Fireproof composite material and preparation method thereof

Abstract

The application discloses a fireproof composite material and a preparation method thereof, and belongs to the technical field of high polymer materials. The fireproof composite material comprises the following raw materials in parts by weight: 60-80 parts of epoxy resin, 20-30 parts of silicon dioxide, 10-18 parts of a flame retardant, 10-15 parts of a curing agent, 2-5 parts of a toughening agent, 1-2 parts of an accelerator and 1-3 parts of an antioxidant. The toughening agent is prepared by reacting trimesic acid with oleyl alcohol to generate a triester compound, reacting 1,4-benzene diboronic acid with 3-mercapto-1,2-propanediol to generate a dioxaborine compound, and reacting the triester compound with the dioxaborine compound. The fireproof composite material prepared by the application has good flame retardant performance and impact resistance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a fire-resistant composite material and its preparation method. Background Technology

[0002] In recent years, with the rapid development of science and technology, polymer composite materials have become increasingly common in our daily lives. While these products have brought us many conveniences, the potential dangers they pose cannot be ignored. Most polymer materials are flammable, and we must attach great importance to the safe use of polymer products and take effective measures to prevent fire accidents. Epoxy resin (EP), due to its excellent adhesion, heat and moisture resistance, corrosion resistance, and easy processing properties, has been widely used in adhesives, automotive machinery, material repair, aerospace, and other fields. However, its high crosslinking density easily leads to brittle fracture, and its inherent flammability limits its further promotion in certain application areas. To overcome these shortcomings, researchers have been exploring modifications to improve the toughness and flame retardancy of epoxy resins.

[0003] Chinese invention patent CN105694370A discloses a toughened-flame-retardant epoxy resin material and its preparation method. This toughened epoxy resin material comprises epoxy resin monomers, a curing agent, expanded graphite, and flame-retardant microcapsules. By weight fraction, the epoxy resin monomers comprise 70-95 parts, the flame-retardant microcapsules 5-25 parts, the curing agent 10-30 parts, and the expanded graphite 0.3-1 parts, cured at 100-220℃. The flame-retardant microcapsules are prepared using ammonium polyphosphate with a molecular weight greater than 1500 as the core and a benzoxazine cross-linked network as the shell. This invention discloses a toughened-flame-retardant epoxy resin material that simultaneously improves the material's toughness and flame-retardant properties, effectively compensating for the shortcomings of improving only one property of the material. However, its mechanical properties need further improvement. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a fire-resistant composite material and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A fire-resistant composite material comprising the following raw materials in parts by weight:

[0007] Epoxy resin: 60-80 parts, silica: 20-30 parts, flame retardant: 10-18 parts, curing agent: 10-15 parts, toughening agent: 2-5 parts, accelerator: 1-2 parts, antioxidant: 1-3 parts;

[0008] The toughening agent is prepared by the following method:

[0009] S1: Tristyric acid reacts with oleyl alcohol to form a trimeryl compound; the reaction equation is shown below.

[0010] ;

[0011] S2: 1,4-Phenylated boric acid reacts with 3-mercapto-1,2-propanediol to form a dioxaboronic heterocyclic compound; the reaction equation is shown below:

[0012] ;

[0013] S3: The reaction of the ester compound with the dioxaboronic heterocyclic compound generates a toughening agent; in this reaction, the thiol in the dioxaboronic heterocyclic compound undergoes an addition reaction with the carbon-carbon double bond in the ester compound to generate a hyperbranched polymer.

[0014] In step S1, the molar ratio of pyromellitic acid and oleyl alcohol is 1:(3-3.5).

[0015] In step S2, the molar ratio of 1,4-phenylenediboric acid and 3-mercapto-1,2-propanediol is 1:(2-2.5).

[0016] In step S3, the molar ratio of the trimeryl compound and the dioxaboronic heterocyclic compound is (1.5-1.8):3.

[0017] The flame retardant is prepared by the following method:

[0018] N1: 4,4'-Diaminodiphenyl ether reacts with phenylphosphonic dichloride to form a linear polymer; the reaction equation is shown below:

[0019] ;

[0020] N2: A linear polymer reacts with γ-chloropropyltrimethoxysilane to form a flame retardant; the reaction equation is shown below.

[0021] ;

[0022] In step N1, the molar ratio of 4,4'-diaminodiphenyl ether to phenylphosphonic dichloride is 1.2:1; in step N2, the mass ratio of the linear polymer to γ-chloropropyltrimethoxysilane is 20:1.

[0023] The curing agent is one of diethylenetriamine and aminoethylpiperazine.

[0024] The accelerator is one of 2-methylimidazole and 2-ethyl-4-methylimidazole.

[0025] The antioxidant is one of antioxidant 1010 and antioxidant 1076.

[0026] A method for preparing a fire-resistant composite material includes the following steps:

[0027] (1) Weigh by weight: epoxy resin: 60-80 parts, silica: 20-30 parts, flame retardant: 10-18 parts, curing agent: 10-15 parts, toughening agent: 2-5 parts, accelerator: 1-2 parts, antioxidant: 1-3 parts;

[0028] (2) Stir the epoxy resin, silica, flame retardant, toughening agent and antioxidant evenly, add curing agent and accelerator and stir, heat and cure to obtain fireproof composite material.

[0029] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:

[0030] (1) The toughening agent prepared in this application has a hyperbranched structure containing benzene rings, alkyl chains and dynamic borate ester bonds, which can significantly improve the impact resistance of fireproof composite materials.

[0031] (2) The flame retardant prepared in this application improves the flame retardant performance of fireproof composite materials through active free radical capture, dehydration to char formation, release of non-flammable gases and formation of surface heat-insulating carbon layer. Detailed Implementation

[0032] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0033] Example 1: Preparation of toughening agent:

[0034] S1: 500 ml toluene, 0.1 mol trimesic acid, 0.3 mol oleyl alcohol, and 2 g p-toluenesulfonic acid were added sequentially to a reaction flask, stirred and mixed, heated to 80 °C, and reacted for 15 h (during which time the water produced in the reaction was separated using a water separator). The mixture was cooled to room temperature, the pH was adjusted to 7 using 1 M NaOH solution, and the layers were allowed to separate. The mixture was washed three times with deionized water (300 ml each time), dried over 30 g anhydrous magnesium sulfate, filtered, and distilled under reduced pressure at 80 °C for 2 h to obtain the trimeryl compound; its 1H NMR data are as follows: 1 H NMR (300 MHz, Chloroform- d) δ 8.66 (s, 3H), 5.45 (dddd, J = 5.5, 4.4, 2.1, 1.0Hz, 6H), 4.35 (t, J = 6.1 Hz, 6H), 2.10 - 1.96 (m, 12H), 1.86 - 1.71 (m, 6H),1.50 - 1.36 (m, 6H), 1.36 - 1.20 (m, 60H), 0.95 - 0.83 (m, 9H);

[0035] S2: 400 ml tetrahydrofuran, 0.6 g deionized water, 0.2 mol 3-mercapto-1,2-propanediol, and 0.1 mol 1,4-phenyldiboronic acid were sequentially added to a reaction flask and stirred for 10 min. 40 g magnesium sulfate was then added, and the mixture was stirred at room temperature for 20 h. The mixture was filtered, and then distilled under reduced pressure at 40 °C for 3 h to obtain a dioxaboronic heterocyclic compound. Its 1H NMR spectrum data are as follows: 1 H NMR (300 MHz, Chloroform- d ) δ 7.70 (s, 4H), 4.61 (tt, J = 4.3, 3.4 Hz, 2H), 4.50 (dd, J = 10.4, 3.4Hz, 2H), 4.24 (dd, J = 10.4, 3.4 Hz, 2H), 2.77 (ddd, J = 12.1, 6.1, 4.3 Hz, 2H), 2.52 (ddd, J = 12.2, 6.2, 4.2 Hz, 2H), 1.73 (d, J = 12.4 Hz, 2H);

[0036] S3: Add 1200ml of anhydrous tetrahydrofuran, 0.15mol of a trimer compound, 0.3mol of a dioxaborane heterocyclic compound, and 5g of photoinitiator 184 to a reaction flask in sequence, stir and mix well, irradiate with 385nm ultraviolet light at room temperature for 4min, and then distill under reduced pressure at 40℃ for 2h to obtain the toughening agent.

[0037] Example 2: Preparation of toughening agent:

[0038] S1: 500 ml toluene, 0.1 mol trimesic acid, 0.33 mol oleyl alcohol and 2 g p-toluenesulfonic acid were added sequentially to a reaction flask, stirred and mixed, heated to 90 °C, and reacted for 12 h (during which water generated in the reaction was separated by a water separator). After cooling to room temperature, the pH was adjusted to 7 with 1 M NaOH solution, and the mixture was allowed to stand and separate into layers. The mixture was washed three times with deionized water (300 ml each time), dried with 30 g anhydrous magnesium sulfate, filtered, and distilled under reduced pressure at 80 °C for 2 h to obtain the trimeryl compound.

[0039] S2: 400 ml tetrahydrofuran, 0.6 g deionized water, 0.23 mol 3-mercapto-1,2-propanediol and 0.1 mol 1,4-phenyldiboronic acid were added sequentially to a reaction flask and stirred for 10 min. Then, 40 g magnesium sulfate was added and stirred at room temperature for 25 h. The mixture was filtered and distilled under reduced pressure at 40 °C for 3 h to obtain a dioxaboronic heterocyclic compound.

[0040] S3: Add 1200ml of anhydrous tetrahydrofuran, 0.16mol of a trimer compound, 0.3mol of a dioxaborane heterocyclic compound, and 5g of photoinitiator 184 to a reaction flask in sequence, stir and mix well, irradiate with 385nm ultraviolet light at room temperature for 8min, and then distill under reduced pressure at 40℃ for 2h to obtain the toughening agent.

[0041] Example 3: Preparation of toughening agent:

[0042] S1: 500 ml toluene, 0.1 mol trimesic acid, 0.35 mol oleyl alcohol and 2 g p-toluenesulfonic acid were added sequentially to a reaction flask, stirred and mixed, heated to 95 °C, and reacted for 10 h (during which water generated in the reaction was separated by a water separator). After cooling to room temperature, the pH was adjusted to 7 with 1 M NaOH solution, and the mixture was allowed to stand and separate into layers. The mixture was washed three times with deionized water (300 ml each time), dried with 30 g anhydrous magnesium sulfate, filtered, and distilled under reduced pressure at 80 °C for 2 h to obtain the trimeryl compound.

[0043] S2: 400 ml tetrahydrofuran, 0.6 g deionized water, 0.25 mol 3-mercapto-1,2-propanediol and 0.1 mol 1,4-phenyldiboronic acid were added sequentially to a reaction flask and stirred for 10 min. Then, 40 g magnesium sulfate was added and stirred at room temperature for 20 h. The mixture was filtered and distilled under reduced pressure at 40 °C for 3 h to obtain a dioxaboronic heterocyclic compound.

[0044] S3: Add 1200ml of anhydrous tetrahydrofuran, 0.18mol of a trimer compound, 0.3mol of a dioxaborane heterocyclic compound, and 5g of photoinitiator 184 to a reaction flask in sequence, stir and mix well, irradiate with 385nm ultraviolet light at room temperature for 8min, and then distill under reduced pressure at 40℃ for 2h to obtain the toughening agent.

[0045] Example 4: Preparation of flame retardant:

[0046] N1: Add 400 ml DMF and 0.12 mol 4,4'-diaminodiphenyl ether to a reaction flask, stir and mix for 20 min, add 60 ml DMF solution containing 0.1 mol phenylphosphonic dichloride dropwise, and add the solution dropwise over 1 h. Heat to 90 °C and react for 6 h. Remove the generated HCl by passing a nitrogen stream through the reaction flask, cool to room temperature, distill under reduced pressure at 80 °C for 3 h, and dry under vacuum at 80 °C for 24 h to obtain the linear polymer.

[0047] N2: Under ice bath conditions, 1000 ml of anhydrous toluene, 10 g of γ-chloropropyltrimethoxysilane, 200 g of linear polymer, 0.15 mol of potassium carbonate, and 1 g of potassium iodide were added sequentially to a reaction flask. Under nitrogen protection, the mixture was heated to 80 °C and reacted for 24 h. After cooling to room temperature, the mixture was filtered, distilled under reduced pressure at 70 °C for 3 h, and dried under vacuum at 100 °C for 24 h to obtain the flame retardant.

[0048] Example 5: Preparation of fire-resistant composite materials:

[0049] (1) Weigh: epoxy resin: 60g, silica: 20g, flame retardant (prepared in Example 4): 10g, curing agent (diethylenetriamine): 10g, toughening agent (prepared in Example 1): 2g, accelerator (2-methylimidazole): 1g, antioxidant (antioxidant 1010): 1g;

[0050] (2) Mix epoxy resin, silica, flame retardant, toughening agent and antioxidant, stir at 90°C for 30 min, add curing agent and accelerator and stir for 20 min, cure at 100°C for 1 h, cure at 120°C for 2 h, cure at 140°C for 3 h, cool to room temperature to obtain fireproof composite material.

[0051] Example 6: Preparation of fire-resistant composite materials:

[0052] (1) Weigh: epoxy resin: 70g, silica: 25g, flame retardant (prepared in Example 4): 15g, curing agent (diethylenetriamine): 12g, toughening agent (prepared in Example 2): 4g, accelerator (2-methylimidazole): 1.5g, antioxidant (antioxidant 1076): 2g;

[0053] (2) Mix epoxy resin, silica, flame retardant, toughening agent and antioxidant, stir at 90°C for 30 min, add curing agent and accelerator and stir for 20 min, cure at 110°C for 1 h, cure at 130°C for 2 h, cure at 150°C for 3 h, cool to room temperature to obtain fireproof composite material.

[0054] Example 7 Preparation of fire-resistant composite materials:

[0055] (1) Weigh: epoxy resin: 80g, silica: 30g, flame retardant (prepared in Example 4): 18g, curing agent (aminoethylpiperazine): 15g, toughening agent (prepared in Example 3): 5g, accelerator (2-ethyl-4-methylimidazole): 2g, antioxidant (antioxidant 1076): 3g;

[0056] (2) Mix epoxy resin, silica, flame retardant, toughening agent and antioxidant, stir at 90°C for 30 min, add curing agent and accelerator and stir for 20 min, cure at 120°C for 1 h, cure at 140°C for 2 h, cure at 160°C for 3 h, cool to room temperature to obtain fireproof composite material.

[0057] Comparative Example 1

[0058] The raw material composition and process of the fire-retardant composite material are basically the same as those in Example 6, except that the toughening agent added to the component (prepared in Example 2) is replaced with an equal weight of the toughening agent prepared by the following method:

[0059] The preparation method of the toughening agent is basically the same as that in Example 2, except that the pyromellitic acid in step S1 is replaced with an equimolar amount of tricarboxylic acid.

[0060] Comparative Example 2

[0061] The raw material composition and process of the fire-retardant composite material are basically the same as those in Example 6, except that the toughening agent added to the component (prepared in Example 2) is replaced with an equal weight of the toughening agent prepared by the following method:

[0062] The preparation method of the toughening agent is basically the same as that in Example 2, except that the oleyl alcohol in step S1 is replaced with an equimolar amount of crotonol.

[0063] Comparative Example 3

[0064] The raw material composition and process of the fire-retardant composite material are basically the same as those in Example 6, except that the toughening agent added to the component (prepared in Example 2) is replaced with an equal weight of the toughening agent prepared by the following method:

[0065] S1: 500 ml toluene, 0.1 mol trimesic acid, 0.33 mol oleyl alcohol and 2 g p-toluenesulfonic acid were added sequentially to a reaction flask, stirred and mixed, heated to 90 °C, and reacted for 12 h (during which water generated in the reaction was separated by a water separator). After cooling to room temperature, the pH was adjusted to 7 with 1 M NaOH solution, and the mixture was allowed to stand and separate into layers. The mixture was washed three times with deionized water (300 ml each time), dried with 30 g anhydrous magnesium sulfate, filtered, and distilled under reduced pressure at 80 °C for 2 h to obtain the trimeryl compound.

[0066] S2: Add 1200ml of anhydrous tetrahydrofuran, 0.16mol of a trimer compound, 0.3mol of 1,4-benzenedithiol, and 5g of photoinitiator 184 to a reaction flask in sequence, stir and mix well, irradiate with 385nm ultraviolet light at room temperature for 8min, and then distill under reduced pressure at 40℃ for 2h to obtain the toughening agent.

[0067] Comparative Example 4

[0068] The raw material composition and process of the fire-retardant composite material are basically the same as those in Example 6. The difference is that the flame retardant added to the component (prepared in Example 4) is replaced with an equal weight of linear polymer (prepared in step N1 of Example 4).

[0069] Comparative Example 5

[0070] The raw material composition and process of the fire-retardant composite material are basically the same as those in Example 6, except that the flame retardant added to the components (prepared in Example 4) is replaced with an equal mass of flame retardant prepared by the following method:

[0071] The preparation method of the flame retardant is basically the same as that in Example 4, except that 4,4'-diaminodiphenyl ether in step N1 is replaced with an equimolar amount of 4,4'-diaminodiphenylmethane.

[0072] Comparative Example 6

[0073] The raw material composition and process of the fire-retardant composite material are basically the same as those in Example 6, except that the flame retardant added to the components (prepared in Example 4) is replaced with an equal mass of flame retardant prepared by the following method:

[0074] The preparation method of the flame retardant is basically the same as that in Example 4, except that the amount of 4,4'-diaminodiphenyl ether added in step N1 is replaced with 0.24 mol.

[0075] The epoxy resin used in this application is bisphenol A epoxy resin, brand name DER. TM 331, epoxy equivalent is 182g / eq; silica type is HL-200, produced by Hubei Huifu Nanomaterials Co., Ltd.

[0076] The fire-resistant composite materials prepared in Examples 5-7 and Comparative Examples 1-6 were tested for tensile strength, notched impact strength and flame retardant properties.

[0077] Tensile strength was tested according to GB / T 1040.2-2022 at a tensile speed of 50 mm / min using type 1A dumbbell-shaped specimens; notched impact strength was tested according to GB / T 1843-2008 using V-notch specimens prepared by a notch sample preparation machine; flame retardant properties were tested according to GB / T 2406.2-2009; the test results are shown in Table 1.

[0078] Table 1 Performance Test Data

[0079]

[0080] As can be seen from Examples 5, 6 and 7 in Table 1, the fire-resistant composite material prepared by the present invention has excellent mechanical strength and flame-retardant properties.

[0081] The toughening agent prepared in this application has a hyperbranched structure containing unreacted thiols, benzene rings, alkyl chains, and dynamic borate ester bonds. The three-dimensional network of the hyperbranched structure contains voids, which can absorb impact energy when the resin is subjected to impact, thus improving the resin's toughness. During curing, the thiols can undergo a cross-linking reaction with the epoxy resin, forming a homogeneous toughening phenomenon. The benzene rings and the epoxy resin matrix achieve efficient stress transfer through a π-π stacking effect. The flexible alkyl chains can deform under external force, thereby absorbing and dissipating energy, contributing to improved material toughness and impact resistance. The dynamic borate ester bonds can undergo dynamic rearrangement under external force, enabling better stress dispersion and thus improving the material's toughness.

[0082] The flame retardant prepared in this application contains elements such as P, N, and Si. Its linear polymer structure makes it easier to achieve uniform dispersion in materials and it is not prone to migration or precipitation during use, maintaining a long-term stable flame retardant effect. During combustion, phosphorus generates P-containing free radicals that inhibit combustion and promotes dehydration and carbonization of the material; nitrogen generates non-flammable gases and carbides; silicon promotes the formation of a dense, stable, and heat-insulating char layer; the rigid benzene ring structure can improve thermal stability and promote the formation of a graphitized char layer; the synergistic effect of multiple mechanisms achieves highly efficient flame retardancy in the material. The flexible ether bonds in the flame retardant can absorb impact energy and improve the impact resistance of the material. The methylsiloxane in the flame retardant can condense with the hydroxyl groups on the surface of silica, improving the dispersibility of silica and thus improving its mechanical properties.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A fire-resistant composite material, characterized in that, The ingredients include the following parts by weight: Epoxy resin: 60-80 parts, silica: 20-30 parts, flame retardant: 10-18 parts, curing agent: 10-15 parts, toughening agent: 2-5 parts, accelerator: 1-2 parts, antioxidant: 1-3 parts; The toughening agent is prepared by the following method: S1: Tristyric acid reacts with oleyl alcohol to form a triester compound; S2: 1,4-Phenylated boric acid reacts with 3-mercapto-1,2-propanediol to form a dioxoboronic heterocyclic compound; S3: Triester compounds react with dioxaboronic heterocyclic compounds to form toughening agents; The flame retardant is prepared by the following method: N1: 4,4'-Diaminodiphenyl ether reacts with phenylphosphonic dichloride to form a linear polymer; N2: Linear polymers react with γ-chloropropyltrimethoxysilane to generate flame retardants.

2. The fire-resistant composite material according to claim 1, characterized in that, In step S1, the molar ratio of pyromellitic acid and oleyl alcohol is 1:(3-3.5).

3. The fire-resistant composite material according to claim 1, characterized in that, In step S2, the molar ratio of 1,4-phenylenediboric acid and 3-mercapto-1,2-propanediol is 1:(2-2.5).

4. The fire-resistant composite material according to claim 1, characterized in that, In step S3, the molar ratio of the trimeryl compound and the dioxaboronic heterocyclic compound is (1.5-1.8):

3.

5. The fire-resistant composite material according to claim 1, characterized in that, In step N1, the molar ratio of 4,4'-diaminodiphenyl ether to phenylphosphonic dichloride is 1.2:1; in step N2, the mass ratio of the linear polymer to γ-chloropropyltrimethoxysilane is 20:

1.

6. The fire-resistant composite material according to claim 1, characterized in that, The curing agent is one of diethylenetriamine and aminoethylpiperazine.

7. The fire-resistant composite material according to claim 1, characterized in that, The accelerator is one of 2-methylimidazole and 2-ethyl-4-methylimidazole.

8. The fire-resistant composite material according to claim 1, characterized in that, The antioxidant is one of antioxidant 1010 and antioxidant 1076.

9. A method for preparing the fire-resistant composite material according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Weigh by weight: epoxy resin: 60-80 parts, silica: 20-30 parts, flame retardant: 10-18 parts, curing agent: 10-15 parts, toughening agent: 2-5 parts, accelerator: 1-2 parts, antioxidant: 1-3 parts; (2) Stir the epoxy resin, silica, flame retardant, toughening agent and antioxidant evenly, add curing agent and accelerator and stir, heat and cure to obtain fireproof composite material.

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