A bio-based flame retardant DOPO-Res and its preparation method and application

Abstract

The present invention provides a bio-based flame retardant DOPO-Res and a preparation method and application thereof. The preparation method of the bio-based flame retardant DOPO-Res comprises stirring DOPO and an organic solvent at a first preset temperature to obtain a first mixed solution; stirring the first mixture, resveratrol and triethylamine at a second preset temperature to obtain a second mixed solution; slowly dripping carbon tetrachloride into the second mixed solution under stirring and at a third preset temperature, reacting for a first preset time, and then continuing to react for a second preset time under stirring and at a fourth preset temperature until the reaction is complete to obtain a reaction solution, and the reaction solution is post-treated to obtain the bio-based flame retardant DOPO-Res. The structure of the bio-based flame retardant DOPO-Res provided by the present invention contains P elements and a relatively large number of benzene ring structures, so that during the combustion process of the polymer material, the polymer quickly promotes the carbonization of the polymer, isolates oxygen, captures free radicals, and has a gas phase and condensed phase flame retardant effect on the material, thereby improving the flame retardancy of the epoxy resin.

Description

Technical Field

[0001] The invention belongs to the technical field of flame retardancy, and specifically relates to a bio-based flame retardant DOPO-Res and a preparation method and application thereof. Background Art

[0002] Epoxy resin (EP), as a common thermosetting polymer, is widely used in electronic packaging, biochemical engineering, building materials, aerospace and other fields due to its excellent corrosion resistance, dielectric properties, adhesion and easy processing. However, EP composite materials without flame retardants are limited by shortcomings such as poor thermal stability and easy combustion, and release smoke and harmful substances when burning, which limits its further application. In order to improve the flame retardant properties of EP, adding traditional halogen flame retardants can no longer meet people's pursuit of green and clean environmental protection concepts. Therefore, the research and development of halogen-free flame retardants to improve the flame retardant properties of EP has become a hot trend.

[0003] In recent years, due to the many negative impacts of traditional halogen flame retardants on human health and the ecological environment, they have been gradually eliminated and faded out of the historical stage. As a non-halogen environmentally friendly flame retardant, bio-based flame retardants are renewable and green and non-toxic, which conforms to the concept of sustainable development. The patent document of Chinese patent CN115594714A publicly published "a green preparation method and application of bio-based flame retardants with phytic acid as the base plate". A biomass flame retardant containing flame retardant elements such as phosphorus and nitrogen was prepared by a relatively complex process using phytic acid as the raw material. Chinese patent CN110746646A uses vanillin as the main raw material, adds dichlorodimethylsilane dropwise under nitrogen, further reacts in dichloromethane to obtain intermediate (I), and then reacts with aminophenol / primary aminophenol to obtain intermediate (II), then adds azobisisobutyronitrile DOPO, and then adds intermediate (II) to finally obtain a biomass-based flame retardant. Summary of the invention

[0004] The object of the present invention is to provide a new bio-based flame retardant DOPO-Res, which has the advantages of simple preparation process and mild reaction conditions, and the bio-based flame retardant DOPO-Res is applied to flame-retardant epoxy resin with the advantages of small addition amount and good flame retardant effect.

[0005] In order to achieve the above object, the present invention provides a bio-based flame retardant DOPO-Res, the chemical structure of the bio-based flame retardant DOPO-Res is:

[0006]

[0007] The present invention also provides a method for preparing a bio-based flame retardant DOPO-Res, and the preparation route thereof comprises:

[0008]

[0009] The preparation method comprises the following steps:

[0010] Step (1), at a first preset temperature, stirring DOPO and an organic solvent to obtain a first mixed solution, wherein the organic solvent is dichloromethane or tetrahydrofuran;

[0011] Step (2), at a second preset temperature, stirring the first mixed solution, resveratrol and triethylamine to obtain a second mixed solution;

[0012] Step (3), slowly dripping carbon tetrachloride into the second mixed liquid under stirring and at a third preset temperature, reacting for a first preset time, and then continuing to react for a second preset time under stirring and at a fourth preset temperature until the reaction is complete to obtain a reaction liquid, and the reaction liquid is post-treated to obtain the bio-based flame retardant DOPO-Res.

[0013] In a specific embodiment, in step (1), the first preset temperature is 0-10°C; in step (2), the second preset temperature is 0-10°C.

[0014] In a specific embodiment, the third preset temperature in step (3) is 0-8°C, the first preset time is 1h-3h, the fourth preset temperature is room temperature, and the second preset time is 16h-24h. In a specific embodiment, in step (1), the mass volume ratio of the DOPO to the organic solvent is: (10-12) g: (40-60) ml.

[0015] In a specific embodiment, in step (2), the mass ratio of resveratrol to triethylamine is (1-2): (3.9-4.9), and the mass ratio of resveratrol to DOPO is (3-4): (11.2-12.2).

[0016] In a specific embodiment, in step (3), the molar ratio of carbon tetrachloride to DOPO is 1:(1.1-1.5).

[0017] In a specific embodiment, the post-treatment includes extraction, washing, rotary distillation and drying.

[0018] In a specific embodiment, the extractant used in the extraction step is 0.1-1 mol / L hydrochloric acid; the rotary distillation conditions include: the rotary distillation temperature is 50-60° C., and the rotary distillation time is 0.5-2 h.

[0019] The present invention also provides an application of a bio-based flame retardant DOPO-Res, wherein the bio-based flame retardant DOPO-Res is used to prepare a flame-retardant epoxy resin; wherein the bio-based flame retardant DOPO-Res is the bio-based flame retardant DOPO-Res described above; or, the bio-based flame retardant DOPO-Res is prepared by the preparation method described above.

[0020] In a specific embodiment, the preparation method of the flame retardant epoxy resin includes: heating the epoxy resin to 120-150°C under stirring, then adding the bio-based flame retardant DOPO-Res, stirring evenly, and adjusting the temperature of the mixture system to 80-100°C; then adding the curing agent 4,4'-diaminodiphenylmethane and continuing to stir until there is no block solid in the new mixture system; pouring the mixture consisting of the epoxy resin, the bio-based flame retardant DOPO-Res and the 4,4'-diaminodiphenylmethane into a preheated mold, and drying it twice to obtain a flame retardant epoxy resin, wherein, based on the mass of the epoxy resin as 100%, the added amount of the bio-based flame retardant DOPO-Res is 1wt%~8wt% of the mass of the epoxy resin, and the added amount of the 4,4'-diaminodiphenylmethane is 23.8wt%~25.8wt% of the mass of the epoxy resin.

[0021] In a specific embodiment, the conditions for the first drying include: a drying temperature of 100-120° C., and a drying time of 2-4 hours; the conditions for the second drying include: a drying temperature of 120-150° C., and a drying time of 2-4 hours.

[0022] The beneficial effects of the present invention include at least:

[0023] 1. The bio-based flame retardant DOPO-Res provided by the present invention, referred to as DOPR, contains the P element and a relatively large number of benzene ring structures in its structure, so that during the combustion process of the polymer material, the polymer can be rapidly promoted to carbonize, oxygen can be isolated, and free radicals can be captured, which has a gas phase and condensed phase flame retardant effect on the material, thereby improving the flame retardancy of the flame retardant epoxy resin.

[0024] 2. The bio-based flame retardant DOPO-Res provided by the present invention first allows DOPO to undergo a substitution reaction with the carbon tetrachloride at 0-8°C, and then allows the product of the substitution reaction to undergo an etherification reaction with resveratrol at room temperature to generate DOPR. The synthesis process is simple and the synthesis conditions are mild, which overcomes the technical difficulties of the existing poor flame retardant efficiency and complex preparation process.

[0025] 3. The resveratrol, the raw material of the DOPR bio-based flame retardant of the present invention, is renewable and has high thermal stability. It combines with the flame retardant intermediate of the DOPO flame retardant to form a compound, which will bring excellent flame retardant properties to the flame retardant epoxy resin, and has the characteristics of low smoke and halogen-free. Compared with traditional flame retardants, it is more environmentally friendly and in line with the concept of sustainable development.

[0026] Fourth, the bio-based flame retardant DOPO-Res and epoxy resin are mixed to prepare flame-retardant epoxy resin, which has the advantages of small addition amount and good flame retardant effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a Fourier transform infrared image of the bio-based flame retardant DOPO-Res prepared in Example 1 of the present invention;

[0028] Figure 2 This is a hydrogen nuclear magnetic resonance spectrum of the bio-based flame retardant DOPO-Res prepared in Example 1 of the present invention;

[0029] Figure 3 This is the nuclear magnetic resonance phosphorus spectrum of the bio-based flame retardant DOPO-Res prepared in Example 1 of the present invention;

[0030] Figure 4 This is a comparison chart of heat release rates of different contents of the bio-based flame retardant DOPO-Res prepared in Example 1 of the present invention in epoxy resin;

[0031] Figure 5 This is a comparison chart of the total heat release of different contents of the bio-based flame retardant DOPO-Res prepared in Example 1 of the present invention in epoxy resin;

[0032] Figure 6 This is a comparison chart of the total smoke generation of different contents of the bio-based flame retardant DOPO-Res prepared in Example 1 of the present invention in epoxy resin;

[0033] Figure 7 This is a comparison chart of the residual carbon rates of different contents of the bio-based flame retardant DOPO-Res prepared in Example 1 of the present invention in epoxy resin. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0035] The present invention provides a bio-based flame retardant DOPO-Res, and the chemical structural formula of the bio-based flame retardant DOPO-Res is:

[0036]

[0037] In the present invention, the bio-based flame retardant DOPO-Res is referred to as DOPR.

[0038] In the present invention, the structure of the DOPR contains P element and a relatively large number of benzene ring structures, so that during the combustion process of the polymer material, the polymer is rapidly promoted to carbonize, oxygen is isolated, and free radicals are captured, which has a gas phase and condensed phase flame retardant effect on the material, thereby improving the flame retardancy of the flame retardant epoxy resin.

[0039] The present invention also provides a method for preparing a bio-based flame retardant DOPO-Res, which comprises the following steps:

[0040] Step 1: At a first preset temperature, DOPO and an organic solvent are stirred evenly to obtain a first mixed solution, wherein the organic solvent is dichloromethane or tetrahydrofuran.

[0041] Preferably, the mass volume ratio of the DOPO to the organic solvent is: (10-12) g: (40-60) ml.

[0042] Preferably, the first preset temperature is 0-10°C.

[0043] The step is specifically as follows: dissolving DOPO in a container containing dichloromethane (DCM) or tetrahydrofuran, placing the container in a magnetic stirrer equipped with a water bath for stirring, and stirring evenly to obtain a first mixture, wherein the temperature of the water bath is controlled at 0-10° C., and the stirring time is controlled at 0.1-0.5 h.

[0044] Step 2: at a second preset temperature, stirring the first mixed solution, resveratrol and triethylamine to obtain a second mixed solution.

[0045] Preferably, the second preset temperature is 0-10°C.

[0046] Preferably, the mass ratio of resveratrol to triethylamine is (1-2):(3.9-4.9), and the mass ratio of resveratrol to DOPO is (3-4):(11.2-12.2).

[0047] This step is specifically as follows: under stirring, resveratrol Res and triethylamine TEA are added to the container containing the first mixed solution (DOPO solution) in sequence, and stirred evenly to obtain a second mixed solution, wherein during the mixing process, the stirring temperature is controlled at 0-10° C., and the stirring time is controlled at 5 min to 30 min.

[0048] In the present invention, the triethylamine TEA is slowly added with a dropper.

[0049] It should be noted that this step is used to mix the DOPO solution, resveratrol and triethylamine evenly.

[0050] Step three, slowly dripping carbon tetrachloride into the second mixed liquid under stirring and at a third preset temperature, reacting for a first preset time, and then continuing to react for a second preset time under stirring and at a fourth preset temperature until the reaction is complete to obtain a reaction liquid, and the reaction liquid is post-treated to obtain the bio-based flame retardant DOPO-Res.

[0051] In the present invention, the step three includes two steps of reaction, wherein the first step is a substitution reaction between DOPO and carbon tetrachloride, in which the hydrogen atom in the PH bond in DOPO is replaced by a Cl atom to become P-Cl; the second step is an etherification reaction between the reaction product of DOPO and carbon tetrachloride and resveratrol Res, in which the P-Cl bond in DOPO reacts with the -OH bond of resveratrol to generate hydrochloric acid, and in which triethylamine is used as an acidifying agent to promote the forward reaction.

[0052] It should be noted that within the first preset time, the substitution reaction and the etherification reaction are carried out simultaneously, and the reaction is continued at the fourth preset temperature for the second preset time in order to ensure a more complete etherification reaction.

[0053] Wherein, the reaction equation of the substitution reaction is:

[0054]

[0055] The reaction equation of the etherification reaction is:

[0056]

[0057] Preferably, in this step, the third preset temperature is 0-8° C., the first preset time is 1 h-3 h, the fourth preset temperature is room temperature, and the second preset time is 16 h-24 h.

[0058] Preferably, the molar ratio of carbon tetrachloride to DOPO is 1:(1.1-1.5), and more preferably, the molar ratio of carbon tetrachloride to DOPO is 1:1.2.

[0059] In the present invention, the post-treatment includes extraction, washing, rotary distillation and drying.

[0060] Preferably, the extractant used in the extraction step is 0.1-1 mol / L hydrochloric acid.

[0061] Preferably, the washing step comprises washing with hydrochloric acid and deionized water sequentially for 3 to 5 times.

[0062] It can be understood as washing with hydrochloric acid 3 to 5 times first, and then washing with deionized water 3 to 5 times.

[0063] Preferably, the rotary distillation conditions include: a rotary distillation temperature of 50 to 60° C., and a rotary distillation time of 0.5 to 2 h.

[0064] Preferably, the drying conditions include: a drying temperature of 90 to 110° C. and a drying time of 12 to 16 hours.

[0065] The present invention also provides an application of a bio-based flame retardant DOPO-Res, wherein the bio-based flame retardant DOPO-Res is used to prepare a flame-retardant epoxy resin; wherein the bio-based flame retardant DOPO-Res is the bio-based flame retardant DOPO-Res described above; or, the bio-based flame retardant DOPO-Res is prepared by the preparation method described above.

[0066] In the present invention, the preparation method of the flame retardant epoxy resin comprises the following steps: heating the epoxy resin to 120-150° C. under stirring, then adding the bio-based flame retardant DOPO-Res, stirring evenly, and adjusting the temperature of the mixture system to 80-100° C.; then adding the curing agent 4,4'-diaminodiphenylmethane and continuing to stir until there is no blocky solid in the new mixture system; pouring the mixture consisting of the epoxy resin, the bio-based flame retardant DOPO-Res and the 4,4'-diaminodiphenylmethane into a preheated mold, and drying it twice to obtain the flame retardant epoxy resin.

[0067] Preferably, based on 100% of the mass of the epoxy resin, the amount of the bio-based flame retardant DOPO-Res added is 1wt% to 8wt% of the mass of the epoxy resin, and the amount of 4,4'-diaminodiphenylmethane added is 23.8wt% to 25.8wt% of the mass of the epoxy resin.

[0068] Preferably, the conditions for the first drying include: a drying temperature of 100 to 120° C. and a drying time of 2 to 4 hours; and the conditions for the second drying include: a drying temperature of 120 to 150° C. and a drying time of 2 to 4 hours.

[0069] Example 1

[0070] Preparation of bio-based flame retardant DOPR

[0071] First, DOPO (11.2 g, 0.051 mol) was dissolved in a flask containing 60 ml of dichloromethane (DCM), and the solution was stirred in a magnetic stirrer equipped with an ice-water bath. After stirring evenly, resveratrol Res (3.0 g, 0.013 mol) and triethylamine TEA (6.27 g, 0.062 mol) were added to the DOPO solution in sequence. TEA was slowly added with a dropper, and the water bath temperature was controlled at 0-10°C and stirred for 10 min. Then CCl4 (9.55 g, 0 .062mol), the temperature was controlled at 0-8°C, stirred for 2h, and then reacted at room temperature of 24°C for 24h to obtain a reaction product; the reaction product was placed in a separatory funnel, washed with 0.1mol / L HCl and deionized water for multiple times, and during separation, an organic liquid was separated from the lower end, and a waste liquid was poured out from the upper end; the organic solution was placed in a rotary evaporator and concentrated at 80°C for 10min to remove excess organic solvent, and finally a viscous liquid was formed, and a drying oven was heated at 100°C for 12h, and DOPR was dried to obtain a yield of 82.4%

[0072] Figure 1 This is the Fourier transform infrared image of the bio-based flame retardant DOPR prepared in Example 1, where 754 cm -1 The P-Ph absorption peak of DOPO is 3064cm -1 The peaks at 1476 cm-1 are attributed to the stretching vibration absorption peak of =CH on the benzene ring. -1 The peak at 1194 cm is attributed to the stretching vibration of the benzene ring, indicating that DOPO derivatives exist in the reaction product. -1 , 1276cm -1 The absorption peak is the characteristic peak of P=O bond stretching, 1116cm -1 The absorption peak of 3200 is the stretching vibration peak of POC. -1 ~3400cm -1 The absorption peaks correspond to the hydroxyl group (-OH) of Res, and these peaks of the newly synthesized compound almost disappeared, indicating that it can be preliminarily confirmed that the target product has been synthesized.

[0073] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the bio-based flame retardant DOPR prepared in Example 1. From the 1H NMR spectrum, it can be seen that the symmetrical quartet in the range of 6.7-6.9ppm belongs to the peak of the hydrogen atoms on the carbon-carbon double bonds between the benzene rings. Except for the peak at the chemical shift of 6.63ppm, which belongs to the peak corresponding to the hydrogen atom numbered 1 on the benzene ring, the peaks corresponding to the hydrogen atoms on the other benzene rings are all between 7.0 and 8.1ppm.

[0074] Figure 3This is the nuclear magnetic resonance phosphorus spectrum of the bio-based flame retardant DOPR prepared in Example 1. In the 1P NMR spectrum, the single peak at 6.74 ppm and the symmetrical double peak at 12.34 ppm are both attributed to the peaks corresponding to the three phosphorus atoms on DOPR. Figures 1 to 3 , demonstrating the successful synthesis of compound DOPR.

[0075] Example 2

[0076] Preparation of flame retardant epoxy resin

[0077] First, pour 100 grams of epoxy resin EP into a beaker and place it firmly in a magnetic stirrer with an oil bath. Heat it to 140°C, and quickly stir the EP liquid with a rotor. Dissolve 1.26 grams of DOPR in the EP liquid, and continue stirring for 5 minutes to fully mix. Adjust the temperature of the mixture system to 90°C, and then pour in 24.8 grams of curing agent 4,4'-diaminodiphenylmethane (DDM) and stir for 15 minutes. When DDM and EP are mixed until no blocky solids appear, pour them into a preheated polytetrafluoroethylene mold, place them in a blast drying oven at 110°C and 130°C for two hours, respectively, and obtain a flame-retardant epoxy resin after natural cooling.

[0078] In this embodiment, the added amount of DOPR is 1 wt % of the mass of the epoxy resin EP.

[0079] Example 3

[0080] Example 3 is substantially the same as Example 2, the only difference being that the amount of DOPR added is 3.86 g. In this case, the amount of DOPR added is 3 wt % of the mass of the epoxy resin EP.

[0081] Example 4

[0082] Example 4 is substantially the same as Example 2, except that the added amount of DOPR is 6.57 g. In this case, the added amount of DOPR is 5 wt % of the mass of the epoxy resin EP.

[0083] Comparative Example

[0084] The comparative example is substantially the same as Example 2, except that the mass of the added DOPR is 0 g.

[0085] The flame retardant properties of the flame retardant epoxy resins prepared in Examples 2 to 4 and the comparative example were tested to evaluate the combustion behavior and flame retardant properties of the polymer materials in a real fire scene. The test results are detailed in Table 1.

[0086] It should be noted that when the flame retardant properties of the prepared flame retardant epoxy resin are tested, the limiting oxygen index (LOI) method used refers to the ASTM D2863 test standard; the vertical burning test (UL-94) adopts the GB / T2408 standard; and the cone calorimeter test (CONE) adopts the ISO5660 standard.

[0087] Table 1 Key parameters of combustion performance of flame-retardant epoxy resins prepared in Examples 2 to 4 and Comparative Examples

[0088]

[0089] The data in Table 1 are converted into a graphic file. Figures 4 to 7 .

[0090] It can be seen from Table 1 that different DOPR addition amounts can improve the flame retardant effect of epoxy resin, as follows:

[0091] (1) Flame retardant epoxy resin containing 0% DOPR:

[0092] Flame retardant properties of the material: ignition time is 66s; limiting oxygen index is only 22.44%; UL-94 fire rating is not passed (NR); peak heat release rate (pHRR) is 435.13kW / m 2 ; Total heat release (THR) is 57.83MJ / m 2 ; Total smoke production (TSP) is 44.49m 2 ; The residual carbon rate is 7.02%.

[0093] (2) Flame retardant epoxy resin containing 1% DOPR:

[0094] Flame retardant properties of the material: the limiting oxygen index is only 26.30%; the UL-94 fire rating is V-1

[0095] (3) Flame retardant epoxy resin containing 3% DOPR:

[0096] Flame retardant properties of the material: ignition time is 64s; limiting oxygen index is only 27.55%; UL-94 fire rating reaches V-0; peak heat release rate (pHRR) is 388.43kW / m 2 ; Total heat release (THR) is 43.37MJ / m 2 ; Total smoke production (TSP) is 39.55m 2 ; The residual carbon rate is 15.10%.

[0097] (4) Flame retardant epoxy resin containing 5% DOPR:

[0098] Flame retardant properties of the material: ignition time is 60s; limiting oxygen index is only 28.19%; UL-94 fire rating reaches V-0; peak heat release rate (pHRR) is 367.04kW / m 2 ; Total heat release (THR) is 38.67MJ / m 2 ; Total smoke production (TSP) is 40.21m 2 ; The residual carbon rate is 16.69%.

[0099] In summary, through comparison of the obtained data, it can be seen that compared with pure epoxy resin, the flame retardant properties of the flame retardant epoxy resin gradually increase with the increase of the added amount. When 5wt% DOPR flame retardant epoxy resin is added, the prepared flame retardant epoxy resin reaches the higher level V-0 of UL-94.

[0100] When the bio-flame retardant DOPR is used in the preparation of flame-retardant epoxy resin, the amount of DOPR added can be increased as needed to further improve product performance and meet market needs.

[0101] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A bio-based flame retardant DOPO-Res, characterized in that: The chemical structural formula of the bio-based flame retardant DOPO-Res is:

2. A method for preparing a bio-based flame retardant DOPO-Res, characterized in that: The preparation method comprises the following steps: Step (1), at a first preset temperature, DOPO and an organic solvent are stirred to obtain a first mixed solution, wherein the organic solvent is dichloromethane or tetrahydrofuran, wherein the structural formula of DOPO is Step (2), at a second preset temperature, stirring the first mixed solution, resveratrol and triethylamine to obtain a second mixed solution; Step (3), slowly dripping carbon tetrachloride into the second mixed liquid under stirring and at a third preset temperature, reacting for a first preset time, and then continuing to react for a second preset time under stirring and at a fourth preset temperature until the reaction is complete to obtain a reaction liquid, and the reaction liquid is post-treated to obtain the bio-based flame retardant DOPO-Res, wherein the chemical structure of the bio-based flame retardant DOPO-Res is:

3. The method for preparing the bio-based flame retardant DOPO-Res according to claim 2, characterized in that: In step (1), the first preset temperature is 0 to 10°C; in step (2), the second preset temperature is 0 to 10°C.

4. The method for preparing the bio-based flame retardant DOPO-Res according to claim 3, characterized in that: In step (3), the third preset temperature is 0-8°C, the first preset time is 1h-3h, the fourth preset temperature is room temperature, and the second preset time is 16h-24h.

5. The method for preparing the bio-based flame retardant DOPO-Res according to any one of claims 2 to 4, characterized in that: In step (1), the mass volume ratio of the DOPO to the organic solvent is: (10-12) g: (40-60) ml; in step (2), the mass ratio of the resveratrol to triethylamine is (1-2): (3.9-4.9), and the mass ratio of the resveratrol to DOPO is (3-4): (11.2-12.2).

6. The method for preparing the bio-based flame retardant DOPO-Res according to any one of claims 2 to 4, characterized in that: In step (3), the molar ratio of carbon tetrachloride to DOPO is 1:(1.1-1.5).

7. The method for preparing the bio-based flame retardant DOPO-Res according to claim 2, characterized in that: The post-treatment includes extraction, washing, rotary distillation and drying.

8. The method for preparing the bio-based flame retardant DOPO-Res according to claim 7, characterized in that: The extractant used in the extraction step is 0.1-1 mol / L hydrochloric acid; the conditions of the rotary distillation include: the rotary distillation temperature is 50-60° C., and the rotary distillation time is 0.5-2 h.

9. An application of a bio-based flame retardant DOPO-Res, characterized in that: The bio-based flame retardant DOPO-Res is used to prepare flame-retardant epoxy resin; wherein the bio-based flame retardant DOPO-Res is the bio-based flame retardant DOPO-Res according to claim 1; or, the bio-based flame retardant DOPO-Res is prepared by the preparation method according to any one of claims 2 to 8.

10. The use according to claim 9, characterized in that: The preparation method of the flame retardant epoxy resin comprises: heating the epoxy resin to 120-150° C. under stirring, then adding the bio-based flame retardant DOPO-Res, stirring evenly, and adjusting the temperature of the mixture system to 80-100° C.; then adding a curing agent 4,4'-diaminodiphenylmethane and continuing to stir until there is no blocky solid in the new mixture system; pouring a mixture consisting of the epoxy resin, the bio-based flame retardant DOPO-Res and the 4,4'-diaminodiphenylmethane into a preheated mold, and drying twice to obtain the flame retardant epoxy resin, wherein, based on the mass of the epoxy resin being 100%, the added amount of the bio-based flame retardant DOPO-Res is 1wt%-8wt% of the mass of the epoxy resin, and the added amount of the 4,4'-diaminodiphenylmethane is 23.8wt%-25.8wt% of the mass of the epoxy resin.

Images