JP2005317519A - Heating device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat fixing device (a heating device) having a lubricating grease for maintaining the running stability of a heat resistant film, and an image forming apparatus provided with the heat fixing device, wherein the heating device prevents the occurrence of image inferiority caused by jamming or slipping, suppresses the increase of the driving torque of the device, and prevents the step-out of a driving motor. <P>SOLUTION: A thickener in a lubricant grease 210 held in the heating device by a film heating system contains 30 to 50 weight% of polytetrafluoroethylene having a secondary coagulated particle diameter of 10 to 30 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heating device that pressurizes and heats a material to be heated, and in particular, an image heating fixing device mounted on an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, that is, formed and supported on a recording material. The present invention relates to a heating device suitable for use as a fixing device that heat-fixes an unfixed image, and an image forming apparatus including the heating device as an image heating fixing device.

  Conventionally, as a fixing device of an image output device such as a copying machine, a printer, or a facsimile using an electrophotographic technique, a heat roller type heat fixing device is generally used. This heat roller type heat fixing device is composed of a fixing roller as a fixing body that is heated by a built-in heat source such as a halogen heater and maintained at a predetermined temperature, and a pressure roller that has elasticity and presses against the pressure roller. A pressure roller as a body, and a recording material carrying an unfixed toner image is introduced into a fixing nip portion, which is a pressure nip portion formed between the fixing roller and the pressure roller, and is nipped and conveyed. The unfixed toner image is thermally fixed on the recording material by heat from a fixing roller.

  Recently, a film heating type heating apparatus has been proposed and put into practical use as an image heating fixing apparatus (see, for example, Patent Documents 1 to 7). In this heating apparatus, a material to be heated is closely attached to a heating body fixedly supported by a support member via a heat-resistant and thin film material, and the film material is slid and moved to the heating body so that the heat energy of the heating body is increased. It is configured to be applied to a heated material through a film material, and a recording material on which an unfixed toner image is formed and supported as a heated material is passed through to permanently fix the unfixed toner image on the surface of the recording material. It can be used as an apparatus for heat fixing processing as an image.

  In addition, this film heating type heating device, for example, a device that heats a recording material carrying a toner image to modify the surface property, a device that performs a hypothetical dressing process, and other heat treatments for a sheet-like heated material Can be widely used as a device.

  Such a film heating type heating device (image heating and fixing device) has a low heat capacity, such as an insulating and high thermal conductivity ceramic substrate, and the surface of the substrate as a heating body. A so-called ceramic heater having a resistance heating layer that generates heat when energized as a basic component can be used, and a thin film with a low heat capacity can be used as a film material. The temperature can be raised, and it is not necessary to supply power to the heating element during standby, and even if the recording material as the material to be heated passes immediately, the heating element is predetermined until the recording material reaches the fixing nip. The temperature can be raised sufficiently to shorten the wait time (quick start: on-demand operation) and power savings. Has advantages, such as can be suppressed, it is effective.

  Here, in the heating device of the film heating method, the sliding property between the film and the film support member is ensured by interposing a lubricant (lubricating grease) between the film and the film support member. In the heat fixing apparatus, a stable fixed image can be obtained (for example, see Patent Document 6).

As another power-saving type heating device, an induction heating type heating device has been proposed (see, for example, Patent Document 7). The induction heating method consists of a film in which a heat-resistant resin is formed into a film and a metal thin film and a heat-resistant release layer are formed in sequence, an excitation coil installed inside the film, and a press-contact to the excitation coil across the film. A backup roller that is arranged and driven, and inductively heats the metal thin film layer of the film by an eddy current generated when the excitation coil is energized. A recording material as a material to be heated is interposed between the film and the backup roller. The unfixed image on the recording material is fixed by heat and pressure as a permanently fixed image by passing and heating and pressing.
JP-A-63-313182 Japanese Patent Laid-Open No. 1-263679 Japanese Patent Laid-Open No. 2-157878 JP-A-4-44075 JP-A-4-204980 JP-A-5-27619 JP-A-7-114276

  In general, a heat fixing device reaches about 150 to 200 ° C. in a temperature rising state. In a film heating type device, the room temperature state means parts such as a film conveying means, a coefficient of friction of a heating body surface, and a film suspension conveying roller. It must be taken into consideration that various conditions change until the thermal expansion of the film itself and the viscosity of the lubricating grease interposed between the film and the film supporting member.

  Fluorine-based lubricating grease is known as a lubricating grease that exhibits extremely good stability under severe conditions such as a high temperature environment. In general, as the lubricating grease used in the fixing device of the film heating method, those having a base oil, a thickener, and an additive are used. For example, as the fluorine-based lubricating grease, Perfluoropolyether (PFPE) is used as a base oil, and tetrafluoroethylene (PTFE) homopolymer or copolymer is used as a thickener, and a small amount of additives such as a rust inhibitor are added thereto. There is something.

  However, due to the recent trend toward full-color and high-speed electrophotographic copying machines and printers, high temperature and high pressure are required for heat-fixing devices, and usage conditions are becoming increasingly severe. Also, more excellent characteristics and quality have been demanded for lubricating greases. However, with conventional fluorine-based lubricating grease, the heat-resistant film in the heat-fixing device is continuously scraped under high-temperature and high-pressure environments. If there is a malfunction such as poor rotation stability due to film torque increase due to deterioration or viscosity deterioration of the lubricating grease, or the applied lubricating grease is scraped off by the sliding surface, the lubricating grease will run out after a short period of use. In some cases, the friction coefficient increases and wear proceeds rapidly. As a result, the running stability of the heat resistant film cannot be obtained, and image defects due to, for example, jams or slips occur. Further, since the driving torque of the fixing device is increased, there is a problem that the driving motor is stepped out.

  For example, in the case of a monochrome printer with a relatively low pressure, it is necessary to reduce the cost by attaching the printer body and the heat fixing device to the body (no replacement is required). Therefore, the conditions required for the heat fixing apparatus include durability that can withstand continuous use for a long time. However, as described above, with conventional lubricating grease, it is difficult to realize a long life due to various problems associated with the deterioration of viscosity.

On the other hand, in the case of a color printer that generally requires high gloss, heat fixing under high pressure is required. However, in the heat fixing device that requires high pressure, as described above, there may be a serious problem in the quality such as abnormal noise caused by the shortage of lubricating grease that occurs after a short period of use.
Further, in the fixing device using the endless belt-like heat-resistant film, there is a problem that the lubricating grease oozes out from the end of the heat-resistant film. This is because the base oil in the exuded lubricating grease wraps around the heat-resistant film surface and reacts with the heat-resistant film and the PFA resin layer on the surface of the pressure roller, causing cracks and cracks on the surface layer. This is because the image quality may be deteriorated. This is because the base oil contained in the lubricating grease penetrates between the polymer spherulites of the heat-resistant film or PFA resin layer on the surface of the pressure roller, moves the molecules, and adds mechanical stress such as subsequent rotation. This is considered to cause cracks or cracks in the PFA resin layer.

  Therefore, it is necessary to suppress the seepage of lubricating grease and base oil from the end of the heat resistant film.

  The present invention has been proposed in view of the above, and it is possible to maintain the rotational stability or running stability of the film even when used for a long time with respect to the heating device of the film heating system, and suppress the increase in friction and wear. And a heating device capable of suppressing the base oil component from flowing into the surface of the heat-resistant film from the lubricating grease that has oozed out from the end of the heat-resistant film, and the heating device as a fixing device to form an image. An object is to provide an apparatus.

  The present invention is a heating device and an image forming apparatus having the following configurations.

(1) a film, a support member that has a sliding surface on which the film slides and supports the film, and a pressure member that sandwiches the film to form the pressure contact nip portion with the sliding surface In the heating device that heats the material to be heated while being nipped and conveyed between the film and the pressure member of the pressure nip portion while sliding the film on the sliding surface,
A heating apparatus comprising a lubricant containing a fluororesin powder having an average secondary agglomerated particle size of 10 to 30 μm interposed between the sliding surface and the film.

(2) a film, a supporting member that has a sliding surface on which the film slides and supports the film, and a pressure member that sandwiches the film and forms the press-contact nip portion. In the heating device that heats the material to be heated while being nipped and conveyed between the film and the pressure member of the pressure nip portion while sliding the film on the sliding surface,
A heating apparatus, wherein a lubricant containing a fluororesin powder having a specific surface area of 3 to 20 m <2> / g is interposed between the sliding surface and the film.

(3) a film, a support member that has a sliding surface on which the film slides and supports the film, and a pressure member that sandwiches the film and forms the press-contact nip portion. In the heating device that heats the material to be heated while being nipped and conveyed between the film and the pressure member of the pressure nip portion while sliding the film on the sliding surface,
The pressure nip portion is formed at a pressure of 1.0 × 10 5 Pa (1 Pa = 1 N / m ² ) or more per unit area, and an average secondary aggregate particle size is 10 to 30 μm between the sliding surface and the film. A heating apparatus characterized by interposing a lubricating grease containing a fluororesin powder.

(4) a film, a supporting member having a sliding surface on which the film slides and supporting the film, and a pressure member sandwiching the film to form the pressure nip portion with the sliding surface. In the heating device that heats the material to be heated while being nipped and conveyed between the film and the pressure member of the pressure nip portion while sliding the film on the sliding surface,
The pressure nip is formed at a pressure of 1.0 × 105 Pa or more per unit area, and a lubricating grease containing fluororesin powder having a specific surface area of 3 to 20 m 2 / g is interposed between the sliding surface and the film. A heating device characterized in that

  (5) The heating apparatus according to (2) or (4), wherein the fluororesin powder is a powder having an average secondary agglomerated particle size of 10 to 30 μm.

  (6) The lubricant is a lubricating grease composition containing at least a base oil and a thickener, and the lubricating grease contains 30 to 50% by weight of fluororesin powder (1) Thru | or the heating apparatus in any one of (5).

  (7) The heating apparatus according to any one of (1) to (6), wherein polytetrafluoroethylene (PTFE) powder is used as the fluororesin powder.

(8) The heating apparatus according to any one of (1) to (7), wherein the film is a rotating film, and the pressure member is a rotating member.
(9) The heating apparatus according to any one of (1) to (8), wherein the film has a release layer made of a fluororesin.

  (10) The heating apparatus according to any one of (1) to (8), wherein the pressure member has a release layer made of a fluororesin.

(11) The heating device according to any one of (1) to (8), wherein the film and the pressure member have a release layer made of a fluororesin.
(12) The heating device according to any one of (1) to (8), wherein a heating body is disposed on the sliding surface.

  (13) The heating apparatus according to any one of (1) to (9), wherein the heated material is a recording material carrying an image.

  (14) The heating apparatus according to any one of (1) to (9), wherein the apparatus is an image heat fixing apparatus that heat-fixes an unfixed image formed on a recording material.

  (15) An image forming unit that forms an unfixed image on a recording material, and a fixing unit that heat-fixes the unfixed image formed on the recording material, wherein the fixing unit is any one of (1) to (9) An image forming apparatus comprising the heating apparatus according to claim 1.

  That is, a powder of polytetrafluoroethylene having a secondary agglomerated particle size of 10 to 30 μm as a thickener in a lubricant (lubricant grease) interposed between the sliding surface of the film heating type heating device and the film By using a material containing 30 to 50% by weight, the effect of maintaining excellent slidability for a long time even under a high temperature and high pressure environment can be obtained.

  This is because the polytetrafluoroethylene powder has a larger average secondary agglomerated particle size than the conventional one, and the base oil in the lubricating grease is added between the primary agglomerated particles constituting the secondary agglomerated particles. The surface area that can be included increases, and the base oil can be prevented from flowing out of the lubricating grease in a short time.

  Further, since the thickener in the lubricating grease used in the present invention, that is, the polytetrafluoroethylene powder having a secondary aggregate particle size of 10 to 30 μm, can effectively contain the base oil, the consistency of the lubricating grease Tends to be small, and also has an effect of preventing the base oil from exuding from the end of the heat-resistant film and the pressure-resistant roller, which causes wrinkles on the surface of the pressure roller.

  When the blending amount of the polytetrafluoroethylene fine powder in the lubricating grease is less than the specified range of 30 to 50% by weight, the base oil may flow out of the lubricating grease in a short time. Further, when the blending amount is larger than the specified range, the amount of base oil in the lubricating grease is relatively reduced, which adversely affects the lubricating action such as an increase in rotational torque, and sufficiently achieves the object of the present invention. Can not do it.

  Although the conventional lubricating grease also uses polytetrafluoroethylene powder in the form of secondary agglomerated particles as a thickener, the average secondary agglomerated particle size of the secondary agglomerated particles is less than 5 to 10 μm, It was smaller than 10-30 micrometers specified by this invention. In the past, emphasis was placed on viscosity, and the base oil retention after durability at high temperatures and pressures was not focused. It has been found that a thicker agent is more advantageous as a thickener at high pressure. When the average secondary agglomerated particle size is less than 10 μm, the durability is NG (Table 1), and when it exceeds 30 μm, the initial torque UP is NG.

In addition, regarding a lubricant containing a fluororesin powder having a specific surface area of 3 to 20 m 2 / g, the specific surface area of the fluororesin powder contained in the lubricant is 2 m 2 / g. It was less than 3-20 m2 / g specified in the present invention.
7) → There is nothing in particular. I was not conscious of using it under high pressure conditions. When it is smaller than 3 m 2 / g, it is NG due to a decrease in durability, and when it is larger than 20 m 2 / g, it is NG when the torque is increased.

(1) Example of Image Forming Apparatus FIG. 1 is a schematic cross-sectional model diagram for explaining a configuration of a main part of an example of an image forming apparatus using a film heating type heating apparatus according to the present invention as a fixing device. The image forming apparatus of this example is a laser beam printer using a transfer type electrophotographic process.

  Reference numeral 101 denotes a photosensitive drum, and a photosensitive material such as OPC, amorphous Se, or amorphous Si is formed on a cylindrical substrate such as aluminum or nickel. The photosensitive drum 101 is rotationally driven in the direction of the arrow, and first, the surface thereof is uniformly charged by a charging roller 102 as a charging device. Next, the uniformly charged surface of the photosensitive drum 101 is subjected to scanning exposure by the laser beam L which is ON / OFF controlled according to image information by the laser scanner unit 103, and the electrostatic latent image is converted into the electrostatic latent image. Formed on the surface. This electrostatic latent image is developed and visualized by the developing device 104. As a developing method, a jumping developing method, a two-component developing method, a FEED developing method (Floating Electrode Effect Development) or the like is used, and image exposure and reversal development are often used in combination. The visualized toner image is transferred onto the transfer material P conveyed at a predetermined timing from a paper feeding mechanism (not shown) to a transfer nip T which is a contact portion between the photosensitive drum 101 and the transfer roller 5 as a transfer device. Is transferred from the surface of the photosensitive drum 101 by the transfer roller 5. At this time, the transfer material P is nipped and conveyed between the photosensitive drum 101 and the transfer roller 105 with a constant pressure. The transfer material P onto which the toner image has been transferred at the transfer nip T is separated from the surface of the photosensitive drum 101 and conveyed to the fixing device 106 where it is fixed as a permanent image. On the other hand, residual toner remaining on the photosensitive drum 101 is removed from the surface of the photosensitive drum 101 by the cleaning device 107.

(2) Fixing Device FIG. 2 is a schematic cross-sectional model view of a heat fixing device 106 as a heating device used in this example. FIG. 3 is an enlarged model view of the fixing nip portion. The heat-fixing device 106 of this example is a so-called tensionless type film heating method / pressure rotating body (pressure roller) drive described in JP-A-4-44075-44083, JP-A-4-2048080-204984, and the like. This is a heating device of the type.

  Reference numeral 201 denotes a heating body, and the heating body in this example is a so-called ceramic heater (hereinafter referred to as a low-heat capacity) having a horizontally long and thin wall with a direction perpendicular to the sheet passing direction as a longitudinal direction in the sheet passing path surface of the recording material P. (Referred to as a heater).

  As shown in the model diagram of FIG. 3, the heater 201 generates heat by the heat conduction / insulation substrate (heater substrate) 202 made of alumina or the like and the energization formed on one side of the heater substrate 202, for example, Ag. Provided on the side opposite to the side on which the resistance layer 203 and the insulating glass coat layer 204 of the heater substrate 202 are provided, the resistance layer 203 such as / Pd, the insulating glass coat layer 204 having a thickness of about 10 μm as the surface protective layer. And thermistor 205 as a temperature detecting element. The heater 201 quickly rises in temperature by supplying power from a power supply source (not shown) to the resistance layer 203, and is adjusted to a predetermined fixing temperature by a power control system (not shown) including the thermistor 205.

  Reference numeral 206 denotes a heater support that supports the heater 201 in a heat-insulating manner. The heater support 206 is a horizontally long member having a substantially semicircular arc shape and a saddle shape in cross section and having a direction perpendicular to the drawing as a longitudinal direction. It is a molded product of a heat resistant resin such as a polymer. The heater 201 is fitted into a heater insertion groove formed along the length of the lower surface of the heater support 206 with the insulating glass coat layer 204 exposed to the outside, and is adhered and held with a heat resistant adhesive. .

  Reference numeral 207 denotes a cylindrical (endless belt-shaped) heat-resistant film made of resin or metal. The cylindrical film 207 is loosely fitted onto and supported by the heater support 206 assembled with the heater 201 described above. In the case of a resin film, the film 207 has a total thickness of 100 μm or less, preferably 60 μm or less and 20 μm or more in order to reduce the heat capacity and improve the quick start property of the apparatus. -PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether), durable single layer film such as PPS, or polyimide, polyamideimide, PEEK (polyetheretherketone), PES (poly A composite layer film in which PTFE, PFA, FEP (tetrafluoroethylene-perfluoroalkyl vinyl ether) or the like is coated as a release layer on the surface of a base film such as ether sulfone).

  Reference numeral 208 denotes a metal U-shaped rigid pressure stay with a downward cross section, which is inserted through the heater support 206.

  Reference numeral 209 denotes an elastic pressure roller as a pressure member, which includes a core metal 209a, a heat-resistant elastic roller portion 209b such as silicon rubber, and a release layer 209c as a surface layer.

  The pressure roller 209 has both ends of the cored bar 209a rotatably supported by bearings between unshown device chassis side plates. On the pressure roller 209, the assembly including the heater 201, the heater support 206, the film 207, the stay 208, and the like is arranged in parallel with the heater 201 facing downward, and both end portions of the stay 208 are disposed on both ends. The heater 201 and the pressure roller 209 are pressed against each other with the film 207 interposed therebetween by pressing the pressure roller 209 against the elasticity of the elastic roller portion 209b of the roller by a not-shown pressure spring (biasing means). Thus, a fixing nip portion N which is a pressure nip portion having a predetermined width is formed by elastic deformation of the pressure roller 209. The pressure roller 209 is driven to rotate in the counterclockwise direction indicated by an arrow at a predetermined peripheral speed when the driving force of the driving means M is transmitted through a power transmission mechanism such as a gear (not shown).

  The film 207 is driven at least at the time of image formation by the pressure roller 209 being rotated counterclockwise as indicated by an arrow, so that the pressure roller 209 and the outer surface of the film 207 are fixed at the fixing nip N by the rotation of the pressure roller 209. Rotational force acts on the film 207 by the frictional force between the film and the inner surface of the film in close contact with the surface of the insulating glass coat layer 204 which is the downwardly exposed surface of the heater 201 in the fixing nip N. While being slid as a sliding surface, the outer circumference of the heater support 206 is rotated in the clockwise direction indicated by the arrow, that is, the conveying speed of the transfer material P carrying the unfixed toner t conveyed from the image transfer unit side. It is rotationally driven at substantially the same peripheral speed.

  The heater support 206 is a member that supports the heater and also functions as a film guide member during film rotation. The heater support 206 is a support member that supports the film 207. The heater 201 provided is the film sliding surface of the support member.

  In the fixing nip portion N, in order to reduce sliding resistance between the inner surface of the film 207 and the surface of the insulating glass coat layer 204 which is the downwardly exposed surface of the heater 201 on which the film 207 slides, a lubricating grease 210 (FIG. 3) is interposed therebetween. ).

  Thus, when the film 207 is rotated by the rotational driving of the pressure roller 209 and the heater 201 rises to a predetermined fixing temperature and is temperature-controlled, the pressure roller 209 in the fixing nip N and the film 207 A transfer material P as a material to be heated having an unfixed toner image t in between is introduced with the toner image carrying surface side of the film 207 side, and is closely attached to the outer surface of the film at the fixing nip N, and is fixed together with the film 207 As the nip portion N is nipped and conveyed, the heat of the heater 201 is applied through the film 207, and the unfixed toner image t is heated on the surface of the transfer material P by receiving the pressure of the fixing nip portion N. Pressure fixing. The transfer material P that has passed through the fixing nip N is separated from the outer surface of the film 207 and conveyed.

  In the film heating type fixing device 106 as in this example, the heating body 201 having a small heat capacity and a high temperature rise can be used, and the time until the heating body 201 reaches a predetermined temperature can be greatly shortened. Since it can be easily raised to a high temperature even from room temperature, it is not necessary to adjust the standby temperature when the apparatus is in a standby state during non-printing, and power can be saved.

  Further, the rotating film 207 has no tension other than the fixing nip portion N, and the film 207 movement restriction means simply accepts the end of the film 207 for reasons such as simplification of the apparatus. Only the flange member is provided.

  Further, under the condition that the pressure at the fixing nip N in this apparatus is 1.0 × 105 Pa or more per unit area, when a color toner fixed at 200 ° C. or less is used, the maximum gloss value is 15 or more. (Use paper: A4 80 g) can be achieved.

(3) Lubricating grease Next, the lubricating grease 210 applied between the heat-fixing device 106 and the surface of the heat-resistant film 207 that contacts the heating body 201 will be described in detail below.

  The lubricating grease composition used in the apparatus of the present invention contains a base oil, a thickener, and an additive, as in a general lubricating grease composition.

3-1) Base oil The base oil of the lubricating grease used in the present invention is not particularly limited, and synthetic oils such as mineral oil, synthetic hydrocarbon oil, ether oil, and ester oil can be used alone or in combination. It can be used as appropriate. Examples of mineral oils include paraffinic mineral oils and naphthenic mineral oils, synthetic hydrocarbon oils such as poly-α-olefin oils, and ether oils such as dialkyldiphenyl ether oil, alkyltriphenyl ether oil, and alkyltetraphenyl oil. Examples of ether oils include diester oils, polyol ester oils, complex ester oils, and aromatic ester oils. Among these, considering the lubrication performance at high temperature and high speed and the lubrication life, it is desirable to contain a synthetic oil, and it is particularly desirable to contain an ester oil and an ether oil.

3-2) Thickener As the thickener for the lubricating grease used in the present invention, fluorine resin fine powder is preferable, and polytetrafluoroethylene fine powder is particularly used. The average secondary agglomerated particle size of the polytetrafluoroethylene fine powder is 10 to 30 μm. The polytetrafluoroethylene fine powder is blended in the base oil so that the blending amount is 30 to 50% by weight.

3-3) Additives Further, the lubricating grease used in the present invention includes an antioxidant, a rust inhibitor, a metal corrosion inhibitor, an oil formulation, and the like, as long as the object of the present invention is not impaired. Additives such as antiwear agents, extreme pressure agents, and solid lubricants can be contained.

(4) Experimental Results Next, experimental results using the lubricating greases 1 to 4 based on Example 1 of the present invention and the lubricating greases 5 and 6 used as comparative examples will be described.

  The average agglomerated particle size of the polytetrafluoroethylene fine powder is measured with a laser diffraction particle size distribution measuring device (SALD-7000, manufactured by Shimadzu Corporation).

4-1) Lubricating grease 1 as an example
Perfluoropolyether (PFPE) is used as the base oil of the lubricating grease 210 applied between the heat-resistant film 207 and the surface in contact with the heating body 201, and polytetrafluoroethylene fine powder ( What added 30% by weight of the average secondary agglomerated particle size of 10 to 14 μm) was uniformly stirred, and then kneaded with a three-roll mill was used as “lubricating grease 1”.

4-2) Lubricating grease 2 as an example
It was prepared in the same manner as Lubricating Grease 1 except that polytetrafluoroethylene fine powder as a thickener having an average secondary agglomerated particle size of 10 to 14 μm was added and 35% by weight was added to the total amount. 2 ".

4-3) Lubricating grease 3 as an example
A thickening agent, polytetrafluoroethylene fine powder having an average secondary agglomerated particle size of 10 to 14 μm, was added in the same manner as the lubricating grease 1 except that 40% by weight was added to the total amount. Used.

4-4) Lubricating grease 4 as an example
A thickening agent, polytetrafluoroethylene fine powder having an average secondary agglomerated particle size of 10 to 14 μm, was used in the same manner as the lubricating grease 1 except that 50% by weight was added to the total amount. Used.

4-5) Lubricating grease 5 as a comparative example
Perfluoropolyether (PFPE) is used as the base grease of the lubricating grease applied between the heat-resistant film 207 and the surface in contact with the heating body 201, and the polytetrafluoroethylene fine powder is averaged as a thickener. A secondary agglomerated particle size of 7 to 10 μm was prepared in the same manner as the lubricating grease 1 except that 35% by weight based on the total amount was added and used as the “lubricating grease 5”.

4-6) Lubricating grease 6 as a comparative example
Perfluoropolyether (PFPE) is used as the base grease of the lubricating grease applied between the heat-resistant film 207 and the surface in contact with the heating body 201, and the polytetrafluoroethylene fine powder is averaged as a thickener. A secondary agglomerated particle size of 7 to 10 μm was prepared in the same manner as the lubricating grease 1 except that 40% by weight was added to the total amount and used as “lubricating grease 6”.

4-7) Evaluation Each of the above lubricating greases 1 to 6 was evaluated by the following test method. That is, in the heat-fixing device 106 in which each lubricating grease is interposed between the surface of the heat-resistant film 207 in contact with the heating body 201, the heating body temperature is 210 ° C. and the pressing force of the fixing nip portion N is 1 per unit area. The film (fixing rotator) 207 is rotated at a rotational speed of 47 rpm under a pressure of 0.0 × 105 Pa or more, and the applied lubricating grease 210 deteriorates or the lubricating grease runs out. The time until abnormal noise was generated from the surface in contact with the heating body 201 was measured. The measurement results are shown in Table 1.

  As is apparent from the results in Table 1, in the image forming apparatus provided with the heat fixing device 106 to which a high pressure is applied, the average secondary of the polytetrafluoroethylene fine powder, which is a thickener contained in the lubricating grease 210, is obtained. By using a lubricating grease having an aggregate particle size of 10 to 30 μm and containing 30 to 50% by weight of the same fine powder, it prevents the lubricating grease from running out in a short time of use, and exhibits excellent slidability. be able to.

  In the case of a secondary aggregated particle size range of 25 to 30 μm (added amount: 35 wt%), the evaluation was ◎ at an endurance time of 400 h. When the secondary aggregate particle size range exceeds 30 μm, the device torque increases due to the increase in the viscosity of the grease, which is not preferable.

(1) Fixing Device FIG. 4 is a schematic cross-sectional model view of a heat fixing device as a heating device used in this example. The heat fixing device 309 of this example is an induction heating type heating device.

  Reference numerals 301 and 305 denote a high permeability magnetic core and an exciting coil constituting magnetic field generating means, which are disposed in a lower film guide member 302a having a substantially semicircular arc shape in cross section. The magnetic core 301 may be made of a material used for a transformer core such as ferrite or permalloy, and more preferably ferrite having a low loss even at 100 kHz or higher. The exciting coil 305 is formed into a boat shape.

  Reference numeral 302b denotes an upper film guide member having a substantially semicircular arc-shaped cross section disposed over the lower film guide member 302a. The lower film guide member 302a and the upper film guide member 302b are substantially cylindrical. The body is composed. The upper film guide member 302b can be omitted.

  Reference numeral 303 denotes a rotating body (fixing film) as an electromagnetic induction heat generating member, that is, a cylindrical electromagnetic induction heat generating film (metal film) as an endless belt. The film 303 is loosely fitted outside the assembly of the lower film guide member 302a and the upper film guide member 302b.

  Reference numeral 304 denotes a laterally long pressurizing rigid stay, which is inserted into the inside of the assembly of the lower film guide member 302a and the upper film guide member 302b, and the lower film guide member 302a in which the magnetic core 301 and the exciting coil 305 are disposed. The magnetic core 301 and the pressurizing rigid stay 304 are disposed in contact with each other via an insulating member 306 for insulating between the magnetic core 301 and the pressurizing rigid stay 304.

  Reference numeral 307 denotes a pressure roller as a pressure member, which includes a cored bar 307a and a heat resistant and elastic material such as silicone rubber, fluororubber, and fluororesin that is concentrically formed and coated around the cored bar 307a. It is composed of a material layer 307b, and both ends of the cored bar 307a are rotatably supported and supported between chassis side metal plates (not shown) of the apparatus.

  On the pressure roller 307, the lower film guide member 302a, the exciting coil 305, the magnetic core 301, the insulating member 306, the pressing rigid stay 304, the upper film guide member 302b, and the electromagnetic induction heat generating film 303 are provided. Etc. are arranged in parallel with the lower surface of the lower film guide member 302a facing downward, and both end portions of the stay 304 are respectively moved to the pressure roller 307 side by pressure springs (biasing means) (not shown). By pressing against the elasticity of the elastic roller portion 307b of the roller, the lower surface of the lower film guide member 302a and the pressure roller 307 are brought into pressure contact with the film 303 interposed therebetween, and a predetermined width is obtained by elastic deformation of the pressure roller 307. The fixing nip portion N, which is a pressure nip portion, is formed. The pressure roller 307 is driven to rotate in the counterclockwise direction indicated by an arrow at a predetermined peripheral speed when the driving force of the driving means M is transmitted through a power transmission mechanism such as a gear (not shown).

  A rotational force acts on the film 303 by a frictional force between the pressure roller 307 and the outer surface of the film 303 by the rotation driving of the pressure roller 307, and the film 303 has a film guide member 302 a at the fixing nip portion N. The outer surface of the film guide member 302a and the upper film guide member 302b are rotated at a peripheral speed substantially corresponding to the rotational peripheral speed of the pressure roller 307 in the clockwise direction indicated by the arrow while sliding closely with the lower surface of the manual surface as a manual surface. It will be in a rotating state.

  In order to reduce the mutual sliding frictional force between the lower surface of the lower film guide member 302a and the inner surface of the film 303 at the fixing nip portion N, the lower surface of the lower film guide member 302a and the inner surface of the film 303 are fixed. A lubricating grease 309 is interposed therebetween.

  The lower film guide member 302a presses the fixing nip N, supports the magnetic core 301 and the exciting coil 305, and supports the film 303 in cooperation with the upper film guide member 302b. It plays a role of improving the conveyance stability.

  The exciting coil 305 in the lower film guide member 302a is connected to an exciting circuit (not shown) at its power feeding portion. This excitation circuit can generate a high frequency of 20 kHz to 500 kHz by a switching power supply. The exciting coil 305 generates an alternating magnetic flux by an alternating current (high-frequency current) supplied from an exciting circuit. The electromagnetic induction heat generating film 303 generates electromagnetic induction heat by the action of the generated magnetic flux. Reference numeral 308 denotes a temperature sensor such as a thermistor for detecting the temperature of the pressure roller 307. In this example, the temperature sensor 308 controls the temperature of the fixing nip N in consideration of the temperature information of the pressure roller 307. Yes.

  Thus, the film 303 is rotated by the rotation drive of the pressure roller 307, and the film 303 is electromagnetically heated by supplying an alternating current to the exciting coil 305, so that the fixing nip portion N is adjusted to a predetermined fixing temperature. In this state, a transfer material P as a heated material having an unfixed toner image t is introduced between the pressure roller 307 and the film 303 in the fixing nip N with the toner image carrying surface side of the film 303 side. The fixing nip portion N is in close contact with the outer surface of the film, and the fixing nip portion N is nipped and conveyed together with the film 303, so that the heat of the film 303 is applied and the pressing force of the fixing nip portion N is received. The unfixed toner image t is fixed to the surface of the transfer material P by heat and pressure. The transfer material P that has passed through the fixing nip N is separated from the outer surface of the film 303 and conveyed.

(2) Lubricating grease The lubricating grease used in the fixing device of this embodiment will be described.

2-1) Lubricating grease 7
Perfluoropolyether (PFPE) is used as the base grease of the lubricating grease 309 applied between the lower surface (film sliding surface) of the lower film guide member 302a and the inner surface of the film 303, and the ratio is used as a thickener. Manufactured in the same manner as “Lubricating grease 1” in Example 1 except that 40% by weight of polytetrafluoroethylene fine powder (average secondary agglomerated particle size 10 to 14 μm) having a surface area of 10 m 2 / g was added to the total amount And used as “lubricating grease 7”.

  The polytetrafluoroethylene fine powder was synthesized by an emulsion polymerization method, and a specific surface area / pore distribution measuring device (Asap 2020 manufactured by Micromeritics) was used for measuring the specific surface area.

2-2) Lubricating grease 8
Perfluoropolyether (PFPE) is used as the base grease of the lubricating grease applied between the lower surface of the lower film guide member 302a and the inner surface of the film 303, and the specific surface area is 1.2 m 2 / g as a thickener. This was prepared in the same manner as “Lubricating grease 1” in Example 1 except that 40% by weight of polytetrafluoroethylene fine powder (average secondary agglomerated particle size 7 to 10 μm) was added to the total amount. 8 ".

  The polytetrafluoroethylene fine powder was synthesized by a suspension polymerization method, and a specific surface area / pore distribution measuring device (Asap 2020 manufactured by Micromeritics) was used for measuring the specific surface area.

(3) Evaluation In this example, the above “lubricating grease 7” and “lubricating grease 8” were evaluated by the following test methods.

  In the heat fixing device 309 in which each lubricating grease is interposed between the lower surface of the lower film guide member 302a and the inner surface of the film 303, the temperature of the fixing nip portion N is 210 ° C., and the pressure per unit area of the fixing nip portion N is set. Under the condition of 2.1 × 105 Pa, the film 303 (fixing rotating body) is rotated at a rotational speed of 47 rpm, and the applied lubricating grease deteriorates or the lubricating grease runs out. The time until abnormal noise was generated from the surface in contact with the surface was measured. The measurement results are shown in Table 2.

  As is apparent from the results in Table 2, the specific surface area of the polytetrafluoroethylene fine powder, which is a thickener contained in the lubricating grease, is 3 to 20 m 2 / g, and the average secondary agglomerated particle size is 10 to 30 μm. By using the lubricating grease containing 30 to 50% by weight, even if the sliding surface with the film is not a heating body as in Example 1, the base oil is effectively applied to the surface. It becomes possible to hold, and it is possible to suppress the lubrication grease running out in a short time use and to exhibit excellent slidability.

  When the specific surface area was 4 m 2 / g and the addition amount was 40 wt%, the durability time was 450 h, and the evaluation was good. When the non-surface area exceeds 20 m <2> / g, the device torque increases due to an increase in the viscosity of the grease, which is not preferable.

  The present embodiment uses an induction heating type heat fixing apparatus similar to that in the second embodiment, in which the pressure per unit area of the fixing nip N is 0.7 × 10 5 Pa. When the same verification was performed on “lubricating grease 1 to 6” and “lubricating grease 7.86” in Example 2, Tables 3 and 4 were obtained.

  As is apparent from the results in Table 3, polytetrafluoroethylene, which is a thickener contained in the applied lubricating grease, in the heat fixing device having a pressure per unit area of the fixing nip N of 0.7 × 105 Pa. Lubricating grease 1 to 4 having an average secondary agglomerated particle size of fine powder of 10 to 30 μm and containing 30 to 50% by weight in the lubricating grease maintains excellent slidability in a high temperature environment for an extremely long time. be able to.

  Lubricating grease 5 (comparative example) and lubricating grease 6 (comparative example) are conventional lubricating greases.

  Further, in the case of a secondary aggregated particle size range of 25 to 30 μm (added amount 35 wt%), the durability time was 400 h, and the evaluation was ◎. When the secondary aggregate particle size range exceeds 30 μm, the device torque increases due to the increase in the viscosity of the grease, which is not preferable.

  As is clear from the results in Table 4, in the heat fixing apparatus having a pressure per unit area of the fixing nip N of 0.7 × 105 Pa, polytetrafluoroethylene which is a thickener contained in the applied lubricating grease Lubricating grease 7 having an average secondary agglomerated particle size of fine powder of 10 to 30 μm, 30 to 50% by weight in the lubricating grease, and having a specific surface area of the thickener of 3 to 20 m 2 / g, Excellent slidability in a high temperature environment can be maintained for an extremely long time.

When the specific surface area was 4 m ² / g and the addition amount was 40 wt%, the durability time was 450 h, and the evaluation was good. When the non-surface area exceeds 20 m ² / g, the device torque increases due to an increase in the viscosity of the grease, which is not preferable.

From the above verification, when a heat fixing device having a pressure per unit area of the fixing nip N of 0.7 × 10 ⁵ P is used, the gloss can be lowered, but the durability can be dramatically improved. It was. That is, it can be used as a low-cost main body additional heat fixing device (replacement unnecessary).

  This example is a film heating type heating apparatus similar to that in Example 1, and between the heat-resistant film 207 and the side in contact with the heating element 201, “lubricating grease 1-6” in Example 1 and Example 2 After applying “lubricating greases 7 and 8” in FIG. 1, the pressure per unit area of the fixing nip portion N is maintained for a predetermined time with a pressure of 2.1 × 105 Pa applied to the surface of the heat-resistant film. It was measured whether the base oil wraps around. The evaluation method is rank ○ when no seepage of lubricating grease or base oil from the end of the heat-resistant film is observed, and rank ○ △ when no seepage of lubricating grease or base oil from the end of the heat-resistant film is observed. When the lubrication grease or base oil reached the pressure roller, rank Δ, and when the lubrication grease or base oil entered within the image width, rank x was observed every hour.

  This evaluation was made by observing the seepage of lubricating grease or base oil when the film (fixing rotating body) 207 was rotated at a rotational speed of 47 rpm with the heating body temperature set at 195 ° C. It has been confirmed by previous studies that the amount of grease or base oil that oozes out is saturated in about 5 hours.

  Tables 5 and 6 show the evaluation results.

  As is apparent from the results of Table 5, in the heat fixing apparatus having a pressure per unit area of the fixing nip N of 2.1 × 10 5 Pa, polytetrafluoroethylene which is a thickener contained in the applied lubricating grease The average secondary agglomerated particle size of the fine powder is 10 to 30 μm, and the lubricating grease 1 to 4 contained in the lubricating grease in an amount of 30 to 50 wt. However, after that, the state of seeping out of the lubricating grease did not change, and the lubricating grease did not reach the pressure roller.

  As is apparent from the results of Table 6, in the heat fixing apparatus having a pressure per unit area of the fixing nip N of 2.1 × 10 5 Pa, polytetrafluoroethylene which is a thickener contained in the applied lubricating grease Lubricating grease 7 having an average secondary agglomerated particle size of fine powder of 10 to 30 μm, 30 to 50% by weight in the lubricating grease, and having a specific surface area of the thickener of 3 to 20 m 2 / g, Even after 5 hours from the start of evaluation, no seepage of lubricating grease or base oil was observed.

[Others]
1) In the film heating type heat fixing device 106 (FIGS. 2 and 3) in the first embodiment, the heating element 201 is not limited to a ceramic heater. For example, a contact heating body using a nichrome wire or the like, or an electromagnetic induction exothermic member such as an iron plate piece may be used. The heating body 201 does not necessarily have to be located in the fixing nip portion (pressure nip portion).

  2) In the electromagnetic induction heating type fixing device 309 (FIG. 4) in the second embodiment, the magnetic flux generating means 301 and 305 can be configured to be disposed outside the film 303 as an electromagnetic induction heat generating member. .

  3) In the heat fixing apparatus according to the first or second embodiment, the film 207 or 303 may be configured to be stretched between a plurality of suspension members and rotated by a driving roller. Further, the film 207 or 303 may be a long-end member having a roll wound around the feeding shaft, and the apparatus may be configured to travel and move to the winding shaft side.

  4) The pressurizing member is not limited to the roller body, and may be in the form of a rotating endless belt body or the like.

  5) The heating device of the present invention is not limited to the heat-fixing device of the embodiment. In addition, an image heating device that presupposes an unfixed image, and a recording medium that carries the image is reheated to improve the surface properties such as gloss. It can also be used as a heat treatment apparatus such as drying, heat laminating, hot press wrinkle removal, hot press curl removal, etc. by passing a sheet-like heated material other than a recording medium.

1 is a schematic cross-sectional model diagram of an example of an image forming apparatus in Embodiment 1. FIG. 1 is a schematic cross-sectional model view of a heat fixing device in Embodiment 1. FIG. It is an enlarged model view of a fixing nip portion. 6 is a schematic cross-sectional model view of a heat fixing device (induction heating method) in Embodiment 2.

Explanation of symbols

In FIG. 1: 101 .. Photosensitive drum, 102 .. Charging roller, 103 .. Laser scanner unit, 104... Development device, 105... Transfer roller, 106 .. Fixing device, 107. 3: 201 .. Heating body, 202 .. Good thermal conductive substrate, 203 .. Resistance layer, 204 .. Insulating glass coat, 205 Thermistor, 206 .. Heater support, 207 .. Heat resistant film, 208. Stay, 209 ..Pressure roller, 210 ..Lubricating grease, P ..Recording material, t..Toner In FIG. 3: 301 ..Magnetic core, 302 a ..Lower film guide member, 302 b. Members 303 .. fixing film 304 stays 305 exciting coils 306 insulating members 307 pressure rollers 30 a ... metal core, 307b ... elastic material layer, 308 ... thermistor 309 ... lubricating grease, P ... recording medium, t ... toner

Claims (15)

A film, a supporting member that has a sliding surface on which the film slides and supports the film, and a pressure member that sandwiches the film and forms a pressure nip portion with the sliding surface. In a heating apparatus that heats while sandwiching and conveying a material to be heated between the film and the pressure member of the pressure nip portion while sliding and moving on the sliding surface,
A heating apparatus comprising a lubricant containing a fluororesin powder having an average secondary agglomerated particle size of 10 to 30 μm interposed between the sliding surface and the film. A film, a supporting member that has a sliding surface on which the film slides and supports the film, and a pressure member that sandwiches the film and forms a pressure nip portion with the sliding surface. In a heating apparatus that heats while sandwiching and conveying a material to be heated between the film and the pressure member of the pressure nip portion while sliding and moving on the sliding surface,
A heating apparatus, wherein a lubricant containing a fluororesin powder having a specific surface area of 3 to 20 m <2> / g is interposed between the sliding surface and the film. A film, a supporting member that has a sliding surface on which the film slides and supports the film, and a pressure member that sandwiches the film and forms a pressure nip portion with the sliding surface. In a heating device that heats while sandwiching and conveying a material to be heated between the film and the pressure member of the pressure nip portion while sliding and moving on the sliding surface,
Lubrication including fluororesin powder having an average secondary agglomerated particle size of 10 to 30 μm between the sliding surface and the film, wherein the pressure nip is formed at a pressure of 1.0 × 10 5 Pa or more per unit area. A heating apparatus characterized by interposing grease. A film, a supporting member that has a sliding surface on which the film slides and supports the film, and a pressure member that sandwiches the film and forms a pressure nip portion with the sliding surface. In a heating device that heats while sandwiching and conveying a material to be heated between the film and the pressure member of the pressure nip portion while sliding and moving on the sliding surface,
The pressure nip is formed at a pressure of 1.0 × 105 Pa or more per unit area, and a lubricating grease containing fluororesin powder having a specific surface area of 3 to 20 m 2 / g is interposed between the sliding surface and the film. A heating device characterized in that   The heating apparatus according to claim 2 or 4, wherein the fluororesin powder is a powder having an average secondary agglomerated particle size of 10 to 30 µm.   6. The lubricating grease composition comprising at least a base oil and a thickener, wherein the lubricating grease contains 30 to 50% by weight of fluororesin powder. The heating apparatus in any one of.   The heating apparatus according to claim 1, wherein a powder of polytetrafluoroethylene (PTFE) is used for the fluororesin powder.   The heating apparatus according to claim 1, wherein the film is a rotating film, and the pressure member is a rotating member.   The heating apparatus according to claim 1, wherein the film has a release layer made of a fluororesin.   The heating device according to any one of claims 1 to 8, wherein the pressure member has a release layer made of a fluororesin.   9. The heating apparatus according to claim 1, wherein the film and the pressure member have a release layer made of a fluororesin.   The heating apparatus according to claim 1, wherein a heating body is disposed on the sliding surface.   10. The heating apparatus according to claim 1, wherein the heated material is a recording material carrying an image.   10. The heating apparatus according to claim 1, wherein the apparatus is an image heating and fixing apparatus that heat-fixes an unfixed image formed on a recording material.   The image forming means for forming an unfixed image on a recording material and the fixing means for heat-fixing the unfixed image formed on the recording material, wherein the fixing means is any one of claims 1 to 9. An image forming apparatus, which is a heating device.