Green and environment-friendly air-blowing micro cable and preparation method thereof

Abstract

The invention discloses a green and environment-friendly air-blowing micro cable and a preparation method thereof, and belongs to the technical field of optical communication, the green and environment-friendly air-blowing micro cable comprises a central reinforcing member, and the central reinforcing member is made of a fiber-based material; the plurality of optical units are arranged on the periphery of the central reinforcing piece in a stranded manner; the optical unit comprises an optical fiber and a loose tube sleeving the periphery of the optical fiber, starch-based water-blocking paste is filled between the optical fiber and the loose tube, and the loose tube is prepared and formed by polylactic acid; and the outer sheath is prepared and formed by adopting bio-based polyurethane. All-component materials of the environment-friendly air-blowing micro-cable are replaced by partial bio-based materials, so that the use proportion of petroleum-based materials in the optical cable is reduced, and energy waste is reduced; besides, the fiber-based reinforcing member, the starch-based water-blocking paste, the loose tube made of polylactic acid and the outer sheath made of bio-based polyurethane do not cause too large damage to the environment, and the cable can be rapidly degraded under specific conditions and is relatively friendly to the environment.

Description

Technical Field

[0001] This invention belongs to the field of optical communication technology, specifically relating to a green and environmentally friendly air-blown microcable and its preparation method. Background Technology

[0002] Optical fiber cables are communication devices manufactured to meet optical, mechanical, or environmental performance specifications. They use one or more optical fibers encased in a sheath as a transmission medium to form a communication cable assembly, and are an essential component of modern communication transmission.

[0003] Driven by global carbon neutrality goals and environmental policies, the optical cable industry is facing the dual challenges of material upgrades and process innovation. Traditional optical cable manufacturing relies on petroleum-based materials (polyethylene, polyvinyl chloride, etc.), consuming large amounts of fossil fuels during the process. Furthermore, the cable's layer structure is primarily polyolefin, making it difficult to degrade after disposal. Landfilling or incinerating optical cables releases toxic gases and occupies land resources. Simultaneously, optical cables typically require duct or overhead installations, necessitating certain tensile, compressive, and bending strengths. Existing biodegradable materials generally cannot meet these performance and manufacturing requirements. Summary of the Invention

[0004] In response to one or more of the above-mentioned defects or improvement needs of existing technologies, the present invention provides a green and environmentally friendly air-blown microcable to solve the problem that the main components of existing optical cables are petroleum-based materials, resulting in a large waste of petrochemical resources.

[0005] To achieve the above objectives, the present invention provides a green and environmentally friendly air-blown microcable, comprising: A central reinforcement member, said central reinforcement member being made of a fiber-based material; Multiple optical units are stranded around the central reinforcing member; each optical unit includes an optical fiber and a loose tube sleeved around the optical fiber; starch-based water-blocking paste is filled between the optical fiber and the loose tube; the loose tube is made of polylactic acid. An outer sheath, which wraps around the periphery of the plurality of optical units, is made of bio-based polyurethane.

[0006] As a further improvement of the present invention, the central reinforcing member is made of a composite of bamboo fiber and basalt fiber.

[0007] As a further improvement of the present invention, the starch-based water-resistant paste comprises 40% starch, 20% glycerin, 30% montmorillonite and 10% water by weight.

[0008] As a further improvement of the present invention, the loose sleeve also contains nano bamboo charcoal filler.

[0009] As a further improvement of the present invention, a flame-retardant reinforcement layer is also provided on the outer periphery of the stranded structure formed by the plurality of optical units; The flame-retardant reinforcement layer has a double-layer structure, comprising a halogen-free flame-retardant hemp fiber strip layer wrapped around the outer periphery of the twisted structure formed by the plurality of optical units, and a basalt fiber mesh cloth wrapped around the outer periphery of the halogen-free flame-retardant hemp fiber strip layer.

[0010] As a further improvement of the present invention, a heat insulation layer is provided between the flame-retardant reinforcement layer and the outer sheath, the heat insulation layer covers the outer periphery of the flame-retardant reinforcement layer, and the heat insulation layer is made of aerogel felt.

[0011] This invention also includes a method for preparing a green and environmentally friendly air-blown microcable, which includes the following steps: Traction center reinforcement; The optical fiber is inserted into the loose tube, the loose tube is filled with starch-based water-blocking paste, and multiple loose tubes are twisted together around the outer periphery of the central reinforcing member. A flame-retardant reinforcement layer is formed by wrapping halogen-free flame-retardant hemp fiber strip and basalt fiber mesh cloth around the outer periphery of multiple loose-sleeve twisted structures. Aerogel felt is wrapped around the outer periphery of the flame-retardant reinforcement layer; A bio-based polyurethane outer sheath is extruded around the aerogel felt.

[0012] As a further improvement of the present invention, the central reinforcing member is prepared by means of the following steps: Bamboo fiber, basalt fiber and bio-based epoxy resin are selected. The bamboo fiber is 3-5 mm in length and 10-20 μm in diameter. The basalt fiber is 2 mm short chopped fiber. Then a silane coupling agent is added. Bamboo fiber is soaked in 5% sodium hydroxide solution for 2-2.5 hours, dried, and then mixed with basalt fiber, with silane coupling agent added. The mixed bamboo fiber and basalt fiber are fed into an epoxy resin adhesive bath; the temperature of the epoxy resin adhesive bath is 60℃, the solid content of the adhesive bath is 80%, and the amount of adhesive applied is 12%~15%. Bamboo fibers impregnated with epoxy resin and basalt fibers are fed into a pultrusion die, extruded, and cooled to obtain a central reinforcing member.

[0013] As a further improvement of the present invention, the loose sleeve is prepared in the following manner: Nano-bamboo charcoal is added to PLA resin, along with 0.2% of antioxidant by mass of the total granules. The molecular weight of the PLA resin is ≥150,000, the nano-bamboo charcoal particle size is 50nm, and the nano-bamboo charcoal accounts for 5~8% of the total granules by mass. PLA resin and nano bamboo charcoal were melt-blended and granulated in a twin-screw extruder to obtain loose-sleeve pipe granules; wherein the extrusion temperature of the twin-screw extruder was 180±3℃ and the screw speed was 150r / min. Loose sleeves are formed by extrusion using a single screw extruder.

[0014] As a further improvement of the present invention, the preparation of the bio-based polyurethane outer sheath includes: A prepolymer was obtained by reacting 70 parts by weight of castor oil-based polyol, 30 parts by weight of isophorone diisocyanate, and 0.1 parts by weight of catalyst at 80°C for 3 hours. Then, a chain extender (1,4-butanediol) was added and cured to obtain a bio-based polyurethane sheath material. The bio-based polyurethane sheath material was then added to an extruder and the bio-based outer sheath was obtained by vacuum sizing process.

[0015] The aforementioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0016] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include: (1) The green and environmentally friendly air-blown microcable of the present invention uses bio-based materials for the reinforcing members, loose tubes, water-blocking paste, and outer sheath of the optical cable, thereby replacing some of the materials in the optical cable with bio-based materials, reducing the proportion of petroleum-based materials used in the optical cable and reducing energy waste. In addition, the fiber-based reinforcing members, starch-based water-blocking paste, polylactic acid loose tubes, and bio-based polyurethane outer sheath will not cause much damage to the environment and can be rapidly degraded under certain conditions, making them environmentally friendly. The green and environmentally friendly air-blown microcable of the present invention replaces various structures in the optical cable with bio-based materials, reducing the use of petrochemical resources, reducing energy waste, and solving the problem that traditional optical cables are difficult to degrade after disposal, causing environmental pollution.

[0017] (2) The green and environmentally friendly air-blown microcable of the present invention has a central reinforcing member made of bamboo fiber and basalt fiber composite. The bamboo fiber provides flexibility, and the basalt fiber provides strength, so that the reinforcing member has tensile and bending resistance, which meets the requirements of the reinforcing member and realizes the replacement of traditional FRP or steel wire reinforcing members. At the same time, the starch-based water-blocking paste is made by mixing starch, glycerin, montmorillonite and water, which itself meets the water-blocking requirements of conventional water-blocking paste. The water-blocking paste is replaced by bio-based materials, realizing the replacement of water-blocking paste. In addition, this application uses halogen-free flame-retardant hemp fiber tape layer and basalt fiber mesh to form a flame-retardant structure, and the flame retardancy of the optical cable is realized by using fiber materials. The green and environmentally friendly air-blown microcable of the present invention replaces the reinforcing member, water-blocking material and flame-retardant material in the optical cable with bio-based materials, and achieves the corresponding functions through component and material adjustment, which meets the bending resistance, tensile strength, water-blocking and flame-retardant performance of the optical cable, meets the daily application standards of optical cable, and improves the applicability of optical cable. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the green and environmentally friendly air-blown microcable in an embodiment of the present invention; Figure 2 This is a schematic flowchart of the green and environmentally friendly air-blown microcable preparation method in this embodiment of the invention.

[0019] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1. Central reinforcement; 2. Optical fiber; 3. Loose tube; 4. Halogen-free flame-retardant hemp fiber tape layer; 5. Basalt fiber mesh; 6. Aerogel felt; 7. Outer sheath. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0021] In the description of this invention, it should be understood that, unless otherwise stated, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0022] Furthermore, unless otherwise stated, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0025] Example: Please see Figure 1 , Figure 2The green and environmentally friendly air-blown microcable in a preferred embodiment of the present invention includes: a central reinforcing member 1, which is made of fiber-based material; and multiple optical units, which are stranded around the periphery of the central reinforcing member 1; each optical unit includes an optical fiber 2 and a loose tube 3 sleeved around the periphery of the optical fiber 2, wherein starch-based water-blocking paste is filled between the optical fiber 2 and the loose tube 3, and the loose tube 3 is made of polylactic acid; and an outer sheath 7, which wraps around the periphery of the multiple optical units, and the outer sheath 7 is made of bio-based polyurethane.

[0026] Furthermore, as a preferred embodiment of the present invention, the central reinforcing member 1 is made of a composite of bamboo fiber and basalt fiber. Bamboo fiber has a certain degree of flexibility, which gives the central reinforcing member 1 certain bending performance and toughness, making it suitable for daily storage and wiring of optical cables; basalt fiber has good tensile strength and excellent temperature resistance; by combining bamboo fiber and basalt fiber, the central reinforcing member 1 meets the tensile and bending resistance requirements of optical cables, realizing the replacement of FRP or steel wire reinforcing members.

[0027] Preferably, the central reinforcing member 1 comprises 60 parts bamboo fiber, 30 parts basalt fiber, and 10 parts bio-based epoxy resin by weight. Since bamboo fiber and basalt fiber cannot be directly mixed and molded to obtain the central reinforcing member 1, bio-based epoxy resin is needed as a carrier to bond the bamboo fiber and basalt fiber together to form the structure of the central reinforcing member 1.

[0028] More preferably, the bamboo fiber and basalt fiber themselves have excellent physical and chemical properties, but they also have some drawbacks as reinforcing components.

[0029] Specifically, bamboo fiber contains hydroxyl groups, making it highly hygroscopic and prone to dimensional expansion. Furthermore, during the stripping process of optical cables or after damage, the bamboo fiber comes into contact with external moisture, causing the interface between the bamboo fiber and the epoxy resin to detach, resulting in the expansion and breakage of the central reinforcing member 1, rendering it ineffective. Therefore, when blending bamboo fiber with basalt fiber into bio-based epoxy resin, pretreatment of the bamboo fiber is necessary. Optionally, the bamboo fiber can be treated in a mixture of sodium chlorite and acetic acid to remove some of the lignin, and sodium periodate can be used to modify the bamboo fiber with aldehydes, increasing the aldehyde content on the bamboo fiber surface to form a hydrophobic layer and improve its waterproofing ability.

[0030] Furthermore, while basalt fiber itself possesses excellent properties, its surface energy is only 32 mN / m, resulting in poor interfacial adhesion between it and epoxy resin. This makes it difficult to mold a mixed structure of bamboo fiber, basalt fiber, and bio-based epoxy resin. Therefore, basalt fiber can be treated with a silane coupling agent and an ethanol solution containing a wetting and penetrating agent to modify its surface. This allows for a grafting rate of approximately 5%, improving the interfacial shear strength of the basalt fiber and enhancing its integration with the epoxy resin.

[0031] Alternatively, the tensile strength of bio-based epoxy resin is typically no greater than 45 MPa, and its mechanical properties are relatively weak. Even when reinforced with bamboo fiber and basalt fiber, breakage is likely to occur during the co-extrusion of bamboo fiber, basalt fiber, and bio-based epoxy resin. Therefore, graphene nanosheets can be added to the bio-based epoxy resin and ultrasonically dispersed to increase its tensile strength to over 60 MPa, ensuring the overall performance of the central reinforcing member 1.

[0032] Further, as a preferred embodiment of the present invention, the starch-based water-blocking paste of the present invention comprises, by weight, 40% starch, 20% glycerol, 30% montmorillonite, and 10% water. Starch is the main component of the starch-based water-blocking paste, and its good water absorption and swelling properties allow it to expand upon contact with water, sealing the damaged area of ​​the optical cable and preventing external moisture from continuing to penetrate the interior along the optical cable, thus achieving water blocking. Montmorillonite is a layered silicate mineral that can disperse into individual lamellar structures in water. When combined with starch for water blocking, the montmorillonite lamellars will be oriented within the expanded starch network, forming a layered barrier effect, thereby enhancing the water-blocking effect of starch and significantly reducing the penetration rate and distance of moisture when the optical cable is damaged. Glycerol is mainly used for plasticizing and adjusting the interfacial compatibility of starch, montmorillonite, etc. Glycerol can react with the hydroxyl groups of starch to form hydrogen bonds, reducing the molecular forces between starch molecules and making the molecular chains easier to slide. This allows the starch-based water-blocking paste to be sprayed as a fluid onto the outer periphery of the optical fiber 2, facilitating the formation of the optical unit. Water is used as a conventional dispersion medium and solvent to mix starch-based water-blocking paste into a whole, which will not be elaborated here.

[0033] Optionally, starch can rapidly swell after absorbing water and seal the damaged end of the optical cable. However, starch will hydrolyze when exposed to water for a long time, causing the water-blocking effect at the damaged area to fail. Therefore, the water absorption rate of starch can be reduced by adding a small amount of calcium chloride and citric acid through particle-co-linking technology.

[0034] Furthermore, as a preferred embodiment of the present invention, the loose sleeve 3 also contains nano-bamboo charcoal filler. The nano-bamboo charcoal filler is mainly used to increase the UV aging resistance of the loose sleeve 3, ensuring its long-term use. Optionally, the nano-bamboo charcoal filler accounts for 5% to 8% of the extruded material of the loose sleeve 3 by weight.

[0035] Further alternatively, while the loose tube 3 made of polylactic acid (PLA) does not have an environmental impact and its main components after degradation are water and carbon dioxide, making it an environmentally friendly material, PLA itself has a low glass transition temperature of only 55-60℃, and its mechanical properties decrease by 50% above 50℃, making it unsuitable for certain specific application environments and locations of optical cables. Based on this, the loose tube 3 in this application is a PLA / polycarbonate blend modified tube, with a trace amount of nucleating agent added to both PLA and polycarbonate, increasing the heat distortion temperature of the loose tube 3 to approximately 110℃, making it suitable for conventional optical cable usage environments. The mass ratio of PLA to polycarbonate is 7:3, thus obtaining a loose tube 3 structure with a heat distortion temperature of approximately 110℃. Optionally, the nucleating agent accounts for 0.2% of the total mass of the loose tube 3, and the preferred nucleating agent is TMC-328.

[0036] Furthermore, as a preferred embodiment of the present invention, the outer periphery of the stranded structure formed by the multiple optical units is further provided with a flame-retardant reinforcement layer; the flame-retardant reinforcement layer is a double-layer structure, comprising a halogen-free flame-retardant hemp fiber tape layer 4 wrapped around the outer periphery of the stranded structure formed by the multiple optical units, and a basalt fiber mesh fabric 5 wrapped around the outer periphery of the halogen-free flame-retardant hemp fiber tape layer 4. The halogen-free flame-retardant hemp fiber tape has fire-retardant properties, and the basalt mesh fabric can form a physically flame-retardant structure and has good resistance to lateral pressure; the combination of the two forms a fire-resistant and pressure-resistant structural layer.

[0037] Furthermore, the halogen-free flame-retardant hemp fiber tape layer 4 in this application has similar problems to bamboo fiber. The moisture absorption rate of the halogen-free flame-retardant hemp fiber tape layer 4 is as high as 12%, and the basalt fiber mesh fabric 5 cannot effectively isolate moisture, causing the halogen-free flame-retardant hemp fiber tape layer 4 to easily absorb water, resulting in a decrease in fire resistance. After absorbing water, the limiting oxygen index (LOI) of the halogen-free flame-retardant hemp fiber tape layer 4 drops from around 32% to below 25%, significantly affecting the fire resistance of the optical cable. Therefore, before stranding and coating, the halogen-free flame-retardant hemp fiber tape layer 4 in this invention uses a methyltrimethoxysilane sol-gel method to form a silica coating on its surface, thereby reducing the moisture absorption rate and improving its flame-retardant ability.

[0038] Furthermore, the flame-retardant reinforcement layer in this application is composed of a halogen-free flame-retardant hemp fiber tape layer 4 and a basalt fiber mesh fabric 5 stacked together. The air-blown microcable itself is relatively small, and the interfacial bonding force between the basalt fiber mesh fabric 5 and the halogen-free flame-retardant hemp fiber tape layer 4 is weak. To reduce the overall thickness of the flame-retardant reinforcement layer and improve its integrity, a bio-based polyurethane adhesive can be coated on the side of the basalt fiber mesh fabric 5 facing the halogen-free flame-retardant hemp fiber tape layer 4, with a small amount of nano-titanium dioxide added, thereby bonding the halogen-free flame-retardant hemp fiber tape layer 4 and the basalt fiber mesh fabric 5 together. It is worth noting that the basalt fiber mesh fabric 5 itself has a porous fiber structure; coating its surface with a bio-based polyurethane adhesive does not significantly increase the overall thickness of the flame-retardant reinforcement layer and does not affect the miniaturization of the air-blown microcable.

[0039] Furthermore, as an optional embodiment of the present invention, an aerogel felt 6 is also provided on the side of the basalt fiber mesh 5 facing the outer sheath 7. The aerogel felt 6 is mainly composed of silica aerogel with a nanoscale porous structure and is attached with glass fiber, ceramic fiber, or basalt fiber. It also contains a small amount of binder to bond the fibers and silica aerogel together. The thermal conductivity of the aerogel felt 6 is 0.015 W / (m·K), which provides good thermal insulation, reduces heat transfer from the external environment to the inside of the optical cable, further reduces the combustion efficiency of the flame-retardant reinforcement layer, and improves the fire resistance of the optical cable. On the other hand, the excellent thermal insulation performance of the aerogel felt 6 can also prevent the influence of the external ambient temperature on the inside of the optical cable, reduce the shrinkage rate of the starch-based water-blocking paste and loose tube 3, and reduce the attenuation loss of the optical fiber 2.

[0040] Furthermore, as an optional embodiment of the present invention, the outer sheath 7 in the present invention is a bio-based polyurethane outer sheath 7. Although bio-based polyurethane is an environmentally friendly material, its weather resistance is insufficient. Bio-based polyurethane exhibits poor weather resistance under ultraviolet light (340nm, irradiance 0.55W / m²). 2 After 1000 hours of irradiation, the tensile strength decreases by approximately 40%, making it unsuitable for long-term use. Therefore, this invention adds trifluoroacetyl chloride during the synthesis of bio-based polyurethane to increase the fluorine content of the optical cable sheath, thereby increasing the tensile strength of the outer sheath after aging and making the optical cable suitable for long-term use.

[0041] Alternatively, basalt short fibers may be added to the bio-based polyurethane sheath material to increase the tensile strength of the outer sheath 7.

[0042] Furthermore, regarding the green and environmentally friendly air-blown microcable of the present invention, a method for preparing the green and environmentally friendly air-blown microcable is also included, which comprises the following steps: Traction center reinforcement 1; Insert the optical fiber 2 into the loose tube 3, fill the loose tube 3 with starch-based water-blocking paste, and twist multiple loose tubes 3 around the outer periphery of the central reinforcing member 1. A flame-retardant reinforcement layer is formed by wrapping a halogen-free flame-retardant hemp fiber strip layer 4 and a basalt fiber mesh cloth 5 around the outer periphery of multiple loose tubes 3 twisted structures. Aerogel felt 6 is wrapped around the outer periphery of the flame-retardant reinforcement layer; A bio-based polyurethane outer sheath 7 is extruded around the aerogel felt 6.

[0043] Optionally, the center reinforcement 1 is pulled by a traction device and the center shaft of the stranding machine, and the traction tension of the center reinforcement 1 is controlled at 50~80N; Optionally, the loose tube 3 contains two optical fibers 2; six loose tubes 3 are twisted around the outer periphery of the central reinforcing member 1, with a twisting pitch of 150~200mm and a twisting angle of 18°~22°.

[0044] Optionally, the halogen-free flame-retardant hemp fiber tape layer 4 is wound with a spiral angle of 50±5°, an overlap rate of 20%, and a tension controlled at 10~15N; the basalt fiber mesh fabric 5 is wound in the opposite direction to the halogen-free flame-retardant hemp fiber tape layer 4, with a winding angle of 45°±5° and an overlap rate of 15%.

[0045] Furthermore, as an optional embodiment of the present invention, the preparation of the central reinforcement 1 includes the following steps: Bamboo fiber, basalt fiber, and bio-based epoxy resin are selected. The length of the bamboo fiber is 3-5 mm and the diameter is 10-20 μm. The basalt fiber is a 2 mm short chopped fiber. A silane coupling agent is added. The silane coupling agent accounts for 0.5% of the total mass fraction of the central reinforcing member 1.

[0046] Bamboo fiber is soaked in 5% sodium hydroxide solution for 2-2.5 hours, dried, and then mixed with basalt fiber, with silane coupling agent added. The mixed bamboo fiber and basalt fiber are fed into an epoxy resin adhesive tank; the temperature of the epoxy resin adhesive tank is 60℃, the solid content of the adhesive tank is 80%, and the amount of adhesive applied is 12%~15%.

[0047] Bamboo fiber and basalt fiber impregnated with epoxy resin were fed into a pultrusion die, extruded, and cooled to obtain the central reinforcement 1. The temperature of the pultrusion die was 120℃, the pressure of the pultrusion die was 1.5~2.0MPa, the traction rate of the bamboo fiber and basalt fiber hybrid structure was 2m / min, and the diameter of the pultruded central reinforcement 1 was 2.0±0.1mm.

[0048] Specifically, in the central reinforcing member 1 of the present invention, the total integral of bamboo fiber and basalt fiber accounts for more than 65% of the central reinforcing member 1, and the overall tensile strength of the central reinforcing member 1 is ≥1200MPa.

[0049] Furthermore, as an optional embodiment of the present invention, the preparation of the loose sleeve 3 includes the following steps: Nano-bamboo charcoal and 0.2% (by mass) of antioxidant were added to PLA resin to increase the thermal degradation temperature of loose-sleeve pipe 3. Specifically, the PLA resin had a molecular weight ≥150,000, the nano-bamboo charcoal had a particle size of 50 nm, and the nano-bamboo charcoal accounted for 5-8% of the total mass of the granules. PLA resin and nano bamboo charcoal were melt-blended and granulated in a twin-screw extruder to obtain loose-sleeve pipe granules; wherein the extrusion temperature of the twin-screw extruder was 180±3℃ and the screw speed was 150r / min. Loose-sleeve tube 3 is formed by extrusion using a single-screw extruder. The temperature of the feeding section of the single-screw extruder is 170℃, the temperature of the melting section is 185℃, and the temperature of the die extrusion head is 175℃.

[0050] Specifically, the PLA loose tube 3 of the present invention retains more than 90% of its tensile strength after 1000 hours of ultraviolet irradiation, and has a water permeability of ≤0.1g / 24h.

[0051] Further, as an optional embodiment of the present invention, the bio-based polyurethane outer sheath 7 of the present invention is prepared by reacting 70 parts by weight of castor oil-based polyol, 30 parts by weight of isophorone diisocyanate, and adding 0.1 parts by weight of catalyst at 80°C for 3 hours to obtain a prepolymer, and then adding a chain extender (1,4-butanediol) to cure and mold to obtain a bio-based polyurethane sheath material; then the bio-based polyurethane sheath material is added to an extruder, and then the bio-based outer sheath 7 is obtained by vacuum sizing process.

[0052] In the extrusion process of bio-based polyurethane sheath material, the temperature of the extruder's feeding section is 160℃, the temperature of the melting section is 180℃, the temperature of the die head is 170℃, and the vacuum degree of the vacuum sizing sleeve is 0.05MPa.

[0053] Furthermore, the green and environmentally friendly air-blown microcable of this invention has a tensile strength ≥1500N (YD / T 769-2018), a lateral compressive strength ≥3000N / 100mm (GB / T 2951.41-2008), good impact resistance, and no breakage in a 1m drop hammer test (IEC 60794-1-2).

[0054] Furthermore, regarding the environmentally friendly air-blown microcable of this invention, composting tests were conducted according to GB / T 19277.1. After 180 days, the degradation rate of the central reinforcing member 1 was ≥85%, the PLA loose tube 3 was ≥80%, and the bio-based polyurethane outer sheath 7 was ≥55%. The environmentally friendly air-blown microcable, calculated according to ISO 14067, has a carbon emission of ≤1.2kg CO2 / m over its entire life cycle, which is approximately 58% lower than that of traditional optical cables. The combustion smoke of the environmentally friendly air-blown microcable passed the EN 50268-2 test, with halogen acid gas release <5mg / m. 3 It meets the requirements for halogen-free environmental protection.

[0055] 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 green and environmentally friendly air-blown microcable, characterized in that, include: A central reinforcement member, said central reinforcement member being made of a fiber-based material; Multiple optical units are twisted together on the outer periphery of the central reinforcing member; Each of the optical units includes an optical fiber and a loose tube sleeved around the outer periphery of the optical fiber. The space between the optical fiber and the loose tube is filled with starch-based water-blocking paste. The loose tube is made of polylactic acid. An outer sheath, which wraps around the periphery of the plurality of optical units, is made of bio-based polyurethane.

2. The green and environmentally friendly air-blown microcable according to claim 1, characterized in that, The central reinforcing component is made of a composite of bamboo fiber and basalt fiber.

3. The green and environmentally friendly air-blown microcable according to claim 1, characterized in that, The starch-based water-resistant paste comprises, by weight, 40% starch, 20% glycerin, 30% montmorillonite, and 10% water.

4. The green and environmentally friendly air-blown microcable according to claim 1, characterized in that, The loose sleeve also contains nano bamboo charcoal filler.

5. The green and environmentally friendly air-blown microcable according to claim 1, characterized in that, A flame-retardant reinforcement layer is also provided on the outer periphery of the stranded structure formed by the multiple optical units; The flame-retardant reinforcement layer has a double-layer structure, comprising a halogen-free flame-retardant hemp fiber strip layer wrapped around the outer periphery of the twisted structure formed by the plurality of optical units, and a basalt fiber mesh cloth wrapped around the outer periphery of the halogen-free flame-retardant hemp fiber strip layer.

6. The green and environmentally friendly air-blown microcable according to claim 5, characterized in that, A thermal insulation layer is also provided between the flame-retardant reinforcement layer and the outer sheath. The thermal insulation layer covers the outer periphery of the flame-retardant reinforcement layer and is made of aerogel felt.

7. A method for preparing a green and environmentally friendly air-blown microcable, characterized in that, Includes the following steps: Traction center reinforcement; The optical fiber is inserted into the loose tube, the loose tube is filled with starch-based water-blocking paste, and multiple loose tubes are twisted together around the outer periphery of the central reinforcing member. A flame-retardant reinforcement layer is formed by wrapping halogen-free flame-retardant hemp fiber strip and basalt fiber mesh cloth around the outer periphery of multiple loose-sleeve twisted structures. Aerogel felt is wrapped around the outer periphery of the flame-retardant reinforcement layer; A bio-based polyurethane outer sheath is extruded around the aerogel felt.

8. The method for preparing the green and environmentally friendly air-blown microcable according to claim 7, characterized in that, The central reinforcing member is prepared by means of the following steps: Bamboo fiber, basalt fiber and bio-based epoxy resin are selected. The bamboo fiber is 3-5 mm in length and 10-20 μm in diameter. The basalt fiber is 2 mm short chopped fiber. Then a silane coupling agent is added. Bamboo fiber is soaked in 5% sodium hydroxide solution for 2-2.5 hours, dried, and then mixed with basalt fiber, with silane coupling agent added. The mixed bamboo fiber and basalt fiber are fed into an epoxy resin adhesive bath; the temperature of the epoxy resin adhesive bath is 60℃, the solid content of the adhesive bath is 80%, and the amount of adhesive applied is 12%~15%. Bamboo fibers impregnated with epoxy resin and basalt fibers are fed into a pultrusion die, extruded, and cooled to obtain a central reinforcing member.

9. The method for preparing the green and environmentally friendly air-blown microcable according to claim 7, characterized in that, The loose sleeve is prepared in the following manner: Nano-bamboo charcoal is added to PLA resin, along with 0.2% of antioxidant by mass of the total granules. The molecular weight of the PLA resin is ≥150,000, the nano-bamboo charcoal particle size is 50nm, and the nano-bamboo charcoal accounts for 5~8% of the total granules by mass. PLA resin and nano bamboo charcoal were melt-blended and granulated in a twin-screw extruder to obtain loose-sleeve pipe granules; wherein the extrusion temperature of the twin-screw extruder was 180±3℃ and the screw speed was 150r / min. Loose sleeves are formed by extrusion using a single screw extruder.

10. The method for preparing the green and environmentally friendly air-blown microcable according to claim 7, characterized in that, The preparation of the bio-based polyurethane outer sheath includes: A prepolymer was obtained by reacting 70 parts by weight of castor oil-based polyol, 30 parts by weight of isophorone diisocyanate, and 0.1 parts by weight of catalyst at 80°C for 3 hours. Then, a chain extender (1,4-butanediol) was added and cured to obtain a bio-based polyurethane sheath material. The bio-based polyurethane sheath material was then added to an extruder and the bio-based outer sheath was obtained by vacuum sizing process.

Images