Low-smoke halogen-free flame-retardant physical termite-proof aluminum sheath type cable

Abstract

The utility model belongs to the technical field of cable production and processing technology, and particularly relates to a low-smoke halogen-free flame-retardant physical termite-proof aluminum sheath type cable. The utility model relates to a low-smoke halogen-free flame-retardant physical termite-proof aluminum sheath type cable which sequentially comprises a cable core, a PE (polyethylene) heat insulation layer, an aluminum sheath, an inner cushion layer, a steel tape armor layer, an inner-layer outer sheath and an outer-layer outer sheath from the inner layer to the outer layer. By adjusting the composition of the inner cushion layer, the inner-layer outer sheath and the outer-layer outer sheath in the cable and adopting a specific production process, the prepared cable has excellent flame-retardant, electrical and physical properties, the flame-retardant property meets the A-class flame-retardant grade requirement, and the flame-retardant property meets the A-class flame-retardant grade requirement. The physical termite prevention performance reaches group method evaluation and ant nest method evaluation. The low-smoke halogen-free flame-retardant physical termite-proof aluminum sheath type cable provided by the utility model can be widely applied to signal system construction of various large railway tracks at home and abroad, is stable in index and excellent in performance, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The utility model belongs to cable production and processing process technical field, concretely relates to a kind of low-smoke halogen-free flame-retardant physical termite prevention aluminium sheath type cable, and the cable is applicable to railway signal transmission system. BACKGROUND

[0002] Cables are made of one or more insulated conductors and outer insulation protection layer, which transmit power or information from one place to another. Insulated cables are made of one or more insulated cores, and their respective possible cladding layers, total protection layers and outer sheaths, to transmit power, information and realize electromagnetic energy conversion.

[0003] The outer sheath layer of the cable is prone to biological damage, especially termite damage in southern areas. The outer sheath of high-voltage cable is the first line of defense for the normal operation of the cable. Due to the gnawing of termites, the outer sheath of the cable is easily damaged, causing the cable insulation to be damp, leading to a decrease in insulation resistance, causing single-phase grounding short circuit, and even causing line breakdown and other serious accidents. Therefore, improving the performance of the outer sheath of high-voltage cable, preventing termite damage and ensuring the safe operation of the cable have become urgent research content for cable manufacturing enterprises and power departments.

[0004] In the prior art, termite prevention cables mainly use chemical methods to prevent termites. Chemical agents are added to the outer sheath material to kill or avoid termites when they approach or gnaw the outer sheath. Chemical termite prevention can cause allergic reactions and even stress in direct contact with the human body during actual production and laying. In severe cases, it can even lead to death. At the same time, the termite prevention effect of chemical additives tends to weaken over time. Therefore, in recent years, the industry has generally required the use of physical termite prevention methods to replace chemical methods to reduce human and environmental hazards.

[0005] In the prior art, common termite prevention cable products are mainly non-flame-retardant. With the development of the industry, the demand for flame-retardant products has also significantly expanded, such as expanding the original single vertical burning to bundled Class C, Class B or even Class A. The inventor found in previous research that there are many nylon manufacturers on the market that meet the conventional performance, but there are few flame-retardant nylon manufacturers and flame-retardant nylon cable products that meet the bundled burning and light transmission rate.

[0006] In view of the above situation, there is an urgent need for a cable product that can physically prevent termites and also has low smoke and flame-retardant properties, while also meeting the requirements of related electrical properties, corrosion resistance and other requirements. UTILITY MODEL CONTENT

[0007] The utility model aims at providing a kind of low smoke halogen-free flame-retardant physical termite prevention aluminium sheath type cable, by adjusting the composition of inner pad layer, inner layer outer sheath, outer layer outer sheath in cable, and using specific production process, the cable prepared has excellent flame-retardant, electrical performance and physical performance, in addition, it also has physical termite prevention function, can reach termite comprehensive management and termite prevention standard in termite hazard area, with good application prospect.

[0008] In order to realize the above-mentioned purpose, the utility model adopts following technical solutions:

[0009] A kind of low smoke halogen-free flame-retardant physical termite prevention aluminium sheath type cable, from inner layer to outer layer in order cable core, PE heat insulation layer, aluminium sheath, inner pad layer, steel belt armoring layer, inner layer outer sheath and outer layer outer sheath.

[0010] Specifically, the cable core is made of a plurality of core units by twisting, each core unit is made of a plurality of insulated single wires twisted and wrapped with a layer of glass cloth tape, preferably, the cable core is a four-core cable core, which is made of four core units by twisting.

[0011] Specifically, the glass cloth tape is woven with inorganic glass fiber fabric, which can tighten and insulate.

[0012] Specifically, each insulated single wire is made of a conductor and an insulating layer coated on the outer surface of the conductor, and the insulating layer has different colors.

[0013] Specifically, a soft copper wire meeting the requirements of GB / T 3953-2024 Electrical Copper Wire is selected as the conductor, and the nominal diameter of the conductor is 1.0 mm.

[0014] Specifically, the insulating layer is made of polyethylene insulating material (model C S K-3364NT CPD 3364).

[0015] Specifically, the insulating layer has four colors: red, green, white and blue; the nominal thickness of the insulating layer is 0.6 mm, and the allowable deviation is ±0.1 mm.

[0016] Specifically, the twisting method of the core unit is paired or star twisting.

[0017] The paired twisting is made of paired wire groups, each paired wire group is made of two insulated single wires of different colors twisted and wrapped with a layer of glass cloth tape, and the twisting pitch is not greater than 300 mm; the paired wire group color spectrum is red / white, green / white, blue / green and blue / white.

[0018] The star quad type is made of star quad cable core units, each of which is made of four insulated single wires of different colors which are left-twisted and wrapped with a glass cloth tape layer, and the twisting pitch is not greater than 300mm; the star quad units with different twisting pitches should be wound with non-hygroscopic wires of different colors; the A-end line sequence arrangement of the star quad unit should meet the requirements of TB / T 2476-2017 Railway Signal Cable.

[0019] The requirements of TB / T 2476-2017 Railway Signal Cable.

[0020] Preferably, the four-core cable core is made of four star quad cable core units by left-twisting, or the four-core cable core is made of four pair cable core units by left-twisting.

[0021] Specifically, a non-woven fabric wrapping tape is further arranged between the PE thermal insulation layer and the cable core, and the non-woven fabric wrapping tape is arranged outside the cable core by wrapping.

[0022] Specifically, the PE thermal insulation layer is arranged outside the non-woven fabric wrapping tape by extrusion.

[0023] Specifically, the inner pad layer is arranged outside the aluminum sheath by extrusion.

[0024] Specifically, the low-smoke halogen-free flame-retardant oxygen barrier sheath material (oxygen index ≥40) is used as the inner pad layer in the utility model, the low-smoke halogen-free flame-retardant oxygen barrier sheath material has good flame-retardant, fire-resistant and burning shell characteristics, and has more excellent performance of blocking heat transfer, blocking combustible materials and oxygen.

[0025] Further, the inner pad layer is prepared from the following weight ratio of raw materials: ethylene-vinyl acetate copolymer EVA 5-10 parts, high-density polyethylene HDPE 20-30 parts, compatibilizer 5-10 parts, flame retardant I 80-90 parts, shell forming agent 2-7 parts, antioxidant 0.2-0.5 parts, lubricant 1-4 parts and coupling agent 0.4-3 parts.

[0026] Further, the compatibilizer can be one or more of a mixture of cyclic anhydride compatibilizer, epoxy compatibilizer and oxazoline compatibilizer; the compatibilizer is preferably a cyclic anhydride compatibilizer, which can be one or more of a mixture of maleic anhydride grafted styrene-ethylene-butadiene-styrene block copolymer (SEBS-g-MAH, where SEBS is linear and star type, preferably linear SEBS, molecular weight ≥70000), maleic anhydride grafted ethylene-octene copolymer (POE-g-MAH) and maleic anhydride grafted ethylene-vinyl acetate copolymer (EVA-g-MAH), wherein the grafting rate of maleic anhydride (MAH) is 0.5%-3%.

[0027] Further, the flame retardant I is one or more of aluminum hydroxide, magnesium hydroxide, magnesium oxide, antimony trioxide, sodium tetraborate.

[0028] Further, the coupling agent is one or more of silane coupling agents such as KH560, KH550, KH570, KH792, DL602, or is one or more of titanate coupling agents such as 201, 101, 105, 311, and is preferably the silane coupling agent KH550.

[0029] Further, the antioxidant is one or more of antioxidant 168, antioxidant 1010, antioxidant 1076, antioxidant 1098, antioxidant 3114, antioxidant 164, antioxidant 264, antioxidant BHT, antioxidant T501, antioxidant B215, and antioxidant B225.

[0030] Further, the shell-forming agent is any one or mixture of two of modified nanometer montmorillonite, silicon powder, white carbon black, and can also be a complex flame retardant containing at least boracite and organic montmorillonite, or a polyphosphate flame retardant PX-220.

[0031] Further, the modified nanometer montmorillonite is obtained by mixing hexadecane with montmorillonite, and the mass ratio of hexadecane to montmorillonite is (0.5-2):1.

[0032] Further, the lubricant is any one or mixture of two or more of polyethylene wax, stearate, ethylene bis-stearamide, vinyl tri(β-methoxyethoxy) silane (A172), polydimethylsiloxane, silicone, methyl silicone oil, and paraffin oil.

[0033] Specifically, the stearate is any one of magnesium stearate, barium stearate, and calcium stearate.

[0034] Further, the utility model also provides a preparation method of the inner cushion layer, which comprises the following steps:

[0035] The raw materials of the inner cushion layer are mixed, and then kneaded by a banbury mixer at a temperature of 175-190 DEG C for 10-20 minutes, and then extruded and granulated by a single screw extruder at a temperature of 110-130 DEG C and a rate of 200-280 kg / hour.

[0036] Specifically, the inner layer outer sheath is arranged outside the steel belt armor layer in an extrusion coating manner, and an ultraviolet-resistant anti-cracking halogen-free low-smoke flame-retardant polyolefin outer sheath material is used as the inner layer outer sheath, which has better performance of blocking heat transfer and cutting off combustible materials and oxygen.

[0037] Specifically, the outer layer outer sheath is arranged outside the inner layer outer sheath in an extrusion manner, and a flame-retardant nylon sheath material is used as the outer layer outer sheath. The material has excellent heat transfer blocking, combustible and oxygen blocking performance, and also has physical termite prevention function, can reach the termite comprehensive control and termite prevention standard in the termite hazard area described in GB / T50768-2012 Termite Control Engineering, and improve the safety and reliability of railway signal line operation, and the physical termite prevention performance reaches the group evaluation and nest evaluation.

[0038] Further, the outer layer outer sheath is prepared from the following weight ratio of raw materials: 60-90 parts of flame-retardant nylon PA12 resin, 1-10 parts of plasticizer, 1-5 parts of char-forming agent, 0.1-2 parts of antioxidant, 0.1-2 parts of ultraviolet inhibitor, 0.1-1 parts of lubricant, and 10-30 parts of flame retardant II.

[0039] Further, the plasticizer is a combination of one or more of trioctyl trimellitate, tridecyl trimellitate, and polyester plasticizer.

[0040] Further, the char-forming agent is a phosphate ester and its derivative, preferably pentaerythritol phosphate.

[0041] Further, the antioxidant is one or a mixture of two or more of antioxidant 1010 (tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester), antioxidant 168 (tris(2,4-di-tert-butylphenyl) phosphite), antioxidant 300, antioxidant DLTP (dilauryl thiodipropionate), antioxidant TPP, and triphenylmethyl phosphate.

[0042] Further, the ultraviolet inhibitor is a hindered amine light stabilizer, preferably hindered amine light stabilizer HS-944 or HPHA (hydroxypropyl hydroxylamine), or the ultraviolet inhibitor can also be other light stabilizers, such as a combination of one or more of n-2-hydroxy-4-n-octyloxybenzophenone (UV-531), 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (UV-P), and 2,2'-thiobis(4-tert-octylphenyloxy)nickel (AM-101).

[0043] Further, the lubricant is any one or a mixture of two or more of polyethylene wax, stearate, ethylene bis-stearamide, vinyl tri(β-methoxyethoxy)silane (A172), polydimethylsiloxane, silicone, methyl silicone oil, and paraffin oil.

[0044] Specifically, the stearate is any one of magnesium stearate, barium stearate, and calcium stearate.

[0045] Further, the flame retardant II is a phosphorus-nitrogen flame retardant, and its components include: ADP (aluminum diethyl phosphinate) 6-21 parts, MPP (melamine polyphosphate) 2-7 parts, zinc borate 1-3.5 parts.

[0046] Further, the utility model further provides production process of low smoke halogen-free flame retardant physical termite prevention aluminum sheath type cable, including following steps:

[0047] S1 cable core making: the cable core is made by a plurality of cable core units in the way of twisting, and each cable core unit is made by twisting a plurality of insulated single wires and wrapping a layer of glass cloth tape outside;

[0048] The glass cloth tape is wrapped by inorganic glass fiber woven cloth, which can play the role of tightening and heat insulation;

[0049] Soft round copper wire is selected as the conductor, and different colored insulation layers are coated on a plurality of conductors during specific manufacturing to obtain insulated single wires coated with red, green, white and blue insulation layers respectively;

[0050] S2 cable forming: the manufactured cable has two forming modes, one is a pair-twisted type, and the other is a star-twisted type;

[0051] The pair-twisted type is made of pair line groups of cable core units, and each pair line group of cable core unit is made by twisting two insulated single wires of different colors in step S1 and wrapping a layer of glass cloth tape outside;

[0052] The star-twisted type is made of star type four line groups of cable core units, and each star type four line group of cable core unit is made by twisting four insulated single wires of different colors in step S1 and wrapping a layer of glass cloth tape outside;

[0053] Then, the four pair line groups of cable core units or the four star type four line groups of cable core units are twisted to form a cable core;

[0054] S3 PE heat insulation layer making: the PE heat insulation layer is made outside the non-woven fabric wrapping tape by extrusion;

[0055] S4 aluminum sheath making: the aluminum sheath is made outside the PE heat insulation layer by coating;

[0056] S5 inner pad layer making: the inner pad layer is made outside the aluminum sheath by extrusion;

[0057] S6 armoring: the steel tape armoring layer is made outside the inner pad layer by wrapping;

[0058] S7 inner layer outer sheath making: the inner layer outer sheath is made outside the steel tape armoring layer by extrusion;

[0059] S8 manufacturing outer layer outer sheath: the outer layer outer sheath is manufactured outside the inner layer outer sheath by extrusion;

[0060] Thus, the manufacturing of the cable is completed.

[0061] Specifically, in step S1, the conductor has a nominal diameter of 1.0 mm.

[0062] Specifically, in step S1, the insulation layer has a nominal thickness of 0.6 mm and an allowable deviation of ±0.1 mm.

[0063] Specifically, in step S1, the insulation layer is made of polyethylene insulation material with a model number of CS K-3364NT CPD.

[0064] Specifically, in step S2, the twisting pitch is not greater than 300 mm.

[0065] Specifically, in step S2, a non-woven fabric tape can be further wrapped around the cable core.

[0066] Specifically, in step S6, the steel strip armor layer is made of galvanized material, and the steel strip armor layer can be provided with two layers. The steel strip armor layer should meet the requirements of GB2952.2-1989 Cable Outer Sheath Metal Jacket Cable General Outer Sheath.

[0067] Compared with the prior art, the low-smoke halogen-free flame-retardant physical termite-resistant aluminum sheath type cable has the following beneficial effects:

[0068] The low-smoke halogen-free flame-retardant physical termite-resistant aluminum sheath type cable can be widely applied to the signal system construction of various large railways at home and abroad, has stable indicators, superior performance, and has a broad application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0069] Figure 1 is a cross-sectional schematic view of the low-smoke halogen-free flame-retardant physical termite-resistant aluminum sheath type cable of the utility model;

[0070] Figure 2 is a cable core cross-sectional schematic view of the cable made by the utility model in a star twisting manner;

[0071] Figure 3 is a cable core cross-sectional schematic view of the cable made by the utility model in a star twisting manner;

[0072] Figure 4 is a production process flow chart of the cable of the utility model;

[0073] In the diagram: 1. Cable core; 2. Non-woven tape; 3. PE insulation layer; 4. Aluminum sheath; 5. Inner padding layer; 6. Steel tape armor layer; 7. Inner outer sheath; 8. Outer outer sheath; 11. Conductor; 12. Insulation layer; 13. Cable core unit. Detailed Implementation

[0074] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0075] The structures, proportions, and sizes illustrated in the accompanying drawings are solely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0076] Example 1

[0077] like Figure 1 As shown in Example 1, a low-smoke, halogen-free, flame-retardant, physically termite-proof aluminum-sheathed cable is proposed. Its inner and outer layers are, in order, cable core 1, non-woven fabric wrapping tape 2, PE insulation layer 3, aluminum sheath 4, inner padding layer 5, steel tape armor layer 6, inner outer sheath 7, and outer outer sheath 8.

[0078] Specifically, the cable core 1 is made by twisting together several core units 13. Each core unit 13 is made by twisting together several insulated single wires and then wrapping them with a layer of glass cloth tape. Preferably, in this embodiment, the cable core 1 is a four-core cable core, that is, the cable core 1 is made by twisting together four core units 13.

[0079] The glass cloth tape layer is made of inorganic glass fiber woven tape wrapped around the surface, which can serve as a tight binding and heat insulation function.

[0080] Each insulated single wire is made of a conductor 11 and an insulating layer 12 coated on the outer surface of the conductor 11, the insulating layer 12 having a different color.

[0081] In this embodiment, the soft round copper wire in accordance with the provisions of GB / T 3953-2024 Electrical Round Copper Wire is selected as the conductor 11, and the nominal diameter of the conductor 11 is 1.0 mm.

[0082] Specifically, the insulating layer 12 adopts polyethylene insulating material (model: CS K-3364NT CPD 3364).

[0083] Specifically, the colors of the insulating layer 12 are red, green, white, and blue respectively, the nominal thickness of the insulating layer 12 is 0.6 mm, and the allowable deviation is ±0.1 mm.

[0084] Specifically, the stranding mode of the cable core unit 13 is a pair-stranded type or a star-stranded type.

[0085] The pair-stranded type is made of a pair-line group cable core unit 13, each pair-line group cable core unit 13 is made of two insulating single wires 13 of different colors which are left-stranded and then wrapped with a layer of glass cloth tape, and the stranding pitch is not greater than 300 mm; the pair-line group color spectrum is red / white, green / white, blue / green, and blue / white.

[0086] The star-stranded type is made of a star-type four-line group cable core unit 13, each star-type four-line group cable core unit 13 is made of four insulating single wires 13 of different colors which are left-stranded and then wrapped with a layer of glass cloth tape, and the stranding pitch is not greater than 300 mm; the star-type four-line group with different stranding pitches should be loosely wound with non-hygroscopic silk of different colors; the star-type four-line group A end line sequence arrangement should comply with the provisions of TB / T2476-2017 Railway Signal Cable.

[0087] As shown in FIG. 1, Figure 2 the star-stranded type, Figure 2 the four-core cable core 1 is made by left-stranding four star-type four-line group cable core units 13.

[0088] As shown in FIG. 2, Figure 3 the pair-stranded type, Figure 3 the four-core cable core 1 is made by left-stranding four pair-line group cable core units 13.

[0089] The cable core 1 adopts a core in accordance with the requirements of the railway signal cable standard (TB 2476.1~4-2017 Railway Signal Cable; TB 3100.1~6-2017 Railway Digital Signal Cable).

[0090] The non-woven fabric tape 2 is arranged outside the cable core 1 by winding.

[0091] The PE thermal insulation layer 3 is arranged outside the non-woven fabric tape 2 by extrusion.

[0092] The inner pad layer 5 is arranged outside the aluminum sheath 4 in an extrusion manner.

[0093] In the utility model, the low-smoke halogen-free flame-retardant oxygen barrier sheath material (oxygen index ≥40) is used as the inner pad layer 5, the low-smoke halogen-free flame-retardant oxygen barrier sheath material has good flame-retardant, fire-resistant and burning shell characteristics, and has more excellent performance of blocking heat transfer, blocking combustible material and oxygen.

[0094] Specifically, the inner pad layer 5 (low-smoke halogen-free flame-retardant oxygen barrier sheath material) is prepared from the following raw materials in parts by weight: ethylene-vinyl acetate copolymer EVA 5 parts, high-density polyethylene HDPE 20 parts, compatibilizer 5 parts, flame retardant I 80 parts, shell forming agent 2 parts, antioxidant 0.2 parts, lubricant 1 part and coupling agent 0.4 parts.

[0095] In the embodiment, the ethylene-vinyl acetate copolymer EVA has a model number of EVA7470k.

[0096] In the embodiment, the high-density polyethylene HDPE has a model number of plastic 3518; the high-density polyethylene is a white color wax-like material which is lighter than water, has a specific gravity of 0.941-0.960, is soft and flexible, is slightly harder and longer than LDPE, has no odor, can continue to burn after being removed from fire, has a yellow upper end and a blue lower end of flame, melts and has liquid dripping and no black smoke, and emits the odor of burning paraffin wax; the main advantages are resistance to organic solvents, excellent electrical insulation, and maintaining a certain flexibility at low temperature.

[0097] Preferably, the compatibilizer is maleic anhydride grafted ethylene-vinyl acetate copolymer (EVA-g-MAH), wherein the grafting rate of maleic anhydride (MAH) is 0.5%-3%.

[0098] The compatibilizer has important compatibility effect, can greatly improve the upper limit of the addition of the flame-retardant filler magnesium hydroxide, and improve the flame-retardant performance. In addition, the compatibilizer can also reduce the interfacial tension, increase the thickness of the interfacial layer, and reduce the size of the dispersed particles between different components, so that the system finally forms a thermodynamically stable phase structure with macroscopic uniformity and microscopic phase separation characteristics, thereby improving the mechanical properties of the material.

[0099] Preferably, the flame retardant I in the embodiment is aluminum hydroxide.

[0100] Preferably, the coupling agent in the embodiment is silane coupling agent KH550.

[0101] Preferably, the antioxidant in the inner pad layer 5 is antioxidant 1010.

[0102] Preferably, the lubricant in the inner pad layer 5 is magnesium stearate.

[0103] Preferably, the shell-forming agent in the embodiment is modified nano-montmorillonite.

[0104] The modified nano-montmorillonite is obtained by mixing hexadecane with montmorillonite, wherein the mass ratio of hexadecane to montmorillonite is 1:1.

[0105] In the preparation of the inner pad layer 5, the raw materials are mixed, then kneaded by a banbury mixer at a temperature of 175°C for 15 minutes, and then extruded and granulated by a single-screw extruder at a temperature of 110°C and a rate of 250 kg / hour.

[0106] The inner layer outer sheath 7 is arranged outside the steel belt armor layer 6 in the form of extrusion, and an ultraviolet-resistant anti-cracking halogen-free low-smoke flame-retardant polyolefin outer sheath material (mainly composed of polyolefin, smoke suppressant, aluminum hydroxide, magnesium hydroxide, calcium carbonate, carbon black, etc., which can be a conventional product in the prior art and is not the point of the present application, so it will not be described here) is used as the inner layer outer sheath 7. This material has more excellent performance in blocking heat transfer and cutting off combustible materials and oxygen.

[0107] The outer layer outer sheath 8 is arranged outside the inner layer outer sheath 7 in the form of extrusion, and a flame-retardant nylon sheath material is used as the outer layer outer sheath 8. This material has excellent performance in blocking heat transfer and cutting off combustible materials and oxygen, and has physical termite prevention function, which can meet the comprehensive termite control and termite prevention standards in the termite hazard areas described in GB / T50768-2012 Termite Control Engineering, improve the safety and reliability of railway signal line operation, and the physical termite prevention performance reaches the group evaluation and nest evaluation.

[0108] Specifically, the outer layer outer sheath 8 (flame-retardant nylon sheath material) is prepared from the following raw materials in parts by weight: flame-retardant nylon PA12 resin 60 parts, plasticizer 1 part, char-forming agent 1 part, antioxidant 0.1 part, ultraviolet-resistant agent 0.1 part, lubricant 0.1 part, and flame retardant II 10 parts.

[0109] The flame retardant II is a phosphorus-nitrogen flame retardant, and its components include ADP (aluminum diethyl phosphinate) 6 parts, MPP (melamine polyphosphate) 2 parts, and zinc borate 1 part.

[0110] Preferably, the plasticizer in the embodiment is trioctyl trimellitate.

[0111] Preferably, the char-forming agent in the embodiment is pentaerythritol phosphate.

[0112] Preferably, the antioxidant in the outer sheath 8 is DLTP (dilauryl thiodipropionate).

[0113] Preferably, in this embodiment, the UV stabilizer is a hindered amine light stabilizer, and more preferably the hindered amine light stabilizer HPHA (hydroxypropyl hydroxylamine).

[0114] Preferably, the lubricant in the outer sheath 8 is polyethylene wax.

[0115] The flame-retardant nylon PA12 resin described in this embodiment is model PA12-Z02, which is a halogen-free flame-retardant nylon 12 sheath material designed specifically for extrusion processing and can be used for optical cables and wires and cables. The properties of the flame-retardant nylon PA12 resin are shown in Table 1 below.

[0116] Table 1

[0117]

[0118] like Figure 4 As shown, the specific steps of the production process for the low-smoke halogen-free flame-retardant physically termite-proof aluminum-sheathed cable are as follows:

[0119] S1 cable core manufacturing: The cable core 1 is made by twisting together several core units 13. Each core unit 13 is made by twisting together several insulated single wires and then wrapping them with a layer of glass cloth tape. Preferably, in this embodiment, the cable core 1 is a four-core cable core, that is, the cable core 1 is made by twisting together four core units 13.

[0120] The glass cloth tape layer is made of inorganic glass fiber woven cloth tape wrapped around the surface. This structure can provide both tight binding and heat insulation.

[0121] Soft round copper wire conforming to the standard GB / T 3953-2024 Electrical Round Copper Wire is selected as conductor 11, with a nominal diameter of 1.0 mm. In specific manufacturing, four conductors 11 are selected, and different colored insulation layers 12 are coated on the four conductors 11 respectively. The insulation layer 12 is made of polyethylene insulation material (model CS K-3364NT CPD 3364), resulting in insulated single wires coated with red, green, white, and blue insulation layers 12 respectively. The nominal thickness of the insulation layer 12 is 0.6 mm, and the allowable deviation is ±0.1 mm.

[0122] S2 cable: The manufactured cables have two forming methods, one is twisted pair and the other is star stranded;

[0123] Wherein, the pair-twisted type is made of pair-twisted cable core units 13, each of which is made of two insulated single wires 13 of different colors in S1, which are twisted leftward as a whole and then wrapped with a layer of glass cloth tape (as shown in Figure 3 The twisted pitch is not greater than 300 mm; the pair-twisted color spectrum is: red / white, green / white, blue / green, blue / white;

[0124] The star-twisted type is made of star-shaped four-wire cable core units 13, each of which is made of four insulated single wires 13 of different colors in S1, which are twisted leftward as a whole and then wrapped with a layer of glass cloth tape (as shown in Figure 2 The twisted pitch is not greater than 300 mm; the star-shaped four-wire group with different twisted pitches should be loosely wound with different colors of non-hygroscopic silk; the star-shaped four-wire group A end line sequence arrangement should comply with the provisions of “TB / T2476-2017 Railway Signal Cable”;

[0125] Then, the four pair-twisted cable core units 13 or the four star-shaped four-wire cable core units 13 are twisted leftward to form a four-core cable core 1; the outer twisted direction of the cable core of other specifications is rightward, and the adjacent layers are twisted in opposite directions (the cable core is a comprehensive twisted structure, the pair-twisted group or the star-shaped four-wire group is first made, and then the pair-twisted group or the star-shaped four-wire group is twisted into a cable core;

[0126] Then, the cable core 1 is further wrapped with a non-woven fabric tape 2;

[0127] S3: PE insulation layer is made by extrusion coating on the non-woven fabric tape 2; the thickness of the PE insulation layer 3 should meet the requirements of the cable insulation performance to ground;

[0128] S4: aluminum sheath is made by coating on the PE insulation layer 3; the aluminum sheath 4 should be airtight and not leaky, and the aluminum sheath 4 should pass the bending test, the test method complying with the provisions of “GB / T 2951.23-1994 Wire and Cable Mechanical and Physical Property Test Methods Bending Test”;

[0129] S5: inner pad layer is made by extrusion coating on the aluminum sheath 4; the inner pad layer 5 uses low-smoke halogen-free flame-retardant oxygen barrier sheath material, and in addition, a polyethylene plastic sleeve can also be used;

[0130] S6: steel belt armor layer 6 is made by wrapping on the inner pad layer 5; the steel belt armor layer 6 is made of galvanized material, and in addition, the steel belt armor layer 6 can also be provided with two layers, and the steel belt armor layer 6 should comply with the provisions of “GB2952.2-1989 Cable Outer Sheath Metal Jacketed Cable General Outer Sheath”;

[0131] S7: manufacturing the inner layer outer sheath: the inner layer outer sheath 7 is manufactured outside the steel belt armor layer 6 by extrusion;

[0132] S8: manufacturing the outer layer outer sheath: the outer layer outer sheath 8 is manufactured outside the inner layer outer sheath 7 by extrusion;

[0133] Thus, the manufacturing of the cable is completed.

[0134] Performance tests are conducted on the low-smoke halogen-free flame-retardant physical termite-preventing aluminum sheath type cable prepared by the production process of Example 1. It can be concluded that the cable has excellent heat transfer blocking, combustible and oxygen blocking performance, and has physical termite prevention function, can reach the termite comprehensive control and termite prevention standard in the termite hazard area described in GB / T50768-2012 Termite Control Engineering, can improve the safety and reliability of railway signal line operation, and the physical termite prevention performance reaches the group evaluation and nest evaluation.

[0135] At the same time, the cable meets the requirements of flame retardation and electrical and physical properties, the flame retardation performance reaches the A-class flame retardation requirement, the physical termite prevention performance reaches the group evaluation and nest evaluation, and has excellent anti-aging performance. It still maintains good mechanical properties in the harsh UL oven for a long time, and has excellent mechanical properties and no discoloration after artificial climate aging test. Therefore, the low-smoke halogen-free flame-retardant physical termite-preventing aluminum sheath type cable can be widely applied to the signal system construction of various railways at home and abroad, has stable indicators and excellent performance, and has broad application prospects.

[0136] Example 2

[0137] Example 2 proposes a low-smoke halogen-free flame-retardant physical termite-preventing aluminum sheath type cable. The cable of Example 2 is different from that of Example 1 in that:

[0138] The inner pad layer 5 (low-smoke halogen-free oxygen barrier sheath material) is prepared from the following weight ratio of raw materials: ethylene-vinyl acetate copolymer EVA 10 parts, high-density polyethylene HDPE 30 parts, compatibilizer 10 parts, flame retardant I 90 parts, shell forming agent 7 parts, antioxidant 0.5 parts, lubricant 4 parts and coupling agent 3 parts.

[0139] The compatibilizer is maleic anhydride grafted styrene-ethylene-butadiene-styrene block copolymer (SEBS-g-MAH, where SEBS is linear and star-shaped, preferably linear SEBS, and the molecular weight is ≥70000). The grafting rate of maleic anhydride (MAH) is 0.5%-3%.

[0140] The flame retardant I is sodium tetraborate.

[0141] The antioxidant in the inner pad layer 5 is antioxidant BHT.

[0142] The lubricant in the inner pad layer 5 is calcium stearate.

[0143] The preparation method of the inner pad layer 5 comprises the following steps:

[0144] The raw materials of the inner pad layer 5 are mixed, then kneaded by a banbury mixer at a temperature of 190℃ for 14 minutes, and then extruded and granulated by a single screw extruder at a temperature of 130℃ and a rate of 248kg / hour.

[0145] The outer layer outer sheath is prepared from the following raw materials in parts by weight: 90 parts of flame-retardant nylon PA12 resin, 10 parts of plasticizer, 5 parts of char-forming agent, 2 parts of antioxidant, 2 parts of ultraviolet-resistant agent, 1 part of lubricant, and 30 parts of flame retardant II.

[0146] The flame retardant II is a phosphorus-nitrogen flame retardant, and its components include 21 parts of ADP (diethyl aluminum phosphinate), 7 parts of MPP (melamine polyphosphate), and 3.5 parts of zinc borate.

[0147] The plasticizer is tri-isononyl trimellitate.

[0148] The lubricant in the outer layer outer sheath 8 is calcium stearate.

[0149] Tests show that the low-smoke halogen-free flame-retardant physical termite-resistant aluminum sheath type cable produced by the production process of Example 2 can achieve the performance comparable to that of Example 1.

[0150] The above examples are illustrative of the embodiments of the present application, and the embodiments of the present application are not limited by the above examples. Any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement modes, and all shall be within the protection scope of the present application.

Claims

1. A low smoke, halogen-free, flame-retardant, physically termite resistant, aluminum sheathed cable, characterized in that, From inner layer to outer layer, the cable core, PE thermal insulation layer, aluminum sheath, inner pad layer, steel belt armored layer, inner outer sheath and outer outer sheath are arranged in sequence. The cable core is made of a plurality of cable core units in a twisted manner, and each cable core unit is made of a plurality of insulated single wires twisted and wrapped with a glass cloth tape layer. The glass cloth tape layer is made of inorganic glass fiber woven cloth tape. Each insulated single wire is made of a conductor and an insulating layer coated on the outer surface of the conductor, and the insulating layer has different colors. The flame-retardant nylon sheath material is used as the outer outer sheath.

2. The low smoke, halogen-free, flame retardant, physical termite resistant, aluminum sheathed cable of claim 1, wherein, The colors of the insulating layers are red, green, white and blue respectively, the nominal thickness of the insulating layer is 0.6 mm, and the allowable deviation is ±0.1 mm.

3. The low smoke, halogen-free, flame retardant, physical termite resistant, aluminum sheathed cable of claim 1 wherein, The twisting manner of the cable core unit is the opposite twisting type or the star twisting type. The cable core is made of four star type four-wire group cable core units in a left twisting manner, or the cable core is made of four opposite line group cable core units in a left twisting manner.

4. The low smoke, halogen-free, flame retardant, physical termite resistant, aluminum sheathed cable of claim 1 wherein, A non-woven fabric tape is further arranged between the PE thermal insulation layer and the cable core, and the non-woven fabric tape is arranged outside the cable core by wrapping; The PE thermal insulation layer is arranged outside the non-woven fabric tape by extrusion wrapping; The inner pad layer is arranged outside the aluminum sheath by extrusion wrapping.

Images