JP5127153B2 - Image heating device and film - Google Patents

Description

The present invention relates to an image heating apparatus and a film .

Image The heating device, for example, a fixing device and for fixing an unfixed image on the recording material as a solid Chakugazo, gloss increased apparatus increases the gloss of the image by heating the are fixed on a recording material an image or the like Can be mentioned.

  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. In recent years, a film heating type fixing device and an electromagnetic induction heating type fixing device for generating heat from the film itself have been put into practical use from the viewpoint of quick start and energy saving.

  The heat roller type fixing device has a basic configuration of a pressure roller pair of a fixing roller (heating roller) and a pressure roller. Then, the roller pair is rotated, and a recording material on which an unfixed toner image is formed and carried is introduced into a fixing nip portion (heating nip portion) which is a mutual pressure contact portion of the roller pair, and is nipped and conveyed. Then, the toner image is fixed to the surface of the recording material by heat and pressure by the applied pressure of the nip portion.

  A film heating type fixing device is disclosed in Patent Document 1 and the like, and is a fixed and supported heating body, a recording material on which one surface slides with the heating body and the other surface carries an unfixed toner image. And an image heating member that moves together in contact therewith. In general, a ceramic heater is used as the heating element. Specifically, the image heating member is a film member (fixing film: hereinafter referred to as a film) having heat resistance and flexibility. The unfixed toner image is heated by the heat of the heating body through the film and fixed on the recording material surface.

  This film heating type fixing device can be configured as an on-demand type (quick start) device using a ceramic heater and a low heat capacity member as a film. Therefore, it is only necessary to energize the ceramic heater to generate heat to a predetermined fixing temperature only when image formation is performed by the image forming apparatus, and the waiting time from power-on of the image forming apparatus to an image forming executable state is short. There are advantages such as significantly reduced power consumption during standby.

  In addition, for the film as the image heating member, a film using a metal such as stainless steel or nickel as the base layer or an elastic layer on the base layer is used in order to cope with speeding up and colorization of the image forming apparatus. The fixing device that has been disclosed is disclosed in Patent Documents 2, 3, 4, and the like.

  In other words, using a metal with higher thermal conductivity than the resin as the base layer of the film, increasing the thermal conductivity of the film and transferring the heat of the heater to the recording material more efficiently, the high speed of the image forming apparatus Adapted to In addition, by providing an elastic layer, the film surface follows the shape of multiple transferred toner images such as color images, and heat is uniformly applied to achieve uniform fixing corresponding to colorization. Yes.

  On the other hand, Patent Document 5 discloses an electromagnetic induction heating type fixing device that induces an eddy current in a film by magnetic flux and generates heat by the Joule heat. This makes it possible to directly generate heat by using the generation of induced current, and achieves a fixing process that is more efficient than a heat roller type fixing device using a halogen lamp as a heat source.

Further, in the film as the image heating member as described above, a surface release layer such as a fluororesin is generally provided on the base layer or the elastic layer of the film in order to prevent the toner offset phenomenon. .
JP-A-4-44075 JP 2003-045615 A Japanese Patent Laid-Open No. 10-10893 Japanese Patent Laid-Open No. 11-15303 JP-A-7-114276

  In the image heating apparatus using the image heating member provided with the elastic layer for the colorization or the like like the above film, the heat capacity as the image heating member is increased by providing the elastic layer. Since the conductivity is also lowered, it is necessary to apply a larger amount of heat. In particular, in order to ensure high speed and on-demand performance of the image heating apparatus, the image heating apparatus must be quickly raised to a predetermined temperature, and more rapid heating is required.

  However, when such rapid heating is performed, the image heating member may be damaged depending on conditions.

  That is, when the image heating member containing a large amount of moisture in the constituent layer and having a high water content is subjected to rapid heating by applying a large amount of heat as in the startup from the cold state. In some cases, the image heating member is damaged. This is because the blistering of water contained in the image heating member causes blistering on the contact surface between the base layer and the elastic layer, or between the elastic layer and the surface release layer, and the layers are peeled off. This is a heating member damage.

  As the tendency of the image heating member to be damaged by the blistering, the higher the rate of temperature rise, and the more the amount of moisture contained in the image heating member (water content), the more likely it is to bump. Therefore, the possibility of damage to the image heating member is increased.

  The water content of the image heating member varies depending on the material and the use environment. When the image heating member is left for a long period of time in a high temperature and high humidity environment, a material that easily contains moisture is selected as the material for the image heating member. In some cases, the water content of the image heating member increases. For this reason, there are cases where the degree of freedom in material selection is reduced, such as the inability to use inexpensive materials to prevent blistering.

An object of the present invention is to provide an image heating apparatus and a film that prevent damage caused by blistering of the film and does not deteriorate the image quality even when the film (image heating member) having a high water content is rapidly heated. There is to do.

Typical structure of the image heating apparatus according to the present invention for achieving the above object, a base layer, and a surface layer formed of a fluorine resin, a rubber layer formed between said base layer and said surface layer , A heater that contacts the inner surface of the film, and a pressure member that forms a nip portion with the heater via the film, and carries a toner image at the nip portion. In the image heating apparatus for heating while conveying the material, the base layer is a layer that does not have moisture permeability, and the surface layer has a thickness of 5 μm to 50 μm, and the amount of hydrochloric acid permeation after 30 days in the chemical liquid permeation test Is a porous layer of 3.0 × 10 ⁻⁴ (g · cm / cm ² ) or more.

Since the surface release layer has a high water permeability, even when a film with a high water content is rapidly heated, the water contained in the image heating member is appropriately evaporated outside without bumping. be able to. For this reason, damage to the film due to blistering can be prevented, and deterioration in image quality can be prevented.

In addition, since it is not necessary to limit the film to prevent blistering, the degree of freedom of material selection is widened, and for example, it is possible to reduce the cost by using an inexpensive material.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, unless otherwise specified, the scope of the present invention is limited to the specifications of the devices and configurations described in this embodiment, the dimensions, materials, shapes, and relative arrangements of the components. Not intended to do.

(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.

  Next, the charging processing surface is subjected to a scanning exposure process of image information by a laser beam 103 output from a laser optical box (laser scanner) 110. The laser optical box 110 outputs a laser beam 103 that is modulated (on / off) in accordance with a time-series electric digital pixel signal of image information from an image signal generation device such as an image reading device (not shown), and rotates and rotates. The drum surface is scanned and exposed. By this scanning exposure, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 101. 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 and latent image formation are performed on the photosensitive drum 101 for a first color separation component image of a full-color image, for example, a yellow component image. The latent image is developed as a yellow toner image by the operation of the yellow developing device 104Y in the four-color developing device 104. The yellow toner image is transferred onto the surface of the transfer drum 105 at a primary transfer portion T1 which is a contact portion (or proximity portion) between the photosensitive drum 101 and an intermediate transfer drum (hereinafter referred to as transfer drum) 105. The surface of the photosensitive drum 101 after the transfer of the toner image to the surface of the 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 is executed for the second color separation component image (for example, magenta component image, magenta developer 104M is activated) of the full color image. Further, the respective color separation component images of the third color separation component image (for example, the cyan component image and the cyan developing device 104C are operated) and the fourth color separation component image (for example, the black component image and the black developing device 104BK are operated) are sequentially arranged. To be executed. Then, 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 transfer drum 105 to form a color toner image.

  The transfer drum 105 has a middle resistance elastic layer and a high resistance surface layer on a metal drum. The transfer drum 105 is in contact with or close to the photosensitive drum 101 and has a substantially same peripheral speed as the photosensitive drum 101. It is rotationally driven in the direction. Then, a bias potential is applied to the metal drum of the transfer drum 105, and the toner image on the photosensitive drum 101 side is transferred to the surface side of the transfer drum 105 by a potential difference with the photosensitive drum 101.

  The color toner image synthesized and formed on the surface of the transfer drum 105 is transferred to a secondary transfer portion T2 which is a contact nip portion between the transfer drum 105 and the transfer roller 106 from a paper supply portion (not shown) at a predetermined control timing. Are transferred onto the surface of the recording material P fed in.

  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 in the process in which the recording material P is nipped and conveyed by the secondary transfer portion T2, so that the recording material P is transferred from the transfer drum 105 surface side. The combined color toner images are sequentially transferred to the side.

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

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

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

  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. The toner image is transferred to. Then, the recording material is again introduced into the fixing device 100 and undergoes a toner image fixing process on two sides. Thereby, a double-sided image print is output.

  In the multiple image print mode, the recording material P that has been printed on the first image from 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). Then, the second toner image transfer is received on the surface on which the first image has been printed. This recording material is again introduced into the fixing device 100 and undergoes a second toner image fixing process. As a result, a multiple image print is output.

(2) Fixing device 100
The fixing apparatus 100 in this embodiment is basically an image heating apparatus of a film heating system or a pressure roller driving system (tensionless type) disclosed in Japanese Patent Application Laid-Open Nos. 4-44075 to 44083, 4-204800 to 204984, and the like. It is.

  2 is a front model diagram of the fixing device 100 with the intermediate part omitted, FIG. 3 is a longitudinal sectional model diagram with the intermediate part omitted, and FIG. 4 is an enlarged transverse side model diagram.

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

1) Heating assembly 15
The heating assembly 15 includes a cylindrical flexible film (endless belt) 16 as an image heating member, a ceramic heater 17 as a heating body (heating means), a film guide 18, a pressurizing rigid stay 20, and an annular flange member. An assembly such as 25.

  The flexible film (fixing film: hereinafter abbreviated as film) 16 is, for example, a composite in which a base layer, an elastic layer as an intermediate layer, and a surface release layer formed on the outer peripheral surface of the elastic layer are laminated. A layer film can be used. The base layer is, for example, a heat resistant resin layer such as polyimide, polyimide amide, PEEK, PES, or PPS having a thickness of 20 to 100 μm. The elastic layer is, for example, a heat-resistant elastic layer such as silicon rubber or fluorine rubber having a thickness of 50 to 1000 μm. The surface release layer is a layer formed by coating PTFE, PFA, FEP or the like with 5 to 50 μm, for example.

  In this example, a cylindrical polyimide film was used as a base layer, a silicon rubber layer was formed as an elastic layer on the outer peripheral surface, and a PFA was coated on the outer peripheral surface as a surface release layer, and the diameter was 30 mm. . The film 16 will be described in detail later in section (3).

  The heater 17 is a member having a low heat capacity with a direction intersecting the recording material passing direction as a longitudinal direction and rapidly raising the temperature by energization.

  The heater 17 basically includes a heat-resistant / electrically insulating substrate, an energization heating resistor layer formed on the substrate surface, and an insulating material such as a glass coat covering the substrate surface on which the energization heating resistor layer is formed. This is a surface heating type heater having a layer and a feeding electrode portion, and having a low heat capacity as a whole.

  The substrate is, for example, a heat resistant / electrically insulating substrate such as an insulating ceramic such as alumina or aluminum nitride, or a heat resistant resin such as polyimide, PPS, or liquid crystal polymer.

The energization heating resistance layer is formed by, for example, applying Ag / Pd (silver) on a substrate surface by means of screen printing or the like by coating and baking in a linear or narrow strip shape having a thickness of about 10 μm and a width of about 1 to 5 mm. Palladium), RuO ₂ , Ta ₂ N, etc. are resistive layers.

  The power supply electrode portion is a conductive portion that is electrically connected to the energization heating resistor layer and formed on the substrate surface, and to which a voltage is applied from the power supply circuit via the power supply connector.

  The heater surface side is the substrate surface side of the heater 17 on which the energization heating resistor layer and the glass coat insulating layer are formed.

  The surface of the heater 17 is exposed to the outside in a heater fitting groove formed along the length of the film guide 18 at the center on the outer surface side of the film guide 18 with the surface side of the film guide 18 as a film contact sliding surface. Fitted and fixed.

  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 is input to a control circuit unit (not shown). The control circuit unit controls the electric power supplied from the AC power source to the energization heating resistor layer of the heater 17 according to the input temperature detection information by phase, wave number control, etc., and adjusts the temperature of the heater 17 to a predetermined fixing temperature. Control.

  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 in the nip N. You may make it the structure controlled to. That is, 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 the target set temperature, and the energization of the energization heat generation resistance layer of the heater 17 is maintained. The amount can also be controlled.

  The film guide 18 is a heat- and heat-insulating member having a substantially semi-circular cross-sectional shape having a longitudinal direction that intersects the recording material passing direction, and backup of the film 16, pressurization of the nip portion N, heater 17 for supporting the film 17 and transport stability during rotation of the film 16. The film guide 18 is, for example, a molded product of heat resistant resin, and for example, a material having good insulation and heat resistance such as phenol resin, polyimide resin, polyamide resin, polyamideimide resin, PEEK resin, PES resin, and PPS resin is used. . In addition, a material having good insulation and heat resistance such as a fluororesin (PFA, PTFE, FEP, etc.), an LCP (liquid crystal polymer) resin, or a mixed resin thereof is used.

  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 has a core metal 19a provided with an elastic layer 19b such as silicone rubber to reduce the hardness. Both ends of the cored bar 19a are rotatably supported between the front side and the rear side chassis side plate (not shown) of the apparatus. 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. Then, by pressing the pressure springs 22 and 22 between the both ends of the pressure rigid stay 20 and the spring receiving members 21 and 21 on the apparatus chassis side plate side, a pressing force is applied to the pressure rigid stay 20. I am letting. 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 supporting the ceramic heater 17 have a sliding surface that slides on the inner surface of the fixing film 16, and a backup member that supports the fixing film 16. It is.

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. In a state where the rotation speed of the film 16 becomes steady and the temperature of the heater 17 rises to a predetermined temperature, the recording material P carrying the toner t is introduced into the nip portion N with the toner image carrying surface side set to the film 16 side. Is done. The recording material P is brought into close contact with the lower surface of the heater 17 through the film 16 at the nip N, and moves and passes through the nip N together 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.

(3) Film 16
FIG. 5 is a cross-sectional model view showing the layer structure of the film 16 as the image heating member. This film 16 is provided with an elastic layer 2 made of a rubber elastic body and a surface release layer (hereinafter abbreviated as a surface layer) 3 in this order on the outer peripheral surface of a cylindrical base layer 1 mainly composed of polyimide resin. This is a flexible laminated member.

  For adhesion between the base layer 1 and the elastic layer 2 and adhesion between the elastic layer 2 and the surface layer 3, a primer layer (not shown) may be provided between the respective layers.

  The base layer 1 side is the heater sliding surface side (fixing film inner surface side), and the surface layer 3 side is the pressure roller contact surface side (fixing film outer surface side).

a: Base layer 1
Since the base layer 1 mainly composed of polyimide resin satisfies the conditions such as thermal conductivity and mechanical strength required for the film 16, the thickness is preferably in the range of 20 to 100 μm. Furthermore, in order to improve the thermal responsiveness of the film 16, the thermal conductivity of the polyimide film base layer 1 is 0.42 [W / m · K] (1.0 × 10 ⁻³ [cal / cm · sec · ° C.]. ) Or more. Usually, the thermal conductivity of the polyimide resin is 0.25 [W / m · K] (0.6 × 10 ⁻³ [cal / cm · sec · ° C.]) or less. However, the thermal conductivity of the base layer 1 can be increased to the above range by adding, for example, BN, AlN, or SiC as an additive to the resin material.

  On the other hand, a metal sleeve having high thermal conductivity can be used as the base layer. In this case, since the strength can be relatively increased, the thickness can be set thin.

  Thus, by using a heat resistant resin having a low heat capacity or a thin metal film as the base layer 1, the heat capacity of the rotating body can be reduced as compared with the case where a metal roller is used as a base material. Thereby, it becomes possible to reduce the electric power required for start-up, and an on-demand type device can be configured.

b: Elastic layer 2
The material of the elastic layer 2 is, for example, a rubber material such as silicone rubber or fluororubber having a JIS-A hardness of 70 ° or less, more preferably 5 to 40 °, in that it has elastic durability in a high temperature region near the fixing temperature. It is preferable to use In particular, since silicone rubber has a relatively low hardness, it can be filled with a thermally conductive filler while being rubber. Further, by controlling the crosslinking density, it is possible to improve the resilience modulus and compression set rate. Accordingly, silicone rubber is preferable in that it has a high degree of freedom in material design and can be molded by relatively low-cost means such as injection molding and injection molding.

  The thickness of the elastic layer 2 is preferably in the range of 50 μm to 1000 μm, more preferably in the range of 100 μm to 500 μm. When the thickness of the elastic layer 2 is less than 50 μm, it is difficult to impart sufficient elasticity to the film 16 and it is difficult to fix it so as to enclose the toner. For this reason, when the recording material P is OHT, the effect of improving the fixing properties such as transparency, color reproducibility, improvement in gloss unevenness and image roughness cannot be obtained, and uniform fixing cannot be achieved.

  On the other hand, when it is thicker than 1000 μm, the thermal resistance of the film 16 becomes too large, and the thermal responsiveness is impaired.

  The thermal conductivity of the elastic layer 2 is preferably 0.25 [W / m · K] or more. When the thermal conductivity is smaller than 0.25 [W / m · K], the thermal resistance is large and the rise of the film temperature is delayed.

  In general, since the thermal conductivity of silicone rubber is low, the thermal conductivity is increased so that the thermal conductivity is in the above range by adding a filler with high thermal conductivity. Specifically, inorganic powders such as silica, alumina, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, silicon carbide and the like are generally used as the high thermal conductive filler.

c: Surface layer (surface release layer) 3
As the constituent material of the surface layer 3, for example, a fluororesin such as PTFE, PFA, or FEP is suitable, and the moisture permeability is increased by adjusting the manufacturing method, film forming conditions, and the like.

  The thickness of the surface layer 3 is preferably 5 to 50 μm, more preferably 10 to 30 μm. When the thickness of the surface layer 3 is less than 5 μm, the durability is deteriorated (deterioration such as scratches or scraping due to rubbing), and when it is thicker than 50 μm, the thermal response is disadvantageous or substantially This is not preferable because the water permeability is deteriorated.

  As an indicator of moisture permeability, the amount of hydrochloric acid permeation in a chemical solution permeation test can be used as a guideline for material selection.

  The chemical permeation test is a test in which 35% hydrochloric acid is placed in a sealed container sandwiched between 1 mm thick test sheets, and the permeation rate of hydrochloric acid after 30 days at a test temperature of 70 ° C. is large. The moisture permeability is better.

FIG. 6 shows the chemical solution permeation test procedure in the present invention. A is a test sheet (sample sheet). In the present invention, this test sheet A is a sheet having a thickness of 1 mm obtained by adjusting the firing conditions so as to be the same as the surface release layer 3 of the film 16. The thickness of 1 mm is due to the convenience of the measurement test apparatus. And when this test sheet A is sandwiched, “pure water (or air in some cases)” is filled on one side and “35 to 36% hydrochloric acid” is filled on the other side and stored at 70 ° C. for 7 to 4 weeks. Measure the permeation rate of hydrochloric acid. In the present invention, the cumulative permeation amount of hydrochloric acid (μg · cm / cm ² ) is measured after 30 days under the conditions of a test sheet having a thickness of 1 mm, 35% hydrochloric acid and 70 ° C. (Mitsui DuPont) Fluorochemical Co., Ltd. method). The permeation amount of hydrochloric acid is calculated by measuring the Cl concentration on the pure water side by ion chromatography or the like.

The surface layer 3 of the film 16 is preferably one having a large hydrochloric acid permeation amount and a thin film thickness. Specifically, the hydrochloric acid permeation amount is preferably 3.0 × 10 ⁻⁴ (g · cm / cm ² ) or more, and when the film thickness is also taken into consideration, the value of “hydrochloric acid permeation amount / film thickness” is , 300 (g · cm / cm ² · cm) or more is preferable.

When the permeation rate of hydrochloric acid is smaller than 3.0 × 10 ⁻⁴ (g · cm / cm ² ) or when the value of “permeation rate of hydrochloric acid / film thickness” is smaller than 300 (g · cm / cm ² · cm) When a film having a high water content is rapidly heated, the film may be damaged due to blistering.

  The film 16 as described above can be manufactured, 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. Adhere with a proper thickness. Then, it is dried and imidized by heating to form a polyimide film tube-like material as the base layer 1.

  Any method may be used for attaching the polyimide precursor solution to the core with a uniform thickness, but the so-called “cast molding” method, “die coating” method and the like are particularly suitable. For example, after attaching a predetermined amount on the outer peripheral upper portion of the core body by a general method such as dipping or coating, an outer mold having a predetermined clearance is fitted outside the metal core body whose longitudinal direction is held vertically, The outer mold is lowered by its own weight.

  The rubber elastic 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.

  And the surface layer 3 can also be easily formed in accordance with a conventional method such as dispersion coating of fluororesin.

  Then, a film 16 having a three-layer composite layer structure of the base layer 1, the elastic layer 2, and the surface layer 3 is obtained by separating the tube-shaped article having a multilayer structure from the core.

1) Film of Example 1 An aluminum cylindrical core having an outer diameter of 30 mm and a length of 500 mm is immersed in the polyimide precursor solution and pulled up. A ring-shaped outer mold having an inner diameter of 31 mm is dropped by its own weight from the top of the cylindrical core. Thus, a polyimide precursor solution film having a thickness of about 500 μm was cast on the outer surface of the cylindrical core.

  Thereafter, this core was subjected to heat treatment to advance the solvent removal and imide conversion reaction, and a tube-shaped polyimide film (polyimide intermediate) having a thickness of 50 μm and serving as the base layer 1 of the film 16 was formed.

  Next, a silicone rubber composition in which conductive fillers such as alumina, zinc oxide, and magnesium oxide powder are appropriately blended with Hs20 ° LTV silicone rubber (trade name XE15-751, manufactured by Toshiba Silicone Co., Ltd.) is added to the polyimide on the core. The tube surface was coated. The coating layer was heat-treated to form a rubber elastic layer 2 having a thickness of 0.2 mm.

  And the surface of the obtained rubber elastic layer 2 was spray-coated with PFA dispersion (manufactured by DuPont: trade name: Teflon PFA451HP-J) as a fluororesin. This coat layer was baked at 380 ° C. for 10 minutes to form a surface layer (surface release layer) 3 having a thickness of 25 μm.

  Thereafter, the aluminum core was pulled out to obtain a fixing film 16 (sample No. 1) having a multilayer structure.

2) Comparative Example Film As a comparative example film, the amount of filler added to the elastic layer 2 is adjusted to prepare a silicone rubber composition having a different water content (saturation), and the surface layer 3 is a PFA tube having a wall thickness of 25 μm. The thing which coat | covered and baked was prepared. The PFA tube is a product name manufactured by DuPont: Teflon PFA451HP-J. A film having a water content of 0.005 (mg / mm ³ ) was prepared as Sample No. 2, a film having a water content of 0.010 (mg / mm ³ ) It was set to 3.

  In the above sample No. 1, sample no. 2, Sample No. Table 1 shows the permeation amount of hydrochloric acid after 30 days in the surface layer 3 chemical liquid permeation test of each of the sample films 3.

As can be seen from Table 1, the sample No. of the comparative example. 2 and sample no. The film No. 3 had a hydrochloric acid permeation rate of 2.8 × 10 ⁻⁴ (g · cm / cm ² ). On the other hand, sample No. The film No. 1 was 7.5 × 10 ⁻⁴ (g · cm / cm ² ), which was 2.7 times.

  Thus, even if the same kind of material was used, films with different amounts of hydrochloric acid permeation could be obtained depending on the firing conditions and the film forming method.

In the above, sample no. 1 to Sample No. Each film of 3 has the same film thickness. Therefore, regarding the value of the amount of permeated hydrochloric acid / film thickness that is an index of moisture permeability, the film of the comparative example is 112 (g · cm / cm ² · cm), whereas the film of Example 1 is 300 (G · cm / cm ² · cm) and 2.7 times. That is, in Example 1, the water permeability is 2.7 times that of the comparative example.

  In addition, as the firing conditions for the surface layer 3, a method in which the temperature is set lower and the time is set shorter can produce a material with a larger hydrochloric acid permeation amount. This is presumably because a porous film is easily formed depending on the firing conditions.

  About each said sample film, the following boiling tests were done and "blowing" was evaluated. Table 2 shows the value of water absorption in the boiling test and the evaluation result of “water bulge”.

  In addition, as a boiling test, the moisture content of a film is measured by heat-processing for 60 minutes on the conditions of a 110 degreeC / 1.8 atmosphere setting in a pressure kettle, and making a film absorb water. Note that the accelerated test means that the pressure is set higher than the normal pressure in the pressure cooker and moisture is forcibly injected into the sample in comparison with the general water absorption rate test method described in JISK7209-1984. The amount of water absorption can be confirmed. Most of the water absorption is performed by the elastic layer portion.

  The film immediately after that is applied as the film 16 of the fixing device 100 of the image forming apparatus shown in FIG. 1 and FIG. 2, and the rapid heating corresponding to the start-up is performed to confirm the presence of “blowing”. went.

The blister can be easily confirmed visually. When a film under conditions of blistering is rapidly heated as in this example, bubbles due to water vapor gas are generated at the inner interface of the surface release layer and the surface is swollen and visible. And with rotation of a film, the surface release layer part peels and peels off (breaks) etc. can observe visually. The minor blisters determines the gloss unevenness of any image.

In addition, as a water content, the water content at the time of saturation (mg / mm ³ ), which is a weight increase per unit volume, is used as an index. That is, the water content was calculated from (W1-W0) / P, where W1 was the film weight immediately after the boiling test, W0 was the film weight during drying, and P was the volume of the film.

In the comparative example, Sample No. The film No. 2 has a low water content of 0.005 (mg / mm ³ ), so “blowing” does not occur. When the water content was doubled to 0.010 (mg / mm ³ ) as in film 3, “water blistering” occurred. This is because when the moisture content of the film increases, the amount of evaporation (speed) of moisture due to rapid heating cannot catch up with the amount that escapes to the outside through the film of the surface layer 3, and bumping occurs inside the film. This is thought to be due to blistering.

On the other hand, in the film of Example 1, even when the water content was 0.010 (mg / mm ³ ), no blistering occurred and good fixability could be obtained. This is because the surface layer 3 of the film of Example 1 has a large moisture permeability, and therefore, even by rapid heating, the moisture in the film is evaporated to the outside through the film of the surface layer 3 without causing bumping. Because it can. In addition, when a film having a water absorption of 0.020 (mg / mm ³ ) was produced on the same surface layer 3 as in Example 1 and the blistering was evaluated and confirmed in the same manner, no blistering occurred and good fixability was obtained. Could get.

  As described above, by using a layer having a high moisture permeability as the surface layer 3 of the film 16, even when a film having a high water content is rapidly heated, the contained water is evaporated without causing bumping. And film damage due to blistering can be prevented.

  Therefore, a material having a high water absorption rate can also be used, and the degree of freedom in selecting a material as a film is increased. For example, the cost can be reduced by using an inexpensive material.

  Further, as in the comparative example, when a surface layer 3 that has been molded in advance as a tube is used, it is necessary to ensure a certain degree of strength for handling, and thus there is a restriction on the strength of the film itself, the film thickness, and the like. . On the other hand, when the surface layer 3 is formed by coating as in Example 1, it is not necessary to ensure the strength as handling, and it is possible to generate a membrane having a large hydrochloric acid permeation amount. Moreover, since the film thickness of the surface layer 3 can also be reduced, it is possible to set a large hydrochloric acid permeation amount / film thickness as an index of gas permeability.

  On the other hand, as in Example 1, as the resin species of the surface layer 3, a film having a large amount of hydrochloric acid permeation can be easily obtained by controlling the firing conditions by using a cheap PFA resin having a spherical crystal structure. There is also an effect that can be manufactured.

3) Film of Example 2 The film of Example 2 is a film (Sample No. 4) having a firing condition of 350 ° C. for 10 minutes and a film thickness of 50 μm with respect to the surface layer 3 of the film of Example 1, and It is a film (sample No. 5) having a baking condition of 390 ° C. for 20 minutes and a film thickness of 15 μm.

  Table 3 shows the amount of permeated hydrochloric acid of these films, and Table 4 shows the results of water absorption and blister evaluation.

Also in the film of Example 2, it carried out boiling test, where the blister evaluation was performed, without the occurrence of bumping, blister did not occur.

Sample No. When it is desired to increase the film thickness of the surface layer 3 like the film No. 4, the permeation amount of hydrochloric acid is increased. Conversely, even if the amount of hydrochloric acid permeation is relatively small, by controlling the film thickness, the permeation rate of hydrochloric acid / thickness is set to 300 (g · cm / cm ² · cm) or more to ensure moisture permeability. It becomes possible to do.

  Therefore, even when a film having a high water content is heated rapidly, film breakage due to blistering or the like can be prevented.

(Other)
1) In the fixing device of the embodiment, the film 16 as the image heating member is driven by a pressure roller. However, the endless belt-like film is stretched by a driving roller and a tension roller and driven by the driving roller. You can also.

  Moreover, the film 16 as an image heating member can be made into the apparatus structure which makes it the elongate 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 in the nip portion N. For example, it is also possible to adopt a device configuration in which the heating element 17 is disposed on the upstream side of the nip portion N in the film moving direction.

  4) The heating mode of the film 16 is not limited to the internal heating method, but can be an external heating method, or a heating method in which the 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 image heating member is not limited to a film form, and may be a rigid cylindrical member or a roller-like member.

  7) The image heating device of the present invention is not limited to a fixing device, but can be used as an image heating device that is supposed to be worn, an image heating device that reheats a recording material carrying an image, and modifies surface properties such as gloss. .

1 is a schematic configuration diagram of an example of an image forming apparatus according to an embodiment. FIG. 3 is a front model view of the fixing device according to the embodiment with an intermediate portion omitted. It is a longitudinal cross-sectional model figure of the intermediate part omission of the apparatus. It is an expansion transverse side model figure of the device. FIG. 3 is an enlarged cross-sectional model view of a fixing film. It is explanatory drawing of the chemical | medical solution permeation | transmission test point in this invention.

Explanation of symbols

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

Claims (10)

A base layer, and a surface layer formed of a fluorine resin, a rubber layer formed between said base layer and said surface layer, a tubular film having a heater in contact with the inner surface of said film, said film A pressure member that forms a nip portion together with the heater, and an image heating apparatus that heats the recording material carrying a toner image at the nip portion while conveying the recording material,
The base layer is a layer that does not have moisture permeability,
The surface layer is a porous layer having a thickness of 5 μm or more and 50 μm or less and a permeation rate of hydrochloric acid after 30 days in a chemical solution permeation test of 3.0 × 10 ⁻⁴ (g · cm / cm ² ) or more. An image heating apparatus. The image heating apparatus according to claim 1, wherein the base layer is made of metal. The rubber layer is a thermal conductivity of 0.25 [W / m · K] or more silicone rubber composition obtained by adding a thermally conductive filler, water absorption at boiling test is 0.010 (mg / ^mm 3) an apparatus according to claim 1 or 2, characterized in that at least. The image heating apparatus according to any one of claims 1 to 3, wherein the surface layer is a layer formed by coating a fluororesin. The base layer is a layer having a thermal conductivity of 0.42 [W / m · K] or more to which a thermally conductive filler is added, and is a layer formed of a resin having a thickness of 20 μm to 100 μm. The image heating apparatus according to any one of claims 1 to 4 . A cylindrical film having a base layer, a surface layer formed of a fluororesin, and a rubber layer formed between the base layer and the surface layer, the heater being in contact with the base layer of the film; A pressure member that forms a nip portion together with the heater through the film, and a film used in an image heating apparatus that heats a recording material carrying a toner image in the nip portion,
The base layer is a layer that does not have moisture permeability,

The surface layer is a porous layer having a thickness of 5 μm or more and 50 μm or less and a permeation rate of hydrochloric acid after 30 days in a chemical solution permeation test of 3.0 × 10 ⁻⁴ (g · cm / cm ² ) or more. Characteristic film. The film according to claim 6, wherein the base layer is made of metal. The rubber layer is a thermal conductivity of 0.25 [W / m · K] or more silicone rubber composition obtained by adding a thermally conductive filler, water absorption at boiling test is 0.010 (mg / ^mm 3) It is the above, The film of Claim 6 or 7 characterized by the above-mentioned. The film according to any one of claims 6 to 8, wherein the surface layer is a layer formed by coating a fluororesin. The base layer is a layer having a thermal conductivity of 0.42 [W / m · K] or more to which a thermally conductive filler is added, and is a layer formed of a resin having a thickness of 20 μm to 100 μm. The film according to any one of claims 6 to 9 .