JP2022103683A - Silica-based hollow particle, method for producing the same, and resin composition - Google Patents

Abstract

To provide a silica-based particle capable of reducing the dielectric constant and dielectric loss tangent of an insulating material and not obstructing the filterability and injectability of a liquid for forming an insulating material in a manufacturing process, and a method for manufacturing the same.SOLUTION: Provided are a silica-based hollow particle having a cavity inside a nonporous outer shell and having an average particle diameter (D50) of 0.1 to 10 μm, in which when suspended in water, floating particles a are 0.5 to 7.0 mass%, suspended particles b are 0 to 4.0 mass%, and precipitated particles c are 89.0 to 99.5 mass%; and a method for producing the same.SELECTED DRAWING: None

Description

The present invention relates to silica-based hollow particles useful as a filler for an insulating material of a semiconductor, a method for producing the same, and a resin composition.

In recent years, the capacity of data communication in information communication has been increasing, and high-speed processing of communication equipment is required. Insulating materials for semiconductor printed wiring boards used in such communication equipment are required to have a low dielectric constant (low Dk) and low dielectric loss tangent (low Df) in order to realize high-speed communication. ing. If the dielectric constant of the insulating material is high, it leads to dielectric loss, and if the dielectric loss tangent of the insulating material is high, not only it leads to dielectric loss, but also problems such as an increase in calorific value may occur.

In the insulating material of such a printed wiring board of a semiconductor, a resin material which is a main component of the insulating material is being developed in order to realize a low dielectric constant and a low dielectric loss tangent. As such a resin material, for example, an epoxy resin, a polyphenylene ether resin, a fluororesin and the like have been proposed (see, for example, Patent Documents 1 to 5).

On the other hand, such a resin material contains a filler from the viewpoint of durability (rigidity), heat resistance and the like. As this filler, metal oxides such as silica, boron nitride, talc, kaolin, clay, mica, alumina, zirconia, and titania are used (see, for example, Patent Document 3).

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

Among the fillers contained in the insulating material of the semiconductor, silica is excellent in low dielectric constant and low dielectric loss tangent. However, in today's world where the capacity and high-speed processing of data communication are rapidly increasing, further reduction in dielectric constant and low dielectric loss tangent are required. It is also important that the filler of the insulating material of the semiconductor does not interfere with the filterability and the injectability of the insulating material forming liquid in the manufacturing process of the insulating material.

An object of the present invention is to provide silica-based particles that enable low dielectric constant and low dielectric loss tangent of an insulating material and do not interfere with the filterability and injectability of a liquid for forming an insulating material in a manufacturing process, and a method for manufacturing the same. To do.

As a result of diligent research on silica particles useful as fillers for semiconductor insulating materials while the capacity and high-speed processing of data communication are rapidly increasing, the present inventors have conducted diligent research on silica particles that do not contain coarse particles and satisfy predetermined conditions. We have found that the hollow particles can realize low dielectric constant and low dielectric tangentiality of the insulating material and do not interfere with the filterability and injectability of the insulating material forming liquid in the manufacturing process, and complete the present invention. I arrived.

That is, the present invention is a silica-based hollow particle having a cavity inside a non-porous outer shell and having an average particle diameter (D50) of 0.1 to 10 μm, and is a suspended particle when suspended in water. The silica-based hollow particles are characterized in that a is 0.5 to 7.0% by mass, suspended particles b are 0 to 4.0% by mass, and sedimented particles c are 89.0 to 99.5% by mass. ..

Further, the present invention comprises a hollow particle preparation step of spray-drying an alkaline silicate aqueous solution in a hot air stream to prepare hollow particles, and an alkali removing step of neutralizing and removing the alkali contained in the prepared hollow particles with an acid. A method for producing silica-based hollow particles, which comprises a firing step of calcining hollow particles from which alkali has been removed, in which the hollow particles are classified and coarse particles are removed between the hollow particle preparation step and the firing step. The present invention relates to a method for producing silica-based hollow particles, which comprises a step.

The silica-based hollow particles of the present invention can realize low dielectric constant and low dielectric loss tangent of the insulating material, and can increase the transmission speed of the semiconductor and reduce the transmission loss. Further, the silica-based hollow particles of the present invention do not interfere with the filterability and injectability of the insulating material forming liquid in the manufacturing process, and can stably produce an excellent insulating material.

[Silica-based hollow particles]
The silica-based hollow particles of the present invention have cavities inside a non-porous outer shell and have an average particle diameter of 0.1 to 10 μm. When these silica-based hollow particles are suspended in water, the suspended particles are 0.5 to 7.0% by mass, the suspended particles are 0 to 4.0% by mass, and the sedimented particles are 89.0 to 99.5% by mass. %.

Here, the silica system means that silica is the main component, and 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, further preferably 95% by mass or more, and particularly preferably composed of substantially only silica.

The particles of the present invention are hollow particles having cavities inside a non-porous outer shell, and include suspended particles having a light specific density (particles having a high porosity) that float when suspended in water. There is. Therefore, when blended in a resin composition, low dielectric constant and low dielectric loss tangent are realized. Further, since hollow particles having a high void ratio generally have a large particle diameter, controlling the amount of the suspended particles to 0.5 to 7.0% by mass of the whole particles controls the amount of coarse particles. It will be (reduced). Therefore, the filterability and injectability of the resin composition forming liquid in the manufacturing process of the resin composition such as the insulating material are improved, and the surface smoothness after molding can be improved. At this time, the content of coarse particles having a particle diameter of more than 8.0 μm is preferably 10% by volume or less, more preferably 5% by volume or less, and further preferably 1% by volume or less.

The particles having a light specific gravity floating in water tend to have low particle strength because the ratio of the thickness of the outer shell to the particle diameter is small. Therefore, the particles may crack during the production of a resin composition such as an insulating material. The occurrence of cracks in the particles hinders low dielectric constant and low dielectric loss tangent, deteriorates the fluidity of the resin composition forming liquid, and lowers the uniformity of the resin composition (molded product). Or, it becomes a factor that causes voids inside the resin composition. By controlling the amount of suspended particles, cracking of the particles can be suppressed.

In the present invention, since the amount of suspended particles is particularly controlled, the particles having a high void ratio have the preferable characteristics (particularly low dielectric constant and low dielectric loss tangent) of the particles having a high void ratio. Undesirable properties (particularly the occurrence of cracks) are suppressed to the extent that there is no problem. Further, as the suspended particles, particles having a small diameter exist even if the porosity is high, and such particles are less likely to be cracked than the particles having a large diameter in the manufacturing process, and the particles having a high porosity as a whole. Unfavorable characteristics can be suppressed as much as possible.

The content of the suspended particles is preferably 1.0 to 5.0% by mass, more preferably 1.0% by mass to 4.0% by mass, and even more preferably 2.0 to 4.0% by mass. The content of the precipitated particles is preferably 91.0 to 99.5% by mass, more preferably 92.0 to 99.0% by mass, and even more preferably 95.0 to 98.0% by mass.

The ratio of suspended particles, suspended particles and sedimented particles when suspended in water is calculated by collecting and weighing each particle from the suspension and calculating the ratio. Specifically, it will be described in Examples.

Further, the average particle diameter (D50) of the silica-based hollow particles of the present invention is in the range of 0.1 to 10 μm. Those having an average particle size of less than 0.1 μm are difficult to produce by the spray drying method. Further, silica-based particles having an average particle diameter of more than 10 μm are not suitable for semiconductor applications. Considering that it is used for semiconductors, the average particle size is preferably 0.5 to 10 μm, more preferably 1.0 to 5.0 μm.

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

The average particle size (D50), the maximum particle size (D100), and the content of coarse particles are measured by a laser diffraction / scattering method. Specifically, it will be described in Examples.

The porosity of the silica-based hollow particles of the present invention is preferably 5% by volume or more, more preferably 8% by volume or more, still more preferably 10% by volume or more. On the upper limit side, 50% by volume or less is preferable, 35% by volume or less is more preferable, 25% by volume or less is further preferable, and 20% by volume or less is most preferable. With such a porosity, it is possible to reduce the dielectric constant and the dielectric loss tangent, and it is possible to keep the particle strength at a predetermined level or higher and effectively suppress the cracking of the particles. Here, the porosity is calculated from the particle density. Specifically, it will be described in Examples.

The silica-based hollow particles of the present invention are preferably used as a filler for an insulating material of an electronic material such as a semiconductor. Specifically, it can be blended in a copper-clad laminate, a prepreg, a build-up film, or the like for forming a printed wiring board (including a rigid substrate and a flexible substrate). Further, it can be blended in semiconductor package-related materials such as mold resin, mold underfill, and underfill, and adhesives for flexible substrates.

[Resin composition]
The resin composition of the present invention contains the above-mentioned silica-based hollow particles of the present invention. Such a resin composition can be used for the above-mentioned silica-based hollow particles such as an insulating material for electronic materials such as semiconductors.

As the resin contained in the resin composition (liquid for forming a resin composition) of the present invention, a curable resin generally used for electronic materials such as semiconductors can be used. A photocurable resin may be used, but a thermosetting resin is preferable. As such curable resins, epoxy resins, polyphenylene ether resins, fluororesins, polyimide resins, bismaleimide resins, acrylic resins, methacrylic resins, silicone resins, BT resins, cyanate resins and the like are used. Can be mentioned. As epoxy resins, bisphenol type epoxy resin, novolak type epoxy resin, triphenol alkane type epoxy resin, epoxy resin having biphenyl skeleton, epoxy resin having naphthalene skeleton, dicyclopentadienephenol novolak resin, phenol aralkyl type epoxy resin, glycidyl Specific examples thereof include an ester type epoxy resin, an alicyclic epoxy resin, a heterocyclic epoxy resin, and a halogenated epoxy resin. These resins may be used alone or in combination of two or more.

The content of the silica-based hollow particles in the resin composition (liquid for forming the resin composition) of the present invention is such that the mass ratio (A / B) of the silica-based hollow particles A and the curable resin B is 10/100 or more. 95/100 is preferable, and 30/100 to 80/100 is more preferable. With such a mass ratio, it is possible to fully exhibit the function as a filler while maintaining the characteristics of the resin composition forming liquid such as fluidity.

The resin composition (liquid for forming a resin composition) of the present invention preferably contains a curing agent such as a phenol compound, an amine compound, or an acid anhydride. When an epoxy resin is used as the curable resin, the curing agent includes a bisphenol type resin, a novolak resin, a triphenol alkane type resin, a resol type phenol resin, and a phenol aralkyl resin, which have two or more phenolic hydroxyl groups in one molecule. Examples thereof include phenolic 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 such as colorants, stress relaxation agents, defoaming agents, leveling agents, coupling agents, flame retardants, and curing accelerators are added to the resin composition (resin composition forming liquid) as necessary. can do.

The resin composition of the present invention can be obtained by a conventionally known method. For example, a thermosetting resin, silica-based hollow particles, a curing agent, an additive, etc. are mixed and kneaded with a roll mill or the like to prepare a coating liquid (resin composition forming liquid), and after coating on a substrate, heat and ultraviolet rays are applied. It can be obtained by curing with or the like.

[Manufacturing method of silica-based particles]
The method for producing silica-based hollow particles of the present invention comprises a hollow particle preparation step of spray-drying an aqueous alkali silicate solution in a hot air stream to prepare hollow particles, and neutralizing the alkali contained in the prepared hollow particles with an acid. It has an alkali removing step of removing the alkali and a firing step of firing the hollow particles from which the alkali has been removed, and a classification step of classifying the hollow particles and removing coarse particles is provided between the hollow particle preparation step and the firing step. Has been done. In addition, another step such as a drying step may be provided between each step.

By the production method of the present invention, for example, the silica-based hollow particles of the present invention as described above can be produced. That is, according to the manufacturing method of the present invention, it is possible to reduce the dielectric constant and the dielectric loss tangent of the insulating material, and the silica-based particles do not interfere with the filterability and injectability of the insulating material forming liquid in the manufacturing process. Can be manufactured.

Further, usually, when the classification treatment is performed when producing the calcined particles, it is considered preferable to perform the classification treatment at the final stage after the calcining in order to prepare the final particles, but in the production method of the present invention, it is intentionally performed. Perform before the firing process. If the firing step is performed without the classification treatment, coarse particles having a high porosity that should be originally removed will be present. Since the coarse particles having a high porosity are easily cracked, they may be cracked by the stress of shrinkage due to heating. Since the particle size of the debris generated by this crack is small, it cannot be removed in the subsequent classification step, and since it is a dense silica with no voids, it has a low dielectric constant and a low dielectric loss tangent. It becomes a hindrance. By performing the classification treatment before firing as in the manufacturing method of the present invention, such inconveniences can be avoided, and low dielectric constant and low dielectric loss tangent can be more reliably realized in the manufactured particles. Particles corresponding to high-speed data communication can be obtained.

(Hollow particle preparation process)
In the hollow particle preparation step, the alkaline aqueous solution of silicate is spray-dried in a hot air stream to prepare hollow particles.

As the alkali silicate, sodium silicate and potassium silicate, which are soluble in water, are usually used, but sodium silicate is preferable. The SiO ₂ / M ₂ O molar ratio of alkali silicate (where M indicates an alkali metal) is preferably 1 to 5, and more preferably 2 to 4. When the SiO ₂ / M ₂ O molar ratio of alkali silicate is less than 1, not only is it difficult to perform acid cleaning in the alkali removal step because the amount of alkali is too large, but also the deliquescent property of the spray-dried product becomes remarkable. In some cases, the desired silica-based hollow particles may not be obtained. When the SiO ₂ / M ₂ O molar ratio of alkali silicate exceeds 5, the solubility of alkali silicate decreases and it is difficult to prepare an aqueous solution. Even if an aqueous solution can be prepared, the desired silica-based hollow particles are spray-dried. May not be obtained.

The concentration of the aqueous alkali silicate solution as SiO ₂ is preferably 1 to 30% by mass, preferably 5 to 28% by mass. Although it can be manufactured even if it is less than 1% by mass, the productivity is significantly reduced. If it exceeds 30% by mass, the stability as an aqueous alkali silicate solution may be significantly reduced and the viscosity may become high, making spray drying difficult. Even if spray drying is possible, the particle size distribution and the thickness of the outer shell may be difficult. Etc. may become extremely non-uniform, which may limit the use of the final particles.

As the spray drying method, for example, a conventionally known method such as a rotary disk method, a pressure nozzle method, or a 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, more preferably 350 to 550 ° C. The outlet temperature is preferably 120 to 300 ° C, more preferably 130 to 250 ° C. When the inlet temperature and the outlet temperature are in the above ranges, hollow particles having cavities inside can be stably obtained.

(Alkali removal process)
In the alkali removal step, the alkali contained in the prepared hollow particles is neutralized with an acid and removed.

As the acid, mineral acids such as hydrochloric acid, nitric acid and sulfuric acid, organic acids such as acetic acid, tartaric acid and malic acid can be used. Among these, mineral acids such as hydrochloric acid, nitric acid, and sulfuric acid are preferably used, and sulfuric acid is particularly preferable from the viewpoint of valence.

The treatment in this step is not particularly limited as long as it is a treatment using an acid, and a treatment in which the prepared hollow particles are immersed in an acid solution is preferable.

The molar ratio (Ma) / (Msp) of the number of moles of M ₂ O (Msp) and the number of moles of acid (Ma) in the hollow particles when the hollow particles are immersed in the acid aqueous solution is 0.6 to 4.7. Is preferable, and 1 to 4.5 is preferable. When this molar ratio is less than 0.6, the amount of acid is too small for M ₂ O, and the silica skeletonization of silicic acid, which is thought to occur with the removal of alkali, does not proceed, and the hollow particles are partially formed. In some cases, the dissolved alkali silicate may gel. Even if the molar ratio exceeds 4.7, silica skeletonization does not proceed further, and the acid is excessive, which is not economical.

The concentration of the hollow particles when immersed in the acid aqueous solution is preferably 1 to 30% by mass, preferably 5 to 25% by mass, as SiO ₂ . If it is less than 1% by mass, there is no problem in alkali removal and detergency, but the production efficiency is lowered. If it exceeds 30% by mass, the concentration may be too high and the alkali removal and cleaning efficiency may decrease.

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

The residual amount (mass ratio) of the alkali (M) after the completion of the alkali removing step is preferably 300 ppm or less, more preferably 200 ppm or less, further preferably 100 ppm or less, and particularly preferably 50 ppm or less. By sufficiently removing the alkali in this step, it is possible to prevent the coalescence of particles in the subsequent step and prevent the generation of sintered particles in the firing step. Further, it is known that the residual amount (content) of alkali affects the dielectric property. By sufficiently removing the alkali in this step, silica-based hollow particles that enable low dielectric constant and low dielectric loss tangent can be obtained even when an aqueous solution of alikari silicate is used as a raw material.

The amount of alkali in the final product (silica-based hollow particles) is also preferably in the above range, and the amount of alkali in the final product is usually the same as the amount of alkali after the alkali removal step.

For the residual amount of alkali, Na or K is measured using an atomic absorption spectrophotometer using a sample obtained by dissolving particles with an acid. When sodium silicate is used, Na is measured, and when potassium silicate is used, K is measured. Specifically, it will be described in Examples.

(Baking process)
The firing step is a step of firing the hollow particles from which the alkali has been removed. The firing temperature is preferably 600 to 1200 ° C, preferably 900 to 1100 ° C. When the firing temperature is less than 600 ° C., the residual amount of SiOH groups is large and the dielectric loss tangent of the particles becomes high, and it is difficult to obtain the effect of reducing the dielectric loss tangent even when the particles are blended with the resin. When the firing temperature exceeds 1200 ° C., the hollow particles tend to sinter with each other and become irregularly shaped particles or coarse particles, which causes deterioration of the filterability and injectability of the resin composition forming liquid. ..

(Classification process)
In the classification step, hollow particles are classified to remove coarse particles. This classification step is performed between the hollow particle preparation step and the firing step. When the classification treatment is performed after the hollow particles are prepared, it is necessary to perform the classification treatment immediately after the granulation in order to prevent the hollow particles from absorbing (deliquezing) and aggregating / coalescing. Therefore, in actual production, it is preferable that the classification treatment is performed after the alkali removing step. When the classification treatment is performed after the alkali removal step, the classification treatment may be performed after the alkali removal treatment or after the drying treatment after the alkali removal treatment. In order to further enjoy the effects of the present invention, it is preferable to carry out after the drying treatment.

In the classification step, the amount of coarse particles having a particle diameter of more than 8.0 μm is preferably 10% by volume or less, more preferably 5% by volume or less, and further preferably 1% by volume or less. By this classification step, the ratio of suspended particles of the silica-based hollow particles of the present invention can be controlled within a predetermined range.

The classification in the classification step of the present invention means the particle size classification in which the powder is divided 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 classified into dry classification and wet classification. In the wet classification, it is necessary to perform the classification treatment in a state where the particles are suspended in water, and SiOH groups are generated on the surface of the particles, which may adversely affect the dielectric properties. Therefore, the dry classification is preferable.

The classifiers used for dry classification can be roughly classified into gravity classifiers, inertial classifiers, and centrifugal classifiers, and any classifier can be used as long as the object of the present invention can be achieved. However, from the viewpoint of enabling more precise classification, it is preferable to use an inertial classifier or a centrifugal classifier that classifies by utilizing the inertial force of the particles. In particular, since the hollow particles of the present invention are light and centrifugal force is not easily applied to the particles, a classifier that exhibits the characteristics even with such particles is preferable. Examples of such a classifier include an elbow jet manufactured by Nittetsu Mining Co., Ltd., an SG separator manufactured by Nippon Three M Co., Ltd., an aerofine classifier manufactured by Nittetsu Engineering Co., Ltd., and a microspin manufactured by Nippon Pneumatic Industries Co., Ltd. can. Among these, elbow jets manufactured by Nittetsu Mining Co., Ltd. and aerofine classifiers manufactured by Nittetsu Engineering Co., Ltd. are preferable because they can precisely classify light hollow particles.

(Drying process)
In the production method of the present invention, a drying step can be appropriately provided. The drying step can be provided, for example, between the alkali removing step and the classification step, and between the classification step and the firing step, or both. It may be provided multiple times as needed.

As a drying method, heat drying is preferable. The drying temperature is preferably 50 to 400 ° C, more preferably 50 to 200 ° C. Specific examples include a method of drying at a low temperature of about 50 to 200 ° C. over a long period of time, a method of gradually increasing the temperature to dry, and a method of changing the temperature in several stages to dry. be able to.

(Sieving process)
It is preferable to provide a sieving step for sieving the particle mass after the drying step and / or the firing step. The particle mass means, for example, a foreign substance having a particle size of more than 50 μm, and in this step, a sieve having an opening (number of meshes) capable of removing such a particle mass is appropriately used.

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

[Example 1]
Using 30000 g of a water glass aqueous solution (SiO ₂ / Na ₂ Omolar ratio 3.2, SiO ₂ concentration 24% by mass), a flow rate of 0.62 kg / hr to one of the two fluid nozzles and 31800 L / L of air to the other nozzle. Silica hollow particles were obtained by spraying with hot air having an inlet temperature of 400 ° C. at a flow rate of hr (empty / liquid volume ratio 63600). At this time, the outlet temperature was 150 ° C. (hollow particle preparation step).

Then, 5000 g of the silica hollow particles were immersed in 32000 g of a sulfuric acid aqueous solution having a concentration of 10% by mass and stirred for 15 hours. At this time, the solid content (SiO ₂ ) concentration was 10.2% by mass, the temperature of the dispersion liquid was 35 ° C., and the pH was 3.0. The molar ratio (Ma) / (Msp) with the number of moles (Ma) of the acid was 1.2. After the dipping treatment, it was filtered and washed with pure water (alkali removal step).

Then, it was dried in a dryer at 120 ° C. for 24 hours (drying step). After drying, the particles were crushed and sieved through a sieve having an opening of 75 μm to remove coarse particles.

Then, using an in-house cyclone, a dry centrifugal classification treatment was performed at a flow velocity of 5 m / s on the powder transport line (classification step). Particles that passed without being collected by the cyclone were collected by a bag filter.

Finally, the classified particles were heat-treated at 1000 ° C. for 10 hours to obtain silica-based hollow particles (A1) according to the target embodiment (calcination step). After firing, particle lumps (foreign matter) were removed with a sieve having an opening of 150 μm.

In addition, the manufactured silica-based hollow particles (A1) are mixed with the liquid acid anhydride "Ricacid MH700" manufactured by Shin Nihon Rika Co., Ltd. and the imidazole-based epoxy resin curing agent "2PHZ-PW" manufactured by Shikoku Kasei Co., Ltd. It was blended with a liquid epoxy resin "ZX-1059" manufactured by Material Co., Ltd., pre-kneaded with a planetary mill, and then kneaded with three rolls to prepare a liquid for forming a resin composition. In addition, "ZX-1059" was blended in a proportion of 100 parts by mass, "Ricacid MH700" in a proportion of 86 parts by mass, and "2PHZ-PW in a proportion of 1 part by mass. The silica-based hollow particles (A1) were contained in the resin composition. The prepared resin composition-forming liquid was heated at 170 ° C. for 2 hours to cure, and the plate-shaped resin composition according to the example of 50 mm × 50 mm × 1 mm ( A1R) was obtained.

[Example 2]
Except for the classification step, the same procedure as in Example 1 was carried out to produce the silica-based hollow particles (A2) and the plate-shaped resin composition (A2R) according to the examples. In the classification step, a dry inertial classification process was performed using an elbow jet (EJ-15) manufactured by Nittetsu Mining Co., Ltd. In this device, the powder can be divided into three types, F powder (fine powder), M powder (fine powder), and G powder (coarse powder), depending on the classification, and among these, F powder (fine powder) is included. The F-edge distance was adjusted so that the coarse particles exceeding 8.0 μm were 5% by volume or less, and the particles were collected by a bag filter and used in the subsequent steps.

[Example 3]
In the second embodiment, the same applies to the embodiment except that the F edge distance is adjusted to be 1% by volume or less of the coarse particles exceeding 8.0 μm contained in the F powder (fine powder) in the classification step. Silica-based hollow particles (A3) and a plate-shaped resin composition (A3R) were produced.

[Example 4]
In the first embodiment, the silica-based hollow particles (A4) according to the embodiment were similarly classified except that the dry centrifugal (semi-free vortex) classification treatment was performed using an aerofine classifier manufactured by Nisshin Engineering Co., Ltd. in the classification step. ) And the plate-shaped resin composition (A4R) were produced. The classification was performed by adjusting the angle of the blades and the like so that the coarse particles exceeding 8.0 μm contained in the recovered powder were 1% by volume or less.

[Comparative Example 1]
In Example 1, the silica-based hollow particles according to the comparative example were prepared in the same manner except that the immersion stirring time was changed from 15 hours to 1.5 hours in the alkali removing step and the classification treatment (classification step) was not performed. B1) and a plate-shaped resin composition (B1R) were produced.

[Comparative Example 2]
In Example 1, the silica-based hollow particles (B2) and the plate-like resin according to the comparative example were obtained in the same manner except that the inlet temperature of the spray dryer was set to 250 ° C. and the classification step was not performed in the hollow particle preparation step. The composition (B2R) was produced.

[Comparative Example 3]
In Example 1, the silica-based hollow particles (B3) and the plate-shaped resin composition (B3R) according to the comparative example were produced in the same manner except that the classification step was performed after the firing step (with the same classification conditions). ..

The characteristics of the silica-based hollow particles and the resin composition according to the manufactured Examples and Comparative Examples were evaluated. Each evaluation was performed as follows.

(1) Average particle diameter (D50), maximum particle diameter (D100), and coarse particle amount of silica-based hollow particles The particles were measured by a laser diffraction / scattering method.
Specifically, the apparatus was measured by a dry method using a laser micron sizer (LMS-3000) manufactured by Seishin Corporation.
The amount of coarse particles was calculated as a volume ratio of particles exceeding 8.0 μm.

(2) Residual amount of Na in silica-based hollow particles The amount was measured by atomic absorption spectroscopy.
Specifically, the residual amount of Na was measured by pretreating silica-based hollow particles with sulfuric acid and hydrofluoric acid, dissolving them in hydrochloric acid, and using an atomic absorption spectrophotometer (Z-2310 manufactured by Hitachi). ..

(3) Particle density of silica-based hollow particles The particle density was measured by the gas pycnometer method.
Specifically, the particle density was measured using Ultrapyc1200e manufactured by Quantachrome Instruments. Nitrogen gas was used as the gas.

(4) Porosity of silica-based hollow particles Calculated from the above particle density.
Specifically, the porosity was calculated using the following formula (1) using silica density = 2.2 g / cm ³ .
Porosity (%) = [2.22- (particle density of silica-based hollow particles)] /2.2 × 100 ... Equation (1)

(5) Dielectric constant (Dk) and dielectric loss tangent (Df) of silica-based hollow particles
It was measured by the cavity resonator perturbation method.
Specifically, the permittivity (Dk) and the dielectric loss tangent (Df) of the silica-based particles were measured using a network analyzer (MS46122B, manufactured by Anritsu) and a cavity resonator (1 GHz). This measurement was performed according to ASTMD2520 (JIS C2565).

(6) Ratio of Suspended Particles a, Suspended Particles b and Precipitated Particles When Suspended in Water Each particle was recovered from the suspension and weighed, and the ratio was calculated.
Specifically, first, a dispersion liquid was prepared by mixing silica-based hollow particles and water so as to be 0.5% by mass and performing ultrasonic treatment for 10 minutes. After allowing this dispersion to stand at 25 ° C. for 24 hours, the suspended particles a, the suspended particles b and the settled particles c were recovered. Subsequently, each particle was dried at 105 ° C. for 24 hours and then weighed, and the ratio was calculated.

(7) Filtration of Liquid for Forming Resin Composition Using a filter manufactured by Loki Techno Co., Ltd. (SHP type: 30 μm), the amount of liquid flowing per unit area until the filter was clogged was evaluated.

The evaluation criteria are as follows.
⊚: ≧ 1 g / cm ²
〇: 0.5 g / cm ² or more and less than 1.0 g / cm ² Δ: 0.3 g / cm ² or more and less than 0.5 g / cm ² ×: <0.3 g / cm ²

(8) Injection property of resin composition forming liquid Injection was performed 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: Over 200 seconds and within 400 seconds △: Over 400 seconds and within 600 seconds ×: Over 600 seconds

(9) Dielectric constant (Dk) and dielectric loss tangent (Df) of the resin composition
The permittivity (Dk) and dielectric loss tangent (Df) of a plate-shaped molded body (resin composition) of 50 mm × 50 mm × 1 mm are 9.4 GHz using a network analyzer (MS46122B manufactured by Anritsu) and a coaxial resonator. It was measured.

The evaluation was performed by comparison with a resin composition containing no silica-based hollow particles (filler). The evaluation criteria are as follows.

Reduction rate of dielectric constant (Dk) (%) = (dielectric constant without filler addition-dielectric constant with filler addition) / dielectric constant without filler addition x 100

〇: Reduction rate> 0
Δ: Reduction rate = 0
×: Reduction rate <0

Reduction rate of dielectric loss tangent (Df) (%) = (dielectric loss tangent without filler addition-dielectric loss tangent with filler addition) / dielectric loss tangent without filler addition x 100

⊚: Reduction rate 50% or more 〇: Reduction rate 30% or more and less than 50% Δ: Reduction rate 20% or more and less than 30% ×: Reduction rate less than 20%

The above results are shown in Table 1.

As shown in Table 1, the silica-based hollow particles and the resin composition containing the silica-based hollow particles according to the examples have a low dielectric constant and a low dielectric loss tangent. Further, the resin composition forming liquid containing the silica-based hollow particles according to the examples is also excellent in filterability and injectability.

Since the silica-based hollow particles of the present invention can be used as a filler for an insulating material of a semiconductor, they are industrially useful.

Claims (7)

Silica-based hollow particles having cavities inside a non-porous outer shell and having an average particle diameter (D50) of 0.1 to 10 μm.
When suspended in water, the suspended particles are 0.5 to 7.0% by mass, the suspended particles are 0 to 4.0% by mass, and the sedimented particles are 89.0 to 99.5% by mass. Silica-based hollow particles. The silica-based hollow particles according to claim 1, wherein the content of coarse particles having a particle diameter of more than 8.0 μm is 10% by volume or less. A resin composition comprising the silica-based hollow particles according to claim 1 or 2. A hollow particle preparation process for preparing hollow particles by spray-drying an alkaline silicate aqueous solution in a hot air stream, and
An alkali removing step of neutralizing and removing the alkali contained in the prepared hollow particles with an acid, and
The firing step of firing the hollow particles from which the alkali has been removed, and
It is a method for producing silica-based hollow particles having
A method for producing silica-based hollow particles, which comprises a classification step of classifying hollow particles and removing coarse particles between the hollow particle preparation step and the firing step. The method for producing silica-based hollow particles according to claim 4, wherein in the alkali removing step, the amount of alkali contained in the hollow particles is reduced to 200 ppm or less. The method for producing silica-based hollow particles according to claim 4 or 5, wherein the classification step is performed after the alkali-removed hollow particles are dried. The method for producing silica-based hollow particles according to any one of claims 4 to 6, wherein the classification treatment in the classification step is a dry classification treatment.