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EP-4450151-B1 - HIGH-SHEAR MIXING APPARATUS

EP4450151B1EP 4450151 B1EP4450151 B1EP 4450151B1EP-4450151-B1

Inventors

  • KIM, TAEGON
  • KIM, KI TAE
  • KIM, SUNG SIK
  • PARK, JAE SEONG
  • NAM, HEE JEONG
  • HAH, HOEJIN
  • SONG, MIN SANG

Dates

Publication Date
20260513
Application Date
20230925

Claims (17)

  1. A high shear mixing apparatus (500), comprising: a mixing screw (10) and a housing (20) receiving the mixing screw (10); wherein the housing (20) includes a nozzle (22) provided at a distal end thereof and a hopper (24) in communication therewith, wherein the mixing screw (10) includes a rotating shaft (12) and blades (14) provided on an outer surface of the rotating shaft (12), wherein the rotating shaft (12) has a first tapered portion (12a) having a gradually increasing outer diameter in a direction toward the nozzle (22), a kneading portion (12b) having a uniform outer diameter or a gradually increasing outer diameter in the direction toward the nozzle (22), and a second tapered portion (12c) having a gradually decreasing outer diameter in the direction toward the nozzle (22) in this order, and wherein the blades (14) comprise first spiral blades (14a) disposed on an outer surface of the first tapered portion (12a), second spiral blades (14b) disposed on an outer surface of the kneading portion (12b), and third spiral blades (14c) disposed on an outer surface of the second tapered portion (12c), characterized in that the first spiral blades (14a) and the second spiral blades (14b) are independently formed, a pitch of the first spiral blades (14a) is larger than a pitch of the second spiral blade (14b), and the first spiral blades (14a) and the second spiral blades (14b) are spirally wound in a same direction about the rotating shaft (12)and, that an acute angle of the second spiral blades (14b) is larger than an acute angle of the first spiral blades (14a) based on an acute angle formed by the spiral blades with respect to a cross-section perpendicular to a center axis of the rotating shaft (12), and that the second spiral blades (14b) comprise three or more independent blades (14) superimposed on the outer surface of the kneading portion (12b).
  2. The high shear mixing apparatus (500) of claim 1, wherein the second spiral blades (14b) and third spiral blades (14c) are spirally wound in a same direction about the rotating shaft (12).
  3. The high shear mixing apparatus (500) of claim 2, wherein the third spiral blades (14c) comprise three or more independent blades (14) superimposed on the outer surface of the second tapered portion (12c).
  4. The high shear mixing apparatus (500) of claim 3, wherein the second spiral blades (14b) and third spiral blades (14c) are provided independently of each other.
  5. The high shear mixing apparatus (500) of claim 3, wherein the second spiral blades (14b) extend to the outer surface of the second tapered portion (12c) to form the third spiral blades (14c).
  6. The high shear mixing apparatus (500) of claim 5, wherein a gap is positioned between the second spiral blades (14b) and the third spiral blades (14c), wherein the gap is positioned between a terminal end of the kneading portion (12b) and a front end of the second tapered portion (12c) of the rotating shaft (12).
  7. The high shear mixing apparatus (500) of claim 3, wherein the three or more independent blades (14) provided in the second tapered portion (12c) are formed up to a periphery of a distal surface of the second tapered portion (12c) toward the nozzle (22).
  8. The high shear mixing apparatus (500) of claim 7, wherein a diameter of the distal surface of the second tapered portion (12c) in the rotating shaft (12) toward the nozzle (22) is from 0.5 to 2.0 times as large as an inner diameter of the nozzle (22).
  9. The high shear mixing apparatus (500) of claim 1, wherein the rotating shaft (12) continuously comprises the first tapered portion (12a) having a gradually increasing outer diameter in a direction toward the nozzle (22), the kneading portion (12b) having the uniform outer diameter or the gradually increasing outer diameter from a maximum outer diameter of the first tapered portion (12a), and the second tapered portion (12c) having a gradually decreasing outer diameter from an end of the kneading portion (12b).
  10. The high shear mixing apparatus (500) of claim 1, wherein a space between the outer surface of the first tapered portion (12a) of the rotating shaft (12) and the housing (20) is gradually reduced toward the nozzle (22), a space between the outer surface of the kneading portion (12b) and the housing (20) is gradually reduced or kept uniform toward the nozzle (22), and a space between the second tapered portion (12c) and the housing (20) is kept uniform or gradually reduced.
  11. The high shear mixing apparatus (500) of claim 1, wherein a length of the first tapered portion (12a), a length of the kneading portion (12b), and a length of the second tapered portion (12c) on the rotating shaft (12) are in a ratio of 1 : 0.1 to 0.4 : 0.2 to 0.5.
  12. The high shear mixing apparatus (500) of claim 3, wherein an acute angle of the second spiral blades (14b) is less than or equal to an acute angle of the third spiral blades (14c) based on an acute angle formed by the spiral blades with respect to a cross-section perpendicular to the center axis of the rotating shaft (12).
  13. The high shear mixing apparatus (500) of claim 3, wherein the third spiral blades (14c) have a maximum pitch at a starting point of the second tapered portion (12c) abutting the kneading portion (12b), a minimum pitch at a distal surface of the second taper toward the nozzle (22), and the pitch gradually decreases along the rotating shaft (12) toward the nozzle (22).
  14. The high shear mixing apparatus (500) of claim 3, wherein a perpendicular cross-section in a direction wound about the rotating shaft (12) of the first spiral blades (14a) includes two height-forming edges, wherein one of the height-forming edges toward the nozzle (22) forms an acute angle of 30 to 80 degrees with respect to the center axis of the rotating shaft (12) in a direction opposite the nozzle (22).
  15. The high shear mixing apparatus (500) of claim 14, wherein a perpendicular cross-section in a direction wound about the rotating shaft (12) of the second spiral blades (14b) includes two height-forming edges, wherein one of the height-forming edges toward the nozzle (22) forms an acute angle of 40 to 80 degrees with respect to the center axis of the rotating shaft (12) in a direction opposite the nozzle (22).
  16. The high shear mixing apparatus (500) of claim 15, wherein a perpendicular cross-section in a direction wound about the rotating shaft (12) of the third spiral blades (14c) includes two height-forming edges, wherein one of the height-forming edges toward the nozzle (22) forms an acute angle of 40 to 80 degrees with respect to the center axis of the rotating shaft (12) in the direction opposite the nozzle (22).
  17. The high shear mixing apparatus (500) of claim 1, wherein the high shear mixing apparatus (500) is configured to be used for high shear mixing of a mixture for fabricating a dry electrode comprising a fibrillizable polymer as a binder so as to micro-fibrillate the fibrillizable polymer.

Description

[Technical Field] The present application claims the benefit and priority to Korean Patent Application No. 10-2022-0121462, filed September 26, 2022. The present invention relates to a high shear mixing apparatus, and more particularly to a high shear mixing apparatus used to fabricate dry electrodes for a secondary battery. [Related Art] Stirring devices are used in various paste manufacturing facilities and for fine mixing of chemical raw materials, such as inks, pigments, paints, cosmetics, pharmaceuticals and coatings, various coatings, abrasives, ceramic or metal powders, or various electronic materials (PZT, dielectric, MLCC, Ferrite, display materials). As a stirring device, a planetary mixer or twin screw extruder, which uses blades and rotors to stir high-viscosity materials in a container, is used, especially for stirring high-viscosity materials. On the other hand, with the expansion and development of secondary battery applications, improvements in low resistance, high capacity, mechanical properties, and productivity of electrodes are continuously required, and the need for high shear mixing of electrode fabrication mixtures is also increasing. Specifically, a technology for fabricating dry electrode films by mixing binders and conductive materials without liquid media such as solvents or dispersants, and then passing the powder mixture through a rolling roll is being actively developed, and high shear mixing is being applied to fabricate such electrodes. The high shear mixing methods described above use binders called "fibrillizable binders" or "fibril-forming binders," which, when subjected to high shear mixing in a mixture containing such binders, micro-fibrillate and bind the active and conductive materials. Conventional planetary mixers and twin screw extruders are used for the above high shear mixing method. However, during this high shear mixing process, the fibrillizable polymer becomes a chewing gum-like state, which puts a large load on the planetary mixer or twin screw extruder, and damage to the equipment often occurs. In order to prevent such equipment damage, a method of reducing the shearing force is considered, but in this case, the fibrillizable polymer is not well fibrillized. Therefore, it is very difficult to build a large-scale mass production system for fabricating dry electrodes for secondary batteries with conventional high shear mixing apparatus. [Prior Art Reference] [patent reference] Korean Laid-open Publication No. 10-2011-0117902JP 2002 224891 A describes an operating method where the wastes are clogged in a casing in spite of attempt to reversely rotate a screw body for dewatering, after attempting, for example, three times, the reverse rotation, stop and forward rotation, open an opening/closing cap disposed at a rear end of the opening/closing case by an opening/closing cylinder device, then reversely rotate the screw body for dewatering and take out the wastes in the clogged state out of a discharge aperture. [Detailed Description of the Invention] [Technical Problem] The present invention is designed to solve the above problems of the prior art, and aims to provide a high shear mixing apparatus that can efficiently mix materials without generating overload when mixing materials by high shearing force. In particular, it is an object to provide a high shear mixing apparatus capable of efficiently micro-fibrillating the polymer without generating an overload during high shear mixing of a mixture for fabricating a dry electrode comprising a fibrillizable polymer as a binder. [Technical Solution] The present invention is defined according to the subject matter of the appended independent claim. Particular embodiments are given by the additional features of the appended dependent claims. In order to accomplish the above objectives, the present invention provides a high shear mixing apparatus, comprising: a mixing screw and a housing receiving the mixing screw; wherein the housing includes a nozzle provided at a distal end thereof and a hopper in communication therewith, wherein the mixing screw includes a rotating shaft and blades provided on an outer surface of the rotating shaft, wherein the rotating shaft has a first tapered portion having a gradually increasing outer diameter in a direction toward the nozzle, a kneading portion having a uniform outer diameter or a gradually increasing outer diameter in a direction toward the nozzle, and a second tapered portion having a gradually decreasing outer diameter in a direction toward the nozzle in this order, and wherein the blades comprise first spiral blades disposed on an outer surface of the first tapered portion, second spiral blades disposed on an outer surface of the kneading portion, and third spiral blades disposed on an outer surface of the second tapered portion. The first spiral blades and the second spiral blades are independently formed, a pitch of the first spiral blades is larger than a pitch of the sec