JPH06114973A - Seamless belt - Google Patents

Abstract

PURPOSE:To prevent a filming phenomenon and improve durability by forming a seamless belt from a compsn. consisting of an ethylene/tetrafluoroethylene copolymer having a specific melt flow rate and carbon black and specifying the surface conductivity of both surfaces of the belt. CONSTITUTION:A seamless belt is formed from a compsn. consisting of 97-75wt.% of an ethylene/tetrafluoloethylene copolymer with a melt flow rate of below 8g/10min and 3-25wt.% of carbon black and the surface conductivity of both surfaces of the belt is set to 1X10<0>-1X10<13>OMEGA/square. The electrostatic latent image corresponding to an image is formed on a photosensitive drum 1 by an optical system and developed by a developer 4 to form a toner image which is, in turn, electrostatically transferred to the conductive seamless belt 6 by an electrostatic transfer device 10 to be transferred to recording paper 11 between a feed roller 9 and a press roller 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seamless belt used for an electrophotographic copying machine, a laser printer, etc., for use as a photoreceptor substrate, intermediate transfer, conveyance, fixing and development.

[0002]

2. Description of the Related Art Conventionally, endless belts, especially seamless belts, have been widely used in intermediate transfer devices, transfer separation devices, charging devices and the like of electrophotographic copying machines.
FIG. 1 is a side view of a main part of an intermediate transfer type copying machine. In the figure, 1 is a photosensitive drum, and 6 is a conductive seamless belt. Around the photosensitive drum 1, an electrophotographic process unit including a charger 2, an exposure optical system 3 using a semiconductor laser as a light source, a developing device 4 containing toner, and a cleaner 5 for removing residual toner is provided. It is arranged.

The electrically conductive seamless belt 6 is constructed so as to be stretched over the conveying rollers 7, 8 and 9 and move in the direction of arrow B in synchronization with the photosensitive drum rotating in the direction of arrow A. Next, the operation will be described. First, the surface of the photosensitive drum 1 rotating in the direction of arrow A is uniformly charged by the charger 2. Next, an electrostatic latent image corresponding to an image obtained by an image reading device (not shown) or the like is formed on the photosensitive drum 1 by the optical system 3. The electrostatic latent image is developed into a toner image by the developing device 4. This toner image is electrostatically transferred onto the conductive seamless belt 6 by the electrostatic transfer device 10, and transferred onto the recording paper 11 between the conveying roller 9 and the pressing roller 12.

As the conductive seamless belt, for example, a thermoplastic resin such as polycarbonate resin or polyethylene terephthalate is mixed with conductive carbon black, and a cylindrical film is extrusion-molded by using a cylindrical die. It is known that they are sliced into several pieces (disclosed in JP-A-2-233765, JP-A-3-89357 and JP-A-64-26439).

[0005]

High durability is required for seamless belts used in electrophotographic copying machines. However, in the polycarbonate-based seamless belt, the end faces are cracked in a short time and progress with time, leading to breakage. Further, in the case of intermediate transfer, transfer separation, etc., the toner (residual toner) that has not been transferred to the recording paper is repeatedly removed, so that toner removal characteristics are also required. However, residual toner adheres to the surface of the belt in a film form as the belt is used, and cannot be easily removed (filming phenomenon). The cause of the filming phenomenon is unknown, but it is believed that surface compatibility may affect it. As a resin that is incompatible with the toner, there is a fluorine-based resin such as polyvinylidene fluoride, but it has not been put to practical use in terms of impact resistance and durability.

[0006]

The inventors of the present invention have found that by using a fluorine-based resin that solves the conventional problems, a filming phenomenon can be prevented and a seamless belt having excellent durability can be realized. The present invention has been completed.
That is, according to the present invention, the melt flow rate is 8 g /
Consists of ethylene tetrafluoroethylene copolymer of less than 10min 97-75% by weight of carbon black 3-25% by weight, the surface conductivity of the surface and the back surface is 1 × 10 ⁰
It is possible to obtain a seamless belt which has a filming phenomenon of up to 1 × 10 ¹³ Ω / □ and which is excellent in durability.

The present invention will be specifically described below. (1) Ethylene tetrafluoroethylene copolymer The melt flow rate (MFR) of the ethylene tetrafluoroethylene copolymer used in the present invention is 8 g / 10.
It is preferably less than min and more preferably less than 5 g / 10 min. If the melt flow rate is 8 g / 10 min or more, the crack resistance becomes extremely poor and the durability becomes poor.

(2) Carbon Black As the carbon black used in the present invention, acetylene black, furnace black and channel black are preferable. (3) Compounding amount: 97-75% by weight of ethylene tetrafluoroethylene copolymer and 3-25% by weight of carbon black. If the amount of carbon black is less than 3% by weight, conductivity is poor,
If it exceeds 25%, problems such as deterioration of appearance of the product and reduction of strength occur.

The surface conductivity is 10⁰-10¹³Ω / □
Enclosure is preferred. When used as a photoreceptor substrate,
10⁰-10^FiveΩ / □ is preferable, 10⁰-10³Ω / □
Particularly preferred. Intermediate transfer, transport, fixing and development
10 when used for other purposes ^Five-10¹³Ω / □ is preferred
10⁷-10¹²Ω / □ is particularly preferable.

Further, in the present invention, in addition to these components, additional components can be blended within a range that does not significantly impair the effects of the invention. As the additional component and the thermoplastic resin, polypropylene, polyethylene (high density, medium density, low density, linear low density), propylene ethylene block or random copolymer, rubber or latex component such as ethylene / propylene copolymer Rubber, styrene / butadiene rubber, styrene / butadiene / styrene block copolymer or hydrogenated derivative thereof, polybutadiene, polyisobutylene, polyamide, polyamideimide, polyacetal, polyarylate, polycarbonate, polyphenylene ether, modified polyphenylene ether, polyimide, liquid crystal Polyester, polyethylene terephthalate, polysulfone, polyether sulfone, polyphenylene sulfide, polybisamide triazole, polybutylene terephthalate Polyether imide, polyether ether ketone, acrylic, polyvinylidene fluoride, polyvinyl fluoride, chlorotrifluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether copolymer, acrylic, acrylic acid alkyl ester copolymer, polyester ester copolymer A compound, a polyether ester copolymer, a polyether amide copolymer, a polyurethane copolymer, or the like, or a mixture thereof is used. A thermosetting resin, for example, an epoxy resin, a melamine resin, a phenol resin, an unsaturated polyester resin, or a mixture thereof is used.

Further, various fillers such as calcium carbonate (heavy, light and colloidal) talc, mica, silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, zinc oxide, zeolite, wollastonite, diatom Soil, glass fiber, glass beads, bentonite, montmorillonite, asbestos, hollow glass beads,
Graphite, molybdenum disulfide, titanium oxide, carbon fiber, aluminum fiber, stainless steel fiber, brass fiber, aluminum powder, wood powder, chaff, graphite, metal powder, conductive metal oxide, organic metal compound, organic metal salt,
In addition to fillers such as, etc., as additives: antioxidants (phenol-based, sulfur-based, etc.), lubricants, various organic / inorganic pigments,
UV absorber, antistatic agent, dispersant, neutralizing agent, foaming agent,
Examples thereof include a plasticizer, a copper damage inhibitor, a flame retardant, a cross-linking agent, and a flowability improver.

If desired, the above composition may contain additional components such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll,
It can be produced by using an ordinary kneader such as Brabender, Plastograph, and kneader. Normally, each component is kneaded with an extruder or the like to form a pellet-shaped compound, which is then processed.However, in a special case, each component is directly supplied to a molding machine and the composition is kneaded with the molding machine. It can also be molded.

As a method for producing the seamless belt, known methods such as a continuous melt extrusion molding method, an injection molding method or a blow molding method, and an inflation film molding method can be adopted. The preferred manufacturing method is continuous melt extrusion.
In particular, the internal cooling mandrel method or the vacuum sizing method of the downward extrusion method that can control the inner diameter of the extruded tube with high accuracy is preferable, and the internal cooling mandrel method is the most preferable.

The extruded seamless belt must have necessary conductivity, thickness uniformity and mechanical strength in an unstretched state. This is because the stretching operation can be expected to improve the mechanical strength, but there is a problem that the uniformity of conductivity is impaired, and the durability tends to be impaired due to easy tearing in the stretching direction. Further, there is a problem that peeling occurs at the interface between the carbon black and the plastic and the carbon falls off to cause uneven transfer.

The thickness of the seamless belt is preferably 50 μm or more and 1000 μm or less, and 100 μm or more and 700 μm or less.
It is more preferably m or less. If the thickness is less than 50 μm, the seamless belt is likely to be stretched, so that problems such as image color unevenness occur. In addition, the withstand voltage is insufficient, and it becomes impossible to apply a voltage sufficient to apply the charges required for transfer. Further, if it exceeds 1000 μm, it becomes difficult to flexibly deform, so that it is not possible to drive the roller with a small diameter at a uniform speed, and an image transfer deviation occurs. Furthermore, since the electrostatic capacity becomes small, it is not possible to apply the charge necessary for transfer unless a high voltage is applied, which not only increases the cost and size of the power supply device, but also causes the discharge between peripheral device parts. A problem arises.

The seamless belt may be used as it is as a belt or may be wound around a drum or a roll. Further, as shown in FIG. 2, for the purpose of preventing meandering and reinforcing the end surface, the inner side surface end portion of the seamless belt having a predetermined size may be treated with the heat resistant tape 13 or the silicone rubber 14.

[0017]

EXAMPLES Each component was supplied to an extruder at a ratio shown in Table 1 and kneaded to produce pellets. A molded product was manufactured using the obtained pellets, and the characteristics were evaluated. Materials used in Examples and Comparative Examples are as follows. 1. Ethylene tetrafluoroethylene copolymer (Asahi Glass Co., Ltd., trade name "Aflon COP: C55AP") MF
R: 2 g / 10 min 2. Ethylene tetrafluoroethylene copolymer (Asahi Glass Co., Ltd., trade name "Aflon COP: C88AP") MF
R: 4 g / 10 min 3. Ethylene tetrafluoroethylene copolymer (Asahi Glass Co., Ltd., trade name "Aflon COP: C88APM") M
FR: 12 g / 10 min 4. Polyvinylidene fluoride (manufactured by Mitsubishi Petrochemical Co., Ltd., trade name "K
YNAR720]) MFR: 4 g / 10 min 5. Acetylene black (product name "Denka Black" manufactured by Denki Kagaku)

Experiments and evaluation methods in Examples and Comparative Examples are as follows. 1. Melt flow rate According to JIS K7210, temperature 300 ° C, load 2.
Measured at 16 kg. 2. Conductivity (Surface resistance: Ω / □) A surface resistance meter Hiresta HA probe (manufactured by Mitsubishi Yuka Co., Ltd.) was used for measurement at a measurement voltage of 500 V and a measurement time of 10 seconds. 3. Toner Adhesion Test A cellophane adhesive tape (JISZ152) was applied on a sample obtained by solid developing toner with the outer surface of the seamless belt facing up.
2) was sufficiently pressure-bonded, kept at about 45 degrees with respect to the surface, and peeled off at once in front, and the remaining toner amount is expressed by an area ratio. 4. Hinge characteristics According to JIS P-8115, a 150 μm-thick seamless belt is cut into a width of 10 mm and a length of 80 mm, and a hinge tester is used to perform a speed of 180 times / min, a rotation angle of 90 ° left and right, and a tensile load. The number of breaks was measured under the condition of 0.5 kg. 5. Durability A seamless belt with a width of 200 mm, both roll diameters 25φ
mm, roll speed 100 mm / sec, belt tension 8K
The condition of g / belt full width, 25 ° C., and humidity 55% was set in the apparatus of FIG. 2 and the state of cracking of the belt was visually observed.

The present invention will be further described below with reference to specific examples. (Examples 1 to 4) The composition shown in Table 1 was used to extrude below the annular die in a molten tube state using a 40φ extruder with an annular die. The extruded molten tube was attached to the outer surface of a cooling mandrel on the same axis as the annular die via a support rod and was cooled and solidified to form a seamless tube. Next, with the core installed inside the seamless tube and the roll installed outside, the seamless tube (a seamless belt cut into a predetermined length) was taken up while holding the cylindrical shape. . Table 1 shows the evaluation results of the electroconductivity, toner adhesion, hinge characteristics, and durability of the obtained belt.

Comparative Examples 1 to 3 Examples 1 to 4 except for compounding
Got a seamless belt as well. Table 1 shows the evaluations of the conductivity, toner adhesion, hinge characteristics, and durability of the obtained belt.

[0021]

[Table 1]

[0022]

As described above, according to the present invention,
It is possible to obtain a seamless belt that prevents the filming phenomenon and has excellent durability. As a result, when used in an electrophotographic copying machine or the like, there is an effect that a clear image can be obtained for a long period of time.

[Brief description of drawings]

FIG. 1 is a side view of a main part of an intermediate transfer type copying machine.

FIG. 2 is a perspective view of a seamless belt whose end face is reinforced.

[Explanation of symbols]

 1 Photosensitive Drum 2 Charging Device 3 Exposure Optical System 4 Developing Device 5 Cleaner 6 Conductive Seamless Belt 6a Inner Side 6b Outer Side 7 Conveying Roller 8 Conveying Roller 9 Conveying Roller 10 Electrostatic Transfer Device 11 Recording Paper 12 Pressing Roller 13 Reinforcing Tape 14 guide

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location C08L 27/18 KJF 9166-4J B29K 27:12 (72) Inventor Hideto Shimizu Amami Inashiki-gun, Ibaraki Prefecture 8-3-1 Machichuo, Tsukuba Research Institute, Mitsubishi Petrochemical Co., Ltd. (72) Inventor Toshihiko Tanimoto 8-3-1, Chuo, Ami-cho, Inashiki-gun, Ibaraki Mitsubishi Petrochemical Co., Ltd.

Claims (1)

[Claims] 1. A melt flow rate of 8 g / 10 mi.
Ethylene tetrafluoroethylene copolymer having an n of less than 97
.About.75% by weight and carbon black 3 to 25% by weight, and the surface conductivity of the front surface and the back surface is 1 × 10 ⁰ to 1 × 1.
Seamless belt with 0 ¹³ Ω / □.