JP2011138085A - Conductive bicomponent fiber and conductive brush - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive bicomponent fiber having a component containing conductive particles as a core component and a non-conductive component composed of a thermoplastic polymer as a sheath component having excellent durability for repeated use as well as being suitable for a brush used in an image forming apparatus such as a laser printer, and also to provide a conductive brush using the conductive bicomponent fiber. <P>SOLUTION: The conductive fiber composed by the core component containing the conductive substance and a sheath component composed of fiber forming polyester completely covering the core component and having fine pores on the surface satisfies following requirements. (a) The number of pores on the fiber surface is 0.1 to 1.5 pieces/μm<SP>2</SP>. (b) Single yarn fineness is 6.0 dtex or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a conductive composite fiber and a conductive brush comprising the same. More particularly, the present invention relates to a conductive composite fiber suitable for a brush used in an image forming apparatus such as a laser printer, and a conductive brush using the same, having excellent durability against repeated use.

  Thermoplastic resins such as polyethylene, polyamide, and polyester are used in many applications as fiber products, but they have the drawback of being easily charged due to their poor antistatic properties, and thus many studies on conductive fibers have been made. .

  As one of the methods, there is a method of coating the surface of the fiber with a conductive substance. The conductive fiber thus obtained has good initial conductive performance, but wear resistance when worn, and further resistance to resistance. Since the washing and chemical resistance are insufficient, there is a problem that it becomes a source of dust generation when used in dust-proof clothing.

  In addition, a method in which a conductive material powder is dispersed in a thermoplastic resin to form a core component, and a fiber-forming thermoplastic resin is coated as a sheath component to form a core-sheath forming fiber, followed by electric discharge machining at a high voltage ( For example, Japanese Patent Laid-Open No. 63-219624. In the composite fiber, when the core component is not covered with the sheath component, troubles such as fuzz in the yarn making and weaving process, wear of the yarn guides, and loss of the function due to the conductive material dropping off during use. It is the cause of the occurrence.

  Further, in the image forming apparatus, for example, a conductive brush including the conductive fiber is used as a current-carrying medium to the charging drum or the static elimination drum. In this case, the tip of the brush may make more uniform contact. Although extremely important, no method has yet been found to achieve this. Also, when these conductive fibers are used for cleaning brushes provided to remove residual toner on the photoconductor, the residual toner remains because the contact of the brush to the photoconductor is not uniform. There was a problem of getting worse.

JP-A-63-219624

  The object of the present invention is to solve the above-mentioned problems of the prior art and to provide a conductive composite fiber having high conductive performance and strength even with fineness, and an electrophotographic copying machine, printer, etc. using the conductive fiber. Another object of the present invention is to provide a conductive brush for an image forming apparatus.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have a core-sheath type composite fiber having a conductive substance as a core component, a fiber-forming thermoplastic resin as a sheath component, and having fine pores on the surface. Thus, the inventors have found that a desired conductive conjugate fiber can be obtained, and have reached the present invention.

  Thus, according to the present invention, a core component containing conductive fine particles and polyethylene terephthalate containing an alkali-soluble substance are used as a sheath component, and the alkali is reduced to form an uneven structure on the surface to improve conductivity. Even when the fineness of the single yarn is 6.0 dtex or less, a conductive composite fiber having excellent durability and image clarity is provided.

That is, according to the present invention,
A conductive fiber composed of a core component containing a conductive substance and a sheath component made of a fiber-forming polyester that completely covers the core component, and has a fine pore on the surface, and satisfies the following requirements: Conductive composite fiber, characterized by
a) The number of pores on the fiber surface is 0.1 to 1.5 / μm ² .
b) The single yarn fineness is 6.0 dtex or less.
Preferably, the fine pores are conductive composite fibers obtained by treating a core-sheath type conductive fiber having a sheath component made of polyester containing an alkali-eluting compound with an alkali solution,
As another aspect of the present invention, a conductive brush containing the conductive conjugate fiber,
Is provided.

  The conductive fiber of the present invention is a core-sheath type composite fiber, which has high strength even with fineness, and has fine pores on the surface, so that the conductivity is good, so when used in a brush, the fiber density can be increased. Therefore, it can be suitably used for an image forming apparatus such as an electrophotographic copying machine or a printer.

The cross-sectional shape of the conductive fiber of Example 1. The perspective view which shows an example of the pile fabric which comprises the electroconductive brush of this invention. The front view and side view which show an example of the cross section of the pile fabric which comprises the electroconductive brush of this invention. The side view which shows the creation example of the electroconductive brush of this invention.

  The conductive fiber of the present invention is a core-sheath type composite fiber, and the core component is made of polyester containing a conductive substance. Preferred examples of the polyester that can be used include polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate.

As the conductive substance, known substances such as conductive carbon black and conductive metal compounds can be used.
Examples of the conductive carbon black include oil furnace type “Ketjen Black EC” (manufactured by Japan EC), “Conductex 975”, “Conductex SC” (Colombian) and acetylene type “DENKA”. In addition to known conductive carbon black such as “Black” (manufactured by Denka), thermal black, channel black, ketjen black and the like can be used.

  On the other hand, as the conductive metal compound, metal particles, metal oxide or metal compound particles, or particles having these films can be used. Examples of the metal particles include silver, nickel, copper, iron, aluminum, and alloys thereof. Particles having a metal oxide or metal oxide film include tin oxide obtained by mixing and firing antimony oxide as a second component, zinc oxide containing aluminum oxide as a second component, and conductivity such as tin oxide and zinc oxide. Inorganic particles such as titanium oxide, magnesium oxide, silicon oxide, and aluminum oxide having an oxide film can be used. As the metal oxide, copper iodide, copper sulfide, zinc sulfide, cadmium sulfide, or the like can be used. Among these, stannic oxide and zinc oxide excellent in whiteness are preferably exemplified. The stannic oxide here includes stannic oxide containing a small amount of an antimony compound, and conductive metal composites in which the surface of titanium oxide particles is coated with stannic oxide. Zinc oxide also includes zinc oxide containing a small amount of aluminum oxide, lithium oxide, indium oxide, and the like. These conductive materials are usually used as fine powder dispersed in a matrix polymer.

  The blending ratio of these conductive substances varies depending on the kind of particles, the particle diameter, the conductivity, and the properties and crystallinity of the matrix polymer, but is usually preferably 15 to 80% by weight based on the total weight of the matrix polymer. When the blending amount is less than 15%, the electrical conductivity is lowered, and when it exceeds 80%, uniform dispersion in the polymer becomes difficult and the spinning property is also lowered.

On the other hand, the polymer used as the sheath component is preferably polyester, polyolefin, or a copolymer thereof, and particularly preferably polyethylene terephthalate.
In addition, organic sulfonic acid or its metal salt, organic phosphoric acid or its metal salt, etc., and alkali-soluble compounds such as polyalkylene glycol, block polyether ester, block polyether amide, etc. It is preferable to disperse 5% or less. The blending amount of the alkali-soluble compound is preferably 0.5 to 4.0%, more preferably 0.5 to 3.0%. If it is less than 0.5%, it is difficult to form micropores, and if it exceeds 5%, the fiber strength is undesirably lowered.

The cross-sectional shape of the conductive conjugate fiber of the present invention is not particularly limited, but those having a cross-sectional shape having sharp protrusions are preferable from the viewpoint of high conductivity, as illustrated in FIG.
In the composite fiber cross section, the area occupied by the core component is preferably 5 to 30%. When the area is smaller than 5%, the antistatic property may be inferior. On the other hand, when the area exceeds 30%, the mechanical properties, dust resistance, and durability of the fiber may be deteriorated.

  It is preferable that the conductive composite fiber obtained as described above is woven and knitted by a known method to form a fabric, and fine pores are formed on the fiber surface by eluting the alkali-soluble compound with a known alkali weight loss device.

  Examples of the alkali compound used here include sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, sodium carbonate, potassium carbonate and the like. Of these, sodium hydroxide and potassium hydroxide are particularly preferred.

  The concentration of the aqueous solution of the alkali compound varies depending on the type of alkali compound, processing conditions, and the like, but is usually preferably in the range of 0.01 to 40% by weight, particularly preferably in the range of 0.1 to 30% by weight. The treatment temperature is preferably from room temperature to 100 ° C., and the treatment time is usually from 1 minute to 4 hours. Further, the amount of elution and removal by treatment with the aqueous solution of the alkali compound should be in the range of 2% by weight or more based on the fiber weight.

Thus, by processing with the aqueous solution of an alkali compound, 0.1-1.5 micro-micrometer < ² > micropores are formed in the fiber surface. By having these micropores, the conductivity is greatly improved and the fiber strength is maintained. If it is less than 0.1 unit / μm ² , the conductivity is insufficient, and if it exceeds 1.5 unit / μm ² , the strength decreases, which is not preferable.
The conductive conjugate fiber of the present invention includes optional additives such as a catalyst, an anti-coloring agent, a heat-resistant agent, a flame retardant, a fluorescent whitening agent, a matting agent, and a coloring agent as necessary. It may be.

  The conductive conjugate fiber of the present invention uses a conventionally known composite spinning device, and uses the polyester containing the alkali-soluble substance described above on the sheath side and the polyester containing the conductive substance in the core, and has a viscosity of 2000 to 4500 m / It is possible to obtain a product obtained by melt spinning at a speed of min., Preferably 2000 to 3000 m / min, and stretching to reduce the alkali. It is preferable to obtain it by knitting and weaving into a fabric and reducing the alkali weight.

  In order to produce a conductive brush according to another aspect of the present invention, first, a pile fabric made of pile yarn containing the fibers is produced. As a manufacturing method of a pile fabric, it can manufacture using a publicly known method. For example, in the case of a pile woven fabric, a fabric such as a moquette / velvet shown in FIG. 2 can be manufactured by a known method. In this case, the conductive conjugate fiber may be used only at least for the pile yarn. On the other hand, in the case of a pile knitted fabric, a fabric such as a double raschel tricot can be produced by a known method. In addition, when manufacturing a pile fabric, 2 or more types of fibers can also be used together, for example, in the range which does not impair the performance of a conductive brush, normal polyester fiber is added to the conductive composite fiber of this invention. A pile fabric may be manufactured.

  2 to 4 show an example of a conductive brush using the conductive conjugate fiber of the present invention, FIG. 2 is a perspective view showing an example of a pile fabric constituting the conductive brush, and FIG. 3 shows a conductive brush. FIG. 4 is a side view showing an example of a conductive brush according to the present invention. FIG. In FIG. 3, 1 is a warp yarn of the pile fabric, 2 is a weft yarn, 3 is a base fabric, 4 is a coating layer applied as needed, and 5 is a pile yarn. Moreover, 6 in FIG. 4 shows a pile fabric, 7 shows a support | pillar.

  In order to manufacture the conductive brush of the present invention, for example, as shown in FIG. 3, the pile fabric produced by the above method is spirally wound around a column to form a brush shape. Thereafter, napping treatment and shearing treatment are performed to obtain a conductive brush for an image forming apparatus. Moreover, it is good also as an electroconductive brush which fixed the pile fabric to the plane.

The cross-sectional electrical resistance value (temperature 20 ° C., humidity 40 to 70% RH) of the conductive composite fiber in the conductive brush is preferably 10 ² to 10 ¹¹ Ω / cm. Preferably, a temperature of 25 ° C. and a humidity of 40% RH is 10 ³ to 10 ¹⁰ Ω / cm. Although it differs depending on the type of image forming apparatus, it is not preferable because it is difficult to obtain uniform charging, static elimination, and cleaning effects even if it is lower or higher.

  Since the pile yarn made of the conductive conjugate fiber of the present invention satisfies the above conditions, it exhibits a sufficient function as a conductive brush that can be suitably used for an image forming apparatus such as a laser printer.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these Examples. In addition, the physical property and determination of the microporous fiber shown in an Example and a comparative example are measured with the following method.

(1) Inter-section internal electrical resistance value Ag doutite (silver particle-containing conductive resin paint, manufactured by Fujikura Kogyo Co., Ltd.) on both cross-sections of the fiber cut at both ends in the cross-sectional direction so that the length in the fiber axis direction is 10 cm. On the electrically insulating polyethylene terephthalate film, a DC voltage of 1.7 kV was applied using the Ag doubite-attached surface on the electrically insulating polyethylene terephthalate film under the conditions of a temperature of 25 ° C. and a relative humidity of 40%. The current value was determined, and the electrical resistance value Ω / cm was calculated according to Ohm's law.

(2) Durability of the conductive brush JIS L1096 8.17.3 In the friction strength test of the C method (taper criminal method), the load was 4.90 N and the wear ring No. The wear durability of the conductive brush was measured with CS-17 and 500 frictions.
○: Good ×: Bad

(3) Average pore diameter The pore size was measured by a mercury intrusion porosimeter method using a pore sizer 9310 manufactured by Shimadzu Corporation.

(4) Number of holes The number of holes was measured using Micro Hiscope System DH-2200 manufactured by Hilox Corporation.

(5) Image evaluation method In the brush charging method, the charged image output test is performed by applying a DC bias voltage with the brush rotation direction opposite to the photoconductor, and the image evaluation after 10,000 copies is based on the following criteria: went.
A: A clear and uniform image similar to the initial one can be obtained.
Δ: Slightly abnormal discharge traces are observed.
X: The image is unclear and streaks are conspicuous.

[Example 1]
Conductive resin composition comprising 27.0 parts by weight of conductive carbon black and 73.0 parts by weight of polyethylene terephthalate having an intrinsic viscosity of 0.64 as a core component and 3,5- (dicarbomethoxy) benzene as an alkali-soluble compound Using a polyethylene terephthalate containing 2.4% by weight of sodium sulfonate as a sheath component, a core-sheath type composite fiber having a cross-sectional shape shown in FIG. 1 is spun at a spinning speed of 2500 m / min by melt spinning and then drawn. And heat set to obtain a 250 dtex / 40 fil multifilament yarn.
Next, a pile fabric (velvet) using this fiber as a pile yarn was manufactured, and a conductive brush was prepared. At this time, the pile fabric was designed to have a pile density of 5,000 pieces / cm ² and a pile length of 5 mm. A test piece in which a polyester fiber sample was formed on a fabric was immersed in an aqueous sodium hydroxide solution having a concentration of 10 g / L at a bath ratio of 30 and subjected to an alkali weight reduction treatment until a weight loss rate of 10% was obtained. This brush exhibited excellent durability and image clarity. The results are shown in Table 1.

[Example 2-3]
In Example 1, the same procedure as in Example 1 was carried out except that multifilament yarns having drawn filaments of 250 dtex / 60 fil and 250 dtex / 80 fil were obtained. These also showed excellent durability and image clarity. The results are shown in Table 1.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that the sheath polymer was polyethylene terephthalate not containing sodium 3,5- (dicarbomethoxy) benzenesulfonate. In this case, there was no hole in the surface after the alkali reduction, resulting in a lack of image clarity. The results are shown in Table 1.

[Comparative Example 2]
In Example 1, the same procedure as in Example 1 was performed except that a multifilament yarn having a stretched filament of 250 dtex / 20 fil was obtained. In this case, the fineness of the single yarn was increased and the fiber density was insufficient, resulting in lack of image clarity. The results are shown in Table 1.

[Comparative Example 3]
In Example 1, it implemented like Example 1 except the weight loss rate being 20%. In this case, the number of holes increased and the hole area also increased, resulting in a lack of brush durability. The results are shown in Table 1.

  According to the present invention, since the surface has a micro uneven structure, a clear and uniform image similar to the initial stage can be obtained for repeated use, and it has excellent durability. It can be suitably used for an image forming apparatus such as a printer.

1 Warp Thread 2 Horizontal Thread 3 Base Cloth 4 Coating Layer 5 Pile Thread 6 Pile Cloth 7 Strut

Claims (3)

A conductive fiber composed of a core component containing a conductive substance and a sheath component made of a fiber-forming polyester that completely covers the core component, and has a fine pore on the surface, and satisfies the following requirements: Conductive conjugate fiber characterized by
a) The number of pores on the fiber surface is 0.1 to 1.5 / μm ² .
b) The single yarn fineness is 6.0 dtex or less.   The conductive composite fiber according to claim 1, wherein the fine pores are obtained by treating a core-sheath type conductive fiber having a sheath component of polyester containing an alkali-eluting compound with an alkaline solution.   The electroconductive brush containing the electroconductive composite fiber of Claims 1-2.

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