JPS6022659B2 - Acid-leaching glass for producing flexible optical fiber bundles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the composition of acid-leaching glass when a flexible optical fiber is made using acid-leaching glass.

When optical fibers are used as images and guides, their ends must be arranged in one-to-one correspondence.

Particularly when the image and guide optical fiber bundle is used as an endoscope, the optical fibers are required to be fixed to each other at both ends, and the intermediate portion thereof is required to be movable. . By the way, various methods have been proposed for manufacturing optical fibers having such fixed end portions and flexible intermediate portions. For example, a core glass with a relatively high refractive index is placed in the inner ring of a double ring vortex, and a covering glass with a relatively low refractive index is placed in the outer ring.
Heat the double layer to an appropriate temperature, pull both glasses through the bottom hole of the tube, cover the core glass with the covering glass, and wind the obtained optical fiber in a loop shape without gaps. Fix the end of the loop with adhesive, wrap it in a line in a loop shape without any gaps in the same way as before, fix it with adhesive at the fixed part of the loop formed before, and repeat this operation to make the desired shape. A method consisting of obtaining a thick loop-shaped optical fiber, cutting approximately the center of the fixed portion of the loop-shaped optical fiber at right angles to the length of the optical fiber, and polishing these two cut surfaces. A method for manufacturing optical fibers for guides and image guides that have maneuverability is known.

In this method, optical fibers of the desired thickness can be made in one heating step (for example, 20 fibers), so the subsequent manufacturing process, that is, the arranging of the optical fibers, is very labor intensive as the optical fibers are extremely thin. Since it requires skill and the risk of cutting is high, the yield rate of image and guide using this method is poor.
This also has the disadvantage of high cost.
As another method, a method for manufacturing optical fiber bundles by acid porting is known. That is, in this method, a core glass with a relatively high refractive index is placed in the innermost vortex of the triple equilibrium, a covering glass with a relatively low refractive index and good acid resistance is placed in the outer vortex, and a covering glass with a relatively low refractive index and good acid resistance is placed in the outermost vortex. Place the acid-melting glasses in each clay swirl and
Heat the entire Jukandan to an appropriate temperature, draw the above-mentioned glasses through the bottom hole of the Jukandan, cover the core glass with the covering glass, and
Furthermore, by coating the outer periphery with acid-eluting glass, an optical fiber (the diameter of this optical fiber is about 200 threads) was obtained.
A large number of them (for example, 10,000) are bundled (in this case, if necessary, the bundled optical fibers are placed in an acid-eluting glass tube), fused, heated to an appropriate temperature, and the diameter of the optical fibers is Both ends of the hard optical fiber thus obtained are coated with an acid-resistant coating, and the entire optical fiber is then brought into contact with an acid (for example, nitric acid) to form an optical fiber. It consists of eluting acidic glass from the middle part of the east. Compared to the above-mentioned method, this method allows optical fibers to be arranged with a thickness of approximately 200 mm, making it easier to arrange the optical fibers, and there is very little risk of breakage. Moreover, after the arrangement, the above-mentioned fear is completely eliminated because they are integrated by heat fusion. Therefore,
According to this method, the production yield is higher and the cost can be significantly reduced compared to the above-mentioned method. However, in this method, the acid-eluting glass exists in a very narrow gap, so when it is eluted with acid, the acid-resistant coating layer of the optical fiber is inevitably eroded, causing unevenness on the surface of the optical fiber. This poses a practical problem in that it causes breakage of the product and shortens the life of the product.

A method to prevent this is to sufficiently increase the acid elution property of the acid-leaching glass, but this is discussed in Japanese Patent Publication Shobushi General 623 (or U.S. Pat. No. 3,624,816).
In, &08: about 45% by weight, Mari○: about 45% by weight
, La203: about 8% by weight (converted to mol% B20
3: 65.7 mol%, Ba○: 29.8 mol% to 20
3:2.5 mol%) is disclosed. In the case of this acid-eluting glass, the acid-eluting property is sufficiently high, but the water resistance is very poor, and there is a risk that the acid-eluting glass may come out during polishing of the east end of the optical fiber, making polishing difficult. be. In addition, glass with a high content of matrix ○, such as the above-mentioned acid-leaved glass, has a large change in viscosity due to changes in temperature, resulting in so-called short-legged glass, so it is difficult to imagine optical fibers for guides, such as the optical fiber Higashi. It becomes extremely difficult to produce fibers with extremely high dimensional accuracy. The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to provide a low cost and highly durable product.
The present invention provides acid-leaching glass necessary for manufacturing flexible optical fibers.

That is, the present invention relates to an acid-leaching glass having the following composition and intended for use as a portable optical fiber. 9.0 mol%<Si.

2<15.0 mol% Spots. 0 mol% < Horse 03 < 57.0 mol% 10.0 mol% Arm 0ku 27.0 mol% 5.0 mol% < (total of one or more of Na20, K20, Li20) <19 .0 mol% Si02 is 9.
If it is less than 0 mol%, sufficient water resistance cannot be obtained.15
．． If it is 0 mol % or more, it is difficult to obtain sufficient acid dissolution.

When &03 is 38.0 mol % or less, it is difficult to obtain sufficient acid elubility. If it is 57.0 mol% or more, sufficient water resistance cannot be obtained.

If the spot ○ is less than 10.0 mol%, the viscosity when heating and stretching the optical fiber East becomes too thick, 27.0 mol%.
In the above case, the change in viscosity due to change in temperature becomes too large. If the total of one or more of Na20, K20, and Li20 is less than 5 mol%, the expansion coefficient becomes too high, 4. This makes it difficult to produce an acid-leaching glass with a coefficient of thermal expansion similar to that of the core glass and the covering glass. Further, if the content is 19.0 mol% or more, sufficient water resistance cannot be obtained. In addition, if necessary, 8 mol% or less of A203, 12
Zn○ below mol%, Mg○ below 5 mol%, Ca0,
S or a small amount of coloring agent may be attached.

Also, a small amount of As2Q, SQ03, etc. is added as a clarifying agent. Examples of the present invention are shown in Tables 1 and 2.

The transition point in the table is the temperature when the viscosity is 1 to 3 [g arc-lsec-1], and the bending point is the temperature when the viscosity is 1 to 1 to 1 and 2 [g arc-lsec-1].
For temperature water resistance and acid resistance (powder method) in sec-1], a sample is ground to a particle size of 420 to 590'', washed with methyl alcohol, and then dried.

Then, the specific gravity gram of this powder sample is placed in a platinum dragon for elution. Next, this was placed in a quartz glass round bottom flask containing the test solution, treated in a boiling water bath for 60 minutes, and then dried.
This value is the weight loss (%) of the sample after drying. For water resistance, use distilled water (pH: 6.5-7.
5), and in the case of acid resistance, use 1/100 as the test solution.
Test using N nitric acid (pH: approx. 2.2). Table 1 W: Weight ratio M: Mol% Table 2 W: Weight ratio M: Mol ratio

Claims (1)

[Claims] 1. An optical fiber is produced by coating the outer periphery of a core glass made of high refractive index glass with glass having a low refractive index and acid resistance, and further coating the outer periphery with acid-eluting glass. A flexible optical fiber in which a large number of optical fibers are bundled, heated, and stretched to form a hard optical fiber bundle, and then acid-eluting glass is eluted from the middle part of the optical fiber bundle except for both ends with acid. A flexible acid-leaching glass for producing an optical fiber bundle, characterized in that the acid-leaching glass used in producing the fiber bundle is an acid-leaching glass having the following composition. 9.0 mol%<SiO_2<15.0 mol%38.0 mol%<B_2O_3<57.0 mol%10.0 mol%<
BaO<27.0 mol%5.0 mol%<(Na_2O,
sum of one or more of K_2O, Li_2O) <19
．． 0 mol% 0 mol%≦ZnO<12.0 mol% 0 mol%≦MgO<5.0 mol% 0 mol%≦CaO<5.0 mol% 0 mol%≦SrO<5.0 mol% 0 mol% ≦Al_2O_3<8.0 mol%2 An optical fiber is produced by coating the outer periphery of a core glass made of high refractive index glass with glass having a low refractive index and acid resistance, and further coating the outer periphery with acid-eluting glass. , a large number of them are bundled and placed in a tube made of acid-eluting glass, the tube is heated and stretched, and then the acid-eluting glass is eluted with acid from the middle part excluding both ends, so that it has flexibility. For manufacturing a flexible optical fiber bundle according to claim 1, wherein the glass material of the tube used in manufacturing the optical fiber bundle is an acid-leaching glass having the following composition: Acid leaching glass. 9.0 mol%<SiO_2<15.0 mol%38.0 mol%<B_2O_3<57.0 mol%10.0 mol%<
BaO<27.0 mol%5.0 mol%<(Na_2O,
sum of one or more of K_2O, Li_2O) <19
．． 0 mol% 0 mol%≦ZnO<12.0 mol% 0 mol%≦MgO<5.0 mol% 0 mol%≦CaO<5.0 mol% 0 mol%≦SrO<5.0 mol% 0 mol% ≦Al_2O_3<8.0 mol%