Spherical calcium titanate powder, production method therefor, and resin composition

Abstract

Provided are: a spherical calcium titanate powder exhibiting excellent resin-filling properties and with which a higher relative permittivity and low dissipation factor can be achieved; a production method therefor; and a resin composition including said spherical calcium titanate powder.　As calculated from a particle grain-size distribution obtained by a laser diffraction / scattering particle size distribution measurement, the average particle size (D50) of the spherical calcium titanate powder is 0.5-15 μm and the proportion of particles having a particle size 0.2 times the average particle size (D50) is 1.5 vol% or less. The production method for said spherical calcium titanate powder includes spheroidizing a calcium titanate powder serving as the starting material, and heating the spheroidized calcium titanate powder at 600-1200°C.

Description

Spherical calcium titanate powder, its manufacturing method, and resin composition

[0001] The present disclosure relates to a spherical calcium titanate powder, a method for producing the same, and a resin composition.

[0002] In recent years, with the increase in the volume of information communication in the communications field, the use of high-frequency band signals has become widespread in electronic devices and communication devices. However, the application of high-frequency band signals to such devices has also raised the problem of increased transmission loss of circuit signals. In addition, as related electronic materials and components have become more highly functional, there has been a demand for further miniaturization of electronic devices and communication devices. Communication devices can be further miniaturized by increasing the dielectric constant of the antenna material incorporated therein. Therefore, there is a demand for materials (ceramic fillers) that have a high dielectric constant and can achieve a low dielectric loss tangent.

[0003] By the way, perovskite complex oxides are mainly ABO, represented by barium titanate and strontium titanate. ３ This is a complex oxide represented by the formula: Powder of such perovskite complex oxides has a relatively high dielectric constant and is therefore expected to be a ceramic filler applicable to next-generation electronic devices. Of these, titanium-based complex oxides are used as electronic materials because they exhibit excellent electrical properties such as dielectricity, pyroelectricity, and piezoelectricity. Patent Document 1 describes a calcium titanate powder with high crystallinity and excellent electrical properties and a method for producing the same.

[0004] Since ceramic fillers are often used by filling them into resins, it is desirable for their shape to be as spherical as possible in order to improve their fillability and dispersibility in resins, thereby stabilizing their dielectric properties, and also in order to improve their processability and workability.The particles constituting the calcium titanate powder in Patent Document 1 have a square pillar or square pillar-like shape, and no powder containing spherical calcium titanate particles has been studied.

[0005] JP 2011-116645 A Japanese Patent No. 4155750 JP 2012-246203 A

[0006] An object of the present disclosure is to provide a spherical calcium titanate powder that has excellent fillability in resin and can achieve a higher relative dielectric constant and a low dielectric dissipation factor, a method for producing the same, and a resin composition containing the spherical calcium titanate powder.

[0007] As a result of extensive research, the present inventors have found that a spherical calcium titanate powder having an average particle diameter (D50) of 0.5 to 15 μm, calculated from a particle size distribution obtained by laser diffraction / scattering particle size distribution measurement, and having a ratio of particles having a particle diameter 0.2 times the average particle diameter (D50) of 1.5 vol% or less, can be excellently filled into resins and achieve a higher relative dielectric constant and a low dielectric dissipation factor. They also found that such spherical calcium titanate powder can be obtained by a production method including spheroidizing a raw material calcium titanate powder and heating the spherical calcium titanate powder at 600 to 1200°C. Furthermore, they have found that a resin composition containing the spherical calcium titanate powder and at least one resin selected from a thermoplastic resin and a thermosetting resin can be suitably used as a material capable of achieving a high relative dielectric constant and a low dielectric dissipation factor.

[0008] According to the present disclosure, it is possible to provide a spherical calcium titanate powder that has excellent fillability in resin and can achieve a higher relative dielectric constant and a low dielectric dissipation factor, a method for producing the same, and a resin composition containing the spherical calcium titanate powder.

[0009] An embodiment of the present disclosure will be described in detail below. However, the scope of the present disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present disclosure. Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Furthermore, when multiple upper and lower limits are described for a particular parameter, any of these upper and lower limits can be combined to form a suitable numerical range. Furthermore, the lower and / or upper limits of a numerical range described in this disclosure are numerical values ​​within that range and may be replaced with numerical values ​​shown in the examples. The expression "X to Y" indicating a numerical range means "X or more and Y or less." If a specific description described for one embodiment also applies to other embodiments, that description may be omitted in other embodiments.

[0010] Each configuration and combination thereof in each embodiment is merely an example, and addition, omission, substitution, and other modifications of configurations are possible as appropriate within the scope of the gist of this disclosure. The present disclosure is not limited by the embodiments. Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. In this specification, "powder" means an aggregate of multiple particles.

[0011] [Spherical Calcium Titanate Powder] The spherical calcium titanate powder according to this embodiment (hereinafter sometimes simply referred to as "powder") has an average particle diameter (D50) of 0.5 to 15 μm, calculated from the particle size distribution obtained by laser diffraction / scattering particle size distribution measurement, and the proportion of particles having a particle diameter 0.2 times the average particle diameter (D50) is 1.5 vol% or less. The spherical calcium titanate powder according to this embodiment can achieve a higher relative dielectric constant. Furthermore, it can also achieve a low dielectric dissipation factor. In this disclosure, "spherical powder" means that when the powder is observed at 10,000x magnification using a scanning electron microscope, the shape of each particle is observed to be circular or rounded. Because the powder according to this embodiment is a calcium titanate powder containing spherical particles, it also has good fillability into resins.

[0012] <Average particle size (D50)> The average particle size (D50) (hereinafter sometimes referred to as "D50") of the spherical calcium titanate powder according to this embodiment can be measured under the following conditions. (Measuring conditions for average particle size) The average particle size is measured using a laser diffraction / scattering particle size distribution measuring device (for example, manufactured by Microtrackbell Co., Ltd., product name "MT3300EXII"). First, 80 cm ３ 1 g of pure water and 0.1 g of spherical calcium titanate powder are added, and dispersion treatment is carried out for 1 minute using an ultrasonic homogenizer (for example, SMT Corporation, trade name "UH-600S" (homogenizer tip diameter: 20 mmφ)). The dispersion liquid of the dispersed spherical calcium titanate powder is added drop by drop using a dropper to a laser diffraction / scattering particle size distribution analyzer. 30 seconds after the predetermined amount has been added, the average particle size is measured. The particle size distribution is calculated from the data on the light intensity distribution of the diffracted / scattered light of the spherical calcium titanate powder detected by the sensor in the laser diffraction / scattering particle size distribution analyzer. D50 is calculated from the particle size corresponding to a cumulative value of 50% in the volume-based cumulative particle size distribution of the particle sizes to be measured.

[0013] The D50 of the spherical calcium titanate powder according to this embodiment is not particularly limited as long as it is within the range of 0.5 to 15 μm, but from the viewpoint of easily obtaining a powder with a higher relative dielectric constant, it may be 4 to 10 μm, 4 to 9 μm, 5 to 10 μm, 5 to 9 μm, or 6 to 9 μm. Furthermore, from the viewpoint of increasing the filling rate in resin, it may be 1 to 15 μm, 2 to 15 μm, or 3 to 10 μm.

[0014] <Proportion of Particles Having a Particle Diameter 0.2 Times D50> The spherical calcium titanate powder according to this embodiment has a proportion of particles having a particle diameter 0.2 times D50 of 1.5 vol% or less. By having a D50 of 0.5 to 15 μm and a low proportion of particles having a particle diameter 0.2 times D50 (1.5 vol% or less), the spherical calcium titanate powder according to this embodiment can achieve a higher relative dielectric constant. Note that "D50 of 0.5 to 15 μm and a proportion of particles having a particle diameter 0.2 times D50 of 1.5 vol% or less" can be easily achieved, for example, by further heat-treating the spheroidized calcium titanate powder at a specific temperature to remove fine particles adhering to the particle surfaces. Furthermore, this can be more easily achieved by not performing a crushing process that would cause the D50 of the spherical calcium titanate powder to vary by 20% or more after heat treatment, or by recovering the powder without performing a crushing process.

[0015] From the viewpoint of easily obtaining a powder with a higher dielectric constant, the proportion of particles having a particle diameter 0.2 times D50 is preferably 1.0 vol% or less, more preferably 0.8 vol% or less, even more preferably 0.6 vol% or less, and particularly preferably 0.5 vol% or less. The spherical calcium titanate powder according to this embodiment also includes an embodiment in which the proportion of particles having a particle diameter 0.2 times D50 is 0 vol%. In this specification, "0 vol% particles" refers to a situation in which the cumulative value of a specific particle is 0 or the particle is not detected (below the lower measurement limit) in measurement using the laser diffraction / scattering particle size distribution analyzer described above. The proportion of particles having a particle diameter 0.2 times D50 can be determined by the following steps: 1. Measure D50 according to the "Measuring Conditions for Average Particle Size" described above. 2. Calculate the particle diameter by multiplying D50 by 0.2. At this time, the particle size is calculated to one decimal place by rounding off to one decimal place. 3. The proportion of particles having a particle size 0.2 times the D50 obtained in 2 (the particle size to one decimal place obtained by rounding off to one decimal place the particle size calculated by multiplying D50 by 0.2) is determined from the volume-based cumulative particle size distribution.

[0016] In the powder according to this embodiment, the particle size 0.2 times D50 is in the range of 0.1 to 3.0 μm. In one embodiment, the particle size 0.2 times D50 may be 0.4 to 3.0 μm, 0.6 to 2.0 μm, 0.8 to 2.0 μm, or 1.0 to 1.8 μm. In a preferred embodiment, D50 may be 4 to 10 μm, and the proportion of the particle size 0.2 times D50 may be 1.5 vol% or less.

[0017] In one embodiment, the powder may have a D50 of 0.5 to 15 μm, a proportion of particles having a particle diameter 0.2 times the D50 of 1.5 vol% or less, and a proportion of particles having a particle diameter 0.1 times the D50 of 0.5 vol% or less. In this case, the proportion of particles having a particle diameter 0.1 times the D50 of 0.3 vol% or less is more preferable, 0.2 vol% or less is even more preferable, and 0.1 vol% or less is particularly preferable. This embodiment also includes a proportion of particles having a particle diameter 0.1 times the D50 of 0 vol%. In this way, by reducing not only the proportion of particles having a particle diameter 0.2 times the D50 of 0.2 vol%, but also the proportion of particles having a particle diameter 0.1 times the D50 of 0.5 vol%, a higher dielectric constant can be easily achieved.

[0018] <Average Sphericity> The spherical calcium titanate according to this embodiment preferably has an average sphericity of 0.80 or more. An average sphericity of 0.80 or more facilitates improved fillability and dispersibility in resin. The average sphericity of the spherical calcium titanate powder may be 0.85 or more, 0.86 or more, or even 0.87 or more. In one embodiment, the average sphericity of the powder may be in the range of 0.84 or more and less than 0.90. The average sphericity of the spherical calcium titanate powder can be measured by the following method. (Method for Measuring Average Sphericity) Measurement is performed using a powder image analyzer (e.g., Spectris, product name "FPIA-3000") according to the following procedure. A measurement sample is obtained by dispersing a sample in pure water. The measurement sample is then passed through a planar extensional flow cell of the device, and 200 or more spherical calcium titanate particles moving within the cell are recorded as images using an objective lens. The average sphericity is calculated from this recorded image and the following formula (1): Average sphericity = (π×HD / PM) ２ ... (1) In formula (1), HD represents the equivalent circle diameter of the particle and is calculated from the area ratio of the projected area of ​​the target particle to the area of ​​a perfect circle. PM represents the projected perimeter of the target particle. The average sphericity can be calculated by first calculating the "average circularity" from the average value of the circularities (π × HD / PM) of 200 spherical calcium titanate particles, and then squaring this average circularity.

[0019] <Specific surface area (BET)> The specific surface area of ​​the spherical calcium titanate powder according to this embodiment is 0.7 m ２ / g, preferably less than 0.5m ２ It is more preferable that the D50 of the spherical calcium titanate powder and the ratio of particles having a particle diameter 0.2 times the D50 are within the above ranges, and the specific surface area is 0.7 m ２ / g, more preferably less than 0.5m ２ In one embodiment, the specific surface area of ​​the spherical calcium titanate powder is 0.5 m / g or less, since it is easy to achieve a higher relative dielectric constant. ２ / g. In a preferred embodiment, the specific surface area may be in a range where the "D50 / BET" ratio described below is 10 to 20. The specific surface area of ​​the spherical calcium titanate powder can be measured by a BET multipoint method using a fully automatic specific surface area measuring device.

[0020] In one embodiment, the specific surface area (BET: m ２ The ratio (D50 / BET) of the average particle diameter (D50: μm) to the dielectric constant (D50 / g) is preferably 10 to 20, more preferably 10 to 19. From the viewpoint of easily obtaining a powder with a lower dielectric tangent, the (D50 / BET) may be 12 to 19, or may be 14 to 19. A spherical calcium titanate powder with a (D50 / BET) of 10 to 20 is likely to achieve a higher relative dielectric constant.

[0021] The calcium titanate constituting the spherical calcium titanate powder according to this embodiment is represented by the general formula ABO ３ It is a composite oxide having a perovskite-type crystal structure represented by the formula: CaTiO ３ The crystal structure of the spherical calcium titanate powder can be determined by X-ray diffraction measurement.

[0022] In one embodiment, the spherical calcium titanate powder may be surface-treated with a surface treatment agent. Surface treatment with a surface treatment agent tends to improve the fillability of the spherical calcium titanate powder in resin. Examples of surface treatment agents include silane coupling agents and aluminate coupling agents. These may be used alone or in combination of two or more. Among these, treatment with a silane coupling agent is preferred from the viewpoint of easily reducing polar functional groups on the particle surface, and silazanes such as hexamethyldisilazane (HMDS) and silane coupling agents having a vinyl group such as vinyltrimethoxysilane are more preferred.

[0023] In one embodiment, by treating the spherical calcium titanate powder with a surface treatment agent having a hydrophobic functional group, such as vinylsilane or hexamethyldisilazane (HMDS), the polar functional groups on the particle surfaces constituting the powder are easily reduced, making it easier to achieve a lower dielectric tangent. Whether the spherical calcium titanate powder has been surface-treated or not can be confirmed by analyzing the powder using, for example, IR, TG-DTA, mass spectrometry, or the like.

[0024] The spherical calcium titanate powder according to this embodiment may contain other components in addition to calcium titanate. Examples of such other components include calcium carbonate and titanium oxide. These other components may be contained alone or in combination of two or more. When the spherical calcium titanate powder according to this embodiment contains other components, the amount of such other components is preferably 1% by mass or less, and more preferably 0.5% by mass or less, relative to the total mass of the spherical calcium titanate powder. From the viewpoint of reducing the dielectric loss tangent, it is preferable that the spherical calcium titanate powder does not contain other components.

[0025] In one embodiment, the relative dielectric constant at 1 GHz of the spherical calcium titanate powder according to this embodiment, measured under the conditions described below, is preferably 50 or more, more preferably 60 or more. The relative dielectric constant may be 70 or more, or may be 85 or more. Similarly, the dielectric loss tangent at 1 GHz, measured under the conditions described below, is 4.5×10 －３Preferably, the value is 3.0 x 10 or less. －３ The following is more preferred:

[0026] As described above, the spherical calcium titanate powder according to this embodiment can achieve a higher dielectric constant and a lower dielectric dissipation factor than conventional powders, and can therefore be used, for example, as a ceramic filler for devices in the 10 to 60 GHz band. Typical calcium titanate powders have a high dielectric constant but also a high dielectric dissipation factor, as shown in Comparative Example 1 below. Furthermore, typical calcium titanate powders have poor fillability and dispersibility in resins. The present inventors attempted to improve the dielectric properties by spheroidizing calcium titanate powder to improve its dispersibility and fillability in resins. They discovered that by adjusting the crystallinity and reducing the interaction at the interface between the resin and the powder, a low dielectric dissipation factor can be achieved while maintaining a high level of dielectric constant.

[0027] Furthermore, the present inventors have investigated how to further increase the dielectric constant of spherical calcium titanate powder and have surprisingly found that by setting the D50 of the spherical calcium titanate powder within a certain range and further controlling the proportion of particles having a particle diameter 0.2 times D50 to 1.5 vol% or less, it is possible to achieve a higher dielectric constant than conventional ones and at the same time a low dielectric loss tangent. Thus, in the powder according to this embodiment, which has a characteristic particle diameter and particle size distribution, the particles are somewhat coalesced together, which is presumably why it improves crystallinity and makes it easier to achieve a sintered compact-like densified form, thereby enabling the development of a high dielectric constant.

[0028] [Method for producing spherical calcium titanate powder] The spherical calcium titanate powder according to this embodiment can be produced by a method comprising spheronizing a raw material calcium titanate powder (step (i)), and heating the spherical calcium titanate powder at 600 to 1200° C. (step (ii)). One embodiment of the method for producing spherical calcium titanate powder comprising steps (i) and (ii) will be described below.

[0029] <Step (i)> Step (i) is a step of spheronizing the raw material calcium titanate powder. By including step (i), a powder with excellent fillability into resin can be obtained. In step (i), the raw material calcium titanate powder is preferably spheronized by a powder fusion method. The raw material calcium titanate powder (hereinafter simply referred to as "raw material powder") preferably has an average particle size (D50) of 0.2 to 30 μm, more preferably 1 to 20 μm, from the viewpoints of the average particle size of the powder after spheronization, ease of handling of the powder, and ease of feeding. Furthermore, the average sphericity of the raw material powder is not particularly limited.

[0030] The method for preparing the raw material powder is not particularly limited. For example, titanium oxide (TiO ２ ) and calcium carbonate (CaCO ３ The raw material powder may be a bulk powder of calcium titanate obtained by reacting a calcium titanate powder with a calcium stearate powder under high temperature conditions, or a calcium titanate powder prepared by a wet method. From the viewpoints of availability and economy, it is preferable to use a calcium titanate powder prepared by a solid-phase method.

[0031] The raw material powder contains impurities such as alkali metal elements such as Li, Na, and K, and metal elements such as Fe, and Cl, from the viewpoint of reducing the dielectric loss tangent and the reliability of the electronic material. － ,Br － It is preferable that the content of anions such as these is low. Specifically, it is preferable that the total amount of these impurities and anions in the raw material powder is 0.01 mass % or less.

[0032] As described above, step (i) is preferably a step of spheroidizing the raw material powder by a powder melting method. The powder melting method is a method of spheroidizing the raw material powder by introducing it into a high-temperature condition above the melting point, for example, a flame, plasma, electric furnace, gas furnace, etc., and for example, methods such as those described in Patent Documents 2 and 3 can be used. The melting atmosphere is not particularly limited, but from the viewpoint of easily preventing reduction of the raw material powder, it is desirable to spheroidize it in an environment with a high oxygen partial pressure, for example, LPG / O ２The raw material powder can be spheroidized in a flame using a gas. The method of adding the raw material powder is not particularly limited, and the raw material powder may be supplied as a dry powder or as a slurry in which the powder is dispersed in water, alcohol, or the like.

[0033] In one embodiment, step (i) may involve spheroidizing the raw material powder to prepare a spherical calcium titanate powder having an average sphericity of 0.80 or more.

[0034] <Step (ii)> This step includes, after step (i), heating the spheroidized calcium titanate powder at 600 to 1200° C. (step (ii)). The present inventors have found that by further heating at 600 to 1200° C. after step (i), fine particles on the surfaces of the calcium titanate particles are removed, thereby improving the dielectric constant of the resulting powder.

[0035] The heating temperature in step (ii) is preferably 600 to 1150°C, more preferably 600 to 1100°C, even more preferably 800 to 1000°C, and particularly preferably above 800°C and up to 1000°C. Heat-treating the spheroidized calcium titanate powder at such a heating temperature makes it possible to adjust the crystallinity and reduce the amount of impurities. It also facilitates the removal of fine particles adhering to the surfaces of the calcium titanate particles. As a result, the proportion of particles having a particle diameter 0.2 times the D50 is reduced, and a high dielectric constant and a low dielectric loss tangent can be achieved while maintaining high reliability.

[0036] As the heating device, for example, an electric furnace or a gas furnace can be used. Step (ii) is preferably carried out in the atmosphere. 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.

[0037] In one embodiment, after step (ii), it is preferable not to carry out a crushing treatment that would cause the average particle size (D50) of the obtained spherical calcium titanate powder to vary by 20% or more.Furthermore, from the viewpoint of facilitating the production of spherical calcium titanate powder having a higher relative dielectric constant, it is preferable to recover the powder after step (ii) without carrying out a crushing treatment.

[0038] By carrying out step (ii), calcium titanate particles may coalesce to form aggregates. In the production method according to this embodiment, it is preferable not to carry out a process for finely breaking down these aggregates, i.e., a process that would cause the average particle size (D50) of the spherical calcium titanate powder to vary by 20% or more.

[0039] Examples of crushing treatments that result in a 20% or greater change in the D50 of spherical calcium titanate powder include crushing the powder for 30 minutes or longer using an agate mortar, ball mill, vibration mill, jet mill, wet jet mill, etc. In the production method according to this embodiment, by not performing the crushing treatment for 30 minutes or longer, or by not performing the crushing treatment at all, the spherical calcium titanate powder is finely crushed, which makes it easier to prevent an increase in the proportion of small particles (e.g., particles with a particle diameter 0.2 times the D50). As a result, it becomes easier to control the D50 and particle size distribution of the final spherical calcium titanate powder, making it easier to obtain a powder that has a higher dielectric constant and a low dielectric loss tangent. When the crushing treatment is performed, the crushing time is preferably 20 minutes or less.

[0040] The production method according to this embodiment may also include a step of classifying the spherical calcium titanate powder to obtain a spherical calcium titanate powder having a desired average particle size (D50). Examples of classification methods include sieving, liquid cyclone classification, and air classification. Furthermore, the method may also include a step of surface-treating the spherical calcium titanate powder with a surface treatment agent, a washing step to reduce impurities (e.g., the aforementioned anions) in the spherical calcium titanate powder, and the like.

[0041] In one embodiment, the spherical calcium titanate powder according to this embodiment may be blended or mixed with other spherical calcium titanate powders having different specific surface areas or average particle diameters (D50), or other inorganic metal powders, or inorganic oxide powders, to form a mixed powder. By blending the powder in a resin material, the relative permittivity, dielectric loss tangent, thermal expansion coefficient, thermal conductivity, packing ratio, and other properties can be easily adjusted to desired ranges. When forming a mixed powder, the mixed powder is blended with other powders so that the average particle diameter (D50) of the mixed powder is 0.5 to 15 μm, and the proportion of particles having a particle diameter 0.2 times the D50 is 1.5 vol% or less.

[0042] [Uses] The spherical calcium titanate powder according to this embodiment can simultaneously achieve a higher dielectric constant and a low dielectric loss tangent when filled into a resin, and can therefore be suitably used as a powder for filling resins (a filler for resins, particularly a ceramic filler for sealing materials used in high-frequency bands).

[0043] [Resin Composition] The resin composition according to this embodiment contains the spherical calcium titanate powder described above and at least one resin selected from thermoplastic resins and thermosetting resins. The content of the spherical calcium titanate powder in the resin composition is not particularly limited and can be adjusted appropriately depending on the purpose. The spherical calcium titanate powder according to this embodiment does not deteriorate in processability or workability even when highly loaded in a resin, so the amount of powder blended in the resin composition can be adjusted to obtain the desired dielectric properties. For example, when used as a substrate material for high-frequency bands or as an insulating material, the powder may be blended in an amount ranging from 1 to 80% by mass, more preferably from 10 to 70% by mass, based on the total mass of the resin composition.

[0044] <Resin> The resin composition according to this embodiment contains at least one resin selected from thermoplastic resins and thermosetting resins. More specifically, examples of the resin include polyethylene resins; polypropylene resins; epoxy resins; silicone resins; phenolic resins; melamine resins; urea resins; unsaturated polyester resins; fluororesins; polyamide-based resins such as polyimide resins, polyamideimide resins, and polyetherimide resins; polyester-based resins such as polybutylene terephthalate resins and polyethylene terephthalate resins; polyphenylene sulfide resins; wholly aromatic polyester resins; polysulfone resins; liquid crystal polymer resins; polyethersulfone resins; polycarbonate resins; maleimide-modified resins; ABS resins; AAS (acrylonitrile-acrylic rubber-styrene) resins; AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resins; hydrocarbon-based elastomer resins; polyphenylene ether resins; and aromatic polyene-based resins. These may be used alone or in combination of two or more.

[0045] The resin composition according to this embodiment may contain a curing agent, a curing accelerator, a release agent, a coupling agent, a colorant, a flame retardant, an ion scavenger, etc., within the range that does not impair the effects of the present invention.

[0046] <Method for Producing Resin Composition> The method for producing the resin composition is not particularly limited, and the resin composition can be produced by stirring, dissolving, mixing, and dispersing predetermined amounts of each material. The apparatus for mixing, stirring, dispersing, etc., of these mixtures is not particularly limited, and examples that can be used include a mortar and pestle machine equipped with a stirring and heating device, a three-roll mill, a ball mill, a planetary mixer, etc. These apparatuses may also be used in appropriate combination.

[0047] As described above, the resin composition containing the spherical calcium titanate powder according to this embodiment can achieve a high relative dielectric constant and a low dielectric loss tangent.

[0048] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following description.

[0049] Example 1 The raw material powder described in Reference Example 1 (calcium titanate powder; manufactured by Kyoritsu Material Co., Ltd., product name "CT-3", average sphericity of aggregates: 0.78, average particle diameter (D50): 3.1 μm, specific surface area (BET): 1.82 m ２ / g) to LPG / O ２ The powder was spheroidized in a gas flame by a powder fusion method and then heat-treated at 1000°C for 6 hours. The powder was then recovered without being crushed to obtain the spherical calcium titanate powder of Example 1. The average particle size (D50), the proportion of particles having a particle size 0.2 times the D50, the average sphericity, and the specific surface area of ​​the resulting spherical calcium titanate powder were measured under the following conditions. The results are shown in Table 1.

[0050] (Measuring conditions for average particle size) The average particle size was measured using a laser diffraction / scattering particle size distribution measuring device (manufactured by Microtrackbell Co., Ltd., product name "MT3300EXII"). First, 80 cm ３ 1 g of pure water and 0.1 g of spherical calcium titanate powder were added and dispersed for 1 minute using an ultrasonic homogenizer (manufactured by SMT Corporation, product name "UH-600S" (homogenizer tip diameter: 20 mmφ)). The dispersed spherical calcium titanate powder dispersion was added dropwise using a dropper to a laser diffraction / scattering particle size distribution analyzer. 30 seconds after the predetermined amount was added, the average particle size was measured. The particle size distribution was calculated from the light intensity distribution data of the diffracted / scattered light of the spherical calcium titanate powder detected by the sensor in the laser diffraction / scattering particle size distribution analyzer. D50 was calculated from the particle size corresponding to the cumulative value of 50% in the volume-based cumulative particle size distribution of the measured particle size. The proportion of particles having a particle size 0.2 times the D50 was calculated according to steps 1 to 3 above.

[0051] (Method for measuring average sphericity) Measurement was carried out using a powder image analyzer (manufactured by Spectris, product name "FPIA-3000") according to the following procedure. A sample was dispersed in pure water to obtain a measurement sample. The measurement sample was flowed into a planar extensional flow cell of the device, and 200 or more spherical calcium titanate particles moving within the cell were recorded as images using an objective lens. The average sphericity was calculated from this recorded image and the following formula (1): Average sphericity = (π × HD / PM) ２ ... (1) In formula (1), HD represents the equivalent circle diameter of the particle, and is calculated from the area ratio of the projected area of ​​the target particle to the area of ​​a perfect circle. PM represents the projected perimeter of the target particle. The average sphericity was calculated by first calculating the "average circularity" from the average value of the circularity (π × HD / PM) of 200 spherical calcium titanate particles, and then squaring the average circularity.

[0052] (Method for measuring specific surface area) The BET specific surface area of ​​the spherical calcium titanate powder was measured by the following method. First, 4 g of powder was filled into an empty cell, and degassing treatment was performed in an environment of 300°C. After degassing treatment, the cell filled with the spherical calcium titanate powder was set in a fully automatic specific surface area measuring device (manufactured by Mountec Co., Ltd., product name "Macsorb Model 1208"), and the specific surface area was measured. The measurement gas was He—N ２ Measurements were carried out by the multipoint method using a mixed gas at a main flow rate of 25 mL / min.

[0053] Next, the dielectric constant and dielectric loss tangent of the resin composition containing the spherical calcium titanate powder were measured under the following conditions to determine the filler-equivalent dielectric constant and dielectric loss tangent. (Evaluation of Dielectric Properties (Dielectric Constant and Dielectric Loss Tangent)) The dielectric properties of the spherical calcium titanate powder were measured using a powder dielectric constant measuring instrument (manufactured by Keycom Corporation, product name "TM Cavity Resonator" (cylindrical cavity resonance method)). A PTFE resin cell (cylindrical, volume 1154 cm) was used. ３ ) was filled with 2.5 to 3.0 g of spherical calcium titanate powder and set in the apparatus, and then the resonance peak at 1 GHz was read to measure the relative permittivity and dielectric loss tangent.

[0054] [Examples 2 to 4] Spherical calcium titanate powders were obtained under the production conditions shown in Table 1. For each spherical calcium titanate powder, the average particle size (D50), the proportion of particles having a particle size 0.2 times D50, the average sphericity, and the specific surface area were measured using the same methods as in Example 1. The dielectric properties of the powders were also evaluated under the same conditions as in Example 1. The results are shown in Table 1.

[0055] [Examples 5 to 8] The spherical calcium titanate powder obtained in Example 1 was crushed in an agate mortar under the conditions shown in Table 1 to obtain spherical calcium titanate powder. For each spherical calcium titanate powder, the average particle diameter (D50), the proportion of particles having a particle diameter 0.2 times D50, the average sphericity, and the specific surface area were measured in the same manner as in Example 1. The dielectric properties of the powder were also evaluated under the same conditions as in Example 1. The results are shown in Table 1.

[0056] [Comparative Examples 1 to 5] The raw material powder was spheronized under the conditions shown in Table 1. It was then dried at 100°C for 1 hour to obtain spherical calcium titanate powder for each example. The average particle diameter (D50), the proportion of particles having a particle diameter 0.2 times D50, average sphericity, and specific surface area of ​​the spherical calcium titanate powder for each example were measured using the same method as in Example 1. The dielectric properties of the powder were also evaluated under the same conditions as in Example 1. The results are shown in Table 1.

[0057]

[0058] As shown in Table 1, the spherical calcium titanate powders of Examples 1 to 8, which satisfied the configuration of this embodiment, had higher dielectric constants than the spherical calcium titanate powders of Comparative Examples 1 to 5. Furthermore, a comparison of Example 1 with Examples 5 to 8 revealed that a higher dielectric constant and lower dielectric dissipation factor could be achieved without the crushing treatment. Furthermore, the spherical calcium titanate powders of Examples 1 to 8 also had high average sphericity and good resin fillability. Furthermore, a comparison of Reference Example 1 with the Examples confirmed that the production method of this embodiment can control the proportion of particles having a particle diameter 0.2 times the D50 to 1.5 vol% or less. These results confirm that the spherical calcium titanate powder of this embodiment has excellent resin fillability and can achieve a higher dielectric constant and a low dielectric dissipation factor.

[0059] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure are described below. [1] A spherical calcium titanate powder having an average particle size (D50) of 0.5 to 15 μm calculated from a particle size distribution obtained by laser diffraction / scattering particle size distribution measurement, and having a ratio of particles having a particle size 0.2 times the average particle size (D50) of 1.5 vol% or less. [2] The spherical calcium titanate powder according to [1], having an average sphericity of 0.80 or more. [3] A spherical calcium titanate powder having a specific surface area (BET) of 0.5 m ２ [4] The spherical calcium titanate powder according to [1] or [2], wherein the specific surface area (BET: m ２

[0023] The spherical calcium titanate powder according to any one of [1] to [3], wherein the ratio (D50 / BET) of the average particle diameter (D50:μm) to the average particle diameter (D50:μm) (D50 / BET) of the spherical calcium titanate powder (D50 / g) is 10 to 20. [5] The spherical calcium titanate powder according to any one of [1] to [4], which is for use in resin filling. [6] A method for producing the spherical calcium titanate powder according to any one of [1] to [5], comprising: spheronizing a raw material calcium titanate powder; and heating the spheroidized calcium titanate powder at 600 to 1200°C. [7] The method for producing the spherical calcium titanate powder according to [6], wherein, after the heating, no crushing is carried out, which would cause the average particle diameter (D50) of the obtained spherical calcium titanate powder to fluctuate by 20% or more. [8] A method for producing the spherical calcium titanate powder according to [6] or [7], comprising, after the heating, recovering the obtained spherical calcium titanate powder without crushing. [9] A method for producing a spherical calcium titanate powder according to any one of [6] to [8], wherein the spheroidizing step comprises spheroidizing the raw material calcium titanate powder by a powder melting method.

[10] A resin composition comprising the spherical calcium titanate powder according to any one of [1] to [5] and at least one resin selected from the group consisting of a thermoplastic resin and a thermosetting resin.

[0060] The spherical calcium titanate powder according to this embodiment can simultaneously achieve a higher dielectric constant and a lower dielectric loss tangent when filled into a resin, and therefore has industrial applicability as a powder for filling resins (a filler for resins, particularly a ceramic filler for sealing materials in high-frequency bands).

Claims

1. A spherical calcium titanate powder having an average particle diameter (D50) of 0.5 to 15 μm, calculated from a particle size distribution obtained by laser diffraction / scattering particle size distribution measurement, and having a ratio of particles having a particle diameter of 0.2 times the average particle diameter (D50) of 1.5 vol % or less.

2. The spherical calcium titanate powder according to claim 1, having an average sphericity of 0.80 or more.

3. Specific surface area (BET) is 0.5 m ２ 3. The spherical calcium titanate powder according to claim 1 or 2, wherein the average molecular weight of the powder is 1 / g or less.

4. Specific surface area (BET: m ２ 3. The spherical calcium titanate powder according to claim 1, wherein the ratio (D50 / BET) of the average particle diameter (D50:μm) to the average particle diameter (D50:μm) (D50 / g) is 10 to 20.

5. The spherical calcium titanate powder according to claim 1 or 2, which is for use in filling with resin.

6. A method for producing spherical calcium titanate powder according to claim 1 or 2, comprising: spheroidizing a raw material calcium titanate powder; and heating the spheroidized calcium titanate powder at 600 to 1200°C.

7. A method for producing spherical calcium titanate powder as described in claim 6, wherein after the heating, no disintegration is carried out that would cause the average particle size (D50) of the obtained spherical calcium titanate powder to vary by 20% or more.

8. A method for producing spherical calcium titanate powder according to claim 6, comprising recovering the spherical calcium titanate powder obtained after the heating without disintegrating the powder.

9. The method for producing spherical calcium titanate powder according to claim 6, wherein the spheroidizing step includes spheroidizing the raw material calcium titanate powder by a powder melting method.

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

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