JP2006292935A - Heater and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heater for maintaining proper fixing level over long periods of time by improving the glossiness, preventing film damages, and preventing malfunctions, such as fixing defect from occurring having a flexible moving member 16, a backup member supporting the moving member by having a slide face slid with the moving member, and a pressure member forming the backup member and a nip member by sandwiching the moving member, sliding and moving the moving member on the face of the backup member and pressuring and heating a material to be heated, while sandwiching and conveying the material to be heated between the moving member of the nip part and the pressure member. <P>SOLUTION: The moving member 16 has at least a base layer 1 sliding on the backup member, an elastic layer 2, provided on the face side opposite to the backup member side on the base layer 1, and further has a mold release layer 3 thereon, and the mold release layer 3 is made a coating layer that blends a plurality of fluorine resins. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heating apparatus that pressurizes and heats a material to be heated, and an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus that includes the heating apparatus as an image heating apparatus.

  In general, electrophotographic image forming apparatuses are widely used in copying machines, laser beam printers, and the like. In the electrophotographic method, an electrostatic force is used to form an image of toner particles on a recording material such as recording paper by a transfer method or a direct method, and the toner image is recorded on the recording material by a fixing device as an image heating device. A stable image is formed by being melted and fixed thereon.

  As the fixing device, a heat roller method is widely used. Recently, a film heating system has been put into practical use.

  As the heat roller system, a pressure roller pair of a fixing roller (heating roller) and a pressure roller is a basic configuration, and the roller pair is rotated, and a fixing nip portion (heating nip portion) which is a mutual pressure contact portion of the roller pair A recording material on which an unfixed toner image to be image-fixed is formed and carried is introduced and nipped and conveyed, and the unfixed toner image is applied to the surface of the recording material by the heat of the fixing roller and the pressure of the fixing nip. It is to fix.

  As a fixing roller and a pressure roller used in this heat roller type fixing device, for example, a heat-resistant elastic layer such as silicon rubber or fluorine rubber is provided on the surface of a hollow roller such as aluminum, and toner or The outermost layer is coated with a release layer such as a coating layer of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) / PTFE (polytetrafluoroethylene) to prevent paper dust from sticking. In general, the fixing roller is heated from the inside by a halogen heater or the like to maintain the surface temperature at a predetermined fixing temperature and perform heat fixing.

  A film heating type fixing device (heating device) is disclosed in, for example, Patent Documents 1 to 4 and the like related to the earlier proposal of the present applicant. That is, a heat-resistant film (fixing film) as a flexible moving member is generally sandwiched between a ceramic heater as a heating body and an elastic pressure roller as a pressure member, and a nip portion (fixing nip portion, contact) A recording material on which an unfixed toner image to be fixed as a heated material is formed and supported between the film and the pressure roller in the nip portion, and is nipped and conveyed together with the film Thus, the unfixed toner image is heated and fixed on the surface of the recording material by heating and pressing at the nip portion.

  This film heating type fixing device can be configured as an on-demand type device using a ceramic heater and a film having a low heat capacity as a film, and energizes the ceramic heater as a heat source only when the image forming apparatus performs image formation. It is only necessary to generate heat at a predetermined fixing temperature, and the waiting time from the power-on of the image forming apparatus to the image forming executable state is short (quick start property), and the power consumption during standby is greatly reduced (saving) Power).

  The film as the flexible moving member is a cylindrical or endless belt-like film as a rotating body, and the driving method is to use a film pressure-contacted by a film guide for guiding the inner peripheral surface of the film and a pressure roller. There is a method of rotating the pressure roller by driving the pressure roller (pressure roller driving method), and conversely rotating the pressure roller by driving an endless belt-like film stretched between the driving roller and the tension roller. is there. Moreover, the film as a flexible movement member can also be set as the apparatus structure which makes it the long end member wound by the roll, and draws out and moves this through a heating body.

  In addition, as a fixing device of an image forming apparatus that performs full-color image formation, the applicant of the present application disclosed in Patent Documents 5, 6, and 7, as a configuration in which an elastic layer is formed on the film surface, OHT transparency, color reproducibility, and Proposals have been made to improve fixing properties such as uneven gloss and image roughness.

There is also a configuration in which a heat source is also provided in the pressure roller so that the pressure roller is also heated.
JP-A-63-313182 Japanese Patent Laid-Open No. 2-157878 JP-A-4-44075 JP-A-4-204980 Japanese Patent Laid-Open No. 10-48868 JP 2000-187407 A JP 2003-308949 A

  In the fixing device, fluororesin, fluororubber, silicone rubber or the like is employed as the heat-resistant release layer that is the surface layer.

  In particular, in a fixing device of a type having an elastic layer on the film surface, since the total thickness is a thin layer, there has been a problem of coexistence of strength against surface scratches and image quality such as image gloss uniformity.

  That is, in the conventional release layer, if the strength of the release layer is weak, there is a problem that the surface is damaged during paper wrinkling or jamming. For this reason, the strength of the release layer was increased to prevent the occurrence of scratches on the film surface, and the releasability was maintained throughout the durability. However, if the strength of the release layer is increased, the deterioration of the fixed image becomes remarkable and the image quality is not good. In particular, when a thin film was used, the fixed image tended to deteriorate significantly.

Accordingly, an object of the present invention is to prevent film scratches and to prevent problems such as poor fixing particularly in a heating device using a film having an elastic layer, and to provide good fixability over a long period of time. It is to provide a heating device that can be maintained.

  A typical configuration of the heating device according to the present invention for achieving the above object includes a flexible moving member, a backup member having a sliding surface that slides on the moving member, and supporting the moving member. A pressure member that forms the nip portion with the backup member sandwiched between the movement members, and slidably moves the movement member on the surface of the backup member, and the movement member of the nip portion and the pressure member In the heating apparatus that pressurizes and heats the material to be heated while sandwiching and conveying the material to be heated with the pressure member, the moving member includes at least a base layer that slides with the backup member, and the backup of the base layer It has an elastic layer provided on the side opposite to the member side, and a release layer provided on the elastic layer, and the release layer is formed of a plurality of types of fluororesins and has a thickness of 5 μm or more. 40 μm or less It is characterized by.

  By configuring the film heating type heating device (fixing device) as described above, the following effects can be obtained.

  1) By using a thin film (flexible moving member) having an elastic layer, it is possible to configure an on-demand type device with improved thermal response, and also to provide OHT permeability, color reproducibility, and It is possible to improve the fixing property, such as improvement of uneven gloss and image roughness.

  2) By using a surface layer that is blend-coated with multiple types of fluororesins, it is possible to improve the film formability, and at the same time, prevent film scratches and prevent defects such as uneven gloss and poor fixing. High fixability can be maintained.

  3) A desired strength and surface property can be obtained as a release layer easily and inexpensively by forming a coating film on the elastic layer by spray coating or the like and baking it.

(1) Example of Image Forming Apparatus FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus. The image forming apparatus of this example is a full-color image printer using an electrophotographic process.

  Reference numeral 101 denotes an electrophotographic photosensitive drum (image bearing member) made of an organic photosensitive member or an amorphous silicon photosensitive member, which is rotationally driven in a counterclockwise direction indicated by an arrow at a predetermined process speed (peripheral speed).

  The photosensitive drum 101 is uniformly charged with a predetermined polarity and potential by a charging device 102 such as a charging roller during the rotation process.

  Subsequently, the charging processing surface is subjected to scanning exposure processing of target image information by laser light 103 output from a laser optical box (laser scanner) 110. A laser optical box 110 outputs a laser beam 103 modulated (on / off) in accordance with a time-series electric digital pixel signal of target image information from an image signal generation device such as an image reading device (not shown) to output a rotating photosensitive drum. The surface is subjected to scanning exposure, and an electrostatic latent image corresponding to target image information scanned and exposed on the surface of the rotary photosensitive drum 101 is formed by this scanning exposure. Reference numeral 109 denotes a mirror that deflects the output laser light from the laser optical box 110 to the exposure position of the photosensitive drum 101.

  In the case of full-color image formation, scanning exposure / latent image formation is performed on a first color separation component image of a target full-color image, for example, a yellow component image, and the latent image is subjected to yellow development in the four-color developing device 104. The yellow toner image is developed by the operation of the device 104Y. The yellow toner image is transferred onto the surface of the intermediate transfer drum 105 at the primary transfer portion T1 which is a contact portion (or proximity portion) between the photosensitive drum 101 and the intermediate transfer drum 105. The surface of the rotary photosensitive drum 101 after the transfer of the toner image to the surface of the intermediate transfer drum 105 is cleaned by the cleaner 107 after removal of adhered residues such as transfer residual toner.

  The process cycle of charging / scanning exposure / development / primary transfer / cleaning as described above includes a second color separation component image (for example, magenta component image, magenta developer 104M is activated) of the target full-color image, a third An intermediate transfer member is sequentially executed for each color separation component image of a color component image (for example, cyan component image, cyan developing device 104C is activated) and a fourth color component image (for example, black component image, black developing device 104BK is activated). Four color toner images of a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image are sequentially superimposed and transferred onto the surface of the drum 105, and a color toner image corresponding to the target full-color image is synthesized and formed.

  The intermediate transfer drum 105 has a middle-resistance elastic layer and a high-resistance surface layer on a metal drum. The intermediate transfer drum 105 is in contact with or close to the photosensitive drum 101 at the same peripheral speed as the photosensitive drum 101. And a bias potential is applied to the metal drum of the intermediate transfer drum 105 to transfer the toner image on the photosensitive drum 101 side to the surface of the intermediate transfer drum 105 by the potential difference with the photosensitive drum 101.

  The color toner image synthesized and formed on the surface of the intermediate transfer member 105 is not transferred to the secondary transfer portion T2 at the secondary transfer portion T2 which is a contact nip portion between the rotating intermediate transfer drum 105 and the transfer roller 106. The image is transferred onto the surface of the recording material P fed from the illustrated paper feeding unit at a predetermined control timing. The transfer roller 106 supplies a charge having a polarity opposite to that of the toner from the back surface of the recording material P, thereby sequentially transferring the combined color toner images sequentially from the surface of the intermediate transfer drum 105 to the recording material P side.

  The recording material P that has passed through the secondary transfer portion T2 is separated from the surface of the intermediate transfer drum 105, introduced into the fixing device 100, subjected to heat-fixing processing of an unfixed toner image, and is subjected to non-fixing as a color image formed product. The paper is discharged onto the illustrated paper discharge tray.

  After the color toner image is transferred to the recording material P, the rotating intermediate transfer drum 105 is cleaned by the cleaner 108 after removal of the adhering residue such as transfer residual toner and paper dust. The cleaner 108 is always held in a non-contact state with the intermediate transfer drum 105, and is in contact with the intermediate transfer drum 105 during the secondary transfer of the color toner image from the intermediate transfer drum 105 to the recording material P. Retained.

  Also, the transfer roller 106 is always held in a non-contact state with the intermediate transfer drum 105, and recording is performed on the intermediate transfer drum 105 during the secondary transfer of the color toner image from the intermediate transfer drum 105 to the recording material P. The contact state is maintained via the material P.

  A mono-color image print mode such as a monochrome image can also be executed. A double-sided image print mode or a multiple image print mode can also be executed.

  In the double-sided image print mode, the recording material P on which the first-side image has been printed exiting the fixing device 100 is turned upside down via a recirculation conveyance mechanism (not shown), and sent again to the secondary transfer unit T2 to be the second side. In response to the toner image transfer, the toner image is again introduced into the fixing device 100 and undergoes a toner image fixing process on two sides, whereby a double-sided image print is output.

  In the multiple image print mode, the recording material P on which the first image has been printed out of the fixing device 100 is sent to the secondary transfer portion T2 again without being turned upside down via a recirculation conveyance mechanism (not shown). The second toner image is transferred to the surface on which the second image has been printed, and is again introduced into the fixing device 100 and undergoes the second toner image fixing process, whereby a multiple image print is output.

(2) Fixing device 100
The fixing device 100 in this embodiment basically uses a cylindrical heat-resistant film (fixing film) as a flexible member disclosed in JP-A-4-44075 to 44083, 4-204980 to 204984, and the like. , Film heating system, pressure roller drive system (tensionless type).

  2 is a front model view of the fixing device 100 with the intermediate portion omitted, FIG. 3 is a longitudinal cross-sectional model diagram with the intermediate portion omitted, and FIG. 4 is a transverse cross-sectional model diagram.

  Reference numeral 15 denotes a heating assembly (film unit), and 19 denotes an elastic pressure roller as a pressure member, and a fixing nip portion N as a contact portion is formed by pressure contact between both of them.

1) Heating assembly 15
The heating assembly 15 includes a cylindrical or endless heat-resistant fixing film (hereinafter referred to as a film) 16 as a flexible moving member, a ceramic heater (hereinafter referred to as a heater) 17 as a heating body, and a support member. The film guide 18, the pressurizing rigid stay 20, and the annular flange member 25 as a film displacement movement restricting means are assembled.

  The film 16 includes a base layer made of a heat-resistant resin such as polyimide, polyimide amide, PEEK, PES, PPS, etc., having a thickness of 20 to 100 μm, and an intermediate layer of silicon rubber or fluorine having a thickness of 50 to 500 μm. A heat-resistant elastic layer such as rubber, and a composite layer film in which the outer peripheral surface is coated with 10 to 30 μm of PTFE, PFA, FEP or the like to form a release layer can be used. In this example, silicon rubber was formed on the outer peripheral surface of the polyimide film, and PTFE and PFA blended and coated with a diameter of 20 mm was used. The film 16 will be described in detail later in section 4).

The heater 17 is a member having a low heat capacity and a temperature that rapidly rises upon energization, with the direction intersecting the recording material passing direction as a longitudinal direction. This heater 17 is basically composed of a substrate such as insulating ceramics such as alumina or aluminum nitride, a heat-resistant resin such as polyimide, PPS, or liquid crystal polymer, and a means such as screen printing on the substrate surface. An energization heating resistance layer made of Ag / Pd (silver palladium), RuO ₂ , Ta ₂ N, etc., formed by coating and firing in a linear or narrow strip shape having a thickness of about 10 μm and a width of about 1 to 5 mm, and the energization An insulating layer such as a glass coat that covers the substrate surface on which the heating resistance layer is formed, and the substrate surface that is electrically connected to the energization heating resistance layer are formed, and a voltage is supplied from the feeding circuit through the feeding connector. And a surface heating type heater having a low heat capacity as a whole.

  Then, the surface of the heater 17 (the heater substrate surface side on which the energization heating resistor layer and the glass coat insulating layer are formed) is used as a film-adhering sliding surface, and the film guide 18 has a central portion on the outer surface side of the film guide 18. It is fixed and held by being fitted and exposed to the outside in the heater insertion groove formed along the length. The heater 17 is supplied with power from the AC power supply (not shown) to the energized heat generating resistor layer, and the energized heat generating resistor layer generates heat over the entire length, so that the temperature rises rapidly and rapidly. The temperature rise of the heater 17 is detected by a temperature detection element (not shown) arranged on the back side of the heater, and the electric power supplied from the AC power source to the energization heating resistor layer of the heater 17 by the control circuit unit (not shown) is phase and wave number. The temperature of the heater 17 is controlled to a predetermined fixing temperature under the control of the control or the like. The temperature control configuration of the heater 17 is not limited to the above, and is based on temperature information detected by temperature detection means such as the surface temperature of the pressure roller 20 or a thermistor disposed at an arbitrary position on the inner surface of the film 16 of the nip N. In addition, the surface temperature of the film 16 required for fixing the toner image T on the recording material P at the nip portion N is set as a target set temperature, and the energization of the heater 17 to the energization heating resistance layer is maintained. The amount can also be controlled.

  The film guide 18 is a heat-resistant and heat-insulating member having a substantially semi-circular cross-sectional shape having a longitudinal direction that intersects the recording material passing direction, and is phenolic resin, polyimide resin, polyamide resin, polyamideimide resin, PEEK. Insulating and heat-resistant materials such as resin, PES resin, PPS resin, fluororesin (PFA, PTFE, FEP, etc.), LCP (liquid crystal polymer) resin, and mixed resins thereof are used. It serves to back up the film 16, pressurize the nip N, support the heater 17, and transport stability when the film 16 rotates.

  The cylindrical film 16 is loosely fitted on a film guide 18 on which a heater 17 is fixedly supported.

  The annular flange member 25 is fitted to the end portion side of the film guide 18 to regulate the end portion of the film 16.

  The pressurizing rigid stay 20 is inserted inside the film guide 18, and both end portions thereof protrude outward from both end portions of the film guide 18.

2) Elastic pressure roller 19
An elastic pressure roller (hereinafter referred to as a pressure roller) 19 as a pressure member is a core metal 19a provided with an elastic layer 19b such as silicone rubber to reduce the hardness, and both ends of the core metal 19a are connected to the apparatus. The bearing is rotatably held between the front side and the rear side chassis side plate (not shown). In order to improve surface properties, a fluororesin layer such as PTFE, PFA, FEP or the like may be further provided on the outer periphery.

  Above the pressure roller 19, the heating assembly 15 is disposed with the lower surface side of the film guide 18 facing downward, and both ends of the pressure rigid stay 20 and spring receiving members 21 and 21 on the apparatus chassis side plate side, A pressing force is applied to the pressurizing rigid stay 20 by contracting the pressurizing springs 22 and 22 respectively. As a result, the lower surface of the film guide provided with the heater 17 and the pressure roller 19 are pressed against each other with the film 16 against the elasticity of the elastic layer 19b of the pressure roller 19, and a nip having a predetermined width as a contact portion. Part N is formed. The heater 17 exists in the nip portion N. The film 16 is backed up at the nip N by a film guide 18 and a heater 17.

  In this example, the ceramic heater 17 as the heating body and the film guide 18 that supports the ceramic heater 17 have a sliding surface that slides on the fixing film 16 as a moving member, and is a backup member that supports the fixing film 16. is there.

3) Device Operation In FIG. 4, the pressure roller 19 is rotationally driven by the driving means M in the counterclockwise direction indicated by the arrow. A rotational force acts on the film 16 by the frictional force between the pressure roller 19 and the outer surface of the film 16 by the rotational driving of the pressure roller 19. As a result, the film 16 rotates around the film guide 18 in the clockwise direction indicated by the arrow while sliding with the inner surface in close contact with the lower surface of the heater 17 at the nip portion N (pressure roller driving method). The film 16 is in a rotating state having a peripheral speed substantially corresponding to the rotational peripheral speed of the pressure roller 19.

  In order to reduce the mutual sliding frictional force between the lower surface of the heater 17 and the inner surface of the film 16 in the nip portion N, a lubricant such as heat resistant grease is provided between the lower surface of the heater 17 and the inner surface of the film 16 in the nip portion N. Intervene.

  The rotation of the pressure roller 19 is started based on the print start signal, and the heater 17 starts to heat up. When the rotation peripheral speed of the film 16 is stabilized by the rotation of the pressure roller 19 and the temperature of the heater 17 rises to a predetermined temperature, a material to be heated is interposed between the film 16 and the pressure roller 19 in the nip portion N. The recording material P carrying the toner t is introduced with the toner image carrying surface side of the film 16 side, so that the recording material P adheres closely to the lower surface of the heater 17 via the film 16 at the nip portion N. Part N moves and passes with the film 16. During the moving and passing process, the heat of the heater 17 is applied to the recording material P through the film 16 and the toner image t is heated and fixed on the surface of the recording material P. The recording material P that has passed through the nip portion N is separated from the surface of the film 16 and conveyed.

4) Fixing film 16
FIG. 5 is a schematic cross-sectional view showing the layer structure of the fixing film 16. The fixing film 16 is characterized in that an elastic layer 2 made of a rubber elastic body and a release layer 3 are sequentially provided on a base layer 1 mainly composed of polyimide resin. The base layer 1 side is the heater sliding surface side (fixing film inner surface side), and the release layer 3 side is the pressure roller contact surface side (fixing film outer surface side).

a: Base layer 1
In order to satisfy the conditions such as thermal conductivity and mechanical strength necessary for the fixing film 16, the base layer 1 mainly composed of polyimide resin preferably has a thickness in the range of 20 to 100 μm. Furthermore, in order to improve the thermal responsiveness of the fixing film, the thermal conductivity of the polyimide film base layer is 0.42 W / m · ° C. (1.0 × 10 ⁻³ cal / cm · sec · ° C.) or more. preferable. Usually, the thermal conductivity of polyimide resin is 0.25 W / m · ° C. (0.6 × 10 ⁻³ cal / cm · sec · ° C.) or less, but as an additive to the resin material, for example, BN, AlN, or SiC By blending these, the thermal conductivity of the base layer can be increased to the above range.

  On the other hand, it is also possible to use a metal sleeve as a base material. In this case, relatively high strength can be obtained and the thickness can be set thin.

  Thus, by using a heat-resistant resin with a low heat capacity or a thin metal film as a base material, the heat capacity can be reduced as a rotating body compared to the case where a metal roller is used as a base material. The required power can be reduced, and an on-demand type device can be configured.

b: Elastic layer 2
As the rubber elastic body constituting the elastic layer 2, a soft one having a low rubber hardness is preferable. For example, silicone rubber having a JIS-A hardness of 1 to 70 °, more preferably 5 to 40 ° can be suitably used. The thickness of the elastic layer is preferably in the range of 0.05 to 1 mm, more preferably in the range of 0.1 to 0.5 mm. If the thickness of the elastic layer is less than 0.05 mm, it is difficult to fix the film so that it is difficult to give sufficient elasticity to the film, and the OHT permeability, color reproducibility, gloss unevenness and image The improvement effect of fixing property such as improvement of roughness cannot be obtained. On the other hand, if it is thicker than 1 mm, the heat responsiveness of the fixing film will be impaired.

c: Release layer 3
The constituent material of the release layer 3 is formed of a plurality of fluorine-based resins in which PFA is used as a base material and a relatively soft fluorine resin such as PTFE is mixed therewith.

  The mixing ratio is preferably a mixture of a relatively soft resin. For example, when PTFE is blended with PFA, a mixture of PTFE at a ratio of 50 to 90 wt%, more preferably 60 to 80 wt% is preferable. It is.

  When the mixing ratio is less than 50 wt%, the film formability at the time of coating deteriorates, and it becomes difficult to form a release layer having a uniform surface property at low cost. On the other hand, when the mixing ratio exceeds 90 wt%, it is impossible to obtain a stable release property through the strength against scratches and durability.

  The thickness of the release layer is preferably 5 to 40 μm, more preferably 10 to 30 μm. When the thickness of the release layer is less than 5 μm, the durability and the strength against scratches are reduced, and when it is thicker than 40 μm, the effect of providing a rubber elastic layer cannot be obtained or the thermal response is disadvantageous. Therefore, both are not preferable.

  The fixing film of the present invention can be produced, for example, as follows. First, in manufacturing the polyimide film as the base layer 1, a polyimide precursor solution such as a polyamic acid solution in which thermally conductive inorganic particles and conductive fillers are dispersed on the outer surface of a mold serving as a core is uniform. It is made to adhere with a sufficient thickness, and is dried and imidized by heating to form a tubular product of a polyimide film.

  Any method may be used for attaching the polyimide precursor solution to the core with a uniform thickness. For example, a predetermined amount of the polyimide precursor solution is attached to the upper periphery of the core by a general method such as dipping or coating. After that, an outer mold having a predetermined clearance is fitted to the outside of the metal core body whose longitudinal direction is held vertically, and the outer mold is lowered by its own weight. The “coat” method and the like are particularly suitable.

  The rubber elastic body layer 2 can be provided on the surface of the cylindrical polyimide film 1 formed as described above by a method in which LTV silicone rubber is further coated and cured, or a method in which HTV silicone rubber is press-molded. The release layer 3 can also be easily formed in accordance with a conventional method such as dispersion coating with a fluororesin blend liquid having a desired blending ratio. Then, the image fixing film of the present invention is obtained by separating the cylindrical object having a multilayer structure from the core.

  The polyimide precursor that can be used as a raw material for the polyimide film in the present invention is not particularly limited, and examples thereof include those obtained by reacting an aromatic diamine and an aromatic tetracarboxylic acid. Examples of aromatic tetracarboxylic acids such as 3,3′-dimethoxy-4,4′-diaminodiphenyl ether and 3,3′-diaminophenyl ether include 3,3 ′, 4,4′-biphenyltetracarboxylic acid. Examples thereof include acid dianhydride and pyromellitic dianhydride. The reaction of these aromatic diamines with aromatic tetracarboxylic acid is carried out in an organic polar solvent such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone.

Example 1
As a polyimide precursor solution, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride having a viscosity of 2000 poise and aromatic diamine (4,4′-diaminophenyl ether) are used as a solvent, N-methyl- A polyimide precursor solution obtained by reacting in 2-pyrrolidone (NMP) was prepared.

Next, Si ₃ N ₄ (Shin-Etsu Chemical Co., Ltd. silicon nitride, thermal conductivity: 0.06 to 0.09 cal / cm · sec · ° C. as a thermally conductive inorganic filler having an average particle size of 0.6 μm. ) Powder was used.

After dispersing 10 g of the Si ₃ N ₄ powder in 40 ml of NMP and using an ultrasonic cleaner to disperse the secondary agglomerated particles into primary particles, the powder is put into the polyimide precursor solution. The mixture was stirred with a mixer to uniformly disperse the Si ₃ N ₄ particles. The mixing ratio of Si ₃ N ₄ to the solid content concentration of the polyimide precursor solution was 15 wt%.

  After that, an aluminum cylindrical core body having an outer diameter of 30 mm and a length of 500 mm is immersed in the polyimide precursor solution and pulled up, and a ring-shaped outer mold having an inner diameter of 31 mm is formed from the top of the cylindrical core body. The film was dropped by its own weight, and a film of a polyimide precursor solution having a thickness of about 500 μm was cast on the outer surface of the cylindrical core.

  Thereafter, this core is heated at 120 ° C. for 40 minutes and at 200 ° C. for 15 minutes to advance the removal of the solvent and the imide conversion reaction to form a tubular polyimide film having a thickness of 60 μm serving as a base layer. (Polyimide intermediate) was formed.

  Next, after coating the surface of this polyimide tube on the core with Hs20 ° LTV silicone rubber (product name XE15-751, manufactured by Toshiba Silicone Co., Ltd.), heat treatment was performed at 120 ° C for 30 minutes to achieve a thickness of 0.2 mm. A rubber elastic layer was formed. The surface of the obtained rubber elastic layer is spray-coated with a mixed solution of 70 wt% of PTFE with respect to PFA as a fluororesin, and then the temperature is 250 ° C. for completing the imidation reaction and firing the fluororesin. After performing heat treatment for 80 minutes, heat treatment was performed at 380 ° C. for 70 minutes to form a releasable surface layer having a thickness of 10 μm. Thereafter, the aluminum core was pulled out to obtain an image fixing film of the present invention having a multilayer structure.

  In addition, in order to ensure the adhesive strength between each layer, when it coats after apply | coating a primer, it will be excellent in the integrity without delamination. However, depending on the mixing ratio of the fluororesin mixture, the heat treatment conditions, etc., the same adhesive strength can be obtained even if the primer coating is omitted.

  The heat-resistant film thus produced was applied as the fixing film 16 of the fixing device of the image forming apparatus shown in FIGS. 1 and 2 to evaluate image output and the like. Table 1 shows the evaluation results.

  As a comparative example, the results of a release layer formed only with PFA (Comparative Example 1), a mixture of 20 wt% PTFE (Comparative Example 2), and a release layer formed only with PTFE (Comparative Example 3) Also shown.

As can be seen from Table 1, in Comparative Example 3, the releasability after endurance deteriorated and scratches were also generated.
In Comparative Example 1, the image quality (gloss uniformity) is not good. Further, in Comparative Example 2, the release properties after the endurance, scratches and image quality were all insufficient. On the other hand, this example was good for releasability, image quality, and scratches.

(Example 2)
This example is the same as Example 1 except that SUS is used as the base layer material. As the base layer, SUS304 (stainless steel) was formed into a cylindrical shape having an inner diameter of 30 mm and a thickness of about 30 μm by deep drawing, and then an elastic layer and a release layer were formed in the same manner as in Example 1 to form a fixing film. Obtained.

  Thus, by using a metal-based material as the base layer, the total thickness of the film can be reduced and the thermal conductivity can be increased, so that the thermal response can be improved.

  In this example as well, image evaluation was performed in the same manner. As a result, it was possible to ensure releasability through durability, and there were no scratches, and a good fixed image was obtained.

(Example 3)
In this example, a film was formed using PFA, FEP, and PTFE as the release layer material, and a mixed solution having a mixing ratio of PFA 20 wt%, FEP 10 wt%, and PTFE 70 wt%. That is, in contrast to the mixing ratio of PFA 30 wt% and PTFE 70 wt% in Example 1, in this example, the mixing ratio was such that part of PFA was replaced with FEP, such as PFA 20 wt%, FEP 10 wt%, and PTFE 70 wt%.

  By using FEP having a relatively low melting point, the firing temperature can be kept low, the manufacturing method can be made inexpensive, and even elastic layer species with relatively low heat resistance can be used. The degree of freedom of selection can be widened.

  Also in this example, by setting the mixing ratio of PTFE to “PFA + FEP” to 50 to 90 wt%, both scratch prevention and image quality can be achieved.

  In this example as well, image evaluation was performed in the same manner. As a result, it was possible to ensure releasability through durability, and there were no scratches, and a good fixed image was obtained.

(Other)
1) In the heating device of the embodiment, the flexible moving member (fixing film) 16 is a cylindrical or endless belt-like film as a rotating body, and the driving method thereof guides the inner peripheral surface of the film. The film pressure-contacted by the film guide and the pressure roller is driven by the rotation of the pressure roller (pressure roller drive system), but it is an endless belt-like film stretched by the drive roller and tension roller. It is also possible to adopt a device configuration in which the pressure roller is driven to rotate by driving. Moreover, the film as a flexible movement member can also be set as the apparatus structure which makes it the long end member wound by the roll, and draws out and moves this through a heating body.

  2) The heating element 17 is not limited to a ceramic heater, and other various heaters can be used. For example, an electromagnetic induction heating member such as an iron plate may be used as the heating body 17.

  3) The heating body 17 does not necessarily have to be located at the fixing nip N. For example, an apparatus configuration in which the heating body 17 is disposed on the upstream side of the fixing nip portion N with respect to the film moving direction may be employed.

  4) The heating mode of the fixing film 16 is not limited to the internal heating method, but may be an external heating method, or a heating method in which the fixing film itself generates electromagnetic induction heat.

  5) The pressure member is not limited to the roller body, and may be a form such as a rotating endless belt body.

  6) The heating device of the present invention is not limited to a fixing device, but an image heating device that is supposed to be worn, an image heating device that reheats a recording material carrying an image to improve the surface properties such as gloss, and other than the recording material The sheet-like material to be heated can be passed through and used as a heat treatment apparatus such as drying, heat laminating, hot press wrinkle removal, hot press curl removal and the like.

1 is a schematic configuration diagram of an example of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a front model view of the fixing device according to the embodiment of the present invention with an intermediate portion omitted. It is a longitudinal cross-sectional model figure of the intermediate part omission of the apparatus. It is a cross-sectional model figure of the same apparatus. FIG. 3 is an enlarged cross-sectional model view of a fixing film.

Explanation of symbols

  16 .. Fixing film (flexible member), 17 .. Heater (heating body), 18 .. Film guide, 19 .. Pressing member, 20 .. Stay for pressing, 25. , N ... Fixing nip

Claims (8)

A flexible moving member; a backup member having a sliding surface that slides against the moving member; and supporting the moving member; and a pressure member that sandwiches the moving member to form the backup member and the nip portion. The moving member is slid on the surface of the backup member, and the heated material is added while nipping and conveying the heated material between the moving member and the pressure member of the nip portion. In the heating device for pressure and heating,
The moving member has at least a base layer that slides with the backup member, an elastic layer provided on the opposite side of the base layer from the backup member side, and a release layer provided thereon. ,
The heating device, wherein the release layer is formed of a plurality of types of fluorine-based resins and has a thickness of 5 μm to 40 μm.   The heating device according to claim 1, wherein the release layer is formed by coating a mixed liquid in which a plurality of types of fluorine-based resins are mixed.   3. The heating apparatus according to claim 1, wherein the release layer uses a fluorine-based resin in which PFA and PTFE are mixed, and a mixing ratio of PTFE to PFA is set to 50 to 90 wt%.   The heating device according to any one of claims 1 to 3, wherein the moving member is a film-like rotating body including a resin or a metal as a base layer.   The heating apparatus according to claim 1, wherein a portion corresponding to the nip portion of the moving member sliding surface of the backup member is a heating body.   The heating apparatus according to claim 5, wherein the heating body is a ceramic heater.   7. An image forming apparatus comprising: an image forming unit that forms and supports an unfixed image on a recording material; and a fixing unit that heat-fixes the unfixed image on the surface of the recording material, wherein the fixing unit is any one of claims 1 to 6. An image forming apparatus, which is the heating apparatus described in 1.   The image forming apparatus according to claim 7, wherein the image forming unit is a color image forming unit that forms toner images of a plurality of colors on a recording material.