JPH06228335A - Seamless belt - Google Patents

Abstract

PURPOSE:To provide a seamless belt having high flame retardancy, high durability and difficult extensibility and used in a photosensitive device such as an electrophotographic copier or a laser printer, a full-color intermediate image transfer machine, a transfer/separation device, a carrying device, a charging device, a developing machine, etc. CONSTITUTION:The belt is made from 97-75wt.% resin composition mainly consisting of polyvinylidene fluoride having a tensile modulus of 10000kg/cm<2> or above and a melt flow rate of 10g/10min or below and 3-25wt.% carbon black, and has a surface conductivity of 1X10<0> to 1X10<13>OMEGA/cm<2> on its face and back.

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 in an intermediate transfer device such as an electrophotographic copying machine and a laser printer, a transfer separation device, a conveying device, a charging device, a developing device, and the like. The present invention relates to a seamless belt that has high flame retardancy, high durability, and is resistant to deformation.

[0002]

2. Description of the Related Art Conventionally, endless belts have been widely used in intermediate transfer devices, transfer separation devices, conveying devices, charging devices, developing devices, etc., such as 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 endless belt. 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 around the photosensitive drum 1. Are arranged. The conductive endless belt 6 is stretched around the conveying rollers 7, 8 and 9 and moves in the arrow direction in synchronization with the photosensitive drum rotating in the arrow direction.

Next, the operation will be described. 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 on it by the optical system 4, and this latent image is developed by a developing device. The toner image formed by this development is electrostatically transferred to the conductive endless belt 6 by the electrostatic transfer device 10. The toner image transferred onto the belt is conveyed by the conveying rollers 7, 8 and 9, and the recording paper 1 is conveyed between the conveying roller 9 and the pressing roller 12.
Transferred to 1.

[0004]

Such a seamless belt is required to be flame-retardant because it is used in the apparatus for a long time near a high temperature component or in a high temperature atmosphere. Specifically, flame retardancy according to the UL standard of the United States, which is well known as a measure of flame retardancy of electric devices and plastic materials, is required.

Further, since it is functionally used for a long time under high tension by using two or more rolls, it must have sufficient strength and durability. Further, in the case of a belt used for an intermediate transfer device or the like, it is necessary to prevent the belt from stretching because stretching of the belt causes image misalignment. Further, it is important that the toner does not stick to the surface of the belt, because if the toner sticks to the surface of the belt, the sharpness of the image is impaired.

The conventional conductive seamless belt made of a thermoplastic resin uses a material obtained by adding a combustible conductive particle such as carbon black to a thermoplastic resin, and thus the flame resistance of the belt is low. Therefore, attempts have been made to improve flame retardancy by adding various flame retardants, conductive seamless belt made of resin with flame retardant added, compared to conductive seamless belt without flame retardant added, It has been found that cracks are likely to occur when the belt is driven and durability is poor.

On the other hand, it has been practiced to use a fluororesin having a high flame retardance, but since the elastic modulus of the fluororesin is low, there is a problem that the belt is stretched and deformed when the belt is driven and the image is displaced. have.

[0008]

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. Among the seamless belts to be used, it is to provide a seamless belt that has high flame retardancy, rich durability, and is difficult to stretch.

Therefore, in the present invention, the object was achieved by selecting a specific polyvinylidene fluoride resin as the fluorine resin constituting the seamless belt. That is, the seamless belt of the present invention has a tensile elastic modulus of 10,000 Kg / cm ² or more and a melt flow
The polyvinylidene fluoride resin composition having a rate (MFR) of 10 g / 10 min or less is composed of 97 to 75% by weight and carbon black of 3 to 25% by weight, and the surface conductivity of the front and back surfaces of the seamless belt is 1 × 10 ⁰ to 1%. × 10 ¹³
Ω / □ is a seamless belt.

The present invention will be described in detail below. (1) Polyvinylidene fluoride-based resin composition The polyvinylidene fluoride-based resin composition used in the present invention has a tensile elastic modulus of 10,000 (Kg / cm ² ) or more and a melt flow rate of 10 g / 10 min or less. Then, not only a vinylidene fluoride homopolymer,
A copolymer with propylene hexafluoride, ethylene tetrafluoride, or the like, and a mixture of these polymers and another resin can be used.

Examples of resins that can be used in the mixture include acrylic resins such as polymethylmethacrylate and ethylene / acrylic acid alkyl ester copolymers, which are flammable and easily adhere to the toner. Therefore, it is desirable that the blending amount be 20% by weight or less. The preferred tensile modulus is 12000 (Kg / cm
² ) or more, particularly preferable tensile elastic modulus is 15000 (K
g / cm ² ) or more. Tensile modulus of 10000 (K
If it is less than g / cm ² ), the belt stretches and an image shift occurs when an image is transferred.

The preferred melt flow rate is 4 g /
Less than 10 min, particularly preferably 2 g / 10 min
Less than is preferred. Melt flow rate is 10g / 1
If it exceeds 0 min, the crack resistance is extremely poor and the durability is poor. These polyvinylidene fluoride resin compositions may further contain additional components such as thermoplastic resins, thermosetting resins, various fillers and additives other than the above unless the effects of the present invention are significantly impaired. . Examples of the thermoplastic resin include polypropylene, polyethylene (high density, medium density, low density, linear low density), propylene ethylene block or random copolymer, rubber or latex component such as ethylene / 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 crystalline polyester, polysulfone, polyether sulfone, polyphenylene sulfide, polybisamide triazole, polyetherimide, polyether ether ketone, polybutylene terephthalate, polyethylene terephthalate, polyfluoride Vinyl, chlorotrifluoroethylene, ethylene tetrafluoroethylene copolymer, hexafluorofluoropropylene, perfluoroalkyl vinyl ether copolymer, acrylic, acrylic acid alkyl ester copolymer, polyester ester copolymer, polyether ester copolymer Consists of one kind of a combination, a polyether amide copolymer, a polyurethane copolymer, or a mixture thereof. The are used.

As the thermosetting resin, for example, an epoxy resin, a melamine resin, a phenol resin, an unsaturated polyester resin, or a mixture thereof is used. As various fillers, for example, calcium carbonate (heavy, soft, colloidal), talc, mica, silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, zinc oxide, zeolite, wollastonite, diatomaceous earth, Glass beads, bentonite, montmorillonite, asbestos, hollow glass spheres, graphite, molybdenum disulfide, titanium oxide, aluminum fiber, stainless steel fiber, brass fiber, aluminum powder, wood powder,
Examples thereof include fillers such as rice husks, graphite, metal powder, conductive metal oxides, organic metal compounds and organic metal salts.

The additives include, for example, antioxidants (phenol type, sulfur type, etc.), lubricants, various organic / inorganic pigments, ultraviolet absorbers, antistatic agents, dispersants, neutralizing agents, foaming agents. , Plasticizers, copper damage inhibitors, cross-linking agents, flow improvers, and the like.

(2) Carbon black Preferred as the carbon black used in the present invention are acetylene black, furnace black and channel black. Among them, acetylene black having good dispersibility is particularly preferable because it does not impair the appearance of the seamless belt.

(3) Blending amount The blending amount of the polyvinylidene fluoride resin and carbon black of the present invention is such that the polyvinylidene fluoride resin is 97 to 75.
The amount of carbon black is 3 to 25% by weight, preferably 90 to 80% by weight of polyvinylidene fluoride resin. If the carbon black content is less than 3% by weight, the conductivity is poor, and if it exceeds 25% by weight, the appearance of the product is deteriorated and the material strength is lowered, which is not preferable.

(4) Conductivity The surface conductivity is preferably in the range of 10 ⁰ to 10 ¹³ Ω / □. Photoreceptor substrates for seamless belt, when used in fixing seamless belt, 10 ⁰ ~10 ⁵ Ω / □ preferably, 10 ⁰ ~10 ³ Ω / □ is particularly preferred. When used as an intermediate transfer seamless belt, a transport seamless belt, a fixing seamless belt, a developing seamless belt, etc., 10 ⁵ to 10 ¹³ / □ is preferable and 10 ⁷
-10 ¹² Ω / □ is particularly preferable.

(5) Compounding method The above composition is produced by using a conventional kneading machine such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll, a Brabender, a plastograph and a kneader, if desired, with the additional components. can do. Usually, each component is kneaded with an extruder or the like to form a pelletized compound, which is then subjected to processing, but in a special case, each component is directly supplied to a molding machine,
The composition can also be molded while kneading it with a molding machine.

(6) Seamless Belt Manufacturing Method The seamless belt manufacturing method is a continuous melt extrusion molding method,
A known method such as an injection molding method, a blow molding method, or an inflation film molding method can be adopted. The preferred manufacturing method is the continuous melt extrusion method.

As a preferable continuous melt extrusion molding method for a seamless belt, when the diameter of the belt is 30 mm or more, an inner cooling mandrel system of a downward extrusion system capable of controlling the inner diameter of the extruded tube with high accuracy, and a diameter of 30
In the case of less than mm, in addition to the internal cooling mandrel method, the vacuum sizing method can be used.

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.

(7) Seamless belt The thickness of the seamless belt is 50 μm or more and 1000 μm.
The following is preferable, and 100 μm or more and 700 μm or less is more preferable. 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. Also, 100
If it exceeds 0 μm, it becomes difficult to flexibly deform, so that it is not possible to drive at a uniform speed by a small-diameter roll, and an image transfer deviation occurs. Furthermore, since the electrostatic capacity becomes smaller, it is not possible to apply the charge required 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 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.

[0024]

【Example】

(Examples 1 to 3 and Comparative Examples 1 and 2) As shown in Table 1, each component was supplied to an extruder at a predetermined ratio and kneaded.
Pellets were produced. The obtained pellets were extruded at a temperature of 230 ° C. at
It was extruded in the form of a molten tube below a 0φ annular die. This molten tube was brought into contact with the outer surface of a cooling mandrel mounted on the same axis of an annular die via a support rod to be cooled and solidified to obtain a seamless tube having 120 mmφ and a thickness of 150 μm. Then, with the core installed inside the seamless tube and the roll installed outside, in the state where the seamless tube (cut into a predetermined length is a seamless belt) is held in the cylinder (with a crease I took it. The conductivity, tensile modulus, folding endurance, durability and image shift of the obtained belt were evaluated. The evaluation results are shown in Table 1.

(Comparative Examples 3 to 4) Seamless as in Examples 1 to 3 and Comparative Examples 1 and 2 above, except that the extrusion temperature was 280 ° C. and the molten tube was extruded below the 150φ annular die. A tube was obtained.

Materials used in Examples and Comparative Examples are
It is as follows. 1. Polyvinylidene fluoride (manufactured by Mitsubishi Petrochemical Co., Ltd., trade name "K
YNAR740 ") MFR: 0.3 g / 10 min 230 ° C 2. Polyvinylidene fluoride (manufactured by Daikin Industries, Ltd., trade name "Neotron VP820") MFR: 1g / 10min
230 ° C 3. Polyvinylidene fluoride (manufactured by Mitsubishi Petrochemical Co., Ltd., trade name "K
YNAR720 ") MFR: 4g / 10min 230 ° C 4. Polyvinylidene fluoride (manufactured by Mitsubishi Petrochemical Co., Ltd., trade name "K
YNAR710 ") MFR: 12 g / 10 min 230 ° C 5. 5. Polyvinylidene fluoride-propylene hexafluoride copolymer (manufactured by Mitsubishi Petrochemical Co., Ltd., trade name "KYNAR2812") MFR: 0.3 g / 10 min 230 ° C 6. Polycarbonate (Mitsubishi Gas Chemical Co., Ltd., trade name "Upilon E2000") MFR: 5 g / 10 min 280 ° C 7. Acetylene black (product of Denki Kagaku Co., Ltd., trade name "Denka Black") 8. Flame retardant (manufactured by Teijin Chemicals, Fireguard 700
0) Evaluation methods in Examples and Comparative Examples are as follows.

1. MFR Examples 1-3 and Comparative Examples 1-2 are JIS K-7210.
The temperature was 230 ° C. and the load was 2.16 Kg. Comparative Example 3 was measured according to JIS K-7210 at a temperature of 280 ° C. and a load of 2.16 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. Tensile Elastic Modulus According to ISO R1184, a strip-shaped test piece having a width of 15 mm and a length of 150 mm was used as the test piece, and the test piece was measured with an autograph tensile tester at a pulling speed of 1.0 mm / min and a chuck distance of 100 mm.

4. Folding endurance According to JIS P-8115, the test piece has a width of 10 m.
m, 80 mm long test piece, MIT tester speed 180 times / min, rotation angle 90 ° left and right, tensile load 0.5
The number of breaks was measured under the condition of 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., 55% was set in the apparatus of FIG. 2 and the cracked state of the belt was visually observed. 10
The one having a durability of 0 hours or more was marked with ◯.

6. Image misalignment With the device shown in Fig. 1, the tension applied to the belt is 10 kg / 200 m.
m and 12 kg / 200 mm, and the image misalignment was 0.1 mm or less as O, and 0.2 mm or more as X.

7. Flame retardance A sheet sample having a thickness of 150 μm was subjected to a combustion test according to UL-94VTM.

[0034]

As described above, according to the present invention,
By forming a seamless belt using a specific fluororesin composition, a seamless belt having high flame retardancy, excellent durability, and being difficult to stretch 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 symbols]

 1 Photosensitive Drum 2 Charging Device 3 Exposure Optical System 4 Developing Device 5 Cleaner 6 Seamless Belt 6a Inner Side 6b Outer Side 7, 8, 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 code Internal reference number FI Technical display location G03G 15/00 108 7369-2H 15/16 // B65G 15/32 7030-3F (72) Inventor Hidetoshi Shimizu 8-3-1 Chuo, Ami-cho, Inashiki-gun, Ibaraki Mitsubishi Petrochemical Co., Ltd. Tsukuba Research Institute (72) Inventor Toshihiko Tanimoto 8-3-1 Chuo, Ami-cho, Inashiki-gun, Ibaraki Mitsubishi Petrochemical Co., Ltd. Tsukuba Research Institute

Claims (1)

[Claims] 1. A tensile elastic modulus of 10,000 (Kg / c)
m ² ) or more, melt flow rate is 10 g / 10 min
The following resin composition containing polyvinylidene fluoride as a main component 97 to 75% by weight and carbon black 3 to 25% by weight
And the surface conductivity of the front and back surfaces of the seamless belt is 1 × 10 ⁰ to 1 × 10 ¹³ Ω / □.