KR20230164008A - Powder and method for producing the same, and method for producing the resin composition - Google Patents

Abstract

The present invention relates to a powder containing hollow particles having cavities inside a non-porous outer shell. The average particle diameter (D50) of the powder is 1.0 to 10.0 μm, the content of fine particles with a particle size of less than 1.0 μm is 10% by volume or less, and the content of coarse particles with a particle size of more than 8.0 μm is 20% by volume or less. When the powder is suspended in water, the floating particles are 0.5 to 15.0 mass%, the suspended particles are 0 to 4.0 mass%, and the settled particles are 81.0 to 99.5 mass%.

Description

Powder and method for producing the same, and method for producing the resin composition

The present invention relates to powder suitable as a filler for insulating materials of semiconductors. In particular, it relates to a powder containing hollow particles having cavities inside a non-porous outer shell.

In recent years, high speed and large capacity have been progressing in information communication. Therefore, materials used in communication devices are required to have a low dielectric constant (low Dk) and a low dielectric loss tangent (low Df). For example, printed wiring boards on which semiconductor elements are mounted require insulating materials with a low dielectric constant and low dielectric loss tangent. If the dielectric constant of the insulating material is high, dielectric loss may occur, and if the dielectric loss tangent of the insulating material is high, not only the dielectric loss but also the amount of heat generated may increase.

In order to realize low dielectric constant and low dielectric loss tangent of insulating materials, the development of resin materials, which are the main components of insulating materials, is being carried out. As such resin materials, epoxy resins, polyphenylene ether resins, fluorine resins, etc. have been proposed (for example, refer to Patent Documents 1 to 5).

Fillers are blended into these resin materials for durability (rigidity), heat resistance, etc. As fillers, it is known to use metal oxides such as silica, boron nitride, talc, kaolin, clay, mica, alumina, zirconia, and titania (for example, see Patent Document 3).

WO2009/041137 Japanese Patent Publication No. 2006-516297 Japanese Patent Publication No. 2017-057352 Japanese Patent Publication No. 2001-288227 Japanese Patent Publication No. 2019-172962

Among materials used as fillers, silica is excellent in terms of low dielectric constant and low dielectric loss tangent. However, as data communication capacity and high-speed processing are rapidly progressing, further low dielectric constant and low dielectric loss tangent are required. In addition, the filler is also required not to interfere with the filterability and injectability of the liquid for forming the insulating material in the insulating material manufacturing process.

The present inventors have found that hollow particles that satisfy predetermined conditions including no fine particles and coarse particles can realize low dielectric constant and low dielectric loss tangent of the insulating material, and that the liquid for forming the insulating material in the manufacturing process can be used. We found one that did not interfere with filterability and injectability.

That is, the powder according to the present invention contains hollow particles with cavities inside the non-porous outer shell, has an average particle diameter (D50) of 1.0 to 10.0 μm, and has a content of fine particles with a particle diameter of less than 1.0 μm of 10% by volume or less. , the content of coarse particles exceeding 8.0 μm in particle diameter is 20% by volume or less. When this powder is suspended in water, the floating particles are 0.5 to 15.0 mass%, the suspended particles are 0 to 4.0 mass%, and the settled particles are 81.0 to 99.5 mass%.

In addition, the method for producing powder according to the present invention includes a first step of preparing particles by spray-drying an aqueous silicate alkali solution in a hot air stream, a second step of removing alkali contained in the particles, and calcining the particles from which the alkali has been removed. There is a third process, and between the first process and the third process, a classification process is provided to remove fine particles with a particle size of less than 1.0 μm and coarse particles with a particle size of more than 8.0 μm.

The powder of the present invention enables low dielectric constant and low dielectric loss tangent of insulating materials, and can further improve the transmission speed of semiconductors and reduce transmission loss. In addition, it does not interfere with the filterability and injectability of the liquid for forming the insulating material in the semiconductor manufacturing process, and an excellent insulating material can be stably manufactured.

The powder of the present invention contains hollow particles with cavities inside a non-porous outer shell, and has an average particle diameter of 1.0 to 10.0 μm. Additionally, the content of particles with a particle diameter of less than 1.0 μm (hereinafter referred to as fine particles) is 10 volume% or less, and the content of particles with a particle diameter exceeding 8.0 μm (hereinafter referred to as coarse particles) is 20 volume% or less. When this powder is suspended in water, the floating particles are 0.5 to 15.0 mass%, the suspended particles are 0 to 4.0 mass%, and the settled particles are 81.0 to 99.5 mass%. The powder of the present invention may contain a small amount of solid particles in addition to hollow particles. This is because, when producing hollow particles, there is a possibility that solid particles may also be produced unexpectedly. Solid particles without cavities inside have a large specific gravity, so they are basically considered to be latent among the sedimented particles. It is preferable that 90% by mass or more of the particles contained in the powder are hollow particles.

Here, particles dispersed in water when suspended in water were called suspended particles, and particles with a light specific gravity floating in the upper layer (near the water surface) were called suspended particles. These suspended particles typically have a high porosity. Therefore, as the number of suspended particles mixed in the resin material increases, the dielectric constant and dielectric loss tangent of the resin product decrease.

Additionally, by reducing the content of fine particles (10% by volume or less), the total surface area of all particles decreases. As a result, the amount of SiOH radicals decreases, and the dielectric constant and dielectric loss tangent can be lowered. Additionally, powders containing few fine particles have lower adhesion and improved fluidity. Therefore, handling and dispersibility are also improved. The content of microparticles is preferably 8 volume% or less, more preferably 5 volume% or less, further preferably 3 volume% or less, and most preferably 1 volume% or less.

In addition, by reducing the coarse particles contained in the powder (20% by volume or less), the resin composition containing the powder has good filterability and injectability. Therefore, the resin molded article (resin product) molded from this resin composition has good surface smoothness. Additionally, the amount of suspended particles is controlled to 0.5 to 15.0 mass%. Floating particles usually have a high porosity, and hollow particles with a high porosity generally have a large particle diameter. Therefore, controlling (reducing) the amount of floating particles results in controlling (reducing) the amount of coarse particles. The content of coarse particles is preferably 15 volume% or less, more preferably 10 volume% or less, further preferably 5 volume% or less, and most preferably 1 volume% or less.

Floating particles tend to have low particle strength because the ratio (t/d) between the particle diameter (d) and the outer shell thickness (t) is small. Therefore, there is a risk that the particles may break during the process from mixing the resin material and particles to molding the resin product (i.e., during the manufacturing process). Broken particles not only interfere with low dielectric constant and low dielectric loss tangent, but also deteriorate the fluidity of the resin composition, reduce the uniformity of the resin product (molded article), and generate voids inside the resin product. becomes a factor. However, by controlling the amount of suspended particles, particle breakage can be suppressed.

Additionally, by controlling the amount of suspended particles, the desirable properties of particles with high porosity (e.g., low dielectric constant and low dielectric loss tangent) are secured while the undesirable properties of particles with high porosity (e.g., , the occurrence of cracks) can be suppressed to the point where there is no problem. Among suspended particles, there are particles with a high porosity even in small diameters. These particles are less likely to break than large-diameter particles during the manufacturing process, and as a whole, the undesirable characteristics of particles with a high porosity are suppressed as much as possible. can do. The content of suspended particles is preferably 0.5 to 14.0 mass%, more preferably 0.5 to 13.0 mass%, and still more preferably 0.5 to 12.0 mass%. Moreover, the content of settled particles is preferably 82.0 to 99.5 mass%, more preferably 83.0 to 99.5 mass%, and even more preferably 84.0 to 99.5 mass%.

Additionally, the average particle diameter (D50) of the powder is in the range of 1.0 to 10.0 μm. When the average particle diameter is less than 1.0 μm, many fine particles are contained, resulting in a high specific surface area (high SiOH group content), making it difficult to obtain excellent dielectric properties. Additionally, powders with an average particle diameter exceeding 10 μm are unsuitable for semiconductor use. In the case of semiconductor use, the average particle diameter is preferably 1.5 to 10.0 μm, and more preferably 2.0 to 5.0 μm.

Additionally, the maximum particle diameter (D100) is preferably 50 μm or less, more preferably 40 μm or less, and still more preferably 30 μm or less. The maximum particle diameter (D100) is preferably 10 times or less, and more preferably 8 times or less, the average particle diameter (D50). Usually, it is 2 times or more, and may exceed 5 times as long as it satisfies the requirements of the present invention.

Additionally, the particle size variation coefficient (CV value) of the powder is preferably 60% or less. As a result, when mixed with a resin material, low dielectric constant and low dielectric loss tangent can be stably achieved. Additionally, the surface smoothness of the resin product can be improved. The particle size variation coefficient is more preferably 55% or less, and even more preferably 50% or less.

The porosity of the powder is preferably 10 volume% or more, more preferably 20 volume% or more, and still more preferably 30 volume% or more. Moreover, 70 volume% or less is preferable, 60 volume% or less is more preferable, 50 volume% or less is still more preferable, and 40 volume% or less is most preferable. With this porosity, it is possible to achieve low dielectric constant and low dielectric loss tangent, and the particle strength can be maintained at a predetermined level or higher to effectively suppress particle cracking.

Here, the particles constituting the powder are preferably silica-based particles containing silica as a main component. Therefore, the hollow particles (outer shell) contained in the powder may contain inorganic oxides such as alumina, zirconia, and titania in addition to silica. The content of silica in the particles is preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably contains substantially only silica.

[Resin composition]

A resin composition is prepared by mixing the above-described powder and the resin material. These resin compositions can be used as insulating materials for electronic materials such as semiconductors, specifically, copper-clad laminates, prepregs, build-up films, etc. for forming printed wiring boards (including rigid substrates and flexible substrates). Additionally, it can be used for semiconductor package-related materials such as mold resin, mold underfill, and underfill, and adhesives for flexible substrates.

As the resin, a curable resin generally used in electronic materials such as semiconductors can be used. Although a photocurable resin may be used, a thermosetting resin is preferable. Examples of the curable resin include epoxy resin, polyphenylene ether resin, fluorine resin, polyimide resin, bismaleimide resin, acrylic resin, methacrylic resin, silicone resin, BT resin, and cyanate resin. You can. In addition, as epoxy resins, bisphenol-type epoxy resins, novolak-type epoxy resins, triphenol alkane-type epoxy resins, epoxy resins with a biphenyl skeleton, epoxy resins with a naphthalene skeleton, dicyclopentadienephenol novolak resins, and phenol Examples include aralkyl-type epoxy resin, glycidyl ester-type epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, and halogenated epoxy resin. These resins may be used individually or may be used in mixture of two or more types.

The resin composition preferably contains powder A and curable resin B in a mass ratio (A/B) of 10/100 to 95/100. As a result, the function as a filler can be sufficiently exercised while maintaining the characteristics of the resin composition, such as fluidity. The mass ratio (A/B) is more preferably 30/100 to 80/100.

Additionally, the resin composition preferably contains a curing agent such as a phenol compound, amine compound, or acid anhydride. When using an epoxy resin for a curable resin, a resin having two or more phenolic hydroxyl groups in one molecule (bisphenol-type resin, novolak resin, triphenol alkane-type resin, resol-type phenol resin, phenol aralkyl resin, phenol resins such as biphenyl-type phenol resins, naphthalene-type phenol resins, and cyclopentadiene-type phenol resins) and acid anhydrides such as methylhexahydrophthalic acid, methyltetrahydrophthalic acid, and methylnadic anhydride. Various additives (coloring agent, stress reliever, antifoaming agent, leveling agent, coupling agent, flame retardant, curing accelerator, etc.) may be added to the resin composition as needed.

The method for producing the resin composition can be a conventionally known method. For example, curable resin, powder, curing agent, additives, etc. are mixed and kneaded using a roll mill or the like. The obtained resin composition is applied to the base and cured by heat, ultraviolet rays, etc.

[Powder manufacturing method]

The method for producing powder of the present invention includes a first step of preparing particles by spray-drying an aqueous silicate alkali solution in a hot air stream, a second step of removing alkali contained in the prepared particles, and baking the alkali-removed particles. There is a third process, and a process (classification process) is provided between the first process and the third process to classify the particles and remove fine particles with a particle size of less than 1.0 μm and coarse particles with a particle size of more than 8.0 μm. Additionally, between each process, other processes such as a drying process may be provided. Through this process, the powder described above can be obtained.

Generally, when producing particles by firing, it is considered desirable to perform classification treatment after firing in order to adjust the particle diameter. However, here, classification treatment is performed before firing. When the firing process is performed without performing classification treatment, the product is fired with the fine particles to be removed present, and the fine particles are sintered with other particles. Therefore, even if classification treatment is performed thereafter, fine particles cannot be removed. Additionally, coarse particles with high porosity that need to be removed also exist. Since these coarse particles with a high porosity are easy to break, there is a risk of breaking them due to the stress of shrinkage due to heating. Because the fragments generated by cracking are dense silica without voids, they interfere with low dielectric constant and low dielectric loss tangent. These problems can be avoided if classification treatment is performed before firing. Therefore, lowering the dielectric constant and lowering the dielectric loss tangent of the particles can be realized more reliably, and particles corresponding to the increased speed of data communication can be obtained. In addition, after baking, classification processing may be performed again. Hereinafter, each process will be described in detail.

(1st process)

In this process, an aqueous silicate alkali solution is spray-dried in a hot air stream to granulate silica-based particles. In addition, although this process is performed to obtain hollow particles, it is difficult to turn all particles into hollow particles, and the granulated silica-based particles may eventually contain solid particles. In this case, the powder obtained through the process described later also contains solid particles. However, if the powder has the above-mentioned properties, the expected effect can be obtained even if solid particles are contained.

The molar ratio (SiO ₂ /M ₂ O) of SiO ₂ and M ₂ O (M is an alkali metal) of alkali silicate is preferably 1 to 5, and more preferably 2 to 4. When this molar ratio is less than 1, the amount of alkali is too large, so it is difficult to sufficiently remove it even if acid washing is performed in the alkali removal step. Additionally, because the deliquescent nature of the spray-dried product increases, it is difficult to obtain the desired hollow particles. When this molar ratio exceeds 5, the solubility of alkali silicate decreases, making it difficult to prepare an aqueous solution. Even if an aqueous solution can be prepared, there are cases where hollow particles cannot be formed by spray drying.

The concentration of SiO ₂ in the aqueous silicic acid alkali solution is preferably 1 to 30 mass%, and more preferably 5 to 28 mass%. Manufacturing is possible even at less than 1% by mass, but productivity is significantly reduced. If it exceeds 30% by mass, the stability as an aqueous silicate alkali solution decreases significantly, becomes highly viscous, and spray drying may not be possible. Even if spray drying is possible, the particle size distribution, outer shell thickness, etc. become very non-uniform, and the uses of the obtained particles may be limited. As an alkali silicate, sodium silicate and potassium silicate, which are soluble in water, can be used. Sodium silicate is preferred.

As a spray drying method, for example, conventionally known methods such as the rotating disk method, the pressure nozzle method, and the two-fluid nozzle method can be adopted. Here, the two-fluid nozzle method is suitable.

In spray drying, the inlet temperature in the spray dryer is preferably 300 to 600°C, and more preferably 350 to 550°C. Moreover, the outlet temperature is preferably 120 to 300°C, and more preferably 130 to 250°C. By setting this temperature, hollow particles can be obtained stably.

(2nd process)

Next, the alkali contained in the particles granulated in the first process is removed. A method of removing it by adding acid to neutralize it is suitable. A treatment in which the particles are immersed in a solution of acid is preferred. At this time, the molar ratio (Ma/Msp) of the number of moles of M ₂ O in the particles (Msp) and the number of moles of acid (Ma) is preferably 0.6 to 4.7, and more preferably 1 to 4.5. When this molar ratio is less than 0.6, the amount of acid is too small compared to M ₂ O. Therefore, the silica skeletonization of silicic acid, which is thought to occur with the removal of alkali, does not proceed, and the particles may partially dissolve, or the dissolved alkali silicic acid may gel. Even if the molar ratio exceeds 4.7, silica skeletonization does not proceed further, and the acid is excessive and is not economical.

Additionally, it is preferable to immerse the particles in an aqueous acid solution so that the concentration of the particles is 1 to 30% by mass in terms of SiO ₂ . If it is less than 1% by mass, there is no problem with alkali removal or cleanability, but manufacturing efficiency decreases. If it exceeds 30% by mass, the concentration may be too thick and alkali removal and cleaning efficiency may decrease. 5 to 25 mass% is more preferable.

The conditions for immersion in the acid aqueous solution are not particularly limited as long as the alkali can be removed to the desired amount. Usually, the treatment temperature is 5 to 100°C and the treatment time is 0.5 to 24 hours. After the immersion treatment, it is preferable to wash by a conventionally known method. For example, filtration and cleaning with pure water. Additionally, if necessary, the acid treatment and washing may be repeated.

The remaining amount (mass ratio) of alkali (M) after alkali removal is preferably 300 ppm or less, more preferably 200 ppm or less, and still more preferably 100 ppm or less. By sufficiently removing alkali in this process, particles can be prevented from coalescing in subsequent processes, thereby preventing sintered particles from occurring in the firing process. Additionally, it is known that the remaining amount (content) of alkali affects dielectric properties. By sufficiently removing alkali in this process, particles that enable low dielectric constant and low dielectric loss tangent can be obtained even when an aqueous silicate alkali solution is used as the raw material.

Additionally, the alkali amount of the final product (particles constituting the powder) is preferably within the above-described range, and is usually equal to the alkali amount after the alkali removal process.

The remaining amount of alkali can be measured using an atomic absorption spectrophotometer using a sample obtained by dissolving powder with acid. When sodium silicate is used, Na is measured, and when potassium silicate is used, K is measured. Specifically, it is explained in examples.

As the acid used in this process, inorganic acids (hydrochloric acid, nitric acid, sulfuric acid, etc.) and organic acids (acetic acid, tartaric acid, malic acid, etc.) can be used. Inorganic acids are suitably used, and sulfuric acid, which has a large valence, is particularly preferable.

(Third process)

Next, the particles after the alkali removal treatment are fired. The firing temperature is preferably 600 to 1200°C, and more preferably 900 to 1100°C. When the firing temperature is less than 600°C, the remaining amount of SiOH groups is large, and the dielectric loss tangent of the particles increases. Therefore, even if it is mixed with resin, it is difficult to obtain the dielectric loss tangent reduction effect. When the sintering temperature exceeds 1200°C, the particles are likely to sinter with each other, so particles of odd shapes or coarse particles are likely to be generated. This causes the filterability and injectability of the resin composition to decrease.

(Classification process)

By performing classification treatment between the first step and the third step, fine particles and coarse particles are removed. When classification treatment is performed before alkali removal, it is necessary to carry out classification treatment immediately after assembly in order to prevent hollow particles from absorbing moisture (deliquescence) and agglomerating and coalescing. In addition, when classification treatment is performed before firing, classification treatment may be performed continuously after alkali removal treatment.

Through the classification process, the amount of fine particles is reduced to 10% by volume or less. It is preferably 8 volume% or less, more preferably 5 volume% or less, even more preferably 3 volume% or less, and most preferably 1 volume% or less. Additionally, the amount of coarse particles is reduced to 20% by volume or less. It is preferably 15 volume% or less, more preferably 10 volume% or less, even more preferably 5 volume% or less, and most preferably 1 volume% or less. Through this classification process, the proportion of suspended particles present in the powder can be controlled to a predetermined range. Additionally, usually, the content of fine particles or coarse particles in the final product does not change significantly from the content after the classification process.

The classification treatment in this classification process refers to particle size classification where the powder is divided by particle size for the purpose of matching the particle size of the powder. An example of this particle size classification operation is fluid classification, and fluid classification can be classified into dry classification and wet classification.

Classifiers used in dry classification can, in principle, be broadly divided into gravity classifiers, inertial classifiers, and centrifugal classifiers. By using an inertial classifier or centrifugal classifier, more precise classification is possible. It is a classifier that can precisely classify even particles that are light and difficult to apply centrifugal force, and includes an elbow jet manufactured by Nittetsu Kogyo Corporation, an SG separator manufactured by Japan's 3M Corporation, an Aerofine Classifier manufactured by Nisshin Engineering Corporation, and a micro spindle manufactured by Nippon Pneumatic Corporation. You can. Among these, elbow jet and Aerofine Clashifier are preferred.

In principle, classifiers used for wet classification can be broadly divided into gravity classifiers and centrifugal classifiers. By using a centrifugal classifier, more precise classification is possible. Classifiers that are lightweight and can precisely classify even particles to which centrifugal force is difficult to apply include the Hydro Cyclone manufactured by Nippon Kagaku Kikai Kogyo, the Sparklone manufactured by Murata Kagaku Kogyo, and the Eye Clashifier manufactured by Satake Kagaku Kikai Kogyo. . Among these, Eye Clashifier is preferable. According to wet classification, when removing fine particles, coarse particles with a small specific gravity can be removed together, thereby improving classification efficiency.

The removal of fine particles and coarse particles may be performed simultaneously or separately. When performed separately, it does not matter which of the removal of fine particles or removal of coarse particles is performed first. In addition, each treatment of removal of fine particles and removal of coarse particles may be performed in multiple steps.

Additionally, during the manufacturing process, a drying treatment process may be provided as appropriate. The drying treatment can be provided between the alkali removal treatment and the classification treatment, between the classification treatment and baking, both, or between the alkali removal treatment and baking. Multiple sessions may be provided as needed. Additionally, drying treatment may be performed before firing, and classification treatment may be performed between drying treatment and baking. In order to further enjoy the effect of the present invention, it is preferable to perform classification treatment and baking after drying treatment. As a drying treatment, heat drying is suitable. The drying temperature is preferably 50 to 400°C, and more preferably 50 to 200°C. Specifically, examples include a method of drying at a low temperature of about 50 to 200°C over time, a method of drying by slowly raising the temperature, or a method of drying by changing the temperature in several stages.

In addition, it is preferable to provide a sieving treatment to separate the particle lumps at least once after drying and after firing. In addition, particle agglomeration refers to, for example, particle diameter exceeding 50 ㎛, and a sieve with an eye size (mesh number) to remove such particle agglomeration is appropriately used.

Example

Hereinafter, embodiments of the present invention will be described in detail.

[Example 1]

Using 30,000 g of water glass aqueous solution (SiO ₂ /Na ₂ O molar ratio 3.2, SiO ₂ concentration 24 mass%), air was supplied to one side of the two-fluid nozzle at a flow rate of 0.62 kg/hr and 31,800 L/hr (air) to the other nozzle. At a flow rate of /liquid volume ratio of 63600), hollow particles were granulated by spraying with hot air at an inlet temperature of 400°C. Here, the outlet temperature was 150°C (first process). In the first process, there is a possibility that a small amount of solid particles may also be assembled, but there is no need to remove the solid particles and proceed to the next process.

Subsequently, 5,000 g of these hollow particles (i.e., particles granulated in the first step) were immersed in 32,000 g of an aqueous sulfuric acid solution with a concentration of 10% by mass, and stirred for 15 hours. The solid content (SiO ₂ ) concentration is 10.2 mass%. Additionally, since sulfuric acid is a divalent acid, the ratio (Ma/Msp) of the number of moles of acid (Ma) and the number of moles of alkali (Na ₂ O) (Msp) is 3.3. The temperature of the dispersion was 35°C and pH was 3.0. After the immersion treatment, filtration cleaning was performed with pure water (second step).

Subsequently, drying was performed in a dryer at 120°C for 24 hours. After drying, it was pulverized and passed through a sieve with an eye size of 75 μm to remove particle agglomerates.

Subsequently, dry centrifugal classification was performed using a cyclone manufactured by the company, with the flow rate of the powder transport line set to 5 m/s (first classification process). Particles that passed through the cyclone without being collected, that is, particles from which coarse particles were removed, were recovered using a bag filter. After that, dry inertial classification was performed using an elbow jet (EJ-15) manufactured by Nittetsu Kogyo Co., Ltd. (second classification process). When classified using this device, it can be divided into three types of particles: F powder (fine powder), M powder (fine powder), and G powder (coarse powder). At this time, the F edge distance was adjusted so that the fine particles contained in the F powder (fine powder) were 1% by volume or less. Portion F was recovered and used in the subsequent process.

The recovered particles were heat-treated at 1000°C for 10 hours to obtain a powder containing hollow particles (third process). Additionally, after firing, particle lumps were removed using a sieve with an eye size of 150 μm.

The obtained powder was added to the liquid epoxy resin "ZX-1059, manufactured by Nittetsu Chemical & Materials," along with the liquid acid anhydride "Likacid MH700, manufactured by Shin-Nippon Rika Co., Ltd." and the imidazole-based epoxy resin hardener, "2PHZ-PW, manufactured by Shikoku Chemicals Co., Ltd." It was combined. Here, “ZX-1059” was 100 parts by mass, “Ricacid MH700” was 86 parts by mass, and “2PHZ-PW” was 1 part by mass, and the mixture was mixed so that the powder ratio of the blend was 35% by volume. This blend was pre-kneaded with a planetary mill and then kneaded with three rolls to obtain a paste (resin composition). This paste was cured by heating at 170°C for 2 hours to obtain a plate-shaped resin molded product (resin product) measuring 50 mm x 50 mm x 1 mm.

The physical properties of the powder and resin molding obtained as described above were measured and evaluated as follows. The results are shown in Table 1 along with the preparation conditions. The same procedure was performed in other examples and comparative examples.

(1) Particle diameter, particle amount and particle size variation coefficient (CV value)

The particle size distribution of the powder was measured in a dry manner using a particle size analyzer (Laser Micron Sizer LMS-3000 manufactured by Seishin Kigyo Co., Ltd.). From the measurement results, the volume average particle diameter (D43), average particle diameter (D50), and maximum particle diameter (D100) were obtained. Furthermore, this particle size distribution was analyzed, and the volume ratio of coarse particles exceeding 8.0 μm and fine particles less than 1.0 μm were calculated, respectively, to be the coarse particle amount and the fine particle amount.

The particle size variation coefficient (CV value) was obtained from the following formula. The particle diameter (Di) of each particle was measured by a dry laser diffraction/scattering method.

CV value (%) = (standard deviation (τ) / volume average particle diameter (D43)) × 100

Standard deviation (τ)=(ΣXi(Di-D43)^2/ΣXi)^(1/2)

(2) Alkali remaining amount

The powder was pretreated with sulfuric acid and hydrofluoric acid, then dissolved in hydrochloric acid, and the amount of alkali was measured by atomic absorption spectrometry using an atomic absorption spectrophotometer (Z-2310 manufactured by Hitachi). In Example 1, the amount of Na was measured.

(3) Particle density and porosity

The average density (particle density) of particles contained in the powder was measured by the gas pycnometer method using Ultrapyc 1200e manufactured by Quantachrome Instruments. The gas used was nitrogen gas.

From this particle density, the porosity (%) was calculated using the formula “[2.2-(particle density)]/2.2×100”. Assuming that the powder is composed of silica particles, a silica density of 2.2 g/cm3 was used in this equation.

(4) Dielectric constant (Dk) and dielectric loss tangent (Df) of powder

The dielectric constant (Dk) and dielectric loss tangent (Df) were measured by the cavity perturbation method using a network analyzer (MS46122B, manufactured by Anritsu) and a cavity resonator (1 GHz). Measurement was made based on ASTMD2520 (JIS C2565).

(5) Ratio of suspended particles, suspended particles and settled particles when suspended in water

First, the powder and water were mixed to 5% by mass, and ultrasonic treatment was performed for 10 minutes. After the obtained dispersion was left standing at 25°C for 24 hours, floating particles, suspended particles, and settled particles were each collected. Subsequently, each particle was dried at 105°C for 24 hours, then weighed, and the ratio was calculated.

(6) Filterability of resin composition

A filter (SHP type: 30 μm) manufactured by Loki Techno was used, and evaluation was made based on the amount of liquid passing per unit area until the filter was clogged.

The evaluation criteria are as follows.

◎: ≥1g/㎠

○: More than 0.5g/㎠ and less than 1.0g/㎠

△: More than 0.3g/㎠ and less than 0.5g/㎠

×: <0.3g/㎠

(7) Injectability of resin composition

The resin composition was injected between glass plates with a gap of 20 μm, and the time required to fill 25 mm was evaluated.

The evaluation criteria are as follows.

◎: Within 200 seconds

○: Exceeding 200 seconds and within 400 seconds

△: Exceeding 400 seconds and within 600 seconds

×: More than 600 seconds

(8) Dielectric constant (Dk) and dielectric loss tangent (Df) of resin moldings

The dielectric constant (Dk) and dielectric loss tangent (Df) of a plate-shaped molded body (resin molded product) measuring 50 mm . It was compared with a resin molded product containing no powder (filler) using the following formula, and evaluated based on the following criteria.

Reduction rate (%) of dielectric constant (Dk) = (dielectric constant without powder mixing - dielectric constant with powder mixing) / dielectric constant without powder mixing × 100

○: Reduction rate>0

△: Reduction rate = 0

×: Reduction rate<0

Reduction rate (%) of dielectric loss tangent (Df) = (dielectric loss tangent without powder mixing - dielectric loss tangent with powder mixing) / dielectric loss tangent without powder mixing × 100

◎: Reduction rate of 50% or more

○: Reduction rate 30% or more but less than 50%

△: Reduction rate 20% or more but less than 30%

×: Reduction rate less than 20%

[Example 2]

In the second classification process, dry centrifugal (semi-free vortex) classification was performed using an Aerofine Classifier manufactured by Nissin Engineering. The angle of the blade, etc. was adjusted so that the fine particles contained in the particles recovered by classification were 1% by volume or less. Other than that, it was the same as Example 1.

[Example 3]

In the second classification process, wet centrifugal classification was performed using an i-classifier manufactured by Satake Kagaku Kikai Kogyo Co., Ltd. The recovered particles were classified so that the fine particles contained in them were 1% by volume or less, and the coarse particles contained were 1% by volume or less. Other than that, it was the same as Example 1.

[Example 4]

In both the first and second classification processes, dry centrifugal (semi-free vortex) classification was performed using an Aerofine Classifier manufactured by Nissin Engineering. First, the recovered particles were classified by adjusting the angle of the blade so that the fine particles contained in them were 10 volume% or less, and then the coarse particles were adjusted and classified so that they were 1 volume% or less. Other than that, it was the same as Example 1.

[Example 5]

In both the first classification process and the second classification process, wet centrifugal classification was performed using an i-classifier manufactured by Satake Kagaku Kikai Kogyo. First, the recovered particles were classified so that the fine particles contained in them were 5% by volume or less, and then they were classified so that the coarse particles were 1% by volume or less. Other than that, it was the same as Example 1.

[Comparative Example 1]

The immersion and stirring time of the alkali removal treatment was changed to 1.5 hours, and the classification process was not provided. Other than that, it was the same as Example 1.

[Comparative Example 2]

In the first process, the inlet temperature of the spray dryer was set to 250°C, the immersion stirring time for the alkali removal treatment was set to 1.5 hours, and no classification process was provided. Other than that, it was the same as Example 1.

[Comparative Example 3]

In the classification process, a cyclone manufactured by the company was used, the flow rate of the powder transport line was set to 5 m/s, and the particles collected in the cyclone were recovered. Other than that, it was the same as Example 1.

As shown in Table 1, the powder according to the examples and the resin molded product mixed with this powder have low dielectric constant and dielectric loss tangent. In addition, the resin composition containing the powder according to the examples is excellent in filterability and injectability.

Claims (7)

It is a powder containing hollow particles with cavities inside a non-porous outer shell,
The average particle diameter (D50) of the powder is 1.0 to 10.0 μm, the content of fine particles with a particle diameter of less than 1.0 μm is 10% by volume or less, and the content of coarse particles with a particle size exceeding 8.0 μm is 20% by volume or less,
A powder characterized in that, when the powder is suspended in water, floating particles are 0.5 to 15.0 mass%, suspended particles are 0 to 4.0 mass%, and settled particles are 81.0 to 99.5 mass%. The powder according to claim 1, wherein the particle size variation coefficient (CV value) is 60% or less. A method for producing a resin composition, comprising mixing the powder according to claim 1 or 2 with a resin material. A first step of preparing particles by spray drying an aqueous silicate alkali solution in a hot air stream;
A second process of removing alkali contained in the particles,
Third process of baking the alkali-removed particles
With
A method for producing powder, characterized in that between the first step and the third step, a classification step is provided to remove fine particles with a particle size of less than 1.0 μm and coarse particles with a particle size of more than 8.0 μm. The powder manufacturing method according to claim 4, wherein in the second step, the amount of alkali contained in the particles is reduced to 300 ppm or less. The method according to claim 4 or 5, wherein before the third step, a drying step for drying the hollow particles is provided,
A method for producing powder, characterized in that the classification process is provided between the drying process and the third process. The method for producing powder according to any one of claims 4 to 6, wherein in the classification step, the fine particles and the coarse particles are removed by a wet classification treatment.