Supramolecular assembled magnesium hydroxide whisker flame retardant and preparation method thereof

Abstract

The invention provides a supramolecular assembled magnesium hydroxide whisker flame retardant, which is formed by assembling magnesium hydroxide whiskers, phytic acid, micromolecular nitrogen-containing biomass and transition metal ions, the phytic acid is grafted on the magnesium hydroxide whiskers through hydrogen bonds, the micromolecular nitrogen-containing biomass is assembled on the phytic acid through static electricity and hydrogen bonds, and the transition metal ions are grafted on the micromolecular nitrogen-containing biomass through transition metal ions. The transition metal ions are complexed with phosphate groups on the phytic acid through coordinate bonds. The supramolecular assembled magnesium hydroxide whisker flame retardant is good in flame retardant effect and smoke suppression effect, and the preparation method is simple.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardant materials, and particularly relates to a supramolecular assembled magnesium hydroxide whisker flame retardant and a preparation method thereof. Background Art

[0002] Magnesium hydroxide is an inorganic flame retardant with broad application prospects. Its flame retardant mechanism mainly relies on the endothermic effect and the generation of water during the thermal decomposition process. Compared with aluminum hydroxide, magnesium hydroxide has a higher decomposition temperature and better smoke suppression ability. It is not only environmentally friendly, low-smoke, non-toxic, but also the magnesium oxide generated after decomposition has stable chemical properties and will not cause secondary pollution. However, the flame retardant efficiency of magnesium hydroxide is relatively low. Usually, a relatively high addition amount is required to achieve an effect comparable to that of traditional flame retardants, which will lead to a decline in the mechanical properties of the composite material. In addition, magnesium hydroxide is prone to agglomeration in the polymer matrix, which affects its uniform dispersion in the material, thereby having an adverse impact on the flame retardant performance and mechanical properties of the composite material.

[0003] To improve the flame retardant effect of magnesium hydroxide, morphology control and surface modification of magnesium hydroxide are commonly used methods in research. Studies have shown that magnesium hydroxide with a specific morphology can be synthesized by controlling the synthesis conditions of magnesium hydroxide (reactant concentration, reaction temperature, reaction time, precipitant type, etc.). Among them, magnesium hydroxide whiskers with a fibrous special morphology have lower surface energy and higher aspect ratio, and exhibit more excellent properties compared with magnesium hydroxide of other morphologies. There are also many studies on modifying magnesium hydroxide with modifiers to improve its flame retardant performance, but its flame retardant effect still needs to be improved, and the agglomeration situation of the modified flame retardant in polymer materials has not been improved.

[0004] Modifying magnesium hydroxide to improve its flame retardant effect and to improve the agglomeration situation of magnesium hydroxide in the polymer matrix is the key to further expanding the research and application of magnesium hydroxide. Summary of the Invention

[0005] To solve the problems existing in the background art, the present invention provides a supramolecular assembled magnesium hydroxide whisker flame retardant and a preparation method thereof. The supramolecular assembled magnesium hydroxide whisker flame retardant has good flame retardant and smoke suppression effects, high compatibility in polymer materials, and a simple preparation method.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] In a first aspect, the present invention provides a supramolecular assembled magnesium hydroxide whisker flame retardant, which is formed by assembling magnesium hydroxide whiskers, phytic acid, small molecule nitrogen-containing biomass, and transition metal ions. The phytic acid is grafted onto the magnesium hydroxide whiskers through hydrogen bonds, the small molecule nitrogen-containing biomass is assembled onto the phytic acid through electrostatic and hydrogen bonds, and the transition metal ions are complexed with the phosphate groups on the phytic acid through coordination bonds.

[0008] According to the above solution, the small molecule nitrogen-containing biomass is one or more of allantoin, adenosine, and dopamine.

[0009] According to the above solution, the transition metal ions are one or more of iron ions, cobalt ions, and nickel ions.

[0010] In a second aspect, the present invention provides a preparation method of the above supramolecular assembled magnesium hydroxide whisker flame retardant, which includes the following steps:

[0011] S1. Dissolve phytic acid and small molecule nitrogen-containing biomass in water to obtain a mixed solution of phytic acid and small molecule nitrogen-containing biomass;

[0012] S2. Add magnesium hydroxide whiskers to deionized water, heat and ultrasonically disperse to obtain a magnesium hydroxide whisker dispersion;

[0013] S3. Mix and react the transition metal ion source compound with the magnesium hydroxide whisker dispersion and the mixed solution of phytic acid and small molecule nitrogen-containing biomass, filter and dry to obtain the supramolecular assembled magnesium hydroxide whisker flame retardant.

[0014] According to the above solution, the dissolution temperature in step S1 is 60 - 80 °C, and the time is 1.5 - 2.5 h. The reaction temperature in step S3 is 80 - 90 °C, and the reaction time is 1.5 - 3.5 h.

[0015] According to the above solution, the transition metal ion source compound is one or more of ferric chloride, cobalt nitrate, and nickel nitrate.

[0016] According to the above solution, the molar ratio of the transition metal elements in the magnesium hydroxide whiskers, phytic acid, small molecule nitrogen-containing biomass, and transition metal ion source compound is 5:0.8 - 2.7:5 - 15:2 - 6.3.

[0017] According to the above solution, in step S3, the transition metal ion source compound can be added to the magnesium hydroxide whisker dispersion to dissolve the transition metal ion source compound, and then mixed and reacted with the mixed solution of phytic acid and small molecule nitrogen-containing biomass. Alternatively, the transition metal ion source compound can be added to the mixed solution of phytic acid and small molecule nitrogen-containing biomass to dissolve and then mixed with the magnesium hydroxide whisker dispersion for reaction.

[0018] According to the above solution, the magnesium hydroxide whiskers are prepared by the following steps:

[0019] 1) Dissolve magnesium chloride hexahydrate in deionized water, heat with vigorous stirring to obtain a magnesium chloride solution;

[0020] 2) Slowly add ammonia water to the magnesium chloride solution for the first reaction, carry out aging at a constant temperature, filter, and wash to obtain a basic magnesium chloride intermediate;

[0021] 3) Add the basic magnesium chloride intermediate to an ethanol aqueous solution, heat to obtain a slurry;

[0022] 4) Add an alkaline solution to the slurry for the second reaction, filter, wash, and dry to obtain the magnesium hydroxide whiskers.

[0023] According to the above scheme, in step 1), the temperature for dissolving magnesium chloride hexahydrate in deionized water and heating with stirring is 45 - 55 °C, and the time is 15 - 30 min.

[0024] In step 2), the temperature of the first reaction is 45 - 55 °C, the time is 1 - 2 h, and continuous stirring is carried out during the reaction. The temperature for aging at a constant temperature is 45 - 55 °C, and the time is 45 - 50 h.

[0025] According to the above scheme, in step 3), the temperature for heating when adding the basic magnesium chloride intermediate to the ethanol aqueous solution is 55 - 65 °C.

[0026] According to the above scheme, in step 4), the temperature of the second reaction is 50 - 60 °C, and the time is 1 - 1.5 h.

[0027] In the above preparation method, first mix and assemble phytic acid and small - molecule nitrogen - containing biomass, then add magnesium hydroxide whiskers and transition metal ion source compounds for further assembly to obtain a supramolecular - assembled magnesium hydroxide whisker flame retardant. Among them, phytic acid is grafted onto the magnesium hydroxide whiskers through hydrogen bonds, small - molecule nitrogen - containing biomass is assembled onto phytic acid through electrostatic and hydrogen bonds, and transition metal ions are complexed with the phosphate groups on phytic acid through coordination bonds. Further preferably in the method, the molar ratio of magnesium hydroxide whiskers, phytic acid, small - molecule nitrogen - containing biomass, and transition metal element in the transition metal ion source compound is 5:0.8 - 2.7:5 - 15:2 - 6.3.

[0028] In the third aspect, the present invention provides a flame - retardant organic material, including the above - mentioned supramolecular - assembled magnesium hydroxide whisker flame retardant.

[0029] Specifically, the flame - retardant organic material includes an organic material matrix, a supramolecular - assembled magnesium hydroxide whisker flame retardant, and a curing agent.

[0030] According to the above scheme, the addition amount of the supramolecular - assembled magnesium hydroxide whisker flame retardant is 5% - 35%.

[0031] The principle of the present invention is:

[0032] In the present invention, phytic acid, small molecule nitrogen-containing biomass and transition metals are introduced into magnesium hydroxide whiskers, and finally a flame retardant system integrating acid source, gas source and catalytic carbonization is assembled. When the matrix material containing the supramolecular assembled magnesium hydroxide whisker flame retardant burns, on the one hand, the flame retardant decomposes to produce phosphates, polyphosphates, etc. to promote the initial carbonization of the polymer. The transition metal ions play a catalytic carbonization synergistic effect to further promote the formation of the carbon layer. The flame retardant decomposes to produce non-combustible gases such as ammonia and water to promote the expansion of the carbon layer, further separating the formed carbon layer from the protected matrix. At the same time, the flame retardant decomposes and reacts during the combustion process. The transition metal ions finally exist as stable metal oxides and metal salts, which together with the high melting point and stable magnesium oxide produced by decomposition play a role in strengthening the carbon layer. These jointly promote the formation of a more stable and cross-linked carbon layer with higher purity, delay the subsequent combustion process, better protect the matrix, and at the same time exhibit excellent smoke suppression effect, achieving better flame retardant and smoke suppression effects; on the other hand, the flame retardant decomposes to produce non-combustible gases such as ammonia and water, isolating the heat and oxygen in the combustion area. At the same time, the flame retardant can also decompose to generate some phosphorus-containing free radicals to capture the active free radicals and interrupt the combustion chain reaction, slowing down the combustion progress.

[0033] The beneficial effects of the present invention are as follows:

[0034] 1. The supramolecular assembled magnesium hydroxide whisker flame retardant of the present invention forms a flame retardant system integrating acid source, gas source and catalytic carbonization through the supramolecular assembly of magnesium hydroxide whiskers, phytic acid, small molecule nitrogen-containing biomass and transition metals. The components act synergistically, having excellent flame retardant effect and smoke suppression performance;

[0035] 2. The flame retardant system of the present invention improves the compatibility between the flame retardant and the organic matrix, makes the flame retardant evenly dispersed in the organic matrix, and significantly improves the agglomeration phenomenon, further improving its flame retardant performance;

[0036] 3. The modifier used in the supramolecular assembled magnesium hydroxide whisker flame retardant of the present invention has degradability, is green and pollution-free, environmentally friendly, and has low cost;

[0037] 4. Using the supramolecular assembly method to prepare the flame retardant system has the characteristics of controllable structure, good stability, mild reaction conditions and environmental friendliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is the synthesis route diagram of the supramolecular assembled magnesium hydroxide whisker flame retardant of the present invention;

[0039] Figure 2 It is the XRD diffraction pattern of the magnesium hydroxide whisker flame retardant prepared by the present invention;

[0040] Figure 3 SEM scanning image of the magnesium hydroxide whisker flame retardant prepared by the present invention;

[0041] Figure 4 SEM scanning image of the supramolecular assembled magnesium hydroxide whisker flame retardant prepared in Example 1 of the present invention;

[0042] Figure 5 SEM scanning image of the char layer after combustion of the epoxy resin sample prepared in the blank control group of the present invention;

[0043] Figure 6 SEM scanning image of the char layer after combustion of the flame-retardant epoxy resin sample prepared in Control Group 1 of the present invention;

[0044] Figure 7 SEM scanning image of the char layer after combustion of the flame-retardant epoxy resin sample prepared in Experimental Group 3 of the present invention;

[0045] Figure 8 SEM scanning image of the liquid nitrogen brittle fracture surface of the flame-retardant epoxy resin sample prepared in Experimental Group 3 of the present invention;

[0046] Figure 9 SEM scanning image of the liquid nitrogen brittle fracture surface of the flame-retardant epoxy resin sample prepared in Control Group 1 of the present invention. Detailed implementation manners

[0047] The principles and features of the present invention will be described below in conjunction with the accompanying drawings and specific embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0048] In a first aspect, the present invention provides a supramolecular assembled magnesium hydroxide whisker flame retardant, which is formed by assembling magnesium hydroxide whiskers, phytic acid, small molecule nitrogen-containing biomass, and transition metal ions. The phytic acid is grafted onto the magnesium hydroxide whiskers through hydrogen bonds, the small molecule nitrogen-containing biomass is assembled onto the phytic acid through electrostatic and hydrogen bonds, and the transition metal ions are complexed with the phosphate groups on the phytic acid through coordination bonds.

[0049] In some specific embodiments, the small molecule nitrogen-containing biomass is one or more of allantoin, adenosine, and dopamine.

[0050] In some specific embodiments, the transition metal ions are one or more of iron ions, cobalt ions, and nickel ions.

[0051] In some specific embodiments, the molar ratio of the magnesium hydroxide whiskers, phytic acid, small molecule nitrogen-containing biomass, and transition metal ions is 5:0.8 - 2.7:5 - 15:2 - 6.3.

[0052] Second aspect, the present invention provides a preparation method of the above-mentioned supramolecular assembled magnesium hydroxide whisker flame retardant, and its synthetic route diagram is as Figure 1 shown. This figure is only for explaining the assembly principle and steps of the supramolecular assembled magnesium hydroxide whisker flame retardant, and is not used to illustrate the proportion of each component. The method includes the following steps:

[0053] S1. Dissolve phytic acid and small molecule nitrogen-containing biomass in water to obtain a mixed solution of phytic acid and small molecule nitrogen-containing biomass;

[0054] S2. Add magnesium hydroxide whiskers into deionized water, heat and ultrasonically disperse to obtain a magnesium hydroxide whisker dispersion;

[0055] S3. Mix and react the transition metal ion source compound with the magnesium hydroxide whisker dispersion and the mixed solution of phytic acid and small molecule nitrogen-containing biomass, filter and dry to obtain the supramolecular assembled magnesium hydroxide whisker flame retardant.

[0056] In some specific embodiments, the dissolution temperature in step S1 is 60-80 °C, and the time is 1.5-2.5 h.

[0057] In some specific embodiments, the reaction temperature in step S3 is 80-90 °C, and the reaction time is 1.5-3.5 h.

[0058] In some specific embodiments, the transition metal ion source compound is one or more of ferric chloride, cobalt nitrate and nickel nitrate.

[0059] In some specific embodiments, the molar ratio of magnesium hydroxide whiskers, phytic acid, small molecule nitrogen-containing biomass and transition metal is: 5:0.8-2.7:5-15:2-6.3.

[0060] In some specific embodiments, in step S3, the transition metal ion source compound can be added to the magnesium hydroxide whisker dispersion to dissolve the transition metal ion source compound, and then mixed and reacted with the mixed solution of phytic acid and small molecule nitrogen-containing biomass, or the transition metal ion source compound can be added to the mixed solution of phytic acid and small molecule nitrogen-containing biomass to dissolve and then mixed and reacted with the magnesium hydroxide whisker dispersion.

[0061] In some specific embodiments, the magnesium hydroxide whiskers are prepared by the following steps:

[0062] 1) Dissolve magnesium chloride hexahydrate in deionized water, heat and stir vigorously to obtain a magnesium chloride solution;

[0063] 2) Slowly add ammonia water to the magnesium chloride solution for the first reaction, keep the temperature constant for aging, filter and wash to obtain a basic magnesium chloride intermediate;

[0064] 3) Add the basic magnesium chloride intermediate to an aqueous ethanol solution and heat to obtain a slurry;

[0065] 4) Add an alkaline solution to the slurry for a second reaction, filter, wash, and dry to obtain the magnesium hydroxide whiskers.

[0066] In some specific embodiments, the magnesium hydroxide whiskers are prepared by the following steps:

[0067] 1) Dissolve magnesium chloride hexahydrate in deionized water, heat with vigorous stirring to obtain a magnesium chloride solution;

[0068] 2) Slowly add ammonia water to the magnesium chloride solution for a first reaction, carry out aging at a constant temperature, filter, and wash to obtain a basic magnesium chloride intermediate;

[0069] 3) Add the basic magnesium chloride intermediate to an aqueous ethanol solution and heat to obtain a slurry;

[0070] 4) Add an alkaline solution to the slurry for a second reaction, filter, wash, and dry to obtain the magnesium hydroxide whiskers.

[0071] In some specific embodiments, in step 1), the temperature for dissolving magnesium chloride hexahydrate in deionized water and heating with stirring is 45 - 55 °C, and the time is 15 - 30 min.

[0072] In step 2), the temperature of the first reaction is 45 - 55 °C, the time is 1 - 2 h, stirring is continuous during the reaction, the temperature for aging at a constant temperature is 45 - 55 °C, and the time is 45 - 50 h.

[0073] In some specific embodiments, in step 3), the temperature for adding the basic magnesium chloride intermediate to the aqueous ethanol solution and heating is 55 - 65 °C.

[0074] In some specific embodiments, in step 4), the temperature of the second reaction is 50 - 60 °C, and the time is 1 - 1.5 h.

[0075] In a third aspect, the present invention provides a flame - retardant organic material, comprising the above - mentioned supramolecular - assembled magnesium hydroxide whisker flame retardant.

[0076] In some specific embodiments, the flame - retardant organic material comprises an organic material matrix, a supramolecular - assembled magnesium hydroxide whisker flame retardant, and a curing agent.

[0077] In some specific embodiments, the addition amount of the supramolecular - assembled magnesium hydroxide whisker flame retardant is 5% - 35%.

[0078] The organic material matrix can be epoxy resin, polyurethane, polyethylene, etc.

[0079] In some specific embodiments, taking epoxy resin as the organic material matrix as an example, epoxy resin E51 is specifically used.

[0080] The following are specific embodiments.

[0081] In the following multiple embodiments, magnesium hydroxide whiskers are prepared by the following method: Dissolve 203.3 g of MgCl2·6H2O in 300 ml of deionized water, and stir vigorously at 60 °C for 30 min. Drop 15.8 ml of NH3·H2O with a mass fraction of 25% into the solution, stir the mixed solution at 40 °C for 1 h, age it in a water bath at 40 °C for 48 h, and obtain a basic magnesium chloride precursor through filtration and washing. Add the precursor to 200 ml of an ethanol aqueous solution with a volume fraction of 20%, and disperse it into a slurry at 60 °C. Add 114.3 ml of 3.5 mol / L NaOH solution to the slurry, and continue to react at 60 °C for 1 h. Wash with ethanol and deionized water respectively, and dry in an oven at 60 °C for 24 h to obtain magnesium hydroxide whiskers.

[0082] The XRD diffraction pattern of the prepared magnesium hydroxide whiskers is as Figure 2 shown. The XRD test results show that it basically coincides with the standard diffraction, confirming that the prepared sample is magnesium hydroxide whiskers; the SEM scanning image of the sample is as Figure 3 shown, showing that the sample has good whisker shape, the whisker diameter is equiaxed and uniform, the straight whisker rate is good, the particle size distribution is uniform, the diameter is 0.1 - 1 μm, the aspect ratio is 60 - 70:1, and there is very little non-whisker-like substance and good dispersibility.

[0083] Example 1

[0084] Dissolve 9.48 g of allantoin in 200 ml of deionized water, stir vigorously at 80 °C to obtain a clear and transparent solution, dilute 10 g of a 70% mass fraction aqueous solution of phytic acid and add it to the solution, and stir at 80 °C for 2 h to obtain a mixed solution of allantoin and phytic acid. Take 2.9 g of magnesium hydroxide whiskers and add them to 200 ml of deionized water, disperse them ultrasonically for 15 min, take 4.36 g of anhydrous ferric chloride and add it to the solution, stir vigorously at 80 °C, add the mixed solution of allantoin and phytic acid, and continue to react at 80 °C for 2 h. Filter, wash, and dry in an oven at 80 °C for 24 h to obtain supramolecular assembled magnesium hydroxide whisker flame retardant - I.

[0085] The SEM scanning image of the supramolecular assembled magnesium hydroxide whisker flame retardant prepared in this example is as Figure 4 shown. A supramolecular assembly layer can be observed on the surface of the magnesium hydroxide whiskers, indicating successful assembly.

[0086] Example 2

[0087] Dissolve 18.96 g of allantoin in 200 ml of deionized water, and stir vigorously at 80 °C to obtain a clear and transparent solution. Dilute 10 g of a 70% by mass aqueous solution of phytic acid and add it to the solution, and stir at 80 °C for 2 h to obtain a mixed solution of allantoin and phytic acid. Take 2.9 g of magnesium hydroxide whiskers and add them to 200 ml of deionized water, ultrasonically disperse for 15 min, take 4.36 g of anhydrous ferric chloride and add it to the solution, stir vigorously at 80 °C, add the mixed solution of allantoin and phytic acid, and continue to react at 80 °C for 2 h. Filter, wash, and dry in an oven at 80 °C for 24 h to obtain supramolecular assembled magnesium hydroxide whisker flame retardant - II.

[0088] Example 3

[0089] Dissolve 9.48 g of allantoin in 200 ml of deionized water, and stir vigorously at 80 °C to obtain a clear and transparent solution. Dilute 10 g of a 70% by mass aqueous solution of phytic acid and add it to the solution, and stir at 80 °C for 2 h to obtain a mixed solution of allantoin and phytic acid. Take 2.9 g of magnesium hydroxide whiskers and add them to 200 ml of deionized water, ultrasonically disperse for 15 min, take 8.72 g of anhydrous ferric chloride and add it to the solution, stir vigorously at 80 °C, add the mixed solution of allantoin and phytic acid, and continue to react at 80 °C for 2 h. Filter, wash, and dry in an oven at 80 °C for 24 h to obtain supramolecular assembled magnesium hydroxide whisker flame retardant - III.

[0090] Example 4

[0091] Dissolve 23.7 g of allantoin in 200 ml of deionized water, and stir vigorously at 80 °C to obtain a clear and transparent solution. Dilute 25 g of a 70% by mass aqueous solution of phytic acid and add it to the solution, and stir at 80 °C for 2 h to obtain a mixed solution of allantoin and phytic acid. Take 2.9 g of magnesium hydroxide whiskers and add them to 200 ml of deionized water, ultrasonically disperse for 15 min, take 5.0 g of anhydrous ferric chloride and add it to the solution, stir vigorously at 80 °C, add the mixed solution of allantoin and phytic acid, and continue to react at 80 °C for 2 h. Filter, wash, and dry in an oven at 80 °C for 24 h to obtain supramolecular assembled magnesium hydroxide whisker flame retardant - IV.

[0092] Example 5

[0093] Dissolve 7.9 g of allantoin in 200 ml of deionized water, and vigorously stir at 80 °C to obtain a clear and transparent solution. Dilute 8 g of an aqueous solution of phytic acid with a mass fraction of 70% and add it to the solution, and stir at 80 °C for 2 h to obtain a mixed solution of allantoin and phytic acid. Take 2.9 g of magnesium hydroxide whiskers and add them to 200 ml of deionized water, ultrasonically disperse for 15 min, take 4.36 g of anhydrous ferric chloride and add it to the solution, vigorously stir at 80 °C, add the mixed solution of allantoin and phytic acid, and continue to react at 80 °C for 2 h. Filter, wash, and dry in an oven at 80 °C for 24 h to obtain supramolecular assembled magnesium hydroxide whisker flame retardant-V.

[0094] Example 6

[0095] Dissolve 9.48 g of allantoin in 200 ml of deionized water, and vigorously stir at 80 °C to obtain a clear and transparent solution. Dilute 20 g of an aqueous solution of phytic acid with a mass fraction of 70% and add it to the solution, and stir at 80 °C for 2 h to obtain a mixed solution of allantoin and phytic acid. Take 2.9 g of magnesium hydroxide whiskers and add them to 200 ml of deionized water, ultrasonically disperse for 15 min, take 10 g of anhydrous ferric chloride and add it to the solution, vigorously stir at 80 °C, add the mixed solution of allantoin and phytic acid, and continue to react at 80 °C for 2 h. Filter, wash, and dry in an oven at 80 °C for 24 h to obtain supramolecular assembled magnesium hydroxide whisker flame retardant-VI.

[0096] Example 7

[0097] Dissolve 16.02 g of adenosine in 200 ml of deionized water, and vigorously stir at 80 °C to obtain a clear and transparent solution. Dilute 20 g of an aqueous solution of phytic acid with a mass fraction of 70% and add it to the solution, and stir at 80 °C for 2 h to obtain a mixed solution of adenosine and phytic acid. Take 2.9 g of magnesium hydroxide whiskers and add them to 200 ml of deionized water, ultrasonically disperse for 15 min, take 10 g of anhydrous ferric chloride and add it to the solution, vigorously stir at 80 °C, add the mixed solution of adenosine nucleotide and phytic acid, and continue to react at 80 °C for 2 h. Filter, wash, and dry in an oven at 80 °C for 24 h to obtain supramolecular assembled magnesium hydroxide whisker flame retardant-VII.

[0098] Comparative Example 1

[0099] This comparative example provides a phytic acid-modified magnesium hydroxide whisker flame retardant, and the preparation method is as follows: Dilute 10 g of an aqueous solution of phytic acid with a mass fraction of 70% in deionized water to obtain 200 ml of an aqueous solution of phytic acid. Take 2.9 g of magnesium hydroxide whiskers and add them to 200 ml of deionized water, ultrasonically disperse for 15 min, add the aqueous solution of phytic acid, continue to react at 80 °C for 2 h, filter, wash, and dry in an oven at 80 °C for 24 h to obtain a phytic acid-modified magnesium hydroxide whisker flame retardant.

[0100] Table 1

[0101]

[0102]

[0103] Respectively, prepare flame-retardant epoxy resins using magnesium hydroxide whisker flame retardants, the flame retardants prepared in Examples 1-7 above, and the flame retardant prepared in Comparative Example 1. The specific preparation method is as follows: Add the flame retardant to the preheated epoxy resin, mechanically stir for 2 h, then add curing agent G593 to the reaction mixture. The addition amount of the flame retardant is 5% - 35%, preferably 10% - 20%. Stir and mix well and perform ultrasonic degassing. Subsequently, pour the mixture into a standard polytetrafluoroethylene mold, further perform vacuum degassing, and cure at room temperature for 12 h to obtain the flame-retardant epoxy resin. A blank control group (without adding any flame retardant) and other control groups are set up in the experiment, and different experimental groups are designed according to the addition amount of the flame retardant.

[0104] Test the limiting oxygen index (LOI) of the prepared flame-retardant epoxy resin. The experimental setup and test results are shown in Table 2 below:

[0105] Table 2

[0106]

[0107]

[0108] The limiting oxygen index (LOI) is one of the indicators for measuring the combustion performance of materials. A higher LOI value means that the material requires a higher concentration of oxygen to continue burning, usually indicating that the material has better flame retardant performance.

[0109] In Control Groups 1-3, 10, 15, and 20 g of phytic acid-modified magnesium hydroxide whisker flame retardants are added respectively. In Experimental Groups 1-3, 10, 15, and 20 g of supramolecular assembled magnesium hydroxide whisker flame retardant-I are added respectively. When the addition amount of the flame retardant is the same, regardless of the addition amount, the flame retardant effect of supramolecular assembled magnesium hydroxide whisker flame retardant-I is higher than that of phytic acid-modified magnesium hydroxide whisker flame retardant.

[0110] In Experimental Groups 3 - 9, the supramolecular assembled magnesium hydroxide whisker flame retardants - I to - VII prepared in Examples 1 - 7 were respectively added, with an addition amount of 20%. The LOIs of the resulting flame - retarded epoxy resins were 23.1, 22.7, 23, 23, 22.6, 22.9, and 22.8 respectively. Compared with the magnesium hydroxide whisker flame retardant added in Control Group 1 and the phytic acid - modified magnesium hydroxide whisker flame retardant added in Control Group 4, their LOIs are higher and the flame - retardant performance is better. This indicates that the supramolecular assembled magnesium hydroxide whisker flame retardant of the present invention, due to the synergistic effect of the components in the composite flame - retardant system assembled by magnesium hydroxide whiskers, phytic acid, small - molecule nitrogen - containing biomass, and transition metal ions, enhances the flame - retardant effect of the flame retardant. In the application of the flame retardant, when used for flame - retarding organic materials, it can reduce the usage amount of the flame retardant in the organic matrix material and increase the mechanical properties of the flame - retarded organic material.

[0111] Cone calorimeter tests (cone calorimeter tests under external heat radiation of 35 kW / m 2 ), LOI tests were carried out on the flame - retarded epoxy resin samples prepared from Experimental Groups 1 - 3, the blank control group, and Control Group 1 of the present invention, including the peak heat release rate (pHRR), total heat release (THR), peak smoke production rate (pSPR), total smoke release (TSP), and limiting oxygen index (LOI) under combustion conditions. The results are shown in Table 3.

[0112] Table 3 Cone calorimeter and LOI test results of each group of samples

[0113]

[0114] From the data measured in Table 3, the fire performance index and fire growth index of the samples can be further calculated, and the results are shown in Table 4. Among them, the fire performance index is the ratio of the ignition time of the material to the peak heat release rate. The higher the fire performance index, the lower the fire hazard; the fire growth index is the ratio of the peak heat release rate of the material during combustion to the time required to reach the peak. The larger the fire growth index of the material, the greater the fire hazard.

[0115] Table 4 Calculation results of fire performance index and fire growth index of each group of samples

[0116]

[0117] From the data in Table 3 and Table 4, it can be concluded that:

[0118] The performance test data of Experimental Group 3 and Control Group 1 show that the supramolecular assembled magnesium hydroxide whisker flame retardant of the present invention has a significant improvement in flame - retardant performance and smoke - suppression performance compared with ordinary magnesium hydroxide whisker flame retardants.

[0119] Compared with the blank control group, the performance test data of Experimental Groups 1-3 show that magnesium hydroxide flame retardant can effectively improve the fire resistance of polymer materials, reduce the smoke release amount and combustion rate during combustion, and has good flame retardant and smoke suppression effects. In Experimental Groups 1-3, as the content of supramolecular assembled magnesium hydroxide whiskers increases, the fire resistance of the samples improves, and the smoke release rate and combustion rate during combustion decrease.

[0120] SEM images of the char layers after combustion of the samples of the blank control group, Control Group 1, and Experimental Group 3 are respectively as Figure 5 , 6 and 7 shown. Combining Figures 5-7 it can be seen that the epoxy resin forms a fragmented and loose char layer after combustion; the sample prepared by adding magnesium hydroxide whiskers to the epoxy resin decomposes to form whisker-like magnesium oxide during combustion, which cannot promote the cross-linking of the char layer, and the density of the char layer is poor, and the protective effect is poor; the sample prepared by adding supramolecular assembled magnesium hydroxide whiskers to the epoxy resin can promote the formation of a dense char layer during combustion and better protect the matrix.

[0121] The addition amount of the prepared supramolecular assembled magnesium hydroxide whisker flame retardant of the present invention in the flame-retardant organic material is 5% - 35%, and good flame retardant effects can be obtained. More preferably, the addition amount is 10% - 20%.

[0122] SEM scans were performed on the liquid nitrogen brittle fracture surfaces of the samples prepared from Experimental Group 3 and Control Group 1. The results are respectively as Figure 8 and Figure 9 shown. It can be seen that the fracture surface of the sample prepared from Control Group 1 is rough, there is agglomeration of magnesium hydroxide whiskers in the epoxy resin, the dispersibility is poor, and the compatibility with the epoxy resin is poor. The fracture surface of the sample prepared from Experimental Group 3 is smooth, the flame retardant is more evenly dispersed in the matrix, and the interface becomes unclear. This shows that the biomass supramolecular assembled magnesium hydroxide whisker flame retardant significantly improves the compatibility between the flame retardant and the matrix, and the flame retardant is evenly dispersed in the epoxy resin matrix, and the agglomeration phenomenon is significantly improved, further improving the flame retardant performance of the flame retardant.

[0123] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A supramolecular assembled magnesium hydroxide whisker flame retardant, characterized in that, It is formed by the assembly of magnesium hydroxide whiskers, phytic acid, small-molecule nitrogen-containing biomass and transition metal ions. The phytic acid is grafted onto the magnesium hydroxide whiskers through hydrogen bonds. The small-molecule nitrogen-containing biomass is assembled onto the phytic acid through electrostatic and hydrogen bonds. The transition metal ions are complexed with the phosphate groups on the phytic acid through coordination bonds.

2. The supramolecular assembled magnesium hydroxide whisker flame retardant according to claim 1, wherein The small-molecule nitrogen-containing biomass is one or more of allantoin, adenosine and dopamine.

3. The supramolecular magnesium hydroxide whisker flame retardant according to claim 1, characterized in that, The transition metal ions are one or more of iron ions, cobalt ions and nickel ions.

4. The preparation method of the supramolecular assembled magnesium hydroxide whisker flame retardant according to any one of claims 1 to 3, characterized in that, It includes the following steps: S1. Dissolve phytic acid and small-molecule nitrogen-containing biomass in water to obtain a mixed solution of phytic acid and small-molecule nitrogen-containing biomass. S2. Add magnesium hydroxide whiskers to deionized water, heat and ultrasonically disperse to obtain a magnesium hydroxide whisker dispersion. S3. Mix the transition metal ion source compound with the magnesium hydroxide whisker dispersion and the mixed solution of phytic acid and small-molecule nitrogen-containing biomass for reaction, filter and dry to obtain the supramolecular assembled magnesium hydroxide whisker flame retardant.

5. The preparation method of the supramolecular assembled magnesium hydroxide whisker flame retardant according to claim 4, characterized in that, In step S1, the dissolution temperature is 60 - 80 °C and the time is 1.5 - 2.5 h. In step S3, the reaction temperature is 80 - 90 °C and the reaction time is 1.5 - 3.5 h.

6. The preparation method of the supramolecular assembled magnesium hydroxide whisker flame retardant according to claim 4, characterized in that, The molar ratio of the transition metal ions in the magnesium hydroxide whiskers, phytic acid, small-molecule nitrogen-containing biomass and transition metal ion source compound is 5:0.8 - 2.7:5 - 15:2 - 6.

3.

7. The preparation method of the supramolecular assembled magnesium hydroxide whisker flame retardant according to claim 4, characterized in that, The transition metal ion source compound is one or more of ferric chloride, cobalt nitrate and nickel nitrate.

8. The preparation method of the supramolecular assembled magnesium hydroxide whisker flame retardant according to claim 4, wherein, The transition metal ion source compound is one or more of ferric chloride, cobalt nitrate and nickel nitrate.

9. The preparation method of the supramolecular assembled magnesium hydroxide whisker flame retardant according to claim 4, wherein The magnesium hydroxide whiskers are prepared by the following steps: 1) Dissolve magnesium chloride hexahydrate in deionized water, heat and stir vigorously to obtain a magnesium chloride solution. 2) Slowly add ammonia water to the magnesium chloride solution for the first reaction, keep the temperature constant for aging, filter and wash to obtain a basic magnesium chloride intermediate. 3) Add the basic magnesium chloride intermediate to an ethanol aqueous solution, heat to obtain a slurry. 4) Add an alkaline solution to the slurry for the second reaction, filter, wash and dry to obtain the magnesium hydroxide whiskers.

10. A flame-retardant organic material, characterized in that, It includes the supramolecular assembled magnesium hydroxide whisker flame retardant according to any one of claims 1 - 4.

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