Flame-retardant antioxidant color master batch and preparation method thereof

Abstract

The invention provides a flame-retardant antioxidant color master batch and a preparation method thereof, and relates to the technical field of high polymer materials, and the method is realized by the following steps: firstly, dissolving magnesium chloride and aluminum chloride in deionized water, adding a NaOH solution to react to generate layered double hydroxide, mixing with a phosphorus-nitrogen flame retardant, and modifying; secondly, mixing the modified flame retardant with a double-bond monomer with an antioxidant function, and adding a free radical initiator and a catalyst for polymerization reaction to form pre-dispersed master batch; and finally, mixing the pre-dispersed master batch with an inorganic pigment and a dispersing agent, and performing supercritical CO2 mixing and twin-screw extrusion to obtain the flame-retardant antioxidant color master batch. The color master batch has excellent flame retardance and oxidation resistance, can be widely applied to the fields of buildings, automobiles, electronics and the like, and effectively improves the safety and durability of plastic materials.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, in particular to a flame retardant and antioxidant masterbatch and a preparation method thereof. Background Art

[0002] In the production and application of plastic products, masterbatch is an important additive that not only imparts color to plastics but also improves their processing and physical properties. However, with the widespread application of plastic materials in demanding fields such as construction, automobiles, and electronics, the performance of traditional masterbatches has been unable to meet the demand. In the existing technology, ordinary masterbatches are prone to oxidative degradation in harsh environments such as high temperature, high humidity, or ultraviolet light, resulting in reduced material performance and even safety hazards such as fire. In addition, the flame retardant properties of traditional masterbatches mainly rely on halogen flame retardants. These flame retardants produce toxic smoke and corrosive gases during combustion, which are harmful to the environment and human health. Therefore, the development of a masterbatch with both high-efficiency flame retardant and antioxidant properties, while avoiding the shortcomings of traditional flame retardants, has become an important research direction.

[0003] In recent years, researchers have been dedicated to developing novel flame-retardant and antioxidant systems to improve the overall performance of masterbatches. For example, inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide achieve flame retardancy through their endothermic decomposition and water vapor release. However, these materials often suffer from poor compatibility with polymer matrices and a decrease in mechanical properties due to large addition amounts. Traditional hindered phenolic antioxidants, while effective in resisting oxidation, are prone to volatilization or decomposition at high temperatures, making them difficult to meet long-term use requirements. Therefore, there is an urgent need in the art for a masterbatch that effectively combines flame retardancy and antioxidant functions while overcoming the poor compatibility, performance degradation, and environmental hazards of traditional materials. Summary of the Invention

[0004] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for preparing a flame retardant and antioxidant masterbatch, comprising the following steps:

[0005] S1: dissolving magnesium chloride and aluminum chloride in deionized water, stirring uniformly to obtain a mixed salt solution, adding NaOH solution under stirring conditions, controlling the pH to 9-10, and stirring to react for 2-4 hours. After the reaction is completed, filtering the reaction solution, washing, and drying to obtain a layered double hydroxide, mixing the layered double hydroxide with a phosphorus-nitrogen flame retardant, placing the mixture in a high-speed mixer, spraying the mixture with an ethanol solution of a silane coupling agent, stirring at a high speed of 1200 rpm for 30-40 minutes, and drying the mixture in a vacuum oven at 80°C for 3-4 hours to obtain a modified flame retardant;

[0006] S2: Mix the antioxidant functional double bond monomer with the modified flame retardant prepared in S1, add tetrahydrofuran solvent, add a free radical initiator, a reducing agent, and a metal ion catalyst, add ammonia water to adjust the pH to 8-9, raise the temperature to 60°C-80°C, react for 6-9 hours, and after the reaction is completed, cool to 40°C, immediately add a hindered phenol free radical scavenger to quench residual free radicals, add a free radical scavenging antioxidant, place in a planetary ball mill, rotate at 500 rpm-700 rpm, and grind for 2 hours to form a pre-dispersed masterbatch;

[0007] S3: The pre-dispersed masterbatch, inorganic pigment and dispersant prepared in S2 are put into a supercritical mixing kettle, and supercritical CO2 is injected. The pressure is 10 MPa and the temperature is 50°C. The mixture is sheared and mixed at a high speed of 2000rpm to 3000rpm for 20 minutes to uniformly disperse the components to obtain a mixture. The mixture is fed into a twin-screw extruder with four temperature zones: zone 1 160°C, zone 2 180°C, zone 3 170°C, zone 4 165°C, the screw speed is 400rpm, the die pressure is 15MPa, and the extruded strips are water-cooled and pelletized to obtain a flame-retardant and antioxidant masterbatch.

[0008] Preferably, the silane coupling agent ethanol solution is a mixed solution obtained by compounding silane coupling agent KH-550, silane coupling agent KH-570 and anhydrous ethanol in a ratio of 3:1:16.

[0009] Preferably, all the double-bond monomers with antioxidant functions are acrylic ester antioxidant AO-2246.

[0010] Preferably, the free radical initiator is ammonium persulfate, the reducing agent is ascorbic acid, and the metal ion catalyst is ferrous sulfate.

[0011] Preferably, the hindered phenol free radical scavenger is 2,6-di-tert-butyl-4-methylphenol.

[0012] Preferably, the free radical trapping antioxidant is thiodipropionate.

[0013] Preferably, the inorganic pigment is any one of titanium dioxide, red iron oxide, black iron oxide, carbon black and chromium yellow.

[0014] Preferably, the dispersant is any one or more of polyethylene wax, oleamide, ethylene bisstearamide and zinc stearate.

[0015] Preferably, the mass proportions of the magnesium chloride, aluminum chloride and deionized water are 15 to 25 parts of magnesium chloride, 10 to 18 parts of aluminum chloride and 100 to 180 parts of deionized water; the mass proportions of the layered double hydroxide, phosphorus nitrogen flame retardant and silane coupling agent ethanol solution are 24 to 40 parts of layered double hydroxide, 10 to 15 parts of phosphorus nitrogen flame retardant and 100 to 150 parts of silane coupling agent ethanol solution; the antioxidant functional double bond monomer, modified flame retardant, tetrahydrofuran solvent, free radical initiator, reducing agent, metal ion catalyst, hindered phenol free radical The mass proportions of the scavenger and the free radical scavenging antioxidant are 70-100 parts of the antioxidant functional double bond monomer, 30-50 parts of the modified flame retardant, 200-250 parts of the tetrahydrofuran solvent, 2-5 parts of the free radical initiator, 1-3 parts of the reducing agent, 0.5-1 part of the metal ion catalyst, 2-5 parts of the hindered phenol free radical scavenger, and 1-3 parts of the free radical scavenging antioxidant; the mass proportions of the pre-dispersed masterbatch, the inorganic pigment, and the dispersant are 100-150 parts of the pre-dispersed masterbatch, 15-30 parts of the inorganic pigment, and 5-10 parts of the dispersant.

[0016] The present invention provides a flame retardant and antioxidant masterbatch and a preparation method thereof. It has the following beneficial effects:

[0017] 1. Through the synergistic effect of the layered double hydroxide and phosphorus-nitrogen flame retardant, as well as the modification of the silane coupling agent, the masterbatch forms a protective film during combustion, isolating oxygen, releasing non-combustible gas, and diluting the concentration of combustible gases, thereby effectively preventing combustion. In the UL-94 vertical combustion test, Examples 1-6 all achieved a flame retardancy rating of V-0, with a limiting oxygen index (LOI) above 37%. Thermogravimetric analysis (TGA) showed a 5% mass loss temperature (T5%) above 310°C, demonstrating excellent thermal stability and flame retardancy at high temperatures.

[0018] 2. The double-bond antioxidant undergoes polymerization under the action of the free radical initiator, forming a cross-linked network and simultaneously trapping free radicals, inhibiting oxidation reactions. The synergistic effect of the hindered phenolic free radical scavenger and the free radical-trapping antioxidant further enhances the antioxidant effect. In antioxidant performance testing, Examples 1-6 exhibited an OIT of over 26 minutes and a tensile strength retention rate of over 91% after thermal oxidative aging, demonstrating their ability to effectively resist oxidative degradation and maintain the material's physical properties over long-term use. DETAILED DESCRIPTION

[0019] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0020] Example 1:

[0021] A method for preparing a flame retardant and antioxidant masterbatch comprises the following steps:

[0022] S1: Take 21 parts of magnesium chloride and 12 parts of aluminum chloride and dissolve them in 130 parts of deionized water. Dissolve them fully at a stirring speed of 300 rpm to form a uniform mixed salt solution. Then, under continuous stirring and maintaining the stirring speed at 300 rpm, slowly add NaOH solution to adjust the pH to 9.0 and maintain the pH value for 3 hours. After the reaction is completed, the reaction solution is filtered by vacuum filtration, and the solid product is repeatedly washed with deionized water until the filtrate is neutral. Then, it is dried in a vacuum drying oven at 80°C for 3.5 hours to obtain 30 parts of layered double hydroxide. 30 parts of layered double hydroxide are mixed with 13 parts of phosphorus nitrogen flame retardant, placed in a high-speed mixer and stirred at a high speed of 1200 rpm. At the same time, 125 parts of silane coupling agent ethanol solution are sprayed and stirred for 35 minutes to ensure that the silane coupling agent is fully coated on the surface of the flame retardant. Finally, it is dried in a vacuum oven at 80°C for 3.5 hours to obtain a modified flame retardant.

[0023] S2: Add 85 parts of acrylic antioxidant AO-2246 and 42 parts of modified flame retardant to 220 parts of tetrahydrofuran solvent and mix them evenly at a stirring speed of 400 rpm. Then add 2 parts of ammonium persulfate as a free radical initiator, 1 part of ascorbic acid as a reducing agent, and 0.5 parts of ferrous sulfate as a metal ion catalyst. Use ammonia water to adjust the pH to 8.5, raise the temperature to 70°C, and react under these conditions for 7 hours. After the reaction is completed, the reaction system is cooled to 40°C, and 2 parts of 2,6-di-tert-butyl-4-methylphenol are immediately added as hindered phenol free radical scavengers to quench residual free radicals. Then, 1 part of thiodipropionate is added as a free radical scavenging antioxidant. Place in a planetary ball mill and grind at 600 rpm for 2 hours to form a pre-dispersed masterbatch.

[0024] S3: 135 parts of pre-dispersed masterbatch, 25 parts of titanium dioxide, and 8 parts of polyethylene wax were placed in a supercritical mixing kettle. Supercritical CO2 was injected, and the pressure was maintained at 10 MPa and the temperature at 50°C. High-speed shear mixing was performed at 2500 rpm for 20 minutes to uniformly disperse the components to obtain a mixture. The mixture was fed into a twin-screw extruder with four temperature zones: zone 1 160°C, zone 2 180°C, zone 3 170°C, and zone 4 165°C. The screw speed was 400 rpm, and the die pressure was 15 MPa. The extruded strips were water-cooled and pelletized to obtain a flame-retardant, antioxidant masterbatch.

[0025] Example 2:

[0026] A method for preparing a flame retardant and antioxidant masterbatch comprises the following steps:

[0027] S1: 25 parts magnesium chloride and 18 parts aluminum chloride were dissolved in 180 parts water and uniformly dissolved at a stirring speed of 350 rpm to form a mixed salt solution. NaOH solution was added at a stirring speed of 350 rpm to control the pH to 9.5 and the reaction was stirred for 2.5 hours. After the reaction was completed, the reaction solution was separated into solid and liquid by centrifugation. The solid product was then washed with deionized water until neutral and dried in a vacuum drying oven at 80°C for 4 hours to produce 40 parts of layered double hydroxide. This was mixed with 10 parts of phosphorus-nitrogen flame retardant and placed in a high-speed mixer. Stir at a high speed of 1300 rpm and sprayed with 180 parts of silane coupling agent ethanol solution. Stir for 30 minutes to evenly coat the flame retardant with the silane coupling agent. The mixture was then dried in a vacuum oven at 80°C for 4 hours to obtain a modified flame retardant.

[0028] S2: 100 parts of acrylate antioxidant AO-2246 and 50 parts of modified flame retardant were added to 250 parts of tetrahydrofuran solvent and mixed at 450 rpm. Three parts of ammonium persulfate were added as a free radical initiator, two parts of ascorbic acid as a reducing agent, and 0.8 parts of ferrous sulfate as a metal ion catalyst. The pH was adjusted to 8.8 with aqueous ammonia. The temperature was raised to 65°C and the reaction was allowed to proceed for 8 hours. After the reaction, the mixture was cooled to 40°C, and three parts of 2,6-di-tert-butyl-4-methylphenol and two parts of thiodipropionate were added. The mixture was then milled in a planetary ball mill at 550 rpm for 2 hours to form a pre-dispersed masterbatch.

[0029] S3: 148 parts of pre-dispersed masterbatch, 20 parts of red iron oxide, and a dispersant mixture of 8 parts of oleamide and zinc stearate in a 1:1 ratio were placed in a supercritical mixing kettle. Supercritical CO2 was injected at a pressure of 10 MPa and a temperature of 50°C. High-speed shear mixing was performed at 2800 rpm for 20 minutes to fully disperse the components and obtain a mixture. The mixture was fed into a twin-screw extruder with the extruder temperatures set at 160°C for zone 1, 180°C for zone 2, 170°C for zone 3, and 165°C for zone 4. The screw speed was 400 rpm, and the die pressure was 15 MPa. The extruded strips were water-cooled and pelletized to produce flame-retardant antioxidant masterbatch.

[0030] Example 3:

[0031] A method for preparing a flame retardant and antioxidant masterbatch comprises the following steps:

[0032] S1: 15 parts of magnesium chloride and 10 parts of aluminum chloride were added to 100 parts of deionized water and dissolved uniformly at a stirring speed of 400 rpm to form a mixed salt solution. NaOH solution was added at a stirring speed of 400 rpm, the pH was controlled to 9.0, and the reaction was stirred for 3 hours. After the reaction was completed, 24 parts of layered double hydroxide were obtained by filtering, washing, and vacuum drying at 80°C for 3 hours. This was mixed with 18 parts of phosphorus-nitrogen flame retardant, placed in a high-speed mixer, stirred at a high speed of 1250 rpm, and sprayed with 200 parts of silane coupling agent ethanol solution. The mixture was stirred for 40 minutes to evenly coat the flame retardant with the silane coupling agent. The mixture was then dried in a vacuum oven at 80°C for 3 hours to obtain a modified flame retardant.

[0033] S2: 72 parts of acrylic antioxidant AO-2246 and 41 parts of modified flame retardant were added to 235 parts of tetrahydrofuran solvent and mixed evenly at a stirring speed of 500 rpm. 4 parts of ammonium persulfate as a free radical initiator, 2.5 parts of ascorbic acid as a reducing agent, and 0.9 parts of ferrous sulfate as a metal ion catalyst were added. The pH was adjusted to 9.0 with ammonia water, and the temperature was raised to 75°C and the reaction was carried out for 6.5 hours. After the reaction was completed, the mixture was cooled to 40°C, 4 parts of 2,6-di-tert-butyl-4-methylphenol and 2.5 parts of thiodipropionate were added, and the mixture was placed in a planetary ball mill and ground at a speed of 650 rpm for 2 hours to form a pre-dispersed masterbatch.

[0034] S3: 111 parts of pre-dispersed masterbatch, 25 parts of carbon black, and 9 parts of ethylene bisstearamide were placed in a supercritical mixing kettle. Supercritical CO2 was injected at a pressure of 10 MPa and a temperature of 50°C. High-speed shear mixing was performed at 3000 rpm for 20 minutes to uniformly disperse the components to obtain a mixture. The mixture was fed into a twin-screw extruder with four temperature zones: zone 1 162°C, zone 2 182°C, zone 3 172°C, and zone 4 168°C. The screw speed was 400 rpm, and the die pressure was 15 MPa. The extruded strips were water-cooled and pelletized to obtain a flame-retardant, antioxidant masterbatch.

[0035] Example 4:

[0036] A method for preparing a flame retardant and antioxidant masterbatch comprises the following steps:

[0037] S1: 20 parts of magnesium chloride and 15 parts of aluminum chloride were dissolved in 140 parts of deionized water, and a mixed salt solution was formed at a stirring speed of 450 rpm. NaOH solution was added at a stirring speed of 450 rpm, the pH was controlled to 9.5, and the reaction was stirred for 2.5 hours. After the reaction was completed, 33 parts of layered double hydroxide were obtained by filtering, washing, and vacuum drying at 80°C for 4 hours. This was mixed with 14 parts of phosphorus-nitrogen flame retardant, placed in a high-speed mixer, stirred at a high speed of 1200 rpm, and sprayed with 210 parts of silane coupling agent ethanol solution. The mixture was stirred for 38 minutes to evenly coat the flame retardant with the silane coupling agent. The mixture was then dried in a vacuum oven at 80°C for 4 hours to obtain a modified flame retardant.

[0038] S2: 90 parts of acrylic antioxidant AO-2246 and 45 parts of modified flame retardant were added to 250 parts of tetrahydrofuran solvent and mixed evenly at a stirring speed of 550 rpm. 5 parts of ammonium persulfate as a free radical initiator, 3 parts of ascorbic acid as a reducing agent, and 1 part of ferrous sulfate as a metal ion catalyst were added. The pH was adjusted to 9.0 with ammonia water, and the temperature was raised to 80°C and the reaction was allowed to proceed for 9 hours. After the reaction was completed, the mixture was cooled to 40°C, 5 parts of 2,6-di-tert-butyl-4-methylphenol and 3 parts of thiodipropionate were added, and the mixture was placed in a planetary ball mill and ground at a speed of 700 rpm for 2 hours to form a pre-dispersed masterbatch.

[0039] S3: 130 parts of pre-dispersed masterbatch, 30 parts of chrome yellow, and a dispersant mixture of 10 parts of polyethylene wax and zinc stearate in a ratio of 2:1 were placed in a supercritical mixing kettle. Supercritical CO2 was injected at a pressure of 10 MPa and a temperature of 50°C. High-speed shear mixing was performed at 2000 rpm for 20 minutes to uniformly disperse the components to obtain a mixture. The mixture was fed into a twin-screw extruder with four temperature zones: zone 1 160°C, zone 2 180°C, zone 3 170°C, and zone 4 165°C. The screw speed was 400 rpm, and the die pressure was increased to 16 MPa. The extruded strips were water-cooled and pelletized to obtain a flame-retardant, antioxidant masterbatch.

[0040] Example 5:

[0041] A method for preparing a flame retardant and antioxidant masterbatch comprises the following steps:

[0042] S1: 25 parts of magnesium chloride and 16 parts of aluminum chloride were added to 170 parts of deionized water and dissolved uniformly at a stirring speed of 320 rpm to form a mixed salt solution. NaOH solution was added under a stirring speed of 320 rpm to control the pH to 9.2. The mixture was stirred for 3.2 hours. After the reaction, 39 parts of layered double hydroxide were obtained by filtering, washing, and drying (80°C vacuum drying for 3.2 hours). It was mixed with 13 parts of phosphorus nitrogen flame retardant, placed in a high-speed mixer, stirred at a high speed of 1250 rpm, sprayed with 150 parts of silane coupling agent ethanol solution, stirred for 33 minutes, so that the silane coupling agent was evenly coated on the surface of the flame retardant, and then dried in a vacuum oven at 80°C for 3.2 hours to obtain a modified flame retardant.

[0043] S2: 95 parts of acrylic antioxidant AO-2246 and 50 parts of modified flame retardant are added to 110 parts of tetrahydrofuran solvent, mixed evenly at a stirring speed of 420 rpm, 2.5 parts of ammonium persulfate as a free radical initiator, 1.5 parts of ascorbic acid as a reducing agent, and 0.6 parts of ferrous sulfate as a metal ion catalyst are added, the pH is adjusted to 8.6 with ammonia water, the temperature is raised to 68 ° C, and the reaction is carried out for 7.5 hours. After the reaction is completed, it is cooled to 40 ° C, 2.5 parts of 2,6-di-tert-butyl-4-methylphenol and 1.5 parts of thiodipropionate are added, and the mixture is placed in a planetary ball mill and ground at a speed of 620 rpm for 2 hours to form a pre-dispersed masterbatch.

[0044] S3: Take 148 parts of pre-dispersed masterbatch, 18 parts of black iron oxide, and 6 parts of oleamide, put them into a supercritical mixing kettle, inject supercritical CO2, pressure 10 MPa, temperature 50°C, and high-speed shear mixing at 2700 rpm for 20 minutes to uniformly disperse the components to obtain a mixture. The mixture is fed into a twin-screw extruder with four temperature zones: zone 1 160°C, zone 2 178°C, zone 3 170°C, zone 4 165°C, screw speed 400 rpm, die head pressure 15 MPa, and the extruded strips are water-cooled and pelletized to obtain a flame retardant and antioxidant masterbatch.

[0045] Example 6:

[0046] A method for preparing a flame retardant and antioxidant masterbatch comprises the following steps:

[0047] S1: 15 parts of magnesium chloride and 11 parts of aluminum chloride were dissolved in 105 parts of deionized water at a stirring speed of 480 rpm to form a mixed salt solution. NaOH solution was added at a stirring speed of 480 rpm to control the pH to 9.3. The mixture was stirred for 3.5 hours. After the reaction, 25 parts of layered double hydroxide were obtained by filtering, washing, and vacuum drying at 80°C for 3.8 hours. The layered double hydroxide was mixed with 10 parts of phosphorus-nitrogen flame retardant, placed in a high-speed mixer, stirred at a high speed of 1280 rpm, and sprayed with 100 parts of silane coupling agent ethanol solution. The mixture was stirred for 37 minutes to evenly coat the flame retardant with the silane coupling agent. The mixture was then dried in a vacuum oven at 80°C for 3.8 hours to obtain a modified flame retardant.

[0048] S2: 100 parts of acrylic antioxidant AO-2246 and 33 parts of modified flame retardant were added to 200 parts of tetrahydrofuran solvent and mixed at a stirring speed of 520 rpm. 4.5 parts of ammonium persulfate as a free radical initiator, 2.8 parts of ascorbic acid as a reducing agent, and 0.95 parts of ferrous sulfate as a metal ion catalyst were added. The pH was adjusted to 8.9 with aqueous ammonia, and the temperature was raised to 77°C and the reaction was allowed to proceed for 8.5 hours. After the reaction was completed, the mixture was cooled to 40°C, 4.5 parts of 2,6-di-tert-butyl-4-methylphenol and 2.8 parts of thiodipropionate were added, and the mixture was placed in a planetary ball mill and milled at 680 rpm for 2 hours to form a pre-dispersed masterbatch.

[0049] S3: 130 parts of pre-dispersed masterbatch, 28 parts of an inorganic pigment (a mixture of titanium dioxide and carbon black in a ratio of 3:1), and 9.5 parts of a dispersant (a mixture of polyethylene wax and ethylene diester in a ratio of 2:1) were placed in a supercritical mixing kettle. Supercritical CO2 was injected at a pressure of 10 MPa and a temperature of 50°C. High-speed shear mixing was performed at 2900 rpm for 20 minutes to uniformly disperse the components to obtain a mixture. The mixture was fed into a twin-screw extruder with four temperature zones: zone 1 160°C, zone 2 180°C, zone 3 170°C, and zone 4 166°C. The screw speed was 400 rpm, and the die pressure was 15 MPa. The extruded strips were water-cooled and pelletized to obtain a flame-retardant, antioxidant masterbatch.

[0050] It should be noted that magnesium chloride and aluminum chloride react with sodium hydroxide to form layered double hydroxide, in which the metal ion layer and the hydroxide layer form a layered structure. This structure can release water molecules when heated and has flame retardant mechanisms such as expansion, heat insulation, and oxygen isolation.

[0051] It should be noted that phosphorus-nitrogen flame retardant is an organic flame retardant. It forms a protective film during the combustion process by releasing phosphorus and nitrogen compounds to isolate oxygen. At the same time, it releases non-combustible gas to dilute the concentration of combustible gas. After mixing with layered double hydroxide, it forms a synergistic flame retardant system with the layered double hydroxide through the action of silane coupling agent, thereby enhancing the flame retardant effect.

[0052] It should be noted that antioxidants containing double bonds can participate in free radical polymerization reactions. Under the action of free radical initiators, the double bonds undergo polymerization reactions to form a cross-linked network. At the same time, the free radical capturing ability of the antioxidant can inhibit the oxidation reaction.

[0053] It should be noted that the hindered phenol free radical scavenger 2,6-di-tert-butyl-4-methylphenol captures residual free radicals to prevent the oxidation reaction from continuing. After the reaction is completed, it quenches the residual free radicals, terminates the oxidation reaction, and protects the stability of the cross-linked network.

[0054] It should be noted that the free radical-trapping antioxidant thiodipropionate further captures free radicals, provides long-term antioxidant protection, plays an antioxidant protection role in the cross-linked network, and prevents the degradation of the cross-linked structure.

[0055] Comparative Example 1:

[0056] A method for preparing a flame retardant and antioxidant masterbatch comprises the following steps:

[0057] S1: Take 21 parts of magnesium chloride and 12 parts of aluminum chloride and dissolve them in 130 parts of deionized water. Dissolve them fully at a stirring speed of 300 rpm to form a uniform mixed salt solution. Then, slowly add NaOH solution under continuous stirring and maintaining the stirring speed at 300 rpm to adjust the pH to 9.0. Maintain the pH value for 3 hours. After the reaction is completed, the reaction solution is filtered by vacuum filtration, and the solid product is repeatedly washed with deionized water until the filtrate is neutral. Then, it is dried in a vacuum drying oven at 80°C for 3.5 hours to obtain 30 parts of layered double hydroxide. It is mixed with 13 parts of phosphorus nitrogen flame retardant, placed in a high-speed mixer, stirred at a high speed of 1200 rpm, without spraying the silane coupling agent ethanol solution, and continued to stir for 35 minutes. Finally, it is dried in a vacuum oven at 80°C for 3.5 hours to obtain an unmodified flame retardant.

[0058] S2: Add 85 parts of acrylate antioxidant AO-2246 and 41 parts of unmodified flame retardant to 220 parts of tetrahydrofuran solvent and mix them evenly at a stirring speed of 400 rpm. Then add 2 parts of ammonium persulfate as a free radical initiator, 1 part of ascorbic acid as a reducing agent, and 0.5 parts of ferrous sulfate as a metal ion catalyst. Use ammonia water to adjust the pH to 8.5, raise the temperature to 70°C, and react under these conditions for 7 hours. After the reaction is completed, the reaction system is cooled to 40°C, and 2 parts of 2,6-di-tert-butyl-4-methylphenol are immediately added as hindered phenol free radical scavengers to quench residual free radicals. Then, 1 part of thiodipropionate is added as a free radical scavenging antioxidant. Place in a planetary ball mill and grind at a speed of 600 rpm for 2 hours to form a pre-dispersed masterbatch.

[0059] S3: 132 parts of pre-dispersed masterbatch, 15 parts of titanium dioxide, and 5 parts of polyethylene wax were placed in a supercritical mixing kettle. Supercritical CO2 was injected, and the pressure was maintained at 10 MPa and the temperature was 50°C. High-speed shear mixing was performed at 2500 rpm for 20 minutes to uniformly disperse the components to obtain a mixture. The mixture was fed into a twin-screw extruder with four temperature zones: zone 1 160°C, zone 2 180°C, zone 3 170°C, and zone 4 165°C. The screw speed was 400 rpm, and the die pressure was 15 MPa. The extruded strips were water-cooled and pelletized to obtain a flame-retardant, antioxidant masterbatch.

[0060] Comparative Example 2:

[0061] A method for preparing a flame retardant and antioxidant masterbatch comprises the following steps:

[0062] S1: Take 21 parts of magnesium chloride and 12 parts of aluminum chloride and dissolve them in 130 parts of deionized water. Dissolve them fully at a stirring speed of 300 rpm to form a uniform mixed salt solution. Then, under continuous stirring and maintaining the stirring speed at 300 rpm, slowly add NaOH solution to adjust the pH to 9.0 and maintain the pH value for 3 hours. After the reaction is completed, the reaction solution is filtered by vacuum filtration, and the solid product is repeatedly washed with deionized water until the filtrate is neutral. Then, it is dried in a vacuum drying oven at 80°C for 3.5 hours to obtain 30 parts of layered double hydroxide. It is mixed with 13 parts of phosphorus nitrogen flame retardant, placed in a high-speed mixer, stirred at a high speed of 1200 rpm, and sprayed with 150 parts of silane coupling agent ethanol solution. Stirring is continued for 35 minutes to ensure that the silane coupling agent is fully coated on the surface of the flame retardant. Finally, it is dried in a vacuum oven at 80°C for 3.5 hours to obtain a modified flame retardant.

[0063] S2: Add 85 parts of acrylic antioxidant AO-2246 and 42 parts of modified flame retardant to 100 parts of tetrahydrofuran solvent and mix them evenly at a stirring speed of 400 rpm. Then add 2 parts of ammonium persulfate as a free radical initiator, 1 part of ascorbic acid as a reducing agent, and 0.5 parts of ferrous sulfate as a metal ion catalyst. Use ammonia water to adjust the pH to 8.5, raise the temperature to 70°C, and react under these conditions for 7 hours. After the reaction is completed, the reaction system is cooled to 40°C. 2,6-di-tert-butyl-4-methylphenol is not added as a hindered phenol free radical scavenger to quench residual free radicals. Then, 1 part of thiodipropionate is added as a free radical scavenging antioxidant. Place in a planetary ball mill and grind at a speed of 600 rpm for 2 hours to form a pre-dispersed masterbatch.

[0064] S3: 136 parts of pre-dispersed masterbatch, 15 parts of titanium dioxide, and 5 parts of polyethylene wax were placed in a supercritical mixing kettle. Supercritical CO2 was injected, and the pressure was maintained at 10 MPa and the temperature was 50°C. High-speed shear mixing was performed at 2500 rpm for 20 minutes to uniformly disperse the components to obtain a mixture. The mixture was fed into a twin-screw extruder with four temperature zones: zone 1 160°C, zone 2 180°C, zone 3 170°C, and zone 4 165°C. The screw speed was 400 rpm, and the die pressure was 15 MPa. The extruded strips were water-cooled and pelletized to obtain a flame-retardant, antioxidant masterbatch.

[0065] Comparative Example 3:

[0066] A method for preparing a flame retardant and antioxidant masterbatch comprises the following steps:

[0067] S1: Take 21 parts of magnesium chloride and 12 parts of aluminum chloride and dissolve them in 130 parts of deionized water. Dissolve them fully at a stirring speed of 300 rpm to form a uniform mixed salt solution. Then, under continuous stirring and maintaining the stirring speed at 300 rpm, slowly add NaOH solution to adjust the pH to 9.0 and maintain the pH value for 3 hours. After the reaction is completed, the reaction solution is filtered by vacuum filtration, and the solid product is repeatedly washed with deionized water until the filtrate is neutral. Then, it is dried in a vacuum drying oven at 80°C for 3.5 hours to obtain 30 parts of layered double hydroxide. It is mixed with 13 parts of phosphorus nitrogen flame retardant, placed in a high-speed mixer, stirred at a high speed of 1200 rpm, and sprayed with 150 parts of silane coupling agent ethanol solution. Stirring is continued for 35 minutes to ensure that the silane coupling agent is fully coated on the surface of the flame retardant. Finally, it is dried in a vacuum oven at 80°C for 3.5 hours to obtain a modified flame retardant.

[0068] S2: Add 85 parts of acrylic antioxidant AO-2246 and 42 parts of modified flame retardant to 220 parts of tetrahydrofuran solvent and mix them evenly at a stirring speed of 400 rpm. Then add 2 parts of ammonium persulfate as a free radical initiator, 1 part of ascorbic acid as a reducing agent, and 0.5 parts of ferrous sulfate as a metal ion catalyst. Use ammonia water to adjust the pH to 8.5, raise the temperature to 70°C, and react under these conditions for 7 hours. After the reaction is completed, the reaction system is cooled to 40°C, and 2 parts of 2,6-di-tert-butyl-4-methylphenol are immediately added as a hindered phenol free radical scavenger to quench residual free radicals. No thiodipropionate is added as a free radical scavenging antioxidant. Place in a planetary ball mill and grind at a speed of 600 rpm for 2 hours to form a pre-dispersed masterbatch.

[0069] S3: 135 parts of pre-dispersed masterbatch, 25 parts of titanium dioxide, and 8 parts of polyethylene wax were placed in a supercritical mixing kettle. Supercritical CO2 was injected, and the pressure was maintained at 10 MPa and the temperature at 50°C. High-speed shear mixing was performed at 2500 rpm for 20 minutes to uniformly disperse the components to obtain a mixture. The mixture was fed into a twin-screw extruder with four temperature zones: zone 1 160°C, zone 2 180°C, zone 3 170°C, and zone 4 165°C. The screw speed was 400 rpm, and the die pressure was 15 MPa. The extruded strips were water-cooled and pelletized to obtain a flame-retardant, antioxidant masterbatch.

[0070] Flame retardant performance test:

[0071] UL-94 vertical burning test: According to ASTM D3801 standard, the flame retardant masterbatch prepared in Examples 1-6 and Comparative Examples 1-3 was subjected to UL-94 vertical burning test to test the burning grade of the test specimens (V-0 / V-1 / V-2 / NR).

[0072] Limiting Oxygen Index (LOI): According to ASTM D2863, the flame retardant masterbatches prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were tested to determine the minimum oxygen concentration (%) at which the material can sustain combustion in a mixture of oxygen and nitrogen.

[0073] Thermogravimetric analysis (TGA): The flame retardant masterbatches prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were tested by heating to 800° C. at 10° C. / min under a nitrogen atmosphere and recording the 5% mass loss temperature (T5%, ° C.).

[0074] Antioxidant performance test:

[0075] Oxidation induction time (OIT): The flame retardant and antioxidant masterbatches prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were tested by using a differential scanning calorimeter (DSC) at 200° C. to measure the induction time (min) of the oxidation reaction of the samples.

[0076] Tensile strength retention after thermal oxidative aging: The flame retardant antioxidant masterbatches prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were tested. The samples were placed in an oven at 120°C for 168 hours, and the change rate (%) of the tensile strength before and after aging was tested.

[0077] Table 1: Flame retardant properties

[0078]

[0079]

[0080] Table 2: Antioxidant properties

[0081] Example 1 OIT(min) Strength retention after thermal oxidative aging (%) Example 2 27.5 94.0 Example 3 26.2 93.5 Example 4 26.8 91.8 Example 5 26.0 92.5 Example 6 27.2 91.9 Comparative Example 1 26.1 87.6 Comparative Example 2 25.7 88.3 Comparative Example 3 25.2 86.9

[0082] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a flame retardant and antioxidant masterbatch, characterized in that: The following steps are involved: S1: dissolving magnesium chloride and aluminum chloride in deionized water, stirring evenly to obtain a mixed salt solution, adding NaOH solution under stirring conditions, controlling the pH to 9-10, stirring and reacting for 2-4 hours, filtering the reaction solution after the reaction, washing, and drying to obtain a layered double hydroxide, mixing the layered double hydroxide with a phosphorus nitrogen flame retardant, placing in a high-speed mixer, spraying with a silane coupling agent ethanol solution, stirring at a high speed of 1200 rpm for 30-40 minutes, and drying in a vacuum oven at 80°C for 3-4 hours to obtain a modified flame retardant; S2: Mix the antioxidant functional double bond monomer with the modified flame retardant prepared in S1, add tetrahydrofuran solvent, add free radical initiator, reducing agent, metal ion catalyst, add ammonia water to adjust the pH to 8-9, heat to 60°C-80°C, react for 6-9h, after the reaction is completed, cool to 40°C, immediately add hindered phenol free radical scavenger to quench residual free radicals, add free radical scavenging antioxidant, place in a planetary ball mill, rotate at 500rpm-700rpm, grind for 2 hours in the ball mill to form a pre-dispersed masterbatch; S3: The pre-dispersed masterbatch, inorganic pigment and dispersant prepared in S2 are put into a supercritical mixing kettle, and supercritical CO2 is injected. The pressure is 10MPa and the temperature is 50°C. The mixture is sheared and mixed at a high speed of 2000rpm-3000rpm for 20 minutes to uniformly disperse the components to obtain a mixed material. The mixed material is fed into a twin-screw extruder, and four temperature zones are set: zone 1 160°C, zone 2 180°C, zone 3 170°C, zone 4 165°C, the screw speed is 400rpm, the die pressure is 15MPa, and the extruded strips are water-cooled and pelletized to obtain a flame-retardant and antioxidant masterbatch.

2. The method for preparing a flame retardant and antioxidant masterbatch according to claim 1, characterized in that: The silane coupling agent ethanol solution is a mixed solution obtained by compounding silane coupling agent KH-550, silane coupling agent KH-570 and anhydrous ethanol in a ratio of 3:1:

16.

3. The method for preparing a flame retardant and antioxidant masterbatch according to claim 1, characterized in that: All the double bond monomers with antioxidant functions are acrylic antioxidants AO-2246.

4. The method for preparing a flame retardant and antioxidant masterbatch according to claim 1, characterized in that: The free radical initiator is ammonium persulfate, the reducing agent is ascorbic acid, and the metal ion catalyst is ferrous sulfate.

5. The method for preparing a flame retardant and antioxidant masterbatch according to claim 1, characterized in that: The hindered phenol free radical scavenger is 2,6-di-tert-butyl-4-methylphenol.

6. The method for preparing a flame retardant and antioxidant masterbatch according to claim 1, characterized in that: The free radical capture antioxidant is thiodipropionate.

7. The method for preparing a flame retardant and antioxidant masterbatch according to claim 1, characterized in that: The inorganic pigment is any one of titanium dioxide, red iron oxide, black iron oxide, carbon black and complex yellow.

8. The method for preparing a flame retardant and antioxidant masterbatch according to claim 1, characterized in that: The dispersant is any one or more of polyethylene wax, oleic acid amide, ethylene bis stearic acid amide and zinc stearate.

9. The method for preparing a flame retardant and antioxidant masterbatch according to claim 1, characterized in that: The mass proportions of the magnesium chloride, aluminum chloride and deionized water are 15-25 parts of magnesium chloride, 10-18 parts of aluminum chloride and 100-180 parts of deionized water; the mass proportions of the layered double hydroxide, phosphorus nitrogen flame retardant and silane coupling agent ethanol solution are 24-40 parts of layered double hydroxide, 10-15 parts of phosphorus nitrogen flame retardant and 100-150 parts of silane coupling agent ethanol solution; the antioxidant functional double bond monomer, modified flame retardant, tetrahydrofuran solvent, free radical initiator, reducing agent, metal ion catalyst, hindered phenol free radical capture The weight proportions of the pre-dispersed masterbatch, inorganic pigment and dispersant are 70-150 parts of pre-dispersed masterbatch, 15-30 parts of inorganic pigment and 5-10 parts of dispersant.

10. A flame retardant and antioxidant masterbatch, characterized in that: The flame retardant and antioxidant masterbatch is obtained by the preparation method of any one of claims 1 to 9.

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