JP2011033653A - Image heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a reduction of a fluorine-series oil in a heat-resistant lubricant due to an operation, and thereby a normal friction state between a heater member and a belt member with the heat-resistant lubricant interposed therebetween can be maintained for a long time. <P>SOLUTION: When a pressing roller 45 rotates in abutment with the outside surface of the fixing belt 43, the heater 41 heats the fixing belt 43 while rubbing the inside surface of the fixing belt 43 with the ceramic structure surface thereof. A nip formation member 42 with the heater 41 fixed thereto is biased by a biasing member 52 toward the pressing roller 45, and thereby the fixing belt 43 is sandwiched between the heater 41 and the pressing roller 45. A silicon-series oil is applied to the ceramic structure surface as the rubbing surface of the heater 41, and thereby to make to be hard to come into contact with a grease-like fluorine-series lubricant applied to the inside surface of the fixing belt 43. Accordingly, the deterioration speed of the fluorine-series lubricant becomes low, and the squeal phenomenon of the fixing belt 43 is made to be hard to occur. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image heating apparatus for performing heat and pressure processing of a recording material carrying a toner image using a belt member having an inner surface coated with a lubricant, and more specifically, a heater member and a belt via a heat-resistant lubricant The present invention relates to a structure that lasts a normal friction state of a member.

  2. Description of the Related Art Image forming apparatuses that transfer a toner image onto a recording material and then fix the full-color or black-and-white image on the recording material by heating while nipping and conveying the recording material in a heating nip of an image heating apparatus are widely used. Here, the image heating apparatus reheats the recording material carrying the semi-fixed or fixed image in addition to the fixing device that fixes the unfixed toner image on the recording material, and adjusts the finish of the image surface. Also includes devices.

  A quick start type (or on-demand type) image heating apparatus that rises quickly at start-up has been put into practical use. Patent Document 1 discloses a film heating type fixing device that forms a heating nip of a recording material by pressing a driving roller against an outer surface of a film-like belt member that rotates by sliding on a heater member fixed to a support member. Indicated. The quick start method has less heat capacity of the belt member, so the temperature of the heating nip rises faster and there is no need to supply power during standby, so the overall power consumption is lower compared to the conventional roller heating method. That's it.

  In Patent Document 1, a heater member in which a heater pattern is formed on the back surface of a thin aluminum nitride substrate having good thermal conductivity is used, and the front surface of the substrate, that is, the friction surface with the belt member is coated with glass. Yes.

  Patent Document 2 discloses a method for manufacturing a heater member in which a heater pattern is formed on the back surface of a thin plate-like ceramic substrate. Here, the rubbing surface of the aluminum nitride substrate with respect to the belt member is covered with the resin coat layer.

  In Patent Document 3, a grease-like heat-resistant lubricant containing fluorine-based fine particles and fluorine-based oil is applied to the inner surface of the belt member in order to reduce the frictional load caused by sliding with the heater member as the belt member rotates. Application is shown.

JP 2000-29334 A JP 2006-331950 A JP 2000-338801 A

  As shown in Patent Documents 1 and 2, by using a ceramic material with good thermal conductivity, a heater with a quick rise in the temperature of the friction surface against the belt member even when the heater pattern is arranged on the back side of the ceramic substrate. A member is obtained. Even if the temperature sensor is arranged on the back side of the ceramic substrate, the temperature change of the belt member can be detected quickly. For this reason, it is possible to quickly adjust the heater input power with respect to the temperature change of the belt member, and to perform precise temperature control with a small fluctuation in the temperature of the fixing nip.

  In this respect, the glass coating layer (Patent Document 1) and the resin coating layer (Patent Document 2) covering the rubbing surface have lower thermal conductivity than the ceramic substrate and increase the thickness of the heater member. The responsiveness of temperature adjustment is impaired.

  Therefore, it has been proposed to directly rub the ceramic structure surface on which the glass coating layer and the resin coating layer are not formed with respect to the belt member. In this case, since the aluminum nitride substrate itself has a high friction coefficient and is very hard, as shown in Patent Document 3, a heat-resistant lubricant is applied to the inner surface of the belt member, and the heat-resistant lubricant layer is interposed therebetween. It is necessary to slide the ceramic structure surface against the belt member.

  However, when such an experiment was actually conducted, it was found that the normal friction state between the heater member and the belt member via the heat-resistant lubricant could not be maintained at an extremely early stage compared to the assumed design life. did. Despite the presence of heat-resistant lubricant, the friction between the heater member and the belt member increases, causing vibration and noise (squeal) during operation, and responding to vibration in the fixed image Uneven gloss occurred.

  Therefore, when such an abnormality occurred, the heat-resistant lubricant was sampled from between the heater member and the belt member and analyzed, and the ratio of fluorine-based oil in the heat-resistant lubricant decreased and the ratio of fluorine-based fine particles. Has been confirmed to be increasing. In other words, it was confirmed that the lubrication performance of the heat-resistant lubricant was reduced by increasing the proportion of fluorine-based fine particles added to increase the consistency of the heat-resistant lubricant and impart grease-like properties. It was done.

  The present invention provides an image heating apparatus capable of suppressing a decrease in fluorine-based oil in a heat-resistant lubricant during operation and prolonging a normal friction state between a heater member and a belt member via the heat-resistant lubricant. It is intended to provide.

  The image heating apparatus according to the present invention includes a belt member, a driving member that contacts the outer surface of the belt member to rotate the belt member, and the belt member while sliding a ceramic structure surface against the inner surface of the belt member. A heater member that heats the heater member, a support member that is disposed along the longitudinal direction of the heater member and supports the heater member, and urges the support member toward the drive member, and the heater member and the drive member And an urging mechanism for sandwiching the belt member therebetween, and a grease-like heat-resistant lubricant containing fluorine oil is interposed between the heater member and the belt member. A liquid that is non-volatile at the operating temperature and immiscible with the fluorinated oil covers the ceramic structure surface.

  In the image heating apparatus of the present invention, since the ceramic structure surface of the heater member is covered with a non-volatile liquid that is immiscible with the fluorinated oil, the fluorinated oil contained in the heat-resistant lubricant is the heater member. It is difficult to contact the ceramic structure surface. For this reason, decomposition | disassembly of the fluorine-type oil which generate | occur | produces in the ceramic structure surface heated at high temperature is suppressed, and the ratio of the fluorine-type oil which occupies for a heat resistant lubricant does not fall easily.

  Accordingly, it is possible to suppress a decrease in the fluorine-based oil in the heat-resistant lubricant accompanying the operation, and to maintain a normal friction state between the heater member and the belt member via the heat-resistant lubricant.

1 is an explanatory diagram of a configuration of an image forming apparatus. FIG. 3 is an explanatory diagram of a configuration of a fixing device. FIG. 6 is an explanatory diagram of control of the fixing device. It is explanatory drawing of the structure of a heater. FIG. 6 is an explanatory diagram of a state of an interface between a fixing belt and a heater. FIG. 10 is an explanatory diagram of a method for assembling the fixing belt assembly. It is explanatory drawing of the application effect of silicone type oil. It is explanatory drawing of the experimental result of the noise of a fixing belt.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present invention, as long as a liquid immiscible with the fluorinated oil is detected on the rubbing surface of the heater member, a part or all of the configuration of the embodiment is replaced with the alternative configuration. It can also be implemented in the embodiment.

  Therefore, the image heating apparatus is not limited to the image heating apparatus in which the pressure roller is pressed against the belt member, and the image heating apparatus can be implemented in which the pressure belt is pressed against the belt member.

  An image forming apparatus equipped with an image heating apparatus can be implemented without distinction between an intermediate transfer belt system, a recording material conveyance belt system, a system that transfers a toner image to a recording material, a tandem type, and a drum type. In the present embodiment, only main parts related to toner image formation / transfer will be described. However, in addition to necessary equipment, equipment, and a housing structure, various printers, various printing machines, copiers, fax machines, multifunction machines, etc. Can be implemented in

  In addition, about the general matter of the image heating apparatus shown by patent documents 1-3, illustration is abbreviate | omitted and the overlapping description is abbreviate | omitted.

<Image forming apparatus>
FIG. 1 is an explanatory diagram of the configuration of the image forming apparatus. As shown in FIG. 1, the image forming apparatus 10 is a tandem type full-color printer in which image forming units 10Y, 10M, 10C, and 10K are arranged along an intermediate transfer belt 31.

  In the image forming unit 10 </ b> Y, a yellow toner image is formed on the photosensitive drum 11 </ b> Y and is primarily transferred to the intermediate transfer belt 31. In the image forming unit 10M, a magenta toner image is formed on the photosensitive drum 11M, and is primarily transferred onto the yellow toner image on the intermediate transfer belt 31. In the image forming units 10C and 10K, a cyan toner image and a black toner image are formed on the photosensitive drums 11C and 11K, respectively, and similarly, the toner images on the intermediate transfer belt 31 are sequentially superimposed and sequentially transferred.

  The four color toner images carried on the intermediate transfer belt 31 are collectively secondary transferred onto the recording material P by the secondary transfer portion T2. The recording material P drawn from the recording material cassette 20 by the pickup roller 21 and separated one by one by the separation roller waits at the registration roller 23, and performs secondary transfer in synchronization with the toner image on the intermediate transfer belt 31. Sent to the part T2.

  The recording material P onto which the toner image has been secondarily transferred at the secondary transfer portion T2 is heated and pressurized by the fixing device 40 and fixed on the surface, and then discharged onto the discharge tray 64 through the discharge roller 63. The

  When images are formed on both sides of the recording material P, the recording material P on which the toner image is fixed by the fixing device 40 is guided upward by the flapper 61, and when the rear end reaches the reversal point R, the switchback conveyance is performed. Is reversed. Thereafter, the recording material P is conveyed on the double-sided conveyance path 70 and stands by the registration roller 23, and the toner image is transferred and fixed on the back side by the above procedure, and the other side is subjected to the same process as the one-sided image formation. A toner image is formed and discharged to the discharge tray 64.

  The image forming units 10Y, 10M, 10C, and 10K are configured substantially the same except that the color of the toner used in the developing device attached thereto is different from yellow, magenta, cyan, and black. Hereinafter, the image forming unit 10Y will be described, and the other image forming units 10M, 10C, and 10K will be described by replacing “Y” at the end of the reference code with “M”, “C”, and “K”.

  In the image forming unit 10Y, a corona charger 12Y, an exposure device 13Y, a developing device 14Y, a transfer blade 17Y, and a cleaning device 15Y are arranged around the photosensitive drum 11Y. The photosensitive drum 11Y is composed of a metal cylinder on which a negatively charged photosensitive layer is formed, and rotates in a direction indicated by an arrow at a predetermined process speed.

  The corona charger 12Y charges the surface of the photosensitive drum 11Y to a uniform negative potential. The exposure device 13Y writes an electrostatic image of the image on the surface of the charged photosensitive drum 11Y. The developing device 14Y stirs and charges the two-component developer, and reversely develops the electrostatic image on the photosensitive drum 11Y with the negatively charged toner.

  The transfer blade 17Y presses the inner surface of the intermediate transfer belt 31 to form a primary transfer portion between the photosensitive drum 11Y and the intermediate transfer belt 31. By applying a positive DC voltage to the transfer blade 17Y, the toner image carried on the photosensitive drum 11Y is primarily transferred to the intermediate transfer belt 31.

  The secondary transfer roller 35 sandwiches the intermediate transfer belt 31 between the counter roller 34 and forms a secondary transfer portion T <b> 2 between the intermediate transfer belt 31 and the secondary transfer roller 35. The secondary transfer unit T2 overlaps and conveys the recording material P on the intermediate transfer belt 31 carrying the toner image, and applies a positive direct current voltage to the secondary transfer roller 35, so that the intermediate transfer belt 31 The toner image is secondarily transferred to the recording material P.

<Fixing device>
FIG. 2 is an explanatory diagram of the configuration of the fixing device. FIG. 3 is an explanatory diagram of the control of the fixing device. FIG. 4 is an explanatory diagram of the structure of the heater.

  As shown in FIG. 2, the fixing device 40 is a heating device of a film heating method of a pressure rotator driving method. The heater 41 is a ceramic heater as a heating member. The nip forming member 42 fixedly supports the heater 41, and is formed of a heat-resistant resin material such as a liquid crystal polymer having a substantially arc shape in cross section and having a longitudinal direction as a longitudinal direction in the drawing. The nip forming member 42 is also a rotation guide member for the cylindrical fixing belt 43.

  The heater 41 is disposed by being fitted with a ceramic structure surface exposed downward in a groove 42a formed along the length of the lower surface of the nip forming member 42, and fixed by a heat resistant adhesive or the like.

  The fixing belt 43 is a cylindrical (endless) heat-resistant belt member as a belt member that transmits heat, and is loosely fitted to the nip forming member 42 to which the heater 41 is fixed. The fixing belt 43 is preferably as thin as possible in order to reduce the heat capacity and improve the quick start performance. For example, the inner surface of a metal base material such as SUS or Ni of 50 μm or less and 20 μm or more is coated with 5 to 30 μm of PI, PTFE, PFA, FEP, etc., while the outer surface is provided with a silicon rubber layer and a fluorine rubber layer as an elastic layer It is formed into a composite layer structure. Further, a fluororesin layer as a toner release layer, specifically, a PFA tube layer, a PTFE coating layer, or the like may be provided on the outermost layer.

  Here, a silicon rubber layer of 300 μm on a metal substrate having a thickness of 40 μm, a PFA tube layer of 30 μm on the outermost layer, an inner surface of the metal substrate to improve the slidability of the heater, and prevent wear of the metal substrate. A fixing belt having an inner diameter of 30 mm provided with a 10 μm PI layer is used.

  The stay 44 is a beam-like pressure member disposed inside the nip forming member 42, and supports the entire length of the nip forming member 42 in the longitudinal direction to suppress bending. As the material of the stay 44, SUS, iron, or the like that can provide the necessary strength as a double-supported beam can be used. In this embodiment, SUS having a thickness of 3.0 mm is used.

  The pressure roller 45 is a roller member formed of a heat-resistant elastic material as a driving member, and is formed of a heat-resistant rubber such as silicon rubber or fluorine rubber or a foam of heat-resistant rubber on the outer peripheral surface of the cored bar 45a. The elastic layer 45b is disposed.

  In this embodiment, an elastic layer 45b made of silicon rubber having a thickness of 3.5 mm is provided on the outer periphery of an iron cored bar 45a having a diameter of 11.5 mm, and a release layer 45c made of a PFA tube having a thickness of 50 μm is provided on the outermost layer. ing.

  As shown in FIG. 3, the heater 41, the nip forming member 42, the fixing belt 43, and the stay 44 are assembled to the fixing belt assembly TA with the mutual positional relationship fixed by flanges 51 arranged at both ends in the longitudinal direction. ing. The fixing belt assembly TA holds the fixing belt 43 loosely on the outer periphery of the pressure unit KU in which the heater 41, the nip forming member 42, and the stay 44 are assembled by the flange 51. While both ends of the fixing belt 43 are restrained from moving in the longitudinal direction by the flange 51, the rotation direction is rotatable by rubbing both ends against the flange 51.

  The fixing belt assembly TA is arranged in parallel to the pressure roller 45 with the heater 41 side facing downward. The urging member 52 presses both ends of the stay 44 downward, the lower surface of the heater 41 is opposed to the upper surface of the pressure roller 45 via the fixing belt 43, and resists the elasticity of the elastic layer 45b of the pressure roller 45. Press. As a result, a fixing nip (N: FIG. 2) having a predetermined width is formed as a heating portion for the recording material carrying the toner image.

  Both ends of the pressure roller 45 are rotatably supported by bearings 53, while the fixing belt assembly TA is rotatably supported by the fixing belt 43 around the central pressure unit KU. The pressure roller 45 is rotationally driven at a predetermined rotational peripheral speed by a motor 54b controlled by the control unit 50 via a gear 54a attached to an end portion. A rotational force acts on the cylindrical fixing belt 43 due to a pressure frictional force at the fixing nip between the pressure roller 45 and the fixing film 43 by the rotational driving of the pressure roller 45. As a result, the fixing belt 43 is driven to rotate along the nip forming member 42 while closely sliding on the downward surface of the heater 41.

  That is, in the image heating device (40), when the drive member (45) rotates in contact with the outer surface of the belt member (43), the heater member (41) slides the ceramic structure surface against the inner surface of the belt member. The belt member is heated while allowing the belt member to heat. At this time, the support member (42) supports the opposite surface of the heater member (41) that is rubbed against the belt member (43). The urging mechanism (52) urges the support member (42) toward the drive member (45) to sandwich the belt member (43) between the heater member (41) and the drive member (45).

  As shown in FIG. 4A, the heater 41 is a heating member having a low heat capacity in which heating resistor layers 413a and 413b are formed on the substrate surface of an elongated thin plate-like ceramic substrate 411. For this reason, the heater 41 rises in temperature with a steep rising characteristic in the entire longitudinal direction by energization of the heating resistor layers 413a and 413b.

  In this embodiment, two heating resistance layers 413a and 413b are formed on a ceramic substrate 411 having a thickness of 600 μm so that the temperature distribution in the longitudinal direction can be adjusted. Thus, a uniform heating length of 324 mm is achieved. Secured.

  As shown in FIG. 4B, the sliding surface of the heater 41 is a ceramic structure surface of aluminum nitride (AlN).

As shown in FIG. 4C, the heating resistor layers 413a and 413b are covered with a glass protective layer 414 having a thickness of 80 μm. The heat generating resistor layers 413a and 413b are formed in a thin band shape by screen printing of a paste prepared by kneading silver, palladium, glass powder (inorganic binder), and organic binder. As a material for the heating resistor layers 413a and 413b, an electric resistance material such as RuO ₂ or Ta ₂ N may be used in addition to silver palladium (Ag / Pd).

  As shown in FIG. 3, the temperature adjustment circuit 55 controls power supply from the power source 57 to the heater 41 so that the temperature detected by the thermistor 56 provided on the back surface of the heater 41 converges to a predetermined temperature. The control unit 50 sets a temperature adjustment target temperature in the temperature adjustment circuit 55, and starts / stops power supply to the heater 41 in accordance with the start-up / operation status of the image forming apparatus (100: FIG. 1).

  Since the heater 41 does not cover the ceramic structure surface with high thermal conductivity with glass or resin with low thermal conductivity, the heat generated by the heating resistor layers 413a and 413b is quickly transmitted to the fixing belt 43. Further, the thermistor 56 quickly detects the temperature drop of the fixing belt 43 due to the passage of the recording material. Therefore, it is possible to quickly adjust the heat generation amount of the heating resistor layers 413a and 413b following the temperature change of the fixing belt 43, and to keep the temperature fluctuation of the fixing nip small.

<Heat resistant lubricant>
As shown in FIG. 2, the fixing device 40 is pressed against the fixing belt 43 in the fixing nip N in a state in which the heater 41 is energized and the heater 41 quickly rises in temperature and rises to a predetermined temperature. A recording material P carrying an unfixed toner image t is introduced between the roller 45 and the roller 45. In the fixing nip N, the image surface of the recording material P is brought into close contact with the outer surface of the fixing belt 43, and the fixing nip N is nipped and conveyed together with the fixing belt 43. In this nipping and conveying process, the unfixed toner image t is heated and pressurized on the recording material P by the heat of the fixing belt 43 heated by the heater 41 and melted and fixed. The recording material P that has passed through the fixing nip N is discharged after being separated from the surface of the fixing belt 43 by curvature.

  Since the fixing device 40 employs a film heating method (on-demand method) that heats the image surface of the recording material P via a fixing belt 43 having a small heat capacity, the heat transfer efficiency is high and the fixing temperature rises quickly. . The fixing device 40 sandwiches and conveys the recording material P between the fixing belt 43 heated by the heater 41 supported by the stay 44 and the pressure roller 45 to heat and fix the unfixed toner image t to the recording material P. Let

  For this reason, the fixing nip N of the fixing device 40 is pressurized with a force of a certain level or more from the viewpoint of fixing property and offset property (release property), and is heated to a high temperature. For this reason, if the heater 41 and the fixing belt 43 are directly rubbed, sticking development may occur in the fixing nip. When the sticking development occurs, the fixing belt 43 is in a so-called stick-and-slip state, causing frictional fluctuations in the audible sound range, and abnormal noise is generated from the fixing nip. Further, when the development with sticking becomes more severe, the fixing belt 43 cannot be smoothly fed, and the fixed image is disturbed, or excessive torque is applied to the driving roller 45 to cause jamming of the recording material P. .

  For this reason, in the fixing device 40, a heat-resistant fluorine-based lubricant is applied as a heat-resistant lubricant to the fixing belt 43, and the fixing belt 43 and the heater 41 are rubbed with each other while the fluorine-based lubricant is interposed. I am letting. A fluorine-based lubricant is applied to the inner surface of the fixing belt 43 in order to ensure good slidability with the heater 41 and the nip forming member 42. The belt member (43) rotates in a state where a grease-like heat-resistant lubricant containing fluorine-based fine particles and fluorine-based oil adheres to the inner surface.

  In this example, heat-resistant grease MOLYKOTE (registered trademark) HP300 manufactured by Toray Dow Corning Co., Ltd. was used.

  However, the fluorine oil, which is one of the main components of the fluorine-based lubricant, is heated in the fixing nip N and is subjected to a shearing force, and gradually receives fluorine-based fine particles (PTFE: polytetrafluoro) mixed as a thickener. From the ethylene), and evaporation and thermal decomposition are accelerated by the heat of the heater 41 and lost. For this reason, as the operation time accumulates, the fluorine-based lubricant gradually deteriorates and the lubrication performance decreases, and abnormal noise and vibration due to the stick-and-slip described above are generated. If abnormal noise or vibration is generated, the fixing device 40 is replaced with a new one before the output image is affected. This causes an increase in maintenance costs and a reduction in the operating rate of the image forming apparatus.

  By the way, such deterioration of the fluorine-based lubricant has also occurred in the conventional fixing device in which the sliding surface of the heater 41 is glass-coated. However, in the case of the configuration of FIG. 2 in which the ceramic structure surface of the heater 41 is not coated with glass, it has been found that abnormal noise and vibration are generated at a very early stage than when the glass coating is performed.

  Therefore, in the following embodiment, by reducing the chance of contact of the fluorine-based lubricant with the ceramic structure surface of the heater 41, the deterioration progress of the fluorine-based lubricant is delayed, and abnormal noise and vibration due to a decrease in lubrication performance occur. It is difficult to provide a long-life fixing device.

<Example 1>
FIG. 5 is an explanatory diagram of the state of the interface between the fixing belt and the heater. FIG. 6 is an explanatory diagram of a method for assembling the fixing belt assembly. In FIG. 5, (a) shows the case where the silicone oil is applied to the heater, and (b) shows the case where it is not applied.

  In Example 1, silicone oil was used as a non-volatile liquid that showed immiscibility with the fluorine oil. The fixing belt sliding surface of the heater 41 is impregnated with silicone oil. Silicone oils are excellent in heat resistance, hardly mixed with fluorine oils, and show clear separation properties when left with stirring and mixing. For this reason, the silicone-based oil can reduce the chance that the fluorine-based oil comes into contact with the ceramic structure surface of the heater 41 and prevents the fluorine-based oil from separating from the fluorine-based lubricant, thereby deteriorating the fluorine-based lubricant. Suitable for delaying.

  That is, it is considered that the cause of the separation phenomenon of the fluorinated oil causing the deterioration of the fluorinated lubricant is that the fluorinated oil component is sucked into the micropores scattered on the ceramic structure surface of the heater 41. Yes. Here, the fluorinated oil itself is a substance whose molecular structure is very stable and hardly decomposed at an operating temperature of 200 ° C. or lower. However, when it contacts the high-temperature metal atoms while being absorbed by the micropores on the surface of the ceramic structure and expanding the surface area, the molecular structure of the fluorinated oil is degraded by its catalytic action, the boiling point decreases, and it gradually evaporates. It is thought to be lost.

  Therefore, in the first embodiment, liquids that are harder to decompose than fluorine-based oil are sucked in advance into innumerable minute holes on the ceramic structure surface of the heater 41, thereby reducing the room for fluorine-based oil to be sucked into the minute holes. ing. A liquid whose decomposability on the ceramic structure surface at the operation temperature of the fixing nip N is lower than that of fluorine-based oil is used. By covering the wall surface of the micropores with a liquid that is difficult to be decomposed, the chance of contact of the fluorine-based lubricant with the fluorine-based oil is reduced, and the decomposition is suppressed. By making the fluorinated oil component of the fluorinated lubricant difficult to be absorbed into the micropores existing on the surface of the ceramic heater, the conveyance performance of the fixing device 40 is reduced due to deterioration of the fluorinated lubricant containing the fluorinated oil. Delay. Prevents abnormal noise, fixed image distortion, jamming of recording materials, and high quality images that can be formed over a long period of time due to poor transport performance, and is less likely to cause defects due to deterioration of the fluorine-based lubricant. A long-life fixing device 40 is realized.

  FIG. 5 schematically shows an enlarged cross section of the fixing nip N in the vicinity of the heater 41 of FIG. As shown in FIG. 5A, the heater 41 is provided with a heating resistor layer 46 on the surface opposite to the sliding surface with respect to the fixing belt 43. A surface of the heater 41 is impregnated with a silicone-based oil 47, and a fluorine-based lubricant 48 is applied between the heater 41 and the fixing belt 43. For this reason, the rubbing interface between the heater 41 side and the fixing belt 43 side is formed between the layer impregnated with the silicone oil 47 and the fluorine lubricant 48. It is difficult to contact the ceramic structure surface.

  If the nip forming member 42 is removed while the image formation is accumulated, accumulation of the fluorine-based lubricant 48 is observed on the upstream side and the downstream side of the surface of the heater 41 in the rotation direction of the fixing belt 43. For this reason, it is assumed that in this portion, the fluorine-based lubricant 48 is divided into the heater 41 side and the fixing belt 43 side to form a rubbing interface.

  Further, it is considered that the silicone oil 47 is sufficient if it has a function of filling the micropores on the ceramic structure surface of the heater 41. However, considering that the fluorine-based lubricant 48 pressed against the heater 41 is kneaded on the ceramic structure surface, the ceramic structure surface has an affinity equal to or higher than that of the fluorine-based lubricant 48. Is preferred. This is because the silicone oil (liquid) 47 does not replace the fluorine oil on the ceramic structure.

  Further, considering that the fluorinated lubricant into which the silicone oil (liquid) 47 is kneaded is also rubbed against the inner surface of the fixing belt 43, the fluorinated oil has an affinity for the inner surface of the fixing belt 43 with silicone. It is desirable to be equal to or higher than the system oil 47. However, since the application amount of the silicone oil 47 is very small, even when the affinity of the fluorine oil is low, the silicone oil covers the inner surface of the fixing belt 43 and prevents the adhesion of the fluorine lubricant 48. It is not considered.

  On the other hand, as shown in FIG. 5B, when the surface of the heater 41 is not impregnated with silicone oil, the rubbing interface between the heater 41 side and the fixing belt 43 side is between the heater 41 and the fluorine system. It is formed between the lubricant 48. The fluorine-based lubricant 48 is always in contact with the ceramic structure surface of the heater 41. More precisely, a part of the fluorine-based lubricant 48 is held on the surface of the heater 41, while the surface of the fixing belt 43 holds the fluorine-based lubricant 48. As the fixing belt 43 rotates, the fluorine-based lubricant 48 held on the surface of the heater 41 is kneaded on the high-temperature ceramic structure surface of the heater 41. For this reason, the fluorinated oil separated from the fluorinated lubricant 48 is sucked into the micropores in the ceramic structure surface, and the lubricating performance of the fluorinated lubricant 48 is lowered.

  As shown in FIG. 6A, in the method of manufacturing the fixing device 40, in the first step, the rubbing surface of the heater 41 member fixed to the nip forming member 42 so that the ceramic structure surface is the rubbing surface. A silicone-based oil is applied to the entire surface using a brush. At this time, since excess oil may go around the end portion and enter the fixing nip N, the excess oil may be wiped off with a nonwoven fabric.

  In the second step, the fluorine-based lubricant 48 is placed in a band shape using a dispenser on the rubbing surface to which the silicone oil is applied. In the third step, the heater 41 on which the fluorine-based lubricant 48 was placed was inserted into the fixing belt 43 and then pressed vertically against the inner surface of the fixing belt 43 from below. In this way, the fixing belt 43 is assembled to the heater 41 fixed to the nip forming member 42, and then assembled to the fixing device (40: FIG. 2) and operated, so that the entire inner surface of the fixing belt 43 is formed. The fluorine-based lubricant 48 was thinly spread.

  In Example 1, about 40 mg of silicone oil KF965-1000CS was uniformly applied to the entire surface of the heater 41 opposite to the heating resistor layer (413a, 413b: FIG. 4) with a brush. Thereafter, 1 g of heat-resistant grease / MOLYKOTE (registered trademark) HP300 was applied thereon.

  In Example 1, silicone-based oil refers to oil whose main chain is composed of siloxane bonds (Si—O—Si). In Example 1, dimethyl silicone oil (KF965-1000CS) manufactured by Shin-Etsu Chemical Co., Ltd. was used as an example of silicone oil.

  Here, whether or not to mix with fluorinated oil is simply examined by whether or not the fluorinated lubricant and silicone oil are mixed in an equal amount in a container and stirred and then left to stand. Can do. Even if the fluorine-based oil HP300 and the silicone-based oil KF965-1000CS in Example 1 are mixed in equal amounts, they are separated in a few minutes.

  Then, the silicone oil having a property that does not mix with the fluorine oil HP 300 is filled in the micro holes on the ceramic structure surface of the heater 41, so that the fluorine oil does not easily penetrate into the heater 41. Therefore, the penetration of the oil component of the fluorine-based lubricant into the heater 41, which has been a problem, can be prevented, and the decrease in the lubricity of the fluorine-based lubricant due to the decrease in the oil component can be prevented.

  Note that other silicone oils other than KF965 also have heat resistance of 200 ° C. or higher that can withstand the heating of the heater 41, and exhibit the same effects as in Example 1 if not mixed with the above-described fluorine oil. To do.

<Effect of Example 1>
FIG. 7 is an explanatory diagram of the application effect of silicone oil. FIG. 8 is an explanatory diagram of an experimental result of fixing belt squeal.

  The effect of the silicone oil in Example 1 will be described. In the following description, the heater 41 is an aluminum nitride ceramic heater, and the silicone oil 47 is KF965-1000CS. The fluorine-based lubricant 48 is MOLYKOTE (registered trademark) HP300, and the main components are fluorine-based oil and PTFE powder.

  As shown in FIG. 7, the weight increase caused by the heater 41 sucking the fluorine oil of the silicone oil 47 or the fluorine lubricant 48 was examined. Apply fluorine lubricant 48 (HP300) alone, silicone oil 47 (KF965) alone, and silicone lubricant 47 (KF965) on the entire rubbing surface of heater 41. Samples of three patterns were prepared with the above. After heating each sample at 250 ° C. for 2 hours, the silicone oil 47HP300 and the fluorine-based lubricant 48 were wiped off from the heater 41 with a nonwoven fabric. Each numerical value in FIG. 7 is a difference value obtained by measuring the weight of the subsequent heater 41 and subtracting the dry weight before coating. This difference value is assumed to be the amount of oil penetrated into the heater 41.

  According to FIG. 7, by impregnating the heater 41 with the silicone oil 47 first, the amount of fluorine oil impregnated in the heater 41 (that is, the weight reduction amount of the fluorine lubricant 48) can be reduced to about 40%. confirmed.

  As shown in FIG. 8, in the image forming apparatus 10 shown in FIG. 1, an experiment for comparing the fixing device 40 of Example 1 with the fixing devices of the conventional example and the comparative example was performed. In the fixing device 40 of Example 1, the fluorine-based lubricant 48 (HP300) was applied on the silicone-based oil 47 (KF965). In the fixing device 40 of the conventional example, the fluorine-based lubricant 48 (HP300) is directly applied to the heater 41. In the fixing device 40 of Comparative Example 1, only the silicone oil 47 was applied to the heater 41. In the fixing device 40 of Comparative Example 2, only the thickener (PTFE powder) of the fluorine-based lubricant 48 was applied to the heater 41.

  Then, an actual continuous copy (image formation) is performed, and an experiment is performed in which the rotational speed of the fixing belt 43 is decreased by performing idling operation at each stage of the cumulative number of image formations. The rotational speed was measured. The horizontal axis of FIG. 8 is a value obtained by converting the time when each fixing device 40 is operated into the number of sheets of A4 paper that have been continuously copied. The vertical axis in FIG. 6 summarizes the generation speed of abnormal noise that occurs as a malfunction when the fluorine oil of the fluorine-based lubricant 48 decreases and the lubrication performance deteriorates.

  That is, generally, the lower the rotational speed of the fixing belt 43, the easier the squeal phenomenon occurs. When the lubrication performance of the fluorinated lubricant 48 decreases, the upper limit of the rotational speed at which the squeal phenomenon occurs increases. The abnormal noise of the squeaking phenomenon sounds like the fixing belt 43 squeals with a low sound due to a decrease in slidability between the fixing belt 43 and the heater 41. This phenomenon is defined as the noise of the fixing belt 43. The squeal of the fixing belt 43 gradually starts at a faster speed as the number of accumulated image formations increases. Each measurement point in FIG. 8 plots the fixing belt rotation speed that starts to squeeze when the rotation speed of the fixing belt 43 is gradually decreased under the condition that the temperature of the fixing belt 41 is constant.

  As shown in FIG. 8, as the cumulative number of image formations increases, the fixing belt speed at which the fixing belt 43 squeals gradually increases. Here, the lowest 80 mm / sec among the multi-step process speeds that can be selected by the image forming apparatus 10 is indicated by a broken line in FIG.

  Then, the number of A4 size recording materials that can be fixed before the squealing phenomenon occurs on the fixing belt 43 is 170,000 sheets in the conventional example, but about 280,000 sheets in the first embodiment, which is an increase of about 60% (lifetime). It was confirmed that

  Further, in Comparative Example 1 (□) and Comparative Example 2 (x), since there is almost no effect of suppressing the squealing phenomenon of the fixing belt 43, the fluorine lubricant is effective for the squealing phenomenon of the fixing belt 41. It is a fluorinated oil which is the main component of 48.

  Therefore, when the fluorine-based lubricant is in direct contact with the ceramic structure surface of the heater as in Example 1, it is effective to impregnate the rubbing surface with silicone-based oil. By preventing the fluorine oil of the fluorine lubricant from seeping into the ceramic structure and separating from the fluorine lubricant, it becomes easier to maintain the lubrication performance of the fluorine lubricant, and the slidability between the heater and the fixing belt over a long period of time Can be kept. As a result, it is possible to provide a fixing device that is less prone to problems such as abnormal noise, image disturbance, and drive unit damage.

40 fixing device, 41 heater, 42 nip forming member, 43 fixing belt 44 stay, 45 pressure roller, 46 heating resistor layer 47 silicone-based oil, 48 fluorine-based lubricant P recording material

Claims (5)

A belt member; a drive member that contacts the outer surface of the belt member to rotate the belt member; a heater member that heats the belt member while sliding a ceramic texture surface against the inner surface of the belt member; A support member disposed along a longitudinal direction of the heater member and supporting the heater member; and the belt member is interposed between the heater member and the drive member by urging the support member toward the drive member. An image heating apparatus including a biasing mechanism for sandwiching, and a grease-like heat-resistant lubricant containing fluorine oil interposed between the heater member and the belt member,
An image heating apparatus characterized in that a liquid which is non-volatile at an operating temperature and immiscible with the fluorinated oil covers the ceramic structure surface.   The image heating apparatus according to claim 1, wherein the liquid has lower decomposability in the ceramic structure surface at the operating temperature than the fluorinated oil.   The image heating apparatus according to claim 2, wherein the liquid has a higher affinity for the ceramic structure surface than the fluorine-based oil and a lower affinity for the inner surface of the belt member than the fluorine-based oil. . The ceramic texture surface is aluminum nitride,
The image heating apparatus according to claim 1, wherein the liquid is a silicone-based oil. Applying a silicone-based oil to the rubbing surface of the heater member fixed to the support member so that the ceramic structure surface is a rubbing surface;
A second step of placing a heat-resistant lubricant on the rubbing surface coated with silicone oil;
And a third step of assembling a belt member on the heater member on which the heat-resistant lubricant is placed.

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