Melamine cyanurate flame retardant as well as preparation method and application thereof

Abstract

The invention provides a melamine cyanurate flame retardant as well as a preparation method and application thereof, and relates to the technical field of flame retardants. The flame retardant provided by the invention is prepared from the following components in parts by mass: 60 to 80 parts of modified melamine cyanurate, 10 to 15 parts of filler and 5 to 10 parts of compatilizer, the preparation method of the modified melamine cyanurate comprises the following steps: heating melamine and cyanuric acid in cardanol to 70-90 DEG C, separating, drying and crushing to obtain the modified melamine cyanurate. According to the invention, melamine and cyanuric acid are subjected to a heating reaction in cardanol, so that cardanol molecules can be promoted to be added on melamine cyanurate, and the compatibility of modified melamine cyanurate in a high-molecular polymer is improved; further, the flame retardant property of the flame retardant is improved, and the mechanical property of a high polymer material added with the flame retardant is improved.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardants, and in particular to a melamine cyanurate flame retardant and a preparation method and application thereof. Background Art

[0002] Melamine cyanurate (MCA) is a large planar molecular complex with a layered structure formed by hydrogen bonding of melamine (MEL) and cyanuric acid (CA). MCA has high thermal stability, begins to sublime at 350°C, and begins to decompose at 440-450°C. It is very stable below 300°C, dehydrates to carbon and releases nitrogen at high temperatures, which can dilute the concentration of oxygen and combustible gases around the combustion environment, and does not produce other toxic and harmful gases. It is an excellent nitrogen-based flame retardant and is widely used and recognized in the fields of polymer materials such as nylon, rubber, phenolic resin, epoxy resin, and polyvinyl chloride.

[0003] In the prior art, the cyanuric acid method is mainly used for preparing MCA, in which equimolar melamine and cyanuric acid are reacted at high temperature until they become viscous, and then dried, separated and crushed to obtain MCA. This method is simple in process and has high product purity. However, due to the high melting point and large cohesive energy of MCA, the compatibility of MCA when blended with other high molecular polymers is poor, which greatly affects the flame retardant properties and applicability of MCA. Therefore, it is urgent to provide a solution to improve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a melamine cyanurate flame retardant and a preparation method and application thereof. By using cardanol to modify the reaction of melamine and cyanuric acid, a modified melamine cyanurate flame retardant is obtained, which can effectively improve the compatibility of the flame retardant in high molecular polymers, and can also improve the flame retardant properties, mechanical properties and anti-aging properties of the polymer material after adding the flame retardant.

[0005] In a first aspect, the present invention provides a melamine cyanurate flame retardant, which comprises 60-80 parts of modified melamine cyanurate, 10-15 parts of filler and 5-10 parts of compatibilizer in parts by mass; the preparation method of the modified melamine cyanurate comprises: mixing melamine and cyanuric acid in a molar ratio of 1:(0.8-1.2) at 100-150°C and ball milling for 5-8h to obtain a mixed powder; adding the mixed powder into cardanol and ball milling and then ultrasonically dispersing to obtain a mixed slurry; keeping the mixed slurry at 70-90°C and stirring for reaction for 3-5h, centrifuging at a speed of 200-300rpm to separate the precipitate, and then drying and crushing to obtain modified melamine cyanurate.

[0006] The flame retardant provided by the present invention can promote the addition of cardanol molecules to melamine urate by heating melamine and cyanuric acid in cardanol, thereby improving the compatibility of modified melamine cyanurate in high molecular polymers, thereby improving the flame retardant properties of the flame retardant and improving the mechanical properties of the high molecular material to which the flame retardant is added.

[0007] Optionally, after the melamine and the cyanuric acid are mixed, they are ball milled at a ball-to-material ratio of (15-25):1.

[0008] Optionally, the mass volume ratio of the mixed powder to the cardanol is 0.08-0.10 g / mL.

[0009] Optionally, the mixed powder is added into the cardanol and stirred and soaked for 30-60 minutes before ball milling.

[0010] Optionally, the mixed powder is added to the cardanol for ultrasonic dispersion and then ball milled.

[0011] Optionally, the mixed powder is added into the cardanol and ball milled at 100-150°C.

[0012] Optionally, the mixed powder is added into the cardanol and ball-milled for 3-5 hours.

[0013] Optionally, the mixed powder is added to cardanol and ball-milled, followed by ultrasonic mixing at a frequency of 10-30 kHz for 10-15 minutes.

[0014] Optionally, the mixed slurry is heated to 70-90° C. at a rate of 1-5° C. / min.

[0015] Optionally, the mixed slurry is kept at 70-90° C. and stirred at a rotation speed of 100-150 rpm for reaction.

[0016] Optionally, after the mixed slurry is kept warm at 70-90° C., an inert gas is introduced into the bottom of the mixed slurry for bubbling and stirring to react.

[0017] Optionally, after centrifugation at 200-300 rpm and standing for 30-40 min, the supernatant is removed and the precipitate is separated.

[0018] Optionally, after centrifugation at a speed of 200-300 rpm, the supernatant is removed, and deionized water is added for centrifugal washing to separate the precipitate.

[0019] Optionally, the separated precipitate is dried in a vacuum environment at 80-100° C., and then ground, crushed and sieved to obtain modified melamine cyanurate.

[0020] Optionally, the separated precipitate is ground and sieved, and then dried in a vacuum environment at 80-100° C. to obtain modified melamine cyanurate.

[0021] Optionally, the filler is aluminum hydroxide.

[0022] Optionally, the compatibilizer is KH-550 coupling agent.

[0023] In a second aspect, the present invention further provides a method for preparing any of the above optional flame retardants, comprising the following steps: grinding and blending modified melamine cyanurate, a filler and a compatibilizer to obtain a flame retardant.

[0024] In a third aspect, the present invention also provides the use of any of the above-mentioned optional flame retardants.

[0025] The method for preparing melamine cyanurate provided by the present invention has at least one of the following beneficial technical effects: 1. The method provided by the present invention is simple to operate and does not require the use of complex mechanical equipment; 2. The melamine cyanurate prepared by the method provided by the present invention has good compatibility in high molecular polymers, and can also improve the flame retardant properties, mechanical properties and anti-aging properties of polymeric materials after adding flame retardants. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with general skills in the field to which the present invention belongs.

[0027] The present invention provides a melamine cyanurate flame retardant, which comprises 60-80 parts of modified melamine cyanurate, 10-15 parts of filler and 5-10 parts of compatibilizer by weight. In fact, the modified melamine cyanurate, as the main flame retardant component, decomposes and absorbs heat during the combustion process and reduces the surface temperature of the material. At the same time, it dehydrates itself into carbon to form non-combustibles that cover the surface of the material, thereby isolating the air, preventing heat transfer and reducing thermal conductivity, which is conducive to the self-extinguishing of the material from the fire. At the same time, the dispersibility and compatibility of the modified melamine cyanurate in the material are improved, which is conducive to improving the flame retardant performance.

[0028] Specifically, the preparation method of modified melamine cyanurate includes: heating melamine and cyanuric acid to 70-90°C in cardanol, separating and drying and crushing to obtain modified melamine cyanurate. In fact, reacting at 70-90°C can provide sufficient activation energy for the reaction between melamine and cyanuric acid, and promote the reaction between melamine and cyanuric acid, while also improving the molecular activity of cardanol, which is beneficial to the modification of melamine cyanurate by cardanol. In addition, after the reaction is completed, a separation step is carried out, which is beneficial to separating the modified melamine cyanurate from the system, removing the incompletely reacted cardanol and the generated water, and is beneficial to improving the purity and quality stability of the modified melamine cyanurate.

[0029] In fact, when melamine reacts with cyanuric acid, the amino group in the melamine molecule and the carboxyl group in the cyanuric acid molecule undergo dehydration condensation to form melamine cyanurate and water. In addition, since the reaction takes place in cardanol, the hydroxyl group in cardanol can form hydrogen bonds with melamine cyanurate, and at the same time, the unsaturated hydrocarbon group in cardanol can form a π-π effect with melamine cyanurate, thereby achieving modification of melamine cyanurate, thereby improving the compatibility and dispersibility of the modified melamine cyanurate in high molecular polymers.

[0030] In some embodiments, the preparation method of modified melamine cyanurate comprises the following steps: S1. Mix melamine and cyanuric acid at 100-150° C. and ball-mill for 5-8 hours to obtain a mixed powder; S2, adding the mixed powder into cardanol, ball-milling and ultrasonically dispersing to obtain a mixed slurry; S3. Keep the mixed slurry at 70-90° C. and stir for 3-5 hours, centrifuge at 200-300 rpm to separate the precipitate, and then dry and crush to obtain modified melamine cyanurate.

[0031] In fact, when performing step S1, mixed ball milling is used to allow melamine and cyanuric acid to be fully mixed under the collision and friction sound of the ball milling balls, thereby ensuring that melamine and cyanuric acid are fully reacted in cardanol and improving the reaction efficiency and product purity. In addition, ball milling can further reduce the particle size of melamine and cyanuric acid, thereby increasing the specific surface area and surface defects, thereby further improving the reaction activity.

[0032] Specifically, when performing step S1, the molar ratio of melamine to cyanuric acid is 1:(0.8-1.2). In fact, under ideal conditions, the molar ratio of melamine to cyanuric acid during the reaction is 1:1, but due to the limitation of the reaction process, the amount of cyanuric acid can be adjusted to promote the full reaction of melamine, and to avoid excessive melamine and cyanuric acid remaining in the product, which causes inconvenience in separation.

[0033] At the same time, when executing step S1, when the molar ratio of melamine to cyanuric acid is 1:(0.8-1.2), the crystal structure of the formed melamine cyanurate is more regular, its thermal stability is higher, and thus the flame retardancy is relatively more guaranteed. At the same time, the melamine cyanurate with a more regular structure can interact better with cardanol, thereby improving the modification effect of cardanol on melamine cyanurate.

[0034] Specifically, when performing step S1, melamine and cyanuric acid are mixed and then ball-milled at 100-150° C. In fact, ball-milling in a temperature environment higher than the reaction temperature is conducive to the pre-combination reaction of melamine and cyanuric acid to generate melamine cyanurate initial product, and can also improve the molecular activity of melamine and cyanuric acid and thus improve the reaction intensity, and reduce the particle fineness of melamine and cyanuric acid, thereby promoting the contact modification of melamine, cyanuric acid and cardanol.

[0035] Specifically, when performing step S1, after melamine and cyanuric acid are mixed, they are ball-milled for 5-8 hours at a ball-to-material ratio of (15-25): 1. In fact, by grinding melamine and cyanuric acid with a high ball-to-material ratio, it is beneficial to refine the particles of melamine and cyanuric acid. At the same time, the high-energy collision generated during the ball milling process can improve the crystal shape of the melamine cyanurate initial product generated by the pre-combination reaction, and its specific surface area can be increased after refinement, which is beneficial to the modification treatment of cardanol.

[0036] In fact, when performing step S2, the temperature range of 70-90°C can provide suitable energy conditions for the reaction of melamine and cyanuric acid, which is conducive to the formation of melamine cyanurate. In addition, it can also promote the cardanol molecules to modify melamine cyanurate, thereby generating modified melamine cyanurate. In addition, controlling the reaction time is conducive to improving the product yield, so that the modification effect of the cardanol molecules on melamine cyanurate reaches a relatively stable state, thereby improving the structural stability of the modified melamine cyanurate.

[0037] In some embodiments, the mass volume ratio of the mixed powder to cardanol in step S2 is 0.08-0.10 g / mL. In fact, within this range, the mixed powder is evenly dispersed in cardanol, and the degree of modification of melamine cyanurate by cardanol molecules is controlled to avoid affecting the flame retardant properties of melamine cyanurate.

[0038] In some embodiments, in step S2, the mixed powder is added to cardanol and stirred and soaked for 30-60 minutes before ball milling. In fact, pre-soaking the mixed powder in cardanol is conducive to the diffusion of the mixed powder in cardanol, which can not only avoid agglomeration, but also make melamine and cyanuric acid contact with cardanol uniformly, avoiding the mixed powder that is not in contact with cardanol, thereby affecting the modification efficiency and modification effect.

[0039] In addition, in step S2, the mixed powder is added to the cardanol for ultrasonic dispersion and then ball milling is performed. In fact, the cavitation effect and mechanical vibration effect of ultrasound can promote the rapid dispersion of the mixed powder in the cardanol, and in this process, the tiny bubbles adhering to the surface of the mixed powder are caused to break, thereby increasing the contact area between the mixed powder and the cardanol, and at the same time, the cardanol molecules can be caused to penetrate into the interior of the mixed powder, thereby improving the uniformity and reaction efficiency of the reaction.

[0040] In some embodiments, in step S2, the mixed powder is added to the cardanol and ball-milled at 100-150° C. In this way, high-energy ball milling can be performed on melamine, cyanuric acid, melamine cyanuric acid initial product and cardanol molecules, thereby increasing the intensity of molecular motion, thereby accelerating the synthesis of melamine cyanurate initial product, and enabling the cardanol molecules to modify the melamine cyanurate initial product. At the same time, ball milling and blending within the range of 100-150° C. can improve the fluidity of cardanol, promote cardanol to better wrap the mixed powder, and thereby improve the modification efficiency and modification effect.

[0041] In some embodiments, in step S2, the mixed powder is ball-milled in cardanol for 3-5 hours, so that the mixture can be fully reacted and mixed with cardanol. In fact, in the early stage of ball milling, the mixed powder particles and cardanol are initially contacted and mixed. As the ball milling process proceeds, the reaction of melamine and cyanuric acid gradually proceeds, and the modification effect of cardanol on the generated melamine cyanurate initial product is also continuously enhanced. At the same time, long-term ball milling helps to further refine and evenly disperse melamine, cyanuric acid, and modified melamine cyanurate initial products in the mixed powder.

[0042] In some embodiments, in step S2, after the mixed powder is added to the cardanol for ball milling, ultrasonic mixing is performed at a frequency of 10-30kHz for 10-15 minutes. In fact, since the mixed powder is prone to form micro-agglomerates after the cardanol is ball milled, ultrasonic mixing helps to break up the agglomerates, thereby promoting the uniform dispersion of solid particles in the mixed slurry, which helps to improve the modification effect.

[0043] Specifically, the reaction in step S3 within 70-90° C. can promote the formation of melamine cyanurate, and promote the complete combination of melamine cyanurate initial substances to form melamine cyanurate, and is conducive to the stable modification and addition treatment of melamine cyanurate by cardanol molecules. At the same time, by controlling the reaction market, the modified melamine cyanurate formed by the combination of cardanol molecules and melamine cyanurate is promoted to reach a stable state, which is conducive to improving the quality consistency of the modified product.

[0044] In some embodiments, in step S3, the mixed slurry is heated to 70-90°C at a rate of 1-5°C / min, which is beneficial to controlling the temperature of the mixed slurry and the reaction process. At the same time, the mixed slurry can be evenly heated to avoid excessive local temperature caused by excessive heating, which affects the reaction uniformity and product quality. In addition, the cardanol molecules can be evenly activated, thereby improving the modification effect and modification rate of the cardanol molecules on melamine cyanurate.

[0045] In some embodiments, in step S3, the mixed slurry is kept warm at 70-90°C and stirred at a speed of 100-150 rpm for reaction. In fact, by keeping the mixed slurry warm, the reactivity of each substance in the mixed slurry can be improved, and high-speed stirring can make the mixed slurry maintain a uniform state during the reaction. In addition, not using ultrasonic treatment is conducive to the interaction and binding of cardanol molecules and melamine cyanurate.

[0046] In some embodiments, in step S3, after the mixed slurry is kept at 70-90°C, an inert gas is introduced into the bottom of the mixed slurry for bubbling and stirring the reaction. In fact, introducing an inert gas into the bottom of the mixed slurry can play a stirring role, and the mixed slurry is continuously flowed and mixed during the rising process of the inert gas, thereby ensuring uniform distribution of the components, accelerating the contact and reaction between the reactants, and thus improving the modification effect of cardanol on melamine cyanurate.

[0047] In some embodiments, in step S3, the supernatant is removed and the precipitate is separated after centrifugation at a speed of 200-300 rpm and standing for 30-40 minutes. In fact, the centrifugal speed of 200-300 rpm can provide sufficient centrifugal force, so that the modified melamine cyanurate prepared in the mixed slurry is precipitated to the bottom of the centrifuge tube, while the remaining impurities are located in the upper layer of the centrifuge tube, and the precipitation of the modified melamine cyanurate is facilitated during the standing process, thereby completing the separation.

[0048] In some embodiments, in step S3, after centrifugation at a speed of 200-300 rpm, the supernatant is removed, and deionized water is added for centrifugal washing to separate the precipitate. In fact, by adding deionized water for washing, impurities on the surface of the modified melamine cyanurate can be removed, and the purity of the obtained modified melamine cyanurate can be further improved.

[0049] In some embodiments, in step S3, the separated precipitate is dried in a vacuum environment at 80-100°C, and then ground, crushed and sieved to obtain modified melamine cyanurate. In fact, by drying at 80-100°C, the rapid evaporation of water in the precipitate can be accelerated, and the vacuum environment can prevent the modified melamine cyanurate from oxidative denaturation at high temperature, which is beneficial to improving the stability of the flame retardant properties of the modified melamine cyanurate. In addition, the separated precipitate can be ground and sieved in advance, and then placed in a vacuum environment at 80-100°C for drying to obtain the modified melamine cyanurate.

[0050] Specifically, in the melamine cyanurate flame retardant, the filler used is aluminum hydroxide, and the compatibilizer used is KH-550 coupling agent.

[0051] In fact, the present invention provides a method for preparing a melamine cyanurate flame retardant, comprising the following steps: grinding and blending modified melamine cyanurate, a filler and a compatibilizer to obtain a flame retardant. Specifically, grinding and blending the three components is conducive to fully mixing the modified melamine cyanurate with the filler and the compatibilizer, thereby improving the dispersibility and compatibility of the flame retardant during application. In addition, the average particle size of the flame retardant is 100-500nm.

[0052] The present invention also provides an application of a flame retardant, which can be applied to a polymer material to prepare a flame-retardant polymer material, and the mass addition ratio of the flame retardant in the polymer material is 3-5%.

[0053] Preparation Example 1 This preparation example 1 provides a method for preparing modified melamine cyanurate, comprising the following steps: S1. Melamine (CAS: 108-78-1) and cyanuric acid (CAS: 108-80-5) were mixed at a molar ratio of 1:1.2 and added into a ball mill. Zirconia was used as the ball milling ball, and the ball-to-material ratio was set to 20:1. The mixed material in the ball milling jar was ball milled at 120°C for 6 hours, and then cooled to room temperature to obtain a mixed powder. S2. Add cardanol (CAS: 501-26-8, purchased from Shanghai Pupu Biopharmaceutical Technology Co., Ltd.) to the mixed powder and adjust the solid-liquid ratio to 0.09 g / mL. Disperse the mixture by ultrasonication at a frequency of 20 kHz for 10 min, stir and soak at a speed of 200 rpm for 40 min, transfer the solid-liquid mixture to a ball mill, use zirconium oxide as a ball mill, and mix at 120°C for 6 h at a ball-to-material ratio of 20:1. Then, take out the mixture and mix it by ultrasonication at a frequency of 20 kHz for 15 min to obtain a mixed slurry. S3. The mixed slurry was heated from room temperature to 80°C at a rate of 5°C / min, kept at 80°C and nitrogen was introduced into the bottom of the mixed slurry at a flow rate of 100 mL / min, and mechanical stirring was applied at 100 rpm for 4 hours. The reaction system was transferred to a centrifuge tube, centrifuged at 250 rpm, and then allowed to stand for 30 minutes, and then the supernatant was removed. After separation of the precipitate, it was dried in a vacuum drying oven at 100°C to constant weight, and then ground, crushed and sieved to obtain modified melamine cyanurate.

[0054] Preparation Example 2 Preparation Example 2 provides a method for preparing modified melamine cyanurate, which is different from Preparation Example 1 in that an equal amount of phenol solution is used to replace cardanol in step S2.

[0055] Preparation Example 3 Preparation Example 3 provides a method for preparing modified melamine cyanurate, which is different from Preparation Example 1 in that an equal amount of deionized water is used to replace cardanol in step S2.

[0056] Example 1 to Example 3 Embodiments 1 to 3 of the present invention respectively provide a melamine cyanurate flame retardant using the modified melamine cyanurate prepared in Preparation Example 1, which specifically includes the components and amounts shown in Table 1.

[0057] Table 1 Components and dosages of Examples 1 to 3

[0058] Among them, the filler used in Examples 1 to 3 is aluminum hydroxide, and the compatibilizer used is KH-550 coupling agent. In addition, the preparation method of the melamine cyanurate flame retardant in Examples 1 to 3 includes the following steps: after the modified melamine cyanurate, the filler and the compatibilizer are mixed, they are put into a ball mill and zirconium oxide is used as a ball milling ball, and after the ball-to-material ratio is set to 20:1, the flame retardant with an average particle size of 500 nm is obtained after ball milling and blending at 80°C for 5 hours.

[0059] Comparative Example 1 This comparative example 1 provides a melamine cyanurate flame retardant, which is different from Example 2 in that the modified melamine cyanurate prepared in Preparation Example 2 is used in Comparative Example 1.

[0060] Comparative Example 2 This comparative example 2 provides a melamine cyanurate flame retardant, which is different from Example 2 in that the modified melamine cyanurate prepared in Preparation Example 3 is used in Comparative Example 2.

[0061] Performance Testing The melamine cyanurate flame retardant prepared in Examples 1 to 3 and Comparative Examples 1 to 2 was added to nylon at a mass ratio of 5%, and after extrusion injection molding at 220° C. using a twin-screw extruder, tensile strength, elongation at break and flame retardancy were tested. The results are shown in Table 2 below.

[0062] Table 2 Performance test results

[0063] The melamine cyanurate flame retardant prepared in Examples 1 to 3 and Comparative Examples 1 to 2 was added to nylon at a mass ratio of 5%, and extruded and injection molded at 220°C using a twin-screw extruder. After aging treatment for 48 hours in an aging test box at 80°C and an oxygen content of 40%, the tensile strength and elongation at break were tested, and the tensile strength attenuation values ​​and the elongation at break attenuation values ​​before and after aging were calculated, as shown in Table 3 below.

[0064] Table 3 Performance test results after aging test

[0065] It can be seen from Table 2 and Table 3 that when the modified melamine cyanurate provided by the present invention is added to a flame retardant and added to a polymer for flame retardant application, the flame retardant properties of the polymer can be greatly improved. At the same time, since the modified melamine cyanurate has better compatibility and dispersibility in the polymer, the mechanical properties and anti-aging properties of the polymer can be improved.

[0066] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A melamine cyanurate flame retardant, characterized in that: The modified melamine cyanurate comprises 60-80 parts of modified melamine cyanurate, 10-15 parts of filler and 5-10 parts of compatibilizer in parts by mass. The preparation method of the modified melamine cyanurate comprises: mixing melamine and cyanuric acid at a molar ratio of 1:(0.8-1.2) at 100-150° C. and ball milling for 5-8 hours to obtain a mixed powder; adding the mixed powder into cardanol and ball milling and then ultrasonically dispersing to obtain a mixed slurry; keeping the mixed slurry at 70-90° C. and stirring for reaction for 3-5 hours, centrifuging at a speed of 200-300 rpm to separate the precipitate, and then drying and crushing to obtain the modified melamine cyanurate.

2. The flame retardant according to claim 1, characterized in that: After the melamine and the cyanuric acid are mixed, they are ball milled at a ball-to-material ratio of (15-25):

1.

3. The flame retardant according to claim 1, characterized in that: The mass volume ratio of the mixed powder to the cardanol is 0.08-0.10 g / mL; and / or, the mixed powder is added to the cardanol, stirred and infiltrated for 30-60 minutes, and then ball-milled; and / or, the mixed powder is added to the cardanol, ultrasonically dispersed, and then ball-milled; and / or, the mixed powder is added to the cardanol and ball-milled at 100-150° C.; and / or, the mixed powder is added to the cardanol and ball-milled for 3-5 hours; and / or, after the mixed powder is added to the cardanol and ball-milled, it is ultrasonically mixed at a frequency of 10-30 kHz for 10-15 minutes.

4. The flame retardant according to claim 1, characterized in that: The mixed slurry is heated to 70-90°C at a rate of 1-5°C / min; and / or, the mixed slurry is kept at 70-90°C and stirred at a rotation speed of 100-150rpm for reaction; and / or, after the mixed slurry is kept at 70-90°C, an inert gas is introduced into the bottom of the mixed slurry for bubbling and stirring the reaction.

5. The flame retardant according to claim 1, characterized in that: After centrifugation at 200-300 rpm and standing for 30-40 min, the supernatant is removed and the precipitate is separated; and / or, after centrifugation at 200-300 rpm, the supernatant is removed, and deionized water is added for centrifugal washing to separate the precipitate.

6. The flame retardant according to claim 1, characterized in that: The separated precipitate is dried in a vacuum environment at 80-100° C., then ground, crushed and sieved to obtain modified melamine cyanurate; or, the separated precipitate is ground, sieved and then dried in a vacuum environment at 80-100° C. to obtain modified melamine cyanurate.

7. The flame retardant according to claim 1, characterized in that: The filler is aluminum hydroxide; and / or the compatibilizer is KH-550 coupling agent.

8. A method for preparing a flame retardant according to any one of claims 1 to 7, characterized in that: The following steps are involved: The flame retardant is prepared by grinding and blending modified melamine cyanurate, a filler and a compatibilizer.

9. Use of the flame retardant according to any one of claims 1 to 7.

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