JP3215230B2 - Composite tubular object - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a facsimile,
The present invention relates to a composite tubular article that can be used for a fixing belt of an image forming apparatus such as a printer.

[0002]

2. Description of the Related Art As a fixing method of an image on a transfer paper in an image forming apparatus, a heat roll fixing method, a flash fixing method, an oven fixing method, a pressure fixing method, and the like have been conventionally known. A belt fixing method using an (endless belt) has been proposed and employed in some apparatuses.

In this belt fixing method, for example, as shown in FIG. 1, a fixing belt 3 is wound around two rolls 1 and 2 (one is a driving roll) and a fixing heater 4, and is applied to the heater 4. The pressure rolls 5 are arranged facing each other,
By passing the transfer paper 6 between the fixing belt 3 and the pressure roll 5, the heat-sensitive ink 7 is melted and fixed, and the fixing by the pressure of the pressure roll 5 is strengthened. Is formed.

As a fixing belt in such a belt fixing method, for example, Japanese Patent Application Laid-Open No.
A composite tubular article comprising a polyimide resin tubular inner layer proposed in Japanese Patent No. 30149 and a fluororesin tubular outer layer formed on the outer peripheral surface thereof can be used.

In this belt fixing method, since the fixing belt is a thin material, the time from the start of heating of the fixing heater to the temperature at which the belt surface reaches the temperature at which the thermal ink can be fixed (the melting temperature of the thermal ink) can be reduced to several seconds or less. . This is a drastic reduction in time as compared with the conventional method (for example, about 20 seconds to 10 minutes in the hot roll fixing method). Therefore, the copier employing the belt fixing method has substantially no waiting time from the time of turning on the power to the start of copying (the time is offset by the time required from paper input to fixing). Copying can be started, so that it is not necessary to keep the power on all the time as in the conventional copying machine. This has the advantage of reducing power consumption and contributing to energy saving.

[0006]

When the belt fixing method is used in an image forming apparatus having a high fixing speed (for example, a copying machine having a high copying speed in a copying machine),
Excellent durability is required for the fixing belt. This is because a device having a high fixing speed is generally a high-grade system, and is frequently used until the end of the life of the device. Therefore, the fixing belt, which is a component of the device, can withstand a high frequency of use. Durability is required.

In the belt fixing method, the outer peripheral surface of the fixing belt is worn by the passage of paper. It has been empirically known that the belt wear phenomenon is particularly severe at the paper-wood end passing portion.

As described above, as a fixing belt for the belt fixing method, a composite tubular article comprising a polyimide resin tubular inner layer and a fluororesin tubular outer layer is known, and the outer peripheral surface of the composite tubular article belt, namely, In order to improve the durability of the fluororesin tubular outer layer, it is conceivable to increase the thickness of the fluororesin layer to extend the usable time (life), but it is not advisable to adopt this method. The reason is that increasing the thickness of the fluororesin layer inevitably increases the time from the start of heating of the fixing heater to the temperature at which the belt surface reaches the temperature at which the thermal ink can be fixed. The advantage of the law is reduced or lost.

Therefore, the present invention is to improve the durability, that is, the abrasion resistance, without increasing the thickness of the fluororesin layer in a composite tubular article having a polyimide resin tubular inner layer and a fluororesin tubular outer layer. With the goal.

[0010]

According to the present invention, as a result of intensive studies to solve the above-mentioned problems of the prior art, it has been found that a tubular outer layer is made of a specific fluororesin and that the fluororesin has specific properties. As a result, the present inventors have found that the object can be achieved, and have completed the present invention.

That is, the present invention is a composite tubular article having a polyimide resin tubular inner layer and a fluororesin tubular outer layer formed on the outer peripheral surface thereof, wherein the tubular outer layer has a melt viscosity at 380 ° C. of 1 × 10 ^5. or in which tetrafluoroethylene - Pa - Ri consists fluoroalkyl vinyl ether copolymer, the following conductive material particle size 5μm to said tubular outer min
And the surface resistance of the tubular outer layer is 10 ¹⁰ Ω / □ or less.
The present invention relates to a composite tubular article characterized by the following.

The inner layer of the composite tubular article according to the present invention as the inner layer made of a polyimide resin (thickness is not limited.
Can be used without any limitation as long as it is made of a polyimide resin, but a seamless type is preferable.

As described in Japanese Patent Application Laid-Open No. 3-130149, for example, a seamless type tubular article made of a polyimide resin is provided in a cylinder made of a heat-resistant material such as glass, metal or the like. Precursor) solution is supplied, and then a polyamic acid solution is applied to the inner peripheral surface of the cylinder by running a bullet or spherical body made of metal, plastic, glass, etc. in the cylinder, and then heated to remove the solvent. It can be obtained by a method of removing the polyamic acid and converting the polyamic acid into an imide to form a polyimide resin tubular article, which is removed from the cylinder. Synthesis of the polyamic acid used here, application of the polyamic acid solution to the inner peripheral surface of the cylinder, imide conversion by heating of the applied polyamic acid solution, inner peripheral surface of the polyimide resin tubular article formed on the inner peripheral surface of the cylinder The taking out of the tube is also described in detail in the official gazette, and a polyimide resin tubular article can be obtained based on these descriptions.

The composite tubular article according to the present invention comprises a fluororesin tubular layer formed on the outer peripheral surface of such a polyimide resin tubular article as the inner layer (this thickness is also not limited. , About 1-20 μm). This tubular outer layer must be formed from a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (hereinafter, referred to as “PFA”), and the PFA has a melt viscosity at 380 ° C. of 1 × 10 ^5.
Must be more than Poise. Note that this PF
The upper limit of the melt viscosity of A at 380 ° C. is not particularly limited, but is usually 1 × 10 ¹⁰ poise.

As described above, in the present invention, it is important that the tubular outer layer is formed of PFA and that the PFA having the above-mentioned physical properties is used.
If the tubular outer layer is formed of a fluororesin other than the above, or if the tubular outer layer is formed of PFA having a melt viscosity lower than the above value, the intended purpose of improving the wear resistance of the tubular outer layer cannot be achieved.

PFA is applied to the outer peripheral surface of the polyimide resin tubular material.
The method of forming the tubular layer need not be exceptional,
For example, a method in which a PFA dispersion is applied to the outer peripheral surface of a tubular member made of a polyimide resin, and then heated.

PFA on the outer peripheral surface of a polyimide resin tube
The application of the dispersion can be performed by a method of dipping the tubular article in the PFA dispersion, a spray coating, a brush coating, or the like. When the application of the PFA dispersion to the outer peripheral surface of the polyimide resin tubular article is performed by the dipping method, the dispersion adheres to the inner peripheral face of the tubular article, so that it is wiped off after the application. Of course, a detachable protective material such as an adhesive tape may be temporarily attached to the inner peripheral surface of the tubular object in advance to prevent the dispersion from adhering during immersion, and may be detached after immersion. It has been found that the PFA dispersion used in such a coating operation preferably has a viscosity of about 0.1 to 100 poise and a solid concentration of about 5 to 80% by weight from the viewpoint of workability.

Since a fixing belt of a copying machine or the like preferably has conductivity, it is possible to work by dispersing a conductive substance in a PFA dispersion.
In this way, the PFA tubular outer layer having conductivity (the surface resistance of the outer layer is preferably set to 10 ¹⁰ Ω / □ or less).
Can be formed. As the conductive substance, conductive powders such as carbon, graphite, and metal powders, conductive organic compounds and inorganic compounds, and the like can be used. When these conductive substances are used, the particle size is preferably about 5 μm or less from the viewpoint of dispersibility with PFA, and the amount of addition is preferably PF to maintain the mechanical strength of the tubular outer layer made of PFA.
Preferably, the amount is about 50 parts by weight or less based on 100 parts by weight of A.

Further, another fluororesin powder may be mixed in the PFA dispersion. In this case, the mixing amount of the other fluororesin powder is set to about 30 parts by weight or less based on 100 parts by weight of PFA. If the amount of the other fluororesin powder is too large, the purpose of improving the wear resistance may not be improved. As other fluororesin, use is made of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, PFA having a melt viscosity at 380 ° C. lower than 1 × 10 ⁵ poise, or the like. be able to.

Furthermore, a polyimide resin tubular inner layer and PFA
Prior to the application of the PFA dispersion, the outer peripheral surface of the inner layer is treated with alkali, ultrasonic, primer, sputter etching, corona discharge, plasma, and ultraviolet irradiation in order to improve the bonding strength with the outer tubular layer. A known bonding treatment such as laser treatment can be applied.

After the PFA dispersion is applied to the outer peripheral surface of the polyimide resin tubular article as described above, it is heated to form a PFA tubular outer layer. This heating operation may be performed by a one-step heating method in which the polyimide resin tubular article coated with the fluororesin dispersion is heated to a temperature equal to or higher than the melting point of PFA. Lower temperature) to remove the dispersion medium, and then to a two-stage heating method or the like in which the dispersion medium is heated to a temperature equal to or higher than the melting point of PFA.

[0022]

The present invention will be described in more detail with reference to the following examples. In Examples and Comparative Examples, pyromellitic dianhydride was “PMDA” and 3,3 ′, 4,4′-.
Biphenyltetracarboxylic dianhydride is "BPDA"
And 4,4′-diaminodiphenyl ether are “DD
E "and p-phenylenediamine are abbreviated as" PDAs ", respectively.

Example 1 Equimolar amounts of PMDA and DDE were placed in a flask with N-methyl-
The polyamic acid solution was dissolved in 2-pyrrolidone (NMP) (the concentration of the total weight of both monomers in the solution was 20% by weight), and reacted under stirring in a nitrogen gas atmosphere while maintaining the temperature at 20 ° C. for 5 hours. obtain. The rotational viscosity (measured by a B-type viscometer) of this polyamic acid solution was 25,000 poise, and the logarithmic viscosity [η] was 2.9 (measured by a capillary viscometer at a temperature of 30 ° C.). next,
The polyamic acid solution is heated to 50 ° C. for aging, and the rotational viscosity is adjusted to 1500 poise.

On the other hand, a PF having a melt viscosity at 380 ° C. (measured with a flow tester) of 5 × 10 ⁵ poise
An aqueous dispersion of A powder (50% by weight of PFA) and an aqueous dispersion of carbon powder having an average particle diameter of 0.3 μm (carbon concentration of 16.5% by weight) are mixed by the same weight to obtain PFA having conductivity. Obtain an aqueous dispersion. The mixing ratio of PFA and carbon in the conductive dispersion was PFA1
4 parts by weight of carbon to 00 parts by weight.

Then, the polyamic acid solution whose viscosity has been adjusted is supplied to the opening at one end of a cylindrical stainless steel cylinder having an inner diameter of 50 mm, a thickness of 5 mm, and a length of 500 mm. Polyamide acid is applied to the inner peripheral surface of the cylinder by causing a bullet-shaped body having an outer diameter of 49.4 mm to travel downward by its own weight. The inner peripheral surface of the stainless steel cylinder was adjusted so that the surface roughness (Rz) became 2 μm.

After application, the cylinder is heated at 70 ° C. for 60 minutes, then heated to 300 ° C., and further heated at this temperature for 60 minutes.
By heating for one minute, NMP and ring-closing water are removed and imide conversion is performed to form a polyimide resin tube. Next, air is pressure-fed from a small through hole provided in advance at one end of the cylinder, and the polyimide resin tubular material is peeled off from the inner peripheral surface of the cylinder and taken out. This tubular article had a length of about 500 mm, an outer diameter of 50 mm, and a thickness of 30 μm.

This polyimide resin tubular article is immersed in the above-mentioned conductive dispersion, pulled up, and air-dried for 10 minutes to wipe off the dispersion adhered to the inner peripheral surface. Then, the mixture was heated at 100 ° C. for 10 minutes to remove water as a dispersion medium, and then heated at 400 ° C. for 5 minutes to obtain a composite tubular article having a PFA tubular outer layer having conductivity. The PAF tubular outer layer in this composite tubular material has a thickness of 10 μm, a surface roughness (Rz) of 4.0 μm, and a surface resistance (measured by Hiresta IP, manufactured by Mitsubishi Yuka Co., Ltd.) 2 ×
It was 10 ⁶ Ω / □.

The composite tubular article was cut into a width of 300 mm to form a fixing belt, which was incorporated into an image fixing apparatus, whereby a system having a good offset property was obtained. When a continuous paper passing test was performed using this image fixing device, the wear depth of the PFA tubular outer layer at the end of 200,000 sheets (the thickness of the PFA tubular outer layer removed by abrasion) was the largest. It was as small as 3.5 μm at each location, and there was no problem with the offset property at that time.

Example 2 Instead of PMDA and DDE, BPDA and PDA
Except that the rotational viscosity was 35,000 in the same manner as in Example 1.
A polyamic acid solution having a poise and logarithmic viscosity [η] of 3.2 is obtained, and this solution is heated to 50 ° C. to adjust the rotational viscosity to 1500 poise.

Using this polyamic acid solution whose viscosity has been adjusted, a length of about 500 mm and an outer diameter of 50 are used in the same manner as in Example 1.
A polyimide resin tube having a thickness of 30 mm and a thickness of 30 mm is obtained.

Actually, the outer peripheral surface of the polyimide resin tube is
The same conductive dispersion as used in Example 1 was applied to the air.
-Apply with a spray gun, air dry for 10 minutes,
Heat at 0 ° C for 10 minutes and then at 400 ° C for 10 minutes
To provide a conductive PFA tubular outer layer.
A composite tubular article was obtained. PFA in this composite tubing
The tubular outer layer was 10 μm thick and had a surface roughness (Rz) of 4.3 μm.
m, surface resistance 4 × 10 ⁶Ω / □.

By incorporating this composite tubular material into an image fixing device as a fixing belt in the same manner as in Example 1, a system with good offset properties could be obtained. Also,
When a continuous paper passing test was performed using this image fixing device, the wear depth of the tubular outer layer made of PFA at the end of 200,000 sheets was as small as 3.3 μm at the maximum point, and the offset property at that point was low. There was no problem.

Example 3 As an aqueous dispersion of PFA, a PFA powder having a melt viscosity at 380 ° C. of 3 × 10 ⁵ poise was used at a concentration of 50.
The same procedure as in Example 1 was carried out except that the dispersion was performed so as to obtain a composite tube having a weight% by weight, to obtain a composite tube comprising a polyimide resin tube inner layer and a conductive PFA tube outer layer. The PFA tubular outer layer in this composite tubular article had a thickness of 10 μm, a surface roughness (Rz) of 3.9 μm, and a surface resistance of 3 × 10 ⁶ Ω / □.

By incorporating this composite tubular article into an image fixing device as a fixing belt in the same manner as in Example 1, a system having good offset properties could be obtained. Also,
When a continuous paper passing test was performed using this image fixing device, the wear depth of the tubular outer layer made of PFA at the end of 200,000 sheets was as small as 4.5 μm at the maximum point, and the offset property at that time was poor. There was no problem.

Example 4 As an aqueous dispersion of PFA, a PFA powder having a melt viscosity at 380 ° C. of 3 × 10 ⁵ poise was used at a concentration of 50.
A composite tubular article comprising a polyimide resin tubular inner layer and a conductive PFA tubular outer layer was obtained in the same manner as in Example 2 except that the dispersion was performed so as to be in a weight percentage. The PFA tubular outer layer in this composite tubular article has a thickness of 10 μm, a surface roughness (Rz) of 4.2 μm, and a surface resistance of 1 ×.
It was 10 ⁶ Ω / □.

By incorporating this composite tubular material into an image fixing device as a fixing belt in the same manner as in Example 1, a system with good offset properties could be obtained. Also,
When a continuous paper passing test was performed using this image fixing device, the wear depth of the tubular outer layer made of PFA at the end of 200,000 sheets was as small as 4.1 μm at the maximum, and the offset property at that time was also low. There was no problem.

Comparative Example 1 As an aqueous dispersion of PFA, a PFA powder having a melt viscosity at 380 ° C. of 7 × 10 ⁴ poise was used at a concentration of 50.
A composite tubular article comprising a polyimide resin tubular inner layer and a conductive PFA tubular outer layer was obtained in the same manner as in Example 1 except that the dispersion was performed so as to be 0.1% by weight. The PFA tubular outer layer in this composite tubular article has a thickness of 10 μm, a surface roughness (Rz) of 3.5 μm, and a surface resistance of 8 ×.
It was 10 ⁵ Ω / □.

By incorporating this composite tubular article into an image fixing device as a fixing belt in the same manner as in Example 1, a system with good offset properties could be obtained. However, in the continuous paper passing test of this image fixing device, at the end of 150,000 sheets, the tubular outer layer made of PFA disappeared due to abrasion at the end of the paper and the polyimide resin layer was exposed.
Also, the offset property was poor.

Comparative Example 2 As an aqueous dispersion of PFA, a PFA powder having a melt viscosity at 380 ° C. of 3 × 10 ⁴ poise at a concentration of 50 was used.
A composite tubular article comprising a polyimide resin tubular inner layer and a conductive PFA tubular outer layer was obtained in the same manner as in Example 2 except that the dispersion was performed so as to be in a weight percentage. The PFA tubular outer layer in this composite tubular article has a thickness of 10 μm, a surface roughness (Rz) of 3.3 μm, and a surface resistance of 4 ×.
It was 10 ⁵ Ω / □.

By incorporating this composite tubular article into an image fixing device as a fixing belt in the same manner as in Example 1, a system having good offset properties could be obtained. However, in the continuous paper passing test of this image fixing apparatus, at the end of 120,000 sheets, the tubular outer layer made of PFA disappeared due to abrasion at the paper sheet edge passing portion, and the polyimide resin layer was exposed.
Also, the offset property was poor.

[0041]

According to the present invention, since the tubular outer layer is formed of PFA having a melt viscosity at 380 ° C. of 1 × 10 ⁵ poise or more, the tubular outer layer is excellent in abrasion resistance of the tubular outer layer. Can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an actual example of a belt fixing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roll 2 Roll 3 Fixing belt 4 Fixing heater 5 Pressure roll 6 Transfer paper 7 Thermal ink 8 Image

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-110137 (JP, A) JP-A-2-43046 (JP, A) JP-A-5-112690 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 G03G 15/20

Claims (1)

(57) [Claims] 1. A composite tubular article having a polyimide resin tubular inner layer and a fluororesin tubular outer layer formed on its outer peripheral surface, wherein the tubular outer layer has a melt viscosity at 380 ° C. of 1
Tetrafluoroethylene is × 10 ⁵ or more - Pa - Ri consists fluoroalkyl vinyl ether copolymer, tubular
A conductive material having a particle size of 5 μm or less is dispersed in the outer layer,
A composite tubular article characterized in that the outer surface of the tubular layer has a surface resistance of 10 ¹⁰ Ω / □ or less .