JP6344550B2 - Ferrite particles for transporting functional powder - Google Patents

Description

  The present invention relates to a ferrite particle that is mixed with a functional powder for the purpose of improving the handleability of the functional powder when the functional powder is used for transportation, conveyance, molding, and the like.

  At present, functional powders such as toners used in printers and copiers are used in various fields and applications, and electrophotographic development methods are used.

  The developing method based on this electrophotographic developing method is a method in which toner particles in a developer are attached to an electrostatic latent image formed on a photoreceptor and developed, and the developer used in this method is toner particles. And a two-component developer composed of carrier particles and a one-component developer using only toner particles.

  Among these developers, as a developing method using a two-component developer composed of toner particles and carrier particles, the cascade method has been used in the past, but at present, the magnetic brush method using a magnet roll is the mainstream. It is.

  In the two-component developer, the carrier particles are agitated together with the toner particles in the developing box filled with the developer, thereby imparting a desired charge to the toner particles, and thus being charged. A carrier material for transporting toner particles to the surface of the photoreceptor to form a toner image on the photoreceptor. The carrier particles remaining on the developing roll holding the magnet are returned to the developing box from the developing roll, mixed and stirred with new toner particles, and used repeatedly for a certain period.

  Unlike the one-component developer, the two-component developer has the function of mixing and stirring the carrier particles with the toner particles, charging the toner particles, and further transporting the toner particles. Good controllability. Therefore, the two-component developer is suitable for a full-color developing device that requires high image quality and a device that performs high-speed printing that requires image maintenance reliability and durability.

  On the other hand, in the field of using functional powders other than the electrophotographic development system, the functional powder is often handled as a single unit, but the functional powder used tries to express its own functionality. Then, there is a thing with inferior handling property.

  For example, functional powders that are easily altered by moisture and oxygen in the air, functional powders that have extremely poor flowability because they are not isotropic, functional powders that have extremely low bulk density, and radioactive materials. Therefore, handling is difficult, such as when it is harmful to the human body and cannot be handled directly, and there may be significant restrictions on environmental conditions, equipment conditions, etc. during use.

Patent Document 1 (Japanese Patent Laid-Open No. 08-22150) describes a ferrite carrier for an electrophotographic developer in which a part of ferrite composed of MnO, MgO and Fe ₂ O ₃ is substituted with SrO. The ferrite described in this document can obtain an electrophotographic developer carrier that is excellent in image quality and durability, is environmentally friendly, has a long life, and is excellent in environmental stability by reducing the variation in magnetization between ferrite carrier particles. It is supposed to be possible.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2009-244573) uses as a toner powder any one of a metal powder, an inorganic compound, or a mixed powder thereof as a toner powder for circuit formation, and uses the toner powder for circuit formation as a carrier. Carrier particles that are attached to the surface of the particles with an electrostatic force and are carried to the surface of the insulating layer to form a circuit shape directly on the insulating layer. The carrier particles are formed on the surface of the carrier core particles. There is described a carrier particle for forming a wiring circuit by an electrophotographic developing method having a certain amount of a coating layer using an acrylic resin composition and having a carrier core material particle having a shape factor SF-1 of 100 to 110.

  Further, in Patent Document 3 (Japanese Patent Laid-Open No. 2006-235460), the particle shape is indefinite, and 40% by number or more is a rock-type rock sugar shape and / or oyster shell shape particle, and the shape factor (SF− 1) is 140 to 250, and an irregular ferrite carrier having a distribution width (δ) of 60 or less is described.

Japanese Patent Application Laid-Open No. 08-22150 JP 2009-244573 A JP 2006-235460 A

  However, the ferrite particles used in Patent Documents 1 to 3 pay attention to the magnetic characteristics and physical characteristics, and do not indirectly improve the handleability with the functional powder.

  Thus, there have not been many proposals for ferrite particles that indirectly improve handling by using the magnetic properties and physical properties of the ferrite particles by mixing the ferrite particles with the functional powder as a medium.

  Therefore, the object of the present invention is to transport the functional powder indirectly by using the magnetic and physical properties of the ferrite particles by mixing the ferrite particles as a medium with the functional powder. It is to provide ferrite particles for use.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have achieved the above object by providing ferrite particles having a specific composition and having an average particle diameter of the ferrite particles within a certain range. It has been found that this is possible, and the present invention has been achieved.

That is, in the present invention, the composition of the ferrite particles is represented by the following formula (1), the average particle diameter of the ferrite particles is 200 to 3000 μm, and the peak pore diameter of the ferrite particles measured by a mercury porosimeter is 10 to 10 μm. The present invention provides a ferrite particle for transporting a functional powder characterized by being 200 μm .

  The ferrite particles according to the present invention are represented by the formula (1), and a part of (MnO) and / or (MgO) in the formula (1) is substituted with SrO. 1-10 mol% is desirable.

  The ferrite particles according to the present invention preferably have an angle of repose of 10 to 20 °.

The ferrite particles according to the present invention preferably have a ferrite particle magnetization of 35 to 85 Am ² / kg when 3K · 1000 / 4π · A / m is applied.

  The present invention also provides resin-coated ferrite particles in which the surface of the ferrite particles is coated with a resin.

  The present invention also provides a mixture comprising the ferrite particles or the resin-coated ferrite particles and a functional powder.

  In the above mixture according to the present invention, the functional powder preferably has an average particle size of 15 to 1000 μm.

  Moreover, the transport method according to the present invention provides a powder transport method characterized by using the above mixture.

  In the method for transporting powder according to the present invention, it is desirable to remove ferrite particles from the mixture and to use the removed ferrite particles again mixed with functional powder.

  The present invention also provides a powder holding method characterized by utilizing the magnetic properties and / or powder properties using the ferrite particles or the resin-coated ferrite particles.

The ferrite particles for transporting functional powder according to the present invention are ferrite particles having a specific composition, and the ferrite particles have an average particle size of 200 to 3000 μm, and the ferrite particles have a peak fineness measured by a mercury porosimeter. Since the pore diameter is 10 to 200 μm, by mixing the ferrite particles with the functional powder as a medium, the handling properties are indirectly improved by using the magnetic properties and physical properties of the ferrite particles. .

1 is a scanning electron micrograph (× 35) of the ferrite particles obtained in Example 6. FIG.

Hereinafter, modes for carrying out the present invention will be described.
<Functional powder transport ferrite particles and resin-coated ferrite particles according to the present invention>

  The ferrite particles in the present invention are represented by the following formula (1) as a general formula.

  Here, when the composition is such that x is less than 35 mol% and y exceeds 15 mol%, the magnetization of the ferrite cannot be increased, and it becomes difficult to control the mixture by a magnetic field, which is not preferable. Further, when x exceeds 45 mol% and y is less than 5 mol%, the magnetization can be increased, but heat is not sufficiently transferred to the inside of the ferrite particles during the main firing, and the magnetic force of one particle is greatly different. Since possibility is high, it is not preferable. By containing Mn in the above range, the magnetization on the low magnetic field side can be increased, and the effect of preventing reoxidation upon exiting from the furnace in the main firing can be expected.

In order to obtain desired magnetic characteristics and to obtain ferrite having stable characteristics over time, z = 40 mol% or more is preferable. In this case, although depending on the amounts of MnO and MgO, the weight ratio of Fe ₂ O ₃ is 50% by weight or more.

  The ferrite particles according to the present invention are represented by the formula (1), and a part of (MnO) and / or (MgO) in the formula (1) is substituted with SrO, and the substitution amount of the SrO is 0.1. It is desirable that it is 10 mol%. SrO not only contributes to the adjustment of resistance and surface properties, but also contains the effect of increasing the charging ability of the ferrite particles. Moreover, when mixing and using with functional powder, a magnetic field is applied with respect to a mixture, and when a magnetic field is removed after that, a mixture can make it hard to lose a shape with the coercive force.

  If the amount of substitution of SrO is less than 0.1 mol%, it is difficult to obtain the effect of containing SrO as described above, such being undesirable. If the substitution amount of SrO exceeds 10 mol%, the residual magnetization and coercive force are increased, and the fluidity of the ferrite particles is deteriorated, so that the miscibility with the functional powder is deteriorated. The amount of SrO is preferably from 0.1 to 5 mol%, more preferably from 0.3 to 2.5 mol%.

(Contents of Fe, Mn, Mg and Sr)
The contents of these Fe, Mn, Mg and Sr are measured by the following.
0.2 g of ferrite particles are weighed, 60 ml of pure water added with 20 ml of 1N hydrochloric acid and 20 ml of 1N nitric acid is heated to prepare an aqueous solution in which ferrite particles are completely dissolved, and an ICP analyzer (ICPS manufactured by Shimadzu Corporation) is prepared. -1000IV) was used to measure the contents of Fe, Mn, Mg and Sr.

  In the ferrite particles according to the present invention, the average particle size needs to be 200 to 3000 μm. Due to the average particle size of the ferrite particles being in this range, when mixed and / or separated from the functional powder, it is indirectly excellent in handling properties by using the magnetic properties and physical properties of the ferrite particles. Can be. This average particle diameter is determined by the following equivalent circle diameter.

  If the average particle size of the ferrite particles is less than 200 μm, when the functional powder is separated by applying a magnetic field, the ferrite particles may be aggregated and cannot be separated from the functional powder. Further, when the average particle diameter of the ferrite particles exceeds 3000 μm, the gap between the ferrite particles becomes too large, and the functionality when the mixture of the functional powder and the ferrite particles is conveyed by the magnetic field in a state where a magnetic field is applied. There is a possibility that the powder will be detached and sufficient transportability of the functional powder cannot be secured.

  In the ferrite particles according to the present invention, it is desirable that the peak pore diameter of the ferrite particles measured by a mercury porosimeter is 10 to 200 μm.

  When the peak pore diameter of the ferrite particles exceeds 200 μm, when the magnetic field is applied to control the fluidity, moldability, and transportability of the mixture of the ferrite particles and the functional powder, the functional powder is controlled by the ferrite particles. There is a possibility that handling cannot be sufficiently performed and handling properties are deteriorated. On the other hand, the average pore diameter of the ferrite particles according to the present invention does not make the peak pore diameter less than 10 μm.

(Pore volume and peak pore diameter of ferrite particles)
Measurement of the pore volume of the ferrite particles is performed as follows. That is, it measured using mercury porosimeter Pascal140 and Pascal240 (ThermoFisher Scientific company make). CD3P (for powder) was used as the dilatometer, and the sample was put in a commercially available gelatin capsule having a plurality of holes and placed in the dilatometer. After degassing with Pascal 140, mercury was filled and the low pressure region (0 to 400 Kpa) was measured to determine the pore volume of the ferrite particles. In addition, when the pore diameter is obtained, the control / analysis combined use software PASCAL 140/240/440 attached to the apparatus is used, the peak pore diameter on the low pressure side is defined as the pore diameter, the surface tension of mercury is 480 dyn / cm, and the contact angle is 141. Calculated as 3 °.

  The ferrite particles according to the present invention preferably have a shape factor SF-2 of 100 to 180. The shape factor SF-2 is 100 in the case of a perfect sphere, so it does not become less than 100. When the shape factor SF-2 exceeds 180, the particle shape tends to be deteriorated, which causes the fluidity of the mixture of ferrite particles and functional powder to deteriorate, which is not preferable.

(Shape factor SF-2)
The shape factor SF-2 (roundness) is a numerical value obtained by dividing the value obtained by squaring the projected circumference of the ferrite particles by the value obtained by dividing the value by the projected area of the ferrite particles by 4π, and further multiplying by 100. The closer the carrier shape is to a sphere, the closer to 100. The shape factor SF-2 (roundness) is measured as follows. The shape factor SF-2 was calculated for each particle, and the average value of 100 particles was defined as the ferrite particle shape factor SF-2.

  The shape factor SF-2 of this particle was obtained by photographing a ferrite particle using FE-SEM (SU-8020 manufactured by Hitachi High-Technologies Corporation) in the LM (L) mode, an acceleration voltage of 1 KV, and a field of magnification of 35 times. The information is introduced into image analysis software (Image-Pro PLUS) manufactured by Media Cybernetics through an interface and analyzed to obtain a (projection) perimeter for each particle, which is a value obtained from the following equation.

(Average particle size)
The equivalent circle diameter was calculated for each particle from the (projected) area of the ferrite particles obtained above, and the average value of 100 particles was defined as the average particle diameter.

The ferrite particles according to the present invention preferably have a magnetization of 35 to 85 Am ² / kg when 3K · 1000 / 4π · A / m is applied.

If the magnetization of the ferrite particles is less than 35 Am ² / kg when 3K · 1000 / 4π · A / m is applied, the ferrite particles cannot be aligned along the lines of magnetic force and it is difficult to transport the functional powder. Become. On the other hand, the composition described in this patent does not exceed 85 Am ² / kg.

(Magnetic properties)
This magnetization was measured using an integral BH tracer BHU-60 type (manufactured by Riken Denshi Co., Ltd.). A magnetic field measuring H coil and a magnetization measuring 4πI coil are placed between the electromagnets. In this case, the sample is placed in a 4πI coil. The outputs of the H coil and the 4πI coil whose magnetic field H is changed by changing the current of the electromagnet are respectively integrated, and the H output is drawn on the X axis, the output of the 4πI coil is drawn on the Y axis, and a hysteresis loop is drawn on the recording paper. As measurement conditions, sample filling amount: about 1 g, sample filling cell: inner diameter 7 mmφ ± 0.02 mm, height 10 mm ± 0.1 mm, 4πI coil: measured with 30 turns.

  The ferrite particles according to the present invention preferably have an angle of repose of 15 to 25 °.

  When the repose angle of the ferrite particles is larger than 25 °, it indicates that the fluidity is not good, and sufficient transportability may not be obtained when mixed with functional powder. Further, if the repose angle of the ferrite particles is smaller than 15 °, it indicates that the fluidity is too high, and the mixing amount of the ferrite particles for conveying the functional powder increases, and the conveyance efficiency may deteriorate.

  The ferrite particles according to the present invention desirably have a collapse angle of 10 to 20 °.

  If the decay angle of the ferrite particles is larger than 20 °, it indicates that the fluidity is not good, and sufficient transportability may not be obtained when mixed with the functional powder. Further, when the decay angle of the ferrite particles is smaller than 10 °, it indicates that the fluidity is too high, and the amount of the ferrite particles for conveying the functional powder when used by mixing with the functional powder. May increase and the conveyance efficiency may deteriorate.

(Repose angle and collapse angle)
These repose angles and collapse angles were measured according to JIS 9301-2-2.

  The ferrite particles for transporting the functional powder according to the present invention are coated with a coating resin on the surface of the ferrite particles in order to improve further handling properties at the time of mixing, transporting and molding with the functional powder. It is desirable to use it as ferrite particles. By performing surface coating suitable for the functional powder, desired powder characteristics can be obtained.

  The coating resin is not particularly limited. For example, fluorine resin, acrylic resin, epoxy resin, polyamide resin, polyamideimide resin, polyester resin, unsaturated polyester resin, urea resin, melamine resin, alkyd resin, phenol resin, fluorine acrylic resin, acrylic-styrene resin, silicone resin, Alternatively, modified silicone resins modified with resins such as acrylic resin, polyester resin, epoxy resin, polyamide resin, polyamideimide resin, alkyd resin, urethane resin, and fluororesin can be used. In view of the detachment of the resin due to mechanical stress during use, a thermosetting resin is preferably used. Specific examples of thermosetting resins include epoxy resins, phenol resins, silicone resins, unsaturated polyester resins, urea resins, melamine resins, alkyd resins, and resins containing them. The coating amount of the resin is preferably 0.5 to 5.0 parts by weight with respect to 100 parts by weight of the ferrite particles.

  In addition, the coating resin can contain a charge control agent. Examples of the charge control agent include various charge control agents generally used for toners and various silane coupling agents. This is because, when a large amount of resin is coated, the charge imparting ability may be reduced, but it can be controlled by adding various charge control agents and silane coupling agents. The types of charge control agents and coupling agents that can be used are not particularly limited, but charge control agents such as nigrosine dyes, quaternary ammonium salts, organometallic complexes, and metal-containing monoazo dyes, aminosilane coupling agents, and fluorine-based silane couplings. An agent or the like is preferable.

<Method for Producing Ferrite Particles for Transporting Functional Powder According to the Present Invention>
A method for producing ferrite particles for transporting functional powder according to the present invention will be described.

  In the method for producing ferrite particles for transporting functional powder according to the present invention, first, an appropriate amount of raw materials is weighed, and then pulverized and mixed in a ball mill or vibration mill for 0.5 hours or more, preferably 1 to 20 hours. The raw material is not particularly limited, but is preferably selected so as to have a composition containing the above-described elements.

  The pulverized product thus obtained is pelletized using a pressure molding machine or the like and then calcined at 700 to 1300 ° C. You may grind | pulverize without using a pressure molding machine, add water to make a slurry, and granulate using a spray dryer. After calcination, the mixture is further pulverized with a ball mill or a vibration mill, and then a binder is added and granulated using a dry mixing apparatus such as a Henschel mixer.

  Thereafter, the obtained granulated material is subjected to a binder removal treatment, and then held at 800 to 1500 ° C. for 1 to 24 hours in an atmosphere in which the oxygen concentration is controlled to perform main baking. At that time, a rotary electric furnace, a batch electric furnace or a continuous electric furnace is used, and an atmosphere at the time of firing is also injected with an inert gas such as nitrogen or a reducing gas such as hydrogen or carbon monoxide. The concentration may be controlled.

  The fired product thus obtained is classified. As a classification method, the particle size is adjusted to a desired particle size using an existing air classification, mesh filtration method, sedimentation method, classification using various sieves, or the like.

  As described above, after producing the ferrite particles, the surface may be covered with a resin. In particular, the powder characteristics are often influenced by the materials and properties existing on the surface of the ferrite particles. Therefore, the desired powder characteristics can be adjusted by coating the surface with an appropriate resin. As a coating method, the coating can be performed by a known method such as a brush coating method, a dry method, a spray drying method using a fluidized bed, a rotary drying method, an immersion drying method using a universal stirrer, or the like. In order to improve the coverage, a fluidized bed method is preferred. In the case of baking after resin coating, either an external heating method or an internal heating method may be used. For example, a stationary or fluid electric furnace, a rotary electric furnace, a burner furnace, or microwave baking may be used. When a UV curable resin is used, a UV heater is used. Although the baking temperature varies depending on the resin to be used, a temperature equal to or higher than the melting point or the glass transition point is necessary. For a thermosetting resin or a condensation-crosslinking resin, it is necessary to raise the temperature to a point where the curing proceeds sufficiently.

  The mixture according to the present invention comprises the ferrite particles or resin ferrite particles obtained by coating the ferrite particles with a resin and functional powder.

  Examples of functional powders include various metal powders, various inorganic compound powders (hydroxides, carbonates, metal oxides, sulfides, nitrides, etc.), resin powders, or mixed powders thereof. It is used in applications such as developer toner, circuit forming toner, 3D printer powder (raw material powder), powder coating powder, and the like.

  The average particle size of the functional powder is desirably 15 to 1000 μm. If the average particle size of the functional powder is less than 15 μm, the particle size is too small, and a large amount of the functional powder is efficiently conveyed over a large area. If it exceeds 1000 μm, the particle size is too large, and it is difficult to adapt to a system that conveys a mixture of ferrite particles and functional powder by a magnetic field.

  The powder transport method according to the present invention is characterized by using the above-mentioned mixture. Desirably, the ferrite particles are removed from the mixture, and the removed ferrite particles are mixed with the functionality again and used.

  The powder holding method according to the present invention is characterized by utilizing magnetic properties and / or powder properties using ferrite particles or resin-coated ferrite particles.

  Hereinafter, the present invention will be specifically described based on examples and the like.

[Example 1]
As raw materials, Fe ₂ O ₃ : 51 mol%, Mn ₃ O ₄ : 13 mol%, Mg (OH) ₂ : 9 mol% and SrCO ₃ : 1 mol% were charged, and pulverized and mixed for 1 hour with a Henschel mixer. The pulverized material thus obtained was pelletized using a roller compactor, and then pre-baked using a rotary kiln at 1000 ° C. for 5 hours in the air.

  After calcination, it was further pulverized by a ball mill. The average particle size of the pulverized product was 3.54 μm. 500 g of polyvinyl alcohol (10% by weight aqueous solution) was added to 3 kg of the calcined powder, and mixed and granulated using a Henschel mixer for 15 minutes.

  Thereafter, the obtained granulated material is subjected to a binder removal treatment at 900 ° C. to remove organic substances, and then held in an electric furnace at 1280 ° C. for 4 hours in an atmosphere having an oxygen concentration of 0% by volume, followed by firing. Went. Thereafter, the fired product was crushed, further classified to adjust the particle size, and the low-magnetism product was separated by magnetic separation to obtain ferrite particles.

[Example 2]
Ferrite particles were obtained in the same manner as in Example 1 except that the temperature of the main firing was 1300 ° C.

[Example 3]
Ferrite particles were obtained in the same manner as in Example 1 except that the main firing temperature was 1180 ° C.

[Example 4]
Ferrite particles were obtained in the same manner as in Example 1 except that the atmosphere during the main firing was in the air.

[Example 5]
Ferrite particles were obtained in the same manner as in Example 1 except that the classification conditions were changed.

[Example 6]
Ferrite particles were obtained in the same manner as in Example 1 except that the classification conditions were changed.

[Example 7]
Ferrite particles were obtained in the same manner as in Example 1, except that Fe ₂ O ₃ : 50 mol%, Mn ₃ O ₄ : 11.7 mol% and Mg (OH) ₂ : 15 mol% were charged as raw materials. It was.

[Example 8]
Ferrite particles were obtained in the same manner as in Example 1 except that Fe ₂ O ₃ : 50 mol%, Mn ₃ O ₄ : 15 mol% and Mg (OH) ₂ : 5.1 mol% were charged as raw materials. It was.

[Example 9]
As raw materials, Fe ₂ O ₃ : 60 mol%, Mn ₃ O ₄ : 11.7 mol%, Mg (OH) ₂ : 5 mol% and SrCO ₃ : 2 mol% were charged, and the main calcination was performed in the atmosphere. Except for the above, ferrite particles were obtained in the same manner as in Example 1.

[Example 10]
Ferrite particles were obtained in the same manner as in Example 1 except that Fe ₂ O ₃ : 40 mol%, Mn ₃ O ₄ : 15 mol% and Mg (OH) ₂ : 15 mol% were charged as raw materials.

[Example 11]
Ferrite particles were obtained in the same manner as in Example 1, except that Fe ₂ O ₃ : 51 mol%, Mn ₃ O ₄ : 13 mol% and Mg (OH) ₂ : 9 mol% were charged as raw materials.

[Example 12]
Fe ₂ O ₃ : 51 mol%, Mn ₃ O ₄ : 13 mol%, Mg (OH) ₂ : 9 mol% and SrCO ₃ : 2 mol% were charged as raw materials, and the main firing was performed in the air. Obtained ferrite particles in the same manner as in Example 1.

[Example 13]
The ferrite particles obtained in Example 1 were subjected to a resin coating treatment with an all-purpose mixing stirrer using an acrylic resin (LR-269 manufactured by Mitsubishi Rayon) so that the ferrite particles would be 0.25% by weight. The resin solution used was diluted with toluene so that the resin solid content was 20% by weight. After resin coating, baking was performed at 150 ° C. for 2 hours in a hot air dryer to obtain resin-coated ferrite particles.

[Comparative Example 1]
Example except that the calcined powder was pulverized and granulated with a wet bead mill and a spray dryer, and 2000 g of polyvinyl alcohol (10% by weight aqueous solution) was added to 20 kg of the calcined powder, and then the binder was removed at 650 ° C. In the same manner as in Example 1, ferrite particles were obtained. The solid content in the slurry after pulverization was 50% by weight.

[Comparative Example 2]
Ferrite particles were obtained in the same manner as in Comparative Example 1 except that the binder was removed at 1050 ° C. and the main firing was performed by thermal spraying.

[Comparative Example 3]
Example 1 except that the average particle size of the pulverized product further pulverized by a ball mill after pre-baking was 105.87 μm, polyvinyl alcohol was not added, pulverization was performed with a roll crusher, and no debinding treatment was performed. Similarly, ferrite particles were obtained.

  Production conditions of Examples 1 to 13 and Comparative Examples 1 to 3 [raw material charging, molding apparatus, calcining conditions (calcining temperature and calcining atmosphere), average particle size after pulverization, main granulation conditions (weight after calcining) , Solid content, PVA amount, granulator / pulverizer and mixing time), binder removal treatment, main firing conditions (firing temperature), firing atmosphere] are shown in Tables 1 and 2. Moreover, the scanning electron micrograph (x35) of the ferrite particle obtained by Example 6 is shown in FIG. Also, the composition, powder characteristics (average particle diameter, tap density, peak pore diameter, angle of repose and decay angle) of the ferrite particles obtained in Examples 1-12 and Comparative Examples 1-3, shape Table 3 shows the coefficient (SF-2) and magnetic characteristics (magnetization, coercive force, and remanent magnetization). The method for measuring the tap density in Table 3 is shown below. Other measurement methods are as described above. Table 4 shows the evaluation of holdability, transportability, and separability.

(Tap density)
This was performed according to JIS Z 2512-2012.

(Evaluation of holdability, transportability and separability)
19.4 g of the obtained ferrite particles and 0.6 g of functional powder (Glass Bubbles iM16K manufactured by 3M) were put in a 50 cc glass bottle and mixed for 30 minutes in a ball mill with a rotation speed of 100 rpm.

(Holding property)
The Nd-Fe-B magnet is brought close to the bottom of the glass bottle containing the obtained mixture, and the glass bottle is turned upside down with the mixture agglomerated in the glass bottle, and the functional powder detached on the glass bottle lid is recovered. The weight was measured (the smaller the weight of the recovered functional powder, the better the holdability).

(Transportability)
Move the Nd-Fe-B magnet close to the side of the glass bottle containing the resulting mixture, slowly roll it over, rotate it in the same direction 10 times by hand, and then make the mouth face down, The functional powder detached from the lid was collected and its weight was measured (the smaller the weight of the collected functional powder, the better the transportability).

(Separability)
Invert the glass bottle containing the resulting mixture, bring the Nd-Fe-B magnet closer from the upper side of the glass bottle so that the mixture aggregates on the bottom of the glass bottle, and collect the functional powder detached on the lid of the glass bottle. The weight was measured (the greater the weight of the recovered functional powder, the better the separation).

The evaluation criteria for holdability, transportability and separation in Table 4 are as follows.
◎: Excellent 〇: Good △: Acceptable ×: Impossible

  As is clear from the results of Table 4, Examples 1 to 13 are good in all of the holdability, transportability, and separation property of the functional powder. In particular, Example 13 is holdability, and Example 6 is The transportability of Example 5 was excellent in separability. As shown in FIG. 1, the particle shape was a granular particle in which a smooth surface state different from that of Patent Document 3 was formed. On the other hand, in Comparative Example 1, since the ferrite particles were small in size, they easily aggregated, resulting in poor holdability and separability. Comparative Example 2 had good transportability because of its round particle shape, but it was easy to agglomerate, resulting in poor holdability and separability. Comparative Example 3 had an indeterminate shape and had good holdability, but resulted in poor transportability and separation.

  By mixing the ferrite particles for transporting the functional powder according to the present invention into the functional powder as a medium, the handling properties are indirectly improved using the magnetic properties and physical properties of the ferrite particles. Become.

Claims (8)

The composition of the ferrite particles is represented by the following formula (1), the average particle diameter of the ferrite particles is 200 to 3000 μm, and the peak pore diameter of the ferrite particles measured by a mercury porosimeter is 10 to 200 μm. Ferrite particles for functional powder transport.
  The function according to claim 1, wherein a part of (MnO) and / or (MgO) in the formula (1) is substituted with SrO, and the substitution amount of SrO is 0.1 to 10 mol%. Ferrite particles for transporting porous powder.   Resin-coated ferrite particles for transporting functional powder obtained by coating the surface of the ferrite particles according to claim 1 or 2 with a resin.   A mixture comprising the ferrite particles or resin-coated ferrite particles according to any one of claims 1 to 3 and a functional powder.   The mixture according to claim 4, wherein the functional powder has an average particle size of 15 to 1000 μm. A powder transportation method using the mixture according to claim 4 or 5.   The powder transport method according to claim 6, wherein ferrite particles are removed from the mixture, and the removed ferrite particles are mixed with a functional powder again and used.   A powder holding method using magnetic properties and / or powder properties using the ferrite particles or resin-coated ferrite particles according to claim 1.