JP2003246642A - Glass and optical fiber using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass which is less liable to crystallize even when reheated to its glass transition temperature or above because thermal latitude is largely extended in spite of a high phosphate content, enhances the yield of working such as fiber formation and obtains required characteristics, and to provide an optical fiber using the glass. <P>SOLUTION: The phosphate-rich glass containing ≥38 mol% diphosphorus pentoxide is made less liable to crystallize by lowering crystallization calorific value in the glass to ≤60 J/g and enhancing thermal stability as glass, even when the glass is held at a temperature close to its crystallization temperature in working accompanied by reheating to its glass transition temperature or above, a longer time can be ensured before perfect crystallization, conditions in working such as optical fiber formation can be greatly mitigated and working into an optical fiber or the like is reliably carried out while exhibiting the features of phosphate glass. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass having a high phosphate content, and more particularly to a glass that is not easily affected by crystallization during manufacturing and fiber processing, and an optical fiber formed from the glass.

[0002]

2. Description of the Related Art In recent years, optical fibers have been used in a wide range of fields centered on optical communication. Most of the commonly used optical fibers are of the so-called silica glass type. For example, a preform is produced by a flame deposition method, and then this preform is heated and stretched at a high temperature to obtain a fiber. The quartz glass used for this optical fiber is
In addition to having high transparency and good transmission characteristics, it has the features of being stable and excellent in weather resistance, while having a high melting temperature,
It had to be manufactured and processed at high temperatures, and it was easily affected by birefringence.

On the other hand, phosphate glass is an excellent solvent for basic oxides due to the action of double bonds contained in its structure, and its melting temperature is lower than that of quartz glass, so that it solidifies. Rayleigh scattering, which is dependent on the density fluctuation of H., is small and has low photoelasticity, and has recently attracted attention as a glass material for optical elements such as lanthanoid-doped glass elements and optical fibers. I am collecting. When forming an optical fiber type element with this phosphate glass, it is desirable to increase the phosphate content in the glass in order to bring out the excellent material properties of the phosphate glass. In some cases, it is desirable to set the content of the specific network modifying oxide together with the phosphate to be high at the same time. When manufacturing an optical fiber with non-quartz glass such as phosphate glass, or so-called multi-component glass composed of a plurality of elements other than quartz, use the flame deposition method similar to the above quartz glass. However, the rod-in-tube method and the double crucible method in which fibers are directly formed from the melt were used.

Of these, when trying to obtain an optical fiber after producing a preform by the rod-in-tube method,
It is necessary to heat the outer periphery of the preform to a proper temperature with a heater and draw it into a fiber shape. However, glass generally has a property of crystallizing when heated to a crystallization temperature, and when crystallized, excellent properties of glass such as fluidity disappear, so that a fiber that positively utilizes such properties is used. Processing becomes extremely difficult, and continuous fiberization becomes impossible. For this reason, various methods have been proposed in which the composition of glass and the manufacturing method are devised so that the temperature for crystallization does not reach the crystallization temperature during heating to avoid crystallization and the fiber is formed.

[0005]

Although the conventional fiberization of glass has been carried out as described above, the glass having a high phosphate content is not crystallized by reheating to a glass transition temperature or higher. The temperature range that can be crystallized is narrow, and even if the temperature is lower than the crystallization temperature, it may crystallize if held for a certain period of time. There is a high risk that crystals will precipitate and the entire fiber will become defective.

In the fiber manufacturing process of phosphate glass, the preform has to be heated from the outer periphery by a heater, but the glass has poor thermal conductivity, and the central portion of the preform is harder to heat up than the outer peripheral portion and the temperature is high. Low. vice versa,
When the center of the preform is sufficiently heated, the outer peripheral portion is kept at a temperature higher than that of the center for a long time. This difference in the heating state becomes more remarkable as the diameter of the preform becomes thicker, and if the diameter of the preform is 10 mmφ, it can be made into a fiber without crystallization of the outer peripheral portion, but if it becomes a practical size of about 50 mmφ, the central portion becomes Crystallization occurs at the outer periphery of the preform where the temperature is significantly higher than that of the amorphous form, and amorphous and crystalline parts are mixed to cause deformation of the preform, making stable and continuous fiber formation difficult. Even if it could be made into a fiber, there was a problem that it would be in a state of containing fine crystals and the designed characteristics could not be exhibited. Since the problem of crystallization strongly depends on the temperature and the holding time, it is possible to solve this problem if strict temperature control can be realized in the fiber manufacturing process, but it is necessary to put such a manufacturing process into practical use. Had a problem that it was costly and difficult to realize.

On the other hand, in a general optical fiber, the volume of the clad occupies most of the core and the functional surface is almost determined by the characteristics of the core. Most of is decided. Therefore, as another method for solving the problem of crystallization, it is also possible to combine a cladding of glass that is difficult to crystallize such as a phosphate-based multi-component glass and a core of a phosphate-rich glass, but in this case, Since the properties of the two are significantly different, the physical properties that can function as the core and the clad of the optical fiber are not satisfied, and there is a problem that they cannot be made into fibers or cannot be made to function as optical fibers even if they can be made into fibers.

When the glass fiber is formed by the double crucible method, the melt is rapidly cooled to reduce the influence of crystallization, but the structure of the optical fiber to be formed is discharged from the nozzle of the crucible. There is a problem that it is difficult to manufacture a single-mode fiber that requires an extremely small core portion in the fiber because the adjustment is performed by the amount.
For this reason, conventionally, it has not been possible to stably and continuously manufacture an optical fiber having at least a phosphate-rich glass in its core.

The present invention has been made in order to solve the above-mentioned problems, and it is difficult to crystallize even if it is reheated to a temperature higher than the glass transition temperature by greatly expanding the thermal tolerance while containing a high proportion of phosphate. It is an object of the present invention to provide a glass which can improve a processing yield such as fiberization and can obtain desired characteristics, and an optical fiber using the glass.

[0010]

The glass according to the present invention comprises:
It contains at least 38 mol% of diphosphorus pentoxide as a network-forming component and has a crystallization heat value of 60 J / g or less. As described above, in the present invention, the crystallization heat value in the phosphate-rich glass containing diphosphorus pentoxide in an amount of 38 mol% or more is set to 60 J / g or less to improve the thermal stability of the glass. As a result, crystallization hardly occurs, and even when the temperature is maintained near the crystallization temperature in the process involving reheating to a glass transition temperature or higher, it is possible to secure a longer time margin until complete crystallization,
Processing conditions such as optical fiber can be significantly eased, while the advantages of phosphate glass can be exhibited, processing to optical fiber etc. can be reliably performed, and stress relaxation processing time for glass can be shortened. The production conditions can be greatly eased. Further, during processing, even if there is a portion that reaches a temperature region where crystallization can be induced, the effect of surface crystallization can be alleviated, so that deformation of the material due to crystal generation can be suppressed, and adverse effects during processing Can be significantly reduced.

Further, the glass according to the present invention contains, if necessary, 0.1 mol% or more of an oxide of one or a plurality of elements of Groups 3B to 5B of the Periodic Table, and at least the electronic polarizability of ions. It has a network modifying component containing a high element, and the molar ratio of the network modifying component and the network forming component is 1.0 or more. As described above, in the present invention, the phosphorus pentoxide content is 38 mol% or more, and the network modifying component is further included.
When the composition contains an oxide of one or more elements of the B to 5B group, crystallization is less likely to occur, and
It can be a material with or very close to the features and properties of high phosphate glass.

Further, the glass according to the present invention uses, as necessary, one or a plurality of substances containing the respective elements constituting the network-modifying component and the network-forming component, as a starting material. On the other hand, as an additive material for increasing the network modifying component, a fluoride of an element having a high electron polarizability of the ion contained in the network modifying component, a fluoride and an oxide of an element having a high electron polarizability of the ion, or a predetermined fluorine A predetermined amount of an oxide of an element having high electronic polarizability of a compound and an ion is added.

As described above, in the present invention, as an additive material for increasing the proportion of the network modifying component in the vitrified state, a substance containing fluorine or an element having a high electron polarizability of ions contained in the network modifying component is added to prepare a raw material. While keeping a small amount of fluorine in the melt, by increasing the molar ratio of the network modification component, the behavior of the raw material melt at the time of production can be crystallized by being stabilized by fluorine and being transferred to the glass state. Is suppressed and a clean glass state without quality deterioration is obtained, and a glass having a large molar ratio of the network modifying component can be obtained without any trouble.

Further, in the glass according to the present invention, a predetermined gas that reacts with fluorine is blown into the raw material melt obtained by heating and melting the starting raw material so that the fluorine in the raw material melt is added to the predetermined gas. And is volatilized from the raw material melt in the state of a fluoride gas to be in a vitrified state. Thus, in the present invention, by blowing a predetermined gas that reacts with fluorine after melting the starting material to volatilize fluorine as a fluoride gas and reduce the amount of fluorine in the material melt, The adverse effects of the presence of fluorine can be suppressed, and clean, homogeneous glass can be produced.

The glass according to the present invention may have a molar ratio of the network modifying component and the network forming component of 1.
It will be 25 or more. As described above, in the present invention, the amount of the network modifying component is increased by adding a trace amount of fluorine to increase the molar ratio to 1.25 or more, and the behavior of the raw material melt at the time of production is stabilized by fluorine. By shifting to the glass state, even if there are many network modifying components, the raw material melt can be shifted to the glass state without hindrance, and crystallization hardly occurs, and by adjusting the proportion of the network modifying components appropriately, phosphorus It is possible to draw out the excellent properties of the salt glass more stably.

Further, in the glass according to the present invention, the network modifying component is barium oxide, and the oxide of a group 3B to 5B element of the periodic table is boron oxide and / or germanium oxide, if necessary. Is. As described above, in the present invention, barium oxide having a property of reducing the photoelastic constant is contained as the network modifying component, and boron oxide and / or germanium oxide is contained as an additive for reducing the heat value of crystallization. By adjusting the proportion of barium and adjusting the content of the phosphate, which is the main component, to a predetermined photoelastic constant, another glass material having a property of particularly low photoelasticity and a refractive index It is possible to obtain a material having good conformity with respect to characteristics such as coefficient of thermal expansion and softening temperature and being hard to crystallize. For example, suitable processing can be performed integrally with other glass materials as a core portion or a clad portion of an optical fiber. Furthermore, boron oxide and germanium oxide have the effects of suppressing crystallization as well as photoelastic constant and refractive index,
The thermal characteristics can be adjusted, and the characteristics according to the purpose can be appropriately set by adjusting the addition amount.

Further, the glass according to the present invention contains a predetermined amount of silicon dioxide and / or alumina, if necessary. As described above, in the present invention, silicon dioxide and / or alumina, which affects various properties of glass, is contained as an additive, and its behavior and physical properties are desired until after the transition from the raw material melt state to the glass state during production. By controlling the state, various properties such as liquidus temperature, chemical stability, photoelastic constant, refractive index, transmittance, and durability can be adjusted to improve performance.

The optical fiber according to the present invention is formed by including at least a part of the glass according to any one of claims 1 to 7. As described above, in the present invention, at least a part thereof has a crystallization heat value of 60 J.
/ G or less of the glass with a high phosphate content, and the thermal stability of the phosphate glass as a fiber material is improved, so that the outer circumference of the material is increased by the fiber-like processing accompanied by the reheating to the glass transition temperature or more. Even if the part is kept near the crystallization temperature, the time to fully crystallize can be secured longer, the processing conditions can be greatly relaxed, and the features of phosphate glass can be exhibited Shaped processing can be performed reliably and can be easily manufactured. Furthermore, each part of the fiber can have an appropriate configuration that satisfies the physical property condition that it can function as an optical fiber, and can reliably function as an optical fiber of phosphate-rich glass.

Further, in the optical fiber according to the present invention, at least the clad portion is formed of the glass, if necessary. As described above, in the present invention, of the optical fibers having the core portion and the cladding portion, the cladding portion is formed of the phosphate-rich glass having a crystallization heat value of 60 J / g or less, and the volume occupied by the fiber is large. Since the thermal stability is improved in the clad part that is most susceptible to crystallization during optical fiber manufacturing because it is located on the outer peripheral side where it is exposed to a lot of high heat, the fiber shape with reheating above the glass transition temperature Even if the cladding is kept near the crystallization temperature during processing, the time to fully crystallize can be secured longer, the processing conditions can be greatly relaxed, and fiber processing can be performed reliably and easily. Can be manufactured.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. The glass according to the present embodiment is a phosphate glass containing 38 mol% or more of diphosphorus pentoxide (P ₂ O ₅ ) as a network forming component, and its crystallization heat value is 60 J / g or less. Is. As the network modifying component in the glass according to the present embodiment, an oxide of an element having a high cation electronic polarizability among alkaline earth metals is used, and the molar ratio of the network modifying component to the network forming component is 1. The content is set to 0 or more. More preferably, barium oxide (BaO) is used as this network modification component. In addition to this, as an additive for suppressing the crystallization of glass,
An oxide of any one or more elements of Groups 3B to 5B of the periodic table is used and added so that the content in the glass is 0.1 mol% or more. More preferably, the additive is boron oxide (B ₂ O ₃ ), germanium oxide (GeO).
_Use either or both of ₂ ).

If necessary, these basic compositions are
As a substance added for chemical durability, thermal stability, refractive index adjustment, high-quality glass formation, etc., alumina (Al ₂
O ₃ ), silicon dioxide (SiO ₂ ), and the like. When these alumina and silicon dioxide are added, the content ratio in the glass is 0.1 to 6 mol% for alumina and 0.1 to 5 mol% for silicon dioxide. In addition, as another additive that gives the above effect, La
₂ O ₃ , Nb ₂ O ₅ , Sb ₂ O ₃ , Na ₂ O, Li ₂ O,
Cs ₂ O, Ta ₂ O ₅ , CaO, K ₂ O, SnO 2, T
iO ₂ , ZrO ₂ , SrO ₂ , As ₂ O ₃ , ZnO, WO
It is also possible to add ₃ , TeO ₂ or the like.

Further, when the glass having a small photoelastic constant is integrally processed, various characteristics are adapted to the glass, and the photoelastic constant is reduced while having a characteristic of being hard to crystallize. When increasing the proportion of the modifying component, a fluoride of an element having a high electron polarizability of ions contained in the network modifying component may be added. Since fluorine and alumina have the property of increasing the photoelastic constant of similar glasses, it is preferable to add as little as possible when it is desired to decrease the photoelastic constant of the glass itself.

Next, the production of the glass according to this embodiment will be described. In the production of this glass, a predetermined one or a plurality of starting materials containing the elements constituting the network-modifying component and the network-forming component are used, and the molar ratio of the network-modifying component and the network-forming component when it becomes glass is used. It is appropriately adjusted so as to have a desired ratio, and an oxide of an element of Group 3B to 5B of the periodic table is added to prevent crystallization. Further, when it is desired to increase the proportion of the network modifying component, a fluoride (for example, barium fluoride) of an element having a high electron polarizability of ions contained in the network modifying component is added, or an electron of the same ion is added together with the fluoride. An oxide of an element having a high polarizability (for example, barium oxide) may be added, or a fluoride of another predetermined element may be added together with the oxide of an element having a high electron polarizability of the ions.

When the starting material and the additive material are melted in the crucible, fluorine generated from the added fluoride is present in the material melt. When, for example, moist air is blown into the raw material melt as the predetermined gas and the water in the air is reacted with fluorine in the raw material melt, the fluorine becomes hydrogen fluoride. By volatilization of the hydrogen fluoride from the raw material melt, only fluorine is reduced from the raw material melt. After that, the raw material melt is stirred,
Glass is obtained by homogenizing by aeration and cooling in a mold.

Oxides of Group 3B-5B elements of the Periodic Table, especially
By adding boron oxide and germanium oxide, which have a great effect of reducing the heat generation amount, to the phosphate glass, the heat generation amount for crystallization of the glass is reduced to 60 J / g or less. The fact that the heat of crystallization of glass is as small as 60 J / g or less means that the thermal stability of the glass is increased in the temperature range of the glass transition temperature or higher when the temperature is raised at a predetermined heating rate, that is, , Shows that the ratio of the glass that remains as glass without crystallization is increasing, and when the temperature is raised at the predetermined heating rate, crystallization occurs when the glass is kept for a predetermined time at or above the glass transition temperature. Even in the fiber processing temperature range where it is likely to occur, the glass softens and melts without crystallizing. Therefore, the glass can be made into a fiber without being crystallized.

The crystallization generally occurs depending on the heating time when the glass is heated at a temperature higher than the glass transition temperature, but the behavior varies depending on the glass material.
As a means for comparison, for example, a method such as DSC (differential scanning calorimetry) or DTA (differential thermal analysis) for confirming crystallization characteristics of materials is used. Subsequently, the outline of the formation of the glass optical fiber according to the present embodiment will be described. A glass material for a core and a glass material for a clad having different refractive indexes are obtained in advance through the above manufacturing steps. The refractive index of the glass material for the core is higher.

These glass materials are machined to form cylindrical parts having different diameters as the core part and the clad part, and holes for accommodating the core part are bored in the clad part, and the rod-in-tube method is used. Get the preform. After that, the preform is heated from the outer peripheral side by a heater, held at a temperature equal to or higher than the glass transition temperature to be softened, and the end portion is drawn into a fiber shape to obtain an optical fiber. Since each of the glass materials is difficult to crystallize even when it is held at the softening temperature overlapping the temperature range where it can be crystallized, which is equal to or higher than the glass transition temperature, for a predetermined time, it is possible to easily perform fiber processing.

In an optical fiber having such a clad part and a core part, at least the clad part on the outer periphery is made of the glass according to the present embodiment which is hardly crystallized, and has a function as an optical fiber which is almost equal to the core part. If a glass material having a physical property value defined by a desired design required for is arranged, for example, a general phosphate-rich glass that can be crystallized is used as the core part, the crystallization heat value of the crystallization is generated in the core part. It is possible to manufacture a reliable optical fiber without using a small material. On the other hand, it is naturally possible to use glass that is hard to crystallize the core portion, and the degree of difficulty in crystallizing the core portion can be appropriately set according to the manufacturing process of the optical fiber to further relax the processing conditions for fiberization. You can also

As described above, in the glass according to the present embodiment, the phosphate-rich glass is made to contain an oxide of any one or more elements of Groups 3B to 5B of the Periodic Table, and the crystallization heat in this glass is increased. Since the amount is set to 60 J / g or less and the thermal stability as a glass is improved, crystallization as a material is less likely to occur, and the temperature is maintained near the crystallization temperature by processing accompanied by reheating to a glass transition temperature or higher. Even if it is, you can secure a longer time to completely crystallize,
Processing conditions such as optical fiber can be greatly relaxed, while the characteristics of phosphate glass can be fully exhibited, processing to optical fiber etc. can be reliably performed, and stress relaxation processing time for glass can be shortened. The production conditions can be greatly eased. In addition, if the raw material is adjusted to increase the molar ratio of the network modifying component while containing a small amount of fluorine, the behavior of the raw material melt during production will be stabilized by fluorine and can be transferred to the glass state without any trouble. In addition to a clean glass state without deterioration, the proportion of the network modifying component is increased to obtain a glass material that has physical properties compatible with other glasses having properties such as low photoelasticity. Adjustment is also easier.

In the glass according to the above-mentioned embodiment, the optical fiber is formed as each material for the core and the clad, but it is not limited to this, but it has the property of being chemically crystallized, It can be used for various purposes as a glass with a high content of phosphate, which has a wide working range (temperature, holding time) that does not crystallize during its production or processing heat treatment. Further, in the glass according to the above embodiment,
Two materials having different refractive indexes are used to form the core and the clad of the optical fiber, respectively, but the present invention is not limited to this, and it is also possible to use only one of the core and the clad. it can. Further, in order to form a special optical fiber made of the same material as a whole or a general glass fiber, it may be configured to be used as a single and uniform structure for the whole fiber.

[0031]

EXAMPLES The evaluation results of the ease of manufacturing an optical fiber using the glass according to the present invention and the evaluation results comparing various characteristics when the content of the additive is changed will be described. In this example, barium metaphosphate (Ba (Ba (M)) was used as the starting material of the basic composition so that barium oxide (BaO) was produced as the network-modifying component of glass and diphosphorus pentoxide (P ₂ O ₅ ) was produced as the network-forming component. Glass production is carried out using PO ₃ ) ₂ ). The molar ratio of BaO and P ₂ O ₅ is 1.0 when the starting material is glass as it is. Also,
Barium carbonate (BaCO ₃ ) or barium fluoride (BaF ₂ ) is mixed as an additive to adjust the proportion of barium oxide (BaO) produced as a network modification component. Further, boron oxide (B ₂ O ₃ ) or germanium oxide (GeO ₂ ) is used as an additive that suppresses crystallization of glass.

(Example 1) First, a plurality of glasses having a high phosphate content according to the present invention were produced with different crystallization calorific values, and comparative evaluations were made regarding the success or failure of fiber drawing.
As Examples A, B, C and D, glasses having crystallization heat values [J / g] of 142, 98, 51 and 32 were produced. Each of the examples contains 41.5, 42.7, 41.4, and 42.0 mol% of phosphorus pentoxide with respect to the entire glass, respectively. The phosphate content ratio of the glass and the heat value of crystallization in each of the above examples are collectively shown in the upper side of Table 1.

[0033]

[Table 1]

The evaluation results comparing the glass of each of these examples with respect to the success or failure of fiber formation will be described. A 40 mmφ rod was molded as a sample from the glass of each example, the rod was suspended in a vertically arranged tubular furnace, and heating was continued at a heating rate of 1 ° C./min until the rod spontaneously dropped or deformed. For each example, the evaluation contents such as whether or not the rod dropout portion is deformed and whether or not fiber drawing is possible are shown in the lower side of Table 1.

In Examples A and B in which the heat value for crystallization exceeded 60 J / g, the rod pull-down portion was deformed due to crystallization and could not be continuously formed into a fiber, but the heat value was 60 J / g or less. In Examples C and D, the fiber can be formed, and no deformation of the rod withdrawal part was observed. In addition, as a result of observation with an optical microscope, no precipitation of crystals was observed in Examples C and D.

From this, it was confirmed that the glass having a crystallization heat value of 60 J / g or less according to the present invention does not crystallize even when processed in a temperature range exceeding the glass transition temperature, and can be reliably made into a fiber. (Example 2) A plurality of glasses according to the present invention are manufactured by changing the content ratio (mol%) of boron oxide or germanium oxide, and the calorific value of crystallization, photoelastic constant, refractive index, etc. are compared. As a first example, barium oxide is contained in an amount of 48.6 mol%, diphosphorus pentoxide is contained in an amount of 46.1 mol%, and boron oxide is contained in an amount of 0.4 mol%. A glass having a molar ratio with phosphorus of 1.054 was produced.

Next, as a second embodiment, barium oxide is contained in an amount of 48.8 mol%, diphosphorus pentoxide is contained in an amount of 45.7 mol%, and boron oxide is contained in an amount of 0.7 mol%. A glass having a molar ratio with diphosphorus of 1.068 was produced. As a third embodiment, barium oxide is 48.1 mol%, diphosphorus pentoxide is 44.9 mol%, and boron oxide is 1.3 mol%, respectively. A glass having a molar ratio of 1.071 was produced.

Further, as a fourth embodiment, barium oxide (51.7 mol%), diphosphorus pentoxide (39.6 mol%), and germanium oxide (0.7 mol%) are included in the whole glass, respectively. A glass having a molar ratio of barium to phosphorus pentoxide of 1.306 was produced. In addition, as a fifth example, barium oxide is contained in an amount of 51.4 mol%, diphosphorus pentoxide is included in an amount of 39.7 mol%, and germanium oxide is included in an amount of 1.1 mol%, respectively. A glass having a molar ratio of 1.295 was produced.

As a sixth embodiment, barium oxide is 51.1 mol%, diphosphorus pentoxide is 39.3 mol%, and germanium oxide is 1.5 mol%, respectively. A glass having a molar ratio with phosphorus of 1.300 was produced. Regarding the molar ratio of barium oxide and diphosphorus pentoxide, when boron oxide is contained, barium metaphosphate as a starting material is adjusted by mixing an appropriate amount of barium carbonate as an additive, and when germanium oxide is contained, Then, barium metaphosphate as a starting material is mixed with an appropriate amount of barium fluoride as an additive for preparation. The compositional contents of the glass in each of the above examples are collectively shown on the upper side of Table 2.

[0040]

[Table 2]

In the production of the glass of each Example, after melting barium metaphosphate as a starting material and barium carbonate (or barium fluoride) as an additive, particularly in the case of adding barium fluoride, the raw material melt contains Fluorine generated from the added barium fluoride is present. When moist air is blown into the raw material melt and the water in the air is reacted with the fluorine in the raw material melt, the fluorine becomes hydrogen fluoride. By volatilization of the hydrogen fluoride from the raw material melt, only fluorine is reduced from the raw material melt. Then, when chlorine gas is blown into the raw material melt to react chlorine with water in the raw material melt, hydrogen forming water becomes hydrogen chloride. This hydrogen chloride volatilizes in a gas state from the raw material melt, and the water content also decreases from the raw material melt. After that, the raw material melt is stirred to be homogenized, and then gradually cooled in a mold to obtain glass.

With respect to the glass manufactured as described above, the actual values of the crystallization heat value, the refractive index, and the photoelastic constant were measured. The measured values are shown on the lower side of Table 2. This measurement is based on JIS K
7122 “Plastic transition heat measurement method”. However, since the object to be tested is not plastic, the test piece used is one that is roughly crushed into particles (about 0.5 mm to 2 mm).

Although the crystallization heat value is measured and evaluated by DSC, it is not limited to this and can be measured by another method such as TG-DTA. However, since the numerical values may vary depending on the measurement conditions and the measurement method of the calorific value, it is desirable to unify and compare the evaluation criteria (especially if a standard evaluation method is established, match it). The refractive index is for visible light having a wavelength of 589.3 nm. Further, the photoelastic constant is obtained by measuring the optical path difference generated in the center of the glass when a compressive load is applied to the glass having a diameter of 10 mm and a length of 10 mm in a predetermined direction using He-Ne laser light.

As shown in Table 2, the photoelastic constant was 0.6 [× 10] in each example in which boron oxide was added.
^-12 (1 / Pa)] or less, and 0.3 [× 10 ^-12 (1 / Pa) in each case of adding germanium oxide in which the molar ratio of barium oxide and diphosphorus pentoxide is 1.25 or more. The values below are obtained respectively. In addition, the refractive index is around 1.6 in all the examples, which is sufficiently lower than that of lead glass having the same photoelastic constant. Here, comparing the respective examples with respect to the increase / decrease in the amount of heat generation with respect to the change in the content ratio of boron oxide or germanium oxide, it can be seen that the amount of boron oxide and germanium oxide increases and the amount of heat generated by crystallization decreases. Then, in any of the examples, the heat value of crystallization was less than 60 J / g.

Subsequently, the glass having the composition of the fourth embodiment, that is, 51.7 mol% barium oxide, 39.6 mol% diphosphorus pentoxide, and 0.7% germanium oxide were used.
The core material, which is a glass contained in each mol%, and the glass having the composition of the third embodiment, that is, 48.1 mol% barium oxide and 44.9 mol% diphosphorus pentoxide,
An optical fiber was manufactured by using a clad material which is glass containing 1.3 mol% each of boron oxide.
The core material and the cladding material each have a refractive index of 1.5.
They are 99 (nD) and 1.595 (nD).

These glass materials are machined into cylindrical shapes with different diameters for the core and the clad, and holes for accommodating the core are formed in the clad, and preformed by the rod-in-tube method. (40 mm
φ) was obtained. After that, when the preform is heated and stretched at 650 ° C. which is higher than the glass transition temperature for a predetermined time, the preform is not crystallized, and the core diameter is 10 μm and the clad diameter is 12 μm.
A 5 μm transparent optical fiber could be continuously manufactured. According to each of the above examples, the glass of the present invention has a crystallization calorific value of 60 J / g or less by appropriately containing boron oxide or germanium oxide, so that the glass in the fibrous processing accompanied by reheating to the glass transition temperature or more. It has been confirmed that the crystallization of the can be suppressed and the optical fiber can be easily manufactured.

[0047]

As described above, according to the present invention, the heat of crystallization in the glass having a high phosphate content of 38 mol% or more of diphosphorus pentoxide is set to 60 J / g or less, and the thermal stability of the glass is improved. As a result, crystallization as a material is less likely to occur, and even when the temperature is kept near the crystallization temperature during processing accompanied by reheating to a glass transition temperature or higher, there is a time margin until complete crystallization. It can be secured for a longer time, processing conditions such as optical fiber can be greatly relaxed, and while making the best use of the features of phosphate glass, processing to optical fiber etc. can be reliably performed and the stress relaxation processing time for glass can be shortened. As a result, the production conditions of the glass itself can be greatly relaxed. In addition, during processing, even if there is a portion that reaches a temperature range that can induce crystallization,
In particular, by being able to reduce the influence of surface crystallization, it is possible to suppress the deformation of the material and the like due to the generation of crystals, and it is possible to significantly reduce the adverse effects during processing.

Further, according to the present invention, diphosphorus pentoxide is added to 3
Crystallization occurs when the composition is 8 mol% or more and further contains a network modifying component and further contains an oxide of any one or more elements of Groups 3B to 5B of the periodic table. In addition to being difficult, it has the effect that it can be a material that has, or is very close to, the features and characteristics of high phosphate content glass.

Further, according to the present invention, as an additive material for increasing the ratio of the network modifying component in the vitrified state, an element having a high electron polarizability of ions contained in the network modifying component or a substance containing fluorine is added to prepare a raw material. While keeping a small amount of fluorine in the melt, by increasing the molar ratio of the network modification component, the behavior of the raw material melt at the time of production can be crystallized by being stabilized by fluorine and being transferred to the glass state. Is suppressed, resulting in a clean glass state without quality deterioration, and it is possible to obtain a glass in which the molar ratio of the network modifying component is increased without any trouble.

Further, according to the present invention, by melting a starting raw material and then blowing a predetermined gas which reacts with fluorine to volatilize the fluorine as a fluoride gas to reduce the amount of fluorine in the raw material melt, the glass can be reduced. This has the effect of suppressing the adverse effects of the presence of fluorine in the state and producing a clean glass with improved homogeneity. Further, according to the present invention, the amount of the network modifying component is increased by adding a trace amount of fluorine to increase the molar ratio to 1.25 or more, while stabilizing the behavior of the raw material melt during production with fluorine. By shifting to the glass state, even if there are many network modifying components, the raw material melt can be shifted to the glass state without hindrance, and crystallization hardly occurs, and by adjusting the proportion of the network modifying components appropriately, phosphorus It has an effect that the excellent characteristics of the salt glass can be more stably drawn out.

Further, according to the present invention, barium oxide having a property of reducing a photoelastic constant is contained as a network modifying component, and boron oxide and / or germanium oxide is contained as an additive for reducing a heat value of crystallization. By adjusting the proportion of barium oxide and adjusting the content of the phosphate as the main component to be a predetermined photoelastic constant, other glass materials having characteristics of particularly low photoelasticity are obtained. , Materials with good matching in properties such as refractive index, coefficient of thermal expansion, softening temperature, and hard to crystallize. For example, suitable processing integrally with other glass materials as the core or clad of optical fiber. It has the effect that Furthermore, boron oxide and germanium oxide have the effect of being able to adjust the photoelastic constant, refractive index, and thermal characteristics in addition to suppressing crystallization, and the characteristics according to the purpose can be set appropriately by adjusting the addition amount.

Further, according to the present invention, silicon dioxide and / or alumina, which influences various properties of glass, is added as an additive, and its behavior and physical properties are maintained until the transition from the raw material melt state to the glass state during production. Liquid phase temperature, chemical stability, photoelastic constant,
There is an effect that performance can be improved by adjusting various characteristics such as refractive index, transmittance, and durability.

Further, according to the present invention, at least a part is formed of a high phosphate content glass having a crystallization calorific value of 60 J / g or less, and the thermal stability of the phosphate glass as a fiber material. As a result, it is possible to secure a longer time margin until complete crystallization even when the material outer periphery is kept near the crystallization temperature in the fiber-like processing that involves reheating to above the glass transition temperature. The processing conditions can be greatly relaxed, and the advantages of phosphate glass can be exerted, while the fiber-shaped processing can be performed reliably and the manufacturing is easy. Further, each fiber portion can have an appropriate configuration that satisfies the physical property condition that it can function as an optical fiber, and has an effect that it can surely function as an optical fiber of phosphate-rich glass.

Further, according to the present invention, of the optical fibers having the core portion and the clad portion, the clad portion is formed of a high phosphate content glass having a crystallization calorific value of 60 J / g or less. Since it occupies a large volume and is located on the outer peripheral side that is exposed to high heat, the thermal stability is improved in the clad part that is most susceptible to crystallization during optical fiber manufacturing, and reheating above the glass transition temperature is possible. Even if the clad part is kept near the crystallization temperature in the accompanying fibrous processing, it is possible to secure a longer time margin until complete crystallization, and it is possible to greatly relax the processing conditions, ensuring fibrous processing. It has the effect that it can be manufactured easily.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C03C 13/04 C03C 13/04 G02B 6/00 376 G02B 6/00 376A (72) Inventor Kenji Morinaga Fukuoka Prefecture 1232-35 F term, Nakagawa-machi, Nakagawa-machi, Chikushi-gun (reference) 2H050 AB08 4G062 AA01 AA06 BB09 CC10 DA02 DA03 DB02 DB03 DC01 DC02 DC03 DD05 DD06 DE01 DE02 DF01 EA01 EA02 FB01 FA02 FA01 EF01 EF01 EF01 FA02 FA02 EF01 EF01 EF01 EF01 FA02 FA02 FA02 FA02 FA01 FA02 FA02 FA01 FA02 FA02 FA01 FA02 FA02 FA02 FA02 FA02 FC01 FC02 FD01 FD02 FE01 FE02 FF01 FG01 FH01 FH02 FJ01 FK01 FK02 FL01 GA01 GA10 GB01 GC01 GD01 GD02 GE01 GE02 HH01 HH02 HH03 HH05 HH07 07 HKK08 KK KK KK JJ01 KK

Claims (9)

[Claims] 1. A glass comprising at least 38 mol% of diphosphorus pentoxide as a network-forming component and having a crystallization heat value of 60 J / g or less. 2. The glass according to claim 1, wherein the glass contains 0.1 mol% or more of an oxide of any one or more elements of Groups 3B to 5B of the periodic table and has at least a high electronic polarizability of ions. A glass comprising a network-modifying component containing an element, wherein the molar ratio of the network-modifying component to the network-forming component is 1.0 or more. 3. The glass according to claim 1 or 2, wherein the starting material is one or a plurality of substances containing the respective elements constituting the network modifying component and the network forming component, respectively. On the other hand, a fluoride of an element having a high electron polarizability of the ion contained in the network modifying component as an additive material for increasing the network modifying component, a fluoride and an oxide of an element having a high electron polarizability of the ion, or a predetermined amount A glass comprising a predetermined amount of a fluoride and an oxide of an element having high electron polarizability of ions. 4. The glass according to claim 3, wherein a predetermined gas that reacts with fluorine is blown into the raw material melt obtained by heating and melting the starting material, and the fluorine in the raw material melt is used as the predetermined gas. A glass characterized by being reacted and volatilized from a raw material melt in the state of a fluoride gas, and then brought into a vitrified state. 5. The glass according to claim 3 or 4, wherein a molar ratio of the network modifying component and the network forming component is 1.25.
A glass characterized by the above. 6. The glass according to any one of claims 2 to 5, wherein the network modifying component is barium oxide, and the oxide of a group 3B to 5B element of the periodic table is boron oxide and / or oxide. A glass characterized by being germanium. 7. The glass according to claim 1, which contains a predetermined amount of silicon dioxide and / or alumina. 8. An optical fiber comprising at least a part of the glass according to any one of claims 1 to 7. 9. The optical fiber according to claim 8, wherein at least a clad portion is formed of the glass.