JP2007039304A - Filler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filler having excellent fluidity and dispersibility into a base material. <P>SOLUTION: The filler contains a ceramic particle possessing following requirements (I)-(III). (I) The total quantity of Al<SB>2</SB>O<SB>3</SB>or MgO and SiO<SB>2</SB>is ≥80 wt.%. (II) The ratio [(Al<SB>2</SB>O<SB>3</SB>or MgO)/(SiO<SB>2</SB>)] by weight of Al<SB>2</SB>O<SB>3</SB>or MgO to SiO<SB>2</SB>is 0.1-15. (III) The average particle diameter, sphericity and water absorption coefficient are respectively 0.01-50 μm, ≥0.95 and ≤0.8 wt.%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a filler containing specific ceramic particles.

  The filler is added to a base material such as plastic, rubber, paint, fiber, paper, glass, metal, and improves the physical properties of the base material and contributes to the improvement of workability and the function of the final product.

  Ceramic particles have stable physicochemical properties, and various studies have been made on the main component of fillers. The ceramic particles used in the filler composition are preferably spherical from the viewpoint of improving fluidity, which is a basic physical property of the filler. Patent Document 1 discloses ceramics by a firing method mainly containing alumina.

JP 2003-192339 A

  However, spherical ceramics based on a firing method mainly composed of silica or alumina have insufficient fluidity, so that dispersibility to a substrate is poor and filling properties are not sufficient.

  An object of the present invention is to provide a filler containing ceramic particles having excellent fluidity and having excellent filling properties when added to a substrate.

As a means for solving the problems, the present invention provides a filler according to a first aspect, which is a filler containing ceramic particles, and the ceramic particles satisfy the following requirements (I) to (III).
(I) The total amount of Al ₂ O ₃ or MgO and SiO ₂ is 80% by weight or more.
(II) The weight ratio of Al ₂ O ₃ or MgO to SiO ₂ [(Al ₂ O ₃ or MgO) / SiO ₂ ] is 0.1 to 15.
(III) Average particle diameter, sphericity and water absorption are 0.01 to 50 μm, 0.95 or more and 0.8% by weight or less, respectively.

The present invention provides, as means for solving the problems, a filler containing ceramic particles, wherein the ceramic particles satisfy the following requirements (I) to (IV).
(I) The total amount of Al ₂ O ₃ or MgO and SiO ₂ is 80% by weight or more.
(II) The weight ratio of Al ₂ O ₃ or MgO to SiO ₂ [(Al ₂ O ₃ or MgO) / SiO ₂ ] is 0.1 to 15.
(III) The average particle size is 0.01 to 50 μm.
(IV) Manufactured by flame melting method.

As a means for solving the problems, the present invention is a filler containing ceramic particles, wherein the ceramic particles melt powder particles satisfying the following requirements (I), (V) and (VI) in a flame: The filler which is a thing of the 3rd aspect which can be obtained is provided.
(I) The total amount of Al ₂ O ₃ or MgO and SiO ₂ is 80% by weight or more.
(V) and _Al 2 _{O 3} or MgO, the weight ratio of SiO _{2 [(Al} 2 _{O 3} or MgO) / SiO _2] is 0.1 to 17.
(VI) The average particle size is 0.01 to 50 μm.

  In the present invention, the filler is added to and used in a base material such as powder or liquid, and the solvent or molten state of the base material is dissolved regardless of the manufacturing temperature of the base material containing the filler. Particles in all forms that are insoluble in the substrate itself.

  ADVANTAGE OF THE INVENTION According to this invention, the fluidity | liquidity is favorable, the dispersibility when it adds to a base material is favorable, and the filler which can improve the filling property to a base material can be provided.

  The inventors of the present invention have completed the present invention by paying attention to the fact that ceramic particles satisfying a specific particle size and the like with a specific composition, in particular, the ceramic particles obtained by a flame melting method are excellent as a raw material for fillers. It came to do.

<Ceramic particles>
(1) First Embodiment In the first embodiment, the ceramic particles have the following requirements (I) to (III).
(I) The total amount of Al ₂ O ₃ or MgO and SiO ₂ is 80% by weight or more.
(II) The weight ratio of Al ₂ O ₃ or MgO to SiO ₂ [(Al ₂ O ₃ or MgO) / SiO ₂ ] is 0.1 to 15.
(III) Average particle diameter, sphericity and water absorption are 0.01 to 50 μm, 0.95 or more and 0.8% by weight or less, respectively.

[Requirement (I)]
In the requirement (I), Al ₂ O ₃ or MgO can be included in the component, but MgO is preferable from the viewpoint of ensuring impact resistance and making the specific gravity of the filler appropriate.

Furthermore, in the requirement (I), from the same viewpoint, the content ratio of Al ₂ O ₃ and SiO ₂ or the content ratio of MgO and SiO ₂ is 80% by weight or more, preferably 85% by weight or more, more preferably Is 90% by weight or more, particularly preferably 100% by weight.

[Requirement (II)]
In requirement (II), the weight ratio of Al ₂ O ₃ / SiO ₂ or the weight ratio of MgO / SiO ₂ is 0.1 to 15, preferably 0.2 to 12, more preferably 0. 3-9.
When the filler of the present invention satisfies the above requirements (I) and (II), when it is added to a base material such as plastic, it has more favorable mechanical properties (such as bending and pulling) than the case of only the base material. Mechanical strength, impact resistance, abrasion resistance, etc.), chemical properties (chemical resistance, light resistance, flame resistance, etc.), physical properties (electrical insulation, low dielectric properties, thermal conductivity, etc.) And the substrate can be modified.

[Requirement (III)]
In requirement (III), the average particle size of the ceramic particles is 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less, from the viewpoint of ensuring the mechanical strength of the substrate when the filler is added to the substrate. . Further, from the viewpoint of suppressing the aggregation and coalescence of fine particles and not increasing the particle size distribution width of the ceramic particles or from the viewpoint of sphericity, it is preferably 0.01 μm or more, more preferably 0.1 μm or more, and 4 μm or more. Is more preferable, and 10 μm or more is more preferable.

  The average particle diameter means D50 (volume basis), and is measured by a laser diffraction / scattering method by Horiba LA-920.

In requirement (III), the sphericity of the ceramic particles is 0.95 or more, preferably 0.96 or more, more preferably 0.98 or more, from the viewpoint of improving fluidity. When the sphericity is within this range, the dispersibility to the base material is good, high addition becomes possible, and the properties of the filler (for example, thermal conductivity, flame retardancy, etc.) are easily imparted to the base material. Moreover, when adding as a plastic filler, it is preferable at the point that abrasion of the metal mold | die at the time of shaping | molding is suppressed, or a contamination reduces.
Furthermore, since the fluidity is improved, the dispersibility to the base material to which the filler is added can be improved. As a result, the filler characteristics can be reflected on the base material with a small amount of addition, and the base material can be modified. Quality becomes easy. Further, when the base material is, for example, a low-viscosity liquid resin, the viscosity increase due to the addition of filler can be suppressed, and the base material can be modified while maintaining the fluidity of the base material. In addition, when a filler having a high sphericity is added to plastic or the like, antiblocking properties, scratch resistance, and slidability can be imparted. Further, by blending in a large amount, high-density filling into the base material becomes possible, and dimensional stability at the time of molding the base material to which the filler is added can be secured.

  The sphericity is obtained by image-analyzing a photographic image of ceramic particles with a scanning electron microscope to determine the area of the particle projection cross section of the particle and the perimeter of the cross section. The circumference of the perfect circle] / [perimeter of the particle projection cross section] is calculated, and the obtained values are averaged for any 50 particles.

  Ceramic particles used in the present invention from the viewpoint of not impairing the physical properties of the base material, and particularly from the viewpoint of suppressing the formation of bubbles in the product after melt-kneading and the like when added as a filler of a plastic base material The surface is required to have few pores. As the degree of pores on the surface, the water absorption rate of ceramic particles can be used as an index. That is, the pores of the ceramic particles tend to be smaller when the water absorption is lower, and in the requirement (III), the water absorption needs to be 0.8% by weight or less, preferably 0.5% by weight or less, More preferably, it is 0.3% by weight or less. The water absorption rate can be measured according to the water absorption rate measuring method of JIS A1109 fine aggregate.

(2) Second Embodiment In the second embodiment, the ceramic particles have the following requirements (I) to (IV). Requirements (I) and (II) are the same as those in the first embodiment.
(I) The total amount of Al ₂ O ₃ or MgO and SiO ₂ is 80% by weight or more.
(II) The weight ratio of Al ₂ O ₃ or MgO to SiO ₂ [(Al ₂ O ₃ or MgO) / SiO ₂ ] is 0.1 to 15.
(III) The average particle size is 0.01 to 50 μm.
(IV) Manufactured by flame melting method.

The average particle diameter of the ceramic particles of requirement (III) is 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less, from the viewpoint of ensuring the mechanical strength of the substrate when the filler is added to the substrate. Further, from the viewpoint of suppressing the aggregation and coalescence of fine particles and not increasing the particle size distribution width of the ceramic particles or from the viewpoint of sphericity, it is preferably 0.01 μm or more, more preferably 0.1 μm or more, and 4 μm or more. Is more preferable, and 10 μm or more is more preferable. The method for measuring the average particle size is as described above.
Furthermore, since the fluidity is improved, the dispersibility to the base material to which the filler is added can be improved. As a result, the filler characteristics can be reflected on the base material with a small amount of addition, and the base material can be modified. Quality becomes easy. Further, when the base material is, for example, a low-viscosity liquid resin, the viscosity increase due to the addition of filler can be suppressed, and the base material can be modified while maintaining the fluidity of the base material. Further, when a filler having a high sphericity is added to plastic or the like, anti-blocking properties, scratch resistance, and slidability can be imparted. Further, by blending in a large amount, high-density filling into the base material becomes possible, and dimensional stability at the time of molding the base material to which the filler is added can be secured.

(3) Third Embodiment In the third embodiment, ceramic particles can be obtained by melting powder particles having the following requirements (I), (V), and (VI) in a flame. Is. The requirement (I) is the same as that in the first embodiment.
(I) The total amount of Al ₂ O ₃ or MgO and SiO ₂ is 80% by weight or more.
(V) and _Al 2 _{O 3} or MgO, the weight ratio of SiO _{2 [(Al} 2 _{O 3} or MgO) / SiO _2] is 0.1 to 17.
(VI) The average particle size is 0.01 to 50 μm.

In the requirement (V), the weight ratio of Al ₂ O ₃ or MgO / SiO ₂ is 0.1 to 17, preferably 0.2 to 15, and more preferably 0.3 to 12.

  In requirement (VI), the upper limit of the average particle diameter of the powder particles is preferably 50 μm or less, more preferably 40 μm or less, further preferably 30 μm or less, and particularly preferably 20 μm or less. Further, from the viewpoint of suppressing aggregation and coalescence of fine particles and not increasing the width of the particle size distribution of the powder particles and the viewpoint of sphericity, the lower limit is preferably 0.01 μm or more, more preferably 0.1 μm or more. 5 μm or more is more preferable, and 10 μm or more is more preferable.

<Method for producing ceramic particles>
The ceramic particles used in the present invention are preferably manufactured by applying the flame melting method in the first and third embodiments, and manufactured by applying the flame melting method in the second embodiment.

(1) Composition of raw material powder particles Al ₂ O ₃ or MgO and SiO ₂ are contained at 80% by weight or more, Al ₂ O ₃ or MgO / SiO ₂ weight ratio is 0.1 to 17, and average particle size is 50 μm or less. These powder particles are used as starting materials. MgO is preferable.
The content ratio of Al ₂ O ₃ or MgO and SiO ₂ in the powder particles is preferably 85% by weight or more, more preferably 90% by weight or more, particularly preferably 100% by weight, and Al ₂ O ₃ or MgO / SiO 2 The weight ratio of ₂ is 0.1-17, preferably 0.2-15, more preferably 0.3-12, and the degree of distribution of the unfused particle size is low (the particle size range is narrow). From the viewpoint of obtaining spherical particles, it is more preferably 1.5 to 10. In order to obtain the desired ceramic particles, the powder particles as the starting material are used by adjusting the weight ratio of Al ₂ O ₃ or MgO / SiO ₂ within the above range in consideration of component evaporation during melting. It is preferable to do.

(2) Average particle diameter and shape of raw material powder particles The upper limit of the average particle diameter of the raw material powder particles is preferably 50 µm or less, more preferably 40 µm or less, further preferably 30 µm or less, and further preferably 20 µm or less. Further, from the viewpoint of suppressing the particle size and the sphericity from becoming too wide, the lower limit is preferably 0.01 μm or more, more preferably 0.1 μm or more, further preferably 5 μm or more, and further preferably 10 μm or more.

  In addition, it is preferable to select the shape of the raw material powder particles from the viewpoint of promptly spheroidizing in a flame and obtaining ceramic particles having a high sphericity and not having a very wide particle size distribution. As the shape, it is preferable that the ratio of the major axis diameter / minor axis diameter of the raw material powder particles is 9 or less, more preferably 4 or less, from the viewpoint of ensuring residence time in the flame, melting, and quickly spheroidizing. More preferably, it is 2 or less.

(3) Moisture content of raw material powder particles When the powder particles that are the starting material are melted, if the particles contain water, the water will evaporate. A hole may be formed. Therefore, the water content (% by weight) of the starting material is preferably 10% by weight or less, more preferably 3% by weight or less, more preferably 1% by weight from the viewpoint of adjusting the water absorption and sphericity of the obtained particles to an appropriate range. More preferred are: The water content is determined by measuring the weight loss when 1 g of powder particles is heated at 800 ° C. for 1 hour, and calculated from the following formula: (weight before heating−weight after heating) / weight before heating × 100.

(4) Example of raw material powder particles (in the case of Al ₂ O ₃ )
Examples of the raw material as the A1 ₂ O ₃ source include bauxite, van earth shale, aluminum oxide, aluminum hydroxide, boehmite, aluminum sulfate, aluminum nitrate, aluminum chloride, alumina sol, aluminum alkoxide such as aluminum isopropoxide, and the like. .
Examples of the raw material as the SiO ₂ source include silica, silica sand, quartz, cristobalite, amorphous silica, feldspar, pyrophyllite, fumed silica, ethyl silicate, silica gel, and the like.
Examples of the raw material as a source of (A1 ₂ O ₃ + SiO ₂ ) include kaolin, van earth shale, bauxite, mica, sillimanite, andalusite, mullite, zeolite, montmorillonite, and hyrosite.
These raw materials can be used alone or in admixture of two or more. The selected starting material is preferably used after calcining in order to reduce its moisture content or to facilitate its melting. Examples of the calcined raw material powder particles include calcined van pages, calcined mullite, calcined bauxite, a mixture of calcined aluminum hydroxide and kaolin, and the like.

(In the case of MgO)
Examples of the raw material as the MgO source include magnesium carbonate, magnesium oxide, magnesium hydroxide, olivine, pyroxene dunstone, serpentine, and olivine minerals.
Further, mention may be made as a raw material of a (MgO + SiO ₂₎ source, forsterite, clino enstatite, enstatite, olivine, pyroxene, Dung rock, serpentine, basalt, olivine-based minerals, talc and the like.
These raw materials can be used alone or in admixture of two or more. The selected starting material is preferably used after calcining in order to reduce its moisture content or to facilitate its melting. Examples of the calcined raw material powder particles include calcined serpentine, calcined olivine, calcined pyroxene, calcined dunstone forsterite, calcined enstatite, and the like.

(5) Spheronization by flame melting method In the spheronization process of raw material powder particles, a flame melting method is applied in which the raw material powder particles are dispersed in a carrier gas such as oxygen and melted by being put into a flame, and then spheroidized. To do.
The flame is generated by burning fuel such as propane, butane, methane, natural liquefied gas, LPG, heavy oil, kerosene, light oil, and pulverized coal with oxygen. Further, a plasma jet flame generated by ionizing N ₂ inert gas or the like may be used.
The volume ratio of the fuel to oxygen is preferably 1.01 to 1.3 from the viewpoint of complete combustion. From the viewpoint of generating a high-temperature flame, it is preferable to use an oxygen / gas burner. Although the structure of the burner is not particularly limited, the burners disclosed in JP-A-7-48118, JP-A-11-132421, JP-A-2000-205523, or JP-A-2000-346318 are disclosed. preferable.

  The flame temperature is preferably equal to or higher than the melting point of the raw material powder particles from the viewpoint of melting and spheronizing the raw material powder particles. Specifically, 1700 ° C. or higher is preferable, 2000 ° C. or higher is more preferable, and 2600 ° C. or higher is further preferable.

The powder particles are preferably introduced into the flame by being dispersed in a carrier gas. As the carrier gas, oxygen is preferably used. In this case, there is an advantage that oxygen of the carrier gas can be consumed for fuel combustion. The concentration of the powder in the gas is preferably 0.1 to 20 kg / Nm ^{3 and} more preferably 0.2 to 10 kg / Nm ³ from the viewpoint of ensuring sufficient dispersibility of the powder particles. Furthermore, when thrown into the flame, it is more preferable to pass through a mesh, a static mixer or the like to improve dispersibility.

  By such a method, ceramic particles used in the present invention can be obtained. In addition, from the viewpoint of improving the dispersibility of the filler in the base material, the ceramic particles may be surface-treated with silicone, soap or the like in addition to the surface treatment with a silane coupling agent or the like.

Ceramic particles used for the filler of the present invention (hereinafter also referred to as “ceramic particles of the present invention”) are a composite compound containing Al ₂ O ₃ or MgO and SiO ₂ . The structure can be an amorphous structure (amorphous) or a crystalline structure (crystalline), but a crystalline one is preferred from the viewpoint of developing good physical properties as a filler. In the case where the ceramic particles are crystalline, the main peak by the X-ray diffraction pattern measurement is JCPDS (Joint Committee on Powder Diffraction Standards) No. It is preferable to belong to a peak attributed to Mullite of 15-776, a peak attributed to Forsterite of JCPDS No. 34-189, or a Clinoenstatite of JCPDS No. 35-610.

<Filler>
The filler of the present invention may be composed only of the ceramic particles of the present invention, or may be composed of the ceramic particles of the present invention and other components.

  In order to solve the problems of the present invention, the filler of the present invention preferably contains 20% by weight or more, more preferably 40% by weight or more, still more preferably 60% by weight or more, in the filler. Particularly preferred is 100% by weight.

  Components other than the ceramic particles of the present invention can be selected depending on the application within a range not impairing the solution of the problems of the present invention.

  The average particle diameter, sphericity, and water absorption rate of the other filler particles are preferably set to the same level as the requirement (III), for example.

The filler of the present invention preferably has the following characteristics.
(1) Fluidity Since the ceramic particles of the present invention have high sphericity and smoothness (there are few pores and low water absorption), the fluidity of the filler can be improved. For the fluidity, the angle of repose measured by a powder tester is used as an index. When the filler is composed of the ceramic particles of the present invention, the angle of repose of the filler is preferably 55 degrees or less, more preferably 50 degrees or less. The angle of repose is measured according to JIS R9301-2-2. As a powder tester used for measuring the angle of repose, TYPE PT-E manufactured by Hosokawa Micron Corporation is used.

(2) Specific gravity From the viewpoint of expressing the physical action of the filler in the substrate with a small addition amount, the specific gravity of the filler is preferably 4 or less, more preferably 3.8 or less, when the filler is composed of the ceramic particles of the present invention. More preferably, it can be 3.5 or less.

(3) Color The filler of the present invention is preferably white from the viewpoint of physical properties (particularly optical properties). When the ceramic particles of the present invention constitute a filler, the whiteness of the filler is, for example, such that the L * value measured by a spectroscopic colorimeter is preferably 85 or more, more preferably 90 or more, and still more preferably 95 or more. Can do. The color of the powder becomes whiter as the particle size is smaller, and the whiteness can be achieved by satisfying the requirement (III) of the present invention.
Increasing the whiteness of the filler of the present invention improves the transparency of the filler of the present invention, so when added to a substrate such as plastic, paint, fiber, paper, etc., the effect on the color and transparency of the substrate The substrate can be modified while suppressing the above. Furthermore, the optical characteristics of the filler can be easily imparted, and the optical characteristics of the substrate can be easily modified.

  The filler of the present invention is suitably used as an additive for glass, plastic (thermoplastic resin and thermosetting resin), elastomer, paint, rubber, adhesive, metal, fiber, paper, etc., and particularly suitable for plastic applications. It is.

  The blending amount of the filler of the present invention is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, and further preferably 10 parts by weight with respect to 100 parts by weight of the base material, from the viewpoint of the manifestation of filler properties. From the viewpoint of filling into the substrate, it is preferably 1000 parts by weight or less, more preferably 800 parts by weight or less, and still more preferably 500 parts by weight or less.

Example 1
(1) Raw material powder particles Commercial synthetic mullite powder 1 shown in Table 1 was used.
(2) Spheroidization method (flame melting method)
The raw material powder particles were charged into a flame (2000 ° C.) in which oxygen was used as a carrier gas and LPG (propane gas) was burned at an oxygen ratio (volume ratio) of 1.1 to obtain ceramic particles 1. The properties of the filler composed of 100% by weight of the obtained ceramic particles 1 were as shown in Table 2. A scanning electron micrograph of ceramic particles 1 (manufactured by Keyence Corporation, real surface view microscope VE-7800, magnification: 500 times) is shown in FIG.

Example 2
(1) Raw Material Powder Particles Commercial synthetic forsterite powder shown in Table 1 was used as raw material powder particles.
(2) Spheronization method Ceramic particles 2 were obtained in the same manner as in Example 1. However, the flame temperature was 2000 ° C. Properties of the filler composed of 100% by weight of the obtained ceramic particles 2 are as shown in Table 2.

Example 3
(1) Raw material powder particles The raw material powder particles shown in Table 1 were used.
(2) Spheronization method Ceramic particles 3 were obtained in the same manner as in Example 1. Properties of the filler composed of 100% by weight of the obtained ceramic particles 3 are as shown in Table 2.

Example 4
(1) Raw material powder particles The raw material powder particles shown in Table 1 were used.
(2) Spheroidization Method Ceramic particles 4 were obtained in the same manner as in Example 2. Properties of the filler composed of 100% by weight of the obtained ceramic particles 4 are as shown in Table 2.

Example 5
(1) Raw material powder particles The raw material powder particles shown in Table 1 were used. _However, Al ₂ 0 3 / SiO ₂ weight ratio of 2.5 and composed as 700 ° C. in an electric furnace a mixture of aluminum hydroxide and kaolin, and 1 hour calcination, as a raw material powder particles.
(2) Spheronization method Ceramic particles 5 were obtained in the same manner as in Example 1. Properties of the filler composed of 100% by weight of the obtained ceramic particles 5 are as shown in Table 2.

Example 6
(1) Raw material powder particles The raw material powder particles shown in Table 1 were used. However, a mixture of magnesium hydroxide and silica so that the weight ratio of MgO and SiO ₂ was 1.5 was calcined in an electric furnace at 900 ° C. for 1 hour to obtain raw material powder particles.
(2) Spheronization method Ceramic particles 6 were obtained in the same manner as in Example 2. Properties of the filler composed of 100% by weight of the obtained ceramic particles 6 are as shown in Table 2.

Comparative Examples 1 and 2
Commercial powder particles shown in Table 2 were used.

Comparative Example 3
A mixture of aluminum hydroxide and kaolin so as to have an Al ₂ O ₃ / SiO ₂ weight ratio of 2.8 shown in Table 1 was baked in an electric furnace at 1500 ° C. for 1 hour to obtain comparative ceramic particles 1. Table 2 shows the properties of the filler composed of 100% by weight of the comparative ceramic particles 1 obtained. A scanning electron micrograph of the comparative ceramic particles 1 (manufactured by Keyence Corporation, real surface view microscope VE-7800, magnification: 500 times) is shown in FIG.

  As is clear from Table 2, the fillers of Examples 1 to 6 had predetermined requirements for the ceramic particles of the present invention, and therefore had an angle of repose of less than 50 degrees and high fluidity. For this reason, when mix | blending as a filler of a plastic base material, for example, the dispersibility to a base material is good and the workability of a base material is also improved.

  On the other hand, since the sphericity of the powders of Comparative Examples 1 to 3 is outside the range of the present invention, the angle of repose is high, the fluidity is inferior, and the dispersibility to the substrate is also poor. In addition, since the ceramic particles of Comparative Example 3 have a high water absorption rate, for example, when blended as a filler for a plastic substrate, it is considered that bubbles are contained in the product after melt-kneading to reduce mechanical strength. It is done.

  As is clear from FIGS. 1 and 2, the ceramic particles of Example 1 were spherical, whereas the ceramic particles of Comparative Example 3 were indefinite. Such a difference in shape is considered to have a great influence on the fluidity.

2 is a scanning electron micrograph of ceramic particles 1. 2 is a scanning electron micrograph of comparative ceramic particles 1.

Claims (3)

A filler containing ceramic particles, wherein the ceramic particles satisfy the following requirements (I) to (III).
(I) The total amount of Al ₂ O ₃ or MgO and SiO ₂ is 80% by weight or more.
(II) The weight ratio of Al ₂ O ₃ or MgO to SiO ₂ [(Al ₂ O ₃ or MgO) / SiO ₂ ] is 0.1 to 15.
(III) Average particle diameter, sphericity and water absorption are 0.01 to 50 μm, 0.95 or more and 0.8% by weight or less, respectively. A filler containing ceramic particles, wherein the ceramic particles satisfy the following requirements (I) to (IV).
(I) The total amount of Al ₂ O ₃ or MgO and SiO ₂ is 80% by weight or more.
(II) The weight ratio of Al ₂ O ₃ or MgO to SiO ₂ [(Al ₂ O ₃ or MgO) / SiO ₂ ] is 0.1 to 15.
(III) The average particle size is 0.01 to 50 μm.
(IV) Manufactured by flame melting method. A filler containing ceramic particles, wherein the ceramic particles can be obtained by melting powder particles satisfying the following requirements (I), (V) and (VI) in a flame.
(I) The total amount of Al ₂ O ₃ or MgO and SiO ₂ is 80% by weight or more.
(V) Weight ratio of Al ₂ O ₃ or MgO and SiO ₂ [(Al ₂ O ₃ or MgO) / S
iO _2] is 0.1 to 17.
(VI) The average particle size is 0.01 to 50 μm.