JP2007293028A - Seamless belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the wear resistance of a belt and to provide a seamless belt which suppresses occurrence of abrasion powder. <P>SOLUTION: The seamless belt is made of a polyimide resin containing fluorocarbon resin powder and an inorganic filler. The fluorocarbon resin powder is contained in a polyimide resin-based composition in an amount of 0.5-20 wt.% and the spherical inorganic filler having an average particle diameter of 1-15 μm is contained in the polyimide resin-based composition in an amount of 0.1-10 wt.%. The inner circumferential surface of the seamless belt has a surface roughness Ra of 0.06-0.6 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a seamless belt or a composite seamless belt (or sometimes referred to as a multi-layer seamless belt) that can be used as a transfer fixing belt, a fixing belt, or the like in an electrophotographic image forming apparatus such as a copying machine, a laser beam printer, or a facsimile machine. About.

  As an electrophotographic recording apparatus for forming and recording an image by a conventional electrophotographic system, a copying machine, a laser beam printer, a facsimile, and a complex machine of these are known. In this type of apparatus, a fixing method using a seamless belt is employed for the purpose of speeding up image formation and saving energy.

  As an example of the fixing method using the seamless belt, there is exemplified a system in which a film-like belt is placed along a heat roller to widen the nip width and the toner on the recording material is heated. In this fixing method, since the film-like belt is in contact with the heat roller, the nip width can be widened, and the fixing time is shortened (the number of printed sheets is substantially increased by shortening the fixing time), There is a merit of reducing power consumption by lowering the fixing temperature.

  As a seamless belt used in the fixing method as described above, a composite seamless belt (see Patent Document 1) composed of a polyimide resin inner layer and a fluororesin outer layer excellent in heat resistance and mechanical strength is known. Moreover, the method of using the belt containing an inorganic filler is devised for the purpose of improving thermal conductivity (refer patent document 2).

Japanese Patent Laid-Open No. 3-130145 JP-A-7-110632

  In recent years, copying machines, printers, and the like have been remarkably increased in color, increased in size, and increased in speed as the user's usage environment changes. Therefore, the nip surface where the belt and the roller come in contact with each other is widened, and the surface pressure of the nip surface is increased to ensure the finished quality. Therefore, the inner surface of the belt continues to slide at high pressure and high speed.

  For this reason, in the case of a belt composed of only a normal polyimide resin, the belt surface is worn in proportion to the number of times of use, and wear resistance has been a problem. Further, in the case of a belt made of a polyimide resin dispersed with a fluororesin in order to impart slidability, the problem of wear resistance cannot be completely solved, and an improvement has been demanded.

  In addition, if the belt wears further, the belt itself may be deformed and broken. However, the problem here is the wear powder generated by the wear. This wear powder impairs the good rotation of the belt. As a specific problem, there is a problem that wrinkles occur on the image-formed paper and the quality is deteriorated.

  Accordingly, an object of the present invention is to provide a seamless belt that improves the wear resistance of the belt and suppresses the generation of wear powder.

  The inventors of the present invention have intensively studied to achieve the above object, and have added fluororesin powder for the purpose of reducing slidability and further adding inorganic fillers to suppress the generation of wear powder. The headline and the present invention were completed.

That is, the seamless belt of the present invention is a seamless belt made of polyimide resin containing a fluororesin powder and an inorganic filler,
The fluororesin powder contains 0.5 to 20% by weight in the polyimide resin composition,
The spherical inorganic filler having an average particle diameter of 1 to 15 μm is contained in the polyimide resin composition in an amount of 0.1 to 10% by weight,
The surface roughness Ra of the inner peripheral surface of the seamless belt is 0.06 to 0.6 μm.

  According to this configuration, the surface roughness (Ra) of the inner circumferential surface of the belt is increased, and wear can be reduced. (It is considered that the contact area is reduced.) As a result, it is possible to provide a seamless belt that improves the wear resistance of the belt and suppresses the generation of wear powder.

  In the present invention, the spherical inorganic filler is preferably one or a mixture of two or more selected from the group of silica, alumina, quartz and aluminum nitride.

  Moreover, in this invention, it is preferable to have a release layer made of a fluororesin on the belt outer periphery of the seamless belt.

  The seamless belt of the present invention is a polyimide resin seamless belt containing a fluororesin powder and an inorganic filler (hereinafter sometimes referred to as an inorganic filler), and the fluororesin powder is contained in the polyimide resin composition. The spherical inorganic filler containing 0.5 to 20% by weight and having an average particle diameter of 1 to 15 μm is contained in the polyimide resin composition in an amount of 0.1 to 10% by weight. And the surface roughness Ra of the inner peripheral surface of the said seamless belt is 0.06-0.6 micrometer. Below, the structure of the seamless belt of this invention is demonstrated.

(Inorganic filler)
The inorganic filler is not particularly limited as long as it has irregularities on the surface and has a hardness that can withstand abrasion, and examples thereof include alumina, silica, quartz, and aluminum nitride. These can be used alone or in combination. In addition, it is preferable that the inorganic filler has a spherical surface shape because it does not attack the counterpart material (for example, a roller of a belt rotation spindle, a transfer object, etc.).

  The content of the inorganic filler needs to be set in the range of 0.1 to 10% by weight in the polyimide resin composition. Especially preferably, it is the range of 0.5 to 5 weight%. Within such a range, the unevenness on the inner peripheral surface can be sufficiently expressed, which is preferable. In addition, since the surface roughness (Ra) of an internal peripheral surface does not become coarse when content of the said inorganic filler is less than 0.1 weight%, it is unpreferable. On the other hand, if the content exceeds 10% by weight, the seamless belt obtained by this is not preferable because the mechanical strength is low and cracks and cracks are likely to occur.

  Furthermore, the average particle size of the primary particles of the inorganic filler is preferably set in the range of 0.1 to 15 μm. More preferably, it is the range of 0.5-2.0 micrometers. Within such a range, there is little agglomeration of particles and the particles are uniformly dispersed, so that there is no variation in thermal conductivity and strength, and for example, the strength as a fixing belt can be maintained, which is preferable. . Here, the primary particle refers to the smallest particle constituting the powder. As the particle size distribution, a substantially normal distribution is taken, and a normal curve extending from a range of 1.0 to 1.5 μm as a small particle size to a range of 7 to 13 μm as a large particle size is taken.

  If the average particle size is less than 0.01 μm, it is not preferable because irregularities are likely to occur on the inner peripheral surface and the outer peripheral surface of the obtained seamless belt due to aggregation of the particles. On the other hand, if the thickness exceeds 15 μm, the particles become large, and therefore unevenness due to the particles tends to occur on the inner and outer peripheral surfaces of the obtained seamless belt, which is not preferable. The average particle size of the primary particles of the inorganic filler can be measured by a particle size distribution measuring instrument using a light transmission centrifugal sedimentation method using, for example, a liquid ultrasonically dispersed in an organic solvent such as ethanol. The measurement method is measured based on JIS Z8823-2.

(Fluorine resin powder)
Examples of the fluororesin powder include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and ethylene-tetrafluoro. An ethylene copolymer (ETFE) etc. are illustrated. In particular, polytetrafluoroethylene (PTFE) is preferable because it has high heat resistance and a small coefficient of dynamic friction.

  The content of the fluororesin powder needs to be set in the range of 0.1 to 20% by weight in the polyimide resin composition. Especially preferably, it is the range of 0.5 to 10 weight%. If the content of the fluororesin powder is less than 0.1% by weight, the effect of reducing the friction coefficient cannot be obtained, which is not preferable. On the other hand, if it exceeds 20% by weight, the seamless belt obtained thereby is not preferable because it has a low elastic modulus and lacks abrasion resistance.

  Furthermore, it is preferable that the average particle diameter of the said fluororesin powder is set to the range of 0.01-5.0 micrometers. More preferably, it is the range of 0.5-5.0 micrometers. Within such a range, there is little agglomeration of particles and the particles are uniformly dispersed, so that there is no variation in thermal conductivity and strength, and for example, the strength as a fixing belt can be maintained, which is preferable. Here, the primary particle refers to the smallest particle constituting the powder. As the particle size distribution, a substantially normal distribution is taken, and a normal curve extending from a range of 1.0 to 1.5 μm as a small particle size to a range of 7 to 13 μm as a large particle size is taken.

  If the average particle size is less than 0.01 μm, it is not preferable because irregularities are likely to occur on the inner peripheral surface and the outer peripheral surface of the obtained seamless belt due to aggregation of the particles. On the other hand, if the thickness exceeds 5.0 μm, the particles become large, and therefore unevenness due to the particles tends to occur on the inner peripheral surface and the outer peripheral surface of the obtained seamless belt, which is not preferable. In addition, the measuring method of the average particle diameter of the said fluororesin powder is based on the measuring method of the primary particle average particle diameter of the said inorganic filler.

(Polyimide resin composition)
The seamless belt of the present invention is a seamless belt made of a polyimide resin-based composition containing a polyimide resin as a main component. Here, the “main component” is a main component constituting the polyimide resin-based composition, and means that it greatly affects the properties of the composition.

  The polyimide resin is a polyamic acid obtained by imide conversion. The polyamic acid, which is a polyimide resin precursor, can be obtained by reacting approximately equimolar amounts of tetracarboxylic dianhydride or its derivative and diamine in an organic solvent (this is a conventionally known method). ).

  As said tetracarboxylic dianhydride, what is represented by following General formula (1) is mention | raise | lifted.

［式（Ｉ）中、Ｒは４価の有機基であり、芳香族、脂肪族、環状脂肪族、芳香族と脂肪族とを組み合わせたもの、またはそれらの置換された基である。］

[In Formula (I), R is a tetravalent organic group, and is an aromatic, aliphatic, cycloaliphatic, a combination of aromatic and aliphatic, or a substituted group thereof. ]

  Specific examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′- Biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalene Tetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-di Carboxyphenyl) sulfonic acid dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylenetetracarboxylic dianhydride, etc. And the like.

Specific examples of diamines to be reacted with such tetracarboxylic dianhydrides include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, and 3,3′-. Dichlorobenzidine, 4,4′-diaminodiphenyl sulfide-3,3′-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl-4,4′- Biphenyldiamine, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 4,4′-diaminophenylsulfone, 4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenylpropane, 2, 4-Bis (β-amino-tert-butyl) toluene, bis (p-β-amino-tertiary Tilphenyl) ether, bis (p-β-methyl-δ-aminophenyl) benzene, bis-p- (1,1-dimethyl-5-amino-pentyl) benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylhepta Methylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5- Dimethylhexamethyle Diamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methylnonamethylenediamine, 2,11-diaminododecane, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1, 10-diamino-1,10-dimethyldecane, 1,12-diaminooctadecane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, piperazine, H ₂ N (CH ₂ ) ₃ O (CH ₂ ) ₂ OCH ₂ NH ₂ , H ₂ N (CH ₂ ) ₃ S (CH ₂ ) ₃ NH ₂ , H ₂ N (CH ₂ ) ₃ N (CH ₃ ) (CH ₂ ) ₃ NH _{2 and the} like.

  One or more of these tetracarboxylic dianhydrides or their derivatives and diamines can be appropriately selected and reacted.

  The organic polar solvent used when the tetracarboxylic dianhydride and diamine are reacted has a dipole whose functional group does not react with the tetracarboxylic dianhydride or diamine. It must be inert to the system and act as a solvent for the product polyamic acid. Moreover, it must act as a solvent for at least one of the reaction components, preferably both.

  As the organic polar solvent, N, N-dialkylamides are particularly useful, and examples thereof include N, N-dimethylformamide and N, N-dimethylacetamide, which have low molecular weight. These can be easily removed from the polyamic acid and the polyamic acid molded article by evaporation, displacement or diffusion.

  Other organic polar solvents include N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine , Tetramethylene sulfone, dimethyltetramethylene sulfone and the like. These may be used alone or in combination.

  Furthermore, phenols such as cresol, phenol and xylenol, benzonitrile, dioxane, butyrolactone, xylene, cyclohexane, hexane, benzene, toluene and the like can be mixed alone or in combination with the organic polar solvent. However, it is preferable to avoid the use of water in order to prevent lowering the molecular weight due to hydrolysis of the produced polyamic acid.

The seamless belt of the present invention is prepared by adding and mixing a predetermined amount of inorganic filler, fluororesin powder, and catalyst to the above polyamic acid solution, and developing it by an appropriate method (coating and developing on the inner surface or outer surface of a cylindrical mold). ), A method of removing the solvent of the spreading layer by heating and drying (a method having an imidization step).

  Examples of the catalyst include trimethylamine, triethylamine, triethylenediamine, tributylamine, dimethylaniline, pyridine, α-picoline, β-picoline, γ-picoline, isoquinoline, lutidine and other tertiary amines, 1,5-diazabicyclo [4. Examples include organic bases such as 3.0] nonene-5,1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo [5.4.0] undecene-7. Isoquinoline is particularly preferred from the viewpoints of releasability from the mold and flexibility and rigidity of the belt. These catalysts provide the function of an imidizing agent and can be used alone or in combination with a dehydrating agent. In addition, there is a known method of heating at a high temperature as a method not using these catalysts during imide conversion.

(Preparation method of polyamic acid solution)
The polyamic acid solution is preferably obtained by reacting the tetracarboxylic dianhydride (x) and the diamine (y) in an organic polar solvent for about 0.5 to 10 hours. That is, if it is less than 0.5 hours, the reaction becomes insufficient, and even if it exceeds 10 hours, no further effect can be obtained. The monomer concentration during the reaction [concentration of (x) + (y) in the solvent] can be set according to various factors, but is usually 5 to 30% by weight. The reaction temperature is preferably set to 80 ° C. or lower.

  In addition, when tetracarboxylic dianhydride and diamine are reacted in an organic polar solvent in this way, the viscosity of the solution increases with the progress of the reaction. In the present invention, the logarithmic viscosity (η) is 0. It is preferable to use a polyamic acid solution having a viscosity of 5 or more. That is, when formed using a polyamic acid solution having a logarithmic viscosity (η) of 0.5 or more, the reliability against heat degradation (heat resistance) is particularly excellent compared to that having a logarithmic viscosity of less than 0.5. There are advantages. The logarithmic viscosity (η) is a value calculated by the following mathematical formula (1) by measuring the dropping time of the polyamic acid solution and the solvent using a capillary viscometer.

このようなポリアミド酸溶液は、使用する際に、粘度が高い場合には適当な溶媒で希釈して粘度を低くして用いる。例えば、ポリアミド酸溶液の粘度は、塗布厚み、シリンダーの内径、溶液温度、走行体の形状等に応じて設定されるが、通常、１０〜１００００ポイズ（塗布作業時の温度（約２５℃）でＢ型粘度計にて測定）に設定される。

When such a polyamic acid solution has a high viscosity, it is diluted with an appropriate solvent to lower the viscosity. For example, the viscosity of the polyamic acid solution is set according to the coating thickness, the cylinder inner diameter, the solution temperature, the shape of the traveling body, etc., but is usually 10 to 10000 poise (at the temperature during coating operation (about 25 ° C.)). Measured with a B-type viscometer).

For example, when preparing the above-mentioned polyamic acid, the polyamic acid solution is charged into an appropriate disperser such as a planetary mixer, a bead mill, or a three-roll roll. The PTFE powder is added while mixing, and the PTFE powder is mixed and dispersed in the polyamic acid solution. Next, the polyamic acid solution in which the PTFE powder is mixed and dispersed can be performed by an appropriate method such as a method for subjecting it to film forming. Of course, after completion of the reaction between the tetracarboxylic dianhydride and the diamine in the organic polar solvent, each may be added to the polyamic acid solution and mixed uniformly.

(Release layer made of fluororesin)
It is preferable to provide a release layer made of a fluororesin on the outer peripheral surface of the seamless belt of the present invention. When a seamless belt is used for fixing, it is preferable to provide this release layer since the toner releasability is improved.

  The material constituting the release layer is preferably a fluororesin, specifically, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer. A polymer (ETFE) etc. can be mentioned. Among these, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) is particularly preferable from the viewpoint of preventing toner contamination.

  The release layer may contain a conductive material in order to impart conductivity. Specific conductive materials include carbon blacks such as ketjen black and acetylene black, inorganic compounds such as aluminum, nickel, tin oxide, and potassium titanate, and conductive polymers typified by polyaniline and polypyrrole. it can.

  The thickness of the release layer is appropriately selected depending on the application or the design of the apparatus, but the release layer is usually 5 to 50 μm.

(Seamless belt manufacturing method)
As described above, the seamless belt (film-shaped polyimide resin belt) of the present invention is obtained by adding a predetermined amount of inorganic filler and fluororesin powder to the polyamic acid solution (and further adding a catalyst as the imidizing agent). In some cases, the mixture is mixed and spread by an appropriate method (applied and spread on the inner surface or outer surface of the cylindrical mold), and the solvent in the spread layer is removed by heating (a method having an imidization step). Can be obtained by forming into a film. This film thickness can be appropriately determined according to the purpose of use of the polyimide resin belt. In general, the film thickness is preferably 5 to 500 μm, more preferably 10 to 300 μm, and particularly preferably 15 to 125 μm, in view of mechanical properties such as strength and flexibility.

The composite seamless belt of the present invention can be produced, for example, by the following steps.
(1) First, a cylindrical mold is prepared as a molding mold, and a polyamic acid solution containing an inorganic filler and a fluororesin powder is applied to the inner peripheral surface of the cylindrical mold.
(2) After coating, the coated film is dried and cured until it can support at least itself, or heated until imide conversion is completed, thereby forming a seamless belt containing an inorganic filler and a fluororesin powder.
(3) The obtained seamless belt is peeled off from the cylindrical mold.
Below, each process is explained in full detail.

  When the polyamic acid solution is used, if the solution viscosity is high, the polyamic acid solution can be used by diluting with a suitable solvent to lower the viscosity. For example, the viscosity of the polyamic acid solution is set according to the coating thickness, coating method, coating conditions, solution temperature, etc., but is usually 10 to 10000 poise (B-type viscometer at the temperature (25 ° C.) during coating operation ( Rotor No. 7, viscosity measured at 4 rpm or 10 rpm)).

  In the above manufacturing method, any cylindrical mold can be used as a molding mold as long as it has been conventionally used in the production of seamless belts. Various types such as glass, ceramics and the like are exemplified.

  As a method for applying the polyamic acid solution (containing inorganic filler and fluororesin powder) to the cylindrical mold, the cylindrical mold is immersed in the polyamic acid solution to form a coating film on the inner surface, and this is used as a cylindrical die, etc. A method of forming a film by a method, a method in which a polyamic acid solution is supplied to one end portion of an inner surface of a cylindrical mold, and then a traveling body (bullet shape, spherical shape) having a certain clearance is traveled with the cylindrical mold. Examples include a method in which a mold is rotated around an axis, a polyamic acid solution is supplied to the inner surface, and a uniform film is formed by centrifugal force.

  In the above-described method of traveling the traveling body, as a method of traveling the traveling body, in addition to the self-weight traveling method (a method in which the cylindrical mold is set up vertically and the traveling body travels downward by its own weight), compressed air, Examples thereof include a method using a gas explosive force and a method using a pulling wire. The heating temperature after applying the polyamic acid solution is such that the solvent is removed by heating at a low temperature of about 80 to 200 ° C., the temperature is raised to about 250 to 400 ° C., and the imide conversion is terminated. It is done.

  In addition, the seamless belt that can be supported by the belt itself after low temperature heating is peeled off to form a primer layer or a fluororesin layer, and then high temperature heating may be performed. Although the time required for heating is appropriately set according to the heating time, both the low temperature heating and the subsequent high temperature heating are usually about 20 to 60 minutes. By using such a multi-stage heating method, it is possible to prevent the generation of minute voids in the seamless belt due to the ring-closing water and solvent evaporation generated with imide conversion.

  The seamless belt thus obtained is peeled from the cylindrical mold. As a method of peeling a polyimide resin seamless belt from a cylindrical mold, for example, a method of pressure-feeding air into a minute through-hole provided in advance on a peripheral wall surface of an end of a cylindrical mold can be cited. In addition, it is preferable to perform release treatment with a silicone resin or the like in advance on the inner peripheral surface of the cylindrical mold forming the seamless belt, which improves the peeling workability of the seamless belt.

  (Method of forming fluororesin release layer) As a method of forming a fluororesin release layer on the outer peripheral surface of the seamless belt, a method of depositing a tubular seamless belt obtained by melt extrusion on the outer surface of the tubular inner layer, solution It is formed by a method of covering the outer surface of the tubular inner layer with a shape (including dispersion). As a method for coating the solution-like fluororesin solution, for example, methods such as spray coating, spin coating, roll coating, and brush coating are conceivable.

  As a procedure for coating and heating, after applying a fluororesin release layer to prevent voids from being generated in the outer layer, the solvent in the fluororesin solution is removed, and then the temperature is raised above the melting point of the fluororesin. A fluororesin release layer can be formed. At this time, the imide conversion of the base layer seamless belt may be performed simultaneously.

(Features of seamless belt)
According to the seamless belt of the present invention, the wear resistance is improved and the generation of abrasion powder can be suppressed. Therefore, even if the image forming apparatus is enlarged and speeded up, quality deterioration due to abrasion powder on the belt can be suppressed. . Further, even when the seamless belt of the present invention is set as a fixing belt in a digital multi-function peripheral and used continuously at an increased printout speed, the generation of abrasion powder on the belt can be suppressed. Wrinkles can be prevented from occurring on the (transfer paper).
[Example]

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, evaluation in an Example etc. measured as follows. The present invention is not limited to the following examples.

(1) Surface roughness (Ra)
Measuring instrument: Surfcom 554A (Tokyo Seimitsu Co., Ltd.)
Measurement length: 4mm
Speed: 0.3mm / sec
Stylus load: 70mg
Cut-off: 0.8mm
Ra: arithmetic average roughness Friction coefficient measuring machine: Orientec AFT-15B
Mating material: φ10 steel ball Speed: 150 mm / min Load: 200 g

<Example 1>
(1) Fluororesin powder (PTFE; manufactured by Kitamura Co., Ltd., KTL-5) in N-methyl-2-pyrrolidone (NMP) and spherical silica having an average particle size of 5 μm (manufactured by Nippon Chemical Industry Co., Ltd., Product No. NS-05) ), And 41 g of p-phenylenediamine and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride are dissolved (solid content concentration: 20 wt%), and stirred at room temperature in a nitrogen atmosphere. The polyamic acid solution of 3000 poise (B-type viscometer, 25 ° C., rotor No. 7, 10 rpm) was obtained. At this time, the fluororesin powder was adjusted to 5 wt% in the polyimide resin composition, and the spherical silica was adjusted to 2 wt% in the polyimide resin composition.
(2) After applying the above polyamic acid solution to the inner surface of the cylindrical mold, the bullet-shaped traveling body was dropped by its own weight, and then defoaming was performed to remove bubbles in the coating film, thereby obtaining a uniform coating film surface. . Here, the difference between the inner diameter of the cylindrical mold and the maximum diameter of the bullet-like traveling body was 500 μm.
(3) Next, the mold was heated stepwise from 150 ° C. to remove the solvent, and then peeled from the mold at room temperature to obtain a seamless belt having a thickness of 50 μm.
(4) A fluorine coating solution was obtained by stirring a fluororesin (PFA; manufactured by Mitsui Deupon Fluoro Chemical Co., Ltd.) dispersion (solid content concentration: 35%) for 12 hours. The belt was coated with a primer and then coated with the fluorine coating solution.
(5) After that, it was inserted into a heat-resistant molding die and baked at 400 ° C. for 20 minutes, and the ring-closing water was removed and the imide conversion was completed. The roughness (Ra) of the inner surface of this belt was 0.12 μm.

(Fixing test)
The seamless belt obtained above was set in a driving test machine, and fixing was performed continuously at a speed of 25 rpm, and the generated abrasion powder was visually confirmed. As a result, although abrasion powder was generated at the 50,000th sheet, the operation was successful up to the target equivalent to 100k sheets.

<Example 2>
In the same manner as in Example 1, spherical silica was added to O.D. A belt with a fluorine coat was prepared in the same procedure as in Example 1 except that the amount was adjusted to 1% by weight and 0.5% by weight of the fluororesin powder in the polyimide resin composition. The roughness (Ra) of the inner surface of this belt was 0.08 μm. As a result of the fixing test similar to that of Example 1, although abrasion powder was generated at the 50,000th sheet, the apparatus operated without any problem up to the target equivalent to 100k sheet.

  <Example 3> The same procedure as in Example 1 was performed except that the spherical silica was adjusted to 10% by weight in the polyimide resin composition and the fluororesin powder was adjusted to 20% by weight in the polyimide resin composition. A belt with a fluorine coat was prepared in the same procedure as in Example 1. The roughness (Ra) of the inner surface of this belt was 0.25 μm. As a result of the fixing test similar to that of Example 1, although abrasion powder was generated at the 50,000th sheet, the apparatus operated without any problem up to the target equivalent to 100k sheet.

  <Comparative Example 1> A belt with a fluorine coat was produced in the same manner as in Example 2 except that spherical silica was not included in the polyamide solution (a belt having a fluororesin powder of 0.5% by weight in the polyimide resin composition). did. The roughness of the inner surface of this belt was 0.06 μm. As a result of the same fixing test as in Example 1, a lot of abrasion powder was generated on the 20,000th sheet, and wrinkle defects were generated on the 50th sheet.

  Comparative Example 2 A belt with a fluorine coat was prepared in the same manner as in Example 3 except that spherical silica was not included in the polyamide solution (a belt in which the fluorine resin powder was 20% by weight in the polyimide resin composition). The roughness of the inner surface of this belt was 0.2 μm. As a result of the same fixing test as in Example 1, abrasion powder was generated on the 30,000th sheet, and wrinkle defects occurred on the 87k sheet.

  <Comparative Example 3> The same procedure as in Example 1 was carried out except that the spherical silica was adjusted to 12 wt% in the polyimide resin composition and the fluororesin powder was adjusted to 20 wt% in the polyimide resin composition. A belt with a fluorine coat was prepared in the same procedure as in Example 1. The roughness of the inner surface of this belt was 0.46 μm. As a result of the same fixing test as in Example 1, the driving was heavy and the end cracks occurred.

Claims (3)

A seamless belt made of polyimide resin containing fluororesin powder and inorganic filler,
The fluororesin powder contains 0.5 to 20% by weight in the polyimide resin composition,
The spherical inorganic filler having an average particle diameter of 1 to 15 μm is contained in the polyimide resin composition in an amount of 0.1 to 10% by weight,
A seamless belt characterized in that the surface roughness Ra of the inner peripheral surface of the seamless belt is 0.06 to 0.6 μm. The spherical inorganic filler is
The seamless belt according to claim 1, wherein the seamless belt is one or a mixture of two or more selected from the group consisting of silica, alumina, quartz and aluminum nitride.   The seamless belt according to claim 1 or 2, further comprising a release layer made of a fluororesin on the outer periphery of the belt.