JP2008158053A - Fixing belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing belt having improved paper peelability and an improved drive durability and being capable of obtaining high gloss and high image quality. <P>SOLUTION: Regarding the fixing belt, the polyimide layer thereof contains a filler, the filler is at least one kind of filler selected out of a group constituted of carbon, metal, ceramic and fluoro-resin. The polyimide layer contains the filler, such as carbon, then, functionability, such as conductivity, heat-conductivity and slidability can be imparted, and further, the hardness thereof is controllable. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a fixing belt having a polyimide layer, and is particularly useful as a fixing belt of an electrophotographic image forming apparatus such as a copying machine, a laser beam printer, or a facsimile.

Conventionally, polyimide resin materials have been put to practical use in a wide range of fields from aerospace to electrical and electronic materials because of their high mechanical strength and heat resistance. Among them, seamless tubular bodies made of polyimide resin include functional belts such as fixing belts, transfer belts, intermediate transfer belts, conveyance belts, and photoreceptor belts of electrophotographic image forming apparatuses such as copying machines, laser beam printers, and facsimile machines. It is used as a base material. In particular, in the fixing belt, the transfer body is conveyed while pressure-heating the unfixed toner image. Therefore, the strength that can withstand the tension between the driving rolls, the heat resistance that can withstand the heating temperature of the roll, and the belt end. When controlling the shift, a rigidity that does not cause buckling or tearing is required.

  More recently, with the shift to oil-less, it has become impossible to set a claw for separating the paper, and instead the paper is peeled off using the curvature, so the tension of the stretched belt is flexible. Sex is important. In addition, in order to cope with high speed and high image quality, the toner must be sufficiently wrapped around the belt surface, so that flexibility of the belt surface is also required.

  As a solution to these problems, Patent Document 1 proposes a fixing member having a silicone rubber elastic layer having an E hardness of 15 to 65 degrees.

JP 2003-122164 A

  However, the hardness specified for the belt described in Patent Document 1 is a part of the configuration of the fixing member, and is not sufficient for obtaining high-speed and high-quality images, and the durability of the belt body and the wear resistance of the surface are not sufficient. Was not enough.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing belt that is excellent in paper peelability and driving durability, and can obtain high gloss and high image quality.

  The present inventors have intensively studied to achieve the above object, and as a result, have found that this can be achieved by the present invention as follows, and have completed the present invention.

  The fixing belt of the present invention is characterized by having a release layer on the outer periphery of the polyimide layer and a viscoelastic layer on the inner periphery. Since the polyimide layer has appropriate flexibility, even when a composite belt is used, the belt end surface is hardly roughened when the belt is cut. Further, by having the viscoelastic layer, it is possible to reduce the curvature even when stretched by a roll, and it is possible to obtain a fixing belt excellent in paper peelability and driving durability. In addition, since there is a release layer on the outer periphery of the polyimide layer, there is a hard polyimide layer as a base even in a release layer that is relatively easy to wear, such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). As a result, it is possible to obtain a fixing belt which is not easily damaged by wear and has excellent driving durability.

  In the fixing belt of the present invention, the polyimide layer contains a filler, and the filler is at least one selected from the group consisting of carbon, metal, ceramic and fluororesin. By containing a filler such as carbon, functions such as conductivity, thermal conductivity, and slidability can be imparted, and the hardness can be controlled.

  The fixing belt according to the present invention has a folding strength of 5000 times or more. When the folding strength is a predetermined number or more, a fixing belt having excellent flexibility and a long belt life can be obtained.

  The fixing belt of the present invention has a loss elastic modulus of 20 GPa to 80 GPa and a surface hardness of 0.1 GPa to 0.22 GPa. When the loss elastic modulus and the surface hardness are in the predetermined ranges, a fixing belt excellent in paper peelability and toner particle followability can be obtained.

The fixing belt of the present invention includes a polyimide layer, and can be manufactured, for example, by the following method. First, the polyamic acid solution is applied to the inner surface of the cylindrical mold by moving the cylindrical mold in the axial direction of the dispenser supply portion while rotating, and leveling and defoaming by a centrifugal method. Regarding the application, the polyamic acid solution may be attached to the inner surface of the mold with a dispenser or the like, and then finished to a predetermined thickness with a hard sphere or the like. Next, the polyamic acid solution is solidified or hardened by heating or solvent extraction or the like, and is further obtained by imide conversion by heating at a high temperature.

  Below, the preparation method of a polyimide acid solution is demonstrated.

<Preparation of polyamic acid solution>
A known polyamic acid solution can be used, and a polyamic acid solution obtained by polymerizing a tetracarboxylic dianhydride or its derivative (an acid anhydride) and a diamine in a solvent is used. When the aromatic polyimide resin is used, a belt having suitable mechanical strength and heat resistance can be obtained.

Examples of suitable acid anhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-
Examples thereof include naphthalene tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride and the like.

On the other hand, examples of diamines include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3 , 3′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl-4,4′-biphenyldiamine, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenylpropane and the like can be mentioned.

  A suitable solvent can be used as a solvent for the polymerization reaction of the acid anhydride and diamine, but a polar solvent is preferably used from the viewpoint of solubility. Specifically, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine, dimethyl sulfoxide, tetramethylene sulfone, dimethyltetramethylene sulfone and the like can be mentioned. These may be used alone or in combination. Furthermore, phenols such as cresol, phenol and xylenol, benzonitrile, dioxane, butyrolactone, xylene, cyclohexane, hexane, benzene, toluene and the like can be mixed alone or in combination with the organic polar solvent.

  A polyamic acid solution is obtained by reacting the acid anhydride (a) and the diamine (b) in the organic polar solvent. Here, the polyamic acid (polyimide precursor) can be obtained by reacting approximately equimolar amounts of acid anhydride and diamine in an organic solvent. The monomer concentration (concentration of (a) + (b) in the solvent) at that time is set according to various conditions, but is preferably 5 to 30% by weight. The reaction temperature is preferably set to 80 ° C. or less, particularly preferably 5 to 50 ° C., and the reaction time is preferably 0.5 to 10 hours. If the reaction time is less than 0.5 hours, the reaction becomes insufficient, and if the reaction time exceeds 10 hours, no further effect can be obtained.

  Although the viscosity of the polyamic acid solution obtained by the above reaction increases, if the heating is performed as it is, the viscosity of the polyamic acid solution decreases. Utilizing this phenomenon, the polyamic acid solution can be adjusted to a predetermined viscosity. The heating temperature at this time is preferably 50 to 90 ° C.

<Preparation of polyimide layer>
The preparation method of a polyimide layer is demonstrated by the method shown below using the said polyamic acid solution.

  First, a catalyst is added to and mixed with the polyamic acid solution. These are supplied into a cylindrical mold, and uniformly developed by centrifugal force on the inner peripheral surface of the mold by a rotary centrifugal molding method. At this time, the viscosity of the solution is preferably 1 to 1000 Pa · s (23 ° C.), more preferably 5 to 500 Pa · s (23 ° C.) with a B-type viscometer. If it is less than 1 Pa · s, so-called sagging or repelling of the coating layer is likely to occur, and uniformity of the coating film thickness cannot be obtained, which is not preferable. On the other hand, if it exceeds 1000 Pa · s, it is necessary to apply a high pressure at the time of discharge, and the leveling effect by centrifugal molding becomes difficult to occur, which is not preferable.

  In addition, although the rotation speed of the metal mold | die circumferential direction performed in order to perform centrifugal molding also depends on the diameter of a metal mold | die, the viscosity of a polyamic acid solution, and an application state, 100 rpm-5000 rpm are preferable. If it is less than 100 rpm, the leveling effect and defoaming effect of the coating film due to centrifugal force are difficult to obtain, and if it exceeds 5000 rpm, the mechanical load increases, causing eccentricity of the mold due to vibration, and in the longitudinal direction of the mold. The coating thickness is not uniform, which is not preferable.

  Next, the polyamic acid solution is heated at a high temperature of 300 to 450 ° C. to advance the ring-closure imidization reaction (imide conversion) and then taken out from the mold. It is necessary to perform the solvent removal and the heating during the imidization reaction evenly. As a method of heating evenly, there are a method of heating while rotating the mold, a method of improving the circulation of hot air, and a method of charging at a low temperature to reduce the rate of temperature rise. In addition to the method described above, imide conversion is performed by removing the belt-like material that can maintain the shape of the polyamide acid solution in the mold heated and solidified from the mold, and inserting this belt-shaped material into a metal pipe. Instead, a method of performing imide conversion may be used.

  The imide conversion may be carried out by any of the above method of heating at a high temperature or the method of adding a catalyst alone or a catalyst and a dehydrating agent in combination to a polyamic acid solution and heating at a low temperature. If it does not specifically limit.

  Further, when preparing a polyimide layer, when a magnetic metal is dispersed in a raw material and the magnetic metal is heated by electromagnetic induction, since it is close to the surface in contact with the toner, its thermal efficiency is high and energy saving is possible.

  Examples of the catalyst include imidazoles, secondary amines, and tertiary amines. Specific examples include 2-methylimidazole, 4-methyl-2-phenylimidazole, 2-phenylimidazole, imidazole, And isoquinoline. Of these, isoquinoline is more preferred. The addition amount of the catalyst is preferably 0.1 to 2 molar equivalents, more preferably 0.2 to 1 molar equivalents relative to 1 molar equivalent of the polyamic acid in the polyamic acid solution. Further, these catalysts are effective as an imidization accelerator at a low temperature even in heat imidization without using a dehydrating agent.

  Examples of the dehydrating agent include organic carboxylic acid anhydrides, N, N′-dialkylcarbodiimides, lower fatty acid halides, halogenated lower fatty acid anhydrides, arylphosphonic acid dihalides, and thionyl halides.

  The thickness of the polyimide layer is preferably set to be in the range of 50 μm to 200 μm. If the thickness of the polyimide layer is less than 50 μm, the rigidity of the belt end portion is lost with respect to the load applied when the deviation is controlled, and the belt tends to buckle, which is not preferable. On the other hand, if it exceeds 200 μm, the separation roll, which is one of the rolls to be stretched, increases the radius of curvature of the belt, which is not preferable because the toner on the belt is not sufficiently released.

  The filler contained in the polyimide layer is preferably at least one selected from the group consisting of carbon, metal, ceramic, and fluororesin. In order to obtain desired characteristics, by including a filler, for example, functions such as conductivity, thermal conductivity, and releasability can be imparted, and the hardness can be controlled.

  Specific examples of carbon include channel black, furnace black, ketjen black, and acetylene black. These can be used alone or in combination of two or more.

  Further, depending on the application, it is preferable to use carbon black that has been prevented from oxidative degradation such as oxidation treatment and grafting treatment, and that has improved dispersibility in a solvent, and in particular, oxidized carbon black is used. It is preferable.

  By adding the carbon to the polyimide layer, conductivity and thermal conductivity can be imparted.

  Examples of the metal include metals such as silver, copper, aluminum, and nickel, and alloys thereof.

  Examples of the ceramic include diamond, glass, alumina, magnesium oxide, boron nitride, beryllium oxide, tin oxide, and indium oxide.

  Fluororesin includes polytetrafluoroethylene (PTFE) and its modified products, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoro Propylene copolymer (FEP), tetrafluoroethylene-vinylidene fluoride copolymer (TFE / VdF), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (EPA), polychlorotrifluoroethylene ( PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), chlorotrifluoroethylene-vinylidene fluoride copolymer (CTFE / VdF), polyvinylidene fluoride (PVdF), polyvinyl fluoride Fluorine resin such as nil (PVF).

  The coefficient of friction can be adjusted by adding the fluororesin to the polyimide layer. Controlling the friction coefficient to 0.05 to 0.35 is effective because it can reduce frictional wear and prevent slipping and the like.

  In the present invention, the content of the filler is appropriately determined depending on the type of filler to be added depending on the purpose, but the fixing belt or the like is 1 to 50 relative to the polyimide resin solid content due to its mechanical strength and the like. It is preferable that it is weight%, More preferably, it is 10-30 weight%. When the content of the filler is less than 1% by weight, the effect of adding the filler cannot be obtained. On the other hand, if it exceeds 50% by weight, the mechanical strength of the belt tends to decrease.

  Furthermore, like a polyimide layer, fillers, such as carbon and a fluororesin, can be added to a viscoelastic layer and a mold release layer according to the objective.

  The fixing belt of the present invention has a release layer on the outer periphery of the polyimide layer and a viscoelastic layer on the inner periphery. When there is a polyimide layer under the release layer and a viscoelastic layer under it, the surface release layer has excellent wear resistance and high speed specifications because it has a hard polyimide layer under the surface release layer. Suitable for fixing belts. Furthermore, the thing which added the fluororesin etc. to the said viscoelastic layer, and provided the slidability, and the thing which has a sliding layer on a viscoelastic layer can be mentioned.

<Preparation of viscoelastic layer>
By having a viscoelastic layer, flexibility is imparted to the fixing belt, and a high-quality and high-gloss belt can be obtained due to the flexibility of the belt surface. This is particularly effective when color toner is used.

  The material of the viscoelastic layer is preferably a material that can withstand the fixing temperature, and includes natural rubber, synthetic rubber, silicone rubber, fluororubber, and the like, more preferably silicone rubber and fluororubber. In addition, those having a small amount of volatile components such as low molecular siloxane, unreacted monomer, and low molecular compound are particularly preferable. The softness of these rubbers can be controlled by crosslinking and foaming.

  As a method for coating the viscoelastic layer, for example, methods such as spray coating, spin coating, roll coating, brush coating, dipping, and dispenser coating are conceivable.

  Although the thickness of a viscoelastic layer is not specifically limited, 100 micrometers-1500 micrometers are preferable. If the thickness is less than 100 μm, it tends to be difficult to fuse the toner uniformly, and if it exceeds 1500 μm, the thermal conductivity, electrical conductivity, and mechanical properties of the entire belt tend to deteriorate.

<Preparation of release layer>
By having the release layer, it is possible to obtain a fixing belt having excellent release properties, wear resistance, and the like.

  Although it does not specifically limit as a material of a mold release layer, The mold release layer containing a fluororesin is preferable. The fluororesin is not particularly limited as long as it contains a fluorine atom in the molecule. Specifically, polytetrafluoroethylene (PTFE) and its modified product, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene Copolymer (FEP), tetrafluoroethylene-vinylidene fluoride copolymer (TFE / VdF), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (EPA), polychlorotrifluoroethylene (PCTFE) , Chlorotrifluoroethylene-ethylene copolymer (ECTFE), chlorotrifluoroethylene-vinylidene fluoride copolymer (CTFE / VdF), polyvinylidene fluoride (PVdF), polyvinyl fluoride ( VF) and the like. PTFE, PFA, or a mixed system thereof is preferred from the viewpoints of wear resistance, releasability from toner, and heat resistance.

As a method of forming a release layer such as a fluororesin on the outer periphery of the polyimide layer of the present invention, a method of depositing a tubular seamless belt obtained by melt extrusion on the outer surface of the tubular inner layer, a solution (including dispersion) Is formed on the outer surface of the tubular inner layer.

  The thickness of the release layer is preferably 5 μm to 100 μm. If the thickness is less than 5 μm, the life cycle is short and disadvantageous, and if it exceeds 100 μm, cracks tend to occur.

  Moreover, the thing etc. which interpose the primer layer between each layer can be mentioned. As the primer layer, various commercially available primers that enhance adhesion between the polyimide layer, the viscoelastic layer, the release layer, and the like can be used, and a polyimide-based primer is preferably used.

  The thickness of the primer layer is preferably in the range of 0.5 to 10 μm. If it is less than 0.5 μm, the binding force is low, and if it exceeds 10 μm, it tends to be brittle.

<Fixing belt>
A fixing belt (composite belt) composed of the polyimide layer, viscoelastic layer, release layer, and the like can be prepared by the method described above.

  The thickness of the entire fixing belt in the present invention is not particularly limited as long as the characteristics as a belt are exhibited, but generally, the total thickness is preferably set in a range of 50 μm to 400 μm. If it is less than 50 μm, it tends to buckle.

  The folding strength (MIT) of the fixing belt (composite belt) of the present invention is preferably 5000 times or more, and more preferably 10,000 times or more. Important properties in the mechanical properties in fixing include the elastic modulus, tear strength, and folding strength of the belt, and folding strength is particularly important. In order to maintain the releasability of the paper, it is necessary to reduce the curvature at a part of the belt circumference, but if the flexibility is inferior, the belt life is shortened. Accordingly, the folding endurance is preferably 5000 times or more, and if it is less than 5000 times, depending on the system, the accumulated paper passing should be 100,000 sheets or more in an apparatus having a paper feeding speed of 20 to 50 ppm. become unable.

  The loss elastic modulus of the fixing belt of the present invention is preferably 20 GPa to 80 GPa, and more preferably 35 GPa to 75 GPa. If it is less than 20 GPa, the effect of the elastic component is weak, the restoration is slow with respect to deformation, and the fixing belt as a rotating body is not preferable because the pressure reproducibility cannot be obtained. On the other hand, if it exceeds 80 GPa, the effect of the viscous component in the belt component is weak, and it cannot follow the unevenness of the paper and tends to be uneven in gloss after image output.

  Further, when used as a fixing belt, it is necessary to include micron-order toner and melt it sufficiently. Therefore, it is necessary to apply uniform heat and pressure to the fixing belt of the present invention. The uniform heat is determined by the thickness accuracy of the belt and the dispersibility of the thermally conductive filler, but the surface hardness is an important factor for obtaining a uniform pressure. Accordingly, the hardness of the belt surface is preferably 0.1 GPa to 0.22 GPa, and more preferably 0.15 GPa to 0.21 GPa. If it is less than 0.1 GPa, the wear properties are inferior, which is not preferable. On the other hand, if it exceeds 0.22 GPa, inclusion and melting of the toner are insufficient, and gloss cannot be obtained.

  When the layers of the fixing belt (composite belt) in the present invention are viewed individually, the hardness of the polyimide layer is preferably 1 GPa to 5 GPa. When the hardness is less than 1 GPa, not only the wear resistance effect of the release layer on the surface (periphery), for example, the PFA layer on the surface, is reduced, but the support is weak and is likely to buckle during driving. On the other hand, if it exceeds 5 GPa, the effect of the viscoelastic layer hardly appears and becomes brittle, and the belt end tends to tear.

  The hardness of the viscoelastic layer is preferably 0.01 GPa to 0.1 GPa. If it is less than 0.01 GPa, the restoring force is weak against deformation, which is not preferable. On the other hand, if it exceeds 0.1 GPa, the viscosity effect is weak, and it cannot follow the unevenness of the paper and tends to be uneven in gloss after image output.

  The fixing belt of the present invention is required to have a charge eliminating function for the purpose of preventing sticking of paper due to electrification, and this can be performed by making the inner surface of the belt conductive. In this case, the surface resistance is preferably 5 (log Ω / □) or less as a common logarithmic value.

  The friction coefficient of the inner surface of the fixing belt is preferably 0.05 to 0.4, though it depends on the type of the inner member. If the friction coefficient is less than 0.05, slip occurs between the rolls to be stretched, and if it exceeds 0.4, it becomes easy to avoid by applying an excessive driving force, which is not preferable. Moreover, when providing a viscoelastic layer in the inner periphery of the polyimide layer in this invention, in order to suppress a frictional resistance, heat resistant resins, such as a polyimide and a polyamide, can be coat | covered.

  Further, as the fixing speed increases, distortion of the fixing belt easily occurs. In particular, a difference in rotational speed is likely to occur near the center in the longitudinal direction of the belt and at both ends due to the effects of pressure difference and temperature difference. This speed difference causes image misalignment and paper twist, which is not preferable. Therefore, it is a preferable aspect to reduce the speed difference by forming an inverted crown shape in which the central portion of the belt is slightly narrower than both ends. Here, the circumferential length at the center of the belt and the circumferential length at the end portion are preferably 1: 1.001 to 1: 1.010, though depending on the speed difference of the apparatus actually used. In addition, it is good to perform a circumference difference gradually. Further, by providing a gradual circumferential length difference, it is preferable that a reverse crown shape is applied to the inner mold used when heating polyimide, so that the precision can be easily processed.

  The fixing belt of the present invention can be used in a fixing unit of an image forming apparatus such as a copying machine, a facsimile, or a printer, but can be used in any system as long as the fixing unit adopts a belt fixing method. For example, it can be used for a system in which a fixing belt is stretched between rolls, a system in which a tubular fixing belt is supported by an appropriate stay or the like. The present invention can achieve high durability even in the case of high-speed paper feeding. In addition, due to the excellent releasability, it has high gloss and high image quality, so it can sufficiently cope with full color image.

Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, the evaluation item in an Example etc. measured with the following measuring apparatus and measurement conditions.

(1) Tensile modulus Measuring device: manufactured by Orientec, UTM1000 Tensilon, or equivalent product Chuck interval: 30 mm
Tensile speed: 100 mm / min Tensile modulus calculation method: calculated from the slope of the maximum tangent of the stress-strain curve Specimen: JIS K 6301 punched with No. 3 dumbbell is used.

(2) Tear strength The tear strength is determined according to the JIS K 7128-1 trouser tear method. Take the length of the test piece in the belt axis direction, and put a slit of 75 ± 1 mm in the center of the width. Next, the leg of the test piece is attached to the chuck and pulled under the following conditions by a tensile tester.
Sample: 150 mm long x 75 mm wide (with a 75 ± 1 mm slit)
Tensile speed: 20 mm / min

(3) Coefficient of friction Measuring device: AFT-15B manufactured by Orientec
Mating material: φ10 steel ball Speed: 150mm / min Load: 200g

(4) Surface resistance A four-probe probe (MCP-TP03P) connected to Loresta-GP (Mitsubishi Chemical) was pressed against the belt surface for measurement.

(5) Loss elastic modulus Measuring device: ARES, manufactured by Rheumatics
Jig: Thin film Mode: Temp-Ramp
Temperature: 25-250 ° C
Frequency: 1Hz
Distortion amount: 0.2%
Pre-tension: about 1.77N
Length: 70-80mm
Width: 3mm

(6) Hardness Thin film physical property evaluation apparatus: manufactured by NEC Sanei, MHA-3000
Indenter: Diamond triangular pyramid ridge angle 80 degrees, tip diameter 2μm
Indentation depth: 1 μm
Measurement was performed at an indentation speed of 21 nm / second.

(7) Fixation evaluation and glossiness
Sample: After a dry toner is uniformly placed on plain paper, a belt cut to 40 mm x 80 mm is covered so that the release surface is on the toner side. Next, the belt / toner / plain paper is introduced between heated rolls. After passing through the roll, the belt was removed, and the glossiness of the toner fixed on the paper was measured according to JIS Z8741.
Heating temperature: 200 ° C for both upper and lower rolls
Paper feed speed: 40 mm / sec Device: 50 N
Measurement size: 20 °: 10.0 mm x 10.6 mm
60 °: 10.0mm × 20.0mm

(8) Abrasion resistance Measured according to the JIS K 7128 abrasion test method. The belt was affixed and fixed to a hollow cylindrical jig, the belt surface (PFA surface) was pressed against plain paper, the hollow cylindrical jig was rotated, and the amount of wear (mg / hr) after 1 hour was measured.
Load: 50N
Rotation speed: 500mm / sec

<Example 1>
To 1500 g of N-methyl-2-pyrrolidone (NMP), 80 g of carbon black (XC-72, manufactured by Cabot) is added (carbon black is 22% by weight in the polyamic acid solution). About 1 mol of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine, which is a diamine component, are dissolved in an approximately equimolar amount (monomer concentration: 20% by weight). Then, the mixture was stirred while being heated to 70 ° C. to prepare a polyamic acid solution having a viscosity of 200 Pa · s by a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd., BH) at 23 ° C. Further, isoquinoline as a catalyst was added to the polyamic acid solution so as to be 1% by weight, and mixed and stirred.

  Next, while fixing the rectangular die-type dispenser, the polyamic acid solution is moved from one end to the other end of the cylindrical die while rotating the cylindrical die having a length of 600 mm and a diameter of 80 mmφ. The coating was applied spirally to the inner surface of the cylindrical mold, and the unevenness of the wrapping portion of the coating film surface was leveled while rotating the mold at 3000 rpm for 3 minutes to obtain a uniform coating film surface. Next, while rotating the mold at 60 rpm, the solvent was removed stepwise to 220 ° C. to remove the solvent.

  The belt base material before imide conversion was released from the cylindrical mold, replaced with an aluminum pipe, and heated at 400 ° C. for 20 minutes to perform imide conversion. The resulting polyimide belt had a length of 580 mm, an outer diameter of 80 mmφ, and a thickness of 75 μm.

  Next, a primer (manufactured by Mitsui DuPont Fluorochemicals, K001-02) was spray-coated on the outer surface of the belt, and dried to 1 μm. Further, a PFA dispersion liquid (manufactured by Mitsui DuPont Fluorochemicals, ENA-511CL) having a melt flow rate of 1.7 g / 10 minutes (ASTM: D3307) is spray-coated and dried to a thickness of 40 μm. I made it. Further, it was baked at 400 ° C. for 60 minutes. The surface roughness Ra was 0.1 μm.

  The belt was fixed to a mold having the same inner diameter as the above two-layer belt, and methyl silicone rubber (DX35-2083, manufactured by Toray Dow Corning Co., Ltd.) was applied to the inner surface of the polyimide with a dispenser in the same manner as the polyamic acid solution. Thereafter, the mixture was heated and vulcanized to form a viscoelastic layer having a thickness of 200 μm, and a fixing belt was produced.

<Comparative Example 1>
A polyimide belt was obtained in the same manner as in Example 1. A primer (manufactured by Mitsui DuPont Fluorochemicals, K001-02) was spray-coated on the belt, and dried to 1 μm. Further, a PFA dispersion liquid (manufactured by Mitsui DuPont Fluorochemicals, ENA-511CL) having a melt flow rate of 1.7 g / 10 minutes (ASTM: D3307) is spray-coated, heated at 400 ° C. for 20 minutes, and then thick. A release layer having a thickness of 40 μm was formed to prepare a fixing belt.

<Comparative example 2>
In place of the polyimide belt of Example 1, a cylindrical mold made of stainless steel (SUS316) was prepared, and a PFA tube having an inner diameter of 80.5 mmφ (resin 445HP-J, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was opened. Then, methyl silicone rubber (DX35-2120, manufactured by Toray Dow Corning Co., Ltd.) was introduced into the gap while overflowing, and vulcanized at 200 ° C. for 2 hours after filling. The PFA tube was sputtered on the inner surface for 5 seconds under the conditions of an output of 1.5 W, a degree of vacuum of 4.67 Pa, an argon gas flow rate of 0.6 L / min, and a primer (Toray Dow Corning, DX39- 067) was coated to prepare a fixing belt comprising a release layer and a viscoelastic layer.

  The fixing belt having the configuration in Example 1 is a fixing belt that has folding strength, loss elastic modulus, and surface hardness in desired ranges, good paper peelability, high gloss, and high image quality. It was confirmed that there was. On the other hand, since Comparative Example 1 does not have a viscoelastic layer, it was confirmed that the loss elastic modulus exceeded the desired range, the hardness was high, and the glossy belt was not glossy. In Comparative Example 2, since the polyimide layer was not provided, it was confirmed that the loss elastic modulus and bending strength were very weak, the hardness was low, and the amount of wear was large.

Claims (4)

  A fixing belt having a release layer on the outer periphery of the polyimide layer and a viscoelastic layer on the inner periphery. The polyimide layer contains a filler;
The fixing belt according to claim 1, wherein the filler is at least one selected from the group consisting of carbon, metal, ceramic, and fluororesin.   The fixing belt according to claim 1, wherein the folding strength is 5000 times or more.   The fixing belt according to claim 1, wherein the loss elastic modulus is 20 GPa to 80 GPa, and the surface hardness is 0.1 GPa to 0.22 GPa.