Hollow particles and methods for manufacturing the same

Abstract

A hollow particle having excellent dielectric properties is provided. The hollow particle according to an embodiment of the present invention has a hollow shell inside. The shell is silica containing aluminum. The amount of aluminum present is greater in the first portion than in the second portion. The first portion is located on the inner side in the thickness direction of the shell. The second portion is located on the outer side in the thickness direction of the shell compared to the first portion.

Description

Technology Field

[0001] The present invention relates to a hollow particle having a hollow shell inside and a method for manufacturing the same. Background Technology

[0002] For example, in the field of information and communication devices, in order to respond to communication in the high-frequency range, there is a requirement for electronic components (typically resin components), such as circuit boards, to have low dielectric constant and low dielectric loss tangent. To achieve this, it has been proposed, for example, to incorporate air with a low dielectric constant into the component. Specifically, as disclosed in Patent Document 1 and Patent Document 2, it has been proposed to introduce air using hollow particles. Prior art literature

[0003] International Release No. 2021 / 171858 International Release No. 2021 / 171859 The problem to be solved

[0004] With the recent increase in high speed and high capacity of information and communication devices, there is a demand for further improvement in the dielectric properties of hollow particles.

[0005] The present invention was made to solve the above problem, and one of its objectives is to provide hollow particles with improved dielectric properties. means of solving the problem

[0006] (1) The hollow particle of the present disclosure has a hollow shell inside. The shell is silica containing aluminum. The amount of aluminum is greater in the first portion than in the second portion. The first portion is located on the inner side in the thickness direction of the shell. The second portion is located on the outer side in the thickness direction of the shell compared to the first portion.

[0007] (2) In the hollow particles of the present disclosure, the aluminum content of the hollow particles described in (1) is less than 1% of the components constituting the shell.

[0008] (3) In the hollow particles of the present disclosure, the amount of aluminum present is reduced from the inner side of the shell toward the outer side.

[0009] (4) The hollow particles of the present disclosure, in the hollow particles described in any one of (1) to (3) above, have an epoxy resin oil absorption amount of less than 0.6 g / m².

[0010] (5) In the hollow particles of the present disclosure, the shells of the hollow particles described in any one of (1) to (4) further contain sodium. The sodium content of the shells is 3000 ppm or less.

[0011] (6) The hollow particles of the present disclosure are the hollow particles described in any one of (1) to (5), wherein the silica is amorphous silica.

[0012] (7) The hollow particles of the present disclosure, in the hollow particles described in any one of (1) to (6) above, have a hollowness of 30% or more and 95% or less.

[0013] (8) The hollow particles of the present disclosure, in the hollow particles described in any one of (1) to (7), have a shell thickness of 25 nm or more and 500 nm or less.

[0014] (9) The method for manufacturing a hollow particle of the present disclosure is a method for manufacturing a hollow particle described in any one of (1) to (8). The manufacturing method comprises obtaining a core-shell particle by coating a core particle with a shell-forming material, obtaining a hollow particle precursor by removing the core particle from the core-shell particle, and coating the hollow particle precursor with a shell-forming material.

[0015] (10) The method for manufacturing hollow particles of the present disclosure is the method for manufacturing hollow particles described in (9), wherein the core particle comprises an aluminate-type compound represented by the following general formula (I).

[0016]

[0017] In Equation (I), M is Na + , K + , NH4 + and H3O + It is at least one cation selected from the group consisting of . In formula (I), M' is Cu 2+ , Zn 2+ , Ni 2+ , Sn 4+ , Zr 4+ and Ti 4+ It is at least one cation selected from the group consisting of. In Equation (I), a satisfies 0.8 ≤ a ≤ 1.35. In Equation (I), m satisfies 0 ≤ m ≤ 5. In Equation (I), x satisfies 0 ≤ x ≤ 0.4. In Equation (I), y satisfies 1.7 ≤ y ≤ 2.5. In Equation (I), z satisfies 4 ≤ z ≤ 7. Effects of the invention

[0018] According to an embodiment of the present invention, excellent genetic properties can be achieved. Brief explanation of the drawing

[0019] Figure 1 is a schematic diagram illustrating the long diameter and short diameter. FIG. 2 is a cross-sectional view schematically showing a hollow particle in one embodiment of the present invention. Figure 3a is a graph showing a schematic example of the change in the amount of Al present in the thickness direction of the shell. Figure 3b is a graph showing a schematic representation of another example of the change in the amount of Al present in the thickness direction of the shell. Figure 3c is a graph showing a schematic representation of another example of the change in the amount of Al present in the thickness direction of the shell. FIG. 4 is a schematic cross-sectional view of a laminate in one embodiment of the present invention. Figure 5a is a TEM observation photograph of the hollow particles of Example 1. Figure 5b is a TEM observation photograph of the hollow particles of Example 2. Figure 5c is a TEM observation image of the hollow particles of Example 3. Figure 6 is a cross-sectional SEM image of the resin molded body of Example 1. Specific details for implementing the invention

[0020] Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

[0021] (Definition of Terms)

[0022] The definitions of terms in this specification are as follows.

[0023] 1. Long diameter of the particle

[0024] The long diameter of the particle is a value measured by a scanning electron microscope (SEM). The long diameter of the particle is the average value of the long diameters of randomly selected primary particles, as indicated by L in Fig. 1, for example. In addition, primary particles are the smallest particles observed from the SEM and are distinguished from aggregated secondary particles.

[0025] 2. Short diameter of the particle

[0026] The short diameter of the particle is a value measured by SEM observation. The short diameter of the particle is the average value of the short diameters of randomly selected primary particles, as indicated by T in Fig. 1, for example.

[0027] 3. Aspect B

[0028] The aspect ratio is a value calculated by dividing the short diameter of the particle by the long diameter of the particle.

[0029] A. Hollow particles

[0030] In one embodiment of the present invention, the hollow particle has a hollow shell inside. In other words, the hollow particle has a shell and a space enclosed by the shell. The shell contains silica. The silica is typically amorphous silica. The silica content of the shell is, for example, 95 weight% or more, preferably 97 weight% or more, and more preferably 98 weight% or more.

[0031] The shell of the above hollow particle contains aluminum (Al). By including Al, a hollow particle with excellent strength (breaking strength) can be obtained. The Al content is preferably 0.1% or more, and more preferably 0.2% or more. Meanwhile, the dielectric constant and dielectric loss tangent of the hollow particle tend to increase by including Al. Therefore, the Al content is preferably less than 1%, more preferably 0.9% or less, even more preferably 0.7% or less, and particularly preferably 0.5% or less. With this content, the hollow particle can have very excellent dielectric properties. The Al content can be determined, for example, by compositional analysis using inductively coupled plasma emission spectrometry (ICP-AES).

[0032] Hollow particles are formed such that the amount of Al is higher on the inner side in the thickness direction of the shell than on the outer side in the thickness direction. With this configuration, hollow particles with excellent strength (fracture strength), hollowness, and dielectric properties can be obtained. Specifically, the region of hollow particles with a high Al content is more prone to softening during sintering. In other words, hollow particles allow for a lower sintering temperature during the manufacturing process. Furthermore, due to the region with a high Al content, hollow particles can shrink more on the inner side than on the outer side of the hollow particle precursor constituting the shell during sintering. Hollow particles can increase fracture strength due to the region with a high Al content. Additionally, it is believed that hollow particles contribute to an improvement in the hollowness by maintaining the particle size through the softening shrinkage on the outer side of the shell, while expanding the internal space through the softening shrinkage on the inner side. In other words, hollow particles can improve shell strength and hollowness due to the different distribution of Al content between the outer and inner sides of the shell. Since the hollow particles have excellent strength and can also be low dielectric, the hollow particles can be effectively prevented from breaking when, for example, when producing a resin composition containing a resin and hollow particles. As a result, the hollow state of the particles is maintained, which can contribute significantly to the improvement of dielectric properties. In addition, if the shell thickness of the hollow particles is thin, Al is more likely to be uniformly distributed. For example, when Al is uniformly distributed in the hollow particles, the inner and outer sides of the shell shrink in the same way, and the particle size tends to decrease.

[0033] FIG. 2 is a cross-sectional view schematically illustrating a hollow particle in one embodiment of the present invention. In FIG. 2, the hatching of the cross-section of the hollow particle is omitted to make the drawing easier to view. The hollow particle (2) has a shell (4) and a space (hollow part) (6) surrounded by the shell (4). The amount of Al present in the first part (4a) located inward in the thickness direction of the shell (4) is greater than the amount of Al present in the second part (4b) located outward in the thickness direction compared to the first part (4a). In the case where the first portion (4a) of the hollow particle is located on or near the inner surface of the shell (4), as shown in FIG. 2, and the second portion (4b) is located on or near the outer surface of the shell, it is preferable that the amount of Al present in the first portion (4a) is at least twice the amount of Al present in the second portion (4b), and more preferable that it is at least three times. The distribution of the amount of Al present can be determined, for example, by compositional analysis using energy-dispersive X-ray spectroscopy (TEM-EDS) with a transmission electron microscope (TEM). In one embodiment, the amount of Al present can be evaluated as the molar ratio of Al to Si.

[0034] As an example of the distribution of Al content in the thickness direction, a form in which the Al content continuously decreases from the inner side of the shell toward the outer side can be cited. In this case, the method of changing the Al content is not particularly limited. For example, the Al content may decrease linearly with respect to the distance from the inner surface of the shell, as shown in FIG. 3a. In addition, as shown in FIG. 3b, it may decrease exponentially with respect to the distance from the inner surface of the shell. Specifically, the Al content of the hollow particles can be controlled by controlling the method of adding Al raw materials during the primary silica treatment of the core particles and the secondary silica treatment of the hollow particle precursor. When the Al content decreases linearly, the hollow particles tend to have a higher hollowness compared to the case where Al is uniformly distributed in the shell. When the Al content decreases exponentially, the hollow particles tend to have a higher hollowness compared to the case where it decreases linearly.

[0035] As another example of the distribution of Al content in the thickness direction, a form in which the Al content decreases in stages from the inner side of the shell toward the outer side can be cited. In other words, the hollow particle discontinuously decreases the Al content from the inner side of the shell toward the outer side. The hollow particle may be exemplified, for example as shown in FIG. 3c, having a first region (41) in which the Al content is constant from the inner surface of the shell toward the outer side, and a second region (42) in which the Al content is less than that of the first region (41) located further outward from the first region (41). Furthermore, in FIG. 3c, the first region (41) and the second region (42) are shown as linear for convenience, but the fact that the Al content is constant means, for example, that the variation in the Al content is 20% or less. Also, FIG. 3c shows an example in which the Al content decreases in two stages, but it may be three or more stages. Hollow particles can enhance the effect of improving strength and hollowness when the amount of Al present is gradually reduced.

[0036] The shell of the hollow particle may contain sodium (Na). If the Na content is too high, the hollow particle tends to shrink because it becomes difficult to raise the calcination temperature during the manufacturing process of the hollow particle. The Na content is preferably 3,000 ppm or less, more preferably 2,000 ppm or less, and even more preferably 1,500 ppm or less. On the other hand, the Na content is preferably 100 ppm or more. The Na content can be determined, for example, by compositional analysis using atomic absorption spectrometry (AAS).

[0037] In hollow particles, it is preferable that the amount of Na present is greater on the inner side in the thickness direction of the shell than on the outer side in the thickness direction. It is thought that in hollow particles, Na is easily incorporated to fill electron vacancies when some of the Si (4+) is substituted with Al (3+). Therefore, it is thought that in hollow particles, Na tends to be present in large amounts in regions where Al is abundant.

[0038] In one embodiment, the primary particle of the hollow particle is 1≤D SL It is desirable to satisfy ≤1.5. For the primary particles of the hollow particles, 1≤D SL By satisfying ≤1.5, fluctuations between particles can be suppressed, thereby promoting the homogenization of dielectric properties. For the primary particles of the hollow particles, 1≤D SL It is more desirable to satisfy ≤1.4, and 1≤D SL It is more desirable to satisfy ≤1.3. Here, D SL is D 75L / D 25L and, D 25L and D 75L Each represents the 25th and 75th values ​​when the long diameters of 100 randomly selected primary particles are measured and arranged in order from smallest to largest during observation by scanning electron microscope.

[0039] The primary particle of the hollow particle is, 1≤D ST It is desirable to satisfy ≤1.5, and more preferably 1≤D ST Satisfying ≤1.4, and more preferably 1≤D ST Satisfies ≤1.3. Here, D ST is D 75T / D 25T and, D 25T and D 75TEach represents the 25th and 75th values ​​when the short diameters of 100 randomly selected primary particles are measured during observation by scanning electron microscope and arranged in order from smallest to largest.

[0040] The aspect ratio of the above hollow particles is preferably less than 2, and more preferably 1.9 or less. Meanwhile, the aspect ratio of the hollow particles is 1 or more, preferably greater than 1, and more preferably 1.1 or more.

[0041] The hollow particles may have any suitable shape. Examples of shapes for the hollow particles include elliptical, spherical, aggregated, flaky, plate-like, membrane-like, cylindrical, prismatic, flat, stone-like, and rice-grain-like. Preferably, spherical or stone-like shapes are adopted for the hollow particles. By adopting such shapes, for example, the above D SL and D ST It can satisfy well.

[0042] The long diameter of the hollow particles is preferably 0.5 μm or more, and more preferably 1 μm or more. This is because, for example, if the long diameter of the hollow particles is 0.5 μm or more, the hollow ratio described below can be sufficiently satisfied. Meanwhile, the long diameter of the hollow particles is preferably 10 μm or less, and more preferably 5 μm or less. This is because, for example, if the long diameter of the hollow particles is 10 μm or less, it can significantly contribute to the miniaturization or thinning of the member used.

[0043] The short diameter of the hollow particles is preferably 0.25 μm or more, and more preferably 0.5 μm or more. This is because, for example, if the short diameter of the hollow particles is 0.25 μm or more, the hollow ratio described below can be sufficiently satisfied. Meanwhile, the short diameter of the hollow particles is preferably 10 μm or less, and more preferably 5 μm or less. This is because, for example, if the short diameter of the hollow particles is 10 μm or less, it can significantly contribute to the miniaturization or thinning of the member used.

[0044] The thickness of the shell of the hollow particle is preferably 25 nm or more, more preferably 50 nm or more, and even more preferably 75 nm or more. With this thickness, the hollow particle can be effectively prevented from breaking, for example, when producing a resin composition. Meanwhile, the thickness of the shell of the hollow particle is preferably 500 nm or less, more preferably 350 nm or less, and even more preferably 250 nm or less. With this thickness, the hollowness ratio described later can be sufficiently satisfied and can contribute significantly to the improvement of dielectric properties and weight reduction. In addition, the shell thickness can be measured by TEM observation. For example, it is obtained by measuring the shell thickness of randomly selected hollow particles and calculating the average value of the measured shell thicknesses. The shell thickness of the hollow particle may affect the distribution of the amount of Al present.

[0045] The hollowness of the hollow particles is preferably 30% or more, more preferably 40% or more, even more preferably 45% or more, and particularly preferably 50% or more. With such a hollowness, for example, it can significantly contribute to the improvement of dielectric properties and weight reduction. Meanwhile, the hollowness of the hollow particles is preferably 95% or less, more preferably 90% or less, even more preferably 85% or less, and particularly preferably 80% or less. With such a hollowness, for example, when producing a resin composition, the hollow particles can be effectively prevented from breaking. In addition, the hollowness can be calculated from the long diameter and short diameter and the thickness of the shell.

[0046] The BET specific surface area of ​​the hollow particles is preferably 30 m² / g or less, more preferably 20 m² / g or less, and even more preferably 10 m² / g or less. Meanwhile, the BET specific surface area of ​​the hollow particles is, for example, 0.5 m² / g or more, and may be 1 m² / g or more.

[0047] The cumulative pore volume of pores with a diameter of 1 nm to 100 nm is preferably 0.1 cc / g or less, more preferably 0.08 cc / g or less, and even more preferably 0.06 cc / g or less. With such a pore volume, for example in a resin composition, the intrusion of resin into the interior of the hollow particles can be effectively prevented, thereby contributing significantly to the improvement of dielectric properties. Meanwhile, the cumulative pore volume of pores with a diameter of 1 nm to 100 nm is, for example, 0.01 cc / g or more.

[0048] The cumulative pore volume of pores with a diameter of 1 nm to 10 nm is preferably 0.025 cc / g or less, more preferably 0.020 cc / g or less, and even more preferably 0.010 cc / g or less. With such a pore volume, for example in a resin composition, the intrusion of resin into the interior of the hollow particles can be effectively prevented, thereby contributing significantly to the improvement of dielectric properties. Meanwhile, the cumulative pore volume of pores with a diameter of 1 nm to 10 nm is, for example, 0.001 cc / g or more.

[0049] The density of the hollow particles is preferably 0.90 g / cc or less, and more preferably 0.80 g / cc or less. Meanwhile, the density of the hollow particles is preferably 0.55 g / cc or more, and more preferably 0.60 g / cc or more. With these densities, the hollow particles can achieve the maintenance of the shell strength and hollowness ratio.

[0050] The dielectric constant of the hollow particle at 25°C and 10 GHz is preferably 2.2 or less, and more preferably 2.0 or less. Meanwhile, the dielectric constant of the hollow particle at 25°C and 10 GHz is, for example, 1.0 or more. The dielectric loss tangent of the hollow particle at 25°C and 10 GHz is preferably 0.005 or less, and more preferably 0.002 or less. Meanwhile, the dielectric loss tangent of the hollow particle at 25°C and 10 GHz is, for example, 0.0001 or more.

[0051] The fracture strength of the hollow particles is preferably 10 MPa or higher, more preferably 12 MPa or higher, even more preferably 14 MPa or higher, and particularly preferably 16 MPa or higher. With this fracture strength, the hollow particles can be effectively prevented from breaking, for example, when producing a resin composition. As a result, the hollow state of the particles is maintained, which can significantly contribute to the improvement of dielectric properties. Meanwhile, the fracture strength of the hollow particles is, for example, 800 MPa or lower.

[0052] The fracture strength of hollow particles can be measured, for example, using a microcompression tester (the “MCT-510” manufactured by Shimadzu Seisakusho Co., Ltd.) with a measuring kit and a side observation kit. Specifically, the fracture strength can be measured by scattering a minute amount of hollow particles onto a lower pressure plate and performing a fracture test on each particle one by one under the following measurement conditions.

[0053] · Test force: 0.980 mN

[0054] · Load speed: 0.0223 mN / sec

[0055] · Upper pressure indenter: Flat φ20㎛

[0056] For example, measurements are taken on 10 particles, and the fracture strength Cs is calculated from the particle diameter d (mm) of each measured particle and the test force P (N) at the fracture point. To calculate the fracture strength Cs, the following formula from JIS R1639-5 “Method for Measuring Fine Ceramic Granule Characteristics - Part 5: Single Granule Crushing Strength” is used.

[0057] Cs=2.48P / πd 2

[0058] The fracture strength of the hollow particles can be obtained by calculating the average value of the fracture strength Cs (MPa) of 10 particles.

[0059] It is preferable that the epoxy resin oil absorption amount per 1g of hollow particle be 2.3g or less, and more preferably 2.0g or less. In addition, it is preferable that the epoxy resin oil absorption amount of the hollow particle be less than 0.6g / m², more preferably 0.46g / m² or less, and even more preferably 0.35g / m² or less.

[0060] In one embodiment, it is preferable that the hollow particles are surface-treated with any suitable surface treatment agent. As a surface treatment agent, at least one selected from the group consisting of, for example, higher fatty acids, anionic surfactants, cationic surfactants, phosphate esters, coupling agents, esters of polyhydric alcohols and fatty acids, acrylic polymers, and silicone treatment agents is used.

[0061] Any suitable method may be employed as the method for manufacturing the above-mentioned hollow particles. A method for manufacturing hollow particles according to one embodiment of the present invention comprises obtaining core-shell particles by coating a core particle with a shell-forming material, obtaining a hollow particle precursor by removing the core particle from the core-shell particles, and coating the hollow particle precursor with a shell-forming material. By coating the hollow particle precursor with a shell-forming material, a rigid shell can be formed, for example, while suppressing a decrease in the hollowness ratio. Specifically, the hollow particle precursor obtained by removing the core particle may have pores and may be in a brittle state. By filling the pores of the hollow particle precursor with a shell-forming material, a hollow particle having a rigid shell can be obtained without shrinking the hollow particle precursor. The shrinkage of the hollow particle precursor is, for example, softening shrinkage.

[0062] The above core particle is such that the primary particle is 1≤D SL It is desirable to satisfy ≤1.5, and more preferably 1≤D SL ≤1.4, more preferably 1≤D SL ≤1.3. Also, the primary particle of the core particle is 1≤D ST It is desirable to satisfy ≤1.5, and more preferably 1≤D ST ≤1.4, more preferably 1≤D ST ≤1.3. Also, D SL and D ST Regarding this, it is as described above.

[0063] The aspect ratio of the core particles is preferably less than 2, and more preferably 1.9 or less. Meanwhile, the aspect ratio of the core particles is 1 or more, preferably exceeds 1, and more preferably 1.1 or more. Examples of the shapes of the core particles include elliptical, spherical, aggregated massive, flaky, plate-like, membrane-like, cylindrical, prismatic, flat, stone-like, and rice-grain-like. Preferably, spherical or stone-like shapes are adopted as the shapes of the core particles.

[0064] The long diameter of the core particle is preferably 0.5 μm or more, and more preferably 1 μm or more. Meanwhile, the long diameter of the core particle is preferably 10 μm or less, and more preferably 5 μm or less. The short diameter of the core particle is preferably 0.25 μm or more, and more preferably 0.5 μm or more. Meanwhile, the short diameter of the core particle is preferably 10 μm or less, and more preferably 5 μm or less.

[0065] Any suitable material may be used as the forming material for the core particles. For example, a material containing aluminum may be used to satisfy the distribution of the amount of Al present in the hollow particles obtained. In one embodiment, the core particles are preferably formed from an aluminate-type compound represented by the following general formula (I).

[0066]

[0067] In Equation (I), M is Na + , K + , NH4 + and H3O + It is at least one cation selected from the group consisting of . In formula (I), M' is Cu 2+ , Zn 2+ , Ni 2+ , Sn 4+ , Zr 4+ and Ti 4+It is at least one cation selected from the group consisting of. In Equation (I), a satisfies 0.8 ≤ a ≤ 1.35. In Equation (I), m satisfies 0 ≤ m ≤ 5. In Equation (I), x satisfies 0 ≤ x ≤ 0.4. In Equation (I), y satisfies 1.7 ≤ y ≤ 2.5. In Equation (I), z satisfies 4 ≤ z ≤ 7.

[0068] As the shell-forming material, for example, an alkoxysilane represented by sodium silicate (Na2O·nSiO2) or tetraethoxysilane (Si(OCH2CH3)4) is used. In one embodiment, sodium silicate (water glass) is used. The presence of Na makes it easier to soften during the firing process described later, for example, which may facilitate the control of the firing temperature. The shell-forming material may contain Al. For example, when a coating treatment is performed on a core particle using the shell-forming material multiple times, the distribution of the amount of Al present in the hollow particle obtained may be satisfied by adjusting the concentration of Al in the shell-forming material used for each treatment.

[0069] The amount of coating by the shell-forming material can be adjusted by any suitable method. For example, the amount of coating is adjusted by controlling the pH value when coating is performed using a shell-forming material containing sodium silicate. Specifically, sodium silicate can be stable in a high pH range. For example, sodium silicate can be stable at a pH of 11 or higher. Therefore, by lowering the pH value, sodium silicate molecules can be condensed, allowing silica to be efficiently precipitated onto the core particles. Here, if the core particles contain the aluminate-type compound, the water slurry of the aluminate-type compound itself may exhibit acidity. The acidity of the water slurry of the aluminate-type compound itself is, for example, pH 3 to 5. Since the water slurry of the aluminate-type compound itself is acidic, silica can be efficiently precipitated onto the core particles without, for example, using a pH adjusting agent to lower the pH value. When a coating treatment is performed multiple times on a core particle containing an aluminate-type compound using a shell-forming material containing sodium silicate, a pH adjusting agent may be used in at least one of the multiple treatments. In this case, an acidic solution such as hydrochloric acid or sulfuric acid may be used as the pH adjusting agent. By using an acidic solution, hollow particles with a low Na content can be obtained.

[0070] In addition, coating by the shell-forming material can be promoted by heating when coating with the shell-forming material. Specifically, the shell formation rate can be increased by promoting the precipitation of the shell. The heating temperature when coating with the shell-forming material is, for example, 80°C to 90°C. In addition, the coating amount can be adjusted by controlling the concentration and mixing amount of the shell-forming material when coating. When coating core particles with a shell-forming material containing sodium silicate, the concentration of sodium silicate in the shell-forming material is, for example, 0.1 mol / L to 2 mol / L.

[0071] The removal of the core particles is typically performed by dissolving the core particles in an acidic solution. Examples of acidic solutions used are hydrochloric acid, sulfuric acid, and nitric acid. The dissolution temperature is, for example, 30°C to 90°C, and preferably 50°C to 80°C. At these temperatures, the core particles can be efficiently dissolved while suppressing problems such as the shell becoming brittle. In one embodiment, sulfuric acid is used as the acidic solution, for example, from the perspective of reusing the material obtained by reacting with the core particles. Examples of materials obtained by reacting with the core particles include salts. The concentration of sulfuric acid is, for example, 0.1 mol / L to 3.5 mol / L, and preferably 0.5 mol / L or higher. When dissolving core particles containing an aluminate-type compound, the Al content can be well achieved by adjusting, for example, the acidic solution, the dissolution temperature, and the time.

[0072] The method for manufacturing the above-described hollow particles may include calcining the core-shell particles before removing the core particles. If the core particles contain the aluminate-type compound, it is preferable to perform calcination before removing the core particles. It is preferable to perform calcination, for example, under an atmospheric environment. This is because, since the aluminate-type compound can possess acid resistance, the aluminate-type compound is altered by calcination, and the core particles after calcination become easily soluble in acidic solutions. Specifically, regarding the core particles containing the aluminate-type compound, the portion with low aggregation density is easily soluble in acidic solutions, but the portion with high aggregation density is difficult to dissolve in acidic solutions, and the amount of soluble in acidic solutions is limited to, for example, about 30% by weight. By calcination, aluminum oxide (Al2O3), which is easily soluble in acidic solutions, is generated from the aluminate-type compound, thereby improving the solubility of the core particles in acidic solutions.

[0073] The calcination temperature of the core-shell particles is, for example, 300°C to 900°C, and preferably 300°C to 650°C. At this calcination temperature, crystallization of the shell can be suppressed, thereby producing the aluminum oxide. The calcination time is, for example, 0.5 hours to 20 hours. The calcination may be performed continuously or in multiple stages at different temperatures. In addition, when the calcination is performed in multiple stages, the calcination time is the sum of the calcination times of each stage. In one embodiment, the distribution of the amount of Al present in the hollow particles obtained may be satisfied by adjusting the calcination temperature of the core-shell particles.

[0074] The shell-forming material used for coating the hollow particle precursor is preferably selected in correspondence with the shell-forming material used for coating the core particle. Specifically, when sodium silicate is used as the shell-forming material for coating the core particle, sodium silicate is preferably used as the shell-forming material for coating the hollow particle precursor.

[0075] When coating a hollow particle precursor with a shell-forming material containing sodium silicate, it is desirable to adjust the coating amount by controlling the pH value. Specifically, sodium silicate can be stabilized in a high pH range. A high pH range is, for example, pH 11 or higher. It is desirable to efficiently precipitate silica onto the hollow particle precursor by condensing sodium silicate molecules through, for example, lowering the pH value using a pH adjuster. As a pH adjuster, acidic solutions such as hydrochloric acid or sulfuric acid are used.

[0076] The above method for manufacturing hollow particles may include calcining a hollow particle precursor coated with a shell-forming material. Specifically, the calcination of the hollow particle precursor may be performed after coating the hollow particle precursor with a shell-forming material. By calcining the hollow particle precursor, hollow particles that can significantly contribute to the improvement of dielectric properties can be obtained. Specifically, the hydrophobicity of the surface of the hollow particle precursor can be improved. More specifically, the silanol groups on the surface of the hollow particle precursor can be converted into siloxanes. Additionally, hollow particles that are easy to blend or disperse in the resin when producing a resin composition can be obtained. Specifically, by appropriately shrinking the particles through calcination, the pores on the surface of the hollow particle precursor can be filled to prevent fusion between particles, thereby obtaining hollow particles with a smooth surface. By obtaining hollow particles with a smooth surface, for example, the above BET specific surface area and pore volume can be achieved favorably. In one embodiment, the distribution of the amount of Al present in the hollow particles obtained may be satisfied by adjusting the calcination temperature of the hollow particle precursor.

[0077] The calcination temperature of the hollow particle precursor is, for example, 300°C to 1300°C, preferably 700°C to 1300°C, and more preferably 900°C to 1300°C. At this calcination temperature, the hydrophobization can be achieved well. Furthermore, a high hollowness ratio can be achieved even when calcining at this calcination temperature. Specifically, by performing calcination on a hollow particle precursor in which the pores are filled by a coating of a shell-forming material, the hydrophobization can be achieved well while suppressing the shrinkage of the hollow particle precursor. The calcination time of the hollow particle precursor is, for example, 0.1 hours to 10 hours. The calcination may be performed continuously or in multiple stages at different temperatures. For example, it may be performed by calcining at a temperature T1 below 950°C, followed by calcination at a temperature T2 above 950°C. In this case, the difference between temperature T1 and temperature T2 (T2-T1) is preferably 150°C or higher, and more preferably 250°C or higher. In addition, when firing is performed in multiple stages, the firing time is the sum of the firing times of each stage.

[0078] The above method for manufacturing hollow particles may include performing an acid treatment on the hollow particle precursor before calcining the hollow particle precursor. The acid treatment is preferably performed using an acidic solution, such as hydrochloric acid or sulfuric acid. When sodium silicate is used as the shell-forming material, the hollow particle precursor may contain Na. By removing Na through the acid treatment, the calcination temperature of the hollow particle precursor can be set high, thereby allowing for the production of hollow particles that can significantly contribute to the improvement of dielectric properties.

[0079] In the above method for manufacturing hollow particles, it is preferable that the process of obtaining the core-shell particles includes a drying treatment. Specifically, when performing a coating treatment with a shell-forming material on the core particles multiple times, it is preferable to perform a drying treatment on the core particles coated with the shell-forming material, and then perform a coating treatment with the shell-forming material again. The drying temperature in the process of obtaining the core-shell particles is, for example, 90°C to 120°C. The drying time in the process of obtaining the core-shell particles is, for example, 3 hours to 24 hours. By including such a drying treatment, the above oil absorption amount can be achieved well, for example, regardless of whether a pH adjusting agent is used during coating with the shell-forming material.

[0080] In one embodiment of the present invention, the hollow particles are used as functional agents for resin materials. Hereinafter, a resin composition containing the hollow particles will be described.

[0081] B. Resin composition

[0082] A resin composition in one embodiment of the present invention comprises a resin and the hollow particles. In the resin composition, the hollow particles may maintain a good hollow state. Furthermore, in a resin molded article formed using the resin composition, the hollow particles may maintain a good hollow state.

[0083] The above resin may be any suitable resin selected depending on, for example, the use of the resin composition obtained. For example, the resin may be a thermoplastic resin or a thermosetting resin. Specific examples of the resin include epoxy resin, polyimide resin, polyamide resin, polyamideimide resin, polyetheretherketone resin, polyester resin, polyhydroxypolyether resin, polyolefin resin, fluoropolymer, liquid crystal polymer, and modified polyimide. These may be used individually or in combination of two or more types.

[0084] The content ratio of the hollow particles in the resin composition is preferably 0.1 weight% or more, and more preferably 0.5 weight% or more. Meanwhile, the content ratio is preferably 90 weight% or less, and more preferably 85 weight% or less.

[0085] In the resin composition, it is preferable to contain at least 0.5 parts by weight of hollow particles per 100 parts by weight of resin, and more preferably at least 1 part by weight. Meanwhile, it is preferable to contain 300 parts by weight or less of hollow particles per 100 parts by weight of resin, and more preferably 200 parts by weight or less.

[0086] The volume ratio of hollow particles in the resin composition is preferably 0.1% or more, and more preferably 0.5% or more. Meanwhile, the volume ratio of hollow particles in the resin composition is preferably 70% or less, and more preferably 60% or less. For example, this is because the processability when manufacturing the resin composition can be excellent.

[0087] The hollowness of the hollow particles in the resin composition is preferably 30% or more, more preferably 40% or more, even more preferably 45% or more, and particularly preferably 50% or more.

[0088] The resin composition may include optional components. Examples of optional components include a curing agent, a stress-reducing agent, a coloring agent, an adhesion enhancer, a release agent, a flow modifier, a defoaming agent, a solvent, and a filler. These may be used individually or in combination of two or more. In one embodiment, the resin composition includes a curing agent. The content of the curing agent is, for example, 1 to 150 parts by weight per 100 parts by weight of the resin.

[0089] Any suitable method may be employed as a method for producing the above resin composition. Specifically, the resin composition is obtained by dispersing the hollow particles in the resin by any suitable dispersion method. Examples of dispersion methods include dispersion by various stirrers such as homomixers, dispersers, and ball mills, dispersion by a rotating or orbiting mixer, dispersion by shear force using a three-axis roll, and dispersion by ultrasonic treatment.

[0090] The above resin composition typically becomes a resin molded article formed into a desired shape. For example, it becomes a resin molded article formed into a desired shape using a mold. When molding the resin molded article, any appropriate treatment may be performed on the resin composition. For example, the resin composition may undergo a curing treatment.

[0091] In one embodiment of the present invention, the resin composition becomes a resin layer included in a laminate. Hereinafter, a laminate having a resin layer formed of the resin composition will be described.

[0092] C. Laminate

[0093] FIG. 4 is a schematic cross-sectional view of a laminate in one embodiment of the present invention. The laminate (10) has 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 illustrated, the laminate (10) may include other layers. For example, a substrate may be included as other layers. The substrate may be laminated on one side of the resin layer (11). Specifically, the substrate may be placed on the side of the resin layer (11) where the metal foil (12) is not placed. A resin film is typically used as the substrate. Unlike the illustrated example, the laminate (10) may be configured such that a metal foil (12) is placed on the surface of a laminated structure comprising a plurality of resin layers (11). The laminate (10) may be configured such that a metal foil (12) is disposed on each side of a laminated structure comprising a plurality of resin layers (11). Additionally, the laminate (10) may be configured such that a combination of resin layers (11) and metal foils (12) is stacked in multiple layers. The laminate (10) can be used, for example, as a wiring circuit board. The metal foil (12) is formed in a predetermined shape to form, for example, a predetermined circuit wiring.

[0094] The thickness of the resin layer is, for example, 5 μm or more, preferably 10 μm or more. Meanwhile, the thickness of the resin layer is, for example, 100 μm or less, preferably 50 μm or less, more preferably 25 μm or less. With such a thickness, it is possible to sufficiently respond to, for example, the miniaturization of electronic components in recent years.

[0095] Any suitable metal may be used as the metal forming the above metal foil. Examples include copper, aluminum, nickel, chromium, and gold. These may be used individually or in combination of two or more types. The thickness of the metal foil is, for example, 2 μm to 35 μm.

[0096] Any suitable method may be employed as a method for manufacturing the above laminate. For example, the resin composition is coated onto the substrate to form a coated layer, and the metal foil is laminated onto this coated layer to obtain the laminate. In another specific example, the resin composition is coated onto the metal foil to form a coated layer to obtain the laminate. Typically, at any suitable timing, an energy imparting treatment, such as heating or light irradiation, is performed on the coated layer to cure the coated layer. When coating, the resin composition may be dissolved in any suitable solvent and used.

[0097] Examples

[0098] The present invention will be specifically described below by way of examples, but the present invention is not limited by these examples. Furthermore, unless otherwise specifically stated, the measurement method for each characteristic is as follows. Also, unless otherwise specifically stated, "%" and "ppm" are based on weight.

[0099] 1. Long diameter of the particle

[0100] The elongation of the particles was calculated by FE-SEM observation. Specifically, the elongation of 100 primary particles randomly selected from the SEM images of the particles was measured, and the arithmetic mean (average elongation) of the obtained measurements was calculated. In addition, the magnification of the SEM observation was set to 10,000 times.

[0101] 2. Short diameter of the particle

[0102] The short diameter of the particles was calculated by FE-SEM observation. Specifically, the short diameters of 100 primary particles randomly selected from the SEM images of the particles were measured, and the arithmetic mean (average short diameter) of the obtained measurements was calculated. In addition, the magnification of the SEM observation was set to 10,000 times.

[0103] 3. D SL and D ST

[0104] D by FE-SEM observation SL and D ST was calculated. Specifically, the long diameter was measured for each of the 100 primary particles randomly selected from the particle SEM images, and the 75th value (D 75L ) is the 25th value (D 25L Divide by ) and D SL ...was calculated. In addition, the short diameter was measured for each of the 100 primary particles randomly selected from the SEM images of the particles, and the 75th value (D 75T ) is the 25th value (D 25T Divide by ) and D ST It produced.

[0105] 4. Aspect B

[0106] The aspect ratio was calculated by FE-SEM observation. Specifically, the aspect ratio was calculated by dividing the average long diameter of the particle by the average short diameter of the particle.

[0107] [Example 1]

[0108] (Preparation of hollow silica particles)

[0109] Elliptical aluminate particle powder (NaAl3(SO4)2(OH)6, long diameter: 1.98㎛, D SL : 1.13, short diameter: 1.35㎛, D ST : 1.18, Aspect Ratio: 1.47) 800g was suspended in 5L of ion-exchanged water to obtain a slurry of aluminate particles.

[0110] Next, the obtained aluminate particle slurry was heated to 90°C while stirring, and 816 ml of No. 3 water glass (Na2O·2.97SiO2, manufactured by Fujifilm Wako Junyaku Co., Ltd.) at a concentration of 0.55 mol / L was added to it over a period of 4 hours. The slurry thus obtained was aged for 1 hour, then dehydrated and washed to obtain a cake of the first core-shell particle precursor. Subsequently, the cake of the first core-shell particle precursor was dried at 105°C for 1 day to obtain a core-shell particle powder.

[0111] Next, the powder of the first core-shell particle precursor was suspended in 5 L of ion-exchanged water and heated to 90°C while stirring, and 136 ml of No. 3 water glass at 0.55 mol / L was added over a period of 10 minutes. Subsequently, 680 ml of No. 3 water glass at 0.55 mol / L and 757 ml of sulfuric acid at 0.50 mol / L were added simultaneously. Here, the No. 3 water glass was added over a period of 50 minutes, and the sulfuric acid was added over a period of 60 minutes. The slurry thus obtained was aged for 30 minutes, then dehydrated and washed to obtain a cake of the second core-shell particle precursor.

[0112] The cake of the obtained second core-shell particle precursor was suspended in 5 L of ion-exchanged water and heated to 90°C while stirring. To this, 136 ml of No. 3 water glass at 0.55 mol / L was added over a period of 10 minutes. Subsequently, 680 ml of No. 3 water glass at 0.55 mol / L and 757 ml of sulfuric acid at 0.50 mol / L were added simultaneously. Here, the No. 3 water glass was added over a period of 50 minutes, and the sulfuric acid was added over a period of 60 minutes. The slurry thus obtained was aged for 30 minutes, dehydrated and washed with water, and then dried at 105°C for 1 day to obtain a core-shell particle powder.

[0113] Next, the obtained core-shell particle powder was calcined at 500°C for 3 hours, and additionally at 550°C for 1 hour. Furthermore, it is believed that the aluminate particles were changed as follows by calcination.

[0114] NaAl3(SO4)2(OH)6→NaAl(SO4)2+Al2O3+3H2O

[0115] Next, 6 L of ion-exchanged water was added to 737 g of calcined core-shell particles and resuspended under stirring at room temperature. Then, 3.95 L of sulfuric acid at a concentration of 2 mol / L was added to the mixture, heated to 90°C, and reacted for 5 hours to dissolve the core particles, thereby obtaining a slurry of the first hollow silica precursor. The first hollow silica precursor is also a hollow particle precursor. The obtained slurry of the first hollow silica precursor was dehydrated and washed with water to obtain a cake of the first hollow silica precursor.

[0116] Next, the obtained cake of the first hollow silica precursor (88 g of powder) was suspended in 4 L of ion-exchanged water and heated to 90°C while stirring. Then, 40 ml of No. 3 water glass at 0.55 mol / L was added over a period of 10 minutes, and subsequently, 200 ml of No. 3 water glass at 0.55 mol / L and 210 ml of sulfuric acid at 0.5 mol / L were added simultaneously. Here, the No. 3 water glass was added over a period of 50 minutes, and the sulfuric acid was added over a period of 60 minutes. The slurry thus obtained was aged for 30 minutes, and then dehydrated and washed to obtain the cake of the second hollow silica precursor.

[0117] Next, the obtained cake of the second hollow silica precursor was suspended in 4 L of ion-exchanged water and heated to 90°C while stirring. Then, 40 ml of water glass No. 3 with a concentration of 0.55 mol / L was added over a period of 10 minutes, after which 200 ml of water glass No. 3 with a concentration of 0.55 mol / L and 210 ml of sulfuric acid with a concentration of 0.50 mol / L were added simultaneously. Here, the water glass No. 3 was added over a period of 50 minutes, and the sulfuric acid was added over a period of 60 minutes. The slurry thus obtained was aged for 30 minutes, and then dehydrated and washed to obtain the cake of the third hollow silica precursor. In addition, the obtained cake of the third hollow silica precursor was suspended in 4 L of ion-exchanged water and heated to 90°C while stirring. Then, 40 ml of water glass No. 3 with a concentration of 0.55 mol / L was added over a period of 10 minutes, after which 200 ml of water glass No. 3 with a concentration of 0.55 mol / L and 210 ml of sulfuric acid with a concentration of 0.50 mol / L were added simultaneously. Here, the water glass No. 3 was added over a period of 50 minutes, and the sulfuric acid was added over a period of 60 minutes. The slurry thus obtained was aged for 30 minutes, and then dehydrated and washed to obtain the cake of the fourth hollow silica precursor.

[0118] Next, 2 L of ion-exchanged water and 1083 ml of 2 mol / L sulfuric acid were added to the obtained cake of the fourth hollow silica precursor (282 g of powder), and the mixture was left at 90°C for 1.5 hours to obtain a slurry of the fifth hollow silica precursor. Afterward, the cake obtained by dehydration and washing was dried at 105°C for 1 day to obtain the powder of the fifth hollow silica precursor.

[0119] Subsequently, the powder of the obtained fifth hollow silica precursor was calcined in an electric furnace at 800°C for 1 hour and at 1100°C for 1 hour to obtain hollow silica particles. Specifically, the powder of the fifth hollow silica precursor was calcined under an atmospheric environment to obtain hollow particles.

[0120] (Preparation of resin composition)

[0121] 95.2 phr of bisphenol F type epoxy resin ("JER806" manufactured by Mitsubishi Chemical Corporation) and 40 phr of obtained hollow silica particles were mixed for 3 minutes under atmospheric pressure, rotation at 1000 rpm, and revolution at 2000 rpm using a rotational mixer ("ARV-310P" manufactured by Shinki Corporation) to obtain a mixture. Hereinafter, the hollow silica particles may be referred to as fillers.

[0122] A resin composition was obtained by mixing the obtained mixture with 4.8 phr of an imidazole-based epoxy resin curing agent ("2E4MZ" manufactured by Shikoku Kasei Co., Ltd.) using a rotating-orbiting mixer for 3 minutes under conditions of rotation 1000 rpm, revolution 2000 rpm, and 0.7 kPa.

[0123] (Production of resin molded bodies)

[0124] The obtained resin composition was poured into a 1.0 mm thick Teflon (registered trademark) mold and press-molded at 80°C for 1 hour. After cooling, the molded body was removed from the mold and placed in a dryer at 150°C for 4 hours to further heat-cur it. Subsequently, the molded body was cooled to obtain an evaluation sample.

[0125] [Example 2]

[0126] (Preparation of hollow silica particles)

[0127] Elliptical aluminate particle powder (NaAl3(SO4)2(OH)6, long diameter: 1.98㎛, D SL : 1.13, short diameter: 1.35㎛, D ST : 1.18, Aspect Ratio: 1.47) 200g was suspended in 1.4L of ion-exchanged water to obtain a slurry of aluminate particles.

[0128] Next, the obtained aluminate particle slurry was heated to 90°C while stirring, and 202 ml of No. 3 water glass (Na2O·2.97SiO2, manufactured by Fujifilm Wako Junyaku Co., Ltd.) at a concentration of 0.56 mol / L was added to it over a period of 4 hours. The slurry thus obtained was aged for 1 hour, then dehydrated and washed to obtain a cake of the first core-shell particle precursor. Subsequently, the cake of the first core-shell particle precursor was dried at 105°C for 1 day to obtain a core-shell particle powder.

[0129] Next, the powder of the first core-shell particle precursor was suspended in 1.4 L of ion-exchanged water and heated to 90°C while stirring, and 34 ml of No. 3 water glass at 0.56 mol / L was added over a period of 10 minutes. Subsequently, 168 ml of No. 3 water glass at 0.56 mol / L and 188 ml of sulfuric acid at 0.51 mol / L were added simultaneously. Here, the No. 3 water glass was added over a period of 50 minutes, and the sulfuric acid was added over a period of 60 minutes. The slurry thus obtained was aged for 30 minutes, then dehydrated and washed to obtain a cake of the second core-shell particle precursor.

[0130] The cake of the obtained second core-shell particle precursor was suspended in 1.4 L of ion-exchanged water and heated to 90°C while stirring. To this, 34 ml of No. 3 water glass at 0.56 mol / L was added over a period of 10 minutes. Subsequently, 168 ml of No. 3 water glass at 0.56 mol / L and 188 ml of sulfuric acid at 0.51 mol / L were added simultaneously. Here, the No. 3 water glass was added over a period of 50 minutes, and the sulfuric acid was added over a period of 60 minutes. The slurry thus obtained was aged for 30 minutes, dehydrated and washed with water, and then dried at 105°C for 1 day to obtain a core-shell particle powder.

[0131] Next, the obtained core-shell particle powder was calcined at 500°C for 3 hours, and additionally at 550°C for 1 hour. Furthermore, it is believed that the aluminate particles were changed as follows by calcination.

[0132] NaAl3(SO4)2(OH)6→NaAl(SO4)2+Al2O3+3H2O

[0133] Next, 1305 ml of ion-exchanged water was added to 177 g of calcined core-shell particles and resuspended under stirring at room temperature. To this, 555 ml of sulfuric acid with a concentration of 3.35 mol / L was added, heated to 90°C, and reacted for 5 hours to dissolve the core particles, thereby obtaining a slurry of the first hollow silica precursor. The obtained slurry of the first hollow silica precursor was dehydrated and washed with water to obtain a cake of the first hollow silica precursor.

[0134] Next, the obtained cake of the first hollow silica precursor (18.8 g of powder) was suspended in 1.36 L of ion-exchanged water and heated to 90°C while stirring. Then, 20 ml of No. 3 water glass (0.56 mol / L) was added over a period of 10 minutes, and subsequently, 100 ml of No. 3 water glass (0.56 mol / L) and 105 ml of sulfuric acid (0.51 mol / L) were added simultaneously. Here, the No. 3 water glass was added over a period of 50 minutes, and the sulfuric acid was added over a period of 60 minutes. The slurry thus obtained was aged for 30 minutes, and then dehydrated and washed to obtain the cake of the second hollow silica precursor.

[0135] Next, the obtained cake of the second hollow silica precursor was suspended in 1.36 L of ion-exchanged water and heated to 90°C while stirring. Then, 20 ml of No. 3 water glass at 0.56 mol / L was added over a period of 10 minutes, after which 100 ml of No. 3 water glass at 0.56 mol / L and 105 ml of sulfuric acid at 0.51 mol / L were added simultaneously. Here, the No. 3 water glass was added over a period of 50 minutes, and the sulfuric acid was added over a period of 60 minutes. The slurry thus obtained was aged for 30 minutes, and then dehydrated and washed to obtain the cake of the third hollow silica precursor. In addition, the obtained cake of the third hollow silica precursor was suspended in 1.36 L of ion-exchanged water and heated to 90°C while stirring. Then, 20 ml of No. 3 water glass at 0.56 mol / L was added over a period of 10 minutes, followed by the simultaneous addition of 100 ml of No. 3 water glass at 0.56 mol / L and 105 ml of sulfuric acid at 0.51 mol / L. Here, the No. 3 water glass was added over a period of 50 minutes, and the sulfuric acid over a period of 60 minutes. The slurry thus obtained was aged for 30 minutes, and then dehydrated and washed to obtain the cake of the fourth hollow silica precursor.

[0136] Next, 1.36 L of ion-exchanged water and 146 ml of 3.35 mol / L sulfuric acid were added to the obtained cake of the fourth hollow silica precursor (52.8 g of powder), and the mixture was left at 90°C for 1.5 hours to obtain a slurry of the fifth hollow silica precursor. Afterward, the cake obtained by dehydration and washing was dried at 105°C for 1 day to obtain the powder of the fifth hollow silica precursor.

[0137] Next, the powder of the obtained fifth hollow silica precursor was calcined in an electric furnace (under an atmospheric atmosphere) at 800°C for 1 hour and at 1100°C for 1 hour to obtain hollow silica particles.

[0138] (Production of resin molded bodies)

[0139] A molded body (evaluation sample) was obtained in the same manner as in Example 1, except that the above hollow silica particles were used.

[0140] [Example 3]

[0141] (Preparation of hollow silica particles)

[0142] Elliptical aluminate particle powder (NaAl3(SO4)2(OH)6, long diameter: 1.98㎛, D SL : 1.13, short diameter: 1.35㎛, D ST : 1.18, Aspect Ratio: 1.47) 1500g was suspended in 7.5L of ion-exchanged water to obtain a slurry of aluminate particles.

[0143] Next, the obtained aluminate particle slurry was heated to 90°C while stirring, and 1507 ml of No. 3 water glass (Na2O·3.14SiO2, manufactured by Fujifilm Wako Junyaku Co., Ltd.) at a concentration of 0.54 mol / L was added to it over a period of 4 hours. After aging the slurry thus obtained for 1 hour, it was dehydrated and washed to obtain a cake of the first core-shell particle precursor.

[0144] Next, the cake of the obtained first core-shell particle precursor was suspended in 7.5 L of ion-exchanged water and heated to 90°C while stirring, and 1507 ml of No. 3 water glass with a concentration of 0.54 mol / L was added to this over a period of 2 hours. The slurry thus obtained was aged for 1 hour, left to stand for 15 hours while stirring, and then dehydrated and washed to obtain the cake of the second core-shell particle precursor. The cake of the obtained second core-shell particle precursor was suspended in 7.5 L of ion-exchanged water and heated to 90°C while stirring, and 1507 ml of No. 3 water glass with a concentration of 0.54 mol / L was added to this over a period of 2 hours. The slurry thus obtained was aged for 1 hour, left to stand for 15 hours while stirring, and then dehydrated and washed, and subsequently dried at 100°C for 1 day to obtain the core-shell particle powder.

[0145] Next, the obtained core-shell particle powder was calcined at 500°C for 3 hours, and additionally at 550°C for 1 hour. Furthermore, it is believed that the aluminate particles were changed as follows by calcination.

[0146] NaAl3(SO4)2(OH)6→NaAl(SO4)2+Al2O3+3H2O

[0147] Next, 6 L of ion-exchanged water was added to 864 g of calcined core-shell particles and resuspended under stirring at room temperature. Then, 7.8 L of sulfuric acid at 1 mol / L was added to the mixture, heated to 90°C, and reacted for 5 hours to dissolve the core particles, thereby obtaining a slurry of the first hollow silica precursor. The obtained slurry of the first hollow silica precursor was dehydrated and washed with water to obtain a cake of the first hollow silica precursor.

[0148] Next, the obtained cake of the first hollow silica precursor (130 g of powder) was suspended in 860 ml of ion-exchanged water and heated to 90°C while stirring. Then, 33 ml of No. 3 water glass (0.54 mol / L) was added over a period of 10 minutes. Subsequently, 163 ml of No. 3 water glass (0.54 mol / L) and 186 ml of sulfuric acid (0.50 mol / L) were added simultaneously; the No. 3 water glass was added over a period of 50 minutes, and the sulfuric acid over a period of 60 minutes. The slurry thus obtained was aged for 30 minutes, then dehydrated and washed to obtain the cake of the hollow silica precursor. The same operation was repeated two more times to obtain the cake of the second hollow silica precursor.

[0149] Next, 2 L of ion-exchanged water and 400 ml of sulfuric acid at 2.87 mol / L were added to the obtained cake of the second hollow silica precursor (284 g of powder), and the mixture was left at 90°C for 1.5 hours to obtain a slurry of the third hollow silica precursor. Afterward, the cake obtained by dehydration and washing was dried at 100°C for 1 day to obtain the powder of the third hollow silica precursor.

[0150] Subsequently, the powder of the third hollow silica precursor obtained was calcined in an electric furnace (under an atmospheric environment) at 800°C for 1 hour and at 1100°C for 1 hour to obtain hollow silica particles.

[0151] (Production of resin molded bodies)

[0152] A molded body (evaluation sample) was obtained in the same manner as in Example 1, except that the above-mentioned hollow silica particles were used and the amount of hollow silica particles was set to 25 phr. In addition, attempts were made to mix the hollow silica particles to have an amount equivalent to that of Example 1, but it was not possible to mix more than that.

[0153] [Comparative Example 1]

[0154] A molded body (evaluation sample) was obtained in the same manner as in Example 1, except that hollow silica particles were not incorporated.

[0155] <XRD 측정>

[0156] The hollow silica particles of Examples 1, 2, and 3 were analyzed by X-ray diffraction (using PANalytical’s “EMPYRIAN”) and were found to be amorphous silica.

[0157] <TEM-EDS 측정>

[0158] For the hollow silica particles of Examples 1, 2, and 3, a transmission electron microscope (JEM-2100PLUS manufactured by Nihon Denshi Co., Ltd.) and an energy-dispersive X-ray analyzer attached thereto (JED2300 series manufactured by Nihon Denshi Co., Ltd.) were used to introduce an image under conditions of an acceleration voltage of 200 kV and a magnification of 200,000 times, and compositional analysis was performed on three points in the thickness direction in point analysis mode.

[0159] The observation results of the hollow silica particles of Example 1 are shown in FIG. 5a, the observation results of the hollow silica particles of Example 2 are shown in FIG. 5b, and the observation results of the hollow silica particles of Example 3 are shown in FIG. 5c. In addition, the atomic ratios of oxygen (O), aluminum (Al), and silicon (Si) obtained from the obtained peak intensities are also shown. In all cases, a tendency was confirmed for the amount of Al to decrease from the inner side of the shell toward the outer side.

[0160] The following evaluation was also performed on the hollow silica particles of Examples 1, 2, and 3. The evaluation results are summarized in Table 1.

[0161] 1. Al content

[0162] The Al content was analyzed by preparing a sample for measuring Al content from hollow silica particles through pretreatment and analyzing it using inductively coupled plasma emission spectrometry (ICP-AES). Specifically, 250 mg of hollow silica particles were measured in a PMP resin beaker. Afterward, the hollow silica particles were soaked in ultrapure water, 3 ml of nitric acid and 5 ml of hydrofluoric acid were added and heated to dissolve them. After concentrating to 5 ml, a 1% aqueous boric acid solution was added, the remaining hydrofluoric acid was masked, and the mixture was inactivated to avoid damaging the analytical instrument and heated for 10 minutes. After cooling, the sample was diluted with ultrapure water to 50 ml to prepare a sample for measuring Al content, which was then provided for analysis.

[0163] From the obtained results, the Al content ratio was calculated.

[0164] 2. Na content

[0165] The Na content was analyzed by atomic absorption spectrometry (AAS) after preparing a sample for measuring Na content from hollow silica particles through pretreatment. Specifically, 250 mg of hollow silica particles were measured in a PMP resin beaker. Afterward, the hollow silica particles were soaked in ultrapure water, 3 ml of nitric acid and 5 ml of hydrofluoric acid were added and heated to dissolve them, then concentrated to 5 ml, a 1% aqueous boric acid solution was added, the remaining hydrofluoric acid was masked, and the mixture was inactivated to avoid damaging the analytical instrument and heated for 10 minutes. After cooling, the sample was prepared by diluting with ultrapure water to 50 ml to measure Na content and provided for analysis.

[0166] From the obtained results, the Na content ratio was calculated.

[0167] 3. Thickness of the hollow particle shell

[0168] The thickness of the particle shells was calculated by TEM observation. Specifically, the shell thickness of 10 primary particles randomly selected from the TEM images of the particles was measured, and the arithmetic mean (average thickness) of the obtained measurements was calculated. In addition, the magnification of the TEM observation was set to 10,000x and 100,000x.

[0169] 4. Hollow rate

[0170] The hollowness ratio was calculated from the above long diameter and short diameter and the thickness of the shell. Specifically, using the above primary particle diameter (long diameter, short diameter) and the thickness of the shell, the shape of the particle was approximated as a volume in the form of a cylinder, and the hollowness ratio was calculated by the following formula.

[0171] Hollowness = Volume of hollow region of hollow particle ÷ Volume of hollow particle × 100

[0172] Volume of a hollow particle = π × radius 2 ×Height = π × (Longest diameter ÷ 2) 2 × short diameter

[0173] Volume of the hollow region of a hollow particle = π × ((long diameter - shell thickness × 2) ÷ 2) 2×(short diameter - shell thickness × 2)

[0174] 5. BET specific surface area

[0175] The specific surface area was measured using Microtrack Bell Co., Ltd.'s "BELsorp-mini." Specifically, it was measured using the constant capacitance gas adsorption method with nitrogen gas, and the specific surface area was calculated through analysis using the BET multi-point method.

[0176] 6. Crafting Volume

[0177] The pore volume was measured using Microtrack Bell Co., Ltd.'s "BELsorp-max". Specifically, it was measured using a constant-capacitance gas adsorption method with nitrogen gas, and the pore volume (integrated pore volume of pores with a diameter of 1 nm to 100 nm and integrated pore volume of pores with a diameter of 1 nm to 10 nm) was calculated by analysis using the BJH method.

[0178] 7. Density

[0179] Density was determined by the nitrogen gas displacement method. Specifically, using a gas displacement density measuring device (Micromeritis, Accupic II 1340, dry automatic densimeter), 0.15 to 0.2 g of sample was collected in a 1 cm³ cell and measured using nitrogen gas. The measurement was repeated at least 5 times, and the average value was calculated.

[0180] 8. Permittivity and Dielectric Loss Tangent

[0181] The dielectric constant and dielectric loss tangent were measured using a dielectric constant measuring device for powders by the cavity resonance method. The measurements were taken at 10 GHz under conditions of a temperature of 25°C and a humidity of 44%RH. In addition, the density required for calculating the dielectric properties was the density value obtained by the nitrogen gas displacement method.

[0182] 9. Oil absorption

[0183] For 1g of hollow silica particles to be measured, epoxy resin ("JER819" manufactured by Mitsubishi Chemical Corporation) was added dropwise and mixed, and the amount of oil absorbed was calculated using the following conversion formula from the amount of epoxy resin added when it was transformed into a paste. Specifically, the addition and mixing of epoxy resin was repeated with respect to the hollow silica particles, and the point at which the hollow silica particles were transformed into a paste was defined as the endpoint. Dropping near the endpoint was performed by adding epoxy resin drop by drop. Subsequently, the amount of epoxy resin per 1g of the subject to be measured was calculated using the following formula, and the amount of oil absorbed per unit area (㎡) of the surface area was calculated by dividing the obtained amount of oil absorbed per 1g by the specific surface area of ​​the subject to be measured.

[0184] Oil absorption per 1g = Suitable amount of epoxy resin (g) / Mass of powder to be measured (g)

[0185] Oil absorption per unit area (m²) = Oil absorption per 1g (g / g) / Specific surface area of ​​the powder to be measured (m² / g)

[0186] <Evaluation of Resin Molded Body>

[0187] For the resin molded bodies (evaluation samples) of the Examples and Comparative Examples, density was measured, cross-sectional observation was performed, and dielectric properties were measured. In addition, the porosity of the resin molded bodies, the filler density in the resin molded bodies, and the filler hollowness ratio in the resin molded bodies were calculated. The evaluation results are summarized in Table 1. The results of observing the resin molded body of Example 1 at 2000x magnification are shown in Figure 6.

[0188] (Measurement of density)

[0189] The density of the resin molded body was measured using an electronic densimeter ("SD120L" manufactured by Alpha Mirage Co., Ltd.). Specifically, the obtained resin molded body was cut into a size of 5 cm × 6 cm using an ultrasonic cutter, and the molded body sample obtained by cutting was provided for measurement.

[0190] 1. Porosity of resin molded articles

[0191] From the measurement results of the above density, the porosity (ratio of the volume of air in the resin molded body) Va% of the resin molded body was calculated.

[0192] 2. Filler density in resin molded articles

[0193] The filler density in the resin molded body was calculated from the following formula. The filler density in the resin molded body was calculated by subtracting the volume of the resin component from the volume of the filler-containing resin molded body to determine the filler volume, and then dividing the filler addition amount by the calculated filler volume. The volume of the filler-containing resin molded body was measured using an electron densimeter ("SD120L" manufactured by Alpha Mirage Co., Ltd.). The volume of the resin component was calculated separately from the weight and density of a blank resin molded body produced without filler.

[0194] Filler density in resin molded articles = wf / (Vc-mr / ρr) = wf / (Vc-100 / ρr)

[0195] wf: Part by weight of particles (filler) when the weight of the resin is 100 parts by weight (phr).

[0196] Vc: Volume of the resin molded body

[0197] mr: Weight of resin (g)

[0198] ρr: Density of resin (g / ml)

[0199] 3. Filler hollowness in resin molded articles

[0200] From the value of the porosity Va% of the above resin molded article, the filler hollowness Va / (Va+Vs) in the resin molded article was calculated. Here, Vs can be obtained from the following formula.

[0201]

[0202] Vc: Volume of the resin molded body

[0203] Vs: Volume of the particle shell

[0204] Va: Volume of air in a resin molded article

[0205] Vr: Volume of resin

[0206] mc: Weight of resin molded body (g)

[0207] ρc: Density of resin molded body (g / ml)

[0208] ms: Weight of particle (shell) (g)

[0209] ρs: Density of the particle shell (2.28 (g / ml))

[0210] mr: Weight of resin (g)

[0211] ρr: Density of resin (g / ml)

[0212] wf: Parts by weight (phr) of particles (filler) when the weight of the resin is 100 parts by weight (phr)

[0213] (Observation of cross-section of resin molded body)

[0214] The obtained molded body sample was cut with a cross-section polisher ("IB-09010CP" manufactured by Nihon Denshi Co., Ltd.) and the cross-section was observed with an FE-SEM ("JSM-7600F" manufactured by Nihon Denshi Co., Ltd., magnification: 2000x, 5000x, or 10000x).

[0215] (Measurement of permittivity and dielectric loss tangent)

[0216] The dielectric constant and dielectric loss tangent of the obtained molded body samples were measured under the following conditions.

[0217] · Measurement method: Based on IEC 62810 (cavity resonator perturbation method)

[0218] · Sample shape: Length 55 mm or more, width 1.6 to 2.4 mm, height 0.7 to 1.0 mm

[0219] · Test conditions: Frequency 10 GHz

[0220] · Measurement count: 2 times

[0221] · Condition control: 23℃±1℃, 50%RH±5%RH, 24 hours

[0222] · Laboratory environment: 23℃±1℃, 50%RH±5%RH

[0223] · Measurement device: PNA Network Analyzer N5222B (Keysight Technologies Co., Ltd.)

[0224] · Cavity Resonator: CP531 for 10 GHz (Manufactured by Kanto Denshi Oyo Kaihatsu Co., Ltd.)

[0225]

[0226] In each example, as shown in FIG. 6, by observing the cross-section of the resin molded body, no intrusion of resin into the hollow region was confirmed, and it was confirmed that the destruction of the hollow particles was suppressed. In Examples 1 and 2, which have low oil absorption, it was possible to incorporate more filler into the resin, and it was found that the dielectric properties of the resin composition (resin molded body) were superior. Industrial applicability

[0227] The hollow particles of the present invention can be suitably used, for example, in electronic materials. In addition, they can be used, for example, in thermal insulation materials, soundproofing materials, shock-absorbing materials, stress-absorbing materials, optical materials, and lightweight materials. Explanation of the symbols

[0228] L: Long diameter T: Short diameter 2: Hollow particles 4: Shell 6: Space (Hollow section) 10: Laminate 11: Resin layer 12: Metal foil

Claims

Claim 1 A hollow particle having a hollow shell inside, wherein the shell is made of silica containing aluminum, the aluminum content is less than 1 weight percent of the components constituting the shell, and further wherein the amount of aluminum present is at least twice as much in a first portion located on the inner side in the thickness direction of the shell than in a second portion located near the surface on the outer side in the thickness direction of the shell. Claim 2 A hollow particle according to claim 1, wherein the amount of aluminum present decreases from the inner side to the outer side of the shell. Claim 3 A hollow particle according to paragraph 2, wherein the amount of aluminum present decreases continuously from the inner side to the outer side of the shell, or the amount of aluminum present decreases stepwise from the inner side to the outer side of the shell. Claim 4 In paragraph 1, a hollow particle having an epoxy resin oil absorption capacity of less than 0.6 g / m². Claim 5 In claim 1, the shell is a hollow particle that additionally contains sodium, and the sodium content of the shell is 3000 ppm or less. Claim 6 In claim 1, the silica is a hollow particle that is amorphous silica. Claim 7 In claim 1, the shell is a hollow particle having a hollowness ratio of 30% or more and 95% or less. Claim 8 A hollow particle according to claim 1, wherein the thickness of the shell is 25 nm or more and 500 nm or less. Claim 9 A method for manufacturing a hollow particle as described in any one of claims 1, 2, and 4 to 8, comprising: obtaining a core-shell particle by coating a core particle with a shell-forming material; obtaining a hollow particle precursor by removing the core particle from the core-shell particle; and coating the hollow particle precursor with a shell-forming material. Claim 10 A method of manufacturing according to claim 9, wherein the core particles comprise an aluminate-type compound represented by the following general formula (I): In Equation (I), M is Na + , K + , NH4 + and H3O + It is at least one cation selected from the group consisting of, and M' is Cu 2+ , Zn 2+ , Ni 2+ , Sn 4+ , Zr 4+ and Ti 4+ At least one cation selected from the group consisting of, a 0.8≤a≤1.35, m 0≤m≤5, x 0≤x≤0.4, y 1.7≤y≤2.5, and z 4≤z≤7.

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