A modified magnesium hydroxide for high-filled materials and its preparation method

Abstract

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. The preparation method of the modified magnesium hydroxide comprises the following steps: Step 1, surface amination treatment of magnesium hydroxide particles; Step 2, reacting the aminated magnesium hydroxide particles with allyl sulfonyl chloride to obtain activated magnesium hydroxide particles; Step 3, reacting the activated magnesium hydroxide particles with hydroxypropyl vinyl ether to obtain modified magnesium hydroxide. The modified magnesium hydroxide for high-filled materials prepared by the present invention has excellent flame retardant filling properties when applied to polymer materials. Compared with traditional magnesium hydroxide fillers, it not only improves the flame retardancy of polymer materials, but also significantly enhances their mechanical strength and impact resistance.

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 the processability and functionality of materials while achieving high proportion 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 disperse uniformly in polymers, resulting in weak binding force and poor compatibility with polymers. Therefore, surface modification of magnesium hydroxide to improve its compatibility with polymers is very important.

[0004] Currently, the most commonly used method for modifying magnesium hydroxide is the surface modification method. The modifiers used for 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 be applied to the industrial surface modification of magnesium hydroxide. In addition, although silane coupling agents and anionic surfactants can be applied to 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, it will cause a decrease in the mechanical properties of polymer products. 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:

[0007] In the first aspect, the present invention provides a preparation method for a modified magnesium hydroxide for high-filled materials, comprising the following steps:

[0008] Step 1, surface amination treatment:

[0009] Mix magnesium hydroxide particles and an aqueous solution of ethanol, stir well at room temperature first, then add an amino-silane coupling agent, heat up to reflux in a heating device, continuously stir for 2 - 6 h, and then obtain amino-functionalized magnesium hydroxide particles through suction filtration, washing, and drying;

[0010] Step 2, surface activation treatment:

[0011] Add the amino-functionalized magnesium hydroxide particles into tetrahydrofuran, disperse evenly in an ice-water bath, then gradually dropwise add allyl sulfonyl chloride. After all the addition, heat up to room temperature, dropwise add triethylamine as an acid-binding agent, and stir at room temperature for 8 - 16 h. After the reaction ends, remove the solvent by vacuum distillation to obtain activated magnesium hydroxide particles;

[0012] Step 3, surface modification treatment:

[0013] 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 dropwise add an initiator within half an hour, keep warm and stir for 3 - 6 h. After the reaction ends, cool and dry, then carry out dialysis purification treatment, and dry again to obtain modified magnesium hydroxide.

[0014] Preferably, in the said step 1, the particle size of the magnesium hydroxide particles is 1 - 100 μm.

[0015] 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).

[0016] 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.

[0017] Preferably, in the said step 2, the dosage ratio of the amino-functionalized magnesium hydroxide particles, allyl sulfonyl chloride, and tetrahydrofuran is 10 g : (2.8 - 5.6) g : (100 - 200) mL.

[0018] 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.

[0019] 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.

[0020] Preferably, in the 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.

[0021] Preferably, in the step 3, the dialysis bag for dialysis has a molecular weight cut-off MWCO of 3000 - 5000 Da, and the dialysis treatment time is 48 - 72 h.

[0022] In the second aspect, the present invention provides a modified magnesium hydroxide prepared by the above preparation method.

[0023] In the third aspect, the present invention provides a modified magnesium hydroxide for use as a flame retardant filler for polymer materials.

[0024] 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).

[0025] Preferably, the addition amount of the flame retardant filler is 30% - 70% of the total mass of the polymer material.

[0026] The beneficial effects of the present invention are as follows:

[0027] 1. The present invention prepares a modified magnesium hydroxide for high-fill materials, which has excellent flame retardant filling properties when applied to polymer materials. Compared with traditional magnesium hydroxide fillers, it not only improves the flame retardancy of polymer materials, but also significantly enhances their mechanical strength and impact resistance.

[0028] 2. The process for preparing the modified magnesium hydroxide in the present invention includes: first, subjecting magnesium hydroxide particles to amination treatment, then undergoing a sulfonyl chloride - amino binding reaction with allyl sulfonyl chloride containing an unsaturated double bond to obtain activated magnesium hydroxide particles; and then undergoing a double bond polymerization crosslinking reaction with hydroxypropyl vinyl ether also containing an unsaturated bond to finally obtain the modified magnesium hydroxide.

[0029] 3. The surface of the modified magnesium hydroxide prepared in the present invention is coated with a network crosslinked polymer structure, and this polymer structure contains groups such as hydroxyl, ether, 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. Specific Embodiments

[0030] The technical solution of the present invention will be 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 the insertion of other method steps 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 each method step are only convenient tools for identifying each method step, rather than limiting the arrangement order of each method step or the scope in which the present invention can be implemented. The change or adjustment of their relative relationship, without substantial change in technical content, should also be regarded as the scope in which the present invention can be implemented.

[0031] To better understand the above technical solution, 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 described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0032] The present invention will be further described below in conjunction with the following embodiments.

[0033] Example 1

[0034] A preparation method of modified magnesium hydroxide includes the following steps:

[0035] Step 1, surface amination treatment:

[0036] 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 obtain aminated magnesium hydroxide particles through suction filtration, washing and drying.

[0037] Step 2, surface activation treatment:

[0038] Add 10 g of aminated magnesium hydroxide particles into 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, raise the temperature 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.

[0039] Step 3, surface modification treatment:

[0040] Add 10 g of activated magnesium hydroxide particles into 200 mL of 30 wt% ethanol aqueous solution, introduce nitrogen as the protective gas, heat up to 50 - 80 °C, then gradually add 6.3 g of hydroxypropyl vinyl ether within half an hour, and then dropwise add 3 wt% ammonium persulfate solution within half an hour. The addition amount of ammonium persulfate is 5% of the mass of hydroxypropyl vinyl ether. Keep stirring at a constant temperature for 4 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 4000 Da, and carry out dialysis purification treatment in pure water for 60 h, and then perform vacuum drying again to obtain modified magnesium hydroxide.

[0041] Example 2

[0042] A preparation method of modified magnesium hydroxide, comprising the following steps:

[0043] Step 1, surface amination treatment:

[0044] Mix 10 g of 50 - μm magnesium hydroxide particles and 100 mL of 30 wt% ethanol aqueous solution, first stir evenly at room temperature, then add 1 g of γ-aminopropyltriethoxysilane (A - 1100), heat up to reflux in a heating device, keep stirring for 2 h, and then obtain aminated magnesium hydroxide particles through suction filtration, washing and drying.

[0045] Step 2, surface activation treatment:

[0046] Add 10 g of aminated magnesium hydroxide particles into 100 mL of tetrahydrofuran, disperse evenly in an ice - water bath, then gradually dropwise add 2.8 g of allyl sulfonyl chloride. After all the addition, heat up to room temperature, dropwise add triethylamine as an acid - binding agent, and the addition amount is 0.5% of the mass of allyl sulfonyl chloride. Stir at room temperature for 8 h. After the reaction is completed, remove the solvent by vacuum distillation to obtain activated magnesium hydroxide particles.

[0047] Step 3, surface modification treatment:

[0048] Add 10 g of activated magnesium hydroxide particles into 100 mL of 10 wt% ethanol aqueous solution, introduce nitrogen as the protective gas, heat up to 50 °C, then gradually add 4.2 g of hydroxypropyl vinyl ether within half an hour, and then dropwise add 1 wt% ammonium persulfate solution within half an hour. The addition amount of ammonium persulfate is 1% of the mass of hydroxypropyl vinyl ether. Keep stirring at a constant temperature for 3 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 3000 Da, and carry out dialysis purification treatment in pure water for 48 h, and then perform vacuum drying again to obtain modified magnesium hydroxide.

[0049] Example 3

[0050] A preparation method of modified magnesium hydroxide, comprising the following steps:

[0051] Step 1, surface amination treatment:

[0052] Mix 10 g of 50-μm magnesium hydroxide particles and 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, continuously stir for 6 h, and then obtain aminated magnesium hydroxide particles through suction filtration, washing and drying;

[0053] Step 2, surface activation treatment:

[0054] Add 10 g of aminated magnesium hydroxide particles into 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, raise the temperature to room temperature, add triethylamine as an acid-binding agent, and the addition amount is 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;

[0055] Step 3, surface modification treatment:

[0056] Add 10 g of activated magnesium hydroxide particles into 300 mL of 50 wt% ethanol aqueous solution, introduce 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 a 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 treatment in pure water for 72 h, and then perform vacuum drying again to obtain modified magnesium hydroxide.

[0057] Example 4

[0058] A preparation method of modified magnesium hydroxide, comprising the following steps:

[0059] Step 1, surface amination treatment:

[0060] 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 4 g of γ-aminopropyltriethoxysilane (A-1100), heat up to reflux in a heating device, continuously stir for 3 h, and then obtain aminated magnesium hydroxide particles through suction filtration, washing and drying;

[0061] Step 2, surface activation treatment:

[0062] 10 g of aminated magnesium hydroxide particles were added to 150 mL of tetrahydrofuran and dispersed evenly in an ice-water bath. 3.6 g of allylsulfonyl chloride was then gradually added dropwise. After all the addition was complete, the temperature was raised to room temperature. Triethylamine was added dropwise as an acid-binding agent in an amount of 1.5% of the mass of allylsulfonyl chloride. The mixture was stirred at room temperature for 12 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure to obtain activated magnesium hydroxide particles.

[0063] Step 3, surface modification:

[0064] 10 g of activated magnesium hydroxide particles were added to 200 mL of a 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 a 2 wt % ammonium persulfate solution was added dropwise within half an hour, wherein the amount of ammonium persulfate added was 3% of the mass of hydroxypropyl vinyl ether. The mixture was stirred for 5 h. After the reaction was completed, it was naturally cooled to room temperature, vacuum dried, and then placed in a dialysis bag with a molecular weight cutoff (MWCO) of 4000 Da. It was dialyzed and purified in pure water for 60 h and vacuum dried again to obtain modified magnesium hydroxide.

[0065] Comparative Example 1

[0066] A magnesium hydroxide, which is unmodified magnesium hydroxide particles (50 μm).

[0067] Comparative Example 2

[0068] A modified magnesium hydroxide is prepared by using amination magnesium hydroxide particles in the same manner as step 1 of Example 1.

[0069] Comparative Example 3

[0070] A modified magnesium hydroxide is prepared by using activated magnesium hydroxide particles in the same manner as steps 1 and 2 of Example 1.

[0071] Application Example 1

[0072] A highly filled material, calculated by weight, comprising:

[0073] 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.

[0074] Application Example 2

[0075] A highly filled material, calculated by weight, comprising:

[0076] 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.

[0077] Application Example 3

[0078] A highly filled material, calculated by weight, comprising:

[0079] 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.

[0080] Experimental testing

[0081] In the present invention, the modified magnesium hydroxide (or magnesium hydroxide) obtained in the best embodiment (Example 1) and comparative examples 1-3 are respectively used as fillers in Application Example 1 to obtain different high-filling materials, which are numbered.

[0082] In Application Example 1, the VA content of ethylene-vinyl acetate copolymer is 18%, the melt index is 3.2g / 10min (190℃ / 2.16kg); the density of polyethylene is 0.925g / cm 3 , the melt index is 20g / 10min (190℃ / 2.16kg).

[0083] Then the performance of different high-filling materials was tested, and the results are shown in Table 1.

[0084] Table 1 Filling properties of magnesium hydroxide filling materials obtained in Example 1 and Comparative Examples 1-3

[0085]

[0086] In Table 1, the tensile strength and elongation at break test reference standard GB / T 1040.1-2018, the impact brittle temperature test reference standard GB / T 5470-2008, the smoke density test reference standard GB / T 8627-2007, and the flame retardant grade (UL-94) test reference standard ANSI / UL-94-2009 vertical combustion method.

[0087] As can be seen from Table 1, when the modified magnesium hydroxide prepared in Example 1 of the present invention is used as a filler in Application Example 1, it shows 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, when the modified magnesium hydroxide for high-filled materials prepared in Example 1 of the present invention is 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 enhances their mechanical strength and impact resistance.

[0088] 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 limitations of 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: Mixing magnesium hydroxide particles and an aqueous solution of ethanol, stirring uniformly at room temperature, then adding an aminosilane coupling agent, heating to reflux in a heating device, stirring continuously for 2-6 hours, and then filtering, washing, and drying to obtain aminated magnesium hydroxide particles; Step 2, surface activation treatment: Add the aminated magnesium hydroxide particles to tetrahydrofuran and disperse them evenly in an ice-water bath. Then gradually add allylsulfonyl chloride dropwise. After all the addition is complete, warm the mixture to room temperature. Then add triethylamine dropwise as an acid-binding agent. Stir at room temperature for 8-16 hours. After the reaction is complete, remove the solvent by distillation under reduced pressure to obtain activated magnesium hydroxide particles. Step 3, surface modification: Activated magnesium hydroxide particles are added to an aqueous solution of ethanol, nitrogen is introduced as a protective gas, the temperature is raised to 50-80°C, and then hydroxypropyl vinyl ether is gradually added within half an hour, and then an initiator is added dropwise within half an hour, and the mixture is kept warm and stirred for 3-6 hours. After the reaction is completed, the mixture is cooled and dried, and then subjected to dialysis purification treatment and dried again to obtain modified magnesium hydroxide; the initiator is a 1%-5% by mass ammonium persulfate solution, and the actual amount of ammonium persulfate added is 1%-10% of the mass of the hydroxypropyl vinyl ether.

2. The method for preparing a modified magnesium hydroxide for high-filling materials according to claim 1, wherein: 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, wherein: In the step 1, the 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, wherein: In step 2, the usage ratio of the amidated magnesium hydroxide particles, allylsulfonyl 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 allylsulfonyl chloride.

5. The method for preparing a modified magnesium hydroxide for high-filling materials according to claim 1, wherein: In 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 3000-5000 Da, and the dialysis treatment time is 48-72 h.

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

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

9. 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. Use of the 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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