JPH0576006B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention involves gathering a plurality of optical fibers around a central tensile strength member, and filling a buffer layer (UV resin) between the optical fibers. This invention relates to a submarine optical cable in which a metal pressure layer, a tensile strength member, a metal tube, and an insulator are sequentially laminated on an optical fiber unit.

[Background Art and Problems] Submarine optical cables laid on the seabed and used as long-distance communication lines are required to have sufficient resistance to high water pressure.

FIG. 1 shows a cross-sectional structure of an example of such a submarine optical cable, in which 1 is an optical fiber unit in which a plurality of optical fiber cores are assembled around a central tensile strength member and filled with a cushioning material, and 2 is a metal pressure-resistant layer. , 3 is a tensile strength wire made of piano wire or the like, 4 is a metal tube, 5 is
is an insulating layer made of plastic or the like.

The outer periphery of the insulating layer 5 may be further coated if necessary.

In such a submarine optical cable, a gap E exists between the optical fiber unit 1 and the metal pressure layer 2, between the metal pressure layer 2 and the tensile strength wire 3, and between the tensile strength wire 3 and the metal tube 4. When the cable encounters a problem, it becomes a passageway for seawater to enter, and is a factor that causes damage to spread due to the so-called water running phenomenon.

Therefore, such a gap E is usually filled with a compound during cable manufacture to suppress the degree of water running.

FIG. 2 is a schematic diagram showing an example of submarine optical cable manufacturing equipment, in which 10 is an optical fiber unit supply, 11a, 11b, and 11c are 3 parts of the metal voltage-resistant layer 2.
Divided piece supply supplying divided pieces, 12
is a tensile strength wire assembling machine for assembling tensile strength wires 3, and the optical fiber unit 1 and the materials 2a, 2b, 2c of the divided individual pieces are passed through the hollow shaft 12a of the tensile strength wire assembling machine, and then the divided individual pieces are assembled and compound filled. It is supplied to an apparatus 13, where the metal pressure-resistant layer 2 is formed while being filled with a compound. The tensile strength wires 3 drawn out from the tensile strength wire drum 12b are collected in the collecting die 14, and the compound is also filled in this collecting step. 15 is a metal tape supply for forming a metal tube; 16 is a metal tube forming device that forms metal tapes vertically into a pipe shape and welds the joints using a welding machine 16a; 17 is a metal tube forming device; It is a drum that winds up things that have gone up to that point.

In such a manufacturing apparatus, the compound for preventing water runout is stored in compound storage tanks 18a, 18b, 19 in the divided piece assembly and compound filling device 13 and the assembly die 14.
A, 19b are supplied by a pump 20 or the like, but if an epoxy resin or silicone resin is used as this compound, the following drawbacks will occur.

(1) Since epoxy resin is hard after curing, the bending characteristics of the cable deteriorate. Furthermore, when the cable is bent by winding it in a drum or the like, cracks are likely to occur in the filled resin. Furthermore, since the shrinkage during curing is large, an unnecessarily compressive force is applied to the optical fiber, causing an increase in transmission loss.

(2) Condensation reaction types of silicone resins include dealcoholization, dehydrogenation, and dehydroxylaluminization (R ₂ NOH), but all of them are undesirable because they cause metal corrosion. In addition, the two-component addition reaction type has (a) poor adhesion to metals because the silicon itself has no tackiness, and when filled into a submarine optical cable, the optical fiber unit 1 can withstand metal pressure against the expansion and contraction of the cable. This causes a phenomenon of slipping within the layer. (b) The UV resin (ultraviolet curing type resin) filled in the optical fiber unit 1 is
Platinum (Pt), a catalyst for liquid silicone resin
However, there is catalyst poison, which poisons the silicone resin and prevents it from curing. (c) This type of silicon hardens while containing a large amount of unreacted Si-H bonds, so if it is placed under certain conditions (for example, by applying heat or adding moisture), it can be cured with other substances. Because they tend to generate a large amount of hydrogen (compared to nylon or urethane), this hydrogen vibrates within the sealed submarine optical cable and penetrates into the optical fiber unit, degrading the transmission characteristics of the optical fiber.

In addition to the problems that arise from the compound material as described above, there are also problems that are restricted by the manufacturing equipment for submarine optical cables.

In other words, submarine optical cables are usually longer than general electric wires and cables, spanning several tens of kilometers, but they are equipped with metal tubes 4 installed to block the transmission of moisture in the power supply line and seawater. Since welding must be performed continuously, it takes 50 to 100 hours of continuous operation to manufacture one length of submarine optical cable.

Therefore, the curing time of the filling compound must be at least 50 to 100 hours. If the curing time is short, there is a problem that the compound adhering to the inner wall of the die will harden during operation and cause clogging.

In addition, as shown in Figure 2, the compound to be filled is transported over long distances, so if it has a high viscosity, it will be difficult to transport.On the other hand, if the compound has a low viscosity, it may leak from the joints of the pressure-resistant pipes after being filled. There is also the problem that satisfactory filling is not achieved.

[Purpose of the invention]

In order to solve these various problems, this invention has developed a compound with excellent properties for maintaining high optical and mechanical properties of optical fibers and for manufacturing submarine optical cables. The purpose of the present invention is to provide a submarine optical cable that has excellent watertightness and does not deteriorate the transmission characteristics of the cable by filling the voids with .

[Summary of the invention]

In order to achieve the above object, this invention is a two-component mixture curing type polyurethane resin with excellent water resistance, which contains various types of polyol and isocyanate.
By appropriately adjusting the molecular weight, number of functional groups, NCO/OH equivalent ratio, filler, and type and amount of additives, the viscosity of each of the two liquids can be adjusted to 5000~
We formed a compound with a shear peel strength of 0.01Kg/mm ² to 0.05Kg/mm ² at 9000CPS, curing time 50 to 100 hours at room temperature, and filled the void in the submarine optical cable. Therefore, the above-mentioned problems are solved.

〔Example〕

Hereinafter, specific examples of composition materials of the compound that can achieve the object of the present invention will be shown.

Example 1 Liquid A Polytail HA manufactured by Mitsubishi Chemical Corporation (number average molecular weight approx.
2000 polyolefin polyol, hydroxyl group concentration
0.9meq/g) 3Kg, Polytail manufactured by Mitsubishi Chemical Corporation
HAB (polyolefin with number average molecular weight of approximately 2000)
1.3Kg and a high purity paraffinic oil containing virtually no aliphatic unsaturated double bonds (initial boiling temperature
324°C) were uniformly mixed to produce Solution A. The viscosity was 6100 CPS (28°C).

B Solution 4 kg of Polytail HA used in Solution A, 0.9 kg of high-purity paraffinic oil, and 0.6 kg of tolylene diisocyanate were mixed and reacted at 130° C. for 5 hours. After the reaction, add 3.1Kg of paraffin oil,
0.2 kg of diphenylmethane diisocyanate and 2.4 kg of Polytail HAB were added and mixed uniformly to obtain component B. The viscosity was 6200 CPS (28°C).

Physical properties of blended cured product The physical properties of the cured product after blending liquids A and B at a ratio of 1:1 and standing at room temperature for 10 days were as follows.

Shear peel strength with Al plate 1.4Kg/cm ² →0.014Kg/mm ² Initial compression modulus 6.5Kg/cm ² (Measured using a rheometer manufactured by Fudo Kogyo Co., Ltd. This is the compression modulus at a deformation amount of 4%.) Implementation Example 2 Liquid A Polytail HA manufactured by Mitsubishi Chemical Corporation (number average molecular weight approx.
2000 polyolefin polyol, hydroxyl group concentration
0.9meq/g) 3.6Kg, Polytail manufactured by Mitsubishi Chemical Corporation
HAB (polyolefin with number average molecular weight of approximately 2000)
0.5Kg and high purity paraffinic oil containing virtually no aliphatic unsaturated double bonds (initial boiling temperature
324°C) were uniformly mixed to produce Solution A. The viscosity was 6000 CPS (28°C).

B Solution 4 kg of Polytail HA used in Solution A, 1 kg of high-purity paraffinic oil, and 0.6 kg of tolylene diisocyanate were mixed and reacted at 130° C. for 5 hours.
After the reaction, add 3 kg of paraffin oil, 0.2 kg of diphenylmethane diisocyanate, and polytail.
0.8 kg of HAB was added and mixed uniformly to produce Solution B. The viscosity was 8000 CPS (28°C).

Physical properties of blended cured product The physical properties of the cured product after blending liquids A and B at a ratio of 1:1 and standing at room temperature for 10 days were as follows.

Shear peel strength with Al plate 2.9Kg/cm ² →0.029Kg/mm ² Initial compression modulus 14.3Kg/cm ² Here, the setting of curing time of 50 to 100 hours is based on a single length of submarine optical cable of at least 50Km. This is required from the manufacturing time, and the viscosity is 5000~
9000CPS has compound storage tanks 18a, 18b,
There is a value that can be transported by the pump 20 from 19a and 19b and that does not cause much leakage of the compound during the manufacturing process, which has been determined through calculations and experiments.

That is, the conditions that serve as the basis for this determination were set as follows.

Conditions: Resin sending path length L = 30 m Resin sending hose inner diameter D = 7 mm φ Resin sending flow rate 8 c.c./min Resin sending specific gravity ρ = 0.9, pump feeding pressure ΔP 4 to 5 Kg/cm ² Then, the resin viscosity η can be calculated from Hagen-Poiseuille's equation ΔP=8ηuρL/9.8a ² (1).

The average flow velocity is based on the above conditions: =Q/A A=(π/4)0.7 ² =0.83 =8/0.385×1/60 =0.346cm/sec =0.00346m/sec Therefore, from the above equation (1), ΔP=4Kg /cm ² _, ⁴ ×10 ⁴ = 8η ₁ × ^0.00346 , 5×10 ⁴ =8η ₂ ×0.00346×0.9 ×30／9.8×0.0035 ² η ₂ =8.032Kg/msec =8032CPS ...(3) After finding equations (2) and (3), calculate the viscosity of the resin. about
It was decided to be 5000 to 9000 CPS.

In addition, the shear peel strength with an Al plate is determined by bonding two aluminum plates with a width of 25 mm, a length of 100 mm, and a thickness of 1.5 mm with a compound in a range of 60 mm in length and 1 mm in thickness, as shown in Figure 3. It shows the strength when the bonded part peels off when both ends are pulled after being cured for 6 days at room temperature of 20°C.

Then, as shown in FIG.
It is applied to the inner surfaces of two aluminum pipes 22a and 22b with an inner diameter of 3 mm (approximately the shape of a pressure-resistant layer), and an outer diameter of
A 2.6 mm optical fiber unit 21 is held.

With such a test device, the aluminum pipes 22a, 2
When 2b is pulled in the direction of the arrow, a tensile force is applied to the optical fiber unit 21, but if the shear peel strength of the compound C to be tested is low, the optical fiber unit 21 slips within the aluminum pipe.

Therefore, the lower limit of shear peel strength was set as the test compound in which this slip phenomenon occurs.
0.010Kg/mm ² was obtained.

Furthermore, if the upper limit of shear peel strength is set to 0.05Kg/mm2 or ^more , the initial compression modulus of the resin will be approximately 10Kg/mm2.
cm ² or more, which is not desirable when considering the influence of lateral pressure characteristics on the fiber. In other words, a material with a Young's modulus of about 10 to 80 kg/ ^cm2 is used as the outer covering material for the fiber unit, and the initial compressive elastic modulus of the water running prevention compound to be filled is also smaller than that of the outer covering material.
This is because unless it is 10 kg/cm ² or less, it will not function as a cushion layer between the voltage-resistant layer and the fiber unit.

〔Effect of the invention〕

As detailed above, the viscosity of the two liquids is 5000~
A polyurethane compound with a curing time of 50 to 100 hours and 9000 CPS has the advantage that it does not cause any problems that would hinder manufacturing operations even when manufacturing long submarine optical cables.
Shear peel strength with Al plate after curing is 0.05 to 0.010
In the case of Kg/mm ² , it has an appropriate protective effect on the optical fiber unit, so if the cavity is filled with a compound having such characteristics, an extremely reliable submarine optical cable can be obtained.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing an example of a submarine optical cable.
FIG. 2 is a schematic diagram showing a submarine optical cable manufacturing apparatus, and FIGS. 3 and 4 are explanatory diagrams for measuring the shear peel strength of a compound. In the figure, 1 is an optical fiber unit, 2 is a metal pressure layer, 3 is a tensile strength wire, E is a gap, 13 is a dividing piece assembly and compound filling device, 14 is an assembly die, 18a, 18b, 19a, and 19b are compounds Reservoir, 20 indicates a pump.

Claims (1)

[Claims] 1. A two-component curing type polyurethane resin consisting of a main resin mainly composed of a polyolefin polyol and a prepolymer whose curing agent is synthesized by reacting the polyolefin polyol with an excess of diisocyanate is used around the optical fiber unit and the cable. A submarine optical cable characterized by filling the voids around the tensile strength member.