Preparation method and application of organic-inorganic hybrid magnesium hydroxide flame retardant
By introducing nitrogen and phosphorus elements and using phosphazene to coat magnesium hydroxide, the problems of poor compatibility and large addition amount in flame retardant applications are solved, and efficient flame retardant effect and good compatibility are achieved.
Patent Information
- Application Number
- CN202411962603.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-03-28
AI Technical Summary
Magnesium hydroxide has problems with positive charge, hydrophilicity and high surface energy in flame retardant applications, resulting in uneven dispersion in the matrix, poor compatibility, and large amount of addition affects processing and mechanical properties.
By introducing nitrogen and phosphorus elements, magnesium hydroxide is coated with phosphazene to form a synergistic effect of nitrogen, phosphorus and magnesium hydroxide, improving its compatibility with the polymer matrix.
The flame retardant efficiency of magnesium hydroxide flame retardant is improved, compatibility with polymer matrix is enhanced, the amount of addition is reduced, and the adverse effects on the processing and mechanical properties of polymer substrates are reduced.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of flame retardant modification and its application in flame retardant composite materials, and relates to a surface modification method of organic-inorganic hybrid flame retardant magnesium hydroxide and a method for modifying ethylene-vinyl acetate copolymer material with the magnesium hydroxide flame retardant. Background Art
[0002] The characteristics of polymer materials such as light weight, easy processing and high performance are driving the development of the materials industry. Since polymer materials are mainly composed of hydrocarbon elements, they are highly flammable, which leads to frequent fire incidents. Usually, corrosive or toxic gases and smoke are produced during the combustion process, causing serious damage to people and property. Therefore, it is particularly important to study and prepare flame-retardant polymer materials. The production and use of flame retardants and flame retardant materials, as well as the harm to human health and the environment during fires, have received more and more widespread attention. Research on flame retardants and flame retardant materials that meet both fire safety standards and human health and environmental friendliness requirements has become the development direction of the flame retardant field.
[0003] Magnesium hydroxide is a green flame retardant. It generates magnesium oxide and water vapor when heated. These are non-polluting, non-toxic and harmless substances. The entire production and processing process and its waste are environmentally friendly, and compared with similar metal hydroxide flame retardants, it has better smoke suppression effect. In addition, magnesium hydroxide has a large heat capacity and absorbs a large amount of heat during thermal decomposition, thereby reducing the rate of thermal decomposition of the substrate. Although magnesium hydroxide has many advantages, there are still some problems in the process of flame retardant application. First, the surface of magnesium hydroxide crystals is positively charged and is a hydrophilic substance with high surface energy, which leads to uneven dispersion in the matrix and agglomeration. Second, many polymer matrix materials show strong hydrophobicity, and the compatibility between the two is poor during contact. Third, in the process of use, in order to meet the flame retardant requirements, the amount of addition will be very large, which will have a great impact on the processing properties and mechanical properties of the polymer substrate. This limits the application and development of magnesium hydroxide, so it is particularly important to modify magnesium hydroxide, and the efficient flame retardant technology of magnesium hydroxide is still a problem to be solved. Judging from the current research progress, modifying magnesium hydroxide in a variety of ways and seeking more efficient surface modifiers are becoming the future direction of magnesium hydroxide flame retardant modification. Summary of the invention
[0004] One of the purposes of the present invention is to provide a method for surface modification of magnesium hydroxide to obtain an organic-inorganic hybrid flame retardant and improve its compatibility with a polymer matrix; the second purpose is to provide a method for preparing a flame-retardant EVA composite material using magnesium hydroxide. The present invention introduces elements such as nitrogen and phosphorus, uses phosphazene and magnesium hydroxide as raw materials, and then uses a physical coating method to coat phosphazene on the surface of magnesium hydroxide to modify the magnesium hydroxide, thereby obtaining a magnesium hydroxide flame retardant with good compatibility and high efficiency. The surface-modified magnesium hydroxide flame retardant is blended with a polymer matrix to obtain a flame-retardant composite material.
[0005] To achieve the above object, the present invention adopts the following technical solution:
[0006] The preparation and application of an organic-inorganic hybrid magnesium hydroxide flame retardant provided by the present invention comprises the following steps:
[0007] (1) Mix phosphazene, nucleophile and magnesium hydroxide (MH) in tetrahydrofuran (THF) solution and stir at room temperature for 2 h;
[0008] (2) adding the catalyst dropwise to the solution of step (1), heating to 50° C. and stirring for 2-5 h, then heating to 80° C. and stirring for 5-10 h;
[0009] (3) The product obtained in step (2) was washed with ethanol and water for several times, and dried at 80° C. to obtain the final modified product.
[0010] (4) Blending the surface-modified magnesium hydroxide, ethylene-vinyl acetate copolymer, antioxidant and lubricant in an internal mixer.
[0011] (5) Extruding the rubber material obtained in step (4) through a twin-screw extruder to obtain a flame-retardant EVA composite material.
[0012] The preparation and application of the above-mentioned organic-inorganic hybrid magnesium hydroxide flame retardant, wherein the phosphazene is one or more combinations of hexachlorocyclotriphosphazene, pentachlorocyclotriphosphazene, hexafluorocyclotriphosphazene and their derivatives, and the weight of the phosphazene is 0.5-10% of the weight of the mixture in step (1).
[0013] The preparation and application of the above-mentioned organic-inorganic hybrid magnesium hydroxide flame retardant, the nucleophilic reagent includes one or more amine nucleophilic reagents such as p-phenylenediamine, o-phenylenediamine, m-phenylenediamine, aniline, etc., and the weight of the nucleophilic reagent is 0.5-10% of the weight of the mixture in step (1).
[0014] The preparation and application of the above-mentioned organic-inorganic hybrid magnesium hydroxide flame retardant, the magnesium hydroxide is one or more combinations of nano- and micron-sized magnesium hydroxide, and the weight of the magnesium hydroxide is 5-60% of the weight of the mixture in step (1).
[0015] The preparation and application of the above-mentioned organic-inorganic hybrid magnesium hydroxide flame retardant, the catalyst includes one or more amine catalysts such as triethylamine, N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine, N,N-diethylpiperazine, etc.
[0016] The preparation and application of the above-mentioned organic-inorganic hybrid magnesium hydroxide flame retardant, the antioxidant includes one or more combinations of phosphite stabilizers, polyhedral hindered phenol flame retardants, and thioester flame retardants.
[0017] The preparation and application of the above-mentioned organic-inorganic hybrid magnesium hydroxide flame retardant, the lubricant is one or more lubricants such as zinc stearate, calcium stearate, magnesium stearate, etc.
[0018] In the preparation and application of the above organic-inorganic hybrid magnesium hydroxide flame retardant, the temperature of the internal mixer is set to 130-180°C, preferably 140°C.
[0019] The invention discloses the preparation and application of an organic-inorganic hybrid magnesium hydroxide flame retardant. The magnesium hydroxide flame retardant is the organic-inorganic hybrid magnesium hydroxide flame retardant prepared by the above steps (1) to (3). The application of the organic-inorganic hybrid magnesium hydroxide flame retardant is to prepare a flame-retardant EVA composite material by the above steps (4) to (5).
[0020] The beneficial effects of the present invention are:
[0021] (1) The present invention develops an organic-inorganic hybrid magnesium hydroxide flame retardant, by coating magnesium hydroxide with phosphazene, introducing nitrogen and phosphorus elements, forming a synergistic effect of nitrogen, phosphorus and magnesium hydroxide, and improving the flame retardant efficiency of the magnesium hydroxide flame retardant.
[0022] (2) The new magnesium hydroxide flame retardant coated with phosphazene has better compatibility with the polymer matrix. Compared with the traditional magnesium hydroxide flame retardant, it can achieve the same flame retardant effect with a smaller addition amount and has less adverse effects on the processing performance and mechanical properties of the polymer substrate. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 This is a diagram of the device for preparing the organic-inorganic hybrid magnesium hydroxide flame retardant in Example 1-3;
[0024] Figure 2 This is the Fourier infrared image of the surface modified magnesium hydroxide flame retardant prepared in Example 1. DETAILED DESCRIPTION
[0025] The present invention is further described below in conjunction with specific examples. Obviously, the described examples are only some preferred embodiments of the present invention, and the present invention is not limited to these examples. The raw materials used in the following examples, unless otherwise specified, can be obtained from conventional commercial sources.
[0026] Example 1
[0027] A certain amount of hexachlorotricyclophosphinate (HCCP), p-phenylenediamine (PDA) and magnesium hydroxide (MH) were mixed in a tetrahydrofuran solution, stirred at room temperature for 2 hours, and then a certain amount of triethylamine was added dropwise to the solution, heated to 50°C and stirred for 3 hours, and finally heated to 80°C and stirred for 7 hours. Among them, HCCP washed the final product with ethanol and water several times and dried it at 80°C to obtain a surface-modified magnesium hydroxide flame retardant HCCP-PDA-MH. The obtained HCCP-PDA-MH was subjected to infrared analysis, and 100g HCCP-PDA-MH, 100g ethylene vinyl acetate (EVA18), antioxidant 168, antioxidant 1010, and zinc stearate were blended in an internal mixer at 140°C to obtain a rubber compound in which the matrix and the modified flame retardant were evenly mixed. The rubber compound obtained by mixing evenly using the above method was pressed into sheets at 140°C for 10 minutes in a tablet press, and cut into strips with widths of 6.5 mm and 13 mm for vertical combustion and limiting oxygen index tests; the rubber compound obtained by mixing evenly using the above method was extruded and granulated through a twin-screw extruder to obtain flame-retardant EVA composite material particles, and the obtained rubber pellets were injection molded into standard strips for mechanical property testing.
[0028] Example 2
[0029] The specific experimental steps are the same as those in Example 1, wherein the weight fraction of HCCP-PDA-MH in the rubber mixture is 30%.
[0030] Example 3
[0031] The specific experimental steps are the same as those in Example 1, wherein the weight fraction of HCCP-PDA-MH in the rubber mixture is 80%.
[0032] Comparative Example 1
[0033] 100g of magnesium hydroxide, 100g of EVA18, antioxidant 168, antioxidant 1010, and zinc stearate were blended in an internal mixer at 140°C to obtain a rubber compound in which the matrix and the modified flame retardant were uniformly mixed. The rubber compound obtained by the above method was tableted in a tablet press at 140°C for 10 minutes, and cut into strips with a width of 6.5mm and 13mm for vertical combustion and limiting oxygen index tests; the rubber compound obtained by the above method was extruded and granulated by a twin-screw extruder to obtain flame-retardant EVA composite material particles, and the obtained rubber particles were injection molded into standard strips for mechanical property testing.
[0034] Characterization and performance testing
[0035] (1) Fourier transform infrared spectroscopy (FT IR)
[0036] The HCCP-PDA-MH prepared in Example 1 and Comparative Example 1 was characterized by Fourier transform infrared spectrometer Spectrum 100. The test results are shown in Figure 1 .Depend on Figure 1 It can be seen that the PN characteristic peak is visible in the infrared spectrum of HCCP-PDA-MH, indicating that hexachlorocyclotriphosphazene has been successfully coated on the surface of magnesium hydroxide.
[0037] (2) Flame retardant performance test
[0038] The flame retardant EVA composite materials prepared in Examples 1-3 and Comparative Example 1 were tested for limiting oxygen index (LOI) using an oxygen index tester (JF-3), and the test results are shown in Table 1. As can be seen from the results in Table 1, the flame retardant efficiency of HCCP-PDA-MH is higher than that of unmodified MH, the limiting oxygen index is improved, and can reach the VO level. As the weight fraction of HCCP-PDA-MH increases, the LOI of the obtained EVA composite material is higher, and when the addition amount is only 30%, the sample burns without dripping.
[0039] Table 1 Flame retardant effect comparison table
[0040] sample LOI UL-94 Rating Dripping EVA 20.5 NR YES Example 1 34.3 V-0 NO Example 2 31.7 V-0 NO Example 3 38.2 V-0 NO Comparative Example 1 28.6 NR YES
[0041] (3) Mechanical properties test
[0042] The tensile properties of Example 1 and Comparative Example 1 were tested using a universal material testing machine, and the test specimens were ISO527-21A standard specimens (80*10*4mm). The test results are shown in Table 2. From the results in Table 2, it can be seen that even with the same amount of flame retardant added, the tensile strength is higher than that of Comparative Example 1, and the compatibility of the surface HCCP-PDA-MH with the matrix is better than that of the unmodified MH.
[0043] Table 2 Mechanical properties comparison table
[0044]
[0045]
[0046] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with the profession can make some changes or modify the technical content disclosed above to an equivalent embodiment of equivalent changes without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.
Claims
1. A method for preparing an organic-inorganic hybrid magnesium hydroxide flame retardant, characterized in that: The steps include: (1) mixing phosphazene, a nucleophilic agent and magnesium hydroxide (MH) in a tetrahydrofuran (THF) solution and stirring at room temperature until the mixture is uniformly mixed; (2) adding the catalyst dropwise to the solution of step (1), heating to 50° C. and stirring for 2-5 h, then heating to 80° C. and stirring for 5-10 h; (3) washing the product obtained in step (2) with ethanol and water for several times, and drying at 80° C. to obtain surface-modified magnesium hydroxide; (4) blending the surface-modified magnesium hydroxide, ethylene-vinyl acetate copolymer, antioxidant, and lubricant in an internal mixer; (5) Extruding the rubber material obtained in step (4) through a twin-screw extruder to obtain a flame-retardant EVA composite material.
2. The method for preparing an organic-inorganic hybrid magnesium hydroxide flame retardant according to claim 1, characterized in that: The phosphazene is one or more of hexachlorocyclotriphosphazene, pentachlorocyclotriphosphazene, hexafluorocyclotriphosphazene and their derivatives, and the weight of the phosphazene is 0.5-10% of the weight of the mixture in step (1).
3. The preparation and application of an organic-inorganic hybrid magnesium hydroxide flame retardant according to claim 1, characterized in that: The nucleophilic reagent includes one or more amine nucleophilic reagents such as p-phenylenediamine, o-phenylenediamine, m-phenylenediamine, aniline, etc. The weight of the nucleophilic reagent is 0.5-10% of the weight of the mixture in step (1).
4. The method for preparing an organic-inorganic hybrid magnesium hydroxide flame retardant according to claim 1, characterized in that: The magnesium hydroxide is one or more combinations of nano-sized and micron-sized magnesium hydroxides, and the weight of the magnesium hydroxide is 5-60% of the weight of the mixture in step (1).
5. The method for preparing an organic-inorganic hybrid magnesium hydroxide flame retardant according to claim 1, characterized in that: The catalyst includes one or more amine catalysts such as triethylamine, N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine, and N,N-diethylpiperazine.
6. The method for preparing an organic-inorganic hybrid magnesium hydroxide flame retardant according to claim 1, characterized in that: The antioxidant includes one or more combinations of phosphite stabilizers, polyhedral hindered phenol flame retardants, and thioester flame retardants.
7. The method for preparing an organic-inorganic hybrid magnesium hydroxide flame retardant according to claim 1, characterized in that: The lubricant is one or more lubricants such as zinc stearate, calcium stearate, magnesium stearate, etc.
8. The method for preparing an organic-inorganic hybrid magnesium hydroxide flame retardant according to claim 1, characterized in that: The temperature of the internal mixer is set at 130-180°C.
9. The method for preparing an organic-inorganic hybrid magnesium hydroxide flame retardant according to claim 8, characterized in that: The temperature of the internal mixer was set at 140°C.
10. An application of an organic-inorganic hybrid magnesium hydroxide flame retardant, characterized in that: The magnesium hydroxide flame retardant is a flame retardant composite material prepared from the organic-inorganic hybrid magnesium hydroxide flame retardant according to any one of claims 1 to 9.