Magnetic foreign particle separation device and magnetic foreign particle separation method

Abstract

To provide a magnetic foreign particle separation device and magnetic foreign particle separation method with high removal efficiency of magnetic foreign particles contained in powder.SOLUTION: A magnetic foreign particle separation device comprises: a magnetic field generation unit that includes at least one magnet selected from a group consisting of superconducting bulk magnets and superconducting solenoid magnets, and generates a magnetic field; and a flow path member that has a tubular flow path through which a dispersion liquid in which a powder containing magnetic foreign particles is dispersed in a liquid medium flows, the flow path being arranged such that the dispersion liquid passes linearly through the magnetic field multiple times.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a magnetic foreign matter powder separation device and a magnetic foreign matter powder separation method. [Background technology]

[0002] In semiconductor packaging, the insulating performance of non-conductive materials used in electronic components or their substrates, such as non-conductive sealants for sealing semiconductor elements, heat conductive sheets, and heat dissipation fillers, can be degraded by the presence of conductive foreign particles, mainly composed of iron, contained in the raw materials. For example, the presence of conductive foreign particles can cause quality assurance problems due to short circuits between element circuits. Since the circuit width of semiconductor elements is often extremely narrow, it is necessary to remove as many conductive foreign particles as possible, even if they are very fine, as they can electrically bridge the circuit width. Similarly, a decrease in the dielectric strength of an interlayer insulating film can reduce the reliability of the element.

[0003] However, most non-conductive powder materials that are commonly used as raw materials undergo mechanical crushing, screening with a metal mesh, and other processes during the manufacturing process that can easily result in the inclusion of conductive foreign particles such as iron and stainless steel. For this reason, even high-purity non-conductive powder materials often contain trace amounts of conductive foreign particles. In order to improve the quality of this non-conductive powder material, it is desirable to separate and remove trace amounts of conductive foreign particles from the raw materials. Most of these conductive foreign particles are magnetic conductors whose main component is iron, and most non-conductive materials are non-magnetic powder materials, so a method of separating them using magnetism is effective for removing them.

[0004] The following examples are presented as prior art techniques for separating magnetic foreign powder from non-magnetic raw materials. In general magnetic separation of powder materials, for example, a rod-shaped magnetic object containing a permanent magnet is placed in the powder flow path, and the magnetic substance contained therein is attracted and held. After a certain period of time has passed, the object is removed from the flow path, and the magnetic substance or powder that has been attracted to and accumulated on the surface is removed by wiping it off (for example, Patent Document 1). Furthermore, Patent Document 2 describes a method for removing Fe-based metallic foreign matter that has become mixed into the slurry using a die head equipped with an iron removing means. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-269006 A [Patent Document 2] JP 2010-135238 A Summary of the Invention [Problem to be solved by the invention]

[0006] If the non-magnetic powder used as the non-magnetic material contains magnetic foreign matter, the magnetic foreign matter powder, which is a very small amount of magnetic conductor, is generally not easily adsorbed by a magnetic field. Therefore, high separation efficiency is desired in magnetic separation methods that use a magnetic field. An object of one embodiment of the present disclosure is to provide a magnetic foreign matter powder separation device and a magnetic foreign matter powder separation method that are highly effective in removing magnetic foreign matter powder contained in powder. [Means for solving the problem]

[0007] Specific means for achieving the above object include the following aspects. <1> A magnetic field generating unit that generates a magnetic field, the magnetic field generating unit including at least one magnet selected from the group consisting of a superconducting bulk magnet and a superconducting solenoid magnet; a flow path member having a tubular flow path through which a dispersion liquid in which a powder containing magnetic foreign matter powder is dispersed in a liquid medium flows, the flow path being arranged so that the dispersion liquid passes through the magnetic field in a straight line a plurality of times; A magnetic foreign matter powder separation device having the above structure. <2> In a cross section perpendicular to the flow direction of the dispersion liquid in the flow channel, the maximum height in the direction of the magnetic field is 1.2 mm to 10 mm. <1> The magnetic foreign matter powder separation device according to claim 1. <3> The method further includes an ultrasonic irradiation unit that irradiates the dispersion liquid with ultrasonic waves before the dispersion liquid passes through the magnetic field. <1> or <2> The magnetic foreign matter powder separation device according to claim 1. <4> generating a magnetic field from a magnetic field generating unit including at least one magnet selected from the group consisting of a superconducting bulk magnet and a superconducting solenoid magnet; A dispersion liquid in which a powder containing magnetic foreign matter powder is dispersed in a liquid medium is passed through a tubular flow path arranged so that the dispersion liquid passes through the magnetic field in a straight line a plurality of times; The magnetic foreign matter powder separation method includes the steps of: <5> In a cross section perpendicular to the flow direction of the dispersion liquid in the flow channel, the maximum height in the direction of the magnetic field is 1.2 mm to 10 mm. <4> The magnetic foreign matter powder separation method according to claim 1 . <6> The flow rate of the dispersion is 100 cm / s or less. <4> or <5> The magnetic foreign matter powder separation method according to claim 1 . <7> The method further comprises irradiating the dispersion with ultrasonic waves before passing through the magnetic field. <4> ~ <6> 13. A magnetic foreign matter powder separation method according to claim 12. <8> The method further comprises dispersing the powder in the liquid medium to prepare the dispersion; the time from preparation of the dispersion to the first exposure of the dispersion to the magnetic field is 500 hours or less; <4> ~ <7> 13. A magnetic foreign matter powder separation method according to claim 12. Effect of the Invention

[0008] According to one embodiment of the present disclosure, a magnetic foreign matter powder separating device and a magnetic foreign matter powder separating method that are highly effective for removing magnetic foreign matter powder contained in powder are provided. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram showing an example of a magnetic foreign matter powder separation device according to a first embodiment. [Diagram 2] 2 is an enlarged view of the vicinity of the magnetic pole surface of the magnetic field generating unit in the magnetic foreign matter powder separating device of FIG. 1. [Diagram 3] FIG. 2 is a schematic diagram showing a flow path member having a spiral flow path. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In the present disclosure, a numerical range indicated using "~" includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in the present disclosure in stages, the upper or lower limit of one numerical range may be replaced by the upper or lower limit of another numerical range described in stages. Also, in the numerical ranges described in the present disclosure, the upper or lower limit of the numerical range may be replaced by the values ​​shown in the test examples. When an embodiment of the present disclosure is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. In addition, the size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this.

[0011] Hereinafter, the embodiments for carrying out the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless otherwise specified. The same applies to the numerical values ​​and their ranges, and do not limit the present disclosure. In addition, components having substantially the same functions are given the same reference numerals throughout the drawings, and duplicated explanations may be omitted.

[0012] [Magnetic foreign matter powder separation device and magnetic foreign matter powder separation method] A magnetic foreign matter powder separation device (hereinafter, also simply referred to as a "separation device") in one embodiment of the present disclosure includes a magnetic field generating unit that includes at least one magnet selected from the group consisting of superconducting bulk magnets and superconducting solenoid magnets and generates a magnetic field, and a flow path member that has a tubular flow path through which a dispersion liquid in which powder containing magnetic foreign matter powder is dispersed in a liquid medium flows, the flow path being arranged so that the dispersion liquid passes through the magnetic field in a straight line multiple times. The flow path is formed by the flow path member and is a space through which the dispersion liquid flows. If necessary, the separation device may further include a dispersion liquid storage section for storing the dispersion liquid, a transport section for transporting the dispersion liquid into the flow path, a dispersion liquid storage section for storing the dispersion liquid with the additional flow path, an ultrasonic irradiation section for irradiating ultrasonic waves to the dispersion liquid before it passes through the magnetic field, and the like.

[0013] A magnetic foreign matter powder separation method (hereinafter also referred to simply as a "separation method") in one embodiment of the present disclosure includes generating a magnetic field from a magnetic field generating unit including at least one magnet selected from the group consisting of superconducting bulk magnets and superconducting solenoid magnets, and flowing a dispersion liquid in which powder including magnetic foreign matter powder is dispersed in a liquid medium through a tubular flow path arranged so that the dispersion liquid passes through the magnetic field in a straight line multiple times. The above separation method may further include, as necessary, transporting the dispersion liquid contained in the dispersion liquid storage section by a transport section, collecting magnetic foreign matter powder captured on the wall surface of the flow path, irradiating ultrasonic waves to the dispersion liquid before it passes through the magnetic field, dispersing the powder in a liquid medium to prepare a dispersion liquid, and the like.

[0014] In the above separation device and separation method, a magnetic field is generated by at least one magnet selected from the group consisting of a superconducting bulk magnet and a superconducting solenoid magnet, and a flow path is arranged so that the dispersion passes through the magnetic field in a straight line multiple times. Therefore, the removal of magnetic foreign matter powder is higher than, for example, when the magnetic field generating source is a conventional permanent magnet, when the flow path is arranged so that the dispersion passes through the magnetic field only once, or when the flow path is arranged so that the dispersion passes through the magnetic field in a curved line multiple times. Furthermore, the high removal of magnetic foreign matter powder in the above separation device and separation method makes it possible to improve the quality of a wide range of non-magnetic powder materials, such as ceramics for insulating substrates, non-conductive shields, heat dissipation insulators, abrasive grains, and polishing agents. Hereinafter, an example of the separation device and separation method of the present disclosure will be described with reference to the drawings, but the separation device and separation method of the present disclosure are not limited thereto.

[0015] First Embodiment FIG. 1 is a schematic diagram showing an example of a separation device according to a first embodiment, and FIG. 2 is an enlarged view of the vicinity of a magnetic pole surface of a magnetic field generating unit in the separation device of FIG. 1 includes a dispersion liquid storage section 14 that stores a dispersion liquid 12 in which powder containing magnetic foreign matter powder is dispersed in a liquid medium, a flow path member 16 having a tubular flow path through which the dispersion liquid 12 flows, a pump 18 that is an example of a transport section that transports the dispersion liquid 12 into the flow path of the flow path member 16, a magnetic field generating section 20 that generates a magnetic field in a part of the flow path member 16, and a dispersion liquid storage section 22 that stores the dispersion liquid 12 that has passed through the flow path. In addition, a mounting table 28 that holds the flow path member 16 is provided on a side surface of the magnetic field generating section 20 such that a magnetic pole surface 24, which is the surface of the magnetic field generating section 20 facing the flow path member 16, and a surface of the mounting table 28 facing the flow path member 16 are continuous with each other.

[0016] (Magnetic field generating part) The magnetic field generating unit 20 includes a superconducting bulk magnet (hereinafter also referred to as a "bulk magnet"). Here, it is known that the magnetic force acting on magnetic foreign particles in magnetic separation generally depends on the strength of the magnetic field and its spatial gradient in the magnetic field space. In addition, the volume of each magnetic foreign particle and the magnitude of magnetization inherent to the substance are also greatly related to effective magnetic separation. Magnetic separation of powder materials with small magnetization and small volume per particle, such as paramagnetic materials, is generally difficult, and a stronger magnetic field and a steeper magnetic field space are required.

[0017] Since the magnetic field generating unit 20 uses a bulk magnet as a magnetic field generating means, the magnetic attraction force can be increased by utilizing the strong magnetic field and steep magnetic field gradient. Examples of bulk magnets include cylindrical, disk-shaped, or prismatic bulk magnets whose main composition is a high-temperature superconducting material called rare earth 123 phase, and which are formed by the growth of coarse crystals by the melting method. The bulk magnet is, for example, held in a vacuum-insulated state in a stainless steel vacuum container, cooled to an extremely low temperature range by a refrigerator to be in a superconducting state, and excited by an external pulse magnetic field or static magnetic field. Examples of excitation devices for exciting bulk magnets include superconducting solenoid magnets. Examples of excitation methods for exciting bulk magnets include a magnetic field cooling method and a pulse magnetization method. Examples of the cooling temperature of the bulk magnet include a temperature range lower than the superconducting transition temperature of the bulk magnet, for example, a temperature of 30K or lower.

[0018] The surface of the magnetic field generating unit 20 facing the flow path member 16 is a magnetic pole surface 24 from which magnetic field lines are generated. The magnetic field lines are generated from the magnetic pole surface 24 toward the flow path member 16. From the viewpoint of improving the removal performance of magnetic foreign matter powder, the strength of the magnetic field generated from the magnetic pole surface 24 of the magnetic field generating unit 20 is preferably 1.5 T or more, more preferably 2 T or more, and even more preferably 3 T or more. The strength of the magnetic field generated from the magnetic pole surface 24 of the magnetic field generating unit 20 is preferably as high as possible from the viewpoint of improving the removal performance of magnetic foreign matter powder, so that the upper limit is not particularly limited, and may be, for example, 6 T. The strength of the magnetic field can be measured using a Tesla meter (Lake Shore Cryotronics Inc. HGT-3010).

[0019] The separation device of this embodiment includes a magnetic field generating unit 20 that uses a bulk magnet as a magnetic field generating means, but is not limited to this. The separation device may include a magnetic field generating unit that uses a superconducting solenoid magnet as a magnetic field generating means, or may include a magnetic field generating unit that uses both a bulk magnet and a superconducting solenoid magnet as a magnetic field generating means. By including at least one magnet selected from the group consisting of a superconducting bulk magnet and a superconducting solenoid magnet in the magnetic field generating unit, the removal of magnetic foreign powder is improved compared to when the magnetic field generating unit includes only a conventional permanent magnet.

[0020] The magnetic field generating unit 20 preferably uses a bulk magnet as a magnetic field generating means. By using a bulk magnet, the magnetic field generating unit 20 itself can be small and can generate a strong magnetic field. In addition, since the magnetic field generating unit 20 itself is small, it is easy to adjust the distance between the magnetic field generating unit 20 and the flow path member 16, and the strong magnetic field and steep magnetic field gradient act on the dispersion liquid 12, which makes it easier to improve the removability of magnetic foreign matter powder.

[0021] The shape and size of the magnetic field generating unit 20 are not particularly limited. The magnetic pole surface 24 of the magnetic field generating unit 20 may be a flat surface or a curved surface. From the viewpoint of efficiently using the magnetic field generated from the magnetic pole surface 24, it is preferable that the magnetic pole surface 24 is a flat surface. The magnetic field generated by the magnetic field generating unit 20 may be a pulsed magnetic field or a static magnetic field. 1 includes only one magnetic field generating unit 20, but the present invention is not limited to this and may include two or more magnetic field generating units. When the separation device includes two or more magnetic field generating units, the flow path member 16 is arranged in at least one of the two or more magnetic field generating units so that the dispersion liquid 12 passes through the magnetic field generated from one magnetic pole surface 24 multiple times.

[0022] (Flow path components) The flow path member 16 has a tubular flow path through which the dispersion liquid 12 flows. The flow path is arranged so that the dispersion liquid 12 passes through a region of one magnetic field generated from the magnetic pole surface 24 of one magnetic field generating unit 20 multiple times. Here, an example of a flow path arranged so that the dispersion liquid 12 passes through one magnetic field region multiple times is flow path member 116 having a spiral flow path as shown in Fig. 3. In the flow path in flow path member 116 shown in Fig. 3, the dispersion liquid 12 passes through a magnetic field region generated from magnetic pole surface 124 in a curved manner. In contrast, the flow path member 16 of the present embodiment has a flow path arranged so that the dispersion liquid 12 passes through the region of one magnetic field generated from the magnetic pole surface 24 of one magnetic field generating unit 20 multiple times and in a straight line, as shown in Fig. 2. This improves the removability of magnetic foreign matter powder compared to when the dispersion liquid passes only once or when it passes in a curved line multiple times. It is not clear why the magnetic foreign matter powder is more easily removed when the dispersion liquid passes in a straight line multiple times than when the dispersion liquid passes in a curved line multiple times, but it is presumed that this is because the linear shape makes the flow of the dispersion liquid more orderly and less likely to become turbulent, making it easier for the magnetic foreign matter powder to be captured by the magnetic field.

[0023] The above-mentioned "straight line" is not limited to a straight line, but includes an approximately straight line. The radius of curvature of the approximately straight line is, for example, 0.1 m or more, preferably 0.5 m or more, and more preferably 1.0 m or more. The flow path has a plurality of passages 26 through which the dispersion liquid 12 passes through one magnetic field region, that is, the dispersion liquid 12 passes through one magnetic field a plurality of times. Furthermore, two or more of the passing parts 26 have a linear region among the multiple passing parts 26. That is, the dispersion liquid 12 passes through one magnetic field multiple times in a linear manner. When the flow path has three or more passing sections 26, it is sufficient that two or more of the passing sections 26 have linear regions, and the flow path may be composed of two or more passing sections 26 having linear regions and two or more passing sections 26 having no linear regions, or all of the passing sections 26 may have linear regions. The passing portion 26 having a linear region may be such that at least a portion of the passing portion 26 is linear, or a portion of the passing portion 26 may be curved, or the entire passing portion 26 may be linear. The length of the linear region in one passing portion 26 is preferably 50% or more of the length of the passing portion, more preferably 75% or more, even more preferably 90% or more, and particularly preferably 100%.

[0024] The number of passing parts 26 having linear regions can be 2 or more, and from the viewpoint of improving the removability of magnetic foreign matter powder, 2 or more is preferable, 3 or more is more preferable, 4 or more is even more preferable, and 6 or more is particularly preferable. There is no particular upper limit on the number of passing parts 26 having linear regions, and it may be 10 or less, 9 or less, or 8 or less. 2, the linear regions in the multiple passing sections 26 are arranged parallel to each other, but this is not limited thereto. Two or more linear regions may be arranged substantially parallel to each other, or may be arranged in a state of intersecting three-dimensionally. 2 is configured as a single-stage flow path member 16 that is arranged at approximately the same distance from the magnetic pole surface 24 of the magnetic field generating unit 20 and in a plane parallel to the magnetic pole surface 24, but is not limited to this. The multiple passing sections 26 may be configured as a two or more stage flow path member that is arranged at positions with different distances from the magnetic pole surface 24 of the magnetic field generating unit 20.

[0025] From the viewpoint of separation efficiency, the distance from the magnetic pole surface 24 to the linear region in the passage section 26 is preferably 25 mm or less, more preferably 10 mm or less, and even more preferably 5 mm or less. There is no particular lower limit to the distance from the magnetic pole surface 24 to the linear region in the passage section 26, and it may be 0.1 mm or more, or 1 mm or more. The distance from the magnetic pole surface 24 to the linear region in the passage section 26 refers to the distance from the surface of the magnetic pole surface 24 to the position closest to the magnetic pole surface 24 (i.e., the bottom of the flow path) in a cross section perpendicular to the flow direction of the dispersion liquid 12 in the flow path. The angle between the flow direction of the dispersion liquid 12 in the passage section 26 and the magnetic pole face 24 is preferably 5 degrees or less, and is more preferably approximately parallel.

[0026] The length of the linear region in one of the two or more passing sections 26 having linear regions is set according to the size of the magnetic pole face 24, and may be, for example, 6 cm or more from the viewpoint of improving the removability of magnetic foreign matter powder, and may be 6 cm to 10 cm, or may be 6 cm to 20 cm. The length of the linear region is the length in the flow direction of the dispersion liquid 12. It is presumed that when the length of the linear region in one passing section 26 is equal to or more than the lower limit, the flow of the dispersion liquid 12 is regulated in the passing section 26, and the magnetic foreign matter powder is easily captured by the magnetic field.

[0027] 2 is disposed so that the dispersion liquid 12 travels back and forth through a region of one magnetic field generated from one magnetic pole surface 24. Specifically, the flow path from when the dispersion liquid 12 passes through one passing section 26 until it reaches the next passing section 26 (hereinafter also referred to as the "inter-passing section flow path") is curved. The length of each inter-passage flow path is not particularly limited and may be, for example, 6 cm or more, and from the viewpoint of separation efficiency, is preferably 12 cm to 30 cm, and more preferably 12 cm to 20 cm. It is presumed that when the length of each inter-passage flow path is equal to or more than the above lower limit, the flow of the dispersion liquid 12 that has reached the next passing part 26 becomes more uniform, and the magnetic foreign matter powder is more likely to be captured by the magnetic field.

[0028] The cross-sectional shape of the flow path in the passing portion 26 is not particularly limited, and examples thereof include circular shapes such as a perfect circle and an ellipse, and rectangular shapes such as a square and a rectangle. The above cross-sectional shape is the shape of a cross section perpendicular to the flow direction of the dispersion liquid 12 in the flow path. From the viewpoint of separation efficiency, the maximum height of the flow path in the passing section 26 is preferably 1.2 mm to 10 mm, more preferably 1.2 mm to 5 mm, and even more preferably 1.2 mm to 3 mm. It is presumed that the shear stress caused by the dispersion liquid 12 is not too large and the magnetic foreign matter powder is easily captured by the magnetic field when the maximum height of the flow path is equal to or greater than the above lower limit. It is also presumed that the magnetic foreign matter powder is easily captured by the magnetic field when the maximum height of the flow path is equal to or less than the above upper limit, since the proportion of the dispersion liquid 12 passing through the area with a strong magnetic field increases among the dispersion liquid 12 passing through the passing section 26. The maximum height of the flow path refers to the maximum height in the direction of the magnetic field in a cross section perpendicular to the flow direction of the dispersion liquid 12 in the flow path. From the viewpoint of separation efficiency, the cross-sectional area of ​​the flow passage in the passage portion 26 is set to 5 mm 2 ~40mm 2 is preferred, and 10 mm 2 ~20mm 2 is more preferable, and 10 mm 2 ~15mm 2 The above-mentioned cross-sectional area of ​​the flow channel refers to the area of ​​a cross section perpendicular to the flow direction of the dispersion liquid 12 in the flow channel.

[0029] The material of the flow path member 16 is not particularly limited as long as it is a non-magnetic material, and examples of the material include resins such as silicone rubber, urethane rubber, fluororesin, nylon, soft vinyl, polyethylene, polypropylene, polyimide, etc.; glass; and metals such as brass, aluminum, etc. Among these, from the viewpoints of ease of processing the shape of the flow path and corrosion resistance, resins are preferred, and silicone rubber is more preferred.

[0030] In the separation device 10 shown in FIG. 1, the flow path member is installed on the magnetic pole surface 24 of the magnetic field generating unit 20 and the surface of the installation stand 28 so that the direction of the magnetic field generated from the magnetic field generating unit 20 is the direction of gravity, and the flow direction in the passing portion 26 of the flow path member 16 is a horizontal direction perpendicular to the direction of gravity, but is not limited to this. The flow direction in the passing portion 26 of the flow path member 16 may be any of the horizontal direction, the direction of gravity, and other directions (i.e., oblique directions), and is preferably approximately horizontal from the viewpoint of facilitating the capture of magnetic foreign matter powder and improving separation efficiency. In addition, the flow direction in the passing portion 26 of the flow path member 16 may be any of the perpendicular, parallel, and other directions (i.e., oblique directions) to the direction of the magnetic field, and is preferably approximately perpendicular to the direction of the magnetic field from the viewpoint of facilitating the capture of magnetic foreign matter powder and improving separation efficiency. The mounting base 28 is not particularly limited, and may be a plate-shaped mounting base or the like.

[0031] (Transport section, dispersion liquid storage section, and dispersion liquid storage section) The pump 18, which is an example of a transport section, transports the dispersion liquid 12 by pressure from one end to the other end of the flow path member 16. The transport section is not particularly limited as long as it takes in the dispersion liquid 12 into the flow path of the flow path member 16 and transports it from one end to the other end of the flow path member 16. The pressure applied to the dispersion liquid 12 by the pump 18 is, for example, in the range of 0.05 MPa to 0.4 MPa. The flow rate of the dispersion liquid 12 transported by the pump 18 is preferably 100 cm / s or less from the viewpoint of facilitating the capture of magnetic foreign matter powder and improving the removal of the magnetic foreign matter powder, and is more preferably 1 cm / s to 100 cm / s, and even more preferably 20 cm / s to 70 cm / s, from the viewpoint of achieving both improved removal of magnetic foreign matter powder and improved separation speed. In addition, the flow rate of the dispersion liquid 12 transported by the pump 18 is preferably 1 mL / s to 15 mL / s, and more preferably 3 mL / s to 10 mL / s, from the viewpoint of improving separation efficiency. The flow rate and flow rate of the dispersion liquid 12 are measured by calculation from the time required to transport a certain volume and the cross-sectional area of ​​the flow path.

[0032] In the dispersion liquid storage section 14, the dispersion liquid 12 is stored in a container. One end of a flow path member 16 is connected to the dispersion liquid 12 stored in the dispersion liquid storage section 14. Note that the dispersion liquid storage section 14 may include a stirring member 30 that stirs the stored dispersion liquid 12, as shown in FIG. In the dispersion liquid storage section 22, the dispersion liquid 12 that has passed through the flow path of the flow path member 16 is stored in a container. To the container of the dispersion liquid storage section 22, the other end of the flow path member 16 is connected. The container for storing the dispersion liquid 12 in the dispersion liquid storage section 14 and the container for storing the dispersion liquid 12 in the dispersion liquid storage section 22 may be any container capable of storing and storing the dispersion liquid 12, and are not particularly limited.

[0033] (Ultrasonic irradiation part) Although not shown, the separation device 10 may further include an ultrasonic irradiation unit that irradiates ultrasonic waves to the dispersion liquid 12 before it passes through the magnetic field. Ultrasonic waves are sound waves having a frequency of 20 kHz or more. The separator 10 has an ultrasonic irradiation section, which further improves the ability to remove magnetic foreign powder. The reason for this is unclear, but it is speculated that the irradiation of ultrasonic waves to the dispersion liquid 12 before it passes through the magnetic field breaks down aggregates of magnetic foreign powder particles and particles other than magnetic foreign powder contained in the dispersion liquid 12, making it easier for the broken down magnetic foreign powder to be captured by the magnetic field.

[0034] The ultrasonic irradiation section may irradiate ultrasonic waves to the dispersion liquid 12 before it is accommodated in the dispersion liquid accommodation section 14, may irradiate ultrasonic waves to the dispersion liquid 12 accommodated in the dispersion liquid accommodation section 14, or may irradiate ultrasonic waves to the dispersion liquid 12 in the flow path of the flow path member 16. When irradiating ultrasonic waves to the dispersion liquid 12 in the flow path of the flow path member 16, it is preferable to irradiate ultrasonic waves to the dispersion liquid 12 in the flow path of the flow path member 16 from the end on the dispersion liquid accommodation section 14 side to before it reaches the passing section 26.

[0035] The ultrasonic generator that generates ultrasonic waves in the ultrasonic irradiation unit is not particularly limited, and a commercially available one may be used. Specific examples of ultrasonic generators include standing wave type ultrasonic generators such as ultrasonic cleaners, horn type ultrasonic generators such as homogenizers, etc. The frequency of the ultrasonic waves irradiated to the dispersion liquid 12 may be, for example, 20 kHz to 1,000 kHz, and from the viewpoint of improving the removal of magnetic foreign matter powder, 25 kHz to 100 kHz is preferable. When an ultrasonic cleaner is used as the ultrasonic generator, the oscillation output of the ultrasonic generator is, for example, 20 W to 1500 W, and preferably 40 W to 600 W from the viewpoint of improving the removal performance of magnetic foreign matter powder. When ultrasonic waves are applied to the dispersion liquid 12 before it is accommodated in the dispersion liquid accommodation section 14, the duration of ultrasonic irradiation to the dispersion liquid 12 is, for example, 0.1 to 60 minutes, and from the viewpoint of improving the removal of magnetic foreign matter powder, 5 to 20 minutes is preferable. When ultrasonic waves are applied to at least one of the dispersion liquid 12 accommodated in the dispersion liquid accommodation section 14 and the dispersion liquid 12 in the flow path of the flow path member 16, ultrasonic irradiation may be performed continuously while the dispersion liquid 12 is being transported in the flow path.

[0036] 1 is a batch-type separation device in which one end of a flow path member 16 is connected to the dispersion liquid 12 contained in a dispersion liquid storage section 14 and the other end of the flow path member 16 is connected to a dispersion liquid storage section 22 different from the dispersion liquid storage section 14, but is not limited thereto. For example, the separation device may be a continuous-type separation device having a dispersion liquid storage section that serves as both a dispersion liquid storage section and a dispersion liquid storage section, in which one end of the flow path member 16 is connected to the dispersion liquid 12 contained in the dispersion liquid storage section and the other end of the flow path member 16 is also connected to the dispersion liquid storage section.

[0037] (dispersion) The dispersion liquid 12 is a liquid medium in which powder containing magnetic foreign matter is dispersed. The liquid medium is not particularly limited as long as it can pass through the flow path of the flow path member 16 when made into the dispersion liquid 12, and is selected depending on the type of powder. Examples of the liquid medium include water, organic solvents, and mixtures thereof. Examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and isopropyl alcohol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aromatic hydrocarbons such as benzene, toluene, and xylene; and aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane. oh The viscosity of the liquid medium at 25° C. is, for example, 0.5 mPa·s to 100 mPa·s, and from the viewpoint of separation efficiency, is preferably 0.5 mPa·s to 10 mPa·s, and more preferably 0.5 mPa·s to 5 mPa·s. The content of the liquid medium in the dispersion 12 is, for example, 10% by mass to 80% by mass relative to the entire dispersion 12, and from the viewpoint of separation efficiency, is preferably 20% by mass to 70% by mass, and more preferably 40% by mass to 65% by mass.

[0038] (Separation method) Next, a separation method using the separation device 10 shown in FIG. 1 will be described. First, the dispersion liquid 12 contained in the dispersion liquid storage section 14 is taken into the flow path of the flow path member 16 by the pressure of the pump 18, and is transported from one end of the flow path member 16 (i.e., the end on the dispersion liquid storage section 14 side) to the other end (i.e., the end on the dispersion liquid storage section 22 side).

[0039] Meanwhile, a magnetic field is generated from the magnetic pole surface 24 of the magnetic field generating unit 20, and the dispersion liquid 12 is exposed to the magnetic field at the passing portion 26 of the flow path member 16 arranged within the magnetic field region. This magnetic field causes the magnetic foreign matter powder contained in the dispersion liquid 12 to be captured on the inner surface of the flow path at the passing portion 26. The powder dispersion liquid 12 from which at least a portion of the magnetic foreign matter powder has been removed passes again through the passing portion 26 of the flow path member 16 arranged within the magnetic field region along the flow path, and after repeated removal of the magnetic foreign matter powder from the dispersion liquid 12 by capture, is stored in the dispersion liquid storage unit 22. The total exposure time, which is the total time that the dispersion liquid 12 is exposed to the magnetic field generated from the magnetic pole surface 24 of the magnetic field generating unit 20, is preferably 0.1 seconds or more, more preferably 0.2 seconds to 3 seconds, and even more preferably 0.3 seconds to 1 second, from the viewpoint of improving the removability of magnetic foreign matter powder.

[0040] The captured magnetic foreign powder can be easily collected by removing the flow path member 16 from the magnetic field region after the transportation of the dispersion liquid 12 is completed. Specifically, for example, a method can be used in which another fluid such as a liquid medium is caused to flow through the flow path to flush out the magnetic foreign powder captured on the inner surface of the flow path.

[0041] In this embodiment, magnetic foreign powder is removed by exposing the slurry dispersion liquid 12 to a magnetic field, so that the powder is less likely to aggregate and the magnetic foreign powder is more easily removed than when dry powder is directly exposed to a magnetic field.

[0042] The separation method of the present embodiment may further include a step of preparing the dispersion liquid 12. The dispersion liquid 12 is prepared, for example, by mixing a powder containing magnetic foreign matter powder with a liquid medium. In preparing the dispersion liquid 12, stirring may be performed with a stirring member as necessary. When the process includes a step of preparing the dispersion liquid 12, the time from the preparation of the dispersion liquid 12 to the first arrival of the dispersion liquid 12 at the passage portion 26 of the flow path member 16 (hereinafter also referred to as the "dispersion liquid storage time") is preferably 500 hours or less, more preferably 170 hours or less, even more preferably 24 hours or less, and particularly preferably 12 hours or less. By keeping the storage time of the dispersion within the above range, the removability of magnetic foreign matter powder is further improved. Although the reason for this is unclear, it is presumed that the short storage time of the dispersion prevents the agglomerates of powder particles from becoming stronger over time and becoming difficult to disintegrate.

[0043] The separation method of the present embodiment may further include a step of irradiating the dispersion liquid 12 with ultrasonic waves before passing through the magnetic field. When the separation device 10 has an ultrasonic irradiation unit, the ultrasonic irradiation unit may irradiate the dispersion liquid 12 with ultrasonic waves. Details of the ultrasonic irradiation unit and the step of irradiating ultrasonic waves are as described above.

[0044] (Application) The separating apparatus and separating method of the present disclosure are used for separating and removing magnetic foreign matter powder from a non-magnetic powder material containing magnetic foreign matter powder. Examples of non-magnetic powder materials containing magnetic foreign powder include ceramic powders used in ceramics for insulating substrates, non-conductive shields, heat dissipation insulators, abrasives, polishing agents, etc., resin-based powder materials, carbon materials, fibers, etc. More specifically, examples of the non-magnetic powder material containing magnetic foreign matter powder include inorganic particles used as an inorganic filler contained in a sealant that seals elements in electronic component devices, sealant particles manufactured using the inorganic particles, graphite particles used in manufacturing negative electrode materials for lithium ion secondary batteries, etc. Examples of the inorganic particles include silica particles, alumina particles, titania particles, glass particles, calcium carbonate particles, zirconium silicate particles, calcium silicate particles, silicon nitride particles, aluminum nitride particles, boron nitride particles, zirconia particles, etc.

[0045] Examples of magnetic foreign matter powders to be separated and removed include magnetic powders of steel, pure iron, iron oxide, stainless steel, nickel, cobalt, and the like. The magnetic foreign matter powder may have a small particle size. The smaller the particle size of the magnetic foreign matter powder to be separated and removed, the more difficult it is to be magnetically adsorbed. However, according to the above separation device and separation method, even if the particle size of the magnetic foreign matter powder is small, it can be adsorbed and separated and removed. The number-average particle size of the magnetic foreign matter powder can be, for example, 100 μm or less, and may be 75 μm or less. The number-average particle size of the magnetic foreign matter powder can be determined by measuring the collected magnetic foreign matter powder with a laser scattering diffraction method particle size distribution measuring device.

[0046] [Test example] The above embodiment will be specifically described below using test examples, but the scope of the above embodiment is not limited to these test examples.

[0047] <Test Example A> (Test Example A1) As the separation apparatus A, a separation apparatus 10 shown in FIG. A superconducting bulk magnet was used as the magnetic field generating unit 20. Excitation of the magnetic poles in the superconducting bulk magnet was performed by a field cooling method using a static magnetic field. Static magnetic field excitation was performed at 6 T using a superconducting solenoid magnet (JASTEC) with a maximum of 7.5 T. The cooling temperature of the bulk magnet was 4.0 K, and the magnetic field strength at the center of the magnetic pole surface 24 of the magnetic field generating unit 20 was 3.7 T. The excitation operation was repeated for each experiment, and after each experiment was completed, the magnetic field was turned off and the device was shut down. The magnetic pole surface 24 of the magnetic field generating unit 20 is flat and has a circular shape with a diameter of 6 cm.

[0048] A silicone rubber tube (outer diameter 6 mm, inner diameter 4 mm, total length 3 m) was used as the flow path member 16, and was arranged so that the dispersion liquid 12 passed through one magnetic field in a straight line 10 times, as shown in FIG. 2. Specifically, one layer of the flow path member 16 was arranged on the magnetic pole face 24 and the installation stand 28. The length of the straight region in one passing section 26 was 6 cm to 8 cm, and the length of each flow path between the passing sections was 10 cm to 20 cm. The cross-sectional area of ​​the flow path in the straight region of the passing section 26 was 12.56 mm 2 It was.

[0049] A mixture of 310 g of silica powder and 500 g of pure water, which was then suspended and stirred, was used as the dispersion 12. The viscosity of pure water at 25°C is 0.89 mPa·s. A constant volume liquid transfer pump (tube pump TP20SA, manufactured by ASONE) was used as the pump 18 , which is an example of a transport section, to take in the dispersion 12 into the flow path of the flow path member 16 and transport it from the dispersion storage section 14 to the dispersion storage section 22 . The flow rate of the dispersion 12 delivered by the pump 18 was 5.6 mL / s, the flow velocity was 44.6 cm / s, and the total exposure time in the dispersion 12 was 0.7 seconds.

[0050] 500 mL of dispersion liquid 12 stored in dispersion liquid storage section 22 was recovered, and the magnetic foreign matter powder was adsorbed and recovered by pouring it over the surface of a 1.5 T permanent magnet. After drying on a filter, the number of magnetic foreign matter powders that had passed through separation device A without being adsorbed by the magnetic field was determined by observing the number of particles using a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX).

[0051] A total of nine operations were performed to prepare a new dispersion 12, remove the magnetic foreign matter powder using separation device A, and determine the number of magnetic foreign matter powders remaining in the recovered dispersion 12. As a result, the total number of iron particles with a particle size (circle equivalent diameter) of 45 μm or more among the magnetic foreign matter particles that passed through separation device A without being magnetically adsorbed was zero over the nine operations, indicating that iron particles with a particle size of 45 μm or more could be completely removed.

[0052] (Comparative Test Example A2) As the separation device B, a device was used in which the arrangement of the flow path members in the magnetic field region was changed as shown in Fig. 3 compared to the separation device 10 shown in Fig. 1. Specifically, a flow path member 116 was used which had a spiral flow path and was arranged so that the dispersion liquid 12 passed through one magnetic field in a curved shape 10 times. A test was performed in the same manner as in Test Example A1, except that separation device B was used instead of separation device A. However, in the first four operations out of the seven operations, dispersion liquid 12 was transported from the inside to the outside of the spiral channel, and in the subsequent three operations, dispersion liquid 12 was transported from the outside to the inside of the spiral channel. As a result, among the magnetic foreign matter powders that passed through separation device B without being magnetically adsorbed, the number of iron powders with a particle size (equivalent circle diameter) of 45 μm or more was 3 in total in the first four operations, 3 in total in the subsequent three operations, and an average of 0.86 per operation in a total of seven operations.

[0053] The above results show that in Test Example A1, less magnetic foreign matter powder passed through the separation device without being magnetically attracted, and thus the magnetic foreign matter powder was more easily removed, compared to Comparative Test Example A2.

[0054] <Test Example B> (Test Example B1) The same separation operation as in Test Example A1 was carried out using the separation device A. Specifically, the dispersion liquid 12 was newly prepared, the magnetic foreign matter powder was removed using the separation device A, and the number of magnetic foreign matter powders remaining in the collected dispersion liquid 12 was determined. This operation was carried out three times in total. As a result, among the magnetic foreign matter powders that passed through separation device A without being magnetically adsorbed, the total number of iron powders having a particle size (circle equivalent diameter) of 45 μm or more was 0, and the average per operation was 0. Also, among the magnetic foreign matter powders that passed through separation device A without being magnetically adsorbed, the total number of stainless steel (SUS) powders having a particle size (circle equivalent diameter) of 45 μm or more was 0, and the average per operation was 0.

[0055] (Test Example B2) The flow path member 16 of the separation device A was flattened using a jig to change the maximum height of the cross section of the flow path in the direction of the magnetic field from 4 mm to 2 mm, and this was used as the separation device C. The cross-sectional area of ​​the flow path in the flattened flow path member 16 was 9 mm 2 It was. A test was performed in the same manner as in Test Example B1, except that the separation device C was used instead of the separation device A. Specifically, the procedure of newly preparing the dispersion liquid 12, removing the magnetic foreign matter powder using the separation device C, and determining the number of magnetic foreign matter powders remaining in the recovered dispersion liquid 12 was performed three times in total. As a result, among the magnetic foreign matter powders that passed through separation device C without being magnetically adsorbed, the total number of iron powders having a particle size (circle equivalent diameter) of 45 μm or more was 0, and the average per operation was 0. Also, among the magnetic foreign matter powders that passed through separation device C without being magnetically adsorbed, the total number of stainless steel (SUS) powders having a particle size (circle equivalent diameter) of 45 μm or more was 0, and the average per operation was 0.

[0056] (Test Example B3) The flow path member 16 of the separation device A was flattened by a jig to change the maximum height of the cross section of the flow path in the direction of the magnetic field from 4 mm to 1 mm, and this was used as the separation device D. The cross-sectional area of ​​the flow path in the flattened flow path member 16 was 5 mm 2 It was. A test was performed in the same manner as in Test Example B1, except that Separator D was used instead of Separator A. Specifically, a new dispersion 12 was prepared, magnetic foreign matter powder was removed using Separator D, and the number of magnetic foreign matter powders remaining in the collected dispersion 12 was determined. This operation was performed three times in total. As a result, among the magnetic foreign matter powders that passed through separation device D without being magnetically adsorbed, the number of iron powders with a particle size (circle equivalent diameter) of 45 μm or more was 1 in total, with an average of 0.33 per operation. Also, among the magnetic foreign matter powders that passed through separation device D without being magnetically adsorbed, the number of stainless steel (SUS) powders with a particle size (circle equivalent diameter) of 45 μm or more was 4 in total, with an average of 1.33 per separation operation.

[0057] From the above results, it can be seen that in all of Test Examples B1 to B3, the number of iron powders that passed through the separator without being magnetically attracted by the separator was small, and the removability was high. Among them, Test Examples B1 and B2 in particular showed high removability, as compared to Test Example B3, with respect to not only iron powders but also stainless steel (SUS) powders, but also the number of iron powders that passed through the separator without being magnetically attracted by the separator was small. In addition, in test example B3, the reason why the number of stainless steel (SUS) powder particles that passed through the separation device without being magnetically adsorbed was greater than the number of iron powder particles is presumably because the magnetization of stainless steel (SUS) powder particles is weaker than the magnetization of iron powder particles.

[0058] <Test Example C> (Test Examples C1 to C3) As the separation apparatus E, an apparatus in which an ultrasonic irradiation unit was added to the separation apparatus A was used. As an ultrasonic generator in the ultrasonic irradiation section, a tabletop ultrasonic cleaner (manufactured by Aiwa Medical Industry Co., Ltd., product name: AU-16C, frequency: 28 kHz, oscillation output: 75 W) was used. As in Test Examples A and B, 310 g of silica powder and 500 g of pure water were mixed, suspended, and stirred to prepare dispersion 12. The obtained dispersion 12 was stored at 25° C. as necessary, and then irradiated with ultrasonic waves for 10 minutes in the ultrasonic irradiation section of separation device E. Thereafter, the dispersion 12 irradiated with ultrasonic waves was immediately (within 30 minutes) stored in dispersion storage section 14.

[0059] A test was performed in the same manner as in Test Example B1, except that separation apparatus E was used instead of separation apparatus A, and ultrasonic irradiation was performed in the ultrasonic irradiation unit of separation apparatus E. Specifically, dispersion liquid 12 was newly prepared, and the operation of irradiating ultrasonic waves and removing magnetic foreign matter powder using separation apparatus E, and determining the number of magnetic foreign matter powders remaining in the recovered dispersion liquid 12 was performed three times in total. Table 1 shows the time (dispersion storage time) from preparation of dispersion 12 to the first arrival of dispersion 12 at passage portion 26 of flow path member 16 in each of Test Examples C1 to C3. In each operation, the total number of iron powder particles having a particle size (circle equivalent diameter) of 10 μm or more and the total number of stainless steel (SUS) powder particles having a particle size (circle equivalent diameter) of 10 μm or more were confirmed among the magnetic foreign matter powder particles that passed through the separation device E without being magnetically adsorbed. The average value of the total numbers in three operations ("average number of foreign matter particles" in the table) is shown in Table 1.

[0060] (Test Examples C4~C6) Tests were carried out in the same manner as in Test Examples C1 to C3, except that the separating apparatus A was used instead of the separating apparatus E and ultrasonic irradiation was not performed. Table 1 shows the time (dispersion storage time) from preparation of dispersion 12 to the first arrival of dispersion 12 at passage portion 26 of flow path member 16 in each of Test Examples C4 to C6. In each operation, the total number of iron powder particles having a particle size (circle equivalent diameter) of 10 μm or more and the total number of stainless steel (SUS) powder particles having a particle size (circle equivalent diameter) of 10 μm or more were confirmed among the magnetic foreign matter powder particles that passed through the separation device A without being magnetically adsorbed. The average value of the total numbers in three operations ("average number of foreign matter particles" in the table) is shown in Table 1.

[0061] [Table 1]

[0062] From the above results, it is understood that the separator E equipped with the ultrasonic irradiation unit has an even higher ability to remove magnetic foreign matter powder with a particle size (circle equivalent diameter) of 10 μm or more. It is also clear that the shorter the storage time of the dispersion liquid, the higher the removability of magnetic foreign matter powder with a particle size (equivalent circle diameter) of 10 μm or more. [Explanation of symbols]

[0063] 10 Separation device 12 Dispersion 14 Dispersion liquid storage section 16 Flow path components 18 Pump (an example of a transport section) 20 Magnetic field generating unit 22 Dispersion liquid storage section 24 Magnetic pole face 26 Passage section 28 Installation stand 30 Stirring member 116 Flow path components 124 Magnetic pole face

Claims

1. A magnetic field generating unit that generates a magnetic field, the magnetic field generating unit including at least one magnet selected from the group consisting of a superconducting bulk magnet and a superconducting solenoid magnet; a flow path member having a tubular flow path through which a dispersion liquid in which a powder containing magnetic foreign matter powder is dispersed in a liquid medium flows, the flow path being arranged so that the dispersion liquid passes through the magnetic field in a straight line a plurality of times; A magnetic foreign matter powder separation device having the above structure.

2. 2. The magnetic foreign matter powder separation device according to claim 1, wherein a maximum height in the direction of the magnetic field in a cross section perpendicular to the flow direction of the dispersion liquid in the flow path is 1.2 mm to 10 mm.

3. 3. The magnetic foreign matter powder separation device according to claim 1, further comprising an ultrasonic irradiation unit that irradiates the dispersion liquid with ultrasonic waves before the dispersion liquid passes through the magnetic field.

4. generating a magnetic field from a magnetic field generating unit including at least one magnet selected from the group consisting of a superconducting bulk magnet and a superconducting solenoid magnet; A dispersion liquid in which a powder containing magnetic foreign matter powder is dispersed in a liquid medium is passed through a tubular flow path arranged so that the dispersion liquid passes through the magnetic field in a straight line a plurality of times; The magnetic foreign matter powder separation method includes the steps of:

5. 5. The magnetic foreign matter powder separation method according to claim 4, wherein a maximum height in the direction of the magnetic field in a cross section perpendicular to a flow direction of the dispersion liquid in the flow channel is 1.2 mm to 10 mm.

6. 6. The method for separating magnetic foreign matter powder according to claim 4 or 5, wherein the flow rate of the dispersion liquid is 100 cm / s or less.

7. 6. The method for separating magnetic foreign matter powder according to claim 4, further comprising irradiating the dispersion with ultrasonic waves before the dispersion passes through the magnetic field.

8. The method further comprises dispersing the powder in the liquid medium to prepare the dispersion; 6. The method for separating magnetic foreign matter powder according to claim 4, wherein the time from preparation of the dispersion to the first exposure of the dispersion to the magnetic field is 500 hours or less.

9. The method further comprises dispersing the powder in the liquid medium to prepare the dispersion; 8. The method for separating magnetic foreign matter powder according to claim 7, wherein the time from preparation of the dispersion to the first exposure of the dispersion to the magnetic field is 500 hours or less.

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