Modified magnesium hydroxide for high filling material and preparation method of modified magnesium hydroxide

Abstract

The invention relates to the field of flame retardants, in particular to modified magnesium hydroxide for a high-filling material and a preparation method of the modified magnesium hydroxide. The preparation method of the modified magnesium hydroxide comprises the following steps: step 1, carrying out surface amination treatment on magnesium hydroxide particles; step 2, reacting the aminated magnesium hydroxide particles with allylsulfonyl chloride to obtain activated magnesium hydroxide particles; 3, the activated magnesium hydroxide particles react with hydroxypropyl vinyl ether, and modified magnesium hydroxide is obtained. The modified magnesium hydroxide for the high-filling material prepared by the invention has excellent flame-retardant filling property when being applied to a high-molecular material, and compared with a traditional magnesium hydroxide filler, not only is the flame retardance of the high-molecular material improved, but also the mechanical strength and the impact resistance of the high-molecular material are well improved.

Description

Technical Field

[0001] The present invention relates to the field of flame retardants, and particularly to a modified magnesium hydroxide for high-filled materials and a preparation method thereof. Background Art

[0002] High-filled materials refer to composite materials obtained by adding a large amount of fillers (usually with a mass ratio exceeding 30% and even up to 94%) to matrix materials (such as resins, rubbers, plastics, etc.) to improve material properties or reduce costs. The core lies in optimizing filler characteristics, filling processes, and interfacial interactions to ensure processability and functionality while achieving high ratios of filling.

[0003] With the continuous development of high-filled materials, how to flame-retardantly modify high-filled materials has gradually attracted people's attention. As a green and environmentally friendly inorganic flame retardant, magnesium hydroxide has been widely used and has broad development prospects. However, when magnesium hydroxide is used alone, a relatively large amount is usually required to achieve a flame-retardant effect. At the same time, its surface exhibits the property of "hydrophilic and oleophobic", making it difficult to be uniformly dispersed in polymers, resulting in weak binding force and poor compatibility with polymers. Therefore, it is very important to modify the surface of magnesium hydroxide to improve its compatibility with polymers.

[0004] Currently, the most commonly used method for modifying magnesium hydroxide is the surface modification method. The modifiers used for the surface modification of magnesium hydroxide are mainly silane coupling agents and anionic surfactants. Among them, due to the large variety and complex synthesis of silane coupling agents, and a series of problems such as low purity in the quality of many domestic coupling agent products, it is difficult to apply them to the industrial surface modification of magnesium hydroxide. In addition, although silane coupling agents and anionic surfactants can be used for the surface modification of magnesium hydroxide, the binding force between them and magnesium hydroxide is often not strong enough. Therefore, when used as a polymer flame retardant, the mechanical properties of polymer products will decline. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a modified magnesium hydroxide for high-filled materials and a preparation method thereof.

[0006] The purpose of the present invention is achieved by the following technical solutions: In the first aspect, the present invention provides a preparation method for a modified magnesium hydroxide for high-filled materials, comprising the following steps: Step 1, surface amination treatment: Mix magnesium hydroxide particles and an aqueous solution of ethanol, first stir evenly at room temperature, then add an amino-silane coupling agent, heat to reflux in a heating device, continuously stir for 2 - 6 h, and then perform suction filtration, washing, and drying to obtain aminated magnesium hydroxide particles; Step 2, surface activation treatment: Add the aminated magnesium hydroxide particles into tetrahydrofuran, disperse them evenly in an ice-water bath, then gradually add allyl sulfonyl chloride dropwise. After all the addition, heat up to room temperature, add triethylamine as an acid-binding agent, and stir at room temperature for 8 - 16 h. After the reaction is completed, remove the solvent by vacuum distillation to obtain activated magnesium hydroxide particles; Step 3, surface modification treatment: Add the activated magnesium hydroxide particles into an aqueous solution of ethanol, introduce nitrogen as a protective gas, heat up to 50 - 80 °C, then gradually add hydroxypropyl vinyl ether within half an hour, and then add an initiator dropwise within half an hour. Keep stirring at a constant temperature for 3 - 6 h. After the reaction is completed, cool and dry, then perform dialysis purification treatment, and dry again to obtain modified magnesium hydroxide.

[0007] Preferably, in the said Step 1, the particle size of the magnesium hydroxide particles is 1 - 100 μm.

[0008] Preferably, in the said Step 1, the mass fraction of the aqueous solution of ethanol is 30% - 80%, and the amino-silane coupling agent is γ-aminopropyltriethoxysilane (A-1100) or γ-aminopropyltrimethoxysilane (A-1110).

[0009] Preferably, in the said Step 1, the dosage ratio of the magnesium hydroxide particles, the amino-silane coupling agent and the aqueous solution of ethanol is 10 g : (1 - 5) g : (100 - 200) mL.

[0010] Preferably, in the said Step 2, the dosage ratio of the aminated magnesium hydroxide particles, allyl sulfonyl chloride and tetrahydrofuran is 10 g : (2.8 - 5.6) g : (100 - 200) mL.

[0011] Preferably, in the said Step 2, the addition amount of the acid-binding agent is 0.5% - 2.5% of the mass of allyl sulfonyl chloride.

[0012] Preferably, in the said Step 3, the mass fraction of the aqueous solution of ethanol is 10% - 50%, and the dosage ratio of the activated magnesium hydroxide particles, hydroxypropyl vinyl ether and the aqueous solution of ethanol is 10 g : (4.2 - 8.4) g : (100 - 300) mL.

[0013] Preferably, in the said Step 3, the initiator is an ammonium persulfate solution with a mass fraction of 1% - 5%, and the actual addition amount of ammonium persulfate is 1% - 10% of the mass of hydroxypropyl vinyl ether.

[0014] Preferably, in the said Step 3, the molecular weight cut-off MWCO of the dialysis bag for dialysis is 3000 - 5000 Da, and the dialysis treatment time is 48 - 72 h.

[0015] In a second aspect, the present invention provides a modified magnesium hydroxide, which is prepared by the above preparation method.

[0016] In a third aspect, the present invention provides a modified magnesium hydroxide for use as a flame retardant filler for polymer materials.

[0017] Preferably, the polymer material is at least one of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyimide (PI), nylon (PA), polylactic acid (PLA), polyether ether ketone (PEEK), styrene-butadiene rubber (SBR), chloroprene rubber (CR), fluororubber (FPM), ethylene-vinyl acetate copolymer (EVA).

[0018] Preferably, the addition amount of the flame retardant filler is 30%-70% of the total mass of the polymer material.

[0019] The beneficial effects of the present invention are as follows: 1. The present invention prepares a modified magnesium hydroxide for high-fill materials. When applied to polymer materials, it has excellent flame retardant filling properties. Compared with traditional magnesium hydroxide fillers, it not only improves the flame retardancy of polymer materials, but also significantly improves their mechanical strength and impact resistance.

[0020] 2. The process for preparing the modified magnesium hydroxide in the present invention includes: first, subjecting magnesium hydroxide particles to amination treatment, then reacting with allyl sulfonyl chloride containing an unsaturated double bond to carry out a sulfonyl chloride-amino binding reaction to obtain activated magnesium hydroxide particles; and then carrying out a double bond polymerization cross-linking reaction with hydroxypropyl vinyl ether also containing an unsaturated bond to finally obtain the modified magnesium hydroxide.

[0021] 3. The surface of the modified magnesium hydroxide prepared in the present invention is coated with a network cross-linked polymer structure. This polymer structure contains groups such as hydroxyl groups, ether groups, and sulfonamide groups, which not only enhances the compatibility with polymer materials, but also improves the strength, toughness, and flame retardancy of polymer materials (especially EVA) to varying degrees. Detailed embodiments

[0022] The technical solutions of the present invention are described below through specific specific examples. It should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combined steps or that other method steps can be inserted between these clearly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Moreover, unless otherwise specified, the numbers of the method steps are only convenient tools for identifying the method steps, rather than limiting the arrangement order of the method steps or the scope in which the present invention can be implemented. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope in which the present invention can be implemented.

[0023] To better understand the above technical solutions, the exemplary embodiments of the present invention will be described in more detail below. Although the 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 so that the present invention can be understood more thoroughly and the scope of the present invention can be fully conveyed to those skilled in the art.

[0024] The present invention will be further described below in conjunction with the following embodiments.

[0025] Embodiment 1 A preparation method of modified magnesium hydroxide, comprising the following steps: Step 1, surface amination treatment: Mix 10 g of 50-μm magnesium hydroxide particles and 150 mL of 60 wt% ethanol aqueous solution, first stir evenly at room temperature, then add 3 g of γ-aminopropyltriethoxysilane (A-1100), heat up to reflux in a heating device, continuously stir for 4 h, and then after suction filtration, washing and drying, obtain aminated magnesium hydroxide particles; Step 2, surface activation treatment: Add 10 g of aminated magnesium hydroxide particles to 150 mL of tetrahydrofuran, disperse evenly in an ice-water bath, then gradually dropwise add 4.2 g of allylsulfonyl chloride. After all the addition, heat up to room temperature, dropwise add triethylamine as an acid-binding agent, and the addition amount is 1.5% of the mass of allylsulfonyl chloride. Stir at room temperature for 12 h. After the reaction is completed, remove the solvent by vacuum distillation to obtain activated magnesium hydroxide particles; Step 3, surface modification treatment: 10 g of activated magnesium hydroxide particles were added to 200 mL of 30 wt% aqueous ethanol solution, nitrogen was introduced as a protective gas, the temperature was raised to 50 - 80 °C, then 6.3 g of hydroxypropyl vinyl ether was gradually added within half an hour, and then a 3 wt% ammonium persulfate solution was added dropwise within half an hour. The addition amount of ammonium persulfate was 5% of the mass of hydroxypropyl vinyl ether. After holding the temperature and stirring for 4 h, after the reaction ended, it was naturally cooled to room temperature, first subjected to vacuum drying, then placed in a dialysis bag with a molecular weight cut-off MWCO of 4000 Da, and dialyzed and purified in pure water for 60 h, and then vacuum dried again to obtain modified magnesium hydroxide.

[0026] Example 2 A preparation method of modified magnesium hydroxide, comprising the following steps: Step 1, surface amination treatment: 10 g of 50 μm magnesium hydroxide particles were mixed with 100 mL of 30 wt% aqueous ethanol solution, first stirred evenly at room temperature, then 1 g of γ-aminopropyltriethoxysilane (A-1100) was added, the temperature was raised to reflux in a heating device, and stirring was continued for 2 h. After that, it was subjected to suction filtration, washing and drying to obtain aminated magnesium hydroxide particles; Step 2, surface activation treatment: 10 g of aminated magnesium hydroxide particles were added to 100 mL of tetrahydrofuran, dispersed evenly in an ice-water bath, then 2.8 g of allyl sulfonyl chloride was gradually added dropwise. After all the addition, the temperature was raised to room temperature, and triethylamine was added dropwise as an acid-binding agent, and the addition amount was 0.5% of the mass of allyl sulfonyl chloride. Stirring was carried out at room temperature for 8 h. After the reaction ended, the solvent was removed by vacuum distillation to obtain activated magnesium hydroxide particles; Step 3, surface modification treatment: 10 g of activated magnesium hydroxide particles were added to 100 mL of 10 wt% aqueous ethanol solution, nitrogen was introduced as a protective gas, the temperature was raised to 50 °C, then 4.2 g of hydroxypropyl vinyl ether was gradually added within half an hour, and then a 1 wt% ammonium persulfate solution was added dropwise within half an hour. The addition amount of ammonium persulfate was 1% of the mass of hydroxypropyl vinyl ether. After holding the temperature and stirring for 3 h, after the reaction ended, it was naturally cooled to room temperature, first subjected to vacuum drying, then placed in a dialysis bag with a molecular weight cut-off MWCO of 3000 Da, and dialyzed and purified in pure water for 48 h, and then vacuum dried again to obtain modified magnesium hydroxide.

[0027] Example 3 A preparation method of modified magnesium hydroxide, comprising the following steps: Step 1, surface amination treatment: Mix 10 g of 50-μm magnesium hydroxide particles with 200 mL of 80 wt% ethanol aqueous solution. First, stir evenly at room temperature, then add 5 g of γ-aminopropyltriethoxysilane (A-1100). Heat up to reflux in a heating device and continuously stir for 6 h. After that, perform suction filtration, washing, and drying to obtain amino-functionalized magnesium hydroxide particles; Step 2, surface activation treatment: Add 10 g of amino-functionalized magnesium hydroxide particles to 200 mL of tetrahydrofuran. Disperse evenly in an ice-water bath, then gradually add 5.6 g of allylsulfonyl chloride dropwise. After all the addition, warm up to room temperature, and add triethylamine as an acid-binding agent with an addition amount of 2.5% of the mass of allylsulfonyl chloride. Stir at room temperature for 16 h. After the reaction is completed, remove the solvent by vacuum distillation to obtain activated magnesium hydroxide particles; Step 3, surface modification treatment: Add 10 g of activated magnesium hydroxide particles to 300 mL of 50 wt% ethanol aqueous solution. Pass nitrogen as a protective gas, heat up to 80 °C, then gradually add 8.4 g of hydroxypropyl vinyl ether within half an hour, and then add 5 wt% ammonium persulfate solution dropwise within half an hour. The addition amount of ammonium persulfate is 10% of the mass of hydroxypropyl vinyl ether. Keep stirring at a constant temperature for 6 h. After the reaction is completed, naturally cool to room temperature. First, perform vacuum drying, then place it in a dialysis bag with a molecular weight cut-off MWCO of 5000 Da, and perform dialysis purification in pure water for 72 h. Then perform vacuum drying again to obtain modified magnesium hydroxide.

[0028] Example 4 A preparation method of modified magnesium hydroxide, comprising the following steps: Step 1, surface amino-functionalization treatment: Mix 10 g of 50-μm magnesium hydroxide particles with 150 mL of 60 wt% ethanol aqueous solution. First, stir evenly at room temperature, then add 4 g of γ-aminopropyltriethoxysilane (A-1100). Heat up to reflux in a heating device and continuously stir for 3 h. After that, perform suction filtration, washing, and drying to obtain amino-functionalized magnesium hydroxide particles; Step 2, surface activation treatment: Add 10 g of amino-functionalized magnesium hydroxide particles to 150 mL of tetrahydrofuran. Disperse evenly in an ice-water bath, then gradually add 3.6 g of allylsulfonyl chloride dropwise. After all the addition, warm up to room temperature, and add triethylamine as an acid-binding agent with an addition amount of 1.5% of the mass of allylsulfonyl chloride. Stir at room temperature for 12 h. After the reaction is completed, remove the solvent by vacuum distillation to obtain activated magnesium hydroxide particles; Step 3, surface modification treatment: 10 g of activated magnesium hydroxide particles were added to 200 mL of 20 wt % ethanol aqueous solution, nitrogen was introduced as a protective gas, the temperature was raised to 70° C., and then 5.5 g of hydroxypropyl vinyl ether was gradually added within half an hour, and then 2 wt % of ammonium persulfate solution was dropwise added within half an hour, wherein the amount of ammonium persulfate added was 3% of the mass of hydroxypropyl vinyl ether. The mixture was kept warm and stirred for 5 h. After the reaction was completed, the mixture was naturally cooled to room temperature, vacuum dried, and then placed in a dialysis bag with a molecular weight cutoff of 4000 Da. The mixture was dialyzed and purified in pure water for 60 h, and vacuum dried again to obtain modified magnesium hydroxide.

[0029] Comparative Example 1 A magnesium hydroxide is unmodified magnesium hydroxide particles (50 μm).

[0030] Comparative Example 2 A modified magnesium hydroxide is prepared by using amination magnesium hydroxide particles in the same manner as step 1 of Example 1.

[0031] Comparative Example 3 A modified magnesium hydroxide is prepared by using activated magnesium hydroxide particles in the same manner as steps 1 and 2 of Example 1.

[0032] Application Example 1 A highly filled material, calculated by weight, comprising: 100 parts of ethylene-vinyl acetate copolymer, 30 parts of polyethylene, 200 parts of filler, 16 parts of dioctyl phthalate, 5 parts of ethylene bisstearamide and 1 part of antioxidant 1076.

[0033] Application Example 2 A highly filled material, calculated by weight, comprising: 90 parts of ethylene-vinyl acetate copolymer, 20 parts of polyurethane, 30 parts of polystyrene resin, 150 parts of filler, 15 parts of dioctyl phthalate, 6 parts of zinc stearate and 1.5 parts of antioxidant 1010.

[0034] Application Example 3 A highly filled material, calculated by weight, comprising: 80 parts of ethylene-vinyl acetate copolymer, 25 parts of nylon 66, 5 parts of POE-G-MAH, 120 parts of filler, 10 parts of dioctyl phthalate, 4 parts of stearic acid and 1.2 parts of antioxidant 1098.

[0035] Experimental testing In the present invention, the modified magnesium hydroxide (or magnesium hydroxide) obtained in the best embodiment (Example 1) and comparative examples 1-3 are used as fillers in Application Example 1 to obtain different high-filling materials, which are numbered.

[0036] In Application Example 1: The VA content in the ethylene-vinyl acetate copolymer is 18%, and the melt index is 3.2 g / 10 min (190 °C / 2.16 kg); the density of polyethylene is 0.925 g / cm 3 , and the melt index is 20 g / 10 min (190 °C / 2.16 kg).

[0037] Then, the properties of different highly filled materials were tested, and the results are shown in Table 1.

[0038] Table 1 Filling properties of the magnesium hydroxide filled materials obtained in Example 1 and Comparative Examples 1-3

[0039] In Table 1, the detection reference standards for tensile strength and elongation at break are GB / T 1040.1-2018, the detection reference standard for brittle temperature by impact method is GB / T 5470-2008, the detection reference standard for smoke density is GB / T 8627-2007, and the detection reference standard for the flame retardant rating (UL-94) is the vertical burning method of ANSI / UL-94-2009.

[0040] It can be seen from Table 1 that compared with Comparative Examples 1-3, when the modified magnesium hydroxide prepared in Example 1 of the present invention is used as a filler in Application Example 1, it has more excellent performance in terms of mechanical strength and impact resistance, and also performs better in terms of the smoke density rating (SDR). Generally speaking, the modified magnesium hydroxide for highly filled materials prepared in Example 1 of the present invention, when applied to polymer materials, has excellent flame retardant filling properties. Compared with traditional magnesium hydroxide fillers, it not only improves the flame retardancy of polymer materials, but also significantly improves their mechanical strength and impact resistance.

[0041] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing modified magnesium hydroxide for high-filling materials, characterized in that: The following steps are involved: Step 1, surface amination treatment: The magnesium hydroxide particles and the ethanol aqueous solution are mixed, stirred evenly at room temperature, and then an aminosilane coupling agent is added, and the temperature is raised to reflux in a heating device, and stirring is continued for 2-6 hours, and then filtered, washed and dried to obtain the aminated magnesium hydroxide particles; Step 2, surface activation treatment: Add the aminated magnesium hydroxide particles into tetrahydrofuran, disperse them evenly in an ice-water bath, then gradually add allyl sulfonyl chloride dropwise, warm the mixture to room temperature after all the addition, add triethylamine dropwise as an acid-binding agent, stir at room temperature for 8-16 hours, and after the reaction is completed, remove the solvent by distillation under reduced pressure to obtain activated magnesium hydroxide particles; Step 3, surface modification: Add activated magnesium hydroxide particles into an aqueous solution of ethanol, introduce nitrogen as a protective gas, heat to 50-80°C, then gradually add hydroxypropyl vinyl ether within half an hour, then drop an initiator within half an hour, keep warm and stir for 3-6 hours, after the reaction is completed, cool and dry, then dialysis and purification treatment, and dry again to obtain modified magnesium hydroxide; the initiator is 1%-5% by mass of ammonium persulfate solution, and the actual amount of ammonium persulfate added is 1%-10% of the mass of hydroxypropyl vinyl ether.

2. The method for preparing a modified magnesium hydroxide for high-filling materials according to claim 1, characterized in that: In step 1, the particle size of the magnesium hydroxide particles is 1-100 μm; the mass fraction of the ethanol aqueous solution is 30%-80%, and the aminosilane coupling agent is γ-aminopropyltriethoxysilane or γ-aminopropyltrimethoxysilane.

3. The method for preparing a modified magnesium hydroxide for high-filling materials according to claim 1, characterized in that: In the step 1, the dosage ratio of the magnesium hydroxide particles, the aminosilane coupling agent and the ethanol aqueous solution is 10 g:(1-5) g:(100-200) mL.

4. The method for preparing a modified magnesium hydroxide for high-filling materials according to claim 1, characterized in that: In the step 2, the usage ratio of the amidated magnesium hydroxide particles, allyl sulfonyl chloride and tetrahydrofuran is 10 g:(2.8-5.6) g:(100-200) mL; and the amount of the acid binding agent added is 0.5%-2.5% of the mass of the allyl sulfonyl chloride.

5. The method for preparing a modified magnesium hydroxide for high-filling materials according to claim 1, characterized in that: In the step 3, the mass fraction of the ethanol aqueous solution is 10%-50%, and the amount ratio of the activated magnesium hydroxide particles, hydroxypropyl vinyl ether and the ethanol aqueous solution is 10g:(4.2-8.4)g:(100-300)mL.

6. The method for preparing a modified magnesium hydroxide for high-filling materials according to claim 1, characterized in that: In step 3, the molecular weight cutoff (MWCO) of the dialysis bag is 3000-5000Da, and the dialysis treatment time is 48-72h.

7. A modified magnesium hydroxide, characterized in that The modified magnesium hydroxide is prepared by the preparation method described in any one of claims 1 to 6.

8. Use of the modified magnesium hydroxide according to claim 7 as a flame retardant filling material in polymer materials.

9. The use of a modified magnesium hydroxide as a flame retardant filler in a polymer material according to claim 8, characterized in that: The polymer material is at least one of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyimide, nylon, polylactic acid, polyetheretherketone, styrene-butadiene rubber, chloroprene rubber, fluororubber, and ethylene-vinyl acetate copolymer.

10. The use of modified magnesium hydroxide as a flame retardant filler in polymer materials according to claim 8, characterized in that: The added amount of the modified magnesium hydroxide is 30%-70% of the total mass of the polymer material.

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