JPH11326725A - Spacer or unit type optical cable and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the longitudinal shrinkage of a unit with respect to a change in environmental temp. SOLUTION: The unit type spacer 10 erected with a pair of side walls 13a on a base 13b of a cross-sectional shape is continuously produced by arranging one piece each of arom. polyamide fibers as tension members 12 in side wall parts and extrusion coating the outer periphery thereof with a high-density polyethylene resin having a melt index(MI) of 0.1 g/10 minutes and a m.p. of 131 deg.C. This spacer is taken up on a drum. This unit type spacer 10 is introduced into a hot air heating vessel in which dry air of 250 deg.C is passed at a length 4 m. The spacer is then heat-treated at a line tension of 20 g and a rate of 10 m/min and is in succession cooled and taken up. The thermal shrinkage rate after lapse of one hour by resting the unit type spacer 10 still in a free state at 70 deg.C is 0.34% and the shrinkage in its longitudinal direction may be diminished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spacer for a unit type optical cable and a method for manufacturing the same, and more particularly, when such a spacer is used for an optical cable, a change in the dimension of the spacer due to a change in environmental temperature is small, and The present invention relates to a technology capable of stabilizing transmission performance.

[0002]

2. Description of the Related Art An optical fiber is accommodated in an outer periphery of a tensile strength member or a spacer having a plurality of spiral grooves, and one or two optical fiber accommodating grooves are provided on an outer periphery of a spacer which is wound around the outer periphery. An optical cable having a structure in which a plurality of spacers (hereinafter, sometimes referred to as unit-type spacers) are twisted is known.

[0003] In particular, an optical cable twisted while alternately reversing the twisting direction of the unit-type spacer is excellent in the intermediate branching property of the optical fiber, and is expected to expand demand in the future.

The unit-type spacer is mainly made of a crystalline thermoplastic resin. In order to prevent the optical fiber from being accommodated when the cable is formed or the tension applied when the unit-type spacer is twisted, elongation does not occur. , And often has a tensile strength member.

[0005] The strength member has a thin structure in which the unit type spacer itself has a side wall of 1.0 mm and a bottom portion of about 0.8 mm, and prevents deformation of the unit type spacer due to too strong rigidity of the strength member during twisting. In order to avoid this, an ultrafine FRP in which high-strength fibers themselves or reinforcing fibers are aligned in the longitudinal direction is often used.

However, the conventional unit-type spacer having such a structure has the following technical problems.

[0007]

That is, although the above-described tensile strength member is excellent in the effect of suppressing elongation in the tensile direction, in the case of high-strength fiber, there is almost no suppression force against compression in the longitudinal direction. Even in the case of the FRP,
In general, the modulus of elasticity in the compression direction is as small as a fraction of that in the tensile direction, and its effect is hardly expected due to its ultrafineness.

On the other hand, an optical fiber cable is often laid in a place where a temperature change occurs. In particular, when the optical fiber cable is laid outdoors, the optical transmission state may not change in a temperature range of −30 to + 70 ° C. is necessary.

However, when the optical fiber cable using the unit-type spacer is placed in such an environment, the optical transmission performance may be reduced. This is considered to be caused by the fact that in a unit type spacer made of a crystalline thermoplastic resin, crystallization proceeds due to a temperature change, and the unit type spacer shrinks in the longitudinal direction.

In other words, when twisted in one direction, the longitudinal shrinkage, which should have been suppressed, is twisted while being alternately inverted, so that longitudinal shrinkage in a form in which the twist of the inverted portion is loosened is possible. It is considered that the transmission loss increased because the twist pitch and the reversal angle of the unit-type spacer that were initially set were shifted.

Therefore, in the present invention, as an optical cable,
In use, even if the unit type spacers are twisted while being alternately inverted, the longitudinal shrinkage in the form of loose twisting of the inverting part causes shrinkage in the longitudinal direction against changes in environmental temperature. It is intended to provide a unit type optical cable spacer.

[0012]

In order to achieve the above object, the present invention relates to a unitary optical cable spacer made of thermoplastic resin having one or two optical fiber receiving grooves. Was made of polyethylene, and the longitudinal heat shrinkage after 1 hour at 70 ° C. was 0.4% or less. Further, in the above-mentioned unit-type optical cable spacer, as a more preferred embodiment, the longitudinal heat shrinkage after 1 hour at 70 ° C. is set to 0.2% or less. Further, a tensile strength wire is supplied to a crosshead die of a melt extruder, a thermoplastic resin is extruded from a die having a predetermined shape on an outer periphery thereof, and then cooled and solidified to form a unit type optical cable spacer having one or two grooves. After molding, 60
A method for manufacturing a spacer for a unit type optical cable, wherein the heat treatment is performed at a temperature of not less than ° C and not more than the melting point of the thermoplastic resin.
Further, a method for producing a spacer for a unit type optical cable, wherein the heat treatment is performed on the spacer at a temperature of 60 ° C. or more and a melting point of the thermoplastic resin or less and a line tension of the spacer is 100 g or less. In the method of manufacturing a spacer for a unit-type optical cable according to the present invention, a tension measuring machine is installed in the manufacturing process, and the tension of the optical fiber spacer during the heat treatment can be constantly measured by the tension measuring machine.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
It does not limit the scope of the invention.

FIG. 1 shows an embodiment of a unit type optical cable spacer according to the present invention.

The unit type optical cable spacer 10 shown in FIG. 1 includes a strength member 12 and a side wall 1 formed by coating a thermoplastic resin 13 on the outer periphery of the strength member 12 by extrusion molding.
The section 3a and the bottom 13b are formed in a substantially concave cross section.

The tensile strength member 12 has a high strength, a high elastic modulus, a low elongation, and an organic fiber (for example, an aromatic polyamide fiber, an aromatic polyamide fiber, an aromatic polyamide fiber, etc.) which does not easily shrink due to contact during the melt extrusion of the thermoplastic resin 13 constituting the main body. Group polyester, polyarylate fiber, polybenzoxazar (PBO) fiber, polyamide, polyester, vinylon, etc., inorganic fiber (glass fiber, carbon fiber, ceramic fiber, etc.) and a combination thereof, and these fibers A thin FRP wire or the like hardened by impregnating with a curable resin such as a vinyl ester resin or an unsaturated polyester resin is placed in the side wall 13a or the bottom portion 13b in an embedded manner.

The thermoplastic resin 13 constituting the side wall 13a and the bottom portion 13b is made of polyethylene and has a temperature of 70.degree.
After a lapse of time, the heat shrinkage in the longitudinal direction of the spacer is 0.4% or less.

The heat treatment for suppressing the thermal shrinkage after 0.4 hour at 70.degree. C. is carried out by producing the spacer 10 for the unit type optical cable and then forming the thermoplastic resin at 60.degree. 13 in a heating bath set at a temperature below the melting point, preferably with a line tension of 10
What is necessary is just to insert continuously with 0 g or less, to stay for a predetermined time, and to perform heat treatment.

The line tension means the unit type optical cable spacer 10 in the heat treatment step shown in FIG.
After the heat treatment in step 2, the tension is measured and detected before leaving the heating tank 22, passing through the cooling tank 23, and being taken off by the take-off machine 27.

In order to set the line tension to 100 g, the unit type optical cable spacer 10 in the heat treatment tank 22 is required.
It is necessary to consider the heat shrinkage force of
Before, the unit type optical cable spacer 10 is supplied in a loosened state, that is, overfeeding.

For this reason, a guide substantially horizontal to the center (running center) of each device, for example, a roller guide such as a roller conveyor, a belt conveyor, a sliding plate having a low coefficient of friction, etc. are arranged in front of the heat treatment tank 22. Accordingly, it is necessary to prevent the unit-type optical cable spacer 10 from hanging down from its traveling center by its own weight, thereby preventing the line tension from increasing.

The heating means in the heat treatment tank 22 includes hot air, dry heat using a far-infrared heater or the like, hot water, wet heat using a liquid heat medium, or a contact-type heating roller. Dry heat that does not require heat medium removal treatment or the like is more preferable.

The reason why the increase in transmission loss is suppressed when the unit-type spacer of the present invention is used is presumed to be generally as follows.

In general, when a crystalline thermoplastic resin is melt-molded, crystallization is not completely performed during the cooling process, and crystallization proceeds with time or by heat treatment. However, since shrinkage in the longitudinal direction occurs due to volume shrinkage during crystallization, a unit type spacer having no restraining force in the compression direction is used, and an optical fiber cable having a structure in which this is twisted in an SZ shape is a unit type spacer. Due to the shrinkage of the spacer, the untwist occurs and the transmission loss increases.

In the present invention, since the crystallization of the constituent resin of the unit-type spacer body is advanced in advance by heat-treating the unit-type spacer, crystallization due to a temperature change after forming the cable can be suppressed, and the longitudinal direction can be suppressed. Since the shrinkage or the like is suppressed, it is possible to prevent the transmission loss of the optical fiber mounted on the unit type spacer from increasing.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to preferred examples, but the scope of the present invention is not limited to the following examples.

Example 1 Two aromatic polyamide fibers (Kevlar manufactured by DuPont) 1140d to be used as the tensile member 12 were introduced into a crosshead die of a melt extruder, and were taken up at a speed of 15 m / min. Melt index (MI) is 0.
17 g of high-density polyethylene resin (manufactured by Mitsui Petrochemical; Hyzex 6300M) having a melting point of 131 ° C. at 1 g / 10 minutes.
Extrusion coating was performed at 0 ° C., and a unit-shaped spacer 10 having a cross-sectional shape shown in FIG. 1 was continuously manufactured and wound around a drum.

The obtained unit-type spacer 10 has a substantially U-shaped cross section having a pair of side walls 13a erected from both ends of a bottom portion 13b and an opening side, and has an outer width of 6.9 mm. The bottom width was 5.2 mm, the height was 5.4 mm, the outer groove width was 4.8 mm, the inner groove width was 3.9 mm, and the groove depth was 4.6 mm.

Next, this unit type spacer 10 is
As shown in FIG. 2, the feeding unit 26 feeds the drum 20 out of the drum 20, and adjusts the speed of the pulling unit 26 so as to have an extra length on a guide roller 25 in which rollers are arranged horizontally. The drying air is led to a hot-air heating tank 22 having a length of 4 m through which the drying air flows.
Heat treatment was carried out at a constant speed of 10 m / min., Followed by cooling in a cooling tank 23 and winding on a drum by a winder 24.

In this heat treatment, the surface temperature of the unit type spacer at the outlet of the hot air heating tank 22 was measured.
At 70 ° C., the line tension measured by the tension measuring machine 28 was 20 g.

FIG. 3 shows the details of the tension measuring device 28 used for measuring the line tension. The tension measuring device 28 is located between the cooling tank 23 and the take-up side take-up device 27 and is used during the manufacturing process. It is installed and constantly measures the line tension of the unit type spacer 10.

The tension measuring device 28 shown in FIG. 1 includes a pair of guide rollers 28b and 28c rotatably supported on a support base 28a on a same axis at a predetermined interval.
And a tension detecting roller 28d provided between the guide rollers 28b and 28c. The tension detecting roller 28d is rotatably supported by a rod 28e, and the rod 28e is vertically movably mounted on a support 28a via a spring 28f.

An arm 28 is provided on the side surface of the rod 28e.
g is integrally provided, and a load cell 28h is sandwiched between the arm 28g and the support base 28a. An amplifier 28i and a meter 28j are electrically connected to the load cell 28h.

The unit type spacer 10 for which the line tension is measured is provided between the upper surfaces of the pair of guide rollers 28b and 28c, and the tension detecting roller 28d is mounted on the upper side of the spacer to sandwich the spacer 10. The load of the tension detecting roller 28 d is applied to the spacer 10.

In order to install the spacer 10 in this manner, each of the guide rollers 28b and 28c and the tension detecting roller 28d are provided with a concave groove into which the spacer 10 can be fitted.

When the line tension of the unit-type spacer 10 fluctuates, the tension detecting roller 28d moves up and down, and the load applied to the Rohto cell 28h changes due to the up / down movement. , The line tension of the spacer 10 is measured.

In this case, the relationship between the load and the line tension is
If a calibration curve is created in advance, it can be easily obtained. If the tension measuring device 28 is provided in the production line in this manner, the unit type spacer 10 to be produced can be used.
The line tension over the entire length of can be confirmed.

The wound unit type spacer 10 did not show any problematic changes in appearance and cross-sectional shape.

This unit type spacer 10 is
mm and cut it into a sample length to obtain a sample.
After leaving still for 1 hour in a gear oven,
The unit-type spacer was left standing for 0 minutes and cooled, and the length of the sample was measured to be 997.1 mm.
The heat shrinkage in the longitudinal direction was 0.34%.

On the other hand, the tension member 30 in which seven steel wires each having an outer diameter of 2 mm are twisted is disposed at the center, and the groove width is 4.6.
SZ type spiral having 10 spiral grooves 31 with a groove depth of 4.6 mm, an outer diameter of 24.3 mm, the twist direction of the grooves is alternately reversed, the reverse angle is 280 degrees, and the reverse pitch is 380 mm. Using a spacer 32, eight optical fiber tapes 33 are laminated in each groove by 10 pieces, and in a state where a total of 800 optical fibers are stored, a holding tape 34 is wound around the outer periphery thereof without any gap, as shown in FIG. A core cable 35 having a cross-sectional shape was manufactured.

Next, with the bottom portion 13b of the heat-treated unit-type spacer 10 obtained above facing the center side, the optical fiber tape 33 is disposed adjacently in the circumferential direction and has eight cores.
Are mounted on the outer circumference of the core cable 35 at a reversal angle of 280 degrees and a reversal pitch of 380 mm.
After twisting in a Z-shape, the holding tape 36
And a polyethylene sheath 37 is applied to the outer periphery thereof to form an outer diameter of 45 m having a substantially sectional shape shown in FIG.
2000m fiber optic cable 38m long, 200m long
I got

With respect to the optical fiber cable 38, the transmission loss at a wavelength of 1.55 μm of the optical fiber in the unit type spacer 10 was measured in a drum-wound state, and the optical fiber mounted on the fifteen unit type spacers was measured. Were in the range of 0.21 to 0.27 dB / km.

Thereafter, the optical fiber cable 38 was put into a heat cycle test room in a drum wound state,
When the transmission performance was re-measured after repeating the heat cycle 5 times in the temperature range from to + 70 ° C, the transmission loss value was
No significant change was observed in the range of 0.24 to 0.32 dB / km.

Embodiment 2 In contrast to Embodiment 1, as shown in FIG.
Only one aromatic polyamide fiber (Kevlar 1140d) is arranged at the center of the bottom 13b 'of the unit type spacer 10', and the set temperature of the hot air heating tank in the heat treatment is set at 300 ° C.
Under the same conditions as in Example 1, except for the above, a heat treated unit type spacer 10 'was obtained. The surface temperature of the unit-type spacer 10 ′ at the outlet of the hot-air heating tank was 90 ° C., and no problematic change was observed in the appearance and the cross-sectional shape of the unit-type spacer 10 ′. Further, the heat shrinkage of the unit type spacer 10 ′ after a lapse of 1 hour at 70 ° C. in a gear oven in the same manner as in Example 1 was 0.1%.
8%.

The table summarizes the measured optical transmission performance of the optical fiber mounted on the unit body of the optical cable before and after the heat cycle test under the same conditions as in Example 1.

Embodiment 3 The embodiment 3 is the same as the embodiment 1 except that the guide roller 25 shown in FIG. 2 makes the extra length longer and the unit-type spacer 10 is led to the hot-air heating tank 22 in the overfeed state. The unit-type spacer 10 was obtained under the conditions.

The line tension of the spacer 10 at the outlet of the hot-air heating tank was 10 g, and no problematic change in the appearance and the cross-sectional shape of the spacer 10 and no meandering at the time of winding the drum were observed.

Further, the spacer 10 of the third embodiment was placed in a gear oven in the same manner as in the first embodiment.
The heat shrinkage after one hour at 0 ° C. was 0.20%.

The table summarizes the measured values of the optical transmission of the optical fiber mounted on the unit body in the optical cable before and after the heat cycle test under the same conditions as in Example 1.

Comparative Example 1 A unit-type spacer was obtained in the same manner as in Example 1, except that the heat treatment of the unit-type spacer was not performed.

The heat shrinkage of this unit type spacer was 0.77% by the above-mentioned measuring method.

As a result of measuring the optical transmission performance of the optical fiber in the unit-type spacer accommodating portion of the optical fiber cable manufactured in the same manner as in Example 1 using this unit-type spacer, 0.21-0. Although it was 25 dB / km, it increased to 0.48 to 1.25 dB / km after 5 heat cycles at -30 ° C to + 70 ° C.

COMPARATIVE EXAMPLE 2 For the unit-type spacer using the same die as in Example 1, the heat treatment conditions were as follows: the processing speed of the unit-type spacer was reduced to half of 5 m / min, and the set temperature of the hot air heating tank was set to 2
After heat treatment at 50 ° C., it was cooled and wound up. The surface temperature of the unit-type spacer body at the outlet of the hot-air heating tank is 135.
° C, and the cross-sectional shape of the unit-type spacer after winding has an outer width of 5.2 mm, a bottom width of 4.5 mm, and a height of 4.
Changes of 6 mm, groove outer width of 2.8 mm, groove inner width of 3.2 mm, and groove depth of 3.6 mm were observed.

Comparative Example 3 In contrast to Example 1, the guide roller 25 shown in FIG. 2 was not installed, and the take-up device 26 and the hot air heating tank 22 were hung down below the running center of the hot air heating tank 22 so as to be suspended. A unit spacer 10 was obtained under the same conditions as in Example 1 except that the heat treatment for guiding was performed. The line tension of the unit-type spacer 10 at the outlet of the hot-air tank was 400 g, and no problematic change in appearance or cross-sectional shape was observed.

However, the heat shrinkage of the unit-type spacer 10 of Comparative Example 3 measured by the same method as described above was 0.54%.

Further, as shown in the table, when the optical fiber was mounted on the optical cable and heat cycled, the transmission loss increased as compared with the embodiment.

In the first, second, and third embodiments, the spacer is used as the twisting core. However, a unit-type spacer is twisted around the outer periphery of a linear rod-shaped strength member. Even so, the effect remains the same.

In the embodiment, the so-called off-line system, in which the unit spacer is once wound around a drum, and then the unit spacer is fed out from the drum and supplied to a hot-air heating tank, is also used in the embodiment. As an example, of course, an on-line method in which a tensile strength body is extruded and coated with a polyethylene resin and then directly guided to a heating tank and subjected to heat treatment can also be employed.

Further, the manufacturing method of the present invention is not limited to the one shown in FIG. 1 in which the storage groove for the optical fiber is not only one U-shaped cross-section, but also the storage groove for the optical fiber is a two-shaped H-shaped cross-section. Can also be applied.

[0060]

[Table 1]

[0061]

As described in detail in the above embodiments, the unit type optical cable spacer according to the present invention is subjected to a heat treatment under a predetermined condition and a predetermined measurement to eliminate the influence of heat shrinkage in a practical temperature range. Since the heat shrinkage rate under the conditions is within a certain range, an optical fiber is mounted on this unit type spacer to form an optical cable, and even after a heat cycle that assumes a practical environment temperature, transmission loss does not increase, making it extremely practical. Is high.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a unit type optical cable spacer according to the present invention.

FIG. 2 (A) is an explanatory view of one example of a heat treatment method for a unit type optical cable spacer according to the present invention. (B) It is a top view for explaining the state of the spacer for unit type optical cables before a hot air heating tank.

FIG. 3 is a detailed view of the tension measuring machine shown in FIG.

FIG. 4 is a cross-sectional view showing one embodiment of an optical cable using the unit type optical cable spacer of the present invention.

FIG. 5 is a cross-sectional view showing another embodiment of the unit type optical cable spacer according to the present invention.

DESCRIPTION OF SYMBOLS 10 Unit-type optical cable spacer 12, 12 'Tensile body 13, 13' Unit-type spacer body 13a, 13a 'Side wall 13b, 13b' Bottom 20 Roll drum 21 Heat source 22 Hot air heating tank 23 Cooling tank 24 Take-up drum 25 Guide rollers 26, 27 Take-up machine 28 Tension measuring machine 30 Tension member 31 Spiral groove 32 Spiral spacer 33 Tape core wire 34 Holding winding tape 35 Core cable 36 Holding winding tape 37 Sheath 38 2000 core optical cable

Claims (5)

[Claims] 1. A unit type optical cable spacer made of a thermoplastic resin having one or two optical fiber storage grooves, wherein the thermoplastic resin of the unit type optical cable spacer main body is made of polyethylene and is heated at 70 ° C. for one hour. A spacer for a unit type optical cable, wherein a longitudinal heat shrinkage after passage is 0.4% or less. 2. The spacer for a unit type optical cable according to claim 1, wherein the heat shrinkage in the longitudinal direction when heat-treated at 70 ° C. for 1 hour or more is 0.2% or less. 3. A tensile strength wire is supplied to a crosshead die of a melt extruder, a thermoplastic resin is extruded from a die having a predetermined shape on an outer periphery thereof, and then cooled and solidified to form a unit type light having one or two grooves. After molding the fiber spacer,
A method for producing a spacer for a unit type optical cable, comprising: performing a heat treatment on the spacer at a temperature of 60 ° C. or higher and a melting point of the thermoplastic resin or lower. 4. The method according to claim 3, wherein the line tension during the heat treatment is set to 100 g or less. 5. A unit according to claim 4, wherein a tension measuring machine is installed during the manufacturing process, and the tension measuring machine constantly measures a line tension of the optical fiber spacer during the heat treatment. For manufacturing spacers for optical fiber cables.