JP2006146197A - Method for manufacturing electrostatic image developing toner and apparatus for pulverizing and classifying toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing toner in which coarse particles are hardly mixed and which can obtain a high-quality image. <P>SOLUTION: The method for manufacturing the electrostatic image developing toner is the method for manufacturing the electrostatic image developing toner by pulverizing a coarsely pulverized toner material including a resin and a colorant, and then performing the classification. The pulverization is performed by introducing the coarsely pulverized toner material into a mechanical pulverizing apparatus having a rotor 1 rotated around a rotational shaft 3 as the center and having recessed and protruded parts on the outer surface, a liner 2 fitted into the outer side thereof and having recessed and protruded parts on the inner surface, and a pulverization space formed between the outer surface of the rotor and the inner surface of the liner. The classification is performed by a multi-products simultaneous classifying apparatus utilizing the Coanda effect. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a method for producing a toner for developing an electrostatic charge image used in an electrophotographic method, an electrostatic recording method and the like, and a pulverizing and classifying device for toner.

  Conventionally, a method for producing a toner for developing an electrostatic charge image is obtained by mixing and kneading raw materials such as a resin and a colorant, passing through a cooling step, and then roughly pulverizing with a hammer-type pulverizer or the like to obtain an average of 100 to 100 μm of coarse particles A method of taking a pulverized product and then pre-pulverizing if necessary or directly pulverizing to obtain a pulverized product having an average particle diameter of about several μm to several tens of μm is employed. This pulverized product is separated into only a group of particles having a predetermined particle size distribution in the classification step, and is used as a toner for developing an electrostatic image.

  Conventionally, as a pulverizer for pulverizing the coarsely pulverized product, a jutt type pulverizer using a supersonic jet stream, a space formed between a rotor (rotor) rotating at a rapid speed and a stator (liner) An impact pulverizer that pulverizes by introducing a pulverized product is mainly used. As classifiers, airflow classifiers (DS classifier manufactured by Nippon Pneumatic Co., Ltd.), simultaneous multi-product classifiers (elbow jet manufactured by Nippon Steel Mining Co., Ltd.), zigzag classifiers, and the like are used.

As an industrial scale facility, a production line is usually composed of a combination of 1 to 2 crushers and 2 to 4 classifiers.
JP-A-63-249155 JP-A-3-59675

  By the way, in such a toner manufacturing method, it is difficult to produce toner efficiently by using a jet pulverizer to finely pulverize the coarsely pulverized toner because of its high power consumption and poor energy efficiency. On the other hand, the impact type pulverizer has high energy efficiency, but there is a problem that instantaneous heat generation during pulverization is large and coarse particles of, for example, 40 μm or more are mixed in the toner pulverized product. This coarse particle is removed as much as possible with a vibrating sieve in the subsequent classification process, but it collides with the inner wall of the classifier and bounces back or probabilistically jumps to the product side. It gets mixed in. The presence of the mixed coarse particles has a problem that bad phenomena such as filming and comet occur in the image quality.

  An object of the present invention is to provide a method for producing a toner having a sharp particle size distribution with less generation of coarse particles in a toner product. It is another object of the present invention to provide a toner manufacturing method capable of giving good image quality without causing adverse phenomena such as filming and comet. Another object of the present invention is to provide a toner pulverizing and classifying apparatus that consumes very little power and has high energy efficiency in addition to a simple apparatus configuration.

  In order to solve the above problems, a method for producing an electrostatic charge image developing toner according to the present invention comprises pulverizing a coarsely pulverized toner containing at least a resin and a colorant, and then classifying the toner to develop an electrostatic charge image developing toner. In the manufacturing method, the crushing is performed by rotating a rotor around a rotation axis and having a crushing blade on an outer surface, a liner fitted on the outside and having a crushing blade on an inner surface, an outer surface of the rotor, and the liner The toner coarsely pulverized product is introduced into an impact pulverizer having a pulverization space formed between the inner surface and the rotor blade of the impact pulverizer. When viewed in a cross-section at right angles, the rotor is formed into a continuous wave shape with a substantially triangular shape inclined in one circumferential direction of the rotor. Direction and A substantially triangular shape inclined in the opposite direction is formed into a continuous wave shape, and the long side portion and the short side portion of each crushing blade of the rotor and the liner are inclined in the same direction as the inclination direction of the crushing blade, The rotor is configured to rotate at a peripheral speed of 50 to 180 m / s.

  The pulverizing and classifying apparatus for toner according to the present invention is an apparatus for pulverizing and classifying a coarsely pulverized toner containing at least a resin and a colorant, and has a pulverizing blade on an outer surface that rotates about a rotation shaft. A rotor and a liner that is fitted on the outer side with a space and has a pulverizing blade on the inner surface, and an impact pulverizer in which a gap between the rotor and the liner is a pulverizing space. And the pulverization blade of the rotor of the impact pulverizer is formed in a wave shape in which substantially triangular shapes inclined in one circumferential direction of the rotor are continuous when viewed in cross-section perpendicular to the rotation axis, The pulverizing blade of the liner is formed in a wave shape in which a substantially triangular shape inclined in a direction opposite to the circumferential direction is formed in a cross-sectional view perpendicular to the rotation axis, and the long sides of the pulverizing blades of the rotor and the liner Department and short side Is inclined to tilt in the same direction as the direction of the pulverizing blade, moreover, the rotor is characterized by being configured so as to rotate at a peripheral speed 50~180m / s.

  According to the present invention, it is possible to provide a production method for obtaining a toner having a sharp particle size distribution with few coarse particles on an industrial production scale with a simple apparatus configuration.

  The present invention is described in detail below. In the toner manufacturing method of the present invention, a normal manufacturing method can be adopted except for the pulverization and classification steps. As a normal production method, first, toner raw materials are mixed, kneaded with a melt extruder or the like, extruded into a plate shape, and cooled and solidified pellets are obtained. As the toner raw material, a binder resin and a colorant are used as essential components. For example, a charge control agent and other toner property imparting agents can be used as necessary.

  As the binder resin, for example, various known resins suitable for the toner can be used. For example, styrene resin, vinyl chloride resin, rosin modified maleic acid resin, phenol resin, epoxy resin, polyester resin, polyethylene resin, polypropylene resin, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate resin, xylene Resin, polyvinyl butyral resin, polycarbonate resin, etc. are mentioned. Two or more of these resins can be used in combination. In particular, it is preferable to use a styrene resin, a saturated or unsaturated polyester resin, and an epoxy resin as the main resin.

  And as for the glass transition temperature of said binder resin, it is preferable that the transition start temperature (inflection point) when measured by a thermal analysis method (a suggestion thermal analyzer, a suggestion scanning calorimetry analyzer, etc.) is 50 degreeC or more. . When the glass transition temperature is less than 50 ° C., when the toner is left for a long time at a high temperature of 40 ° C. or more, the toner is agglomerated or fixed, causing a problem in use. As the colorant for toner, various known colorants can be used. For example, carbon black, nigrosine, benzidine yellow, quinacridone, rhodamine B, phthalocyanine blue and the like are preferably used. The colorant is generally used in a proportion of 0.1 to 30 parts by weight, preferably 3 to 15 parts by weight per 100 parts by weight of the resin.

  As the charge control agent, various known charge control agents can be used. For example, a positive charge control agent such as a quaternary ammonium salt, a nigrosine dye, a triphenylmethane dye, a styrene-aminoacrylate copolymer, or a polyamine resin, or a negative charge control agent such as a monoazo metal complex salt can be used. The charge control agent is usually used at a ratio of 0.1 to 10 parts by weight per 100 parts by weight of the resin.

  As various toner property imparting agents, for example, polyalkylene waxes such as polyethylene wax and polypropylene wax can be used to prevent offset. In addition, inorganic fine particles such as titania, alumina, and silica can be used to improve fluidity and aggregation resistance. These toner property-imparting agents are usually used at a ratio of 0.1 to 10 parts by weight per 100 parts by weight of the resin.

  Further, when the toner is a magnetic toner, it can contain magnetic particles such as ferrite and magnetite, as well as alloys or compounds containing ferromagnetic elements such as iron, cobalt, and nickel. The magnetic particles are usually used at a ratio of 20 to 70 parts by weight per 100 parts by weight of the binder resin. Next, the cooled and solidified pellet-like toner is coarsely pulverized by a coarse pulverizer such as a hammer type pulverizer so that the weight average particle diameter is about 100 μm to 3000 μm, preferably about 300 μm. Here, the weight average particle size is a median value particle size of particle size-weight distribution, and can be measured by, for example, a Cole Counter manufactured by Coulter Electronics.

  In the present invention, in the step of further pulverizing the toner coarsely pulverized product thus obtained, the toner coarsely pulverized product is introduced into an impact pulverizer having a specific improved outlet, and the weight average particle size is several μm to several tens of μm. , Preferably pulverized to 3 to 20 μm. In order to increase the pulverization efficiency, two or more impact pulverizers can be used or combined with a jet pulverizer.

  As shown in FIG. 1, the principle of the impact pulverizer is that a cylindrical rotor (1) that rotates at a rapid speed by a rotating shaft (3) and a fixed or rotating liner (2) outside thereof are fine gaps. The material to be crushed is fed from the charging port (4) and transported through the pulverizing space which is a minute gap (8) divided by the rotor (1) and the liner (2). In the process, it is crushed and discharged from the outlet (5).

  The outer surface of the rotor of the impact pulverizer and the inner surface of the liner are provided with uneven portions (pulverization blades), and various shapes have been proposed. The impact pulverizer used in the present invention In particular, as shown in FIG. 2, one having a corrugated sharp grinding blade on at least one of the rotor outer surface and the liner inner surface, preferably both, is preferably used. Specifically, as shown in FIG. 2, the crushing blade of the rotor of the impact crusher has a continuous wave of substantially triangles inclined in one circumferential direction of the rotor when viewed in a cross-section perpendicular to the rotation axis. When the cross section of the liner pulverizing blade is formed in a shape perpendicular to the rotation axis, the crushed blades of the rotor and the liner are formed in a continuous wave shape with substantially triangular shapes inclined in the opposite direction to the circumferential direction. The long side portion and the short side portion of the blade are inclined in the same direction as the inclination direction of the grinding blade.

  Now, in the conventional pulverizer, as shown in the enlarged view of the outlet portion of the pulverizing space in FIG. 3, it is normal that the liner length extends about 10 to 20 mm longer than the rotor length at the outlet portion. It was. However, as a result of investigations by the present inventors, it has been found that the generation of coarse particles is mainly caused by uneven grooves at the outlet portion of the liner. Then, by smoothing at least a part of the surface on the outlet side of the liner, that is, by providing a smooth portion without the uneven portions (grooves) provided on the liner surface, coarse particles mixed into the product are markedly reduced. It has been found that it decreases. Probably in the conventional structure, at the exit part of the grinding space where the temperature of the object to be crushed is the highest and the speed of moving in the machine is abrupt, in the exit part of the liner, especially in the groove (uneven part) in the extension part It is considered that toner powder melted and softened by heat generated during pulverization adhered and grew to generate coarse particles.

  As the method of providing a smooth portion on at least a part of the surface of the liner at the exit portion of the pulverization space of the present invention, various forms are conceivable. For example, as shown in FIG. 4, a smooth portion is provided on the surface in the range of 0.1 mm to 200 mm, preferably 10 mm to 100 mm, and further 40 mm to 70 mm (a + b in FIG. 4) from the final end of the liner. Shape. In particular, the smooth portion is preferably a planar shape with the uneven portion removed as shown in FIG. Further, it is preferable not only to make the surface of the liner extended portion only a smooth portion, but also to make the surface of the liner facing the surface of the rotor a smooth portion. It is particularly preferable that the smooth portion is in the range (a) of 0.1 mm to 100 mm, preferably 10 mm to 70 mm, and 30 to 50 mm from the final end of the opposing rotor in the direction of the inlet. Note that the preferable range of the smooth portion varies depending on the size of the apparatus.

  The gap (8) provided between the rotor and the liner is usually several mm or less, but for use in the toner production method of the present invention, it is 0.1 mm to 5 mm, preferably 0.3 to 3.0 mm. Furthermore, it is preferable to set it as the range of 0.5-2.5 mm and 1.0-2.0 mm. This gap means the distance between the crest of the rotor crushing blade and the crest of the liner crushing blade. The operating conditions of the other impact pulverizers are selected as appropriate, but the atmospheric temperature is 30 to 50 ° C., and the rotational peripheral speed of the rotor is 50 to 180 m / s, preferably 60 to 140 m / s. The toner processed by the pulverizer and discharged from the discharge port is then subjected to a normal classification process to collect toner having a predetermined particle diameter of about 3 to 20 μm, preferably 5 to 15 μm.

  As the classifier, it is preferable to employ a multi-product simultaneous classifier (Elbow Jet manufactured by Nittetsu Mining Co., Ltd.) utilizing the Coanda effect, particularly in that coarse powder, medium powder, and fine powder can be simultaneously divided with high accuracy. The obtained coarse powder and fine powder other than the predetermined particle diameter can be circulated and reused in the production process. For example, the coarse powder can be circulated and re-pulverized in the pulverization process, and the fine powder can be circulated and used in the mixing process or the melt-kneading process together with the raw material powder.

  The toner obtained as described above is further subjected to a step of externally adding various known external additives, and then filled into a predetermined container to be commercialized.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited at all by the following examples, unless the summary is exceeded.

Example 1:
The exit shown in FIG. 4 was improved by mixing the raw materials shown in Table 1 and mixing the flakes (average particle size around 300 μm) obtained by mixing, kneading, and coarse pulverization at a rate of 200 kg / h. Is pulverized at an atmospheric temperature of 50 ° C. or less and a rotor (rotary body) rotation speed of 3200 rpm with an impact pulverizer having a part (turbo industry Turbomill T-800RS type). EJ-45-3S type) to obtain a product toner particle group having an average particle diameter of 10 μm.

  The generation rate of coarse particles of 40 μm or more contained in the pulverized product before classification at this time is 0.07%, and the generation rate of the coarse powder generated by the conventional non-improved pulverizer shown in Comparative Example 1 is 0.28%. 1/4 of that. 4 parts of the toner obtained by this method and 100 parts of a carrier having ferrite powder as a core material were mixed and stirred, and the developer obtained was subjected to a live-action test using a copying machine using an organic photoconductor as a photoreceptor. . The replenishment toner used in the actual shooting test is the same toner as that used in the developer.

  As a result, the actual image quality such as copy density and fog was good, and there was no occurrence of filming and comet, and the toner and developer were of excellent quality.

Comparative Example 1:
Using the same coarsely pulverized toner as in Example 1, a toner product was obtained in the same manner as in Example 1 except that an impact pulverizer whose pulverization space outlet portion was not improved as shown in FIG. 3 was used.

  At this time, the generation rate of coarse particles of 40 μm or more contained in the pulverized product before classification was 0.28%. Using this toner, a live-action test was conducted in the same manner as in Example 1. As a result, fog and black spots were frequently generated and the image quality was unsatisfactory.

Example 2:
Impact improved by mixing the raw materials shown in Table 2 and mixing and kneading and coarsely pulverizing flakes (average particle size around 300 μm) at a rate of 200 kg / h at the exit portion of the pulverization space as shown in FIG. Is pulverized by an atmospheric pulverizer (Turbo Industry Co., Ltd. turbo mill T-800RS type) at an atmospheric temperature of 50 ° C. or less and a rotor (rotary body) rotation speed of 3300 rpm, and then the pulverized product is elbow jet classifier (EJ-45- 3S type) to obtain a product toner particle group having an average particle diameter of 10 μm.

  The generation rate of coarse particles of 40 μm or more contained in the pulverized product before classification at this time is 0.07%, and the generation rate of coarse powder generated by the conventional non-improved pulverizer shown in Comparative Example 2 is 0.24%. 1/3. 4 parts of the toner obtained by this method and 100 parts of a carrier having ferrite powder as a core material were mixed and stirred, and the developer obtained was subjected to a live-action test using a copying machine using an organic photoconductor as a photoreceptor. . The replenishment toner used in the actual shooting test is the same toner as that used in the developer.

  As a result, the actual image quality such as copy density and fog was good, and there was no occurrence of filming and comet, and the toner and developer were of excellent quality.

Comparative Example 2:
Using the same coarsely pulverized toner as in Example 2, a toner product was obtained in the same manner as in Example 2 except that an impact pulverizer whose pulverization space outlet portion was not improved as shown in FIG. 3 was used.

  At this time, the generation rate of coarse particles of 40 μm or more contained in the pulverized product before classification was 0.24%. Using this toner, a live-action test was conducted in the same manner as in Example 1. As a result, fog and black spots were frequently generated and the image quality was unsatisfactory.

Schematic cross-sectional view of a general impact mill Enlarged view of the longitudinal section of the rotor and liner of the A-A line of the impact crusher of FIG. Cross-sectional enlarged view of the crushing space outlet of a conventional impact crusher An example of an enlarged cross-sectional view of the pulverization space outlet of the impact pulverizer of the present invention

Explanation of symbols

1: Rotor 2: Liner 3: Rotating shaft 4: Insertion port 5: Discharge port 6: Liner uneven part (grinding blade)
7: Rotor irregularities (grinding blades)
8: Crushing space

Claims (10)

  In a method for producing a toner for developing an electrostatic charge image by pulverizing a coarsely pulverized toner containing at least a resin and a colorant, the pulverization rotates about a rotation axis and has a pulverization blade on an outer surface. Coarse toner pulverization in an impact pulverizer having a rotor, a liner fitted on the outside and having a pulverization blade on the inner surface, and a pulverization space formed between the outer surface of the rotor and the inner surface of the liner When the grinding blade of the rotor of the impact type grinding machine is viewed in cross-section perpendicular to the rotation axis, a substantially triangular shape that is inclined in one circumferential direction of the rotor is continuous. The pulverizing blade of the liner is formed into a wave shape in which a substantially triangular shape tilted in a direction opposite to the circumferential direction is formed when viewed in cross-section perpendicular to the rotation axis, the rotor and the rotor. The long side portion and the short side portion of each crushing blade of the inertia are inclined in the same direction as the inclination direction of the crushing blade, and the rotor is configured to rotate at a peripheral speed of 50 to 180 m / s. A method for producing a toner for developing an electrostatic charge image.   2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein a smooth portion is provided on at least a part of the surface of the liner at the toner outlet portion of the pulverization space.   The method for producing a toner for developing an electrostatic charge image according to claim 2, wherein the smooth portion of the liner protrudes from the rotor.   The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 3, further comprising a corrugated acute angle grinding blade on at least one of the outer surface of the rotor and the inner surface of the liner.   The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 4, wherein a gap provided between the rotor and the liner is 0.1 to 5 mm.   A device for pulverizing and classifying a coarsely pulverized toner containing at least a resin and a colorant, the rotor having a pulverizing blade on the outer surface and rotating around a rotating shaft, and a space outside the rotor. And a liner having a pulverizing blade on the inner surface thereof, comprising an impact pulverizer in which a gap between the rotor and the liner is a pulverization space, and the rotor of the impact pulverizer When the pulverization blade is viewed in cross-section perpendicular to the rotation axis, the pulverization blade of the liner is formed in a wave shape in which a substantially triangular shape inclined in one circumferential direction of the rotor is continuous. When viewed, a substantially triangular shape inclined in the opposite direction to the circumferential direction is formed into a continuous wave shape, and the long side portion and the short side portion of each crushing blade of the rotor and the liner are inclined directions of the crushing blade. Inclined in the same direction as Moreover, the rotor is a toner for pulverizing and classifying apparatus characterized by being configured so as to rotate at a peripheral speed 50~180m / s.   The toner pulverizing and classifying apparatus according to claim 6, wherein a smooth portion is provided on at least a part of the surface of the liner at the toner outlet portion of the pulverizing space.   The toner pulverizing and classifying apparatus according to claim 7, wherein the smooth portion of the liner protrudes from the rotor.   9. The pulverizing and classifying device for toner according to claim 6, further comprising a corrugated sharp pulverizing blade on at least one of the outer surface of the rotor and the inner surface of the liner.   The toner pulverizing and classifying apparatus according to any one of claims 6 to 9, wherein a gap provided between the rotor and the liner is 0.1 to 5 mm.

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