JP2006293109A - Conductive brush - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive brush which is excellent in durability, is reduced in the variation of an electric resistance value, and is suitably used for an image forming apparatus, especially. <P>SOLUTION: The conductive brush is composed of pile fabric having a pile yarn napped or bristled on the surface of foundation, and the pile yarn is composed of conductive polyester fiber containing polyoxyalkylene glycol which does not have reactivity substantially with polyester, and ionic antistatic agent by 5 to 15 wt.%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a conductive brush. More specifically, a brush used in an image forming apparatus such as a laser printer, for example, a static elimination brush for neutralizing the photosensitive drum surface after image transfer, a charging brush for charging the photosensitive drum surface, and residual toner on the photosensitive member. The present invention relates to a conductive brush suitable as a cleaning brush for removal.

  As fibers for brushes used in electrophotographic recording type dry copying machines, facsimiles, printers, and the like, as disclosed in Patent Documents 1 to 4, vinylon conductive yarns or nylons containing cellulosic fibers or conductive carbon are used. Conductive yarn or polyester conductive yarn is used.

  However, cellulosic fibers, vinylon fibers, and nylon fibers have poor mechanical strength, particularly durability, and are formed when used as conductive brushes such as static elimination brushes, charging brushes, or cleaning brushes in image forming apparatuses such as laser printers. There is a problem that the quality of the generated image is degraded.

  On the other hand, in the polyester conductive yarn and nylon conductive yarn kneaded with conductive carbon, it is difficult to uniformly disperse the carbon particles in the fiber in the raw yarn manufacturing stage, and the variation in the electric resistance value of the conductive yarn is large. When used as a conductive brush for the image forming apparatus, there is a problem that the formed image varies from product to product.

JP-A-9-491117 JP 2000-355823 A JP 2000-160427 A JP 2003-66669 A

  The present invention has been made against the background of the above-described prior art, and it is an object of the present invention to provide a conductive brush that is excellent in durability and has little variation in electric resistance value, and can be suitably used particularly for an image forming apparatus.

  When the present inventor uses a polyester fiber containing a specific compound as a fiber constituting the pile yarn in order to solve the above-mentioned problems, it has excellent durability and there is little variation in the electric resistance value. It has been found that high quality images can be obtained when used as a conductive brush in the device.

  That is, according to the present invention, a pile fabric having pile yarns raised or raised on the surface of a base fabric, the pile yarns having substantially no reactivity with polyester and ionic charging A conductive brush comprising a conductive polyester fiber containing 5 to 15% by weight of an inhibitor is provided.

  The conductive brush of the present invention is excellent in durability and has little variation in electric resistance value, and can be suitably used particularly for an image forming apparatus.

  The conductive brush of the present invention is a brush made of a pile fabric having pile yarns raised or raised on the surface of a base fabric. The pile fabric may be a woven fabric or a knitted fabric, but is preferably a woven fabric from the viewpoint of durability of the brush. The fibers constituting the base fabric may be polyester fibers, polyamide fibers, vinylon fibers, etc., but polyester fibers are particularly preferable from the viewpoint of durability.

  Next, an example of the pile fabric will be described with reference to the drawings. As shown in FIGS. 1 and 2, the pile fabric is piled so as to be entangled in a U-shape with a base fabric 3 composed of a woven fabric obtained by weaving warp yarn 1 and weft yarn 2 and weft yarn 2 of base fabric 3. It comprises a plurality of pile yarns 5 woven by weaving. As the warp yarn 1 and the weft yarn 2 forming the base fabric 3, it is preferable to use yarn having high durability and flexibility. Examples of such yarn include filament yarn, spun yarn, cotton yarn and the like. In this embodiment, the warp yarn 1 and the weft yarn 2 are highly flexible and bulky spun yarn. The pile yarn 5 is formed of a plurality of conductive polyester fibers, preferably twisted conductive polyester fibers, and each conductive polyester fiber spreads at the upper end thereof to be raised on the base fabric 3. Yes. Further, a synthetic resin coating layer 4 may be formed on the back surface of the base fabric 3, and the base of the pile yarn 5 and the base fabric 3 can be firmly joined by this coating layer 4.

  As long as the conductive brush of the present invention is made of the above-mentioned pile fabric, for example, even when the fabric is bonded and fixed to a flat surface, the fabric is spirally wound around a support as shown in FIG. It may be of a shape.

  In the present invention, it is important that the pile yarn is composed of conductive polyester fibers containing polyoxyalkylene glycol and an ionic antistatic agent in the amounts described later.

  The polyester constituting the conductive polyester fiber is a high molecular weight product in which a hydrocarbon group is connected to the main chain via an ester bond, and examples thereof include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. However, polyethylene terephthalate is particularly preferable not only from the viewpoint of durability as a conductive brush, but also from the viewpoint of versatility and yarn-forming properties.

  Further, it is necessary that the polyoxyalkylene glycol has substantially no reactivity with the polyester. Here, having substantially no reactivity means not copolymerizing with polyester. If the polyoxyalkylene glycol has reactivity with the polyester, it becomes difficult to control during blending.

  Specific examples of such polyoxyalkylene glycol include polyoxyethylene glycol having an average molecular weight of 6,000 or more, preferably 10,000 or more, or mainly oxyethylene units (usually 50% or more). Those containing propylene units are preferably used.

  In addition, the end of the polyoxyalkylene glycol may be a hydroxyl group, blocked with a non-ester-forming organic group, or bonded to another ester-forming organic group by an ether bond, an ester bond, a carbonate bond, or the like. May be. If the terminal is blocked with a non-ester-forming organic group, the average molecular weight of the polyoxyalkylene glycol may be as low as about 800 to 4,000.

  The content of the polyoxyalkylene glycol in the polyester is 5.0% by weight or less, preferably 3.0% by weight or less.

On the other hand, as the ionic antistatic agent used in the present invention, an anionic antistatic agent, a cationic antistatic agent, or a mixture thereof such as polyethylene glycol, polybutylene glycol, polyalkyl (or aryl, or alkylaryl) sulfone. acid metal salts, polyalkyl (or aryl or alkylaryl) amines, polyalkylene oxide addition alkyl (or aryl or alkylaryl) an amine, and the like, of the anionic antistatic agents having inter alia -SO 3 _M In particular, a metal salt of alkylaryl or aralkylsulfonic acid represented by the general formula RSO ₃ M is preferably employed. Here, M represents an alkali metal and is usually sodium, potassium or lithium, with sodium being particularly preferred. R represents an alkyl group having 8 or more carbon atoms. When the number of carbon atoms is 7 or less, the compatibility with polyester is slightly deteriorated. Therefore, usually, R is an alkyl group having 8 to 20 carbon atoms and is often used as a mixture thereof.

  The content of the alkylsulfonic acid metal salt in the polyester is 2.0% by weight or less, preferably 1.0% by weight or less.

  From the above, the content of the polyoxyalkylene glycol and the ionic antistatic agent is 5 to 15% by weight, preferably 5 to 10% by weight in consideration of the fiber physical properties. The former preferably accounts for 50 to 90% by weight.

  Further, the lower limit is at least about 5% by weight, and if it is less than this, the high conductivity intended in the present application cannot be obtained.

  In the present invention, it is preferable that the conductive polyester fiber has a hollow portion continuous in the fiber direction in order to exhibit high conductivity with as small an amount of antistatic agent as possible. The hollow ratio of the hollow portion is desirably 15% or less, particularly 4% or less. When the hollow portion exceeds 15%, the single fiber itself is easily divided into fibrils, and the mechanical performance of the fiber is significantly damaged. On the other hand, the lower limit of the hollow ratio is not particularly limited as long as there is a continuous hollow portion in the fiber direction, but is preferably about 0.005% in order to achieve higher conductivity.

  In the above conductive polyester fiber, when a hollow portion is provided in the cross section, if the shape of the fiber is a polymer layer continuous in the fiber direction, the outer shape and the shape of the hollow portion are round, each side of the outer shape Is a polygonal fiber with an inward convex shape and a hollow hollow part, or a circular outer shape with a hollow hollow part, a deformed outer shape and hollow part, and a hollow part with two to four. Is mentioned.

  Examples of the method for incorporating polyester fiber with polyoxyalkylene glycol and ionic antistatic agent include a method of melting polyoxyalkylene glycol and ionic antistatic agent into polyester pellets, high concentration polyoxyalkylene glycol and ions in polyester pellets. A method of blending and melting master pellets containing an antistatic agent, a method of adding and kneading polyoxyalkylene glycol and an ionic antistatic agent to a molten polyester, and a high concentration of a molten polyester to a molten polyester Examples thereof include a method of kneading polyester containing oxyalkylene glycol and an ionic antistatic agent.

  The conductive polyester fiber used in the present invention is obtained by melt spinning. In the spinning method, the raw material polymer is melted, discharged from a discharge hole, cooled, and oiled, and then the undrawn yarn is wound once at a speed of 500 to 2,000 m / min. The wound unstretched yarn is placed on a stretching machine and stretched about 1.5 to 5 times to obtain the target fiber.

  As a manufacturing method of a pile fabric, it can manufacture using a well-known method. For example, in the case of a pile fabric, a cloth such as the moquette / velvet shown in FIG. 1 described in detail above can be manufactured by a known method. In this case, the conductive polyester fiber may be used only for at least 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.

  For example, as shown in FIG. 2, the method for producing a conductive brush of the present invention is to form a pile fabric produced by the above-described method in a brush shape by spirally winding the fabric around a support. 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 polyester fiber of the present invention is preferably 10 ² to 10 ¹¹ Ω / cm. Preferably, a temperature of 20 ° C. and a humidity of 40% RH is 10 ⁸ 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.

Hereinafter, the present invention will be described in more detail with reference to examples. The evaluation method is as follows.
(1) Electrical resistance value of conductive fibers Using a resistance measuring instrument, a voltage of 1,700 V is applied between 10 cm of conductive fibers, and the electrical resistance values of the five cross sections under the conditions of a temperature of 20 ° C. and a humidity of 40% RH. (Ω / cm) was measured.
(2) Durability of the conductive brush JIS L1096 8.17.3 In the friction strength test of the C method (Taber type method), the load was 4.90 N, the wear wheel No. The wear durability of the conductive brush was measured with CS-17 and 500 wear times. As the evaluation method, JIS L1096 8.17.3 c) Appearance change determination was applied mutatis mutandis.
A: No abnormality.
B: Damage or pile is slightly reduced.
C: Warp or weft is cut. Alternatively, the pile is greatly reduced.
(3) Image quality A test chart issued by the Electrophotographic Society was copied, and the image quality after one print was determined by sensory evaluation (satisfaction) and evaluated according to the following criteria.
Good: Satisfaction 75 or higher, Slightly poor: Satisfaction 50 or higher, lower than 75

[Example 1]
A 2: 1 mixed antistatic agent of polyoxyethylene glycol having an average molecular weight of 20,000 and sodium alkyl sulfonate having an average carbon number of 12 to 13 is mixed with 6.0% by weight of 94.0% by weight of polyethylene terephthalate pellets. The melt mixed polymer yarn discharged from the discharge hole was cooled with cooling air using a hollow spinneret, and the undrawn yarn was taken up at a winding speed of 1,200 m / min. This was wound up. Next, the obtained unstretched yarn was stretched 2.95 times between the supply roller and the take-up roller using a drawing device installed in the order of the supply roller temperature 80 ° C., the heater temperature 210 ° C. and the take-off roller. A conductive polyester fiber of 250 dtex 40 filaments with a single fiber hollow ratio of 1.7% was obtained. A pile woven fabric (velvet) using this fiber as a pile yarn was manufactured to produce a conductive brush. 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. The results are shown in Table 1.

[Example 2]
Conductivity in the same manner as in Example 1 except that the hollow spinneret was changed to a spinneret capable of obtaining a higher hollow ratio and the amount of cooling air was increased under the spinneret so that the hollow ratio of the single fiber was 15%. Polyester fibers were obtained, pile fabrics were produced, and conductive brushes were produced. The results are shown in Table 1.

[Example 3]
Polyethylene terephthalate pellets (92.0% by weight) were mixed with polyoxyethylene glycol having an average molecular weight of 20,000 and sodium alkyl sulfonate having an average carbon number of 12 to 13 of 2: 1 mixed antistatic agent (8.0% by weight). Except for the above, conductive polyester fibers were obtained in the same manner as in Example 1, pile fabrics were produced, and conductive brushes were produced. The results are shown in Table 1.

[Comparative Example 1]
Polyethylene terephthalate pellets 97.0% by weight were mixed with 3.0% by weight of a 2: 1 mixed antistatic agent of polyoxyethylene glycol having an average molecular weight of 20,000 and sodium alkyl sulfonate having an average carbon number of 12-13. Except for the above, conductive polyester fibers were obtained in the same manner as in Example 1, pile fabrics were produced, and conductive brushes were produced. The results are shown in Table 1.

[Comparative Example 2]
Polyethylene terephthalate pellets 97.0% by weight were mixed with 3.0% by weight of a 2: 1 mixed antistatic agent of polyoxyethylene glycol having an average molecular weight of 20,000 and sodium alkyl sulfonate having an average carbon number of 12-13. Except for the above, a conductive polyester fiber was obtained in the same manner as in Example 2, a pile fabric was produced, and a conductive brush was produced. The results are shown in Table 1.

[Comparative Example 3]
20.0% by weight of 2: 1 mixed antistatic agent of polyoxyethylene glycol having an average molecular weight of 20,000 and sodium alkyl sulfonate having an average carbon number of 12 to 13 was mixed with 80.0% by weight of polyethylene terephthalate pellets. Except for the above, conductive polyester fibers were obtained in the same manner as in Example 1, pile fabrics were produced, and conductive brushes were produced. The results are shown in Table 1.

[Comparative Example 4]
A polyethylene terephthalate pellet containing 17.0% by weight of conductive carbon was mixed with 90.0% by weight of polyethylene terephthalate master pellets, the melt temperature was 295 ° C., and the mixed polymer discharged from the discharge holes was mixed. Winding was performed at a winding speed of 1200 m / min. This undrawn yarn was drawn 2.95 times between the supply roller and the take-off roller using a drawing device installed in the order of a supply roller temperature of 80 ° C., a heater temperature of 210 ° C. and a take-off roller, and 250 decitex 40 filaments Conductive polyester fibers were obtained. Using this fiber, a pile fabric was produced in the same manner as in Example 1 to produce a conductive brush. The results are shown in Table 1.

[Comparative Example 5]
A pile woven fabric was produced in the same manner as in Example 1 using a rayon filament of 330 dtex 48 filaments, and a conductive brush was produced. The results are shown in Table 1.

  The conductive brush of the present invention is excellent in durability and has little variation in electric resistance value, and can be suitably used particularly for an image forming apparatus, and its industrial utility value is extremely high.

The perspective view which shows an example of the pile fabric which comprises the electroconductive brush of this invention. The (A) front view and (B) side view which show an example of the cross-section of the pile fabric which comprises the electroconductive brush of this invention. The figure which shows an example of the electroconductive brush of this invention.

Explanation of symbols

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

Claims (6)

  It consists of a pile fabric having a pile yarn raised or raised on the surface of the base fabric, and the pile yarn contains 5 to 15% by weight of polyoxyalkylene glycol and ionic antistatic agent which are not substantially reactive with polyester. A conductive brush comprising a conductive polyester fiber.   The conductive brush according to claim 1, wherein the conductive polyester fiber is a conductive polyester fiber having a hollow ratio of 40% or less.   The conductive brush according to claim 1, wherein the polyoxyalkylene glycol has a molecular weight of 6,000 or more. The conductive brush according to claim 1, wherein the ionic antistatic agent has a —SO ₃ M (wherein M represents an alkali metal) group. 2. The conductive brush according to claim 1, wherein the ionic antistatic agent is a compound represented by RSO ₃ M (wherein R represents an alkyl, aryl, aralkyl group, and M represents an alkali metal group).   The conductive brush according to claim 1, wherein the pile yarn is a conductive polyester fiber having a ratio of polyoxyalkylene glycol and ionic antistatic agent of 9: 1 to 1: 1.

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