Spherical calcium titanate powder and resin composition

Abstract

This disclosure provides spherical calcium titanate powder and a resin composition comprising the same. The spherical calcium titanate powder exhibits excellent resin filling properties, a higher relative dielectric constant, and a smaller time-dependent increase in dielectric loss tangent, enabling it to maintain a low dielectric loss tangent over a long period. The adsorbed moisture content (a) of the spherical calcium titanate powder of this disclosure, as determined under the following conditions, is less than 450 ppm. <Conditions>: As a pretreatment, 50 g of spherical calcium titanate powder is dried at 100°C for 6 hours. Subsequently, after being stored in a desiccator at 25°C / 35%RH for 3 weeks, the adsorbed moisture content (a) of the powder is determined by Karl Fischer method at a holding temperature of 200°C.

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] In response to relevant requirements, perovskite-type composite oxides, primarily represented by ABO3 and represented by barium titanate and strontium titanate, are expected to serve as ceramic fillers for next-generation electronic devices due to their high relative permittivity. Among these, titanium-based composite oxides are being used as electronic materials due to their excellent electrical properties, including dielectric, pyroelectric, and piezoelectric properties. Patent Document 1 describes calcium titanate powder with high crystallinity and excellent electrical properties, as well as a method for its manufacture.

[0005] Ceramic fillers are mostly used in resins. Therefore, 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] In addition, ceramic fillers suffer from a problem of the dielectric loss tangent increasing over time. Therefore, there is a need for a ceramic filler with a smaller increase in the dielectric loss tangent over time and capable of maintaining a low dielectric loss tangent for a longer period than before. 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 subject of this disclosure is to provide spherical calcium titanate powder and a resin composition comprising the spherical calcium titanate powder, wherein the spherical calcium titanate powder has excellent resin filling properties, a higher relative permittivity, and a smaller time-dependent increase in dielectric loss tangent, and can maintain a low dielectric loss tangent for a long period of time.

[0011] After conducting in-depth research, the inventors surprisingly discovered that as long as the adsorbed moisture content (a) of the spherical calcium titanate powder, as measured under the following conditions, is below 450 ppm, it has a higher relative permittivity, and the dielectric loss tangent increases less over time, thus maintaining a low dielectric loss tangent for a long period of time. In addition, it also has good resin filling properties.

[0012] <Conditions>

[0013] As a pretreatment, 50 g of spherical calcium titanate powder was dried at 100 °C for 6 hours. Then, after being stored in a desiccator at 25 °C / 35%RH for 3 weeks, the adsorbed moisture content (a) of the powder was determined by Karl Fischer at a constant temperature of 200 °C.

[0014] According to this disclosure, spherical calcium titanate powder and a resin composition comprising the spherical calcium titanate powder are provided, wherein the spherical calcium titanate powder has excellent resin filling properties, a higher relative permittivity, and a smaller time-dependent increase in dielectric loss tangent, and can maintain a low dielectric loss tangent for a long period of time. Detailed Implementation

[0015] 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 be combined with any other features disclosed in this specification. Furthermore, for a specific parameter, when multiple upper and lower limits are provided, any combination of these upper and lower limits can be used to form a preferred numerical range. Additionally, the lower and / or upper limits of the numerical range described in this disclosure are values ​​within that range, and can also be replaced with the values ​​shown in the embodiments. The expression "X to Y" representing a numerical range means "X or more, Y or less." In other embodiments, there may be instances where a specific description of one embodiment is also applicable to other embodiments, and that description may be omitted.

[0016] 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.

[0017] The various methods disclosed in this specification can be combined with any other features disclosed in this specification.

[0018] In this specification, "powder" refers to an aggregate of multiple particles.

[0019] [Spherical calcium titanate powder]

[0020] The spherical calcium titanate powder (hereinafter, it may also be referred to as "powder") related to this embodiment is characterized in that the adsorbed moisture content (a) of the powder, as measured under the following conditions, is 450 ppm or less.

[0021] <Conditions>

[0022] As a pretreatment, 50 g of spherical calcium titanate powder was dried at 100 °C for 6 hours. Subsequently, after being stored in a desiccator at 25 °C / 35%RH for 3 weeks, the adsorbed moisture content (a) of the powder was determined by Karl Fischer method at a holding temperature of 200 °C.

[0023] Powders with an adsorbed moisture content (a) of 450 ppm or less exhibit a dielectric loss tangent that does not increase over time, thus maintaining a low dielectric loss tangent for extended periods. Such powders can also be stored for a longer time than previously possible. Furthermore, since the powder of this embodiment is spherical, it provides excellent resin filling properties. Moreover, the powder of this embodiment can achieve a higher relative permittivity.

[0024] In this disclosure, "spherical powder" refers to powder in which the individual particles are observed to be spherical or round 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.

[0025] <Moisture content>

[0026] In this disclosure, under the above conditions, the adsorbed moisture content of the powder immediately after pretreatment, i.e., after drying 50g of powder at 100°C for 6 hours, is referred to as "adsorbed moisture content (b)", and the adsorbed moisture content after storage for 3 weeks after pretreatment is referred to as "adsorbed moisture content (a)". Furthermore, "ppm" in adsorbed moisture content refers to "mass ppm".

[0027] To determine the adsorbed moisture content (a) of the powder in this embodiment, firstly, as a pretreatment, 50g of powder was measured using a precision balance and dried at 100°C for 6 hours. Specifically, 50g of powder was placed in an aluminum cup and dried at 100°C for 6 hours. Afterward, 50g of the pretreated powder was added to a desiccator at 25°C / 35%RH and stored for 3 weeks. The adsorbed moisture content (a) of the stored powder was determined using the Karl Fischer method at a maintained temperature of 200°C. Specifically, 3g of the pretreated powder was added to a Karl Fischer moisture meter (e.g., a product named "CA-310" manufactured by Nitto Seiko Analytech Co., Ltd.), heated to 200°C, and the amount of released water (mass ppm) was measured. The measurement was performed under an argon atmosphere. Measurements were taken until the background value was below 0.2 μg / s.

[0028] From the viewpoint of further reducing the time-dependent increase of the dielectric loss tangent, the adsorbed moisture content (a) of the powder after 3 weeks of storage is preferably lower. In one embodiment, the adsorbed moisture content (a) after storage is preferably less than 450 ppm, more preferably less than 440 ppm, more preferably less than 430 ppm, and even more preferably less than 420 ppm.

[0029] Furthermore, the aforementioned "spherical calcium titanate powder with an adsorbed moisture content (a) of 450 ppm or less" can be easily achieved, for example, by further heating 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.

[0030] A more preferred embodiment is a spherical calcium titanate powder with an adsorbed moisture content (a) of 450 ppm or less and an adsorbed moisture content (b) of 320 ppm or less immediately after the pretreatment. When the adsorbed moisture content (b) measured immediately after pretreatment is 320 ppm or less and the adsorbed moisture content (a) after storage is 450 ppm or less, the increase in dielectric loss tangent over time becomes smaller, which is therefore preferable. Furthermore, the relative dielectric constant of such a powder tends to be higher. Considering the smaller increase in dielectric loss tangent over time and the easier reduction of the initial value of the dielectric loss tangent, an adsorbed moisture content (b) of less than 320 ppm is more preferable, further preferably less than 310 ppm, and particularly preferably less than 305 ppm.

[0031] 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. When the absolute difference between the adsorbed moisture content (a) and (b) is 150 ppm or less, it is easier to form a powder with a smaller increase in dielectric loss tangent over time. The absolute difference between the adsorbed moisture content (a) and (b) is preferably 145 ppm or less, more preferably 140 ppm or less, and even more preferably 130 ppm or less.

[0032] <Average particle size (D50)>

[0033] The average particle size (D50) of the spherical calcium titanate powder according to this embodiment (hereinafter, it may also be referred to as "D50") is preferably 0.5 to 15 μm. The D50 of the powder according to this embodiment can be measured under the following conditions.

[0034] (Conditions for determining average particle size)

[0035] The average particle size was measured using a laser diffraction / scattering particle size distribution measuring device (e.g., the product name "MT 3300 EXII" manufactured by MicrotracBEL Co., Ltd.).

[0036] First, fill an 80cm glass beaker with water. 3 0.1 g of spherical calcium titanate powder was dispersed in pure water for 1 minute using an ultrasonic homogenizer (e.g., the trade name "UH-600S" manufactured by SMT Co., Ltd., with a homogenizer tip diameter of 20 mm φ). The dispersion of the 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 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. The 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.

[0037] In one embodiment, from the viewpoint of easily forming powders with a small time-dependent rise in dielectric loss tangent and a relatively high dielectric constant, the D50 of the powder can be 1μm to 15μm, or 2μm to 15μm, or 3μm to 15μm, or 4μm to 15μm, or 4μm to 10μm, or 4μm to 9μm, or 5μm to 10μm, or 5μm to 9μm.

[0038] Specific surface area (BET)

[0039] The specific surface area (BET) of the spherical calcium titanate powder in this embodiment is preferably 1.0 m². 2 / g or less. The specific surface area of ​​the powder can be determined using the BET multi-point method with a fully automated specific surface area measuring device. Specifically, the determination can be performed under the following conditions.

[0040] (Methods for determining specific surface area)

[0041] The specific surface area (BET) of spherical calcium titanate powder was determined by the following method.

[0042] First, 4g 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 25mL / min using a multi-point method.

[0043] In one embodiment, the specific surface area (BET) of the powder can be 0.9 m². 2 Below / g, it can also be 0.8m 2 / g or less. Furthermore, the lower limit is preferably 0.5m. 2 / g or more. That is, the specific surface area (BET) of the powder can be 0.5 to 1.0 m². 2 / g, or 0.5~0.9m 2 / g, and can also be 0.5~0.8m 2 / g.

[0044] Mean sphericity

[0045] The average sphericity of the spherical calcium titanate powder in this embodiment is preferably 0.80 or higher. A 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. Furthermore, the average sphericity of the spherical calcium titanate powder can be measured by the following method.

[0046] (Method for determining mean sphericity)

[0047] The determination is performed using a powder imaging analyzer (e.g., the Spectris "FPIA-3000"), following these steps.

[0048] 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-described 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).

[0049] Mean sphericity = (π × HD / PM) 2 …(1)

[0050] 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.

[0051] 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.

[0052] 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.

[0053] In one embodiment, by treating the powder with a surface treatment agent containing hydrophobic functional groups, such as vinylsilane or hexamethyldisilazane (HMDS), the polar functional groups on the surface of the particles constituting the spherical calcium titanate powder are easily reduced, thereby suppressing the adhesion of physically adsorbed water. Therefore, the adsorbed water content (a) and (b) are easily reduced. Consequently, the time-dependent increase in the dielectric loss tangent is easily reduced. 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.

[0054] 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 easily achieving a low dielectric loss tangent, the spherical calcium titanate powder preferably does not contain other components.

[0055] In one embodiment, after storage under the above conditions for 3 weeks, the dielectric loss tangent at 1 GHz, measured according to the conditions described later, is preferably less than 0.01, more preferably 8.0 × 10⁻⁶. -3 Below, 6.0×10 is even more preferred. -3 The following is an explanation of why the dielectric loss tangent of the powder in this embodiment increases less over time; therefore, even after storage for 3 weeks under the conditions described above, a low dielectric loss tangent can be maintained.

[0056] Even under normal storage conditions, such as room temperature (20-25°C) and 40-50% RH, the dielectric loss tangent of the spherical calcium titanate powder gradually increases. In spherical calcium titanate powders that do not meet the configuration of this embodiment, there are cases where the dielectric loss tangent increases to more than twice its initial value after approximately 4 weeks. The inventors have discovered that the time-dependent increase in the dielectric loss tangent of the spherical calcium titanate powder is based on the increase in the adsorbed moisture content of the powder. Further in-depth research by the inventors revealed a surprising finding: spherical calcium titanate powder with an adsorbed moisture content (a) of 450 ppm or less after 3 weeks of storage under specific conditions exhibits a reduced time-dependent increase in the dielectric loss tangent, and can maintain a low dielectric loss tangent for a long period. Furthermore, such powders can maintain a low adsorbed moisture content even under long-term storage conditions. Furthermore, such powders can also achieve a higher relative permittivity.

[0057] In one embodiment, the relative permittivity of the spherical calcium titanate powder of this embodiment, measured under the conditions described later, is preferably 50 or more at 1 GHz, more preferably 60 or more. Furthermore, the aforementioned relative permittivity may be 70 or more, or 85 or more.

[0058] [Method for manufacturing spherical calcium titanate powder]

[0059] 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.

[0060] <Process (i)>

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] <Process (ii)>

[0068] The manufacturing method described in this embodiment includes heating the spheroidized calcium titanate powder at 600–1200°C after step (i) (step (ii)). By further heating at 600–1200°C after step (i), the absolute amount of adsorbed water on the surface of the calcium titanate particles is reduced. As a result, it is easy to obtain powder with an adsorbed water content (a) of 450 ppm or less. Furthermore, from the viewpoint of easily maintaining a high average sphericity of the final obtained powder, the heating temperature in step (ii) can be 600°C or higher and lower than 1200°C.

[0069] From the viewpoint of easily achieving lower adsorbed moisture content (a) and / or adsorbed moisture content (b), the heating temperature in step (ii) is preferably 600 to 1000°C.

[0070] 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.

[0071] The inventors have discovered that by heating spheroidized calcium titanate powder, particularly at 600–1000°C for 2–6 hours, it is easy to obtain powder with an adsorbed moisture content (a) of less than 450 ppm after storage for 3 weeks. The powder obtained by this method easily maintains a low dielectric loss tangent over a long period. Furthermore, the relative permittivity of the powder is easily increased.

[0072] In one embodiment, after step (ii), the resulting spherical calcium titanate powder forms an agglomerate. Therefore, it may be possible to break up such an agglomerate.

[0073] In one embodiment, from the viewpoint of easily forming powder with a higher relative permittivity, it is preferable not to perform crushing that causes the average particle size (D50) of the resulting powder to change by more than 20% after step (ii), and it is preferable to recover the powder without performing crushing treatment after step (ii).

[0074] For spherical calcium titanate powder, a crushing process that reduces the D50 by 20% or more can be achieved, for example, by crushing the powder for 30 minutes or more 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 30 minutes or more, or by not performing the crushing process at all, it is easy to obtain powder with a higher relative permittivity and also capable of achieving a low dielectric loss tangent.

[0075] 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.

[0076] 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.

[0077] 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 combined 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. The powder of this embodiment also contains mixed powder with an adsorbed moisture content (a) of 450 ppm or less.

[0078] In one embodiment, the adsorbed moisture content (c) of the freshly manufactured spherical calcium titanate powder, as determined by Karl Fischer method at a maintained temperature of 200°C, is preferably 300 ppm or less. Furthermore, the adsorbed moisture content (c) can be measured using a Karl Fischer moisture meter at a maintained temperature of 200°C after performing the aforementioned pretreatment on 50 g of the freshly manufactured spherical calcium titanate powder.

[0079] In the manufacturing method of this embodiment, step (ii) can be performed by heating spherical calcium titanate powder at 600–1200°C, where the adsorbed moisture content (c) of the spherical calcium titanate powder, as determined by the Karl Fischer method at a holding temperature of 200°C, is 300 ppm or less. When the adsorbed moisture content (c) is 300 ppm or less, the re-adsorption of physically adsorbed water can be suppressed, thereby easily obtaining powder with a smaller increase in subsequent adsorbed moisture content. As a result, it is easy to obtain powder with a smaller increase in dielectric loss tangent over time and a relatively higher dielectric constant.

[0080] [use]

[0081] As described above, the spherical calcium titanate powder of this embodiment exhibits a small increase in dielectric loss tangent over time, and can maintain a low dielectric loss tangent for a long period. Such powder is suitable for use as a resin filler (a filler material for resins, especially 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 integrated packaging.

[0082] [Resin Composition]

[0083] 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.

[0084] 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.

[0085] <Resin>

[0086] 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.

[0087] 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.

[0088] <Method for manufacturing resin composition>

[0089] 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.

[0090] As described above, since the resin composition of this embodiment contains spherical calcium titanate powder with a small increase in dielectric loss tangent over time, it can maintain a low dielectric loss tangent for a long period of time. Furthermore, the relative permittivity is also relatively high. Such powder can also be used, for example, in the resin composition for 5G communication materials described above.

[0091] Example

[0092] The present invention will be described in detail below with examples, but the present invention is not limited thereto.

[0093] [Example 1]

[0094] In a flame using LPG / O2 gas, the raw material powder (calcium titanate powder; manufactured by Kyoritsu Materials Co., Ltd., product name "CT-3") was melted to form aggregates with 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. 2After spheroidizing (g), the sample was heated at 600°C for 4 hours. Subsequently, it was recovered without crushing to obtain the spherical calcium titanate powder of Example 1. For the obtained spherical calcium titanate powder, the adsorbed moisture content (a) and (b), average particle size (D50), specific surface area (BET), and average sphericity were determined under the following conditions. Furthermore, the time-dependent changes in the relative permittivity and dielectric loss tangent of the obtained powder were evaluated under the following conditions. The results are shown in Table 1.

[0095] <Determination conditions of adsorbed moisture content (a) and (b)>

[0096] First, as a pretreatment, 50g of powder was weighed using a precision balance and placed in a small dryer, where it was dried at 100°C for 6 hours. The adsorbed moisture content (b) of the pretreated powder was measured using a Karl Fischer moisture meter (product name "CA-310" manufactured by Nitto Seiko Analytech Co., Ltd.) at a maintained temperature of 200°C. The measurement was performed under a nitrogen atmosphere.

[0097] Next, 50g of the above 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 measured again using a Karl Fischer moisture meter (product name "CA-310" manufactured by Nitto Seiko Analytech Co., Ltd.) at a maintained temperature of 200°C. The measurement was performed under a nitrogen atmosphere.

[0098] <Determination conditions for average particle size (D50)>

[0099] The average particle size was measured using a laser diffraction / scattering particle size distribution measuring device (product name "MT 3300 EXII" manufactured by Microtrac BEL Co., Ltd.). First, 80 cm³ of the sample was placed in a glass beaker. 3 Pure water and 0.1 g of spherical calcium titanate powder were dispersed for 1 minute using an ultrasonic homogenizer (SMT Co., Ltd., trade name "UH-600S" (homogenizer probe diameter: 20 mm φ)). The dispersion of the 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 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. The 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.

[0100] <Conditions for determining specific surface area>

[0101] 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 a fully automated specific surface area measuring device (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.

[0102] <Conditions for determining mean sphericity>

[0103] The following steps were performed using a powder imaging analyzer (Spectris product name "FPIA-3000").

[0104] 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-described 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).

[0105] Mean sphericity = (π × HD / PM) 2 …(1)

[0106] 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.

[0107] Next, the time-dependent changes in the relative permittivity and dielectric loss tangent of the resin composition containing spherical calcium titanate powder were measured under the following conditions, and the filler equivalent relative permittivity and dielectric loss tangent were determined.

[0108] <Determination conditions for dielectric properties (relative permittivity and dielectric loss tangent)>

[0109] First, the dielectric properties of freshly manufactured spherical calcium titanate powder were measured using a powder dielectric constant meter (KEYCOM Co., Ltd.'s product name "TM Cavity Resonator" (cylindrical cavity resonance method)). The dielectric properties were then 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.

[0110] Next, the dielectric loss tangent of powder stored in a desiccator at 25°C / 35%RH for 3 weeks (after manufacturing) and powder stored under the same conditions for 4 weeks (after manufacturing) were measured.

[0111] [Examples 2-3]

[0112] Spherical calcium titanate powder was prepared according to the manufacturing conditions shown in Table 1. For each example of spherical calcium titanate powder, the adsorbed moisture content (a) and (b), average particle size (D50), specific surface area (BET), and average sphericity were determined using the same method as in Example 1. Furthermore, the time-dependent changes 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.

[0113] [Comparative Examples 1-2]

[0114] The raw material powder was spheroidized according to the conditions shown in Table 1. Then, it was dried at 100°C for 1 hour to obtain the spherical calcium titanate powder of Comparative Example 1. Furthermore, the raw material powder was spheroidized according to the conditions shown in Table 1 and then subjected to heat treatment to obtain the spherical calcium titanate powder of Comparative Example 2.

[0115] For each of the prepared spherical calcium titanate powders, the adsorbed moisture content (a) and (b), average particle size (D50), specific surface area (BET), and average sphericity were determined using the same method as in Example 1. Furthermore, the time-dependent changes in the relative permittivity and dielectric loss tangent of the obtained powders were evaluated under the same conditions as in Example 1. The results are shown in Table 1.

[0116] [Table 1]

[0117]

[0118] As shown in Table 1, compared to the spherical calcium titanate powder of Comparative Example 1, the spherical calcium titanate powders of Examples 1 to 3 that satisfy the configuration of this embodiment also showed a smaller increase in dielectric loss tangent over time after storage for 3 weeks and 4 weeks, and could also maintain a low dielectric loss tangent.

[0119] For each example of powder, after pretreatment under the above conditions for 7 weeks since manufacturing, the adsorbed moisture content (a) was measured after 3 weeks in a desiccator at 25°C / 35%RH (after 10 weeks since manufacturing). The results were all below 450 ppm (Example 1: 414 ppm, Example 2: 316 ppm, Example 3: 185 ppm). On the other hand, for the powders of Comparative Examples 1 and 2, after pretreatment under the above conditions for 7 weeks since manufacturing, the adsorbed moisture content (a) was measured after 3 weeks in a desiccator at 25°C / 35%RH. The results were 1510 ppm and 1000 ppm, respectively, showing a significant increase in adsorbed moisture content. In addition, the dielectric loss tangent of each example of powder was measured under the same conditions after 10 weeks since manufacturing. The results are shown in Table 1. The powders of Examples 1 to 3, with an adsorbed moisture content (a) of 450 ppm or less, also maintained a low dielectric loss tangent after 10 weeks since manufacturing. On the other hand, the dielectric loss tangent of the powders in Comparative Examples 1 and 2 further increased. Based on the above results, it is confirmed that the spherical calcium titanate powder of this embodiment has excellent resin filling properties, a higher relative permittivity, and a smaller increase in dielectric loss tangent over time, thus enabling it to maintain a low dielectric loss tangent for a long period of time.

[0120] The following is a non-limiting list of exemplary embodiments of this disclosure and combinations thereof.

[0121] [1] A spherical calcium titanate powder, wherein the adsorbed moisture content (a) of the powder, as determined under the following conditions, is less than 450 ppm.

[0122] <Conditions>

[0123] As a pretreatment, 50 g of spherical calcium titanate powder was dried at 100 °C for 6 hours. Subsequently, after being stored in a desiccator at 25 °C / 35%RH for 3 weeks, the adsorbed moisture content (a) of the powder was determined by Karl Fischer method at a maintained temperature of 200 °C.

[0124] [2] According to the spherical calcium titanate powder of [1], the adsorbed moisture content (b) of the powder, which is determined by Karl Fischer method at a holding temperature of 200°C immediately after the pretreatment, is less than 320 ppm.

[0125] [3] According to the spherical calcium titanate powder of [1] or [2], wherein the absolute difference between the adsorbed moisture content (b) and the adsorbed moisture content (a) is less than 150 ppm.

[0126] [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.

[0127] [5] The spherical calcium titanate powder according to any one of [1] to [4], wherein the average sphericity is 0.80 or more.

[0128] [6] The spherical calcium titanate powder according to any one of [1] to [5], wherein the specific surface area (BET) is 1.0 m². 2 / g or less.

[0129] [7] The spherical calcium titanate powder according to any one of [1] to [6] is used for resin filling.

[0130] [8] A resin composition comprising any one of [1] to [7] spherical calcium titanate powder and at least one resin selected from thermoplastic resins and thermosetting resins.

[0131] [9] The resin composition according to [8] is a material for 5G communication.

[0132] Industrial availability

[0133] The spherical calcium titanate powder of this embodiment exhibits a small increase in dielectric loss tangent over time, and can maintain a low dielectric loss tangent for a long period. Such powder is industrially feasible as a resin filler (a filler material for resins, especially a ceramic filler for high-frequency band sealing materials).

Claims

1. A spherical calcium titanate powder, wherein the adsorbed moisture content 'a' of the powder, as determined under the following conditions, is less than 450 ppm. The conditions were as follows: 50g of spherical calcium titanate powder was dried at 100℃ for 6 hours as a pretreatment, and then stored in a desiccator at 25℃ / 35%RH for 3 weeks. The adsorbed moisture content 'a' of the powder was determined by Karl Fischer method at a holding temperature of 200℃.

2. The spherical calcium titanate powder according to claim 1, wherein, After the pretreatment, the adsorbed moisture content b of the powder was determined by Karl Fischer method at a constant temperature of 200°C to be below 320 ppm.

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 less than 150 ppm.

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, wherein, The average sphericity is above 0.

80.

6. The spherical calcium titanate powder according to claim 1 or 2, wherein, The specific surface area (BET) is 1.0 m². 2 / g or less.

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

8. 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.

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

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