Spherical calcium titanate powder and resin composition

Abstract

The present disclosure provides: a spherical calcium titanate powder which has excellent resin filling properties and is capable of achieving a higher relative dielectric constant and a low dielectric loss tangent; and a resin composition containing the spherical calcium titanate powder. The spherical calcium titanate powder of the present disclosure has a ratio (D50 / BET) of an average particle diameter (D50: [mu] m) to a specific surface area (BET: m2 / g) of 10-20. A resin composition according to the present disclosure contains the spherical calcium titanate powder and at least one resin selected from the group consisting of thermoplastic resins and thermosetting resins.

Description

Technical Field

[0001] This disclosure relates to spherical calcium titanate powder and resin compositions. Background Technology

[0002] In recent years, with the increase in information communication volume in the communications field, high-frequency signals are being widely used in electronic and communication equipment. On the other hand, applying high-frequency signals to these devices can also lead to problems such as increased transmission loss of circuit signals.

[0003] Furthermore, with the increasing functionality of related electronic materials and components, there is a demand for further miniaturization of electronic and communication equipment. For communication equipment, increasing the relative permittivity of the antenna material assembled within it allows for further miniaturization. Therefore, a material (ceramic filler) capable of achieving both high relative permittivity and low dielectric loss tangent is required.

[0004] Furthermore, perovskite-type composite oxides are represented by barium titanate and strontium titanate, primarily denoted by ABO3. Due to the high relative permittivity of such perovskite-type composite oxide powders, they are expected to serve as ceramic fillers for next-generation electronic devices. Among them, titanium-based composite oxides exhibit excellent electrical properties such as dielectric, pyroelectric, and piezoelectric properties, and are therefore being used as electronic materials. Patent Document 1 describes a calcium titanate powder with high crystallinity and excellent electrical properties, and its manufacturing method.

[0005] Furthermore, ceramic fillers are mostly used in resins, so from the perspective of improving resin filling and dispersibility, thereby stabilizing dielectric properties, and also from the perspective of improving processability and workability, it is desirable for their shape to be closer to a sphere. Patent Document 1 describes calcium titanate powder with particles in the shape of cubic prisms or similar cubic prisms, and does not study powders containing spherical calcium titanate particles.

[0006] Existing technology

[0007] Patent Document 1: Japanese Patent Application Publication No. 2011-116645

[0008] Patent Document 2: Japanese Patent No. 4155750

[0009] Patent Document 3: Japanese Patent Application Publication No. 2012-246203 Summary of the Invention

[0010] The objective of this disclosure is to provide spherical calcium titanate powder with excellent resin filling properties, capable of achieving higher relative permittivity and low dielectric loss tangent, and a resin composition comprising the above-mentioned spherical calcium titanate powder.

[0011] After in-depth research, the inventors discovered that as long as the average particle size (D50: μm) is relative to the specific surface area (BET: m²), the following results can be obtained: 2 Spherical calcium titanate powder with a ratio (D 50 / BET) of 10 to 20 (d / g) exhibits excellent resin filling properties, enabling the achievement of higher relative permittivity and lower dielectric loss tangent. Furthermore, it has been found that resin compositions comprising the aforementioned spherical calcium titanate powder and at least one resin selected from thermoplastic and thermosetting resins are suitable for use as materials capable of achieving high relative permittivity and low dielectric loss tangent.

[0012] According to this disclosure, it is possible to provide spherical calcium titanate powder with excellent resin filling properties, which can achieve a higher relative permittivity and a low dielectric loss tangent, as well as a resin composition comprising the above-mentioned spherical calcium titanate powder. Detailed Implementation

[0013] The following is a detailed description of one embodiment of this disclosure; however, the scope of this disclosure is not limited to the single embodiment described herein, and various modifications can be made without departing from the spirit of this disclosure. The various methods disclosed in this specification can also be combined with any other features disclosed in this specification. Furthermore, for a specific parameter, when multiple upper and lower limits are described, any combination of these upper and lower limits can constitute a preferred numerical range. Additionally, the lower and / or upper limits of the numerical range described in this disclosure can be values ​​within that numerical range, or they can be replaced with the values ​​shown in the embodiments. The expression "X~Y" representing a numerical range means "X above Y below". In other embodiments, where a specific description described for one embodiment is also applicable, that description may be omitted.

[0014] The various components and combinations thereof in each embodiment are merely examples, and appropriate additions, omissions, substitutions, and other modifications can be made without departing from the spirit of this disclosure. This disclosure is not limited to the embodiments.

[0015] The various methods disclosed in this specification can also be combined with any other features disclosed in this specification.

[0016] In this specification, "powder" refers to an aggregate of multiple particles.

[0017] [Spherical calcium titanate powder]

[0018] The average particle size (D50: μm) of the spherical calcium titanate powder (hereinafter, there are also cases where it is referred to simply as "powder") related to this embodiment is relative to the specific surface area (BET: m²). 2The ratio of D50 / g (D50 / BET) is 10 to 20. The spherical calcium titanate powder of this embodiment can achieve a higher relative permittivity. Furthermore, it can also achieve a low dielectric loss tangent.

[0019] In this disclosure, "spherical powder" refers to powder in which the individual particles are observed to be spherical or have a rounded shape when viewed at 10,000x magnification using a scanning electron microscope. Since the powder in this embodiment is calcium titanate powder containing spherical particles, it also exhibits good resin filling properties.

[0020] The average particle size (D50: μm) of the spherical calcium titanate powder related to this embodiment is relative to the specific surface area (BET: m²). 2 The ratio of D50 to BET (μm / g) can be determined by measuring the average particle size (D50) (hereinafter, it may also be referred to as "D50") and specific surface area (BET) (hereinafter, it may also be referred to as "BET") using the methods described below. Then, the value of D50 (μm) is divided by the value of BET (m² / g). 2 The value of / g) is obtained by calculating it.

[0021] <Average particle size (D50)>

[0022] The average particle size (D50) of the spherical calcium titanate powder related to this embodiment (hereinafter, there may also be cases where it is referred to as "D50") can be measured according to the following conditions.

[0023] (Conditions for determining average particle size)

[0024] The average particle size was measured using a laser diffraction / scattering particle size distribution measuring device (e.g., the "MT 3300 EXII" manufactured by MicrotracBEL Co., Ltd.). First, 80 cm³ of the sample was placed in a glass beaker. 3 0.1 g of spherical calcium titanate powder was dispersed in pure water using an ultrasonic homogenizer (e.g., the trade name "UH-600S" manufactured by SMT Co., Ltd., with a homogenizer probe diameter of 20 mm φ) for 1 minute. The dispersion of the spherical calcium titanate powder was then added dropwise to a laser diffraction / scattering particle size distribution measuring device using a dropper. The average particle size was measured 30 seconds after the start of the specified addition. The particle size distribution was calculated based on the intensity distribution of diffracted / scattered light from the spherical calcium titanate powder detected by the sensor in the laser diffraction / scattering particle size distribution measuring device. D50 was calculated based on the cumulative particle size distribution corresponding to 50% of the particle size in the volumetric reference of the measured particle size. D50 (μm) was then expressed as a value with the second decimal place rounded to the first decimal place.

[0025] Specific surface area (BET)

[0026] The specific surface area of ​​the spherical calcium titanate powder described in this embodiment can be measured using the BET multi-point method with a fully automated specific surface area measuring device. Specifically, the measurement can be performed under the following conditions.

[0027] (Methods for determining specific surface area)

[0028] The BET specific surface area of ​​spherical calcium titanate powder was determined using the following method. First, 4 g of spherical calcium titanate powder was filled into an empty tank and degassed at 300°C. After degassed, the tank filled with the spherical calcium titanate powder was placed in a fully automated specific surface area measuring device (e.g., the "Macsorb Model 1208" manufactured by Mountech) for specific surface area measurement. A He-N2 mixed gas was used for measurement, and the measurement was performed at a main flow rate of 25 mL / min using a multi-point method.

[0029] The (D50 / BET) of the spherical calcium titanate powder in this embodiment is not particularly limited as long as it is in the range of 10 to 20, but from the viewpoint of easily achieving a higher relative permittivity, it is preferably 10 to 19. In one embodiment, from the viewpoint of easily obtaining powder with a lower dielectric loss tangent, (D50 / BET) can be 11 to 17, 12 to 19, 14 to 19, or 12 to 16.

[0030] Furthermore, for a D50 / BET ratio of 10 to 20, this can be easily achieved, for example, by further heating the spheroidized calcium titanate powder at a specific temperature to remove fine particles adhering to the particle surface, thereby reducing BET. Moreover, since the decrease in D50 and the increase in BET can be suppressed by not performing crushing treatment that would cause a change of more than 20% in the D50 of the heat-treated spheroidized calcium titanate powder, or by recovering the powder without crushing treatment, it is even easier to achieve this.

[0031] The D50 and BET ranges of the spherical calcium titanate powder can be arbitrarily adjusted within the range of (D50 / BET) of 10 to 20 mentioned above.

[0032] In one embodiment, from the viewpoint of easily obtaining powders with higher relative permittivity, the D50 of the spherical calcium titanate powder is preferably 0.5–15 μm. The D50 range can be 1–15 μm, 2–15 μm, 3–15 μm, 4–15 μm, 4–10 μm, 4–9 μm, 5–10 μm, 5–9 μm, or 6–9 μm.

[0033] Furthermore, from the viewpoint of easily obtaining powders with higher relative permittivity, the BET of the powder is preferably below 0.7 m. 2 / g, more preferably 0.5m 2 Below / g, further preferably below 0.5m 2 / g.

[0034] In this embodiment, the proportion of spherical calcium titanate powder particles having a diameter of 0.2 times the D50 is preferably a certain value or less. Since the proportion of small particles having a diameter of 0.2 times the D50 is relatively small, it is easier to achieve a higher relative permittivity. In one embodiment, the proportion of particles having a diameter of 0.2 times the D50 is preferably 1.5 vol% or less, more preferably 1.0 vol% or less, further preferably 0.8 vol% or less, and particularly preferably 0.6 vol% or less. The proportion of particles having a diameter of 0.2 times the D50 can also be 0.5 vol% or less. In another embodiment, the proportion of spherical calcium titanate powder particles having a diameter of 0.2 times the D50 can be 0 vol%. In this specification, "a particle proportion of 0 vol%" means that in the measurement using the laser diffraction / scattering particle size distribution measuring device described above, the cumulative value of a specific particle is 0 or the particle is not detected (below the measurement lower limit). Furthermore, the proportion of particles having a diameter of 0.2 times the D50 can be obtained by the following steps.

[0035] 1. Determine D50 according to the above "Determination conditions for average particle size".

[0036] 2. Multiply D50 by 0.2 to calculate the particle size. Then, round the second decimal place to the nearest whole number and calculate the particle size to one decimal place.

[0037] 3. Based on the cumulative particle size distribution of the volume criterion, determine the particle proportion of 0.2 times the particle size of D50 obtained in step 2 (the particle size after rounding the second decimal place of the particle size calculated by multiplying D50 by 0.2 above).

[0038] In this embodiment, when the D50 of the powder is 0.5 to 15 μm, the particle size that is 0.2 times the D50 is 0.1 to 3.0 μm. If the proportion of particles with such a particle size is 1.5 vol% or less, it is easy to control (D50 / BET) in the range of 10 to 20, and it is easy to obtain powder with a higher relative permittivity. Alternatively, the particle size that is 0.2 times the D50 can also be in the range of 1.0 to 1.8 μm.

[0039] When the powder of this embodiment has a D50 of 4 μm or more, more preferably in the range of 4 μm to 15 μm, the proportion of particles with a particle size of 2.0 μm or less is preferably a certain value or less. That is, when the powder has a D50 of 4 μm or more, as long as the proportion of particles with a particle size of 2.0 μm or less is a certain value or less, preferably 4.0 vol% or less, it is easy to control (D50 / BET) in the range of 10 to 20. As a result, it is easy to obtain powder with a higher relative permittivity. In addition, from the viewpoint of easily controlling (D50 / BET) in the range of 10 to 20, the proportion of particles with a particle size of 2.0 μm or less is preferably 3.0 vol% or less, more preferably 2.5 vol% or less, further preferably 2.0 vol% or less, and particularly preferably 1.5 vol% or less. Furthermore, the proportion of the above-mentioned particles may also be 1.0 vol% or less.

[0040] Similarly, from the viewpoint of easily controlling (D50 / BET) within the range of 10 to 20, when the D50 of the powder is 4 μm or more, the proportion of particles with a particle size of 1.0 μm or less is preferably below a certain value. In one embodiment, the proportion of particles with a particle size of 1.0 μm or less can be 1.0 vol% or less, or 0.5 vol% or less. Furthermore, the proportion of particles with a particle size of 1.0 μm or less in spherical calcium titanate powder can also be 0 vol%. In addition, the proportion of particles with a particle size of 2.0 μm or less and the proportion of particles with a particle size of 1.0 μm or less can be calculated from the cumulative value of particles with a particle size of 2.0 μm or less or the cumulative value of particles with a particle size of 1.0 μm or less, based on the particle size distribution on a volume basis measured according to the above-described average particle size measurement conditions.

[0041] Mean sphericity

[0042] The average sphericity of the spherical calcium titanate powder in this embodiment is preferably 0.80 or higher. An average sphericity of 0.80 or higher facilitates further improvement in resin filling and dispersibility. The average sphericity of the spherical calcium titanate powder can be 0.85 or higher, 0.86 or higher, or 0.87 or higher. In one embodiment, the average sphericity of the powder can be in the range of 0.84 or higher and lower than 0.90. Furthermore, the average sphericity of the spherical calcium titanate powder can be measured by the following method.

[0043] (Method for determining mean sphericity)

[0044] The determination is performed using a powder imaging analyzer (e.g., the Spectris "FPIA-3000"), following these steps.

[0045] The sample was dispersed in pure water to obtain the test sample. The test sample was then flowed in the planar tensile flow tank of the above-mentioned apparatus, and an image of more than 200 spherical calcium titanate particles moving in the tank was recorded using an objective lens. The average sphericity was calculated from the recorded image and the following formula (1).

[0046] Mean sphericity = (π × HD / PM) 2 …(1)

[0047] In equation (1), HD represents the equivalent circle diameter of the particle, which is obtained by the ratio of the projected area of ​​the object particle to the area of ​​the circle. PM represents the projected circumference of the object particle. For the average sphericity, the "average sphericity" can be calculated first based on the average sphericity (π×HD / PM) of 200 spherical calcium titanate particles, and then the average sphericity can be squared to obtain the mean sphericity.

[0048] The calcium titanate constituting the spherical calcium titanate powder of this embodiment is a composite oxide having a perovskite-type crystal structure represented by the general formula ABO3, specifically CaTiO3 in which Ca occupies A and Ti occupies B. The crystal structure of the spherical calcium titanate powder can be determined by X-ray diffraction.

[0049] In one embodiment, the spherical calcium titanate powder can be surface-treated using a surface treatment agent. By surface-treating with a surface treatment agent, the filling properties of the spherical calcium titanate powder into the resin are easily improved. Examples of surface treatment agents include silane coupling agents and aluminate coupling agents. One or more of these can be used alone or in combination. From the viewpoint of easily reducing polar functional groups on the particle surface, treatment with a silane coupling agent is preferred, and treatment with a vinyl group-containing silane coupling agent such as hexamethyldisilazane (HMDS) or vinyltrimethoxysilane is more preferred.

[0050] In one embodiment, by treating the powder with a surface treatment agent containing hydrophobic functional groups, such as vinylsilane or hexamethyldisilazane (HMDS), it is easy to reduce the polar functional groups on the surface of the particles constituting the spherical calcium titanate powder, thereby easily achieving a lower dielectric loss tangent. Furthermore, the presence or absence of surface treatment on the spherical calcium titanate powder can be confirmed by analyzing the powder using methods such as IR, TG-DTA, or mass spectrometry.

[0051] The spherical calcium titanate powder of this embodiment may also contain other components besides calcium titanate. Examples of other components include calcium carbonate and titanium oxide. These other components may be contained individually or in combination with two or more. When the spherical calcium titanate powder of this embodiment contains other components, their content relative to the total mass of the spherical calcium titanate powder is preferably 1% by mass or less, more preferably 0.5% by mass or less. From the viewpoint of reducing the dielectric loss tangent, the spherical calcium titanate powder preferably does not contain other components.

[0052] In one embodiment, the relative permittivity of the spherical calcium titanate powder related to this embodiment, as measured under the conditions described later, is preferably 50 or more, more preferably 60 or more. Furthermore, the aforementioned relative permittivity may be 70 or more, or 85 or more.

[0053] Similarly, the dielectric loss tangent at 1 GHz, as determined under the conditions described later, is preferably 4.5 × 10⁻⁶. -3 Hereinafter, 3.0 × 10 is preferred. -3 the following.

[0054] As described above, the spherical calcium titanate powder of this embodiment can achieve a higher relative permittivity and a lower dielectric loss tangent than in the past, and therefore can also be used as a ceramic filler for devices in the 10-60 GHz band, for example.

[0055] Typical calcium titanate powders, such as those described in Reference Example 1 below, have a high relative permittivity and a high dielectric loss tangent. Furthermore, such calcium titanate powders exhibit low filling and dispersibility in resins. The inventors of this application have discovered that by spheroidizing calcium titanate powder to improve its dispersibility and filling properties in resins, thereby enhancing its dielectric properties, a low dielectric loss tangent can be achieved while maintaining a high relative permittivity by reducing the interaction between the resin and powder interfaces while adjusting the crystallinity.

[0056] Furthermore, after conducting research on further increasing the relative permittivity of spherical calcium titanate powder, the inventors discovered that, surprisingly, a higher relative permittivity than previously achieved could be obtained by controlling the ratio of D50 to specific surface area (D50 / BET) of the spherical calcium titanate powder within a certain range, while also achieving a low dielectric loss tangent. The powder in this embodiment has a slightly higher D50 relative to BET, thus the particles tend to aggregate to a certain extent, which is presumably easier to achieve: increased crystallinity, a densified morphology like a sintered body, and the ability to exhibit a high relative permittivity.

[0057] [Method for manufacturing spherical calcium titanate powder]

[0058] The spherical calcium titanate powder of this embodiment can be manufactured, for example, by a method including spheroidizing raw calcium titanate powder (step (i)) and heating the spheroidized calcium titanate powder at 600 to 1200°C (step (ii)). Hereinafter, one embodiment of the method for manufacturing spherical calcium titanate powder including steps (i) to (ii) will be described.

[0059] <Process (i)>

[0060] In the manufacturing method of this embodiment, step (i) is a step of spheroidizing the raw material calcium titanate powder. By including step (i), a powder with excellent resin filling properties can be easily obtained. Step (i) is preferably performed by spheroidizing the raw material calcium titanate powder using a powder melting method.

[0061] As for the raw material calcium titanate powder (hereinafter referred to separately as "raw material powder"), from the viewpoint of the average particle size of the spheroidized powder, the ease of processing the powder, or the ease of feeding, the average particle size (D50) is preferably 0.2 to 30 μm, more preferably 1 to 20 μm. In addition, the average sphericity of the raw material powder is not particularly limited.

[0062] There are no particular limitations on the preparation method of the raw material powder. For example, bulk powder of calcium titanate obtained by reacting titanium oxide (TiO2) with calcium carbonate (CaCO3) under high temperature conditions can be used as the raw material powder, or calcium titanate powder prepared by a wet method can be used as the raw material powder. From the viewpoint of ease of acquisition and economy, it is preferable to use the powder prepared by the solid-state method as the raw material powder.

[0063] From the perspective of reducing the dielectric loss tangent and improving the reliability of electronic materials, the preferred raw material powder contains alkali metal elements such as Li, Na, and K, and impurities such as metallic elements such as Fe, as well as Cl. - ,Br -The content of anions is relatively low. Specifically, it is preferred that the combined amount of these impurities and anions in the raw material powder is less than 0.01% by mass.

[0064] As described above, the preferred step (i) is the step of spheroidizing the raw material powder by a powder melting method. The powder melting method refers to a method of spheroidizing the raw material powder by introducing it into a high-temperature condition above its melting point, such as a flame, plasma, electric furnace, or gas furnace. For example, the methods described in Patent Documents 2 and 3 can be used. The melting atmosphere is not particularly limited; from the viewpoint of easily preventing the reduction of the raw material powder, it is desirable to perform spheroidizing in an environment with a high oxygen partial pressure, for example, spheroidizing can be performed in a flame using LPG / O2 gas. Furthermore, the method of feeding the raw material powder is not particularly limited; it can be supplied as dry powder or as a slurry in which the powder is dispersed in water, alcohol, etc.

[0065] In one embodiment, step (i) may also be performed by spherizing the raw material powder to prepare spherical calcium titanate powder with an average sphericity of 0.80 or higher.

[0066] <Process (ii)>

[0067] The manufacturing method described in this embodiment includes: after step (i), heating the spheroidized calcium titanate powder at 600–1200°C (step (ii)). By further heating at 600–1200°C after step (i), fine particles on the surface of the calcium titanate particles are easily removed, and the BET of the resulting powder is easily reduced. As a result, the (D50 / BET) ratio is easily controlled within the range of 10–20.

[0068] The heating temperature in step (ii) is preferably 600–1150°C, more preferably 600–1100°C, even more preferably 800–1000°C, and particularly preferably above 800°C but below 1000°C. By heating the spheroidized calcium titanate powder at such a temperature, the crystallinity can be adjusted, and impurities can be easily reduced. Furthermore, fine particles adhering to the surface of the calcium titanate particles are easily removed. As a result, the specific surface area of ​​the particles is reduced, making it easier to control the (D50 / BET) ratio between 10 and 20, and easily achieving a high relative permittivity and a low dielectric loss tangent while ensuring high reliability.

[0069] As a heating device, an electric furnace, gas furnace, etc., can be used. Furthermore, process (ii) is preferably carried out in the atmosphere. Additionally, the heating time is preferably 1 to 24 hours, more preferably 1 to 12 hours. If the heating time is 1 to 24 hours, productivity tends to be good.

[0070] In one embodiment, it is preferable that after step (ii), crushing that would cause a change of more than 20% in the average particle size (D50) of the resulting spherical calcium titanate powder is not performed. Furthermore, from the viewpoint of easily obtaining spherical calcium titanate powder with a higher relative permittivity, it is preferable to recover the powder without performing crushing after step (ii).

[0071] During process (ii), calcium titanate particles agglomerate together to form aggregates. The manufacturing method described in this embodiment preferably does not involve finely decomposing these aggregates, for example, it does not involve crushing that causes a change of more than 20% in the average particle size (D50) of the spherical calcium titanate powder.

[0072] For example, a crushing process that reduces the D50 of spherical calcium titanate powder by more than 20% can be performed by crushing the powder for more than 30 minutes using an agate mortar, ball mill, vibratory mill, jet mill, or wet jet mill. In the manufacturing method described in this embodiment, by not performing the crushing process described above for more than 30 minutes or by not performing the crushing process at all, it is easy to prevent: the decomposition of the spherical calcium titanate powder, an increase in the proportion of small particles, and an increase in the BET value. As a result, it is easier to control the (D50 / BET) value of the final spherical calcium titanate powder, and it is easier to obtain powder with a higher relative permittivity and a low dielectric loss tangent. The crushing time during the above-described crushing process is more preferably 20 minutes or less.

[0073] Furthermore, in order to obtain spherical calcium titanate powder with a desired average particle size (D50), the manufacturing method of this embodiment may also include a step of classifying the spherical calcium titanate powder. As classification methods, examples include hydrocyclones, air classifiers, etc., in addition to classification using sieves.

[0074] Furthermore, it may also include a process of surface treating the spherical calcium titanate powder with a surface treatment agent, and a cleaning process for reducing impurities (such as the aforementioned anions) in the spherical calcium titanate powder.

[0075] In one embodiment, other spherical calcium titanate powders or powders of other inorganic metals or inorganic oxides with different specific surface areas and average particle sizes (D50) can be incorporated into or mixed with the spherical calcium titanate powder of this embodiment to prepare a mixed powder. By preparing a mixed powder, it is easier to adjust the relative permittivity, dielectric loss tangent, coefficient of thermal expansion, thermal conductivity, filling rate, etc., when mixed in a resin material according to the desired range. In addition, when preparing the mixed powder, other powders can be mixed in within the range of (D50 / BET) of 10 to 20.

[0076] [use]

[0077] When the spherical calcium titanate powder of this embodiment is filled into resin, it can simultaneously achieve a higher relative permittivity and a lower dielectric loss tangent. Therefore, it is suitable for use as a powder for resin filling (a filler material for resin, especially a ceramic filler for high-frequency band sealing materials).

[0078] [Resin Composition]

[0079] The resin composition of this embodiment includes the above-mentioned spherical calcium titanate powder and at least one resin selected from thermoplastic resins and thermosetting resins.

[0080] The content of spherical calcium titanate powder in the resin composition is not particularly limited and can be appropriately adjusted according to the purpose. Even if a large amount of spherical calcium titanate powder of this embodiment is filled into the resin, its processability and workability are unlikely to be reduced. Therefore, the desired dielectric properties can be obtained by adjusting the mixing amount of powder in the resin composition. For example, when used as a substrate material for high-frequency bands or as an insulating material, the mixing amount can be in the range of 1 to 80% by mass relative to the total mass of the resin composition, and more preferably in the range of 10 to 70% by mass.

[0081] <Resin>

[0082] The resin composition of this embodiment includes at least one resin selected from thermoplastic resins and thermosetting resins. More specifically, examples include: polyethylene resin; polypropylene resin; epoxy resin; silicone resin; phenolic resin; melamine resin; urea resin; unsaturated polyester resin; fluororesin; polyamide resins such as polyimide resin, polyamide-imide resin, and polyether-imide resin; polyester resins such as polybutylene terephthalate resin and polyethylene terephthalate resin; polyphenylene sulfide resin; fully aromatic polyester resin; polysulfone resin; liquid crystal polymer resin; polyethersulfone resin; polycarbonate resin; maleimide-modified resin; ABS resin; AAS (acrylonitrile-acrylic rubber-styrene) resin; AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin; hydrocarbon elastomer resin; polyphenylene ether resin; aromatic polyene resin, etc. One of these can be used alone, or two or more can be used in combination.

[0083] Without impairing the effects of this disclosure, the resin composition of this embodiment may also contain curing agents, curing accelerators, release agents, coupling agents, colorants, flame retardants, ion traps, etc.

[0084] <Method for manufacturing resin composition>

[0085] The method for manufacturing the resin composition is not particularly limited, and it can be manufactured by stirring, dissolving, mixing, and dispersing the specified materials. The apparatus for mixing, stirring, and dispersing these mixtures is not particularly limited, and a mortar and pestle equipped with stirring and heating devices, a three-roll mill, a ball mill, a planetary mixer, etc., can be used. Furthermore, these apparatuses can be used in appropriate combinations.

[0086] As described above, the resin composition containing the spherical calcium titanate powder of this embodiment can achieve a high relative permittivity and a low dielectric loss tangent.

[0087] Example

[0088] The present invention will be described in detail below with examples, but the present invention is not limited thereto.

[0089] [Example 1]

[0090] In a flame using LPG / O2 gas, the raw material powder described in Reference Example 1 (calcium titanate powder; manufactured by Kyoritsu Materials Co., Ltd., product name "CT-3") was melted using a powder melting method. The powder had an average sphericity of 0.78, an average particle size (D50) of 3.1 μm, and a specific surface area (BET) of 1.82 m². 2 After spheroidizing (g), the sample was heated at 1000°C for 6 hours. Subsequently, it was recovered without crushing to obtain the spherical calcium titanate powder of Example 1. The average particle size (D50), the proportion of particles with each size, the specific surface area (BET), and the average sphericity of the obtained spherical calcium titanate powder were determined under the following conditions. The results are shown in Table 1.

[0091] (Conditions for determining average particle size)

[0092] The average particle size was measured using a laser diffraction / scattering particle size distribution measuring device (manufactured by Microtrac BEL Co., Ltd., product name "MT 3300 EXII"). First, 80 cm³ of the sample was added to a glass beaker. 3Pure water and 0.1g of spherical calcium titanate powder were dispersed for 1 minute using an ultrasonic homogenizer (manufactured by SMT Co., Ltd., trade name "UH-600S" (homogenizer probe diameter: 20mmφ)). The dispersion of the dispersed spherical calcium titanate powder was added dropwise to a laser diffraction / scattering particle size distribution measuring device using a dropper. The average particle size was measured 30 seconds after the start of the specified addition. The particle size distribution was calculated based on the light intensity distribution data of the diffracted / scattered light from the spherical calcium titanate powder detected by the sensor in the laser diffraction / scattering particle size distribution measuring device. The D50 was calculated based on the cumulative particle size distribution corresponding to 50% of the particle size in the volumetric basis of the measured particle size. Further, the proportion of particles with a particle size of 0.2 times the D50 was calculated according to steps 1 to 3 above.

[0093] In addition, for powders with a D50 of 4 μm or more, the proportion of particles with a diameter of 2.0 μm or less and the proportion of particles with a diameter of 1.0 μm or less are calculated based on the obtained cumulative particle size distribution.

[0094] (Methods for determining specific surface area)

[0095] The BET specific surface area of ​​spherical calcium titanate powder was determined using the following method. First, 4 g of powder was filled into an empty tank and degassed at 300°C. After degassed, the tank filled with spherical calcium titanate powder was placed in an automated specific surface area measuring device (manufactured by Mountech, product name "Macsorb Model 1208") for specific surface area measurement. A He-N2 mixed gas was used for measurement, and the determination was performed at a main flow rate of 25 mL / min using a multi-point method.

[0096] (Method for determining mean sphericity)

[0097] The following steps were performed using a powder imaging analyzer (manufactured by Spectris, product name "FPIA-3000").

[0098] The sample was dispersed in pure water to obtain the test sample. The test sample was then flowed in the planar extension flow tank of the above apparatus, and an image of more than 200 spherical calcium titanate particles moving in the tank was recorded using an objective lens. The average sphericity was calculated from the recorded image and the following formula (1).

[0099] Mean sphericity = (π × HD / PM) 2 …(1)

[0100] In equation (1), HD represents the equivalent circle diameter of the particle, which is obtained by the ratio of the projected area of ​​the object particle to the area of ​​the circle. PM represents the projected circumference of the object particle. For the average sphericity, the "average sphericity" can be calculated first based on the average sphericity (π×HD / PM) of 200 spherical calcium titanate particles, and then the average sphericity can be squared to obtain the result.

[0101] Next, the relative permittivity and dielectric loss tangent of the resin composition containing spherical calcium titanate powder were determined under the following conditions, and the filler equivalent relative permittivity and dielectric loss tangent were calculated.

[0102] (Evaluation of dielectric properties (relative permittivity and dielectric loss tangent))

[0103] The dielectric properties of spherical calcium titanate powder were determined using a powder dielectric constant measuring instrument (manufactured by KEYCOM Co., Ltd., product name "TM Cavity Resonator" (cylindrical cavity resonance method)). The dielectric properties were measured in a PTFE resin bath (cylindrical, volume 1154 cm³). 3 Spherical calcium titanate powder was filled into the device in the range of 2.5 to 3.0 g, and then placed in the device. The resonance peak at 1 GHz was read, and the relative permittivity and dielectric loss tangent were measured.

[0104] [Examples 2-4]

[0105] Spherical calcium titanate powder was prepared according to the manufacturing conditions shown in Table 1. For each example of spherical calcium titanate powder, the average particle size (D50), the proportion of particles having each particle size, the specific surface area (BET), and the average sphericity were measured using the same method as in Example 1. Furthermore, the dielectric properties of the powder were evaluated under the same conditions as in Example 1. The results are shown in Table 1.

[0106] [Examples 5-8]

[0107] The spherical calcium titanate powder prepared in Example 1 was crushed using an agate mortar and pestle under the conditions shown in Table 1 to obtain spherical calcium titanate powder. For each example of spherical calcium titanate powder, the average particle size (D50), the proportion of particles with each size, the specific surface area (BET), and the average sphericity were measured using the same method as in Example 1. Furthermore, the dielectric properties of the powder were evaluated under the same conditions as in Example 1. The results are shown in Table 1.

[0108] [Comparative Examples 1-5]

[0109] The raw material powder was spheroidized according to the conditions shown in Table 1. Subsequently, it was dried at 100°C for 1 hour to obtain spherical calcium titanate powders for each example. For each example of spherical calcium titanate powder, the average particle size (D50), the proportion of particles with each particle size, the specific surface area (BET), and the average sphericity were measured using the same method as in Example 1. Furthermore, the dielectric properties of the powder were evaluated under the same conditions as in Example 1. The results are shown in Table 1.

[0110] [Table 1]

[0111]

[0112] As shown in Table 1, compared to the spherical calcium titanate powders of Comparative Examples 1-5, the spherical calcium titanate powders of Examples 1-8, which satisfy the configuration of this embodiment, have a higher relative permittivity. Furthermore, a comparison between Example 1 and Examples 5-8 shows that a higher relative permittivity and a lower dielectric loss tangent can be achieved without the crushing process. In addition, the spherical calcium titanate powders of Examples 1-8 also have a higher average sphericity and better resin filling properties. Based on the above results, it can be confirmed that the spherical calcium titanate powders of this embodiment have excellent resin filling properties and can achieve a higher relative permittivity and a lower dielectric loss tangent.

[0113] The following is a non-limiting list of exemplary embodiments of this disclosure and combinations thereof.

[0114] [1] A spherical calcium titanate powder having an average particle size (D50: μm) relative to its specific surface area (BET: m²). 2 The ratio of D50 to BET (d50 / g) is 10 to 20.

[0115] [2] The spherical calcium titanate powder according to [1] has an average sphericity of 0.80 or higher.

[0116] [3] The spherical calcium titanate powder according to [1] or [2], wherein the specific surface area (BET) is 0.5 m². 2 / g or less.

[0117] [4] The spherical calcium titanate powder according to any one of [1] to [3], wherein the average particle size (D50) is 0.5 to 15 μm.

[0118] [5] The spherical calcium titanate powder according to any one of [1]-[4] is used for resin filling.

[0119] [6] A resin composition comprising spherical calcium titanate powder as described in any one of [1] to [5] and at least one resin selected from thermoplastic resins and thermosetting resins.

[0120] Industrial availability

[0121] When the spherical calcium titanate powder of this embodiment is filled into resin, it can simultaneously achieve a higher relative permittivity and a lower dielectric loss tangent. Therefore, it has industrial applicability as a powder for resin filling (a filler material for resin, especially a ceramic filler for high-frequency band sealing materials).

Claims

1. A spherical calcium titanate powder, wherein the ratio of average particle size D50 to specific surface area BET, D50 / BET, is 10-20, wherein the average particle size is in μm and the specific surface area is in m². 2 / g.

2. The spherical calcium titanate powder according to claim 1 has an average sphericity of 0.80 or higher.

3. The spherical calcium titanate powder according to claim 1 or 2, wherein, The specific surface area BET is 0.5m². 2 / g or less.

4. The spherical calcium titanate powder according to claim 1 or 2, wherein, The average particle size D50 is 0.5–15 μm.

5. The spherical calcium titanate powder according to claim 1 or 2, which is used as a resin filler.

6. A resin composition comprising the spherical calcium titanate powder of claim 1 or 2 and at least one resin selected from thermoplastic resins and thermosetting resins.

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