JP2011126145A - Method for manufacturing conductive molded object, and conductive molded object obtained thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a conductive molded object, capable of enhancing surface resistivity without increasing the amount of a conductive material. <P>SOLUTION: The surface resistivity of the conductive molded object can be enhanced by containing a process for stretching an extruded molded object in a draw ratio of twice or above in a manufacturing method performing the extrusion molding of a conductive molded object material. Further, the conductive molded object can be manufactured using more inexpensive thermoplastic resin and even a tubular conductive molded object can be easily manufactured by extrusion molding. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a conductive molded body. In more detail, this invention relates to the manufacturing method of the electroconductive molded object which can enlarge the surface resistivity of an electroconductive molded object, without making the addition amount of an electroconductive material increase.

  The semiconductive intermediate transfer belt is one of members constituting an intermediate transfer system of a copying machine and is widely used. As an example of a semiconductive belt that can be used for such an intermediate transfer belt, an intermediate transfer belt is proposed in which carbon black such as acetylene black is dispersed as a conductive filler in a polyimide resin (Patent Document 1). . When a polyimide-based material is used, the price of the product itself is expensive, so a lower price product is required.

  In addition, a conductive material is added to the semiconductive intermediate transfer belt in order to impart semiconductivity. However, with the increase in the amount of conductive material added, there is a problem that the mechanical properties and the like of the resulting film are poor.

JP-A-63-311263

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a conductive molded body capable of increasing the surface resistivity without increasing the amount of conductive material added. It is to provide a manufacturing method.

The manufacturing method of the electroconductive molded object of this invention is a manufacturing method of the electroconductive molded object which extrude-forms an electroconductive molded object material, Comprising: The process of extending | stretching the extruded molded object by 2 times or more of draw ratio is included.
In a preferred embodiment, the conductive molded body is tubular.
In preferable embodiment, the said electroconductive molded object contains a thermoplastic resin.
In a preferred embodiment, the conductive molding material includes an alloy of two or more resins having different glass transition temperatures.
According to another aspect of the present invention, a conductive molded body is provided. This electroconductive molded object is obtained by the manufacturing method of said electroconductive molded object.
In a preferred embodiment, the conductive molded body is a conductive intermediate transfer belt.
According to another aspect of the present invention, an image forming apparatus is provided. This image forming apparatus uses the above-described conductive intermediate transfer belt.

  According to the production method of the present invention, the surface resistivity of the conductive molded body can be increased without increasing the amount of the conductive material added by stretching the extruded product at a stretch ratio of 2 times or more. . Furthermore, according to the manufacturing method of the present invention, a cheaper thermoplastic resin can be used, and a tubular conductive molded body can be easily manufactured by extrusion molding.

It is a schematic diagram which shows the concept of the manufacturing method of the electroconductive molded object in preferable embodiment of this invention. It is explanatory drawing which shows the measurement position of the thickness distribution of the molded article in the Example of this invention. It is explanatory drawing which shows the measurement position of the thickness of a molded article and the surface resistivity in the Example of this invention.

<A. Conductive molding material>
The conductive molding material includes a resin component constituting the molding and a conductive material. The resin component is preferably a polymer alloy obtained by alloying two or more resins having different glass transition temperatures. By using the polymer alloy, it is possible to obtain a composition in which the conductive material is ubiquitously dispersed in one resin, and the conductive material is highly dispersed. Can be obtained. Furthermore, the mechanical properties of the obtained film can be improved by reducing the addition amount of the conductive material.

  Any appropriate thermoplastic resin can be used as the resin component contained in the conductive molding material. Specifically, polyethylene resins such as high, medium and low density polyethylene, linear low density polyethylene, polypropylene resin, poly-1,2-butadiene resin, ethylene-butene copolymer, ethylene-vinyl acetate copolymer A polyolefin resin such as a copolymer of ethylene and methyl-, ethyl-, propyl-, or butyl-acrylate or methacrylate, or a chlorinated product thereof, or a mixture of two or more thereof; polystyrene resin, Styrenic resins such as ABS resin and AS resin; Polyphthalate resins such as polyethylene phthalate resin and polybutylene terephthalate resin; Polyamide resins such as 6-nylon resin and 6,6-nylon resin; Polysulfone resin, modified polysulfone resin, Polyallyl sulfone resin, poly Ton resin, polyetherimide resin, polyarylate resin, polyphenylene sulfide resin, liquid crystal polymer, polyethersulfone resin; polyetheretherketone resin, polyimide resin, polyamideimide resin, fluororesin super engineering resin; polyvinyl chloride resin , A thermoplastic urethane resin, a polyacetal resin, a polycarbonate resin, a modified polyphenylene ether resin, or a mixture of two or more thereof. Among these, it is preferable to use a polycarbonate resin. In the present specification, the thermoplastic resin is also referred to as a base resin.

  The other resin to be alloyed with the thermoplastic resin (hereinafter referred to as alloying resin) is not particularly limited as long as it has a glass transition temperature lower than that of the thermoplastic resin. By alloying a resin having a glass transition temperature lower than that of the thermoplastic resin, the conductive material can be unevenly distributed in the resin layer having a low glass transition temperature, and the conductive material can be further dispersed. Preferably, a polyester resin is used.

  When a polymer alloy is used as the resin component, the alloying resin is preferably used in an amount of 1 to 20 parts by weight, more preferably 5 to 20 parts by weight, based on 100 parts by weight of the base resin.

  As the conductive material, any appropriate material can be used. For example, various carbon, aluminum, nickel, tin oxide, an inorganic compound such as potassium titanate, or a conductive polymer such as polyaniline or polypyrrole can be used. it can. Of these, carbon black is preferably used. As characteristics of carbon black, those having a DBP oil absorption of 100 ml / 100 g or more, more preferably 150 to 700 ml / 100 g are preferred. Examples of such carbon blacks are those commercially available as conductive carbon blacks (such as Lion Ketjen Black EC, Cabot Vulcan XC-72, Denki Kagaku Denka Black), and others, naphtha, etc. And carbon black produced as a by-product when producing a synthesis gas containing hydrogen and carbon monoxide by partially oxidizing the hydrocarbons in the presence of hydrogen and oxygen, or carbon black obtained by oxidizing or reducing this.

  The blending ratio (parts by weight) of the conductive material and the resin component is preferably 10:90 to 60:40, and more preferably 20:80 to 50:50. If the conductive material exceeds 60 parts by weight and the resin component is less than 40 parts by weight, it becomes difficult to knead them, and there is a possibility that aggregates of the conductive material are generated. If the conductive material is less than 10 parts by weight and the resin component exceeds 90 parts by weight, the conductivity may be insufficient.

  A commercially available product may be used as the conductive molding material. For example, FED03, FED05, etc. of Leo Pound series (manufactured by Lion Corporation) are preferably used.

  Moreover, it is good also considering the said commercial item as a masterbatch, and also adding a dispersion | distribution auxiliary resin to be an electroconductive molded material. Any appropriate resin can be used as the dispersion auxiliary resin. Preferably, the dispersion auxiliary resin is a resin having a higher viscosity than the master batch. By using a dispersion auxiliary resin having a higher viscosity than that of the master batch, the conductive material can be further highly dispersed without substantially destroying the connection structure between the conductive materials exhibiting conductivity. Moreover, by including a dispersion auxiliary resin having a high viscosity, the surface resistance can be increased at a lower draw ratio, and the conductivity can be maintained even at a higher draw ratio. As the dispersion auxiliary resin, the thermoplastic resins exemplified above can be used. Preferably, the dispersion auxiliary resin is the same resin as the resin component when the resin component contained in the masterbatch is a single resin, and when the resin component contained in the masterbatch is a polymer alloy. Of the resins contained in the polymer alloy, the same resin as the base resin. The blending ratio (weight) of all resin components and dispersion auxiliary resin contained in the master batch is preferably 10:90 to 50:50.

  The melt viscosity of the conductive molded material is preferably 1 to 200 g / 10 min in terms of melt flow rate (based on JIS K-7210). By having such melt viscosity, extrusion molding can be easily performed by the production method of the present invention.

<B. Method for producing conductive molded body>
An example of the manufacturing method of an electroconductive molded object is demonstrated with reference to FIG. FIG. 1 is a schematic view showing the concept of a method for producing a conductive molded body in a preferred embodiment of the present invention. In the example shown in FIG. 1, the conductive molded body is formed by extruding a conductive molded body material by the extruder 100 and the dies 151 and 152, and the extruded molded product is drawn while being stretched by the take-up machine 400. Manufactured by. The conductive molding material is charged from the hopper 101 and melt-kneaded in the barrels 111, 112, 113, and 114. A certain amount of the molten conductive molding material is pushed out to the dies 151 and 152 via the head 120 by the gear pump 130. The extruded conductive material in the molten state is formed into a desired shape through dies 151 and 152. The barrels 111, 112, 113, 114, the head 120, and the dies 151, 152 are set to a temperature at which the resin component contained in the conductive molding material used is melted by the heat medium circulating device 140. The extruded molded body 200 is drawn by the take-up machine 400 via the rolls 301 and 302, so that the drawing process is performed. In the stretching treatment, the stretch ratio can be increased to 2 or more by pulling the molded body 200 at an appropriate take-up speed. The extruder is not particularly limited, and may be a single-screw extruder or a multi-screw extruder such as a twin-screw extruder.

  Examples of the method for charging the conductive molded material include, for example, a method in which pellets obtained by premixing a resin component and a conductive material, or a master batch and a dispersion auxiliary resin are collectively charged with a feeder, and a material used as a conductive molded material. There is a method of preparing as many feeders as possible and feeding them at the same time. By introducing the conductive molded material by such a method, a sheet with little variation in the longitudinal direction can be produced. In the case of using a masterbatch and a dispersion auxiliary resin as the conductive molding material, the masterbatch may be charged after the dispersion auxiliary resin is charged. By adding in this order, the dispersion auxiliary resin and the master batch can be mixed more uniformly.

  In another embodiment, an extruder having a vent port (not shown) is used. By using an extruder having a vent port, the surface smoothness of the obtained conductive molded body can be improved. The vent port may further include a suction mechanism (not shown) such as a vacuum pump or a decompression device. When venting is performed using the suction mechanism, the same effect as that obtained when the suction mechanism is used can be obtained by opening the vent port to the atmosphere.

  What is necessary is just to set the temperature of the said barrel, a head, and die | dye to the temperature which the resin component contained in an electroconductive molded object material fuse | melts. In the case of using a conductive molding material containing two or more kinds of resins as resin components, it is preferable that the temperature is such that all the resins are melted and mixed and melted.

  The die is not particularly limited and can be selected according to the shape of the molded product. When manufacturing a tubular molded product, a spiral die is preferably used. By using a spiral die, a tubular conductive molded body excellent in resistance uniformity and film thickness uniformity can be obtained. A spiral die having a large number of spiral stripes is preferable from the viewpoint of improving the balance of inflow of the conductive molded material from the extruder to the die and improving the film thickness and conductivity uniformity.

  In the production method of the present invention, the surface resistivity of the conductive molded body can be increased by stretching the molded product at a stretching ratio of 2 or more in the stretching step. The draw ratio may be 2 times or more, preferably 2 to 13 times. The draw ratio may be appropriately selected according to the presence / absence of the use of the dispersion auxiliary resin and the desired surface resistivity.

  The stretching step may be performed continuously with extrusion as illustrated in FIG. 1 or may be performed as a separate process from extrusion. The stretching direction of the molded product may be the longitudinal direction (the length direction of the molded product) or the lateral direction (the width direction of the film-shaped molded product, the circumferential direction of the tubular molded product). You may extend | stretch.

  Manufacturing efficiency improves by performing the said extending process continuously with extrusion molding. When the stretching process is performed continuously with the extrusion molding, the stretching process can be performed by taking out the molded product extruded from the die at an appropriate speed. The draw ratio can be determined by setting the ratio between the die extrusion speed and the take-up speed. When the stretching step is performed continuously with extrusion, the stretching direction is preferably the longitudinal direction.

  When performing the said extending process as a process separate from extrusion molding, extending | stretching of a film can be performed by arbitrary appropriate methods. For example, a free end longitudinal stretching method uniaxially stretching in the longitudinal direction, a fixed end lateral stretching method uniaxially stretching in the width direction with the longitudinal direction of the film fixed, and sequential or simultaneous two performing stretching in both the longitudinal direction and the width direction. An axial stretching method, a method of stretching in the width direction and contracting in the longitudinal direction can be used.

The present invention will be further described using the following examples and comparative examples. The present invention is not limited only to these examples. The analysis methods used in the examples are as follows.
(1) Measuring method of surface resistivity:
The surface resistance value was measured for 10 seconds at an applied voltage of 100 V, 250 V, 500 V, and 1000 V using Hiresta UP MCP-HT450 (manufactured by Mitsubishi Chemical Analytech Co., Ltd., probe: URS). When the applied voltage is 100 V and 250 V, the value cannot be detected when the surface resistivity is 10 ⁵ Ω / □ or less, and when the surface resistivity is 10 ¹³ Ω / □ or more, so under (10 ⁵ Ω / □ or less) or over (10 ¹³ Ω / □ or more). When the applied voltage is 500 V, the value cannot be detected when the surface resistivity is 10 ⁶ Ω / □ or less and 10 ¹⁴ Ω / □ or more. Therefore, under (10 ⁶ Ω / □ or less) or over (10 ¹⁴ Ω / □ or more). When the applied voltage is 1000 V, the value cannot be detected when the surface resistivity is 10 ⁷ Ω / □ or less, and when the surface resistivity is 10 ¹⁵ Ω / □ or more. Therefore, under (10 ⁷ Ω / □ or less) or over (10 ¹⁵ Ω / □ or more).

Example 1: Continuous film forming test [Examples 1-1 to 1-5]
Commercially available conductive molding materials (Lion Corporation, trade name “Leopound FED03”, polycarbonate and polyester resin alloy dispersed with ketjen black), and dispersion auxiliary resin (made by Idemitsu Kosan, trade name “ Toughlon # 2600 ”, polycarbonate resin) was pre-dried at 120 ° C. for 24 hours.
Dispersion auxiliary resin and commercially available conductive molding material were added to a twin screw kneading extruder (manufactured by Toyo Seiki Seisakusho Co., Ltd., twin screw kneading extruder “2D30W2”, basic specification: Table 1) using two feeders. At the same time, the film was kneaded and molded, and the resulting molded product was drawn with a roll while being stretched to obtain a stretched film. Table 2 shows kneading conditions, film forming conditions, discharge pressure, torque, thickness of the obtained film, and the like. The feed rotation speed was determined by creating a calibration curve of the screw rotation speed and the discharge amount.

[Examples 1-6 to 1-8]
A commercially available polymer alloy (trade name “P-5001” manufactured by Unitika Ltd., alloy of polyarylate and polycarbonate (50/50)) and carbon black (manufactured by Degussa, channel black “SB4”) are mixed with a twin-screw kneader. Pellets were obtained by kneading and pelletizing with (made by Nagata Manufacturing Co., Ltd., basic specification: Table 3).
20 parts by weight of the above pellets are put into a biaxial kneading extruder (manufactured by Toyo Seiki Seisakusho, biaxial kneading extruder “2D30W2”, basic specification: Table 1), kneaded and molded, and the resulting molded product is obtained. The film which extended | stretched was obtained by taking up with a roll, extending | stretching. Table 4 shows kneading conditions, film forming conditions, discharge pressure, torque, thickness of the obtained film, and the like. The feed rotation speed was determined by creating a calibration curve of the screw rotation speed and the discharge amount.

  The films of Examples 1-1 to 1-8 were cut at 20 cm to obtain test pieces (20 cm × 15 cm). The predetermined four portions of this test piece were measured at positions 1 to 4, and the thickness and the surface resistance value were measured. Moreover, the draw ratio was calculated from the thickness of the obtained film and the die lip of the extruder. The evaluation results are shown in Table 5.

[Comparative Example 1]
A commercially available conductive molding material (manufactured by Lion Corporation, trade name “Leopound FED03”) was heat-pressed at a temperature of 300 ° C. and a pressure of 10 MPa for 2 minutes to form a film. The evaluation results of the thickness and surface resistivity of the obtained film are shown in Table 6 together with the results of Comparative Examples 2-1 to 2-3 described later.

Comparative Example 2: High shear batch test [Comparative Example 2-1]
Commercially available conductive molded material (Lion Corporation, trade name “Leopound FED03”) and dispersion auxiliary resin (Idemitsu Kosan, trade name “Taflon # 2600”, polycarbonate resin) are at 65 ° C. for 6 hours or more and 65 cmHg. Preliminary vacuum drying was performed under the following conditions.
30 g of a high shear kneading machine (manufactured by Imoto Seisakusho Co., Ltd., HSE3000mini, basic specification: Table 7) mixed with a commercially available conductive molding material and a dispersion auxiliary resin in a 1: 9 ratio (hereinafter referred to as Formulation A) 30 g Was discharged and the inside was discharged. Next, the discharge from the die was stopped, 6 g of the blend A was charged and circulated in the machine. 30 g of a mixture (hereinafter referred to as “blend B”) in which a commercially available conductive molding material and a dispersion auxiliary resin are mixed at a ratio of 1: 9 is charged, the blend A is discharged, and a sample is obtained. Replaced. The obtained sample was hot-pressed at a temperature of 280 ° C. and a pressure of 10 MPa for 2 minutes to obtain a film. Table 8 shows the kneading conditions. Table 9 shows the resin temperature and torque data during kneading of the obtained sample, and Table 6 shows the evaluation results of the thickness and surface resistivity of the obtained film.

[Comparative Example 2-2]
A sample was obtained in the same manner as in Comparative Example 2-1, except that the mixing ratio of the commercially available conductive molding material and the dispersion auxiliary resin was set to 2: 8. Table 9 shows the resin temperature and torque data during kneading of the obtained sample, and Table 6 shows the thickness and surface resistivity of the obtained film.

[Comparative Example 2-3]
A sample was obtained in the same manner as in Comparative Example 2-1, except that the mixing ratio of the commercially available conductive molding material and the dispersion auxiliary resin was 5: 5. Table 9 shows the resin temperature and torque data during kneading of the obtained sample, and Table 6 shows the evaluation results of the thickness and surface resistivity of the obtained film.

Example 2: Continuous tubular molding test [Example 2-1]
A commercially available conductive molding material (manufactured by Lion, trade name “Leopound FED03”) was preliminarily dried at 120 ° C. for 6 hours. A tubular molded body was manufactured using a single screw extruder (GT40-32-A, manufactured by Plastic Engineering Laboratory Co., Ltd., basic specification: Table 10) and an annular extrusion die in which a flow path was formed in a spiral shape. . Table 11 shows the setting conditions of the single screw extruder and the conditions when an actual film was obtained. The take-up speed was adjusted so that the average thickness of the film after taking was 100 μm. In addition, although vacuuming was performed from the vent port, since the venting was performed, the atmosphere was released to the atmosphere without reducing the pressure.

[Example 2-2]
A tubular molded body was produced in the same manner as in Example 2-1, except that the polymer alloy / carbon black pellets used in Examples 1-6 to 1-8 were used as the conductive molded body material. Table 11 shows the conditions set by the single-screw extruder and the conditions when an actual film was obtained.

  The tubular molded body obtained in Example 2-1 was cut out by 50 cm, and at the measurement positions 1 to 8 shown in FIG. 2, three points at both ends (a, c) and the center (b, 25 cm from the end) Then, each thickness was measured. Table 12 shows the thickness at each measurement position.

  The tubular molded bodies obtained in Examples 2-1 and 2-2 were cut into 50 cm and used as samples. About the measurement positions 1-6 shown in FIG. 3 of each sample, the surface resistivity and thickness of the sample surface and the back surface were measured. The sample surface is the surface of the tubular molded body, and the back surface is the surface in contact with the inner core surface. These were measured at both ends of the sample (a and c in FIG. 3). The measurement results are shown in Table 13 for Example 2-1 and in Table 14 for Example 2-2.

[Evaluation]
In Examples 1-1 to 1-8, the surface resistivity of almost all Examples was 10 ¹³ Ω / □ or more. On the other hand, in Comparative Examples 2-1 to 2-3 in which a film is formed by hot pressing (a polycarbonate resin is used as a commercially available conductive molding material and a dispersion auxiliary resin), Comparative Example 2- in which the ratio of the dispersion auxiliary resin is large. Except for 1, the surface resistivity was under for most applied voltages. By subjecting the film to a stretching treatment so that the stretching ratio is 2 times or more, the surface resistivity of the molded product was significantly increased. When a conductive molded material containing a commercially available polymer alloy (P-5001 manufactured by Unitika Ltd.) and carbon black (Degussa, SB4) is formed into a press film, it is usually 10 ¹¹ Ω / □ at 100 V. On the order of 1000 V, the surface resistivity is 10 ¹⁰ Ω / □. Even when a commercially available polymer alloy and carbon black were used as the conductive molding material, the surface resistivity was remarkably increased by subjecting the film to stretching so that the stretching ratio was 2 times or more.

  In Examples 2-1 and 2-2, a tubular molded body could be formed by extrusion molding. The variation in thickness of the tubular molded body was about ± 15%. In Example 2-1, the surface of the obtained tubular molded body was smooth and glossy, but the tubular molded body obtained in Example 2-2 was compared with the tubular molded body of Example 2-1. Many aggregates were confirmed on the surface.

In Comparative Example 1, which is a film obtained by hot pressing a commercially available conductive molding material (trade name “Leopound FED03”, manufactured by Lion Corporation), the surface resistivity was under when 100 V and 250 V were applied. The surface resistivity of the tubular molded body of 2-1 when applying 100 V and 250 V was 8.54 × 10 ^{6 to} 2.07 × 10 ⁹ Ω / □, and the value increased. In a film obtained by hot pressing a conductive molding material containing a commercially available polymer alloy (P-5001 made by Unitika Ltd.) and carbon black (Degussa, SB4), the surface resistivity when applying 100 V is usually 10 The surface resistivity at the order of ¹¹ Ω / □ and 1000 V applied was 10 ¹⁰ Ω / □, but the surface resistivity of the tubular molded body of Example 2-2 was all over. From these results, even in the case of producing a tubular molded body, by stretching the extruded product moderately (7.5 to 12.3 times in Examples 2-1 and 2-2), It can be seen that the surface resistivity can be increased.

  Moreover, it can be seen from the results of Table 12 that the surface resistivity of the back surface of the tubular molded body is higher than the surface resistivity of the surface of the tubular molded body. Since the back surface of the tubular molded body is in contact with the inner core, the cooling rate is higher than that of the surface of the tubular molded body in contact with the air, and thus the surface resistivity is considered to be increased.

  The electroconductive molded object of this invention can be used suitably for the use as which electroconductivity is requested | required. The conductive intermediate transfer belt using the conductive molded body of the present invention can be suitably used for an image forming apparatus such as a printer or a copying machine.

DESCRIPTION OF SYMBOLS 100 Extruder 101 Hopper 111,112,113,114 Barrel 120 Head 130 Gear pump 140 Heat-medium circulation apparatus 151,152 Die 200 Conductive molding 301,302 Roller 400 Take-up machine

Claims (7)

A method for producing a conductive molded body by extruding a conductive molded body material,
The manufacturing method of an electroconductive molded object including the process of extending | stretching the extruded molded object by 2 times or more of draw ratios.   The manufacturing method of the electroconductive molded object of Claim 1 whose said electroconductive molded object is tubular.   The manufacturing method of the electroconductive molded object of Claim 1 or 2 with which the said electroconductive molded object contains a thermoplastic resin.   The manufacturing method of the electroconductive molded object in any one of Claim 1 to 3 in which the said electroconductive molded object material contains the alloy of 2 or more types of resin from which a glass transition temperature differs.   The electroconductive molded object obtained by the manufacturing method of the electroconductive molded object in any one of Claim 1 to 4.   The electroconductive molded object of Claim 5 used as an electroconductive intermediate transfer belt.   An image forming apparatus using the conductive intermediate transfer belt according to claim 6.

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