JP5966499B2 - Toner manufacturing method and toner manufacturing apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for producing an electrostatic charge image developing toner used in an image forming apparatus such as an electrophotographic copying machine or printer, and relates to a toner capable of efficiently filtering and cleaning toner mother particles. The present invention relates to a manufacturing method and a toner manufacturing apparatus.

  Toner for electrostatic image development that has been widely used in electrophotography in the past is a binder resin such as a styrene / acrylate copolymer or polyester, a colorant such as carbon black or a pigment, and a charge as necessary. It has been produced by melting and kneading a mixture containing a control agent and a magnetic substance with an extruder, followed by pulverization and classification. However, the conventional pulverized toner obtained by such a kneading / pulverization method has a limit in controlling the particle size of the toner, and can substantially produce a toner having an average particle size of 10 μm or less, particularly 8 μm or less with a high yield. It is difficult and cannot be said to be sufficient to achieve the high resolution required for electrophotography.

  In recent years, as a method for improving such problems of the kneading / pulverization method, (a) toner mother particles obtained by suspending and dispersing a polymerizable monomer, a polymerization initiator, a colorant and the like in an aqueous medium and then polymerizing the toner (B) a polymer obtained by emulsifying a polymerizable monomer in an aqueous medium containing a polymerization initiator, an emulsifier and the like, and polymerizing the polymerizable monomer with stirring. Emulsion polymerization aggregation method in which toner primary particles are produced by aggregating and ripening the polymer primary particles by adding a colorant to a dispersion of primary particles, and (c) dissolving the polymer, colorant, etc. in a solvent in advance A solution suspension method for producing toner mother particles is proposed by dispersing a dispersed solution dispersion (solution dispersion of toner composition) in an aqueous medium and removing the solvent by heating or decompression. ing.

  When these wet methods are used, it is easier to control the dispersion of the raw materials than in the kneading / pulverization method, and a toner having a small particle size and a narrow particle size distribution can be obtained. be able to. In particular, the emulsion polymerization aggregation method is not only suitable for obtaining a toner having a small particle size or a narrow particle size distribution, but also has an advantage that the toner shape can be easily controlled.

  When a toner is produced by an emulsion polymerization aggregation method, a pigment, a charge control agent, or the like is added to a resin dispersion containing polymer primary particles having a particle size of about 0.05 μm to 0.5 μm obtained by emulsion polymerization, if necessary. In addition, an electrolyte or the like is further added to agglomerate to form particle aggregates of about 3 to 9 μm, and other additives are added as necessary. The particles are aged at a temperature equal to or higher than the glass transition temperature of the polymer primary particles. The particles forming the aggregate are fused together to obtain toner base particles. The toner base particles thus obtained are filtered, washed, and dried, and subjected to external addition treatment as necessary to obtain a product toner.

  In order to meet the above demands for higher resolution, a toner having a small particle size is desirable. On the other hand, as the particle size of the toner base particles produced by the wet method becomes smaller, the toner base particles are efficiently collected by filtration. It becomes difficult. Further, as the particle size of the toner base particles decreases, the surface area per unit weight of the toner base particles increases, and the toner performance is easily affected by the state of the toner base particle surface. Therefore, when filtering and washing the toner base particles, it is necessary to efficiently collect the toner base particles and effectively separate the toner base particles and impurities to avoid contamination of the toner base particle surface. is there.

  As a method of separating the toner base particles from the dispersion, a method of separating the toner base particles using a filter press device is known (see Patent Document 1). However, when toner base particles are separated using a filter press device, fine particles having a particle size smaller than that of the toner base particles are collected on the filter cloth, and the fine particles clog the filter cloth. There was a problem. The fine particles are generated from components such as a resin and a surfactant that are added to the aqueous medium in the process of generating the toner base particles but are not taken into the toner base particles. For this reason, separation of toner base particles using a filter press device requires frequent cleaning and replacement of the filter cloth, and it is difficult to efficiently separate the toner base particles.

On the other hand, as a method for separating toner mother particles, a separation method using a separation plate type centrifuge is known (see Patent Document 2). Separation of toner base particles using a separator type centrifuge does not cause the problem of clogging of the filter cloth.
However, when separating and washing the toner base particles using a separator-plate centrifuge, the toner mother particles discharged from the separator-plate centrifuge are once received in a tank, filled with washing water, diluted and reslurried. It is necessary to repeat the washing process of returning to the separation plate centrifuge again and separating the toner mother particles for many cycles. For this reason, while repeating the cleaning process, not only the impurities contained in the toner-containing slurry but also the components of the toner base particles move to the cleaning water side, and the yield of the toner base particles deteriorates. was there.

  In addition, when separating the toner base particles using a separator-type centrifuge, the toner base particles are damaged due to friction or the like by repeating the above washing process many times, and the toner base particles are removed. There was a problem of adversely affecting the quality of the product after drying.

  In addition, when separating the toner base particles using a separator plate type centrifugal separator, the water content of the toner base particles can be reduced only to about 60% (in contrast, when a filter press device is used, the water content is reduced. The rate can be reduced to about 20%), and there is a problem that a large amount of energy is consumed in the process of drying the toner base particles.

  Furthermore, since the separation plate type centrifuge described in Patent Document 2 is a “valve discharge type” separation plate type centrifugal separator, it has the following problems.

  In general, it is known that there are two types of separation plate type centrifuges, a valve discharge type and a nozzle type. As disclosed in Patent Document 2, the valve discharge type separation plate type centrifuge includes a main body portion that rotates by power of a motor or the like, and a bowl-shaped upper member and a lower portion that form the main body portion Among the members, the lower member is operated in the vertical direction using the pressure of the working fluid (water), so that the solid content (toner mother particles) accumulated in the main body portion is removed from the gap between the upper member and the lower member. It is a centrifugal separator that discharges intermittently. On the other hand, a nozzle-type separator plate centrifuge is provided with a plurality of small holes (nozzles) in the outer periphery of the main body, and the solid accumulated in the main body through the plurality of holes. This is a centrifugal separator of a type that continuously discharges the minute (toner mother particles).

As a valve discharge type separation plate centrifuge, in addition to Patent Document 2, for example, one disclosed in Patent Document 3 is known.
As a separation plate type centrifugal separator using both a valve discharge type and a nozzle type, for example, one disclosed in Patent Document 4 is known.

When a valve discharge type separation plate type centrifugal separator is used, toner mother particles accumulate near the boundary between the upper member and the lower member while the lower member is closed, and the accumulated toner mother particles generate centrifugal force. In some cases, the toner base particles are hardened by being compressed radially outward. In this case, since it becomes difficult to operate the lower member, there is a problem that the toner base particles accumulated in the main body cannot be discharged well at an arbitrary timing. Further, when the size of the solidified toner base particles is larger than the clearance that can be generated by operating the lower member, the toner base particles are blocked by the clearance even if the lower member operates well, and the toner base particles cannot be discharged. There was also a problem.
Incidentally, such a problem that occurs when a separation plate type centrifuge is used has been recognized for the first time by the present inventors.

JP 2010-224527 A Japanese Patent Laid-Open No. 2004-4652 Special table 2003-534912 JP 2001-239184 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a toner manufacturing method and a toner manufacturing apparatus capable of efficiently separating and recovering toner base particles from a toner-containing slurry. And It is another object of the present invention to provide a toner manufacturing method and a toner manufacturing apparatus capable of manufacturing a high quality toner.

Means for solving the above problems are as follows.
A method for producing toner by separating toner base particles from a toner-containing slurry obtained by a wet method,
A concentration step of concentrating the toner-containing slurry;
Separating the toner base particles from the toner-containing slurry concentrated in the concentration step using a solid-liquid separation device equipped with a filter cloth,
In the concentration step, a nozzle type separation plate type centrifugal separator is used.

An apparatus for producing toner by separating toner base particles from toner-containing slurry obtained by a wet method,
A nozzle-type separator plate centrifuge for concentrating the toner-containing slurry;
And a solid-liquid separation device provided with a filter cloth for separating the toner base particles from the toner-containing slurry concentrated by the nozzle type separation plate type centrifugal separator.

  The solid-liquid separation device provided with the filter cloth is preferably a centrifuge or a filter press device.

  The toner-containing slurry is preferably obtained by an emulsion polymerization aggregation method.

  ADVANTAGE OF THE INVENTION According to this invention, the toner manufacturing method and toner manufacturing apparatus which can isolate | separate and collect | recover a toner mother particle from a toner containing slurry can be provided. Further, it is possible to provide a toner manufacturing method and a toner manufacturing apparatus capable of manufacturing a high-quality toner.

It is a block diagram of a toner manufacturing method. It is sectional drawing of a nozzle type separation plate type centrifuge. It is sectional drawing of the modification of a nozzle type separation plate type centrifuge.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The “toner base particles” in the present invention means toner base particles formed as polymer particles in a dispersion medium such as water when a toner is produced by a wet method. The wet method is a method for producing an electrostatic charge image developing toner using a liquid dispersion medium such as water, and examples thereof include a suspension polymerization method, an emulsion polymerization aggregation method, and a dissolution suspension method. In the wet method, the toner base particles are obtained in a state of being dispersed in a dispersion medium such as water. In the present specification, such a dispersion in which toner base particles are dispersed is referred to as “toner-containing slurry”.

  The toner for developing an electrostatic charge image is produced by filtering, washing, and drying a toner-containing slurry obtained by a wet method, and performing an external addition treatment or the like as necessary. In the toner-containing slurry, not only toner mother particles but also impurities such as various by-products and contaminants derived from raw materials, surfactants, additives and the like used in the toner mother particle production process are present. For this reason, if these impurities are not properly removed in the toner base particle filtration and washing step, these impurities adhere to the surface of the toner base particles, which may adversely affect the performance of the toner.

  According to the method for producing a toner of the present invention, as will be described below, after concentrating the toner-containing slurry by a separator-plate centrifuge, the toner base particles are separated from the toner-containing slurry by a solid-liquid separator equipped with a filter cloth. Therefore, impurities in the toner-containing slurry can be effectively removed. Further, it is possible to efficiently collect the toner base particles from the toner-containing slurry.

FIG. 1 is a block diagram of a toner manufacturing method of the present invention.
As shown in FIG. 1, the toner production method of the present invention includes a concentration step of concentrating the toner-containing slurry using a separator-plate centrifuge, and a filter cloth from the toner-containing slurry concentrated in the concentration step. And a separation step of separating the toner base particles using the solid-liquid separation device.

FIG. 2 is a cross-sectional view showing an example of a separation plate type centrifuge 10 that can be used in the toner manufacturing method of the present invention.
As shown in FIG. 2, the separation plate centrifuge 10 includes a rotating shaft 12 that rotates by power such as a motor, and a main body portion 14 attached to the rotating shaft 12. A concentration chamber 16 is formed inside the main body 14. Inside the concentrating chamber 16, a plurality of separation plates 18 made of a substantially conical thin plate are arranged. The plurality of separation plates 18 are arranged at a slight interval along the axial direction of the rotary shaft 12. By using the plurality of separation plates 18, the toner-containing slurry supplied to the concentration chamber 16 can be concentrated efficiently and at high speed. Above the rotation shaft 12, an inlet pipe 20 for supplying the toner-containing slurry to the concentration chamber 16 is disposed coaxially with the rotation shaft 12. A plurality of nozzles 22 for discharging the toner-containing slurry concentrated inside the concentration chamber 16 to the outside are provided on the outer peripheral wall portion 14 a of the main body portion 14. The plurality of nozzles 22 are provided at substantially equal intervals along the circumferential direction of the outer peripheral wall portion 14 a of the main body portion 14. Further, the plurality of nozzles 22 are provided so as to penetrate through the portion of the outer peripheral wall portion 14a having the largest diameter in the radial direction. On the upper part of the main body part 14, there is provided a liquid extraction part 24 for discharging the cleaning liquid after the toner mother particles contained in the toner-containing slurry are separated by centrifugation. In addition, the separation plate type centrifugal separator having such a configuration is known, and the operation and principle thereof are disclosed in, for example, Japanese Patent Publication No. 2003-534912, Japanese Patent Application Laid-Open No. 2001-239184, Japanese Patent Publication No. 57-34023. Etc. are disclosed.

  Further, a hole 19 is provided in the vicinity of the central portion of the plurality of separation plates 18, and the toner-containing slurry rises through the hole 19. The toner-containing slurry subjected to the centrifugal force is separated between the plurality of separation plates 18 into a flow toward the center side (rotation shaft 12 side) from the hole 19 and a flow toward the outside from the hole 19. The As a result, the toner base particles contained in the toner-containing slurry can be separated at high speed and discharged from the nozzle 22.

  In the toner manufacturing method of the present embodiment, a nozzle-type separation plate centrifuge 10 is used instead of the valve discharge type. That is, instead of a method of intermittently discharging the toner-containing slurry by operating the lower portion of the main body portion 14 in the vertical direction (valve discharge type), a method of continuously discharging the toner-containing slurry from the plurality of nozzles 22 ( Nozzle-type) separation plate centrifuge 10 is used.

FIG. 3 is a cross-sectional view showing a modification of the separation plate centrifuge.
As shown in FIG. 3, a cleaning water pipe 26 that can spray cleaning water around the plurality of nozzles 22 may be provided. By providing such a washing water pipe 26, it is possible to wash the toner base particles around the nozzle 22, and more reliably prevent the toner base particles from being clogged and blocked inside the nozzle 22. Can do. A cleaning water supply pipe 28 for supplying cleaning water to the cleaning water pipe 26 is disposed on the same axis as the rotating shaft 12 above the rotary shaft 12.

  The toner-containing slurry concentrated by the separation plate centrifuge 10 is supplied to a solid-liquid separation device provided with a filter cloth.

  In the present embodiment, a filter press device is used as a solid-liquid separation device provided with a filter cloth. The filter press device is a solid-liquid separation device that can squeeze the toner-containing slurry with a filter cloth to separate and collect toner mother particles. By compressing the toner-containing slurry using a filter press, toner mother particles (dehydrated cake) having a water content of about 20% can be obtained.

  As the filter press apparatus, a pressure dehydration type, a vacuum dehydration type, a centrifugal dehydration type, and the like are known, but any type of filter press apparatus can be used. For example, it is possible to use a filter press device disclosed in JP 2007-34128 A, JP 2007-2333016 A, JP 2010-224527 A, or the like.

  After the toner-containing slurry is squeezed with a filter press device, the step of supplying washing water to the squeezed toner-containing slurry and pressing the toner-containing slurry again may be repeated. As described above, the impurities in the toner-containing slurry can be more effectively removed by repeating the supply of the washing water to the toner-containing slurry and the pressing process.

Although the example which used the filter press apparatus was shown as a solid-liquid separation apparatus provided with the filter cloth, it is also possible to use apparatuses other than this.
For example, a rotating cylindrical centrifuge can be used as a solid-liquid separation device equipped with a filter cloth. A rotating cylindrical centrifuge is a device in which a filter cloth is stretched on the inner surface of a rotatable basket, and a toner that is a solid content from a toner-containing slurry by the action of centrifugal force by rotation of the basket and filtration by the filter cloth. The mother particles can be separated.

  The rotating cylindrical centrifuge may be a vertical type in which baskets are arranged vertically or a horizontal type in which baskets are arranged horizontally. Moreover, the system in which the separated solid is discharged from above may be used, or the solid after the separation may be discharged from below. For example, a rotating cylindrical centrifuge disclosed in Japanese Patent Application Laid-Open No. 2010-224527 can be used.

  Moreover, a vacuum horizontal belt type solid-liquid separation apparatus can be used as a solid-liquid separation apparatus provided with the filter cloth. For example, a well-known vacuum horizontal belt type solid-liquid separation device such as a continuous belt filter (trade name: Eagle filter) manufactured by Sumitomo Heavy Industries, Ltd., a vacuum horizontal belt filter (trade name: ADPEC filter) manufactured by Ataca Daiki Co., Ltd., etc. Can be used.

  Moreover, a pressure filter can be used as a solid-liquid separator provided with a filter cloth. For example, a known pressure filter such as a filter dryer manufactured by Tanabe Wiltech Co., Ltd. can be used.

  The toner base particles (dehydrated cake) separated from the toner-containing slurry by the solid-liquid separation device equipped with a filter cloth are dried and subjected to external addition treatment as necessary to become toner.

For the drying, a known method used for toner drying can be used. For example, a fluidized drying method such as a vibration type fluidized drying method or a circulation type fluidized drying method, an air flow drying method, a vacuum drying method, a freeze drying method, a spray drying method Or a flash jet method can be used.
The operating conditions such as drying temperature, air volume, and degree of vacuum can be optimized as appropriate based on the Tg of the colored particles, the shape, mechanism, size, etc. of the apparatus used.

  Examples of external additives include alumina, silica, titania, zinc oxide, zirconium oxide, cerium oxide, talc, hydrotalcite and other metal oxides and hydroxides, calcium titanate, strontium titanate, barium titanate, etc. Metal titanates, nitrides such as titanium nitride and silicon nitride, carbides such as titanium carbide and silicon carbide, organic particles such as acrylic resins and melamine resins, etc., and a plurality of these can be combined.

The present invention can also be configured as a toner manufacturing apparatus.
The toner manufacturing apparatus according to the present invention includes a nozzle-type separator plate centrifuge 10 for concentrating toner-containing slurry, and toner base particles separated from the toner-containing slurry concentrated by the nozzle-type separator plate centrifuge 10. And a solid-liquid separation device provided with a filter cloth.

  In the above embodiment, an example in which the nozzle type separation plate type centrifugal separator 10 is used is shown. However, a separation plate type centrifugal separator that uses both a nozzle type and a valve discharge type as disclosed in Patent Document 4 is used. Even cases are within the scope of the present invention.

According to the toner manufacturing method and toner manufacturing apparatus of the present invention, the following effects can be obtained.
(1) In the concentration step of concentrating the toner-containing slurry with a separator-type centrifuge, fine particles having a particle size smaller than the toner base particles can be removed from the toner-containing slurry. Therefore, in the subsequent separation step, since such fine particles are not collected on the filter cloth of the solid-liquid separator equipped with the filter cloth, the filter cloth of the solid-liquid separator is clogged. Can be prevented.
(2) Toner mother particles are deposited near the boundary between the upper member and the lower member forming the main body of the centrifuge, as in the case of using a valve discharge type separation plate centrifuge. It won't harden. Therefore, the toner mother particles can be stably discharged from the main body of the centrifuge, and the electrostatic charge image developing toner can be manufactured stably and efficiently.
(3) In the step of separating the toner base particles by the solid-liquid separation device provided with the filter cloth, it is possible to repeat the step of squeezing after supplying the cleaning water to the toner base particles (cleaning step). Therefore, it is possible to manufacture a high-quality toner in which impurities are not attached to the surface of the toner base particles.
(4) Since it is not necessary to repeat the cleaning process for cleaning the toner base particles in the separator type centrifuge, the yield of the toner base particles can be improved. Further, since the toner base particles are not damaged due to friction by repeating the cleaning process, it is possible to manufacture a high quality toner.
(5) The moisture content of the toner base particles can be lowered to about 20% by a solid-liquid separator equipped with a filter cloth. Therefore, the amount of energy consumed in the step of drying the toner base particles can be reduced.

DESCRIPTION OF SYMBOLS 10 Separator plate type centrifuge 12 Rotating shaft 14a Outer peripheral wall part 14 Main part 16 Concentration chamber 18 Separation board 20 Inlet pipe 22 Nozzle 24 Liquid extraction part 26 Washing water piping 28 Washing water supply piping

Claims (8)

A method for producing toner by separating toner base particles from a toner-containing slurry obtained by a wet method,
A concentration step of concentrating the toner-containing slurry;
Separating the toner base particles from the toner-containing slurry concentrated in the concentration step using a solid-liquid separation device equipped with a filter cloth,
In the concentration step, the toner-containing slurry is concentrated using a nozzle-type separator centrifugal separator.   The method for producing toner according to claim 1, wherein the solid-liquid separation device including the filter cloth is a centrifuge.   The method for producing toner according to claim 1, wherein the solid-liquid separation device including the filter cloth is a filter press device.   The method for producing a toner according to claim 1, wherein the toner-containing slurry is obtained by an emulsion polymerization aggregation method. An apparatus for producing toner by separating toner base particles from toner-containing slurry obtained by a wet method,
A nozzle-type separator plate centrifuge for concentrating the toner-containing slurry;
And a solid-liquid separation device provided with a filter cloth for separating the toner base particles from the toner-containing slurry concentrated by the nozzle type separation plate type centrifugal separator.   The toner production apparatus according to claim 5, wherein the solid-liquid separation device including the filter cloth is a centrifuge.   The toner production apparatus according to claim 5, wherein the solid-liquid separation device provided with the filter cloth is a filter press device.   The toner production apparatus according to claim 5, wherein the toner-containing slurry is obtained by an emulsion polymerization aggregation method.

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