JPS63236729A - Production of chalcogenide glass fiber having core clad structure - Google Patents

Abstract

PURPOSE:To prevent occurrence of oxidation and devitrification of glass in spinning and promote formation of a fiber having a core clad structure and excellent infrared transmitting properties, by adopting a specific constitution in a spinning method in producing a chalcogenide glass fiber by a double crucible method. CONSTITUTION:A chalcogenide glass rod 3 is inserted into the inner crucible 1 of a cylindrical double crucible having a spinning nozzle at the bottom thereof and a chalcogenide glass tube 4 having a higher refractive index than that of the chalcogenide glass rod 3 is inserted into the outer crucible 2. The interior and exterior of the crucibles 1 and 2 are kept in an inert gas atmosphere (a gas is fed from inert gas inlets 7, 8 and 9) to heat only the tube 4 and rod 3 near the spinning nozzle at a higher temperature than glass transition temperature (with a heater 11) to simultaneously take out the glass tube 4 and glass rod 3 from the spinning nozzle of the crucible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a chalcogenide glass fiber having a core-clad structure with excellent infrared transparency.

[Prior Art] Chalcogenide glass is a material for infrared fibers with excellent infrared transparency and weather resistance, and many glass compositions have already been reported (for example, Z, U, etc.).

Borisova, Glassy Sem1cond
uctor Plenumpress.

New York, 1981). Among these chalcogenide glass compositions, those that can transmit light in the wavelength range of around 10μ, that is, in the wavelength range of carbon dioxide laser beams, with low loss are Ge-glasses with a Te content of 50 mol% or more.
3e-Te system, and its fiberization is being considered (for example, Toshio Katsuyama, Hiroyoshi Matsumura, Proceedings of the Institute of Electronics and Communication Engineers National Conference (March 1985) p4-256).

However, glass fibers with a high Te content have low mechanical strength, so they are of little practical use unless they are reinforced with a resin coating or the like. However, since the wavelength around 10 μm is the fingerprint region of various resin materials, infrared rays in that wavelength region are absorbed. Therefore, it is not possible to directly coat the outer periphery of chalcogenide glass fibers with such a resin material.

This problem is solved by using chalcogenide glass fiber as the core.
This problem can be solved by creating a double clad structure and then coating the outer periphery with resin. The double crucible method is known as a method for producing glass fibers with a core-clad structure (Teruhisa Kanamori et al., Telecommunications Research Institute,
Research Practical Report, 32 (1983), 2737). This method involves inserting the core glass into an inner crucible and the cladding glass into an outer crucible, melting them, and simultaneously extruding both glasses from a spinning nozzle installed at the bottom of the double crucible to form fibers. It is. However, as mentioned above, chalcogenide glass systems with a high Te content of 50 mol% have low thermal stability against crystallization, and chalcogenide glass systems that contain components with high vapor pressure such as As and se, Since compositional fluctuations occur due to evaporation of glass components at high temperatures, it is difficult to regularly produce chalcogenide glass fibers with a two-arc clad structure using the double crucible method described above.

In addition, as a manufacturing method for glass fiber with a core-clad structure, there is a rod-in-tube method in which a core O-rad-shaped glass is inserted into a tube-shaped glass cladding, and its tip is melt-spun. , traditionally used in the production of quartz glass fibers. However, the viscosity of chalcogenide glass fluctuates significantly even with slight temperature changes, and its spinning must be carried out in a non-oxidizing atmosphere, so the rod-in-tube method cannot be used as is for producing chalcogenide glass fibers.

[Problems to be solved by the invention] As mentioned above, even if the conventional rod-in-tube method or double crucible method is directly applied to chalcogenide glass,
Since glass oxidation and devitrification occur during spinning, the desired infrared transparent glass fiber cannot be obtained. The present invention is a new glass fiber manufacturing method that eliminates the problems of oxidation and devitrification that are a concern when spinning chalcogenide glass, and makes it possible to manufacture fibers with a core-clad structure with excellent infrared transparency from chalcogenide glass. I will provide a.

[Means for Solving the Problems] The glass fiber manufacturing method according to the present invention includes a cylindrical double crucible having a spinning nozzle at the bottom, a chalcogenide glass rod in the inner crucible, and a chalcogenide glass rod in the outer crucible having a refractive index higher than that of the glass rod. Insert a chalcogenide glass tube with a low temperature, maintain the inside and outside of the crucible in an inert gas atmosphere, and heat only the tube and rod near the spinning nozzle to a temperature higher than the glass transition temperature. At the same time, a chalcogenide glass fiber having a core-clad structure is obtained by drawing it out from the spinning nozzle of the crucible.

[Function] In the method of the present invention, when heating the glass tube and glass rod located near the spinning nozzle, the inside of the double crucible and the vicinity of the nozzle on the outer periphery of the crucible are sufficiently replaced with inert gas in advance. It is desirable to leave it there. If this replacement is insufficient, the glass tube and glass rod may be corroded by water vapor and oxygen during heating. Heating is performed by keeping the interior of the double crucible and the vicinity of the spinning nozzle of the crucible in an inert gas atmosphere, and locally heating the glass tube and glass rod located near the spinning nozzle, so that these are heated to a temperature higher than the glass transition temperature. After being fluidized, the material is immediately spun by the gas pressure in the crucible and/or the load applied to the glass tube and glass rod. Therefore, the glass is not attacked by oxygen during the spinning process, and the fibers are not cut. Furthermore, since the glass is not exposed to temperatures above the glass transition temperature for a long period of time, there is no fear that the glass will devitrify.

The heating temperature is 103~ for glass tubes and glass rods.
It is preferable that the temperature range is such that the viscosity can be maintained within the range of 108 poise. When the viscosity of the glass is lower than 103 voices, the tendency of both glasses to devitrify increases, and the circularity of the resulting fiber may decrease. Furthermore, if the viscosity of the glass is higher than 108 poise, the glass becomes difficult to viscous flow, so the crucible internal pressure and/or load required for spinning must be increased, which makes it difficult to control the fiber diameter. Moreover, the drawing speed during spinning becomes slow, resulting in a decrease in productivity.

The glass tube and glass rod located near the spinning nozzle are heated to the above temperature range, and are simultaneously spun from the spinning nozzle. In this case, the glass tube and the glass rod can be spun using their own weight alone without applying any special load, but if the viscosity of the glass tube and the glass rod at the heating temperature is different, the viscosity difference By pressurizing the internal pressure of the inner crucible and the internal pressure of the outer crucible with inert gas, depending on the By applying pressure, the spinning temperature can be lowered and devitrification of the glass can be suppressed during spinning. However, even in that case, the inert gas pressure is 5k (J/
i, preferably in the range of 0.1 to 3 kMcd; excessive pressure exceeding 5 ka/d makes it difficult to control the fiber diameter and reduces the circularity of the fiber.

In addition, if the viscosity of the glass tube and glass rod at the heating temperature is significantly different, or if you want to strictly control the ratio of the core diameter to the cladding diameter of the resulting fiber, it is possible to separate It is effective to apply a load. However, if too much load is applied, there is a risk that the glass tube or glass rod may be destroyed, and control of the fiber diameter becomes difficult, so it is appropriate that the upper limit of the load be about 10 k(+/li).

[Example 1] Next, the method of the present invention will be explained in more detail based on an example.

Example 1 A chalcogenide glass fiber having a core-clad structure was manufactured according to the method of the present invention using an apparatus having the configuration shown in FIG.

First, the upper part of the device was removed from the lower part at the flange 18, and Ge: 25 mol%, Se: 13 mol%, T
Composition: e: 60 mol%, Tl: 2 mol%, diameter: 9.
5#, length 120I1m++ core glass rod 3
, Ge: 24 mol%, Se: 16 mol%, Te:
Composition of 60 mol%, inner diameter 13I1m1 outer diameter 17.5I
1m, length 120am glass tube for cladding 4
were vertically housed in an inner crucible 1 and an outer crucible 2 of a double crucible equipped with a spinning nozzle at the bottom, as shown in FIG.

After applying a load of 1 m-A of 5 kg/cd to the glass rod 3 and a load of 20 kg/ci to the glass tube 4, the flange 18 was closed via the pressure-resistant rubber tube 16 and the rubber packing 11, and the double crucible was closed. The inside and the outer periphery of the tank were sufficiently replaced with argon gas.

Thereafter, the inert gas lower door 8 into the double crucible is closed, and the temperature of the heater 11, which can locally heat only the vicinity of the spinning nozzle of the double crucible, is gradually raised to 285°C. This temperature rise fluidizes the tips of the glass tube and glass rod inside the crucible, so the inside crucible 1 is heated with inert gas.
Inside crucible 2 to 0.5kMcd and outside crucible 2 to 0.8! Pressure was applied to II/cIi, and the fluidized glass tube and glass rod were simultaneously pulled out from the spinning nozzle at the bottom of the crucible. The fiber thus obtained is immediately introduced into the coater 12 to coat the fiber with an ultraviolet curing resin 13, and then the resin is cured with an ultraviolet lamp 14 to form a core with a diameter of 420μ and a cladding with a diameter of 550μ.
μm.

A chalcogenide glass fiber with a resin coating thickness of 30 μm and a length of 20 m was obtained. FIG. 2 shows the wavelength dependence of the transmission loss value of this fiber. Further, the glass composition of the fiber, spinning conditions, and minimum transmission loss value are summarized in Table 1.

Examples 2 to 4 Core-clad chalcogenide glass fibers were prepared in the same manner as in Example 1, except that the glass composition and spinning conditions were changed as shown in Table 1. Table 1 shows each fiber diameter, spinning conditions, minimum transmission loss value, and its wavelength.

Comparative Example 1.2 Only the glass rod used for the core in Examples 1 and 4 was used as the first
A resin clad fiber was produced in the same manner as in Example 1 except that the fiber was placed in the inner crucible 1 of the apparatus shown in the figure and the glass tube was not used.

The spinning conditions and fiber diameter in this case are also shown in Table 1.

Further, the wavelength dependence of the transmission loss value of the resin clad fiber obtained in Comparative Example 1 is shown in FIG. As is clear from Figure 2, the resin clad fiber has a wavelength of 5 to 11μ.
Since absorption by the resin occurred in the region I, the transmission loss value increased by about 5 dB/a+.

[Effects] According to the method of the present invention, core-clad chalcogenide glass fibers, which could not be produced by conventional rod-in-tube methods or double crucible methods, because they are not stable against crystallization, can be produced by It can be manufactured without oxidation or devitrification of glass.

Furthermore, since the core-clad type chalcogenide glass fiber does not lose its infrared transmittance even if it is coated with resin, the method of the present invention is extremely useful in increasing the practicality of chalcogenide glass fiber. .

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a fiber manufacturing apparatus used in an example of the present invention. FIG. 2 is a graph showing the wavelength dependence of the transmission loss values of the glass fibers obtained in Example 1 and Comparative Example 1. 1: Inner crucible 2: Outer crucible 3: Glass rod for core 4: Glass tube for cladding 5: Load-A 6: Load-B7: Inert gas inlet for pressurizing inner crucible 8: Inert gas inlet for pressurizing outer crucible 9 Inert gas for controlling the atmosphere around the nil acupoint 10 Inert gas outlet for controlling the atmosphere around the nil acupoint 11: Heater for local heating 12: Coater 13: Ultraviolet curing resin 1
4: Ultraviolet lamp 15 Niblin troller 16: Pressure-resistant rubber tube 17: Rubber gasket 18: Flange Non-oxide Glass Research and Development Co., Ltd. Agent Masayuki Asakura Figure 2 Wavelength (μm)

Claims (1)

[Scope of Claims] 1 A chalcogenide glass rod is inserted into the inner crucible of a cylindrical double crucible having a spinning nozzle at the bottom, and a chalcogenide glass tube having a lower refractive index than the glass rod is inserted into the outer crucible, and the inside of the crucible and A core characterized in that the outside of the crucible is maintained in an inert gas atmosphere, and the glass tube and glass rod are simultaneously pulled out from the spinning nozzle of the crucible while heating only the tube and rod near the spinning nozzle to a temperature higher than the glass transition temperature. −
A method for producing a chalcogenide glass fiber having a cladding structure. 2 The heating temperature of the tube and rod is 10^3
The method according to claim 1, characterized in that the temperature is such that the viscosity can be maintained at a viscosity of ~10^8 poise. 3. The method according to claim 1, wherein when heating the tube and rod in the crucible, the inside of the inner crucible and the inside of the outer crucible are independently pressurized with an inert gas. 4. The method according to claim 3, wherein the pressure of the inert gas in the crucible is 5 kg/cm^2 or less. 5. The method according to claim 1 or 3, characterized in that when heating the tube and rod in the crucible, a load is applied to the upper ends of the tube and rod, respectively. 6 The load applied to the upper end of the tube and rod is 10 kg.
6. The method according to claim 5, characterized in that it is less than /cm^2.