Spherical calcium titanate powder and resin composition

Abstract

Provided are: a spherical calcium titanate powder that exhibits superior properties as a filler for a resin, said spherical calcium titanate powder having an elevated relative permittivity, exhibiting little increase in dielectric loss tangent over time, and being capable of maintaining a low dielectric loss tangent over a long period of time; and a resin composition containing the spherical calcium titanate powder.　Specifically provided is a spherical calcium titanate powder wherein the adsorbed moisture content (a) of the powder as measured under the following condition is 450 ppm or less.　[Condition] As a pretreatment, 50 g of the spherical calcium titanate powder is dried for six hours at 100°C. Thereafter, the powder is held in a desiccator at 25°C and 35% RH for three weeks, and then the adsorbed moisture content (a) of the powder is measured at a holding temperature of 200°C by means of the Karl Fischer technique.

Description

Spherical calcium titanate powder and resin composition

[0001] The present disclosure relates to a spherical calcium titanate powder 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 communications devices. However, the application of high-frequency band signals to such devices has also raised the problem of increased transmission loss of circuit signals. Furthermore, as related electronic materials and components have become more highly functional, there has been a demand for further miniaturization of electronic devices and communications 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 can achieve a high dielectric constant and a low dielectric loss tangent.

[0003] To meet such demands, ABO, represented by barium titanate and strontium titanate, has been developed. ３ Powder of perovskite complex oxide, which is a complex oxide represented by the formula (I), has a relatively high dielectric constant and is therefore expected to be a ceramic filler applicable to next-generation electronic devices. Among 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 that make up 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] However, ceramic fillers have the problem that their dielectric loss tangent increases over time, and therefore there is a demand for ceramic fillers that have a small increase in dielectric loss tangent over time and can maintain a low dielectric loss tangent for a longer period than conventional fillers.

[0006] JP 2011-116645 A Japanese Patent No. 4155750 JP 2012-246203 A

[0007] An object of the present disclosure is to provide a spherical calcium titanate powder that is excellent in fillability into resin, has a higher relative dielectric constant, exhibits a small increase in dielectric loss tangent over time, and can maintain a low dielectric loss tangent for a long period of time, and a resin composition containing the same.

[0008] As a result of extensive research, the present inventors have surprisingly found that a spherical calcium titanate powder having an adsorbed moisture content (a) of 450 ppm or less, measured under the following conditions, has a higher dielectric constant, exhibits a small increase in dielectric loss tangent over time, maintains a low dielectric loss tangent for a long period of time, and exhibits good fillability into resin. <Conditions> As a pretreatment, 50 g of spherical calcium titanate powder was dried at 100°C for 6 hours. The powder was then stored in a desiccator at 25°C / 35% RH for 3 weeks, after which the adsorbed moisture content (a) of the powder was measured by the Karl Fischer method at a holding temperature of 200°C.

[0009] According to the present disclosure, it is possible to provide a spherical calcium titanate powder that is excellent in fillability into resin, has a higher relative dielectric constant, exhibits a small increase in dielectric loss tangent over time, and can maintain a low dielectric loss tangent for a long period of time, and a resin composition containing the same.

[0010] 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.

[0011] 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.

[0012] [Spherical calcium titanate powder] The spherical calcium titanate powder according to this embodiment (hereinafter sometimes simply referred to as "powder") is characterized in that the powder has an adsorbed moisture content (a) of 450 ppm or less, as measured under the following conditions. <Conditions> As a pretreatment, 50 g of the spherical calcium titanate powder is dried at 100°C for 6 hours. After storing the powder in a desiccator at 25°C / 35% RH for 3 weeks, the powder's adsorbed moisture content (a) is measured by the Karl Fischer method at a holding temperature of 200°C.

[0013] Powders with an adsorbed water content (a) of 450 ppm or less have a dielectric loss tangent that is less likely to increase over time, allowing them to maintain a low dielectric loss tangent for a long period of time. Such powders can also be stored for longer periods than conventional powders. Furthermore, because the powder according to this embodiment is spherical, it also has good fillability in resin. Furthermore, the powder according to this embodiment can achieve a higher relative dielectric constant. 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. Since the powder according to this embodiment is a calcium titanate powder containing spherical particles, it also has good fillability in resin.

[0014] <Adsorbed Moisture Content> In the present disclosure, under the above conditions, the adsorbed moisture content of the powder immediately after pretreatment, i.e., after drying 50 g of powder at 100°C for 6 hours, is described as "adsorbed moisture content (b)," and the adsorbed moisture content after storage for 3 weeks after pretreatment is described as "adsorbed moisture content (a)." Furthermore, "ppm" in the adsorbed moisture content refers to "ppm by mass." To determine the adsorbed moisture content (a) of the powder according to this embodiment, first, as a pretreatment, 50 g of powder is weighed using a precision balance and then dried at 100°C for 6 hours. Specifically, 50 g of the powder is placed in an aluminum cup and dried at 100°C for 6 hours. Thereafter, 50 g of the pretreated powder is placed in a desiccator at 25°C / 35% RH and stored for 3 weeks. The adsorbed moisture content (a) of the powder after storage is measured by the Karl Fischer method at a holding temperature of 200°C. Specifically, 3 g of the pretreated powder is placed in a Karl Fischer moisture meter (for example, product name "CA-310" manufactured by Nitto Seiko Analytech Co., Ltd.), heated to 200°C, and the amount of moisture released (ppm by mass) is measured. The measurement is carried out in an argon atmosphere. The measurement is continued until the background value falls below 0.2 μg / s.

[0015] The adsorbed moisture content (a) of the powder after three weeks of storage is preferably as low as possible, from the viewpoint of minimizing the increase in dielectric loss tangent over time. In one embodiment, the adsorbed moisture content (a) after storage is preferably less than 450 ppm, preferably 440 ppm or less, more preferably 430 ppm or less, and even more preferably 420 ppm or less. The aforementioned "spherical calcium titanate powder having an adsorbed moisture content (a) of 450 ppm or less" can be easily achieved, for example, by further heat-treating the spherical calcium titanate powder at a specific temperature (preferably 600 to 1200°C) to reduce the absolute value of the amount of moisture adsorbed in the powder.

[0016] A more preferred embodiment is a spherical calcium titanate powder having an adsorbed water content (a) of 450 ppm or less and an adsorbed water content (b) of 320 ppm or less immediately after the pretreatment. If the adsorbed water content (b) measured immediately after the pretreatment is 320 ppm or less and the adsorbed water content (a) after storage is 450 ppm or less, this is preferable because the increase in the dielectric loss tangent over time is smaller. Furthermore, such powders tend to have a higher relative dielectric constant. The adsorbed water content (b) is more preferably less than 320 ppm, even more preferably 310 ppm or less, and particularly preferably 305 ppm or less, because the increase in the dielectric loss tangent over time is smaller and the initial value of the dielectric loss tangent is likely to be lower.

[0017] In one embodiment, the absolute difference between the adsorbed moisture content (b) and the adsorbed moisture content (a) of the powder (|adsorbed moisture content (a) - adsorbed moisture content (b)|) is preferably 150 ppm or less. If the absolute difference between the adsorbed moisture contents (a) and (b) is 150 ppm or less, the powder is more likely to have a smaller increase in dielectric tangent over time. The absolute difference between the adsorbed moisture contents (a) and (b) is preferably 145 ppm or less, more preferably 140 ppm or less, and even more preferably 130 ppm or less.

[0018] <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 is preferably 0.5 to 15 μm. The D50 of the 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.

[0019] In one embodiment, from the viewpoint of easily obtaining a powder with a small increase in dielectric tangent over time and a high relative dielectric constant, D50 of the powder may be 1 to 15 μm, 2 to 15 μm, 3 to 15 μm, 4 to 15 μm, 4 to 10 μm, 4 to 9 μm, 5 to 10 μm, or 5 to 9 μm.

[0020] <Specific surface area (BET)> The specific surface area (BET) of the spherical calcium titanate powder according to this embodiment is 1.0 m ２ / g or less. The specific surface area of ​​the powder can be measured by the BET multipoint method using a fully automatic specific surface area measuring device. Specifically, it can be measured under the following conditions. (Method for Measuring Specific Surface Area) The specific surface area (BET) of spherical calcium titanate powder is measured by the following method. First, 4 g of spherical calcium titanate powder is filled into an empty cell, and degassing treatment is performed in an environment at 300°C. After the degassing treatment, the cell filled with the spherical calcium titanate powder is set in a fully automatic specific surface area measuring device (for example, manufactured by Mountec Co., Ltd., product name "Macsorb Model 1208"), and the specific surface area is measured. The measurement gas is He-N ２ Using a mixed gas, measurements are taken using the multipoint method at a main flow rate of 25 mL / min.

[0021] In one embodiment, the specific surface area (BET) of the powder is 0.9 m ２ / g or less, and ２ The lower limit may be 0.5 m / g or less. ２ That is, the specific surface area (BET) of the powder is preferably 0.5 to 1.0 m ２ / g, and 0.5 to 0.9 m ２ / g, and 0.5 to 0.8 m ２ / g.

[0022] <Average Sphericity> The spherical calcium titanate according to this embodiment preferably has an average sphericity of 0.80 or more. If the average sphericity is 0.80 or more, the fillability and dispersibility in resin are more likely to be improved. 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. 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 (for example, 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 flowed into 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.

[0023] 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.

[0024] 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.

[0025] In one embodiment, treatment with a surface treatment agent having a hydrophobic functional group, such as vinylsilane or hexamethyldisilazane (HMDS), reduces polar functional groups on the particle surfaces constituting the spherical calcium titanate powder, and inhibits the adhesion of physically adsorbed water, thereby reducing the adsorbed water content (a) and (b). This tends to reduce the increase in dielectric loss tangent over time. The presence or absence of surface treatment of the spherical calcium titanate powder can be confirmed by analyzing the powder using, for example, IR, TG-DTA, mass spectrometry, or the like.

[0026] 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 easily achieving a low dielectric loss tangent, it is preferable that the spherical calcium titanate powder does not contain other components.

[0027] In one embodiment, after storing for 3 weeks under the above conditions, the dielectric loss tangent at 1 GHz measured under the conditions described below is preferably less than 0.01, and more preferably less than 8.0 × 10 －３ More preferably, 6.0 x 10 －３The following is more preferable: The powder according to this embodiment has a small increase in dielectric loss tangent over time, and therefore can maintain a low dielectric loss tangent even after being stored under the above conditions for three weeks, for example.

[0028] The dielectric dissipation factor of spherical calcium titanate powder gradually increases even under normal storage conditions, such as room temperature (20-25°C) and 40-50% RH. In spherical calcium titanate powders that do not satisfy the configuration of this embodiment, the dielectric dissipation factor may increase to more than twice the initial value after about four weeks. The present inventors have discovered that the increase in the dielectric dissipation factor of spherical calcium titanate powder over time is due to an increase in the powder's adsorbed moisture content. After further intensive research, the present inventors surprisingly found that spherical calcium titanate powders with an adsorbed moisture content (a) of 450 ppm or less after three weeks of storage under specific conditions show a small increase in the dielectric dissipation factor over time and can maintain a low dielectric dissipation factor for a long period of time. Furthermore, such powders can maintain a low adsorbed moisture content even during long-term storage. Furthermore, such powders can achieve a higher relative dielectric constant.

[0029] 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 also be 70 or more, or 85 or more.

[0030] [Method for producing spherical calcium titanate powder] The spherical calcium titanate powder according to this embodiment may be produced, for example, 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)). Hereinafter, one embodiment of the method for producing spherical calcium titanate powder comprising steps (i) and (ii) will be described.

[0031] <Step (i)> In the production method according to this embodiment, step (i) is a step of spheronizing the raw material calcium titanate powder. By including step (i), it becomes easier to obtain a powder that has excellent fillability into resin. 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] In one embodiment, step (i) may be spheroidizing the raw material powder to prepare a spherical calcium titanate powder having an average sphericity of 0.80 or more.

[0036] <Step (ii)> The production method according to this embodiment includes, after step (i), heating the spheroidized calcium titanate powder at 600 to 1200°C (step (ii)). By further heating at 600 to 1200°C after step (i), the absolute amount of adsorbed moisture on the particle surfaces of calcium titanate is reduced. As a result, powder having an adsorbed moisture content (a) of 450 ppm or less is easily obtained. Note that, from the viewpoint of easily maintaining a high average sphericity of the powder finally obtained, the heating temperature in step (ii) may be 600°C or higher but lower than 1200°C.

[0037] From the viewpoint of easily achieving a lower adsorbed moisture content (a) and / or adsorbed moisture content (b), the heating temperature in step (ii) is preferably 600 to 1000°C. For example, an electric furnace or a gas furnace can be used as the heating device. Step (ii) is preferably carried out in the atmosphere. The heating time is preferably 1 to 24 hours, more preferably 1 to 12 hours. A heating time of 1 to 24 hours tends to improve productivity.

[0038] The present inventors have found that heat treatment of spherical calcium titanate powder, particularly at 600 to 1000°C for 2 to 6 hours, can easily produce powder with an adsorbed moisture content (a) of 450 ppm or less after storage for 3 weeks. The powder obtained by this method is likely to maintain a low dielectric tangent for a long period of time. Furthermore, the powder's relative dielectric constant is likely to be high.

[0039] In one embodiment, the spherical calcium titanate powder obtained after step (ii) may be in the form of agglomerates. Therefore, the method may include crushing such agglomerates. In one embodiment, from the viewpoint of easily obtaining a powder with a higher dielectric constant, it is preferable not to perform crushing after step (ii) that would cause the average particle size (D50) of the obtained powder to vary by 20% or more. It is preferable to recover the powder after step (ii) without performing crushing treatment.

[0040] Examples of the crushing treatment that causes the D50 of the spherical calcium titanate powder to vary by 20% or more include crushing the powder for 30 minutes or more using an agate mortar, ball mill, vibration mill, jet mill, wet jet mill, etc. In the production method according to this embodiment, by not carrying out the crushing treatment for 30 minutes or more, or by not carrying out the crushing treatment at all, it becomes easier to obtain a powder that has a higher relative dielectric constant and can also achieve a low dielectric loss tangent.

[0041] 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.

[0042] 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 forming a mixed powder, the relative permittivity, dielectric loss tangent, thermal expansion coefficient, thermal conductivity, packing ratio, etc., when blended with a resin material can be easily adjusted to desired ranges. The powder according to this embodiment also includes a mixed powder having an adsorbed moisture content (a) of 450 ppm or less.

[0043] In one embodiment, the adsorbed moisture content (c) of the spherical calcium titanate powder immediately after production, as measured by the Karl Fischer method at a holding temperature of 200°C, is preferably 300 ppm or less. The adsorbed moisture content (c) can be measured using a Karl Fischer moisture meter at a holding temperature of 200°C after subjecting 50 g of the spherical calcium titanate powder immediately after production to the above-described pretreatment. In the production method according to this embodiment, step (ii) may involve heating the spherical calcium titanate powder at 600 to 1200°C so that the adsorbed moisture content (c) of the spherical calcium titanate powder measured by the Karl Fischer method at a holding temperature of 200°C is 300 ppm or less. A powder with an adsorbed moisture content (c) of 300 ppm or less can be obtained with a small subsequent increase in adsorbed moisture content, due to factors such as the suppression of reattachment of physically adsorbed water. As a result, a powder with a smaller increase in dielectric tangent over time and a higher relative dielectric constant can be obtained.

[0044] [Applications] As described above, the spherical calcium titanate powder according to this embodiment exhibits a small increase in dielectric loss tangent over time and can maintain a low dielectric loss tangent for a long period of time. Such powder can be suitably used as a filler for resins (a filler for resins, particularly a ceramic filler for high-frequency band sealing materials). In a preferred embodiment, it can also be used as a material (ceramic filler) for 5G communications, such as an antenna-in-package.

[0045] [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.

[0046] <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.

[0047] 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.

[0048] <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.

[0049] As described above, the resin composition according to this embodiment contains spherical calcium titanate powder, which exhibits a small increase in dielectric loss tangent over time, and therefore can maintain a low dielectric loss tangent for a long period of time. The powder also has a high dielectric constant. This powder can also be used, for example, as a resin composition for the 5G communication material described above.

[0050] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following description.

[0051] Example 1 Raw material powder (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 by a powder melting method in a gas flame and then heat-treated at 600°C for 4 hours. The powder was then recovered without being crushed to obtain the spherical calcium titanate powder of Example 1. The resulting spherical calcium titanate powder was measured for adsorbed moisture content (a) and (b), average particle size (D50), specific surface area (BET), and average sphericity under the following conditions. Furthermore, the change over time in the relative permittivity and dielectric loss tangent of the resulting powder was evaluated under the following conditions. The results are shown in Table 1.

[0052] <Measurement Conditions for Adsorbed Moisture Contents (a) and (b)> First, as a pretreatment, 50 g of powder was weighed using a precision balance and then placed in a small dryer and dried at 100°C for 6 hours. The adsorbed moisture content (b) of the powder after the pretreatment was measured using a Karl Fischer moisture meter (manufactured by Nitto Seiko Analytech Co., Ltd., product name "CA-310") at a holding temperature of 200°C. The measurement was carried out in a nitrogen atmosphere. Subsequently, 50 g of the powder was stored in a desiccator at 25°C / 35% RH for 3 weeks. The adsorbed moisture content (a) of the powder after storage was again measured using a Karl Fischer moisture meter (manufactured by Nitto Seiko Analytech Co., Ltd., product name "CA-310") at a holding temperature of 200°C. The measurement was carried out in a nitrogen atmosphere.

[0053] <Measurement conditions for average particle size (D50)> The average particle size was measured using a laser diffraction / scattering particle size distribution analyzer (manufactured by Microtrackbell Co., Ltd., product name "MT3300EXII"). First, 80 cm ３1 g of pure water and 0.1 g of spherical calcium titanate powder were added, and the mixture was dispersed for 1 minute using an ultrasonic homogenizer (manufactured by SMT Corporation, trade 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 data on the light intensity distribution of diffracted / scattered light from the spherical calcium titanate powder detected by a sensor in the laser diffraction / scattering particle size distribution analyzer. D50 was calculated from the particle size corresponding to a cumulative value of 50% in the volume-based cumulative particle size distribution of the particle sizes measured.

[0054] <Measurement conditions for 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.

[0055] <Measuring conditions for 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 then passed through 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.

[0056] Next, the changes over time in 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. <Measurement conditions for dielectric properties (dielectric constant and dielectric loss tangent)> First, the dielectric properties of the spherical calcium titanate powder immediately after production were measured using a powder dielectric constant measuring device (manufactured by Keycom Corporation, product name "TM Cavity Resonator" (cylindrical cavity resonance method)). A PTFE resin cell (cylindrical, volume 1154 cm) was used. ３ The powder was filled with 2.5 to 3.0 g of spherical calcium titanate powder and then set in the device. The resonance peak at 1 GHz was read, and the dielectric constant and dielectric loss tangent were measured. Next, the dielectric loss tangent of the powder stored in a desiccator at 25°C / 35% RH for 3 weeks (3 weeks after production) and the powder stored under the same conditions for 4 weeks (4 weeks after production) were measured under the same conditions.

[0057] [Examples 2 and 3] Spherical calcium titanate powders were obtained under the production conditions shown in Table 1. For each spherical calcium titanate powder, the adsorbed moisture content (a) and (b), average particle size (D50), specific surface area (BET), and average sphericity were measured using the same methods as in Example 1. Furthermore, the changes over time in the relative permittivity and dielectric loss tangent of the obtained powder were evaluated under the same conditions as in Example 1. The results are shown in Table 1.

[0058] [Comparative Examples 1 and 2] 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 a spherical calcium titanate powder of Comparative Example 1. The raw material powder was also spheronized under the conditions shown in Table 1, and then heat-treated to obtain a spherical calcium titanate powder of Comparative Example 2. The resulting spherical calcium titanate powders of each example were measured for adsorbed moisture content (a) and (b), average particle size (D50), specific surface area (BET), and average sphericity in the same manner as in Example 1. Furthermore, the dielectric constant and dielectric loss tangent of the resulting powders were evaluated for changes over time under the same conditions as in Example 1. The results are shown in Table 1.

[0059]

[0060] As shown in Table 1, the spherical calcium titanate powders of Examples 1 to 3, which satisfy the configuration of this embodiment, showed a smaller increase in dielectric loss tangent over time than the spherical calcium titanate powder of Comparative Example 1 even after 3 and 4 weeks of storage, and were able to maintain a low dielectric loss tangent.

[0061] For each example, the powders were pretreated under the aforementioned conditions seven weeks after production, then stored in a desiccator at 25°C / 35% RH for three weeks. The adsorbed moisture content (a) was measured 10 weeks after production. All were found to be 450 ppm or less (Example 1: 414 ppm, Example 2: 316 ppm, Example 3: 185 ppm). For the powders of Comparative Examples 1 and 2, the powders were pretreated under the aforementioned conditions seven weeks after production, then stored in a desiccator at 25°C / 35% RH for three weeks. The adsorbed moisture content (a) was measured, showing a significant increase to 1510 ppm and 1000 ppm, respectively. The dielectric loss tangents of the powders of each example were also measured under the same conditions 10 weeks after production. As a result, as shown in Table 1, the powders of Examples 1 to 3, which had an adsorbed water content (a) of 450 ppm or less, maintained a low dielectric loss tangent even 10 weeks after production. On the other hand, the powders of Comparative Examples 1 and 2 showed an even higher dielectric loss tangent. From the above results, it was confirmed that the spherical calcium titanate powder according to this embodiment has excellent fillability into resin, a higher relative dielectric constant, and a small increase in the dielectric loss tangent over time, and therefore can maintain a low dielectric loss tangent for a long period of time.

[0062] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure is described below. [1] A spherical calcium titanate powder, wherein the adsorbed moisture content (a) of the powder measured under the following conditions is 450 ppm or less. <Conditions> As a pretreatment, 50 g of the spherical calcium titanate powder is dried at 100°C for 6 hours. The powder is then stored in a desiccator at 25°C / 35% RH for 3 weeks, and the adsorbed moisture content (a) of the powder is measured by the Karl Fischer method at a holding temperature of 200°C. [2] The spherical calcium titanate powder according to [1], wherein the adsorbed moisture content (b) of the powder measured by the Karl Fischer method at a holding temperature of 200°C immediately after the pretreatment is 320 ppm or less. [3] The spherical calcium titanate powder according to [1] or [2], wherein the absolute difference between the adsorbed moisture content (b) and the adsorbed moisture content (a) is 150 ppm or less. [4] The spherical calcium titanate powder according to any one of [1] to [3], having an average particle diameter (D50) of 0.5 to 15 μm. [5] The spherical calcium titanate powder according to any one of [1] to [4], having an average sphericity of 0.80 or more. [6] The specific surface area (BET) of 1.0 m ２

[10] The spherical calcium titanate powder according to any one of [1] to [5], having a porosity of 0.01 to 0.01g / g or less. [7] The spherical calcium titanate powder according to any one of [1] to [6], which is for use as a resin filler. [8] A resin composition comprising the spherical calcium titanate powder according to any one of [1] to [7], and at least one resin selected from thermoplastic resins and thermosetting resins. [9] The resin composition according to [8], which is for use as a material for 5G communication.

[0063] The spherical calcium titanate powder according to this embodiment exhibits a small increase in dielectric loss tangent over time and can maintain a low dielectric loss tangent for a long period of time. Such powder has industrial applicability as a resin filler (a filler for resins, particularly a ceramic filler for high-frequency band sealing materials).

Claims

1. A spherical calcium titanate powder, the powder having an adsorbed moisture content (a) of 450 ppm or less as measured under the following conditions: <Conditions> As a pretreatment, 50 g of the spherical calcium titanate powder is dried at 100° C. for 6 hours. After that, it is stored in a desiccator at 25° C. / 35% RH for 3 weeks, and the adsorbed moisture content (a) of the powder is measured at a holding temperature of 200° C. by the Karl Fischer method.

2. The spherical calcium titanate powder according to claim 1, wherein the adsorbed moisture content (b) of the powder measured at a holding temperature of 200°C by the Karl Fischer method immediately after the pretreatment is 320 ppm or less.

3. The spherical calcium titanate powder according to claim 1 or 2, wherein the absolute difference between the adsorbed moisture content (b) and the adsorbed moisture content (a) is 150 ppm or less.

4. The spherical calcium titanate powder according to claim 1 or 2, having an average particle size (D50) of 0.5 to 15 μm.

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

6. Specific surface area (BET) is 1.0 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.

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

8. 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.

9. The resin composition according to claim 8, which is used as a material for 5G communications.

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