A low-smoke zero-halogen fire-resistant cable

Abstract

The invention relates to the technical field of cables, in particular to a low-smoke halogen-free fireproof cable, comprising an outer sheath; the outer sheath is made of the following raw materials in parts by weight: 40-60 parts of low-density polyethylene, 20-30 parts of EVA resin, 10-20 parts of SEBS elastomer, 5-10 parts of POE-g-GMA, 5-10 parts of flame retardant, 15-30 parts of filler and 1-5 parts of auxiliary agent; the flame retardant consists of an organic component and a spinel metal oxide; the organic component comprises a DOPO derivative and a nitrogen-based flame retardant. The outer sheath granules prepared by the invention have excellent mechanical properties and excellent fire-retardant properties, not only have a high flame retardant grade, but also generate little heat and smoke after combustion, and are excellent materials for preparing low-smoke halogen-free fireproof cables.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and specifically to a low-smoke and halogen-free fire-resistant cable. Background Art

[0002] With the rapid development of the economic society, the application and demand of cables in various fields are increasing continuously. When the cable sheath containing halogen flame retardant burns, it will generate a large amount of thick smoke and harmful gases, thereby increasing the risk of fire rescue. Therefore, halogen-free, low-smoke and flame-retardant wires and cables have become an important research direction.

[0003] At present, the mainstream low-smoke and halogen-free cables are based on polyolefin, and inorganic flame retardants or organic flame retardants are added to achieve flame retardancy. Inorganic flame retardants have defects such as low flame retardancy efficiency, significant decline in material mechanical properties such as tensile strength and flexibility due to high addition amount, difficult processing, and inability to form a stable carbon layer to inhibit combustion. While organic flame retardants such as DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) have problems such as poor thermal stability and easy decomposition during processing. Therefore, how to achieve the synergy of multiple flame retardants through compounding, while improving the fire resistance of the cable and still having good mechanical properties has become an urgent problem to be solved at present. Summary of the Invention

[0004] Object of the Invention: Aiming at the above technical problems, the present invention provides a low-smoke and halogen-free fire-resistant cable.

[0005] The technical solution adopted is as follows:

[0006] A low-smoke and halogen-free fire-resistant cable includes an outer sheath;

[0007] By weight, the outer sheath is made of the following raw materials in parts by weight:

[0008] 40-60 parts of low-density polyethylene, 20-30 parts of EVA resin, 10-20 parts of SEBS elastomer, 5-10 parts of POE-g-GMA, 5-10 parts of flame retardant, 15-30 parts of filler, 1-5 parts of auxiliary agent;

[0009] The flame retardant is composed of an organic component and a spinel-type metal oxide;

[0010] The organic component includes a DOPO derivative and a nitrogen-based flame retardant;

[0011] The structural formula of the DOPO derivative is shown as the following formula (1):

[0012] ;

[0013] Wherein, R 1 、R 2 、R3 and R 4 are each independently hydrogen or a structure represented by formula (2), and R 1 and R 2 and R 3 and R 4 are not simultaneously hydrogen. In formula (2), is the connection site with the oxygen atom in formula (1).

[0014] .

[0015] Furthermore, the structural formula of the DOPO derivative is as follows:

[0016] .

[0017] Furthermore, the preparation method of the DOPO derivative is as follows:

[0018] Pentaerythritol reacts with 4-maleimidobenzoic acid to obtain an intermediate, and the intermediate is then added with DOPO to obtain the DOPO derivative.

[0019] Furthermore, the spinel-type metal oxide is ZnFe 2 O 4 .

[0020] Furthermore, the mass ratio of the organic component to the spinel-type metal oxide is 1:0.1 - 1.

[0021] More preferably, the mass ratio of the organic component to the spinel-type metal oxide is 1:0.25.

[0022] Furthermore, the mass ratio of the DOPO derivative to the nitrogen-based flame retardant is 1 - 10:1 - 10.

[0023] More preferably, the mass ratio of the DOPO derivative to the nitrogen-based flame retardant is 1:1.

[0024] Furthermore, the nitrogen-based flame retardant is at least one of melamine, melamine cyanurate, and melamine polyphosphate, and preferably melamine cyanurate.

[0025] Furthermore, the filler is composed of montmorillonite and carbon black with a mass ratio of 1 - 5:1 - 5.

[0026] More preferably, the filler is composed of montmorillonite and carbon black with a mass ratio of 1:1.

[0027] Furthermore, the additives include a lubricant and an antioxidant.

[0028] More preferably, the lubricant is PE wax and / or oxidized PE wax.

[0029] Further, it also includes a cable core composed of a conductor and a cross-linked polyethylene inner sheath;

[0030] The outer side of the cable core is sequentially coated with an aluminum-plastic composite tape, a mica wrapping tape, and the outer sheath.

[0031] It has the following beneficial effects:

[0032] The present invention provides a low-smoke and halogen-free fire-resistant cable. The outer sheath can not only protect the conductors and other structural components inside the cable from the influence of the external environment, such as mechanical damage, chemical corrosion, moisture erosion, etc., ensure the stability and reliability of the cable during long-term operation, extend the service life of the cable, but also does not contain halogens, produces less smoke and heat when encountering fire, and can effectively prevent the spread of fire, winning precious time for personnel evacuation and fire fighting and rescue;

[0033] The raw material formula of the outer sheath of the present invention is a carefully formulated system, and each raw material performs its own functions, jointly endowing the outer sheath with excellent comprehensive performance. Among them, low-density polyethylene is used as the basic raw material, providing the outer sheath with basic flexibility and good processing performance, making the outer sheath easy to form.

[0034] The presence of vinyl acetate monomers in the EVA resin molecular structure weakens the crystallization effect between polyethylene chain segments, enhancing the mobility of molecular chains. This characteristic effectively improves the flexibility of the outer sheath, making it softer and easier to bend while maintaining a certain strength.

[0035] SEBS elastomer belongs to styrene-based thermoplastic elastomers, and its microstructure is composed of polystyrene hard segments and polybutadiene soft segments. This special structure makes SEBS exhibit high rubber-like elasticity at room temperature, endowing the outer sheath with excellent tensile and compression properties. In actual use, the outer sheath can withstand large external force deformations without permanent damage and quickly return to its original state after being stressed, effectively improving the anti-deformation ability and durability of the product.

[0036] As a compatibilizer, POE-g-GMA contains polar groups and non-polar groups in its molecular structure, thus forming a bridge between different polymers, reducing the interfacial tension, enabling them to disperse and mix better, improving the compatibility of the entire system, and ensuring the uniformity and stability of the outer sheath material. It can also chemically react or physically entangle with other polymers to form a network-like structure. This structure enhances the interaction force between polymers and improves mechanical indexes such as the tensile strength, tear strength, and impact resistance of the outer sheath.

[0037] The DOPO molecule contains phosphorus in its molecular structure. At high temperatures, a series of chemical reactions occur to the phosphorus element. When exposed to a fire source, DOPO decomposes to generate phosphorus-containing free radicals. These free radicals can react with the highly reactive free radicals produced during the combustion of polymers, capture them, and convert them into relatively stable substances, thereby interrupting the free radical chain transfer of the combustion reaction and inhibiting the continuous progress of combustion. The DOPO derivative in the flame retardant of the present invention introduces a hydroxyl group and a benzene ring structure compared to DOPO. The benzene ring can provide a rigid skeleton to increase thermal stability and will not decompose during processing. The hydroxyl group optimizes the flame retardant mechanism through chemical bonding and charring. The two work together to significantly enhance its flame retardant performance by enhancing the thermal stability and charring efficiency of DOPO, enabling the DOPO derivative to achieve an efficient, long-lasting, and environmentally friendly flame retardant effect in the cable outer sheath.

[0038] Nitrogen-based flame retardants exert their flame retardant effects based on the synergistic effect of gas-phase flame retardancy and condensed-phase flame retardancy. In the gas phase, nitrogen-based flame retardants decompose when heated to produce non-combustible gases such as ammonia and nitrogen, diluting the concentration of combustible gases and inhibiting the progress of the combustion reaction. In the condensed phase, nitrogen-based flame retardants decompose to form a dense carbonaceous layer, which can isolate oxygen and heat and prevent the further spread of combustion. Nitrogen-based flame retardants and DOPO derivatives can achieve efficient flame retardancy through multiple paths such as gas-phase free radical inhibition, condensed-phase carbon layer strengthening, and acid source-gas source complementarity.

[0039] Spinel-type metal oxides have a unique spinel structure, which endows them with special physical and chemical properties. When acting synergistically with DOPO derivatives, spinel-type metal oxides can promote the more effective capture of combustion free radicals by the phosphorus-containing free radicals generated by the decomposition of DOPO derivatives, enhance the ability to inhibit the combustion chain reaction, and further reduce the combustion rate. Spinel-type metal oxides can participate in the formation process of the carbonaceous layer at high temperatures. It can make the carbonaceous layer more dense and stable, enhance its heat insulation and oxygen isolation performance, so as to better block the transfer of oxygen and heat, and provide more effective protection for the outer sheath during combustion. In addition, spinel-type metal oxides themselves can also undergo some physical and chemical changes at high temperatures, absorb part of the heat, and assist in reducing the temperature of the outer sheath, jointly constructing a multi-level and all-round flame retardant system with other flame retardants, significantly enhancing the overall flame retardant effect of the outer sheath and improving its safety in a fire. Description of the Drawings

[0040] Figure 1 It is a schematic structural diagram of a low-smoke and halogen-free fire-resistant cable in Example 1. The labels in the figure represent respectively:

[0041] 1 - Copper conductor, 2 - Cross-linked polyethylene inner sheath, 3 - Aluminum-plastic composite tape, 4 - Mica tape wrapping, 5 - Outer sheath. Detailed Embodiments

[0042] For those without specific conditions indicated in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments without the manufacturer indicated, they are all conventional products that can be obtained through commercial purchase. Technologies not mentioned in the present invention refer to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel tests and adopt the same processing steps and parameters.

[0043] Low-density polyethylene: PE1018, ExxonMobil;

[0044] EVA resin: 2315, Hanwha Korea;

[0045] SEBS elastomer: G1650MU, Kraton USA;

[0046] POE-g-GMA: SH035, Dongguan Shenghao Plastic Raw Materials Co., Ltd.;

[0047] DOPO derivative: self-made;

[0048] Melamine cyanurate: FR-MCA, Dongguan Xingyuan Chemical Co., Ltd.;

[0049] ZnFe 2 O 4 : Zhongke Jinyan (Beijing) Technology Co., Ltd.;

[0050] Montmorillonite: Hebei Hengyue Mineral Products Co., Ltd.;

[0051] Carbon black N330: Shandong Kasong New Materials Co., Ltd.;

[0052] PE wax: JRF-200, Shanghai Jinhu Rili Plastics Co., Ltd.;

[0053] Antioxidant 1010: JY-1010, Beijing Jiyi New Materials.

[0054] Example 1:

[0055] A low-smoke and halogen-free fire-resistant cable includes a cable core composed of a copper conductor 1 and a cross-linked polyethylene inner sheath 2;

[0056] Outside the cable core, an aluminum-plastic composite tape 3, a mica wrapping tape 4, and an outer sheath 5 are sequentially coated;

[0057] By weight, the outer sheath 5 is made of the following raw materials in parts by weight:

[0058] 50 parts of low-density polyethylene, 25 parts of EVA resin, 15 parts of SEBS elastomer, 8 parts of POE-g-GMA, 10 parts of flame retardant, 10 parts of montmorillonite, 10 parts of carbon black N330, 1 part of PE wax, 1 part of antioxidant 1010;

[0059] The flame retardant consists of 4 parts of DOPO derivative, 4 parts of melamine cyanurate and 2 parts of ZnFe 2 O 4 2;

[0060] The structural formula of the DOPO derivative is as follows:

[0061] .

[0062] The preparation method of the DOPO derivative is as follows:

[0063] ;

[0064] S1: In a dry reaction flask, dissolve 4-maleimidobenzoic acid (such as 20 mmol) in anhydrous DMF (200 ml), cool it to 0 - 5 °C in an ice bath, slowly add DCC (22 mmol), then add DMAP (0.5 mmol), stir for 30 min, add pentaerythritol (10 mmol) to the solution, remove the ice bath, raise the temperature to 40 °C and stir for 12 h. After the reaction, restore to room temperature and filter. Concentrate the filtrate with a rotary evaporator, dissolve the residue in ethyl acetate (300 mL), wash it successively with 5% dilute hydrochloric acid, saturated sodium bicarbonate solution, and deionized water, and finally dry it with anhydrous sodium sulfate and concentrate it under reduced pressure to obtain the intermediate.

[0065] ;

[0066] Add the intermediate (5 mmol) and DOPO (10 mmol) to 200 ml of methanol, stir and raise the temperature to 55 °C for reaction for 10 h. After the reaction, distill off methanol under reduced pressure, and recrystallize with 20 ml of dichloromethane and 100 ml of ethyl acetate to obtain the DOPO derivative with a yield of 50.3%. ESI-MS(m / z)(M + ): Theoretical value 966.83, measured value 966.46.

[0067] The preparation method of the outer sheath pellets is as follows:

[0068] Place the raw materials in a high-speed mixer, mix at 80 °C for 10 min, then transfer to a twin-screw extruder. The length-diameter ratio of the twin-screw extruder is 40:1, the screw speed is 200 - 300 rpm, the temperature of zone 1 is 120 - 140 °C, the temperature of zone 2 is 150 - 160 °C, the temperature of zone 3 is 160 - 170 °C, the temperature of zone 4 is 170 - 180 °C, and the die head temperature is 175 - 185 °C. The extruded strip is cooled by a water-cooling tank and then pelletized to obtain the outer sheath pellets.

[0069] Example 2:

[0070] A low-smoke and halogen-free fire-resistant cable, comprising a cable core composed of a conductor 1 and an inner sheath 2;

[0071] The outside of the cable core is successively coated with an aluminum-plastic composite tape 3, a mica tape 4 and an outer sheath 5;

[0072] By weight, the outer sheath 5 is made of the following raw materials in parts by weight:

[0073] 60 parts of low-density polyethylene, 30 parts of EVA resin, 20 parts of SEBS elastomer, 10 parts of POE-g-GMA, 10 parts of flame retardant, 10 parts of montmorillonite, 10 parts of carbon black N330, 1 part of PE wax, 1 part of antioxidant 1010;

[0074] The flame retardant consists of 4 parts of DOPO derivative, 4 parts of melamine cyanurate and 2 parts of ZnFe 2 O 4 2;

[0075] The structural formula and preparation method of the DOPO derivative are the same as those in Example 1.

[0076] The preparation method of the outer sheath pellets is as follows:

[0077] Place the raw materials in a high-speed mixer, mix at 80 °C for 10 min and then transfer to a twin-screw extruder. The length-diameter ratio of the twin-screw extruder is 40:1, the screw speed is 200 - 300 rpm, the temperature of the first zone is 120 - 140 °C, the temperature of the second zone is 150 - 160 °C, the temperature of the third zone is 160 - 170 °C, the temperature of the fourth zone is 170 - 180 °C, the temperature of the die head is 175 - 185 °C. The extruded strip is cooled by a water-cooling tank and then pelletized to obtain the outer sheath pellets.

[0078] Example 3:

[0079] A low-smoke and halogen-free fire-resistant cable, comprising a cable core composed of a conductor 1 and an inner sheath 2;

[0080] The outside of the cable core is successively coated with an aluminum-plastic composite tape 3, a mica tape 4 and an outer sheath 5;

[0081] By weight, the outer sheath 5 is made of the following raw materials in parts by weight:

[0082] 40 parts of low-density polyethylene, 30 parts of EVA resin, 10 parts of SEBS elastomer, 5 parts of POE-g-GMA, 10 parts of flame retardant, 10 parts of montmorillonite, 10 parts of carbon black N330, 1 part of PE wax, 1 part of antioxidant 1010;

[0083] The flame retardant consists of 4 parts of DOPO derivative, 4 parts of melamine cyanurate and 2 parts of ZnFe 2 O 4 2;

[0084] The structural formula and preparation method of the DOPO derivative are the same as those in Example 1.

[0085] The preparation method of the outer sheath granule is as follows:

[0086] Place the raw materials in a high-speed mixer, mix at 80 °C for 10 min, and then transfer them to a twin-screw extruder. The length-diameter ratio of the twin-screw extruder is 40:1, the screw rotation speed is 200 - 300 rpm, the temperature of the first zone is 120 - 140 °C, the temperature of the second zone is 150 - 160 °C, the temperature of the third zone is 160 - 170 °C, the temperature of the fourth zone is 170 - 180 °C, and the temperature of the die head is 175 - 185 °C. The extruded strip is cooled by a water-cooling tank and then pelletized to obtain the outer sheath granule.

[0087] Comparative Example 1:

[0088] It is basically the same as Example 1, except that the SEBS elastomer is not added to the raw materials of the outer sheath 5.

[0089] Comparative Example 2:

[0090] It is basically the same as Example 1, except that the POE-g-GMA is not added to the raw materials of the outer sheath 5.

[0091] Comparative Example 3:

[0092] It is basically the same as Example 1, except that the DOPO derivative is not contained in the flame retardant.

[0093] Comparative Example 4:

[0094] It is basically the same as Example 1, except that DOPO is used to replace the DOPO derivative in the flame retardant.

[0095] Comparative Example 5:

[0096] It is basically the same as Example 1, except that the melamine cyanurate is not contained in the flame retardant.

[0097] Comparative Example 6:

[0098] It is basically the same as Example 1, except that the ZnFe 2 O 4 .

[0099] Comparative Example 7:

[0100] It is basically the same as Example 1, except that ZnO is used to replace the ZnFe 2 O 4 .

[0101] Performance Test

[0102] The outer sheath pellets in Examples 1-3 and Comparative Examples 1-7 of the present invention were made into specimens for performance testing.

[0103] The tensile strength was tested according to the provisions of GB / T 1040.3-2006 "Determination of Tensile Properties of Plastics - Part 3: Test Conditions for Films and Sheets". The specimen was of Type 5, and the tensile rate was 100 mm / min.

[0104] Limiting oxygen index (LOI) test: It was tested on an oxygen index meter according to the ASTM D2863-77 standard. The size of the specimen was 100 mm × 6.5 mm × 3 mm.

[0105] According to the GB / T 2408-2008 test standard, a vertical burning test instrument (ZY6017) was used to measure the UL-94 vertical burning level. The size of the specimen was 130 mm × 13 mm × 3 mm.

[0106] The ISO5660-1 standard was adopted to test the changes of heat release and smoke release with time during the combustion of the specimen. The radiation power was 50 kW. The size of the specimen was 100 mm × 100 mm × 3 mm, and the total heat release (THR) and total smoke release (TSR) were determined.

[0107] The test results are shown in Table 1 below:

[0108] Table 1:

[0109]

[0110] As can be seen from Table 1 above, the outer sheath pellets prepared by the present invention have excellent mechanical properties and excellent fireproof and flame-retardant properties. Not only is the flame-retardant grade high, but also the heat and smoke generated after combustion are small. It is an excellent material for preparing low-smoke and halogen-free fireproof cables.

[0111] Comparing Example 1 with Comparative Examples 1-2, it can be seen that the addition of SEBS elastomer and POE-g-GMA has played a positive role in improving the mechanical properties of the outer sheath;

[0112] Comparing Example 1 with Comparative Examples 3 and 5, it can be seen that the addition of DOPO derivatives, melamine cyanurate and ZnFe 2 O 4 has played a positive role in improving the fireproof and flame-retardant properties of the outer sheath;

[0113] Comparing Example 1 with Comparative Example 4, it can be seen that, compared with DOPO, the addition of DOPO derivatives has a greater improvement in the fireproof and flame-retardant properties of the outer sheath.

[0114] Comparing Example 1 with Comparative Example 6, it can be seen that, compared with ZnO, ZnFe 2 O4 The addition has a greater improvement in the fireproof and flame-retardant performance of the outer sheath.

[0115] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low smoke halogen-free fireproof cable, characterized in that: Including outer sheath; The outer sheath is made of the following raw materials in parts by weight: 40-60 parts of low-density polyethylene, 20-30 parts of EVA resin, 10-20 parts of SEBS elastomer, 5-10 parts of POE-g-GMA, 5-10 parts of flame retardant, 15-30 parts of filler, 1-5 parts of additives; The flame retardant is composed of an organic component and a spinel metal oxide; The organic component includes a DOPO derivative and a nitrogen-based flame retardant; The structural formula of the DOPO derivative is shown in the following formula (1): Formula (1); Wherein, R1, R2, R3, and R4 are independently hydrogen or a structure shown in formula (2) and R1, R2, R3, and R4 are not hydrogen at the same time, and the * in formula (2) is the connection site with the oxygen atom in formula (1) Formula (2); The spinel metal oxide is ZnFe2O4.

2. The low smoke zero halogen fireproof cable according to claim 1, characterized in that: The structural formula of the DOPO derivative is shown below: 。 3. The low smoke zero halogen fireproof cable according to claim 2, characterized in that: The preparation method of the DOPO derivative is as follows: Pentaerythritol reacts with 4-maleimidobenzoic acid to obtain an intermediate, and the intermediate is then added with DOPO to obtain the DOPO derivative.

4. The low smoke zero halogen fireproof cable according to claim 1, characterized in that: The mass ratio of the organic component to the spinel metal oxide is 1:0.1-1.

5. The low smoke zero halogen fireproof cable according to claim 1, characterized in that: The mass ratio of the DOPO derivative to the nitrogen-based flame retardant is 1-10:1-10.

6. The low smoke zero halogen fireproof cable according to claim 1, characterized in that: The nitrogen-based flame retardant is at least one of melamine, melamine cyanurate and melamine polyphosphate.

7. The low smoke zero halogen fireproof cable according to claim 1, characterized in that: The filler consists of montmorillonite and carbon black in a mass ratio of 1-5:1-5.

8. The low smoke zero halogen fireproof cable according to claim 1, characterized in that: The auxiliary agents include lubricants and antioxidants.

9. The low smoke zero halogen fire resistant cable according to any one of claims 1 to 8, characterized in that: Also included is a cable core consisting of a conductor and a cross-linked polyethylene inner sheath; The outer side of the cable core is sequentially coated with an aluminum-plastic composite wrapping tape, a mica wrapping tape and the outer sheath.

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