JP4798853B2 - Seamless belt and manufacturing method thereof - Google Patents

Description

[0001]
[Technology to which the invention belongs]
The present invention relates to a seamless belt of an electrophotographic image forming apparatus and a method for manufacturing the same. More specifically, the present invention relates to a fixing conveyance belt, a transfer fixing belt used in an electrophotographic copying machine, a printer, a facsimile, and the like, and a manufacturing method thereof.
[0002]
[Prior art]
Conventionally, rolls and drums have been used as rotating members for electrophotographic image forming apparatuses.
[0003]
In recent years, plastic belts have been put into practical use in place of these members in order to solve the downsizing of the apparatus. As belts used for such applications, seamless belts made of thermoplastic resins such as polycarbonate and ethylenetetrafluoroethylene copolymer are known (Japanese Patent Laid-Open Nos. 10-10880 and 2000-25097). ).
[0004]
However, since the thermoplastic resin has low heat resistance and durability, and is manufactured by a method such as die extrusion, the belt used in the electrophotographic image forming apparatus has low dimensional accuracy such as thickness accuracy and surface accuracy. As such, it was not satisfactory for being put to practical use.
[0005]
On the other hand, a seamless belt for an image forming apparatus made of a thermosetting polyimide resin has been proposed. As a method for producing these seamless belts, after applying a polyimide precursor solution to a core, removing the solvent and performing an imide conversion reaction, coating the polyimide precursor solution on the inner surface of a cylindrical mold After the formation, a method of intermittently removing the solvent and imide conversion as it is, and after forming the coating by applying the polyimide precursor solution to the inner surface of the cylindrical mold, a part of the solvent until the coating can support itself And removal of the solvent and partial imide conversion, and then peeling from the mold and replacing with a tubular mold to remove the solvent and complete the imide conversion reaction.
[0006]
[Problems to be solved by the invention]
However, in these methods, when the solvent is completely removed and the imide conversion reaction is completed, the solvent of the polyimide precursor solution and the ring-closing water are trapped between the belt and the mold supporting the belt, which causes the swelling of the belt. There is a problem of causing unevenness. On the other hand, as means for solving this, a proposal has been made to provide a large number of fine through holes around a tubular mold (Japanese Patent Laid-Open No. 10-258434). However, such fine through-holes cause variations in characteristics such as the inner surface and film thickness of the seamless belt. In addition, since the tubular mold itself is held in the high-temperature furnace for a long time, the strength of the mold itself is insufficient compared to the tubular mold without a through-hole, resulting in bending of the mold, and thus the difference in inner diameter and outer diameter of the seamless belt. In addition to causing dimensional defects such as the occurrence of the above, it causes a decrease in accuracy of the inner peripheral surface of the seamless belt.
[0007]
On the other hand, such a seamless belt has a nip portion that presses the seamless belt against a heating drive roll disposed opposite to the belt outer side with a pressing member disposed on the inner side thereof, and allows a recording material to pass through the outer surface of the belt. And a fixing device in which a sliding material is disposed on the sliding surface of the pressing member, and a lubricant is interposed between the pressing member and the inner surface of the belt so that the belt can run. . Since this fixing device is driven while being pressed by a heating drive roll arranged outside the belt, the friction coefficient of the inner surface must always be lower than the friction coefficient of the outer surface of the belt. An agent is interposed. However, if the surface accuracy of the inner surface of the seamless belt is low, the supply of lubricant from the lubricant supply means is not stable, and the transportability of the belt becomes unstable.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide a seamless belt which has few dimensional defects, has a good surface accuracy on the inner peripheral surface and has no unevenness, and a method for manufacturing the same.
[0009]
[Means for Solving the Problems]
The object can be achieved by the present invention as described below. That is, the seamless belt of the present invention forms a nip portion that allows the recording material to pass through the outer surface of the seamless belt by pressing the heating drive roll disposed facing the outer side with the pressing member disposed on the inner side. A seamless belt capable of running with a lubricant interposed between the sliding material and the inner surface of the seamless belt while disposing a sliding material on the sliding surface of the pressing member, the inner surface of the seamless belt The roughness is characterized in that Rmax is 0.18 to 8.00 μm, Rz is 0.10 to 3.50 μm, and Ra is 0.02 to 0.50 μm.
[0010]
The seamless belt of the present invention is used for a fixing device or the like in an image forming apparatus, and is used, for example, in a mode as shown in FIG.
[0011]
In FIG. 1, a pressing member 2 is disposed inside the seamless belt 1, and a heating drive roll 3 is disposed outside the seamless belt 1 so as to face the pressing member 2. The heating drive roll 3 has a built-in heating source 31 such as a halogen lamp. The seamless belt 1 is pressed against the heating drive roll 3 by the pressing member 2 to form the nip portion 4 outside the seamless belt 1. The nip portion 4 is a portion through which the recording material 5 passes when the seamless belt 1 travels as the heating drive roll 3 rotates. The recording material 5 to which the thermal ink 51 is temporarily attached has its image fixed by heating and pressing during passage. In order for the seamless belt 1 to travel stably, it is necessary to reduce the friction coefficient of the inner surface of the belt. For this purpose, a sliding member 6 is disposed on the sliding surface of the pressing member 2, and a lubricant is interposed between the sliding member 6 and the inner surface of the seamless belt 1.
[0012]
Here, the sliding material refers to a material that reduces the coefficient of friction with the inner surface of the seamless belt 1, and examples thereof include a fluororesin sheet or the like, a glass fiber sheet or the like coated with a fluororesin, and the like.
[0013]
Examples of the lubricant include silicone oil, modified silicone oil such as amino-modified silicone oil, carboxy-modified silicone oil, and sulfonic acid-modified silicone oil. The lubricant can be supplied manually or automatically using a conventionally known method, apparatus, or the like.
[0014]
In order to stably supply the lubricant and keep the transportability of the seamless belt good, the surface roughness (Ra) of the inner surface of the seamless belt is 0.02 to 0.5 μm, preferably 0.03 to 0.03. 0.4 μm, more preferably 0.04 to 0.2 μm. The surface roughness (Rz) of the belt is 0.1 to 3.5 μm, preferably 0.2 to 3.0 μm. The surface roughness (Rmax) of the belt is 0.18 to 8.00 [mu] m, preferably 0.2 to 7.00 [mu] m.
[0015]
The surface roughness (Ra, Rz and Rmax) is defined in JIS B 0601, and is a value measured by the method shown in the examples.
[0016]
The method for producing a seamless belt of the present invention is a method suitably used for producing the seamless belt of the present invention. That is, the manufacturing method includes a step of applying a polyimide precursor solution to a mold, curing it by heating and drying until it can be self-supported, and peeling it from the mold to obtain a polyimide precursor belt, from the inner diameter of the polyimide precursor belt A step of inserting a support having a smaller outer diameter into the polyimide precursor belt, a step of heating the polyimide precursor belt together with the support to complete the imide conversion reaction, and taking out the seamless belt from the support The surface roughness of the support is 1.4 to 50.0 μm, Rz is 1.0 to 40.0 μm, and Ra is 0.1 to 5.0 μm. It is.
[0017]
The surface roughness (Ra) of the support is such that residual solvent or ring-closing water that evaporates during heating does not stay between the support and the belt, and the unevenness of the support surface affects the surface properties of the inner surface or outer surface of the seamless belt. In order not to give, it is 0.1-5.0 micrometers, Preferably it is 0.3-4.0 micrometers, More preferably, it is 0.5-3.0 micrometers. Similarly, the surface roughness (Rz) of the support is 1.0 to 40.0 μm, preferably 2.0 to 35.0 μm. Similarly, the surface roughness (Rmax) of the support is 1.4 to 50.0 μm, preferably 3.0 to 45.0 μm.
[0018]
The surface roughness (Ra, Rz and Rmax) is defined in JIS B 0601, and is a value measured by the method shown in the examples.
[0019]
In the manufacturing method of this invention, it is preferable that the thermal expansion coefficient of the said support body is larger than the thermal linear expansion coefficient of the said polyimide precursor belt. In this case, since the support is heat-set while pressing the seamless belt from the inside during heating, a seamless belt having even better dimensional accuracy and surface characteristics can be obtained. Conversely, if the coefficient of thermal expansion is small, the gap between the support and the polyimide precursor belt will widen during heating, and the residual solvent and ring-closing water will efficiently evaporate from the inner surface of the belt. I can't.
[0020]
The thermal expansion coefficient of the polyimide resin is generally 1 × 10 ^{−5 to} 3 × 10 ⁻⁵ cm / cm / ° C., although it varies depending on the amount of residual solvent and the polyimide composition constituting the belt. Therefore, the thermal linear expansion coefficient of the support is usually preferably larger than the thermal linear expansion coefficient of the polyimide resin, more preferably 2 × 10 ⁻⁵ cm / cm / ° C. or more, and even more preferably 3 × 10 ⁻⁵ cm. / Cm / ° C. or higher.
[0021]
The thermal expansion coefficient is a value measured according to JIS K 7197.
[0022]
Examples of the material for the support that satisfies the above requirements include metals such as copper, aluminum, magnesium, zinc, and manganese, alloys thereof, glass, and ceramics.
[0023]
[Function and effect]
The seamless belt of the present invention has few dimensional defects, good surface accuracy on the inner peripheral surface and no unevenness, and can be suitably used as a seamless belt such as a fixing belt and a transfer fixing belt in an image forming apparatus. Moreover, according to the manufacturing method of this invention, such a seamless belt can be manufactured efficiently.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail below.
[0025]
The seamless belt of the present invention is a process in which a polyimide precursor solution is applied to a mold, cured until it can be self-supported by heat drying, and peeled off from the mold to obtain a polyimide precursor belt, the inner diameter of the polyimide precursor belt A step of inserting a support having a smaller outer diameter into the polyimide precursor belt, a step of heating the polyimide precursor belt together with the support to complete the imide conversion reaction, and a seamless belt from the support. It is manufactured by a method including a step of taking out.
[0026]
The polyimide precursor solution used for this invention is obtained by making an acid dianhydride component and a diamine component react in a solvent. Examples of the acid dianhydride component 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-naphthalenetetracarboxylic dianhydride, 4,5,8-naphthalenetetracarboxylic dianhydride and the like.
[0027]
On the other hand, as the diamine component, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3, 3'-diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3'-dimethyl-4,4'-biphenyldiamine, benzidine, 3,3'-dimethylbenzidine, 3 , 3′-dimethoxybenzidine, 4,4′-diaminodiphenylsulfone and the like.
[0028]
An appropriate solvent can be used as the solvent for the polymerization reaction of these acid dianhydrides and diamine, but organic polar solvents are preferably used from the viewpoint of solubility and the like, and N, N-dialkylamides are preferable. Specifically, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphotriamide, N -Methyl-2-pyrrolidone, pyridine, dimethyl sulfoxide, tetramethylene sulfone, dimethyl tetramethylene sulfone and the like can be mentioned, and these can be used alone or in combination.
[0029]
A polyimide precursor solution is obtained by polymerizing the acid dianhydride component and the diamine component in an organic polar solvent. The monomer concentration (acid dianhydride component and diamine component in the solvent) at that time is set according to various conditions, but is preferably 5 to 30% by weight. The reaction temperature is preferably set to 80 ° C. or less, and the reaction time is preferably 0.5 to 10 hours.
[0030]
Since the solution viscosity increases as the polymerization reaction proceeds, the viscosity can be adjusted. Also, the viscosity can be adjusted by the monomer concentration. Specifically, the viscosity is preferably 10 to 10000 poise, and more preferably 50 to 8000 poise.
[0031]
In the polyimide precursor solution in the present invention, a filler is appropriately added depending on various purposes such as thermal conductivity, conductivity, antistatic property, semiconductivity, high slidability, high strength, and high elasticity and its use. May be. For example, heat conductive inorganic powder such as aluminum nitride, boron nitride, alumina, silicon carbide, silicon carbide, silica, etc., conductive or semiconductive powder such as carbon black, aluminum, nickel, tin oxide, potassium titanate, Polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) fluororesin, and the like. The filling amount of the filler can be determined according to the purpose within the scope of the present invention.
[0032]
The polyimide precursor solution is applied to a mold. Any mold may be used as long as it has been conventionally used in the production of seamless belts. Usually, a cylindrical mold corresponding to the shape of the belt is used and applied to the inner surface thereof. As a method of uniformly applying to a cylindrical mold, a known method can be applied, and examples thereof include a method of centrifugal molding, a method of applying by a dispenser, a method of using a scraper, and a method of using a bullet-like traveling body. It is done. Examples of the material of the mold include various materials such as metal, glass, and ceramic from the viewpoint of heat resistance.
[0033]
The polyimide precursor solution uniformly applied on the cylindrical mold in this way is cured by heating until it can be self-supported, and then the polyimide precursor belt is peeled from the mold. The heating temperature is not particularly limited as long as it can evaporate the applied solvent, and can be appropriately set. In order to prevent generation of microvoids due to rapid evaporation of the solvent in the polyimide precursor solution, it is preferably 230 ° C. or lower, and preferably 80 ° C. or higher from the viewpoint of shortening the heating time. The heating time is appropriately set according to the heating temperature, and is usually about 10 to 60 minutes.
[0034]
Examples of the method for peeling the polyimide precursor belt from the cylindrical mold include a method in which air is pumped into a minute through hole provided in advance on the peripheral wall of the mold end. In addition, it is preferable to perform a mold release treatment with a silicone resin or the like on the circumferential surface of the cylindrical mold in advance because the workability of peeling the polyimide precursor belt is improved.
[0035]
In the present invention, a support having an outer diameter smaller than the inner diameter is inserted into the polyimide precursor belt obtained as described above, and then the polyimide precursor belt is heated together with the support to remove residual solvent. Removal, removal of ring-closing water, and completion of imide conversion reaction.
[0036]
The heating temperature at this time is preferably equal to or higher than the heating temperature on the cylindrical mold from the viewpoint of removal of residual solvent and ring-closing water, and 400 from the viewpoint of heat resistance and thermal linear expansion coefficient of the polyimide precursor belt and the support. C. or lower is preferable. Usually, the heating time at this time is 10 to 60 minutes.
[0037]
Of course, it is necessary to appropriately set the dimensions of the support so that the support has a difference in inner diameter and outer diameter that is preferable as a seamless belt according to the purpose.
[0038]
The belt obtained as described above is taken out from the support. Usually, the substrate is allowed to cool at room temperature and then taken out after the support is thermally contracted.
[0039]
Furthermore, in the present invention, when the polyimide precursor belt is supported on the support, or when the seamless belt obtained by heating is supported on the support, the releasability, elasticity, and photoconductivity. In order to provide further functions such as PTFE, FEP, and PFA, fluorine resin such as PTFE, silicone rubber, or fluorine rubber may be further laminated on the outer peripheral surface of the belt by a method such as spray coating or dipping. When used as a heat generating belt of an electromagnetic induction heat generation method, an electromagnetic induction heat generation layer made of nickel, iron, cobalt, copper, aluminum, or an alloy thereof may be provided by using a method such as plating or ion plating. Good.
[0040]
【Example】
Examples and the like specifically showing the configuration and effects of the present invention will be described below.
[0041]
[Example 1]
In 732 g of N-methyl-2-pyrrolidone, 147 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 54 g of p-phenylenediamine were dissolved (solid content concentration 20% by weight), and in a nitrogen atmosphere The mixture was reacted at room temperature with stirring to obtain a 3000 poise polyimide precursor solution. After the polyimide precursor solution is applied to the inner surface of a cylindrical mold having an inner diameter of 40 mm, the bullet-shaped traveling body is dropped by its own weight, and then the degassing method is performed to remove bubbles in the coating film to obtain a uniform coating film surface. It was. The mold was then heated from room temperature to 180 ° C. for 30 minutes and cured (partially solvent removal and partial imide conversion) until it could be held as a belt itself to obtain a polyimide precursor belt. After releasing the belt from the mold, the surface roughness Ra is 2.5 μm, Rz is 20.0 μm, Rmax is 27.0 μm, and the thermal expansion coefficient is 2.6 × 10 ⁻⁵ cm / cm / ° C. It was replaced with a certain metallic cylindrical support, and the support was heated to 370 ° C. at a temperature increase rate of 2 ° C./min to remove residual solvent and ring-closing water, complete the imide conversion reaction, and then cooled. A seamless belt made of polyimide having a thickness of 60 μm was obtained. After the primer treatment is performed on the outer surface of the seamless belt on the metallic support, a PFA aqueous dispersion is spray-coated as a release resin, and then heated to 370 ° C. while being inserted into the support, and then cooled. A seamless belt (total thickness: 71 μm) having a releasable resin layer of 10 μm was obtained.
[0042]
As for the surface roughness of the inner surface of this belt, Ra was 0.2 μm, Rz was 2.3 μm, and Rmax was 3.7 μm, and no swelling or poor appearance due to the accumulation of solvent was observed. When this belt was tested with an actual fixing device, the belt was well conveyed and a good fixed image was obtained (a toner fixing reduction rate of 4%).
[0043]
[Example 2]
In Example 1, the surface roughness of the metal cylindrical support was changed to Ra of 3.0 μm, Rz of 30.0 μm and Rmax of 40.0 μm, in the same manner as in Example 1, with a polyimide layer thickness of 60 μm, A seamless fixing belt (total thickness: 71 μm) having a release resin layer thickness of 10 μm was obtained.
[0044]
As for the surface roughness of the inner surface of this belt, Ra was 0.3 μm, Rz was 3.0 μm, and Rmax was 6.0 μm, and no swelling or poor appearance due to the accumulation of solvent was observed. When this belt was tested with an actual fixing device, the belt was well conveyed and a good fixed image was obtained (7% reduction in toner fixing), and functioned without problems after 3 weeks.
[0045]
[Comparative Example 1]
In Example 1, the surface roughness of the metal cylindrical support was changed to Ra 7.0 μm, Rz 42.0 μm and Rmax 60.0 μm in the same manner as in Example 1 except that the polyimide layer thickness was 60 μm. A seamless fixing belt (total thickness: 73 μm) having a releasable resin layer thickness of 12 μm was obtained.
[0046]
The surface roughness of the inner surface of this belt was 0.6 μm for Ra, 4.0 μm for Rz, and 9.0 μm for Rmax, but when this belt was put on an actual fixing device, the fixing property was poor (toner Therefore, the fixed image was unclear.
[0047]
[Comparative Example 2]
In Example 1, the surface roughness of the metal cylindrical support was 0.05 μm for Ra, 0.80 μm for Rz, and 1.00 μm for Rmax, and the thickness of the polyimide layer was 60 μm in the same manner as in Example 1. A seamless fixing belt (total thickness: 73 μm) having a releasable resin layer thickness of 12 μm was obtained, but swelling occurred due to the accumulation of solvent between the inner surface of the belt and the support. The difference in outer diameter of the swollen portion was 1%. The inner surface of the belt had Ra of 0.01 μm, Rz of 0.07 μm and Rmax of 0.15 μm. Even when the obtained seamless belt was applied to the fixing device, the transportability was poor from the beginning, and it could not be put into practical use.
[0048]
[Comparative Example 3]
In Example 1, the surface roughness of the metal cylindrical support was changed to Ra 12.0 μm, Rz 73.0 μm, and Rmax 120.0 μm, in the same manner as in Example 1, the polyimide layer thickness 60 μm, A fixing seamless belt (total thickness: 73 μm) having a releasable resin layer thickness of 12 μm was obtained, but protrusions having a height of 15 μm and a diameter of 1 mm were generated. The inner surface of the belt had Ra of 1.2 μm, Rz of 7.3 μm and Rmax of 17.0 μm. Even when the obtained seamless belt was applied to the fixing device, the transportability was poor from the beginning, and white spots were generated in the fixed image at the protrusions.
[0049]
(Evaluation)
-Surface roughness (Ra, Rz, Rmax)-
In accordance with JIS B 0601, samples were taken from any five points on the inner surface of the belt, and with respect to the circumferential direction, a surface roughness meter (Surfcom 554A (manufactured by Tokyo Seimitsu Co., Ltd.)) with a cutoff of 0.32 mm and a measurement length of 2 Measurement was carried out at a driving speed of 0.12 mm / sec and a stylus load of 70 mg.
[0050]
The surface roughness of the metal cylindrical support was measured at a cutoff of 4 mm, a measurement length of 20 mm, a driving speed of 1.5 mm / sec, and a stylus load of 70 mg.
[0051]
-Toner fixing reduction rate-
The degree of decrease in chromaticity after rubbing with rubbing paper was expressed as a percentage with respect to the degree of melt coloring of the toner when 10 spots were printed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a main part of an image fixing apparatus using a belt fixing method.
DESCRIPTION OF SYMBOLS 1 Seamless belt 2 Pressing member 3 Heating drive roll 4 Nip part 5 Recording material 6 Sliding material

Claims (2)

A step of applying a polyimide precursor solution to a mold, curing it by heating and drying until it can be self-supported, and peeling the mold from the mold to obtain a polyimide precursor belt; A seamless belt comprising a step of inserting a support into the polyimide precursor belt, a step of heating the polyimide precursor belt together with the support to complete an imide conversion reaction, and a step of removing the seamless belt from the support. In the manufacturing method,
The surface roughness of the support is Rmax of 1.4 to 50.0 μm, Rz of 1.0 to 40.0 μm, and Ra of 0.1 to 5.0 μm,
The support has a thermal coefficient of thermal expansion greater than that of the polyimide precursor belt,
A method for producing a seamless belt, wherein when the polyimide precursor belt is heated together with the support, the support presses the polyimide precursor belt from the inside. A seamless belt obtained by the production method according to claim 1,
The seamless belt is pressed by a pressing member disposed on the inner side of the seamless belt against a heating drive roll disposed to face the outer side of the seamless belt to form a nip portion through which the recording material passes on the outer surface of the seamless belt. The sliding member is disposed on the sliding surface of the pressing member, and is used by running a lubricant between the sliding member and the inner surface of the seamless belt .
The seamless belt has an inner surface roughness Rmax of 0.18 to 8.00 μm, Rz of 0.10 to 3.50 μm, and Ra of 0.02 to 0.50 μm.

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