JPH07172613A - Seamless belt - Google Patents

Abstract

PURPOSE:To provide a seamless belt for holding an excellent image for a long period. CONSTITUTION:A seamless belt is provided in such a way as consisting of a thermoplastic resin of 97 to 75% by weight and a carbon black of 3 to 25% by weight, its sheet resistivity being 1X10<8> to 1X10<12>OMEGA/square on the front and rear surfaces, and volume resistance value after applying a voltage of 0.7V/mum continuously for one hour being 10% or more of the volume resistance value after ten seconds of voltage application.

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 conductive seamless belt 6 includes the transport rollers 7, 8,
It is configured to move in the direction of arrow B in synchronism with the photosensitive drum which is stretched around 9 and rotates in the direction of arrow A.

Next, the operation will be described. First arrow A
The surface of the photosensitive drum 1 rotating in the direction 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 to the conductive seamless belt 6 by the electrostatic transfer device 10, and the transfer roller 9
The image is transferred to the recording paper 11 between the pressure roller 12 and the pressure 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]

Conventionally, in these seamless belts, research has been conducted with a focus on high durability and prevention of toner sticking. On the other hand, an intermediate transfer type copying machine using a seamless belt has a problem that the image quality deteriorates with time, and a countermeasure against it has been required.

[0006]

The present inventors have found that it is possible to retain an excellent image for a long period of time by using a seamless belt that satisfies certain conditions, and have completed the present invention. That is, according to the present invention, the thermoplastic resin is composed of 97 to 75% by weight and carbon black is 3 to 25% by weight, and the surface resistance of the front surface and the back surface is 1 × 10 ⁸ to.
A seamless belt having a volume resistance value of 1 × 10 ¹² Ω / □ and a volume resistance value after continuously applying a voltage of 0.7 V / μm for 1 hour is 10% or more of the volume resistance value 10 seconds after the application is used. As a result, deterioration of image quality over time can be suppressed.

The present invention will be specifically described below. (1) Thermoplastic resin The thermoplastic resin used in the present invention refers to a thermoplastic resin that can be easily obtained on the market. For example, polypropylene, polyethylene (high density, medium density, low density, linear), 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, liquid crystalline polyester, polyethylene terephthalate, polysulfone, polyether sulfone, polyphenylene sulfide, polybisamide triazole, polybutylene terephthalate, polyetherimide, poly Ether ether ketone, acrylic,
Ethylene / tetrafluoroethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, chlorotrifluoroethylene, hexafluoropropylene / perfluoroalkyl vinyl ether copolymer, acrylic acid alkyl ester copolymer, polyester ester copolymer, polyether It is possible to use one or a mixture of ester copolymer, polyetheramide copolymer, polyurethane copolymer and the like.

(2) Carbon Black As the carbon black used in the present invention, acetylene black, furnace black and channel black are preferable. Among these, acetylene black is particularly preferable in order to prevent appearance defects due to aggregation of carbon and the like. (3) Compounding amount: 97-75 wt% of thermoplastic resin and 3-carbon black
25 wt% Carbon black less than 3 wt% has poor conductivity,
If it exceeds 25%, problems such as deterioration of appearance of the product and reduction of strength occur.

(4) Surface Resistance The surface resistance is preferably 1 × 10 ⁸ to 1 × 10 ¹² Ω / □ when used for intermediate transfer, transportation, fixing, development, etc., and 1 × 10. ⁹ to 1 × 10 ¹⁰ Ω / □ is particularly preferable. If it is lower than 1 × 10 ⁸ Ω / □, the voltage leaks and causes an image defect. If it is higher than 1 × 10 ¹² Ω / □, the voltage at the time of transfer needs to be increased, which causes considerable damage to the belt. This shortens the life of the belt.

(5) Permissible Range of Change in Volume Resistance Value In order to suppress deterioration of the transferred image with time, it is necessary that the volume specific resistance value of the seamless belt be within a certain range. Specifically, the volume resistance value after continuously applying a voltage of 0.7 V / μm for 1 hour must be 10% or more of the volume resistance value 10 seconds after the application. If it is less than 10%, it becomes a factor causing image defects.

(6) Additive Components Furthermore, in the present invention, additional components may be added in addition to these components as long as the effects of the invention are not significantly impaired. As additional components, various fillers such as calcium carbonate (heavy, light, and colloidal) talc, mica, silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, zinc oxide, zeolite, wollastonite, and 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,
In addition to fillers such as metal powder, conductive metal oxides, organic metal compounds, organic metal salts, etc., as additives: antioxidants (phenol-based, sulfur-based, etc.), lubricants, various organic / inorganic pigments, ultraviolet rays Examples thereof include an absorbent, an antistatic agent, a dispersant, a neutralizing agent, a foaming agent, 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 Materials used in Examples and Comparative Examples are as follows. 1. Polypropylene (trade name "Mitsubishi Polypro: FY6" manufactured by Mitsubishi Petrochemical Co., Ltd.) 2. Ethylene tetrafluoroethylene copolymer (Asahi Glass Co., Ltd., trade name "Aflon COP: C55AP") 3. Polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Inc., trade name "Upilon: E-2000", MFR 4g / 10min,
280 ° C) 4. Polybutylene terephthalate (manufactured by Mitsubishi Kasei, trade name "Novadol: 5020", MFR 14g / 10mi
n, 230 ° C.) 5. Acetylene black (product name "Denka Black" manufactured by Denki Kagaku)

Experiments and evaluation methods in Examples and Comparative Examples are as follows. 1. Surface resistance: Ω / □ A surface resistance meter Hiresta HA probe (manufactured by Mitsubishi Petrochemical Co., Ltd.) was used to measure a sample having a thickness of 150 μ at a measurement voltage of 500 V and a measurement time of 10 seconds. 2. Volume resistance: Ω · cm Using RA8340A manufactured by Advantest Corporation JIS K-
In accordance with 6911, measurement was performed using a sample having a thickness of 150 μm. The applied voltage was 100 V / 150 μm. However, the electrode is made of conductive silicone rubber, and the force for pressing the electrode against the sample is 4 kg.

3. Time characteristics The voltage is continuously applied during the measurement of volume resistance, the volume resistance after 1 hour is measured, and the volume resistance retention rate is calculated by comparing with the volume resistance after 10 seconds. That is, the resistance retention rate (%) = (volume resistance value after 1 hour / 10 volume resistance value after 10 seconds) × 100. 4. Image test A seamless belt was attached to the apparatus shown in FIG. 1 and 1000 A4 size sheets were copied, and the state of the image was observed. The image was observed with the naked eye, and when a white portion (not transferred) was observed, it was evaluated as ×, and when not, it was evaluated as ○.

The present invention will be further described below with reference to specific examples. (Example 1) Each component was supplied to the extruder at the ratio shown in Table 1 and kneaded at a kneading temperature of 220 ° C and a discharge rate of 40 kg / h to produce pellets. The obtained pellets are extruded below the annular die in a molten tube state using a 40φ extruder with an annular die. The extruded melting tube was mounted on the same axis as the annular die via a support rod,
The seamless tube was made by contacting the outer surface of the cooling mandrel and solidifying by cooling. 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 surface resistance, volume resistance, time characteristics, and evaluation results of the image test of the obtained belt.

(Examples 2 to 5) A seamless belt was obtained in the same manner as in Example 1 except that the components were supplied to the extruder at the proportions shown in Table 1 and the kneading temperature was 280 ° C. Table 1 shows the surface resistance, volume resistance, time characteristics, and evaluation results of the image test of the obtained belt.

(Comparative Examples 1 and 2) Examples 2 to 5 except for compounding
Got a seamless belt as well. Table 1 shows the surface resistance, volume resistance, time characteristics, and evaluation results of the image test of the obtained belt.

(Comparative Example 3) A seamless belt was obtained in the same manner as in Examples 2 to 5, except that the kneading temperature was changed to 310 ° C and the discharge rate was changed to 80 kg / h in the step of pelletizing the pellets. Table 1 shows the surface resistance, volume resistance, time characteristics, and evaluation results of the image test of the obtained belt.

[0024]

[Table 1]

[0025]

As described above, according to the present invention,
By using a seamless belt in which the decrease of the volume resistivity value under a predetermined condition is within a certain range, it is possible to suppress deterioration of image quality over 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 7 Conveying Roller 8 Conveying Roller 9 Conveying Roller 10 Electrostatic Transfer Device 11 Recording Paper 12 Pressing Roller 13 Heat Resisting Tape 14 Silicon Rubber

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI technical display location G03G 15/16 // B65G 15/32 (72) Inventor Chiharu Kongou 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Petrochemical Co., Ltd. Yokkaichi Research Institute (72) Inventor Hideto Shimizu 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Petrochemical Co., Ltd. Yokkaichi Operations

Claims (1)

[Claims] 1. A thermoplastic resin of 97 to 75% by weight and carbon black of 3 to 25% by weight, and the surface resistance of the front and back surfaces is 1 × 10 ⁸ to 1 × 10 ¹² Ω / □, and
A seamless belt, wherein the volume resistance value after continuously applying a voltage of 0.7 V / μm for 1 hour is 10% or more of the volume resistance value 10 seconds after the application.