JP4911674B2 - Heat fixing member and heat fixing device - Google Patents

Description

  In the present invention, a sheet-like recording material is sandwiched and conveyed at a pressure nip portion between a heat fixing member and a pressure member to heat the recording material, and an unfixed toner image on the recording material is melted and fixed. The present invention relates to a heat fixing member in a heat fixing device and a heat fixing device including the heat fixing member.

  In general, in a heat fixing device used in an electrophotographic system, a heating roller and another roller are pressed against each other, or a film or belt held on a pressure stay provided with a heating device and a roller are pressed against each other. Yes. Then, the heating roller, film or belt and the other roller rotate synchronously. A recording material holding an unfixed toner image is introduced into this pressure contact portion and heated, the unfixed toner image is melted, and then cooled and solidified to fix the image on the recording material. .

  A roller, a film, or a belt on the side where an unfixed toner image held on a recording material comes into contact is called a heat fixing member, and is called a fixing roller, a fixing film, a fixing belt, or the like depending on the form.

  These heat fixing members are generally provided with a heat generating mechanism inside as a heat source. Then, heat is supplied from the inner surface side, and the recording material in contact with the outermost surface of the heat fixing member is heated.

  Many of the heat fixing members basically have a heat-resistant elastic layer formed on a roller, film or belt-like substrate.

  This elastic layer is often formed from a heat-resistant rubber material such as silicone rubber or fluororubber, but these heat-resistant rubber materials are inferior in thermal conductivity, so when transferring heat from a heat source to the recording material. It becomes thermal resistance. Therefore, in order to increase the thermal conductivity of the heat-resistant rubber material, it is attempted to ensure heat transfer performance of the elastic layer by blending inorganic particles having high thermal conductivity such as alumina, zinc oxide, silicon carbide, etc. Although effective, there is an insufficient point to cope with the recent increase in the speed of recording apparatuses.

  Therefore, in Japanese Patent Application Laid-Open No. 2002-268423 (Patent Document 1), silicone rubber is used as the elastic layer rubber of the heat fixing member, and a small amount of vapor grown carbon fiber is blended to prevent oxidation deterioration and thermal conductivity. There has been proposed a method of trying to improve the above. In Japanese Patent Laid-Open No. 2002-351243 (Patent Document 2), carbon fiber is blended in the elastic layer, the thermal conductivity in the longitudinal direction of the roller is improved, the temperature distribution in the longitudinal direction is improved, and a uniform fixed image is obtained. The method of obtaining is also proposed.

  However, in the method described in Patent Document 1, since the inside of the vapor grown carbon fiber is in a hollow state, the thermal conductivity that can cope with the increase in speed cannot be secured. Moreover, in the method of Patent Document 2, since the carbon fibers are oriented in the longitudinal direction with respect to the member, the thermal conductivity in the longitudinal direction is sufficiently ensured, but in the thickness direction, the heat conductivity is improved. Since no heat flow path was formed, sufficient thermal conductivity could not be secured. As a result, in any case, the amount of heat given to the object to be heated is insufficient at the pressure contact part in the fixing device, and the pressure contact part dwell time (duel time) is shortened by increasing the speed. There is a problem that the toner image is not sufficiently melted and the glossiness (gloss) of the image becomes insufficient.

In recent years, image forming apparatuses have been increased in speed and size, and heat fixing devices are required to be able to cope with a further reduction in due time. Heat fixing members include a heat source to a heated object. Further improvement in heat transfer characteristics is desired.
JP 2002-268423 A JP 2002-351243 A

  The object of the present invention is to further improve the thermal conductivity in the thickness direction of the elastic layer, to efficiently supply heat to the heated body (recording material), and high glossiness even during high-speed printing. It is an object of the present invention to provide a heat fixing member capable of obtaining a fixed image having the above.

  Another object of the present invention is to provide a heat fixing member capable of obtaining a uniform image.

  It is another object of the present invention to provide a high-performance heat fixing device capable of transferring sufficient heat to an unfixed toner image even when the due time is shortened.

The present invention relates to a heat fixing member of cylindrical seamless type having an elastic layer, the elastic layer comprises an elastic material, and a carbon fiber as well as orientation inhibitory components are dispersed in the elastic material, the carbon The orientation of the fiber in the plane direction of the elastic layer is inhibited by the orientation-inhibiting component, and the orientation-inhibiting component is a particle, and the weight-average particle size is R (μm). The relationship between the diameter R (μm) and the average fiber diameter D (μm) of the carbon fiber satisfies 0.5 ≦ R / D ≦ 10, and the thermal conductivity in the thickness direction of the elastic layer is 1.0 W. / (M · K) or more is provided.

  Furthermore, the present invention provides a heat fixing device comprising the heat fixing member described above.

  In the heat-fixing member of the present invention, since the elastic layer has sufficient heat conductivity in the thickness direction, the heat transfer effect from the heater to the object to be heated is improved. Improvement in the gloss performance of the fixed image is achieved without significantly increasing the set temperature in the heat source of the fixing device. In addition, when a component that inhibits the orientation of carbon fibers (orientation-inhibiting component) is blended in the elastic layer, carbon fibers that are easily oriented in the in-plane direction of the elastic layer are randomly oriented so that the carbon fiber to the elastic layer The thermal conductivity in the thickness direction can be improved without increasing the blending amount. In other words, even if the carbon fiber content in the elastic layer is about the same as the conventional case, that is, in a range where the hardness of the elastic layer does not become too high, the heat transfer efficiency from the heater to the elastic layer surface is improved. Even during high-speed printing, improvement in gloss performance in a fixed image can be achieved without significantly increasing the set temperature in the heat source of the heat fixing device.

  In FIG. 1, which is a partial cross-sectional view showing the layer structure of the heat fixing member of the present invention, reference numeral 1 denotes a base material made of a material having excellent heat resistance and mechanical strength, on which an elastic layer 2 is formed. Further, a surface layer (release layer) 3 provided as necessary is formed on the elastic layer 2.

  The base material 1 is a roll-type or belt-like seamless cylindrical type, and the material is not particularly limited as long as the material is excellent in heat resistance and mechanical strength. For example, in the case of a roll, metals such as aluminum, iron, copper and nickel; alloys such as stainless steel and brass; ceramics such as alumina and silicon carbide are used. In addition to these materials, the base material suitable for the belt-shaped member includes, for example, polyethylene terephthalate, polybutylene naphthalate, polyester, thermosetting polyimide, thermoplastic polyimide, polyamide, polyamideimide, polyacetal, polyphenylene sulfide, and the like. Resin material is mentioned. Note that conductive resin such as metal powder, conductive oxide powder, and conductive carbon may be added to the base resin to impart conductivity. Among these, a polyimide film added with carbon black is preferable.

  The elastic layer 2 is formed on the substrate 1 with a uniform thickness and can be used in any thickness and shape useful as a heat fixing member. And in this invention, it is essential that the carbon fiber 2b is disperse | distributed and formed in the heat resistant elastic material 2a (refer FIG. 1).

  As the heat resistant elastic material 2a, a heat resistant rubber material such as silicone rubber or fluorine rubber can be used. When silicone rubber is used as the heat resistant elastic material, addition type silicone rubber is preferred from the viewpoint of availability and ease of processing. If the viscosity of the raw rubber is too low before the raw rubber is cured, dripping occurs during processing, and if it is too high, mixing and dispersion become difficult. Therefore, a raw rubber of about 0.1 to 1000 Pa · s is preferred. Raw material rubber in the range of ˜500 Pa · s is practically used.

  The carbon fiber 2b has a role as a filler for ensuring the thermal conductivity of the elastic layer, and is dispersed in the elastic material to form a heat flow path, which is efficient from the heat source side to the object to be heated. It is possible to supply heat. In addition, since the carbon fiber has a fiber shape, when it is kneaded with a liquid elastic material before curing, the carbon fiber is easily oriented in the flow direction, that is, in the plane direction during molding. In this case, although the thermal conductivity in the surface direction of the elastic layer can be increased, the effect of improving the thermal conductivity in the thickness direction of the elastic layer is reduced. Therefore, it is preferable to suppress the orientation of the carbon fiber and improve the thermal conductivity in the thickness direction. In the present invention, in addition to the addition of carbon fiber, in order to inhibit the orientation of the carbon fiber, it is preferable to add an orientation-inhibiting component 2c such as silica, alumina or iron oxide as shown in FIG. By using the orientation-inhibiting component, the thermal conductivity in the thickness direction of the elastic layer can be increased without excessively increasing the carbon fiber. Moreover, you may add protective materials of heat resistant elastic materials, such as a heat stabilizer and antioxidant, to an elastic layer.

  As the shape of the carbon fiber, the average fiber diameter D is preferably 1 μm or more from the viewpoint of securing a thick heat flow path, and the average fiber length L is preferably 1 μm or more from the viewpoint of forming a long heat flow path. preferable. Further, in the carbon fiber having a fiber length of 1 μm or more in order to relax the orientation during molding, the number of fibers having a fiber length in the range of 1 to 50 μm is preferably 80% or more, and the fiber length is 1 to 50 μm. The number of fibers in the range is preferably 80 to 95%. That is, the heat flow in the elastic layer is improved by setting the average fiber diameter D to 1 μm or more, and the heat flow path in the elastic layer is lengthened by setting the average fiber length L to 1 μm or more. The thermal conductivity of can be improved. In addition, by setting the number of fibers having a fiber length of 1 to 50 μm to 80% or more, the orientation of the carbon fibers during the elastic layer molding can be relaxed and the thermal conductivity in the thickness direction can be improved. Furthermore, it becomes possible to efficiently prevent the elastic layer from becoming hard by setting the number of fibers having a fiber length of 1 to 50 μm to 80 to 95%.

As such a carbon fiber, a pitch-based carbon fiber manufactured using petroleum pitch or coal pitch as a raw material is preferable because of its thermal conductivity. Further, it is preferable to use a material having a high purity and a density of 2.1 g / cm ³ or more, in which the internal graphite crystal structure is densely formed. When pitch-based carbon fibers are used, the heat conduction performance in the heat flow path in the elastic layer is improved. In general, there are many products with a true density of about 1.5 to 2.0 g / cm ³ on the market. In the present invention, however, the carbon crystal structure is particularly dense and the true density is 2 When the carbon fiber of 1 g / cm ³ or more is used, it is possible to further improve the heat conduction performance in the heat flow path in the elastic layer. The true density of the carbon fiber can be measured by using, for example, a dry automatic densimeter (trade name: Accupic 1330-1, manufactured by Shimadzu Corporation).

  Examples of the alignment inhibiting component 2c blended with the carbon fiber include metal oxides (for example, aluminum oxide, zinc oxide, quartz), metal nitrides (for example, boron nitride, aluminum nitride), metal carbides (for example, silicon carbide), A metal hydroxide (for example, aluminum hydroxide) can be illustrated. These can be used in the form of powder, granules, fibers, scales, spheres, needles, whiskers, and tetrapots. Among these, it is more preferable to use granular aluminum oxide (alumina) in view of high thermal conductivity, uniformity of shape, ease of blending into an elastic material (for example, silicone rubber), and the like.

  In order to effectively inhibit the orientation of the carbon fiber, when the weight average particle diameter of the orientation inhibiting component such as alumina particles is expressed as R (μm) and the average fiber diameter of the carbon fiber is expressed as D (μm), 0 It is preferable that the relationship is 5 ≦ R / D ≦ 10. By satisfying the above relationship for the weight average particle diameter R of the orientation-inhibiting component, it is not necessary to fill a large amount of particles in order to inhibit the orientation of the carbon fiber, and the heat transfer path by the carbon fiber is improved. Can be secured. That is, by setting the average fiber diameter D of the carbon fiber and the weight average particle diameter R of the orientation-inhibiting component as described above, it becomes possible to form an elastic layer having a lower hardness and ensure good image uniformity. However, the orientation of the carbon fiber during the elastic layer molding can be further relaxed, and the thermal conductivity in the thickness direction can be effectively improved.

  The weight average particle diameter R of the orientation-inhibiting component can be measured using, for example, a laser diffraction type particle size distribution measuring device (trade name: SALD-7000, manufactured by Shimadzu Corporation). Moreover, the average fiber diameter D of carbon fiber can be measured with a flow type particle image analyzer (trade name: FPIA-3000, manufactured by Sysmex Corporation), for example.

  Moreover, about the compounding quantity of a carbon fiber and an orientation inhibition component, it is preferable that the total volume filling rate is 20 to 60% with respect to the volume of an elastic material. Thereby, sufficient thermal conductivity can be provided in the thickness direction of the elastic layer while preventing an increase in the hardness of the elastic layer.

  As a method for confirming the number distribution of carbon fibers, it is possible to confirm by measuring the fiber length of 1000 or more individuals with a fiber length of 1 μm or more included in an arbitrary viewing angle using a scanning electron microscope. is there. The method for confirming the number distribution of carbon fibers contained in the elastic material is as follows. That is, a sample piece of an elastic layer containing carbon fiber is put in a muffle furnace in an aluminum container, heated at 500 ° C. for 1 hour, and then the residue in the aluminum container is taken out and ultrasonically stirred in methyl ethyl ketone. It can be confirmed by filtering and measuring the carbon fiber contained in the filtrate with a scanning electron microscope. In the present invention, image analysis software Image-Pro Plus (trade name) manufactured by Media Cybernetics was used for the measurement work from the captured image. The blending amount of the carbon fiber and the alignment-inhibiting component contained in the elastic material can also be confirmed by the above method using a scanning electron microscope.

  A method for forming the elastic layer 2 is not particularly limited, but generally, a molding method such as mold molding or coat molding can be used. Moreover, it is also possible to use the ring coat method disclosed in Japanese Patent Laid-Open No. 2003-190870 and Japanese Patent Laid-Open No. 2004-290853, and these methods can be used to form a seamless shape. In addition, as thickness of an elastic layer, 0.05-5 mm is preferable, for example, it is preferable that it is about 2 mm.

  The elastic layer has a hardness (hereinafter referred to as “ASKER”) measured using an ASKER-C type hardness meter (trade name, manufactured by Kobunshi Keiki Co., Ltd.) in accordance with JIS K7312 and SRIS0101 standards from the viewpoint of ensuring uniformity of a fixed image. -C hardness) and those at 1 to 50 degrees are preferable. By setting the ASKER-C hardness of the elastic layer within this range, the elastic layer of the heat fixing member can easily follow the unevenness of the recording material and the toner image, and sufficient image uniformity can be ensured. In addition, in the sample which cannot ensure sufficient thickness for measuring ASKER-C hardness, it cuts out only an elastic layer and measures by overlapping and measuring.

  Further, the thermal conductivity in the thickness direction of the elastic layer can be measured with a steady-state thermal conductivity measuring device AUTOΛ HC-110 (trade name, manufactured by Eihiro Seiki Co., Ltd.). At this time, the upper and lower plate temperatures are set to 25 ± 2 ° C., and if necessary, several samples are overlapped so that there is no gap, and the sample is set and measured so that the sample thickness is 6 mm or more. In addition, the average value of the value measured with the upper and lower plates is employ | adopted for the thermal conductivity of an elastic layer.

  The elastic layer in the heat-fixing member of the present invention must have a thermal conductivity in the thickness direction of 1.0 W / (m · K) or more when measured as described above. More preferably, it is 2.0 W / (m · K) or more. The gloss layer has a thermal conductivity of 1.0 W / (m · K) or higher in the thickness direction of the elastic layer so that good gloss performance can be achieved even during high-speed printing, and is 2.0 W / (m · K) or higher Is more preferable.

  The release layer 3 is often formed of silicone rubber, fluororubber, fluororesin, or the like, but fluororesin is preferable from the viewpoint of mold release properties. The formation method is not particularly limited, but generally, a method of covering the elastic layer 2 with a release layer material molded into a seamless tube shape, fine particles of the material and its dispersion liquid are applied to the elastic layer 2. Examples include a method of coating the outer surface, heating and melting, and forming a release layer by film formation. The thickness of the release layer is not particularly limited, but is preferably 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 purposes of slidability, heat absorption, heat generation, releasability, etc. In order to improve the slidability, a layer made of polyimide, polyamideimide, fluororesin, or the like may be provided on the inner surface. The order in which these layers are formed is not particularly limited, and may be appropriately changed depending on the convenience of each process.

Hereinafter, a heat fixing apparatus including the heat fixing member of the present invention will be described.

  FIG. 2 is a schematic cross-sectional view of a heat fixing apparatus using a roller-shaped heat fixing member as the heat fixing member.

  This heat fixing device includes a pair of rotating rollers including a fixing roller 11 as a heat fixing member and a pressure roller 12 pressed against the fixing roller 11, and a nip is formed between the rollers. Each of these rollers has a built-in heater 13 serving as a heat source. In such a heat-fixing apparatus, for example, when both the fixing roller 11 and the pressure roller have an outer diameter of 60 mm and are pressed against each other with a constant pressure, the nip width is usually set to 5 to 10 mm.

  On the fixing roller 11 side, an oil application device that applies silicone oil or the like as a release agent to the surface, a cleaning device that removes deposits such as offset toner and paper dust attached to the surface of the fixing roller, and a temperature control element that controls temperature Etc. may be installed.

  The surface on which the image is formed with the unfixed toner T faces the fixing roller 11, and a recording target to be heated is a pressure contact portion formed by the fixing roller 11 and the pressure roller 12 adjusted to a constant temperature. The material P is conveyed, the toner is heated and pressurized, and fixed on the recording material P.

  The fixing roller 11 has a metal core 14 made of cylindrical aluminum or the like as a base material, and is further provided with an elastic layer 15. A release layer such as a fluororesin having a thickness of about 50 μm may be provided on the elastic layer 15 as necessary. Further, in the case of such a roller-shaped heat fixing member, a core metal having a thickness of about 2 mm can be used, and a roller outer diameter can be set to about 60 mm.

  On the other hand, the pressure roller 12 is also formed by forming an elastic layer on a metal core bar made of aluminum or the like and, if necessary, a release layer, like the fixing roller. That is, the pressure roller 12 may be the same as the fixing roller 11.

  FIG. 3 is a schematic cross-sectional view of a heat fixing device using a belt-shaped heat fixing member.

  In this heat fixing device, a fixing belt 21 having a seamless shape as a heat fixing member forms a fixing nip portion 26 with a pressure member 25. A fixing belt 21 is provided with a belt guide member 22 formed of a heat-resistant and heat-insulating resin or ceramic to hold the fixing belt 21, and the belt guide member 22 and the fixing belt. A heat source 23 such as a ceramic heater is provided at a position in contact with the inner surface of 21. The heat source 23 is fitted and fixedly supported in a groove provided along the longitudinal direction of the belt guide member 22, and generates heat when energized. The seamless-shaped fixing belt 21 is loosely fitted on the belt guide member 22. The pressurizing rigid stay 24 is inserted inside the belt guide 22.

  The heat-fixing belt 21 is formed by forming an elastic layer 21b on the outer surface of the belt base 21a and further coating the outer surface with a fluororesin tube 21c as a release layer.

  The pressure member 25 is an elastic pressure roller, and is usually a rod-shaped cored bar 25a made of stainless steel or the like provided with an elastic layer 25b such as silicone rubber to reduce the hardness. Is rotatably supported between the front side and the rear chassis side plate (not shown). The elastic pressure roller is usually coated with a fluororesin tube of about 50 μm as the surface layer 25c in order to improve surface properties and releasability. By pressing the pressure springs (not shown) between the both ends of the pressure rigid stays 24 and the spring receiving members (not shown) on the apparatus chassis side, the pressing rigid stays 24 have a pressing force. Has been granted. As a result, the lower surface of the ceramic heater 23 disposed on the lower surface of the belt guide member 22 and the upper surface of the pressure member 25 are pressed against each other with the fixing belt 21 interposed therebetween, so that the above-described fixing nip portion 26 is formed.

  The recording material P, which is a heated body on which an image is formed with the unfixed toner T, is nipped and conveyed in the fixing nip portion 26, whereby the toner image is heated and pressurized to be fixed on the recording material.

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

  First, carbon fibers and fillers used in the following examples and comparative examples are shown.

[Filler]
・ 01M: pitch-based carbon fiber, trade name: XN-100-01M, manufactured by Nippon Graphite Fiber Co., Ltd., average fiber diameter D: 5 μm, average fiber length L: 10 μm, number ratio of fibers having a fiber length of 1-50 μm: 100 %, True density: 2.1 g / cm ³ .
15M: pitch-based carbon fiber, trade name: XN-100-15M, manufactured by Nippon Graphite Fiber Co., Ltd., average fiber diameter D: 10 μm, average fiber length L: 150 μm, number ratio of fibers having a fiber length of 1-50 μm: 70 %, True density: 2.2 g / cm ³ .
・ 25M: pitch-based carbon fiber, trade name: XN-100-25M, manufactured by Nippon Graphite Fiber Co., Ltd., average fiber diameter D: 10 μm, average fiber length L: 250 μm, number ratio of fiber length 1-50 μm: 10 %, True density: 2.2 g / cm ³ .
A10S: high-purity true spherical alumina, trade name: Aruna beads CB-A10S, manufactured by Showa Titanium Co., Ltd., weight average particle diameter R: 10 μm.

Example 1
A hydrogenated organopolysiloxane having at least two SiH bonds in one molecule with respect to both ends vinylated polydimethylsiloxane (weight average molecular weight 68000 (polystyrene conversion)), having a SiH group and a vinyl group of 2: 1. Addition-curing silicone rubber stock solution having a viscosity of 6.5 Pa · s (measured with a V-type rotational viscometer, rotor No. 4, 60 rpm) by adding a platinum compound as a catalyst to a proportion. Obtained.

  This addition-curing silicone rubber stock solution is uniformly blended and kneaded so that the pitch-based carbon fiber 01M is 31.1% by volume and the pitch-based carbon fiber 25M is 8.9% by volume. Thus, a silicone rubber composition 1 was obtained. The average fiber diameter D of the carbon fibers contained in the silicone rubber composition 1 was 6 μm, and the number ratio of fibers having a fiber length of 1 to 50 μm was 80%.

  This silicone rubber composition 1 was applied to the outer surface of a belt base material (thickness 35 μm, inner diameter 24 mm) formed of SUS304 with a thickness of 300 μm by a ring coating method, and heat cured at 200 ° C. for 4 hours to form an elastic layer Formed. Further, this outer surface was covered with a PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) tube (thickness 30 μm), and both ends were cut to obtain a heat fixing member 1 having a length of 230 mm in the longitudinal direction.

  Separately, an elastic layer was formed on the belt base material in the same manner as described above. The ASKER-C hardness measured in a state where the elastic layer was cut out and a plurality of layers were stacked so that the thickness was 6 mm or more was 35 degrees. Further, the thermal conductivity in the thickness direction of the cut out elastic layer was measured and found to be 2.3 [W / (m · K)]. The results are shown in Table 1.

Examples 2-9 and Comparative Examples 1-2
Heat fixing members 2 to 9 (Examples) and 10, 11 (Comparative) in the same manner as in Example 1 except that the carbon fibers or fillers shown in Table 1 below were used in the filling amounts shown in Table 1. Example) was prepared. Carbon fiber average fiber diameter D, average fiber length L, number ratio of fiber lengths of 1 to 50 μm, and ASKER-C hardness and heat conductivity of elastic layer of heat fixing member in silicone rubber composition Was measured. The results are shown in Table 1.

Comparative Examples 3 and 4
Heat fixing members 12 and 13 were produced in the same manner as in Example 1 except that the fillers shown in Table 1 below were used in the filling amounts shown in Table 1. The ASKER-C hardness and the thermal conductivity in the thickness direction of the elastic layers according to the heat fixing members 12 and 13 were measured. The results are shown in Table 1.

<Performance evaluation>
For the performance evaluation, the heat fixing device incorporating the heat fixing member produced above as a fixing belt of the heat fixing device shown in FIG. 3 is incorporated into a color laser printer (trade name: LBP-2410, manufactured by Canon Inc.). I used it. The pressurizing member used had an outer diameter of 24 mm and an elastic layer thickness of 3 mm.

  In a state where the pressure member is rotated in the direction of the arrow so that the moving speed of the surface becomes 200 mm / sec, energization is started to the ceramic heater, and the heating fixing member at a position 90 ° upstream from the fixing nip portion. The external surface temperature was monitored with a radiation thermometer (not shown), and the on / off timing of the electric power supplied to the ceramic heater was adjusted to stabilize the external surface temperature at 180 ° C.

Using the printer described above, an image was printed at 100% density on almost the entire surface using cyan toner and magenta toner on A4 size printing paper (trade name: PB PAPER GF-500, manufactured by Canon Inc., 68 g / m ² ). An image for evaluation was formed. Using the obtained images, the glossiness (75 ° gloss value) and glossiness uniformity were evaluated by the following methods. Table 1 shows the evaluation results.

<Glossiness>
Using a gloss meter PG-3D (incidence / reflection angle = 75 °) manufactured by Nippon Denshoku Co., Ltd., using black glass with a gloss level of 96.9 as a reference, at a position 5 cm from the leading edge of the evaluation image in the sheet passing direction. The glossiness (75 ° gloss value) was measured at the center.

<Glossiness uniformity>
Whether or not gloss unevenness was observed by five subjects was judged visually and evaluated according to the following criteria.
A: All five people judged that “the gloss unevenness was small”.
B: Four people judged that “the gloss unevenness was small”.
C: Three people judged that “the gloss unevenness was small”. It is an acceptable range.
D: The number of people who judged that “the gloss unevenness was small” was 2 or less.

  In the heat fixing member 1 (Example 1), relatively short carbon fibers having a fiber length in the range of 1 to 50 μm are filled without being oriented in the elastic layer, while the fiber length is relatively long such as 50 μm or more. The carbon fiber forms a long heat transfer path in the elastic layer. As a result, a high thermal conductivity is achieved with a relatively small filling amount, and an increase in the hardness of the elastic layer is also suppressed. As a result, the thermal conductivity in the thickness direction of the elastic layer is as extremely high as 2.3 W / (m · K), and sufficient heat can be supplied to the object to be heated and the toner image, resulting in excellent gloss performance. It is expressed. Furthermore, since the hardness of the elastic layer is sufficiently soft, it follows the unevenness of the surface of the heated object and the toner image, and an extremely good gloss uniformity can be secured over the entire surface of the heated object.

  In the heat fixing member 2 (Example 2), the fiber length distribution of the carbon fiber is kept as it is, and the blending amount is halved to improve the flexibility of the elastic layer compared to the heat fixing member 1. The thermal conductivity in the thickness direction of the elastic layer was sufficient at 1.2 W / (m · K), and extremely good results were obtained with respect to gloss performance, particularly gloss uniformity.

  In the heat fixing member 3 (Example 3), the thermal conductivity in the thickness direction of the elastic layer is 1.5 W / (m · K), the ASKER-C hardness is flexible at 27 degrees, and the gloss performance is extremely high. Good gloss uniformity was obtained.

  In the heat fixing member 4 (Example 4), the thermal conductivity in the thickness direction of the elastic layer is as extremely high as 2.0 W / (m · K), and as a result of sufficient flexibility, excellent gloss performance and extremely good Gloss uniformity was secured.

  Although the heat fixing member 5 (Example 5) did not reach the heat fixing member 4, a sufficiently excellent gloss performance was obtained, and extremely good gloss uniformity was obtained.

  In the heat fixing member 6 (Example 6), as a result of using carbon fibers having only a relatively short fiber length in the range of 1 to 50 μm, although the amount used is small, Although the flexibility of the elastic layer was not as high as that of the heat fixing members 1 to 5, it was a good result.

  In the heat fixing member 7 (Example 7), the filling amount of the carbon fiber in the elastic layer is reduced as compared with the heat fixing member 6, the hardness of the elastic layer is reduced, and extremely good gloss uniformity is achieved. did.

  Also in the heat fixing member 8 (Example 8) and the heat fixing member 9 (Example 9), the thermal conductivity in the thickness direction is 1.0 W / (m · K) or more by blending the carbon fiber in the elastic layer. It ensures the gloss uniformity within the allowable range while ensuring good gloss performance.

  On the other hand, in the heat-fixing member 10 (Comparative Example 1) and the heat-fixing member 11 (Comparative Example 2), the amount of carbon fiber to be a heat flow path in the elastic layer is small, so that sufficient heat conductivity in the thickness direction is ensured. As a result, sufficient gloss performance could not be secured.

  Further, when the heat fixing member 12 prepared in Comparative Example 3 is used, alumina particles are added to the elastic layer at a filling ratio of 50% in order to obtain a desired gloss performance, but the hardness becomes high. Therefore, the unevenness of the surface of the object to be heated and the toner image could not be tracked, and uneven gloss occurred.

  Further, in the heat fixing member 13 (Comparative Example 4), the filling ratio of the alumina particles in the elastic layer is reduced to 30% to reduce the hardness, and the reduction of gloss unevenness is attempted. As a result, the thermal conductivity decreased, so that sufficient gloss performance could not be secured.

  The carbon fibers and orientation-inhibiting components used in the following examples and comparative examples are shown.

[Carbon fiber]
・ 25M: pitch-based carbon fiber, trade name: XN-100-25M, manufactured by Nippon Graphite Fiber Co., Ltd., average fiber diameter D: 10 μm, average fiber length L: 250 μm, number ratio of fiber length 1-50 μm: 10 %, True density: 2.2 g / cm ³ .
15M: pitch-based carbon fiber, trade name: XN-100-15M, manufactured by Nippon Graphite Fiber Co., Ltd., average fiber diameter D: 10 μm, average fiber length L: 150 μm, number ratio of fibers having a fiber length of 1-50 μm: 70 %, True density: 2.2 g / cm ³ .
10M: pitch-based carbon fiber, trade name: XN-100-10M, manufactured by Nippon Graphite Fiber Co., Ltd., average fiber diameter D: 10 μm, average fiber length L: 100 μm, number ratio of fibers having a fiber length of 1-50 μm: 80 %, True density: 2.2 g / cm ³ .
・ 05M: pitch-based carbon fiber, trade name: XN-100-05M, manufactured by Nippon Graphite Fiber Co., Ltd., average fiber diameter D: 10 μm, average fiber length L: 50 μm, number ratio of fibers having a fiber length of 1-50 μm: 90 %, True density: 2.2 g / cm ³ .
・ 01M classification: Pitch-based carbon fiber (trade name: XN-100-01M, manufactured by Nippon Graphite Fiber Co., Ltd., average fiber diameter D: 5 μm, average fiber length L: 10 μm, number ratio of fiber length 1-50 μm: 100%, true density: 2.1 g / cm ³ ), average fiber diameter D: 3 μm, average fiber length L: 5 μm, number ratio of fiber length 1-50 μm: 100%, true density 2 .1 g / cm ³ .

(Orientation-inhibiting component)
A50S: Aluminum oxide particles, trade name: high-purity true spherical alumina Aruna beads CB-A50S, manufactured by Showa Titanium Co., Ltd., weight average particle size R: 50 μm.
A30S: Aluminum oxide particles, trade name: high-purity spherical alumina, Aruna beads CB-A30S, manufactured by Showa Titanium Co., Ltd., weight average particle size R: 30 μm.
A10S: Aluminum oxide particles, trade name: high purity spherical alumina, Aruna beads CB-A10S, manufactured by Showa Titanium Co., Ltd., weight average particle size R: 10 μm.
A50S classification: weight average particle diameter R: 45 μm obtained by classifying aluminum oxide particles A50S.
A10 classification: Aluminum oxide particles (trade name: high-purity spherical alumina, Aruna beads CB-A10, manufactured by Showa Titanium Co., Ltd., weight average particle diameter R: 10 μm), and weight average particle diameter R: 5 μm Things.
A05S classification 3: Aluminum oxide particles (trade name: high-purity spherical alumina, Aruna beads CB-A05S, manufactured by Showa Titanium Co., Ltd., weight average particle size R: 3 μm) 3 μm.
A05S classification 2: Aluminum oxide particles (trade name: High-purity spherical alumina Aluna beads CB-A05S, Showa Titanium Co., Ltd., weight average particle size R: 3 μm) 2 μm.
WZ: Zinc oxide whisker, trade name: Panatetra WZ-0501, manufactured by Matsushita Amtec Co., Ltd., weight average particle size R: 25 μm.

Example 10
A hydrogenated organopolysiloxane having at least two SiH bonds in one molecule with respect to both ends vinylated polydimethylsiloxane (weight average molecular weight 68000 (polystyrene conversion)), having a SiH group and a vinyl group of 2: 1. Addition-curing silicone rubber stock solution having a viscosity of 6.5 Pa · s (measured with a V-type rotational viscometer, rotor No. 4, 60 rpm) by adding a platinum compound as a catalyst to a proportion. Obtained.

  To this addition curable silicone rubber stock solution, the carbon fiber 15M is uniformly blended so that the volume ratio is 30% and the aluminum oxide particles A50S are 20% in volume ratio, and kneaded to form a silicone rubber composition. I got a thing.

  This silicone rubber composition was applied to the outer surface of a belt base material (thickness 35 μm, inner diameter 24 mm) made of SUS304 with a thickness of 300 μm by the ring coating method, and heated and cured at 200 ° C. for 4 hours to form an elastic layer. Formed. Further, this outer surface was covered with a PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) tube (thickness 30 μm), and both ends were cut to obtain a heat fixing member 15 having a length of 230 mm.

  Separately, an elastic layer is formed on the belt base material in the same manner as described above, a heat fixing member before the fluororesin tube is stacked is produced, the elastic layer is cut out, and a plurality of sheets are stacked so that the thickness is 6 mm or more. The ASKER-C hardness measured in the above state was 39 degrees. Further, the thermal conductivity in the thickness direction of the cut out elastic layer was measured and found to be 2.2 [W / (m · K)]. The results are shown in Table 2.

Examples 11-16, Comparative Examples 5-8
A silicone rubber composition was prepared in the same manner as in Example 10 except that the amount shown in Table 2 was added as the carbon fiber and the orientation-inhibiting component, and the heat fixing members 16 to 25 were prepared. . The ASKER-C hardness and thermal conductivity of the elastic layer of these heat fixing members were also measured and are shown in Table 2.

  The heat fixing members of Examples 10 to 16 and Comparative Examples 5 to 8 were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

  In the heat fixing member 15 (Example 10), the composition of the carbon fiber and the alumina particles and the relationship between the fiber diameter and the particle size (R / D = 5) are appropriate, and the alumina particles effectively adjust the orientation of the carbon fibers. It is considered that the thermal conductivity in the thickness direction of the elastic layer was extremely high at 2.2 W / (m · K). As a result, heat could be sufficiently supplied to the heated object and the toner, and as a result, excellent gloss performance could be exhibited. In addition, the elastic layer has low hardness and is soft enough to follow the unevenness of the surface of the heated object or toner image, and as a result, it was found that extremely good gloss uniformity was ensured over the entire surface of the heated object. It was.

  In the heat fixing member 16 (Example 11), the shape and the total volume filling rate of the carbon fibers and the alumina particles are the same as those of the heat fixing member 15, but as a result of changing the blending ratio, the heat conductivity in the thickness direction is 2. .1 W / (m · K) was sufficiently high, the gloss performance was excellent, the elastic layer was sufficiently soft, and the gloss uniformity across the entire surface of the heated object was extremely good.

  In the heat fixing member 17 (Example 12), since the alumina particles and the carbon fibers having the relationship of R / D = 3 are blended as described above, the thermal conductivity (1.4 W / (m Although K)) was reduced, the ASKER-C hardness was 35 degrees, and the obtained image also achieved a sufficiently excellent gloss performance and obtained extremely good gloss uniformity.

  In the heat fixing member 18 (Example 13), the alumina particles and the carbon fibers having a relationship of R / D = 1 are blended as shown in Table 2, so that the filler for ensuring heat conduction is reduced and the thickness direction is reduced. Although the thermal conductivity of AW was slightly reduced to 1.0 W / (m · K), the ASKER-C hardness was as small as 30 degrees, and excellent gloss performance and extremely good due to the relationship between thermal conductivity and flexibility High gloss uniformity.

  In both the heat fixing member 19 (Comparative Example 5) and the heat fixing member 20 (Comparative Example 6), the thermal conductivity in the thickness direction did not reach a desired value. Also, the gloss performance was lowered.

  As the heat fixing member 21 (Example 14), one in which the blended carbon fiber and the alumina particles are out of the desired relationship (0.5 ≦ R / D ≦ 10) (R / D = 0.3) is used. As a result, the interface area between the alumina particles and the silicone rubber increased, and as a result, the flexibility of the elastic layer did not reach the heat fixing members 15-20. However, since the thermal conductivity was high, excellent results were obtained for the gloss performance, and the gloss uniformity evaluation was acceptable.

  Also in the heat fixing member 22 (Example 15), R / D = 15, and the carbon fiber and the alumina particles are out of the desired relationship (0.5 ≦ R / D ≦ 10). The interfacial area of the rubber increased, and as a result, the flexibility of the elastic layer did not reach the heat fixing members 15-20. However, the gloss performance was at a sufficient level, and was also acceptable in the gloss uniformity evaluation.

  Even in the case of using the heat fixing member 23 (Comparative Example 7) and the heat fixing member 24 (Comparative Example 8), the relationship between the carbon fiber and the alumina particles is in a range outside 0.5 ≦ R / D ≦ 10. By blending as shown in Table 2, the thermal conductivity of the elastic layer did not reach the desired value. Also, the gloss performance was lowered.

  In the heat fixing member 25 (Example 16), a zinc pot whisker (WZ) having a tetrapot shape was used as a carbon fiber orientation-inhibiting component. However, the thermal conductivity and flexibility of the elastic layer ensure a desired level, Realizes excellent gloss performance and good gloss uniformity.

  As described above, as seen in Examples and Comparative Examples, a seamless type heat fixing member having an elastic layer containing carbon fiber and having a thermal conductivity in the thickness direction of 1.0 W / (m · K) or more is As a heat fixing member of the heat fixing device, it is possible to achieve good image uniformity while ensuring high gloss performance of a fixed image during high-speed printing.

  Furthermore, by adjusting the blending of carbon fibers, it becomes possible to design an elastic layer with higher thermal conductivity and lower hardness, and can achieve excellent gloss performance and image uniformity at the same time. A heat fixing device can be obtained.

  Further, by blending an orientation-inhibiting component together with the carbon fiber to inhibit the orientation of the carbon fiber, it is possible to obtain a heat-fixing apparatus that can obtain an image having even better gloss performance.

It is a fragmentary sectional view which shows the layer structure of a heat fixing member. It is a schematic cross-sectional view of a heat fixing device using a roller-shaped heat fixing member. 2 is a schematic cross-sectional view of a heat fixing device using a belt-shaped heat fixing member. FIG. It is a fragmentary sectional view which shows the layer structure of a heat fixing member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Elastic layer 2a Heat resistant elastic material 2b Carbon fiber 2c Orientation inhibition component 3 Surface layer (release layer)
DESCRIPTION OF SYMBOLS 11 Fixing roller 12 Pressure roller 13 Heater 14 Metal core 15 Elastic layer 21 Fixing belt 21a Belt base material 21b Elastic layer 21c Fluororesin tube 22 Belt guide member 23 Heat source (ceramic heater)
24 Pressurizing rigid stay 25 Pressurizing member 25a Stainless steel core metal 25b Silicone rubber elastic layer 25c Surface layer 26 Fixing nip portion T Unfixed toner P Recording material

Claims (13)

A seamless type cylindrical heat fixing member having an elastic layer,
The elastic layer includes an elastic material, a carbon fiber dispersed in the elastic material, and an orientation-inhibiting component,
The orientation of the carbon fiber in the plane direction of the elastic layer is inhibited by the orientation-inhibiting component,
When the orientation-inhibiting component is particles and the weight average particle diameter is R (μm), the relationship between the weight average particle diameter R (μm) and the average fiber diameter D (μm) of the carbon fiber is:
0.5 ≦ R / D ≦ 10
The filling,
A heat fixing member having a thermal conductivity in the thickness direction of the elastic layer of 1.0 W / (m · K) or more. The elastic layer is formed by applying a rubber composition in which the carbon fiber and the orientation-inhibiting component are dispersed in a stock solution of an elastic material to a cylindrical base material by a ring coating method and curing the rubber composition. The heat fixing member according to claim 1. The heat fixing member according to claim 1, wherein the elastic material is rubber. The heat fixing member according to claim 3, wherein the rubber is silicone rubber. Heat fixing member according to any one of claims 1-4 thickness direction of the thermal conductivity of the elastic layer is 2.0W / (m · K) or more. Heat fixing member according to any one of claims 1 to 5 average fiber diameter D of the carbon fiber is 1μm or more. Heat fixing member according to any one of claims 1 to 6 the average fiber length L of the carbon fibers is 1μm or more. The heat fixing member according to claim 7 , wherein the number of carbon fibers having an average fiber length of 1 µm or more and having a fiber length in the range of 1 to 50 µm is 80% or more. The heat fixing member according to claim 7 , wherein the number of carbon fibers having an average fiber length of 1 µm or more and having a fiber length in the range of 1 to 50 µm is 80 to 95%.   The heat fixing member according to claim 1, wherein the carbon fiber is a pitch-based carbon fiber. The carbon fiber, true density, heat fixing member according to any one of claims 1 to 10, which is 2.1 g / cm ³ or more carbon fibers. Heat fixing member according to any one of claims. 1 to 11 ASKER-C hardness of the elastic layer is 1 to 50 degrees. Heat fixing apparatus characterized in that it comprises a heat fixing member according to any one of claims 1 to 12.

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