JPH0431363B2 - - Google Patents

Description

[Detailed description of the invention]

<<Industrial Application Field>> The present invention is used as an element of an optical fiber cable, and is used to collect and protect a plurality of optical fibers.
The present invention relates to a supporting spacer and a manufacturing method thereof. <Prior art and its problems> This type of spacer uses a single steel wire, twisted steel wire, etc. as a tensile strength wire, and forms a spacer body around the outer periphery of a thermoplastic resin. It is known to have a spiral groove, and its manufacturing method involves inserting a tensile strength wire into a crosshead die and melting and extruding the thermoplastic resin from the die while rotating a die with various mouth shapes. A method is known in which the coating is coated with a powder and then cooled and solidified. In such a conventional manufacturing method, for example, a twisted steel wire is used as the tensile strength wire, high-density polyethylene is used as the resin for forming the spacer body, and the spacer is manufactured by extrusion coating. Therefore, in the spacer having this configuration, the longitudinal bonding force between the tensile strength wire and the spacer main body is obtained by the unevenness based on the twisted structure of the twisted steel wire and the extrusion-coated thermoplastic resin entering the unevenness. , which relied exclusively on the locking force of so-called anchor adhesion. However, in such anchor bonding,
Because the bonding force between the tensile strength wire and the spacer body was insufficient, the following problems occurred. In other words, especially when a soft resin such as polyethylene or polypropylene homopolymer is used for the spacer body, the bonding or adhesion between the tensile strength wire and the spacer body becomes insufficient, and it is necessary to install the optical fiber in the groove of the spacer. During use, the thermoplastic resin of the spacer body expands and contracts due to temperature changes, causing microbending loss in the optical fiber, which could increase transmission loss. This phenomenon occurs because the above-mentioned thermoplastic resin has a larger linear expansion coefficient than the tensile strength line, and the thermal stress that expands and contracts in the longitudinal direction in response to changes in the environmental temperature of the spacer body is caused by the anchor adhesion between the tensile strength line and the spacer body. This is thought to be due to the fact that the spacer body becomes larger than the locking force, and that when the spacer body is molded, the thermoplastic resin undergoes thermal contraction due to the influence of residual strain when it cools and solidifies. In particular, the locking force in the anchor bonding described above is
It is thought that at high temperatures, the thermoplastic resin part becomes soft and easily deforms over the unevenness caused by the twisted structure of the tensile strength wires, reducing the locking force. Here, in order to solve this problem and increase the locking force in anchor bonding, it is possible to use a hard or heat-resistant thermoplastic resin as the forming resin for the spacer body, but with this configuration, the tensile strength Although the bonding strength between the wire and the spacer body is improved, it lacks flexibility as a spacer for supporting optical fiber cables, causing handling problems when installing the optical fiber into the groove of the spacer and during installation work. do. [Object of the Invention] The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to minimize dimensional changes due to changes in environmental temperature, and to reduce adverse effects such as increased transmission loss of optical fibers. An object of the present invention is to provide a spacer for supporting an optical fiber and a method for manufacturing the same, which has a low possibility of causing damage and has flexibility suitable for installation. <Means for Solving the Problems> In order to achieve the above object, the present invention uses a tensile strength wire having a twisted structure and a hard and heat-resistant thermoplastic resin surrounding the tensile strength wire as an optical fiber supporting spacer. a primary coating layer consisting of a material having high compatibility with the thermoplastic resin on the outer periphery of the primary coating layer;
and a spacer body formed of a thermoplastic resin that is softer than the thermoplastic resin, and the primary coating layer is tightly packed into the uneven portion of the tensile strength wire having a twisted structure at the interface with the tensile strength wire, The spacer body and the primary coating layer are fused and bonded, and the spacer body is formed with a plurality of grooves for attaching optical fibers that extend continuously in the longitudinal direction. As a manufacturing method for an optical fiber supporting spacer, a tensile strength wire having a twisted structure is inserted into a crosshead die, a hard and heat-resistant thermoplastic resin is melted and extruded around the outer circumference of the crosshead die, and extruded to form a twisted structure. After forming a primary coating layer that closely covers the uneven portions of the tensile strength wire and has a coating thickness of at least 0.25 mm, a soft thermoplastic resin that has a high compatibility with the thermoplastic resin is used. The coating is characterized by forming a plurality of grooves extending in the longitudinal direction on the outer periphery of the coating layer. To explain in more detail, twisted steel wires, twisted wires of fiber-reinforced plastic, etc. are used as the above-mentioned tensile strength wires, and by twisting a plurality of wires together, an uneven twisted structure is formed on the surface, and a predetermined shape is formed. It is sufficient if it has tension. In addition, as the thermoplastic resin for the primary coating,
When used as an element of optical fiber cable, it must have stable heat resistance and hardness against environmental temperature changes, and a bending modulus of 150 Kg/mm ² or more and a flexural modulus of 18.6 Kg/cm ² under a load. The heat distortion temperature of 100
It is desirable to select from resins that have a temperature of ℃ or higher. Resins that satisfy these conditions include thermoplastic resins reinforced with reinforcing fibers such as glass fibers and carbon fibers, such as glass fiber reinforced polyethylene, polypropylene, and nylon, or thermoplastic resins reinforced with carbon fibers. resin and the like
Examples include ABS resin and various modified resins thereof reinforced with fibers. If a resin with a bending modulus of elasticity and a thermal deformation temperature lower than the values mentioned above is used as a support element for an optical fiber cable, it may be susceptible to changes such as expansion or thermal contraction due to environmental temperature changes during use. As a result, the locking force between the concave and convex portions of the twisted structure and the primary coating resin layer becomes insufficient, and the spacer body welded to the primary coating resin layer shrinks due to heat, causing optical fibers attached to the grooves of the spacer body to There is a risk that it will have a negative impact on In addition, the thickness of the primary coating layer made of the above-mentioned resin is
The spacer main body to be formed afterward must be approximately 0.5 mm larger in diameter than the apparent outer diameter of the tensile strength wires of the twisted structure, that is, the thickness of the thinnest part must be 0.25 mm or more. It is desirable from the point of view of welding and joining. On the other hand, the resin for forming the spacer body may be any resin that has high compatibility with the primary coating layer and can be fusion-bonded with the primary coating layer, but the functions required for the spacer body are as follows: Physical properties sufficient to separate each optical fiber or core wire and strength against radial lateral pressure are required. From these points of view, high-density polyethylene, low-density polyethylene, polypropylene, ABS, nylon 12, etc. homopolymers, and various modified resins or copolymers thereof. When flexibility is particularly required, a soft resin may be selected and used. The shape of the spacer main body is determined by the number of grooves, groove depth, groove width, outer diameter of the main body, parallel grooves, spiral grooves, etc., depending on the optical fiber design requirements. <<Operations and Effects of the Invention>> In the optical fiber supporting spacer of the present invention having the above-described structure, the uneven portions of the tensile strength wires having a twisted structure are closely filled with a primary coating layer made of a hard and heat-resistant thermoplastic resin. Therefore, the locking force due to the anchor adhesion between them is stable over a wide range of environmental temperature changes, and is particularly prevented from decreasing at high temperatures. In addition, the spacer body to which the optical fiber is attached is made of a thermoplastic resin that is softer than the resin of the primary coating layer. Since these resins have high compatibility with each other, the bonding strength between the primary coating layer and the spacer body can also be maintained high. Furthermore, according to the manufacturing method of the present invention, a spacer that provides the above-mentioned effects can be manufactured relatively easily, and since the outer periphery of the tensile strength wire is coated with thermoplastic resin in two stages, Residual distortion can be reduced. <<Examples>> Examples and comparative examples of the present invention will be described in detail below with reference to the accompanying drawings. (Example 1) Nine steel wires with a diameter of 0.38 mm were used as the tensile strength wire 1.
(3+6) twisted steel wires with an apparent outer diameter (envelope diameter connecting the outer periphery of each strand, hereinafter the same) of 1.2 mm are used, and after cleaning the surface with acetone and degreasing, cross After passing through the head die 2 and applying a primary coating layer 3 of glass fiber-reinforced polyethylene with a glass content of 15%, the tube is introduced into a cooling and solidifying tank 4, and then wound around a drum 5 to form a coating with an outer diameter of 2.2 mm. Core wire 7 was obtained. This strand 7 is further inserted into a crosshead die having a die corresponding to the cross-sectional shape of the spacer to be described later, and while rotating the die 8, high-density polyethylene (MI=0.3) is coated around the outer periphery of the core strand 7. Then,
It has 4 protrusions equally spaced at 5.1 mm and a root diameter of 2.4 mm.
After being coated to form a spacer body 9 with a spiral pitch of 120 mm, it is introduced into a cooling tank 10 filled with a refrigerant such as air or cooling water, where it is cooled and solidified, and then wound onto a drum 11. . The spacer 12 manufactured in this manner had the cross-sectional shape shown in FIG. 3, and the bonding strength between the spacer body 9 and the tensile strength wire 1 made of twisted steel wire was measured by the following method. That is, the end portion of the spiral spacer body 9 is 10 mm
Regarding the length, the thermoplastic resin part in the cross-sectional direction of the helical spacer main body 9 was brought into contact with the jig of the chuck part of a tensile tester, and the tensile shear bonding strength was measured by performing a tensile test at a tensile speed of 5 mm/min. The value was divided by the area of the apparent outer periphery of the tensile strength line 1 to obtain the bonding strength (pulling strength). The bonding strength of the spacer of this example measured by this measuring method was 42 kg/cm ² . In addition, a sample with a length of approximately 1 m was placed in a dry hot air oven at 60°C and 100°C, and left for 1 hour, then left at 23°C (room temperature) for 30 minutes, and then the length of the spacer body 9 was measured. (L) mm, and the heat shrinkage rate was measured using the following formula. Heat shrinkage rate = {(1000-L)/1000} x 100% In the sample of this example, the heat shrinkage rates at 60°C and 100°C were respectively 0%. Furthermore, a heat cycle of 1 hour at -35°C and 1 hour at 80°C was repeated 30 times, and the shrinkage rate was measured in the same way, and a value of 0.15% was obtained for this example. It was done. Furthermore, the flexibility of the spacer body 9 with the tensile strength line 1 arranged in the center was measured by the following means. The sample for measurement is semicircular with a diameter of 100 mm.
The repulsive force of this semicircular sample was measured using a spring balance. The value of the sample of this example measured by this measurement method was 0.15 kg. Note that all physical property values such as bonding strength in the following Examples and Comparative Examples are values measured by the method described above, and therefore description of the measurement method will be omitted hereafter. (Comparative Example 1) The same tensile strength wire 1 as in Example 1 was used, the secondary coating layer 3 was not formed, and after degreasing, it was inserted into the same crosshead die 8 as in Example 1. A spacer body 9 having the same shape was formed from high-density polyethylene (MI=0.3). That is, in Comparative Example 1, the spacer 12 was formed by omitting the step shown in FIG. 1 described in Example 1 above. As a result, the joint strength was 13Kg/cm ² at 60℃ and
The heat shrinkage rate at 100℃ is 0.1~0.15% and 0.3~
0.55%, heat shrinkage rate after heat cycle is 1.6%,
Flexibility was 0.15 kg, and all other properties except flexibility were inferior to Example 1 above. (Comparative Example 2) The configuration of the tensile strength wire 1, the size and shape of the spacer body 9, etc. are the same as those in Example 1 and Comparative Example 1, but the resin forming the spacer body 9 is used as the primary coating in Example 1. The spacer 12 was made of the same glass fiber reinforced polyethylene as in Comparative Example 1.
The following results were obtained when each characteristic was measured. In other words, the bonding strength is 44Kg/cm ² , 60℃ and
The thermal contraction rate at 100°C is 0%, and the thermal contraction rate after heat cycle is 0.1%, and these values are comparable to those in Example 1 above, but the flexibility is 0.35 kg. Therefore, spacers of this standard pose problems when forming and installing optical fiber cables. (Example 2) Steel wire with a diameter of 0.6 mm was used as tensile strength wire 1 (1+6)
A twisted steel wire with an apparent outer diameter of 1.8 mm is used in the structure of a book, and after cleaning the surface with acetone and degreasing it, it is inserted into the crosshead die 2 and heat resistant.
A primary coating layer 3 is formed with ABS (manufactured by Denki Kagaku Kogyo: trade name HS800), introduced into a cooling solidification tank 4, and then wound around a drum 5 to obtain a core strand 7 with a coating outer diameter of 3.0 mm. Ta. This strand 7 is further inserted into a crosshead die having a die corresponding to the cross-sectional shape of the spacer, which will be described later, and while rotating the die 8, the outer periphery of the core strand 7 is coated with modified ABS (manufactured by Ube Cycon, product name:
UKB440), the peak diameter is 13.0mm and the valley diameter is evenly spaced.
It has 6 protrusions of 6.8mm, and the spiral pitch is 150mm.
After coating the spacer body 9 to form a spacer body 9 having the following properties, it was introduced into a cooling bath 10 filled with a coolant such as air or cooling water, where it was cooled and solidified, and then wound onto a drum 11. The bonding strength of the spacer 12 obtained was as large as 85 Kg/cm ² , and the heat shrinkage rates at 60°C and 100°C and after the heat cycle were 0%, respectively.
Flexibility was 1.4Kg. (Comparative Example 3) The same tensile strength wire 1 as in Example 2 was used, the primary coating layer 3 was not formed, and after degreasing, the wire was inserted through the same crosshead die 8 as in Example 2. A spacer main body 9 having the same shape as in Example 2 was formed from the same modified ABS. That is, in Comparative Example 3, the spacer 12 was formed by omitting the step shown in FIG. 1 described in Example 2 above. As a result, the joint strength was 15Kg/cm ² at 60℃ and
Thermal contraction rate at 100℃ is -0.15% and -0.25, respectively.
%, the thermal shrinkage rate after heat cycle was 1.3%, and the flexibility was 1.2 kg, and all other properties except flexibility were inferior to Example 2, especially the bonding strength was less than 1/5. It was hot. (Comparative Example 4) The structure of the tensile strength wire 1, the size and shape of the spacer body 9, etc. are the same as those in Example 2 and Comparative Example 3, but the resin used to form the spacer body 9 was used as the primary coating in Example 2. A spacer 12 was formed using ABS having the same dimensions as Comparative Example 3, and various characteristics were measured, and the following results were obtained. In other words, the bonding strength is 87Kg/cm ² , 60℃ and
The thermal contraction rate at 100°C is 0%, and the thermal contraction rate after heat cycle is 0%, and these values are comparable to those in Example 2 above, but the flexibility is 3.5 kg. As it grows, the rigidity becomes too large,
There are problems when installing fiber optic cables. (Example 3) A steel wire with a diameter of 0.38 mm was used as the tensile strength wire 1 (3+
6) Use twisted steel wire with an apparent outer diameter of 1.2 mm twisted in the structure of the book, and after cleaning and degreasing the surface with acetone, insert it into the crosshead die 2 and insert it into the Teismo reinforced polypropylene (Dainichiseika Manufactured by: Product name
A primary coating 3 was formed using PPT1235), introduced into a cooling solidification tank 4, and then wound around a drum 5 to obtain a core strand 7 with a coating outer diameter of 2.2 mm. This strand 7 is further inserted into a crosshead die having a die corresponding to the cross-sectional shape of a spacer to be described later, and while rotating this die 8, a polypropylene-ethylene copolymer (Ube Made by Kosan (product name: J701H), it is coated to form a spacer body 9 having six protrusions equally spaced with a peak diameter of 5.5 mm and a valley diameter of 3.0 mm, with a spiral pitch of 200 mm. After that, it is introduced into a cooling tank 10 filled with a refrigerant such as air or cooling water, and is cooled and solidified.
After that, it was wound onto the drum 11. The bonding strength of the obtained spacer 12 was 35Kg/cm ² ,
The heat shrinkage rate at 60℃ and 100℃ is 0% respectively, the heat shrinkage rate after heat cycle is 0.05%, and the flexibility is
It was 0.2Kg. (Comparative Example 5) The same tensile strength wire as in Example 3 was used, the primary coating layer 3 was not formed, and after degreasing, the wire was inserted through the same crosshead die 8 as in Example 3. A spacer body 9 having the same shape was formed from polypropylene. That is, in Comparative Example 5, the spacer 12 was formed by omitting the step shown in FIG. 1 described in Example 3 above. As a result, the joint strength was 14Kg/cm ² at 60℃ and
The heat shrinkage rate at 100°C was 0.05%, the heat shrinkage rate after heat cycle was 0.15%, and the flexibility was 0.18Kg, and all other properties except flexibility were inferior to Example 3 above. was. The table below summarizes the above examples and comparative examples.

[Table] As is clear from the results in the table, the optical fiber supporting spacer of the present invention manufactured by the manufacturing method of the present invention is made of hard thermoplastic resin in the uneven portion of the twisted structure of tensile strength wire 1. Since the primary coating layer 3 is closely packed, large bonding strength is obtained, and since the heat distortion temperature of this resin is high, the shrinkage rate is small over a wide range of environmental temperatures.
The bonding strength is stable even with temperature changes. Further, since the spacer main body 9 portion is softer than the primary coating layer 3, the flexibility required when installing and laying the optical fiber in the groove of the main body 9 is also ensured. Furthermore, since the resins forming the spacer body 9 and the primary coating layer 3 have high compatibility, the bonding strength at their interface does not pose a problem, and the coating process is divided into two stages when manufacturing the spacer 12. As a result, residual strain during cooling and solidification can be alleviated. <<Effects of the Invention>> As described above in detail in the Examples, according to the present invention, the bonding strength between the spacer body and the tensile strength wire is high, the dimensional stability against temperature changes is good, and the flexibility is moderate. Excellent effects such as the ability to manufacture an optical fiber supporting spacer with relative ease can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the process of primary coating of the present invention, FIG. 2 is an explanatory diagram showing the process of forming a spacer body, and FIG. 3 is a sectional view showing an example of the optical fiber supporting spacer of the present invention. . DESCRIPTION OF SYMBOLS 1... Tensile strength wire, 3... Primary coating layer, 9... Spacer main body.

Claims (1)

[Scope of Claims] 1 A tensile strength line having a twisted structure, a primary coating layer made of a hard and heat-resistant thermoplastic resin surrounding the tensile strength line, and a phase layer with the thermoplastic resin on the outer periphery of the primary coating layer. and a spacer body formed of a thermoplastic resin that has a high solubility and is softer than the thermoplastic resin, and the primary coating layer includes an uneven portion of the tensile strength wire that has a twisted structure at the interface with the tensile strength wire. The spacer body is closely filled with the primary coating layer, the spacer body and the primary coating layer are fused and bonded, and the spacer body is formed with a plurality of grooves for attaching optical fibers continuously extending in the longitudinal direction. Spacer for supporting optical fiber. 2 The thermoplastic resin of the above primary coating layer is 150Kg/
Claim 1, characterized in that it has a bending modulus of elasticity of mm ² or more, and a thermal deformation temperature of 100° C. or more under a load of 18.6 Kg/cm ² Spacer for supporting optical fiber. 3. A tensile strength wire having a twisted structure is inserted into a crosshead die, and a hard and heat-resistant thermoplastic resin is melted and extruded around the outer periphery of the crosshead die to tightly cover the uneven portions of the tensile strength wire having a twisted structure, and the unevenness of the tensile strength wire having a twisted structure is at least 0.25. After forming a primary coating layer having a coating thickness of mm or more, a plurality of grooves extending in the longitudinal direction are formed on the outer periphery of the primary coating layer using a soft thermoplastic resin that has high compatibility with the thermoplastic resin. 1. A method for manufacturing an optical fiber supporting spacer, comprising forming and covering the spacer.