B1-level flame-retardant non-dripping high-performance transmission leaky coaxial cable and manufacturing method thereof

Abstract

The invention belongs to the technical field of leaky coaxial cables, and particularly relates to a B1-level flame-retardant non-dripping high-performance transmission leaky coaxial cable and a manufacturing method thereof. The B1-level flame-retardant non-dripping high-performance transmission leaky coaxial cable sequentially comprises an inner conductor, an insulating layer, an outer conductor, a belting layer and an outer sheath from the inner layer to the outer layer. The outer sheath is prepared from the following raw materials: 10-20 parts of an ethylene-vinyl acetate copolymer (EVA); 10 to 20 parts of POE (polyolefin elastomer); 5 to 10 parts of maleic anhydride grafted polyethylene; 50 to 70 parts of metal hydroxide; 0.5-2 parts of a processing aid; and 0.5-1 part of an antioxidant. According to the leaky coaxial cable, the raw materials of the outer sheath in the leaky coaxial cable are adjusted, so that the problem that the grade of combustion drippings / particles is mostly d1 or d2 and cannot reach the grade d0 when the leaky coaxial cable is subjected to a B1-grade combustion test at present can be solved. The B1-level flame-retardant non-dripping high-performance transmission leaky coaxial cable can be widely applied to signal system construction of various large railway tracks at home and abroad, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of leaky coaxial cables, and in particular relates to a B1-level flame-retardant, non-drip high-performance transmission leaky coaxial cable and a manufacturing method thereof. Background Art

[0002] Leaky coaxial cable (referred to as "leaky cable") is suitable for closed environments where external radio signals cannot reach, such as subways, mines, tunnels, and buildings, and has the dual functions of signal transmission and antenna. With the country's increasing attention to fire protection and safety in the past two years, the flame retardant requirements for leaky cables have become increasingly higher.

[0003] In 2023, the Ministry of Housing and Urban-Rural Development issued the mandatory national standard GB55037-2022 "General Code for Building Fire Protection". More importantly, Section 10.2.2 of the above national standard stipulates that data communication cables in subway projects should use cables with a combustion performance not lower than Class B1. To this end, major domestic manufacturers are actively developing Class B1 flame-retardant leaky coaxial cables to adapt to market changes.

[0004] However, flame retardant materials and processing methods have a great impact on the electrical performance indicators of leaky cables. While affecting the electrical transmission performance of leaky cables, in the B1 level combustion test, the burning dripping / particle level is mostly d1 or d2, which cannot meet the requirements of d0 level. In view of the above technical difficulties in the industry, a B1 level flame retardant non-drip high-performance transmission leaky coaxial cable is urgently needed. Summary of the invention

[0005] The present invention aims to provide a B1-class flame-retardant, non-drip, high-performance transmission leakage coaxial cable and a manufacturing method thereof, by adjusting the composition of the outer sheath and the manufacturing process to improve the flame retardant and electrical properties of the cable.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A B1-level flame-retardant, drip-free, high-performance transmission leaky coaxial cable comprises, from inner layer to outer layer, an inner conductor, an insulating layer, an outer conductor, a tape layer and an outer sheath.

[0008] Specifically, the inner conductor is a spiral copper tube or a smooth copper tube.

[0009] Specifically, the insulating layer is arranged outside the inner conductor by extrusion.

[0010] Specifically, the insulating layer is a foamed polyethylene insulating layer.

[0011] Specifically, the outer conductor is a corrugated copper strip or aluminum strip with leakage slots.

[0012] Specifically, the tape layer is arranged outside the outer conductor in an overlapping wrapping or longitudinal wrapping manner.

[0013] Specifically, the wrapping layer is made of pure glass fiber tape or fireproof tape, and its temperature resistance level is 550-1200°C.

[0014] Specifically, the outer sheath layer is made of a low-smoke, halogen-free flame-retardant sheath material with high crack resistance, high flame retardancy, good crusting performance and high physical and mechanical properties.

[0015] Further preferably, the wrapping layer is made of pure glass fiber tape or fireproof tape with a relatively high weaving density, which can fit closely with the outer sheath during the production process and improve the dripping performance of the outer sheath when it burns.

[0016] Furthermore, the outer sheath is prepared from the following raw materials (parts by weight):

[0017] EVA (ethylene-vinyl acetate copolymer) 10-20 parts; POE polyolefin elastomer 10-20 parts; maleic anhydride grafted polyethylene 5-10 parts; metal hydroxide 50-70 parts; processing aid 0.5-2 parts; antioxidant 0.5-1 part.

[0018] Specifically, the weight content of VA (vinyl acetate) in the EVA is 18-40%, and the melt flow rate at 190° C. / 2.16 kg is 1-7 g / min.

[0019] Specifically, the POE polyolefin elastomer is one or more of ethylene-octene copolymer, ethylene-propylene copolymer and ethylene-butene copolymer, and has a melt flow rate of 1-5 g / min at 190° C. / 2.16 kg.

[0020] Specifically, the metal hydroxide is one or both of aluminum hydroxide and magnesium hydroxide, and the average particle size D50 is 1 to 2 um.

[0021] Specifically, the processing aid is one or a combination of PE wax, stearic acid, and silicone masterbatch.

[0022] Specifically, the antioxidant is a mixture of one or two of antioxidant 1010 and antioxidant 168; preferably, when the antioxidant is a mixture of antioxidant 1010 and antioxidant 168, the mass ratio of the two is (1-2):1.

[0023] Specifically, the preparation method of the outer sheath is:

[0024] According to the weight ratio, each component is added to a high-speed mixer, stirred and mixed evenly, then added to an internal mixer for mixing, and then subjected to twin-screw extrusion, pelletizing, and cooling to finally prepare the outer sheath.

[0025] Specifically, the internal mixer has a finishing temperature of 150-180°C, and the twin-screw extruder has a finishing temperature of 100-140°C.

[0026] Furthermore, the present invention also provides a method for manufacturing the B1-level flame-retardant, drip-free, high-performance transmission leaky coaxial cable, comprising the following steps:

[0027] (1) Preparation of insulating layer: producing the insulating layer by extrusion equipment and coating the inner conductor;

[0028] (2) Preparing an outer conductor layer: an outer conductor is arranged outside the insulating layer, and is longitudinally wrapped onto the insulating layer through a longitudinally wrapped speaker mold; the longitudinally wrapped speaker mold and the longitudinally wrapped method are conventional methods in the prior art, and are not the invention of the present invention, and will not be described in detail here;

[0029] (3) preparing a tape layer: a tape layer is arranged outside the outer conductor layer, and the tape layer is wrapped around the outer conductor layer by a concentric wrapping machine; the concentric wrapping machine and the wrapping method are conventional methods in the prior art, and are not the invention of the present invention, and will not be described in detail here;

[0030] (4) Preparation of outer sheath layer: The outer sheath layer is produced by an extruder outside the tape layer, and one or two marking lines are set on the outer sheath at the seam of the outer conductor of the tape layer to mark the installation direction of the leaky cable, thus completing the manufacture of the leaky coaxial cable.

[0031] Specifically, in step (4), the extrusion temperature is controlled at 140-160°C.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention can improve the influence of raw materials on electrical performance indicators such as attenuation, coupling, and standing wave of the leaky coaxial cable by adjusting the raw materials of the inner and outer sheaths of the leaky coaxial cable.

[0034] 2. The present invention adjusts the raw materials of the inner and outer sheaths of the leaky coaxial cable, thereby solving the problem that the level of burning drips / particles of the leaky coaxial cable is mostly at d1 or d2 and cannot reach d0 level during the B1 level combustion test.

[0035] 3. The present invention can ensure the transmission performance and B1-level flame retardant performance of the cable by reasonably designing the cable structure.

[0036] 4. The present invention improves the production method, thereby improving the dripping performance of the outer sheath during combustion and ensuring that the d0 level requirement is met.

[0037] 5. Compared with the prior art, the present invention can achieve a limiting oxygen index of more than 38 by adding a large amount of flame retardants and synergistic flame retardancy of multiple flame retardants, thereby improving the flame retardant performance of the material, meeting the requirements of various types of leaky cables through bundled combustion, and can also reach the B1 level in GB 31247-2014, and the level requirement of burning droplets / particles in the B1 level can reach the d0 level. The total amount of smoke produced by the leaky cable during combustion and the smoke production rate during the combustion process are greatly reduced, and the minimum light transmittance of the optical cable can reach more than 60%; in addition, the smoke released by the combustion can reach the t0 level in the smoke toxicity level requirement in GB 31247-2014; the gas produced by the combustion is almost non-corrosive, and the corrosive level requirement in GB 31247-2014 can reach the a1 level.

[0038] 6. The B1-level flame-retardant, drip-free, high-performance transmission leakage coaxial cable of the present invention can be widely used in the construction of signal systems of major railway tracks at home and abroad, with stable indicators and superior performance, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a cross-sectional schematic diagram of the B1-level flame-retardant, non-drip high-performance transmission leaky coaxial cable of the present invention;

[0040] In the figure: 1. inner conductor; 2. insulation layer; 3. outer conductor; 4. tape layer; 5. outer sheath. DETAILED DESCRIPTION

[0041] The technical solution of the present application is described clearly and completely below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0042] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0043] Unless otherwise specified, the process methods involved in the following examples are all conventional methods; the process equipment used in the following examples are all commercially available conventional process equipment unless otherwise specified; the reagents, raw materials, etc. used in the following examples are all conventional commercially available products and can be obtained from commercial channels unless otherwise specified.

[0044] Example 1

[0045] like Figure 1 As shown, Example 1 proposes a B1-level flame-retardant, non-drip high-performance transmission leaky coaxial cable, which comprises, from inner layer to outer layer, an inner conductor 1, an insulating layer 2, an outer conductor 3, a tape layer 4, and an outer sheath 5.

[0046] The inner conductor 1 is a spiral copper tube or a smooth copper tube;

[0047] The insulating layer 2 is arranged outside the inner conductor 1 by extrusion;

[0048] The insulating layer 2 is a foamed polyethylene insulating layer, which is obtained by a method of integrally forming an inner skin layer, a foamed layer and an outer skin layer, that is, a skin-foam-skin structure, which can make the inner conductor 1 or the outer conductor 3 tightly bonded to the insulator of the insulating layer 2;

[0049] The outer conductor 3 is a corrugated copper strip or aluminum strip with leakage slots, and the structural dimensions of the slots can be adjusted according to the use requirements under different working frequencies.

[0050] The outer conductor 3 is arranged in such a way that the outer conductor 3 strip having the grooves punched by the groove punching equipment is longitudinally wrapped onto the insulating layer 2 through a longitudinal wrapping speaker mold.

[0051] The tape layer 4 is disposed outside the outer conductor 3 in an overlapping wrapping or longitudinal wrapping manner.

[0052] The wrapping layer 4 is made of pure glass fiber tape or fireproof tape, and its temperature resistance level is 550-1200° C. Its surface is not dipped in a flame retardant mixture solution of a high-efficiency inorganic flame retardant, and its components do not affect the transmission performance of the leaky cable.

[0053] The five layers of the outer sheath are made of low-smoke, halogen-free flame-retardant sheath material with high crack resistance, high flame retardancy, good crusting performance and high physical and mechanical properties.

[0054] Further preferably, the wrapping layer 4 is made of pure glass fiber tape or fireproof tape with a relatively high weaving density, which can fit closely with the outer sheath 5 during the production process and improve the dripping performance of the outer sheath 5 when it burns.

[0055] Specifically, the raw material formula (parts by weight) of the outer sheath 5 is:

[0056] EVA (ethylene-vinyl acetate copolymer) 20 parts; POE polyolefin elastomer 20 parts; maleic anhydride grafted polyethylene PE-g-MAH 10 parts; metal hydroxide (flame retardant) 50 parts; processing aid 0.5 parts; antioxidant 0.5 parts;

[0057] The weight content of VA (vinyl acetate) in the EVA is 18-40%, and the melt flow rate at 190°C / 2.16kg is 1-7g / min;

[0058] The POE polyolefin elastomer is an ethylene-octene copolymer, and the melt flow rate at 190°C / 2.16kg is 1-5g / min;

[0059] Maleic anhydride grafted polyethylene PE-g-MAH, the grafting rate is 0.4-1%;

[0060] The metal hydroxide is aluminum hydroxide, and the average particle size D50 is 1 to 2 um;

[0061] The processing aid is PE wax;

[0062] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168, and the mass ratio thereof is 2:1.

[0063] Specifically, the preparation method of the outer sheath 5 is:

[0064] According to the weight ratio, each component is added to a high-speed mixer, stirred and mixed evenly, then added to an internal mixer for mixing, and then subjected to twin-screw extrusion, pelletizing, and cooling to finally prepare the outer sheath 5.

[0065] Among them, the internal mixer completion temperature is 180℃ and the twin-screw extrusion temperature is 100℃.

[0066] Specifically, the outer sheath 5 is extruded in an extrusion manner, and a suitable mold is reasonably designed according to the outer diameter of the cable for extrusion, which can effectively ensure the flame retardant and non-drip performance of the cable; the mold includes a mold core and a mold sleeve.

[0067] Specifically, during extrusion, taking the leaky coaxial cable of model WDZ-SLYWY-50-42-III as an example, the nominal outer diameter of the cable before extrusion is 44.5mm, and the outer sheath 5 is required to have a nominal thickness of 1.9mm and a minimum thickness of 1.7mm. To ensure a better extrusion effect, the inner diameter of the mold core is 45.50mm, and the length of the mold core sizing zone is 20mm; the outer taper angle of the mold core is 37°20′; the length of the mold sleeve sizing zone is 3mm, the diameter of the mold sleeve sizing zone is 48.0mm, and the inner taper angle of the mold sleeve is 45°22′. By using this mold, the outer sheath 5 of the cable can be tightly combined with the tape layer 4. When burning, the outer sheath 5 can effectively stick to the glass fiber tape, ensuring flame retardant properties and non-drip properties.

[0068] The manufacturing method of the B1-level flame-retardant, non-drip high-performance transmission leaky coaxial cable comprises the following specific steps:

[0069] (1) Preparing an insulating layer: producing an insulating layer 2 by an extrusion device and coating the inner conductor 1, wherein the insulating layer 2 is a foamed polyethylene insulating layer, and the foamed polyethylene insulating layer is integrated with an inner skin layer, a foamed layer and an outer skin layer, i.e., a skin-foam-skin structure, which can make the inner conductor 1 and the insulating layer 2 tightly bonded;

[0070] (2) Preparing an outer conductor layer: an outer conductor 3 is arranged outside the insulating layer 2, and the outer conductor 3 is a corrugated copper strip or aluminum strip with leakage slots, and is longitudinally wrapped on the insulating layer 2 through a longitudinal wrapping speaker mold; the longitudinal wrapping speaker mold and the longitudinal wrapping method are conventional methods in the prior art, and are not the invention of the present invention, and will not be described in detail here. For details, please refer to the document (CN202011173210.2 A method for longitudinally wrapping a cable metal strip);

[0071] (3) Preparing a tape layer: a tape layer 4 is arranged outside the three layers of the outer conductor, the tape layer 4 is made of pure glass fiber tape or fireproof tape, and the tape layer 4 is overlapped and wrapped outside the three layers of the outer conductor by a concentric wrapping machine; the concentric wrapping machine and the wrapping method are both conventional methods in the prior art, and are not the invention of the present invention, and will not be described in detail here. For details, please refer to the literature (CN202223489233.1 a concentric wrapping machine, CN201320393890.8 a concentric vertical wrapping machine);

[0072] (4) Preparation of outer sheath layer: an outer sheath 5 layer is produced outside the tape layer 4 by an extruder, and the extrusion temperature is controlled at 140-160°C. One or two marking lines are set on the outer sheath 5 at the joint of the outer conductor 3 wrapped around the tape layer 4 to mark the installation direction of the leaky cable, and the manufacture of the leaky coaxial cable is completed.

[0073] Performance test (test method reference standard TB / T3201 "Railway communication leaky coaxial cable"):

[0074] (I) Electrical performance test

[0075] Taking the conventional large iron WDZ-SLYWYY-50-42-III type leaky cable as an example, the test results are shown in Table 1.

[0076] Table 1

[0077]

[0078] It can be seen from Table 1 that, compared with the prior art, the transmission performance of the leaky coaxial cable described in Example 1 of the present invention is attenuated, while the coupling loss and standing wave performance are not affected.

[0079] (II) Combustion test

[0080] The test results are shown in Table 2.

[0081] Table 2 Performance data after B1 level combustion test

[0082]

[0083]

[0084] It can be seen from Table 2 that, compared with the prior art, the leaky coaxial cable of Example 1 of the present invention can reach the B1 level in GB31247-2014, and the level requirement of burning droplets / particles in the B1 level can reach the d0 level. The total amount of smoke produced by the leaky cable during combustion and the smoke production rate during the combustion process are greatly reduced, and the minimum light transmittance of the cable can reach more than 60%; in addition, the smoke released by the combustion can reach the t0 level in the smoke toxicity level requirement in GB 31247-2014; the gas produced by the combustion is almost non-corrosive, and the corrosive level requirement in GB 31247-2014 can reach the a1 level.

[0085] Example 2

[0086] Example 2 proposes a B1-level flame-retardant, non-drip, high-performance transmission leaky coaxial cable. The cable described in Example 2 is different from that described in Example 1 in that:

[0087] The raw material formula (weight parts) of the outer sheath 5 is:

[0088] EVA (ethylene-vinyl acetate copolymer) 10 parts; POE polyolefin elastomer 10 parts; maleic anhydride grafted polyethylene PE-g-MAH 5 parts; metal hydroxide (flame retardant) 70 parts; processing aid 2 parts; antioxidant 1 part;

[0089] The metal hydroxide is magnesium hydroxide, and the average particle size D50 is 1 to 2 um;

[0090] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168, and the mass ratio thereof is 1:1.

[0091] Specifically, in the preparation method of the outer sheath 5, the internal mixer finishing temperature is 150°C, and the twin-screw extrusion temperature is 140°C.

[0092] The manufacturing method in Example 2 is the same as that in Example 1.

[0093] After testing, the B1-level flame-retardant and non-drip high-performance transmission leaky coaxial cable manufactured in Example 2 also has good electrical properties and flame-retardant properties, and its performance is equivalent to that of Example 1.

[0094] In summary, compared with the prior art, the present invention can achieve a limiting oxygen index of more than 38 through the addition of a large amount of flame retardants and the synergistic flame retardancy of multiple flame retardants, thereby improving the flame retardant performance of the material, and can meet the requirements of various types of leaky cables through bundled combustion, and can also reach the B1 level in GB 31247-2014, and the level requirement of burning droplets / particles in the B1 level can reach the d0 level. The total amount of smoke produced by the leaky cable during combustion and the smoke production rate during the combustion process are greatly reduced, and the minimum light transmittance of the optical cable can reach more than 60%; in addition, the smoke released by the combustion can reach the t0 level in the smoke toxicity level requirement in GB 31247-2014; the gas produced by the combustion is almost non-corrosive, and the corrosive level requirement in GB 31247-2014 can reach the a1 level.

[0095] The above embodiments are examples of the implementation methods of the present invention, and the implementation methods of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A B1 flame retardant, drip-free, high-performance transmission leaky coaxial cable, characterized in that: From inner to outer layers, they are inner conductor, insulation layer, outer conductor, tape layer, and outer sheath.

2. The B1-level flame-retardant, non-drip high-performance transmission leaky coaxial cable according to claim 1, characterized in that: The inner conductor is a spiral copper tube or a smooth copper tube; The insulating layer is arranged outside the inner conductor by extrusion; The outer conductor is a corrugated copper strip or aluminum strip with leakage slots; The tape layer is arranged outside the outer conductor in an overlapping wrapping or longitudinal wrapping manner.

3. The B1-class flame-retardant, non-drip high-performance transmission leaky coaxial cable according to claim 1 or 2, characterized in that: The outer sheath is prepared from the following raw materials in parts by weight: 10-20 parts of ethylene-vinyl acetate copolymer EVA; 10-20 parts of POE polyolefin elastomer; 5-10 parts of maleic anhydride grafted polyethylene; 50-70 parts of metal hydroxide; 0.5-2 parts of processing aid; 0.5-1 part of antioxidant.

4. The B1-level flame-retardant, non-drip high-performance transmission leaky coaxial cable as claimed in claim 3, characterized in that: The POE polyolefin elastomer is one or more of ethylene-octene copolymer, ethylene-propylene copolymer and ethylene-butene copolymer.

5. The B1-level flame-retardant, non-drip high-performance transmission leaky coaxial cable as claimed in claim 3, characterized in that: The metal hydroxide is one or both of aluminum hydroxide and magnesium hydroxide; The processing aid is one or a combination of PE wax, stearic acid, and silicone masterbatch; The antioxidant is one or a mixture of two of antioxidant 1010 and antioxidant 168.

6. The B1-level flame-retardant, non-drip high-performance transmission leaky coaxial cable as claimed in claim 3, characterized in that: The preparation method of the outer sheath is: The components are uniformly mixed according to the weight ratio, and then kneaded, and then subjected to twin-screw extrusion, pelletizing, and cooling to finally prepare the outer sheath.

7. The B1-level flame-retardant, non-drip high-performance transmission leaky coaxial cable according to claim 6, characterized in that: The mixing is carried out using an internal mixer, the completion temperature is 150-180°C, and the twin-screw extrusion temperature is 100-140°C.

8. The method for manufacturing a Class B1 flame-retardant, non-drip high-performance transmission leaky coaxial cable as claimed in any one of claims 1 to 7, characterized in that: The steps include: (1) Preparation of insulating layer: The insulating layer is produced by extrusion equipment and covered on the outside of the inner conductor; (2) Preparing an outer conductor layer: Arrange an outer conductor outside the insulating layer and wrap it longitudinally onto the insulating layer through a longitudinally wrapped speaker mold; (3) Preparing a tape layer: a tape layer is arranged outside the outer conductor layer, and the tape layer is overlapped and wrapped around the outer conductor layer by a concentric wrapping machine; (4) Preparation of outer sheath layer: The outer sheath layer is produced outside the tape layer by an extruder, thus completing the manufacture of the leaky coaxial cable.

9. The manufacturing method according to claim 8, characterized in that: In step (4), the extrusion temperature is controlled at 140-160°C.

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