JPS61179408A - Spacer for carrying optical fiber and its production - Google Patents

Abstract

PURPOSE:To improve the reliability of a spacer by a simple process for production by forming a primary coating layer for enclosing tensile wires of an adhesive thermoplastic resin and a spacer body part of a thermoplastic resin having large compatibility with the adhesive thermplastic resin. CONSTITUTION:While the tensile wires 1 are inserted into the 1st cross head die 3, the molten adhesive thermoplastic resin is supplied to the outside periphery thereof to form the primary coating 4 to 0.1-0.5mm thickness, by which a core strand 5 is obtd. The core strand 5 is inserted into the 2nd cross head die 6 having the shape resembling to the sectional shape of the spacer and the thermoplastic resin having the large compatibility with the adhesive thermoplastic resin is supplied in the molten state to the outside periphery of the layer 4 so that the spacer body 8 formed with the spiral optical fiber contg. grooves having projections 7 on the outside periphery is obtd. The simple process for producing the spacer for carrying the optical fibers which has the large joining strength between the spacer body and the tensile wires, obviates the change with environmental temp. decreases the transmission loss of the optical fibers and has high reliability is thus obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a spacer for supporting an optical fiber as an optical fiber cable element used when forming an optical fiber into a form of an optical fiber cable that can be laid, and a method for manufacturing the same. Regarding.

(Prior art and its problems) This type of spacer uses a monotonic wire, twisted steel wire, etc. as a tensile strength wire, and the outer periphery of the spacer body is coated with a thermoplastic resin. A device with a plurality of continuous spiral grooves is known, and its manufacturing method involves inserting a tensile strength wire into a crosshead die and melting the thermoplastic resin from the die while rotating a die of various shapes. Methods such as extrusion, coating, cooling and solidification are well known.

In such conventional spacers for supporting optical fibers, the tensile strength wire is a monotonic wire or twisted steel wire, and the coating resin for forming the spacer body has various physical properties such as compression resistance, weather resistance, and heat resistance, and resin price. High-density polyethylene (hereinafter referred to as HDP) is generally used because of its balance.

However, the above steel wire and the H coated on its outer periphery
When the tensile strength line is a monotonic line, the bonding force in the longitudinal direction with the spacer body due to DPE is mainly due to HDPE.
This is due to the radial shrinkage force when the resin solidifies, and if the tensile strength wire is a twisted steel wire, in addition to the above bonding force,
A bonding force is obtained based on the unevenness based on the twisted structure of the twisted steel wire and the locking force due to so-called anchor adhesion caused by the thermoplastic resin extruded and coated on the uneven portion. However, the bonding force of the above-mentioned level cannot be said to be sufficient bonding force to withstand various environmental temperature changes, and there are problems as described below.

That is, the linear expansion coefficient of the tensile strength line and the linear expansion coefficient of the spacer body made of the thermoplastic resin are different, and the spacer body with a larger linear expansion coefficient expands and contracts more than the tensile strength line in response to a change in the ring fFjA degree. There was a fear that microbending loss would occur in the optical fiber placed in the groove of the spacer, increasing transmission loss.

(Objective of the Invention) The present invention was made in view of the above-mentioned conventional problems, and its purpose is to minimize changes in environmental temperature, which may cause adverse effects such as increased transmission loss in optical fibers. An object of the present invention is to provide a spacer for supporting an optical fiber that has low resistance and high reliability, and a method for manufacturing the same.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an optical fiber supporting spacer that includes a tensile strength wire made of steel wire or the like, a primary coating layer surrounding the tensile strength wire, and a primary coating layer. a spacer main body in which an optical fiber storage groove extending in the longitudinal direction is formed on the outer periphery of the spacer, and the primary coating layer is formed of an adhesive thermoplastic resin, while the spacer main body is formed of the adhesive thermoplastic resin. The outer periphery of the primary coating layer and the inner periphery of the spacer body are fused and bonded to each other, and the manufacturing method is to attach a tensile strength wire to a crosshead die. While inserting it, supply molten adhesive thermoplastic resin to the outer periphery to extend the length of 0.1 to 0.5 m.
After forming a primary coating layer with a thickness of m, a thermoplastic resin having high compatibility with the adhesive thermoplastic resin is supplied in a molten state to the outer periphery of the first coating layer, and a continuous light beam is applied to the outer periphery in the longitudinal direction. The present invention is characterized in that the spacer body is coated to form a spacer body having a fiber storage groove.

To explain in more detail, the above tensile strength line is optical fiber?
Selected according to the required tensile strength as an element of Iba cable! Li steel wire or twisted steel wire is used, and in the case of monotonous wire, φ0.95 to 2.6 mm, especially φ 1
．． 2-2. On+m types are often used. This is degreased with an organic solvent such as acetone, heated if necessary, and inserted into a crosshead die.

The above-mentioned primary coating layer may include epoxy-modified, carboxylic acid-containing, or maleic acid-modified polyolefin adhesive resins that have adhesive properties with steel wires, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, and various other materials. Polyamide copolymer resins of fatty acids and chlorinated polyolefins are used.

The coating thickness of the primary coating layer to be applied is 0.1 to 0.
Approximately 5 mm is preferable. When the coating thickness is increased, the adhesive resin generally exhibits rubber-like properties, resulting in a decrease in the compression resistance of the spacer.

In addition, in the second coating process, after degreasing the steel wire with a solvent such as acetone, the steel wire is heated to 150 to 200°C, inserted into a crosshead die, and extruded and coated in an annular shape with an adhesive resin. However, if the coating is then cooled and solidified, and if necessary, the outer surface of the coating is shaped by passing it through a shaping die, the outer diameter accuracy can be improved.

In addition, when using a chlorinated polyolefin as a secondary coating, a steel wire is inserted into the liquid chlorinated polyolefin dissolved in a solvent, the liquid chlorinated polyolefin is applied, and the solvent is then dried and removed. Form a primary coating layer.

On the other hand, as the spacer body forming resin, a resin that has a high compatibility with the adhesive resin of the second RFI layer and can be fused and bonded to the primary coating layer, for example, adhesive polyethylene is used for the second coating. In the case of polyethylene resins such as low density PE (LDPE), linear low density PE (LLDPE), high density PE (HDPE), and polyamide resins, -
When using adhesive polypropylene resin for the next coating, use resins with high compatibility with each other, such as polypropylene homopolymer or its copolymer, for the primary coating resin and the spacer body forming resin, such as resins of the same type or type. By doing so, the interface between the two is melted and bonded.

(Function) The outer periphery of the single steel wire or twisted steel wire as the tensile strength wire and the inner periphery of the primary coating layer made of adhesive resin are bonded together by the adhesive force between the two, and the outer periphery of the primary coating layer and the spacer body are bonded together. Since the inner periphery is fused and bonded using resins with high mutual compatibility, the bonding force between the tensile strength wire and the spacer body is strong, and the appearance of the spacer body is The thermal expansion coefficient of the tensile horn wire approximates that of the tensile horn wire.

Therefore, when used as an element of an optical fiber cable, the influence of the thermal behavior of the spacer main body, which inherently has a large coefficient of thermal expansion, due to environmental temperature changes is reduced.

(Example 1) After cleaning the surface of a single steel wire with an outer diameter of 0.95 mm as the tensile strength wire 1 with acetone and degreasing it, it is inserted into a dry heat oven 2 at 180°C, and then the first crosshead It is inserted into the die 3 and coated with adhesive polyethylene (manufactured by Nippon Petrochemicals Co., Ltd., trade name N Polymer A1050), and the outer diameter is 1.
, a 6 mm core strand 5 was obtained.

This core strand 5 is then passed through a second crosshead die 6 having a rotating die corresponding to the cross-sectional shape of the spacer, which will be described later.
high-density polyethylene (
M I = 0.3), the mountain diameter is 7. Omm
, valley diameter 3. After being coated to form a spacer body 8 having 6 protrusions 7 of 0 mm and a spiral pitch of 260 mm, it was introduced into a cooling tank 9 to be cooled and solidified, and then wound onto a drum 10. .

The bonding strength between the spacer main body 8 and the tensile strength wire 1 of the optical fiber supporting spacer manufactured in this way was measured by the following method.

That is, the end portion 10mIIl of the spiral spacer main body 8
Regarding the length, the thermoplastic resin part in the cross-sectional direction of the helical spacer main body 8 was clamped with a jig of the chuck part of a tensile tester, and the tensile shear bonding strength was measured by pulling at a tensile rate of 51IIlZ, and the value was expressed as the tensile force line. The bonding strength (handling strength) was determined by dividing by the area of the outer periphery of the child 11H.

The bonding strength of the spacer of this example according to this measurement method was 4
The amount was 2 kg/c.

In addition, a sample with a length of about 1 m was placed in a dry heat oven at 60°C and 100°C and left for 1 hour, and then left at 23°C (room temperature) for 30 minutes, and then the length of the spacer body 8 was measured. Measure (L
') mm, and the heat shrinkage rate was measured using the following formula.

Heat shrinkage rate = ((1000-L)/1000) x
10o (%) The heat shrinkage rate of the sample of this example was -0.05% at 60°C and 0.08% at 100°C.

Furthermore, when the tensile strength line 1 and the coefficient of thermal expansion of the spacer body 8 were determined in the process of increasing the temperature from 23°C to 60°C, it was found that in the sample of this example, the spacer body 8 was 1.1.
XIO-5/°C and tensile strength line 1 were 1.0 x 10-5/°C, which were very similar values.

(Comparative Example 1) The spacer main body 8 was formed directly on the outer periphery of the tensile strength wire 1 without applying the primary coating 4 of the above-mentioned Example 1, and the other material composition etc. were the same as in Example 1. did.

As a result, the bonding strength was extremely low at 5 kg/cd, and neither the thermal contraction rate nor the thermal expansion rate were satisfactory.

(Example 2) A tensile strength wire 1 is a twisted steel wire with an apparent outer diameter of 1.2 mm, which is made by twisting steel wires with a single wire diameter of 0.38 va into a structure of <3+6).
It was degreased in the same manner as in Example 1, heated, and coated with the same adhesive PE resin as in Example 1 to an outer diameter of 2.0 mm. This was inserted into a crosshead die 6 equipped with the same rotary die as in Example 1, and coated with the same resin as in Example 1 to form the spacer body 8.

The physical properties of the helical spacer according to this example obtained in this way include a bonding strength of 51 kg/c# and a heat shrinkage rate of 60°C.
-0.05 (%) at , 0.05 at 100℃
(%), and the coefficient of thermal expansion is 1x1 for the spacer body.
0'/'C, tensile strength line 1 was 1.0X10-5.

(Comparative Example 2) The spacer main body 8 was formed directly on the outer periphery of the tensile strength wire 1 without applying the primary coating 4 of the above-mentioned Example 2, and the other material composition was the same as that of Example 2. did.

As a result, the bonding strength was not very high at 13 kg/cm, and neither the thermal contraction rate nor the thermal expansion rate were satisfactory.

The table below summarizes the above constituent materials and test results.

(Effects of the Invention) As is clear from the above explanation and table, in the optical fiber supporting spacer according to the present invention, the bonding strength between the spacer body and the tensile strength wire is extremely high, the thermal shrinkage rate is small, and Since the thermal expansion coefficients of the spacer body and the tensile strength wire are similar, it has high dimensional stability against changes in the surrounding environment when actually laying an optical fiber, and reduces the transmission loss of the optical fiber. There will be no need to increase it.

Further, such a highly reliable spacer can be manufactured relatively easily by adding a step of applying a primary coating to the conventional manufacturing method.

Since the spacer body is formed and coated after the second coating is applied, the difference in cooling rate between the protruding part and the inner circumferential part of the spacer body during cooling and solidification is alleviated, and the spiral shape does not collapse. , a well-shaped spacer can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic view showing the steps of the present invention, and FIG. 2 is a sectional view of the spacer body. 1...Tensile strength line 2...Dry heat furnace 3...First crosshead die 4...
......-Next coating 5...Central strand 6...Second crosshead die 7...
...Protrusion 8 ...Spacer body 9 ...Cooling tank 10 ...Drum

Claims (2)

[Claims] (1) A spacer body comprising a tensile strength wire made of steel wire or the like, a primary coating layer surrounding the tensile strength wire, and a spacer main body in which an optical fiber storage groove extending in the longitudinal direction is formed on the outer periphery of the primary coating layer. , the primary coating layer is formed of an adhesive thermoplastic resin, and the spacer body is formed of a thermoplastic resin having high compatibility with the adhesive thermoplastic resin, and the outer periphery of the primary coating layer and the spacer body are formed of a thermoplastic resin having high compatibility with the adhesive thermoplastic resin. A spacer for supporting an optical fiber, characterized in that it is formed by fusing and adhering the inner periphery of the main body. (2) While inserting the tensile strength wire into the crosshead die, molten adhesive thermoplastic resin is supplied to the outer periphery of the crosshead die.
After forming a primary coating layer with a thickness of ~0.5 mm, a thermoplastic resin having high compatibility with the adhesive thermoplastic resin is supplied in a molten state to the outer periphery of the primary coating layer, and is continued in the longitudinal direction around the outer periphery. 1. A method of manufacturing an optical fiber supporting spacer, comprising coating the spacer to form a spacer main body having an optical fiber storage groove.