Spherical crystalline silicon dioxide particles and their manufacturing method, as well as resin composites and resin composites containing the same.

Abstract

The purpose of this invention is to provide spherical crystalline particles with low lithium content and high quartz crystallinity, a method for manufacturing the same, and a resin composite composition and resin composite containing the spherical crystalline silica particles. This invention relates to spherical crystalline silica particles and a method for manufacturing the same, wherein the spherical crystalline silica particles have a roundness of 0.80 or higher, an average particle size (D50) of 1.0 μm or higher and 100.0 μm or lower, contain less than 0.05% by mass of lithium (in oxide terms), contain 0.10% to less than 1.00% by mass of calcium (in oxide terms), and comprise more than 50.0% of crystalline silica, of which more than 90.0% is quartz.

Description

Spherical crystalline silicon dioxide particles and their manufacturing method, as well as resin composites and resin composites containing the same. Invention Field This invention relates to spherical crystalline silica particles, particularly spherical crystalline silica particles with low lithium content and high quartz crystallinity, a method for manufacturing the same, and resin composite compositions and resin composites comprising the spherical crystalline silica particles. Background of the Invention Silicon dioxide particles are used as fillers in resins, such as as sealants for semiconductor devices. Regarding the shape of the silicon dioxide particles, angular shapes result in poor flowability, dispersibility, and filling properties in the resin. To improve this, spherical silicon dioxide particles are widely used. Generally, the spraying method is used to produce spherical silicon dioxide. In spraying, particles are passed through a high-temperature region, such as a flame, where they melt and their shape is spherical due to surface tension. The molten, spherical particles are then transported and recovered by a gas stream to prevent them from fusing together. The sprayed particles are then rapidly cooled. Because of this rapid cooling from the molten state, silicon dioxide contains almost no crystals and has an amorphous (non-crystalline) structure, becoming the glassy particles commonly known as quartz glass. Because the spherical silicon dioxide obtained by melt spraying is amorphous, its thermal expansion coefficient and thermal conductivity are low. It is conceivable that these properties are the same as the thermal expansion coefficient of quartz glass with an amorphous structure, which is roughly estimated to be 0.5 ppm / K and thermal conductivity 1.4 W / mK. Spherical silicon dioxide particles, commonly used in sealants, are amorphous and therefore have a low coefficient of thermal expansion. When mixed with resin, they reduce the coefficient of thermal expansion of the mixture (resin composition). This allows the coefficient of thermal expansion of the resin composition to approach that of semiconductor devices. Furthermore, when used in sealants, the resin composition suppresses deformation caused by heating and cooling during resin curing. However, amorphous silicon dioxide has relatively low thermal conductivity. On the other hand, the increasing performance of semiconductors is accompanied by increased heat generation, requiring more efficient heat dissipation. Therefore, spherical silicon dioxide particles with higher thermal conductivity are essential. Compared to amorphous silica, crystalline silica has a regular and dense structure, resulting in high thermal conductivity. Examples of crystalline silica include cristobalite, quartz, and tridymite. These crystalline silicas are known to have higher coefficients of thermal expansion and thermal conductivity compared to amorphous silica. Quartz, in particular, has a more dense crystalline structure than other crystals, resulting in a thermal conductivity as high as 12.8 W / mK. It is conceivable that spherical silica particles containing a greater amount of quartz can achieve even higher thermal conductivity. Various studies have been conducted to date on methods for obtaining crystalline silicon dioxide particles. Patent document 1 discloses a method of adding a Zn compound to an amorphous silica gel manufactured by the sol-gel method and then subjecting it to heat treatment at 900~1100℃ to obtain a SiO2-based silica gel. The powder is a porous material with 2 as the main component, containing Zn compounds, and whose main crystalline phase is quartz. The heat treatment was carried out in the atmosphere without any special pressure. Furthermore, the proportions of the crystalline phases are not disclosed. Patent Document 2 discloses a spherical crystalline silicon dioxide particle comprising at least 90% by mass of the crystalline phase, at least 70% by mass of the quartz crystal, and containing 0.4-5% by mass of lithium (in oxide terms) and / or 1-5% by mass of calcium (in oxide terms). This spherical crystalline silicon dioxide particle is obtained by heat-treating raw material powder at 800-1300°C and then cooling it. Furthermore, this heat treatment is carried out in an electric furnace, gas furnace, or similar facility without any special pressure. Patent Document 3 relates to spherical crystalline silicon dioxide particles, revealing that the proportion of crystalline silicon dioxide phase in these particles is 40.0% or more, and the quartz content in the crystalline silicon dioxide phase is 80.0% or more by mass. The particles contain lithium (0.02% to 0.40% by mass in oxide form) and calcium (0.004% to 1.0% by mass in oxide form). These spherical crystalline silicon dioxide particles are obtained by heat-treating raw material powder at 850-1150°C. Furthermore, this heat treatment is carried out in a gaseous environment containing inactive gases such as nitrogen and argon. From the viewpoint of industrial and large-scale heat treatment, atmospheric pressure is preferred, and no special pressurization is required. Patent Document 4 relates to a dental hardener, disclosing that the silica content of the spherical crystal control powder contained in the dental hardener is 97% to 100% by mass, and that the amorphous and crystalline portions are mixed. The ratio of the amorphous to the crystalline portion is controlled by heat-treating the amorphous raw material powder at 600°C to 1700°C. Furthermore, this heat treatment does not involve any special pressure. Patent Document 4 describes that pressure can be applied during hardening, but does not specify the exact pressure. Also, there are no particular limitations on the type and proportion of crystals. Patent Document 5 discloses a powder for use as a spherical silica filler containing more than 80% by mass of tetragonal silica phase. Tetragonal silica is not a typical crystalline phase like quartz or squartz silica; it is primarily synthesized under high temperature, high pressure, and high vapor pressure. In Patent Document 5, spherical amorphous silica particles are mixed with a lithium compound without special pressure, and the mixture is heated at 650-725°C for 3-20 hours to obtain the spherical silica filler powder. (Prior Art Documents Patent Documents) [Patent Document 1] Japanese Patent Application Publication No. 2002-20111 [Patent Document 2] International Publication No. 2018 / 186308 [Patent Document 3] International Publication No. 2021 / 235530 [Patent Document 4] Japanese Patent Application Publication No. 5616672 [Patent Document 5] Japanese Patent Application Publication No. 2019-52051 Invention Summary Problem to be Solved by the Invention For semiconductor products, it is essential to dissipate the generated heat efficiently. In particular, to cope with the increased heat generation associated with higher performance, peripheral components such as semiconductor sealing materials require highly thermally conductive materials that facilitate heat dissipation. Therefore, spherical crystalline silicon dioxide, which offers high thermal conductivity and high filler content, is highly useful as a filler material for sealing materials. Silicon dioxide exists in various crystalline forms, with quartz being particularly advantageous due to its high thermal conductivity. One method for obtaining spherical crystalline silicon dioxide involves adding elements to amorphous spherical silicon dioxide to promote crystallization and then heat-treating it at high temperatures to crystallize it. However, generally speaking, adding elements may affect the properties of the spherical crystalline silicon dioxide. Particularly for applications as semiconductor sealing fillers, there are concerns that alkali metals may impair the reliability of electronic devices. Therefore, for spherical crystalline silicon dioxide, further reduction of lithium is required. Furthermore, from the perspective of improving thermal conductivity, for spherical crystalline silicon dioxide, a certain level of crystalline content is required. This is because if the amorphous content is high, the thermal conductivity will become similar to that of amorphous silicon dioxide, and the overall thermal conductivity cannot be significantly improved. Moreover, the type of primary crystalline material must be limited. The thermal conductivity characteristics will differ depending on the type of crystalline material. Therefore, if multiple types of crystalline materials are mixed, the thermal conductivity will vary, and it may be impossible to obtain the desired thermal conductivity. Patent documents 1 and 4 do not specify the content or type of crystals. Furthermore, while patent document 5 discloses a silica-filled powder with a tetragonal silica phase content of 80% by mass, the content of the crystalline phase in this powder is unknown. Therefore, these prior art techniques may fail to achieve sufficient thermal conductivity. In the spherical crystalline silicon dioxide particles of Patent Document 2, the crystalline phase comprises more than 90% by mass, and the quartz crystals comprise more than 70% by mass, thus indicating sufficient thermal conductivity. However, it contains 0.4 to 5% by mass of lithium in terms of oxide content. In the spherical crystalline silicon dioxide particles of Patent Document 3, by containing more than 0.004% by mass and less than 1.0% by mass of calcium in terms of oxide content, the lithium content is reduced to more than 0.02% by mass and less than 0.40% by mass in terms of oxide content. However, further reduction of lithium content would be more ideal. In view of the above, the object of the present invention is to provide spherical crystalline particles with low lithium content and high quartz crystallinity, a method for manufacturing the same, and a resin composite composition and resin composite containing the spherical crystalline silica particles. Means for solving the problem The inventors, through repeated and in-depth research to solve the aforementioned problems, arrived at the following idea. Adding calcium to amorphous silica particles and then heat-treating them promotes crystallization into quartz. That is, calcium is a promoting element for quartz crystallization. However, quartz crystallization only occurs around the presence of calcium. In other words, the quartzization effect brought about by adding calcium is localized or limited. Furthermore, when amorphous silica particles are crystallized by heat treatment, crystallization into cuboidal silica generally also occurs. Therefore, in areas where the effect of calcium addition is limited, typically, crystallization into cuboidal silica rather than quartz occurs within the amorphous silica particles. To promote the overall quartzization of amorphous silica particles, it is necessary for calcium to thermally diffuse within the particles; however, the diffusion coefficient of calcium in amorphous silica is small. As a result, if only calcium is added, the quartz crystallization rate is low. This is particularly evident with large-diameter silica particles (typically D50: 10 μm and above). This is because the larger the diameter of the silica particles, the lower the specific surface area, and the smaller the contact area with calcium. Thus, there is a limit to how much calcium can be added to improve the crystallinity of quartz. On the other hand, it is known that pressure affects the crystallization of amorphous silica, but there are almost no detailed reports on this. Therefore, the inventors of this patent conducted crystallization experiments by changing the type and amount of additives added to amorphous silica particles and the gas environment pressure during heat treatment. In particular, regarding the gas environment pressure, a hot isostatic pressing (HIP) device was used to change it to a high-pressure region during high-pressure, high-temperature treatment. As a result, it was found that the amount of lithium added could be reduced to virtually zero while obtaining silica with a high quartz crystallinity. The gist of the present invention is as follows. [1] A spherical crystalline silicon dioxide particle having a sphericity of 0.80 or more, an average particle size (D50) of 1.0 μm or more and 100.0 μm or less, containing lithium of 0.05% by mass (in oxides) or less, containing calcium of 0.10% to less than 1.00% by mass (in oxides), comprising 50.0% or more of crystalline silicon dioxide, and comprising 90.0% or more of the aforementioned crystalline silicon dioxide as quartz. [2] The spherical crystalline silicon dioxide particle of [1] containing lithium of 0.02% by mass (in oxides). [3] The spherical crystalline silicon dioxide particle of [1] or [2] wherein scabbardite comprises 5.0% or less of the total. [4] The spherical crystalline silicon dioxide particle of any one of [1] to [3] containing 90 to 9000 ppm aluminum. [5] The spherical crystalline silicon dioxide particles of any of [1] to [4] have an average particle size (D50) of more than 10.0 μm. [6] A method for manufacturing spherical crystalline silica particles, comprising: a raw material powder adjustment step: mixing calcium raw material or calcium raw material and lithium compound particles into spherical amorphous silica particles to obtain raw material powder; and a heat treatment step: subjecting the raw material powder obtained in the aforementioned raw material powder adjustment step to a temperature of 1125°C or higher and 1300°C or lower and a pressure of 125 MPa or higher using a hot isostatic pressing apparatus for more than 1 hour to generate spherical crystalline silica particles; wherein the spherical crystalline silica particles generated in the aforementioned heat treatment step are adjusted such that calcium is 0.10 to 1.00% by mass in terms of oxides and lithium is 0.05% by mass or less in terms of oxides, and the mixing ratio of calcium raw material or calcium raw material and lithium compound particles in the aforementioned raw material powder adjustment step is adjusted. [7] A resin composite composition, characterized in that the resin contains spherical crystalline silica particles as described in any one of [1] to [5]. [8] A resin composite, characterized in that it is formed by curing a resin composite composition as described in [7]. Effects of the Invention According to the present invention, a spherical crystalline particle with low lithium content and high quartz crystallization rate can be provided, as well as a method for manufacturing the same, and a resin composite composition and resin composite comprising the spherical crystalline silicon dioxide particles. Forms used to implement inventions The spherical crystalline silicon dioxide particles of this invention are characterized by: a sphericity of 0.80 or higher; an average particle size (D50) of 1.0 μm or higher and 100.0 μm or lower; the presence of lithium at a mass percentage of 0.05% or less (in oxide terms); the presence of calcium at a mass percentage of 0.10% to less than 1.00% (in oxide terms); and a total content of 50.0% or more being crystalline silicon dioxide; wherein 90.0% or more of the aforementioned crystalline silicon dioxide is quartz. Each of these limitations will be explained below. The spherical crystalline silicon dioxide particles of this invention are spherical, and the method for forming the spherical shape is not particularly limited; crushing, grinding, and other methods can be used. In particular, the method of melt spraying before crystallization can achieve sphericalization with high productivity and low cost. When used as a filler in semiconductor sealing materials, the spherical silicon dioxide particles have high fluidity, dispersibility, and filling properties, and can also suppress wear on the machinery used in the manufacture of sealing materials. (Roundness: 0.80 or higher) More specifically, the average roundness of the spherical crystalline silicon dioxide particles of the present invention is 0.80 or higher, preferably 0.85, and more preferably 0.90 or higher. Roundness can be measured using a commercially available flow cytometry particle imager. A roundness of 1 indicates a true circle. That is, the closer the roundness is to 1, the closer it is to a true circle. The average roundness is calculated by averaging the roundness of at least 100 particles. If the average roundness is less than 0.80, when used as a filler for semiconductor sealing materials, there may be insufficient flowability, dispersibility, or filling capacity, or it may cause wear on the sealing material manufacturing machinery. The upper limit of roundness can be 1.0, but in practice, achieving a roundness of 1.0 is substantially difficult, and if implemented, manufacturing and management costs would increase. The upper limit of roundness can be set to 0.98, preferably 0.95, depending on the application. To achieve the aforementioned roundness, this can be achieved by adjusting the roundness of the amorphous spherical silica particles (particles before crystallization) used as the starting material. Highly spherical particles can be easily formed from silica powder using a melt spraying method. Furthermore, the average roundness of the spherical crystalline silica particles of this invention hardly decreases before and after the heat treatment used for crystallization. This is because the spherical crystalline silica particles of this invention form crystals at 1125~1300℃, and their roundness hardly decreases within this temperature range. Also, amorphous silica particles may fuse or sinter together at around 1125~1300℃; however, the spherical crystalline silica particles of this invention are already crystalline (no longer amorphous), effectively suppressing the fusion or sintering that occurs at around 1125~1300℃. If bonding occurs, the roundness will decrease, but because the bonding of the spherical crystalline silicon dioxide particles of the present invention is sufficiently suppressed, the average roundness hardly decreases. Therefore, when the spherical crystalline silicon dioxide particles of the present invention are used as fillers for semiconductor sealing materials, their flowability, dispersibility, and filling properties can be improved. (Average particle size (D50): 1.0 μm or more and 100.0 μm or less) The average particle size (D50) of the spherical crystalline silicon dioxide particles of the present invention is 1.0 to 100.0 μm, or may be 10.0 μm or more. If the average particle size exceeds 100.0 μm, when used as a filler for semiconductor sealing materials, the excessively large particle size may easily cause gate blockage or mold wear; if the average particle size is less than 1.0 μm, the particles are too small, which may cause the viscosity of the resin composition formed by mixing silicon dioxide particles with resin to increase excessively, making it impossible to fill in large quantities. Furthermore, the average particle size referred to here can be obtained by measuring the particle size distribution using wet laser diffraction (laser diffraction scattering method). The average particle size mentioned here is called the median particle size, which is the particle size that accumulates to 50% of the particle size frequency when the particle size distribution is measured by laser diffraction method, and is taken as the average particle size (D50). Within the aforementioned particle size range, this can be achieved by adjusting the particle size of the amorphous spherical silica particles (particles before crystallization) used as raw materials. The particle size can be easily adjusted using a melt spraying method. In other words, the average particle size of the spherical crystalline silica particles of this invention remains almost unchanged before and after the heat treatment used for crystallization. Amorphous silica particles tend to soften and fuse or sinter together at around 1125-1300°C; however, the spherical crystalline silica particles of this invention are already crystalline and do not soften like amorphous particles, thus effectively suppressing bonding due to melting or sintering at around 1125-1300°C. In particular, bonding caused by the melting or sintering of particles is more likely to occur with a larger particle surface area ratio, i.e., a smaller particle size. However, because the spherical crystalline silica particles of this invention are crystalline, even with an average particle size of 1.0 μm, they do not fuse or sinter together and are not prone to agglomeration. Therefore, when used as fillers in semiconductor sealing materials, the spherical crystalline silica particles of this invention can improve fluidity, dispersibility, and filling properties. Furthermore, the temperature at which particles fuse or sinter together varies depending on the particle size of the amorphous spherical silica in the raw material or the type and amount of additives. Therefore, even within the temperature range of 1125~1300°C, it is ideal to perform heat treatment at an appropriate temperature that does not result in melting or sintering, depending on the individual raw materials or additives. (Lithium content: less than 0.05% by mass in oxide conversion) The spherical crystalline silicon dioxide particles of this invention contain lithium at a rate of less than 0.05% by mass in oxide conversion, based on the total mass of the spherical crystalline silicon dioxide particles. Lithium is an alkali metal, and alkali metals can impair the reliability of electronic devices. Therefore, the lower the lithium content of the silicon dioxide particles, the higher the reliability of electronic devices using these silicon dioxide particles as fillers. From this perspective, a lower lithium content is better, which, in oxide conversion, can be less than 0.03% by mass, less than 0.03% by mass, less than 0.02% by mass, or less than 0.02% by mass, or less than 0.01% by mass. Furthermore, there is no lower limit to the lithium content; it can also be 0. The lithium in this invention is not limited to actively added substances; it can also be impurities contained in amorphous silicon dioxide particles or other raw materials. Furthermore, to adjust the lithium content, lithium or lithium compounds can be mixed with amorphous silicon dioxide particles or the like as raw materials. The lithium compound can be an oxide, carbon oxide, hydroxide, nitrogen oxide, etc., and its form is not particularly limited. Generally, lithium in silicon dioxide particles with promoted crystallization can exist in the form of oxides, carbon oxides, hydroxides, nitrogen oxides, or composite oxides with silicon dioxide, but it is mostly present in the form of oxides. Therefore, unless otherwise stated, in this invention, the lithium content is calculated using oxide conversion. Specifically, the lithium content is determined by ICP mass analysis (ICP-MS) and then converted to oxide content. (Calcium content: 0.10% by mass or more and less than 1.00% by mass in oxide form) The spherical crystalline silica particles of this invention contain calcium at a concentration of 0.10% by mass or more and less than 1.00% by mass in oxide form, based on the total mass of the spherical crystalline silica particles. Calcium promotes the crystallization of amorphous silica when heated together with it. If the calcium content is less than 0.10% by mass, there is a risk that crystallization may not be sufficiently promoted. The higher the calcium content, the greater the effect of promoting crystallization. From this perspective, the calcium content can also be set to 0.20% by mass or more. However, if amorphous silica is heated with a calcium content of 1.00% by mass or more, the calcium will react with the silica, easily forming substances such as Ca. 2(SiO 4) Common silica compounds. This is especially likely under high pressure. Such compounds tend to form on the periphery of silica particles, causing particle deformation and reducing particle roundness, or the silica compounds may form amorphous fine particles, thus potentially reducing flowability when mixed with resin. Therefore, the upper limit of calcium content is less than 1.00% by mass, preferably less than 0.90% by mass, and more preferably less than 0.80% by mass. Furthermore, the calcium content can be adjusted by mixing calcium or calcium compounds with amorphous silica particles as a raw material. Calcium compounds can be oxides, carbon oxides, hydroxides, nitrogen oxides, etc., and their form is not particularly limited when added. Silica, used as a raw material for amorphous silica particles, often contains calcium compounds as impurities. Therefore, raw silica or amorphous silica particles with an oxide content within an appropriate range can be prepared and adjusted to the aforementioned preferred range. Generally, calcium in silica particles with promoted crystallization can exist in the form of oxides, carbon oxides, hydroxides, nitrogen oxides, or complex oxides with silica, but it exists mostly in the form of oxides. Therefore, unless otherwise stated, in this invention, the calcium content is calculated using oxide conversion. Specifically, the calcium content is determined by ICP mass spectrometry (ICP-MS) and then converted to oxide content. (Aluminum) In one embodiment of the present invention, the spherical crystalline silica particles may contain 90-9000 ppm of aluminum (converted to metallic aluminum) based on the total mass of the spherical crystalline silica particles. If calcium is used to promote the crystallization of amorphous silica particles, it is preferable to contain 90-9000 ppm of aluminum (converted to metallic aluminum). This is not limited by a specific theory, but rather because aluminum acts as a nucleation agent during heat treatment, and when used in conjunction with calcium, it can achieve a significant effect in generating quartz crystals. However, if the aluminum content is less than 90 ppm (converted to metallic aluminum), a sufficient effect in promoting crystallization cannot be obtained. Furthermore, if the aluminum content is more than 9000 ppm (converted to metallic aluminum), it becomes easier to form a complex oxide of silica containing calcium, aluminum, and silica. Therefore, the effect of promoting crystallization by adding calcium will not only be reduced, but the increased Al content will also make it easier to form cristobalite. In other words, excess aluminum may reduce the amount of quartz crystals formed. Based on the above, the aluminum content can be set to 100 ppm or higher, or 8200 ppm or lower. Furthermore, the aluminum content can be adjusted by mixing aluminum or aluminum compounds with amorphous silica particles used as raw materials. Aluminum compounds such as alumina and aluminum hydroxide can be used. Since silica, used as raw material for amorphous silica particles, often contains aluminum compounds as impurities, raw silica or amorphous silica particles with an oxide content within an appropriate range can be prepared and adjusted to the aforementioned preferred range. The aluminum content is determined by ICP mass spectrometry (ICP-MS). Furthermore, in one embodiment of the present invention, the spherical crystalline silicon dioxide particles may also contain metallic impurities within a range that does not affect the degree of crystallinity. Typical metallic impurities include alkali metals (potassium, sodium, etc.) and alkaline earth metals (magnesium, beryllium, etc.). (Crystallic silica: 50% or more of spherical crystalline silica particles) In this invention, 50.0% or more of the total spherical crystalline silica particles are crystalline silica. Here, "total" refers to the entirety of the spherical crystalline silica particles. If the crystalline silica content is less than 50.0%, the amorphous silica ratio will be 50.0% or more. Because amorphous silica has a relatively low thermal conductivity of 1.4 W / mK, if it contains 50.0% or more of amorphous silica, the thermal conductivity of the silica particles will decrease. A higher crystalline silica ratio results in higher thermal conductivity, which is preferable. Therefore, the crystalline silica ratio can also be 60.0% or more, preferably 70.0% or more, more preferably 80.0% or more, and even more preferably 90.0% or more. There is no particular upper limit to the crystalline silicon dioxide ratio; it can be adjusted according to the application, typically based on the desired thermal conductivity. Therefore, the upper limit for the crystalline silicon dioxide ratio can be 100%, below 95%, below 90%, below 85%, or below 80%. The content of crystalline and amorphous phases can be quantitatively analyzed by X-ray diffraction. Quantitative analysis by X-ray diffraction can be performed without the use of standard samples using analytical methods such as the Rietveld method. More specifically, the ratio of crystalline silicon dioxide to the total number of spherical crystalline silicon dioxide particles (hereinafter also referred to as "crystallization rate") is calculated by determining the integrated area of ​​the amorphous peak and the crystalline peak through X-ray diffraction, and the ratio of this crystalline area is used as the crystallization rate. That is, crystallization rate is calculated as: integrated area of ​​crystalline peak / (integrated area of ​​amorphous peak + integrated area of ​​crystalline peak). (Quartz: Over 90% of crystalline silicon dioxide) In the spherical crystalline silicon dioxide particles of this invention, over 90% of the crystalline silicon dioxide is quartz. Quartz has a thermal conductivity of 12.8 W / mK, which is much greater than the thermal conductivity of amorphous silicon dioxide (1.4 W / mK). Therefore, in the spherical crystalline silicon dioxide particles of this invention, over 50.0% of the particles are crystalline silicon dioxide, and over 90% of this crystalline silicon dioxide is quartz crystal, thus achieving an ideal high thermal conductivity. Crystalline silicon dioxide may also contain crystalline phases other than quartz, such as cristobalite, tridymite, and other crystalline forms. These crystals all have a thermal conductivity of around 10 W / mK, which, although lower than quartz's 12.8 W / mK, is still higher than that of amorphous silicon dioxide. However, if the quartz content is less than 90.0%, in other words, if the content of cristobalite or tridymite is 10.0% or more, a phase transfer occurs from α-cristobalite to β-cristobalite, or from α-tridymite to β1-tridymite to β2-tridymite. Since this phase transfer is accompanied by volume expansion, when used in combination with resin, voids may sometimes form between the resin and silica particles, leading to cracks or fissures. Therefore, it is important to ensure that at least 90% of the crystalline silica is quartz and to reduce the content of cristobalite or tridymite. From this perspective, the lower the content of cristobalite or tridymite, the better. Therefore, in one embodiment of the present invention, the content of cristobalite and / or tridymite can be less than 5.0% of the total spherical crystalline silica particles. Similar to the content of crystalline and amorphous phases, the content of quartz, cristobalite, tridymite, and other crystals can be quantitatively analyzed using X-ray diffraction. Quantitative analysis of X-ray diffraction can be performed without the need for standard samples using analytical methods such as the Ritter-Wade method. More specifically, the ratio of each crystal to crystalline silica is determined by calculating the integrated area of ​​each crystal peak through X-ray diffraction and then using the ratio of these crystal areas. For example, the ratio of quartz crystals is calculated as: integrated area of ​​quartz peak / (integrated area of ​​quartz peak + integrated area of ​​cristobalite peak + integrated area of ​​tridymite peak + integrated area of ​​other crystal types). (Manufacturing Method) The spherical crystalline silica particles of the present invention can be manufactured using a method comprising the following steps. Specifically, the manufacturing method of the present invention is a method for manufacturing spherical crystalline silica particles, comprising: a raw material powder adjustment step: mixing calcium raw material, or mixing calcium raw material with lithium compound particles, into spherical amorphous silica particles to obtain a raw material powder; and a heat treatment step: subjecting the raw material powder obtained in the aforementioned raw material powder adjustment step to a heat treatment at a temperature of 1125°C or higher and 1300°C or lower, and a pressure of 125 MPa or higher, using a hot isostatic pressing apparatus for at least 1 hour to generate spherical crystalline silica particles; Regarding the spherical crystalline silica particles generated in the aforementioned heat treatment step, adjusting the mixing ratio of calcium raw material, or calcium raw material with lithium compound particles, in the aforementioned raw material powder adjustment step to a ratio of 0.10 to 1.00% by mass (calculated as oxides) and 0.05% by mass or less (calculated as oxides), to ensure that calcium is at least 0.10 to 1.00% by mass and lithium is at least 0.05% by mass (calculated as oxides). (Spherical amorphous silica particles) Spherical amorphous silica particles, used as raw materials, can be produced by methods such as melt spraying. For example, in melt spraying, silica powder that has been crushed and prepared to the desired particle size is passed through a flame, and the particles melt, and the particle shape is formed into spheres due to surface tension. To prevent the spherical particles formed by melt spraying from fusing together, the sprayed particles can be rapidly cooled. During this process, due to the rapid cooling from the molten state, the spherical silica particles do not have a crystalline structure but rather an amorphous (non-crystalline) structure. Since the spherical silica particles have undergone melt spraying, they are non-porous. These non-porous spherical silica particles are quite dense, thus an increase in thermal conductivity is expected. Through processes such as lamination, spherical amorphous silica particles can achieve an average sphericity of 0.80 or higher. The maximum temperature for subsequent heat treatment for crystallization is around 1300°C, so the sphericity of the spherical silica particles remains almost unchanged. Sphericity can vary due to agglomeration during the formation of crystalline silica particles from amorphous silica particles, but by breaking them down, crystalline silica particles with almost the same sphericity as the original amorphous silica particles can be obtained. In other words, if amorphous silica particles with a sphericity of 0.80 or higher are used, the crystalline silica particles obtained through heat treatment will also have a sphericity of 0.80 or higher. Breaking down the particles can be done using general mixers or grinders such as rotary ball mills, rocking mixers, and bead mills. When heat treatment causes a change in roundness, the rate of change in roundness can be confirmed through prior experiments or investigations, and the roundness of the spherical amorphous silica particles before heat treatment can be adjusted based on the confirmation results. Furthermore, spherical amorphous silica particles with high average roundness can be easily obtained through melt spraying. Therefore, according to the method of the present invention, spherical crystalline silica particles with a roundness of 0.8 or higher can be easily obtained. Naturally, if spherical amorphous silica particles with an average roundness of less than 0.80 are used, spherical crystalline silica particles with an average roundness of less than 0.80 can be obtained through the method of the present invention. The average particle size (D50) of spherical amorphous silica particles obtained through processes such as lamination can range from 1.0 to 100.0 μm, or even exceed 10.0 μm. The maximum temperature for subsequent crystallization heating and cooling steps is approximately 1300°C, so the particle size of the spherical silica particles remains almost unchanged. The average particle size D50 can vary due to agglomeration during the formation of crystalline silica particles from amorphous silica particles, but by breaking them down, crystalline silica particles with an average particle size almost identical to the original amorphous silica particles can be obtained. In other words, if amorphous silica particles with a D50 of 1.0 μm or more and less than 100 μm are used, the crystalline silica particles obtained by heat treatment will also be crystalline silica particles with a D50 range of 1.0 μm or more and less than 100 μm. During heat treatment, silica powder may slightly agglomerate, but by performing a fragmentation process, it will become powder with the same average particle size as before. Fragmentation can be carried out using common mixers or grinders such as rotary ball mills, roller mills, and bead mills. When the average particle size (D50) changes due to heat treatment, the rate of change of the average particle size (D50) can be confirmed through prior experiments or investigations, and the average particle size (D50) of the spherical amorphous silica particles before heat treatment can be adjusted based on the confirmation results. Moreover, the particle size of the spherical amorphous silica particles can be easily adjusted by melt spraying. Therefore, according to the method of the present invention, spherical crystalline silica particles with an average particle size (D50) of 1.0~100μm can be easily obtained. Furthermore, spherical crystalline silica particles with an average particle size (D50) of 10.0μm or more can be easily obtained. Naturally, if spherical amorphous silica particles with an average particle size (D50) of less than 1.0 μm are used, spherical crystalline silica particles with an average particle size (D50) of less than 1.0 μm can be obtained through the method of the present invention. Furthermore, if spherical amorphous silica particles with an average particle size (D50) of 10.0 μm or more are used, spherical crystalline silica particles with an average particle size (D50) of 10.0 μm or more can be obtained through the method of the present invention. Moreover, if spherical amorphous silica particles with an average particle size (D50) of more than 100.0 μm are used, spherical crystalline silica particles with an average particle size (D50) of more than 100.0 μm can be obtained through the method of the present invention. Furthermore, silica powder can be prepared by containing 90 to 9000 ppm of aluminum before melt spraying. This is not limited by a specific theory, but rather takes into account that aluminum can act as a nucleation agent during heat treatment. Through the melt spraying step (melting), aluminum is uniformly dispersed in the silica particles. Considering that aluminum can act as a nucleation agent during the subsequent heat treatment step, uniform dispersion in the silica particles allows for uniform crystal growth at lower temperatures and shorter times than conventional methods. Additionally, alumina, formed by the oxidation of aluminum, is expected to improve the chemical resistance (acid resistance, etc.) of silica particles. If the aluminum content is less than 90 ppm, the crystallization promotion effect or the improvement in chemical resistance may be insufficient. On the other hand, it is known that aluminum and alumina have the effect of lowering the melting point of silica; for example, the melting point of alumina silica glass is lower than that of pure silica glass. Therefore, if the aluminum content exceeds 9000 ppm, the melting point of the silicon dioxide particles decreases, and during heat treatment, the silicon dioxide particles easily fuse or sinter together. If the particle bonding is further increased, insufficient flowability, dispersibility, and filling properties may occur when using it as a filler in semiconductor sealants, or it may also promote wear on the machinery used in sealant manufacturing. Furthermore, semiconductor sealants generally require high purity, so adding aluminum above 9000 ppm may be unsuitable. Also, when mixing amorphous silicon dioxide particles with calcium and crystallizing them, the presence of aluminum can promote crystallization. The aluminum content can be determined by ICP mass spectrometry (ICP-MS). Even during the heat treatment stage used for crystallization, the aluminum content remains almost unchanged. Furthermore, the mass of the silicon dioxide particles remains almost unchanged before and after heat treatment. Therefore, by using spherical silica particles containing 90~9000ppm aluminum, crystallization promotion can be achieved. If the aluminum content changes due to heat treatment, the rate of change in aluminum content can be confirmed through preliminary experiments or investigations, and the aluminum content of the spherical amorphous silica particles before heat treatment can be adjusted based on the confirmation results. Furthermore, within a range that does not affect crystallization, the silicon dioxide powder before melting and spraying may also contain metallic impurities. Typical metallic impurities include alkali metals (potassium, sodium, etc.) and alkaline earth metals (magnesium, beryllium, etc.). (Calcium raw material) Calcium raw material can also be made from carbon oxides such as CaCO3. 3. Ca(OH)₃ or hydroxide 2. CaCO 3 or Ca(OH) 2. Compared to oxides, CaO is chemically more stable and poses less safety risk, making it relatively easier to handle. Furthermore, the use of CaCO₃... 3 or Ca(OH) At 2, the decomposition temperature is compared to CaCO₃. At 825℃, Ca(OH) 2. It decomposes into CaO at a relatively low temperature of 580℃. Therefore, it is conceivable that Ca(OH)₂ would be used. 2 will form CaO at a lower temperature, thus promoting crystallization and achieving crystallization into quartz, that is, the low-temperature crystallization effect of silicon dioxide. (Lithium compound particles) Lithium compound particles can be used as Li-carbon oxides. 2CO 3. Li 2CO 3. When mixed with water, its solubility is low, and the safety hazard is also low, making it relatively easy to handle. Also, Li 2CO 3 will melt at 710℃; therefore, it is advisable to consider reacting it with SiO at a temperature below its melting point. 2. The reaction proceeds and enters SiO₂. 2 particles. By allowing Li to enter SiO at such a low temperature. 2. The effect of promoting crystallization at low temperatures is expected. On the other hand, lithium is an alkali metal, and alkali metals can potentially reduce the reliability of electronic devices. Therefore, lithium compound particles do not need to be actively added, but rather can be optionally and incidentally mixed with spherical amorphous silica particles. Furthermore, the lithium contained in the heat-treated spherical crystalline silica particles can also originate from impurities contained in the amorphous silica particles used as raw materials. (Raw Material Powder Adjustment Step) In the raw material powder adjustment step, calcium raw material is mixed into spherical amorphous silicon dioxide particles, or calcium raw material is mixed with lithium compound particles to form raw material powder. The calcium raw material and lithium compound particles mixed with the spherical amorphous silica particles can be oxides, carbon oxides, hydroxides, nitrogen oxides, etc., and there are no particular limitations on their form when added. As long as they can be uniformly mixed with the amorphous spherical silica particles, they can be added in powder or aqueous solution form. The mixing method is not particularly limited as long as it ensures uniform dispersion and mixing of the raw materials in the mixture. Mixing can be carried out using a powder mixer. Through mixing, at least a portion of the spherical amorphous silica will come into contact with the calcium raw material and lithium compound particles, promoting the crystallization of the spherical amorphous silica in the subsequent heat treatment step, especially promoting crystallization into quartz. Here, regarding the spherical crystalline silica particles generated by the heat treatment step, the mixing ratio of calcium raw material, or calcium raw material and lithium compound particles, is adjusted so that calcium is 0.10 to 1.00% by mass (in oxide terms) and lithium is 0.05% or less by mass (in oxide terms). Furthermore, the aforementioned mass percentage is calculated as the total mass of the spherical crystalline silica particles, taken as 100% by mass. The mass ratio of the raw material powder obtained by this mixture remains approximately the same in the subsequent heat treatment stage for crystallization. However, since the total amount of mixed calcium raw material and lithium compound particles may not be present in the heat-treated spherical crystalline silica particles, the mixing ratio is adjusted considering the yield. Typically, if there is a difference in composition between the raw material powder and the spherical crystalline silica particles, the difference can be confirmed through preliminary testing or investigation, and the mixing ratio of calcium raw material, or calcium raw material and lithium compound particles, in the raw material powder before heat treatment can be adjusted based on the confirmation results. Furthermore, these adjustments also include situations where no adjustments are made based on prior confirmation results. As a specific example, the reduction in lithium and calcium under the heat treatment conditions used for crystallization has been previously tested and determined under the same conditions, and operation is carried out under those conditions. Therefore, by using this raw material powder, the lithium and calcium content in the spherical crystalline silicon dioxide particles of the present invention can be obtained. (Heat Treatment Step) The mixed raw material powder is heat-treated in a hot isostatic pressing apparatus at a temperature above 1125°C and below 1300°C, and a gas environment pressure above 125 MPa for at least 1 hour. During the heat treatment step, the calcium raw material and / or lithium compound particles contained in the raw material powder diffuse into the interior of the spherical amorphous silica particles, thus promoting the crystallization of the spherical amorphous silica particles into quartz. The heat treatment temperature should be between 1125°C and 1300°C. Below 1125°C, the crystallization of amorphous silica cannot be sufficiently promoted, resulting in the inability to obtain spherical crystalline silica particles comprising at least 50.0% crystalline silica. Conversely, above 1300°C, while sufficient crystallization of amorphous silica is achieved, the resulting crystalline silica may contain a significant amount of cristobalite in addition to quartz. In other words, it may be impossible to obtain spherical crystalline silica particles comprising at least 90.0% quartz. There is no particular limitation on the heating rate to the heat treatment temperature, but a rate that is too slow will reduce productivity, while a rate that is too fast will require excessive equipment performance. Therefore, a rate of 2°C / min to 20°C / min is acceptable. The gas environment pressure is 125 MPa or higher. Appropriate heat treatment sufficiently promotes the crystallization of amorphous silica. However, crystalline silica obtained under low gas environment pressure may contain a large amount of cristobalite in addition to quartz. That is, if the pressure is less than 125 MPa, it may be impossible to obtain spherical crystalline silica particles with more than 90.0% quartz composition. Considering that higher pressure promotes quartz formation, the gas environment pressure can also be 147 MPa or higher. The upper limit of pressure is not specifically limited; however, the capability limit depends on the equipment, typically around 200 MPa, but can also be 196 MPa. The heat treatment time should be at least one hour. If the heat treatment time is less than one hour, the crystallization of amorphous silica cannot be sufficiently promoted, and it may be impossible to obtain spherical crystalline silica particles that are at least 50.0% crystalline silica. Generally speaking, the longer the heat treatment time, the more promoted the crystallization. On the other hand, there is also the possibility of producing crystalline forms such as cristobalite in addition to quartz. Therefore, the heat treatment time can be adjusted appropriately according to the desired crystallization rate and quartzification rate. Therefore, there is no particular upper limit to the heat treatment time; however, considering factors such as productivity, it can be less than 24 hours, less than 20 hours, less than 16 hours, or less than 12 hours. In this invention, heat treatment is performed using a hot isostatic pressing (HIP) apparatus. A hot isostatic pressing apparatus is a pressurization treatment device that utilizes the synergistic effect of pressure and temperature to apply pressure. Typically, it can simultaneously apply high temperatures of hundreds to 2000°C and directional pressures of tens to 200 MPa to the object being treated. Ideally, without being limited by a specific theory, the following reasons can be considered for obtaining spherical crystalline silica particles with a high quartzification rate through heat treatment under high temperature and pressure. Even under normal pressure (non-high pressure), heat treatment of amorphous silica is known to promote crystallization. Furthermore, by mixing calcium raw materials into amorphous silica, the calcium contained in the calcium raw materials promotes crystallization, especially quartzification. However, the effect of calcium is limited to the areas in contact with the amorphous silica particles. Therefore, it is difficult to promote crystallization (quartzification) within the amorphous silica particles; on the other hand, the internal crystallization of amorphous silica particles can be promoted due to the influence of heat treatment (temperature). In other words, it is difficult to obtain spherical crystalline particles with a high quartzification rate. According to the present invention, by heat treatment under a pressure of 125 MPa or higher, calcium becomes more easily diffused into the interior of amorphous silica particles, thereby promoting crystallization (quartzization) within the amorphous silica particles. As a result, spherical crystalline silica particles with a high quartzization rate are obtained. Furthermore, generally speaking, the larger the particle size, the smaller the specific surface area, and the less promoted the thermal diffusion of calcium, making it difficult to obtain spherical crystalline silica particles with a high quartzization rate. According to the present invention, even with such large particle sizes, typically with an average particle size (D50) of 10.0 μm or higher, a high quartzization rate can be obtained. (Uses of Spherical Crystalline Silicon Dioxide Particles) According to one aspect of the present invention, a composite composition of the obtained spherical crystalline silicon dioxide particles and resin can be manufactured, as well as a resin composite formed by curing the resin composite composition. The composition of the resin composite composition will be described in more detail below. By using a slurry composition comprising spherical crystalline silicon dioxide particles and resin, resin composite compositions for semiconductor sealing materials (especially solid sealing materials), interlayer insulating films, etc., can be obtained. Furthermore, by curing these resin composite compositions, resin composite compositions for sealing materials (cured bodies), semiconductor packaging substrates, etc., can be obtained. In manufacturing the aforementioned resin composite, for example, in addition to spherical crystalline silicon dioxide particles and resin, hardeners, curing accelerators, flame retardants, silane coupling agents, etc., may be added as needed, and the composite is then formed using well-known methods such as kneading. Afterwards, it is molded into granules, films, etc., depending on the application. Furthermore, when hardening the aforementioned resin composite composition and manufacturing a resin composite, for example, the resin composite composition is heated and melted, processed into a shape required for the application, and then subjected to a higher heat than during melting to completely harden it. In this case, well-known methods such as transfer molding can be used. For example, when manufacturing semiconductor-related materials such as packaging substrates and interlayer insulating films, well-known resins are suitable for use in resin composites, with epoxy resins being particularly preferred. There are no particular limitations on the epoxy resin; for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, phenolic varnish type epoxy resin, cresol phenolic varnish type epoxy resin, naphthalene type epoxy resin, phenoxy type epoxy resin, etc., can be used. One of these types can be used alone, or two or more types with different molecular weights can be used in combination. From the viewpoint of curability and heat resistance, epoxy resins with two or more epoxy groups per molecule are preferred. Specifically, examples include biphenyl-type epoxy resins, phenolic varnish-type epoxy resins, o-cresol phenolic varnish-type epoxy resins, phenolic and aldehyde varnish resins epoxidized, glycidyl ethers of bisphenol A, bisphenol F, and bisphenol S, polyacids such as phthalic acid and dimer acids reacted with epichlorohydrin to obtain glycidyl ester epoxy resins, linear aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, alkyl-modified polyfunctional epoxy resins, β-naphthol phenolic epoxy resins, 1,6-dihydroxynaphthol epoxy resins, 2,7-dihydroxynaphthol epoxy resins, dihydroxybiphenyl epoxy resins, and epoxy resins incorporating halogens such as bromine to impart flame retardancy. Among these epoxy resins having two or more epoxy groups per molecule, bisphenol A-type epoxy resins are particularly preferred. Furthermore, in applications other than composite materials for semiconductor sealing materials, such as resins used as prepreg materials for printed circuit boards and resin composites of various engineering plastics, resins other than epoxy resins are also applicable. Specifically, in addition to epoxy resins, examples include silicone resins, phenolic resins, melamine resins, urea resins, unsaturated polyesters, fluoropolymers, polyimides, polyamide-imides, polyether-imides, etc.; polyesters such as polybutylene terephthalate and polyethylene terephthalate; polyphenylene sulfide, aromatic polyesters, polyurethane, liquid crystal polymers, polyether resins, polycarbonate, maleimide-modified resins, ABS resins, AAS (acrylonitrile-acrylic rubber-styrene) resins, and AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resins. As a curing agent for resin composites, well-known curing agents can be used to cure the aforementioned resin, such as phenolic curing agents. Phenolic curing agents include phenolic varnish resins, alkylphenolic varnish resins, and polyethylene phenolic resins, used alone or in combination of two or more. The amount of the aforementioned phenolic curing agent added is preferably between 0.1 and 1.0 in the equivalent ratio (phenolic hydroxyl equivalent / epoxyl equivalent) to the epoxy resin. This will eliminate unreacted phenolic curing agent residue and improve moisture absorption and heat resistance. From the viewpoint of heat resistance and thermal expansion rate, the addition amount of the spherical crystalline silica particles of this invention in the resin composite composition is preferably higher, generally between 70% and 95% by mass, more preferably between 80% and 95% by mass, and even more preferably between 85% and 95% by mass. This is because if the addition amount of spherical crystalline silica particles is too small, it is difficult to obtain the effects of improved strength and suppressed thermal expansion of the sealing material; conversely, if the addition amount is too large, regardless of whether the spherical crystalline silica particles have undergone surface treatment, the spherical crystalline silica particles in the composite material will easily cause segregation due to agglomeration, and the viscosity of the composite material will also become too high, thus making it difficult to use as a sealing material in practice. Furthermore, regarding silane coupling agents, any well-known coupling agents can be used, with those having epoxy functional groups being preferred. [Example] The present invention will be illustrated by the following examples and comparative examples. However, the present invention is not limited to the interpretation of the following examples. (Examples 1-4) Amorphous silica particles were produced by melt spraying. In melt spraying, a powder containing 0.80% by mass of calcium oxide (calculated as oxide) was used as the raw material, relative to the total mass of the fragmented silica particles and the mass of calcium oxide. The spherical amorphous silica particles (average particle size D50: 27.8 μm, roundness 0.92) were filled into a BN (boron nitride) container and heat-treated under isostatic pressure using a hot isostatic pressing (HIP) apparatus from Kobe Steel Corporation, with nitrogen as the pressure medium. The maintaining temperatures were set as follows: Example 1 (1150°C), Example 2 (1200°C), Example 3 (1250°C), and Example 4 (1300°C), with Example 1 maintained for 12 hours, Examples 2 and 3 maintained for 8 hours, and Example 4 maintained for 1 hour. The heating rate was set to approximately 600°C / hour. The nitrogen maintaining pressure at the maintaining temperature is set to 196 MPa. (Examples 5-17) The amorphous spherical silica powder used in Examples 1-4 was mixed with lithium carbonate powder. The lithium carbonate particles were mixed at 0.01% by mass (Examples 5-8), 0.02% by mass (Example 9), 0.03% by mass (Examples 10-13), and 0.05% by mass (Examples 14-17) relative to the total mass of the spherical amorphous silica and the mass of lithium (converted to oxides). The mixed powder was filled into a BN container and heat-treated under isotropic pressure using a HIP device with nitrogen as the pressure medium. The maintenance temperatures were set at 1125℃ (Example 14), 1150℃ (Example 15), 1200℃ (Examples 5, 6, 9, 10, 11, and 16), 1250℃ (Examples 7, 12, and 17), and 1300℃ (Examples 8 and 13). The maintenance time was set to 1 hour (Examples 5, 8, 9, 10, 13, and 17) and 8 hours (Examples 6, 7, 11, 12, 14, 15, and 16). The heating rate was set to approximately 600℃ / hour. The nitrogen maintenance pressure at the maintenance temperature was set to 196 MPa. (Example 18) The amorphous spherical silica powder used was the same as that used in Examples 1 to 4. This amorphous spherical silica powder was filled into a BN container and heat-treated under isotropic pressure using a HIP apparatus with nitrogen as the pressure medium. The holding temperature was set to 1250°C for 8 hours, and the heating rate was set to approximately 600°C / hour. The nitrogen holding pressure at the holding temperature was set to 147 MPa. (Examples 19 and 20) The amorphous spherical silica powder used in Examples 1 to 4 was mixed with lithium carbonate powder. The lithium carbonate particles were mixed at 0.01% by mass (calculated as oxides) relative to the total mass of the spherical amorphous silica and the mass of lithium (calculated as oxides). The mixed powder was filled into a BN container and heat-treated under isotropic pressure using a HIP apparatus with nitrogen as the pressure medium. The holding temperature was set to 1250°C for 8 hours, and the heating rate was set to approximately 600°C / hour. The nitrogen holding pressure at the holding temperature was set to 147 MPa (Example 19) and 125 MPa (Example 20). (Examples 21-31) Amorphous silica particles were prepared by melt spraying. Calcium hydroxide particles and lithium carbonate particles were mixed into these spherical amorphous silica particles (average particle size D50: 30.2 μm, roundness 0.91). The following concentrations of calcium hydroxide particles (calculated as oxide) and lithium carbonate particles (calculated as oxide) were mixed relative to the total mass of the spherical amorphous silica, the total mass of calcium (calcium) in oxide form, and the total mass of lithium in oxide form: 0.20% (calcium hydroxide) in oxide form, 0.01% (Examples 22-24), 0.03% (Example 25), and 0.05% (Examples 26-31). The mixed powder was filled into a BN container and heat-treated under high axial pressure using a HIP device with nitrogen as the pressure medium. The temperature was maintained at 1250°C for 8 hours (Examples 21, 23, 25, 29, and 31); at 1150°C for 12 hours (Example 22); at 1300°C for 1 hour (Examples 24 and 30); at 1125°C for 12 hours (Example 26); and at 1200°C for 8 hours (Examples 27 and 28). The heating rate was set to approximately 600°C / h. The nitrogen pressure maintained at the temperature was set to 196 MPa (Examples 21-27, 29, and 30), 147 MPa (Example 31), and 125 MPa (Example 28). (Examples 32-40) Amorphous silica particles were prepared by melt spraying. Calcium hydroxide particles and lithium carbonate particles were mixed into these spherical amorphous silica particles (average particle size D50: 2.20 μm, sphericity 0.93). The following concentrations of calcium hydroxide particles (calculated as oxide) and lithium carbonate particles (calculated as oxide) were mixed relative to the total mass of the spherical amorphous silica, calcium (calculated as oxide) at 0.90% (calculated as oxide), and lithium carbonate (calculated as oxide) at 0.01% (Example 36), 0.03% (Example 37), and 0.05% (Examples 38, 39, and 40). The mixed powder was filled into a BN container and heat-treated under high axial pressure using a HIP device with nitrogen as the pressure medium. The temperature was maintained at 1125°C for 12 hours (Example 38); 1150°C for 12 hours (Example 32); 1200°C for 8 hours (Example 33); 1250°C for 8 hours (Examples 34, 36, 37, 39, and 40); and 1300°C for 1 hour (Example 35). The heating rate was set to approximately 600°C / hour. The nitrogen pressure maintained at the temperature was set to 196 MPa (Examples 32, 34-39), 147 MPa (Example 40), and 125 MPa (Example 33). (Comparative Examples 1-9) The amorphous spherical silica powder used in Examples 1-4 was used. Powders without lithium carbonate powder mixed in the silica powder (Comparative Examples 1, 2, and 7) and powders mixed with lithium carbonate powder (Comparative Examples 3-6, 8, and 9) were prepared. Regarding the mixing of lithium carbonate, the lithium carbonate particles were mixed at a concentration of 0.01% by mass (Comparative Examples 3, 5, and 8) and 0.05% by mass (Comparative Examples 4, 6, and 9) relative to the total mass of the aforementioned spherical amorphous silica and the mass of lithium converted to oxides. The powders without lithium carbonate powder and the mixed powders were filled into a BN container and heat-treated under isotropic pressure using a HIP apparatus with nitrogen as the pressure medium. The maintenance temperature was set to 1100℃ (Comparative Examples 1, 3, 4, and 7) and 1350℃ (Comparative Examples 2, 5, 6, 8, and 9). The maintenance time was set to 12 hours (Comparative Examples 1, 3, 4, and 7) and 1 hour (Comparative Examples 2, 5, 6, 8, and 9). The heating rate was set to approximately 600℃ / hour. The nitrogen maintenance pressure at the maintenance temperature was set to 196 MPa (Comparative Examples 1-6) and 147 MPa (Comparative Examples 7-9). (Comparative Examples 10-13) Amorphous spherical silica powder used in Examples 1-4 was used. A powder without lithium carbonate powder mixed in the silica powder (Comparative Example 10) and a powder mixed with lithium carbonate powder were prepared (Comparative Examples 11-13). Regarding the mixing of lithium carbonate, the lithium carbonate particles were mixed at 0.01% by mass (Comparative Example 11), 0.03% by mass (Comparative Example 12), and 0.05% by mass (Comparative Example 13) relative to the total mass of the aforementioned spherical amorphous silica and the mass of lithium converted to oxides. The powder without lithium carbonate powder and the mixed powder were filled into a BN container, and heat-treated under high axial pressure using a HIP apparatus with nitrogen as the pressure medium. The holding temperature was set to 1250°C. The holding time was set to 8 hours (Comparative Examples 10-12) and 1 hour (Comparative Example 13). The heating rate was set to approximately 600°C / hour. The nitrogen pressure maintained at the maintenance temperature was set to 118 MPa (Comparative Examples 10 to 13). (Comparative Examples 14 and 15) The amorphous spherical silica powder used in Examples 1 to 4 was used. A powder without lithium carbonate powder was prepared (Comparative Example 14), and a powder with lithium carbonate powder was prepared (Comparative Example 15). Regarding the mixing of lithium carbonate, the lithium carbonate particles were mixed at 0.05% by mass (calculated as oxides) relative to the total mass of the aforementioned spherical amorphous silica and the mass of lithium in oxide form. The powder without lithium carbonate powder and the mixed powder were filled into an alumina container and heat-treated using a SUPER-BURN electric furnace (manufactured by MOTOYAMA Co., Ltd.) in an atmospheric atmosphere (atmospheric pressure). The temperature was increased to 1250°C at a rate of approximately 600°C / hour and held for 8 hours (Comparative Example 14) and 1 hour (Comparative Example 15). Afterward, the temperature was cooled to room temperature at a rate of approximately 100°C / hour. (Comparative Examples 16-18) The amorphous spherical silica powder used in Examples 21-31 was used. The powder was adjusted to contain only calcium hydroxide particles mixed within the spherical amorphous silica particles (average particle size d50: 30.2 μm). The calcium was mixed at 0.20% by mass (calculated as oxides) relative to the total mass of the spherical amorphous silica and the mass of calcium (converted as oxides). The mixed powder was filled into a BN container and heat-treated under isotropic pressure using a HIP apparatus with nitrogen as the pressure medium. The holding temperatures were set to 1100°C (Comparative Example 16), 1350°C (Comparative Example 17), and 1250°C (Comparative Example 18). The holding times were set to 12 hours (Comparative Example 16), 1 hour (Comparative Example 17), and 8 hours (Comparative Example 18). The heating rate was set to approximately 600°C / hour. The nitrogen maintaining pressure at the maintaining temperature was set to 196 MPa (Comparative Example 16, Comparative Example 17) and 118 MPa (Comparative Example 18). (Comparative Examples 19-22) The amorphous spherical silica powder used in Examples 21-31 was used. A powder was prepared by mixing both calcium hydroxide particles and lithium carbonate particles (Comparative Examples 19-22) into the spherical amorphous silica particles (average particle size d50: 30.2 μm). For a powder in which only calcium hydroxide particles were mixed with amorphous silica particles, a specific amount of calcium was mixed, relative to the total mass of the spherical amorphous silica and the mass of calcium converted to oxides. On the other hand, regarding the powder composed of spherical amorphous silica particles mixed with calcium hydroxide particles and lithium carbonate particles, relative to the total mass of the spherical amorphous silica, the calcium hydroxide particles were mixed to a calcium oxide content of 0.20% by mass, and the lithium carbonate particles were mixed to a lithium oxide content of 0.01% by mass (Comparative Example 19, Comparative Example 21) and 0.05% by mass (Examples 20, Examples 22). The aforementioned mixed powder was filled into a BN container and heat-treated under isotropic pressure using a HIP device with nitrogen as the pressure medium. The holding temperature was set to 1100°C (Comparative Example 19, Comparative Example 20) and 1350°C (Comparative Example 21, Comparative Example 22), and the holding time was set to 12 hours (Comparative Example 19, Comparative Example 20) and 1 hour (Comparative Example 21, Comparative Example 22). The heating rate was set to approximately 600°C / hour. The nitrogen maintaining pressure at the maintaining temperature is set to 196 MPa. (Comparative Examples 23-25) Amorphous spherical silica particles used in Examples 32-40 were used. The powder was adjusted to consist only of calcium hydroxide particles mixed with the spherical amorphous silica particles (average particle size d50: 2.2 μm). The calcium was mixed at 0.90% by mass (calculated as oxides) relative to the total mass of the spherical amorphous silica and the mass of calcium (calculated as oxides). The mixed powder was filled into a BN container and heat-treated under isotropic pressure using a HIP apparatus with nitrogen as the pressure medium. The holding temperatures were set to 1100°C (Comparative Example 23), 1350°C (Comparative Example 24), and 1250°C (Comparative Example 25), and the holding times were set to 12 hours (Comparative Example 23), 1 hour (Comparative Example 24), and 8 hours (Comparative Example 25). The heating rate was set to approximately 600°C / hour. The nitrogen maintaining pressure at the maintaining temperature was set to 196 MPa (Comparative Example 23, Comparative Example 24) and 118 MPa (Comparative Example 25). (Comparative Examples 26-29) Amorphous spherical silica particles used in Examples 32-40 were used. A powder was prepared by mixing calcium hydroxide particles and lithium carbonate particles into the spherical amorphous silica particles (average particle size d50: 2.2 μm). The calcium hydroxide particles were mixed to a concentration of 0.90% by mass (calcium in oxide form) and the lithium carbonate particles were mixed to a concentration of 0.01% by mass (Comparative Examples 26 and 28) and 0.05% by mass (Examples 27 and 29) (calcium in oxide form) relative to the total mass of the spherical amorphous silica particles. The mixed powder was filled into a BN container and heat-treated under isotropic pressure using a HIP apparatus with nitrogen as the pressure medium. The maintenance temperature was set to 1100℃ (Comparative Examples 26 and 27) and 1350℃ (Comparative Examples 28 and 29), and the maintenance time was set to 12 hours (Comparative Examples 26 and 27) and 1 hour (Comparative Examples 28 and 29). The heating rate was set to approximately 600℃ / hour. The nitrogen maintenance pressure at the maintenance temperature was set to 196 MPa. The silicon dioxide particles obtained in the examples and comparative examples are shown in Tables 1 and 2, respectively. The determination methods for each item in Tables 1 and 2 are explained. (Composite Ratio) The ratio of amorphous to crystalline silica particles obtained by heat treatment, as well as the types and ratios of crystalline silica, are obtained by XRD. In this invention, the X-ray diffraction device "D2 PHASER" (manufactured by Bruker) is used. Quantitative analysis of the crystalline phase using the Ritvel method is performed using the crystal structure analysis software "TOPAS" (manufactured by Bruker). If the spherical crystalline silica particles are composed of amorphous and crystalline silica, the ratio of amorphous to crystalline silica, as well as the types and ratios of crystalline silica, can be calculated by the sum of the integrated intensities (Ic) of the crystalline peaks measured by XRD and the integrated intensity (Ia) of the halo portion of the amorphous peaks, using the following formula to obtain the ratio of the crystalline phases. More specifically, the ratio of crystalline silica phases contained in spherical crystalline silica particles can be determined. X (crystallinity ratio) = Ic / (Ic+Ia)×100 (%) In this invention, XRD measurements are performed in the range of 2Θ = 10° to 90°. The crystallinity ratio is determined by the sum of the intensities of the crystalline peaks appearing within this 2Θ measurement range and the integrated intensity of the broad halo peaks near 2Θ = 22° that originate from amorphous materials. Furthermore, the quantitative analysis of the crystalline phase using the Ritter-Wade method is performed without the use of standard samples. (Roundness) Roundness is determined using flow cytometry particle image analysis. This invention utilizes the "FPIA-3000" flow cytometry particle image analysis device (manufactured by Spectris). The average particle size (D50) of spherical quartz particles was determined by laser diffraction and scattering particle size distribution measurement method. The present invention uses the laser diffraction and scattering particle size distribution measurement device "CILAS920" (manufactured by CIRRUS). (Impurity or Additive Content) In this invention, the content of impurities or additive elements such as lithium and calcium in the spherical silicon dioxide particles is determined by ICP-MS. Specifically, it is determined using an ICP-MS (Agilent "7700X") according to JIS-K0133. An aqueous solution prepared by completely dissolving the silicon dioxide particles in hydrofluoric acid is used as the sample. Here, the content of impurity elements contained in the silicon dioxide particles is considered as the content of impurity elements in the silicon dioxide solution. The calibration curve is a standard solution containing only reagents. (Regarding impurities in amorphous spherical silica particles) In the examples and comparative examples, the zinc content in the spherical amorphous silica particles produced by the sputtering method was less than 1.0 ppm (converted to metal content), and the total alkali metals (Li, K, and Na) were 22-38 ppm (converted to metal content). In the amorphous spherical silica particles described in Examples 1-18 and Comparative Examples 1-15, where calcium was added during sputtering, the calcium content was 7931 ppm; while in the amorphous spherical silica particles used in Examples 19-28 and Comparative Examples 16-27, the total alkaline earth metals (Ca+Mg+Ba) were 11-32 ppm, and the aluminum metal content was 97-8230 ppm. [Table 1] [Table 2] (Regarding Examples and Comparative Examples) According to the embodiments of the present invention, each example yields spherical crystalline silica particles with a lithium content of 0.05% by mass or less (converted from oxides), a calcium content of 0.10% by mass or more but less than 1.0% by mass (converted from oxides), and a total content of 50.0% or more being crystalline silica, of which 90.0% or more is quartz. The particles according to the embodiments of the present invention have a sphericity of 0.86 to 0.92. Regarding the average particle size, the embodiments of the present invention use three types of amorphous spherical silica with average particle sizes of 27.8 μm, 30.2 μm, and 2.20 μm as raw materials. The silica particles of the present invention using a raw material with an average particle size of 27.8 μm have an average particle size of 27.8 μm to 30.2 μm. Furthermore, the silicon dioxide of the present invention, which uses raw materials with an average particle size of 30.2 μm, has an average particle size of 32.3 μm to 33.8 μm. Additionally, the silicon dioxide particles of the present invention, which use raw materials with an average particle size of 2.2 μm, have an average particle size of 2.3 μm to 2.6 μm. (Regarding heat treatment temperature) Compared with Comparative Examples 1 to 9, Examples 1 to 20 show that by using raw materials with a lithium content of less than 0.05% by mass (calculated as oxide) and a calcium content of more than 0.10% by mass and less than 1.0% by mass (calculated as oxide), and by heat treatment at a temperature of 1125°C to 1300°C under an isotropic pressure of 125 to 196 MPa in a gas environment, it is possible to achieve a total content of more than 50.0% crystalline silicon dioxide and more than 90.0% of the aforementioned crystalline silicon dioxide being quartz. (Regarding the types of amorphous spherical silicon dioxide used as raw materials) (Using amorphous spherical silicon dioxide with an average particle size of 30.2 μm as raw material) Compared with Comparative Examples 16, 17, 19 to 22, Examples 21 to 31 and Examples 32 to 40 (using amorphous spherical silicon dioxide with an average particle size of 2.20 μm as raw material) compared with Comparative Examples 23, 24, 26 to 29, it can be seen that even when using raw materials with a lithium content of less than 0.05% by mass (converted from oxides) and a calcium content of more than 0.10% by mass and less than 1.0% by mass (converted from oxides), and with different average particle sizes, it is still possible to achieve a total content of more than 50.0% crystalline silicon dioxide and more than 90.0% of the aforementioned crystalline silicon dioxide being quartz, under a gas pressure of more than 125 MPa in the same direction and a heat treatment temperature of 1125°C to 1300°C. (Regarding the isotropic pressure of the gas environment) Comparing Examples 3, 7, 12, 17-20 with Comparative Examples 10-15, it is evident that even with the same heat treatment holding temperature of 1250°C, an isotropic pressure of the gas environment of at least 125 MPa is required to achieve a total composition of at least 50.0% crystalline silicon dioxide, and at least 90.0% of the aforementioned crystalline silicon dioxide being quartz. It is conceivable that if the isotropic pressure of the gas environment is less than 125 MPa, the appearance of cristobalite will increase, resulting in a quartz content in the crystalline silicon dioxide falling below 90%. Therefore, an isotropic pressure of at least 125 MPa and a heat treatment temperature between 125°C and 1300°C are essential. Furthermore, compared to Comparative Example 18, Examples 21 to 31 (using amorphous spherical silica with an average particle size of 30.2 μm as raw material) and Examples 32 to 40 (using amorphous spherical silica with an average particle size of 2.20 μm as raw material) also use raw materials with different average particle sizes. It is evident that even when using raw materials with lithium content (calculated as oxide) of less than 0.05% by mass and calcium content (calculated as oxide) of 0.10% by mass or more but less than 1.0% by mass, if the isotropic pressure of the gas environment is less than 125 MPa, the formation of scabbsite will increase, resulting in a quartz content in the crystalline silica falling below 90%. Therefore, it is conceivable that an isotropic pressure of 125 MPa or more and a heat treatment temperature of 1125°C to 1300°C or less are necessary. (none)

Claims

1. A spherical crystalline silicon dioxide particle having a sphericity of 0.80 or higher, an average particle size (D50) of 1.0 μm or higher and 100.0 μm or lower, wherein the average particle size is the median particle size, containing less than 0.02% by mass of lithium (converted from oxides), containing 0.10 to less than 1.00% by mass of calcium (converted from oxides), wherein the particle is 50.0% or more of crystalline silicon dioxide, and wherein more than 90.0% of the crystalline silicon dioxide is quartz.

2. The spherical crystalline silica particles as claimed in claim 1, wherein scabolith comprises less than 5.0% of the total.

3. The spherical crystalline silicon dioxide particles as claimed in claim 1 or 2, containing 90 to 9000 ppm of aluminum.

4. The spherical crystalline silicon dioxide particles of claim 1 or 2 have an average particle size (D50) of 10.0 μm or more.

5. A method for manufacturing spherical crystalline silica particles, comprising: a raw material powder adjustment step: mixing calcium raw material, or mixing calcium raw material and lithium compound particles, into spherical amorphous silica particles to obtain a raw material powder; and a heat treatment step: subjecting the raw material powder obtained in the aforementioned raw material powder adjustment step to a temperature of 1125°C or higher and 1300°C or lower, and a pressure of 125 MPa or higher, using a hot isostatic pressing apparatus for at least 1 hour to generate spherical crystalline silica particles; wherein the spherical crystalline silica particles generated in the aforementioned heat treatment step are adjusted such that calcium is 0.10 to 1.00% by mass (converted from oxides) and lithium is less than 0.02% by mass (converted from oxides), by adjusting the mixing ratio of calcium raw material, or calcium raw material and lithium compound particles, in the aforementioned raw material powder adjustment step.

6. A resin composite composition, characterized in that the resin contains spherical crystalline silicon dioxide particles as claimed in any one of claims 1 to 4.

7. A resin composite, characterized in that it is formed by curing a resin composite composition as claimed in claim 6.