N-methylmaleimide modified sepiolite as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of flame-retardant materials, and particularly relates to N-methylmaleimide modified sepiolite as well as a preparation method and application thereof. The sepiolite raw material is subjected to acidification pretreatment, silane coupling agent modification and N-methylmaleimide modification, so that the dispersity of sepiolite in the flame-retardant cable material can be remarkably improved, the flame retardance of the flame-retardant cable material is effectively improved, and meanwhile, the flame-retardant cable material keeps good tensile strength, elongation at break and volume resistivity; the cable has a good application prospect in the field of communication cables or power cables.

Description

Technical Field

[0001] This invention belongs to the technical field of flame retardant materials, specifically relating to an N-methylmaleimide-modified sepiolite, its preparation method, and its application. Background Technology

[0002] Electric wires and cables are widely used in numerous fields such as power, communications, industry, and construction. Currently, the insulation and sheathing materials of electric wires and cables are mostly made of high molecular polymers such as polyethylene and polyvinyl chloride. However, these materials are highly flammable and pose a certain fire hazard. Therefore, developing a flame-retardant material that meets fire safety standards (such as UL94, IEC 60332) and environmental protection requirements (such as halogen-free) is the current trend in the industry.

[0003] Currently, commonly used flame retardant materials include halogenated flame retardants, inorganic flame retardants, and phosphorus-based or nitrogen-based flame retardants. Although halogenated flame retardants have high flame retardant efficiency, they release harmful gases (such as dioxins) when burning. Inorganic flame retardants (such as aluminum hydroxide and magnesium hydroxide) can affect the mechanical properties of materials. Phosphorus-based or nitrogen-based flame retardants may migrate and precipitate, resulting in poor long-term stability of the materials.

[0004] Sepiolite is a natural fibrous silicate clay mineral. Due to its high specific surface area, porous structure, and adsorption properties, it is considered a flame-retardant enhancement carrier. However, natural sepiolite has poor compatibility with polymer matrices, is prone to agglomeration, and its flame-retardant mechanism is singular, mainly relying on physical barrier effects, resulting in limited flame-retardant efficiency. Current research on sepiolite modification mostly focuses on modification with silane coupling agents. Although this method can improve the dispersibility of sepiolite in the system, the improvement effect is relatively singular, leading to poor overall performance of the prepared flame-retardant cable materials. Summary of the Invention

[0005] In a first aspect, the present invention provides a method for preparing N-methylmaleimide-modified sepiolite, comprising the following steps:

[0006] (1) The sepiolite raw material is subjected to acid pretreatment to obtain acid pretreated sepiolite;

[0007] (2) Add the acidified pretreated sepiolite to the silane coupling agent solution, stir and heat, and after the reaction, obtain silane coupling agent modified sepiolite; the silane coupling agent includes at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and 3-mercaptopropylmethyldimethoxysilane.

[0008] (3) The silane coupling agent modified sepiolite is mixed and stirred with N-methylmaleimide solution to obtain the N-methylmaleimide modified sepiolite; the mass ratio of the silane coupling agent modified sepiolite to N-methylmaleimide is 10:(1.5-2.5).

[0009] The inventors discovered that acidification pretreatment of sepiolite raw materials can effectively increase the specific surface area, porosity, and pore volume of sepiolite, thereby improving the flame-retardant performance of flame-retardant cable materials. Further modification of the acid-pretreated sepiolite using silane coupling agents can effectively enhance the flame-retardant performance of the cable materials. However, not all silane coupling agents can react well with acid-pretreated sepiolite to obtain high-performance modified sepiolite. N-methylmaleimide can undergo a self-crosslinking reaction at high temperatures to form a dense char layer, enhancing the flame retardancy of the condensed phase. Its nitrogen-containing structure can release inert gases, such as N2, diluting combustible gases and achieving a gas-phase flame-retardant effect. Grafting N-methylmaleimide onto the surface of sepiolite through a chemical reaction not only improves the dispersibility of sepiolite but also makes it easier for sepiolite to form a continuous and stable char layer during combustion, blocking heat and oxygen transfer, thereby improving its chemical flame-retardant performance and solving the problem of poor flame-retardant effects of traditional flame retardants. Modifying sepiolite with acidification, silane coupling agents, and N-methylmaleimide can significantly improve the compatibility of sepiolite with the polymer matrix, thereby improving the dispersibility of sepiolite in flame-retardant cable materials, enhancing the flame-retardant performance of the materials, and ensuring that the materials maintain good tensile strength, elongation at break, and volume resistivity.

[0010] In some embodiments, step (1) of the acidification pretreatment includes adding sepiolite raw material to an acidic reagent and stirring. In some embodiments, the stirring temperature is 60-80°C, and the stirring time is 2-4 hours. In some embodiments, the acidic reagent includes at least one of hydrochloric acid and nitric acid; the concentration of the acidic reagent is 1-5 mol / L, and the mass ratio of the sepiolite raw material to the acidic reagent is 1:(5-15). In some embodiments, after stirring the sepiolite raw material with the acidic reagent, it is subjected to centrifugation, washing, drying, and baking treatment; the drying temperature is 100-130°C, the drying time is 12-24 hours, and the baking temperature is 150-250°C, the baking time is 2-4 hours.

[0011] In some embodiments, the mass ratio of the sepiolite raw material to the silane coupling agent is (10-20):1.

[0012] In some embodiments, in step (2), the solvent of the silane coupling agent solution is a mixed solution of ethanol and water, wherein the volume ratio of ethanol to water is (5-10):1.

[0013] In some embodiments, in step (2), the heating temperature is 40-60°C, and the reaction time is 6-8 hours. In some embodiments, in step (2), the reaction is followed by filtration, washing, and vacuum drying; the washing reagent is ethanol, the vacuum drying temperature is 50-60°C, and the vacuum drying time is 12-24 hours.

[0014] In some embodiments, in step (3), the concentration of the N-methylmaleimide solution is 50-100 g / L, and the solvent of the solution includes at least one of N,N-dimethyldiamide and dimethyl sulfoxide; the stirring temperature is 25-40°C, and the stirring time is 8-16 h. In some embodiments, in step (3), after stirring, washing and vacuum drying are performed; the washing reagent is ethanol, the vacuum drying temperature is 50-60°C, and the vacuum drying time is 12-24 h.

[0015] In a second aspect, the present invention provides an N-methylmaleimide-modified sepiolite prepared by the above method.

[0016] In a third aspect, this invention provides a flame-retardant cable material, comprising, by weight, 20-45 parts of a polymer matrix, 41-65 parts of a flame-retardant filler, 1-5 parts of the aforementioned N-methylmaleimide-modified sepiolite, 1-3 parts of an antioxidant, and 0.5-2 parts of a lubricant; the flame-retardant filler comprises 15-25 parts of aluminum hydroxide, 25-35 parts of magnesium hydroxide, and 1-5 parts of red phosphorus. The inventors have discovered that specific flame-retardant fillers can be combined with the N-methylmaleimide-modified sepiolite of this invention to achieve superior performance in the flame-retardant cable material.

[0017] In some embodiments, the polymer matrix comprises 5-10 parts polyethylene, 10-20 parts ethylene and its copolymers, and 5-15 parts polyolefin elastomer. In some preferred embodiments, the polyethylene comprises at least one of low-density polyethylene, linear low-density polyethylene, high-density polyethylene, and metallocene polyethylene. In some preferred embodiments, the ethylene and its copolymers comprise at least one of ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer. In some preferred embodiments, the polyolefin elastomer comprises at least one of ethylene-α-olefin copolymer, propylene-α-olefin copolymer, and 1-butene polymer.

[0018] In some embodiments, the antioxidant includes at least one selected from 2,6-di-tert-butyl-p-cresol, pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N-isopropyl-N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, tris(2,4-di-tert-butylphenyl) phosphite, dilauryl thiodipropionate, and distearate thiodipropionate.

[0019] In some embodiments, the lubricant includes at least one of stearic acid, glyceryl stearate, zinc stearate, polyethylene wax, ethylene bis-stearamide, and polydimethoxysilane.

[0020] In a fourth aspect, the present invention provides a method for preparing the above-mentioned flame-retardant cable material, comprising the following steps: adding each raw material to a mixer for mixing to obtain a compound; and feeding the compound to a twin-screw extruder to obtain the flame-retardant cable material.

[0021] In some preferred embodiments, the preparation method of the above-mentioned flame-retardant cable material specifically includes the following steps:

[0022] S1. Add the polymer matrix, antioxidant, and lubricant to the internal mixer and mix for 1-10 minutes.

[0023] S2. Add flame-retardant filler to a mixer and mix for 1-10 minutes. Then add N-methylmaleimide modified sepiolite to the mixer and mix for 1-10 minutes to obtain the mixture.

[0024] S3. The mixture obtained in step S2 is fed into a twin-screw extruder to obtain flame-retardant cable material.

[0025] In some preferred embodiments, in step S1, the internal mixer temperature is maintained at 140-170℃ and the rotation speed is 70-100 rpm / min before feeding; in step S2, the internal mixer temperature is maintained at 140-170℃ and the rotation speed is 100-120 rpm / min before feeding; in step S3, the temperatures of each temperature range in the twin-screw extruder are maintained at 120-140℃, 150-170℃, 160-180℃, and 170-190℃ respectively before feeding, and the screw rotation speed is 200-400 rpm / min.

[0026] In a fifth aspect, the present invention provides the application of the above-mentioned flame-retardant cable material in the preparation of communication cables or power cables.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) By using acidification, silane coupling agent and N-methylmaleimide to modify sepiolite, not only can the dispersibility of sepiolite be effectively improved, but also a dense carbon layer can be formed and gas phase flame retardant can be achieved by taking advantage of the self-crosslinking reaction of N-methylmaleimide at high temperature, giving sepiolite better flame retardant performance and solving the problem of poor flame retardant effect of traditional flame retardants.

[0029] (2) The flame-retardant cable material prepared by using N-methylmaleimide modified sepiolite provided by the present invention not only has excellent flame-retardant properties, but also has good tensile strength, elongation at break and volume resistivity, and has good application prospects in the field of communication cables or power cables. Attached Figure Description

[0030] Figure 1 Infrared spectra of sepiolite raw material, N-methylmaleimide, and N-methylmaleimide-modified sepiolite prepared in Example 1. Detailed Implementation

[0031] The following detailed embodiments further illustrate the content of the present invention. These embodiments do not constitute a limitation on the scope of protection of the present invention. Non-essential modifications and adjustments made by others based on the concept of the present invention still fall within the scope of protection of the present invention. The raw materials, reagents, or devices used in the embodiments are all available from conventional commercial sources or can be obtained through existing technical methods. Unless otherwise specified, the experimental or testing methods are conventional methods in the art.

[0032] The sources of raw materials used in this embodiment and comparative example are shown in Table 1.

[0033] Table 1

[0034]

[0035]

[0036] Example 1

[0037] The N-methylmaleimide-modified sepiolite of this embodiment is prepared through the following steps:

[0038] (1) Disperse 20g of sepiolite raw material in 200g of dilute hydrochloric acid (1mol / L), stir at 60℃ for 4h, centrifuge and wash until neutral, dry at 100℃ for 16h, and then place the dried sepiolite in an oven and bake at 200℃ for 4h to obtain acid-pretreated sepiolite.

[0039] (2) Dissolve 2g of 3-mercaptopropyltrimethoxysilane in a mixed solvent of 45mL ethanol and 5mL water, adjust the pH of the solution to 4-5 with acetic acid, and then stir at 25℃ for 2h to obtain a solution containing mercaptosilane coupling agent; add the acidified sepiolite to the solution containing mercaptosilane coupling agent, stir and heat to 60℃ under reflux conditions, react for 8h, and pass nitrogen gas during the reaction. After the reaction is completed, filter and wash three times with ethanol to remove unreacted mercaptosilane coupling agent. After washing, vacuum dry at 60℃ for 12h to obtain sepiolite modified with mercaptosilane coupling agent;

[0040] (3) Dissolve 5g of N-methylmaleimide in 50mL of dimethyl sulfoxide at room temperature to obtain an N-methylmaleimide solution; take 10g of sepiolite modified with mercaptosilane coupling agent and disperse it in 1000mL of anhydrous ethanol, add 20mL of N-methylmaleimide solution (equivalent to 2g of N-methylmaleimide) to the solution, adjust the pH of the solution to 7-8 with NaHCO3 solution, stir at 40℃ in the dark for 8h, wash 3 times with ethanol after the reaction is completed, and then vacuum dry at 60℃ for 12h to obtain N-methylmaleimide modified sepiolite.

[0041] The N-methylmaleimide-modified sepiolite prepared in this embodiment, along with sepiolite raw materials and N-methylmaleimide, were subjected to infrared spectroscopy. The testing conditions were: Bruker TENSOR 27 Fourier transform infrared spectrometer, wavenumber range 4000-400cm⁻¹. -1 4cm resolution -1 The scan was overlaid 32 times, and the results are as follows: Figure 1 As shown, it is evident that sepiolite and N-methylmaleimide combine through a chemical reaction to obtain the corresponding functional group structure.

[0042] Example 2

[0043] The only difference between this embodiment and Example 1 is that in step (3), 17 mL of N-methylmaleimide solution (equivalent to 1.7 g of N-methylmaleimide) is used instead of 20 mL of N-methylmaleimide solution. The remaining components and preparation methods are exactly the same as in Example 1.

[0044] Example 3

[0045] The only difference between this embodiment and Example 1 is that in step (3), 24 mL of N-methylmaleimide solution (equivalent to 2.4 g of N-methylmaleimide) is used instead of 20 mL of N-methylmaleimide solution. The remaining components and preparation methods are exactly the same as in Example 1.

[0046] Example 4

[0047] The only difference between this embodiment and Example 1 is that in step (2), 2g of 3-mercaptopropyltriethoxysilane is used instead of 2g of 3-mercaptopropyltrimethoxysilane. The remaining components and preparation methods are exactly the same as in Example 1.

[0048] Example 5

[0049] The only difference between this embodiment and Example 1 is that in step (2), 2g of 3-mercaptopropylmethyldimethoxysilane is used instead of 2g of 3-mercaptopropyltrimethoxysilane. The remaining components and preparation methods are exactly the same as in Example 1.

[0050] Comparative Example 1

[0051] The sepiolite in this comparative example, after acidification pretreatment and modification with a mercaptosilane coupling agent, was prepared without N-methylmaleimide modification, through the following steps:

[0052] (1) Disperse 20g of sepiolite raw material in 200g of dilute hydrochloric acid, stir at 60℃ for 4h, centrifuge and wash until neutral, dry at 100-130℃ for 16h, and then place the dried sepiolite in an oven and bake at 200℃ for 4h to obtain acid-pretreated sepiolite.

[0053] (2) Dissolve 2g of 3-mercaptopropyltrimethoxysilane in a mixed solvent of 45mL ethanol and 5mL water, adjust the pH of the solution to 4-5 with acetic acid, and then stir at 25℃ for 2h to obtain a solution containing mercaptosilane coupling agent; add the acidified sepiolite to the solution containing mercaptosilane coupling agent, stir and heat to 60℃ under reflux conditions, react for 8h, and introduce nitrogen gas during the reaction. After the reaction is completed, filter and wash three times with ethanol to remove unreacted mercaptosilane coupling agent. After washing, vacuum dry at 60℃ for 12h to obtain sepiolite modified with mercaptosilane coupling agent.

[0054] Comparative Example 2

[0055] The sepiolite in this comparative example was prepared by acidification pretreatment and modification with a mercaptosilane coupling agent, followed by modification with ethylenediamine (without N-methylmaleimide) through the following steps:

[0056] (1) Disperse 20g of sepiolite raw material in 200g of dilute hydrochloric acid, stir at 60℃ for 4h, centrifuge and wash until neutral, dry at 100-130℃ for 16h, and then place the dried sepiolite in an oven and bake at 200℃ for 4h to obtain acid-pretreated sepiolite.

[0057] (2) Dissolve 2g of 3-mercaptopropyltrimethoxysilane in a mixed solvent of 45mL ethanol and 5mL water, adjust the pH of the solution to 4-5 with acetic acid, and then stir at 25℃ for 2h to obtain a solution containing mercaptosilane coupling agent; add the acidified sepiolite to the solution containing mercaptosilane coupling agent, stir and heat to 60℃ under reflux conditions, react for 8h, and pass nitrogen gas during the reaction. After the reaction is completed, filter and wash three times with ethanol to remove unreacted mercaptosilane coupling agent. After washing, vacuum dry at 60℃ for 12h to obtain sepiolite modified with mercaptosilane coupling agent;

[0058] (3) 10g of mercaptosilane coupling agent modified sepiolite was dispersed in 1000mL of ethanol, 10mL of hydrogen peroxide was added, and the mixture was stirred at 60℃ for 2h. Then 2g of ethylenediamine was added, and the pH of the solution was adjusted to 7-8 with NaHCO3 solution. The reaction was carried out at 80℃ for 8h under nitrogen protection. After the reaction was completed, the mixture was washed 3 times with ethanol and then vacuum dried at 60℃ for 12h to obtain ethylenediamine modified sepiolite.

[0059] Comparative Example 3

[0060] The only difference between this comparative example and Example 1 is that 2g of hexadecyltrimethylammonium bromide (CTAB) is used instead of 2g of 3-mercaptopropyltrimethoxysilane in step (2). The remaining components and preparation methods are exactly the same as in Example 1.

[0061] Comparative Example 4

[0062] The only difference between this comparative example and Example 1 is that in step (2), 2g of isopropyltris(dioctylphosphoyloxy)titanate (TMC-201) is used instead of 2g of 3-mercaptopropyltrimethoxysilane. The remaining components and preparation methods are exactly the same as in Example 1.

[0063] Comparative Example 5

[0064] The only difference between this comparative example and Example 1 is that in step (2), 2g of distearate isopropyl aluminate (DL-411) is used instead of 2g of 3-mercaptopropyltrimethoxysilane. The remaining components and preparation methods are exactly the same as in Example 1.

[0065] Comparative Example 6

[0066] The only difference between this comparative example and Example 1 is that in step (3), 10g of mercaptosilane coupling agent modified sepiolite was dispersed in 1000mL of anhydrous ethanol, 5mL of N-methylmaleimide solution (equivalent to 0.5g N-methylmaleimide) was added to the solution, the pH of the solution was adjusted to 7-8 with NaHCO3 solution, and stirred at 40℃ in the dark for 8h. After the reaction was completed, it was washed 3 times with ethanol and then dried under vacuum at 60℃ for 12h to obtain N-methylmaleimide modified sepiolite. The remaining components and preparation methods were exactly the same as in Example 1.

[0067] Comparative Example 7

[0068] The only difference between this comparative example and Example 1 is that in step (3), 10g of mercaptosilane coupling agent modified sepiolite was dispersed in 1000mL of anhydrous ethanol, 50mL of N-methylmaleimide solution (equivalent to 5g of N-methylmaleimide) was added to the solution, the pH of the solution was adjusted to 7-8 with NaHCO3 solution, and stirred at 40℃ in the dark for 8h. After the reaction was completed, it was washed 3 times with ethanol and then vacuum dried at 60℃ for 12h to obtain N-methylmaleimide modified sepiolite. The remaining components and preparation methods were exactly the same as in Example 1.

[0069] Application Example 1

[0070] A flame-retardant cable material prepared from N-methylmaleimide-modified sepiolite is prepared through the following steps:

[0071] (1) Add 5 kg of metallocene polyethylene, 15 kg of ethylene-vinyl acetate copolymer, 7 kg of ethylene-α-olefin copolymer, 0.5 kg of tris(2,4-di-tert-butylphenyl) phosphite, 0.5 kg of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and 1 kg of polyethylene wax into a mixer for premixing. Set the temperature to 160℃ and mix for 5 min.

[0072] (2) Mix 15kg aluminum hydroxide, 30kg magnesium hydroxide and 2kg red phosphorus and add them to the internal mixer in two batches. After mixing for 3 minutes, add 1kg of N-methylmaleimide modified sepiolite prepared in Example 1 to the internal mixer. Set the temperature to 160℃ and continue mixing for 5 minutes.

[0073] (3) Set the temperature of each temperature section in the twin-screw extruder to 130℃, 150℃, 170℃ and 190℃, and the screw speed to 300 rpm / min. Feed the mixture from (2) into the twin-screw extruder to obtain flame-retardant cable material.

[0074] Application Example 2

[0075] The only difference between this application example and application example 1 is that in step (2), 3 kg of N-methylmaleimide modified sepiolite prepared in example 1 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0076] Application Example 3

[0077] The only difference between this application example and application example 1 is that in step (2), 5 kg of N-methylmaleimide modified sepiolite prepared in example 1 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0078] Application Example 4

[0079] The only difference between this application example and application example 1 is that in step (2), 1 kg of N-methylmaleimide modified sepiolite prepared in example 2 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0080] Application Example 5

[0081] The only difference between this application example and application example 1 is that in step (2), 1 kg of N-methylmaleimide modified sepiolite prepared in example 3 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0082] Application Example 6

[0083] The only difference between this application example and application example 1 is that in step (2), 1 kg of N-methylmaleimide modified sepiolite prepared in example 4 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0084] Application Example 7

[0085] The only difference between this application example and application example 1 is that in step (2), 1 kg of N-methylmaleimide modified sepiolite prepared in example 5 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0086] Comparative Application Example 1

[0087] The only difference between this comparative application example and application example 1 is that, in step (2), 1 kg of sepiolite modified with mercaptosilane coupling agent prepared in comparative example 1 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0088] Comparative Application Example 2

[0089] The only difference between this comparative application example and application example 1 is that in step (2), 1 kg of ethylenediamine-modified sepiolite prepared in comparative example 2 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0090] Comparative Application Example 3

[0091] The only difference between this comparative application example and application example 1 is that in step (2), 1 kg of N-methylmaleimide modified sepiolite prepared in comparative example 3 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0092] Comparative Application Example 4

[0093] The only difference between this comparative application example and application example 1 is that in step (2), 1 kg of N-methylmaleimide modified sepiolite prepared in comparative example 4 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0094] Comparative Application Example 5

[0095] The only difference between this comparative application example and application example 1 is that in step (2), 1 kg of N-methylmaleimide modified sepiolite prepared in comparative example 5 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0096] Comparative Application Example 6

[0097] The only difference between this comparative application example and application example 1 is that in step (2), 1 kg of N-methylmaleimide modified sepiolite prepared in comparative example 6 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0098] Comparative Application Example 7

[0099] The only difference between this comparative application example and application example 1 is that in step (2), 1 kg of N-methylmaleimide modified sepiolite prepared in comparative example 7 is added to the internal mixer, while the other components and preparation methods are exactly the same as in application example 1.

[0100] Comparative Application Example 8

[0101] The only difference between this comparative application example and application example 1 is that in step (2), 1 kg of sepiolite modified with mercaptosilane coupling agent prepared in comparative example 1 and 0.17 kg of N-methylmaleimide are added to the internal mixer. The remaining components and preparation methods are exactly the same as in application example 1.

[0102] Comparative Application Example 9

[0103] The only difference between this comparative application example and application example 1 is that in step (2), 5 kg of aluminum hydroxide, 30 kg of magnesium hydroxide and 2 kg of red phosphorus are used to replace 15 kg of aluminum hydroxide, 30 kg of magnesium hydroxide and 2 kg of red phosphorus in application example 1. The other components and preparation methods are exactly the same as in application example 1.

[0104] Comparative Application Example 10

[0105] The only difference between this comparative application example and application example 1 is that in step (2), 30 kg of aluminum hydroxide, 15 kg of magnesium hydroxide and 2 kg of red phosphorus are used to replace the 15 kg of aluminum hydroxide, 30 kg of magnesium hydroxide and 2 kg of red phosphorus in application example 1. The other components and preparation methods are exactly the same as in application example 1.

[0106] Comparative Application Example 11

[0107] The only difference between this comparative application example and application example 1 is that in step (2), 15 kg of aluminum hydroxide, 15 kg of magnesium hydroxide and 2 kg of red phosphorus are used to replace the 15 kg of aluminum hydroxide, 30 kg of magnesium hydroxide and 2 kg of red phosphorus in application example 1. The other components and preparation methods are exactly the same as in application example 1.

[0108] Comparative Application Example 12

[0109] The only difference between this comparative application example and application example 1 is that in step (2), 15 kg of aluminum hydroxide, 45 kg of magnesium hydroxide and 2 kg of red phosphorus are used to replace 15 kg of aluminum hydroxide, 30 kg of magnesium hydroxide and 2 kg of red phosphorus in application example 1. The other components and preparation methods are exactly the same as in application example 1.

[0110] Comparative Application Example 13

[0111] The only difference between this comparative application example and application example 1 is that in step (2), 45 kg of aluminum hydroxide and 2 kg of red phosphorus are used to replace 15 kg of aluminum hydroxide, 30 kg of magnesium hydroxide and 2 kg of red phosphorus in application example 1. The other components and preparation methods are exactly the same as in application example 1.

[0112] Comparative Application Example 14

[0113] The only difference between this comparative application example and application example 1 is that in step (2), 45 kg of magnesium hydroxide and 2 kg of red phosphorus are used to replace 15 kg of aluminum hydroxide, 30 kg of magnesium hydroxide and 2 kg of red phosphorus in application example 1. The other components and preparation methods are exactly the same as in application example 1.

[0114] Performance testing

[0115] 1. The tensile strength and elongation at break of the flame-retardant cable material samples prepared according to the corresponding use cases and comparative application examples of GB / T1040.3-2006 standard were tested. The test samples were prepared by hot pressing at 180℃ for 10 min using a flat vulcanizing machine. The sample size was the type 2 sample in GB / T1040.3-2006. The test results are shown in Table 2.

[0116] 2. The volume resistivity of the flame-retardant cable material samples prepared according to the GB / T1410-2006 standard, corresponding use cases and comparative application examples was tested. The sample size was 50×50×1mm. The test samples were prepared by hot pressing at 180℃ for 10min using a flat vulcanizing machine. The test temperature was 20℃. The test results are shown in Table 2.

[0117] 3. The oxygen index performance of the flame-retardant cable material samples prepared according to the GB / T2406.2-2009 standard, corresponding use cases and comparative application examples were tested. The sample size was 125×6.5×3mm. The test samples were prepared by hot pressing at 180℃ for 10min using a flat vulcanizing machine. The test results are shown in Table 2.

[0118] 4. Flame-retardant cable material samples prepared according to GB / T8323.2-2008 standard, corresponding use cases, and comparative application examples were subjected to smoke density testing. The sample size was 75×75×1mm, and the heat flux was 25kW / m². 2 Test samples were prepared by hot pressing at 180℃ for 10 minutes using a flat vulcanizing machine. The test results are shown in Table 2.

[0119] Table 2

[0120]

[0121]

[0122] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing N-methylmaleimide-modified sepiolite, characterized in that, Includes the following steps: (1) The sepiolite raw material is subjected to acid pretreatment to obtain acid pretreated sepiolite; (2) Add the acidified pretreated sepiolite to the silane coupling agent solution, stir and heat, and after the reaction, obtain silane coupling agent modified sepiolite; the silane coupling agent includes at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and 3-mercaptopropylmethyldimethoxysilane. (3) The silane coupling agent modified sepiolite is mixed and stirred with N-methylmaleimide solution to obtain the N-methylmaleimide modified sepiolite; the mass ratio of the silane coupling agent modified sepiolite to N-methylmaleimide is 10:(1.5-2.5).

2. The method as described in claim 1, characterized in that, In step (1), the acidification pretreatment step includes: adding sepiolite raw material to an acidic reagent and stirring; the acidic reagent includes at least one of hydrochloric acid and nitric acid; the stirring temperature is 60-80℃ and the stirring time is 2-4h.

3. The method as described in claim 1, characterized in that, The mass ratio of the sepiolite raw material to the silane coupling agent is (10-20):

1.

4. The method as described in claim 1, characterized in that, In step (2), the heating temperature is 40-60℃ and the reaction time is 6-8h.

5. The method as described in claim 1, characterized in that, In step (3), the concentration of the N-methylmaleimide solution is 50-100 g / L, and the solvent of the solution includes at least one of N,N-dimethyldiamide and dimethyl sulfoxide.

6. The method as described in claim 1, characterized in that, In step (3), the stirring temperature is 25-40℃ and the stirring time is 8-16h.

7. N-methylmaleimide-modified sepiolite prepared by any one of the methods described in claims 1-6.

8. A flame-retardant cable material, characterized in that, By weight, the raw materials of the flame-retardant cable material include 20-45 parts of polymer matrix, 41-65 parts of flame-retardant filler, 1-5 parts of N-methylmaleimide modified sepiolite as described in claim 7, 1-3 parts of antioxidant and 0.5-2 parts of lubricant. The flame-retardant filler comprises 15-25 parts aluminum hydroxide, 25-35 parts magnesium hydroxide, and 1-5 parts red phosphorus.

9. A method for preparing the flame-retardant cable material as described in claim 8, characterized in that, Includes the following steps: The raw materials are added to a mixer and mixed to obtain a compound. The compound is fed into a twin-screw extruder to obtain the flame-retardant cable material.

10. The application of the flame-retardant cable material as described in claim 9 in the manufacture of communication cables or power cables.

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