JPH10324539A - Fine spherical glass and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nonporous solid fine spherical glass less liable to cause the leaching of the alkali components and having high chemical durability by atomizing a slurry prepd. by dispersing powder of a silicate glass having a specified compsn. or a powdery starting material mixture in a combustible liq. and burning and melting the slurry. SOLUTION: Powder of a silicate glass consisting of 70-98 wt.% SiO2 , 0-15 wt.% B2 O3 , 0-5 wt.%, in total, of alkali metal oxides and alkaline earth metal oxides and 0-30 wt.% other metal oxides or a powdery starting material mixture for the silicate glass is dispersed in a combustible liq. to prepare a slurry having 150 wt.% concn. This slurry is atomized through a two-way nozzle, etc. burned and melted to obtain the objective nonporous solid fine spherical glass having <=30 μm particle diameter and a smooth surface. The average particle diameter or particle size distribution of the fine spherical glass is regulated by classification if necessary and the unnecessary part of the glass is recycled as starting material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

It relates BACKGROUND OF THE INVENTION The present invention microsphere glass and a manufacturing method thereof, and more particularly, be industrial mass and inexpensively manufactured in a conventional difficult, SiO ₂ is 70 to 98 wt% , B ₂ O _{3 from 0} to 15
% By weight, the total amount of alkali metal oxides and alkaline earth metal oxides is 0 to 5% by weight, and other metal oxides are 0 to 3% by weight.
0% by weight, and the total of the components is 100% by weight.
It has a small alkali elution and is useful as a filler for cosmetics and resins. The average particle size is 50 μm or less, especially 20 μm.
The present invention relates to a fine spherical glass having a diameter of not more than m and a method for producing the same.

[0002]

2. Description of the Related Art Soda-lime glass and aluminosilicate glass are known as microspherical glass. In terms of durability, aluminosilicate glass is excellent but not sufficient, and when blended with resin, under severe conditions, alkali components are eluted to deteriorate the resin, which is not preferable.

[0003] The method for producing a spherical solid body of fine glass is as follows: 1) A method in which ground and classified glass powder is melted in a high-temperature atmosphere, and is spheroidized by its surface tension. 2) A method of spheroidizing the ground and classified glass powder by rotating it in a high-temperature rotary kiln. 3) A method in which a molten glass liquid is sprayed and spheroidized by surface tension is known.

In the above methods 1 and 2, since the dried glass fine powder is dispersed in a high-temperature atmosphere, the glass powder is liable to agglomerate as the glass powder becomes smaller, and some particles are fused when the glass is melted. However, it was difficult to obtain a glass spherical solid having a small diameter and a uniform particle size distribution. In addition, since a dry pulverization operation or the like is used in the process of obtaining the glass powder,
This is an inefficient process because dust is generated, environmental pollution occurs, and pulverization requires a long time. In the method 3, the melt is rich in fluidity, such as a titanium-barium-based glass, and is limited to a glass having a low viscosity and a high surface tension. For these reasons, it has been difficult to industrially produce microsphere glass having a size of 50 μm or less, especially 20 μm or less at low cost in an industrial scale.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art.

It is another object of the present invention to reduce the elution of the alkali component, suppress the alteration of the coexisting substance at the compounding destination due to the alkali component, and fill the matrix material with a high filling amount. It is an object of the present invention to provide a fine, spherical, nonporous, microsphere glass having a wide range of application and capable of forming a molded article with little deformation, and a manufacturing method for industrially manufacturing the glass at low cost.

[0007]

SUMMARY OF THE INVENTION The present invention, SiO ₂ is 70 to 98 wt%, B ₂ O ₃ 0 to 15 wt%, the total of alkali metal oxides and alkaline earth metal oxides 0
5% by weight, 0 to 30% by weight of other metal oxides, and a silicate glass prepared so that the total of the components is 100% by weight. , SiO ₂ is 70 to 98 wt%, B ₂ O
₃ is 0 to 15% by weight, the total amount of alkali metal oxides and alkaline earth metal oxides is 0 to 5% by weight, the other metal oxides is 0 to 30% by weight, and the total of the components is 100%.
% Of silicate glass powder or a slurry obtained by dispersing a raw material mixed powder necessary for producing this silicate glass in a flammable liquid to form droplets. A method for producing the microspherical glass, which comprises burning and melting a slurry in the form of a microsphere.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The microspherical glass of the present invention is obtained by dispersing a silicate glass powder having a specific composition or a raw material mixed powder necessary for producing this silicate glass in a flammable liquid. The slurry is formed by making the resulting slurry into droplets, and burning and melting the droplet-shaped slurry. Hereinafter, the manufacturing method will be described.

(Raw Materials) In manufacturing the microspherical glass of the present invention, the necessary raw materials are silica, and boron oxide, alkali metal oxide, alkaline earth metal oxide and other metal oxides in the vitrification process. Is a compound necessary for producing silicate glass.

Examples of the silica include silica sand, silica gel, silica fume, and white carbon. Examples of the compound that becomes boron oxide in the vitrification step include sodium borate and boric acid. Examples of the compound that becomes an alkali metal oxide in the vitrification step include sodium sulfate, sodium carbonate, potassium sulfate, and potassium carbonate. , Lithium sulfate, and lithium carbonate. Examples of the compound that becomes an alkaline earth metal oxide in the vitrification step include calcium carbonate, calcium sulfate, dibasic calcium phosphate, magnesium carbonate, magnesium sulfate, and magnesium hydroxide. Barium sulfate and barium carbonate can be exemplified. Compounds that become other metal oxides in the vitrification process include:
Examples thereof include alumina, zinc oxide, zirconia, titanium dioxide, and lead oxide, but are not limited to these inorganic compounds, and may be organic compounds that become inorganic by combustion.

The raw materials used in the method of the present invention have an average particle size of 3 μm or less, preferably 3 to 0.0
It is preferably 1 μm, more preferably 1 to 0.01 μm. The average particle size of the raw material particles can be measured by a measuring method using a laser light scattering method known per se.

When the average particle size of the raw material particles exceeds 3 μm,
The raw material powder may settle without being uniformly dispersed in the flammable liquid, making it difficult to form slurry droplets.
Further, when the average particle size of the raw material powder is less than 0.01 μm, when the raw material powder is added to the flammable liquid, the raw material powder may aggregate and it may be difficult to prepare a uniform slurry.

When the average particle size of the raw material powder exceeds the above range, it is preferable to pulverize the raw material and adjust the average particle size so as to be within the above range.

The pulverizing method may be either dry pulverization or wet pulverization, but wet pulverization is preferred.
Wet grinding is easier to micronize than dry grinding,
Moreover, the surface smoothness of the fine spherical glass obtained by the method of the present invention can be improved, and there is no fear of environmental pollution due to dust. Furthermore, when this wet pulverization is employed, the slurry of the present invention can be prepared as a result of the pulverization operation, which is advantageous in terms of the process.

The wet pulverization is carried out by mixing an appropriate liquid and raw material powder. Wet grinding will be described in the following description of the slurry preparation process.

(Slurry Preparation Step) In the method of the present invention, a slurry is prepared by dispersing the raw material powder in a flammable liquid.

In the present invention, the powder of the silica-based raw material prepared to a predetermined particle size by dry pulverization and the flammable liquid may be mixed, but the particle size adjustment of the raw material and the slurry preparation are performed simultaneously. It is preferred to prepare the slurry by wet milling which can be performed.

As the flammable liquid used for preparing the slurry, the raw material in the slurry is melted together with the fuel used in the spray combustion step described later, and in some cases, the formed fine powder is sintered. The type is not particularly limited as long as it can generate the combustion temperature as much as possible, but in many cases, organic media such as hydrocarbons, kerosene, light oil, heavy oil, alcohol, ether, and ketone which are liquid at room temperature are often used. Is exemplified. From the viewpoint of handleability, the boiling point is 5
Flammable liquids at 0 ° C. or higher are preferred. Kerosene, light oil, heavy oil, and alcohol are particularly preferable as combustible liquids because they are easy to handle, cheap, and easy to burn, and the raw material is efficiently and uniformly heated during spray combustion.

If the fuel for burning the droplets formed by spraying the slurry and the flammable liquid are of the same type, the fuel used for spray combustion is prepared separately and used. This eliminates the necessity and simplifies the manufacturing process. Therefore, it is preferable that the flammable liquid during slurry preparation and the fuel during spray combustion be of the same type.

When preparing a slurry by wet grinding,
The mixing ratio of the flammable liquid and the raw material powder used for the wet pulverization is preferably adjusted so as to be the same as the content ratio of the flammable liquid and the raw material in the slurry used for spray combustion. If the amount of the liquid is adjusted so that the mixing ratio of the flammable liquid and the raw material during wet grinding and the content ratio of the flammable liquid and the raw material in the slurry become the same, the manufacturing process is simplified. preferable. In the present invention, the liquid used in the wet grinding and the flammable liquid used to prepare the slurry may be different,
Then, when the raw material is wet-pulverized using a liquid different from the flammable liquid, the pulverized material must be dried once, which is disadvantageous in the process.

As the wet pulverizer to be used, a medium agitation type mill typified by a bead mill is preferable because it is easily pulverized. However, in the present invention, the wet pulverizer is not limited to the medium stirring type mill, but may be another wet pulverizer. In order to reduce the contamination of the slurry by the material of the crushing container in the crusher, it is preferable to select alumina, zirconia or a composite ceramic of alumina and zirconia as the material of the liquid contact portion. Further, the material of the liquid contact portion in the crushing container may be quartz, which does not interfere with abrasion powder.

If the slurry thus prepared does not have a predetermined concentration, the slurry is adjusted to have a predetermined concentration by adding or diluting or concentrating a deficient flammable liquid. If the concentration of the solids in the slurry is too low, the productivity and economic efficiency decrease.If the concentration is too high, the viscosity increases, making it difficult to form droplets with a small diameter, and a fine spherical glass with a uniform particle size distribution. Is difficult to manufacture.

The concentration of the raw material in the slurry is usually 1 to 50% by weight, preferably 5 to 40% by weight, particularly preferably 10% by weight.
-40% by weight. If the concentration of the raw material in the slurry is too low, the productivity and economic efficiency will be reduced.If the concentration is too high, the viscosity of the slurry will increase and it may be difficult to perform spray combustion. It may be difficult to produce uniform microspherical glass.

For dispersing and stabilizing the slurry, a dispersant and a dispersion stabilizer may be added. As the dispersant, a nonionic surfactant, a cationic surfactant, an anionic surfactant, a polymer surfactant, or the like can be used.

Of these, high molecular weight anionic surfactants are preferred, for example, a copolymer of acrylic acid and acrylic acid ester having an acid value of 5 to 100 mg KOH /
An acid-containing oligomer such as an acid-containing acrylic oligomer having an acid value as large as about g is preferable. Such a polymer anionic surfactant contributes to the dispersion and dispersion stabilization of the slurry, and can advantageously suppress the viscosity of the slurry to a low level.

(Spraying / Combustion Step) In the method of the present invention, the slurry thus prepared is sprayed in the form of droplets,
The slurry in the form of droplets is burned.

As a method of spraying, a spray atomizer such as a liquid column type or liquid film type two-fluid nozzle, an ultrasonic atomizer, a rotating disk atomizer, or the like can be used, and mass production is easy. Thus, a two-fluid nozzle is preferred.

When a spray atomizer, particularly a sprayer having a two-fluid nozzle, is used, it is necessary to appropriately adjust the slurry discharge nozzle for spraying the slurry so that the droplets formed by spraying the slurry become minute. preferable. For example, it is preferable to set the diameter of the opening at the tip of the slurry discharge nozzle for spraying the slurry to 1 to 10 mm. In order to make the slurry into a spray state, the flow rate of gas passing through the tip of the slurry discharge nozzle is
Usually, it is preferably 0.01 m / sec or more, particularly preferably 0.1 to 10 m / sec. If the diameter of the tip opening of the slurry discharge nozzle and the flow rate are outside the above ranges, for example, 30
A nonporous body having an average particle size larger than μm may be formed.

The gas may be a non-combustible gas such as carbon dioxide gas, nitrogen gas, or combustion exhaust gas so as to eject slurry droplets from the slurry discharge nozzle.
In such a case, a combustion control gas for controlling the combustion is supplied to the slurry sprayed in a droplet form with the non-flammable gas, or the non-flammable gas is used in the atmosphere of the combustion control gas for controlling the combustion. It is desirable to spray the slurry in droplet form.

Examples of the combustion control gas include oxygen gas, air, and an oxygen-generating gas which decomposes by heating to generate oxygen. At this time, for example, when the particle size is 30
In order to produce a micro-spherical glass having a size of not more than μm, the oxygen concentration is 20 to 100% by volume, preferably 25 to 90% by volume.
It is good to adopt the combustion control gas adjusted to the following. If the oxygen concentration is less than 20% by volume, even if the combustible liquid in the slurry burns, the solid content in the slurry may not be sufficiently melted or sintered. The preferred value of the oxygen concentration is specifically, together with these factors, because the oxygen concentration affects the combustion temperature, and the combustion temperature of the slurry is affected by the type and amount of the flammable liquid in the slurry.
And it is determined appropriately.

Apart from the above, according to the present invention, as a gas for bringing the slurry into a spray state, a mixed gas of a nonflammable gas and a flammable gas, a mixed gas of the nonflammable gas and an oxygen-containing gas, A mixed gas of a nonflammable gas, a flammable gas, and an oxygen-containing gas may be used. However,
When a flammable gas is used as a gas for bringing the slurry into a spray state, the slurry is sprayed with the flammable gas in an oxygen-rich atmosphere and then burned, which may not be appropriate.

Examples of the flammable gas include LPG, natural gas, acetylene gas, propane gas, city gas and the like, and examples of the oxygen-containing gas include air and oxygen gas.

The content ratio of the flammable gas in the mixed gas of the nonflammable gas and the flammable gas is 1 to 90% by volume,
The content ratio of the oxygen-containing gas in the mixed gas of the nonflammable gas and the oxygen-containing gas is 1 to 90% by volume, and the content ratio of the combustible gas in the mixed gas of the nonflammable gas, the combustible gas, and the oxygen-containing gas Is 1 to 50% by volume, and the content ratio of the oxygen-containing gas is 1 to 50% by volume.

In the method of the present invention, the sprayed slurry is burned by a suitable ignition means.

Examples of the ignition means include a pilot burner, an electric spark ignition device using a glowing nichrome wire, for example, a piezoelectric element or the like.

The combustion temperature at which the slurry in the atomized state is burned depends on the temperature at which the solid material in the slurry is melted or sintered and the residence time,
Specifically, the temperature is usually 500 to 2500 ° C., preferably 5 ° C.
The range is from 00 to 2,000 ° C. In order to achieve such a combustion temperature and produce even higher quality microspherical glass, the type and amount of flammable liquid, the type and amount of combustion control gas, and the concentration of oxygen gas in oxygen-containing gas are adjusted. However, it is also preferable to spray the slurry toward a heating furnace such as an electric furnace and burn the slurry in the spray state in a heating furnace that is supplementarily heated.

In the method of the present invention, the microspherical glass is formed by bringing the slurry into a spray state and then burning the slurry droplets in the spray state.
In order to form non-porous and solid glass beads having a more uniform particle size and a smoother surface, it is preferable to adjust the spraying and combustion conditions optimally. Considering the aspect of spraying and burning in the method of the present invention, for example, slurry is ejected in the form of droplets from a slurry discharge nozzle, and slurry droplets fly in space for a predetermined time or a predetermined flight distance from the slurry discharge nozzle, When staying in the space, droplets of a predetermined particle size are formed, and then the sprayed slurry having the droplets burns, and during this combustion, the flammable liquid in the droplets becomes flammable gas or It is thought that the fuel burns with the help of oxygen gas and the heat of combustion causes the liquid components in the droplets to burn or evaporate, and at the same time, the raw materials in the droplets melt to form true spheres or near-spherical molten particles. . Then, while the molten particles pass through the combustion zone, the molten particles are cooled and solidified, and in some cases, extremely small molten particles are considered to be united and sintered.

In the method of the present invention, a slurry obtained by dispersing a raw material powder in a flammable liquid is spray-combusted to obtain a spherical particle having a particle size of 30 μm or less, particularly 20 μm or less, a smooth surface, High quality solid glass beads can be produced. More than this, the purpose is to form glass beads that are closer to a true sphere, smaller in particle diameter, and even and uniform in average particle diameter, with a smooth surface, nonporous and solid glass beads. When doing so, in addition to the above-mentioned preferred conditions, it is also preferable to arrange the inlet for the combustion control gas 2 to 10 cm in front of the slurry discharge nozzle. In other words, the flow velocity of the gas for spraying the slurry, in other words, the linear velocity of the slurry droplet ejected from the tip of the slurry discharge nozzle is 0.01 m / sec or more, especially 0.1 to 10 m / sec.
It is preferred that the droplets of the slurry be blown for a predetermined distance in seconds and then burned in an atmosphere containing oxygen gas. From another viewpoint, the droplet of the slurry ejected from the slurry discharge nozzle is kept as a droplet for about 0.05 to 1 second as the time from the ejection of the slurry discharge nozzle to the time of combustion. Is also preferred.

In order to adjust the average particle size of the fine spherical glass to be produced in the method of the present invention, the gas flow rate and the flow rate of the spray gas are controlled by controlling the flow rate of the slurry and the flow rate of the spray gas. May be optimized depending on the shape of the object.

The fine spherical glass formed as described above is collected by a known method such as a collecting method using a bag filter or a wet packed bed.

According to the method of the present invention, it is possible to produce micro-spherical glass having a uniform average particle size. However, in some cases, micro-spherical glass having a wide particle size distribution may be produced. In order to obtain a fine spherical glass of 30 to 0.5 μm or 20 to 0.5 μm, it is preferable to perform an appropriate classification operation. In the method of the present invention,
Glass beads having a particle size other than the desired particle size generated in the classification step can be recycled and used as a raw material in the method of the present invention. The ability to recycle the microspherical glass by-produced after classification as a raw material,
The method of the present invention is also a remarkable technical matter showing superiority to the conventional method for producing silica-titania glass by drying and firing a mixed gel of silica sol and titania sol.

(Microspherical Glass) As described above, microspherical glass is produced by the method of the present invention.

The fine spherical glass obtained by the method of the present invention contains 70 to 98% by weight, preferably 85% by weight of SiO _2.
98 wt%, B ₂ O ₃ 0 to 15 wt%, preferably 2-10 wt%, alkali metal oxides and total 0-5% by weight of alkaline earth metal oxides, preferably 0-3 weight %, Other metal oxides are 0 to 30% by weight, preferably 0 to 15% by weight, and the silicate glass is prepared so that the total of the above components becomes 100% by weight.

Examples of the alkali metal oxide include lithium oxide, sodium oxide, and potassium oxide. Examples of the alkaline earth metal oxide include calcium oxide, magnesium oxide, and barium oxide. Can be. Other metal oxides include:
Examples include zinc oxide, alumina, zirconia, titanium dioxide, and lead oxide.

If the total of the alkali metal oxide and the alkaline earth metal oxide exceeds 5% by weight, when the fine spherical glass is blended with a resin, the alkali glass is mixed under severe conditions in which an acid component is blended at the same time. The components elute and degrade the resin. Less than 70% by weight of SiO ₂ or B
_{If the} content of ₂ O ₃ exceeds 15% by weight, the amount of alkali eluted is undesirably increased. If the content of SiO ₂ exceeds 98% by weight, a high temperature is required for vitrification, and undesirably high costs are required for refractory facilities and the like in industrial production.

The microspherical glass of the present invention produced by the method of the present invention usually has an average particle size of 50 μm or less, particularly 30 μm or less, and more preferably 20 μm or less.

The microspherical glass is a solid glass bead having a smooth surface, no holes (non-porous), and no holes.

The microspherical glass produced by the method of the present invention is generally suitable as a filler. For example,
When the microsphere glass obtained by the method of the present invention is filled into a resin, the shape is microsphere, so that a molded article molded from this resin composition is less warped or deformed, and the surface of the molded article itself is smooth. And is suitable as a filler for a resin composition for molding into a molded article such as a housing or a substrate of precision equipment. Further, since the content of the alkali metal oxide and / or the alkaline earth metal oxide coexisting with the silica in the raw material is small, the deterioration of the composite resin composition of the microspherical glass and the resin with time due to the alkali component is small. . In addition, the microspherical glass produced by the method of the present invention has good slipperiness and a small amount of adsorbing fats and oils, and thus is suitable for blending into cosmetics.

[0049]

【Example】

Example 1 100 g of silica gel having an average particle size of 50 μm, 9.5 g of boric acid having an average particle size of 25 μm, and an acid value of 15 mg KOH
/ G of acid-containing acrylic oligomer of 11 g / kerosene
g, and then wet-pulverized using a bead mill to obtain a slurry of the raw material. The used bead mill is
The inner volume is 1,400 ml, and the material of the liquid contact part is zirconia. The beads are made of zirconia having an average diameter of 0.65 mmφ. 1,120 ml of the beads were used in a bead mill. The operation conditions of the bead mill were as follows: the number of revolutions was 2,500 rpm, and the grinding time was 30 minutes.

The powder was recovered from the obtained slurry of the raw material, and observed with a scanning electron microscope. As a result, the average particle size was about 0.2 μm.

This slurry was loaded into a two-fluid nozzle,
The slurry was sprayed by spraying carbon dioxide gas as a spray gas at a flow rate of 1 m / sec from a two-fluid nozzle. An oxygen-containing gas consisting of 80% by volume of oxygen and 20% by volume of nitrogen is introduced at a position 5 cm away from the tip of the two-fluid nozzle,
By bringing the flame closer, the slurry in the spray state was ignited and burned. The combustion temperature at this time is 1,800 ° C
Met.

The generated fine particles were collected by a bag filter.

The elemental analysis by wet analysis showed that SiO ₂
Was 95% by weight and B ₂ O ₃ was 5% by weight. The average particle diameter measured by the laser light scattering method was 3 μm,
The particle size of m or less was 97%. As a result of observation with a scanning electron microscope and X-ray diffraction measurement, the particles were spherical and amorphous. The specific gravity measured by the gas displacement method proved to be nonporous.

Example 2 82 g of silica gel having an average particle size of 50 μm, 25 g of boric acid having an average particle size of 25 μm, and an average particle size of 1
Example 1 was repeated except that 2 g of alumina of 0 μm, 5.5 g of sodium carbonate having an average particle diameter of 30 μm, and 11 g of an acid-containing acrylic oligomer having an acid value of 25 mgKOH / g were used.

The obtained powder was analyzed by elemental analysis using ion chromatography to obtain SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , and Na ₂ O.
Was 82% by weight, 13% by weight, 2% by weight, and 3% by weight, respectively. The average particle diameter measured by a laser light scattering method is 5 μm, and particles having a particle diameter of 20 μm or less are 95%
Met. As a result of observation with a scanning electron microscope and X-ray diffraction measurement, the particles were spherical and amorphous. The specific gravity measured by the gas displacement method revealed that the sample was nonporous.

[0056]

According to the present invention, solid microspheres having a fine, smooth surface, nonporous, and high chemical durability, which were conventionally difficult to produce industrially in large quantities and at low cost. A method can be provided in which glass can be manufactured in a small number of steps.

According to the present invention, the surface is smooth and non-porous, and gives a good feeling of use when used in cosmetics.
When used as a resin filler, it is possible to provide a microspherical glass having good dispersibility and filling property in a matrix resin and less elution of an alkali component.

Claims (2)

[Claims] 1. A method according to claim 1, wherein the content of SiO ₂ is 70 to 98% by weight and the content of B ₂ O ₃
Is 0 to 15% by weight, the total amount of alkali metal oxides and alkaline earth metal oxides is 0 to 5% by weight, the other metal oxides is 0 to 30% by weight, and the total of the components is 100% by weight. A microspherical glass, which is a silicate glass prepared as follows. _2. 70 to 98% by weight of SiO ₂ , B ₂ O ₃
Is 0 to 15% by weight, the total amount of alkali metal oxides and alkaline earth metal oxides is 0 to 5% by weight, the other metal oxides is 0 to 30% by weight, and the total of the components is 100% by weight. A slurry obtained by dispersing a silicate glass powder or a raw material mixed powder necessary for producing the silicate glass in a flammable liquid, so as to form droplets,
2. The method for producing microspherical glass according to claim 1, wherein the droplet-shaped slurry is burned and melted.