JPS61170711A - Optical fiber core - Google Patents

Abstract

PURPOSE:To obtain an optical fiber core with which the transmission loss is lessened even after coating of the outermost layer coating and at a low temp. by using a resin curable by UV rays consisting essentially of an urethane acrylate modified silicone oligomer to form the primary coating layer inscribing the outermost layer coating among plural coating layers. CONSTITUTION:The primary coating layer inscribing the outermost layer coating among the plural coating layers of the optical fiber core is constituted of the resin curable by UV rays consisting essentially of the urethane acrylate modified silicone oligomer. The optical fiber core 5 is manufactured by forming first the inside coating layer 2 consisting of the resin curable by UV rays having about 0.1-0.5kg/mm<2> Young's modulus around an optical fiber 1, providing the primary coating layer 3 consisting of the resin curable by UV rays consisting essentially of the urethane acrylate modified silicone oligomer around the layer 2 and forming Nylon 12 which is a thermoplastic resin by extrusion coating as the outermost layer coating 4 on the outside of the layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an improvement in a coated optical fiber formed by applying a plurality of coating layers to an optical fiber.

[Prior art]

Conventionally, for example, as shown in FIG. 3, an inner coating layer 2, a secondary coating layer 3, and an outermost coating layer 4 are applied around an optical fiber 1 having a core and a cladding formed around the core. An optical fiber core 5 coated with a plurality of coating layers is known.

Now, as a typical example of the optical fiber core 50 having the above structure, the inner coating layer 2 is made of thermosetting silicone having a high refractive index, and the secondary coating layer 3 is made of thermosetting silicone having a low refractive index. The outermost coating layer 4 may be made of a thermoplastic resin such as nylon-12, or the inner coating layer 2 may be made of a relatively soft resin, such as having a Young's modulus of 0.
It is composed of an ultraviolet curable resin with a weight of about 05 to 0.5 kg to provide a buffering effect, and also has a Young's modulus of 1 to 50 kg around the inner coating layer 2 in consideration of ease of handling.
There is one in which a primary coating layer 3 made of a relatively hard ultraviolet curable resin such as approximately g/Wt is applied, and finally, as in the former case, a thermoplastic resin such as nylon-12 is coated as the outermost coating 4. .

However, the two types of optical fiber cores 5 have the following problems. First of all, in the case of the former, there is a limit to the curing speed of the thermosetting resin, and the manufacturing line speed has been reduced to 200%.
~300 m/sin L cannot be raised. In addition, in the case of a combination of thermosetting silicone resin and nylon, hydrogen is likely to be generated, and the hydrogen causes an increase in transmission loss in the optical fiber 1 in a specific frequency range.On the other hand, in the case of the latter, the problem with the former is solved. However, when the outermost coating layer 4 is extruded and coated around the primary coating layer 3 made of an ultraviolet curable resin, the heat of the extrusion coating causes the secondary coating layer 3 to be cured by ultraviolet rays, which has relatively high hygroscopicity. Since the optical fiber is made of a synthetic resin, the absorbed moisture evaporates, resulting in poor appearance of the optical fiber core 5, and furthermore, this heat causes thermal deterioration and non-uniform curing of the primary coating layer 3. Specifically, a phenomenon occurs in which the transmission loss of the optical fiber 1 increases. In addition, as is common with many UV-curable resins, their Young's modulus increases rapidly at low temperatures, which causes a large contractile force to act on the inner optical fiber, causing an increase in transmission loss. be.

[Purpose of the invention]

In view of the above problems, an object of the present invention is to provide an optical fiber coated wire in which the second coating layer inscribed in the outermost layer coating is made of an ultraviolet curable resin, so that the appearance of the optical fiber coated wire is good and the second coating layer inscribed in the outermost coating layer is made of an ultraviolet curable resin. Another object of the present invention is to provide a coated optical fiber with little increase in transmission loss even at low temperatures.

[Structure of the Invention] In order to achieve the above-mentioned object, the present invention provides an optical fiber coated wire in which a plurality of coating layers are applied around an optical fiber having a core and a cladding. The primary coating layer inscribed in the outer coating is characterized by being made of an ultraviolet curable resin whose main component is a urethane acrylate modified silicone oligomer.

[Embodiments of the invention]

In order to achieve the above object, the present inventor has provided
As a material, it has low moisture absorption and low water absorption.
Experimental investigations were conducted on various materials from the viewpoint that they must have excellent heat resistance and a small increase in Young's modulus at low temperatures. As a result, it has been found that it is effective to use an ultraviolet curable resin containing a urethane acrylate modified silicone oligomer as the secondary coating layer 3. This will be explained in detail based on an example. FIG. 1 shows an embodiment of the optical fiber core 5 of the present invention.

To explain according to this figure, the present invention first includes an inner coating made of an ultraviolet curable resin having a Young's modulus of approximately 0.1 to 0.5 b/ms around an optical fiber 1 having a core and a cladding. A primary coating layer 3 made of an ultraviolet curable resin whose main component is a urethane acrylate modified silicone oligomer is provided around the inner coating layer 2, and an outermost coating 4 is provided on the outside of the secondary coating layer 3.
It is extrusion coated with nylon-12, which is a thermoplastic resin. In the examples (referred to as actual in the table) and comparative examples (referred to as "improvement" in the table), A is urethane-based ultraviolet curable resin, B is
B is a UV-curable resin containing a urethane acrylate-modified silicone oligomer as a main component, C is a UV-curable resin that does not contain a urethane acrylate-modified silicone oligomer, and D is a mercaptan-containing unsaturated group at both ends instead of the urethane acrylate-modified silicone oligomer. It is an ultraviolet curable resin whose main component is blocking polysiloxane. In addition, the dimensions of the optical fiber core vA5 used in the table are as follows: the outer diameter of the optical fiber 1 is 125118, the outer diameter of the inner coating layer 2 is 250μ, and the outer diameter of the secondary coating layer 3 is 400μ.
μm, and the outer diameter of the outermost coating 4 is 900 μm.

Further, the unit of transmission loss is dB/-. Further, as a method for measuring Young's modulus, a dumbbell-shaped sheet was punched out from a sheet having a thickness of 200 to 250 μm, which had been cured by irradiation with 3.5 J/− of ultraviolet light, and tested in accordance with JIS K7113. Use size 2 dumbbells. Also, the chuck interval is 25
1111, and the distortion was read from the chart.

Calculate. The tensile speed was 1 mm/sin.

As shown in the table above, when the primary coating layer 3 inscribed in the outermost coating 4 is composed of an ultraviolet curable resin whose main component is a urethane acrylate modified silicone oligomer, the outermost coating 4 made of nylon-12 can be extruded and coated. However, since the primary coating layer 3 inside the outermost coating 4 is an ultraviolet curable resin whose main component is a urethane acrylate modified silicone oligomer with low moisture absorption and water absorption, the optical fiber core &I5
There was no deterioration in appearance, and no increase in transmission loss was observed after extrusion coating. In addition, even at −40° C., the transmission loss of the optical fiber 1 did not increase at all. On the other hand, for example, an ultraviolet curable resin whose main component is polysiloxane containing mercaptan and blocked with unsaturated groups at both ends has strong adhesion with the outermost coating 4,
It is estimated that when the outermost coating 4 thermally contracts at low temperatures, the effect is transmitted to the optical fiber 1, resulting in a significant increase in transmission loss. Also, although not shown in the table, room temperature (approx.
For ultraviolet curable resins whose main component is urethane acrylate-modified silicone oligomers and whose Young's modulus exceeds 2 kg/+i+m'' at temperatures around Therefore, when optical fibers were actually coated, the characteristics varied widely and could not be put to practical use.

FIG. 2 shows another embodiment of the present invention, in which the inner coating layer 2 is composed of a plurality of coating layers 2A and 2B, for example, 2A is made of a thermosetting resin and 2B is made of an ultraviolet curable resin. In any case, the inner coating layer 2 inside the next coating layer 3 may be one layer or multiple layers (and whether these layers are composed of a thermosetting resin or an ultraviolet curable resin). The present invention can be applied even if

〔Effect of the invention〕

As described above, in the optical fiber core of the present invention, the primary coating layer inscribed in the outermost coating made of a thermoplastic resin is composed of an ultraviolet curable resin whose main component is a urethane acrylate-modified silicone oligomer. The ultraviolet curable resin whose main component is acrylate-modified silicone oligomer has low moisture absorption, low water absorption, and little increase in Young's modulus at low temperatures, so the outermost coating of the optical fiber core has a good appearance and the outermost layer It has the excellent effect that there is little increase in transmission loss after coating, and there is also little increase in transmission loss even at low temperatures.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing one embodiment of the optical fiber core according to the present invention and another embodiment, and FIG. 3 is a cross-sectional view showing a conventional optical fiber core. 1--Optical fiber 2--Primary coating layer 3--
...-Next coating layer 4---Outermost layer coating 5--
−・Optical fiber core wire

Claims (2)

[Claims] (1) In an optical fiber coated wire formed by applying a plurality of coating layers around an optical fiber having a core and a cladding,
An optical fiber core wire characterized in that a primary coating layer inscribed in the outermost coating among the plurality of coating layers is made of an ultraviolet curable resin whose main component is a urethane acrylate modified silicone oligomer. (2) A patent characterized in that the Young's modulus E of the ultraviolet curable resin whose main component is the urethane acrylate modified silicone oligomer at room temperature is 0.4≦E≦2.0 (kg/mm^2) An optical fiber core according to claim 1.