Unsaturated polyester resin-based halogen-free flame-retardant material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high polymer materials, and relates to an unsaturated polyester resin-based halogen-free flame-retardant material as well as a preparation method and application thereof. The unsaturated polyester resin-based halogen-free flame-retardant material is prepared from the following components in parts by weight: 30 to 50 parts of intrinsic flame-retardant unsaturated polyester resin prepolymer, 5 to 20 parts of unsaturated hydroxy fatty acid, 10 to 40 parts of flame retardant aluminum hydroxide, 5 to 20 parts of black scale nanosheet modified by non-covalent interaction of ionic liquid, 1 to 2 parts of initiator, 1 to 3 parts of antioxidant and 5 to 10 parts of polyester plasticizer. Monomers containing flame-retardant elements are polymerized into unsaturated polyester resin in situ, and meanwhile, the modified flame retardant containing unsaturated double bonds, unsaturated hydroxy fatty acid and other components are added, so that the flame-retardant property and mechanical property of the material can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to an unsaturated polyester resin-based halogen-free flame retardant material and a preparation method and application thereof. Background Art

[0002] With the continuous strengthening of national environmental protection and safety awareness, craft products made of halogen-free flame retardant materials have become the first choice in many industries. Although traditional halogen-containing flame retardant materials have excellent flame retardant properties, they will produce a large amount of toxic gases and smoke during the combustion process, causing serious harm to the environment and human health, so they are gradually eliminated by the market. In contrast, halogen-free flame retardant materials not only have good flame retardant effects, but also can significantly reduce the release of toxic gases and smoke during fires, better protect the lives of personnel, and facilitate escape and rescue work. Therefore, the development of halogen-free flame retardant materials has become an important trend in industrial development. Unsaturated polyester resin (UPR for short) is a linear polymer compound formed by the condensation of diols and unsaturated dicarboxylic acids (anhydrides), which has the characteristics of strong designability, low cost, and excellent molding performance. However, traditional UPR materials are extremely flammable, and their combustion will also release a large amount of toxic pyrolysis gases and smoke, endangering life and health, and hindering escape and rescue work. Therefore, flame retardant modification of UPR materials is an inevitable measure to reduce their flammability and broaden their application breadth.

[0003] The compound use of flame retardants is currently a common idea for preparing flame-retardant UPR materials. By compounding different types of flame retardants, a synergistic effect can be achieved and the flame retardant effect can be improved. When designing the formula, it is crucial to choose the right flame retardant, not only to ensure that the mechanical properties of the material are not significantly affected, but also to meet the requirements of the new version of low-smoke halogen-free flame retardant materials such as low smoke and low toxicity. In addition, compared with the blending modification system, the in-situ polymerization of monomers or flame retardants containing flame retardant elements into unsaturated polyester resins through copolymerization to improve the flame retardancy of the material is a very promising preparation method. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an unsaturated polyester resin-based halogen-free flame retardant material and a preparation method and application thereof.

[0005] One object of the present invention is achieved by the following technical solutions:

[0006] A method for preparing an intrinsic flame-retardant unsaturated polyester resin prepolymer comprises the following steps:

[0007] (1) reacting barium hydroxide and tetrakis(hydroxymethyl)phosphonium sulfate at 40-80° C. for 1-10 hours, and centrifuging to obtain a supernatant; dripping a hydrogen peroxide solution into the supernatant, and reacting at 10-50° C. for 1-10 hours after the dripping is complete, and extracting and decompressing to obtain a first-stage product; adding an alkaline compound and a phase transfer catalyst to the first-stage product, and then adding 4-chloro-α-methylstyrene to react to obtain a copolymerizable monomer containing a C=C bond;

[0008] (2) 1,2-propylene glycol, trimethylolpropane and maleic anhydride are reacted at 150-200° C. under an inert atmosphere for 1-10 hours, and then the temperature is maintained to continue the reduced pressure reaction for 0.5-5 hours. After the temperature is reduced to 90-120° C., the copolymerizable monomer containing a C=C bond of step (1) is added, and the mixture is stirred evenly to obtain an intrinsic flame retardant unsaturated polyester resin prepolymer.

[0009] In step (1) of the preparation method, preferably, barium hydroxide and tetrakis(hydroxymethyl)phosphonium sulfate react in the presence of water, and the molar ratio of tetrakis(hydroxymethyl)phosphonium sulfate to barium hydroxide is preferably 0.8-1.2:1; the concentration of the hydrogen peroxide solution is preferably 10-50wt%; the molar ratio of tetrakis(hydroxymethyl)phosphonium sulfate to hydrogen peroxide is preferably 1:1-3; the phase transfer catalyst is preferably one or more of tetrabutylammonium bromide (TBAB), benzyltriethylammonium chloride (TEBAC), hexadecyltrimethylammonium bromide (HTMAB), etc.; the alkaline compound can be listed as one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, triethylamine, etc.; the molar ratio of 4-chloro-α-methylstyrene to the first step product is 3-4:1.

[0010] In step (1) of the preparation method, preferably, a basic compound and a phase transfer catalyst are added to the product of the first step at 20 to 40° C., and then the reaction system is placed in an ice bath, 4-chloro-α-methylstyrene is added and stirred for reaction for 0.5 to 5 hours, and then the temperature is raised to 30 to 60° C. and reacted for 2 to 20 hours.

[0011] In step (1) of the preparation method, preferably, the molar ratio of 1,2-propylene glycol, trimethylolpropane and maleic anhydride is preferably 1:0.3-0.7:0.3-0.7; the molar ratio of the copolymerizable monomer containing a C=C bond to maleic anhydride is preferably 1-5:1.

[0012] The inert atmosphere herein may be exemplified by nitrogen, argon and the like.

[0013] The second object of the present invention is achieved by the following technical solutions:

[0014] An intrinsic flame-retardant unsaturated polyester resin prepolymer is prepared by the above preparation method.

[0015] The third object of the present invention is achieved by the following technical solutions:

[0016] An unsaturated polyester resin-based halogen-free flame retardant material comprises the following components in parts by weight: 30-50 parts of intrinsic flame retardant unsaturated polyester resin prepolymer, 5-20 parts of unsaturated hydroxy fatty acid, 10-40 parts of flame retardant aluminum hydroxide, 5-20 parts of synergistic flame retardant, 1-2 parts of initiator, 1-3 parts of antioxidant and 5-10 parts of polyester plasticizer.

[0017] Preferably, the selected unsaturated hydroxy fatty acid is 3-hydroxy-4-hexenoic acid.

[0018] Preferably, the synergistic flame retardant is black scale nanosheets (IL-BP) modified by non-covalent action of ionic liquid.

[0019] Further preferably, the method for preparing the black-scale nanosheets modified by the non-covalent action of the ionic liquid comprises the following steps:

[0020] The black scale is prepared into black scale nanosheets by dry ball milling and / or liquid phase ultrasonic method; the black scale nanosheets are added into an organic solvent, and then an ionic liquid is added, and ultrasonic treatment is performed for 1 to 10 hours, and then centrifuged for the first time to remove the detached black scale crystals, and the supernatant is centrifuged for the second time to collect the precipitate, and IL-BP is obtained after drying.

[0021] In the above-mentioned preparation method of IL-BP, preferably, the organic solvent is one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, etc. Preferably, the mass ratio of black scale nanosheets to ionic liquid is preferably 1:0.5-3. The speed and centrifugation time of the second centrifugation are greater than those of the first centrifugation. Preferably, the speed of the first centrifugation is 1000-5000rpm / min, and the centrifugation time is 1-6min; the speed of the second centrifugation is 9000-15000rpm / min, and the centrifugation time is 8-15min.

[0022] In the above-mentioned preparation method of IL-BP, preferably, the ionic liquid is one or more of 1,3-dimethyl imidazole methyl sulfate (CAS: 97345-90-9), 1-vinyl-3-methyl imidazole methyl sulfate (CAS: 26591-72-0), 1,3-dimethyl imidazole nitrate (CAS: 941584-21-0), 1-vinyl-3-methyl imidazole nitrate (CAS: 1072788-90-9), 1,3-dimethyl imidazole methanesulfonate (CAS: 521304-36-9), 1-ethyl-3-methyl imidazole methanesulfonic acid (CAS: 145022-45-3), etc. More preferably, it is an ionic liquid with a double bond, such as one or more of 1-vinyl-3-methyl imidazole methyl sulfate, 1-vinyl-3-methyl imidazole nitrate, etc.

[0023] Preferably, the initiator includes one or more of a peroxide compound initiator and an azo initiator. More preferably, the initiator is a peroxide compound initiator, which can be exemplified by one or more of cyclohexanone peroxide, methyl ethyl ketone peroxide, benzoyl peroxide, lauroyl peroxide, tert-butyl perbenzoate, tert-butyl pervalerate, and the like.

[0024] Preferably, the antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant. Further preferably, the selected antioxidant is a composite antioxidant formed by a hindered phenol antioxidant and a phosphite antioxidant in a mass ratio of 1:0.5-2.

[0025] Preferably, the polyester plasticizer is one or more of diethylene glycol dibenzoate and phthalate plasticizers.

[0026] The fourth object of the present invention is achieved by the following technical solutions:

[0027] A method for preparing an unsaturated polyester resin-based halogen-free flame retardant material comprises the following steps:

[0028] The intrinsic flame retardant unsaturated polyester resin prepolymer, unsaturated hydroxy fatty acid, flame retardant aluminum hydroxide and antioxidant are mixed in a mixer for 5 to 50 minutes, and then a synergistic flame retardant, an initiator and a polyester plasticizer are added and mixed for 5 to 50 minutes. The mixture is then added into a twin-screw extruder, and a masterbatch is obtained through melt extrusion, cooling and granulation.

[0029] The fifth object of the present invention is achieved by the following technical solutions:

[0030] The invention discloses an unsaturated polyester resin-based halogen-free flame retardant material for use in the fields of electronic appliances, building materials, automobiles, etc.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention synthesizes an intrinsic flame-retardant unsaturated polyester resin prepolymer, introduces a flame-retardant structure into the molecular chain skeleton, avoids the migration problem of traditional flame retardants, and improves the flame-retardant stability of the material; and the flame-retardant structure is tightly combined with the resin matrix and is not easy to lose, thereby ensuring a long-term flame-retardant effect; in addition, the presence of styrene groups on the molecular chain of the intrinsic flame-retardant unsaturated polyester resin prepolymer can be further copolymerized with unsaturated hydroxy fatty acids and synergistic flame retardant IL-BP containing C=C bonds to form a uniformly dispersed flame-retardant network, thereby ensuring uniform dispersion of components and further enhancing the flame-retardant efficiency and mechanical strength of the material.

[0033] 2. The unsaturated double bonds and active groups in unsaturated hydroxy fatty acids can further increase the crosslinking density and improve the mechanical properties of the products during the blending process; and the "Al" in the flame retardant Al(OH)3 3+ " can coordinate with the "-COOH" in unsaturated hydroxy fatty acids, increase the intermolecular force and the dispersion effect of the flame retardant, and further enhance the mechanical properties of the material.

[0034] 3. The use of synergistic flame retardant IL-BP significantly reduces the amount of smoke released when the material burns. Black scale nanosheets can form a relatively dense and continuous carbon layer when burning, blocking the transfer of heat and oxygen and inhibiting the generation of combustible gases. The imidazole ring in the ionic liquid produces non-combustible gases such as nitrogen oxides and ammonia during the combustion process, further diluting the concentration of combustible gases and reducing the generation of smoke.

[0035] 4. The present invention in situ polymerizes monomers containing flame retardant elements into unsaturated polyester resins, and simultaneously adds modified flame retardants containing unsaturated double bonds, unsaturated hydroxy fatty acids and other components, which can effectively improve the flame retardant properties and mechanical properties of the material. DETAILED DESCRIPTION

[0036] The technical scheme of the present invention is further described below by specific embodiments. It should be understood that the specific embodiments described herein are only used to help understand the present invention and are not intended for specific limitations of the present invention. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0037] A. The intrinsic flame retardant unsaturated polyester resin prepolymers in Examples 1-3 and Comparative Examples 1-3 are prepared by the following preparation method:

[0038] (1) 0.3 mol of barium hydroxide (Ba(OH)2) was added to 600 mL of deionized water at 60°C, and then 0.3 mol of tetrakis(hydroxymethyl)phosphonium sulfate was gradually added dropwise and the temperature was maintained for 4 hours under stirring. After centrifugation to separate the BaSO4 produced by the reaction, 0.6 mol of 30 wt% hydrogen peroxide solution was slowly added dropwise to the supernatant, and the reaction was carried out at room temperature (30°C) for 5 hours. Then, chloroform was used for extraction and dehydration was performed under reduced pressure to obtain the first-stage product; 50 mL of 30 wt% NaOH solution was slowly added to the first-stage product, and 1.4 g of benzyltriethylammonium chloride as a phase transfer catalyst was slowly added under stirring, and the reaction temperature was maintained at about 35°C. Then, the reaction system was placed in an ice bath, and 0.9 mol of 4-chloro-α-methylstyrene was added dropwise to the above solution, and the reaction was stirred for 3 hours. Then, the temperature was raised to 45°C for 9 hours, and then cooled to room temperature, and washed with deionized water 3 times, and then vacuum dried to obtain a copolymerizable monomer containing a C=C bond. The reaction equation involved in this step is shown in the following formula (I):

[0039]

[0040] 2) 1.05 mol of 1,2-propylene glycol, 0.5 mol of trimethylolpropane and 0.5 mol of maleic anhydride are added to a 250 mL three-necked flask equipped with a mechanical stirrer, a ventilator and a water separator, and xylene is added to remove water by azeotropic distillation and nitrogen is continuously introduced; after reacting at 180° C. for 4 hours, a decompression device with a cold trap, a vacuum gauge, a receiving bottle and a vacuum pump is replaced, and the temperature is maintained constant and the decompression reaction is carried out for 1.5 hours (the decompression pressure is 0.08 MPa), and then the temperature is rapidly lowered to 100° C., and 1.5 mol of the copolymerizable monomer containing a C=C bond prepared in step (1) is added while hot, and after stirring evenly, the mixture is placed at room temperature for 12 hours to obtain an intrinsic flame retardant unsaturated polyester resin prepolymer.

[0041] B. The preparation method of the unsaturated polyester resin prepolymer in Comparative Example 4 is different from that of the intrinsic flame retardant unsaturated polyester resin prepolymer in that no copolymerizable monomer containing a C=C bond is added, specifically:

[0042] 1.05 mol of 1,2-propylene glycol, 0.5 mol of trimethylolpropane and 0.5 mol of maleic anhydride were added into a 250 mL three-necked flask equipped with mechanical stirring, ventilation and water separation devices, and xylene was added to remove water by azeotropic distillation and nitrogen was continuously introduced; after reacting at 180°C for 4 hours, a decompression device with a cold trap, a vacuum gauge, a receiving bottle and a vacuum pump was replaced, and the temperature was maintained constant and the decompression reaction was carried out for 1.5 hours (the decompression pressure was 0.08 MPa) to obtain an unsaturated polyester resin prepolymer.

[0043] C. The IL-BP in Examples 1-3 and Comparative Examples 1-2 and 4 is obtained by the following preparation method:

[0044] (1) Commercially available black scale (BP) was prepared into BP nanosheets by dry ball milling and liquid phase ultrasonic method. Specifically, the commercially available block BP was crushed, then sieved with 200 mesh, and transferred to a planetary ball mill for ball milling at a speed of 350 rpm and a ball-to-powder ratio of 15:1 for 9 h; the ball-milled BP was dispersed in a DMF solution under ice bath conditions, and ultrasonically treated (300 W, 40 kHz) for 1 h, and then centrifuged at 3000 rpm / min for 5 min to obtain a supernatant to remove the unpeeled block BP crystals; finally, the supernatant was further centrifuged at 12,000 rpm for 10 min, and the precipitate was washed three times with deionized water to collect the precipitate; the precipitate was freeze-dried overnight to obtain BP nanosheet powder.

[0045] (2) BP nanosheet powder (0.4 g) was added to DMF solution (200 mL), and then 0.5 g of 1-vinyl-3-methylimidazole methyl sulfate was added, and the mixture was ultrasonically treated (300 W, 40 kHz) in an ice bath for 6 h using an ultrasonic cell grinder; the resulting suspension was centrifuged (3000 rpm / min, 5 min) to remove the detached BP crystals; the supernatant was further centrifuged at 12,000 rpm for 10 min, and washed three times with deionized water to collect the precipitate; the precipitate was freeze-dried for 12 h to obtain IL-BP.

[0046] D. The antioxidant in Examples 1-3 and Comparative Examples 1-4 is a composite antioxidant formed by the antioxidant 168 and the antioxidant 1010 in a mass ratio of 1:1.

[0047] Example 1

[0048] The unsaturated polyester resin-based halogen-free flame retardant material of this embodiment is composed of the following components in parts by weight: 40 parts of intrinsic flame retardant unsaturated polyester resin prepolymer, 10 parts of 3-hydroxy-4-hexenoic acid, 20 parts of aluminum hydroxide, 15 parts of IL-BP, 2 parts of cyclohexanone peroxide, 3 parts of antioxidant, and 10 parts of diethylene glycol dibenzoate.

[0049] According to the formula, the intrinsic flame retardant unsaturated polyester resin prepolymer, 3-hydroxy-4-hexenoic acid, Al(OH)3 and antioxidant were first mixed in a mixer at 500r / min for 30min, then the synergistic flame retardant IL-BP, cyclohexanone peroxide and diethylene glycol dibenzoate were added and mixed at 500r / min for 10min, and then the mixture was added to a twin-screw extruder, and the masterbatch was obtained by melt extrusion, cooling and granulation. Then, the masterbatch was processed into standard specimens by injection molding for performance testing.

[0050] Example 2

[0051] The formula of the unsaturated polyester resin-based halogen-free flame retardant material of Example 2 is shown in Table 1, and the preparation method is the same as that of Example 1.

[0052] Example 3

[0053] The formula of the unsaturated polyester resin-based halogen-free flame retardant material of Example 3 is shown in Table 1, and the preparation method is the same as that of Example 1.

[0054] Comparative Example 1

[0055] The formula of the unsaturated polyester resin-based halogen-free flame retardant material of Comparative Example 1 is shown in Table 1. The difference from Example 1 is that Comparative Example 1 does not add IL-BP, but adds 35 parts of Al(OH)3. Its preparation method is the same as Example 1.

[0056] Comparative Example 2

[0057] The formula of the unsaturated polyester resin-based halogen-free flame retardant material of Comparative Example 2 is shown in Table 1. The difference from Example 3 is that Comparative Example 2 does not add 3-hydroxy-4-hexenoic acid, but adds 61 parts of intrinsic flame retardant unsaturated polyester resin prepolymer. The preparation method is the same as Example 1.

[0058] Comparative Example 3

[0059] The formula of the unsaturated polyester resin-based halogen-free flame retardant material of Comparative Example 3 is shown in Table 1. The difference from Example 1 is that Comparative Example 3 does not add IL-BP, but directly adds 15 parts of unmodified BP nanosheets. The preparation method is the same as Example 1.

[0060] Comparative Example 4

[0061] The formula of the unsaturated polyester resin-based halogen-free flame retardant material of Comparative Example 4 is shown in Table 1. The difference from Example 3 is that Comparative Example 4 does not add intrinsic flame retardant unsaturated polyester resin prepolymer, but directly adds 40 parts of unsaturated polyester resin prepolymer. The preparation method is the same as Example 1.

[0062] Table 1 Formulas of unsaturated polyester resin-based halogen-free flame retardant materials of Examples and Comparative Examples

[0063]

[0064] The samples of Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests using the following method. The results are shown in Table 2.

[0065] Oxygen index test: According to GB / T 2406-1993 standard, the limiting oxygen index (LOI) of flame retardant composite materials is measured, and the sample size is: 110×6.5×3mm. Horizontal combustion test: According to GB / T 2408-1996 standard, the horizontal combustion level of flame retardant composite materials is measured, and the sample size is: 125×13.0×3.0mm. Mechanical properties test: According to GB / T 7594-1987 standard, the mechanical properties of flame retardant composite materials are measured.

[0066] Table 2 Performance results of unsaturated polyester resin-based halogen-free flame retardant materials of Examples and Comparative Examples

[0067]

[0068] It can be seen from Examples 1-3 in Table 2 that the unsaturated polyester resin-based halogen-free flame retardant materials prepared by the present invention all achieve V-0 flame retardancy, and the use of intrinsic flame retardant unsaturated polyester resin prepolymer as raw material, and the addition of flame retardant Al(OH)3 and synergistic flame retardant IL-BP can significantly improve the flame retardant effect of the material. By comparing Example 1 and Example 3, it can be seen that the increase of synergistic flame retardant IL-BP can reduce the amount of smoke released when the material burns, because the phosphoric anhydride produced by the phosphorus-based flame retardant and the ionic liquid during the combustion process can promote the dehydration and carbonization of the combustibles, thereby preventing or delaying the generation of combustible gases.

[0069] It can be seen from Example 1 and Comparative Example 1 that although the use of a high ratio of Al(OH)3 can achieve the same flame retardant effect, this will significantly reduce the mechanical strength of the material and produce a high amount of smoke when burning, affecting the use effect. 3+ Produce coordination effect, this covalent effect can provide better stability to improve the mechanical strength of the product. It can be seen from Example 1 and Comparative Example 3 that the BP nanosheets that have not been modified with ionic liquids as synergistic flame retardants have reduced flame retardant properties and will produce higher smoke. It can be seen from Example 1 and Comparative Example 4 that the flame retardant properties of the material prepared using the unsaturated polyester resin prepolymer that has not been flame retardant modified as the matrix are greatly reduced, and the mechanical properties are also reduced to a certain extent, indicating that the intrinsic flame retardant unsaturated polyester resin prepolymer prepared by the present invention introduces a flame retardant structure into the molecular chain skeleton, which can not only effectively improve the flame retardant properties of the material, but also is conducive to the improvement of mechanical properties.

[0070] The various aspects, embodiments, and features of the present invention should be considered to be illustrative in all aspects and not limiting of the present invention, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0071] In the preparation method of the present invention, the order of each step is not limited to the order listed. For those skilled in the art, without creative work, the order of each step is also within the protection scope of the present invention. In addition, two or more steps or actions can be performed simultaneously.

[0072] Finally, it should be noted that the specific embodiments described herein are merely examples of the present invention, and are not intended to limit the implementation methods of the present invention. A person skilled in the art of the present invention may make various modifications or supplements to the specific embodiments described, or replace them in a similar manner. It is not necessary and impossible to provide all examples of all implementation methods here. However, these obvious changes or modifications derived from the essential spirit of the present invention still fall within the scope of protection of the present invention, and interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims

1. A method for preparing an intrinsic flame retardant unsaturated polyester resin prepolymer, characterized in that: The following steps are involved: (1) reacting barium hydroxide and tetrakis(hydroxymethyl)phosphonium sulfate at 40-80° C. for 1-10 hours, and centrifuging to obtain a supernatant; adding a hydrogen peroxide solution dropwise to the supernatant, and reacting at 10-50° C. for 1-10 hours after the addition is complete, and extracting and decompressing to obtain the first step product; Adding a basic compound and a phase transfer catalyst to the product of the first step, and then adding 4-chloro-α-methylstyrene to react to obtain a copolymerizable monomer containing a C=C bond; (2) 1,2-propylene glycol, trimethylolpropane and maleic anhydride are reacted at 150-200° C. under an inert atmosphere for 1-10 hours, and then the temperature is maintained to continue the reduced pressure reaction for 0.5-5 hours. After the temperature is reduced to 90-120° C., the copolymerizable monomer containing a C=C bond of step (1) is added, and the mixture is stirred evenly to obtain an intrinsic flame retardant unsaturated polyester resin prepolymer.

2. The preparation method according to claim 1, characterized in that: The molar ratio of tetrakis(hydroxymethyl)phosphonium sulfate to barium hydroxide is 0.8 to 1.2:1; The molar ratio of tetrakis(hydroxymethyl)phosphonium sulfate to hydrogen peroxide is 1:1 to 3; The phase transfer catalyst is one or more of tetrabutylammonium bromide, benzyltriethylammonium chloride, and hexadecyltrimethylammonium bromide; The molar ratio of 4-chloro-α-methylstyrene to the product of the first step is 3 to 4:1; The molar ratio of 1,2-propylene glycol, trimethylolpropane and maleic anhydride is 1:0.3-0.7:0.3-0.7 The molar ratio of the copolymerizable monomer containing a C=C bond to maleic anhydride is 1 to 5:

1.

3. An unsaturated polyester resin-based halogen-free flame retardant material, characterized in that: It comprises the following components in parts by weight: 30 to 50 parts of the intrinsic flame-retardant unsaturated polyester resin prepolymer prepared by the preparation method according to claim 1, 5 to 20 parts of unsaturated hydroxy fatty acid, 10 to 40 parts of flame retardant aluminum hydroxide, 5 to 20 parts of synergistic flame retardant, 1 to 2 parts of initiator, 1 to 3 parts of antioxidant, and 5 to 10 parts of polyester plasticizer.

4. The unsaturated polyester resin-based halogen-free flame retardant material according to claim 1, characterized in that: The selected unsaturated hydroxy fatty acid is 3-hydroxy-4-hexenoic acid; The synergistic flame retardant is a black scale nanosheet modified by the non-covalent action of an ionic liquid.

5. The unsaturated polyester resin-based halogen-free flame retardant material according to claim 4, characterized in that: The method for preparing black scale nanosheets modified by non-covalent action of ionic liquid comprises the following steps: preparing black scale into black scale nanosheets by dry ball milling and / or liquid phase ultrasonic method; adding the black scale nanosheets into an organic solvent, then adding the ionic liquid, ultrasonically treating for 1 to 10 hours, then centrifuging for the first time to remove the detached black scale crystals, centrifuging the supernatant for the second time, collecting the precipitate, and drying to obtain IL-BP.

6. The unsaturated polyester resin-based halogen-free flame retardant material according to claim 4 or 5, characterized in that: The ionic liquid is one or more of 1,3-dimethylimidazolium methyl sulfate, 1-vinyl-3-methylimidazolium methyl sulfate, 1,3-dimethylimidazolium nitrate, 1-vinyl-3-methylimidazolium nitrate, 1,3-dimethylimidazolium methanesulfonate, and 1-ethyl-3-methylimidazolium methanesulfonic acid.

7. The unsaturated polyester resin-based halogen-free flame retardant material according to claim 5, characterized in that: The mass ratio of black scale nanosheets to ionic liquid is 1:0.5-3; The speed of the first centrifugation is 1000-5000 rpm / min, and the centrifugation time is 1-6 min; the speed of the second centrifugation is 9000-15000 rpm / min, and the centrifugation time is 8-15 min.

8. The unsaturated polyester resin-based halogen-free flame retardant material according to claim 3, characterized in that: The initiator includes one or more of a peroxide compound initiator and an azo initiator; The antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant; The polyester plasticizer is one or more of diethylene glycol dibenzoate and phthalate plasticizers.

9. The method for preparing an unsaturated polyester resin-based halogen-free flame retardant material according to claim 3, characterized in that: The following steps are involved: The intrinsic flame retardant unsaturated polyester resin prepolymer, unsaturated hydroxy fatty acid, flame retardant aluminum hydroxide and antioxidant are mixed in a mixer for 5 to 50 minutes, and then a synergistic flame retardant, an initiator and a polyester plasticizer are added and mixed for 5 to 50 minutes. The mixture is then added into a twin-screw extruder, and a masterbatch is obtained through melt extrusion, cooling and granulation.

10. Use of the unsaturated polyester resin-based halogen-free flame retardant material according to claim 3 in the fields of electronic appliances, building materials and automobiles.

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