TW202305050A - Powder, production method therefor, and resin composition production method - Google Patents

Abstract

The present invention relates to a powder including hollow particles, each having a cavity inside a non-porous outer shell. The powder has an average particle size (D50) of 1.0-10.0 [mu]m, and contains fine particles of a particle size under 1.0 [mu]m in the amount of 10 vol% or less and coarse particles of a particle size over 8.0 [mu]m in the amount of 20 vol% or less. When the powder is suspended in water, the proportions of floating particles, suspended particles, and settled particles are 0.5-15.0 mass%, 0-4.0 mass%, and 81.0-99.5 mass%, respectively.

Description

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

The present invention relates to powders suitable as fillers for semiconductor insulating materials. In particular, it relates to powders comprising hollow particles with cavities inside a non-porous shell.

In recent years, information communication has developed toward high speed and large capacity. Therefore, materials used in communication equipment require low dielectric constant (low Dk) and low dielectric loss tangent (dielectric positive connection) (low Df). For example, insulating materials having a low dielectric constant and a low dielectric loss tangent are required on printed wiring boards on which semiconductor elements are mounted. If the dielectric constant of the insulating material is high, dielectric loss will occur. In addition, if the dielectric loss tangent of the insulating material is high, not only will it cause dielectric loss, but it may also increase the heat generation.

In order to achieve lower dielectric constant and lower dielectric loss tangent of insulating materials, resin materials are being developed as the main body of insulating materials. As such resin materials, epoxy-based resins, polyphenylene ether-based resins, fluorine-based resins, and the like have been proposed (for example, see Patent Document 1 to Patent Document 5).

Fillers are added to such resin materials from the viewpoint of durability (rigidity) and heat resistance. Metal oxides such as silica, boron nitride, talc, kaolin, clay, mica, alumina, zirconia, and titania are known to be used as fillers (for example, see Patent Document 3).

patent documents Patent Document 1: WO2009/041137 Patent Document 2: Japanese PCT Publication No. 2006-516297 Patent Document 3: Japanese Patent Laid-Open No. 2017-057352 Patent Document 4: Japanese Patent Laid-Open No. 2001-288227 Patent Document 5: Japanese Patent Laid-Open No. 2019-172962

Among materials used as a filler, silicon dioxide is excellent in low dielectric constant and low dielectric loss tangent. However, due to the rapid development of large-capacity and high-speed processing of data communication, low dielectric constant and low dielectric loss tangent are further required. In addition, for the filler, it is also required that the filterability and injectability of the liquid used to form the insulating material are not hindered during the insulating material manufacturing process.

The inventors of the present invention have found that hollow particles that do not contain fine particles and coarse particles and satisfy the specified conditions can achieve low dielectric constant and low dielectric loss tangent of insulating materials, and do not hinder the use in the manufacturing process of insulating materials. Filterability and injectability of liquids forming insulating materials.

That is, the powder according to the present invention includes hollow particles with a cavity inside the non-porous shell, the average particle diameter (D50) is 1.0 μm to 10.0 μm, and the content of fine particles with a particle diameter of less than 1.0 μm is less than 10% by volume , the content of coarse particles with a particle size larger 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% by mass, the suspended particles are 0% to 4.0% by mass, and the settled particles are 81.0% to 99.5% by mass.

In addition, the manufacturing method of the powder according to the present invention has the following steps: the first step of spray-drying the silicic acid alkali aqueous solution in the hot air flow to prepare particles; the second step of removing the alkali contained in the particles; and, In the third step of firing the alkali-removed particles, a classification step is provided between the first step and the third step to remove fine particles with a particle diameter of less than 1.0 μm and coarse particles with a particle diameter of greater than 8.0 μm.

The powder of the present invention can achieve low dielectric constant and low dielectric loss tangent of insulating materials, and further can realize high-speed transmission of semiconductors and reduction of transmission loss. In addition, the filterability and injectability of the liquid used to form the insulating material are not hindered during the semiconductor manufacturing process, and an excellent insulating material can be stably produced.

The powder of the present invention comprises hollow particles with a cavity inside the non-porous shell, and the average particle diameter is 1.0 μm-10.0 μm. Furthermore, the content of particles with a particle diameter of less than 1.0 μm (hereinafter, fine particles) is less than 10 volume %, and the content of particles with a particle diameter of greater than 8.0 μm (hereinafter, coarse particles) is less than 20 volume %. When the powder is suspended in water, the floating particles are 0.5% to 15.0% by mass, the suspended particles are 0% to 4.0% by mass, and the settled particles are 81.0% to 99.5% by mass. In the powder of the present invention, besides the hollow particles, a small amount of solid particles may also be contained. This is because it is possible to accidentally produce solid particles when hollow particles are produced. Since solid particles without cavities have a large specificity, they are basically considered to be latent in sedimentation particles. Preferably, 90% by mass or more of the particles contained in the powder are hollow particles.

Herein, particles dispersed in water when suspended in water are referred to as suspended particles, and particles having a light specific gravity floating in the upper layer (near the water surface) are referred to as floating particles. Such floating particles generally have a high porosity. Therefore, if the number of floating particles added to the resin material increases, the dielectric constant and dielectric loss tangent of the resin product decrease.

Furthermore, by reducing the content of fine particles (less than 10% by volume), the total surface area of all particles becomes smaller. As a result, since the amount of SiOH groups decreases, the dielectric constant can be reduced and the dielectric loss tangent can be reduced. In addition, powders with few fine particles have low adhesiveness and improved fluidity. Therefore, handling and dispersibility are improved. The content of fine particles is preferably 8% by volume or less, more preferably 5% by volume or less, further preferably 3% by volume or less, and most preferably 1% by volume or less.

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

Since the ratio (t/d) of the shell thickness (t) to the particle diameter (d) of the floating particles is small, there is a tendency for particle strength to decrease. Therefore, there is a possibility that the pellets are broken between the process of mixing the resin material and the pellets to molding the resin product (ie, during the manufacturing process). Cracked particles hinder the low dielectric constant and low dielectric loss tangent, and also deteriorate the fluidity of the resin composition, which reduces the uniformity of the resin product (molded product) and creates pores inside the resin product. s reason. However, by controlling the amount of floating particles, the breakage of the particles can be suppressed.

In addition, by controlling the amount of floating particles, it is possible to reduce the non-preferred properties of high-voidity particles while ensuring the preferred properties of high-voidity particles (such as low dielectric constant and low dielectric loss tangent). (such as the generation of cracks) is suppressed to the extent that it is not a problem. Floating particles include particles with a small diameter and high porosity. Compared with large-diameter particles, such particles are less likely to be broken during the manufacturing process, and as a whole, the undesirable characteristics of high-voidity particles can be suppressed as much as possible. The content of the floating particles is preferably 0.5% by mass to 14.0% by mass, more preferably 0.5% by mass to 13.0% by mass, even more preferably 0.5% by mass to 12.0% by mass. In addition, the content of the sedimentation particles is preferably 82.0% by mass to 99.5% by mass, more preferably 83.0% by mass to 99.5% by mass, and even more preferably 84.0% to 99.5% by mass.

In addition, the average particle diameter (D50) of the powder is in the range of 1.0 μm to 10.0 μm. In the case where the average particle diameter is less than 1.0 μm, since fine particles are abundant, the specific surface area becomes high (high SiOH group content), and it is difficult to obtain excellent dielectric characteristics. In addition, powders with an average particle size larger than 10 μm are not suitable for semiconductor applications. In the case of semiconductor applications, the average particle diameter is preferably 1.5 μm to 10.0 μm, more preferably 2.0 μm to 5.0 μm.

In addition, the maximum particle diameter (D100) is preferably 50 μm or less, more preferably 40 μm or less, further preferably 30 μm or less. The maximum particle diameter (D100) is preferably 10 times or less, more preferably 8 times or less, the average particle diameter (D50). Usually more than 2 times, if the requirements of the present invention are met, it can also be more than 5 times.

Further, the particle size variation coefficient (CV value) of the powder is suitably below 60%. Accordingly, when added to a resin material, low dielectric constant and low dielectric loss tangent can be stably realized. In addition, improvement of the surface smoothness of the resin product can be achieved. The particle size coefficient of variation is more preferably 55% or less, more preferably 50% or less.

The porosity of the powder is preferably 10% by volume or more, more preferably 20% by volume or more, and still more preferably 30% by volume or more. In addition, it is preferably 70% by volume or less, more preferably 60% by volume or less, further preferably 50% by volume or less, and most preferably 40% by volume or less. With such a porosity, it is possible to achieve a low dielectric constant and a low dielectric loss tangent, maintain the particle strength at a predetermined level or more, and effectively suppress the cracking of the particles.

Herein, silica-based particles containing silica as a main component are suitable for the particles constituting the powder. Therefore, in addition to silica, the hollow particles (shell) contained in the powder may also contain inorganic oxides such as alumina, zirconia, and titania. The content of silicon dioxide in the particles is preferably at least 70% by mass, more preferably at least 90% by mass, further preferably at least 95% by mass, and particularly preferably composed substantially only of silicon dioxide.

[resin composition]

A resin composition is prepared by adding the above powder and resin material. Such a resin composition is an insulating material for electronic materials such as semiconductors, etc. Specifically, it can be used for copper-clad laminates, prepregs, and build-up films that form printed wiring boards (including rigid substrates and flexible substrates). (Birdapp film) and so on. In addition, it can be used in materials related to semiconductor packaging such as mold resins, mold underfills, underfills, and adhesives for flexible substrates.

As the resin, curable resins generally used in electronic materials such as semiconductors can be used. A photocurable resin may also be used, but a thermally curable resin is preferable. Examples of curable resins include epoxy resins, polyphenylene ether resins, fluororesins, polyimide resins, bismaleimide resins, acrylic resins, and methacrylic resins. , Silicone resin, BT resin, cyanate resin, etc. Furthermore, examples of epoxy resins include bisphenol-type epoxy resins, novolac-type epoxy resins, trisphenol-methane-type epoxy resins, epoxy resins having a biphenyl skeleton, and cyclic epoxy resins having a naphthalene skeleton. Oxygen resin, dicyclopentadiene phenol novolac resin, phenol aralkyl type epoxy resin, glycidyl ester type epoxy resin, alicyclic epoxy resin, heterocyclic type epoxy resin, halogenated epoxy resin, etc. These resins may be used alone or in combination of two or more.

In the resin composition, the powder A and the curable resin B are preferably contained in a mass ratio (A/B) of 10/100 to 95/100. Thereby, the function as a filler can fully be exhibited, maintaining the characteristic of a resin composition, such as fluidity. The mass ratio (A/B) is more preferably 30/100 to 80/100.

Furthermore, the resin composition preferably contains curing agents such as phenolic compounds, amine compounds, and acid anhydrides. In the case of using an epoxy resin as the curable resin, examples of the curing agent include resins having two or more phenolic hydroxyl groups in one molecule (bisphenol-type resins, novolac-type resins, trisphenol-methane-type resins, Resole type phenolic resin, phenol aralkyl resin, biphenyl type phenolic resin, naphthalene type phenolic resin, cyclopentadiene type phenolic resin and other phenolic resins) and methyl hexahydrophthalic acid, methyl tetrahydrophthalic acid Anhydrides such as dicarboxylic acid and methylnadic anhydride. Various additives (colorants, stress relieving agents, defoamers, leveling agents, coupling agents, flame retardants, curing accelerators, etc.) can be added to the resin composition as needed.

As a method for producing the resin composition, conventionally known methods can be applied. For example, curable resin, powder, curing agent, additives, etc. are mixed and kneaded with a roller press or the like. The obtained resin composition is coated on a substrate, and cured by heat, ultraviolet rays, or the like.

[Manufacturing method of powder]

The manufacturing method of the powder of the present invention has the following steps: the first step of spray-drying the silicic acid alkali aqueous solution in the hot air flow to prepare the particles; the second step of removing the alkali contained in the prepared particles; and, In the third step of firing the particles with alkali removed, there is a step of classifying the particles between the first step and the third step 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 ( grading process). Moreover, other processes, such as a drying process, may be provided between each process. Through such steps, the above-mentioned powder can be obtained.

It is generally considered that, in the case of producing pellets by firing, it is preferable to perform a classification treatment after firing in order to adjust the particle size. In this context, however, the classification process is intentionally performed prior to firing. In the case where the firing process is performed without classifying, the firing is carried out in a state where there are fine particles to be removed, and the fine particles are sintered together with other particles. Therefore, the subsequent classification treatment cannot remove fine particles. In addition, there are coarse particles with high void ratio that should be removed. Since the coarse particles with a high porosity are easily broken, they may be broken due to shrinkage stress or the like caused by heating. Fragments generated by cracking are dense silicon dioxide without voids, which prevents low dielectric constant and low dielectric loss tangent. These undesirable conditions can be avoided if grading is done prior to firing. Therefore, the low dielectric constant and low dielectric loss tangent of the particles can be realized more reliably, and the particles corresponding to the high-speed data communication can be obtained. In addition, classification treatment may be performed again after firing. Each step will be described in detail below.

(first process)

In this process, the silicic acid alkali aqueous solution is spray-dried in a hot air flow, and granulated to obtain silica-based particles. In addition, this step is performed to obtain hollow particles, but it is difficult to turn all the particles into hollow particles, so the silica-based particles obtained by granulation may eventually contain solid particles. In this case, solid particles are also included in the powder obtained through the steps described later. However, if the powder has the above characteristics, even if it contains solid particles, the desired effect can be obtained.

The molar ratio (SiO ₂ /M ₂ O) of SiO ₂ and M ₂ O (M is an alkali metal) of the silicic acid base is preferably 1-5, more preferably 2-4. When the molar ratio is less than 1, since the amount of alkali is too large, it is difficult to completely remove it even if acid cleaning is performed in the alkali removal step. Furthermore, since the deliquescent property of the spray-dried product becomes large, it is difficult to obtain the desired hollow particles. When the molar ratio is greater than 5, the solubility of the silicate base 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 as the silicic acid alkali aqueous solution is preferably 1% by mass to 30% by mass, more preferably 5% by mass to 28% by mass. Even if it is less than 1% by mass, it can be produced, but the productivity is remarkably lowered. If it is more than 30% by mass, the stability as a silicic acid alkali aqueous solution will be remarkably reduced, and it will become highly viscous, and spray drying may not be possible. Even if spray drying is possible, there are cases where the particle size distribution, shell thickness, etc. become extremely non-uniform, and the use of the obtained particles is limited. As the silicate base, sodium silicate and potassium silicate which are soluble in water can be used. Sodium silicate is preferred.

As the spray drying method, conventionally known methods such as a rotating disk method, a pressurized nozzle method, and a two-fluid nozzle method can be used, for example. In this context, the two-fluid nozzle method is suitable.

In spray drying, the inlet temperature of the spray dryer is preferably 300°C to 600°C, more preferably 350°C to 550°C. In addition, the outlet temperature is preferably 120°C to 300°C, more preferably 130°C to 250°C. Through such temperature setting, hollow particles can be stably obtained.

(second process)

Next, the alkali contained in the granules obtained by granulating in the first step is removed. A method of neutralization by addition of acid is suitable. The treatment is preferably carried out by immersing the particles in an acid solution. In this case, the molar ratio (Ma/Msp) of the molar number (Ma) of the acid to the molar number (Msp) of M ₂ O in the particles is preferably 0.6 to 4.7, more preferably 1 to 4.5. When the molar ratio is less than 0.6, the amount of acid is too small relative to M ₂ O. Therefore, the silica skeletonization of silicic acid, which is thought to occur simultaneously with the alkali removal, does not proceed, the particles are partially dissolved, and the dissolved silicic acid alkali may be gelled. Even if the molar ratio exceeds 4.7, the skeletonization of silica will not proceed further, and excess acid is not economical.

In addition, it is preferable to immerse the particles in an aqueous acid solution so that the concentration (calculated as SiO ₂ ) of the particles is 1% by mass to 30% by mass. When it is less than 1% by mass, there is no problem in alkali removal and cleaning properties, but production efficiency decreases. If it exceeds 30% by mass, the concentration will be too thick, and the alkali removal and cleaning efficiency will decrease. More preferably, it is 5 mass % - 25 mass %.

The conditions for immersion in the aqueous acid solution are not particularly limited as long as the alkali can be removed to a desired amount, but usually the treatment temperature is 5°C to 100°C, and the treatment time is 0.5 hours to 24 hours. After the immersion treatment, washing is preferably performed by a conventionally known method. For example, filter and wash with pure water. In addition, the above-mentioned acid treatment and cleaning may be repeated as necessary.

The residual amount (mass ratio) of the base (M) after the base is removed is preferably 300 ppm or less, more preferably 200 ppm or less, further preferably 100 ppm or less. By sufficiently removing the alkali in this step, it is possible to prevent particles from sticking in the subsequent step, and to prevent generation of sintered particles in the firing step. In addition, it is known that the residual amount (content) of the base affects the dielectric properties. By sufficiently removing the alkali in this step, particles capable of lowering the dielectric constant and lowering the dielectric loss tangent can be obtained even when an aqueous alkali solution of silicic acid is used as the raw material.

In addition, the alkali amount of the final product (particles constituting the powder) is also preferably within the above-mentioned range, and is usually the same as the alkali amount after the alkali removal step.

The residual amount of alkali can be measured with an atomic absorption spectrophotometer using the powder dissolved by acid as a sample. Measure Na when using sodium silicate and measure K when using potassium silicate. Specifically described in the embodiment.

As the acid used in this step, 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 having a large valency is particularly preferable.

(third process)

Next, the alkali-removing-treated pellets are fired. The firing temperature is preferably 600°C to 1200°C, more preferably 900°C to 1100°C. When the firing temperature is lower than 600° C., the residual amount of SiOH groups is large, and the dielectric loss tangent of the particles becomes high. Therefore, even if it is added to the resin, it is difficult to obtain the effect of reducing the dielectric loss tangent. When the firing temperature is greater than 1200°C, the particles are easily sintered with each other, so irregular-shaped particles and coarse particles are easily produced. This causes the filterability and injectability of a resin composition to fall.

(grading process)

By performing classification treatment between the first step and the third step, fine particles and coarse particles can be removed. When classification treatment is performed before alkali removal, it is necessary to perform classification treatment immediately after granulation in order to prevent hollow particles from agglomerating and sticking due to moisture absorption (deliquescence). In addition, when classification treatment is performed before firing, classification treatment may be continued after the alkali removal treatment.

Through the classification process, the amount of fine particles is reduced to 10% by volume or less. Preferably it is 8 volume % or less, More preferably, it is 5 volume % or less, More preferably, it is 3 volume % or less, Most preferably, it is 1 volume % or less. In addition, 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, further preferably 5 volume % or less, most preferably 1 volume % or less. Through this classification process, the proportion of floating particles present in the powder can be controlled within a predetermined range. In addition, usually the content of fine particles and coarse particles of the final product does not change much compared to the content after the classification process.

The classification treatment in the classification step refers to particle size classification in which the powder is separated according to the particle size for the purpose of making the particle size of the powder uniform. As the operation of this particle size classification, fluid classification can be mentioned, and fluid classification can be divided into dry classification and wet classification.

The classifiers used in dry classification can be roughly divided into gravity classifiers, inertial classifiers, and centrifugal classifiers in principle. More precise classification can be carried out using inertial classifiers and centrifugal classifiers. Examples of classifiers that can precisely classify light particles that are difficult to apply centrifugal force include Elbow-Jet manufactured by Nippon Steel Mining Co., Ltd., SG Separator manufactured by 3M Corporation, and Nissin Engineering Co., Ltd. Aerofine Classifier (エアロファインクラシファイア), manufactured by Japan PNEUMATIC (ニューマチック) Industry Co., Ltd., Microspin. Among these, Elbow-Jet and Aerofine Classifier are preferable.

Classifiers used in wet classification can be roughly divided into gravity classifiers and centrifugal classifiers in principle. By using a centrifugal classifier, more precise classification can be performed. Examples of classifiers that can precisely classify even light particles that are difficult to apply centrifugal force include Hidro Cyclon manufactured by Nippon Chemical Machinery Co., Ltd., Superclon manufactured by Murata Industries, Ltd., and Aikra Sifia manufactured by Satake Chemical Machinery Co., Ltd. Among these, AIKRASIFIA is preferable. According to wet classification, when removing fine particles, coarse particles with small specific gravity can be removed together, and classification efficiency can be improved.

The removal of fine particles and coarse particles can be carried out simultaneously or separately. When each is performed separately, either the removal of fine particles or the removal of coarse particles may be performed first. In addition, each treatment of the removal of fine particles and the removal of coarse particles may be divided into multiple times.

In addition, a drying treatment step may be appropriately provided in the manufacturing process. The drying treatment may be provided between the alkali removal treatment and the classification treatment, between the classification treatment and firing, at both places, or between the alkali removal treatment and firing. Can be set as many times as needed. In addition, drying treatment may be performed before firing, and classification treatment may be performed between drying treatment and firing. In order to better enjoy the effect of the present invention, it is preferable to carry out classification treatment and firing after drying treatment. As the drying treatment, heat drying is suitable. The drying temperature is preferably 50°C to 400°C, more preferably 50°C to 200°C. Specifically, a method of drying at a low temperature of about 50°C to 200°C over a long period of time, a method of gradually increasing the temperature and drying, and a method of drying by changing the temperature in several steps can be exemplified.

Further, it is preferable to provide a sieving treatment for sieving the particle lumps at least one of after drying and after firing. In addition, the particle agglomerate refers to, for example, a particle agglomerate having a particle diameter greater than 50 μm, and a sieve having a pore size (mesh number) capable of removing such a particle agglomerate is suitably used.

Example

Hereinafter, examples of the present invention will be specifically described.

[Example 1]

Hollow particles are obtained by spraying 30,000 g of water glass aqueous solution (SiO ₂ /Na ₂ O molar ratio 3.2, SiO ₂ concentration 24% by mass) in hot air at an inlet temperature of 400°C to obtain hollow particles. Water glass aqueous solution is supplied at a flow rate of 0.62kg/hr, and air is supplied at a flow rate of 31800L/hr (air/liquid volume ratio 63600) from another nozzle. At this time, the outlet temperature was 150° C. (first step). In the first process, there is also the possibility of granulating to obtain a small amount of solid particles, but it is not necessary to remove the solid particles before entering the next process.

Next, 5,000 g of the hollow particles (that is, particles obtained by granulation in the first step) were immersed in 32,000 g of a sulfuric acid aqueous solution having a concentration of 10% by mass, and stirred for 15 hours. The solid content (SiO ₂ ) concentration was 10.2% by mass. In addition, since sulfuric acid is a divalent acid, the ratio (Ma/Msp) of the number of moles of acid (Ma) to the number of moles of base (Na ₂ O) (Msp) is 3.3. The temperature of the dispersion liquid was 35° C., and the pH was 3.0. After this immersion treatment, filter washing is performed with pure water (second step).

Next, drying treatment was performed at 120° C. for 24 hours using a drier. After drying, crush and sieve through a 75 μm sieve to remove particle lumps.

Next, dry-type centrifugal classification treatment was performed using a cyclone manufactured by our company at a flow rate of 5 m/s in the powder conveying line (the first classification step). Particles that pass through without being captured by the cyclone (ie, particles with coarse particles removed) are recovered with a bag filter. Then, dry-type inertial classification treatment (second classification process) was performed using Elbow-Jet (EJ-15) manufactured by Nippon Steel Mining Co., Ltd. If this device is used for grading, it can be divided into three kinds of particles: F powder (fine powder), M powder (fine powder) and G powder (coarse powder). At this time, the F edge distance is adjusted so that the fine particles contained in the F powder (fine powder) are 1% by volume or less. Recover F powder for use in subsequent processes.

By heating the recovered particles at 1000° C. for 10 hours, a powder containing hollow particles was obtained (third step). In addition, after firing, lumps of particles were removed with a sieve having a hole diameter of 150 μm.

Add the obtained powder to the liquid epoxy resin "Nippon Steel Chemical & Material Co., Ltd." In the ZX-1059 manufactured by the company (Nippon Tetsu Chemical & Material Co., Ltd.). Here, 100 parts by mass of "ZX-1059", 86 parts by mass of "Rikasid MH700", and 1 part by mass of "2PHZ-PW" were added so that the proportion of the powder of the additives was 35% by volume. This additive 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) of 50 mm×50 mm×1 mm.

The physical properties of the powders and resin moldings obtained as described above were measured and evaluated. The results are shown in Table 1 together with the preparation conditions. The same was done in other Examples and Comparative Examples.

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

The particle size distribution of the powder was measured dry-type using a particle size analyzer (Laser MicroSizer LMS-3000 manufactured by Seishin Corporation). According to the measurement results, the volume average particle diameter (D43), the average particle diameter (D50), and the maximum particle diameter (D100) are obtained. Further, the particle size distribution is analyzed, and the volume ratios of coarse particles larger than 8.0 μm and fine particles smaller than 1.0 μm are calculated as the amount of coarse particles and the amount of fine particles.

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 size (D43)) × 100 Standard deviation (τ) = (ΣXi(Di-D43)^2/ΣXi)^(1/2)

(2) Residual amount of alkali

After the powder was pretreated with sulfuric acid and hydrofluoric acid, it was 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 the particles contained in the powder was measured by the gas pycnometer method using Ultrapyc 1200e manufactured by Quantachrome Instruments. As the gas, nitrogen gas was used.

From this particle density, the porosity (%) was calculated by the formula "[2.2- (particle density) ]/2.2 × 100". If the powder consists of silica particles, in this formula a silica density of 2.2 g/cm ³ is used.

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

The dielectric constant (Dk) and dielectric loss tangent (Df) were measured by a cavity resonator perturbation method using a network analyzer (manufactured by ANRITSU Corporation, MS46122B) and a cavity resonator (1 GHz). Measured according to ASTM D2520 (JIS C2565).

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

First, the powder and water were mixed so as to be 5% by mass, and ultrasonic treatment was performed for 10 minutes. After the obtained dispersion was left to stand at 25° C. for 24 hours, floating particles, suspended particles and settled particles were recovered respectively. Next, each particle was dried at 105° C. for 24 hours, then measured, and the ratio thereof was calculated.

(6) Filterability of the resin composition

Using a filter (SHP type: 30 μm) manufactured by ROKI TECHNO Corporation (ロキテクノ Corporation), the evaluation was performed in terms of the amount of liquid per unit area until the filter was clogged.

The evaluation criteria are as follows. ◎: ≧1 g/cm ² 〇: 0.5 g/cm ² to less than 1.0 g/cm ² △: 0.3 g/cm ² to less than 0.5 g/cm ² ×: <0.3 g/cm ²

(7) Injectability of resin composition

The resin composition was injected between glass plates having a gap of 20 μm, and the time required for filling 25 mm was evaluated.

The evaluation criteria are as follows. ◎: Within 200 seconds 〇: More than 200 seconds and within 400 seconds △: More than 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). The comparison with the resin molded product without powder (filler) was carried out by the following formula, and the evaluation was performed according to the following criteria.

Decrease rate (%) of dielectric constant (Dk) = (dielectric constant without powder addition - dielectric constant with powder addition) / dielectric constant without powder addition × 100 〇: Reduction rate > 0 △: Reduction rate = 0 ×: reduction rate <0

Reduction rate (%) of dielectric loss tangent (Df) = (dielectric loss tangent without powder addition - dielectric loss tangent with powder addition) / dielectric loss tangent without powder addition × 100 ◎: The reduction rate is more than 50% 〇: Reduction rate of 30% or more and less than 50% △: The reduction rate is more than 20% and less than 30% ×: The reduction rate is less than 20%

[Example 2]

In the second classification step, classification was performed by dry centrifugation (semi-free vortex) using Aerofine Classifier manufactured by Nissin Engineering Co., Ltd. The blade angle and the like are adjusted so that the fine particles contained in the particles recovered by classification are 1% by volume or less. Other than that, it is the same as in Example 1.

[Example 3]

In the second classification step, a wet centrifugal classification treatment was carried out using AIKRA SIFIA manufactured by Satake Chemical Machinery Industry Co., Ltd. The classification is carried out so that the fine particles contained in the recovered particles are 1% by volume or less, and the coarse particles are 1% by volume or less. Other than that, it is the same as in Example 1.

[Example 4]

Both the first classification step and the second classification step were classified by dry centrifugation (semi-free vortex) using Aerofine Classifier manufactured by Nissin Engineering Co., Ltd. First, classification is performed by adjusting blade angles, etc. so that fine particles contained in recovered particles are 10% by volume or less, and then, classification is performed so that coarse particles are 1% by volume or less. Other than that, it is the same as in Example 1.

[Example 5]

Both the first classification step and the second classification step were subjected to wet centrifugal classification treatment using Aircraft made by Satake Chemical Machinery Industry Co., Ltd. First, classification is performed so that fine particles contained in recovered particles are 5% by volume or less, and then, classification is performed so that coarse particles are 1% by volume or less. Except for this, it carried out similarly to Example 1.

[Comparative example 1]

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

[Comparative example 2]

In the first step, the inlet temperature of the spray dryer was set to 250° C., the immersion stirring time of the alkali removal treatment was set to 1.5 hours, and the classification step was not provided. Other than that, it is the same as in Example 1.

[Comparative example 3]

In the classification process, the cyclone manufactured by our company is used, and the flow velocity of the powder conveying line is set to 5m/s, and the particles captured by the cyclone are recovered. Other than that, it is the same as in Example 1.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example 1 Comparative example 2 Comparative example 3 graded graded graded graded graded No rating No rating graded After drying process After drying process After drying process After drying process After drying process - - After drying process first stage Centrifugal fractionation (free vortex) Centrifugal fractionation (free vortex) Centrifugal fractionation (free vortex) Centrifugal fractionation (semi-free vortex) Centrifugal classification (wet) - - inertia classification second stage inertia classification Centrifugal fractionation (semi-free vortex) Centrifugal classification (wet) Centrifugal fractionation (semi-free vortex) Centrifugal classification (wet) - - - Spray granulation process SiO ₂ /Na ₂ O Morby 3.2 ← ← ← ← ← ← ← _SiO2 concentration quality% twenty four ← ← ← ← ← ← ← Inlet temperature ℃ 400 ← ← ← ← ← 250 400 output temperature ℃ 150 ← ← ← ← ← 50 150 Neutralization and cleaning process acid type - sulfuric acid ← ← ← ← ← ← ← Ma/Msp Morby 3.3 ← ← ← ← ← ← ← concentration quality% 10 ← ← ← ← ← ← ← time HR 15 15 15 15 15 1.5 1.5 15 drying process temperature ℃ 120 ← ← ← ← ← ← ← time HR twenty four ← ← ← ← ← ← ← Firing process (sieve) Residual ingredients on the sieve few few few few few many many many Powder Physical Properties Average particle size (D50) μm 5.9 4.2 3.3 2.2 2.5 6.8 6.6 9.7 Maximum particle size (D100) μm 18.6 16.4 11.1 7.5 7.6 58.7 51.7 35.1 CV value % 41 51 44 41 37 99 92 48 Tiny particles (less than 1.0μm) volume% 0.0 0.8 1.0 9.4 3.1 12.2 14.4 0.6 Coarse particles (greater than 8.0μm) volume% 10.5 3.8 0.1 0.0 0.0 34.8 31.6 48.2 Na residue ppm 74 74 74 74 74 371 371 74 particle density g/ ^cm3 1.3 1.5 1.6 1.9 1.8 1.3 2.2 1.1 porosity % 41 32 27 14 18 41 0 50 Dielectric constant (Dk) - 2.2 2.2 2.3 2.5 2.5 2.2 3.5 2.0 Dielectric loss tangent (Df) - 3.0E-04 3.0E-04 4.0E-04 5.0E-04 5.0E-04 1.0E-03 2.0E-03 1.0E-04 Particle ratio floating particles quality% 10.3 8.6 2.7 1.0 2.2 11.6 0.0 22.0 Suspended particles quality% 0.6 1.0 0.9 0.5 0.4 0.2 1.5 0.6 Fallout quality% 89.1 90.4 96.4 98.5 97.4 88.2 98.5 77.4 Physical Properties of Resin Composition Filterability - ○ ○ ○ ◎ ◎ x x x injection - △ △ ○ ◎ ◎ x x x Physical properties of resin moldings Dielectric constant (Dk) - ○ ○ ○ ○ ○ x × (solid) × (broken) Dielectric loss tangent (Df) - ○ ○ ○ ○ ○ x × (solid) × (broken)

As shown in Table 1, the dielectric constant and dielectric loss tangent of the powder described in the examples and the resin molded article added with the powder were low. In addition, the resin composition to which the powder described in the examples was added was excellent in filterability and injectability.

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Claims (7)

A powder, characterized in that the powder contains hollow particles with a cavity inside a non-porous shell, the average particle size (D50) of the powder is 1.0 μm to 10.0 μm, and the particle size is smaller than 1.0 μm. The content of particles is less than 10% by volume, and the content of coarse particles with a particle size greater than 8.0μm is less than 20% by volume. When the powder is suspended in water, the floating particles are 0.5% by mass to 15.0% by mass, and the suspended particles are 0% by mass. ~4.0% by mass, sedimentation particles are 81.0% by mass to 99.5% by mass. The powder as claimed in item 1, the particle size variation coefficient (CV value) of the powder is below 60%. A method for producing a resin composition, characterized in that the powder as claimed in claim 1 or 2 is added to the resin material. A method for producing a powder, characterized in that the production method has the following steps: a first step of spray-drying an aqueous solution of alkali silicic acid in a hot air flow to prepare granules; a second step of removing the alkali contained in the granules The second process; and the third process of firing the particles from which the alkali has been removed, wherein fine particles with a particle diameter of less than 1.0 μm and particles with a particle diameter greater than 8.0 μm are disposed between the first process and the third process. Classification process of coarse particles. The method for producing powder 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 for producing powder according to Claim 4 or 5, wherein, before the third step, a drying step of drying the particles is provided, and between the drying step and the third step In between, the classification process is provided. 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 wet classification treatment.