Irradiation crosslinking low-smoke halogen-free polyolefin insulation material for B1-grade flame-retardant cotton covered wire and preparation method of radiation crosslinking low-smoke halogen-free polyolefin insulation material

Abstract

The invention provides an irradiation crosslinking low-smoke halogen-free polyolefin insulation material for a B1-grade flame-retardant cotton covered wire and a preparation method thereof, the irradiation crosslinking low-smoke halogen-free polyolefin insulation material for the B1-grade flame-retardant cotton covered wire comprises the following components in parts by weight: 10-15 parts of ethylene-vinyl acetate copolymer A, 10-15 parts of ethylene-vinyl acetate copolymer B, 5-8 parts of ethylene-propylene-diene monomer rubber, 1-3 parts of a flame retardant, 1-3 parts of an antioxidant, 1-3 parts of a lubricant and 1-3 parts of a lubricant. The halogen-free flame-retardant cable material is prepared from the following components in parts by weight: 5 parts of maleic anhydride grafted polyolefin, 45-60 parts of magnesium hydroxide, 30-40 parts of aluminum hydroxide, 5-10 parts of antimony trioxide, 1-2 parts of a smoke suppressor, 0.1-1 part of an assistant crosslinker, 1-2 parts of an antioxidant, 2-4 parts of a lubricant and 1-2 parts of a processing aid. The prepared B1-level irradiation crosslinking low-smoke halogen-free polyolefin insulating material has excellent comprehensive performance, excellent mechanical performance, high temperature aging resistance and low smoke amount and total heat release amount, and can meet B1-level combustion, and the dripping level is d0. The cable has good fluidity and formability in the processing process, and is especially suitable for the fields of building wiring and the like.

Description

Technical Field

[0001] This invention relates to the field of wire and cable insulation materials, specifically to a B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires and its preparation method. Background Technology

[0002] With increasingly stringent requirements for building electrical safety, higher standards have been set for the flame retardancy, low smoke, halogen-free, and environmental performance of wires and cables. Especially in densely populated areas and important buildings, wires and cables are required to achieve a B1 flame retardancy rating (according to GB 31247-2014 "Classification of Burning Performance of Cables and Optical Fibers"). This necessitates building materials with excellent flame retardant properties, extremely low smoke density, and low toxicity. Currently, low-smoke halogen-free flame-retardant polyolefin materials used for wire and cable insulation, especially for small-diameter and thin-walled building electrical wires, typically only meet the B2 rating or lower flame retardancy requirements in bundled burning tests, making it difficult to consistently and reliably achieve a B1 flame retardancy rating.

[0003] In recent years, fires caused by aging wires and cables have been increasing. To reduce the incidence of fires and the mortality rate during fires, it is necessary to develop wire insulation materials that meet the B1 flame retardant rating to improve application safety and service life. To achieve B1 flame retardancy, a large amount of inorganic flame retardants, typically aluminum hydroxide and magnesium hydroxide, are usually added. These materials have poor compatibility with the resin matrix and poor dispersion within it, leading to a significant reduction in the material's mechanical properties, toughness, heat resistance, and processability. The long-term operating temperature of ordinary thermoplastic polyolefins typically does not exceed 90℃, limiting their application in more demanding applications. Irradiation crosslinking technology can effectively improve the heat resistance, mechanical strength, and stress cracking resistance of polyolefins. Therefore, developing an irradiated crosslinked polyolefin insulation material that meets both low-smoke, halogen-free B1 flame retardancy requirements and possesses excellent electrical properties, processability, and heat resistance is of great significance for improving the safety and reliability of electrical wiring. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for building wires and its preparation method. The obtained B1-grade irradiated cross-linked low-smoke halogen-free polyolefin insulation material has excellent comprehensive properties, superior mechanical properties, high-temperature aging resistance, low smoke emission and total heat release, and meets the B1-grade combustion requirement with a dripping grade of d0. It exhibits good flowability and formability during processing, making it particularly suitable for applications such as building wiring. Furthermore, this invention also provides a preparation process for this insulation material to achieve industrial-scale production.

[0005] The technical solution of this invention is:

[0006] This invention provides a B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for building wires, comprising the following components by weight:

[0007]

[0008] This invention also provides a method for preparing a B1-grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for electrical wires, the preparation method comprising the following steps:

[0009] Ethylene-vinyl acetate copolymer A, ethylene-vinyl acetate copolymer B, ethylene propylene diene monomer (EPDM) rubber, and maleic anhydride grafted polyolefin are initially mixed evenly. Then, a mixture of magnesium hydroxide, aluminum hydroxide, antimony trioxide, smoke suppressant, antioxidant, crosslinking aid, lubricant, and processing aid is added. After thorough mixing, the mixture is heated and kneaded, then extruded and granulated by single and twin screw extrusion, dried, and sieved to obtain B1 grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for electrical wires.

[0010] The present invention also provides the application of the B1-grade flame-retardant electrical wire irradiated cross-linked low-smoke halogen-free polyolefin insulation material according to the present invention in cables.

[0011] By adopting the aforementioned technical solution, the beneficial effects of the present invention are:

[0012] The B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for building wires of this invention has excellent comprehensive properties, good mechanical properties, resistance to high-temperature aging, good flame retardancy, and good processability. Specifically, under non-irradiated conditions, the tensile strength and elongation at break of the insulation material are >9MPa and >160%, respectively; after irradiation cross-linking, the insulation material still has superior mechanical properties after being kept at a high temperature of 135°C for 168 hours, with a mechanical property change rate of <25%; it has good flame retardancy, with an oxygen index >45, and after cabling, it meets the requirements for bundled Class A combustion and Class B1 combustion, with a dripping grade of d0.

[0013] The B1 insulating material of this invention uses unmodified magnesium hydroxide and aluminum hydroxide as the main flame retardants, and does not contain any phosphorus-nitrogen flame retardants. Simultaneously, a smoke suppressant is added to further reduce smoke production. Compared to ordinary insulating materials, this insulating material has a smoke density of less than 30 m³ / s. 2 The total heat release is less than 15 MJ. The insulation material using the optimized scheme has a tensile strength of 9.96 MPa, an elongation at break of 172%, and a total smoke generation and heat release of only 24.5 mJ. 2 With a strength of 7.30MJ and meeting the requirements of B1 and d0, it possesses good mechanical and flame-retardant properties while satisfying fire protection requirements. Detailed Implementation

[0014] The following details the implementation methods of the B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for building wires and its preparation method provided by the present invention.

[0015] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0016] [B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires]

[0017] This invention provides a B1-grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for electrical wires, comprising ethylene-vinyl acetate copolymer A, ethylene-vinyl acetate copolymer B, ethylene propylene diene monomer (EPDM) rubber, maleic anhydride grafted polyolefin, magnesium hydroxide, aluminum hydroxide, antimony trioxide, smoke suppressant, crosslinking aid, antioxidant, lubricant, and processing aid.

[0018] This invention relates to an irradiated crosslinked polyolefin insulation material, which uses a blend of ethylene-vinyl acetate copolymer and ethylene propylene diene monomer (EPDM) rubber as the base material to improve the material's mechanical properties and processability. Maleic anhydride polyolefin grafting agent is used to improve the compatibility of organic-inorganic composite materials. The halogen-free flame retardant is mainly a mixture of aluminum hydroxide / magnesium hydroxide and antimony trioxide, which improves the flame retardant rating through a synergistic flame retardant effect. The hexagonal magnesium hydroxide is not surface-modified, effectively improving flame retardancy and reducing smoke release. Antimony trioxide significantly reduces heat release during combustion, and the addition of a small amount of smoke suppressant further reduces smoke production. Appropriate amounts of crosslinking aid, antioxidant, lubricant, and processing aid are added to give the resulting irradiated crosslinked low-smoke halogen-free polyolefin insulation material excellent comprehensive properties and good processability. Specifically, an irradiated crosslinked low-smoke halogen-free polyolefin insulation material for B1-grade flame-retardant building wires comprises the following components by weight:

[0019] The weight of ethylene-vinyl acetate copolymer A is 10-15 parts, and can be selected as 10-13 parts, 13-15 parts, etc. For example, 10, 11, 12, 13, 14 or 15 parts.

[0020] The weight of ethylene-vinyl acetate copolymer B is 10-15 parts, and can be selected as 10-12 parts, 12-15 parts, etc. For example, 10, 11, 12, 13, 14 or 15 parts.

[0021] The weight of EPDM rubber is 5-8 parts, and can be selected as 5-7 parts, 7-8 parts, 5-6 parts, 6-8 parts, etc. For example, 5, 6, 7 or 8 parts.

[0022] The weight of maleic anhydride-grafted polyolefin is 5 parts.

[0023] The magnesium hydroxide is in the form of 45-60 parts by weight, and can be selected as 45-55 parts, 55-60 parts, 45-50 parts, 50-55 parts, 55-60 parts, etc. For example, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60 parts.

[0024] The weight of aluminum hydroxide is 30-40 parts, and can be selected as 30-35 parts, 35-40 parts, etc. For example, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40 parts.

[0025] The weight of antimony trioxide is 5-10 parts, which can be selected as 5-7 parts, 7-10 parts, 5-8 parts, 8-10 parts, etc. For example, 5, 6, 7, 8, 9 or 10 parts.

[0026] The smoke suppressant is dispensed in quantities of 1-2 parts by weight, or alternatively 1-1.5 parts or 1.5-2 parts. For example, 1, 1.2, 1.5 or 2 parts.

[0027] The crosslinking agent is 0.1-1 part by weight, and can be selected as 0.1-0.5 parts, 0.5-1 parts, etc. For example, 0.1, 0.5, 0.8 or 1 part.

[0028] The antioxidant is present in 1-2 parts by weight, and can be selected as 1-1.2 parts, 1.2-2 parts, 1-1.5 parts, or 1.5-2 parts, etc. For example, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 parts.

[0029] The lubricant is present in quantities of 2-4 parts by weight, and can be selected as 2-3 parts or 3-4 parts, etc. For example, 2, 2.5, 3, 3.5 or 4 parts.

[0030] The processing aid is present in 1-2 parts by weight, optionally 1-1.5 parts or 1.5-2 parts. For example, 1, 1.5 or 2.0 parts.

[0031] In one specific embodiment of the present invention, the component, by weight, comprises the following components:

[0032]

[0033]

[0034] The B1-grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for electrical wires provided by this invention has an VA content of 28-33% for the ethylene-vinyl acetate copolymer A, optionally 28-30% or 30-33%, etc. The melt flow index is 1-4 g / 10 min, for example, 1-2 g / 10 min or 2-4 g / 10 min. Optionally, the ethylene-vinyl acetate copolymer A is selected from one or more of Mitsui Dow's EVA421 and EVA7470K.

[0035] The B1-grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for electrical wires provided by this invention has a VA content of not less than 40% for the ethylene-vinyl acetate copolymer B and a melt flow index greater than or equal to 4 g / 10 min. Optionally, the ethylene-vinyl acetate copolymer B is selected from one or more of Dow Chemical's 40L-03 and Mitsui Chemicals' 40LX.

[0036] In the B1-grade flame-retardant electrical wire irradiated crosslinked low-smoke halogen-free polyolefin insulation material provided by this invention, the EPDM rubber is either Keltan's 2470C or Vistalon's 7001.

[0037] In the B1-grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for electrical wires provided by this invention, the grafting rate of the maleic anhydride-grafted polyolefin is greater than or equal to 0.8%. Optionally, the maleic anhydride-grafted polyolefin is selected from one or more of Nenkatsu's MC509 and Mitsui Chemicals' MH7020.

[0038] The B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires provided by this invention uses a mixture of magnesium hydroxide, aluminum hydroxide, antimony trioxide, and a smoke suppressant as the halogen-free flame retardant. The magnesium hydroxide is not surface-modified, which improves its flame-retardant properties. The use of antimony trioxide and the smoke suppressant effectively reduces heat release and smoke production. Optionally, the D50 particle size of the aluminum hydroxide, magnesium hydroxide, and antimony trioxide is 0.5–1.5 μm. The smoke suppressant is selected from one or more of molybdenum trioxide and ammonium octamolate.

[0039] In the B1-grade flame-retardant electrical wire irradiation crosslinking low-smoke halogen-free polyolefin insulation material provided by the present invention, the crosslinking agent is selected from one or more of trimethylolpropane trimethacrylate, triallyl isocyanurate, and dicumyl peroxide.

[0040] The B1-grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for electrical wires provided by this invention includes a primary antioxidant and a secondary antioxidant. Optionally, the primary antioxidant is selected from a mixture of hindered phenols and copper inhibitors, wherein the hindered phenols are selected from hindered phenols 1010, 1076, or 330; and the copper inhibitor is copper inhibitor 1024. The secondary antioxidant is selected from any one or a mixture of at least two of thioester-type DSTP, DLTP, and phosphite ester 168.

[0041] In the B1-grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for electrical wires provided by this invention, the lubricant is one or both of the following: polyethylene wax with a molecular weight greater than or equal to 50,000 or silicone masterbatch with a siloxane content of not less than 50%. The polyethylene wax is, for example, imported polyethylene wax. Optionally, the lubricant is silicone masterbatch with a siloxane content of 50%, and the carrier is linear low-density polyethylene, model SR-500 from Guangzhou Yinyuan.

[0042] In the B1-grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for building wires provided by this invention, the processing aid is fluorine-free PPA, which aims to improve processing performance and eliminate die casting during extrusion. For example, it can be BYK-MAX P 4109 from BYK Chemicals.

[0043] [Preparation method of irradiated cross-linked low-smoke halogen-free polyolefin insulation material for B1 grade flame-retardant building wires]

[0044] This invention also provides a method for preparing B1-grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for building wires. The preparation method includes the following steps: pre-mixing ethylene-vinyl acetate copolymer A, ethylene-vinyl acetate copolymer B, ethylene propylene diene monomer (EPDM) rubber, and maleic anhydride grafted polyolefin in parts by weight until uniform; then adding a mixture of magnesium hydroxide, aluminum hydroxide, antimony trioxide, smoke suppressant, antioxidant, crosslinking aid, lubricant, and processing aid; mixing thoroughly and uniformly; then kneading for 10-15 minutes; the temperature of the rubber compound exiting the kneading drum is 165-175°C; and finally granulating by single and twin screw extrusion, drying, and sieving to obtain B1-grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for building wires.

[0045] In the preparation method provided by this invention, the twin-screw has a diameter of 50 mm, an aspect ratio of 25 / 1, uses a low-smoke halogen-free screw, and the temperature is set to 110–170 °C. Temperature settings for other specifications of twin-screw extruders can be adjusted based on these settings.

[0046] In the preparation method provided by this invention, the drying temperature is 40-50℃.

[0047]

use

[0048] This invention also provides the application of the B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires as described in the first aspect of this invention in cables. This cable material is designed to meet the urgent needs of the construction industry for lightweight and high-safety cable materials.

[0049] The beneficial effects of the present invention will be further illustrated below with reference to the embodiments.

[0050] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described in detail below with reference to embodiments. However, it should be understood that the embodiments of this invention are merely for illustrative purposes and not for limiting the invention, and the embodiments are not limited to those given in the specification. Unless otherwise specified, specific experimental or operational conditions in the embodiments were prepared under conventional conditions or according to the conditions recommended by the material supplier.

[0051] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting 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.

[0052] In the following embodiments, unless otherwise specified, all the raw materials of the present invention are commercially available or prepared according to conventional methods in the art.

[0053] Example 1

[0054] The B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires described in this embodiment comprises, by weight, the following components: 13 parts of ethylene-vinyl acetate copolymer A, 12 parts of ethylene-vinyl acetate copolymer B, 6 parts of ethylene propylene diene monomer (EPDM) rubber, 5 parts of maleic anhydride grafted polyolefin, 55 parts of magnesium hydroxide, 35 parts of aluminum hydroxide, 8 parts of antimony trioxide, 2 parts of smoke suppressant, 0.3 parts of cross-linking agent, 1.2 parts of antioxidant, 3 parts of lubricant, and 1.5 parts of processing aid.

[0055] Among them, the VA content of ethylene-vinyl acetate copolymer A is 28%, and the model is Mitsui Dow EVA421; the VA content of ethylene-vinyl acetate copolymer B is 40%, and the model is Dow Chemical 40L-03. Two ethylene-vinyl acetate copolymers were blended to improve the inorganic filler content, optimize flame retardant properties, and enhance the mechanical properties of the material. The EPDM rubber used was Keltan 2470C. The maleic anhydride-grafted polyolefin had a grafting rate of 0.8% and was Nengzhiguang MC509. The antioxidant was a blend of 0.6 parts hindered phenol 1010, 0.4 parts thioester DLTP, and 0.2 parts copper inhibitor 1024. The co-crosslinking agent was triallyl isocyanurate (TAIC). The lubricant was a silicone masterbatch with 50% siloxane content, and the carrier was linear low-density polyethylene, Guangzhou Yinyuan SR-500. Magnesium hydroxide was not surface-modified, with a D50 particle size of 0.5–1.5 μm. The preferred D50 particle size for aluminum hydroxide and antimony trioxide was 0.5–1.5 μm. Ammonium octamolybdate was used as the smoke suppressant and purchased from Jiangsu Kunyu Metal. The processing aid selected was fluorine-free PPA, model BYK-MAX P 4109, purchased from BYK Chemicals.

[0056] The preparation method of the B1-grade flame-retardant building wire irradiated cross-linked low-smoke halogen-free polyolefin insulation material in this embodiment is as follows:

[0057] According to the formula, ethylene-vinyl acetate copolymer, ethylene propylene diene monomer (EPDM) rubber, and maleic anhydride grafting agent are mixed evenly. Then, a mixture of lubricant, antioxidant, crosslinking aid, and silane coupling agent is added. After being thoroughly mixed evenly in an internal mixer, a halogen-free flame retardant is added. After internal mixing, extrusion, granulation, drying, and sieving, the B1 grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for building wires is obtained.

[0058] Example 2

[0059] The difference between this embodiment and Embodiment 1 is that the content of ethylene-vinyl acetate copolymer is changed. The content of ethylene-vinyl acetate copolymer A is reduced by 3 parts and added to ethylene-vinyl acetate copolymer B. Everything else is the same as in Embodiment 1.

[0060] Example 3

[0061] The difference between this embodiment and Embodiment 1 is that the amount of magnesium hydroxide is increased by 5 parts and the amount of aluminum hydroxide is decreased by 5 parts, while the rest is the same as in Embodiment 1.

[0062] Example 4

[0063] The difference between this embodiment and Embodiment 1 is that the amount of antimony trioxide is reduced by 3 parts, the amount of aluminum hydroxide is increased by 2 parts, and the amount of magnesium hydroxide is increased by 1 part. Everything else is the same as in Embodiment 1.

[0064] Example 5

[0065] The difference between this embodiment and Embodiment 1 is that the amount of smoke suppressant is reduced by 1 part and added to magnesium hydroxide; otherwise, they are the same as in Embodiment 1.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 lies in the change of resin content. The specific composition is as follows: 13 parts of ethylene-vinyl acetate copolymer A, 12 parts of ethylene-vinyl acetate copolymer B, 6 parts of ethylene propylene diene monomer (EPDM) rubber, 5 parts of maleic anhydride grafted polyolefin, 35 parts of magnesium hydroxide, 55 parts of aluminum hydroxide, 8 parts of antimony trioxide, 2 parts of smoke suppressant, 0.3 parts of crosslinking agent, 1.2 parts of antioxidant, 3 parts of lubricant, and 1.5 parts of processing aid.

[0068] The specific types of each component are roughly the same as in Example 1, except that the amount of magnesium hydroxide is reduced by 20 parts and added to aluminum hydroxide.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 1 is that it does not contain EPDM rubber. The reduced amount of EPDM rubber is increased on average in the two ethylene-vinyl acetate copolymers to ensure that the total amount of resin matrix remains unchanged. Everything else is the same as in Example 1.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 1 is that it does not contain antimony trioxide. The reduced amount of antimony trioxide is increased on average in aluminum hydroxide and magnesium hydroxide, ensuring that the total amount of flame retardant remains unchanged. Everything else is the same as in Example 1.

[0073] Comparative Example 4

[0074] The difference between this comparative example and Example 1 is that the type of magnesium hydroxide is changed, and modified magnesium hydroxide S-6 is used; otherwise, they are the same as in Example 1.

[0075] Comparative Example 5

[0076] The difference between this comparative example and Example 1 is that the amount of magnesium hydroxide is reduced by 5 parts and the amount of EPDM rubber is increased by 5 parts, while the rest are the same as in Example 1.

[0077] The performance of the B1-grade flame-retardant electrical wire insulation materials prepared in Examples 1-5 and Comparative Examples 1-5 was tested by radiation crosslinking low-smoke halogen-free polyolefin insulation. The test results are shown in Table 1. To test the B1-grade flammability of the materials, the above materials were processed into cables using a low-smoke halogen-free extruder. The screw zone temperature of the extruder was set to 125℃, 135℃, 145℃, 155℃, 165℃, and 170℃. The screw diameter was 50mm, the length-to-diameter ratio was 25 / 1, and the die head zone temperature was set to 170℃, 170℃, and 175℃. A 2.5mm diameter was extruded using a U7 non-adjustable die head. 2 The insulated wire has a wall thickness of 0.8-0.9 mm and a core / sleeve diameter of 2.0 mm / 3.4 mm. The wire undergoes subsequent cross-linking via irradiation, with an irradiation dose of 2-5 Mrad. The B1 flammability data for the cross-linked polyolefin insulated wire are shown in Table 2.

[0078] The testing standards are as follows:

[0079] The testing standards for tensile strength and elongation at break are in accordance with GB / T 1040, the testing standards for oxygen index are in accordance with GB / T2406.2-2009, and the testing standards for B1-level combustion performance are in accordance with GB / T 31248-2014.

[0080] Table 1: Comparative Analysis of Insulation Material Performance

[0081]

[0082] Table 2: Comparative Analysis of B1 Flammability of Electrical Wires

[0083]

[0084]

[0085] As can be seen from Tables 1 and 2, the B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for building wiring described in this invention has excellent comprehensive performance and outstanding flame-retardant properties, making it particularly suitable for applications such as building wiring. The embodiments described in this invention meet the requirements of national standards GB / T 32129 and GB / T 31247 in all their performance indicators.

[0086] As shown in Example 2 and Comparative Example 2, ethylene-vinyl acetate copolymer has a positive effect on flame retardant properties, while ethylene propylene diene monomer (EPDM) rubber has the opposite effect. However, their effects on mechanical properties are opposite. In particular, EPDM rubber plays an important role in improving powder filling rate and elongation at break. In Comparative Example 2, after replacing the rubber, the elongation at break decreased directly from 172% in Example 1 to 143%. Although it can meet the B1 flammability rating, the mechanical properties are unqualified.

[0087] As demonstrated by Examples 1 and 4, unmodified magnesium hydroxide exhibits significant advantages in flame retardancy. In Comparative Example 4, the use of modified magnesium hydroxide S-6 resulted in substandard heat release rate and total heat release, with combustion dripping grade only reaching d2, and severely deteriorated tensile strength and oxygen index. Specifically, the total heat release in Comparative Example 4 increased from 7.30 MJ in Example 1 to 16.64 MJ, and the total smoke production increased from 16.95 MJ in Example 1. 2 Increased to 35.42m 2 .

[0088] Based on the data from Example 3 and Comparative Example 1, reducing the amount of magnesium hydroxide significantly affects the indicators related to combustion heat release. In Comparative Example 1, after reducing the amount of magnesium hydroxide by 20 parts, the B1-level combustion data showed a significant increase in both the heat release rate and the peak heat release, directly leading to the failure of B1-level combustion. The heat release rate increased from 7.30 MJ in Example 1 to 15.37 MJ, and the peak heat release rate increased from 26.27 kW in Example 1 to 34.26 kW.

[0089] The results from Examples 4, 5, and Comparative Example 3 show that a small amount of antimony trioxide can significantly reduce the total heat release during combustion and improve combustion dripping, while having little impact on mechanical properties. Comparing the data from Example 1 and Comparative Example 3, without the addition of antimony trioxide, the total heat release was unacceptable, increasing from 7.30 MJ to 19.87 MJ, and the combustion rating deteriorated from d0 to d2. Furthermore, the peak heat release rate was also unacceptable, and the combustion damage length and oxygen index decreased significantly. However, antimony trioxide has a negative impact on smoke production, as shown in Example 5. Using it in combination with a smoke suppressant can effectively improve flue gas production.

[0090] The results of Example 1, Comparative Example 2, and Comparative Example 5 show that a high level of inorganic material filling is required to meet the B1 flammability standard. In Comparative Example 5, although the mechanical properties improved after the inorganic material filling rate decreased by 5 parts, the flame retardant properties of the material decreased, and all indicators in the B1 flammability test failed. The oxygen index dropped from 48 to 40, and the dripping grade changed from d0 to d2.

[0091] This invention illustrates the detailed process equipment and process flow through the above embodiments. However, this invention is not limited to the detailed process equipment and process flow described above, meaning that this invention does not necessarily depend on the detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, all fall within the protection scope and disclosure scope of this invention.

[0092] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0093] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0094] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires, characterized in that, By weight, it includes the following components:

2. The B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires according to claim 1, characterized in that, The VA content of the ethylene-vinyl acetate copolymer A is 28-33%, and the melt index is 1-4 g / 10 min; And / or, the VA content of the ethylene-vinyl acetate copolymer B is not less than 40%, and the melt index is greater than or equal to 4 g / 10 min.

3. The B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires according to claim 1, characterized in that, The grafting rate of the maleic anhydride-grafted polyolefin is greater than or equal to 0.8%.

4. The B1-grade flame-retardant electrical wire irradiation crosslinking low-smoke halogen-free polyolefin insulation material according to claim 1, wherein the D50 particle size of aluminum hydroxide, magnesium hydroxide and antimony trioxide are 0.5-1.5 μm respectively; And / or, the smoke suppressant is selected from one or more of molybdenum trioxide and ammonium octamolate.

5. The B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires according to claim 1, characterized in that, The crosslinking agent is selected from one or more of trimethylolpropane trimethacrylate, triallyl isocyanurate, and dicumyl peroxide.

6. The B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires according to claim 1, characterized in that, The antioxidants include primary antioxidants and secondary antioxidants.

7. The B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires according to claim 6, characterized in that, The main antioxidant is a mixture of hindered phenols and copper inhibitors, wherein the hindered phenols are selected from hindered phenols 1010, 1076 or 330; and the copper inhibitor is copper inhibitor 1024. And / or, the auxiliary antioxidant is selected from any one or a mixture of at least two of the following: thioester type DSTP, DLTP and phosphite 168.

8. The B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires according to claim 1, characterized in that, The lubricant is one or both of the following: a polyethylene wax with a molecular weight of 50,000 or greater, or a silicone masterbatch with a siloxane content of not less than 50%. And / or, the processing aid is fluorine-free PPA.

9. A method for preparing a B1-grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for electrical wires as described in any one of claims 1-8, characterized in that, The preparation method includes the following steps: Ethylene-vinyl acetate copolymer A, ethylene-vinyl acetate copolymer B, ethylene propylene diene monomer (EPDM) rubber, and maleic anhydride grafted polyolefin are initially mixed evenly. Then, a mixture of magnesium hydroxide, aluminum hydroxide, antimony trioxide, smoke suppressant, antioxidant, crosslinking aid, lubricant, and processing aid is added. After thorough mixing, the mixture is heated and kneaded, then extruded and granulated by single and twin screw extrusion, dried, and sieved to obtain B1 grade flame-retardant irradiated crosslinked low-smoke halogen-free polyolefin insulation material for electrical wires.

10. The application of the B1-grade flame-retardant irradiated cross-linked low-smoke halogen-free polyolefin insulation material for electrical wires according to any one of claims 1-8 in cables.

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