Biomass-based flame retardant as well as preparation and application thereof

Abstract

The invention discloses a biomass-based flame retardant as well as preparation and application thereof. The biomass-based flame retardant disclosed by the invention is prepared from biomass raw materials including vanillin, dimethyldichlorosilane, 4, 4-diaminodiphenylmethane and DOPO (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), is a novel environment-friendly halogen-free flame retardant, and has the characteristics of no toxicity, environment friendliness, good flame retardance and high compatibility with an epoxy resin matrix; when the flame-retardant epoxy resin is used for preparing a flame-retardant epoxy resin product, the obtained epoxy resin product has the characteristics of low phosphorus content, good flame retardance, high oxygen index and high mechanical strength.

Description

Technical Field

[0001] The invention relates to a flame retardant and preparation and application thereof, in particular to a biomass-based flame retardant and preparation and application thereof. Background Art

[0002] Epoxy resin is one of the most common thermosetting polymers, with excellent chemical resistance, mechanical and adhesion properties, and is widely used in many engineering fields and in our daily lives. However, the inherent flammability of epoxy resin hinders its practical application in many fields, and when epoxy resin burns, it releases a lot of heat and toxic fumes, which can cause death to humans and animals.

[0003] In practical applications, especially in fire-prone fields such as electronic appliances, it is necessary to reduce the fire risk of material parts by improving the flame retardant properties of epoxy resin. However, there are still many problems in the application of flame retardants in epoxy resin in the prior art:

[0004] First, halogen flame retardants pollute the environment;

[0005] Second, halogen-free flame retardants are not efficient enough. Compared with halogen-based flame retardants, they often require a larger amount of addition to achieve the same flame retardancy level, but this will have a great impact on other properties of epoxy resins, such as increased viscosity and decreased mechanical properties.

[0006] Third, existing halogen-free flame retardants usually have poor compatibility with epoxy resin matrices, and have a negative impact on the mechanical strength of epoxy resins after addition.

[0007] Therefore, researching and developing environmentally friendly flame retardants and their products with high flame retardant efficiency, good compatibility with epoxy resins and excellent comprehensive performance of flame retardant products is one of the key research directions of technical personnel in this field. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a biomass-based flame retardant and its preparation and application. The biomass-based flame retardant of the present invention is a new type of environmentally friendly halogen-free flame retardant, which is non-toxic and environmentally friendly, has good flame retardant properties, and has high compatibility with epoxy resin matrix; when used to prepare flame-retardant epoxy resin products, the obtained epoxy resin products have the characteristics of low phosphorus content, good flame retardant properties, high oxygen index, and high mechanical strength.

[0009] One of the technical solutions of the present invention:

[0010] A biomass-based flame retardant is provided, and its chemical structure is as follows:

[0011]

[0012] Where n>10.

[0013] The second technical solution of the present invention:

[0014] Provided is a method for preparing a biomass-based flame retardant, comprising the following steps:

[0015] S1. Take vanillin and amine reagent, dissolve them in an organic solvent, and stir for 5-15 minutes under a nitrogen atmosphere to obtain solution A;

[0016] S2. Take dimethyldichlorosilane and dissolve it in an organic solution to obtain solution B;

[0017] S3. Add solution B to solution A, stir the reaction for 3-7h, then filter to remove the amine hydrochloride salt, wash the solution with saturated sodium chloride solution and deionized water, filter, and finally distill to remove the solvent, and then dry for 10-15h to obtain a white powdery substance VDSi;

[0018] S4. Take VDSi, dissolve it in anhydrous ethanol, stir at 60-80°C for 20-40min under nitrogen atmosphere to obtain liquid C;

[0019] S5. Take 4,4-diaminodiphenylmethane and dissolve it in anhydrous ethanol to obtain solution D;

[0020] S6. Add solution D to solution C, stir and react at 60-80°C for 5-7h to obtain solution E;

[0021] S7. Take DOPO and zinc chloride, dissolve them in anhydrous ethanol to obtain liquid F;

[0022] S8. Add liquid F to liquid E, react at 60-80°C for 10-20h, cool to room temperature, dilute with an organic solvent, wash the dilution with water, distill to remove the solvent, and finally dry to obtain a light yellow powdery solid biomass-based flame retardant.

[0023] Preferably, in the aforementioned method for preparing the biomass-based flame retardant, the amine reagent in S1 is one of triethylamine, diethylamine or pyridine.

[0024] Preferably, in the aforementioned method for preparing the biomass-based flame retardant, the mass ratio of vanillin to the amine reagent in S1 is 1:1.

[0025] Preferably, in the aforementioned method for preparing the biomass-based flame retardant, the organic solvent is one of dichloromethane, ethyl acetate, tetrahydrofuran or n-hexane.

[0026] Preferably, in the aforementioned method for preparing the biomass-based flame retardant, the mass ratio of the vanillin, dimethyldichlorosilane, 4,4-diaminodiphenylmethane and DOPO is 12-18:3-9:5-11:11-17.

[0027] Preferably, in the aforementioned method for preparing the biomass-based flame retardant, the mass ratio of DOPO to zinc chloride in S7 is 142:3-5.

[0028] The third technical solution of the present invention:

[0029] Provided is an application of a biomass-based flame retardant in a flame-retardant epoxy resin.

[0030] The fourth technical solution of the present invention:

[0031] Provided is a flame retardant epoxy resin comprising the biomass-based flame retardant described in Scheme 1.

[0032] Preferably, the aforementioned flame retardant epoxy resin comprises, by weight, 100 parts of epoxy resin matrix, 2-8 parts of biomass-based flame retardant and 10-25 parts of curing agent.

[0033] Beneficial effects of the present invention:

[0034] 1. The biomass-based flame retardant of the present invention is a new type of polymer flame retardant.

[0035] 2. The biomass-based flame retardant of the present invention is prepared with biomass-based vanillin as the main raw material, and the obtained flame retardant product is a halogen-free flame retardant, which has the advantages of being non-toxic and environmentally friendly.

[0036] 3. The biomass-based flame retardant of the present invention has flame retardant components such as Si, P and N in its structure, and has good flame retardant properties. Under the same flame retardant grade, the added amount is less, and the mechanical properties and mechanical strength of the epoxy resin matrix are less affected. According to the test, the flame retardant of the present invention has good flame retardant properties when the phosphorus content is as low as 0.64%.

[0037] 4. The biomass-based flame retardant of the present invention has better compatibility with the epoxy resin matrix and a higher oxygen content, which can further improve the oxygen index of the epoxy resin. According to the test, the oxygen index of the epoxy resin added with the flame retardant of the present invention is as high as 34.3%, which is 42.9% higher than that of pure epoxy resin.

[0038] 5. The raw materials of the biomass-based flame retardant of the present invention use 4,4-diaminodiphenylmethane and dimethyldichlorosilane, so that there is a flexible chain in the chemical structure of the flame retardant. Therefore, the mechanical strength of the flame-retardant epoxy resin after adding is higher. According to the test, the UL-94 grade of the epoxy resin using the flame retardant of the present invention is V0, the bending strength is up to 30% higher than that of pure epoxy resin, and the impact strength is 171.43% higher than that of pure epoxy resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Attached Figure 1This is a comparison chart of infrared spectra of the flame retardant VDSINP of the present invention and the raw materials DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), VAN (vanillin) and the intermediate product VDSI in the preparation process.

[0040] from Figure 1 It can be seen that in the vanillin spectrum, at 3158cm -1 and 1661cm -1 The absorption peaks at 2439cm belong to the characteristic peaks of -OH and C=O stretching vibration. -1 The absorption peak belongs to the characteristic peak of the PH bond on DOPO. In the VDSI spectrum, it can be observed that the characteristic peak of -OH stretching vibration disappears, and the peak at 1100cm -1 In the VDSINP spectrum, the characteristic peaks of C=O stretching vibration and PH bond disappear. -1 and 3463cm -1 (NH stretching vibration), 1511cm -1 (PC key), 1286cm -1 (CN key), 1183cm -1 (P=O bond) and 1030cm -1 The appearance of a characteristic peak at (PO bond) indicates that a related chemical reaction has occurred.

[0041] Infrared spectroscopy can prove that relevant chemical reactions occurred between the raw materials, indirectly proving the successful synthesis of VDSINP.

[0042] Attached Figure 2 is the nuclear magnetic spectrum of the flame retardant of the present invention;

[0043] from Figure 2 It can be seen that the target product VDSiNP, the signal of the PH bond of DOPO 1 The peaks disappeared from the H-NMR curve, and some new peaks appeared in the graph. For example, the peaks at 4.53-4.62ppm are H on the benzene ring connected to the phospholipid phenanthrene structure, and the peak at 8.69ppm is the NH bond. These results indicate that the Schiff base reaction occurs between 4,40-diaminodiphenylmethane and VDSi, and then nucleophilic addition occurs between DOPO and the Schiff base structure, further illustrating the success of the synthesis reaction.

[0044] Attached Figure 3 The impact performance of the EP / VDSiNP composite material using the flame retardant of the present invention. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the embodiments, but they are not intended to limit the present invention.

[0046] Embodiments of the present invention

[0047] The reaction path of the flame retardant in the synthesis process of the embodiment of the present invention is as follows:

[0048]

[0049] Example 1

[0050] This embodiment is a biomass-based flame retardant, and its preparation method is as follows:

[0051] (1) Take 15.2 g of vanillin and 15.2 g of triethylamine reagent, dissolve them in dichloromethane solution, place them in a three-necked flask, and stir them under nitrogen atmosphere for 10 min;

[0052] (2) 6.45 g of dimethyldichlorosilane was dissolved in dichloromethane solution and then dripped into the three-necked flask of (1), and the mixture was stirred for reaction for 4 h. The generated amine hydrochloride salt was then filtered out, and the solution was washed and filtered with saturated sodium chloride solution and deionized water in sequence. Finally, the solvent was removed by rotary distillation, and the solution was dried in a drying oven for 12 h to obtain a white powdery substance (VDSi);

[0053] (3) VDSi was dissolved in anhydrous ethanol and then placed in a three-necked flask and stirred at 70 °C for 0.5 h under a nitrogen atmosphere;

[0054] (4) Take 8.2 g of 4,4-diaminodiphenylmethane (DDM), dissolve it in anhydrous ethanol, add it dropwise into the three-necked flask in (3), and react with magnetic stirring at 70°C for 6 h;

[0055] (5) 14.27 g of DOPO and 0.4 g of zinc chloride were dissolved in anhydrous ethanol and added dropwise to the three-necked flask of (3) for reaction at 70 °C for 14 h. After the reaction, the mixture was cooled to room temperature and the polymer was diluted with dichloromethane solution. The resulting mixture was washed with deionized water, and then the solvent was removed by rotary distillation. Finally, it was dried in a vacuum drying oven for 12 h to obtain a light yellow powdery solid biomass-based flame retardant VDSINP.

[0056] Example 2

[0057] This embodiment is a flame retardant epoxy resin, which is prepared by the following method:

[0058] (1) Take 30 g of the flame retardant of Example 1 and 1000 g of epoxy resin, mix them and stir them at 150° C. until they become a transparent liquid to obtain a flame retardant epoxy resin;

[0059] (2) Pour the flame-retardant modified epoxy resin of (1) and 250 g of curing agent into a mold while hot, and heat and cure at 120°C / 2h and 160°C / 2h to obtain a cured flame-retardant epoxy resin.

[0060] The cured flame-retardant epoxy resin prepared in this embodiment has an oxygen index of 28.9%, a flame retardancy grade of V1, a flexural strength of 90.42 MPa, a flexural modulus of 2377.55 MPa, and an impact strength of 15.58 kJ / m 2 .

[0061] Example 3

[0062] This embodiment is a flame retardant epoxy resin, which is prepared by the following method:

[0063] (1) Take 60 g of the flame retardant of Example 1 and 1000 g of epoxy resin, mix them and stir them at 150° C. until they become a transparent liquid to obtain a flame retardant epoxy resin;

[0064] (2) Pour the flame-retardant modified epoxy resin and 250 g of curing agent of (1) into a mold while hot, and heat and cure at 120°C / 2h and 160°C / 2h to obtain a cured flame-retardant epoxy resin.

[0065] The cured flame-retardant epoxy resin prepared in this embodiment has an oxygen index of 32.1%, a flame retardancy grade of V1, a flexural strength of 109.84 MPa, a flexural modulus of 2763.34 MPa, and an impact strength of 18.62 kJ / m 2 .

[0066] Example 4

[0067] This embodiment is a flame retardant epoxy resin, which is prepared by the following method:

[0068] (1) Take 90 g of the flame retardant of Example 1 and 1000 g of epoxy resin, mix them and stir them at 150° C. until they become a transparent liquid to obtain a flame retardant epoxy resin;

[0069] (2) Pour the flame-retardant modified epoxy resin and 250 g of curing agent of (1) into a mold while hot, and heat and cure at 120°C / 2h and 160°C / 2h to obtain a cured flame-retardant epoxy resin.

[0070] The cured flame-retardant epoxy resin prepared in this embodiment has an oxygen index of 34.3%, a flame retardancy grade of V0, a ​​flexural strength of 111.24 MPa, a flexural modulus of 3018.46 MPa, and an impact strength of 18.41 kJ / m 2 .

[0071] Example 5

[0072] This example is a comparative example of pure epoxy resin, which was prepared by the following method:

[0073] (1) Take 250g of curing agent and 1000g of epoxy resin, pour them into a mold while hot, and heat to cure at 120℃ / 2h and 160℃ / 2h to obtain cured pure epoxy resin.

[0074] The cured pure epoxy resin prepared in this embodiment has an oxygen index of 24%, no flame retardancy, a flexural strength of 85.6 MPa, a flexural modulus of 1756 MPa, and an impact strength of 6.86 kJ / m 2 .

[0075] The flame retardant performance test results of the epoxy resin materials of Examples 2-5 are shown in Table 1 below:

[0076] Table 1

[0077] name UL-94 LOI(%) EP - 24 EP / VDSINP3 V1 28.9 EP / VDSINP6 V0 32.1 EP / VDSINP9 V0 34.3

[0078] The EP item is the pure epoxy resin sample of Example 5, and the EP / VDSINP3, EP / VDSINP6 and EP / VDSINP9 items correspond to the epoxy resin composite materials prepared in Examples 2-4, respectively.

[0079] Example 6

[0080] This embodiment is a biomass-based flame retardant, and its preparation method is as follows:

[0081] (1) Take 12 g of vanillin and 12 g of diethylamine reagent, dissolve them in ethyl acetate solution and place them in a three-necked flask, and stir them under nitrogen atmosphere for 5 min;

[0082] (2) Take 3 g of dimethyldichlorosilane, dissolve it in ethyl acetate solution and then drip it into the three-necked flask of (1), stir and react for 3 hours, then filter to remove the generated amine hydrochloride salt, wash and filter the solution with saturated sodium chloride solution and deionized water in turn, finally remove the solvent by rotary distillation, and place it in a drying oven to dry for 10 hours to obtain a white powdery substance (VDSi);

[0083] (3) VDSi was dissolved in anhydrous ethanol and then placed in a three-necked flask and stirred at 60 °C for 20 min under a nitrogen atmosphere;

[0084] (4) Take 5 g of 4,4-diaminodiphenylmethane (DDM), dissolve it in anhydrous ethanol, drop it into the three-necked flask in (3), and react with magnetic stirring at 60°C for 5 h;

[0085] (5) 11 g of DOPO and 0.3 g of zinc chloride were dissolved in anhydrous ethanol, and added dropwise to the three-necked flask of (3) for reaction at 60 °C for 10 h. After the reaction, the mixture was cooled to room temperature, and the polymer was diluted with ethyl acetate solution. The resulting mixture was washed with deionized water, and then the solvent was removed by rotary distillation. Finally, it was dried in a vacuum drying oven for 12 h to obtain a light yellow powdery solid biomass-based flame retardant VDSINP.

[0086] Example 7

[0087] This embodiment is a biomass-based flame retardant, and its preparation method is as follows:

[0088] (1) Take 18 g of vanillin and 18 g of pyridine reagent, dissolve them in n-hexane solution and place them in a three-necked flask, and stir them under nitrogen atmosphere for 15 min;

[0089] (2) 9 g of dimethyldichlorosilane was dissolved in n-hexane solution and then dripped into the three-necked flask of (1), stirred for reaction for 7 h, then filtered to remove the generated amine hydrochloride salt, the solution was washed and filtered with saturated sodium chloride solution and deionized water in turn, and finally the solvent was removed by rotary distillation, and the solution was placed in a drying oven for 10 h to obtain a white powdery substance (VDSi);

[0090] (3) VDSi was dissolved in anhydrous ethanol and then placed in a three-necked flask and stirred at 80 °C for 40 min under a nitrogen atmosphere;

[0091] (4) Take 11 g of 4,4-diaminodiphenylmethane (DDM), dissolve it in anhydrous ethanol, add it dropwise into the three-necked flask in (3), and react with magnetic stirring at 80°C for 7 h;

[0092] (5) 17 g of DOPO and 0.5 g of zinc chloride were dissolved in anhydrous ethanol, and added dropwise to the three-necked flask in (3) for reaction at 80 °C for 20 h. After the reaction, the mixture was cooled to room temperature, and the polymer was diluted with n-hexane solution. The resulting mixture was washed with deionized water, and then the solvent was removed by rotary distillation. Finally, it was dried in a vacuum drying oven for 12 h to obtain a light yellow powdery solid biomass-based flame retardant VDSINP.

[0093] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A biomass-based flame retardant, characterized in that: Its chemical structure is as follows: Where n>10.

2. A method for preparing a biomass-based flame retardant according to claim 1, characterized in that: The steps include: S1. Take vanillin and amine reagent, dissolve them in an organic solvent, and stir for 5-15 minutes under a nitrogen atmosphere to obtain solution A; S2. Take dimethyldichlorosilane and dissolve it in an organic solution to obtain solution B; S3. Add solution B to solution A, stir the reaction for 3-7h, then filter to remove the amine hydrochloride salt, wash the solution with saturated sodium chloride solution and deionized water, filter, and finally distill to remove the solvent, and then dry for 10-15h to obtain a white powdery substance VDSi; S4. Take VDSi, dissolve it in anhydrous ethanol, stir at 60-80°C for 20-40min under nitrogen atmosphere to obtain liquid C; S5. Take 4,4-diaminodiphenylmethane and dissolve it in anhydrous ethanol to obtain solution D; S6. Add solution D to solution C, stir and react at 60-80°C for 5-7h to obtain solution E; S7. Take DOPO and zinc chloride, dissolve them in anhydrous ethanol to obtain liquid F; S8. Add liquid F to liquid E, react at 60-80°C for 10-20h, cool to room temperature, dilute with an organic solvent, wash the dilution with water, distill to remove the solvent, and finally dry to obtain a light yellow powdery solid biomass-based flame retardant.

3. The method for preparing a biomass-based flame retardant according to claim 2, characterized in that: The amine reagent in S1 is one of triethylamine, diethylamine or pyridine.

4. The method for preparing a biomass-based flame retardant according to claim 2, characterized in that: The mass ratio of vanillin and amine reagent in S1 is 1:

1.

5. The method for preparing a biomass-based flame retardant according to claim 2, characterized in that: The organic solvent is one of dichloromethane, ethyl acetate, tetrahydrofuran or n-hexane.

6. The method for preparing a biomass-based flame retardant according to claim 2, characterized in that: The mass ratio of the vanillin, dimethyldichlorosilane, 4,4-diaminodiphenylmethane and DOPO is 12-18:3-9:5-11:11-17.

7. The method for preparing a biomass-based flame retardant according to claim 2, characterized in that: The mass ratio of DOPO and zinc chloride in S7 is 142:3-5.

8. Use of the biomass-based flame retardant according to claim 1 in flame-retardant epoxy resin.

9. A flame retardant epoxy resin, characterized in that: Contains the biomass-based flame retardant according to claim 1.

10. The flame retardant epoxy resin according to claim 9, characterized in that: Calculated by weight, it includes 100 parts of epoxy resin matrix, 2-8 parts of biomass-based flame retardant and 10-25 parts of curing agent.

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