JP2002214926A - Endless belt member and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endless belt member by which elongation and contraction at a running time are reduced and an image having excellent quality is obtained. SOLUTION: The endless belt member used in an image forming device to form the image by passing through an electrifying process, an image exposure process, a developing process and a transfer process is constituted of at least two or more layers, and at least a first layer which is a most back face is obtained by the extrusion molding of a thermoplastic resin by the extruder of a ring-like die, and the Young's elastic modulus of a material constituting the first layer is set >=20000 kg/cm2, and tensile strength is set >=500 kg/cm2, and also the hardness of a material constituting a second layer at least positioned on a surface side from the first layer is set <=D85, and break elongation is set >=50%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endless belt member used as an intermediate transfer member or a transfer member, and an image forming apparatus having the same.

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer member includes:
A color image forming apparatus, a multi-color image forming apparatus, or a color image forming apparatus that sequentially transfers a plurality of component color images of color image information or multi-color image information and outputs an image formed product by combining and reproducing the color image or the multi-color image. It is effective as an image forming apparatus having a function and a multicolor image forming function.

FIG. 1 shows an example of an image forming apparatus using an intermediate transfer belt as an intermediate transfer member.

FIG. 1 is a cross-sectional view of a main part of a color image forming apparatus (copier or laser beam printer) using an electrophotographic process. An intermediate transfer belt 20 of the color image forming apparatus has a medium resistance resin film. It is used.

In FIG. 1, reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (repeatedly used as a first image carrier).
This is hereinafter referred to as a photosensitive drum), which is rotationally driven at a predetermined peripheral speed (process speed) in a clockwise direction shown by an arrow in the figure.

In the course of rotation, the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a primary charger 2, and then is subjected to image exposure means (not shown) such as a color original image color separation / imaging exposure optical system. A first color component image of a target color image by receiving image exposure 3 by a scanning exposure system using a laser scanner that outputs a laser beam modulated in accordance with a time-series electric digital pixel signal of a system and image information. (For example, a yellow component image) is formed.

Then, the electrostatic latent image is developed by a first developing device (yellow developing device 41) with yellow toner Y as a first color. At this time, the developing units of the second to fourth developing units (the magenta developing unit 42, the cyan developing unit 43, and the black developing unit 44) are turned off and do not act on the photosensitive drum 1; The first color yellow toner image is not affected by the second to fourth developing units 42, 43, and 44.

The intermediate transfer belt 20 is driven to rotate clockwise at the same peripheral speed as the photosensitive drum 1.

[0009] The first type formed and supported on the photosensitive drum 1
In the process of passing through the nip portion between the photosensitive drum 1 and the intermediate transfer belt 20, the yellow toner image of the intermediate color is formed by an electric field formed by the primary transfer bias applied from the primary transfer roller 62 to the intermediate transfer belt 20. Transfer belt 2
0 is sequentially transferred to the outer peripheral surface (primary transfer).

The photosensitive drum 1 on which the transfer of the first color yellow toner image corresponding to the intermediate transfer belt 20 has been completed.
Is cleaned by the cleaning device 13.

Hereinafter, similarly, a magenta toner image of the second color, a cyan toner image of the third color, and a black toner image of the fourth color are sequentially superimposed on the intermediate transfer belt 20 and transferred to correspond to the target color image. Thus, a combined color toner image is formed.

Reference numeral 63 denotes a secondary transfer roller, which is a secondary transfer roller.
It is supported in parallel with the next transfer opposing roller 64 and is disposed on the lower surface of the intermediate transfer belt 20 so as to be separated therefrom.

A primary transfer bias for sequentially superimposing transfer of toner images of the first to fourth colors from the photosensitive drum 1 to the intermediate transfer belt 20 is applied from a bias power supply 29 with a polarity (+) opposite to that of the toner. You. The applied voltage is, for example, 100 V
２2 kV. In the primary transfer step of the first to third color toner images from the photosensitive drum 1 to the intermediate transfer belt 20, the secondary transfer roller 63 is
It is also possible to move away from.

In transferring the composite color toner image transferred onto the intermediate transfer belt 20 to a transfer material P which is a second image bearing member, a secondary transfer roller 63 is brought into contact with the intermediate transfer belt 20. At the same time, the transfer material P is fed from the paper feed roller 11 through the transfer material guide 10 to the contact nip between the intermediate transfer belt 20 and the secondary transfer roller 63 at a predetermined timing, and the secondary transfer bias is supplied from the power supply 28. The voltage is applied to the secondary transfer roller 63. Then, the composite color toner image is transferred (secondary transfer) from the intermediate transfer belt 20 to the transfer material P as the second image carrier by the secondary transfer bias.

The transfer material P to which the toner image has been transferred is introduced into the fixing device 15 and is subjected to heat fixing of the toner image.
After the image transfer to the transfer material P is completed, the cleaning charging member 7 is brought into contact with the intermediate transfer belt 20, and a bias having a polarity opposite to that of the photosensitive drum 1 is applied to the cleaning charging member 7 to transfer the image. A charge having a polarity opposite to that of the photosensitive drum 1 is applied to the toner (transfer residual toner) remaining on the intermediate transfer belt 20 without being transferred to the material P. 26
Is a bias power supply.

The transfer residual toner is electrostatically transferred to the photosensitive drum 1 in a nip portion with the photosensitive drum 1 and in the vicinity thereof, whereby the intermediate transfer belt 20 is cleaned.

In a color electrophotographic apparatus having an image forming apparatus using the above-mentioned intermediate transfer belt, a second image bearing member is stuck or adsorbed on a transfer drum, which is a conventional technique, and a first image bearing member is attached thereto. A color electrophotographic apparatus having an image forming apparatus for transferring an image from the body, for example,
As compared with the transfer device described in Japanese Patent Application Laid-Open No. 3-301960, the transfer material as the second image carrier requires some processing and control (for example, gripping by a gripper, suctioning, giving a curvature, etc.). Since the image can be transferred from the intermediate transfer belt without performing the printing, thin paper (40 g / m ² paper) such as envelopes, postcards, and label paper can be transferred to thick paper (200 g).
/ M ² paper), the second image bearing member has an advantage that it can be variously selected irrespective of its width, length, or thickness.

Due to such advantages, a color copying machine, a color printer and the like using an intermediate transfer belt have already begun to operate in the market.

As the raw materials of the endless belt used in the image forming apparatus, Japanese Patent Application Laid-Open Nos. 05-200904 and 06-228335 disclose the invention using polyvinylidene fluoride, Japanese Patent Publication No. 08-25232,
JP-A-06-149079, Patent No. 279235
No. 9 discloses ethylene tetrafluoroethylene (ETF).
E) and / or ethylene fluorochloroethylene (EC
Invention using TFE) and Japanese Patent Application Laid-Open No. 06-2349.
No. 03 and JP-A-08-224802 disclose inventions using a fluororesin. These fluorine-based materials have low mechanical elastic properties, such as tensile modulus and tensile strength, and cause elongation when the belt is run by a driving roller or the like, causing image displacement during transfer and dimensional accuracy. May worsen.

On the other hand, Japanese Patent Application Laid-Open No. 05-311016,
Japanese Patent Application Laid-Open No. 07-024912 discloses an olefin-based film. However, most of olefin-based films and belts have a resin property of elongation at break of 400% or more. The belt gradually relaxes, slips, meanders, rides,
Problems such as peripheral speed instability occur.

Further, Japanese Patent Application Laid-Open Nos. 06-149081 and 06-149083 disclose a belt tube made of polyalkylene terephthalate (PAT). Polyalkylene terephthalate has a high hardness as a resin property and a small elongation at break (that is, lacks flexibility). For example, when a cylindrical photoreceptor or a bias roll is pressed against a belt, the belt is pressed by a pressing force. Not enough deformation. When the transfer is performed in this state, the load on the belt becomes non-uniform. For example, when an endless belt is used as an intermediate transfer member, the image may be lost, and the transfer efficiency in the primary transfer and the secondary transfer may be reduced. In addition, when the transfer material is used as a transfer belt, there is a problem that the transfer material is displaced due to insufficient suction of the transfer material.

On the other hand, various methods for producing an endless belt are already known. For example, Japanese Patent Application Laid-Open No. 10-631
No. 15, JP-A-5-26949 discloses a method of obtaining a belt by connecting sheets to form a cylindrical shape. Also, Japanese Patent Application Laid-Open No. 9-269674
Japanese Patent Application Laid-Open Publication No. H11-139,086 discloses a method of forming a multilayer coating film on a cylindrical substrate and finally removing the substrate to obtain a belt.

Furthermore, Japanese Patent Application Laid-Open No. 5-77252 discloses that
There is a disclosure of a seamless belt by a centrifugal molding method.

[0024]

However, each of the above manufacturing methods has the following disadvantages.

That is, the method of joining sheets involves a problem of a step at joints and a decrease in tensile strength. Methods using a solvent, such as cast molding, coating, and centrifugal molding, increase the number of steps and cost, such as production of a coating solution, coating, and removal of the solvent. Furthermore, there are also problems that affect the environment, such as solvent recovery.

Accordingly, an object of the present invention is to provide an endless belt member capable of obtaining a high quality image with little expansion and contraction during running, and an image forming apparatus including the same.

Further, an object of the present invention is to provide an endless belt which is free from troubles such as slipping, meandering, climbing, unstable peripheral speed and the like and which does not cause deterioration such as cracking and tearing even under severe endurance use due to repeated use. An object of the present invention is to provide a member and an image forming apparatus including the member.

[0028]

In order to achieve the above object, a charging step of applying a charge to an electrophotographic photosensitive member, an image exposing step of forming an electrostatic latent image on the electrophotographic photosensitive member, An endless belt member used in an image forming apparatus for forming an image through a developing step of forming a visible image by developing with a toner and a transfer step of transferring a toner image to a transfer material has at least two layers or more. At least the first layer, which is the rearmost surface, is obtained by extruding a thermoplastic resin with an annular die of an extruder, and the material constituting the first layer has a Young's modulus of 2000.
0 kg / cm ² or more, tensile strength 500 kg / cm ²
The hardness of a material constituting at least the second layer located on the surface side of the first layer is D85 or less, and the breaking elongation is 50% or more.

Further, the present invention provides a charging step of applying a charge to an electrophotographic photosensitive member, an image exposing step of forming an electrostatic latent image on the electrophotographic photosensitive member, and developing the electrostatic latent image by developing it with toner. In an image forming apparatus for forming an image through a developing step of forming an image and a transfer step of transferring a toner image to a transfer material, the endless belt member is used as an intermediate transfer member or a transfer member.

[0030]

Embodiments of the present invention will be described below.

The present invention comprises a charging step of applying a charge to an electrophotographic photosensitive member, an image exposing step of forming an electrostatic latent image on the electrophotographic photosensitive member, and a visible image by developing the electrostatic latent image with toner. Endless belt member used in an image forming apparatus that forms an image through a developing step of forming a toner image and a transfer step of transferring a toner image to a transfer material, the endless belt member has a configuration of at least two layers, The first layer, which is the back surface, is obtained by extruding a thermoplastic resin with an annular die of an extruder;
The material constituting the layer has a Young's modulus of 20,000 kg / c.
m ² or more, a tensile strength of 500 kg / cm ² or more, and at least a second layer located on the surface more than the first layer.
The hardness of the material constituting the layer is D85 or less, and the elongation at break is 50
% Or more.

Here, the first layer refers to the back surface of the endless belt that directly contacts the drive roller. The material constituting the first layer has a Young's modulus of 20,000 kg / cm ^2.
If the mechanical strength is less than 500 kg / cm ² and the tensile strength is less than 500 kg / cm ² , the amount of deformation of the belt with respect to stress increases when the belt is driven by the driving roller,
The image becomes unstable, for example, a position shift occurs in the image. The Young's modulus of the material constituting the first layer is 2000
0 kg / cm ² or more, more preferably 35,000 kg / cm ² or more, and the tensile strength is 500 kg / c
m ² or more, and more preferably 1000 kg / cm ² or more.

The material forming the first layer has a breaking elongation of 3
If it exceeds 00%, it is not preferable because the adhesion between the first layer and the other layer adjacent to the first layer is reduced by repeated use of the belt, in addition to the deterioration of the image quality. The elongation at break of the material constituting the first layer is preferably 300% or less, more preferably 100% or less.

On the other hand, the second layer located closer to the photosensitive member than the first layer
The hardness of the material constituting the layer is D85 or more,
If the elongation at break is inferior to 50% or less, the deformation of the belt due to the pressing force when the belt is pressed against, for example, a cylindrical photosensitive member or a bias roll becomes insufficient. When the transfer is performed in this state, the load on the belt is partially concentrated and non-uniform. For example, when an endless belt is used as an intermediate transfer member, an image may be missing, or the primary transfer and the secondary transfer may not be performed. Transfer efficiency may be reduced. In particular, in the secondary transfer, this tendency is remarkable when the transfer material has a rough surface such as paper.

When an endless belt having insufficient flexibility of the second layer is used as a transfer belt, the transfer material is not sufficiently attracted, the position of the transfer material on the endless belt becomes unstable, and the image quality is reduced. Is reduced. Also in this case, this tendency is remarkable when the transfer material has a rough surface such as paper.

The hardness of the material constituting the second layer is preferably D85 or less, more preferably D80 or less, and the elongation at break is preferably 50% or more, more preferably 100% or more. Furthermore, for the reasons stated above, the Young's modulus of the material constituting the second layer, 20000 kg / cm ² or less, it is preferable tensile strength is 1000 kg / cm ² or less. In the present invention, the method for measuring the Young's modulus, tensile strength and elongation at break conforms to ASTM-D638.
In the present invention, the hardness is measured according to JIS-K-72.
15 The sample thickness at the time of hardness measurement is 6 mm.

The layer structure of the endless belt material according to the present invention may be any structure as long as the first layer is located on the rearmost surface and has two or more layers. The first layer and the second layer need not necessarily be adjacent to each other, and another third layer may be present on the second layer. However, if the third layer is made of a material that does not satisfy the physical properties of the second layer, the third film thickness is 10 μm or less, and more preferably 5 μm, in order not to impair the properties of the second layer.
It is preferably not more than μm.

As the resin used for the first layer, materials having excellent mechanical strength include, for example, polyimide, polyamide imide, polyether imide, polyethylene terephthalate, polycarbonate, polyacetal, polyarylate, polyphenylene sulfide, polysulfone, and polyether sulfone. And polyether ether ketone. The above resins may be used alone, or may be appropriately mixed and used. In order to further impart mechanical strength to these resins, various reinforcing materials may be mixed.

The reinforcing material is preferably a fibrous or whisker-like material. Examples of the fibrous reinforcement include glass fiber, carbon fiber, ceramic fiber, silicon carbide fiber, boron fiber, alumina fiber, copper fiber, magnesium fiber,
Examples include stainless steel fibers, aluminum fibers, and titanium oxide fibers.

Examples of the whisker-like reinforcing material include potassium titanate whiskers, silicon carbide whiskers, silicon nitride whiskers, graphite whiskers, copper oxide whiskers, and aluminum borate whiskers. The compounding amount of these reinforcing materials is preferably 60% by weight or less, more preferably 50% by weight or less based on the whole material. If the compounding amount of the reinforcing material is excessive, the fluidity at the time of extrusion becomes insufficient, which adversely affects the formability. Specifically, it is difficult to control to a desired size after extrusion. Alternatively, bumps, fish eyes and perforations due to the reinforcing material are likely to occur.

Examples of the material having excellent flexibility used for the second layer include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), ethylene fluorochloroethylene (ECTFE), and fluorine. In addition to fluorine-based materials such as fluorinated ethylene propylene copolymer (FEP) and tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), polyethylene, ethylene-vinyl chloride copolymer, ethylene vinyl alcohol copolymer (EVOH),
Resins such as polypropylene, polystyrene, methacryl, polyamide, and polyvinyl chloride (PVC), rubber materials such as nitrile butadiene rubber, ethylene propylene rubber, and chloroprene rubber, urethane-based elastomers, and styrene-based elastomers.

In order to control the volume resistance and surface resistance of the endless belt material in the present invention, a resistance control material may be added to the first and second layers as long as the properties of each layer are not impaired. Among the resistance control materials, examples of the electron conductive resistance control material include carbon black, graphite, aluminum-doped zinc oxide, tin oxide-coated titanium oxide, tin oxide, tin oxide-coated barium sulfate, potassium titanate, aluminum metal powder, nickel Metal powder and the like.

Examples of the ionic conductive resistance controlling material include tetraalkylammonium salts, trialkylbenzylammonium salts, alkyl sulfonates, alkylbenzene sulfonates, alkyl sulfates, sorbitan fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene alkylamines, and polyoxyethylene alkylamines. Examples thereof include ethylene fatty acid alcohol esters, alkyl betaines, and lithium perchlorate.

Next, a method of forming a belt shape using these materials will be described.

FIG. 2 shows a molding apparatus according to the present invention. The device basically consists of an extruder, an annular die and an air blowing device.

FIG. 2 shows two extruders 100 and 110 for forming a two-layer belt, but at least one or more extruders may be used in the present invention.

Next, a method for producing the first layer of the endless belt according to the present invention will be described.

First, a molding resin, a conductive agent, an additive, and the like are preliminarily mixed based on a desired formulation, and then the kneaded and dispersed molding materials are put into a hopper 120 provided in the extruder 100. The extruder 100 has a melt viscosity at which the raw material for molding can be used to form a belt in a subsequent process,
The set temperature and the screw configuration of the extruder are selected so that the raw materials are evenly dispersed.

The raw material for molding is melted and kneaded in the extruder 100 to form a melt, and enters the annular die 140. The extrusion die 140 is provided with an air introduction path 150. When air is blown into the annular die 140 from the air introduction path 150, the melt passing through the die 140 expands and expands in the radial direction. At this time, nitrogen, carbon dioxide, argon, etc., other than air, can be selected as the gas to be blown. The expanded molding is cooled with a cooling ring 160.
It is lifted upward while being cooled by. At this time, the final shape and size 180 are determined by passing between the dimensional stability guides 170. Further, by cutting this into a desired width, the belt 190 according to the present invention can be obtained.

The second layer or other layers may be extruded simultaneously with the first layer by the same extrusion molding method as that for the first layer to perform multilayer molding. For example, when the first layer and the second layer are co-extruded, an extruder 110 is further arranged as shown in FIG. 2, and the extruder 100 is extruded simultaneously with the kneaded melt of the extruder 100 into an annular die 140 for two layers. Machine 11
The kneaded melt of No. 0 is fed and two layers are simultaneously expanded and expanded to obtain a two-layer belt.

Of course, when simultaneously extruding three or more layers,
An extruder may be prepared according to the number of layers. FIG.
FIG. 4 shows an example of a two-layer and three-layer belt.

According to the present method, it is possible to form a multi-layered belt in one step and with high dimensional accuracy in a short time. The fact that short-time molding is possible fully suggests that mass production and low-cost production are possible.

In the extrusion method of the present invention, it is preferable that the thickness of the formed tube film is smaller than the die gap of the annular die. If a molded product of 150 μm is formed with a die gap of 150 μm, a deflection of 1 μm in the die gap appears almost as it is in the variation of the thickness of the molded product, and it is difficult to obtain the thickness accuracy of the molded product.
When a molded product having a die gap of 150 μm is formed, a deviation of 1 μm in the die gap has little effect on the molded product thickness, and a molded product with high thickness accuracy can be obtained.

Further, it is preferable to set the take-up speed of the cooled and formed tubular film faster than the discharge speed of the tubular melt discharged from the tip of the annular die. Thereby, a stretching effect is added, and it is easy to realize a molded product thinner than the die gap as described above.

It is preferable that the diameter of the formed tube film is in the range of 50 to 300% with respect to the die diameter of the annular die. This makes it easier to obtain a molded product thinner than the die gap as described above. In particular, when using a resin that has a low melt tension and cannot be expanded, the diameter of the tube film is preferably set in the range of 50 to 100%.

In the present invention, the extruder for extruding the tubular melt is preferably a twin screw extruder. Due to the compounding effect of the twin-screw extruder, the kneading / dispersing step of the conductive material into the thermoplastic resin and the extrusion step are performed in one step.
This is realized in the process, and the cost can be reduced by reducing the number of processes.

In the present invention, the first layer is obtained by the extrusion molding as described above, and the second layer and / or other layers are applied on the first layer belt to form a multilayer belt. May be. Examples of the application method include spray, dip, and flow coat. In particular, when forming a thin film of the third layer on the second layer for the purpose of imparting releasability,
Layer formation by coating is preferred.

The volume resistance of the belt produced by the above method is preferably in the range of 10 ⁰ to 10 ¹⁴ Ω, and
More preferably, it is in the range of 0 ³ to 10 ¹² Ω.

It is preferable that the maximum value of the belt volume resistance (Ω) in the circumferential direction is within 100 times the minimum value. If the ratio between the maximum value and the minimum value exceeds 100 times, transfer unevenness occurs in the circumferential direction of the belt, or when a voltage is applied to a plurality of places, the voltage is applied from some places to another place. A current may flow into a certain location through a portion having a low resistance in the circumferential direction, and normal operation may not be performed due to disturbance of voltage control in other locations.

On the other hand, also with respect to the surface resistance (Q) of the belt, it is preferable that the maximum value of the surface resistance (Ω) in the circumferential direction be within 100 times the minimum value, as in the case of the volume resistance described above. If the ratio between the maximum value and the minimum value exceeds 100 times, transfer unevenness occurs in the circumferential direction of the belt, or when a voltage is applied to a plurality of places, the voltage is applied from some places to another place. A current may flow into a certain location through a portion having a low resistance in the circumferential direction, and normal operation may not be performed due to disturbance of voltage control in other locations.

Further, the maximum value of the volume resistance (Ω) is preferably within 100 times the minimum value in the longitudinal direction of the belt. When the ratio between the maximum value and the minimum value exceeds 100 times, transfer unevenness occurs in the longitudinal direction of the belt,
Excessive current may flow into the region where the resistance is minimum, and the device may malfunction.

Similarly, the maximum value in the longitudinal direction of the surface resistance (Ω) of the belt is preferably within 100 times the minimum value. If the ratio of the maximum value to the minimum value exceeds 100 times, transfer unevenness occurs in the longitudinal direction of the belt, or in the case of ICL, an excessive current flows into the minimum surface resistance portion, and a sufficient electric field is generated in the longitudinal direction of the portion. Since it is not applied, cleaning unevenness may occur in the longitudinal direction.

In the present invention, the volume resistance and the surface resistance show independent electric characteristics. That is, when the voltage / current applied to the belt is applied in the thickness direction, the movement of the electric charge in the belt mainly depends on the structure and physical properties inside the belt, in other words, the layer configuration of the belt, the additive, and the dispersion state. Is determined, and as a result, the surface potential and the static elimination speed of the belt are determined.

On the other hand, when a voltage or a current is applied so that charges are transferred only on the surface of the belt, the additive and the resistance control agent on the surface are hardly dependent on the internal structure and the layer structure of the belt. The surface potential, static elimination speed and the like are determined only by the existence ratio. In the present invention, realizing a favorable state for any of the above two resistors is a necessary condition for maintaining transfer efficiency and obtaining good image quality without transfer failure.

The method of measuring the volume resistance and the surface resistance in the present invention is as follows. (Measuring method of surface resistance and volume resistivity) <Measuring machine> Resistance meter; Ultra high resistance meter R8340A (manufactured by Advantest) Sample box; 41m inside diameter
m, guard ring outer diameter 49 mm) <Sample> Cut the belt into a circle having a diameter of 56 mm.
After cutting, one surface is provided with electrodes on the entire surface by a Pt-Pd vapor-deposited film, and the other surface has a diameter of 2
A 5 mm main electrode and a guard electrode having an inner diameter of 38 mm and an outer diameter of 50 mm are provided. The Pt-Pd vapor-deposited film can be obtained by performing a vapor-deposition operation with mild sputter E1030 (manufactured by Hitachi, Ltd.) for 2 minutes. The sample after the vapor deposition operation is used as a measurement sample.

<Measurement Conditions> Measurement atmosphere: 23 ° C./55% (measurement sample is left in an atmosphere of 23 ° C./55% in advance for 12 hours or more) Measurement mode: program mode 5
(Discharge 10 seconds, charge and measure 30
Second) applied voltage; 1 to 1000 (V) The applied voltage is a range of 1 to 1 which is a range of a voltage applied to the intermediate transfer body and the transfer member used in the image forming apparatus of the present invention.
000V can be arbitrarily selected. Further, the applied voltage used can be changed as appropriate within the range of the applied voltage according to the resistance value, thickness, dielectric breakdown strength and the like of the sample.

If the volume resistivity and the surface resistance at a plurality of points measured at any one of the applied voltages are included in the resistance range of the present invention, the resistance range is the object of the present invention. Is determined.

Hereinafter, the present invention will be described in detail with reference to examples.

<Example 1> As the material constituting the first layer, the following raw materials were mixed and kneaded with a biaxial extruder.
This was dispersed to obtain a molding raw material (1).

Polyphenylene sulfide resin 100 parts by weight Conductive carbon black 20 parts by weight Antioxidant 0.5 part by weight The polyphenylene sulfide resin is a resin in which 30% of glass fiber is mixed as a reinforcing material. When the mechanical properties of the molding material (1) were measured in accordance with ASTM-D638, the Young's modulus was 140000 kg / cm.
² , tensile strength was 1520 kg / cm ² , and elongation at break was 1.5%.

Next, the molding raw material (1) was kneaded with a particle size of 1 to 2 mm. As in the case of the first layer, the following raw materials were kneaded and dispersed by a biaxial extruder to obtain a molding raw material (2).

100 parts by weight of fluorinated ethylene-propylene copolymer (FEP) 5 parts by weight of conductive carbon black 1.5 parts by weight of lithium perchlorate 0.5 part by weight of antioxidant 0.5 parts by weight It was D62 when measured according to -K-7215. The elongation at break was measured in accordance with ASTM-D638 and found to be 280
%Met. Furthermore, when the Young's modulus and the tensile strength were measured in accordance with ASTM-D638, each was 34
It was 00 kg / cm ² and 270 kg / cm ² .

Next, similarly to the molding raw material (1), the molding raw material (2) was kneaded with a particle size of 1 to 2 mm.

Next, the kneaded material for the first layer is put into the hopper 120 of the single-screw extruder 100 shown in FIG. A melt was obtained by extruding while adjusting the temperature in the range of 290 ° C to 350 ° C. Each melt was subsequently guided to a cylindrical two-layer extrusion die 140. The outer diameter of the die mandrel of the die is 110 mm, and the die gap is 250 μm. Further, there, air is blown in from the air introduction passage 150 to expand and expand, and the final shape and dimensions 180 are 145 mm in inner diameter, and the thickness of the first layer is 4 mm.
0 μm, and the thickness of the second layer was 50 μm. The discharge speed of the melt at this time was 4.5 m / min, and the take-up speed of the molded product was 10.0 m / min.

Further, the sheet was cut at a belt width of 250 mm to obtain an endless belt. This is referred to as an endless belt belt (1). 50 by the electric resistance measuring machine
When 0 V was applied, the volume resistance of the belt (1) was measured at a total of 18 locations at 6 locations in the circumferential direction and 3 locations in the axial direction at each location, and the variation in resistance in the belt was measured. Has a volume resistance of 6.5 × 10 ^{11 to} 3.2.
× 10 ¹² Ω, and the fluctuation of the volume resistance value at 18 locations was within one digit.

When the surface resistance was measured by the same measuring instrument, the fluctuation of the surface resistance at 18 locations was within one digit.

According to the visual observation of the endless belt (1), no foreign matters such as bumps and fish eyes and defective molding were found on the surface.

This endless belt (1) is shown in FIG.
When the full-color image was printed on 80 g / m ² paper by mounting it in the full-color electrophotographic apparatus shown in (1) and ( ² ), no problems such as misregistration or omission in the image were found.

Further, the transfer efficiency was defined as follows, and the transfer efficiency was measured at a total of 18 locations, 6 locations in the circumferential direction and 3 locations in the axial direction at each location.

Primary transfer efficiency (transfer efficiency from photosensitive drum to intermediate transfer belt) = image density on intermediate transfer belt /
(Transfer residual image density on photosensitive drum + image density on intermediate transfer belt) Secondary transfer efficiency (transfer efficiency from intermediate transfer belt to paper) =
Image density on paper / (image density on paper + transfer residual image density on intermediate transfer belt) In this embodiment, as the photosensitive drum 1, the outermost layer is made of PTFE.
Organic photosensitive drum (OPC photosensitive drum) containing fine powder of Therefore, high primary transfer efficiency was obtained. The primary transfer efficiency and the secondary transfer efficiency are 93 to 95% and 92 to 94%, respectively, in the measurement at all 18 points,
The transfer efficiency hardly fluctuated depending on the measurement location.

The cleaning method for the intermediate transfer belt is a primary transfer simultaneous cleaning method using an elastic roller having a resistance of 1 × 10 ⁸ Ω for the cleaning charging member 7, and can continuously print 40,000 full-color images. went.

No running defects such as meandering, slipping, and running of the belt occurred during the durable operation. Also, cracks,
The surface properties remained the same as those of the initial stage without any abrasion and wear. Further, from the beginning, there was no image density unevenness caused by uneven resistance of the belt, and a good image free from color shift and defective cleaning caused by permanent elongation of the belt was obtained even after running for 40,000 sheets.

<Example 2> As a material constituting the first layer, the following raw materials were kneaded and dispersed by a biaxial extrusion kneader in the same manner as in Example 1 to obtain a molding raw material (3). .

Polysulfone resin 100 parts by weight Conductive carbon black 18 parts by weight Antioxidant 0.5 part by weight The mechanical properties of the molding material (3) were measured according to ASTM-D638, and the Young's modulus was 29000 kg.
/ Cm ² , tensile strength was 1200 kg / cm ² , and elongation at break was 2%.

Next, the molding material (3) was kneaded with a particle size of 1 to 2 mm. Similarly to the first layer, the following raw materials were kneaded and dispersed by a biaxial extruder to obtain a forming raw material (4).

Polyvinylidene fluoride resin 100 parts by weight Tin oxide-coated titanium oxide 25 parts by weight Antioxidant 0.5 parts by weight The hardness of the molding material (4) was measured in accordance with JIS-K-7215. there were. When the elongation at break was measured in accordance with ASTM-D638, it was 320
%Met. Further, when the Young's modulus and the tensile strength were measured in accordance with ASTM-D638, each was 82
It was 00 kg / cm ² and 380 kg / cm ² .

Next, similarly to the molding raw material (3), the molding raw material (4) was kneaded with a particle size of 1 to 2 mm.

Next, using the forming apparatus shown in FIG. 2 in the same manner as in Example 1, a two-layer belt was formed under the same conditions as in Example 1. Here, the difference from Example 1 is that the set temperature at the time of extrusion is 330 to 380 ° C. for the first layer, and 19 ° for the second layer.
This is a portion in the range of 0 to 240 ° C. 140 mm inner diameter, 45 μm thickness of the first layer,
The thickness of the layer was 55 μm. Similarly to Example 1, the endless belt was obtained by cutting at a belt width of 250 mm. This is referred to as an endless belt belt (2).

When the dispersion of the resistance in the belt was measured, the volume resistance value at 18 locations was 5.8 × 10 ^{11 to} 1.0 ×
It was 10 ^{12 12} Ω, and the fluctuation of the volume resistance value at 18 locations was within one digit. When the surface resistance was measured by the same measuring instrument, the fluctuation of the surface resistance at 18 locations was within one digit.

According to the visual observation of the endless belt (2), no foreign matters such as bumps and fish eyes and defective molding were found on the surface.

This endless belt (2) was mounted on a full-color electrophotographic apparatus as an intermediate transfer belt in the same manner as in Example 1, and a full-color image was printed on 80 g / m ² paper. No defects were seen. The primary transfer efficiency and the secondary transfer efficiency were 92 to 95% and 9
1 to 93%, and there was almost no fluctuation in the transfer efficiency depending on the measurement location.

Further, when 40,000 full-color images were continuously printed, running defects such as meandering, slipping, and running of the belt did not occur. Remained sexual. Further, there was no image density unevenness from the beginning, and a good image free from color misregistration and defective cleaning due to permanent elongation of the belt was obtained even after 40,000-sheet running.

<Example 3> As a material constituting the first layer, the following raw materials were mixed and kneaded and dispersed by a biaxial extrusion kneader in the same manner as in Example 1 to obtain a forming raw material (5). Was.

Polyamideimide resin 100 parts by weight Conductive carbon black 22 parts by weight Antioxidant 0.5 part by weight The mechanical properties of the molding material (5) were measured according to ASTM-D638, and the Young's modulus was 55000 kg.
/ Cm ² , tensile strength was 1200 kg / cm ² , and elongation at break was 15%.

As a material for forming the second layer, the following ingredients were mixed to prepare a coating (1) for forming a second layer.

Polytetrafluoroethylene resin 100 parts by weight Methyl ethyl ketone 250 parts by weight DMF 1200 parts by weight A paint (1) is applied to an aluminum plate, dried, and then peeled off from the aluminum plate to prepare a sheet. When measured according to 7215, D6
It was 0. Further, the elongation at break of the sheet was measured according to ASTM-D6.
When measured in accordance with No. 38, it was 350%. Further, when the Young's modulus and the tensile strength were measured in accordance with ASTM-D638, each was 4000 kg / cm.
² , 300 kg / cm ² .

Next, a single-layer belt was formed using a single-layer die using the forming apparatus shown in FIG. 2 in the same manner as in Example 1. Here, the set temperature at the time of extrusion is 330 to 380 ° C.
And the discharge speed of the melt was 4.5 m / min, and the take-off speed of the molded product was 10.0 m / min. The outer diameter of the die mandrel of the single-layer die is 110 mm, and the die gap is 250 μm. A single layer belt having an inner diameter of 140 mm, a thickness of 100 μm, and a width of 250 mm was obtained as the shape and dimensions after molding and cutting.

Next, after coating the second layer paint (1) on the surface of the single layer belt by spray coating,
Dry at 0 ° C. to form a second layer having a thickness of 30 μm,
An endless belt (3) having a two-layer structure was obtained. When the variation of the resistance in the belt was measured, the volume resistance value at 18 locations was 1.0 × 10 ^{13 to} 7.5 × 10 ¹³ Ω, and the fluctuation of the volume resistance value at 18 locations was within one digit. Was.

When the surface resistance was measured by the same measuring instrument, the fluctuation of the surface resistance at 18 locations was within one digit.

According to the visual observation of the endless belt (3), no foreign matters such as bumps and fish eyes and poor molding were found on the surface.

The endless belt (3) was mounted on a full-color electrophotographic apparatus as a transfer belt for transferring a transfer material, and a full-color image was printed on 80 g / m ² paper. Was.

Further, when 40,000 full-color images were continuously printed, running defects such as meandering, slipping, and running of the belt did not occur. Remained sexual.

Comparative Example 1 In Example 1, kneading and dispersion were performed in the same manner as in Example 1 except that the materials of the first layer were mixed as follows.

Formulation for first layer: 100 parts by weight of ethylene tetrafluoroethylene (ETFE) 18 parts by weight of conductive carbon black 0.5 part by weight of antioxidant Formulation for second layer: Same as in Example 1.

100 parts by weight of fluorinated ethylene propylene copolymer (FEP) 5 parts by weight of conductive carbon black 1.5 parts by weight of lithium perchlorate 0.5 parts by weight of antioxidant 0.5 parts by weight of the kneaded material for the first layer Young modulus is 7000kg
/ Cm ² , tensile strength was 400 kg / cm ² , and elongation at break was 250%.

Next, the respective layers were simultaneously extruded under the same conditions as in Example 1, and the inner diameter was 145 mm and the thickness of the first layer was 50 μm.
m, a two-layer endless belt having a second layer thickness of 45 μm and a width of 250 mm was obtained. In the endless belt, the run-out in the belt of the volume resistance and the surface resistance was within one digit.

Further, according to visual observation of the surface, no foreign matters such as bumps and fish eyes and defective molding were found.

The endless belt was mounted on a full-color electrophotographic apparatus as an intermediate transfer belt in the same manner as in Example 1, and a full-color image was printed on 80 g / m ² paper. Further, when 40,000 full-color images were continuously printed, the running of the belt was unstable, and slipping and meandering occurred.

<Comparative Example 2> In Example 1, the first layer
The blending of each material of the second layer was performed as follows, and cross-linking and dispersion were performed in the same manner as in Example 1.

Formulation for first layer: same as in Example 1 100 parts by weight of polyphenylene sulfide resin 20 parts by weight of conductive carbon black 0.5 part by weight of antioxidant Formulation for second layer: 100 parts by weight of polybutylene terephthalate conductive carbon Black 5 parts by weight Antioxidant 0.5 parts by weight Here, the hardness of the kneaded material for the second layer was measured according to JIS-K-7215.
It was D90 when measured according to. Also, when the elongation at break was measured in accordance with ASTM-D638,
40%. Further, when the Young's modulus and the tensile strength were measured in accordance with ASTM-D638,
It was 45000 kg / cm ² and 1700 kg / cm ² .

Next, each layer was extruded simultaneously under the same conditions as in Example 1 to obtain an inner diameter of 140 mm and a thickness of the first layer of 40 μm.
m, an endless belt having a two-layer structure with a second layer having a thickness of 43 μm and a width of 250 mm was obtained. In the endless belt, the run-out in the belt of the volume resistance and the surface resistance was within one digit.

Further, by visual observation of the surface, no foreign matters such as bumps and fish eyes and defective molding were not found.

The endless belt was mounted on a full-color electrophotographic apparatus as an intermediate transfer belt in the same manner as in Example 1, and a full-color image was printed on 80 g / m ² paper. Further, the primary transfer efficiency and the secondary transfer efficiency were low at 80 to 82% and 82 to 84%, respectively, in the measurement at all 18 locations.

On the other hand, when this endless belt was mounted as a transfer belt for transferring a transfer material and a full-strength color image was printed on 80 g / m ² paper, the suction of the transfer material was insufficient due to insufficient flexibility of the belt surface. , And a displacement occurred in the image.

<Comparative Example 3> The following raw materials were mixed and dispersed by a twin-screw extruder to obtain a raw material for molding.

Polycarbonate 100 parts by weight Conductive carbon black 15 parts by weight Antioxidant 0.5 part by weight Here, the hardness of the molding material was measured according to JIS-K7215, and was D90. The elongation at break was measured in accordance with ASTM-D638.
20%. Furthermore, when the Young's modulus and the tensile strength were measured in accordance with ASTM-D638,
It was 30,000 kg / cm ² and 700 kg / cm ² .

Next, a single-layer extrusion of the molding material was performed in the same manner as in Example 3 to obtain a single-layer endless belt having an inner diameter of 145 mm, a thickness of 95 mm, and a width of 250 mm. In the endless belt, the fluctuations in the volume resistance and the surface resistance in the belt were all three digits or more.

The endless belt was mounted on a full-color electrophotographic apparatus as an intermediate transfer belt in the same manner as in Example 1, and a full-color image was printed on 80 g / m ² paper. The primary transfer efficiency and the secondary transfer efficiency were as low as 78 to 81% and 80 to 84%, respectively, in the measurement at all 18 points.

On the other hand, when this endless belt was mounted as a transfer belt for transferring a transfer material, and a full-color image was printed on 80 g / m ² paper, misregistration occurred in the image due to sufficient suction of the transfer material.

[0120]

As is apparent from the above description, according to the present invention, by using an endless belt as an intermediate transfer member or a transfer member in an image forming apparatus, high elongation and shrinkage during belt running can be achieved. Image is obtained.

Further, even under severe and durable use due to repeated use, there are no problems such as slip, meandering, running up, and unstable peripheral speed due to relaxation of the belt, and deterioration such as cracking, tearing, and delamination is prevented. Can come off.

Furthermore, a transfer failure of a minute portion of an image does not occur, a blank image does not occur, and a uniform and uniform image quality with extremely high transfer efficiency is achieved.

Further, according to the method of manufacturing an endless belt according to the present invention, it is possible to reduce man-hours, reduce costs and ensure high dimensional accuracy.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of an image forming apparatus according to the present invention.

FIG. 2 is a configuration diagram of a molding device.

FIG. 3 is a partial perspective view of a two-layer belt.

FIG. 4 is a partial perspective view and an overall perspective view of a three-layer belt.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum 2 primary charger 3 image exposure 7 cleaning charging member 13 cleaning device 15 fixing device 20 intermediate transfer belt 28, 29 bias power supply 41-44 developing device 62 primary transfer roller 63 secondary transfer roller 100, 110 Machine 140 annular die

Claims (19)

[Claims] 1. A charging step of applying a charge to an electrophotographic photosensitive member, an image exposing step of forming an electrostatic latent image on the electrophotographic photosensitive member, and a visible image being formed by developing the electrostatic latent image with toner. An endless belt member used in an image forming apparatus that forms an image through a development process and a transfer process of transferring a toner image to a transfer material has at least two layers, and at least the first layer, which is the rearmost surface, is heat. obtained by extrusion molding by an annular die of the extruder the thermoplastic resin, and a Young's modulus of the material constituting the first layer is 20000 kg / cm ² or more, tensile strength is at 500 kg / cm ² or more, at least An endless belt member, wherein the material constituting the second layer located on the surface side of the first layer has a hardness of D85 or less and a breaking elongation of 50% or more. 2. The endless belt member according to claim 1, wherein the elongation at break of the first layer is 300% or less. 3. The tensile modulus of the second layer is 20,000.
an endless belt member as claimed in claim 1, wherein a is kg / cm ² or less. 4. The tensile strength of the second layer is 1000 kg.
The endless belt member according to claim 1, wherein the ratio is not more than / cm ² . 5. The endless belt member according to claim 1, wherein the endless belt member has a two-layer structure of the first layer and the second layer. 6. A method in which at least the first layer is obtained by continuously molding while expanding a tube by blowing a gas having a pressure higher than the atmospheric pressure into a tube-like molten material discharged from a tip of an annular die. The endless belt member according to claim 1, wherein: 7. The endless belt member according to claim 1, wherein at least the first layer is obtained by continuously cutting the formed tubular film in a direction perpendicular to a longitudinal direction. 8. The endless belt member according to claim 1, wherein at least the first layer and the second layer are obtained by co-extrusion. 9. The endless belt member according to claim 1, wherein in the extrusion step, the thickness of the formed tube film is smaller than the die gap of the annular die. 10. A manufacturing method according to claim 1, wherein in the extrusion step, the take-up speed of the tubular film formed by cooling is higher than the discharge speed of the tubular melt discharged from the tip of the annular die. The endless belt member according to claim 1, which is provided. 11. The endless belt member according to claim 1, wherein in the extrusion step, the diameter of the formed tubular film is 50 to 300% of the die diameter of the annular die. 12. The endless belt member according to claim 1, wherein in the extruding step, a twin screw extruder is used as an extruder for extruding the tubular melt. 13. The endless belt member according to claim 1, wherein at least the second layer is formed by coating. 14. endless belt member according to claim 1, wherein the volume resistivity is characterized in that it is a 10 ⁰ ~10 ¹⁴ 14Ω. 15. The endless belt member according to claim 1, wherein the maximum value of the volume electric resistance in the circumferential direction is within 100 times the minimum value. 16. The endless belt member according to claim 1, wherein the maximum value of the surface electric resistance in the circumferential direction is within 100 times the minimum value. 17. The endless belt member according to claim 1, wherein the maximum value of the volume electric resistance in the longitudinal direction is within 100 times the minimum value. 18. The endless belt member according to claim 1, wherein the maximum value of the surface electric resistance in the longitudinal direction is within 100 times the minimum value. 19. A charging step of applying a charge to the electrophotographic photosensitive member, an image exposing step of forming an electrostatic latent image on the electrophotographic photosensitive member, and forming a visible image by developing the electrostatic latent image with toner. An image forming apparatus for forming an image through a developing step and a transfer step of transferring a toner image to a transfer material, wherein the endless belt member according to claim 1 is used as an intermediate transfer member or a transfer member.