Ointment-free dry-type flame-retardant fire-resistant optical cable and preparation method thereof

Abstract

The invention relates to the technical field of optical cables, in particular to a factice-free dry-type flame-retardant fire-resistant optical cable and a preparation method thereof.The factice-free dry-type flame-retardant fire-resistant optical cable comprises a plurality of independent fire-resistant optical fiber units, each fire-resistant optical fiber unit comprises an optical fiber unit arranged in a loose tube, and the space between each optical fiber unit and the loose tube is filled with an aerogel water-blocking material; ceramic flame-retardant polyolefin is coated outside the loose tube; a plurality of independent fire-resistant optical fiber units are twisted around the central reinforcing piece to form a cable core, and gaps of the cable core are sealed by silicone gel; the cable core is wrapped by an aluminum foil-ceramic silicone rubber composite tape, and the aluminum foil-ceramic silicone rubber composite tape is wrapped by a braid layer. And a sheath is sleeved outside the braid layer. The loose tube is filled with the nanoscale aerogel water-blocking material, traditional ointment is replaced, the light transmittance is improved, no smoke is released during combustion, cleaning ointment is not needed during construction, wiping is avoided, direct connection is achieved, and the working time is shortened; and a single-sheath structure is adopted, so that the outer diameter and the weight are reduced compared with those of a traditional double-sheath structure, and the cable has better flame-retardant and fire-resistant performance.

Description

Technical Field

[0001] The present invention relates to the technical field of optical cables, and particularly to an oil-free dry-type flame-retardant and fire-resistant optical cable and a preparation method thereof. Background Art

[0002] At present, the railway tunnels mainly adopt loose tube optical cables filled with grease (such as GYTA type), which have the following problems: 1) Grease dependence problem: In a low-temperature environment (such as in winter in the north), the grease is prone to solidify, resulting in an increase in the micro-bending loss of the optical fiber; After high temperature or long-term use, the grease is prone to leakage, polluting the environment and having a high maintenance cost; The grease filling leads to enhanced after-flame combustion and releases toxic thick smoke; 2) The double-sheath structure has a large outer diameter and high weight, making construction and transportation difficult; 3) The fire-resistant performance only meets the requirements during the combustion stage, and the optical fiber is prone to break during the cooling stage. Summary of the Invention

[0003] The present invention solves the problems in the related art and provides an oil-free dry-type flame-retardant and fire-resistant optical cable and a preparation method thereof. A nano-aerogel water-blocking material is filled in the loose tube to replace the traditional grease, improving the light transmittance, releasing no smoke during combustion, eliminating the need for cleaning grease during construction, allowing for direct splicing without wiping, and shortening the working hours; a single-sheath structure is adopted, reducing the outer diameter and weight compared with the traditional double-sheath structure, and having good flame-retardant and fire-resistant properties.

[0004] To solve the above technical problems, the present invention is realized through the following technical solutions: An oil-free dry-type flame-retardant and fire-resistant optical cable includes: A plurality of independent fire-resistant optical fiber units, each of the fire-resistant optical fiber units including an optical fiber unit disposed in a loose tube, a nano-aerogel water-blocking material filled between the optical fiber unit and the loose tube, and a ceramifiable flame-retardant polyolefin coated outside the loose tube; A central strength member, a plurality of independent fire-resistant optical fiber units being stranded around the central strength member to form a cable core, and the gap of the cable core being sealed with silicone gel; An aluminum foil-ceramifiable silicone rubber composite tape, wrapped outside the cable core; A braided layer, wrapped around the aluminum foil-ceramifiable silicone rubber composite tape; A sheath, sleeved outside the braided layer.

[0005] As a preferred solution, the loose tube is made of PP or PBT.

[0006] As a preferred solution, the central strength member is made of high-strength aramid fiber or glass fiber.

[0007] As a preferred solution, the braided layer is a braided layer made of basalt fiber / aramid mixed braiding.

[0008] As a preferred solution, the sheath is made of low-smoke, halogen-free and flame-retardant polyolefin.

[0009] On the other hand, the present invention also provides a preparation method of an oil-free dry-type flame-retardant and fire-resistant optical cable, and the steps are as follows: S1. Prepare an optical fiber unit: Introduce multiple single-mode or multi-mode optical fibers into an extruder, and through the extruder, extrude and fill a nano-level aerogel water-blocking material into a loose tube to form a water-tight layer; S2. Prepare an independent fire-resistant optical unit: Introduce the optical fiber loose tube into an extruder, and through the extruder, directly coat the loose tube with a ceramifiable flame-retardant polyolefin to form an independent fire-resistant optical unit; S3. Prepare a cable core: Spirally twist multiple independent fire-resistant optical units around the outer circumference of a central strengthening member at equal pitches with the central strengthening member as the axis. While spirally twisting, extrude and fill silicone gel into the gaps between the independent fire-resistant optical units and the central strengthening member and the outer circumference of the independent fire-resistant optical units to form a water-tight layer, and longitudinally wrap an aluminum foil-ceramifiable silicone rubber composite tape outside the cable core formed with the water-tight layer, so as to form a longitudinal fire-blocking barrier outside the cable core; S4. Wind a braided layer made of basalt fiber / aramid mixed braiding outside the cable core to form a tensile strengthening member, and prepare a sheath outside the braided layer by extrusion coating with low-smoke, halogen-free and flame-retardant polyolefin.

[0010] Compared with the prior art, the beneficial effects of the present invention are: (1) Cancel the traditional outer fire-resistant coating, and directly coat the optical fiber loose tube with a ceramifiable flame-retardant polyolefin to form an independent fire-resistant optical unit; adopt a single-sheath structure, the outer diameter is reduced by 25% compared with the traditional double sheath, and the weight is reduced by 10%; (2) Fill a nano-level aerogel water-blocking material in the loose tube to replace the traditional ointment, the light transmittance is increased by 40%, no smoke is released during combustion, and the cable core gap is sealed with silicone gel to achieve IP68-level waterproof performance; (3) The outer sheath is a braided layer made of basalt fiber / aramid mixed braiding, with a temperature resistance of up to 1000 °C, and an aluminum foil-ceramifiable silicone rubber composite tape is arranged between the core layer and the outer sheath to form a longitudinal fire-blocking barrier; (4) There is no cleaning ointment during construction, and it can be directly connected without wiping, and the working hours are shortened by 40%. Description of the Drawings

[0011] Figure 1 is a schematic diagram of the overall structure of the oil-free dry-type flame-retardant and fire-resistant optical cable of the present invention.

[0012] In the figure: 1. Optical fiber, 2. Aerogel water-blocking material, 3. Loose tube, 4. Ceramifiable flame-retardant polyolefin, 5. Central strength member, 6. Silicone gel, 7. Aluminum foil-ceramifiable silicone rubber composite tape, 8. Braided layer, 9. Sheath. Detailed implementation manners

[0013] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The description of at least one exemplary embodiment below is actually only illustrative and in no way limits the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0014] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0015] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be regarded as part of the authorized specification. In all the examples shown and discussed herein, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0016] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by orientation terms such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom", etc. is usually based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description. Without contrary explanation, these orientation terms do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the protection scope of the present invention; the orientation terms "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0017] For the convenience of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above" etc. can be used here to describe the spatial positional relationship of a device or feature shown in the figure with other devices or features. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation described in the figure for the device. For example, if the device in the drawing is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned as "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above..." can include both the orientations of "above..." and "below...". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations should be made for the spatial relative descriptions used here.

[0018] In addition, it should be noted that using words such as "first", "second" etc. to limit components is only for the convenience of differentiating the corresponding components. Without separate statement, the above words have no special meaning. Therefore, it should not be construed as a limitation on the protection scope of the present invention.

[0019] Embodiment 1 As Figure 1As shown in the figure, an oil-free dry-type flame-retardant and fire-resistant optical cable includes a number of independent fire-resistant optical fiber units, a central strengthening member 5, an aluminum foil-ceramicized silicone rubber composite tape 7, a braided layer 8, and a sheath 9. The fire-resistant optical fiber unit includes an optical fiber unit disposed in a loose tube 3. The optical fiber unit is composed of multiple single-mode or multi-mode optical fibers 1. An aerogel water-blocking material 2 is filled between the optical fiber unit and the loose tube 3. The aerogel water-blocking material 2 can adopt a nano-level aerogel water-blocking material 2, replacing the traditional ointment, with a 40% increase in light transmittance and no smoke release during combustion; the loose tube 3 is coated with a ceramicized flame-retardant polyolefin 4; a number of independent fire-resistant optical fiber units are stranded around the central strengthening member 5 to form a cable core, and the gap of the cable core is sealed with silicone gel 6 to achieve IP68-level waterproof performance; the aluminum foil-ceramicized silicone rubber composite tape 7 is wrapped outside the cable core to form a longitudinal fire-blocking barrier; the braided layer 8 is wound around the aluminum foil-ceramicized silicone rubber composite tape 7; the sheath 9 is sleeved outside the braided layer 8.

[0020] In one embodiment, the loose tube 3 is made of PP or PBT.

[0021] In one embodiment, the central strengthening member 5 is made of high-strength aramid fiber or glass fiber.

[0022] In one embodiment, the braided layer 8 is a braided layer made of a mixture of basalt fiber and aramid, and the temperature resistance can reach 1000°C.

[0023] In one embodiment, the sheath 9 is made of a low-smoke and halogen-free flame-retardant polyolefin.

[0024] Embodiment 2 On the other hand, the present invention also provides a preparation method for an oil-free dry-type flame-retardant and fire-resistant optical cable, and the steps are as follows: S1. Prepare the optical fiber unit: Introduce multiple single-mode or multi-mode optical fibers 1 into an extruder, and through the extruder, extrude and fill the nano-level aerogel water-blocking material 2 into the loose tube 3 to form a water-tight layer; S2. Prepare independent fire-resistant optical units: Introduce the optical fiber loose tube into an extruder, and through the extruder, directly coat the ceramicized flame-retardant polyolefin 4 outside the loose tube 3 to form independent fire-resistant optical units; S3. Prepare the cable core: Stranded multiple independent fire-resistant optical units around the central strengthening member 5 in an equal pitch spiral around the outer circumference of the central strengthening member 5. While spirally stranding, extrude and fill the silicone gel 6 into the gap between the independent fire-resistant optical units and the central strengthening member 5 and the outer circumference of the independent fire-resistant optical units to form a water-tight layer, and longitudinally wrap the aluminum foil-ceramicized silicone rubber composite tape 7 outside the cable core with the water-tight layer formed, so as to form a longitudinal fire-blocking barrier outside the cable core; S4. Wrap a braided layer 8 made of a mixture of basalt fiber and aramid outside the cable core to form a tensile reinforcement member, and prepare the sheath 9 by extruding and coating a low-smoke and halogen-free flame-retardant polyolefin outside the braided layer 8.

[0025] The optical cable prepared by the present invention is applicable to the railway tunnel environment, especially for the requirements of flame retardancy, fire resistance, environmental protection and long-term reliability of optical cables in closed tunnel scenarios such as high-speed railways and subways. Through the design of an oil-free dry water-blocking structure, a multi-layer composite flame retardant material system and an optimized preparation process, the signal transmission integrity, low-smoke and halogen-free environmental protection characteristics and maintenance-free long-term operation of the optical cable under extreme fire conditions are realized.

[0026] The above are the preferred embodiments of the present invention. Those skilled in the art to which the present invention pertains can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the above specific embodiments, and any obvious improvements, substitutions or variations made by those skilled in the art on the basis of the present invention all fall within the protection scope of the present invention.

Claims

1. An oil-free dry-type flame-retardant and fire-resistant optical cable, characterized in that, Comprising: A plurality of independent fire-resistant optical fiber units, each of the fire-resistant optical fiber units comprising an optical fiber unit disposed in a loose tube, an aerogel water-blocking material being filled between the optical fiber unit and the loose tube, and the loose tube being coated with a ceramifiable flame-retardant polyolefin; A central strength member, a plurality of independent fire-resistant optical fiber units being stranded around the central strength member to form a cable core, and the gaps of the cable core being sealed with silicone gel; An aluminum foil-ceramifiable silicone rubber composite tape, wrapped around the cable core; A braided layer, wound around the aluminum foil-ceramifiable silicone rubber composite tape; A sheath, sleeved outside the braided layer.

2. The oil-free dry-type flame-retardant and fire-resistant optical cable according to claim 1, characterized in that: The loose tube is made of PP or PBT.

3. The oil-free dry-type flame-retardant and fire-resistant optical cable according to claim 1, characterized in that: The central strength member is made of high-strength aramid fiber or glass fiber.

4. The oil-free dry-type flame-retardant and fire-resistant optical cable according to claim 1, characterized in that: The braided layer is a braided layer of basalt fiber / aramid mixed braiding.

5. The oil-free dry-type flame-retardant and fire-resistant optical cable according to claim 1, wherein: The sheath is made of a low-smoke and halogen-free flame-retardant polyolefin.

6. A preparation method of an oil-free dry-type flame-retardant and fire-resistant optical cable, characterized in that, The steps are as follows: S1. Prepare an optical fiber loose tube: Introduce a plurality of single-mode or multi-mode optical fibers into an extruder, and extrude and fill a nano-level aerogel water-blocking material into the loose tube through the extruder to form a water-tight layer; S2. Prepare an independent fire-resistant optical unit: Introduce the optical fiber loose tube into an extruder, and directly coat the loose tube with a ceramifiable flame-retardant polyolefin through the extruder to form an independent fire-resistant optical unit; S3. Prepare a cable core: Strand a plurality of independent fire-resistant optical units around the central strength member in an equal pitch spiral outside the central strength member, and while spirally stranding, extrude and fill silicone gel into the gaps between the independent fire-resistant optical units and the central strength member and the outside of the independent fire-resistant optical units to form a water-tight layer, and longitudinally wrap an aluminum foil-ceramifiable silicone rubber composite tape outside the cable core forming the water-tight layer, thereby forming a longitudinal fire barrier outside the cable core; S4. Wrap a braided layer of basalt fiber / aramid mixed braiding outside the cable core to form a tensile reinforcement member, and prepare a sheath outside the braided layer by extrusion coating with a low-smoke and halogen-free flame-retardant polyolefin.

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