JP4661488B2 - Electrophotographic toner manufacturing equipment - Google Patents

Description

  The present invention relates to a method for producing an electrophotographic toner.

  In the electrophotographic method, an electrostatic latent image formed on a latent image carrier (photoconductor) is developed with toner containing a colorant, and the resulting toner image is transferred onto a transfer member, which is then heated. The latent image carrier is cleaned to form an electrostatic latent image again. The dry developer used in such electrophotography is a one-component developer using a toner in which a colorant or the like is blended in a binder resin, and a two-component developer in which a carrier is mixed with the toner. Broadly divided. One-component developer uses magnetic powder and is conveyed to the latent image carrier by magnetic force and developed, and the non-magnetic developer is charged to the latent image carrier by charging such as a charging roll and developed. It can be classified into magnetic one component. Since the latter half of the 1980s, the market for electrophotography has been strongly demanded for miniaturization and high functionality with the key to digitization, and in particular, high-quality prints close to high-quality printing and silver halide photography are desired for full color image quality.

  Digitization processing is indispensable as a means for achieving high image quality, and the effect of digitization related to such image quality is that complex image processing can be performed at high speed. This makes it possible to control characters and photographic images separately, and the reproducibility of both qualities is greatly improved compared to analog technology. In particular, for photographic images, gradation correction and color correction are possible, and this is advantageous over analog in terms of gradation characteristics, definition, sharpness, color reproduction, and graininess. However, on the other hand, it is necessary to faithfully form a latent image created by an optical system as an image output, and as a toner, an activity aimed at faithful reproduction has been accelerated as the particle diameter is increasingly reduced. However, in the conventional pulverization classification method, the energy consumption increases as the particle size is reduced, and even if the toner diameter is simply reduced, the presence of the fine powder side toner may cause contamination of the carrier and the photoreceptor and toner scattering. The problem became significant, and it was difficult to achieve high image quality and high reliability at the same time.

  In view of speeding up and energy saving of these machines, further low temperature fixability is required. Also in this regard, it is difficult to ensure low temperature fixability from the viewpoint of “grindability” by the conventional grinding classification method. Therefore, as a method for efficiently producing this small particle size toner, an emulsion polymerization aggregation method (aggregation / melting method; see, for example, Patent Document 1 to Patent Document 3) and suspension polymerization method (for example, Patent Document 4 to Patent Document 6). And wet methods such as in-liquid drying methods (see, for example, Patent Document 7 to Patent Document 10). In particular, the emulsion polymerization aggregation method is a particularly excellent method for sharpening the particle size distribution of the toner.

  The single mother particles obtained by these wet processes cannot satisfy the requirements as a developer in terms of properties such as toner fluidity, transferability, and chargeability. Therefore, for the purpose of these improvements, inorganic oxide fine powder and the like have been conventionally mixed as an external additive (hereinafter referred to as “external additive”). The state of adhesion of these external additive particles to the surface of the toner particles greatly affects not only the chargeability of the toner particles but also the image quality. In particular, the free component of the external additive not attached to the toner is not preferable because it causes problems such as filming and comet. Therefore, it is very important to uniformly optimize the adhesion state of the external additive particles to the toner particle surface in the toner manufacturing process. In addition, external additives to be added tend to increase due to an increase in surface area due to the recent reduction in toner particle size, and as a result, free components of external additives also tend to increase.

  In order to solve these problems, Patent Document 11 proposes a stirrer having rotating blades in which the cross-sectional area of the tip portion of 2/3 or more from the rotation center of the mixer occupies 0.5 or more of the total cross-sectional area.

  Patent Document 12 proposes a method of mixing at a peripheral speed of 40 to 150 m / s using a spherical processing device having a smooth inner wall surface, for example, a Q-type mixer as shown in FIG.

Japanese Patent Laid-Open No. 63-282275 JP-A-6-250439 JP-A-10-26842 Japanese Patent Publication No. 36-10231 Japanese Patent Publication No. 43-10799 Japanese Patent Publication No. 51-14895 JP-A-50-120632 JP 63-25664 A Japanese Patent Laid-Open No. 5-127422 JP-A-8-179556 JP-A-9-150048 JP 2002-351141 A

  However, in the method using the mixing energy in the external addition step as in these methods, since different types of external additives are mixed at the same time, it is not possible to adjust the free external additives of the respective external additives to a desired level. In addition to being very difficult, there are problems such as deterioration of powder fluidity due to exposure of the wax component to the toner surface due to high share.

  The present invention has been made in order to improve the above-mentioned problems, and it is difficult to industrially use, and to efficiently and stably remove free external additives that cause a reduction in product image quality. It is an object of the present invention to provide an electrophotographic toner manufacturing method that has been made possible.

  As a result of intensive studies on the industrial removal method of free external additives, the present inventor has made it possible to solve the above problems. That is, the configuration of the present invention is as follows.

(1) a binder resin, a colorant toner production apparatus for electrophotography having external addition toner obtained by adding and mixing an external additive to toner base particles made of, dispersing a resin particle dispersion, a colorant And agitation particles for mixing and agglomerating the aggregated particles by mixing the resin particles and the pigment particles to form aggregated particles, and then mixing the aggregated particles. A mixing device that mixes an external additive with toner base particles, and a cyclone device that has an upper part for discharging fine powder of unattached external additive and a lower part for discharging external additive-attached external toner. The ratio of the diameter Dc of the upper part of the cyclone device and the diameter De of the fine powder outlet of the lower part of the cyclone device is 2.0 ≦ Dc / De ≦ 3.5 when the air volume is 20 to 45 m ³ / min. An electrophotographic toner manufacturing apparatus .

(2) In the above (1), the fine powder removal amount finally captured by the cyclone device is 0.01 to 5% by weight with respect to the pre-toner particle input amount after the external addition step by the mixing device. The electrophotographic toner manufacturing apparatus according to claim 1 .

  According to the present invention, it is possible to efficiently remove the free external additive in the toner particles having a smaller diameter produced by the emulsion polymerization aggregation method without impairing the toner performance.

  Hereinafter, the present invention will be described in more detail with reference to embodiments.

  The method for producing an electrophotographic toner in the present invention is not particularly limited except that a step having a fine powder removing means is provided after the external addition step. It can be done according to this. As a toner used in the embodiment, for example, a method proposed in Japanese Patent Application Laid-Open No. 2000-131876 may be used. In this method, a resin dispersion using an ionic surfactant and a pigment dispersed in an ionic surfactant of opposite polarity are mixed to form hetero-aggregation to form toner-aggregated particles, and then the resin The toner is produced by fusing and integrating the aggregates by heating above the glass transition point, washing, drying, external mixing, and dry sieving. In this method, the toner shape can be controlled from an indeterminate shape to a spherical shape by selecting a heating temperature condition. Even if the polarities of the pigment and the resin particle are the same, a similar aggregate can be formed by adding a surfactant having an opposite polarity.

  Further, for example, before the aggregated particle dispersion is heated to fuse the aggregated particles, another fine particle dispersion is added and mixed to adhere the fine particles to the surface of the original aggregated particles, and then the resin glass. The layer structure from the surface to the inside of the toner may be controlled by adopting a method of fusing by heating above the transition point (Tg). By this method, it is possible to coat the toner surface with a resin, coat with a charge control agent, or dispose wax or pigment near the toner surface.

  The thermoplastic binder resin of the toner produced in the present embodiment includes styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, acrylic Esters having a vinyl group such as 2-ethylhexyl acid, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile; vinylmethyl Vinyl ethers such as ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; monomers such as polyolefins such as ethylene, propylene and butadiene Polymers, copolymers of these two or more, or mixtures thereof, epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, etc., non-vinyl condensation resins, or these And a mixture of the vinyl resin and a graft polymer obtained by polymerizing a vinyl monomer in the presence of these.

  When using a vinyl monomer, for example, an emulsion polymerization or seed polymerization can be performed using an ionic surfactant or the like to prepare a resin particle dispersion. When using other resins, for example, Dissolve the resin in a solvent that is oily and has a relatively low solubility in water. Disperse the fine particles in water with a disperser such as a homogenizer in the presence of an ionic surfactant or polymer electrolyte in water, and then heat or reduce the pressure. Thus, a desired resin dispersion can be prepared by evaporating the solvent.

  The thermoplastic binder resin can stably produce fine particles obtained by emulsion polymerization or the like, for example, by blending a dissociable vinyl monomer or the like. Examples of dissociative vinyl monomers include acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, vinyl sulfonic acid, ethyleneimine, vinylpyridine, vinylamine and other polymer acids and polymer base materials. Any of the following monomers can be used, but a polymer acid is preferred because of the ease of polymer formation reaction, and further, acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, etc. A dissociable vinyl monomer having a carboxyl group is particularly effective for controlling the degree of polymerization and the glass transition point.

  Examples of mold release agents include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; softening points upon heating of oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid amide, etc. Fatty acid amides having plant; plant wax having softening point by heating such as ester wax, carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, etc .; animal having softening point by heating such as beeswax Waxes such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc .; mineral waxes having a softening point upon heating; petroleum waxes having a softening point upon heating; It can be used sex and the like.

  These waxes are, for example, homogenizers and pressure discharge type dispersers that can be dispersed in water together with ionic surfactants, polymer electrolytes such as polymer acids and polymer bases, and heated to the melting point or higher and impart strong shear. And a dispersion of particles having a particle size of 1 μm or less can be prepared.

  Colorants include carbon black, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, balkan orange, watch young red, permanent red, brilliantamine 3B, brilliantamine 6B, and dapon. Oil Red, Pyrazolone Red, Resor Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, etc. Or acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindico, geo One or two types of various dyes such as sazine, thiazine, azomethine, indico, thioindico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazine, thiazole, and xanthene A mixture of more than one species can be used.

  As the internal additive, a magnetic material such as a metal such as ferrite, magnetite, reduced iron, cobalt, nickel, manganese, an alloy thereof, or a compound containing the metal can be used.

  As the charge control agent, various commonly used charge control agents such as quaternary ammonium salts, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments can be used. In order to control the ionic strength that affects the stability at the time of aggregation and fusion integration and to reduce wastewater contamination, a charge control agent that is difficult to dissolve in water is preferable.

  Surfactants used in emulsion production, seed polymerization, pigment dispersion, resin particles, release agent dispersion, aggregation, or stabilization thereof in the toner production process include sulfate ester, sulfonate, and phosphate ester types. Anionic surfactants such as soaps; Cationic surfactants such as amine salts and quaternary ammonium salts; Nonionic interfaces such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols It is also effective to use an active agent in combination.

  Dispersing means in these toner production methods include general dispersion such as a rotary shear type homogenizer, a ball mill having media, a sand mill, a dyno mill, a DCP mill, a spike mill, and a forced collision type optimizer (manufactured by Sugino Machine Co., Ltd.). You can use the machine.

  For agglomeration, a general jacketed stirring tank or the like is used. As stirring blades, paddle blades, anchor blades, turbine blades, fuudler blades, full-zone stirring blades (manufactured by Shinko Pantech Co., Ltd.), Max Blend stirring blades (manufactured by Sumitomo Heavy Industries, Ltd.), bend leaf stirring blades (Hachiko Industry Co., Ltd.) Manufactured) and the like. Further, as the material of the stirring tank wall, stainless steel (SUS304, SUS316, etc.), buffed and / or electrolytically polished, glass-lined or Teflon (registered trademark) -lined, etc. are preferably used. It is done. Moreover, you may install a baffle in a tank. For fusion, a similar jacketed stirring tank or the like is preferably used.

  Coarse particles may be removed from the fused toner slurry by, for example, a circular vibrating sieve or a filter bag.

  The toner slurry can be washed by, for example, a method of repeatedly filtering the slurry and returning it to water, a method of creating a cake layer with a filter press, a belt filter, or the like and forcing water to pass through the cake layer. A combined method or the like is used, and in some cases, the toner may be put into an acid or (and) alkali solution and washed in the middle of washing.

  In the drying process, a general dryer such as a wind dryer such as a flash jet dryer, a vacuum dryer, a freeze vacuum dryer, or a shelf dryer can be used. Depending on the case, the treatment may be performed a plurality of times with a dryer, or multistage drying may be performed with different dryers. Moreover, it is preferable to carry out drying after filtering with a filter press, a belt filter or the like, then reducing the moisture content by air blowing or the like, and further crushing.

  External addition mixing can be performed by, for example, a V-type blender, a Henschel mixer, a Q-type mixer, a cyclomix, or the like.

  For the dry sieving, a wind sieving machine, a circular vibrating sieve, a gyro shifter, an ultrasonic vibrating sieve, a turbo screener, or the like is used, and a mesh having an opening of 25 to 300 μm is preferably used.

  The thus obtained toner colored resin particles preferably have a volume average particle size of 3 to 8 μm, and more preferably 4.5 to 7 μm. If it is smaller than 3 μm, the fluidity of the toner is remarkably deteriorated, toner clogging in the apparatus and image quality defects due to adhesion are likely to occur, and if it is larger than 8 μm, fine line reproducibility and graininess are deteriorated.

  As the external additive, at least one kind of fine particles, for example, known external additives such as inorganic fine particles and organic fine particles can be used. Examples of external additives include inorganic fine particles such as silica, titania, alumina, cerium oxide, strontium titanate, calcium carbonate, magnesium carbonate, and calcium phosphate, fluorine-containing resin fine particles, silica-containing resin fine particles, and nitrogen-containing resin fine particles. Examples include organic resin fine particles, and spherical fine particles having a shape factor of about 100 to 130 are preferable, and spherical inorganic fine particles are more preferable. Silica is preferable as the spherical inorganic fine particles. Further, spherical inorganic fine particles such as silica and plate-like inorganic fine particles such as titania may be used in combination, or a plurality of them may be added. Further, the surface of the external additive may be subjected to a surface treatment according to the purpose. Examples of the surface treatment agent include a silane compound, a silane coupling agent, and a silicone oil for performing a hydrophobic treatment. The external additive may be dispersed in an ionic surfactant, a polymer acid, a polymer base or the like and added wet.

  The particle size of the external additive is preferably 5 to 60 nm, and more preferably 15 to 50 nm. If the thickness is less than 5 nm, the external additive is difficult to disperse, and image quality defects due to aggregates of the external additive are likely to occur. Further, an external additive having a large particle diameter of 60 to 500 nm may be used in combination.

  Next, the fine powder removing means used in the present embodiment will be described in detail. As the fine powder removing means used in the present embodiment, a conventionally known classifier such as an elbow jet classifier, ATP, TTSP, or cyclone is used.

  Further, it is desirable that the amount of fine powder removed finally captured by the fine powder removing means be in the range of 0.01 to 5% with respect to the amount of pre-toner particles introduced after the external addition step, It is desirable to set it in the range of 03 to 3%.

  When the fine powder removal amount is less than 0.01%, the removal of the free external additive becomes insufficient, and as a result, for example, filming of the photoreceptor occurs. On the other hand, when it exceeds 5%, for example, an external additive that is difficult to adhere to the toner, such as cerium oxide, is removed, and the function of the external additive, for example, chargeability is impaired.

  In addition, when the fine powder removal amount is 0.03% or more, the free external additive can be sufficiently removed even if a classifier with low classification accuracy is used. Further, by setting the removal amount of fine powder to 3% or less, the loss amount of the product toner can be reduced while sufficiently achieving the object of the present invention.

  The classifier used for fine powder removal is particularly suitable for removing small particle size particles such as free external additives because the cyclone device tends to reduce the separated particle size.

  As is known in the art, the cyclone can adjust the cut point by changing the speed of the incoming air and the dimensions of each part. Thus, the fine powder removal amount can be controlled by adjusting the cut point to the optimum value.

  FIG. 1 shows a schematic diagram of a cyclone classification system including a cyclone device preferably used in the present invention.

  The material toner supplier 1 is connected to the inlet 32 of the cyclone 3 via a pipe 17, while the air inlet 2 is also connected to the pipe 17. A product hopper 4 is connected to a toner discharge port below the cyclone 3, and an air knocker 5 that is operated during collection is provided in the product hopper 4. In addition, a butterfly valve 7 is provided at the lower discharge port of the product hopper 4, and a product collection container 8 is provided via the butterfly valve 7 and the air filter 6. Further, the product collection container 8 is placed on a lifting device 9 installed on the floor 40. On the other hand, the fine powder outlet 34 of the cyclone 3 is connected to the bag filter 10 via a pipe 36, and the lower part of the bag filter 10 is connected to the fine powder collection container 11 via a valve 20. Further, the bag filter 10 is connected to a safety filter 12, and the safety filter 12 is connected to a blower 15 via a pressure gauge 13, an air volume meter 14, and an air volume control valve 16.

  Next, the operation of the fine powder removing means of the cyclone classification system shown in FIG. 1 will be described.

  The raw material toner is supplied from the supply device 1, and the air flow rate adjusting valve 16 is adjusted while being monitored by the pressure gauge 13 and the air flow meter 14, and is placed on the air flow from the air inlet 2 by the blower 15. Through the inlet 32 and into the cyclone 3. The toner classified by the airflow inside the cyclone 3 is collected by the product hopper 4, and the fine powder is collected by the bag filter 10 through the fine powder discharge port 34 of the cyclone 3 and the pipe 36. A butterfly valve 7 is installed under the product hopper 4, and the butterfly valve 7 is always closed during supply. The butterfly valve 7 is preferably a non-sliding valve such as a positive freight valve from the viewpoint of preventing the generation of coarse powder. When a predetermined amount of toner is collected, the supply is stopped, and the product toner stored in the product hopper 4 is collected in the collection container 8 by opening the butterfly valve 7. At the time of recovery, the discharge time can be shortened by operating the air knocker 5 or operating the filter backwash pulse air of the deaeration filter 6.

  As shown in FIG. 2, the cyclone 3 is supplied with raw toner from the inlet 32 and rides on the airflow (white arrow indicating the rotation direction) flowing in along with the raw toner, and the classified toner particles are discharged from the toner discharge port 35. On the other hand, the fine powder soared by the centrifugal force due to the wind speed of the air current is discharged through the fine powder discharge port 34.

  As shown in FIG. 5, an example of a method for producing an electrophotographic toner of the present embodiment is to prepare pre-toner particles by an emulsion polymerization aggregation method, and add the above-mentioned external additives through washing and drying processes. After the external addition process and the fine powder removal process, the product toner is filled through a sieving process for selecting a desired toner particle size. That is, the present invention is characterized in that the fine powder removing step described above is provided between the external addition step and the sieving step as compared with the conventional method for producing a toner for electrophotography shown in FIG. FIG. 5 is an example showing the flow of the toner production method of the present invention. However, the present invention is not limited as long as it has a fine powder removing means after the external addition process. For example, the fine powder removal process after sieving is performed. In addition, fine powder removing means may be provided in the line of the sieving step.

  Next, the structure of a suitable cyclone 3 included in the fine powder removing means described above will be described with reference to FIG.

The sum of the wind speed of the air flowing from the inlet 32, and the ratio of the diameter De of the diameter Dc and fines outlet of the cyclone top, further cyclone upper length H ₁ and cyclone lower length H ₂ having a diameter a That is, it is unnecessary while increasing the yield of recovered toner by optimizing the ratio of the dimension H from the end of the cyclone toner outlet to the end of the fine powder outlet 34 with respect to the longitudinal dimension of the cyclone. The removal of an external additive can be suppressed.

In the present embodiment, the air volume is 20 to 45 m ³ / min (normal pressure), and the ratio of Dc: De is 2.0 ≦ Dc / De ≦ 3.5, preferably 2.5 ≦ Dc / De. ≦ 3.0, while the ratio of {H ₁ + H ₂ } / H is 1.15 ≦ (H ₁ + H ₂ ) /H≦1.30, preferably 1.20 to 1.25. .

When the ratio of Dc: De is less than the above lower limit, the fine powder cannot be sufficiently removed. On the other hand, when the ratio exceeds the above upper limit, the swirling airflow is not stable and the fine powder removing performance varies. When the value of {H ₁ + H ₂ } / H is less than the above lower limit, the toner having a particle size other than the desired fine powder is short-passed, resulting in a decrease in product yield, while when the value exceeds the above upper limit. As a result, the efficiency of removing fine particles from the toner particles decreases.

  FIG. 4 shows a partial schematic view of a cyclone classification system including a cyclone device preferably used in the present invention. Since the configuration other than the configuration shown in FIG. 4 is the same as that in FIG. 1, the illustration thereof is omitted.

  In FIG. 4, the product hopper 4 is connected to the cyclone 3, the product hoppers 4 are stacked in two stages, each is connected by a butterfly valve 7, and the two product hoppers 4 are connected by piping via a three-way valve 18, Further, the lower product hopper 4 and the collection container are connected by piping through a three-way valve 18. In the above configuration, the three-way valve 18 replaces the role of the air knocker 5 and the air filter 6 of FIG.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples. In the following description, “parts” means “parts by weight” unless otherwise specified.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail more specifically, this invention is not limited to a following example, unless the summary is exceeded.

  Each measurement shown by an Example and a comparative example was performed with the following method.

<Particle size distribution (volume average particle size (D50))>
A Coulter Multisizer II (Beckman Coulter, Inc.) is used, and an ISOTON-II (Beckman Coulter, Inc.) is used as the electrolyte. As a measurement method, 005 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant. This is added to 100 to 150 ml of the electrolytic solution. The electrolyte solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution of particles of 2 to 60 μm is measured using the Coulter counter TA-II type with an aperture diameter of 100 μm. Determine the volume average particle size. The number of particles to be measured was 50,000.

<Free inorganic fine particle ratio, inorganic fine particle recovery ratio>
2 g of toner base particles are added to 40 ml of an aqueous solution containing 0.2% surfactant (polyoxyethylene (10) octylphenyl ether), and stirred for 10 seconds with a spatula. Next, the dispersion is centrifuged in a centrifuge at 3000 rpm for 2 minutes, and the supernatant is removed. Thereafter, ion-exchanged water is added and dispersed again. The dispersion is filtered through a filter paper, and the supernatant is left to stand at room temperature for one day and dried. The dried product is compression-molded, measured by fluorescent X-rays, and inorganic. The NET strength A of the constituent element of the fine particles (for example, Si when the inorganic fine particles are silica) is measured. Further, the toner is compression-molded as it is, and the NET intensity B of the constituent element of the inorganic fine particles (for example, Si when the spherical fine particles are silica) is measured using a fluorescent X-ray measuring instrument: XRF1500 (manufactured by Shimadzu Corporation). Further, if necessary, the toner base particles are also compression-molded, and the X-ray fluorescence is measured to measure the NET intensity C of the constituent element of the inorganic fine particles (for example, Si when the inorganic fine particles are silica). Using these values, the free inorganic fine particle ratio can be calculated by the following formula.

(Equation 1)
{(Inorganic fine particle detachment amount (%)) = (NET strength B-NET strength A) / (NET strength B-NET strength C) × 100}

  The inorganic fine particle recovery rate can be calculated by the following formula by measuring the NET strength D of the externally added toner.

(Equation 2)
(Recovery rate of inorganic fine particles (%)) = {(NET strength B) / (NET strength D) × 100}

[Manufacture of toner base particles]
-Preparation of resin fine particle dispersion-
320 parts by mass of styrene (made by Wako Pure Chemical Industries),
80 parts by mass of n-butyl acrylate (Wako Pure Chemical Industries, Ltd.)
β-carboxyethyl acrylate (manufactured by Rhodia Nikka) 9 parts by mass,
1.5 parts by mass of 1′10-decanediol diacrylate (manufactured by Shin-Nakamura Chemical),
2.7 parts by weight of dodecanethiol (Wako Pure Chemical Industries, Ltd.)
The above is mixed and dissolved, dissolved in 550 parts by mass of ion-exchanged water containing 4 parts by mass of the anionic surfactant Dowfax (manufactured by Dow Chemical Co., Ltd.), further dispersed and emulsified in a stirring tank, and slowly stirred for 10 minutes. While stirring and mixing, 50 parts by mass of ion-exchanged water in which 6 parts by mass of ammonium persulfate was dissolved was added.

  Next, after sufficiently replacing the nitrogen in the system, the stirring tank jacket was heated while stirring in the stirring tank until the temperature in the tank reached 70 ° C., and emulsion polymerization was continued for 5 hours. Thus, an anionic resin particle dispersion having a volume average particle size of 210 nm, a solid content of 43%, a glass transition point of 51.0 ° C., and an Mw of 30000 was prepared.

-Preparation of colorant particle dispersion-
90 parts by mass of a phthalocyanine pigment (manufactured by Dainichi Seika Co., Ltd., PVFASTBLUE)
Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen SC) 10 parts by mass,
240 parts by mass of ion exchange water,
The above was mixed in a stirring tank, and this was dispersed using an optimizer HJP-25080 (manufactured by Sugino Machine Co., Ltd.) set at a dispersion pressure of 147 MPa to prepare a colorant particle dispersion. The number average particle size of the colorant in the colorant particle dispersion was 140 nm, particles having a particle size of 0.03 μm or less were 4.0% by number, and particles having a particle size of 0.5 μm or more were 0.4% by number.

-Preparation of release agent particle dispersion-
30 parts by mass of paraffin wax (PolyWax 850, manufactured by Toyo Petrolite)
Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen SC) 2.5 parts by mass,
67.5 parts by mass of ion exchange water,
The above was mixed in a stirring vessel and dispersed using an optimizer HJP-25080 (manufactured by Sugino Machine Co., Ltd.) set to a dispersion pressure of 147 MPa to prepare a release agent particle dispersion. The number average particle size of the release agent in the release agent particle dispersion was 210 nm, the number of particles having a particle size of 0.03 μm or less was 5.0% by number, and the number of particles having a particle size of 0.5 μm or more was 0.4% by number.

-Production of toner particles-
(Aggregation process)
400 parts by mass of ion exchange water,
240 parts by mass of resin particle dispersion,
44 parts by weight of a colorant particle dispersion,
56 parts by mass of release agent particle dispersion,
After the above mixed components are put into a stirring tank and thoroughly mixed and dispersed with a homogenizer,
Flocculant (manufactured by Asada Chemical Co., Ltd., polyaluminum chloride) 0.5 parts by mass,
100 parts by mass of ion exchange water,
The mixed solution was added over 10 minutes while stirring the stirring tank, and after the addition, the mixture was gently heated to 40 ° C. and held for 30 minutes, and then heated to 50 ° C. After maintaining at 50 ° C. for 100 minutes, when the particle size was measured, it was confirmed that 5.5 μm aggregated particles were formed. Further, the temperature of the heating jacket was raised and held at 52 ° C. for 40 minutes. When the particle size (volume average particle diameter, the same applies hereinafter) was measured, it was confirmed that 6.0 μm aggregated particles were produced.

(Adhesion process)
To the dispersion containing the aggregated particles prepared above, 65 parts by mass of the resin particle dispersion was further slowly added, and the temperature of the heating jacket was raised and held at 54 ° C. for 1 hour. The obtained adhered particles were measured to have a particle size of 6.4 μm.

(Fusion process)
Next, a 1 mol / liter sodium hydroxide aqueous solution was added so that the pH was 6.0, and then the mixture was gently heated to 85 ° C. and kept for 60 minutes while stirring was continued. Thereafter, the mixture was heated to 96 ° C., a 1 mol / liter nitric acid aqueous solution was added until the pH reached 5.0, and the mixture was held for 5 hours. Thereafter, the obtained colored resin fine particle slurry was cooled to 42 ° C., and further, this slurry was subjected to sieving treatment with an opening of 25 μm mesh, followed by filtration with a filter press (manufactured by Tokyo Engineering Co., Ltd.). 200 parts by mass of ion-exchanged water (conductivity of 2 μS or less) is passed through the colored resin fine particles in the filter press apparatus with respect to 100 parts by mass of the obtained colorant resin fine particles, and subsequently 1 mol in 300 parts by mass of ion-exchanged water. A colored resin fine particle cake was obtained after passing acid-washed water to which pH / 3.0 of an aqueous nitric acid solution was added until pH 3.0 and passing 500 parts by mass of ion-exchanged water, followed by pressing and dehydration. The colored resin fine particle cake was pulverized and then dried with a dryer (manufactured by a flash jet dryer manufactured by Seishin Corporation) to obtain colored resin fine particles having a particle size of 6.5 μm.

Next, the colored resin fine particles and the external additive were mixed with a Henschel mixer with the following composition to obtain an externally added toner.
Colored resin fine particles 150 parts by weight Silica (volume average particle diameter 40 nm) 2.5 parts by weight Titania (volume average particle diameter 20 nm) 1.8 parts by weight Cerium oxide (volume average particle diameter 150 nm) 1 part by weight

Example 1
The obtained externally added toner was classified using a classifier system shown in FIG. As the cyclone, an all-circular spiral cyclone having the dimensions shown in A in Table 1 was used. At this time, Dc / De = 3 and {H ₁ + H ₂ } /H=1.2. The flow rate adjustment valve was adjusted to process 100 kg at a supply rate of 500 kg / h from the supply machine 1 with an air volume of 20 m ³ / min (normal pressure). The results are shown in Table 2.

(Example 2)
The externally added toner was processed under the same conditions as in Example 1 except that the cyclone size was changed to B in Table 1. At this time, Dc / De = 2 and {H ₁ + H ₂ } /H=1.25.

( Reference Example 3)
The externally added toner was processed under the same conditions as in Example 2 except that the air volume was 15 m ³ / min.

( Reference Example 4)
The externally added toner was processed under the same conditions as in Example 2 except that the air volume was 10 m ³ / min.

(Example 3 )
The externally added toner was processed under the same conditions as in Example 1 except that the cyclone size was changed to C in Table 1. At this time, Dc / De = 2.0 and {H ₁ + H ₂ } /H=1.2.

(Example 4 )
The externally added toner was processed under the same conditions as in Example 1 except that the cyclone size was changed to D in Table 1. At this time, Dc / De = 3.5 and {H ₁ + H ₂ } /H=1.2.

(Example 5 )
The externally added toner was processed under the same conditions as in Example 1 except that the cyclone size was changed to E in Table 1. At this time, Dc / De = 2.5 and {H ₁ + H ₂ } /H=1.15.

(Example 6 )
The externally added toner was processed under the same conditions as in Example 1 except that the cyclone size was changed to F in Table 1. At this time, Dc / De = 2.5 and {H ₁ + H ₂ } /H=1.3.

( Reference Example 1 )
The externally added toner was processed under the same conditions as in Example 1 except that the cyclone size was changed to G in Table 1. At this time, Dc / De = 4.0 and {H ₁ + H ₂ } /H=1.36.

( Reference Example 2 )
The externally added toner was processed under the same conditions as in Example 1 except that the cyclone size was changed to H in Table 1. At this time, Dc / De = 1.7 and {H ₁ + H ₂ } /H=1.09.

(Comparative Example 1)
The toner was manufactured under the same conditions as in Example 1 except that the fine powder separation processing of the external toner was not performed.

(Comparative Example 2)
7 was mixed for 5 minutes at 100 m / s using the Q-type mixer shown in FIG. 7, and the resulting externally added toner was not subjected to fine powder separation.

In the stirring apparatus shown in FIG. 7, a substantially spherical container 51 is accommodated in a cooling pipe 57, a rotating body 52 is provided at the bottom of the container 51, and its rotating shaft 53 is a hollow pipe. N ₂ gas is supplied into 51. The raw material particles are charged into the container 51 through the tube 54 and mixed and stirred by the rotation of the rotating body 52 and the N ₂ gas supplied by the rotating shaft 53. The filter 55 captures the raw material particles conveyed along with the outflow of N ₂ gas and returns them to the container 51. A warp plate 56 is disposed on the inner periphery of the container 51 of the filter 55 so that excessive raw material particles do not enter the filter 55. The volume of the rotating body 52 is ½ or less of the volume in the container 51.

[Evaluation]
Next, each of the above toners was subjected to a sieving treatment with a 45 μm mesh screen, 5 parts of the externally added toner obtained, 1% of polymethyl methacrylate resin (manufactured by Soken Chemical Co., Ltd., weight average molecular weight 75000), ferrite particles (volume average) After mixing 95 parts of a resin-coated carrier using toluene as a solvent with a particle diameter of 50 μm (manufactured by Powdertech) and filling the cartridge, it is used in a high-temperature and high-humidity environment using Docu print C2221 (manufactured by Fuji Xerox). (30 ° C., 80% RH), a printing test of 20,000 sheets was performed, and the image density, fog on paper, and presence / absence of photoconductor filming were visually evaluated. The results are shown in Table 2. ◎ means very good, ○ means good, Δ means gradually worsening, × means bad. The photoconductor filming was evaluated by observing the photoconductor surface after printing 20,000 sheets. The results are shown in Table 2.

  In Table 2, the higher the recovery rate of each external additive indicates that the required amount of the external additive remains in the product toner, and as a result, the performance of each evaluation item is good. It can also be seen that if the liberation rate of Si is too high, the amount of silica present on the surface of the collected product toner particles increases, and as a result, the wax component of the toner particle injection is also exposed and the chargeability deteriorates.

  As shown in these results, by providing a fine powder removing means in the subsequent step of the external addition step, the free external additive can be easily separated, and as a result, the high transfer efficiency and high image quality are maintained, The toner for electrophotography that can stably obtain a high-quality image can be produced by stabilizing the development and transfer processes by the above.

  The present invention is particularly useful for use in electrophotographic toners and developers.

It is the schematic which shows an example of the fine powder removal means of this invention. It is the schematic of an example of the classification apparatus used suitably for this invention. It is a figure explaining the structure of the classification apparatus used suitably for this invention. It is the schematic which shows the other example of the classification apparatus used suitably for this invention. FIG. 4 is a schematic flowchart showing an example of a method for producing a toner of the present invention. It is a flowchart which shows the manufacturing method of the conventional toner. It is the schematic explaining the structure of the conventional Q type mixer.

Explanation of symbols

  1 Supply Machine, 2 Air Inlet, 3 Cyclone, 4 Hopper, 5 Air Knocker, 6 Air Filter, 7 Butterfly Valve, 8 Product Recovery Container, 9 Lifting Device, 10 Bag Filter, 11 Fine Powder Recovery Container, 12 Safety Filter, 13 Pressure Meter, 14 air flow meter, 15 blower, 16 air flow control valve, 17, 36 piping, 18 three-way valve, 20 valve, 32 inlet, floor 40.

Claims (2)

An electrophotographic toner manufacturing apparatus having an external additive toner obtained by adding and mixing an external additive to a toner base particle comprising a binder resin and a colorant;
A resin particle dispersion is mixed with a colorant particle dispersion in which a colorant is dispersed, and the resin particles and the pigment particles are aggregated to form aggregated particles, which are then heated to coalesce the aggregated particles. A stirring tank for
A mixing device for mixing an external additive with the toner base particles composed of the aggregated particles;
A cyclone device having an upper part for discharging fine powder of unattached external additive and a lower part for discharging external additive-attached external toner;
When the air volume is 20 to 45 m ³ / min, the ratio of the diameter Dc of the upper part of the cyclone device and the diameter De of the fine powder outlet of the upper part of the cyclone device is 2.0 ≦ Dc / De ≦ 3.5. An electrophotographic toner manufacturing apparatus, comprising:   2. The removal amount of fine powder finally captured by the cyclone device is 0.01 to 5% by weight with respect to the input amount of pre-toner particles after the external addition step by the mixing device. The electrophotographic toner manufacturing apparatus according to claim.

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