Flame-retardant SEBS / silicone rubber composite material and preparation method thereof

Abstract

The invention relates to the field of preparation of high polymer materials, and particularly discloses a flame-retardant SEBS / silicone rubber composite material and a preparation method thereof. The flame-retardant SEBS / silicone rubber composite material is prepared from the following raw material components in parts by weight: 30 to 50 parts of SEBS; 20-40 parts of silicone rubber; 6-9 parts of a composite flame retardant; 6-9 parts of an inorganic flame-retardant filler; 4-8 parts of a diluent; 3-8 parts of a compatibilizer; 1-2 parts of a cross-linking agent; 0.5 to 2 parts of an antioxidant; the composite flame retardant is prepared from melamine, resorcinol and formaldehyde, and the inorganic flame-retardant filler comprises PEG (polyethylene glycol) modified magnesium hydroxide and hydrotalcite; the preparation method comprises the following steps: blending the raw materials, and carrying out melt extrusion to obtain the flame-retardant SEBS / silicone rubber composite material. The limit oxygen index of the composition is increased by 39.5% or above, the highest hardness change rate does not exceed 18.4%, and the composition has moderate hardness and excellent flame retardance.

Description

Technical Field

[0001] The present application relates to the technical field of polymer material preparation, and in particular to a flame retardant SEBS / silicone rubber composite material and a preparation method thereof. Background Art

[0002] SEBS (styrene-ethylene-butylene-styrene block copolymer) is a thermoplastic elastomer made by hydrogenating SBS (styrene-butadiene-styrene block copolymer). Its molecular structure consists of polystyrene as the hard segment and ethylene-butylene copolymer as the soft segment, forming a physically cross-linked network that combines the elasticity of rubber with the processing properties of plastic. Silicone rubber, on the other hand, is a polymer elastomer with a silicon-oxygen bond (-Si-O-) as its main chain, exhibiting excellent flexibility, temperature resistance, and processing stability. SEBS / silicone rubber composites are multifunctional materials formed by blending or compounding SEBS with silicone rubber, combining the thermoplastic processing advantages of SEBS with the flexibility of silicone rubber. SEBS / silicone rubber composites are widely used in a variety of fields, including medical devices (for medical pistons, stoppers, and gaskets), the automotive industry (for the preparation of wear-resistant materials, shock-absorbing components, and engine seals), and electronic appliances (for the preparation of injection molded parts).

[0003] As the use of SEBS / silicone rubber composites becomes more and more widespread, users have discovered that the overall flame retardancy of this material is relatively poor. It is easy to burn and continue to spread when encountering a fire source. This is because SEBS has poor flame retardancy, and when the two are compounded, a compatibilizer (such as EPDM) needs to be added, which also has poor flame retardancy. Therefore, although SEBS / silicone rubber composites have good thermoplastic processing advantages and flexibility, their flame retardancy needs to be improved.

[0004] Some researchers have proposed adding flame retardants (such as inorganic flame retardant fillers, phosphorus flame retardants and nitrogen-phosphorus flame retardants) to SEBS / silicone rubber composites to enhance their flame retardancy. However, flame retardants will significantly increase the hardness of SEBS / silicone rubber composites, seriously affecting their flexibility. Summary of the Invention

[0005] In order to solve the above technical problems, the present application provides a flame retardant SEBS / silicone rubber composite material and a preparation method thereof.

[0006] In the first aspect, the present application provides a flame-retardant SEBS / silicone rubber composite material, in which the raw materials used include the following components, by weight: 30-50 parts of SEBS; 20-40 parts of silicone rubber; 6-9 parts of a composite flame retardant; 6-9 parts of an inorganic flame retardant filler; 4-8 parts of a diluent; 3-8 parts of a compatibilizer; 1-2 parts of a cross-linking agent; and 0.5-2 parts of an antioxidant; the composite flame retardant is prepared from melamine, resorcinol, and formaldehyde, and the inorganic flame retardant filler includes PEG-modified magnesium hydroxide and hydrotalcite in a weight ratio of (35-40):(20:25).

[0007] By adopting the above-mentioned technical scheme, the present application utilizes melamine, resorcinol and formaldehyde to prepare a composite flame retardant, which has a high nitrogen content, and has good flame retardancy, high temperature resistance and ablation resistance. More importantly, it has good compatibility with silicone rubber and is relatively evenly and fully distributed in the silicone rubber matrix. Therefore, it can greatly improve the flame retardancy of the SEBS / silicone rubber composite material while reducing the amount of flame retardant added; the present application also adds an inorganic flame retardant filler, which can play a good synergistic role with the composite flame retardant, further improving the flame retardancy of the SEBS / silicone rubber composite material. At the same time, PEG-modified magnesium hydroxide has a lower particle size than ordinary magnesium hydroxide, and can be more fully dispersed inside the matrix, greatly improving the flame retardant effect while reducing the amount of flame retardant added. In summary, the flame retardant SEBS / silicone rubber composite material of the present application has a low amount of flame retardant added, but has a good flame retardant effect. Experimental data show that the limiting oxygen index of the flame retardant SEBS / silicone rubber composite material of the present application is increased by more than 39.5% compared to the ordinary SEBS / silicone rubber composite material without any flame retardant added, and the hardness change rate does not exceed 18.4%, which has both moderate hardness and excellent flame retardancy. The diluent of the specific embodiment of the present application is hexamethyldisiloxane, the compatibilizer is ethylene propylene diene monomer rubber, the crosslinker is tetrapropoxysilane, and the antioxidant is antioxidant 1010. The above substances are for illustrative purposes only. Those skilled in the art can replace different substances according to different needs in actual applications, and they cannot limit the scope of protection of the present application in turn.

[0008] Preferably, the raw materials used include the following components by weight: 35-45 parts of SEBS; 30 parts of silicone rubber; 7.5 parts of composite flame retardant; 7.5 parts of inorganic flame retardant filler; 6 parts of diluent; 4-6 parts of compatibilizer; 1.5 parts of crosslinking agent; and 1-1.5 parts of antioxidant.

[0009] By adopting the above technical solution, the present application adjusts the weight ratio of each raw material. On the basis of meeting the raw material components in the flame-retardant SEBS / silicone rubber composite material, the dosage is further optimized, which can better play the synergistic effect of each raw material, so that the composite material has moderate hardness and excellent flame retardancy, while maintaining good thermoplastic processing advantages and flexibility.

[0010] Preferably, the inorganic flame retardant filler comprises PEG-modified magnesium hydroxide and hydrotalcite in a weight ratio of 38:22.

[0011] By adopting the above technical solution, the present application combines PEG-modified magnesium hydroxide and hydrotalcite in the inorganic flame retardant filler in a specific weight ratio of 38:22, which can further optimize the synergistic effect with the composite flame retardant, thereby better improving the flame retardant properties of the flame retardant SEBS / silicone rubber composite material while reducing the amount of flame retardant added, and helping to maintain a moderate hardness of the material.

[0012] Preferably, the inorganic flame retardant filler further comprises red phosphorus, and the amount of red phosphorus used is 15-20 wt % of the total amount of the inorganic flame retardant filler.

[0013] By adopting the above technical solution, the present application adds a certain amount of red phosphorus to the inorganic flame retardant filler, which can better cooperate with other flame retardant substances, further improve the flame retardancy of SEBS / silicone rubber composite materials, and still maintain a good flame retardant effect at a low amount of flame retardant added, so that the material has both moderate hardness and excellent flame retardancy.

[0014] In the second aspect, the present application provides a method for preparing a flame-retardant SEBS / silicone rubber composite material, comprising the following steps: blending SEBS, silicone rubber, a composite flame retardant, an inorganic flame retardant filler, a diluent, a compatibilizer, a cross-linking agent and an antioxidant, and melt-extruding to obtain a flame-retardant SEBS / silicone rubber composite material, wherein the temperature of the melt extrusion is set to: the temperature of zone 1 is 140-160°C, the temperature of zone 2 is 160-180°C, the temperature of zone 3 is 180-200°C, and the temperature of zone 4 is 200-220°C.

[0015] By adopting the above technical solution, the present application first blends SEBS, silicone rubber, composite flame retardant, inorganic flame retardant filler, diluent, compatibilizer, cross-linking agent and antioxidant and then melt-extrudes them, and sets a specific melt extrusion temperature range to allow the raw materials to fully fuse and react to obtain a flame-retardant SEBS / silicone rubber composite material with moderate hardness and excellent flame retardancy. The limiting oxygen index of the composite material is increased by more than 39.5% compared with the ordinary SEBS / silicone rubber composite material without adding any flame retardant substances, and the hardness change rate does not exceed 18.4% at most; the composite flame retardant has a high nitrogen content, good flame retardancy and good compatibility with silicone rubber, which can improve the flame retardant ability of the composite material while reducing the amount of addition; the inorganic flame retardant filler and the composite flame retardant are coordinated, and the PEG-modified magnesium hydroxide has a low particle size and good dispersibility, which can further enhance the flame retardant effect.

[0016] Preferably, melamine, resorcinol and formaldehyde are mixed and reacted in a weight ratio of 20:(15-20):(22-24), and then placed at a temperature of 75-85°C for 2-2.5 hours, filtered, and the resulting solid is washed and dried to obtain a composite flame retardant.

[0017] Preferably, the weight ratio of melamine, resorcinol and formaldehyde is 20:17:23.

[0018] By adopting the above technical solution, the composite flame retardant prepared by the present application using melamine, resorcinol and formaldehyde in a specific weight ratio has a high nitrogen content, good flame retardancy, high temperature resistance and ablation resistance, and good compatibility with silicone rubber. It can be evenly and fully distributed in the silicone rubber matrix, and can greatly improve the flame retardant ability of the flame retardant SEBS / silicone rubber composite material while reducing the amount of flame retardant added.

[0019] Preferably, the PEG-modified magnesium hydroxide in the inorganic flame retardant filler is prepared by the following method: sodium hydroxide, magnesium nitrate and PEG6000 are blended and dispersed in water, reacted, filtered, the obtained solid is washed, and dried to obtain PEG-modified magnesium hydroxide, the concentration of magnesium nitrate in the system is controlled to be 0.4-0.8 mol / L, and the amount of PEG6000 is 2-5wt% of the total amount of sodium hydroxide and magnesium nitrate.

[0020] Preferably, the concentration of magnesium nitrate in the control system is 0.5 mol / L.

[0021] Preferably, the amount of PEG6000 is 4 wt% of the total amount of sodium hydroxide and magnesium nitrate.

[0022] By adopting the above technical solution, the magnesium hydroxide obtained by PEG modification in this application has a lower particle size, which can be more fully dispersed within the matrix. It can synergize with the composite flame retardant to significantly improve the flame retardancy of the SEBS / silicone rubber composite material while reducing the amount of flame retardant added, so that the material has both moderate hardness and excellent flame retardancy. This application also further reduces the particle size of the PEG-modified magnesium hydroxide by strictly controlling the concentration of magnesium nitrate and the amount of PEG6000 in the system, ensuring a more complete dispersion effect.

[0023] In summary, this application has the following beneficial technical effects: 1. The composite flame retardant of the present application has good compatibility with silicone rubber and is evenly and fully distributed in the silicone rubber matrix. It can significantly improve the flame retardancy of the SEBS / silicone rubber composite material while reducing the amount of flame retardant added. The inorganic flame retardant filler and the composite flame retardant are synergistically formulated to further enhance the flame retardancy of the SEBS / silicone rubber composite material. In addition, the PEG-modified magnesium hydroxide has a small particle size and can be more fully dispersed within the matrix, thereby reducing the amount of flame retardant added and improving the flame retardant effect. 2. The flame retardant SEBS / silicone rubber composite material of the present application has a low amount of flame retardant added, but has a good flame retardant effect. The limiting oxygen index is increased by more than 39.5% compared with the ordinary SEBS / silicone rubber composite material, and the maximum hardness change rate does not exceed 18.4%. It has both moderate hardness and excellent flame retardancy. DETAILED DESCRIPTION

[0024] Material Source Unless otherwise specified, the raw materials used in this application are all commercially available products, specifically: Hydrotalcite was purchased from Zhejiang Huate New Materials Co., Ltd. with a particle size of 200 mesh; Red phosphorus was purchased from Jiangsu Anget Group, with an active substance content of 40 wt%, and coated with ethylene-vinyl acetate copolymer; nano-montmorillonite was purchased from Zhejiang Huate New Materials Co., Ltd., with a particle size of ≤20 μm; Expanded graphite was purchased from Lingshou County Malin Mineral Products Processing Plant with a particle size of ≤30 μm.

[0025] The present application is further described in detail below with reference to preparation examples, embodiments and comparative examples.

[0026] Preparation Example 1.1 The preparation method of the composite flame retardant comprises the following steps: 15 g of resorcinol and 23.8 g of 37 wt% formaldehyde solution were dispersed in 50 mL of deionized water, stirred at room temperature and airtight conditions until the solution was clear, and set aside. Subsequently, 20 g of melamine and 35.7 g of 37 wt% formaldehyde solution were dispersed in 100 mL of deionized water, stirred in an 80°C water bath and airtight conditions until the solution was clear, and then quickly cooled to room temperature. The previously obtained solution was blended with this solution, and the volume was made up to 400 mL with deionized water. The solution was shaken until it was homogeneous, and the solution was placed in an oven at ℃ under airtight conditions for 2 h, filtered, and the obtained solid was washed and then placed in an electric blast oven at 80°C to dry for 48 h to obtain a composite flame retardant.

[0027] Preparation Example 1.2 The preparation method of the composite flame retardant comprises the following steps: 20 g of resorcinol and 25.9 g of 37 wt% formaldehyde solution were dispersed in 50 mL of deionized water, stirred at room temperature and airtight conditions until the solution was clear, and set aside. Subsequently, 20 g of melamine and 38.9 g of 37 wt% formaldehyde solution were dispersed in 100 mL of deionized water, stirred in an 80°C water bath and airtight conditions until the solution was clear, and then quickly cooled to room temperature. The previously obtained solution was blended with this solution, and the volume was made up to 400 mL with deionized water. The solution was shaken until it was homogeneous, and the solution was placed in an oven at ℃ under airtight conditions for 2 h, filtered, and the obtained solid was washed and then placed in an electric blast oven at 80°C to dry for 48 h to obtain a composite flame retardant.

[0028] Preparation Example 1.3 The preparation method of the composite flame retardant comprises the following steps: 17 g of resorcinol and 24.9 g of a 37 wt% formaldehyde solution were dispersed in 50 mL of deionized water, stirred at room temperature and airtight conditions until the solution was clear, and set aside. Subsequently, 20 g of melamine and 37.3 g of a 37 wt% formaldehyde solution were dispersed in 100 mL of deionized water, stirred in an 80°C water bath and airtight conditions until the solution was clear, and then quickly cooled to room temperature. The previously obtained solution was blended with this solution, and the volume was made up to 400 mL with deionized water. The solution was shaken until it was homogeneous, and the solution was placed in an oven at ℃ under airtight conditions for 2 h, filtered, and the obtained solid was washed and then placed in an electric blast oven at 80°C to dry for 48 h to obtain a composite flame retardant.

[0029] Preparation Example 2.1 The preparation method of PEG-modified magnesium hydroxide comprises the following steps: 300g of magnesium nitrate was dispersed in 2.5L of water, 23g of PEG6000 was added at a temperature of 60°C, and then stirring was started and the speed was controlled at 600r / min. 160g of sodium hydroxide was dispersed in 2.5L of water and added dropwise to the mixed solution of magnesium nitrate and PEG6000 for 30min. Then stirring was continued for 15min, filtered, and the filter cake was washed with water 4 times and with alcohol once, and then dried at a temperature of 120°C for 3h. After grinding, PEG-modified magnesium hydroxide with a particle size of about 0.3um was obtained.

[0030] Preparation Example 2.2 The preparation method of PEG-modified magnesium hydroxide comprises the following steps: 300 g of magnesium nitrate was dispersed in 1.25 L of water, 9.2 g of PEG6000 was added at a temperature of 60 ° C, and then stirring was started and the speed was controlled at 600 r / min. 160 g of sodium hydroxide was dispersed in 1.25 L of water and added dropwise to the mixed solution of magnesium nitrate and PEG6000 for 30 minutes. Then stirring was continued for 15 minutes, filtered, and the filter cake was washed with water 4 times and with alcohol once, and then dried at a temperature of 120 ° C for 3 hours. After grinding, PEG-modified magnesium hydroxide with a particle size of about 0.3 μm was obtained.

[0031] Preparation Example 2.3 The preparation method of PEG-modified magnesium hydroxide comprises the following steps: 300g of magnesium nitrate was dispersed in 2L of water, 18.4g of PEG6000 was added at a temperature of 60°C, and then stirring was started and the speed was controlled at 600r / min. 160g of sodium hydroxide was dispersed in 2L of water and added dropwise to the mixed solution of magnesium nitrate and PEG6000 for 30min. Then stirring was continued for 15min, filtered, and the filter cake was washed with water 4 times and with alcohol once, and then dried at a temperature of 120°C for 3h. After grinding, PEG-modified magnesium hydroxide with a particle size of about 0.2um was obtained.

[0032] Example 1.1 A method for preparing a flame retardant SEBS / silicone rubber composite material comprises the following steps: 500g SEBS, 200g silicone rubber, 60g of the composite flame retardant prepared in Preparation Example 1.1, 90g of inorganic flame retardant filler (52.5g of PEG-modified magnesium hydroxide prepared in Preparation Example 2.1 and 37.5g of hydrotalcite), 40g of hexamethyldisiloxane, 80g of EPDM rubber, 10g of tetrapropoxysilane and 20g of antioxidant 1010 were blended, stirred at a speed of 100r / min for 10min, and melt-extruded to obtain a flame-retardant SEBS / silicone rubber composite material. The melt extrusion temperature was set to 160°C for zone 1, 180°C for zone 2, 200°C for zone 3, and 220°C for zone 4.

[0033] Example 1.2 A method for preparing a flame retardant SEBS / silicone rubber composite material comprises the following steps: 300g SEBS, 400g silicone rubber, 90g of the composite flame retardant prepared in Preparation Example 1.2, 60g of inorganic flame retardant filler (40g of PEG-modified magnesium hydroxide prepared in Preparation Example 2.2 and 20g of hydrotalcite), 80g of hexamethyldisiloxane, 30g of EPDM rubber, 20g of tetrapropoxysilane and 5g of antioxidant 1010 were blended, stirred at a speed of 100r / min for 10min, and melt-extruded to obtain a flame-retardant SEBS / silicone rubber composite material. The melt extrusion temperature was set to 140°C for zone 1, 160°C for zone 2, 180°C for zone 3, and 200°C for zone 4.

[0034] Example 1.3 A method for preparing a flame retardant SEBS / silicone rubber composite material comprises the following steps: 350g SEBS, 300g silicone rubber, 75g of the composite flame retardant prepared in Preparation Example 1.1, 75g of an inorganic flame retardant filler (43.75g of PEG-modified magnesium hydroxide prepared in Preparation Example 2.1 and 31.25g of hydrotalcite), 60g of hexamethyldisiloxane, 60g of ethylene propylene diene monomer rubber, 15g of tetrapropoxysilane and 10g of antioxidant 1010 were blended, stirred at a speed of 100r / min for 10min, and melt-extruded to obtain a flame-retardant SEBS / silicone rubber composite material. The melt extrusion temperature was set to 160°C for zone 1, 180°C for zone 2, 200°C for zone 3 and 220°C for zone 4.

[0035] Example 1.4 A method for preparing a flame retardant SEBS / silicone rubber composite material comprises the following steps: 450g SEBS, 300g silicone rubber, 75g of the composite flame retardant prepared in Preparation Example 1.1, 75g of an inorganic flame retardant filler (43.75g of PEG-modified magnesium hydroxide prepared in Preparation Example 2.1 and 31.25g of hydrotalcite), 60g of hexamethyldisiloxane, 40g of EPDM rubber, 15g of tetrapropoxysilane and 15g of antioxidant 1010 were blended, stirred at a speed of 100r / min for 10min, and melt-extruded to obtain a flame-retardant SEBS / silicone rubber composite material. The melt extrusion temperature was set to 160°C for zone 1, 180°C for zone 2, 200°C for zone 3 and 220°C for zone 4.

[0036] Example 2.1 A method for preparing a flame-retardant SEBS / silicone rubber composite material, which differs from Example 1.3 in that the inorganic flame-retardant filler consists of 54 g of PEG-modified magnesium hydroxide obtained in Preparation Example 2.1 and 36 g of hydrotalcite, and the rest is the same as Example 1.3.

[0037] Example 2.2 A method for preparing a flame-retardant SEBS / silicone rubber composite material, which differs from Example 1.3 in that the inorganic flame-retardant filler consists of 57 g of PEG-modified magnesium hydroxide obtained in Preparation Example 2.1 and 33 g of hydrotalcite, and the rest is the same as Example 1.3.

[0038] Example 2.3 A method for preparing a flame-retardant SEBS / silicone rubber composite material, which differs from Example 1.3 in that the inorganic flame-retardant filler consists of 59 g of PEG-modified magnesium hydroxide obtained in Preparation Example 2.1 and 31 g of hydrotalcite, and the rest is the same as Example 1.3.

[0039] Example 3.1 A method for preparing a flame-retardant SEBS / silicone rubber composite material, which differs from Example 2.2 in that the inorganic flame-retardant filler consists of 40.375 g of PEG-modified magnesium hydroxide prepared in Preparation Example 2.1, 23.375 g of hydrotalcite, and 11.25 g of red phosphorus. The rest is the same as Example 2.2.

[0040] Example 3.2 A method for preparing a flame-retardant SEBS / silicone rubber composite material, which differs from Example 2.2 in that the inorganic flame-retardant filler consists of 38 g of PEG-modified magnesium hydroxide obtained in Preparation Example 2.1, 22 g of hydrotalcite, and 15 g of red phosphorus; the rest is the same as Example 2.2.

[0041] Example 4 A method for preparing a flame-retardant SEBS / silicone rubber composite material, which differs from Example 3.2 in that the PEG-modified magnesium hydroxide prepared in Preparation Example 2.1 is replaced by the PEG-modified magnesium hydroxide prepared in Preparation Example 2.3, and the rest is the same as Example 3.2.

[0042] Example 5 A method for preparing a flame-retardant SEBS / silicone rubber composite material, which differs from Example 1.3 in that the composite flame retardant prepared in Preparation Example 1.1 is replaced by the composite flame retardant prepared in Preparation Example 1.3, and the rest is the same as Example 1.3.

[0043] Comparative Example 1.1 The difference from Example 1.3 is that the inorganic flame retardant filler is removed, the amount of the composite flame retardant prepared in Preparation Example 1.1 is 150 g, and the rest is the same as Example 1.3.

[0044] Comparative Example 1.2 The difference from Example 1.3 is that the composite flame retardant prepared in Preparation Example 1.1 is removed, the amount of inorganic flame retardant filler used is 150g (87.5g PEG-modified magnesium hydroxide prepared in Preparation Example 2.1 and 62.5g hydrotalcite), and the rest is the same as Example 1.3.

[0045] Comparative Example 1.3 The difference from Example 1.3 is that all inorganic flame retardant fillers are replaced by nano-montmorillonite, and the rest are the same as Example 1.3.

[0046] Comparative Example 1.4 The difference from Example 1.3 is that the composite flame retardant prepared in Preparation Example 1.1 is completely replaced with resorcinol tetraphenyl bisphosphate, and the rest is the same as Example 1.3.

[0047] Comparative Example 2.1 The difference from Example 1.3 is that 75 g of the composite flame retardant prepared in Preparation Example 1.1 and 75 g of the inorganic flame retardant filler (43.75 g of PEG-modified magnesium hydroxide prepared in Preparation Example 2.1 and 31.25 g of hydrotalcite) are replaced with 100 g of resorcinol tetraphenyl bisphosphate and 150 g of melamine cyanurate. The rest is the same as Example 1.3.

[0048] Comparative Example 2.2 The difference from Example 1.3 is that 75g of the composite flame retardant prepared in Preparation Example 1.1 and 75g of the inorganic flame retardant filler (43.75g of PEG-modified magnesium hydroxide prepared in Preparation Example 2.1 and 31.25g of hydrotalcite) are replaced with 150g of aluminum hydroxide and 100g of ammonium polyphosphate, and the rest are the same as Example 1.3.

[0049] Comparative Example 2.3 The difference from Example 1.3 is that 75g of the composite flame retardant prepared in Preparation Example 1.1 and 75g of the inorganic flame retardant filler (43.75g of PEG-modified magnesium hydroxide prepared in Preparation Example 2.1 and 31.25g of hydrotalcite) are replaced with 100g of nano-montmorillonite and 150g of expanded graphite, and the rest are the same as Example 1.3.

[0050] Comparative Example 3.1 The difference from Example 1.3 is that the PEG-modified magnesium hydroxide prepared in Preparation Example 2.1 is removed, the amount of hydrotalcite used is 75 g, and the rest is the same as Example 1.3.

[0051] Comparative Example 3.2 The difference from Example 1.3 is that the hydrotalcite is removed, the amount of PEG-modified magnesium hydroxide prepared in Preparation Example 2.1 is 75 g, and the rest is the same as Example 1.3.

[0052] Performance testing First, 500g SEBS, 200g silicone rubber, 40g hexamethyldisiloxane, 80g EPDM rubber, 10g tetrapropoxysilane and 20g antioxidant 1010 were stirred at a speed of 100r / min for 10min and melt-extruded to obtain a common SEBS / silicone rubber composite material. As a control group, the melt extrusion temperature was set to 160℃ for zone 1, 180℃ for zone 2, 200℃ for zone 3 and 220℃ for zone 4.

[0053] 1. Flame retardancy: The limiting oxygen index (LOI) of the flame-retardant SEBS / silicone rubber composite materials obtained in the control group, examples, and comparative examples was measured using a limiting oxygen index instrument. The rate of change of each example and comparative example compared to the control group was calculated, and the results are recorded in Table 1. 2. Hardness: In accordance with GB / T 6031-2017, the hardness (HA) of the flame-retardant SEBS / silicone rubber composites obtained in the control group, examples, and comparative examples was measured using a Shore hardness tester. The rate of change of each example and comparative example compared to the control group was calculated, and the results are recorded in Table 1.

[0054] Table 1 Performance test table Data Analysis: As can be seen from Table 1, the limiting oxygen index change rate of the flame retardant SEBS / silicone rubber composite materials of Examples 1.1-1.2 of the present application is 39.5-39.7%, and the hardness change rate is 18.0-18.4%, which proves that the amount of flame retardant added in the flame retardant SEBS / silicone rubber composite materials of the present application is low, but the flame retardant effect is good.

[0055] Compared with Examples 1.1-1.2, the material ratios of Examples 1.3-1.4 have been further optimized. The results show that the limiting oxygen index change rate of the flame-retardant SEBS / silicone rubber composite material has increased, and the hardness change rate has decreased, which proves that the present application adjusts the weight ratio of each raw material to better exert the synergistic effect of each raw material, so that the composite material has both moderate hardness and excellent flame retardancy, while maintaining good thermoplastic processing advantages and flexibility.

[0056] The difference between Examples 2.1-2.3 and Example 1.3 is that the present application changes the ratio of PEG-modified magnesium hydroxide and hydrotalcite. The results show that the rate of change of the limiting oxygen index of the flame-retardant SEBS / silicone rubber composite material of Example 2.2 is significantly improved, proving that the present application combines PEG-modified magnesium hydroxide and hydrotalcite in the inorganic flame-retardant filler in a specific weight ratio of 38:22, which can further optimize the synergistic effect with the composite flame retardant, thereby better improving the flame retardant properties of the flame-retardant SEBS / silicone rubber composite material while reducing the amount of flame retardant added, and helping to maintain a moderate hardness of the material.

[0057] The difference between Example 3.1-3.2 and Example 2.2 is that red phosphorus is also added to the inorganic flame retardant filler in this application. The results show that the limiting oxygen index change rate of the flame retardant SEBS / silicone rubber composite material of Examples 3.1-3.2 is significantly improved, and the hardness change rate is not obvious and can be ignored, which proves that red phosphorus can play a better synergistic role with other flame retardants, so that the SEBS / silicone rubber composite material can still maintain a good flame retardant effect at a low amount of flame retardant added, so that the material has both moderate hardness and excellent flame retardancy.

[0058] The difference between Example 4 and Example 3.2 is that the present application changes the specific parameters in the preparation method of PEG-modified magnesium hydroxide. The results show that the hardness index change rate of the flame-retardant SEBS / silicone rubber composite material of Example 4 decreases, and the limiting oxygen index change rate is significantly improved. This proves that the present application optimizes the specific parameters in the preparation method of PEG-modified magnesium hydroxide, which can further reduce the particle size of PEG-modified magnesium hydroxide, ensure a more sufficient dispersion effect, and make it more fully dispersed in the matrix. It synergizes with the composite flame retardant, and can greatly improve the flame retardant effect of the SEBS / silicone rubber composite material while reducing the amount of flame retardant added.

[0059] The difference between Example 5 and Example 1.3 is that the specific parameters in the preparation method of the composite flame retardant are changed in the present application. The results show that the rate of change of the limiting oxygen index of the flame-retardant SEBS / silicone rubber composite material of Example 5 is significantly improved, proving that the composite flame retardant prepared in the present application by using a specific weight ratio of melamine, resorcinol and formaldehyde can significantly improve the flame retardant ability of the flame-retardant SEBS / silicone rubber composite material while reducing the amount of flame retardant added.

[0060] The difference between Comparative Examples 1.1-1.2 and Example 1.3 is that the present application removes the inorganic flame retardant filler and the composite flame retardant, respectively. The difference between Comparative Examples 1.1-1.2 and Example 1.3 is that the present application replaces the inorganic flame retardant filler and the composite flame retardant with other substances, respectively. The results show that the limiting oxygen index change rate of the flame-retardant SEBS / silicone rubber composite materials of Comparative Examples 1.1-1.4 is greatly reduced, proving that the inorganic flame retardant filler and the composite flame retardant of the present application can play a good synergistic role and greatly improve the flame retardant effect.

[0061] The difference between Comparative Examples 2.1-2.3 and Example 1.3 is that the present application replaces the inorganic flame retardant filler and the composite flame retardant with other flame retardant substances, and increases the dosage by 150wt%. The results show that the limiting oxygen index change rate of Comparative Examples 2.1-2.3 is not significantly different from that of Example 1.3, but the hardness index change rate has increased significantly, proving that the amount of flame retardant added in the flame retardant SEBS / silicone rubber composite material of the present application is low, but the flame retardant effect is good, and it has the characteristic of low hardness change rate, and still maintains the advantage of a wide range of applications of the flame retardant SEBS / silicone rubber composite material.

[0062] The difference between Comparative Examples 3.1-3.2 and Example 1.3 is that the present application removes the PEG-modified magnesium hydroxide and hydrotalcite in the inorganic flame retardant filler respectively. The results show that the limiting oxygen index change rate of the flame-retardant SEBS / silicone rubber composite material of Comparative Examples 3.1-3.2 is reduced, which proves that the PEG-modified magnesium hydroxide and hydrotalcite in the present application have a good synergistic effect, which can greatly improve the flame retardant effect while reducing the amount of flame retardant added.

[0063] The embodiments of this specific implementation method are all preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A flame retardant SEBS / silicone rubber composite material, characterized in that: The raw materials used include the following components by weight: SEBS 30-50 parts; 20-40 parts of silicone rubber; 6-9 parts of composite flame retardant; 6-9 parts of inorganic flame retardant filler; 4-8 parts of diluent; 3-8 parts of compatibilizer; 1-2 parts of cross-linking agent; 0.5-2 parts of antioxidant; The composite flame retardant is prepared from melamine, resorcinol and formaldehyde, and the inorganic flame retardant filler comprises PEG-modified magnesium hydroxide and hydrotalcite in a weight ratio of (35-40): (20:25).

2. The flame retardant SEBS / silicone rubber composite material according to claim 1, characterized in that: The raw materials used include the following components by weight: 35-45 parts of SEBS; 30 parts of silicone rubber; 7.5 parts of composite flame retardant; 7.5 parts of inorganic flame retardant filler; 6 parts of diluent; 4-6 parts of compatibilizer; 1.5 parts of cross-linking agent; 1-1.5 parts of antioxidant.

3. The flame retardant SEBS / silicone rubber composite material according to claim 1, characterized in that: The inorganic flame retardant filler includes PEG-modified magnesium hydroxide and hydrotalcite in a weight ratio of 38:

22.

4. The flame retardant SEBS / silicone rubber composite material according to claim 1, characterized in that: The inorganic flame retardant filler further comprises red phosphorus, and the amount of red phosphorus used is 15-20wt% of the total amount of the inorganic flame retardant filler.

5. A method for preparing the flame-retardant SEBS / silicone rubber composite material according to claims 1-4, characterized in that: The method comprises the following steps: blending SEBS, silicone rubber, a composite flame retardant, an inorganic flame retardant filler, a diluent, a compatibilizer, a crosslinking agent and an antioxidant, and melt-extruding to obtain a flame retardant SEBS / silicone rubber composite material, wherein the temperature of the melt extrusion is set to: 140-160°C for zone one, 160-180°C for zone two, 180-200°C for zone three, and 200-220°C for zone four.

6. The method for preparing a flame retardant SEBS / silicone rubber composite material according to claim 5, characterized in that: The composite flame retardant is prepared by the following method: melamine, resorcinol and formaldehyde in a weight ratio of 20:(15-20):(22-24) are mixed and reacted, and then placed at a temperature of 75-85°C for 2-2.5 hours, filtered, and the obtained solid is washed and dried to obtain the composite flame retardant.

7. The method for preparing a flame retardant SEBS / silicone rubber composite material according to claim 6, characterized in that: The weight ratio of melamine, resorcinol and formaldehyde is 20:17:

23.

8. The method for preparing a flame retardant SEBS / silicone rubber composite material according to claim 5, characterized in that: The PEG-modified magnesium hydroxide in the inorganic flame-retardant filler is prepared by the following method: sodium hydroxide, magnesium nitrate and PEG6000 are blended and dispersed in water, reacted, filtered, the obtained solid is washed, and dried to obtain PEG-modified magnesium hydroxide, the concentration of magnesium nitrate in the system is controlled to be 0.4-0.8 mol / L, and the amount of PEG6000 is 2-5wt% of the total amount of sodium hydroxide and magnesium nitrate.

9. The method for preparing a flame retardant SEBS / silicone rubber composite material according to claim 8, characterized in that: The concentration of magnesium nitrate in the control system was 0.5 mol / L.

10. The method for preparing a flame retardant SEBS / silicone rubber composite material according to claim 8, characterized in that: The amount of PEG6000 used is 4 wt % of the total amount of sodium hydroxide and magnesium nitrate.

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