Wet modified magnesium hydroxide flame retardant and preparation method thereof

Abstract

The invention relates to the field of flame retardants, in particular to a wet modified magnesium hydroxide flame retardant and a preparation method thereof. The preparation method comprises the following steps: step 1, preparing aminated magnesium hydroxide particles; step 2, preparing amino sulfonamide magnesium hydroxide particles; and step 3, preparing the modified magnesium hydroxide flame retardant. Compared with a traditional magnesium hydroxide flame retardant, the use amount of the composite flame retardant in a flame-retardant material can be reduced by 10%, but even if the use amount is reduced, the composite flame retardant still can show good flame retardance, and the mechanical property and the heat and humidity resistance of a resin material can be obviously improved.

Description

Technical Field

[0001] The invention relates to the field of flame retardants, and in particular to a wet-process modified magnesium hydroxide flame retardant and a preparation method thereof. Background Art

[0002] With the rapid development of the plastics industry, wires and cables, printed circuit boards, automobiles, aerospace, textiles and clothing, decorative fabrics, etc., the demand for flame retardants, especially non-toxic and smoke-suppressing flame retardants, will be more urgent. Since inorganic flame retardants have low toxicity, they are fully in line with the current trend of flame retardants developing towards environmentally friendly ones. However, since inorganic flame retardants (such as aluminum hydroxide, magnesium hydroxide, zinc borate, etc.) are filler-type, they are added in large amounts to the resin, which often affects the processing properties and mechanical properties of the material to varying degrees. Therefore, the modification of traditional inorganic flame retardants has become a hot research topic.

[0003] As an inorganic flame retardant that is widely used on the market, magnesium hydroxide can effectively reduce the flammability of polymers, has a large heat capacity, can delay the decomposition of the matrix, absorb heat during decomposition, dilute oxygen, and the decomposed products can isolate the air and inhibit further combustion. Compared with other inorganic flame retardants, magnesium hydroxide can not only make polymer materials obtain excellent flame retardant effects, but also inhibit the generation of toxic gases such as smoke and hydrogen halides, giving the materials non-toxic and non-corrosive characteristics. However, magnesium hydroxide also has the following disadvantages: First, the amount used as a flame retardant is too high, which has a great impact on the mechanical properties and processing properties of the material; among them, ordinary magnesium hydroxide is mostly hexagonal or amorphous crystals, with a large specific surface area, strong agglomeration between grains, and poor dispersion in resin.

[0004] Wet modification can improve the dispersibility and compatibility of magnesium hydroxide with materials, and improve the performance of magnesium hydroxide and resin. However, in the current wet modification research on magnesium hydroxide, a dispersant is used to modify magnesium hydroxide nanopowder. Although the compatibility of the modified magnesium hydroxide in the resin is improved, the amount used as a flame retardant is still too high, and the overall performance improvement of the resin is very limited. Therefore, it is an urgent problem for those skilled in the art to find a modified magnesium hydroxide flame retardant with good flame retardant effect and capable of improving the performance of resin materials. Summary of the invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide a wet-process modified magnesium hydroxide flame retardant and a preparation method thereof.

[0006] The purpose of the present invention is achieved by adopting the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a wet modified magnesium hydroxide flame retardant, comprising the following steps:

[0008] Step 1, preparing aminated magnesium hydroxide particles:

[0009] Weigh magnesium hydroxide particles and deionized water to obtain a magnesium hydroxide particle mixed solution; add an aminosilane coupling agent to the mixed solution of ethanol and deionized water, and reflux to obtain an aminosilane mixed solution; place the magnesium hydroxide particle mixed solution at a temperature of 50-60° C. and stir, then add the aminosilane mixed solution dropwise thereto, and after the dropwise addition is completed, continue to keep warm and stir for 2-6 hours, filter, wash and dry to obtain aminated magnesium hydroxide particles;

[0010] Step 2, preparing aminosulfonamidated magnesium hydroxide particles:

[0011] Adding the aminated magnesium hydroxide particles into the first organic solvent, and then dropping a small amount of triethylamine, ultrasonically mixing, and then placing in an ice water bath, introducing nitrogen as a protective gas, and dropping the aminosulfonyl chloride solution while stirring, and after the dropwise addition is completed, heating to room temperature, keeping the temperature and stirring for 2-8 hours, after the reaction is completed, filtering, washing and drying to obtain the aminosulfonamidated magnesium hydroxide particles;

[0012] Step 3, preparing modified magnesium hydroxide flame retardant:

[0013] Add the formaldehyde benzoxazine into the second organic solvent, and after it is fully dissolved, add aminosulfonamidated magnesium hydroxide particles under the protection of nitrogen, continue stirring until uniform, add the catalyst, raise the temperature to 45-95°C, keep stirring for 3-10 hours, after the reaction is completed, remove the solvent under reduced pressure, wash with alcohol for at least three times, and then vacuum dry to obtain a modified magnesium hydroxide flame retardant.

[0014] Preferably, in step 1, the particle size of the magnesium hydroxide particles is 0.5-50 μm.

[0015] Preferably, in the magnesium hydroxide particle mixed solution of step 1, the mass volume ratio of magnesium hydroxide particles to deionized water is 1 g: (10-50) mL.

[0016] Preferably, in the aminosilane mixed liquid of step 1, the aminosilane coupling agent is γ-aminopropyltriethoxysilane (A-1100) or γ-aminopropyltrimethoxysilane (A-1110); the mass volume ratio of the aminosilane coupling agent, ethanol and deionized water is (1.2-5.6) g: (70-90) mL: (10-30) mL.

[0017] Preferably, in step 1, the volume ratio of the magnesium hydroxide particle mixed liquid to the aminosilane mixed liquid is 1:0.1-0.5.

[0018] Preferably, in step 2, the first organic solvent is one of acetonitrile, tetrahydrofuran, dichloromethane, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0019] Preferably, in step 2, the amount of triethylamine added is 10%-30% of the mass of aminosulfonyl chloride.

[0020] Preferably, in step 2, the aminosulfonyl chloride solution is prepared by mixing aminosulfonyl chloride and acetonitrile in a mass volume ratio of (1.1-2.2) g:(5-15) mL.

[0021] Preferably, in step 2, the mass volume ratio of the amination magnesium hydroxide particles, the aminosulfonyl chloride solution and the first organic solvent is 1 g: (3.2-6.4) mL: (15-35) mL.

[0022] Preferably, in step 3, the second organic solvent is one of xylene, tetrahydrofuran, ethyl acetate, 1,4-dioxane, chloroform, N,N-dimethylformamide and N,N-dimethylacetamide.

[0023] Preferably, in step 3, the mass volume ratio of aminosulfonamidated magnesium hydroxide particles, formaldehyded benzoxazine and the second organic solvent is 1 g:(1.7-3.4) g:(20-60) mL.

[0024] Preferably, in step 3, the method for preparing the aldehyde-formylated benzoxazine comprises:

[0025] Weigh bisphenol A, 4-aminobutyraldehyde and aniline, mix them in 1,4-dioxane, stir them thoroughly, add 37wt% formaldehyde solution, heat to 70-90°C, keep stirring for 3-8h, remove the solvent under reduced pressure, dissolve in ether again, add sodium hydroxide solution dropwise until pH=7, wash with water for at least three times, and dry under reduced pressure to obtain formaldehyde benzoxazine;

[0026] Among them, the mass volume ratio of bisphenol A, 4-aminobutyraldehyde, aniline, formaldehyde solution and 1,4-dioxane is (2.3-4.6) g: (0.7-1.7) g: (0.8-1.6) g: (2.4-7.2) g: (20-60) mL.

[0027] In a second aspect, the present invention provides a wet-process modified magnesium hydroxide flame retardant prepared by the above-mentioned preparation method.

[0028] In a third aspect, the present invention provides an application of a wet-process modified magnesium hydroxide flame retardant in rubber or plastic.

[0029] The beneficial effects of the present invention are:

[0030] 1. The present invention prepares a novel magnesium hydroxide flame retardant, which is prepared by a wet treatment method, and the modified magnesium hydroxide flame retardant finally obtained is an organic-inorganic coated composite flame retardant. Compared with the traditional magnesium hydroxide flame retardant, the amount of the composite flame retardant in the flame retardant material can be reduced by 10%, but even if the amount is reduced, it can still show good flame retardancy, and can also have a more obvious improvement on the mechanical properties and moisture and heat resistance of the resin material.

[0031] 2. The modified magnesium hydroxide flame retardant of the present invention is made on the basis of magnesium hydroxide particles. Specifically, the magnesium hydroxide particles are first surface-modified with aminosilane. In this process, the silanol groups released by the hydrolysis of the aminosilane coupling agent combine with the hydroxyl groups on the surface of the magnesium hydroxide to obtain amination magnesium hydroxide particles; then react with aminosulfonyl chloride, and the sulfonyl chloride group in the aminosulfonyl chloride structure combines with the amino group on the surface of the amination magnesium hydroxide particles to obtain aminosulfonamidated magnesium hydroxide particles; finally, an amino-aldehyde condensation reaction occurs with the aldehyde-formyl benzoxazine to finally obtain the modified magnesium hydroxide flame retardant.

[0032] 3. The organic structure coated on the surface of the modified magnesium hydroxide flame retardant prepared by the present invention includes a large number of sulfonamide groups, Schiff base groups and benzoxazine groups, which give the flame retardant better compatibility with the resin material, while improving its flame retardancy and moisture and heat resistance. In addition, it has the characteristics of non-toxicity, halogen-free, smoke suppression and high temperature resistance, and is a green and environmentally friendly composite flame retardant. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention is further described using the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative work.

[0034] Figure 1 This is a SEM schematic diagram of the modified magnesium hydroxide flame retardant prepared by the wet method in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. The change or adjustment of the relative relationship thereof shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0036] In order to better understand the above technical scheme, the exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0037] The present invention will be further described below in conjunction with the following examples.

[0038] Example 1

[0039] A wet modified magnesium hydroxide flame retardant, the preparation method comprising the following steps:

[0040] Step 1, preparing aminated magnesium hydroxide particles:

[0041] Weigh magnesium hydroxide particles with a particle size of 15-20 μm and mix them with deionized water, the mass volume ratio of the magnesium hydroxide particles to the deionized water is 1 g:30 mL, and mix them evenly after ultrasonic treatment to obtain a magnesium hydroxide particle mixed solution;

[0042] Mix ethanol and deionized water, add γ-aminopropyltriethoxysilane (A-1100) thereto, the mass volume ratio of γ-aminopropyltriethoxysilane (A-1100), ethanol and deionized water is 3.5g:80mL:20mL, then heat to 80°C, keep reflux for 0.5h, and obtain an aminosilane mixed liquid;

[0043] The magnesium hydroxide particle mixture is placed at a temperature of 55° C. and stirred, and then the aminosilane mixture is added dropwise thereto, the volume ratio of the magnesium hydroxide particle mixture to the aminosilane mixture is 1:0.3, and the dropping speed is 5 mL / min. After the dropwise addition is completed, the mixture is kept warm and stirred for 4 hours, and then the solid is collected by suction filtration, washed with water at least three times, and then vacuum dried to obtain aminated magnesium hydroxide particles;

[0044] Step 2, preparing aminosulfonamidated magnesium hydroxide particles:

[0045] First, aminosulfonyl chloride and acetonitrile are prepared into an aminosulfonyl chloride solution in a mass volume ratio of 1.6 g:10 mL; then, the aminated magnesium hydroxide particles are added into the acetonitrile, and then triethylamine in an amount of 20% by mass of the aminosulfonyl chloride is added dropwise, and the mixture is ultrasonically mixed evenly, and then the mixture is placed in an ice water bath, and nitrogen is introduced as a protective gas, and the aminosulfonyl chloride solution is added dropwise while stirring, wherein the mass volume ratio of the aminated magnesium hydroxide particles, the aminosulfonyl chloride solution and the acetonitrile is 1 g:4.8 mL:25 mL. After the addition is completed, the mixture is heated to room temperature, and the mixture is stirred for 5 hours at this temperature. After the reaction is completed, the solid is collected by suction filtration, washed with alcohol for at least three times, and dried in vacuo to obtain aminosulfonamidated magnesium hydroxide particles;

[0046] Step 3, preparation of aldehyde-substituted benzoxazine:

[0047] Weigh bisphenol A, 4-aminobutyraldehyde and aniline, mix them in 1,4-dioxane, stir them thoroughly, add 37wt% formaldehyde solution, the mass volume ratio of bisphenol A, 4-aminobutyraldehyde, aniline, formaldehyde solution and 1,4-dioxane is 3.4g:1.2g:1.2g:3.6g:30mL, heat to 80°C, keep stirring for 5h, remove the solvent under reduced pressure, dissolve in ether again, add 0.05mol / L sodium hydroxide solution dropwise to pH=7, wash with water for at least three times, and dry under reduced pressure to obtain formaldehyde benzoxazine;

[0048] Step 4, preparing modified magnesium hydroxide flame retardant:

[0049] Add the formaldehyde benzoxazine into xylene and after it is fully dissolved, add aminosulfonamidated magnesium hydroxide particles under the protection of nitrogen. The mass volume ratio of aminosulfonamidated magnesium hydroxide particles, formaldehyde benzoxazine and xylene is 1g:2.6g:40mL. After continuous stirring until uniform, add the catalyst, raise the temperature to 80°C, and stir for 8 hours. After the reaction is completed, remove the solvent under reduced pressure, wash with alcohol at least three times, and then dry in vacuum to obtain a modified magnesium hydroxide flame retardant.

[0050] Example 2

[0051] A wet modified magnesium hydroxide flame retardant, the preparation method comprising the following steps:

[0052] Step 1, preparing ammoniated magnesium hydroxide particles:

[0053] Weigh magnesium hydroxide particles with a particle size of 5-10 μm and mix them with deionized water, the mass volume ratio of the magnesium hydroxide particles to the deionized water is 1 g:10 mL, and mix them evenly after ultrasonic treatment to obtain a magnesium hydroxide particle mixed solution;

[0054] A certain amount of ethanol and deionized water were mixed, and γ-aminopropyltrimethoxysilane (A-1110) was added thereto, the mass volume ratio of γ-aminopropyltrimethoxysilane, ethanol and deionized water was 1.2 g:70 mL:10 mL, and then the temperature was raised to 70°C, and the mixture was kept at reflux for 0.2 h to obtain an aminosilane mixed solution;

[0055] The magnesium hydroxide particle mixture is placed at a temperature of 50° C. and stirred, and then the aminosilane mixture is added dropwise thereto, the volume ratio of the magnesium hydroxide particle mixture to the aminosilane mixture is 1:0.1, and the dropping speed is 3 mL / min. After the dropwise addition is completed, the mixture is kept warm and stirred for 2 hours, and then the solid is collected by suction filtration, washed with water at least three times, and then vacuum dried to obtain aminated magnesium hydroxide particles;

[0056] Step 2, preparing aminosulfonamidated magnesium hydroxide particles:

[0057] First, aminosulfonyl chloride and acetonitrile are prepared into an aminosulfonyl chloride solution in a mass volume ratio of 1.1 g:5 mL; then, the aminated magnesium hydroxide particles are added into tetrahydrofuran, and a small amount of triethylamine is added dropwise, and the mixture is ultrasonically mixed to be uniform, and then the mixture is placed in an ice water bath, and nitrogen is introduced as a protective gas, and the aminosulfonyl chloride solution is added dropwise while stirring, wherein the mass volume ratio of the aminated magnesium hydroxide particles, the aminosulfonyl chloride solution and the tetrahydrofuran is 1 g:3.2 mL:15 mL. After the addition is completed, the mixture is heated to room temperature, and the mixture is stirred for 2 hours at this temperature. After the reaction is completed, the solid is collected by suction filtration, washed with alcohol for at least three times, and dried in vacuo to obtain aminosulfonamidated magnesium hydroxide particles;

[0058] Step 3, preparation of aldehyde-substituted benzoxazine:

[0059] Weigh bisphenol A, 4-aminobutyraldehyde and aniline, mix them in 1,4-dioxane, stir them thoroughly, add 37wt% formaldehyde solution, the mass volume ratio of bisphenol A, 4-aminobutyraldehyde, aniline, formaldehyde solution and 1,4-dioxane is 2.3g:0.7g:0.8g:2.4g:20mL, heat to 70°C, keep stirring for 3h, remove the solvent under reduced pressure, dissolve in ether again, add sodium hydroxide solution dropwise to pH=7, wash with water for at least three times, and dry under reduced pressure to obtain formaldehyde benzoxazine;

[0060] Step 4, preparing modified magnesium hydroxide flame retardant:

[0061] Add the aldehyde-modified benzoxazine into tetrahydrofuran, and after it is fully dissolved, add aminosulfonamidated magnesium hydroxide particles under the protection of nitrogen, the mass volume ratio of aminosulfonamidated magnesium hydroxide particles, aldehyde-modified benzoxazine and tetrahydrofuran is 1g:1.7g:20mL, continue to stir until uniform, add the catalyst, heat to 45°C, keep stirring for 3h, after the reaction is completed, remove the solvent under reduced pressure, wash with alcohol at least three times, and then dry in vacuum to obtain a modified magnesium hydroxide flame retardant.

[0062] Example 3

[0063] A wet modified magnesium hydroxide flame retardant, the preparation method comprising the following steps:

[0064] Step 1, preparing ammoniated magnesium hydroxide particles:

[0065] Weigh magnesium hydroxide particles with a particle size of 20-30 μm and mix them with deionized water, the mass volume ratio of the magnesium hydroxide particles to the deionized water is 1 g:50 mL, and mix them evenly after ultrasonic treatment to obtain a magnesium hydroxide particle mixed solution;

[0066] A certain amount of ethanol and deionized water were mixed, and γ-aminopropyltriethoxysilane (A-1100) was added thereto, the mass volume ratio of γ-aminopropyltriethoxysilane, ethanol and deionized water was 5.6 g:90 mL:30 mL, and then the temperature was raised to 90° C. and refluxed for 0.7 h to obtain an aminosilane mixed liquid;

[0067] The magnesium hydroxide particle mixture is placed at a temperature of 60° C. and stirred, and then the aminosilane mixture is added dropwise thereto, the volume ratio of the magnesium hydroxide particle mixture to the aminosilane mixture is 1:0.5, and the dropping speed is 8 mL / min. After the dropwise addition is completed, the mixture is kept warm and stirred for 6 hours, and then the solid is collected by suction filtration, washed with water at least three times, and then vacuum dried to obtain aminated magnesium hydroxide particles;

[0068] Step 2, preparing aminosulfonamidated magnesium hydroxide particles:

[0069] First, aminosulfonyl chloride and acetonitrile are prepared into an aminosulfonyl chloride solution in a mass volume ratio of 2.2g:15mL; then, the amidated magnesium hydroxide particles are added into the first organic solvent, and a small amount of triethylamine is added dropwise, and the mixture is ultrasonically mixed evenly, and then the mixture is placed in an ice-water bath, and nitrogen is introduced as a protective gas, and the aminosulfonyl chloride solution is added dropwise while stirring, wherein the mass volume ratio of the amidated magnesium hydroxide particles, the aminosulfonyl chloride solution and the first organic solvent is 1g:6.4mL:35mL. After the addition is completed, the mixture is heated to room temperature, and the mixture is stirred at this temperature for 8h. After the reaction is completed, the solid is collected by suction filtration, washed with alcohol for at least three times, and dried in vacuo to obtain aminosulfonamidated magnesium hydroxide particles;

[0070] Step 3, preparation of aldehyde-substituted benzoxazine:

[0071] Weigh bisphenol A, 4-aminobutyraldehyde and aniline, mix them in 1,4-dioxane, stir them thoroughly, add 37wt% formaldehyde solution, the mass volume ratio of bisphenol A, 4-aminobutyraldehyde, aniline, formaldehyde solution and 1,4-dioxane is 4.6g:1.7g:1.6g:7.2g:60mL, heat to 90°C, keep stirring for 8h, remove the solvent under reduced pressure, dissolve in ether again, add sodium hydroxide solution dropwise to pH=7, wash with water for at least three times, and dry under reduced pressure to obtain formaldehyde benzoxazine;

[0072] Step 4, preparing modified magnesium hydroxide flame retardant:

[0073] Add the aldehyde-modified benzoxazine into 1,4-dioxane, and after it is fully dissolved, add aminosulfonamidated magnesium hydroxide particles under the protection of nitrogen. The mass volume ratio of aminosulfonamidated magnesium hydroxide particles, aldehyde-modified benzoxazine and 1,4-dioxane is 1g:1.7g:60mL. After continuous stirring until uniform, add the catalyst, heat to 95°C, and stir for 10 hours. After the reaction is completed, remove the solvent under reduced pressure, wash with alcohol at least three times, and then dry in vacuum to obtain a modified magnesium hydroxide flame retardant.

[0074] Comparative Example 1

[0075] A wet-process modified magnesium hydroxide flame retardant is different from Example 1 in that only the process of step 1 is retained, that is, the flame retardant finally obtained is amide magnesium hydroxide particles.

[0076] Comparative Example 2

[0077] A wet-process modified magnesium hydroxide flame retardant is different from Example 1 in that only the processes of steps 1 and 2 are retained, that is, the flame retardant finally obtained is aminosulfonamidated magnesium hydroxide particles.

[0078] Comparative Example 3

[0079] A wet-process modified magnesium hydroxide flame retardant, which is different from Example 1 in that the flame retardant finally obtained is a composite of aminated magnesium hydroxide particles and formaldehyde-modified benzoxazine, namely:

[0080] Step 1, preparing aminated magnesium hydroxide particles, the same as in Example 1;

[0081] Step 2, add the formaldehyded benzoxazine into xylene, and after it is fully dissolved, add the amide magnesium hydroxide particles under the protection of nitrogen, the mass volume ratio of the amide magnesium hydroxide particles, the formaldehyded benzoxazine and the xylene is 1g:2.6g:40mL, continue to stir until uniform, add the catalyst, heat to 80°C, keep stirring for 8h, after the reaction is completed, remove the solvent under reduced pressure, wash with alcohol at least three times, and then vacuum dry to obtain a modified magnesium hydroxide flame retardant.

[0082] Experimental example

[0083] In order to more clearly illustrate the content of the present invention, the modified magnesium hydroxide flame retardants prepared in Example 1 and Comparative Examples 1-3 are respectively applied to composite plastic materials, and the specific components are calculated by weight and include the following:

[0084] 50 parts PP resin (density 0.91g / cm 3 )、25 parts PA6 resin (density 1.13g / cm 3 ), 18 parts of POE-g-MAH (grafting rate 1%), 13 parts of modified magnesium hydroxide flame retardant, 4 parts of polyethylene wax and 1 part of antioxidant 1010.

[0085] After the above ingredients are mixed according to the amount, they are extruded into granules in a twin-screw extruder at a temperature range of 215-255° C., a rotation speed of 100 r / min, and an aspect ratio L / D of 38.

[0086] The obtained composite plastic materials were then marked as Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3, respectively, and then the tensile strength (ISO 527-2:2012), notched impact strength (ISO 179-1:2010), vertical burning grade UL94 (ANSI / UL-94-1985) and moisture and heat resistance (120°C, 90RH% treatment for 72h) were tested respectively.

[0087] The test results are shown in Table 1:

[0088] Table 1 Performance test of composite plastic materials with different flame retardants

[0089]

[0090] From the data results in Table 1, it is obtained that on the basis that the flame retardant grade UL-94 of the composite plastic material of Example 1 reaches V-0, the composite plastic material prepared using the flame retardant of Example 1 has higher tensile strength and notched impact strength, indicating that the flame retardant of Example 1 has a good improvement in the mechanical properties of the resin material; in addition, after wet heat treatment, the tensile strength and notched impact strength of the composite plastic material of Example 1 change less, indicating that the flame retardant of Example 1 has a good improvement in the wet heat resistance of the resin material. In summary, the flame retardant prepared in Example 1 not only has good flame retardancy, but also can have a more obvious improvement in the mechanical properties and wet heat resistance of the resin material.

[0091] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a wet modified magnesium hydroxide flame retardant, characterized in that: The following steps are involved: Step 1, preparing aminated magnesium hydroxide particles: Weigh magnesium hydroxide particles and deionized water to obtain a magnesium hydroxide particle mixed solution; add an aminosilane coupling agent into the mixed solution of ethanol and deionized water, and reflux to obtain an aminosilane mixed solution; place the magnesium hydroxide particle mixed solution at a temperature of 50-60° C. and stir, add the aminosilane mixed solution drop by drop, and after the dropwise addition is completed, continue to keep warm and stir for 2-6 hours, filter, wash and dry to obtain aminated magnesium hydroxide particles; Step 2, preparing aminosulfonamidated magnesium hydroxide particles: Adding the aminated magnesium hydroxide particles into the first organic solvent, and then dropping a small amount of triethylamine, ultrasonically mixing, and then placing in an ice water bath, introducing nitrogen as a protective gas, and dropping the aminosulfonyl chloride solution while stirring, and after the dropwise addition is completed, heating to room temperature, keeping the temperature and stirring for 2-8 hours, after the reaction is completed, filtering, washing and drying to obtain the aminosulfonamidated magnesium hydroxide particles; Step 3, preparing modified magnesium hydroxide flame retardant: Add the formaldehyde benzoxazine into the second organic solvent, and after it is fully dissolved, add aminosulfonamidated magnesium hydroxide particles under the protection of nitrogen, continue stirring until uniform, add the catalyst, raise the temperature to 45-95°C, keep stirring for 3-10 hours, after the reaction is completed, remove the solvent under reduced pressure, wash and dry, and obtain a modified magnesium hydroxide flame retardant.

2. The method for preparing a wet modified magnesium hydroxide flame retardant according to claim 1, wherein: In the magnesium hydroxide particle mixed solution of step 1, the mass volume ratio of magnesium hydroxide particles to deionized water is 1 g:(10-50) mL; in the aminosilane mixed solution of step 1, the mass volume ratio of aminosilane coupling agent, ethanol and deionized water is (1.2-5.6) g:(70-90) mL:(10-30) mL.

3. The method for preparing a wet modified magnesium hydroxide flame retardant according to claim 1, characterized in that: The volume ratio of the magnesium hydroxide particle mixed liquid to the aminosilane mixed liquid is 1:0.1-0.

5.

4. The method for preparing a wet modified magnesium hydroxide flame retardant according to claim 1, characterized in that: In step 2, the first organic solvent is one of acetonitrile, tetrahydrofuran, dichloromethane, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide; in step 3, the second organic solvent is one of xylene, tetrahydrofuran, ethyl acetate, 1,4-dioxane, chloroform, N,N-dimethylformamide, and N,N-dimethylacetamide.

5. The method for preparing a wet modified magnesium hydroxide flame retardant according to claim 1, characterized in that: In step 2, the aminosulfonyl chloride solution is prepared by mixing aminosulfonyl chloride and acetonitrile in a mass volume ratio of (1.1-2.2) g:(5-15) mL; and the amount of triethylamine added is 10%-30% of the mass of the aminosulfonyl chloride.

6. The method for preparing a wet modified magnesium hydroxide flame retardant according to claim 1, characterized in that: The mass volume ratio of the amination magnesium hydroxide particles, the aminosulfonyl chloride solution and the first organic solvent is 1 g: (3.2-6.4) mL: (15-35) mL.

7. The method for preparing a wet modified magnesium hydroxide flame retardant according to claim 1, characterized in that: In the step 3, the mass volume ratio of the aminosulfonamidated magnesium hydroxide particles, the formaldehyded benzoxazine and the second organic solvent is 1 g:(1.7-3.4) g:(20-60) mL.

8. The method for preparing a wet modified magnesium hydroxide flame retardant according to claim 1, characterized in that: In the step 3, the preparation method of the aldehyde-substituted benzoxazine comprises: Weigh bisphenol A, 4-aminobutyraldehyde and aniline, mix them in 1,4-dioxane, stir them thoroughly, add 37wt% formaldehyde solution, heat to 70-90°C, keep stirring for 3-8h, remove the solvent under reduced pressure, dissolve in ether again, add sodium hydroxide solution dropwise until pH=7, wash with water for at least three times, and dry under reduced pressure to obtain formaldehyde benzoxazine; Among them, the mass volume ratio of bisphenol A, 4-aminobutyraldehyde, aniline, formaldehyde solution and 1,4-dioxane is (2.3-4.6) g: (0.7-1.7) g: (0.8-1.6) g: (2.4-7.2) g: (20-60) mL.

9. A wet modified magnesium hydroxide flame retardant, characterized in that: The flame retardant is prepared by the preparation method described in claim 1.

10. Use of the wet-process modified magnesium hydroxide flame retardant according to claim 9 in rubber or plastic.

Images