JP2953141B2 - Conductive 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 conductive seamless belt used for an intermediate transfer device such as an electrophotographic copying machine and a laser printer, a transfer separation device, and a charging device.

[0002]

2. Description of the Related Art Conventionally, endless belts are frequently used in intermediate transfer devices, transfer separation devices, charging devices and the like of electrophotographic copying machines. FIG. 1 is a plan view of the intermediate transfer device. In the figure, 1 is a photosensitive drum, and 6 is a conductive seamless belt. Around the photosensitive drum 1, a charger 2,
An electrophotographic process unit including an exposure optical system 3 using a semiconductor laser or the like as a light source, a developing device 4 containing toner, and a cleaner 5 for removing residual toner is arranged.

[0003] The conductive seamless belt 6 is stretched over conveying rollers 7, 8, 9 and moves in the direction of the arrow in synchronization with the photosensitive drum rotating in the direction of the arrow. Regarding this operation, first, the surface of the photosensitive drum 1 rotating in the direction of the arrow is uniformly charged by the charger 2. Next, an electrostatic latent image is formed thereon by the optical system 4, and the latent image is developed by the developing device 4. The toner image formed by this development is electrostatically transferred to the conductive seamless belt 6 by the electrostatic transfer device 10.

[0004] The toner image transferred onto the belt is conveyed by conveying rollers 7, 8 and 9, and is transferred to recording paper 11 between conveying roller 9 and pressing roller 12. By the way, in the case of an intermediate transfer belt or the like, the toner always adheres to the function, and in the case of the transfer separation belt or the like, the function is not intended to adhere the toner. Therefore, it is necessary to remove the adhered residual toner from the belt.

However, the toner adhering to the belt can be easily removed at an early stage of use, but the toner adheres to the surface of the belt in the form of a film with the lapse of use and cannot be easily removed. It is known that the toner sticking, which is called filming development, can be prevented by using a belt made of a fluorine-based resin that is incompatible with the toner.

However, since polytetrafluoroethylene resin, which is a typical fluorine resin, has a low tensile modulus, in the case of a single-layer belt made of only polytetrafluoroethylene resin, the belt is stretched during use. There is a problem that image spots occur. In order to reinforce this low elastic modulus, it is conceivable to laminate a polytetrafluoroethylene-based resin on the surface of a base material belt such as a polycarbonate-based resin that does not easily stretch. However, since the polytetrafluoroethylene resin cannot be melt-kneaded in an extruder, the polytetrafluoroethylene resin must be dissolved in a solvent, applied to the surface of the base belt, and baked at a high temperature of about 200 ° C. or higher. Since the base material belt is deformed and deteriorated by heat, there are problems such as occurrence of image unevenness and cracking of the belt, thereby impairing durability.

A polyvinylidene fluoride resin, which is a thermoplastic fluororesin, has a high modulus of elasticity and thus does not have a problem of elongation, but has low impact resistance and is easily torn (Japanese Patent Laid-Open No. 2-106530).
Therefore, the method cannot be used as a single-layer belt.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an intermediate device for electrophotographic copying machines, laser printers, etc., which is hardly stretched, hardly deforms, hardly causes cracks, has durability and does not cause filming phenomenon. An object of the present invention is to provide a conductive seamless belt that can be used for a transfer device, a transfer separation device, a charging device, and the like.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the conventional problems, the present inventors have found that by laminating two specific types of conductive resins, more preferably, three specific types of conductive resins are laminated. By laminating a conductive resin, it has been found that a belt that is hard to stretch, hard to deform, hard to crack, has durability, and does not cause a filming phenomenon can be obtained, and has reached the present invention. .

[0010]

More specifically, the present invention provides a multilayer structure comprising a conductive polyvinylidene fluoride resin layer and a conductive acrylic resin layer, wherein the conductive polyvinylidene fluoride resin layer is a surface layer. A conductive seamless belt is provided.

[0011]

DETAILED DESCRIPTION OF THE INVENTION

 (1) Conductivity The conductivity of the seamless belt is 10^Five-10¹³Ω / □, good
Preferably 10⁶-10 ¹¹Ω / □ range and the purpose
It is preferable that the conductivity value is within ± 1 order. Conductive
Sex is 10^FiveWhen it is less than Ω / □, the charge on the belt
Leakage occurs, and in the case of an intermediate transfer belt, the toner
Cannot be transferred efficiently. Also, 10¹³Ω / □
If it exceeds, the conductivity will be poor, and the process after charging will be short.
It becomes difficult to eliminate electricity between the two.

(2) Polyvinylidene fluoride resin The polyvinylidene fluoride resin used in the present invention includes not only a homopolymer of vinylidene fluoride but also vinylidene fluoride in an amount of 50% by weight or more, preferably 70% by weight or more. In addition to copolymers containing at least 85% by weight, particularly preferably at least 85% by weight, blends of at least 60% by weight of these polymers and at most 40% by weight of other resins can be mentioned. As a comonomer component in the case of a copolymer, propylene hexafluoride, ethylene tetrafluoride, or the like can be used. Other resins in the case of blending include acrylic resins such as polymethyl methacrylate and ethylene / alkyl acrylate copolymer. Fillers, stabilizers, pigments, and the like may be further added to these polyvinylidene fluoride resins as long as the effects of the present invention are not significantly impaired. Melt flow rate (MFR) of polyvinylidene fluoride resin is 0.3 ~
12.0 g / 10 minutes is preferred, and particularly 1.0 to 4.0 g.
/ 10 minutes is preferred.

(3) Acrylic resin The acrylic resin used in the present invention is an acrylate resin, which is a homo- or copolymer of alkyl acrylate and / or alkyl methacrylate, or a monomer containing these monomers. (50% by weight or more)
In addition to copolymers of this with other monomers, blends of 60% by weight or more of these polymers and 40% by weight or less of other resins can be mentioned.

Specifically, it is a homo- or copolymer of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate and the like, preferably a homopolymer of methyl methacrylate or ethyl methacrylate or a homo- or copolymer thereof. A copolymer with another alkyl acrylate containing a monomer as a main component is preferred, and a butyl acrylate copolymer is particularly preferred.

[0015] Fillers, stabilizers, pigments and the like may be further added to these acrylic resins as long as the effects of the present invention are not significantly impaired. MFR of acrylic resin is 0.3
To 6.0 g / 10 min, particularly preferably 1.5 to 3.0 g
/ 10 minutes is preferred.

(4) Polycarbonate Resin In the present invention, a polycarbonate resin can be laminated as an inner layer. The polycarbonate-based resin is an aromatic polycarbonate resin in which at least most of the dihydroxy compound to constitute a carbon ester has two phenolic hydroxyl groups. Specific examples of such a dihydric phenol include bisphenols such as bisphenol A, bisphenol F, and bisphenol S, particularly bisphenol A.

The aromatic polycarbonate is produced by reacting the above-mentioned dihydric phenol with phosgene, a bischloroformate, a carbonic acid diester or the like, which is a carbonate bridger. Up to 30% by weight of a polyalkylene terephthalate resin can be mixed with the polycarbonate resin. As the polyalkylene terephthalate resin, there are a polyethylene terephthalate resin and a polybutylene terephthalate resin, and a polybutylene terephthalate resin is preferable.

(5) Providing Conductivity In the present invention, in order to impart conductivity to each layer, when laminating a polyvinylidene fluoride resin, an acrylic resin, or a polycarbonate resin, a conductive filler is also added to the polycarbonate resin. Obtained by mixing. As the conductive filler used in the present invention, at least one selected from carbon black, graphite, carbon fiber, metal powder, conductive metal oxide, organometallic compound, organic metal salt, conductive polymer, or the like, What consists of these mixtures is preferable.

Among them, carbon black is preferred. As carbon black, acetylene black,
There are furnace black and channel black. The surface layer and the inner layer are preferably acetylene black having good dispersibility so as not to impair the appearance of the seamless belt. The acetylene black preferably has a particle size of 10 to 1,000 angstroms and a specific surface area of 10 to 150 m ² / g.

The compounding amount of carbon black is 7 to 30 parts by weight, preferably 10 to 25 parts by weight based on 100 parts by weight of each resin. As for the method of compounding the conductive filler into each resin, pellets can be formed by applying a usual melt-kneading method, that is, a single-screw extruder, a twin-screw extruder, a roll, a Banbury or the like.

In the kneading, it is necessary to sufficiently control the water content of each component. The water content of each component is 0.5% by weight or less, preferably 0.2% by weight or less,
In particular, it is preferably 1000 ppm or less. In the case of a polycarbonate-based resin, if the water content exceeds 0.5% by weight, the polycarbonate-based resin is hydrolyzed during melt-kneading, which may adversely affect the appearance of the product. Care must be taken in the storage of the composition after production, and it is preferable to control the water content of the composition itself to 0.5% by weight or less. For this reason, means such as hot-air drying or reduced-pressure drying are employed as necessary.

(6) Method of Manufacturing Seamless Belt As a method of manufacturing a seamless belt, a continuous melt extrusion molding method is desirable. The injection molding method or the blow molding method is a discontinuous intermittent molding method.Belts formed by these molding methods have a non-uniform melt orientation state in the longitudinal direction orthogonal to the belt circumferential direction. Becomes uneven in the width direction of the belt, making it difficult to control the order of ± 1.

As a desirable continuous melt extrusion molding method of the seamless belt of the present invention, when the diameter of the belt is 30 mmφ or more, for example, the inner diameter of the extruded tube, which is a method described in JP-A-1-228823, is used. What is necessary is just to employ | adopt the internal cooling mandrel system of the downward extrusion system which can be controlled with high precision. The belt diameter is 30mmφ
If smaller, a vacuum sizing method may be adopted.

The extruded tube must be unstretched and have the required conductivity, uniform thickness, mechanical strength, and crack resistance. When the stretching operation is performed, the mechanical strength can be expected to be improved, but the uniformity of conductivity is impaired, and the film is easily torn in the stretching direction, so that the crack resistance is impaired. Further, the stretching causes peeling at the interface between the carbon black and the plastic, causing the carbon to fall off and causing uneven transfer.

A method for manufacturing a conductive seamless belt having a laminated structure composed of a conductive polyvinylidene fluoride resin layer, a conductive acrylic resin layer, and a conductive polycarbonate resin layer as required is described below. It is preferable to adopt a co-extrusion method in which the layers are laminated in a molten state in a stand die and then continuously melt-extruded. If necessary, another resin layer may be provided between the surface layer and the intermediate layer, or between the intermediate layer and the inner layer.

(7) Seamless Belt The thickness of the obtained seamless belt is 30 μm or more and 1,000 μm or less. Preferably, it is 50 μm or more and 500 μm or less. When the thickness is less than 30 μm, the seamless belt is easily stretched, which causes problems such as uneven color of an image. In addition, the withstand voltage is insufficient, so that a voltage sufficient to impart a charge necessary for transfer cannot be applied.
On the other hand, if the thickness exceeds 1,000 μm, flexible deformation becomes difficult, so that driving at a uniform speed by a small-diameter roll is impaired, an image is displaced, and the capacitance is reduced. Therefore, not only the cost is increased due to the necessity of a large-scale high-voltage power supply unit than necessary, but also a problem such as discharge between peripheral equipment parts is likely to occur because high voltage is applied.

The ratio of the thickness of the three layers of the surface layer, the intermediate layer, and the inner layer is as follows: surface layer / intermediate layer = 1/1 to 4/1, and surface layer / inner layer =
1/1 to 1/10 is preferred. If the surface layer is thicker than this ratio, cracks are likely to be formed by continuous driving with a small-diameter roll. When the intermediate layer is thinner than this ratio, sufficient adhesive strength cannot be obtained, and the surface layer and the inner layer are easily peeled off during use.

The seamless belt may be used as it is, or may be wound around a drum or the like. Further, for the purpose of preventing meandering, reinforcing the end surface, and the like, the end surface of the belt having a predetermined size may be treated with a heat-resistant tape or silicone rubber.

[0029]

EXAMPLES Various evaluations and measurements in the following Examples and Comparative Examples were conducted by the following methods. (1) Conductivity (Surface conductivity: Ω / □) Evaluated using a surface conductivity meter Hiresta, □ Resta (trade name, manufactured by Mitsubishi Yuka Co., Ltd.) at a measurement voltage of 100 V and a measurement time of 10 seconds. (2) Conductivity distribution According to the conductivity measurement method of (1), the belt was measured at a pitch of 30 mm in the circumferential direction and the longitudinal direction. . (3) Durability A 200 mm wide seamless belt is rolled with a roll diameter of 25 φm.
m, roll speed 100 mm / sec, belt tension 2 kg / belt width, 25 ° C, 55%
Even when the belt substrate was continuously operated for 50 hours, an abnormality such as cracks and peeling between the layers was not observed in the belt base material, and a case where abnormalities were observed was evaluated as x. (4) Filming aptitude The sharpness of the image was evaluated using the apparatus shown in FIG.
If the image is clear with no transfer omission, color shift, blur,
A case where transfer omission or the like occurred was evaluated as x.

(Example 1) Melt flow rate (MF)
R) 2 g / 10 min (230 ° C.) polyvinylidene fluoride resin [Kyner 720 (trade name) manufactured by Penwort] 1
To 100 parts by weight, 14 parts by weight of acetylene black (manufactured by Denki Kagaku KK) having a specific surface area of 70 m ² / g were kneaded and granulated at 220 ° C. using a twin-screw extruder equipped with a vent to obtain a conductive polyvinylidene fluoride resin. I got

A methyl methacrylate resin having an MFR of 1.5 g / 10 minutes (230 ° C.) [HB manufactured by Mitsubishi Rayon Co., Ltd.]
S-001 (trade name)]
m ² / g acetylene black [manufactured by Denki Kagaku] 14
The weight part was kneaded and granulated at 200 ° C. using a vented twin-screw extruder to obtain a conductive acrylic resin. MFR is 5g / 10
(280 ° C) polycarbonate resin [Iupilon E-2000 (trade name) manufactured by Mitsubishi Gas Chemical Co., Ltd.] 83 parts by weight, polybutylene terephthalate having an MFR of 4 g / 10 minutes (230 ° C) [manufactured by Mitsubishi Kasei Corporation Novador 5020
(Trade name)] 17 parts by weight and 14 parts by weight of acetylene black (manufactured by Denki Kagaku Co., Ltd.) having a specific surface area of 70 m ² / g were kneaded and granulated at 270 ° C. using a vented twin-screw extruder to obtain a conductive polycarbonate. A system resin was obtained.

The mixed and granulated conductive polyvinylidene fluoride-based resin was applied to a surface layer by an extruder having a diameter of 40 mm.
Extruded at 200 ° C from a 25 mmφ extruder to extrude the mixed and granulated conductive acrylic resin at 200 ° C to form an intermediate layer, and from a 40φ extruder to form the mixed and granulated conductive polycarbonate resin as an inner layer. Extruded at 270 ° C, 2
Each of the three layers is co-extruded at 65 ° C. into a 140 mmφ three-layer co-extrusion circular die, and after being laminated in the die, extruded in a state of a molten tube below the circular die, and the extruded molten tube is supported on the same axis of the circular die. 130 mounted via
After contacting the outer surface of the cooling mandrel with a diameter of mm to be cooled and solidified to form a seamless tube, the surface layer / intermediate layer / inner layer = 30 / with a core installed in the seamless tube and a roll installed outside. A 30/90 μm seamless tube having a total thickness of 150 μm (seamless belt cut to a predetermined length) was taken out while holding the cylinder. The obtained belt was evaluated for thickness, conductivity, conductivity distribution, durability and filming suitability. Table 1 shows the evaluation results.

(Comparative Example 1) The conductive polyvinylidene fluoride resin obtained by mixing and granulating in Example 1 was extruded at 200 ° C. from respective extruders of 40 mmφ, 25 mmφ, and 40 mmφ of the surface layer, the intermediate layer and the inner layer. Example 1 was repeated except that the extrusion was conducted to a three-layer co-extrusion annular die of 140 mmφ at 200 ° C.
A 150 μm seamless tube was obtained in the same manner as described above.
Table 1 shows the evaluation results of the obtained seamless belt.

Comparative Example 2 The conductive polycarbonate resin obtained by mixing and granulating in Example 1 was extruded at 270 ° C. from respective extruders of 40 mmφ, 25 mmφ, and 40 mmφ of the surface layer, the intermediate layer, and the inner layer. Example 1 except that the three-layer co-extrusion die of 140 mmφ at 140 ° C. was led respectively.
A 150 μm seamless tube was obtained in the same manner as described above.
Table 1 shows the evaluation results of the obtained seamless belt.

Comparative Example 3 The conductive polyvinylidene fluoride resin obtained by mixing and granulating in Example 1 was used as the surface layer
The conductive polycarbonate resin extruded at 200 ° C. from an extruder of mmφ and mixed and granulated in Example 1 was used as an intermediate layer.
270 from the extruder of 25mmφ and 40mmφ respectively for the inner layer
Extruded at 265 ° C. and led to a 140 mmφ three-layer co-extruded annular die at 265 ° C., respectively, except that the surface layer / (intermediate layer + inner layer) = 50/100 μm total thickness 150
A μm seamless tube was obtained. Table 1 shows the evaluation results of the obtained seamless belt.

[0036]

[Table 1]

[0037]

By co-extruding a conductive resin comprising at least polyvinylidene fluoride and an acrylic resin into an annular film, it is hardly stretched, hardly deformed, hardly cracked, durable, and filled. A conductive seamless belt free from the occurrence of a mining phenomenon can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of an intermediate transfer device of an electrophotographic copying machine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive drum 2 charger 3 exposure optical system 4 developing device 5 cleaner 6 conductive seamless belt 7 transport roller 8 transport roller 9 transport roller 10 electrostatic transfer unit 11 recording paper 12 pressure roller

Claims (2)

(57) [Claims] 1. A conductive seamless belt having a multilayer structure comprising a conductive polyvinylidene fluoride resin layer and a conductive acrylic resin layer, wherein the conductive polyvinylidene fluoride resin layer is a surface layer. 2. A conductive seamless belt having a multilayer structure in which a conductive polyvinylidene fluoride resin layer is used as a surface layer, a conductive acrylic resin layer is used as an intermediate layer, and a conductive polycarbonate resin layer is used as an inner layer.