JP2000292661A - Coated optical fiber - Google Patents

Abstract

(57) [Problem] To provide a coated optical fiber having excellent adhesion (peeling resistance) and coating removal properties. SOLUTION: The coated optical fiber 4 in which a primary resin coating layer 2 is provided on the outer periphery of a glass fiber 1, wherein a resin material of the primary resin coating layer 2 has an adhesion force with the glass fiber 1 of 3%.
0 g / cm or more and 80 g / cm or less,
Stress at 100% elongation of 0.04 kg / mm ² or more and 0.25 kg / mm ² or less.

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 mainly used for an optical fiber ribbon, and more particularly to a coated structure having excellent adhesion and coating removal properties.

[0002]

2. Description of the Related Art Conventionally, optical fiber ribbons have been widely used for the purpose of increasing the density of optical fibers housed in optical cables and improving the efficiency of connection work of optical cables. FIG. 5 is a diagram showing a conventional optical fiber ribbon, in which a plurality of coated optical fibers 21 are arranged in parallel, and a collective coating layer 22 made of an ultraviolet curable resin is provided on the outer periphery thereof. Formed. The coated optical fiber 21 is provided with a coating layer 20 made of a soft UV-curable resin on the outer periphery of an optical fiber (hereinafter, abbreviated as “glass fiber”) 1 made of quartz glass.

In such an optical fiber ribbon 23, when the adhesive force between the glass fiber 1 and the coating layer 20 is small, the interface between the glass fiber 1 and the coating layer 20 is partially separated, and Glass fiber 1 at times
Suffers from microbending, the transmission loss of the optical fiber is likely to increase. On the other hand, if the adhesive force between the glass fiber 1 and the coating layer 20 is too large, when the above-mentioned optical fiber ribbon 23 is connected to another optical fiber, the collective coating layer 22
It is difficult to remove the coating layer 20 and expose the glass fiber 1.

[0004] One example of the prior art relating to these problems is:
It is described in JP-A-9-5587. FIG. 5 in which a coating layer 20 is provided on the outer peripheral surface of a glass fiber 1
In the coated optical fiber 21 having the structure shown in FIG.
0 glass fiber 1 and protective layer 20
It describes the relationship of strippability when removing.

[0005]

However, according to various studies conducted by the present inventors, it has been found that, in the coated optical fiber 21 described in Japanese Patent Application Laid-Open No. 9-5587, the distance between the glass fiber 1 and the coating layer 20 is reduced. Even if the adhesion of the glass fiber 1 is adjusted to a predetermined value, the glass fiber 1
In some cases, peeling occurred partially between the coating layer 20 and the coating layer 20, or the coating layer 20 was broken. As a result, transmission loss may increase, and stable characteristics cannot be obtained, and improvement has been desired.

The inventors of the present invention have conducted intensive studies, and as a result, have found a coating structure having excellent adhesion and coating removability, and provide a coated optical fiber using the same. Things.

[0007]

The coated optical fiber according to the present invention is a coated optical fiber having a primary resin coating layer provided on the outer periphery of a glass fiber, wherein the resin material of the primary resin coating layer is in close contact with the glass fiber. The force is 30 g / cm or more and 80 g / cm or less, and the stress at 100% elongation is 0.04 kg / mm ² or more and 0.25 k
g / mm ² or less.

[0008] According to the coated optical fiber of the present invention, the resin material of the primary resin coating layer has an adhesion to the glass fiber of 30.
If it is less than g / cm, the glass fiber cannot be held securely, and interface delamination may occur between the glass fiber and the primary resin coating layer. It becomes difficult to completely remove the resin from the glass fiber, and the coating resin remains.

Further, according to the results of the study by the present inventors,
When a primary resin coating layer is provided on a glass fiber and is wound up through a roller, minute foreign substances on the roller surface come into contact with the primary resin coating layer, and a large portion of the primary resin coating layer comes into contact with the fine foreign substances. It has been found that stress is applied and "peeling" occurs at the interface between the glass fiber and the primary resin coating layer, or "voids" occur due to cracks in the primary resin coating layer. Such a state in which a large deformation is locally generated and a permanent deformation is a phenomenon in which the primary resin coating layer has exceeded the elastic limit. Therefore, a new "stress at 100% elongation" was introduced to evaluate peeling or voids caused by large deformation of the primary resin coating layer. Then a result of various studies, it shows a tendency to stress at 100% elongation of the primary coating resin material voids are generated in the primary coating layer is less than 0.04 kg / mm ^2, occurs peeling it exceeds 0.25 kg / mm ² I understood.

That is, the coated optical fiber of the present invention has
Since the stress at 0% elongation and the adhesive strength to the glass fiber are formed by the primary resin coating material within a predetermined range, the occurrence of interface peeling or voids is suppressed, and
Good coating removability is obtained.

Another coated optical fiber according to the present invention is a secondary optical fiber made of a resin material having an elastic modulus at elongation of 2.5% of not less than 20 kg / mm ^{2 and not} more than 200 kg / mm ^{2 on} the outer periphery of the above coated optical fiber. A resin coating layer is provided.

The primary purpose of the secondary resin coating layer of the present invention is to protect it from an external force applied to the optical fiber. According to the above coated optical fiber, the secondary resin coating layer accounts for 2.5% of the secondary resin coating material. When the elastic modulus in elongation is less than 20 kg / mm ² , an external force is easily propagated to the primary resin coating layer, so that stress propagation to the primary resin coating layer is increased and voids are easily generated. On the other hand, if it exceeds 200 kg / mm ² , flexibility decreases and propagation loss increases.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the coated optical fiber of the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a view showing an optical fiber ribbon according to the present embodiment. In the optical fiber ribbon 6, a plurality (four in FIG. 1) of coated optical fibers 4 are arranged in parallel. It is formed by applying a collective resin coating layer 5 made of an ultraviolet curable resin on the outer periphery.

FIG. 2 is a diagram showing a coated fiber used for an optical fiber ribbon. The coated optical fiber 4 is composed of a primary resin coating layer made of an ultraviolet-curable resin A on the outer periphery of a glass fiber 1 made of quartz glass. 2 are provided. The resin material of the primary resin coating layer 2 has an adhesion to the glass fiber 1 of 30 g / cm or more and 80 g / cm or less, and a stress at 100% elongation of 0.04 kg / mm.
² or more and 0.25 kg / mm ² or less.

In the above-mentioned coated optical fiber 4, the primary resin coating layer 2 and the glass fiber 1 are used to hold the glass fiber 1 on the central axis and suppress the separation.
Has a lower limit of 30 g / cm, and an upper limit of 80 g / cm is required to remove the primary resin coating layer 2 by applying a predetermined force in the axial direction. If the upper limit of the adhesive force is exceeded, the primary resin coating 2 will remain on the surface of the glass fiber 1 when the primary resin coating layer 2 is removed.

Further, according to the study results of the present inventors,
When the primary resin coating layer 2 is provided on the outer periphery of the glass fiber 1 and is wound up via a roller, the fine foreign substances and the like on the roller surface come into contact with the primary resin coating layer 2 and come into contact with the fine foreign substances and the like. It has been found that a large stress is applied to the local portion of No. 2 and peeling occurs at the interface between the glass fiber 1 and the primary resin coating layer 2 or a crack occurs in the primary resin coating layer 2 to generate a void. The state where the large deformation is locally generated and the permanent deformation is generated is caused by the primary resin coating layer 2.
Is a phenomenon in which the elastic limit has been exceeded. Therefore, a stress at 100% elongation was introduced in order to evaluate peeling or voids caused by large deformation of the primary resin coating layer 2.

In order to examine the influence of the rollers in detail,
A screening mechanism provided with a mandrel on the surface is provided in the rewinding machine, and the coated optical fiber 4 is passed over the mandrel, thereby causing interface peeling or voids between the glass fiber 1 and the primary resin coating layer 2 and microscopic observation. Was used to investigate the frequency of occurrence. As a result, the stress at 100% elongation of the primary coating resin material 2 was 0.04 kg / mm ^2.
If it is less than 0.25 kg, voids occur in the primary coating layer 2, and
/ Mm ² , it was found that there was a tendency for peeling to occur.

As the resin A for forming the primary resin coating layer 2, an ultraviolet curable resin such as a urethane acrylate resin, a polyester acrylate resin, or an epoxy acrylate resin is used. Resin A of primary resin coating layer 2
In order to make the adhesion to the glass fiber 1 30 g / cm or more and 80 g / cm or less, for example, the amount of the polar monomer of the resin used for the synthesis of the ultraviolet curable resin A or the amount of the silane coupling agent added Is obtained by adjusting.

The resin A of the primary resin coating layer 2 is 10
The stress at 0% elongation in a 0.04 kg / mm ² or more and 0.25 kg / mm ² or less, for example, by adjusting the addition ratio of the monomer containing resin used in the synthesis of the ultraviolet curable resin A It should be within the above range. Alternatively, a resin obtained by adding a polyfunctional monomer to a resin used for synthesizing the ultraviolet-curable resin A and adjusting the amount of the monofunctional monomer to be used is used. As monofunctional monomers, hydroxyethyl acrylate,
One or two or more selected from ethylhexyl acrylate, N-vinylcaprolactam and the like are used.

FIG. 3 is a view showing a method of removing the primary resin coating layer of the coated optical fiber from the glass fiber under a certain condition. FIG. 3 (a) shows a method before the primary resin coating layer is pulled out of the glass fiber. FIG. 3B is a diagram showing a state, and FIG. First, the tip of the coated optical fiber 4 is fixed on a hard plate 10 made of metal or the like by an adhesive 11. Next, a cut 12 is made in the primary resin coating layer 2 on the hard plate 10 at right angles to the longitudinal direction, and the other end of the coated optical fiber 4 fixed to the hard plate 10 is wound around the drum 13 in the direction of arrow 14. pull. As a result, the hard plate 1
The tubular primary resin coating layer 2 is left on 0, and only the glass fiber 1 is pulled out.

The adhesive strength between the resin material of the primary resin coating layer 2 and the glass fiber 1 is measured using a film-like sample. First, the resin A of the primary resin coating layer 2 is applied on a quartz glass plate whose surface has been washed by immersion in sulfuric acid.
Irradiation with ultraviolet light of mJ / cm ² , thickness 200 μm, width 5
cm film, temperature 25 ° C, relative humidity 50%
And left for one week in an atmosphere to cure and produce a film-like primary resin coating. Next, the film-shaped primary resin coating is peeled off from one end of the quartz glass plate in a direction of 180 degrees at a speed of 200 mm / min. The adhesion is defined by the maximum value (g / cm) of the force per unit width when the primary resin coating is peeled off.

In order to measure the stress of the primary resin coating material at 100% elongation, first, the resin A of the primary coating layer 2 is applied on a polypropylene substrate and irradiated with 100 mJ / cm ² of ultraviolet light to obtain a thickness. A sheet having a thickness of 100 μm and a width of 6 mm is formed and left to cure in an atmosphere at a temperature of 25 ° C. and a relative humidity of 50% for 24 hours to prepare a sheet-like primary coating. Next, a test piece is prepared from the sheet-shaped primary coating according to the standard of JIS K71272, and a rating line is provided at the center at intervals of 25 mm. Using the tensile tester, the strain history with respect to the tensile load is tracked on the produced test piece, and the stress when the elongation between the evaluation lines becomes 100% is measured. The stress is measured according to JIS K7113 standards.

FIG. 4 is a view showing a coated optical fiber of another configuration used for an optical fiber ribbon. The coated optical fiber 4 is formed from a glass fiber 1 and an ultraviolet curable resin A provided on the outer periphery thereof. And a secondary resin coating layer 3 made of an ultraviolet curable resin B. The resin material of the primary resin coating layer 2 has an adhesion to the glass fiber 1 of 30 g / cm or more and 80 g / cm or less, and further has a stress of 0.04 at 100% elongation.
The ultraviolet-curable resin A is not less than kg / mm ^{2 and not} more than 0.25 kg / mm ² and is the same as the resin material of the coated optical fiber shown in FIG.

The primary purpose of the secondary resin coating layer 3 provided on the outer periphery of the primary resin coating layer 2 is to protect it from external force applied to the optical fiber. In order to suppress the elasticity, there is a lower limit of 20 kg / mm ^{2 in} the elastic modulus at 2.5% elongation, and 200 kg / m 2.
An upper limit of m ² is required.

As the resin B for forming the secondary resin coating layer 3, there is an ultraviolet curable resin such as a urethane acrylate resin and a polyester acrylate resin. Resin B is
In order to make the elastic modulus at the time of 2.5% elongation 20 kg / mm ² or more and 200 kg / mm ² or less, for example, the ratio of the monomer contained in the resin used for the synthesis of the ultraviolet-curable resin B is adjusted. Obtained by Alternatively, a resin obtained by adding a polyfunctional monomer to a resin used for synthesizing the ultraviolet-curable resin B and adjusting the amount of the monofunctional monomer to be used is used. As the monofunctional monomer, one or more selected from tetraethylene glycol, N-vinylcaprolactam, isobornyl acrylate, and the like are used.

The method of measuring the elastic modulus at 2.5% elongation is described in J.
This is performed according to the ISK7113 standard. In addition, the change in transmission loss depends on the wavelength 1. before and after the screening test.
The transmission loss at 55 μm was measured using OTDR,
The evaluation was based on the difference between the two. The secondary resin coating layer 4 shown in FIG. 4 is preferably provided with a colored layer on the outer periphery in order to give the coated optical fiber distinctiveness.

[0028]

EXAMPLES The present inventors, based on the above embodiment,
First, as shown in FIG. 2, a coated optical fiber 4 in which a primary resin coating layer 2 is provided on the outer periphery of a glass fiber 1 is produced.
Separation of interface between glass fiber 1 and primary resin coating layer 2, void due to destruction of primary resin coating layer 2, primary resin coating layer 2
The removability was examined. Interfacial delamination and voids
It was examined visually using a microscope. After the coating was removed by the method shown in FIG. 3, the surface of the glass fiber was visually inspected. Table 1 shows the resin A used for the coated optical fiber 4 and the performance of the coated optical fiber 4.

[0029]

[Table 1]

In Table 1, the criteria for peeling, voiding, and removability are indicated by x when there is no peeling, void, and primary resin, respectively, and when there is a little.

(Examples 1 to 5 and Comparative Examples 1 to 4) Diameter 1
A glass fiber 1 made of quartz glass having a diameter of 25 μm is drawn, and an outer diameter 20 made of an ultraviolet-curable resin A is provided around the glass fiber 1.
The coated optical fiber 4 having the configuration shown in FIG. 2 was prepared by providing the primary resin coating layer 2 of 0 μm. The ultraviolet curable resin A adjusts the polar / non-polar monomer amount of the urethane acrylate resin used for the synthesis or the added amount of the silane coupling agent in order to change the adhesion force with the glass fiber 1 and increases the 100% elongation. In order to change the stress in the above, P-1 to P-9 were prototyped by adjusting the diol compound at the time of the synthesis of the primary prepolymer.

In the coated optical fibers 4 of Examples 1 to 3, the resin A forming the primary resin coating layer 2 has an adhesion to the glass fiber 1 of 30 g / cm to 80 g / cm.
And the stress at 100% elongation is 0.1 kg / mm ²
It is. When the performance of these coated optical fibers 4 was examined, no peeling or voids appeared. Also, when the primary resin coating layer 2 was removed from the glass fiber 1 at the tip of the coated optical fiber 4 while being pulled out, the primary resin coating layer 2 did not remain on the surface of the glass fiber 1.

On the other hand, as shown in Comparative Example 1, when the same investigation was carried out with the adhesion of the resin A reduced to 20 g / cm, peeling occurred between the glass fiber 1 and the primary resin coating layer 2. Part existed. Conversely, as shown in Comparative Example 2, the same investigation was performed by increasing the adhesion of the resin A to 100 g / cm. As a result, there was a portion where the primary resin coating layer 2 was fixed to the surface of the glass fiber 1 and remained. .

Further, the coated optical fiber 4 of the fourth to fifth embodiments
In the above, the resin A forming the primary resin coating layer 2 is 10
The stress at 0% elongation is 0.04 kg / mm ^{2 to} 0.2
5 kg / mm ² , and the adhesion to glass fiber 1 is 50 g / cm. When the performance of these coated optical fibers 4 was examined, no peeling or voids appeared. Further, when the primary resin coating layer 2 was removed from the glass fiber 1 at the tip of the coated optical fiber 4 while being pulled out, the primary resin coating layer 2 was fixed to the surface of the glass fiber 1 and no portion remained.

On the other hand, as shown in Comparative Example 3, when the stress at 100% elongation was reduced to 0.03 kg / mm ² and the same investigation was conducted, the void between the glass fiber 1 and the primary resin coating layer 2 was found. Was present.
Conversely, as shown in Comparative Example 4, when the stress at 100% elongation was increased to 0.3 kg / mm ² and the same investigation was performed, a portion peeled between the glass fiber 1 and the primary resin coating layer 2 was found. Existed.

As is clear from the results obtained in the above Examples and Comparative Examples, the adhesion of the resin A of the primary resin coating layer 2 is in the range of 30 g / cm to 80 g / cm, and
% Elongation is 0.04 kg / mm ^{2 to} 0.25
In the range of kg / mm ² , peeling, voiding, and removal of the coated optical fiber are good, and it can be determined that the coated optical fiber is inferior in any other range. On the other hand, when the resin A of the primary resin coating layer 2 was evaluated by the Young's modulus at 2.5% elongation conventionally used, as shown in Table 1, P-1 to P-
-9, the Young's modulus at 2.5% elongation of the resin A is 0.10 kg / mm ^{2 to} 0.15 kg / mm ^2. Cannot be determined according to

Next, as shown in FIG.
To produce a coated optical fiber 4 having a secondary resin coating layer 3 provided on the outer periphery thereof, peeling off the interface between the glass fiber 1 and the primary resin coating layer 2, voids due to destruction of the primary resin coating layer 2, primary resin coating layer 2 and the change in transmission loss before and after the screening test were examined by the OTDR method described above. Table 2 shows the resins A and B used for the coated optical fiber 4 and the performance of the coated optical fiber 4.

[0038]

[Table 2]

In Table 2, the criteria for peeling, voids, and removability are indicated by x when there is no peeling, voids, and primary resin, respectively, and when there is at least a little.

(Examples 6 and 7 and Reference Examples 1 and 2) Diameter 1
A glass fiber 1 made of quartz glass having a diameter of 25 μm is drawn, and an outer diameter 20 made of an ultraviolet-curable resin A is provided around the glass fiber 1.
A coated optical fiber 4 having the configuration shown in FIG. 4 and having a primary resin coating layer 2 of 0 μm and a secondary resin coating layer 3 having an outer diameter of 255 μm and having an identification layer on the outermost periphery was produced.

The UV-curable resin B used for the secondary resin coating layer 3 is prepared by adjusting the monomer ratio of the urethane acrylate resin in order to change the elastic modulus at 2.5% elongation. -4 was prototyped. An epoxy acrylate resin was used for the identification layer. The ultraviolet curable resin A used for the primary resin coating layer 2 is the same as P-3 shown in Table 1.

In the coated optical fibers 4 of Examples 6 and 7, the primary resin coating layer 2 is a single layer resin P-3 having good properties as shown in Table 1, and the secondary resin coating layer 2 is a single resin coating layer. Layer 3 has an elastic modulus of 20 kg / mm ² at 2.5% elongation.
Resins Q-2 and Q-3 of ２００200 kg / mm ² . When the peeling between the glass fiber 1 and the primary resin coating layer 2 and the voids due to the cracks in the primary resin coating layer 2 were examined for these coated optical fibers 4, no peeling or voids appeared. In addition, when the primary resin coating layer 2 and the secondary resin coating layer 3 were removed from the glass fiber 1 while being pulled out from the tip of the coated optical fiber 4, the primary resin coating layer 2 did not remain on the surface of the glass fiber 1. Was.

On the other hand, as shown in Reference Example 1, the elastic modulus at 2.5% elongation of the secondary resin coating layer 3 was 15 kg / mm.
^When the same investigation was performed on the resin Q-1 reduced to ² , the primary resin coating layer 2 had a portion where a crack was formed and a void was formed. Conversely, as shown in Reference Example 2,
The elastic modulus at 2.5% elongation of the secondary resin coating layer 3 is 25.
A similar study was conducted on resin Q-4, which was increased to 0 kg / mm ^2, and the increase in transmission loss was 0.2 dB / k.
m.

Further, an optical fiber tape core 6 shown in FIG. 1 was produced by using the collective resin coating layer 5 while arranging the four coated optical fibers 4 shown in FIG. 4 in parallel. The ultraviolet curable resin used as the collective resin coating layer 5 was adjusted for the crosslink density and urethane group of the urethane acrylate resin in order to give the secondary resin coating layer 3 an appropriate adhesion. The resin material of the primary resin coating layer 2 has an adhesion to a glass fiber of 30 g / cm or more and 80 g / cm or less, and a stress at 100% elongation of 0.04 kg / mm ^2.
It is not less than 0.25 kg / mm ² . The resin material of the secondary resin coating layer 3 has an elastic modulus of 20 at 2.5% elongation.
kg / mm ² or more and 200 kg / mm ² or less. As a result of investigating the performance of the optical fiber ribbon 6 thus manufactured, the coated optical fiber 4 did not cause peeling or voids, and was excellent in coating removal properties and transmission loss. .

[0045]

The present invention introduced "stress at 100% elongation" as a requirement of the primary resin coating material used for the coated optical fiber. Since the coated optical fiber of the present invention is formed by the primary resin coating material in which the stress at 100% elongation and the adhesive force to the glass fiber are within a predetermined range, the generation of interface peeling or voids is suppressed, and the coating removal property is also improved. Good characteristics are obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical fiber ribbon according to an embodiment.

FIG. 2 is a view showing a coated optical fiber according to the embodiment.

FIG. 3A is a diagram illustrating a state before removing a coating layer of a coated optical fiber, and FIG. 3B is a diagram illustrating a state after removing the coating layer.

FIG. 4 is a diagram showing another coated optical fiber according to the embodiment.

FIG. 5 is a view showing a conventional optical fiber ribbon.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass fiber, 2 ... Primary resin coating layer, 3 ... Secondary resin coating layer, 4 ... Coated optical fiber, 5 ... Collective resin coating layer, 6 ... Optical fiber tape Core wire, 10 ... hard plate, 1
1 ... adhesive, 12 ... cut, 13 ... drum, 14 ...
.. Arrows.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomoyuki Hattori 1-chome, Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 2H050 AB02Z BA32 BB05Q BB07Q BB07S BB13Q BB13S BB14Q BB14S BB17Q BB17S BB31Q BB31S BB33Q BB33S BC03 BD00 4G060 AC02 AC12 AC15 CB22 CB33

Claims (2)

[Claims] 1. A coated optical fiber in which a primary resin coating layer is provided on the outer periphery of a glass fiber, wherein the resin material of the primary resin coating layer has an adhesive force with the glass fiber of 30.
g / cm or more and 80 g / cm or less.
Stress at 100% elongation 0.04 kg / mm ² or more and 0.25 kg / mm ² coated optical fibers, wherein less. 2. The outer periphery of the coated optical fiber according to claim 1, further comprising a secondary resin coating layer made of a resin material having an elastic modulus at 2.5% elongation of 20 kg / mm ² or more and 200 kg / mm ² or less. A coated optical fiber provided.