Nano magnesium hydroxide / black phosphorene compound flame retardant as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of inorganic flame retardants, and discloses a nano magnesium hydroxide / black phosphorene compound flame retardant as well as a preparation method and application thereof. The invention relates to a nano magnesium hydroxide / black phosphorene compound flame retardant, which comprises nano magnesium hydroxide and black phosphorene, the mass ratio of the nano magnesium hydroxide to the black phosphorene is (1-10): 1, and the compound flame retardant is added into an amino polydimethylsiloxane and epoxy resin composite material matrix. According to the invention, a compound flame retardant compounded by nano-scale hexagonal sheet magnesium hydroxide (MH) and black phosphorene (BP) is prepared by adopting an electrostatic self-assembly principle, when the addition amount is 1 wt% of BP and 4 wt% of MH, the composite material can reach the vertical combustion V-0 level, the limit oxygen index can reach 25.3-25.7%, the heat conductivity coefficient is greater than 1.6 W.m <-1 >. K <-1 >, and the flame retardant has good flame retardance. The problem that the mechanical property of the material is greatly reduced due to high addition amount of magnesium hydroxide is solved, and a new thought is provided for modifying black phosphorene.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic flame retardants, and in particular to a nano magnesium hydroxide / black phosphorene composite flame retardant and a preparation method and application thereof. Background Art

[0002] Flame retardants are widely used in the fields of construction, furniture, transportation, etc., and can significantly improve the safety of materials. However, other filler flame retardants such as halogen flame retardants release toxic gases during combustion, which affect human health and cause environmental damage, and there are environmental problems. Therefore, environmentally friendly inorganic flame retardants have become the focus of recent research. Magnesium hydroxide is a positively charged octahedral ionic crystal composed of magnesium ions and hydroxide ions. Magnesium hydroxide flame retardant has the advantages of halogen-free and smoke suppression, is environmentally friendly, and meets the requirements of modern industry for green and environmental protection. However, due to its low flame retardant efficiency, there is a disadvantage that high addition will greatly reduce the mechanical properties of the material. At the same time, the traditional method of preparing nano-magnesium hydroxide has problems such as long time period, low purity, and complex process, and the obtained particle size and particle size distribution are large, which affects the use effect. Black phosphorene is a two-dimensional layered structure in which phosphorus atoms are connected by covalent bonds and adjacent layers are connected by van der Waals forces. It can be processed by mechanical exfoliation, liquid phase exfoliation and other methods to obtain single-layer or few-layer phosphorene. As a more stable crystal than red phosphorus, it has certain advantages in flame retardant properties. However, the phosphorus atoms inside phosphorene have lone pairs of electrons and are negatively charged. They are easily deactivated by reaction with oxygen and have poor stability. They need to be modified, such as through argon protection, microencapsulation coating and other methods. However, there are problems such as high price, high cost, complicated operation and high energy consumption.

[0003] In view of the drawbacks of the complicated methods for preparing magnesium hydroxide flame retardant and black phosphorene modification in the prior art, a composite flame retardant with simple process and environmental friendliness is provided, which has broad application prospects. Summary of the invention

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a nano magnesium hydroxide / black phosphorene composite flame retardant.

[0005] Another object of the present invention is to provide a method for preparing a nano magnesium hydroxide / black phosphorene composite flame retardant.

[0006] Another object of the present invention is to provide an application of the above-mentioned nano magnesium hydroxide / black phosphorene composite flame retardant.

[0007] Another object of the present invention is to provide a flame retardant organic silicon composite material.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A nano magnesium hydroxide / black phosphorene composite flame retardant comprises nano magnesium hydroxide and black phosphorene, wherein the mass ratio of the nano magnesium hydroxide to the black phosphorene is 1 to 10:1.

[0010] Furthermore, the particle size of the nano magnesium hydroxide is 300-500nm;

[0011] Furthermore, the preparation method of the nano magnesium hydroxide is as follows:

[0012] (1) preparing a soluble magnesium salt solution and a precipitant aqueous solution respectively, preheating them respectively, continuously conveying the soluble magnesium salt solution and the precipitant aqueous solution respectively, and performing ultrasonic and mixing reactions to obtain a magnesium hydroxide nano-slurry;

[0013] (2) Ultrasonic dispersion of the magnesium hydroxide nano-slurry is performed, filtration is performed, and drying is performed to obtain nano magnesium hydroxide.

[0014] Furthermore, in step (1), the delivery flow rate of the soluble magnesium salt solution and the precipitant aqueous solution is equal to 150-180 mL / min, the delivery pressure is 0.2-0.3 MPa, and the power of the ultrasound is 100-200 W;

[0015] The concentration of the soluble magnesium salt solution is 1.0 mol / L-3.0 mol / L, and the ratio of the concentration of the soluble magnesium salt solution to the concentration of the precipitant aqueous solution is 1:2-3;

[0016] Furthermore, the preheating temperature in step (1) is 60-80°C;

[0017] The ultrasonic power in step (2) is 50-100w, and the ultrasonic time is 1-3h;

[0018] The soluble magnesium salt is magnesium chloride, magnesium sulfate or magnesium nitrate, and the precipitant is sodium hydroxide or potassium hydroxide.

[0019] Furthermore, the black phosphorene is prepared by a liquid phase exfoliation method, and the specific steps are as follows:

[0020] Black phosphorus is placed in a solvent, ultrasonicated, filtered and dried to obtain black phosphorene.

[0021] Further, the solvent is one of isopropanol, N-methylpyrrolidone, and anhydrous ethanol;

[0022] The ultrasonic power is 50-80w, and the ultrasonic time is 12-24h.

[0023] A method for preparing a nano magnesium hydroxide / black phosphorene composite flame retardant comprises the following steps:

[0024] Adding nano magnesium hydroxide and black phosphorene into a solvent, mixing, ultrasonicating, and performing electrostatic self-assembly to obtain a nano magnesium hydroxide / black phosphorene composite flame retardant;

[0025] The solvent is one of isopropanol, acetone and toluene, and the mixing time is 5-30 minutes;

[0026] The power of the ultrasound is 20-80w.

[0027] Application of the above-mentioned nano magnesium hydroxide / black phosphorene composite flame retardant in the preparation of flame retardant materials.

[0028] Furthermore, the application comprises the following steps:

[0029] Adding nano magnesium hydroxide / black phosphorene composite flame retardant to the base resin and curing to obtain a flame retardant material;

[0030] The addition amount of the nano magnesium hydroxide / black phosphorene composite flame retardant is 1-10wt% of the base resin.

[0031] Further, the curing temperature is 30°C-100°C, and the curing time is 3h-12h;

[0032] The matrix resin includes amino polydimethylsiloxane and epoxy resin in a mass ratio of 1-10:1.

[0033] Furthermore, the epoxy resin is epoxy resin E-51.

[0034] An organic silicon composite flame retardant material is prepared by the above application.

[0035] Preferably, the vertical combustion grade of the organic silicon composite flame retardant material is V-0, the limiting oxygen index is greater than 25%, and the thermal conductivity is greater than 1.6 W·m -1 ·K -1 .

[0036] The present invention compounds the environmentally friendly nano magnesium hydroxide flame retardant with black phosphorene through the principle of electrostatic self-assembly. Black phosphorene can promote the decomposition of magnesium hydroxide, increase the surface area of ​​the product magnesium oxide after combustion, and further enhance the flame retardant effect. Magnesium hydroxide can reduce the ignition temperature of black phosphorene, and prevent the spread of fire by releasing water and stabilizing the flame. The two work synergistically to achieve a better flame retardant effect.

[0037] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0038] The present invention provides a method for preparing an organic silicon flame retardant composite material by using nano hexagonal flaky magnesium hydroxide and black phosphorene through the principle of electrostatic self-assembly. The synthesis process of magnesium hydroxide is controlled by adjusting the concentration of the precipitant, the ultrasonic intensity, the ultrasonic time and other factors to prepare a nano-magnesium hydroxide flame retardant; black phosphorene is prepared by different solvents, stripping times, and ultrasonic intensities of stripping; two flame retardants are compounded in different proportions; and flame retardant composite materials are prepared by different times, proportions, and temperatures of the solidified matrix. If all the conditions for preparing nano-magnesium hydroxide are not within the above-mentioned limited range, nano-hexagonal flaky magnesium hydroxide cannot be obtained; if the time for preparing black phosphorene by the liquid phase stripping method is not within the above-mentioned limited range, black phosphorene cannot be prepared, the stripping time is long, the energy consumption is high, and black phosphorus is easily oxidized; if the time for preparing the mixed composite flame retardant is not within the above-mentioned limited range, the obtained composite flame retardant cannot play various advantages.

[0039] (1) The preparation method is simple, efficient, green and environmentally friendly;

[0040] (2) Nano-magnesium hydroxide and black phosphorene have a synergistic effect. Nano-magnesium hydroxide is coated on the surface of black phosphorene, which is easily oxidized, to prevent it from oxidation and improve its smoke suppression effect. The addition of black phosphorene can also prevent a significant decrease in the mechanical properties of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a specific process flow chart of the present invention;

[0042] Figure 2 This is a scanning electron microscope image of the composite flame retardant of Example 1 of the present invention;

[0043] Figure 3 This is a scanning electron microscope image of the compound flame retardant of Example 2 of the present invention;

[0044] Figure 4 This is a scanning electron microscope image of the composite flame retardant of Example 3 of the present invention;

[0045] Figure 5 This is a scanning electron microscope image of the composite flame retardant of Example 4 of the present invention;

[0046] Figure 6 This is a scanning electron microscope image of the composite flame retardant of Example 5 of the present invention;

[0047] Figure 7 This is a scanning electron microscope image of the compound flame retardant of Comparative Example 1 of the present invention;

[0048] Figure 8 This is a scanning electron microscope image of the compound flame retardant of Comparative Example 2 of the present invention;

[0049] Fig. 9 The scanning electron microscope image and particle size distribution diagram of nano-magnesium hydroxide of Example 1 of the present invention are shown;

[0050] Fig.10 The atomic force microscope image (a) and thickness map (b) of black phosphorene in Example 1 of the present invention;

[0051] Fig.11 is the Raman data of Example 1;

[0052] Fig.12 Thermogravimetric-infrared data of Example 1. DETAILED DESCRIPTION

[0053] The present invention is further described in detail below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto. For process parameters not particularly noted, conventional techniques may be used.

[0054] The ultrasonic enhanced continuous flow equipment of the present invention has been disclosed in CN116603470A.

[0055] The power of ultrasound in the embodiment is 100w.

[0056] Example 1

[0057] This embodiment provides a method for preparing a composite flame retardant and an organosilicon composite flame retardant material. The specific process is as follows: Figure 1 As shown, the following steps are included:

[0058] (1) preparing 1.0 mol / L magnesium chloride hexahydrate and 2.0 mol / L sodium hydroxide aqueous solution and preheating the two reaction solutions to 60° C. at the same time, continuously conveying the magnesium chloride aqueous solution and the sodium hydroxide aqueous solution respectively through an ultrasonic enhanced continuous flow device, adjusting the liquid conveying amount to a flow rate of 150 ml / min, and the pressure gauge to 0.3 MPa, mixing at the end of the liquid inlet pipeline and entering the core reactor, the ultrasonic power of the core reactor is 100 w, and magnesium hydroxide slurry is obtained, and ultrasonic dispersion treatment is performed with an ultrasonic intensity of 50% and an ultrasonic time of 3 h, and then vacuum negative pressure drying is performed to obtain a dry powder at a temperature of 80° C., a pressure of -1.0 MPa, and a time of 6 h to obtain nanoscale hexa-flaky magnesium hydroxide;

[0059] (2) using a liquid phase exfoliation method, using isopropyl alcohol as a solvent, liquid phase exfoliation of black phosphorus for 12 h, and an ultrasonic power of 50% to prepare micron-sized black phosphorus ene, and filtering and drying to obtain black phosphorus ene powder;

[0060] (3) adding a mixture of the product of step (1) (added in an amount of 4.0 wt% of the matrix) and the product of step (2) (added in an amount of 1.0 wt%) to an isopropanol solvent, ultrasonically mixing for 10 min, and performing an electrostatic self-assembly treatment at an ultrasonic intensity of 80% to obtain a composite flame retardant;

[0061] (4) Add the compound flame retardant of step (3) to a matrix of amino polydimethylsiloxane (PDMS) and E-51 epoxy resin in a ratio of 1:1, the curing time is 4 hours, the curing temperature is 50°C, and the amount of the compound flame retardant added is 5.0wt%, to obtain a silicone composite flame retardant material.

[0062] Example 2

[0063] This embodiment provides a method for preparing a composite flame retardant and an organosilicon composite flame retardant material, comprising the following steps:

[0064] (1) preparing 1.0 mol / L magnesium chloride hexahydrate and 2.0 mol / L sodium hydroxide aqueous solution and preheating the two reaction solutions to 60° C. at the same time, continuously conveying the magnesium chloride aqueous solution and the sodium hydroxide aqueous solution respectively through an ultrasonic enhanced continuous flow device, adjusting the liquid conveying amount to a flow rate of 150 ml / min, and the pressure gauge to 0.3 MPa, mixing at the end of the liquid inlet pipeline and entering the core reactor, the ultrasonic power of the core reactor is 100 w, obtaining magnesium hydroxide slurry, and performing ultrasonic dispersion treatment with an ultrasonic intensity of 50% and an ultrasonic time of 3 h to obtain nanoscale hexa-flaky magnesium hydroxide;

[0065] (2) using a liquid phase exfoliation method, using isopropyl alcohol as a solvent, liquid phase exfoliation of black phosphorus for 24 h, and an ultrasonic power of 50% to prepare micron-sized black phosphorus ene, and filtering and drying to obtain black phosphorus ene powder;

[0066] (3) adding a mixture of the product of step (1) (added in an amount of 4.0 wt% of the matrix) and the product of step (2) (added in an amount of 1.0 wt%) to an isopropanol solvent, ultrasonically mixing for 10 min, and performing an electrostatic self-assembly treatment at an ultrasonic intensity of 80% to obtain a composite flame retardant;

[0067] (4) Add the compound flame retardant of step (3) to a matrix of amino polydimethylsiloxane (PDMS) and E-51 epoxy resin in a ratio of 1:1, the curing time is 4 hours, the curing temperature is 50°C, and the amount of the compound flame retardant added is 5.0wt%, to obtain a silicone composite flame retardant material.

[0068] Example 3

[0069] This embodiment provides a method for preparing a composite flame retardant and an organosilicon composite flame retardant material, comprising the following steps:

[0070] (1) preparing 1.0 mol / L magnesium chloride hexahydrate and 2.0 mol / L sodium hydroxide aqueous solution and preheating the two reaction solutions to 60° C. at the same time, continuously conveying the magnesium chloride aqueous solution and the sodium hydroxide aqueous solution respectively through an ultrasonic enhanced continuous flow device, adjusting the liquid conveying amount to a flow rate of 150 ml / min, and the pressure gauge to 0.3 MPa, mixing at the end of the liquid inlet pipeline and entering the core reactor, the ultrasonic power of the core reactor is 100 w, obtaining magnesium hydroxide slurry, and performing ultrasonic dispersion treatment with an ultrasonic intensity of 50% and an ultrasonic time of 3 h, and then vacuum negative pressure drying to obtain dry powder, thereby obtaining nanoscale hexa-flaky magnesium hydroxide;

[0071] (2) using a liquid phase exfoliation method, using isopropyl alcohol as a solvent, liquid phase exfoliation of black phosphorus for 12 h, and ultrasonic power of 80% to prepare micron-sized black phosphorus ene, and filtering and drying to obtain black phosphorus ene powder;

[0072] (3) adding a mixture of the product of step (1) (added in an amount of 4.0 wt% of the matrix) and the product of step (2) (added in an amount of 1.0 wt%) to an isopropanol solvent, ultrasonically mixing for 10 min, and performing an electrostatic self-assembly treatment at an ultrasonic intensity of 80% to obtain a composite flame retardant;

[0073] (4) Add the compound flame retardant of step (3) to a matrix of amino polydimethylsiloxane (PDMS) and E-51 epoxy resin in a ratio of 1:1, the curing time is 4 hours, the curing temperature is 50°C, and the amount of the compound flame retardant added is 5.0wt%, to obtain a silicone composite flame retardant material.

[0074] Example 4

[0075] This embodiment provides a method for preparing a composite flame retardant and an organosilicon composite flame retardant material, comprising the following steps:

[0076] (1) preparing 1.0 mol / L magnesium chloride hexahydrate and 2.0 mol / L sodium hydroxide aqueous solution and preheating the two reaction solutions to 60° C. at the same time, continuously conveying the magnesium chloride aqueous solution and the sodium hydroxide aqueous solution respectively through an ultrasonic enhanced continuous flow device, adjusting the liquid conveying amount to a flow rate of 150 ml / min, and the pressure gauge to 0.3 MPa, mixing at the end of the liquid inlet pipeline and entering the core reactor, the ultrasonic power of the core reactor is 100 w, obtaining magnesium hydroxide slurry, and performing ultrasonic dispersion treatment with an ultrasonic intensity of 50% and an ultrasonic time of 3 h, and then vacuum negative pressure drying to obtain dry powder, thereby obtaining nanoscale hexa-flaky magnesium hydroxide;

[0077] (2) using a liquid phase exfoliation method, using isopropyl alcohol as a solvent, liquid phase exfoliation of black phosphorus for 12 h, and an ultrasonic power of 50% to prepare micron-sized black phosphorus ene, and filtering and drying to obtain black phosphorus ene powder;

[0078] (3) adding the product of step (1) (addition amount is 4.0wt% of the matrix) and the product of step (2) (addition amount is 1.0wt%) to an isopropanol solvent, ultrasonically mixing for 30 minutes, and performing an electrostatic self-assembly treatment with an ultrasonic intensity of 80% to obtain a composite flame retardant by the principle of electrostatic self-assembly;

[0079] (4) Add the compound flame retardant of step (3) to a matrix of amino polydimethylsiloxane (PDMS) and E-51 epoxy resin in a ratio of 1:1, the curing time is 4 hours, the curing temperature is 50°C, and the amount of the compound flame retardant added is 5.0wt%, to obtain a silicone composite flame retardant material.

[0080] Example 5

[0081] This embodiment provides a method for preparing a composite flame retardant and an organosilicon composite flame retardant material, comprising the following steps:

[0082] (1) preparing 1.0 mol / L magnesium chloride hexahydrate and 2.0 mol / L sodium hydroxide aqueous solution and preheating the two reaction solutions to 60° C. at the same time, continuously conveying the magnesium chloride aqueous solution and the sodium hydroxide aqueous solution respectively through an ultrasonic enhanced continuous flow device, adjusting the liquid conveying amount to a flow rate of 150 ml / min, and the pressure gauge to 0.3 MPa, mixing at the end of the liquid inlet pipeline and entering the core reactor, the ultrasonic power of the core reactor is 100 w, obtaining magnesium hydroxide slurry, and performing ultrasonic dispersion treatment with an ultrasonic intensity of 50% and an ultrasonic time of 3 h, and then vacuum negative pressure drying to obtain dry powder, thereby obtaining nanoscale hexa-flaky magnesium hydroxide;

[0083] (2) using a liquid phase exfoliation method, using isopropyl alcohol as a solvent, liquid phase exfoliation of black phosphorus for 12 h, and an ultrasonic power of 50% to prepare micron-sized black phosphorus ene, and filtering and drying to obtain black phosphorus ene powder;

[0084] (3) adding the product of step (1) (added in an amount of 3.0 wt% of the matrix) and the product of step (2) (added in an amount of 2.0 wt%) to an isopropanol solvent, ultrasonically mixing for 10 min, and performing an electrostatic self-assembly treatment at an ultrasonic intensity of 80% to obtain a composite flame retardant;

[0085] (4) Add the compound flame retardant of step (3) to a matrix of amino polydimethylsiloxane (PDMS) and E-51 epoxy resin in a ratio of 1:1, the curing time is 4 hours, the curing temperature is 50°C, and the amount of the compound flame retardant added is 5.0wt%, to obtain a silicone composite flame retardant material.

[0086] Comparative Example 1

[0087] (1) preparing 1.0 mol / L magnesium chloride hexahydrate and 2.0 mol / L sodium hydroxide aqueous solution and preheating the two reaction solutions to 60° C. at the same time, continuously delivering the magnesium chloride aqueous solution and the sodium hydroxide aqueous solution respectively through an ultrasonic enhanced continuous flow device, adjusting the liquid delivery rate to 150 ml / min, the pressure gauge to 0.2-0.3 MPa, mixing at the end of the liquid inlet pipeline and entering the core reactor, the ultrasonic power of the core reactor is 100 w, and obtaining magnesium hydroxide slurry, without ultrasonic dispersion treatment, static aging for 3 hours, vacuum negative pressure drying to obtain dry powder, and obtaining magnesium hydroxide;

[0088] (2) using a liquid phase exfoliation method, using isopropyl alcohol as a solvent, liquid phase exfoliation of black phosphorus for 12 h, and an ultrasonic power of 50% to prepare micron-sized black phosphorus ene, and filtering and drying to obtain black phosphorus ene powder;

[0089] (3) adding the product of step (1) (added in an amount of 1.0 wt%) and the product of step (2) (added in an amount of 1.0 wt%) to an isopropanol solvent, mixing for 10 min, and subjecting the mixture to an electrostatic self-assembly treatment at an ultrasonic intensity of 80% to obtain a composite flame retardant;

[0090] (4) Add the compound flame retardant described in step (3) to a matrix of amino polydimethylsiloxane (PDMS) and E-51 epoxy resin in a ratio of 1:1, the curing time is 4 hours, the curing temperature is 50°C, and the amount of the compound flame retardant added is 2.0wt%, to obtain a silicone composite flame retardant material.

[0091] Comparative Example 2

[0092] (1) preparing 1.0 mol / L magnesium chloride hexahydrate and 2.0 mol / L sodium hydroxide aqueous solution and preheating the two reaction solutions to 60° C. at the same time, continuously conveying the magnesium chloride aqueous solution and the sodium hydroxide aqueous solution respectively through an ultrasonic enhanced continuous flow device, adjusting the liquid conveying amount to a flow rate of 150 ml / min, and the pressure gauge to 0.3 MPa, mixing at the end of the liquid inlet pipeline and entering the core reactor, the ultrasonic power of the core reactor is 100 w, obtaining magnesium hydroxide slurry, and performing ultrasonic dispersion treatment with an ultrasonic intensity of 50% and an ultrasonic time of 3 h, and vacuum negative pressure drying to obtain dry powder to obtain nano magnesium hydroxide;

[0093] (2) using a liquid phase exfoliation method, using isopropanol as a solvent, liquid phase exfoliation of black phosphorus for 1 h, and an ultrasonic power of 50% to prepare micron-sized black phosphorus ene, and filtering and drying to obtain black phosphorus ene powder;

[0094] (3) adding the product of step (1) (addition amount is 4.0wt% of the matrix) and the product of step (2) (addition amount is 0.5wt%) to an isopropanol solvent, mixing for 10 minutes and performing an electrostatic self-assembly treatment with an ultrasonic intensity of 80% to obtain a composite flame retardant by the principle of electrostatic self-assembly;

[0095] (4) Add the compound flame retardant of step (3) to a matrix of amino polydimethylsiloxane (PDMS) and epoxy E-51 in a ratio of 1:1, the curing time is 4 hours, the curing temperature is 50°C, and the amount of the compound flame retardant added is 4.5wt%, to obtain a silicone composite flame retardant material.

[0096] Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 It can be seen from the scanning electron microscope image with a magnification of 50,000 times that magnesium hydroxide is wrapped on the surface of black phosphorene in the form of regular hexagonal flakes, and the dispersion of magnesium hydroxide on the surface of black phosphorene is good. The size of the obtained composite flame retardant is 5 to 6 microns.

[0097] Figure 7 This is a scanning electron microscope image of the compound flame retardant in comparative example 1. It can be seen from the scanning electron microscope image at a magnification of 50,000 times that due to the low amount of magnesium hydroxide added, black phosphorene cannot be well coated and the morphology of the flame retardant is poor.

[0098] Figure 8 This is a scanning electron microscope image of the compound flame retardant in comparative example 2. It can be seen from the scanning electron microscope image at a magnification of 50,000 times that due to the low addition amount of black phosphorus ene, there is an excess of magnesium hydroxide, poor dispersibility, and the flame retardant is easy to agglomerate.

[0099] Fig. 9 This is a scanning electron microscope image of nano-magnesium hydroxide. The magnesium hydroxide has a small particle size (300-500nm), a narrow particle size distribution (PDI is 0.393), a controllable morphology, and is in the form of regular nano-hexagonal flakes.

[0100] Fig.10 It can be seen that the thickness of black phosphorene is 1.0468nm, and the thickness of a layer of black phosphorene is 0.53nm, which is about 2 layers thick.

[0101] Comparative Example 3

[0102] Different from Example 1, when only 5 wt % of nano magnesium hydroxide is added, the vertical combustion grade V-0 cannot be achieved.

[0103] Test Example 1

[0104] UL94 vertical burning grade standard: Use vertical burning tester (CZF-3) to test the vertical burning (UL-94) burning grade of PDMS and its composite materials. The sample size is 127*10*3mm. The test method of PDMS refers to the standard ASTMD3801.

[0105] Limiting oxygen index (%): The limiting oxygen index (LOI) of PDMS and its composites was tested using an oxygen index tester (JF-3), and the sample size was 120*6*3mm 3 , the test method refers to standard ASTM D2863-2009.

[0106] Thermal conductivity (W·m -1 ·K -1 ): Laser flash analysis (LFA 467, NETZSCH, standard: ASTM E1461) was used to determine the thermal conductivity of the composite material.

[0107] Table 1 shows the vertical combustion, limiting oxygen index and thermal conductivity data of the composite materials of Examples 1-5 and Comparative Examples 1-2 of the present invention.

[0108] Table 1

[0109] Vertical combustion Limiting oxygen index (%) <![CDATA[Thermal conductivity (W·m -1 ·K -1 ) <!-- 6 -->]]> Example 1 V-0 25.7 1.74 Example 2 V-0 25.4 1.71 Example 3 V-0 25.4 1.73 Example 4 V-0 25.3 1.61 Example 5 V-0 25.9 1.69 Comparative Example 1 V-1 24.1 0.89 Comparative Example 2 V-1 23.3 1.55 PDMS NR 20.1 0.38

[0110] Table 2 shows the cone calorimetry data of Examples 1-5 of the present invention.

[0111] Table 2

[0112] <![CDATA[PHRR(kW / m 2 )]]> <![CDATA[THR(MJ / m 2 )]]> <![CDATA[TSP(m 2 )]]> CO(g / s) <![CDATA[CO2P(g / s)]]> Example 1 530.66 109.87 17.89 0.01788 0.2096 Example 2 528.41 108.76 17.34 0.01736 0.1985 Example 3 527.33 108.28 17.05 0.01701 0.1910 Example 4 526.97 107.19 16.49 0.01687 0.1879 Example 5 513.99 101.21 14.62 0.01371 0.1664 PDMS 760.15 124.35 23.34 0.02693 0.2728

[0113] Some analysis is made on Table 1 and Table 2. It can be seen from Table 1 that Examples 1-5 can all reach the vertical combustion level V-0, and the materials can all self-extinguish within 10 seconds, the combustion materials do not drip, and the cotton wool is not ignited. However, Comparative Examples 1-2 can only reach the vertical combustion level V-1, and the materials can self-extinguish within 30 seconds without dripping combustion materials, and the cotton wool is not ignited; adding a sufficient amount of nano magnesium hydroxide, the thermal conductivity of the material will be relatively improved. It can be seen from Table 2 that the higher the PHRR (peak heat release rate) value, the greater the danger of the fire, and the addition of compound flame retardants can effectively improve the flame retardant properties of silicone materials; THR (total heat release) reflects the flammability of the material and the total energy it can provide in a fire, and the addition of compound flame retardants can effectively reduce the flammability of silicone materials; the reduction in TSP (total smoke generation), CO, and CO2 release indicates that the addition of compound flame retardants has a smoke suppression effect.

[0114] Raman data show that the smaller the ratio of D peak to G peak (I D / I G), the denser the residual carbon, the more synergistic the two can be (the residual carbon of PDMS after combustion I D / I G =2.25, add 1.0BP@4.0MH PDMS combustion residual carbon I D / I G Thermogravimetric-infrared data showed that the residual carbon after combustion of PDMS with 1.0BP@4.0MH was 2190cm -1 There is no obvious infrared peak of CO at the site, indicating that the magnesium oxide generated after the combustion of magnesium hydroxide has adsorptive properties and can absorb gases such as CO (BP has no adsorption effect), indicating that the two have a synergistic effect.

[0115] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A nano magnesium hydroxide / black phosphorene composite flame retardant, characterized in that: The invention comprises nano magnesium hydroxide and black phosphorene, wherein the mass ratio of the nano magnesium hydroxide to the black phosphorene is 1 to 10:

1.

2. The nano magnesium hydroxide / black phosphorene composite flame retardant according to claim 1, characterized in that: The preparation method of the nano magnesium hydroxide is as follows: (1) preparing a soluble magnesium salt solution and a precipitant aqueous solution respectively, preheating them respectively, continuously conveying the soluble magnesium salt solution and the precipitant aqueous solution respectively, and performing ultrasonic and mixing reactions to obtain a magnesium hydroxide nano-slurry; (2) Ultrasonic dispersion of the magnesium hydroxide nano-slurry is performed, filtration is performed, and drying is performed to obtain nano magnesium hydroxide.

3. The nano magnesium hydroxide / black phosphorene composite flame retardant according to claim 2, characterized in that: In step (1), the delivery flow rate of the soluble magnesium salt solution and the precipitant aqueous solution is equal, which is 150-180 mL / min, the delivery pressure is 0.2-0.3 MPa, and the power of the ultrasound is 100-200 W; The concentration of the soluble magnesium salt solution is 1.0 mol / L-3.0 mol / L, and the ratio of the concentration of the soluble magnesium salt solution to the concentration of the precipitant aqueous solution is 1:2-3; The ultrasonic power in step (2) is 50-100w, and the ultrasonic time is 1-3h; The soluble magnesium salt is magnesium chloride, magnesium sulfate or magnesium nitrate, and the precipitant is sodium hydroxide or potassium hydroxide.

4. The nano magnesium hydroxide / black phosphorene composite flame retardant according to claim 1, characterized in that: The black phosphorene is prepared by a liquid phase exfoliation method, and the specific steps are as follows: Black phosphorus is placed in a solvent, ultrasonicated, filtered and dried to obtain black phosphorene.

5. The nano magnesium hydroxide / black phosphorene composite flame retardant according to claim 4, characterized in that: The solvent is one of isopropanol, N-methylpyrrolidone and anhydrous ethanol; The ultrasonic power is 50-80w, and the ultrasonic time is 12-24h.

6. The method for preparing the nano magnesium hydroxide / black phosphorene composite flame retardant according to claim 1, characterized in that: The steps include: Adding nano magnesium hydroxide and black phosphorene into a solvent, mixing, ultrasonicating, and performing electrostatic self-assembly to obtain a nano magnesium hydroxide / black phosphorene composite flame retardant; The solvent is one of isopropanol, acetone and toluene, and the mixing time is 5-30 minutes; The power of the ultrasound is 20-80w.

7. Use of the nano magnesium hydroxide / black phosphorene composite flame retardant according to any one of claims 1 to 5 in the preparation of flame retardant materials.

8. The use according to claim 7, characterized in that: The application comprises the following steps: Adding nano magnesium hydroxide / black phosphorene composite flame retardant to the base resin and curing to obtain a flame retardant material; The addition amount of the nano magnesium hydroxide / black phosphorene composite flame retardant is 1-10wt% of the base resin.

9. The use according to claim 8, characterized in that: The curing temperature is 30°C-100°C, and the curing time is 3h-12h; The matrix resin includes aminopolydimethylsiloxane and epoxy resin in a mass ratio of 1-10:

1.

10. An organic silicon composite flame retardant material, characterized in that: The invention is prepared by the application described in any one of claims 7 to 9.

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