Si-P-N ternary hybrid flame retardant and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a Si-P-N ternary hybrid flame retardant and a preparation method thereof.The method comprises the steps that wollastonite, a silane coupling agent KH570, ethyl alcohol and water are mixed and react to obtain a dehydration reaction product, then organic silicon resin and acetic acid are added into the dehydration reaction product, and a condensation polymerization reaction product is obtained after a reaction; the preparation method comprises the following steps: adding melamine and triphenyl phosphate into a solvent, reacting to obtain a polymer, mixing a polycondensation reaction product with the polymer, reacting to obtain an addition reaction product, adding a silane coupling agent KH570 into the addition reaction product, reacting to obtain a final reaction product, and drying the final reaction product to remove the solvent, thereby obtaining the Si-P-N ternary hybrid flame retardant. Nitrogen in the melamine, phosphorus in the triphenyl phosphate and silicon in the wollastonite fiber play a synergistic flame-retardant role, so that the flame-retardant property of the material is improved; the silane coupling agent KH570 is added twice, so that the interfacial compatibility is improved, and the mechanical properties of the material are not influenced.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a Si-PN ternary hybrid flame retardant and a preparation method thereof. Background Art

[0002] At present, the mainstream technology in the field of non-metallic materials is to apply high-quality or processed and purified wollastonite ore powder to chemical materials such as plastics, rubber, and paint to improve the flame retardancy and mechanical properties of these chemical materials. However, due to the limitations of the physical and chemical properties of wollastonite ore powder itself, the improvement of flame retardancy and mechanical properties is limited.

[0003] The invention patent with application number 201611153662.8 discloses a wollastonite powder reinforced thermoplastic elastomer data cable sheath material and its preparation method, in which wollastonite powder is treated with a silane coupling agent and then added to low-density polyethylene, and then dispersed in a blend matrix of stearic acid-modified SEBS and polypropylene to improve the strength, rigidity and heat resistance of the product. Since it is a single silicon element flame retardant, the flame retardant effect is poor.

[0004] Application No. 201711200023.7 discloses a method for preparing a polyurethane material, in which a variety of halogen-free flame retardants, such as phosphorus-based flame retardants, nitrogen-based flame retardants, carbon-forming agents, and flame retardant synergists, are added to thermoplastic polyurethane resin. Although a good flame retardant effect can be guaranteed, the poor compatibility of these flame retardants with the polyurethane resin matrix has a significant impact on the mechanical properties of the product, and it cannot be widely used and is only used in some specific scenarios.

[0005] Therefore, how to improve the flame retardant properties while ensuring that the mechanical properties are not affected is a problem that needs to be solved urgently. Summary of the invention

[0006] The purpose of the present invention is to provide a Si-PN ternary hybrid flame retardant having both high flame retardancy and high mechanical properties and a preparation method thereof in view of the above problems existing in the prior art.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a method for preparing a Si-PN ternary hybrid flame retardant, the preparation method comprising:

[0009] S1, mixing wollastonite, silane coupling agent KH570, ethanol and water to obtain a dehydration reaction product, and then adding silicone resin and acetic acid to the dehydration reaction product to obtain a polycondensation reaction product;

[0010] S2, adding melamine and triphenyl phosphate to the solvent to react to obtain a polymer;

[0011] S3, mixing the polycondensation reaction product with the polymer to obtain an addition reaction product, and then adding a silane coupling agent KH570 to the addition reaction product to obtain a final reaction product;

[0012] S4. Drying the final reaction product to remove the solvent to obtain a Si-PN ternary hybrid flame retardant.

[0013] The weight ratio of the wollastonite, the silane coupling agent KH570 in S1, the silicone resin, melamine, triphenyl phosphate, and the silane coupling agent KH570 in S3 is 800g:1-1.2g:25-75g:75-125g:25-40g:10-12g.

[0014] The organic silicone resin is phenyl vinyl silicone resin.

[0015] The solvent is dimethyl sulfoxide (DMSO).

[0016] In a second aspect, the present invention provides a Si-PN ternary hybrid flame retardant, wherein the Si-PN ternary hybrid flame retardant is prepared by the aforementioned preparation method.

[0017] In a third aspect, the present invention provides a resin composition, wherein the resin composition is obtained by mixing a polypropylene resin with the aforementioned Si-PN ternary hybrid flame retardant and then melt-extruding the mixture using a twin-screw extruder.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The invention discloses a method for preparing a Si-PN ternary hybrid flame retardant. The method comprises the following steps: firstly mixing wollastonite, silane coupling agent KH570, ethanol and water to obtain a dehydration reaction product, then adding silicone resin and acetic acid to the dehydration reaction product to obtain a polycondensation reaction product; then adding melamine and triphenyl phosphate to a solvent to obtain a polymer, mixing the polycondensation reaction product with the polymer to obtain an addition reaction product, then adding silane coupling agent KH570 to the addition reaction product to obtain a final reaction product, and drying the final reaction product to remove the solvent to obtain a Si-PN ternary hybrid flame retardant. On the one hand, the invention introduces melamine and triphenyl phosphate, and the nitrogen in melamine, the phosphorus in triphenyl phosphate and the silicon in wollastonite fiber play a synergistic flame retardant role to improve the flame retardant performance of the material; on the other hand, by adding the silane coupling agent KH570 twice, the interfacial compatibility between the flame retardant and the silicone resin is improved, thereby ensuring that the mechanical properties of the material are not affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the reaction principle diagram of S1 in Example 1.

[0021] Figure 2 This is the reaction principle diagram of S2 in Example 1.

[0022] Figure 3 This is the reaction principle diagram of S4 in Example 1.

[0023] Figure 4 This is the reaction principle diagram of S5 in Example 1. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with specific implementations and drawings.

[0025] A method for preparing a Si-PN ternary hybrid flame retardant, the preparation method comprising:

[0026] S1, mixing wollastonite, silane coupling agent KH570, ethanol and water to obtain a reaction product A, and then adding silicone resin and acetic acid to the reaction product A to obtain a reaction product B;

[0027] S2, adding melamine and triphenyl phosphate to the solvent to react to obtain a reaction product C;

[0028] S3, mixing the reaction product B with the reaction product C to obtain a reaction product D, and then adding a silane coupling agent KH570 to the reaction product D to obtain a reaction product E;

[0029] S4. Dry the reaction product E to remove the solvent, and obtain a Si-PN ternary hybrid flame retardant.

[0030] The weight ratio of the wollastonite, the silane coupling agent KH570 in S1, the silicone resin, melamine, triphenyl phosphate, and the silane coupling agent KH570 in S3 is 800g:1-1.2g:25-75g:75-125g:25-40g:10-12g.

[0031] The organic silicone resin is phenyl vinyl silicone resin.

[0032] The solvent is dimethyl sulfoxide (DMSO).

[0033] A Si-PN ternary hybrid flame retardant is prepared by the above-mentioned preparation method.

[0034] A resin composition is obtained by mixing polypropylene resin and the aforementioned Si-PN ternary hybrid flame retardant and then melt-extruding them using a twin-screw extruder.

[0035] The principle of the present invention is described as follows:

[0036] Silane coupling agent KH570 has high content of methoxy and vinyl groups, and the methoxy group is easily hydrolyzed. The present invention introduces silane coupling agent KH570 twice. The methoxyl group in the silane coupling agent KH570 introduced for the first time is hydrolyzed to form a hydroxyl group, which undergoes a dehydration reaction with the hydroxyl group on the surface of wollastonite to form a siloxane bond. The high content of siloxane bonds can increase the decomposition temperature of the material, thereby improving the heat resistance of the material. In addition, after adding melamine and triphenyl phosphate, the vinyl group in the silane coupling agent KH570 introduced for the first time is opened, and the vinyl group forms a chemical bond with melamine and triphenyl phosphate through an addition reaction, thereby grafting melamine and triphenyl phosphate on the surface of wollastonite, which not only reduces the specific surface area of ​​wollastonite powder, but also reduces the contact surface between wollastonite powder and resin, so that wollastonite powder and resin can be better compatible, and the mechanical strength of the material can be improved. In addition, nitrogen in melamine, phosphorus in triphenyl phosphate and silicon in wollastonite fiber play a synergistic flame retardant role, thereby improving the flame retardant performance of the material. The silane coupling agent KH570 introduced for the second time is coated on the surface of wollastonite, providing dispersibility for the Si-PN ternary hybrid flame retardant through vinyl, improving the interface between the Si-PN ternary hybrid flame retardant and the polypropylene resin, thereby ensuring that the mechanical properties of the resin composition are not affected.

[0037] Embodiment 1:

[0038] A method for preparing a Si-PN ternary hybrid flame retardant is carried out in the following steps:

[0039] S1. Place 800g of wollastonite and 1.2g of silane coupling agent KH570 in a high-speed stirrer and stir at high speed for 5min. Add 50mL of ethanol and 50mL of water, adjust the pH value to 4, and react at 80°C for 30min. The trimethoxy group in the silane coupling agent KH570 is hydrolyzed to form a hydroxyl group. The water or ethanol environment can accelerate the hydrolysis of the trimethoxy group. The hydroxyl group reacts with the hydroxyl group on the surface of wollastonite to form a siloxane bond, so that the wollastonite and the silane coupling agent KH570 are connected through the siloxane bond to obtain a dehydration reaction product. The reaction principle is as follows: Figure 1 As shown;

[0040] S2. Add 50g of silicone resin and 10g of acetic acid to the dehydration reaction product. Use acetic acid as a catalyst to cause the dehydration reaction product to undergo polycondensation and chain growth with the silicone resin through the vinyl provided by the silane coupling agent KH570 to obtain a polycondensation product. Since the silicone resin is a phenyl vinyl silicone resin, which contains phenyl groups and silicon-oxygen bonds, the energy required to destroy the benzene ring and the silicon-oxygen bond is higher. Therefore, grafting the phenyl vinyl silicone resin onto wollastonite can further improve the high temperature resistance of the material. The reaction principle is as follows: Figure 2 As shown;

[0041] S3, pre-treating melamine and triphenyl phosphate, wherein the pre-treatment refers to removing water at high temperature and then crushing and grinding;

[0042] S4, 100g of pretreated melamine, 33g of triphenyl phosphate and 50mL of solvent were mixed, and stirred at 150°C for 2h. Melamine and triphenyl phosphate underwent polymerization and cross-linking reaction in the solvent to obtain a polymer. After the reaction, the mixture was dried overnight at 180°C in a vacuum. The molar ratio of melamine to triphenyl phosphate was 3:1, and the solvent was dimethyl sulfoxide (DMSO). The reaction principle is as follows: Figure 3 As shown, by first reacting melamine with triphenyl phosphate to form a polymer and then grafting the polymer, the ratio of phosphorus to nitrogen in the final Si-PN ternary hybrid flame retardant is fixed at an optimal ratio;

[0043] S5. The polycondensation reaction product and the polymer are placed in a high-speed stirrer and stirred at high speed for 2 hours. The vinyl group in the silane coupling agent KH570 will open and form chemical bonds with melamine and triphenyl phosphate through addition reaction. Melamine and triphenyl phosphate are grafted on the surface of wollastonite to reduce the specific surface area of ​​wollastonite powder, thereby reducing the contact area between the powder and the resin, improving the mechanical strength, and obtaining the addition reaction product. The reaction principle is as follows: Figure 4 As shown; 10 g of silane coupling agent KH570 is continued to be added, and the silane coupling agent KH570 is coated on the surface of the addition reaction product by high-speed stirring to obtain the final reaction product;

[0044] S6. Drying the final reaction product to remove the solvent to obtain a Si-PN ternary hybrid flame retardant.

[0045] A method for preparing a resin composition, specifically comprising: mixing 100g of a prepared Si-PN ternary hybrid flame retardant and 4000g of a polypropylene resin, and then melt-extruding the mixture using a twin-screw extruder to obtain the resin composition; the melt-extrusion temperature is 180°C, the screw speed is 330r / min, and the screw aspect ratio is 40:1.

[0046] Since the silane coupling agent KH570 coated on the surface of the reaction product D can provide a large amount of vinyl, and the polypropylene resin also has a large amount of vinyl, after the Si-PN ternary hybrid flame retardant is added to the polypropylene resin as an auxiliary agent, according to the principle of similar compatibility, the two will have good compatibility, thereby providing higher dispersibility for the Si-PN ternary hybrid flame retardant.

[0047] Embodiment 2:

[0048] The difference from Example 1 is that:

[0049] In the preparation method of Si-PN ternary hybrid flame retardant, wollastonite 800g, silane coupling agent KH570 1g in S1, silicone resin 50g, melamine 100g, triphenyl phosphate 33g, silane coupling agent KH570 10g in S5;

[0050] In the preparation method of the resin composition, 100 g of Si-PN ternary hybrid flame retardant and 4000 g of polypropylene resin are used; the melt extrusion temperature is 250° C. and the screw speed is 420 r / min.

[0051] Embodiment 3:

[0052] The difference from Example 1 is that:

[0053] In the preparation method of Si-PN ternary hybrid flame retardant, wollastonite 800g, silane coupling agent KH570 1g in S1, silicone resin 25g, melamine 125g, triphenyl phosphate 40g, silane coupling agent KH570 10g in S5;

[0054] In the preparation method of the resin composition, 100 g of Si-PN ternary hybrid flame retardant and 4000 g of polypropylene resin are used; the melt extrusion temperature is 220° C. and the screw speed is 380 r / min.

[0055] Embodiment 4:

[0056] The difference from Example 1 is that:

[0057] In the preparation method of Si-PN ternary hybrid flame retardant, wollastonite 800g, silane coupling agent KH570 1g in S1, silicone resin 75g, melamine 75g, triphenyl phosphate 25g, silane coupling agent KH570 12g in S5;

[0058] In the preparation method of the resin composition, 100 g of Si-PN ternary hybrid flame retardant and 4000 g of polypropylene resin are used; the melt extrusion temperature is 195° C. and the screw speed is 400 r / min.

[0059] Comparative Example 1:

[0060] 800 g of wollastonite, 11.2 g of silane coupling agent KH570, 100 g of melamine, and 33 g of triphenyl phosphate were blended, and then mixed with 4000 g of polypropylene resin, and melt-extruded using a twin-screw extruder to obtain a resin composition; the melt extrusion temperature, screw speed, and screw aspect ratio of the twin-screw extruder were the same as those in Example 1.

[0061] Comparative Example 2:

[0062] The difference from Example 1 is that in S5, the polycondensation reaction product is directly placed in a high-speed stirrer with the pretreated melamine and triphenyl phosphate for high-speed stirring for 2 hours.

[0063] Performance Verification:

[0064] The resin composition obtained in Example 1-4 was pressed at 220° C. and 10 MPa for 15 min to obtain a test piece with a length of 127 mm, a width of 10.7 mm, and a thickness of 4 mm. The test piece was subjected to a performance test; the performance test results are shown in Table 1.

[0065] Table 1 Performance test results of Examples 1-4

[0066]

[0067] As can be seen from Table 1, the flame retardants prepared in Examples 1-4 have significantly improved tensile strength, impact strength, and flexural strength compared to pure polypropylene resin and Comparative Example 1, and the flame retardant grade is improved to V-0, and the limiting oxygen index is improved to above 28. It can be seen that the flame retardant prepared in the present invention has better flame retardant properties, high temperature resistance, and mechanical properties, and the preparation process is simple, the cost is low, and the equipment requirements are low, and it can be widely used in the field of flame retardant, fireproof, and high temperature resistant materials.

Claims

1. A method for preparing a Si-PN ternary hybrid flame retardant, characterized in that: The preparation method comprises: S1, mixing wollastonite, silane coupling agent KH570, ethanol and water to obtain a dehydration reaction product, and then adding silicone resin and acetic acid to the dehydration reaction product to obtain a polycondensation reaction product; S2, adding melamine and triphenyl phosphate to the solvent to react to obtain a polymer; S3, mixing the polycondensation reaction product with the polymer to obtain an addition reaction product, and then adding a silane coupling agent KH570 to the addition reaction product to obtain a final reaction product; S4. Drying the final reaction product to remove the solvent to obtain a Si-PN ternary hybrid flame retardant.

2. The method for preparing a Si-PN ternary hybrid flame retardant according to claim 1, characterized in that: The weight ratio of the wollastonite, the silane coupling agent KH570 in S1, the silicone resin, melamine, triphenyl phosphate, and the silane coupling agent KH570 in S3 is 800g:1-1.2g:25-75g:75-125g:25-40g:10-12g.

3. The method for preparing a Si-PN ternary hybrid flame retardant according to claim 1, characterized in that: The organic silicone resin is phenyl vinyl silicone resin.

4. The method for preparing a Si-PN ternary hybrid flame retardant according to claim 1, characterized in that: The solvent is dimethyl sulfoxide (DMSO).

5. A Si-PN ternary hybrid flame retardant, characterized in that: The Si-PN ternary hybrid flame retardant is prepared by the preparation method described in any one of claims 1 to 3.

6. A resin composition, characterized in that: The resin composition is obtained by mixing polypropylene resin with the Si-PN ternary hybrid flame retardant described in any one of claims 1 to 4 and then melt-extruding the mixture using a twin-screw extruder.

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