JPS5930656B2 - Manufacturing method of micro glass spheres - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing micro/J% glass spheres used for passage signs, reflective sheets for automobile license plates, and the like.

Conventionally, the method for manufacturing this type of fine glass spheres is to first melt the glass, then drain the glass melt into a water tank and rapidly cool it to produce coarse particles called granulated cullet. Further, the coarse particles are pulverized by a pulverizer and sieved to form desired fine particles.

Next, these fine particles are passed through a high-temperature flame of a forming furnace to be reheated and molten, and surface tension is applied to the particles to form them into spheres, and finally they are cooled to form glass spheres.

Also known is a method of melting glass, blowing high-pressure air onto the melt to form a fine melt, applying surface tension to the melt, spheroidizing it, and cooling it to form glass spheres.

However, glass bulbs used for this type of purpose must be uniform, e.g.
It is necessary to have a particle size distribution of about 0 microns.

That is, if there is a large difference in particle size distribution, the thickness of the resin layer coated thereon will also be non-uniform, resulting in a decrease in retroreflectivity.

However, depending on the method described above, it is extremely difficult to obtain glass spheres with small particle sizes uniformly and in good yield.
Improvement of this was requested.

The present invention was made based on the above-mentioned needs, and after granulating unnecessary fine particles generated in the crushing process or molding process using a granulator to obtain a desired particle size, the particles are heated in a high-temperature flame as in the past. An object of the present invention is to provide a method for producing microscopic glass spheres, which can be formed into a spherical shape as a homogeneous molten liquid to obtain glass spheres with a uniform microscopic particle size in a high yield and at low cost.

That is, for example, a glass material of a predetermined composition is melted in a tank furnace or a pot furnace, and the melt is flowed into a water tank to create granulated current. After drying, this cullet is crushed in a crusher and sieved to obtain a desired particle size. obtain fine particles with less
Further, the fine particles are put into a granulating device and granulated.

In this granulation process, several to hundreds of fine particles aggregate to form one granule.

Then, the granules are sieved to extract only granules having a desired particle size.

That is, the large-diameter particles remaining on the sieve are re-pulverized, followed by granulation with particles of smaller particle size, and the particles with the required particle size are selected.

By repeating this operation, all the fine particles are finally granulated to a desired particle size.

When the granulated powder thus produced is heated in a high-temperature flame as in the conventional method, the fine particles that are in close contact with each other in the granulated powder are fused together to form a homogeneous molten liquid.

Therefore, this molten liquid becomes spherical due to the action of surface tension, and transparent microscopic glass spheres are obtained by rapid cooling.

Next, examples of the present invention will be described.

Example 1 Glass composition 1, lead oxide (PbO) 50% (weight) 2, titanium oxide (Ti02) 30 tt tt3, barium oxide (Bad) 20 u u Melt diameter water at 1.400°C with the above composition. After being crushed to produce coarse particles with a diameter of about 500 microns and dried, the particles are crushed into 200 mesh or less using a ball mill and sieved through a 250 mesh (74 micron) sieve to take out particles of 200 to 250 mesh.

The fine particles having a mesh size of 250 or less are then placed in a fluidized granulator to be described later and granulated to a maximum particle size of 74 to 88 microns.

Moreover, the particles thus obtained are 200 to 25
Sift through a 0-mesh sieve and remove.

Incidentally, the coarse particles having a mesh size of 200 or more are crushed again using a pulverizer, and together with the fine particles having a mesh size of 250 meshes or less, they are again granulated using a granulator to obtain a particle size of 74 to 88 microns.

This process is repeated several times by Kokichi, and the total amount of fine particles of 250 mesh or less generated by the crushing is made into particles of 74 to 88 microns.
It was possible to obtain glass spheres with the desired particle size by molding them together with micron particles in a molding furnace.

The fluidized granulation device has a main body 1 formed in the shape of a dome-shaped container, a wire mesh 2 of 400 mesh arranged at the bottom of the main body, a binder liquid injection nozzle 3 located at the top of the main body, and a wire mesh 2. A hot air blowing device 4 located below is provided, and water containing, for example, 1 to 2% of cellulose adhesive is injected from the spray nozzle 3, and the hot air 4 blows onto the fine particles 5 in a suspended state to bond them together. This is referred to as particle formation 5'.

6 is a hot air generator, and 7 is a collecting device.

Example 2 Glass composition 1, lead oxide (PbO) 50% (weight) 2, barium oxide (Bad) 40% 〃3, silicon oxide (510%)
2) Section 10 After melting the material with the above composition at 1.450°C, blow high-pressure air onto the melt to blow it away and cool it to form coarse glass spheres of 100 to 1.000 microns. was pulverized to 300 mesh or less using a ball mill.

Then, as in Example 1, the entire amount was made into particles of 74 to 88 microns using a granulating device, passed through a forming furnace, and fusion-molded to obtain glass spheres with a desired particle size.

As described in detail above, the present invention applies granulation treatment to glass particles having a diameter of 1/2 inch or more than a desired particle size to form granules, which are then subjected to high temperature treatment and fusion molding to obtain a uniform desired particle size. Since this is a manufacturing method of micro glass spheres with glass spheres having This has the advantage that the yield can be significantly improved and the cost can be reduced because it can be made into microscopic glass spheres.

[Brief explanation of drawings]

The figure is a schematic explanatory diagram of a granulation device showing one embodiment of the present invention. 5... Fine particles, 5'... Particle formation.

Claims (1)

[Claims] 1. A step of generating fine particles with a diameter smaller than a desired particle size from a glass melt, and a step in which the fine particles are introduced into a fluidized nucleation device that spouts hot air from the lower side and binder from the upper side, and the entire amount is subjected to granulation treatment. 1. A method for producing microscopic glass spheres, comprising the steps of: forming particles by fusion molding the particles, and forming glass spheres having a desired particle size after fusion-molding the particles.