High flame-retardant low-smoke halogen-free polyolefin cable material and preparation method thereof

Abstract

This application relates to the field of polyolefin cable material technology, specifically disclosing a high flame-retardant, low-smoke, halogen-free polyolefin cable material and its preparation method. The preparation method of a high flame-retardant, low-smoke, halogen-free polyolefin cable material includes the following steps: 1) mixing carrageenan, potassium silicate, divalent metal salt, and water to obtain a gel solution; 2) reacting halogenated cyclodextrin with vinylimidazole to obtain modified cyclodextrin; 3) adding urea, alumina, and iron oxide to the gel solution, then drying, calcining, and grinding to obtain a porous matrix material; 4) co-grinding magnesium hydroxide, aluminum hydroxide, the porous matrix material, and modified cyclodextrin to obtain a hydroxide flame retardant; 5) mixing and extruding ethylene-vinyl acetate copolymer, ethylene propylene diene monomer (EPDM) rubber, metallocene polyethylene, maleic anhydride-grafted polyethylene copolymer, hydroxide flame retardant, and a flame-retardant synergistic carbonizing agent to obtain the final product. The high flame-retardant, low-smoke, halogen-free polyolefin cable material obtained by this application has the advantages of good flame retardant effect and easy processing.

Description

Technical Field

[0001] This application relates to the field of polyolefin cable material technology, and more specifically, it relates to a high flame retardant, low smoke, halogen-free polyolefin cable material and its preparation method. Background Technology

[0002] With the continuous development of society, people's awareness of safety and environmental protection is increasing. Fires caused by aging cables, short circuits, etc., not only cause huge economic losses but also result in casualties. A large proportion of electrical fires are caused by burning cables, and the frequent occurrence of power cable fires has prompted people to explore and develop power cables with higher flame-retardant properties.

[0003] Traditional halogen-containing cables, such as PVC cable materials, produce toxic gases and fumes when burning, causing secondary injuries during a fire. Commonly used halogen-free flame-retardant polyolefin cable materials typically use polyolefin resin as a base material and inorganic flame-retardant materials such as aluminum hydroxide and magnesium hydroxide as flame retardants, produced through blending, internal mixing and plasticizing, and extrusion granulation. Existing halogen-free flame-retardant polyolefin cable materials have three main drawbacks: 1. High amounts of inorganic flame retardants significantly reduce the mechanical properties of the cable material; 2. Adding large amounts of inorganic flame retardants worsens the flowability of the cable material, leading to a sharp increase in screw torque and mains current during extrusion, making extrusion processing difficult; 3. Poor carbonization during combustion, resulting in easy dripping and easy flame spread. These drawbacks are problems that urgently need to be solved.

[0004] In response, technical personnel have proposed several improvement solutions. For example, patent application CN118620318A discloses an irradiated cross-linked flame-retardant polyolefin cable material and its preparation method. The raw material components include resin, modified flame retardant, flame retardant synergist, compatibilizer, antioxidant, cross-linking agent, and lubricant. The modified flame retardant is obtained by loading metal oxides onto modified lignin. By using a modified flame retardant, specifically lignin, its rigid structure is utilized to increase its thermal decomposition temperature. Furthermore, the protective char layer formed during combustion isolates oxygen.

[0005] For example, patent application CN118290839A discloses a nano-modified halogen-free flame-retardant polyolefin cable material. By weight, the cable material is prepared from the following components: polyethylene, ethylene-vinyl acetate copolymer, phosphorus-based flame retardant, nano clay, nano silica, nano alumina, ultrafine brucite powder, antioxidant, and light stabilizer. It uses polyethylene and ethylene-vinyl acetate copolymer as blends, and ultrafine brucite powder replaces the high-cost flame retardants magnesium hydroxide and aluminum hydroxide. The combination of nano silica, nano alumina, and ultrafine brucite powder improves the flame retardant and insulation properties.

[0006] The improvement plan for the aforementioned document can currently only improve the performance of one of the defects, resulting in a weak overall performance improvement for polyolefin cable materials. Summary of the Invention

[0007] To further improve the overall performance of polyolefin cable materials in terms of flame retardancy and processing properties, this application provides a high flame retardant, low-smoke, halogen-free polyolefin cable material and its preparation method.

[0008] In a first aspect, this application provides a method for preparing a high flame-retardant, low-smoke, halogen-free polyolefin cable material, employing the following technical solution:

[0009] A method for preparing a high flame-retardant, low-smoke, halogen-free polyolefin cable material includes the following steps:

[0010] 1) Prepare a gel solution by mixing carrageenan, potassium silicate, divalent metal salt, and water evenly;

[0011] 2) Dissolve the halocyclodextrin in DMF, then add vinylimidazole, and microwave the mixture under inert gas for 3-5 hours. After removing DMF, the modified cyclodextrin is obtained.

[0012] 3) Add urea, aluminum oxide and iron oxide to the gel solution, then add surfactant, purge with nitrogen and homogenize, then freeze dry, pulverize, calcine and grind to obtain porous matrix material;

[0013] 4) A hydroxide flame retardant was prepared by grinding magnesium hydroxide, aluminum hydroxide, porous matrix material, and modified cyclodextrin together.

[0014] 5) Take 52-61 parts of ethylene-vinyl acetate copolymer, 5-10 parts of ethylene propylene diene monomer (EPDM) rubber, 24-30 parts of metallocene polyethylene, 13-16 parts of maleic anhydride grafted polyethylene copolymer, 200-230 parts of hydroxide flame retardant, 12-18 parts of flame retardant synergist carbonizing agent, 2-2.6 parts of antioxidant, 1.5-2.5 parts of processing aid, and 2-3 parts of carbon black, place them in an internal mixer for premixing and internal mixing, and then extrude and pelletize to obtain the final product.

[0015] Preferably, step 1) further includes at least one of the following technical features:

[0016] 11) The mass ratio of carrageenan, potassium silicate, divalent metal salt, and water is (0.1-0.2):(0.15-0.3):(0.05-0.08):1;

[0017] 12) The divalent metal salt is at least one of cobalt sulfate, nickel nitrate, manganese nitrate, copper nitrate, and ferrous sulfate.

[0018] Preferably, step 3) further includes at least one of the following technical features:

[0019] 31) The mass ratio of the gel solution, urea, aluminum oxide, and iron oxide is 1:(0.03-0.05):(0.3-0.5):(0.05-0.1);

[0020] 32) The surfactant is an alkyl quaternary ammonium salt;

[0021] 33) The nitrogen content after homogenization is 5-10%.

[0022] Preferably, the alkyl quaternary ammonium salt is at least one of dodecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide.

[0023] Preferably, in step 4), the mass ratio of magnesium hydroxide, aluminum hydroxide, porous matrix material, and modified cyclodextrin is 1:(0.6-0.8):(0.2-0.35):(0.06-0.075).

[0024] Preferably, in step 3), the average particle size of the porous matrix is ​​50-200 μm.

[0025] Preferably, in step 5), the ethylene-vinyl acetate copolymer is composed of 12-16 parts of EVA with a VA content of 28% and 40-45 parts of EVA with a VA content of 33%.

[0026] Preferably, in step 5), the mixing temperature is 170-175℃.

[0027] Preferably, in step 5), the extrusion includes twin-screw extrusion and single-screw extrusion. The processing temperatures for twin-screw extrusion are: Zone 1 110±5℃, Zone 2 130±5℃, Zone 3 130±5℃, Zone 4 125±5℃, Zone 5 115±5℃, Zone 6 110±5℃, and Zone 7 110±5℃. The processing temperatures for single-screw extrusion are: Zone 1 110±5℃, Zone 2 120±5℃, Zone 3 130±5℃, Zone 4 140±5℃, and Zone 5 140±5℃.

[0028] Secondly, this application provides a high flame-retardant, low-smoke, halogen-free polyolefin cable material, which is prepared by the preparation method described in any one of claims 1-9.

[0029] In summary, this application has the following beneficial effects:

[0030] 1. This application utilizes a halogen-free flame-retardant system formed by the combination of a flame-retardant synergist charring agent and a hydroxide flame retardant to significantly improve the flame-retardant performance of cable materials. Furthermore, the use of a porous matrix to dope magnesium hydroxide and aluminum hydroxide inorganic flame retardants reduces the amount of aluminum hydroxide and magnesium hydroxide required and improves the interfacial properties between hydroxide flame retardants and between hydroxide flame retardants and organic resins, thereby enhancing the processing performance and water resistance of the cable material. In addition, the hydroxide flame retardant in this application combines the advantages of hydroxides—difficult to ignite, low heat release, heat and oxygen insulation, and non-dripping—ensuring that the cable material exhibits properties such as slow spread of fire and rapid self-extinguishing.

[0031] 2. The hydroxide flame retardant of this application is formulated from a porous matrix material compounded with magnesium hydroxide and aluminum hydroxide. The porous matrix material is first constructed into a double gel system, and divalent metal ions are introduced into the system. The metal ions can form stable complexes between the double helix molecular chains of carrageenan and between the molecular chains of potassium silicate. After calcination, the metal ions can form metal sites, which can catalyze the formation of a char layer during the combustion of cable materials, and can also catalyze the conversion of intermediate substances such as carbon monoxide into stable substances, reducing the generation of flammable / toxic gases. In addition, the addition of urea to the double gel system can introduce nitrogen vacancies, thereby increasing the number of metal sites. The porous matrix material of this application can shorten the combustion time and reduce the release of flammable / toxic gases by adsorbing flammable gases. At the same time, the macrocyclic structure and nitrogen-containing groups of modified cyclodextrin can promote char formation, capture free radicals, and exert a synergistic flame retardant effect with the metal sites. Furthermore, the addition of modified cyclodextrin can also improve the compatibility of the hydroxide flame retardant and improve its processing performance.

[0032] 3. This application uses high molecular weight linear polydimethylsiloxane, which reduces the intermolecular cohesive forces within the polymer, thereby improving melt flowability, further enhancing the processing performance of the product, and increasing the surface gloss of the cable material. Attached Figure Description

[0033] Figure 1 This is a SEM image of the porous matrix material of Embodiment 3 of this application.

[0034] Figure 2 This is a TEM image of the porous matrix material of Embodiment 3 of this application.

[0035] Figure 3 This is an EDX analysis diagram of the porous matrix material of Embodiment 3 of this application.

[0036] Figure 4 This is a schematic diagram of the combustion performance test of the high flame retardant, low smoke, halogen-free polyolefin cable material in Embodiment 3 of this application. Detailed Implementation

[0037] The present application will be further described in detail below with reference to the embodiments.

[0038] This application provides a method for preparing high flame-retardant, low-smoke, halogen-free polyolefin cable material, comprising the following steps:

[0039] 1) Prepare a gel solution by mixing carrageenan, potassium silicate, divalent metal salt, and water evenly;

[0040] 2) Dissolve the halocyclodextrin in DMF, then add vinylimidazole, and microwave the mixture under inert gas for 3-5 hours. After removing DMF, the modified cyclodextrin is obtained.

[0041] 3) Add urea, aluminum oxide and iron oxide to the gel solution, then add surfactant, purge with nitrogen and homogenize, then freeze dry, pulverize, calcine and grind to obtain porous matrix material;

[0042] 4) A hydroxide flame retardant was prepared by grinding magnesium hydroxide, aluminum hydroxide, porous matrix material, and modified cyclodextrin together.

[0043] 5) Take 52-61 parts of ethylene-vinyl acetate copolymer, 5-10 parts of ethylene propylene diene monomer (EPDM) rubber, 24-30 parts of metallocene polyethylene, 13-16 parts of maleic anhydride grafted polyethylene copolymer, 200-230 parts of hydroxide flame retardant, 12-18 parts of flame retardant synergist carbonizing agent, 2-2.6 parts of antioxidant, 1.5-2.5 parts of processing aid, and 2-3 parts of carbon black, place them in an internal mixer for premixing and internal mixing, and then extrude and pelletize to obtain the final product.

[0044] Preferably, step 1) further includes at least one of the following technical features:

[0045] 11) The mass ratio of carrageenan, potassium silicate, divalent metal salt, and water is (0.1-0.2):(0.15-0.3):(0.05-0.08):1;

[0046] 12) The divalent metal salt is at least one of zinc sulfate, cobalt sulfate, nickel nitrate, manganese nitrate, copper nitrate, and ferrous sulfate.

[0047] In some specific embodiments, the mass ratio of carrageenan, potassium silicate, divalent metal salt, and water can be 0.1:0.15:0.05:1, 0.2:0.3:0.08:1, 0.1:0.3:0.08:1, 0.1:0.3:0.05:1, 0.1:0.15:0.08:1, 0.2:0.15:0.05:1, 0.2:0.3:0.05:1, 0.2:0.15:0.08:1, 0.15:0.2:0.07:1, 0.15:0.25:0.05:1, 0.15:0.2:0.08:1, or 0.2:0.15:0.075:1.

[0048] In some specific embodiments, the divalent metal salt can be zinc sulfate, cobalt sulfate, nickel nitrate, manganese nitrate, copper nitrate, or ferrous sulfate. More preferably, the divalent metal salt is composed of ferrous sulfate and cobalt sulfate in a mass ratio of 2:1.

[0049] Preferably, step 3) further includes at least one of the following technical features:

[0050] 31) The mass ratio of the gel solution, urea, aluminum oxide, and iron oxide is 1:(0.03-0.05):(0.3-0.5):(0.05-0.1);

[0051] 32) The surfactant is an alkyl quaternary ammonium salt;

[0052] 33) The nitrogen content after homogenization is 5-10%.

[0053] In some specific embodiments, the mass ratio of the gel solution, urea, aluminum oxide, and iron oxide can be 1:0.03:0.3:0.05, 1:0.05:0.5:0.1, 1:0.05:0.3:0.05, 1:0.05:0.5:0.05, 1:0.03:0.5:0.05, 1:0.03:0.5:0.1, 1:0.03:0.5:0.05, 1:0.05:0.3:0.1, or 1:0.035:0.5:0.075.

[0054] In some specific embodiments, the nitrogen content after homogenization can be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0055] Preferably, the alkyl quaternary ammonium salt is at least one of dodecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide.

[0056] Preferably, in step 4), the mass ratio of magnesium hydroxide, aluminum hydroxide, porous matrix material, and modified cyclodextrin is 1:(0.6-0.8):(0.2-0.35):(0.06-0.075).

[0057] In some specific embodiments, in step 4), the mass ratio of magnesium hydroxide, aluminum hydroxide, porous matrix material, and modified cyclodextrin can be 1:0.6:0.2:0.06, 1:0.8:0.35:0.075, 1:0.7:0.3:0.07, 1:0.6:0.2:0.075, 1:0.6:0.35:0.075, 1:0.8:0.2:0.06, 1:0.8:0.35:0.06, 1:0.6:0.35:0.06, 1:0.7:0.2:0.075, 1:0.6:0.3:0.06, or 1:0.7:0.2:0.07.

[0058] Preferably, in step 3), the average particle size of the porous matrix is ​​50-200 μm.

[0059] Preferably, in step 5), the ethylene-vinyl acetate copolymer is composed of 12-16 parts of EVA with a VA content of 28% and 40-45 parts of EVA with a VA content of 33%.

[0060] Preferably, in step 5), the mixing temperature is 170-175℃.

[0061] Preferably, in step 5), the extrusion includes twin-screw extrusion and single-screw extrusion. The processing temperatures for twin-screw extrusion are: Zone 1 110±5℃, Zone 2 130±5℃, Zone 3 130±5℃, Zone 4 125±5℃, Zone 5 115±5℃, Zone 6 110±5℃, and Zone 7 110±5℃. The processing temperatures for single-screw extrusion are: Zone 1 110±5℃, Zone 2 120±5℃, Zone 3 130±5℃, Zone 4 140±5℃, and Zone 5 140±5℃.

[0062] Preferably, the antioxidant is composed of antioxidant A, antioxidant B and antioxidant C. Antioxidant A is the main antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], antioxidant B is dodecayl thiodipropionate, and antioxidant C is 2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0063] Preferably, the flame-retardant synergistic carbon-forming agent is nano-montmorillonite or sepiolite.

[0064] Preferably, the processing aid is a silane coupling agent.

[0065] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available. Example 1

[0066] The preparation method of the high flame-retardant, low-smoke, halogen-free polyolefin cable material in this embodiment includes the following steps:

[0067] 1) Accurately weigh 100g carrageenan, 300g potassium silicate, 50g divalent metal salt and 1kg water and add them to a 2L beaker. Mix them evenly with a stirring speed of 500rpm and degas to obtain a gel solution.

[0068] 2) Dissolve 80g of halocyclodextrin in 500ml of DMF, then add 25g of vinylimidazole, and microwave the mixture for 3h under inert gas. After removing DMF, the modified cyclodextrin is obtained.

[0069] 3) Add 1 kg of gel solution to the stirred tank, then add 30 g of urea, 300 g of alumina and 100 g of iron oxide, then add 20 g of surfactant, and homogenize after passing nitrogen gas through it. The nitrogen content after homogenization is 5%. Then freeze dry, pulverize and place in a calcining furnace to calcine at 750°C for 3 hours. Grind to obtain porous matrix material.

[0070] 4) Weigh 1 kg of magnesium hydroxide, 800 g of aluminum hydroxide, 200 g of porous matrix material, and 60 g of modified cyclodextrin, grind them together to obtain a hydroxide flame retardant;

[0071] 5) Take 54 kg of ethylene-vinyl acetate copolymer, 6 kg of EPDM rubber, 25 kg of metallocene polyethylene, 14 kg of maleic anhydride grafted polyethylene copolymer, 210 kg of hydroxide flame retardant, 8 kg of flame retardant synergist carbonizing agent, 2.2 kg of antioxidant, 2.5 kg of processing aid, and 2 kg of carbon black and premix them in a mixer. Then, mix them in a mixer at 170-175℃ for 14 minutes to ensure that the mixed material is soft and thoroughly cooked with no powder spots on the surface. Then, add the mixed material to a double cone feeder through a hopper. The material is kneaded and then sequentially extruded through twin-screw extrusion, single-screw extrusion, die pelletizing, and air-cooled conveying to obtain high flame-retardant, low-smoke, halogen-free polyolefin cable material. The processing temperatures for twin-screw extrusion are: Zone 1 110±5℃, Zone 2 130±5℃, Zone 3 130±5℃, Zone 4 125±5℃, Zone 5 115±5℃, Zone 6 110±5℃, and Zone 7 110±5℃. The processing temperatures for single-screw extrusion are: Zone 1 110±5℃, Zone 2 120±5℃, Zone 3 130±5℃, Zone 4 140±5℃, and Zone 5 140±5℃.

[0072] The divalent metal salt is cobalt sulfate. The halocyclodextrin is brominated cyclodextrin. The surfactant is dodecyltrimethylammonium bromide. The average particle size of the porous matrix is ​​200 μm. The average particle size (D50) of aluminum hydroxide is 1.7-2.3 μm, and the specific gravity is 2.3-2.4 g / cm³. 3 The average particle size (D50) of magnesium hydroxide is 1.5-2.5 μm, and its specific gravity is 2.3-2.4 g / cm³. 3The processing aid is polydimethylsiloxane. The antioxidant consists of 0.8 kg of antioxidant A, 0.6 kg of antioxidant B, and 0.8 kg of antioxidant C. The flame retardant synergist and char-forming agent is nano-montmorillonite. The ethylene-vinyl acetate copolymer consists of 14 kg of EVA with a VA content of 28% and 40 kg of EVA with a VA content of 33%. The ethylene propylene diene monomer (EPDM) rubber is from Exxon Mobil, with a melt index of 0.1-0.4 g / 10 min determined by the GB / T3682-2000 method, a tensile strength of 12-16 MPa determined by the GB1040 method, and an elongation at break of 550-700%. Maleic anhydride-grafted polyolefin elastomer copolymer, with a grafting rate of 0.5-1.0%, a melt index of 0.5-1.5 g / 10 min as determined by GB / T3682-2000, a tensile strength of 20-24 MPa, and an elongation at break of 700-950%. Example 2

[0073] The preparation method of the high flame-retardant, low-smoke, halogen-free polyolefin cable material in this embodiment includes the following steps:

[0074] 1) Accurately weigh 200g carrageenan, 150g potassium silicate, 80g divalent metal salt and 1kg water and add them to a 2L beaker. Mix them evenly with a stirring speed of 500rpm and degas to obtain a gel solution.

[0075] 2) Dissolve 80g of halocyclodextrin in 500ml of DMF, then add 25g of vinylimidazole, and microwave the mixture for 3h under inert gas. After removing DMF, the modified cyclodextrin is obtained.

[0076] 3) Add 1 kg of gel solution to the stirred tank, then add 50 g of urea, 500 g of alumina and 50 g of iron oxide, then add 20 g of surfactant, and homogenize after passing nitrogen gas through it. The nitrogen content after homogenization is 10%. Then freeze dry, pulverize and place in a calcining furnace to calcine at 750°C for 3 hours. Grind to obtain porous matrix material.

[0077] 4) Weigh 1 kg of magnesium hydroxide, 600 g of aluminum hydroxide, 350 g of porous matrix material, and 75 g of modified cyclodextrin, grind them together to obtain a hydroxide flame retardant;

[0078] 5) Take 54 kg of ethylene-vinyl acetate copolymer, 6 kg of EPDM rubber, 25 kg of metallocene polyethylene, 14 kg of maleic anhydride grafted polyethylene copolymer, 210 kg of hydroxide flame retardant, 8 kg of flame retardant synergist carbonizing agent, 2.2 kg of antioxidant, 2.5 kg of processing aid, and 2 kg of carbon black and premix them in a mixer. Then, mix them in a mixer at 170-175℃ for 14 minutes to ensure that the mixed material is soft and thoroughly cooked with no powder spots on the surface. Then, add the mixed material to a double cone feeder through a hopper. The material is kneaded and then sequentially extruded through twin-screw extrusion, single-screw extrusion, die pelletizing, and air-cooled conveying to obtain high flame-retardant, low-smoke, halogen-free polyolefin cable material. The processing temperatures for twin-screw extrusion are: Zone 1 110±5℃, Zone 2 130±5℃, Zone 3 130±5℃, Zone 4 125±5℃, Zone 5 115±5℃, Zone 6 110±5℃, and Zone 7 110±5℃. The processing temperatures for single-screw extrusion are: Zone 1 110±5℃, Zone 2 120±5℃, Zone 3 130±5℃, Zone 4 140±5℃, and Zone 5 140±5℃.

[0079] The divalent metal salt is nickel sulfate. The halocyclodextrin is chlorocyclodextrin. The surfactant is hexadecyltrimethylammonium bromide. The average particle size of the porous matrix is ​​50 μm. The average particle size (D50) of aluminum hydroxide is 1.7-2.3 μm, and the specific gravity is 2.3-2.4 g / cm³. 3 The average particle size (D50) of magnesium hydroxide is 1.5-2.5 μm, and its specific gravity is 2.3-2.4 g / cm³. 3 The processing aid is polydimethylsiloxane. The antioxidant consists of 0.8 kg of antioxidant A, 0.6 kg of antioxidant B, and 0.8 kg of antioxidant C. The flame retardant synergist and char-forming agent is nano-montmorillonite. The ethylene-vinyl acetate copolymer consists of 14 kg of EVA with a VA content of 28% and 40 kg of EVA with a VA content of 33%. The ethylene propylene diene monomer (EPDM) rubber is from Exxon Mobil, with a melt index of 0.1-0.4 g / 10 min determined by the GB / T3682-2000 method, a tensile strength of 12-16 MPa determined by the GB1040 method, and an elongation at break of 550-700%. Maleic anhydride-grafted polyolefin elastomer copolymer, with a grafting rate of 0.5-1.0%, a melt index of 0.5-1.5 g / 10 min as determined by GB / T3682-2000, a tensile strength of 20-24 MPa, and an elongation at break of 700-950%. Example 3

[0080] The preparation method of the high flame-retardant, low-smoke, halogen-free polyolefin cable material in this embodiment includes the following steps:

[0081] 1) Accurately weigh 150g carrageenan, 200g potassium silicate, 60g divalent metal salt and 1kg water and add them to a 2L beaker. Mix them evenly with a stirring speed of 500rpm and degas to obtain a gel solution.

[0082] 2) Dissolve 80g of halocyclodextrin in 500ml of DMF, then add 25g of vinylimidazole, and microwave the mixture for 3h under inert gas. After removing DMF, the modified cyclodextrin is obtained.

[0083] 3) Add 1 kg of gel solution to the stirred tank, then add 40 g of urea, 350 g of alumina and 60 g of iron oxide, then add 20 g of surfactant, and homogenize after passing nitrogen gas through it. The nitrogen content after homogenization is 8.5%. Then freeze dry, pulverize and place in a calcining furnace to calcine at 750°C for 3 hours. Grind to obtain porous matrix material.

[0084] 4) Weigh 1 kg of magnesium hydroxide, 800 g of aluminum hydroxide, 300 g of porous matrix material, and 70 g of modified cyclodextrin, grind them together to obtain a hydroxide flame retardant;

[0085] 5) Take 54 kg of ethylene-vinyl acetate copolymer, 6 kg of EPDM rubber, 25 kg of metallocene polyethylene, 14 kg of maleic anhydride grafted polyethylene copolymer, 210 kg of hydroxide flame retardant, 8 kg of flame retardant synergist carbonizing agent, 2.2 kg of antioxidant, 2.5 kg of processing aid, and 2 kg of carbon black and premix them in a mixer. Then, mix them in a mixer at 170-175℃ for 14 minutes to ensure that the mixed material is soft and thoroughly cooked with no powder spots on the surface. Then, add the mixed material to a double cone feeder through a hopper. The material is kneaded and then sequentially extruded through twin-screw extrusion, single-screw extrusion, die pelletizing, and air-cooled conveying to obtain high flame-retardant, low-smoke, halogen-free polyolefin cable material. The processing temperatures for twin-screw extrusion are: Zone 1 110±5℃, Zone 2 130±5℃, Zone 3 130±5℃, Zone 4 125±5℃, Zone 5 115±5℃, Zone 6 110±5℃, and Zone 7 110±5℃. The processing temperatures for single-screw extrusion are: Zone 1 110±5℃, Zone 2 120±5℃, Zone 3 130±5℃, Zone 4 140±5℃, and Zone 5 140±5℃.

[0086] The divalent metal salt is composed of ferrous sulfate and cobalt sulfate in a mass ratio of 2:1. The halogenated cyclodextrin is chlorocyclodextrin. The surfactant is hexadecyltrimethylammonium bromide. The average particle size of the porous matrix is ​​100 μm. The average particle size (D50) of aluminum hydroxide is 1.7-2.3 μm, and the specific gravity is 2.3-2.4 g / cm³. 3 The average particle size (D50) of magnesium hydroxide is 1.5-2.5 μm, and its specific gravity is 2.3-2.4 g / cm³. 3The processing aid is polydimethylsiloxane. The antioxidant consists of 0.8 kg of antioxidant A, 0.6 kg of antioxidant B, and 0.8 kg of antioxidant C. The flame retardant synergist and char-forming agent is nano-montmorillonite. The ethylene-vinyl acetate copolymer consists of 14 kg of EVA with a VA content of 28% and 40 kg of EVA with a VA content of 33%. The ethylene propylene diene monomer (EPDM) rubber is from Exxon Mobil, with a melt index of 0.1-0.4 g / 10 min determined by the GB / T3682-2000 method, a tensile strength of 12-16 MPa determined by the GB1040 method, and an elongation at break of 550-700%. Maleic anhydride-grafted polyolefin elastomer copolymer, with a grafting rate of 0.5-1.0%, a melt index of 0.5-1.5 g / 10 min as determined by GB / T3682-2000, a tensile strength of 20-24 MPa, and an elongation at break of 700-950%.

[0087] Comparative Example 1

[0088] The preparation method of the high flame-retardant, low-smoke, halogen-free polyolefin cable material in this comparative example includes the following steps: 54 kg of ethylene-vinyl acetate copolymer, 6 kg of ethylene propylene diene monomer (EPDM) rubber, 25 kg of metallocene polyethylene, 14 kg of maleic anhydride-grafted polyethylene copolymer, 210 kg of hydroxide flame retardant, 8 kg of flame-retardant synergistic carbon-forming agent, 2.2 kg of antioxidant, 2.5 kg of processing aid, and 2 kg of carbon black are placed in a mixer for premixing, and then the mixture is internally mixed at 170-175℃ for 14 minutes to ensure that the mixed material is soft, thoroughly cooked, and free of powdery particles on the surface; then the mixing... The good material clumps are fed into the double-cone feed hopper through the lifting hopper and kneaded, and then successively passed through twin-screw extrusion, single-screw extrusion, die pelletizing, and air-cooled conveying to obtain high flame-retardant, low-smoke, halogen-free polyolefin cable material. The processing temperatures of twin-screw extrusion are: Zone 1 110±5℃, Zone 2 130±5℃, Zone 3 130±5℃, Zone 4 125±5℃, Zone 5 115±5℃, Zone 6 110±5℃, and Zone 7 110±5℃. The processing temperatures of single-screw extrusion are: Zone 1 110±5℃, Zone 2 120±5℃, Zone 3 130±5℃, Zone 4 140±5℃, and Zone 5 140±5℃.

[0089] The hydroxide flame retardant consists of 60 kg of aluminum hydroxide and 150 kg of magnesium hydroxide. The average particle size (D50) of aluminum hydroxide is 1.7-2.3 μm, and its specific gravity is 2.3-2.4 g / cm³. 3 The average particle size (D50) of magnesium hydroxide is 1.5-2.5 μm, and its specific gravity is 2.3-2.4 g / cm³. 3The processing aid is polydimethylsiloxane. The antioxidant consists of 0.8 kg of antioxidant A, 0.6 kg of antioxidant B, and 0.8 kg of antioxidant C. The flame retardant synergist and char-forming agent is nano-montmorillonite. The ethylene-vinyl acetate copolymer consists of 14 kg of EVA with a VA content of 28% and 40 kg of EVA with a VA content of 33%. The ethylene propylene diene monomer (EPDM) rubber is from Exxon Mobil, with a melt index of 0.1-0.4 g / 10 min determined by the GB / T3682-2000 method, a tensile strength of 12-16 MPa determined by the GB1040 method, and an elongation at break of 550-700%. Maleic anhydride-grafted polyolefin elastomer copolymer, with a grafting rate of 0.5-1.0%, a melt index of 0.5-1.5 g / 10 min as determined by GB / T3682-2000, a tensile strength of 20-24 MPa, and an elongation at break of 700-950%.

[0090] Comparative Example 2

[0091] The preparation method of the high flame-retardant, low-smoke, halogen-free polyolefin cable material in this comparative example includes the following steps:

[0092] 1) Dissolve 80g of halocyclodextrin in 500ml of DMF, then add 25g of vinylimidazole, and microwave the mixture for 3h under inert gas. After removing DMF, the modified cyclodextrin is obtained.

[0093] 2) Weigh 100 kg of magnesium hydroxide, 100 kg of aluminum hydroxide, and 6 kg of modified cyclodextrin, grind them together, and then prepare the hydroxide flame retardant;

[0094] 3) Take 54 kg of ethylene-vinyl acetate copolymer, 6 kg of EPDM rubber, 25 kg of metallocene polyethylene, 14 kg of maleic anhydride grafted polyethylene copolymer, 210 kg of hydroxide flame retardant, 8 kg of flame retardant synergist carbonizing agent, 2.2 kg of antioxidant, 2.5 kg of processing aid, and 2 kg of carbon black and premix them in a mixer. Then, mix them in a mixer at 170-175℃ for 14 minutes to ensure that the mixed material is soft and thoroughly cooked with no powder spots on the surface. Then, add the mixed material to a double cone feeder through a hopper. The material is kneaded and then sequentially extruded through twin-screw extrusion, single-screw extrusion, die pelletizing, and air-cooled conveying to obtain high flame-retardant, low-smoke, halogen-free polyolefin cable material. The processing temperatures for twin-screw extrusion are: Zone 1 110±5℃, Zone 2 130±5℃, Zone 3 130±5℃, Zone 4 125±5℃, Zone 5 115±5℃, Zone 6 110±5℃, and Zone 7 110±5℃. The processing temperatures for single-screw extrusion are: Zone 1 110±5℃, Zone 2 120±5℃, Zone 3 130±5℃, Zone 4 140±5℃, and Zone 5 140±5℃.

[0095] Among them, the halogenated cyclodextrin is a brominated cyclodextrin. The average particle size (D50) of aluminum hydroxide is 1.7-2.3 μm, and the specific gravity is 2.3-2.4 g / cm³. 3 The average particle size (D50) of magnesium hydroxide is 1.5-2.5 μm, and its specific gravity is 2.3-2.4 g / cm³. 3 The processing aid is polydimethylsiloxane. The antioxidant consists of 0.8 kg of antioxidant A, 0.6 kg of antioxidant B, and 0.8 kg of antioxidant C. The flame retardant synergist and char-forming agent is nano-montmorillonite. The ethylene-vinyl acetate copolymer consists of 14 kg of EVA with a VA content of 28% and 40 kg of EVA with a VA content of 33%. The ethylene propylene diene monomer (EPDM) rubber is from Exxon Mobil, with a melt index of 0.1-0.4 g / 10 min determined by the GB / T3682-2000 method, a tensile strength of 12-16 MPa determined by the GB1040 method, and an elongation at break of 550-700%. Maleic anhydride-grafted polyolefin elastomer copolymer, with a grafting rate of 0.5-1.0%, a melt index of 0.5-1.5 g / 10 min as determined by GB / T3682-2000, a tensile strength of 20-24 MPa, and an elongation at break of 700-950%.

[0096] Performance testing

[0097] The high flame-retardant, low-smoke, halogen-free polyolefin cable materials of Examples 1-3 and Comparative Examples 1-2 were subjected to relevant performance tests. The technical indicators and typical values ​​(Example 3) are shown in Table 1. The cabling technology preparation and typical values ​​(Example 3) are shown in Table 2. The performance test results of the high flame-retardant, low-smoke, halogen-free polyolefin cable materials of Examples 1-3 and Comparative Examples 1-2 are shown in Table 3. The cabling performance test results of the high flame-retardant, low-smoke, halogen-free polyolefin cable materials of Examples 1-3 and Comparative Examples 1-2 are shown in Table 4.

[0098] Table 1. Technical Specifications and Typical Values ​​of High Flame Retardant, Low Smoke, Halogen-Free Polyolefin Cable Materials

[0099]

[0100] Table 2. Technical Specifications and Typical Values ​​of High Flame Retardant, Low Smoke, Halogen-Free Polyolefin Cable Material for Cable Assembly

[0101]

[0102] Table 3 Performance test results of high flame-retardant, low-smoke, halogen-free polyolefin cable materials in Examples 1-3 and Comparative Examples 1-2

[0103]

[0104] Table 4. Test results of cabling performance of high flame-retardant, low-smoke, halogen-free polyolefin cable materials in Examples 1-3 and Comparative Examples 1-2

[0105]

[0106] The porous substrate from Example 3 was subjected to scanning electron microscopy (SEM) testing, and the results are as follows: Figure 1 As shown; the porous substrate of Example 3 was subjected to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) tests, and the test results are as follows. Figure 2 As shown. Energy dispersive X-ray spectroscopy (EDX) was used to analyze the porous matrix material of Example 3. The analysis results are as follows. Figure 3 As shown, zinc and cobalt atoms in the porous matrix form effective metal sites.

[0107] The high flame-retardant, low-smoke, halogen-free polyolefin cable material from Example 3 was used for cable combustion performance testing. The test results are as follows: Figure 3 As shown.

[0108] Analyze Examples 1-3 and Comparative Examples 1-2, and refer to Tables 1-4. Figure 1-3 It can be seen that the high flame retardant, low smoke, halogen-free polyolefin cable material of this application has very good processing performance and flame retardant performance.

[0109] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a high flame-retardant, low-smoke, halogen-free polyolefin cable material, characterized in that, Includes the following steps: 1) Prepare a gel solution by mixing carrageenan, potassium silicate, a divalent metal salt, and water evenly. The divalent metal salt is composed of ferrous sulfate and cobalt sulfate in a mass ratio of 2:

1. The mass ratio of carrageenan, potassium silicate, divalent metal salt, and water is (0.1-0.2):(0.15-0.3):(0.05-0.08):1; 2) Dissolve the halocyclodextrin in DMF, then add vinylimidazole, and microwave the mixture under inert gas for 3-5 hours. After removing DMF, the modified cyclodextrin is obtained. 3) Urea, alumina, and iron oxide are added to the gel solution, followed by the addition of a surfactant. After homogenization by purging with nitrogen, the solution is freeze-dried, pulverized, calcined, and ground to obtain a porous matrix. The surfactant is an alkyl quaternary ammonium salt. The nitrogen content after homogenization is 5-10%, the calcination temperature is 750℃, and the calcination time is 3 hours. The mass ratio of the gel solution, urea, aluminum oxide, and iron oxide is 1:(0.03-0.05):(0.3-0.5):(0.05-0.1). 4) A hydroxide flame retardant is prepared by grinding magnesium hydroxide, aluminum hydroxide, porous matrix material, and modified cyclodextrin in a mass ratio of 1:(0.6-0.8):(0.2-0.35):(0.06-0.075). The average particle size of the magnesium hydroxide is 1.5-2.5 μm, and the average particle size of the aluminum hydroxide is 1.7-2.3 μm. 5) Take 52-61 parts of ethylene-vinyl acetate copolymer, 5-10 parts of ethylene propylene diene monomer (EPDM) rubber, 24-30 parts of metallocene polyethylene, 13-16 parts of maleic anhydride grafted polyethylene copolymer, 200-230 parts of hydroxide flame retardant, 12-18 parts of flame retardant synergist and carbonizing agent, 2-2.6 parts of antioxidant, 1.5-2.5 parts of processing aid, and 2-3 parts of carbon black, place them in an internal mixer for premixing and internal mixing, and then extrude and pelletize to obtain the final product. The antioxidant is composed of antioxidant A, antioxidant B and antioxidant C, wherein antioxidant A is the main antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], antioxidant B is dodecanol thiodipropionate, antioxidant C is 2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and the flame retardant synergist is nano-montmorillonite or sepiolite.

2. The method for preparing a high flame-retardant, low-smoke, halogen-free polyolefin cable material according to claim 1, characterized in that, The alkyl quaternary ammonium salt is at least one of dodecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide.

3. The method for preparing a high flame-retardant, low-smoke, halogen-free polyolefin cable material according to claim 1, characterized in that, In step 3), the average particle size of the porous matrix is ​​50-200 μm.

4. The method for preparing a high flame-retardant, low-smoke, halogen-free polyolefin cable material according to claim 1, characterized in that, In step 5), the ethylene-vinyl acetate copolymer is composed of 12-16 parts of EVA with a VA content of 28% and 40-45 parts of EVA with a VA content of 33%.

5. The method for preparing a high flame-retardant, low-smoke, halogen-free polyolefin cable material according to claim 1, characterized in that, In step 5), the mixing temperature is 170-175℃.

6. The method for preparing a high flame-retardant, low-smoke, halogen-free polyolefin cable material according to claim 1, characterized in that, In step 5), extrusion includes twin-screw extrusion and single-screw extrusion. The processing temperatures for twin-screw extrusion are: Zone 1 110±5℃, Zone 2 130±5℃, Zone 3 130±5℃, Zone 4 125±5℃, Zone 5 115±5℃, Zone 6 110±5℃, and Zone 7 110±5℃. The processing temperatures for single-screw extrusion are: Zone 1 110±5℃, Zone 2 120±5℃, Zone 3 130±5℃, Zone 4 140±5℃, and Zone 5 140±5℃.

7. A high flame-retardant, low-smoke, halogen-free polyolefin cable material, prepared by the preparation method described in any one of claims 1-6.

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