JP3428579B2 - Seamless belt - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seamless belt, and more particularly to a resin seamless belt used in a fixing device such as a printer or a copying machine.

[0002]

2. Description of the Related Art As a seamless belt made of resin used in a fixing device such as a printer or a copying machine, a Young's modulus of a cured film is obtained by centrifugal molding using a dispersion liquid in which fine powder is dispersed in a thermosetting resin solution. A seamless belt of 350 kg / mm ² (Japanese Unexamined Patent Publication No. 61-202811), which contains a thermosetting polyimide resin as a main component and has fluorine resin fine particles dispersed and unevenly distributed on the surface thereof, and also contains a heat conductive powder. Seamless tubular film (JP-A-11-156971)
No. gazette) is known. Also, as a polyimide film having a metal plating layer, for polyimide-based polymers
A polyimide film containing 0.01 to 100% by weight of metal powder is known (JP-A-7-216225).

[0003]

However, as the size and weight of printers, copiers, etc. are made smaller and the fixing speed is made faster, the heat resistance and thermal conductivity are more excellent, especially at high temperature. There has been a demand for a seamless belt with little change in mechanical properties with, but a conventional seamless belt containing a polyimide resin as a main component has a large decrease in properties under high temperature, and does not satisfy the above required properties. There's a problem.

Further, when the seamless belt is formed into a film by the centrifugal casting method, there is a problem that the seamless belt is difficult to peel off from the manufacturing apparatus. In particular, when molding is performed from a resin solution in which fine metal powder is mixed with a polyimide resin solution, peeling is difficult even if a release agent is used, and there is a problem that productivity is reduced.

The present invention has been made in order to solve such a problem, and provides a seamless belt which has little deterioration in mechanical properties at room temperature and in the vicinity of use temperature and which is excellent in productivity by a centrifugal casting method. The purpose is to do.

[0006]

The seamless belt of the present invention is a seamless belt made of a resin film, wherein the resin film is a mixed resin film of an aromatic polyimide resin and an aromatic polybenzimidazole resin. A film is obtained by forming a mixed resin solution of at least an aromatic polyamic acid resin solution and an aromatic polybenzimidazole resin solution by a centrifugal casting method,
The tensile strength of the mixed resin film at 200 ° C is 2
It is characterized by having 80% or more of the tensile strength at 5 ° C.

The seamless belt is characterized in that fine metal powder is dispersed and mixed in the outer peripheral surface layer thereof.
Here, the outer peripheral surface layer refers to the vicinity of the surface side of the outer periphery of the seamless belt in which a heating device or the like is installed, when the seamless belt is viewed in the thickness direction cross section. Further, the seamless belt is characterized by having a plating layer on the outer peripheral surface thereof.

[0008]

Aromatic polyimide resins, especially poly (4,
The 4'-oxydiphenylenepyromellitimide) resin shows a decrease in mechanical properties from around 200 ° C. Further, since an aromatic polyimide resin is generally formed into a film through a dehydration / ring-closing reaction of a polyamic acid, it is difficult to blend it with other resins. In the present invention, when an aromatic polyimide resin is blended with an aromatic polybenzimidazole resin, they can be easily blended with each other, and deterioration of mechanical properties at high temperatures can be suppressed. Further, even if the fine metal powder is blended, the mixed solution facilitates the peeling of the seamless belt formed into a film from the centrifugal casting method manufacturing apparatus. As a cause of easy peeling, the concentration of the carboxyl group present in the polyamic acid is relatively low, or due to the interaction with the benzimidazole ring, the adhesive force with the cylindrical mold that is the manufacturing apparatus during film formation is It is considered weakened. The present invention has been made based on such findings.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A seamless belt of the present invention is shown in FIG.
2 will be described. 1 and 2 are partially enlarged cross-sectional views in the thickness direction of the seamless belt. The seamless belt 1 is formed of a resin film 2, and the resin film 2 is a mixed resin film of an aromatic polyimide resin and an aromatic polybenzimidazole resin. Further, the fine metal powder 3 is applied to the outer peripheral surface 2a of the outer peripheral surface layer of the mixed resin film 2.
It is dispersed and compounded in such a manner that the concentration increases as it gets closer to. As shown in FIG. 2, the seamless belt 1 can further be provided with a metal plating layer 4 on the outer peripheral surface 2a.

The aromatic polyimide resin constituting the mixed resin film is a resin having the repeating unit shown in Chemical formula ₁ , R ₁ is a residue of an aromatic tetracarboxylic acid or its derivative, and R ₂ is an aromatic diamine. Alternatively, it is a residue of its derivative. Examples of such R ₁ or R ₂ include a phenyl group, a naphthyl group, a diphenyl group, and an aromatic group in which these are linked by a linking group such as a methylene group, an ether group, a carbonyl group and a sulfone group. R ₁ and R ₂ may be the same or different.

[0012]

[Chemical 1]

Examples of the aromatic tetracarboxylic acid or its derivative include pyromellitic dianhydride, 2,2 ',
3,3′-biphenyltetracarboxylic acid dianhydride, 3,
3 ', 4,4'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, Examples thereof include bis (2,3-dicarboxyphenyl) methanoic acid dianhydride, which may be used alone or in combination. Examples of the aromatic diamine or its derivative include 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 4,4 '.
Examples include diamines or diisocyanates such as ′ -diaminodiphenylmethane, metaphenylenediamine and paraphenylenediamine.

When the seamless belt of the present invention is manufactured by the centrifugal casting method, it is prepared in the form of a varnish which is an aromatic polyimide resin solution. Examples of the varnish include polyamic acid varnish obtained by reacting the above-mentioned aromatic acid dianhydride and aromatic diamine in an aprotic polar solvent. Polyamic acid varnish is prepared by dissolving an aromatic diamine in a solvent containing an aprotic polar solvent such as dimethylacetamide, dimethylformamide, N-methylpyrrolidone as a main component, and cooling the reaction system to suppress a temperature rise due to heat of reaction. However, it can be obtained by adding an equivalent amount of aromatic dianhydride in the form of powder at a temperature of approximately room temperature or lower and performing an addition reaction. By forming a film from this polyamic acid varnish and then heating it or immersing it in a mixed solvent of acetic anhydride and pyridine, a ring closure reaction occurs and an aromatic polyimide resin film is obtained. The process is shown in Chemical formula 2.

[0015]

[Chemical 2]

The reason for going through the above process is that the aromatic polyimide resin does not dissolve in a general solvent except concentrated sulfuric acid and the like. Therefore, in the state of the polyamic acid varnish, there is a carboxyl group which is not ring-closed, and it becomes easy to form a complex with a metal ion or the like. The present invention, at the time of film formation, by mixing an aromatic polyamic acid resin varnish and an aromatic polybenzimidazole resin varnish, the carboxyl group concentration is relatively decreased, even if metal fine powder is blended. It is thought that it can be easily peeled from the centrifugal casting device.

The aromatic polybenzimidazole resin is a resin having a repeating unit represented by Chemical formula ₃ , and R ₃ is a residue of an aromatic tetraamine or a derivative thereof having two pairs of amino groups in the ortho positions on the aromatic ring. Group, R
₄ is a residue of an aromatic dicarboxylic acid or its derivative. Examples of such a residue include a phenyl group, a naphthyl group, a diphenyl group, and an aromatic group in which these are linked by a linking group such as a methylene group, an ether group, a carbonyl group, and a sulfone group.

[0018]

[Chemical 3]

Aromatic polybenz by dissolving a resin obtained by polycondensing an aromatic tetraamine and an aromatic dicarboxylic acid in one step and / or two steps in a solvent containing an aprotic polar solvent as a main component. A varnish that is an imidazole resin solution is obtained.

Various methods can be adopted as a method for mixing the aromatic polyamic acid resin solution and the aromatic polybenzimidazole resin solution. For example, both solutions are directly mixed.
A powdered aromatic polybenzimidazole resin is dissolved in an aromatic polyamic acid resin solution. Alternatively, an aromatic diamine is dissolved in an aromatic polybenzimidazole resin solution and an equivalent amount of aromatic dianhydride is added as powder while cooling the reaction system. Of these methods, the method of directly mixing both solutions is a simple method and is a preferable method.

The mixing ratio of the aromatic polyamic acid resin solution and the aromatic polybenzimidazole resin solution is such that when the mixed resin film is formed, the resin film has a temperature of 200 ° C.
The tensile strength at
It should be within the range that can be maintained at%. Specifically, the aromatic polybenzimidazole resin is blended in a solid resin ratio of 10% by weight or more, preferably 20% by weight or more based on the entire mixed resin film after film formation. The upper limit of the compounding amount of the aromatic polybenzimidazole resin is preferably 50% by weight. If the amount of the aromatic polybenzimidazole resin is less than 10% by weight, the tensile strength at 200 ° C cannot maintain 80% or more of the tensile strength at 25 ° C. On the other hand, if it exceeds 50% by weight, dimensional change due to moisture absorption and cost increase will occur.

In the present invention, fine metal powder can be added to the above resin solution. By mixing the metal fine powder and forming a film by the centrifugal casting method, the fine metal powder is dispersed in the outer peripheral surface layer by inclining so that the concentration of the metal fine powder becomes higher as it approaches the outer peripheral surface of the seamless belt. Fixed. Examples of the fine metal powder that can be used include fine metal powders of gold, silver, copper, palladium, nickel, aluminum and the like. In order to perform the electroless plating treatment described later, copper, palladium,
Nickel fine powder is preferred. The particle size of the fine metal powder is 0.01 to 80 μm, preferably 1 to 50 μm. 0.
If it is less than 01 μm, the concentration gradient of the fine metal powder will not be sufficient, and if it exceeds 80 μm, the surface smoothness of the seamless belt will be poor. The compounding ratio of the fine metal powder is 1 to 80% by weight, preferably 10 to 50% by weight, based on the whole mixed resin containing the fine metal powder. If it is less than 1% by weight, electroless plating cannot be performed without pretreatment.
On the other hand, when it exceeds 80% by weight, the surface smoothness of the seamless belt is poor and the mechanical strength is extremely lowered.

A metal plating layer can be provided on the outer peripheral surface of the seamless belt. By providing the metal plating layer, the thermal conductivity can be improved, or the potential of the seamless belt can be set to the ground potential. The mixed resin film provided with the metal plating layer may be either the mixed resin film alone or a mixed resin film in which fine metal powder is dispersed and mixed in the outer peripheral surface layer. In the case of a mixed resin film alone, electroless plating is performed after performing a predetermined pretreatment or activation treatment. In the case of a mixed resin film in which fine metal powder is dispersed and mixed, electroless plating is performed directly or after performing a predetermined pretreatment or activation treatment. Note that direct electroplating can be performed depending on the mixing ratio of the fine metal powder. By using the mixed resin film in which the fine metal powder is dispersed and blended, a plating layer having excellent adhesive strength with the resin film can be obtained, and thus it is suitable for the present invention.

Electroless plating is carried out using sodium hypophosphite,
A known method in which the resin film is immersed in an electroless plating solution containing at least a reducing agent such as sodium hyposulfite and a metal ion such as copper ion or nickel ion and heated to metal-plat the surface can be adopted. The electroless plating solution contains a complexing agent such as a tartrate salt, a citrate salt, a Rochelle salt, ethylenediaminetetraacetic acid disodium salt and sodium acetate, and a pH buffering agent. Also, electroplating can be performed after electroless plating.

The seamless belt of the present invention is obtained by forming a film of a mixed resin solution of at least an aromatic polyamic acid resin solution and an aromatic polybenzimidazole resin solution by a centrifugal casting method. The centrifugal casting method involves injecting a mixed resin solution into a rotating drum having a predetermined width and inner diameter, and heating the rotating drum while reducing the pressure while rotating the rotating drum at a predetermined number of revolutions. It is a method of forming a seamless resin film. The solvent evaporated from the mixed resin solution is discharged to the outside of the rotary drum by the airflow flowing into the rotary drum. The seamless resin film may be further cured by heating after being taken out from the rotating drum.

Optimum conditions for film formation by centrifugal casting are set depending on the size of the rotating cylinder, the thickness of the seamless belt, the characteristics of the mixed resin solution such as the type and viscosity of the solvent, and the type and blending amount of the fine metal powder. To be done. For example, inner diameter φ30mm, length
When using a 360 mm rotating cylinder, the viscosity of the mixed resin solution is
1 to 4 Pa ・ s, decompression degree is -400 to -750 mmHg, rotation speed is 3000 to
7500 rpm, the air flow rate is 0.1 to 1 liter / min, and the drum temperature is preferably 70 to 120 ° C. Further, the heating condition after taking out from the rotary drum is preferably about 350 ° C. for about 30 minutes. By the above conditions, a seamless film formed from a mixed resin solution of an aromatic polyamic acid resin solution and an aromatic polybenzimidazole resin solution can be easily taken out without adhering to the inner surface of the rotating drum, and at a high temperature. In, the deterioration of mechanical properties is reduced. In addition, the viscosity of the mixed resin solution for efficiently inclining and dispersing the fine metal powder in the thickness direction of the seamless belt is preferably 2 to 3 Pa · s.

[0027]

Example 1 Aromatic polyimide varnish (manufactured by Ube Industries, Ltd., solid content concentration as polyamic acid: 18% by weight) Solution 17.8 g
And an aromatic polybenzimidazole varnish (manufactured by Clariant Japan KK, solid content concentration: 10% by weight) solution 8.
After mixing with O g, the mixture was diluted with 14.2 g of dimethylacetamide to obtain a mixed resin solution. The viscosity of the obtained mixed resin solution is 3 Pa · s, and the weight ratio of the aromatic polyimide resin and the aromatic polybenzimidazole resin is 8: 2. The obtained solution is poured into a cylindrical mold (φ30mm x 360mm), the degree of vacuum is -560mmHg, the rotation speed is 4000rpm, and the air flow rate is 0.5.
The film was obtained by spinning at liter / min at ambient temperature of 90 ° C. This film was placed in an oven heated to 370 ° C., left for 20 minutes and then taken out to obtain a seamless belt made of a mixed resin film and having a thickness of 80 μm. A test piece is prepared from this seamless belt, and ASTM D882 is used.
The tensile strength at 25 ° C and 200 ° C was measured according to -64T. The results are shown in Table 1.

Example 2 13.3 g of aromatic polyimide varnish (manufactured by Ube Industries, Ltd., solid content concentration as polyamic acid: 18% by weight)
And an aromatic polybenzimidazole varnish (Clariant Japan KK, solid content concentration: 10% by weight) solution 1
After mixing with 6.0 g, it was diluted with 10.7 g of dimethylacetamide to obtain a mixed resin solution. The viscosity of the obtained mixed resin solution is 2 Pa · s, and the weight ratio of the aromatic polyimide resin and the aromatic polybenzimidazole resin is 6: 4. An 80 μm-thick seamless belt made of a mixed resin film was obtained by the same centrifugal molding method as in Example 1, and the tensile strength was measured under the same conditions as in Example 1. The results are shown in Table 1.

Comparative Example 1 40.0 g of aromatic polybenzimidazole varnish (Clariant Japan KK, solid content concentration: 10% by weight) solution
Is injected into a cylindrical mold (φ30mm x 360mm) and the decompression degree is -560m.
A film was obtained by rotation at mHg, a rotation speed of 4000 rpm, an air flow rate of 0.5 l / min, and an ambient temperature of 90 ° C. This film was placed in an oven heated to 350 ° C., left for 15 minutes and then taken out to obtain a seamless belt having a thickness of 80 μm. The tensile strength was measured under the same conditions as in Example 1. The results are shown in Table 1.

Comparative Example 2 22.2 g of an aromatic polyimide varnish (manufactured by Ube Industries, Ltd., solid content concentration as polyamic acid: 18% by weight) was diluted with 17.8 g of dimethylacetamide to prepare a polyimide solution. This solution is poured into a cylindrical mold (φ30mm x 360mm), the degree of vacuum is -560mmHg, the rotation speed is 4000rpm, and the air flow rate is
A film was obtained by spinning at 0.5 l / min, ambient temperature 90 ° C. Place this film in an oven heated to 200 ° C
Let it sit for 15 minutes and gradually raise the temperature to 370 ° C at the end 2
After leaving it for 0 minutes, it was taken out to obtain a seamless belt having a thickness of 80 μm. The tensile strength was measured under the same conditions as in Example 1. The results are shown in Table 1.

[0031]

[Table 1]

As shown in Table 1, the seamless belts obtained in Examples 1 and 2 have a tensile strength at 200 ° C. of 80% or more of the tensile strength at 25 ° C., and their mechanical properties at high temperature. Was excellent. On the other hand, Comparative Example 2 showed a large decrease in tensile strength at 200 ° C.
The seamless belt obtained in Comparative Example 1 had a larger dimensional change due to water absorption and a higher resin material cost than the seamless belts obtained in Examples 1 and 2.

Example 3 A mixed resin solution was prepared in the same blending ratio as in Example 1.
Into this mixed resin solution, fine copper powder (F
After adding 0.4 g of CC-2000 and Fukuda Metal Co., Ltd. and stirring with a stirrer for 30 minutes, the rotation speed of the cylindrical mold was 6000.
Under the same conditions as in Example 1 except that the rpm was set, a seamless belt in which fine copper powder was gradiently dispersed and mixed in the outer peripheral surface layer was obtained. The seamless belt thus obtained could be easily taken out from the inner surface of the cylindrical mold. Further, when the outer peripheral surface of the seamless belt was plated with copper by immersing it in an electroless copper plating solution, a copper plating film was easily formed.

Example 4 Copper fine powder was applied to the outer peripheral surface layer under the same conditions as in Example 3 except that 1.2 g of copper fine powder (FCC-2000, manufactured by Fukuda Metal Co., Ltd.) having an average particle size of 50 μm was added. To obtain a seamless belt in which gradient dispersion was blended. The seamless belt thus obtained could be easily taken out from the inner surface of the cylindrical mold. Further, when the outer peripheral surface of the seamless belt was plated with copper by immersing it in an electroless copper plating solution, a copper plating film was easily formed.

Comparative Example 3 An average particle size of 2 was added to the polyimide resin solution prepared in Comparative Example 2.
0 μm fine copper powder (FCC-2000, Fukuda Metal Co., Ltd.)
0.4g), stir for 30 minutes with a stirrer, inject this solution into a cylindrical mold (φ30mm × 360mm), and reduce the pressure.
560 mmHg, rotation speed 6000 rpm, air flow rate 0.5 l / min,
A film was obtained by spinning at an ambient temperature of 90 ° C. This film was placed in an oven heated to 200 ° C. for 15 minutes, the temperature was raised stepwise and left at 370 ° C. for 20 minutes at the end, and then taken out to obtain a seamless belt. The obtained seamless belt had excellent adhesion to the cylindrical mold and could not be peeled from the inner surface of the mold.

[0036]

The present invention comprises a mixed resin film of an aromatic polyimide resin and an aromatic polybenzimidazole resin, and the tensile strength at 200 ° C. is 80% or more of the tensile strength at 25 ° C. It is possible to obtain a seamless belt with little change in mechanical properties from room temperature even at high temperatures. Further, the seamless belt is easily peeled off from the manufacturing apparatus, and the productivity by the centrifugal casting method is excellent. Further, since the fine metal powder is dispersed and mixed in the outer peripheral surface layer of the seamless belt, the plating property is improved. As a result, it becomes easy to form a plating layer on the outer peripheral surface, and thus the thermal conductivity is excellent.

Since the mixed resin film forming the seamless belt is obtained by forming a mixed resin solution of at least an aromatic polyamic acid resin solution and an aromatic polybenzimidazole resin solution by a centrifugal casting method, the mixed resin film has high heat resistance. Excellent, seamless belts that are compatible with smaller and lighter printers and copiers and faster fixing speeds can be obtained.

[Brief description of drawings]

FIG. 1 is a partially enlarged sectional view of a seamless belt in a thickness direction.

FIG. 2 is a partially enlarged sectional view in the thickness direction of a seamless belt having a metal plating layer.

[Explanation of symbols]

1 seamless belt 2 resin film 3 fine metal powder 4 metal plating layer

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 15/20 101 B29D 29/00

Claims (3)

(57) [Claims] 1. A seamless belt comprising a resin film, wherein the resin film is a mixed resin film of an aromatic polyimide resin and an aromatic polybenzimidazole resin, and the mixed resin film contains at least an aromatic polyamic acid resin solution and an aromatic resin. It is obtained by forming a mixed resin solution with a group polybenzimidazole resin solution by a centrifugal casting method, and the tensile strength at 200 ° C. of the mixed resin film is 80% or more of the tensile strength at 25 ° C. A characteristic seamless belt. 2. The seamless belt according to claim 1, wherein fine metal powder is dispersed and blended in the outer peripheral surface layer of the seamless belt. 3. The seamless belt according to claim 1, further comprising a plating layer on the outer peripheral surface of the seamless belt.