Hollow particles, method for producing the hollow particles, resin composition, and resin molded article and laminate using the resin composition

Abstract

To provide a hollow particle for improving dielectric properties.SOLUTION: A hollow particle of the present invention contains silica. DSL of the primary particle satisfies the following formula (1), and DST of the primary particle satisfies the following formula (2): 1≤DSL≤1.5...(1), 1≤DST≤1.5...(2), where DSL=D75L / D25L, and D25L and D75L indicate the 25th and 75th values of 100 randomly selected primary particles, respectively when their long diameters are measured and their sizes are arranged in order from smallest to largest by observation with a scanning electron microscopy, and DST=D75T / D25T, and D25T and D75T indicate the 25th and 75th values, respectively, when the short diameters of 100 randomly selected primary particles are measured and the sizes are ordered from smallest to largest by observation with the scanning electron microscopy.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] The present invention relates to hollow particles, a method for producing the hollow particles, a resin composition, and a resin molded article and a laminate using the resin composition. [Background technology]

[0002] For example, in the field of information and communication devices, there is a demand for lower dielectric constants and lower dielectric loss tangents for electronic components (typically resin components) to accommodate communications in high frequency bands. To achieve this, it has been proposed to incorporate air, which has a low relative dielectric constant, into components. Specifically, it has been proposed to introduce air using hollow particles (see, for example, Patent Document 1).

[0003] The recent trend toward higher speeds and larger capacities in information and communication devices has led to demands for further improvements in dielectric properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-56158 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the above problems, and one of its objects is to improve dielectric properties. [Means for solving the problem]

[0006] According to one aspect of the present invention, hollow particles are provided. The hollow particles include silica, and the D of the primary particles SL satisfies the following formula (1), and the D of the primary particles ST satisfies the following formula (2). 1≦D SL ≦1.5 (1) 1≦D ST ≦1.5 (2) where D SL =D 75L / D 25L and D 25L and D 75L The values ​​of the 25th and 75th largest diameters are measured by scanning electron microscope observation of 100 randomly selected primary particles and arranged in order of size from smallest to largest. ST =D 75T / D 25T and D 25T and D 75T The values ​​respectively represent the 25th and 75th minor axis values ​​when 100 randomly selected primary particles are measured and arranged in order of size from smallest to largest in observations using a scanning electron microscope. In one embodiment, the hollow particles have an aspect ratio of less than 2. In one embodiment, the major axis of the hollow particles is 0.1 μm or more and 10 μm or less. In one embodiment, the minor axis of the hollow particles is 0.05 μm or more and 10 μm or less. In one embodiment, the shell of the hollow particle has a thickness of 10 nm or more and 100 nm or less. In one embodiment, the hollow particles have a void ratio of 20% or more and 95% or less. In one embodiment, the hollow particles contain Al, and the molar ratio of Al / Si is 0.0001 or more and 0.1 or less.

[0007] According to another aspect of the present invention, there is provided a resin composition comprising a resin and the hollow particles.

[0008] According to yet another aspect of the present invention, there is provided a resin molded article formed from the resin composition described above.

[0009] According to yet another aspect of the present invention, there is provided a laminate, which has a resin layer formed from the resin composition. In one embodiment, the resin layer has a thickness of 25 μm or less.

[0010] According to yet another aspect of the present invention, there is provided a method for producing the hollow particles, which includes coating a core particle with a shell-forming material to obtain a core-shell particle, and removing the core particle from the core-shell particle. In one embodiment, the core particle contains an alunite-type compound represented by the following general formula (I): M a [Al 1-x M' x ]3(SO4 2- ) y (OH) z mH2O (I) (In formula (I), M is Na + , K. + , NH4 + and H3O + and M' is at least one cation selected from the group consisting of Cu 2+ , Zn 2+ , Ni 2+ , Sn 4+ , Zr 4+ and Ti 4+ and at least one cation selected from the group consisting of: a, m, x, y, and z satisfy the following conditions: 0.8≦a≦1.35, 0≦m≦5, 0≦x≦0.4, 1.7≦y≦2.5, and 4≦z≦7, respectively. In one embodiment, the core-shell particles are calcined before the core particles are removed. [Effects of the Invention]

[0011] According to the present invention, the dielectric properties can be improved by using hollow particles in which the particle size of the primary particles satisfies a predetermined uniformity. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a schematic diagram illustrating a major axis and a minor axis. [Figure 2] 1 is a schematic cross-sectional view of a laminate according to one embodiment of the present invention. [Figure 3A]1 is a TEM photograph (10,000x magnification) of hollow particles in Example 1. [Figure 3B] 1 is a TEM photograph (100,000x magnification) of hollow particles in Example 1. [Figure 3C] 1 is an SEM photograph (10,000x magnification) of hollow particles in Example 1. [Figure 4] 1 is a SEM photograph (6000x magnification) of a cross section of a resin molded body 2 of an example. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0014] (Definition of terms) The definitions of terms used in this specification are as follows. 1. Major axis of particle This is a value measured using a scanning electron microscope (SEM) and is the average value of the long diameter (e.g., L in Figure 1) of randomly selected primary particles. Note that primary particles are the smallest particles observed using SEM and are distinguished from agglomerated particles (secondary particles). 2. Minor diameter of particle This value is measured by SEM observation and is the average value of the minor diameter (for example, T in Figure 1) of randomly selected primary particles. 3. Aspect ratio (major axis / minor axis) This is a value calculated by dividing the minor axis of the particle by the major axis of the particle.

[0015] A. Hollow particles The hollow particles in one embodiment of the present invention are typically made of silica, and the silica content of the hollow particles is, for example, 95% by weight or more, preferably 97% by weight or more, and more preferably 98% by weight or more.

[0016] The hollow particles may contain Al. The Al content is, for example, an Al / Si molar ratio of 0.1 or less, preferably 0.08 or less, and more preferably 0.04 or less. On the other hand, the Al content is, for example, an Al / Si molar ratio of 0.0001 or more. The Al content may be, for example, an Al / Si molar ratio of 0.001 or more.

[0017] The primary particles of the hollow particles are 1≦D SL ≦1.5, preferably 1≦D SL ≦1.4, more preferably 1≦D SL ≦1.3, where D SL is D 75L / D 25L and D 25L and D 75L The values ​​respectively represent the 25th and 75th largest values ​​when the major axis of 100 randomly selected primary particles is measured and arranged in order of size from smallest to largest in observations using a scanning electron microscope.

[0018] The primary particles of the hollow particles are 1≦D ST ≦1.5, preferably 1≦D ST ≦1.4, more preferably 1≦D ST ≦1.3, where D ST is D 75T / D 25T and D 25T and D 75T The values ​​respectively represent the 25th and 75th minor axis values ​​when 100 randomly selected primary particles are measured and arranged in order of size from smallest to largest in observations using a scanning electron microscope.

[0019] The aspect ratio of the hollow particles is preferably less than 2, more preferably 1.9 or less, while the aspect ratio of the hollow particles is 1 or more, preferably greater than 1, more preferably 1.1 or more.

[0020] The shape of the hollow particles can be any appropriate shape. Examples of the shape of the hollow particles include ellipsoid, sphere, aggregate, scale, plate, film, cylinder, prism, flat, go stone, and rice grain. Preferably, the ellipsoid and go stone shapes are used. By using such shapes, for example, the above-mentioned D SL and D ST can be satisfactorily satisfied.

[0021] The major axis of the hollow particles is preferably 0.1 μm or more, and more preferably 0.5 μm or more. This is because, for example, the hollow ratio described below can be fully satisfied. On the other hand, the major axis of the hollow particles is preferably 10 μm or less, and more preferably 5 μm or less. This is because, for example, this can greatly contribute to the miniaturization (thinning) of the members in which they are used.

[0022] The minor axis of the hollow particles is preferably 0.05 μm or more, and more preferably 0.25 μm or more. This is because, for example, the hollow ratio described below can be fully satisfied. On the other hand, the minor axis of the hollow particles is preferably 10 μm or less, and more preferably 5 μm or less. This is because, for example, this can greatly contribute to the miniaturization (thinning) of the members in which they are used.

[0023] The shell thickness of the hollow particles is preferably 10 nm or more, more preferably 15 nm or more. Such a thickness can effectively prevent the hollow particles from breaking, for example, when preparing the resin composition described below. On the other hand, the shell thickness of the hollow particles is preferably 100 nm or less, more preferably 60 nm or less. Such a thickness can fully satisfy the hollow ratio described below, significantly contributing to improved dielectric properties and weight reduction. The shell thickness can be measured by TEM observation. For example, it can be determined by measuring the shell thickness of randomly selected hollow particles and calculating the average value.

[0024] The hollow particle preferably has a void ratio of 20% or more, more preferably 30% or more, even more preferably 40% or more, and particularly preferably 50% or more. Such a void ratio can significantly contribute to, for example, improved dielectric properties and weight reduction. On the other hand, the hollow particle preferably has a void ratio of 95% or less, even more preferably 90% or less. Such a void ratio can effectively prevent breakage of the hollow particle, for example, when preparing the resin composition described below. The void ratio can be calculated from the volume of the core particle and the volume of the hollow particle, described below.

[0025] The pore volume of the hollow particles is preferably 1.5 cm 3 / g or less, more preferably 1.0 cm 3 / g or less.

[0026] The BET specific surface area of ​​hollow particles is, for example, 10 m 2 / g or more, and 2 On the other hand, the BET specific surface area of ​​the hollow particles is preferably 250 m 2 / g or less, more preferably 200m 2 / g or less.

[0027] In one embodiment, the hollow particles are surface-treated with any suitable surface treatment agent, such as at least one selected from the group consisting of higher fatty acids, anionic surfactants, cationic surfactants, phosphate esters, coupling agents, esters of polyhydric alcohols and fatty acids, acrylic polymers, and silicone treatment agents.

[0028] Any suitable method can be adopted as the method for producing the hollow particles, and typically includes coating a core particle with a shell-forming material to obtain a core-shell particle, and removing the core particle from the core-shell particle.

[0029] The core particles have a primary particle size of 1≦D SL It is preferable that the relationship 1≦D≦1.5 is satisfied, and more preferably 1≦DSL ≦1.4, particularly preferably 1≦D SL ≦1.3. The primary particle diameter of the core particle is 1≦D ST It is preferable that the relationship 1≦D≦1.5 is satisfied, and more preferably 1≦D ST ≦1.4, particularly preferably 1≦D ST ≦1.3. SL and D ST As mentioned above,

[0030] The aspect ratio of the core particle is preferably less than 2, and more preferably 1.9 or less. On the other hand, the aspect ratio of the core particle is 1 or more, preferably more than 1, and more preferably 1.1 or more. Examples of the shape of the core particle include ellipsoid, sphere, agglomerate, scale, plate, film, cylinder, prism, flat, go stone, and rice grain. Preferably, the ellipsoid and go stone shapes are used.

[0031] The major axis of the core particle is preferably 0.1 μm or more, more preferably 0.2 μm or more. On the other hand, the major axis of the core particle is preferably 10 μm or less, more preferably 5 μm or less. On the other hand, the minor axis of the core particle is preferably 0.05 μm or more, more preferably 0.1 μm or more. On the other hand, the minor axis of the core particle is preferably 10 μm or less, more preferably 5 μm or less.

[0032] The core particle forming material is the above-mentioned D SL and D ST In one embodiment, the core particle is formed of an alunite-type compound represented by the following general formula (I). M a [Al 1-x M' x ]3(SO4 2- ) y (OH) z mH2O (I) (In formula (I), M is Na + , K. + , NH4 + and H3O +and M' is at least one cation selected from the group consisting of Cu 2+ , Zn 2+ , Ni 2+ , Sn 4+ , Zr 4+ and Ti 4+ and a, m, x, y, and z satisfy 0.8≦a≦1.35, 0≦m≦5, 0≦x≦0.4, 1.7≦y≦2.5, and 4≦z≦7, respectively.

[0033] As the shell forming material, for example, water glass (Na2O·nSiO2) or alkoxysilane such as tetraethoxysilane (Si(OCH2CH3)4) is used.

[0034] The amount of shell-forming material coated can be adjusted by any appropriate method. For example, the amount of coating can be adjusted by controlling the pH value when coating the core particles with a shell-forming material containing water glass. Specifically, since the water glass can be stable in a high pH range (e.g., pH 11 or higher), lowering the pH value causes the water glass molecules to condense, resulting in efficient precipitation of silica on the core particles. Here, when the core particles contain the alunite-type compound, the aqueous slurry of the alunite-type compound itself can exhibit acidic properties (e.g., pH 3 to 5). Therefore, for example, silica can be efficiently precipitated on the core particles without using a pH adjuster (e.g., an acidic solution such as hydrochloric acid) to lower the pH. Furthermore, heating the core particles (e.g., to 80°C to 90°C) when coating them with the shell-forming material can also promote shell formation (specifically, shell precipitation and formation rate).

[0035] The removal of the core particles is typically carried out by dissolving the core particles in an acidic solution. Examples of the acidic solution that can be used include hydrochloric acid, sulfuric acid, and nitric acid. The dissolution temperature is, for example, 30°C to 90°C, and preferably 50°C to 70°C. At such a temperature, the core particles can be efficiently dissolved while preventing problems such as the shell becoming easily broken. In one embodiment, sulfuric acid is used as the acidic solution, for example, from the viewpoint of reusing substances (e.g., salts) obtained by reaction with the core particles.

[0036] In one embodiment, a method for producing hollow particles includes, in this order, coating core particles with a shell-forming material to obtain core-shell particles, calcining the core-shell particles, and removing the core particles from the core-shell particles. When the core particles contain the alunite-type compound, calcination (e.g., in an air atmosphere) is preferably performed before removing the core particles. This is because the alunite-type compound can be acid-resistant, and calcination changes the alunite-type compound, making the calcined core particles more soluble in acidic solutions. Specifically, for core particles containing an alunite-type compound, portions with low agglomeration density are more soluble in acidic solutions, while portions with high agglomeration density are less soluble in acidic solutions, resulting in a dissolution amount in acidic solutions of, for example, approximately 30% by weight. Calcination produces aluminum oxide (Al2O3), which is more soluble in acidic solutions, from the alunite-type compound, thereby improving the solubility of the core particles in acidic solutions.

[0037] The firing temperature is, for example, 300° C. to 1300° C. The firing time is, for example, 1 hour to 20 hours.

[0038] Regardless of the timing of the calcination, the calcination can improve the hydrophobicity of the shell (specifically, convert the silanol groups of the shell to siloxane), thereby improving the dielectric properties of the resulting hollow particles. For example, a method for producing hollow particles includes, in this order, coating core particles with a shell-forming material to obtain core-shell particles, calcining the core-shell particles, removing the core particles from the core-shell particles, and calcining the shell. The conditions for the calcination performed after removing the core particles from the core-shell particles can be the same as those described above.

[0039] In one embodiment of the present invention, the hollow particles are used as a function-imparting agent for a resin material. A resin composition containing the hollow particles will be described below.

[0040] B. Resin composition A resin composition in one embodiment of the present invention contains a resin and the hollow particles.

[0041] Any appropriate resin can be selected as the resin, depending on, for example, the intended use of the resulting resin composition. For example, the resin may be a thermoplastic resin or a thermosetting resin. Specific examples of the resin include epoxy resins, polyimide resins, polyamide resins, polyamideimide resins, polyether ether ketone resins, polyester resins, polyhydroxy polyether resins, polyolefin resins, fluororesins, liquid crystal polymers, and modified polyimides. These may be used alone or in combination of two or more.

[0042] The content of the hollow particles in the resin composition is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and is preferably 90% by weight or less, more preferably 85% by weight or less.

[0043] The resin composition preferably contains 0.5 parts by weight or more, more preferably 1 part by weight or more, of hollow particles per 100 parts by weight of resin, while the resin composition preferably contains 300 parts by weight or less, more preferably 200 parts by weight or less, of hollow particles per 100 parts by weight of resin.

[0044] The volume ratio of hollow particles in the resin composition is preferably 0.1% or more, more preferably 0.5% or more. On the other hand, the volume ratio of hollow particles in the resin composition is preferably 70% or less, more preferably 60% or less. This is because, for example, the processability when producing the resin composition can be excellent.

[0045] The resin composition may contain optional components. Examples of optional components include a curing agent (specifically, a curing agent for the resin), a stress reducing agent, a colorant, an adhesion improver, a release agent, a flow control agent, a defoaming agent, a solvent, and a filler. These may be used alone or in combination of two or more. In one embodiment, the resin composition contains a curing agent. The content of the curing agent is, for example, 1 part by weight to 150 parts by weight per 100 parts by weight of the resin.

[0046] Any suitable method can be used to prepare the resin composition. Specifically, the hollow particles are dispersed in the resin by any suitable dispersion method to obtain the resin composition. Examples of dispersion methods include dispersion using various agitators such as a homomixer, a disperser, or a ball mill, dispersion using a planetary mixer, dispersion using shear force using a three-roll mill, and dispersion using ultrasonic treatment.

[0047] The resin composition is typically formed into a resin molded article having a desired shape. For example, the resin composition is formed into a resin molded article having a desired shape using a mold. When forming the resin molded article, the resin composition may be subjected to any appropriate treatment (for example, a curing treatment).

[0048] In one embodiment of the present invention, the resin composition is used as a resin layer included in a laminate. A laminate having a resin layer formed from the resin composition will be described below.

[0049] C. Laminate FIG. 2 is a schematic cross-sectional view of a laminate according to one embodiment of the present invention. The laminate 10 includes a resin layer 11 and a metal foil 12. The resin layer 11 is formed from the resin composition. Specifically, the resin layer 11 includes the resin and the hollow particles. Although not shown, the laminate 10 may include other layers. For example, a substrate (typically, a resin film) may be laminated on one side of the resin layer 11 (the side on which the metal foil 12 is not disposed). The laminate 10 is typically used as a printed circuit board.

[0050] The thickness of the resin layer is, for example, 5 μm or more, preferably 10 μm or more. On the other hand, the thickness of the resin layer is, for example, 100 μm or less, preferably 50 μm or less, and more preferably 25 μm or less. Such a thickness can, for example, fully accommodate the recent trend toward miniaturization of electronic components.

[0051] Any appropriate metal can be used as the metal for forming the metal foil. Examples include copper, aluminum, nickel, chromium, and gold. These can be used alone or in combination of two or more. The thickness of the metal foil is, for example, 2 μm to 35 μm.

[0052] Any appropriate method can be adopted as a method for producing the laminate. For example, the resin composition is applied to the substrate to form a coating layer, and the metal foil is laminated on this coating layer to obtain a laminate. In another specific example, the resin composition is applied to the metal foil to form a coating layer to obtain a laminate. Typically, the coating layer is cured by subjecting the coating layer to a treatment such as heating or light irradiation at any appropriate timing. When coating, the resin composition may be dissolved in any appropriate solvent and used. [Example]

[0053] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The methods for measuring each property are as follows, unless otherwise specified. 1. Major axis of particle The long diameter of the particles was calculated by SEM observation. Specifically, the long diameter of 100 primary particles randomly selected from the SEM photograph of the particles was measured, and the arithmetic mean (average long diameter) of the obtained measurements was calculated. The magnification of the SEM observation was 10,000 times. 2. Minor diameter of particle The minor diameter of the particles was calculated by SEM observation. Specifically, the minor diameter of 100 primary particles randomly selected from the SEM photograph of the particles was measured, and the arithmetic mean (average minor diameter) of the obtained measurements was calculated. The magnification of the SEM observation was 10,000 times. 3. Aspect Ratio The aspect ratio was calculated by SEM observation, specifically by dividing the average major axis of the particles by the average minor axis of the particles. 4.D SL and D ST It was calculated by SEM observation. Specifically, the major axis of each of 100 primary particles randomly selected from the SEM photograph of the particles was measured, and the 75th value (D 75L ) to the 25th value (D 25L ) and divide by D SL In addition, the minor axis of each of 100 primary particles randomly selected from the SEM photograph of the particles was measured, and the 75th value (D 75T ) to the 25th value (D 25T ) and divide by D ST was calculated. 5. Shell thickness of hollow particles The shell thickness of the particles was calculated by TEM observation. Specifically, the shell thickness of 10 primary particles randomly selected from the TEM photograph of the particles was measured, and the arithmetic mean (average thickness) of the obtained measurements was calculated. The magnifications for TEM observation were 10,000x and 100,000x. 6.Hollow rate The volume was calculated from the volume of the core particle and the volume of the hollow particle. Specifically, it was calculated as (volume per core particle) / (volume per hollow particle) × 100. The volume per core particle and hollow particle was calculated by approximating the actual shape with the volume of a cylinder, with the major axis being the diameter of the circle and the minor axis being the height of the cylinder. 7. Pore volume Measurements were taken using a "BELsorp-max" from Microtrac-Bell Co., Ltd. Specifically, measurements were taken using a constant volume gas adsorption method using nitrogen gas, and the pore volume was determined by analysis using the BJH method. 8.BET specific surface area Measurements were taken using a "BELsorp-mini" from Microtrac BEL Co., Ltd. Specifically, measurements were taken using a constant volume gas adsorption method using nitrogen gas, and the specific surface area was determined by analysis using the BET multipoint method.

[0054] [Example 1] Elliptical alunite particle powder (NaAl3(SO4)2(OH)6, D SL : 1.07, major axis: 1.07 μm, D ST 149 g of the alunite particles (length: 1.11, minor axis: 0.74 μm, aspect ratio: 1.45) was suspended in 1 L of ion-exchanged water to obtain a slurry of alunite particles.

[0055] The resulting alunite particle slurry was then heated to 90°C with stirring, and 142 ml of 0.57 mol / L No. 3 water glass (Na2O 3.14SiO2, Fujifilm Wako Pure Chemical Industries, Ltd.) was added over 4 hours. The resulting slurry was aged for 1 hour, then dehydrated and washed with water to obtain a cake of core-shell particle precursor 1.

[0056] The resulting cake of core-shell particle precursor 1 was then suspended in 1 L of ion-exchanged water and heated to 90°C with stirring, and 142 ml of 0.57 mol / L No. 3 water glass was added to the suspension over a period of 2 hours. The resulting slurry was aged for 1 hour, then dehydrated and washed with water to obtain a cake of core-shell particle precursor 2. The resulting cake of core-shell particle precursor 2 was suspended in 1 L of ion-exchanged water and heated to 90°C with stirring, and 142 ml of 0.57 mol / L No. 3 water glass was added to the suspension over a period of 2 hours. The resulting slurry was aged for 1 hour, then dehydrated and washed with water, and then dried at 100°C for 1 day to obtain a powder of core-shell particles. Here, the obtained core-shell particles were analyzed by EDS measurement using a JEOL Ltd. "JED-2300" to calculate the ratio of Al derived from the core particles to Si derived from the silica shell, and the Al / Si ratio was found to be 3.54.

[0057] The resulting powder of core-shell particles was then fired for 3 hours at 500°C. It is believed that the firing caused the alunite particles to change as follows: NaAl3(SO4)2(OH)6→NaAl(SO4)2+Al2O3+3H2O

[0058] Next, 0.81 L of ion-exchanged water was added to 131 g of the calcined core-shell particles, and the mixture was resuspended under stirring at room temperature. 616 ml of 1.85 mol / L sulfuric acid was then added to the suspension, and the mixture was heated to 60°C and reacted for 3 hours to dissolve the core particles, yielding a hollow silica slurry. The obtained hollow silica slurry was dehydrated and washed with water to form a hollow silica cake, which was then dried at 60°C for 28 hours to obtain hollow silica particles (major axis: 1.16 μm, minor axis: 0.82 μm, aspect ratio: 1.41, D SL :1.03, D ST : 1.04, shell thickness: 33 nm, hollow ratio: 77%, pore volume: 0.22 cm 3 / g, BET specific surface area: 64.4m 2 / g) was obtained.

[0059] Regarding the obtained hollow silica particles, when the ratio of Al derived from the core particles to Si derived from the silica shell was calculated by compositional analysis using EDS measurement with "JED-2300" manufactured by JEOL Ltd., the Al / Si was 0.04. Comparing with the results of the above core-shell particles, it can be said that 99% of Al was dissolved. Also, when the obtained hollow silica particles were analyzed by X-ray diffraction ("EMPYRIAN" manufactured by PANalytical), it was amorphous silica. From the weight of the obtained hollow silica particles, the proportion of silica in the above core-shell particles was 11.4% by weight.

[0060] <TEM Observation> Observation results of the hollow particles of Example 1 by a transmission electron microscope ("JEM-2100PLUS" manufactured by JEOL Ltd.) are shown in FIGS. 3A and 3B. From FIGS. 3A and 3B, it was confirmed that the particles were elliptical hollow particles with a shell (silica layer) thickness of 33 nm. It was confirmed that the hollow particles maintained the elliptical shape of the core particles.

[0061] <SEM Observation> Observation results of the hollow particles of Example 1 by a scanning electron microscope ("JSM-7600F" manufactured by JEOL Ltd.) are shown in FIG. 3C. From FIG. 3C, it was confirmed that the hollow particles had a uniform particle size (D SL : 1.03, D ST : 1.04).

[0062] <Resin Composition> (1) Mixing by ultrasonic treatment 1 g of bisphenol F type epoxy resin ("JER806" manufactured by Mitsubishi Chemical Corporation), 0.38 g of a curing agent ("LV11" manufactured by Mitsubishi Chemical Corporation) and 0.04 g of the hollow silica particles obtained in Example 1 were mixed to obtain Resin Composition 1. The mixing was carried out by subjecting to ultrasonic treatment for 1 minute with "NS-200-60" manufactured by Nippon Seiki Co., Ltd. (2) Mixing by homogenizer 5 g of bisphenol F epoxy resin ("JER806" manufactured by Mitsubishi Chemical Corporation), 1.9 g of curing agent ("LV11" manufactured by Mitsubishi Chemical Corporation), and 0.2 g of the hollow silica particles obtained in Example 1 were mixed to obtain Resin Composition 2. Mixing was carried out using a handheld homogenizer ("T10 Basic" manufactured by IKA Japan Co., Ltd.) at 8000 rpm for 5 minutes. (3) Mixing by a planetary rotation / revolution mixer 5 g of bisphenol F epoxy resin ("JER806" manufactured by Mitsubishi Chemical Corporation), 2.5 g of curing agent ("LV11" manufactured by Mitsubishi Chemical Corporation), and 0.875 g of the hollow silica particles obtained in Example 1 were mixed to obtain Resin Composition 3. Mixing was carried out using a planetary centrifugal mixer ("Kakuhunter SK-300SVII" manufactured by Shashin Kagaku Co., Ltd.) at 1700 rpm for 3 minutes.

[0063] <Resin molded body> The above resin compositions 1-3 were each poured into a 2 mm thick silicone resin mold and cured at 80° C. for 3 hours to obtain resin molded bodies 1-3.

[0064] The obtained molded bodies were cut with a cross-section polisher (JEOL's "IB-09010CP") and the cross sections were observed with an SEM (JEOL's "JSM-7600F", magnification 6000x). As shown in Figure 4, no destruction of the hollow particles was observed in any of the resin molded bodies 1-3. Furthermore, no penetration of the resin into the hollow particles was observed in any of the resin molded bodies 1-3. [Industrial Applicability]

[0065] The hollow particles of the present invention can be suitably used, typically, in electronic materials, but can also be used, for example, in heat insulating materials, sound insulating materials, shock absorbing materials, stress absorbing materials, optical materials, and lightweight materials. [Explanation of symbols]

[0066] L major axis T Short diameter 10 Laminate 11 Resin layer 12 Metal foil

Claims

1. Silica and Al are contained, the silica content is 98% by weight or more, and the Al / Si molar ratio is 0.0001 or more and 0.1 or less, and D of the primary particles ＳＬ satisfies the following formula (1), and the D of the primary particles ＳＴ Hollow particles satisfying the following formula (2), having an aspect ratio of less than 2, a major axis of 0.5 μm or more and 5 μm or less, and a hollow ratio of 50% or more and 90% or less: 1≦D ＳＬ ≦1.5・・・(1) 1≦D ＳＴ ≦1.5・・・(2) Here, D ＳＬ =D ７５Ｌ / D ２５Ｌ and D ２５Ｌ and D ７５Ｌ are the values ​​obtained by measuring the major axis of 100 randomly selected primary particles in observation using a scanning electron microscope, and arranging them in order of size from smallest to largest, and D ＳＴ =D ７５Ｔ / D ２５Ｔ and D ２５Ｔ and D ７５Ｔ The minor axes of 100 randomly selected primary particles were measured by observation with a scanning electron microscope, and the values ​​of the 25th and 75th smallest particles were listed in order of size.

2. 2. The hollow particle according to claim 1, having an aspect ratio of 1.9 or less.

3. Pore ​​volume is 1.5 cm ３ The hollow particles according to claim 1 or claim 2, wherein the molecular weight is 1 / g or less.

4. The hollow particle according to claim 1 , wherein the minor axis is 0.05 μm or more and 10 μm or less.

5. The hollow particle according to any one of claims 1 to 4, wherein the shell has a thickness of 10 nm or more and 100 nm or less.

6. The hollow particle according to any one of claims 1 to 5, which is amorphous.

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