JP2002012428A - Method of producing glass powder and glass powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing glass powder having fine spherical form easily. SOLUTION: This method comprises the steps of mixing a SiO2 sol containing at least one of dihydric or trihydric alcohols as the solvent with an aqueous solution of a compound containing a glass-forming element other than Si, and thermally treating the mixed solution through pyrolytic spraying, wherein the compound containing a glass-forming element being preferably an aqueous polyester oligomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fine spherical glass powder and a glass powder.

[0002]

2. Description of the Related Art Conventionally, as a method for producing glass powder, a melt-quenching-pulverization method is the most common method. That is, both the main raw material (silicon oxide, alumina, alkali metal compound, etc.) constituting the glass and the auxiliary raw material which affects the melting temperature and physical properties (crystallization temperature, thermal expansion coefficient, dielectric constant, etc.) of the glass are combined. placed in a container such as a platinum crucible, melted by heating at the melting point of the glass (viscosity 10 ³ ~ ⁴ dPa / s or less to become temperature) than 200 to 300 [° C. higher temperature melting furnace and thoroughly homogenized, clarified Thereafter, the glass powder was put into water, rapidly cooled, vitrified, and then pulverized to produce glass powder.

[0003]

However, since the glass powder obtained by the conventional method is pulverized by mechanical pulverization, the shape of the obtained powder is irregular. For example, when a laminate comprising a conductor layer and a non-conductor layer (particularly a laminate having a thin conductor layer) is produced using such a glass powder, the amorphous glass powder in the non-conductor layer is used. There is a problem that the conductive layer is pierced at the sharp tip. Further, the molded article using the amorphous glass powder has a problem that voids are easily generated and the density of the molded article is reduced.

On the other hand, Japanese Patent Application Laid-Open No. 8-91 discloses a method for producing a spherical glass powder which does not easily cause the above-mentioned problems.
No. 874 discloses a method using a spray pyrolysis method. Then, in the spray pyrolysis method in which the thermal decomposition reaction of the spray droplets is caused by radiant heat, hollow glass powder is generated, but by the spray pyrolysis method in which the droplets are sprayed in a flame atmosphere, it is solid and spherical. It is said that a glass powder having a shape can be obtained.

However, in the case of the conventional spray pyrolysis method as disclosed in JP-A-8-91874, the average particle size of the obtained glass powder is at most about 1 μm, A spherical glass powder could not be obtained.

Accordingly, an object of the present invention is to solve the above problems and to provide a method for easily producing fine spherical glass powder. Another object of the present invention is to provide a fine spherical glass powder.

[0007]

In order to achieve the above object, a method for producing a glass powder according to the present invention comprises an SiO ₂ sol containing at least one of dihydric and trihydric alcohols as a solvent; _{(2) The} method is characterized in that a mixed solution of an aqueous solution of a compound containing a glass-forming element other than the Si element contained in the sol is heat-treated by a spray pyrolysis method.

The compound containing the glass-forming element is at least one of chloride, nitrate, acetate, sulfate and formate.

Further, the compound containing a glass-forming element is a water-soluble polyester oligomer.

[0010] The total concentration of the SiO ₂ and the compound containing the glass-forming element in terms of oxide in the mixed solution is 10% by weight or less.

Further, when the total concentration of SiO ₂ and the compound in terms of oxide in the mixed solution is 3% by weight or less, the droplet diameter is atomized to 1 μm or less, and the total concentration is 10% by weight or less. When it exceeds 3% by weight, the droplet diameter is 0.5
It is a spray pyrolysis method in which it is atomized to a size of not more than μm and then pyrolyzed.

Further, the glass powder of the present invention contains a SiO ₂ sol containing at least one of dihydric and trihydric alcohols as a solvent, and a glass-forming element other than the Si element contained in the SiO ₂ sol. mixed solution of an aqueous solution of compound, wherein if the total concentration of the oxide concentration in terms of SiO ₂ and the compound is 3 wt% or less atomized below droplet diameter 1 [mu] m, a total concentration of 10 wt% or less If it exceeds 3% by weight, it is atomized to a droplet diameter of 0.5 μm or less and then pyrolyzed to obtain an average particle diameter of 0.2 μm.
It is the following glass powder.

The dihydric or trihydric alcohol as a solvent for the SiO ₂ sol includes ethylene glycol,
Properly use propylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, dipropylene glycol, triglycol, tetraethylene glycol, butanediol-1,4-hexylene glycol, octylene glycol, 1,2,3-propyltriol, etc. Can be.

As commercially available organic solvents for the SiO ₂ sol, methanol, ethanol, n-propanol, i-propanol, ethylcellosolve, n-butanol and the like are used. However, these S
When the iO ₂ sol is added and dispersed in a weakly acidic to weakly alkaline solution, the iO ₂ sol is aggregated and the dispersibility is reduced. On the other hand, when a dihydric or trihydric alcohol is used as a solvent for the SiO ₂ sol, aggregation does not occur even when added and dispersed in a weakly acidic to weakly alkaline solution, and a highly dispersed state is maintained. Therefore, even in the case of spray pyrolysis of very fine droplets, since the elements constituting the glass are uniformly mixed, the composition shift hardly occurs, and a fine spherical glass powder can be obtained.

In order to heat-treat the mixed solution by the spray pyrolysis method, for example, an ultrasonic vibration method, an electrostatic atomization method, Various known atomization methods such as a two-fluid nozzle method can be used as appropriate. Among them, an electrostatic atomization method capable of atomizing into finer droplets is suitable for obtaining fine glass powder. The method of the present invention does not require a conventional pulverizing step after vitrification, and can prevent contamination by impurities caused by the pulverizing step.

Further, by setting the heat treatment temperature by the spray pyrolysis method to be equal to or higher than the melting point of the glass, spherical fine glass powder can be obtained.

As the compound containing a glass-forming element, any compound soluble in water can be used. Representative water-soluble compounds include acetate, formate, chloride, nitrate, and the like. Further, an oxide, a carbonate, or the like can be dissolved in an acid or the like before use.

Further, by using a water-soluble polyester oligomer as a compound containing a glass-forming element,
The composition of the atomized droplets can be made uniform, and finer spherical glass powder can be obtained. That is,
When using a mixed solution of individual compounds forming glass-forming elements,
The problem that the composition of the atomized droplets may become non-uniform due to the difference in the solubility of each compound is solved.

As the oxycarboxylic acid for producing the water-soluble polyester oligomer, citric acid can be cited as a typical example. In addition, malic acid, grape acid, meconic acid, meso-tartaric acid and the like can be mentioned. Acids can be used as appropriate. In addition, starting materials containing a glass-forming element used for producing a water-soluble polyester oligomer include carbonates that are decomposed and dissolved by oxycarboxylic acid, chlorides, nitrates, acetates, sulfates, and formic acids that are soluble in water. A salt or the like can be used as appropriate.

The average particle size of the glass powder obtained can be suppressed to 0.2 μm or less by using an atomization method such as an electrostatic atomization method capable of reducing the droplet diameter to 1 μm or less.

Further, the total concentration of the compound containing SiO ₂ and the glass-forming element in terms of oxide in the mixed solution is preferably suppressed to 10% by weight or less. If the content exceeds 10% by weight, the viscosity of the mixed solution increases, and depending on the atomization method, it is not possible to generate fine droplets. Since it is too high, the particle size of the obtained powder tends to be large and irregular.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
A description will be given based on an embodiment.

Example 1 First, barium carbonate, lithium carbonate and boron oxide were prepared as starting materials. Next, each raw material is accurately weighed and weighed so that the molar ratio of glass forming element Ba: Li: B becomes 0.45: 0.85: 1.00, and then nitric acid is added to dissolve the raw materials. Let
A nitrate aqueous solution was prepared. Then, a SiO ₂ sol containing ethylene glycol as a solvent was added to this nitrate aqueous solution.
77 mol and pure water were added, and the mixed solution was sufficiently stirred to prepare a mixed solution having a concentration of 0.1 to 5% by weight in terms of oxide.

Next, in a vertical spray pyrolysis furnace adjusted to 1000 ° C., the mixed solution atomized by an ultrasonic vibration method is
A thermal decomposition reaction was caused by blowing in a mist at a rate of 60 mL / hour, and then cooled to obtain a SiO ₂ —B ₂ O ₃ —BaO—Li ₂ O-based glass powder shown in Sample Nos. 1 to 4 in Table 1. Obtained.

Example 2 First, the molar ratio of the elements was Si:
Li: Ba: Sr: Ca: Al: Ti = 1.00: 1.
19: 0.16: 0.12: 0.11: 0.05: 0.
As starting materials for glass of No. 07, lithium carbonate, barium carbonate, strontium carbonate and calcium carbonate were prepared. Next, each raw material is accurately weighed and weighed so that the molar ratios of Li, Ba, Sr, and Ca elements become the above values, and then 1000 ml of pure water is added, and the raw materials are further dissolved. 1.25 times the amount of malonic acid was added thereto, and the mixture was stirred and dissolved.

Next, a (Ti, Al) composite alkoxide synthesized by a conventional method was added to the obtained solution, and the mixture was coordinated with malic acid for stabilization. Further, a SiO ₂ sol using ethylene glycol as a solvent was added to carry out condensation polymerization of malic acid and ethylene glycol to produce a water-soluble polyester oligomer. Thereafter, pure water was added to prepare a mixed solution having a concentration of 0.1 to 5% by weight in terms of oxide.

Next, the mixed solution atomized by an ultrasonic vibration method was placed in a vertical spray pyrolysis furnace adjusted to 1200 ° C.
A pyrolysis reaction was caused by blowing in a mist at a rate of 60 mL / hour, and then cooled, and then cooled to SiO ₂ —Li ₂ O—BaO—SrO—CaO—Al ₂ shown in sample numbers 5 to 8 in Table 1.
It was obtained O ₃ -TiO ₂ -based glass powder.

Example 3 First, the molar ratio of the elements was
i: B: Ca: Al = 1.00: 0.23: 1.12:
As a starting material for the glass of 0.18, boron oxide,
Calcium carbonate and aluminum nitrate were provided. Next, each raw material is accurately weighed and weighed so that the molar ratios of the B, Ca and Al elements become the above values, and then 1000 ml of pure water is added, and the equivalent amount required to further dissolve the raw material is added. 1.25 times the amount of citric acid was added and stirred,
Decomposed and dissolved.

Next, an SiO ₂ sol using ethylene glycol as a solvent was added to the obtained solution to cause condensation polymerization of citric acid and ethylene glycol to produce a water-soluble polyester oligomer. Thereafter, pure water was added to prepare a mixed solution having a concentration of 0.1 to 15% by weight in terms of oxide.

Next, the mixed solution atomized by the electrostatic atomization method was placed in a vertical spray pyrolysis furnace adjusted to 1200 ° C. for 2 hours.
0 mL / to cause a thermal decomposition reaction blown to mist at a time rate, and then cooled, a _{SiO 2 -B 2 O 3 -CaO-} Al 2 O 3 based glass in samples 9 to 14 in Table 1 A powder was obtained.

The particle size of the atomized droplets in Example 3 was about 0.5 μm when the generated fine droplets were adhered to a cooled glass plate and immediately observed using an optical microscope. there were.

Example 4 First, the molar ratio of the elements was Si:
Li: Ba: Sr: Ca: Al: Ti = 1.00: 1.
19: 0.16: 0.12: 0.11: 0.05: 0.
As starting materials for glass No. 07, lithium carbonate, barium carbonate, strontium carbonate, calcium carbonate and aluminum nitrate were prepared. Next, each raw material is
After accurately weighing and dispensing each such that the molar ratios of i, Ba, Sr, Ca and Al elements become the above values, pure water 1
000 ml was added, and then 1.25 times the amount of grape acid required for dissolving the raw materials was added, followed by stirring and dissolution.

Next, a titanium alkoxide was added to the obtained solution, and the mixture was coordinated with grape acid to perform stabilization. Further, an SiO ₂ sol using propylene glycol as a solvent was added thereto, and condensation polymerization of the grape acid and propylene glycol was carried out to produce a water-soluble polyester oligomer. Thereafter, pure water was added, and the concentration in terms of oxide was 0.1
A mixed solution of ５5% by weight was prepared.

Next, the mixed solution atomized by the electrostatic atomization method was placed in a vertical spray pyrolysis furnace adjusted to 1200 ° C. for 3 hours.
A pyrolysis reaction was caused by blowing in the form of a mist at a rate of 0 mL / hour, and then cooled, followed by cooling to SiO ₂ —Li ₂ O—BaO—SrO—CaO—Al shown in Sample Nos. 15 to 19 in Table 1.
₂ O ₃ —TiO ₂ glass powder was obtained.

In the present embodiment, the particle size of the atomized droplet is about 0.9 μm when the generated fine droplet is attached to a cooled glass plate and immediately observed using an optical microscope. Was.

Comparative Example 1 First, barium carbonate, lithium carbonate and boron oxide were prepared as starting materials. Next, each raw material is accurately weighed and weighed so that the molar ratio of glass forming element Ba: Li: B becomes 0.45: 0.85: 1.00, and then nitric acid is added to dissolve the raw materials. Let
A nitrate aqueous solution was prepared. Thereafter, 0.77 mol of SiO ₂ sol using isopropyl alcohol as a solvent and pure water are added to the nitrate aqueous solution, and the mixture is sufficiently stirred to prepare a mixed solution having a concentration of 0.1 and 0.5% by weight in terms of oxide. did. At this time, the mixed solution became slightly cloudy.

Next, in the same manner as in Example 1, by spray pyrolysis, the SiO 2 shown in Sample Nos. 20 and 21 in Table 1 was used.
To obtain a _{2 -B 2 O 3 -BaO-Li} 2 O glass powder.

(Comparative Example 2) First, the molar ratio of the elements was S
i: B: Ca: Al = 1.00: 0.23: 1.12:
As a starting material for the glass of 0.18, boron oxide,
Calcium carbonate and aluminum nitrate were provided. Next, each raw material was accurately weighed and weighed so that the molar ratios of the B, Ca and Al elements became the above values, and then nitric acid was added to dissolve the raw materials to prepare a nitrate aqueous solution. afterwards,
To this nitrate aqueous solution, 1.00 mol of SiO ₂ sol using isopropyl alcohol as a solvent and pure water are added, and the mixture is sufficiently stirred.
Was prepared. At this time, the mixed solution became slightly cloudy.

Next, in the same manner as in Example 3, by spray pyrolysis, the SiO 2 shown in Sample Nos. 22 and 23 in Table 1 was used.
To obtain a _{2 -B 2 O 3 -CaO-Al} 2 O 3 based glass powder.

The glass powders obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were subjected to a scanning electron microscope (SEM).
A photograph was taken to determine the particle size of the powder. In addition, X-ray diffraction (X
RD) An analysis method confirmed the formation of a glass (amorphous). Table 1 shows the results. Although not shown in Table 1, it was confirmed by scanning electron microscope (SEM) observation that the glass powders of Sample Nos. 1 to 23 were all spherical.

[0041]

[Table 1]

As is clear from Examples 1 to 4 in Table 1,
According to the method of the present invention, fine spherical glass powder can be obtained.

Specifically, a glass powder having the same composition was prepared in the same manner except that the solvent of the SiO ₂ sol was different, and a comparison between the examples and comparative examples (comparison of sample numbers 1 and 20, sample number 2) And 21; sample numbers 9 and 22; and sample numbers 10 and 23).
By using ethylene glycol, which is a dihydric alcohol, as a solvent of the SiO ₂ sol, a fine glass having a particle size of 1/3 to 1/6 compared with the case of using isopropyl alcohol, which is a monohydric alcohol. A powder can be obtained. The difference is that, in the case of the comparative example, when an aqueous nitrate solution of a compound containing a glass-forming element was added,
It is considered that aggregation of the O ₂ sol occurred.

As is clear from Sample Nos. 9 to 13 of Example 3 and Sample Nos. 15 to 18 of Example 4, the ratio of SiO ₂ in the mixed solution to the oxide equivalent of the compound containing the glass-forming element was calculated. If the total concentration is 3% by weight or less, atomize to a droplet diameter of 1 μm or less. If the total concentration is 10% by weight or more and exceeds 3% by weight, atomize to a droplet diameter of 0.5 μm or less. By adopting the spray pyrolysis method that decomposes, fine glass powder having an average particle size of 0.2 μm or less can be obtained.

In each of the above embodiments, SiO ₂
Although the case where ethylene glycol or propylene glycol which is a dihydric alcohol is used as the solvent of the sol is shown, the same effect can be obtained by using other dihydric alcohol or trihydric alcohol.

[0046]

As is apparent from the above description, according to the production method of the present invention, fine spherical glass powder having an average particle diameter of 0.2 μm or less can be easily obtained.

Continued on the front page F-term (reference) 4G014 AH01 AH02 AH11 AH12 4G062 AA10 BB01 CC06 CC08 DA02 DB02 DC02 DD01 DE01 DF01 EA02 EB01 EC01 ED01 EE02 EF02 EG02 FA01 FB02 FC01 FD01 FE01 FF01 GF01 F0101 01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 KK10 4G072 AA25 BB05 CC11 DD05 DD06 EE06 EE07 GG02 GG03 HH18 LL11 U11 RR01 U17

Claims (6)

[Claims] An SiO ₂ sol containing at least one of dihydric and trihydric alcohols as a solvent;
A method for producing glass powder, comprising heat-treating a mixed solution of a compound containing a glass-forming element other than the Si element contained in an O ₂ sol with an aqueous solution by a spray pyrolysis method. 2. The glass powder according to claim 1, wherein the compound containing the glass-forming element is at least one of chloride, nitrate, acetate, sulfate, and formate. Production method. 3. The method according to claim 1, wherein the compound containing a glass-forming element is a water-soluble polyester oligomer. 4. The total concentration of the SiO ₂ and the compound containing the glass-forming element in terms of oxide in the mixed solution is 10% by weight or less. 3. The method for producing a glass powder according to item 3. 5. When the total concentration of SiO ₂ and the compound in terms of oxide in the mixed solution is 3% by weight or less, the droplet diameter is atomized to 1 μm or less, and the total concentration is 10% by weight or less. 5. The method for producing a glass powder according to claim 4, wherein when the amount exceeds 3% by weight, a spray pyrolysis method of atomizing to a droplet diameter of 0.5 μm or less and then thermally decomposing is performed. 6. An SiO ₂ sol containing at least one of dihydric and trihydric alcohols as a solvent;
A mixed solution of an aqueous solution of a compound containing a glass forming element other than the Si element contained in the iO ₂ sol has a total concentration of 3% by weight of the SiO ₂ and the concentration of the compound in terms of oxide.
In the following cases, the liquid is atomized to a droplet diameter of 1 μm or less, and when the total concentration is 10% by weight or less and exceeds 3% by weight, the liquid is atomized to a droplet diameter of 0.5 μm or less and then thermally decomposed. Glass powder having an average particle size of 0.2 μm or less.