Patent Application
20200262735
The present disclosure relates to a method for producing a glass particulate deposit, a method for producing a glass preform, and a glass preform.
This present application claims priority based on Japanese Patent Application No. 2017-164239 filed on Aug. 29, 2017, the contents of which are incorporated herein by reference in its entirety.
The vapor phase synthesis method, in which a rotating starting rod and a burner arranged to face the starting rod are relatively reciprocated (traversed), and glass particulates generated by the burner are sprayed to a surface of the starting rod to be deposited in a layered manner, is known. A method for producing a glass particulate deposit by the vapor phase synthesis method is disclosed in the following related art documents.
Patent Literature 1 discloses that when the relative reciprocating movement between the rod and the burner performs one reciprocation and returns to the original position, the reciprocating movement speed and the rotation speed of the rod are adjusted in accordance with a reciprocating movement distance of one reciprocation so that the rotational position of the rod is shifted from the original position by a half cycle.
Patent Literature 2 discloses that a value represented by A=(r/v)×L0 is set so as to be in a range of 40≥A≥8 when a plurality of burners are disposed at equal intervals, and the reciprocating movement speed v mm/min, rotation speed r rotations/min, and burner interval set value L0 mm of the rod are used as parameters.
Patent Literature 1: JP2013-043810
Patent Literature 2: JP2002-167228
A method for producing a glass particulate deposit according to the present disclosure is provided, which
disposes at least one burner at a position facing a rod that rotates around the axis, and sprays glass particulates generated in a flame from the burner to the rod while relatively reciprocating the rod and the burner in an axis direction of the rod, to deposit the glass particulates,
in which a relation of 0.1 W≤V/R≤1.0 W is satisfied, where W mm represents a luminance width of a flame of glass raw material, R rotations/min represents a rotational speed of the rod, and V mm/min represents a speed of the reciprocation.
In addition, a method for producing a glass preform according to the present disclosure is provided, which includes a transparentizing process of producing a glass particulate deposit by the method for producing a glass particulate deposit described above, and heating the produced glass particulate deposit to produce a transparent glass preform.
Further, a glass preform according to the present disclosure is provided, which has a variation rate of an outer diameter of 5% or less in a longitudinal direction.
However, it is desired to further suppress the variation in the outer diameter of the glass particulate deposit in the longitudinal direction than the techniques of Patent Literatures 1 and 2.
Therefore, an object of the present disclosure is to provide a method for producing a glass particulate deposit having a smaller variation in the outer diameter in the longitudinal direction than the related art, a method for producing a glass preform, and a glass preform.
According to the present disclosure, it is possible to produce a glass particulate deposit having a small variation in the outer diameter in the longitudinal direction.
First, the contents of the embodiments of the present disclosure will be listed and described.
Note that the present disclosure is not limited to these exemplifications, but is indicated by the claims, and includes all modifications within the scope and meaning equivalent to the scope of the claims.
A method for producing a glass particulate deposit according to an aspect of the present disclosure is
(1) a method for producing a glass particulate deposit, which disposes at least one burner at a position facing a rod that rotates around the axis; and sprays glass particulates generated in a flame from the burner to the rod while relatively reciprocating the rod and the burner in an axis direction of the rod, to deposit the glass particulates, and
in which a relation of 0.1 W≤V/R≤1.0 W is satisfied, where W mm represents a luminance width of a flame of glass raw material, R rotations/min represents a rotational speed of the rod, and V mm/min represents a speed of the reciprocation.
With this configuration, it is possible to produce a glass particulate deposit having a small variation in the outer diameter in the longitudinal direction.
(2) It is preferable that a relation of 0.1 W≤V/R≤0.5 W is satisfied, where W represents the luminance width, R represents the rotational speed, and V mm/min represents the speed of the reciprocation.
With this configuration, it is possible to produce a glass particulate deposit having a small variation in the outer diameter in the longitudinal direction.
(3) It is preferable to use siloxane as the glass raw material.
With this configuration, the raw material used does not contain corrosive halogen, so that the problem of corrosion of the producing apparatus or the like due to the exhaust gas and the exhaust gas treatment equipment can be eliminated. Further, since siloxane has high combustibility, the production efficiency of the glass particulate deposit can be increased.
(4) It is preferable to use octamethylcyclotetrasiloxane (OMCTS) as the siloxane.
With this configuration, the raw materials used can be easily obtained industrially, and allow ease of storage and handling.
(5) In addition, the method for producing a glass preform according to an aspect of the present disclosure includes a transparentizing process of producing a glass particulate deposit by the method for producing a glass particulate deposit of any one of (1) to (4), and heating the produced glass particulate deposit to produce a transparent glass preform.
With this configuration, a high-quality glass preform can be produced.
(6) The glass preform according to an aspect of the present disclosure has a variation rate of an outer diameter of 5% or less in a longitudinal direction.
With this configuration, when the glass preform is used for producing an optical fiber, it is possible to produce an optical fiber with little variation in optical characteristics in the longitudinal direction.
(7) Further, it is preferable that the variation rate of the outer diameter in the longitudinal direction is 1.5% or less.
With this configuration, it is possible to produce an optical fiber having a smaller variation in the optical characteristics in the longitudinal direction.
Hereinafter, an example of an embodiment of a method for producing a glass particulate deposit (hereinafter, also simply referred to as a “deposit”) and a method for producing a glass preform according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. In the drawings, the gas supply device for the flame forming gas is omitted, and the description in the text is also omitted.
Further, as a producing method described below, Outside Vapor Deposition (OVD) method will be described as an example, but the present disclosure is not limited to the OVD method. In addition to the OVD method, the present disclosure may be applied to a method of depositing glass from a glass raw material using a flame pyrolysis reaction such as, for example, a Multiburner Multilayer Deposition (MMD) method and the like that uses a plurality of burners.
As shown in
More specifically, as shown in
Here, R rotations/min represents the rotation speed of the rod, and V mm/min represents the reciprocating speed. V/R is equivalent to the axial movement distance during one rotation of the rod 12.
The flame radiated from the burner 13 will be described.
The flame radiated from the burner 13 is schematically shown in
In addition, in the raw material flame A, glass particulates are formed by burning the glass raw material, and the glass particulates are deposited on the outer periphery of the rod 12 as the particulates are sprayed to the rod 12.
There is no particular limitation on the glass raw material that is put into the flame and forms the raw material flame A, as long as it can generate glass particulates by the flame decomposition reaction or the oxidation reaction in the embodiment described above. Examples include silicon tetrachloride (SiCl4), siloxane, and the like. Among these, siloxane is preferable in that it does not generate corrosive gas such as chlorine and has high combustibility as compared with SiCl4, so that the production efficiency of the glass particulate deposit may be increased. Further, among siloxanes, cyclic siloxanes are preferred from the viewpoint of industrial availability and ease of storage and handling, and among these, octamethylcyclotetrasiloxane (OMCTS) is more preferable.
The gas for generating the flame is not particularly limited as long as the flame for generating glass particulates from the glass raw material can be formed by the burner. In general, hydrogen (H2) as a combustible gas, and oxygen (O2), nitrogen (N2), and the like as a combustion supporting gas can be appropriately mixed and used. In this case, it is preferable that hydrogen, oxygen, and nitrogen are ejected from separate ejection ports, respectively, and mixed after the ejection.
The width of the raw material flame A may be measured by measuring the luminance distribution (L(x, y)) of the flame C radiated from the burner 13, normalizing the measured luminance distribution (L(x, y)) with the maximum luminance Lmax, and, for example, binarizing the measured luminance distribution (L(x, y)) based on whether or not the portion satisfies L(x, y)/Lmax≥0.8.
Although the glass particulates are formed on the outer periphery of the rod 12 in a spiral band shape, for example, there occurs a gap portion where the glass particulates are not deposited, between the glass particulates in the deposited portion formed in the first round and the glass particulates in the deposited portion formed in the second round. In this case, when the reciprocating movement of the rod 12 is repeated many times and the glass particulate deposition layer is thickened, a deposit is formed, in which an outer diameter is varied in the longitudinal direction as shown in
Table 1 below shows the variation rate of outer diameter of the deposit 14 in the longitudinal direction when the V/R is in the range of 0.05 W to 1.40 W. The reciprocating movement of the rod 12 was performed 400 times, and the variation in the outer diameter was calculated by the following equation.
Variation in outer diameter [%]=(maximum variation in outer diameter/average outer diameter)×100
From the results in Table 1 above, it can be seen that the smaller the V/R is, the smaller the variation is in the outer diameter of the deposit 14 in the longitudinal direction.
However, when the V/R is extremely small, the glass particulates are deposited in a ball shape and the stress balance of the deposit 14 is uneven, and even during the deposition process, there is a high possibility of damage due to unexpected small impacts, or the like.
Considering the above comprehensively, it was found that when the V/R is in the range of 0.1 W to 1.0 W, a good deposit 14 having a small variation in the outer diameter in the longitudinal direction may be produced.
Therefore, in the present embodiment, in the process of depositing the glass particulates on the rod 12, the relation of 0.1 W≤V/R≤1.0 W is satisfied, where W mm represents the luminance width of the raw material flame radiated from the burner 13, R rotations/min represents the rotational speed of the rod 12, and V mm/min represents the speed of the reciprocation of the rod 12.
This is more preferable because, when V/R is in the range of 0.1 W to 0.5 W, the variation in the outer diameter is further reduced.
[Transparentizing Process]
The glass particulate deposit 14 obtained by the producing method described above was heated to 1100° C. in a mixed atmosphere of an inert gas and chlorine gas, and then heated to 1550° C. in a He atmosphere to obtain a transparent glass preform.
In addition, when the bulk density is uniform in the longitudinal direction, the variation rate of the outer diameter of the glass preform is substantially equal to the variation rate of the outer diameter of the glass particulate deposit. Therefore, the variation rate of the outer diameter of the glass preform obtained by consolidating the glass particulate deposit produced while varying the V/R as shown in Table 1 is substantially equal to the variation rate of the outer diameter shown in Table 1.
When the outer diameter of the glass preform varies in the longitudinal direction, the optical characteristics also vary at substantially the same rate. In order for the optical characteristics to be within the specification over the entire length in the longitudinal direction, it is preferable to suppress the variation in the optical characteristics to 5% or less, and more preferable to suppress the variation to 1.5% or less.
Therefore, as described above, when V/R is in the range of 0.1 W to 1.0 W, the optical characteristics in the longitudinal direction can be suppressed to 5% or less, and when the V/R is in the range of 0.1 W to 0.5 W, the optical characteristics in the longitudinal direction can be suppressed to 1.5% or less, thereby producing an optical fiber having excellent optical characteristics.
Note that, in the embodiment described above, although the glass raw material that is liquid is ejected from the burner 13 in a gas state, the glass raw material may be ejected from the burner 13 in a liquid spray state rather than being in the gas state. In an aspect in which the glass raw material is ejected from the burner 13 in the liquid spray state, the liquid raw material ejected from a liquid raw material port (not shown) of the burner 13 is atomized by applying a gas ejected from an ejection gas port (not shown). Examples of the gas ejected from the ejection gas port include nitrogen (N2), oxygen (O2), argon (Ar), and the like, and these are ejected alone or in combination.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-164239 | Aug 2017 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/031695 | 8/28/2018 | WO | 00 |
