Anti-bending optical fiber ribbon and preparation method thereof, and optical cable

Abstract

The present application discloses a bend-resistant optical fiber ribbon, a preparation method thereof, and an optical cable, and relates to the field of optical information. The bend-resistant optical fiber ribbon includes: an optical fiber assembly, a first protective layer, and a second protective layer, which are arranged in sequence from the inside to the outside. The first protective layer is wrapped around the periphery of the optical fiber assembly, and the second protective layer is wrapped around the periphery of the first protective layer, wherein the ratio of the modulus of the second protective layer to the modulus of the first protective layer is (1.15 to 1.5): 1. Through the stress absorption and buffering of the inner and outer protective layers, the force on the optical fiber is reduced when the optical cable is bent, the bending resistance of the optical fiber is improved, the additional attenuation is reduced, the transmission performance is improved, and the signal stability is ensured. The second protective layer has a large modulus and is not prone to loose ribbons, ensuring the flatness and stability of the optical fiber ribbon and improving the success rate of optical fiber ribbon fusion. The first protective layer has a small modulus, which provides stress absorption and buffering for the optical fiber and reduces the damage to the optical fiber when the optical cable is bent.

Description

Technical Field

[0001] The present application relates to the field of optical information technology, and in particular to a bend-resistant optical fiber ribbon, a preparation method thereof, and an optical cable. Background Art

[0002] With the rapid development and increasing adoption of 5G technology, the communications industry is facing unprecedented opportunities and challenges. This not only significantly increases data transmission speeds and volumes, but also fosters innovation and application in cutting-edge fields like artificial intelligence and AI. This also places higher demands on outdoor optical cables, requiring higher fiber density and more convenient installation. Traditional stranded optical cables have a limited number of fiber cores, and during installation, each fiber must be individually spliced, which is time-consuming and labor-intensive.

[0003] Ribbon optical cable is a representative example of high-fiber-density optical cable. Its basic optical unit is a fiber ribbon, each of which can be made up of 4 to 24 optical fibers, depending on demand. Multiple fiber ribbons can be placed within a loose tube, and the cable is composed of one or more loose tubes, which exponentially increases the number of optical fibers. Compared to traditional loose tubes, which only contain 12 fibers, ribbon optical cable solves the problems of a small number of fibers and low fiber density. Because the basic optical unit is a fiber ribbon composed of multiple optical fibers, it is not necessary to fuse each fiber individually; only the ribbons need to be welded, saving construction time. Therefore, research on ribbon optical cables has become the primary approach used in the industry to increase fiber density and meet the needs of large-scale data transmission.

[0004] However, stress is transferred from the outside through the ribbon cable sheath to the loose tube and then to the optical fiber ribbon, which increases the additional loss of the optical fiber and affects the transmission performance. Summary of the Invention

[0005] The present application provides a bend-resistant optical fiber ribbon and a preparation method thereof, and an optical cable to solve the problem of large additional loss of existing optical fibers.

[0006] In a first aspect, the present application provides a bend-resistant optical fiber ribbon, comprising:

[0007] fiber optic components;

[0008] A first protective layer wrapped around the outer periphery of the optical fiber assembly; and

[0009] a second protective layer, wrapped around the outer periphery of the first protective layer;

[0010] The ratio of the modulus of the second protective layer to the modulus of the first protective layer is (1.15-1.5):1.

[0011] The present application reduces the stress on the optical fiber when the optical cable is bent, improves the bending resistance of the optical fiber, reduces additional attenuation, improves the transmission performance, and ensures signal stability through stress absorption and buffering of the inner and outer protective layers. The second protective layer has a large modulus and is less likely to have loose ribbons, ensuring the flatness and stability of the optical fiber ribbon and improving the success rate of optical fiber ribbon fusion. The first protective layer has a small modulus, providing stress absorption and buffering for the optical fiber, reducing damage to the optical fiber when the optical cable is bent. The ratio of the modulus of the second protective layer to the modulus of the first protective layer is (1.15 to 1.5): 1, so that during construction or use, when the stress of the bending of the optical cable is transmitted to the optical fiber ribbon through the loose tube, the second protective layer can mechanically protect the entire optical fiber ribbon, blocking part of the stress from continuing to be transmitted to the first protective layer and the optical fiber. The first protective layer can absorb and buffer the remaining stress, further reducing the impact of stress on the optical fiber and reducing optical fiber damage and attenuation.

[0012] In some embodiments, the modulus of the first protective layer is 300-350 MPa. The modulus of the first protective layer within this range can provide stress absorption and buffering for the optical fiber, reducing damage to the optical fiber when the optical cable is bent; and / or,

[0013] The modulus of the second protective layer is 400-450 MPa. The modulus of the second protective layer is within this range, which can stabilize the flatness of the optical fiber ribbon and improve the success rate of optical fiber ribbon fusion.

[0014] In some embodiments, the ratio of the elongation of the first protective layer to the elongation of the second protective layer is 1:(0.6-0.8). When the ratio of the elongation of the first protective layer to the elongation of the second protective layer is within this range, the effect of stress on the optical fiber can be reduced when the optical fiber ribbon is bent; and / or,

[0015] The elongation of the first protective layer is 20% to 30%. When the elongation of the first protective layer is within this range, the effect of the first protective layer on the bending of the optical fiber can be reduced when the optical cable is bent, thereby reducing stress concentration on the optical fiber; and / or,

[0016] The elongation of the second protective layer is 10% to 20%. When the elongation of the second protective layer is within this range, the first protective layer and the optical fiber will not be excessively bent, thereby reducing the attenuation of the optical fiber.

[0017] In some embodiments, the material of the first protective layer includes at least one of acrylic resins, epoxy resins, and vinyl ethers. The first protective layer using at least one of the above materials can provide stress absorption and buffering for the optical fiber; and / or,

[0018] The material of the second protective layer also includes at least one of acrylic resins, epoxy resins and vinyl ethers. The second protective layer uses at least one of the above materials to provide mechanical protection for the first protective layer and the optical fiber, thereby improving the bending resistance of the optical fiber.

[0019] It should be noted that the thickness of the first protective layer and the second protective layer may be equal or unequal, and may be 1.5 to 2.5 mm.

[0020] In some embodiments, the optical fiber assembly includes multiple optical units arranged side by side, each of which includes an optical fiber and a third protective layer arranged sequentially from the inside out, the third protective layer including a colored layer, and the colored layers of the multiple optical units each having a unique color. A common method for distinguishing optical fiber ribbons within the same loose tube is to use an inkjet printer to print characters on the surfaces of different optical fiber ribbons. However, the printing effect is affected by the inkjet printer, the properties of the printing ink, and the production speed, resulting in poor printing and difficulty in distinguishing optical fiber ribbons. By providing a colored layer on the third protective layer, the present application can distinguish different optical fibers by different colors, thereby facilitating optical fiber positioning.

[0021] In a second aspect, the present application provides a method for preparing a bend-resistant optical fiber ribbon, which is used to prepare the bend-resistant optical fiber ribbon of the first aspect, comprising the following steps:

[0022] Coating a first protective layer material on the outer surface of the optical fiber assembly, coating a second protective layer material on the outer surface of the first protective layer, and forming a first protective layer and a second protective layer respectively after curing;

[0023] Winding to form a bending-resistant optical fiber ribbon;

[0024] The coating pressure when coating the material of the first protective layer is smaller than the coating pressure when coating the material of the second protective layer.

[0025] The coating pressure when applying the material for the first protective layer is lower than the coating pressure when applying the material for the second protective layer. This allows for control of the modulus of the first and second protective layers, resulting in a greater modulus for the second protective layer than for the first. The high modulus of the second protective layer reduces ribbon loosening, ensures stable flatness of the optical fiber ribbon, and improves the success rate of fiber fusion splicing. The low modulus of the first protective layer provides stress absorption and buffering for the optical fiber, reducing damage to the optical fiber when the optical cable is bent. The inner and outer protective layer materials are coated and cured in a single step, eliminating the need for separate curing of the inner and outer layers. Only a single mold and curing unit are required, improving production efficiency and reducing costs.

[0026] It's important to note that the relationship between coating pressure and modulus is: pressure = modulus * strain, which primarily reflects changes in the mechanical properties of the resin during the coating process. Excessive pressure can lead to other problems, such as damage to the resin's microstructure and stress concentration. Excessive pressure can cause slippage between the resin and the optical fiber, resulting in uneven coating.

[0027] The viscosity of the material of the first protective layer at 25°C is 2500-3500 MPa·s, and the viscosity of the material of the second protective layer at 25°C is 4500-5500 MPa·s. Within this viscosity range, it is easy to control the coating pressure during coating and improve the bending resistance. The ratio of the needle penetration of the material of the first protective layer to the needle penetration of the material of the second protective layer is 1:(0.6-0.8). Within this range, the fluidity of the first protective layer can be higher than that of the second protective layer. Among them, the needle penetration (150g) of the material of the first protective layer is 350-450 (1 / 10mm). Within this range, the coating pressure of the first protective layer can be 90-110 bar, reducing the stress of the resin on the optical fiber and avoiding excessive attenuation during the production process. The needle penetration (150g) of the material of the second protective layer is 250-350 (1 / 10mm). Within this range, the coating pressure of the second protective layer can be 140-160 bar, thereby improving the covering force on the first protective layer and the optical fiber and obtaining a better thermal stripping effect.

[0028] Double-layer co-extrusion can be used to simultaneously coat the inner and outer resin layers on the fiber ribbon surface. The mold consists of an inner and outer mold. The optical fiber enters the mold through the first hole in the outer mold, filling the first cavity formed by the inner and outer molds. The outer resin enters through the second hole in the outer mold, filling the second cavity. Under the same pressure, the inner and outer resins flow through the first and second outlets along the direction of travel of the fiber ribbon, coating the optical fiber surface.

[0029] In some embodiments, the coating pressure ratio of the material coating the first protective layer to the material coating the second protective layer is 1:(1.8-2.7). When the coating pressure ratio of the material coating the first protective layer to the material coating the second protective layer is within this range, the pressure of the first protective layer on the optical fiber can be reduced, the attenuation exceeding the standard during the production process can be reduced, and the coating force of the second protective layer on the first protective layer and the optical fiber can be increased, thereby achieving a better thermal stripping effect; and / or,

[0030] The coating pressure when applying the material of the first protective layer is 90 to 110 bar. When the coating pressure when applying the material of the first protective layer is within this range, the modulus of the first protective layer can be controlled within the range of 300 to 350 MPa, with good elasticity and resistance to microbending and macrobending; and / or,

[0031] The coating pressure when coating the material of the second protective layer is 140 to 160 bar. When the coating pressure when coating the material of the second protective layer is within this range, the modulus of the second protective layer can be controlled within the range of 400 to 450 MPa, which has a large modulus and high mechanical strength; and / or,

[0032] The ratio of the power of the ultraviolet light to the curing degree when forming the first protective layer to the ratio of the power of the ultraviolet light to the curing degree when forming the second protective layer is 1:(0.7-0.9). When the ratio of the power of the ultraviolet light to the curing degree when forming the first protective layer to the ratio of the power of the ultraviolet light to the curing degree when forming the second protective layer is within this range, the curing degree of the second protective layer can be higher than that of the first protective layer, the ability of the second protective layer to resist external stress is improved, and the first protective layer can also improve its ability to absorb and buffer stress; and / or,

[0033] When curing to form the first protective layer, the ratio of the power of the ultraviolet light to the curing degree is 1300 to 1500; and / or,

[0034] When the second protective layer is cured, the ratio of the power of the ultraviolet light to the curing degree is 1000-1200.

[0035] Air pressure is applied to the coating material tank, pushing the coating material toward the mold, ensuring uniform and thorough coating of the coating resin onto the optical fiber surface. The inner and outer layer resins can be stored in separate tanks and applied simultaneously using a sandwich mold. To achieve excellent bending resistance, the outer layer's coating strength must be increased. Therefore, the coating pressure of the second protective layer must be higher than that of the first. This also minimizes stress on the optical fiber due to the first layer.

[0036] To ensure that both the inner and outer layers of resin have good fluidity, the mold temperature is set to 35-45°C, consistent with the temperature of the curing oven, to reduce the temperature fluctuation of the optical fiber. After coating, it enters the curing oven smoothly to improve the bending resistance.

[0037] UV light curing is used to cure the inner and outer resin layers from a fluid to a solid. After passing through the outer layer, the UV light intensity is partially attenuated by the time it reaches the inner layer. The ratio of UV light power to curing degree reflects the UV light intensity. Conventional optical fiber has a UV light power to curing degree ratio of 1800 to 2000. By controlling this ratio during the first protective layer, the stress on the optical fiber can be reduced. By controlling the ratio during the second protective layer, the strength of the second protective layer can be increased, ensuring stable flatness and improving the success rate of fiber ribbon fusion. The UV light power to curing degree ratio during the formation of the first protective layer is greater than the ratio during the formation of the second protective layer, ensuring a higher curing degree for the second protective layer.

[0038] Since the resin is divided into two layers, inner and outer layers, curing needs to be carried out in an oxygen-free environment. The nitrogen flow rate in the curing furnace is set to 35-45L / min to improve the curing efficiency.

[0039] In some embodiments, the coating of the material of the first protective layer on the outer surface of the optical fiber assembly, before curing to form the first protective layer, includes:

[0040] Laying out multiple optical units and arranging them in parallel to form an optical fiber assembly;

[0041] When paying out the line, the pay-out tension of the two outer light units is smaller than the pay-out tension of the other light units in the middle position.

[0042] When the two optical fibers at the edge enter the mold, they are subject to friction from the upper and lower edges of the mold entrance, as well as the side edges of the mold entrance. The remaining optical fibers are subject only to friction from the upper and lower edges of the mold. To maintain consistent friction between each optical fiber, the payout tension of the two optical fibers at the edge is lower than that of the remaining fibers. This compensates for the side friction of the mold on the two optical fibers. This ensures consistent length for each optical fiber, maintains excellent flatness, and aligns the optical fibers at the edge with the others. When the ribbon bends, the force applied to each optical fiber is dispersed and essentially uniform, achieving bending resistance.

[0043] In some embodiments, the pay-off tension of the two outer light units is 0.4N to 0.45N; and / or,

[0044] The pay-off tension of the intermediate position optical unit is 0.5N to 0.55N; and / or,

[0045] The take-up tension is 1.9N to 2.0N; and / or,

[0046] The wire pitch of the take-up wire is 3.6mm to 3.8mm; and / or,

[0047] The take-up speed is 350m / min~450m / min.

[0048] Taking a 12-core fiber ribbon as an example, 12 optical units of different colors are fixed to a separate payout frame. The two optical units at the edge of the ribbon (the first and 12th) are paid out with a tension of 0.4N to 0.45N, while the remaining optical units are paid out with a tension of 0.5N to 0.55N. All fibers are then gathered at the entrance of the coating die. This ensures that each optical unit is of uniform length, the ribbon is perfectly flat, and the optical units at the edge are aligned with the others. When the ribbon bends, the force applied to each optical unit is dispersed and essentially uniform, achieving bending resistance.

[0049] It should be noted that during the payout phase, the optical unit's surface becomes charged and attracts dust after experiencing rolling friction from the steering guide wheel and sliding friction from the fiber positioning rod. This affects the flatness of the fiber ribbon, reduces its bending resistance, and causes dust accumulation, which increases the stress on the fiber. This application adds an ion blower to remove the charge and dust from the fiber surface.

[0050] Setting up an ion blower can remove static electricity on the surface of the optical fiber. However, the ion blower will cause the optical fiber to shake, which will affect the flatness of the optical fiber ribbon, thereby reducing the bending resistance of the optical fiber ribbon. By placing the ion blower between the optical fiber pay-off and the coating resin, 100mm above the optical fiber, with the air outlet facing the optical fiber, and the air supply pressure being 0.15MPa, the static electricity on the surface of the optical fiber after treatment by the ion blower is 0kV, the static electricity removal effect is good, and the optical fiber has no obvious shaking, thereby improving the bending resistance.

[0051] The cured fiber optic ribbon is pulled along a crawler belt and finally wound onto a reel on a take-up frame. Compared to existing conventional resin fiber optic ribbons, the second protective layer of this bend-resistant fiber optic ribbon has a higher degree of cure and a smoother surface. To prevent slipping caused by the low friction between the two layers, the take-up tension and the cable arrangement pitch are increased to reduce bending and improve the fiber optic ribbon's resistance to bending. A take-up speed of 350 to 450 m / min can appropriately control the fiber optic ribbon's stress, reduce bending, and improve its resistance to bending.

[0052] In a third aspect, the present application provides an optical cable comprising the bend-resistant optical fiber ribbon according to the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0054] Figure 1 FIG. 1 is a schematic structural diagram of a bend-resistant optical fiber ribbon according to an embodiment of the present application.

[0055] Figure 2 This is a process flow chart of an embodiment of a method for preparing a bend-resistant optical fiber ribbon of the present application.

[0056] Description of Figure Numbers:

[0057] 100 anti-bend optical fiber ribbon; 1 optical fiber assembly; 11 optical unit; 111 optical fiber; 112 third protective layer; 2 first protective layer; 3 second protective layer; DETAILED DESCRIPTION

[0058] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of this application without making any creative efforts shall fall within the scope of protection of this application.

[0059] With the rapid development and increasing adoption of 5G technology, the communications industry is facing unprecedented opportunities and challenges. This not only significantly increases data transmission speeds and volumes, but also fosters innovation and application in cutting-edge fields like artificial intelligence and AI. This also places higher demands on outdoor optical cables, requiring higher fiber density and more convenient installation. Traditional stranded optical cables have a limited number of fiber cores, and during installation, each fiber must be individually spliced, which is time-consuming and labor-intensive.

[0060] Ribbon optical cable is a representative example of high-fiber-density optical cable. Its basic optical unit is a fiber ribbon, each of which can be made up of 4 to 24 optical fibers, depending on demand. Multiple fiber ribbons can be placed within a loose tube, and the cable is composed of one or more loose tubes, which exponentially increases the number of optical fibers. Compared to traditional loose tubes, which only contain 12 fibers, ribbon optical cable solves the problems of a small number of fibers and low fiber density. Because the basic optical unit is a fiber ribbon composed of multiple optical fibers, it is not necessary to fuse each fiber individually; only the ribbons need to be welded, saving construction time. Therefore, research on ribbon optical cables has become the primary approach used in the industry to increase fiber density and meet the needs of large-scale data transmission.

[0061] As optical cables are becoming increasingly lightweight, their outer diameters are shrinking, and the area occupied by the fiber ribbon within the casing is decreasing. When the cable bends, stress is transferred from the outside through the cable jacket to the loose tube, and then to the fiber ribbon, increasing additional fiber loss and affecting transmission performance. Furthermore, the fiber ribbon is prone to unraveling, resulting in poor flatness, making it difficult to align the individual fibers during splicing, reducing the success rate of splicing.

[0062] In view of this, the present application provides a bend-resistant optical fiber ribbon and a preparation method thereof, and an optical cable to solve the problem of large additional loss of existing optical fibers.

[0063] First, as Figure 1 As shown, the present application provides a bend-resistant optical fiber ribbon 100, including the following components arranged in sequence from the inside to the outside:

[0064] Optical fiber component 1;

[0065] A first protective layer 2 wrapped around the periphery of the optical fiber assembly 1; and

[0066] A second protective layer 3, wrapped around the outer periphery of the first protective layer 2;

[0067] The ratio of the modulus of the second protective layer 3 to the modulus of the first protective layer 2 is (1.15-1.5):1.

[0068] The present invention reduces the stress on the optical fiber 111 when the optical cable is bent by absorbing and buffering the stress of the inner and outer protective layers, thereby improving the bending resistance of the optical fiber 111, reducing additional attenuation, improving transmission performance, and ensuring signal stability. The second protective layer 3 has a large modulus, is less likely to cause loose ribbons, ensures the flatness and stability of the optical fiber ribbon, improves the success rate of optical fiber ribbon fusion, provides mechanical protection for the optical fiber 111, and has a strong covering force for all internal units; the first protective layer 2 has a small modulus and a soft texture, which improves the bending resistance of the optical fiber ribbon, provides stress absorption and buffering for the optical fiber 111, and reduces damage to the optical fiber 111 when the optical cable is bent. The ratio of the modulus of the second protective layer 3 to the modulus of the first protective layer 2 is (1.15-1.5):1, so that when the stress of the optical cable bending is transmitted to the optical fiber ribbon through the loose tube during construction or use, the second protective layer can mechanically protect the entire optical fiber ribbon, blocking part of the stress from continuing to be transmitted to the first protective layer and the optical fiber, and the first protective layer can absorb and buffer the remaining stress, further reducing the impact of stress on the optical fiber and reducing optical fiber damage and attenuation.

[0069] In conjunction with the first aspect, in some embodiments provided herein, the modulus of the first protective layer 2 is 300-350 MPa. Within this range, the modulus of the first protective layer 2 can provide stress absorption and buffering for the optical fiber 111, thereby reducing damage to the optical fiber 111 when the optical cable is bent. The modulus of the first protective layer 2 includes, but is not limited to, 300 MPa, 305 MPa, 310 MPa, 320 MPa, 325 MPa, 330 MPa, 340 MPa, 345 MPa, or 350 MPa.

[0070] In conjunction with the first aspect, in some embodiments provided herein, the modulus of the second protective layer 3 is 400-450 MPa. Within this modulus range, the second protective layer 3 can ensure stable flatness of the optical fiber ribbon and improve the success rate of optical fiber ribbon fusion splicing. The modulus of the second protective layer 3 includes, but is not limited to, 400 MPa, 405 MPa, 410 MPa, 420 MPa, 425 MPa, 430 MPa, 440 MPa, 445 MPa, or 450 MPa.

[0071] In combination with the first aspect, in some embodiments provided in the present application, the ratio of the elongation of the first protective layer 2 to the elongation of the second protective layer 3 is 1:(0.6~0.8). The ratio of the elongation of the first protective layer 2 to the elongation of the second protective layer 3 is within this range, which can reduce the impact of stress on the optical fiber when the optical fiber ribbon is bent.

[0072] In combination with the first aspect, in some embodiments provided in the present application, the elongation of the first protective layer 2 is 20% to 30%. Within this range of the elongation of the first protective layer 2, when the optical cable is bent, the influence of the first protective layer on the bending of the optical fiber can be reduced, thereby reducing the stress concentration of the optical fiber.

[0073] In combination with the first aspect, in some embodiments provided in the present application, the elongation of the second protective layer 3 is 10% to 20%. The elongation of the second protective layer 3 is within this range, so that the first protective layer and the optical fiber will not be excessively bent, thereby reducing the attenuation of the optical fiber.

[0074] In combination with the first aspect, in some embodiments provided in the present application, the material of the first protective layer 2 includes at least one of acrylics, epoxy resins and vinyl ethers. The first protective layer 2 uses at least one of the above materials to provide stress absorption and buffering for the optical fiber, thereby reducing damage to the optical fiber when the optical cable is bent.

[0075] In conjunction with the first aspect, in some embodiments provided herein, the material of the second protective layer 3 includes at least one of an acrylic resin, an epoxy resin, and a vinyl ether. Using at least one of these materials for the second protective layer 3 can stabilize the flatness of the optical fiber ribbon and improve the success rate of optical fiber ribbon fusion splicing. It can also provide mechanical protection for the first protective layer 2 and the optical fiber, improving the optical fiber's bending resistance.

[0076] It should be noted that the thickness of the first protective layer 2 and the second protective layer 3 may be equal or unequal, and may be 1.5 to 2.5 mm.

[0077] In conjunction with the first aspect, in some embodiments provided herein, the optical fiber assembly 1 includes a plurality of optical units 11 arranged side by side, each of which includes an optical fiber 111 and a third protective layer 112 arranged sequentially from the inside to the outside, the third protective layer 112 including a coloring layer, and the coloring layers of the plurality of optical units 11 each having an independent color. A common method for distinguishing optical fiber ribbons within the same loose tube is to use an inkjet printer to print characters on the surfaces of different optical fiber ribbons. The printing effect is affected by the inkjet printer, the properties of the printing ink, and the production speed, resulting in poor printing results and inconvenience in distinguishing optical fiber ribbons. By providing a coloring layer on the third protective layer 112, the present application can distinguish different optical fibers 111 by different colors, thereby facilitating the positioning of the optical fibers 111.

[0078] Second, as Figure 2 As shown, the present application provides a method for preparing a bend-resistant optical fiber ribbon, which is used to prepare the bend-resistant optical fiber ribbon of the first aspect, comprising the following steps:

[0079] Coating a first protective layer material on the outer surface of the optical fiber assembly, coating a second protective layer material on the outer surface of the first protective layer, and forming a first protective layer and a second protective layer respectively after curing;

[0080] Winding to form a bending-resistant optical fiber ribbon;

[0081] The coating pressure when coating the material of the first protective layer is smaller than the coating pressure when coating the material of the second protective layer.

[0082] The coating pressure when applying the material for the first protective layer is lower than the coating pressure when applying the material for the second protective layer. This allows for control of the modulus of the first and second protective layers, resulting in a greater modulus for the second protective layer than for the first. The high modulus of the second protective layer reduces ribbon loosening, ensures stable flatness of the optical fiber ribbon, and improves the success rate of fiber fusion splicing. The low modulus of the first protective layer provides stress absorption and buffering for the optical fiber, reducing damage to the optical fiber when the optical cable is bent. The inner and outer protective layer materials are coated and cured in a single step, eliminating the need for separate curing of the inner and outer layers. Only a single mold and curing unit are required, improving production efficiency and reducing costs.

[0083] It's important to note that the relationship between coating pressure and modulus is: pressure = modulus * strain, which primarily reflects changes in the mechanical properties of the resin during the coating process. Excessive pressure can lead to other problems, such as damage to the resin's microstructure and stress concentration. Excessive pressure can cause slippage between the resin and the optical fiber, resulting in uneven coating.

[0084] The viscosity of the material of the first protective layer at 25°C is 2500-3500 MPa·s, and the viscosity of the material of the second protective layer at 25°C is 4500-5500 MPa·s. Within this viscosity range, it is easy to control the coating pressure during coating and improve the bending resistance. The ratio of the needle penetration of the material of the first protective layer to the needle penetration of the material of the second protective layer is 1:(0.6-0.8). Within this range, the fluidity of the first protective layer can be higher than that of the second protective layer. Among them, the needle penetration (150g) of the material of the first protective layer is 350-450 (1 / 10mm). Within this range, the coating pressure of the first protective layer can be 90-110 bar, reducing the stress of the resin on the optical fiber and avoiding excessive attenuation during the production process. The needle penetration (150g) of the material of the second protective layer is 250-350 (1 / 10mm). Within this range, the coating pressure of the second protective layer can be 140-160 bar, thereby improving the covering force on the first protective layer and the optical fiber and obtaining a better thermal stripping effect.

[0085] Double-layer co-extrusion can be used to simultaneously coat the inner and outer layers of resin onto the ribbon's surface. The mold consists of an inner and outer die. The optical fiber enters the mold through the inlet, while the inner resin enters through the first outer hole, filling the first cavity formed by the inner and outer molds. The outer resin enters through the second outer hole, filling the second cavity. Under the same pressure, the inner and outer resins flow through the first and second outlets along the ribbon's travel direction, coating the optical fiber's surface.

[0086] In combination with the second aspect, in some embodiments provided in the present application, the coating pressure ratio of the material coating the first protective layer to the material coating the second protective layer is 1:(1.8~2.7). The coating pressure ratio of the material coating the first protective layer to the material coating the second protective layer is within this range, which can reduce the pressure of the first protective layer on the optical fiber, reduce the attenuation exceeding the standard during the production process, and increase the coating force of the second protective layer on the first protective layer and the optical fiber, thereby obtaining a better thermal stripping effect.

[0087] In conjunction with the second aspect, in some embodiments provided herein, the coating pressure for applying the material for the first protective layer is 90 to 110 bar. Within this range, the modulus of the first protective layer can be controlled within the range of 300 to 350 MPa, providing good elasticity and resistance to microbending and macrobending. Examples of coating pressures for applying the material for the first protective layer include, but are not limited to, 90 bar, 95 bar, 100 bar, 105 bar, or 110 bar.

[0088] In conjunction with the second aspect, in some embodiments provided herein, the coating pressure when applying the material for the second protective layer is 140 to 160 bar. Within this range, the modulus of the second protective layer can be controlled within the range of 400 to 450 MPa, resulting in a high modulus and high mechanical strength. Examples of coating pressures when applying the material for the second protective layer include, but are not limited to, 140 bar, 145 bar, 150 bar, 155 bar, or 160 bar.

[0089] Air pressure is applied to the coating material tank, pushing the coating material toward the mold. This ensures that the coating resin is evenly and thoroughly applied to the optical fiber surface. The inner and outer layer resins can be stored in separate tanks and applied simultaneously using a sandwich mold. To achieve good bending resistance, the outer layer's coating strength must be increased, so the coating pressure for the second protective layer must be higher than that for the first.

[0090] To ensure that both the inner and outer layers of resin have good fluidity, the mold temperature is set to 35-45°C, consistent with the temperature of the curing oven, to reduce the temperature fluctuation of the optical fiber. After coating, it enters the curing oven smoothly to improve the bending resistance.

[0091] In conjunction with the second aspect, in some embodiments provided herein, the ratio of the power of the ultraviolet light to the degree of curing when forming the first protective layer to the power of the ultraviolet light to the degree of curing when forming the second protective layer is 1:(0.7-0.9). When the ratio of the power of the ultraviolet light to the degree of curing when forming the first protective layer to the power of the ultraviolet light to the degree of curing when forming the second protective layer is within this range, the degree of curing of the second protective layer can be higher than that of the first protective layer, thereby improving the second protective layer's ability to resist external stress and simultaneously improving the first protective layer's ability to absorb and buffer stress.

[0092] In conjunction with the second aspect, in some embodiments provided herein, a ratio of the power of the ultraviolet light to the degree of curing when curing to form the first protective layer is 1300 to 1500. The ratio of the power of the ultraviolet light to the degree of curing when curing to form the first protective layer includes, but is not limited to, 1300, 1350, 1400, 1450, or 1500.

[0093] In conjunction with the second aspect, in some embodiments provided herein, a ratio of the power of the ultraviolet light to the degree of curing when curing to form the second protective layer is 1000 to 1200. The ratio of the power of the ultraviolet light to the degree of curing when curing to form the second protective layer includes, but is not limited to, 1000, 1050, 1100, 1150, or 1200.

[0094] Ultraviolet light curing is used to cure the inner and outer layers of resin from a fluid to a solid. After passing through the outer layer, the UV light intensity is partially attenuated when it reaches the inner layer. The ratio of UV light power to curing degree reflects the UV light intensity. The ratio of curing degree to UV light intensity for conventional optical fibers is 1800-2000. By controlling the ratio of curing degree to UV light intensity of the first protective layer, the stress on the optical fiber can be reduced. By controlling the ratio of curing degree to UV light intensity of the second protective layer, the strength of the second protective layer can be increased, ensuring the smoothness and stability of the optical fiber ribbon and improving the success rate of optical fiber ribbon fusion. When forming the first protective layer, the ratio of UV light power to curing degree is greater than the ratio of UV light power to curing degree when forming the first protective layer, ensuring that the second protective layer has a higher curing degree.

[0095] Since the resin is divided into two layers, inner and outer layers, curing needs to be carried out in an oxygen-free environment. The nitrogen flow rate in the curing furnace is set to 35-45L / min to improve the curing efficiency.

[0096] In conjunction with the second aspect, in some embodiments provided herein, the coating of the material for the first protective layer on the outer surface of the optical fiber assembly, before curing to form the first protective layer, includes:

[0097] Laying out multiple optical units and arranging them in parallel to form an optical fiber assembly;

[0098] When paying out the line, the pay-out tension of the two outer light units is smaller than the pay-out tension of the other light units in the middle position.

[0099] When the two optical fibers at the edge enter the mold, they are subject to friction from the upper and lower edges of the mold entrance, as well as the side edges of the mold entrance. The remaining optical fibers are subject only to friction from the upper and lower edges of the mold. To maintain consistent friction between each optical fiber, the payout tension of the two optical fibers at the edge is lower than that of the remaining fibers. This compensates for the side friction of the mold on the two optical fibers. This ensures consistent length for each optical fiber, maintains excellent flatness, and aligns the optical fibers at the edge with the others. When the ribbon bends, the force applied to each optical fiber is dispersed and essentially uniform, achieving bending resistance.

[0100] In conjunction with the second aspect, in some embodiments provided herein, the pay-off tension of the two outer light units is 0.4 N to 0.5 N. The pay-off tension of the two outer light units includes but is not limited to 0.4 N, 0.41 N, 0.42 N, 0.43 N, 0.44 N, or 0.45 N.

[0101] In conjunction with the second aspect, in some embodiments provided herein, the pay-off tension of the intermediate light unit is 0.5 N to 0.55 N. The pay-off tension of the intermediate light unit includes but is not limited to 0.5 N, 0.51 N, 0.52 N, 0.53 N, 0.54 N, or 0.55 N.

[0102] Taking a 12-core fiber ribbon as an example, 12 optical units of different colors are fixed to a separate payout frame. The two optical units at the edge of the ribbon (the first and 12th) are paid out with a tension of 0.4N to 0.45N, while the remaining optical units are paid out with a tension of 0.5N to 0.55N. All fibers are then gathered at the entrance of the coating die. This ensures that each optical unit is of uniform length, the ribbon is perfectly flat, and the optical units at the edge are aligned with the others. When the ribbon bends, the force applied to each optical unit is dispersed and essentially uniform, achieving bending resistance.

[0103] It should be noted that during the payout phase, the optical unit's surface becomes charged and attracts dust after experiencing rolling friction from the steering guide wheel and sliding friction from the fiber positioning rod. This affects the flatness of the fiber ribbon, reduces its bending resistance, and causes dust accumulation, which increases the stress on the fiber. This application adds an ion blower to remove the charge and dust from the fiber surface.

[0104] Setting up an ion blower can remove static electricity on the surface of the optical fiber. However, the ion blower will cause the optical fiber to shake, which will affect the flatness of the optical fiber ribbon, thereby reducing the bending resistance of the optical fiber ribbon. By placing the ion blower between the optical fiber pay-off and the coating resin, 100mm above the optical fiber, with the air outlet facing the optical fiber, and the air supply pressure being 0.15MPa, the static electricity on the surface of the optical fiber after treatment by the ion blower is 0kV, the static electricity removal effect is good, and the optical fiber has no obvious shaking, thereby improving the bending resistance.

[0105] In conjunction with the second aspect, in some embodiments provided herein, in the winding to form the bend-resistant optical fiber ribbon, the winding tension is 1.9 N to 2.0 N. The winding tension includes, but is not limited to, 1.9 N, 1.91 N, 1.92 N, 1.93 N, 1.94 N, 1.95 N, 1.96 N, 1.97 N, 1.98 N, 1.99 N, or 2 N.

[0106] In conjunction with the second aspect, in some embodiments provided herein, in the winding to form the bend-resistant optical fiber ribbon, the winding pitch of the winding is 3.6 to 3.8 mm, including but not limited to 3.6 mm, 3.65 mm, 3.7 mm, 3.75 mm, or 3.8 mm.

[0107] In combination with the second aspect, in some embodiments provided in the present application, in the winding process to form the bend-resistant optical fiber ribbon, the winding speed is 350-450 m / min.

[0108] The cured fiber optic ribbon is pulled along a crawler belt and finally wound onto a reel on a take-up frame. Compared to existing conventional resin fiber optic ribbons, the second protective layer of this bend-resistant fiber optic ribbon has a higher degree of cure and a smoother surface. To prevent slipping caused by the low friction between the two layers, the take-up tension and the cable arrangement pitch are increased to reduce bending and improve the fiber optic ribbon's resistance to bending. A take-up speed of 350 to 450 m / min can appropriately control the fiber optic ribbon's stress, reduce bending, and improve its resistance to bending.

[0109] In a third aspect, the present application provides an optical cable comprising the bend-resistant optical fiber ribbon according to the first aspect.

[0110] In summary, the stress absorption and buffering provided by the two inner and outer protective layers reduces stress on the optical fiber when the cable is bent, improving its bending resistance, reducing added attenuation, enhancing transmission performance, and ensuring signal stability. The second protective layer has a high modulus, which reduces ribbon unraveling, ensures stable flatness of the ribbon, and improves the success rate of ribbon splicing. The first protective layer has a low modulus, providing stress absorption and buffering for the optical fiber, reducing damage to the fiber when the cable is bent.

[0111] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0112] It should be noted that, in the present application, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or equipment comprising the elements. In the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly specified.

[0113] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A bending-resistant optical fiber ribbon, characterized in that: Including from the inside to the outside: fiber optic components; a first protective layer, wrapped around the periphery of the optical fiber assembly; as well as a second protective layer, wrapped around the outer periphery of the first protective layer; The ratio of the modulus of the second protective layer to the modulus of the first protective layer is (1.15-1.5):

1.

2. The bend-resistant optical fiber ribbon according to claim 1, wherein: The modulus of the first protective layer is 300-350 MPa; and / or, The modulus of the second protective layer is 400-450 MPa.

3. The bend-resistant optical fiber ribbon according to claim 1, wherein: The ratio of the elongation of the first protective layer to the elongation of the second protective layer is 1:(0.6-0.8); and / or, The elongation of the first protective layer is 20% to 30%; and / or, The elongation of the second protective layer is 10% to 20%.

4. The bend-resistant optical fiber ribbon according to claim 1, wherein: The material of the first protective layer includes at least one of acrylate, epoxy resin and vinyl ether; and / or, The material of the second protective layer includes at least one of acrylate, epoxy resin and vinyl ether.

5. The bend-resistant optical fiber ribbon according to claim 1, wherein: The optical fiber assembly includes a plurality of optical units arranged side by side, each optical unit includes an optical fiber and a third protective layer arranged sequentially from the inside to the outside, the third protective layer includes a colored layer, and the colored layers of the plurality of optical units have independent colors.

6. A method for preparing the bend-resistant optical fiber ribbon according to any one of claims 1 to 5, characterized in that: The following steps are involved: Coating a first protective layer material on the outer surface of the optical fiber assembly, coating a second protective layer material on the outer surface of the first protective layer, and forming a first protective layer and a second protective layer respectively after curing; Winding to form a bending-resistant optical fiber ribbon; The coating pressure when coating the material of the first protective layer is smaller than the coating pressure when coating the material of the second protective layer.

7. The method for preparing the bend-resistant optical fiber ribbon according to claim 6, wherein: The coating pressure ratio of the material coating the first protective layer to the material coating the second protective layer is 1:(1.8-2.7); and / or, The coating pressure when applying the material of the first protective layer is 90 to 110 bar; and / or, The coating pressure when applying the material of the second protective layer is 140 to 160 bar; and / or, The ratio of the power of the ultraviolet light to the curing degree when forming the first protective layer to the ratio of the power of the ultraviolet light to the curing degree when forming the second protective layer is 1:(0.7-0.9); and / or, When forming the first protective layer, the ratio of the power of the ultraviolet light to the curing degree is 1300 to 1500; and / or, When forming the second protective layer, the ratio of the power of the ultraviolet light to the curing degree is 1000-1200.

8. The method for preparing the bend-resistant optical fiber ribbon according to claim 6, wherein: The method of coating the outer surface of the optical fiber assembly with the material of the first protective layer, before curing to form the first protective layer, comprises: Laying out multiple optical units and arranging them in parallel to form an optical fiber assembly; When paying out the line, the pay-out tension of the two outer light units is smaller than the pay-out tension of the other light units in the middle position.

9. The method for preparing the bend-resistant optical fiber ribbon according to claim 8, wherein: The pay-off tension of the two outer optical units is 0.4N to 0.45N; and / or, The pay-off tension of the intermediate position optical unit is 0.5N to 0.55N; and / or, The take-up tension is 1.9N to 2.0N; and / or, The wire pitch of the take-up wire is 3.6mm to 3.8mm; and / or, The take-up speed is 350m / min~450m / min.

10. An optical cable, characterized in that: The invention comprises the bend-resistant optical fiber ribbon according to any one of claims 1 to 5.

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