JPH05241052A - Coated optical fiber - Google Patents

Abstract

PURPOSE:To prevent the abnormal bulging of a colored layer and to prevent an increase in the transmission loss of an optical fiber by using specific ink as the ink to be used for the colored layer or using a specific sensitizer as the sensitizer to be added into the ink. CONSTITUTION:The colored and coated optical fiber 4 is constituted by applying a primary coating layer 2 on the outer periphery of an optical fiber 1 and further the colored layer (secondary coating layer) on the outer periphery thereof. Plural pieces of such colored and coated fibers 4 are arrayed horizontally and the lump coating is applied thereon, by which the tape-like coated optical fiber is produced. The ink, the weight change of which when immersed into water is below 3% within the temp. range where the tape-like coated optical fiber is used is used as the ink to be used for the colored layer 3. The sensitizer having the low solubility in the water within the temp. range where the tape-like coated optical fiber is used is used as the sensitizer to be used in the ink if the ink is UV curing type ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber core wire used for optical communication or the like, and more particularly to an optical fiber core wire having a colored layer.

[0002]

2. Description of the Related Art In an optical fiber used for optical communication,
Not limited to optical glass fiber and silica glass fiber,
It is said that it is preferable to apply a plastic coating (primary coating) to the outer periphery of each of the fibers immediately after they are formed into fibers. This is to prevent the strength of the fiber from lowering due to scratches on the surface of the fiber caused by forming the fiber and growth of cracks due to exposure of the bare fiber to the air. As such a plastic layer, a thermosetting silicone resin, an ultraviolet curable resin (hereinafter referred to as “UV resin”), a radiation curable resin or the like is generally used, and in recent years, a UV resin has been often used. There is.

Microbending of glass, which deteriorates the transmission characteristics of an optical fiber, is caused by various stresses from the outside, and the coating also plays an important role in protecting the optical fiber from them, and in general, it is an inner layer. In many cases, a so-called two-layer coating structure is used in which a resin having a relatively low Young's modulus is used as a buffer layer, and a resin having a relatively high Young's modulus is used as a protective layer in the outer layer. For example, an optical fiber using UV resin (hereinafter referred to as UV resin-coated optical fiber) is an optical fiber melted and drawn from a preform by a drawing furnace, and continuously coated with UV resin using a coating die, Then, it is manufactured by irradiating ultraviolet rays to cure the applied UV resin. Further, such a UV resin-coated optical fiber is further subjected to secondary coating singly or in combination to form an optical fiber core wire. As a secondary coating layer, one U is used for identification.
A colored layer may be coated on the V resin-coated optical fiber, which is called a colored core wire. The ink used as the colored layer may be an ink that is cured by ultraviolet rays (hereinafter referred to as an ultraviolet curable ink) or a heat-curable ink. A thermosetting ink or the like that is cured by is generally used.

[0004]

As a structure suitable for a high-density cable, a plurality of the colored core wires are arranged side by side, and the outside thereof are collectively covered with a UV resin or the like to form a tape-shaped optical fiber core. Lines are used. When this tape-shaped optical fiber core wire is used in a high-humidity atmosphere, the transmission loss may increase extremely. As a result of various studies on the cause, abnormal swelling due to moisture absorption occurs between the primary coating layer and the secondary coating layer, or between the secondary coating layer and the collective coating layer. It turned out to be stressful and thus increase loss.

[0005]

[Means for Solving the Problems] The above-mentioned abnormal swelling is eliminated, and even if the tape-shaped optical fiber core wire is flooded due to some accident, even if it is used for a long time in a high-humidity atmosphere, As a result of various research and development in order to obtain a tape-shaped optical fiber core wire that does not increase the transmission loss,
The weight change when the ink used for the secondary coating layer, which is the colored layer, is immersed in water is less than 3% within the temperature range in which the tape-shaped optical fiber core wire is used, or the ink used Is a UV curable ink, it is preferable to use a sensitizer having a small solubility in water within the temperature range in which the tape-shaped optical fiber core is used as the sensitizer used in the ink. The inventors have found that it is effective and completed the present invention. In the case of a single-component sensitizer, the solubility in water is 0.2 (g / 1
Liter) or less, and in the case of a multi-component sensitizer, the solubility of some of them is 0.2 (g / 1
Liter) or less. Examples of the sensitizer that reduces the water absorption of the ink and the sensitizer that has a low solubility include 2-n-butoxyethyl-4-dimethylbenzoate and ethyl P-dimethylaminobenzoate.

[0006]

[Function] The mechanism for causing the above-mentioned abnormal blistering phenomenon is considered as follows. That is, when the tape-shaped optical fiber core is left in an atmosphere of high humidity, moisture permeates the collective coating and reaches the interface between the secondary coating layer and the collective coating layer, and the secondary coating layer and the primary coating layer. To do. At this time, there are microscopically unbonded portions (voids) at these interfaces, and the permeated water collects and condenses in these voids.
When the sensitizer contained in the ink, which is the secondary coating layer, is dissolved in the condensed water, the force (osmotic pressure) for diluting this concentration naturally acts, and the penetration of water is accelerated. Finally, it becomes an abnormal blistering phenomenon.

The ink used for the secondary coating layer generally comprises an acrylic oligomer reactive diluent, an initiator, a sensitizer, a pigment and the like. The sensitizer is an indeterminate component for increasing the curing speed of the ink, but even after the ink is cured to form a three-dimensional mesh, it is not incorporated into this mesh and absorbs water or water. Can be dissolved by. If dissolved in the water in the void, it causes an abnormal blistering phenomenon as described above. The present invention uses a sensitizer having a small water absorption and a low solubility in water to prevent the abnormal blistering phenomenon by suppressing the absorption of the sensitizer into water in the water or voids, and as a result, The feature is to prevent an increase in transmission loss.

[0008]

[Example] 2 of UV curable urethane acrylate resin
On the primary coating layer composed of layer coating, colored core wires A and B were formed as secondary coating layers by using an ink whose weight change before and after immersion in warm water at 60 ° C. was small. Further, four of these colored cords were arranged side by side, and their outer circumferences were collectively covered to produce a tape-shaped optical fiber cord. As a comparison, colored cores C, D, and E were formed as secondary coating layers using an ink whose weight change before and after immersion in warm water at 60 ° C. was made, and four colored cores each were transversely arranged. Then, the outer circumferences of them were collectively covered to prepare a tape-shaped optical fiber core wire. Table 1 shows the weight change due to water absorption of the ink used for these colored cords. 6
The weight change before and after immersion in warm water at 0 ° C. is defined as follows. That is, the weight of the cured ink film is 60 ° C.
Left in a constant temperature bath for 1 day to fully dry and then measure (W
o) Then, soak in hot water at 60 ° C. for 1 day, take out, leave for one day again in a constant temperature bath at 60 ° C. for drying, and measure the weight (Wa). Then, the change in weight is calculated as shown in Equation 1.

[0009]

[Equation 1]

[0010]

[Table 1]

[0011]

[Table 2]

Next, on the primary coating layer consisting of a two-layer coating of a UV-curable urethane acrylate resin, 6
Colored cords F and G were formed as secondary coating layers using an ultraviolet curable ink containing a sensitizer having a small amount of dissolution in 1 liter of water at 0 ° C. Further, four of these colored cords were arranged side by side, and their outer circumferences were collectively covered to produce a tape-shaped optical fiber cord. For comparison, colored cores H and I were formed as secondary coating layers using an ultraviolet-curable ink containing a sensitizer having a large amount of dissolution in 1 liter of water at 60 ° C. The tape-shaped optical fiber core wires were produced by arranging them side by side and coating the outer circumferences of them all together. Table 2 shows the amount of the sensitizer in the ink used for these colored cords dissolved in water at 60 ° C.

[0013]

The tape-shaped optical fiber core wire using the colored core wires A to E produced by the above-mentioned procedure is set at 60 ° C. and a relative humidity of 9
The transmission loss after standing for 3 days in an atmosphere of 5% is 1.5
It was measured in the 5 μm band. As a result, in the case of Comparative Examples 1 to 3 using the ink having a large weight increase by immersion in 60 ° C. warm water, the transmission loss was 0.30 dB / km and 0.55 dB / k, respectively.
m, increased by 0.25 dB / km, and as a result of investigating the cross section,
Abnormal swelling was observed as shown in 7 of FIG. However, in each of Examples 1 and 2 using the ink whose weight increase due to immersion in 60 ° C. warm water was small, the increase in transmission loss was 0.0.
It was 5 dB / km or less, and no abnormal swelling was observed when the cross section was examined.

Further, the tape-shaped optical fiber cord using the colored fibers of FI was immersed in warm water at 40 ° C. for 5 days, and then the transmission loss was measured in the 1.55 μm band. As a result, 60 ℃
In Comparative Examples 4 and 5 in which the sensitizer having a large amount of dissolution in hot water was used, the transmission loss was 1.9 dB / km and 1.
As a result of examining the cross section, an abnormal swelling was observed as shown by 7 in FIG. But 60
In the case of Examples 3 and 4 in which the sensitizer having a small amount of dissolution in warm water at ℃ was used, the increase in transmission loss was 0.05 dB / km or less, and no abnormal blistering was observed even when the cross section was examined. ..

[Brief description of drawings]

FIG. 1 is a sectional view of an optical fiber colored core wire.

FIG. 2 is a cross-sectional view of a tape-shaped optical fiber core wire.

FIG. 3 shows a tape-shaped optical fiber core after being left in a high-humidity atmosphere, in the case where a coloring layer having a large water absorption amount of ink or a sensitizer in the ink having a low solubility in water is used. Here is an example:

[Explanation of symbols]

 1: Optical fiber 2: Primary coating layer 3: Secondary coating layer (colored layer) 4: Optical fiber colored core wire 5: Collective coating layer 6: Tape-shaped optical fiber core wire 7: Abnormal swelling part

Claims (4)

[Claims] 1. An optical fiber coloring core wire comprising a primary coating layer on the outer circumference of an optical fiber and a coloring layer (secondary coating) on the outer circumference thereof, wherein the coloring of the optical fiber is used as ink for the coloring layer. An optical fiber core wire comprising an ink, the weight change of which is less than 3% due to water immersion within the temperature range used for the ink. 2. A sensitizer to be added to ink as a coloring layer in an optical fiber colored core wire in which a primary coating layer is provided on the outer circumference of the optical fiber and a coloring layer (secondary coating) is further provided on the outer circumference thereof. An optical fiber core wire characterized by using a sensitizer having a low solubility in water. 3. A sensitizer to be added to ink as a coloring layer in an optical fiber colored core wire in which a primary coating layer is provided on the outer circumference of the optical fiber and a coloring layer (secondary coating) is further provided on the outer circumference thereof. When a single component is used, the component itself is used, and when a plurality of components are used as a sensitizer added to the ink as the coloring layer, a part of them is used by the optical fiber colored core wire. The optical fiber core wire is characterized by using a material which does not dissolve 0.2 (g / 1 liter) or more in water within the temperature range used for the above. 4. Claim 1 or claim 2 or claim 3.
2. A tape-shaped optical fiber core wire obtained by arranging a plurality of the optical fiber core wires described in 1 above horizontally and collectively coating them.