Surface-modified bromide flame retardant and method for its preparation

Abstract

This invention belongs to the field of flame retardant technology, specifically relating to a surface-modified bromide flame retardant and its preparation method. Using tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene as raw materials, a high molecular weight brominated epoxy resin flame retardant is prepared by reaction under the action of benzyltriphenylphosphine bromide catalyst. Subsequently, the high molecular weight brominated epoxy resin flame retardant is modified and grafted with a cyclotriphosphazene modifier to obtain a surface-modified high molecular weight brominated epoxy resin flame retardant. This invention uses tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene to synthesize a high molecular weight brominated epoxy resin flame retardant. The introduced naphthalene group can greatly improve the thermal stability of the flame retardant. Simultaneously, the surface grafting modification of the high molecular weight brominated epoxy resin flame retardant with a cyclotriphosphazene modifier introduces cyclotriphosphazene, which has a high char-forming ability. The char layer generated during the flame-retardant process can improve the smoke problem of the brominated epoxy resin flame retardant.

Description

Technical Field

[0001] This invention belongs to the field of flame retardant technology, specifically relating to a surface-modified bromide flame retardant and its preparation method. Background Technology

[0002] Brominated flame retardants have high flame retardant efficiency and can meet the requirements of various polymer processing technologies and flame retardant products. Their flame retardant mechanism is mainly the interaction between the gas phase and the condensed phase. In polymer flame retardancy, they can quickly retard flames. The bromine free radicals generated during the reaction can capture hydrogen from the polymer backbone to generate the flammable gas hydrogen bromide. This not only dilutes oxygen but also reacts with various active free radicals, deactivating them. Hydrogen bromide can then be oxidized again to bromine free radicals to continue participating in the reaction. This cycle repeats, inhibiting the chain reaction of combustion and continuously slowing down the combustion rate until it is extinguished.

[0003] In recent years, the development of brominated flame retardants has been affected by problems such as dioxins and bioaccumulation, and there is an urgent need for an environmentally friendly brominated flame retardant.

[0004] Polymerizable brominated flame retardants exhibit good compatibility with polymers, are resistant to exudation, and are suitable for most general-purpose engineering plastics. Furthermore, the greatest advantage of polymerizable brominated flame retardants is that they do not produce carcinogenic substances such as dioxins during combustion. Due to their high molecular weight, they are difficult to penetrate cell membranes in living organisms to participate in systemic circulation and metabolism, thus effectively avoiding bioaccumulation and significantly reducing their environmental impact—a feat unmatched by traditional small-molecule brominated flame retardants.

[0005] Brominated epoxy resin, as an environmentally friendly brominated flame retardant, is now entering a phase of intensive research and development. However, the thermal stability of brominated epoxy resin flame retardants still needs improvement, and the smoke generation during combustion is a serious problem. Summary of the Invention

[0006] The purpose of this invention is to provide a surface-modified bromide flame retardant and its preparation method to solve the above-mentioned technical problems.

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

[0008] A method for preparing a surface-modified bromide flame retardant includes the following steps:

[0009] S1. Weigh out tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene, then add cyclohexanone solvent to obtain a reaction solution. Heat the reaction solution to 150~160℃, add benzyltriphenylphosphine bromide catalyst, and stir the reaction under a nitrogen atmosphere. Adjust the concentration of the reaction system during the reaction. After reacting for 8~9 hours, cool the reaction system to room temperature, add the reaction system to anhydrous ethanol, filter and dry to obtain a high molecular weight brominated epoxy resin flame retardant.

[0010] S2. Dissolve hexachlorocyclotriphosphazene in acetonitrile, then add triethylamine and KH550, heat to 80~85℃ and react for 4~4.5h, then add ethanolamine and continue the reaction for 4~4.5h. After the reaction is complete, let stand for 30min, filter, and rotary evaporate the filtrate to obtain siloxane cyclotriphosphazene.

[0011] S3. Add siloxane cyclotriphosphazene to an ethanol solution containing ferric nitrate and let stand for 12-24 hours to obtain cyclotriphosphazene modifier.

[0012] S4. Add the high molecular weight brominated epoxy resin flame retardant to the flask, heat it to 130~150℃ under a nitrogen atmosphere, then add the cyclotriphosphazene modifier and the catalyst tetraisopropyl titanate, stir and react for 7~8h. After the reaction is completed, wash the reaction system twice with toluene to obtain the surface-modified high molecular weight brominated epoxy resin flame retardant.

[0013] As a further improvement, in step S1, the molar ratio of tetrabromobisphenol A glycidyl ether to 2,7-dihydroxynaphthalene in the reaction solution is 63~65:62, and the amount of cyclohexanone solvent added is 21~26% of the mass of tetrabromobisphenol A glycidyl ether.

[0014] As a further improvement, in step S1, adjusting the concentration of the reaction system during the reaction process specifically involves adding 20-24% (by mass) of the tetrabromobisphenol A glycidyl ether cyclohexanone solvent to the reaction system when stirring becomes difficult.

[0015] As a further improvement, in step S2, the molar ratio of hexachlorocyclotriphosphazene, triethylamine and KH550 is 1:1:4, and the molar ratio of ethanolamine and hexachlorocyclotriphosphazene is 2~2.1:1.

[0016] As a further improvement, in step S3, the mass of the ferric nitrate in the ethanol solution is 1 to 1.5% of the mass of the siloxane cyclotriphosphazene.

[0017] As a further improvement, in step S4, the mass ratio of the high molecular weight brominated epoxy resin flame retardant to the cyclotriphosphazene modifier is 10~20:1.

[0018] As a further improvement, in step S1, the preparation method of the tetrabromobisphenol A glycidyl ether is as follows: tetrabromobisphenol A and epichlorohydrin are added to a methyl isobutyl ketone solvent, heated and stirred until dissolved to form a reaction solution. While stirring, a sodium hydroxide aqueous solution with a mass concentration of 40-50% is added to the solution, and the mixture is refluxed for 3-4 hours. After the reaction is completed, methyl isobutyl ketone is added to dilute the solution. Then, while stirring, a sodium hydroxide aqueous solution with a mass concentration of 20-30% is added to the solution, and the mixture is refluxed for another 3-4 hours. After the reaction is completed, the pH of the system is adjusted to neutral, and the solution is washed three times with deionized water at 70-80°C. The organic phase is then distilled under reduced pressure to obtain tetrabromobisphenol A glycidyl ether.

[0019] As a further improvement, the molar ratio of tetrabromobisphenol A to epichlorohydrin is 1:2, the molar amount of sodium hydroxide in the 40-50% sodium hydroxide aqueous solution is 0.12-0.15 times the molar amount of tetrabromobisphenol A, and the molar amount of sodium hydroxide in the 20-30% sodium hydroxide solution is 1-1.02 times the molar amount of tetrabromobisphenol A.

[0020] The present invention also provides a surface-modified bromide flame retardant.

[0021] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0022] This invention provides a surface-modified bromide flame retardant. A high molecular weight brominated epoxy resin flame retardant is synthesized using tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene. The introduced naphthalene group significantly improves the thermal stability of the flame retardant. Simultaneously, a prepared cyclotriphosphazene modifier is used to perform surface grafting modification on the high molecular weight brominated epoxy resin flame retardant, introducing cyclotriphosphazene with high char-forming ability. The char layer generated during the flame-retardant process improves the smoke generation problem of the brominated epoxy resin flame retardant.

[0023] In this invention, a two-step method is used to prepare tetrabromobisphenol A glycidyl ether. The molar ratio of tetrabromobisphenol A to epichlorohydrin is 1:2. A sodium hydroxide solution with a mass fraction of 40-50% is used in the ring-opening reaction, and a sodium hydroxide solution with a mass fraction of 20-30% is used in the ring-closing reaction. The resulting tetrabromobisphenol A glycidyl ether has a lower epoxy equivalent, which can reach 400 g / mol.

[0024] In this invention, after adding siloxane cyclotriphosphazene to an ethanol solution containing ferric nitrate, the surface-modified high molecular weight brominated epoxy resin flame retardant prepared by it has a higher char-forming ability. Iron ions can act as a catalyst in the flame retardant process to promote the char-forming reaction, thereby significantly enhancing the fire resistance and thermal stability of the material. Attached Figure Description

[0025] Figure 1 This is the infrared spectrum of the high molecular weight brominated epoxy resin prepared in Example 1;

[0026] Figure 2 This is the infrared spectrum of the siloxane cyclotriphosphazene prepared in Example 1;

[0027] Figure 3 This is the infrared spectrum of the surface-modified high molecular weight brominated epoxy resin flame retardant prepared in Example 1;

[0028] Figure 4 These are the thermogravimetric curves of flame retardants in Example 1 and Comparative Examples 1-4;

[0029] Figure 5 These are the smoke release rate (SPR) curves of polymer material samples prepared with flame retardants in Examples 1 and Comparative Examples 1-4. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0031] Example 1: A method for preparing a surface-modified bromide flame retardant, comprising the following steps:

[0032] S1. Add 0.5 mol tetrabromobisphenol A and 1 mol epichlorohydrin to 120 mL methyl isobutyl ketone solvent, heat and stir until dissolved to form a reaction solution. While stirring, add 5.78 g of 45% sodium hydroxide aqueous solution and reflux for 3.5 h. After the reaction is complete, add 180 mL of methyl isobutyl ketone to dilute. Then, while stirring, add 80.8 g of 25% sodium hydroxide aqueous solution and continue to reflux for 3.5 h. After the reaction is complete, adjust the pH of the system to neutral with sodium dihydrogen phosphate, then wash three times with deionized water at 75 °C. Distill the organic phase under reduced pressure to obtain tetrabromobisphenol A glycidyl ether.

[0033] In this embodiment, the epoxy equivalent of the obtained tetrabromobisphenol A glycidyl ether is about 400 g / mol, and the determination method is the hydrochloric acid acetone method.

[0034] The reaction equation is:

[0035] ;

[0036] S2. Weigh out tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene, then add cyclohexanone solvent to obtain a reaction solution. Heat the reaction solution to 155℃, add benzyltriphenylphosphine bromide catalyst, and stir the reaction under a nitrogen atmosphere. During the reaction, when the reaction system is difficult to stir, add 20% by mass of tetrabromobisphenol A glycidyl ether in cyclohexanone solvent to the reaction system to adjust the concentration of the reaction system. The reaction process lasts for 8.5 hours. Then, cool the reaction system to room temperature, pour the reaction system into anhydrous ethanol, filter and dry to obtain a high molecular weight brominated epoxy resin flame retardant.

[0037] In the reaction solution, the molar ratio of tetrabromobisphenol A glycidyl ether to 2,7-dihydroxynaphthalene is 63:62, and the amount of cyclohexanone solvent added is 21% of the mass of tetrabromobisphenol A glycidyl ether.

[0038] The amount of catalyst benzyltriphenylphosphine bromide added is 0.2% of the mass of tetrabromobisphenol A glycidyl ether;

[0039] In this embodiment, the average molecular weight of the high molecular weight brominated epoxy resin is 5.98 × 10⁻⁶. 4 Da, its infrared spectrum is as follows Figure 1 As shown, by Figure 1 It can be seen that 871.71cm -1 933.42cm -1 798.42cm -1 This is an asymmetric stretching vibration of -COC- in the epoxy group, 3444.41 cm⁻¹ -1 This is a hydroxyl stretching vibration, 1646.99 cm⁻¹ -1 1585.278cm -1 1533.207cm -1 The characteristic peaks for benzene and naphthalene rings are 736.71 cm⁻¹. -1 667.28cm -1 642.21cm -1 The absorption peak is C-Br, at 831 cm⁻¹. -1 The peak at this point represents the stretching vibration of the adjacent hydrogen atom in the naphthalene ring.

[0040] S3. Dissolve 0.3 mol hexachlorocyclotriphosphazene in 2 L of acetonitrile, then add 0.3 mol triethylamine and 1.2 mol γ-aminopropyltriethoxysilane (KH550), heat to 80 °C and react for 4.5 h, then add 0.6 mol ethanolamine and continue the reaction for 4.5 h. After the reaction is complete, let stand for 30 min, filter, and rotary evaporate the filtrate to obtain siloxane cyclotriphosphazene.

[0041] The reaction equation is:

[0042]

[0043] ;

[0044] The infrared spectrum of siloxane cyclotriphosphazene is as follows: Figure 2 As shown, by Figure 2 It can be seen that 790cm -1 and 1072cm -1 Characteristic peaks belonging to Si-O-Si appear at 2975 cm⁻¹, and also at 2975 cm⁻¹. -1 Stretching vibrations of CH occur at 880 cm. -1 and 1191cm -1 The PN and P=N absorption peaks characteristic of the phosphazene skeleton appear at this location;

[0045] S4. Add 100g of siloxane cyclotriphosphazene to an ethanol solution containing 1g of ferric nitrate, let stand for 24h, and obtain cyclotriphosphazene modifier.

[0046] S5. Add 200g of high molecular weight brominated epoxy resin flame retardant to a flask, heat to 140℃ under a nitrogen atmosphere, then add 15g of cyclotriphosphazene modifier and 0.3g of tetraisopropyl titanate catalyst, stir and react for 7.5h. After the reaction is complete, wash the reaction system twice with toluene to obtain surface-modified high molecular weight brominated epoxy resin flame retardant.

[0047] In this embodiment, the infrared spectrum of the surface-modified high molecular weight brominated epoxy resin flame retardant is as follows: Figure 3 As shown, by Figure 3 It can be seen that, Figure 2 2885cm -1 The characteristic alkoxy peak at that location disappeared. Figure 1 3479cm -1 The signal of the -OH group at the site increases because hydroxyl groups are also present in the cyclotriphosphazene modifier.

[0048] Example 2: A method for preparing a surface-modified bromide flame retardant, comprising the following steps:

[0049] S1. Add 0.5 mol tetrabromobisphenol A and 1 mol epichlorohydrin to 120 mL methyl isobutyl ketone solvent, heat and stir until dissolved to form a reaction solution. While stirring, add 6.0 g of 50% sodium hydroxide aqueous solution and reflux for 4 h. After the reaction is complete, add 190 mL of methyl isobutyl ketone to dilute. Then, while stirring, add 68.0 g of 30% sodium hydroxide aqueous solution and continue to reflux for 4 h. After the reaction is complete, adjust the pH of the system to neutral with sodium dihydrogen phosphate, then wash three times with deionized water at 80 °C. Distill the organic phase under reduced pressure to obtain tetrabromobisphenol A glycidyl ether.

[0050] S2. Weigh out tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene, then add cyclohexanone solvent to obtain a reaction solution. Heat the reaction solution to 150℃, add benzyltriphenylphosphine bromide catalyst, and stir the reaction under a nitrogen atmosphere. During the reaction, when the reaction system is difficult to stir, add 22% (by mass) of tetrabromobisphenol A glycidyl ether in cyclohexanone solvent to the reaction system to adjust the concentration of the reaction system. The reaction process lasts for 9 hours. Then, cool the reaction system to room temperature, pour the reaction system into anhydrous ethanol, filter and dry to obtain a high molecular weight brominated epoxy resin flame retardant.

[0051] In the reaction solution, the molar ratio of tetrabromobisphenol A glycidyl ether to 2,7-dihydroxynaphthalene is 65:62, and the amount of cyclohexanone solvent added is 24% of the mass of tetrabromobisphenol A glycidyl ether;

[0052] The amount of catalyst benzyltriphenylphosphine bromide added is 0.2% of the mass of tetrabromobisphenol A glycidyl ether;

[0053] S3. Dissolve 0.3 mol hexachlorocyclotriphosphazene in 2 L of acetonitrile, then add 0.3 mol triethylamine and 1.2 mol γ-aminopropyltriethoxysilane (KH550), heat to 85 °C and react for 4 h, then add 0.63 mol ethanolamine and continue the reaction for 4 h. After the reaction is complete, let stand for 30 min, filter, and rotary evaporate the filtrate to obtain siloxane cyclotriphosphazene.

[0054] S4. Add 100g of siloxane cyclotriphosphazene to an ethanol solution containing 1.5g of ferric nitrate, let stand for 12h, and obtain cyclotriphosphazene modifier.

[0055] S5. Add 200g of high molecular weight brominated epoxy resin flame retardant to a flask, heat to 150℃ under a nitrogen atmosphere, then add 10g of cyclotriphosphazene modifier and 0.3g of tetraisopropyl titanate catalyst, stir and react for 7h. After the reaction is completed, wash the reaction system twice with toluene to obtain surface-modified high molecular weight brominated epoxy resin flame retardant.

[0056] Example 3 A method for preparing a surface-modified bromide flame retardant, comprising the following steps:

[0057] S1. Add 0.5 mol tetrabromobisphenol A and 1 mol epichlorohydrin to 120 mL methyl isobutyl ketone solvent, heat and stir until dissolved to form a reaction solution. While stirring, add 6.0 g of 40% sodium hydroxide aqueous solution and reflux for 3 h. After the reaction is complete, add 180 mL of methyl isobutyl ketone to dilute. Then, while stirring, add 100 g of 20% sodium hydroxide aqueous solution and continue to reflux for 3 h. After the reaction is complete, adjust the pH of the system to neutral with sodium dihydrogen phosphate, then wash three times with deionized water at 70 °C. Distill the organic phase under reduced pressure to obtain tetrabromobisphenol A glycidyl ether.

[0058] S2. Weigh out tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene, then add cyclohexanone solvent to obtain a reaction solution. Heat the reaction solution to 160℃, add benzyltriphenylphosphine bromide catalyst, and stir the reaction under a nitrogen atmosphere. During the reaction, when the reaction system is difficult to stir, add 24% (by mass) of tetrabromobisphenol A glycidyl ether in cyclohexanone solvent to the reaction system to adjust the concentration of the reaction system. The reaction process lasts for 8 hours. Then, cool the reaction system to room temperature, pour the reaction system into anhydrous ethanol, filter and dry to obtain a high molecular weight brominated epoxy resin flame retardant.

[0059] In the reaction solution, the molar ratio of tetrabromobisphenol A glycidyl ether to 2,7-dihydroxynaphthalene is 64:62, and the amount of cyclohexanone solvent added is 26% of the mass of tetrabromobisphenol A glycidyl ether;

[0060] The amount of catalyst benzyltriphenylphosphine bromide added is 0.2% of the mass of tetrabromobisphenol A glycidyl ether;

[0061] S3. Dissolve 0.3 mol of hexachlorocyclotriphosphazene in 2 L of acetonitrile, then add 0.3 mol of triethylamine and 1.2 mol of γ-aminopropyltriethoxysilane (KH550), heat to 83 °C and react for 4.3 h, then add 0.6 mol of ethanolamine and continue the reaction for 4.3 h. After the reaction is complete, let stand for 30 min, filter, and rotary evaporate the filtrate to obtain siloxane cyclotriphosphazene.

[0062] S4. Add 100g of siloxane cyclotriphosphazene to an ethanol solution containing 1.3g of ferric nitrate, let stand for 18h, and obtain cyclotriphosphazene modifier.

[0063] S5. Add 200g of high molecular weight brominated epoxy resin flame retardant to a flask, heat to 130℃ under a nitrogen atmosphere, then add 20g of cyclotriphosphazene modifier and 0.3g of tetraisopropyl titanate catalyst, stir and react for 8h. After the reaction is completed, wash the reaction system twice with toluene to obtain surface-modified high molecular weight brominated epoxy resin flame retardant.

[0064] Comparative Example 1: A method for preparing a surface-modified bromide flame retardant, the specific preparation method is the same as that in Example 1, the difference being that in step S2, tetrabromobisphenol A is used instead of 2,7-dihydroxynaphthalene to prepare a high molecular weight brominated epoxy resin flame retardant. The specific steps are as follows:

[0065] S1. Add 0.5 mol tetrabromobisphenol A and 1 mol epichlorohydrin to 120 mL methyl isobutyl ketone solvent, heat and stir until dissolved to form a reaction solution. While stirring, add 5.78 g of 45% sodium hydroxide aqueous solution and reflux for 3.5 h. After the reaction is complete, add 180 mL of methyl isobutyl ketone to dilute. Then, while stirring, add 80.8 g of 25% sodium hydroxide aqueous solution and continue to reflux for 3.5 h. After the reaction is complete, adjust the pH of the system to neutral with sodium dihydrogen phosphate, then wash three times with deionized water at 75 °C. Distill the organic phase under reduced pressure to obtain tetrabromobisphenol A glycidyl ether.

[0066] S2. Weigh out tetrabromobisphenol A glycidyl ether and tetrabromobisphenol A, mix them, and then add cyclohexanone solvent to obtain a reaction solution. Heat the reaction solution to 155℃, add benzyltriphenylphosphine bromide catalyst, and stir the reaction under a nitrogen atmosphere. During the reaction, when the reaction system is difficult to stir, add 20% by mass of tetrabromobisphenol A glycidyl ether in cyclohexanone solvent to the reaction system to adjust the concentration of the reaction system. The reaction process lasts for 8.5 hours. Then, cool the reaction system to room temperature, pour the reaction system into anhydrous ethanol, filter and dry to obtain a high molecular weight brominated epoxy resin flame retardant.

[0067] In the reaction solution, the molar ratio of tetrabromobisphenol A glycidyl ether to 2,7-dihydroxynaphthalene is 63:62, and the amount of cyclohexanone solvent added is 21% of the mass of tetrabromobisphenol A glycidyl ether;

[0068] The amount of catalyst benzyltriphenylphosphine bromide added is 0.2% of the mass of tetrabromobisphenol A glycidyl ether;

[0069] In this comparative example, the molecular weight of the high molecular weight brominated epoxy resin flame retardant is 6.87 × 10⁻⁶. 4 Da;

[0070] S3. Dissolve 0.3 mol hexachlorocyclotriphosphazene in 2 L of acetonitrile, then add 0.3 mol triethylamine and 1.2 mol γ-aminopropyltriethoxysilane (KH550), heat to 80 °C and react for 4.5 h, then add 0.6 mol ethanolamine and continue the reaction for 4.5 h. After the reaction is complete, let stand for 30 min, filter, and rotary evaporate the filtrate to obtain siloxane cyclotriphosphazene.

[0071] S4. Add 100g of siloxane cyclotriphosphazene to an ethanol solution containing 1g of ferric nitrate, let stand for 24h, and obtain cyclotriphosphazene modifier.

[0072] S5. Add 200g of high molecular weight brominated epoxy resin flame retardant to a flask, heat to 140℃ under a nitrogen atmosphere, then add 15g of cyclotriphosphazene modifier and 0.3g of tetraisopropyl titanate catalyst, stir and react for 7.5h. After the reaction is complete, wash the reaction system twice with toluene to obtain surface-modified high molecular weight brominated epoxy resin flame retardant.

[0073] Comparative Example 2: A method for preparing a bromide flame retardant, the specific steps of which are the same as in Example 1, except that this comparative example does not use a cyclotriphosphazene modifier to modify the high molecular weight brominated epoxy resin flame retardant. The specific steps are as follows:

[0074] S1. Add 0.5 mol tetrabromobisphenol A and 1 mol epichlorohydrin to 120 mL methyl isobutyl ketone solvent, heat and stir until dissolved to form a reaction solution. While stirring, add 5.78 g of 45% sodium hydroxide aqueous solution and reflux for 3.5 h. After the reaction is complete, add 180 mL of methyl isobutyl ketone to dilute. Then, while stirring, add 80.8 g of 25% sodium hydroxide aqueous solution and continue to reflux for 3.5 h. After the reaction is complete, adjust the pH of the system to neutral with sodium dihydrogen phosphate, then wash three times with deionized water at 75 °C. Distill the organic phase under reduced pressure to obtain tetrabromobisphenol A glycidyl ether.

[0075] S2. Weigh out tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene, then add cyclohexanone solvent to obtain a reaction solution. Heat the reaction solution to 155℃, add benzyltriphenylphosphine bromide catalyst, and stir the reaction under a nitrogen atmosphere. During the reaction, when the reaction system is difficult to stir, add 20% by mass of tetrabromobisphenol A glycidyl ether in cyclohexanone solvent to the reaction system to adjust the concentration of the reaction system. The reaction process lasts for 8.5 hours. Then, cool the reaction system to room temperature, pour the reaction system into anhydrous ethanol, filter and dry to obtain a high molecular weight brominated epoxy resin flame retardant.

[0076] In the reaction solution, the molar ratio of tetrabromobisphenol A glycidyl ether to 2,7-dihydroxynaphthalene is 63:62, and the amount of cyclohexanone solvent added is 21% of the mass of tetrabromobisphenol A glycidyl ether;

[0077] The amount of catalyst benzyltriphenylphosphine bromide added is 0.2% of the mass of tetrabromobisphenol A glycidyl ether.

[0078] Comparative Example 3: A method for preparing a surface-modified bromide flame retardant, the specific steps of which are the same as in Example 1, except that this comparative example uses polydimethylsiloxane (PDMS) as a modifier to modify a high molecular weight brominated epoxy resin flame retardant. The specific steps are as follows:

[0079] S1. Add 0.5 mol tetrabromobisphenol A and 1 mol epichlorohydrin to 120 mL methyl isobutyl ketone solvent, heat and stir until dissolved to form a reaction solution. While stirring, add 5.78 g of 45% sodium hydroxide aqueous solution and reflux for 3.5 h. After the reaction is complete, add 180 mL of methyl isobutyl ketone to dilute. Then, while stirring, add 80.8 g of 25% sodium hydroxide aqueous solution and continue to reflux for 3.5 h. After the reaction is complete, adjust the pH of the system to neutral with sodium dihydrogen phosphate, then wash three times with deionized water at 75 °C. Distill the organic phase under reduced pressure to obtain tetrabromobisphenol A glycidyl ether.

[0080] S2. Weigh out tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene, then add cyclohexanone solvent to obtain a reaction solution. Heat the reaction solution to 155℃, add benzyltriphenylphosphine bromide catalyst, and stir the reaction under a nitrogen atmosphere. During the reaction, when the reaction system is difficult to stir, add 20% by mass of tetrabromobisphenol A glycidyl ether in cyclohexanone solvent to the reaction system to adjust the concentration of the reaction system. The reaction process lasts for 8.5 hours. Then, cool the reaction system to room temperature, pour the reaction system into anhydrous ethanol, filter and dry to obtain a high molecular weight brominated epoxy resin flame retardant.

[0081] In the reaction solution, the molar ratio of tetrabromobisphenol A glycidyl ether to 2,7-dihydroxynaphthalene is 63:62, and the amount of cyclohexanone solvent added is 21% of the mass of tetrabromobisphenol A glycidyl ether;

[0082] The amount of catalyst benzyltriphenylphosphine bromide added is 0.2% of the mass of tetrabromobisphenol A glycidyl ether;

[0083] S3. Add 200g of high molecular weight brominated epoxy resin flame retardant to a flask, heat to 140℃ under a nitrogen atmosphere, then add 15g of PDMS and 0.3g of tetraisopropyl titanate catalyst, stir and react for 7.5h. After the reaction is complete, wash the reaction system twice with toluene to obtain surface-modified high molecular weight brominated epoxy resin flame retardant.

[0084] Comparative Example 4: A method for preparing a bromide flame retardant, the specific steps of which are the same as those in Comparative Example 1, except that no modifier is used to modify the high molecular weight brominated epoxy resin flame retardant. The specific steps are as follows:

[0085] S1. Add 0.5 mol tetrabromobisphenol A and 1 mol epichlorohydrin to 120 mL methyl isobutyl ketone solvent, heat and stir until dissolved to form a reaction solution. While stirring, add 5.78 g of 45% sodium hydroxide aqueous solution and reflux for 3.5 h. After the reaction is complete, add 180 mL of methyl isobutyl ketone to dilute. Then, while stirring, add 80.8 g of 25% sodium hydroxide aqueous solution and continue to reflux for 3.5 h. After the reaction is complete, adjust the pH of the system to neutral with sodium dihydrogen phosphate, then wash three times with deionized water at 75 °C. Distill the organic phase under reduced pressure to obtain tetrabromobisphenol A glycidyl ether.

[0086] S2. Weigh out tetrabromobisphenol A glycidyl ether and tetrabromobisphenol A, mix them, and then add cyclohexanone solvent to obtain a reaction solution. Heat the reaction solution to 155℃, add benzyltriphenylphosphine bromide catalyst, and stir the reaction under a nitrogen atmosphere. During the reaction, when the reaction system is difficult to stir, add 20% by mass of tetrabromobisphenol A glycidyl ether in cyclohexanone solvent to the reaction system to adjust the concentration of the reaction system. The reaction process lasts for 8.5 hours. Then, cool the reaction system to room temperature, pour the reaction system into anhydrous ethanol, filter and dry to obtain a high molecular weight brominated epoxy resin flame retardant.

[0087] In the reaction solution, the molar ratio of tetrabromobisphenol A glycidyl ether to 2,7-dihydroxynaphthalene is 63:62, and the amount of cyclohexanone solvent added is 21% of the mass of tetrabromobisphenol A glycidyl ether;

[0088] The amount of catalyst benzyltriphenylphosphine bromide added is 0.2% of the mass of tetrabromobisphenol A glycidyl ether.

[0089] Thermogravimetric analysis (TGA) was performed on the flame retardants prepared in Example 1 and Comparative Examples 1-4. The thermogravimetric analyzer was used, and the test conditions were: heating from room temperature to 800°C in N2 atmosphere at a heating rate of 10°C / min.

[0090] Thermogravimetric curves of flame retardants in Example 1 and Comparative Examples 1-4 are as follows: Figure 4As shown in Table 1, the thermal weight loss of the flame retardants in Example 1 and Comparative Examples 1-4 is shown in Table 1.

[0091] Table 1. Thermal weight loss of flame retardants in Example 1 and Comparative Examples 1-4

[0092]

[0093] Depend on Figure 4 As can be seen from Table 1, the flame retardant in Example 1 has the highest thermal stability. Compared with Example 1, the flame retardants in Comparative Examples 1 and 4 have significantly reduced thermal stability without naphthalene groups. The flame retardant in Comparative Example 4 does not contain naphthalene groups and has not been modified, so its thermal stability is further reduced. This indicates that both naphthalene groups and modifiers have the effect of improving the thermal stability of flame retardants.

[0094] Compared with Example 1, Comparative Examples 2 and 3 also showed a certain degree of decrease in thermal stability, which also indicates that the modifier has a certain effect on improving the thermal stability of the flame retardant.

[0095] Using 150g of flame retardant from Examples 1 and 1-4, 6g of antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), 6g of antioxidant (tris(2,4-di-tert-butylphenyl) phosphite), and 840g of ABS resin (PA-757K type) as raw materials, polymer material samples were prepared. Cone calorimetry (CCT) was performed on the samples to determine the smoke suppression performance of the flame retardant. The specific testing method is based on existing technology. The smoke release rate (SPR) curves of the tested samples are shown below. Figure 5 As shown in Table 2, the results of the maximum smoke release rate (SPR) and total smoke release (TSR) of the samples are presented.

[0096] The specific preparation method of polymer material samples is as follows: after mixing the materials, they are extruded and granulated using a screw extruder. The heating curve is 130℃, 160℃, 190℃, 195℃, 200℃, 200℃, 200℃, 195℃, and 190℃, with the main machine speed at 70r / min. Then, the samples are shaped and prepared.

[0097] Table 2. Cone calorimetry results of the samples prepared with flame retardants in Example 1 and Comparative Examples 1-4.

[0098]

[0099] Depend on Figure 5As shown in Table 2, Example 1 had the lowest total smoke release, which was effectively reduced by using a cyclotriphosphazene modifier. Compared with Example 1, Comparative Example 1 had a slightly higher total smoke release, but the introduction of naphthalene rings could form char to some extent, thus improving the smoke problem to a certain degree. Compared with Example 1, Comparative Example 3 also showed some improvement in smoke problem due to polysiloxane modification, which could also form char to some extent. Compared with Example 1, Comparative Examples 2 and 4 did not modify the high molecular weight brominated epoxy resin flame retardant, and their smoke problems were very serious.

[0100] Comparative Example 5: This comparative example provides a method for preparing a high molecular weight brominated epoxy resin flame retardant. The difference from Example 1 is that the 45% sodium hydroxide aqueous solution is replaced with a 25% sodium hydroxide aqueous solution. The specific steps are as follows:

[0101] S1. Add 0.5 mol tetrabromobisphenol A and 1 mol epichlorohydrin to 120 mL methyl isobutyl ketone solvent, heat and stir until dissolved to form a reaction solution. While stirring, add 10.4 g of 25% sodium hydroxide aqueous solution and reflux for 3.5 h. After the reaction is complete, add 180 mL of methyl isobutyl ketone to dilute. Then, while stirring, add 80.8 g of 25% sodium hydroxide aqueous solution and continue to reflux for 3.5 h. After the reaction is complete, adjust the pH of the system to neutral with sodium dihydrogen phosphate, then wash three times with deionized water at 75 °C. Distill the organic phase under reduced pressure to obtain tetrabromobisphenol A glycidyl ether.

[0102] S2. Weigh out tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene, then add cyclohexanone solvent to obtain a reaction solution. Heat the reaction solution to 155℃, add benzyltriphenylphosphine bromide catalyst, and stir the reaction under a nitrogen atmosphere. During the reaction, when the reaction system is difficult to stir, add 20% by mass of tetrabromobisphenol A glycidyl ether in cyclohexanone solvent to the reaction system to adjust the concentration of the reaction system. The reaction process lasts for 8.5 hours. Then, cool the reaction system to room temperature, pour the reaction system into anhydrous ethanol, filter and dry to obtain a high molecular weight brominated epoxy resin flame retardant.

[0103] In the reaction solution, the molar ratio of tetrabromobisphenol A glycidyl ether to 2,7-dihydroxynaphthalene is 63:62, and the amount of cyclohexanone solvent added is 21% of the mass of tetrabromobisphenol A glycidyl ether;

[0104] The amount of catalyst benzyltriphenylphosphine bromide added is 0.2% of the mass of tetrabromobisphenol A glycidyl ether.

[0105] Comparative Example 6: This comparative example provides a method for preparing a high molecular weight brominated epoxy resin flame retardant. The difference from Example 1 is that the molar ratio of tetrabromobisphenol A and epichlorohydrin is 1:2.5. The specific steps are as follows:

[0106] S1. Add 0.5 mol tetrabromobisphenol A and 1.25 mol epichlorohydrin to 120 mL methyl isobutyl ketone solvent, heat and stir until dissolved to form a reaction solution. While stirring, add 5.78 g of 45% sodium hydroxide aqueous solution and reflux for 3.5 h. After the reaction is complete, add 180 mL of methyl isobutyl ketone to dilute. Then, while stirring, add 80.8 g of 25% sodium hydroxide aqueous solution and continue to reflux for 3.5 h. After the reaction is complete, adjust the pH of the system to neutral with sodium dihydrogen phosphate, then wash three times with deionized water at 75 °C. Distill the organic phase under reduced pressure to obtain tetrabromobisphenol A glycidyl ether.

[0107] S2. Weigh out tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene, then add cyclohexanone solvent to obtain a reaction solution. Heat the reaction solution to 155℃, add benzyltriphenylphosphine bromide catalyst, and stir the reaction under a nitrogen atmosphere. During the reaction, when the reaction system is difficult to stir, add 20% by mass of tetrabromobisphenol A glycidyl ether in cyclohexanone solvent to the reaction system to adjust the concentration of the reaction system. The reaction process lasts for 8.5 hours. Then, cool the reaction system to room temperature, pour the reaction system into anhydrous ethanol, filter and dry to obtain a high molecular weight brominated epoxy resin flame retardant.

[0108] In the reaction solution, the molar ratio of tetrabromobisphenol A glycidyl ether to 2,7-dihydroxynaphthalene is 63:62, and the amount of cyclohexanone solvent added is 21% of the mass of tetrabromobisphenol A glycidyl ether;

[0109] The amount of catalyst benzyltriphenylphosphine bromide added is 0.2% of the mass of tetrabromobisphenol A glycidyl ether.

[0110] The epoxy equivalent of tetrabromobisphenol A glycidyl ether and the molecular weight of the high molecular weight brominated epoxy resin flame retardant prepared in Comparative Examples 5 and 6 were determined respectively, and the results are shown in Table 3.

[0111] Table 3. Epoxy equivalent and molecular weight results for Example 1 and Comparative Examples 5-6

[0112]

[0113] As shown in Table 3, the concentration of sodium hydroxide aqueous solution and the amount of epichlorohydrin used both affect the epoxy equivalent of tetrabromobisphenol A glycidyl ether, and thus affect the molecular weight of the high molecular weight brominated epoxy resin flame retardant. In this invention, using appropriate alkali concentration and epichlorohydrin ratio during the preparation of tetrabromobisphenol A glycidyl ether is beneficial to increasing the molecular weight of the high molecular weight brominated epoxy resin flame retardant.

[0114] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a surface-modified bromide flame retardant, characterized in that, Includes the following steps: S1. Weigh out tetrabromobisphenol A glycidyl ether and 2,7-dihydroxynaphthalene, then add cyclohexanone solvent to obtain a reaction solution. Heat the reaction solution to 150~160℃, add benzyltriphenylphosphine bromide catalyst, and stir the reaction under a nitrogen atmosphere. Adjust the concentration of the reaction system during the reaction. After reacting for 8~9 hours, cool the reaction system to room temperature, add the reaction system to anhydrous ethanol, filter and dry to obtain a high molecular weight brominated epoxy resin flame retardant. S2. Dissolve hexachlorocyclotriphosphazene in acetonitrile, then add triethylamine and KH550, heat to 80~85℃ and react for 4~4.5h, then add ethanolamine and continue the reaction for 4~4.5h. After the reaction is complete, let stand for 30min, filter, and rotary evaporate the filtrate to obtain siloxane cyclotriphosphazene. S3. Add siloxane cyclotriphosphazene to an ethanol solution containing ferric nitrate and let stand for 12-24 hours to obtain cyclotriphosphazene modifier. S4. Add the high molecular weight brominated epoxy resin flame retardant to the flask, heat it to 130~150℃ under a nitrogen atmosphere, then add the cyclotriphosphazene modifier and the catalyst tetraisopropyl titanate, stir and react for 7~8h. After the reaction is completed, wash the reaction system twice with toluene to obtain the surface-modified high molecular weight brominated epoxy resin flame retardant.

2. The method for preparing the surface-modified bromide flame retardant according to claim 1, characterized in that, In step S1, the molar ratio of tetrabromobisphenol A glycidyl ether to 2,7-dihydroxynaphthalene in the reaction solution is 63~65:62, and the amount of cyclohexanone solvent added is 21~26% of the mass of tetrabromobisphenol A glycidyl ether.

3. The method for preparing the surface-modified bromide flame retardant according to claim 2, characterized in that, In step S1, adjusting the concentration of the reaction system during the reaction process specifically involves adding 20-24% (by mass) of tetrabromobisphenol A glycidyl ether cyclohexanone solvent to the reaction system when stirring becomes difficult.

4. The method for preparing the surface-modified bromide flame retardant according to claim 1, characterized in that, In step S2, the molar ratio of hexachlorocyclotriphosphazene, triethylamine and KH550 is 1:1:4, and the molar ratio of ethanolamine and hexachlorocyclotriphosphazene is 2~2.1:

1.

5. The method for preparing the surface-modified bromide flame retardant according to claim 4, characterized in that, In step S3, the mass of the ferric nitrate in the ethanol solution is 1 to 1.5% of the mass of the siloxane cyclotriphosphazene.

6. The method for preparing the surface-modified bromide flame retardant according to claim 5, characterized in that, In step S4, the mass ratio of the high molecular weight brominated epoxy resin flame retardant to the cyclotriphosphazene modifier is 10~20:

1.

7. The method for preparing the surface-modified bromide flame retardant according to claim 1, characterized in that, In step S1, the preparation method of the tetrabromobisphenol A glycidyl ether is as follows: Tetrabromobisphenol A and epichlorohydrin are added to a methyl isobutyl ketone solvent, heated and stirred until dissolved to form a reaction solution. While stirring, a sodium hydroxide aqueous solution with a mass concentration of 40-50% is added to the solution, and the mixture is refluxed for 3-4 hours. After the reaction is completed, methyl isobutyl ketone is added to dilute the solution. Then, while stirring, a sodium hydroxide aqueous solution with a mass concentration of 20-30% is added to the solution, and the mixture is refluxed for another 3-4 hours. After the reaction is completed, the pH of the system is adjusted to neutral, and the solution is washed three times with deionized water at 70-80°C. The organic phase is then distilled under reduced pressure to obtain tetrabromobisphenol A glycidyl ether.

8. The method for preparing the surface-modified bromide flame retardant according to claim 7, characterized in that, The molar ratio of tetrabromobisphenol A to epichlorohydrin is 1:2, the molar amount of sodium hydroxide in the 40-50% sodium hydroxide aqueous solution is 0.12-0.15 times the molar amount of tetrabromobisphenol A, and the molar amount of sodium hydroxide in the 20-30% sodium hydroxide aqueous solution is 1-1.02 times the molar amount of tetrabromobisphenol A.

9. A surface-modified bromide flame retardant, characterized in that, The surface-modified bromide flame retardant is prepared by the method described in claim 1.

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