A multi-layer air blown microcable and a method of manufacturing the same

Abstract

The application discloses a kind of multilayer air blowing microcable and preparation method thereof, belong to optical cable preparation technical field, including central reinforcing member, multiple optical units are twisted and arranged on the outer periphery of the central reinforcing member, the optical unit includes optical fiber element and sleeve pipe set on the outer periphery of optical fiber element, sleeve pipe includes first liquid crystal polymer layer, first shear resistance layer and first protective layer sequentially arranged from inside to outside;And the outer periphery of multiple optical units is also provided with outer sheath.The multilayer air blowing microcable in the application sets sleeve pipe as the three-layer structure of first liquid crystal polymer layer, first shear resistance layer and first protective layer, and the first liquid crystal polymer layer has strong impact resistance, the first shear resistance layer has good absorption capacity, the first protective layer has the ability to disperse impact everywhere, avoids the problem that external impact force penetrates cable, greatly improves the impact resistance of optical cable without greatly changing the quality and diameter of optical cable.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical cable preparation, and particularly relates to a multi-layer air-blow microcable and a preparation method thereof. BACKGROUND

[0002] With the acceleration of FTTH construction process in China, the optical fiber and cable infrastructure is increasingly improved. However, the rapid growth of traffic and the acceleration of 5G commercialization make the demand for network capacity continue to increase. In order to increase the capacity of the network, the number of optical fibers in the optical cable needs to be increased. With the improvement of various underground line facilities in the city, the city pipeline resources are also increasingly strained, resulting in the requirement that the diameter and weight of the optical cable are as small as possible when the optical cable is laid in the existing pipeline to reduce the occupation of pipeline resources.

[0003] The air-blow microcable has small structure size, light weight, large fiber density and good bending performance, and is suitable for overhead and pipeline laying. The application of the air-blow microcable in the existing optical cable pipeline can well meet the existing network expansion construction demand. However, due to the small structure size, light weight and good bending performance of the air-blow microcable itself, the diameter of the central reinforcing member of the air-blow optical cable is small, and the thickness of the sleeve and the thickness of the protective layer are thin, so that the tensile resistance, lateral pressure resistance and impact resistance of the air-blow microcable are weak, and the air-blow microcable is more likely to be damaged during installation, transportation or construction. SUMMARY

[0004] In view of one or more of the above defects or improvement needs of the prior art, the application provides a multi-layer air-blow microcable to solve the problem that the existing air-blow microcable has weak tensile resistance, lateral pressure resistance and impact resistance under small structure size.

[0005] To achieve the above-mentioned purpose, the application provides a preparation method of a multi-layer air-blow microcable, which comprises the following steps:

[0006] S1, pulling an optical fiber element;

[0007] S2, synchronously extruding a first liquid crystal polymer layer, a first shear-resistant layer and a first protective layer on the outer periphery of the optical fiber element to obtain an optical unit; wherein the extrusion temperature of the first liquid crystal polymer layer, the first shear-resistant layer and the first protective layer is 220-230 DEG C;

[0008] S3, pulling a central reinforcing member, and twisting a plurality of optical units around the central reinforcing member as the center;

[0009] S4, synchronously extruding a second liquid crystal polymer layer, a second shear-resistant layer and a second protective layer on the outer periphery of the plurality of optical units to obtain a multi-layer air-blow microcable.

[0010] As a further improvement of the present application, the first liquid crystal polymer layer in step S2 is TLCP, the first shear resistant layer is D3O, and the first protective layer is PP.

[0011] As a further improvement of the present application, POE-g-GMA is added in the extrusion material of the first shear resistant layer in step S2, and the POE-g-GMA accounts for 2-3wt% of the first shear resistant layer.

[0012] As a further improvement of the present application, ethylene glycol phenyl ether is added in the extrusion material of the first liquid crystal polymer layer in step S2, and the ethylene glycol phenyl ether accounts for 1-5wt% of the first liquid crystal polymer layer.

[0013] As a further improvement of the present application, plasticizer is added in the extrusion material of the first liquid crystal polymer layer in step S2, and the plasticizer accounts for 5-10wt% of the first liquid crystal polymer layer.

[0014] As a further improvement of the present application, step S1 further comprises arranging a first water resistant layer on the outer periphery of the optical fiber element; and step S3 further comprises arranging a second water resistant layer on the outer periphery of the twisted structure of the plurality of optical units and the central strength member.

[0015] The present application further comprises a multi-layer air-blow micro-cable, which comprises:

[0016] a central strength member;

[0017] a plurality of optical units, the plurality of optical units being arranged in a twisted manner on the outer periphery of the central strength member;

[0018] each of the plurality of optical units comprises an optical fiber element, and a sleeve is arranged on the outer periphery of the optical fiber element; the sleeve comprises, from inside to outside, a first liquid crystal polymer layer, a first shear resistant layer, and a first protective layer;

[0019] an outer sheath, which is arranged on the outer periphery of the plurality of optical units.

[0020] As a further improvement of the present application, the outer sheath comprises, from inside to outside, a second liquid crystal polymer layer, a second shear resistant layer, and a second protective layer.

[0021] As a further improvement of the present application, the thickness ratio of the first liquid crystal polymer layer, the first shear resistant layer, and the first protective layer in the sleeve is 2:1:1.

[0022] As a further improvement of the present application, the first liquid crystal polymer layer and / or the second liquid crystal polymer layer each comprises one of a lyotropic liquid crystal polymer, a thermotropic liquid crystal polymer, and a piezotropic liquid crystal polymer; and the first shear resistant layer and / or the second shear resistant layer each comprises a shear thickening fluid.

[0023] The above technical features can be combined with each other as long as they do not conflict with each other.

[0024] Overall, compared with the prior art, the above technical solutions conceived by the present application have the following beneficial effects:

[0025] (1) The multi-layer air-blow micro cable of the present application has a three-layer structure of a jacket in the optical unit, a first liquid crystal polymer layer, a first shear-resistant layer and a first protective layer, and the first liquid crystal polymer layer is formed by extrusion and stretching, so that fibers parallel to the optical fiber axis are formed inside the first liquid crystal polymer layer, which has excellent tensile resistance, impact toughness and dimensional stability, and can withstand a certain flattening force; the first shear-resistant layer has shear thickening properties, which will harden when impacted, avoiding direct transmission of external impact to the optical fiber element, and will not collapse like a foam material, absorbing energy after impact and returning to the original state, ensuring the overall configuration of the multi-layer air-blow micro cable, avoiding flattening of the optical cable after impact, affecting the anisotropy of the optical cable, and causing damage to the flattened part of the optical cable when it is stressed again; and the first protective layer can uniformly disperse external impact to the first shear-resistant layer, avoiding the problem of concentrated impact force breaking the cable, and greatly improving the impact resistance of the optical cable.

[0026] (2) The multi-layer air-blow micro cable of the present application has a three-layer structure of a jacket, a second liquid crystal layer, a second shear-resistant layer and a second protective layer, so that the jacket has similar impact resistance, impact force absorption and dispersion ability as the jacket, weakening external impact force and further avoiding transmission of external impact to the optical fiber element, thereby effectively protecting the internal optical fiber element.

[0027] (3) The multi-layer air-blow micro cable of the present application has a thickness ratio of the first liquid crystal polymer layer, the first shear-resistant layer and the first protective layer of 2:1:1, and the overall thickness of the jacket is not less than 0.38 mm. Because the first liquid crystal polymer layer itself has excellent impact resistance, the thickness of the first liquid crystal polymer layer is only 1 / 25 of the thickness of the high-density sponge under the premise of resisting the same impact force, so that the jacket and the jacket in the present application can effectively protect the internal optical fiber element while ensuring the characteristics of light weight and small outer diameter of the multi-layer air-blow micro cable, forming a jacket structure with a thickness of 0.38 mm in the present application, so that the multi-layer air-blow micro cable simultaneously has the characteristics of small structure size, light weight, good bending performance and strong tensile and impact resistance.

[0028] (4) The preparation method of the multi-layer air blown microcable of the present application strictly limits the extrusion temperature of the first liquid crystal polymer layer, the first shear-resistant layer and the first protective layer, adjusts the temperature range of the three, so that the three-layer structure can be formed in a molten state around the optical fiber element during melt extrusion, while avoiding the three-layer structure being too excellent in flowability, which causes the first liquid crystal polymer layer, the first shear-resistant layer and the first protective layer to fail to be formed into a three-layer structure, improving the forming quality of the multi-layer air blown microcable to provide good protection for the internal optical fiber element. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a cross-sectional structure schematic diagram of the multi-layer air blown microcable in the embodiment of the present application.

[0030] In all the drawings, the same reference signs represent the same technical features, specifically:

[0031] 1, optical fiber element; 2, first liquid crystal polymer layer; 3, first shear-resistant layer; 4, first protective layer; 5, central reinforcing member; 6, second liquid crystal polymer layer; 7, second shear-resistant layer; 8, second protective layer; 9, first water-blocking layer; 10, second water-blocking layer. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application clearer and more comprehensible, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0033] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0034] In addition, the terms "first", "second", etc. are used only for descriptive purposes and are not to be construed as indicating or implying relative importance or an ordered ranking of the indicated technical features. Thus, features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly and specifically limited.

[0035] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0037] Please refer to Figure 1 The multi-layer air-blow micro-cable in the preferred embodiment of the present application comprises a central reinforcing member 5, a plurality of optical units twistedly arranged outside the periphery of the central reinforcing member 5, each of the optical units comprising an optical fiber element 1 and a sleeve arranged outside the periphery of the optical fiber element 1, the sleeve comprising a first liquid crystal polymer layer 2, a first shear-resistant layer 3 and a first protective layer 4 arranged in sequence from inside to outside; and an outer sheath arranged outside the periphery of the plurality of optical units.

[0038] The present application sets the first liquid crystal polymer layer 2, the first shear-resistant layer 3 and the first protective layer 4 in sequence on the outer periphery of the optical fiber element 1. When the multi-layer air-blow micro-cable is subjected to external impact, the outermost first protective layer 4 will deform and disperse the impact force, the middle first shear-resistant layer 3 will shear and harden to absorb the impact dispersed by the first protective layer 4, and the innermost first liquid crystal polymer layer 2 will form a fiber structure uniformly arranged along the axial direction after being axially stretched to form a hard impact-resistant structure on the outer periphery of the optical fiber element 1, thereby avoiding the direct transmission of external impact to the optical fiber element 1. Through the setting of the three-layer structure, the external impact is dispersed and absorbed, and the transmission of the external impact to the optical fiber element 1 is avoided, thereby greatly improving the tensile, lateral pressure and impact resistance of the optical cable under the premise of ensuring the small structure size, light weight and good bending performance of the optical cable.

[0039] Preferably, the central reinforcing member 5 in the present application is preferably an FRP rod.

[0040] Further, as a preferred embodiment of the present application, the outer sheath in the present application comprises a second liquid crystal polymer layer 6, a second shear-resistant layer 7 and a second protective layer 8 arranged in sequence from inside to outside. The outer sheath as the outer structure of the multi-layer air-blow micro-cable can also be set as a three-layer structure similar to the sleeve in the present application. By setting the outer sheath as a three-layer structure, the part of the optical unit to which the external impact force is transmitted is smaller, further reducing the damage of the external impact to the optical unit and improving the impact resistance of the multi-layer air-blow micro-cable.

[0041] Further, as a preferred embodiment of the present application, the materials of the first liquid crystal polymer layer 2 and the second liquid crystal polymer layer 6 in the present application are one of LLCP (lyotropic liquid crystal polymer), TLCP (thermotropic liquid crystal polymer) and pressure-induced liquid crystal polymer. When a very thin layer of liquid crystal polymer is extruded on the outside of the optical fiber element 1 in an extrusion or semi-extrusion molding manner, the flow of the LCP (liquid crystal polymer) rod-shaped macromolecular chain will form an abnormally regular fiber structure through stretching, so that the mechanical strength and modulus level of the non-reinforced liquid crystal plastic can reach or even exceed that of the ordinary engineering plastic reinforced by several tens of percent of glass fiber. Preferably, the first liquid crystal polymer layer 2 and the second liquid crystal polymer layer 6 are doped with glass fiber or carbon fiber, which can significantly improve the tensile strength of LCP, and the glass fiber or carbon fiber accounts for less than 30% of the mass percentage of the first liquid crystal polymer layer 2 or the second liquid crystal polymer layer 6. Preferably, the first liquid crystal polymer layer 2 and the second liquid crystal polymer layer 6 herein are thermotropic liquid crystal polymers, which can be molded above the melting point or glass transition temperature and are suitable for the extrusion process of the optical cable.

[0042] Further, the first shear resistant layer 3 and the second shear resistant layer 7 both comprise shear thickening fluid. The shear thickening fluid can be selected as D3O (Dupont Hytrel reinforced D3O) or VPD (viscous polymer dispersion). The shear thickening fluid is a composite damping material synthesized by viscous glue and polymer, which is in a relaxed state, soft and elastic in normal state, and when subjected to a severe impact or extrusion, the molecules will immediately lock with each other, quickly tighten and harden to digest external force, forming a second protective layer 8. When the external force disappears, the material will return to the initial relaxed soft and elastic state. And under the same impact force, the thickness of the shear thickening fluid is 1 / 25 of the thickness of the high-density sponge. The shear thickening fluid can well absorb impact energy, and its thickness is relatively thin, so that the multi-layer air blown micro-cable has the characteristics of light weight and small diameter size.

[0043] Preferably, the outermost layer of the sleeve in the application adopts the first protective layer 4, which can be selected as TPE (thermoplastic elastomer), TPR (thermoplastic rubber) or TPEE (thermoplastic polyester elastomer), so that the first protective layer 4 has good resilience. When the light unit is impacted, the first protective layer 4 can uniformly disperse and transmit the external impact to the first shear resistant layer 3, reducing the damage of external impact to the optical fiber element 1.

[0044] Further, the outermost layer of the sleeve in the application adopts PP (polypropylene), and the forming temperature of PP is close to the forming temperature of D3O and TLCP, which is convenient for extrusion forming with the three-layer structure of the sleeve.

[0045] Further, the second protective layer 8 in the application is prepared from one of ethylene-propylene-diene rubber, chlorinated polyethylene rubber or chlorosulfonated polyethylene rubber. The use of rubber structure makes the bending performance of the optical cable better, and compared with the conventional PP (polypropylene) and PE structure of the outer sheath, it has better pressure resistance, avoiding the problem of cable damage and cracking in strong pressure environment such as deep sea.

[0046] Further, the second protective layer 8 in the application adopts PE (polyethylene), and compared with the rubber structure, the melt extrusion temperature of PE is similar to that of TLCP and D3O, so that the three can be co-extruded at the same time. At the same time, PE has good aging resistance, and its surface has a certain roughness, which is suitable for marking work after the preparation of the optical cable.

[0047] Further, in the multi-layer air-blow micro-cable of the present application, the overall wall thickness of the sleeve prepared by the first liquid crystal polymer layer 2, the first shear-resistant layer 3 and the first protective layer 4 is not less than 0.38 mm, and the thickness ratio of the three layers is 2:1:1. Further, in the preparation process, the thickness of each layer of the first liquid crystal polymer layer 2, the first shear-resistant layer 3 and the first protective layer 4 is not less than 0.1 mm. Here, the overall wall thickness is the wall thickness parameter obtained after stretching preparation adjustment. Here, the thickness of the first liquid crystal polymer layer 2 is thicker than that of the first shear-resistant layer 3 and the first protective layer 4, because the first liquid crystal polymer layer 2 will solidify along the extrusion flow direction after cooling, and it must have sufficient hardness when the impact comes to avoid the impact force being transmitted to the optical fiber element 1 as the impact matrix of the first shear-resistant layer 3 and the first protective layer 4.

[0048] Further, in the multi-layer air-blow micro-cable of the present application, the overall wall thickness of the outer sheath prepared by the second liquid crystal polymer layer 6, the second shear-resistant layer 7 and the second protective layer 8 is not less than 0.50 mm, and the thickness ratio of the three layers is 2:1:2. Here, the thickness of the second protective layer 8 needs to be adapted to increase so that the outer sheath has better wear resistance. It is worth noting that the overall wall thickness of the sleeve and the outer sheath here represents the basic parameters of the sleeve and the outer sheath in the optical cable preparation process to meet the optical fiber impact resistance, compression resistance and tensile resistance. It represents that the multi-layer air-blow micro-cable of the present application can prepare the optical cable to a smaller diameter and meet the thickness of the optical fiber attenuation standard. In the actual preparation process, the thickness of the sleeve and the outer sheath can be higher than the minimum wall thickness set in the present application, so that the optical cable has better compression resistance, impact resistance and tensile resistance.

[0049] Further preferably, in order to improve the water resistance of the multi-layer air-blow micro-cable of the present application, the first water resistance layer 9 is further provided on the outer periphery of the optical fiber element 1, and the second water resistance layer 10 is further provided between the optical unit and the outer sheath. The first water resistance layer 9 and the second water resistance layer 10 are both used to resist water, and can be selected from water resistance yarn, water resistance powder, water resistance paste, water resistance tape, etc. Of course, in order to avoid the weight of the multi-layer air-blow micro-cable of the present application being too large, the first water resistance layer 9 and the second water resistance layer 10 are preferably water resistance powder or water resistance yarn.

[0050] Optionally, other structures for facilitating the use of the optical cable, such as a cable opening rope, can be added to the outer sheath of the present application.

[0051] Further, as a preferred embodiment of the present application, the present application further includes a preparation method of a multi-layer air-blow micro-cable, which comprises the following steps:

[0052] S1, pulling the optical fiber element 1;

[0053] S2, synchronously extruding the first liquid crystal polymer layer 2, the first shear resistance layer 3 and the first protective layer 4 outside the periphery of the optical fiber element 1 to obtain an optical unit; wherein the extrusion temperature of the first liquid crystal polymer layer 2, the first shear resistance layer 3 and the first protective layer 4 is 220-230 DEG C; here the extrusion temperature is the temperature of the extrusion port at the head of the extruder, and 220-230 DEG C belongs to the normal range of the extrusion temperature.

[0054] S3, pulling the central reinforcing member 5 to be arranged, and twisting a plurality of optical units around the periphery of the central reinforcing member 5 as the center;

[0055] S4, synchronously extruding the second liquid crystal polymer layer 6, the second shear resistance layer 7 and the second protective layer 8 outside the periphery of the plurality of optical units to obtain a multi-layer air blown micro cable.

[0056] The preparation method of the multi-layer air blown micro cable in the application is mainly realized by using a co-extrusion process. Compared with the conventional step-by-step extrusion molding process, the co-extrusion process can avoid the problem of damage to the core layer caused by multi-layer step-by-step extrusion, which affects the overall tensile, compression and impact resistance of the optical cable. At the same time, the co-extrusion method makes the adhesion between the layers more compact. Under the condition that other process conditions are the same, the larger the friction coefficient between the layers, the better the compression resistance, and the water seepage problem between the layers can also be solved, the preparation process is reduced, and the preparation efficiency is improved.

[0057] Preferably, the first liquid crystal polymer layer 2 in step S2 of the application is TLCP, the first shear resistance layer 3 is D3O, and the first protective layer 4 is PP. Although solvate liquid crystal polymer, thermotropic liquid crystal polymer and piezotropic liquid crystal polymer can form a hard structure in a stretched state, based on the fact that the molding process of the optical cable itself is melt extrusion preparation, in order to realize the simultaneous melt extrusion of the first liquid crystal polymer layer 2, the first shear resistance layer 3 and the first protective layer 4, the first liquid crystal polymer layer 2 is selected as TLCP, so that the three can be synchronously melt extruded to protect the optical fiber element 1 inside.

[0058] Further, POE-g-GMA is added to the extrusion material of the first shear resistance layer 3 in step S2 of the application, and the POE-g-GMA accounts for 2-3wt% of the first shear layer. The solubility parameter of D3O is relatively small compared with that of PP and PE, the compatibility is good, and the melting point is also relatively small, which is convenient for synchronous melt co-extrusion molding. When the POE-g-GMA (polyolefin elastomer grafted glycidyl methacrylate) is added to the first shear resistance layer 3, the compatibility with PP and PE can be further improved, and the co-extrusion effect can be improved.

[0059] Furthermore, in step S2 of this application, ethylene glycol phenyl ether is added to the extruded material of the first liquid crystal polymer layer 2, and the ethylene glycol phenyl ether accounts for 1-5 wt% of the first liquid crystal polymer layer 2. TLCP itself does not have active groups, its surface is chemically inert, and its interfacial adhesion to the substrate is poor. In order to achieve the simultaneous extrusion of the first liquid crystal polymer layer 2, the first shear-resistant layer 3, and the first protective layer 4, ethylene glycol phenyl ether is added to the extruded material of the first liquid crystal polymer layer 2. This can increase the surface roughness of the TLCP, thereby improving its interfacial adhesion and facilitating the achievement of multilayer extrusion.

[0060] Furthermore, in step S2 of this application, a plasticizer is added to the extruded material of the first liquid crystal polymer layer 2, and the plasticizer accounts for 5-10 wt% of the first liquid crystal polymer layer 2. The preferred plasticizers here are soybean oil, chlorinated paraffin, DOP (dioctyl phthalate), and DBP (dibutyl phthalate). The melting point of TCLP is higher than that of D3O or PP / PE, typically at 270°C or above. However, when using melting temperatures suitable for D3O or PP / PE, TCLP cannot melt, preventing the co-extrusion of the three. When using melting temperatures suitable for TCLP, D3O and PP / PE will have excessively high extrusion temperatures, resulting in excessively good fluidity of the molten extruded material. This can easily lead to fluctuations in the diameter of the sleeve / outer sheath during extrusion molding, resulting in uneven optical cable dimensions, and even intermittent distribution of the outermost PP / PE layer, making it impossible to form the optical cable. Therefore, a plasticizer needs to be added here. By controlling the proportion of plasticizer added, the melting temperature of TLCP can be made close to that of D3O and PP / PE, thus achieving co-extrusion molding of the three. Preferably, the plasticizer content added to the first liquid crystal polymer layer 2 is 5-10 wt%, which can adjust the temperature of the first liquid crystal polymer layer 2 to around 220°C, so that it transforms into a molten state at 220-230°C.

[0061] Furthermore, the melting temperature ranges of the various layers of the aforementioned sleeve and outer sheath are the same or similar, and in the actual molding process, their extrusion temperatures can be the same or similar. Moreover, the additives or additive ratios mentioned above regarding improving the compatibility or melting temperature between the layers of the sleeve can be applied to the extrusion of each layer of the outer sheath.

[0062] Further, step S1 also includes setting a first water-blocking layer 9 on the outer periphery of the optical fiber element 1; step S3 also includes setting a second water-blocking layer 10 on the outer periphery of the stranded structure of the multiple optical units and the central reinforcing member 5. The setting of the first water-blocking layer 9 and the second water-blocking layer 10 can be adjusted according to the type of water-blocking yarn, water-blocking powder, water-blocking paste or water-blocking tape, etc., and the preparation process of the first water-blocking layer 9 and the second water-blocking layer 10 can be adjusted.

[0063] Example 1:

[0064] The following selection is an FRP with a diameter of 1.7mm for the central reinforcement 5, a sleeve diameter of 1.65mm, and a number of sleeves of 6. Each loose sleeve contains 6 optical fibers. The sleeves are twisted around the central reinforcement 5 using an SZ twisting method, and then an outer sheath is extruded around its outer periphery.

[0065] Specifically, the sleeve adopts TCLP-D3O-PP, with an overall wall thickness of 0.38mm, and the wall thickness ratio of TLCP / D3O / PP is 2:1:1. The temperature of the extruder head at the co-extrusion point of the three is 230℃.

[0066] The sheath is made of TCLP-D3O-PE with an overall wall thickness of 0.5mm. The wall thickness ratio of TCLP / D3O / PE is 2:1:2, and the temperature of the extruder head at the co-extrusion point is 230℃.

[0067] Comparative Example 1:

[0068] The sleeve adopts a PBT single-layer structure, the outer sheath adopts a PE single-layer structure, and other parameters are the same as in Example 1.

[0069] Comparative Example 2:

[0070] The casing adopts a single-layer PP structure, the sheath adopts a single-layer PE structure, and other parameters are the same as in Example 1.

[0071] Comparative Example 3:

[0072] The casing adopts a TPEE single-layer structure, and the sheath adopts a PE single-layer structure.

[0073] The above-described Example 1 and Comparative Examples 1, 2, and 3 were subjected to a flattening experiment with a flattening force of 800 N. The maximum attenuation change of the optical fiber during the flattening process was measured, as shown in the table below:

[0074]

[0075] Impact experiments were conducted on Example 1 and Comparative Examples 1, 2, and 3, and the maximum attenuation change of the optical fiber during the impact process was measured. The results are shown in the table below:

[0076]

[0077] Tensile tests were conducted on Example 1 and Comparative Examples 1, 2, and 3, and the maximum attenuation change of the optical fiber during a 1000N stretch was measured. The results are shown in the table below:

[0078]

[0079] Through the above comparison, it can be seen that when conventional sheath and outer sheath structures of the same thickness are used for flattening, impact and tensile tests, it is found that conventional optical cable structures, when made into sheaths and outer sheaths of the thickness of this application, suffer from severe signal attenuation, or even interruption.

[0080] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. 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 present invention.

Claims

1. A method for preparing a multilayer air-blown microcable, characterized in that, Includes the following steps: S1, traction fiber optic component; S2. A first liquid crystal polymer layer, a first shear-resistant layer, and a first protective layer are simultaneously extruded on the outer periphery of the optical fiber element to obtain an optical unit. The first liquid crystal polymer layer is TLCP, and ethylene glycol phenyl ether is added to the first liquid crystal polymer layer. The first shear-resistant layer is D3O, and POE-g-GMA is added to the first shear-resistant layer. The first protective layer is PP. The extrusion temperature of the first liquid crystal polymer layer, the first shear-resistant layer, and the first protective layer is 220~230℃. S3. A central reinforcing member is set for traction. Multiple optical units are traction-twisted around the outer periphery of the central reinforcing member with the reinforcing member as the center. S4. A second liquid crystal polymer layer, a second shear-resistant layer, and a second protective layer are simultaneously extruded on the outer periphery of multiple optical units to obtain a multilayer air-blown microcable.

2. The method for preparing multilayer air-blown microcables according to claim 1, characterized in that, In step S2, POE-g-GAM accounts for 2-3 wt% of the first shear-resistant layer.

3. The method for preparing multilayer air-blown microcables according to claim 1, characterized in that, The ethylene glycol phenyl ether mentioned in step S2 accounts for 1 to 5 wt% of the first liquid crystal polymer layer.

4. The method for preparing multilayer air-blown microcables according to claim 1, characterized in that, In step S2, a plasticizer is added to the extruded material of the first liquid crystal polymer layer, and the plasticizer accounts for 5 to 10 wt% of the first liquid crystal polymer layer.

5. The method for preparing multilayer air-blown microcables according to claim 1, characterized in that, Step S1 further includes setting a first water-blocking layer on the outer periphery of the optical fiber element; Step S3 further includes setting a second water-blocking layer on the outer periphery of the stranded structure of multiple optical units and the central reinforcing member.

6. A multi-layer air-blown microcable, characterized in that, include: Center reinforcement; Multiple optical units are stranded and disposed on the outer periphery of the central reinforcing member; Each of the aforementioned optical units includes an optical fiber element, and the optical fiber element is provided with a sleeve on its outer periphery; the sleeve includes a first liquid crystal polymer layer, a first shear-resistant layer and a first protective layer arranged sequentially from the inside to the outside; the first liquid crystal polymer layer is TLCP, and ethylene glycol phenyl ether is added to the first liquid crystal polymer layer; the first shear-resistant layer is D3O, and POE-g-GMA is added to the first shear-resistant layer; the first protective layer is PP; An outer sheath is disposed on the outer periphery of the plurality of optical units.

7. The multilayer air-blown microcable according to claim 6, characterized in that, The outer sheath includes a second liquid crystal polymer layer, a second shear-resistant layer, and a second protective layer arranged sequentially from the inside out.

8. The multilayer air-blown microcable according to claim 6 or 7, characterized in that, The thickness ratio of the first liquid crystal polymer layer, the first shear-resistant layer, and the first protective layer in the sleeve is 2:1:

1.

9. The multilayer air-blown microcable according to claim 7, characterized in that, The second liquid crystal polymer layer comprises one of a lyotropic liquid crystal polymer, a thermotropic liquid crystal polymer, and a compressive liquid crystal polymer; the second shear-resistant layer comprises a shear-thickening fluid.

Images