Bending-resistant optical fiber ribbon, preparation method thereof and optical cable

Abstract

The invention discloses a bending-resistant optical fiber ribbon, a preparation method thereof and an optical cable, and relates to the field of optical information. The bending-resistant optical fiber ribbon comprises an optical fiber assembly, a first protection layer and a second protection layer which are sequentially arranged from inside to outside, the periphery of the optical fiber assembly is wrapped with the first protection layer, the periphery of the first protection layer is wrapped with the second protection layer, and the first protection layer is wrapped with the second protection layer. And the ratio of the modulus of the second protective layer to the modulus of the first protective layer is (1.15-1.5): 1. Through the stress absorption and buffering of the inner and outer protective layers, the stress of 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 protection layer is large in modulus and not prone to scattering, flatness stability of the optical fiber ribbon is guaranteed, the fusion success rate of the optical fiber ribbon is improved, the first protection layer is small in modulus, stress absorption and buffering are provided for the optical fiber, and damage to the optical fiber when the optical cable is bent is reduced.

Description

Technical Field

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

[0002] With the rapid development and gradual popularization of 5G technology, the communications industry has ushered in unprecedented opportunities and challenges. It has not only greatly improved the speed and quantity of data transmission, but also promoted the innovation and application of cutting-edge fields such as artificial intelligence and AI. It has also put forward higher requirements for outdoor optical cables, which need to meet the requirements of higher fiber density and more convenient cable construction. Traditional layer-stranded optical cables have a limited number of optical fiber cores; during construction, each fiber needs to be welded separately, which is time-consuming and labor-intensive.

[0003] Ribbon optical cable is a representative of high fiber density optical cable. Its basic optical unit is an optical fiber ribbon. The optical fibers in each optical fiber ribbon can be made into 4 to 24 fibers according to demand. Multiple optical fiber ribbons can be placed in a loose tube, and the optical cable is composed of one or more loose tubes, which increases the number of optical fiber cores exponentially. Compared with the traditional loose tube with only 12 optical fibers, the ribbon optical cable solves the problem of small number of optical fiber cores and low optical fiber density. Since the basic optical unit is an optical fiber ribbon composed of multiple optical fibers, when welding the optical fibers, it is not necessary to weld each optical fiber, but only to weld the optical fiber ribbon, which saves construction time. Therefore, the research on ribbon optical cables has become the main way to increase the density of optical fibers and meet the transmission of large data in the industry.

[0004] However, the stress is transferred from the outside to the loose tube through the ribbon cable sheath layer, 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 bending-resistant optical fiber ribbon and a preparation method thereof, and an optical cable, so as to solve the problem of large additional loss of existing optical fibers.

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

[0007] Fiber optic components;

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

[0009] A second protective layer, wrapped around 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] This 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 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 not prone to loose bands, 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 (1.15~1.5): 1, which can make the second protective layer mechanically protect the entire optical fiber ribbon when the stress of the optical cable bending is transmitted to the optical fiber ribbon through the loose tube during construction or use, and block 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. Within this range, the modulus of the first protective layer can provide stress absorption and buffering for the optical fiber, thereby 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). The ratio of the elongation of the first protective layer to the elongation of the second protective layer is within this range, which can reduce the influence of stress on the optical fiber 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 influence of the first protective layer on the bending of the optical fiber can be reduced when the optical cable is bent, thereby reducing the stress concentration of 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, and 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 and improve 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 a plurality of optical units arranged side by side, the optical units include optical fibers and a third protective layer arranged sequentially from the inside to the outside, the third protective layer includes a coloring layer, and the coloring layers of the plurality of optical units have independent colors. Usually, the way to distinguish optical fiber ribbons in the same loose tube is to use a spray printer to print characters on the surface of different optical fiber ribbons. The printing effect is affected by the spray printer, the properties of the printing ink and the production speed, and the printing effect may be poor, which makes it difficult to distinguish the optical fiber ribbons. The present application provides a coloring layer on the third protective layer, which can distinguish different optical fibers by different colors, thereby facilitating the positioning of the optical fiber.

[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 up 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 coating the material of the first protective layer is less than the coating pressure when coating the material of the second protective layer, so that the modulus of the first protective layer and the second protective layer can be controlled, so that the modulus of the second protective layer is greater than the modulus of the first protective layer. 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, providing 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 at one time, and there is no need to cure the inner and outer layers separately. Only one mold and one curing unit are needed, which can improve production efficiency and reduce costs.

[0026] It should be noted that the relationship between coating pressure and modulus is pressure = modulus * strain, which is mainly reflected in the change of mechanical properties of resin materials during coating. Excessive pressure may cause other problems such as damage to the resin microstructure and stress concentration. Excessive pressure may 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 2500-3500MPa·s, and the viscosity of the material of the second protective layer at 25°C is 4500-5500MPa·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 90-110bar, 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 140-160bar, which improves the coating force on the first protective layer and the optical fiber and can obtain a better thermal stripping effect.

[0028] The inner and outer layers of resin can be simultaneously coated on the surface of the optical fiber ribbon by double-layer co-extrusion. The mold is divided into an inner mold and an outer mold. The optical fiber enters from the mold inlet, and the inner layer of resin enters through the first hole of the outer mold, filling the first cavity formed by the inner and outer molds. The outer layer of resin enters through the second hole of the outer mold, filling the second cavity of the outer mold. Under the action of the same air pressure, the inner layer of resin and the outer layer of resin pass through the first outlet and the second outlet along the direction of travel of the optical fiber ribbon and are coated on the surface of the optical fiber.

[0029] In some embodiments, the coating pressure ratio of the material coated with the first protective layer to the material coated with the second protective layer is 1:(1.8-2.7). The coating pressure ratio of the material coated with the first protective layer to the material coated with the second protective layer within this range can reduce the pressure of the first protective layer on the optical fiber, reduce excessive attenuation during the production process, increase the coating force of the second protective layer on the first protective layer and the optical fiber, and obtain a better thermal stripping effect; and / or,

[0030] The coating pressure when coating the material of the first protective layer is 90 to 110 bar. When the coating pressure when coating 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 140-160 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 400-450 MPa, with a large modulus and high mechanical strength; and / or,

[0032] The ratio of the power of ultraviolet light to the curing degree when forming the first protective layer to the ratio of the power of ultraviolet light to the curing degree when forming the second protective layer is 1:(0.7-0.9), and the ratio of the power of ultraviolet light to the curing degree when forming the first protective layer to the ratio of the power of ultraviolet light to the curing degree when forming the second protective layer is within this range, so that 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 is also improved in absorbing and buffering 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 degree of curing is 1000-1200.

[0035] The coating material resin is applied evenly and fully on the surface of the optical fiber by applying air pressure to the coating material tank, thereby pushing the coating material toward the mold. The inner layer material resin and the outer layer material resin can be stored in two different storage tanks and coated at one time through a sandwich mold. In order to obtain good bending resistance, the coating force of the outer layer of the optical fiber ribbon needs to be increased, so the coating pressure of the second protective layer material is higher than that of the first protective layer material, and the first protective layer gives less stress to the optical fiber.

[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] The inner and outer layers of resin are cured from fluid to solid by ultraviolet light irradiation and curing. After the ultraviolet light intensity passes through the outer layer, it will be partially attenuated when it reaches the inner layer. The ratio of ultraviolet light power to curing degree reflects the intensity of ultraviolet light. The ratio of ultraviolet light power to curing degree of conventional optical fiber is 1800-2000. By controlling the ratio of ultraviolet light power to curing degree in the first protective layer, the stress on the optical fiber can be reduced. By controlling the ratio of ultraviolet light power to curing degree in the second protective layer, the strength of the second protective layer can be increased, the flatness of the optical fiber ribbon can be ensured to be stable, and the success rate of optical fiber ribbon fusion can be improved. When forming the first protective layer, the ratio of ultraviolet light power to curing degree is greater than the ratio of ultraviolet light power to curing degree when forming the first protective layer, so as to ensure that the second protective layer has a higher curing degree.

[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 material for coating the first protective layer on the outer surface of the optical fiber component, before curing to form the first protective layer, comprises:

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

[0041] When paying out the wire, the paying-out tension of the two outer optical units is smaller than the paying-out tension of the other optical units in the middle.

[0042] When the two optical units at the edge enter the mold, they will be affected by the upper and lower edges of the mold entrance, plus the friction of the side of the mold entrance. The remaining optical fibers are only affected by the upper and lower friction of the mold edge. In order to keep the relative friction of each optical unit consistent, the pay-off tension of the two optical units at the edge is lower than the pay-off tension of the remaining fibers, and the side friction of the mold on the two optical units at the edge is used as compensation. This can make the length of each optical unit consistent, the flatness of the optical fiber ribbon is good, and the optical units at the edge are on the same horizontal plane as other optical units. When the optical fiber ribbon is bent, the force on each optical unit is dispersed and basically consistent, achieving the purpose of anti-bending.

[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 tension of the take-up line is 1.9N to 2.0N; and / or,

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

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

[0048] Taking a 12-core optical fiber ribbon as an example, 12 optical units of different colors are fixed on a separate pay-off frame. After passing through the tension dance wheel, the pay-off tension of the two optical units (i.e. the first and the twelfth) at the edge of the optical fiber ribbon is 0.4N to 0.45N, and the pay-off tension of the remaining optical units is 0.5N to 0.55N. After that, all optical fibers are gathered at the entrance of the coating mold. This can make each optical unit of the same length, the flatness of the optical fiber ribbon is good, and the optical units at the edge are on the same horizontal plane as other optical units. When the optical fiber ribbon is bent, the force on each optical unit is dispersed and basically consistent, achieving the purpose of anti-bending.

[0049] It should be noted that during the pay-off stage, after the rolling friction of the steering guide wheel and the sliding friction of the optical fiber positioning rod, the surface of the optical unit will be charged and absorb dust, affecting the flatness of the optical fiber ribbon, reducing the bending resistance of the optical fiber ribbon, and causing dust accumulation, which increases the stress on the optical fiber. This application removes the charge and dust on the surface of the optical fiber by adding an ion blower.

[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 of 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 optical fiber ribbon is pulled by a crawler and finally wound on the reel of the take-up frame. Compared with the existing conventional resin optical fiber ribbon, the curing degree of the second protective layer of the anti-bending optical fiber ribbon of the present application is higher and the surface is smoother. In order to avoid slipping due to the small friction between the two layers, the bending of the optical fiber ribbon can be reduced by increasing the take-up tension and the line arrangement pitch, and the anti-bending performance can be improved. The take-up speed is 350-450m / min, which can properly control the stress of the optical fiber ribbon, reduce bending, and improve the anti-bending performance.

[0052] In a third aspect, the present application provides an optical cable, comprising the bend-resistant optical fiber ribbon of 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 drawings required for use in the description of the embodiments will be briefly introduced below. 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 creative work.

[0054] Figure 1 Schematic diagram of the structure 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-bending 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] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0059] With the rapid development and gradual popularization of 5G technology, the communications industry has ushered in unprecedented opportunities and challenges. It has not only greatly improved the speed and quantity of data transmission, but also promoted the innovation and application of cutting-edge fields such as artificial intelligence and AI. It has also put forward higher requirements for outdoor optical cables, which need to meet the requirements of higher fiber density and more convenient cable construction. Traditional layer-stranded optical cables have a limited number of optical fiber cores; during construction, each fiber needs to be welded separately, which is time-consuming and labor-intensive.

[0060] Ribbon optical cable is a representative of high fiber density optical cable. Its basic optical unit is an optical fiber ribbon. The optical fibers in each optical fiber ribbon can be made into 4 to 24 fibers according to demand. Multiple optical fiber ribbons can be placed in a loose tube, and the optical cable is composed of one or more loose tubes, which increases the number of optical fiber cores exponentially. Compared with the traditional loose tube with only 12 optical fibers, the ribbon optical cable solves the problem of small number of optical fiber cores and low optical fiber density. Since the basic optical unit is an optical fiber ribbon composed of multiple optical fibers, when welding the optical fibers, it is not necessary to weld each optical fiber, but only to weld the optical fiber ribbon, which saves construction time. Therefore, the research on ribbon optical cables has become the main way to increase the density of optical fibers and meet the transmission of large data in the industry.

[0061] At present, as the optical cable is gradually developing towards the direction of lightness, the outer diameter of the optical cable is gradually reduced, and the area ratio of the optical fiber ribbon in the casing is gradually reduced. When the optical cable is bent, the stress is transmitted from the outside through the optical cable sheath layer 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. In addition, the optical fiber ribbon is prone to looseness and poor flatness. When welding, each optical fiber cannot be smoothly aligned, which reduces the success rate of welding.

[0062] In view of this, the present application provides a bending-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 bending-resistant optical fiber ribbon 100, including:

[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 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 application reduces the stress on the optical fiber 111 when the optical cable is bent, improves the bending resistance of the optical fiber 111, reduces additional attenuation, improves transmission performance, and ensures signal stability through stress absorption and buffering of the inner and outer protective layers. The second protective layer 3 has a large modulus, is not prone to loose bands, 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 large covering force for all internal units; the first protective layer 2 has a small modulus and a soft texture, improves the bending resistance of the optical fiber ribbon, provides stress absorption and buffering for the optical fiber 111, and reduces the 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 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, block 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 combination with the first aspect, in some embodiments provided in the present application, 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, and reduce 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 combination with the first aspect, in some embodiments provided in the present application, the modulus of the second protective layer 3 is 400-450 MPa. The modulus of the second protective layer 3 within this range can ensure the stability of the flatness of the optical fiber ribbon and improve the success rate of optical fiber ribbon fusion. 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 influence 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 acrylic resins, 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 combination with the first aspect, in some embodiments provided in the present application, the material of the second protective layer 3 includes at least one of acrylic resins, epoxy resins and vinyl ethers. The second protective layer 3 uses at least one of the above materials to stabilize the flatness of the optical fiber ribbon and improve the success rate of optical fiber ribbon fusion. It can also provide mechanical protection for the first protective layer 2 and the optical fiber and improve the bending resistance of the optical fiber.

[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 combination with the first aspect, in some embodiments provided in the present application, the optical fiber assembly 1 includes a plurality of optical units 11 arranged side by side, the optical unit includes an optical fiber 111 and a third protective layer 112 arranged sequentially from the inside to the outside, the third protective layer 112 includes a coloring layer, and the coloring layers of the plurality of optical units 11 have independent colors. Usually, the way to distinguish optical fiber ribbons in the same loose tube is to use a spray printer to print characters on the surface of different optical fiber ribbons. The printing effect is affected by the spray printer, the properties of the printing ink and the production speed, and the printing effect may be poor, which makes it difficult to distinguish the optical fiber ribbons. The present application provides a coloring layer on the third protective layer 112, and can distinguish different optical fibers 111 by different colors, which facilitates the positioning of the optical fiber 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 up 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 coating the material of the first protective layer is less than the coating pressure when coating the material of the second protective layer, so that the modulus of the first protective layer and the second protective layer can be controlled, so that the modulus of the second protective layer is greater than the modulus of the first protective layer. 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, providing 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 at one time, and there is no need to cure the inner and outer layers separately. Only one mold and one curing unit are needed, which can improve production efficiency and reduce costs.

[0083] It should be noted that the relationship between coating pressure and modulus is pressure = modulus * strain, which is mainly reflected in the change of mechanical properties of resin materials during coating. Excessive pressure may cause other problems such as damage to the resin microstructure and stress concentration. Excessive pressure may 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 2500-3500MPa·s, and the viscosity of the material of the second protective layer at 25°C is 4500-5500MPa·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 90-110bar, 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 140-160bar, which improves the coating force on the first protective layer and the optical fiber and can obtain a better thermal stripping effect.

[0085] The inner and outer layers of resin can be simultaneously coated on the surface of the optical fiber ribbon by double-layer co-extrusion. The mold is divided into an inner mold and an outer mold. The optical fiber enters from the mold inlet, and the inner layer of resin enters through the first hole outside, filling the first cavity formed by the inner and outer molds. The outer layer of resin enters through the second hole of the outer mold, filling the second cavity of the outer mold. Under the action of the same air pressure, the inner layer of resin and the outer layer of resin pass through the first outlet and the second outlet along the direction of the optical fiber ribbon and are coated on the surface of the optical fiber.

[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 excessive attenuation 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 in the present application, the coating pressure when coating the material of the first protective layer is 90 to 110 bar. When the coating pressure when coating 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. The coating pressure when coating the material of the first protective layer includes but is 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 in the present application, 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, with a large modulus and high mechanical strength. The coating pressure when coating the material of the second protective layer includes but is not limited to 140 bar, 145 bar, 150 bar, 155 bar or 160 bar.

[0089] The coating material resin is applied evenly and fully on the surface of the optical fiber by applying air pressure to the coating material tank to push the coating material toward the mold. The inner layer material resin and the outer layer material resin can be placed in two different storage tanks and coated at one time through a sandwich mold. In order to obtain good bending resistance, the outer layer coating force needs to be increased, so the coating pressure of the second protective layer material must be higher than that of the first protective layer material.

[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 in the present application, the ratio of the power of ultraviolet light to the curing degree when forming the first protective layer to the ratio of the power of 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 ultraviolet light to the curing degree when forming the first protective layer to the ratio of the power of 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 is also improved in absorbing and buffering stress.

[0092] In conjunction with the second aspect, in some embodiments provided in the present application, the ratio of the power of the ultraviolet light to the curing degree when curing to form the first protective layer is 1300 to 1500. The ratio of the power of the ultraviolet light to the curing degree 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 in the present application, the ratio of the power of the ultraviolet light to the curing degree when curing to form the second protective layer is 1000 to 1200. The ratio of the power of the ultraviolet light to the curing degree when curing to form the second protective layer includes but is not limited to 1000, 1050, 1100, 1150 or 1200.

[0094] The inner and outer layers of resin are cured from fluid to solid by ultraviolet light irradiation curing. After the ultraviolet light intensity passes through the outer layer, it will be partially attenuated when it reaches the inner layer. The ratio of ultraviolet light power to curing degree reflects the intensity of ultraviolet light. The ratio of curing degree to ultraviolet light intensity of conventional optical fiber is 1800-2000. By controlling the ratio of curing degree to ultraviolet light intensity of the first protective layer, the stress on the optical fiber can be reduced. By controlling the ratio of curing degree to ultraviolet light intensity of the second protective layer, the strength of the second protective layer can be increased, the flatness of the optical fiber ribbon can be ensured to be stable, and the success rate of optical fiber ribbon fusion can be improved. When forming the first protective layer, the ratio of ultraviolet light power to curing degree is greater than the ratio of ultraviolet light power to curing degree when forming the first protective layer, so as to ensure 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 in the present application, the material for coating 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 a plurality of optical units and arranging them in parallel to form an optical fiber assembly;

[0098] When paying out the wire, the paying-out tension of the two outer optical units is smaller than the paying-out tension of the other optical units in the middle.

[0099] When the two optical units at the edge enter the mold, they will be affected by the upper and lower edges of the mold entrance, plus the friction of the side of the mold entrance. The remaining optical fibers are only affected by the upper and lower friction of the mold edge. In order to keep the relative friction of each optical unit consistent, the pay-off tension of the two optical units at the edge is lower than the pay-off tension of the remaining fibers, and the side friction of the mold on the two optical units at the edge is used as compensation. This can make the length of each optical unit consistent, the flatness of the optical fiber ribbon is good, and the optical units at the edge are on the same horizontal plane as other optical units. When the optical fiber ribbon is bent, the force on each optical unit is dispersed and basically consistent, achieving the purpose of anti-bending.

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

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

[0102] Taking a 12-core optical fiber ribbon as an example, 12 optical units of different colors are fixed on a separate pay-off frame. After passing through the tension dance wheel, the pay-off tension of the two optical units (i.e. the first and the twelfth) at the edge of the optical fiber ribbon is 0.4N to 0.45N, and the pay-off tension of the remaining optical units is 0.5N to 0.55N. After that, all optical fibers are gathered at the entrance of the coating mold. This can make each optical unit of the same length, the flatness of the optical fiber ribbon is good, and the optical units at the edge are on the same horizontal plane as other optical units. When the optical fiber ribbon is bent, the force on each optical unit is dispersed and basically consistent, achieving the purpose of anti-bending.

[0103] It should be noted that during the pay-off stage, after the rolling friction of the steering guide wheel and the sliding friction of the optical fiber positioning rod, the surface of the optical unit will be charged and absorb dust, affecting the flatness of the optical fiber ribbon, reducing the bending resistance of the optical fiber ribbon, and causing dust accumulation, which increases the stress on the optical fiber. This application removes the charge and dust on the surface of the optical fiber by adding an ion blower.

[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 of 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 combination with the second aspect, in some embodiments provided in the present application, in the winding to form the bending-resistant optical fiber ribbon, the winding tension is 1.9N to 2.0N. The winding tension includes but is not limited to 1.9N, 1.91N, 1.92N, 1.93N, 1.94N, 1.95N, 1.96N, 1.97N, 1.98N, 1.99N or 2N.

[0106] In conjunction with the second aspect, in some embodiments provided in the present application, in the winding to form the anti-bending optical fiber ribbon: the winding pitch of the winding is 3.6-3.8 mm. The winding pitch of the winding includes but is 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 optical fiber ribbon is pulled by a crawler and finally wound on the reel of the take-up frame. Compared with the existing conventional resin optical fiber ribbon, the curing degree of the second protective layer of the anti-bending optical fiber ribbon of the present application is higher and the surface is smoother. In order to avoid slipping due to the small friction between the two layers, the bending of the optical fiber ribbon can be reduced by increasing the take-up tension and the line arrangement pitch, and the anti-bending performance can be improved. The take-up speed is 350-450m / min, which can properly control the stress of the optical fiber ribbon, reduce bending, and improve the anti-bending performance.

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

[0110] In summary, through the stress absorption and buffering of the inner and outer protective layers, the stress 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 welding. 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.

[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" etc. 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 representations 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 a suitable manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the 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 only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including 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 more restrictions, the elements defined by the sentence "comprise one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically stipulated.

[0113] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A bending-resistant optical fiber ribbon, characterized in that: Including from inside to 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 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: The optical fiber assembly includes a plurality of optical units arranged side by side, wherein the optical units include optical fibers and a third protective layer arranged sequentially from the inside to the outside, wherein the third protective layer includes a coloring layer, and the coloring layers of the plurality of optical units have respective 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 up 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, characterized in that: 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 coating the material of the first protective layer is 90 to 110 bar; and / or, The coating pressure when coating the material of the second protective layer is 140 to 160 bar; and / or, The ratio of the power of ultraviolet light to the curing degree when forming the first protective layer to the power of 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, characterized in that: The material for coating the first protective layer on the outer surface of the optical fiber assembly, before curing to form the first protective layer, comprises: Laying out a plurality of optical units and arranging them in parallel to form an optical fiber assembly; When paying out the wire, the paying-out tension of the two outer optical units is smaller than the paying-out tension of the other optical units in the middle.

9. The method for preparing the bend-resistant optical fiber ribbon according to claim 8, characterized in that: 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 tension of the take-up line 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 as claimed in any one of claims 1 to 5.

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