulating belt 22 causes the surface on the recording material P to be fixed. By achieving the fixing uniformity due to the effect of enveloping the toner image T, it is possible to achieve the uniformity of the image and prevent the uneven fixing in the halftone image. As a result, high image quality can be achieved at the same time.

  Therefore, by using the heat insulating belt 22 having the above-described configuration, it is possible to achieve excellent performance in all of the shortening of the temperature rising time at the time of start-up, the reduction of power consumption, and further high speed, high image quality, and long life, and stable fixing performance. Can be provided.

  In addition, it is possible to provide a heat insulating belt formed of a material in consideration of environmental safety, and a heat fixing device including the heat insulating belt.

  In this embodiment, at least two roller members are arranged inside the heat insulating belt, and a tension is applied to the heat insulating belt by the roller member to form a wide fixing nip portion N between the pressure roller, thereby reducing the diameter. A heat fixing device that can be sufficiently applied to increase the speed of the image forming apparatus even with the above heat insulating belt will be described.

  The configuration of the heat fixing apparatus of this embodiment is shown in FIGS.

  FIG. 8 is a cross-sectional side view of an example of a heat fixing apparatus according to the present embodiment, and FIG. 9 is a cross-sectional side view of a modification of the heat fixing apparatus. In the present embodiment, the same members and members having the same functions as those of the heat fixing device 15 shown in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The heat fixing device 15 shown in FIG. 8 will be described.

  Inside the heat insulating belt 22, a backup roller 21 and a stretching roller 27 are disposed as roller members. As a material of the tension roller 27, any member may be used as long as it is a member having a small diameter and little bending. Even if it is composed of the same member as the backup roller 21, there is no problem. Further, it is desirable that the backup roller 21 and the stretching roller 27 are respectively attached to the apparatus chassis side plates (not shown) on the front side and the back side so as to be rotatable by bearings.

  By applying tension to the heat insulating belt 22 with the two roller members (the backup roller 21 and the stretching roller 27) in the above configuration, the traveling locus of the heat insulating belt 22 is stabilized, and the two roller members 21 and 27 are stabilized. The pressure roller 30 is disposed at a position facing the peripheral surface of the heat insulating belt 22 that travels between the rotation centers of the two roller members 21 and 27 with respect to the heat insulating belt 22 that is tensioned by the above. In this way, the portion of the heat insulating belt 22 that contacts the pressure roller 30 is deformed so that the center of curvature of the heat insulating belt 22 is outside the heat insulating belt 22, that is, the pressure roller 30 side.

  As a result, it is possible to form a wide fixing nip width formed between the heat insulating belt 22 and the pressure roller 30, and the pressing force applied between the backup roller 21 and the pressure roller 30 can be kept low. A sufficient fixing nip width can be formed.

  Therefore, since the bending of each roller member (the backup roller 21, the stretching roller 27, and the pressure roller 30) can be suppressed low by reducing the applied pressure, the heat insulating belt 22, the backup roller 21, the stretching roller 27, and the pressure roller 30. The diameter can be reduced and the heat capacity can be reduced, and even with a small heat-fixing apparatus, it is possible to cope with the high speed of the image forming apparatus.

  Next, the heat fixing device 15 shown in FIG. 9 will be described.

  The heat fixing device 15 shown in FIG. 9 has a configuration in which a contact heating means 40 is brought into contact with the surface of the heat insulating belt 22 as a heating means. The other configuration is the same as that of the heat fixing device 15 shown in FIG.

  The configuration of the contact heating means 40 is a planar heating element that rapidly heats while sliding on the surface of the heat insulating belt 22 by a heater 46, and details thereof will be described with reference to FIG.

  10A is a longitudinal cross-sectional model view of the contact heating means 40, and FIG. 10B is a plan view of the surface side of the heater 46 and an explanatory diagram of the temperature control system.

In FIG. 10, reference numeral 41 denotes an elongated substrate of the heater 46, which is formed of an insulating ceramic substrate such as alumina or aluminum nitride, or a heat resistant resin substrate such as polyimide, PPS, or liquid crystal polymer. Along the longitudinal direction on the surface of the substrate 41, for example, an energization heating resistor layer 42 of Ag / Pd (silver palladium), RuO ₂ , Ta ₂ N or the like has a thickness of about 10 μm and a width of about 1 to 5 mm by screen printing or the like. It is formed by coating in the form of a line or a strip.

  A protective sliding layer 43 may be provided on the heat insulating belt 22 side (surface side) of the heater 46 so as to protect the energized heat generating resistance layer 42 of the heater 46 within a range that does not impair the thermal efficiency. However, the thickness of the protective sliding layer 43 is preferably thin enough to improve the surface properties. Examples include perfluoroalkoxy resin (PFA), polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-hexafluoropropylene resin (FEP), ethylenetetrafluoroethylene resin (ETFE), polychlorotrifluoroethylene resin ( Dry film lubricant, glass coat, which is coated with a fluorine resin layer such as CTEF) or polyvinylidene fluoride (PVDF) alone or mixed, or made of graphite, diamond-like carbon (DLC), molybdenum disulfide, etc. A protective sliding layer 43 such as

  Further, in order to prevent contamination of the surface of the heating heater 46 due to sliding of the heating heater 46 and the heat insulating belt 22, a method of interposing a rotatable thin seamless film between the heating heater 46 and the heat insulating belt 22, A method of interposing a take-up type thin sheet can also be employed. However, in that case, it is desirable to interpose a polyimide sheet, a metal sheet, or a film that is sufficiently thin and mixed with a heat conductive filler so as not to disturb the heat flow from the heater to the heat insulating belt. For example, when a seamless film formed of SUS material is interposed, the thickness is desirably 40 μm or less, preferably 30 μm or less. When a polyimide sheet or the like is interposed, a heat conductive filler such as BN is mixed, and the thickness is 30 μm or less, preferably 25 μm or less.

  Further, when aluminum nitride or the like having good thermal conductivity is used as the substrate 41 of the heater 46, the energization heating resistor layer 42 may be formed on the opposite side of the heat insulating belt 22 with respect to the substrate 41. good.

  Further, by providing a curvature in the concave direction on the sliding surface of the heat insulating belt 22 of the heater 46 in a direction following the outer peripheral surface of the heat insulating belt 22 along the traveling locus of the heat insulating belt 22, The contact area can be increased. Thereby, the heat generated by the heater 46 can be efficiently transmitted to the heat insulating belt 22. Moreover, by doing in this way, the pressure between the heater 46 for heating and the heat insulation belt 22 can be reduced, and the rotational torque of the breaking belt 22 can be reduced.

  45 (FIG. 10 (a)) is a heat insulating stay holder for holding a heater, which is formed of a heat resistant resin such as liquid crystal polymer, phenol resin, PPS, PEEK, etc. Thermal efficiency during heating increases. Therefore, a hollow filler such as a glass balloon or a silica balloon may be included in the resin layer.

  A temperature detection means 44 such as a thermistor for detecting the temperature of the substrate 41 raised in response to the heat generated by the energized heat generating resistor layer 42 is disposed on the back surface of the substrate 41 opposite to the heat insulating belt 22 of the heater 46. ing. This temperature detecting means 44 is provided for the purpose of controlling the temperature of the heater 46 for heating or monitoring abnormal temperature rise. When used for temperature control, the heating heater 46 is appropriately controlled by appropriately controlling the duty ratio, wave number, etc. of the voltage applied to the energization heating resistor layer 42 from the electrode portion 42a at the longitudinal end of the substrate 41. Heat and adjust the temperature. That is, the detected temperature information from the temperature detecting means 44 is sent via the temperature control circuit 47 to the triac element 48 as a heater heater energizing driver. The triac element 48 performs energization ON / OFF to the AC power source 49 based on the energization signal of the temperature control circuit 47.

  As described above, in the modification of the present embodiment, the surface of the heat insulating belt 22 is heated by directly contacting the surface of the heat insulating belt 22 with the heater for heating having the temperature detecting means 44 disposed on the back surface of the substrate 41. Therefore, there is an advantage that the load on the surface of the heat insulating belt 22 can be reduced.

Performance Confirmation Test Example In the configuration of the heat fixing device in the present embodiment, experiments were conducted with regard to the heat insulating belt 22 and the diameter of each roller member, and the speedup of the image forming apparatus.

  The image forming apparatus used in the experiment is a laser beam printer with a process speed of 260 mm / sec and a laser beam printer with a process speed of 320 mm / sec (55 prints per minute) as in the first embodiment. Experiments were performed with the following configurations of the heat-fixing apparatus using printers of respective speeds.

Insulation belt A: The inner peripheral length of the insulation belt with the same configuration as in Experiment 10 shown in Example 1
58mm, heat insulation layer thickness is 0.8mm, 10μm fluorine on the surface
A resin coat was applied.

Insulation belt B: the inner circumference of the insulation belt is 50 mm, the silicone rubber material of the insulation layer, and
The type and amount of microballoons are the same as for the heat insulation belt A.
A fluororesin coat having a thickness of 10 μm and a surface of 10 μm was formed.

  Further, a ceramic porous roller having an outer diameter of 4 mm and an internal porosity of 42% was disposed inside each of the heat insulating belts A and B as the backup roller 21 and the stretching roller 27.

  As with the pressure roller 30, as in Experiment 10 of Example 1, a hollow filler-containing silicone rubber layer having a thickness of 3 mm as an elastic layer 32 around a SUM core 31 having an outer diameter of 12 mm, and a release layer 33 as the outermost layer. A roller C coated with a 30 μm-thick PFA tube, a 3 mm-thick hollow filler-containing silicone rubber layer as an elastic layer 32 around a SUM core metal 31 with an outer diameter of 10 mm, and a 30 μm-thick PFA as a release layer 33 on the outermost layer A roller D coated with a tube was prepared. In both cases, the thermal conductivity of the elastic layer 32 was set to 0.12 W / m · K.

  Each member was combined in the above configuration, and the first print time and durability were compared and evaluated by the same evaluation method as in Example 1.

  The fixing nip width is defined as the contact width between the heat insulating belt 22 and the pressure roller 30, and the recording material P on which a solid black image is formed is heated in the fixing nip portion N for 10 seconds and has different glossiness. The width of the portion was measured to obtain a fixing nip width, and about 8 mm was secured.

  The pressing position by the pressure roller 30 is the tension roller 27 side downstream from the rotation center of the backup roller 21 disposed inside the heat insulating belt 22, and the center of the radius of curvature of the heat insulating belt 22 is the pressure roller 27. It was configured to be on the side.

  The heating source is the same as that in the first embodiment.

Experiments 14 to 17 are for a process speed of 260 mm / sec, and Experiments 18 to 21 are for a speed of 320 mm / sec.
[Experiments 14 and 18]

Insulation belt A, pressure roller C
[Experiments 15 and 19]

Insulation belt B, pressure roller C
[Experiments 16 and 20]

Insulation belt A, pressure roller D
[Experiment 17, 21]

Insulation belt B, pressure roller D
The experimental results are shown below.
(1) When the process speed is 260 mm / sec

  As described above, in the heat fixing device 15 shown in the present embodiment, it is possible to ensure a short first print time and a long-life durability.

  Here, in Experiment 14, although the configurations of the heat insulation belt 22 and the pressure roller 30 are the same as those in Experiment 10 in the first embodiment, the first print time is slightly faster because of the heat insulation belt 22 and the pressure roller 30. The main factor is that the fixing nip width to be formed is wide and the surface temperature of the heat insulating belt necessary for fixing can be set low.

  Here, as a comparative experiment, the contact position of the pressure roller 30 on the heat insulating belt 22 is moved to the upstream side in the recording material conveyance direction Y in the configuration of the experiment 14, and the heat insulating belt 22 is in close contact with the backup roller 21. When the same test was performed when the pressure roller contact position was moved to a portion, the fixing nip width was reduced to 3 mm, and the surface temperature of the heat insulating belt 22 increased by 20 ° C. in order to keep the fixing possible state. The print time has been delayed to 12.5 sec.

  From the above, providing the pressure roller contact position between the rotation centers of at least two roller members 21 and 27 arranged inside the heat insulating belt 22 widens the fixing nip width and shortens the first print time. It turns out that it becomes possible.

  It can also be seen that when the outer diameters of the heat insulating belt 22 and the pressure roller 30 are reduced, the first print time is shortened slightly. In particular, it can be seen that the reduction in diameter of the heat insulating belt 22 greatly contributes to shortening the first print time.

  Contrary to this, although the number of durable sheets is slightly lowered due to the reduction in the diameter of the heat insulating belt 22, there is a sufficient number of durable sheets. This is a longer life than the experiment 10 shown in the first embodiment. The reason for this is that a sufficient fixing nip width can be obtained even if the pressure applied between the pressure roller 30 and the backup roller 21 is kept small. Depending on what is obtained.

Therefore, at least two roller members (21, 27) are arranged inside the heat insulating belt 22, the heat insulating belt 22 and the pressure roller 30 are reduced in diameter, and the fixing nip width is sufficiently increased. This is a method for improving the quick start performance without causing an extreme decrease.
(2) When the process speed is 320 mm / sec

  As described above, in this embodiment, when the speed of the image forming apparatus is increased, the recording material conveyance speed is increased, but the temperature of the surface of the heat insulating belt 22 necessary for fixing increases, so the first print time is slightly delayed. I understand that

  However, in the present embodiment in which the diameters of the heat insulating belt 22 and the pressure roller 30 can be reduced, the quick start performance can be achieved even for the high speed image forming apparatus by reducing the diameter of the heat insulating belt 22 and the pressure roller 30. It can be seen that this is a configuration that can be maintained sufficiently.

  According to the present embodiment, the heat insulating belt 22 is stretched in a state where tension is applied by at least two roller members 21 and 27, and the heat insulating belt 22 that runs between the centers of at least two roller members is supported. By contacting the pressure roller 30, the width of the fixing nip formed by the pressure roller 30 and the heat insulating belt 22 can be increased. For this reason, it is possible to form a fixing nip width having a sufficient width even with the heat insulating belt 22 having a short circumference.

  As a result, it is possible to obtain a sufficient time for heating the unfixed toner image T on the recording material P, and it is possible to realize sufficient heat fixing for speeding up the image forming apparatus. Further, even when the diameter of the pressure roller 30 is reduced, a sufficient fixing nip width can be formed.

[Others]
1) In the heat fixing device 15, the backup roller 21 is driven and rotated. However, the backup roller 21 may be rotated and driven separately.

  2) Although the heat fixing device 15 is configured to heat the surface of the heat insulating belt 22 by the radiant heat source 24 in a non-contact state with the heat insulating belt 22, the method of heating the surface of the heat insulating belt 22 is not limited to this. Absent. For example, a contact-type heating means using a ceramic heater, a method of heating from the inner surface of a highly heat-conductive thin film by a radiation heating means such as a halogen lamp, or a highly heat-conductive thin film having flexibility and heat resistance (heating) Any method may be used as long as the surface of the heat insulating belt 22 can be heated from the outside, such as a method of heating the heat insulating belt 22 via a film).

  3) The image heating apparatus according to the present invention is not limited to the use as the heat fixing apparatus of the embodiment, but is an assumed fixing apparatus that temporarily fixes an unfixed image on a recording material, and a fixed image on the recording material is reheated to gloss, etc. It is also effective when used as an image heating apparatus such as a surface modification apparatus for modifying image surface properties.

1 is an overall configuration diagram of an example of an image forming apparatus. FIG. 3 is a cross-sectional side view of an example of a heat fixing device according to the first embodiment. FIG. 3 is a partially cutaway front view of the heat fixing device according to the first embodiment. Explanatory drawing of layer structure of a heat insulation belt. The cross-sectional model figure of an example of the manufacturing apparatus of a heat insulation belt. FIG. 3 is an explanatory diagram showing a state of heat fixing an unfixed toner image by a heat insulating belt. Layer constitution explanatory drawing which shows the other example of a heat insulation belt. FIG. 5 is a cross-sectional side view of an example of a heat fixing device according to a second embodiment. FIG. 10 is a cross-sectional side view of another example of the heat fixing apparatus according to the second embodiment. (A) is a longitudinal cross-sectional model figure of a contact-type heating means, (b) is a top view of the surface side of a heater for heating, and explanatory drawing of a temperature control system. The cross-sectional side model figure of the heat fixing apparatus which concerns on a prior art example. The cross-sectional side model figure of the heat fixing apparatus which concerns on a prior art example. The cross-sectional side model figure of the heat insulation belt concerning this invention. The cross-sectional side model figure of the heat insulation belt concerning this invention.

Explanation of symbols

21 ... backup roller, 22 ... heat insulation belt, 23 ... temperature detection means,
24 ... Radiation heating source, 25 ... Reflector, 22a ... Base material (heat resistant resin sheet),
22b ... heat insulation layer, 22c ... release layer, 30 ... pressure roller,
40 ... Contact heating means

Claims (15)

  A heating member having a heat insulating layer, the surface of which is heated by a heating means from the outside, and which contacts the material to be heated and heats the image on the material to be heated, the heat insulating layer being a hollow filler in the organopolysiloxane composition A heating member, characterized in that it is formed by firing and curing after forming a blend containing bismuth, or a blend of an organopolysiloxane composition and a water-absorbing polymer and water.   The heat insulating layer is a compound in which 0.1 to 200 parts by weight of a hollow filler having an average particle size of 500 μm or less is blended with 100 parts by weight of the organopolysiloxane composition, or water absorption with respect to 100 parts by weight of the organopolysiloxane composition. 2. The heating member according to claim 1, wherein the heating member is formed by firing and curing after forming a blend containing 0.1 to 50 parts by weight of a functional polymer and 10 to 200 parts by weight of water.   The heating member according to claim 2, wherein the heat insulating layer is configured seamlessly.   The heating member according to claim 1, wherein the surface of the heat insulating layer on the heating means side is covered with an elastic layer.   The heating member according to claim 4, wherein the elastic layer is configured seamlessly.   The heating member according to claim 5, wherein the elastic layer is made of solid rubber.   The heating member according to claim 1, wherein the surface is coated with a release layer.   The heating member according to claim 7, wherein the release layer is configured seamlessly.   The heating member according to claim 7, wherein the release layer is made of a fluororesin.   The heating member according to claim 1, wherein the heating member has a belt shape. A heating member having a heat insulating layer; a pressure member that presses against the heating member to form a nip portion; and a heating unit that heats the surface of the heating member from the outside. In the image heating apparatus for heating the image on the material to be heated,
The heat insulating layer of the heating member is formed by baking and curing after forming a compound in which a hollow filler is blended with an organopolysiloxane composition, or a compound in which a water-absorbing polymer and water are blended in an organopolysiloxane composition. An image heating apparatus.   The shape of the heating member is an endless belt shape, the heating member has at least two roller members, and the heating member is tensioned by the roller members. The image heating apparatus described.   13. The nip portion is formed between a heating member stretched between rotation centers of at least two roller members arranged inside the heating member and a pressure member. Image heating device.   The pressure member has an elastic layer, and the elastic layer is fired after forming a compound in which a hollow filler is blended with an organopolysiloxane composition, or a compound in which a water-absorbing polymer and water are blended in an organopolysiloxane composition. The image heating apparatus according to claim 11, wherein the image heating apparatus is formed by curing.   The heat insulating layer is a compound in which 0.1 to 200 parts by weight of a hollow filler having an average particle size of 500 μm or less is blended with 100 parts by weight of the organopolysiloxane composition, or water absorption with respect to 100 parts by weight of the organopolysiloxane composition. The image heating apparatus according to claim 14, wherein the image heating apparatus is formed by firing and curing after forming a blend containing 0.1 to 50 parts by weight of a conductive polymer and 10 to 200 parts by weight of water.