JPS6140827A - Preparation of porous glass plate - Google Patents

Abstract

PURPOSE:To prepare a porous glass plate having uniform bulk density easily by allowing raw material for forming glass to react in flame, prepg. a porous glass body by depositing generated fine glass particles on a base plate, and cutting to sheets after sintering. CONSTITUTION:A raw material for forming glass such as SiCl4, H2 and O2 as combustion gas are fed to a synthesizing burner 1, and flame hydrolysis reaction is caused in the flame 2, and generated fine glass particles 3 are deposited on a flat base plate 4. Obtd. porous glass body 5A is heated uniformly with a heatig device 6 and sintered to the degree that each fine glass particle 3 welds to each other firmly but the voids between the fine particles are not buried completely. Then, obtd. block of the porous glass body 5B having uniform bulk density and pore size is cut to a specified thickness. Thus, an aimed porous glass plate 7 is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing porous glass sheets having uniform composition and bulk density.

[Prior art]

Vycor glass is conventionally known as a porous glass plate. Vycor glass is produced by melting and molding silicate glass using a conventional method, heat-treating this glass in the transition temperature range to separate it into a 1Ja20-B203-rich phase and a 5i02-rich phase, and then acid-treating it to form Na20. -B2O
This is a method in which the phase rich in 3' is gradually eluted, and the part rich in 5i02 is made into porous glass. There are problems in that it is limited to very special types and it is extremely difficult to control the pore diameter.

[Means to solve problems]

Glass fine particles obtained by hydrolyzing a glass forming raw material such as SiCl4 in a flame are deposited on a base material to create a porous glass body in the shape of a rod or block, which is then heated and sintered at a high temperature. The porous glass body is made into a porous glass body having a uniform bulk density, and then cut into a plate shape.

[For production]

A porous body formed by depositing glass particles on a base material is
There is local variation in bulk density due to the temperature distribution of the adhering surface during the adhesion and growth of fine particles, but by uniformly heating the entire glass particle at a high temperature, the surface layer of each individual glass fine particle melts. Adjacent fine particles are fused together.

By stopping the heating and sintering process described above before the glass particles are completely melted and the voids between the particles disappear, pores remain between adjacent glass particles, and these pores are uniform throughout. Since they exist in various sizes and densities, by cutting the sintered base material to an appropriate thickness, a porous glass plate with uniform bulk density can be obtained.

〔effect〕

According to the present invention, the voids created between the particles due to the accumulation of glass fine particles become voids in the porous glass plate, so that the voids of uniform size are uniformly distributed throughout the porous glass plate regardless of the size of the base material. A porous glass plate having a highly uniform bulk density can be obtained. Furthermore, the size of the pores can be varied over a very wide range simply by changing the temperature conditions of the heating and sintering process.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments shown in the drawings.

In Figure 1, 5 is used as a glass forming raw material in the synthesis burner/.
IfJ4 is supplied as combustion gas, and H2 and 02 are respectively supplied as combustion gas. The glass particles 3 made of 5i02 produced by the flame hydrolysis reaction in the burner l are deposited on the base material on the flat plate placed below the burner l.
A porous glass body jA is formed. The porous glass body SA obtained here has a bulk density that differs depending on the location because the temperature on the adhesion surface during deposition of the glass particles has a distribution.

Next, the entire porous glass body S is uniformly heated by a heating device B to sinter the glass particles to the extent that they are firmly fused together and the voids between the particles are not completely filled. The block-shaped porous glass body 5B obtained by the above sintering process has a uniform bulk density and pore diameter. By appropriately selecting the temperature during the above sintering process, a porous glass body can be created! The size of the pores in B can be controlled over a wide range.

Next, the porous glass body jB obtained by the sintering process is cut to a predetermined thickness, and if necessary, post-processing such as polishing is performed to obtain a porous glass plate 7. An example is shown below.

In this example, the glass particles 3 generated in the flame λ of the burner L are attached to the rod-shaped rotating starting substrate DA, and the substrate t or the burner 1 is moved in the axial direction of the base material G, so that the glass particles are almost completely removed. A porous glass body is deposited in a cylindrical shape.
to form. Next, by heating and sintering the entire columnar porous glass body jA in a heating device, a porous glass body sB having a uniform bulk density and pores is obtained.

A disc-shaped porous glass plate 7 can be obtained by cutting this porous glass body tB perpendicularly to the axis at a constant thickness. Such porous glass plates are made of high-purity quartz plates,
It is useful as a base material for glass plates, etc. Next, specific numerical examples will be explained.

When a 5i02 porous glass body was created using 5iOIIa as a raw material, the size of the fine particles immediately after synthesis was approximately 0.1 μm.
1 Bulk density is 0.3g/Cm near the center, approximately 0 at the periphery,
/ g/Cm", average o, rg7cm". As a result of heating and sintering this porous glass body at /300"C for about 20 minutes, it has a diameter of 70 mm, a length of 210 mm, a bulk density of o,
A porous glass rod having a uniform bulk density throughout the entire body was obtained with a particle size of sg/am''. When this porous glass body was observed with an electron microscope, the particle size was o, is ~ 0.2!; l
The size of the pores is O1g in 1m! , 0 μm, and could be easily cut into a plate shape. Moreover, as a result of heating and sintering the same unsintered porous glass body as above at 7600°C for about 30 minutes, the diameter was 3! ;mm, length/1)0mm
.

The true density of quartz glass (2,
A porous glass rod with a uniform bulk density of approximately 2 g/Cm') was obtained. The size of the pores in this porous rod is 0.1-0.3 μm, as described above. The pores were smaller and denser than those subjected to 00''C sintering treatment, and the cutting workability was similar to that of ordinary quartz glass.

As described above, it was confirmed that a porous glass body with pores of a target size can be easily obtained by controlling the sintering conditions.

[Brief explanation of the drawing]

Figures 1 (a), (b), and (c) are diagrams showing one embodiment of the present invention, and Figure 2 (a), (b), and ()→ show another embodiment of the present invention step by step. FIG. /...Burna! ...Flame 3...Glass particles q...Base material! ;A, SB・
... Porous glass body 6 ... Heating device 7 ... Porous glass plate Patent applicant Nippon Sheet Glass Co., Ltd. Agent Patent attorney Seiichi Ohno Figure 1 (a) (8) No. 2 (a) ( Eight)

Claims (2)

[Claims] (1) Glass fine particles obtained by reacting glass forming raw materials in a flame are deposited on a base material to create a porous glass body, which is then heated and sintered at high temperature to create a porous glass body with uniform bulk density. 1. A method for producing a porous glass plate, which comprises forming a porous glass body into a glass body and then cutting the porous glass plate into a plate shape. (2) A method for producing a porous glass plate according to claim 1, using SiCl_4 as a glass forming raw material.