JP2008213268A - Manufacturing method of semiconducting belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconducting belt which can minimize the voltage dependence of an electrical resistance value in a semiconducting belt and inhibit the in-plane dispersion of the electrical resistance value and has electrical characteristics. <P>SOLUTION: This manufacturing method of the semiconducting belt formed of a polyether sulfone-based resin film containing a conducting filler, is to mold the polyether sulfone-based resin containing the conducting filler in a film-like form, and then, perform corona discharge treatment to the film by applying voltage between a discharge electrode 2 and an opposite electrode 3, arranged on the face and back sides of the film 1 respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an electronic material, in particular, a semiconductive belt used as an intermediate transfer belt, a transfer conveyance belt or the like of a color image forming apparatus.

  Mainly in color image forming apparatuses, after a toner image formed on a photoconductor is once transferred, an intermediate transfer belt used to transfer the transferred image onto a transfer material or a toner formed on the photoconductor A semiconductive belt such as a transfer conveyance belt used for directly transferring an image to a transfer material is used.

The semiconductive belt used in these image forming apparatuses is required to be excellent in mechanical strength such as initial elastic modulus in order to form a highly accurate image. As such a semiconductive belt, as shown in Patent Document 1, polyethersulfone (PES), which is a super engineering plastic excellent in mechanical strength, was used and extruded into a cylindrical shape by an extrusion molding device. Later, it is known that this is cut.
JP-A-11-115066

  When the PES is extruded into a cylindrical shape by the extrusion molding apparatus, a circular die is used as the extrusion die. This circular die has a structure in which a cylindrical PES film is extruded from a gap between an inner cylindrical portion and an outer cylindrical portion constituting the die.

  However, the PES film extruded from the extrusion molding apparatus has a problem that the applied voltage depends greatly on the applied voltage. This may be because, when PES is melt-extruded, an extremely thin PES insulating layer is formed on the outermost surface layer. In addition, since a high temperature of 300 ° C. or higher is required to melt-extrude PES, temperature unevenness is inevitably generated in the extrusion molding apparatus, and this temperature unevenness affects the electrical characteristics of the semiconductive film. it was thought.

  When a semiconductive belt is used for the intermediate transfer belt or transfer / conveying belt of the image forming apparatus, and the voltage applied to the belt fluctuates when the electrical resistance value has a large dependency on the applied voltage, the semiconductive belt is accordingly changed. The electrical resistance value fluctuated and this caused image defects. Therefore, a separate device for keeping the voltage applied to the semiconductive belt is necessary, and the cost of the device itself is increased.

  Further, the PES film extruded from the extrusion molding apparatus has a large in-plane variation in electric resistance value, which causes non-uniform toner transfer amounts and causes image defects.

  Therefore, in the present invention, it is possible to reduce the voltage dependence of the electrical resistance value in the semiconductive belt, and it is possible to suppress the in-plane variation of the electrical resistance value, and the semiconductive belt having excellent electrical characteristics. It aims at providing the manufacturing method of.

  In order to solve the above-mentioned problems, the present invention provides a method for producing a semiconductive belt comprising a polyethersulfone (PES) resin film containing a conductive filler, the polyether containing a conductive filler. After the sulfone-based resin is formed into a film, the film is subjected to corona discharge treatment.

  According to the above configuration, it is possible to manufacture a semiconductive belt excellent in electrical characteristics in which the voltage dependence of the electrical resistance value is small and the in-plane variation of the electrical resistance value is suppressed. It should be noted that not only the electrical characteristics (surface resistivity) of the surface of the semiconductive belt but also the volume resistivity, which is the electrical characteristics in the thickness direction of the PES film (hereinafter referred to as PES film), is voltage-dependent. Both the in-plane variation and the in-plane variation are remarkably improved.

  That is, conventionally, corona discharge treatment is generally performed for the purpose of surface modification of plastics and the like. However, as in the present invention, the surface of the semiconductive belt is treated by corona discharge treatment. It has not been anticipated that the voltage dependency and in-plane variation can be improved not only for the resistivity but also for the volume resistivity.

  In order to perform the corona discharge treatment, a PES film is interposed between the discharge electrode and the counter electrode, and the corona discharge is performed in a state where the counter electrode and the PES film are in close contact with each other through a conductive elastic layer. It is preferable to perform the treatment. Thereby, the improvement effect of the said electrical resistance value becomes still higher.

  The reason for this is unclear, but when a conductive elastic layer is interposed between the electrode and the PES film, compared to directly contacting the electrode with a PES film having high rigidity and poor cushioning properties. The PES film can be brought into close contact with the conductive elastic layer without generating a gap.

  This is considered to be because corona discharge treatment can be uniformly applied to the entire PES film in contact with the electrode. Here, the conductive elastic body means an elastic body having a volume resistance lower than that of the semiconductive PES film, and more specifically means that the volume resistivity is lower than that of the PES film. Such a conductive elastic body can be obtained, for example, by mixing carbon black with rubber.

  The PES film subjected to the corona discharge treatment may be processed into a cylindrical shape after being formed into a sheet shape, but a seamless belt can be obtained by using a cylindrical shape formed from the beginning. Specifically, as the PES film, a cylindrical film extruded from an extrusion molding apparatus equipped with a circular die can be used.

  In this case, the cylindrical PES film is stretched between a pair of opposed rotating rolls facing each other, and if the electrode pair is installed so as to sandwich a part of the film in this state, the rotating roll is rotated to rotate the PES. The film can be easily slid.

Polyether sulfone (PES) _{is, [- ph-SO 2 -ph} -O -] ( although, ph represents a phenyl group) is a resin comprising a repeating structural unit represented by, does not inhibit the properties of PES It may be a copolymer containing other repeating structural units within the range. Further, for the same purpose, other thermoplastic resins and the like may be blended and used. In the present invention, these are collectively referred to as polyethersulfone (PES) resin.

  The conductive filler is not particularly limited as long as it is a filler that can be used to impart conductivity to the semiconductive belt, but carbon black, graphite, iron, copper, copper alloy, nickel, aluminum or other metals or alloys, Alternatively, fine powders of metal oxides such as tin oxide, zinc oxide, titanium oxide tin oxide-indium oxide or tin oxide-antimony oxide composite oxide are exemplified. These metals, alloys or metal oxides can be used alone or in admixture of two or more. Among them, it is preferable to use carbon black because it is inexpensive and versatile.

The semiconductive belt in the present invention has a volume resistivity (150 μm thickness) of 10 ⁶ Ω · cm to 10 ¹³ Ω used for an intermediate transfer belt or a transfer conveyance belt by blending the conductive filler. -Belts adjusted to the cm range.

  In the present invention, the PES film used for the corona discharge treatment can be used without any problem as long as it has a thickness of several tens to several hundreds of μm that is usually used as a semiconductive belt.

  In the present invention, after forming the polyethersulfone-based resin containing the conductive filler into a film shape, a voltage is applied between the discharge electrode and the counter electrode respectively installed on the front and back sides of the film. Since the corona discharge treatment is performed, it is possible to manufacture a semiconductive belt in which the voltage dependency of the electric resistance value is small and the in-plane variation of the electric resistance value is suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view schematically showing a discharge device for performing corona discharge treatment on a PES film used in the method for producing a semiconductive belt according to the present invention, and FIG. 2 is a cross-sectional view of the discharge device. is there. In the present embodiment, as the PES film 1, a cylindrical one obtained by extruding a PES resin from an extrusion molding apparatus equipped with a circular die is used.

  The discharge device includes a discharge electrode 2 and a counter electrode 3 which are arranged to face each other at a distance, a structure in which a PES film 1 is interposed between both electrodes 2 and 3 and corona discharge is performed by applying a voltage. It has become.

The counter electrode 3 is formed in a rotatable roll shape, and a conductive elastic body layer 4 made of NBR mixed with acetylene black is formed on the outer peripheral surface thereof. The volume resistivity of the conductive elastic layer 4 is set to 3.0 × 10 ⁷ Ω · cm. The thickness of the conductive elastic body layer 4 is not limited as long as the counter electrode 3 exhibits a cushioning property capable of sufficiently adhering to the PES film 1, and is usually preferably 0.3 mm to 3 mm. 0.5 mm.

  The discharge device includes a drive roll 5 that is disposed opposite to and spaced from the roll-shaped counter electrode 3, and a cylindrical PES film 1 is stretched between the counter electrode 3 and the drive roll 5, and the drive roll By rotating 5, the PES film 1 is circulated and moved. The discharge electrode 2 is disposed opposite to the counter electrode at a position slightly away from the counter electrode. As a result, the PES film 1 is in close contact with the counter electrode 3 through the conductive elastic layer 4 and is held in a state separated from the discharge electrode 2 by a certain distance.

The PES film 4 is subjected to a corona discharge treatment between the electrodes 2 and 3 while circulating and moving between the drive roll 5 and the counter electrode 3, whereby a semiconductive belt can be obtained. In order to obtain the effect of improving the electrical characteristics of the semiconductive belt, the treatment density of the discharge device is preferably 20 W · min / m ² or more. If it is less than 20 W · min / m ² , the effect of improving electrical characteristics may be reduced.

[Production of semiconductive belt]
A semiconductive belt was produced using the discharge device described in the above embodiment, and the voltage dependence of the electrical resistance value and the electrical characteristics of the in-plane variation of the electrical resistance value were evaluated. The test conditions are described below.

  First, polyethersulfone (Sumika Excel 4100P) manufactured by Sumitomo Chemical Co., Ltd. is used as the PES resin that is the raw material of the PES film, and carbon black manufactured by Denki Kagaku Kogyo Co., Ltd. as a conductive filler with respect to 100 parts by weight of the PES resin. 13 parts by weight of (acetylene black, Denka black granule) was added, and melt-kneaded and extruded by an extruder having a twin screw, and granulated into pellets.

  This pellet raw material is extruded into a cylindrical shape by an extrusion molding apparatus equipped with a circular die having a diameter of 94 mm, and is taken along a sizing mantle set to an outer diameter of 88 mm and a surface temperature of 230 ° C. A 150 μm cylindrical film was formed. A cylindrical PES film 4 having a length of 266 mm was produced from the cylindrical film.

The obtained PES film 4 was subjected to corona discharge treatment using a discharge device. As the discharge device, AGI-023 manufactured by Kasuga Electric Co., Ltd. was used, and a corona discharge treatment was performed at a belt speed of 3.3 m / min and a treatment power of 300 W (treatment density: 300 W · min / m ² ).

  The following evaluation test was performed on the semiconductive belt thus obtained (invention product). In addition, as a comparative material, the semiconductive belt produced by the same method except corona discharge treatment was used.

[Evaluation test]
(1) Voltage dependence of electrical resistance value In accordance with JIS K6911, the surface resistivity and volume resistivity of the semiconductive belt are measured at an applied voltage of 100 V, 250 V and 500 V with a resistance measuring device (R8340A manufactured by Advantest). did.

  As shown in FIGS. 3 and 4, the measurement is performed by cutting the semiconductive belt into a sheet shape and making 8 points in the TD direction (belt circumferential direction) and 4 points in the MD direction (perpendicular to the belt circumferential direction). Was taken at 32 points of each intersection, and the average value was calculated. FIG. 5 shows the result of the invention, and FIG. 6 shows the result of the comparative material.

(2) In-plane variation of electric resistance value In the same manner as described above, the surface resistivity and volume resistivity of the semiconductive belt were measured at 32 locations with an applied voltage of 500 V in accordance with JIS K6911. The results are shown in FIGS. 7 and 8 for the inventive product and FIGS. 9 and 10 for the comparative material, respectively.

[Evaluation results]
Table 1 shows log values obtained by dividing the average measured value when 100 V is applied by the average measured value when 500 V is applied with respect to the electrical dependence of the electrical resistance value. This value means that the smaller the voltage, the lower the voltage dependency.

  Table 1 shows log values obtained by dividing the maximum value of the measured values at 32 points by the minimum value for the in-plane variation of the electrical resistance value. The smaller this value is, the smaller the in-plane variation of the electric resistance value is.

  From FIG. 7, FIG. 8 and Table 1, it was found that the voltage dependency of both the surface resistivity and the volume resistivity was remarkably improved by subjecting the PES film to corona discharge treatment. 9 to 12 and Table 1, it was found that the in-plane variation of the surface resistivity and the volume resistivity is also greatly improved.

  In addition, on the conditions of the corona discharge process in a present Example, the glossiness of the PES film did not change before and after the corona discharge process, and it was confirmed that the film surface state was not changed by the corona discharge process.

The top view which shows the outline of the corona discharge apparatus used in this invention Sectional view of the device of FIG. Schematic showing a semiconductive belt Schematic showing the measurement points of the electrical resistance value of the semiconductive belt The graph which shows the voltage dependence of the electrical resistance value of the semiconductive belt obtained by this invention A graph showing the voltage dependence of the electrical resistance of the comparative material The graph which shows the dispersion | variation in the surface resistivity of the semiconductive belt obtained by this invention The graph which shows the dispersion | variation in the volume resistivity of the semiconductive belt obtained by this invention Graph showing variation in surface resistivity of comparative materials Graph showing variation in volume resistivity of comparative materials

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 PES film 2 Discharge electrode 3 Counter electrode 4 Conductive elastic body layer 5 Drive roll

Claims (3)

A method for producing a semiconductive belt comprising a polyethersulfone-based resin film containing a conductive filler, wherein the film after the polyethersulfone-based resin containing the conductive filler is formed into a film A method for producing a semiconductive belt, which is subjected to corona discharge treatment. In order to perform the corona discharge treatment, the film is interposed between the discharge electrode and the counter electrode, and further, the corona discharge is performed in a state where the counter electrode and the film are in close contact with each other through a conductive elastic layer. The method for producing a semiconductive belt according to claim 1, wherein the treatment is performed. The method for producing a semiconductive belt according to claim 1 or 2, wherein the film subjected to the corona discharge treatment is a cylindrical one extruded from an extrusion molding device equipped with a circular die.

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