A bio-based flame retardant-nanometer calcium carbonate, a preparation method and application thereof in epoxy resin

Abstract

The present application provides a kind of bio-based flame retardant-nano calcium carbonate, preparation method and its application in epoxy resin, the present application uses chemical synthesis reaction, preparation with vanillin, polyethylene imine, diethylene triamine and phytic acid as raw material, design multi-arm dendritic compound, combine molecular modification technology, synthesis green environmental protection biomass-based novel flame retardant Trif-V-PP with acid source, carbon source and gas source function, can enhance the flame retardant performance of epoxy resin.In addition, Trif-V-PP is combined with nano calcium carbonate, and the flame retardant performance and mechanical property of epoxy resin can be further enhanced.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin flame retardant technology, and particularly to a bio-based flame retardant—nano-calcium carbonate, its preparation method, and its application in epoxy resin. Background Technology

[0002] With the rapid development of polymer materials, they have been widely used in automobiles, home furnishings, and other fields. However, most polymer materials are flammable and will release a large amount of heat in a short period of time once burned. For example, epoxy resin (EP) has an oxygen index of only about 18%, therefore, the flame retardancy of EP is crucial.

[0003] Currently, the most widely used method to obtain flame-retardant EP composite materials is to add flame retardants. However, the raw materials for commonly used flame retardants are derived from chemical products, which leads to resource shortages. At the same time, if the added flame retardant can also participate in the curing reaction, it can further improve the mechanical properties of EP. Summary of the Invention

[0004] Therefore, the purpose of this invention is to propose a bio-based flame retardant—nano-calcium carbonate, its preparation method, and its application in epoxy resins. A chemical synthesis reaction is employed to prepare a novel, environmentally friendly biomass-based flame retardant (Trif-V-PP) using vanillin, polyethyleneimine (PEI), diethylenetriamine (DETA), and phytic acid (PA) as raw materials. Multi-armed dendritic compounds are designed and combined with molecular modification techniques to synthesize a green and environmentally friendly biomass-based flame retardant that functions as an acid source, carbon source, and gas source. To further enhance the flame retardant properties of the above-mentioned flame retardant, it is compounded with nano-calcium carbonate, which can impart superior flame retardant and mechanical properties to epoxy resins.

[0005] The technical solution of this invention is implemented as follows:

[0006] A method for preparing a bio-based flame retardant includes the following steps:

[0007] (1) Dissolve cyanuric chloride in an organic solvent, add diethylenetriamine dropwise under ice bath, react at 0~4℃ for 3~5 h, then react at room temperature for 40~55 h to obtain product 1;

[0008] (2) Dissolve vanillin in an organic solvent, add product 1, react at 50~80℃ for 6~12 h, filter, dry to obtain product 2;

[0009] (3) Dissolve product 2 in an organic solvent, heat to 70~90℃, stop heating, add polyethyleneimine dropwise, raise the temperature to 70~90℃ and react for 6~10 h, add 20~40% phytic acid solution dropwise, continue to react at 70~90℃ for 2~5 h, filter, dry, and obtain the bio-based flame retardant.

[0010] The molar ratio of cyanuric chloride to diethylenetriamine is 3-4:1;

[0011] The molar ratio of product 1 to vanillin is 1:6~8;

[0012] The molar ratio of product 2, polyethyleneimine, and phytic acid solution is 2~3:1:2~3.

[0013] Furthermore, step (1) also includes adding anhydrous sodium carbonate to cyanuric chloride, wherein the molar ratio of cyanuric chloride to anhydrous sodium carbonate is 1~2:1~2;

[0014] Step (2) also includes adding anhydrous sodium carbonate to vanillin, with a molar ratio of vanillin to anhydrous sodium carbonate of 1~2:1~2; reacting at 50~55℃ for 4~6 h, and then heating to 75~80℃ for 4~6 h.

[0015] Cyanurium chloride reacts with diethylenetriamine to produce HCl. Anhydrous sodium carbonate can be used to neutralize the HCl, which also helps the reaction proceed in the forward direction, thus improving the reaction efficiency.

[0016] Furthermore, the organic solvent is selected from tetrahydrofuran, acetone, or 1,4-dioxane.

[0017] Furthermore, in step (1), the organic solvent is tetrahydrofuran, and the mass-to-volume ratio of cyanuric chloride and tetrahydrofuran is 6~8 g: 90~120 mL;

[0018] In step (2), the organic solvent is acetone, and the mass-to-volume ratio of vanillin and acetone in the liquid is 5~7 g: 70~100 mL;

[0019] In step (3), the organic solvent is 1,4-dioxane, and the mass-to-volume ratio of product 2 and 1,4-dioxane is 0.5~2 g: 20~40 mL.

[0020] This invention provides a bio-based flame retardant prepared by the above-described method.

[0021] A bio-based flame retardant – nano-calcium carbonate, is obtained by mixing the above-mentioned bio-based flame retardant and nano-calcium carbonate.

[0022] On the one hand, the present invention also provides the application 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.

[0023] Furthermore, at 80~100℃, the bio-based flame retardant or the bio-based flame retardant-nano calcium carbonate, curing agent and epoxy resin are stirred and mixed, poured into a mold, cured at 110~130℃ for 1~2 h, the temperature is further increased to 140~160℃ for 1~2 h, and finally the temperature is increased to 170~190℃ for 1~2 h.

[0024] Furthermore, by weight, the composition includes 90-110 parts epoxy resin, 18-24 parts curing agent, and 3-6 parts bio-based flame retardant or bio-based flame retardant-nano calcium carbonate.

[0025] 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.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] This invention uses vanillin, polyethyleneimine, diethylenetriamine, and phytic acid as raw materials. Through chemical synthesis reactions, multi-armed dendritic compounds are designed and combined with molecular modification technology to synthesize a green and environmentally friendly biomass-based novel flame retardant, Trif-V-PP, which has the functions of acid source, carbon source, and gas source. It can be applied to the epoxy resin system in one step to participate in the curing reaction, which can further improve the flame retardant performance of epoxy resin.

[0028] Furthermore, combining Trif-V-PP with nano-calcium carbonate can further enhance the flame retardant and mechanical properties of epoxy resin. The prepared Trif-V-PP / nano-calcium carbonate@EP material has a peak heat release of 405 kW / m³. 2 The LOI is 28.1%, the UL-94 rating is V-0, and the tensile strength is 55.7 MPa. Attached Figure Description

[0029] Figure 1 This is a diagram illustrating the reaction process for the synthesis of FR-1(6Cl).

[0030] Figure 2 This is a diagram illustrating the reaction process for the synthesis of Trif-V.

[0031] Figure 3 Infrared spectra of FR-1(6Cl) and Trif-V;

[0032] Figure 4 The infrared spectrum of Trif-V-PP;

[0033] Figure 5 The graph shows the change in heat release rate of EP and its modified EP over time. Detailed Implementation

[0034] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0035] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0036] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0037] The cone-shaped calorific value was determined according to the test standard ISO 5660-1; the limiting oxygen index was determined according to the test standard ISO 4589-2; and the horizontal and vertical combustion values ​​were determined according to the test standard ISO 9773–1998.

[0038] Example 1

[0039] The preparation method of the bio-based flame retardant Trif-V-PP is as follows:

[0040] 1. Synthesis of FR-1(6Cl)

[0041] (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) into a 250 mL three-necked flask, add 100 mL THF (tetrahydrofuran), and stir with a magnetic stirrer to dissolve.

[0042] (2) 1.0317 g (0.01 mol) of EDTA solution was slowly added dropwise to the above solution under ice bath conditions, and the temperature was controlled at 0-2℃ for 4 h, followed by reaction at room temperature for 48 h.

[0043] (3) After the reaction was completed, the filter cake was washed with deionized water until neutral and dried for 24 h to obtain the white product FR-1(6Cl).

[0044] The reaction process for the synthesis of FR-1(6Cl) is as follows: Figure 1 As shown.

[0045] 2. Synthesis of Trif-V

[0046] (1) Weigh 6.465 g vanillin (0.0425 mol) and 4.505 g anhydrous sodium carbonate (0.0425 mol) and dissolve them in 80 mL of acetone. Stir at room temperature for 0.5 h.

[0047] (2) Add 3.4 g (0.0062 mol) of FR-1 (6Cl) to the above solution, heat to 50℃ and react for 4 h, then heat to 80℃ and react for 4 h.

[0048] (3) After the reaction is complete, cool to room temperature and filter to obtain crude product. Wash crude product with deionized water three times and finally dry it in an oven for 24 h to obtain white powder product Trif-V.

[0049] The reaction process of Trif-V is as follows: Figure 2 As shown.

[0050] Depend on Figure 3 It can be seen that the C-Cl bond peak in TCT is located at 1269 cm⁻¹. -1 and 848cm -1 The characteristic peaks of CN and the triazine ring are located at 1359 cm⁻¹, while those of CN and the triazine ring are located at 1359 cm⁻¹. -1 and 1497cm -1 In the infrared spectrum of vanillin, the characteristic peaks of the OH bond and the -CH=O bond are located at 3170 cm⁻¹. -1 and 1665cm -1 It can be observed at [location missing]. In the Trif-V infrared spectrum, no characteristic peaks of OH (from vanillin) and C-Cl (from TCT) were detected, indicating that the starting material had reacted sufficiently. Furthermore, characteristic peaks were observed at 1668, 1588, 1448, and 1338 cm⁻¹. -1 Similar peaks were found at the location, and these characteristic peaks were attributed to the -CH=O bond, the triazine ring, and the CN bond, respectively.

[0051] 3. Synthesis of Trif-V-PP

[0052] n(Trif-V):n(PEI):n(30%PA)=2:1:2

[0053] (1) Weigh 1.192 g Trif-V and measure 30 mL of 1,4-dioxane into a 50 mL double-necked flask and heat to 80 °C;

[0054] (2) Stop heating and slowly add PEI dropwise into the flask, adding 0.3 g;

[0055] (3) After the addition is complete, the temperature is raised to 80℃ and the reaction is carried out for 8 hours;

[0056] (4) Prepare a 30% PA solution from a 70% PA solution, add 0.33g of the solution to the above reaction solution, and react at 80°C for 3 h;

[0057] (5) After the reaction is complete, filter, wash with water, and dry in an oven to obtain the final product Trif-V-PP.

[0058] Depend on Figure 4 It can be seen that the characteristic peaks of the -CH=O bond do not appear in the infrared spectrum of Trif-V-PP. Instead, peaks can be observed at 1667, 1654, and 1448 cm⁻¹. -1 The three new bands are primary amine (NH2 group), C=N (aliphatic) and NH3. + The characteristic peaks of the •ˉO-P group. In summary, these results indicate that Trif-V, PEI, and PA react with each other via Schiff base reactions and ionic bonds to form Trif-V-PP. Simultaneously, CN and the triazine ring, CH (2954 and 2839 cm⁻¹) are also observed. -1 ) and PO (1030cm) -1 All three are present in Trif-V-PP, originating from Trif-V, PEI, and PA, respectively. 1667cm -1 The peak at that position is a characteristic peak of the NH2 group, indicating that a small amount of primary amine does not react with PA.

[0059] Example 2

[0060] Trif-V-PP and nano-calcium carbonate were incorporated into epoxy resin (EP) in a specific ratio: 100 parts epoxy resin, 21.4 parts curing agent, and 5 parts dopant. First, epoxy resin was added to a three-necked flask and heated to 90°C to bring it to a fluid state. Then, DOPO@VC and nano-calcium carbonate were added and mixed thoroughly. Next, 4,4'-diaminodiphenylmethane curing agent was added and mixed again thoroughly. The mixture was then poured into a preheated PTFE sheet. After completion, the flask was placed in a vacuum drying oven and heated to 120°C for 2 hours, then further heated to 150°C for 2 hours, and finally heated to 180°C for 1 hour. The cured composite epoxy resin sample was then removed while still hot. The reaction raw material ratio is as follows:

[0061] Table 1. Raw material ratio of EP composite material

[0062]

[0063] The flame retardant performance results are as follows, based on experimental testing. Figure 5 (Cone calorimetric heat release value) is shown in Table 2, which contains the cone calorimetric heat release value, limiting oxygen index (LOI) value, horizontal and vertical flammability value (UL-94) and mechanical property values.

[0064] Table 2. Key data related to the flame retardant and mechanical properties of EP and its modified EP.

[0065]

[0066] As shown in Table 2, the peak heat release of the prepared Trif-V-PP@EP material is 767 kW / m. 2 The LOI was 24.5%, the UL-94 rating was V-1, and the tensile strength was 52.7 MPa. The peak heat release of the prepared Trif-V-PP / nano-calcium carbonate@EP material was 405 kW / m³. 2 The LOI is 28.1%, the UL-94 rating is V-0, and the tensile strength is 55.7 MPa. The flame retardant 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 and mechanical properties of the modified EP material.

[0067] Example 3

[0068] Based on Example 1, in the synthesis of FR-1(6Cl), the molar ratio of TCT:DETA:anhydrous sodium carbonate was adjusted to 3:1:3 to synthesize FR-1(6Cl). Subsequent steps were the same as in Example 1, and the final product Trif-V-PP was obtained. The application effect was consistent with that in Example 1.

[0069] Example 4

[0070] Based on 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 to 8, and the reaction conditions were adjusted within the range of 50 to 55℃ for 4 to 6 h, followed by heating to 75 to 80℃ for 4 to 6 h. Trif-V could be synthesized in both cases. The remaining steps were the same as in Example 1, and the final product Trif-V-PP was obtained. The application effect was the same as in Example 1.

[0071] 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 within the protection scope of the present invention.

Claims

1. A process for the preparation of a bio-based flame retardant-nanocalcium carbonate, characterized by, The bio-based flame retardant-nano calcium carbonate comprises a bio-based flame retardant and nano calcium carbonate mixed together, and a preparation method of the bio-based flame retardant comprises the following steps: (1) cyanuric chloride is dissolved into an organic solvent, diethylenetriamine is added dropwise under ice bath, after reaction at 0-4 ℃ for 3-5 h and reaction at normal temperature for 40-55 h, product 1 is obtained; (2) vanillin is dissolved into an organic solvent, product 1 is added, and reaction is carried out at 50-80 ℃ for 6-12 h, then filtration and drying are carried out to obtain product 2; (3) product 2 is dissolved into an organic solvent, heating is carried out to 70-90 ℃, then heating is stopped, polyethyleneimine is added dropwise, heating is carried out to 70-90 ℃ for 6-10 h, a 20-40% mass concentration phytic acid solution is added dropwise, and reaction is continuously carried out at 70-90 ℃ for 2-5 h, then filtration and drying are carried out to obtain the bio-based flame retardant; The molar ratio of cyanuric chloride and diethylenetriamine is 3-4:1; The molar ratio of product 1 and vanillin is 1:6-8; The molar ratio of product 2, polyethyleneimine and phytic acid solution is 2-3:1:2-3; In step (2), anhydrous sodium carbonate is further added to vanillin, the molar ratio of vanillin and anhydrous sodium carbonate is 1-2:1-2, reaction is carried out at 50-55 ℃ for 4-6 h, then heating is carried out to 75-80 ℃ for 4-6 h.

2. A process for the preparation of a bio-based flame retardant-nanocalcium carbonate according to claim 1, characterized by, In step (1), anhydrous sodium carbonate is further added to cyanuric chloride, the molar ratio of cyanuric chloride and anhydrous sodium carbonate is 1-2:1-2.

3. A process for the preparation of a bio-based flame retardant-nanocalcium carbonate according to claim 1, characterized by, The organic solvent is selected from one of tetrahydrofuran, acetone or 1,4-dioxane.

4. A process for the preparation of a bio-based flame retardant-nanocalcium carbonate according to claim 3, characterized by, In step (1), the organic solvent is tetrahydrofuran, the mass-volume ratio of cyanuric chloride and tetrahydrofuran is 6-8 g:90-120 mL; In step (2), the organic solvent is acetone, the mass-volume ratio of vanillin and acetone is 5-7 g:70-100 mL; In step (3), the organic solvent is 1,4-dioxane, the mass-volume ratio of 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 the bio-based flame retardant-nano calcium carbonate in any one of claims 1-4.

6. An application of the bio-based flame retardant-nano calcium carbonate in claim 5 in improving the flame retardant performance and / or tensile strength of an epoxy resin.

7. Use according to claim 6, characterized in that, The bio-based flame retardant-nano calcium carbonate, a curing agent and an epoxy resin are stirred and mixed at 80-100 ℃, poured into a mold, cured at 110-130 ℃ for 1-2 h, continuously heated to 140-160 ℃ for 1-2 h, and finally heated to 170-190 ℃ for 1-2 h.

8. Use according to claim 7, characterized in that, 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 by weight.

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