JP2018030759A - Irregularly shaped silica powder, method for producing the same, and resin composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide irregularly shaped silica powder which does not lower a filling ratio when formed into a filler for sealing material, does not cause damaging on a semiconductor element surface and a wire and die wear, and is excellent in bending strength, adhesive strength and solder reflow resistance in a resin after molding.SOLUTION: In irregularly shaped silica powder, a median diameter of a weight standard particle size distribution is in a specific range, the maximum of the weight standard particle size distribution is one, a geometric standard deviation σg is a specific value or less, and a degree of unevenness is in a specific range.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a deformed silica powder, a production method thereof, and a resin composition containing the same.

In recent years, miniaturization, thinning, and high-density mounting of semiconductor devices are rapidly progressing, and the narrowing of semiconductor mounting is progressing. Along with the narrowing of the gap, generally, a spherical silica having a BET specific surface area of ^{2 to} 30 m ² / g and a particle diameter of 0.1 to 1.5 μm in terms of primary particle size as a filler for a high-density semiconductor mounting sealant. Powder is used.

  When spherical silica is used as the filler, it is known that the stress in the resin after molding is low due to the smoothness of the surface. It is natural to add silica at a high filling rate in order to improve the thermal conductivity and dimensional stability of the encapsulant, but it improves the bending strength, adhesive strength, and solder reflow resistance against the above stress reduction. From this point of view, it was a problem to increase the packing of silica.

  However, silica powder having a BET specific surface area in the above range has a problem that it is difficult to suppress an increase in viscosity of the resin composition when the resin is highly filled, and the fluidity of the resin composition is lowered. That is, when a resin composition having low fluidity is used for a narrow gap semiconductor mounting application, defective molding occurs, and there is a limit to the high filling of silica.

  By the way, it is known that blending crushed silica with spherical silica in a certain ratio as a filler is effective in improving fracture toughness, bending strength, solder reflow resistance, and the like. However, when crushing silica is mixed, in addition to problems such as a decrease in filling rate and fluidity, the shape of the crushing surface of crushing silica is angular, so it is easy to damage the semiconductor element surface and wires, There was a problem of causing mold wear. Document 1 describes a resin composition in which the above problem is improved by filling a crushed silica powder having a specified roundness.

JP 2001-146413 A

  However, in the sealing material for high-density semiconductor mounting where high packing of silica is an issue, the present inventors have a crushing surface with a specified roundness, and there is room for further improvement. Found.

  The present invention has been made in view of the above problems, and its purpose is to maintain the filling rate of the resin and to provide a resin composition with excellent bending strength, adhesive strength, and solder reflow resistance. It is to provide silica for filling material.

  In order to solve the above problems, the present inventors have not only maintained a high filling rate and high fluidity, but also a resin composition when silica powder having specific physical properties is used as a filler for a sealing material. It has been found that there is an effect on the bending strength, adhesive strength, and solder reflow resistance of an object, and the present invention has been completed. That is, the present invention has the following configuration.

[1] The median diameter of the weight-based particle size distribution measured by the centrifugal sedimentation method is in the range of 50 to 1000 nm, and the area (S) obtained by the image analysis method and the envelope area (S ₀ obtained by the image analysis method) )) (S / S ₀ ) in the range of 0.60 to 0.95, there is one maximum (peak) of the weight-based particle size distribution obtained by the centrifugal sedimentation method, and the geometric standard deviation σg Is a deformed silica powder characterized by having a saturated moisture content of 1.5% by mass or less measured by a loss on drying method at 120 ° C.

  [2] The deformed silica powder according to [1], wherein the average circularity of particles obtained by an image analysis method is in the range of 0.40 to 0.85.

  [3] The deformed silica powder according to [1] or [2], wherein the content of particles having a circularity of 0.95 or more obtained by an image analysis method is 5% by number or less.

  [4] The deformed silica powder according to any one of [1] to [3], wherein the contents of sodium, potassium and iron are each less than 1 ppm.

  [5] The deformed silica powder according to any one of [1] to [4], which has hydrophobicity.

  [6] A resin composition containing the deformed silica powder according to any one of [1] to [5].

  [7] An alkoxysilane or a hydrolyzate thereof and / or a partial condensate thereof is added to the fumed silica dispersion and subjected to a polycondensation reaction to obtain a reaction solution in which the deformed silica particles are suspended, and from the obtained reaction solution A method for producing deformed silica powder, comprising: a step of recovering deformed silica particles; a step of firing the recovered deformed silica particles; and a step of pulverizing the deformed silica particles obtained from the firing step.

  [8] The method for producing deformed silica powder according to [7], further comprising a step of hydrophobizing the surface of the obtained deformed silica particles.

  [9] A core-shell type deformed silica powder composed of a core part and a shell part covering the core part, wherein the core part is made of fumed silica, and the shell part is obtained by a sol-gel method. A deformed silica powder having a saturated water content of 1.5% by mass or less measured by a loss on drying method at 120 ° C.

  [10] The deformed silica powder according to claim 9, wherein the surface of the shell portion is surface-treated.

  According to the present invention, when it is used as a filler for a semiconductor encapsulant, it does not cause damage to the surface of the semiconductor element or wire or wear of the mold, and in the resin after molding, bending strength, adhesive strength, and solder resistance Since it is excellent in reflow property, it is suitably used for various electric and electronic parts.

It is a figure which shows the irregular shaped silica powder which concerns on one Embodiment of this invention. It is a figure which shows an example of the graph showing a weight reference | standard particle size distribution. It is a schematic diagram showing how to obtain the envelope area obtained by obtained area (S) and the image analysis obtained by the image analysis method (S _0). It is the schematic which compared the manufacturing method of the irregular shaped silica powder which concerns on one Embodiment of this invention, and the manufacturing method of the conventional spherical silica powder. It is the schematic which compared the manufacturing method of the deformed silica powder which concerns on one Embodiment of this invention, and the manufacturing method of the conventional deformed silica powder. FIG. 1 is a diagram for explaining a method for measuring the adhesive strength after resin curing in a resin composition obtained by adding metal oxide particles to an acrylic resin, implemented in each example of the present application.

  Embodiments of the present invention will be described in detail below. For convenience of explanation, members having the same function are denoted by the same reference numerals and description thereof is omitted. Unless otherwise specified in this specification, “A to B” representing a numerical range means “A or more (including A and greater than A) and B or less (including B and less than B)”.

[1. (Deformed silica powder)
First, the outline of the deformed silica powder will be described below. In the present specification, “silica powder” intends an aggregate of silica particles having a particle size distribution, and includes “silica particles”. In this specification, the expression “silica powder” is used to describe the state after drying and the particle size distribution, and the expression “silica particles” is used to describe the state or number dispersed in the liquid. There is also.

  FIG. 1 is a diagram showing deformed silica powder according to an embodiment of the present invention. FIG. 1 shows an image acquired by a scanning electron microscope (SEM). As will be described later, the irregular-shaped silica powder is obtained by using beaded particles as a core and growing the particles. In other words, it can be said that the deformed silica powder is obtained by growing secondary particles, in which spherical primary particles are fused, as nuclei. Therefore, the irregular-shaped silica powder is an irregular-shaped silica powder as shown in FIG. 1 and is substantially free of spherical silica particles, and further has substantially no angular shape such as a crushed surface. It is.

  In the present specification, the “irregular shape” means not spherical (non-spherical). Since this deformed silica powder has the structure described in the embodiments described later, it can maintain a high filling rate when used as a filler for a semiconductor encapsulant, so that it has thermal conductivity, dimensional stability, and solder resistance. It excels in reflowability and excels in bending strength and adhesive strength without causing damage to the surface of the semiconductor element or wire or wear of the mold.

  Hereinafter, each configuration of the deformed silica powder will be described in detail.

[Embodiment 1]
This deformed silica powder has a median diameter of the weight-based particle size distribution measured by the centrifugal sedimentation method in the range of 50 to 1000 nm. The area (S) obtained by the image analysis method and the envelope area obtained by the image analysis method _{(S 0)} and the ratio of (S / _{S 0)} is in the range of from 0.60 to 0.95, is one local maximum (peak) of the weight particle size distribution obtained by centrifugal sedimentation, and geometric The standard deviation σg is 1.5 or less, and the saturated water content measured by the loss on drying method at 120 ° C. is 1.5% by mass or less. The S / S ₀ represents the degree of irregularities of the irregular silica powder surface. The physical properties of the irregular shaped silica powder will be described in detail below.

<1-1. Median diameter of weight-based particle size distribution>
This deformed silica powder has a median diameter of the weight-based particle size distribution measured by centrifugal sedimentation in the range of 50 to 1000 nm. The median diameter is preferably 120 nm or more, more preferably 250 nm or more, and further preferably 300 nm or more. The median diameter is preferably 500 nm or less.
If it is in said numerical range, it can be conveniently used as a filler of a semiconductor sealing material.

  In this specification, the median diameter of the weight-based particle size distribution by the centrifugal sedimentation method is the dispersion particle obtained by dispersing irregularly shaped silica powder in a dispersion medium under the conditions of an output of 20% at a concentration of 1.5% by mass and a dispersion time of 45 minutes. Means the median diameter of the weight-based particle size distribution. As the dispersion medium, water is used in the case of hydrophilic deformed silica, and 2-propanol is used in the case of hydrophobic deformed silica.

  As an example of the particle size distribution measuring machine used in the centrifugal sedimentation method, there is CPS disk centrifugal sedimentation type particle size distribution measuring apparatus DC-24000.

<1-2. Unevenness>
The deformed silica powder has a ratio (S / S ₀ ) between the area (S) obtained by the image analysis method and the envelope area (S ₀ ) obtained by the image analysis method of 0.60 to 0.95. Is in range. In this specification, the ratio (S / S ₀ ) between the area (S) obtained by the image analysis method and the envelope area (S ₀ ) obtained by the image analysis method is also referred to as the degree of unevenness. The closer the degree of unevenness is to 1, the smaller the degree of unevenness (that is, closer to the state without unevenness).

  If the degree of unevenness is 0.95 or less, the deformed silica powder has sufficient unevenness, so that the bending strength and the adhesive strength are improved in the molded resin when used as a semiconductor sealing material. . The degree of irregularity contributes to mechanical strength and adhesive strength because the smaller the value, the greater the irregularity of the particles. Usually, it is 0.60 or more.

  The degree of unevenness is preferably 0.93 or less, more preferably 0.90 or less, and even more preferably less than 0.90. Further, the degree of unevenness is preferably 0.60 or more, and more preferably 0.70 or more.

  Further, in the irregular shaped silica powder, the content of particles having an unevenness degree of 0.97 or more is preferably 10% by number or less, more preferably 7% by number or less, and 6% by number or less. More preferably. The content of particles having an unevenness degree of 0.97 or more is preferably 10% by number or less because the content of particles having no unevenness is extremely small.

In this specification, the degree of unevenness obtained by the image analysis method is determined by taking an image of 500 or more silica particles, analyzing the image, and analyzing the area (S) of each particle and the convexity of each particle. The envelope area (S ₀ ) surrounded by the envelope line connecting the parts is obtained, and the ratio (S / S ₀ ) between the area of each particle and the envelope area is calculated and averaged.

Specifically, the area (S) and the envelope area (S ₀ ) were measured using a FE-SEM to take a bright field-scanning transmission image (BF-STEM) of silica particles, and the photographed image was analyzed using image analysis software. It can be obtained by incorporating into “A Image-kun” (Asahi Kasei Engineering Co., Ltd.) and conducting particle analysis.

FIG. 3 is a schematic diagram illustrating a method for obtaining the area (S) obtained by the image analysis method and the envelope area (S ₀ ) obtained by the image analysis method. In FIG. 3, the area of the particle 16 obtained by the image analysis method is S, and the area surrounded by the envelope 17 connecting the convex portions of the particle 16 is S ₀ .

  In the present specification, the content of particles having an unevenness degree of 0.97 or more obtained by an image analysis method means the number ratio of particles having an unevenness degree of 0.97 or more.

<1-3. Maximum (peak) of particle size distribution and geometric standard deviation σg>
This deformed silica powder has one maximum (peak) of the weight-based particle size distribution obtained by centrifugal sedimentation, and has a geometric standard deviation σg of 1.50 or less. The geometric standard deviation σg represents the width of the particle size distribution. As the value of the geometric standard deviation σg is closer to 1, it means that the width of the particle size distribution is narrower and the maximum is sharper.

  FIG. 2 is a diagram illustrating an example of a graph representing a weight-based particle size distribution. As illustrated in FIG. 2, the irregular shaped silica powder has one maximum (peak) of weight-based particle size distribution. On the other hand, conventional deformed silica powders are generally obtained by agglomerating spherical fine silica particles and then growing the grains, so that large-sized spherical silica particles derived from unaggregated silica particles are obtained. A certain amount will be included. That is, since it contains spherical silica particles and non-spherical silica particles, the particle size distribution becomes broad. For this reason, the weight-based particle size distribution of the conventional silica powder is wider than that of FIG. 2 (that is, the geometric standard deviation σg is increased) and / or the weight-based particle size distribution has a plurality of local maximums (peaks). Therefore, by using this weight-based particle size distribution as an index, it can be seen that the deformed silica powder is different from the conventional deformed silica powder.

  The geometric standard deviation σg is more preferably 1.45 or less, further preferably 1.42 or less, further preferably 1.40 or less, and particularly preferably 1.38 or less. preferable. If it is within such a range, it does not contain coarse particles that cause molding defects in narrowing gaps or fine particles that cause viscosity increases, so it is suitable for use as a sealant for high-density semiconductor packaging sealants. it can.

  In this specification, the maximum of the weight-based particle size distribution by the centrifugal sedimentation method is the same as the median diameter of the above-mentioned weight-based particle size distribution. Means the maximum of the weight-based particle size distribution of the dispersed particles obtained by dispersing in a dispersion medium. As the dispersion medium, water is used in the case of hydrophilic deformed silica, and 2-propanol is used in the case of hydrophobic deformed silica. In the present specification, the geometric standard deviation σg of the particle size distribution is obtained by performing logarithmic average distribution fitting (the least square method) on the weight-based particle size distribution obtained as described above in the range of the cumulative frequency of 10% by mass to 90% by mass. Means the value calculated from the fitting.

<1-4. Saturated water content>
The deformed silica powder has a saturated moisture content of 1.5% by mass or less as measured by a loss on drying method at 120 ° C. The smaller the saturated water content, the better the long-term storage stability in the resin composition when used as a filler for a sealing material. When a resin composition filled with silica having a large amount of saturated moisture is stored for a long period of time, cracks in the resin after molding or the substrate may occur and the yield may decrease.

  Therefore, the lower the saturated water content, the better. The amount of saturated water is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, but usually 0.1% by mass or more.

  In this specification, the value obtained by the saturated water content method is meant. 10 g of silica particles were dried at 120 ° C. for 24 hours, and then cooled in a desiccator containing silica gel. Subsequently, the particles cooled in the desiccator were allowed to stand for 48 hours in an environment of 25 ° C. and 50% RH, and the mass (Dwet) of the particles was weighed. The weighed particles were dried again at 120 ° C. for 24 hours, and the mass (Ddry) of the particles was weighed. The value calculated by the following mathematical formula (2) from the change in mass before and after humidity control was taken as the saturated moisture content.

Saturated water content = ((Dwet−Ddry) / Ddry (2)
<1-5. Circularity and average circularity>
The deformed silica powder preferably has an average circularity of particles obtained by an image analysis method in the range of 0.40 to 0.85. In this specification, “circularity” is calculated for each particle, and “average circularity” is intended to mean a value obtained by calculating the average circularity of a powder (aggregate of particles). The closer the circularity is to 1, the closer it is to a sphere. That is, the degree of circularity (that is, the degree of non-spherical shape) of the irregular-shaped silica powder is known from the circularity.

  Moreover, it shows that the ratio of the particle | grains close | similar to the spherical shape contained in powder is so large that an average circularity is near 1.

  The average circularity is more preferably 0.80 or less, and further preferably 0.75 or less. The average circularity is more preferably 0.50 or more, and further preferably 0.55 or more.

  In this deformed silica powder, the content of particles having a circularity of 0.95 or more obtained by an image analysis method is preferably 5% by number or less, more preferably 3% by number or less, and more preferably 1% by number. More preferably, it is as follows. If the content of the particles having a circularity of 0.95 or more is 5% by number or less, the content of particles close to a spherical shape is small, which is preferable.

  In this specification, the average circularity of the particles obtained by the image analysis method is such that images of 500 or more silica particles are taken and analyzed, and the area (S) of each particle and each silica are analyzed. The peripheral length of the particles is obtained, and the circularity of each particle is calculated from the following formula (1) and averaged.

Circularity = 4π × area / (peripheral length) ² (1)
Specifically, as with the degree of unevenness, the circularity is obtained by taking a bright field-scanning transmission image (BF-STEM) using FE-SEM for each silica particle, and using the photographed image analysis software. It can be obtained as a circularity of 2 by incorporating into “A Image-kun” (Asahi Kasei Engineering Co., Ltd.) and conducting particle analysis.

  In the present specification, the content of particles having a circularity of 0.95 or more obtained by an image analysis method means the number ratio of particles having a circularity of 0.95 or more.

<1-6. Aspect ratio>
The deformed silica powder has an aspect ratio obtained by an image analysis method of preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less. The aspect ratio preferably exceeds 1.2.

  An aspect ratio of 4.0 or less is preferred because the viscosity does not increase during synthesis and is easy to handle. Further, even in the resin composition filled with the irregular shaped particles, the viscosity does not increase and the fluidity is maintained. If it exceeds 1.2, it contributes to the bending strength and adhesive strength in the resin after molding.

  In the present specification, the aspect ratio obtained by the image analysis method is the maximum length between two arbitrary points of individual particles by taking an image of 500 or more silica particles and analyzing the image. The maximum length that is the height and the minimum width that is the width in the direction perpendicular to the maximum length are obtained, calculated as the ratio of the maximum length to the minimum width (maximum length / minimum width), and averaged.

  Specifically, the ratio of the maximum length to the minimum width is determined by taking a bright field-scanning transmission image (BF-STEM) for each silica particle using FE-SEM and using the image analysis software “ It can be obtained as maximum / minimum by taking in A image-kun (Asahi Kasei Engineering Co., Ltd.) and conducting particle analysis.

<1-7. Content of metal impurities>
The deformed silica powder preferably has a low content of metal impurities. If the content of metal impurities is small, it is possible to suppress the occurrence of problems such as short-circuiting of metal wiring when mounted on a semiconductor device as a sealing material.

  Specifically, the deformed silica powder preferably has a sodium, potassium and iron content of less than 1 ppm.

  In addition, in the conventional deformed silica, spherical primary particles are aggregated to obtain irregular secondary particles, and therefore metal salts or the like may be used as a flocculant. In this case, the amount of metal impurities is relatively large. On the other hand, since the irregular shaped silica powder is obtained by grain growth using irregular shaped silica as a core, as described later, a flocculant is unnecessary. Therefore, the deformed silica powder has a very low content of metal impurities as described above.

  In this specification, content of sodium and potassium means the value measured using the ion chromatography system. The iron content means a value measured using an ICP emission analyzer.

<1-8. Hydrophobicity (M value)>
The deformed silica powder can also have hydrophobicity by a hydrophobization treatment described later. The degree of “hydrophobicity” can also be expressed using the degree of hydrophobicity. In the present specification, the degree of hydrophobicity may be referred to as an M value.

  The degree of hydrophobicity is preferably 30% by volume or more, and more preferably 35 to 76% by volume. If the degree of hydrophobicity falls within this range, it means that the surface of the hydrophobic deformed silica powder is sufficiently hydrophobized. When this hydrophobic deformed silica powder is added to a hydrophobic resin, it is ensured that the surface of this hydrophobic deformed silica powder is completely wetted and dispersed in the resin without exhibiting non-uniformity such as phase separation.

  If the degree of hydrophobicity falls within this range, it means that the surface of the hydrophobic deformed silica powder is sufficiently hydrophobized. When the hydrophobic silica powder of the present invention is added to a hydrophobic resin, the surface of the hydrophobic silica powder is completely wetted and dispersed in the resin without exhibiting non-uniformity such as phase separation. Guarantee.

  In the present specification, the degree of hydrophobicity means a value obtained by the following method. After weighing 50 mL of water into a 200 mL capacity beaker, 0.2 g of a silica powder sample was added. While stirring this with a magnetic stirrer, methanol was added dropwise with a burette, and titration was performed with the end point being the point at which the total amount of the charged silica powder was wetted and suspended in the solvent in the beaker. At this time, the solution was introduced into the solvent using a tube so that methanol did not directly contact the charged silica powder sample. And the value of the volume% of methanol in the methanol-water mixed solvent at the titration end point was defined as the degree of hydrophobicity (M value).

<1-9. True specific gravity>
The deformed silica powder preferably has a true specific gravity in the range of 1.80 to 2.17. The same applies to the above-mentioned hydrophobic silica powder having hydrophobicity. That the true specific gravity is in this range indicates that the specific gravity is smaller than that of general dry silica. In general, silica obtained by a sol-gel method has a lower true specific gravity than dry silica. The true specific gravity is a value measured by a dry automatic densimeter.

[Embodiment 2]
In another aspect, the deformed silica powder is a core-shell deformed silica powder composed of a core part and a shell part covering the core part, and the core part is made of fumed silica. The shell portion is a silica layer obtained by a sol-gel method, and the saturated water content measured by a loss on drying method at 120 ° C. may be 1.5% by mass or less. The deformed silica powder has a structure obtained by using a deformed fumed silica as a core portion and grain-growing it. Therefore, the irregular shaped silica powder is irregular and does not contain substantially spherical silica particles.

  Fumed silica is a kind of dry silica, and generally has a complicated shape formed by fusing primary particles in a bead shape. In the present invention, the fumed silica serving as the core portion is not particularly limited, and known ones can be used.

For example, it is preferable that the BET specific surface area in the said fumed silica is 70-330 m < ² > / g. Moreover, it is preferable that the average primary particle diameter in the said fumed silica is 7-22 nm. What is necessary is just to select suitably according to the target particle size.

  The shell part is a silica layer obtained by the sol-gel method as described above. In this specification, the “sol-gel method” means, for example, [2. <2-1. Method for producing irregular shaped silica powder]. Means the method described in the step of producing silica powder>.

  The saturated water content is <1-4. As described in Saturated water content>.

  In the present invention, the surface of the shell portion may be further surface treated. The surface treatment is, for example, [2. <2-7. Manufacturing method of deformed silica powder]. A state where the surface is treated by the method described in <Surface treatment> can be mentioned.

In addition, as shown in Embodiment 1, the deformed silica powder has a median diameter of the weight-based particle size distribution measured by the centrifugal sedimentation method in the range of 50 to 1000 nm, and the area obtained by the image analysis method (S ) And the envelope area (S ₀ ) obtained by the image analysis method (S / S ₀ ) is in the range of 0.60 to 0.95, and the maximum of the weight-based particle size distribution obtained by the centrifugal sedimentation method A deformed silica powder having one (peak) and a geometric standard deviation σg of 1.5 or less may also be included. That is, the deformed silica powder may include the deformed silica powder having the physical properties shown in the first embodiment.

[2. Method for producing irregular shaped silica powder]
The method for producing the irregular shaped silica powder (hereinafter, also simply referred to as “the present production method”) comprises adding an alkoxysilane or a hydrolyzate thereof and / or a partial condensate thereof to a fumed silica dispersion to cause a polycondensation reaction. A step of producing silica particles. That is, this manufacturing method should just include the process of making a grain grow by making fumed silica which is a deformed shape into a nucleus. The silica powder obtained by this production method is irregular. Furthermore, the content of spherical silica particles in the obtained irregular shaped silica powder is extremely low.

  That is, according to this manufacturing method, the above-mentioned [1. The deformed silica powder described in [Modified silica powder] can be obtained. In addition, [1. Regarding the matters already described in [Modified silica powder], the description is omitted below, and the above description is used as appropriate.

  FIG. 4 is a schematic diagram comparing a method for producing deformed silica powder according to an embodiment of the present invention and a conventional method for producing spherical silica powder. FIG. 4A shows a conventional method for producing spherical silica powder. FIG. 4B shows a method for producing deformed silica powder according to an embodiment of the present invention.

The silica powder is obtained, for example, by a reaction of obtaining SiOH ₄ by hydrolysis from Si (OCH ₃ ) ₄ and obtaining SiO ₂ by polycondensation. In the conventional method for producing spherical silica powder, first, as shown in (i) of FIG. 4 (a), a reaction solution 18 containing a basic catalyst and a solvent is charged. And as shown to (ii) of (a) of FIG. 4, a basic catalyst, alkoxysilane, etc. are added and the nucleus particle 19 is produced | generated by a nucleation reaction. Thereafter, as shown in (iii) of FIG. 4A, spherical silica particles 15 having an increased particle diameter are obtained by a nucleus growth reaction. On the other hand, in the case of this production method, as shown in (i) of (b) of FIG. 4, irregularly shaped fumed silica is used as a core particle (starting material). In this manufacturing method, as shown in (ii) of FIG. 4B, first, the deformed core particles 20 are charged together with the reaction liquid 18. Thereafter, as shown in (iii) of FIG. 4 (b), a deformed silica powder (deformed silica particles) 1 having an increased particle size is obtained by a nucleus growth reaction.

  FIG. 5 is a schematic diagram comparing a method for producing deformed silica powder according to an embodiment of the present invention and a conventional method for producing deformed silica powder. FIG. 5 (a) shows a conventional method for producing irregular shaped silica powder. FIG. 5B shows a method for producing a deformed silica powder according to an embodiment of the present invention.

  In the conventional method for producing irregular shaped silica powder, first, as shown in (i) of (a) of FIG. 5, spherical core particles are generated. And as shown to (ii) of (a) of FIG. 5, the said spherical core particle is aggregated. Thereafter, as shown in (iii) of FIG. 5 (a), large-shaped irregular shaped silica particles are obtained by grain growth. However, in this case, a certain amount of large-sized spherical silica particles derived from spherical core particles that have not been aggregated remain. Therefore, in the conventional method for producing irregular shaped silica powder, the particle size distribution becomes wide as described above. The techniques described in Patent Documents 2 and 3 described above correspond to the manufacturing method shown in FIG. On the other hand, in the case of this production method, as shown in (i) of (b) of FIG. 5, irregularly shaped fumed silica is used as the core particles. Then, as shown in (ii) of FIG. 5 (b), irregularly shaped silica particles having an increased particle diameter are obtained by grain growth of the core particles. Therefore, in the case of this production method, the content of spherical silica particles is extremely small.

<2-1. Process for producing silica particles>
In this step, silica particles are produced by adding alkoxysilane or a hydrolyzate thereof and / or a partial condensate thereof to the fumed silica dispersion and subjecting it to a polycondensation reaction. That is, in this step, fumed silica is grown by a sol-gel method to obtain a reaction liquid in which irregular-shaped silica particles are suspended. In this step, since fumed silica is used as the core particles, irregularly shaped silica particles can be obtained. In addition, since spherical silica particles are not used as core particles, the obtained deformed silica powder has a very small content of spherical silica particles.

  The dispersibility index of the fumed silica dispersion is preferably 2.5 or more, more preferably 2.6 or more, further preferably 2.7 or more, and 2.8 or more. It is particularly preferred. A dispersibility index of 2.5 or more is preferable because fumed silica is sufficiently dispersed without agglomeration in the dispersion. In the present specification, the dispersibility index means a value measured by a method described in Examples described later.

(Fumed silica)
The fumed silica contained in the fumed silica dispersion is the above-mentioned [1. If it is fumed silica demonstrated by the irregular-shaped silica powder], it will not specifically limit.

(solvent)
Examples of the solvent in the fumed silica dispersion include polar solvents. In this specification, the polar solvent means water or an organic solvent that dissolves 10 g or more of water per 100 g under normal temperature and normal pressure. A plurality of organic solvents other than water may be mixed and used as the solvent. In this case, the mixture of the organic solvents only needs to satisfy the above requirements.

  Examples of the organic solvent include alcohols such as methanol, ethanol, isopropyl alcohol and butanol; ethers such as diethyl ether, tetrahydrofuran and dioxane; amide compounds such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone.

  Alcohol is a by-product generated during the sol-gel process, so use of alcohols such as methanol, ethanol, isopropyl alcohol, or butanol among the above causes unnecessary impurities to be mixed into the dispersion after the reaction. It is particularly preferable from the viewpoint of suppression and the point that it can be easily removed by heating.

  The above solvents can be used alone or as a mixture of two or more solvents.

  The use ratio of the solvent may be appropriately determined according to desired values of the particle size and concentration of the target silica particles. For example, when alcohol is used as the organic solvent, the proportion of alcohol in the mass (100% by mass) of the dispersion of silica particles obtained by the sol-gel reaction is preferably 10 to 90% by mass, more preferably 15 to 80% by mass. Used to be in the range of%.

  Water may be used as a part or all of the solvent, and may be added to the reaction solution after preparing all reaction raw materials other than water. However, in order to advance the reaction of the sol-gel method quickly and stably, it is preferable to use water as a part of the solvent, that is, to use a mixture of water and an organic solvent as the solvent. Here, water as a solvent is a concept including a case where it is added along with addition of a basic catalyst.

  The use ratio of water is appropriately adjusted and selected according to the particle size of the silica particles to be produced. If the proportion of water used is too small, the reaction rate becomes slow. Conversely, if too much water is used, it takes a long time for drying (solvent removal). Therefore, the proportion of water used is selected in consideration of both of these requirements. The ratio of water used is preferably in the range of 2 to 50% by mass and preferably in the range of 5 to 40% by mass with respect to the total mass of the dispersion of silica particles obtained by the sol-gel method reaction. More preferred.

(Basic catalyst)
A basic catalyst may be added to the fumed silica dispersion. By using a basic catalyst, the hydrolysis reaction and / or condensation reaction of alkoxysilane can be promoted. As a basic catalyst, if it is a well-known basic catalyst used for manufacture of the inorganic oxide particle by reaction of a sol-gel method, this can be used conveniently. Examples of such basic catalysts include amine compounds and alkali metal hydroxides. In particular, it is preferable to use an amine compound from the viewpoint that the amount of impurities is small and high-purity silica particles can be obtained. Examples of such amine compounds include ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, dimethylamine, and trimethylamine. Among these, it is particularly preferable to use ammonia because it is highly volatile and easy to remove and the reaction rate of the sol-gel method is fast. The basic catalyst can be used alone or in combination of two or more.

  As the basic catalyst, an industrially available catalyst can be used as it is (as it is in a commercially available form). For example, it can be diluted with water or an organic solvent such as ammonia water. It is also possible to use it. In particular, it is preferable to use the aqueous solution in which the basic catalyst is diluted with water and the concentration is adjusted as necessary, in terms of easy control of the reaction progress rate. When an aqueous solution of a basic catalyst is used, it is preferable to use an aqueous solution having a concentration in the range of 1 to 30% by mass because it is easily available industrially and concentration adjustment is easy.

  What is necessary is just to determine the addition amount of a basic catalyst suitably considering the hydrolysis of alkoxysilane and the reaction rate of a polycondensation reaction. As the addition amount of the basic catalyst, the amount of the basic catalyst in the reaction solution is preferably 0.1 to 60% by mass with respect to the mass of the alkoxysilane used, and 0.5 to 40% by mass. It is more preferable to use in the range of%.

(Alkoxysilane)
Examples of the alkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane. From the viewpoint of being easily available industrially and from the viewpoint of easy handling, the alkoxysilane is preferably methyltrimethoxysilane, tetramethoxysilane, or tetraethoxysilane, and tetramethoxysilane or tetraethoxysilane. More preferably, it is ethoxysilane. In addition, as said alkoxysilane, only 1 type may be used and 2 or more types may be used together. In this step, a hydrolyzate of alkoxysilane may be added, or an alkoxysilane or a partial condensate of the hydrolyzate may be added.

(Reaction conditions)
This step can be performed, for example, as follows. An example is a method in which fumed silica, a solvent, and a basic catalyst are charged into a reaction vessel, and an alkoxysilane (or an organic solvent solution of alkoxysilane) and an aqueous solution of a basic catalyst are simultaneously added thereto. According to this method, silica particles having good reaction efficiency and a small particle size distribution can be produced efficiently and with good reproducibility, which is preferable. When two or more types of alkoxysilane are used in combination, they may be mixed and added simultaneously, or each may be added sequentially.

  It is preferable to add the alkoxysilane and the basic catalyst dropwise to the reaction solution. Here, dripping in the liquid means that the tip of the dripping port is immersed in the reaction liquid when the alkoxysilane and the basic catalyst are dropped into the reaction liquid. The position of the tip of the dripping port is not particularly limited as long as it is in the liquid, but it should be a position where stirring is sufficiently performed, such as in the vicinity of the stirring blade, and the dripping material can quickly diffuse into the reaction liquid. desirable.

  The addition time of alkoxysilane and basic catalyst (the time from the start of addition to the end of addition) is preferably, for example, within 48 hours. For example, if the addition time is 0.2 hours or more, the width of the particle size distribution can be reduced. Moreover, if the said addition time is 48 hours or less, the stable grain growth can be performed.

  The reaction temperature is not particularly limited as long as the reaction of the sol-gel method proceeds rapidly, and may be appropriately selected according to the particle size of the target silica particles. In general, the lower the reaction temperature, the larger the particle size of the silica particles obtained. For example, the reaction temperature may be appropriately selected within the range of −10 to 60 ° C.

  In order to advance the reaction of the sol-gel method with certainty, after the dropping of the alkoxysilane and the basic catalyst is completed, ripening (a period of time is required until the next hydrophobizing agent is added) may be performed. In this case, the aging temperature is preferably about the same as the reaction temperature, that is, −10 to 60 ° C. The aging time is preferably 0.25 to 5 hours.

<2-2. Coagulation of silica particles>
This manufacturing method is <2-1. A step of adding a coagulant to the reaction liquid in which the deformed silica particles obtained by the step described in the step of producing silica particles is suspended may be included. By adding the coagulant to the reaction solution, an aggregate (cake) in which silica particles are aggregated with a weak force in the reaction solution is formed. Due to the presence of the coagulant or derivative thereof, it is possible for such aggregates to exist stably in the reaction solution, and it is possible to prevent the formation of strongly aggregated aggregates. In this step, by forming an aggregate, silica particles can be easily recovered by filtration.

  Examples of the coagulant include carbon dioxide, ammonium carbonate, ammonium hydrogen carbonate, and ammonium carbamate. These coagulants are preferable because there is no possibility that metal impurities are mixed as compared with the case of using a metal salt as the coagulant. Moreover, since the coagulant is easily decomposed and removed by slight heating, it is possible to easily produce a high-purity deformed silica powder.

  As the coagulant, it is preferable to use at least one selected from the group consisting of ammonium hydrogen carbonate and ammonium carbamate, more preferably ammonium hydrogen carbonate, and ammonium hydrogen carbonate added as an aqueous solution. Is more preferable. The coagulant may be used alone or in combination of two or more.

  The amount and method of addition of the coagulant can be set as follows according to the type of coagulant used. The addition amount of the coagulant is set by taking into consideration the balance between the degree of formation of weak aggregates of silica particles in the reaction solution and the waste of using an excessively large amount of raw material. The mass of the silica particles as a reference for the amount of the coagulant added below is a conversion value when it is assumed that all of the alkoxysilane used has been hydrolyzed and polycondensed.

  When carbon dioxide is used as the coagulant, the amount added is preferably 15 parts by mass or more with respect to 100 parts by mass of silica particles contained in the reaction solution, and is 15 to 300 parts by mass. It is more preferable, and it is still more preferable that it is 17-200 mass parts.

  Examples of the method of adding carbon dioxide include a method of blowing into a reaction solution in a gaseous state and a method of adding in a solid state (dry ice). From the viewpoint of easy operation, it is preferable to add carbon dioxide in a solid state.

  When ammonium carbonate, ammonium hydrogen carbonate or ammonium carbamate is used as the coagulant, the amount added is preferably 15 parts by mass or more with respect to 100 parts by mass of silica particles contained in the reaction solution. More preferably, it is 15-80 mass parts, More preferably, it is 17-60 mass parts, It is especially preferable that it is 20-50 mass parts.

  Ammonium carbonate, ammonium hydrogen carbonate or ammonium carbamate may be added in a solid state or in a solution state dissolved in a suitable solvent. The solvent used in the case of adding these in a solution state is not particularly limited as long as it dissolves them, but water is used from the viewpoint of high dissolving ability and easy removal after filtration. It is preferable to use it. The concentration of the ammonium carbonate, ammonium hydrogen carbonate or ammonium carbamate solution is not particularly limited as long as these are in the range in which they are dissolved, but is preferably 2 to 15% by mass, and more preferably 5 to 12% by mass. If it is the said density | concentration, the usage-amount of a solution is not too much and it is economical.

  In particular, a mixture of ammonium hydrogen carbonate and ammonium carbamate, which is commercially available as so-called “ammonium carbonate”, can be used as it is or as a solution in an appropriate solvent. In this case, the total amount of ammonium bicarbonate and ammonium carbamate, and the type and concentration of the solvent used in the case of adding this as a solution are the same as those of ammonium carbonate, ammonium bicarbonate, or ammonium carbamate. In some cases, the same as described above.

  In this step, the temperature at which the coagulant is added to the reaction solution of silica particles is not particularly limited as long as the aggregate in which the generated silica particles are aggregated with a weak force can be stably present. Set it. In consideration of the decomposition temperature of the coagulant, etc., it is usually −10 to 60 ° C., preferably 10 to 40 ° C., which is the same as the reaction temperature.

  It is preferable to perform aging after adding the coagulant (that is, to leave a certain interval before filtration in the next step). By aging after the addition of the coagulant, formation of the above-mentioned weak aggregates of silica particles is promoted, which is preferable. The aging time is preferably 0.5 to 72 hours, more preferably 1 to 48 hours. If the aging time is 0.5 hours or more, the formation of aggregates can be promoted sufficiently. Moreover, if the aging time is 72 hours or less, it is economical. The temperature of the reaction solution at the time of aging is not particularly limited, and the reaction can be carried out in the same temperature range as that at the time of adding the coagulant.

<2-3. Recovery of silica particles>
This manufacturing method is <2-1. Process for producing silica particles> to <2-2. A step of recovering the silica particles from the reaction solution containing the silica particles obtained by the step described in the section “Coagulation of silica particles”. The recovery method is not particularly limited, and examples thereof include filtration, a method of volatilizing the dispersion medium, and a method of decanting after the silica particles are precipitated by a centrifuge. Especially, filtration is preferable at the point which can collect | recover silica particles easily.

  The filtration method is not particularly limited, and known methods such as vacuum filtration, pressure filtration, and centrifugal filtration can be applied.

  The filter paper, filter, filter cloth, etc. used in the filtration (hereinafter collectively referred to as “filter paper”) can be used without particular limitation as long as they are industrially available. What is necessary is just to select suitably according to the scale of (filter). Since the silica particles to be collected in this production method are secondary particles, the pore diameter of filter paper or the like may be much larger than the primary particle diameter. Therefore, it is possible to filter quickly.

The silica particles are recovered as a cake by filtration. By rinsing the obtained cake with an appropriate solvent (for example, water or alcohol), the solvent and basic catalyst used in the reaction by the sol-gel method can be decomposed and removed.
When there is a possibility that the coagulant or the derivative thereof may disappear due to the rinsing, the coagulant may be added as appropriate so that the coagulant or the derivative in the cake does not disappear.

As a method for recovering silica, even when the coagulant or its derivative may be lost during recovery, such as a method of volatilizing the dispersion medium, the aggregate (cake) of the silica particle reaction liquid during recovery may be A coagulant may be added as appropriate so that the coagulant or derivative thereof does not disappear in the aggregate (cake).
<2-4. Drying of silica particles>
This manufacturing method is <2-3. You may include the process of drying the silica particle obtained from the process demonstrated by collection | recovery of a silica particle. As a drying method, a known method is not particularly limited and is employed. For example, drying methods such as reduced pressure drying in a heated state and blow drying are exemplified.

  The temperature at the time of drying is not particularly limited as long as the dispersion medium can be removed and the salt derived from the coagulant can be decomposed, and may be appropriately determined in consideration of the pressure at the time of drying. Specifically, the drying temperature is 35 to 250 ° C, more preferably 50 to 250 ° C.

In the present invention, when recovering and drying the silica particles from the reaction solution containing the silica particles, the dispersion medium can be removed continuously by concentration and drying. For example, by directly concentrating the reaction liquid containing silica particles by a method of volatilizing the dispersion medium by heating concentration or vacuum concentration, silica particles from which the dispersion medium has been removed are directly obtained from the reaction liquid containing silica particles. Can do. In this case, when the dispersion medium is removed by heating, the coagulant or its derivative may be lost. In such a case, the aggregate (cake) of the reaction solution containing silica particles during concentration and drying is used. The coagulant may be added as appropriate so that the coagulant or the derivative thereof does not disappear in the aggregate (cake).
<2-5. Firing of silica particles>
In general, silica obtained by the sol-gel method has a large amount of silanol groups on the silica surface, and therefore its saturated water content is about 8% by mass. The production method of the present invention includes a step of firing the silica particles recovered from the reaction solution for the purpose of reducing the saturated water content.

  The firing temperature is preferably 300 to 1300 ° C, more preferably 600 to 1200 ° C. If it is too low, the dehydration condensation reaction of silanol groups will not proceed, so that the saturated water content cannot be reduced sufficiently, and if it is too high, the silica particles will be fused.

  The firing time is not particularly limited as long as it reaches the target saturated moisture content, but it is uneconomical if it is too long, so after raising the temperature to the target firing temperature, 0.5 to 48 hours, more preferably, It is sufficient to hold and calcinate in the range of 2 to 24 hours.

The atmosphere during firing is not particularly limited, and can be performed under an inert gas such as argon or nitrogen, or in an air atmosphere. The deformed silica powder obtained after the baking treatment has a high purity and a reduced saturated water content, and therefore is suitable as a filler for a sealing material.
<2-6. Disintegration of silica particles>
The manufacturing method of this invention includes the process of crushing the silica particle obtained from the baking process. Since the silica particles obtained after the baking treatment contain aggregated particles, they are used after being crushed by a known crushing means such as a jet mill.

The conditions for crushing using a jet mill are not particularly limited, but air or an inert gas such as N ₂ is used as the compressed gas, and the powder concentration in the gas is 10 g / m ³ or more and 220 g / m. It is preferably carried out so as to be ³ or less, preferably 15 g / m ³ or more and 190 g / m ³ or less, more preferably 15 g / m ³ or more and 30 g / m ³ or less. The higher the powder concentration, the better the crushing ability, but even if the powder concentration is too high, the crushing force applied to the individual particles is dispersed and the crushing efficiency decreases, so the powder concentration is in the above range. Is preferred. When it is difficult to obtain the above-mentioned powder concentration, it may be pulverized until the desired powder physical properties are obtained by repeatedly pulverizing the pulverized one. Of course, the above-described jet mill pulverization is merely an example, and other known devices such as pulverization, pulverization, and classification may be appropriately selected.

  The silica powder obtained by pulverization can further remove coarse particles and the like using a sieve or the like. The silica powder from which the coarse particles have been removed is suitably used as a filler for a semiconductor device encapsulant that is becoming narrower and more highly integrated.

<2-7. Surface treatment>
This production method is <2-6. With respect to the silica particles obtained from the process described in <Crushing of silica particles>, a known surface treatment agent such as silicone oil, silane coupling agent, silazane, titanate coupling agent, aluminum coupling agent or the like is used. It is also possible to perform surface treatment and use it for the intended purpose. Of these, silicone oil, silane coupling agent, and silazane are particularly preferably used.

  The silicone oil used in the present invention can be a known silicone oil usually used for surface treatment without particular limitation, and can be appropriately selected according to the performance of the surface-treated silica particles required, Use it. Specific examples include dimethyl silicone oil, methyl phenyl silicone oil, methyl hydrogen silicone oil, alkyl modified silicone oil, amino modified silicone oil, epoxy modified silicone oil, carboxyl modified silicone oil, carbinol modified silicone oil, methacryl modified. Examples thereof include silicone oil, polyether-modified silicone oil, and fluorine-modified silicone oil. Among these, dimethyl silicone oil is preferably used for the purpose of simply hydrophobizing.

  The amount of silicone oil used is not particularly limited. However, if the amount is too small, the surface treatment becomes insufficient, and if the amount is too large, the post-treatment becomes complicated. To 30 parts by mass, more preferably 0.1 to 20 parts by mass.

As the silane coupling agent used in the present invention, a known silane coupling agent usually used for surface treatment can be used without any particular limitation, and it is appropriately selected according to the performance of the surface-treated silica particles required. Select and use. Specifically, methyltrimethoxysilane, methyltriethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxymethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycyl Sidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltri Toxisilane, 3-acryloxypropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N- (2-aminoethyl) ) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N, N-dimethyl-3-aminopropyltri Examples include methoxysilane, N, N-diethyl-3-aminopropyltrimethoxysilane, 4-styryltrimethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane.
Among these, from the viewpoint of dispersibility with the resin to be filled, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-acryloxypropyl Trimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane are preferably used.
For the purpose of simply hydrophobizing, it is preferable to use methyltrimethoxysilane, methyltriethoxysilane, hexyltrimethoxysilane, or decyltrimethoxysilane.

  The amount used when using the silane coupling agent is not particularly limited, but if it is too small, the surface treatment becomes insufficient, and if it is too large, the post-treatment becomes complicated. It is good to set it as 0.05-40 mass parts, More preferably, it is 0.1-30 mass parts.

  As the silazane used in the present invention, a known silazane usually used for surface treatment can be used without particular limitation. Among silazanes, hexamethylsilazane is preferably used because of its particularly good reactivity and ease of handling.

  The amount of silazane used is not particularly limited, but if it is too small, the surface treatment will be insufficient, and if it is too large, the post-treatment will be complicated, so 0.05 mass with respect to 100 parts by mass of the silica particles used. It is good to set it as -60 mass parts, More preferably, it is 0.1-50 mass parts.

  These surface treatment agents may be used alone or in combination of two or more. In addition, processing can be performed in multiple stages.

[3. Resin composition]
In the present invention, a resin composition containing the deformed silica powder is also provided. The type of the resin is not particularly limited, and examples thereof include an epoxy resin, an acrylic resin, a silicone resin, a polyester resin, a urethane resin, and an olefin resin. Among them, the epoxy resin is preferably used as an adhesive / sealing resin.

  When the resin composition of the present invention is used as a semiconductor encapsulant, the deformed silica particles used as a filler do not have a crushing surface, which may cause damage to the semiconductor element surface and wires and wear of the mold. In addition, compared with the case where crushed silica is used, the viscosity at the time of dispersion is low and the fluidity is excellent, so that the filling rate can be kept high and the solder reflow resistance is excellent.

  On the other hand, since the silica particles used as the filler have irregularities, the contact point between the particles or the adhesive member is increased compared to conventional spherical silica, so that stable bending strength and adhesive strength in the resin after molding. Can be obtained.

  In addition, the above-mentioned deformed silica powder is used as an antiblocking agent and is preferably used as a resin composition for a film by being dispersed in an olefin resin or the like. The deformed silica powder in the resin composition is characterized by excellent dispersibility because it does not have a crushed surface and excellent adhesion to the resin because it has irregularities, and is difficult to drop off.

  The manufacturing method of the said resin composition will not be specifically limited if the unusual shape silica powder of this invention is used as a filler, The manufacturing method of a well-known resin composition is used suitably. As an additive to the resin, not only the deformed silica powder of the present invention but also a combination with existing silica powder may be used.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to a following example. In addition, various physical property measurements in the following examples are based on the following methods.

[Method for measuring physical properties]
(1) Median diameter and local maximum (peak) of weight-based particle size distribution, and geometric standard deviation σg
(Measurement sample preparation)
A 2-propanol suspension in which the concentration of silica as a measurement sample was 1.5% by mass was prepared as follows. 0.3 g of silica powder and 20 g of 2-propanol were placed in a glass sample tube bottle (manufactured by ASONE Co., Ltd., inner volume 30 mL, outer diameter about 28 mm). The sample tube bottle containing the sample was placed so that the probe tip surface of an ultrasonic cell crusher (manufactured by BRANSON, model Sonifier II Model 250D, probe: 1/4 inch) was 15 mm below the water surface. Using this ultrasonic cell disrupter, silica powder is dispersed in 2-propanol under the conditions of an output of 20 W and a dispersion time of 45 minutes, and a 2-propanol suspension in which the concentration of silica as a measurement sample is 1.5% by mass. A liquid was prepared.

(Measuring method)
The median diameter and particle size distribution were measured using a disk centrifugal sedimentation type particle size distribution analyzer (CPS, model number DC-24000). The measurement conditions were calibrated for each measurement with 0.476 μm PVC particles at a rotation speed of 18000 rpm and a silica true density of 2.1 g / cm ³ . The geometric standard deviation σg of the particle size distribution was calculated from the weight-based particle size distribution obtained by logarithmic average distribution fitting (least square method) in the range of the cumulative frequency of 10% by mass to 90% by mass.

(2) The ratio (S / S ₀ ) of the area (S) obtained by the image analysis method and the envelope area (S ₀ ) obtained by the image analysis method, the average circularity of the particles, and the circularity of 0.95 Content of the above particles (Measurement method)
Using a FE-SEM (model number S-5500, manufactured by Hitachi High-Technologies Corporation) for 500 or more silica particles, a bright field-scanning transmission image (BF-STEM) was photographed at an acceleration voltage of 30 kV and a magnification of 20000 times. . The photographed images were taken into image analysis software “A Image-kun” (manufactured by Asahi Kasei Engineering Co., Ltd.), and particle analysis was performed with the particle analysis parameters as follows.
Particle brightness: Dark binarization method: Manual shrinkage Separation frequency: 20 times Small figure: 0
Noise removal filter: Shading: Result display unit: nm
By particle analysis, the area (S) of each particle, the envelope area (S ₀ ) (the area surrounded by the envelope connecting the convex portions of the particles), and the aspect ratio were determined. Furthermore, the ratio (S / S ₀ ) between the area of each particle and the envelope area was determined. Moreover, the circularity of each particle | grain was computed from following formula (1) using the area and perimeter of each particle | grain.

Circularity = 4π × area / (perimeter) ² (1)
The ratio of the area to the envelope area (S / S ₀ ), the average circularity, and the aspect ratio are the ratio (S / S ₀ ), circularity, and aspect of the area and envelope area of each particle obtained by the image analysis. The average of the ratio was taken and obtained. Further, the number ratio of particles having an area to envelope area ratio (S / S ₀ ) of 0.97 or more and the number ratio of particles having a circularity of 0.95 or more were obtained.

(3) Saturated water content The saturated water content was measured by the following method. 10 g of silica powder was dried at 120 ° C. for 24 hours, and then cooled in a desiccator containing silica gel. Subsequently, the particles cooled in the desiccator were allowed to stand for 48 hours in an environment of 25 ° C. and 50% RH, and the mass (Dwet) of the particles was weighed. The weighed particles were dried again at 120 ° C. for 24 hours, and the mass (Ddry) of the particles was weighed. The value calculated by the following mathematical formula (2) from the change in mass before and after humidity control was taken as the saturated moisture content.

Saturated water content (mass%) = ((Dwet−Ddry) / Ddry) × 100 Formula (2)
(4) Hydrophobicity (M value)
After weighing 50 mL of water into a 200 mL capacity beaker, 0.2 g of a silica powder sample was added. While stirring this with a magnetic stirrer, methanol was added dropwise with a burette, and titration was performed with the end point being the point at which the entire amount of the added silica powder was wetted and suspended in the solvent in the beaker. At this time, the silica powder sample was introduced into the solvent by a tube so that methanol did not directly contact the charged silica powder sample. And the value of the volume% of methanol in the methanol-water mixed solvent at the titration end point was defined as the degree of hydrophobicity (M value).

(5) True specific gravity Using a dry automatic densimeter (manufactured by Shimadzu Corporation, model number Accupic II 1340 series), measurement was performed using a 10 cc cell.

(6) Content of sodium, potassium and iron <Content of sodium and potassium>
(Measurement sample preparation)
5 g of silica powder was added to 50 g of ultrapure water and heated at 120 ° C. for 24 hours using a Teflon (registered trademark) decomposition vessel. Ultrapure water and silica powder were weighed to the nearest 0.1 mg. Thereafter, the silica solid content was separated using a centrifugal separator to obtain a sample for ion chromatography measurement. In addition, the said operation was performed only with ultrapure water and the blank sample was obtained.

(Measurement)
The concentration of sodium and potassium in the measurement sample was measured using an ion chromatography system (manufactured by Nippon Dionex Co., Ltd., model number ICS-2100). The contents of sodium and potassium in the silica powder were calculated using the following formula (3).

C _Silica = (C _Sample −C _Blank ) × M _PW / M _Silica (3)
C _Silica : ion concentration in silica (ppm)
C _Sample : ion concentration (ppm) in the measurement sample
C _Blank : Ion concentration (ppm) in the blank sample
M _PW : Amount of ultrapure water (g)
M _Silica : Silica weight (g)
In addition, all C _Blank of each ion was 0 ppm.

<Iron content>
2 g of silica powder after drying was precisely weighed and transferred to a platinum dish, and 10 mL of concentrated nitric acid and 10 mL of hydrofluoric acid were added in this order. This was placed on a hot plate set at 200 ° C. and heated to dry the contents. After cooling to room temperature, 2 mL of concentrated nitric acid was further added, and the mixture was placed on a hot plate set at 200 ° C. and heated to dissolve. After cooling to room temperature, the solution as the contents of the platinum dish was transferred to a 50 mL volumetric flask, diluted with ultrapure water, and aligned with the marked line. Using this as a sample, the iron content was measured with an ICP emission analyzer (manufactured by Shimadzu Corporation, model number ICPS-1000IV).

(7) Dispersibility index of fumed silica dispersion A dispersion composed of fumed silica and methanol is placed in a measurement sample cell (manufactured by Tokyo Glass Co., Ltd., synthetic cell, 5-sided transparent, 10 × 10 × 45H). The absorbance τ ₇₀₀ and τ ₄₆₀ of the dispersion were determined using a spectrophotometer (manufactured by JASCO Corporation, model number V-630). The dispersibility index n of the dispersion was calculated using the following formula (4).

n = 2.382 × ln (τ ₄₆₀ / τ ₇₀₀ ) (4)
Τ ₇₀₀ represents the absorbance of the dispersion with respect to light having a wavelength of 700 nm, and τ ₄₆₀ represents the absorbance of the dispersion with respect to light having a wavelength of 460 nm.

  If the value of the obtained dispersibility index was 2.5 or more, it was judged that fumed silica was sufficiently dispersed without agglomerating in the dispersion.

(8) Viscosity Viscosity evaluation when the silica powder was filled in the polar resin was evaluated by filling the epoxy resin. 20 g of silica powder was added to 25 g of bisphenol A + F type mixed epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., ZX-1059) and kneaded by hand. For untreated silica powder that has not been subjected to any surface treatment including only hydrophobization treatment, 0.25 g of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Silicone, KBM-403) is further added. Kneaded. Each of the resin compositions kneaded by hand was pre-kneaded with a rotating and rotating mixer (manufactured by THINKY, Awatori Kentaro AR-500) (kneading: 1000 rpm, 8 minutes, defoaming: 2000 rpm, 2 minutes). The pre-kneaded resin composition was kneaded using three rolls (manufactured by IMEX, BR-150HCV roll diameter φ63.5). The kneading conditions were such that the kneading temperature was room temperature, the distance between rolls was 20 μm, and the number of kneading was 5 times.

  The viscosity of the kneaded resin composition at a shear rate of 1 s-1 was measured with a rheometer (manufactured by HAAKE, ReoStress).

(9) Adhesive strength 1 g of O-cresol novolac epoxy resin (manufactured by Nippon Kayaku Co., Ltd., EOCN-1020-75) and 1 g of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., Biscoat # 300) are placed in an alumina mortar at 120 ° C. The mixture was heated and reacted to obtain a uniform epoxy acrylate solution. Silica powder 0.5g was added to the said solution, and it rubbed well in the mortar and was disperse | distributed uniformly. For untreated silica powder that has not been subjected to any surface treatment including only hydrophobization treatment, 0.005 g of 3-glycidoxypropyltrimethoxysilane is further added, and it is thoroughly rinsed and dispersed uniformly. It was. After uniform dispersion, 1,3-bis (hydrazinocarboethyl) -5-isopropylhydantoin (Ajinomoto Finetechno, Amicure VDH), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl), respectively -Butanone-1 (manufactured by Ciba Japan, Irgacure 369) and N, N'-tetraethyldiaminobenzophenone were added all at once and mixed well. Finally, 2-phenyl-4-methylimidazole (manufactured by Shikoku Chemicals, Curazole 2P4MZ) was added and further mixed.

  The resin composition obtained by mixing was put into a UV syringe, and kneaded and defoamed with a rotating and rotating mixer (manufactured by THINKY, Awatori Netaro ARE-250) (kneading: 2000 rpm, 2 minutes, defoamed) : 2200 rpm, 5 minutes).

Next, a certain amount of the resin composition is applied on the glass using a dispenser (manufactured by Musashi Engineering Co., Ltd., ML-5000XII), and a pair of similar glasses is laminated on the cross to apply a load. Then, photocuring was performed by applying an ultraviolet irradiation device (365 nm, 5 minutes).
After curing, a wire was attached to the cross glass sample, pulled from above and below, and the adhesion strength was measured using a tensile / compression tester (manufactured by Shimadzu Corporation, EZ-test) (see FIG. 6).

[Example 1]
Fumed silica (trade name QS-30, manufactured by Tokuyama Co., Ltd., BET specific surface area 302 m ² / g, average primary particle size 7 nm) 5.25 g and methanol 520 g were added to a disposable cup (manufactured by ASONE Co., Ltd.) having a capacity of 2 L. I put it in. The disposable cup containing the sample was placed so that the probe tip surface of an ultrasonic cell crusher (Sonifier II Model 250D manufactured by BRANSON, probe: 1/4 inch) was 10 mm from the bottom of the disposable cup. Using the ultrasonic cell crusher, fumed silica was dispersed in methanol under the conditions of an output of 60 W and a dispersion time of 30 minutes to prepare a dispersion. The dispersion prepared by carrying out this operation twice was mixed to obtain a dispersion composed of 10.5 g of fumed silica and 1040 g of methanol. The dispersibility index of the dispersion was 2.82, and it was confirmed that the fumed silica was sufficiently dispersed.

  Subsequently, 1050.5 g of the prepared dispersion and 152 g of 15% by mass ammonia water as the charged ammonia water were charged into a 5 L four-necked flask and stirred at 35 ° C. 705.5 g of tetramethoxysilane as alkoxysilane and 232.2 g of 5% by mass ammonia water as added ammonia water were independently dropped into the liquid. The dropping was carried out by adjusting the speed so as to be completed in 120 minutes. The reaction solution was cloudy at the stage of 10 minutes after the start of dropping, and it was confirmed that the reaction was in progress.

  After completion of the dropwise addition, aging was performed for 30 minutes, and 1000 g of a 10% aqueous ammonium hydrogen carbonate solution was added, followed by stirring for 120 minutes. After 120 minutes, a quantitative filter paper (retained particle size 7 μm) was used, and vacuum filtration was performed to obtain a cake. The filtrate was transparent and no filtration leakage was confirmed. Furthermore, it dried under reduced pressure at 100 degreeC for 16 hours, and obtained 272g of silica powder.

Subsequently, the obtained silica powder was baked in a baking furnace at 900 ° C. for 10 hours. The firing atmosphere was not particularly adjusted, and was performed in an air atmosphere. The obtained fired silica powder was jet milled (manufactured by Nippon Pneumatic Industry Co., Ltd., PJM-100SP), and feed pressure and mill pressure were both 0.60 MPa and compressed air of 1.9 Nm ³ / min. The raw material was supplied at a rate of 36.7 kg / min and crushed at 20 g / m ³ per unit air volume to obtain 210 g of deformed silica powder. The obtained irregular shaped silica powder had a median diameter of 293 nm and an unevenness of 0.81. The viscosity of the resin composition was 80 Pa · s, and the adhesive strength after curing was 24N.

[Example 2]
A modified silica powder was obtained in the same manner as in Example 1 except that the amount of tetramethoxysilane added was changed to 680 g. The obtained irregular shaped silica powder had a median diameter of 262 nm and an unevenness of 0.82. The viscosity of the resin composition was 101 Pa · s, and the adhesive strength after curing was 24N.

Example 3
The addition amount of tetramethoxysilane was changed to 352.8 g, the addition amount of 5 mass% ammonia water as addition ammonia water was changed to 116.1 g, and the dropping time (supply time) thereof was changed to 60 minutes. Except that, a modified silica powder was obtained in the same manner as in Example 1. The obtained irregular-shaped silica powder had a median diameter of 179 nm and an unevenness of 0.77. The viscosity of the resin composition was 212 Pa · s, and the adhesive strength after curing was 27N.

Example 4
A modified silica powder was obtained in the same manner as in Example 3 except that the temperature at the time of stirring the prepared dispersion and the charged ammonia water in a four-necked flask was changed to 40 ° C. The obtained irregular shaped silica powder had a median diameter of 196 nm and an unevenness of 0.75. The viscosity of the resin composition was 176 Pa · s, and the adhesive strength after curing was 29N.

Example 5
The addition amount of tetramethoxysilane was changed to 493.9 g, the addition amount of 5% by mass ammonia water as addition ammonia water was changed to 162.5 g, and the dropping time (supply time) was changed to 84 minutes. Except that, a modified silica powder was obtained in the same manner as in Example 1. The obtained irregular shaped silica powder had a median diameter of 210 nm and an unevenness of 0.79. The viscosity of the resin composition was 139 Pa · s, and the adhesive strength after curing was 24N.

Example 6
A modified silica powder was obtained in the same manner as in Example 1 except that the dripping time (supply time) of alkoxysilane and added ammonia water was changed to 240 minutes. The obtained irregular shaped silica powder had a median diameter of 295 nm and a degree of irregularity of 0.81. The viscosity of the resin composition was 82 Pa · s, and the adhesive strength after curing was 24N.

Example 7
The addition amount of tetramethoxysilane was changed to 220.5 g, the addition amount of 5 mass% ammonia water as addition ammonia water was changed to 72.6 g, and the dropping time (supply time) thereof was changed to 60 minutes. Except that, silica powder was obtained in the same manner as in Example 1. The obtained irregular shaped silica powder had a median diameter of 130 nm and an unevenness of 0.69. The viscosity of the resin composition was 330 Pa · s, and the adhesive strength after curing was 28N.

Example 8
Modified silica in the same manner as in Example 1 except that tetraethoxysilane was added as an alkoxysilane instead of tetramethoxysilane, and the dripping time (supply time) of alkoxysilane and added ammonia water was changed to 180 minutes. A powder was obtained. The obtained irregular shaped silica powder had a median diameter of 301 nm and an unevenness of 0.83. The viscosity of the resin composition was 73 Pa · s, and the adhesive strength after curing was 24N.

Example 9
The input amount of fumed silica was changed to 26.7 g, the addition amount of tetramethoxysilane was changed to 1763.6 g, and the addition amount of 5 mass% ammonia water as added ammonia water was changed to 580.5 g. Except that and the dropping time (supply time) was changed to 300 minutes, a modified silica powder was obtained in the same manner as in Example 1. The obtained irregular shaped silica powder had a median diameter of 283 nm and an unevenness of 0.80. The viscosity of the resin composition was 90 Pa · s, and the adhesive strength after curing was 24N.

Example 10
The use of the product name QS-102 (BET specific surface area 205 m ² / g, average primary particle size 12 nm) manufactured by Tokuyama Co., Ltd. instead of the product name QS-30 manufactured by Tokuyama Co., Ltd. as fumed silica, and A modified silica powder was obtained in the same manner as in Example 1 except that the dropping time (feeding time) of alkoxysilane and added ammonia water was changed to 180 minutes. The obtained irregular shaped silica powder had a median diameter of 315 nm and an unevenness of 0.81. The viscosity of the resin composition was 84 Pa · s, and the adhesive strength after curing was 24N.

Example 11
The use of the product name QS-09 (BET specific surface area 85 m ² / g, average primary particle size 22 nm) manufactured by Tokuyama Co., Ltd. instead of the product name QS-30 manufactured by Tokuyama Co., Ltd. as fumed silica, and A modified silica powder was obtained in the same manner as in Example 1 except that the dripping time (supply time) of alkoxysilane and added ammonia water was changed to 240 minutes. The obtained irregular shaped silica powder had a median diameter of 362 nm and a degree of unevenness of 0.81. The viscosity of the resin composition was 69 Pa · s, and the adhesive strength after curing was 24N.

Example 12
The addition amount of tetramethoxysilane was changed to 1763.6 g, the addition amount of 5 mass% ammonia water as addition ammonia water was changed to 580.5 g, and the dropping time (supply time) was changed to 300 minutes. Except that, silica powder was obtained in the same manner as in Example 1. The obtained irregular shaped silica powder had a median diameter of 410 nm and a degree of irregularity of 0.87. The viscosity of the resin composition was 66 Pa · s, and the adhesive strength after curing was 29N.

Example 13
The product name QS-09 (BET specific surface area 85 m ² / g, average primary particle size 22 nm) manufactured by Tokuyama Co., Ltd. was used in place of the product name QS-30 manufactured by Tokuyama Co., Ltd. as a fumed silica. The addition amount of methoxysilane was changed to 216.5 g, the addition amount of 5 mass% ammonia water as addition ammonia water was changed to 696.6 g, and the dropping time (supply time) thereof was changed to 300 minutes. Except for this, silica powder was obtained in the same manner as in Example 1. The obtained irregular-shaped silica powder had a median diameter of 462 nm and an unevenness of 0.89. The viscosity of the resin composition was 60 Pa · s, and the adhesive strength after curing was 32N.

Example 14
A modified silica powder was obtained in the same manner as in Example 1 except that the concentration of the added ammonia water was changed to 2.6 mass% and the addition amount of the added ammonia water was changed to 226.4 g. The obtained irregular shaped silica powder had a median diameter of 262 nm and an unevenness of 0.81. The viscosity of the resin composition was 100 Pa · s, and the adhesive strength after curing was 24N.

Example 15
A modified silica powder was obtained in the same manner as in Example 1 except that the concentration of the added ammonia water was changed to 9.5% by mass and the added amount of the added ammonia water was changed to 121.9 g. The obtained irregular shaped silica powder had a median diameter of 292 nm and an unevenness degree of 0.81. The viscosity of the resin composition was 81 Pa · s, and the adhesive strength after curing was 24N.

Example 16
400 g of deformed silica powder obtained by the method of Example 1 was placed in a 20 L pressure vessel and heated to 230 ° C. After replacing the inside of the container with a nitrogen atmosphere, the container was sealed under atmospheric pressure, and 20 g of water was sprayed while stirring the particles. Thereafter, stirring was continued for 15 minutes, and then the pressure was released and 120 g of hexamethyldisilazane was sprayed. Further, stirring was continued for 1 hour, and then depressurization was performed to obtain 350 g of hydrophobic irregular-shaped silica powder. The obtained irregular shaped silica powder had a median diameter of 293 nm and an unevenness of 0.81. The viscosity of the resin composition was 39 Pa · s, and the adhesive strength after curing was 39N.

Example 17
Hydrophobic deformed silica powder in the same manner as in Example 15 except that water spraying was not performed and the surface treatment agent to be added was changed from hexamethyldisilazane to 40 g of 3-glycidoxypropyltrimethoxysilane. Got. The obtained irregular shaped silica powder had a median diameter of 293 nm and an unevenness of 0.81. The viscosity of the resin composition was 34 Pa · s, and the adhesive strength after curing was 44N.

Example 18
A hydrophobic deformed silica powder having a surface treated in two stages was obtained in the same manner as in Example 16, except that the hydrophobic deformed silica powder obtained by the method of Example 17 was used. The obtained irregular shaped silica powder had a median diameter of 293 nm and an unevenness of 0.81. The viscosity of the resin composition was 28 Pa · s, and the adhesive strength after curing was 52N.

[Comparative Example 1]
A silica powder was obtained in the same manner as in Example 1 except that fumed silica was not used. That is, as shown in FIG. 4A, after generating nuclei particles by a nucleation reaction, the nuclei were grown to obtain silica powder. The obtained silica powder was spherical silica having a median diameter of 79 nm and an irregularity of 1.00. The viscosity of the resin composition was 498 Pa · s, and the adhesive strength after curing was 13N.

[Comparative Example 2]
The reaction temperature was changed to 25 ° C., the addition amount of tetramethoxysilane was changed to 216.5 g, the addition amount of 5% by mass ammonia water as the added ammonia water was changed to 696.5 g, and these were dropped. A silica powder was obtained in the same manner as in Comparative Example 1 except that the time (supply time) was changed to 380 minutes. The obtained silica powder was spherical silica having a median diameter of 285 nm and an irregularity of 1.00. The viscosity of the resin composition was 81 Pa · s, and the adhesive strength after curing was 18N.

[Comparative Example 3]
Hydrophobic silica particles were obtained in the same manner as in Example 16 except that the silica particles obtained by the method of Comparative Example 2 were used. The obtained silica powder was spherical silica having a median diameter of 285 nm and an irregularity of 1.00. The viscosity of the resin composition was 35 Pa · s, and the adhesive strength after curing was 34N.

〔result〕
From the results of Examples and Comparative Examples above, in the resin composition to which the deformed silica powder of the present invention was added, the viscosity was comparable as compared with the one to which the spherical silica powder having the same particle size was added, and cured. A resin having high adhesive strength later was obtained. Also, the irregular-shaped silica powder having hydrophobicity has the same particle size, and the viscosity of the resin composition is the same as that obtained by adding spherical silica powder that has been surface-treated in the same manner. A resin having a high adhesive strength was obtained.

  Table 1 shows the reaction conditions of Examples 1 to 18 and Comparative Examples 1 to 3. Table 2 shows the measurement results of various physical properties in Examples 1 to 18 and Comparative Examples 1 to 3.

  The present invention can be suitably used, for example, in the field of semiconductor encapsulant fillers and the like.

  1 Deformed silica particles

Claims (10)

The median diameter of the weight-based particle size distribution measured by centrifugal sedimentation is in the range of 50-1000 nm,
The ratio (S / S ₀ ) between the area (S) obtained by the image analysis method and the envelope area (S ₀ ) obtained by the image analysis method is in the range of 0.60 to 0.95,
There is one maximum (peak) of the weight-based particle size distribution obtained by the centrifugal sedimentation method, and the geometric standard deviation σg is 1.5 or less,
A deformed silica powder having a saturated water content of 1.5% by mass or less as measured by a loss on drying method at 120 ° C.   The deformed silica powder according to claim 1, wherein the average circularity of particles obtained by an image analysis method is in the range of 0.40 to 0.85.   The deformed silica powder according to claim 1 or 2, wherein the content of particles having a circularity of 0.95 or more obtained by an image analysis method is 5% by number or less.   The deformed silica powder according to any one of claims 1 to 3, wherein the contents of sodium, potassium and iron are each less than 1 ppm.   The deformed silica powder according to any one of claims 1 to 4, which has hydrophobicity.   The resin composition containing the unusual shape silica powder of any one of Claims 1-5.   An alkoxysilane or a hydrolyzate thereof and / or a partial condensate thereof is added to the fumed silica dispersion and a polycondensation reaction is performed to obtain a reaction liquid in which the irregular silica particles are suspended, and the irregular silica particles are obtained from the obtained reaction liquid. A method for producing deformed silica powder, comprising: a step of recovering the recovered silica; a step of firing the recovered deformed silica particles; and a step of crushing the silica particles obtained from the firing step.   Furthermore, the manufacturing method of the irregular shaped silica powder of Claim 7 including the process of hydrophobizing the surface of the obtained silica particle. A core-shell type deformed silica powder composed of a core part and a shell part covering the core part,
The core part is made of fumed silica,
The shell part is a silica layer obtained by a sol-gel method,
A deformed silica powder having a saturated water content of 1.5% by mass or less as measured by a loss on drying method at 120 ° C.   The deformed silica powder according to claim 9, wherein the surface of the shell part is surface-treated.

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