Toner classifier and toner manufacturing method

Abstract

To provide a classifier for toner that indicates a satisfactory yield even when a toner with a small particle diameter is manufactured, and a method for manufacturing toner.SOLUTION: A classifier for toner includes a classifying rotor. A classifying rotor has a plurality of blades that extend from the center of rotation of the classifying rotor toward an outer periphery. The plurality of blades are arranged with a predetermined interval from each other. The interval forms an opening toward a rotation center area of the classifying rotor. The blades are provided to be directed to the upstream side with respect to the direction of rotation of the classifying rotor from a rotation center side end toward an outer peripheral side end of the classifying rotor. The blades each have a bent part. On a cross section when the classifying rotor is cut off in a direction perpendicular to the rotation axis of the classifying rotor, the shape of the blades satisfies a predetermined relational expression. A method for manufacturing toner has a classifying step of performing classifying processing on particles to be classified by using the classifier for toner.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a toner classification device and a method for producing toner used in electrophotography, electrostatic recording, electrostatic printing, and toner jet systems. [Background technology]

[0002] In recent years, full-color electrophotographic copiers have become widespread and are beginning to be applied to the printing market. In the printing market, there is a growing demand for high speed, high image quality, and high productivity while being compatible with a wide range of media (paper types). In the case of toner, a toner with a small particle size and a sharp particle size distribution stabilizes the charging properties, which stabilizes the developability and transferability, thereby achieving high image quality. A melt-kneading pulverization method is known as one of the common methods for producing toner. A specific example of a method for producing toner particles using the melt-kneading pulverization method is as follows. Toner raw materials such as binder resin, colorant, and release agent are melted and kneaded, cooled and solidified, and then the kneaded mixture is pulverized by a pulverizing means to obtain toner particles. Thereafter, if necessary, the toner is produced by classifying the particles to a desired particle size distribution, adjusting the circularity by making the toner particles spherical through heat treatment, or adding a fluidizing agent such as inorganic fine particles.

[0003] Various types of crushing devices are used as a means for crushing kneaded materials. One known example of such a mechanical crushing device (Patent Document 1) is one that includes a rotor supported by a central rotating shaft and having multiple convex and concave portions on its outer peripheral surface within a casing having an inlet and outlet for the material to be crushed, and a stator arranged on the outside of the rotor with a predetermined gap from the rotor's outer peripheral surface and having multiple convex and concave portions on its inner peripheral surface.As the material to be crushed passes through a processing section where the rotor and stator oppose each other, carried by the airflow flowing from the inlet to the outlet, it crushes the material to be crushed by colliding with the convex or concave portions of the rotor or stator. Furthermore, fine powders generated during the grinding process are mixed into the pulverized material that has been ground to a desired particle size by a grinding device. If these fine powders are present in the toner, they can cause problems in the electrophotographic process, such as fogging, and are therefore generally removed by classification. Known methods for producing toner that involve classification using a classifier include a method for producing toner that uses an airflow type classifier that utilizes the Coanda effect (Patent Document 2) and a method for producing toner that uses a centrifugal wind classifier (Patent Document 3).

[0004] When using a centrifugal air classifier, the pulverized mixture of the toner raw material, which is the particles to be classified, is transported from the inlet to the vicinity of the outer periphery of the classification rotor by the airflow from the outer periphery of the classification rotor to the inside, and centrifugal force is applied to the particles at the outer periphery of the classification rotor by the rotation of the classification rotor. Since the centrifugal force acting on the particles to be classified is a force toward the outside of the classification rotor and is proportional to the weight of the particles, the centrifugal force acting on the fine powder in the particles to be classified is smaller than the drag given by the airflow from the outer periphery of the classification rotor to the inside. Therefore, the fine powder passes between the blades of the classification rotor and is collected by a fine powder collecting means connected to the inside of the classification rotor, and the classified material from which the fine powder has been removed is collected by a classified material collecting means arranged on the outside of the classification rotor, and is classified. Also proposed is a method for producing toner that uses a classification means having multiple blades arranged at regular intervals on the same circumference, with each blade being arranged to form an angle θ of 20° to 65° with respect to a straight line connecting the center of the classification rotor and the tip of the blade (Patent Document 4). In the classification means used in this production method, air that enters between the blades from the outside of the classification rotor rotating at high speed is separated into a component that moves toward the center of rotation and a component that is expelled to the outside of the classification rotor, generating a vortex. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-237816 A [Patent Document 2] JP 2001-201890 A [Patent Document 3] JP 2008-26457 A [Patent Document 4] JP 2010-160374 A Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, the classification process is carried out by adjusting the balance between the drag and centrifugal forces acting on the particles to be classified. However, due to factors such as turbulence in the airflow inside the classifier, aggregation of the particles to be classified, variation in the speed at which the particles to be classified approach the classifying rotor, and vortexes occurring between the blades of the classifying rotor, particles that should not be taken in as fine powder may be mistakenly sucked in and removed. The closer the average particle size of the particles to be classified is to the particle size of the fine powder that should be removed by the classification process, the greater the proportion of particles removed by mistaken suction. Therefore, it has been confirmed that the yield of the classification process decreases when the particle size of the toner is reduced. In addition, it is believed that the vortex generated in the toner manufacturing method described in Patent Document 4 is generated in a shape that follows the blade. It was confirmed that when the angle θ exists, the vortex is generated outside the classification rotor rather than in the classification rotor arranged on the above-mentioned radial straight line, so the rate of erroneous absorption of the classified particles is reduced and the yield is improved. However, it was also confirmed that when the angle θ is too large, the gap between the inner blades of the classification rotor becomes too narrow, making it difficult for fine powder to pass through, and sufficient fine powder removal is not possible.

[0007] As mentioned above, toner particle size reduction is required to improve image quality. The particle size of the pulverized material obtained by the pulverization process after melting and kneading the mixture of toner raw materials is dominant over the particle size of the final toner. Therefore, the pulverized material must be made small in order to reduce the particle size of the toner. The classification process is a process for removing fine powder that can be a problem factor in the electrophotographic process. However, when the toner particle size is reduced, the average particle size of the pulverized material and the particle size of the fine powder that should be removed by the classification process become close to each other. Therefore, there is a problem that some particles that should not be removed because they have an appropriate particle size for toner are removed as fine powder, resulting in a decrease in yield. The present disclosure has an object to solve the above problems and provide a toner classification device and a toner manufacturing method that show a good yield even when a toner having a small particle size is manufactured. [Means for solving the problem]

[0008] The present disclosure relates to A toner classifying device having a classification rotor, The classification rotor has a plurality of blades extending from a rotation center side to an outer periphery side of the classification rotor, The plurality of blades are arranged at predetermined intervals from one another, The interval forms an opening toward a rotation center region of the classifying rotor, the blades are provided so as to be located upstream in the rotation direction of the classifying rotor from the end of the classifying rotor on the rotation center side toward the end of the classifying rotor on the outer periphery side, The blade has a bent portion, In a cross section of the classification rotor cut in a direction perpendicular to the rotation axis of the classification rotor, (i) an angle θ1 formed by a line connecting the rotation center of the classifying rotor and the end of the blade on the rotation center side and a line connecting the end of the blade on the rotation center side and the bent portion of the blade is 30° to 65°; (ii) The distance from the rotation center of the classification rotor to the outer peripheral end of the blade is L1, the distance from the rotation center of the classification rotor to the rotation center side end of the blade is L2, When the distance from the rotation center to the bent portion of the blade is L3, the following formula is satisfied: 0.65≦(L3-L2) / (L1-L2)≦0.85 (iii) an angle θ2 formed by a line connecting the rotation center side end of the blade and the bent portion of the blade and a line connecting the bent portion of the blade and the outer periphery side end of the blade is 5° to 25°; (iv) The present invention relates to a toner classification device, wherein the sum of θ1 and θ2 is 55° to 85°.

[0009] The present disclosure also provides A toner manufacturing method including a classification step of classifying particles to be classified using a toner classifier, The toner classification device comprises: A toner classifying device having a classification rotor, The classification rotor has a plurality of blades extending from a rotation center side to an outer periphery side of the classification rotor, The plurality of blades are arranged at predetermined intervals from one another, The interval forms an opening toward a rotation center region of the classifying rotor, the blades are provided so as to be located upstream in the rotation direction of the classifying rotor from the end of the classifying rotor on the rotation center side toward the end of the classifying rotor on the outer periphery side, The blade has a bent portion, In a cross section of the classification rotor cut in a direction perpendicular to the rotation axis of the classification rotor, (i) an angle θ1 formed by a line connecting the rotation center of the classifying rotor and the end of the blade on the rotation center side and a line connecting the end of the blade on the rotation center side and the bent portion of the blade is 30° to 65°; (ii) when the distance from the rotation center of the classifying rotor to the outer circumferential end of the blade is L1, the distance from the rotation center of the classifying rotor to the rotation center side end of the blade is L2, and the distance from the rotation center of the classifying rotor to the bent portion of the blade is L3, the following formula is satisfied, 0.65≦(L3-L2) / (L1-L2)≦0.85 (iii) an angle θ2 formed by a line connecting the rotation center side end of the blade and the bent portion of the blade and a line connecting the bent portion of the blade and the outer periphery side end of the blade is 5° to 25°; (iv) the sum of θ1 and θ2 is 55° to 85° The present invention relates to a method for producing a toner, Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a toner classification device and a toner manufacturing method that exhibit good yield even when producing toner with a small particle size. [Brief description of the drawings]

[0011] [Figure 1] Schematic diagram of the classification rotor [Diagram 2] Diagram of air flow between the blades [Diagram 3] Schematic diagram of a toner classification device used in the examples [Figure 4] Schematic diagram of the dispersion rotor used in the examples [Diagram 5] Schematic diagram of a guide means used in the embodiment [Figure 6] Schematic diagram of the liner used in the examples DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In the present disclosure, the expressions "XX or more and YY or less" and "XX to YY" representing a numerical range mean a numerical range including the endpoints, that is, the lower limit and the upper limit, unless otherwise specified.

[0013] FIG. 1 shows a schematic diagram of a classification rotor provided in a toner classification device. has a plurality of blades 11 extending from the rotation center side to the outer periphery side of the classifying rotor 31. The plurality of blades 11 are arranged at a predetermined interval from each other. The interval forms an opening toward the rotation center region of the classifying rotor 31. The blades 11 are provided so as to be on the upstream side with respect to the rotation direction of the classifying rotor 31 as they move from the end on the rotation center side to the end on the outer periphery side of the classifying rotor 31. The blades 11 have a bent portion. In addition, in a cross section of the classifying rotor 31 cut in a direction perpendicular to the rotation axis of the classifying rotor 31, (i) the angle θ1 between a line connecting the rotation center of the classifying rotor 31 and the end of the blade 11 on the rotation center side and a line connecting the end of the blade 11 on the rotation center side and the bent portion of the blade is 30° to 65°; (ii) When the distance from the rotation center of the classifying rotor 31 to the outer circumferential end of the blade 11 is L1, the distance from the rotation center of the classifying rotor 31 to the rotation center side end of the blade 11 is L2, and the distance from the rotation center of the classifying rotor 31 to the bent portion of the blade 11 is L3, the following formula is satisfied: 0.65≦(L3-L2) / (L1-L2)≦0.85 (iii) an angle θ2 formed by a line connecting the rotation center side end of the blade 11 and the bent portion of the blade 11 and a line connecting the bent portion of the blade 11 and the outer periphery side end of the blade 11 is 5° to 25°, (iv) The sum of θ1 and θ2 is 55° to 85°. In Fig. 1, reference numeral 12 denotes an upper part of the classifying rotor frame, and reference numeral 13 denotes a lower part of the classifying rotor frame. Furthermore, the portion of the blade 11 from the end on the rotation center side to the bent portion may be straight or curved, but is preferably straight as shown in Fig. 1. Furthermore, the portion of the blade 11 from the bent portion to the end on the outer periphery side may be straight or curved, but is preferably straight as shown in Fig. 1.

[0014] When the above-mentioned classifying rotor is used, it is possible to provide a toner classifying device that can sufficiently remove fine particles even when the toner has a small particle size, and can exhibit a good yield. The present inventors assume that the reason for this is as follows. The centrifugal force acting on an object is expressed as [weight of object] x [radius of rotation] x [square of angular velocity of rotational motion]. Here, the radius of rotation of the classified particle is considered to be the distance between the center of rotation of the classification rotor and the classified particle. As mentioned above, it is assumed that vortices are generated between the blades of the classification rotor rotating at high speed when performing classification processing. The presence of these vortices generates localized air currents that strongly draw particles inward, which is assumed to draw in and remove particles that should not be removed. If the vortex exists inside the classification rotor, the classified particle is drawn in toward the inside of the classification rotor, and the distance from the center of rotation becomes smaller, which reduces the centrifugal force, making it impossible for the particle to return to the outside of the classification rotor, and as a result, it is removed as fine powder. The classification rotor is arranged so that, in a cross section of the classification rotor cut in a direction perpendicular to the rotation axis of the classification rotor, a straight line connecting the rotation center of the classification rotor and the end of the blade on the rotation center side and a straight line connecting the end of the blade on the rotation center side and the bent part of the blade form an angle θ1. In addition, the blade itself has a bent part, and a straight line connecting the end of the blade on the rotation center side and the bent part of the blade and a straight line connecting the bent part of the blade and the outer periphery side end of the blade form an angle θ2, so that the position of the vortex generated during classification can be made on the outside, and even if particles that should not be removed are drawn in by the vortex, the centrifugal force does not become small and the particles can return to the outside of the classification rotor, which is thought to improve the yield.

[0015] θ1 must be 30 to 65°. If θ1 is less than 30°, the effect of shifting the position where the vortex is generated to the outside is insufficient. If θ1 exceeds 65°, the distance near the inner ends of the blades of the classification rotor becomes too close, making it difficult for fine powder to be removed from the particles to be classified to pass through. θ1 is preferably 35° to 65°, and more preferably is 45°~65°. Moreover, θ2 must be between 5° and 25°. If θ2 is less than 5°, the effect of shifting the position where the above-mentioned vortex occurs to the outside is insufficient. If θ2 exceeds 25°, the angle of the blade itself is too steep, and a second vortex of the airflow occurs near the bend as shown in Fig. 2(b), which further draws particles inward. θ2 is preferably between 10° and 25°, and more preferably between 15° and 20°. Furthermore, from the viewpoint of positioning the above-mentioned vortex generation position sufficiently outside, the sum of θ1 and θ2 (θ1+θ2) needs to be 55° to 85°, preferably 65° to 85°, and more preferably 75° to 85°.

[0016] Furthermore, when the distance from the center of rotation of the classifying rotor to the outer peripheral end of the blade is L1, the distance from the center of rotation of the classifying rotor to the end of the blade on the rotation center side is L2, and the distance from the center of rotation of the classifying rotor to the bent portion of the blade is L3, it is necessary to satisfy 0.65≦(L3-L2) / (L1-L2)≦0.85. If (L3-L2) / (L1-L2) is greater than 0.85, the bent portion is too close to the outer periphery of the classifying rotor, and the effect of providing θ2 is not realized. Also, if (L3-L2) / (L1-L2) is less than 0.65, the length of the blade from the outer periphery end to the bent portion becomes longer, generating a second airflow vortex as shown in Figure 2(c), which draws particles that should not be removed further toward the center of rotation of the classifying rotor.

[0017] The radius of the classification rotor is not particularly limited and can be set appropriately depending on the dimensions of the classification device and the amount of particles to be treated, and can be, for example, 60 mm to 120 mm. The height of the blades of the classification rotor is not particularly limited and can be set appropriately depending on the dimensions of the classification rotor and classification device and the amount of particles to be treated, and can be, for example, 50 mm to 100 mm. The number of blades of the classification rotor is not particularly limited, and can be appropriately set according to the dimensions of the classification rotor and the classification device, the amount of particles to be treated, and the like. For example, it can be 20 to 60 blades. Furthermore, the spacing between the blades arranged on the classification rotor at their outer circumferential ends is not particularly limited, and can be set appropriately depending on the dimensions of the classification rotor and classification device, the amount of particles to be treated, and the like. For example, from the viewpoint of preventing the airflow vortex generated between the blades arranged on the classification rotor from becoming too large, the distance between the blades arranged on the classification rotor at the outer peripheral end is preferably 25 mm or less, and from the viewpoint of preventing the time required for processing from becoming longer due to the narrowing of the opening, it is preferable to set the distance to 5 mm or more.

[0018] The toner classifier is not particularly limited as long as it has the classification rotor for removing fine powder from the particles to be classified, and may, for example, have a supply means for supplying the particles to be classified and a recovery means for the classified material after classification in the main body of the toner classifier. As the particle size of the particles to be classified becomes smaller, the number of particles per unit weight increases, and therefore the number of contact points between particles increases, making it easier for aggregates to form. From the viewpoint of being able to proceed with the classification process while breaking up these aggregates, the toner classifier has a configuration as shown in FIG. A cylindrical main body casing; The classifying rotor 31, A cylindrical guide means 36 is installed in a state in which at least a part of the classifying rotor is covered; a particle inlet 34 to be classified and a particle supply means 35 having the particle inlet 34 to be classified, the particle inlet 34 being formed on a side surface of the main casing for introducing the particles to be classified; A fine powder discharge port 39 and a classified particle extraction port 37 are formed on a side surface of the main casing in order to discharge the classified particles from which fine powder has been removed outside the main casing; A dispersion rotor 32 is disposed in the main casing and is attached to a central rotating shaft. The dispersion rotor 32 has a dispersion hammer (e.g., a square block) 33 on a side surface of the rotor on the side of the classifying rotor 31. The main casing and the guide means 36 are not limited to a cylindrical shape and may be of any shape. It is believed that the presence of the guiding means 36 generates an ascending air current toward the classifying rotor 31 in the first space A, and a descending air current toward the dispersing rotor 32 in the second space B, making it possible to carry out the classification process while breaking down agglomerates of the particles to be classified by the dispersing hammer 33. The dispersing hammer 33 is not limited to a square block and can be of any shape as long as it can break down agglomerates of the particles to be classified. Furthermore, from the viewpoint of improving the flowability by increasing the average circularity of the toner, it is more preferable to have a liner 38 fixedly disposed at a distance from the periphery of the dispersion rotor 32. It is preferable that the liner 38 has a groove on the surface facing the dispersion rotor 32. It is believed that when the particles to be classified collide with the rotating dispersion hammer or the surface of the liner facing the dispersion hammer, the convex parts of the particles to be classified are crushed, resulting in an increase in circularity. If the fine powder removal efficiency during classification is low, the number of particles to be classified present in the casing remains large compared to when the fine powder removal efficiency is high, and this may reduce the effect of improving the circularity of the particles.

[0019] The toner classifier can be applied to powder particles obtained by known manufacturing methods such as the melt kneading pulverization method, the suspension polymerization method, the emulsion aggregation method, and the dissolution suspension method, but is particularly suitable for use in the melt kneading pulverization method, since fine powder is likely to be generated when the toner is made into a small particle size. The procedure for manufacturing a toner by the melt kneading pulverization method will be described below, but is not limited to the following procedure.

[0020] <Method of manufacturing toner particles> First, in the raw material mixing process, at least a predetermined amount of binder resin is weighed and mixed as a toner raw material. If necessary, a colorant, a release agent that suppresses the occurrence of hot offset during heat fixing of the toner, a dispersant that disperses the release agent, a charge control agent, etc. may be mixed. Examples of mixing devices include a double con mixer, a V-type mixer, a drum type mixer, a super mixer, a Henschel mixer, and a Nauta mixer.

[0021] Furthermore, in the melt-kneading step, the toner raw materials blended and mixed in the raw material mixing step are melt-kneaded to melt the resins and disperse the colorant therein. In the melt-kneading step, for example, a batch type kneader such as a pressure kneader or a Banbury mixer, or a continuous type kneader can be used. In recent years, single-screw or twin-screw extruders have become mainstream due to their advantages such as continuous production, and for example, a KTK type twin-screw extruder manufactured by Kobe Steel, Ltd., a TEM type twin-screw extruder manufactured by Toshiba Machine Co., Ltd., a twin-screw extruder manufactured by KCK Corporation, and a co-kneader manufactured by Buss Co., Ltd. are commonly used. Furthermore, the molten and kneaded product obtained by melting and kneading the toner raw materials is rolled with two rolls or the like after melting and kneading, and is cooled through a cooling step in which it is cooled with water or the like.

[0022] The cooled molten mixture obtained in the cooling step is then pulverized to a desired particle size in a pulverization step. In the pulverization step, the mixture is first coarsely pulverized using a crusher, hammer mill, feather mill, or the like. The mixture is then finely pulverized using a mechanical pulverizer such as an Innomizer (manufactured by Hosokawa Micron Corporation), a Cryptron (manufactured by Kawasaki Heavy Industries, Ltd.), a Super Rotor (manufactured by Nisshin Engineering Co., Ltd.), or a Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.) to obtain a pulverized product. In this manner, the mixture is pulverized stepwise to a predetermined toner particle size in the pulverization step.

[0023] The pulverized product obtained in the pulverization step is treated as particles to be classified, and a toner classifier is used to classify the particles to be classified (classification step), thereby obtaining toner particles. The obtained toner particles may be used as they are, but in order to impart functionality required of the toner, inorganic fine particles such as silica may be added to the toner particles as necessary, and then the toner may be subjected to a thermal sphering treatment or the like to produce a toner.

[0024] In order to improve the transferability of the toner, the average circularity of the toner is preferably 0.955 or more, more preferably 0.960 or more, and from the viewpoint of suppressing cleaning defects, the average circularity is preferably 0.990 or less. In addition, the weight average particle diameter of the toner is preferably small from the viewpoint of improving the quality of the image formed by the toner, specifically, it is preferably 3.50 μm to 6.00 μm, and more preferably 3.50 μm to 5.00 μm. Although it is preferable that the weight average particle diameter of the toner is small, if it is 3.50 μm or more, it is unlikely to slip through the cleaning blade and become a cause of image defects. Furthermore, the percentage by number of toner particles having a size of 3.0 μm or less is preferably 20.0% by number or less, more preferably 15.0% by number or less, and even more preferably 10.0% by number or less.

[0025] <Toner raw materials> Next, the raw materials of the toner containing at least the binder resin will be described.

[0026] <Binding resin> As the binder resin, a general resin can be used, and examples thereof include polyester resin, styrene-acrylic acid copolymer, polyolefin resin, vinyl resin, fluororesin, phenol resin, silicone resin, and epoxy resin. Among these, from the viewpoint of improving low-temperature fixing property, amorphous polyester resin is preferred. From the viewpoint of achieving both low-temperature fixing property and hot offset resistance, low-molecular-weight polyester resin and high-molecular-weight polyester resin may be used in combination. From the viewpoint of further improving the low-temperature fixing property and blocking resistance during storage, a crystalline polyester resin can also be used as a plasticizer.

[0027] <Coloring agent> The toner raw materials may contain a colorant. Examples of the colorant that may be contained in the toner raw materials include the following. The colorant may be a known organic pigment or oil-based dye, carbon black, or a magnetic material. Examples of cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and basic dye lake compounds. Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Examples of black colorants include carbon black, magnetic materials, and those toned to black using the above-mentioned yellow colorants, magenta colorants, and cyan colorants. The colorants may be used alone or in combination of two or more.

[0028] <Release agent> If necessary, a release agent may be used to suppress the occurrence of hot offset during the heat fixing of the toner. Examples of the release agent include low molecular weight polyolefins, silicone wax, fatty acid amides, ester waxes, carnauba wax, and hydrocarbon waxes. Can be exemplified

[0029] The methods for measuring various physical properties of the toner and raw materials are described below. <Method of measuring weight average particle size (D4) of toner> The weight-average particle size (D4) of the toner was measured using a precision particle size distribution measuring device called the Coulter Counter Multisizer, which is equipped with a 100 μm aperture tube and uses the narrow hole electrical resistance method. Using a Beckman Coulter Multisizer 3 (registered trademark, manufactured by Beckman Coulter) and the accompanying dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter) for setting measurement conditions and analyzing measurement data, measurements are taken with an effective number of measurement channels of 25,000, and the measurement data is analyzed and calculated. The electrolyte solution used for the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of approximately 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter). Before carrying out the measurements and analyses, the dedicated software is set up as follows. In the "Change Standard Measurement Method (SOM) screen" of the dedicated software, set the total count number in the control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particle 10.0 μm" (Beckman Coulter). Press the threshold / noise level measurement button to automatically set the threshold and noise level. In addition, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check the aperture tube flush after measurement. In the "Pulse to particle size conversion setting screen" of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 2 μm to 60 μm.

[0030] The specific measurement method is as follows. (1) Pour about 200 ml of the electrolyte solution into a 250 ml round-bottom glass beaker made exclusively for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "aperture tube flush" function of the analysis software to remove dirt and air bubbles from inside the aperture tube. (2) Approximately 30 ml of the above-mentioned aqueous electrolyte solution is placed in a 100 ml flat-bottom glass beaker, and approximately 0.3 ml of a solution prepared by diluting "Contaminon N" (a 10% by weight aqueous solution of a neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, with a pH of 7, manufactured by Wako Pure Chemical Industries, Ltd.) three times by weight with ion-exchanged water is added as a dispersant. (3) A predetermined amount of ion-exchanged water is placed in the water tank of an ultrasonic disperser "Ultrasonic Dispersion System Tetora150" (manufactured by Nikkaki Bios Co., Ltd.) that has two oscillators with an oscillation frequency of 50 kHz built in with a phase shift of 180 degrees and an electrical output of 120 W, and approximately 2 ml of the Conaminon N is added to this water tank. (4) The beaker (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid surface of the electrolyte solution in the beaker is maximized. (5) While the electrolyte solution in the beaker in (4) is irradiated with ultrasonic waves, about 10 mg of toner is added little by little to the electrolyte solution and dispersed. Then, ultrasonic dispersion treatment is continued for another 60 seconds. During ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be 10°C or higher and 40°C or lower. (6) Using a pipette, add the electrolyte solution (5) in which the toner is dispersed to the round-bottom beaker (1) placed in the sample stand, and adjust the measurement concentration to about 5%. Then, measurements are continued until the number of particles measured reaches 50,000. (7) The measurement data is analyzed using the dedicated software that comes with the device, and the weight-average particle size (D4) is calculated. Note that when the dedicated software is set to Graph / Volume%, the "Average diameter" on the Analysis / Volume Statistics (Arithmetic Mean) screen is the weight-average particle size (D4).

[0031] <Measuring method for the percentage of toner particles 3.0 μm or smaller> In step (7) of the measurement method for the weight-average particle diameter (D4) of toner, when the dedicated software is set to Graph / Number %, the cumulative number % in the particle diameter range of 3.0 μm or less is the number % of particles less than 3.0 μm.

[0032] <Method for measuring average circularity> The average circularity of the toner is measured using a flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under the measurement and analysis conditions during the calibration process. The specific measurement method is as follows. First, about 20 ml of ion-exchanged water from which impurities such as solids have been removed is placed in a glass container. About 0.2 ml of a dilution solution obtained by diluting "Contaminon N" (a 10% aqueous solution of a neutral detergent for cleaning precision measuring instruments with a pH of 7, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) with ion-exchanged water by about 3 times by mass as a dispersant is added to the container. About 0.02 g of the measurement sample is further added, and the dispersion treatment is performed for 2 minutes using an ultrasonic disperser to obtain a dispersion liquid for measurement. At that time, the dispersion liquid is appropriately cooled so that the temperature is 10°C or higher and 40°C or lower. As the ultrasonic disperser, a tabletop ultrasonic cleaner disperser ("VS-150" (manufactured by Vervoclear Co., Ltd.) with an oscillation frequency of 50 kHz and an electrical output of 150 W is used, a predetermined amount of ion-exchanged water is placed in the water tank, and about 2 ml of the Contaminon N is added to the water tank. For the measurement, the flow type particle image analyzer equipped with a standard objective lens (10x) was used, and the particle sheath "PSE-900A" (manufactured by Sysmex Corporation) was used as the sheath liquid. The dispersion liquid prepared according to the above procedure was introduced into the flow type particle image analyzer, and 3000 toner particles were measured in HPF measurement mode and total count mode. The binarization threshold during particle analysis was set to 85%, and the analyzed particle diameter was limited to a circle equivalent diameter of 1.985 μm or more and less than 39.69 μm, and the average circularity of the toner particles was obtained. Before starting the measurement, automatic focus adjustment is performed using standard latex particles (Duke Scientific's "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A" diluted with ion-exchanged water). After that, it is preferable to perform focus adjustment every 2 hours from the start of the measurement. In the examples of the present application, a flow-type particle image analyzer was used that had been calibrated by Sysmex Corp. and had a calibration certificate issued by Sysmex Corp. Measurements were performed under the same measurement and analysis conditions as when the calibration certificate was received, except that the particle diameters analyzed were limited to a circle-equivalent diameter of 1.985 μm or more and less than 39.69 μm. EXAMPLES

[0033] Hereinafter, the present disclosure will be described in more detail using examples and comparative examples, but the aspects of the present disclosure are not limited thereto. Hereinafter, the number of parts in the examples and comparative examples is based on parts by mass unless otherwise specified.

[0034] <Examples of binder resin production> Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane: 72.0 parts (100 mol% based on the total number of moles of polyhydric alcohol) Terephthalic acid: 28.0 parts (96 mol% based on the total number of moles of polycarboxylic acids) Tin 2-ethylhexanoate (esterification catalyst): 0.5 parts The above materials were weighed and placed in a reaction vessel equipped with a cooling tube, a stirrer, a nitrogen inlet tube, and a thermocouple. Next, the atmosphere in the flask was replaced with nitrogen gas, and the temperature was gradually raised with stirring, and the reaction was carried out for 8 hours at a temperature of 220°C with stirring. The pressure inside the reaction vessel was then reduced to 8.3 kPa and maintained for 1 hour, after which the vessel was cooled to 180° C. and returned to atmospheric pressure. Trimellitic anhydride: 1.3 parts (4 mol% based on the total number of moles of polycarboxylic acids) tert-Butylcatechol (polymerization inhibitor): 0.1 parts The above materials were then added, the pressure in the reaction vessel was lowered to 8.3 kPa, and the reaction was carried out for 1 hour while maintaining the temperature at 180° C., to obtain a binder resin (amorphous polyester resin). The softening point of the obtained binder resin, measured according to ASTM D36-86, was 110° C.

[0035] <Production example of ground particles for toner (particles to be classified)> Binding resin 90 parts Fischer-Tropsch wax (hydrocarbon wax, melting point 90°C) 5 parts CI Pigment Blue 15:3 5 parts The above materials were mixed in a Henschel mixer (FM-75, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 20 s. -1 After mixing for 5 minutes at 100°C, the mixture was kneaded in a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation). The barrel temperature during kneading was set so that the outlet temperature of the kneaded product was 120°C. The outlet temperature of the kneaded product was directly measured using a handy type thermometer HA-200E manufactured by Anritsu Keiki Co., Ltd. The kneaded product obtained was cooled and coarsely crushed in a pin mill to a volume average particle size of 100 μm or less to obtain a coarsely crushed product. The coarsely crushed material was pulverized using a mechanical pulverizer (Turbo Mill T250-CRS, rotor shape RS type, manufactured by Turbo Kogyo Co., Ltd.) at a rotor rotation speed of 12000 rpm and a pulverization feed of 10 kg / h to obtain a finely crushed material. The finely crushed material was further pulverized at a rotor rotation speed of 12000 rpm and a pulverization feed of 10 kg / h to obtain pulverized particles for toner (classified particles). The classified particles had a weight-average particle size of 4.40 μm, a number percentage of particles below 3.0 μm of 42.5%, and an average circularity of 0.952.

[0036] <Toner classifier> The toner classifier shown in FIG. 3 was used as the toner classifier. A cylindrical main body casing; The main casing includes a rotating body attached to a central rotating shaft, a disk-shaped dispersion rotor 32 having a plurality of dispersion hammers 33 on a side surface of the rotor facing the classifying rotor and rotating at high speed; a liner 38 disposed around the dispersion rotor 32 at a distance therefrom; A classification rotor 31 which is a means for classifying the particles to be classified; a fine powder discharge port 39 for discharging and removing fine powder having a predetermined particle size or less selected by the classifying rotor 31; A cold air inlet (not shown) for introducing cold air from the bottom of the dispersion rotor; a particle inlet 34 for introducing the particles to be classified into the inside of the main casing and a particle supply means 35 having the particle inlet 34; a classified particle extraction port 37 for discharging the classified particles after classification; A cylindrical guide means 36 is installed in a state in which at least a part of the classifying rotor 31 is covered. It is composed of: The guiding means 36 divides the space of the main casing within the toner classifier into space A where an airflow is generated in a direction to introduce the particles to be treated into the classifying rotor 31, and space B where an airflow is generated in a direction to introduce the particles to be treated between the dispersion rotor 32 and the liner 38.

[0037] The height of the space in the main casing was 300 mm, and the inner diameter was 300 mm. The outer diameter of the dispersion rotor was 285 mm, and eight dispersion hammers were attached to the dispersion rotor as shown in Figure 4. The length, width, and height of the dispersion hammers were 30 mm, 20 mm, and 20 mm, respectively. As shown in FIG. 5, the cylindrical guide means is connected to a guide means support member 51. The inner means support member and the main casing can be connected with screws, etc. The guide means has a diameter of 250 mm, a height of 230 mm, and a distance between the top of the guide means and the top of the casing of 20 mm.

[0038] <Classification rotor 1> The classification rotor 1 used in the experiment had the shape shown in Figure 1, with θ1 being 35°, θ2 being 23°, L1 being 82mm, L2 being 57mm, L3 being 76mm, and the height of the opening of the classification rotor being 88mm. The number of blades was 30.

[0039] <Practical classification rotors 2-8, comparative classification rotors 1-10> The differences between the practical classification rotors 2 to 8 and the comparative classification rotors 1 to 10 and the practical classification rotor 1 are summarized in Table 1.

[0040] [Table 1]

[0041] <liner> Liner 1 had multiple convex portions and concave portions formed between the convex portions as shown in Fig. 6, the shape of the concave portions was triangular, the repeat distance between the convex portions was 3 mm, the depth of the concave portions was 3.0 mm, and the height of the liner was 50 mm. Liner 2 was a liner 1 with the concave and convex surfaces removed and the surface smoothed.

[0042] <Toner manufacturing method example 1> The toner classification device is equipped with the classification rotor 1 and liner 2, the rotation speed of the classification rotor is 9000 rpm, the rotation speed of the dispersion rotor is 5000 rpm, and the blower air volume is 10 m 3 Toner 1 was obtained by performing 60 cycles of classification using ground particles for toner as the particles to be classified under the conditions of a classification cycle of 60 sec (10 sec for feeding particles to be classified, 30 sec for classification processing, and 20 sec for collecting the classified particles after processing) and a weight of 200 g of particles to be classified per cycle. In addition, by changing the conditions shown in Table 2, toners 2 to 9 and comparative toners 1 to 10 were obtained.

[0043] [Table 2]

[0044] <Example 1> The weight average particle diameter D4, the percentage of particles 3.0 μm or less, and the average circularity were evaluated by measuring the particle size distribution of Toner 1. The classification yield was calculated from the input amount of the classified particles (200 g x 60 cycles) and the weight of the obtained Toner 1.

[0045] <Yield evaluation criteria> A: Yield 70% or more B: Yield: 60% or more, less than 70% C: Yield: 50% or more, less than 60% D: Yield less than 50%

[0046] <Evaluation criteria for percentage of particles 3.0μm or less> A: 10.0% or less B: More than 10.0% by number, 15.0% by number or less C: More than 15.0% by number and less than 20.0% by number D: 20.0% or more

[0047] <Evaluation criteria for average circularity> A: Average circularity 0.960 or more B: Average circularity 0.955 or more and less than 0.960 C: Average circularity less than 0.955

[0048] <Examples 2 to 9 and Comparative Examples 1 to 10> The evaluation was carried out in the same manner as in Example 1, except that the toner was changed as shown in Table 3. The evaluation results are shown in Table 3.

[0049] [Table 3] [Explanation of symbols]

[0050] 11. Blade, 12. Upper part of classifying rotor frame, 13. Lower part of classifying rotor frame, 31. Classifying rotor, 32. Dispersing rotor, 33. Dispersing hammer, 34. Inlet for particles to be classified, 35. Means for supplying particles to be classified, 36. Guide means, 37. Inlet for extracting classified material, 38. Liner, 39. Fine powder outlet, 51. Support member for guide means

Claims

1. A toner classifying device having a classification rotor, The classification rotor has a plurality of blades extending from a rotation center side to an outer periphery side of the classification rotor, The plurality of blades are arranged at predetermined intervals from one another, The interval forms an opening toward a rotation center region of the classifying rotor, the blades are provided so as to be located upstream in the rotation direction of the classifying rotor from the end of the classifying rotor on the rotation center side toward the end of the classifying rotor on the outer periphery side, The blade has a bent portion, In a cross section of the classification rotor cut in a direction perpendicular to the rotation axis of the classification rotor, (i) an angle θ1 formed by a straight line connecting the rotation center of the classification rotor and the end of the blade on the rotation center side and a straight line connecting the end of the blade on the rotation center side and the bent portion of the blade is 30° to 65°; (ii) when the distance from the rotation center of the classifying rotor to the outer circumferential end of the blade is L1, the distance from the rotation center of the classifying rotor to the rotation center side end of the blade is L2, and the distance from the rotation center of the classifying rotor to the bent portion of the blade is L3, the following formula is satisfied: 0.65≦(L3-L2) / (L1-L2)≦0.85 (iii) an angle θ2 formed by a line connecting the rotation center side end of the blade and the bent portion of the blade and a line connecting the bent portion of the blade and the outer periphery side end of the blade is 5° to 25°; (iv) the sum of θ1 and θ2 is 55° to 85° A toner classifying device comprising:

2. 2. The toner classification device according to claim 1, wherein the sum of θ1 and θ2 is 65° to 85°.

3. A main body casing; A guide means is installed in a state in which at least a part of the classifying rotor is covered; a particle inlet formed on a side surface of the main casing for introducing particles to be classified and a particle supplying means having the particle inlet; a fine powder discharge port and a classified particle extraction port formed on a side surface of the main casing for discharging the classified particles from which fine powder has been removed outside the main casing; a dispersion rotor, which is a rotor attached to a central rotating shaft within the main casing and has a dispersion hammer on a side surface of the rotor facing the classifying rotor; The toner classifying device according to claim 1 or 2, further comprising:

4. 4. The toner classifying device according to claim 3, further comprising a liner fixedly disposed around the periphery of the dispersion rotor with a space therebetween.

5. 5. The toner classifying device according to claim 4, wherein the liner has a surface facing the dispersion rotor, the surface being provided with grooves.

6. A toner manufacturing method including a classification step of classifying particles to be classified using a toner classifier, The toner classification device comprises: A toner classifying device having a classification rotor, The classification rotor has a plurality of blades extending from a rotation center side to an outer periphery side of the classification rotor, The plurality of blades are arranged at predetermined intervals from one another, The interval forms an opening toward a rotation center region of the classifying rotor, the blades are provided so as to be located upstream in the rotation direction of the classifying rotor from the end of the classifying rotor on the rotation center side toward the end of the classifying rotor on the outer periphery side, The blade has a bent portion, In a cross section of the classification rotor cut in a direction perpendicular to the rotation axis of the classification rotor, (i) an angle θ1 formed by a straight line connecting the rotation center of the classification rotor and the end of the blade on the rotation center side and a straight line connecting the end of the blade on the rotation center side and the bent portion of the blade is 30° to 65°; (ii) when the distance from the rotation center of the classifying rotor to the outer circumferential end of the blade is L1, the distance from the rotation center of the classifying rotor to the rotation center side end of the blade is L2, and the distance from the rotation center of the classifying rotor to the bent portion of the blade is L3, the following formula is satisfied: 0.65≦(L3-L2) / (L1-L2)≦0.85 (iii) an angle θ2 formed by a line connecting the rotation center side end of the blade and the bent portion of the blade and a line connecting the bent portion of the blade and the outer periphery side end of the blade is 5° to 25°; (iv) the sum of θ1 and θ2 is 55° to 85° A method for producing a toner.

7. 7. The method for producing a toner according to claim 6, wherein the sum of θ1 and θ2 is 65° to 85°.

8. The toner classification device comprises: A main body casing; A guide means is installed in a state in which at least a part of the classifying rotor is covered; a particle inlet formed on a side surface of the main casing for introducing particles to be classified and a particle supplying means having the particle inlet; a fine powder discharge port and a classified particle extraction port formed on a side surface of the main casing for discharging the classified particles from which fine powder has been removed outside the main casing; a dispersion rotor, which is a rotor attached to a central rotating shaft within the main casing and has a dispersion hammer on a side surface of the rotor facing the classifying rotor; The method for producing a toner according to claim 6 or 7, further comprising:

9. The method for producing a toner according to claim 8 , further comprising a liner fixedly disposed around the periphery of the dispersing rotor with a space therebetween.

10. The method for producing a toner according to claim 9 , wherein a groove is provided on a surface of the liner facing the dispersion rotor.

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