JP2002225051A - Seamless belt and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a uniform seamless belt which has a generally correct size and a good inner surface precision, and to provide a method for producing the belt. SOLUTION: The seamless belt is pressed to a heated driving roll arranged to face the outside of the belt by a press member arranged inside the belt, a nip for making a recording material pass is formed on the outer surface of the belt while a slide material is arranged on the slide surface of the press member, and the belt can travel with a lubricant arranged between the slide material and the inner surface of the belt. The inner surface of the belt has surface roughness Rmax of 0.18-8.00 μm, Rz of 0.10-3.50 μm, and Ra of 0.020-0.50 μm. In the method for producing the belt, a support which has an outside diameter smaller than the inside diameter of a polyimide precursor belt and has surface roughness Rmax of 1.4-50.0 μm, Rz of 1.0-40.0 μm, and Ra of 0.1-5.0 μm is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a seamless belt for an electrophotographic image forming apparatus and a method for manufacturing the same.
More specifically, the present invention relates to a fixing and conveying belt, a transfer and fixing belt used for an electrophotographic copying machine, a printer, a facsimile, and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, rolls and drums have been used as rotating members for electrophotographic image forming apparatuses.

[0003] In recent years, in order to solve the miniaturization of the device, etc.,
Plastic belts have been put to practical use in place of these members. As a belt used for such an application, a seamless belt made of a thermoplastic resin such as a polycarbonate or an ethylene tetrafluoroethylene copolymer is known (JP-A-10-10880, JP-A-2000-25097, etc.). ).

However, the thermoplastic resin has low heat resistance and durability, and is manufactured by a method such as die extrusion. The belt used was not satisfactory for practical use.

On the other hand, a seamless belt made of a thermosetting polyimide resin for an image forming apparatus has been proposed. As a method for producing these seamless belts, a method in which a polyimide precursor solution is applied to a core, a solvent is removed and an imide conversion reaction is performed, and the polyimide precursor solution is applied to the inner surface of a cylindrical mold to form a coating film After the formation, a method of intermittently performing the removal of the solvent and the imidization as it is, and a method in which the polyimide precursor solution is applied to the inner surface of the cylindrical mold to form a film, and then the solvent is partially used until the film itself can be supported After the removal and partial imidization, the mold is peeled off, the tubular mold is replaced, and the solvent is removed and the imidization reaction is completed.

[0006]

However, in these methods, when the solvent is completely removed and the imide conversion reaction is completed, the solvent or the ring-closing water of the polyimide precursor solution causes a gap between the belt and the mold supporting the belt. There is a problem that this causes the belt to bulge or become uneven. On the other hand, as means for solving this problem, it has been proposed to provide a large number of fine through holes around a tubular mold (Japanese Patent Application Laid-Open No. 10-258434). However, such fine through-holes cause variations in characteristics such as the inner surface and the film thickness of the seamless belt. In addition, since the tubular mold itself is held in a high-temperature furnace for a long time, the strength of the mold itself is insufficient compared to a tubular mold having no through hole, and the mold is bent. This not only causes dimensional defects such as occurrence of whirl, but also causes a decrease in accuracy of the inner peripheral surface of the seamless belt.

On the other hand, such a seamless belt has a pressing member disposed on the inner side thereof to press the seamless belt against a heating drive roll disposed on the outer side of the belt so as to allow the recording material to pass through the outer surface of the belt. A nip portion is formed, and a sliding material is arranged on a sliding surface of the pressing member, and a lubricant is interposed between the sliding member and an inner surface of the belt, so that the belt can be used for a fixing device. Have been. Since this fixing device is driven while being pressed by a heating drive roll disposed 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. The agent is interposed. However, when the surface accuracy of the inner peripheral surface of the seamless belt is low, the supply of the lubricant from the lubricant supply means is not stable, and the transportability of the belt becomes unstable.

Accordingly, an object of the present invention is to provide a seamless belt with less dimensional defects, good surface accuracy on the inner peripheral surface and no unevenness, and a method for manufacturing the same.

[0009]

The above objects 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 a recording material to pass through the outer surface of the seamless belt by pressing against a heating drive roll disposed opposite to the outside with a pressing member disposed inside the seamless belt. A seamless belt that can run with a lubricant interposed between the sliding member and the inner surface of the seamless belt, with the sliding member disposed on the sliding surface of the pressing member, and a surface of the inner surface thereof. As for the roughness, Rmax is 0.18-
8.00 μm and Rz 0.10 to 3.50 μm and R
a is 0.02 to 0.50 μm.

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.

In FIG. 1, a pressing member 2 is disposed inside a 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 nip portion 4 is formed outside the seamless belt 1 by pressing the seamless belt 1 against the heating drive roll 3 by the pressing member 2. The nip portion 4 is a portion through which the recording material 5 passes by the seamless belt 1 traveling along with the rotation of the heating drive roll 3. The image is fixed on the recording material 5 to which the heat-sensitive ink 51 is temporarily attached by heating and pressing during the passage. In order for the seamless belt 1 to run stably, it is necessary to lower the friction coefficient of the inner surface of the belt. For this purpose, a sliding member 6 is arranged 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.

Here, the sliding material is a seamless belt 1
Refers to a material that reduces the coefficient of friction with the inner surface of
Examples thereof include a fluororesin sheet and the like, and a glass fiber sheet and the like coated with a fluororesin.

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, device, or the like.

In order to stably supply the lubricant and maintain good transportability of the seamless belt, the surface roughness (Ra) of the inner surface of the seamless belt is 0.02 to 0.5 μm, preferably 0 to 0.5 μm. 0.03 to 0.4 μm, more preferably 0.04 to 0.2 μm. The belt has a surface roughness (Rz) of 0.1 to 3.5 μm,
Preferably it is 0.2 to 3.0 μm. The surface roughness (Rmax) of the belt is 0.18 to 8.00 μm.
And preferably 0.2 to 7.00 μm.

The surface roughness (Ra, Rz and Rmax)
Is a value defined by JIS B 0601 and measured by the method described in Examples.

The method for producing a seamless belt according to the present invention comprises:
This is a method suitably used for producing the seamless belt of the present invention. That is, the manufacturing method is a step of applying a polyimide precursor solution to a mold, curing by heating and drying until it can be self-supported, and peeling the mold from the mold to obtain a polyimide precursor belt, from the inner diameter of the polyimide precursor belt. Inserting the support having a smaller outer diameter into the polyimide precursor belt, 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 support has a surface roughness of Rmax of 1.4 to 50.0 μm and Rz of 1.0 to 40.0 μm.
And Ra is 0.1 to 5.0 μm.

The surface roughness (Ra) of the support is such that the 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 is the surface property of the inner or outer surface of the seamless belt. 0.1 ~
It is 5.0 μm, preferably 0.3 to 4.0 μm, more preferably 0.5 to 3.0 μm. Similarly, the surface roughness (Rz) of the support is 1.0 to 40.
0 μm, and preferably 2.0 to 35.0 μm. Similarly, the surface roughness of the support (Rmax)
Is from 1.4 to 50.0 μm, preferably from 3.0 to 50.0 μm.
45.0 μm.

The surface roughness (Ra, Rz and Rmax)
Is a value defined by JIS B 0601 and measured by the method described in Examples.

In the production method of the present invention, the support preferably has a coefficient of linear thermal expansion larger than that of the polyimide precursor belt. In this case, since the heat is set while the support presses the seamless belt from the inside at the time of heating, a seamless belt having better dimensional accuracy and surface characteristics can be obtained. Conversely, if the coefficient of linear thermal expansion is small, the gap between the support and the polyimide precursor belt expands during heating, and the remaining solvent and ring-closing water evaporate efficiently from the inner surface of the belt. Can not.

The coefficient of linear thermal expansion of the polyimide resin varies depending on the amount of the residual solvent and the composition of the polyimide constituting the belt, but is generally from 1 × 10 ^{−5 to} 3 × 10 ⁻⁵ cm / cm / ° C. Therefore, the coefficient of linear thermal expansion of the support is usually preferably larger than the coefficient of linear thermal expansion of the polyimide resin, more preferably 2 × 10 ⁻⁵ cm / cm / ° C. or more,
It is even more preferably at least 3 × 10 ⁻⁵ cm / cm / ° C.

The coefficient of linear thermal expansion is a value measured according to JIS K 7197.

Materials for the support satisfying the above requirements include:
Examples include metals such as copper, aluminum, magnesium, zinc, and manganese, and alloys thereof, as well as glass and ceramic.

[Operation and Effect] The seamless belt of the present invention has few dimensional defects, has good surface accuracy on the inner peripheral surface, has no unevenness, and is suitable as a seamless belt such as a fixing belt and a transfer fixing belt in an image forming apparatus. Can be used. Further, according to the production method of the present invention, such a seamless belt can be efficiently produced.

[0024]

Embodiments of the present invention will be described in detail below.

The seamless belt of the present invention comprises a step of applying a polyimide precursor solution to a mold, curing by heating and drying until self-supporting, and peeling the polyimide precursor from the mold to obtain a polyimide precursor belt. A step of inserting a support having an outer diameter smaller than the inner diameter of the belt into the inside of the polyimide precursor belt, a step of heating the polyimide precursor belt together with the support to complete the imide conversion reaction, and It is manufactured by a method including a step of taking out a seamless belt.

The polyimide precursor solution used in the present invention comprises:
It is obtained by reacting an acid dianhydride component and a diamine component in a solvent. As the acid dianhydride component, 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, 1,4,5
8-naphthalenetetracarboxylic dianhydride and the like.

On the other hand, as the diamine component, 4,4′-
Diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane,
3,3′-dichlorobenzidine, 4,4′-diaminodiphenylsulfide, 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.

As a solvent for the polymerization reaction of these acid dianhydrides and diamines, any suitable solvent can be used. From the viewpoint of solubility and the like, organic polar solvents are preferably used.
-Dialkylamides are preferred. Specifically, N, N-
Dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine Dimethylsulfoxide, tetramethylenesulfone, dimethyltetramethylenesulfone, etc., and these can be used alone or in combination.

By subjecting the acid dianhydride component and the diamine component to a polymerization reaction in an organic polar solvent, a polyimide precursor solution is obtained. 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. Further, the reaction temperature is preferably set to 80 ° C. or less,
The reaction time is preferably 0.5 to 10 hours.

Since the solution viscosity increases as the polymerization reaction proceeds, the viscosity can be adjusted. Further, the viscosity can be adjusted by the monomer concentration. Specifically, the viscosity is preferably from 10 to 10,000 poise, and from 50 to 80 poise.
More preferably, it is 00 poise.

The polyimide precursor solution of the present invention may contain a filler depending on various purposes such as thermal conductivity, conductivity, antistatic property, semi-conductivity, high slidability, high strength, and high elasticity, and its use. May be added. For example, heat conductive inorganic powders such as aluminum nitride, boron nitride, alumina, silicon carbide, silicon carbide, silica, and the like, and conductive or semiconductive powders such as carbon black, aluminum, nickel, tin oxide, and potassium titanate; Polytetrafluoroethylene (P
TFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PF
A) the fluororesin and the like. Filling amount of filler
It can be determined according to the purpose within the scope of the present invention.

The polyimide precursor solution is applied to a mold. The mold to be used may be any mold as long as it has been conventionally used for the production of a seamless belt. Usually, a cylindrical mold according to the shape of the belt is used, and the inner surface is coated. Known methods can be applied to the method of uniformly applying the solution to the cylindrical mold, and examples thereof include a method of centrifugal molding, a method of applying with a dispenser, a method of using a scraper, and a method of using a bullet-shaped traveling body. Can be Examples of the material of the mold include various materials such as metal, glass, and ceramic from the viewpoint of heat resistance.

The polyimide precursor solution uniformly coated on the cylindrical mold in this manner is cured by heating and drying until it can be self-supported, and then the polyimide precursor belt is peeled off from the mold to obtain a polyimide precursor solution. . The heating temperature is not particularly limited as long as the applied solvent can be evaporated, and can be appropriately set. The temperature is preferably 230 ° C. or lower in order to prevent generation of microvoids due to rapid evaporation of the solvent in the polyimide precursor solution, and is 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.

As a method of peeling the polyimide precursor belt from the cylindrical mold, for example, a method of forcing air into a minute through-hole provided in advance on a peripheral wall of an end of the mold and the like can be mentioned. It is preferable that the peripheral surface of the cylindrical mold is previously subjected to a release treatment using a silicone resin or the like, since the workability of separating the polyimide precursor belt is improved.

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. The residual solvent is removed, the ring-closing water is removed, and the imide conversion reaction is completed.

The heating temperature at this time is preferably equal to or higher than the heating temperature on the cylindrical mold from the viewpoint of removing the residual solvent and ring-closing water, and is referred to as the heat resistance and the coefficient of linear thermal expansion of the polyimide precursor belt and the support. From the viewpoint, 400 ° C. or lower is preferable. Usually, the heating time at this time is 10 to 60 minutes.

It is needless to say that at this time, it is necessary to appropriately set the dimensions of the support so that the support has a preferable inner diameter and outer diameter difference as a seamless belt according to the purpose.

The belt thus obtained is taken out of the support. Normally, the support may be left to cool at room temperature and then removed after the support thermally shrinks.

Further, 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, In order to provide further functions such as photoconductivity, a fluororesin such as PTFE, FEP, and PFA, a silicone rubber or a fluororubber, etc. may be further laminated on the outer peripheral surface of the belt using a method such as spray coating and dipping. I do not care. When used as a heating belt of the electromagnetic induction heating type, nickel, iron, cobalt,
An electromagnetic induction heating layer made of copper, aluminum, an alloy thereof, or the like may be provided by using a method such as plating or ion plating.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and the like specifically showing the configuration and effects of the present invention will be described below.

Example 1 147 g of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 54 g of p-phenylenediamine were dissolved in 732 g of N-methyl-2-pyrrolidone (solid content: 20%). % By weight) and reacted with stirring at room temperature in a nitrogen atmosphere to obtain a 3,000 poise polyimide precursor solution. After applying the polyimide precursor solution 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 degassing is performed to remove bubbles in the coating film to obtain a uniform coating surface. Was. Next, the mold was heated from room temperature to 180 ° C. for 30 minutes and cured (partially removing the solvent and partially converting into imide) until it could be held as a belt itself to obtain a polyimide precursor belt.
After the belt was released from the mold, the surface roughness Ra was 2.5 μm, Rz was 20.0 μm, and Rmax was 27.
0 μm, coefficient of thermal expansion 2.6 × 10 ⁻⁵ cm / cm / ° C.
Is replaced with a metal cylindrical support, which is
The temperature was raised to 370 ° C. at a rate of temperature increase of 370 ° C./min to remove the residual solvent and ring-closed water, complete the imide conversion reaction, and then cooled to obtain a 60 μm-thick polyimide seamless belt. After performing a primer treatment on the outer surface of the seamless belt on the metallic support, PF is used as a release resin.
The aqueous dispersion of A was spray-coated, then heated to 370 ° C. while being inserted into the support, and then cooled to obtain a seamless belt having a release resin layer of 10 μm (total thickness: 71 μm).

The surface roughness of the inner surface of this belt was Ra 0.2 μm, Rz 2.3 μm and Rmax 3.7 μm.
m, and no swelling or poor appearance due to solvent swelling was observed. When this belt was tested by using an actual fixing device, the conveyance of the belt was good, and a good fixed image was obtained (fixation reduction rate of toner was 4%).

Example 2 In Example 1, the surface roughness of the metal cylindrical support was 3.0 μm for Ra and 30 μm for Rz.
A fixing seamless belt having a polyimide layer thickness of 60 μm and a release resin layer thickness of 10 μm (total thickness of 71 μm) in the same manner as in Example 1 except that 0 μm and Rmax were set to 40.0 μm.
μm).

The surface roughness of the inner surface of this belt was Ra 0.3 μm, Rz 3.0 μm, and Rmax 6.0 μm.
m, and no swelling or poor appearance due to solvent swelling was observed. When this belt was tested by using an actual fixing device, the conveyance of the belt was good, and a good fixed image was obtained (fixation reduction rate of the toner was 7%).

Comparative Example 1 The metal cylindrical support of Example 1 had a surface roughness Ra of 7.0 μm and Rz of 42.
A fixing seamless belt having a polyimide layer thickness of 60 μm and a release resin layer thickness of 12 μm (total thickness of 73 μm) in the same manner as in Example 1 except that 0 μm and Rmax were set to 60.0 μm.
μm).

The surface roughness of the inner surface of this belt was Ra 0.6 μm, Rz 4.0 μm, and Rmax 9.0 μm.
However, when this belt was run on an actual fixing device, the fixed image was unclear due to poor fixability (a reduction rate of toner fixation of 45%).

[Comparative Example 2] In Example 1, the surface roughness of the metal cylindrical support was Ra of 0.05 μm and Rz of 0.5.
A fixing seamless belt having a polyimide layer thickness of 60 μm and a release resin layer thickness of 12 μm (total thickness of 7 μm) in the same manner as in Example 1 except that 80 μm and Rmax were set to 1.00 μm.
3 μm), but swelling occurred due to a solvent or the like trapped 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 has an Ra of 0.01 μm, an Rz of 0.07 μm, and an Rmax of 0.2 μm.
It was 15 μm. Even when the obtained seamless belt was applied to a fixing device, the transportability was poorer than the initial stage, and it was not practical.

Comparative Example 3 In Example 1, the surface roughness of the metal cylindrical support was Ra of 12.0 μm and Rz of 7
Except that 3.0 μm and Rmax were 120.0 μm, the polyimide layer thickness was 60 μm in the same manner as in Example 1.
A fixing belt having a release resin layer thickness of 12 μm (total thickness: 73 μm) was obtained. The height was 15 μm and the diameter was 1 mm.
Projections occurred. The inner surface of the belt has Ra of 1.2.
μm, Rz was 7.3 μm, and Rmax was 17.0 μm. Even when the obtained seamless belt was applied to a fixing device, the transportability was poorer than the initial stage, and white spots occurred in the fixed image at the projections.

(Evaluation) Surface Roughness (Ra, Rz, Rmax) According to JIS B0601, samples are taken from any five points on the inner surface of the belt, and a surface roughness meter (Surfcom 554A ( Cutoff 0.32 mm, measurement length 2.5 mm, drive speed 0.
The measurement was performed at 12 mm / sec and a stylus load of 70 mg.

The surface roughness of the metal cylindrical support was as follows: cut-off 4 mm, measurement length 20 mm, drive speed 1.5 mm /
The measurement was performed with a stylus load of 70 mg for sec.

-Reduction rate of toner fixation-The degree of decrease in chromaticity after rubbing with a piece of rubbing paper was shown as a percentage of the degree of coloration of the toner when ten spots were printed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part of an image fixing device using a belt fixing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Seamless belt 2 Pressing member 3 Heating drive roll 4 Nip part 5 Recording material 6 Sliding material

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29K 79:00 B29K 79:00 B29L 29:00 B29L 29:00 F term (Reference) 2H033 BA11 BA12 BE09 2H200 GB22 GB23 GB25 GB26 GB40 JA07 JA08 JA25 JB32 MA02 MC06 4F205 AA40 AG16 GA06 GB01 GC04 GN29 GW06 GW31 4F213 AA40 AB01 AD18 AE08 AE09 AG16 AH33 WA03 WA53 WA58 WA83 WB01 WC01 4J043 PA02 QA31 UA13 SA06 UA31 XA31 TA06

Claims (3)

[Claims] Claims: 1. A polyimide precursor solution is applied to a mold,
Curing until it can be self-supported by heating and drying, peeling from the mold to obtain a polyimide precursor belt, inserting a support having an outer diameter smaller than the inner diameter of the polyimide precursor belt into the inside of the polyimide precursor belt Performing the imide conversion reaction by heating the polyimide precursor belt together with the support, and removing the seamless belt from the support, wherein the surface roughness of the support is Is
Rmax is 1.4 to 50.0 μm and Rz is 1.0 to 4
A method for producing a seamless belt, wherein 0.0 μm and Ra are 0.1 to 5.0 μm. 2. The method according to claim 1, wherein the coefficient of linear thermal expansion of the support is larger than the coefficient of linear thermal expansion of the polyimide precursor belt. 3. A nip that presses a seamless belt with a pressing member disposed inside the seamless belt against a heating drive roll disposed opposite to the outside of the seamless belt to pass a recording material through the outer surface of the seamless belt. Forming a portion, and arranging a sliding member on a sliding surface of the pressing member, and running with a lubricant interposed between the sliding member and an inner surface of the seamless belt. The surface roughness of the inner surface of the seamless belt is such that Rmax is 0.18 to 8.00 μm and Rz is 0.1 to 0.8 μm.
10 to 3.50 μm and Ra 0.02 to 0.50 μm
Is a seamless belt.