JP2016024215A - Nip part formation member, image heating device, and production method of nip part formation member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nip part formation member capable of suppressing electrification on a surface layer of a heating member to achieve both the suppression of a temperature rise at a non-paper passing part and reduction in rise time.SOLUTION: A nip part formation member includes a substrate, an elastic layer formed on the substrate, and a conductive resin surface layer formed on the elastic layer, and forms, by pressure-contacting with a heating member to cause elastic deformation of the elastic layer, a nip part for sandwiching and conveying a sheet carrying a toner image thereon while heating the sheet. The elastic layer includes a needle-like filler 4b1, the needle-like filler is oriented inside the elastic layer so that the heat conductivity in the longitudinal direction of the elastic layer is 6 times or more and 900 times or less the heat conductivity in the thickness direction, and the surface resistance value of the resin surface layer is 10Ω/sq. or more and 10Ω/sq. or less.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a nip portion forming member used in an image heating device mounted on an image forming apparatus, an image heating device using the nip portion forming member, and a method for manufacturing the nip portion forming member.

  There is a heat roller type device as an image heating device (hereinafter referred to as a fixing device) mounted in an image forming apparatus such as an electrophotographic copying machine or a laser beam printer. This apparatus includes, for example, a halogen heater, a fixing roller as a heating member (fixing member) heated by the halogen heater, and a nip portion forming member that forms a nip portion (fixing nip portion) in contact with the fixing roller. And a pressure roller.

  There is also a film heating system. This apparatus includes, for example, a heater having a heating resistor on a ceramic substrate, a fixing film as a heating member that moves while contacting the heater, and a nip that forms a nip portion with the heater via the fixing film. And a pressure roller as a part forming member.

  Each of the above-mentioned heat roller type or film heating type fixing devices transfers a toner image onto a sheet while nipping and conveying a sheet-like recording material (hereinafter referred to as paper or paper) carrying an unfixed toner image. Heat fixing.

  As a problem when trying to adapt such a fixing device to various sizes of large and small sizes, a temperature rise in a non-sheet passing area (non-passing area) when a small size sheet is passed (temperature rise in a non-sheet passing portion) (Non-passing portion temperature rise)). The paper width is a paper dimension in a direction perpendicular to the paper transport direction on the paper surface.

  That is, when a small size paper having a width smaller than that of the largest size paper that can be used in the fixing device is continuously passed through the nip portion formed by the fixing roller and the pressure roller, the length of the nip portion The temperature of the area where the sheet does not contact (non-sheet passing area) rises. This is because in the non-sheet passing area of the nip portion, the heat from the fixing roller is not taken away by the paper or the toner on the sheet, so that the temperature in the non-sheet passing area of the nip portion is only increasing. It is a phenomenon that occurs.

  Such a phenomenon may cause deterioration and deformation of the pressure roller and the fixing roller due to heat. In addition, when a sheet having a width larger than that of a small-size sheet is passed through the nip portion where the temperature of the non-sheet passing area is excessively increased, an area corresponding to the non-sheet passing area on the sheet. The toner may melt excessively, resulting in an offset.

  Such a problem is more likely to occur as the processing speed (process speed) of the printer increases. That is, as the speed increases, the time for the sheet to pass through the nip portion is shortened, so that it is necessary to transmit sufficient heat to the toner image in a short time, and therefore, the temperature of the fixing roller is increased.

  On the other hand, speeding up of the first print time and energy saving are progressing, and accordingly, it is desired to reduce power consumption and particularly to shorten the heating start-up time of the fixing device (hereinafter referred to as the start-up time). Therefore, in recent years, the elastic layer of the pressure roller is an elastic layer in which a gap is disposed, that is, a porous elastic layer, thereby reducing the heat capacity and the thermal conductivity. By making the pressure roller have a low heat capacity and low thermal conductivity, the amount of heat taken away from the heating element by the pressure roller at the start of the operation of the fixing device is kept small, and the temperature rise rate of the fixing roller and fixing film in contact with the pressure roller The idea is to improve

  The following three methods have been proposed as a method for forming the gap. In Patent Document 1, a void is formed by mixing an uncrosslinked silicone rubber with a foaming agent and foaming and curing. In Patent Document 2, a hollow filler is mixed in advance with uncrosslinked silicone rubber to form voids after molding and crosslinking. In Patent Document 3, a water-containing material in which water is contained in a water-absorbing polymer is dispersed in uncrosslinked silicone rubber and dehydrated during crosslinking to form voids.

  However, the reduction of the heat capacity and the thermal conductivity of the pressure roller is in the direction of accelerating the temperature rise of the non-sheet passing portion during continuous passing of the small size paper described above. That is, it can be said that it is difficult to achieve both suppression of excessive temperature rise in the nip portion and reduction in heating start-up time of the nip portion.

  Here, in Patent Document 4, a high heat conductive rubber composite in which a fibrous filler is blended in the elastic layer of the pressure roller is used, and the non-sheet passing portion is made high in the roller rotation axis direction (longitudinal direction). I am trying to suppress the temperature rise.

  Further, it is described that a rise time can be shortened by providing a porous elastic layer below the elastic layer and reducing the thermal conductivity in the elastic layer thickness direction.

JP 2008-150552 A JP 2001-265147 A JP 2002-114860 A JP 2002-351243 A

  However, in the pressure roller described in Patent Document 4, the high thermal conductive rubber composite and the heat insulating rubber are formed in separate steps, and the manufacturing process may be complicated.

  Also, when the surface of the heating member comes into contact with the paper and is peeled after pressure is applied, the static electricity is generated on the surface of the heating member as the pressure is higher and the peeling speed is higher. That is, in order to achieve high productivity, the pressure contact force is increased, and when the transport speed is high, a large static electricity is generated on the surface of the heating member, and when the trailing edge of the paper is peeled off from the heating member, An excessively charged state occurs on the surface layer of the heating member at the peeled position.

  When such an excessively charged state occurs on the surface of the heating member, an unfixed toner image is formed on the surface and the sheet conveyed to the fixing device enters the nip as follows. May occur. That is, a phenomenon occurs in which the toner that is electrostatically adhered to the paper receives an external force due to excessive charging of the surface layer of the heating member, and the toner position is shifted. Due to this phenomenon, there is a problem that line-like image disturbance occurs in the surface position of the heating member located at the rear end of the preceding paper, particularly in an intermediate density image (hereinafter referred to as peeling discharge trace).

  Therefore, there is a need for a nip portion forming member that simplifies the manufacturing process, suppresses charging of the surface layer of the heating member, suppresses non-passage portion temperature rise (non-paper passage portion temperature rise) as much as possible, and shortens the rise time. ing.

  The present invention provides a nip portion forming member that can meet this demand. An image heating apparatus using the nip portion forming member and a method for manufacturing the nip portion forming member are provided.

In order to achieve the above object, a typical configuration of the nip portion forming member according to the present invention includes a base, an elastic layer formed on the base, and a conductive resin surface layer formed on the elastic layer. A nip portion forming member for forming a nip portion for holding and heating a sheet-like recording material carrying a toner image by elastic deformation of the elastic layer by pressure contact with the heating member, The layer includes an acicular filler, and the acicular filler includes a layer of the elastic layer such that the thermal conductivity in the longitudinal direction of the elastic layer is 6 to 900 times the thermal conductivity in the thickness direction. The resin surface layer has a surface resistance value of 10 ⁵ Ω / □ or more and 10 ¹² Ω / □ or less.

  In order to achieve the above object, another typical structure of the nip portion forming member according to the present invention includes a base, an elastic layer formed on the base, and a conductive layer formed on the elastic layer. A nip portion forming member that forms a nip portion that holds and heats a sheet-like recording material carrying a toner image by elastically deforming the elastic layer by pressure contact with the heating member. The elastic layer includes a needle-like filler, and the needle-like filler has a thermal conductivity in the longitudinal direction of the elastic layer of 6 times or more and 900 times or less of the thermal conductivity in the thickness direction. The elastic layer is oriented in the layer, and the resin surface layer has a thickness of 5 μm or more and less than 20 μm.

  In order to achieve the above object, a typical configuration of the image heating apparatus according to the present invention is to sandwich and convey a heating member and a recording material carrying a toner image that is elastically deformed by pressure contact with the heating member. An nip portion forming member for forming a nip portion to be heated, wherein the nip portion forming member is the nip portion forming member.

Further, a typical configuration of the method for producing a nip portion forming member according to the present invention for achieving the above object is the method for producing the above nip portion forming member,
(1) A liquid composition for forming an elastic layer containing uncrosslinked rubber, acicular filler dispersed in the rubber, and a water-containing material is flowed in a direction along the length of the substrate to form a layer of the liquid composition Forming on the substrate;
(2) a step of crosslinking the rubber in the layer of the liquid composition while retaining moisture in the water-containing material;
(3) a step of evaporating water in the water-containing material from a layer formed by crosslinking the rubber to form a porous elastic layer;
It is characterized by having.

  According to the nip portion forming member and the image heating apparatus of the present invention, charging of the surface layer of the heating member can be suppressed, and the temperature rise of the non-sheet passing portion can be suppressed and the rise time can be shortened. Moreover, according to the manufacturing method of the nip part formation member of this invention, a manufacturing process can be simplified.

Schematic cross-sectional view showing a schematic configuration of a fixing device in an embodiment Perspective view of pressure roller Schematic diagram of needle filler Enlarged perspective view of a cut-out sample of the elastic layer of the pressure roller of FIG. (A) is an enlarged view of the a section of the cutout sample of FIG. 4, (b) is an enlarged view of the b section of the cutout sample of FIG. Explanatory drawing of thermal conductivity measurement of cut sample of elastic layer Schematic configuration diagram of an example of an image forming apparatus Illustration of mold configuration Form of injection hole provided on one end side piece Explanatory drawing of how to arrange roller base for mold Explanatory drawing of casting process Schematic diagram of the state in which the fluororesin tube is placed on the inner surface (formation surface) of the mold in advance Schematic diagram of non-rotating nip forming member

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1) Image Forming Unit FIG. 7 is a schematic cross-sectional view showing a schematic configuration of an example of an image forming apparatus in which the image heating apparatus according to the present invention is mounted as the fixing device A.

  The image forming apparatus 21 is an electrophotographic laser printer, and includes a photosensitive drum 22 as an image carrier that carries a latent image. The photosensitive drum 22 is rotationally driven in the clockwise direction indicated by the arrow at a predetermined speed, and the outer surface thereof is uniformly charged to a predetermined polarity and potential by the charger 23. Laser scanning exposure 25 of image information is performed on the uniformly charged surface by a laser scanner (optical device) 24. As a result, an electrostatic latent image of the scanned image information is formed on the surface of the photosensitive drum 22.

  The electrostatic latent image is developed as a toner image by the developing device 26. The toner image is transferred to a sheet-like recording material (hereinafter referred to as paper or paper) P introduced into the transfer portion 35 in the transfer portion 35 that is a contact portion between the photosensitive drum 22 and the transfer roller 27. Are sequentially transferred.

  The sheets P are stacked and stored in a lower sheet feeding cassette 29 in the image forming apparatus main body. When the paper feed roller 30 is driven at a predetermined paper feed timing, the sheet P in the paper feed cassette 29 is separated and fed one by one, and reaches the registration roller pair 32 through the transport path 31a. The registration roller pair 32 receives the leading end of the paper P and corrects the skew of the paper P. Further, the toner image on the photosensitive drum 22 is aligned with the timing when the leading end of the sheet P reaches the transfer unit 35 when the leading end of the toner image on the photosensitive drum 22 reaches the transfer unit 35. In synchronization, the paper P is fed to the transfer unit 35.

  The sheet P that has passed through the transfer unit 35 is separated from the surface of the photosensitive drum 22 and is conveyed to the fixing device A. The fixing device A fixes the unfixed toner image on the paper P as a fixed image on the paper surface by heating and pressing. Then, the sheet P is discharged and stacked on the discharge tray 34 on the upper surface of the image forming apparatus main body by the discharge roller pair 33 through the conveyance path 31b. Further, the surface of the photosensitive drum 22 after the paper separation is cleaned by removing residual deposits such as transfer residual toner by the cleaning device 28, and is repeatedly used for image formation.

(2) Fixing device A
FIG. 1 is a schematic cross-sectional view of the fixing device A. The fixing device A is a film (belt) heating type device, and its schematic configuration will be described below. In the following description, regarding the fixing device and the members constituting the fixing device, the axial direction is a direction orthogonal to the paper transport direction on the surface of the paper. The length is an axial dimension.

  Reference numeral 1 denotes a laterally long film guide member having a substantially semicircular arc shape and a saddle-shaped cross section and having a vertical direction in the drawing as a longitudinal direction, and is composed of, for example, a heat resistant resin such as PPS (polyphenylene sulfite) or a liquid crystal polymer. Yes. Reference numeral 2 denotes an elongated plate-like heater as a heating body that is housed and held in a groove 1 a formed along the longitudinal direction at the approximate center of the lower surface of the film guide member 1. Reference numeral 3 denotes an endless (cylindrical) fixing film (fixing belt: hereinafter also referred to as a film) as a heating member. The fixing film 3 is loosely fitted on the film guide member 1 on which the heater 2 is mounted.

  The heater 2 has a configuration in which a heating resistor is provided on a ceramic substrate. A heater 2 shown in FIG. 1 includes a thin or thin heater substrate 2a made of alumina or the like, and a linear or narrow strip Ag / Pd formed on the surface side (film sliding surface side) along the length. And an energization heating element (heating resistor) 2b. The heater 2 has a thin surface protective layer 2c such as a glass layer that covers and protects the energization heating element 2b. A temperature detecting element 2d such as a thermistor is in contact with the back side of the heater substrate 2a.

  The heater 2 is controlled to maintain a predetermined fixing temperature (target temperature) by a power control system (not shown) including a temperature detecting element 2d after the temperature is rapidly raised by supplying power to the energization heating element 2b.

  The fixing film 3 has a surface layer coated on the surface of a base film having a total thickness of 100 μm or less, preferably 20 μm or more and 60 μm or less in order to reduce the heat capacity and improve the quick start property of the fixing device A. For example, a composite layer film.

  As the material of the base film, resin materials such as PI (polyimide), PAI (polyamideimide), PEEK (polyetheretherketone), and PES (polyethersulfone), and metal materials such as SUS and Ni are used. As the material for the surface layer, a fluororesin material such as PTFE polytetrafluoroethylene) · PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether) · FEP (tetrafluoroethylene-perfluoroalkyl vinyl ether) is used.

  Reference numeral 4 denotes a pressure roller having elasticity as a nip portion forming member, and sandwiches and conveys a paper P carrying a toner image (also referred to as a toner image) T by being elastically deformed by pressure contact with the fixing film 3 as a heating member. A nip portion (fixing nip portion) N is formed.

  The pressure roller 4 includes a base (shaft core, cored bar) 4a made of iron or aluminum, an elastic layer 4b made of silicone rubber, and a release layer (resin surface layer) 4c such as a conductive resin tube. Have. In the fixing device A shown in FIG. 1, the heater 2 and the pressure roller 4 are in pressure contact with each other with a predetermined pressure with the fixing film 3 sandwiched in parallel in the longitudinal direction. As a result, a nip N having a predetermined width necessary for heating and fixing the toner image T is formed between the fixing film 3 and the pressure roller 4 in the paper transport direction (recording material transport direction) Q.

  The pressing contact between the fixing film 3 and the pressure roller 4 can be achieved by pressing the fixing roller 3 to the fixing film 3 side with a predetermined pressing force by a pressing mechanism (not shown). 4 may be used. Alternatively, the fixing film 3 side and the pressure roller 4 may be pressed against each other with a predetermined pressure.

  In the fixing device A shown in FIG. 1, the driving force of a driving source (motor) M is transmitted to the pressure roller 4 through a power transmission mechanism such as a gear (not shown), and the pressure roller 4 is It is rotationally driven in the counterclockwise direction indicated by arrow r2 at the peripheral speed. When the pressure roller 4 is driven to rotate, the inner surface of the fixing film 3 is in close contact with the surface of the surface protective layer 2c of the heater 2 in the nip portion N and slides around the outer periphery of the film guide member 1 with an arrow r1. It rotates following the rotation of the pressure roller 4 in the clockwise direction. A neutralizing brush 15 is in contact with the surface of the resin tube 4 c of the pressure roller 4.

  When the pressure roller 4 is driven to rotate, the fixing film 3 is driven to rotate, and the heater 2 is energized to increase the temperature to a predetermined temperature, and the unfixed toner image in the nip portion N is obtained. A paper P carrying T is introduced. The fixing film 3 faces the toner image carrying surface side (paper surface side) of the paper P, and the pressure roller 4 faces the opposite surface side (paper back side). While the sheet P is nipped and conveyed by the nip portion N, while passing through the nip portion N, heat is supplied from the fixing film 3 heated by the heater 2, and the pressure of the nip portion N is received. By this heating and pressurization, the unfixed toner image T is fixed on the sheet P surface as a fixed image.

(3) Pressure roller 4
FIG. 2 is an overhead model diagram (appearance perspective model diagram) of the pressure roller 4 shown in FIG. In the following, the circumferential direction (paper transport direction) of the pressure roller 4 is the “x” direction, the longitudinal direction of the pressure roller 4 (hereinafter referred to as the axial direction) is the “y” direction, and the thickness of the constituent layers of the pressure roller 4 The direction (layer thickness direction) is represented as the “z” direction.

  L4 is the length (width) dimension of the pressure roller 4. In this example, the pressure roller length L4 is 320 mm. Wmax is the width of the maximum width sheet that can be introduced into the nip portion N (fixing apparatus A). In this example, the maximum width size Wmax is a so-called center reference and the lateral feed width is 297 mm.

  The outer diameter of the base 4a is, for example, 4 mm to 80 mm. Reference numerals 4a-1 and 4a-2 denote small-diameter shafts disposed concentrically with the base body 4a on one end side and the other end side in the longitudinal direction of the base body 4a. The small-diameter shaft portions 4a-1 and 4a-2 are portions that are rotatably supported by fixed portions (not shown) such as a frame of the fixing device A, respectively.

  The elastic layer 4b has needle-like fillers 4b1 oriented in the axial direction y of the pressure roller 4 and voids (porous). The elastic layer 4b will be described in more detail with reference to FIGS.

  FIG. 3 is an enlarged perspective view of the needle-like filler 4b1 having a diameter D and a length L. The acicular filler 4b1 exists in the elastic layer 4b so as to be oriented in the axial direction y. In addition, the physical property etc. of the acicular filler 4b1 are mentioned later.

  FIG. 4 is an enlarged perspective view of a cut sample 4bs obtained by cutting the elastic layer 4b of FIG. The cut sample 4bs is cut along the axial direction y and the circumferential direction x as shown in FIG. If the circumferential cross section (a cross section) and the axial cross section (b cross section) of the cut sample 4bs are observed, the cross section with the diameter D of the acicular filler 4b1 is mainly the cross section a as shown in FIG. I can observe. In the b cross section, as shown in FIG. 5B, the length L portion of the needle-like filler 4b1 can be mainly observed. Moreover, the space | gap 4b2 distributed uniformly can be observed in any of (a) and (b) of FIG.

  Next, as a characteristic expression of the elastic layer 4b in FIG. 1, there are a base polymer, a needle-like filler, a void, and a conductive fluororesin surface layer 4c. The following will be described in order.

<Base polymer>
The base polymer of the elastic layer 4b is obtained by crosslinking and curing an addition-curable liquid silicone rubber. The addition-curable liquid silicone rubber is an uncrosslinked silicone rubber having an organopolysiloxane (A) having an unsaturated bond such as a vinyl group and an organopolysiloxane (B) having a Si—H bond (hydride). Crosslinking and hardening proceeds by the addition reaction of Si—H to an unsaturated bond such as a vinyl group by heating or the like. As a catalyst for promoting the reaction, (A) generally contains a platinum compound. This addition-curable liquid silicone rubber can adjust the fluidity within a range that does not impair the object of the present invention.

<Needle filler 4b1>
The needle-like (long and narrow fiber-shaped) filler 4b1 has heat conduction anisotropy (characteristic that the heat conduction in the major axis direction (length direction) of the needle-like filler is higher) that easily conducts heat in the oriented direction. ing. The needle shape refers to a shape having a length in only one direction compared to the other direction, and the shape can be represented mainly by a short axis diameter and a long axis length. The minor axis diameter (average) is not particularly limited, but those of 5 to 15 μm can be used relatively easily. The major axis length (average) is preferably 0.05 to 5 mm. More preferably, it is 0.05 to 1.0 mm.

  As shown in FIG. 3, the needle-like filler 4b1 can use a material having a large ratio of the length L to the diameter D, that is, a high aspect ratio. The shape of the bottom surface of the needle-like filler may be circular or square, and can be applied as long as the material is oriented by the molding method described later. An example of such a material is pitch-based carbon fiber.

  By including pitch-based carbon fibers having a thermal conductivity λ of 500 W / (m · K) or more, an effective pressure roller 4 can be obtained. The characteristics of the present invention as an electrophotographic member can be suitably implemented.

  Furthermore, when this pitch-based carbon fiber is needle-shaped, a more suitable pressure roller 4 can be obtained. As a more specific shape, the needle-like pitch-based carbon fiber has a diameter D (average diameter (short axis diameter)) of 5 to 11 μm and a length L (average length (major axis length) in FIG. 3. ) Is about 100 μm to 1000 μm, and is easily industrially available.

  The content of the needle-shaped filler 4b1 in the elastic layer 4b is obtained in order to obtain the effect of suppressing the temperature rise of the non-sheet passing portion without lowering the thermal conductivity in the axial direction y of the pressure roller 4, and the elastic layer 4b. In order not to make it difficult to form, it is preferable to contain 5 volume% or more and 40 volume% or less.

  In addition, content, average length, and heat conductivity of said needle-like filler 4b1 can be calculated | required as follows. The method for measuring the content (volume%) of the needle-like filler 4b1 in the elastic layer 4b is as follows. First, an arbitrary part of the elastic layer 4b is cut out, and the volume at 25 ° C. is measured by an immersion specific gravity measuring device (SGM-6, METTLER). (Hereinafter, this volume is referred to as Vall).

  Next, the silicone rubber component is heated by heating the evaluation sample subjected to volume measurement at 700 ° C. for 1 hour in a nitrogen gas atmosphere using a thermogravimetric measurement device (trade name: TGA851e / SDTA, manufactured by METTLER TOLEDO). Disassemble and remove. When an inorganic filler is contained in the elastic layer 4b in addition to the acicular filler, the residue after the decomposition is in a state where the acicular filler and the inorganic filler are mixed.

  In this state, the volume at 25 ° C. is measured with a dry automatic densimeter (trade name: Accupic 1330-1, manufactured by Shimadzu Corporation) (hereinafter, this volume is referred to as Va). Thereafter, the needle-like filler is thermally decomposed and removed by heating at 700 ° C. for 1 hour in an air atmosphere. The volume of the remaining inorganic filler at 25 ° C. is measured with a dry automatic densimeter (trade name: Accupic 1330-1, manufactured by Shimadzu Corporation) (hereinafter, this volume is referred to as Vb). Based on these values, the weight of the needle filler can be obtained from the following equation.

Volume (volume%) of acicular filler = {(Va−Vb) / Val} × 100
The average length of the acicular filler can be determined by a general method by microscopic observation of the acicular filler after the silicone rubber component is removed by heating.

  The thermal conductivity of the needle-like filler can be obtained from the thermal diffusivity, constant pressure specific heat, and density by the following formula. Here, the thermal diffusivity is measured by a laser flash method thermal constant measuring apparatus (trade name: TC-7000, manufactured by ULVAC-RIKO Inc.). The constant-pressure specific heat is determined by a differential scanning calorimeter (trade name: DSC823e, manufactured by METTLER TOLEDO). The density is determined by a dry automatic densimeter (trade name: Accupic 1330-1, manufactured by Shimadzu Corporation).

Thermal conductivity = thermal diffusivity × constant pressure specific heat × density In addition, the average value for a total of five cut samples is adopted as the content, average length, and thermal conductivity of the needle-shaped filler of this example.

<Gap 4b2>
In the elastic layer 4b, oriented needle fillers 4b1 and voids 4b2 coexist. Depending on the foaming agent and the void forming means such as hollow particles, the orientation of the needle-like filler 4b1 may be inhibited. Since the orientation state of the needle-like filler 4b1 dominates the thermal conductivity in the axial direction y, if the orientation is hindered, the effect of suppressing the temperature rise of the non-sheet passing portion is undesirably reduced.

On the other hand, when voids are formed using a water-containing material, it is possible to reduce the alignment inhibition of the coexisting acicular filler. Although it is not clear about the mechanism that can achieve both the orientation in the axial direction y of the needle-like filler 4b1 and the formation of voids, there is no hard shell such as the hollow particles, and the diameter of the dispersed hydrogel can be reduced. It is considered that there is little influence on the orientation inhibition of the needle-shaped filler at the time. In view of strength and image quality, the void diameter is preferably less than 20 μm.

  The porosity of the elastic layer 4b is preferably 20% by volume or more and 70% by volume or less in order to obtain the expected rise time shortening effect and for ease of molding. The higher the porosity, the shorter the rise time, and more preferably 30 volume% or more and 70 volume% or less.

  The porosity of the region up to a depth of 500 μm from the surface of the elastic layer 4b can be obtained by the following equation.

First, a region from the surface of the elastic layer 4b to a depth of 500 μm was cut with an arbitrary surface using a razor. The volume at 25 ° C. is measured with an immersion specific gravity measuring device (SGM-6, manufactured by METTLER TOLEDO Co., Ltd.) (Val above). Next, the evaluation sample subjected to volume measurement is heated at 700 ° C. for 1 hour in a nitrogen gas atmosphere using a thermogravimetric measurement apparatus (trade name: TGA851e / SDTA, manufactured by METTLER TOLEDO). Thereby, the silicone rubber component is decomposed and removed (hereinafter, the weight loss at this time is referred to as Mp).
When an inorganic filler is contained in the elastic layer 4b in addition to the acicular filler, the residue after the decomposition is in a state where the acicular filler and the inorganic filler are mixed.

In this state, the volume at 25 ° C. is measured with a dry automatic densimeter (trade name: Accupic 1330-1, manufactured by Shimadzu Corporation) (Va). Based on these values, the void amount can be obtained from the following equation. The density of the silicone polymer was calculated as 0.97 g / cm ³ (hereinafter, this density is referred to as ρp).

Void volume (% by volume) = [{(Val− (Mp × ρp + Va)} / Val] × 100
The void amount as the elastic layer 4b can be measured in the same manner as described above by cutting the elastic layer 4b from an arbitrary surface. In addition, the average value about a total of five cut samples is employ | adopted for the space | gap amount of a present Example.

<Conductive fluororesin>
The release layer 4c around the elastic layer 4b is mainly made of fluororesin as a heat-resistant polymer compound. In general, tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), or the like is used. Of the materials listed above, PFA is preferable from the viewpoint of moldability and toner releasability.

  As the conductive fluororesin of the release layer 4c, a conductive PFA tube manufactured from C9058 (manufactured by Mitsui Dupont Fluorochemical), C9068 (manufactured by Mitsui Dupont Fluorochemical), AP230AS (manufactured by Daikin Industries, Ltd.) or the like may be used. . Also, it is preferable to apply 350-J of Mitsui / DuPont Fluorochemical Co., Ltd. with PFA coating by spray coating.

  Further, in order to eliminate the charge state of the surface layer of the fixing film 3 that causes the peeling discharge trace (to eliminate the charge), the release layer 4c is made of a conductive fluororesin. Conductive fillers (conductive carbon) such as carbon black are dispersed in the materials listed above.

The surface resistance is preferably 10 ⁵ Ω / □ or more and 10 ¹² Ω / □ or less. If the content of the conductive filler is too large, the releasability is lowered. Therefore, the surface resistance value is desirably 10 ⁵ Ω / □ or more. When the surface resistance value exceeds 10 ¹² Ω / □, it becomes difficult to eliminate the electric resistance state of the surface layer of the fixing film 3, and a peeling discharge trace is generated.

Note that an ionic conductive agent may be added as a method of setting the surface resistance value of the fluororesin of the release layer 4c to 10 ⁵ Ω / □ or more and 10 ¹² Ω / □ or less.

  The surface resistance value is obtained by cutting out the conductive release layer (resin surface layer) 4c from the pressure roller 4 and cutting out from the release layer 4c at 40 mm × 30 mm so that the axial direction y is long. And using a high resistance resistivity meter (trade name: Hiresta UP MCP-HT450 type, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and a UA probe, the longitudinal direction of the cut-off release layer 4c is measured for 10 seconds by applying DC500V. did. The measurement environment is 23 ± 3 ° C. and 50 ± 5% RH. In addition, the average value about a total of five samples is employ | adopted for the surface resistance value of a present Example.

(4) Manufacturing Method of Pressure Roller 4 (4-1) Liquid Composition Formulation The needle-shaped filler 4b1 and the water-containing material are blended with uncrosslinked addition-curable liquid silicone rubber. Formulation is possible by weighing a predetermined amount of uncrosslinked addition-curing liquid silicone rubber, needle-like filler 4b1 and water-containing material, and dispersing the mixture by a known filler mixing and stirring means such as a planetary universal mixing and stirring machine. is there.

(4-2) Molding of Elastic Layer 4b Using Liquid Composition (4-2-1) Mold FIG. 8 (a) shows the mold 11 used for casting production of the pressure roller 4 in this embodiment. It is a disassembled perspective view. (B) is a longitudinal sectional view of the hollow mold 5, the one end side piece mold 6 and the other end side piece mold 7 constituting the mold 11. The mold 11 includes a hollow mold (hollow cylindrical mold, pipe-shaped cylinder) 5 having a columnar molding space (hereinafter referred to as a cavity) 53, and one end side opening 51 of the hollow mold 5. It has the one end side piece type 6 and the other end side piece type 7 which are respectively attached to the other end side opening 52.

  The one-end piece 6 is a piece for injecting liquid rubber into the cavity 53 of the hollow mold 5. The other end-side piece 7 is a piece for discharging the air pushed out from the cavity 53 as the liquid rubber is injected into the cavity 53.

  9A is an inner view (end view on the cavity side) of the one-end piece 6 and FIG. 9B is an outer view (end view on the side opposite to the cavity side). A central hole 6c serving as a base body holding portion into which the small-diameter shaft portion 4a-1 on one end side of the base body 4a is inserted is provided in the central portion on the inner surface side of the one end piece 6. Further, a circumferential hole (sinus, recess) 6a is provided on the outer surface side. A plurality of liquid rubber mixture injection holes 6b extending from the outer surface side to the inner surface side are formed in the circumferential hole 6a along the circumference.

  Further, a central hole 7c as a substrate holding portion into which the small-diameter shaft portion 4a-2 on the other end side of the substrate 4a is inserted is provided in the inner surface central portion (end surface central portion on the cavity side) of the other end side piece mold 7. Yes. A plurality of exhaust holes 7b extending from the inner surface side to the outer surface side are formed.

  The one-end-side piece 6 is fitted into the one-end-side opening 51 of the hollow mold 5 with the inner surface first, and the inner peripheral edge of the inner-edge is abutted against and received by the annular step 51a on the inner peripheral surface of the opening. Until the hollow mold 5 is fully inserted. The other end piece mold 7 is fitted to the other end side opening 52 of the hollow mold 5 with the inner surface side first, and the inner peripheral edge of the circular peripheral edge projects into the annular step 52a on the inner peripheral surface of the opening. The hollow mold 5 is mounted on the other end side by being sufficiently inserted until it is received.

(4-2-2) Placement of Base on Mold A base 4a was previously subjected to a known primer treatment on the portion where the elastic layer 4b is formed. When the elastic layer 4b and the substrate 4a are adhered to each other without performing the primer treatment, the primer may not be used.

  As shown in FIG. 10A, the one end piece 6 is attached to the one end opening 51 of the hollow mold 5. Next, as shown in (b), the base body 4a is inserted from the other end side opening 52 of the hollow mold 5 with the small diameter shaft portion 4a-1 on the one end side first, and the one end piece type is formed. The small-diameter shaft portion 4a-1 is inserted into and supported by the central hole 6c on the inner surface side. Next, as shown in (c), the other end piece die 7 is inserted into the other end side opening 52 of the hollow mold 5, and the small diameter shaft portion 4a on the other end side of the base 4a is inserted into the central hole 7c on the inner surface side. -2 is inserted and supported.

  Thus, the base 4a is supported by the small-diameter shaft portions 4a-1 and 4a-2 on one end side and the other end side thereof in the center holes 6c and 7c of the one end side piece 6 and the other end piece 7 respectively. The position is determined concentrically and held in the center of the column of the columnar cavity 53 of the mold 5. A rubber elastic layer 4b having a predetermined thickness is provided between the cylindrical molding surface (inner peripheral surface) 53a of the cylindrical cavity 53 and the outer surface (outer peripheral surface) 4a-3 of the base body 4a on the outer periphery of the base body 4a. A gap 8 for casting is formed.

  In addition, installation of the base 4a with respect to the cavity 53 of the mold 11 is not limited to the above procedure. The hollow mold 5, the base 4a, the one end side piece mold 6, and the other end side piece mold 7 may be finally assembled as shown in FIG.

(4-2-3) Liquid Composition Layer Molding Step As shown in FIG. 11, the mold 11 having the base 4a installed in the cavity 53 as shown in FIG. With the piece 7 as the upper side, it is pressed and fixed in a vertical posture between the opposed lower jig 12 and upper jig 13 and held. One end side piece type (hereinafter referred to as a lower piece type) 6 side of the mold 11 is received and received in a receiving hole 12 a of the lower jig 12. The other end piece type (hereinafter referred to as the upper piece type) 7 side of the mold 11 is fitted into the receiving hole 13 a of the upper jig 13 and received.

  That is, the mold 11 has the lower jig 12 and the upper jig 13 in a posture in which the cylindrical axis of the cylindrical cavity 53 is oriented vertically and the side on which the injection hole 6b is disposed is the lower side. The casting process is performed while being fixedly held between the two. A liquid composition inlet 12b is formed at the center of the receiving hole 12a of the lower jig 12. A liquid composition supply pipe 14a of an external liquid composition supply device 14 is connected to the injection port 12b. An exhaust port 13 b is formed in the center of the receiving hole 13 a of the upper jig 13.

  When the supply device 14 is driven, the liquid composition of the item (1) enters the receiving hole 12a from the inlet 12b of the lower jig 12 through the supply pipe 14a, and the outer surface of the receiving hole 12a and the lower piece mold 6 The space portion formed by the circumferential hole 6a on the side is filled. As the liquid composition is subsequently supplied, the filled liquid composition flows from the outer surface side to the inner surface side of the lower piece mold 6 through a plurality of injection holes 6b formed along the circumference of the circumferential hole 6a. . And it inject | pours with respect to the clearance gap 8 formed between the cylindrical molding surface 53a of the cavity 53, and the outer surface 4a-3 of the base | substrate 4a.

  As the liquid composition is further supplied, the liquid composition is injected into the gap 8 from the bottom to the top. The air present in the gap 8 is pushed up from the bottom to the top in accordance with the injection of the liquid composition into the gap 8 from the bottom to the top. It goes out of the mold 11 through the exhaust port 13 b of the jig 13.

  The liquid composition is injected from the respective injection holes 6 b of the lower piece mold 6 into the gap 8 on the average in the circumferential direction of the gap 8. In addition, the base body 4a is concentrically fixed to the cylindrical central portion of the cavity 53 by the upper and lower piece molds 6 and 7, and the base body 4a does not move when the liquid composition is injected, and the uneven thickness is reduced. The gap 8 can be filled with the liquid composition without excess or deficiency.

  As described above, the liquid composition is cast into the mold on which the substrate 4a is disposed while flowing in the axial direction y and the circumferential direction x. Due to the casting flow of the liquid composition, most of the needle-like fillers 4b1 included in the liquid composition are oriented in the axial direction y of the substrate 4a, that is, in the longitudinal direction of the pressure roller 4 according to the flow of the liquid composition. This effectively increases the thermal conductivity in the axial direction y and the circumferential direction x of the pressure roller 4 (hereinafter, the axial direction y and the circumferential direction x are also referred to as the surface direction xy of the pressure roller 4).

  The liquid composition is injected into the mold 11 at least until the gap 8 is sufficiently filled with the liquid composition. The exhaust hole 7b of the upper piece 7 need not be sufficiently filled with the liquid composition. Note that the liquid composition layer forming method is not limited to the above method as long as the layer can be formed while applying a flow to the liquid composition in the axial direction y.

(4-2-4) Silicone rubber component cross-linking curing step After casting the liquid composition (after completion of the casting step), the mold 11 is removed from the upper and lower jigs 12 and 13. At this time, the outer openings of the lower piece mold 6 and the upper piece mold 7 are attached by attaching a blind plate or the like so that the liquid composition in the mold 11 does not flow out from the outer openings of the lower piece mold 6 and the upper piece mold 7. Seal. And in the state which sealed the metal mold | die 11, it heat-processes for 5 minutes-120 minutes at the temperature below the boiling point of water, and a silicone rubber component is bridge | crosslinked and hardened. As heat processing temperature, 60-90 degreeC is desirable. Since it is hermetically sealed, the silicone rubber component can be crosslinked and cured while retaining moisture in the water-containing material.

(4-2-5) Demolding Step After appropriately cooling the mold 11 with water or air, the substrate 4a on which the liquid composition layer after crosslinking and curing is laminated is demolded.

  In the demolding, the lower piece mold 6 and the upper piece mold 7 are respectively removed from the one end side opening 51 and the other end side opening 52 of the hollow mold 5. The removal is performed by the end face of the liquid composition layer after the cross-linking curing in the hollow mold 5 and the meeting portion of the liquid composition layer after the cross-linking hardening in the holes 6b and 7b on the lower piece mold 6 and the upper piece mold 7 side. This is done against the bonding strength of the (joining part). And it is made by extracting the base | substrate 4a with which the liquid composition layer after bridge | crosslinking hardening was laminated | stacked from the inside of the hollow metal mold | die 5. FIG.

  If necessary, a shaping process is performed to remove burrs and irregularities remaining on one end face and the other end face of the liquid composition layer after crosslinking and curing.

(4-2-6) Dehydration Step The liquid composition layer after crosslinking and curing laminated on the substrate 4a is dehydrated by heat treatment to form voids 4b2 (water in the water-containing material is evaporated from the layer formed by crosslinking the rubber) And a step of forming a porous elastic layer). As heat processing conditions, 100 to 250 degreeC and 1 to 5 hours are desirable.

  By this dehydration step, the liquid composition layer after cross-linking and curing laminated on the substrate 4a becomes a porous elastic layer 4b including needle fillers 4b1 and voids 4b2 by evaporation of moisture. By forming the gap 4b2 in the elastic layer 4b, an effect of reducing the thermal conductivity in the thickness direction z of the pressure roller 4 can be obtained. Also, the heat capacity can be reduced. On the other hand, for the thermal conductivity in the plane direction xy, the needle-like filler 4b1 serves as a thermal conduction path, and the thermal conductivity is maintained higher than that in the thickness direction z.

  As described above, the elastic layer 4b having a high thermal conductivity in the plane direction xy and a lower thermal conductivity in the thickness direction z than in the plane direction xy can be formed.

(4-2-7) Lamination Step of Release Layer 4c Using an adhesive, a conductive fluororesin tube as the release layer 4c is coated on the elastic layer 4b and integrated. In the case where the elastic layer 4b and the release layer 4c are adhered to each other without using an adhesive, it is not necessary to use an adhesive. The thickness of the release layer 4c is not particularly limited as long as the release layer 4c can impart sufficient release properties to the pressurizing rotating body 4, but is, for example, 5 to 50 μm.

  In particular, 5 μm or more and less than 20 μm is desirable. If the film thickness is less than 5 μm, the release layer 4c may be scraped by passing paper, and the elastic layer 4b may be exposed before the expected life, and toner may adhere to cause image defects. Further, since the fluororesin constituting the release layer 4c has a low thermal conductivity, if it is 20 μm or more, it becomes difficult to transfer heat from the fixing film 3 as a heating member to the elastic layer 4b. Therefore, the effect of suppressing the temperature rise at the non-sheet passing portion is lowered and the heat capacity is increased, so that the rise time may be delayed.

  It is not always necessary to form the release layer 4c at the end of the process. As shown in FIG. 12, a tube 4 c to be a release layer is disposed on the inner surface (molding surface) of the mold 5 in advance. Then, the base body 4a is arranged in the mold 5 as shown in FIG. In this state, the release layer 4c can also be laminated by a method of casting the liquid composition into the mold 11. Further, after forming the elastic layer 4b, the release layer 4c can be formed by a known method such as coating with a fluororesin material.

  Here, the lower piece mold 6 and the upper piece mold 7 are reused by applying a release agent to the wetted surfaces in advance and removing the cured rubber remaining on the piece mold side after demolding. To do. If a release agent is applied, it is easy to remove the cured rubber remaining on the piece-shaped side. By applying a release agent to the molding surface 53a of the hollow mold 5 in advance, it is easy to remove the mold after the rubber is cured. Further, in the casting step, the mold 11 may be in a lateral orientation or an upside down orientation. However, since there is a possibility that air may be taken in at the time of injecting the liquid composition in the horizontal orientation or the upside-down orientation, the configuration in which the injection side is arranged on the lower side is preferable.

(5) Thermal conductivity of the elastic layer 4b Since the elastic layer 4b constituting the pressure roller 4 has the following characteristics, the rise time is shortened while suppressing the temperature rise of the non-sheet passing portion. can do.

(Ratio of axial direction thermal conductivity λ1 and thickness direction thermal conductivity λ2)
The elastic layer 4b has a ratio λ1 / λ2 between the axial direction thermal conductivity λ1 and the thickness direction thermal conductivity λ2 (hereinafter, this ratio is expressed as α) of 6 to 900. That is, the needle-like filler 4b1 is formed in the elastic layer so that the thermal conductivity λ1 in the longitudinal direction of the elastic layer 4b is 6 to 900 times the thermal conductivity λ2 in the thickness direction of the elastic layer 4b. Is oriented.

  If the thermal conductivity ratio α is 6 or less, the effect of suppressing the temperature rise of the non-sheet passing portion may not be sufficiently obtained. Moreover, in order to make it 900 times or more, the amount of acicular fillers and a space | gap increase, and processing shaping | molding is difficult. The higher the thermal conductivity ratio, the more uniform the heat in the axial direction y and the more the heat escape in the thickness direction z is suppressed. Is preferred.

  The thermal conductivity ratio α can be obtained as follows. First, a cut sample 4bs (FIG. 4) of the elastic layer 4b was cut from the pressure roller 4 with a razor. Next, the width direction thermal conductivity λ1 and the thickness direction thermal conductivity λ2 were measured by the following method, each measurement was performed five times, and the ratio was calculated using an average value.

  The measurement of the axial direction thermal conductivity λ1 and the thickness direction thermal conductivity λ2 of the elastic layer 4b will be described with reference to FIG. FIG. 6 shows a sample for thermal conductivity evaluation prepared by superposing samples 4bs cut in the circumferential direction (15 mm) × width direction (15 mm) × thickness (elastic layer thickness) so that the thickness becomes about 15 mm. When measuring the axial thermal conductivity λ1, as shown in FIG. 6, the sample to be measured was fixed with a tape TA having a thickness of 0.07 mm and a width of 10 mm. Next, in order to make the measured surface flat, the measured surface and the measured surface back surface are cut with a razor.

  Then, two sets of the sample to be measured are prepared, the sensor S is sandwiched between the samples to be measured, and measurement is performed. The measurement is anisotropic thermal conductivity measurement using a hot disk method thermophysical property measuring apparatus TPA-501 (manufactured by Kyoto Electronics Industry Co., Ltd.). The thickness direction thermal conductivity λ2 was measured by changing the direction of the sample to be measured by the same method as described above.

"Example"
As the substrate 4a, an iron cored bar having a diameter of 22.8 (mm) and a rubber laminated portion having an axial length of 320 mm was used. The water-containing material is obtained by adding water to Rheosic 250H (manufactured by Toagosei Co., Ltd.). The amount of Rheological 250H was adjusted to 1 wt% with respect to the water-containing material. The release layer 4c is composed of a conductive PFA tube having a surface resistance of 10 ⁴ Ω / □, 10 ⁵ Ω / □, 10 ¹⁰ Ω / □, 10 ¹² Ω / □, 10 ¹³ Ω / □, and a thickness of 40 μm (Gunze Co., Ltd.). Used). The needle-like filler 4b1 used pitch-based carbon fibers shown below.

<Product Name: XN-100-05M (Nippon Graphite Fiber Co., Ltd.)>
Average fiber diameter D: 9 μm
Average fiber length L: 50 μm
Thermal conductivity: 900W / (m · K)
This acicular filler is hereinafter referred to as 100-05M.

<Product Name: XN-100-15M (Nippon Graphite Fiber Co., Ltd.)>
Average fiber diameter D: 9 μm
Average fiber length L: 150 μm
Thermal conductivity: 900W / (m · K)
This acicular filler is hereinafter referred to as 100-15M.

<Product Name: XN-100-01Z (Nippon Graphite Fiber Co., Ltd.)>
Average fiber diameter D: 9 μm
Average fiber length L: 1000 μm
Thermal conductivity: 900W / (m · K)
This acicular filler is hereinafter referred to as 100-01Z.

  In the present embodiment, the elastic layer 4b and the substrate 4a are bonded together, and the elastic layer 4b and the release layer 4c are bonded using the following materials. For bonding between the elastic layer 4b and the substrate 4a, liquids A and B of “DY39-051” (trade name, manufactured by Toray Dow Corning Co., Ltd.), and “SE1819CV” for bonding the elastic layer 4b and the release layer 4c. Liquid A and liquid B (trade name, manufactured by Toray Dow Corning Co., Ltd.) were used.

  In the liquid composition blending step, a universal mixing stirrer was used, and in the silicone rubber component curing step, heat treatment was performed in a hot air oven at 90 ° C. for 1 hour. In the formation process of the elastic layer 4b, the pipe-shaped cylindrical shape having the inner diameter of 30 (mm) was used. Furthermore, in the dehydration process, heat treatment was performed in a hot air oven at 200 ° C. for 4 hours.

Example 1
5% by volume of needle-like filler “100-05M” and 20% by volume of water-containing material were mixed with uncrosslinked addition-curable liquid silicone rubber. Next, a liquid composition for forming an elastic layer was poured into a pipe-shaped cylinder having a base 4a installed therein, and an elastic layer 4b was formed through the steps of crosslinking, demolding, and dehydration. Further, the release layer 4c was coated with a conductive PFA fluororesin tube having a surface resistance of 10 ¹⁰ Ω / □ having a thickness of 40 μm on the elastic layer 4b using an adhesive. Thus, the pressure roller 4 of Example 1 was obtained.

(Examples 2 to 7)
In the same manner as in Example 1, the pressure rollers 4 of Examples 2 to 7 were obtained according to the formulations shown in Table 1.

(Comparative Example 1)
In the same manner as in Example 1, an addition-curable silicone rubber having a thermal conductivity of 0.4 W / (m · K) is used for the elastic layer 4b instead of the liquid composition listed above. And the pressure roller 4 of the comparative example 1 was obtained using the electroconductive PFA fluororesin tube with a surface resistance value of 10 ¹⁰ Ω / □ having a thickness of 40 μm.

(Comparative Examples 2 and 3)
In the same manner as in Example 1, a liquid composition in which 5% by volume of acicular filler “100-05M” and 20% by volume of a hydrous material is mixed is used. Then, using a conductive PFA fluororesin tube having a surface resistance of 10 ⁴ Ω / □ having a thickness of 40 μm and a conductive PFA fluororesin tube having a surface resistance of 10 ¹³ Ω / □ having a thickness of 40 μm, 3 pressure rollers 4 were obtained.

(Comparative Example 4)
In the same manner as in Example 1, when a liquid composition in which 45% by volume of the needle-like filler “100-01Z” and 45% by volume of the water-containing material were used, it was difficult to mold and a comparison suitable for evaluation The pressure roller 4 of Example 4 could not be obtained.

(Comparative Example 5)
When a liquid composition in which 5% by volume of the needle-like filler “100-05M” and 80% by volume of a water-containing material are used in the same manner as in Example 1, molding is difficult and this is suitable for evaluation. The pressure roller 4 of Comparative Example 5 could not be obtained.

(6) Evaluation method <Non-paper passing portion temperature rise>
The film heating type fixing device A shown in FIG. 1 on which the pressure rollers 4 of Examples 1 to 7 and Comparative Examples 1 to 3 prepared by the above method are mounted is used for the non-sheet passing portion temperature rise evaluation. did. The peripheral speed of the pressure roller 4 mounted on the fixing device A was adjusted to be 234 mm / sec, and the heater temperature was set to 230 ° C. In an environment where the temperature is 15 ° C. and the humidity is 15%, the paper that has passed through the nip portion N of the fixing device A as paper P is LTR horizontal size paper having a basis weight of 75 g / m ² (the long side of the paper is the paper transport direction Q). In a state of being perpendicular to the).

  The temperature of the surface of the film 3 in the non-sheet-passing region (region where LTR horizontal size paper does not pass) when 500 sheets are continuously passed was measured using an infrared thermography FSV-7000S manufactured by Apiste Co., Ltd.

<Rise time>
For the evaluation of the rise time, the time from when the heater switch was turned on to when the surface temperature of the fixing film 3 reached 180 ° C. was measured in the above-described fixing device A in an idling state where no paper was passed.

<Peeling discharge trace>
For the evaluation of the peeling discharge trace, the film heating type fixing device A shown in FIG. 1 on which the pressure rollers 4 of Examples 1 to 7 and Comparative Examples 1 to 3 prepared by the above method were mounted was used. The peripheral speed of the pressure roller 4 was adjusted to be 234 mm / sec.

The sheet P, the basis weight and the cut sheets of A4 horizontal size of 209 g / m ² (state where the long side of the paper is positioned perpendicular to the sheet conveyance direction Q), basis weight of 220 g / m ² LTR horizontal size cut paper was used.

The test environment was a room temperature of 23 ° C. and a humidity of 15%. After the image forming apparatus and the paper were sufficiently left in a low-humidity environment, 100 sheets of A4 paper were passed continuously (the potential of the paper feeding area of the fixing film was made constant). After that, five LTR sheets were continuously fed with halftone images. The presence or absence of image defects such as streaks and gloss unevenness on the fifth image was confirmed by five people.
If no one pointed out that the image was bad, A was assigned. If one person pointed out that the image was defective, it was assigned B. If there was an indication of a two-person image failure, it was assigned C. If there was an indication of a three-person image defect, then D was assigned. In such ranking, it was determined that there was an image defect due to peeling offset, assuming that D clearly had an image defect.

<Toner adhesion>
For the toner adhesion evaluation, the above-described film heating type heating apparatus shown in FIG. 1 on which the pressure rollers 4 of Examples 1 to 7 and Comparative Examples 1 to 3 produced by the above method were mounted was used. The peripheral speed of the pressure roller 4 was adjusted to be 234 mm / sec. As the paper P, 150 k sheets of A4 horizontal size cut paper having a basis weight of 105 g / m ² was passed, and the toner adhesion state on the pressure roller surface was confirmed.

<Evaluation results>
(Non-paper passing part temperature rise suppression effect / rise time reduction effect)
Table 1 shows the evaluation results of the thermal conductivity ratio α, the non-sheet passing portion temperature, and the rise time.

  In Comparative Example 1, the non-sheet-passing portion temperature is 306 ° C. If the temperature is lower than this temperature, there is a non-sheet-passing portion temperature rise suppressing effect. Further, in Comparative Example 1, the rise time is 24.0 seconds, and if this time is shorter than 22.8 seconds, which is shortened by 5%, there is an effect of shortening the rise time.

  In Example 1, the non-sheet-passing portion temperature was 282 ° C., and the non-sheet-passing portion temperature rise suppression was confirmed. The rise time was 22.6 seconds, and the effect of shortening the rise time was also confirmed.

  Also in Examples 2 to 7, as shown in Table 1, the non-sheet-passing portion temperature rise suppressing effect and the rise time shortening effect were confirmed.

(Peeling discharge suppression effect)
In Examples 1 to 6, image defects due to the peeling discharge trace were not confirmed.

  In Example 7, the image defect due to the peeling discharge trace was slightly confirmed, but it was at a level where there was no problem in actual use.

  In Comparative Example 3, image defects due to peeling discharge traces were clearly confirmed.

(Toner adhesion suppression effect)
In Examples 1 to 7, toner adhesion was not confirmed on the pressure roller surface.

  In Comparative Example 2, a small amount of toner was confirmed on the pressure roller surface, and toner adhesion was also confirmed on the back surface of the paper.

  The pressure roller (nip portion forming member) 4 of Examples 1 to 7 described above is obtained as follows. It has the base | substrate 4a, the elastic layer 4b formed on the base | substrate 4a, and the electroconductive resin surface layer 4c formed on the elastic layer 4b. The elastic layer 4b is elastically deformed by pressure contact with the heating member 3 to form a nip portion N for nipping and conveying the sheet P carrying the toner image T and heating it.

The elastic layer 4b includes a needle-like filler 4b1, and the needle-like filler 4b1 has a thermal conductivity λ1 in the longitudinal direction y of the elastic layer 4b of 6 times or more and 900 times or less than a thermal conductivity λ2 in the thickness direction z. It is oriented in the elastic layer 4b. The surface resistance value of the resin surface layer 4c is 10 ⁵ Ω / □ or more and 10 ¹² Ω / □ or less.

  As a result, it is possible to provide a pressure roller that suppresses charging of the surface layer of the heating member 3 and can achieve both suppression of temperature rise at the non-sheet passing portion and shortening of the rise time, and an image heating apparatus including the pressure roller.

(Examples 8-14, Comparative Examples 4-8)
In the following Examples 8 to 14 and Comparative Examples 4 to 6, the thickness of the release layer 4c of the pressure roller 4 and the non-passage of the pressure roller 4 of Examples 1 to 7 and Comparative Examples 1 to 6 described above. This shows an investigation of the relationship between the suppression of temperature rise at the head and the shortening of the rise time.

As the release layer 4c, conductive PFA tube thicknesses of 10 μm, 15 μm, and 18 μm having a surface resistance value of 10 ¹⁰ Ω / □ manufactured by Gunze Co., Ltd. were used. In order to adhere the elastic layer 4b and the release layer 4c, liquid A and liquid B of “SE1819CV” (trade name, manufactured by Toray Dow Corning Co., Ltd.) were used.
Also, 350-J made by Mitsui DuPont Fluorochemical Co., Ltd. and conductive filler (conductive carbon) dispersed in water so that the surface resistance of the fired PFA coat is 10 ¹⁰ Ω / □ Was used. This was coated by spraying, dried, and then baked at 350 ° C. for 7 minutes in an electric oven to form a conductive PFA-coated surface layer having a thickness of 5 μm and 10 μm.

(Example 8)
This corresponds to the pressure roller 4 of the first embodiment. As shown in Table 2, a conductive PFA tube having a thickness of 15 μm was coated as a release layer 4c using an adhesive on the elastic layer 4b to obtain a pressure roller 4 of Example 8. Other prescriptions, configurations, and manufacturing methods of the pressure roller 4 are the same as those of the pressure roller 4 of the first embodiment.

(Examples 9, 10, 12, and 14)
These correspond to the pressure rollers 4 of Examples 2, 3, 5, and 7, respectively. The elastic layer 4b of each pressure roller 4 is coated with a PFA tube having a thickness of 15 μm, 10 μm, 15 μm, and 18 μm as a release layer 4c using an adhesive, whereby the pressure roller 4 of each example is obtained. (Table 2). Other prescriptions, configurations, and manufacturing methods of the pressure roller 4 are the same as those of the pressure roller 4 of the first embodiment.

(Example 11)
Corresponding to the pressure roller 4 of Example 4, a release layer 4c was formed on the elastic layer 4b as a coating layer as follows. That is, as the release layer 4c, a material obtained by dispersing 350-J manufactured by Mitsui DuPont Fluorochemical Co., Ltd. and a conductive filler (conductive carbon) in water was used. This was coated by spraying, dried and then baked at 350 ° C. for 7 minutes in an electric oven to form a 10 μm thick PFA coat. The other prescription, configuration, and manufacturing method of the pressure roller 4 are the same as those of the pressure roller 4 of the first embodiment (Table 2).

(Example 13)
Corresponding to the pressure roller 4 of Example 6, similarly to Example 11, a PFA coat having a thickness of 10 μm was applied as a release layer 4c on the elastic layer 4b. The other prescription, configuration, and manufacturing method of the pressure roller 4 are the same as those of the pressure roller 4 of the first embodiment (Table 2).

(Comparative Example 4)
Corresponding to the pressure roller 4 of Comparative Example 1, as a release layer 4c using an adhesive on the elastic layer 4b, as shown in Table 2, a surface resistance value of 10 ¹⁰ Ω / □ with a thickness of 25 μm. The pressure roller 4 of Comparative Example 4 was obtained by covering the conductive PFA tube. Other prescriptions, configurations, and manufacturing methods of the pressure roller 4 are the same as those of the pressure roller 4 of Comparative Example 1.

(Comparative Example 5)
Corresponding to the pressure roller 4 of Comparative Example 2, a PFA coat having a thickness of 3 μm was applied as a release layer 4c on the elastic layer 4b in the same manner as in Example 11. The other prescriptions, configurations, and manufacturing methods of the pressure roller 4 are the same as those of the pressure roller 4 of Comparative Example 2 (Table 2).

(Comparative Example 6)
Corresponding to the pressure roller 4 of Comparative Example 3, a conductive PFA tube having a surface resistance of 10 ¹⁰ Ω / □ having a thickness of 20 μm is coated on the elastic layer 4b as a release layer 4c using an adhesive. Thus, the pressure roller 4 of Comparative Example 6 was obtained. Other prescriptions, configurations, and manufacturing methods of the pressure roller 4 are the same as those of the pressure roller 4 of Comparative Example 3.

(Comparative Example 7)
Corresponding to the pressure roller 4 of Comparative Example 4, as in Comparative Example 4, when using a liquid composition in which 45% by volume of needle-like filler “100-01Z” and 45% by volume of water-containing material are used. It was difficult to form and a pressure roller suitable for evaluation could not be obtained.

(Comparative Example 8)
Corresponds to the pressure roller 4 of Comparative Example 5, and in the same manner as in Comparative Example 5, 5% by volume of needle-like filler “100-05M” and 80% by volume of water-containing material are mixed in the same manner as in Example 1. When the liquid composition is used, it is difficult to mold. Therefore, a pressure roller suitable for evaluation could not be obtained.

(7) Evaluation method <Non-sheet passing portion temperature rise> and <rise time> are the same as described in the above section (6).

<Toner adhesion>
For the toner adhesion evaluation, the film heating type fixing device A shown in FIG. 1 on which the pressure rollers of Examples 8 to 14 and Comparative Examples 4 to 6 produced by the above method were mounted was used. The peripheral speed of the pressure roller 4 was adjusted to be 234 mm / sec. As the paper P, 150 k sheets of A4 horizontal size cut paper having a basis weight of 105 g / m ² was passed, and the toner adhesion state on the pressure roller surface was confirmed.

<Evaluation results>
Table 1 shows the evaluation results of the thermal conductivity ratio α, the non-sheet passing portion temperature, and the rise time.

  In Comparative Example 4, the non-sheet-passing portion temperature is 305 ° C. If the temperature is lower than this temperature, there is a non-sheet-passing portion temperature rise suppressing effect. In Comparative Example 4, the rise time is 23.7 seconds, and if this time is shorter than 21.9 seconds, which is 8% shorter, there is an effect of shortening the rise time.

  In Example 8, the non-sheet-passing portion temperature was 280 ° C., and the non-sheet-passing portion temperature rise suppression was confirmed. The rise time was 21.6 seconds, and the effect of shortening the rise time was also confirmed.

  Also in Examples 9 to 14, as shown in Table 2, the non-sheet-passing portion temperature rise suppressing effect and the rise time shortening effect were confirmed.

  In Comparative Example 6, the non-sheet-passing portion temperature was 279 ° C. and the non-sheet-passing portion temperature rise suppression was confirmed, but the rise time was 22.1 seconds, and the target 8% reduction could not be achieved.

  In Examples 8 to 14, toner adhesion was not confirmed on the pressure roller surface.

  In Comparative Example 5, toner adhered to the pressure roller surface. It was confirmed that the PFA coat on the pressure roller surface layer, which hits both ends of the paper when the paper was passed, disappeared.

  The pressure roller (nip portion forming member) 4 of Examples 8 to 14 described above is obtained as follows. It has the base | substrate 4a, the elastic layer 4b formed on the base | substrate 4a, and the electroconductive resin surface layer 4c formed on the elastic layer 4b. The elastic layer 4b is elastically deformed by pressure contact with the heating member 3 to form a nip portion N for nipping and conveying the sheet P carrying the toner image T and heating it.

  The elastic layer 4b includes an acicular filler 4b1, and in the acicular filler 4b1, the thermal conductivity λ1 in the longitudinal direction y of the elastic layer 4b is 6 times or more and 900 times or less than the thermal conductivity λ2 in the thickness direction z. Thus, the elastic layer 4b is oriented in the layer. The thickness of the resin surface layer 4c is not less than 5 μm and less than 20 μm.

  As a result, it is possible to provide a pressure roller capable of achieving both suppression of temperature rise in the non-sheet passing portion and shortening of the rise time, and an image heating apparatus including the pressure roller.

(Other matters)
(1) In each of the above-described embodiments, the example in which the pressure roller 4 that is a rotating body is used as the nip portion forming member has been described, but the present invention is not limited thereto. For example, the nip portion forming member 4 may be in the form of an endless pressure belt that is a rotating body. More specifically, the substrate 4a has an endless shape (belt shape) made of a thin heat-resistant resin such as polyimide, polyamideimide, polyetheretherketone (PEEK), or a thin metal such as stainless steel (SUS) or nickel (Ni). These members are used. In this embodiment, the elastic layer 4b having the above-described structure is provided on the substrate.

  The nip portion forming member 4 as a rotating body is driven to rotate or is rotated by the rotation of the heating member 3 to sandwich and convey the recording material at the nip portion N.

  (2) The nip portion forming member 4 is not limited to the form of the above rotating body. It can also be in the form of a non-rotating member such as a horizontally long pad-like member as shown in FIG. 13 having a friction coefficient on the surface smaller than that of the heating member 3 and the recording material P that are rotationally driven.

  The recording material P introduced into the nip N slides on the back surface side (non-image forming surface side) of the heating member 3 while sliding with respect to the surface having a small friction coefficient of the nip portion forming member 4 in the form of a non-rotating member. The nip portion N is nipped and conveyed by the rotational conveyance force.

  (3) The heating member 3 may be a heat roller. The heating method of the heating member 3 is not limited to the ceramic heater, and may be a heat ray irradiation method using a halogen run or the like, an electromagnetic induction heating method, a heat ray irradiation method, or the like. It is not limited to the internal heating method, and an external heating method may be used.

  (4) The toner image forming principle and image forming process on the recording material P are not limited to the transfer type electrophotographic process. A direct electrophotographic process using photosensitive paper as a recording material may be used. A transfer system using a dielectric material or a direct electrostatic recording process using an image bearing member, an intermediate transfer system using a magnetic material, or a direct magnetic recording process may be used.

  (5) In addition to the fixing device that fixes the unfixed toner image of the embodiment as a fixed image, the image heating device reheats and pressurizes the toner image assumed to be applied to the recording material or the toner image once heated and fixed. An image quality reforming device that improves the degree and the like is also included.

  A ... Image heating device 3. Heating member 4. Nip forming member 4a ... Substrate 4b ... Elastic layer 4b1 ... Needle-like filler 4c ... Resin surface layer, N ... Nip part , P ... Recording material, T ... toner image

Claims (14)

A toner image is carried by having a base, an elastic layer formed on the base, and a conductive resin surface layer formed on the elastic layer, and the elastic layer is elastically deformed by pressure contact with a heating member. A nip part forming member for forming a nip part for nipping and conveying a sheet-like recording material and heating it,
The elastic layer includes a needle-like filler, and the needle-like filler has the elastic layer such that the thermal conductivity in the longitudinal direction of the elastic layer is 6 to 900 times the thermal conductivity in the thickness direction. A nip portion forming member, wherein the resin surface layer has a surface resistance value of 10 ⁵ Ω / □ or more and 10 ¹² Ω / □ or less. A toner image is carried by having a base, an elastic layer formed on the base, and a conductive resin surface layer formed on the elastic layer, and the elastic layer is elastically deformed by pressure contact with a heating member. A nip part forming member for forming a nip part for nipping and conveying a sheet-like recording material and heating it,
The elastic layer includes a needle-like filler, and the needle-like filler has the elastic layer such that the thermal conductivity in the longitudinal direction of the elastic layer is 6 to 900 times the thermal conductivity in the thickness direction. A nip portion forming member, wherein the resin surface layer is oriented in a thickness of 5 μm or more and less than 20 μm.   The nip portion forming member according to claim 1, wherein the elastic layer is a porous elastic layer.   The nip portion forming member according to claim 3, wherein the elastic layer has a porosity of 20 volume% or more and 70 volume% or less. The nip portion forming member according to any one of claims 1 to 4, wherein the elastic layer contains 5% by volume to 40% by volume of the acicular filler.
Rotating body for pressurization.   The nip portion forming member according to any one of claims 1 to 5, wherein the elastic layer includes a mixture of addition-curable silicone rubber.   The nip portion forming member according to any one of claims 1 to 6, wherein the needle-like filler is carbon fiber.   The nip portion forming member according to claim 1, wherein the resin surface layer contains at least conductive carbon.   The nip portion forming member according to any one of claims 1 to 8, wherein the resin surface layer is a PFA tube.   The nip portion forming member according to any one of claims 1 to 8, wherein the resin surface layer is a PFA coat.   The nip portion forming member according to any one of claims 1 to 10, wherein the nip portion forming member is a rotating body that is rotationally driven or is rotated by the rotation of the heating member.   11. The nip portion according to claim 1, wherein the nip portion forming member is a non-rotating member having a smaller surface friction coefficient than the heating member and the recording material that are rotationally driven. Forming member.   An image heating apparatus comprising: a heating member; and a nip portion forming member that forms a nip portion that sandwiches and conveys and heats a recording material carrying a toner image that is elastically deformed by pressure contact with the heating member, The image heating apparatus, wherein the nip portion forming member is the nip portion forming member according to any one of claims 1 to 12. It is a manufacturing method of the nip part formation member according to any one of claims 1 to 12,
(1) A liquid composition for forming an elastic layer containing uncrosslinked rubber, acicular filler dispersed in the rubber, and a water-containing material is flowed in a direction along the length of the substrate to form a layer of the liquid composition Forming on the substrate;
(2) a step of crosslinking the rubber in the layer of the liquid composition while retaining moisture in the water-containing material;
(3) a step of evaporating water in the water-containing material from a layer formed by crosslinking the rubber to form a porous elastic layer;
The manufacturing method of the nip part formation member characterized by having.