JP2006323072A - Coated optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated optical fiber excellent in the removal of coating. <P>SOLUTION: In the coated optical fiber 1, a primary coating layer 3 and a secondary coating layer 4 are formed in this order around a glass fiber. The primary coating layer 3 contains fluorine atoms, and the secondary coating layer 4 is formed from a ultraviolet curing resin. The content of the fluorine atoms of the primary coating layer 3 is ≥40 mass% of the entire weight of the primary coating layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical fiber core in which a primary coating layer and a secondary coating layer are laminated around a glass fiber.

As a conventional optical fiber core, a glass fiber around which a glass fiber is coated is generally used. By coating the periphery of the glass fiber with a resin, the glass fiber is prevented from being broken and easy to handle.
As the coating resin used for the optical fiber core wire, an ultraviolet curable resin is known. (For example, refer to Patent Document 1 and Patent Document 2.) Compared to the case of using a thermoplastic resin (for example, nylon, ETFE, etc.) when using an ultraviolet curable resin, an extruder and other incidental equipment can be omitted when manufacturing an optical fiber core wire. It will be excellent.

  Patent document 1 is disclosing the optical fiber core wire which formed the primary coating layer and the secondary coating layer on the glass fiber. A coating material having an elongation of 20 to 50% at a tensile speed of 50 mm / min is used for the secondary coating layer of the optical fiber core wire. According to Patent Document 1, by using such a coating material for the secondary coating layer, the coating layer pieces can be removed in a lump when the coating layer is removed, so that the labor of the operation can be reduced.

Patent Document 2 discloses an optical fiber core wire in which two ultraviolet curable coating layers are applied on a glass fiber having an outer diameter of 125 μm. In this optical fiber core, the Young's modulus of the inner ultraviolet curable coating layer is about 750 to 850 MPa, and the Young's modulus of the outer ultraviolet curable resin layer is 30 to 100 MPa. According to the optical fiber core wire of Patent Document 2, it can be easily removed even with a non-heating type remover.
Japanese Patent Laid-Open No. 11-21944 JP 2003-241033 A

  By the way, when the optical fiber core wire provided with a plurality of resin layers is wired as in the above-mentioned patent document, there is a case where only the outermost layer is peeled and removed and connected to another optical fiber core wire. . In this operation, the ability to easily remove only the outermost layer without peeling off the resin layer immediately below the outermost layer (hereinafter, this performance is referred to as “coating removal property”) is important.

  Further, depending on the optical fiber core wire, a colored layer for discriminating the type or the like may be provided below the outermost layer. In an optical fiber having such a colored layer, if the colored layer is also peeled off at the same time when the outermost layer is removed, the type of the optical fiber cannot be determined, and therefore, the coating removal property becomes even more important.

However, when the resin layer is entirely made of an ultraviolet curable resin for reducing the manufacturing cost, there is a problem that the outermost layer and its lower layer are in close contact with each other and the coating removability is lowered. In Patent Documents 1 and 2 described above, the adhesion between the outermost layer and the lower layer is lowered to improve the coating removal, but further improvement in the coating removal is desired.
The objective of this invention is providing the optical fiber core wire excellent in the coating removal property.

The present inventors have completed the present invention by paying attention to the resin constituting the primary coating layer in the optical fiber core wire in which the primary coating layer and the secondary coating layer are provided on the glass fiber.
That is, in order to achieve the above-described object, the optical fiber core according to the present invention is an optical fiber core in which a primary coating layer containing a fluorine atom and a secondary coating layer are sequentially laminated around a glass fiber. The secondary coating layer is made of an ultraviolet curable resin, and the fluorine content in the primary coating layer is 40% by mass or more based on the total weight of the primary coating layer.

  In the optical fiber core according to the present invention, the primary coating layer is preferably formed of a fluorinated acrylate resin.

  In the optical fiber core according to the present invention, the Young's modulus of the primary coating layer is preferably 10 MPa or more.

  Furthermore, in the optical fiber core according to the present invention, it is preferable that the secondary coating layer is an outermost layer.

  According to the optical fiber core of the present invention, since the primary coating layer contains fluorine atoms, the lubricity of the surface of the primary coating layer is improved, so that the secondary coating layer outside the primary coating layer can be easily removed. it can. Therefore, it is possible to provide an optical fiber core wire excellent in coating removal.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an optical fiber core wire according to an embodiment of the present invention. As shown in FIG. 1, the optical fiber core wire 1 has a glass fiber 2 in the center, and a primary coating layer 3 is formed around the glass fiber 2. A secondary coating layer 4 is provided around the primary coating layer 3.

  The primary coating layer 3 contains fluorine atoms. When the primary coating layer 3 contains fluorine atoms, the lubricity of the surface of the primary coating layer can be improved, and the primary coating layer 3 and the secondary coating layer 4 are made of a resin that is easily adhered to each other. However, it is possible to easily remove only the secondary coating layer 4 while leaving the primary coating layer 3.

The content of fluorine atoms in the primary coating layer 3 is preferably 40% by mass or more, and more preferably 50% by mass or more of the total weight of the primary coating layer 3. When the fluorine atom content is 40% by mass or more, the secondary coating layer 4 can be easily removed at the time of the coating removal operation. Since the adhesion with the secondary coating layer 4 increases, the secondary coating layer 4 may be difficult to remove.
In addition, the fluorine content in the primary coating layer 3 can be measured using ion chromatography.

  In order to make the primary coating layer 3 contain fluorine atoms, (i) the primary coating layer 3 is formed of a resin made of an organic polymer in which the fluorine atoms form a part of the composition, (ii) a fluorine compound (for example, fluorine Examples of such a method include adding sodium chloride and the like to the resin forming the primary coating layer 3, and it is preferable to form the primary coating layer 3 by means of (i) which is excellent in stability during storage.

When the means (i) is used, the resin containing a fluorine atom can constitute a highly reactive resin composition as a main component of an ultraviolet curable resin that can be coated at high speed. Reacts with acrylates (2- (perfluorooctyl) ethyl acrylate, 2,2,3,3-tetraafluoropropyl acrylate, etc.) or methacrylate components (pentafluorobenzyl methacrylate, perfluoronorbornyl methyl methacrylate, etc.) It is preferable to use a fluorinated acrylate resin contained as a reactive monomer or reactive oligomer. As such an acrylate containing a fluorinated alkyl group, a commercially available product can be used. For example, 2-perfluorodecylethyl acrylate, R-2020 (Daikin Chemicals Sales Co., Ltd.) can be used. As other components, the fluorinated acrylate resin has a multifunctional cross-linking agent component (trimethylolpropane triacrylate, diacrylate, pentaerythritol trimethacrylate, which has a plurality of double bonds for adjusting the modulus of elasticity and the viscosity of the resin. Etc.), and an initiator (benzophenone, acetophenone, hydroxycyclohexyl phenyl ketone) that generates radicals by about 1 to 5% by weight of ultraviolet rays to start curing the resin.
When the primary coating layer 3 is formed by the means (ii), the resin constituting the primary coating layer 3 is preferably an acrylic resin, and examples thereof include a urethane acrylate resin and an epoxy acrylate resin. A commercial item can be used as acrylic resin which can be used for the primary coating layer 3, for example, Desolite 950-101 (DSM company) etc. can be used.

  The Young's modulus of the primary coating layer 3 is preferably 10 MPa or more. When the Young's modulus of the primary coating layer 3 is smaller than 10 MPa, problems such as stickiness of the surface of the optical fiber core wire, a decrease in rigidity, and destruction of the primary coating layer 3 due to a slight external pressure may occur. For example, when the optical fiber core wire is handled in the closure, the primary coating layer 3 may be peeled off even if it is rubbed against a plastic edge or the like with a force of about 300 gf.

  The upper limit of the Young's modulus of the primary coating layer 3 is preferably 500 MPa. The upper limit of the Young's modulus of the primary coating layer 3 is 500 MPa, so that when the optical fiber is bent, the deterioration of transmission characteristics caused by the side pressure from the primary coating layer is suppressed, and the strength is such that it does not break when only the outermost layer is removed. Can be imparted to the primary coating layer.

  The secondary coating layer 4 is preferably formed from an ultraviolet curable resin. In particular, as an ultraviolet curable resin for forming the secondary coating layer 4, an acrylate compounded in the secondary coating layer by using a resin containing an acrylate (including methacrylate) component such as a urethane acrylate resin or an epoxy acrylate resin. Because the system component has a high affinity with the acrylate component of the primary coating layer, the resin component is not repelled by the fluorine component of the primary coating layer, and the outer diameter variation of the secondary coating layer, surface irregularities, etc. are less likely to occur. . A commercially available product can be used as the ultraviolet curable resin used for the secondary coating layer 4, and for example, Desolite 950-101 (DSM) or the like can be used.

  The Young's modulus of the ultraviolet curable resin constituting the secondary coating layer 4 is preferably in the range of 700 to 1300 MPa. If the Young's modulus of the ultraviolet curable resin of the secondary coating layer 4 is less than 700 MPa, the rigidity may be insufficient and the protective function of the glass fiber 2 may be insufficient. On the other hand, when the Young's modulus exceeds 1300 MPa, although the protection function of the fiber is improved, it becomes difficult to play a role as a cushioning material, and the glass fiber is likely to be affected by the side pressure due to external force, so that the optical transmission characteristics are deteriorated. There is.

  In the optical fiber core 1, the outer diameter of the glass fiber 2 is about 80 to 400 μm. The thickness of the primary coating layer 3 can be set within a range of 10 to 160 μm, and the thickness of the secondary coating layer 4 can be set within a range of 50 to 900 μm.

The manufacturing method of this optical fiber core wire 1 is demonstrated using FIG. FIG. 2 shows an example of a manufacturing apparatus for manufacturing the optical fiber core wire 1.
As shown in FIG. 2, the manufacturing apparatus 11 for the optical fiber core wire 1 includes a heating furnace 13 for heating and melting the optical fiber preform 12, and below the heating furnace 13 is along a path through which the glass fiber 1 passes. A primary coating die 15, a curing furnace 16, a secondary coating die 17, a curing furnace 18, a capstan 19 and a take-up reel 20 are provided.

  In order to manufacture the optical fiber core wire 1 using the manufacturing apparatus 11, first, the primary coating layer 3 and the secondary coating layer 4 are formed on the primary coating layer die 15 and the secondary coating layer die 17, respectively. A resin composition containing a resin to be used and, if necessary, an additive or the like is filled. By passing the glass fiber 2 melt-spun in the heating furnace 13 through the primary coating layer die 15 and the secondary coating layer die 17, the resin composition is coated around the glass fiber 2. Then, the optical fiber core wire 1 in which the primary coating layer 3 and the secondary coating layer 4 are sequentially laminated around the glass fiber 2 by curing the resin composition by irradiating ultraviolet rays in the curing furnaces 16 and 18. Form.

  As described above, according to the optical fiber core wire 1 according to the present embodiment, the content of fluorine atoms in the primary coating layer 3 is set to 40% by mass or more based on the total weight of the primary coating layer. The lubricity of the surface of the coating layer can be improved, and the coating removal of the secondary coating layer 4 can be easily performed. Therefore, the workability of the coating removal is excellent when wiring the optical fiber core wire.

The optical fiber core according to the present invention may be in the form of a colored layer for discriminating the type or the like by adding a colorant to the primary coating layer. FIG. 3 shows an embodiment of an optical fiber core wire in which the primary coating layer also functions as a colored layer.
As shown in FIG. 3, the optical fiber core 31 is formed with two resin layers (a primary layer 35 and a secondary layer 36) around the glass fiber 2. A colored primary coating layer 3 is formed around the secondary layer 36, and a secondary coating layer 4 is provided around the primary coating layer 3.

The thickness of the primary coating layer 3 is about 5 μm, the thickness of the secondary coating layer 4 is about 320 μm, and the diameter of the optical fiber core wire 31 is about 900 μm. Such an optical fiber core wire 31 is mainly used for indoor wiring.
Also in the optical fiber core wire 31, since the primary coating layer 3 contains fluorine atoms, the secondary coating layer 4 can be easily removed without peeling off the primary coating layer 3. Excellent workability.

  In addition, materials, shapes, dimensions, forms, and the like of the glass fiber 2, the primary coating layer 3, the secondary coating layer 4 and the like exemplified in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved. .

EXAMPLES Although this invention is demonstrated further in detail using an Example, this invention is not limited to a following example.
Example 1
The primary coating layer 3 is formed on the glass fiber 2 having an outer diameter of 125 μm so as to have an outer diameter of 200 μm, and then the secondary coating layer 4 is formed so as to have an outer diameter of 250 μm. Line 1 was formed. As primary coating layer 3, R-2020 (Daikin Chemicals Sales Co., Ltd.) as a main component is added to 80% by weight, and Desolite 950-200 (DSM) containing a crosslinking agent and an initiator is added to 20% by weight. The fluorinated acrylate resin thus prepared was used. The fluorine content of this fluorinated acrylate resin was about 51% by weight because the fluorine content of R-2020 was about 65% by weight. Moreover, the resin of the secondary coating layer 4 used urethane acrylate-type resin (Desolite 950-101 (DSM company)).

  When the Young's modulus of the resin used for the primary coating layer and the secondary coating layer was measured according to the method of JIS K7113, the Young's modulus of the resin of the primary coating layer 3 was 32 MPa, and the Young's modulus of the resin of the secondary coating layer 3 was Was 710 MPa.

(Comparative Example 1)
The resin of the primary coating layer 3 is a fluorinated acrylate having a fluorine content of 32% by mass, by changing the blending ratio of the resin composition of Example 1 to 50% by weight of R-2020 and 50% by weight of Desolite 950-200. An optical fiber core was produced under the same conditions as in Example 1 except that the resin was changed. Table 1 shows the Young's modulus of the resin constituting the primary coating layer and the secondary coating layer of the optical fiber core wire of Comparative Example 1.

(Example 2)
The same conditions as in Example 1 except that the resin of the primary coating layer 3 was changed to a resin having a fluorine content of 50 mass% by mixing 75 wt% NaBF ₄ and 25 wt% desolite 950-200. An optical fiber core wire was manufactured. Table 1 shows the Young's modulus of the resin constituting the primary coating layer and the secondary coating layer of the optical fiber core wire of Example 2.

(Comparative Example 2)
An optical fiber core was produced under the same conditions as in Example 1 except that the resin of the primary coating layer 3 was changed to Desolite 950-200 (DSM) containing no fluorine. Table 1 shows the Young's modulus of the resin constituting the primary coating layer and the secondary coating layer of the optical fiber core wire of Comparative Example 1.

The following coating removal test was conducted on the optical fiber cores of Examples 1 and 2 and Comparative Examples 1 and 2 described above, and the ease of removal of the coating of the optical fiber cores was evaluated.
[Coating removal test]
Similar to nippers used for copper wire coating removal, using a coating removal tool having a hole with an inner diameter of 220 μm divided into both blades at the center axis, and positioned 20 mm from the end of the optical fiber with the other end fixed With this tool, the outer peripheral side of the secondary coating layer is cut, and the tool is moved in the longitudinal direction of the optical fiber, so that a force is applied to the secondary coating layer on the outer periphery of the hole to cut the entire secondary coating layer. An experiment was conducted to remove the secondary coating layer while leaving the primary coating layer adhered to the optical fiber body side. At this time, a strain gauge was attached to the tool, and the maximum stress (pulling force) generated when the secondary coating layer was removed was measured.
The evaluation criteria were as follows.
A: Pulling force is 50 g or less and the primary coating layer is not broken. ○: Pulling force is more than 50 g and 100 g or less, and the primary coating layer is not broken. Δ: Pulling force is 100 g or more. What caused layer destruction

  From the above results, it can be seen that the optical fiber cores (Examples 1 and 2) of the present invention are superior in the coating removal performance as compared with the comparative example.

It is a cross-sectional schematic diagram which shows the optical fiber core wire which concerns on embodiment of this invention. It is a schematic diagram which shows an example of the manufacturing method of the optical fiber core wire which concerns on embodiment of this invention. It is a schematic diagram which shows an example of the manufacturing method of the optical fiber core wire which concerns on embodiment of this invention.

Explanation of symbols

1 Optical fiber core wire 2 Glass fiber 3 Primary coating layer 4 Secondary coating layer

Claims (4)

An optical fiber core in which a primary coating layer containing a fluorine atom and a secondary coating layer are sequentially laminated around a glass fiber,
The secondary coating layer is formed from an ultraviolet curable resin,
The content of fluorine atoms in the primary coating layer is 40% by mass or more based on the total weight of the primary coating layer.   The optical fiber core wire according to claim 1, wherein the primary coating layer is made of a fluorinated acrylate resin.   3. The optical fiber core wire according to claim 1, wherein a Young's modulus of the primary coating layer is 10 MPa or more. The optical fiber core wire according to any one of claims 1 to 3, wherein the secondary coating layer is an outermost layer.

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