JP2012220839A - Semi-conductive film and electrophotographic image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semi-conductive film that suppresses image failure such as voids even after repeated output of images, and has improved durability as an intermediate transfer body, as well as an image forming apparatus including the semi-conductive film.SOLUTION: A semi-conductive film contains at least a thermoplastic resin, and 19 mass% or more and 30 mass% or less of an acetylene black relative to the thermoplastic resin. The acetylene black has dispersibility index determined from strain dependence of G* of 40% or more, and volume resistivity of 1×10Ω cm or more and 1×10Ω cm or less.

Description

  The present invention relates to a semiconductive film that can be used for an intermediate transfer belt or the like of an electrophotographic image forming apparatus, and an electrophotographic image forming apparatus.

In recent years, various electrophotographic image forming apparatuses such as copying machines and printers have been put on the market. In general, when obtaining a high-quality color image, each color toner image is first developed for each color and then sequentially transferred to an intermediate transfer member to form a color image. Next, the color image formed on the intermediate transfer member is batch-retransferred to the recording medium to obtain a high-quality color image with very little image displacement. The intermediate transfer member used here is generally a semiconductive belt, and a representative belt is obtained by dispersing carbon black in a thermosetting resin polyimide or polyamideimide resin. ing. Such a belt is obtained by forming a coating film of a dispersion obtained by dispersing carbon black in a resin varnish or a polyamic acid varnish which is a resin precursor, and baking it.
On the other hand, recently, studies have been made on a belt obtained by melt extrusion molding a resin composition in which carbon black is dispersed in a thermoplastic resin. Thermoplastic resins are capable of being melt-extruded and have a small amount of organic solvent used, so they are superior to thermosetting resins in terms of environmental impact and cost. . Under such circumstances, in image forming apparatuses that require high speed and high durability, super engineering plastics having high performance in terms of mechanical strength, durability strength, and heat resistance are being studied among thermoplastic resins. Among these, polyetheretherketone (PEEK) is a resin having excellent characteristics such as abrasion resistance, chemical resistance, slidability, toughness, and flame retardancy. Therefore, when used as a semiconductive intermediate transfer belt, a special improvement in performance can be expected (for example, Patent Document 1), and further technical development for that purpose is required.

JP 2005-112942 A JP-A-8-187773 JP 2001-13801 A JP 2002-322327 A

A. R. Payne R.M. E. Whittaker, “LOW STRAIN DYNAMIC PROPERIES OF FILLED RUBBERS”, RUBBER CHEMISTRY AND TECHNOLOGY, 1971, VOL. 44, p. 440-478.

  As described above, engineering plastics and super engineering plastics thermoplastic resins, especially semiconductive films using PEEK, have outstanding mechanical strength characteristics, durability, heat resistance and cost. Things can be expected.

  However, in a conventional semiconductive film using a thermoplastic resin, a phenomenon that causes image defects such as white spots occurs when an image is continuously output repeatedly in a process for obtaining energization and discharge of an intermediate transfer member or the like. There was a case. In particular, there is a strong demand for solving this problem in an image forming apparatus that requires high speed and high durability.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductive film that can be suitably used for an intermediate transfer belt that is less likely to cause image defects than conventional ones even when repeated image output is performed, and has significantly improved durability.

  Another object of the present invention is to provide an electrophotographic image forming apparatus capable of stably forming a high-quality electrophotographic image.

According to one aspect of the present invention, there is provided a semiconductive film having at least a thermoplastic resin and 19% by mass to 30% by mass of acetylene black with respect to the thermoplastic resin,
The semiconductivity in which the dispersibility index of the acetylene black obtained from the strain dependence of G * is 40% or more and the volume resistivity is 1 × 10 ⁹ Ω · cm or more and 1 × 10 ¹² Ω · cm or less. A film is provided.
According to another aspect of the present invention, there is provided an electrophotographic image forming apparatus having the first image carrier and the semiconductive film as an intermediate transfer member.

According to the present invention, it is possible to obtain a semiconductive film in which image defects such as white spots are improved and durability as an intermediate transfer member is improved even if images are continuously output.
Further, according to the present invention, an electrophotographic image forming apparatus capable of stably forming a high-quality electrophotographic image can be obtained.

1 is an explanatory diagram of a configuration of an image forming apparatus using the present invention.

  Hereinafter, the semiconductive film according to the present invention will be described in more detail.

  First, an example of an image forming apparatus to which the present invention can be applied will be described with reference to FIG. An image forming apparatus 100 in FIG. 1 is an electrophotographic color image forming apparatus (color laser printer).

  In the image forming apparatus 100 shown in FIG. 1, each color component of yellow (Y), magenta (M), cyan (C), and black (K) is sequentially arranged in the moving direction along the flat portion of the intermediate transfer belt 7. The image forming units Py, Pm, Pc, and Pk, which are the image forming units, are disposed. Since the basic configuration of each image forming unit is the same, the details of the image forming unit will be described only for the yellow image forming unit Py.

  The yellow image forming unit Py has a drum-type electrophotographic photosensitive member (photosensitive drum) 1Y as an image carrier. The photoreceptor drum 1Y is formed by laminating a photoreceptor layer, a charge transport layer, and a surface protective layer using an aluminum cylinder as a base layer.

  The yellow image forming unit Py includes a charging roller 2Y that is a charge injection charger as a charging unit. By applying a charging bias to the charging roller 2Y, the surface of the photosensitive drum 1Y is uniformly charged.

  Above the photosensitive drum 1Y, a laser beam scanner 3Y as image exposure means is disposed. The laser beam scanner 3Y scans and exposes the surface of the uniformly charged photoreceptor drum 1Y according to image information, and forms an electrostatic latent image of a yellow color component on the surface.

  The electrostatic latent image formed on the photosensitive drum 1Y is developed with toner as a developer by the developing unit 4Y. That is, the developing device 4Y as a developing unit includes a developing roller 4Ya as a developer carrying member, a regulating blade 4Yb as a developer amount regulating member, and contains yellow toner as a developer. The developing roller 4Ya supplied with the yellow toner is in light pressure contact with the photosensitive drum 1Y in the developing portion, and is rotated with a speed difference in the forward direction with respect to the photosensitive drum 1Y. The yellow toner conveyed to the developing unit by the developing roller 4Ya adheres to the electrostatic latent image formed on the photosensitive drum 1Y by applying a developing bias to the developing roller 4Ya. As a result, a visible image (yellow toner image) is formed on the photosensitive drum 1Y.

  The intermediate transfer belt 7 serving as an intermediate transfer member is stretched around a driving roller 71, a tension roller 72, and a driven roller 73, and moves in the direction of the arrow in the drawing in contact with the photosensitive drum 1Y (rotation drive). Is done. The yellow toner image that has reached the primary transfer portion Ty is transferred to the intermediate transfer belt by a primary transfer roller 5Y as a primary transfer member that is pressed against the photoconductive drum 1Y via the intermediate transfer belt 7. 7 is transferred.

  Similarly, the image forming operation described above is performed in each of the magenta (M), cyan (C), and black (K) units Pm, Pc, and Pk as the intermediate transfer belt 7 is moved. Four color toner images of yellow, magenta, cyan, and black are stacked. The four color toner layers are conveyed along with the movement of the intermediate transfer belt 7 and are transferred onto the transfer material S conveyed at a predetermined timing by the secondary transfer roller 8 as the secondary transfer means in the secondary transfer portion T ′. Batch transfer.

  The transfer material S is stored in a cassette 12 which is a transfer material storage portion, separated and supplied into the apparatus by a pickup roller 13, and transferred to the intermediate transfer belt 7 by a conveying roller pair 14 and a registration roller pair 15. In synchronization with the toner image, the toner image is conveyed to the secondary transfer portion T ′.

  The toner image transferred to the transfer material S is fixed by the fixing device 9 and becomes, for example, a full-color image. The fixing device 9 includes a fixing roller 91 including a heating unit and a pressure roller 92, and fixes the unfixed toner image on the transfer material S by heating and pressing.

  Thereafter, the transfer material S is discharged out of the apparatus by the conveying roller pair 16 and the discharge roller pair 17.

  A cleaning blade 11 as a cleaning unit for the intermediate transfer belt 7 is disposed downstream of the secondary transfer portion T ′ in the driving direction of the intermediate transfer belt 7 and is transferred to the transfer material S at the secondary transfer portion T ′. Instead, the transfer residual toner remaining on the intermediate transfer belt 7 is removed.

  As described above, the electrical transfer process of the toner image is repeatedly performed from the photosensitive member to the intermediate transfer belt and from the intermediate transfer belt to the recording medium. Further, by repeating recording on a large number of transfer materials, the electrical transfer process is further repeated. According to the image output test by the present inventors, when such an electrical transfer process is repeated in large quantities, a phenomenon in which the toner is not sufficiently transferred to the transfer material appears. This is likely to occur due to repeated long-time image output, and is visually recognized as an image defect. It is considered that this is caused by concentration of an electric field in a certain part of the intermediate transfer belt in the electric transfer process, denaturation of the resin, and change of the electrical characteristics of the intermediate transfer belt.

Further, the intermediate transfer belt 7 of this embodiment was subjected to resistance adjustment by dispersing acetylene black. The volume resistivity of the intermediate transfer belt 7 is preferably in the range of 10 ⁹ to 10 ¹² Ω · cm, and the surface resistivity is preferably in the range of 10 ⁹ to 10 ¹⁴ Ω / □. By setting the volume resistivity of the intermediate transfer belt 7 within the above range, it is possible to suppress the belt surface from being charged up even when the intermediate transfer belt 7 is continuously driven. As a result, it is not necessary to provide a static elimination mechanism in the electrophotographic image forming apparatus in order to suppress charge-up of the belt surface, and the configuration of the electrophotographic image forming apparatus can be suppressed and the cost can be suppressed.

  Further, for example, when an unintended bias flows to the adjacent primary transfer portions in the primary transfer portions Ty to Tk, it is possible to prevent the transfer bias from becoming insufficient.

  Furthermore, by setting the surface resistivity within the above range, it is possible to suppress the occurrence of peeling discharge when the transfer material S leaves the intermediate transfer belt 7 after passing through the secondary transfer portion T ′. In addition, for example, it is possible to suppress the occurrence of so-called scattering of image defects in which toner is scattered at an unintended place when a dot image is formed. Toner scattering is a phenomenon in which toner that forms the edge of a dot is scattered by the transfer electric field wrapping around a location where toner is not present due to the presence of toner in the lower layer. This phenomenon can be suppressed by setting the surface resistivity of the intermediate transfer belt 7 within the above range.

  The semiconductive film of the present invention is an example in which the above-described intermediate transfer belt is preferably used, but is not limited thereto, and is not limited thereto. Charging belt, roller, developing belt, roller, transfer belt, various blades, recording target The medium conveying belt, the roller, and the like are members used in the same environment and conditions, and the present invention can also be used for these members.

  Hereinafter, the semiconductive film of the present invention will be described in more detail by taking the intermediate transfer belt described in the example of the image forming apparatus as an example.

The intermediate transfer belt 7 which is a semiconductive film according to the present invention includes an ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVdF), polycarbonate (PC), polybutylene terephthalate (PBT), polyethylene terephthalate. Single polymers such as tarate (PET), polyethylene naphthalate (PEN), polysulfone (PSF), polyethersulfone (PES), polyphenyl phonone (PPSF), polyphenylene sulfide (PPS), polyetheretherketone (PEEK) Or it can produce using the thermoplastic resin material containing those copolymers, a blend, an alloy, etc., and acetylene black. In particular, PEEK is preferable as the thermoplastic resin.
In this embodiment, the intermediate transfer belt 7 is manufactured using PEEK as a base.
PEEK used in the present invention is represented by the molecular structure of the following repeating unit.

  Specifically, Victrex PEEK 450G, 381G, 151G, 90G (trade names) and Daicel Degussa's VESTAKEEEP (trade names) are listed, and Solvay is also on the market. These resins can be used alone or in combination of two or more, or can be used by synthesis. When mixed and used, it is preferable to use a mixture of a high molecular weight and a low molecular weight from the viewpoint of reducing the viscosity of the high molecular weight PEEK in the molten state and facilitating processing. Mixing includes kneading in a molten state or mixing in a solution state, but a method of mixing pellets or the like in a molten state is typical. Specifically, the high molecular weight product used is, for example, PEEK 450G or 381G (trade name) manufactured by Victrex, and the low molecular weight products are, for example, 151G and 90G (trade name). Among these, it is preferable to use 450G as a high molecular weight product and 151G as a low molecular weight. The mixing mass ratio of the high molecular weight product and the low molecular weight product is in the range of 40/60 to 75/25, more preferably in the range of 50/50 to 65/35. If it is this range, the mechanical strength of a high molecular weight component will be maintained well and melt viscosity will be reduced effectively.

  Next, acetylene black, which is the carbon black most preferably used for the PEEK resin used in this example, will be described. As described above, acetylene black is a kind of carbon black and is produced from acetylene.

  As a production method, acetylene is obtained by pyrolysis in a preheated furnace. It is said that acetylene black can be obtained at a high speed by an exothermic reaction and by a highly selective reaction, so that high purity carbon black can be obtained. Denka Black (trade name) manufactured by Denki Kagaku Kogyo Co., Ltd. is typical, and can be selected from granular products, general press products, and special press products.

  On the other hand, oil furnace black with good dispersibility intended to control the resistance value generates foreign matters when mixed with PEEK, and it is difficult to obtain a good quality sheet, film or belt. This is presumed that carbon black with a large amount of volatile components at high temperatures such as oil furnace black is mixed with PEEK resin that requires processing at high temperatures, and its volatile components lead to the generation of foreign substances as impurities. .

  Acetylene black is a carbon black that is easy to take a bulky structure, which is said to be a structure unique to carbon black. Therefore, the resin composition has a medium mass resistance with a lower mass fraction than carbon black that does not take such a structure. That is, it can be semiconductive.

  The semiconductive film according to the present invention can be produced by dispersing acetylene black in a thermoplastic resin such as PEEK.

  As a method of dispersing acetylene black in a thermoplastic resin, there are a melt kneading method using a melt kneader and a solution mixing method. Usually, acetylene black is mixed with a biaxial melt kneader or a uniaxial melt kneader. A method of forming a resin composition by melt-kneading a thermoplastic resin is common. In the melt kneading method, a biaxial melt kneader is particularly preferably used.

  Examples of the biaxial melt kneader include HK-25D (trade name, manufactured by Parker Corporation), PCM series (trade name, plastic manufactured by Ikegai Co., Ltd.), and the like.

  In general, when using the same material in a resin composition composed of a thermoplastic resin and carbon black, the smaller the amount of carbon black added to the resin, the higher the resistance value, and when using the same material in the same proportion ratio, The resistance value increases as the carbon black particles are uniformly and finely dispersed. Therefore, it is important to control the dispersion state of carbon black in order to obtain a predetermined resistance value with a predetermined addition amount.

  Since the step of kneading the PEEK resin and acetylene black has a great influence on the dispersion state of the acetylene black in the PEEK resin, in order to obtain the semiconductive film of the present invention, the dispersion is performed depending on the processing conditions of the biaxial melt kneader. It is most effective to control the state. Moreover, when kneading | mixing, the resin pellet and CB can also be atomized previously by grinding | pulverization. As will be described later in specific examples of the present invention, a resin composition of PEEK resin and acetylene black is prepared with a biaxial melt kneader, and a desired dispersion state is created by repeatedly melting and kneading the prepared resin composition. It is possible.

  Next, a semiconductive film can be obtained by a method of extruding the resin composition into a sheet, film or seamless belt by melt extrusion. It can also be molded using a hot press or injection molding. Moreover, there is no limitation in particular in the manufacturing method of the intermediate transfer belt which is an Example of the semiconductive film of this invention, You may use any other manufacturing methods. For example, as a method for obtaining a seamless belt, there are a method in which sheets are formed by extrusion and then joined together to be seamless (see Patent Document 2), and a method in which a cylindrical die is used as an extrusion belt (see Patent Document 3).

  Hereinafter, as an example that can be suitably used in this embodiment, a method of extruding as a seamless body from an annular lip of the die using a melt extruder having a single screw and a spiral annular die will be described. First, a resin composition is put into a melt extruder having a single screw, and the resin composition is extruded as a seamless body from an annular lip of a spiral annular die. A seamless belt can be obtained by controlling the inner diameter by a cooling roll or an internal cooling mandrel system after extrusion and cutting them perpendicularly to the extrusion direction. The die lip clearance is 2.0 mm or less, preferably 1.0 mm or less. The film thickness of the belt of the present invention is preferably 150 μm or less and 30 μm or more for the transfer belt or the intermediate transfer belt, and can be set to a desired thickness by controlling the pulling conditions during extrusion from the die.

  In this embodiment, crystallization treatment is preferably performed for the purpose of enhancing mechanical strength and durability strength, and crystallization can be promoted by annealing at 150 ° C. or higher. Preferably, annealing is performed at 200 ° C. or higher. Annealing may be performed in a constant temperature layer or may be sanded into a metal mold. The degree of crystallinity is a differential scanning calorimeter (DSC), and the crystallization enthalpy of 150 ° C. to 200 ° C .: ΔH peak intensity is preferably less than 20 J / g. More preferably, it is less than 15 J / g, More preferably, it is less than 10 J / g. The DSC can be measured with a device such as DSC7 manufactured by Perkin Elmer, with a temperature increase rate of 5 to 10 ° C./min, a measurement start temperature: 120 ° C., a measurement end temperature of 400 ° C., and a sample mass of about 5 mg.

  The belt according to the present invention prepared in this way is excellent in mechanical strength and durability strength, and is extremely excellent in abrasion resistance, chemical resistance, slidability, toughness, flame retardancy, and the like. For example, when a tensile test is performed according to JIS K 7113, extremely excellent mechanical strength can be expressed. The tensile modulus can be 1.50 GPa or more, 2.0 GPa or more, 2.5 GPa or more, 3.0 GPa or more. Further, the tensile elongation at break can be 10% or more or 20% or more, and it can be seen that it is extremely excellent in terms of toughness. Further, JIS P 8115 is known as a bending fatigue test, but it is also possible to exhibit excellent characteristics. Furthermore, the belt of the present invention can express 0.25 GPa or more in surface hardness, and can be said to be excellent in that sense.

The dispersion state of acetylene black in the semiconductive film of the present invention thus obtained can be known as follows. First, the semiconductive film of the present invention is cut into an appropriate size, placed on a sample table of a rotary rheometer, and the dynamic viscoelasticity is measured while controlling the temperature to a constant temperature so as to be in a molten state. Examine the strain dependence. G * is represented by the magnitude of the vector sum of the storage elastic modulus and the loss elastic modulus as shown in Equation (1).
G * = (G ′ ² + G ″ ² ) ^1/2 formula (1)

In a rubber / acetylene black system, G * exhibits a nonlinear behavior with respect to strain, and a phenomenon in which the value of G * in the linear viscoelastic region depends on the filling amount of acetylene black (so-called Payne effect) is known. Furthermore, it is known that the strain dependence of G * in the rubber / acetylene black system also depends on the dispersion state of acetylene black in the rubber. Conversely, the dispersion state of acetylene black is estimated from the strain dependence of G *. (Non-patent document 1, Patent document 2). In the present invention, it has been found that the dispersibility analysis method used in such a rubber / acetylene black system can be applied to the polymer / acetylene black composite film of the present invention. That is, the dispersion state expressed by G ^* ₁ / G ^* ₂ × 100 can be obtained from the strain dependence of G * obtained by the above experiment, and the dispersion state can be examined. G ^* ₁ is a nonlinear viscoelastic region, and G ^* ₂ is a value of G * in a linear viscoelastic region.

  As a result of intensive studies on the relationship between the dispersibility index obtained in this way and the output image quality degradation phenomenon described above, the output image quality degradation phenomenon is suppressed by using a semiconductive film having a certain range of dispersibility index. I found that I can do it.

  From this, the durability performance can be markedly improved by setting the dispersibility index within the predetermined range from the G * distortion dependency of the intermediate transfer belt using the semiconductive film of the present invention, That is, the stability of the output image quality of the image forming apparatus using the intermediate transfer member of the present invention can be remarkably improved.

  More specifically, in order to improve the durability of the intermediate transfer member, an SUS parallel plate having a diameter of 25 mm or less, preferably 15 mm or less is preferably used at a temperature at which the intermediate transfer body is melted (preferably 340 ° C. or more, more preferably 380 ° C. or more). G * and linear viscoelastic region at a strain of 30% when the strain dependence of G * is measured at a constant frequency in the range of 10 to 0.5 Hz, preferably at a constant frequency in the range of 2.0 to 0.5 Hz. It is preferable that the G * ratio in 100% (for example, strain 0.5%) is 40% or more. More preferably, by setting the ratio of G * at 30% strain to G * at 0.5% strain to be 45% or more, it is possible to remarkably increase the number of repeated image output until the image defect is reached. . Although the mechanism of image degradation due to such repeated image output has not been fully elucidated, electric field concentration occurs when a transfer bias is applied, and a new conductive path is generated due to current concentration and dielectric breakdown. This is presumed to occur. It is presumed that image degradation is suppressed by controlling the dispersion state of the acetylene black in the polymer so that the prescribed dispersibility index falls within a certain range. That is, by realizing a dispersion state in which acetylene black is less aggregated and unevenly distributed, the electric field is not concentrated in part, and generation of a new conductive path can be suppressed, and the electrical conductivity of the semiconductor film of the present invention can be suppressed. It is considered that the deterioration of characteristics can be hardly caused.

The intermediate transfer belt made of the semiconductive film of the present invention exhibits good transfer performance when the volume resistivity is 10 ⁹ Ω · cm or more and 10 ¹² Ω · cm or less. Therefore, in the present invention, acetylene black is dispersed such that the dispersibility index obtained from the strain dependence of G ^* is 40% or more, and the volume resistivity is within the above resistance value range. is necessary. As described above, when the filling amount of the acetylene black with respect to the resin does not change, the higher the dispersion state, the higher the resistance. Therefore, the volume resistivity is 10 ⁹ Ω · cm or more and 10 ¹² Ω · cm or less, and G ^In order to realize a dispersed state of acetylene black such that the dispersibility index obtained from the strain dependency of ^* is 40% or more, there is an optimum range for the filling amount of acetylene black. As a result of intensive studies by the present inventors, it has been found that it is necessary to contain 19% by mass or more of acetylene black with respect to the thermoplastic resin. Further, in order to realize a dispersibility in which the volume resistivity is 10 ⁹ Ω · cm or more and 10 ¹² Ω · cm or less and the dispersibility index obtained from the strain dependence of G * is 45% or more, 22 mass It has been found that it is necessary to contain at least% acetylene black. When the volume resistivity is set to a filling amount that is less than this filling amount, a high dispersion state cannot be realized, so that a phenomenon of lowering the output image quality cannot be prevented. Apart from this viewpoint, since it is necessary to maintain the mechanical strength of the intermediate transfer belt, it is necessary to contain 30% by mass or less of acetylene black with respect to the thermoplastic resin. Further, the more preferable content of acetylene black with respect to the thermoplastic resin is 27% by mass or less, particularly 25% by mass or less.

Examples of the present invention will be specifically described below.
First, the measurement methods and evaluation methods implemented in the following examples will be described together.

(1) Measurement of resistance value (1-1) Volume resistivity Resistivity measuring device (trade name: Hiresta UP, manufactured by Mitsubishi Chemical Corporation) and ring-shaped probe (trade name: URS probe, manufactured by Mitsubishi Chemical Corporation, inner electrode) Of the outer electrode 5.9 mm, outer electrode inner diameter 11.0 mm, outer electrode outer diameter 17.8 mm) and a measurement stage (trade name: register table UFL, manufactured by Mitsubishi Chemical Corporation). Measurement was performed by applying a voltage of 100 V between the electrode (main electrode) inside the probe and the measurement stage while applying a pressure of about 2 kg weight to the sample sandwiched between them.

(1-2) Surface Resistivity A resistivity measuring device (trade name: Hiresta UP, manufactured by Mitsubishi Chemical Corporation) and a ring-shaped probe (trade name: URS probe, manufactured by Mitsubishi Chemical Corporation, outer diameter of inner electrode 5.9 mm, The outer electrode has an inner diameter of 11.0 mm and an outer electrode has an outer diameter of 17.8 mm, and a measurement stage (trade name: register table UFL, manufactured by Mitsubishi Chemical Corporation), and is connected to a sample sandwiched between the probe and the measurement stage. While applying a pressure of 2 kg, measurement was performed by applying a voltage of 100 V between the inner electrode (main electrode) of the probe and the outer electrode (guard electrode) of the probe.

(2) Measurement of strain dependency of G * A semiconductive film was cut into an appropriate size, and 380 ° C. with a dynamic viscoelasticity measuring device (trade name: VAR-100, manufactured by Relogica Instruments AB). Dynamic viscoelasticity was measured under the conditions of a frequency of 1.0 Hz, a φ15 mm SUS parallel plate, and a test piece thickness of 1 mm.

(3) Evaluation of Image Output Durability A film prepared by the method described below is cut into 100 mm × 100 mm, and the cut film is preliminarily formed in the same shape at the center of the intermediate transfer belt 7 of the image forming apparatus 100 shown in FIG. An intermediate transfer belt for evaluation was prepared by pasting on the hole. Evaluation was performed by confirming the output image of the part corresponding to the stuck film part. The evaluation of the intermediate transfer belt in the examples of the present invention was based on the following criteria.
X: A blank image was generated under the following condition (I).
◯: A blank image was not generated under the following condition (I), and a blank image was generated under the following condition (II).
A: No white-out images were generated under the following conditions (I) and (II).

Condition (I)
Evaluation was carried out by repeating transfer to paper, so-called secondary transfer. The paper is CLC80 (manufactured by Nippon Paper Industries Co., Ltd.), and the volume resistivity is about 10 ¹¹ Ω · cm. Assuming that the secondary transfer nip width is 5 mm, the thickness is 85 μm, and the A4 width is 297 mm, the actual resistance is about 6E + 7Ω. The charge amount per unit mass of the toner used is about 30 μC / g in a normal temperature and low humidity environment (23 ° C., 5%). Since the maximum amount of toner formed on the intermediate transfer belt is 12 g / m ² , the maximum charge amount per unit area is 360 μC / m ² . The transfer roller is a roller having a conductive elastic layer having an outer diameter of φ24 mm, a core metal of φ12 mm, and a thickness of 6 mm as a surface layer. Since the secondary transfer nip width is 5 mm, the actual resistance of the transfer nip portion is about 6 × 10. ⁷ Ω. Since the secondary transfer nip width is 5 mm, the thickness of the intermediate transfer belt is 80 μm, and the width is about 300 mm, if the volume resistance is 10 ¹⁰ Ω · cm, for example, at the transfer nip portion of the intermediate transfer belt. The actual resistance is about 2 × 10 ⁷ Ω. The charge amount of the toner in the secondary transfer nip is approximately 0.53 μC by multiplying the secondary transfer nip width of 5 mm and the maximum image width of 300 mm by the maximum charge amount per unit area. Since the process speed is 130 mm / s, the nip passing time is 0.038 seconds (s). The necessary transfer current for necessary transfer is 0.53 / 0.038 = 13.9 μA, but experience shows that the current use efficiency is usually about 40% to 75%. . When 40%, the required transfer current is about 35 μA, and when 75%, it is about 19 μA. Since the combined resistance of the roller, the intermediate transfer belt, and the paper is about 1.4 × 10 ⁸ , the transfer voltage is set to 3.5 kV in consideration of transfer current utilization efficiency. Repeated transfer durability was performed under these conditions, and 20 output images after repeating 300,000 sheets were visually confirmed.

Condition (II)
Regarding the condition (I), the toner was changed to a toner having a lot of pigment components, but the charge amount was the same, and the maximum applied amount was changed from 12 g / m ² to 6 g / m ² . The process speed was changed from 130 mm / s to 300 mm / s, and the nip passage time was set to 0.016 seconds (s). The other conditions were the same as the condition (I). The necessary transfer current is 16.6 μA, but the transfer voltage is set to 4.2 kV in consideration of the current use efficiency. Repeated transfer durability was performed under these conditions, and 20 output images after repeating 600,000 sheets were visually confirmed.

<Example 1>
A PEEK resin blended with 60 parts by mass of Victrex 450G (trade name, manufactured by Victrex) and 40 parts by mass of Victrex 151G (trade name, manufactured by Victrex) was used.

  To this, acetylene black (Denka Black granular product (trade name)) was blended with PEEK so that the addition amount was 19% by mass with respect to PEEK. This was melt-kneaded using a same-direction rotating twin-screw kneading extruder (trade name: HK-25D, manufactured by Parker Corporation) to prepare pellets 11.

  At this time, the screw of the twin-screw kneading extruder is a forward feed type kneading screw, a neutral type kneading screw, a ratio of the reverse feed type kneading screw and the feed screw is 108/60/48/792, and the rotation speed is 500 rpm. went. The pellet 11 was put into the above apparatus and melt-kneaded to prepare a pellet 12. Similarly, melt-kneading was repeated to produce pellets 13 and pellets 14 one after another.

  Using a single screw extruder (trade name: Labo Plast Mill, manufactured by Toyo Seiki Seisakusho), pellets 14 were processed from a T-die having a width of 150 mm and a lip of 350 μm into a film having a thickness of 80 μm by melt extrusion to produce a sheet 1. .

  Next, Table 1 shows the results of measuring the volume resistivity, the surface resistivity, and the strain dependency of G * of the sheet 1 by the above-described methods. Next, the belt image output durability was evaluated by the method described above, and the results are shown in Table 1.

<Example 2>
Pellets 21 were prepared by melt-kneading in the same manner as in Example 1 except that the Denka black granular product was adjusted to an addition amount of 20% by mass. Thereafter, melt kneading was repeated in the same manner as in Example 1 to prepare pellets 22, pellets 23, pellets 24, pellets 25, and pellets 26. The pellets 26 were extruded and processed in the same manner as in Example 1 to produce a sheet 2.
The results of measurement and evaluation on the sheet 2 in the same manner as in Example 1 are shown in Table 1.

<Example 3>
Pellets 31 were prepared by melt-kneading in the same manner as in Example 1 except that the Denka black granular product was adjusted to an addition amount of 21% by mass. Thereafter, melt kneading was repeated in the same manner as in Example 1 to prepare pellets 32, pellets 33, pellets 34, pellets 35, and pellets 36. The pellet 36 was extruded and formed in the same manner as in Example 1 to produce a sheet 3.
The results of measuring and evaluating the sheet 3 in the same manner as in Example 1 are shown in Table 1.

<Example 4>
Pellets 41 were prepared by melt-kneading in the same manner as in Example 1 except that the Denka black granular product was adjusted to an addition amount of 22% by mass. Thereafter, melt-kneading was repeated in the same manner as in Example 1 to prepare pellets 42, pellets 43, pellets 44, pellets 45, pellets 46, pellets 47, and pellets 48. This pellet 48 was extruded and processed in the same manner as in Example 1 to produce a sheet 4.
The results of measurement and evaluation on the sheet 4 in the same manner as in Example 1 are shown in Table 1.

<Example 5>
Pellets 51 were prepared by melt-kneading in the same manner as in Example 1 except that the Denka black granular product was adjusted to an addition amount of 23% by mass. Thereafter, melt kneading was repeated in the same manner as in Example 1 to prepare pellets 52, pellets 53, pellets 54, pellets 55, pellets 56, pellets 57, and pellets 58. The pellets 58 were extruded and processed in the same manner as in Example 1 to produce a sheet 5.
Table 1 shows the results of measurement and evaluation performed on the sheet 5 in the same manner as in Example 1.

<Example 6>
Pellets 60 were prepared by melt-kneading in the same manner as in Example 1 except that the Denka black granular product was adjusted to an addition amount of 24% by mass. Thereafter, melt kneading was repeated in the same manner as in Example 1 to prepare pellet 61, pellet 62, pellet 63, pellet 64, pellet 65, pellet 66, pellet 67, pellet 68, and pellet 69. The pellet 69 was extruded and processed in the same manner as in Example 1 to prepare a sheet 6.
The results of measuring and evaluating the sheet 6 in the same manner as in Example 1 are shown in Table 1.

<Comparative Example 1>
A pellet A1 was prepared by melt-kneading in the same manner as in Example 1 except that the Denka black granular product was adjusted to an addition amount of 19% by mass.
The pellet A1 was extruded and processed in the same manner as in Example 1 to produce a sheet A.
The results of measurement and evaluation for sheet A in the same manner as in Example 1 are shown in Table 1.

<Comparative example 2>
A pellet B1 was prepared by melt-kneading in the same manner as in Example 1 except that the Denka black granular product was adjusted to an addition amount of 18% by mass. Thereafter, melt kneading was repeated in the same manner as in Example 1 to produce pellets B2 and B3.
The pellet B3 was extruded and processed in the same manner as in Example 1 to prepare a sheet B.
The results of measuring and evaluating sheet B in the same manner as in Example 1 are shown in Table 2.

<Comparative Example 3>
Pellets C1 were prepared by melt-kneading in the same manner as in Example 1 except that the Denka black granular product was adjusted to an addition amount of 19% by mass. Thereafter, melt kneading was repeated in the same manner as in Example 1 to prepare pellets C2.
The pellet C2 was extruded and processed in the same manner as in Example 1 to produce a sheet C.
The results of measurement and evaluation for sheet C in the same manner as in Example 1 are shown in Table 2.

<Comparative example 4>
Pellets D1 were prepared by melt-kneading in the same manner as in Example 1 except that the Denka black granular product was adjusted to an addition amount of 20% by mass. Thereafter, melt-kneading was repeated in the same manner as in Example 1 to prepare pellets D2, D3, and pellets D4.
This pellet D4 was extruded and processed in the same manner as in Example 1 to produce a sheet D.

  The results of measuring and evaluating sheet D in the same manner as in Example 1 are shown in Table 2. Note that the initial image quality of the sheet D was low because the initial resistance was low, but the image quality was further deteriorated when the durability evaluation was performed.

<Comparative Example 5>
A pellet E1 was prepared by melt-kneading in the same manner as in Example 1 except that the Denka black granular product was adjusted to an addition amount of 23% by mass. Thereafter, melt kneading was repeated in the same manner as in Example 1 to prepare pellet E2, pellet E3, pellet E4, pellet E5, and pellet E6.
The pellet E6 was extruded and processed in the same manner as in Example 1 to produce a sheet E.
The results obtained by measuring and evaluating the pellet E6 and the sheet E in the same manner as in Example 1 are shown in Table 2.

<Comparative Example 6>
Pellets F1 were prepared by melt-kneading in the same manner as in Example 1 except that the Denka black granular product was adjusted to an addition amount of 24% by mass. Thereafter, melt-kneading was repeated in the same manner as in Example 1 to prepare pellets F2, pellets F3, pellets F4, pellets F5, pellets F6, pellets F7, and pellets F8.
The pellet F8 was extruded and processed in the same manner as in Example 1 to prepare a sheet F.
The results of measurement and evaluation on the sheet F in the same manner as in Example 1 are shown in Table 2.

  The present invention can be used in electrophotographic image forming apparatuses such as copying machines and printers.

1Y, 1M, 1C, 1K Photosensitive drum 2Y, 2M, 2C, 2K Charging roller 3Y, 3M, 3C, 3K Laser beam scanner 4Y, 4M, 4C, 4K Developing means 5Y, 5M, 5C, 5K Primary transfer roller 7 Intermediate Transfer belt 8 Secondary transfer roller 9 Fixing device S Transfer material

Claims (3)

A semiconductive film having at least a thermoplastic resin and 19% by mass to 30% by mass of acetylene black with respect to the thermoplastic resin,
The dispersibility index of the acetylene black determined from the strain dependence of G * is 40% or more, and the volume resistivity is 1 × 10 ⁹ Ω · cm or more and 1 × 10 ¹² Ω · cm or less. A semiconductive film.   The semiconductive film according to claim 1, wherein the thermoplastic resin is polyetheretherketone.   An electrophotographic image forming apparatus comprising an electrophotographic photosensitive member and the semiconductive film according to claim 1 as an intermediate transfer member.