JP2006106236A - Method for manufacturing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing toner by which cylindrical toner particles improved in deterioration of durability and lowering of fluidity due to chipping of angular parts can be manufactured in an easy and reliable way. <P>SOLUTION: The cylindrical toner particles are manufactured through a fiber making step of forming a molten toner material into a fiber shape by extruding the toner material from a nozzle; a particle making step of producing cylindrical particles by cutting the toner material formed into the fiber shape; and an external addition and rounding-off step of carrying out external addition treatment by which an external additive is added to the surfaces of the cylindrical particles obtained at the particle making step and rounding-off treatment by which the angular parts of the cylindrical particles are made round, by applying mechanical force to the cylindrical particles after mixed with the external additive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a toner manufacturing method for manufacturing columnar toner particles having a columnar (cylindrical) outer shape.

Conventionally, as a toner manufacturing method, a toner material composed of a binder resin, a colorant (pigment), a charge control agent, a release agent (wax), etc. is mixed and melt-kneaded, and then extruded from a nozzle and stretched to correspond to the toner diameter. The fiber formed in the cross section of the above is cut into a length corresponding to the toner to produce a fine powder (corresponding to a columnar particle), and further, silica is mixed into the columnar particle using a stirring type mixer or the like, A method of using toner particles has been proposed (see Patent Document 1).
In addition, instead of the melt kneaded material of the toner raw material, a binder resin or the like dissolved in a solvent is extruded from a nozzle in the same manner as described above, and a method of adding silica to columnar particles produced by cutting is used to form toner particles. It has been proposed (see Patent Document 2).

JP-A-2-240664 Japanese Patent No. 3358015

  In the toner production methods described in Patent Documents 1 and 2, silica (fluid addition, which is a kind of external additive) is added to columnar particles prepared by cutting a melt-kneaded product or dissolved product of a toner material formed into a fiber. Since the toner particles are simply mixed to form toner particles, there is a possibility that columnar toner particles having a sharp cut-off corner or an angular shape may be produced. However, such corner-shaped columnar toner particles are inconvenient to handle because of their low fluidity, and when they are contained in a cartridge and used as a developer as schematically shown in FIG. As a result, fine particles are generated and the durability of the toner may be reduced.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to easily and reliably produce columnar toner particles with improved durability and fluidity due to corner chipping. The object is to provide a method for producing toner.

  In order to achieve the above object, the first characteristic configuration of the toner production method according to the present invention includes a particle forming step of cutting a toner raw material formed in a fibrous shape to produce columnar particles, and the particle forming step. An external addition process for binding the external additive to the surface of the columnar particles and a rounding process for rounding the corners of the columnar particles by applying a mechanical force in a state where the external additives are mixed with the columnar particles. The columnar toner particles are produced by an external additive cornering step.

That is, when a mechanical force is applied in a state where external additives are mixed with the columnar particles produced by cutting the toner raw material formed in a fibrous shape, the external additives are applied to the surface of the columnar particles by the mechanical force. Are combined, and the columnar toner particles are obtained by rounding off the corners of the columnar particles. Here, as the mechanical force, for example, a pressing force, a shearing force, an impact force, a frictional force, or the like can be applied alone or in any combination thereof. As a result, even when the corners of the columnar particles are formed into a sharp shape or an angular shape by cutting, the corners are rounded by the above-mentioned chamfering treatment, so that the fluidity is improved and the developer is used as a developer. Therefore, there is no possibility that the corners are missing and the durability is lowered. In addition, since the external addition process and the chamfering process are performed in one process, the manufacturing process is simplified.
Accordingly, there is provided a toner manufacturing method capable of easily and reliably manufacturing columnar toner particles with improved durability and fluidity due to corner chipping.

  The second characteristic configuration includes a rotating shaft provided with a stirring member on an outer peripheral portion and a casing having an inner peripheral portion located at a small gap with respect to the stirring member in the external addition chamfering step. The external addition processing and the chamfering processing are performed using a stirring processing device that stirs the processed material in the casing by the stirring member that moves as the rotating shaft rotates.

That is, when the columnar particles are put together with the external additive into the casing of the stirring processing device, the stirring particles are pushed toward the inner peripheral portion of the casing by the stirring member that moves relative to the inner peripheral portion of the casing with a small gap therebetween. Since the columnar particles and the external additive are received at the inner periphery, the mechanical force from the stirring member can be effectively applied to the columnar particles and the external additive, and the external addition treatment and the chamfering treatment are efficiently performed. Done.
Therefore, a preferred embodiment of the toner manufacturing method according to the present invention, which can efficiently perform the external addition process and the chamfering process, is provided.

The third characteristic configuration is that in the external addition chamfering step, at least one of a fluidity additive, a charge control agent, a release agent, and an abrasive is mixed as the external additive.
That is, by adding a fluidity additive externally, it is possible to increase the fluidity of the columnar toner particles to prevent the occurrence of aggregation and the like, and by adding a charge control agent, the chargeability of the columnar toner particles is increased. By adding a release agent externally, it is possible to prevent offset of the columnar toner particles to the fixing roller at the time of fixing, and by adding an abrasive to the photosensitive member. It is possible to remove deposits accumulated on the surface.
Therefore, a preferred embodiment of a toner manufacturing method that can add various functions to columnar toner particles by external addition processing is provided.

In the fourth characteristic configuration, the toner raw material contains a main charge control agent having a predetermined polarity, and in the external addition chamfering step, the external charge control agent having a polarity opposite to the main charge control agent is used. It is in the point which performs attachment processing.
That is, when the toner particles are charged by the main charge control agent contained in the toner material, the charge appears on the surface of the toner particles, but the columnar toner particles have an increased mass (particle volume) compared to the spherical toner particles. On the other hand, since the increase rate of the surface area is large, the variation width of charging due to the mass variation of each columnar toner particle tends to be large. On the other hand, when the auxiliary charge control agent is externally added to the columnar toner particles, the toner particles having a larger surface area (that is, toner particles having a larger charge amount) add more external charge control agent. The secondary charge control agent having a polarity opposite to that of the main charge control agent acts so as to cancel the charge variation due to the main charge control agent, and as a result, the variation width of the charge in the columnar toner particles is reduced.
Therefore, a preferred embodiment of a toner manufacturing method capable of reducing the variation in charging in the columnar toner particles is provided.

The fifth characteristic configuration is that, before the particle forming step, there is a fiberizing step in which the toner raw material in a molten state or a dissolved state is extruded from a nozzle to form a fiber.
That is, by extruding a molten or dissolved toner material from a nozzle, the toner material can be continuously and efficiently formed into a fiber, and a preferred embodiment of the toner production method according to the present invention is provided. Is done.

  An embodiment of a toner manufacturing method according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the toner manufacturing method of the present invention was obtained by a melt mixing step of melting and mixing toner raw materials composed of a plurality of components such as a binder resin, a colorant, and a release agent, and a melt mixing step. Obtained by a fiberizing step of extruding a molten toner raw material from a nozzle to form a fiber, a particle forming step of cutting the toner raw material formed into a fiber to produce columnar particles, and the particle forming step An external addition process for binding the external additive to the surface of the columnar particles and a chamfering process for rounding the corners of the columnar particles by applying a mechanical force in a state where the external additives are mixed with the columnar particles. Columnar toner particles are produced by the cornering step. In addition, although the cutting length is controlled in the above-mentioned particle forming process, columnar particles having a particle size distribution required for the toner are produced. If necessary, after the particle forming process or in the external addition chamfering process. A classification step may be provided later.

Next, each process will be described based on a specific apparatus configuration.
[Melt mixing process and fiberizing process]
As shown in FIG. 2, the melt-mixing step and the fiberizing step include a premixing device (for example, Hosokawa Micron Co., Ltd .: Cyclomix) 7, a hopper 1A and a rotating screw 15 as a kneading member inside. Type extruder 1, static mixer 2, flow channel structure 3 having multi-stage distribution flow channel 3 </ b> A branched from the outlet of static mixer 2, and the like, the outlet of uniaxial extruder 1 and the static mixer A gear pump 4 driven by a motor 5 is disposed between the two inlets. Note that an extrusion nozzle 6 is provided at each channel outlet of the final stage of the distribution channel 3A. Although not shown in the uniaxial extruder 1, the static mixer 2, the flow path structure 3, and the gear pump 4, the toner raw material is heated to a temperature higher than the melting point of the binder resin, for example, about 130 ° C to 240 ° C. And a heater for reducing the viscosity.

  In the above apparatus configuration, when the toner raw material is put into the uniaxial extruder 1 from the hopper 1A, it is heated by a heater to be in a molten state and fed to the outlet side while being mixed. The molten mixture of toner raw materials fed from the uniaxial extruder 1 is adjusted in pressure and extrusion amount by the gear pump 4 and then flows through the flow path in the static mixer 2 and the multistage distribution flow path 3A. Mixing is promoted, each component of the toner material is uniformly and finely dispersed, and the molten toner material is extruded downward from the plurality of nozzles 6 into a fiber shape. The plurality of fibrous bodies 12 pushed out from the nozzles 6 are stretched by hot air blown from a drawing air blowing device (not shown) and then rapidly cooled by cold air from a blower fan.

  As the static mixer 2, a known static mixer can be used. Specifically, as shown in FIG. 2, a blade having a curved surface twisted so as to form a spiral flow path. A plurality of bodies 14 (three in the example shown in FIG. 2) are provided while adjacent to each other along the flow direction of the toner material while reversing the twist angle of the spiral.

  Next, as shown in FIG. 3, a large number of fibrous bodies 12 pushed out from the nozzles 6 are placed on the belt conveyor 11 and conveyed laterally, and are allowed to cool to room temperature in the middle of conveyance, to have an appropriate viscosity. The substantially linear fibrous body 12 having the shape becomes a one-layer assembly in which the fibers are arranged in the horizontal direction, and reaches the fiber cutting device 8 in the next step. As a means for conveying the fibrous body 12, in addition to the belt conveyor 11, a gas conveying means by an air flow having a constant flow velocity and a flow direction may be used.

[Particulation process]
In the particle forming step, as shown in FIG. 3, the fiber cutting device 8 for cutting the fibrous body 12 extends in a direction perpendicular to the conveying direction of the fibrous body 12 conveyed on the belt conveyor 11. And a fibrous body between the cutting blade 10a of the rotary blade 10 and the edge 9a of the fixed blade 9 which have a rotary blade 10 having a plurality of cutting blades 10a attached to the rotary shaft and are driven to rotate by a motor (not shown). 12 is continuously supplied, and the fibrous body 12 is sequentially cut by a shearing action generated between the cutting blade 10a and the fixed blade edge 9a, and the columnar particles 13 are continuously produced. Here, the cutting length of the fibrous body 12 (the size of the columnar particles 13) can be adjusted by the ratio of the conveying speed of the fibrous body 12 and the rotational speed of the rotary blade 10.

[External cornering process]
In the external addition chamfering process, the external addition process and the chamfering process are performed using a high-speed processing type stirring processing apparatus 20 as shown in FIG. The stirring processing apparatus 20 includes a rotating shaft 22 having a plurality of stirring members 21 provided on the outer peripheral portion, and a cylindrical casing 23 having an inner peripheral portion that is positioned with a small gap with respect to the stirring member 21. The processed material in the casing 23 is stirred by the stirring member 21 that moves as the rotary shaft 22 rotates. The rotating shaft 22 is supported on one side by a bearing portion 24 and is connected to a driving portion 25 for rotation. The processed product inlet 26 is provided in the upper part on the end side of the casing 23, and the product outlet 27 is provided in the lower part of the casing 23 corresponding to the opposite end to the processed product input port 26. The casing 23 is wrapped with a jacket 28 which is a flow path for the cooling medium.

  And when the said rotating shaft 22 is seen from the position (position of FIG. 4) orthogonal to an axial direction, each stirring member 21 has the edge part position in the direction parallel to the axial direction of the rotating shaft 22 of other adjacent. Since each of the stirring members 21 is positioned inside the other stirring member 21 with respect to the position of the other stirring member 21 (the ends overlap each other), each stirring member 21 is stirred when the processed material is stirred by each stirring member 21. Deeply enters the inside of the other adjacent stirring member 21 from the end of this, and the force (impact force, etc.) of the stirring member 21 is strongly transmitted to the processing object. Further, a part of the plurality of stirring members 21 is formed on the feeding stirring member 21 a that feeds the processed material in one axial direction of the rotating shaft 22 as the rotating shaft 22 rotates. Is formed on the return stirring member 21 b that returns the processed material in the other direction of the axial direction of the rotating shaft 22 as the rotating shaft 22 rotates. Specifically, since the feed stirring member 21a and the return stirring member 21b are alternately provided along the axial direction of the rotating shaft 22, three sets are provided in total, so that the processed material is “feed → return → feed”. Compared with a case where force of “→ return → feed → return” is alternately received and only a force in one direction is received, the moving path of the processed material in the casing 23 becomes complicated and long, and the processed material receives the force of the stirring member 21. It will be even stronger. As a result of the above configuration, the external addition process and the chamfering process can be performed quickly.

  FIG. 6 schematically shows a state in which the columnar toner particles 13A are produced by performing the external addition process and the chamfering process on the columnar particles 13 (for example, columnar particles) in the external addition chamfering step. In the chamfering process, the sharp corners of the columnar particles 13 are scraped to generate fine powder. However, since the fine powder is also bonded to the surface of the columnar particles 13 in the same process as the external addition process, generation of fine toner particles is suppressed. . In the external addition process, the external additive G adheres to the surface (outer peripheral surface and end surface) of the columnar particles 13, but particularly adheres more to the outer peripheral surface than the end surface when the columnar particles 13 are long. FIG. 6 shows the case where the external additive G is bound to the surface of the columnar particle 13 that has been subjected to the chamfering process for the sake of clarity, but the columnar particle 13 to which the external additive G is bound is shown. When the chamfering process is performed (in this case, the fine powder with the external additive G generated by the chamfering process can be recombined with the columnar particles 13 by the external addition process), the chamfering process and the external addition process are performed simultaneously in parallel. Various processing states are conceivable, for example, when performing automatically.

  In the external addition chamfering step, as the external additive G, one or more of a fluidity additive, a charge control agent, a release agent, and an abrasive are mixed. Specific examples of the material are as follows. As the fluidity additive, silica, alumina, titania or the like having a particle size of about 7 nm to 50 nm is used. As the charge control agent, colored zinc salicylate is used for black toner, and colorless lecithin is used for color toner. The release agent is for preventing an offset to a fixing roll and the like, and fluorine fine particles having a particle diameter of about 50 nm to 500 nm, emulsion polymerization fine particles, and various waxes (for example, carnauba wax) are used. The abrasive is for removing deposits on the photoreceptor, and alumina, cerium oxide, strontium titanate, or the like is used.

By the way, when a charge control agent is included in the toner raw material, an external addition process is performed in the external addition chamfering step using a sub-charge control agent whose polarity is opposite to that of the main charge control agent contained in the toner raw material. This is effective for reducing the variation in charging of the columnar toner particles. This will be specifically described below.
When the columnar toner particles 13A are charged by the main charge control agent contained in the toner raw material, the charge appears on the surface of the columnar toner particles. However, the columnar toner particles are more sensitive to the increase in mass than the spherical toner particles. Since the increase rate of the surface area is large, the variation width of the charge due to the mass variation of the columnar toner particles tends to be large. For example, in the case of a spherical toner, when the mass is doubled, the surface area is 2 ^2/3 times (about 1.59 times), whereas in the case of columnar toner particles, if a fibrous body having the same diameter is cut, the mass is increased. When it is doubled, the particle length is doubled and the surface area is doubled (however, the area of the cut surface of the particle is ignored).

  FIG. 7A shows an example of the distribution of the charge amount of the columnar toner particles by the negative main charge control agent. Here, when the positive charge control agent is externally added to the columnar toner particles, the column charge toner particles having a larger positive charge amount (that is, the columnar toner particles having a larger mass and a larger surface area) have a smaller charge amount. Since many external additives are added, the sub-charge control agent having a polarity opposite to that of the main charge control agent acts so as to cancel the variation in charge due to the main charge control agent. As a result, as shown in FIG. The variation range of charge (negative polarity) in the toner particles is reduced. In FIG. 7, the horizontal axis represents the ratio of the charge amount to the particle diameter (femtocoulomb / 10 μm), and the vertical axis represents the number of particles. Further, this charging characteristic can be measured by Hosokawa Micron Co., Ltd .: Espert Analyzer.

[Another embodiment]
In the above embodiment, the toner material in the molten state is formed in a fiber shape in the miniaturization step, but in addition to this, the toner material in a dissolved state in which a binder resin or the like is dissolved in a solvent is extruded from the nozzle to form a fiber shape. May be.

  In the above embodiment, in the external addition chamfering process, the external addition process and the chamfering process are simultaneously performed using the agitation processing apparatus 20 as shown in FIG. A quality type mixer, for example, a mechanofusion system manufactured by Hosokawa Micron Co., Ltd. (this apparatus mainly applies a pressing force or a shearing force), a cyclomix, or the like may be used.

  In the above embodiment, the rotary blade type fiber cutting device 8 is used in the particle forming step, but various other cutting devices and various grinding devices (for example, a pin mill) can be used.

  Next, examples of the toner manufacturing method according to the present invention will be described.

(Example of black toner)
100 parts by weight of a polyester resin (Tg: 64 ° C., starting temperature (measured by a flow tester manufactured by Shimadzu Corporation): 119 ° C.), 10 parts by weight of carbon black, 3 parts by weight of zinc salicylate as a negative main charge control agent, and Then, 5 parts by weight of carnauba wax as a release agent is premixed by the premixing device 7, and then supplied to the uniaxial extruder 1 to be melted and pressure-adjusted by the gear pump 4 (about 4. in the latter stage of the gear pump). 2 MPa) at a temperature of 150 ° C. and extruded to the stationary mixer 2. Then, after being melt-mixed in the static mixer 2, it was stretched to a wire diameter of 5.0 μm with hot air while being extruded from a nozzle 6 having a pore diameter of 300 μm, and then cooled to obtain fine particle precursor fibers. The fiber generation rate at this time was calculated to be about 40 m / sec from the extrusion amount and the fiber diameter.

  Next, the fine particle precursor fiber was pulverized by a classifier built-in type pulverizer (for example, ACM pulverizer manufactured by Hosokawa Micron Corporation). Columnar particles having a particle size distribution in which the ratio of particles of 12 μm or more on the volume basis was 1.4%, the ratio of particles of 16 μm or more was 0%, and the ratio of fine particles of less than 5 μm on the number basis was 11.2% were obtained.

  An observation result of the columnar particles by SEM is shown in FIG. 8, and it can be confirmed that protrusions and burrs are formed at the corners of the columnar particles by cutting. In addition, it was confirmed that the charging characteristics of the columnar particles showed a tendency similar to that shown in FIG.

  Next, 100 parts by weight of the toner particles, 0.01 parts by weight of zinc stearate (average particle size 0.3 μm) as a negative charge control agent, and magnesium stearate (average particle size of 1. .mu.m) as a positive charge control agent. 2 μm) 0.01 parts by weight, 0.75 parts by weight of silica 1 (particle diameter 20 nm calculated from specific surface area) and 0.75 parts by weight of silica 2 (particle diameter 50 nm calculated from specific surface area) as fluid additives, and 1.20 parts by weight of alumina (average particle size: 0.97 μm) as an abrasive is stirred and mixed by the high-speed processing type stirring device 20 with a power applied to the raw material particles per unit weight of 0.28 kw / h, A developer was obtained. The same amount of zinc stearate and magnesium stearate is added, but positive polarity magnesium stearate has a higher charging capacity per unit weight, so the polarity of the external charge control agent added externally is higher. As a positive polarity. Further, the zinc stearate and magnesium stearate have a function as a lubricant as well as a charge control agent.

  FIG. 9 shows the result of SEM observation of the columnar toner particles. The protrusions and burrs formed at the corners of the columnar particles after cutting are removed, and external additives such as silica are added to the surface of the columnar particles. It can be confirmed that they are combined. In addition, it was confirmed that the charging characteristics of the present columnar toner particles showed the same tendency as in FIG.

  Then, the developer composed of the columnar toner particles obtained as described above was subjected to image evaluation using an image device (printer LP-2500 manufactured by Seiko Epson Corporation). As a result, the obtained image had a high and stable image density, a good density control (gradation), a high resolution, and a sharp image. Moreover, there were no background stains or dust at the time of transfer. Further, no filming of toner particles on the developing roll or the photoreceptor surface was observed after the 10,000 sheet printing test.

  The method for producing a toner according to the present invention can be suitably used for producing columnar toner particles having unique characteristics as compared with ordinary spherical toner particles.

Process diagram of toner production method according to the present invention The figure which shows the apparatus structure of the melt mixing process and fiberization process of this invention The figure which shows the apparatus structure of the granulation process of this invention The figure which shows the apparatus structure of the external addition chamfering process of this invention Diagram for explaining the defects of the prior art Schematic diagram illustrating chamfering and external addition processing by the toner manufacturing method of the present invention The graph explaining the charge control state of the columnar toner particles according to the present invention Photograph showing columnar particles after granulation Photo showing columnar toner particles after external chamfering treatment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Single axis | shaft type extruder 2 Static mixer 3 Flow path structure 3A Flow path 4 Gear pump 5 Motor 6 Nozzle 7 Preliminary mixing device 8 Fiber cutting device 9 Fixed blade 9a Fixed blade edge 10 Rotary blade 10a Cutting blade 11 Belt conveyor 12 Fibrous Body 13 Columnar particle 13A Columnar toner particle 14 Blade body 15 Kneading member 20 Stirring treatment device 21 Stirring member 22 Rotating shaft 23 Casing 24 Bearing portion 25 Drive portion 26 Processed material inlet 27 Product outlet 28 Jacket G External additive

Claims (5)

A particle forming step of cutting columnar particles by cutting a fiber raw material,
A mechanical force is applied in a state where an external additive is mixed with the columnar particles obtained in the particle forming step, and an external treatment for binding the external additive to the surface of the columnar particles and corners of the columnar particles are performed. A toner production method for producing columnar toner particles by an external addition chamfering process for rounding a chamfer.   In the external addition chamfering step, a rotating shaft provided with a stirring member on an outer peripheral portion and a casing having an inner peripheral portion positioned with a small gap with respect to the stirring member are provided to rotate the rotating shaft. The toner manufacturing method according to claim 1, wherein the external addition process and the chamfering process are performed using an agitation processing apparatus that agitates the processed material in the casing by the agitation member that moves with the agitation member.   3. The toner manufacturing method according to claim 1, wherein in the external addition chamfering step, at least one of a fluidity additive, a charge control agent, a release agent, and an abrasive is mixed as the external additive. The toner material contains a main charge control agent having a predetermined polarity;
The toner manufacturing method according to claim 3, wherein, in the external addition chamfering step, the external addition process is performed using a sub-charge control agent having a polarity opposite to that of the main charge control agent. 5. The method for producing a toner according to claim 1, further comprising a fiberizing step in which the toner raw material in a molten state or a dissolved state is extruded from a nozzle to form a fiber before the particle forming step.