JPS62171937A - Production of glass article - Google Patents

Abstract

PURPOSE:To obtain a glass rod or glass pipe free from bend, by depositing glass soot on surface of a column or cylinder of high-purity glass and clarifying the deposited glass soot under specific condition. CONSTITUTION:Glass soot is deposited on a surface of a first column or cylinder of a high-purity glass and is clarified in a high-temperature furnace to obtain the second column or cylinder. The heat-treatment is carried out under a condition to give a shrinkage of deposited glass soot of <=15% within a temperature range to give a glass viscosity of <=10<16> poise and >=10<9> poise. The heat- treatment is preferably carried out by using a soaking pit as the high- temperature furnace and raising the temperature of the furnace at a rate of >=2 deg.C/min on an average between a temperature range to give a glass viscosity of <=10<16> poise and >=10<9> poise (between standby temperature and clarification temperature).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing glass articles, and more specifically, the present invention relates to a method for manufacturing glass articles, and more specifically, the present invention relates to a method for manufacturing glass articles, and more specifically, the present invention relates to a method for manufacturing a glass article, and more specifically, the present invention relates to a method for manufacturing a glass article. A method for preventing bending of the cylinder or cylindrical body that occurs when the glass particles become transparent, in a method of manufacturing a new cylinder or cylinder by inserting the laminated glass particles into a high-temperature furnace and making them transparent. It is related to. The cylindrical or cylindrical tubular glass article of high purity glass produced according to the present invention can be suitably used as a base material for optical fiber.

[Prior art] A method for transparently vitrifying a laminate of glass particles obtained by flame hydrolysis of glass raw materials is to hold it in a high-temperature furnace, or to sequentially make it transparent by moving the heating zone in the high-temperature furnace. There is a way to go. In the first method, an apparatus (soaking furnace) as shown in FIG. 3(a) is used. In Fig. 3 (&), 21 is a heater, 22 is a heat insulator, 24 is a furnace tube,
The laminate 5 of glass fine particles is supported by a rotatable support rod 2.
3) and inserted into the furnace at standby temperature. Thereafter, as shown in the time/furnace temperature graph in Figure 3, etc., the furnace temperature is gradually raised, and finally the layered body of glass fine particles becomes transparent. It is also possible to dehydrate the glass particles or add fluorine or the like to the glass particles using the period until the glass particle laminate becomes transparent. - In the method of Itsutsu 2, a device (zone furnace) as shown in Fig. 4, 6) is used. The meanings of the numbers in FIG. 4(a) are the same as those in FIG. 4(a). The laminated body 5 of glass particles is suspended from a support rod 2311C made to be rotatable and movable up and down, and is lowered and installed directly above the heater 21. Next, the temperature of the heater 21 is raised to a temperature suitable for dehydration, fluoridation, transparency, etc., and held at that temperature. is passed through a laminate 5 of glass fine particles held at a transparent temperature to become transparent [
1st to 3rd traverses, see FIG. 4(b)]. When the laminate 5 of glass fine particles has a cylindrical body of high-purity glass at its center or a structure without a cylindrical body, the laminate of glass fine particles can be made into a straight cylindrical shape by transparent vitrification using the above two methods. It can be a rod or a cylindrical pipe.

[Problem that the invention seeks to solve]

However, if the stack of glass particles has a structure with a cylindrical rod or cylindrical pipe made of high-purity glass at its center, depending on the conditions of heat treatment and transparency, it may become a straight cylindrical body (rod) or cylindrical body (pipe). I couldn't get it.

In other words, as shown in FIG. 5, the song having a distance t from the horizontal plane was distorted. If the obtained rod or pipe is bent, not only will it take more time to process it later, but if the rod or pipe has a refractive index distribution, the refractive index distribution will no longer be eccentrically concentric, making it difficult to use as a base material for optical fibers. There was a problem in that the eccentricity ratio increased when used as

The present invention solves the above-mentioned problems and aims at a method of manufacturing a glass rod or i-glass pipe without bending even from a glass fine particle laminate having a high-purity glass cylinder or cylindrical body at its center.

[Means for Solving the Problems] As a result of the inventors' investigation into the cause of the bending that occurs in cylinders or cylindrical bodies as described in the above-mentioned problem with the prior art, it was found that the cause was a laminate of glass particles. was found to be the temperature at which it contracts. This temperature varies depending on the material that makes up the laminate of glass particles, so
Generally, it is preferable to define it by the "viscosity" of the glass. The inventors confirmed that the viscosity of glass was 10
' When the laminate of glass particles was contracted at a temperature higher than poise, the curvature of the cylindrical rod or cylindrical pipe became large.

A viscosity of 10' poise corresponds to 1500° C. for pure 5ill glass and 1350° C. for quartz glass with one weight of fluorine incorporated. However, even in a temperature range where the viscosity was 10' poise or more, when the shrinkage rate was 15 or less, no bending occurred which would be a problem in actual use.

Based on these facts, the inventors of the present invention believe that the viscosity of glass is 10
'If the shrinkage rate of the glass fine particle laminate in the temperature range of 15% or less in a temperature range of 15% or higher, a cylindrical body (glass rod) or cylindrical body (glass pipe) with little bending can be achieved.
I learned that I can get . The viscosity of glass is '``' 1
) In a temperature range of O1se or higher, the laminate of glass particles practically does not shrink. Note that the shrinkage rate in this specification is (reduction in length during heating/length before heat treatment) x 100 (
4) Hail upon you. Therefore, if the shrinkage rate is 15, the volume will be about 6 cL as much as before the heat treatment.

The present invention, which has been achieved based on the above knowledge, consists of laminating glass fine particles on the surface of a first cylindrical body or cylindrical body made of high-purity glass, and then transparentizing the laminated glass fine particles in a high-temperature furnace. In a method of manufacturing a cylindrical body or a cylindrical body,
The viscosity of glass is less than 10'p
characterized in that the shrinkage rate of the laminate of glass particles is 15 factors or less in a temperature range of 15 oise or higher;
A method for manufacturing a glass article.

Particularly preferred embodiments of the invention include the following. That is, a soaking furnace is used as a high-temperature furnace, and the viscosity of the glass is 1016 poise or less, 109 p.
The average rate of increase in furnace temperature in the temperature range above oise is 2
℃/min or more, and a zone furnace is used as the high temperature furnace, and the viscosity of the glass is 1016 po1s.
The above method is carried out in a temperature range of 10'poiqe or less, and the time the glass fine particle laminate remains inside the heater is 30 minutes or less.

In the present invention, the viscosity of the glass is 1 ol 11 pois.
By setting the shrinkage rate of the glass fine particle laminate to a factor of 15 or less in a temperature range of 1D' poise or more, bending of the glass body after transparentization can be prevented, but the reason for this is as follows. That's right.

The relationship between glass viscosity and shrinkage can be shown as shown in Table 1.

Table 1 As is clear from the table, contraction occurs when the viscosity is less than 1016 poise, but between 1026 and 169 poise.
In the temperature range where the viscosity of θ occurs, a force that causes bending acts. Therefore, this viscosity is 1016 to 109 pois
The shrinkage is suppressed in the temperature range where the viscosity is 10.
'Bending can be prevented by allowing it to occur in a temperature range below poise. According to detailed studies by the present inventors, if the shrinkage rate in the temperature range where the viscosity is 1016 to 10' poi8e is set to 15 factors or less, bending does not occur in this temperature range.

By the way, Figure 2 is a graph showing the relationship between temperature and length of the laminate when the laminate is made transparent using a soaking furnace.The vertical axis represents the length of the laminate, and the horizontal axis represents the temperature. shows. The white line A (solid line) in the same figure shows the case where the temperature increase rate is small (1°C/min), and the initial length of the laminate is Z! , the length after heating is t2
It is. In addition, the temperature rise rate is large at the curved opening (dashed line) (
3°C/min), the initial length of the laminate is t1', and the length after heating is 1. B. The contraction rate of the mouth is expressed as.

As is clear from Figure 2, the shrinkage rate depends not only on the temperature but also on the holding time at that temperature.
If it is 0℃/min or more (curved mouth) η== 1016~1
It can be seen that the time that the base material is held at the temperature of 09 is short, and therefore the shrinkage rate in that temperature range is small, which has a favorable effect on the bending of the base material.

Therefore, in the present invention, the viscosity of the glass is 1016
As a method for reducing the shrinkage rate of the laminate to 15 coefficients or less in the temperature range of ~109 poise, for example, when using a soaking furnace, the average heating rate of the furnace temperature in the above temperature range is set to 2
℃/min or more, or when using a zone furnace, the time the laminate is inside the heater in the above temperature range is 3.
Examples include a method in which the heating time is set to 0 minutes or less. However, the method is not limited to these examples, and the glass viscosity is 10
Means for reducing the contraction rate of the laminate to 15 factors or less in the temperature range of 16 to 109 poise [Example] Example 1 On the surface of the glass rod 1 whose center is quartz glass containing Ge01 and whose surroundings are pure silica. The glass fine particles 3 produced from the torch 2 were laminated by the 0VPO method to form a glass fine particle deposit layer 4 to obtain a glass fine particle laminate 5 [FIG. 1(a)].

(b)]. The laminate 5 is inserted into a soaking furnace as shown in Fig. 3 (,), and the standby temperature is reached! Up to 71650℃, 53℃
The mixture was heated while increasing the temperature at a temperature increase rate of 1/2 min to form transparent glass [Figure 1 (C)].

The bending of the resulting glass rod with an outer diameter of 40 m and a total length of 300 wm was extremely small at t=200μ in FIG. Furthermore, when this glass rod was spun, the loss at an eccentricity of 184 and a wavelength of 1.55μ was 0.
．． A good fiber of 23 dB/km was obtained.

The eccentricity of the fiber is It is expressed as

In Example 1, the viscosity of the laminate 4 is 10' poise at about 1500°C. A laminate made to the same size under the same conditions as described above was placed in a soaking furnace and heated at a heating rate of 53°C/min to 1500°C showing a viscosity of 10' poise from the standby temperature. When it was immediately taken out of the furnace and its shrinkage rate was measured, it was found to be 13 inches.

Comparative Example 1 A glass particle laminate prepared in the same manner as in Example 1 was inserted into a soaking furnace as shown in Figure 3(a), and the temperature was raised from the standby temperature to 1400°C at a rate of 1.5°C/min. , then 1400
It was held at ℃ for 2 hours to form transparent vitrification (Fig. 6). At this time, the viscosity of the glass at 1400°C is 10'p
oise or more, the shrinkage rate was 55% (transparent).

The curve of the resulting glass rod with an outer diameter of 40 cm and a total length of 300 cm is large as t=S in Fig. 5.
Furthermore, the eccentricity of the fiber obtained by spinning this glass rod was as large as 2.

Example 2 The center was made of pure silica and the surrounding area was made of quartz glass in which 1 weight of fluorine was incorporated. Glass particles were laminated on the surface of the glass rod by the WAD method to obtain a laminate having an outer diameter of 110 m and a total length of 450 m. The laminate was placed in a soaking furnace as shown in Fig. 3(a), and the standby temperature was raised to 91 soo℃ and 3℃/
The mixture was heated while increasing the temperature over a period of 30 minutes, and turned into transparent vitrification. The temperature at which the viscosity becomes 10" poise is approximately 1
The laminate was heated at 350° C. under the same conditions and the temperature was raised to 1350° C., and when it was taken out immediately at 9 o'clock, the shrinkage rate was 12 mm. In addition, the gas introduced into the furnace is He at temperatures below 1100°C.
100%, 8iF4 from 1100℃ to 1500℃
5'A, He was 97%. The bending of the resulting glass rod with an outer diameter of 40 and a length of 300 cm was extremely small as t=150p in FIG. Also,
When this glass rod was spun, the eccentricity was 1.0%.
The fiber had a good loss at 1.55 μ (L 21 ap/7).

Example 3 A laminate of glass particles produced in the same manner as in Example 2 was heat-treated and made transparent using a zone furnace as shown in FIG. 4(a). The heater length of this zone furnace is 150m.
The conditions for heat treatment and transparency are shown in Table 2.

Table 2 In the first step, fluorine is added to the laminate of glass particles, and in the second step, the laminate is made into transparent glass while preventing volatilization of the fluorine. The viscosity of the glass in the first stage is 101' I) O1s
The shrinkage rate at this time was as small as 8%. The bending of the glass rod with an outer diameter of 40 m and a length of 300 m obtained by this method was extremely small at t = 250 μ in Fig. 5, and when this glass rod was spun, the eccentricity was 1.1%. A good fiber was obtained with a loss of 0.21 dB/b at 55μ.

Comparative Example 2 A laminate of glass particles was created in the same manner as in Example 3,
Heat treated and made transparent. Table 3 shows the conditions for heat treatment and transparency.
It is as follows.

Table 3 The viscosity of the glass in the first stage is approximately 10!0 poise.

The shrinkage rate of the glass was 18, and bending was already occurring. The curve of the glass rod with an outer diameter of 40 m and a length of 500 m obtained by this method was as large as t=e■ in relation to t in Figure 5, and when the curve was corrected and spun into fiber, the eccentricity was as large as 4%. .

〔Effect of the invention〕

If a laminate of glass particles is heat-treated to make it transparent within the scope of the present invention, a cylindrical rod or cylindrical pipe with less bending can be obtained.

By using this cylindrical rod or cylindrical pipe, it is possible to manufacture an optical fiber with less eccentricity and less effort in processing.

[Brief explanation of drawings]

FIGS. 1(a) to 1(c) are diagrams illustrating Example 1 of the present invention, in which (a) and (b) are side views and cross-sectional views showing the step of forming a glass fine particle laminate, and (C) Figure 2 is a graph showing the relationship between glass temperature and shrinkage rate, and Figure 3 (a) is an explanatory diagram of a soaking furnace. , Figure 4(b) is a diagram showing the process order of transparency and temporal adjustment of furnace temperature when using a soaking furnace, Figure 4(a) is an explanatory diagram of a zone furnace, and Figure 4(b) is an illustration of a zone furnace. Figure 5 is a cross-sectional view illustrating the bending of the glass laminate; Figure 6N is a diagram showing the process order and adjustment over time in Comparison flllJ 1. It is.

Claims (3)

[Claims] (1) After laminating glass particles on the surface of a first cylinder or cylindrical body made of high-purity glass, the laminated glass particles are made transparent in a high-temperature furnace to produce a second cylinder or cylindrical body. In this method, the viscosity of the glass is 10^1^6
A method for manufacturing a glass article, characterized in that the shrinkage rate of a laminate of glass particles is 15% or less in a temperature range of 10^9 poise or less. (2) A soaking furnace is used as a high-temperature furnace, and the viscosity of the glass is 1.
The method according to claim (1), wherein the method is carried out at an average rate of increase in the furnace temperature of 2° C./min or more in a temperature range of 0^1^6 poise or less and 10^9 poise or more. (3) Using a zone furnace as a high-temperature furnace, the temperature range is such that the viscosity of the glass is 10^1^6 poise or less and 10^9 poise or more, and the time that the glass fine particle stack remains inside the heater is 30 minutes or less. Claim No. (
The method described in section 1).