JP2625444B2 - Optical fiber unit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical fiber unit using a low-loss optical fiber as a transmission medium.

[Prior Art] In optical fiber communication, an optical signal is transmitted using an optical fiber as a transmission line. The low-loss optical fiber used for such optical fiber communication is made by coating a thin quartz glass with nylon or the like, and has a small mechanical strength. In particular, undersea cables laid on the deep sea floor are subjected to pressures of several hundred atmospheres or more, and if they are used as they are, uneven force is applied in the radial direction due to uneven coating of the fiber strands, resulting in transmission loss. Increase.

Further, when the cable is broken, seawater enters into the inside from the fractured surface and reaches the optical fiber, which lowers the strength and may cause a fracture. For this reason, in general, an optical fiber is a highly reliable optical fiber submarine cable by being housed and protected in a pressure-resistant structure.

A typical tension member disposed in such a pressure-resistant structure of a cable is made of oxide glass, copper, or the like.

[Problems to be Solved by the Invention] However, in the case of a conventional tension member using an ordinary oxide glass fiber, although it has strength, its elastic modulus is low, and the mechanical performance as an optical fiber support is insufficient. It is. On the other hand, in the case of a steel wire, both the strength and elastic modulus are sufficient, but the specific gravity is large and the specific strength and the specific elastic modulus are both inferior to those of glass fiber. Further, an aromatic polyamide fiber reinforced FRP represented by Kevlar has also been proposed, but it is difficult to commercialize it due to its price.

An object of the present invention is to provide an optical fiber unit that is lightweight and has a high elastic modulus at a low cost.

[Means for Solving the Problems] The present invention mainly has an oxynitride glass fiber bundle having an elastic modulus of 12500 kg / mm ² or more and a tension member formed from a resin impregnated in the fiber bundle, Provided is an optical fiber unit in which a large number of optical fibers are arranged concentrically.

The oxynitride glass, which is a glass fiber raw material used in the present invention, has a structure in which oxygen atoms of oxide glass are replaced with nitrogen, and since the bond valence of nitrogen atoms is 3, conventional glass is used. In comparison, it has a higher elastic modulus. The method for producing the oxynitride glass, the melting method for melting a sol-gel method to dehydration condensation after hydrolysis of the metal alkoxide, or a metal oxide and a metal nitride, more N ₂ gas blowing method, porous glass NH
_{There are three} gas treatment methods and the like, and it is possible to obtain an elastic modulus of 12500 kg / mm ² or more, which cannot be achieved with conventional glass fibers.

The oxynitride glass fiber used as the reinforcing fiber in the present invention is Si13 to 24 at%, Ca10 to 21 at%, Mg0 to
5.2at%, Al0-15.1at%, N7.5-25at%, M0-5at%
(M: Zr, Sr, Ba, Y, Ce, Na, B, La, K, Ti).

If the content of Si is less than the above range, crystallization occurs and a glassy state cannot be obtained. On the other hand, if it is more than this range, the elastic modulus decreases to 12,500 kg / mm ² or less.

If the content of Ca is less than the above range, crystallization occurs, while if it exceeds this range, the elastic modulus is 12500 kg / mm ²
And decline.

Further, when the Mg content exceeds the above range, crystals are formed.

On the other hand, if the nitrogen content is less than the above range, the effect of the nitrogen content is not obtained, and if it exceeds this range, crystallization occurs.

Oxynitride glass used in the present invention is strength, preferably produced by a melt process in terms of N ₂ content. To obtain oxynitride glass by the melting method,
The metal nitride is added to the metal oxide and melted at a high temperature.

Examples of metal oxides include SiO ₂ , CaO, MgO, Al ₂ O ₃ , S
rO, Na ₂ O, K ₂ O, La ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , TiO ₂ , Na ₂ O, K
₂ O, BaO, B ₂ O _{3 and the} like.

Examples of the metal nitride include Si ₃ N ₄ and AlN.

In order to melt these metal oxides and metal nitrides, a heating furnace such as an electric furnace or an image furnace is used, under a nitrogen atmosphere, at a temperature of 1400 to 1900 ° C and a heating rate of 10 to 800 ° C / min. Process.

The obtained glass is heated and melted at a temperature of 1100 to 1600 ° C. under a nitrogen atmosphere, and spun at a spinning speed of 20 to 3000 m / min to obtain a continuous fiber.

The glass fiber thus obtained has a modulus of elasticity of 12500-1.
8000 kg / mm ^2, with a tensile strength 70~500Kg / mm ^2.

The glass fiber preferably has a fiber diameter of 3 to 150 μm. If the fiber diameter is smaller than this, spinning is difficult,
On the other hand, if it exceeds this, the strength is extremely reduced, which is not preferable.

50 to 2000 of such glass filaments are bonded by a matrix resin to form a tension member.

Examples of the matrix resin of the tension member include unsaturated polyester resin, epoxy resin, polyimide resin, polyphenylene sulfide (PPS), polyether sulfone (PES), polyether ether ketone (PEEK), and the like. You may mix and use more than one kind. The ratio of the glass fiber in the tension member is about 40 to 65% by weight.

In order to manufacture a tension member using oxynitride glass fibers, any of the conventionally known methods for producing a fibrous FRP can be adopted, and a typical example is a pultrusion method.

EXAMPLES Next, the present invention will be described more specifically based on examples. FIG. 1 is a sectional view of the optical fiber unit of the present invention. In FIG. 1, a fiber unit 1 has a tension member 2 of an oxynitride glass fiber bundle at the center, and a large number of optical fiber wires 3 are arranged concentrically at a distance from the tension member. An elastomer 4 is filled between the tension member and the fiber strand and between the fiber strands, and a nylon layer 5 is coated around the elastomer 4. The tension member 2 is manufactured by the following manufacturing example.

Production Example 1 SiO ₂ 20.0 mol%, CaO 40.8 mol%, MgO 12.0 mol%, Al ₂ O ₃
14.4 mol% were mixed and melted in air at 1500 ° C. for 2 hours.
After cooling the mixture, pulverize to about 10 μm using a ball mill, add 12.8 mol% of Si ₃ N ₄ , and use a boron nitride crucible,
Melting was performed at 1750 ° C. for 30 minutes in nitrogen to obtain oxynitride glass. The obtained glass is placed in a boron nitride crucible placed in a spinning device, and heated and spun at 1380 ° C. under a nitrogen atmosphere at 1380 ° C. using a cylindrical carbon heating element whose periphery is kept warm with a heat insulating material. Was. Spinning speed 1500m / min
, A continuous fiber having a diameter of about 15 μm was obtained. The tensile elastic modulus of the obtained glass fiber was 12,600 kg / mm ² .

A tension member was manufactured by a pultrusion method using the obtained oxynitride glass long fibers and an epoxy resin as a matrix.

[Effects of the Invention] According to the present invention, an optical fiber unit that is lightweight and has a high elastic modulus can be obtained at low cost.

[Brief description of the drawings]

 FIG. 1 is a sectional view of an optical fiber unit. The main symbols in the figure are as follows. 2: tension member, 3: optical fiber.

Claims (1)

(57) [Claims] An optical fiber element comprising: an oxynitride glass fiber bundle having an elastic modulus of not less than 12,500 kg / mm ² and a tension member formed of a resin impregnated in the fiber bundle. An optical fiber unit in which wires are arranged.