JPH0695517A - Seamless belt - Google Patents

Abstract

PURPOSE:To prevent the filming phenomenon of a toner and to prevent the toner from sliding against a roller by dropping water on an outside surface serving as a test piece, and setting the angle of contact between the test piece plane and the water droplet to a specific value or more, and setting the coefficient of kinetic friction of its inside surface to a specific value ore more. CONSTITUTION:The wettability of a seamless belt is measured with the angle of contact between a test piece plane and water as a measure. When a water droplet is placed on the surface of a test piece, the surface tension of the test piece, the interfacial tension of the liquid/test piece, and the surface tension of the liquid balance one another so that the water droplet takes a fixed form. When water is dropped on the outside surface of the seamless belt serving as a test piece, the angle of contact between the test piece plane and the water droplet is 90 deg. or more and the coefficient of kinetic friction of its inner surface is 0.25 or more at measurement specified by ASTM D1894-73. When the angle of contact between the test piece plane and the water droplet is less than 90 deg., the effect of improvement of a filming phenomenon is so small that a toner remains. The surface conductivity of the outside and inside surfaces is preferably in the range 1X10 deg. is 1X10<13>OMEGA/sq. unit.

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 having improved toner removing properties and roll resistance.

[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]

A seamless belt used in an electrophotographic copying machine is required to have smoothness for obtaining a clear image. 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 the compatibility and slipperiness of the surface may affect it. In fact, the filming phenomenon is improved by improving the slipperiness of the belt. However, it was found that when the slipperiness was improved, slippage with the conveying roller occurred, and image unevenness occurred and a clear image could not be obtained.

[0006]

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. Another object of the present invention is to provide a conductive seamless belt that prevents the filming phenomenon of toner and also prevents the roller from slipping.

As a result of earnest studies to achieve this object, it was found that the filming phenomenon is deeply related to the wettability of the belt with water. Based on this finding, we have realized a seamless belt that prevents filming phenomenon and slippage between rollers. That is, in the conductive seamless belt according to the present invention, when water is dropped on the outer surface of the test piece as a test piece, the contact angle between the test piece flat surface and the water drop is 90 ° or more, and the dynamic friction resistance of the inner surface is ASTM D1894-.
The seamless belt is 0.250 or more as measured by 73. Alternatively, in the seamless belt, the surface conductivity of the front surface and the back surface is 1 × 10 ⁰ to 1 × 1.
It is a seamless belt characterized in that it is 0 ¹³ Ω / □.

The present invention will be specifically described below. (1) Wettability of seamless belt The wettability referred to here is measured using the contact angle between the plane of the test piece and water as a scale. When water droplets are placed on the surface of the test piece, the surface tension of the test piece, the interfacial tension of the liquid / test piece, and the surface tension of the liquid are balanced to form a certain shape. At that time, if the droplet is small and the influence of gravity can be ignored, the following equation (Young's equation) is established.

RSV-rSL = rLVCosθ where rSV: surface tension of test piece rSL: interfacial tension of test piece in liquid rLV: surface tension of liquid θ: contact angle The contact angle of the surface of the seamless belt of the present invention is 90 °. Or more, preferably 95 ° or more. When the contact angle is less than 90 °, the effect of improving the filming phenomenon is small and the toner remains.

(2) State of Inner Surface of Seamless Belt The friction coefficient of the inner surface of the seamless belt of the present invention is AS
The dynamic friction resistance coefficient according to TM D1894-73 (aluminum foil is used for the counterpart) is 0.250 or more, preferably 0.300 or more, and more preferably 0.35.
It is 0 or more. When the dynamic frictional resistance does not reach the above value due to the performance of the resin composition itself, the above dynamic frictional resistance can be obtained by roughening the inner surface in-line during the production of the seamless belt. For example, in the internal cooling mandrel system, the surface of the internal cooling mandrel may be roughened. Further, it is also possible to obtain the above-mentioned dynamic friction resistance by roughening the inner surface with, for example, an Sumitomo 3M imperial wrapping film after the seamless belt is manufactured. In this case, it is desirable that the lapping film use a mesh of # 3000 or less.

(3) Material The material of the seamless belt of the present invention is basically composed of a resin composition comprising a thermoplastic resin and a conductive filler.

The thermoplastic resin used in the present invention includes polypropylene, polyethylene (high density, medium density,
Low density, linear low density), propylene ethylene block or random copolymer, rubber or latex component,
For example, ethylene / propylene copolymer rubber, styrene /
Butadiene rubber, styrene-butadiene-styrene block copolymer or its hydrogenated derivative, polybutadiene, polyisobutylene, polyamide, polyamideimide, polyacetal, polyarylate, polycarbonate, polyphenylene ether, modified polyphenylene ether, polyimide, liquid crystalline polyester, polyethylene Terephthalate, polysulfone, polyethersulfone, polyphenylene sulfide, polybisamide triazole, polybutylene terephthalate, polyetherimide, polyether ether ketone, acrylic, polyvinylidene fluoride, polyvinyl fluoride, ethylene tetrafluoroethylene copolymer, chlorotrifluoro Ethylene copolymer, hexafluoropropylene, perfluoroalkyl vinyl ether One or a mixture of a tercopolymer, an acryl, an acrylic acid alkyl ester copolymer, a polyester ester copolymer, a polyether ester copolymer, a polyetheramide copolymer, a polyurethane copolymer, and the like. Is used.

The conductive filler is at least one selected from carbon black, graphite, carbon fibers, metal powder, conductive metal oxides, organic metal compounds, organic metal salts, conductive polymers, etc., or a mixture thereof. Those consisting of are preferred. Among them, carbon black is particularly preferable. Preferred carbon blacks include acetylene black, furnace black and channel black.

The blending amount is 3 to 25 parts by weight with respect to 100 parts by weight of the thermoplastic resin. When the conductive filler is less than the above range, the conductivity is poor, and when it exceeds the above range, the appearance of the product is deteriorated and the material strength is lowered, which is not preferable.

The surface conductivity is preferably in the range of 10 ⁰ to 10 ¹³ Ω / □. When used as a photoreceptor substrate,
10 ⁰ to 10 ⁵ Ω / □ is preferable, and 10 ⁰ to 10 ³ Ω /
□ is particularly preferable. 10 ⁵ to 10 ¹³ Ω / □ when used for intermediate transfer, transportation, fixing, development, etc.
Is preferable, and 10 ⁷ to 10 ¹² Ω / □ is particularly preferable.

Further, in the present invention, additional components can be blended in addition to these components within a range that does not significantly impair the effects of the invention. As the additional component, various fillers, for example, calcium carbonate (heavy, light, 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,
In addition to fillers such as aluminum fibers, stainless steel fibers, brass fibers, aluminum powder, wood powder, chaff, thermosetting resins such as epoxy resins, melamine resins, phenol resins, unsaturated polyester resins: antioxidants (phenolic materials) , Sulfur, etc.), lubricants, various organic / inorganic pigments, ultraviolet absorbers, antistatic agents, dispersants, neutralizing agents, foaming agents, plasticizers, copper damage inhibitors, flame retardants, cross-linking agents, flowability Examples thereof include improvers.

In the thermoplastic resin composition, if desired, additional components may be added to a single screw extruder, a twin screw extruder, a Banbury mixer,
It can be produced by using an ordinary kneader such as a roll, a brabender, a plastograph, and a kneader. Normally,
Each component is kneaded with an extruder or the like to form a pelletized compound, which is then processed.However, in special cases, each component is directly supplied to the molding machine and the composition is kneaded while molding with the molding machine. You can also

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 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 most preferable.

In the internal cooling mandrel system, since the diameter of the seamless belt is regulated while pressing the inner surface of the seamless belt against the surface of the cooling mandrel, the friction resistance can be increased by roughening the surface of the cooling mandrel. The vacuum sizing method is a method of pressing the outer surface of the seamless belt against the vacuum sizing surface to control the diameter of the seamless belt. Therefore, in order to roughen the inner surface of the belt, it is necessary to use something like an inner mandrel with a newly roughened surface.

The extruded seamless belt is electrically conductive,
Required properties such as thickness uniformity and mechanical strength must be satisfied 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, more preferably 100 μm or more and 700 μm.
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 smaller, it is not possible to apply the electric charge necessary for transfer unless a high voltage is applied, which not only makes the power supply device costly and large 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.

[0023]

Example As shown in Table 1, each component was supplied to an extruder at a predetermined ratio and kneaded to produce pellets.
A molded product was manufactured from the obtained pellets by the following method, and evaluated using the following method. The results are shown in Table 1. Materials used in Examples and Comparative Examples are as follows. 1. Polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Inc., trade name "Upilon: E-2000") 2. Polybutylene terephthalate (manufactured by Mitsubishi Kasei, trade name "Novadol: 5020") 3. Acetylene black (product name "Denka Black" manufactured by Denki Kagaku) 4. Linear polyethylene (“Mitsubishi Polyethylene LL: UF421” manufactured by Mitsubishi Petrochemical Co., Ltd.) 5. Silicone resin masterbatch (“F029B1” manufactured by Dow Corning) 6. Ethylene tetrafluoroethylene copolymer (Asahi Glass Co., Ltd., trade name "Aflon COP: C55")

The experiments and evaluation methods in Examples and Comparative Examples are as follows. 1. 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. 2. Contact Angle Measurement Test The contact angle of the outer surface of the seamless belt with respect to pure water was measured using a goniometer type contact angle measuring instrument (manufactured by Elma). 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. Friction coefficient test method The measurement was performed using the ASTM D1894-73 slip tester method. Aluminum foil (manufactured by Mitsubishi Aluminum Co., Ltd .: diamond foil) was wrapped around the sled as an opponent at that time. 5. Roll-sliding property A seamless belt with a width of 200 mm is used with both roll diameters of 25φ.
mm, roll speed 100 mm / sec, belt tension 8 k
The condition of g / belt full width, 25 ° C., 55% was set in the apparatus of FIG. 2 and the deviation between the belt and the roll was visually observed.

The present invention will be further described below with reference to specific examples. (Examples 1 to 3) 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 melting tube was mounted on the same axis of the annular die via a support rod, RMax2
A seamless tube was obtained by contacting with the outer surface of a 130 mmφ cooling mandrel having a surface roughness of 0 μ and solidifying by cooling. Next, with the core installed in the seamless tube and the roll installed on the outside, the seamless tube (cut into a predetermined length is a seamless belt) is taken in while maintaining the cylindrical shape. It was Conductivity of the obtained belt, contact angle, toner adhesion, friction coefficient,
The slipperiness with the roller was evaluated. The evaluation results are shown in Table 1.

(Example 4) 13 of Examples 1 to 3
Evaluation was performed in the same manner as in Examples 1 to 3 except that the surface roughness of the 0 mmφ cooling mandrel was set to RMax 1 μm or less and the inner surface of the finished seamless belt was roughened with an abrasive (Sumitomo 3M: Imperial Lapping Film # 400). did.

(Comparative Example 1) With the composition shown in Table 1, a 40φ extruder with an annular die was used to extrude below the annular die in a molten tube state, and the extruded molten tube was the same as that of the annular die. The surface mounted via a support rod on the axis is in contact with the outer surface of the cooling mandrel of 130 mmφ of RMax 20μ to be cooled and solidified to form a seamless tube, which is then installed inside and outside the core installed in the seamless tube. Seamless tube (seamless belt cut to a specified length) depending on the roll
Was taken while holding the cylinder. The conductivity, contact angle, toner adhesion, friction coefficient, and sliding property of the obtained belt were evaluated. The evaluation results are shown in Table 1.

(Comparative Examples 2 and 3) In Comparative Example 1, 13
Evaluation was performed in the same manner as in Comparative Example 1 except that the surface roughness of the 0 mmφ cooling mandrel was set to RMax1 μm or less.

Comparative Example 4 In Comparative Example 1, 130 m
The evaluation was performed in the same manner as Comparative Example 1 except that the cooling mandrel surface roughness of mφ was set to RMax 1 μm or less and the inner surface of the finished seamless belt was roughened by using an abrasive (Sumitomo 3M: Imperial Lapping Film # 4000).

[0030]

[Table 1]

[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

Claims (2)

[Claims] 1. Regarding the wettability of the seamless belt, when the outer surface of the seamless belt is used as a test piece and water is dropped, the contact angle between the test piece flat surface and the water drop is 90 ° or more, and the dynamic friction coefficient of the inner side surface is ASTM. A seamless belt that is 0.250 or more as measured by D1894-73. 2. The seamless belt according to claim 1, wherein the surface conductivity of the outer surface and the inner surface is 1 × 10 ⁰ to 1 × 10 ¹³ Ω / □.