A bend-resistant low-smoke halogen-free flame-retardant insulation material and a preparation method thereof

Abstract

This invention provides a bend-resistant, low-smoke, halogen-free flame-retardant insulating material, comprising the following components: 40-60 parts of polyolefin matrix resin, 10-25 parts of elastomer toughening component, 20-40 parts of inorganic flame-retardant filler, 2-8 parts of nano-layered charring agent, 0.5-2 parts of silane coupling agent, 2-6 parts of compatibilizer, 0.3-1 parts of antioxidant, and 0.2-1 parts of lubricant; wherein, the nano-layered charring agent is an organic intercalated modified nano-clay, used to form a dense char layer structure during combustion, and the silane coupling agent is used to modify the surface of the inorganic flame-retardant filler to improve the interfacial bonding performance between the filler and the polymer matrix. Compared with the prior art, this invention has the following beneficial effects: this material system achieves a unity of flexibility and flame-retardant performance through multiphase synergistic design, and is suitable for fields such as robot cables, drag chain cables, and new energy equipment harnesses.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology for wires and cables, specifically to a polyolefin insulating material with high bending resistance, low smoke, halogen-free flame retardant properties, and its preparation method. Background Technology

[0002] With the continuous development of industrial automation, robotics, rail transportation, and new energy equipment, the service frequency of cables in dynamic environments has significantly increased. Cables are subjected to repeated bending in cable chains, robotic arms, and rotating devices for extended periods, which can easily cause whitening, cracking, and insulation failure in ordinary insulation materials.

[0003] Existing low-smoke halogen-free polyolefin materials are based on polyethylene and require the addition of large amounts of inorganic flame-retardant fillers such as aluminum hydroxide. These materials have high rigidity but insufficient bending performance. With increased bending cycles, stress concentration occurs, causing the material surface to whiten or even crack.

[0004] Elastomer systems such as TPE, TPU, and silicone rubber have good flexibility, but they also suffer from high cost, narrow processing window, difficulty in matching flame retardant systems, and insufficient mechanical strength. Silicone rubber has low tensile strength and requires reinforcing fibers.

[0005] Meanwhile, traditional flame retardant systems have a loose char layer structure, high smoke density, and low light transmittance during combustion, making it difficult to meet low-smoke environmental protection requirements. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a bending-resistant, low-smoke, halogen-free flame-retardant insulating material, thereby solving the problems mentioned in the background section.

[0007] This invention is achieved through the following technical solution: a bend-resistant, low-smoke, halogen-free flame-retardant insulating material, comprising the following components: The composition includes 40-60 parts of polyolefin matrix resin, 10-25 parts of elastomer toughening component, 20-40 parts of inorganic flame retardant filler, 2-8 parts of nano-layered charring agent, 0.5-2 parts of silane coupling agent, 2-6 parts of compatibilizer, 0.3-1 part of antioxidant, and 0.2-1 part of lubricant. The nano-layered char-forming agent is an organic intercalation-modified nano-clay, used to form a dense char layer structure during combustion. The silane coupling agent is used to modify the surface of the inorganic flame-retardant filler to improve the interfacial bonding performance between the filler and the polymer matrix.

[0008] In a preferred embodiment, the polyolefin matrix resin is selected from one or a combination of two of polyolefin elastomer POE and linear low-density polyethylene LLDPE.

[0009] In a preferred embodiment, the elastomer toughening component is ethylene-vinyl acetate copolymer (EVA) or polyolefin elastomer (POE).

[0010] In a preferred embodiment, the inorganic flame-retardant filler is aluminum hydroxide and / or magnesium hydroxide.

[0011] In a preferred embodiment, the nano-layered char-forming agent is modified by organic cation intercalation and dispersed in the polymer matrix in an intercalation or exfoliation structure, thereby forming a continuous and dense barrier char layer during combustion.

[0012] In a preferred embodiment, the silane coupling agent is at least one of vinylsilane, aminosilane, or epoxysilane, used to form an organic-inorganic interface transition layer on the surface of the inorganic flame-retardant filler.

[0013] In a preferred embodiment, the compatibilizer is maleic anhydride-grafted polyethylene or maleic anhydride-grafted polypropylene, used to improve the compatibility between the components and enhance the stability of mechanical properties.

[0014] As a preferred embodiment, the material forms a multiphase network structure consisting of a continuous polyolefin matrix phase and a dispersed elastomer phase to improve the material's flexibility and reduce stress concentration during bending.

[0015] A method for preparing the above-mentioned material includes the following steps: S1, After drying the inorganic flame retardant filler and the nano-layered char-forming agent, a silane coupling agent is added for surface modification. S2, premix the polyolefin matrix resin, elastomer toughening component and compatibilizer; S3, the modified filler and additives are added to the above system and mixed; S4, the insulating material is obtained by melt blending and granulation using a twin-screw extruder.

[0016] The beneficial effects of adopting the above technical solution are as follows: This invention, through the composite design of a polyolefin matrix and an elastomer component, forms a multiphase structure with flexible characteristics within the material. The elastomer, dispersed within the matrix, bears deformation and disperses stress during repeated bending, reducing local stress concentration, slowing crack initiation and propagation. The material maintains structural integrity under long-term cyclic bending conditions, significantly improving its bending life.

[0017] The flame-retardant system consists of aluminum hydroxide and organically intercalated modified nano-clay. Aluminum hydroxide decomposes endothermally and releases moisture during heating, thus cooling and diluting the material. Nano-clay forms a layered structure under high temperature conditions and participates in the carbonization process, making the surface carbon layer more dense and continuous, blocking the transfer of heat and combustible gases, increasing the oxygen index of the material, reducing smoke release during combustion, and improving light transmittance.

[0018] After treatment with silane coupling agents, inorganic fillers form a stable interface with the polymer matrix, improving filler dispersion and enhancing interfacial bonding, thus maintaining certain mechanical properties even under high filling conditions. The introduction of compatibilizers improves the compatibility between multi-component systems, making melt processing more stable and resulting in products with uniform structure.

[0019] This material system achieves a balance between flexibility, flame retardancy, and low smoke characteristics, making it suitable for insulation layers of wires and cables that require frequent bending. It also exhibits good stability and reliability during long-term use. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of a bending-resistant, low-smoke, halogen-free flame-retardant insulating material according to the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0023] This invention provides a technical solution: a flexurally resistant, low-smoke, halogen-free flame-retardant insulating material, comprising the following components: The composition includes 40-60 parts of polyolefin matrix resin, 10-25 parts of elastomer toughening component, 20-40 parts of inorganic flame retardant filler, 2-8 parts of nano-layered charring agent, 0.5-2 parts of silane coupling agent, 2-6 parts of compatibilizer, 0.3-1 part of antioxidant, and 0.2-1 part of lubricant. The nano-layered char-forming agent is an organic intercalation-modified nano-clay, used to form a dense char layer structure during combustion. The silane coupling agent is used to modify the surface of the inorganic flame-retardant filler to improve the interfacial bonding performance between the filler and the polymer matrix.

[0024] The polyolefin matrix resin is selected from one or a combination of two of polyolefin elastomer POE and linear low-density polyethylene LLDPE.

[0025] The toughening component of the elastomer is ethylene-vinyl acetate copolymer (EVA) or polyolefin elastomer (POE).

[0026] The inorganic flame-retardant filler is aluminum hydroxide and / or magnesium hydroxide.

[0027] The nano-layered char-forming agent is modified by organic cationic intercalation and dispersed in the polymer matrix in an intercalation or exfoliation structure, thereby forming a continuous and dense barrier char layer during combustion.

[0028] The silane coupling agent is at least one of vinylsilane, aminosilane, or epoxysilane, used to form an organic-inorganic interface transition layer on the surface of inorganic flame-retardant fillers.

[0029] The compatibilizer is maleic anhydride-grafted polyethylene or maleic anhydride-grafted polypropylene, used to improve the compatibility between the components and enhance the stability of mechanical properties.

[0030] The material forms a multiphase network structure consisting of a continuous polyolefin matrix phase and a dispersed elastomer phase to improve the material's flexibility and reduce stress concentration during bending.

[0031] Please see Figure 1 A method for preparing the above-mentioned material includes the following steps: S1, After drying the inorganic flame retardant filler and the nano-layered char-forming agent, a silane coupling agent is added for surface modification. S2, premix the polyolefin matrix resin, elastomer toughening component and compatibilizer; S3, the modified filler and additives are added to the above system and mixed; S4, the insulating material is obtained by melt blending and granulation using a twin-screw extruder.

[0032] As one embodiment of the present invention: The present invention, through multi-component synergistic design, enables the material to maintain low-smoke, halogen-free flame-retardant properties while improving flexibility and bending resistance. The following description is based on specific embodiments.

[0033] Example 1 includes the following components: A method for preparing the above-mentioned material includes the following steps: (1) placing aluminum hydroxide flame retardant and organic intercalated modified nano clay in a forced-air drying oven and drying at 100°C for 2 hours; (2) Add the dried powder to a high-speed mixer, add silane coupling agent, and mix for 15 minutes at 800 rpm to make the coupling agent evenly coat the powder surface; (3) Add the polyolefin elastomer, ethylene-vinyl acetate copolymer and maleic anhydride grafted polyethylene into a mixer for premixing; (4) Add the treated flame retardant filler, antioxidant, and lubricant, and mix for 10 minutes; (5) Add the mixture to a twin-screw extruder and melt-blend it in a temperature range of 160-190°C; (6) Extrusion granulation, cooling, to obtain insulating material particles.

[0034] Example 2 includes the following components: Comparative Example 1 Performance tests were conducted on Examples 1 and 2, and on a comparative basis, as detailed below: 1. Bending performance test The test was conducted using a reciprocating bending test apparatus: specimen length: 300 mm; bending radius: 10 mm; bending angle: ±90°; frequency: 60 cycles / minute. The sample is fixed at both ends of the equipment and subjected to continuous bending cycles. The number of cycles when breakage or insulation failure occurs is recorded.

[0035] 2. Tensile property test Perform according to national standard methods: The specimens were prepared as dumbbell-shaped specimens; the tensile speed was 50 mm / min; the tensile strength and elongation at break were recorded.

[0036] 3. Oxygen Index Test The oxygen index was tested using an oxygen index meter. The sample is placed vertically; the oxygen to nitrogen ratio is adjusted; the minimum oxygen concentration required to maintain the continuous combustion of the material is determined. 4. Smoke density (transmittance) test Conducted according to the low-smoke performance testing method: Place the sample in a sealed combustion chamber; ignite the sample; record the change in transmittance using a photoelectric detection device; take the transmittance during the stable phase as the result.

[0037] Mechanical performance test results table As shown in the table above, the elongation at break of the material in the example is significantly higher than that in the comparative example, indicating that the elastomer component forms a flexible structure, improving the material's ductility. The tensile strength is also improved, suggesting that the nanofiller and interface modification enhance the overall structural stability.

[0038] Bending performance test results table As shown in the table above, the bending life of the material in the example is significantly improved, reaching over 30,000 cycles. The comparative material exhibits obvious whitening and cracking during bending. This is because the elastomer network structure can buffer stress, and the nano-clay enhances structural stability, thereby extending the service life.

[0039] Flame retardant properties and smoke density table As shown in the table above, the oxygen index and light transmittance of the materials in the examples are significantly improved. The nano-clay forms a dense char layer structure during combustion, which blocks heat and gas diffusion and reduces smoke generation. The comparative example has a loose char layer and higher smoke density.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A flexurally resistant, low-smoke, halogen-free flame-retardant insulating material, characterized in that, It includes the following components: The composition includes 40-60 parts of polyolefin matrix resin, 10-25 parts of elastomer toughening component, 20-40 parts of inorganic flame retardant filler, 2-8 parts of nano-layered charring agent, 0.5-2 parts of silane coupling agent, 2-6 parts of compatibilizer, 0.3-1 part of antioxidant, and 0.2-1 part of lubricant. The nano-layered char-forming agent is an organic intercalation-modified nano-clay, used to form a dense char layer structure during combustion. The silane coupling agent is used to modify the surface of the inorganic flame-retardant filler to improve the interfacial bonding performance between the filler and the polymer matrix.

2. The flexurally resistant, low-smoke, halogen-free flame-retardant insulating material as described in claim 1, characterized in that: The polyolefin matrix resin is selected from one or a combination of two of polyolefin elastomer POE and linear low-density polyethylene LLDPE.

3. The bending-resistant, low-smoke, halogen-free flame-retardant insulating material as described in claim 1, characterized in that: The toughening component of the elastomer is ethylene-vinyl acetate copolymer (EVA) or polyolefin elastomer (POE).

4. The flexurally resistant, low-smoke, halogen-free flame-retardant insulating material as described in claim 1, characterized in that: The inorganic flame-retardant filler is aluminum hydroxide and / or magnesium hydroxide.

5. The bending-resistant, low-smoke, halogen-free flame-retardant insulating material as described in claim 2, characterized in that: The nano-layered char-forming agent is modified by organic cation intercalation and dispersed in the polymer matrix in an intercalation or exfoliation structure, thereby forming a continuous and dense barrier char layer during combustion.

6. The flexurally resistant, low-smoke, halogen-free flame-retardant insulating material as described in claim 1, characterized in that: The silane coupling agent is at least one of vinylsilane, aminosilane, or epoxysilane, and is used to form an organic-inorganic interface transition layer on the surface of the inorganic flame-retardant filler.

7. The flexurally resistant, low-smoke, halogen-free flame-retardant insulating material as described in claim 3, characterized in that: The compatibilizer is maleic anhydride-grafted polyethylene or maleic anhydride-grafted polypropylene, used to improve the compatibility between the components and enhance the stability of mechanical properties.

8. The flexurally resistant, low-smoke, halogen-free flame-retardant insulating material as described in claim 1, characterized in that: The material forms a multiphase network structure consisting of a continuous polyolefin matrix phase and a dispersed elastomer phase to improve the material's flexibility and reduce stress concentration during bending.

9. A method for preparing the material according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1, After drying the inorganic flame retardant filler and the nano-layered char-forming agent, a silane coupling agent is added for surface modification. S2, premix the polyolefin matrix resin, elastomer toughening component and compatibilizer; S3, the modified filler and additives are added to the above system and mixed; S4, the insulating material is obtained by melt blending and granulation using a twin-screw extruder.

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