JP5793834B2 - GLASS PARTICLE DEPOSITING METHOD AND GLASS - Google Patents

Description

  The present invention relates to a method for producing a glass particulate deposit and a method for producing a glass body.

  An optical fiber is manufactured by heating and softening one end of a glass base material having a substantially cylindrical shape and drawing. Moreover, the manufacturing method of the glass base material for optical fibers includes a deposition step of manufacturing a glass particulate deposit by an OVD method, a VAD method, and the like, and a transparent glass body by heating the glass particulate deposit to produce a transparent glass body. Process. Patent Documents 1 and 2 disclose a method for producing a glass particulate deposit or a method for producing a glass.

  The invention disclosed in Patent Document 1 aims to reduce the manufacturing cost by using parts with low heat resistance and extending the life of the parts. The method for producing a glass fine particle deposit disclosed in Patent Document 1 is to heat and vaporize a glass raw material under reduced pressure to produce a glass raw material gas, and to guide the glass raw material gas to a glass fine particle forming burner through a pipe under reduced pressure. For example, it is possible to use a pipe made of a vinyl chloride material having a heat resistance temperature of about 70 ° C. with a pipe temperature of 55 ° C.

  An object of the invention disclosed in Patent Document 2 is to avoid the generation of bubbles and white turbidity due to the unstable flow rate of the glass raw material gas at the start of the deposition of glass fine particles. The method for producing a glass particulate deposit disclosed in Patent Document 2 starts the deposition of glass particulates after discarding the glass source gas for a predetermined time prior to the start of the deposition of the glass particulates, By making the pressure in the pipe and the temperature of the pipe satisfy a predetermined relationship, generation of bubbles and cloudiness is avoided. The piping temperature is 82 ° C. or 85 ° C.

JP 2004-161555 A JP 2006-342031 A

  Although it is desired to improve the ratio of the amount of glass fine particles deposited to the amount of glass raw material gas supply (raw material yield), the conventional method for producing a glass fine particle deposit including the inventions disclosed in Patent Documents 1 and 2 is the raw material yield. There is a limit to improvement. The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for producing a glass fine particle deposit and a method for producing a glass body that can improve the raw material yield.

The glass fine particle deposit manufacturing method of the present invention heats and vaporizes a glass raw material contained in a raw material container to make a glass raw material gas, and this glass raw material gas is led from the raw material container to a glass fine particle forming burner through a pipe. Including a deposition step in which a glass raw material gas is ejected from a fine particle forming burner, and glass fine particles generated by a flame decomposition reaction of the glass raw material gas are deposited on a starting material to produce a glass fine particle deposit. The temperature of at least a part of the pipe to the glass fine particle forming burner is controlled to be a predetermined temperature of 150 ° C. or higher by a heating element , and the temperature management part is made of a fluororesin material having a heat resistant temperature of 170 to 260 ° C. It is characterized by using a thing.

  In the method for producing a glass fine particle deposit according to the present invention, a tape heater is wound around the outer periphery of a pipe in at least a part of the pipe from the raw material container to the glass fine particle forming burner, and the tape heater is energized in the deposition process. It is preferable to heat the pipe. Further, it is preferable that a heat insulating material is provided on the outer periphery of the heating element or the tape heater.

  The glass body production method of the present invention is produced by producing a glass fine particle deposit by the above-mentioned glass fine particle deposit production method of the present invention, and manufacturing the glass body through a transparentizing step of heating and clarifying the glass fine particle deposit. It is characterized by doing. Further, it is preferable to produce a glass fine particle deposit by an OVD method, a VAD method or an MMD (multi-burner multi-layering) method in a deposition process, and to produce a glass body as a glass base material for an optical fiber through a transparency process. is there.

  According to the present invention, the raw material yield can be improved.

It is a flowchart of the glass body manufacturing method of this embodiment. It is a figure explaining fixing process S1 of the glass body manufacturing method of this embodiment. It is a figure explaining deposition process S2 of the glass body manufacturing method of this embodiment. It is a figure explaining drawing-out process S3 of the glass body manufacturing method of this embodiment. It is a figure explaining transparentization process S4 of the glass body manufacturing method of this embodiment. It is a figure explaining solidification process S5 of the glass body manufacturing method of this embodiment. It is a figure explaining the deposition process of the glass body manufacturing method of other embodiment. It is a figure explaining the deposition process of the glass body manufacturing method of other embodiment. 6 is a chart summarizing various conditions and raw material yields of Examples and Comparative Examples.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Moreover, below, the glass body manufacturing method (including the glass fine particle deposit body manufacturing method) which manufactures the glass body as a glass base material for optical fibers is demonstrated.

  FIG. 1 is a flowchart of the glass body manufacturing method of the present embodiment. As shown in this figure, the glass body manufacturing method of the present embodiment includes a fixing step S1, a deposition step S2, a drawing step S3, a clearing step S4 and a solidifying step S5 in this order, and a glass preform for an optical fiber. As a glass body. In addition, the glass body manufactured by this glass body manufacturing method is, for example, an optical fiber base material for manufacturing an optical fiber by drawing, or a core to be a core portion of the optical fiber base material. It is a base material. In addition, although the manufacturing method of the glass body by OVD method was shown in this embodiment, the same effect is acquired also in VAD method and MMD method.

  FIG. 2 is a diagram for explaining the fixing step S1 of the glass body manufacturing method of the present embodiment. FIG. 3 is a view for explaining the deposition step S2 of the glass body manufacturing method of the present embodiment. FIG. 4 is a view for explaining the drawing step S3 of the glass body manufacturing method of the present embodiment. FIG. 5 is a diagram for explaining the transparency step S4 of the glass body manufacturing method of the present embodiment. Moreover, FIG. 6 is a figure explaining solidification process S5 of the glass body manufacturing method of this embodiment.

  In the fixing step S1 (FIG. 2), the starting rod 11 is inserted into the seed rod pipe 12 and fixed so that the tip end portion 11a of the starting rod 11 protrudes from the one end 12a of the seed rod pipe 12, whereby the starting rod 10 Is produced (see FIGS. 1A and 1B). The starting rod 11 is made of a material such as alumina, glass, refractory ceramics, or carbon. The seed rod pipe 12 is made of quartz glass. In the starting rod 10, a carbon film 11 b is preferably formed on the outer periphery of the portion of the starting rod 11 protruding from the one end 12 a of the seed rod pipe 12 by a flame from the burner 20 using a city gas burner or an acetylene burner. ((C) in the figure). Even during the formation of the carbon film in FIG. 3C, the starting rod 10 rotates about the central axis of the starting rod 11, and the burner 20 moves relative to the starting rod 10 along the axial direction of the starting rod 11. Repeat reciprocating motion.

  In the deposition step S2 (FIG. 3) after the fixing step S1, the starting rod 10 in which the starting rod 11 is inserted and fixed in the seed rod pipe 12 is rotated about the central axis of the starting rod 11. Further, the glass fine particle synthesis burner 21 that is arranged on the side of the starting rod 10 and forms an oxyhydrogen flame repeats reciprocating movement relative to the starting rod 10 along the axial direction of the starting rod 11.

In the deposition step S2, a glass raw material (SiCl ₄ , GeCl ₄ , etc.) contained in the raw material container 31 is heated and vaporized to obtain a glass raw material gas. GeCl _{4 has} a boiling point of 84 ° C., and SiCl _{4 has} a boiling point of 57 ° C. The glass raw material gas is guided from the raw material container 31 to the glass fine particle forming burner 21 through the pipe 32 and is ejected from the glass fine particle forming burner 21. An MFC 34 is provided in the pipe 32 to control the raw material gas flow rate, and the raw material container 31, the pipe 32, and the MFC 34 are placed in the temperature control booth 35 and the temperature is controlled. When two types of source gases are used, two source containers and pipes may be provided. Moreover, the inside of the raw material container 31 and the temperature control booth 35 is managed at a temperature equal to or higher than the boiling point of the raw material gas. It is desirable to manage the piping to the burner at a temperature not lower than the boiling point of the full length raw material gas.

  Then, by the OVD method, the glass fine particles generated by the flame decomposition reaction (thermal decomposition reaction, flame hydrolysis reaction, thermal oxidation reaction, etc.) of the glass raw material gas ejected from the glass fine particle forming burner 21 are used as the starting material (starting rod). 10) to produce a glass particulate deposit. At this time, glass fine particles are deposited on the outer periphery of the starting rod 10 from the tip portion 11a of the starting rod 11 to a part of the seed rod pipe 12, whereby the glass fine particle deposit 13 is produced.

  In the deposition step S2, the amount of the glass raw material gas supplied by the glass fine particle synthesis burner 21 is varied for each traverse. Thereby, the glass fine particles deposited on the outer periphery of the starting rod 11 have a predetermined composition distribution in the radial direction (that is, a refractive index distribution in the radial direction in the subsequent glass preform or optical fiber).

  In particular, in the present embodiment, in the deposition step S2, the temperature of at least a part of the pipe 32 from the raw material container 31 to the glass fine particle forming burner 21 is managed to be a predetermined temperature of 100 ° C. or more by the heating element. The temperature of the pipe 32 is preferably managed to be a predetermined temperature of 120 ° C. or higher, and more preferably the temperature of the pipe 32 is further controlled to be a predetermined temperature of 150 ° C. or higher. . As the pipe 32, a pipe made of a fluorine resin material having a heat resistant temperature of about 170 to 260 ° C. can be used.

  Various means can be employed to heat the pipe 32. As this heating means, it is preferable that a tape heater 33 is wound around the outer periphery of the pipe 32 in at least a part of the pipe 32 from the raw material container 31 to the glass particle forming burner 21. The tape heater is a flexible heater in which an extremely fine twisted wire of a metal heating element or a carbon fibrous surface heating element is covered with a heat resistant material. The pipe 32 is heated by energizing the tape heater 33 in the deposition step S2. Moreover, it is preferable from the viewpoint of low power consumption that a heat insulating material is provided on the outer periphery of the tape heater 33. As other heating means, it is possible to employ a means for supplying current to the metal pipe 32 for heating, a means for putting the pipe 32 in the temperature control booth, or the like.

  In the extraction step S3 (FIG. 4) after the deposition step S2, the starting rod 11 is extracted from the seed rod pipe 12 and the glass particulate deposit 13. At this time, the seed rod pipe 12 and the glass fine particle deposit 13 remain fixed to each other. In addition, in order to form a carbon film on the outer periphery of the portion of the starting rod 11 protruding from the one end 12a of the seed rod pipe 12 in the fixing step S1, when the starting rod 11 is pulled out in this drawing step S3, the glass particulate deposit 13 The inner wall surface of the center hole is prevented from being scratched.

In the clearing step S4 (FIG. 5) after the drawing step S3, the glass fine particle deposit 13 is placed inside the heating furnace 22 into which He gas and Cl ₂ gas are introduced, together with the integrated seed rod pipe 12. And heated by the heater 23 to be transparent. Thereby, the transparent glass tube material 14 is produced.

In the solidification step S5 (FIG. 6) after the transparentization step S4, the transparent glass tube 14 is placed in a heating furnace and rotated, and SF ₆ is introduced into the center hole and heated by the heater 24. The inner wall surface of the center hole is vapor-phase etched (FIG. 1A). Next, the transparent glass tube material 14 is decompressed and heated by the heater 24 to be solidified (FIG. 5B), thereby producing a solid glass base material.

  The transparent glass base material 15 thus manufactured is further preformed by forming clad glass on the outside by the VAD method (see FIG. 7), the OVD method, or the MMD method (see FIG. 8). Then, the tip is heated and softened and drawn to produce an optical fiber. Also in the VAD method, OVD method, and MMD method for forming the clad glass, in the deposition process, the temperature of at least a part of the pipe 32 from the raw material container 31 to the glass particle forming burner 21 is 100 ° C. or more by the heating element. It is managed to reach a predetermined temperature. The piping temperature is preferably managed so as to be a predetermined temperature of 120 ° C. or higher, more preferably managed so as to be a predetermined temperature of 150 ° C. or higher.

  In the present embodiment, in the deposition step S2, the temperature of at least a part of the piping 32 from the raw material container 31 to the glass fine particle forming burner 21 is 100 ° C. or higher (preferably 120 ° C. or higher, more preferably, due to the heating element). The raw material yield is improved by controlling the temperature to be a predetermined temperature of 150 ° C. or higher.

  Next, examples of the glass particle deposition body manufacturing method and the glass body manufacturing method will be described. In the present embodiment, a glass base material for manufacturing a core of a graded index type optical fiber by drawing is manufactured.

  In the deposition step S2, an OVD apparatus is used to deposit glass particles. The starting rod 11 is made of alumina having an outer diameter of 9 to 10 mm and a length of 1200 mm. The seed rod pipe 12 is made of quartz glass having a length of 600 mm, an outer diameter of 20 to 40 mm, and an inner diameter of 9.8 to 21 mm.

The glass raw material gases introduced into the glass fine particle synthesis burner 21 forming an oxyhydrogen flame in the deposition step S2 are SiCl ₄ (input amount 1 to 3 SLM / piece) and GeCl ₄ (input amount 0.0 to 0.3 SLM). It is.

  The tape heater 33 is wound around the outer periphery of the pipe 32 from the raw material container 31 to the glass particle forming burner 21, and the pipe 32 is heated by energizing the tape heater 33 in the deposition step S <b> 2. A heat insulating tape is wound around the outer periphery in a single or double manner.

FIG. 9 is a chart summarizing various conditions and raw material yields of the examples and comparative examples. The average raw material yield X (%) and power consumption Y (%) of SiCl ₄ and GeCl ₄ are compared and evaluated for each value of the piping temperature A (° C.). The power consumption is a relative value with the power consumption of Example 1 as 50%.

  As shown in this chart, in Comparative Example 1 in which the piping temperature A is 90 ° C., the average raw material yield X is 30%, and in Comparative Example 2 in which the piping temperature A is 85 ° C., the average raw material yield X is 27%. However, in Example 1 where the piping temperature A was 100 ° C., the average raw material yield X was 32%, and in Example 2 where the piping temperature A was 120 ° C., the average raw material yield X was Is 34%, and in Examples 3 to 5 in which the piping temperature A is 150 ° C., the average raw material yield X is 37%. In addition, among Examples 3 to 5 in which the pipe temperature A is 150 ° C., the power consumption Y is 85% in Example 3 in which the heat insulating tape is not wound, whereas the heat insulating tape is wound in a single layer. In the attached Example 4, the power consumption Y is 60%, and in the Example 5 in which the heat insulating tape is wound twice, the power consumption Y is 55%.

Thus, the higher the piping temperature, the higher the raw material yield. In particular, it can be seen that the raw material yield sharply improves when the piping temperature is 100 ° C. or higher. This is due to the temperature rise of the source gas
SiCl ₄ + 2H ₂ O → SiO ₂ + 4HCl
GeCl ₄ + 2H ₂ O → GeO ₂ + 4HCl
It is considered that this is because the glass fine particle formation reaction (hydrolysis reaction) represented by the formula (2) is promoted and the generation amount and the aggregation rate of the glass fine particles are increased. Moreover, it can be said that the cost of electric power is reduced by winding the heat insulating material, and the cost is further reduced when the heat insulating material is wound in layers.

The present invention is not limited to the above embodiment, and various modifications can be made. In the above embodiment, the glass particulate deposit is manufactured by the OVD method in the deposition step. However, the present invention is effective in the all glass particulate deposition method using a flame decomposition reaction such as the VAD method or the MMD method in the deposition step. In this embodiment, SiCl ₄ and GeCl ₄ are used as the source gas. However, in the case of clad glass synthesis using only SiCl ₄ , there is an effect of improving the source yield.

DESCRIPTION OF SYMBOLS 10 ... Departure rod, 11 ... Departure rod, 12 ... Seed rod pipe, 13 ... Glass particulate deposit, 14 ... Transparent glass tube, 20 ... Burner, 21 ... Glass particulate synthesis burner, 22 ... Heating furnace, 23, 24 ... Heater, 31 ... Raw material container, 32 ... Piping, 33 ... Tape heater, 34 ... MFC,
35 ... Temperature control booth.

Claims (5)

The glass raw material contained in the raw material container is heated and vaporized to obtain a glass raw material gas. This glass raw material gas is led from the raw material container to the glass fine particle forming burner through a pipe, and the glass raw material gas is ejected from the glass fine particle forming burner. In the method for producing a glass particulate deposit including a deposition step of producing a glass particulate deposit by depositing glass particulate generated by a flame decomposition reaction of the glass raw material gas on a starting material,
In this deposition step, the temperature of at least a part of the pipe from the raw material container to the glass particle forming burner is controlled to be a predetermined temperature of 150 ° C. or higher by a heating element, and the heat- resistant temperature 170 Use a material of a fluororesin material of ~ 260 ° C,
A method for producing a glass fine particle deposit, wherein: A tape heater is wound around the outer circumference of the pipe in at least a part of the pipe from the raw material container to the glass particle forming burner, and the pipe heater is heated by energizing the tape heater in the deposition step. To
The method for producing a glass particulate deposit according to claim 1 . The method for producing a glass particulate deposit according to claim 1 or 2 , wherein a heat insulating material is provided on an outer periphery of the heating element or the tape heater. A glass particulate deposit is produced by the glass particulate deposit production method according to any one of claims 1 to 3 ,
A glass body is manufactured through a transparentization step of heating the glass fine particle deposit to make it transparent.
A glass body manufacturing method characterized by the above. In the deposition step, a glass particulate deposit is manufactured by the OVD method, VAD method or MMD method,
Producing the glass body as a glass preform for optical fiber through the transparentization step,
The glass body manufacturing method of Claim 4 characterized by the above-mentioned.

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