JPH05339011A - Production of glass particulate deposited body - Google Patents

Abstract

PURPOSE:To forme a glass particulate deposited body with tight adhesion, efficiently and columnarly or cylindrically on the outer periphery of starting material. CONSTITUTION:In the synthesis of the glass particulate deposited body on the outer periphery of starting material by sheathing, the flow rate of combustion gas which forms a flame is controlled, so that the bulk density of the glass particulate deposited body produced for 10min from start of supply of the raw material is controlled to a range from 0.4 to 0.9g/cm<3>. Because the generation of a crack, a cleavage and the stripping at the time of firing, etc., is prevented, large sized and high quality glass particulate deposited body or transparent glass body is produced in lower reject rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a deposit of glass fine particles in a cylindrical or cylindrical shape on the outer peripheral portion of a starting material, and particularly when manufacturing a base material for an optical fiber which requires high purity. The present invention relates to a method for producing a composite body, which is preferably used for an intermediate product, and which includes a starting material and a glass fine particle deposit formed on the outer peripheral portion thereof.

[0002]

2. Description of the Related Art Conventionally, there is a so-called "external attachment method" as disclosed in JP-A-48-73522 as a method for producing a quartz glass tube or a base material for an optical fiber. This method involves depositing particulate glass such as SiO ₂ produced by a flame hydrolysis reaction of a glass raw material on the outer periphery of a refractory starting material such as rotating carbon, quartz glass or alumina, and a predetermined amount. After the deposition, the deposition is stopped, the starting material is drawn out to form a pipe-shaped glass aggregate, and the pipe-shaped glass aggregate is sintered and transparent vitrified in a high temperature electric furnace to obtain a pipe-shaped glass. Alternatively, a solid glass for optical fiber is used as a starting material in the same manner to form a composite of the starting material and a glass fine particle deposit, and then the starting material is not pulled out and the composite is heated in a high temperature furnace. There is also a method in which a transparent glass layer is further formed on the outer peripheral portion of the glass base material for an optical fiber, which is a starting material, by processing and sintering the portion of the glass fine particle deposit.

[0003]

Conventionally, in the above method, as shown in FIG. 1, one or a plurality of burners 2 for producing glass particles are used to synthesize a glass particle deposit. Generally, H ₂ , CH ₄ , C ₃ H ₈ or the like as a fuel gas and O ₂ , air or the like as a supporting gas are supplied from the tip of the burner 4 to form the flame 3. SiCl ₄ , GeCl ₄ or the like is supplied as a glass raw material into the flame 3, and glass particles SiO ₂ , GeO ₂ or the like are generated by the hydrolysis reaction. The glass particle deposit body 4 is formed by depositing the glass particles on the outer peripheral portion of the rotating starting material 1. As shown in FIG. 2, the glass particle deposit is small in the initial stage of forming the glass particle deposit. If the bulk density of the deposit at this early stage is low, soot cracking or peeling of the glass particulate deposit from the starting material occurs when sintering with the starting material left, and a good base material cannot be obtained. There was a problem. The present invention has been made for the purpose of preventing the occurrence of such defects and producing high-quality glass fine particles or glass bodies.

[0004]

According to the present invention, glass fine particles are synthesized from the vicinity of one end of a substantially cylindrical or cylindrical starting material rotating around its own axis on the outer peripheral portion of the starting material. Starting to deposit glass fine particles generated by supplying the glass raw material into the flame of the burner for use, and moving the burner relatively parallel to the axis of the starting material In the method of forming the glass particles in the outer peripheral portion in the axial direction, the bulk density of the glass particle deposit body synthesized within 10 minutes after starting the introduction of the raw material for depositing glass particles has a bulk density of 0.4 to 0.9 g / cm 3. It is characterized in that it is in the range of ³ , and by the method of the present invention, it is possible to prevent cracking of glass fine particles or peeling during sintering, and it is possible to manufacture a high quality base material. In the present invention, the supply pattern of the flow rate of the combustion gas that forms the flame is set so that the bulk density is 0.4 to 0.9 at the beginning of the deposition of the glass particles.
The amount of fine particles of glass is rapidly set by setting the amount Q ₁ to be g / cm ³ and then decreasing the combustion gas flow rate to the minimum value Q ₂ , and then the combustion gas flow rate is increased as the raw material flow rate increases. Increasing the flow rate to the constant flow rate Q ₃ can be mentioned as a particularly preferable embodiment. Further, the deposition surface temperature of the glass particulate deposit in the present invention is particularly preferably 950 ° C to 1200 ° C.

[0005]

When the bulk density of the deposited glass particles is low in the initial stage of seeding, the adhesion between the cylindrical or cylindrical starting material and the glass particles is not sufficient, and the weight of the glass particle deposit increases. And cannot bear the weight of itself, and cracks occur. Further, even if a good product is obtained at the stage of depositing glass fine particles, the rod and the glass fine particles are separated during sintering, and a high quality glass body cannot be obtained. As a result of repeated studies by the present inventors, it was found that the bulk density of glass fine particles in the initial stage of seeding should be 0.4 g / cm ³ or more in order to obtain a good sintered base material (glass body). I found it. When the bulk density is 0.4 g / cm ³ or more, the adhesion between the above-mentioned starting material and the glass fine particles becomes sufficient,
A high-quality glass body was obtained even when 20 kg of glass particle deposits were synthesized. On the other hand, when the bulk density is increased, the adhesion between the starting material and the glass particulate deposits is improved, but the flow rate of combustion gas must be increased to improve the bulk density, which increases the flame temperature. Therefore, the temperature of the starting material 1 (rod) itself is likely to rise in the initial stage where the deposition of glass particles is small, and as a result, a phenomenon in which the center of the starting material 1 is displaced from the center of rotation, that is, so-called "whip around" may occur. all right. The bulk density capable of suppressing whirling was 0.9 g / cm ³ or less. In order to deposit the glass particles having a bulk density of 0.4 to 0.9 g / cm ³ described above, the deposition surface temperature is set to 950 to 1200 ° C.
I also found that it needs to be suppressed to a certain degree. That is,
The bulk density in the initial stage of deposition needs to be increased to some extent and is set to 0.4 g / cm ³ or more, but after the initial stage, deposition growth of glass particles needs to be prioritized.

Therefore, in the present invention, the flow rate pattern of the combustion gas is used.
Flow rate Q at the initial stage of seeding, which is immediately after charging the raw material
₁(Depending on the amount of raw material input, the deposition surface temperature is 1050-
A flow rate of 1150 ° C is particularly preferable)
And gradually reduce the volume to a certain flow rate Q₂(Depending on the amount of raw material input
Although it is different, the deposition surface temperature may reach 950 to 1000 ° C.
Flow rate is especially preferable)
Flow rate Q in steady state according to the amount ₃(Depending on the amount of raw material input
However, a flow that causes the deposition surface temperature to rise to 1000 to 1050 ° C.
(The amount is especially preferable).
As a result, the bulk density at the initial stage of seeding is 0.4 to 0.9 g.
/ Cm³Is achieved, and glass particles are effectively deposited and grown.
It can be done efficiently.

[0007]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. [Example] Glass fine particle deposits were deposited with a triple flame burner having three combinations of hydrogen and oxygen. The raw material flow rate is gradually increased from 4 liters / minute to 15 liters / minute by 12
The dose was increased over 0 minutes. The hydrogen flow rate to the second port is the initial flow rate Q ₁ = 20 liters / minute for 5 minutes,
After that, reduce the volume to Q ₂ = 8 liters / minute over 5 minutes,
Then, it was set to increase Q ₃ = 15 liters / minute over 90 minutes. The synthesis of the glass fine particles was stopped 10 minutes after the raw material was charged, which is the initial stage of seeding, and the adhesion between the starting material and the glass fine particles and the bulk density of the glass fine particles at this time were measured. The bulk density was 0.67 g / cm ³ . When the temperature was measured with an infrared temperature image analyzer (thermoviewer), the deposition surface temperature was about 1080 ° C. Another starting material was prepared, and a glass particulate deposit was manufactured under the same condition settings.
The produced glass particle deposit had a diameter of 240 mm, a length of 800 mm and a weight of about 20 kg, but a good glass particle deposit was obtained without cracking. This glass fine particle deposit was inserted into a heating furnace maintained at 1550 ° C. to be transparent vitrified, and a good transparent glass body having a diameter of 100 mm and a length of 700 mm was obtained.

[Comparative Example 1] With the same configuration as that of the embodiment and the same flow rate of the raw material, the flow rate of hydrogen flowing through the second port Q ₁ = 12 liters / minute was supplied for 5 minutes, and then for 5 minutes. The amount was reduced to Q ₂ = 8 liters / minute, and further set to increase the steady flow rate Q ₃ = 15 liters / minute over 90 minutes. The synthesis of the glass fine particles was stopped 10 minutes after the raw material was charged, which is the initial stage of seeding, and the adhesion between the starting material and the glass fine particles and the bulk density of the glass fine particles at this point were measured. However, it was in a state of being easily peeled off when an impact was applied. The bulk density of the glass particles was also low at 0.35 g / cm ³ . Further, the deposition surface temperature was measured and found to be about 850 ° C. When another starting material was prepared and a glass fine particle deposit was manufactured under the same condition settings, the glass fine particle deposit had a diameter of 240 mm, a length of 800 mm and a weight of about 20 kg, but was a good glass particulate deposit. This glass particle deposit is 1550
It was inserted into a heating furnace kept at ℃ and tried to make it transparent.
The sintered base material was peeled off at the upper part of the seed of the glass particle deposit, which is considered to be due to insufficient adhesion at the initial stage of seeding.

[Comparative Example 2] With the same configuration as that of Example, and
Set the same raw material flow rate, and flow H to the second port ₁Flow rate
At 30 liters / minute for 5 minutes, then 90 minutes
Steady flow rate Q ₃= Reduce to 15 liters / minute
It was 10 minutes after the raw material is fed, which is the initial stage of seeding,
Of the starting material and glass particles at this point.
When the adhesion and the bulk density of the glass particles were measured,
Adhesion was strong enough and there were no cracks after sintering,
The degree is 1.05 g / cm³Becomes higher, and the formation of fine glass particles
The length was also suppressed as compared with the examples. In addition,
Rod heating is too strong and rod temperature rises and swings around
Occurred.

In the method of the present invention, the raw material is charged after the rod is heated at the initial flow rate (excluding the raw material gas) for about 1 to 5 minutes. In the above examples, this heating is 1
Minutes). Further, in each of the above-mentioned examples, the description has been made by taking H ₂ of two ports as an example, but it goes without saying that the flow pattern of the combustion gas shown in the embodiment is not limited to the case of two ports.

In the above embodiments, an example in which hydrogen is used as the combustion gas has been described, but the combustion gas is not limited to hydrogen, and similar effects can be obtained when CH ₄ , C ₃ H ₈ , CO or the like is used. Can be expected. Further, although the setting of the hydrogen flow rate is continuously changed, the setting does not have to be continuous, and the setting may be changed discontinuously.

[0012]

According to the present invention, the adhesion between the starting material and the glass particles at the initial stage of manufacturing the glass particle deposit can be enhanced, and the subsequent glass particle deposition and growth can be efficiently performed. Therefore, it is possible to manufacture a high-quality glass body without causing cracking or peeling even when manufacturing a large base material.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating an initial state of glass particle deposition in the production of glass particle deposits.

FIG. 3 is a graph showing an example of a change over time in the combustion gas flow rate in the method of the present invention, in which the horizontal axis represents time and the vertical axis represents the combustion gas flow rate (hydrogen in the examples).

[Explanation of sign]

 1 Starting Material 2 Burner 3 Flame 4 Glass Fine Particle Deposit 41 Glass Early Particle Deposit

Claims (3)

[Claims] 1. A glass in a flame of a burner for synthesizing glass particles, from the vicinity of one end of a substantially cylindrical or cylindrical starting material rotating around its own axis to the outer periphery of the starting material. Starting to deposit the glass fine particles generated by supplying the raw material, and moving the burner relatively in parallel to the axis of the starting material, thereby depositing the glass particulate deposit on the outer peripheral portion of the starting material in the axial direction. In the method of forming the glass fine particles, the bulk density of the glass fine particle deposits synthesized within 10 minutes after starting the introduction of the raw materials to start the deposition of the glass fine particles is in the range of 0.4 to 0.9 g / cm ^3. A method for producing a glass particulate deposit, which comprises depositing while controlling a flow rate of a combustion gas that forms a flame in a glass. 2. A combustion gas flow rate supply pattern for forming a flame is set to an amount Q ₁ at which a bulk density is 0.4 to 0.9 g / cm ³ in the initial stage of starting the deposition of glass particles, and thereafter combustion is performed. The gas flow rate is reduced to a minimum value Q ₂ to accelerate the deposition of glass particles, and then the combustion gas flow rate is increased to a steady state flow rate Q ₃ as the raw material flow rate is increased. 1. The method for producing a glass particle deposit according to 1. 3. The deposition surface temperature of the glass particulate deposit is 95.
It is 0 degreeC-1200 degreeC, The manufacturing method of the glass particle deposit body of Claim 1 or Claim 2 characterized by the above-mentioned.