High-toughness flame-retardant silicone rubber / nylon composite elastomer material and method for producing the same

Abstract

The application discloses a high-toughness flame-retardant silicone rubber / nylon composite elastomer material and a preparation method thereof, and solves the technical problem of poor mechanical properties of traditional thermosetting silicone rubber and the risk of cracking in the use of the traditional thermosetting silicone rubber in electric wires and cables. The material is composed of silicone rubber mixing rubber, nylon elastomer, N-P compound flame retardant, bio-based fatty acid ester plasticizer, flame-retardant synergist, phase structure regulator and other raw materials. Through optimization of the formula design, the defects of long processing flow and non-recyclable of the traditional thermosetting silicone rubber are overcome, the prepared composite elastomer material reaches V-0 level in UL94 vertical burning performance, and has excellent mechanical properties, flame-retardant properties, processing performance and oil resistance. The material can be widely applied to the technical field of thermoplastic elastomer materials.

Description

Technical Field

[0001] This invention relates to the field of thermoplastic elastomer materials technology, specifically to a high-toughness flame-retardant silicone rubber / nylon composite elastomer material and its preparation method. Background Technology

[0002] In the wire and cable industry, the performance of the outer sheath material directly determines the product's safety, reliability, and environmental adaptability. Traditional silicone rubber, as the mainstream material, possesses excellent resistance to high and low temperatures, electrical insulation, and physiological inertness. However, traditional silicone wires use thermosetting silicone rubber, whose curing process is an irreversible chemical cross-linking reaction. This results in lengthy processing steps, high energy consumption, and the inability to recycle scraps due to the irreversible cross-linking network. Furthermore, silicone rubber has inherent mechanical defects, with low tear strength, making it prone to sheath cracking under frequent bending and friction, especially in dynamic service environments such as high-voltage cables for new energy vehicles and high-speed data transmission cables, significantly increasing reliability risks.

[0003] Thermoplastic elastomers, through their unique segmental structure, can effectively improve the toughness of materials. When blended with silicone rubber, they are expected to improve the shortcomings of silicone rubber's mechanical properties. However, the blending of thermoplastic elastomers and silicone rubber currently has the following problems: (1) When polar elastomers are directly blended with non-polar silicone rubber, macroscopic phase separation is easily formed, leading to a decrease in mechanical properties. (2) It is difficult for a single flame retardant to simultaneously meet the UL94 V-0 flame retardant rating and low hardness requirements at low addition levels. (3) Traditional plasticizers (such as phthalates) are prone to migration, leading to a rebound in hardness during long-term use.

[0004] Chinese patent CN106751736A discloses a silicone rubber / polyurethane thermoplastic elastomer and its preparation method. It uses polyurethane thermoplastic elastomer (TPU) and silicone rubber to prepare an elastomer, which has good heat resistance, friction resistance and mechanical properties. However, according to its performance test results, its flame retardant properties and mechanical properties cannot meet the requirements of high-quality cable products. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a high-toughness flame-retardant silicone rubber / nylon composite elastomer material and its preparation method. The present invention overcomes the shortcomings of the traditional thermosetting silicone rubber processing flow being lengthy and the scrap material being non-recyclable. The prepared composite elastomer material achieves a UL94 vertical flammability rating of V-0 and possesses excellent mechanical properties, flame retardant properties, processing properties, and oil resistance.

[0006] To achieve the above objectives, in a first aspect, embodiments of the present invention provide a high-toughness flame-retardant silicone rubber / nylon composite elastomer material, composed of the following raw materials in parts by weight:

[0007] The composition includes: 100 parts silicone rubber compound, 80-155 parts nylon elastomer, 55-85 parts NP compound flame retardant, 15-30 parts bio-based fatty acid ester plasticizer, 7-20 parts flame retardant synergist, 7-20 parts phase structure modifier, 5-10 parts nano montmorillonite, 1-3 parts crosslinking agent, 0.5-1 part initiator, 0.2-0.5 parts antioxidant, 0.8-1.6 parts UV stabilizer, and 0.2-0.5 parts lubricant.

[0008] The silicone rubber compound is a methyl vinyl silicone rubber with a Shore hardness of 20A-40A and a vinyl content of 0.1%.

[0009] The nylon elastomer is composed of 70-130 parts of TPAE-based polyamide copolymer and 10-25 parts of MBPA multiblock polyamide copolymer, wherein the Shore hardness of the TPAE-based polyamide copolymer and the MBPA multiblock polyamide copolymer is 25D-35D.

[0010] The phase structure modifier comprises 5-15 parts of ethylene-α-olefin copolymer-g-MAH and 2-5 parts of aminosilane coupling agent.

[0011] In the embodiments of the present invention, the molecular weight of the methyl vinyl silicone rubber is about 400,000, and the silicone rubber compound can be selected from Wacker Chemie, Shin-Etsu Chemical KE-103, or Dow Corning SYLGARD184.

[0012] Preferably, the hard segment of the TPAE-based polyamide copolymer and the soft segment of the MBPA multiblock polyamide copolymer are PA12 and PTMG, the number of blocks in the TPAE-based polyamide copolymer is 2, and the number of blocks in the MBPA multiblock polyamide copolymer is ≥12.

[0013] In embodiments of the present invention, the TPAE-based polyamide copolymer serves as the base component of the nylon elastomer, ensuring the material's basic mechanical properties and processing fluidity. TPAE-based polyamide copolymers can be selected from Evonik Degussa Pebax® 1657, Arkema PEBAX MV1074, and DuPont Zytel® PEBA 3533. The MBPA multi-block polyamide copolymer, through its ≥12-segment multi-block structure, disperses stress concentration, further enhancing the material's toughness and fatigue resistance. MBPA multi-block polyamide copolymers can be selected from Evonik Degussa Pebax® 1657, Arkema PEBAX RV3056, and Toray PEBASOL 5533.

[0014] Preferably, the NP compound flame retardant is a mixture of piperazine pyrophosphate and melamine polyphosphate in a mass ratio of 2:1; the flame retardant synergist is polyketide resin.

[0015] In embodiments of the present invention, piperazine pyrophosphate releases polyphosphoric acid during combustion to promote char layer formation. Piperazine pyrophosphate can be selected from Jiangsu Yake Technology YAK-APP, Aike Reagent AKnoka® NP820, and Shouguang Weidong Chemical WD-PP. Melamine polyphosphate releases non-flammable gas to dilute oxygen and assist in the expansion of the char layer. Melamine polyphosphate can be selected from Zhejiang Wansheng Co., Ltd. WS-MPP, Guangzhou Jushi Chemical JSP-MPP, and Jiangsu Yake Technology YAK-MPP. Polyketone resin acts as a flame retardant synergist, enhancing the crosslinking density and heat resistance of the char layer and inhibiting dripping and heat transfer. It can be selected from Korean Hyosung POK M330A and Korean Hyosung POK M23AG3A.

[0016] Preferably, the bio-based fatty acid ester plasticizer is at least one of castor oil-based fatty acid methyl ester, soybean oil-based fatty acid methyl ester, and palm oil-based fatty acid ethyl ester.

[0017] Preferably, the ethylene-α-olefin copolymer-g-MAH is an ethylene-octene copolymer-g-MAH with a grafting rate of 1.5%-2.0%.

[0018] In embodiments of the present invention, the ethylene-octene copolymer-g-MAH forms hydrogen bonds with the polar groups of the nylon elastomer through maleic anhydride groups, and the ethylene segments are entangled with the silicone rubber, improving the interfacial compatibility between the two phases. The ethylene-octene copolymer-g-MAH can be selected from Dow Chemical Engage G-1900, DuPont Elvaloy PTW, and Mitsui Chemicals TAFMER A3000. The aminosilane coupling agent strengthens the interfacial bonding by forming chemical covalent bonds through the reaction of amino groups with nylon and the condensation of siloxane groups with silicone rubber. The aminosilane coupling agent can be selected from Dow Corning Z-6011, Momentive A-1100, and Shin-Etsu KBM-603.

[0019] Preferably, the crosslinking agent includes at least one of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane or tert-butyl peroxyisopropyl carbonate.

[0020] Preferably, the initiator is tert-butyl peroxyisopropyl carbonate or benzoyl peroxide.

[0021] Preferably, the antioxidant is a 1:1 mixture of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl)phosphite;

[0022] The UV-resistant agent is at least one of benzotriazole UV234 or benzophenone UV531.

[0023] Based on the requirement of high-toughness cable sheathing, the basic system of this invention uses methyl vinyl silicone rubber with a Shore hardness of 20A-40A as the flexible matrix and a compound nylon elastomer with a Shore hardness of 25D-35D as the rigid phase. The silicone rubber and nylon elastomer form an interpenetrating network structure through molecular chain entanglement and interfacial interaction, avoiding phase separation and allowing stress to be uniformly transmitted between the two phases, reducing crack propagation. This synergistically improves the tensile strength, elongation at break, and tear strength of the material, and the prepared composite elastomer material has excellent mechanical properties.

[0024] In this invention, the 2-block TPAE structure of the nylon elastomer possesses a low glass transition temperature, providing fundamental mechanical properties and ensuring basic tensile strength and processing fluidity. The dense distribution of hard segments in the multi-block MBPA structure disperses stress concentration, further enhancing the material's ductility and preventing embrittlement. Insufficient MBPA segments would negatively impact the material's mechanical properties. This combination allows the nylon elastomer to form a uniformly dispersed "hard core-soft shell" structure within the silicone rubber matrix, significantly improving the composite system's toughness and fatigue resistance. A moderate hardness (25D-35D) balances rigidity and elasticity, enabling the nylon elastomer to act as a reinforcing phase to enhance the strength of silicone rubber without compromising its flexibility. If the hardness is too low, the hard segment microregions cannot form effective physical cross-linking points; if it is too high, the soft segment fluidity will decrease, weakening the molecular entanglement with the silicone rubber.

[0025] To address the phase separation problem between polar nylon and non-polar silicone rubber, this invention improves interfacial tension through a bidirectional compatibility combination of ethylene-α-olefin copolymer-g-MAH and aminosilane coupling agent. Neither ethylene-α-olefin copolymer-g-MAH nor aminosilane coupling agent alone is ideal for improving the mechanical properties of composite elastomer materials.

[0026] To enhance flame retardant performance, this invention employs a specific ratio of NP-based compound flame retardants. When compounded at a 2:1 ratio, nitrogen and phosphorus elements form a dual flame retardant mechanism of "gas-phase dilution + condensed-phase char layer," resulting in a denser char layer and higher flame retardant efficiency than single-component applications. The flame retardant synergist, polyketone resin, promotes char layer cross-linking, improves char layer strength and heat resistance, and prevents dripping and heat transfer. It synergistically enhances the flame retardant rating with the NP system, reducing the effective amount of flame retardant required. The introduction of nano-montmorillonite further enhances the dispersibility of the flame retardant in the matrix. Simultaneously, the layered structure of montmorillonite inhibits dripping and smoke diffusion during combustion, synergistically improving flame retardant performance.

[0027] The present invention uses bio-based fatty acid ester plasticizers, which have better compatibility with silicone rubber and nylon elastomers. They can be stably inserted between molecular chains, reducing the intermolecular forces and making them less prone to migration, thereby improving the flexibility and processing fluidity of the material. At the same time, the bio-based components are environmentally friendly.

[0028] Secondly, the present invention provides a method for preparing the above-mentioned composite elastomer material, comprising the following steps:

[0029] (1) Premixing stage: Add silicone rubber compound, nylon elastomer, NP compound flame retardant, bio-based plasticizer, flame retardant synergist, phase structure modifier and nano montmorillonite to a high-speed mixer and mix for 30 min to 40 min at 80℃-100℃ and 300 rpm-500 rpm.

[0030] (2) One-time extrusion: The premixed material from step (1) is fed into a twin-screw extruder and melt-blended at 180℃-220℃ and screw speed of 200rpm-300rpm. After extrusion through the die, it is water-cooled and granulated to obtain prepolymer granules.

[0031] (3) Secondary mixing: The prepolymer granules are added to an internal mixer with initiator, crosslinking agent, antioxidant, UV stabilizer and lubricant. The mixture is mixed at 100℃-120℃ and rotor speed of 50rpm-80rpm for 15min-20min, and then extruded and granulated again by a single screw extruder.

[0032] Thirdly, the present invention provides the application of the above-mentioned composite elastomer material in the outer sheath of wires and cables.

[0033] Furthermore, the preparation process of the outer sheath of the wire and cable is as follows: the composite elastomer material is coated onto the outer layer of the conductor through an extruder, and after cooling, an outer sheath layer with a thickness of 0.5mm-1.5mm is formed.

[0034] The present invention has the following beneficial effects:

[0035] This invention provides a high-toughness flame-retardant silicone rubber / nylon composite elastomer material. Through the synergistic effect of silicone rubber compound and a specific ratio of nylon elastomer, the toughness is significantly improved, overcoming the low tear strength defect of traditional silicone rubber. The use of NP-compounded flame retardant and polyketone resin achieves a UL94V-0 flame retardant rating with low addition levels, solving the problem of single flame retardants failing to simultaneously achieve flame retardancy and low hardness. A two-way compatibilizer system effectively improves the compatibility of polar and non-polar components, avoiding the decline in mechanical properties caused by phase separation. Bio-based fatty acid ester plasticizers replace traditional plasticizers, reducing migration and resulting in minimal hardness changes over long-term use. Furthermore, the material is a thermoplastic system, simplifying the processing flow, reducing energy consumption, and allowing for the recycling of scraps, overcoming the processing and recycling difficulties of traditional thermosetting silicone rubber. In addition, the material also possesses excellent oil resistance, aging resistance, and processing fluidity, making it suitable for high-quality wire and cable sheathing applications. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] While traditional silicone rubber, as the mainstream material, possesses excellent resistance to high and low temperatures, electrical insulation, and physiological inertness, traditional silicone wires use thermosetting silicone rubber. The curing process of this type of material is an irreversible chemical cross-linking reaction, resulting in lengthy processing steps, high energy consumption, and the inability to recycle scraps due to the irreversible cross-linking network. Furthermore, silicone rubber itself has inherent mechanical defects. Currently, the tensile strength of silicone rubber materials is mostly between 6-10 MPa, making them prone to surface cracking under frequent bending and friction in cable applications. This significantly increases reliability risks, especially in dynamic service environments such as high-voltage cables for new energy vehicles and high-speed data transmission cables.

[0038] This invention provides a high-toughness flame-retardant silicone rubber / nylon composite elastomer material, composed of the following raw materials in parts by weight:

[0039] The composition includes: 100 parts silicone rubber compound, 80-155 parts nylon elastomer, 55-85 parts NP compound flame retardant, 15-30 parts bio-based fatty acid ester plasticizer, 7-20 parts flame retardant synergist, 7-20 parts phase structure modifier, 5-10 parts nano montmorillonite, 1-3 parts crosslinking agent, 0.5-1 part initiator, 0.2-0.5 parts antioxidant, 0.8-1.6 parts UV stabilizer, and 0.2-0.5 parts lubricant.

[0040] The silicone rubber compound is a methyl vinyl silicone rubber with a Shore hardness of 20A-40A and a vinyl content of 0.1%.

[0041] The nylon elastomer is composed of 70-130 parts of TPAE-based polyamide copolymer and 10-25 parts of MBPA multiblock polyamide copolymer, wherein the Shore hardness of the TPAE-based polyamide copolymer and the MBPA multiblock polyamide copolymer is 25D-35D.

[0042] The phase structure modifier comprises 5-15 parts of ethylene-α-olefin copolymer-g-MAH and 2-5 parts of aminosilane coupling agent.

[0043] Preferably, the hard segment of the TPAE-based polyamide copolymer and the soft segment of the MBPA multiblock polyamide copolymer are PA12 and PTMG, the number of blocks in the TPAE-based polyamide copolymer is 2, and the number of blocks in the MBPA multiblock polyamide copolymer is ≥12.

[0044] Preferably, the NP compound flame retardant is a mixture of piperazine pyrophosphate and melamine polyphosphate in a mass ratio of 2:1; the flame retardant synergist is polyketide resin.

[0045] Preferably, the bio-based fatty acid ester plasticizer is at least one of castor oil-based fatty acid methyl ester, soybean oil-based fatty acid methyl ester, and palm oil-based fatty acid ethyl ester.

[0046] Preferably, the ethylene-α-olefin copolymer-g-MAH is an ethylene-octene copolymer-g-MAH with a grafting rate of 1.5%-2.0%.

[0047] Preferably, the crosslinking agent includes at least one of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane or tert-butyl peroxyisopropyl carbonate.

[0048] Preferably, the initiator is tert-butyl peroxyisopropyl carbonate or benzoyl peroxide.

[0049] Preferably, the antioxidant is a 1:1 mixture of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (1010) and tris(2,4-di-tert-butylphenyl)phosphite (168);

[0050] The UV-resistant agent is at least one of benzotriazole UV234 or benzophenone UV531.

[0051] To illustrate the superior effects of the present invention, the following embodiments and comparative examples are provided.

[0052] The raw materials used in the following embodiments and comparative examples of the present invention can all be purchased from the market, and their sources are not specifically limited.

[0053] The following sources of raw materials are provided as examples:

[0054] Silicone rubber compound, Wacker Chemie;

[0055] TPAE-based polyamide, Evonik Degussa, Pebax® 1657;

[0056] MBPA (Multi-block Polyamide), Evonik Degussa, Pebax® 1657;

[0057] Piperazine pyrophosphate, Jiangsu Yake Technology, brand name YAK-APP;

[0058] Melamine polyphosphate, Zhejiang Wansheng Co., Ltd., brand name WS-MPP;

[0059] POK flame retardant synergist, Hyosung Korea, brand name POK M330A;

[0060] Ethylene-α-olefin copolymer - g-MAH, Dow Chemical, brand name Engage G-1900;

[0061] Aminosilane coupling agent, Dow Corning, brand name Z-6011;

[0062] Bio-based fatty acid ester plasticizer, Wilmar International, brand name BIO-Plasticizer C18;

[0063] Nano-montmorillonite, Fenghong New Materials, grade FH-300;

[0064] Crosslinking agent, double 25 crosslinking agent, AkzoNobel, brand name Perkadox® 14;

[0065] Antioxidant 1010:168, BASF, brand name Irganox® 1010+168;

[0066] Lubricant, Licowax PE 520;

[0067] UV protectant, Tinuvin 234.

[0068] The preparation methods of the silicone rubber / nylon composite elastomer materials in the following examples and comparative examples are as follows:

[0069] (1) Raw material pretreatment

[0070] The TPAE-based polyamide copolymer and the MBPA multi-block polyamide copolymer were dried in a forced-air drying oven at 80℃-100℃ for 4-6 hours until the moisture content was ≤0.1%.

[0071] Nano-montmorillonite and 2% by mass of its silane coupling agent were mixed at 50℃-60℃ and 100rpm for 30min to perform surface modification and improve the compatibility between nano-montmorillonite and the matrix.

[0072] (2) Premixing stage

[0073] Add silicone rubber compound (cut into 5cm³ pieces), nylon elastomer (crushed to a particle size <5mm), NP compound flame retardant, bio-based plasticizer, POK flame retardant synergist, phase structure modifier, and nano montmorillonite to the mixer.

[0074] To avoid plasticizer volatilization, set the temperature to 80-100℃, mix at 300 rpm for 10 minutes, then mix at high speed of 500 rpm for 20-30 minutes until the material is in uniform, semi-transparent granular form.

[0075] (3) One-time extrusion

[0076] Temperature settings for each section of a twin-screw extruder:

[0077] Feeding section 180-190℃, melting section 190-210℃, mixing section 200-220℃, homogenization section 210-220℃, die head temperature 220℃;

[0078] The screw speed is 200-300 rpm (shear rate controlled at 500-800 s⁻¹), the material residence time is 3-5 min, and after extrusion, it is cooled in a water bath (water temperature 25±2℃) and granulated (particle size 2-3 mm).

[0079] (4) Secondary mixing

[0080] The prepolymer granules are added to an internal mixer along with initiator, crosslinking agent (peroxide and co-crosslinking agent are premixed), antioxidant, UV stabilizer, and lubricant.

[0081] To avoid premature decomposition of peroxides, set the temperature to 100-120℃, the rotor speed to 50-80 rpm, and mix for 15-20 minutes until the material is free of obvious particles.

[0082] Transfer to a single-screw extruder at a temperature of 160-190℃ and a screw speed of 150 rpm for extrusion granulation. Dry the granules in a forced-air drying oven at 105℃ until the moisture content of the finished granules is ≤0.1%. Example

[0083] The raw material components of Examples 1-10 are shown in Table 1. Among them, the Shore hardness of the silicone rubber compound is 30A, the Shore hardness of the TPAE-based polyamide copolymer is 30D, and the Shore hardness of the MBPA multi-block polyamide copolymer is 30D with 12 blocks.

[0084] Table 1

[0085]

[0086] Comparative Example

[0087] Comparative Example 1

[0088] The mass ratio of TPAE-based polyamide copolymer to MBPA multiblock polyamide copolymer was 80:0, and other aspects were the same as in Example 1.

[0089] Comparative Example 2

[0090] The mass ratio of TPAE-based polyamide copolymer to MBPA multiblock polyamide copolymer was 48:32, and other aspects were the same as in Example 1.

[0091] Comparative Example 3

[0092] Except that the Shore hardness of the MBPA multiblock polyamide copolymer is 20D, everything else is the same as in Example 1.

[0093] Comparative Example 4

[0094] Except that the Shore hardness of the MBPA multiblock polyamide copolymer is 40D, everything else is the same as in Example 1.

[0095] Comparative Example 5

[0096] Except that the MBPA multiblock polyamide copolymer with 12 blocks was replaced with an MBPA multiblock polyamide copolymer with 8 blocks, the rest was the same as in Example 1.

[0097] Comparative Example 6

[0098] Except for the addition of 10 parts of ethylene-octene copolymer-g-MAH, without the addition of aminosilane coupling agent, the rest is the same as in Example 1.

[0099] Comparative Example 7

[0100] Except for the addition of 5 parts of aminosilane coupling agent, and without the addition of ethylene-octene copolymer-g-MAH, the rest is the same as in Example 1.

[0101] Comparative Example 8

[0102] Except for replacing the ethylene-α-olefin copolymer-g-MAH with an ungrafted ethylene-octene copolymer, the rest is the same as in Example 1.

[0103] Comparative Example 9

[0104] Except for the absence of nano-montmorillonite, the rest is the same as in Example 1.

[0105] Comparative Example 10

[0106] Except for the use of phthalate plasticizers instead of bio-based plasticizers, the rest is the same as in Example 1.

[0107] Comparative Example 11

[0108] Except for the addition of 55 parts of piperazine pyrophosphate, melamine polyphosphate was not added; otherwise, it was the same as in Example 1.

[0109] Comparative Example 12

[0110] Except for the addition of 55 parts of melamine polyphosphate, without the addition of piperazine pyrophosphate, the rest is the same as in Example 1.

[0111] Comparative Example 13

[0112] Except for replacing 55 parts of NP compound flame retardant with 55 parts of aluminum hydroxide, the rest is the same as in Example 1.

[0113] Comparative Example 14

[0114] Except for replacing 55 parts of NP compound flame retardant with 82.5 parts of aluminum hydroxide, the rest is the same as in Example 1.

[0115] Test case

[0116] The properties and characterization methods of the material in this invention are as follows:

[0117] Tensile strength was tested according to GB / T 528-2020 standard;

[0118] Elongation at break was tested according to GB / T 528-2020 standard;

[0119] Tear strength was tested according to GB / T 529-2008 standard;

[0120] UL94 flame retardant rating, tested according to UL94-2021 (V-0 / V-1 rating, 1.6mm thickness) standard;

[0121] Shore hardness A was tested according to GB / T 531.1-2019 standard;

[0122] Bending performance was tested according to GB / T 2951.4-2008;

[0123] Density was tested according to GB / T 1033.1-2008 standard;

[0124] Hardness change (30 days) was tested according to GB / T 531.1-2019 standard;

[0125] Melt flow rate: tested according to ISO 1133 standard (230°C, 2.16 kg);

[0126] Oil resistance: Oil resistance conditions, IRM902, 60℃*168H.

[0127] The performance data for Examples 1-10 are shown in Table 2.

[0128] Table 2

[0129]

[0130] The performance data for comparative examples 1-7 are shown in Table 3.

[0131] Table 3

[0132]

[0133] The performance data for comparative examples 8-14 are shown in Table 4.

[0134] Table 4

[0135]

[0136] As shown in Table 2, the composite elastomer materials of Examples 1-10 of this invention possess excellent comprehensive performance. Their UL94 vertical flammability rating all reach V-0 (1.6mm thickness), and their Shore A hardness is approximately 70, providing appropriate hardness support. The tensile breaking strength reaches approximately 18 MPa, the elongation at break is higher than 450%, and the tear strength is approximately 30 kN / m. They exhibit good bending performance, can withstand complex stress environments, and are suitable for applications such as wire and cable sheathing where high flexibility and durability are required. The low density ensures lightweight construction without compromising performance. The small hardness change rate ensures good dimensional stability. The melt flow rate is approximately 5 g / 10 min, ensuring good fluidity during processing and facilitating molding. The silicone rubber / nylon composite elastomer material of this invention achieves synergistic optimization and comprehensive balance of flame retardant properties, mechanical properties, oil resistance, and processing performance through specific component ratios.

[0137] As can be seen from the test results in Table 3, compared with Comparative Examples 1-5, Example 1 shows that the ratio, hardness and structure of TPAE-based polyamide copolymer and MBPA multi-block polyamide copolymer play a key role in the mechanical properties of the material. Imbalance in the ratio of TPAE to MBPA, deviation of MBPA hardness or insufficient number of MBPA blocks will affect the mechanical properties and flame retardant properties of the material.

[0138] Compared with Comparative Examples 6-7, Example 1 shows that, compared with the single-component compatibilizer used in Comparative Examples 6-7, the phase structure modifier in this invention uses ethylene-α-olefin copolymer-g-MAH and aminosilane coupling agent to form a two-way compatibility, which has better mechanical properties and flame retardant properties.

[0139] As shown in Table 4, compared with Comparative Example 8, the ungrafted ethylene-octene copolymer in Example 1 cannot effectively improve the interface, resulting in poor mechanical properties and flame retardant rating. Compared with Comparative Example 9, Example 1 demonstrates that nano-montmorillonite plays a crucial role in improving the flame retardant properties and oil resistance of the material. Compared with Comparative Example 10, Example 1 shows that the bio-based plasticizer has a significant impact on the mechanical properties and oil resistance of the material; the hardness of Comparative Example 10 shows a significant increase, affecting the long-term flexibility and reliability of the material. Compared with Comparative Examples 11-12, Example 1 demonstrates that the present invention uses a specific ratio of compounded flame retardants to achieve superior flame retardant properties in the material. Compared with Comparative Examples 13 and 14, Example 1 shows that the NP compound flame retardant used in this invention has better flame retardant performance, mechanical properties, processing performance, and oil resistance. Comparative Example 13 uses aluminum hydroxide of the same mass to replace the NP compound flame retardant, and the flame retardant performance is V-2. The burning time is prolonged and accompanied by dripping phenomenon, and the flame retardant efficiency is significantly reduced. Although Comparative Example 14 achieves a flame retardant rating of V-1 by adding a large amount of aluminum hydroxide, it leads to a significant decrease in mechanical properties.

[0140] As can be seen from the performance test results of the above embodiments and comparative examples, the composite elastomer materials of the various embodiments of the present invention effectively achieve a synergistic improvement in high toughness, excellent flame retardancy, good oil resistance and processing stability through the selection and combination of various raw materials.

[0141] Finally, it should be noted that the content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A high-toughness flame-retardant silicone rubber / nylon composite elastomer material, characterized in that, Composed of the following raw materials in parts by weight: The composition includes: 100 parts silicone rubber compound, 80-155 parts nylon elastomer, 55-85 parts NP compound flame retardant, 15-30 parts bio-based fatty acid ester plasticizer, 7-20 parts flame retardant synergist, 7-20 parts phase structure modifier, 5-10 parts nano montmorillonite, 1-3 parts crosslinking agent, 0.5-1 part initiator, 0.2-0.5 parts antioxidant, 0.8-1.6 parts UV stabilizer, and 0.2-0.5 parts lubricant. The silicone rubber compound is a methyl vinyl silicone rubber with a Shore hardness of 20A-40A and a vinyl content of 0.1%. The nylon elastomer is composed of 70-130 parts of TPAE-based polyamide copolymer and 10-25 parts of MBPA multiblock polyamide copolymer. The Shore hardness of the TPAE-based polyamide copolymer and the MBPA multiblock polyamide copolymer is 25D-35D. The hard segment of the TPAE-based polyamide copolymer and the MBPA multiblock polyamide copolymer is PA12 and the soft segment is PTMG. The number of blocks in the TPAE-based polyamide copolymer is 2, and the number of blocks in the MBPA multiblock polyamide copolymer is ≥12. The phase structure modifier comprises 5-15 parts of ethylene-α olefin copolymer-g-MAH and 2-5 parts of aminosilane coupling agent; the NP compound flame retardant is a compound of piperazine pyrophosphate and melamine polyphosphate in a mass ratio of 2:

1.

2. The silicone rubber / nylon composite elastomer material according to claim 1, characterized in that, The flame retardant synergist is polyketone resin.

3. The silicone rubber / nylon composite elastomer material according to claim 1, characterized in that, The bio-based fatty acid ester plasticizer is at least one of castor oil-based fatty acid methyl ester, soybean oil-based fatty acid methyl ester, and palm oil-based fatty acid ethyl ester.

4. The silicone rubber / nylon composite elastomer material according to claim 1, characterized in that, The ethylene-α-olefin copolymer-g-MAH is an ethylene-octene copolymer-g-MAH with a grafting rate of 1.5%-2.0%.

5. The silicone rubber / nylon composite elastomer material according to claim 1, characterized in that, The crosslinking agent includes at least one of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane or tert-butyl peroxyisopropyl carbonate.

6. The silicone rubber / nylon composite elastomer material according to claim 1, characterized in that, The initiator is tert-butyl peroxyisopropyl carbonate or benzoyl peroxide.

7. The silicone rubber / nylon composite elastomer material according to claim 1, characterized in that, The antioxidant is a 1:1 mixture of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl)phosphite; The UV-resistant agent is at least one of benzotriazole UV234 or benzophenone UV531.

8. A method for preparing a composite elastomer material as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Premixing stage: Add silicone rubber compound, nylon elastomer, NP compound flame retardant, bio-based plasticizer, flame retardant synergist, phase structure modifier and nano montmorillonite to a high-speed mixer and mix for 30 min to 40 min at 80℃-100℃ and 300 rpm-500 rpm. (2) One-time extrusion: The premixed material from step (1) is fed into a twin-screw extruder and melt-blended at 180℃-220℃ and screw speed of 200rpm-300rpm. After extrusion through the die, it is water-cooled and granulated to obtain prepolymer granules. (3) Secondary mixing: The prepolymer granules are added to an internal mixer with initiator, crosslinking agent, antioxidant, UV stabilizer and lubricant. The mixture is mixed at 100℃-120℃ and rotor speed of 50rpm-80rpm for 15min-20min, and then extruded and granulated again by a single screw extruder.

9. The application of high-toughness flame-retardant silicone rubber / nylon composite elastomer material in the outer sheath of wires and cables, characterized in that, The high-toughness flame-retardant silicone rubber / nylon composite elastomer material is the high-toughness flame-retardant silicone rubber / nylon composite elastomer material according to any one of claims 1-7.

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