JPH06130830A - Seamless belt and its production - Google Patents

Abstract

PURPOSE:To provide the seamless belt which has a multilayered structure, is used for an electrophotographic copying machine, etc., is hardly elongated by tension load and has the excellent durability of the boundary between the layers and its production. CONSTITUTION:This seamless belt has a two-layered structure and is formed by using the dielectric substance of a thermoplastic resin having >=800kg/cm<2> modulus in tension for the outer layer and the conductor consisting of the same thermoplastic resin as the thermoplastic resin used for the outer layer as a base for the inner later. This process for production of the seamless belt consists in simultaneously melt extruding the inner layer and the outer layer.

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 in electrophotographic copying machines, laser printers and the like, and more particularly to a seamless belt which is difficult to stretch and has good durability.

[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 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 seamless belt 6 is composed of conveying rollers 7,
It is constructed so that it is bridged over 8 and 9 and moves 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 or the like (not shown) by the optical system 3 is transferred to the photosensitive drum 1.
Form on top. The electrostatic latent image is developed into a toner image by the developing device 4. This toner image is electrostatically transferred onto the seamless belt 6 by the electrostatic transfer device 10, and the conveying roller 9 and the pressing roller 1
Transfer to the recording paper 11 between the two. In the case of a full-color electrophotographic copying machine, four color images are superposed on a seamless belt and then transferred to the recording paper 11.

When a dielectric material is used for such a seamless belt, the surface potential on the belt gradually rises due to repeated charging and discharging. Therefore, it is necessary to use a large capacity power supply. Further, it is difficult to uniformly remove the electric charges, which is a cause of uneven transfer. On the other hand, when the seamless belt has conductivity, there is a problem in that the surface potential required on the belt cannot be obtained.

In order to solve such a problem, for example, as disclosed in Japanese Patent Application Laid-Open No. 53-87738, there has been proposed a structure in which a dielectric is laminated on a base of a conductor.
In this conventional example, a conductive rubber, which is easily shaped, is used as a base, and the outer surface of the base is coated with a dielectric by a spray method or a dipping method. Further, Japanese Patent Application Laid-Open No. 62-216678 discloses a method of laminating a dielectric on a conductive rubber belt using an adhesive, and Japanese Patent Application Laid-Open No. 62-156682 describes a conductive layer made of a thermoplastic elastomer. Blow molding in which a dielectric layer made of a thermoplastic resin is simultaneously extruded is disclosed.

[0006]

However, when a conductive rubber belt or a thermoplastic elastomer is used as the conductive substrate, the belt is easily stretched by a tension load. for that reason,
When it is used in the above-mentioned copying machine, there is a problem that an image is deformed, and in the case of a full-color copying machine, color misregistration occurs. Furthermore, when the dielectric layers are laminated by dipping or an adhesive, the manufacturing process is complicated, and the durability of the interface between the conductive substrate and the dielectric is low.

[0007]

The object of the present invention is to be used in a photoconductor device such as an electrophotographic copying machine and a laser printer, a full color intermediate transfer device, a transfer separation device, a transfer device, a charging device, a developing device and the like. A seamless belt that does not easily stretch due to a tension load and has excellent durability.

That is, according to the present invention, the outer layer is a thermoplastic resin dielectric layer having a tensile elastic modulus of 8000 kg / cm ² or more, and the inner layer is a conductor layer made of the same thermoplastic resin as the outer layer. And a method for producing a seamless belt in which the outer layer and the inner layer are melt-extruded at the same time. Hereinafter, the present invention will be specifically described.

(1) Thermoplastic Resin The thermoplastic resin usable in the present invention is polypropylene,
Polyethylene, propylene ethylene block or random copolymer, styrene / butadiene, styrene / butadiene / styrene block copolymer or its hydrogenated derivative, polybutadiene, polyisobutylene, polyamide, polyacetal (POM), polyarylate, polycarbonate (PC) , Polyphenylene ether (P
PE), polyethylene terephthalate (PET), polysulfone, polyether sulfone, polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), polyether ether ketone (PEE)
K), polyvinylidene fluoride (PVDF), ethylene tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), Polyvinyl fluoride, acryl, alkyl acrylate copolymer, polyether ester copolymer, polyetheramide copolymer, polyurethane copolymer, etc., especially P
C, PET, PBT, PVDF, ETFE, PFA, F
EP is preferred. In the present invention, one of these thermoplastic resins or a mixture thereof can be used.

The melt flow rate (MFR) of these thermoplastic resins is 0.01 g / 10 min or more and 15 g /
It is preferably 10 min or less, more preferably 0.1 g / 10 min or more and 8 g / 10 min or less. MFR is 0.
If it is less than 01 g / 10 min, uniform melt extrusion becomes difficult. On the other hand, if it exceeds 15 g / 10 min, melt extrusion characteristics and crack resistance deteriorate.

Here, it is important that the derivative and the conductor are the same thermoplastic resin. However, when the thermoplastic resin is a mixture, the mixing ratio does not necessarily have to be the same as long as the interfacial strength after molding is sufficient.

(2) Thermoplastic resin conductor The thermoplastic resin conductor used in the present invention can be obtained by mixing the thermoplastic resin with a conductor filler. As the conductive filler, carbon black is preferable,
In particular, acetylene black, furnace black and channel black are preferable.

Mixing of thermoplastic resin and carbon black
The ratio is 97 to 75% by weight of thermoplastic resin and carbon
Black is 3 to 25% by weight. Carbon black 3
If it is less than 25% by weight, the conductivity is poor, and if it exceeds 25% by weight.
The material strength decreases and the appearance deteriorates. Surface conductivity
Is 10⁰-10¹³The range of Ω / □ is preferable. further,
10 when used in a seamless belt for a photoreceptor substrate⁰
-10^FiveΩ / □ is preferable. For intermediate transfer and transportation
When used as a seamless belt for fixing, fixing and developing
Is 10 ^Five-10¹³The range of Ω / □ is preferable.

Further, in the seamless belt of the present invention, additional components can be blended within a range that does not impair the effect. Such additional components include various fillers and additives. Examples of the filler include calcium carbonate (heavy, light, and colloidal), talc, mica, silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, zinc oxide, zeolite, wollastonite, diatomaceous earth, 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 oxides, organometallic compounds, and organometallic salts. As additives, antioxidants (phenolic, sulfur-based, etc.), lubricants, various organic / inorganic pigments, ultraviolet absorbers, antistatic agents, dispersants, neutralizing agents, foaming agents, plasticizers, Copper damage inhibitors, flame retardants, cross-linking agents, flow improvers and the like can be mentioned.

The thermoplastic resin conductor used in the present invention may optionally contain the above-mentioned additional components in a single-screw extruder, a twin-screw extruder,
It can be produced using a usual kneader such as a Banbury mixer, roll, Brabender, plastograph, kneader. Usually, each component is kneaded with an extruder or the like to form a pelletized 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.

(3) Method for manufacturing seamless belt The seamless belt of the present invention is formed by a method in which an outer layer and an inner layer are laminated in a molten state in a die, and melt extrusion is performed simultaneously from the die. Examples of such a method include an extrusion molding method, an injection molding method, a blow molding method, and an inflation molding method. Among these, a preferable manufacturing method is an extrusion molding method in which continuous melt extrusion is performed. Since the injection molding method and the blow molding method are discontinuous intermittent molding methods, the belt produced by these methods has a non-uniform melt orientation state in the longitudinal direction orthogonal to the circumferential direction, which in turn leads to non-uniform conductivity. There's a problem.

Of the continuous melt extrusion molding methods, the vacuum sizing method of the downward extrusion method, which can control the inner diameter of the extruded tube with high accuracy, is preferable, and the internal cooling mandrel method is most preferable. The extruded seamless belt must satisfy required properties such as conductivity, thickness uniformity, and mechanical strength in an unstretched state. This is because the stretching operation is expected to improve the mechanical strength, but causes problems such as impairing the uniformity of electrical conductivity and cracking in the stretching direction, which also impairs crack resistance. Further, the stretching causes peeling at the interface between the carbon black and the plastic, which causes the carbon to fall off and 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. Moreover, the withstand voltage is insufficient, and it becomes impossible to apply a voltage sufficient to apply the charges necessary for transfer. On the other hand, 1000μ
If it exceeds m, it becomes difficult to flexibly deform, so that it is impossible to drive at a constant speed by a small-diameter roll, and an image transfer deviation occurs. In addition, 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 makes the power supply device more expensive and larger, but also discharges between peripheral device parts. The problem of occurs.

The thickness ratio of the outer layer to the inner layer is defined as
Inner layer = 1/1 to 1/20, preferably 1/2 to 1/10. If the outer layer is thicker than this ratio, it becomes difficult to eliminate the charge, and if it is thin, the toner tends to scatter and the image deteriorates. The tensile elastic modulus of the laminated seamless belt is 8000 kg / cm ² or more, preferably 10
It is 000 Kg / cm ² or more. Tensile elastic modulus is 8000
If it is less than Kg / cm ^2, image blurring and unevenness occur due to belt elongation.

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.

[0021]

EXAMPLES The present invention will be further described below with reference to specific examples. (Example 1) 100% PVDF (Kener 720) manufactured by Penwort with MFR of 2 g / 10 min (230 ° C.)
14 parts by weight of acetylene black (Denka Black, manufactured by Denki Kagaku Co., Ltd.) having a specific surface area of 70 m ² / g was kneaded and granulated at 220 ° C. using a twin-screw extruder with a vent to make a conductive PVDF resin. Got

Next, the MFR is 2 g / 10 min (230
(° C) PVDF (Kener 720, manufactured by Pennwalt)
To form an outer layer as a dielectric, and a mixed granulated conductive PVDF resin as a conductor to form an inner layer,
Extruded at 200 ℃ from each 40mmφ extruder,
It was introduced into a two-layer coextrusion annular die at 210 ° C. and 140 mmφ and extruded from below in the state of a molten tube. This melting tube was brought into contact with the outer surface of a cooling mandrel of 130 mmφ mounted on the same axis of the annular die via an indicator rod to be cooled and solidified to obtain a seamless tube. Next, by the core located inside the seamless tube and the roll located outside, the outer layer / inner layer = 30/120 μm
It was adjusted to a seamless tube (total thickness 150 μm), and it was taken out without making a crease while maintaining the cylindrical shape.
This seamless tube was cut into a predetermined length to obtain a seamless belt. Table 1 shows the evaluation results of the thickness of the obtained belt, the conductivity of the inner layer, the conductivity distribution, the durability, and the image shift.

(Example 2) MFR is 5 g / 10 min.
(280 ° C.) PC (Mitsubishi Gas Chemical Co., Inc .: Iupilon E-2000) 83 parts by weight, MFR 4 g / 10 mi
17 parts by weight of n (230 ° C.) PBT (Novadol 5020 manufactured by Mitsubishi Kasei Co., Ltd.) was kneaded and granulated at 270 ° C. using a twin-screw extruder with a vent to obtain a PC resin as a derivative.

Next, the MFR is 5 g / 10 min (280
℃) PC (Mitsubishi Gas Chemical Co., Ltd .: Iupilon E-2)
000) 83 parts by weight, MFR 4 g / 10 min (23
0 ° C PBT (Mitsubishi Kasei Co., Ltd .: Novador 502)
0) 17 parts by weight, and acetylene black having a specific surface area of 70 m ² / g (DENKA BLACK manufactured by Denki Kagaku KK) 1
4 parts by weight were kneaded and granulated at 270 ° C. using a twin-screw extruder with a vent to obtain a conductive PC resin as a conductor.
Using the obtained dielectric resin and conductive resin, a seamless tube was obtained under the same conditions as in Example 1 except that the extrusion temperature was changed to 280 ° C. Table 1 shows the evaluation results of the thickness of the obtained belt, the conductivity of the inner layer, the conductivity distribution, the durability, and the image shift.

(Example 3) MFR was 2 g / 10 min.
(300 ℃) ETFE (Asahi Glass Co., Ltd .: Aflon C)
OP C55AP) 100 parts by weight specific surface area 70 m ² /
16 parts by weight of acetylene black (Denka Black, manufactured by Denki Kagaku Co., Ltd.) of 2 g was
The conductive ETFE resin was obtained by kneading and granulating at 80 ° C.

ETFE (Asaron Glass Co., Ltd .: Aflon COP C55A) with MFR of 2 g / 10 min (300 ° C.)
A seamless tube was obtained under the same conditions as in Example 1 except that P) was used as a dielectric and the extrusion temperature was changed to 290 ° C. Table 1 shows the evaluation results of the thickness of the obtained belt, the conductivity of the inner layer, the conductivity distribution, the durability, and the image shift.

Comparative Example 1 The PVDF used as the dielectric in Example 1 was used as the dielectric, and the PC resin used as the conductor in Example 2 was used as the conductor, and the extrusion temperatures were 200 ° C. and 280, respectively. ℃, the temperature of the annular die 280
A seamless belt was obtained in the same manner as in Example 1 except that the temperature was changed to ° C. The thickness of the obtained belt, the conductivity of the inner layer,
Table 1 shows the evaluation results of the conductivity distribution, durability and image shift.

(Comparative Example 2) The conductive ETFE resin used as the conductor in Example 3 was fed from an extruder of 40 mmφ to 29
At 0 ° C., it was introduced into a single-layer annular die of 140 mmφ, 290 ° C. and extruded from below the annular die in a molten tube state. This melting tube was processed in the same manner as in Example 1 to obtain 130 μm.
A m-thick, single-layer seamless tube was obtained.

On the outer surface of the obtained seamless tube,
100 parts of a fluororesin (manufactured by Asahi Glass Co., Ltd .: Lumiflon LF200C) as a dielectric and a curing agent (manufactured by Asahi Glass Co., Ltd .:
Isocyanate-based Lumiflon LF200C curing agent) 1
A mixed solution obtained by mixing and stirring 00 parts and 200 parts of xylene was applied and dried at 80 ° C. for 1 hour to obtain an outer layer (coating film) having a thickness of 20 μm. Table 1 shows the evaluation results of the thickness of the obtained belt, the conductivity of the inner layer, the conductivity distribution, the durability, and the image shift.

(Comparative Example 3) MFR is 3 g / 10 min.
(230 ° C.) polyolefin elastomer (manufactured by Mitsubishi Petrochemical Co., Ltd .: SPX8600) was used as a dielectric, and MFR was 3
Vent 16 parts by weight of acetylene black (Denka Black, manufactured by Denki Kagaku Co., Ltd.) having a specific surface area of 70 m ² / g to 100 parts by weight of a polyolefin elastomer (SPX8600, manufactured by Mitsubishi Petrochemical Co., Ltd.) of g / 10 min (230 ° C.). The mixture was kneaded and granulated at 220 ° C. by using a twin-screw extruder attached thereto to obtain a conductive polyolefin olefin resin as a conductor. Using these resins, a seamless tube was obtained under the same conditions as in Example 1 except that the extrusion temperature was changed to 200 ° C. The evaluation results of the obtained belt thickness, inner layer conductivity, conductivity distribution, durability and image shift are shown in Table 1.
Shown in.

Measurements in Examples and Comparative Examples,
The evaluation was performed as follows. 1. MFR Based on Japanese Industrial Standard (JIS) K7210, it was measured with a load of 2.16 Kg. 2. Conductivity (Surface resistance: Ω / □) Surface resistance meter Hiresta HT probe (Mitsubishi Yuka Co., Ltd.)
(Manufactured by Mfg. Co., Ltd.) was used at a measurement voltage of 500 V and a measurement time of 10 seconds. 3. Tensile modulus was measured by a method in accordance with International Standardization Organization (ISO) standard R1184.

4. Durability A seamless belt with a width of 200 mm and a roll diameter of 25 m
mφ, roll speed 100 mm / sec, belt tension 8K
It was set in the apparatus of FIG. 2 under the conditions of g / 200 mm, 25 ° C., and humidity of 55%, and the peeling state of the interface between the dielectric layer and the conductor layer was visually observed. A belt in which peeling was not recognized for 1000 hours or more was judged as ◯, and a belt in which peeling was recognized for 100 hours or less was judged as x. 5. Image shift In the apparatus shown in FIG. 1, the belt tension is 10 Kg / 20.
When the image shift between 0 mm and 12 kg / 200 mm was 0.1 mm or less, it was judged as ◯, and when 0.2 mm or more was judged as ×.

[0033]

[Table 1]

[0034]

As described above, according to the present invention,
A high tensile elastic modulus and a high tensile elastic modulus can be obtained by using a thermoplastic resin dielectric having a tensile elastic modulus of 8000 kg / cm ² or more as the outer layer and a conductor layer made of the same thermoplastic resin as the outer layer in the inner layer. A seamless belt with both durability can be obtained.

[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 Codes] 1 Photosensitive drum 2 Charging device 3 Exposure optical system 4 Developing device 5 Cleaner 6 Seamless belt 6a Inner side surface 6b Outer side surface 7 Conveying roller 8 Conveying roller 9 Conveying roller 10 Electrostatic transfer device 11 Recording paper 12 Pressing roller 13 Reinforcing tape 14 Guide

Claims (2)

[Claims] 1. The outer layer has a tensile elastic modulus of 8,000 Kg / c.
A seamless belt comprising a thermoplastic resin dielectric layer of m ² or more, the inner layer of which is composed of a conductor layer of the same thermoplastic resin as the outer layer. 2. The method for producing a seamless belt according to claim 1, wherein the outer layer and the inner layer are melt-extruded at the same time.