JPH0481706A - Polyethylene spacer for optical fiber cable - Google Patents

Abstract

PURPOSE:To reduce the surface roughness of this spacer, to improve the productivity, and to stabilize transmission characteristics of the optical fiber by specifying the mean surface roughness of the surface of the polyethylene spacer for the grooved optical fiber cable formed of a specific polyethylene material. CONSTITUTION:The polyethylene spacer 10 is formed of the polyethylene material 2 whose melt index M.I. is >=0.3g/10min so that the mean surface roughness Ra of the surface is <=1.5mum. Thus, while the surface roughness of the spacer main body is held excellent, therefore, while excellent transmission characteristics of the optical fiber cable housing optical fibers 5 is secured, the spacer extrusion molding speed at the time of the manufacture can be increased to, for example, a >=5m/minute high speed. The plastic fast extrusion molding of the spacer 10 for the optical fiber cable is suitably performed and the efficiency of the productivity and the stabilization of the transmission characteristics of the optical fibers are realized.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a polyethylene spacer for optical fiber cables having a helical groove for accommodating an optical fiber on its outer periphery. The present invention relates to a polyethylene spacer for optical fiber cables, which is highly productive with reduced irradiation and stabilizes the transmission characteristics of optical fibers.

[Conventional technology]

FIG. 4 shows an outline of the structure of this type of polyethylene spacer with spiral grooves for optical fiber cables. Central tensile strength member (tension member) to centrally support the cable load
A polyethylene spacer 40 with a spiral groove for an optical fiber cable is formed by extruding polyethylene 42 into a shape having a spiral groove 43 on its outer periphery in one or two layers.

Conventional materials used for profile extrusion molding of this polyethylene spacer include melt index (hereinafter referred to as M, 1.
That's what it means. ) or less than 0.2g/10min polyethylene has been used. In profile extrusion molding having such a complicated cross-sectional shape, M, 1. This is because a material with a low viscosity, that is, a material with a high viscosity when melted, is more advantageous in controlling the shape, and a complex cross-sectional shape can be realized with higher precision.

[Invention or problem to be solved]

In the method of manufacturing this type of polyethylene spacer, as long as it is manufactured at a relatively low drawing speed (hereinafter referred to as the drawing speed), for example, a drawing speed of less than 5 m2/min, the polyethylene spacer can have a very good cross-sectional shape. However, if the linear speed is increased, the following problems arise.

(i) Since the melt viscosity of the polyethylene material is high, the pressure of the press becomes too high.

(h), low M, 1. Melt Fracture (Melt Fra
ture), and the surface condition of the spacer becomes rough.

In particular, (ii) the surface condition of the spacer becomes rough.
This is an important problem for storing optical fibers.

In other words, inside the groove of the spacer, the optical fiber core wire to be housed and the polyethylene forming the spacer are in direct contact with each other, so if the surface condition of the spacer is poor, microbending will occur in the optical fiber, especially if it is long. There is a problem in that an increase in transmission loss occurs on the wavelength side, that is, at a wavelength of λ-1, 55 μm.

An object of the present invention is to solve the conventional problems and provide a polyethylene spacer for optical fiber cables that has high productivity with less roughness on the spacer surface and stabilizes the transmission characteristics of the optical fiber. shall be.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a polyethylene spacer for an optical fiber/cable having a spiral groove on the outer periphery for accommodating an optical fiber, the polyethylene is M, 1.
The average surface roughness of the polyethylene spacer for a helical grooved optical fiber cable formed from the polyethylene material is 1.5 μm or less.

Roughness Ra is expressed by the following formula.

[Effect]

Usually, the surface roughness of this type of spacer is the average surface roughness Ra
(Roughness Average).

χ: Longitudinal distance of the sample (spacer in this case), f(χ)・Function that describes the state of unevenness on the surface of the sample, L: Length to be measured when measuring surface roughness, rl Length to be measured If the value is the average of f(χ) within the interval, then the low M, 1. As the extrusion line speed of a polyethylene material having a . That is, the surface of the extruded polyethylene spacer becomes rough.

M, 1. or 0.05.0.09.0.17.0.42.
Five types of polyethylene materials of 0.82 were extruded at an extrusion line speed v
= Extrusion line drawing at 15m/min, 500m each
Long spacer samples 1 to 5 were experimentally produced. Table 1 and FIG. 2 show the results of measuring the average surface roughness Ra of Samples 1 to 5 that were produced as prototypes.

It is indicated by.

FIG. 3 shows an example of changes in f(χ) with respect to rl. The average surface roughness Ra is also referred to as "centerline average roughness," and its physical meaning is the average distance from the centerline, ie, rl.

Therefore, the average surface of the spacer is shown in Table 1.The phenomenon of melt fracture is a surface roughening phenomenon that occurs at the die outlet when a material with low M and l is extruded at high speed.

FIG. 2 shows the material M, 1. and the surface roughness R after extrusion molding
It shows the relationship between M, 1. is 0.5g/1
In the region lower than 0min, Ra increases rapidly,
Therefore, it is unsuitable for use as a spacer for optical cables.

From the above experimental results, M of polyethylene material, 1. 0,
By selecting 3 g/10 min or more, a polyester spacer stably having a smooth surface with an average surface roughness Ra of 1.5 μm or less was obtained.

Based on the above experimental results, in order to suppress the increase in transmission loss of the optical fiber core due to the surface roughness of the polyethylene spacer, the present invention has been developed to reduce
1. By setting the average surface roughness Ra of the formed polyethylene spacer to 1.5 μm or less and 0.3 g/10 min or more, high productivity and stabilization of the transmission characteristics of the optical fiber can be achieved. Examples will be described below.

〔Example〕

FIG. 1a is a sectional view of an optical fiber cable using the polyethylene spacer for optical fiber cable of the present invention. This example uses a polyethylene spacer IO for an optical fiber cable made of polyethylene 2 and incorporating a central tensile strength member 1 having five spiral grooves on the outer periphery with an outer diameter of approximately 9 mmφ.
This is a prototype of a 100-fiber optical fiber cable in which optical fibers/tape cores 3 are assembled. The twisting pitch of the spiral grooves is 400 mm.

FIG. 1 shows the cross-sectional structure of the optical fiber ribbon 3 housed therein. The optical fiber tape core 3 has a structure in which a single mode optical fiber 5 coated with an ultraviolet curable resin and having a diameter of 250 μm is collectively coated with an ultraviolet curable resin 4 in the form of a four-fiber tape, and has a width W of approximately 1.1 mm and a thickness. D is approximately 0.4 mm.

Regarding the material of the polyethylene 2 of the polyethylene spacer 10, M, 1. = 0.05g/10min,
M.I.

Two types of samples using two types of H-DPE materials of 0.8g7'10min were used.

Using these two types of polyethylene spacers, two types of optical fiber cables each having a length of 500 m and having the structure shown in FIG. 1a were prototyped.

Regarding sample 1 and sample 2 of the optical fiber cables that were prototyped, the melt index M of the polyethylene material of the spacer used was 1. and the average surface roughness Ra of the spacer and the wavelength λ of the 5 optical fiber tapes stored at the bottom of the 5 spiral grooves of the spacer after being made into a cable, that is, a total of 20 optical fibers = 1. The measured values of the transmission loss increase Δα at 55 μm are summarized in Table 2.

Table 2 M of tyrene materials, 1. Since the average surface roughness Ra of the spacer is low and minute irregularities are formed, macrobenzo ink is generated in the optical fiber, and an increase in transmission loss at a wavelength of 1.55 μm is observed.

On the other hand, in sample 2, by selecting sufficiently large M and i of the polyethylene material, the surface of the spacer becomes smooth, the average surface roughness Ra decreases, and the increase in transmission loss at a wavelength of 1.55 μm is suppressed to almost 0. It turns out that it is possible.

In addition, as previously confirmed through experiments and as is clear from the above examples, the polyethylene material of the polyethylene spacer according to the present invention is M, 1. or 0.3 g/10 min (with this, the average surface roughness of the surface of the polyethylene spacer is 1.
By being less than 5μ, the roughness of the spacer surface, especially the surface of the spiral groove that accommodates the optical fiber, can be maintained at a good level, and the extrusion molding speed during manufacturing can be increased while ensuring good transmission characteristics as a surface fiber cable. However, in general, due to the manufacturing equipment, productivity, quality control, etc. of the extrusion process, it is actually difficult to use polyethylene materials! i1.1.
is 1.50g/10 As is clear from Table 2, sample 1
It is preferable that the average surface roughness Ra of the surface of the polyethylene spacer is about 0.3 μm or more.

〔Effect of the invention〕

As described above, the helical grooved polyethylene spacer for optical fiber of the present invention is made of a polyethylene material with a melt index M, . By configuring the spacer to have a Ra of 1.5 μm or less, the surface roughness of the spacer body can be maintained at a good level. Therefore, while ensuring good transmission characteristics as an optical fiber cable that accommodates optical fibers, the spacer body can be The extrusion speed can be increased to a high speed of, for example, 5 m/min or more, making it suitable for high-speed extrusion molding of plastics as spacers for optical fiber cables, and is effective in improving productivity and stabilizing the transmission characteristics of optical fibers. be.

[Brief explanation of drawings]

FIGS. 1a and 1b are block diagrams of an embodiment of the polyethylene spacer for optical fiber cables of the present invention, and FIG. 2 shows the melt index M of the polyethylene material of the polyethylene spacer, 1.
A diagram showing the relationship between and the average surface roughness Ra of the spacer surface,
FIG. 3 is a diagram for explaining the surface roughness of the spacer, and FIG. 4 is a schematic diagram of the configuration of a polyethylene spacer with a spiral groove for an optical fiber cable. ■, 41... Central tensile strength body, 2, 42... Polyethylene, 3... Optical fiber tape core wire, 4... UV curable resin coating, 5... Optical fiber, 10... Light Polyethylene spacer for fiber cable, 40... Polyethylene spacer with spiral groove for optical fiber cable,
43... Spiral groove patent applicant Sumitomo Electric Industries Co., Ltd. Agent Patent attorney Tamamushi Gobe 3 Optical fiber tape core wires M, J, [(1/1 ominl polyethylene material - Melt of polyethylene material INOTENOKUZU 5M , L) and the roughness (Ra
> Which relationship Figure 2 Polyethylene spacer actual P for off-fiber cable 'tb of the present invention! fp1 Dermatology Figure 1 Diagram explaining the surface roughness of the spacer Figure 3

Claims (1)

[Claims] In a polyethylene spacer for an optical fiber cable, the outer periphery of which is provided with a spiral groove for accommodating an optical fiber, the polyethylene has a melt index of 0.3 g/10 m.
A polyethylene spacer for an optical fiber cable, characterized in that the surface of the polyethylene spacer for an optical fiber cable with a spiral groove formed of the polyethylene material has an average surface roughness of 1.5 μm or less.