JP2005249850A - Thermally conductive elastic member, heat fixing member, and heat fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat conductive elastic member having sufficient heat conductivity when used as an elastic layer of a heat fixing member of an electrophotographic image forming apparatus and having an appropriate range when hardness is used as an elastic layer. And providing a heat fixing member having the heat conductive elastic member as an elastic layer.
A matrix phase composed of a resin containing a heat conductive filler and a dispersed phase composed of a material having a lower hardness than the matrix layer dispersed in the matrix phase, the matrix phase thermal conductivity λa and the dispersed phase heat. The above problem is achieved by the heat conductive elastic member whose relationship with the conductivity λb is λa ≧ 2λb and the overall heat conductivity λ is in the range of 0.5 to 3.0 W · (m · K) ^−1. Is done.
[Selection] Figure 1

Description

  The present invention relates to a heat conductive elastic member, particularly a heat conductive elastic member useful as an elastic layer for a heat fixing member incorporated in a toner image fixing device for electrophotography, and further, the heat conductive elastic member is used as an elastic layer. And a heat fixing apparatus incorporating the heat fixing member.

  In general, in a heat fixing apparatus used in an electrophotographic system, a pair of heated rollers and rollers, a film and rollers, and a belt and rollers are pressed against each other, and a recording material holding an unfixed toner image is provided. Then, it is introduced into a pressure contact portion formed between the rotating bodies, heated and melted, and then cooled and solidified to form a permanent image on the recording material.

  A rotating body that contacts an unfixed toner image held on a recording material is called a fixing member, and is called a fixing roller, a fixing film, a fixing belt, or the like depending on the form.

  Many of these fixing members are formed by laminating a heat-resistant elastic resin layer in a single layer or multiple layers on a substrate formed of a metal or a heat-resistant resin (for example, Patent Documents 1 and 2). reference).

  In addition, heat-resistant rubber materials such as silicone rubber and fluorine rubber are often used for the heat-resistant elastic layer formed on the base material. However, these heat-resistant rubber materials have low thermal conductivity and are not easily heated. When the heat is transferred to the recording material, it becomes a heat resistance layer. Therefore, a method for improving the thermal conductivity of the elastic layer by blending these heat-resistant rubber materials with an inorganic filler having high thermal conductivity is known (for example, see Patent Document 3).

  As a technique for improving the thermal conductivity in the elastic layer of the heat fixing member, a material in which the elastic layer is made by foaming silicone rubber is used, and by encapsulating a liquid or jelly-like high thermal conductivity substance in the foam layer, There has been proposed a method for securing a heat flow path and increasing the thermal response to a temperature drop (for example, see Patent Document 4).

  By the way, a fixing device incorporating a fixing member having such an elastic layer is widely used particularly when fixing unfixed toner in which a plurality of toners of different colors such as color images are overlapped (so-called color). Copier, color printer). This has the effect of preventing image displacement and blurring by improving the color mixing property by wrapping the toner image by deformation of the elastic layer.

However, in order to reduce the heat resistance of the heat-resistant rubber material used as the elastic member, increasing the blending amount of the heat-conductive filler increases the hardness, so the deformation of the elastic layer is suppressed and unfixed. It is difficult to sufficiently envelop the toner image, and as a result, it is difficult to obtain sufficient color mixing properties, resulting in problems such as deterioration in color reproducibility and collapse of the toner image.
JP-A-10-111613 JP 2001-27862 A JP 2000-187407 A JP-A-4-166970

  That is, the present invention provides a thermally conductive elastic member having sufficient thermal conductivity when used as an elastic layer of a fixing member and having an appropriate range when the hardness is an elastic layer, and the thermal conductivity It is an object of the present invention to provide a heat fixing member having an elastic layer as an elastic layer.

  In addition, the present invention provides a color image obtained with sufficient color mixing and improved image quality when used as a heat fixing device of an electrophotographic image forming apparatus. It is an object of the present invention to provide a heat fixing device that can reduce the set temperature of the heater and achieve energy saving.

  In order to solve the above problems, the present inventors have intensively studied, blended a heat-resistant rubber material containing a heat-conductive filler into a fine powder of a heat-resistant rubber having a low hardness, and heat-cured when heat-cured. The present inventors have found that the property can be sufficiently secured and the flexibility can be improved, and have further studied and finally reached the present invention.

  That is, the present invention is a heat conductive elastic member, a heat fixing member, and a heat fixing device having the following configuration.

[1] A matrix phase made of a resin containing a heat conductive filler and a dispersed phase made of a material having a hardness lower than that of the matrix layer dispersed in the matrix phase. The matrix phase thermal conductivity λa and the dispersed phase heat conduction A thermal conductive elastic member characterized in that the relationship with the rate λb is λa ≧ 2λb and the overall thermal conductivity λ is in the range of 0.5 to 3.0 W · (m · K) ⁻¹ .

[2] The heat conductive elastic member described above, wherein the heat conductive filler is made of an inorganic substance.

[3] The heat conductive elastic member described above, wherein the heat conductive filler has a heat conductivity λf ≧ 10 W · (m · K) ⁻¹ .

[4] The heat conductive elastic member described above, wherein the heat conductive filler has a thermal conductivity λf ≧ 100 W · (m · K) ⁻¹ .

[5] The recording material on which the unfixed image is formed is passed through a fixing nip formed by press-contacting a heat fixing member having a heating unit and a pressure member, so that the unfixed image is made permanent on the recording material. A heat fixing member incorporated in a heat fixing device for fixing as an image, wherein the heat fixing member has an elastic layer made of any one of the above heat conductive elastic members.

[6] The heat fixing member as described above, wherein a dispersed phase in the heat conductive elastic member is formed of an elastic material.

[7] The heat fixing member as described above, wherein the elastic material is silicone rubber powder.

[8] The heat fixing member as described above, wherein the matrix phase in the heat conductive elastic member is formed by curing a silicone rubber composition containing a heat conductive filler.

[9] A heat fixing apparatus comprising any of the heat fixing members described above.

  Since the heat conductive elastic member of the present invention has a relatively low hardness while having sufficient heat conductivity, the elasticity of the heat fixing member of the heat fixing device of the electrophotographic image forming apparatus, particularly the electrophotographic color image forming apparatus. Useful as a layer. That is, in the electrophotographic image forming apparatus in which the heat-fixing part agent having the heat conductive elastic member of the present invention as an elastic layer is incorporated, the color image has a sufficient color mixing property, and the image quality is improved. Since the set temperature of the heater in the heat fixing device can be lowered, energy saving is also achieved.

  In FIG. 1, the typical sectional drawing of the heat conductive elastic member of this invention is shown.

  In the figure, 1 is a heat conductive elastic member of the present invention, and the heat conductive elastic member has a relatively low hardness in a relatively high heat conductive matrix phase 1 containing a high heat conductive filler. A dispersed phase 2 such as silicone powder is dispersed.

  The matrix phase 1 is constituted by curing an elastic body such as a rubber composition containing a heat conductive filler. As the rubber component, silicone rubber, fluorine rubber or the like is used because of heat resistance.

In addition, the thermally conductive filler contained in the rubber component, that is, contained in the matrix phase 1 is preferably an inorganic substance, particularly a metal, a metal compound, or the like because of its relatively high thermal conductivity. (SiC), silicon nitride (Si ₃ N ₄ ), boron nitride (BN), aluminum nitride (AlN), alumina (Al ₂ O ₃ ), zinc oxide (ZnO), magnesium oxide (MgO), copper (Cu), Examples thereof include high thermal conductive fine powders such as aluminum (Al), silver (Ag), iron (Fe), nickel (Ni), etc., and these can be used alone or in admixture of two or more. The particle size is preferably about 0.01 to 100 μm from the viewpoint of improving the dispersibility in the matrix phase and the thermal conductivity. Furthermore, in order to improve the thermal conductivity of the matrix phase 1, the thermal conductivity λf of the thermal conductive filler used here is 10 W · (m · K) ⁻¹ or more, preferably 100 W · (m · K). ^{A value of -1} or more is desirable. When a filler having a λf of less than 10 W · (m · K) ⁻¹ is used as a filler, a large amount is required to achieve the necessary thermal conductivity λ when used as a thermally conductive elastic member. It tends to be difficult to obtain an effect.

  The component of the dispersed phase 2 dispersed in the matrix phase 1 may be any fine particle having low hardness and dispersed in the matrix phase raw material. A heat-resistant rubber powder obtained by adding various additives and fillers as necessary to the rubber component used in the phase and curing it in a fine powder form is preferable. Specific examples include silicone rubber powder and fluororubber powder.

In the present invention, it is essential that the thermal conductivity λa of the matrix phase 1 is at least twice the thermal conductivity λb of the dispersed phase 2, that is, λa ≧ 2λb, and the heat conductive elastic member the thermal conductivity of λ is in 0.5~3.0W · (m · K) ^-1 is needed to use as the elastic layer of the heat fixing member of the electrophotographic image forming apparatus. By satisfying λa ≧ 2λb, sufficient thermal conductivity can be achieved for the thermally conductive elastic member, regardless of whether the dispersed phase 2 having low thermal conductivity is dispersed in the matrix phase 1. From the viewpoint of ensuring flexibility as a heat fixing member, the value of λa is preferably 20 W · (m · K) ⁻¹ or less. Further, when the thermal conductivity λ of the thermal conductive elastic member is outside the above range, the thermal conductivity becomes insufficient or the thermal conductivity becomes excessive, and the toner image cannot be fixed well.

  The thermal conductivity of the matrix phase 1 is obtained by curing a raw material composition that does not contain the component forming the dispersed phase 2 to prepare a sample piece having a diameter of 30 mm and a thickness of 13 mm. It is measured under room temperature conditions using an apparatus TPA-501 (sensor: RTK-φ7). Moreover, about the heat conductivity of a heat conductive elastic member, the sample piece was created similarly to the above and the raw material composition which disperse | distributed two components of the dispersed phase was measured similarly.

  In addition, this heat conductive elastic member is manufactured by mix | blending and heat-resistant silicone rubber powder to the silicone rubber liquid raw material composition containing a heat conductive filler, for example. In addition, it can also carry out on a base material in the case of this hardening.

  Further, unless otherwise specified, the hardness of the heat conductive elastic member is a value measured by using a type A durometer (JIS-A type) by preparing a sample piece having a diameter of 30 mm and a thickness of 13 mm. Furthermore, the difference in hardness between the matrix phase 1 and the dispersed phase 2 is that the indentation depth of 500 nm in the sample cross section is obtained by using Toyo Technica Co., Ltd./Thin Film Mechanical Property Evaluation System Nano Indenter XP / DCM-Dynamic Contact Module etc. It can obtain | require by measuring the hardness of each phase at the time.

  A heat fixing member having the heat conductive elastic member of the present invention as an elastic layer will be described.

  FIG. 2 is a schematic cross-sectional view of the layer structure of an example of the heat fixing member.

  In the figure, reference numeral 3 denotes a substrate of the heat fixing member, and the shape, structure, size and the like thereof are not particularly limited and are appropriately selected according to the purpose. Of these, a roll or belt is preferred from the standpoints of operating efficiency, occupied volume, and the like. These materials are not particularly limited as long as they have excellent heat resistance, mechanical strength, and good thermal conductivity. For example, in the case of a roll, a metal such as aluminum, iron, copper, nickel, etc. SUS, alloys such as brass, ceramics and the like. Examples of the base material suitable for the belt-shaped member include, in addition to the above materials, resins such as polyethylene terephthalate, polybutylene naphthalate, polyester, thermosetting polyimide, thermoplastic polyimide, polyamide, polyamideimide, polyacetal, and polyphenylene sulfide. Materials. The resin is preferably added with conductive powder to control the volume resistivity, and among them, a polyimide film in which the volume resistivity is controlled by adding and dispersing carbon black is preferable. In particular, regarding these belt-like substrates, an endless belt is more preferable because if there is a seam, the applied pressure changes at that portion and affects the image quality.

  Reference numeral 4 denotes an elastic layer, which is formed of the above-described heat conductive elastic member with an arbitrary thickness and shape according to specifications.

  The method for forming the elastic layer 4 is not particularly limited, and is generally formed on the substrate using a molding method such as mold molding or coat molding.

  Reference numeral 5 denotes a release layer, which is often formed of silicone rubber, fluororubber, fluororesin, etc., but silicone rubber or fluororesin is particularly preferable from the viewpoint of releasability. The formation method and thickness are not particularly limited, but generally, a method of coating a release layer material formed in a tube shape, coating the outer surface of the elastic layer 4 with fine particles of the material, and heat melting And the method of forming is known, and the thickness is generally 5 to 100 μm.

  Furthermore, a primer layer or an adhesive layer may be formed between the layers for the purpose of adhesion, energization, or the like. Each layer may have a multilayer structure within the scope of the present invention. Further, layers other than those shown here may be formed on the inner and outer surfaces of the heat fixing member for the purpose of slidability, heat absorption, releasability and the like. The order in which these layers are formed is not particularly limited, and may be appropriately changed depending on the convenience of each process. If necessary, a layer of polyimide, polyimide amide, fluororesin, or the like may be provided on the inner surface of the substrate in order to improve slidability.

  Next, an example of a heat fixing apparatus incorporating the heat fixing member of the present invention will be described.

  FIG. 3 is a schematic view showing an example of a belt heating type heat fixing apparatus using a ceramic heater as a heating body.

  In the figure, reference numeral 11 denotes a cylindrical or endless heat fixing member, which is as described above. There is a heat-resistant and heat-insulating belt guide 12 for holding the heat-fixing member 11, and the heat-fixing member 11 is heated to a position in contact with the heat-fixing member 11 (substantially at the center of the lower surface of the belt guide 12). A ramic heater 13 is fitted and fixedly supported in a groove formed and provided along the guide length. The heat fixing member 11 is loosely fitted on the belt guide 12. The pressurizing rigid stay 14 is inserted inside the belt guide 12.

  On the other hand, a pressure roller 15 that opposes the heat fixing member 11 is provided. In this example, the pressure roller is an elastic pressure roller, that is, the core metal 15a is provided with an elastic layer 15b of silicone rubber to reduce the hardness, and both ends of the core metal 15a are disposed in front of the apparatus (not shown). Between the side and back chassis side plates, the bearings are rotatably supported. The elastic pressure roller is covered with a PFA (tetrafluoroethylene / perfluoroalkyl ether copolymer) tube in order to improve surface properties.

  By pressing the pressure springs (not shown) between both ends of the pressure rigid stays 14 and the spring receiving members (not shown) on the apparatus chassis side, a pressing force is applied to the pressure component stays 14. ing. As a result, the lower surface of the ceramic heater 13 disposed on the lower surface of the belt guide member 12 made of heat-resistant resin and the upper surface of the pressure roller 15 are pressed against each other with the heat fixing member 11 interposed therebetween to form the fixing nip portion 16.

  The pressure roller 15 is driven to rotate counterclockwise as indicated by an arrow by a driving means (not shown). A rotational force acts on the heat fixing member 11 by the frictional force between the pressure roller 15 and the outer surface of the heat fixing member 11 due to the rotation of the pressure roller 15, and the inner surface of the heat fixing member 11 is the fixing nip portion 16. , While rotating in close contact with the lower surface of the ceramic heater 13 in the clockwise direction as indicated by an arrow, it rotates outwardly of the belt guide 12 at a peripheral speed substantially corresponding to the rotational peripheral speed of the pressure roller 15 (pressure roller). Drive system).

  The temperature detecting elements 17 and 18 are provided as necessary, and are fixed in contact with the inner surface and the outer surface of the heat fixing member 11 by means (not shown), respectively. Measure temperature while sliding.

  Based on the print start signal, rotation of the pressure roller 15 is started, and heat-up of the ceramic heater 16 is started. At the moment when the rotational peripheral speed of the heat fixing member 11 is stabilized by the rotation of the pressure roller 15 and the temperature of the temperature detecting element 18 provided on the outer surface of the heat fixing member 11 rises to a predetermined temperature, for example, 180 ° C., the fixing nip portion. A recording material 20 carrying a full color toner image 19 as a material to be heated is introduced between the 16 heat fixing members 11 and the pressure roller 15 with the toner image carrying surface side facing the heat fixing member 11. The recording material 20 is in close contact with the lower surface of the ceramic heater 13 via the heat fixing member 11 in the fixing nip portion 16, and moves and passes through the fixing nip portion 16 together with the heat fixing member 11. In the moving and passing process, the heat of the heat fixing member 11 is applied to the recording material 20 and the toner image 19 is heated and fixed on the surface of the recording material 20. The recording material 20 that has passed through the fixing nip portion 16 is conveyed separately from the outer surface of the heat fixing member 11.

  The ceramic heater 13 as a heating body is a horizontally long linear heating body having a low heat capacity and having a longitudinal direction as a direction orthogonal to the moving direction of the heat fixing member 11 and the recording material 20. A heater substrate 13a made of aluminum nitride or the like, and a heating layer 13b provided on the surface of the heater substrate 13a along the length thereof, for example, an electric resistance material such as Ag / Pd (silver / palladium) is about 10 μm, width 1 It is preferable to use a heat generating layer 13b provided by coating by screen printing or the like to about 5 mm and a protective layer 13c such as glass or fluororesin provided thereon as a basic structure. The ceramic heater to be used is not limited to this.

  And when it supplies with electricity between the both ends of the heat_generation | fever layer 13b of the ceramic heater 13, the heat_generation | fever layer 13b heat | fever-generates and the heater 13 heats up rapidly.

  The ceramic heater 13 is fixedly supported by fitting the protective layer 13c upward in a groove formed along the longitudinal direction of the guide at the substantially central portion of the lower surface of the belt guide 12. The surface of the sliding member 13 d of the ceramic heater 13 and the inner surface of the heat fixing member 11 slide in contact with each other at the fixing nip portion 16 that comes into contact with the heat fixing member 11.

  In this example, an endless belt-like member is shown as the heat fixing member. However, a roller-like heat fixing member using a hollow substrate may be used, and the pressure member may be an endless belt member. Also good.

  Hereinafter, the present invention will be described by way of examples.

(Example 1)
Addition-type silicone rubber (viscosity: 13 Pa · s (using a BH type rotational viscometer, No. 5 × 10 rpm, room temperature)) with a rubber hardness after curing (measured by the method specified in JIS K7312, SRIS) of 7 ° 50 parts by volume and 30 parts by volume of aluminum nitride (AlN) powder (trade name: aluminum nitride powder shapepal H grade, manufactured by Tokuyama Co., Ltd.) are uniformly mixed to form a silicone rubber composition (1-a) serving as a matrix phase. Obtained. The thermal conductivity (heat conductivity λa as a matrix phase) of the cured sample piece of this silicone rubber composition (1-a) was 1.3 W (m · K) ⁻¹ .

After uniformly dispersing 20 parts by volume of silicone rubber powder (trade name: KMP-598, manufactured by Shin-Etsu Chemical Co., Ltd.) in 80 parts by volume of the silicone rubber composition (1-a), conditions of 200 ° C. for 4 hours Curing was performed to obtain a heat conductive elastic member (1-b). The hardness of the obtained heat conductive elastic member (1-b) was 14 °, and the heat conductivity λ was 1.1 W (m · K) ⁻¹ . The thermal conductivity λb of the silicone rubber powder as the dispersed phase is the value (0.20 W (m · K) ⁻¹ ) of the silicone rubber indicated in the heat transfer engineering data (4th revised edition, Maruzen Co., Ltd.). ). The thermal conductivity λf of the thermally conductive filler is described in the document “Technology for Measuring and Evaluating Thermal Conductivity and Thermal Conductivity of Heat Dissipating Materials for Electronic Equipment / Parts” (published in February 2003). Use the value that was written. The results are shown in Table 1.

  On the other hand, a heat conductive elastic member (1-b) having a silicone rubber powder as a dispersed phase on a nickel base (thickness 50 μm, diameter 34 mm) having a polyimide sliding layer 5 μm thick on the inner surface. It was cured and formed under the conditions of 200 ° C. and 4 hours so that the elastic layer had a thickness of 300 μm. Further, a fluororesin (PFA (tetrafluoroethylene / perfluoroalkyl ether copolymer)) tube (thickness 30 μm) is coated thereon, and both ends are cut to a predetermined length, whereby a heat fixing member (1 -C) was obtained.

(Example 2)
In Example 1, the silicone rubber composition (2-a) which becomes a matrix phase was obtained by using the silicone rubber stock solution and the aluminum nitride (AlN) powder in an amount of 40 parts by volume and 40 parts by volume, respectively. The cured sample piece had a thermal conductivity λa of 2.5 W (m · K) ⁻¹ . Thereafter, a heat conductive elastic member (2-b) was obtained in the same manner as in Example 1. The heat conductive elastic member (2-b) had a hardness of 25 ° and a heat conductivity λ of 2.1 W (m · K) ⁻¹ . The results are shown in Table 1.

  Further, a heat fixing member (2-c) was obtained in the same manner as in Example 1 except that this heat conductive elastic member (2-b) was used as an elastic layer.

(Example 3)
In Example 1, silicon carbide (SiC) powder (trade name: silicon carbide powder GC-15R, manufactured by Yakushima Electric Works Co., Ltd.) was used instead of aluminum nitride, and silicone rubber powder (trade name: X) was used as the silicone rubber powder. The silicone rubber composition (3-a), the heat conductive elastic member (3-b) and the heat fixing member (3) are the same as in Example 1 except that -52-875 manufactured by Shin-Etsu Chemical Co., Ltd. is used. -C) was obtained. In addition, the thermal conductivity λa of the cured product of the silicone rubber composition (3-a) is 1.4 W (m · K) ⁻¹ , and the hardness of the heat conductive elastic member (3-b) is 8 °. The thermal conductivity λ was 1.2 W (m · K) ⁻¹ . The results are shown in Table 1.

Example 4
In Example 1, a silicone rubber composition (4-a) was used in the same manner as in Example 1 except that zinc oxide (ZnO) powder (zinc oxide first type, manufactured by Sakai Chemical Industry Co., Ltd.) was used instead of aluminum nitride. ), A heat conductive elastic member (4-b) and a heat fixing member (4-c). In addition, the thermal conductivity λa of the cured product of the silicone rubber composition (4-a) is 0.80 W (m · K) ⁻¹ , and the hardness of the heat conductive elastic member (4-b) is 18 °. The thermal conductivity λ was 0.68 W (m · K) ⁻¹ . The results are shown in Table 1.

(Example 5)
Example 3 is the same as Example 3 except that alumina (Al ₂ O ₃ ) powder (trade name: fine low-soda alumina AL-45-1, Showa Denko KK) is used instead of silicon carbide (SiC) powder. Similarly, a silicone rubber composition (5-a), a heat conductive elastic member (5-b), and a heat fixing member (5-c) were obtained. The cured rubber of the silicone rubber composition (5-a) has a thermal conductivity λa of 0.71 W (m · K) ⁻¹ , and the heat conductive elastic member (5-b) has a hardness of 4 °. The thermal conductivity λ was 0.56 W (m · K) ⁻¹ . The results are shown in Table 1.

(Example 6)
In Example 1, a silicone rubber composition (6-a) serving as a matrix phase was prepared by using the silicone rubber stock solution and the aluminum nitride (AlN) powder in amounts of 30 parts by volume and 40 parts by volume, respectively. As in Example 1, except that the cured silicone rubber composition (4-a) used in Example 4 was pulverized into powder by a pulverizer and 30 parts by volume was used. An elastic member (6-b) and a heat fixing member (6-c) were obtained. The cured rubber of the silicone rubber composition (6-a) has a thermal conductivity λa of 1.6 W (m · K) ⁻¹ , and the heat conductive elastic member (6-b) has a hardness of 28 °. The thermal conductivity λ was 1.40 W (m · K) ⁻¹ . The results are shown in Table 1.

(Comparative Example 1)
In Example 1, a silicone rubber composition (7) was used in the same manner as in Example 1 except that silica (SiO ₂ ) powder (trade name: Nipsil E-200A, manufactured by Tosoh Silica Co., Ltd.) was used instead of aluminum nitride. -A), a heat conductive elastic member (7-b) and a heat fixing member (7-c) were obtained. The thermal conductivity λa of the cured product of the silicone rubber composition (7-a) is 0.3 W (m · K) ⁻¹ , the hardness of the thermal conductive elastic member (7-b) is 10 °, and the same thermal conductivity. The rate λ was 0.24 W (m · K) ⁻¹ . The results are shown in Table 1.

(Comparative Example 2)
In Example 1, the silicone rubber composition (8-) was prepared in the same manner as in Example 1 except that the usage amounts of the silicone rubber stock solution, aluminum nitride, and silicone rubber powder were 40 parts by volume, 50 parts by volume, and 10 parts by volume, respectively. a), a heat conductive elastic member (8-b) and a heat fixing member (8-c) were obtained. In addition, the thermal conductivity λa of the cured product of the silicone rubber composition (8-a) is 3.4 W (m · K) ⁻¹ , and the hardness of the heat conductive elastic member (8-b) is 46 °. The thermal conductivity λ was 3.2 W (m · K) ⁻¹ . The results are shown in Table 1.

(Comparative Example 3)
30 parts by volume of the same alumina (Al ₂ O ₃ ) powder as in Example 5 was mixed with 70 parts by volume of the same silicone rubber stock solution as in Example 1 to obtain a silicone rubber composition (9-a). Obtained. Using this silicone rubber composition (9-a) as an elastic layer, a heat fixing member (9-c) was obtained in the same manner as in Example 1 below. The thermal conductivity λa of the cured product of the silicone rubber composition (9-a) was 0.46 W (m · K) ⁻¹ . The results are shown in Table 1.

(Comparative Example 4)
Using the silicone rubber composition (1-a) of Example 1 as an elastic layer as it is, a heat fixing member (10-c) was obtained in the same manner as in Example 1 below.

≪Performance evaluation of heat fixing member≫
As the heat fixing member 11 of the heat fixing device shown in FIG. 3, the heat fixing members (1-c) to (9-c) obtained in the examples and comparative examples were used to evaluate the performance of the heat fixing member.

  As the pressure roller 15, a roller having an outer diameter of 20 mm, in which a PFA tube (thickness: 30 μm) is coated on a silicone rubber layer having a thickness of 3.0 mm, was used. Further, as the ceramic heater 13, an electric resistance material Ag / Pd was provided on the substrate made of aluminum nitride along the length by screen printing to a thickness of 10 μm and a width of 2 mm, and a glass protective layer was further provided thereon. . The driving method of the heat fixing member 11 is a pressure roller driving method. Further, the nip portion 16 formed between the pressure roller 15 and the heat fixing member 11 is set to 6.5 mm.

  After the pressure roller 15 starts rotating at a speed of 50 mm / sec, the ceramic heater 13 is energized, and when the temperature indicated by the temperature detecting element 18 reaches 180 ° C., cyan and magenta unfixed toner 19 is transferred. The recording material 20 formed in a two-color overlapping state in a 5 mm square shape was passed through the nip portion 16 to fix the toner image.

The obtained fixed image was observed with an optical microscope, and the color mixing property was evaluated according to the following criteria. In addition, the evaluation more than (circle) is set as a pass.
A: The colors are sufficiently mixed.
○: Almost mixed color.
Δ: Some color mixing.
X: Almost no color mixing.

  On the other hand, when the temperature detection element 18 on the outer surface reaches 180 ° C., the temperature of the temperature detection element 17 on the inner surface is measured, and the heat transfer performance of the heat conductive member is evaluated depending on how much the temperature is higher than the outer surface temperature. . Note that the temperature difference becomes smaller as the heat-fixing member has better heat transfer performance, and the heat-fixing apparatus can be started with less power. That is, as the heat transfer efficiency is worse, the temperature difference becomes larger, so that a large amount of electric power is required to reach the outer surface temperature of 180 ° C. Those having a temperature difference of 20 ° C. or less were determined to be acceptable.

  Table 1 shows the evaluation results of these color mixing properties and heat conduction efficiency.

It is a typical sectional view of a heat conductive elastic member. It is a layer structure section schematic diagram of an example of a heat fixing member. It is a schematic diagram showing an example of a belt heating type heat fixing apparatus using a ceramic heater as a heating body.

Explanation of symbols

1 Matrix phase 2 Dispersed phase 3 Substrate (base layer)
4 Elastic layer 5 Release layer 11 Heat fixing member 12 Belt guide 13 Ceramic heater 14 Rigid stay for pressure 15 Pressure roller (pressure member)
16 Fixing nip 17 Contact-type temperature detection element on the inner surface 18 Contact-type temperature detection element on the outer surface 19 Unfixed toner 20 Recording material

Claims (9)

A matrix phase made of a resin containing a thermally conductive filler and a dispersed phase made of a material having a hardness lower than that of the matrix layer dispersed in the matrix phase, and a matrix phase thermal conductivity λa and a dispersed phase thermal conductivity λb, Is a thermal conductive elastic member, wherein λa ≧ 2λb and the overall thermal conductivity λ is in the range of 0.5 to 3.0 W · (m · K) ⁻¹ .   The thermally conductive elastic member according to claim 1, wherein the thermally conductive filler is made of an inorganic material. 3. The heat conductive elastic member according to claim 1, wherein the heat conductive filler has a heat conductivity of λf ≧ 10 W · (m · K) ⁻¹ . The heat conductive elastic member according to claim 1, wherein the heat conductive filler has a thermal conductivity of λf ≧ 100 W · (m · K) ⁻¹ . The recording material on which the unfixed image is formed is passed through a fixing nip formed by a heat fixing member having a heating unit and a pressure member, and the unfixed image is fixed on the recording material as a permanent image. A heating and fixing member incorporated in the heating and fixing device.
A heat fixing member comprising an elastic layer made of the heat conductive elastic member according to claim 1.   6. The heat fixing member according to claim 5, wherein the dispersed phase in the heat conductive elastic member is formed of an elastic material.   The heat fixing member according to claim 6, wherein the elastic material is silicone rubber powder.   The heat fixing member according to claim 5, wherein the matrix phase in the heat conductive elastic member is formed by curing a silicone rubber composition containing a heat conductive filler.   A heat-fixing apparatus comprising the heat-fixing member according to claim 5.

Images