A multi-core microcable and a method of manufacturing the same

Abstract

This invention belongs to the field of optical fiber communication technology and discloses a multi-core microcable and its manufacturing method. The multi-core microcable includes a cable core, an inner sheath, and an outer sheath. The cable core includes multiple optical units arranged in a twisted configuration. The inner sheath covers the cable core and includes a first friction-reducing layer that contacts the cable core. The outer sheath covers the inner sheath and includes a support layer and a second friction-reducing layer, which is exposed and covers the support layer. By contacting the first friction-reducing layer with the cable core, the cable core can slide freely relative to the first friction-reducing layer, reducing the micro-bending loss of the optical units caused by the outer and inner sheaths, thus improving the transmission stability of the multi-core microcable. The multi-core microcable of this invention can be laid over long distances using air-blowing. It can also be laid in curved microtubes using air-blowing. During air-blowing, the micro-bending loss of the multi-core microcable is reduced, resulting in high transmission stability, while the propulsion speed of the high-pressure airflow is not slowed down, thus improving air-blowing efficiency.

Description

Technical Field

[0001] This invention relates to the field of optical fiber communication technology, and in particular to a multi-core microcable and its manufacturing method. Background Technology

[0002] Currently, the mainstream method for laying multi-core microcables is air blowing or traction. Air blowing refers to using the thrust generated by the high-pressure airflow flowing at high speed in the microtube to act on the surface of the outer sheath of the multi-core microcable, thus propelling the microcable forward in the microtube.

[0003] In existing multi-core microcables, the outer sheath has a relatively high coefficient of friction, resulting in greater air-blowing resistance and slower air-blowing speed during long-distance air-blowing, thus reducing air-blowing efficiency. Furthermore, when the multi-core microcable passes through bends in microtubes, the tensile or compressive deformation of the outer sheath is transmitted to the cable core and then to the internal optical fibers, causing micro-bending loss and affecting the transmission stability of the optical fibers. Additionally, during air-blowing, the microcable may rotate around its own axis, and the torque of the outer sheath is directly transmitted to the cable core, causing it to twist and then to the internal optical fibers. The mutual compression between the internal optical fibers also contributes to micro-bending loss. When a large micro-bending loss value is detected, the propulsion speed of the high-pressure airflow is slowed down to reduce micro-bending loss; however, slowing down the propulsion speed of the high-pressure airflow reduces air-blowing efficiency. Therefore, there is an urgent need for a multi-core microcable and its manufacturing method to solve the above-mentioned technical problems. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-core microcable and its manufacturing method. The multi-core microcable can be laid over long distances by air blowing. The multi-core microcable can also be laid in curved microtubes by air blowing. During air blowing, the micro-bending loss of the multi-core microcable can be reduced, resulting in higher transmission stability. At the same time, it does not need to slow down the propulsion speed of the high-pressure airflow, thus improving the air blowing efficiency.

[0005] To achieve this objective, the present invention adopts the following technical solution: On the one hand, a multi-core microcable is provided, comprising: The cable core includes multiple optical units, which are twisted together. An inner sheath layer is wrapped around the cable core; the inner sheath layer includes a first friction-reducing layer that is in contact with the cable core. An outer sheath covers the inner sheath layer. The outer sheath includes a support layer and a second friction-reducing layer, with the second friction-reducing layer covering the support layer and exposed.

[0006] In some possible implementations, each optical unit includes an optical fiber and a loose tube, the optical fiber being located inside the loose tube, the gap between the optical fiber and the loose tube being filled with fiber grease, and the outer wall of the loose tube being provided with a third friction-reducing layer that can contact the first friction-reducing layer.

[0007] In some possible implementations, the third friction-reducing layer is made of silicone-modified polyolefin or fluorine-modified polyolefin; and / or, The optical fiber is provided in multiple forms, and the multiple optical fibers are twisted together.

[0008] In some possible implementations, the outer sheath further includes an adhesive layer that contacts the inner sheath layer, and the support layer is located between the adhesive layer and the second friction-reducing layer.

[0009] In some possible implementations, the support layer is made of polyethylene, and the adhesive layer is made of maleic anhydride-grafted polyethylene; and / or, The adhesive layer, the support layer, and the second friction-reducing layer are co-extruded into the inner sleeve layer.

[0010] In some possible implementations, the second friction-reducing layer is uniformly filled with a plurality of nanoparticles configured to contact the inner wall of the microtube.

[0011] In some possible implementations, the nanoparticles are made of silicon dioxide, and the second friction-reducing layer is made of silicone / fluorine blended modified polyethylene.

[0012] In some possible implementations, the inner sheath further includes a first water-blocking unit covering the first friction-reducing layer, and the outer sheath covering the first water-blocking unit. The first water-blocking unit includes at least one of water-blocking yarn and water-blocking tape; and / or, The cable core also includes a reinforcing member, and the plurality of optical units are stranded together and located outside the reinforcing member; the cable core also includes a second water-blocking unit, which fills the gap between the first friction-reducing layer and the reinforcing member, and the second water-blocking unit is water-blocking yarn.

[0013] On the other hand, a method for manufacturing a multi-core microcable is provided, applicable to the multi-core microcable described in any of the above embodiments, comprising: Multiple optical units are twisted together to form a cable core; An inner sheath is wrapped around the cable core, and the first anti-friction layer of the inner sheath is in contact with the cable core. An outer sheath is wrapped around the inner sheath, exposing the second friction-reducing layer.

[0014] In some possible implementations, covering the outer sheath outside the inner sheath and exposing the second friction-reducing layer includes: Nanoparticles are mixed and stirred with silicone / fluorine blended modified polyethylene particles to form a mixture; the mixture is fed into a twin-screw extruder, where the silicone / fluorine blended modified polyethylene particles are melted to form a melt, and the nanoparticles are dispersed in the melt; the melt is cooled and pelletized to obtain co-extruded particles; The particles for preparing the adhesive layer, the particles for preparing the support layer, and the co-extruded particles are co-extruded into the inner sleeve layer to form the adhesive layer, the support layer, and the second friction-reducing layer filled with a plurality of nanoparticles, such that the adhesive layer is in contact with the inner sleeve layer and the second friction-reducing layer is exposed.

[0015] The beneficial effects of this invention are: The multi-core microcable provided by this invention includes a cable core, an inner sheath, and an outer sheath. The cable core includes multiple optical units. The inner sheath includes a first anti-friction layer. Contacting the cable core with the first anti-friction layer reduces interlayer friction, allowing the cable core to slide freely relative to the first anti-friction layer. When the multi-core microcable passes through a bend in a microtube, the free sliding of the cable core relative to the first anti-friction layer reduces micro-bending losses of the outer and inner sheaths on the optical units. When the multi-core microcable rotates around its own axis, the free sliding of the cable core relative to the first anti-friction layer reduces the possibility of the optical units twisting with the inner and outer sheaths, further reducing micro-bending losses and improving transmission stability. Therefore, the multi-core microcable of this invention can be laid over long distances using air-blowing. It can also be laid in curved microtubes using air-blowing. During air-blowing, micro-bending losses are reduced, ensuring high transmission stability, while simultaneously improving air-blowing efficiency without slowing down the propulsion speed of the high-pressure airflow. Building upon this, the second friction-reducing layer of the outer sheath is exposed, allowing it to contact the inner wall of the microtube during air blowing. This reduces friction between the outer sheath and the microtube, lowers air blowing resistance, and further improves air blowing efficiency. The second friction-reducing layer is then wrapped around the support layer, which serves as the core load-bearing layer of the outer sheath, providing mechanical protection against compression, tension, and impact. This enhances the structural stability of the multi-core microcable during air blowing installation and use. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of the multi-core microcable provided by the present invention; Figure 2 This is a cross-sectional view of the outer sheath involved in this invention.

[0017] In the picture: 1. Cable core; 11. Optical unit; 111. Optical fiber; 112. Loose tube; 113. Fiber grease; 12. Reinforcing member; 13. Second water-blocking unit; 2. Inner sheath; 21. First friction-reducing layer; 22. First water-blocking unit; 3. Outer sheath; 31. Support layer; 32. Second friction-reducing layer; 33. Adhesive layer; 4. Filler rope. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0020] In the description of this invention, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 and Figure 2As shown, this invention provides a multi-core microcable that can be applied to micro-tube and micro-cable systems in FTTx (Fiber To The x, where x represents the destination of the fiber optic line), data centers, and 5G access networks. The multi-core microcable includes a cable core 1, an inner sheath 2, and an outer sheath 3. The cable core 1 includes multiple optical units 11, which are twisted together. The inner sheath 2 covers the cable core 1 and includes a first friction-reducing layer 21 that contacts the cable core 1. The outer sheath 3 covers the inner sheath 2 and includes a support layer 31 and a second friction-reducing layer 32, which covers the support layer 31 and is exposed.

[0023] The inner sheath 2 includes a first anti-friction layer 21. The first anti-friction layer 21 contacts the cable core 1, reducing interlayer friction and allowing the cable core 1 to slide freely relative to the first anti-friction layer 21. When the multi-core microcable passes through a bend in the microtube, the free sliding of the cable core 1 relative to the first anti-friction layer 21, i.e., the free sliding of the optical unit 11 relative to the first anti-friction layer 21, reduces the micro-bending loss of the optical unit 11 caused by the outer sheath 3 and the inner sheath 2. When the multi-core microcable rotates around its own axis, the free sliding of the cable core 1 relative to the first anti-friction layer 21 reduces the possibility of the optical unit 11 twisting with the inner sheath 2 and the outer sheath 3, further reducing the micro-bending loss of the optical unit 11 caused by the outer sheath 3 and the inner sheath 2, resulting in higher transmission stability for the multi-core microcable. Therefore, the multi-core microcable of the present invention can be laid over long distances by air blowing. The multi-core microcable can also be laid in curved microtubes by air blowing. During air blowing, the micro-bending loss of the multi-core microcable can be reduced, resulting in higher transmission stability, while not requiring a slowdown in the propulsion speed of the high-pressure airflow, thus improving air blowing efficiency. Based on this, the second friction-reducing layer 32 of the outer sheath 3 is exposed. During air blowing, the second friction-reducing layer 32 contacts the inner wall of the microtube, reducing friction between the outer sheath 3 and the microtube, lowering air blowing resistance, ensuring smooth long-distance air blowing laying, and further improving air blowing efficiency. The second friction-reducing layer 32 is wrapped around the support layer 31. The support layer 31, as the core load-bearing layer of the outer sheath 3, provides mechanical protection against pressure, tension, and impact, improving the structural stability of the multi-core microcable during air blowing laying and use.

[0024] Optionally, each optical unit 11 includes an optical fiber 111 and a loose tube 112. The optical fiber 111 is located inside the loose tube 112. The gap between the optical fiber 111 and the loose tube 112 is filled with fiber grease 113. The outer wall of the loose tube 112 is provided with a third friction-reducing layer, which can contact the first friction-reducing layer 21. The third friction-reducing layer on the outer wall of the loose tube 112, which contacts the first friction-reducing layer 21, further reduces the interlayer friction between the optical unit 11 and the first friction-reducing layer 21, thereby reducing the micro-bending loss of the optical unit 11 caused by the outer sheath 3 and the inner sheath 2. Optionally, the third friction-reducing layer is coated on the outer wall of the loose tube 112. Filling the gap between the optical fiber 111 and the loose tube 112 with fiber grease 113 provides water resistance and moisture protection, and also protects the optical fiber 111, preventing damage caused by direct contact between the optical fiber 111 and the loose tube 112. Optionally, the wall thickness of the loose sleeve 112 is 0.25-0.35 mm.

[0025] Optionally, the third friction-reducing layer is made of silicone-modified polyolefin. This configuration results in a lower coefficient of friction and lower cost for the third friction-reducing layer. Alternatively, the third friction-reducing layer can be made of fluorine-modified polyolefin. This configuration also results in a lower coefficient of friction for the third friction-reducing layer. Optionally, multiple optical fibers 111 are provided, and the multiple optical fibers 111 are stranded together. This configuration allows the optical fibers 111 to move slightly within the loose tube 112. When the multi-core microcable is bent or twisted, the optical fibers 111 can slide slightly or adjust their position relative to the loose tube 112, avoiding local stress concentration that could lead to breakage of the optical fibers 111.

[0026] Optionally, the outer sheath 3 further includes an adhesive layer 33, which contacts the inner sheath 2, and a support layer 31 is located between the adhesive layer 33 and the second friction-reducing layer 32. This configuration allows the outer sheath 3 to contact the inner sheath 2 via the adhesive layer 33, increasing the adhesion between the second friction-reducing layer 32 and the support layer 31 and the inner sheath 2, improving the connection strength between the outer sheath 3 and the inner sheath 2, preventing the outer sheath 3 from detaching or shifting relative to the inner sheath 2, and ensuring the long-term use of the outer sheath 3.

[0027] Optionally, the support layer 31 is made of polyethylene. This design can withstand external pressure and tension during the microcable laying process, ensuring that the internal structure of the microcable is not damaged. Specifically, the density of polyethylene is 0.936-0.946 g / cm³. 3 It exhibits excellent impact resistance. Optionally, the adhesive layer 33 is made of maleic anhydride-grafted polyethylene. This configuration achieves high-strength bonding between the outer sheath 3 and the inner sheath 2, while ensuring a tight seal between them. Specifically, the grafting rate of the maleic anhydride-grafted polyethylene is controlled at 0.9%-1.3%, the melt index is 0.4-0.7 g / 10 min (190℃ / 2.16 kg), and the density is 0.922-0.931 g / cm³.3 It possesses relatively excellent polar bonding properties, with a density of 0.936-0.946 g / cm³. 3 The polyethylene has excellent compatibility, a peel strength of ≥220N / 25mm, no risk of delamination, and good melt flowability, making it suitable for co-extrusion and synchronous molding.

[0028] Optionally, the adhesive layer 33, the support layer 31, and the second friction-reducing layer 32 are co-extruded onto the inner sheath layer 2. This arrangement ensures a tight bond between the adhesive layer 33 and the support layer 31, as well as between the support layer 31 and the second friction-reducing layer 32, resulting in a strong interlayer bond. It also ensures close contact between the adhesive layer 33 and the inner sheath layer 2, guaranteeing the air-blown laying performance, mechanical strength, and long-term service life of the multi-core microcable. Optionally, the thickness of the adhesive layer 33 accounts for 12%-15% of the total thickness of the outer sheath 3, the thickness of the support layer 31 accounts for 65%-70% of the total thickness of the outer sheath 3, and the thickness of the second friction-reducing layer 32 accounts for 15%-18% of the total thickness of the outer sheath 3.

[0029] Optionally, the second friction-reducing layer 32 is uniformly filled with a plurality of nanoparticles, which are configured to contact the inner wall of the microtube. It is understood that "uniformly filled with a plurality of nanoparticles" in the second friction-reducing layer 32 means that the nanoparticles fill the interior of the second friction-reducing layer 32 and cover its outer periphery, and that the nanoparticles are uniformly distributed. The uniform filling of the second friction-reducing layer 32 with nanoparticles allows the nanoparticles to contact the inner wall of the microtube, resulting in a very low coefficient of friction on the outer surface of the outer sheath 3, thus improving wear resistance. During processing, the particles used to prepare the second friction-reducing layer 32 can be thoroughly mixed with the nanoparticles to form a second friction-reducing layer 32 uniformly filled with a plurality of nanoparticles, facilitating processing. Furthermore, the uniform distribution of the nanoparticles improves the overall mechanical properties of the second friction-reducing layer 32 and the nanoparticles. Further, the coefficient of friction of the second friction-reducing layer 32 uniformly filled with a plurality of nanoparticles is 0.08-0.15.

[0030] Optionally, the nanoparticles are made of silicon dioxide, and the second friction-reducing layer 32 is made of silicone / fluorine blended modified polyethylene. This configuration allows the outer surface of the outer sheath 3 to have a very low coefficient of friction, while improving the wear resistance, aging resistance, and environmental corrosion resistance of the outer sheath 3, thus meeting the low-resistance requirements of air-blown laying.

[0031] Optionally, the inner sheath 2 further includes a first water-blocking unit 22, which covers the first friction-reducing layer 21, and the outer sheath 3 covers the first water-blocking unit 22. The first water-blocking unit 22 includes at least one of water-blocking yarn and water-blocking tape. That is, the first water-blocking unit 22 includes water-blocking yarn, or the first water-blocking unit 22 includes water-blocking tape, or, to improve the water-blocking effect, the first water-blocking unit 22 includes both water-blocking yarn and water-blocking tape. By setting the first water-blocking unit 22 between the first friction-reducing layer 21 and the outer sheath 3, it serves to block water. The first water-blocking unit 22 includes at least one of water-blocking yarn and water-blocking tape, making the first water-blocking unit 22 a dry water-blocking material, without grease, environmentally friendly and easy to splice, and making the multi-core micro cable lighter in weight. Since both the water-blocking yarn and the water-blocking tape are flexible materials, the flexibility of the multi-core micro cable is improved, thereby improving the throughput of the multi-core micro cable to adapt to complex and curved microtubes and to be repeatedly laid in microtubes.

[0032] Optionally, the first friction-reducing layer 21 is a strip structure that wraps around the cable core 1, and the material of the strip structure is PTFE (polytetrafluoroethylene) modified polyolefin. This arrangement facilitates the wrapping of the first friction-reducing layer 21 around the cable core 1, improves the ease of operation, and allows the cable core 1 to slide freely relative to the first friction-reducing layer 21.

[0033] Optionally, the cable core 1 also includes a reinforcing member 12, with multiple optical units 11 stranded and located outside the reinforcing member 12. By setting the reinforcing member 12 and stranding the multiple optical units 11 outside the reinforcing member 12, the multi-core microcable's resistance to external forces such as tension and lateral pressure can be improved, ensuring stranding stability. Optionally, the multiple optical units 11 are SZ stranded and located outside the reinforcing member 12. This arrangement reduces the space occupied by the multiple optical units 11, thereby reducing the outer diameter of the multi-core microcable and improving the space utilization of the microtube. SZ stranding refers to the formation using the SZ stranding process, which is a mature technology in related fields. Optionally, the reinforcing member 12 is located at the center of the inner sheath 2.

[0034] Optionally, the cable core 1 further includes a second water-blocking unit 13, which fills the gap between the first friction-reducing layer 21 and the reinforcing member 12. The second water-blocking unit 13 is made of water-blocking yarn. By setting the second water-blocking unit 13, it serves to block water. The second water-blocking unit 13 is made of water-blocking yarn, making it a dry water-blocking material, free of grease, environmentally friendly, and easy to splice. It also makes the multi-core microcable lighter. Since the water-blocking yarn is a flexible material, it improves the flexibility of the multi-core microcable, thereby improving its throughput, allowing it to adapt to complex and curved microtubes and be repeatedly laid within them. In addition, the second water-blocking unit 13, being made of water-blocking yarn, allows the optical unit 11 to slide freely in the gap between the first friction-reducing layer 21 and the reinforcing member 12.

[0035] Optionally, the reinforcing member 12 is an FRP (fiber-reinforced plastic) rod or a high-strength aramid multifilament. Using an FRP rod provides higher tensile strength. Optionally, the FRP rod has a diameter of 0.8-1.2 mm. Using a high-strength aramid multifilament improves the flexibility of the multi-core microcable. Alternatively, the reinforcing member 12 can also be made of glass fiber.

[0036] Optionally, the loose sleeve 112 is made of high-modulus PBT (polybutylene terephthalate) or high-modulus COPA (copolyamide). Using high-modulus PBT gives the loose sleeve 112 higher rigidity and resistance to lateral pressure. Using high-modulus COPA improves the flexibility of the loose sleeve 112, resulting in lower internal stress during bending or winding, and reducing the likelihood of plastic deformation or cracking.

[0037] Optionally, the multi-core microcable also includes a filler rope 4, which is twisted with multiple optical units 11 in an SZ configuration and located outside the reinforcing member 12. By providing the filler rope 4 to fill the gap between the first anti-friction layer 21 and the reinforcing member 12, the roundness of the multi-core microcable can be improved, ensuring smooth high-pressure airflow and uniform thrust, so as to achieve stable long-distance laying.

[0038] Optionally, in one embodiment, the reinforcing member 12 is an FRP rod; four optical units 11 are provided, and twelve optical fibers 111 are provided in each optical unit 11; the loose tube 112 is made of high modulus PBT, and a third friction-reducing layer is provided on the outer wall of the loose tube 112, which can contact the first friction-reducing layer 21; the first friction-reducing layer 21 is a strip structure, which is wrapped around the cable core 1 and wrapped in one layer, with a thickness of 0.2 mm, and the material of the strip structure is PTFE modified polyolefin; the first water-blocking unit 22 includes water-blocking yarn and water-blocking tape; the adhesive layer 33, the support layer 31, and the second friction-reducing layer 32 are co-extruded in the inner sheath layer 2, the total thickness of the outer sheath 3 is 0.6 mm, the friction coefficient of the second friction-reducing layer 32, which is uniformly filled with multiple nanoparticles, is 0.11, the outer diameter of the multi-core microcable is 5.4 mm, the multi-core microcable is a 48-core low-friction multi-core microcable, and it is suitable for microtubes with a diameter of 10 mm.

[0039] Optionally, in another embodiment, the reinforcing member 12 is a high-strength aramid multifilament; there are two optical units 11, and each optical unit 11 has twelve optical fibers 111; the first friction-reducing layer 21 is a strip structure, which is wrapped around the cable core 1, and the material of the strip structure is PTFE modified polyolefin; the friction coefficient of the second friction-reducing layer 32, which is uniformly filled with multiple nanoparticles, is 0.12; the outer diameter of the multi-core microcable is 4.2 mm; the multi-core microcable is a 24-core lightweight multi-core microcable, suitable for Φ7 mm microtubes.

[0040] This invention also provides a method for manufacturing a multi-core microcable, applicable to the aforementioned multi-core microcable, comprising: Multiple optical units 11 are twisted together to form cable core 1; The inner sheath 2 is wrapped around the cable core 1, and the first anti-friction layer 21 of the inner sheath 2 is in contact with the cable core 1. The inner sheath 2 is covered by the outer sheath 3, and the second friction-reducing layer 32 is exposed.

[0041] The multi-core microcable manufactured by this method can be laid over long distances by air blowing. The multi-core microcable can also be laid in curved microtubes by air blowing. During air blowing, the micro-bending loss of the multi-core microcable is minimized, resulting in high transmission stability. At the same time, there is no need to slow down the propulsion speed of the high-pressure airflow, which can improve the air blowing efficiency.

[0042] Optionally, covering the inner sheath 2 with the outer sheath 3, and exposing the second friction-reducing layer 32, includes: Nanoparticles are mixed and stirred with silicone / fluorine blended modified polyethylene particles to form a mixture; the mixture is fed into a twin-screw extruder, where the silicone / fluorine blended modified polyethylene particles are melted to form a melt, and the nanoparticles are dispersed in the melt; the melt is cooled and pelletized to obtain co-extruded particles; The particles for preparing the adhesive layer 33, the particles for preparing the support layer 31, and the co-extruded particles are co-extruded into the inner sleeve layer 2 to form the adhesive layer 33, the support layer 31, and the second friction-reducing layer 32 filled with multiple nanoparticles, so that the adhesive layer 33 is in contact with the inner sleeve layer 2 and the second friction-reducing layer 32 is exposed.

[0043] By mixing and stirring nanoparticles with silicone / fluorine blended modified polyethylene particles, and then melting the silicone / fluorine blended modified polyethylene particles into a melt using a twin-screw extruder, the nanoparticles can be uniformly dispersed in the melt, avoiding agglomeration that would cause the outer surface of the second friction-reducing layer 32 filled with multiple nanoparticles to become rough. This facilitates the subsequent formation of the second friction-reducing layer 32 uniformly filled with multiple nanoparticles.

[0044] Optionally, before co-extrudeing the particles for preparing the adhesive layer 33, the particles for preparing the support layer 31, and the co-extruded particles into the inner sleeve layer 2, the inner sleeve layer 2 is preheated using an infrared preheating device. This setting can remove moisture from the surface of the inner sleeve layer 2 and ensure the bonding effect.

[0045] Optionally, silicone-modified polyethylene and fluorine-modified polyethylene are blended in a 6:4 ratio to form silicone / fluorine blended modified polyethylene particles. Nanoparticles with a particle size of 50-80nm and made of silica are added at a rate of 4%-7% to form a mixture. After blending, the melt index is 0.5-0.9g / 10min (190℃ / 2.16kg), so that the outer surface friction coefficient of the outer sheath 3 is ≤0.13 and the wear resistance is ≤4mg (1000g load).

[0046] Before mixing and stirring the nanoparticles with the silicone / fluorine blend modified polyethylene particles, the process includes surface activation of the nanoparticles. This arrangement enhances the compatibility of the nanoparticles with the silicone / fluorine blend modified polyethylene particles. Specifically, surface activation of the nanoparticles includes mixing the nanoparticles with a silane coupling agent.

[0047] Optionally, the particles for preparing the adhesive layer 33, the particles for preparing the support layer 31, and the co-extruded particles are co-extruded into the inner sleeve layer 2 to form a co-extruded structure. The co-extruded structure is then shaped using a vacuum sizing sleeve to form the adhesive layer 33, the support layer 31, and the second friction-reducing layer 32 filled with multiple nanoparticles. Shaping the co-extruded structure using a vacuum sizing sleeve ensures the accuracy of the outer diameter of the outer sleeve 3, guarantees roundness, ensures smooth high-pressure airflow and uniform thrust, and enables stable long-distance laying.

[0048] 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 can make other variations or modifications 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. A multi-core microcable, characterized in that, include: The cable core (1) includes multiple optical units (11), which are twisted together. Inner sheath (2), the inner sheath (2) covers the outside of the cable core (1); the inner sheath (2) includes a first friction-reducing layer (21), the first friction-reducing layer (21) is in contact with the cable core (1); The outer sheath (3) covers the inner sheath (2). The outer sheath (3) includes a support layer (31) and a second friction-reducing layer (32). The second friction-reducing layer (32) covers the support layer (31) and is exposed.

2. The multi-core microcable according to claim 1, characterized in that, Each optical unit (11) includes an optical fiber (111) and a loose tube (112). The optical fiber (111) is located inside the loose tube (112). The gap between the optical fiber (111) and the loose tube (112) is filled with fiber grease (113). The outer wall of the loose tube (112) is provided with a third friction-reducing layer, which can contact the first friction-reducing layer (21).

3. The multi-core microcable according to claim 2, characterized in that, The third friction-reducing layer is made of silicone-modified polyolefin or fluorine-modified polyolefin; and / or, The optical fiber (111) is provided in multiple forms, and the multiple optical fibers (111) are twisted together.

4. The multi-core microcable according to claim 1, characterized in that, The outer sheath (3) also includes an adhesive layer (33) that contacts the inner sheath (2), and the support layer (31) is located between the adhesive layer (33) and the second friction-reducing layer (32).

5. The multi-core microcable according to claim 4, characterized in that, The support layer (31) is made of polyethylene, and the adhesive layer (33) is made of maleic anhydride-grafted polyethylene; and / or, The adhesive layer (33), the support layer (31), and the second friction-reducing layer (32) are co-extruded in the inner sleeve layer (2).

6. The multi-core microcable according to claim 1, characterized in that, The second friction-reducing layer (32) is uniformly filled with a plurality of nanoparticles, which are configured to contact the inner wall of the microtube.

7. The multi-core microcable according to claim 6, characterized in that, The nanoparticles are made of silicon dioxide, and the second friction-reducing layer (32) is made of silicone / fluorine blended modified polyethylene.

8. The multi-core microcable according to claim 1, characterized in that, The inner sleeve (2) further includes a first water-blocking unit (22), which covers the first friction-reducing layer (21). The outer sheath (3) covers the first water-blocking unit (22). The first water-blocking unit (22) includes at least one of water-blocking yarn and water-blocking tape; and / or, The cable core (1) also includes a reinforcing member (12), and a plurality of optical units (11) are twisted together and located outside the reinforcing member (12); the cable core (1) also includes a second water-blocking unit (13), which fills the gap between the first friction-reducing layer (21) and the reinforcing member (12), and the second water-blocking unit (13) is a water-blocking yarn.

9. A method for manufacturing a multi-core microcable, applied to the multi-core microcable according to any one of claims 1-8, characterized in that, include: Multiple optical units (11) are twisted together to form a cable core (1). The inner sheath (2) is wrapped around the cable core (1), and the first anti-friction layer (21) of the inner sheath (2) is in contact with the cable core (1); The inner sleeve (2) is covered by an outer sheath (3), and the second friction-reducing layer (32) is exposed.

10. The method for manufacturing a multi-core microcable according to claim 9, characterized in that, Covering the outer sheath (3) with the inner sheath (2) and exposing the second friction-reducing layer (32) includes: Nanoparticles are mixed and stirred with silicone / fluorine blended modified polyethylene particles to form a mixture; the mixture is fed into a twin-screw extruder, where the silicone / fluorine blended modified polyethylene particles are melted to form a melt, and the nanoparticles are dispersed in the melt; the melt is cooled and pelletized to obtain co-extruded particles; The particles for preparing the adhesive layer (33), the particles for preparing the support layer (31), and the co-extruded particles are co-extruded into the inner sleeve layer (2) to form the adhesive layer (33), the support layer (31), and the second friction-reducing layer (32) filled with a plurality of nanoparticles, so that the adhesive layer (33) is in contact with the inner sleeve layer (2) and the second friction-reducing layer (32) is exposed.

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