JP2005187254A - Manufacturing method of glass body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a vaporization amount of an organic metal compound raw material in a method for producing a glass body by heating and gasifying and supplying a solid phase organic metal compound raw material to cause an oxidation reaction as compared with a conventional method. Another object of the present invention is to provide a method for producing a glass body capable of stably maintaining the supply amount per hour of the gasified organometallic compound raw material gas for a long time.
A glass main body and an organometallic compound that is a solid phase at room temperature are heated and vaporized by a CVD method and supplied to a reaction zone, and the glass main material and the organometallic compound are subjected to an oxidation reaction to form a glass body. The organometallic compound is heated and maintained at a temperature higher than the temperature at which the liquid phase appears, and is vaporized and supplied. Preferably, a carrier gas is brought into contact with the liquid phase of the organometallic compound to evaporate the organometallic compound and supplied to the reaction zone together with the carrier gas to obtain a glass body.
[Selection] Figure 2

Description

  The present invention relates to a method for producing a glass body comprising a step of reacting an evaporative gas obtained by heating a raw material of a solid phase and adding it to the glass body, and is used as an additive to the glass body, for example, in a solid state The present invention relates to a method for producing a glass body in which the amount of evaporation gas of a solid raw material such as an organometallic compound is increased and this is stably supplied.

As well known, as a typical method for producing a glass body such as quartz glass fiber, a glass main material such as SiCl ₄ and GeCl ₄ , POCl ₃ or the like added to control the optical properties of the glass body such as a refractive index, etc. Each of the dopant raw materials is vaporized and supplied together with a carrier gas to the reaction zone of the CVD reactor, and a CVD method is widely employed in which the glass main raw material and the vapor gas of the dopant raw material are oxidized or hydrolyzed.

Especially when manufacturing optical fibers with high silica content glass cores containing rare earths, for example, solid rare earth chelates as dopant raw materials with inert, non-volatile granulation such as high purity SiO ₂ or Al ₂ O ₃ It has been proposed to mix with solids, heat the mixture to a constant temperature, and vent a controlled amount of carrier gas between the mixture particles to produce the expected vapor pressure of the rare earth chelate (Patent Literature). 1, see page 4, lower left column).
In this case, a chemical reaction occurs when the evaporated rare earth chelate passes through the reaction zone formed by the oxyhydrogen flame in the CVD reactor, and the rare earth oxide of the product is traversed along with other non-volatile oxides. These components are mixed in a soot deposition layer formed on the wall surface of the glass tube downstream of the burner, and these components melt to form a glass layer when the burner passes therethrough (Patent Documents 1 and 6). (Bottom left column).

  As a practical example of a glass body containing an additive, for example, there is an optical waveguide made of silica-based glass to which a rare earth element such as Er is added. When an excitation light is incident, the energy order of rare earth ions is excited. Therefore, since it exhibits an amplification effect by stimulated emission, it is used as an optical amplifier. If an optical fiber having a rare earth element-doped core is used as an amplifier, there are advantages such as easy connection to a transmission fiber and low polarization dependence of amplification, and the CVD (particularly MCVD) method uses such a rare earth element. It is also used as a method for producing an optical glass body doped with.

JP-A-63-260835

  By the way, in the method of heating the raw material which is solid at room temperature such as the above-mentioned rare earth chelates and supplying it to the reaction system as the dopant raw material of the glass body, the vapor pressure of the dopant raw material is low, so the evaporation method is devised. It is necessary and the device becomes complicated. In particular, as seen when using a solid organometallic compound such as a rare earth chelate as a dopant raw material, the evaporation temperature is close to the melting point depending on the type of organometallic compound used. There is a problem that the surface area varies and the amount of evaporation of the organometallic compound varies with time.

The organometallic compound raw material is left as it is or is supported on an inert, non-volatile granular solid (inert solid) and heated at a temperature that does not melt it, and evaporates from the surface of the solid organometallic compound raw material. In the conventional method, the amount of the supply of the organometallic compound raw material is likely to vary with time, and it is difficult to increase the absolute supply of the organic metal compound raw material vapor. It was.
Furthermore, in the method in which the organometallic compound raw material is mixed with the inert solid or supported on the inert solid, impurities are easily mixed into the raw material, resulting in a decrease in the purity of the organometallic compound raw material such as a rare earth chelate compound and a melting point. In addition, since the vaporization temperature is affected by the sublimation temperature and the like, there is a problem that the vapor of the vaporized organometallic compound raw material cannot be stably supplied.

  Therefore, the present invention eliminates the problems of the above-mentioned conventional method, and particularly in a method for producing a glass body by heating, evaporating and supplying a dopant raw material composed of a solid-state organometallic compound to cause an oxidation reaction. An object of the present invention is to provide a method for producing a glass body, which can increase the amount of vaporization of the dopant material as compared with the method and can stably maintain the supply amount of the gasified dopant material for a long time.

The above object can be achieved by the following inventions or aspects.
(1) A method in which a glass main material and an organometallic compound are vaporized and supplied to a reaction zone, and a glass body is formed by reacting the glass main material and the organometallic compound, respectively. A method for producing a glass body, characterized in that the organometallic compound is heated and kept at a temperature above the temperature at which the liquid phase of the organometallic compound appears and vaporized.
(2) The method for producing a glass body according to (1), wherein the vapor pressure of the organometallic compound at the heating and holding temperature is 10 Pa or more.

(3) The method for producing a glass body according to (1), wherein the temperature at which the liquid phase of the organometallic compound appears is 60 ° C. or higher.
(4) The method for producing a glass body according to (1), wherein the temperature to be heated and held is lower than the decomposition temperature of the organometallic compound.
(5) The method for producing a glass body according to any one of (1) to (4), wherein a deviation of the temperature to be held by heating is within ± 1 ° C.

(6) The method for producing a glass body according to any one of (1) to (5), wherein the vaporized organometallic compound is supplied to the reaction zone together with a carrier gas.
(7) The method for producing a glass body according to (6), wherein the organometallic compound is in a liquid phase, and the carrier gas is brought into contact with the liquid phase of the organometallic compound.
(8) The method for producing a glass body according to (7), wherein the carrier gas is brought into contact with the organometallic compound for 1 second or longer.

  According to the method for producing a glass body of the present invention, (1) since the organometallic compound is heated and held in a liquid state and vaporized, the amount of evaporation is stable over time, and the characteristics of the glass body obtained are ) Since the organometallic compound is heated and held to a temperature at which the liquid phase appears, the vapor pressure of the organometallic compound is high, the amount of steam supply per hour can be increased, and the time required for production is shortened. (3) Organic Since it is not necessary to devise special measures for the evaporator of the metal compound, there is a low possibility that impurities are mixed into the raw material, and the cost of the manufacturing apparatus is reduced.

The method for producing a glass body according to the present invention comprises a step of heating a solid organometallic compound raw material (hereinafter referred to as an organometallic compound raw material or simply referred to as an organometallic compound) used as a dopant material. The glass main raw material and the organometallic compound raw material are vaporized except that they are heated and held above the temperature at which at least a part of the compound melts and the liquid phase appears, and are supplied to the reaction zone of the glass body production apparatus. This is the same as the conventional method for producing a glass body by CVD, which is supplied to the reaction zone and subjected to oxidation reaction or hydrolysis.
In the glass body manufacturing method of the present invention, an organometallic compound such as a rare earth chelate is heated in an evaporator as shown in FIG. 1, for example, and a carrier gas such as helium (He) is passed through the evaporator. Thus, the organometallic compound is evaporated and vaporized from the liquid surface of the organometallic compound at least partially liquefied or from the liquid.

  The evaporator is filled with a solid-state organometallic compound and heated by a heating means such as a heater attached around or inside the evaporator. The surface temperature of the reaction zone (heating zone) in the CVD reactor placed downstream of the evaporator and the path leading to it is sufficient to prevent condensation of evaporated organometallic compounds and vapors of the main glass material. It is necessary to maintain the temperature at such a high level that the decomposition of the organometallic compound can be suppressed (for example, 160 to 450 ° C.).

The heating of the organometallic compound is desirably performed at a temperature at which the vapor pressure is 10 Pa or more, and more preferably 50 Pa or more, and further preferably 100 Pa or more in that the amount of vaporization of the resulting organometallic compound can be further increased. Is recommended. Further, as the organometallic compound, a substance having a temperature at which the liquid phase appears when it is heated is preferably 60 ° C. or higher.
The heating and holding temperature of the organometallic compound is preferably equal to or lower than the decomposition temperature of the organometallic compound to be used, and depending on the type of the organometallic compound, heating is particularly performed at a temperature of 300 ° C. or less in order to prevent the decomposition of the compound. Is more preferable. And it is desirable to make the heating temperature for vaporizing the organometallic compound as constant as possible, and the deviation of the heating temperature (the fluctuation range of the temperature within the time of manufacturing the glass body) is within ± 1 ° C., especially It is preferable to control the temperature to be within ± 0.5 ° C. in order to stably obtain an organometallic compound vapor. Of course, it is also preferable for the entire evaporator to have a small temperature deviation depending on the location.

The vapor of the organometallic compound evaporated and vaporized as described above is supplied to the reaction zone of the CVD apparatus together with the carrier gas, and is supplied separately by vaporizing the main glass raw material to be separately supplied and, if necessary, vaporized. It is mixed with a dopant raw material other than the organometallic compound and heated to form a glass body. A rare gas is preferably used as the carrier gas, and a He gas having a high thermal conductivity is particularly preferably used as the carrier gas.
When vaporizing a solid organometallic compound, it is necessary to heat the organometallic compound at as high a temperature as possible in order to increase the vapor amount of the vaporized organometallic compound. In addition, it is preferable to heat to a temperature at which the organometallic compound is completely in a liquid phase in that the amount of evaporation of the organometallic compound can be made more uniform. Therefore, the organic metal compound in the solid phase is completely in the liquid phase, and more organic metal compounds can be vaporized uniformly by heating and holding to a temperature at which decomposition does not occur.

  Further, in order to increase the amount of evaporation and vaporization of the organometallic compound and to stably supply the gas in which the organometallic compound has evaporated and vaporized for a long period of time, it is simply heated and held until the organometallic compound is in a liquid phase state. In addition, the carrier gas is passed through the organometallic compound in the liquid phase to bring the organometallic compound in the liquid phase into contact with the carrier gas, and the vapor gas of the organometallic compound is liquidized together with the carrier gas. It is preferable to remove (convey) sequentially from the phase surface. In that case, the liquid metal-organic compound and the carrier gas, such as bubbling by bubbling the carrier gas into the liquid organic metal compound, If the contact area is made as large as possible, the vaporization of the organometallic compound is further promoted, and the evaporation and vaporization amount of the organometallic compound becomes more uniform. Masui. The liquid phase of the organometallic compound and the carrier gas are preferably brought into contact with each other for at least 1 second, preferably 2 seconds or more, and more preferably 5 seconds or more, in order to sufficiently perform evaporative gasification.

In the method for producing a glass body of the present invention, the organometallic compound that can be used is preferably a material that is solid at room temperature but has a high vapor pressure even at a relatively low temperature. An example of such a material is an organic metal (dopant). Compounds. If metal (dopant) is a rare earth, for _{example, Trisdipivaloylmethanatoerbium {Er (C 11 H} 19 O 2) 3, hereinafter, Er (DPM) _{3 abbreviated}, Trisacetylacetonatoerbium {Er (C 5} H 7 O 2) 3, or less , Er (AcAc) ₃ }, Trismethylcyclopentadienylerbium {(CH ₃ C ₅ H ₄ ) ₃ Er, hereinafter abbreviated as MeCp ₃ Er}, and the like are particularly preferably used. Other examples of the organic compound whose metal is not a rare earth include Pb (DPM) ₂ , Bi (DPM) ₃ , and Tantalium pentaisopropoxide {Ta (OiPr) ₅ }.

For example, when producing a preform for an optical fiber by the method of the present invention, the organometallic compound (volatile rare earth compound) vaporized as described above, and GeCl ₄ , BCl ₃ , POCl used as necessary. The vapor component of the dopant raw material other than the organometallic compound such as ₃ is, for example, together with inert gases such as He and Ar, O ₂ gas, and N ₂ gas used in conventional CVD methods such as the MCVD method and the PCVD method. Supplied with SiCl ₄ source gas, which is the main raw material for the separately formed porous glass layer, is supplied to the glass tube, and the burner is moved at a constant speed in the axial direction of the glass tube while heating the glass tube surface with an oxyhydrogen burner. After forming the glass layer on the inner wall surface of the glass tube and depositing the core layer, the glass tube is collapsed to form the organometallic compound and other materials used as required. Rods having a core dopant is added is formed. Further, if necessary, a clad layer may be formed prior to the formation of the core layer, or a layer containing no rare earth element or the like may be formed.

EXAMPLES Next, although an Example demonstrates this invention, this invention is not limited by this.
[Example 1]
As shown in FIG. 1, an evaporator 1 having an inner diameter of 50 mmφ and a volume of 300 cc is filled with 30 g of Er (DPM) ₃ powder, which is an organic compound of erbium (Er), as an organometallic compound 2, and a heater The evaporator 1 is heated to 200 ° C. (not shown). When the powder of Er (DPM) ₃ in the evaporator 1 is dissolved and becomes completely in a liquid phase state, the carrier gas from the gas inlet pipe 3 on the inlet side of the evaporator 1 is brought to substantially the same temperature as the evaporator 1. Then, 50 sccm of separately heated He gas is allowed to flow, and the gas containing vaporized Er (DPM) ₃ flowing out from the gas outlet pipe 4 on the outlet side of the evaporator 1 is guided to the cooling pipe and trapped. over time to measure the amount of evaporation of Er (DPM) ₃ in the carrier gas per unit volume by quantifying the Er (DPM) ₃ of effluent gas at time intervals of. Further, the remaining amount of Er (DPM) ₃ in the evaporator 1 at each time point when the evaporation amount of Er (DPM) _{3 in} the gas flowing out from the outlet side 4 of the evaporator 1 was measured as described above. In parallel, measure each time.

The remaining amount of Er (DPM) ₃ , which is the organometallic compound 2 in the evaporator 1, and the amount of evaporation of Er (DPM) _{3 in} the unit volume of the carrier gas evaporated from the evaporator 1 are obtained as described above. The relationship is shown by curve a in FIG. Note that the evaporation amount (vertical axis) of Er (DPM) ₃ in FIG. 5 is a relative value normalized by the evaporation amount (initial evaporation amount) of Er (DPM) ₃ in the carrier gas first measured as described above. Value.
Next, the vapor of the organometallic compound 2 {Er (DPM) ₃ } obtained as described above is transported to the reaction zone of the CVD reactor together with the carrier gas, and the reaction zone is supplied together with the vapor of the main glass material supplied separately. The glass body is produced by mixing and heating with a conventionally known method. The obtained glass body having a length of 500 mm has a region with a diameter of about 2.5 mmφ, which is quartz glass with an Er added at the center, and the average Er concentration in the region is 600 ppm by weight, in the longitudinal direction of the glass body. The variation of the Er concentration over the range is within ± 0.5% of the average value, and the variation is small.

[Example 2]
As shown in FIG. 2, when the evaporator 11 filled with the organometallic compound 12 is heated and the entire organometallic compound 12 is in a liquid phase, a liquid phase liquid composed of the organometallic compound 12 is obtained. Example 1 using the evaporator 11 having the same inner diameter and volume as Example 1 except that the gas inlet pipe 13 on the inlet side of the evaporator 12 is arranged so that the opening end portion comes below the surface. and Er (DPM) ₃ of the remaining amount in the evaporator 11 in the same manner as, the evaporator 11 evaporates from flowing out together with the carrier gas from the outlet side of the gas outlet pipe 14 of the evaporator 12 Er (DPM) ₃ The relationship with the amount of evaporation in the unit volume of the carrier gas was determined. The result is shown by curve b in FIG. Note that the evaporation amount (vertical axis) of Er (DPM) ₃ in FIG. 5 is all relative values normalized by the initial evaporation amount in the case of the first embodiment.

[Comparative Example 1]
As shown in FIG. 3, a mesh-like organometallic compound mounting shelf 25 is provided in the evaporator 21 having the same inner diameter and volume as in the first embodiment, substantially parallel to the bottom surface, and the organometallic compound 22 is provided thereon. As in Example 1, the same amount of Er (DPM) ₃ powder is placed, and the open end of the gas inlet pipe 23 on the inlet side of the evaporator 21 extending below the organometallic compound placement shelf 25 from the case and the evaporator 21 while flowing the same amount of He gas (carrier gas) was melted Er (DPM) ₃ and 160 ℃ {Er (DPM) ₃ example 1 than the temperature at which the liquid phase appears It is heated at a low temperature} to evaporate the organometallic compound 22, and Er (DPM) ₃ gas flowing out from the gas outflow pipe 24 on the outlet side of the evaporator 21 together with He gas is guided to the cooling pipe and trapped. In the same way as in Example 1, outflow gas at regular time intervals The solution of Er (DPM) ₃ amount and the remaining amount of Er (DPM) ₃ in evaporator 21 was quantified, and the remaining amount of Er (DPM) ₃ in the evaporator 21, the carrier gas evaporated from the evaporator 21 The relationship with the evaporation amount of Er (DPM) _{3 in} a unit volume is obtained. The result is shown by a curve c in FIG. Note that the evaporation amount (vertical axis) of Er (DPM) ₃ in FIG. 5 is a relative value normalized by the initial evaporation amount in the case of the first embodiment.

[Comparative Example 2]
Instead of providing an organometallic compound mounting shelf 25 inside the evaporator 21 and placing Er (DPM) ₃ thereon, as shown in FIG. 4, an organometallic compound 32 {Er (DPM) is formed on the surface thereof. ) The evaporator 31 was melted at 160 ° C. {Er (DPM) _{3 in the same} manner as in Comparative Example 1 except that the ceramic particles 35 made of inert alumina carrying ₃ } powder were filled in the evaporator 31. The organometallic compound raw material 32 is evaporated by heating at a temperature lower than the temperature at which the liquid phase appears}, and the gas flowing out from the gas outlet pipe 34 on the outlet side of the evaporator 31 together with the helium gas is led to the cooling pipe. The amount of Er (DPM) ₃ in the gas is quantified at a constant time interval, and the remaining amount of Er (DPM) ₃ in the evaporator 31 and the evaporation from the evaporator 31 are determined in the same manner as in the first embodiment. Er (DPM) Determining the relationship between the _third evaporation. The result is shown by a curve d in FIG. Note that the evaporation amount (vertical axis) of Er (DPM) ₃ in FIG. 5 is a relative value normalized by the initial evaporation amount in the case of the first embodiment.

  As can be seen from FIG. 5, the organic metal compound in the solid phase is heated to a temperature equal to or higher than the temperature at which the organometallic compound melts and the liquid phase appears, and at least a part of the organic metal compound is in the liquid phase. When the carrier gas is brought into contact with the metal compound (in the case of curves a and b), the organic metal is compared with the case in which the carrier gas is brought into contact with the solid-state organometallic compound (in the case of curves c and d). The amount of evaporation of the compound increases and the amount of evaporation stabilizes for a long time.

  Further, even when the organometallic compound is melted and brought into contact with the carrier gas in the liquid phase state, the liquid phase state is more than the case where the carrier gas is simply brought into contact with the surface of the organometallic compound in the liquid phase state (in the case of curve a). When the carrier gas is bubbled through the inside of the organometallic compound (in the case of curve b), the contact area between the organometallic compound and the carrier gas increases, and the amount of evaporation of the organometallic compound is further improved. As a result, the organometallic compound was evaporated by the conventional method (the method as exemplified in Comparative Examples 1 and 2) by evaporating the organometallic compound by the method of the present invention (the method as exemplified in Examples 1 and 2). Compared with the case where the vapor is evaporated, a large amount of the vapor of the organometallic compound can be stably obtained, and a glass body having stable characteristics can be produced in a short time.

It is a schematic diagram which shows the one aspect | mode of the state equipped with the supply and discharge system of the carrier gas filled with the organometallic compound used in the manufacturing method of the glass body of this invention. It is a schematic diagram which shows another aspect of the state equipped with the supply and discharge system of the carrier gas filled with the organometallic compound used in the glass body manufacturing method of the present invention. It is a schematic diagram which shows the one aspect | mode of the state equipped with the supply of the carrier gas filled with the organometallic compound, and the discharge system used in the manufacturing method of the conventional glass body. It is a schematic diagram which shows another aspect of the state equipped with the supply of the carrier gas filled with the organometallic compound, and the discharge system used in the manufacturing method of the conventional glass body. It is a graph which shows the change of the evaporation amount per unit time of the organometallic compound with time in the manufacturing method of the glass body of the present invention, and the manufacturing method of the conventional glass body.

Explanation of symbols

1, 11, 21, 31 Evaporator 2, 12, 22, 32 Organometallic compound 3, 13, 23, 33 Gas inflow pipe 4, 14, 24, 34 Gas outflow pipe 25 Organometallic compound mounting shelf 35 Ceramic particles

Claims (8)

A glass main material and an organometallic compound are vaporized and supplied to a reaction zone, and the glass main material and the organometallic compound are respectively reacted to form a glass body, which is a solid phase at room temperature. A method for producing a glass body, characterized in that an organometallic compound is heated and held above a temperature at which a liquid phase of the organometallic compound appears and is vaporized and supplied. The method for producing a glass body according to claim 1, wherein the vapor pressure of the organometallic compound at the temperature to be heated is 10 Pa or more. The method for producing a glass body according to claim 1, wherein the temperature at which the liquid phase of the organometallic compound appears is 60 ° C or higher. The method for producing a glass body according to claim 1, wherein the temperature for heating and holding is lower than the decomposition temperature of the organometallic compound. The glass body manufacturing method according to any one of claims 1 to 4, wherein a deviation of the temperature to be held by heating is within ± 1 ° C. The method for producing a glass body according to any one of claims 1 to 5, wherein the vaporized organometallic compound is supplied to the reaction zone together with a carrier gas. The method for producing a glass body according to claim 6, wherein the organometallic compound is in a liquid phase, and the carrier gas is brought into contact with the liquid phase of the organometallic compound. The method for producing a glass body according to claim 7, wherein the carrier gas is brought into contact with the organometallic compound for 1 second or longer.

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