Novel modified flame-retardant polyethylene material

Abstract

The invention discloses a novel modified flame-retardant polyethylene material, and belongs to the technical field of flame-retardant materials.The novel modified flame-retardant polyethylene material is prepared by the steps that S1, cobalt nitrate hexahydrate, sodium molybdate and urea are added into deionized water, washed with water and ethyl alcohol respectively, separated and dried, and CoMo-L nanosheets are obtained; s2, the CoMo-L nanosheet is calcined in N2 / NH3 mixed gas, and a cobalt molybdenum nitride nanosheet is obtained; s3, adding the cobalt molybdenum nitride nanosheet into deionized water, stirring, adding magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and urea, separating and drying to obtain a CoMoN / Mg-AlLDH heterojunction flame retardant; s4, adding a product prepared in S3 into the carbon nanotube dispersion liquid, stirring, filtering and drying to obtain a pretreated flame retardant; and S5, carrying out melt blending on the pretreated flame retardant, the antioxidant and the modified polyethylene, and carrying out extrusion granulation to obtain the novel modified flame-retardant polyethylene material. The flame-retardant material prepared by the invention has good flame retardant property and mechanical property.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardants, and specifically to a novel modified flame retardant polyethylene material. Background Art

[0002] Polyethylene is one of the main types of polyolefin products. It has the advantages of variety, excellent performance, and abundant monomer sources, and is considered to be one of the most useful polyolefin materials. However, the flammability of traditional polyethylene materials limits its application in many occasions, especially in areas with high flame retardant requirements such as building materials, wires and cables, and vehicle interiors.

[0003] In order to overcome the defect of flammability, flame-retardant polyethylene materials have appeared on the market. Generally, inorganic flame retardants are compounded to improve the flame retardant properties of the materials. Inorganic flame retardants have the advantages of low water solubility and high flame retardant efficiency. However, the particle size of inorganic flame retardants prepared by the current process is generally 30-50μm, the particles are large, irregular in shape, and the particle size distribution is wide. When used, they must be mechanically crushed or air-flow crushed to less than 10μm, which is difficult to process. In addition, inorganic flame retardants have poor compatibility with polymer materials, are prone to agglomeration, and are difficult to be evenly dispersed in polymers, resulting in rapid deterioration of the mechanical properties of the material and affecting the comprehensive performance of the terminal product.

[0004] Therefore, how to develop a polyethylene material with simple process and both mechanical strength and flame retardancy is a problem that needs to be solved urgently. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides a novel modified flame-retardant polyethylene material, which solves the problems raised in the above-mentioned background technology.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: A novel modified flame-retardant polyethylene material, the preparation method of which comprises the following steps: S1. By weight, 5 parts of cobalt nitrate hexahydrate, 2-3 parts of sodium molybdate and 1-2 parts of urea are added to 40-60 parts of deionized water, stirred evenly for hydrothermal reaction, the reaction temperature is controlled to be 130-150° C., the reaction time is 6-10 hours, and a precursor containing Co hydroxide and Mo hydroxide is obtained, and then washed twice with water and once with ethanol, respectively, and the product is separated and dried to obtain CoMo-L nanosheets; S2, the CoMo-L nanosheets prepared in S1 were heated in N 2 / NH 3 The cobalt molybdenum nitride (CoMoN) nanosheets were obtained by calcination in a mixed gas, wherein the N 2 With NH 3The volume ratio is 5:1~2, the calcination temperature is 500~600℃, and the calcination time is 2~3h; S3, adding the cobalt molybdenum nitride (CoMoN) nanosheets prepared in S2 to 40-60 parts of deionized water by weight, stirring evenly, then adding 1-2 parts of magnesium nitrate hexahydrate, 3.5-4.5 parts of aluminum nitrate nonahydrate and 3-4 parts of urea, carrying out a hydrothermal reaction, controlling the reaction temperature to 140-160° C., the reaction time to 4-6 hours, separating and drying the product to obtain a CoMoN / Mg-AlLDH heterojunction flame retardant; S4, adding the CoMoN / Mg-AlLDH heterojunction flame retardant prepared in S3 to 60-100 parts of the carbon nanotube dispersion, stirring with ultrasound for 10-20 minutes, filtering and drying to obtain a pretreated flame retardant; S5. Melt-blending the pretreated flame retardant, antioxidant and modified polyethylene obtained in S4, and extruding and granulating them to obtain a new modified flame retardant polyethylene material.

[0007] Furthermore, the carbon nanotube dispersion in S4 is a dispersion of carboxylated carbon nanotubes in N,N-dimethylformamide (DMF).

[0008] Furthermore, the mass fraction of the carboxylated carbon nanotubes in the carbon nanotube dispersion is 0.5-1%.

[0009] Furthermore, the method for preparing the modified polyethylene in S4 comprises the following steps: Q1; the following raw materials are prepared by weight: 100 parts of polyethylene, 0.8-1.2 parts of tert-butyl peroxybenzoate and 4-6 parts of glycidyl methacrylate, and the above raw materials are mixed uniformly to obtain a mixed material; Q2: The mixed material is melt-extruded through a twin-screw extruder, and the extruded material strips are cooled and pelletized to obtain modified polyethylene.

[0010] Furthermore, the mass ratios of the pretreated flame retardant, antioxidant and modified polyethylene in S5 are 14-16: (1.5-2.5): 100 respectively.

[0011] Furthermore, the antioxidant is 6-di-tert-butyl-p-cresol.

[0012] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art: 1. The present invention adopts a specific method to prepare a CoMoN / Mg-AlLDH heterojunction flame retardant. The CoMoN / Mg-AlLDH heterojunction flame retardant is loaded with carboxylated carbon nanotubes and then acts together with modified polyethylene to achieve a strong interface interaction between the inorganic flame retardant and the polymer matrix material, thereby obtaining a polyethylene material with both mechanical strength and flame retardancy.

[0013] 2. The CoMoN / Mg-AlLDH heterojunction flame retardant provided by the present invention has a small particle size and a uniform particle size distribution. At the same time, the surface of the flame retardant particles has fine fuzzy protrusions, so that it can serve as an excellent carrier of carbon nanotubes and achieve uniform dispersion of carboxylated carbon nanotubes, so that the carboxylated carbon nanotubes can be used as a reinforcing material to improve the mechanical properties of modified polyethylene. At the same time, it can also effectively improve the interfacial force between the inorganic flame retardant and the resin matrix, and improve the thermal insulation and flame retardant properties of the polyethylene material.

[0014] 3. By modifying polyethylene, a branched structure is introduced into the polyethylene molecular chain, giving polyethylene a certain polarity and reactivity, thereby increasing the thermal decomposition temperature of the material and making it have higher heat resistance. At the same time, the carboxylated carbon nanotubes and the modified polyethylene can produce a chemical reaction, so that the inorganic particles in the flame retardant form a stable inorganic composite barrier layer in the polyethylene matrix, which can isolate oxygen from contact with the matrix, prevent molten dripping, and improve the flame retardancy of the polyethylene material. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a scanning electron microscope image of the CoMoN / Mg-AlLDH heterojunction flame retardant in the preparation of a new modified flame-retardant polyethylene material of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Example 1

[0018] A novel modified flame-retardant polyethylene material, the preparation method of which comprises the following steps: S1. By weight, 5 parts of cobalt nitrate hexahydrate, 2.5 parts of sodium molybdate and 1.5 parts of urea were added to 50 parts of deionized water, and the mixture was stirred evenly for hydrothermal reaction. The reaction temperature was controlled to be 140° C. and the reaction time was 8 h to obtain a precursor containing Co hydroxide and Mo hydroxide, and then the precursor was washed twice with water and once with ethanol, and the product was separated and dried to obtain CoMo-L nanosheets; S2, the CoMo-L nanosheets prepared in S1 were heated to N 2 / NH 3 The cobalt molybdenum nitride (CoMoN) nanosheets were obtained by calcination in a mixed gas, wherein the N 2 With NH 3 The volume ratio is 5:1, the calcination temperature is 550℃, and the calcination time is 2h; S3, adding the cobalt molybdenum nitride (CoMoN) nanosheets prepared in S2 to 50 parts of deionized water by weight, stirring evenly, then adding 1.5 parts of magnesium nitrate hexahydrate, 3.5 parts of aluminum nitrate nonahydrate and 4 parts of urea, carrying out a hydrothermal reaction, controlling the reaction temperature to 150° C., the reaction time to 5 hours, separating and drying the product, and obtaining a CoMoN / Mg-AlLDH heterojunction flame retardant; S4, adding the CoMoN / Mg-AlLDH heterojunction flame retardant prepared in S3 to 80 parts of carbon nanotube dispersion, ultrasonically stirring for 15 minutes, filtering and drying to obtain a pretreated flame retardant, wherein the carbon nanotube dispersion in S4 is a dispersion of carboxylated carbon nanotubes in N,N-dimethylformamide (DMF), wherein the mass fraction of the carboxylated carbon nanotubes is 0.8%; S5. Melt-blending the pretreated flame retardant, antioxidant and modified polyethylene obtained in S4, and extruding and granulating to obtain a novel modified flame-retardant polyethylene material; the antioxidant is 6-di-tert-butyl-p-cresol.

[0019] The method for preparing the modified polyethylene described in S4 comprises the following steps: Q1; the following raw materials are prepared by weight: 100 parts of polyethylene, 0.8-1.2 parts of tert-butyl peroxybenzoate and 4-6 parts of glycidyl methacrylate, and the above raw materials are mixed uniformly to obtain a mixed material; Q2: The mixed material is melt-extruded through a twin-screw extruder, and the extruded material strips are cooled and pelletized to obtain modified polyethylene.

[0020] The mass ratios of pretreated flame retardant, antioxidant and modified polyethylene in S5 are 15:2:100 respectively.

[0021] Example 2

[0022] A novel modified flame-retardant polyethylene material, the preparation method of which comprises the following steps: S1. By weight, 5 parts of cobalt nitrate hexahydrate, 2 parts of sodium molybdate and 1 part of urea were added to 40 parts of deionized water, and the mixture was stirred evenly for hydrothermal reaction. The reaction temperature was controlled to be 130° C. and the reaction time was 6 h to obtain a precursor containing Co hydroxide and Mo hydroxide, and then the precursors were washed twice with water and once with ethanol, respectively, and the products were separated and dried to obtain CoMo-L nanosheets; S2, the CoMo-L nanosheets prepared in S1 were heated to N 2 / NH 3 The cobalt molybdenum nitride (CoMoN) nanosheets were obtained by calcination in a mixed gas, wherein the N 2 With NH 3 The volume ratio is 5:1, the calcination temperature is 500℃, and the calcination time is 2h; S3, adding the cobalt molybdenum nitride (CoMoN) nanosheets prepared in S2 to 40 parts of deionized water by weight, stirring evenly, then adding 1 part of magnesium nitrate hexahydrate, 3.5 parts of aluminum nitrate nonahydrate and 3 parts of urea, carrying out a hydrothermal reaction, controlling the reaction temperature to 140° C., the reaction time to 4 hours, separating and drying the product, and obtaining a CoMoN / Mg-AlLDH heterojunction flame retardant; S4, adding the CoMoN / Mg-AlLDH heterojunction flame retardant prepared in S3 to 60 parts of carbon nanotube dispersion, ultrasonically stirring for 10 minutes, filtering and drying to obtain a pretreated flame retardant; S5. Melt-blending the pretreated flame retardant, antioxidant and modified polyethylene obtained in S4, and extruding and granulating to obtain a novel modified flame-retardant polyethylene material; the antioxidant is 6-di-tert-butyl-p-cresol.

[0023] The carbon nanotube dispersion in S4 is a dispersion of carboxylated carbon nanotubes in N,N-dimethylformamide (DMF), wherein the mass fraction of the carboxylated carbon nanotubes is 0.5%; The method for preparing the modified polyethylene described in S4 comprises the following steps: Q1; the following raw materials are prepared by weight: 100 parts of polyethylene, 0.8 parts of tert-butyl peroxybenzoate and 4-6 parts of glycidyl methacrylate, and the above raw materials are mixed uniformly to obtain a mixed material; Q2: The mixed material is melt-extruded through a twin-screw extruder, and the extruded material strips are cooled and pelletized to obtain modified polyethylene.

[0024] The mass ratios of pretreated flame retardant, antioxidant and modified polyethylene in S5 are 14:1.5:100 respectively.

[0025] Example 3

[0026] A novel modified flame-retardant polyethylene material, the preparation method of which comprises the following steps: S1. By weight, 5 parts of cobalt nitrate hexahydrate, 3 parts of sodium molybdate and 2 parts of urea were added to 60 parts of deionized water, and the mixture was stirred evenly for hydrothermal reaction. The reaction temperature was controlled to be 150° C. and the reaction time was 10 h to obtain a precursor containing Co hydroxide and Mo hydroxide, and then the precursors were washed twice with water and once with ethanol, respectively, and the products were separated and dried to obtain CoMo-L nanosheets; S2, the CoMo-L nanosheets prepared in S1 were heated to N 2 / NH 3 The cobalt molybdenum nitride (CoMoN) nanosheets were obtained by calcination in a mixed gas, wherein the N 2 With NH 3 The volume ratio is 5:2, the calcination temperature is 600℃, and the calcination time is 3h; S3, adding the cobalt molybdenum nitride (CoMoN) nanosheets prepared in S2 to 60 parts of deionized water by weight, stirring evenly, then adding 2 parts of magnesium nitrate hexahydrate, 4.5 parts of aluminum nitrate nonahydrate and 4 parts of urea, carrying out a hydrothermal reaction, controlling the reaction temperature to 160° C., the reaction time to 6 hours, separating and drying the product to obtain a CoMoN / Mg-AlLDH heterojunction flame retardant; S4, adding the CoMoN / Mg-AlLDH heterojunction flame retardant prepared in S3 to 100 parts of the carbon nanotube dispersion by weight, stirring with ultrasound for 20 minutes, filtering and drying to obtain a pretreated flame retardant; S5. Melt-blending the pretreated flame retardant, antioxidant and modified polyethylene obtained in S4, and extruding and granulating to obtain a novel modified flame-retardant polyethylene material; the antioxidant is 6-di-tert-butyl-p-cresol.

[0027] The carbon nanotube dispersion in S4 is a dispersion of carboxylated carbon nanotubes in N,N-dimethylformamide (DMF), wherein the mass fraction of the carboxylated carbon nanotubes is 1%; The method for preparing the modified polyethylene described in S4 comprises the following steps: Q1; the following raw materials are prepared by weight: 100 parts of polyethylene, 1.2 parts of tert-butyl peroxybenzoate and 6 parts of glycidyl methacrylate, and the above raw materials are mixed uniformly to obtain a mixed material; Q2: The mixed material is melt-extruded through a twin-screw extruder, and the extruded material strips are cooled and pelletized to obtain modified polyethylene.

[0028] The mass ratios of pretreated flame retardant, antioxidant and modified polyethylene in S5 are 16:2.5:100 respectively.

[0029] Example 4

[0030] A novel modified flame-retardant polyethylene material, the preparation method of which comprises the following steps: S1. By weight, 5 parts of cobalt nitrate hexahydrate, 2.3 parts of sodium molybdate and 1.2 parts of urea were added to 45 parts of deionized water, and the mixture was stirred evenly for hydrothermal reaction. The reaction temperature was controlled to be 135° C. and the reaction time was 7 h to obtain a precursor containing Co hydroxide and Mo hydroxide, and then the precursor was washed twice with water and once with ethanol, and the product was separated and dried to obtain CoMo-L nanosheets; S2, the CoMo-L nanosheets prepared in S1 were heated to N 2 / NH 3 The cobalt molybdenum nitride (CoMoN) nanosheets were obtained by calcination in a mixed gas, wherein the N 2 With NH 3 The volume ratio is 5:1.2, the calcination temperature is 520°C, and the calcination time is 2.3h; S3, adding the cobalt molybdenum nitride (CoMoN) nanosheets prepared in S2 to 45 parts of deionized water by weight, stirring evenly, then adding 1.2 parts of magnesium nitrate hexahydrate, 3.7 parts of aluminum nitrate nonahydrate and 3.3 parts of urea, carrying out a hydrothermal reaction, controlling the reaction temperature to 145° C., the reaction time to 4.5 h, separating and drying the product to obtain a CoMoN / Mg-AlLDH heterojunction flame retardant; S4, adding the CoMoN / Mg-AlLDH heterojunction flame retardant prepared in S3 to 70 parts of the carbon nanotube dispersion, ultrasonically stirring for 12 minutes, filtering and drying to obtain a pretreated flame retardant; S5. Melt-blending the pretreated flame retardant, antioxidant and modified polyethylene obtained in S4, and extruding and granulating to obtain a novel modified flame-retardant polyethylene material; the antioxidant is 6-di-tert-butyl-p-cresol.

[0031] The carbon nanotube dispersion in S4 is a dispersion of carboxylated carbon nanotubes in N,N-dimethylformamide (DMF), wherein the mass fraction of the carboxylated carbon nanotubes is 0.6%; The method for preparing the modified polyethylene described in S4 comprises the following steps: Q1; the following raw materials are prepared by weight: 100 parts of polyethylene, 0.9 parts of tert-butyl peroxybenzoate and 4.5 parts of glycidyl methacrylate, and the above raw materials are mixed uniformly to obtain a mixed material; Q2: The mixed material is melt-extruded through a twin-screw extruder, and the extruded material strips are cooled and pelletized to obtain modified polyethylene.

[0032] The mass ratios of pretreated flame retardant, antioxidant and modified polyethylene in S5 are 14.5:1.6:100 respectively.

[0033] Example 5

[0034] A novel modified flame-retardant polyethylene material, the preparation method of which comprises the following steps: S1. By weight, 5 parts of cobalt nitrate hexahydrate, 2.8 parts of sodium molybdate and 1.7 parts of urea were added to 55 parts of deionized water, and the mixture was stirred evenly for hydrothermal reaction. The reaction temperature was controlled to be 145° C. and the reaction time was 9 h to obtain a precursor containing Co hydroxide and Mo hydroxide, and then the precursor was washed twice with water and once with ethanol, and the product was separated and dried to obtain CoMo-L nanosheets; S2, the CoMo-L nanosheets prepared in S1 were heated to N 2 / NH 3 The cobalt molybdenum nitride (CoMoN) nanosheets were obtained by calcination in a mixed gas, wherein the N 2 With NH 3 The volume ratio is 5:1.8, the calcination temperature is 590°C, and the calcination time is 2.8h; S3, adding the cobalt molybdenum nitride (CoMoN) nanosheets prepared in S2 to 55 parts of deionized water by weight, stirring evenly, then adding 1.7 parts of magnesium nitrate hexahydrate, 4.2 parts of aluminum nitrate nonahydrate and 3.8 parts of urea, carrying out a hydrothermal reaction, controlling the reaction temperature to 155° C., the reaction time to 5.5 h, separating and drying the product to obtain a CoMoN / Mg-AlLDH heterojunction flame retardant; S4, adding the CoMoN / Mg-AlLDH heterojunction flame retardant prepared in S3 to 90 parts of the carbon nanotube dispersion, ultrasonically stirring for 18 minutes, filtering and drying to obtain a pretreated flame retardant; S5. Melt-blending the pretreated flame retardant, antioxidant and modified polyethylene obtained in S4, and extruding and granulating to obtain a novel modified flame-retardant polyethylene material; the antioxidant is 6-di-tert-butyl-p-cresol.

[0035] The carbon nanotube dispersion in S4 is a dispersion of carboxylated carbon nanotubes in N,N-dimethylformamide (DMF), wherein the mass fraction of the carboxylated carbon nanotubes is 0.9%; The method for preparing the modified polyethylene described in S4 comprises the following steps: Q1; the following raw materials are prepared by weight: 100 parts of polyethylene, 1.1 parts of tert-butyl peroxybenzoate and 4 to 6 parts of glycidyl methacrylate, and the above raw materials are mixed uniformly to obtain a mixed material; Q2: The mixed material is melt-extruded through a twin-screw extruder, and the extruded material strips are cooled and pelletized to obtain modified polyethylene.

[0036] The mass ratios of pretreated flame retardant, antioxidant and modified polyethylene in S5 are 14~16:1.5~2.5:100 respectively.

[0037] Comparative Example 1 The only difference from Example 1 is that in the preparation of the carbon nanotube dispersion in S4, the carboxylated carbon nanotubes are replaced by ordinary carbon nanotubes.

[0038] A novel modified flame-retardant polyethylene material, the preparation method of which comprises the following steps: S1. By weight, 5 parts of cobalt nitrate hexahydrate, 2.5 parts of sodium molybdate and 1.5 parts of urea were added to 50 parts of deionized water, and the mixture was stirred evenly for hydrothermal reaction. The reaction temperature was controlled to be 140° C. and the reaction time was 8 h to obtain a precursor containing Co hydroxide and Mo hydroxide, and then the precursor was washed twice with water and once with ethanol, and the product was separated and dried to obtain CoMo-L nanosheets; S2, the CoMo-L nanosheets prepared in S1 were heated to N 2 / NH 3 The cobalt molybdenum nitride (CoMoN) nanosheets were obtained by calcination in a mixed gas, wherein the N 2 With NH 3 The volume ratio is 5:1, the calcination temperature is 550℃, and the calcination time is 2h; S3, adding the cobalt molybdenum nitride (CoMoN) nanosheets prepared in S2 to 50 parts of deionized water by weight, stirring evenly, then adding 1.5 parts of magnesium nitrate hexahydrate, 3.5 parts of aluminum nitrate nonahydrate and 4 parts of urea, carrying out a hydrothermal reaction, controlling the reaction temperature to 150° C., the reaction time to 5 hours, separating and drying the product, and obtaining a CoMoN / Mg-AlLDH heterojunction flame retardant; S4, adding the CoMoN / Mg-AlLDH heterojunction flame retardant prepared in S3 to 80 parts of carbon nanotube dispersion, ultrasonically stirring for 15 minutes, filtering and drying to obtain a pretreated flame retardant, wherein the carbon nanotube dispersion in S4 is a dispersion of carbon nanotubes in N,N-dimethylformamide (DMF), wherein the mass fraction of the carbon nanotubes is 0.8%; S5. Melt-blending the pretreated flame retardant, antioxidant and modified polyethylene obtained in S4, and extruding and granulating to obtain a novel modified flame-retardant polyethylene material; the antioxidant is 6-di-tert-butyl-p-cresol.

[0039] Comparative Example 2 The only difference from Example 1 is that glycidyl methacrylate is not added in the preparation of the modified polyethylene in S4.

[0040] The method for preparing the modified polyethylene described in S4 comprises the following steps: Q1; the following raw materials are prepared by weight: 100 parts of polyethylene and 0.8-1.2 parts of tert-butyl peroxybenzoate, and the above raw materials are mixed uniformly to obtain a mixed material; Q2: The mixed material is melt-extruded through a twin-screw extruder, and the extruded material strips are cooled and pelletized to obtain modified polyethylene.

[0041] Comparative Example 3 The only difference from Example 1 is that in step 4, the carboxylated carbon nanotubes are replaced by ordinary carbon nanotubes in the carbon nanotube dispersion, and glycidyl methacrylate is not added in the preparation of the modified polyethylene.

[0042] A novel modified flame-retardant polyethylene material, the preparation method of which comprises the following steps: S1. By weight, 5 parts of cobalt nitrate hexahydrate, 2.5 parts of sodium molybdate and 1.5 parts of urea were added to 50 parts of deionized water, and the mixture was stirred evenly for hydrothermal reaction. The reaction temperature was controlled to be 140° C. and the reaction time was 8 h to obtain a precursor containing Co hydroxide and Mo hydroxide, and then the precursor was washed twice with water and once with ethanol, and the product was separated and dried to obtain CoMo-L nanosheets; S2, the CoMo-L nanosheets prepared in S1 were heated to N 2 / NH 3 The cobalt molybdenum nitride (CoMoN) nanosheets were obtained by calcination in a mixed gas, wherein the N 2 With NH 3 The volume ratio is 5:1, the calcination temperature is 550℃, and the calcination time is 2h; S3, adding the cobalt molybdenum nitride (CoMoN) nanosheets prepared in S2 to 50 parts of deionized water by weight, stirring evenly, then adding 1.5 parts of magnesium nitrate hexahydrate, 3.5 parts of aluminum nitrate nonahydrate and 4 parts of urea, carrying out a hydrothermal reaction, controlling the reaction temperature to 150° C., the reaction time to 5 hours, separating and drying the product, and obtaining a CoMoN / Mg-AlLDH heterojunction flame retardant; S4, adding the CoMoN / Mg-AlLDH heterojunction flame retardant prepared in S3 to 80 parts of carbon nanotube dispersion, ultrasonically stirring for 15 minutes, filtering and drying to obtain a pretreated flame retardant, wherein the carbon nanotube dispersion in S4 is a dispersion of carbon nanotubes in N,N-dimethylformamide (DMF), wherein the mass fraction of the carbon nanotubes is 0.8%; S5. Melt-blending the pretreated flame retardant, antioxidant and modified polyethylene obtained in S4, and extruding and granulating to obtain a novel modified flame-retardant polyethylene material; the antioxidant is 6-di-tert-butyl-p-cresol.

[0043] The method for preparing the modified polyethylene described in S4 comprises the following steps: Q1; the following raw materials are prepared by weight: 100 parts of polyethylene and 0.8-1.2 parts of tert-butyl peroxybenzoate, and the above raw materials are mixed uniformly to obtain a mixed material; Q2: The mixed material is melt-extruded through a twin-screw extruder, and the extruded material strips are cooled and pelletized to obtain modified polyethylene.

[0044] Performance Testing The materials obtained in the embodiments and comparative examples were made into corresponding shapes according to different test standards and subjected to the following performance tests. The specific results are shown in Table 1: 1. The limiting oxygen index is tested according to GB / T 2406.2-2009 "Test method for combustion performance of plastics" standard; 2. The tensile strength is tested according to GB / T 1040-2006 "Determination of tensile properties of plastics" standard; Table 1

[0045] Result analysis: It can be seen from Examples 1 to 5 and Table 1 that the novel modified flame-retardant polyethylene material prepared by the present invention has good flame retardant properties and good mechanical properties.

[0046] Compared with Example 1, the carboxylated carbon nanotubes were replaced with ordinary carbon nanotubes in Comparative Example 1. As a result, the tensile strength and limiting oxygen index of the new modified polyethylene material prepared in Comparative Example 1 were significantly reduced, indicating that replacing ordinary carbon nanotubes with carboxylated carbon nanotubes can improve the flame retardancy and mechanical properties of the prepared new modified flame-retardant polyethylene material.

[0047] Combining the contents of Example 1 and the data in Table 1, it can be seen that the mechanical properties and flame retardancy of the new modified flame-retardant polyethylene material prepared in Comparative Example 2 deteriorate, indicating that the addition of glycidyl methacrylate can improve the mechanical properties and flame retardancy of the prepared new modified flame-retardant polyethylene material.

[0048] In the preparation of the new modified flame-retardant polyethylene material in Comparative Example 3, the carboxylated carbon nanotubes are replaced with ordinary carbon nanotubes, and no glycidyl methacrylate is added. Combining the contents of Comparative Examples 1 and 2 and the contents of Example 1 and the data in Table 1, it can be seen that the addition of carboxylated carbon nanotubes and glycidyl methacrylate can make the carbon nanotube dispersion and modified polyethylene produce a synergistic effect in improving the mechanical properties and flame retardancy of the prepared new modified polyethylene material.

[0049] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A new type of modified flame retardant polyethylene material, characterized by: The preparation method comprises the following steps: S1. By weight, 5 parts of cobalt nitrate hexahydrate, 2-3 parts of sodium molybdate and 1-2 parts of urea are added to 40-60 parts of deionized water, stirred evenly for hydrothermal reaction, the reaction temperature is controlled to be 130-150° C., the reaction time is 6-10 hours, and a precursor containing Co hydroxide and Mo hydroxide is obtained, and then washed twice with water and once with ethanol, respectively, and the product is separated and dried to obtain CoMo-L nanosheets; S2, calcining the CoMo-L nanosheets prepared in S1 in a N2 / NH3 mixed gas to obtain cobalt molybdenum nitride nanosheets, wherein the volume ratio of N2 to NH3 in the mixed gas is 5:1-2, the calcination temperature is 500-600°C, and the calcination time is 2-3h; S3, adding the cobalt molybdenum nitride nanosheets prepared in S2 to 40-60 parts of deionized water by weight, stirring evenly, then adding 1-2 parts of magnesium nitrate hexahydrate, 3.5-4.5 parts of aluminum nitrate nonahydrate and 3-4 parts of urea, carrying out a hydrothermal reaction, controlling the reaction temperature to 140-160° C., the reaction time to 4-6 hours, separating and drying the product to obtain a CoMoN / Mg-AlLDH heterojunction flame retardant; S4, adding the CoMoN / Mg-AlLDH heterojunction flame retardant prepared in S3 to 60-100 parts of the carbon nanotube dispersion, stirring with ultrasound for 10-20 minutes, filtering and drying to obtain a pretreated flame retardant; S5. Melt-blending the pretreated flame retardant, antioxidant and modified polyethylene obtained in S4, and extruding and granulating them to obtain a new modified flame retardant polyethylene material.

2. A novel modified flame-retardant polyethylene material according to claim 1, characterized in that: The carbon nanotube dispersion in S4 is a dispersion of carboxylated carbon nanotubes in N,N-dimethylformamide (DMF).

3. A novel modified flame-retardant polyethylene material according to claim 2, characterized in that: The mass fraction of the carboxylated carbon nanotubes in the carbon nanotube dispersion is 0.5-1%.

4. The novel modified flame-retardant polyethylene material according to claim 1, characterized in that: The method for preparing the modified polyethylene in S4 comprises the following steps: Q1; the following raw materials are prepared by weight: 100 parts of polyethylene, 0.8-1.2 parts of tert-butyl peroxybenzoate and 4-6 parts of glycidyl methacrylate, and the above raw materials are mixed uniformly to obtain a mixed material; Q2: The mixed material is melt-extruded through a twin-screw extruder, and the extruded material strips are cooled and pelletized to obtain modified polyethylene.

5. The novel modified flame-retardant polyethylene material according to claim 1, characterized in that: The mass ratios of the pretreated flame retardant, antioxidant and modified polyethylene in S5 are (14-16): (1.5-2.5): 100 respectively.

6. The novel modified flame-retardant polyethylene material according to claim 1, characterized in that: The antioxidant is 6-di-tert-butyl-p-cresol.

Images