JP2562788B2 - Method for producing fine hollow glass spheres - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a production method for producing hollow glass spheres from a volcanic glassy deposit such as shirasu as a raw material, and more specifically, to hydrophilicity of fine particle surfaces of volcanic glassy deposits. The present invention relates to a production method for producing fine hollow glass spheres from fine particles of a volcanic glassy deposit by using a hydrophilicity reducing agent.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 48-17645 has been proposed as a conventional method for producing fine hollow glass spheres, which are raw materials for various lightweight composite materials, from volcanic glass deposits such as shirasu. However, this method is 20 μm
When applied to the production of fine hollow glass spheres having the following particle diameters, the desired fine hollow glass spheres cannot be obtained. Therefore, a conventional technique for obtaining fine hollow glass spheres having a particle size of 20 μm or less has been proposed as Japanese Patent Laid-Open No. 2-296750, and its production method will be described below.

In this method, volcanic glass particles having a particle size adjusted to 20 μm or less are heat-treated in a hydrochloric acid or sulfuric acid solution for 8 hours or more, and then washed with water and dried.
Then, the dried particles are heat-treated at a temperature of 900 ° C. to 1100 ° C. for 1 second to 1 minute to obtain a fine hollow glass spherical body having a desired particle diameter.

[0004]

However, when the above-mentioned manufacturing method is used, it is possible to obtain fine hollow glass spheres having a particle size of 20 μm or less. Since a device for heat treatment with a solution and a device for washing and drying particles after treatment with an acid solution are required,
The manufacturing process has become complicated, making practical application difficult.

In order to avoid complication of this manufacturing process,
When a volcanic glassy deposit with a particle size of 20 μm or less is hollowed using a fluidized bed heating furnace, particles may be blocked in a pipe, or particles may fluctuate in transportation. It becomes difficult to constantly supply particles to the inside of the layer heating furnace. In addition, since the flow velocity in the fluidized bed heating furnace is relatively slow, the particles do not separate from each other when being supplied to the heating atmosphere, and it has been obtained experimental results that fused substances and unexpanded particles are easily generated.

The present invention was devised to solve the above problems, and an object thereof is to simplify the process before the supply of fine particles of volcanic glassy deposits to a fluidized bed heating furnace. At the same time, it is an object of the present invention to provide a method for producing fine hollow glass spheres capable of reducing the generation of fused substances and unfoamed substances.

[0007]

Means for Solving the Problems In order to solve the above problems, a method for producing fine hollow glass spheres of the present invention comprises fine particles of a volcanic glassy deposit and a hydrophilicity-reducing agent that reduces the hydrophilicity of the fine particles. The mixture is prepared by using a fluidized bed heating furnace to produce a mixture of 900 ° C to 120 ° C.
A method of heat treatment at 0 ° C. is used.

[0008]

[Function] Since the surface of the fine particles of the volcanic glassy deposits has active surface hydroxyl groups, the fine particles easily adsorb moisture in the air, and this property becomes stronger as the diameter of the fine particles becomes smaller.

On the other hand, the fine particles of the volcanic glassy deposit in a mixed state with the hydrophilicity-reducing agent have a small particle size because the hydrophilicity of the surface is reduced by the hydrophilicity-reducing agent. No strong cohesiveness. Therefore, no clogging or the like occurs in the transportation route to the fluidized bed heating furnace, so that the supply of fine particles to the fluidized bed heating furnace is maintained in a steady state. Further, since it does not exhibit strong cohesiveness, the fine particles are dispersed in particle units without agglomerating with each other in the fluidized bed heating furnace. In this state, the fine particles of the volcanic glassy deposit are heat-treated to form fine hollow glass spheres.

[0010]

EXAMPLES Examples of the present invention will be described below.

The first embodiment will be described.

In this example, as a volcanic glassy deposit which is a raw material, a secondary sedimentary shirasu (hereinafter simply referred to as shirasu) produced in Yoshida Town, Kagoshima Prefecture and having a relatively fine grain size is used. I am using. Further, the hydrophilicity-reducing agent is a coupling agent that imparts water repellency to the surface of the fine particles of Shirasu by causing a coupling reaction with the surface hydroxyl groups of the fine particles of Shirasu, and is a silane coupling agent containing methyltrimethoxysilane as a main component. The agent is used.

First, 0.2% by weight of a silane coupling agent is added to the raw material Shirasu. Then, by using a vibration mill, the shirasu to which the silane coupling agent is added is pulverized while being mixed with the silane coupling agent to obtain a powder of shirasu fine particles having an average particle diameter of 4.8 μm and the silane coupling agent. A mixture is formed.

After the mixture was dried at 200 ° C. for 3 hours, the angle of repose and the angle of collapse were measured and found to be 28 degrees and 12 degrees, respectively. That is, this mixture is a powder exhibiting good fluidity even though the average particle size of the fine particles is as extremely small as 4.8 μm.

Next, this mixture is heat-treated at 1000 ° C., which is a temperature in the range of 900 ° C. to 1200 ° C., by using a fluidized bed heating furnace, whereby fine particles of shirasu are converted into fine hollow glass spheres. To do.

In this heat treatment, the mixture is transported to the fluidized bed heating furnace without causing blockage in the transportation pipe. The fine hollow glass spheres obtained as a result of the heat treatment have an average particle size of 13.8μ.
m, and the compacted apparent density is 0.282 g / cm ^3, and it is a fine hollow glass sphere with very little generation of fused substances and unfoamed substances.

The second embodiment will be described.

For the volcanic glass deposits in this embodiment, the same shirasu as in the first embodiment is used. Further, in the hydrophilicity-reducing agent, the hydrophilic group faces the surface side of the fine particles of Shirasu, and the hydrophobic group faces the side corresponding to the hydrophilic group,
Oil is used to cover the surface of fine particles of Shirasu with a hydrophobic group. Specifically, this oil is a silicone oil containing dimethylpolysiloxane as a main component and having a viscosity of 100 centipoise.

First, 0.2% by weight of silicone oil is added to Shirasu. Then, the shirasu to which the silicon oil is added is pulverized while being mixed by using a vibration mill to produce a mixture in which the average particle diameter of the shirasu fine particles is 4.1 μm.

After the mixture was dried at 200 ° C. for 3 hours, the angle of repose and the angle of collapse were measured to find that the angles were 25 ° and 14 °, respectively. Despite having an extremely small particle size of 4.1 μm, the powder has good fluidity.

Then, this mixture is subjected to heat treatment at 1000 ° C. by using a fluidized bed type heating furnace, whereby fine particles of Shirasu are made into fine hollow glass spheres.

Also in this heat treatment, as in the first embodiment, the mixture was transported without causing blockage in the piping for transportation, and the characteristics of the resulting fine hollow glass spheres were as follows: The average particle size is 12.1 μm, and the apparent density is 0.272 g / cm ³ . In other words, it is a fine hollow glass sphere with very little generation of fused substances and unfoamed substances.

The third embodiment will be described.

For the raw material volcanic glass deposit used in this example, the same shirasu as in the first and second examples was used. Further, the hydrophilicity-reducing agent is a resin agent that covers the surface of fine particles of shirasu with a resin, and a silicone coating agent containing silicone resin as a main component is used.

First, 0.5% by weight of the silicone coating agent was added to the shirasu, and the shirasu to which the silicone coating agent was added was pulverized while being mixed by using a vibration mill to obtain an average particle size of 4. It produces a mixture of 2 μm.

After the mixture was dried at 200 ° C. for 3 hours, the angle of repose and the angle of collapse were measured, and the angles were 45 ° and 22 °, respectively. Is 4.2 μm, which is very small, but the powder has good fluidity.

Then, this mixture is heat-treated at 1000 ° C. by using a fluidized bed type heating furnace to hollow out the fine particles of Shirasu to form fine hollow glass spheres.

Also in this heat treatment, as in the first embodiment, the mixture was transported without causing blockage in the piping for transportation, and the characteristics of the fine hollow glass spheres obtained as a result were as follows: The average particle size is 15.2 μm, the compacted apparent density is 0.312 g / cm ³ , and it is a fine hollow glass sphere with very little generation of fused substances and unfoamed substances.

As described above, the average particle size of the fine particles of the volcanic glassy deposit is 20 such that the average particle size is 4 to 5 μm.
In the case of μm or less, the fluidity of the mixture of the volcanic glassy sediment and the hydrophilicity-reducing agent is remarkably improved, and the result is that the effect of reducing the generation of the fused substance and the unfoamed substance is extremely remarkable. Is getting

Regarding the ratio of the hydrophilicity-reducing agent to the volcanic vitreous deposit in the mixture, when the method of adding the hydrophilicity-reducing agent to the volcanic vitreous deposit and then pulverizing is adopted, the activity of the particles during pulverization is Since the surface reacts effectively with the hydrophilicity-reducing agent, it is necessary to obtain equivalent fluidity as compared to the case where the hydrophilicity-reducing agent is mixed with volcanic glassy deposits that have been ground to a predetermined particle size. The experimental result has shown that the amount of the hydrophilicity-reducing agent is 1/5 to 1/10.

Therefore, in the production of the mixture, when the method of pulverizing the volcanic glassy sediment to which the hydrophilicity-reducing agent is added is adopted, the amount of the hydrophilicity-reducing agent used is the smallest and the manufacturing cost is further reduced. The effect is that it becomes possible.

It should be noted that the present invention is not limited to the above-mentioned examples, and regarding the method for producing the mixture, after adding the hydrophilicity-reducing agent to the volcanic vitreous deposit, the volcanic vitreous deposit is crushed with a vibration mill. Although the method has been described, as another method, for example, a method of previously mixing the volcanic glassy deposit and the hydrophilicity-reducing agent and then crushing the mixture with a vibration mill or the like, or by using a jit mill or the like is used. It is possible to add a hydrophilicity-reducing agent during the pulverization of volcanic glassy deposits, or to add a hydrophilicity-reducing agent to volcanic glassy deposits that have been adjusted to a desired particle size range in advance. Is.

Regarding the ratio of the hydrophilicity-reducing agent to the volcanic glassy deposit in the mixture, the silane coupling agent was 0.2%, and the silicone oil was 0.2%.
%, The silicone coating agent has been described as 0.5%, but any ratio may be used as long as a good result can be obtained, depending on the method of forming the mixture or the kind of the hydrophilicity reducing agent. Is possible (obtained experimental results that the ratio giving good results is in the range of 0.1% to 2%).

Regarding the temperature of the heat treatment in the fluidized bed heating furnace, the case of 1000 ° C. has been described, but it is possible to set it to any temperature in the range of 900 ° C. to 1200 ° C. that can obtain good results. .

Although the case where the silane coupling agent is used as the coupling agent has been described, other coupling agents such as a titanate coupling agent can be used.

The hydrophilicity-reducing agent has been described as a coupling agent, a silicone oil, or a silicone coating agent, but other hydrophilicity-reducing agents may be used, such as an alkaline earth salt of stearic acid or N-. It can be an amino acid-based surface modifier such as lauroyl lysine or N-lauryl aspartic acid-β-lauryl ester.

Regarding the particle size of the volcanic glassy deposit in the mixture, the case where the particle size is 4 to 5 μm has been described, but the same applies to other particle sizes such as an average particle size of 20 μm or less. The present invention can be applied to the above, and also when the average particle diameter is 20 μm or more.

[0038]

The method for producing fine hollow glass spheres according to the present invention produces a mixture of a hydrophilicity-reducing agent for reducing the hydrophilicity of fine particles of volcanic glassy deposits and the fine particles, and the mixture thus produced. Is heat-treated at 900 ° C. to 1200 ° C. by using a fluidized bed heating furnace. Therefore, the fine particles of volcanic glassy deposits have reduced hydrophilicity on the surface by a hydrophilicity-reducing agent and do not show strong cohesiveness despite their small particle size. The supply route to the fluidized bed type heating furnace is maintained in a steady state. Further, in the fluidized bed type heating furnace, the fine particles are dispersed in particle units without agglomerating with each other. for that reason,
Before the fine particles of the volcanic glassy deposits are supplied to the fluidized bed heating furnace, it is possible to reduce the generation of fused substances and unfoamed substances even when the treatment of the fine particles is simplified.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Akira Nakashige 1445 Oda, Hayato-cho, Aira-gun, Kagoshima 1 Inside Kagoshima Industrial Technology Center (72) Inventor Tetsuro Kokusei 1445 Oda, Hayato-cho, Aira-gun, Kagoshima Prefecture 1 Kagoshima Industrial Technology Center (72) Inventor Ichiro Tabata 1445, Oda, Hayato-cho, Aira-gun, Kagoshima 1 Kagoshima Industrial Technology Center (56) Reference Japanese Patent Publication 4-32697 (JP, B2)

Claims (4)

(57) [Claims] 1. A mixture of fine particles of volcanic glassy deposits and a hydrophilicity-reducing agent that reduces the hydrophilicity of the fine particles is produced, and the mixture is heated at 900 ° C. to 1200 ° C. by using a fluidized bed heating furnace. A method for producing fine hollow glass spheres, which comprises heat treatment at ℃. 2. The method for producing fine hollow glass spheres according to claim 1, wherein the fine particles are particles having an average particle diameter of 20 μm or less. 3. The fine hollow glass spheres according to claim 1, wherein the mixture is produced by crushing the volcanic glassy deposit to which the hydrophilicity-reducing agent is added. Production method. 4. The coupling agent which imparts water repellency to the surface of the fine particles by causing a coupling reaction with a surface hydroxyl group of the fine particles, such as a silane coupling agent or a titanate coupling agent. , Or an oil such as silicone oil that covers the surface of the fine particles with a hydrophobic group, or a resin agent that covers the surface of the fine particles with a resin such as a silicone resin, or an alkaline earth salt of stearic acid that acts as a lubricant. Alternatively, it is an amino acid-based surface modifier, and the method for producing fine hollow glass spheres according to claim 1, 2 or 3.