JPH0143690B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for manufacturing glass hollow spheres. More specifically, the present invention relates to a method and apparatus for manufacturing hollow spheres that can continuously and uniformly obtain thin-walled glass hollow spheres of any spherical diameter.

Conventionally, various methods for manufacturing hollow spheres have been proposed, particularly in the field of micro hollow spheres.
A method in which a spherical shell is formed by injecting and blowing a high-speed gas into a flow of a melt; a method in which a volatile component or a foaming agent is added and then heated to form a spherical shell;
A method is known in which a core material is used and the core material is later removed.

The present invention provides a novel method for manufacturing hollow spheres that is completely different from these conventional methods. The inventors of this invention came up with the idea of producing a glass hollow sphere by blowing gas into a glass melt to expand it into a balloon shape, and tried various experiments. First, as shown in Fig. 1, a glass melt 1 is suspended in a tube shape from an annular opening 7, and gas 2 is blown into the tube as shown by the arrow to form a balloon-shaped melt 3. The hollow spheres 6 were produced by blowing the air stream 5 into pieces to shred the melt 3 under various conditions.
However, in this method, although glass hollow spheres can be obtained, there is a risk that the molten body 3 will be shaken by the turbulence of the airflow 5 and the diameter and shape of the hollow spheres will become unstable, and the number of glass hollow spheres generated is also relatively small. Further, there is a problem in that the diameter of the hollow sphere is always larger than the annular opening 7, which hinders the degree of freedom in design.

As a result of further study and research, the inventors of the present invention found that by guiding the airflow to an orifice and further expanding and cutting the molten material through this orifice, a glass hollow sphere with a uniform diameter can be produced. This invention was achieved by discovering the fact that a large number of can be produced continuously.

Thus, according to the present invention, by blowing gas into the glass melt to expand it into a balloon shape and bring it close to the orifice, and by supplying an airflow that passes through the orifice along the outer periphery of the melt, the balloon-shaped melt is formed. Provided is a method for producing a glass hollow sphere, which comprises blowing out a part of the glass from an orifice and cutting it into hollow spheres, which are then solidified.

Hereinafter, the method of the present invention will be explained by giving specific examples with reference to the accompanying drawings. FIG. 2 is a diagram corresponding to FIG. 1 for explaining the method of the present invention. In the figure, a glass melt 1 is suspended like a bag from an annular opening 7, and gas 2 is blown into it to expand it into a balloon shape and bring it close to an orifice 4. At the same time, by supplying an air flow 5 that passes through the orifice 4 along the outer circumference of the balloon-shaped melt 3, a part 3' of the melt bulges out from the orifice 4 and is cut into pieces to obtain a hollow spherical melt. A desired glass hollow sphere 6 is produced by cooling and solidifying. Then, by continuously supplying the melt 1, the gas 2, and the air flow 5, the glass hollow spheres 6 are continuously obtained.

The glass melt in this invention may be any glass melt having a viscosity that allows it to expand into a balloon shape when gas is blown into it, and its viscosity is usually 300 to 5000 cP, preferably 500 to 2000 cP. In addition, various glass materials known in the art may be used as the glass material. According to the method of the present invention, various hollow spheres can be obtained by using a melt having an appropriate viscosity regardless of the glass composition.

On the other hand, as the gas for expanding the melt used in this invention and the air flow flowing out to the orifice, air is usually convenient, and an inert gas may also be used. It is generally preferred that such gases and air streams be heated so as to prevent the melt from solidifying or increasing its viscosity upon cooling.

According to the method of this invention, thin wall (usually thick
5μm to 500μm) and uniform ball diameter (usually 1mm to 15mm)
Continuously large number of hollow spheres (several tens to thousands of spheres/second)
Can be manufactured. The diameter of the orifice depends on the size of the balloon-shaped melt, but usually the diameter is 1 to 1.
It is appropriate to use pores of 10 mm. Usually, a hollow sphere with a diameter of hollow sphere/orifice diameter of 0.4 to 1.4 is obtained.

According to another aspect of the invention, a manufacturing apparatus suitable for the method for manufacturing hollow spheres described above is provided. That is, a melting furnace equipped with a heating means, a melt expansion tube having an annular opening capable of suspending a glass melt from the melting furnace in a bag shape, and having a gas supply port for expanding the melt inside, A melt shredding orifice located below the expansion tube and coaxial with the annular mouth of the expansion tube, and an air flow flowing out to the orifice along the outer circumference of the glass melt expanding from the expansion tube. Provided is an apparatus for manufacturing a glass hollow sphere, comprising a molding space that constitutes a flow path.

A specific example of the manufacturing apparatus of the present invention will be explained with reference to FIG. In the figure, reference numeral 9 indicates an electric furnace, in which there is a melting tank 8, in which a glass melt 4 having a viscosity of 500 to 2000 cP, which has been melted by the electric furnace, is stored. The melting tank 8 has a gas supply pipe 2a, and the bottom of the melting tank has a V-shape and is configured to function as a valve so that molten glass can be supplied at a desired flow rate.

The gas supply pipe tip 2b has an inner diameter of 2 mm and an outer diameter of 5 mm, and is located concentrically with the melting tank tip 8a (inner diameter 7 mm), and the glass melt is suspended in a bag shape from the annular opening 7 of the space, and the gas supply pipe A bulging melt 3 is obtained by the gas 2 from 2a. An orifice 4 with a diameter of 5 mm is provided below the nozzle 8a and is located coaxially with the gas supply pipe tip 2b. The airflow 5 that cuts the expanding melt 3 at the orifice is supplied from the air flow supply pipe 5a, flows along the outer periphery of the expanding melt 3, and passes through the orifice 4. that time,
The melt is shredded and a hollow spherical melt 6 is discharged. Note that 10 is an electric furnace for preventing the temperature of the four orifices from decreasing.

Further, according to the above-mentioned apparatus, by adjusting the inner diameter and outer diameter of the annular opening 7 and adjusting the orifice diameter, hollow spheres with various wall thicknesses and spherical diameters can be manufactured, and the molten material can be supplied with various thicknesses and diameters. These can also be controlled by appropriately changing the supply amount of each gas. For example, the orifice diameter and annular mouth inner diameter are 3.
mm and the melt supply rate is 1.68 g/min (viscosity 900~
1100cP), the gas flow rate A from the gas supply device is approximately 2 to 20 ml/sec, and the gas flow rate B from the air flow supply device is approximately 20 to 130 ml/sec. are less than this,
Many hollow spheres adhere to the orifice outlet, which is inappropriate. In addition, when the gas flow rate A exceeds 20 ml/sec, non-periodic intermittent occurrence occurs when the gas flow rate B is in the range of 20 to 80 ml/sec, and even beyond that, the bulging part from the orifice becomes atomized. It is unsuitable because a hollow sphere cannot be obtained. Further, even if the gas flow rate A is within the above range, if the gas flow rate B exceeds the above range, atomization will still occur from the orifice outlet, making it impossible to obtain hollow spheres, which is inappropriate.

However, the conditions for the gas supply amount vary depending on the melt supply amount, orifice diameter, etc., and therefore are not particularly limited to the above range. Normally, when the flow rate A of the gas for expanding the melt is 1, it is appropriate that the flow rate B of the air flow is 20 to 100.

Due to its uniformity and lightness, the glass hollow spheres obtained in this way can be used as fillers for various plastics, lightweight aggregates for composite structural cement, small floats, heat insulating materials, dielectric materials, adsorbent carriers, and microcapsules. It can be applied to other uses.

As understood from the above description, the manufacturing method and manufacturing apparatus of the present invention can continuously manufacture a large number of various glass hollow spheres, and are found to be useful for various uses.

Hereinafter, hollow spheres obtained by the present invention will be explained with reference to Examples.

Example 1 Waste bottle glass was placed in a melting tank and heated in an electric furnace.
A glass melt heated to 1500° C. and set to have a viscosity of 3000 cP was made into a hollow sphere using the apparatus shown in FIG. 3 under the following conditions.

Molten glass supply rate: 12 g/min Gas blowing rate: 10 c.c./sec Air flow supply rate: 60 c.c./sec Orifice diameter: 4 mm At this time, the number of hollow spheres generated is 60/sec. The properties of the hollow spheres obtained are as follows: It was 4 to 4.5 mm, and the film thickness was about 15 μm.

Example 2 Low melting point glass was placed in a melting tank and heated at 800 °C in an electric furnace.
℃, the viscosity was set to 800 cP, and hollow spheres were produced in the same manner as in the example. At this time, the number of hollow spheres generated was 110/second, the diameter was 2.5 to 3.0 mm, and the film thickness was 8 μm.

[Brief explanation of drawings]

FIG. 1 is a configuration explanatory diagram including a cross section for comparatively explaining the manufacturing method of the present invention, FIG. 2 is a configuration explanatory diagram including a cross section illustrating the manufacturing method of the present invention, and FIG. FIG. 2 is a configuration explanatory diagram including a cross section showing an example of the device. 1... Glass melt, 2... Gas, 3... Balloon-shaped melt, 4... Orifice, 5... Air flow, 6
... Glass hollow sphere, 7 ... Annular mouth, 8 ... Melting tank, 9 ... Electric furnace.

Claims (1)

[Scope of Claims] 1. A balloon-shaped molten body is created by blowing gas into the glass molten body to expand it into a balloon shape and bringing it close to an orifice, and supplying an air flow that passes through the orifice along the outer periphery of the molten body. A method for manufacturing a glass hollow sphere, which comprises: expanding a part of the glass from an orifice and cutting it into hollow spheres, and solidifying the hollow spheres. 2. A melting furnace equipped with a heating means, a melt expansion tube having an annular opening capable of suspending the glass melt from the melting furnace in a bag shape, and having a gas supply port for expanding the melt inside, A melt shredding orifice located below the expansion tube and coaxial with the annular mouth of the expansion tube, and an air flow flowing out to the orifice along the outer circumference of the glass melt expanding from the expansion tube. A manufacturing device for a glass hollow sphere, comprising a molding space that constitutes a flow path.