Indoor micro beam tube type optical cable

Abstract

The invention discloses an indoor micro-beam tube type optical cable, which comprises a micro-beam tube, aramid yarn, a tearing rope and an outer sheath, and is characterized in that the outer sheath is arranged outside the micro-beam tube and the tearing rope, and the outer sheath is made of a low-smoke halogen-free material with an oxygen index greater than or equal to 40%; the micro beam tube comprises an optical fiber, a filling layer and an inner sheath, the inner sheath is arranged on the outer side of the optical fiber, and the filling layer is filled between the optical fiber and the inner sheath. The invention provides a dynamic adaptation strategy of a filling layer material and an inner layer sheath material, the provided indoor micro beam tube type optical cable can guarantee the structural integrity of the sheath, gives consideration to protection performance and construction operability, solves the contradiction that the inner layer sheath of a traditional optical cable is insufficient in protection or too hard to operate, can block moisture intrusion in a humid environment, and also can prevent the inner layer sheath from being damaged. And external force impact can be buffered through the filling layer, so that stable operation of the optical cable under extreme weather conditions such as high temperature and cold and complex scenes such as industrial oil contamination and high humidity can be ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of communication optical cables, in particular to an indoor micro-beam tube type optical cable. BACKGROUND

[0002] With the rapid development of 5G communication, data center and other core communication infrastructures towards high density and high reliability, optical cables as the key carrier of information transmission need to meet multiple requirements such as high-speed transmission, narrow space adaptation, complex environment (such as oil pollution, temperature and humidity fluctuation) resistance, fire safety and convenient construction in scenarios such as data center cabinet wiring and indoor deployment of 5G base stations.

[0003] However, traditional indoor optical cables have many performance shortcomings, which are difficult to match the above-mentioned scene requirements: first, the sheath is mostly ordinary polyethylene (PE) or conventional low-smoke zero-halogen (LSZH) material, which has poor oil corrosion resistance and is easy to penetrate, swell, age and break down in industrial oil pollution and complex outdoor environments, resulting in exposure of optical fibers, signal failure and even breakage; second, the flame retardant grade is low, and it is easy to continue to burn when exposed to fire, releasing toxic gases and smoke, which threatens personnel safety and damages precision equipment; third, the mechanical properties and environmental adaptability are insufficient, and the optical fibers are easy to deform and break during construction and maintenance, conventional G652 optical fibers are sensitive to bending, have obvious attenuation in narrow space wiring, and cannot adapt to a wide temperature environment of-40 ℃~80 ℃; fourth, the construction efficiency and reliability are poor, and the optical fibers are easy to be damaged during stripping with special tools, which is low in construction efficiency and high in misconnection rate.

[0004] The existing improvement schemes in the industry are mostly aimed at single defects, such as using glass fiber reinforced plastic (FRP) to improve mechanical strength and adding flame retardants to improve flame retardancy, but they do not achieve multiple performance coordination. For example, increasing the content of flame retardants can improve the oxygen index, but it will increase the hardness of the sheath and reduce the flexibility, which will increase the difficulty of construction and bending; setting a tear rope to simplify stripping does not match the optical fiber positioning design, and still cannot solve the misconnection problem. With the development of communication infrastructure towards high density and high reliability, the market requires optical cables to maintain low attenuation in a wide temperature environment of-40 ℃~80 ℃, meet strict flame retardant and waterproof standards, and adapt to complex industrial scenarios, so it is necessary to develop an indoor micro-beam tube type optical cable with high flame retardancy, oil resistance, excellent mechanical properties, wide temperature adaptability and convenient construction. SUMMARY

[0005] To solve the above technical problems, the purpose of the present application is to provide an indoor micro-beam tube type optical cable, which uses a low-smoke zero-halogen material with an oxygen index of ≥40%, designs a double-layer flame-retardant reinforced structure and predefines a stripping protrusion, to specifically solve the core pain points of traditional optical cables in terms of flame retardancy, mechanical properties and construction efficiency, to provide a high-reliability and easy-to-deploy transmission solution for 5G base stations, data centers and other scenarios, and to effectively improve the stability and safety of communication networks.

[0006] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0007] An indoor micro-tube type optical cable includes a micro-tube, aramid yarn, tear cord and an outer sheath. The outer sheath is disposed on the outside of the micro-tube and the tear cord. The aramid yarn is filled between the micro-tube and the outer sheath. The outer sheath is made of a low-smoke halogen-free material with an oxygen index ≥40%.

[0008] The micro-tube includes an optical fiber, a filling layer, and an inner sheath. The inner sheath is disposed on the outside of the optical fiber, and the filling layer is filled between the optical fiber and the inner sheath.

[0009] The filling layer is made of fiber paste, water-resistant yarn, or aramid yarn. When the filling layer is made of fiber paste, the inner sheath is made of an oil-resistant, low-smoke, halogen-free material. The oil-resistant, low-smoke, halogen-free material comprises the following components by weight: 52-60 parts of blended EVA, 23-35 parts of palygorskite fiber, 50-75 parts of flame retardant, 16.5-20.3 parts of graphene oxide, 5-17 parts of ethylene propylene diene monomer (EPDM), and 6.85-10.8 parts of crosslinking agent. When the filling layer is made of water-resistant yarn or aramid yarn, the inner sheath is made of a flame-retardant, low-smoke, halogen-free material with a Shore hardness of 54-62 HD.

[0010] This invention proposes a dynamic adaptation strategy between the filler layer material and the inner sheath material. When the filler layer material is a fibrous paste, although the fibrous paste provides excellent waterproof and cushioning properties, the base oil and additives in it may cause swelling of the polymer material. Therefore, this invention specifically designs an oil-resistant, low-smoke, halogen-free fibrous paste material. Its core lies in the introduction of ethylene propylene rubber, utilizing its excellent oil resistance and chemical corrosion resistance to form an interpenetrating network structure with the EVA matrix, effectively resisting the erosion of the fibrous paste. Simultaneously, the addition of palygorskite fibers and graphene oxide not only significantly improves the material's mechanical and flame-retardant properties, but its layered structure also physically blocks the penetration pathways of small molecules (such as oil in the fibrous paste), further enhancing oil resistance.

[0011] When the filling layer is made of water-resistant yarn or aramid yarn, such filling materials have lower requirements for the chemical stability of the sheath, but higher requirements for mechanical protection and ease of construction. Therefore, this invention selects a flame-retardant, low-smoke, halogen-free material with a Shore hardness of 54-62 HD, which can balance the protection and operability of the optical cable.

[0012] Furthermore, the microtube bundles are in one or more groups.

[0013] Multiple micro-tube bundles in the optical cable can be formed by spiral twisting or SZ (bidirectional) twisting before being covered with an outer sheath. The twisting pitch is 1-3 m, and the maximum number of cores in the optical cable can reach 576. This twisting structure facilitates the removal and splicing of micro-tube bundles during construction, and the splicing error rate is <0.1%, reducing construction difficulty and time cost.

[0014] Furthermore, the optical fiber may be one or more.

[0015] Furthermore, the optical fiber is a G657 type bend-insensitive fiber, which can effectively reduce optical fiber transmission loss even under small bending radius conditions, and is suitable for wiring needs in confined spaces.

[0016] The extremely high specific strength and specific modulus of aramid yarn can effectively absorb and disperse axial tensile stress, significantly improving the tensile strength of optical cables. At the same time, its loose filling state can also absorb energy through its own deformation when subjected to lateral compression, playing a buffering and protective role.

[0017] Furthermore, the outer sheath is a low-smoke halogen-free (LSZH) sheath.

[0018] Furthermore, the low-smoke halogen-free material comprises the following components by weight percentage: 12-30% blended EVA, 5-20% ethylene-octene copolymer, 8-30% bimodal linear low-density polyethylene, 5-15% maleic anhydride-grafted PE, 20-50% flame retardant, 2-10% organosilicon charring agent, 1-3% nitrogen-based synergist, and 1-3% phosphate ester.

[0019] Further, the blended EVA comprises an ethylene-vinyl acetate copolymer with a VA (vinyl acetate) content of 5-40 wt% in a mass ratio of (60-80):(20-40) and a blend of ethylene-vinyl acetate copolymers with a VA content of more than 40%.

[0020] Furthermore, the bimodal linear low-density polyethylene is a polymer formed by using ethylene as the main raw material and a small amount of α-olefins, catalysts, etc., preferably using bimodal linear low-density polyethylene with brands such as Borealis 2230 available on the market.

[0021] Furthermore, the flame retardant includes aluminum hydroxide and magnesium hydroxide.

[0022] Furthermore, the average particle size of the aluminum hydroxide or magnesium hydroxide is less than 1 micrometer.

[0023] Furthermore, the mass ratio of aluminum hydroxide to magnesium hydroxide is (10-25):(10-25).

[0024] Furthermore, the nitrogen-based synergist is melamine.

[0025] The low-smoke, halogen-free material of the outer sheath can reduce smoke concentration by 60% and toxic gas release by 80% when burning, meeting environmental protection requirements and fire safety standards.

[0026] Furthermore, the inner sheath is an inner LSZH sheath.

[0027] Furthermore, the flame retardant in the oil-resistant, low-smoke, halogen-free material is aluminum hydroxide or magnesium hydroxide.

[0028] Furthermore, the average particle size of the aluminum hydroxide or magnesium hydroxide is less than 1 micrometer.

[0029] Oil-resistant, low-smoke, halogen-free materials can effectively prevent the seepage of fibrous paste and avoid the outer layer of low-smoke, halogen-free materials from swelling and deforming due to contact with fibrous paste; flame-retardant, low-smoke, halogen-free materials with a Shore hardness of 54-62 HD provide sufficient protection for the internal structure while maintaining a certain degree of flexibility in the sheath, facilitating construction operations.

[0030] Furthermore, the outer diameter of the inner sheath is 0.9-1.5 mm, suitable for 1-12 core optical fibers.

[0031] Furthermore, the inner sheath has a wall thickness of 0.1-0.15 mm, which can be torn open by hand without the need for special tools during construction, increasing construction efficiency by 50%.

[0032] Furthermore, the blended EVA of the oil-resistant, low-smoke, halogen-free material comprises an ethylene-vinyl acetate copolymer with a VA content of 5-40 wt% in a mass ratio of (60-80):(20-40) and a blend of ethylene-vinyl acetate copolymers with a VA content higher than 40%.

[0033] Furthermore, the palygorskite fiber of the oil-resistant, low-smoke, halogen-free material is silicate-palygorskite fiber.

[0034] Furthermore, the crosslinking agent of the oil-resistant, low-smoke, halogen-free material is dicumyl peroxide.

[0035] Furthermore, a water-blocking strip is provided between the outer side of the micro-tube and the tear rope and the outer sheath.

[0036] When the optical cable sheath is accidentally damaged, the water-blocking tape can expand rapidly, block the water inlet channel, and prevent water from spreading longitudinally along the optical cable, thereby protecting the internal optical fibers and improving the reliability of the optical cable in humid environments.

[0037] Furthermore, a central reinforcement member is provided at the center of the indoor micro-tube optical cable.

[0038] Furthermore, the central reinforcement is made of glass fiber reinforced plastic (FRP). FRP is lightweight, high-strength, and non-conductive. It provides rigid support for the entire optical cable, making the cable core structure less prone to collapse when subjected to enormous lateral pressure (such as construction trampling or heavy object compression), thereby protecting the internal micro-tubes and optical fibers from damage.

[0039] The microtube surrounds the central reinforcing member FRP by spiral twisting or SZ twisting, and the twisting pitch is controlled to be 1-3 m. This twisting structure design facilitates the removal and splicing of the microtube during construction.

[0040] Furthermore, the outer sheath is embedded with a reinforcing member.

[0041] Furthermore, at least two glass fiber reinforced plastic rods are embedded within the outer sheath.

[0042] Furthermore, the glass fiber reinforced plastic rod is symmetrically arranged around the outer sheath in the circumferential direction.

[0043] Embedding reinforcements (such as fiberglass reinforced plastic rods) inside the outer sheath can further enhance the optical cable's resistance to lateral pressure and impact, making it suitable for special environments with higher requirements for mechanical performance.

[0044] Furthermore, the reinforcing members embedded in the outer sheath of the optical cable and the central reinforcing members set in the center of the optical cable can be set separately or in combination according to actual needs.

[0045] Furthermore, the outer sheath is provided with peeling protrusions or color stripes.

[0046] This invention employs a design with tear ropes and pre-set stripping protrusions in the optical cable. During construction, a special stripping tool is used to strip the cable at the stripping protrusions or color-marked areas, which allows for precise control of the stripping position, avoids damage to the central reinforcing component FRP, and improves construction efficiency. Subsequently, the sheath can be stripped manually using the tear rope, which also improves construction efficiency.

[0047] Compared with the prior art, the above-described technical solution of the present invention has the following advantages:

[0048] 1. The indoor micro-tube optical cable provided by this invention adopts a design where the filling layer material and the inner sheath material are compatible. When the filling layer material is fiber grease, the inner sheath is made of oil-resistant grease-type low-smoke halogen-free material, which can effectively block the fiber grease from seeping out and prevent the outer low-smoke halogen-free material from swelling and deforming due to contact with the fiber grease, thus ensuring the integrity of the sheath structure. When the filling layer material is water-blocking yarn or aramid yarn, the inner sheath is made of flame-retardant low-smoke halogen-free material with a Shore hardness of 54-62 HD, which can provide sufficient physical protection for the internal optical fiber and filling layer while maintaining the flexibility of the sheath, taking into account both protective performance and ease of construction, thus solving the contradiction of insufficient protection or excessive rigidity and difficulty in operation of the inner sheath of traditional optical cables.

[0049] 2. The outer sheath of the indoor micro-tube optical cable provided by this invention is made of high flame-retardant, low-smoke, halogen-free material with an oxygen index ≥40%. During combustion, the smoke concentration is reduced by 60% and the release of toxic gases is reduced by 80%, which complies with relevant environmental protection and fire safety standards such as GB / T 19666-2019 "General Rules for Flame-Retardant and Fire-Resistant Wires, Cables or Optical Cables", and greatly improves the safety and environmental protection of the optical cable during use.

[0050] 3. The indoor micro-tube optical cable provided by this invention, through structural design such as aramid yarn layer reinforcement and FRP central reinforcement, improves the tensile performance of the optical cable to over 660 N and the flattening performance to 1200 N / 100 mm, effectively enhancing its tensile and flattening resistance and reducing fiber breakage issues during construction or routine maintenance. Simultaneously, when paired with G657 bend-insensitive optical fiber, it can effectively reduce fiber transmission loss even in confined spaces (such as inside a server rack) with small-radius bends. It is suitable for various scenarios such as community and building communication networks, 5G base station construction and maintenance, data center internal cabling, and campus network construction, extending the lifespan of the optical cable and reducing the maintenance cost of communication links.

[0051] 4. The indoor micro-tube optical cable provided by this invention, through flexible selection of the filling layer and optional setting of the water-blocking strip, can achieve multiple functions such as waterproofing and buffering, and its waterproof performance meets the GB / T 7424.2-2008 standard. This indoor micro-tube optical cable can not only block water intrusion in humid environments, but also buffer external impacts through the filling layer. At the same time, it is suitable for extreme climatic conditions such as high temperature and cold, ensuring stable operation of the optical cable in a wide temperature range of -40 ℃ to 80 ℃ and in complex scenarios such as industrial oil pollution and high humidity.

[0052] 5. The indoor micro-tube optical cable provided by this invention conforms to the national standard GB 31247-2014 "Classification of Combustion Performance of Cables and Optical Cables", reaching Class B1 (flame-retardant material), and meets the following core indicators: Combustion growth rate index (FIGRA) ≤120W / s; Total heat release within 600 s ≤7.5 MJ; Smoke toxicity: reaching Class ZA2 (smoke density level ≤90, smoke toxicity concentration ≤1.3LC50); Combustion drips: no phenomenon of molten drips igniting filter paper. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the structure of the indoor micro-tube type optical cable in Example 1.

[0054] Figure 2 This is a schematic diagram of the structure of the indoor micro-tube type optical cable in Example 2.

[0055] Explanation of reference numerals in the attached diagram: 1. Microtube; 2. Optical fiber; 3. Inner LSZH sheath; 4. Aramid yarn; 5. Tear cord; 6. Water-blocking tape; 7. Outer LSZH sheath; 8. Reinforcing FRP; 9. Central reinforcing FRP; 10. Peeling protrusion; 11. Filler layer. Detailed Implementation

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0057] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0058] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0059] In the following examples, the tensile property test standard is Method E1 in GB / T 7424.2, and the flattening test standard is Method E3 in GB / T 7424.2.

[0060] Example 1

[0061] A schematic diagram of an indoor micro-tube optical cable is shown below. Figure 1As shown, the device includes a microtube bundle 1, aramid yarn 4, tear cord 5, water-blocking tape 6, and an outer LSZH sheath 7. The water-blocking tape 6 is disposed on the outside of the microtube bundle 1 and the tear cord 5, and the outer LSZH sheath 7 is disposed on the outside of the water-blocking tape 6. The aramid yarn 4 is filled between the microtube bundle 1 and the water-blocking tape 6, and the outer LSZH sheath 7 is made of a low-smoke halogen-free material with an oxygen index ≥40%. The low-smoke halogen-free material comprises the following components by mass percentage: 20% blended EVA, 15% ethylene-octene copolymer, 17% bimodal linear low-density polyethylene, 8% maleic anhydride-grafted PE, 30% aluminum hydroxide and magnesium hydroxide (mass ratio 1:1), 6% organosilicon charring agent, 2% melamine, and 2% phosphate ester.

[0062] The micro-tube 1 includes an optical fiber 2, a filling layer 11 and an inner LSZH sheath 3. The inner LSZH sheath 3 is disposed on the outside of the optical fiber 2, and the filling layer 11 is filled between the optical fiber 2 and the inner LSZH sheath 3.

[0063] The filling layer is made of fiber paste, and the inner sheath is made of oil-resistant paste-type low-smoke halogen-free material. The oil-resistant paste-type low-smoke halogen-free material includes the following components by weight: 55 parts of blended EVA, 30 parts of silicate-palmitite fiber, 60 parts of aluminum hydroxide, 18 parts of graphene oxide, 10 parts of ethylene propylene rubber, and 8 parts of crosslinking agent.

[0064] The outer LSZH sheath 7 is embedded with two reinforcing FRP members 8, and the outer LSZH sheath 7 is provided with peeling protrusions 10.

[0065] In this embodiment, the indoor micro-tube optical cable achieves comprehensive performance protection and construction adaptability through a multi-layered synergistic design: the inner LSZH sheath 3 uses an oil-resistant, low-smoke, halogen-free material, which effectively blocks fiber grease seepage and prevents the outer low-smoke, halogen-free material from swelling and deforming due to contact with fiber grease, ensuring the integrity of the sheath structure. Furthermore, the oil-resistant, low-smoke, halogen-free material provides comprehensive performance in terms of resistance to oil grease corrosion, low smoke release, halogen-free environmental protection, and high flame retardancy, significantly improving the optical cable's adaptability to complex environments such as oil, humidity, and high temperatures. It also enhances fire safety protection and effectively extends the long-term stable service life of the optical cable. The filling layer 11 provides waterproof sealing, moisture barrier, or structural buffering. Enhanced functionality; aramid yarn 4 serves as the core mechanical protective layer, significantly improving the tensile and impact resistance of the optical cable; tear cord 5 provides convenient assistance for peeling the outer sheath, simplifying construction operations; the outer LSZH sheath 7 is made of high flame-retardant, low-smoke, halogen-free material with an oxygen index ≥40%, enabling low-smoke and halogen-free release in fire scenarios, meeting stringent fire safety requirements; water-blocking tape 6 forms a longitudinal waterproof barrier, preventing moisture from spreading along the interior of the optical cable; reinforcing member 8 further strengthens the overall tensile and compressive strength of the optical cable, avoiding structural damage during construction or use; the stripping protrusions 10 on the outer LSZH sheath 7 facilitate precise positioning of the stripping location during construction and assist in optical cable identification. The synergistic effect of these multi-layered protective structures gives the optical cable core characteristics such as oil resistance, waterproofing, high flame retardancy, and ease of construction, making it suitable for various applications including 5G base stations, data centers, and industrial workshops.

[0066] The maximum permissible working tensile force of the indoor micro-tube type optical cable in Example 1 is 1320 N, and the flattening strength is 1200 N / 100 mm.

[0067] Example 2

[0068] A schematic diagram of an indoor micro-tube optical cable is shown below. Figure 2 As shown, the device includes a microtube bundle 1, aramid yarn 4, tear cord 5, and an outer LSZH sheath 7. The outer LSZH sheath 7 is disposed on the outside of the microtube bundle 1 and the tear cord 5. The aramid yarn 4 is filled between the microtube bundle 1 and the outer LSZH sheath 7. The outer LSZH sheath 7 is made of a low-smoke halogen-free material with an oxygen index ≥40%. The low-smoke halogen-free material includes the following components by mass percentage: 20% blended EVA, 15% ethylene-octene copolymer, 17% bimodal linear low-density polyethylene, 8% maleic anhydride-grafted PE, 30% aluminum hydroxide and magnesium hydroxide (mass ratio 1:1), 6% organosilicon charring agent, 2% melamine, and 2% phosphate ester.

[0069] The micro-tube 1 includes an optical fiber 2, a filling layer 11 and an inner LSZH sheath 3. The inner LSZH sheath 3 is disposed on the outside of the optical fiber 2, and the filling layer 11 is filled between the optical fiber 2 and the inner LSZH sheath 3.

[0070] The filling layer is made of aramid yarn, and the inner sheath is made of flame-retardant, low-smoke, halogen-free material with a Shore hardness of 60 HD.

[0071] The indoor micro-tube type optical cable is provided with a central reinforcing member FRP 9 at its center. Multiple sets of micro-tubes 1 are spirally twisted to wrap the central reinforcing member FRP 9, with a twisting pitch of 2 m.

[0072] In this embodiment, the aramid yarn 4 further enhances the tensile strength of the micro-tube 1, providing precise mechanical protection for the micro-tube and internal optical fibers. The central reinforcing member FRP 9 is located at the optical cable axis, which not only significantly improves the overall anti-flattening performance and tensile strength of the optical cable, but also plays a structural support role during the stranding of multiple micro-tubes, preventing deformation caused by compression between micro-tubes, thereby protecting the stable attenuation performance of optical fiber transmission. The inner LSZH sheath 3 and the outer LSZH sheath 7 form a double-layer protection system, with the inner layer focusing on protecting the internal structure of the micro-tube and the outer layer strengthening the overall mechanical properties of the optical cable. Together with the central reinforcing member and aramid yarn, the optical cable performs particularly well in terms of tensile and bending resistance, effectively resisting external force damage during construction or daily use, and ensuring long-term stable transmission of optical fiber signals.

[0073] The maximum permissible working tensile force of the indoor micro-tube type optical cable in Example 2 is 660 N, and the flattening strength is 1000 N / 100 mm.

[0074] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art should understand that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An indoor micro-tube type optical cable, characterized in that, It includes a microtube bundle, aramid yarn, tear cord and outer sheath. The outer sheath is disposed on the outside of the microtube bundle and tear cord. The aramid yarn is filled between the microtube bundle and the outer sheath. The outer sheath is made of a low-smoke halogen-free material with an oxygen index ≥40%. The micro-tube includes an optical fiber, a filling layer, and an inner sheath. The inner sheath is disposed on the outside of the optical fiber, and the filling layer is filled between the optical fiber and the inner sheath. The filling layer is made of fiber paste, water-resistant yarn, or aramid yarn. When the filling layer is made of fiber paste, the inner sheath is made of an oil-resistant, low-smoke, halogen-free material. The oil-resistant, low-smoke, halogen-free material comprises the following components by weight: 52-60 parts of blended EVA, 23-35 parts of palygorskite fiber, 50-75 parts of flame retardant, 16.5-20.3 parts of graphene oxide, 5-17 parts of ethylene propylene rubber, and 6.85-10.8 parts of crosslinking agent. When the filling layer is made of water-resistant yarn or aramid yarn, the inner sheath is made of a flame-retardant, low-smoke, halogen-free material with a Shore hardness of 54-62 HD.

2. The indoor micro-tube optical cable according to claim 1, characterized in that, The low-smoke halogen-free material comprises the following components by weight percentage: 12-30% blended EVA, 5-20% ethylene-octene copolymer, 8-30% bimodal linear low-density polyethylene, 5-15% maleic anhydride-grafted PE, 20-50% flame retardant, 2-10% organosilicon charring agent, 1-3% nitrogen-based synergist, and 1-3% phosphate ester.

3. The indoor micro-tube optical cable according to claim 1 or 2, characterized in that, The blended EVA comprises ethylene-vinyl acetate copolymers with a VA content of 5-40 wt% in a mass ratio of (60-80):(20-40) and blends of ethylene-vinyl acetate copolymers with a VA content higher than 40%.

4. The indoor micro-tube optical cable according to claim 1, characterized in that, The flame retardant in the oil-resistant, low-smoke, halogen-free material is aluminum hydroxide or magnesium hydroxide.

5. The indoor micro-tube optical cable according to claim 1, characterized in that, The outer diameter of the inner sheath is 0.9-1.5 mm, and the wall thickness is 0.1-0.15 mm.

6. The indoor micro-tube optical cable according to claim 1, characterized in that, A water-blocking strip is provided between the outer side of the microtube and the tear rope and the outer sheath.

7. The indoor micro-tube optical cable according to claim 1, characterized in that, The indoor micro-tube optical cable has a central reinforcement member at its center.

8. The indoor micro-tube optical cable according to claim 7, characterized in that, The central reinforcement is made of glass fiber reinforced plastic.

9. The indoor micro-tube optical cable according to claim 1, characterized in that, The outer sheath is embedded with a reinforcing element.

10. The indoor micro-tube optical cable according to claim 1, characterized in that, The outer sheath is provided with peeling protrusions or color stripes.

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