Optical fiber ribbon and method of manufacturing the same

Abstract

This suppresses an increase in transmission loss and ensures adhesive strength between optical fiber cores. [Solution] The device comprises a plurality of optical fiber cores and an adhesive resin that connects the plurality of optical fiber cores, and the adhesive resin has a viscosity greater than 35 mPa·S and less than 147 mPa·S in at least part of the temperature range from 50°C to 75°C before curing.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to optical fiber ribbons and methods for manufacturing optical fiber ribbons.

[0002] Conventionally, optical fiber ribbons including a plurality of optical fiber core wires have been developed. For example, Patent Document 1 discloses an intermittent optical fiber ribbon in which a plurality of optical fiber core wires are arranged in a parallel row, and in which connected portions and non-connected portions are intermittently formed between adjacent optical fiber core wires. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-228688 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the viscosity of the adhesive resin used to bond multiple optical fiber cores together is high when it is applied, the transmission loss of the optical fiber ribbon may increase due to factors such as the adhesive resin swelling up. On the other hand, if the viscosity of the adhesive resin when it is applied is low, the adhesive resin may spread thinly, resulting in a decrease in adhesive strength.

[0005] An object of the present disclosure is to provide an optical fiber ribbon and a method for manufacturing the optical fiber ribbon that can suppress an increase in transmission loss and ensure adhesive strength between the optical fiber core wires. [Means for solving the problem]

[0006] The optical fiber ribbon of the present disclosure comprises a plurality of optical fiber core wires and an adhesive resin that connects the plurality of optical fiber core wires, and the adhesive resin has a viscosity greater than 35 mPa·S and less than 147 mPa·S in at least a portion of the temperature range from 50°C to 75°C before curing. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to suppress an increase in transmission loss and ensure adhesive strength between optical fiber cores. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an optical fiber ribbon according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view of the optical fiber ribbon shown in FIG. [Figure 3] FIG. 3 is a graph showing the correspondence relationship between the temperature and viscosity of the adhesive resin shown in FIG. 1 for each content of the monomer in the adhesive resin. [Figure 4] FIG. 4 is a diagram showing an optical fiber ribbon according to a modified example of the first embodiment of the present disclosure. [Figure 5] FIG. 5 is a cross-sectional view of the optical fiber ribbon shown in FIG. [Figure 6] FIG. 6 is a diagram showing an optical fiber ribbon according to a second embodiment of the present disclosure. [Figure 7] FIG. 7 is a cross-sectional view of the optical fiber ribbon shown in FIG. [Figure 8] FIG. 8 is a diagram showing an optical fiber ribbon according to a modified example of the second embodiment of the present disclosure. [Figure 9] FIG. 9 is a diagram showing an optical fiber ribbon according to a third embodiment of the present disclosure. [Figure 10] FIG. 10 is a cross-sectional view of the optical fiber ribbon shown in FIG. [Figure 11] FIG. 11 is a diagram showing an optical fiber ribbon according to a fourth embodiment of the present disclosure. [Figure 12] FIG. 12 is a cross-sectional view of the optical fiber ribbon shown in FIG. [Figure 13] FIG. 13 is a diagram showing measurement results of the transmission loss and adhesive strength when the viscosity of the adhesive resin is changed for the optical fiber ribbons according to the first to fourth embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Description of Embodiments of the Present Disclosure> First, embodiments of the present disclosure will be listed and described. The optical fiber ribbon according to an embodiment of the present disclosure includes: (1) A cable comprising a plurality of optical fiber cores and an adhesive resin connecting the plurality of optical fiber cores, wherein the adhesive resin has a viscosity greater than 35 mPa·S and less than 147 mPa·S in at least a portion of the temperature range from 50°C to 75°C before hardening.

[0010] In this way, by applying an adhesive resin of appropriate viscosity, it is possible to prevent the adhesive resin from swelling up, thereby suppressing an increase in transmission loss in the optical fiber ribbon, and also to prevent the adhesive resin from spreading thinly, thereby ensuring the adhesive strength between the optical fiber core wires.

[0011] (2) In the optical fiber ribbon of (1) above, the adhesive resin may be a urethane acrylate ultraviolet curing resin containing 10 weight percent to 30 weight percent of a monomer.

[0012] With this configuration, the viscosity of the adhesive resin can be adjusted to be greater than 35 mPa·S and less than 147 mPa·S in at least a part of the temperature range from 50° C. to 75° C.

[0013] (3) In the optical fiber ribbon of (2) above, the monomer may be any one of isobornyl acrylate, N-vinyl caprolactam, 2-ethylhexyl acrylate, trimethylolpropane triacrylate, and acryloylmorpholine.

[0014] With this configuration, the viscosity of the adhesive resin can be adjusted effectively.

[0015] (4) In any one of the optical fiber ribbons (1) to (3) above, the adhesive resin may be intermittently applied to one of two parallel surfaces formed by arranging a plurality of the optical fiber core wires in parallel between adjacent optical fiber core wires.

[0016] With this configuration, an optical fiber ribbon in which adhesive resin is intermittently provided on one of the two parallel surfaces can be realized that suppresses increases in transmission loss and ensures adhesive strength between the optical fiber cores.

[0017] (5) In any one of the optical fiber ribbons (1) to (3) above, the optical fiber ribbon may include a plurality of sub-ribbons, each having two or more of the optical fiber core wires, and the adhesive resin may be intermittently applied between adjacent sub-ribbons on one of two parallel surfaces formed by arranging the sub-ribbons in parallel.

[0018] With this configuration, in an optical fiber ribbon in which adhesive resin is intermittently provided on one of the two parallel surfaces, it is possible to realize an optical fiber ribbon that suppresses an increase in transmission loss and ensures the adhesive strength between each of the optical fiber core wires in the sub-ribbons.

[0019] (6) In any one of the optical fiber ribbons (1) to (3) above, the adhesive resin may be continuously applied in a line shape so as to move back and forth in the width direction of one of the two parallel surfaces formed by arranging a plurality of the optical fiber core wires in parallel.

[0020] With this configuration, in an intermittent optical fiber ribbon in which adhesive resin is continuously applied in a line on one of two parallel surfaces formed by arranging multiple optical fiber cores in parallel, it is possible to realize an optical fiber ribbon that suppresses an increase in transmission loss and ensures the adhesive strength between the optical fiber cores.

[0021] (7) In any one of the optical fiber ribbons (1) to (3) above, the optical fiber ribbon may include a plurality of sub-ribbons, each having two or more of the optical fiber core wires, and the adhesive resin may be continuously applied in a line shape to one of two parallel surfaces formed by arranging the plurality of sub-ribbons in parallel, so as to move back and forth in the width direction of the parallel surface.

[0022] With this configuration, in an intermittent optical fiber ribbon consisting of multiple cores in which adhesive resin is continuously provided in a line on one of the two parallel surfaces, it is possible to realize an optical fiber ribbon that suppresses an increase in transmission loss and ensures the adhesive strength between each optical fiber core of the sub-ribbon.

[0023] (8) In any one of the optical fiber ribbons (1) to (3) above, the adhesive resin may be applied to the entirety of the plurality of optical fiber core wires, and the adhesive resin between adjacent optical fiber core wires may be intermittently removed.

[0024] With this configuration, an optical fiber ribbon can be realized in which adhesive resin is applied to the entire surface of multiple optical fiber cores and the adhesive resin between adjacent optical fiber cores is intermittently removed, thereby suppressing an increase in transmission loss and ensuring adhesive strength between the optical fiber cores.

[0025] (9) In the optical fiber ribbon of (4) above, the adhesive resin may be applied until it reaches the other of the two parallel surfaces.

[0026] With this configuration, in an optical fiber ribbon in which adhesive resin is intermittently provided from one parallel surface to the other parallel surface, it is possible to realize an optical fiber ribbon that suppresses an increase in transmission loss and ensures adhesive strength between the optical fiber cores.

[0027] A method for manufacturing an optical fiber ribbon according to an embodiment of the present disclosure includes: (10) A method for manufacturing an optical fiber ribbon having a plurality of optical fiber core wires, wherein an adhesive resin for connecting the plurality of optical fiber core wires is applied at a viscosity greater than 35 mPa·S and less than 147 mPa·S.

[0028] In this way, by applying an adhesive resin of appropriate viscosity, it is possible to prevent the adhesive resin from swelling up, thereby suppressing an increase in transmission loss in the optical fiber ribbon, and also to prevent the adhesive resin from spreading thinly, thereby ensuring the adhesive strength between the optical fiber core wires.

[0029] (11) In the manufacturing method of the optical fiber ribbon described above in (10), the adhesive resin may be intermittently applied to one of two parallel surfaces formed by arranging a plurality of the optical fiber core wires in parallel between adjacent optical fiber core wires.

[0030] By using this method, it is possible to manufacture an optical fiber ribbon in which adhesive resin is intermittently provided on one of the two parallel surfaces, while suppressing an increase in transmission loss and ensuring adhesive strength between the optical fiber core wires.

[0031] (12) In the manufacturing method of an optical fiber ribbon described above in (10), the optical fiber ribbon may include a plurality of sub-ribbons, each having two or more of the optical fiber core wires, and the adhesive resin may be intermittently applied between adjacent sub-ribbons on one of two parallel surfaces formed by arranging the sub-ribbons in parallel.

[0032] By using this method, it is possible to manufacture an optical fiber ribbon in which adhesive resin is intermittently provided on one of the two parallel surfaces, which suppresses an increase in transmission loss and ensures the adhesive strength between each optical fiber core wire of the sub-ribbon.

[0033] (13) In the manufacturing method of the optical fiber ribbon described above in (10), the adhesive resin may be continuously applied in a line shape to one of the two parallel surfaces formed by arranging a plurality of the optical fiber core wires in parallel, while being moved back and forth in the width direction of the parallel surface.

[0034] By using this method, it is possible to manufacture an intermittent optical fiber ribbon in which adhesive resin is continuously applied in a line on one of two parallel surfaces formed by arranging multiple optical fiber cores in parallel, while suppressing an increase in transmission loss and ensuring adhesive strength between the optical fiber cores.

[0035] (14) In the manufacturing method of an optical fiber ribbon described in (10) above, the optical fiber ribbon may include a plurality of sub-ribbons, each having two or more of the optical fiber core wires, and the adhesive resin may be continuously applied in a line shape to one of two parallel surfaces formed by arranging the plurality of sub-ribbons in parallel while being moved back and forth in the width direction of the parallel surface.

[0036] By using this method, it is possible to manufacture an intermittent optical fiber ribbon consisting of multiple cores, in which adhesive resin is continuously provided in a line on one of the two parallel surfaces, while suppressing an increase in transmission loss and ensuring the adhesive strength between each optical fiber core of the sub-ribbon.

[0037] (15) In the manufacturing method of the optical fiber ribbon described above in (10), the adhesive resin may be applied to the entirety of the plurality of optical fiber core wires, and the adhesive resin between the adjacent optical fiber core wires may be intermittently removed.

[0038] By using this method, an optical fiber ribbon can be manufactured in which adhesive resin is applied to the entire surface of multiple optical fiber cores and the adhesive resin between adjacent optical fiber cores is intermittently removed, thereby suppressing an increase in transmission loss and ensuring adhesive strength between the optical fiber cores.

[0039] (16) In the method for manufacturing an optical fiber ribbon according to (10) above, the adhesive resin may be applied until it reaches the other of the two parallel surfaces.

[0040] By using this method, it is possible to manufacture an optical fiber ribbon in which adhesive resin is intermittently applied from one parallel surface to the other parallel surface, while suppressing an increase in transmission loss and ensuring adhesive strength between the optical fiber cores.

[0041] <Details of the embodiment of the present disclosure> Specific examples of the optical fiber ribbon of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0042] [First embodiment] (Example 1) Fig. 1 is a diagram showing an optical fiber ribbon 100 according to a first embodiment of the present disclosure. Fig. 2 is a cross-sectional view of the optical fiber ribbon 100 shown in Fig. 1. More specifically, Fig. 2(A) is a cross-sectional view taken along line IIA-IIA shown in Fig. 1, Fig. 2(B) is a cross-sectional view taken along line IIB-IIB shown in Fig. 1, and Fig. 2(C) is a cross-sectional view taken along line IIC-IIC shown in Fig. 1.

[0043] 1 and 2, an optical fiber ribbon 100 includes a plurality of optical fiber core wires 10 arranged in parallel, and an adhesive resin 20 connecting the plurality of optical fiber core wires 10. In FIG. 1, as an example, the optical fiber ribbon 100 includes 12 optical fiber core wires 10. Hereinafter, the extension direction of the optical fiber core wires 10 is defined as the Y direction, and the direction in which the plurality of optical fiber core wires 10 are arranged, i.e., the width direction of the optical fiber ribbon 100, is defined as the X direction. Each optical fiber core wire 10 is, for example, a single core fiber (SCF (Single Core Fiber)).

[0044] The adhesive resin 20 is applied so as to intermittently connect adjacent coated optical fibers 10. For example, the adhesive resin 20 is applied intermittently using a dispenser to one of two parallel surfaces formed by arranging a plurality of coated optical fibers 10 side by side, between the outer peripheries of adjacent coated optical fibers 10, and then cured. The adhesive resin 20 is applied in a state where its viscosity is greater than 35 mPa·S and less than 147 mPa·S in at least a part of the temperature range from 50°C to 75°C before curing.

[0045] More specifically, adhesive resin 20 is a urethane acrylate ultraviolet curable resin, and by adding a monomer, its viscosity is adjusted to be greater than 35 mPa·S and less than 147 mPa·S in at least a part of the temperature range from 50°C to 75°C. The monomer contained in adhesive resin 20 is isobornyl acrylate, N-vinyl caprolactam, 2-ethylhexyl acrylate, trimethylolpropane triacrylate, acryloylmorpholine, or the like.

[0046] Fig. 3 is a graph showing the correspondence relationship between the temperature and viscosity of the adhesive resin 20 shown in Fig. 1 for each content of monomer in the adhesive resin 20. The vertical axis of the graph shown in Fig. 3 represents viscosity, and the horizontal axis represents temperature. This graph shows the relationship between the temperature and viscosity of the adhesive resin 20 when the content of monomer in the adhesive resin 20 is 0 wt%, 10 wt%, 20 wt%, and 30 wt%.

[0047] 3, the viscosity of the adhesive resin 20 tends to decrease as the monomer content in the adhesive resin 20 increases. When the monomer content is in the range of 10% by weight to 30% by weight, the viscosity of the adhesive resin 20 can be easily adjusted to a range greater than 35 mPa·S and less than 147 mPa·S in at least a portion of the temperature range from 50°C to 75°C. Therefore, it is preferable that the monomer content of the adhesive resin 20 be adjusted to be greater than or equal to 10% by weight and less than or equal to 30% by weight.

[0048] (Example 2) Fig. 4 is a diagram showing an optical fiber ribbon 200 according to a modified example of the first embodiment of the present disclosure. Fig. 5 is a cross-sectional view of the optical fiber ribbon 200 shown in Fig. 4. More specifically, Fig. 5(A) is a cross-sectional view taken along line VA-VA shown in Fig. 4, Fig. 5(B) is a cross-sectional view taken along line VB-VB shown in Fig. 4, and Fig. 5(C) is a cross-sectional view taken along line VC-VC shown in Fig. 4.

[0049] 4 and 5, the optical fiber ribbon 200 includes a plurality of sub-ribbons 231, each having two optical fibers 210. Adjacent optical fibers 210 included in a sub-ribbon 231 are connected to each other over their entire length. The optical fiber ribbon 200 shown in FIG. 4 includes, as an example, six sub-ribbons 231, which are arranged along the width direction (the X direction shown in FIG. 4).

[0050] The number of optical fiber cores 210 included in each of the sub-ribbons 231 is not limited to two, but may be three or more.

[0051] Furthermore, optical fiber ribbon 200 includes adhesive resin 220 that connects adjacent sub-ribbons 231. More specifically, adhesive resin 220 is applied intermittently between multiple sub-ribbons 231 on one of two parallel surfaces formed by arranging multiple sub-ribbons 231 in parallel.

[0052] The adhesive resin 20 is formed from a composition similar to that of the adhesive resin 20 shown in FIG. 1, and is applied using a dispenser or the like in a state in which the viscosity is greater than 35 mPa·S and less than 147 mPa·S in at least a portion of the temperature range from 50°C to 75°C before curing.

[0053] [Second embodiment] (Example 1) Fig. 6 is a diagram showing an optical fiber ribbon 300 according to a second embodiment of the present disclosure. Fig. 7 is a cross-sectional view of the optical fiber ribbon 300 shown in Fig. 6. More specifically, Fig. 7(A) is a cross-sectional view taken along line VIIA-VIIA shown in Fig. 6, Fig. 7(B) is a cross-sectional view taken along line VIIB-VIIB shown in Fig. 6, and Fig. 7(C) is a cross-sectional view taken along line VIIC-VIIC shown in Fig. 6.

[0054] Referring to Figures 6 and 7, the optical fiber ribbon 300, similar to the optical fiber ribbon 100 shown in Figure 1, comprises a plurality of parallel-arranged optical fiber core wires 310 and an adhesive resin 320 connecting these plurality of optical fiber core wires 310.

[0055] The adhesive resin 320 is continuously applied in a line shape so as to reciprocate in the width direction (X direction shown in Fig. 6) of one of two parallel surfaces formed by arranging a plurality of optical fiber cores 310 in parallel. The adhesive resin 320 is formed from the same composition as the adhesive resin 20 shown in Fig. 1, and is applied using a dispenser or the like in a state where the viscosity is greater than 35 mPa·S and less than 147 mPa·S in at least a part of the temperature range from 50°C to 75°C before curing.

[0056] (Example 2) Fig. 8 is a diagram showing an optical fiber ribbon 400 according to a modified example of the second embodiment of the present disclosure. The optical fiber ribbon 400 includes a plurality of sub-ribbons 411, each having two optical fibers 410. Adjacent optical fibers 410 included in a sub-ribbon 411 are connected to each other over their entire lengths. The optical fiber ribbon 400 shown in Fig. 8 includes, as an example, six sub-ribbons 411, which are arranged along the width direction (the X direction shown in Fig. 8).

[0057] The number of optical fiber cores 410 included in each of the sub-ribbons 411 is not limited to two, but may be three or more.

[0058] Optical fiber ribbon 400 also includes adhesive resin 420 that connects adjacent sub-ribbons 411. Adhesive resin 420 is continuously applied in a line shape to one of two parallel surfaces formed by arranging multiple sub-ribbons 411 in parallel, so that adhesive resin 420 moves back and forth across the width direction of the parallel surface (X direction shown in FIG. 8). Adhesive resin 420 is made of the same composition as adhesive resin 20 shown in FIG. 1, and is applied using a dispenser or the like in a state where its viscosity is greater than 35 mPa·S and less than 147 mPa·S in at least a portion of the temperature range of 50°C to 75°C before curing.

[0059] [Third embodiment] Fig. 9 is a diagram showing an optical fiber ribbon 500 according to a third embodiment of the present disclosure. Fig. 10 is a cross-sectional view of the optical fiber ribbon 500 shown in Fig. 9. More specifically, Fig. 10(A) is a cross-sectional view taken along line XA-XA shown in Fig. 9, Fig. 10(B) is a cross-sectional view taken along line XB-XB shown in Fig. 9, and Fig. 10(C) is a cross-sectional view taken along line XC-XC shown in Fig. 9.

[0060] 9 and 10, the optical fiber ribbon 500, similar to the optical fiber ribbon 100 shown in FIG. 1, comprises a plurality of parallel-arranged optical fiber core wires 510 and an adhesive resin 520 connecting these plurality of optical fiber core wires 510.

[0061] The adhesive resin 520 is applied to the entirety of the multiple optical fiber cores 510, and then intermittently removed in the portions between adjacent optical fiber cores 510 along the Y direction, which is the extension direction of the optical fiber cores 510, to form slit portions 521. The adhesive resin 520 is made of the same composition as the adhesive resin 20 shown in Fig. 1, and is applied in a state where its viscosity is greater than 35 mPa·S and less than 147 mPa·S in at least a part of the temperature range from 50°C to 75°C before curing.

[0062] [Fourth embodiment] Fig. 11 is a diagram showing an optical fiber ribbon 600 according to a fourth embodiment of the present disclosure. Fig. 12 is a cross-sectional view of the optical fiber ribbon 600 shown in Fig. 11. More specifically, Fig. 12(A) is a cross-sectional view taken along line XIIA-XIIA shown in Fig. 11, Fig. 12(B) is a cross-sectional view taken along line XIIB-XIIB shown in Fig. 11, and Fig. 12(C) is a cross-sectional view taken along line XIIC-XIIC shown in Fig. 11.

[0063] Referring to Figures 11 and 12, the optical fiber ribbon 600, similar to the optical fiber ribbon 100 shown in Figure 1, comprises a plurality of parallel-arranged optical fiber core wires 610 and an adhesive resin 620 connecting these plurality of optical fiber core wires 610.

[0064] The adhesive resin 620 is applied so as to intermittently connect adjacent coated optical fibers 610. As described above, the adhesive resin 20 (see FIG. 1) of the optical fiber ribbon 100 according to the first embodiment is applied intermittently to one of the two parallel surfaces formed by arranging a plurality of coated optical fibers 10 in parallel. In contrast, the adhesive resin 620 of the optical fiber ribbon 600 is applied until it reaches the other of the two parallel surfaces formed by arranging a plurality of coated optical fibers 610 in parallel, as shown in FIGS. 12(A) and 12(C).

[0065] 11, one of the multiple optical fiber cores 610 is designated as a first optical fiber core 610A, and the optical fiber core 610 adjacent to the first optical fiber core 610A is designated as a second optical fiber core 610B. Also, the optical fiber core 610 adjacent to the second optical fiber core 610B and different from the first optical fiber core 610A is designated as a third optical fiber core 610C, and the optical fiber core 610 adjacent to the third optical fiber core 610C and different from the second optical fiber core 610B is designated as a fourth optical fiber core 610D.

[0066] Furthermore, the adhesive resin 620 connecting the first optical fiber core 610A and the second optical fiber core 610B is referred to as the first adhesive resin 620A, the adhesive resin 620 connecting the second optical fiber core 610B and the third optical fiber core 610C is referred to as the second adhesive resin 620B, and the adhesive resin 620 connecting the third optical fiber core 610C and the fourth optical fiber core 610D is referred to as the third adhesive resin 620C.

[0067] In this case, in the Y direction, which is the extending direction of the optical fiber core 610, the first adhesive resin 620A, the second adhesive resin 620B, and the third adhesive resin 620C are applied at different positions from one another.

[0068] Furthermore, adhesive resin 620, which includes first adhesive resin 620A, second adhesive resin 620B, and third adhesive resin 620C, is formed from a composition similar to adhesive resin 20 shown in FIG. 1, and is applied with a viscosity greater than 35 mPa·S and less than 147 mPa·S in at least a portion of the temperature range from 50°C to 75°C before curing.

[0069] [Experimental results for transmission loss and adhesive strength] 13 is a diagram showing measurement results of transmission loss and adhesive strength when the viscosity of the adhesive resin is changed for the optical fiber ribbons 200, 300, 500, and 600 according to the first to fourth embodiments. Here, the measurement results of transmission loss and adhesive strength when the viscosity of the adhesive resin is changed in the temperature range of 50°C to 75°C before curing will be described for the optical fiber ribbon 200 according to the first embodiment, the optical fiber ribbon 300 according to the second embodiment, the optical fiber ribbon 500 according to the third embodiment, and the optical fiber ribbon 600 according to the fourth embodiment.

[0070] Each of the optical fiber ribbons 200, 300, 500, and 600 has 12 coated optical fibers 210, 310, 510, and 610. The transmission loss per kilometer of each of the optical fiber ribbons 200, 300, 500, and 600 wound on a bobbin was measured. In the table shown in Fig. 13, a transmission loss value of less than 0.25 dB is assigned an A, and a transmission loss value of 0.25 dB or greater is assigned a C.

[0071] As shown in Figure 13, for all of the optical fiber ribbons 200, 300, 500, and 600, when the viscosity of the adhesive resin was in the range of 35 mPa·S to 115 mPa·S, the transmission loss value was less than 0.25 dB. On the other hand, for all of the optical fiber ribbons 200, 300, 500, and 600, when the viscosity of the adhesive resin was 147 mPa·S, the transmission loss value was 0.25 dB or more. These results show that in order to suppress an increase in the transmission loss of the optical fiber ribbons 200, 300, 500, and 600, it is better for the viscosity of the adhesive resin to be lower than 147 mPa·S.

[0072] Furthermore, the adhesive strength between the optical fibers in the optical fiber ribbons 200, 300, 500, and 600 was measured. Here, for each of the optical fiber ribbons 200, 300, 500, and 600, two optical fibers connected by adhesive resin were held and torn at a speed of 200 mm / min, and the load was measured. In the table shown in Fig. 13, when the load was 0.025 N or more, it was rated A, and when the load was less than 0.025 N, it was rated C.

[0073] As shown in Figure 13, for all of optical fiber ribbons 200, 300, 500, and 600, when the viscosity of the adhesive resin was in the range of 52 mPa·S to 147 mPa·S, the load was 0.025 N or more, and the adhesive strength was high. On the other hand, for all of optical fiber ribbons 200, 300, 500, and 600, when the viscosity of the adhesive resin was 35 mPa·S, the load was less than 0.025 N, and the adhesive strength was low. From these results, it can be seen that in order to ensure the adhesive strength between the optical fibers in optical fiber ribbons 200, 300, 500, and 600, it is better for the viscosity of the adhesive resin to be higher than 35 mPa·S.

[0074] The above measurement results show that in order to suppress an increase in transmission loss in the optical fiber ribbons 200, 300, 500, and 600 and ensure the adhesive strength between the optical fibers, it is better for the viscosity of the adhesive resin to be higher than 35 mPa·S and lower than 147 mPa·S. That is, in any of the optical fiber ribbons according to the first to fourth embodiments described above, if the viscosity of the adhesive resin is higher than 35 mPa·S and lower than 147 mPa·S in at least a part of the temperature range of 50°C to 75°C before curing, it is possible to more reliably suppress an increase in transmission loss in the optical fiber ribbon and ensure the adhesive strength between the optical fibers.

[0075] Although the present disclosure has been described above based on specific embodiments, the present invention is not limited to these examples, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. [Explanation of symbols]

[0076] 10,210,310,410,510,610 optical fiber core 20,220,320,420,520,620 Adhesive resin 100, 200, 300, 400, 500, 600 optical fiber ribbon 231,411 Sub-ribbons 521 Slit section 610A First Optical Fiber 610B Second Optical Fiber 610C Third Optical Fiber 610D 4th optical fiber core 620A 1st adhesive resin 620B 2nd adhesive resin 620C 3rd adhesive resin

Claims

1. A plurality of optical fiber cores; an adhesive resin that connects the plurality of optical fiber cores, The adhesive resin has a viscosity greater than 35 mPa·S and less than 147 mPa·S in at least a portion of the temperature range of 50°C to 75°C before curing.

2. 2. The optical fiber ribbon according to claim 1, wherein the adhesive resin is a urethane acrylate ultraviolet curable resin containing 10 weight percent to 30 weight percent of a monomer.

3. 3. The optical fiber ribbon according to claim 2, wherein the monomer is any one of isobornyl acrylate, N-vinyl caprolactam, 2-ethylhexyl acrylate, trimethylolpropane triacrylate, and acryloylmorpholine.

4. An optical fiber ribbon as described in any one of claims 1 to 3, wherein the adhesive resin is intermittently applied to one of two parallel surfaces formed by arranging a plurality of the optical fiber core wires in parallel between adjacent optical fiber core wires.

5. The optical fiber ribbon includes a plurality of sub-ribbons, each of which has two or more of the optical fiber core wires, 4. The optical fiber ribbon according to claim 1, wherein the adhesive resin is intermittently applied between adjacent sub-ribbons on one of two parallel surfaces formed by arranging the sub-ribbons in parallel.

6. An optical fiber ribbon as described in any one of claims 1 to 3, wherein the adhesive resin is continuously applied in a line shape so as to move back and forth in the width direction of one of two parallel surfaces formed by arranging a plurality of the optical fiber core wires in parallel.

7. The optical fiber ribbon includes a plurality of sub-ribbons, each of which has two or more of the optical fiber core wires, An optical fiber ribbon as described in any one of claims 1 to 3, wherein the adhesive resin is continuously applied in a line shape so as to move back and forth in the width direction of one of the two parallel surfaces formed by arranging the multiple sub-ribbons in parallel.

8. the adhesive resin is applied to the entirety of the plurality of optical fiber cores, 4. The optical fiber ribbon according to claim 1, wherein the adhesive resin between adjacent optical fibers is intermittently removed.

9. 5. The optical fiber ribbon according to claim 4, wherein the adhesive resin is applied until it reaches the other of the two parallel surfaces.

10. A method for manufacturing an optical fiber ribbon having a plurality of optical fiber core wires, The method for manufacturing an optical fiber ribbon includes applying an adhesive resin for connecting the plurality of coated optical fibers with a viscosity of more than 35 mPa·S and less than 147 mPa·S.

11. The method for manufacturing an optical fiber ribbon according to claim 10, wherein the adhesive resin is intermittently applied to one of two parallel surfaces formed by arranging a plurality of the optical fiber core wires in parallel between adjacent optical fiber core wires.

12. The optical fiber ribbon includes a plurality of sub-ribbons, each of which has two or more of the optical fiber core wires, The method for manufacturing an optical fiber ribbon according to claim 10, wherein the adhesive resin is intermittently applied between adjacent sub-ribbons on one of two parallel surfaces formed by arranging the sub-ribbons in parallel.

13. A method for manufacturing an optical fiber ribbon as described in claim 10, wherein the adhesive resin is continuously applied in a line shape to one of two parallel surfaces formed by arranging a plurality of the optical fiber core wires in parallel, while being moved back and forth in the width direction of the parallel surface.

14. The optical fiber ribbon includes a plurality of sub-ribbons, each of which has two or more of the optical fiber core wires, The method for manufacturing an optical fiber ribbon according to claim 10, wherein the adhesive resin is continuously applied in a line shape to one of two parallel surfaces formed by arranging the plurality of sub-ribbons in parallel while moving back and forth in the width direction of the parallel surface.

15. Applying the adhesive resin to the entirety of the plurality of optical fiber cores; The method for manufacturing an optical fiber ribbon according to claim 10, wherein the adhesive resin between adjacent optical fibers is intermittently removed.

16. The method for manufacturing an optical fiber ribbon according to claim 11, wherein the adhesive resin is applied until it reaches the other of the two parallel surfaces.

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