Efficient organic phosphorus DI-DOPO flame retardant and preparation method thereof

Abstract

The invention relates to the technical field of flame retardants, and discloses an efficient organophosphorus DI-DOPO flame retardant and a preparation method thereof.The preparation method comprises the following steps that S1, an olefinic bond-containing intermediate is prepared, specifically, allyl glycidyl ether, diethanol amine, polyethylene glycol monomethyl ether acrylate and glycerol react to obtain the olefinic bond-containing intermediate; s2, preparing a phosphorus-containing monomer: reacting the olefinic bond-containing intermediate, DOPO (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), a sulfonic acid functionalized mesoporous molecular sieve catalyst as a catalyst, vanillin glycidyl ether as a modifier and a gamma-valerolactone solvent as a modifier to obtain a grafted and modified refined phosphorus-containing monomer; and S3, preparation of a DI-DOPO flame retardant: carrying out a reaction on a phosphorus-containing monomer, a compound of gamma-methacryloxypropyltrimethoxysilane and cardanol acrylate, a mixed solvent of ethyl acetate and ethanol, and an initiator 2, 2 '-azobis (2-methylpropionamide) dihydrochloride, so as to obtain the final efficient organic phosphorus DI-DOPO flame retardant, wherein the phosphorus-containing monomer, the compound of gamma-methacryloxypropyltrimethoxysilane and cardanol acrylate, the mixed solvent of ethyl acetate and ethanol, and the initiator 2, 2'-azobis (2-methylpropionamide) dihydrochloride are subjected to a reaction.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of flame retardants, in particular to a high-efficiency organic phosphorus DI-DOPO flame retardant and a preparation method thereof. BACKGROUND

[0002] With the increasing requirements of society for fire safety and environmental protection, the application of flame retardants in various materials is becoming increasingly critical. Organic phosphorus flame retardants occupy an important position in the flame retardant market due to their low toxicity, low smoke and good flame retardant performance. Among them, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and its derivatives have been widely studied and concerned due to their special molecular structure and chemical properties.

[0003] The biphenyl and heterophenanthrene ring structure contained in the DOPO molecule endows it with high thermal stability and chemical stability, and the active p-h bond enables it to react with various unsaturated groups to generate derivatives with different properties, providing the possibility for the development of diversified flame retardants. However, there are still many problems in the current DOPO-based flame retardants. First, the compatibility with the polymer matrix is poor, which leads to the aggregation of the material and the decrease of the mechanical properties; second, the heat resistance is insufficient, which is difficult to meet the requirements of high-temperature scenes; third, the environmental friendliness of the preparation process is poor, and a large amount of toxic solvents such as toluene and tetrahydrofuran are used, resulting in a large amount of acidic wastewater. Therefore, it is of great practical significance and market demand to develop a DOPO-based flame retardant with excellent comprehensive performance, good compatibility with materials, simple and efficient preparation method and environmental friendliness. SUMMARY

[0004] (I) Technical problems to be solved

[0005] In view of the deficiencies of the prior art, the application provides a high-efficiency organic phosphorus DI-DOPO flame retardant and a preparation method thereof.

[0006] (II) Technical scheme

[0007] To achieve the above-mentioned purpose, the application provides the following technical scheme: a preparation method of a high-efficiency organic phosphorus DI-DOPO flame retardant, comprising the following steps:

[0008] S1, preparation of an intermediate containing an alkene bond: mixing allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol, and then reacting, purifying and refining to obtain an intermediate containing an alkene bond;

[0009] S2, preparation of a phosphorus-containing monomer: mixing the obtained intermediate containing an alkene bond, DOPO and a catalyst sulfonic acid functionalized mesoporous molecular sieve catalyst, a modifier vanillin glycidyl ether and a gamma-valerolactone solvent, and then reacting, filtering, neutralizing, separating and drying to obtain a refined phosphorus-containing monomer grafted and modified;

[0010] S3, Preparation of DI-DOPO flame retardant: The phosphorus-containing monomer obtained above, the compound of γ-methacryloyloxypropyltrimethoxysilane and cardanol acrylate with a mass ratio of 1:1, and the mixed solvent of ethyl acetate and ethanol with a volume ratio of 3:1 were mixed, and then the initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride was added after the system was stable. After reaction, the product was filtered, washed and dried to obtain the final high-efficiency organic phosphorus DI-DOPO flame retardant.

[0011] Further, in step S1, the molar ratio of allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol is 1:1.2-1.5:0.1-0.3:10-12.

[0012] Further, in step S2, the molar ratio of the intermediate containing olefinic bond, DOPO, sulfonic acid functionalized mesoporous molecular sieve catalyst, vanillin glycidyl ether and γ-valerolactone solvent is 1:1.1-1.5:0.04-0.06:0.1-0.15:10-12.

[0013] Further, in step S2, a 0.45 μm ceramic filter membrane is used for filtration to separate the sulfonic acid functionalized mesoporous molecular sieve catalyst.

[0014] Further, in step S3, the molar ratio of the phosphorus-containing monomer, 2,2'-azobis(2-methylpropionamide) dihydrochloride, the compound of γ-methacryloyloxypropyltrimethoxysilane and cardanol acrylate, and the mixed solvent of ethyl acetate and ethanol is 1:0.04-0.06:0.12-0.16:12-16.

[0015] Further, in step S3, the initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride is slowly added in the form of an ethanol solution with a mass concentration of 10%, and the dropping time is 20-30 min.

[0016] Further, in steps S1-S3, nitrogen is introduced during the reaction process, and the nitrogen flow rate is 80-100 mL / min.

[0017] Further, in step S2, the sulfonic acid functionalized mesoporous molecular sieve catalyst separated by filtration is washed with γ-valerolactone for 2 times and then dried at 100-120℃ for 3-5 h for repeated use.

[0018] Further, in step S3, the mother liquor and washing liquid collected by filtration are separated and recovered by rectification, and about 85% of ethyl acetate and ethanol can be recovered, which is purified and used for reaction again.

[0019] (III) Beneficial technical effects

[0020] The epoxy group in the allyl glycidyl ether reacts with the amino group of diethanolamine to form an intermediate containing a hydroxyl group and an amino group, and at the same time, the double bond of the polyethylene glycol monomethyl ether acrylate reacts with the allyl group of the allyl glycidyl ether to realize graft modification and introduce a hydrophilic polyether segment. The double bond in the intermediate reacts with DOPO to introduce phosphorus elements into the molecular structure, and the epoxy group of vanillin glycidyl ether reacts with the hydroxyl group of the intermediate to realize grafting and introduce an aromatic ring structure. DI-DOPO flame retardant: under the initiation of 2,2'-azobis(2-methylpropionamide) dihydrochloride, the double bond of the phosphorus-containing monomer reacts with the double bond of the modifier to form a cross-linked structure.

[0021] The present application takes the synergistic effect of phosphorus-silicon-natural flame-retardant groups, DOPO provides a phosphorus-based flame-retardant core, siloxane enhances the stability of the carbon layer, and the bio-based component such as cardanol promotes carbon formation, forming a high-efficiency flame-retardant system. The flame-retardant performance is excellent, the heat resistance is outstanding, the use demand in high-temperature environment is met, green and environmentally friendly reagents are used, the development trend of green chemical industry is met, and economic benefits and environmental benefits are combined. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0023] The components of the high-efficiency organic phosphorus DI-DOPO flame retardant formula of the present application are all commercially available unless otherwise specified.

[0024] Embodiment 1

[0025] A preparation method of a high-efficiency organic phosphorus DI-DOPO flame retardant, comprising the following steps:

[0026] S1, preparation of an intermediate containing an olefinic bond: mixing allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol, and then reacting, purifying and refining to obtain an intermediate containing an olefinic bond;

[0027] S2, preparation of a phosphorus-containing monomer: mixing the intermediate containing an olefinic bond obtained above, DOPO, a catalyst sulfonic acid functionalized mesoporous molecular sieve catalyst, a modifier vanillin glycidyl ether and a gamma-valerolactone solvent, and then reacting, suction filtering, neutralizing, separating and drying to obtain a refined phosphorus-containing monomer grafted and modified;

[0028] S3, Preparation of DI-DOPO flame retardant: the phosphorus-containing monomer obtained above, the compound of γ-methacryloxypropyltrimethoxysilane and cardanol acrylate with a mass ratio of 1:1, and the mixed solvent of ethyl acetate and ethanol with a volume ratio of 3:1 were mixed, and then the initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride was added after the system was stabilized. After reaction, filtration, washing and drying, the final high-efficiency organic phosphorus DI-DOPO flame retardant was obtained.

[0029] In step S1, the molar ratio of allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol was 1:1.2:0.1:10.

[0030] In step S2, the molar ratio of the intermediate containing olefinic bond, DOPO, sulfonic acid functionalized mesoporous molecular sieve catalyst, vanillin glycidyl ether and γ-valerolactone solvent was 1:1.1:0.04:0.1:10.

[0031] In step S2, 0.45 μm ceramic filter membrane was used for filtration to separate the sulfonic acid functionalized mesoporous molecular sieve catalyst.

[0032] In step S3, the molar ratio of the phosphorus-containing monomer, 2,2'-azobis(2-methylpropionamide) dihydrochloride, the compound of γ-methacryloxypropyltrimethoxysilane and cardanol acrylate, and the mixed solvent of ethyl acetate and ethanol was 1:0.04:0.12:12.

[0033] In step S3, the initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride was slowly added in the form of a 10% ethanol solution, and the dropping time was 20 min.

[0034] In steps S1-S3, nitrogen was introduced during the reaction process, and the nitrogen flow rate was 80 mL / min.

[0035] The preparation method of the intermediate containing olefinic bond comprises the following steps:

[0036] A1, in a reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol were sequentially added, nitrogen was introduced, the reaction system was heated to 80℃, and the stirring speed was controlled at 150 rpm, and the reaction was carried out for 1 h;

[0037] A2, after the reaction was completed, the reaction liquid was cooled to room temperature, deionized water was added to the reaction liquid, stirred for 10 min, then transferred to a separatory funnel and left to separate for 30 min, and after separation, the upper organic phase was taken and washed with deionized water for 3 times;

[0038] A3, take the washed organic phase, add anhydrous sodium sulfate for drying, the amount of anhydrous sodium sulfate is 1 / 5 of the volume of the organic phase, seal and stand for drying for 2h, filter out the drying agent to obtain the crude product containing the olefinic intermediate;

[0039] A4, place the crude product containing the olefinic intermediate in a rotary evaporator, evaporate the residual small amount of water at 65℃ under reduced pressure (vacuum degree 0.09MPa) to obtain the refined olefinic intermediate.

[0040] The preparation method of the phosphorus-containing monomer comprises the following steps:

[0041] B1, in a dry three-necked flask, sequentially add the olefinic intermediate, DOPO, the sulfonic acid functionalized mesoporous molecular sieve catalyst, the modifier vanillin glycidyl ether and the γ-valerolactone solvent, install the stirrer, thermometer and reflux condenser, introduce nitrogen protection, start stirring, set the stirring speed to 160rpm, slowly warm up to 110℃, and react at this temperature for 2h;

[0042] B2, after the reaction is completed, cool the reaction liquid to 60℃, separate out the sulfonic acid functionalized mesoporous molecular sieve catalyst by vacuum filtration, slowly add saturated sodium bicarbonate solution to the filtrate for neutralization, stir while adding until the pH value of the solution reaches 7.0, and stand for 10min;

[0043] B3, transfer the neutralized mixed liquid to a separatory funnel, stand for 15min to separate into layers, separate out the lower organic phase, wash the washed organic phase with deionized water for 3 times, add anhydrous calcium sulfate to the washed organic phase for drying, the amount of anhydrous calcium sulfate is 1 / 6 of the volume of the organic phase, seal and stand for drying for 1.5h;

[0044] B4, filter out the drying agent to obtain the crude product containing the phosphorus-containing monomer, transfer the solution to a rotary evaporator, evaporate the γ-valerolactone solvent at 75℃ under a vacuum degree of 0.08MPa, dry the remaining product in a vacuum drying oven at 50℃ for 2h to obtain the refined graft-modified phosphorus-containing monomer;

[0045] The preparation method of the DI-DOPO flame retardant comprises the following steps:

[0046] C1, prepare the following raw materials: phosphorus-containing monomer, initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride, modifier γ-methacryloyloxypropyltrimethoxysilane and cashew phenol acrylate compound (mass ratio 1:1) and mixed solvent of ethyl acetate and ethanol (volume ratio 3:1);

[0047] C2, in a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, the phosphorus-containing monomer, the modifier, the mixed solvent were sequentially added, nitrogen was introduced for protection, the stirring was started, the stirring speed was set to 110 rpm, the temperature was raised to 62℃, after the system temperature was stable, the initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride was slowly added into the reaction system, the reaction was continued for 3h;

[0048] C3, after the reaction was completed, the reaction liquid was cooled to room temperature, then slowly added into deionized water, while stirring, after the addition was completed, it was placed for 20 min, the precipitate was collected by suction filtration, then transferred to a beaker, deionized water was added, after stirring and washing, it was suction filtered, the washing process was repeated for 3 times;

[0049] C4, the washed precipitate was placed in a vacuum drying oven, dried to constant weight under the conditions of 55℃ and vacuum degree 0.06 MPa, the grafted modified DI-DOPO flame retardant was obtained.

[0050] Example 2

[0051] A preparation method of a high-efficiency organic phosphorus DI-DOPO flame retardant, comprising the following steps:

[0052] S1, preparation of an intermediate containing an olefin bond: allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol were mixed, reacted, purified, refined, and an intermediate containing an olefin bond was obtained;

[0053] S2, preparation of a phosphorus-containing monomer: the intermediate containing an olefin bond obtained above, DOPO, a sulfonic acid functionalized mesoporous molecular sieve catalyst, a modifier vanillyl glycidyl ether and a γ-valerolactone solvent were mixed, reacted, suction filtered, neutralized, separated and dried, and a refined phosphorus-containing monomer was obtained;

[0054] S3, preparation of a DI-DOPO flame retardant: the phosphorus-containing monomer obtained above, a compound of γ-methacryloyloxypropyl trimethoxysilane and cardanol acrylate with a mass ratio of 1:1, and a mixed solvent of ethyl acetate and ethanol with a volume ratio of 3:1 were mixed, after the system was stable, an initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride was added, after the reaction, suction filtration, washing and drying were carried out, and finally a high-efficiency organic phosphorus DI-DOPO flame retardant was obtained.

[0055] In step S1, the molar ratio of allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol was 1:1.3:0.2:11.

[0056] In step S2, the molar ratio of the intermediate containing an olefin bond, DOPO, a sulfonic acid functionalized mesoporous molecular sieve catalyst, vanillyl glycidyl ether and a γ-valerolactone solvent was 1:1.3:0.05:0.12:11.

[0057] In step S2, the filter membrane with a pore size of 0.45 μm is used for filtration to separate the sulfonic acid functionalized mesoporous molecular sieve catalyst.

[0058] In step S3, the molar ratio of the phosphorus-containing monomer, 2,2'-azobis(2-methylpropionamide) dihydrochloride, γ-methacryloxypropyltrimethoxysilane and cashew phenol acrylate complex, and the mixed solvent of ethyl acetate and ethanol is 1:0.05:0.14:14.

[0059] In step S3, the initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride is slowly added in the form of an ethanol solution with a mass concentration of 10%, and the dropping time is 25 min.

[0060] In steps S1-S3, nitrogen is introduced for protection during the reaction, and the nitrogen flow rate is 90 mL / min.

[0061] The preparation method of the intermediate containing an olefinic bond comprises the following steps:

[0062] A1. In a reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol are sequentially added, nitrogen is introduced for protection, the reaction system is warmed to 85°C, the stirring speed is controlled at 180 rpm, and the reaction is carried out for 1.5 h;

[0063] A2. After the reaction is completed, the reaction liquid is cooled to room temperature, deionized water is added to the reaction liquid, stirred for 15 min, and then transferred to a separatory funnel for standing and layering for 40 min. After separation, the upper organic phase is taken and washed with deionized water for 3 times.

[0064] A3. The washed organic phase is taken, anhydrous sodium sulfate is added for drying, the amount of anhydrous sodium sulfate is 1 / 5 of the volume of the organic phase, and the mixture is sealed and dried for 2.5 h. The drying agent is removed by filtration to obtain a crude product of the intermediate containing an olefinic bond.

[0065] A4. The crude product of the intermediate containing an olefinic bond is placed in a rotary evaporator, and the residual small amount of water is evaporated under the conditions of 65°C and reduced pressure (vacuum degree 0.09 MPa) to obtain a refined intermediate containing an olefinic bond.

[0066] The preparation method of the phosphorus-containing monomer comprises the following steps:

[0067] B1. In a dry three-necked flask, the intermediate containing an olefinic bond, DOPO, the catalyst sulfonic acid functionalized mesoporous molecular sieve catalyst, the modifier vanillin glycidyl ether and the γ-valerolactone solvent are sequentially added, a stirrer, a thermometer and a reflux condenser are installed, nitrogen is introduced for protection, the stirring is started, the stirring speed is set to 180 rpm, and the temperature is slowly increased to 110°C. The reaction is carried out at this temperature for 3 h.

[0068] B2, after the reaction, the reaction liquid is cooled to 60 DEG C, by vacuum filtration to separate out the sulfonic acid functionalized mesoporous molecular sieve catalyst, to the filtrate slowly add saturated sodium bicarbonate solution for neutralization, side add side stirring, until the solution pH value reaches 7.0, 15 min;

[0069] B3, the neutralized mixture is transferred to a separatory funnel, and is allowed to stand for 20 min to separate into layers, and the lower organic phase is separated and washed with deionized water three times, and the washed organic phase is dried with anhydrous calcium sulfate, the amount of anhydrous calcium sulfate being 1 / 6 of the volume of the organic phase, and the mixture is sealed and allowed to stand for drying for 2 h;

[0070] B4, the drying agent is filtered off to obtain a crude phosphorus-containing monomer solution, and the solution is transferred to a rotary evaporator, and the gamma-valerolactone solvent is evaporated at 75 DEG C and a vacuum degree of 0.082 MPa, and the remaining product is dried in a vacuum drying oven at 55 DEG C for 3 h to obtain a refined phosphorus-containing monomer grafted with a modifier.

[0071] The preparation method of the DI-DOPO flame retardant includes the following steps:

[0072] C1, the following raw materials are prepared: a phosphorus-containing monomer, an initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride, a modifier gamma-methacryloyloxypropyl trimethoxysilane, a compound of cashew phenol acrylate (mass ratio 1:1), and a mixed solvent of ethyl acetate and ethanol (volume ratio 3:1);

[0073] C2, in a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, the phosphorus-containing monomer, the modifier and the mixed solvent are sequentially added, nitrogen is introduced for protection, the stirring speed is set to 120 rpm, the temperature is raised to 63 DEG C, and after the system temperature is stabilized, the initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride is slowly added to the reaction system, and the reaction is continued for 4 h;

[0074] C3, after the reaction, the reaction liquid is cooled to room temperature, and then slowly added to deionized water while stirring, and after the addition is completed, the mixture is allowed to stand for 25 min, and the precipitate is collected by suction filtration, and then transferred to a beaker, deionized water is added, and the mixture is washed by stirring and suction filtration, and the washing process is repeated three times;

[0075] C4, the washed precipitate is placed in a vacuum drying oven and dried at 60 DEG C and a vacuum degree of 0.08 MPa until the weight is constant to obtain the grafted DI-DOPO flame retardant.

[0076] Example 3

[0077] A preparation method of a high-efficiency organic phosphorus DI-DOPO flame retardant includes the following steps:

[0078] S1, preparation of an olefin-containing intermediate: allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol are mixed, reacted, purified, refined to obtain an olefin-containing intermediate;

[0079] S2, preparation of a phosphorus-containing monomer: the above-obtained olefin-containing intermediate, DOPO and a catalyst sulfonic acid functionalized mesoporous molecular sieve catalyst, a modifier vanillin glycidyl ether and a γ-valerolactone solvent are mixed, reacted, filtered, neutralized, separated and dried to obtain a refined phosphorus-containing monomer modified by grafting;

[0080] S3, preparation of a DI-DOPO flame retardant: the above-obtained phosphorus-containing monomer, a modifier compound of γ-methacryloxypropyl trimethoxysilane and cardanol acrylate in a mass ratio of 1:1, and a mixed solvent of ethyl acetate and ethanol in a volume ratio of 3:1 are mixed, and then an initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride is added after the system is stabilized, and the mixture is filtered, washed and dried after reaction to obtain a final high-efficiency organic phosphorus DI-DOPO flame retardant.

[0081] In step S1, the molar ratio of allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol is 1:1.5:0.3:12.

[0082] In step S2, the molar ratio of the olefin-containing intermediate, DOPO, the sulfonic acid functionalized mesoporous molecular sieve catalyst, vanillin glycidyl ether and γ-valerolactone solvent is 1:1.5:0.06:0.15:12.

[0083] In step S2, a 0.45 μm ceramic filter is used for filtration to separate the sulfonic acid functionalized mesoporous molecular sieve catalyst.

[0084] In step S3, the molar ratio of the phosphorus-containing monomer, 2,2'-azobis(2-methylpropionamide) dihydrochloride, the compound of γ-methacryloxypropyl trimethoxysilane and cardanol acrylate, and the mixed solvent of ethyl acetate and ethanol is 1:0.06:0.16:16.

[0085] In step S3, the initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride is slowly added in the form of a 10% ethanol solution, and the dropping time is 30 min.

[0086] In steps S1-S3, nitrogen is introduced during the reaction process, and the nitrogen flow rate is 100 mL / min.

[0087] The preparation method of the olefin-containing intermediate comprises the following steps:

[0088] A1, in a reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol were sequentially added, nitrogen was introduced for protection, the reaction system was heated to 90°C, the stirring speed was controlled at 200 rpm, and the reaction was carried out for 2 h;

[0089] A2, after the reaction was completed, the reaction liquid was cooled to room temperature, deionized water was added to the reaction liquid, stirred for 15 min, then transferred to a separatory funnel and separated for 60 min, after separation, the upper organic phase was taken and washed with deionized water for 3 times;

[0090] A3, the washed organic phase was taken, anhydrous sodium sulfate was added for drying, the amount of anhydrous sodium sulfate was 1 / 5 of the volume of the organic phase, sealed and dried for 3 h, the drying agent was removed by filtration, and a crude product containing an olefinic bond intermediate was obtained;

[0091] A4, the crude product containing the olefinic bond intermediate was placed in a rotary evaporator, and the residual small amount of water was evaporated under the conditions of 65°C and reduced pressure (vacuum degree 0.09 MPa) to obtain a refined olefinic bond intermediate.

[0092] The preparation method of the phosphorus-containing monomer comprises the following steps:

[0093] B1, in a dry three-necked flask, the olefinic bond intermediate, DOPO, the catalyst sulfonic acid functionalized mesoporous molecular sieve catalyst, the modifier vanillin glycidyl ether and the γ-valerolactone solvent were sequentially added, a stirrer, a thermometer and a reflux condenser were installed, nitrogen was introduced for protection, the stirring was started, the stirring speed was set to 200 rpm, and the temperature was slowly increased to 115°C, and the reaction was carried out for 4 h at this temperature;

[0094] B2, after the reaction was completed, the reaction liquid was cooled to 60°C, the sulfonic acid functionalized mesoporous molecular sieve catalyst was separated by vacuum filtration, and saturated sodium bicarbonate solution was slowly added to the filtrate for neutralization, and the stirring was continued until the pH value of the solution reached 7.0, and the solution was left to stand for 15 min;

[0095] B3, the neutralized mixture was transferred to a separatory funnel, left to stand for 25 min, and the lower organic phase was separated, washed with deionized water for 3 times, and the dried with anhydrous calcium sulfate, the amount of anhydrous calcium sulfate was 1 / 6 of the volume of the organic phase, and the mixture was sealed and dried for 2.5 h;

[0096] B4, the drying agent was removed by filtration to obtain a crude solution of the phosphorus-containing monomer, the solution was transferred to a rotary evaporator, the γ-valerolactone solvent was evaporated under the conditions of 75°C and vacuum degree 0.085 MPa, and the remaining product was dried in a vacuum drying oven at 60°C for 4 h to obtain a refined graft-modified phosphorus-containing monomer;

[0097] The preparation method of the DI-DOPO flame retardant comprises the following steps:

[0098] C1, prepare the following raw materials: phosphorus-containing monomer, initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride, modifier γ-methacryloyloxypropyl trimethoxysilane and cashew phenol acrylate compound (mass ratio 1:1) and mixed solvent of solvent ethyl acetate and ethanol (volume ratio 3:1);

[0099] C2, in a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, sequentially add the phosphorus-containing monomer, the modifier, the mixed solvent, and protect with nitrogen, start stirring, set the stirring speed to 130 rpm, heat to 65℃, after the system temperature is stable, slowly add the initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride to the reaction system, continue to react for 6h;

[0100] C3, after the reaction is completed, cool the reaction liquid to room temperature, then slowly add it to deionized water while stirring, after the addition is completed, stand for 30 min, collect the precipitate by suction filtration, transfer the precipitate to a beaker, add deionized water, stir and filter, repeat the washing process for 3 times;

[0101] C4, place the washed precipitate in a vacuum drying oven, dry to constant weight at 65℃ under the condition of vacuum degree 0.09MPa, to obtain the grafted modified DI-DOPO flame retardant.

[0102] Comparative Example 1

[0103] In step S1, no polyethylene glycol monomethyl ether acrylate is added, and the rest of the process is the same as Example 1.

[0104] In step S2, no vanillin glycidyl ether is added, and the rest of the process is the same as Example 1.

[0105] In step S3, no γ-methacryloyloxypropyl trimethoxysilane and cashew phenol acrylate compound is added, and the rest of the process is the same as Example 1.

[0106] Performance test:

[0107] 1. Limiting oxygen index (LOI) test: test according to GB / T2406.2-2009 "Plastics - Determination of the burning behavior in an oxygen index apparatus - Part 2: Test method in room temperature". Add the flame retardants prepared in Examples 1-3 and Comparative Examples 1-3 to epoxy resin at an addition amount of 15%, respectively, to prepare standard samples (length 120mm, width 10mm, thickness 4mm), and measure the limiting oxygen index in an oxygen index tester.

[0108] 2. UL-94 Vertical Burning Grade Test: According to the standard of UL94-2013 "Standard Test for Flammability of Plastic Materials for Parts in Devices and Appliances", the epoxy resin added with 15% flame retardant was made into a standard sample with a length of 127 mm, a width of 12.7 mm, and a thickness of 3.2 mm, and tested in a vertical burning tester. The burning time, dripping condition, etc. of the sample were observed to determine its burning grade.

[0109] 3. Thermogravimetric Analysis (TGA) Test: According to the relevant provisions of GB / T27761-2011 "Determination of Ash Content in Solid Biomass Fuels by Thermogravimetric Analysis", the thermogravimetric analysis method was used. The sample was heated from room temperature to 800℃ at a rate of 10℃ / min under nitrogen atmosphere, and the 5% weight loss temperature and the maximum weight loss rate temperature were recorded.

[0110] Table 1 Limiting Oxygen Index Test Results

[0111] Group Limiting Oxygen Index Example 1 36％ Example 2 38％ Example 3 37％ Comparative Example 1 30％ Comparative Example 2 32％ Comparative Example 3 29％

[0112] Table 2 UL-94 Vertical Burning Grade Test Results

[0113] Group UL-94 Vertical Burning Rating Example 1 V-0 rating Example 2 V-0 rating Example 3 V-0 rating Comparative Example 1 V-2 rating Comparative Example 2 V-1 rating Comparative Example 3 V-2 rating

[0114] Table 3 Thermogravimetric Analysis (TGA) Test Results

[0115] Group 5% Weight Loss Temperature (°C) Maximum Weight Loss Rate Temperature (°C) Example 1 360 420 Example 2 375 435 Example 3 370 430 Comparative Example 1 320 380 Comparative Example 2 330 390 Comparative Example 3 310 370

[0116] From the above test results, it can be seen that the high-efficiency organic phosphorus DI-DOPO flame retardant prepared in Examples 1-3 is superior to the three comparative examples in various performance indicators, highlighting the advantages of adding a modifier in the present application.

[0117] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing high efficiency organophosphorus DI-DOPO flame retardant, characterized in that, The method comprises the following steps: S1, preparation of an intermediate containing an olefinic bond: mixing allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol, reacting, purifying, refining, and obtaining an intermediate containing an olefinic bond; S2, preparation of a phosphorus-containing monomer: mixing the intermediate containing an olefinic bond obtained above, DOPO, a sulfonic acid functionalized mesoporous molecular sieve catalyst, a modifier vanillin glycidyl ether and a gamma-valerolactone solvent, reacting, suction filtering, neutralizing, separating, and drying, and obtaining a refined phosphorus-containing monomer modified by grafting; S3, preparation of a DI-DOPO flame retardant: mixing the phosphorus-containing monomer obtained above, a compound of gamma-methacryloxypropyltrimethoxysilane and cardanol acrylate with a mass ratio of 1:1, and a mixed solvent of ethyl acetate and ethanol with a volume ratio of 3:1, slowly adding an initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride after the system is stable, suction filtering, washing and drying after reacting, and obtaining a final high-efficiency organic phosphorus DI-DOPO flame retardant.

2. A process for the preparation of high efficiency organophosphorus DI-DOPO flame retardant according to claim 1, characterized by, In step S1, the molar ratio of allyl glycidyl ether, diethanolamine, polyethylene glycol monomethyl ether acrylate and glycerol is 1:1.2-1.5:0.1-0.3:10-12.

3. A process for the preparation of high efficiency organophosphorus DI-DOPO flame retardant according to claim 1, characterized by, In step S2, the molar ratio of the intermediate containing an olefinic bond, DOPO, a sulfonic acid functionalized mesoporous molecular sieve catalyst, vanillin glycidyl ether and a gamma-valerolactone solvent is 1:1.1-1.5:0.04-0.06:0.1-0.15:10-12.

4. The method according to claim 1, wherein the method is characterized by, In step S2, a 0.45 μm ceramic filter membrane is used for suction filtering to separate the sulfonic acid functionalized mesoporous molecular sieve catalyst.

5. The method according to claim 1, wherein the method is characterized by, In step S3, the molar ratio of the phosphorus-containing monomer, 2,2'-azobis(2-methylpropionamide) dihydrochloride, the compound of gamma-methacryloxypropyltrimethoxysilane and cardanol acrylate, and the mixed solvent of ethyl acetate and ethanol is 1:0.04-0.06:0.12-0.16:12-16.

6. The method of claim 1, wherein the method is characterized by, In step S3, the initiator 2,2'-azobis(2-methylpropionamide) dihydrochloride is slowly added in the form of an ethanol solution with a mass concentration of 10%, and the dropping time is 20-30 min.

7. The method according to claim 1, wherein the method is characterized by, In steps S1-S3, nitrogen is introduced for protection during the reaction process, and the nitrogen flow rate is 80-100 mL / min.

8. The method of claim 1, wherein the method is characterized by, In step S2, the sulfonic acid functionalized mesoporous molecular sieve catalyst separated by suction filtering is washed twice with gamma-valerolactone and then dried at 100-120°C for 3-5 h for repeated use.

9. The method of claim 1, wherein the method is characterized by, In step S3, the mother liquor and washing liquid collected by suction filtering are separated and recovered by rectification, and about 85% of ethyl acetate and ethanol can be recovered and used for reaction again after purification.