JPH1048492A - Manufacturing method of ribbon type optical fiber - Google Patents

Abstract

[PROBLEMS] When an optical cable using a ribbon-type optical fiber 1 is used in a high-temperature and high-humidity state, not only the interface between the coloring layer 4 and the collective coating layer 2 but also the coloring layer 4 and the primary coating. When the interface with the layer 6 was partially peeled off and water was accumulated, it was subjected to uneven microbending. SOLUTION: The adhesion between a protective coating layer 6 made of an ultraviolet-curable resin provided on the outer periphery of a glass fiber 7 and a colored layer 4 made of an ultraviolet-curable resin provided thereon is strengthened. This is a method which is improved by a chemical bond of carbon-carbon bonds at the contact surface between the protective coating layer 6 and the coloring layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a ribbon type optical fiber housed in an optical cable.

[0002]

2. Description of the Related Art Conventionally, in order to house optical fibers at a high density in an optical cable, a ribbon type optical fiber constituted by a plurality of colored optical fiber cores is bundled in a slot of a spacer. A method of accommodating and covering this with a sheath to form an optical fiber cable has been performed.

FIG. 1 shows a ribbon-type optical fiber used for such an optical cable.
A plurality of colored optical fiber cords 3 are arranged in parallel and covered with a collective coating layer 2 made of an ultraviolet curable resin, and the cross-sectional shape thereof is flat. The optical fiber colored core 3 is formed by coating an outer peripheral surface of a glass fiber 7 with a primary coating layer 6 to form an optical fiber 5, and furthermore, an ultraviolet curable resin containing a coloring agent on the outer peripheral surface of the primary coating layer 6. The optical fiber core wire 3 is formed by covering the colored layer 4 made of

[0004]

By the way, even if an optical cable using the ribbon type optical fiber 1 is used in a high temperature and high humidity state, the transmission loss of the colored optical fiber 3 is not directly deteriorated by moisture. However, if it is immersed in water that has penetrated into the cable due to breakage or the like for a long period of time, the interface between the colored layer 4 of the colored optical fiber core 3 and the collective coating layer 2 or between the colored layer 4 and the primary coating layer 6 The interface partially peels off,
Moisture may accumulate in the peeled portion, causing local swelling. When such swelling occurs, the optical fiber colored core wire 3 receives uneven microbends in its longitudinal direction, and there is a disadvantage that transmission loss increases.

Conventionally, as a countermeasure against such a problem, attention has been paid to the interface between the colored layer 4 and the collective coating layer 2 to make the moisture permeability of the ultraviolet-curable resin forming the colored layer 4 and the collective coating layer 2 constant. In this way, a method of preventing local accumulation of water (Japanese Patent Laid-Open No. 3-192315), or by limiting the upper limit of the adhesive force between the colored layer 4 and the collective coating layer 2 is achieved. 3 has been devised (JP-A-7-31324), in which the composition 3 is configured to be easily divided from the collective coating layer 2 and is dispersed in the length direction even if water enters.

However, when not only the interface between the colored layer 4 and the collective coating layer 2 but also the interface between the colored layer 4 and the primary coating layer 6 is partially separated and water is collected, as described above, the glass fiber 7 Undergo non-uniform microbends. In addition, since the microbend in this case is close to the glass fiber 7, the influence is increased accordingly.

Accordingly, an object of the present invention is to provide a ribbon type optical fiber which has solved the problem of the interface between the colored layer and the primary coating layer.

[0008]

According to the present invention, there is provided a method of manufacturing a ribbon-type optical fiber, comprising: coating an outer periphery of a drawn glass fiber with a first resin of an ultraviolet curing type for forming a protective coating layer. And a first step of forming a protective coating layer of the optical fiber by controlling ultraviolet rays applied to the first resin to such an extent that a predetermined amount of carbon-carbon double bonds remain on the surface;
An ultraviolet-curable second resin to which a coloring pigment is added is applied to the outer periphery of the optical fiber, and the second resin is cured by irradiating ultraviolet rays with ultraviolet rays, and is allowed to pass therethrough so that a predetermined amount of carbon-carbon resin is left. Forming a plurality of colored optical fibers by reacting the heavy bond with the second resin to form a chemical bond;
And a third step of arranging a plurality of colored optical fibers in parallel on the same plane and integrally forming them with a collective coating layer of an ultraviolet curable resin.

According to the production method of the present invention, the carbon-carbon double bonds which disappear by irradiating the surface of the protective coating layer with ultraviolet rays are restricted, and a certain amount of carbon-carbon double bonds is left. Furthermore, the resin for the coloring layer applied thereon is applied, and is irradiated with ultraviolet rays to react with the remaining carbon-carbon double bond to form a chemical bond, thereby bonding the protective coating layer and the coloring layer. Power can be increased. By increasing the adhesive force between the protective coating layer and the coloring layer which are closest to the glass fiber 7, the separation due to the intrusion of moisture can be prevented and the generation of microbends can be suppressed.

In the first step of the present invention, the residual amount of carbon-carbon double bonds on the surface of the protective coating layer of the optical fiber is usually realized by a method of controlling the power or irradiation time of an ultraviolet irradiation lamp. In order to effectively increase the adhesive strength between the protective coating layer and the coloring layer, it is preferable that the ratio of the remaining carbon-carbon double bond is 3% or more. In order to hold the shape by holding it, it is desirable to control it to 25% or less.

The Young's modulus of the cured protective coating layer is as follows:
From the viewpoint of maintaining the strength, 40 kg / mm ² or more is required, which is achieved by, for example, reducing the molecular weight of the oligomer or using a polyfunctional monomer.

The first step in the present invention includes a step of measuring the ratio of carbon-carbon double bonds remaining on the surface of the protective coating layer, and the residual amount is controlled based on the measurement result. The carbon-carbon double bond is measured by irradiating the ultraviolet-curable resin with ultraviolet light so that the carbon-
This is a method of judging the disappearance of carbon double bonds based on the absorption spectrum.The area occupied by the spectrum distribution of the absorption peak that does not change with the progress of curing and the absorption peak reflecting the number of carbon-carbon bonds as curing progresses. Where SR is the ratio of the area of the spectral distribution of the peak to SR, the area ratio of the uncured resin is SR (uncured), and the disappeared carbon-carbon dioxide when the area ratio of the target sample is SR (sample). The heavy bond C is expressed as C = {SR (uncured) −SR (sample)} / SR (unc
ured), and the remaining carbon-carbon double bond CD is represented by the following formula: CD = (1-C) × 100 (%) This is because the evaluation can be performed accurately and easily. The amount of light transmitted through the second resin in the second step of the present invention is adjusted by controlling the thickness of the second resin. If the thickness is too small, the discrimination effect due to coloring decreases, so that the light amount is required to be 3 μm or more.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A ribbon type optical fiber according to the present invention is different from a conventional ribbon type optical fiber in that, in FIG. 1, a protective coating layer made of an ultraviolet curable resin is provided on the outer periphery of a glass fiber 7. 6 and the colored layer 4 made of an ultraviolet curable resin provided thereon is strengthened in adhesion, and this is used to improve the carbon-carbon bond at the contact surface between the protective coating layer 6 and the colored layer 4. It is realized by chemical bonding.

An embodiment of a method for manufacturing a ribbon-type optical fiber according to the present invention will be described below with reference to FIGS.

The first step of the present invention is a step of preparing the optical fiber 5, wherein the optical fiber preform 10 made of quartz glass is heated by the heating device 11 at the same time.
Glass fiber 7 for optical transmission spun from the tip of base material 10
Is formed, and the glass fiber 7 is inserted into a coating die 12-1 provided immediately below the heating device 11, and an ultraviolet curable resin serving as the protective coating layer 6 is applied. Next, the resin is cured by passing through an ultraviolet irradiation device 13-1 provided immediately below the coating die 12-1, and the protective coating layer 6 of the optical fiber 5 is formed. At this time, in the present embodiment, a predetermined amount of carbon-carbon double bonds remains on the surface of the protective coating layer 6 so that the carbon-carbon double bonds have a predetermined positive value with respect to the carbon-carbon double bonds that have disappeared by irradiation with ultraviolet light. Is controlled.

The residual amount (or residual ratio) of the carbon-carbon double bond is usually adjusted by the power or drawing speed of the ultraviolet irradiation device 13-1.

The UV-curable resin used for the protective coating layer 6 is a UV-curable urethane acrylate resin,
An ultraviolet-curable resin such as an ultraviolet-curable epoxy acrylate resin and a mixture thereof are used.

Next, the state where the carbon-carbon double bond near the surface is absorbed and annihilated by irradiating the surface of the protective coating layer 6 with ultraviolet rays is determined. This will be described with reference to FIG. 4 showing the distribution of the number of carbon-carbon bonds. In the figure, the absorption peak that does not change depending on the progress of curing (1 / λ ₁ )
And the area A, B, or C of the spectrum distribution a, b, or c of the absorption peak (1 / λ ₂ ) that reflects the number of carbon-carbon bonds as the curing progresses. When the ratio is SR, the area ratio of the uncured resin is SR (uncured), and the area ratio of the target sample is SR (s
ample), the disappeared carbon-carbon double bond C is C = {SR (uncured) -SR (sample)} / SR (unc
ured), and the remaining carbon-carbon double bond CD is represented by the following formula: CD = (1-C) × 100 (%)

The second step of the present invention is a step of forming the optical fiber core wire 3 by coating the optical fiber 5 having a predetermined value of the carbon-carbon double bond with the coating die 12-2.
And by passing through the ultraviolet irradiation device 13-2, titanium white (white) and cyanine blue (blue)
UV curable resin to which a coloring pigment such as, for example, is applied, is applied.
To form Here, the protective coating layer 6 of the optical fiber 5
As shown in FIG. 5, the chemical bond between the color layer 4 and the ultraviolet rays 21 transmitted through the color resin layer 4-1 for forming the color layer appears on the surface of the color resin layer 4-1. Carbon double bond 20-2 and carbon remaining on the surface of protective coating layer 6
The carbon double bond 20-1. Therefore, the thickness of the coloring layer 4 needs to be within a range that does not cause harm to the carbon-carbon double bond that transmits the ultraviolet rays 21 and terminates at the interface with the protective coating layer 6. .
If the thickness is too large, the ultraviolet rays 21 are absorbed while passing through the colored resin layer 4-1.

The third step of the present invention is a step of forming the ribbon-type optical fiber 1, in which a plurality of colored optical fiber cores 3 are prepared, and these are coated on a plane and parallel to a coating die 12-3. , The UV curable resin is collectively coated, and then the UV irradiation device 12
-3, and the resin is cured to form a ribbon-type optical fiber 1 similar to that shown in FIG.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples. Using the device shown in FIG. 2 and FIG.
An outer diameter of 25 μm is applied to the bare single mode optical fiber 7 of 5 μm.
A protective coating layer 6 is formed by applying a 0 μm epoxy acrylate-based UV-curable resin and subsequently irradiating UV rays, and adjusting the power and linear velocity of the UV lamp to a predetermined ratio on the surface of the protective coating layer 6. A carbon-carbon double bond was left. Next, an optical fiber colored cord 3 having a coloring layer 4 using a resin obtained by adding 5 parts by weight of cyanine blue to 100 parts by weight of an epoxy acrylate-based ultraviolet curable resin.
Was prepared. Further, four optical fiber colored core wires 3 are prepared, and these are coated in parallel and in a plane by adding 7 parts by weight of a silicone oil release agent to a urethane acrylate-based UV-curable resin and collectively coating the UV light. Irradiation gave a four-core ribbon-type optical fiber 1 similar to that of FIG.

[0022]

[Table 1]

As described above, Table 1 shows the transmission loss after a ribbon-type optical fiber was manufactured by means of bonding carbon-carbon double bonds and immersed in warm water at 60 ° C. for two weeks. Transmission loss was measured at a wavelength of 1.55 μm using OTDR.

In Samples 1 to 5, as the number of residual carbon-carbon double bonds increases, the adhesive force increases and the peeling does not occur between the colored layer and the protective coating layer. The coating layer becomes sticky and suffers external damage when passing through a guide roller or the like. On the contrary, too little 3
% Or less, the adhesive strength was weakened, peeling occurred, and water was easily accumulated, and transmission loss increased.

As shown in Sample 6, the Young's modulus of the protective coating layer was required to be 40 kg / mm ² , and if it was less than that, the lateral pressure characteristics deteriorated and the transmission loss increased. This side pressure test was performed on a winding bobbin with a body diameter of 285 mm.
The evaluation was made based on the change in transmission loss when 40 sandpapers were wound and further wound at a winding tension of 300 g.

The minimum thickness required for the colored layer was determined depending on whether or not the color of the colored core could be distinguished.
As a result, as shown in Samples 7 and 8, it was found that a thickness of 3 μm or more was necessary, and if the thickness was thinner, color identification became impossible.

[0027]

According to the method for producing a ribbon-type optical fiber according to the present invention, the carbon-carbon double bond remaining on the surface of the protective coating layer is irradiated with ultraviolet rays to the coloring layer resin applied thereon. By irradiating and acting, the adhesive strength between the protective coating layer and the colored layer can be increased. By increasing the adhesive force between the protective coating layer and the colored layer that are in close proximity to the glass fiber, it is possible to prevent peeling due to intrusion of moisture and suppress the generation of microbends.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a ribbon-type optical fiber.

FIG. 2 is an explanatory diagram of first and third steps for manufacturing a ribbon-type optical fiber.

FIG. 3 is an explanatory view of a fourth step for manufacturing a ribbon-type optical fiber.

FIG. 4 is a diagram showing the distribution of the number of carbon-carbon bonds that changes when an ultraviolet-curable resin is irradiated with ultraviolet light.

FIG. 5 is a diagram for explaining a chemical bond between a protective coating layer and a coloring layer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ribbon type optical fiber, 2 ... Collective coating layer, 3 ... Optical fiber colored core wire, 4 ... Colored layer, 4-1 ... Colored resin layer, 5 ... Optical fiber Element wire, 6: protective coating layer (primary coating layer), 7: glass fiber, 10: optical fiber preform,
11 ... heating device, 12 ... coating die, 13 ...
・ Ultraviolet irradiation device, 14 ・ ・ ・ Guide roller, 15 ・ ・ ・ Winding bobbin, 20 ・ ・ ・ Carbon-carbon double bond, 21 ・ ・ ・ Ultraviolet

Claims (5)

[Claims] 1. An ultraviolet-curable first resin for forming a protective coating layer is applied to the outer periphery of a glass fiber formed by drawing, so that a predetermined amount of carbon-carbon double bonds remains on the surface. A first step of forming a protective coating layer of the optical fiber by controlling the ultraviolet light applied to the first resin, and a second ultraviolet curing type in which a coloring pigment is added to the outer periphery of the optical fiber. A resin is applied, and the second resin is cured by irradiating ultraviolet rays with ultraviolet light, and is allowed to pass therethrough so that the carbon-carbon double bond left in a predetermined amount and the second resin react with each other to form a chemical bond. A second step of forming a plurality of colored optical fiber cores, and a third step of arranging the plurality of optical fiber colored cores in parallel on the same plane and integrally forming them with a collective coating layer of an ultraviolet curable resin. And a ribbon type optical fiber. Method of manufacturing a driver. 2. The method according to claim 1, wherein in the first step, the residual amount of carbon-carbon double bonds on the surface of the protective coating layer of the optical fiber is controlled by the power or irradiation time of an ultraviolet irradiation lamp. 2. The method for producing a ribbon-type optical fiber according to item 1. 3. The ribbon according to claim 1, wherein, in the first step, the ratio of carbon-carbon double bonds remaining on the surface of the protective coating layer is controlled to 3 to 25%. Of manufacturing optical fiber. 4. The method according to claim 1, wherein the first step includes a step of measuring a ratio of carbon-carbon double bonds remaining on the surface of the protective coating layer, and the residual amount is controlled based on the measurement result. The method for producing a ribbon-type optical fiber according to claim 1. 5. The method of measuring the ratio of the remaining carbon-carbon double bonds in the first step, wherein the carbon-carbon double bonds near the surface disappear by irradiating the ultraviolet-curable resin with ultraviolet rays. This is a method of judging the state from the absorption spectrum, in which the area occupied by the spectrum distribution of the absorption peak that does not change with the progress of curing and the area of the spectrum distribution of the absorption peak reflecting the amount of carbon-carbon bonds as the curing progresses When the ratio is SR, the disappeared carbon-carbon double bond C when the area ratio of the uncured resin is SR (uncured) and the area ratio of the target sample is SR (sample) is C = 、 SR (Uncured) -SR (sample)｝ / SR (unc
5. The method for producing a ribbon-type optical fiber according to claim 4, wherein the remaining carbon-carbon double bond CD is represented by CD = (1−C) × 100 (%). .