Zinc oxide particles, method for producing zinc oxide particles, and resin composition

Abstract

A zinc oxide particle which is a polyhedral zinc oxide particle, and a microcrystal diameter of a [100] face of the aforementioned zinc oxide particle is 200 nm or more. A method for producing the aforementioned zinc oxide particle, which includes a step of firing a zinc compound in the presence of a molybdenum compound. A resin composition which contains the aforementioned zinc oxide particle and a resin.

Description

Technical Field

[0001] This invention relates to zinc oxide particles, a method for manufacturing zinc oxide particles, and a resin composition.

[0002] This application claims priority based on Japanese Patent Application No. 2020-167633, filed on October 2, 2020, the contents of which are incorporated herein by reference. Background Technology

[0003] Previously, the demand for miniaturization, lightweighting, and high performance in equipment has been accompanied by the advancement of high integration and large capacity in semiconductor devices. Consequently, the heat generated in the components of these devices has increased, necessitating improvements in heat dissipation. One known method for improving heat dissipation is to impart thermal conductivity to insulating components; more specifically, this involves adding a heat-dissipating filler with high thermal conductivity to the resin that forms the insulating component. Examples of heat-dissipating fillers used in this context include particles of alumina, magnesium oxide, boron nitride, aluminum nitride, and magnesium carbonate.

[0004] Alumina and magnesium oxide particles are the most common heat dissipation fillers. However, alumina particles have a high hardness (Mohs hardness: 9), raising concerns about potential wear on the metal components of mixers and molding machines. On the other hand, while magnesium oxide has a lower hardness (Mohs hardness: 6), its water resistance is problematic, hindering its widespread application. Therefore, a filler with higher thermal conductivity than both alumina and magnesium oxide particles, reduced concerns about wear on the target metal materials, and excellent water resistance is sought.

[0005] On the other hand, zinc oxide particles have a wide range of applications, such as in rubber vulcanization accelerators, printing inks, coatings, catalysts, and pigments. Furthermore, in recent years, the high thermal conductivity of zinc oxide has been recognized as a potential heat dissipation filler. Zinc oxide has a Mohs hardness of 4–5, making it softer than alumina.

[0006] For example, Patent Document 1 discloses a scheme in which zinc oxide microparticles with particularly high anisotropy are precipitated by heating a mixture of zinc acetate compound and methanol.

[0007] Patent document 2 discloses the following scheme: zinc oxide nanoparticles are generated by introducing zinc vapor into an oxygen-containing plasma region.

[0008] Patent document 3 discloses the following scheme: generating ultrafine zinc oxide by calcining a zinc compound.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2003-034529

[0012] Patent Document 2: Japanese Patent Application Publication No. 2005-213067

[0013] Patent Document 3: Japanese Patent Application Publication No. 2007-297260 Summary of the Invention

[0014] The problem the invention aims to solve

[0015] However, the average particle size of the zinc oxide particles disclosed in Patent Documents 1 to 3 is less than 100 nm, and the crystallite diameter is also less than 100 nm, so it is impossible to expect excellent crystallinity and excellent thermal conductivity.

[0016] Therefore, the object of the present invention is to provide zinc oxide particles with a larger crystallite diameter and superior thermal conductivity compared to conventional zinc oxide particles, a method for manufacturing the same, and a resin composition thereof.

[0017] Solution for solving the problem

[0018] The present invention includes the following methods.

[0019] [1] A type of zinc oxide particle, which is a polyhedral zinc oxide particle.

[0020] The microcrystal diameter of the

[100] face of the aforementioned zinc oxide particles is above 200 nm.

[0021] [2] According to the zinc oxide particles described in [1] above, wherein the microcrystal diameter of the

[101] face of the zinc oxide particles is 250 nm or more.

[0022] [3] According to the zinc oxide particles described in [1] or [2] above, wherein the median particle size D of the zinc oxide particles, calculated by laser diffraction / scattering method, is... 50 The range is 0.1–100 μm.

[0023] [4] The zinc oxide particles according to any one of [1] to [3] above, wherein the zinc oxide particles have a 10% particle size D calculated according to the laser diffraction / scattering method. 10 Median particle size D 50 and 90% of the particle size D 90 The dispersion index S calculated according to the following formula (1) is below 2.0.

[0024] S=(D 90 -D 10 ) / D 50 …(1)

[0025] [5] A method for manufacturing zinc oxide particles, which is the method for manufacturing zinc oxide particles described in any one of [1] to [4] above, the method comprising the following steps:

[0026] Zinc compounds are calcined in the presence of molybdenum compounds.

[0027] [6] The method for manufacturing zinc oxide particles according to the above [5] includes the following steps: mixing a zinc compound with a molybdate compound to form a mixture, and calcining the mixture.

[0028] [7] The method for manufacturing zinc oxide particles according to the above [6], wherein the aforementioned molybdate compound is lithium molybdate, potassium molybdate or sodium molybdate.

[0029] [8] A resin composition comprising: zinc oxide particles as described in any one of [1] to [4] above, and resin.

[0030] [9] The resin composition according to [8] above, wherein the resin is a thermoplastic resin.

[0031] The effects of the invention

[0032] According to the present invention, zinc oxide particles with larger crystal diameter and better thermal conductivity compared with conventional zinc oxide particles, a method for manufacturing the same, and a resin composition can be provided. Attached Figure Description

[0033] Figure 1 This is a SEM image of the zinc oxide particles from Example 1.

[0034] Figure 2 This is a SEM image of the zinc oxide particles from Example 2.

[0035] Figure 3 This is a SEM image of the zinc oxide particles from Example 3.

[0036] Figure 4 This is a SEM image of the zinc oxide particles from Example 4.

[0037] Figure 5 This is a SEM image of the zinc oxide particles from Example 5.

[0038] Figure 6 This is a SEM image of the zinc oxide particles from Example 6.

[0039] Figure 7 SEM images of zinc oxide particles from Comparative Example 1.

[0040] Figure 8 SEM images of zinc oxide particles from Comparative Example 2.

[0041] Figure 9 The image shows the X-ray diffraction (XRD) pattern of the zinc oxide particles in Example 1. Detailed Implementation

[0042] <Zinc Oxide Granules>

[0043] The zinc oxide particles in this embodiment are polyhedral zinc oxide particles, and the microcrystal diameter of the

[100] face of the aforementioned zinc oxide particles is 200 nm or more.

[0044] In this specification, the crystallite diameter of the

[100] plane of zinc oxide particles is the value of the crystallite diameter calculated using the Scherer formula, which is the half-width of the peak attributable to the

[100] plane (i.e., the peak that appears near 2θ = 31.8°) determined by X-ray diffraction (XRD).

[0045] The crystallite diameter of the

[100] facet of the zinc oxide particles in this embodiment is 200 nm or more, preferably 220 nm or more, more preferably 240 nm or more, and even more preferably 260 nm or more. The crystallite diameter of the

[100] facet of the zinc oxide particles in this embodiment can be 600 nm or less, 500 nm or less, 400 nm or less, or 340 nm or less. The crystallite diameter of the

[100] facet of the zinc oxide particles in this embodiment can be 200 nm or more and 600 nm or less, preferably 220 nm or more and 500 nm or less, more preferably 240 nm or more and 400 nm or less, and even more preferably 260 nm or more and 340 nm or less.

[0046] The zinc oxide particles of this embodiment are polyhedral in shape. By having a polyhedral shape, when the zinc oxide particles of this embodiment are used as an additive in a resin composite, facet contact between the particles in the resin composite becomes possible, thus resulting in excellent improvement in the thermal conductivity of the resin composite. It should be noted that in this specification, "polyhedral shape" refers to a hexahedron or more, preferably an octahedron or more, and more preferably a deca- to 30-sided polyhedron. Furthermore, the zinc oxide particles of this embodiment have a polyhedral shape formed by the following co-solvent method, thus forming a single-crystal structure. Phonon scattering is suppressed in the single-crystal structure, improving thermal conductivity.

[0047] The zinc oxide particles in this embodiment are polyhedral in shape. In the primary particles of the aforementioned zinc oxide, the area of ​​the largest flat surface is less than one-quarter, preferably less than one-fifth, more preferably less than one-sixth, and even more preferably less than one-eighth of the area of ​​the polyhedral particle. If the area of ​​the largest flat surface is less than one-quarter of the area of ​​the polyhedral particle, the shape is substantially close to a sphere, making it easier to fill with resin and improving the thermal conductivity of the resin composite. The aforementioned "area of ​​the largest flat surface" and "area of ​​the polyhedral particle" can also be estimated from SEM images.

[0048] The zinc oxide particles of this embodiment have large crystal diameters and high crystallinity on the

[100] face, thus exhibiting excellent thermal conductivity.

[0049] The crystallite diameter of the

[101] facet of the zinc oxide particles in this embodiment is preferably 250 nm or more, more preferably 260 nm or more, and even more preferably 270 nm or more. The crystallite diameter of the

[101] facet of the zinc oxide particles in this embodiment can be 500 nm or less, 400 nm or less, or 320 nm or less. The crystallite diameter of the

[101] facet of the zinc oxide particles in this embodiment is preferably 250 nm or more and 500 nm or less, more preferably 260 nm or more and 400 nm or less, and even more preferably 270 nm or more and 320 nm or less.

[0050] In this specification, the crystallite diameter of the

[101] plane of zinc oxide particles is the value of the crystallite diameter calculated using the Scherer formula, which is the half-width of the peak attributable to the

[101] plane (i.e., the peak that appears near 2θ = 36.3°) determined by X-ray diffraction (XRD).

[0051] In this embodiment, the microcrystal diameter of the

[100] face of the zinc oxide particles is 200 nm or more, and the microcrystal diameter of the

[101] face is 250 nm or more, thereby achieving high crystallinity and superior thermal conductivity.

[0052] The median particle size D of the zinc oxide particles in this embodiment, calculated using laser diffraction / scattering method, is... 50 Preferably 0.1–100 μm, more preferably 0.5–100 μm, more preferably 1.0–60 μm, and even more preferably 2.0–40 μm.

[0053] In this embodiment, the zinc oxide particles have a particle size D of 10% calculated based on laser diffraction / scattering. 10 Median particle size D 50 and 90% of the particle size D 90 The dispersion index S calculated according to the following formula (1) is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.6 or less.

[0054] S=(D 90 -D 10 ) / D 50 …(1)

[0055] The aforementioned 10% particle size D 10 The aforementioned median particle size D 50 and the aforementioned 90% particle size D 90Calculated using laser diffraction / scattering methods. Specifically, using a laser diffraction particle size distribution measuring device, such as the HELOS (H3355) & RODOS laser diffraction particle size analyzer, R3: 0.5 / 0.9-175μm (manufactured by Japan Laser Corporation), under dispersion pressure of 3 bar and input pressure of 90 mbar, the particle size distribution is measured dry to determine the 10% particle size D. 10 Median particle size D 50 and 90% of the particle size D 90 .

[0056] By making the dispersion index S of the zinc oxide particles in this embodiment 2.0 or less, it is easy to design resin filling when using them as an additive in resin composites. In addition, zinc oxide particles with a dispersion index S of 2.0 or less tend to have large crystallite diameters on the

[100] and

[101] faces, have high crystallinity, and have excellent effect on improving the thermal conductivity of resin composites.

[0057] The zinc oxide particles in this embodiment may contain molybdenum.

[0058] The molybdenum content determined by XRF analysis relative to 100% of zinc oxide particles is preferably 0–5.0% by mass, more preferably 0–3.0% by mass, and even more preferably 0–1.0% by mass.

[0059] The zinc oxide particles in this embodiment may also contain lithium, potassium, or sodium.

[0060] The average particle size of the primary zinc oxide particles can be 0.1–100.0 μm, 0.2–50.0 μm, or 0.5–20.0 μm.

[0061] The average primary particle size of zinc oxide particles is defined as follows: when zinc oxide particles are photographed using a scanning electron microscope (SEM), the major axis (Ferret diameter of the longest observed portion) and minor axis (the shorter Ferret diameter perpendicular to the Ferret diameter of the longest portion) of the particles constituting the aggregate (i.e., primary particles) in the two-dimensional image are measured, and the average of these values ​​is taken as the average primary particle size. This is the average primary particle size of 50 randomly selected primary particles.

[0062] The specific surface area of ​​zinc oxide particles, determined by the BET method, can range from 0.01 to 10.0 m². 2 / g, which can range from 0.02 to 5.0m 2 / g, which can be 0.05~2.0m 2 / g.

[0063] <Method for manufacturing zinc oxide granules>

[0064] The manufacturing method of this embodiment is the aforementioned method for manufacturing zinc oxide particles, and the manufacturing method includes the following steps: calcining a zinc compound in the presence of a molybdenum compound.

[0065] The method for manufacturing zinc oxide particles in this embodiment increases the crystallite diameter of the

[100] face of the zinc oxide particles by calcining a zinc compound in the presence of a molybdenum compound, thereby enabling the zinc oxide particles to form a polyhedral shape.

[0066] A preferred method for manufacturing zinc oxide particles includes the following steps: a step of mixing a zinc compound with a molybdenum compound to form a mixture (mixing step); and a step of firing the aforementioned mixture (firing step).

[0067] In a more preferred method for manufacturing zinc oxide particles, the aforementioned molybdenum compound is a molybdate compound, and the method includes the following steps: a step of mixing the zinc compound with the molybdate compound to form a mixture (mixing step); and a step of firing the aforementioned mixture (firing step).

[0068] [Mixed Process]

[0069] The mixing process is a process of mixing a zinc compound with a molybdenum compound to form a mixture. Preferably, the mixing process involves mixing a zinc compound with a molybdate compound to form a mixture. The contents of the mixture will be described below.

[0070] (Zinc compounds)

[0071] The zinc compound mentioned above is not limited to any compound that can form zinc oxide during firing. Examples of zinc compounds include zinc oxide, zinc acetate, and zinc hydroxide. Zinc oxide is preferred.

[0072] (Molybdenum compounds)

[0073] Examples of molybdenum compounds include molybdenum oxide and molybdate compounds.

[0074] Examples of molybdenum oxides include molybdenum dioxide and molybdenum trioxide, with molybdenum trioxide being preferred.

[0075] The aforementioned molybdate compound is MoO4. 2- Mo2O7 2- Mo3O 10 2- Mo4O 13 2- Mo5O 16 2- Mo6O 19 2- Mo7O 24 6-Mo8O 26 4- There are no restrictions on the salt compounds containing molybdenum oxyanions. They can be alkali metal salts containing molybdenum oxyanions, i.e., alkali metal salts of molybdate, alkaline earth metal salts of molybdate, or ammonium salts of molybdate.

[0076] Examples of alkali metal salts of molybdate include K₂MoO₄, K₂Mo₂O₇, and K₂Mo₃O₄. 10 K2Mo4O 13 K2Mo5O 16 K2Mo6O 19 K6Mo7O 24 K4Mo8O 26 Potassium molybdate; Na₂MoO₄ 2- Na2Mo2O7 2- Na2Mo3O 10 2- Na2Mo4O 13 2- Na2Mo5O 16 2- Na2Mo6O 19 2- Na6Mo7O 24 6- Na4Mo8O 26 4- Sodium molybdate salts; Li₂MoO₄, Li₂Mo₂O₇, Li₂Mo₃O 10 Li2Mo4O 13 Li2Mo5O 16 Li2Mo6O 19 Li6Mo7O 24 Li4Mo8O 26 Lithium molybdate salt.

[0077] As the aforementioned molybdate compound, an alkali metal salt of molybdate is preferred, and lithium molybdate, potassium molybdate, or sodium molybdate is more preferred.

[0078] Alkali metal molybdates can also remain non-vaporized within the firing temperature range and can be easily recovered through cleaning after firing. Therefore, the amount of molybdenum compounds released outside the firing furnace is reduced, which can also significantly reduce production costs.

[0079] In the method for manufacturing zinc oxide particles according to this embodiment, when the aforementioned molybdate compound is an alkali metal salt, the mixture of zinc compound and alkali metal molybdate can also be considered as containing both molybdenum compound and alkali metal compound under calcination conditions. The molybdenum compound (e.g., molybdenum oxide) reacts with the alkali metal compound (e.g., alkali metal carbonate, alkali hydroxide, alkali metal nitrate, or alkali metal oxide) to form alkali metal molybdate. The alkali metal molybdate acts as both a cosolvent and a shape control agent.

[0080] In the method for manufacturing zinc oxide particles according to this embodiment, the aforementioned molybdate compound can be a hydrate.

[0081] In the method for manufacturing zinc oxide particles according to this embodiment, a molybdenum compound is used as a co-solvent. In this specification, the manufacturing method using a molybdenum compound as a co-solvent will sometimes be simply referred to as the "co-solvent method".

[0082] It is believed that through the above-mentioned firing process, the molybdenum compound and the zinc compound interact, and under the action of the molybdenum compound as a co-solvent, polyhedral zinc oxide particles are formed.

[0083] In the method for manufacturing zinc oxide particles according to this embodiment, the mixing amounts of zinc compound and molybdate compound are not particularly limited. Preferably, a mixture is formed by mixing 35% or more of zinc compound and 65% or less of molybdate compound relative to 100% by mass of the aforementioned mixture, and the mixture can then be calcined. More preferably, a mixture is formed by mixing 40% or more and 99% or less of zinc compound and 0.5% or more and 60% or less of molybdate compound relative to 100% by mass of zinc oxide particles, and the mixture can then be calcined. Even more preferably, a mixture is formed by mixing 45% or more and 95% or less of zinc compound and 2% or more and 55% or less of molybdate compound relative to 100% by mass of zinc oxide particles, and the mixture can then be calcined.

[0084] By using various compounds within the above range, the polyhedral shape of the obtained zinc oxide particles can be well formed, and zinc oxide particles with a microcrystal diameter of 200 nm or more on the

[100] face can be manufactured.

[0085] [Firing process]

[0086] The calcination process is the process of calcining the aforementioned mixture. The zinc oxide particles of the embodiment are obtained by calcining the aforementioned mixture. As described above, this manufacturing method is called the fluxing method.

[0087] The co-solvent method is divided into solution methods. More specifically, the co-solvent method utilizes a solute-co-solvent binary system state diagram to represent the growth of eutectic crystals. The mechanism of the co-solvent method is as follows: A mixture of solute and co-solvent is gradually heated, causing both to become liquid phases. At this point, the co-solvent acts as a solvent; therefore, in other words, the solute-co-solvent binary system state diagram represents a eutectic phase. Thus, the solute melts at a temperature below its melting point, becoming a liquid phase. In this state, when the co-solvent is evaporated, its concentration decreases; in other words, the melting point lowering effect of the solute produced by the co-solvent is reduced. The evaporation of the co-solvent becomes the driving force, inducing crystal growth of the solute (co-solvent evaporation method). It should be noted that crystal growth of the solute can also be induced by cooling the liquid phase (slow cooling method).

[0088] The fluxing method has advantages such as: crystal growth can be carried out at temperatures far below the melting point; crystal structure can be precisely controlled; and polyhedral crystals with their own shape can be formed.

[0089] In the manufacture of zinc oxide particles using a co-solvent method employing molybdate compounds as co-solvents, the mechanism is not necessarily clear, but it is presumed to be based on, for example, the following mechanism: When a zinc compound is calcined in the presence of a molybdate compound, the molybdate compound interacts with the zinc compound, and as understood from the above description, zinc oxide crystals grow at a temperature lower than the melting point of zinc oxide. Furthermore, by calcining at high temperatures, the molybdate compound functions as both a co-solvent and a shape control agent, thereby controlling the crystal growth of zinc oxide and obtaining the polyhedral-shaped zinc oxide particles of the embodiments described. In other words, the molybdate compound functions as both a co-solvent and a shape control agent to manufacture zinc oxide particles.

[0090] The zinc oxide particles described above, which are polyhedral in shape and have a crystallite diameter of 200 nm or more on the

[100] facet, can be manufactured using the fluxing method described in this embodiment. Furthermore, the zinc oxide particles obtained by the fluxing method have a polyhedral shape, thus forming a single-crystal structure. The zinc oxide particles may also contain molybdenum.

[0091] There are no particular limitations on the firing method; any commonly known method can be used. If the firing temperature exceeds 650°C, an interaction occurs between the zinc compound and the molybdate compound. Furthermore, if the firing temperature reaches 800°C or higher, the zinc compound functions as a cosolvent and shape control agent, thereby forming zinc oxide particles.

[0092] Furthermore, the state of the zinc compound and molybdate compound is not particularly limited during firing, as long as the molybdate compound exists in the same space where it can act on the zinc compound. Specifically, it can be a simple mixing of powders of molybdate compound and zinc compound, or a mixing of powders of molybdenum oxide, alkali metal compound and zinc compound, mechanical mixing using a pulverizer, mixing using a mortar, etc., or mixing in a dry or wet state.

[0093] There are no particular limitations on the firing temperature; it can be appropriately determined based on factors such as the average particle size of the target zinc oxide particles, the formation and dispersibility of molybdenum compounds within the zinc oxide particles, etc. Generally, a firing temperature of 800°C or higher, close to the minimum temperature at which the target zinc oxide particles can be formed, is preferred.

[0094] Typically, to control the shape of zinc oxide obtained after firing, high-temperature firing at temperatures above 1500°C, close to the melting point of zinc oxide, is required. However, this presents significant challenges for industrial application due to the load on the firing furnace and fuel costs.

[0095] The manufacturing method of the present invention can be implemented even at high temperatures exceeding 1500°C, but at temperatures far below the melting point of zinc oxide, such as below 1300°C, regardless of the shape of the precursor, zinc oxide particles with large

[100] -face crystal diameters and

[101] -face crystal diameters and polyhedral shapes can be formed.

[0096] According to one embodiment of the present invention, under the condition of a maximum firing temperature of 800 to 1400°C, it is also possible to form zinc oxide particles with large crystal diameters on the

[100] face and

[101] face and large polyhedral shape at low cost and efficiency. Firing at a maximum temperature of 850 to 1300°C is more preferred, and firing in the range of 900 to 1200°C is most preferred.

[0097] From the perspective of manufacturing efficiency, the heating rate can be 20-600℃ / min, 40-500℃ / min, or 80-400℃ / min.

[0098] Regarding the firing time, it is preferable to raise the temperature to the specified maximum temperature within the range of 15 minutes to 10 hours, and to hold the maximum firing temperature within the range of 5 minutes to 30 hours. For effective formation of zinc oxide particles, a firing holding time of approximately 10 minutes to 15 hours is more preferable.

[0099] By selecting firing conditions of 1000–1400℃ and a holding time of 10 minutes–15 hours, it is easy to obtain zinc oxide particles with a polyhedral shape containing molybdenum, which are difficult to aggregate.

[0100] As for the firing atmosphere, there is no particular limitation as long as the effect of the present invention is obtained. For example, an oxygen-containing atmosphere such as air or oxygen, a non-reactive atmosphere such as nitrogen, argon, or carbon dioxide are preferred. Considering cost, an air atmosphere is more preferred.

[0101] The apparatus used for firing is not limited and any type of firing furnace can be used. The firing furnace is preferably made of a material that does not react with the sublimated molybdenum oxide, and it is even more preferable to use a firing furnace with high airtightness to effectively utilize the molybdenum oxide.

[0102] [Molybdenum Removal Process]

[0103] The method for manufacturing zinc oxide particles in this embodiment may, as needed, include a molybdenum removal process after the calcination step to remove at least a portion of the molybdenum.

[0104] In the method for manufacturing zinc oxide particles according to this embodiment, by controlling the firing time, firing temperature, etc., the molybdenum content present on the surface of the zinc oxide particles can be controlled. In addition, the molybdenum content and its state of existence outside the surface (inner layer) of the zinc oxide particles can be controlled.

[0105] Molybdenum can adhere to the surface of zinc oxide particles. This molybdenum can be removed by washing with water, ammonia solution, sodium hydroxide solution, or acidic aqueous solution. It should be noted that molybdenum may not be removed from the zinc oxide particles, but if at least the surface molybdenum is removed, when dispersed in a dispersion medium based on various binders, the original properties of zinc oxide can be fully utilized, and the adverse effects caused by the molybdenum present on the surface will not occur, which is therefore preferred.

[0106] At this point, the molybdenum content can be controlled by appropriately changing the concentration, dosage, cleaning location, and cleaning time of the water, ammonia solution, sodium hydroxide solution, and acidic solution used.

[0107] [Grinding Process]

[0108] The zinc oxide particles obtained after the firing process sometimes aggregate and do not meet the particle size range suitable for the present invention. Therefore, the zinc oxide particles can be pulverized as needed to meet the particle size range suitable for the present invention.

[0109] There are no particular limitations on the method of pulverizing the calcined material. Commonly known pulverizing methods such as ball mills, jaw crushers, spray mills, disc mills, spectrum mills, grinders, and mixing mills can be used.

[0110] [Grading process]

[0111] Zinc oxide particles are preferably graded to improve the average particle size, powder flowability, or to suppress viscosity increase when compounded with binders used to form a matrix. "Grading" refers to the process of grouping particles according to their size.

[0112] Classification can be either wet or dry, but from a productivity standpoint, dry classification is preferred. Dry classification includes methods such as sieve classification and air classification, which utilizes the difference between centrifugal force and fluid resistance. However, from a classification accuracy standpoint, air classification is preferred. This can be performed using classifiers that utilize the wall effect, such as airflow classifiers, swirling airflow classifiers, forced vortex centrifugal classifiers, and semi-free vortex centrifugal classifiers.

[0113] The aforementioned crushing and grading processes can be carried out at the desired stages. The selection of these crushing and grading processes, and the conditions involved, can, for example, adjust the average particle size of the resulting zinc oxide particles.

[0114] The zinc oxide particles of the present invention, or the zinc oxide particles obtained by the manufacturing method of the present invention, exhibit low or no aggregation, while readily exhibiting their original properties. They possess superior operability and are preferred from the viewpoint of superior dispersibility when dispersed in a dispersion medium. In the manufacturing method of zinc oxide particles, if the aforementioned pulverization and classification processes are omitted, and particles exhibiting low or no aggregation are obtained, the aforementioned processes are unnecessary. This allows for the high-productivity production of zinc oxide particles with the desired superior properties, which is therefore preferable.

[0115] <Resin Composition>

[0116] The resin composition of this embodiment contains: the aforementioned zinc oxide particles and resin.

[0117] In the resin composition of this embodiment, the aforementioned zinc oxide particles function as a heat dissipation filler. The aforementioned zinc oxide particles have large crystal diameters and high crystallinity on the

[100] facets. Furthermore, they are polyhedral in shape. Therefore, it is believed that when the aforementioned zinc oxide particles come into contact with each other in the resin composition, they achieve surface contact with high thermal conductivity. It is believed that, compared with resin compositions containing spherical zinc particles, even with the same filling ratio, high thermal conductivity can be obtained.

[0118] The resin in the resin composition of this embodiment can be a thermosetting resin or a thermoplastic resin.

[0119] (Thermosetting resin)

[0120] Thermosetting resins are resins that, when cured by heating, radiation, catalysts, or other means, become substantially insoluble and infusible. Examples include commonly known resins used in molding materials. Specifically, examples include phenolic varnish resins such as phenolic varnish resins and cresol varnish resins; unmodified first-stage phenolic resins and oil-modified first-stage phenolic resins modified with tung oil, linseed oil, walnut oil, etc.; bisphenol-type epoxy resins such as bisphenol A epoxy resins and bisphenol F epoxy resins; and phenolic varnish-type epoxy resins such as aliphatic chain modified bisphenol-type epoxy resins, phenolic varnish epoxy resins, and cresol varnish epoxy resins. Epoxy resins; biphenyl-type epoxy resins, polyalkylene glycol-type epoxy resins, etc.; urea (urea) resins, melamine resins, and other resins with triazine rings; (meth)acrylic resins, vinyl ester resins, and other vinyl resins; unsaturated polyester resins, bismaleimide resins, polyurethane resins, diallyl phthalate resins, silicone resins, resins with benzoxazine rings, cyanate ester resins, etc., which can be polymers, oligomers, or monomers.

[0121] The aforementioned thermosetting resin can be used in conjunction with a curing agent. The curing agent used in this case can be used in combinations commonly known to be used with thermosetting resins. For example, if the thermosetting resin is an epoxy resin, compounds commonly used as curing agents can be used, such as amine compounds, amide compounds, acid anhydride compounds, phenolic compounds, etc. Specifically, examples of amine compounds include diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenyl sulfone, isophorone diamine, imidazole, BF3-amine complexes, and guanidine derivatives. Examples of amide compounds include dicyandiamide and polyamide resins synthesized from linolenic acid dimers and ethylenediamine. Examples of anhydride compounds include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnorbornene anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride. Examples of phenolic compounds include phenolic varnish resins, cresol phenolic varnish resins, aromatic hydrocarbon formaldehyde resin modified phenolic resins, dicyclopentadiene phenol addition-type resins, and benzene. Polyphenolic compounds, such as xylok resin and resorcinol phenolic varnish resin, are synthesized from polyhydroxy compounds and formaldehyde, including polyphenolic varnish resins, naphthol alkyl resins, trimethylolmethane resin, tetrahydroxyphenylethane resin, naphthol phenolic varnish resin, naphthol-phenol cocondensed phenolic varnish resin, naphthol-cresol cocondensed phenolic varnish resin, biphenyl-modified phenolic resin (a polyphenolic compound with a phenol nucleus linked by dimethylene groups), biphenyl-modified naphthol resin (a polyphenolic compound with a phenol nucleus linked by dimethylene groups), aminotriazine-modified phenolic resin (a polyphenolic compound with a phenol nucleus linked by melamine, benzoguanamine, etc.), and alkoxy-containing aromatic ring-modified phenolic varnish resin (a polyphenolic compound with a phenol nucleus and an alkoxy-containing aromatic ring linked by formaldehyde). These curing agents can be used alone or in combination of two or more.

[0122] In this embodiment, the mixing amount of thermosetting resin and the aforementioned curing agent in the resin composition is not particularly limited. For example, when the curing resin is epoxy resin, from the viewpoint of obtaining good cured product properties, it is preferable to use an amount of 0.7 to 1.5 equivalents of active groups in the curing agent relative to the total amount of epoxy groups of epoxy resin.

[0123] Furthermore, a curing accelerator may be appropriately incorporated into the thermosetting resin in the resin composition of this embodiment, as needed. For example, when the curing resin is an epoxy resin, various substances can be used as the curing accelerator, such as phosphorus compounds, tertiary amines, imidazoles, organic acid metal salts, Lewis acids, and amine complex salts.

[0124] Additionally, as needed, a curing catalyst may be used in conjunction with the thermosetting resin in this embodiment. Commonly known thermal polymerization initiators and active energy radiation polymerization initiators can be cited as examples.

[0125] <Thermoplastic Resins>

[0126] The resin used in the resin composition of this embodiment is preferably a thermoplastic resin. The thermoplastic resin used in this embodiment is a commonly known resin used in molding materials and the like. Specifically, examples include polyethylene resin, polypropylene resin, polymethyl methacrylate resin, polyvinyl acetate resin, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride resin, polystyrene resin, polyacrylonitrile resin, polyamide resin, polycarbonate resin, polyacetal resin, polyethylene terephthalate resin, polyphenylene ether resin, polyphenylene sulfide (PPS) resin, polysulfone resin, polyethersulfone resin, polyetheretherketone resin, polyallyl sulfone resin, thermoplastic polyimide resin, thermoplastic urethane resin, polyaminobismaleimide resin, polyamide-imide resin, polyetherimide resin, bismaleimide triazine resin, polymethylpentene resin, fluorinated resin, liquid crystal polymer, olefin-vinyl alcohol copolymer, ionomer resin, polyacrylate resin, acrylonitrile-ethylene-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene copolymer, etc. At least one thermoplastic resin may be selected for use, but two or more thermoplastic resins may also be used in combination depending on the purpose.

[0127] Of the aforementioned resins, the combination of epoxy resin and curing agent, and polyphenylene sulfide (PPS) resin are more preferred in terms of excellent dimensional stability and heat resistance. Among these, the combination of epoxy resin and curing agent is the best as it provides the best thermal conductivity in absolute terms.

[0128] The resin composition of this embodiment may contain other compounding agents as needed. External lubricants, internal lubricants, antioxidants, flame retardants, light stabilizers, ultraviolet absorbers, reinforcing materials such as glass fiber and carbon fiber, fillers, and various colorants may be added without impairing the effects of the invention. Additionally, low-stress agents (stress relievers) such as silicone oil, liquid rubber, rubber powder, butadiene-based copolymer rubbers such as methyl acrylate-butadiene-styrene copolymer and methyl methacrylate-butadiene-styrene copolymer, and organosilicon compounds may also be used.

[0129] The resin composition of this embodiment can be obtained by mixing the aforementioned zinc oxide particles, resin, and other necessary blends. There are no particular limitations on the mixing method; mixing can be performed according to commonly known methods.

[0130] A common method when the resin is a thermosetting resin is to thoroughly mix a specified amount of thermosetting resin with the aforementioned zinc oxide particles and other desired components using a mixer, and then knead the mixture using a three-roll mill or similar method to form a fluid liquid composition. Alternatively, a specified amount of thermosetting resin with the aforementioned zinc oxide particles and other desired components can be thoroughly mixed using a mixer, and then melt-kneaded in a mixing roller, extruder, or similar method, followed by cooling to obtain a solid composition. The mixing state is simply to ensure that the curable resin is thoroughly and uniformly mixed with these mixtures when a curing agent or catalyst is added; more preferably, the aforementioned zinc oxide particles are also uniformly dispersed and mixed.

[0131] A common method when the resin is a thermoplastic resin is as follows: The thermoplastic resin, the aforementioned zinc oxide granules, and other required components are pre-mixed using various mixers such as drum mixers and Henschel mixers. Then, the mixture is melt-blended using mixers such as Banbury internal mixers, roller mixers, Brabender powder analyzers, single-screw compounding extruders, twin-screw compounding extruders, kneaders, and mixing rollers. It should be noted that there are no particular limitations on the melt-blending temperature, which is typically in the range of 240–320°C.

[0132] The mixing ratio of the aforementioned zinc oxide particles to the non-volatile components of the resin when preparing the resin composition of this embodiment is not particularly limited, but is preferably selected from the range of 66.7 to 900 parts per 100 parts by mass of the non-volatile components of the resin. Furthermore, the content of the aforementioned zinc oxide particles in the resin composition of this embodiment is not particularly limited, and is mixed according to the required thermal conductivity for each application; preferably, the content of the aforementioned zinc oxide particles is 30 to 90 parts by volume per 100 parts by volume of the resin composition.

[0133] To effectively realize the function of the aforementioned zinc oxide particles as a thermally conductive filler and obtain high thermal conductivity, it is preferable to have a high filler content of the aforementioned zinc oxide particles. More preferably, the content of the aforementioned zinc oxide particles in 100 parts by volume of the resin composition is 40 to 90 parts by volume. When the resin in the resin composition is a thermosetting resin, considering its flowability, it is further preferable that the content of the aforementioned zinc oxide particles in 100 parts by volume of the resin composition is 60 to 85 parts by volume.

[0134] Example

[0135] Next, embodiments will be shown to further illustrate the invention in detail, but the invention is not limited to the following embodiments.

[0136] [Comparative Example 1]

[0137] Zinc oxide (ZnO) (and photochemical reagent) was used as zinc oxide particles in Comparative Example 1. SEM images of the zinc oxide particles from Comparative Example 1 are shown below. Figure 7 The particles are amorphous.

[0138] [Comparative Example 2]

[0139] (Manufacturing of zinc oxide granules)

[0140] Place 10.0 g of zinc oxide (ZnO) (and light-reflecting agent) in an alumina crucible and perform heat treatment under the following conditions.

[0141] (Heat treatment)

[0142] Using a heating furnace SC-2045D-SP manufactured by Motoyama Corporation, the temperature was increased from room temperature to 1100°C at a rate of 300°C / hour, held at 1100°C for 10 hours, and then decreased at a rate of 200°C / hour.

[0143] SEM images of the zinc oxide particles obtained in Comparative Example 2 are shown below. Figure 8 Compared with the zinc oxide particles of Comparative Example 1, it can be confirmed that the zinc oxide particles of Comparative Example 2 have grown in size and become sintered. However, the particle shape remains amorphous.

[0144] [Example 1]

[0145] (Manufacturing of zinc oxide granules)

[0146] Measure 10.0 g of zinc oxide (ZnO) (and light-reflecting reagent) and 10.0 g of lithium molybdate (Li2MoO4) into a container and mix them in a mortar for 10 minutes. Place the resulting 20.0 g mixture into an alumina crucible and heat-treat it under the following conditions.

[0147] (Heat treatment)

[0148] Using a heating furnace SC-2045D-SP manufactured by Motoyama Corporation, the temperature was increased from room temperature to 1100°C at a rate of 300°C / hour, held at 1100°C for 10 hours, and then decreased at a rate of 200°C / hour.

[0149] (Subsequent processes)

[0150] The solid obtained from the sagger was coarsely pulverized and then 150 mL of pure water was added. The mixture was stirred at room temperature for 3 hours to dissolve the water-soluble components. The liquid was then separated and discarded. The solid was further washed twice with 150 mL of water, the liquid was separated and discarded, and then dried at 130 °C for 6 hours.

[0151] SEM images of the zinc oxide particles obtained in Example 1 are shown below. Figure 1Zinc oxide particles with a near-cubic polyhedral shape were observed.

[0152] [Example 2]

[0153] (Manufacturing of zinc oxide granules)

[0154] In Example 1, 10.0 g of lithium molybdate (Li₂MoO₄) was replaced with 10.0 g of potassium molybdate (K₂MoO₄); otherwise, zinc oxide particles were manufactured in the same manner as in Example 1. SEM images of the zinc oxide particles obtained in Example 2 are shown below. Figure 2 Polyhedral zinc oxide particles were observed.

[0155] [Example 3]

[0156] (Manufacturing of zinc oxide granules)

[0157] In Example 1, 10.0 g of lithium molybdate (Li₂MoO₄) was replaced with 12.0 g of sodium molybdate dihydrate (Na₂MoO₄·2H₂O). Otherwise, zinc oxide particles were manufactured in the same manner as in Example 1. SEM images of the zinc oxide particles obtained in Example 3 are shown below. Figure 3 Polyhedral zinc oxide particles were observed.

[0158] [Example 4]

[0159] (Manufacturing of zinc oxide granules)

[0160] In Example 1, the heat treatment conditions were set as follows: heating from room temperature to 800°C at a rate of 300°C / hour, and holding at 800°C for 10 hours. Otherwise, zinc oxide particles were manufactured in the same manner as in Example 1. SEM images of the zinc oxide particles obtained in Example 4 are shown below. Figure 4 Polyhedral zinc oxide particles were observed.

[0161] [Example 5]

[0162] (Manufacturing of zinc oxide granules)

[0163] In Example 1, the heat treatment conditions were set as follows: heating from room temperature to 900°C at a rate of 300°C / hour, and holding at 900°C for 10 hours. Otherwise, zinc oxide particles were manufactured in the same manner as in Example 1. SEM images of the zinc oxide particles obtained in Example 5 are shown below. Figure 5 Polyhedral zinc oxide particles were observed.

[0164] [Example 6]

[0165] (Manufacturing of zinc oxide granules)

[0166] Measure 180.0 g of zinc oxide granules (and light-reflecting reagent) and 140.0 g of sodium molybdate dihydrate (Na2MoO4·2H2O) into a container. After thoroughly dispersing with an absolute mill for 10 seconds, scrape off the material adhering to the wall three times. Separate and recover 21 g, place it in an alumina crucible, and heat treat it under the following conditions.

[0167] (Heat treatment)

[0168] Using a heating furnace SC-2045D-SP manufactured by Motoyama Corporation, the temperature was increased from room temperature to 1100°C at a rate of 300°C / hour, held at 1100°C for 10 hours, and then decreased at a rate of 200°C / hour.

[0169] (Subsequent processes)

[0170] The solid obtained from the sagger was coarsely pulverized, and then 150 mL of pure water was added. After stirring for 15 minutes, it was placed in an oven heated to 90°C for 3 hours to dissolve the water-soluble substances. The liquid was then separated and discarded. The solid was further washed twice with 150 mL of water, and the liquid was separated and discarded. Finally, it was dried at 130°C for 6 hours.

[0171] SEM images of the zinc oxide particles obtained in Example 6 are shown below. Figure 6 Polyhedral zinc oxide particles were observed.

[0172] The composition and maximum sintering temperature of each mixture from Comparative Examples 1-2 and Examples 1-6 are shown in Table 1.

[0173] [Determination of the average particle size of primary zinc oxide particles]

[0174] Zinc oxide particles were imaged using a scanning electron microscope (SEM). For the smallest unit of the aggregate (i.e., primary particles) in the two-dimensional image, their major axis (the Ferete diameter of the longest observed portion) and minor axis (the shorter Ferete diameter perpendicular to the Ferete diameter of the longest portion) were measured, and their average was taken as the primary particle size. The same operation was performed on 50 randomly selected primary particles, and the average particle size of the primary particles was calculated from the average of the primary particle sizes of these primary particles. The results are shown in Table 1.

[0175] [Determination of crystallite diameter]

[0176] X-ray diffraction apparatus (Rigaku Corporation, SmartLab) equipped with a high-intensity / high-resolution crystallization analyzer (CALSA) as the detector was used to perform powder X-ray diffraction (2θ / θ method) measurements under the following conditions. Analysis was performed using the CALSA function of the analysis software (PDXL) manufactured by Rigaku Corporation. The crystallite diameter for the

[100] plane was calculated using the Scherer formula from the half-width of the peak appearing near 2θ = 31.8°, and the crystallite diameter for the

[101] plane was calculated using the Scherer formula from the half-width of the peak appearing near 2θ = 36.3°. The results are shown in Table 1.

[0177] (Determination conditions of powder X-ray diffraction)

[0178] Tube voltage: 45kV

[0179] Tube current: 200mA

[0180] Scanning speed: 0.05° / minute

[0181] Scanning range: 10–70°

[0182] Step size: 0.002°

[0183] βs: 20 rpm

[0184] The standard amplitude of the device is 0.026°, calculated using standard silicon powder (NIST, 640d) produced by the National Institute of Standards and Technology (NIST).

[0185] [Crystal Structure Analysis: XRD (X-ray Diffraction) Method]

[0186] The zinc oxide particle sample from Example 1 was filled to a depth of 0.5 mm into a sample holder for measurement and mounted on a wide-angle X-ray diffraction (XRD) apparatus (Ultima IV, Rigaku Corporation). Measurements were performed under Cu / Kα radiation, 40 kV / 40 mA, a scan rate of 2° / min, and a scan range of 10–70°. The XRD results of the zinc oxide particles from Example 1 are shown below. Figure 9 .

[0187] Peaks were observed at 2θ = 31.79° (

[100] plane), 34.44° (

[002] plane), 36.27° (

[101] plane), 47.56°, 56.61°, 62.87°, 66.39°, 67.96°, and 69.69°. These peaks can be indexed on the crystal planes of the wurtzite structure of zinc oxide (JSPDF File No. 79-2205).

[0188] [Particle size distribution determination of zinc oxide particles]

[0189] The particle size distribution was measured dry using a laser diffraction particle size analyzer (HELOS (H3355) & RODOS, R3: 0.5 / 0.9-175μm, manufactured by Japan Laser Corporation) under dispersion pressure of 3 bar and input pressure of 90 mbar. The 10% particle size D was then determined. 10 Median particle size D 50 and 90% of the particle size D 90 Furthermore, calculate (D) 90 -D 10 ) / D 50 The values ​​are shown in Table 1.

[0190] [Specific surface area determination of zinc oxide particles]

[0191] The specific surface area of ​​zinc oxide particles was determined using a specific surface area meter (MicrotracBEL, BELSORP-mini). The surface area per 1g of sample, calculated from the nitrogen adsorption amount based on the BET method, was taken as the specific surface area (m²). 2 / g). The results are shown in Table 1.

[0192] [Purity determination of zinc oxide particles: XRF (X-ray fluorescence) analysis]

[0193] Using a Primus IV fluorescence X-ray analysis apparatus (manufactured by Rigaku Corporation), approximately 70 mg of zinc oxide particles were measured on filter paper, covered with a PP film, and subjected to compositional analysis.

[0194] The amounts of zinc, molybdenum, and sodium, as determined by XRF analysis, were calculated relative to 100% by mass of zinc oxide particles, using conversions for zinc oxide (ZnO), molybdenum trioxide, and sodium oxide (Na₂O). The results are shown in Table 1.

[0195] [Table 1]

[0196]

[0197] [Example 7]

[0198] 7.29 parts by weight of polyphenylene sulfide resin (DIC-PPS LR100G) manufactured by DIC Corporation as a thermoplastic resin and 20.2 parts by weight of zinc oxide particles from Example 6 were uniformly dry-mixed and then melt-mixed using an Xplore MC15 melt-mixing apparatus at a mixing temperature of 300°C and a rotation speed of 100 rpm to obtain the polyphenylene sulfide resin composition of Example 7, in which the zinc oxide particles used as thermally conductive fillers were filled at a rate of 40% by volume.

[0199] [Comparative Example 3]

[0200] In Example 7, 20.2 parts by weight of zinc oxide particles from Example 6 were replaced with 13.43 parts by weight of spherical alumina particles (DAW-07) manufactured by Denka Co., Ltd. Otherwise, the same polyphenylene sulfide resin composition of Comparative Example 3 with a filling rate of 40% by volume of alumina particles as thermally conductive filler was obtained as in Example 7.

[0201] [Comparative Example 4]

[0202] In Example 7, 20.2 parts by weight of zinc oxide particles from Example 6 were replaced with 20.2 parts by weight of zinc oxide (ZnO) (and light-reflecting agent) from Comparative Example 1. Otherwise, the same polyphenylene sulfide resin composition as in Example 7 was obtained, with a filling rate of 40% by volume of zinc oxide particles as thermally conductive filler, as in Comparative Example 4.

[0203] (Production of injection-molded articles)

[0204] For each polyphenylene sulfide resin composition of Example 7 and Comparative Examples 3-4, injection molding was performed using an Xplore IM12 injection molding machine at a composition temperature of 320°C, a mold temperature of 140°C, an injection pressure of 10 bar, and a holding pressure of 11 bar. According to JIS K7161-2, dumbbell-shaped 5A test pieces (edge ​​width 12.5 mm, total length 75 mm, thickness 2 mm) of Example 7 and Comparative Examples 3-4 were obtained.

[0205] (Heat dissipation evaluation)

[0206] According to JIS R 1611, 10mm × 10mm × 2mm heat dissipation test pieces were cut from the dumbbell-shaped 5A test pieces of Examples 7 and Comparative Examples 3-4. The thermal diffusivity and specific heat at 25°C were measured using a thermal conductivity measuring device (LFA467 HyperFlash, NETZSCH). Next, the density of these heat dissipation test pieces was measured according to Archimedes' method. The thermal conductivity of the heat dissipation test pieces was calculated by multiplying the obtained thermal diffusivity, specific heat, and density. The results are shown in Table 2.

[0207] (Abrasion resistance evaluation)

[0208] Abrasion resistance test pieces of 10mm × 10mm × 2mm were cut from the dumbbell-shaped SA-shaped test pieces of Examples 7 and Comparative Examples 3 to 4.

[0209] For these wear resistance test pieces, a 1 kg load was applied and pressed onto an alloy tool steel (SKS2) tool with the 10 mm × 10 mm square face of the test piece in perpendicular contact with the cutting edge of the tool. The cutting edge of the tool was oriented parallel to one side of the 10 mm × 10 mm square, and the contact length between the cutting edge and the wear resistance test piece was 10 mm.

[0210] Next, under the conditions of a 100mm reciprocating movement distance and 75mm / s, the cutting edge was rubbed 1000 times. As a result, the initial cutting edge height H0 (80μm) of the cutting edge wore down and slowly shortened. The cutting edge height H1 after 1000 reciprocating friction cycles was measured.

[0211] The ratio of the height H1 of the cutting edge after the test to the length H0 (80 μm) of the initial cutting edge is calculated according to the following formula (2), which is the wear test retention rate R (%).

[0212] R(%)=H1 / H0×100…(2)

[0213] The greater the wear on the cutting edge of the tool, the smaller the wear retention rate R (%) in the wear test. The results are shown in Table 2.

[0214] [Table 2]

[0215] thermal conductivity W / mK 1.6 1.1 1.2 Wear test retention rate ％ 78 28 80

[0216] The results show that the injection-molded article obtained from the polyphenylene sulfide resin composition of Example 7 containing zinc oxide particles of Example 6 of the present invention has superior thermal conductivity compared with the injection-molded article obtained from the polyphenylene sulfide resin composition of Comparative Example 3 containing alumina particles and the injection-molded article obtained from the polyphenylene sulfide resin composition of Comparative Example 4 containing zinc oxide particles of Comparative Example 1.

[0217] This indicates that the injection-molded article obtained from the polyphenylene sulfide resin composition of Example 7 containing zinc oxide particles of Example 6 of the present invention reduces concerns about wear on the target metal material compared to the injection-molded article obtained from the polyphenylene sulfide resin composition of Comparative Example 3 containing alumina particles.

[0218] Industrial availability

[0219] The zinc oxide particles of this invention can be used as heat dissipation fillers, coatings, and pigments for cosmetics. The zinc oxide particles of this invention are particularly expected to be used as fillers in heat dissipation composites for polyphenylene sulfide (PPS), heat dissipation molded bodies, thermal interface material (TIM) sheets, heat dissipation adhesives, heat dissipation adhesive sheets, heat dissipation pastes for printed circuit boards (PCBs), highly flexible thermally conductive rubbers, heat dissipation greases, heat dissipation sealants, semiconductor sealing resins, and the like.

Claims

1. A type of zinc oxide granules, wherein the zinc oxide granules are in a polyhedral shape. The specific surface area of the zinc oxide particles, measured by the BET method, is 0.01 to 10.0 m 2 / g, The microcrystal diameter of the [100] facet of the zinc oxide particles is greater than 200 nm. The 10% particle diameter D10 of the zinc oxide particles calculated from the laser diffraction / scattering method 10 The median particle diameter D50 50 The 90% particle diameter D90 90 The dispersion index S calculated from the following formula (1) is 2.0 or less, S=(D 90 -D 10 ) / D 50 (1)。 2. The zinc oxide particles according to claim 1, wherein, The microcrystal diameter of the [101] face of the zinc oxide particles is above 250 nm.

3. The zinc oxide particles according to claim 1 or 2, wherein, The median particle size D of the zinc oxide particles, calculated using laser diffraction / scattering method. 50 The range is 0.1~100μm.

4. A method for manufacturing zinc oxide particles, which is the method for manufacturing zinc oxide particles according to any one of claims 1 to 3, the method comprising the following steps: The zinc compound is calcined in the presence of molybdate compounds.

5. The method for manufacturing zinc oxide particles according to claim 4, comprising the following steps: mixing a zinc compound with a molybdate compound to form a mixture, and calcining the mixture.

6. The method for manufacturing zinc oxide particles according to claim 5, wherein, The molybdate compound is lithium molybdate, potassium molybdate, or sodium molybdate.

7. A resin composition comprising: a resin and zinc oxide particles according to any one of claims 1 to 3.

8. The resin composition according to claim 7, wherein, The resin is a thermoplastic resin.

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