JP2013061383A - Tubular member, endless belt, fixing device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tubular member that has excellent wear resistance and mold releasability, an endless belt, a fixing device including the endless belt, and an image forming apparatus.SOLUTION: Provided are a tubular member that has a surface layer including a multi-branched polymer compound containing fluorine atoms, and polyimide; an endless belt that is configured by including the tubular member; a fixing device including the endless belt; and an image forming apparatus.

Description

  The present invention relates to a tubular member, an endless belt, a fixing device, and an image forming apparatus.

  In an image forming apparatus such as a copying machine or a printer using an electrophotographic system, an unfixed toner image formed on a recording medium such as recording paper is fixed by a fixing device to form an image. As a fixing device used in such an image forming apparatus, a rotating fixing roll whose surface is elastically deformed and an addi- tional capable of running in contact with the fixing roll in order to cope with an increase in the speed of the image forming apparatus. A pressure belt and a pressure pad disposed in a non-rotating state inside the pressure belt are provided, and the pressure belt is pressed against the fixing roll so that a contact surface with the fixing roll is formed by the pressure pad. And a belt nip system in which a belt nip is provided between the pressure belt and the fixing roll so that the recording medium can pass therethrough, and the outlet side of the recording medium is locally elastically deformed on the surface of the fixing roll. There is a technique related to a fixing device called (see, for example, Patent Document 1).

  As a pressure belt of such a belt nip type fixing device, polyimide having excellent strength, dimensional stability, wear resistance, heat resistance, and the like is used. Further, a release layer is usually disposed on the surface of the pressure belt or fixing belt for the electrophotographic system in order to ensure releasability from the toner. As the release layer, fluororubber, fluororesin, or the like is used, and fluororesin is often used because of good release properties.

  Also, endless belts intended to combine wear resistance and releasability, and fluororesin particles are actively used by mixing polyimide precursors with excellent wear resistance and fluororesin particles, followed by firing and imidization. In particular, an endless belt (see, for example, Patent Documents 2 and 3) that aims to have both wear resistance and releasability by being deposited and unevenly distributed on the belt surface has been proposed.

  Furthermore, an endless belt mainly composed of fluorinated polyimide has been proposed for the purpose of maintaining release properties in a polyimide having excellent wear resistance (see, for example, Patent Document 4).

Japanese Patent No. 3298354 Japanese Patent Laid-Open No. 11-156971 JP 2006-256323 A Japanese Patent No. 3069041

  An object of the present invention is to provide a tubular member having excellent wear resistance and releasability, an endless belt, a fixing device including the endless belt, and an image forming apparatus.

  The invention according to claim 1 is a tubular member having a surface layer containing a hyperbranched polymer compound containing fluorine atoms and polyimide.

  The invention according to claim 2 is the tubular member according to claim 1, wherein the fluorine atom content measured on the surface of the surface layer by X-ray photoelectron spectroscopy (XPS) is in the range of 1% to 90%. is there.

  The invention according to claim 3 is an endless belt configured to include the tubular member according to claim 1 or 2.

  The invention according to claim 4 includes a pair of fixing units including a heating member and a pressure member pressed against the heating member, and an unfixed toner in a nip region formed by the heating member and the pressure member. 4. The fixing device according to claim 3, wherein an image-holding recording medium is passed, the unfixed toner image is fixed by heat and pressure, and at least one of the heating member and the pressure member is an endless belt according to claim 3. .

  The invention according to claim 5 is an image forming apparatus comprising at least a toner image forming unit for holding an unfixed toner image on a recording medium and the fixing device according to claim 4.

  According to the first aspect of the present invention, there is provided a tubular member that is superior in wear resistance and releasability as compared with a case where the surface layer containing a multi-branched polymer compound containing fluorine atoms and polyimide is not provided. The

  According to the invention which concerns on Claim 2, compared with the case where the said fluorine atom content rate is not the range of 1% or more and 90% or less, the tubular member excellent in abrasion resistance or mold release property is provided.

  According to the invention of claim 3, an endless belt is provided that is superior in wear resistance and releasability as compared with a case where the surface layer containing a multi-branched polymer compound containing fluorine atoms and polyimide is not provided. The

  According to the invention of claim 4, compared to the case where at least one of the heating member and the pressure member does not have a surface layer containing a multi-branched polymer compound containing fluorine atoms and polyimide, the heating member and the heating member are added. A fixing device having excellent wear resistance and releasability of at least one of the pressure members is provided.

  According to the invention of claim 5, at least one of the heating member and the pressure member of the fixing device is fixed as compared with the case where the surface layer containing the multi-branched polymer compound containing fluorine atoms and polyimide is not included. Provided is an image forming apparatus excellent in wear resistance and releasability of at least one of a heating member and a pressure member of the apparatus.

FIG. 3 is a side sectional view illustrating an example of a configuration of a fixing device according to an embodiment of the present invention. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

<Tubular member>
A tubular member according to an embodiment of the present invention has a surface layer containing a multi-branched polymer compound containing fluorine atoms and polyimide. The tubular member according to this embodiment may have a single-layer configuration of the surface layer, or may have a configuration of two or more layers having the surface layer. A multi-branched polymer compound containing a fluorine atom becomes a spherical polymer having a particle size on the order of nm, hardly aggregates even when dispersed in polyimide, and almost forms a sea-island structure with the spherical polymer and polyimide. Therefore, the release property of the surface layer is improved. Therefore, a tubular member having excellent wear resistance and releasability can be obtained.

  For example, the tubular member according to this embodiment is obtained by mixing a polybranched polymer compound containing a fluorine atom into a polyamic acid composition containing a polyamic acid that is a polyimide precursor, and then mixing the polybranched polymer-containing polyamic acid composition. It is obtained by preparing, applying to a core body such as a cylindrical mold, and imidizing by heating.

  The polyamic acid composition may be produced, for example, by synthesizing a substantially equal molar amount of a diamine compound and tetracarboxylic dianhydride in an organic polar solvent. There is no restriction | limiting in particular as a diamine compound and tetracarboxylic dianhydride used for manufacture of a polyamic acid, You may use any compound of an aromatic type and an aliphatic type.

  Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, and 3,3 ′, 4,4′-biphenyl. Sulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′- Biphenyl ether tetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3 ′, 4,4′-tetraphenylsilane tetracarboxylic dianhydride, 1 , 2,3,4-furantetracarboxylic dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dicarboxyl) Noxi) diphenylsulfone dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidenediphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (Triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4′-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4′-diphenylmethane dianhydride, and the like.

  Aliphatic tetracarboxylic dianhydrides include butane tetracarboxylic dianhydride, 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane. Tetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxynorbornane-2- Acetic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofuranyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride Products, aliphatic or alicyclic tetracarboxylic dianhydrides such as bicyclo [2,2,2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride; 1 3,3a, 4,5,9b-Hexahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b -Hexahydro-5-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b 2-aliphatic tetracarboxylic acid having an aromatic ring such as hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione An anhydride etc. are mentioned.

  As tetracarboxylic dianhydride, aromatic tetracarboxylic dianhydride is preferable, and pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3, 3 ′, 4,4′-biphenylsulfonetetracarboxylic dianhydride is more preferred. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  The diamine compound is not particularly limited as long as it is a diamine compound having two amino groups in the molecular structure. Examples of the diamine compound include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfide. 4,4′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4′-diaminobiphenyl, 5-amino-1- (4′-aminophenyl) -1,3,3 -Trimethylindane, 6-amino-1- (4'-aminophenyl) -1,3,3-trimethylindane, 4,4'-diaminobenzanilide, 3,5-diamino-3'-trifluoromethylbenzanilide 3,5-diamino-4′-trifluoromethylbenzanilide, 3,4′-diaminodiph Nyl ether, 2,7-diaminofluorene, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4′-methylene-bis (2-chloroaniline), 2,2 ′, 5,5′-tetra Chloro-4,4′-diaminobiphenyl, 2,2′-dichloro-4,4′-diamino-5,5′-dimethoxybiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 4,4 '-Diamino-2,2'-bis (trifluoromethyl) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl ] Hexafluoropropane, 1,4-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) -biphenyl, 1,3'-bis (4-amino) Phenoxy) benzene, 9,9-bis (4-aminophenyl) fluorene, 4,4 ′-(p-phenyleneisopropylidene) bisaniline, 4,4 ′-(m-phenyleneisopropylidene) bisaniline, 2,2′- Bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4′-bis [4- (4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl, etc. Aromatic diamines; aromatic diamines having two amino groups bonded to an aromatic ring such as diaminotetraphenylthiophene and heteroatoms other than nitrogen atoms of the amino groups; 1,1-metaxylylenediamine, 1,3 -Propanediamine, tetramethylenediamine, pentamethylenediamine, octamethylenediamine, Namethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylenediethyleneethylene, tricyclo [6, 2,1,02.7] -undecylenedimethyldiamine, aliphatic diamines such as 4,4′-methylenebis (cyclohexylamine), and alicyclic diamines.

  As the diamine compound, aromatic diamines are preferable, and p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenyl sulfone. Is more preferable. These diamine compounds may be used alone or in combination of two or more.

  The polyamic acid is preferably a product obtained by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine from the viewpoint of the strength of the molded article.

  The organic polar solvent used in the polyamic acid production reaction is not particularly limited as long as it dissolves polyamic acid and partially imidized polyamic acid. Examples of the organic polar solvent include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, N, N-dimethylacetamide, and N, N-diethyl. Acetamide solvents such as acetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-cresol, m-cresol or p-cresol, xylenol, halogenated phenol, catechol, etc. Phenol solvents such as tetrahydrofuran, dioxane and dioxolane, alcohol solvents such as methanol, ethanol and butanol, cellosolve solvents such as butyl cellosolve or hexamethylphosphoramide, γ-butyl Rorakuton and the like, it is preferred to use these alone or as a mixture, further xylene, may be used aromatic hydrocarbons such as toluene. The polyamic acid composition preferably contains an organic polar solvent so that the solid content is 5% by mass or more and 30% by mass or less.

  Examples of the hyperbranched polymer compound containing a fluorine atom include a hyperbranched polymer containing a fluorine atom, a dendrimer containing a fluorine atom, and specifically, a compound represented by the following structural formula (1) And a copolymer of a compound having an acrylic group or a methacrylic group.

（式中、Ｒ_１は、水素原子またはメチル基を表し、Ｒ_２は、水素原子またはフッ素原子を表し、Ｙは、−（ＣＦ_２）_ｎ−を表す。ｎは１以上２０以下の整数を表す。）

(In the formula, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom or a fluorine atom, and Y represents — (CF ₂ ) _n —. N represents an integer of 1-20. Represents.)

In the structural formula (1), R ₁ is preferably a hydrogen atom or a methyl group, and R ₂ and Y are a fluoroalkyl group in which R ₂ is a fluorine atom and Y is represented by — (CF ₂ ) _n —. Preferably, n is 1 or more and 20 or less.

  Examples of the compound having an acrylic group or a methacryl group include acrylic acid, methacrylic acid, and ethylene glycol dimethacrylate.

  The polymerization ratio of the compound represented by the structural formula (1) and the compound having an acryl group or a methacryl group is, for example, 0.05 to 200 in terms of molar ratio.

  The number average molecular weight (Mn) of the multi-branched polymer compound containing a fluorine atom is preferably in the range of 100 or more and 100,000 or less. When the number average molecular weight is less than 100, the effect of modifying the releasability by fluorine atoms may not be sufficiently obtained. When the number average molecular weight exceeds 100,000, the dispersibility of the multi-branched polymer compound in the polyimide decreases. However, there may be a case where substantially uniform releasability cannot be obtained.

  The fluorine atom content measured by X-ray photoelectron spectroscopy (hereinafter also referred to as XPS) of the surface layer of the tubular member according to this embodiment is preferably in the range of 1% to 90%, A range of 1% to 75% is more preferable, and a range of 4% to 70% is more preferable. If the fluorine atom content is less than 1%, the releasability may not be sufficiently obtained, and if it exceeds 90%, the wear resistance of the surface may be lowered.

  In addition, the fluorine atom content rate on the surface of the surface layer is specifically measured by using “VG ESCALAB-220i” as an XPS measurement device, and using a monochromatic AlKα ray as an X-ray source. The measurement is performed for fluorine atoms by setting the voltage to 10 kV and the emission current to 20 mV. The analysis region is about 1 mmφ, and the detection depth is 3 nm. Then, the C1s spectrum is measured for the fluorine atom, the number of elements is obtained based on the spectrum of the fluorine atom, and the fluorine atom content with respect to the total atomic weight of the surface layer is calculated.

<Method for producing tubular member>
Next, the manufacturing method of the tubular member concerning this embodiment is demonstrated. First, a polyamic acid composition containing the polyamic acid is prepared according to a known method (polyamic acid composition preparation step). A multi-branched polymer compound containing fluorine atoms is dispersed in the polyamic acid composition (dispersing step). At this time, the content of the multi-branched polymer compound containing a fluorine atom is preferably in the range of 1% by mass to 90% by mass with respect to the solid content of the polyamic acid composition, and is preferably 5% by mass to 85%. The range is more preferably in the range of mass% or less, and further preferably in the range of 10 mass% to 80 mass%.

  Next, using a composition obtained by stirring and defoaming a polybranched polymer-containing polyamic acid composition containing a multi-branched polymer compound containing fluorine atoms, according to a conventional method, for example, made of polyimide Manufacture endless belts. As a method for producing this polyimide endless belt, for example, first, a multi-branched polymer-containing polyamic acid composition is applied to the outer peripheral surface or inner peripheral surface of a cylindrical core (application step). Examples of the application method include the following, but are not limited thereto.

  Examples of the method of applying to the outer peripheral surface of the cylindrical core body include, for example, a method of applying the core body to the outer peripheral surface of the core body by immersing the core body in the multi-branched polymer-containing polyamic acid composition and then pulling it up. While rotating the core in a horizontal direction with respect to its central axis, the polyamic acid composition containing a multi-branched polymer is applied to the surface in a spiral manner, and the coating film is smoothed with a blade or the like. And the like. As a method of applying to the inner peripheral surface of a cylindrical core or the like, for example, a method of applying to the inner peripheral surface of the core by immersing the core in a polybranched polymer-containing polyamic acid composition and then pulling it up , A method of supplying a multi-branched polymer-containing polyamic acid composition near one end of a cylindrical body, and running a bullet-shaped or spherical traveling body along the inner peripheral surface of the core. It is done. These coating methods may be appropriately selected depending on the situation.

  The material of the core is not particularly limited as long as it can withstand the drying and heating temperatures described below, but metals such as aluminum, nickel, and stainless steel are preferable. Among these, aluminum is particularly preferable from the viewpoint that the coefficient of thermal expansion is large. The surface of the core body may be coated with a metal such as chromium or nickel, or coated with a resin such as a fluorine resin or a silicone resin.

  The surface of the core is preferably roughened so that the surface roughness Ra is about 0.2 μm to 2 μm. There are roughening methods such as blasting, cutting, sandpapering, etc., but in order to make the inner surface of the endless belt have a spherical surface with good slidability and a minute convex and concave shape, The surface of the body is preferably subjected to blasting using spherical particles.

  Subsequently, a step of drying the applied polyamic acid coating film in a range of, for example, 40 ° C. or higher and 130 ° C. or lower is performed (drying step). At this time, since the polyamic acid coating film is affected by gravity or the like, dripping easily occurs. In that case, for example, the coated cylindrical body or the like may be horizontally left in the axial direction and allowed to stand while being rotated at about 10 rpm to about 60 rpm. When coating is performed while rotating the core body, it is preferable that the core body is continuously rotated from the spin coating process.

  In the drying step, the fluorine atom of the multi-branched polymer compound containing fluorine atoms in the polybranched polymer-containing polyamic acid composition is moved from the organic polar solvent to the coating film surface layer portion which is a gas boundary surface which is a hydrophobic atmosphere, In order to make the coating surface layer portion highly hydrophobic, the gas atmosphere is preferably an inert gas atmosphere. For example, nitrogen, argon, or the like is preferably used as the inert gas. Furthermore, in order to prevent the surface layer portion of the coating film from becoming a hydrophilic atmosphere due to the volatilized organic polar solvent, it is more preferable to continue intake and exhaust using an inert gas having a purity of 80% or more and 100% or less in the drying step.

  Note that the leaving step may be performed after the coating step and before the drying step. The leaving step is a step of leaving the polyamic acid coating film at 15 ° C. or more and 40 ° C. or less for about 60 minutes to 300 minutes after the coating step. When coating is performed while rotating the core body, it is preferable that the core body is continuously rotated from the spin coating process. As a result, the fluorine atom in the multi-branched polymer compound containing a fluorine atom having hydrophobicity moves from the organic polar solvent to the coating film surface layer portion which is a gas boundary surface which is a hydrophobic atmosphere, and the coating film surface layer in contact with the gas The fluorine atom content in the part tends to be high.

  Next, the polyamic acid coating film and the core subjected to the drying step are heated at a temperature of, for example, 250 ° C. or more and 450 ° C. or less for 20 minutes or more and 60 minutes or less, and the polyamic acid coating film which is a polyimide precursor is heated, thereby To form a polyimide layer (heating step). During the thermal imidization treatment, if the solvent remains, the polyimide layer may be swollen. Therefore, it is preferable to remove the residual solvent as much as possible before the thermal imidization treatment. Before the heat treatment, for example, it is preferable to heat and dry at a temperature of 200 ° C. to 250 ° C. for 10 minutes to 30 minutes (preheating step), and then the temperature is increased stepwise or at a predetermined rate. Thus, it is preferable to perform a thermal imidization treatment.

  Thereafter, the core body is cooled by cooling or the like, the polyimide layer is removed from the core body, and an endless belt which is a target tubular member is obtained. By such a method, an endless belt made of polyimide in which a hyperbranched polymer compound containing a releasable fluorine atom is dispersed is produced.

In addition, the endless belt according to the present embodiment improves the surface slipping property on the surface for imparting conductivity for preventing charging, improving durability, improving thermal conductivity, or preventing paper wrinkles. Therefore, the filler may be included. The filler to be blended is preferably at least one selected from the group consisting of metal oxide particles, silicate minerals, carbon black and nitrogen compounds. Among them, particularly from the viewpoint of slipperiness with paper, Ketjen black, graphite, acetylene black, BaSO ₄ , zeolite, silicon oxide, tin oxide, copper oxide, iron oxide, zirconium oxide, ITO (tin-doped oxide) Indium), AZO (aluminum-added zinc oxide), Sb doped SnO ₂ coated TiO ₂ , silicon nitride, boron nitride, titanium nitride, mica, and the like.

  When using a filler, the volume average particle diameter of the filler is in the range of 0.01 μm or more and 20 μm or less from the viewpoints of imparting conductivity and slipperiness to paper, maintaining release properties, and the problem of filler dispersion. Is preferred. The blending ratio of the filler may be set as appropriate, but is preferably set in the range of 0.01 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the polyimide. If the blending ratio of the filler is less than 0.01 parts by mass, the endless belt may have insufficient conductivity, electrostatic offset or charging of the film surface may occur, and the paper slipping property may be insufficient. Yes, paper wrinkles may occur. On the other hand, when the blending ratio of the filler exceeds 30 parts by mass, the releasability is lowered, toner offset is likely to occur, and the surface properties such as the roughness of the surface layer and the gloss are lowered, and the pressure belt or fixing is performed. When used as a belt, there are cases where the glossiness of the image, image blurring, etc. may occur due to surface roughness such as roughness of the surface layer and glossiness.

  As described above, the endless belt has been described as an example of the tubular body according to the present embodiment. However, the tubular body of the present embodiment is not limited to the endless belt, and may be in other forms. As other forms, specifically, for example, a form using the tubular member according to the present embodiment as a roll surface layer such as a roll used for a charging roll, a transfer roll, a pressure roll, a heating roll, etc. .

  Specific examples of the roll include a roll including a core and a roll surface layer formed on the outer peripheral surface of the core, and the roll surface layer is a tubular member according to the present embodiment. . Further, the roll is not limited to this as long as the outermost roll surface layer is a tubular member according to the present embodiment. For example, the roll may include an elastic layer or the like between the core and the roll surface layer.

  The material of the core is not particularly limited, and specific examples include metals such as aluminum, SUS, iron, and copper, alloys, ceramics, FRM (fiber reinforced metal), and the like.

  Examples of the material of the elastic layer include rubbers such as silicone rubber and fluorine rubber. The thickness of the elastic layer is, for example, in the range of 0.1 mm to 3 mm.

  When using the tubular member concerning this embodiment as a roll surface layer of a roll, the thickness of a roll surface layer is the range of 2 micrometers or more and 100 micrometers or less, for example.

<Fixing device>
Next, the configuration of the fixing device according to the present embodiment will be described. The fixing device according to the present embodiment includes a pair of fixing units including a heating member and a pressure member pressed against the heating member, and an unfixed toner image is formed in a nip region formed by the heating member and the pressure member. A fixing device that passes a recording medium to be held and fixes an unfixed toner image by heat and pressure, wherein at least one of a heating member and a pressure member includes a fluorine-containing multibranched polymer compound and polyimide It is an endless belt comprised including the tubular member which has a surface layer containing.

  Hereinafter, the configuration of the fixing device according to the present embodiment will be described with reference to the drawings. However, the present invention is not limited to the following embodiment.

  FIG. 1 is a schematic configuration diagram of a free belt type fixing device. A free belt type fixing device 60 shown in FIG. 1 is a device aiming at further miniaturization, energy saving and high speed in a heating roll / belt type fixing device, and is a support for stretching a belt. There is no roll or pressure roller, it is guided along the belt travel guide 63, and the pressure belt 62 is driven by receiving the driving force from the heating roll 61. Such a belt-type fixing device is In order to distinguish from a type having a support roll and a pressure roll, it is called a free belt type fixing device.

  A free belt type fixing device 60 shown in FIG. 1 is provided with a heating roll 61 and a pressure belt 62 facing each other as a fixing unit, and the pressure belt 62 includes a multi-branch containing fluorine atoms according to the present embodiment. An endless belt comprising a tubular member having a surface layer containing a polymer compound and polyimide is provided. The pressure belt 62 is pressed against the heating roll 61 by a pressure pad (pressure member) 64 disposed inside the circumference, and is guided along the belt running guide 63 as described above while being pressed to form a nip. And driven by receiving a driving force from the heating roll 61.

  The pressure pad 64 has a pre-nip member 64a and a peeling nip member 64b as two pressure portions having different hardness along the traveling direction of the recording medium. The pre-nip member 64a on the recording medium entry side of the pressure pad 64 is composed of a rubber-like elastic member or the like, and the separation nip member 64b on the recording medium discharge side is composed of a hard pressure applying member such as metal, thereby recording the pressure in the nip region. The recording medium discharge side is set higher than the medium entry side. With this configuration, the peelability of the recording medium (particularly a thin recording medium) is improved. The pre-nip member 64a and the peeling nip member 64b are supported by a holder 65, and are connected to the pressure belt 62 via a sliding member 68 having a low friction layer such as a glass fiber sheet or a fluororesin sheet including Teflon (registered trademark). The heating roll 61 is pressed from the inner peripheral surface.

  In the holder 65, a lubricant application member 67 is disposed over the longitudinal direction of the fixing device 60. The lubricant application member 67 is disposed so as to contact the inner peripheral surface of the pressure belt 62 and supplies an appropriate amount of lubricant such as amino-modified silicone oil. Thereby, the lubricant is supplied to the sliding portion between the pressure belt 62 and the sliding member 68, and the sliding resistance between the pressure belt 62 and the pressure pad 64 via the sliding member 68 is reduced.

  The heating roll 61 is configured by sequentially forming an elastic body layer 612 and a release layer 613 on a hollow core metal core 611 made of metal having a heating means such as a heater lamp 66 inside. These metal core 611, elastic body layer 612, and release layer 613 may be made of a conventionally known material.

  Around the heating roll 61, a peeling blade 70 for peeling the recording medium after fixing and a temperature sensor 69 for controlling the temperature of the roll surface are provided. The peeling member 70 includes a peeling baffle 71 that is disposed in a state of being close to the heating roll 61 in a direction facing the rotation direction C of the heating roll 61 (counter direction), and a holder 72 that holds the peeling baffle 71. ing.

  In the fixing device 60 shown in FIG. 1, a recording medium 56 that holds an unfixed toner image P on the surface is conveyed in the direction of an arrow by a conveying means (not shown) and heated with a heating roll 61 that is rotationally driven in the direction of arrow C. The pressure belt 62 is inserted into and passed through a nip region formed by pressure contact. At this time, the recording medium 56 is passed so that the surface of the recording medium 56 on which the unfixed toner image P is formed faces the surface of the heating roll 61. When the recording medium 56 passes through the nip region, heat and pressure are applied to the recording medium 56, whereby the unfixed toner image P is fixed on the recording medium 56. After the fixing, the recording medium 56 passes through the nip region, is peeled off from the heating roll 61 by the peeling member 70, and is discharged from the fixing device 60. In this way, the fixing process is performed.

  In the fixing device 60 according to this embodiment, the time (nip time) that the recording medium holding the unfixed toner image passes through the nip region formed by the heating roll 61 and the pressure belt 62 is 0.030 seconds. The above is preferable. If this nip time is less than 0.030 seconds, it may be difficult to achieve both good fixability and prevention of paper wrinkles and curling, and it is necessary to raise the fixing temperature accordingly, wasting energy. It tends to cause a decrease in durability of parts, a temperature rise of the apparatus, and the like. The upper limit of the nip time is not particularly limited, but is preferably 0.5 seconds or less in view of the balance between the fixing processing capability, the apparatus, and the size of the member.

<Image forming apparatus>
Next, the configuration of the image forming apparatus including the fixing device according to the present embodiment will be described. The image forming apparatus according to the present embodiment includes at least a toner image forming unit that holds an unfixed toner image on a recording medium and the fixing device.

  Hereinafter, the configuration of the image forming apparatus according to the present embodiment will be described with reference to the drawings. However, the present invention is not limited to the following embodiment.

  FIG. 2 is a schematic configuration diagram illustrating an image forming apparatus to which the fixing device according to the present embodiment is applied. An image forming apparatus 3 shown in FIG. 2 is an intermediate transfer type image forming apparatus generally called a tandem type, and includes a plurality of toner image forming units that form toner images of respective color components by electrophotography. Image forming units 1Y, 1M, 1C, and 1K, and a primary transfer unit 10 that sequentially transfers (primary transfer) the color component toner images formed by the image forming units 1Y, 1M, 1C, and 1K to the intermediate transfer belt 15. The secondary transfer unit 20 that collectively transfers (secondary transfer) the superimposed toner image transferred onto the intermediate transfer belt 15 to the recording medium 56 such as recording paper, and the secondary transferred image is fixed onto the recording medium 56. And a fixing device 60 as an example of fixing means to be provided. Further, the image forming apparatus 3 includes a control unit 40 that controls the operation of each device (each unit).

  In the present embodiment, each of the image forming units 1Y, 1M, 1C, and 1K serves as a charging unit that charges the photosensitive drum 11 around the photosensitive drum 11 as an image holding body that rotates in the direction of arrow A. A charging device 12, a laser exposure device 13 as an electrostatic latent image forming unit for forming an electrostatic latent image on the photosensitive drum 11 (exposure beam is indicated by a symbol Bm in FIG. 2), each color component toner is accommodated and photosensitive. A developing device 14 as a developing unit that visualizes the electrostatic latent image on the photoconductive drum 11 with toner, and each color component toner image formed on the photoconductive drum 11 is transferred to the intermediate transfer belt 15 by the primary transfer unit 10. Electrophotographic devices such as a primary transfer roll 16 as a primary transfer means for transferring and a drum cleaner 17 as a cleaning means for removing residual toner on the photosensitive drum 11 are sequentially arranged. It has been. These image forming units 1Y, 1M, 1C, and 1K are arranged substantially linearly in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt 15. Has been.

The intermediate transfer belt 15 as an intermediate transfer member is constituted by a film-like endless belt in which an appropriate amount of an antistatic agent such as carbon black is contained in a resin such as polyimide or polyamide. And the volume resistivity is formed so that it may become the range of 10 < ⁶ > ohm-cm or more and 10 < ¹⁴ > ohm-cm or less, for example, The thickness is comprised about 0.1 mm. The intermediate transfer belt 15 is circulated (rotated) by various rolls at a predetermined speed in the direction B shown in FIG. As these various rolls, a drive roll 31 that is driven by a motor (not shown) having excellent constant speed and circulates and drives the intermediate transfer belt 15, and extends substantially linearly along the arrangement direction of the photosensitive drums 11. A support roll 32 that supports the intermediate transfer belt 15, a tension roll 33 that functions as a correction roll that applies a predetermined tension to the intermediate transfer belt 15 and prevents meandering of the intermediate transfer belt 15, and the secondary transfer unit 20. A backup roll 25 provided, a cleaning backup roll 34 provided in a cleaning unit for scraping off residual toner on the intermediate transfer belt 15 and the like are provided.

The primary transfer unit 10 includes a primary transfer roll 16 that is disposed to face the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. The primary transfer roll 16 is composed of, for example, a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is a columnar rod made of metal such as iron or SUS. The sponge layer is made of, for example, a blend rubber of nitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR) and ethylene-propylene-diene rubber (EPDM) containing a conductive agent such as carbon black, and has a volume resistivity. Is a cylindrical roll such as a sponge having a thickness of 10 ^7.5 Ωcm to 10 ^8.5 Ωcm. The primary transfer roll 16 is disposed in pressure contact with the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. Further, the primary transfer roll 16 has a polarity opposite to the toner charging polarity (negative polarity; the same applies hereinafter). Voltage (primary transfer bias) is applied. As a result, the toner images on the respective photosensitive drums 11 are sequentially electrostatically attracted to the intermediate transfer belt 15 so as to form superimposed toner images on the intermediate transfer belt 15.

The secondary transfer unit 20 includes a secondary transfer roll 22 disposed on the toner image holding surface side of the intermediate transfer belt 15 and a backup roll 25. The backup roll 25 is composed of a tube of EPDM and NBR blend rubber in which, for example, carbon is dispersed, and the inside is made of, for example, EPDM rubber. And it is formed so that the surface resistivity may be in the range of, for example, 10 ⁷ Ω / □ or more and 10 ¹⁰ Ω / □, and the hardness is set to, for example, 70 ° (Asker C: manufactured by Kobunshi Keiki Co., Ltd.). Is done. The backup roll 25 is disposed on the back side of the intermediate transfer belt 15 to constitute a counter electrode of the secondary transfer roll 22 and is disposed in contact with a power supply roll 26 made of metal or the like for applying a secondary transfer bias. .

On the other hand, the secondary transfer roll 22 includes, for example, a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is, for example, a cylindrical rod made of metal such as iron or SUS. The sponge layer is formed of, for example, a blended rubber of NBR, SBR, and EPDM containing a conductive agent such as carbon black, and has a volume resistivity of, for example, 10 ^7.5 Ωcm to 10 ^8.5 Ωcm. A cylindrical roll or the like. The secondary transfer roll 22 is disposed in pressure contact with the backup roll 25 with the intermediate transfer belt 15 interposed therebetween. Further, the secondary transfer roll 22 is grounded and a secondary transfer bias is formed between the secondary transfer roll 22 and the backup roll 25. Then, the toner image is secondarily transferred onto the recording medium 56 conveyed to the secondary transfer unit 20.

  Further, on the downstream side of the secondary transfer portion 20 of the intermediate transfer belt 15, intermediate transfer that removes residual toner, paper dust, and the like on the intermediate transfer belt 15 after the secondary transfer and cleans the surface of the intermediate transfer belt 15. A belt cleaner 35 is provided so as to be able to contact and separate. On the other hand, on the upstream side of the yellow image forming unit 1Y, a reference sensor (home position sensor) 42 that generates a reference signal serving as a reference for taking image forming timings in the image forming units 1Y, 1M, 1C, and 1K. It is arranged. Further, an image density sensor 43 for adjusting image quality is disposed on the downstream side of the black image forming unit 1K. The reference sensor 42 recognizes a predetermined mark or the like provided on the back side of the intermediate transfer belt 15 and generates a reference signal. Each image is received by an instruction from the control unit 40 based on the recognition of the reference signal. The forming units 1Y, 1M, 1C, and 1K are configured to start image formation.

  Furthermore, in the image forming apparatus 3 of the present embodiment, as a paper transport system, for example, a paper tray 50 that accommodates the recording medium 56, and a pickup that picks up and transports the recording medium 56 accumulated in the paper tray 50 at a predetermined timing. A roll 51, a transport roll 52 that transports the recording medium 56 fed out by the pickup roll 51, a transport chute 53 that feeds the recording medium 56 transported by the transport roll 52 to the secondary transfer unit 20, and the secondary transfer roll 22. A conveyance belt 55 that conveys the recording medium 56 conveyed after the secondary transfer to the fixing device 60, a fixing inlet guide 57 that guides the recording medium 56 to the fixing device 60, and the like are provided.

  Next, an example of a basic image forming process of the image forming apparatus according to the present embodiment will be described. In the image forming apparatus as shown in FIG. 2, image data output from an image reading device (IIT) not shown or a personal computer (PC) not shown is subjected to predetermined image processing by an image processing device (IPS) not shown. Is applied, the image forming operation is executed by the image forming units 1Y, 1M, 1C, and 1K. In IPS, the input reflectance data is subjected to predetermined image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, moving editing, and other various image editing. Is done. The image data that has been subjected to image processing is converted into color material gradation data of four colors Y, M, C, and K, and is output to the laser exposure unit 13.

  The laser exposure unit 13 irradiates, for example, an exposure beam Bm emitted from a semiconductor laser to the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K according to the input color material gradation data. In each of the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K, the surface is charged by the charger 12, and then the surface is scanned and exposed by the laser exposure unit 13 to form an electrostatic latent image. The formed electrostatic latent image is developed as a toner image of each color of Y, M, C, and K in each of the image forming units 1Y, 1M, 1C, and 1K.

  The toner images formed on the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K are transferred onto the intermediate transfer belt 15 at the primary transfer unit 10 where the photosensitive drums 11 and the intermediate transfer belt 15 are in contact with each other. Is transcribed. More specifically, in the primary transfer unit 10, a voltage (primary transfer bias) having a polarity opposite to the charging polarity (minus polarity) of the toner is applied to the base material of the intermediate transfer belt 15 by the primary transfer roll 16. Primary transfer is performed by sequentially superimposing images on the surface of the intermediate transfer belt 15.

  After the toner images are sequentially primary transferred onto the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves and the toner image is conveyed to the secondary transfer unit 20. When the toner image is transported to the secondary transfer unit 20, in the paper transport system, the pick-up roll 51 rotates in accordance with the timing at which the toner image is transported to the secondary transfer unit 20, and the predetermined size from the paper tray 50 is reached. A recording medium 56 is supplied. The recording medium 56 supplied by the pickup roll 51 is conveyed by the conveyance roll 52 and reaches the secondary transfer unit 20 via the conveyance chute 53. Before reaching the secondary transfer unit 20, the recording medium 56 is temporarily stopped, and a registration roll (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 15 on which the toner image is held. The position of the medium 56 and the position of the toner image are aligned.

  In the secondary transfer unit 20, the secondary transfer roll 22 is pressed against the backup roll 25 via the intermediate transfer belt 15. At this time, the recording medium 56 conveyed at the same timing is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. At this time, when a voltage (secondary transfer bias) having the same polarity as the toner charging polarity (negative polarity) is applied from the power supply roll 26, a transfer electric field is formed between the secondary transfer roll 22 and the backup roll 25. Is done. The unfixed toner image held on the intermediate transfer belt 15 is collectively electrostatically transferred onto the recording medium 56 by the secondary transfer unit 20 pressed by the secondary transfer roll 22 and the backup roll 25. Is done.

  Thereafter, the recording medium 56 on which the toner image is electrostatically transferred is conveyed as it is while being peeled off from the intermediate transfer belt 15 by the secondary transfer roll 22, and is provided downstream of the secondary transfer roll 22 in the sheet conveying direction. It is conveyed to the conveyor belt 55. The conveying belt 55 conveys the recording medium 56 to the fixing device 60 in accordance with the optimum conveying speed in the fixing device 60. The unfixed toner image on the recording medium 56 conveyed to the fixing device 60 is fixed on the recording medium 56 by being subjected to a fixing process by heat and pressure by the fixing device 60. Then, the recording medium 56 on which the fixed image is formed is conveyed to a paper discharge mounting portion provided in a discharge portion of the image forming apparatus.

  On the other hand, after the transfer to the recording medium 56 is completed, the residual toner or the like remaining on the intermediate transfer belt 15 is conveyed to the cleaning unit as the intermediate transfer belt 15 is driven to rotate, and the cleaning backup roll 34 and the intermediate transfer belt. It is removed from the intermediate transfer belt 15 by the cleaner 35.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

  The measuring method of the physical property values used in this example is as follows.

<Fluorine atom content>
As described above, “VG ESCALAB-220i” is used as an XPS measurement device, and measurement is performed using a monochromatic AlKα ray as an X-ray source, setting an acceleration voltage to 10 kV, and an emission current to 20 mV. Measured for fluorine atoms. The analysis region was about 1 mmφ, and the detection depth was 3 nm. And C1s spectrum was measured about the fluorine atom, the number of elements was calculated | required based on the spectrum of the said fluorine atom, and the fluorine atom content rate with respect to the total atomic weight of a surface layer was computed.

<Contact angle with pure water>
To measure the contact angle with pure water, which is an evaluation standard for the functional surface of an endless belt, a surface contact angle measuring device (DM-301 type) manufactured by Kyowa Interface Science Co., Ltd. is used, and ion-exchanged water is applied to the sample surface. A water droplet was dropped, and the contact angle between the water droplet and the sample surface was measured from the side surface.

  Further, the evaluation of the wear resistance of the endless belt against paper rubbing and the releasability from the toner was performed by the following method.

[Evaluation]
The obtained endless belt is mounted as a pressure belt on the image forming apparatus DCC400 manufactured by Fuji Xerox Co., which is equipped with a free belt type heating roll / pressure belt type fixing device (see FIG. 1). Went. The results are shown in Table 1.

<Abrasion resistance of pressure belt>
The wear resistance of the pressure belt was evaluated as follows. The image forming apparatus was set so that an 800 W halogen lamp heater was installed inside the heating roll and had a set temperature of 150 ° C., a speed of 150 mm / sec, and a nip width of 8 mm. As the toner, color toner (cyan) for DocuCenterColor400 manufactured by Fuji Xerox Co., Ltd. was used and fixed on “J paper” manufactured by Fuji Xerox Co., Ltd. Under the above conditions, 100,000 sheets (100 kpv) were tested, and the abrasion resistance was evaluated by measuring the thickness of the pressure belt after the test and determining the amount of decrease per 1 kpv as the amount of wear. It was.

<Releasability of pressure belt>
Evaluation of releasability of the pressure belt was performed as follows. The conditions of the image forming apparatus are the same as in the abrasion resistance evaluation described above, and 100 samples are printed with double-sided output. The number of jams was evaluated.

Example 1
First, as a polyamic acid composition, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine are synthesized in N-methyl-2-pyrrolidone (NMP). A solution containing the obtained polyamic acid and having a solid content concentration of 18% by mass and a viscosity of 20 Pa · s was prepared. Specifically, 334.4 g of NMP was placed in a 2000 ml flask equipped with a stirring blade and heated to 60 ° C. 0.1 mol of p-phenylenediamine was added and stirred until completely dissolved. While continuing heating and stirring, 0.1 mol of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was gradually added and dissolved. After dissolving 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, the polyamic acid polymerization reaction proceeds, and after the viscosity of the solution has increased, 200 g of NMP was added and diluted to 20% by mass. The solution was cooled to room temperature (25 ° C.) to obtain a polyamic acid solution.

Next, as a multi-branched polymer compound containing fluorine atoms in this polyamic acid composition, a fluorine atom-containing hyperbranched polymer (FA-200; manufactured by Nissan Chemical Industries, Ltd., structure: represented by the above structural formula (1) A compound (R ₁ = methyl group, R ₂ = fluorine atom, Y =-(CF ₂ ) _n- , n = 10) and a copolymer of ethylene glycol dimethacrylate, number average molecular weight 50,000) is converted to polyamic acid. It added and stirred so that it might become a density | concentration of 10 mass% with respect to solid content of a composition.

  The polybranched polymer-containing polyamic acid composition obtained in this manner was applied to the surface of a cylindrical aluminum mold (cylindrical core) having an inner diameter of 30 mm and a length of 450 mm by a rotational spiral coating method. Formed. The cylindrical core was preliminarily coated with a silicone release agent as a release agent on the surface, thereby improving the peelability after belt formation.

  Next, the core was dried at 100 ° C. for 60 minutes under a nitrogen gas atmosphere in a state where the core was rotated in the cylinder circumferential direction at 20 rpm. After the drying step, the core was put in an oven and gradually heated to 350 ° C. in a nitrogen gas atmosphere to be imidized. Stepwise heating was performed at 160 ° C. for 1 hour, 250 ° C. for 30 minutes, and 350 ° C. for 1 hour. Thereafter, the core was allowed to cool at room temperature (25 ° C.), the resin was removed from the core, and the intended endless belt was obtained. The fluorine atom content on the endless belt surface measured by X-ray photoelectron spectroscopy (XPS) was 8%.

  As a result of measuring the contact angle of the outer peripheral surface of the obtained endless belt with pure water, it was 110 degrees. As shown in Table 1, sufficient wear resistance and releasability were obtained for the wear resistance and releasability.

(Example 2)
A polyamic acid composition was prepared in the same manner as in Example 1. A fluorine atom-containing hyperbranched polymer was added to this polyamic acid composition in the same manner as in Example 1 to 2% by mass with respect to the solid content of the polyamic acid composition. Added to a concentration and stirred. An endless belt was produced in the same manner as in Example 1, and the contact angle with pure water on the outer peripheral surface was measured. As a result, it was 85 degrees. As shown in Table 1, the wear resistance and releasability were sufficient, but the releasability was slightly insufficient. The fluorine atom content on the surface of the endless belt measured by X-ray photoelectron spectroscopy (XPS) was 1.5%.

(Example 3)
A polyamic acid composition was prepared in the same manner as in Example 1, and a fluorine atom-containing hyperbranched polymer was added to the polyamic acid composition in the same manner as in Example 1 in an amount of 78% by mass based on the solid content of the polyamic acid composition. Added to a concentration and stirred. As a result of producing an endless belt in the same manner as in Example 1 and measuring the contact angle with pure water on the outer peripheral surface, it was 115 degrees. As shown in Table 1, sufficient wear resistance and releasability were obtained for the wear resistance and releasability. The fluorine atom content on the endless belt surface measured by X-ray photoelectron spectroscopy (XPS) was 55%.

Example 4
A polyamic acid composition was prepared in the same manner as in Example 1, and a fluorine atom-containing hyperbranched polymer was added to the polyamic acid composition in the same manner as in Example 1 to 95% by mass with respect to the solid content of the polyamic acid composition. Added to a concentration and stirred. As a result of producing an endless belt in the same manner as in Example 1 and measuring the contact angle of the outer peripheral surface with pure water, it was 125 degrees. As shown in Table 1, the wear resistance and releasability were sufficient, but the wear resistance was slightly lowered. The fluorine atom content on the surface of the endless belt measured by X-ray photoelectron spectroscopy (XPS) was 75%.

(Example 5)
A polyamic acid composition was prepared in the same manner as in Example 1, and a fluorine atom-containing hyperbranched polymer was added to this polyamic acid composition in an amount of 90% by mass based on the solid content of the polyamic acid composition in the same manner as in Example 1. Added to a concentration and stirred. As a result of producing an endless belt in the same manner as in Example 1 and measuring the contact angle of the outer peripheral surface with pure water, it was 120 degrees. As shown in Table 1, sufficient wear resistance and releasability were obtained for the wear resistance and releasability. The fluorine atom content on the surface of the endless belt measured by X-ray photoelectron spectroscopy (XPS) was 70%.

(Example 6)
A polyamic acid composition was prepared in the same manner as in Example 1. A fluorine atom-containing hyperbranched polymer was added to this polyamic acid composition in the same manner as in Example 1 in an amount of 1% by mass based on the solid content of the polyamic acid composition. Added to a concentration and stirred. An endless belt was produced in the same manner as in Example 1, and the contact angle with pure water on the outer peripheral surface was measured and found to be 83 degrees. As shown in Table 1, the wear resistance and releasability were sufficient, but the releasability was slightly insufficient. The fluorine atom content of the endless belt surface measured by X-ray photoelectron spectroscopy (XPS) was 1%.

(Example 7)
A polyamic acid composition was prepared in the same manner as in Example 1, and a fluorine atom-containing hyperbranched polymer was added to this polyamic acid composition in the same manner as in Example 1 with respect to the solid content of the polyamic acid composition by 0.5 mass. % Concentration was added and stirred. An endless belt was produced in the same manner as in Example 1, and the contact angle with pure water on the outer peripheral surface was measured. As a result, it was 77 degrees. As shown in Table 1, the wear resistance and releasability were sufficient, but the releasability was insufficient. The fluorine atom content on the surface of the endless belt measured by X-ray photoelectron spectroscopy (XPS) was 0.5%.

(Example 8)
A polyamic acid composition was prepared in the same manner as in Example 1, and a fluorine atom-containing hyperbranched polymer was added to the polyamic acid composition in the same manner as in Example 1 to 85% by mass with respect to the solid content of the polyamic acid composition. Added to a concentration and stirred. An endless belt was produced in the same manner as in Example 1, and the contact angle with pure water on the outer peripheral surface was measured. As a result, it was 118 degrees. As shown in Table 1, sufficient wear resistance and releasability were obtained for the wear resistance and releasability. The fluorine atom content on the surface of the endless belt measured by X-ray photoelectron spectroscopy (XPS) was 64%.

Example 9
A polyamic acid composition was prepared in the same manner as in Example 1. A fluorine atom-containing hyperbranched polymer was added to this polyamic acid composition in the same manner as in Example 1 in an amount of 5% by mass based on the solid content of the polyamic acid composition. Added to a concentration and stirred. As a result of producing an endless belt in the same manner as in Example 1 and measuring the contact angle of the outer peripheral surface with pure water, it was 100 degrees. As shown in Table 1, sufficient wear resistance and releasability were obtained for the wear resistance and releasability. The fluorine atom content on the surface of the endless belt measured by X-ray photoelectron spectroscopy (XPS) was 4%.

(Comparative Example 1)
A polyamic acid composition was prepared in the same manner as in Example 1 and applied to the surface of the cylindrical core in the same manner as in Example 1 without adding the fluorine atom-containing hyperbranched polymer to form a coating film. Next, the core was dried at 100 ° C. for 60 minutes under a nitrogen gas atmosphere in a state where the core was rotated in the cylinder circumferential direction at 20 rpm.

  After the drying step, an aqueous paint (fluorine resin dispersion, solid content concentration 60 mass%, viscosity 200 mPa · s) containing polytetrafluoroethylene (PTFE, weight average molecular weight 500,000) containing water as a solvent was prepared. This paint was applied on the dried polyamic acid coating film by a spiral coating method, and after coating, it was dried in an airless drying oven at 80 ° C. for 10 minutes. After drying, it was imidized in an oven in the same manner as in Example 1. Thereafter, the mold was removed from the core to obtain a polyimide endless belt. The fluorine atom content on the surface of the endless belt measured by X-ray photoelectron spectroscopy (XPS) was 67%. As a result of measuring the contact angle of the endless belt surface with pure water, it was 135 degrees. As a result of the evaluation of the wear resistance and the release property, as shown in Table 1, the wear resistance was greatly reduced as compared with the Examples.

(Comparative Example 2)
A polyamic acid composition was prepared in the same manner as in Example 1, and a fluorine atom-containing hyperbranched polymer was not added, and the same was applied to the surface of the cylindrical core as in Example 1, imidized, and endless as in Example 1. A belt was produced. As a result of measuring the contact angle of the outer peripheral surface with pure water, it was 70 degrees. As a result of the evaluation of wear resistance and releasability, as shown in Table 1, 100 sheets of jams were generated by double-sided output paper passing.

(Comparative Example 3)
A polyamic acid composition was prepared in the same manner as in Example 1, and polytetrafluoroethylene particles (weight average molecular weight 20,000, volume average particle size 2 μm) were added to the polyamic acid composition based on the solid content of the polyamic acid composition. And added to a concentration of 30% by mass and stirred. An endless belt was produced in the same manner as in Example 1, and the contact angle with pure water on the outer peripheral surface was measured. As a result, it was 90 degrees. As shown in Table 1, the wear resistance and releasability were insufficient, and the wear resistance was insufficient. The fluorine atom content on the surface of the endless belt measured by X-ray photoelectron spectroscopy (XPS) was 12%.

  Thus, the endless belt of the example configured to include the tubular member having the surface layer including the multi-branched polymer compound containing fluorine atoms and the polyimide is more resistant to abrasion than the endless belt of the comparative example. And it was excellent in releasability.

  1Y, 1M, 1C, 1K Image forming unit, 3 image forming apparatus, 10 primary transfer unit, 11 photosensitive drum, 12 charger, 13 laser exposure unit, 14 developing unit, 15 intermediate transfer belt, 16 primary transfer roll, 17 Drum cleaner, 20 Secondary transfer section, 22 Secondary transfer roll, 25 Backup roll, 26 Feed roll, 31 Drive roll, 32 Support roll, 33 Tension roll, 34 Cleaning backup roll, 35 Intermediate transfer belt cleaner, 40 Control section, 42 reference sensor, 43 image density sensor, 50 paper tray, 51 pick-up roll, 52 transport roll, 53 transport chute, 55 transport belt, 56 recording medium, 57 fixing inlet guide, 60 fixing device, 61 heating roll, 62 pressure belt , 63 Belt running guy , 64 Pressure pad, 64a Pre-nip member, 64b Peel nip member, 65 holder, 66 Heater lamp, 67 Lubricant application member, 68 Sliding member, 69 Temperature sensor, 70 Peel member, 71 Peel baffle, 72 Holder, 611 Hollow Core metal core, 612 elastic layer, 613 release layer, P unfixed toner image, Bm exposure beam.

Claims (5)

  A tubular member comprising a surface layer containing a multi-branched polymer compound containing fluorine atoms and polyimide.   2. The tubular member according to claim 1, wherein a fluorine atom content of the surface layer measured by X-ray photoelectron spectroscopy (XPS) is in a range of 1% to 90%.   An endless belt comprising the tubular member according to claim 1 or 2. A pair of fixing units including a heating member and a pressure member pressed against the heating member, and passing a recording medium holding an unfixed toner image in a nip region formed by the heating member and the pressure member Fixing the unfixed toner image by heat and pressure,
The fixing device according to claim 3, wherein at least one of the heating member and the pressure member is the endless belt according to claim 3.   An image forming apparatus comprising: at least a toner image forming unit that holds an unfixed toner image on a recording medium; and the fixing device according to claim 4.

Images