Ultra-dispersed flame-retardant engineering plastic master batch and preparation method thereof

Abstract

The invention discloses an ultra-dispersed flame-retardant engineering plastic master batch and a preparation method thereof, and relates to the technical field of functional plastics. The functional master batch is prepared from the following components in parts by weight: 100 parts of a nylon 6 sheet, 0.5 to 8 parts of a modified carbon nano tube, 5 to 15 parts of diethyl phosphinated ethyl aluminum phosphite, 5 to 15 parts of a flame retardant, 2 to 5 parts of a carbon forming agent, 0.5 to 5 parts of epoxy silicon dioxide and 0.5 to 5 parts of a compatilizer. According to the flame-retardant plastic master batch disclosed by the invention, by introducing the diethyl phosphinated ethyl aluminum phosphite and the flame retardant, a carbon layer and a Schiff base structure are formed on the surface of a material when the plastic master batch is combusted, so that the interaction force between molecular chains of the plastic master batch is improved, the dual properties of flame retardance and molten drop resistance of the plastic master batch are improved, and the problem of fire spreading caused by molten drops is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of functional plastics, and specifically relates to a super-dispersed flame-retardant engineering plastic masterbatch and a preparation method thereof. Background Art

[0002] With the development of modern industry, people's requirements for material properties are increasing day by day. Polyamide 6 (PA6), as a widely used engineering plastic, has excellent mechanical properties, wear resistance, chemical corrosion resistance, and good processing performance, and is widely used in fields such as automobiles, electronic appliances, and aerospace. However, in actual production and application, PA6 is a flammable material, and melt dripping is likely to occur during the combustion process.

[0003] When PA6 burns, there is a phenomenon of molten dripping. These high-temperature liquid substances adhere to the surface of combustibles, which may cause secondary combustion and lead to the spread of fire. At the same time, the high volume resistivity of PA6 makes it easy to accumulate static electricity, increasing the risk of fire and explosion.

[0004] Patent CN114854194B discloses a flame-retardant plastic masterbatch and a preparation method thereof. The above patent realizes good compatibility between various raw materials, improves the compatibility between various components, improves the product stability of the flame-retardant plastic masterbatch, and the flame-retardant components synergistically improve the flame-retardant effect.

[0005] The above patent reduces the interfacial difference between inorganic raw materials and organic raw materials, and solves the problem of poor compatibility between the flame retardant and the polymer. However, there is still room for optimization in the anti-melt dripping performance of the plastic masterbatch. The present application prepares a plastic masterbatch with excellent anti-melt dripping performance and high flame-retardant performance, and solves the problem of secondary combustion caused by melt dripping of engineering plastics.

[0006] Therefore, the present application proposes a super-dispersed flame-retardant engineering plastic masterbatch and a preparation method thereof that achieve both excellent anti-melt dripping performance and high flame-retardant performance. Summary of the Invention

[0007] The purpose of the present invention is to provide a super-dispersed flame-retardant engineering plastic masterbatch and a preparation method thereof, so as to solve the technical problem of secondary combustion caused by melt dripping of engineering plastics proposed in the above background art.

[0008] To achieve the above purpose, the present invention provides the following technical solution: A super-dispersed flame-retardant engineering plastic masterbatch includes a functional masterbatch. The functional masterbatch includes the following components by weight: 100 parts of nylon 6 sheet, 0.5 - 8 parts of modified carbon nanotubes, 5 - 15 parts of aluminum ethyl bis(ethylphosphinate), 5 - 15 parts of flame retardant, 2 - 5 parts of charring agent, 0.5 - 5 parts of epoxidized silica, 0.5 - 5 parts of compatibilizer. The preparation method of the aluminum ethyl bis(ethylphosphinate) includes the following steps: Dissolve aluminum sulfate in deionized water to prepare a metal salt solution. Heat the metal salt solution to 50 °C, and slowly drop the mixture of diethyl phosphinic acid and ethyl phosphonous acid into the metal salt solution, and stir for 1 h; Cool to room temperature, filter, wash, and dry. Crush the dried product to obtain aluminum ethyl phosphonite diethylphosphinate.

[0009] Preferably, the preparation method of the charring agent comprises the following steps: Dissolve enzymatically hydrolyzed lignin in N,N-dimethylformamide solution, sequentially add triglycidyl isocyanurate, aminotrimethylenephosphonic acid, and benzoic acid, and perform ethanol elution, drying, and crushing to obtain the charring agent.

[0010] Preferably, the preparation method of the flame retardant comprises the following steps: Mix benzoguanamine and p-methoxybenzaldehyde and add them to toluene. Add p-toluenesulfonic acid, stir evenly, and heat to 110 °C for condensation reflux to obtain a reactant; Use a suction filtration device to filter off the liquid part of the reactant to obtain a solid product. Wash the solid product with absolute ethanol, and place the washed solid product in an oven at 50 °C for drying to obtain the flame retardant.

[0011] Preferably, the preparation method of the modified carbon nanotubes comprises the following steps: Disperse carbon nanotubes in a mixed solution of deionized water and ethanol, add spirocyclic pentaerythritol bisphosphate, and use an ultrasonic disperser for dispersion treatment. Heat to 80 °C and stir for 10 h to obtain a suspension; Filter and wash the suspension. Place the filtered product in an oven and dry at 80 °C for 12 h. Grind the dried product to obtain modified carbon nanotubes.

[0012] Preferably, the preparation method of the spirocyclic pentaerythritol bisphosphate comprises the following steps: Mix phosphorus oxychloride and pentaerythritol and add them to a reaction vessel. Heat to 100 °C and stir, and perform filtration, washing, and vacuum distillation to obtain spirocyclic pentaerythritol bisphosphate dichloride; Dissolve spirocyclic pentaerythritol bisphosphate dichloride and triethylamine in acetonitrile, drop into a mixed solution of 3-aminopropyltriethoxysilane and acetonitrile, stir at 40 °C for 10 h, and perform filtration and vacuum distillation to obtain spirocyclic pentaerythritol bisphosphate.

[0013] Preferably, the preparation method of the compatibilizer comprises the following steps: Epichlorohydrin was slowly added dropwise to the hexamethylenediamine solution, and the reaction was carried out at 70 °C for 2 h. Then, vacuum dehydration and drying treatments were performed to obtain a polar polymer. The polar polymer and maleic anhydride-grafted polypropylene were added to xylene, and the reaction was carried out at 120 °C for 8 h. Then, ethanol washing, filtration, and drying treatments were performed to obtain an intermediate product. The intermediate product was added to xylene, and the temperature was raised to 100 °C. Modified graphene oxide and butylammonium bromide were successively added, and the reaction was carried out at 120 °C for 8 h. Then, filtration, drying, and grinding treatments were performed to obtain a compatibilizer.

[0014] Preferably, the epoxidized silica is prepared by modifying silica with 3-glycidoxypropyltrimethoxysilane and n-octyltriethoxysilane.

[0015] Preferably, the modified graphene oxide is prepared by modifying graphene oxide with 2,3-epoxypropyltrimethylammonium chloride.

[0016] Preferably, the preparation method includes the following steps: S1. Nylon 6 sheets, modified carbon nanotubes, aluminum ethyl bis(ethylphosphinate), a flame retardant, a charring agent, epoxidized silica, and a compatibilizer were mixed using a high-speed mixer to obtain a mixed material. S2. The mixed material was fed into the feeding port of a twin-screw extruder. The temperature of the extruder was set at 210-250 °C. After water-cooled strand pelletizing, the pellets were placed in an oven and dried at 120 °C for 10 h to obtain a functional masterbatch.

[0017] Preferably, the preparation method further includes the following steps: S11. The nylon 6 sheets were placed in an oven and dried at 120 °C for 10 h.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By introducing aluminum ethyl bis(ethylphosphinate) and a flame retardant, a carbon layer is formed on the surface of the plastic masterbatch during combustion. The Schiff base structure improves the intermolecular force between the molecular chains of the plastic masterbatch, realizing the dual performance improvement of flame retardancy and anti-dripping of the plastic masterbatch and solving the problem of the spread of fire caused by dripping. 2. By introducing a lignin-based charring agent and jointly acting with phosphorus-containing aluminum ethyl bis(ethylphosphinate) and nitrogen- and phosphorus-containing flame retardants, an efficient flame retardant system containing carbon, nitrogen, and phosphorus elements is formed, further improving the flame retardant effect of the plastic masterbatch and improving the overall flame retardant performance of the functional masterbatch. 3. By introducing modified carbon nanotubes, a conductive network is formed in the plastic masterbatch, achieving an improvement in the antistatic property of the functional masterbatch, promoting the rapid release of charges, effectively suppressing the accumulation and discharge of static electricity in the plastic masterbatch, solving the problem of static electricity causing sparks to ignite itself or surrounding combustibles, and ensuring the safety of the plastic masterbatch production and use processes; 4. By introducing a compatibilizer containing graphene oxide nanosheets, the interfacial tension between the components is reduced, the interaction force between the components of the functional masterbatch is enhanced, and the compatibility and stability between the components of the plastic masterbatch are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the preparation process of the functional masterbatch of the present invention; Figure 2 It is a schematic diagram of the preparation process of aluminum ethyl phosphinate bis(ethylphosphonate) of the present invention; Figure 3 It is a schematic diagram of the preparation process of the charring agent of the present invention; Figure 4 It is a schematic diagram of the preparation process of the flame retardant of the present invention; Figure 5 It is a schematic diagram of the preparation process of the modified carbon nanotubes of the present invention; Figure 6 It is a schematic diagram of the preparation process of spirocyclic pentaerythritol bis(dichlorophosphate) of the present invention; Figure 7 It is a schematic diagram of the preparation process of spirocyclic pentaerythritol bis(phosphate) of the present invention; Figure 8 It is a schematic diagram of the preparation process of the compatibilizer of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] Example 1, please refer to Figure 1 and Figure 2 , a preparation method of a super-dispersed flame-retardant engineering plastic masterbatch, the preparation method comprising the following steps: Dissolve aluminum sulfate in deionized water to prepare a metal salt solution. Heat the metal salt solution to 50°C, slowly drop a mixture of diethyl phosphinic acid and ethyl phosphorous acid into the metal salt solution, stir for 1 h, cool to room temperature, perform filtration, washing, and drying treatments, and pulverize the dried product to obtain aluminum ethyl phosphinate bis(ethylphosphonate); Using a high-speed mixer, 100 parts of nylon 6 sheet, 8 parts of modified carbon nanotubes, 15 parts of aluminum ethyl bis(diethylphosphinate), 15 parts of flame retardant, 5 parts of charring agent, 5 parts of epoxy silica, and 5 parts of compatibilizer were mixed to obtain a mixed material; The mixed material was fed into the feeding port of a twin-screw extruder. The temperature of the extruder was set at 210 - 250 °C. After water-cooled strand pelletization, the produced pellets were placed in an oven and dried at 120 °C for 10 h to obtain the functional masterbatch.

[0022] Furthermore, as a double salt, during the crystal formation process of aluminum ethyl bis(diethylphosphinate), aluminum ions combine with diethylphosphinate and ethylphosphonate ions simultaneously to form a crystal structure with a hydrophobic end. As a result, aluminum ethyl bis(diethylphosphinate) is likely to produce small crystals in the reaction system and is not easy to grow into large crystals, thereby improving the dispersibility and stability of aluminum ethyl bis(diethylphosphinate) when blended with other materials and enhancing the dispersion effect of the materials. In addition, aluminum ethyl bis(diethylphosphinate) has excellent flame retardant properties, thus improving the thermal stability of the functional masterbatch. It can promote the formation of an expanded carbon layer in the polymer during combustion, effectively blocking the transfer of oxygen and heat, slowing down the combustion speed, and preventing further combustion. When the functional masterbatch burns, aluminum ethyl bis(diethylphosphinate) decomposes upon heating to produce products such as water vapor and aluminum phosphate, which can effectively absorb the heat in the combustion area and dilute the combustible gas, preventing the further spread of the flame. Moreover, after being mixed with components such as flame retardants and charring agents, aluminum ethyl bis(diethylphosphinate) can exert a synergistic flame retardant effect, further enhancing the flame retardant performance of the materials.

[0023] Example 2, please refer to Figure 1 and Figure 3 , a preparation method of a super-dispersed flame retardant engineering plastic masterbatch, the preparation method comprising the following steps: The enzymatically hydrolyzed lignin was dissolved in an N,N-dimethylformamide solution. Triglycidyl isocyanurate, aminotrimethylene phosphonic acid, and benzoic acid were added in sequence, followed by ethanol elution, drying, and pulverization to obtain the charring agent; Using a high-speed mixer, 100 parts of nylon 6 sheet, 6 parts of modified carbon nanotubes, 12 parts of aluminum ethyl bis(diethylphosphinate), 12 parts of flame retardant, 4 parts of charring agent, 4 parts of epoxy silica, and 4 parts of compatibilizer were mixed to obtain a mixed material; The mixed material was fed into the feeding port of a twin-screw extruder. The temperature of the extruder was set at 210 - 250 °C. After water-cooled strand pelletization, the produced pellets were placed in an oven and dried at 120 °C for 10 h to obtain the functional masterbatch.

[0024] Furthermore, by enzymatically hydrolyzing lignin to prepare a carbon agent, a lignin-based carbon agent is obtained. The aromatic ring structure in the lignin molecule enables lignin to decompose to produce a stable carbon layer under high-temperature conditions, thereby forming a dense carbon layer during the combustion process, further preventing heat transfer and blocking oxygen, slowing down the combustion process. Thus, when the functional masterbatch burns, the presence of the carbon layer can reduce the burning rate of the functional masterbatch, prevent the spread of fire, and further improve the flame retardancy of the functional masterbatch; the lignin-based carbon agent provides a carbon source for the flame retardant system of the functional masterbatch. When it acts together with aluminum ethyl phosphite diethylphosphinate containing phosphorus and a flame retardant containing nitrogen and phosphorus, the three elements of carbon, nitrogen, and phosphorus act synergistically to form an efficient flame retardant system. Aluminum ethyl phosphite diethylphosphinate decomposes to produce a phosphate structure, providing an acid source and a gas source for the flame retardant process, while the lignin-based carbon agent provides a carbon source, thereby further improving the flame retardant effect and enhancing the overall flame retardancy of the functional masterbatch.

[0025] Example 3, please refer to Figure 1 and Figure 4 , a preparation method of a super-dispersed flame retardant engineering plastic masterbatch, the preparation method comprising the following steps: Mix benzoguanamine and p-methoxybenzaldehyde, add them to toluene, add p-toluenesulfonic acid, stir evenly, heat to 110 °C, carry out condensation reflux treatment to obtain a reactant, use a suction filtration device to filter out the liquid part of the reactant to obtain a solid product, wash the solid product with absolute ethanol, and place the washed solid product in an oven at 50 °C for drying treatment to obtain a flame retardant; Use a high-speed mixer to mix 100 parts of nylon 6 sheet, 5 parts of modified carbon nanotubes, 10 parts of aluminum ethyl phosphite diethylphosphinate, 10 parts of flame retardant, 3 parts of carbon agent, 3 parts of epoxy silica, and 3 parts of compatibilizer to obtain a mixture; Feed the mixture into the feeding port of a twin-screw extruder, set the temperature of the extruder to 210 - 250 °C, carry out water-cooled strand pelletizing, put the pellets into an oven, and dry at 120 °C for 10 h to obtain a functional masterbatch.

[0026] Furthermore, the flame retardant is a flame retardant with a s-triazine ring and Schiff base structure. During the combustion process, the s-triazine ring structure can expand into carbon, thus forming a dense carbonaceous layer on the material surface, effectively isolating the transfer of heat, oxygen, and combustible gases, slowing down the combustion speed, and improving the flame retardant performance of the functional masterbatch. The s-triazine ring structure decomposes upon heating and releases gases such as water vapor and carbon dioxide. These gases cause the volume of the functional masterbatch to expand, forming a porous carbonaceous protective layer and slowing down the combustion process. At the same time, the Schiff base structure can undergo an irreversible chemical cross-linking reaction at high temperatures, forming a stable cross-linking network. The cross-linking effect enhances the intermolecular forces between the molecular chains of the functional masterbatch, making it difficult for the functional masterbatch to melt and drip during combustion, avoiding the spread of fire caused by molten droplets during the combustion of the functional masterbatch, and thus improving the anti-melting and dripping performance of the functional masterbatch. The synergistic effect of the flame retardant, char-forming agent, and aluminum ethyl bis(ethylphosphinate) enables the functional masterbatch to have excellent flame retardant performance while also having excellent anti-melting and dripping performance, achieving a double improvement in the flame retardant and anti-melting and dripping properties of the functional masterbatch.

[0027] Example 4, please refer to Figure 1 、 Figure 5 、 Figure 6 and Figure 7 , a preparation method of a super-dispersed flame retardant engineering plastic masterbatch, the preparation method comprising the following steps: Phosphorus oxychloride and pentaerythritol are mixed and then added to a reaction vessel, heated to 100 °C and stirred, filtered, washed, and subjected to vacuum distillation to obtain spiro pentaerythritol bisphosphate dichloride. Spiro pentaerythritol bisphosphate dichloride and triethylamine are dissolved in acetonitrile, and a mixed solution of 3-aminopropyltriethoxysilane and acetonitrile is dropped in, stirred at 40 °C for 10 h, filtered, and subjected to vacuum distillation to obtain spiro pentaerythritol bisphosphate; Carbon nanotubes are dispersed in a mixed solution of deionized water and ethanol, spiro pentaerythritol bisphosphate is added, and ultrasonic dispersion treatment is carried out using an ultrasonic disperser, heated to 80 °C, and stirred for 10 h to obtain a suspension. The suspension is filtered and washed, the filtered product is placed in an oven, dried at 80 °C for 12 h, and the dried product is ground to obtain modified carbon nanotubes; Using a high-speed mixer, 100 parts of nylon 6 sheet, 4 parts of modified carbon nanotubes, 8 parts of aluminum ethyl bis(ethylphosphinate), 8 parts of flame retardant, 2 parts of char-forming agent, 2 parts of epoxy silicon dioxide, and 2 parts of compatibilizer are mixed to obtain a mixed material; The mixed material is fed into the feeding port of a twin-screw extruder, the temperature of the extruder is set at 210 - 250 °C, water-cooled strand pelletizing is carried out, and the pellets are placed in an oven and dried at 120 °C for 10 h to obtain the functional masterbatch.

[0028] Furthermore, the carbon nanotubes are graft-modified with spiro pentaerythritol bisphosphate, so that the compatibility between the modified carbon nanotubes and other components of the functional masterbatch is better, the dispersibility of the modified carbon nanotubes in the functional masterbatch is improved, and the modified carbon nanotubes are dispersed in the functional masterbatch, thereby forming a conductive network inside the functional masterbatch, reducing the resistivity of the functional masterbatch, improving the antistatic property of the functional masterbatch, effectively inhibiting the accumulation and discharge of static electricity, thereby avoiding the generation of sparks caused by the failure to transfer the charges generated during the friction of the functional masterbatch in time, preventing the static charges accumulated on the surface of the functional masterbatch from insulating and breaking down the air, solving the problem that the sparks generated by static electricity ignite itself or ignite surrounding combustibles, reducing the occurrence of fires, solving the problem that PA6 is prone to accumulate static electricity, effectively reducing the surface resistivity of the material, reducing the accumulation and discharge of static electricity, and improving the safety during use; In addition, the phosphorus element in the spiro pentaerythritol bisphosphate molecule participates in the formation of a stable carbon layer during combustion, thereby slowing down the combustion speed of the functional masterbatch and improving the flame retardant performance of the functional masterbatch.

[0029] Example 5, please refer to Figure 1 and Figure 8 , a preparation method of a super-dispersed flame-retardant engineering plastic masterbatch, the preparation method comprising the following steps: Epichlorohydrin is slowly added dropwise to the hexamethylenediamine solution, and the reaction is carried out at 70 °C for 2 h, followed by vacuum dehydration and drying treatment to obtain a polar polymer. The polar polymer and maleic anhydride-grafted polypropylene are added to xylene, and the reaction is carried out at 120 °C for 8 h, followed by ethanol washing, filtration, and drying treatment to obtain an intermediate product. The intermediate product is added to xylene, the temperature is raised to 100 °C, modified graphene oxide and butyl ammonium bromide are added in sequence, and the reaction is carried out at 120 °C for 8 h, followed by filtration, drying, and grinding treatment to obtain a compatibilizer; Using a high-speed mixer, 100 parts of nylon 6 sheet, 2 parts of modified carbon nanotubes, 6 parts of aluminum ethyl bisphosphinate, 6 parts of flame retardant, 1 part of carbon-forming agent, 1 part of epoxy silica, and 1 part of compatibilizer are mixed to obtain a mixture; The mixture is fed from the feed port of a twin-screw extruder, the temperature of the extruder is set at 210-250 °C, and it is granulated by water-cooled strand pelletizing. The pellets are placed in an oven and dried at 120 °C for 10 h to obtain a functional masterbatch.

[0030] Furthermore, by introducing a composite compatibilizer, the interaction force between the components of the functional masterbatch is enhanced, thereby improving the compatibility between the components of the functional masterbatch, improving the dispersibility of components such as carbon nanotubes, flame retardants, and charring agents in the matrix nylon 6 sheet, and improving the interfacial bonding force between each component and the matrix nylon 6 sheet. The polymer chains in the composite compatibilizer can entangle with the polymer chains in the functional masterbatch matrix to form a tight network structure, thereby enhancing the interaction force between the components of the functional masterbatch and improving the compatibility and stability of the material; by introducing a compatibilizer containing graphene oxide nanosheets, the interfacial tension between the components is reduced, so that each component is uniformly dispersed. At the same time, the nanosheets have a high specific surface area and surface energy, so they have a strong interaction with the polymer chains in the matrix nylon 6 sheet.

[0031] Example 6, please refer to Figure 1 , a preparation method of a super-dispersed flame-retardant engineering plastic masterbatch, the preparation method comprising the following steps: Dissolve aluminum sulfate in deionized water to prepare a metal salt solution. Heat the metal salt solution to 50°C, slowly drop a mixture of diethyl phosphinic acid and ethyl phosphorous acid into the metal salt solution, stir for 1 h, cool to room temperature, perform filtration, washing, and drying treatments, and pulverize the dried product to obtain aluminum ethylphosphinate bis(diethylphosphinate). Use a high-speed mixer to mix 100 parts of nylon 6 sheet, 0.5 part of modified carbon nanotubes, 5 parts of aluminum ethylphosphinate bis(diethylphosphinate), 5 parts of flame retardant, 0.5 part of charring agent, 0.5 part of epoxidized silica, and 0.5 part of compatibilizer to obtain a mixture. Feed the mixture into the feeding port of a twin-screw extruder. Set the temperature of the extruder to 210 - 250°C, perform water-cooled strand pelletization, put the produced pellets into an oven, and dry at 120°C for 10 h to obtain the functional masterbatch.

[0032] Furthermore, epoxidized silica introduces functional groups epoxy groups and alkoxy groups, and these functional groups can interact with the functional groups in other components such as nylon 6 sheet, flame retardant, and charring agent, thereby improving the compatibility between the functional masterbatches and improving the dispersion uniformity of each component in the functional masterbatch. The modified nano-silica has good wettability and dispersibility, and thus can effectively fill the interfacial region between each component.

[0033] Comparative Example 1, a preparation method of a super-dispersed flame-retardant engineering plastic masterbatch, the preparation method comprising the following steps: Use a high-speed mixer to mix 100 parts of nylon 6 sheet, 8 parts of modified carbon nanotubes, 15 parts of flame retardant, 5 parts of charring agent, 5 parts of epoxidized silica, and 5 parts of compatibilizer to obtain a mixture. Feed the mixture into the feeding port of the twin-screw extruder. Set the temperature of the extruder to 210 - 250 °C. After water-cooled strand pelletizing, put the made pellets into an oven and dry them at 120 °C for 10 h to obtain the functional masterbatch.

[0034] Comparative Example 2, a preparation method of a super-dispersed flame-retardant engineering plastic masterbatch, the preparation method comprising the following steps: Use a high-speed mixer to mix 100 parts of nylon 6 sheet, 8 parts of modified carbon nanotubes, 15 parts of aluminum ethyl phosphinate bis(ethyl phosphite), 15 parts of flame retardant, 5 parts of epoxy silica, and 5 parts of compatibilizer to obtain a mixture; Feed the mixture into the feeding port of the twin-screw extruder. Set the temperature of the extruder to 210 - 250 °C. After water-cooled strand pelletizing, put the made pellets into an oven and dry them at 120 °C for 10 h to obtain the functional masterbatch.

[0035] Comparative Example 3, a preparation method of a super-dispersed flame-retardant engineering plastic masterbatch, the preparation method comprising the following steps: Use a high-speed mixer to mix 100 parts of nylon 6 sheet, 8 parts of modified carbon nanotubes, 15 parts of aluminum ethyl phosphinate bis(ethyl phosphite), 5 parts of charring agent, 5 parts of epoxy silica, and 5 parts of compatibilizer to obtain a mixture; Feed the mixture into the feeding port of the twin-screw extruder. Set the temperature of the extruder to 210 - 250 °C. After water-cooled strand pelletizing, put the made pellets into an oven and dry them at 120 °C for 10 h to obtain the functional masterbatch.

[0036] Comparative Example 4 A preparation method of a super-dispersed flame-retardant engineering plastic masterbatch, the preparation method comprising the following steps: Mix phosphorus oxychloride and pentaerythritol and add them to a reaction vessel. Heat to 100 °C and stir. Perform filtration, washing, and vacuum distillation to obtain spiro pentaerythritol bisphosphate dichloride. Dissolve spiro pentaerythritol bisphosphate dichloride and triethylamine in acetonitrile, drop into a mixed solution of 3-aminopropyltriethoxysilane and acetonitrile, stir at 40 °C for 10 h, perform filtration and vacuum distillation to obtain spiro pentaerythritol bisphosphate; Disperse carbon nanotubes in a mixed solution of deionized water and ethanol, add spiro pentaerythritol bisphosphate, use an ultrasonic disperser for dispersion treatment, heat to 80 °C, stir for 10 h to obtain a suspension. Perform filtration and washing on the suspension. Place the filtered product in an oven and dry it at 80 °C for 12 h. Grind the dried product to obtain modified carbon nanotubes; Mix 100 parts of nylon 6 sheet, 0.5 part of modified carbon nanotubes, 15 parts of aluminum ethylphosphinate bis(ethylphosphonate), 5 parts of charring agent, 5 parts of epoxy silica, and 5 parts of compatibilizer using a high-speed mixer to obtain a mixture. Feed the mixture into the feeding port of a twin-screw extruder. Set the temperature of the extruder at 210 - 250 °C. After water-cooled strand pelletization, put the produced pellets into an oven and dry them at 120 °C for 10 h to obtain functional masterbatch.

[0037] Performance Test Test 1 Thermal Stability Test: Weigh 5 mg of the samples prepared in Examples 1 - 6 and Comparative Examples 1 - 3, put them into a thermogravimetric analyzer, and heat them from room temperature to 800 °C at a heating rate of 10 °C / min under a nitrogen atmosphere for testing, and record the initial decomposition temperature T 5% ; Test 2 Limiting Oxygen Index Test: Use a tablet press and a cutting machine to prepare samples of the samples prepared in Examples 1 - 6 and Comparative Examples 1 - 3. The standard size of the test specimen is 3.2 mm × 6.5 mm × 7 mm. Conduct the limiting oxygen index test according to the standard GB / T 2406.2—2009 and record the LOI value. Test 3 Vertical Burning Test: Use a tablet press and a cutting machine to prepare samples of the samples prepared in Examples 1 - 6 and Comparative Examples 1 - 3. The standard size of the test specimen is 3 mm × 13 mm × 100 mm. Conduct the test according to the standard GB / T 2408—2008 and record the burning situation. Test 4 Volume Resistivity Test: Test the samples prepared in Examples 1 - 6 and Comparative Examples 1 - 3 according to the standard GB1410 - 2006 and record the volume resistivity.

[0038] Table 1 Test Results of Sample Performance Test

[0039] Table 2 Test Results of Sample Vertical Burning Test

[0040] Working Principle: Aluminum ethylphosphinate bis(ethylphosphonate) produces small crystals in the reaction system, thus improving the dispersibility and stability during the blending of each component of the functional masterbatch and enhancing the dispersion effect of the material. While improving the antistatic property of the functional masterbatch, the modified carbon nanotubes have good compatibility with other components of the functional masterbatch. When the functional masterbatch burns, aluminum ethyl phosphinate, lignin-based charring agent and flame retardant decompose upon heating, dilute the combustible gas, prevent the spread of fire, and form a carbon layer that blocks heat transfer and isolates oxygen, slowing down the combustion process. The flame retardant with a s-triazine ring and Schiff base structure makes the functional masterbatch less likely to produce molten droplets during combustion, improving the flame retardancy and anti-molten droplet property of the functional masterbatch; The molecular chains in the composite compatibilizer can form a network structure with the molecular chains in the functional masterbatch matrix, enhancing the interaction between the components of the functional masterbatch, improving the compatibility and stability of the material. The modified carbon nanotubes form a conductive network within the functional masterbatch, preventing electrostatic sparks from igniting itself or surrounding combustibles.

[0041] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A super-dispersed flame-retardant engineering plastic masterbatch, characterized in that: Comprising a functional masterbatch, the functional masterbatch comprises the following components by weight: 100 parts of nylon 6 sheet, 0.5 - 8 parts of modified carbon nanotubes, 5 - 15 parts of aluminum ethyl phosphinate bis(ethyl phosphonate), 5 - 15 parts of flame retardant, 2 - 5 parts of charring agent, 0.5 - 5 parts of epoxidized silica, 0.5 - 5 parts of compatibilizer, and the preparation method of the aluminum ethyl phosphinate bis(ethyl phosphonate) comprises the following steps: Dissolve aluminum sulfate in deionized water to prepare a metal salt solution, heat the metal salt solution to 50 °C, slowly drop the mixture of diethyl phosphinic acid and ethyl phosphorous acid into the metal salt solution, and stir for 1 h; Cool to room temperature, carry out filtration, washing and drying treatments, and pulverize the dried product to obtain aluminum ethyl phosphinate bis(ethyl phosphonate).

2. The masterbatch of a hyperdispersed flame-retardant engineering plastic according to claim 1, wherein: The preparation method of the charring agent comprises the following steps: Dissolve enzymatically hydrolyzed lignin in N,N-dimethylformamide solution, sequentially add triglycidyl isocyanurate, aminotrimethylene phosphonic acid, and benzoic acid, carry out ethanol elution, drying and pulverization treatments to obtain the charring agent.

3. A super-dispersed flame-retardant engineering plastic masterbatch according to claim 1, characterized in that: The preparation method of the flame retardant comprises the following steps: Mix benzoguanamine and p-methoxybenzaldehyde and add them to toluene, add p-toluenesulfonic acid, stir evenly and heat to 110 °C, and carry out condensation reflux treatment to obtain a reactant; Use a suction filtration device to filter off the liquid part of the reactant to obtain a solid product, wash the solid product with absolute ethanol, and place the washed solid product in an oven at 50 °C for drying treatment to obtain the flame retardant.

4. The super-dispersed flame-retardant engineering plastic masterbatch according to claim 1, characterized in that: The preparation method of the modified carbon nanotubes comprises the following steps: Disperse carbon nanotubes in a mixed solution of deionized water and ethanol, add spirocyclic pentaerythritol bisphosphate, and use an ultrasonic disperser for dispersion treatment, heat to 80 °C, and stir for 10 h to obtain a suspension; Carry out filtration and washing treatments on the suspension, place the filtered product in an oven and dry at 80 °C for 12 h, and grind the dried product to obtain modified carbon nanotubes.

5. The super-dispersed flame-retardant engineering plastic masterbatch according to claim 4, characterized in that: The preparation method of the spirocyclic pentaerythritol bisphosphate comprises the following steps: Mix phosphorus oxychloride and pentaerythritol and add them to a reaction vessel, heat to 100 °C and stir, carry out filtration, washing and vacuum distillation treatments to obtain spirocyclic pentaerythritol bis(phosphoric dichloride); Dissolve spirocyclic pentaerythritol bis(phosphoric dichloride) and triethylamine in acetonitrile, drop into a mixed solution of 3-aminopropyltriethoxysilane and acetonitrile, stir at 40 °C for 10 h, and carry out filtration and vacuum distillation treatments to obtain spirocyclic pentaerythritol bisphosphate.

6. The super-dispersed flame-retardant engineering plastic masterbatch according to claim 1, wherein: The preparation method of the compatibilizer comprises the following steps: Slowly drop epichlorohydrin into hexamethylenediamine solution, react at 70 °C for 2 h, carry out vacuum dehydration and drying treatments to obtain a polar polymer, add the polar polymer and maleic anhydride grafted polypropylene to xylene, react at 120 °C for 8 h, carry out ethanol washing, suction filtration and drying treatments to obtain an intermediate product; Add the intermediate product to xylene, raise the temperature to 100 °C, sequentially add modified graphene oxide and butylammonium bromide, react at 120 °C for 8 h, and carry out suction filtration, drying and grinding treatments to obtain the compatibilizer.

7. The masterbatch of a super-dispersed flame-retardant engineering plastic according to claim 1, wherein: The epoxidized silica is prepared by modifying silica with 3-glycidoxypropyltrimethoxysilane and n-octyltriethoxysilane.

8. The super-dispersed flame-retardant engineering plastic masterbatch according to claim 6, characterized in that: The modified graphene oxide is prepared by modifying graphene oxide with 2, 3-epoxypropyltrimethylammonium chloride.

9. A preparation method of a hyper-dispersed flame-retardant engineering plastic masterbatch, applicable to the hyper-dispersed flame-retardant engineering plastic masterbatch described in any one of claims 1-8, characterized in that: The preparation method comprises the following steps: S1. Using a high-speed mixer to mix nylon 6 sheets, modified carbon nanotubes, aluminum ethyl bis(diethylphosphite), a flame retardant, a charring agent, epoxidized silica, and a compatibilizer to obtain a mixed material; S2. Feeding the mixed material into the feeding port of a twin-screw extruder, setting the temperature of the extruder at 210-250 °C, performing water-cooled strand pelletization, putting the formed pellets into an oven, and drying at 120 °C for 10 h to obtain a functional masterbatch.

10. The preparation method of a super-dispersed flame-retardant engineering plastic masterbatch according to claim 9, characterized in that: The preparation method further comprises the following steps: S11. Placing nylon 6 sheets in an oven and drying at 120 °C for 10 h.

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