JP5101137B2 - Polyimide belt and manufacturing method thereof - Google Patents

Description

  The present invention relates to a polyimide 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.

  In recent years, copiers, printers, etc. have been remarkably colorized, large-sized images, and high-speed. Along with this, there is a tendency to widen the nip surface where the belt and roller come into contact with each other and to increase the surface pressure. It is sliding at high speed.

  Patent Document 1 discloses a belt in which a fluororesin powder is dispersed for the purpose of improving slidability.

  However, since the belt also wears from the inner surface, a large amount of wear powder is generated by the wear, and the belt may be deformed or broken. In this case, the favorable rotation of the belt is impaired, and specific problems include image formation defects such as rubbing toner and defects in which wrinkles occur on the image-formed paper.

  As a method for driving the belt, there are a method in which the roller that contacts contacts the driving force and a method in which the driving roller is arranged on the inner side. For example, the method for improving the slidability of the inner surface of the belt is not good for wear. However, when the driving roller is arranged on the inner side, it causes a slip. Therefore, there is a need for a method for preventing wear without changing the inner surface slidability of the belt.

Japanese Patent No. 2516310

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a polyimide belt excellent in slidability, a production method thereof, and the like that suppress the generation of wear powder.

  The inventors of the present invention have intensively studied to achieve the above-described object. As a result, the contact area is reduced by providing irregularities in a predetermined range on the inner surface of the belt, and the wear of the inner surface of the belt is not changed. The inventors have found that the generation of powder is suppressed, and have completed the present invention.

  That is, the polyimide belt of the present invention is characterized in that the inner surface roughness (Ra) of the belt is 0.15 to 0.6 [mu] m and the maximum surface roughness (Rmax) is 3 to 15 [mu] m. When the polyimide belt of the present invention is used in an electrophotographic image forming apparatus such as a copying machine, the generation of wear powder is suppressed, and the slidability and image formability are excellent.

The method for producing a polyimide belt of the present invention comprises a step of developing and heating a polyamic acid solution on the inner surface of a cylindrical mold A to obtain a polyimide belt by imide conversion;
Peeling the polyimide belt from the mold A and inserting the mold B having a surface roughness (Ra) of 2.5 to 10 μm and a maximum surface roughness (Rmax) of 15 to 45 μm into the polyimide belt When,
And a step of transferring the unevenness of the mold B to the inner surface of the polyimide belt by inserting heat or pressure after the mold B is inserted. The polyimide belt produced according to the present invention is excellent in slidability and image formability because generation of wear powder is suppressed when the belt is used in an electrophotographic image forming apparatus such as a copying machine.

The method for producing a polyimide belt of the present invention comprises a step of obtaining a cylindrical precursor belt that is cured until the polyamic acid solution is developed and heated on the inner surface of the cylindrical mold A and can be held as a belt;
The precursor belt is peeled from the mold A, and a mold B having a surface roughness (Ra) of 2.5 to 10 μm and a maximum surface roughness (Rmax) of 15 to 45 μm is inserted into the precursor belt. And a process of
A step of transferring the unevenness of the mold B onto the inner surface of the precursor belt by heating after inserting the mold B, and obtaining a polyimide belt by converting the precursor belt into an imide. And The polyimide belt produced according to the present invention is excellent in slidability and image formability because generation of wear powder is suppressed when the belt is used in an electrophotographic image forming apparatus such as a copying machine.

  The present invention relates to a polyimide belt obtained by the production method. The polyimide belt produced according to the present invention is excellent in slidability and image formability because generation of wear powder is suppressed when the belt is used in an electrophotographic image forming apparatus such as a copying machine.

  The composite belt of the present invention is characterized in that an elastic layer and / or a release layer are formed on the outer surface thereof. By having an elastic layer, there is no fear of deformation or buckling, and by having a release layer, a composite belt having good wear resistance, releasability with toner, and the like can be obtained.

  The composite belt of the present invention is characterized in that a primer layer and a release layer are formed on the outer surface thereof. The polyimide belt and the release layer are strongly bonded to each other through the plane layer, and a composite belt having excellent durability can be obtained.

  The polyimide belt of the present invention is characterized in that the inner surface roughness (Ra) of the belt is 0.15 to 0.6 [mu] m and the maximum surface roughness (Rmax) is 3 to 15 [mu] m. The inner surface of the polyimide belt in the present invention has a surface roughness (Ra) of 0.15 to 0.6 μm, preferably 0.2 to 0.4 μm. The maximum surface roughness (Rmax) is 3 to 15 μm, preferably 5 to 9 μm. When Ra is less than 0.15 μm and Rmax is less than 3 μm, the difference from the smooth surface is reduced and the effect of suppressing wear powder is reduced. On the other hand, if Ra exceeds 0.6 μm and Rmax exceeds 15 μm, it is not preferable because the inner surface is damaged or cannot be removed when the mold B is inserted or removed. Further, when Ra is large and Rmax is small, that is, when the difference in size of the unevenness is small, it is not preferable because the unevenness is not easily transferred.

  In the polyimide belt of the present invention, when uneven processing (transfer) is performed on the inner surface, since the surface of the mold B is gently transferred, a mold having unevenness larger than the target unevenness is inserted, and processing and adjustment are performed. It is preferable to do. Specifically, the surface roughness (Ra) is preferably 2.5 to 10 μm, more preferably 3.5 to 8 μm. The maximum surface roughness (Rmax) is preferably 15 to 45 μm, more preferably 20 to 30 μm. In addition, this uneven | corrugated process exists in the inner surface whole surface of a belt, and it is not necessary to have a pattern in particular.

  When surface smoothness is required on the outer surface of the belt of the present invention, for example, it is preferable to select a fluorine-coated fixing belt having relatively small irregularities, and surface smoothness on the outer surface of the belt is required. If not, for example, a fixing belt having an elastic body on the outer surface of the belt and a release layer such as a tube on the outer periphery thereof may be selected even if it has relatively large irregularities.

  The polyimide belt of the present invention has a predetermined surface roughness and a maximum surface roughness. As a specific method for producing a polyimide belt, a polyamic acid solution is prepared by dissolving and polymerizing a tetracarboxylic dianhydride or a derivative thereof (tetracarboxylic acid component) and a diamine component, which are raw materials of a polyimide resin. Further, a polyimide acid solution is prepared by spreading and heating the polyamic acid solution on the inner surface of the mold to convert it into an imide.

(Raw material of polyimide belt)
The polyimide belt of the present invention contains a polyimide resin as a main component. Here, the “main component” is a main component constituting the polyimide resin composition, and means that it greatly affects the properties of the composition.

  Examples of the raw material for the polyimide resin include polyamic acid which is a precursor thereof. This polyamic acid can be obtained by reacting approximately equimolar amounts of a tetracarboxylic acid component and a diamine component in an organic solvent.

  Examples of the tetracarboxylic acid component include those represented by the following general formula (1).

［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 acid component include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetra. Carboxylic dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic Acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ) Sulfonic acid dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylenetetracarboxylic dianhydride, etc. It is.

Specific examples of the diamine component to be reacted with such a tetracarboxylic acid component include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, and 3,3′-dichloro. Benzidine, 4,4'-diaminodiphenyl sulfide-3,3'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3'-dimethyl-4,4'-biphenyl Diamine, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 4,4′-diaminophenylsulfone, 4,4′-diaminodiphenylsulfide, 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-methyl Heptamethylenediamine, 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 the above tetracarboxylic acid components and diamine components can be appropriately selected and reacted.

  The organic polar solvent used when the tetracarboxylic acid component and the diamine component are reacted has a dipole whose functional group does not react with 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. They 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, dimethylsulfoxide, 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.

(Polyimide belt manufacturing method)
The polyimide belt of the present invention is obtained by completing the removal of the solvent of the polyamic acid solution by heating, the removal of dehydrated ring-closing water, and the imide conversion.

The imide conversion may be carried out either by a method using high temperature heating or a method in which polyamic acid is used alone or in combination with a catalyst and a dehydrating agent, and is not particularly limited as long as it meets the object of the present invention.

Below, an example (I) is shown as a manufacturing method of the polyimide belt of this invention.
(1) Step of preparing a polyamic acid solution (2) Step of coating the prepared polyamic acid solution on the inner surface of the cylindrical mold A, developing and heating to perform imide conversion (3) A polyimide belt after imide conversion Step of peeling and removing from cylindrical mold A (4) Step of transferring mold irregularities of mold B by inserting mold B having predetermined irregularities into the taken out polyimide belt and applying heat or pressure

  Below, the process of the said manufacturing method (I) is explained in full detail.

(Preparation process of polyamic acid solution)
The polyamic acid solution is preferably obtained by reacting the tetracarboxylic acid component (x) and the diamine component (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.

  Further, when the tetracarboxylic acid component and the diamine component are reacted in the organic polar solvent in this way, the viscosity of the solution increases as the reaction proceeds. In the present invention, the logarithmic viscosity (η) is 0. It is preferable to use a polyamic acid solution 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.

［ｔ_０：溶媒の落下速度、ｔ_１：溶液の落下速度、Ｃ：溶液の濃度（ｇ／ｄｌ）］

[T ₀ : solvent falling speed, t ₁ : solution falling speed, C: solution concentration (g / dl)]

  When the above-mentioned polyamic acid solution has a high viscosity, it is diluted with an appropriate solvent to reduce 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 1 to 1000 Pa · s (the B-type viscometer at the temperature during the coating operation). Measured at).

  The belt of the present invention is substantially made of a polyimide resin, and is appropriately filled according to various purposes such as thermal conductivity, conductivity, antistatic property, semiconductivity, high slidability, high strength, and high elasticity and its use. An agent may be added. The addition amount of the filler can be appropriately set according to the purpose within the scope of the present invention.

  For example, when the above-mentioned polyamic acid is prepared, the filler is mixed and dispersed in the solution with an appropriate dispersing machine such as a planetary mixer, a bead mill, or a three-roll. Then, they can be mixed and blended, and can be carried out by an appropriate method such as a method of subjecting it to film forming. Of course, after completion of the reaction, each may be added to the polyamic acid solution and mixed uniformly.

  As described above, the polyimide belt can be obtained by appropriately developing and heating the polyamic acid solution. The thickness of the belt can be appropriately determined according to the purpose of use. In general, the thickness is preferably 5 to 250 μm, more preferably 20 to 150 μm, and still more preferably 40 to 100 μm, in view of mechanical properties such as strength and flexibility.

(Imide conversion)
As a process for performing imide conversion, first, a cylindrical mold A is prepared as a molding mold, and a polyamic acid solution is applied to the inner surface of the mold A. After coating, the coating film is heated and cured, and heated until imide conversion is completed, thereby forming a polyimide belt.

  As a method for applying the polyamic acid solution to the mold A, the mold A is immersed in the polyamic acid solution to form a coating film on the inner surface, and this is formed with a cylindrical die or the like. After supplying the polyamic acid solution to one end portion of the inner surface, a method of traveling the mold A and a traveling body (bullet-shaped, spherical) having a certain clearance, rotating the mold A around the axis, and polyamic acid on the inner surface Examples include a method of supplying a solution and forming a uniform coating film by centrifugal force.

  In the above-described method of traveling the traveling body, the traveling body can be traveled by a self-weight traveling method (a method in which the mold A is set up vertically and the traveling body travels downward by its own weight), compressed air or gas. A method using explosive force, a method using a pulling wire, etc.

  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., and then the temperature is raised to about 250 to 400 ° C. to complete the imide conversion. Is used.

  Although the said heating time is suitably set according to heating time, both low temperature heating and subsequent high temperature heating are about 20 to 60 minutes normally. By using such a multi-stage heating method, it is possible to prevent the generation of minute voids in the belt due to the ring-closing water and solvent evaporation generated with imide conversion.

  In the above manufacturing method, as the cylindrical mold A to be a molding mold, any material can be used as long as it is conventionally used for manufacturing a seamless belt, and the material is from the viewpoint of heat resistance. Various types such as metal, glass and ceramics are exemplified.

(Peeling process)
The polyimide belt obtained as described above is peeled off from the mold A. As a method of peeling the polyimide belt from the mold A, for example, a method of pressure-feeding air to a minute through-hole provided in advance on the peripheral wall surface of the end of the mold can be used. Note that it is preferable to perform a release treatment with a silicone resin or the like on the inner surface of the mold A forming the seamless belt in advance, so that the belt peeling workability is improved.

(Uneven transfer process)
A mold B having predetermined unevenness is inserted into the polyimide belt, and heated or hot pressed at about 300 to 420 ° C. to transfer the unevenness of the mold B. By this step, a polyimide belt having a predetermined surface roughness can be obtained.

Below, (b) is shown as an example of a method for producing a polyimide belt other than the production method (A).
(1) Step of preparing a polyamic acid solution (2) Step of forming a precursor belt in which the prepared polyamic acid solution is applied to the inner surface of the cylindrical mold A, spread and heated, and cured until it can be held as a belt (3) Step of peeling and removing the precursor belt from the mold A (4) Inserting a mold B having predetermined irregularities into the removed precursor belt and heating the precursor belt, the irregularities of the mold B And transferring the imide and heating the precursor belt

  Below, the specific process in a manufacturing method (b) is explained in full detail.

(Precursor belt manufacturing process)
A cylindrical mold A is prepared as a molding mold, and a polyamic acid solution is applied to the inner surface of the mold A. After coating, the precursor belt is formed by heating and curing until the coating film can be supported at least by itself. The heating temperature is about 90 to 160 ° C., and the solvent is removed by heating to obtain a precursor belt.

(Uneven transfer process and imide conversion)
A mold B having predetermined irregularities is inserted into the precursor belt, heated at a low temperature of about 150 to 200 ° C., and then heated to about 300 to 420 ° C. to complete imide conversion, etc. It is done. By this step, the unevenness of the mold B can be transferred together with the imide conversion, and a polyimide belt having a predetermined surface roughness can be obtained. Alternatively, the precursor belt that can be supported by the belt itself after low-temperature heating is peeled off to form a release layer, an elastic layer, and a primer layer, which will be described later, and then high-temperature heating may be performed.

(Composite belt)
An elastic layer, a release layer, a primer layer, and the like can be formed on the outer surface of the polyimide belt of the present invention to form a composite belt. Specifically, it is obtained by forming an elastic layer and / or a release layer on the outer surface of the polyimide belt. Further, it can be obtained by forming a primer layer and a release layer on the outer surface of the polyimide belt.

(Release layer)
A release layer can be formed on the outer surface of the polyimide belt of the present invention. As the method, it is formed by a method of coating a tubular seamless belt obtained by melt extrusion on the outer surface of the tubular inner layer, a method of coating a solution-like resin (including dispersion) on the outer surface of the tubular inner layer, or the like.

  Examples of the method for coating the solution-like resin include spray coating, spin coating, roll coating, brush coating, dipping, and dispenser coating. As a procedure of coating and heating, in order to prevent voids from being generated in the outer layer, after applying a solution-like resin, the solvent is removed and the temperature is raised to the melting point of the resin or more to form a release layer. it can. At this time, the mold B adjusted to a predetermined surface may be inserted to simultaneously transfer the shape of the inner surface and imide conversion.

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

(Elastic layer)
In addition, an elastic layer can be formed on the outer surface of the polyimide belt. Examples of the method include spiral application with a dispenser, spray coating, dipping, and the like.

  The raw material for the elastic layer can be appropriately selected from natural rubber, synthetic rubber, silicone rubber, and the like. It is also possible to impart releasability to the elastic layer.

  In the present invention, after the polyimide belt is molded, an elastic layer and a release layer may be stacked on the outer side, or the release layer, the elastic layer, and the polyimide are laminated on the inner surface of the mold in this order. It is also possible to take a step of removing from the mold after conversion. These processes can be freely selected according to the dimensional accuracy, characteristics and molding cost of the belt.

(Primer layer)
Moreover, in order to reinforce the adhesive force between the elastic layer and the release layer, a primer layer may be provided in the middle. Further, the release layer may be laminated by covering the elastic layer on the elastic layer and then shrinking by heating.

  In addition, a primer layer can be formed between the polyimide belt and the release layer.

  As the primer layer, various commercially available primers that enhance the adhesion between the belt and the release layer can be used, and a polyimide-based primer is preferably used for the polyimide belt.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below.

<Evaluation method>
(1) Surface roughness (Ra) and maximum surface roughness (Rmax)
The measurement was performed under the following conditions.
Measuring instrument: SJ-301 (Mitutoyo)
Measurement length: 5mm x 5 (5mm section is measured 5 times)
Speed: 0.25mm / sec
Cut-off: 0.8mm

(2) Operation Test As an operation test, evaluation was performed by replacing a fixing belt of a trade name: Docu Print C2220 (manufactured by Fuji Xerox Co., Ltd.) with a polyimide belt of Examples and Comparative Examples. Those capable of operating more than 80,000 sheets were evaluated as “good”, and those less than 80,000 were evaluated as “x”.

<Example 1>
In 611 g of N-methyl-2-pyrrolidone, 41 g of p-phenylenediamine and 112 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride are dissolved (solid content concentration 20% by weight) in a nitrogen atmosphere. After reacting while stirring at room temperature, the viscosity was adjusted at 75 ° C. to obtain a 300 Pa · s polyamic acid solution. The above polyamic acid solution is applied to the inner surface of a cylindrical mold A having an inner diameter of 30 mm and a length of 600 mm, and the bullet-like traveling body is dropped by its own weight, and then defoaming is performed to remove bubbles in the precursor belt. A precursor belt surface was obtained.

  Next, the mold A was heated stepwise from 150 ° C. to 220 ° C. to remove the solvent, and then peeled off from the mold A at room temperature to obtain a polyimide belt having a thickness of 80 μm. Insert aluminum mold B with surface roughness adjusted to Ra 5μm and Rmax 30μm, heat at 400 ° C for 20 minutes, remove ring-closing water, complete imide conversion reaction, and produce the prescribed polyimide belt did. The roughness of the inner surface of this belt was Ra 0.2 μm and Rmax 6.5 μm. This was set in a driving tester and fixed continuously. The target 80,000 sheets were operated without any problems.

<Example 2>
A polyimide belt having a thickness of 80 μm was produced in the same manner as in Example 1 except that the mold B having the surface adjusted to Ra 2.5 μm and Rmax 15 μm was used in the same manner as in Example 1. The roughness of the inner surface of this belt was Ra 0.15 μm and Rmax 3 μm. The target 80,000 sheets were operated without any problems.

<Example 3>
A polyimide belt having a thickness of 80 μm was produced in the same manner as in Example 1 except that the mold B having the surface adjusted to Ra 10 μm and Rmax 45 μm was used in the same manner as in Example 1. The roughness of the inner surface of this belt was Ra 0.6 μm and Rmax 15 μm. The target 80,000 sheets were operated without any problems.

<Example 4>
The method is the same until the application to the mold A in Example 1, and the heating method is to heat the mold A from 150 ° C. to 380 ° C. in steps to remove the solvent, and then peel from the mold A at room temperature. As a result, a polyimide belt having a thickness of 80 μm was obtained. Thereafter, a mold B whose surface was adjusted to Ra 2.5 μm and Rmax 15 μm was inserted and heated again at 420 ° C. for 15 minutes to prepare a predetermined polyimide belt. The roughness of the inner surface of this belt was Ra 0.15 μm and Rmax 3 μm. The target 80,000 sheets were operated without any problems.

<Comparative Example 1>
A polyimide belt was produced in the same procedure as in Example 1 except that the mold B whose surface was adjusted to Ra 1.5 μm and Rmax 10 μm was used. The roughness of the inner surface of this belt was Ra 0.1 μm and Rmax 1.5 μm. A large amount of wear powder was generated and slipped at about 50,000 sheets, resulting in rotation failure and wrinkle failure.

<Comparative example 2>
The production of the polyimide belt was tried in the same procedure as in Example 1 except that the mold B whose surface was adjusted to Ra 13 μm and Rmax 50 μm was used. However, it was difficult to remove the belt after heating to complete the imide conversion. Because the inner surface was deeply scratched, it was abandoned to be evaluated.

<Table 1> Evaluation results

  From the results shown in Table 1, it was confirmed that good results could be obtained in the operation test in Examples in which the surface roughness (Ra) and the maximum surface roughness (Rmax) of the polyimide belt were within the predetermined ranges. On the other hand, when Ra and Rmax of the polyimide belt were outside the predetermined range as in Comparative Example 1, a large amount of wear powder was generated, resulting in inconvenience in the operation test. Further, in Comparative Example 2, when the Ra and Rmax of the mold were out of the predetermined range, it was difficult to remove the belt itself, and the operation test itself could not be performed.

Claims (5)

Developing and heating the polyamic acid solution on the inner surface of the cylindrical mold A to convert the imide to obtain a polyimide belt;
Peeling the polyimide belt from the mold A and inserting the mold B having a surface roughness (Ra) of 2.5 to 10 μm and a maximum surface roughness (Rmax) of 15 to 45 μm into the polyimide belt When,
After inserting the mold B, step thermal pressure or to transfer the irregularities of the mold B on the inner surface of the polyimide belt by heating, city only contains,
A method for producing a polyimide belt, wherein the belt inner surface has a surface roughness (Ra) of 0.15 to 0.6 [mu] m and a maximum surface roughness (Rmax) of 3 to 15 [mu] m . A step of obtaining a cylindrical precursor belt cured until the polyamic acid solution can be developed and heated on the inner surface of the cylindrical mold A and held as a belt;
The precursor belt is peeled from the mold A, and a mold B having a surface roughness (Ra) of 2.5 to 10 μm and a maximum surface roughness (Rmax) of 15 to 45 μm is inserted into the precursor belt. And a process of
After inserting the mold B, to obtain a polyimide belt by imidization of the precursor belt with transferring the unevenness of the mold B on the inner surface of the precursor belt by heating, city only contains,
A method for producing a polyimide belt, wherein the belt inner surface has a surface roughness (Ra) of 0.15 to 0.6 [mu] m and a maximum surface roughness (Rmax) of 3 to 15 [mu] m . A polyimide belt obtained by the production method according to claim 1. The composite belt which forms an elastic layer and / or a mold release layer in the outer surface of the polyimide belt of Claim 3 . A composite belt in which a primer layer and a release layer are formed on the outer surface of the polyimide belt according to claim 3 .