JP2010271394A - Pressure member, method for manufacturing the pressure member, fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a pressure member capable of suppressing the occurrence of gloss unevenness of a fixed toner image while achieving shortening of rise time of a fixing device; a pressure roller; a method for manufacturing the pressure member; a fixing device; and an image forming apparatus. <P>SOLUTION: In a heat insulating layer 2d, many holes 2d2 having a 30 &mu;m or less hole diameter are formed to be dispersed so that porosity may be 45 to 65% in thermoplastic resin 2d1. Therefore, the heat insulating layer 2d having low thermal conductivity such as 0.1 W/mK or less is easily obtained even when the porosity of the holes 2d2 in the heat insulating layer is about 50%. As a result, a situation that heat from a fixing roller 1 press-contacting with the pressure roller 2 is transferred to a core member 2a to be radiated is suppressed, and generated heat of the fixing roller 1 is effectively used as quantity of heat for fixing, thereby achieving shortening of the rise time of the fixing device. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a pressure member for pressing a recording medium having an unfixed toner image on the surface thereof against a heated fixing rotator and fixing the unfixed toner image on the recording medium, and a method for manufacturing the pressure member And a fixing device and an image forming apparatus including the pressure member.

  In an image forming apparatus configured as an electronic copying machine, a printer, a facsimile machine, or a multifunction machine having at least two functions, an unfixed toner image formed on a recording medium such as a transfer paper or a resin sheet is used. A fixing device that uses heat and pressure to fix on a recording medium is used. As such a fixing device, a fixing device that passes a recording medium carrying a toner image between a heated fixing roller and a pressure roller and fixes the toner image on the recording medium has been widely used. Has been.

  FIG. 9 is a cross-sectional view showing a conventional example of this type of fixing device. In this conventional fixing device, as shown in FIG. 9, a metal hollow with a heater 3 incorporated therein is used to heat and pressurize an unfixed toner image T formed on a recording medium P such as transfer paper. A fixing roller 1 is used in which a heat-resistant elastic body layer 1b made of silicone rubber is formed on the surface of a cylindrical core member 1a. The pressure roller 2 that presses the fixing roller 1 via the recording medium P presses the fixing roller 1 with a spring 4 or the like. The pressure roller 2 has an elastic layer 2b made of silicone rubber on the surface of the metal core member 2a. The elastic layer 2b of the pressure roller 2 and the elastic layer 1b of the fixing roller 1 The recording medium P is pressed while being heated at the nip portion N between the fixing roller 1 and the pressure roller 2 formed by the above process so that the unfixed toner image is melted and softened and fixed (fixed) on the surface of the recording medium P. It has become. By using the fixing roller 1 having the elastic layer 1b and the pressure roller 2 having the elastic layer 2b, fixing is performed while following the uneven surface of the recording medium P having an unfixed toner image at the nip portion N. The elastic layers of the roller 1 and the pressure roller 2 are elastically deformed and appropriately heated and pressed to fix the toner image satisfactorily.

  However, when the pressure roller 2 having such an elastic body layer 2b made of silicone rubber is used, the elastic body layer 2b absorbs the heat of the fixing roller 1 that generates heat, and when the fixing operation starts, the surface of the fixing roller 1 There is a problem in that the startup time until the temperature rises to a predetermined temperature becomes long, which causes inconvenience to the user. In order to cope with such problems, it has been proposed to use a pressure roller in which a hard heat insulating layer in which hollow glass beads are bound with a resin or a silicon-based adhesive is formed on the surface of the core member as the pressure roller. (For example, refer to Patent Document 1).

  However, in the fixing device described in Patent Document 1, although the rise time of the fixing device can be shortened, since the hollow glass beads are mixed in the hard heat insulating layer, the minute hardness of the pressure roller during fixing is reduced. The distribution affects the problem that gloss unevenness occurs.

  The present invention has been made in consideration of the above circumstances, and a pressure member and a pressure roller that can suppress the occurrence of uneven glossiness of a fixed toner image while enabling the rise time of the fixing device to be shortened. An object of the present invention is to provide a pressure member manufacturing method, a fixing device, and an image forming apparatus.

  In order to solve the above-described problem, the invention described in claim 1 is configured such that a recording medium having an unfixed toner image on a surface thereof is pressed against a fixing rotator having an elastic layer, and the unfixed toner image is In the pressure member to be fixed to the recording medium, the pressure member has a hole having a hole diameter of 30 μm or less on the base material, and the heat setting is set in the range of 45 to 65%. It is characterized by forming a heat insulating layer mainly composed of a conductive resin.

  According to a second aspect of the present invention, in the pressurizing member according to the first aspect, the pores are formed by already expanded particles.

  According to a third aspect of the present invention, in the pressurizing member according to the first or second aspect, the base material is a core member that has a rotation shaft and is rotatable.

  According to a fourth aspect of the present invention, there is provided the pressure member according to any one of the first to third aspects, wherein a release layer containing a fluororesin is provided on a surface in contact with the recording medium. .

  The invention according to claim 5 provides a coating layer containing the foamed particles in an uncured resin on the substrate, and the coating layer is heated at a predetermined temperature to primarily cure the uncured resin. Then, the pressure member according to any one of claims 1 to 3, wherein the pressure member according to any one of claims 1 to 3 is obtained by heating at a temperature higher than the predetermined temperature and performing secondary curing to form a heat insulating layer. This is a manufacturing method.

  Further, the invention of claim 6 provides a coating layer containing the foamed particles in an uncured resin on a substrate, and the coating layer is heated at a predetermined temperature to primarily cure the uncured resin, 5. The pressurization according to claim 4, wherein heating is performed at a temperature higher than the predetermined temperature to perform secondary curing to form a heat insulating layer, and a release layer containing a fluororesin is further bonded onto the heat insulating layer. A method for producing a pressure member, comprising: obtaining a member.

  According to a seventh aspect of the present invention, a fixing rotator to be heated and a recording medium having an unfixed toner image on the surface thereof are pressed against the fixing rotator, and the unfixed toner image is applied to the recording medium. A fixing device including a pressure member for fixing, wherein the pressure member is the pressure member according to any one of claims 1 to 4.

  The fixing device according to claim 8 is characterized in that, in the fixing device according to claim 7, the fixing rotator is mainly composed of a silicone rubber containing carbon fibers and bubbles of an open cell structure on the surface of a core member having a rotating shaft. It is a fixing rotating body in which an elastic layer is formed.

  According to a ninth aspect of the present invention, there is provided an image carrier that forms an electrostatic latent image on the surface, and development that supplies toner to the electrostatic latent image on the surface of the image carrier and converts the electrostatic latent image into a toner image. An apparatus, a transfer device for transferring the toner image on the surface of the image carrier to the surface of the recording medium, and a toner image transferred to the surface of the recording medium by the transfer device to heat and press the toner image on the surface of the recording medium. An image forming apparatus provided with a fixing device for fixing, wherein the fixing device is the fixing device according to claim 7 or 8.

  According to the present invention, the pressurizing member has, on the base material, a hole mainly composed of a thermosetting resin and having a hole diameter of 30 μm or less and a porosity of 45 to 65%. The pressure member, the pressure roller, and the pressure member capable of suppressing the occurrence of gloss unevenness in the fixed toner image while enabling the rise time of the fixing device to be shortened by forming the heat insulating layer set to Manufacturing method, fixing device, and image forming apparatus can be provided.

1 is a cross-sectional view illustrating a schematic configuration of a fixing device according to an embodiment of the present invention. It is an expanded sectional view of the A section of FIG. It is an expanded sectional view of the B section of FIG. It is sectional drawing of the elastic body layer in which the conventional bubble is not made into continuous bubbles. It is sectional drawing of the core member used with the fixing roller shown in FIG. It is sectional drawing which shows the modification of the circumference protrusion of the core member shown in FIG. It is an expanded sectional view of the C section of FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 10 is a cross-sectional view illustrating a schematic configuration of a conventional fixing device.

  As a result of studying the suppression of occurrence of gloss unevenness in a fixed toner image while enabling the rise time of the fixing device to be shortened, the present inventors have a hole having a hole diameter of 30 μm or less and a porosity of When a pressure member having a heat insulating layer mainly composed of a thermosetting resin set within a range of 45 to 65% is used on the substrate, the rise time of the fixing device can be shortened. It has been found that it is possible to suppress the occurrence of gloss unevenness in a fixed toner image.

  That is, in the hard heat insulating layer in which the hollow glass beads described in the above-mentioned Patent Document 1 are mixed in the resin, it is possible to exert a good heat insulating effect, but the hollow glass bead particles forming the pores Since it has a relatively large hole diameter of 100 μm or more, the hardness distribution of the pressure member becomes wider, the distribution of the pressing force that presses the fixing roller becomes wider, and the pressing force against the recording medium at the nip portion with the fixing roller Was found to be uneven and gloss unevenness. As a result of further investigation on the occurrence of such gloss unevenness, pores are included in the case of a heat insulating layer made of a thermosetting resin having pores of 30 μm or less, particularly 20 μm or more and 30 μm or less. Maintains a low thermal conductivity appropriately and has good heat insulation, sharpness of the pressure member hardness distribution, uniform pressing force against the recording medium at the nip with the fixing roller, and uneven gloss It has been found that the occurrence of odor can be satisfactorily suppressed.

  In particular, by setting the volume ratio (porosity) in the heat-insulating layer occupied by pores having a pore diameter of 30 μm or less to be in the range of 45% to 65%, the above effects can be effectively exhibited. Investigated.

  In addition, when the fixing roller is a fixing roller in which an elastic body layer mainly composed of silicone rubber containing carbon fibers and having open-cell structure bubbles is formed on the surface of the core member, the above-described effect is further improved. I found out that it can be used effectively.

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

  FIG. 1 is a cross-sectional view showing a schematic configuration of a fixing device according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a part A in FIG. 3 is an enlarged cross-sectional view of a portion B in FIG. FIG. 4 is a cross-sectional view of an elastic layer in which conventional bubbles are not open-celled. FIG. 5 is a cross-sectional view of a core member used in the fixing roller shown in FIG. FIG. 6 is a cross-sectional view showing a modification of the circumferential protrusion of the core member shown in FIG. FIG. 7 is an enlarged cross-sectional view of a portion C in FIG.

  The fixing device according to this embodiment includes a fixing roller 1 that is a fixing rotating body, and a pressure roller 2 that is a pressing member that presses the fixing roller 1 by pressing a spring 4 or the like.

  As shown in FIG. 1, the fixing roller 1 has a rotation shaft (not shown), and has air bubbles 1 b 1 formed into a bubble on the surface of a metal hollow cylindrical core member 1 a having a heater 3 therein. It has a heat-resistant elastic layer 1b mainly composed of silicone rubber. Further, a release layer 1c made of a fluororesin such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) is formed on the surface of the elastic layer 1b. As shown in FIGS. 2 and 3, the elastic layer 1b contains bubbles 1b3 and carbon fibers 1b4 that are made open through the open bubbles 1b2. According to the fixing roller 1 of this embodiment having such a laminated structure, as shown in FIG. 2, heat from the heater 3 that is a heat source is transmitted to the core member 1a, and heat from the core member 1a is elastic layer 1b. Then, it is transmitted to the release layer 1c. Therefore, the release layer 1c can be brought into contact with the unfixed toner image T1 on the recording medium P to be heated and fixed to form a fixed toner image T2.

Here, FIG. 3 is an enlarged cross-sectional view in which the portion B of FIG. 2 is enlarged, and is a view showing the relationship between the open cell structure and the carbon fiber in the elastic layer 1b. Note that the open cell portion 1b2 refers to the bubble 1b3 that is connected to the adjacent bubble 1b3 ′, so that the gas in the bubble 1b3 can flow to the adjacent bubble 1b3 ′ during deformation.
On the other hand, FIG. 4 is an enlarged view showing an elastic body layer 10 containing a silicone rubber 10a and carbon fibers 10c having conventional single-bubble air bubbles 10b. As shown in FIG. 4, the elastic body layer 10 having a single-bubble structure is configured by including bubbles 10b and carbon fibers 10c having no continuous bubble portion in the silicone rubber 10a. Therefore, in such a conventional elastic body layer 10 having a single-bubble structure, gas cannot move between the pores, and the rigidity of the carbon fiber affects the characteristics of the silicone rubber and the durability is lowered. . On the other hand, the elastic layer 1b having the continuous bubble structure according to the present invention allows the bubbles 1b3 to be appropriately deformed when pressed by the pressure roller 2 during fixing, so that the bubble 1b3 can be appropriately deformed on the recording medium in the nip portion N. The toner image can be properly pinched and good durability can be exhibited.

  The above-mentioned fixing roller is manufactured by using a PFA tube 1c, which includes carbon fiber and pre-expanded particles, and further containing an unvulcanized addition type silicone rubber containing a curing agent, and an adhesive layer formed on the inner surface in advance, It inject | pours as an injection | pouring liquid between metal core members 1a (core metal) which provided convex part reinforcement (henceforth a rib). Next, the unvulcanized addition-type silicone rubber injected between the PFA tube 1c and the core member 1a is heated and bonded and fixed between the PFA tube 1c and the core member 1a to be elastic. The body layer 1b is formed. At this time, the foamed particles 1b3 mixed in the unvulcanized addition type silicone rubber are broken, and at the same time, the mold release agent volatilizes around the carbon fiber impregnated with the mold release agent to separate from the silicone rubber. Type. In this way, in order to effectively release the carbon fiber from the silicone rubber and form the open cell part 1b2, the carbon fiber is impregnated with a release agent such as glycerin, ethylene glycol, diethylene glycol, or triethylene glycol in advance. Use These mold release agents can volatilize around the carbon fiber by heat treatment during curing of the unvulcanized addition-type silicone rubber, and can appropriately form the open cell part 1b2.

  In the present embodiment, the elastic layer 1b is formed by injecting and solidifying an injection solution containing unvulcanized addition type silicone rubber between the PFA tube 1c and the core member 1a as described above. The silicone non-crosslinked liquid prepared in the same manner as the above injection solution is placed in a mold for forming the core member 1a in the elastic body layer, and injected between the mold and the core member to be placed on the surface of the core member 1a. An elastic body layer is formed with a predetermined thickness, and then a release layer 1c is formed by forming a coating layer of fluororesin such as PFA on the surface of the elastic body layer or covering with the above fluororesin tube. Anyway.

Here, as the fluororesin used, a resin having a good melt film-forming property by firing and a relatively low melting point (preferably 250 to 300 ° C.) is preferably selected. Specific examples include fine powders of low molecular weight polytetrafluoroethylene (PTFE), tetrafluoroethylene-hesafluoropropylene copolymer (FEP), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). .
Low molecular weight polytetrafluoroethylene (PTFE) powders are Lubron L-5, L-2 (above, Daikin Industries), MP1100, MP1200, MP1300, TLP-10F-1 (above, Mitsui DuPont Fluorochemical) It has been known. As the tetrafluoroethylene-hexafluoropropylene copolymer (FEP) powder, 532-8000 (manufactured by DuPont) is known. As the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), MP10, MP102 (manufactured by Mitsui DuPont FluoroChemica) are known. In particular, MP103, MP300 (above, Mitsui Dupont Fluoro Chemical Co., Ltd.), AC-5600, AC5539 (above, Daikin Industries Co., Ltd.) and the like are suitable for the present invention as those having a low MFR (melt flow rate) and low fluidity. ing.

  Further, the bubbles 1b2 in the elastic body layer 1b are obtained by adding a foaming agent, foamed particles or foamed particles to a composition of unvulcanized addition type silicone rubber containing carbon fiber and a curing agent. It can be formed by foaming of the foaming agent at the time of heat curing of the rubber or by the voids of the foamed particles or the already foamed particles. In this case, the foaming agent is azobisisobutyronitrile (AIBN) or the like, and the foamed particles are F-30, F-30VS, F-46, F-50D, F-55D manufactured by Matsumoto Yuka Pharmaceutical Co., Ltd. Etc. Examples of the already expanded particles include 100CA, 80CA, F-80ED, F-30E, F-50E, and F-80SDE manufactured by Matsumoto Yuka Pharmaceutical.

  Carbon fibers include PAN (polyacrylonitrile) based carbon fibers made from synthetic acrylic long fibers and pitch based carbon fibers made from coal tar and petroleum pitch. The PAN-based carbon fiber is obtained by carbonizing a PAN precursor (polyacrylonitrile fiber) and has properties of high strength and high elastic modulus. Pitch-based carbon fibers are obtained by carbonizing pitch precursors (pitch fibers obtained from coal tar or heavy petroleum oil as a raw material). Under various manufacturing conditions, low-modulus to ultra-high modulus / high strength A wide range of properties can be obtained. Ultra-high modulus products have excellent thermal conductivity and conductivity characteristics, as well as high rigidity applications. In the present invention, PAN-based and pitch-based carbon fibers can be used, but pitch-based carbon fibers having high thermal conductivity are preferable. As the pitch-based carbon fiber, Pitch-based Nippon Graphite Fiber Co., Ltd. product name: carbon fiber milled product number: XN-100-15M (150 microns), etc., having a high thermal conductivity of 500 W / mK is optimal. On the other hand, the thermal conductivity of polyacrylonitrile (PAN) -based carbon fiber is 50 W / mK at the maximum.

  Further, as the core member 1a of the fixing roller 1, as shown in FIG. 5, a metal roller-shaped core member (core metal) is used, and the thickness of the core metal 1a is 0.5 mm or less and 0.25 mm or more. In this case, it is preferable that a plurality of circumferential protrusions 1a1 are formed integrally with the roller cored bar 1a on the inner surface of the cored bar. By using such a cored bar, it is first the cored bar 1a that is heated from the heater 3 (see FIG. 1) disposed at the center of the roller cored bar 1a, so this heat capacity is also important. If the thickness is 0.5 mm or less, it is possible to start up for about several tens of seconds. However, since the strength against bending is reduced, a fixing device that can be quickly started up is configured in combination with one reinforced by the circumferential convex portion 1a1. Possible fixing rotation. In this case, a rib having a cross-sectional shape as shown in FIGS. 6B to 6D can be used as the circular protrusion 1a1. In addition, 1a2 in FIG. 5 shows a rotating shaft.

  In the above embodiment, the fixing roller 1 having the heater 3 incorporated in the core member 1a is used as the fixing rotating body having the heated elastic layer. However, as the fixing rotating body, the fixing roller 1 is provided in the core member 1a. A rotating roller that does not include the heater 3 but heats the elastic layer by bringing the heating roller including the heater into contact with the roller having the elastic layer, and a heating roller that includes the heater and a roller having the elastic layer The present invention can also be applied to a rotating body having a roller having an elastic layer heated by an endless heating belt and stretched by the heating belt.

  Next, a pressure roller according to an embodiment of the present invention will be described with reference to FIGS. A pressure roller 2 that is a pressure member according to the present embodiment includes a heat insulating layer mainly composed of a thermosetting resin such as an epoxy resin on the surface of a metal cylindrical core member 2a having rotating shafts 2a1 at both ends. 2d. More preferably, as shown in FIG. 1, a release layer 1c made of a fluororesin such as PFA is formed on the surface of the heat insulating layer 2d. As shown in FIG. 7, the heat insulating layer 2 d is formed with a large number of holes 2 d 2 having a hole diameter of 30 μm or less scattered in the thermosetting resin 2 d 1. Therefore, by dispersing the pores 2d2 having a pore diameter of 30 μm or less in the thermosetting resin 2d1 having a low thermal conductivity, the volume occupancy (porosity) of the pores 2d2 in the heat insulating layer can be easily set to about 50%. In addition, the heat insulating layer 2d having a low thermal conductivity of 0.1 W / mK or less can be easily obtained. As a result, the heat from the fixing roller 1 that is in pressure contact with the pressure roller 2 is prevented from being transferred to the core member 2a and dissipated, and the heat generated by the fixing roller 1 can be used effectively as the amount of heat for fixing. The rise time of the fixing device can be shortened.

  Such a good heat insulating property is thermosetting so that the pores 2d2 having a pore diameter of 30 μm or less, preferably 20 μm to 30 μm in the thermosetting resin 2d1 have a porosity of 45% to 65%. It is sufficient if it is mixed in the resin. In addition, the heat insulating layer 2d mainly composed of a thermosetting resin having such a hole diameter and porosity is harder than the elastic body layer 1b of the fixing roller 1 described above, and is almost in contact with the fixing roller 1. A good smooth outer peripheral surface shape can be maintained without being deformed. Therefore, as shown in FIG. 1, the elastic deformation along the surface shape of the recording medium P at the nip portion N of the fixing roller 1 having the heated elastic layer 1b is appropriately performed, so that The gloss of the toner image can be improved and the occurrence of uneven gloss can be suppressed.

  As the thermosetting resin that constitutes such a hard heat insulating layer 2d, a thermosetting resin that is hardly changed by heating from the heated fixing roller 1 is used, and preferably has a heat resistance of 100 ° C. or higher. A thermosetting resin is desirable, and a thermosetting epoxy resin is preferable.

  Further, in order to form pores having the above-mentioned pore diameter in the heat insulating layer with a predetermined porosity, it can be appropriately achieved by mixing the above-mentioned foaming agent, foamed particles, and already foamed particles in the thermosetting resin. In particular, the use of already-expanded particles is preferable because the pore diameter and the porosity can be easily controlled.

  In the case of forming a heat insulating layer having pores having the above pore diameter and porosity, for example, an epoxy mixture in which foamed particles and an uncured epoxy resin are mixed, and further, an epoxy resin curing agent and a curing accelerator are mixed. To prepare. Subsequently, the PFA tube 2c having an adhesive layer formed on the inner surface in advance and the metal core member 2a are set so as to have a predetermined interval, and the epoxy mixture is placed in the interval between the PFA tube 2c and the core member 2a. Inject as an infusion. In this state, the epoxy resin is heated to cure the epoxy resin (primary heating). Next, heating (secondary heating) is performed at a temperature higher than the primary heating, and the heat insulating layer 2d is bonded to the PFA tube 2c and the core member 2a and fixed integrally. As described above, by performing the primary heating and the secondary heating, the already foamed particles mixed with the uncured epoxy resin are broken, and voids are generated in the epoxy resin. The pressure roller provided with the heat insulating layer 2d having can be reliably manufactured.

  In the above embodiment, a gap is formed between the PFA tube 2c and the core member 2a, and the epoxy mixture is injected into the gap to form a heat insulating layer. A core member is placed in the mold, the epoxy mixture is cast between the mold and the core member, and primary heat and secondary heat are formed to form the heat insulating layer 2d on the core member 2a. Furthermore, it can also be produced by forming a release layer 2c by forming a coating layer of a fluorine resin on the surface of the heat insulating layer 2d thus molded, or by covering with a fluorine resin tube. .

  As described above, in the fixing device according to the present embodiment, by using the fixing roller 1 having the above-described laminated structure, the heat from the heater 3 as a heat source is transmitted to the core member 1a as shown in FIG. The heat from the core member 1a is transmitted to the release layer 1c through the elastic body layer 1b. Therefore, the release layer 1c can be brought into contact with the unfixed toner image T1 on the recording medium P to be heated and fixed to form a fixed toner image T2. In addition, in this case, since the heat insulating property of the pressure roller 2 is very high as described above, the start-up of the fixing device can be accelerated. Further, since the hard heat insulating pressure roller 2 and the fixing roller 1 using a high heat conductivity and low specific heat material are used, the recording medium P at the exit of the nip portion N is along the outer peripheral surface of the pressure roller 2. Therefore, it is possible to suppress the occurrence of a conveyance jam due to winding around the outer peripheral surface of the fixing roller 1 being conveyed and heated.

  In the above embodiment, the pressure roller is exemplified as the pressure member. However, the pressure member may be an endless pressure belt stretched around a plurality of rollers.

  Next, an image forming apparatus including the fixing device will be described with reference to FIG. FIG. 8 is a cross-sectional view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

  The image forming apparatus 100 according to this embodiment includes a charger 102, a writing device 103, a developing device 104, a transfer device 105, and a cleaning device 106 around a drum-shaped photoconductor 101. The surface of the photoconductor 101 is uniformly charged, for example, to the positive electrode by the charger 102, and the optical information L based on the image information is applied to the surface of the photoconductor 101 uniformly charged in this way by the writing device 103. Irradiation forms an electrostatic latent image on the surface of the photoreceptor 101. Next, the electrostatic latent image formed on the photosensitive member 101 is supplied with the agitated and charged toner T from the developing device 104, and the electrostatic latent image becomes a toner image. The image is transferred to the recording medium P by the device 105. The unfixed toner T1 on the transferred recording medium P carries the unfixed toner T1 at the nip portion N between the fixing roller 1 and the pressure roller 2 in the fixing device 107 as shown in FIG. By transporting the recording medium P, the unfixed toner T1 is fixed to the recording medium P.

  As described above, the toner image T2 fixed in this manner has gloss and uneven glossiness by the fixing roller 1 having the heated elastic layer 1b and the pressure roller 2 having the hard heat insulating layer 2d. It will be suppressed.

  Next, the present invention will be specifically described based on examples and comparative examples.

(Production of pressure roller)
[Test 1]
To 100 parts by mass of jER8282 (uncured epoxy resin) manufactured by Japan Epoxy Resin Co., Ltd., Expandel 461DE (foamed particles, approximate diameter: 20 μm) manufactured by Nippon Philite Co., Ltd., porosity 40% (Comparative Example 1), 45 % (Example 1), 50% (Example 2), 65% (Example 3), 70% (Comparative Example 2), and 75% (Comparative Example 3) And 86 parts by mass of acid anhydride MHAC-P (curing agent) manufactured by Hitachi Chemical Co., Ltd. and 1 part by mass of imidazole 2E4MZ (curing accelerator) manufactured by Shikoku Kasei Co., Ltd. were mixed. Mixing was performed using a Mazerustar manufactured by Kurashiki Boseki. The mixture was poured into a casting mold in which the core member of the pressure roller was placed in the mold of the pressure roller, and heated at 100 ° C. for 2 hours and 30 minutes to perform a primary heat treatment.
Next, secondary baking was performed at 250 ° C. for 8 hours to form a heat insulating layer, and a 30 μm PFA tube was bonded onto the heat insulating layer to form a pressure roller. In this case, the outer diameter of the pressure roller was Φ40 mm, and the thickness of the heat insulating layer was 3 mm.

(Fixing roller production)
Next, the fixing roller will be described. In addition type liquid silicone containing a curing agent, F-80ED manufactured by Matsumoto Yushi Seiyaku Co., Ltd. (pre-expanded particles, approximate diameter: 100 μm) and XN-100-15M manufactured by Nippon Graphite Fiber Co., Ltd. (pitch system having a length of 150 μm) Carbon fiber powder is dispersed. As XN-100-15M, one previously mixed with glycerin in an amount of 1/8 by mass ratio was used. Mixing was performed using a Mazerustar manufactured by Kurashiki Boseki. This unvulcanized addition type silicone rubber is set with a core metal 1a (refer to FIG. 5) in which a PFA tube having an adhesive layer formed on the inner surface in advance and a 0.5 mm thick convex portion reinforcement (referred to as a rib) is provided on the inner side. In the meantime, it is injected between the PFA tube and the metal core as an injection solution. At this time, primary heating was performed by heating at 120 ° C., and then secondary heating was performed by heating at 200 ° C. for 4 hours. At this time, the foamed particles were broken, and the periphery of the carbon fiber was released from the silicone rubber, and the bubbles were connected to each other. In a series of steps, a fixing roller having an outer diameter of Φ40 mm and an elastic layer thickness of 3 mm was produced.

[Test 2]
In the same manner as in Test 1, in the production of the pressure roller, instead of Expandel 461DE (pre-expanded particles, approximate diameter: 20 μm) of the heat-insulating layer composition in Test 1, Matsumoto Yushi Seiyaku F80SDE (existing) Using expanded particles, approximate diameter: 30 μm) porosity 40% (Comparative Example 4), 45% (Example 4), 50% (Example 5), 65% (Example 6), 70% ( Comparative Example 5), a pressure roller was prepared as a mixture with a heat insulating layer blending amount of 75% (Comparative Example 6).

[Test 3]
In the same manner as in Test 1, in the production of the pressure roller, instead of Expandel 461DE (pre-expanded particles, approximate diameter: 20 μm) of the heat insulating layer blend composition in Test 1, Matsumoto Yushi Seiyaku F80DE (existing) Using expanded particles, approximate diameter: 100 μm), porosity 40% (Comparative Example 7), 45% (Comparative Example 8), 50% (Comparative Example 9), 65% (Comparative Example 10), 70% ( Comparative Example 11), a pressure roller was prepared as a mixture of the heat insulating layer blending amount of 75% (Comparative Example 12).

  These were set in a fixing unit of a copying machine (MF4570) manufactured by Ricoh, and the temperature rise time (seconds) up to 160 ° C. was measured with a 1000 W halogen heater. In this case, the pressure roller used in each of the examples and comparative examples was used. The temperature was measured by providing a thermocouple in the upper part of the fixing roller. The porosity of the elastic layer on the fixing roller side was 50%.

  The approximate diameter of the already-expanded particles is the central value of the average particle diameter of the used already-expanded particles. The ones used this time are F80DE (average particle size: 90 to 110 μm) of Matsumoto Yushi Seiyaku: center value 100 μm, F80SDE (average particle size: 20 to 40 μm) of Matsumoto Yushi Seiyaku Co., Ltd. Pancell 461DE (average particle size: 15 to 25 μm): center value is 20 μm.

(Durability evaluation)
An acceleration test was conducted as a confirmation of durability. As an acceleration test, a hollow heating roller having an outer diameter of Φ40 mm and a thickness of 1 mm (corresponding to a fixing rotator) was applied with a force of 50 N on the pressure roller, and a halogen heater was provided in the hollow roller, and 200 ° C. The time when surface depression occurred was measured. Although not shown, the apparatus is provided with a pressure mechanism on the pressure roller side, the axial position of the heating roller is fixed, and the position in the direction in which the left and right end positions of the pressure roller are pressed is measured by a laser length measuring device. The end point time was defined as the time when either of them varied by 100 μm. In this apparatus, since the nip portion can hardly be formed, the pressure becomes about one digit larger than the normal nip pressure (10 N / cm ² ). This measurement was performed for 240 hours. Those that did not change up to this point were marked as ○.

(Glossiness evaluation)
Next, as an evaluation of gloss unevenness, a magenta solid unfixed toner image of 20 mm × 20 mm IMAGIO MP C4500 made by Ricoh Co., Ltd. was prepared on a Ricoh company (Type 62000, A4 transfer paper) as a recording medium. This solid image of 20 mm × 20 mm was created on the whole A4 at intervals of 20 mm before and after. This paper was passed through the fixing unit of MF4570 and measured at 60 ° with a gloss meter GM-60 manufactured by Konica Minolta (full width). The fixing temperature setting is 160 ° C. The glossiness unevenness is a value obtained by subtracting the minimum value from the maximum value of 8 points that have passed through the nip portion N at the same time.

  Tables 1 to 3 show the evaluation results of [Test 1], [Test 2], and [Test 3].

  As is apparent from the results of Table 1 above, in the case of Comparative Example 1, the porosity is as low as 40%, so the temperature rise time is as long as 28 seconds, and the porosity shown in Comparative Example 2 is 70%. If it is as high as%, the durability is poor at 104 hours in the accelerated test. Further, in the case where the fixing roller having the single bubble structure shown in Comparative Example 3 is used, the accelerated test is 52 hours and the durability is further deteriorated as compared with that in Comparative Example 2.

  On the other hand, in Examples 1 to 3 according to the present invention, 20 μm of already expanded particles are used and the porosity is in the range of 45% to 65%. Good durability of 240 hours or more. Moreover, it is apparent that the glossiness is improved as compared with that of Comparative Example 1 and the glossiness unevenness is reduced.

  Moreover, in the result of the said Table 2, even when the diameter of the already-expanded particle | grains was 30 micrometers, in Comparative Examples 4-6, like Comparative Examples 1-3, start-up time becomes long, or durability. Is bad. However, by setting the porosity to 45% to 65% (Example 4 to Example 6), as in the case of Example 1 to Example 3, early start-up, good durability, and good gloss It is clear that the brightness and low gloss unevenness are shown.

  In addition, as shown in Table 3 above, even when the porosity is 45% to 65% (Comparative Example 8 to Comparative Example 10), 100 μm of foamed particles are used, so the durability in the acceleration test is poor and the glossiness is low. It is clear that unevenness is likely to occur.

[Test 4]
In order to verify the durability test, a fixing tester using the fixing unit of the copying machine of MF4570 (a copying machine manufactured by Ricoh) using the pressure roller of Example 2 and Comparative Example 2 described above was manufactured, and Ricoh Company An unfixed image of imgio MP C4500 manufactured by Imagio was passed through. In Example 2, there was no problem even with 50000 sheets. However, in Comparative Example 2, 7650 sheets were cracked on the surface, and the state was transferred to the image.

[Test 5]
The epoxy resin was cured at 100 ° C., 150 ° C., 200 ° C., and 250 ° C. for 8 hours at a time when the heat insulating layer of the pressure roller of Example 2 was produced. In this case, instead of the heat insulating layer of the pressure roller, a sample having a thickness of 2 mm and a size of 100 mm × 100 mm was prepared, and the porosity of this sample was determined. As a result, in the order of the treatment temperature, the porosity decreased as the foamed particles were broken down to 50%, 45%, 20%, and 10%. In addition, observation with an optical microscope revealed that the foamed particles were broken and larger pores were observed.

  Moreover, about the hardening process of the sample of the epoxy resin at the time of preparation of the heat insulation layer of the pressure roller of Example 2, when the acceleration test is performed only at the primary baking at 100 ° C., the end time is about 24 hours, and the durability is increased. Turned out to be lower.

1 Fixing roller 1a Core member (core metal)
DESCRIPTION OF SYMBOLS 1b Elastic body layer 1b1 Hole 1b2 Opening part 1b3 Bubble 1b4 Carbon fiber 1c Release layer 2 Pressure roller 2a Core member 2c Release layer 2d Heat insulation layer 2d1 Epoxy resin 2d2 Hole 3 Heater 4 Spring 101 Photoconductor 102 Charger DESCRIPTION OF SYMBOLS 103 Writing device 104 Developing device 105 Transfer device 106 Cleaning device 107 Fixing device

JP 2006-285006 A

Claims (9)

A pressurizing member that presses a recording medium having an unfixed toner image on a surface thereof against a fixing rotator having an elastic layer to fix the unfixed toner image on the recording medium;
The pressure member has a heat insulating layer mainly composed of a thermosetting resin having pores having a pore diameter of 30 μm or less on a substrate and having a porosity of 45 to 65%. A pressure member formed. The pressure member according to claim 1,
The pressurizing member, wherein the pores are formed by already expanded particles.   3. The pressure member according to claim 1, wherein the base material is a core member that has a rotation shaft and is rotatable. The pressurizing member according to any one of claims 1 to 3,
A pressurizing member comprising a release layer containing a fluororesin on a surface in contact with the recording medium.   A coating layer containing the foamed particles in an uncured resin is provided on a substrate, the coating layer is heated at a predetermined temperature to primarily cure the uncured resin, and then heated at a temperature higher than the predetermined temperature. Then, the pressure member according to any one of claims 1 to 3, wherein the pressure member according to any one of claims 1 to 3 is formed by performing secondary curing to form a heat insulating layer.   A coating layer containing the foamed particles in an uncured resin is provided on a substrate, the coating layer is heated at a predetermined temperature to primarily cure the uncured resin, and then heated at a temperature higher than the predetermined temperature. Then, secondary curing is performed to form a heat insulating layer, and a release layer containing a fluororesin is further adhered onto the heat insulating layer to obtain the pressure member according to claim 4. Pressure member manufacturing method. A fixing rotator to be heated; and a pressure member that presses a recording medium having an unfixed toner image on the surface thereof against the fixing rotator to fix the unfixed toner image on the recording medium. In the fixing device,
The fixing device according to claim 1, wherein the pressure member is the pressure member according to claim 1. The fixing device according to claim 7.
The fixing rotator is a fixing rotator in which an elastic layer mainly composed of carbon fiber and silicone rubber containing bubbles having an open cell structure is formed on the surface of a core member having a rotating shaft. Fixing device to do. An image carrier that forms an electrostatic latent image on the surface, a developing device that supplies toner to the electrostatic latent image on the surface of the image carrier and converts the electrostatic latent image into a toner image; An image provided with a transfer device for transferring a toner image to the surface of a recording medium, and a fixing device for fixing the toner image on the surface of the recording medium by heating and pressurizing the toner image transferred to the surface of the recording medium by the transfer device In the forming device,
9. The image forming apparatus according to claim 7, wherein the fixing device is a fixing device according to claim 7 or 8.

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