Bio-based flame retardant-nano calcium carbonate, preparation method and application of bio-based flame retardant-nano calcium carbonate in epoxy resin

Abstract

According to the bio-based flame retardant-nano calcium carbonate, a chemical synthesis reaction is adopted, vanillin, polyethyleneimine, diethylenetriamine, phytic acid and the like are used as raw materials, a multi-arm dendritic compound is designed, a molecular modification technology is combined, and the bio-based flame retardant-nano calcium carbonate is prepared. The green and environment-friendly biomass-based novel flame retardant Trif-V-PP with the functions of an acid source, a carbon source and a gas source is synthesized, and the flame retardant property of epoxy resin can be enhanced. In addition, the Trif-V-PP is combined with the nano calcium carbonate, so that the flame retardant property and the mechanical property of the epoxy resin can be further enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resin flame retardants, and in particular to a bio-based flame retardant-nano calcium carbonate, a preparation method and application thereof in epoxy resins. Background Art

[0002] With the rapid development of polymer materials, they have found widespread application in areas such as automobiles and home furnishings. However, most polymer materials are flammable and, once burned, release a large amount of heat in a short period of time. For example, epoxy resin (EP) has an oxygen index of only around 18%, making flame retardancy crucial.

[0003] At present, adding flame retardants is one of the most widely used methods to effectively obtain flame-retardant EP composite materials. However, the raw materials of commonly used flame retardants are derived from chemical products, which leads to resource shortages. At the same time, if the added flame retardants can also participate in the curing reaction, the mechanical properties of EP can be further improved. Summary of the Invention

[0004] In light of this, the present invention aims to develop a bio-based flame retardant—nano-calcium carbonate—as well as its preparation method and application in epoxy resins. Using chemical synthesis, a multi-arm dendrimer is designed using vanillin, polyethyleneimine (PEI), diethylenetriamine (DETA), and phytic acid (PA) as raw materials. Combined with molecular modification techniques, this novel, green and environmentally friendly biomass-based flame retardant (Trif-V-PP) is synthesized as a single acid, carbon, and gas source. To further enhance the flame retardancy of this flame retardant, its combination with nano-calcium carbonate imparts superior flame retardancy and mechanical properties to epoxy resins.

[0005] The technical solution of the present invention is achieved as follows: A method for preparing a bio-based flame retardant comprises the following steps: (1) Dissolve cyanuric chloride in an organic solvent, add diethylenetriamine dropwise in an ice bath, react at 0-4°C for 3-5 h, and then react at room temperature for 40-55 h to obtain product 1; (2) Dissolve vanillin in an organic solvent, add product 1, react at 50-80°C for 6-12 h, filter, and dry to obtain product 2; (3) dissolving the product 2 in an organic solvent, heating to 70-90°C, stopping heating, adding polyethyleneimine dropwise, raising the temperature to 70-90°C and reacting for 6-10 h, adding a phytic acid solution with a mass concentration of 20-40%, continuing to react at 70-90°C for 2-5 h, filtering, and drying to obtain the bio-based flame retardant; The molar ratio of cyanuric chloride to diethylenetriamine is 3 to 4:1; The molar ratio of the product 1 to vanillin is 1:6-8; The molar ratio of the product 2, polyethyleneimine and phytic acid solution is 2-3:1:2-3.

[0006] Furthermore, in step (1), anhydrous sodium carbonate is added to cyanuric chloride, and the molar ratio of cyanuric chloride to anhydrous sodium carbonate is 1-2:1-2; Step (2) further includes adding anhydrous sodium carbonate to vanillin, with the molar ratio of vanillin to anhydrous sodium carbonate being 1-2:1-2; reacting at 50-55°C for 4-6 hours, and then heating to 75-80°C for 4-6 hours.

[0007] Cyanuric chloride reacts with diethylenetriamine to produce HCl. Anhydrous sodium carbonate can be used to neutralize the HCl, and it is also beneficial for the reaction to proceed toward a positive reaction, thereby improving the reaction efficiency.

[0008] Furthermore, the organic solvent is selected from one of tetrahydrofuran, acetone or 1,4-dioxane.

[0009] Furthermore, in step (1), the organic solvent is tetrahydrofuran, and the mass volume ratio of cyanuric chloride to tetrahydrofuran is 6-8 g:90-120 mL; In step (2), the organic solvent is acetone, and the mass volume ratio of vanillin to acetone is 5-7 g:70-100 mL; In step (3), the organic solvent is 1,4-dioxane, and the mass volume ratio of the product 2 and 1,4-dioxane is 0.5~2 g: 20~40 mL.

[0010] The present invention provides a bio-based flame retardant prepared by the above-mentioned method for preparing a bio-based flame retardant.

[0011] A bio-based flame retardant-nano calcium carbonate is obtained by mixing the above-mentioned bio-based flame retardant and nano calcium carbonate.

[0012] On the one hand, the present invention also provides a use of the above-mentioned bio-based flame retardant or the above-mentioned bio-based flame retardant-nano calcium carbonate in improving the flame retardant properties and / or tensile strength of epoxy resin.

[0013] Furthermore, the bio-based flame retardant or the bio-based flame retardant-nano calcium carbonate, a curing agent and an epoxy resin are stirred and mixed at 80-100° C., poured into a mold, and cured at 110-130° C. for 1-2 h, then heated to 140-160° C. for 1-2 h, and finally heated to 170-190° C. for 1-2 h.

[0014] Furthermore, by weight, the epoxy resin is 90-110 parts, the curing agent is 18-24 parts, and the bio-based flame retardant or bio-based flame retardant-nano calcium carbonate is 3-6 parts.

[0015] On the other hand, the present invention also provides a flame-retardant epoxy resin material, which is obtained by curing the above-mentioned bio-based flame retardant or the above-mentioned bio-based flame retardant-nano calcium carbonate in an epoxy resin system.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses vanillin, polyethyleneimine, diethylenetriamine and phytic acid as raw materials, designs multi-arm dendritic compounds through chemical synthesis reactions, and combines molecular modification technology to synthesize a green and environmentally friendly biomass-based new flame retardant Trif-V-PP with the functions of acid source, carbon source and gas source. The compound is then applied in a one-step manner to an epoxy resin system to participate in the curing reaction, thereby further improving the flame retardant properties of the epoxy resin.

[0017] In addition, the combination of Trif-V-PP and nano-calcium carbonate can further enhance the flame retardancy and mechanical properties of epoxy resin. The heat release peak of the prepared Trif-V-PP / nano-calcium carbonate@EP material is 405 kW / m 2 , LOI is 28.1%, UL-94 is V-0 level, and tensile strength is 55.7 Mpa. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the reaction process diagram for the synthesis of FR-1(6Cl); Figure 2 This is a reaction process diagram for the synthesis of Trif-V; Figure 3 The infrared spectra of FR-1(6Cl) and Trif-V are shown; Figure 4 is the infrared spectrum of Trif-V-PP; Figure 5 This is a graph showing the heat release rate of EP and its modified EP changing with time. DETAILED DESCRIPTION

[0019] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0020] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0021] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0022] Cone calorimetry is performed according to ISO 5660-1; limiting oxygen index is performed according to ISO 4589-2; and horizontal and vertical burning values are performed according to ISO 9773–1998.

[0023] Example 1 The preparation method of the bio-based flame retardant Trif-V-PP is as follows: 1. Synthesis of FR-1(6Cl) (1) n(cyanuric chloride, TCT):n(diethylenetriamine, DETA):n(anhydrous sodium carbonate) = 4:1:4. Weigh 7.3764 g TCT (0.04 mol) and 4.2396 g anhydrous sodium carbonate (0.04 mol) and place them in a 250 mL three-necked flask. Add 100 mL THF (tetrahydrofuran) and stir with a magnetic stirrer to dissolve.

[0024] (2) Slowly drop 1.0317 g (0.01 mol) of EDTA solution into the above solution under ice bath, control the temperature at 0-2°C to react for 4 h, and then react at room temperature for 48 h.

[0025] (3) After the reaction is completed, the filter cake is filtered and washed with deionized water until it is neutral. After drying for 24 h, the white product FR-1(6Cl) is obtained.

[0026] The reaction process of FR-1(6Cl) synthesis is as follows Figure 1 shown.

[0027] 2. Synthesis of Trif-V (1) Weigh 6.465 g of vanillin (0.0425 mol) and 4.505 g of anhydrous sodium carbonate (0.0425 mol) and dissolve them in 80 mL of acetone. Stir at room temperature for 0.5 h.

[0028] (2) Add 3.4 g (0.0062 mol) of FR-1(6Cl) to the above solution, heat to 50°C and react for 4 h, then heat to 80°C and react for 4 h.

[0029] (3) After the reaction is completed, the mixture is cooled to room temperature and filtered to obtain a crude product. The crude product is washed with deionized water three times and finally dried in an oven for 24 h to obtain a white powder product, Trif-V.

[0030] The reaction process of Trif-V is as follows Figure 2 shown.

[0031] Depend on Figure 3 It can be seen that the C-Cl bond peak in TCT is located at 1269 cm -1 and 848cm -1 The characteristic peaks of CN and triazine ring are located at 1359 cm -1 and 1497cm -1 In the infrared spectrum of vanillin, the characteristic peaks of OH bond and -CH=O bond are at 3170 cm -1 and 1665cm -1 In the infrared spectrum of Trif-V, no characteristic peaks of OH (from vanillin) and C-Cl (from TCT) were detected, which indicated that the raw materials had been fully reacted. In addition, the peaks at 1668, 1588, 1448 and 1338 cm -1 Similar peaks were found at , and these characteristic peaks were attributed to the -CH=O bond, triazine ring and CN bond, respectively.

[0032] 3. Synthesis of Trif-V-PP n(Trif-V):n(PEI):n(30%PA)=2:1:2 (1) Weigh 1.192 g of Trif-V and 30 mL of 1,4-dioxane into a 50 mL two-necked flask and heat to 80°C. (2) Stop heating and slowly add 0.3 g of PEI into the flask; (3) After the addition is complete, heat to 80°C and react for 8 h; (4) Prepare a 30% PA solution by adding 70% PA solution to the above reaction solution, and react at 80°C for 3 h. (5) After the reaction is completed, the product is filtered, washed with water, and dried in an oven to obtain the final product Trif-V-PP.

[0033] Depend on Figure 4 It can be seen that the characteristic peak of -CH=O bond does not appear in the infrared spectrum of Trif-V-PP. Instead, the peaks at 1667, 1654 and 1448 cm -1 The three new bands are primary amine (NH2 group), C=N (aliphatic) and NH3 + •ˉ Characteristic peaks of O-P groups. In summary, these results indicate that Trif-V, PEI, and PA react with each other through Schiff base reaction and ionic bonding to form Trif-V-PP. At the same time, CN and triazine ring, CH (2954 and 2839 cm -1) and PO (1030cm -1 ) are present in Trif-V-PP and come from Trif-V, PEI and PA respectively. 1667cm -1 The peak at is the characteristic peak of NH2 group, indicating that a small amount of primary amine does not react with PA.

[0034] Example 2 The prepared Trif-V-PP and nano-calcium carbonate are doped into EP in a certain proportion, with the ratio being: 100 parts epoxy resin, 21.4 parts curing agent, and 5 parts doping raw materials. First, add the epoxy resin to a three-necked flask and heat it to 90°C to make the epoxy resin in a fluid state. Then add DOPO@VC and nano-calcium carbonate, mix and stir evenly, add the curing agent 4,4'-diaminodiphenylmethane, stir thoroughly again, and pour into the preheated polytetrafluoroethylene sheet. After completion, place it in a vacuum drying oven, heat it to 120°C for 2 hours, then continue to heat it to 150°C for 2 hours, and finally heat it to 180°C for 1 hour. Take out the cured composite epoxy resin sample while it is hot. The reaction raw material ratio is as follows: Table 1 EP composite material raw material ratio

[0035] After experimental testing, the flame retardant performance results are as follows Figure 5 (Cone calorimetry heat release value), Table 2 shows the cone calorimetry heat release value, limiting oxygen index value (LOI), horizontal vertical burning value (UL-94) and mechanical property value.

[0036] Table 2 Core data related to flame retardancy and mechanical properties of EP and its modified EP

[0037] As shown in Table 2, the peak heat release of the prepared Trif-V-PP@EP material is 767 kW / m 2 , LOI is 24.5%, UL-94 is V-1 level, and tensile strength is 52.7 Mpa; the heat release peak of the prepared Trif-V-PP / nano-calcium carbonate@EP material is 405 kW / m 2 , LOI is 28.1%, UL-94 is V-0 level, and tensile strength is 55.7 Mpa; the flame retardant properties and mechanical properties of the modified EP material are improved to varying degrees. Combining Trif-V-PP with nano-calcium carbonate further enhances the flame retardant properties and mechanical properties of the modified EP material.

[0038] Example 3 On the basis of Example 1, in the synthesis of FR-1(6Cl), the molar ratio of TCT:DETA:anhydrous sodium carbonate was adjusted to 3:1:3, and FR-1(6Cl) was synthesized. The subsequent steps were the same as in Example 1 to obtain the final product Trif-V-PP, and the application effect was consistent with that in Example 1.

[0039] Example 4 On the basis of Example 1, in the synthesis of Trif-V, the molar ratio of FR-1(6Cl) to vanillin was adjusted within the range of 1:6-8, and the reaction conditions were adjusted within the range of 50-55°C for reaction for 4-6 h and then raised to 75-80°C for reaction for 4-6 h. Trif-V can be synthesized. The remaining steps are the same as in Example 1 to obtain the final product Trif-V-PP, and the application effect is consistent with that of Example 1.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a bio-based flame retardant-nano calcium carbonate, characterized in that: The bio-based flame retardant-nano calcium carbonate comprises a mixture of a bio-based flame retardant and nano calcium carbonate. The preparation method of the bio-based flame retardant comprises the following steps: (1) Dissolve cyanuric chloride in an organic solvent, add diethylenetriamine dropwise in an ice bath, react at 0-4°C for 3-5 h, and then react at room temperature for 40-55 h to obtain product 1; (2) Dissolve vanillin in an organic solvent, add product 1, react at 50-80°C for 6-12 h, filter, and dry to obtain product 2; (3) dissolving the product 2 in an organic solvent, heating to 70-90°C, stopping heating, adding polyethyleneimine dropwise, raising the temperature to 70-90°C and reacting for 6-10 h, adding a phytic acid solution with a mass concentration of 20-40%, continuing to react at 70-90°C for 2-5 h, filtering, and drying to obtain the bio-based flame retardant; The molar ratio of cyanuric chloride to diethylenetriamine is 3 to 4:1; The molar ratio of the product 1 to vanillin is 1:6-8; The molar ratio of the product 2, polyethyleneimine and phytic acid solution is 2-3:1:2-3.

2. The method for preparing a bio-based flame retardant-nano calcium carbonate according to claim 1, characterized in that: In step (1), anhydrous sodium carbonate is added to cyanuric chloride, and the molar ratio of cyanuric chloride to anhydrous sodium carbonate is 1-2:1-2; Step (2) further includes adding anhydrous sodium carbonate to vanillin, with the molar ratio of vanillin to anhydrous sodium carbonate being 1-2:1-2; reacting at 50-55°C for 4-6 hours, and then heating to 75-80°C for 4-6 hours.

3. The method for preparing a bio-based flame retardant-nano calcium carbonate according to claim 1, characterized in that: The organic solvent is selected from one of tetrahydrofuran, acetone or 1,4-dioxane.

4. The method for preparing a bio-based flame retardant-nano calcium carbonate according to claim 3, characterized in that: In step (1), the organic solvent is tetrahydrofuran, and the mass volume ratio of cyanuric chloride to tetrahydrofuran is 6-8 g:90-120 mL; In step (2), the organic solvent is acetone, and the mass volume ratio of vanillin to acetone is 5-7 g:70-100 mL; In step (3), the organic solvent is 1,4-dioxane, and the mass volume ratio of the product 2 and 1,4-dioxane is 0.5~2 g: 20~40 mL.

5. The bio-based flame retardant-nano calcium carbonate prepared by the preparation method of a bio-based flame retardant-nano calcium carbonate according to any one of claims 1 to 4.

6. Use of the bio-based flame retardant nano-calcium carbonate according to claim 5 in improving the flame retardancy and / or tensile strength of epoxy resin.

7. The use according to claim 6, characterized in that The bio-based flame retardant (nano calcium carbonate), curing agent and epoxy resin are stirred and mixed at 80-100°C, poured into a mold, and cured at 110-130°C for 1-2 hours, then heated to 140-160°C for 1-2 hours, and finally heated to 170-190°C for 1-2 hours.

8. The use according to claim 7, characterized in that By weight, the epoxy resin is 90-110 parts, the curing agent is 18-24 parts, and the bio-based flame retardant - nano calcium carbonate is 3-6 parts.

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