JP2022144115A - Inorganic oxide fine hollow particles - Google Patents

Abstract

To provide inorganic oxide fine hollow particles which have a uniform particle size and are excellent in particle strength and are less likely to be peeled off when the coating film is formed.SOLUTION: There is provided inorganic oxide fine hollow particles having a shell defining a hollow space. A content of an alkali metal oxide is 2 mass% or less, and a content of the calcium oxide is 5 mass% or less, and a total content of silicon oxide, boron oxide and aluminum oxide is 50 mass% or more. A particle size distribution is unimodal, and a particle size gradient calculated by the following formula (1) is 2 or less. Particle size gradient=(D90-D10)/D50...(1), wherein D90 represents a cumulative 90% particle diameter in a volume-based particle size distribution, D10 represents a cumulative 10% particle diameter in a volume-based particle size distribution, and D50 represents a cumulative 50% particle diameter in a volume-based particle size distribution.SELECTED DRAWING: Figure 1

Description

The present invention relates to inorganic oxide fine hollow particles.

Inorganic oxide hollow particles have cavities surrounded by an outer shell, so compared to solid particles, they are lighter, have lower thermal conductivity, and are superior in thermal stability. It is widely used as a carrier, building material, electronic material, and the like. In recent years, electronic devices are rapidly becoming more sophisticated and smaller, and there is a high demand for thinner coatings, resin products, and film products used in electronic devices. are required to be fine and uniform in particle size.

Conventionally, micro hollow glass spheres having an average particle diameter of 5 to 50 μm and particles of 5 to 50 μm occupying 80% or more of the whole are known as inorganic oxide hollow particles having a uniform particle size. (Patent Document 1). In addition, the average particle size (by volume) is 15 μm or less, the maximum particle size is 45 μm or less, the particle density is 0.5 g/cm ³ or less, and (d ₁₀ −d ₉₀ )/d ₅₀ is calculated. There is also a report of micro hollow glass spheres having a particle size gradient of 2.0 or less and a B ₂ O ₃ content of 9.0 to 20.0% by mass in the glass (Patent Document 2).

JP-A-9-20526 WO 2001/2314

However, in the inorganic oxide hollow particles of Patent Document 1, about 80% of the particles have an average particle diameter of 5 to 50 μm, so there is room for improvement in terms of uniformity of particle size. In addition, if the uniformity of the particle size is low, there is also a problem that when the coating film is formed by mixing with the binder, it is easily peeled off from the substrate. On the other hand, the inorganic oxide hollow particles of Patent Document 2 have a large maximum particle size of 15 μm and a yield of 30 to 45% by mass, despite the fact that only water suspended matter is sorted out in the manufacturing process. and low. The reason for this is presumed to be clogging due to the tendency of fine particles to agglomerate during the classification operation, and the fact that the agglomerates were broken due to their low strength when crushed. In this case, it is conceivable to increase the particle strength by increasing the film thickness of the inorganic oxide hollow particles. is inevitable.
An object of the present invention is to provide fine hollow particles of inorganic oxide which have a uniform particle size, are excellent in particle strength, and are difficult to peel off when a coating film is formed.

As a result of investigation in view of the above problems, the present inventors have found that hollow particles having a small particle size containing a specific inorganic oxide in a specific ratio, having a unimodal particle size distribution, and based on a specific particle size It has been found that hollow particles having a small particle size gradient calculated by the method have excellent particle strength and are difficult to peel off when a coating film is formed.

That is, the present invention provides the following [1] to [8].
[1] An inorganic oxide fine hollow particle having a shell defining a hollow chamber,
The content of the alkali metal oxide is 2% by mass or less,
The content of calcium oxide is 5% by mass or less,
The total content of silicon oxide, boron oxide and aluminum oxide is 50% by mass or more,
The particle size distribution is unimodal, and the following formula (1);
Particle size gradient = (D ₉₀ - D ₁₀ )/D ₅₀ (1)
[In the formula, D ₉₀ represents the cumulative 90% particle size in the volume-based particle size distribution, D ₁₀ represents the cumulative 10% particle size in the volume-based particle size distribution, and D ₅₀ represents the cumulative 50% in the volume-based particle size distribution. Particle size is indicated. ]
The particle size gradient calculated by is 2 or less,
Inorganic oxide micro hollow particles.
[2] The inorganic oxide fine hollow particles according to [1] above, which have a D ₁₀₀ of 15 μm or less.
[3] The inorganic oxide fine hollow particles according to [1] or [2], which have a D ₅₀ of 0.5 to 5 μm.
[4] The inorganic oxide fine hollow particles according to any one of [1] to [3], wherein the silicon oxide content is 20 to 70% by mass.
[5] The inorganic oxide fine hollow particles according to any one of [1] to [4], wherein the boron oxide content is 15 to 35% by mass.
[6] The inorganic oxide fine hollow particles according to any one of [1] to [5], wherein the aluminum oxide content is 5 to 20% by mass.
[7] For a test piece with a copper plate prepared by the following method, when measured in accordance with JIS K 6854-1, the 90-degree peel adhesion strength of the resin layer from the copper plate is more than 10 N / m. The inorganic oxide fine hollow particles according to any one of [1] to [6].
[Preparation of test piece with copper plate]
5 g of dry powder of inorganic oxide fine hollow particles, 30 g of a mixture of liquid bisphenol A type epoxy resin and liquid bisphenol F type epoxy resin (average epoxy equivalent: 165 g/mol), 20 g of liquid phenol novolac (hydroxy group equivalent: 135 g/mol), and 1 g of triphenylphosphine is added to the mixed epoxy resin liquid and mixed. The resin mixture is coated on a flexible adherend bent at right angles with a width of 25 mm, a length of 150 mm, and a thickness of 1 mm. and glue. Then, it is dried and cured in a dryer at 80° C. for 12 hours to prepare a test piece.
[8] A resin composition comprising the inorganic oxide fine hollow particles according to any one of [1] to [7].

According to the present invention, it is possible to provide inorganic oxide hollow particles that not only have a small particle size and a uniform particle size, but also have excellent particle strength and are difficult to peel off when a coating film is formed. Therefore, the inorganic oxide fine hollow particles of the present invention are useful for various applications such as electronic materials such as wiring circuit boards and semiconductor sealing materials, heat insulating materials, heat shielding materials, catalyst carriers, building materials and the like.

4 is a diagram showing the particle size distribution of inorganic oxide hollow particles obtained in Example 4 and Comparative Example 1. FIG.

As used herein, the term “hollow particle” refers to a particle having a hollow structure inside and having an outer shell portion that partitions the hollow portion. different from particles. The hollow particles can be clearly distinguished from the porous particles by scanning electron microscope (SEM) images.

The inorganic oxide hollow particles of the present invention have outer shells made of inorganic oxides containing alkali metal oxides, calcium oxides, silicon oxides, boron oxides and aluminum oxides. By forming the outer shell portion from such an inorganic oxide, hollow particles having a small particle size, a uniform particle size, excellent particle strength, and being difficult to peel off when a coating film is formed can be obtained. From this point of view, the outer shell is preferably non-porous. In addition, it can be confirmed by a scanning electron microscope (SEM) image or by floating on water that the particle surface is non-porous.
In this specification, each content of the inorganic oxides constituting the hollow particles is a value obtained by measuring the content in terms of oxide by fluorescent X-ray spectroscopy and calculating the chemical component.

Examples of alkali metal oxides include _Li2O , _Na2O , _K2O , _Rb2O and _Cs2O . Among them, one or two or more selected from Li ₂ O, Na ₂ O and K ₂ O are preferable from the viewpoint of miniaturization, uniformity of particle size, improvement of particle strength and peel strength of the coating film, and Na ₂ O is More preferred.
As the calcium oxide, CaO is preferable from the viewpoint of miniaturization, uniformity of particle size, improvement of particle strength and peel strength of the coating film.
As the silicon oxide, SiO ₂ is preferable from the viewpoints of miniaturization, uniformity of particle size, improvement of particle strength and peel strength of the coating film.
As the boron oxide, B ₂ O ₃ is preferable from the viewpoints of miniaturization, uniformity of particle size, improvement of particle strength and peel strength of the coating film.
As the aluminum oxide, Al ₂ O ₃ is preferable from the viewpoints of miniaturization, uniformity of particle size, improvement of particle strength and peel strength of the coating film.

The content of the alkali metal oxide is 2% by mass or less, but from the viewpoint of miniaturization, uniformity of particle size, improvement of particle strength and peel strength of the coating film, it is preferably 1.8% by mass or less, and 1.5% by mass. % by mass or less is more preferable, and 1.3% by mass or less is even more preferable. The lower limit of the content of the alkali metal oxide may be 0% by mass, but from the viewpoint of lowering the firing temperature due to the lowering of the melting point of the inorganic oxide, it is preferably 0.1% by mass or more, and 0.2% by mass. % by mass or more is more preferable, and 0.3% by mass or more is even more preferable.
The content of calcium oxide is preferably 5% by mass or less from the viewpoint of miniaturization, uniformity of particle size, improvement of particle strength and peel strength of the coating film. Although the lower limit of the content of calcium oxide may be 0% by mass, it is preferably 0.5% by mass or more, and 1.0% by mass, from the viewpoint of lowering the firing temperature due to the lowering of the melting point of the inorganic oxide. % or more is more preferable, and 1.5% by mass or more is even more preferable.

The total content of silicon oxides, boron oxides and aluminum oxides is 50% by mass or more. % by mass or more is preferable, 65% by mass or more is more preferable, and 70% by mass or more is even more preferable. The upper limit of the total content is preferably 93% by mass or less from the viewpoint of lowering the firing temperature due to the lowering of the melting point of the inorganic oxides.

Silicon oxide, boron oxide and aluminum oxide may contain one or more of these three types, but containing all three types is effective for miniaturization, uniformity of particle size, particle strength and coating film It is preferable from the viewpoint of improving the peel strength of.
The content of silicon oxide is preferably 20 to 70% by mass, more preferably 25 to 65% by mass, more preferably 30 to 60%, from the viewpoint of miniaturization, uniformity of particle size, improvement of particle strength and peel strength of the coating film. % by weight is more preferred, and 40 to 55% by weight is even more preferred.
The content of boron oxide is preferably 15 to 35% by mass, more preferably 16 to 34% by mass, more preferably 17 to 33, from the viewpoint of miniaturization, uniformity of particle size, improvement of particle strength and peel strength of the coating film. % by weight is more preferred, and 18 to 32% by weight is even more preferred.
The content of aluminum oxide is preferably 5 to 20% by mass, more preferably 5 to 19% by mass, more preferably 5 to 18% by mass, from the viewpoint of miniaturization, uniformity of particle size, improvement of particle strength and peel strength of the coating film. % by mass is more preferred.

Above all, controlling the content of calcium oxide contributes most to miniaturization, uniformity of particle size, improvement of particle strength and peel strength of the coating film.

The inorganic oxide hollow particles of the present invention may contain inorganic oxides other than those mentioned above as inorganic oxides constituting the outer shell portion. For example, Group 2 element oxides and Group 4 element oxides other than calcium oxides can be mentioned.
Group 2 element oxides other than calcium oxides include, for example, MgO, SrO, BaO, and RaO.
Examples of Group 4 element oxides include TiO ₂ , ZrO ₂ and HfO ₂ .
The content of these inorganic oxides can be appropriately selected within a range that does not impair the effects of the present invention, and preferred embodiments are as follows.
The content of Group 2 element oxides other than calcium oxides is preferably 15% by mass or less, more preferably 13% by mass or less, from the viewpoint of improving the particle strength and peel strength of the coating film, and further 11% by mass or less. preferable.
The content of the Group 4 element oxide is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, from the viewpoint of improving the particle strength and the peel strength of the coating film.
In addition, the lower limit of the content of the group 2 element oxide and the group 4 element oxide other than the calcium oxide may be 0% by mass.

The inorganic oxide hollow particles of the present invention are characterized by being minute. More specifically, the particle size distribution can have the following characteristics. As used herein, the term "particle size distribution" refers to a volume-based particle size distribution measured according to JIS R 1629 "Method for measuring particle size distribution of fine ceramic raw materials by laser diffraction/scattering method". The particle size distribution is represented by a distribution curve in which the horizontal axis is the particle diameter (μm) and the vertical axis is the volume-based frequency (%). For example, Microtrac (manufactured by Nikkiso Co., Ltd.) can be used as a particle size distribution measuring device using a laser diffraction/scattering method.
The cumulative 100% particle diameter (D ₁₀₀ ) in the volume-based particle size distribution is preferably 15 µm or less, more preferably 13 µm or less, from the viewpoints of miniaturization, particle strength, and improvement in peel strength of the coating film. The lower limit of D ₁₀₀ is preferably 5 μm or more, more preferably 6 μm or more, still more preferably 7 μm or more, from the viewpoint of improving heat insulation performance and dielectric properties.
The cumulative 10% particle diameter (D ₁₀ ) in the volume-based particle size distribution is preferably 0.1 μm or more, more preferably 0.3 μm or more, from the viewpoint of uniforming the particle size and improving the peel strength of the coating film. and more preferably 0.5 μm or more. The upper limit of D ₁₀ is preferably 3.0 µm or less, more preferably 2.0 µm or less, and still more preferably 1.5 µm or less, from the viewpoint of improving particle strength.
The cumulative 50% particle size in the volume-based particle size distribution, that is, the average particle size (D ₅₀ ) is preferably 0.5 μm or more, more preferably 1.0 μm or more, from the viewpoint of miniaturization and uniformity of particle size. and more preferably 1.5 μm or more. The upper limit of _D50 is 5 µm or less, more preferably 4.5 µm or less, still more preferably 4.0 µm or less, from the viewpoint of improving particle strength.
The cumulative 90% particle diameter (D ₉₀ ) in volume-based particle size distribution is preferably 3.0 μm or more, more preferably 3.5 μm or more, from the viewpoint of miniaturization and uniformity of particle size. The upper limit of D ₉₀ is 10 µm or less, more preferably 9.5 µm or less, from the viewpoint of improving particle strength.

Further, the inorganic oxide hollow particles of the present invention are characterized by having a unimodal particle size distribution and a sharp shape.
An example of the particle size distribution of the inorganic oxide fine hollow particles of the present invention is shown in FIG. Inorganic oxide hollow particles generally have a broad particle size distribution with a large particle size gradient as shown in Comparative Example 1 in FIG. On the other hand, the inorganic oxide fine hollow particles of the present invention are composed of particles with a small particle size, excluding particles with a large particle size, in the particle size distribution, as shown in Example 4 of FIG. It consists of a single peak with a sharp shape. As described above, the inorganic oxide hollow particles of the present invention are composed of fine particles and have a uniform particle size, so that the particle strength is improved, and when a coating film is formed using a binder, the particles are mixed with the binder. As a result of the particles being evenly dispersed and the binder being sufficiently filled between the particles, the adhesion of the coating film is enhanced and it becomes difficult to peel off.

Furthermore, as described above, the inorganic oxide hollow particles of the present invention are characterized by having a sharp particle size distribution and a particle size gradient of 2 or less calculated by the following formula (1). .

Particle size gradient = (D ₉₀ - D ₁₀ )/D ₅₀ (1)

[In the formula, D ₉₀ represents the cumulative 90% particle size in the volume-based particle size distribution, D ₁₀ represents the cumulative 10% particle size in the volume-based particle size distribution, and D ₅₀ represents the cumulative 50% in the volume-based particle size distribution. Particle size is indicated. ]

The particle size gradient is preferably 1.8 or less, more preferably 1.7 or less, and even more preferably 1.6 or less, from the viewpoint of uniforming the particle size and further improving the peel strength of the coating film. The lower limit of the particle size gradient is preferably 1.0 or more, more preferably 1.1 or more, and even more preferably 1.2 or more, from the viewpoint of improving filling properties during resin kneading.

In addition, the thickness of the outer shell portion of the inorganic oxide hollow particles of the present invention is preferably 50 nm or more, more preferably 100 nm or more, and preferably 1 μm or less, further preferably 500 nm or less. By setting the thickness of the outer shell portion within the above range, the hollow portion can be sufficiently secured without impairing the particle strength, so that the heat insulation performance, dielectric properties, etc. can be improved. The thickness of the outer shell can be measured from a scanning electron microscope (SEM) image.

The hollowness of the inorganic oxide hollow particles of the present invention is preferably 70% or more, more preferably 75% or more, and still more preferably 80% or more, from the viewpoint of improving heat insulating performance, dielectric properties, and the like. The upper limit of the hollowness is preferably 95% or less, more preferably 90% or less, from the viewpoint of ensuring sufficient particle strength. Here, in the present specification, the "hollowness ratio" shall be obtained from the apparent density and the true density measured by a densitometer by the following formula. The "true density" shall be measured with a density meter after heating and cooling for 6 hours at the melting point or higher in a box-type electric furnace in order to remove voids. Also, as a density meter, for example, a dry automatic density meter Accupic (Shimadzu Corporation) can be used.

Hollowness ratio = (1-apparent density / true density) x 100

The shape of the inorganic oxide hollow particles of the present invention may be either a perfect sphere or a substantially spherical shape such as oblate ellipsoid or long ellipsoid. From the viewpoint of improving dielectric properties, the average circularity is preferably 0.85 or more, more preferably 0.90 or more. Here, the "circularity" is obtained by measuring the projected area (A) and perimeter (PM) of a particle from a scanning electron micrograph, and taking the area of a perfect circle with respect to the perimeter (PM) as (B). Particle circularity is expressed as A/B. Therefore, the perimeter and area of a perfect circle having the same perimeter as the sample particle perimeter (PM) are PM=2πr and B=πr ² respectively, so B=π×(PM/2π) ² . , the circularity of this particle is calculated as circularity=A/B=A×4π/(PM) ² . Circularity is measured for 100 particles, and the average value is defined as the average circularity.

From the viewpoint of ensuring sufficient strength, the particle strength of the inorganic oxide hollow particles of the present invention is preferably 18 MPa or higher, more preferably 20 MPa or higher, and even more preferably 23 MPa or higher. Here, the term "particle strength" as used herein means the particle strength when the residual ratio of inorganic oxide phosphor hollow particles is 50% when applying pressure to the hollow particles with a pressure molding press. Specifically, it can be measured by the method described in Examples below.

In addition, the inorganic oxide hollow particles of the present invention, when measured in accordance with JIS K 6854-1 for a substrate with a copper plate produced by a predetermined method using it, the resin layer from the copper plate 90 degrees The peel bond strength can preferably be greater than 10 N/m. As described above, since the inorganic oxide micro hollow particles of the present invention are fine and uniform in particle size, when the particles are dispersed in the binder, the binder is sufficiently filled between the particles, and the adhesion of the coating film is enhanced. It becomes difficult to peel off. The method for producing the base material with a copper plate follows the method described in the examples below.

The inorganic oxide hollow particles of the present invention can be applied to heat insulating materials, heat shielding materials, catalyst carriers, building materials, electronic materials and the like. In particular, the inorganic oxide hollow particles of the present invention are microparticles having a uniform particle size and excellent particle strength and coating peel strength, and are therefore useful for electronic materials, especially wiring circuit boards, semiconductor sealing materials, and the like. be.

Moreover, since the inorganic oxide hollow particles of the present invention are fine particles, they are excellent in dispersibility in a medium.
Although the medium is not particularly limited, examples thereof include resins, paints, rubbers, and solvents in that the effects of the present invention can be easily obtained.
When a resin is used as the medium, it can be a resin composition for forming an electronic material such as a wiring circuit board or a semiconductor sealing material. The resin is not particularly limited as long as it is commonly used in the fields of wiring circuits and semiconductor sealing materials.

The content of the inorganic oxide hollow particles in the resin composition can be appropriately selected depending on the application, but is usually 1 to 97% by mass, preferably 5 to 60% by mass, more preferably 15 to 40% by mass. % by mass.

Moreover, the resin composition may be in the form of a varnish dissolved or dispersed in an organic solvent, and a base material may be impregnated with the varnish to form a prepreg.
The solid content (non-volatile content) concentration in the varnish can be appropriately selected according to its use, but it is usually 5 to 80% by mass, preferably 10 to 70% by mass.
The substrate to be impregnated with the varnish is not particularly limited, and examples thereof include inorganic fibers, organic fibers, carbon fibers and the like. The impregnation can be performed by immersion (dipping), application, or the like.

Furthermore, for example, after applying the above-described varnish on a substrate with metal foil, heating and curing are performed to form a resin layer on the metal substrate, and then the metal is removed by etching to form a conductor pattern. A wired circuit board can also be manufactured. When applying the varnish on the base material, an appropriate coating method such as a spray method, roll coating method, spin coating method (spin coating method), slit die coating method (slit coating method), bar coating method, etc. can be used. can be adopted.

The method of mixing the medium and the inorganic oxide hollow particles is not particularly limited. kneading is done. In addition, mixing conditions can be appropriately set according to the mixing method.

The method for producing inorganic oxide hollow particles of the present invention is not particularly limited as long as the inorganic oxide hollow particles having the above configuration can be obtained. and a method of thermally decomposing the sprayed liquid droplets (mist).

Examples of raw material compounds include compounds containing one or more elements selected from alkali metals, calcium, silicon, boron and aluminum as elements constituting oxides. Such a compound is not particularly limited as long as it is a compound that dissolves in water. Examples thereof include inorganic salts, organic salts, and alkoxides, and may contain one or more. Inorganic salts include, for example, nitrates, sulfates, carbonates, hydroxides, and halides. Organic salts include, for example, formates, acetates, propionates, oxalates, and citrates.

Examples of alkali metal-containing compounds include lithium-containing compounds, sodium-containing compounds, potassium-containing compounds, rubidium-containing compounds, and cesium-containing compounds. Among them, one or more selected from lithium-containing compounds, sodium-containing compounds and potassium-containing compounds is preferable from the viewpoint of miniaturization, uniformity of particle size, improvement of particle strength and peel strength of coating film, and sodium-containing compounds are More preferred. Specific examples of sodium-containing compounds include sodium salts such as sodium nitrate, sodium chloride, sodium hydroxide, sodium sulfate, and sodium borate. Specific examples of the alkali metal-containing compound other than the sodium-containing compound include salts similar to those of the sodium-containing compound.

Calcium-containing compounds include, for example, calcium salts. Calcium salts include, for example, calcium nitrate, calcium chloride, calcium hydroxide, calcium formate, calcium acetate, and calcium propionate.
Boron-containing compounds include, for example, borates and boric acid. Examples of the borate include metaborate such as sodium borate and potassium borate, tetraborate such as sodium tetraborate and potassium tetraborate, pentaborate such as sodium pentaborate and potassium pentaborate. and acid salts.

Silicon-containing compounds include, for example, silicic acid alkoxides. Silicic acid alkoxides include, for example, tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), tetrapropyl orthosilicate (TPOS), and tetrabutoxysilane.
Examples of aluminum-containing compounds include aluminum salts and aluminum alkoxides. Examples of aluminum salts include aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum phosphate, aluminum hydroxide, aluminum acetate, and aluminum oxalate. Examples of aluminum alkoxides include aluminum methoxide, aluminum ethoxide and aluminum isopropoxide.
Silicon and aluminum containing compounds can include, for example, aluminosilicates. Examples of aluminosilicates include sodium aluminosilicate, potassium aluminosilicate, and calcium aluminosilicate.
A solution of aluminum oxide or silicon oxide dispersed in a solvent, or a sol solution of aluminum oxide or silicon oxide can also be used as the raw material compound solution.

In the present invention, the starting compounds may further contain compounds containing elements other than alkali metals, calcium, silicon, boron and aluminum.
Such a compound is not particularly limited as long as it is a metal compound that dissolves in water. Group 2 element-containing compounds other than calcium-containing compounds include, for example, magnesium salts, strontium salts, barium salts, and radium salts. Examples of Group 4 element-containing compounds include titanium salts, zirconium salts, and hafnium salts. Other examples include zinc salts and yttrium salts. One or more of these compounds can be used. Examples of salts of these metals include inorganic salts, organic salts, and alkoxides, and specific examples thereof are as described above.

Among these raw material compounds, one or more selected from alkali metal salts, calcium salts, silicate alkoxides, aluminum alkoxides, aluminosilicates, borates and boron, since the effects of the present invention are easily received; If necessary, it preferably contains one or more selected from magnesium salts, strontium salts, barium salts, titanium salts and zirconium salts.

The liquid to be sprayed can be prepared by mixing the raw material compound with water or an organic solvent such as ethanol. The mixing ratio of the raw material compounds may be appropriately adjusted according to the kind of the raw material compounds so as to obtain the inorganic oxide fine hollow particles having the composition described above.

The raw material compound concentration in the liquid to be sprayed is preferably 0.01 mol/L to 2.0 mol/L, more preferably 0.1 mol/L to 1.0 mol/L, as the total amount of each element.

In the spray pyrolysis apparatus, the pyrolysis furnace preferably has a rigid cylindrical shape, and the size of the pyrolysis furnace can be appropriately selected depending on the production scale.

Examples of spray devices include fluid nozzles such as two-fluid nozzles, three-fluid nozzles, and four-fluid nozzles. Here, the fluid nozzle system includes an internal mixing system in which the gas and the raw material solution are mixed inside the nozzle and an external mixing system in which the gas and the raw material solution are mixed outside the nozzle, and both can be employed. As the gas supplied to the nozzle, for example, air, inert gas such as nitrogen or argon, or the like can be used. Among them, air is preferable from the viewpoint of economy. One or two or more spray devices can be installed.

The flow rate of the liquid to be sprayed is generally 1 to 100 L/h, preferably 3 to 80 L/h, more preferably 5 to 60 L/h.

The droplets sprayed from the spraying device are heated by the heating device in the pyrolysis furnace to form a film containing an inorganic compound, starting from which inorganic oxide hollow particles are formed.
The ejection speed of droplets is usually 1 to 50 m/s, preferably 5 to 35 m/s, more preferably 10 to 20 m/s.

Examples of the heating device include combustion burners, hot air heaters, electric heaters, and the like. One or more heating devices can be installed. Any commercially available combustion burner, hot air heater, and electric heater can be used.
The temperature of the heating device is preferably 400 to 1800°C, more preferably 600 to 1500°C, even more preferably 700 to 1400°C, and even more preferably 800 to 1200°C. At such a temperature, thermal decomposition is sufficient, and the particles are less likely to agglomerate when discharged from the thermal decomposition furnace.

The inorganic oxide hollow particles produced by the pyrolysis reaction are recovered from the downstream side of the pyrolysis furnace. Inorganic oxide hollow particles can be recovered by using a high-performance cyclone powder recovery machine or a powder recovery device using a bag filter.

EXAMPLES The embodiments of the present invention will now be described more specifically with reference to Examples. However, the present invention is not limited to the following examples.

1. Analysis of chemical composition Inorganic oxide hollow particles are molded with a press to produce briquettes, and the briquettes are measured in terms of oxides with a fluorescent X-ray analyzer (ZSX primus II, manufactured by Rigaku) to calculate chemical components. did.

2. Measurement of Particle Size Distribution, Calculation of Particle Size Gradient Using a particle size distribution analyzer (MT3000II, manufactured by Microtrack Bell), a volume-based particle size distribution was created in accordance with JIS R 1629, and D ₁₀₀ , D ₉₀ , D ₅₀ , D ₁₀ , and the particle size gradient was calculated by the following formula (1).

Particle size gradient = (D ₉₀ - D ₁₀ )/D ₅₀ (1)

[In the formula, D ₉₀ represents the cumulative 90% particle size in the volume-based particle size distribution, D ₁₀ represents the cumulative 10% particle size in the volume-based particle size distribution, and D ₅₀ represents the cumulative 50% in the volume-based particle size distribution. Particle size is indicated. ]

3. Measurement of Particle Strength Particle strength was measured by the following powder pressing method.
(1) Hollow particles and ethanol were mixed at a mass ratio of 4:1 to prepare a sample.
(2) The sample was placed in a pressure former, and a predetermined pressure (10 MPa, 20 MPa, 30 MPa) was applied with a hydraulic press.
(3) Leave for 1 minute while a predetermined pressure is applied.
(4) The sample was removed from the pressure former and dried at 80°C for 2 hours.
(5) Using a microcompression tester (MCT-510, manufactured by Shimadzu Corporation), the density of the hollow particles after compression was measured.

Then, from the density of the hollow particles before and after pressurization, the residual rate for each predetermined pressure was calculated by the following formula, and the pressure at 50% residual was read from the graph of the residual rate and the applied pressure. The density was measured using the above-described density measuring instrument, and the true density of the hollow shell was measured after heating at the melting point or higher for 6 hours in a box-shaped electric furnace and cooling in order to remove voids.

Survival rate P [%] = (1-ρ/y)/ρ x (1/x-1/y) x 100

[In the formula, ρ represents the density after pressing, y represents the true density of the hollow shell, and x represents the density before pressing. ]

4. Test of 90 degree peel adhesive strength A test piece prepared by the following method is set in a 90 degree peel tester (P90-200N, manufactured by Imada Co., Ltd.), JIS K 6854-1: 50 mm in accordance with 1999 /min, the 90-degree peel adhesion strength of the resin layer from the copper plate was measured and evaluated according to the following criteria.

[Preparation of test piece with copper plate]
5 g of dry powder of inorganic oxide fine hollow particles, 30 g of a mixture of liquid bisphenol A type epoxy resin and liquid bisphenol F type epoxy resin (average epoxy equivalent: 165 g/mol), 20 g of liquid phenol novolak (hydroxy group equivalent: 135 g/mol), and 1 g of triphenylphosphine was added to and mixed with the mixed epoxy resin liquid. The resin mixture is applied on a flexible adherend bent at right angles and coated with a width of 25 mm, a length of 150 mm, and a thickness of 1 mm. was added to adhere. Then, it was dried and cured in a dryer at 80° C. for 12 hours to prepare a test piece.

〔Evaluation criteria〕
○: 90 degree peeling adhesive strength is over 10 N / m ×: 90 degree peeling adhesive strength is 10 N / m or less

Examples 1 to 6 and Comparative Examples 1 and 2
Raw material compounds (colloidal silica, tetraethyl orthosilicate, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate, calcium nitrate tetrahydrate, boric acid, sodium tetraborate decahydrate) in 30 liters of distilled water, It was dissolved so as to have the molar concentration shown in Table 1, and the raw material compound aqueous solution was put into the solution tank. Next, the charged raw material compound aqueous solution was sent to a two-fluid nozzle by a liquid sending pump, sprayed in a mist state, and heated in a furnace (1000° C.). The operating conditions of the two-fluid nozzle were a nozzle air amount of 100 L/min and a liquid feed amount of 67 mL/min. Then, it was quenched by a cooling mechanism installed at the outlet of the reaction zone of the furnace, and then the inorganic oxide hollow particles were collected using a bag filter.

The resulting inorganic oxide hollow particles were analyzed for chemical composition and particle size, and evaluated for particle strength and 90-degree peel adhesive strength. These results are shown in Table 2. In addition, the particle size distribution of the inorganic oxide hollow particles obtained in Example 4 and Comparative Example 1 is shown in FIG.

From Table 2, it can be seen that the inorganic oxide hollow particles of this example not only have a small particle diameter and a uniform particle size, but also have excellent particle strength and are difficult to peel off when a resin composition that is a coating film is formed. I understand.

Claims (8)

An inorganic oxide fine hollow particle having a shell defining a hollow chamber,
The content of the alkali metal oxide is 2% by mass or less,
The content of calcium oxide is 5% by mass or less,
The total content of silicon oxide, boron oxide and aluminum oxide is 50% by mass or more,
The particle size distribution is unimodal, and the following formula (1);
Particle size gradient = (D ₉₀ - D ₁₀ )/D ₅₀ (1)
[In the formula, D ₉₀ represents the cumulative 90% particle size in the volume-based particle size distribution, D ₁₀ represents the cumulative 10% particle size in the volume-based particle size distribution, and D ₅₀ represents the cumulative 50% in the volume-based particle size distribution. Particle size is indicated. ]
The particle size gradient calculated by is 2 or less,
Inorganic oxide micro hollow particles. 2. The inorganic oxide fine hollow particles according to claim ₁ , wherein D100 is 15 [mu]m or less. 3. The inorganic oxide fine hollow particles according to claim 1, wherein D ₅₀ is 0.5 to 5 μm. The inorganic oxide fine hollow particles according to any one of claims 1 to 3, wherein the silicon oxide content is 20 to 70% by mass. The inorganic oxide fine hollow particles according to any one of claims 1 to 4, wherein the content of boron oxide is 15 to 35% by mass. The inorganic oxide fine hollow particles according to any one of claims 1 to 5, wherein the content of aluminum oxide is 5 to 20% by mass. For a test piece with a copper plate prepared by the following method, when measured in accordance with JIS K 6854-1, the 90 degree peel adhesion strength of the resin layer from the copper plate is greater than 10 N / m, claims 1- 7. The inorganic oxide fine hollow particles according to any one of 6.
[Preparation of test piece with copper plate]
5 g of dry powder of inorganic oxide fine hollow particles, 30 g of a mixture of liquid bisphenol A type epoxy resin and liquid bisphenol F type epoxy resin (average epoxy equivalent: 165 g/mol), 20 g of liquid phenol novolak (hydroxy group equivalent: 135 g/mol), and 1 g of triphenylphosphine is added to the mixed epoxy resin liquid and mixed. The resin mixture is applied on a flexible adherend bent at right angles and coated with a width of 25 mm, a length of 150 mm, and a thickness of 1 mm. and glue. After that, it is dried and cured in a dryer at 80° C. for 12 hours to prepare a test piece. A resin composition comprising the inorganic oxide hollow particles according to any one of claims 1 to 7.

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