Nylon 66 composition and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer materials, and provides a nylon 66 composition and a preparation method thereof, and the nylon 66 composition comprises the following components in parts by weight: 100 parts of nylon 66 resin, modified ammonium polyphosphate, 3-5 parts of modified carbon nanotubes, 5-10 parts of modified carbon nanotubes, 0.10-0.28 part of a lubricant, and 0.1-0.5 part of an antioxidant. The preparation method comprises the following steps: step 1, weighing the raw materials in parts by weight, adding the nylon 66 resin, the modified ammonium polyphosphate, the modified carbon nanotubes, the lubricant and the antioxidant into a mixer, and uniformly mixing to obtain a mixture; and step 2, putting the mixture obtained in the step 1 into a double-screw basic machine, mixing, melting, extruding and granulating to obtain the nylon 66 composition. The nylon 66 composition provided by the invention has excellent mechanical property and flame retardant property.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a nylon 66 composition and its preparation method. Background Technology

[0002] Nylon is a common name for polyamide resin. Nylon resin is a general term for a large class of polymers, of which nylon 66 and nylon 6 account for more than 90% of the production. Nylon resin has excellent comprehensive properties and is widely used due to its high mechanical strength, good toughness, fatigue resistance, self-lubricating properties, low coefficient of friction, wear resistance, heat resistance (can be used for a long time at 100℃), and easy modification and molding.

[0003] Unmodified nylon has poor flame retardant properties, achieving only a UL94 V-2 rating in vertical burning, with an oxygen index of around 24. Furthermore, it drips during combustion, classifying it as a flammable material that can easily ignite fires during use. Especially in the electronics industry, countless fires have been caused by nylon, resulting in enormous losses. Therefore, flame retardant modification of nylon has become a topic of common concern and research for both academia and industry.

[0004] Currently, the main method used in the flame retardant field for nylon is to add halogenated flame retardants to the resin matrix. However, halogenated flame retardant materials produce a large amount of smoke and toxic gases during combustion, causing secondary harm and pollution to people and the environment. Therefore, halogen-free flame retardant systems have attracted increasing attention and development. Halogen-free flame retardant systems in the nylon field mainly consist of inorganic flame retardants such as red phosphorus, diethylaluminum hypophosphite, nitrogen-based flame retardants, and magnesium hydroxide. However, red phosphorus flame retardants have limitations due to their inherent color, and the high proportion of other halogen-free flame retardants leads to significant damage to the material's mechanical properties, thus limiting their use. To promote green and environmentally friendly concepts, the automotive and electronics industries are constantly raising their requirements for materials, making it essential to develop halogen-free flame retardant products with lower toxicity and excellent mechanical properties.

[0005] Therefore, it is of great significance to develop a green, halogen-free, flame-retardant nylon composition with excellent mechanical properties. Summary of the Invention

[0006] The purpose of this invention is to provide a nylon 66 composition and its preparation method to solve the technical problem of poor flame retardant properties of nylon 66 materials in the prior art.

[0007] The objective of this invention can be achieved through the following technical solutions: The first aspect of the present invention provides a nylon 66 composition, comprising, by weight, the following components: 100 parts of Nylon 66 resin; 3-5 parts of modified ammonium polyphosphate; 5-10 parts of modified carbon nanotubes; Lubricant 0.10–0.28 parts; Antioxidant 0.1–0.5 parts; The modified ammonium polyphosphate is prepared through the following steps: Silane coupling agent KH-550 and deionized water were added to anhydrous ethanol, heated to 50-55℃, and stirred for 0.5-1.0 h to obtain a hydrolysate of silane coupling agent KH-550. Ammonium polyphosphate and the hydrolysate of silane coupling agent KH-550 were added to anhydrous ethanol, heated to 60-65℃, and stirred for 1.0-1.5 h. The mixture was then filtered and dried in a vacuum drying oven at 60℃ for 3 h to obtain modified ammonium polyphosphate.

[0008] As a further embodiment of the present invention, the ratio of silane coupling agent KH-550, deionized water and anhydrous ethanol is 20g:8g:72g; the ratio of ammonium polyphosphate, hydrolysate of silane coupling agent KH-550 and anhydrous ethanol is 40-42g:2.0-2.6g:150mL.

[0009] Ammonium polyphosphate is a novel, green, non-toxic, and environmentally friendly inorganic phosphorus flame retardant. It boasts advantages such as high phosphorus content, high nitrogen content, good thermal stability, long-lasting flame retardant performance, and non-toxic smoke suppression. However, due to its high hygroscopicity and poor compatibility with polymer materials, it may precipitate after prolonged use. Furthermore, its hygroscopic nature can cause materials to become damp, affecting their mechanical properties. To improve the hydrophobicity, flame retardancy, and resin compatibility of ammonium polyphosphate, this invention uses the silane coupling agent KH-550 to modify it. The hydroxyl groups of the coupling agent reacted chemically with the hydroxyl groups on the surface of ammonium polyphosphate. The surface structure of APP modified by the silane coupling agent KH-550 changed significantly, the dispersibility was well improved, and the interfacial compatibility with the resin was enhanced. Compared with unmodified ammonium polyphosphate, the introduction of coupling agent KH-550 had a positive effect on the thermal decomposition of ammonium polyphosphate into char, resulting in better flame retardancy and significant smoke suppression. The maximum heat release rate, total heat release, smoke release rate, and total smoke release rate all reached the minimum values, effectively playing a role in flame retardancy and smoke suppression of the composite material.

[0010] As a further aspect of the present invention, the modified carbon nanotubes are prepared by the following steps: Sodium phytate and carboxylated carbon nanotubes were added to deionized water and ultrasonically dispersed until homogeneous to obtain solution A. Cobalt nitrate hexahydrate and copper nitrate were added to the deionized water solution and stirred until homogeneous to obtain solution B. Solution B was slowly added to solution A and stirred for 0.5–1 h. Then, the mixture was placed in a reactor at 195–200 °C and the reaction was continued for 12–14 h. After the reaction was completed, the mixture was filtered, centrifuged, washed, and dried to obtain modified carbon nanotubes.

[0011] As a further embodiment of the present invention, the ratio of sodium phytate, carboxylated carbon nanotubes and deionized water in solution A is 4.1-4.2 g: 4.0-4.1 g: 50 mL; and the ratio of cobalt nitrate hexahydrate, copper nitrate and deionized water in solution B is 3.84-3.86 g: 3.18-3.20 g: 100 mL.

[0012] Carbon nanotubes can serve as fillers to enhance the mechanical properties of composite materials, and also as flame retardants. The dimensionality of carbon nanotube particles can reach the nanoscale, with a high aspect ratio. After achieving nanoscale dispersion in composite materials, the larger specific surface area allows for a more complete flame-retardant effect. Furthermore, this invention utilizes sodium phytate and carboxylated carbon nanotubes, doped with cobalt-copper ions, to prepare modified carbon nanotubes. The phytic acid coating improves the interfacial compatibility between the carbon nanotubes and the resin, enabling better dispersion of the carbon nanotubes in the polymer and effectively improving the mechanical properties of the composite material. On the other hand, the phytic acid coating on the modified carbon nanotubes decomposes during heating, producing phosphorus-containing compounds and metal phosphates that help suppress free radicals. The metal phosphates have a catalytic effect, catalyzing the dehydration and crosslinking of nylon 66 upon heating, and synergistically contributing to the gases generated by their own decomposition, constructing a robust, expandable, and porous heat-insulating and oxygen-barrier carbon layer. Simultaneously, the gas-phase free radical capture effect further enhances the flame-retardant effect. In addition, sodium phytate can encapsulate carbon nanotubes with excellent conductivity, hindering electron transport and thus effectively improving the insulation performance of the composite material.

[0013] As a further embodiment of the present invention, the lubricant is at least one of pentaerythritol, ethylene bis-stearamide, polyethylene wax, and calcium stearate.

[0014] As a further aspect of the present invention, the antioxidant includes hindered phenolic antioxidants and phosphite antioxidants. Using a combination of hindered phenolic antioxidants and phosphite antioxidants can improve the stability of nylon processing, while also preventing changes in color and properties, and extending service life.

[0015] As a further aspect of the present invention, the mass ratio of the hindered phenolic antioxidant to the phosphite antioxidant is 1 to 1.8:1.

[0016] In this further embodiment of the invention, the hindered phenolic antioxidant is antioxidant 1010, and the phosphite antioxidant is antioxidant 168.

[0017] A second aspect of the present invention provides a method for preparing a nylon 66 composition, comprising the following steps: Step 1: Weigh each raw material according to the weight parts, add nylon 66 resin, modified ammonium polyphosphate, modified carbon nanotubes, lubricant and antioxidant into a mixer, mix until uniform, and obtain a mixture; Step 2: The mixture obtained in Step 1 is fed into a twin-screw extruder, mixed, melted, extruded and granulated to obtain a Nylon 66 composition.

[0018] As a further embodiment of the present invention, in step 2, the temperature of the twin-screw extruder is 190-200℃ in zone 1, 210-220℃ in zone 2, 220-240℃ in zone 3, 240-250℃ in zone 4, 260-280℃ in zone 5, 270-280℃ in zone 6, and 260-280℃ at the die head.

[0019] The beneficial effects of this invention are: (1) The present invention enhances the flame retardant and mechanical properties of nylon 66 resin by adding modified ammonium polyphosphate and modified carbon nanotubes. After modification, both polyphosphate and carbon nanotubes have good interfacial compatibility with the matrix resin and can be uniformly dispersed in the composite material, thereby effectively enhancing the flame retardant and mechanical properties of nylon 66.

[0020] (2) The modified ammonium polyphosphate added in this invention is modified by silane coupling agent KH-550, which improves the dispersibility of ammonium polyphosphate and enhances its interfacial compatibility with resin. Compared with unmodified ammonium polyphosphate, the introduction of coupling agent KH-550 has a positive effect on the thermal decomposition of ammonium polyphosphate into carbon, resulting in better flame retardant effect and obvious smoke suppression effect. The maximum heat release rate, total heat release, smoke release rate and total smoke release rate all reach the minimum value, effectively playing a role in flame retardancy and smoke suppression of composite materials, and greatly improving the flame retardant performance of nylon 66 composition.

[0021] (3) The modified carbon nanotubes added in this invention have both reinforcing and flame-retardant functions. By co-doping cobalt and copper ions with sodium phytate and carboxylated carbon nanotubes, modified carbon nanotubes with phytic acid coating on the surface are obtained, which improves their interfacial compatibility and dispersibility with the resin, thereby enhancing mechanical properties. When heated, phytic acid decomposes to generate phosphorus-containing compounds and metal phosphates, catalyzing polymer dehydration and cross-linking to form an expanded porous carbon layer, achieving heat insulation, oxygen isolation, and free radical capture, and synergistically exerting a highly efficient flame-retardant effect. At the same time, phytic acid coating inhibits the conductivity of carbon nanotubes, improving the insulation performance of the composite material, so that the Nylon 66 composition has excellent mechanical properties, flame-retardant properties, and insulation properties.

[0022] (4) The method for preparing a nylon 66 composition provided by the present invention is simple to operate, the raw materials are readily available, and it is suitable for large-scale production. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Preparation Example

[0025] Preparation Example 1

[0026] This preparation example provides a carboxylated carbon nanotube, and the preparation steps are as follows: 5g of carbon nanotubes were added to 50mL of concentrated sulfuric acid and 150mL of concentrated nitric acid, and sonicated for 6h. Then the temperature was raised to 80℃ and refluxed for 72h. The mixture was then diluted with deionized water, centrifuged, washed three times with deionized water and anhydrous ethanol, and dried to obtain carboxylated carbon nanotubes.

[0027] Preparation Example 2

[0028] This preparation example provides a modified carbon nanotube, and the preparation steps are as follows: 4.1 g of sodium phytate and 4.0 g of carboxylated carbon nanotubes from Preparation Example 1 were added to 50 mL of deionized water and ultrasonically dispersed until homogeneous to obtain solution A. 3.84 g of cobalt nitrate hexahydrate and 3.18 g of copper nitrate were added to 100 mL of deionized water and stirred until homogeneous to obtain solution B. Solution B was slowly added to solution A and stirred for 0.5 h. Then, the mixture was placed in a reactor at 195 °C and the reaction continued for 12 h. After the reaction was completed, the mixture was filtered, centrifuged, washed, and dried to obtain modified carbon nanotubes.

[0029] Preparation Example 3

[0030] This preparation example provides a modified carbon nanotube, and the preparation steps are as follows: 4.2 g of sodium phytate and 4.1 g of carboxylated carbon nanotubes from Preparation Example 1 were added to 50 mL of deionized water and ultrasonically dispersed until homogeneous to obtain solution A. 3.86 g of cobalt nitrate hexahydrate and 3.20 g of copper nitrate were added to 100 mL of deionized water and stirred until homogeneous to obtain solution B. Solution B was slowly added to solution A and stirred for 1 h. Then, the mixture was placed in a 200 °C reactor and the reaction continued for 12 h. After the reaction was completed, the mixture was filtered, centrifuged, washed, and dried to obtain modified carbon nanotubes.

[0031] Preparation Example 4

[0032] This preparation example provides a modified ammonium polyphosphate, and the preparation steps are as follows: 20g of silane coupling agent KH-550 and 8g of deionized water were added to 72g of anhydrous ethanol, heated to 50℃, and stirred for 0.5h to obtain a hydrolysate of silane coupling agent KH-550. 40g of ammonium polyphosphate and 2.0g of the hydrolysate of silane coupling agent KH-550 were added to 150mL of anhydrous ethanol, heated to 65℃ and stirred for 1.5h. The mixture was then filtered and dried in a vacuum drying oven at 60℃ for 3h to obtain modified ammonium polyphosphate.

[0033] Preparation Example 5

[0034] This preparation example provides a modified ammonium polyphosphate, and the preparation steps are as follows: 20g of silane coupling agent KH-550 and 8g of deionized water were added to 72g of anhydrous ethanol, heated to 55℃, and stirred for 0.5h to obtain a hydrolysate of silane coupling agent KH-550. 42g of ammonium polyphosphate and 2.6g of the hydrolysate of silane coupling agent KH-550 were added to 150mL of anhydrous ethanol, heated to 65℃ and stirred for 1.5h. The mixture was then filtered and dried in a vacuum drying oven at 60℃ for 3h to obtain modified ammonium polyphosphate.

[0035] Example

[0036] Example 1

[0037] This embodiment provides a nylon 66 composition and its preparation method: A nylon 66 composition, by weight, comprises the following components: 100 parts of nylon 66 resin, 3 parts of modified ammonium polyphosphate from Preparation Example 4, 5 parts of modified carbon nanotubes from Preparation Example 2, 0.1 parts of polyethylene wax, and 0.1 parts of antioxidant; The antioxidant is composed of antioxidant 1010 and antioxidant 168 in a mass ratio of 1.1:1.

[0038] A method for preparing a nylon 66 composition includes the following steps: Step 1: Weigh each raw material according to the weight parts, add nylon 66 resin, modified ammonium polyphosphate, modified carbon nanotubes, polyethylene wax and antioxidant into a mixer, mix until uniform, and obtain a mixture; Step 2: The mixture obtained in Step 1 is fed into a twin-screw extruder. The temperature of the twin-screw extruder is 190℃ in Zone 1, 210℃ in Zone 2, 220℃ in Zone 3, 240℃ in Zone 4, 260℃ in Zone 5, 270℃ in Zone 6, and 260℃ at the die head. After mixing, melting, extrusion and granulation, a nylon 66 composition is obtained.

[0039] Example 2

[0040] The only difference from Example 1 is that: The modified ammonium polyphosphate in Preparation Example 4 was replaced with the modified ammonium polyphosphate in Preparation Example 5, with the amount of each component remaining the same.

[0041] Example 3

[0042] The only difference from Example 1 is that: The modified carbon nanotubes in Preparation Example 2 were replaced with the modified carbon nanotubes in Preparation Example 3, with the same amount of each component.

[0043] Example 4

[0044] The only difference from Example 1 is that: The modified ammonium polyphosphate in Preparation Example 4 was replaced with the modified ammonium polyphosphate in Preparation Example 5, and the modified carbon nanotubes in Preparation Example 2 were replaced with the modified carbon nanotubes in Preparation Example 3, with the amounts remaining the same.

[0045] Example 5

[0046] The only difference from Example 1 is the amount of raw material components used: A nylon 66 composition, by weight, comprises the following components: 100 parts of nylon 66 resin, 4 parts of modified ammonium polyphosphate in Preparation Example 4, 8 parts of modified carbon nanotubes in Preparation Example 2, 0.18 parts of polyethylene wax, and 0.2 parts of antioxidant.

[0047] Example 6

[0048] The only difference from Example 1 is the amount of raw material components used: A nylon 66 composition, by weight, comprises the following components: 100 parts of nylon 66 resin, 5 parts of modified ammonium polyphosphate in Preparation Example 4, 10 parts of modified carbon nanotubes in Preparation Example 2, 0.28 parts of polyethylene wax, and 0.5 parts of antioxidant.

[0049] Example 7

[0050] The only difference from Example 1 is the amount of antioxidant component used: The antioxidant is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1.7:1.

[0051] Example 8

[0052] The only difference from Example 1 is that the process parameters in step 2 are different: A method for preparing a nylon 66 composition includes the following steps: Step 1: Weigh each raw material according to the weight parts, add nylon 66 resin, modified ammonium polyphosphate, modified carbon nanotubes, polyethylene wax and antioxidant into a mixer, mix until uniform, and obtain a mixture; Step 2: The mixture obtained in Step 1 is fed into a twin-screw extruder. The temperature of the twin-screw extruder is 195℃ in Zone 1, 215℃ in Zone 2, 230℃ in Zone 3, 245℃ in Zone 4, 268℃ in Zone 5, 273℃ in Zone 6, and 267℃ at the die head. After mixing, melting, extrusion and granulation, a nylon 66 composition is obtained.

[0053] Example 9

[0054] The only difference from Example 1 is that the process parameters in step 2 are different: A method for preparing a nylon 66 composition includes the following steps: Step 1: Weigh each raw material according to the weight parts, add nylon 66 resin, modified ammonium polyphosphate, modified carbon nanotubes, polyethylene wax and antioxidant into a mixer, mix until uniform, and obtain a mixture; Step 2: The mixture obtained in Step 1 is fed into a twin-screw extruder. The temperature of the twin-screw extruder is 200℃ in Zone 1, 218℃ in Zone 2, 235℃ in Zone 3, 247℃ in Zone 4, 280℃ in Zone 5, 280℃ in Zone 6, and 280℃ at the die head. After mixing, melting, extrusion and granulation, a nylon 66 composition is obtained.

[0055] Comparative Example

[0056] Comparative Example 1

[0057] The only difference from Example 1 is that: A nylon 66 composition, by weight, comprises the following components: 100 parts nylon 66 resin, 3 parts ammonium polyphosphate, 5 parts carbon nanotubes, 0.1 parts polyethylene wax, and 0.1 parts antioxidant.

[0058] Comparative Example 2

[0059] The only difference from Example 1 is that: A nylon 66 composition, by weight, comprises the following components: The mixture consisted of 100 parts nylon 66 resin, 3 parts modified ammonium polyphosphate (as in Preparation Example 4), 5 parts carbon nanotubes, 0.1 parts polyethylene wax, and 0.1 parts antioxidant. Comparative Example 3 The only difference from Example 1 is that: A nylon 66 composition, by weight, comprises the following components: 100 parts nylon 66 resin, 3 parts ammonium polyphosphate, 5 parts modified carbon nanotubes from Preparation Example 2, 0.1 parts polyethylene wax, and 0.1 parts antioxidant. Comparative Example 4 The only difference from Example 1 is that: Replace 3 parts of the modified polyphosphate in Preparation Example 4 with 1.5 parts of the modified polyphosphate in Preparation Example 4.

[0060] Comparative Example 5

[0061] The only difference from Example 6 is that: The 5 parts of modified polyphosphate in Preparation Example 4 were replaced with 6.3 parts of modified polyphosphate in Preparation Example 4.

[0062] Comparative Example 6

[0063] The only difference from Example 1 is that: The 5 parts of modified carbon nanotubes in Preparation Example 2 were replaced with 3.8 parts of modified carbon nanotubes in Preparation Example 2.

[0064] Comparative Example 7

[0065] The only difference from Example 6 is that: The 10 parts of modified carbon nanotubes in Preparation Example 2 were replaced with 12 parts of modified carbon nanotubes in Preparation Example 2.

[0066] Comparative Example 8

[0067] The only difference from Example 1 is the amount of raw material components used: A nylon 66 composition, by weight, comprises the following components: 86 parts of nylon 66 resin, 3 parts of modified ammonium polyphosphate in Preparation Example 4, 5 parts of modified carbon nanotubes in Preparation Example 2, 0.1 parts of polyethylene wax, and 0.1 parts of antioxidant.

[0068] Comparative Example 9

[0069] The only difference from Example 1 is the amount of raw material components used: A nylon 66 composition, by weight, comprises the following components: 86 parts of nylon 66 resin, 1 part of modified ammonium polyphosphate from Preparation Example 4, 5 parts of modified carbon nanotubes from Preparation Example 2, and 0.1 parts of antioxidant; Comparative Example 10 The only difference from Example 1 is that the process parameters in step 2 are different: A method for preparing a nylon 66 composition includes the following steps: Step 1: Weigh each raw material according to the weight parts, add nylon 66 resin, modified ammonium polyphosphate, modified carbon nanotubes, polyethylene wax and antioxidant into a mixer, mix until uniform, and obtain a mixture; Step 2: The mixture obtained in Step 1 is fed into a twin-screw extruder. The temperature of the twin-screw extruder is 170℃ in Zone 1, 200℃ in Zone 2, 220℃ in Zone 3, 240℃ in Zone 4, 260℃ in Zone 5, 260℃ in Zone 6, and 250℃ at the die head. After mixing, melting, extrusion and granulation, a nylon 66 composition is obtained.

[0070] Comparative Example 10

[0071] The only difference from Example 1 is that the process parameters in step 2 are different: A method for preparing a nylon 66 composition includes the following steps: Step 1: Weigh each raw material according to the weight parts, add nylon 66 resin, modified ammonium polyphosphate, modified carbon nanotubes, polyethylene wax and antioxidant into a mixer, mix until uniform, and obtain a mixture; Step 2: The mixture obtained in Step 1 is fed into a twin-screw extruder. The temperature of the twin-screw extruder is 180℃ in Zone 1, 210℃ in Zone 2, 210℃ in Zone 3, 220℃ in Zone 4, 250℃ in Zone 5, 255℃ in Zone 6, and 255℃ at the die head. After mixing, melting, extrusion and granulation, a nylon 66 composition is obtained.

[0072] Performance testing

[0073] The following performance tests were performed on the nylon 66 compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 10: (1) Mechanical properties: The ASTM standard injection molding was adopted. The dimensions of the specimen (length × width × thickness) are as follows: The specimens used for tensile strength and flexural strength testing are dumbbell-shaped, 170mm × 13mm × 3.2mm.

[0074] 1. Tensile strength was tested according to ASTM D638 at a tensile speed of 5 mm / min.

[0075] 2. Bending strength was tested according to ASTM D790, with a bending speed of 1.25 mm / min.

[0076] (2) The flame retardant performance was tested according to the UL-94 standard, with a sample thickness of 1.6 mm.

[0077] The test results are shown in Table 1: Table 1

[0078] As can be seen from Table 1, the tensile strength, flexural strength, flame retardancy rating and limiting oxygen index of the nylon 66 compositions prepared in Examples 1 to 9 are all better than those of the nylon 66 compositions prepared in Comparative Examples 1 to 10. Therefore, the nylon 66 composition provided by the present invention has excellent mechanical properties and flame retardant properties.

[0079] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0080] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A nylon 66 composition, characterized in that, By weight, it includes the following components: 100 parts of Nylon 66 resin; 3-5 parts of modified ammonium polyphosphate; 5-10 parts of modified carbon nanotubes; Lubricant 0.10–0.28 parts; Antioxidant 0.1–0.5 parts; The modified ammonium polyphosphate is prepared through the following steps: Add silane coupling agent KH-550 and deionized water to anhydrous ethanol, heat to 50-55℃, and stir for 0.5-1.0 h to obtain a hydrolysate of silane coupling agent KH-550. Add ammonium polyphosphate and the hydrolysate of silane coupling agent KH-550 to anhydrous ethanol, heat to 60-65℃ and stir for 1.0-1.5 h, filter, and vacuum dry to obtain modified ammonium polyphosphate.

2. The nylon 66 composition according to claim 1, characterized in that, The ratio of silane coupling agent KH-550, deionized water and anhydrous ethanol is 20g:8g:72g; the ratio of ammonium polyphosphate, hydrolysate of silane coupling agent KH-550 and anhydrous ethanol is 40-42g:2.0-2.6g:150mL.

3. The nylon 66 composition according to claim 1, characterized in that, The modified carbon nanotubes are prepared through the following steps: Sodium phytate and carboxylated carbon nanotubes were added to deionized water and ultrasonically dispersed until homogeneous to obtain solution A. Cobalt nitrate hexahydrate and copper nitrate were added to the deionized water solution and stirred until homogeneous to obtain solution B. Solution B was slowly added to solution A and stirred for 0.5–1 h. Then, the mixture was placed in a reactor at 195–200 °C and the reaction was continued for 12–14 h. After the reaction was completed, the mixture was filtered, centrifuged, washed, and dried to obtain modified carbon nanotubes.

4. The nylon 66 composition according to claim 3, characterized in that, In solution A, the ratio of sodium phytate, carboxylated carbon nanotubes, and deionized water is 4.1–4.2 g: 4.0–4.1 g: 50 mL; in solution B, the ratio of cobalt nitrate hexahydrate, copper nitrate, and deionized water is 3.84–3.86 g: 3.18–3.20 g: 100 mL.

5. The nylon 66 composition according to claim 1, characterized in that, The lubricant is at least one of pentaerythritol, ethylene bis-stearamide, polyethylene wax, and calcium stearate.

6. The nylon 66 composition according to claim 1, characterized in that, The antioxidants include hindered phenolic antioxidants and phosphite antioxidants.

7. A nylon 66 composition according to claim 6, characterized in that, The mass ratio of the hindered phenolic antioxidant to the phosphite antioxidant is 1 to 1.8:

1.

8. A nylon 66 composition according to claim 6, characterized in that, The hindered phenolic antioxidant is antioxidant 1010, and the phosphite antioxidant is antioxidant 168.

9. The method for preparing a nylon 66 composition according to claim 1, characterized in that, Includes the following steps: Step 1: Weigh each raw material according to the weight parts, add nylon 66 resin, modified ammonium polyphosphate, modified carbon nanotubes, lubricant and antioxidant into a mixer, mix until uniform, and obtain a mixture; Step 2: The mixture obtained in Step 1 is fed into a twin-screw extruder, mixed, melted, extruded and granulated to obtain a Nylon 66 composition.

10. The method for preparing a nylon 66 composition according to claim 9, characterized in that, In step 2, the temperature of the twin-screw extruder is 190-200℃ in zone 1, 210-220℃ in zone 2, 220-240℃ in zone 3, 240-250℃ in zone 4, 260-280℃ in zone 5, 270-280℃ in zone 6, and 260-280℃ at the die head.

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