Flame-retardant magnesium hydroxide for polypropylene film materials

Abstract

The present application relates to a kind of polypropylene film material with flame-retardant magnesium hydroxide, its preparation method includes the following steps: step 1, preparation of ethylene magnesium hydroxide;Step 2, preparation of activated magnesium hydroxide;Step 3, preparation of flame-retardant magnesium hydroxide.The present application prepares a kind of flame-retardant material suitable for polypropylene film material, which is prepared after modification treatment with magnesium hydroxide as base material, the flame-retardant magnesium hydroxide prepared not only greatly improves the flame-retardant efficiency, and has good reinforcing effect on the mechanical strength, impact resistance and other aspects of polypropylene film material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flame-retardant materials, in particular to a kind of flame-retardant magnesium hydroxide for polypropylene film material. BACKGROUND

[0002] At present, high-performance composite materials applied in aerospace, automobile manufacturing, building materials and other fields are mostly prepared by impregnating fibers with thermosetting resin and then curing through multi-layer compounding. However, due to the irreversible nature of thermosetting materials, the prepared composite materials cannot be processed and reused after being discarded, causing material waste and environmental pollution. In addition, most thermosetting composite materials have long curing time and multiple preparation steps, resulting in low production efficiency. The use of thermoplastic film or plate materials to replace traditional thermosetting resins has become a trend in the development of high-performance composite materials in the future. Polypropylene is widely used in automobile manufacturing, building materials, aerospace, food and drug packaging and other fields due to its excellent mechanical properties, thermal stability, corrosion resistance and easy processing.

[0003] In recent years, polypropylene co-extrusion film composite materials have gradually attracted attention. For composite materials applied in aerospace, automobile manufacturing and other fields, water resistance, oxygen resistance and flame retardance are crucial, which directly affect the application range of the materials. However, polypropylene material itself has weak oxygen resistance and belongs to low-barrier polymer materials. In addition, polypropylene is a non-self-supporting and flammable polymer with fast flame propagation speed and low oxygen index, which seriously affects its safety during use. Therefore, a large amount of flame retardant needs to be added.

[0004] With the increasing awareness of the necessity of environmental protection in society, people's requirements for the environmental protection of flame retardants are also increasing. However, although existing antimony bromine-based flame retardants have the advantages of high flame retardant efficiency and low addition amount, they produce a large amount of smoke and toxic and corrosive gases during combustion, which is extremely harmful to people and the environment. Inorganic flame retardants are the direction of flame retardant technology development due to their non-toxicity, smoke suppression, low toxicity of combustion products and non-pollution of the environment. Among them, magnesium hydroxide is an excellent environmentally friendly inorganic flame retardant with non-toxicity, environmental protection, high decomposition temperature and other advantages. However, its flame retardant efficiency is low, the addition amount is large, and it has a large impact on the mechanical properties of the substrate, which limits its application. SUMMARY

[0005] In view of the problems existing in the prior art, the purpose of the present application is to provide a flame-retardant magnesium hydroxide for polypropylene film material.

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

[0007] In a first aspect, the present application provides a preparation method of a flame-retardant magnesium hydroxide for polypropylene film material, comprising the following steps:

[0008] Step 1, preparation of ethylene magnesium hydroxide:

[0009] The magnesium hydroxide powder is weighed and mixed in a mixture of ethanol and deionized water. After stirring until uniform, silane coupling agent A-172 is added dropwise. The reaction is carried out by heating, followed by centrifugation, washing, and drying to obtain ethylene magnesium hydroxide.

[0010] Step 2, preparation of activated magnesium hydroxide:

[0011] The ethylene magnesium hydroxide is weighed and dispersed in toluene. 4-amino-2-mercapto pyrimidine is added and dispersed again. Nitrogen gas is then introduced as a protective gas. A photoinitiator is added, and the reaction is carried out under ultraviolet light stirring. After the reaction is completed, centrifugation, washing, and drying are carried out to obtain activated magnesium hydroxide.

[0012] Step 3, preparation of flame-retardant magnesium hydroxide:

[0013] Phenylenediamine phosphoryl chloride is weighed and added to tetrahydrofuran. After stirring until uniform, activated magnesium hydroxide is added. Triethylamine is added dropwise, and nitrogen gas is introduced as a protective gas. The reaction is carried out by refluxing and stirring. After the reaction is completed, centrifugation, washing, and drying are carried out to obtain flame-retardant magnesium hydroxide.

[0014] Preferably, in step 1, the particle size of the magnesium hydroxide (MH) powder is 10-20 μm.

[0015] Preferably, in step 1, the mass-volume ratio of magnesium hydroxide powder, ethanol, and deionized water is 1 g:(5-10) mL:(2-6) mL.

[0016] Preferably, in step 1, the amount of silane coupling agent A-172 added is 5%-15% of the mass of the magnesium hydroxide powder.

[0017] Preferably, in step 1, the reaction temperature is 50-60°C, and the reaction time is 5-10 h.

[0018] Preferably, in step 2, the mass-volume ratio of activated magnesium hydroxide, 4-amino-2-mercapto pyrimidine, and toluene is 1 g:(0.16-0.32) g:(10-20) mL.

[0019] Preferably, in step 2, the photoinitiator is any one of benzoin dimethyl ether, benzoin diethyl ether, or 2,2-diethoxyacetophenone; the amount of photoinitiator added is 1%-6% of the mass of 4-amino-2-mercapto pyrimidine.

[0020] Preferably, in step 2, the irradiation intensity of ultraviolet light is 10-50 mw / cm 2 , the wavelength is 365 nm, and the reaction time is 1-3 h.

[0021] Preferably, in the step 3, the o-phenylenediamine phosphorus oxychloride is obtained by reacting o-phenylenediamine and phosphorus oxychloride in an organic solvent, the reaction temperature is 60℃, the reaction time is 8h, and the mass ratio of o-phenylenediamine to phosphorus oxychloride is 0.15:0.16.

[0022] Preferably, in the step 3, the mass-volume ratio of the activated magnesium hydroxide, o-phenylenediamine phosphorus oxychloride and tetrahydrofuran is 1g:(0.16-0.32)g:(10-20)mL.

[0023] Preferably, in the step 3, the amount of triethylamine added is 3%-10% of the mass of o-phenylenediamine phosphorus oxychloride.

[0024] Preferably, in the step 3, the reaction temperature is 60-80℃, and the reaction time is 10-20h.

[0025] In a second aspect, the present application provides a flame-retardant magnesium hydroxide for polypropylene film material, which is prepared by the above preparation method.

[0026] The present application has the following advantages:

[0027] 1. The present application prepares a flame-retardant material suitable for polypropylene film material, which is prepared by modifying magnesium hydroxide as a base material. The prepared flame-retardant magnesium hydroxide not only greatly improves the flame-retardant efficiency, but also has a good reinforcing effect on the mechanical strength and impact resistance of the polypropylene film material.

[0028] 2. The flame retardant of the present application is a shell-core type material coated with organic-inorganic. The preparation process includes: first, treating magnesium hydroxide with a vinyl silane coupling agent to obtain vinylated magnesium hydroxide; then, combining 4-amino-2-mercaptopyrimidine with the vinylated magnesium hydroxide through a click reaction of thiol-double bond to obtain activated magnesium hydroxide containing a sulfide group; and then combining the amino group in the activated magnesium hydroxide with o-phenylenediamine phosphorus oxychloride to generate a phosphoramide group through the combination of phosphorus oxychloride-amino group, and finally obtaining a flame retardant containing sulfide groups, phosphoramide groups, pyrimidine groups and other groups on the surface.

[0029] 3. The flame retardant prepared by the present application is applied to polypropylene film material, and it is found that compared with traditional magnesium hydroxide flame retardants, the same flame-retardant efficiency can be maintained while the amount of use is greatly reduced, the smoke density is low, and the strength and impact resistance of the polypropylene film material are improved to a certain extent. BRIEF DESCRIPTION OF DRAWINGS

[0030] The present application is further illustrated by the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present application. Other drawings can be obtained by those skilled in the art without creative labor on the basis of the following drawings.

[0031] Figure 1 is a scanning electron microscope diagram of the flame-retardant magnesium hydroxide prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0032] The technical solutions of the present application are described below through specific examples. It should be understood that the one or more method steps mentioned in the present application do not exclude other method steps before and after the described combination steps or other method steps inserted between the explicitly mentioned steps; it should also be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool to identify each method step and is not a limitation on the arrangement order of each method step or a limitation on the scope of the present application that can be implemented, and changes or adjustments of the relative relationship without substantial changes in the technical content are also considered as the scope of the present application that can be implemented.

[0033] The present application is further described below in conjunction with the following examples.

[0034] Example 1

[0035] A method for preparing a flame-retardant magnesium hydroxide for a polypropylene film material, comprising the following steps:

[0036] Step 1, preparing ethyleneated magnesium hydroxide:

[0037] Magnesium hydroxide powder (MH) with a particle size of 10-20 μm was weighed and mixed in a mixture of ethanol and deionized water, the mass-volume ratio of magnesium hydroxide powder, ethanol and deionized water was 1 g:8 mL:4 mL, after stirring to uniformity, silane coupling agent A-172 was added dropwise, the amount of addition was 10% of the mass of magnesium hydroxide powder, the temperature was raised to 55°C, and stirring was carried out for 6 h, then centrifugation, washing and drying were carried out to obtain ethyleneated magnesium hydroxide;

[0038] Step 2, preparing activated magnesium hydroxide:

[0039] Ethyleneated magnesium hydroxide was weighed and dispersed in toluene, 4-amino-2-mercapto pyrimidine was added, the mass-volume ratio of activated magnesium hydroxide, 4-amino-2-mercapto pyrimidine and toluene was 1 g:0.24 g:15 mL, uniformity was again achieved, then nitrogen gas was introduced as a protective gas, photoinitiator benzoin dimethyl ether was added, stirring was carried out under ultraviolet light with a wavelength of 365 nm and an irradiation intensity of 25 mw / cm 2 , for 2 h, after the reaction was completed, centrifugation, washing and drying were carried out to obtain activated magnesium hydroxide;

[0040] Step 3, preparing flame-retardant magnesium hydroxide:

[0041] The o-phenylenediamine and phosphorus oxychloride are weighed and mixed into dichloroethane, and the reaction is carried out at a temperature of 60°C for 8 hours, with the mass ratio of o-phenylenediamine to phosphorus oxychloride being 0.15:0.16; after the reaction is completed, the o-phenylenediamine phosphorus oxychloride is obtained after being reduced in pressure, washed, and dried;

[0042] The o-phenylenediamine phosphorus oxychloride is weighed and added into tetrahydrofuran, and stirred until uniform; activated magnesium hydroxide is then added, with the mass volume ratio of activated magnesium hydroxide, o-phenylenediamine phosphorus oxychloride, and tetrahydrofuran being 1g:0.24g:15mL; triethylamine is added dropwise, with the amount of triethylamine being 8% of the mass of o-phenylenediamine phosphorus oxychloride; nitrogen gas is introduced as a protective gas; the mixture is stirred at reflux at 70°C for 15 hours; after the reaction is completed, the flame-retardant magnesium hydroxide is obtained after being centrifuged, washed, and dried.

[0043] Example 2

[0044] A method for preparing flame-retardant magnesium hydroxide for a polypropylene film material, comprising the following steps:

[0045] Step 1: Preparation of ethyleneated magnesium hydroxide

[0046] Magnesium hydroxide powder (MH) with a particle size of 10-20μm is weighed and mixed into a mixture of ethanol and deionized water, with the mass volume ratio of magnesium hydroxide powder, ethanol, and deionized water being 1g:5mL:2mL; silane coupling agent A-172 is added dropwise, with the amount of silane coupling agent A-172 being 5% of the mass of magnesium hydroxide powder; the mixture is stirred until uniform, and then heated to 50°C and stirred for 5 hours; the ethyleneated magnesium hydroxide is obtained after being centrifuged, washed, and dried.

[0047] Step 2: Preparation of activated magnesium hydroxide

[0048] Ethyleneated magnesium hydroxide is weighed and dispersed in toluene; 4-amino-2-mercaptopyrimidine is added, with the mass volume ratio of activated magnesium hydroxide, 4-amino-2-mercaptopyrimidine, and toluene being 1g:0.16g:10mL; the mixture is again dispersed until uniform; nitrogen gas is introduced as a protective gas; photoinitiator benzpinacol dimethyl ether is added; the mixture is stirred under ultraviolet light with an intensity of 10mw / cm 2 and a wavelength of 365nm for 1 hour; the activated magnesium hydroxide is obtained after being centrifuged, washed, and dried.

[0049] Step 3: Preparation of flame-retardant magnesium hydroxide

[0050] The o-phenylenediamine and phosphorus oxychloride are weighed and mixed into dichloroethane, and the reaction is carried out at a temperature of 60°C for 8 hours, with the mass ratio of o-phenylenediamine to phosphorus oxychloride being 0.15:0.16; after the reaction is completed, the o-phenylenediamine phosphorus oxychloride is obtained after being reduced in pressure, washed, and dried;

[0051] The o-phenylenediamine phosphorus oxychloride is weighed and added to tetrahydrofuran, stirred until uniform, then activated magnesium hydroxide is added, the mass-volume ratio of activated magnesium hydroxide, o-phenylenediamine phosphorus oxychloride and tetrahydrofuran is 1 g:0.16 g:10 mL, triethylamine is added, the amount of triethylamine is 3% of the mass of o-phenylenediamine phosphorus oxychloride, nitrogen gas is introduced as a protective gas, reflux stirring is carried out at 60°C for 10 h, after the reaction is completed, centrifugation, washing and drying are carried out, and the flame-retardant magnesium hydroxide is obtained.

[0052] Example 3

[0053] A method for preparing flame-retardant magnesium hydroxide for a polypropylene film material, comprising the following steps:

[0054] Step 1, preparation of ethyleneated magnesium hydroxide:

[0055] The magnesium hydroxide powder (MH) with a particle size of 10-20 μm is weighed and mixed in a mixture of ethanol and deionized water, the mass-volume ratio of magnesium hydroxide powder, ethanol and deionized water is 1 g:10 mL:6 mL, after stirring until uniform, silane coupling agent A-172 is added dropwise, the amount of silane coupling agent A-172 is 15% of the mass of magnesium hydroxide powder, the temperature is raised to 60°C, stirring is carried out for 10 h, then centrifugation, washing and drying are carried out, and the ethyleneated magnesium hydroxide is obtained;

[0056] Step 2, preparation of activated magnesium hydroxide:

[0057] The ethyleneated magnesium hydroxide is weighed and dispersed in toluene, 4-amino-2-mercaptopyrimidine is added, the mass-volume ratio of activated magnesium hydroxide, 4-amino-2-mercaptopyrimidine and toluene is 1 g:0.32 g:20 mL, then it is dispersed again, nitrogen gas is introduced as a protective gas, photoinitiator benzoin diethyl ether is added, stirring is carried out under ultraviolet light with an intensity of 50 mw / cm 2 , wavelength of 365 nm for 3 h, after the reaction is completed, centrifugation, washing and drying are carried out, and the activated magnesium hydroxide is obtained;

[0058] Step 3, preparation of flame-retardant magnesium hydroxide:

[0059] The o-phenylenediamine and phosphorus oxychloride are weighed and mixed into dichloroethane, the reaction is carried out by heating, the reaction temperature is 60°C, the reaction time is 8 h, the mass ratio of o-phenylenediamine and phosphorus oxychloride is 0.15:0.16, after the reaction is completed, the o-phenylenediamine phosphorus oxychloride is obtained by reducing pressure, washing and drying;

[0060] The o-phenylenediamine phosphorus oxychloride is weighed and added to tetrahydrofuran, stirred until uniform, then activated magnesium hydroxide is added, the mass-volume ratio of activated magnesium hydroxide, o-phenylenediamine phosphorus oxychloride and tetrahydrofuran is 1 g:0.32 g:20 mL, triethylamine is added, the amount is 10% of the mass of o-phenylenediamine phosphorus oxychloride, nitrogen is introduced as a protective gas, reflux stirring is carried out at 80℃ for 20 h, after the reaction is completed, centrifugation, washing and drying are carried out, and the flame-retardant magnesium hydroxide is obtained.

[0061] Example 4

[0062] A preparation method of flame-retardant magnesium hydroxide for polypropylene film material, comprising the following steps:

[0063] Step 1, preparation of ethyleneated magnesium hydroxide:

[0064] The magnesium hydroxide powder (MH) with a particle size of 10-20 μm is weighed and mixed in a mixture of ethanol and deionized water, the mass-volume ratio of magnesium hydroxide powder, ethanol and deionized water is 1 g:6 mL:5 mL, after stirring until uniform, silane coupling agent A-172 is added dropwise, the amount is 12% of the mass of magnesium hydroxide powder, the temperature is raised to 60℃, stirring is carried out for 5 h, then centrifugation, washing and drying are carried out, and the ethyleneated magnesium hydroxide is obtained;

[0065] Step 2, preparation of activated magnesium hydroxide:

[0066] The ethyleneated magnesium hydroxide is weighed and dispersed in toluene, 4-amino-2-mercaptopyrimidine is added, the mass-volume ratio of activated magnesium hydroxide, 4-amino-2-mercaptopyrimidine and toluene is 1 g:0.24 g:15 mL, then dispersed again, nitrogen is introduced as a protective gas, photoinitiator benzoin diethyl ether is added, stirring is carried out under ultraviolet light with an intensity of 30 mw / cm 2 , wavelength of 365 nm for 2 h, after the reaction is completed, centrifugation, washing and drying are carried out, and the activated magnesium hydroxide is obtained;

[0067] Step 3, preparation of flame-retardant magnesium hydroxide:

[0068] The o-phenylenediamine and phosphorus oxychloride are weighed and mixed into dichloroethane, the reaction is carried out by heating, the reaction temperature is 60℃, the reaction time is 8 h, the mass ratio of o-phenylenediamine and phosphorus oxychloride is 0.15:0.16, after the reaction is completed, the o-phenylenediamine phosphorus oxychloride is obtained after pressure reduction, washing and drying;

[0069] The o-phenylenediamine phosphorus oxychloride is weighed and added to tetrahydrofuran, stirred until uniform, then activated magnesium hydroxide is added, the mass-volume ratio of activated magnesium hydroxide, o-phenylenediamine phosphorus oxychloride and tetrahydrofuran is 1g:0.24g:15mL, triethylamine is added, the amount is 5% of the mass of o-phenylenediamine phosphorus oxychloride, nitrogen is introduced as a protective gas, refluxed and stirred at 80°C for 18h, after the reaction is completed, centrifugation, washing and drying are performed to obtain the flame-retardant magnesium hydroxide.

[0070] Comparative Example 1

[0071] A preparation method of flame-retardant magnesium hydroxide for polypropylene film material, using the ethylated magnesium hydroxide in Example 1 as the flame-retardant magnesium hydroxide, comprising the following steps:

[0072] The magnesium hydroxide powder (MH) with a particle size of 10-20μm is weighed and mixed in a mixture of ethanol and deionized water, the mass-volume ratio of magnesium hydroxide powder, ethanol and deionized water is 1g:8mL:4mL, after stirring until uniform, silane coupling agent A-172 is added dropwise, the amount is 10% of the mass of magnesium hydroxide powder, heated to 55°C, stirred for 6h, then centrifuged, washed and dried to obtain the ethylated magnesium hydroxide, i.e. the flame-retardant magnesium hydroxide.

[0073] Comparative Example 2

[0074] A preparation method of flame-retardant magnesium hydroxide for polypropylene film material, using the activated magnesium hydroxide in Example 1 as the flame-retardant magnesium hydroxide, comprising the following steps:

[0075] Step 1, preparation of ethylated magnesium hydroxide:

[0076] The magnesium hydroxide powder (MH) with a particle size of 10-20μm is weighed and mixed in a mixture of ethanol and deionized water, the mass-volume ratio of magnesium hydroxide powder, ethanol and deionized water is 1g:8mL:4mL, after stirring until uniform, silane coupling agent A-172 is added dropwise, the amount is 10% of the mass of magnesium hydroxide powder, heated to 55°C, stirred for 6h, then centrifuged, washed and dried to obtain the ethylated magnesium hydroxide;

[0077] Step 2, preparation of activated magnesium hydroxide:

[0078] The ethylated magnesium hydroxide is weighed and dispersed in toluene, 4-amino-2-mercaptopyrimidine is added, the mass-volume ratio of activated magnesium hydroxide, 4-amino-2-mercaptopyrimidine and toluene is 1g:0.24g:15mL, then dispersed again, nitrogen is introduced as a protective gas, photoinitiator benzoin dimethyl ether is added, stirred under ultraviolet light with an intensity of 25mw / cm 2 , wavelength of 365nm for 2h, after the reaction is completed, centrifugation, washing and drying are performed to obtain the activated magnesium hydroxide, i.e. the flame-retardant magnesium hydroxide.

[0079] Comparative Example 3

[0080] A preparation method of a flame-retardant magnesium hydroxide for polypropylene film material, using a mixture of a reaction product of o-phenylenediamine phosphorus oxychloride and 4-amino-2-mercaptopyrimidine and magnesium hydroxide as the flame-retardant magnesium hydroxide, comprising the following steps:

[0081] o-phenylenediamine phosphorus oxychloride is weighed and added to tetrahydrofuran, stirred until uniform, then magnesium hydroxide and 4-amino-2-mercaptopyrimidine are added, the mass / volume ratio of magnesium hydroxide, 4-amino-2-mercaptopyrimidine, o-phenylenediamine phosphorus oxychloride and tetrahydrofuran is 1g:0.24g:0.24g:15mL, triethylamine is added dropwise, the amount is 5% of the mass of o-phenylenediamine phosphorus oxychloride, nitrogen gas is introduced as a protective gas, reflux stirring is carried out at 80℃ for 18h, after the reaction is completed, the flame-retardant magnesium hydroxide is obtained after reduction, washing and drying.

[0082] Experimental detection

[0083] The flame-retardant magnesium hydroxide prepared in Example 1 and Comparative Examples 1-3 is applied to polypropylene film material, and then the mechanical properties, flame-retardant properties and anti-aging properties of the polypropylene film material are detected.

[0084] The flame-retardant magnesium hydroxide prepared in Example 1 and Comparative Examples 1-3 and polypropylene resin (melt index 10g / 10min) are mixed in a mass ratio of 1:5, then melted and mixed uniformly in a stirrer, and then extruded in a temperature range of 180-210℃ by a twin-screw extruder, and then formed on a cooling roller to prepare flame-retardant polypropylene film material.

[0085] The prepared flame-retardant polypropylene film material is numbered respectively, and then the performance is detected, and the detection results are shown in the following table. The detection of tensile strength and elongation at break refers to the standard GB / T 1040.1-2018, the detection of impact brittle temperature refers to the standard GB / T 5470-2008, the detection of smoke density refers to the standard GB / T 8627-2007, and the detection of flame-retardant grade (UL-94) refers to the vertical burning method of the standard ANSI / UL-94-2009.

[0086] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength (MPa) 32.1 23.5 27.3 28.9 Elongation at break (%) 227 158 201 186 Charpy embrittlement temperature (°C) -37 -26 -29 -32 Smoke density rating (SDR) 48.3 67.5 59.7 53.1 UL-94 (3.2 mm) V-0 V-1 V-1 V-0

[0087] As can be seen from the detection results in the above table, the flame-retardant polypropylene film material prepared using the flame-retardant magnesium hydroxide of Example 1 has obviously stronger mechanical properties and impact resistance, and the UL-94 flame-retardant grade can reach V-0, and the smoke density grade SDR is only 48.3, indicating that it has good flame-retardant properties while maintaining a low smoke density.

[0088] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate different embodiments or examples described in the specification.

[0089] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary, and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A method for producing a flame-retardant magnesium hydroxide for a polypropylene film material, characterized by, It comprises the following steps: Step 1, preparation of ethylene magnesium hydroxide: The magnesium hydroxide powder is weighed and mixed in a mixture of ethanol and deionized water, stirred until uniform, then silane coupling agent A-172 is added dropwise, the temperature is raised for reaction, then centrifuged, washed and dried to obtain ethylene magnesium hydroxide; Step 2, preparation of activated magnesium hydroxide: The ethylene magnesium hydroxide is weighed and dispersed in toluene, 4-amino-2-mercapto pyrimidine is added, then dispersed again, then nitrogen is introduced as a protective gas, a photoinitiator is added, and the reaction is stirred under ultraviolet light, after the reaction is completed, it is centrifuged, washed and dried to obtain activated magnesium hydroxide; Step 3, preparation of flame-retardant magnesium hydroxide: The o-phenylenediamine phosphorus oxychloride is weighed and added to tetrahydrofuran, stirred until uniform, then the activated magnesium hydroxide is added, triethylamine is added dropwise, nitrogen is introduced as a protective gas, and the reaction is stirred under reflux, after the reaction is completed, it is centrifuged, washed and dried to obtain flame-retardant magnesium hydroxide.

2. The method for preparing flame-retardant magnesium hydroxide for polypropylene film material according to claim 1, characterized in that, In step 1, the mass-volume ratio of magnesium hydroxide powder, ethanol and deionized water is 1g:(5-10)mL:(2-6)mL; the amount of silane coupling agent A-172 added is 5%-15% of the mass of magnesium hydroxide powder.

3. The method for preparing flame-retardant magnesium hydroxide for polypropylene film materials according to claim 1, characterized in that, In step 1, the reaction temperature is 50-60℃, and the reaction time is 5-10h.

4. The method for preparing flame-retardant magnesium hydroxide for polypropylene film materials according to claim 1, characterized in that, In step 2, the mass-volume ratio of activated magnesium hydroxide, 4-amino-2-mercapto pyrimidine and toluene is 1g:(0.16-0.32)g:(10-20)mL.

5. The method for preparing flame-retardant magnesium hydroxide for polypropylene film materials according to claim 1, characterized in that, In step 2, the photoinitiator is any one of benzoin dimethyl ether, benzoin diethyl ether and 2,2-diethoxyacetophenone; the amount of photoinitiator added is 1%-6% of the mass of 4-amino-2-mercapto pyrimidine.

6. The method for preparing flame-retardant magnesium hydroxide for polypropylene film materials according to claim 1, characterized in that, The irradiation intensity of the ultraviolet light in step 2 is 10-50 mw / cm 2 , the wavelength is 365 nm, and the reaction time is 1-3 h.

7. The method for preparing flame-retardant magnesium hydroxide for polypropylene film materials according to claim 1, characterized in that, In step 3, the o-phenylenediamine phosphorus oxychloride is obtained by reacting o-phenylenediamine and phosphorus oxychloride in an organic solvent, the reaction temperature is 60℃, the reaction time is 8h, and the mass ratio of o-phenylenediamine to phosphorus oxychloride is 0.15:0.

16.

8. The method for preparing flame-retardant magnesium hydroxide for polypropylene film materials according to claim 1, characterized in that, In step 3, the mass-volume ratio of activated magnesium hydroxide, o-phenylenediamine phosphorus oxychloride and tetrahydrofuran is 1g:(0.16-0.32)g:(10-20)mL.

9. The method for preparing flame-retardant magnesium hydroxide for polypropylene film materials according to claim 1, characterized in that, In step 3, the reaction temperature is 60-80℃, and the reaction time is 10-20h.

10. A flame-retardant magnesium hydroxide for a polypropylene film material, characterized by, Prepared by the preparation method of claim 1.

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