JP4452859B2 - Conductive multileaf fiber and electrophotographic brush using the same - Google Patents

Description

  The present invention relates to a conductive multileaf cross-section fiber and a brush for an electrophotographic apparatus using the same, and in particular, a multifilament and a monofilament composed of a single fiber containing conductive fine particles and having a multileaf cross section shape of three or more leaves. The present invention relates to a conductive multileaf fiber suitable for various brushes used in electrophotographic apparatuses (copiers, facsimiles, printers, and composite machines thereof) and a brush for an electrophotographic apparatus using the fibers.

  Conventionally, in an electrophotographic apparatus such as an electrophotographic copying machine, a non-contact type corona charging method has been adopted as an electrostatic latent image method formed on a photosensitive drum. However, the corona charging method is regarded as a problem that ozone generated from corona discharge deteriorates parts of the electrophotographic apparatus. This ozone is harmful to the human body. Furthermore, a high voltage must be used for corona discharge, and there is a risk of fire and the like.

  In order to solve this problem, a low-voltage contact charging method that does not use corona discharge has recently been proposed for electrophotographic apparatuses. For example, a contact charging method using a conductive multifilament yarn as a contact charging brush has been proposed.

  Conventionally, cellulose-based fibers are often used as the conductive multifilament yarn. Also, many polyester fibers and polyamide fibers widely used as synthetic fibers have been proposed which contain conductive fine particles.

  For example, Patent Document 1 discloses a composite fiber obtained by bonding a conductive component containing conductive fine particles to a thermoplastic resin such as polyamide, polyester, and polyolefin, and a non-conductive component not containing conductive fine particles. In addition, there is described a composite fiber having a multi-leaf shape with a cross section having at least four protrusions, and a conductive component arranged so as to be exposed at the tips of all the protrusions.

  Patent Document 2 discloses a multi-leaf shape having at least four protrusions in the cross section, a conductive component containing conductive fine particles in a thermoplastic resin such as polyamide, polyester, and polyolefin, and conductive fine particles. And a non-conducting component that does not contain a non-conducting component, and a composite fiber in which the non-conducting component is a core portion and the conductive component is disposed as a sheath covering all of the core portion in a cross section.

  Patent Document 3 discloses a composite fiber composed of a polyamide containing conductive carbon black and another thermoplastic resin, and has a multi-branched cross-sectional shape having three or more protrusions. A composite fiber in which a polyamide containing carbon black is exposed at the tip of each protrusion is described.

  According to these composite fibers, since the conductive component containing conductive fine particles at a high concentration is arranged at the tip of the projection, the conductive component of the brush using this composite fiber is always in contact with the photoreceptor. By this, it is excellent in electroconductivity and there exists an effect that a fiber strength can be made into the same level as a normal synthetic fiber.

However, in the conjugate fibers described in Patent Documents 1 and 3, a conductive component is disposed at the tip of the protrusion, and a non-conductive component is disposed in the recess between the protrusion and the protrusion. When such a fiber is used as a brush for an electrophotographic apparatus, that is, a charging brush or a cleaning brush, there are the following problems.
When used as a charging brush, charging due to discharge from the conductive component of the protrusion and charging due to discharge from the non-conductive component of the recess occur. That is, even a non-conductive component is not completely insulative and has conductivity through a nearby conductive component. However, since the discharge from the non-conductive component is weaker than the discharge from the conductive component, charging spots occur.
When used as a cleaning brush, cleaning spots occur due to the difference in the degree of adhesion of the toner component between the conductive component and the non-conductive component.

  In addition, the composite fiber described in Patent Document 2 appears to have charged spots and cleaning spots although only the conductive component covers the fiber surface at first glance. That is, normally, when used for a brush for an electrophotographic apparatus, the fiber has a short cut shape, and when the fiber comes into contact with a photosensitive drum or the like, the longitudinal surface of the fiber (fiber surface) In some cases, the leading end surface of the cut fiber (cross section cut perpendicular to the longitudinal direction of the fiber) may contact. In the case of this composite fiber, only the conductive component is present on the longitudinal surface of the fiber, but both the conductive component and the non-conductive component are present on the tip surface. A difference in sex occurred, causing charging spots and cleaning spots.

  Furthermore, Patent Document 4 discloses a composite of a conductive polymer layer and a thermoplastic polyamide layer as a conductive composite fiber that can solve the above-described problems and can form a high-quality image over a long period of time. A composite fiber is described in which the cross-sectional shape is substantially the same in the length direction of the fiber, but randomly differs between single fibers, and one polymer forms a layered divided layer.

  Indeed, according to this composite fiber, there is little change in conductivity due to long-term use, but again, because the composite fiber is a mixture of conductive polymer and non-conductive polymer, the resistance value of the fiber surface is uneven. Thus, the same problems as those of the conjugate fibers described in Patent Documents 1 to 3 have occurred. Further, in order to form such a layered divided layer, it is necessary to use a special polymer as a polyamide component, which is disadvantageous in terms of cost.

Furthermore, since the conductive fibers described in Patent Documents 1 to 4 are composite fibers as described above, the structure of the base is complicated when spinning, and it is difficult to reduce the fineness of the single fibers. (The fibers described in Examples of Patent Documents 1 to 4 have a single yarn fineness of about 6 dtex). However, when used as a charging brush among brushes for an electrophotographic apparatus, it is preferable that fibers are arranged at high density as a brush in order to achieve uniform charging performance, and a fiber having a small single yarn fineness. Is desired. Also, when used as a cleaning brush, since the toner particle size has been reduced, a finer yarn has been desired.
JP-A-11-65225 Japanese Patent Laid-Open No. 11-65227 JP 2002-309446 A JP 2002-309449 A

  The present invention solves the above problems and is a synthetic fiber that can be used for various brushes for an electrophotographic apparatus, and has excellent conductivity and uniformity of electrical performance as a whole fiber, Even if the fiber shape changes due to changes over time, there is no change in the conductive performance, so it is possible to obtain a good quality image, and it is advantageous in terms of cost, and the fineness of the single fiber An object of the present invention is to provide a conductive multilobal cross-section fiber that can also achieve the effect of the modification. Furthermore, the present invention is a brush for an electrophotographic apparatus using at least a part of the above-described conductive multileaf fiber, and when used as a charging brush or a static elimination brush, it can impart a uniform charge and eliminate static electricity. When used as a cleaning brush or a toner supply brush, it is technically possible to provide a brush for an electrophotographic apparatus that can uniformly remove and apply toner, and thus can obtain a uniform and good image. It is to be an issue.

ただし、Ｒ：外接円の半径（μｍ）、 ｎ：単繊維のデシテックス数、 ρ：繊維の密度（ｇ／ｃｍ ^３ ）、π：円周率である。
１．２ｒ≦Ｒ≦２．０ｒ・・・（２）
ただし、ｒ：内接円の半径、Ｒ：外接円の半径である。
１．２Ｎ≦Ｍ≦２．０Ｎ・・・（３）
ただし、Ｍ：葉部における底辺の長さ、Ｎ：葉部の高さ（Ｈ）の１／２の位置（Ｈ／２）において底辺と平行にひいた辺の長さである。 The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems.
That is, the gist of the present invention is the following (I) and (II) .
(I) A multifilament made of a thermoplastic resin containing conductive fine particles, wherein the single fiber constituting the multifilament is a fiber made only of a thermoplastic resin containing conductive fine particles, and the longitudinal direction of the fiber The cross-sectional shape cut perpendicularly to the cross-section exhibits a multi-leaf cross-sectional shape of three or more leaves, and the multi-leaf cross-sectional shape of a single fiber constituting the multifilament satisfies the following expressions (1), (2), and (3) Conductive multilobal cross-section fiber characterized by the above.

Where R: radius of circumscribed circle (μm), n: decitex number of single fiber, ρ: density of fiber (g / cm ³ ), π: circumference.
1.2r ≦ R ≦ 2.0r (2)
Here, r is the radius of the inscribed circle, and R is the radius of the circumscribed circle.
1.2N ≦ M ≦ 2.0N (3)
However, M is the length of the base in the leaf portion, and N is the length of the side that is parallel to the base at a position (H / 2) that is 1/2 of the height (H) of the leaf portion.

ただし、Ｒ：外接円の半径（μｍ）、ｎ：単繊維のデシテックス数、ρ：繊維の密度（ｇ／ｃｍ ^３ ）、π：円周率である。
２．０ｒ≦Ｒ≦３．５ｒ・・・（５）
ただし、ｒ：内接円の半径、Ｒ：外接円の半径である。
０．５Ｎ≦Ｍ≦１．５Ｎ・・・（６）
ただし、Ｍ：葉部における底辺の長さ、Ｎ：葉部の高さ（Ｈ）の１／２の位置（Ｈ／２）において底辺と平行にひいた辺の長さである。 (II) A cleaning brush for an electrophotographic apparatus, wherein the fibers used in at least a part of the cleaning brush for an electrophotographic apparatus are multifilaments made of a thermoplastic resin containing conductive fine particles, The constituting single fiber is a fiber composed only of a thermoplastic resin containing conductive fine particles, and has a multi-leaf cross-sectional shape in which the cross-sectional shape cut perpendicularly to the longitudinal direction of the fiber has three or more leaves, Is a conductive multi-leaf cross-section fiber characterized in that the multi-leaf cross-sectional shape of the single fiber constituting the multifilament satisfies the following formulas (1), (5) and (6): Cleaning brush.

Here, R: radius of circumscribed circle (μm), n: decitex number of single fiber, ρ: density of fiber (g / cm ³ ), π: circumference.
2.0r ≦ R ≦ 3.5r (5)
Here, r is the radius of the inscribed circle, and R is the radius of the circumscribed circle.
0.5N ≦ M ≦ 1.5N (6)
However, M is the length of the base in the leaf portion, and N is the length of the side that is parallel to the base at a position (H / 2) that is 1/2 of the height (H) of the leaf portion.

  Since the conductive multileaf fiber of the present invention is a fiber composed only of a thermoplastic resin containing conductive fine particles, the entire fiber is excellent in uniformity of the conductive performance, and changes into a fiber shape after long-term use. Even if this occurs, there is no change in the conductive performance, and it can be advantageously obtained in terms of cost. Furthermore, since the single fiber constituting the conductive multileaf fiber has a multileaf cross-sectional shape having a cross-sectional shape of 3 or more leaves, the contact point by the leaf portion is 2 points or more, and therefore it has excellent conductivity. In addition, the same effect as that of a fine yarn can be obtained. Further, since the surface area of the fiber is increased as compared with the round cross-section yarn, the cleaning effect is also excellent.

  Further, the brush for an electrophotographic apparatus of the present invention uses the conductive multileaf cross-section fiber of the present invention for at least a part thereof, so that multipoint contact by a leaf portion is possible and when a fine yarn is used. It becomes possible to set it as the brush which arrange | positioned the fiber at high density similarly to.

  In general, there is a cleaning brush that cleans an image carrier such as a photosensitive member or an intermediate transfer member and applies a solid lubricant to the image carrier. In the brush of the present invention, since the conductive multileaf fiber has irregularities on the surface thereof, it is easy to hold the solid lubricant, and the coating amount is made uniform and stabilized. Is also effective.

Furthermore, the conductive multileaf cross-section fiber of the present invention has a multileaf cross-sectional shape of a single fiber constituting a multifilament, where r is a radius of an inscribed circle and R is a radius of a circumscribed circle,
1.2r ≦ R ≦ 2.0r
By satisfying the expression, the stem (referring to a portion other than the leaf in the cross-sectional shape) is relatively thick compared to the leaf, so it is superior in workability than a brush using a fine yarn, It can be stiff. For this reason, uniform charging and discharging can be performed when charging and discharging by contacting the photosensitive drum. When used as a cleaning brush and a toner supply brush, uniform removal and application of toner are performed. Therefore, it is possible to obtain a uniform and good image without a group over a long period of time.

Hereinafter, the present invention will be described in detail.
First, the brush for an electrophotographic apparatus referred to in the present invention is various brushes used for an electrophotographic apparatus such as a copying machine, a facsimile, a printer (for example, a laser beam printer), for example, a developing brush, a contact charging brush, and a static eliminating brush. Examples include brushes, cleaning brushes, and toner supply brushes. The conductive multileaf fiber of the present invention can be suitably used for contact charging brushes, static elimination brushes, cleaning brushes, toner supply brushes and the like.

  The polymer that forms the conductive multilobal cross-section fiber of the present invention is not particularly limited as long as it is a fiber-forming thermoplastic polymer, and examples thereof include polyester, polyamide, polyethylene, and polypropylene. Of these, polyester and polyamide are preferred.

  More specifically, polyesters include, for example, polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, those obtained by copolymerizing a dicarboxylic acid component, a diol component or an oxycarboxylic acid component, or a blend of these polyesters. It is done. Furthermore, aliphatic polyesters such as polylactic acid, polybutylene succinate and polyε-caprolactam known as biodegradable polyesters may be used.

  Examples of the polyamide include nylon 6, nylon 66, nylon 69, nylon 46, nylon 610, nylon 12, polymetaxylene adipamide, and those obtained by copolymerizing or blending these components.

  Conductive fine particles are contained in each single fiber constituting the conductive multileaf fiber of the present invention. Examples of the conductive fine particles include carbon black, metal powder, metal oxide, and the like. Among these, carbon black is preferable. The amount to be added is, for example, preferably 5 to 30% by mass, more preferably 10 to 25% by mass in the case of polyester. In polyamide, 15-45 mass% is preferable, More preferably, it is 20-35 mass%.

  As described in Patent Documents 1 to 4, conventionally, conductive fibers in which conductive fine particles are uniformly dispersed are difficult to manufacture, and the strength of the obtained fibers is low and the cost is high. was there. In other words, carbon black is usually used as the conductive fine particles, but since carbon black has a lower specific heat than thermoplastic resin, the cooling rate after spinning is faster than that of fibers not containing carbon black. This occurs. This phenomenon becomes more prominent as the carbon black content increases, but due to the high cooling rate, fiber stiffening and yarn breakage during stretching become difficult, making it difficult to manufacture, It was.

  In consideration of such a phenomenon, the present invention can obtain a conductive multileaf fiber made of only a thermoplastic resin containing conductive fine particles by appropriately selecting various conditions in the manufacturing process. It was made. That is, for example, in the spinning process, the shape of the spinneret, the spinning speed, and the cooling conditions can be optimized to stabilize the shape of the fiber and prevent the fiber from becoming rigid due to rapid cooling. Is possible. In the drawing step, it is possible to stably obtain conductive multileaf fiber having practical strength by optimizing conditions such as drawing speed and temperature.

  As described above, the conductive multileaf fiber of the present invention is composed only of a thermoplastic resin containing conductive fine particles. In other words, each single fiber constituting the conductive multileaf fiber has a single layer structure in which only a thermoplastic resin containing conductive fine particles is used as a constituent polymer and no other non-conductive resin is used. . For this reason, even if the fiber shape changes due to use, there is no change in the conductive performance, the conductivity as a whole of the fiber and the uniformity of the conductivity are excellent, and the cost can be obtained advantageously. Can do.

And each single fiber which comprises an electroconductive multileaf cross-section fiber is exhibiting the multilobe cross-section shape where the cross-sectional shape cut | disconnected perpendicularly | vertically with respect to the longitudinal direction of a fiber is three or more leaves.
The multi-leaf cross-sectional shape has a plurality of concave and convex portions on the outer peripheral surface in the cross-sectional shape of a single fiber, and a convex portion sandwiched between adjacent concave portions and the concave portion is a leaf portion. And each single fiber of the electroconductive multileaf cross-section fiber of this invention has three or more leaf parts. The upper limit of the number of leaf parts is not particularly limited, but is preferably 3 to 20, and particularly preferably a six-leaf cross-sectional shape having six leaf parts.

  Such a cross-sectional shape will be described with reference to the drawings. 1A and 1B are schematic cross-sectional views showing an embodiment of a three-leaf cross-sectional shape. 2A and 2B are schematic cross-sectional views showing an embodiment of a four-leaf cross-sectional shape. 3A and 3B are schematic cross-sectional views showing an embodiment of a six-leaf cross-sectional shape.

  In the present invention, a multi-leaf cross-sectional shape results in that there are a plurality of leaf portions that are projections for each single fiber, and the plurality of leaf portions that are projections are brushes for an electrophotographic apparatus. In this case, the portion comes into contact with the photosensitive drum or the like. That is, in a fiber having a normal round cross-sectional shape or a polygonal cross-sectional shape such as a square, there is only one portion in contact with a photosensitive drum or the like in one single fiber, but the multi-leaf cross-sectional shape of the present invention Then, by using multi-leaf cross-section fibers of three or more leaves, at least two leaf portions are in contact with the photosensitive drum or the like with one single fiber, and there are two or more contact points.

As a result, the following effects are produced when charging and discharging brushes, cleaning brushes, and toner supply brushes.
First, when using the conductive multileaf fiber of the present invention as a charging brush or a static elimination brush, it is important to make the charging and static elimination more uniform. It is effective to make a brush in which finer fibers are planted at a higher density. The uniformity of the electrical conductivity of the fiber can be realized by using a monodispersed conductive yarn, but it is impossible to make the conductive yarn infinitely thin. However, when comparing the multi-leaf cross-section yarn and the round cross-section yarn of the same thickness, when the tip of the leaf portion of the multi-leaf cross-section yarn is approximated by an arc, the radius of the arc is set to 1 / of the radius of the round cross-section yarn. 2 or less. Reducing the arc in contact with the member to be charged is substantially equivalent to using thinner fibers. In addition, since the multi-leaf cross-sectional yarn has a larger number of contact points with the member to be charged than the round cross-sectional yarn, it can be made substantially equivalent to a densified brush. As a result, it is possible to provide a charging brush and a static eliminating brush that are remarkably superior in chargeability, charge-removing property and uniformity thereof than those using conventional composite yarns and round cross-section yarns.

  Further, when a cleaning brush is formed using the conductive multi-leaf fiber of the present invention, the leaf portion that has become a protruding portion works to scrape off the toner, and the presence of a plurality of these portions results in a scraping effect. It will be excellent. Further, since the multi-leaf cross-sectional shape increases the surface area as compared with the fiber having a round cross-sectional shape, and because there are a plurality of concave portions adjacent to the leaf portion, the amount of retained toner scraped off. It can be increased and an excellent cleaning effect can be shown.

  Furthermore, since each single fiber is a multi-leaf cross-section fiber, it becomes bulky compared to a round cross-section fiber, so when used as a brush, the surface density is higher than that of a round cross-section fiber brush planted at the same density. , Can be bulky. Thereby, it can be set as the above-mentioned brush excellent in the charge and static elimination, and the cleaning effect of a toner particle.

  That is, when making various brushes for an electrophotographic apparatus, a fiber is woven to form a pile fabric, and the fabric is cut into a tape shape and wound around a cylindrical shaft in a spiral manner. . At this time, since it is wound in a spiral shape, a gap is likely to be generated along the winding shape on the brush surface, and such a gap is a cause of spots in the flow of electricity and the cleaning effect. When the fiber of the present invention is used, the surface density increases, so that the volume feeling increases and a brush without a spiral gap can be obtained. As a result, uniform charging without charge, neutralization, and a cleaning effect can be realized.

  Furthermore, these events are also effective for the toner supply brush of the developing machine of the electrophotographic apparatus. Conventionally, sponge rolls have been widely used for toner supply in non-magnetic one-component developing machines. However, from the viewpoint of toner supply and release properties to the development roll, driving torque, and resistance value stability, etc. Brushes are being considered and switched. The brush is made by spirally winding a pile woven fabric around a shaft. However, it has been pointed out that a spiral gap is generated on the surface of the brush when it is wound, and this becomes a toner supply spot on the developing roll. Since the circumscribed circle of the 6-leaf cross-sectional yarn is larger than that of the round cross-sectional yarn, even if the hair is planted at the same density, the sense of volume increases and the spiral gap becomes inconspicuous. For this reason, the stability of toner supply to the developing roll is improved. In this case, if the flocking density is too high, toner clogging occurs in the brush, and therefore an appropriate density is desirable. According to the present invention, since the spiral gap can be eliminated while the density is moderate, a practical effect is great.

  In order to simply increase the surface density, a fine yarn may be used, and a brush using a round fine cross-sectional shape can be a brush without a spiral gap. However, since there is no fiber stiffness, there is no stiffness as a brush, and it is not particularly suitable as a cleaning brush for scraping off toner. Further, in the cleaning brush, it is important that the toner can be easily discharged at the same time as the toner is scraped, and a toner clog is generated in a brush having a high fiber density using only a fine yarn.

  As described above, the brush for an electrophotographic apparatus capable of exhibiting the effects of high surface density, firmness, and excellent toner retention and discharge properties has a very large practical effect.

  The number and shape of leaf parts are excellent for charging and discharging performance and toner particle cleaning effect when used as a fiber for a brush for an electrophotographic apparatus as described above, and it is easy to obtain a brush without a spiral gap. Among these, a fiber having a six-leaf cross-section is particularly preferable among the fibers having a multi-leaf cross-section.

And as for the conductive multileaf cross-section fiber of this invention, the multileaf cross-section shape of the single fiber which comprises a multifilament and a monofilament needs to satisfy the following (1) Formula.

ただし、Ｒ：外接円の半径（μｍ）、 ｎ：単繊維のデシテックス数、 ρ：繊維の密度（ｇ／ｃｍ^３）、 π：円周率である。

Where R: radius of circumscribed circle (μm), n: decitex number of single fiber, ρ: density of fiber (g / cm ³ ), and π: circumference ratio.

That is, since 1 decitex has a length of 10000 m and a mass of 1 g, in the case of a normal round cross-section yarn, its radius is R ₀ (μm),
_{n = π (R 0/1000} ) 2 × 10000 × ρ
From this equation,

となる。

It becomes.

  From this, the formula (1) shows that the radius of the circumscribed circle of the multi-leaf cross-section fiber is 1.1 times or more than the radius of the round cross-section fiber compared to the round cross-section fiber having the same decitex number. Yes. That is, it shows that there is a bulkiness of the fiber by using a multi-leaf cross-section fiber as compared with the round cross-section fiber.

  When the value of R is less than 1.1 of the radius of the round cross-section fiber, the shape of the multi-leaf cross-section fiber is close to that of the round cross-section fiber, and the electrical effect and cleaning effect peculiar to the multi-leaf cross-section fiber as described above are obtained. While it becomes small and bulkiness becomes scarce, it becomes difficult to make a brush with a high surface density.

Moreover, in the conductive multileaf cross-section fiber of this invention, it is necessary for the multileaf cross-sectional shape of the single fiber which comprises a multifilament and a monofilament to satisfy the following (2) Formula.
1.2r ≦ R ≦ 2.0r (2)
Here, r: radius of the inscribed circle, R: radius of the circumscribed circle Here, the inscribed circle is a circle drawn inside the cross-sectional shape so as to contact the vertices of a plurality of recesses, This is the circle with the largest radius among the circles drawn to touch. The circumscribed circle is a circle drawn on the outside of the cross-sectional shape so as to be in contact with the vertices of a plurality of leaf portions, and is the circle with the largest radius among the circles drawn so as to be in contact with the vertices of the most leaf portions.

Expression (2) is an index indicating the length of the leaf portion in the multi-leaf cross-sectional shape of the single fiber. When R is smaller than 1.2 r, it becomes a shape with a small unevenness difference between the leaf portion and the concave portion, is close to a polygonal shape or a round cross-sectional shape, the contact point of the leaf portion becomes small, and the leaf portion as described above It becomes difficult to achieve the effect of contact due to. On the other hand, when R is larger than 2.0 r, the leaf protrusions are large and the trunk is small, so that the stiffness of the fibers is poor and it is difficult to stably produce a uniform shape. It is easy to become.

Among them, the conductive multileaf fiber of the present invention is used as an application that places importance on electrical performance, for example, when used for a charging brush or a static elimination brush,
1.2r ≦ R ≦ 2.0r (2)
And the shape of the leaf portion of the multifilament cross-section of the single fiber is 1.2N ≦ M ≦ 2.0N (3)
It is necessary to satisfy

However, M is the length of the bottom side of the leaf part, and N is the length of the side drawn in parallel with the bottom side at the position of 1/2 of the height (H) in the leaf part, that is, H / 2.
Here, as shown in FIG. 4, the length (M) of the bottom of the leaf portion is the length of a straight line connecting the vertices of adjacent recesses, and the height (H) of the leaf portion is the leaf The length of a straight line drawn perpendicularly from the top of the part to the bottom of the leaf part. The length of the side drawn in parallel with the bottom side at the position of H / 2 is N.

  In addition, the cross-sectional shape of the single fiber in this invention measures and calculates what was image | photographed with the electron microscope, and the shape of a leaf part is H, M, N of all the leaf parts in one multileaf cross-sectional shape. Are measured and calculated, and evaluated by the average value of all these leaves. Furthermore, in a multifilament, it evaluates by the average value of these values measured and calculated about all the single fibers which comprise a multifilament.

When used for applications that place importance on electrical performance such as charging or static elimination, if the length of the protrusion on the leaf part becomes too long, it tends to repel when the leaf part comes into contact with it, and the entire brush can be discharged or discharged. It is inferior in the uniformity of static elimination, and it is easy to form a group in the conductive performance. Therefore, it is preferable that the stem has a certain amount of stem portion and the leaf portion is not excessively long, and therefore R ≦ 2.0r is required. .

Furthermore, when using for such a use, it is required that it is a shape where the front-end | tip of the leaf part in a multi-leaf cross-sectional shape of a single fiber becomes an acute angle to some extent. Since the tip of the leaf portion contacts the photosensitive drum or the like to perform discharge and charge removal, it is necessary for the contact point to be point contact, not surface contact, from the uniformity of discharge and charge removal.

Therefore, M is 1. If it is less than 2 N, the shape of the leaves is not sharp, that a close contact is surface contact at the tip of the leaves. On the other hand, M when exceeds 2.0 N, the shape of the leaves becomes too sharp, that Do a stable difficult to obtain a shape.

  And, when used for applications that place importance on such electrical performance, in order to increase the surface density of the brush or to increase the contact points of the leaves in the brush, the fineness of the single fiber is: It is preferable that it is 0.5-10.0 decitex.

In addition, when the conductive multileaf fiber of the present invention is used for a cleaning brush, for example, as an application that emphasizes the performance of removing toner,
2.0r ≦ R ≦ 3.5r (5)
And the shape of the leaf portion of the single-fiber multi-leaf cross-sectional shape is 0.5N ≦ M ≦ 1.5N (6)
It is necessary to satisfy

That is, in the present invention, as having excellent effects scraping toner, since the length of the projection of the leaf portion is required to be in some degree, it is necessary to 2.0R ≦ R as described above .

Further, in the present invention, for scraping the toner at the tip of the leaf, it is necessary to shape a less acute angle, it is necessary to M ≦ 1.5 N as described above. On the other hand, M and is 0.5N smaller, it becomes possible to leaf portions adjacent are close to scraping work of the toner is not performed satisfactorily, since the group is generated in the cleaning property, be a 0.5N ≦ M is necessary.

The conductive multileaf fiber satisfying the conditions of the formulas (5) and (6) is used for the toner supply brush.

Further, when used as a cleaning brush, the larger the surface area of a single fiber, the more toner adheres and the better the cleaning property. For this reason, it is preferable to satisfy the following formula (4) .

ただし、Ｓ：単繊維の周長である。

Where S is the circumference of the single fiber.

  That is, as mentioned above,

であるため、
Ｓ≧１．３×２πＲ_０
として、上記の（７）式が導き出される。

Because
S ≧ 1.3 × 2πR ₀
As a result, the above equation (7) is derived.

That is, the expression (7) indicates that the circumference of the multi-leaf cross-sectional fiber is 1.3 times or more than that of the round cross-section fiber having the same single yarn fineness.
When S is a value smaller than the right side of the expression (7), the fiber shape becomes close to a round cross-section fiber, and the surface area becomes small. Therefore, the amount of toner adhesion decreases and the cleaning performance cannot be improved.

In consideration of the need to scrape toner and to temporarily retain the scraped toner for use in cleaning applications, the single fiber fineness is 1.5 to 60 dtex. Is preferred. In order to use a brush for cleaning, there are several types of cleaning methods, and a thick thread may give a good result, while a thinner one may be better.

  The conductive multileaf fiber of the present invention may be a multifilament having a plurality of single fibers as described above or a monofilament composed of only the single fibers as described above. And in the case of a multifilament, it is preferable that the fineness of a multifilament is 20-600 dtex and the number of single fibers is 10-100, and in the case of a monofilament, it is preferable that the fineness is 10-500 dtex.

As described above, since the conductive multileaf fiber of the present invention is a fiber suitable for various brushes for an electrophotographic apparatus, the electrical characteristic value thereof is in an atmosphere of 20 ° C. and 60% RH. The specific resistance value is preferably 10 ³ to 10 ⁹ Ω · cm, and an appropriate resistance value is selected depending on the application of the brush. For example, the specific resistance value is preferably 10 ⁴ to 10 ⁶ Ω · cm in the case of a charging brush, and preferably 10 ³ to 10 ⁵ Ω · cm in the case of a static elimination brush. In the case of a cleaning brush, it is preferable to use a high resistance 10 ⁷ to 10 ⁹ Ω · cm, or conversely 10 ³ to 10 ⁶ Ω · cm, depending on the cleaning method. .

  Next, the manufacturing method of the electroconductive multileaf cross-section fiber of this invention is demonstrated using an example of the manufacturing method of a multifilament. In the case of multifilaments, (i) a two-step method in which unstretched yarn is wound once after spinning and then subjected to stretching in a stretching step; and (ii) unstretched yarn is wound once after spinning. It may be produced by any one of the one-step methods in which stretching is performed continuously. Here, a method of manufacturing by a two-step method will be described using an example.

  First, a conductive chip such as carbon black as described above or a master chip containing conductive fine particles and a thermoplastic polymer are kneaded and melted by, for example, an extruder and extruded from a spinneret by a conventionally known method, and melt spinning. I do. And an unstretched multifilament yarn is obtained, without extending | stretching substantially.

  At this time, as a method for kneading and melting the conductive fine particles and the thermoplastic polymer, the conductive fine particles can be directly kneaded using, for example, a biaxial extruder. However, it is preferable to once prepare a master chip containing conductive fine particles at a high concentration and then knead, because more uniform kneading is possible.

  As a melt spinning method, the spinning temperature is preferably in the range of Tm + 10 to Tm + 80 ° C. with respect to the melting point Tm of the resin used. When the spinning temperature is too high, the thermoplastic polymer undergoes thermal decomposition, making smooth spinning difficult, and resulting in inferior filament properties. On the other hand, if the spinning temperature is too low, undissolved materials remain and uniform kneading cannot be performed.

  Then, at the time of spinning, the slit shape of the spinneret is selected so that the multi-leaf cross-sectional shape to be obtained is obtained. In particular, when trying to make the shape of the leaf portion an acute angle, it is preferable to narrow the slit width or lengthen the slit length.

  Since the fiber of the present invention contains a relatively large amount of conductive fine particles, the cooling rate after spinning is increased as described above. However, the shape change of the fiber after spinning is reduced accordingly, and the desired multileaf is obtained. A cross-sectional shape is easily obtained.

  Then, the spun filament is cooled with cooling air of 0 to 100 ° C., preferably 15 to 40 ° C. If the cooling temperature is too low, the temperature management and workability will be difficult. On the other hand, if it is too high, cooling is insufficient and the yarn quality of the finally obtained filament is inferior.

  As described above, it is important to perform spinning by selecting appropriate values for the slit shape of the spinneret, the discharge amount of the polymer, the spinning speed, the cooling speed, etc., so as to obtain a fiber having a desired multileaf cross-sectional shape. is there.

Next, the cooled and solidified filament is temporarily wound at 500 to 1500 m / min without substantially stretching.
And it is preferable to give the unstretched multifilament yarn the heat stretching which extends | stretches, heat-treating. Specifically, the stretching temperature is preferably 50 to 200 ° C., the stretching ratio is 1.5 to 5.0 times, and the heat stretching is preferably performed so that the heat treatment time during the heat stretching is 0.02 seconds or more. . By setting the heat treatment time during stretching to 0.02 seconds or more, a sufficient amount of heat can be applied so that each single fiber is equally stretched, and the film can be slowly and uniformly stretched. As a result, the content of the conductive fine particles is relatively large, and therefore even a highly rigid fiber can be uniformly stretched without causing yarn breakage during stretching.

  The stretching speed is not particularly limited, but is preferably 500 m / min or less in order to make the heat treatment time 0.02 seconds or more. Moreover, it is preferable to perform a relaxation heat treatment as necessary after stretching.

  As described above, in the present invention, by appropriately selecting the spinning, stretching, and heat treatment conditions, a relatively large amount of conductive fine particles are contained in the thermoplastic resin, which has been difficult to produce conventionally. It is now possible to obtain a modified cross-section fiber using a polymer.

Next, the brush for an electrophotographic apparatus of the present invention will be described.
The brush of the present invention uses at least a part of the conductive multilobal cross-section fiber of the present invention, and the proportion of the conductive multileaf cross-section fiber of the present invention in the brush may be 50% by mass or more. Among them, it is preferable that the conductive multileaf fiber of the present invention is used. The form of the brush is not particularly limited, but after weaving the fiber of the present invention into a pile fabric, the pile fabric is cut into a tape shape and wound around the surface of a cylindrical shaft in a spiral shape to form a brush. The thing which was done is mentioned. Also, the fibers of the present invention are cut into short fibers and bonded to the fabric surface by flocking, and the fabric is similarly taped and spirally wound around the surface of the shaft to form a brush, or directly by flocking. Examples include a brush made by adhering short fibers to the surface of the shaft.

  Then, the brush of the present invention has a heat set by hot water treatment in order to open the fibers on the brush surface and prepare the brush surface after winding the pile fabric or the like spirally around the surface of the shaft as described above. It is preferred to do so. Since the brush of the present invention uses the conductive multileaf fiber of the present invention, the surface density of the brush is high due to the presence of the leaf portion and there is no spiral gap when the fiber is opened by such heat setting. A bulky brush with a volume feeling can be obtained.

Next, the present invention will be specifically described with reference to examples.
The cross-sectional shape of the conductive multileaf fiber in the following Examples and Comparative Examples was measured by the method described above.

  The electrical resistance value of the conductive multileaf fiber was determined as follows. That is, a bundle of multifilament fibers (48 filaments or 96 filaments) was brought into contact with a pair of electrodes spaced 15 mm apart, and a flowing current was measured by applying a DC voltage of 100 V between both electrodes. This was measured at 1000 points per cone, the resistance value of the fiber was calculated from the measured current value, and the average value of the resistance values at 1000 points was obtained (averaged with a logarithmic value). And from this resistance value, the volume resistance value was calculated | required based on the cross-sectional area and length of the fiber, and the electrical resistance value of the electroconductive multileaf cross-section fiber was evaluated by it.

  The strength and elongation of the conductive multilobal cross-sectional fibers were measured according to JIS L-1013 using Shimadzu Autograph DSS-500 at a grip interval of 25 cm and a tensile speed of 30 cm / min.

The density of the fiber was measured according to the density stir tube method of JIS L-1013.
The single fiber fineness (n) was determined by calculating the fineness of the multifilament according to JIS L-1013 and dividing it by the number of single yarns.

  The image evaluation of the charging brush was performed as follows. That is, it was mounted as a charging brush on a charging portion of a laser printer (product number LP3000C) manufactured by Seiko Epson Corporation, a halftone image was printed, and image quality, particularly image spots, was visually evaluated in 10 stages. That is, 10 was the most excellent. The deterioration of the charging brush with the passage of time is caused by the dirt on the brush, so that the difference between the brushes does not easily appear. Therefore, here, the evaluation was made based only on the quality of the initial image. The charging brush is rotated in the counter direction (i) counterclockwise (peripheral speed is twice the peripheral speed of the photoconductor) with respect to the rotation direction of the charged body (photosensitive body), and (ii) in the width direction. Evaluation was made with the case of rotational driving (peripheral speed is 1.1 times the peripheral speed of the photoreceptor).

The cleaning performance of the cleaning brush was evaluated by evaluating the image. At this time, since various cleaning methods have been put into practical use, the evaluation was performed by two methods here.
As one of these, we implemented it on the cleaner of the intermediate transfer drum of the color laser printer (part number BEAMSTAR-3000) manufactured by Hitachi Printing Solutions (a bias cleaner that electrostatically cleans the brush by applying a voltage of the opposite polarity to the toner). With the brushes of Examples and Comparative Examples attached, 50,000 color prints were made, and the cleaning state on the intermediate transfer drum was visually evaluated on a 10-stage basis for every fixed number of sheets (the most excellent one was set to 10). .

  As part 2, for the purpose of cleaning the charging roll of the Ricoh color laser printer (Part No. Ipsio 8000), the brushes of the examples and comparative examples were attached to perform 30,000 color prints, and the charging roll was stained. The accompanying image quality degradation state was visually evaluated on a 10-point scale (the best one was 10).

  The image evaluation of the toner supply brush was performed as follows. In other words, instead of the toner supply roll (sponge roll) of the non-magnetic one-component developing machine mounted on the color laser printer (product number LP3000C) manufactured by Seiko Epson, the brushes of the example and the comparative example were mounted, and 30,000 sheets Color printing was performed, and the image quality degradation state was visually evaluated on a 10-point scale (the best one was 10).

<Examples and comparative examples of charging brush>
Example 1 (6-leaf cross-sectional shape)
A master chip (35% carbon black was added to a nylon 6 chip having a relative viscosity of 2.50 (measured with 96% sulfuric acid as a solvent at a concentration of 1 g / dl and a temperature of 25 ° C.) to a carbon black concentration of 24.00% by mass. Nylon 6 (relative viscosity 1.95) chips containing mass% are blended and then fed to an extruder type melt extruder, melted at a spinning temperature of 255 ° C., and a thick hexagon as shown in FIG. The undrawn yarn was wound at a winding speed of 600 m / min while being discharged from a spinneret having 48 slit-shaped spinning holes having a radial shape and cooled by cooling air at 30 ° C.

  Next, the obtained undrawn yarn was drawn at a draw ratio of 2.6 times through a hot plate at 150 ° C., and then subjected to relaxation heat treatment for 1.9 seconds with a heater at 170 ° C. to obtain a single yarn fineness. Of 4.58 dtex and 220 dtex / 48 filaments of conductive six-leaf cross-section fibers were obtained. The fiber cross-sectional shape was as shown in FIG.

The obtained fibers were woven as a pile tape having a pile density of 200,000 pieces / (2.54 cm) ² , a pile length of 5 mm, and a fabric width of 15 mm, and then spirally wound around a metal shaft having a diameter of 6 mm to prepare a charging brush. . Thereafter, heat treatment for opening was performed with saturated steam at 100 ° C. for 5 minutes.

  Table 1 shows the properties of the obtained conductive fibers and brushes.

As shown in Table 1, since the single fiber fineness n of the fiber is 4.58 and the density ρ is 1.250, the value on the right side of the above equation (1) is 11.88. Formula (1) is R ≧ 11.88
However, as shown in Table 1, the value of R was 12.86, which satisfied the above formula.

  In addition, as shown in Table 1, the value of R / r is 1.3637, which satisfies the formula (3), and the value of M / N is 1.7366, which satisfies the formula (4). Met. Therefore, the electrical characteristics were excellent and the image evaluation value was high.

Examples 2-3 (6 leaves)
Table 1 shows the spinning temperature and the cooling air temperature. And otherwise, it carried out similarly to Example 1, and obtained the conductive fiber. A charging brush was also created.

Table 1 shows the properties of the obtained conductive fibers and brushes.
Also in this case, as in Example 1, the value of R satisfies the expression (1) and the value of R / r satisfies the expression (3) as shown in Table 1, and M The value of / N satisfied the expression (4). Therefore, the electrical characteristics were excellent and the image evaluation value was high.

Example 4 (3 leaves)
As the spinneret, a slit-shaped one having three thick radial shapes as shown in FIG. 1A was used, and the spinning temperature and cooling air temperature were set as shown in Table 1. And otherwise, it carried out similarly to Example 1, and obtained the 3 leaf cross-section fiber which has the conductivity of 220 dtex / 48 filament. The fiber cross-sectional shape was as shown in FIG.

A charging brush was prepared in the same manner as in Example 1.
Table 1 shows the properties of the obtained conductive fibers and brushes.
Similarly in this case, as shown in Table 1, the value of R satisfies the expression (1), the value of R / r satisfies the expression (3), and the value of M / N is (4) The expression was satisfied. Therefore, the electrical characteristics were excellent and the image evaluation value was high.

Example 5 (4 leaves)
As the spinneret, a slit-shaped one having a thick radial shape shown in FIG. 2A was used. And otherwise, it carried out similarly to Example 3, and obtained the 4-leaf cross-section fiber which has the conductivity of 220 dtex / 48 filament. The fiber cross-sectional shape was as shown in FIG. A charging brush was prepared in the same manner as in Example 1.

Table 1 shows the properties of the obtained conductive fibers and brushes.
Similarly in this case, as shown in Table 1, the value of R satisfies the expression (1), the value of R / r satisfies the expression (3), and the value of M / N is (4) The expression was satisfied. Therefore, the electrical characteristics were excellent and the image evaluation value was high.

Example 6 (6-leaf fineness)
Using a spinneret having 96 slit-shaped spinning holes exhibiting thick hexagonal radii as shown in FIG. 3 (a), the amount of carbon black added, spinning temperature, cooling air temperature, draw ratio, relaxation heat treatment time As shown in Table 1. And otherwise, it carried out similarly to Example 1, and obtained the 6-leaf cross-section fiber which has the single yarn fineness of 2.29 dtex, and is 220 dtex / 96 filaments and has electroconductivity. The fiber cross-sectional shape was as shown in FIG. A charging brush was prepared in the same manner as in Example 1.

Table 1 shows the properties of the obtained conductive fibers and brushes.
In this case, as shown in Table 1, since the single fiber fineness n of the fiber is 2.29 and the density ρ is 1.250, the value on the right side of the above-described formula (1) is 8.40. After all, the formula (1) is R ≧ 8.40
However, as shown in Table 1, the value of R was 9.09, which satisfied the above formula.

  Further, the value of R / r satisfies the expression (3), and the value of M / N satisfies the expression (4). Therefore, the electrical characteristics were excellent and the image evaluation value was high.

Comparative example 1 (round section)
A spinneret having a round slit shape was used, and the draw ratio and relaxation heat treatment time were as shown in Table 1. Otherwise, in the same manner as in Example 1, a 220 dtex / 48 filament conductive fiber having a round cross section as shown in FIG. 5 was obtained. A charging brush was prepared in the same manner as in Example 1.

Table 1 shows the properties of the obtained conductive fibers and brushes.
In this case, as in the case of Example 1, the formula (1) is R ≧ 11.88.
However, as shown in Table 1, the value of R was 10.84, which did not satisfy the above equation. For this reason, the image evaluation value was low.

Comparative example 2 (triangular section)
A spinneret having a triangular slit shape was used, and the spinning temperature and cooling air temperature were as shown in Table 1. And otherwise, it carried out similarly to Example 1, and obtained the conductive fiber of the triangular cross-sectional shape as shown in FIG. 6 of 220 dtex / 48 filament. A charging brush was prepared in the same manner as in Example 1.

Table 1 shows the properties of the obtained conductive fibers and brushes.
In this case, the value of R was 14.21, satisfying the expression (1), and the value of R / r was 1.6333, satisfying the expression (3). However, since there is no concave portion necessary for constructing the multileaf section, the relationship of the expression (4) does not hold, and therefore the image evaluation value is low.

Comparative Example 3 (composite of 6-leaf core sheath)
Using a nylon 6 (A) tip with a relative viscosity of 2.50 not containing carbon black and a tip of nylon 6 (B) with a relative viscosity of 1.95 containing 35% by mass of carbon black, Nylon 6 having no electrical conductivity as shown in FIG. 7 by spinning using a compound spinning device which can be fed to a rudder type melt extruder and spun a single yarn having a 6-leaf core-sheath structure. A composite single fiber having a 6-leaf core-sheath structure in which (A) is disposed in the core and nylon 6 (B) having conductivity is disposed in the sheath was obtained. This composite single fiber contained 24.50% by mass of carbon black in the entire core sheath. At this time, the draw ratio and the relaxation heat treatment time were as shown in Table 1, and the others were the same as in Example 1. As a result, a conductive composite fiber having a six-leaf cross-section of 220 dtex / 48 filaments was obtained. A charging brush was prepared in the same manner as in Example 1.

Table 1 shows the properties of the obtained conductive fibers and brushes.
In this case, the value of R satisfied the expression (1), the value of R / r satisfied the expression (3), and the value of M / N satisfied the expression (4). However, the obtained halftone image had large spots. The reason for this is that although the surface of the conductive yarn is covered with conductive nylon 6 (B), the conductive yarn and the non-conductive portion are mixed because it is a composite yarn, and the fiber end surface ( The cross section cut perpendicularly to the longitudinal direction of the fiber) is presumed to be due to a mixture of charges due to the discharge from both, and an increase in charged spots (surface potential spots).

  As is clear from the above results for Examples 1 to 6 and Comparative Examples 1 to 3 relating to the charging brush, in the case of the fully dispersed conductive yarn, 3 leaves, 4 leaves, 6 leaves rather than the round cross section of Comparative Example 1 and the like. The cross section was superior in image quality. In addition, the image quality of the four-leaf cross section was superior to that of the three leaves than the four leaves and the four leaves. Further, the image quality of the six-leaf section yarn having a small single yarn fineness of Example 6 was the highest.

  As in Comparative Example 3, even with a 6-leaf cross-sectional yarn, sufficient image quality could not be obtained with a composite conductive yarn containing a non-conductive component.

<Examples of Cleaning Brush / Comparative Example-1>
Next, examples and comparative examples of the cleaning brush used as the bias cleaner will be described.

Example 7 (6 leaves)
A master chip (35% carbon black is added to a nylon 6 chip having a relative viscosity of 2.50 (measured at a concentration of 1 g / dl and a temperature of 25 ° C. using 96% sulfuric acid as a solvent) so that the carbon black concentration is 22.0% by mass. Nylon 6 (relative viscosity 1.95) chips containing% by mass are blended and then fed to an extruder-type melt extruder, melted at a spinning temperature of 250 ° C., and a narrow hexagon as shown in FIG. The undrawn yarn was wound at a winding speed of 600 m / min while being discharged from a spinneret having 48 slit-shaped spinning holes having a radial shape and cooled by cooling air at 25 ° C.

  Next, the obtained undrawn yarn was drawn at a draw ratio of 2.6 times through a hot plate at 150 ° C., and then subjected to relaxation heat treatment for 1.9 seconds with a heater at 165 ° C. to obtain a single yarn fineness. Of 4.58 dtex and 220 dtex / 48 filaments of conductive six-leaf cross-section fibers were obtained. The fiber cross-sectional shape was as shown in FIG.

The obtained fibers were woven as a pile tape having a pile density of 150,000 pieces / (2.54 cm) ² , a pile length of 5 mm, and a fabric width of 15 mm, and then spirally wound around a metal shaft having a diameter of 6 mm to prepare a charging brush. . Thereafter, heat treatment for opening was performed with saturated steam at 100 ° C. for 5 minutes.

  Table 2 shows the properties of the obtained conductive fibers and brushes.

As shown in Table 2, since the single fiber fineness n of the fiber is 4.58 and the density ρ is 1.240, the value on the right side of the above equation (1) is 11.93. Formula (1) is R ≧ 11.93.
However, as shown in Table 2, the value of R was 14.55, which satisfied the above formula.

Moreover, as shown in Table 1, the value of R / r is 2.3355, which satisfies the formula (5), and the value of M / N is 1.2144, which satisfies the formula (6). Met.
Furthermore, according to the single fiber fineness n being 4.58 and the density ρ being 1.240, the value on the right side of the above equation (7) is 88.5, and eventually (7 ) Where S ≧ 88.5
However, as shown in Table 2, the value of S was 128.71, which satisfied Expression (7).

  As described above, the brush of Example 7 had a high cleaning evaluation value.

Examples 8-9 (6 leaves)
In Example 8, the spinning temperature was set as shown in Table 2. In Example 9, the spinning temperature and cooling air temperature were as shown in Table 1. And otherwise, it carried out similarly to Example 7, and obtained the conductive fiber. A cleaning brush was also created.

Table 2 shows the properties of the obtained conductive fibers and brushes.
In this case, as in Example 7, as shown in Table 2, the value of R satisfies the expression (1), the value of R / r satisfies the expression (5), and M The value of / N satisfies the formula (6), and the value of S satisfies the formula (7). For this reason, the cleaning evaluation value was high.

Example 10 (3 leaves)
As the spinneret, a slit-shaped one having three narrow radial shapes as shown in FIG. 1B was used, and the cooling air temperature was set as shown in Table 7. And otherwise, it carried out similarly to Example 7, and obtained the 3 leaf cross-section fiber which has the conductivity of 220 dtex / 48 filament. The fiber cross-sectional shape was as shown in FIG.

A cleaning brush was prepared in the same manner as in Example 7.
Table 2 shows the properties of the obtained conductive fibers and brushes.
Similarly in this case, as shown in Table 2, the value of R satisfies the expression (1), the value of R / r satisfies the expression (5), and the value of M / N is The expression (6) is satisfied, and the value of S satisfies the expression (7). For this reason, the cleaning evaluation value was high.

Example 11 (4 leaves)
As the spinneret, a slit-shaped one having a narrow four-sided radial shape shown in FIG. 2B was used. And otherwise, it carried out similarly to Example 10, and obtained the 4-leaf cross-section fiber which has the conductivity of 220 dtex / 48 filament. The fiber cross-sectional shape was as shown in FIG. A cleaning brush was prepared in the same manner as in Example 7.

Table 2 shows the properties of the obtained conductive fibers and brushes.
Similarly in this case, as shown in Table 2, the value of R satisfies the expression (1), the value of R / r satisfies the expression (5), and the value of M / N is The expression (6) is satisfied, and the value of S satisfies the expression (7). For this reason, the cleaning evaluation value was high.

Example 12 (6-leaf fineness)
As shown in Table 2, a spinneret having 96 slit-shaped spinning holes exhibiting a narrow hexagonal radial shape as shown in FIG. 3B is used, and the spinning temperature, cooling air temperature, draw ratio, and relaxation heat treatment time are as shown in Table 2. did. And otherwise, it carried out similarly to Example 7, and obtained the 6 leaf cross-section fiber which has the single yarn fineness of 2.29 dtex, and is 220 dtex / 96 filaments which has electroconductivity. The fiber cross-sectional shape was as shown in FIG. A cleaning brush was prepared in the same manner as in Example 7.

Table 2 shows the properties of the obtained conductive fibers and brushes.
In this case, as shown in Table 2, since the single fiber fineness n of the fiber is 2.29 and the density ρ is 1.240, the value on the right side of the above equation (1) is 8.44. After all, the formula (1) is R ≧ 8.44
However, as shown in Table 1, the value of R was 10.29, which satisfied the above formula.

Further, the value of R / r satisfies the formula (5), and the value of M / N satisfies the formula (6).
When the above conditions were used, the value on the right side of the above formula (7) was 62.6, but as shown in Table 2, the value of S was 91.07, which satisfied the formula (7). .

  As described above, the brush of Example 12 had a high cleaning evaluation value.

Comparative example 4 (round section)
A spinneret having a round slit shape was used, and the cooling air temperature, the draw ratio, and the relaxation heat treatment time were as shown in Table 2. And otherwise, it carried out similarly to Example 7, and obtained the conductive fiber of the round cross-section shape as shown in FIG. 5 of 220 dtex / 48 filament. A cleaning brush was prepared in the same manner as in Example 7.

Table 2 shows the properties of the obtained conductive fibers and brushes.
In this case, as in the case of Example 7, the formula (1) is R ≧ 11.88.
(7), S ≧ 88.5
However, as shown in Table 2, the value of R was 10.84 and the value of S was 68.11, which did not satisfy the above equation.

  For this reason, the cleaning evaluation value was low.

Comparative Example 5 (triangular section)
A spinneret having a triangular slit shape was used, and the spinning temperature and cooling air temperature were as shown in Table 2. And otherwise, it carried out similarly to Example 7, and obtained the conductive fiber of the triangular cross-section shape as shown in FIG. 6 of 220 dtex / 48 filament. A cleaning brush was prepared in the same manner as in Example 7.

Table 2 shows the properties of the obtained conductive fibers and brushes.
In this case, although the value of R satisfied the expression (1), the value of R / r did not satisfy the expression (5), and the value of S did not satisfy the expression (7). . For this reason, the cleaning evaluation value was low.

Comparative Example 6 (composite of 6-leaf core sheath)
Using a nylon 6 (A) tip with a relative viscosity of 2.50 not containing carbon black and a tip of nylon 6 (B) with a relative viscosity of 1.95 containing 35% by mass of carbon black, Nylon 6 having no electrical conductivity as shown in FIG. 7 by spinning using a compound spinning device which can be fed to a rudder type melt extruder and spun a single yarn having a 6-leaf core-sheath structure. A composite single fiber having a 6-leaf core-sheath structure in which (A) is disposed in the core and nylon 6 (B) having conductivity is disposed in the sheath was obtained. This composite single fiber contained 22.00% by mass of carbon black in the entire core sheath. At this time, the cooling air temperature, the draw ratio, and the relaxation heat treatment time were as shown in Table 2, and the others were the same as in Example 7. As a result, a conductive composite fiber having a six-leaf cross-section of 220 dtex / 48 filaments was obtained.

A cleaning brush was prepared in the same manner as in Example 7.
Table 2 shows the properties of the obtained conductive fibers and brushes.
In this case, the value of R satisfies the expression (1), the value of R / r satisfies the expression (5), the value of M / N satisfies the expression (6), and the value of S is (7 ) Was satisfied. However, the cleaning properties deteriorated as the number of printed sheets increased. In order to find the cause, the cross section of the fiber was observed, and it was found that the core of the core-sheath structure was shifted from the center of the sheath. If the center shifts in this way, the resistance value of each leaf portion of the conductive portion will be different, and the portion with a low resistance value will have the opposite polarity due to the voltage applied to the brush even if the toner is taken in. It was charged and discharged onto the intermediate transfer drum. As a result, the cleaning performance was low.

  As is clear from the above results for Examples 7 to 10 and Comparative Examples 4 to 6 regarding the cleaning brush, the brush using the fine fiber of the six-leaf cross section of Example 12 has the best cleaning stability. there were. The three-leaf cross-section yarn and the four-leaf cross-section yarn were slightly inferior to the six-leaf cross-section yarn, but the performance was remarkably superior to those of Comparative Examples 4-6.

<Examples and Comparative Examples of Cleaning Brush-2, Examples and Comparative Examples of Toner Supply Brush>
Next, examples and comparative examples of the cleaning brush used for cleaning the charging roll, and examples and comparative examples of the toner supply brush will be described.

Example 13 (6 leaves)
As shown in Table 3, the carbon black concentration was adjusted to 24.00% by mass. The cooling air temperature was set as shown in Table 3. And otherwise, it carried out similarly to Example 7, and obtained the conductive fiber.

The obtained fibers were woven as a pile tape having a pile density of 200,000 pieces / (2.54 cm) ² , a pile length of 5 mm, and a fabric width of 15 mm, and then spirally wound around a metal shaft having a diameter of 6 mm to supply a cleaning brush and toner. Each brush was created. Thereafter, heat treatment for opening was performed with saturated steam at 100 ° C. for 5 minutes.

  Table 3 shows the characteristics of the obtained conductive fibers and brushes.

Since the concentration of carbon black has changed compared to Example 7, the values on the right side of Equations (1) and (7) are the same as in Example 1 and are slightly different from those in Example 7. changed. That is, the formulas (1) and (7) are R ≧ 11.88
S ≧ 88.2
It became. However, as in Example 7, as shown in Table 3, the value of R satisfies the expression (1), the value of R / r satisfies the expression (5), and M / N The value of satisfies the formula (6), and the value of S satisfies the formula (7). Therefore, the cleaning evaluation value of the cleaning brush and the image evaluation value of the toner supply brush are high.

Example 14 (6 leaves)
As shown in Table 3, the carbon black concentration was adjusted to 24.00% by mass. The spinning temperature was set as shown in Table 3. And otherwise, it carried out similarly to Example 8, and obtained the conductive fiber. In the same manner as in Example 13, a cleaning brush and a toner supply brush were prepared.

Table 3 shows the characteristics of the obtained conductive fibers and brushes.
In this case, as in Example 8, as shown in Table 3, the value of R satisfies the expression (1), the value of R / r satisfies the expression (5), and M The value of / N satisfies the formula (6), and the value of S satisfies the formula (7). Therefore, the cleaning evaluation value of the cleaning brush and the image evaluation value of the toner supply brush are high.

Example 15 (6 leaves)
As shown in Table 3, the carbon black concentration was adjusted to 24.00% by mass. The cooling air temperature was set as shown in Table 3. And otherwise, it carried out similarly to Example 9, and obtained the conductive fiber. In the same manner as in Example 13, a cleaning brush and a toner supply brush were prepared.

Table 3 shows the characteristics of the obtained conductive fibers and brushes.
In this case, as in Example 9, as shown in Table 3, the value of R satisfies the expression (1), the value of R / r satisfies the expression (5), and M The value of / N satisfies the formula (6), and the value of S satisfies the formula (7). Therefore, the cleaning evaluation value of the cleaning brush and the image evaluation value of the toner supply brush are high.

Example 16 (three leaves)
As shown in Table 3, the carbon black concentration was adjusted to 24.00% by mass. And otherwise, it carried out similarly to Example 10, and obtained the conductive fiber. In the same manner as in Example 13, a cleaning brush and a toner supply brush were prepared.

Table 3 shows the characteristics of the obtained conductive fibers and brushes.
Also in this case, as in Example 10, as shown in Table 3, the value of R satisfies the expression (1), the value of R / r satisfies the expression (5), and M The value of / N satisfies the formula (6), and the value of S satisfies the formula (7). Therefore, the cleaning evaluation value of the cleaning brush and the image evaluation value of the toner supply brush are high.

Example 17 (4 leaves)
As shown in Table 3, the carbon black concentration was adjusted to 24.00% by mass. And otherwise, it carried out similarly to Example 11, and obtained the conductive fiber. In the same manner as in Example 13, a cleaning brush and a toner supply brush were prepared.

Table 3 shows the characteristics of the obtained conductive fibers and brushes.
Also in this case, as in Example 11, as shown in Table 3, the value of R satisfies the expression (1), the value of R / r satisfies the expression (5), and M The value of / N satisfies the formula (6), and the value of S satisfies the formula (7). Therefore, the cleaning evaluation value of the cleaning brush and the image evaluation value of the toner supply brush are high.

Comparative Example 7 (round cross section)
As shown in Table 3, the carbon black concentration was adjusted to 24.00% by mass. And otherwise, it carried out similarly to the comparative example 4, and obtained the conductive fiber. In the same manner as in Example 13, a cleaning brush and a toner supply brush were prepared.

Table 3 shows the characteristics of the obtained conductive fibers and brushes.
In this case, as in the case of Example 13, the formula (1) is R ≧ 11.88.
(7) is expressed as S ≧ 88.2.
However, as shown in Table 3, the value of R was 10.84 and the value of S was 68.11, which did not satisfy the above equation.

  For this reason, the cleaning evaluation value and the image evaluation value were low.

Comparative Example 8 (triangular cross section)
As shown in Table 3, the carbon black concentration was adjusted to 24.00% by mass. And otherwise, it carried out similarly to the comparative example 5, and obtained the conductive fiber. In the same manner as in Example 13, a cleaning brush and a toner supply brush were prepared.

Table 3 shows the characteristics of the obtained conductive fibers and brushes.
In this case, although the value of R satisfied the expression (1), the value of R / r did not satisfy the expression (5), and the value of S did not satisfy the expression (7). . For this reason, the cleaning evaluation value and the image evaluation value were low.

Comparative Example 9 (composite of 6-leaf core sheath)
As shown in Table 3, the carbon black concentration was adjusted to 24.00% by mass. And otherwise, it carried out similarly to the comparative example 6, and obtained the conductive fiber. In the same manner as in Example 13, a cleaning brush and a toner supply brush were prepared.

Table 3 shows the characteristics of the obtained conductive fibers and brushes.
In this case, the value of R satisfies the expression (1), the value of R / r satisfies the expression (5), the value of M / N satisfies the expression (6), and the value of S is (7 ) Was satisfied. However, as the cleaning brush and the toner supply brush, as the number of printed sheets increased, the printed image deteriorated as compared with Examples 13-17. This is presumed to be caused by unevenness in the resistance value of each leaf portion due to the presence of a shift between the core of the core-sheath structure and the center of the sheath. Also, as these brushes, the contribution of the tips of the fibers that make up the brushes is also large, and because the fibers have a composite structure, it is also caused by the mixture of conductive parts and non-conductive parts Inferred.

  As is clear from the above results for Examples 13 to 17 and Comparative Examples 7 to 9 regarding the cleaning brush and the toner supply brush, the cleaning performance and image quality of the example were better than those of the comparative example. It was. Further, the performance of the 6-leaf cross-section yarn was slightly higher than that of the 3-leaf cross-section yarn and 4-leaf cross-section yarn.

It is a figure which shows the shape of the slit for manufacturing the fiber of the 3 leaf cross-sectional shape of the Example of this invention, and the fiber. It is a figure which shows the shape of the slit for manufacturing the fiber of the 4-leaf cross-section shape of the Example of this invention, and the fiber. It is a figure which shows the shape of the slit for manufacturing the fiber of the 6-leaf cross-section shape of the Example of this invention, and the fiber. It is a figure explaining the cross-sectional shape of the leaf part of the fiber of the multileaf cross section based on this invention. It is a figure which shows the cross-sectional shape of the fiber of the round cross section of a comparative example. It is a figure which shows the cross-sectional shape of the fiber of the triangular cross section of a comparative example. It is a figure which shows the cross-sectional shape of the fiber of the core-sheath composite structure of a comparative example.

Claims (13)

A multifilament made of a thermoplastic resin containing conductive fine particles, and the single fiber constituting the multifilament is a fiber made of only a thermoplastic resin containing conductive fine particles, and is in the longitudinal direction of the fiber. That the cross-sectional shape cut vertically is a multi-leaf cross-sectional shape of three or more leaves, and the multi-leaf cross-sectional shape of the single fiber constituting the multifilament satisfies the following formulas (1), (2), and (3) Characteristic conductive multileaf fiber.

Where R: radius of circumscribed circle (μm), n: decitex number of single fiber, ρ: density of fiber (g / cm ³ ), π: circumference.
1.2r ≦ R ≦ 2.0r (2)
Here, r is the radius of the inscribed circle, and R is the radius of the circumscribed circle.
1.2N ≦ M ≦ 2.0N (3)
However, M is the length of the base in the leaf portion, and N is the length of the side that is parallel to the base at a position (H / 2) that is 1/2 of the height (H) of the leaf portion. 2. The conductive multileaf fiber according to claim 1, wherein the peripheral length S (μm) of the single fiber constituting the multifilament satisfies the following expression (4):

Where n is the decitex number of the single fiber, ρ is the fiber density (g / cm ³ ), and π is the circumference ratio. Instead of being multifilaments, a conductive multileaf fiber comprising monofilaments comprising the single fibers according to claim 1 or 2. 4. A brush for an electrophotographic apparatus, comprising at least a part of the conductive multilobal cross-section fiber according to any one of claims 1 to 3. A charging brush for an electrophotographic apparatus, wherein the conductive multileaf fiber according to claim 1 is used at least in part. A neutralizing brush for an electrophotographic apparatus, comprising at least a part of the electrically conductive multilobal cross-section fiber according to claim 1. A cleaning brush for an electrophotographic apparatus, comprising at least a part of the conductive multilobal cross-section fiber according to claim 2. A cleaning brush for an electrophotographic apparatus, wherein the fibers used in at least a part of the cleaning brush for an electrophotographic apparatus are multifilaments made of a thermoplastic resin containing conductive fine particles, and a single filament constituting the multifilament The fiber is a fiber made of only a thermoplastic resin containing conductive fine particles, and has a multi-leaf cross-sectional shape with three or more cross-sections cut perpendicularly to the longitudinal direction of the fiber. A cleaning brush for an electrophotographic apparatus, characterized in that the multi-leaf cross-sectional shape of a single fiber that constitutes a single-fiber satisfies the following formulas (1), (5), and (6):

Where R: radius of circumscribed circle (μm), n: decitex number of single fiber, ρ: density of fiber (g / cm ³ ), Π: Circumference ratio.
    2.0r ≦ R ≦ 3.5r (5)
Here, r is the radius of the inscribed circle, and R is the radius of the circumscribed circle.
    0.5N ≦ M ≦ 1.5N (6)
However, M is the length of the base in the leaf portion, and N is the length of the side that is parallel to the base at a position (H / 2) that is 1/2 of the height (H) of the leaf portion. 9. The cleaning brush for an electrophotographic apparatus according to claim 8, wherein the peripheral length S ([mu] m) of the single fiber constituting the multifilament is composed of a conductive multileaf fiber satisfying the following formula (4).

Where n: decitex number of single fiber, ρ: density of fiber (g / cm ³ ), Π: Circumference ratio. 10. The cleaning brush for an electrophotographic apparatus according to claim 8 or 9, wherein the cleaning brush is composed of conductive multilobal cross-section fibers that are monofilaments instead of multifilaments. A toner supply brush for an electrophotographic apparatus, wherein the fibers used in at least a part of the supply brush for an electrophotographic apparatus are multifilaments made of a thermoplastic resin containing conductive fine particles, and constitute a multifilament A single fiber is a fiber made of only a thermoplastic resin containing conductive fine particles, and has a multi-leaf cross-sectional shape in which the cross-sectional shape cut perpendicularly to the longitudinal direction of the fiber is three or more leaves, and further Toner supply for an electrophotographic apparatus, wherein the multi-leaf cross-sectional shape of a single fiber constituting the filament satisfies the following formulas (1), (5), and (6): brush.

Where R: radius of circumscribed circle (μm), n: decitex number of single fiber, ρ: density of fiber (g / cm ³ ), Π: Circumference ratio.
    2.0r ≦ R ≦ 3.5r (5)
Here, r is the radius of the inscribed circle, and R is the radius of the circumscribed circle.
    0.5N ≦ M ≦ 1.5N (6)
However, M is the length of the base in the leaf portion, and N is the length of the side that is parallel to the base at a position (H / 2) that is 1/2 of the height (H) of the leaf portion. 12. The toner supply brush for an electrophotographic apparatus according to claim 11, wherein the peripheral length S ([mu] m) of the single fiber constituting the multifilament is composed of a conductive multileaf fiber satisfying the following formula (4). .

Where n: decitex number of single fiber, ρ: density of fiber (g / cm ³ ), Π: Circumference ratio. 13. The toner supply brush for an electrophotographic apparatus according to claim 11 or 12, wherein the toner supply brush is composed of conductive multi-leaf cross-section fibers that are monofilaments instead of multifilaments.

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