JP2001108874A - Coated optical fiber - Google Patents

Abstract

(57) Abstract: The present invention provides a coating in which the occurrence of peeling at the interface between a glass fiber and a primary layer on a line during drawing or rewinding is reduced (that is, peeling resistance is improved). Using an optical fiber and a coated optical fiber with improved peeling resistance,
In addition, the provision of an optical fiber ribbon that can easily remove the coating at a time. A coated optical fiber according to the present invention has a primary layer made of a resin having a relatively low Young's modulus formed on the outer periphery of a glass optical fiber, and a secondary layer made of a resin having a higher Young's modulus than the primary layer is formed on the outer periphery of the primary layer. At least, the primary layer has a Young's modulus of 0.1 MPa or less, and the ratio of the secondary layer to the primary layer has a Young's modulus of 10,000 or more. The adhesion between the primary layer and the glass optical fiber is 5-1.
00 g / cm. The optical fiber ribbon comprising the coated optical fiber of the present invention can be easily removed at once.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated optical fiber.

[0002]

2. Description of the Related Art An optical fiber is obtained by drawing a preform for an optical fiber having at least a core and a clad. The outer periphery of a glass optical fiber immediately after drawing is provided with protective reinforcement, flexibility, and light leakage prevention. The coating is applied for the purpose such as. As this coating, at least a relatively soft (small Young's modulus) primary layer having a buffering action in contact with the outer circumference of the glass optical fiber and a hard (high Young's modulus) secondary layer having a protective action on the outermost circumference are provided. It is known to provide two layers of coating. In some cases, a coloring layer (also referred to as an ink layer) is provided as the outermost coating layer to improve discrimination.

[0003] For example, a pressure of 0.1 MPa
It has a first outer layer made of synthetic rubber having an elastic modulus of 10 MPa and a second outer layer made of a synthetic resin having an elastic modulus larger than that of the first outer layer. The thickness of the first outer layer is 5 to 20 μm and the second outer layer. A coated optical fiber has been proposed in which the elastic modulus of the skin layer is 1000 MPa or more, which is less susceptible to mechanical influence in the lateral direction, and in which deterioration in transmission characteristics due to microbending and temperature is reduced (Japanese Patent Laid-Open No. 1-30111). ).

Further, a first polymer coating layer (primary layer) having a Young's modulus of 1.0 MPa to 3.0 MPa and a glass transition point of 10 ° C. or less, and 400 MPa or more adjacent to the first coating layer. A coated optical fiber has been proposed in which a second polymer coating (secondary layer) having the following Young's modulus is coated to maintain the strength of the fiber and protect the waveguide from the influence of external force (Japanese Patent Laid-Open No. Hei 8-24882).
50).

[0005]

Even in the case of the coated fiber described in the above document, when a small foreign matter is present on the optical fiber at the time of drawing or rewinding the optical fiber, an external force is locally applied. In some cases, separation occurred at the interface between the glass and the primary layer. A first object of the present invention is to provide a coated optical fiber having improved peeling resistance during drawing and rewinding. On the other hand, a plurality of coated optical fibers are arranged in parallel, and a coating layer (common coating layer) is formed on the outer periphery so as to collectively form them to form a tape-shaped core wire. In the case of the connection of the optical fiber tape, it is necessary to peel all the layers below the outermost coating layer of the coated optical fiber together with the common coating layer from the optical fiber surface, and this operation is called collective coating removal, At this time, it is not preferable that the primary layer and the secondary layer remain on the glass surface. The second object of the present invention is to use the optical fiber tape core material as a constituent material without deteriorating the collective coating removal property of the optical fiber tape core and improving the peeling resistance at the time of drawing or rewinding. To provide a coated optical fiber.

[0006]

According to the coated optical fiber of the present invention, which solves the above-mentioned problems, a primary layer made of a resin having a relatively low Young's modulus is formed on the outer periphery of a glass optical fiber, and the primary layer is formed on the outer periphery of the primary layer. In a coated optical fiber obtained by coating at least a secondary layer made of a resin having a higher Young's modulus than the primary layer, the Young's modulus of the primary layer is 0.1 MPa or less, and the ratio of the Young's modulus of the secondary layer and the primary layer is It is not less than 10,000. In the coated optical fiber of the present invention, the adhesion between the primary layer and the silica glass optical fiber is particularly preferably 5 to 100 g / cm. In the present invention, “resin or resin composition” is simply referred to as “resin”.

[0007]

FIG. 1 is a schematic sectional view showing a specific example of a coated optical fiber according to the present invention. The optical fiber 1 has at least a core and a clad, and the Young's modulus provided on the outer periphery of the optical fiber 1 is as follows. A coated optical fiber 4 is formed from a primary layer 2 having a pressure of 0.1 MPa or less and a secondary layer 3 having a large Young's modulus provided on the outer periphery of the primary layer 2. The Young's modulus of the secondary layer 3 is S, and the Young's modulus of the primary layer 2 is S. Is P, S / P ≧ 10000.

FIG. 2 shows a fiber tape core formed by arranging a plurality of coated optical fibers 6 in which a colored layer 5 is further coated on the coated optical fiber 4 of the present invention shown in FIG. FIG. 4 is a schematic cross-sectional view illustrating a specific example of a line 8.

In the present invention, the separation resistance can be improved by setting the Young's modulus of the primary layer of the coated optical fiber and the Young's modulus ratio of the primary layer and the secondary layer to specific values. That is, as the secondary layer becomes harder (the S becomes larger), the external force is less likely to be transmitted to the primary layer, and does not cause separation between the glass / primary layer. On the other hand, even if the secondary layer is softened to some extent, if the primary layer is correspondingly very soft, it does not cause separation, for example, by absorbing external force. Therefore, by setting the ratio of the Young's modulus to the range of the present invention, the peeling resistance is improved.

[0010] Each limitation basis of the present invention will be described. The primary layer of the present invention has a Young's modulus of 0.1 MPa or less, and if it is within this value range and the ratio S / P to the secondary layer's Young's modulus is 10,000 or more, peeling can be prevented and the tape core and In this case, the collective coating removal property can be improved. Primary layer Young's modulus is 0.01PMa
If it is less than 0.1 MPa, the peeling resistance may worsen. On the other hand, if it exceeds 0.1 MPa, the Young's modulus of the secondary layer becomes excessively large because the S / P needs to be 10,000 or more, which is inconvenient.

The Young's modulus of the secondary layer of the present invention is set so as to satisfy S / P ≧ 10000 as described above, preferably S / P ≧ 12000, particularly preferably S / P of 15
000 to 40,000. If the S / P is less than 10,000, the frequency of occurrence of peeling increases.

Further, by increasing the adhesion between the glass and the primary layer (the definition will be described later), it is possible to prevent peeling at the interface between the two. However, if the adhesion is excessively large, it is difficult to remove the sheath at once when the optical fiber ribbon is connected to another optical fiber.
g / cm, particularly preferably 1 g / cm.
0 to 100 g / cm.

In the present invention, the composition, structure, and manufacturing method of the optical fiber (glass fiber) itself are not particularly limited, and follow a known method in this technical field. The use of a silica glass fiber as the glass fiber is advantageous in that the transmission characteristics are excellent.

Examples of the coating material for the primary layer, the secondary layer, etc. of the present invention include, but are not limited to, urethane acrylate, epoxy acrylate, silicon acrylate, fluoride acrylate resins and their resin compositions. It is not something to be done. In the present invention, the resin and the resin composition are collectively referred to as “resin”. Various additives such as reactive monomers, oligomers, polymerization initiators, reaction modifiers, silane coupling agents, leveling agents, coloring agents, antioxidants, flexibility-imparting agents, and adhesives may be added to the resin used as the coating material. , A viscosity adjusting solvent, and the like.

The selection of the coating material for the primary layer and the secondary layer used in the present invention needs to be selected so that the Young's modulus of both satisfies the range of the present invention. Means for this include changing the molecular weight of the polyol portion of the oligomer, changing the number of functional groups of the monomer, and the like, but are not limited thereto.

The means for forming a coating layer such as a primary layer and a secondary layer to be coated immediately after drawing an optical fiber is not limited, and any known method in this technical field may be used. For example, in the case of an energy ray-curable resin such as heat or light, a corresponding energy ray is irradiated to cure the coating material to form a coating layer. The use of an ultraviolet curable resin has the advantages that the coating formation time is short and that high linear speed production is possible.

The coated fiber of the present invention can be formed into a colored core by forming the outermost layer as a colored layer,
Furthermore, when a common core layer is provided to form a tape core wire, the collective covering property is improved, so that it can be suitably used.
As a material for collectively covering the tape core wire, for example, a urethane acrylate-based resin, an epoxy acrylate-based resin, a silicon acrylate-based resin, and the like can be given as in the case of the fly-mary layer and the secondary layer. The use of an energy-ray-curable resin such as heat or light, for example, an ultraviolet-curable resin, is advantageous because the coating formation time is short.

[0018]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

(Example 1) A primary layer is formed on the outer periphery of a silica glass optical fiber having an outer diameter of 125 μm by an outer diameter of 190 to 20.
0 μm, outside diameter of secondary layer 240-250
The coated optical fiber was manufactured to have a thickness of μm.
By changing the composition of the ultraviolet-curable urethane acrylate resin as the primary layer material and the ultraviolet-curable urethane acrylate resin as the secondary layer material (hereinafter referred to as “primary resin” and “secondary resin”, respectively), After obtaining a coated optical fiber having a coating layer with a Young's modulus, each test of a peeling resistance test, a coating physical property evaluation test, and an adhesion measurement was performed and evaluated.

The primary resin used in the present example was a monomer, an oligomer, a silane coupling agent, a photoinitiator,
A urethane acrylate resin composed of an antioxidant or the like. Young's modulus can be reduced by (a) increasing the molecular weight of the polyol portion of the oligomer and (b) reducing the crosslink density. The Young's modulus of the secondary resin was adjusted by the same means as in the case of the primary resin.

Peeling resistance test: Using a fiber rewinding machine (manufacturer, model name), a cap stampy (240
mandrel (0.2 mmφ) perpendicular to the running direction
mmφ) was set and passed therethrough, forcibly causing peeling at the glass / primary layer coating interface, and the occurrence frequency was observed using a microscope. The test conditions were as follows: fiber passage speed: 1.0 m / sec, capstan load tension: 500 g, number of observations: n (locations / condition): 16, peeling frequency (%): (number of peelings / 16 × 10
0).

Coating property evaluation test: The primary layer is Push-
The in-modulus method (43rd IWCS (1994) 552) was used to directly evaluate the Young's modulus of the optical fiber primary layer. Specifically, the coated fiber to be tested is bundled and held in an acrylic pipe, and the gap between the pipe and each coated fiber is filled with epoxy resin and hardened, and sliced with a cutter,
A disk-shaped sample having a constant thickness is prepared, and a glass part is pressed with an indenter using a microhardness meter, and the Young's modulus of the primary resin is calculated from the displacement of the glass. The secondary resin is dipped in an acetone-ethanol solvent, the coating is swollen, the pipe-shaped coating is collected from the glass, and after drying, the marked line 25 mm,
Evaluation was performed at a pulling speed of 1 mm / min.

The following procedure was used to measure the adhesion between the glass and the primary resin. A quartz glass plate (specify the size) was immersed in sulfuric acid for 5 minutes or more to clean the surface. A resin (composition) liquid for forming a primary layer was applied onto the washed quartz glass plate, and cured at an irradiation light amount of 100 mJ / cm ² . The resin layer thickness after curing is 200μm, width is 50mm,
A sample about 150 mm long was obtained. The obtained sample was left for 1 week in a 25 ° C., 50% RH atmosphere. Next, the resin layer of the sample was peeled off from the quartz glass plate by 50 mm in a direction of 180 degrees at a tensile speed of 200 mm / min,
The maximum value of the force (g / cm per unit width) required at this time was defined as the adhesion between the glass and the primary resin.

The adhesion between the glass and the primary layer was adjusted by changing the mixing ratio of a polar monomer contained in the primary resin, for example, acrylamide, N-vinylpyrrolidone, acryloylmorpholine and the like. Also,
The adjustment was also made by changing the blending amount (including 0) of the silane coupling agent in the primary resin.

Tables 1 to 3 show the ratio (S / S) of the Young's modulus of each resin and the Young's modulus of the secondary layer to the primary layer.
P) shows the correlation with the frequency of occurrence of peeling. From this result, it is understood that the ratio of the Young's modulus of each resin is an important factor for the peel resistance. That is, if the S / P is 10,000 or more, improvement in peel resistance can be expected. In addition, a trial production of an optical fiber ribbon having the configuration shown in FIG. 2 and examination of collective covering properties revealed that the adhesion between the glass and the primary layer was 5 g / cm and 10 g / c.
In the case of m and 100 g / cm, all of those in the range of the present invention had good collective coating removal properties. When the adhesion between the glass and the primary layer was 120 g / cm, the collective coating removal property was poor.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

As described above, according to the present invention, the peeling resistance of the coated optical fiber is improved, and the problem of coating peeling on the line at the time of drawing or rewinding can be solved. Also,
The optical fiber ribbon using the coated optical fiber of the present invention has improved collective coating removal properties, and can increase the work efficiency in optical fiber connection and the like.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating a specific example of a coated optical fiber of the present invention.

FIG. 2 is a schematic sectional view showing the structure of an optical fiber ribbon using the coated optical fiber of the present invention shown in FIG.

[Explanation of symbols]

Reference Signs List 1 optical fiber, 2 primary layer, 3 secondary layer, 4 coated optical fiber, 5 colored layer, 6
Coated optical fiber, 7 Common coating layer, 8 Optical fiber ribbon.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H001 BB15 BB22 KK17 2H050 BB04Q BB04S BB07Q BB07S BB08Q BB08S BB14Q BB14S BB17Q BB17S BB31Q BB31S BB33Q BB33S BC03 BD02

Claims (3)

[Claims] 1. A primary layer made of a resin having a relatively low Young's modulus is formed on the outer periphery of a glass optical fiber, and at least a secondary layer made of a resin having a higher Young's modulus is coated on the outer periphery of the primary layer. In the coated optical fiber, the primary layer has a Young's modulus of 0.1
A coated optical fiber having a MPa or less and a ratio of the Young's modulus of the secondary layer to the primary layer of 10,000 or more. 2. A coated optical fiber, wherein the adhesion between the primary layer and the glass optical fiber is 5 to 100 g / cm. 3. An optical fiber ribbon, wherein a plurality of the coated optical fibers according to claim 1 or 2 are arranged in parallel and their outer circumferences are collectively coated with a common resin.