JP2007192985A - Fixing belt and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing belt having improved mechanical properties, thermal conductivity, flexibility, and a toner releasing property, and also, having high adhesion among respective layers such as a polymide layer, a metal layer and a releasing layer, and having improved durability, regarding the fixing belt used in a belt fixation system for a printer etc., where the increase of the operating speed and the miniaturization are required. <P>SOLUTION: The fixing belt is constituted by forming the metal layer on the outer surface of a tubular object having a base composed of polymide, and forming the releasing layer on the outer surface of the metal layer. The metal layer is formed of a metal deposit film formed by spray-coating. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing belt used for fixing an unfixed toner image on a transfer sheet by heating and pressurizing in an image forming apparatus such as a copying machine, a printer, and a facsimile using an electrophotographic technique, and a manufacturing method thereof. is there.

  In an image forming apparatus such as a copying machine or a laser beam printer, a thermal roller method has been often used as a method for thermally fixing a toner image on a sheet-like transfer material such as paper at the final stage of printing or copying. However, in recent years, a belt fixing method using a fixing belt has become mainstream from the viewpoint of energy saving.

  An example of these belt fixing systems will be described with reference to FIG. 2. In order to thermally fix the toner image 18 formed on the surface of the copy paper 17, a belt guide 12 and a ceramic heater 13 are provided inside the fixing belt 11, This is a method in which the copy paper 17 on which the toner image 18 is formed is sequentially fed between the pressure roll 14 brought into pressure contact with the ceramic heater 13 via the fixing belt 11 and the toner is heated and melted to be thermally fixed on the copy paper. In this belt fixing system, since the heater substantially directly heats the toner through the fixing belt 11 having a very thin film-like coating, the contact surface N (nip surface) between the fixing belt 11 and the pressure roll 14 is instantaneous. In particular, there is no waiting time until the fixing temperature reaches a predetermined fixing temperature until the fixing state is reached, and the power consumption is small. Reference numeral 15 denotes a thermistor, 19 denotes a fixed toner image, and 16 denotes a cored bar portion of the pressure roll 14.

  Patent Document 1 discloses a fixing belt used in the belt fixing method using a polyimide tubular material having excellent heat resistance and mechanical properties as a base material. Moreover, the thing using metal thin-film tubular goods, such as stainless steel, is disclosed by patent document 2. FIG.

  However, in recent years, printers and copiers have advanced in the direction of higher speed, and the characteristics of the fixing belt used in the belt fixing method are required to be higher than mechanical characteristics, thermal conductivity, heat resistance, and the like, which are disclosed in Patent Document 1. However, the polyimide tubular product has mechanical properties such as strength and buckling which are close to the limits, and there is a problem that the polyimide tubular product is broken from the end, bent when a paper jam occurs, or perforated. Although there is an attempt to increase the mechanical properties by increasing the thickness of the polyimide tubular material against such problems, the thermal conductivity of the tubular material is greatly reduced, which is necessary for heat fixing of the toner. The amount of heat could not be obtained, and the balance between the mechanical properties and the thermal conductivity of the polyimide tubular product was in a state of being compromised for speeding up.

  On the other hand, when a metal thin-film tubular material such as stainless steel provided in Patent Document 2 is used as a fixing belt, it has excellent characteristics in terms of thermal conductivity and mechanical properties, and therefore, speeding up, paper jam, etc. It is possible to cope with troubles. However, recent printers and copiers have been designed with thermal efficiency or compactness in mind, so that a fixing belt having an inner diameter of 20 mm or less has been used. 2 is poor in flexibility, and it is necessary to increase the pressure of the pressure roll 14 in the fixing device of FIG. 2, and damage due to repeated fatigue or bending at the nip surface N between the fixing belt 11 and the pressure roll 14 occurs. There's a problem. Further, when the ceramic heater 13 is broken, the metal thin film tubular body becomes a conductor, and there is a risk of electric leakage. Furthermore, the process for processing into a thin film having a thickness of about 50 μm is complicated, and there is a problem in manufacturing cost.

In order to solve such a problem, Patent Documents 3 and 4 propose a fixing belt in which a metal layer and a polyimide resin layer are laminated.
JP 07-178741 A JP 2002-055557 A Japanese Patent Laid-Open No. 06-222695 JP 2002-292766 A

  The present invention is a fixing belt for use in a belt fixing method of a printer or the like that is increasing in speed, size, and weight, and is excellent in mechanical properties, thermal conductivity, flexibility, and toner releasability. An object of the present invention is to provide a fixing belt having strong durability and excellent durability between the metal layer and the release layer.

  In order to achieve the above object, the fixing belt of the present invention is a fixing belt in which a metal layer and a release layer are formed on the outer surface of a tubular material whose base material is made of polyimide, The layer is characterized in that it is a metal deposited film formed by thermal spraying.

  The polyimide is a polyimide obtained by heating and imidizing a polyimide precursor obtained by polymerizing aromatic teracarboxylic dianhydride and aromatic diamine in an organic polar solvent. In addition, the polyimide contains heat conductive fine particles.

  The present invention is a metal deposited film in which the metal layer is formed by thermal spraying, and has a thickness of 20 μm to 300 μm.

  In addition, the present invention is characterized in that the release layer is at least one layer selected from a fluororesin layer, a silicone rubber layer, and a fluororubber layer. The release layer may be a fluororesin layer or a laminate in which a silicone rubber layer is formed on the inner layer and a fluororesin layer is laminated on the surface thereof.

  Next, in the method for manufacturing a fixing belt of the present invention, a polyimide precursor solution is cast on the surface of a cylindrical mold to form a polyimide precursor solution film, and the precursor solution film is at least strength as a tubular material. Is heated to a state where it can be maintained to produce a polyimide tubular product, and then a metal deposition film is formed on the outer surface of the polyimide tubular product by a thermal spraying method, and a release layer is formed on the outer surface of the metal deposition coating, Then, it heats and each layer is integrated, It is characterized by the above-mentioned.

  A metal deposited film is formed on the outer surface of the polyimide tubular body by a thermal spraying method when the imidization ratio of the polyimide tubular body is 50 to 90%.

  Since the fixing belt of the present invention has a structure in which the base layer is made of a flexible polyimide and has a metal deposited film layer formed by thermal spraying on the outer surface thereof, it is flexible even with a small diameter, and has a metal layer. Excellent mechanical properties and can eliminate fixing belt damage caused by paper jams. In addition, since polyimide includes heat conductive fine particles and a metal layer is formed on the outer surface thereof, a fixing belt having excellent heat conductivity can be provided. Further, according to the fixing belt manufacturing method of the present invention, since the molten metal collides with the polyimide layer in the form of fine particles, the adhesive force between the polyimide layer and the metal layer is strong, and the release layer is a metal deposited film. Since it is molded in a throwing structure on the outer surface of the layer, it is possible to provide a fixing belt having high durability between the metal layer and the release layer and excellent durability.

  Next, an embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view of an example of a fixing belt of the present invention. The fixing belt of the present invention has a configuration in which a metal deposition coating 2 formed by thermal spraying is formed on the outer surface of a polyimide tubular body 1 serving as a base material, and a release layer 3 is formed on the outer surface thereof. The fixing belt of the present invention has a structure in which a polyimide layer and a metal layer are laminated. The polyimide layer takes advantage of the properties of the plastic material such as flexibility and insulation, and the metal layer has thermal conductivity and mechanical properties. It is a fixing belt that has the characteristics that each characteristic is combined. In the present invention, the metal layer is preferably a metal deposited film formed by thermal spraying. The metal layer formed by thermal spraying, the molten and finely divided metal collides with the outer surface of the polyimide tube or the surface of the metal coating that has already been formed, spreads and adheres rapidly along it, and deposits as a coating. This is because, since it is formed, it is different from a dense crystal structure manufactured metallurgically, so that a flexible metal layer can be obtained.

  Further, the metal material to be molded by the thermal spraying method is not particularly limited, and stainless steel, aluminum, zinc, aluminum bronze, tin and the like can be used alone or an alloy thereof. The metal coating is formed by melting the metal by an arc spraying method, plasma spraying method, or the like, and colliding metal fine particles with the surface of the polyimide layer to form a coating. Therefore, the melting point of the metal material to be sprayed is 1000 ° C. or less. It is preferable.

  When a metal material having a melting point of 1000 ° C. or higher is sprayed on the polyimide layer, the surface roughness of the metal deposited film becomes rough, which is not preferable. Since the deposited metal film formed by thermal spraying is formed by collision of the fine metal particles once melted, the surface is formed in a complicated uneven state, but the surface roughness is a measured value Rz according to JIS-B0601, 5 to 5. A range of 10 μm is preferred. When the release layer is within this range, when the release layer is formed on the surface of the metal layer, the release layer material can be thrown into the concave portion, and the adhesive force between the metal layer and the release layer can be enhanced. FIG. 3 is a photomicrograph of the deposited metal film.

  The thermal spraying method is preferably an arc spraying method in which a metal wire is melted by arc discharge, the molten metal is atomized by compressed air, and sprayed onto the polyimide layer to form a film. This is because the metal material can be sufficiently melted, a fine metal deposition film can be formed on the surface of the polyimide layer, and even a small member such as a fixing belt can be sprayed with a relatively compact equipment. .

  In the fixing belt of the present invention, the polyimide as a base material is a polyimide obtained by imidization by heating a polyimide precursor solution obtained by polymerizing aromatic tetracarboxylic dianhydride and aromatic diamine in an organic polar solvent. preferable. When the polyimide precursor is in the form of a solution, it is possible to uniformly disperse the heat conductive fine particles, etc., and the viscosity and solid content concentration of the polyimide precursor solution can be adjusted. This is because it can be set with high accuracy.

  The thickness of the polyimide tubular product is preferably in the range of 5 μm to 70 μm, more preferably in the range of 10 μm to 50 μm. This is because if the thickness of the polyimide layer is within the above range, a fixing belt having excellent flexibility and thermal conductivity can be obtained.

  The polyimide precursor solution can be obtained by reacting approximately equimolar amounts of an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic polar solvent. Representative examples of the aromatic tetracarboxylic dianhydride include 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 2,3,3 ′, 4- Biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8- Naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) propane dianhydride, perylene-3,4, 9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, and the like.

  Representative examples of the aromatic diamine include 4,4'-diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 1,5-diaminonaphthalene, 3,3'-dichlorobenzidine, 3,3'- Diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-biphenyldiamine, 4,4'-diaminodiphenyl sulfide-3,3'-diaminodiphenylsulfone, benzidine, 3,3 ' -Dimethylbenzidine, 4,4'-diaminophenylsulfone, 4,4'-diaminodiphenylpropane, m-xylylenediamine, hexamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine and the like.

  These aromatic tetracarboxylic dianhydrides and aromatic diamines can be used alone or in combination. It is also possible to complete the polyimide precursor solution and use it by mixing these precursor solutions.

  Examples of the organic polar solvent for reacting the aromatic tetracarboxylic dianhydride and the aromatic diamine include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide. N, N-diethylacetamide, dimethyl sulfoxide, hexamethyl phosphortriamide, pyridine, dimethyltetramethylene sulfone, tetramethylene sulfone, propylene carbonate, γ-butyrolactone, etc., and these solvents are used alone or in combination. It is preferable.

  The polyimide precursor solution is obtained by reacting the aromatic tetracarboxylic dianhydride and the aromatic diamine in an organic polar solvent, usually at 90 ° C. or less, and the solid content concentration in the solvent is produced. Although it can be set according to the specifications and processing conditions of the polyimide tubular product to be made, it is 10 to 50% by weight.

  In addition, when aromatic tetracarboxylic dianhydride and aromatic diamine are reacted in an organic polar solvent, the viscosity of the solution increases depending on the polymerization conditions. Can do. It is usually used at a viscosity of 1 to 5000 poise depending on manufacturing conditions and working conditions. More preferably, it is 700-1500 poise. This is because a tube having a uniform thickness can be produced even when the polyimide precursor solution is applied to the surface of the cylindrical mold within this range.

  Moreover, in this invention, it is preferable that the said polyimide layer contains heat conductive fine particle. This is because the thermal conductivity can be further improved as a fixing belt. The thermally conductive fine particles contained in the polyimide are preferably insulating inorganic fine particles. For example, boron nitride, alumina, silicon carbide, potassium titanate, aluminum nitride, titanium oxide, carbon nanofibers, and the like are preferable materials. Or can be used in combination. Among these, boron nitride, alumina, silicon carbide, and aluminum nitride are more preferable heat conductive fine particles.

  The content of the heat conductive fine particles is usually 10 to 50% by weight, preferably 15 to 40% by weight. The average particle diameter of the heat conductive fine particles is in the range of 0.01 to 10 μm, preferably in the range of 0.1 to 5 μm.

  In the present invention, it is preferable that the metal layer is a metal deposited film formed by thermal spraying and has a thickness of 20 μm or more and 300 μm or less. When the thickness of the metal deposited film is 20 μm or less, it is difficult to obtain mechanical characteristics and thermal conductivity characteristics, and when the thickness is 300 μm or more, flexibility as a fixing belt cannot be obtained. A more preferred thickness is in the range of 50 μm to 200 μm.

  In the present invention, the release layer is preferably at least one layer selected from a fluororesin layer, a silicone rubber layer, and a fluororubber layer. A fluororesin is a more preferable release layer material, such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-hexafluoro. It is preferable to use a propylene copolymer (FEP) alone or as a mixture thereof.

  As a method for forming the release layer on the outer surface of the metal layer, a dipping method, a spray method, a powder coating method, or the like can be used. In the present invention, it is preferable that an unfired fluororesin dispersion is applied by a dipping method and then heated to a temperature equal to or higher than the melting point of the fluororesin to be fired to form a release layer. When it is a fluororesin dispersion, it can be applied in a state where the concave surface of the metal deposit film is impregnated, and then it can be molded into a throwing structure by firing the fluororesin, thereby improving the adhesive force. Because. Moreover, the adhesive force can be further improved by using an adhesion assistant such as a primer before applying the release layer.

  In the present invention, the release layer is preferably a fluororesin layer or a laminate in which a silicone rubber layer is formed on the inner layer and a fluororesin layer is laminated on the surface. Full-color printers and copiers use four basic toner colors of red, blue, yellow, and black to form a color image. To increase the color and hue of intermediate colors, the nip between the fixing belt and the pressure roll is used. It is necessary to sufficiently melt and mix four colors of toner on the surface. Therefore, it is preferable that the width of the nip surface where the fixing belt and the pressure roll come into contact is wide, and in order to widen the nip surface, an elastic layer such as silicone rubber is preferably laminated. The silicone rubber is preferably liquid, and commercially available products such as room temperature curable silicone rubber (silicone RTV) can be used. In addition, it is preferable to mix iron oxide, zinc oxide, carbon fiber, metal filler, and the like in these elastic layers in order to improve thermal conductivity.

The elastic layer is laminated between the metal layer of the fixing belt and the fluororesin release layer, and the rubber hardness of the elastic layer is preferably in the range of 3 to 50 degrees in terms of JIS A hardness, and in the range of 5 to 40 degrees. More preferred. In order to wrap and mix the color toner image melted at the time of heat fixing, it is preferable that the hardness of the elastic layer is low. However, when it is 3 degrees or less, the low molecular component in the silicone rubber causes the adhesion between the release layer and the metal layer. This is not preferable because it hinders or precipitates on the surface of the release layer, leading to a decrease in the fixed image. On the other hand, if the hardness of the elastic layer exceeds 50 degrees, the flexibility is lowered and a good quality image cannot be obtained, which is not preferable. The thickness of the silicone rubber layer is preferably in the range of 30 μm to 500 μm. More preferably, it is in the range of 100 to 300 μm from the effect of wrapping and mixing toner images in synergy with the rubber hardness characteristics.

  Next, in the method for manufacturing a fixing belt of the present invention, a polyimide precursor solution is cast on the surface of a cylindrical mold to form a polyimide precursor solution film, and the precursor solution film is at least strength as a tubular material. Is heated to a state where it can be maintained to produce a polyimide tubular product, and then a metal deposition film is formed on the outer surface of the polyimide tubular product by a thermal spraying method, and a release layer is formed on the outer surface of the metal deposition coating, Then, it is a manufacturing method characterized by heating and integrating each layer.

  First, the polyimide precursor solution is cast-molded on the surface of a cylindrical mold, and a method for forming a polyimide tubular material is the method of Patent Document 1 proposed by the present applicants or Patent Publication No. 2004-291367. Can be manufactured. When a metal layer is formed by a thermal spraying method after forming a polyimide tubular product, the polyimide layer is sprayed with metal on the surface of the polyimide semi-cured tubular product until the imidization reaction is completed. After the release layer is formed on the outer surface of the layer, it is preferable to heat and complete the imidization reaction completion treatment and the release layer firing treatment simultaneously.

  When metal is sprayed onto the surface of the polyimide semi-cured tubular product until the imidization reaction is completed, the metal surface collides in a heated state on the polyimide surface, and is formed in a state where it is stuck into the polyimide layer, and then polyimide This is because the imidization reaction is completed by reheating and the polyimide layer contracts to obtain a strong adhesive force.

  In the production method of the present invention, it is preferable to form a metal deposited film by spraying metal at a stage where the imidization ratio of the polyimide semi-cured tubular product is 50 to 90%. If the polyimide imidation rate is 50% or less, the polyimide layer may be destroyed during thermal spraying, and if it exceeds 90%, metal fine particles formed by thermal spraying are placed on the polyimide layer surface. In this case, sufficient adhesive strength cannot be obtained. In addition, even when the polyimide tube is imidated, or the polyimide has an imidization ratio of 90% or more, the surface of the polyimide layer is roughened by sandpaper or blasting to provide adhesion. Can be improved. Moreover, after forming a primer layer such as an epoxy resin or a polyamideimide resin in advance on the surface of the polyimide layer, the adhesion can be improved by forming a metal layer by thermal spraying.

  Hereinafter, the fixing belt of the present invention and the manufacturing method thereof will be described in detail based on examples. The imidation ratio of the present invention was measured using a Fourier transform infrared spectrophotometer (FTIR) (“IR-21” manufactured by Shimadzu Corporation).

(1) Preparation of polyimide tubular material An aluminum mold having an outer diameter of 18 mm and a length of 500 mm is prepared, and a silicon oxide coating agent is coated on the mold surface by a dipping method, heated and baked, and coated with a silicon oxide film A mold was used. The surface roughness Rz of the mold was 0.5 μm. Next, a precursor solution in which boron nitride (BN) (manufactured by Mitsui Chemicals) was uniformly mixed with 27% by weight with respect to the solid content of the polyimide precursor in a 900 poise polyimide precursor solution (“RC5063 PyreML Varnish” manufactured by IST). Prepared.

  The mold is immersed in the boron nitride mixed polyimide precursor solution up to 400 mm, and after applying the polyimide precursor solution, a ring-shaped die having an inner diameter of 18.8 mm is inserted from above the mold, The polyimide precursor solution was cast on the surface of the mold with a thickness of 400 μm. Then, as a first imidization treatment, it is placed in an oven at 120 ° C., dried for 30 minutes, heated to 200 ° C. for 20 minutes, held at that temperature for 20 minutes, cooled to room temperature, An 18 mm semi-cured polyimide tube was prepared. The imidation ratio of this polyimide was 78%.

(2) Metal spraying process The semi-cured polyimide tubular material is attached at a distance of 150 mm from the spraying port, and while rotating at a speed of 343 rpm, an arc spraying machine ("PC250iDEX" manufactured by Arctechno) is used to arc discharge the zinc wire and spraying. Then, a zinc deposit film having a thickness of about 50 μm was formed to obtain a “polyimide / zinc layer tubular product”. The average surface roughness Rz of the surface of this deposited film was 6.5 μm.

(3) Preparation of release layer The polyimide polyimide zinc tubular article having a zinc deposit coating formed on the outer surface of the polyimide tubular article is immersed in a fluororesin primer solution (DuPont: trade name “Teflon 855-003”). Coated to a thickness of about 4 μm. Then, it dried for 20 minutes at the temperature of 180 degree C, and cooled to normal temperature again.

  Next, it was dipped in a PTFE dispersion (manufactured by DuPont: trade name “Teflon 855-510”), pulled up, and coated to a thickness of 15 μm. Then, after drying at 200 ° C. for 10 minutes, the temperature is raised to 400 ° C. and heated for 20 minutes, and after firing the PTFE resin, the mold and the tubular material are separated, and a zinc layer is formed on the outer surface of the polyimide tubular material, and A fixing belt composed of a fluororesin release layer was produced.

  As a result of inserting the fixing belt into the printer having the fixing device shown in FIG. 2 and printing at a speed of 36 sheets per minute, a good image and durability can be obtained, and no problem occurs in the 50,000 sheet passing test. was gotten.

  The polyimide precursor solution was cast on the surface of the mold under the conditions of Example 1 to perform a primary imidization treatment, and then continued as a secondary imidization treatment from 200 ° C. to 400 ° C. to 40 ° C. The temperature was raised in minutes, and the polyimide tubular product was produced by maintaining the temperature for 20 minutes to complete the imidization reaction. Thereafter, the surface of the polyimide tubular product was blasted. The average surface roughness Rz after blasting was 4.8 μm.

  Thereafter, in the same manner as in Example 1, a zinc spray treatment and a release layer were formed to produce a fixing belt. As a result of inserting this fixing belt into a printer having the fixing device shown in FIG. 2 and printing at a speed of 36 sheets per minute, good images and durability were obtained, and no problem was found in a 50,000 sheet passing test. Obtained.

  A fixing belt was produced in the same manner as in Example 1 except that the metal spraying process in Example 1 was changed to the following method. In the metal spraying method, a semi-cured polyimide tube is fixed at a distance of 200 mm from the spraying port, and an aluminum bronze wire is arc-discharged using an arc spraying machine ("PC250iDEX" manufactured by Arctechno) while rotating at a speed of 343 RPM. Thermal spraying was performed to form an aluminum bronze deposited film having a thickness of about 60 μm, and a “polyimide / aluminum bronze layer tubular product” was obtained. The average surface roughness Rz of the surface of this deposited film was 8.2 μm. Further, a release layer was formed on the outer surface of the “polyimide / aluminum bronze layer tubular product” under the same conditions as in Example 1 to prepare a fixing bell. As a result of inserting this fixing belt into a printer having the fixing device shown in FIG. 2 and printing at a speed of 36 sheets per minute, good images and durability were obtained, and no problem was found in a 50,000 sheet passing test. Obtained.

  The “polyimide / aluminum bronze layer tubular product” having a metal layer sprayed with aluminum bronze on the outer surface of the polyimide tubular product obtained in Example 3 was used. Uniformly apply with a brush using a primer (GE Toshiba Silicone “XP-81-405”) solution A and B2 solution mixed at a ratio of 1: 1 in advance to the outer surface of the “polyimide / aluminum bronze layer tubular product”. After drying at room temperature (23 ° C.) for 20 minutes, it was placed in an oven at 150 ° C. and dried for 20 minutes.

  Thereafter, a liquid silicone rubber in which two liquids of liquid silicone rubber (“XE15-B9055” manufactured by GE Toshiba Silicone) A and B are mixed in a ratio of 1: 1 in advance is applied to the surface of the primer layer, and then passed through a die. Molded to a thickness of 190 μm. Thereafter, primary vulcanization is performed at a temperature of 150 ° C. for 20 minutes, secondary vulcanization is performed at a temperature of 220 ° C. for 60 minutes, and a silicone rubber having a thickness of 190 μm is formed on the outer surface of the “polyimide / aluminum bronze layer tubular product”. A molded three-layer tubular product was obtained. The hardness of the silicone rubber test piece produced under the same conditions was 32 degrees.

  Furthermore, the outer surface of the three-layered tube was lightly roughened with # 500 sandpaper, and the surface was washed with alcohol. Next, a liquid primer (“PR-990CL” manufactured by Mitsui DuPont Fluorochemicals) was applied to the silicone rubber surface and dried at room temperature for 10 minutes. Thereafter, the three-layered tubular material is dipped in a PFA dispersion (“PFA920HP plus ENA-162-8” manufactured by DuPont) adjusted to a viscosity of 200 centipoise, pulled up at a predetermined speed, and 15 μm in final thickness. After coating at room temperature for 30 minutes, it was placed in an oven at 330 ° C. and baked for 15 minutes to obtain the intended fixing belt.

  This composite belt had an inner diameter of 18 mm, a polyimide layer of 40 μm, a silicone rubber layer of 190 μm, a PFA resin layer of 15 μm, and a total thickness of about 245 μm. The surface roughness Rz of the release layer of this fixing belt was 1.5 μm. This fixing belt is mounted on a tandem type color printer having the fixing mechanism shown in FIG. 2, and a sheet passing fixing is performed at a speed of 4 sheets / min. As a result, a good image of 20,000 sheets is obtained and a fixing belt for a full color image is obtained. As the most suitable.

(Comparative Example 1)
Using the polyimide precursor solution of Example 1 and boron nitride, the boron nitride mixed polyimide precursor solution was prepared by changing the mixing amount of boron nitride to 32 wt%, and the thickness after completion of imidization was 70 μm. A semi-cured polyimide tube was prepared under the same conditions as in Example 1. Thereafter, the metal spraying step is omitted, and the outer surface of the semi-cured polyimide tubular material is directly coated with the same fluororesin primer and PTFE dispersion as in Example 1 and then heated to 400 ° C. to imidize the polyimide. Completion and PTFE resin firing were performed simultaneously to prepare a two-layer fixing belt comprising a polyimide layer and a fluororesin release layer. The fixing belt was mounted on the same printer as in Example 1 and a fixing test was performed. As a result, the fixing belt did not buckle or break, but the thermal conductivity was poor in the continuous paper passing test, and the paper after fixing. When rubbed over, stains due to insufficient fixing occurred.

(Comparative Example 2)
As a first imidization treatment of the polyimide tubular product produced in Example 1, a semi-cured polyimide tubular product was produced by heat treatment at a temperature of 150 ° C. for 40 minutes. The imidation ratio of this polyimide film was 37%, and when metal spraying was performed in the same manner as in Example 1, the polyimide layer was destroyed.

  The fixing belt of the present invention is a fixing belt that has thermal conductivity, flexibility, and durability as a fixing belt for monochrome or full-color images, and can satisfy the conditions for speeding up, downsizing, and weight reduction of the image forming apparatus. .

2 is a schematic cross-sectional view of a fixing belt of the present invention. FIG. It is a schematic sectional drawing of the fixing mechanism of a belt fixing system. It is a microscope picture of a metal deposit film.

Explanation of symbols

1: Polyimide layer 2: Metal layer 3: Release layer

Claims (8)

  A fixing belt in which a metal layer is formed on the outer surface of a tubular material made of polyimide and a release layer is formed on the outer surface of the metal layer, and the metal layer is formed of a metal deposit film formed by thermal spraying. A fixing belt characterized by that.   2. The polyimide according to claim 1, wherein the polyimide is a polyimide obtained by heating and imidizing a polyimide precursor obtained by polymerizing an aromatic teracarboxylic dianhydride and an aromatic diamine in an organic polar solvent. Fixing belt   The fixing belt according to claim 1, wherein the polyimide includes heat conductive fine particles.   The fixing belt according to claim 1, wherein the metal layer has a thickness of 20 μm to 300 μm.   The fixing belt according to claim 1, wherein the release layer is at least one layer selected from a fluororesin layer, a silicone rubber layer, and a fluororubber layer.   The fixing belt according to claim 1, wherein the release layer is a fluororesin layer or a laminate in which a silicone rubber layer is formed on an inner layer and a fluororesin layer is laminated on the surface thereof.   A polyimide precursor solution is cast on the surface of a cylindrical mold to form a polyimide precursor solution coating, and the precursor solution coating is heated to a state where at least the strength as a tubular product can be maintained to produce a polyimide tubular product. Then, a metal deposition film is formed on the outer surface of the polyimide tubular article by a thermal spraying method, a release layer is formed on the outer surface of the metal deposition film, and then the layers are integrated by heating. A method for manufacturing a fixing belt. 8. The fixing belt manufacturing method according to claim 7, wherein a metal deposition film is formed on the outer surface of the polyimide tubular body by a thermal spraying method when the imidization ratio of the polyimide tubular body is 50 to 90%. Method.

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