JP2003057508A - Coated optical fiber ribbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated optical fiber ribbon which never has its coating broken when its ribbon batch-coating layer is removed. SOLUTION: The coated optical fiber ribbon constituted by arranging a plurality of colored coated optical fibers each formed by providing a primary coating layer, a secondary coating layer, and a colored layer around an optical fiber in parallel and uniting them by coating them with the batch-coating layer is characterized by that the value K obtained by dividing the total of the products of sectional secondary moments and Young's moduli of the primary coating, layer, secondary coating layer, and colored layer by the product of the optical fiber adhesive strength of the primary coating material and the number of the optical fibers of the ribbon is >=1.7 in an atmosphere of heating temperature in the removal of the batch-coating layer of the coated optical fiber ribbon.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber ribbon, and more particularly, to a method of removing a coating layer of an optical fiber ribbon without removing the coating layer. BACKGROUND OF THE INVENTION In recent years, the demand for large-capacity data transmission has been increasing.
In particular, the FTTH (Fiber to the homing)
e) The demand for conversion is rapidly increasing, and the laying of optical cable networks is urgent. As these optical cables, an optical fiber cable having a structure in which a plurality of optical fiber ribbons in which a plurality of optical fiber ribbons are integrated in a tape shape and stored in a state of being stacked in a slot is used. FIG. 1 is a sectional view of an optical fiber core 1 used for such an optical fiber cable for an optical cable network. The optical fiber core 1 has a fiber coating layer 8 formed on the outer peripheral surface of the bare optical fiber 2. The fiber coating layer 8 includes a primary coating layer 3 formed of an ultraviolet-curable resin on the outer peripheral surface of the bare optical fiber 2, a secondary coating layer 4 formed of an ultraviolet-curable resin on the outer periphery thereof, and an outer peripheral surface thereof. Colored layer 5 formed of colored ultraviolet curable resin
It is composed of FIG. 2 is a cross-sectional view of an optical fiber ribbon 7 in which a plurality of optical fibers 1 shown in FIG. 1 are arranged and integrated into a tape by a collective coating layer 6 made of an ultraviolet curable resin. When the tape cores 7 are connected to each other, first, the collective coating layer 6 and the fiber coating layer 8 are collectively removed from a terminal of the tape core 7 by a heating type coating layer removing device. Thereafter, the bare optical fiber 2 is cut by a fiber cutter, and finally, the bare optical fiber 2 is joined and fused. FIG. 3 shows an example of the tape core end portion after the collective coating layer 6 and the fiber coating layer 8 have been collectively removed from the tape core end. FIG. 3A shows a state in which the entire coating layer has disappeared in its original shape without collapse after the removal of the coating layer. Ideally, the entire coating layer can be removed in this way. However, the bare optical fiber 2 and the primary coating layer 3
If the adhesive force of the coating layer is extremely strong compared to the rigidity of the coating layer, the coating layer 8 cannot completely resist the compressive stress at the time of removing the coating layer, and the entire coating layer is destroyed, thus forming a bellows shape as shown in FIG. In some cases, the fiber coating layer 8 may be bent or the coating layers may be peeled off from each other to leave a part of the fiber coating layer 8 on the bare optical fiber 2. Therefore, from the viewpoint of the connection work, when the collective coating layer is removed as shown in FIG.
As shown in (a), the entire fiber coating layer does not lose its shape and falls out in a pipe shape as it is, and the optical fiber tape core wire does not leave the coating resin on the bare optical fiber 2. Is desirable. On the other hand, as described above, an increase in data traffic has led to an increase in the number of cable mounting cores and a reduction in the diameter of an optical fiber cable for an optical cable network.
For this reason, the integration efficiency has been improved by reducing the thickness of the fiber coating layer 8. In recent years, optical fiber cores 1 exported overseas have been taped by foreign manufacturers and used for cables. Optical fiber tapes used overseas are generally used in Japan. The collective coating layer 6 is thinner than the existing optical fiber tape core wire, and the coating is easily broken. Further, the conventional optical fiber cable has been mainly used in a so-called trunk system for connecting telephone offices. However, the FTTH system requires that the optical fiber cable be laid from the telephone office to the terminal home. means. Therefore, the opportunity of exposing the cable after laying to various unconventional environments greatly increases. Exposure to such an adverse environment may damage the sheath of the optical fiber cable and cause water to enter the cable, leaving the optical fiber in a flooded state for a long time. Become. [0008] It has been reported that the loss of an optical fiber increases due to flooding. If the optical fiber core is submerged for a long time, the submersion may cause, for example, the bare optical fiber 2
Separation occurs at a portion where the adhesive force at the interface between the coating and the primary coating layer 3 is reduced, and water accumulates there and generates blisters. When blisters are generated at the interface between the bare optical fiber 2 and the primary coating 3, lateral pressure is applied to the bare optical fiber 2, resulting in an increase in microbend loss. Therefore, in order to improve the water resistance, it is necessary to increase the adhesion at the interface between the bare optical fiber 2 and the primary coating layer 3 to prevent water from entering the interface. [0009] The adhesive force between the bare optical fiber 2 and the primary coating layer 3 is set so as not to be peeled off even when immersed in water. In order to prevent the shape of the coating layer from being deformed when the layer is removed, the rigidity according to the adhesive force with the bare optical fiber 2 should be increased.
It is necessary to have. Regarding the improvement of the removability of the coating layer, JP-A-2000-111767 and JP-A-200
0-155248 and JP-A-2000-56191 are disclosed. However, these disclosed techniques are mainly for suppressing residue remaining after the removal of the coating layer, and are not techniques for suppressing the deformation of the coating layer due to tape thinning. [0010] The present invention has been made to solve the above-mentioned problems, and comprises a primary coating layer, a secondary coating layer, and a coloring layer provided on the outer periphery of a bare optical fiber. A plurality of optical fiber cores are arranged in parallel, and the optical fiber tape cores integrated by coating a collective coating layer thereon,
The sum of the product of the second moment of area and the Young's modulus of each of the primary coating layer, the secondary coating layer, the coloring layer, and the collective coating layer, the adhesion of the resin forming the primary coating layer to the bare optical fiber, and the tape core The present invention provides an optical fiber ribbon, wherein the product of the number of cores of the wire is expressed by the following equation (2) in an atmosphere of a heating temperature at the time of removing the covering layer of the tape. ## EQU2 ## Ep: Young's modulus (kgf / mm2) of the primary coating layer at the heating temperature at the time of removing the batch covering layer of the tape cores. Es: Young of the secondary coating layer at the heating temperature at the time of removing the batch covering layer of the tape cores. Rate (kgf / mm2) Ec: Young's modulus of the colored layer at the heating temperature at the time of removing the batch covering layer of the tape core wire (kgf / mm2) Er: of the batch covering layer at the heating temperature at the time of removing the batch covering layer of the tape core wire Young's modulus (kgf / mm2) Ip: Second moment of area of primary coating layer (mm4) Is: Second moment of area of secondary coating layer (mm4) Ic: Second moment of area of colored layer (mm4) Ir: Batch coating Second moment of area of layer (mm4) n: Number of cores of tape core wire Gp: Glass adhesion force of primary coating layer at heating temperature (kgf / mm) at the time of removing optical fiber tape core coating layer collectively (kgf / mm) Limits the physical properties of the coating layer and the structure of the coating layer to the above ranges. As a result, the stiffness of the coating layer at the heating temperature during the simultaneous removal of the coating layer is greater than the compressive stress due to the adhesion of the primary coating layer to the bare optical fiber, so the coating layer does not collapse and remains undisturbed. I do. Next, the present invention will be described with reference to embodiments. FIG. 4 shows a collective coating layer removing step which is an object of the present invention. In the figure, reference numeral 11 denotes a commercially available hot stripper (heating type coating layer removing device), in which a heater 13 is incorporated. In order to remove the covering layer from the end of the tape core wire 7 at a time, the end portion of the optical fiber tape core 7 is set in the hot stripper 11 for a predetermined length, and as shown in FIG. A cut is made in the batch coating layer 6 and the coating layer 8 with the blade 12 of FIG. Then heater part 1
3 for a certain period of time to reduce the adhesion between the bare optical fiber 2 and the primary coating layer 3, and after the adhesion is reduced, move the optical fiber ribbon 7 toward the other end as shown in FIG. Then, the batch covering layer 6 and the covering layer 8 are removed. FIG.
(C) shows a state in which the coating layer has been removed. When the covering layer is collectively removed from the end of the optical fiber ribbon 7, if the interface adhesion between the bare optical fiber 2 and the primary covering layer 3 is significantly higher than the rigidity of the covering layer, the bare optical fiber may be removed. Before the peeling proceeds at the interface between the wire 2 and the primary coating layer 3, the coating layer 8 is broken by the compressive stress applied from the blade portion. Therefore, generally, the operation of removing the coating layer of the optical fiber tape core wire 7 is performed by the bare optical fiber 2.
For example, in order to reduce the adhesion at the interface between the coating and the primary coating layer 3, the heating is performed at about 70 to 100 ° C. Therefore, the present inventors have found that the adhesive force of the resin forming the primary coating layer 3 to the bare optical fiber 2 and the Young's modulus and the coating thickness of each coating layer at the heating temperature at the time of the tape coating layer removing operation are light. The effect of the removal of the coating layer of the fiber ribbon on the shape of the coating layer was investigated. as a result,
If the adhesion force of the primary coating layer 3 to the bare optical fiber 2 at the coating layer removal temperature and the parameters using the Young's modulus and the second moment of area of each coating layer are limited to a certain range, the coating layers are removed at once. It has been found that coating collapse at the time can be suppressed. The present inventors adjusted the amounts and types of the urethane acrylate-based UV-curable oligomers and monomers to adjust the amounts of the primary coating layer 3, the secondary coating layer 4, the coloring layer 5 and the batch coating layer 6. An ultraviolet-curable (UV) resin was prepared, an optical fiber ribbon was prepared by a conventional method using the combinations shown in Table 1, and the relationship between the Young's modulus of each coating layer and a parameter using the second moment of area was examined. [Table 1] In this study, the adhesion of the resin forming the primary coating layer 3 to the bare optical fiber 2 was evaluated by a 90 ° peel test. That is, the resin for forming the primary coating layer 3 is coated on a quartz glass substrate to a thickness of 200 μm and then coated for 100 m.
The composition was cured by irradiating ultraviolet rays of J / cm 2. This sheet is cut out at a width of 1 cm, and 90 mm at 50 mm / min at room temperature.
The force at the time of pulling in the direction of ° and peeling was measured. Next, this measurement was performed in a thermostat heated to 90 ° C. In order to measure the Young's modulus of the resin for forming the primary coating layer, the resin for forming the primary coating layer is placed on a glass substrate.
After application of 0 μm, the sheet was irradiated with ultraviolet rays of 1000 mmJ / cm 2 to form a sheet. A 6 mm wide strip is cut out from this sheet, the distance between the marked lines is 25 mm, and the pulling speed is 1 mm / min.
The Young's modulus was measured from the stress at the time of 2.5% tensile strain in a 90 ° C. constant temperature bath. Further, in order to evaluate the coating layer removal property of the optical fiber ribbon, each optical fiber ribbon was subjected to a hot stripper (S218C manufactured by Furukawa Electric) 11 shown in FIG.
Was used to collectively remove the coating layer at a pulling speed of 50 mm / min, and it was tested whether or not the coating layer appeared in a pipe shape.
At this time, the temperature of the heating unit was 90 ° C. Generally, a buckling weight Wk when a buckling occurs when a weight is applied to a column is expressed by the following equation (3). [Equation 3] C: terminal modulus, E: Young's modulus, I: second moment of area, L: length of column Therefore, the buckling weight Wk ( t
total) is expressed as in Equation 4. (Equation 4) On the other hand, when the collective coating layer of the optical fiber ribbon is removed, the coating layer receives compressive stress. This compressive stress is considered to increase as the adhesion between the bare optical fiber 2 and the primary coating layer 3 increases. Therefore, the value obtained by dividing this Wk (total) by the product of the adhesion of the primary coating layer forming resin to the bare optical fiber and the number of bare optical fiber cores of the optical fiber ribbon is the buckling load and the optical fiber tape core. This is the ratio K of the compressive stress applied to the coating layer when the batch coating layer is removed. Therefore, as this value K is larger, the coating layer is less likely to collapse and is more likely to appear in a pipe shape. (Equation 5) Table 1 shows these Examples 1 to 3 and Comparative Examples 1 to
The evaluation results of No. 3 are also shown. As can be seen from Table 1,
The ratio K of the buckling load to the compressive stress applied to the coating layer when the coating layer of the optical fiber ribbon is removed at a time is 1.7 or more, that is, the physical properties of the resin forming each coating layer and the coating structure of the optical fiber ribbon. If the above expression 1 is satisfied, the buckling load is sufficiently larger than the total adhesive force between the bare optical fiber and the interface of the primary coating layer. A good optical fiber ribbon is obtained. According to the present invention, as is apparent from the above embodiment,
By selecting the physical properties of the resin forming each coating layer and the coating structure of the optical fiber ribbon so as to satisfy the expression 1, when the optical fiber ribbons are connected to each other, the coating layer starts from the core end portion. Can be collectively removed without deformation of the coating layer, and the connection work becomes extremely easy. In addition, even if the optical fiber cable is placed in a state where the optical fiber cable is flooded for a long time, the interface between the bare optical fiber 2 and the primary coating layer 3 is kept strong enough to prevent the interface from peeling off, and the connection work is easy. Thus, it is possible to design a coating layer, and to provide an optical fiber ribbon suitable for FTTH. According to the present invention, a plurality of colored optical fiber cores in which a primary coating layer, a secondary coating layer, and a coloring layer are provided on the outer periphery of the bare optical fiber as described above are provided in parallel. Side by side, the optical fiber tape core wire integrated by coating a batch coating layer thereon, the primary coating layer, the secondary coating layer, the coloring layer,
The product of the sum of the product of the second moment of area and Young's modulus of each collective coating layer, the product of the optical fiber bare wire adhesion of the primary coating material and the number of tape cores is determined by the heating temperature applied when removing the collective coating layer of the tape core wire. Since the relationship represented by the expression 1 is satisfied, it is possible to provide an optical fiber ribbon having good connectivity without coating collapse at the time of removing the tape collective coating layer.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an optical fiber core. FIG. 2 is a sectional view showing an optical fiber ribbon. FIG. 3 is an explanatory diagram showing a state in which a coating layer of an optical fiber ribbon is removed. FIG. 4 is an explanatory diagram showing an initial stage of a collective coating layer removing step of the optical fiber ribbon using a hot stripper. [Description of Signs] 1 Optical fiber core wire 2 Optical fiber bare wire 3 Primary coating layer 4 Secondary coating layer 5 Colored layer 6 Batch coating layer 7 Optical fiber tape core 8 Fiber coating layer 11 Hot stripper

Claims (1)

Claims: 1. A plurality of optical fiber cores comprising a primary coating layer, a secondary coating layer, and a coloring layer provided on the outer periphery of a bare optical fiber are arranged in parallel, and a collective coating layer is formed thereon. In the optical fiber ribbon, the primary coating layer, the secondary coating layer, the coloring layer, and the collective coating layer each have the sum of the product of the secondary moment of area and the Young's modulus and form the primary coating layer. An optical fiber tape characterized in that the product of the adhesion of the resin to the bare optical fiber and the number of cores of the tape core is expressed by the following equation (1) in an atmosphere at a heating temperature when the batch coating layer of the tape core is removed. Core wire [Equation 1] Ep: Young's modulus (kgf / mm2) of the primary coating layer at the heating temperature at the time of removing the batch covering layer of the tape core (Ef): Young's modulus (kgf / mm2) of the secondary coating layer at the heating temperature at the time of removing the batch covering layer of the tape core / mm2) Ec: Young's modulus of the colored layer at the heating temperature when removing the batch covering layer of the tape core (kgf / mm2) Er: Young's modulus of the batch covering layer at the heating temperature when removing the batch covering layer of the tape core ( kgf / mm2) Ip: Second moment of area of primary coating layer (mm4) Is: Second moment of area of secondary coating layer (mm4) Ic: Second moment of area of colored layer (mm4) Ir: Cross section of batch coating layer Second moment (mm4) n: Number of cores of tape core wire Gp: Glass adhesion force of primary coating layer at heating temperature at the time of removing optical fiber tape core batch coating layer (kgf / mm)