JPH09105844A - Optical fiber protective pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber protective pipe which has the excellent mechanical characteristics required as a pipe for protecting an optical fiber and has the high threshold values of the insertion distance and insertion speed of the optical fiber units. SOLUTION: Plural pieces of ribs 2...2 consisting of a thermoplastic resin contg. 0.1 to 30wt.% lubricant are laminated on the inside surface of the pipe 1 consisting of the thermoplastic resin along its longitudinal direction, by which the friction coefft. of the inside surface of the pipe is lowered without degrading the mechanical characteristics of the pipe itself.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tube for housing and protecting an optical fiber unit.

[0002]

2. Description of the Related Art A resin pipe such as PVC or PE is generally used as a conduit for accommodating and protecting an optical fiber unit.

As a method of installing the optical fiber unit, a construction method in which the above-mentioned resin pipe is laid in the soil in advance and the optical fiber unit is inserted into the conduit using air pressure or the like is widely used. Has been.

However, since each optical fiber unit has a limit tension and the tension due to the friction between the outer surface of the optical fiber unit and the inner surface of the resin pipe at the time of insertion must be less than the limit tension, the insertion distance is inevitable. Alternatively, the insertion speed must be set to a certain value or less.

As a means for solving this, Japanese Patent Publication No. 4-2
Japanese Patent No. 3484 discloses a method of reducing frictional resistance on the inner surface of a pipeline by adding a lubricant (particularly erucylamide) to the material of the pipeline, and JP-A-4-36260.
Japanese Patent Publication No. 2 discloses a method of similarly reducing the frictional resistance on the inner surface of the conduit by forming a pipe by mixing polyethylene with silicone graft polyethylene as a lubricant. Further, Japanese Utility Model Laid-Open No. 63-49502 discloses a method of reducing frictional resistance on the inner surface of the pipe by forming a plurality of grooves on the inner wall of the pipe along the longitudinal direction of the pipe. .

[0006]

By the way, the above-mentioned Japanese Patent Publication No. 4-23484 and Japanese Unexamined Patent Publication No. 4-362602.
According to the method described in the publication, since the lubricant is added to the resin itself forming the conduit, the earth pressure resistance or creep property required when burying in soil required as an optical fiber protection tube is deteriorated. Such problems occur. Further, the amount of lubricant used is large, which is disadvantageous in terms of material cost.

On the other hand, according to the method disclosed in Japanese Utility Model Laid-Open No. 63-49502, when the surface property of the convex portion between the grooves on the inner wall of the conduit is poor, the friction resistance cannot be greatly reduced, On the contrary, there is a possibility that the frictional resistance may increase.

An object of the present invention is to reduce the frictional resistance on the inner surface of the pipe line without lowering the mechanical properties (for example, earth pressure resistance, creep properties, etc.) required as a pipe for protecting the optical fiber, and thus the optical fiber unit. An object of the present invention is to provide an optical fiber protection tube capable of significantly improving the insertion distance and the insertion speed of the optical fiber.

[0009]

In order to achieve the above object, the optical fiber protection tube of the present invention comprises a thermoplastic resin containing 0.1 to 30% by weight of a lubricant on the inner surface of the tube made of a thermoplastic resin. Are characterized by being formed along the length of the tube.

Here, in the present invention, examples of the thermoplastic resin used for the pipe portion and the rib portion include polyethylene, polypropylene, polyvinyl chloride, ethylene-propylene copolymer, ABS resin, polystyrene, polyamide such as 66-nylon, Polyester such as polyethylene terephthalate, polycarbonate, polyacetal, polyphenylene sulfide and the like can be mentioned. These resins may be used alone or in combination of two or more. Further, the resin used for the tube portion and the resin used for the rib portion are preferably the same type in consideration of the adhesiveness.

Among these resins, polyethylene having a particularly small friction coefficient is preferable, and in consideration of the earth pressure resistance when laying in soil, the density is 0.940 to 0.970.
Medium density polyethylene or high density polyethylene having g / cm ³ is more preferable.

The lubricant used in the rib portion of the present invention is not particularly limited as long as it improves lubricity by adding it to a thermoplastic resin, and examples thereof include organopolysiloxane, silicone graft polyethylene, and tetrafluoride. Examples thereof include ethylene resin powder, waxes such as polyethylene wax, higher fatty acids such as stearic acid or salts thereof, paraffins and phthalic acid diesters. Among these, organopolysiloxanes having an MRF based on JIS K7210 (test condition 6) of about 0.5 to 70 g / 10 minutes are less likely to be detached due to friction when the optical fiber unit is inserted, and have a large sliding effect. Therefore, it is particularly preferable.

In the present invention, the number of parts of the rib-forming resin composition is 0.1 to 30 parts by weight, preferably 0.3 to 10 parts by weight, relative to 100 parts by weight of the thermoplastic resin.
Parts by weight. If the number of blended parts is less than 0.1 part by weight, the effect of improving lubricity does not appear, and conversely, if the number of blended parts is 30 parts by weight or more, problems such as a marked decrease in moldability occur.

In the present invention, the ribs laminated on the inner surface of the pipe may be arranged and shaped as desired as long as they are arranged along the longitudinal direction of the pipe. For example, the ribs may be linear in the longitudinal direction of the pipe. Those arranged, or JP-A-3-12260
Examples thereof include those arranged in a spiral shape having an angle with respect to the longitudinal direction as described in Japanese Patent Publication No. 3, and those arranged in a wavy shape in which the angle with respect to the longitudinal direction is not constant. Further, the shape of the tip of the rib is not particularly limited and may be angular or rounded. Further, the height of the ribs and the distance between the ribs are arbitrary, and these respective dimensions can be appropriately designed according to the specifications (diameter, weight, etc.) of the optical fiber unit arranged in the tube. However, it is preferable that the surface of the optical fiber unit is dimensioned so as not to contact the concave portion between the ribs.

The thermoplastic resin used in the present invention may contain, if necessary, stabilizers, antioxidants, flame retardants,
Antistatic agents, pigments, fillers, processing aids and the like may be added.

[0016]

By including a lubricant only in a plurality of ribs laminated on the inner surface of the tube, the friction coefficient of the inner surface of the tube can be lowered without lowering the mechanical characteristics of the tube itself. Moreover, since it is sufficient to add the lubricant only to the ribs, the lubricant used can be small.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION First, the optical fiber protection tube of the present invention can be manufactured using the process shown in FIG.

The manufacturing process shown in FIG. 1 includes a first extruder 11, a second extruder 12, a mold 13, and a spray water tank 14.
In addition, the take-up machine 15 is used. Mold 13
As shown in FIG. 2, the two resin inlets 13a and 13
b, each connected to a first extruder 11 and a second extruder 12. Each resin inlet 13a and 13b
Respectively communicate with the resin flow paths 13c and 13d, and the resin flow path 13c is provided on the outer peripheral surface of the mold core 13e.
Further, the resin flow path 13d is guided to the tip of the mold core 13e. On the outer peripheral surface of the die core 13e, rib forming grooves are formed at a constant pitch in the circumferential direction, and the ribs 2 ... 2 having the shape shown in FIG. It is designed to be continuously extruded.

The first extruder 11 is connected to the mold 13 via an adapter 16. Further, the second extruder 12 (for rib extrusion) is additionally provided with a press-fitting pump 17 and a lubricant container 18 for supplying a lubricant to the hopper 12a.

In the above manufacturing process, the hopper 11a of the first extruder 11 is formed with a thermoplastic resin for forming a pipe portion, and the hopper 12a of the second extruder 12 is formed with a lubricant. By supplying the thermoplastic resin for each of them, a molded product shown in FIG. 3, that is, an optical fiber in which a plurality of ribs 2 ... 2 linearly extending along the longitudinal direction of the tube are laminated on the inner surface of the tube. The protection tube 1 can be obtained.

[0021]

EXAMPLES Examples 1 to 3 and Comparative Examples 1 to 2 The manufacturing process shown in FIG. 1 was used. Barrel temperature is 16
The first extruder (single screw extruder, set to 0 ° C,
φ = 65mm, L / D = 35) hopper, high density polyethylene (Mitsui Petrochemical Co., Ltd. Hi-Z 630
0 M, MFR = 0.11 g / 10 min.) Was supplied. At the same time, the second extruder (meshing type co-rotating twin-screw extruder, φ = 47) with the barrel temperature set at 160 ° C.
mm, L / D = 35) hopper, high density polyethylene (Mitsui Petrochemical Co., Ltd. Hi-Zex 6300M, M
FR = 0.11 g / 10 min.) And dimethylpolysiloxane (MFR = 35 g / 10 min.) Were fed. Dimethylpolysiloxane was press-fitted using a Mono pump (manufactured by Hyōjin Equipment Co., Ltd.). The number of each compounding part is shown in Table 1 below.

Then, the two kinds of resin melts respectively melt-kneaded by the above two extruders are merged in the mold 13 having the structure shown in FIG. 2, and the inside of the pipe as shown in FIG. 3 is extruded. A pipe having an inner diameter of 50 mm and an outer diameter of 60 mm was obtained with a structure in which a plurality of ribs were laminated on the surface.

On the pipe obtained by the above extrusion molding,
The optical fiber unit shown in FIG. 4, that is, composed of four optical fiber core wires 41, a tension member 42 and a buffer layer 43 at the center thereof, and an outer layer covered with a PE sheath 44 has an outer diameter of 10 mm and a unit weight of 90 kg / Using a winch of the method shown in FIG. 5, a strain gauge type tension type load cell (manufactured by Kyowa Denki Co., Ltd.) is used for a km optical fiber unit (allowable tension 1500N) at a constant speed of 50 m / min.
TL-500KF) was inserted while measuring the take-up force.
Then, the measurement was stopped when the pulling force reached the allowable tension of the optical fiber unit, and the insertion distance at that time was shown as the limit insertion distance in Table 1 below.

Further, the insertion speed was variously changed, and when the insertion distance reached 400 m, the insertion speed at which the pulling force reached the allowable tension of the optical fiber unit was found, and the value is set as the limit insertion speed in Table 1. Indicated.

Further, based on JIS K7113, a dumbbell-shaped sample was punched from the obtained pipe in the pipe axis direction, and the yield tensile stress was determined by a tensile test and shown in Table 1. Furthermore, the obtained pipe was cut along a plane passing through the tube axis, and the appearance of the rib surface was visually evaluated. A sample with a smooth surface and no aggregation of lubricant was found, and a sample with aggregation of lubricant or surface swelling was marked as X.
The results are shown in Table 1.

In the winch (FIG. 5) used for measuring the pulling force, the pulling line L wound around the pulling reel 51 is inserted into the optical fiber protection tube P to be tested, and the pulling line L is Is used to draw the optical fiber unit U from the delivery reel 52 into the optical fiber protection tube T, and a load cell for measuring the pulling force is arranged at the connection point between the pulling line L and the optical fiber unit U. To be done.

[0027]

[Table 1]

Example 4 The manufacturing process shown in FIG. 1 was used. However, the press-fitting pump 17 was removed. In the hopper of the first extruder (meshing type counter-rotating twin-screw extruder, φ = 47 mm, L / D = 35) with the barrel temperature set to 180 ° C., add PVC to the hopper.
(Polymerization degree manufactured by Tokuyama Sekisui Co., Ltd. 900%) was supplied. At the same time, a second extruder (meshing type counter-rotating twin-screw extruder, φ = 47) in which the barrel temperature was set to 180 ° C.
mm (L / D = 35), PVC (manufactured by Tokuyama Sekisui Co., Ltd., polymerization degree: 900%) and stearic acid were supplied to a hopper having a size of 35 mm. The number of blended parts is shown in Table 2 below.

The two types of resin melts melt-kneaded by the above-mentioned two extruders are brought together by a mold (having the structure shown in FIG. 2) set at 160 ° C., and extrusion molding is performed as shown in FIG.
A pipe having an inner diameter of 50 mm and an outer diameter of 60 mm was obtained with a structure in which a plurality of ribs were laminated on the inner surface of the pipe as shown in FIG.

The pipe obtained by the extrusion molding was used in Example 1.
The evaluation was performed in the same manner as above, and the results are shown in Table 2. Comparative Example 3 The manufacturing process shown in FIG. 6, that is, the process of supplying the resin melt to the die 103 from one extruder 101 was used.

Extruder with barrel temperature set at 160 ° C. (meshing type co-rotating twin screw extruder, φ = 47)
mm, L / D = 35) hopper, high density polyethylene (Mitsui Petrochemical Co., Ltd. Hi-Zex 6300MM
FR = 0.11 g / 10 min.) And dimethylpolysiloxane (MFR = 35 g / 10 min.) Were fed. Dimethylpolysiloxane was press-fitted using a Mono pump (manufactured by Hyōjin Equipment Co., Ltd.). The number of parts to be mixed is shown in Table 2. Then, after melt-kneading in the extruder, the resin melt is extruded from a mold (FIG. 7) kept at 150 ° C., and has a shape having ribs on the inner surface of the pipe as shown in FIG. 3 and an inner diameter of 50 mm, Outer diameter 60 mm
Got the pipe.

The pipe obtained by the extrusion molding was used in Example 1.
The evaluation was performed in the same manner as above, and the results are shown in Table 2. As shown in FIG. 7, the mold 103 used in this comparative example has one resin inflow port 103a, and a groove for rib forming has a constant pitch on the outer peripheral surface of the inner mold core 103e. The ribs are formed at the same time as the pipe portion by extruding a part of the resin melt from the extruder 101 into each of the forming grooves.

Comparative Example 4 The manufacturing process shown in FIG. 5 was used. However, the press-fitting pump was removed. Extruder with barrel temperature set at 160 ° C (single screw extruder, φ = 65 mm, L / D = 3
5) High-density polyethylene (Mitsui Petrochemical Co., Ltd. Hi-Zex 6300 M.MFR = 0.11 g /
10 min.) Was supplied. Then, after melt-kneading in the extruder,
Mold the resin melt at 150 ° C (Figure 7)
Was extruded, and a pipe having an inner diameter of 50 mm and an outer diameter of 60 mm was obtained as shown in FIG.

The pipe obtained by the extrusion molding was used in Example 1.
The evaluation was performed in the same manner as above, and the results are shown in Table 2. Comparative Example 5 The manufacturing process shown in FIG. 5 was used. However, the press-fitting pump was removed.

Extruder with barrel temperature set at 180 ° C. (meshing type counter rotating twin screw extruder, φ = 47)
mm, L / D = 35) hopper was supplied with PVC (Degree of polymerization of Tokuyama Sekisui Co., Ltd. 900%). After melt-kneading in the extruder, the resin melt is extrusion-molded from a mold set at 160 ° C. (FIG. 7), and has a shape having ribs on the inner surface of the tube as shown in FIG. A pipe having a diameter of 60 mm was obtained.

The pipe obtained by the extrusion molding was used in Example 1.
The evaluation was performed in the same manner as above, and the results are shown in Table 2.

[0037]

[Table 2]

From the results shown in Table 1 and Table 2 above, the optical fiber protection tubes obtained in Examples 1 to 3 of the present invention are good in both the critical insertion distance and the critical insertion speed, whereas Comparative Example 1 In the case of the optical fiber protective tube obtained in step 1, that is, the one having a lubricant compounding part number of less than 0.1 parts by weight, the critical insertion distance and the critical insertion speed are low, and a sufficient sliding effect cannot be obtained, and the optical fiber obtained in Comparative Example 2 Protective tube, that is, the number of lubricant compounding parts is 3
It was confirmed that the amount of 0 parts by weight or more deteriorates the moldability.

Further, it was confirmed that the product obtained in Example 1 has excellent mechanical properties as compared with the optical fiber protection tube obtained in Comparative Example 3 (where the lubricant is also added to the tube portion). It was Furthermore, in Examples 1 to 3, it was confirmed that the limit insertion distance and the limit insertion speed were significantly improved with respect to the optical fiber protection tube obtained in Comparative Example 4 (one containing no lubricant). .

Furthermore, from the results of Example 4 and Comparative Example 5, it was confirmed that even if the thermoplastic resin used for the tube portion and the rib portion was changed, the same effect as above could be obtained.

[0041]

As described above, according to the optical fiber protection tube of the present invention, the inner surface of the tube made of thermoplastic resin is
Since ribs made of a thermoplastic resin containing 0.1 to 30% by weight of a lubricant are laminated along the longitudinal direction of the pipe, the insertion distance and the insertion length of the optical fiber unit can be maintained without deteriorating the mechanical characteristics of the pipe itself. The speed can be greatly improved as compared with the conventional one. Moreover, the amount of lubricant used is small, and the above-mentioned effects can be achieved at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a manufacturing process of an optical fiber protection tube of the present invention.

FIG. 2 is a partially cutaway sectional view showing a structure of a mold used in the manufacturing process.

FIG. 3 is a cross-sectional view showing the structure of an optical fiber protection tube obtained by the manufacturing process of FIG.

FIG. 4 is a diagram showing a structural example of an optical fiber unit which is inserted into an optical fiber protection tube of the present invention.

FIG. 5 is a diagram showing an example of a method of inserting an optical fiber unit into an optical fiber protection tube.

FIG. 6 is a schematic view showing a manufacturing process of the optical fiber protection tube used in Comparative Examples 3 to 5 of the present invention.

FIG. 7 is a partially cutaway sectional view showing the structure of a mold used in the manufacturing process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber protection tube 2 ... 2 Rib 11 1st extruder 11a hopper 12 2nd extruder 12a hopper 13 Mold 14 Spray water tank 15 Pulling machine 17 Press-fitting pump 18 Lubricant container

Claims (1)

[Claims] 1. An optical fiber in which a plurality of ribs made of a thermoplastic resin containing 0.1 to 30% by weight of a lubricant are formed on the inner surface of the pipe made of a thermoplastic resin along the longitudinal direction of the pipe. Protection tube.