Flame-retardant SMC (Sheet Molding Compound) material for new energy storage box and preparation method thereof

Abstract

The invention discloses a flame-retardant SMC (Sheet Molding Compound) material for a new energy storage box and a preparation method of the flame-retardant SMC material, and relates to the field of composite material preparation. The flame-retardant SMC material for the new energy storage box is prepared from the following components in parts by weight: 20-24 parts of epoxy vinyl ester resin, 14-20 parts of unsaturated polyester resin, 5-10 parts of benzoxazine resin, 12-18 parts of a phosphorus-nitrogen synergist, 5-8 parts of an inorganic flame retardant, 5-8 parts of a reinforcing agent and 1-3 parts of other auxiliaries. The phosphorus-nitrogen synergist comprises vinyl modified DOPO (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) and amino modified DOPO, the inorganic flame retardant is prepared from expanded graphite and aluminum hydroxide, and the reinforcing agent is prepared from alkali-free glass fibers and nano magnesium hydroxide. The SMC material prepared by the invention is suitable for being safely used in various environments, and has high flame retardance and excellent mechanical properties.

Description

Technical Field

[0001] The present invention relates to the field of composite material preparation, and in particular to a flame-retardant SMC material for a new energy storage box and a preparation method thereof. Background Art

[0002] The new energy industry is developing rapidly, and new energy storage technology, as a key component, is crucial for improving energy efficiency and ensuring stable grid operation. New energy storage tanks, used to house and protect key components such as battery modules, are a crucial component of energy storage systems. However, due to the heat generated during battery charging and discharging, as well as potential safety hazards such as short circuits and overcharging, new energy storage tanks face the risk of fire. This can not only damage the energy storage equipment but also cause explosions and other serious consequences, threatening human and property safety.

[0003] Currently, conventional SMC materials for new energy storage tanks on the market have numerous shortcomings. First, conventional SMC materials for new energy storage tanks have poor flame retardancy, making them susceptible to fires caused by sparks during use and even releasing toxic gases during combustion, making them difficult to meet environmental and safety requirements. Second, conventional SMC materials for new energy storage tanks have poor mechanical properties. Some materials contain large amounts of inorganic fillers or flame retardants to improve flame retardancy, resulting in increased internal structural defects and an inability to withstand the stress loads of long-term use. Finally, conventional SMC materials for new energy storage tanks suffer from poor compatibility, limiting their overall performance. The resin matrix often exhibits uneven dispersion and phase separation due to polarity differences or insufficient interfacial bonding, weakening the overall consistency of the material and affecting the structural stability and service life of the energy storage tank. Furthermore, existing flame-retardant materials lack the necessary balance between flame retardancy and mechanical properties. While some materials improve flame retardancy, they also degrade mechanical properties such as strength and toughness, making them unable to meet the structural requirements of new energy storage tanks during actual use.

[0004] In summary, in order to solve the above problems, it is of great practical significance to develop an SMC material for new energy energy storage boxes that can effectively improve flame retardant properties and ensure good mechanical properties. Summary of the Invention

[0005] The object of the present invention is to provide a flame retardant SMC material for a new energy storage box and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A flame-retardant SMC material for a new energy storage box comprises, by weight, 20 to 24 parts of epoxy vinyl ester resin, 14 to 20 parts of unsaturated polyester resin, 5 to 10 parts of benzoxazine resin, 12 to 18 parts of phosphorus-nitrogen synergist, 5 to 8 parts of inorganic flame retardant, 5 to 8 parts of reinforcing agent, and 1 to 3 parts of other additives.

[0008] More optimally, the phosphorus-nitrogen synergist includes 6 to 10 parts of vinyl-modified DOPO and 6 to 8 parts of amino-modified DOPO.

[0009] Among them, vinyl-modified DOPO is a three-membered functionalized heterocyclic compound containing phosphorus-nitrogen-sulfur. The molecular skeleton is based on a 1,3,4-thiadiazole ring as the core, and a 6-vinylpyridine ring is connected by a methylene amino group (-CH=N-). DOPO is introduced to form a phosphorus (P)-nitrogen (N)-sulfur (S) conjugated system. It has both the charring ability of phosphorus-based flame retardants and the smoke suppression effect of nitrogen-based flame retardants. It can form a dense carbon layer during combustion to isolate oxygen and inhibit the release of combustible gases. Amino-modified DOPO is based on vinyl-modified DOPO and introduces amino groups to enhance gas-phase flame retardancy. At the same time, a thiol group is introduced to undergo a thiol-ene click reaction with the vinyl group. The thiol group reacts with the epoxy group in the epoxy resin to fix the flame retardant, reduce the loss of the flame retardant, form a uniform cross-linked network, reduce defects, and improve the mechanical properties of the material.

[0010] More optimally, the preparation method of the vinyl-modified DOPO is as follows: 2-amino-1,3,4-thiadiazole is added to anhydrous ethanol, the temperature is set to 48-50°C, the stirring speed is 280-320 rpm, and after dissolution, 6-vinyl-2-pyridinecarboxaldehyde is added, the temperature is set to 78-82°C, and the reaction is carried out for 9-11 hours; DOPO is added, the temperature is set to 78-82°C, the reaction is carried out for 11-13 hours, the mixture is cooled to 24-27°C, filtered, washed, and dried for 10-15 hours to obtain vinyl-modified DOPO.

[0011] More optimally, in the raw materials of the vinyl-modified DOPO, the mass ratio of DOPO, 2-amino-1,3,4-thiadiazole, and 6-vinyl-2-pyridinecarboxaldehyde is (32.4-36.4):(8.1-10.1):(7.6-9.6).

[0012] More optimally, the preparation method of the amino-modified DOPO is: vinyl-modified DOPO, mercaptoethylamine and benzoin dimethyl ether are sequentially added to tetrahydrofuran, and stirred for reaction at room temperature under ultraviolet light for 4 to 8 hours to obtain amino-modified DOPO.

[0013] More optimally, in the raw materials of the amino-modified DOPO, the mass ratio of vinyl-modified DOPO, mercaptoethylamine and benzoin dimethyl ether is (25.4-26.6):(3.4-3.6):(0.2-0.5).

[0014] More optimally, the inorganic flame retardant is composed of expanded graphite and aluminum hydroxide, and the mass ratio of the two is (3-5):(2-3); the reinforcing agent is composed of alkali-free glass fiber and nano magnesium hydroxide, and the mass ratio of the two is (3.8-4.2):(1.2-3.8).

[0015] More optimally, the other auxiliary agents are composed of p-benzoquinone, magnesium oxide, zinc stearate, and dicumyl peroxide, and the mass ratio of the three is (0.2-0.7): (0.3-0.9): (0.3-1.1): (0.1-0.3).

[0016] A method for preparing a flame-retardant SMC material for a new energy storage box comprises the following steps:

[0017] S1-1: Epoxy vinyl ester resin, unsaturated polyester resin, and benzoxazine resin are stirred and mixed to obtain a mixture;

[0018] S1-2: mixing an inorganic flame retardant and a phosphorus-nitrogen synergist to obtain a composite flame retardant filler;

[0019] S1-3: Add the composite flame retardant filler, reinforcing agent and other additives to the mixed material in sequence, set the speed to 550-650 rpm, and stir for 40-50 minutes to obtain a uniform resin paste;

[0020] S1-4: Place glass fiber evenly on one side of a polypropylene film, apply resin paste to the surface, impregnate, degas, compact, mature, cut, peel off the polypropylene film, hot press, and shape to obtain a flame-retardant SMC material.

[0021] More optimally, the aging temperature is 50-80° C., the hot pressing temperature is 150-180° C., and the hot pressing pressure is 15-20 MPa.

[0022] Compared with the prior art, the beneficial effects achieved by the present invention are: by modifying DOPO, introducing specific reactive groups, and constructing a multi-component synergistic flame retardant system, the present invention effectively improves the flame retardancy and mechanical properties of the flame-retardant SMC material for energy storage boxes.

[0023] To enhance flame retardancy, traditional inorganic flame retardants like expanded graphite and aluminum hydroxide exert their flame retardant properties through endothermic decomposition and physical barrier properties. Their combination forms a gradient heat-absorbing network, meeting thermal protection requirements. The nitrogen source in the phosphorus-nitrogen synergist enhances gas dilution, while the phosphorus source strengthens the carbon layer's density, achieving phosphorus-nitrogen synergistic efficiencies. When the inorganic flame retardant and phosphorus-nitrogen synergist are combined, they form a ternary system of "heat absorption and cooling - gas phase inhibition - carbon layer barrier," enhancing free radical capture efficiency, blocking heat transfer pathways, and strengthening the material's flame retardancy. Vinyl-modified DOPO contains phosphorus, nitrogen, and sulfur elements, which further impart good flame retardant properties. The phosphorus heterocycle undergoes a ring-opening reaction with the epoxy group and is grafted to the resin main chain via a COP bond, ensuring that the phosphorus element is evenly distributed in the cross-linked network, avoiding agglomeration and migration precipitation that lead to loose carbon layers and loss of flame retardant components, and accelerating the release of inert gases such as N2 and SO2 in the gas phase; the further modified amino-modified DOPO can condense with benzoxazine resin, and the benzoxazine resin is cured and ring-opened to generate phenolic hydroxyl groups (-OH) and active methylene groups. The amino groups (-NH2) of the amino-modified DOPO condense with the phenolic hydroxyl groups to form CN bonds and hydrogen bonds, participating in the construction of the cross-linked network of the benzoxazine resin and improving the flame retardancy of the overall resin system. At the same time, the SO2 generated by the S element enhances the free radical capture ability, further improving the flame retardant effect.

[0024] In terms of mechanical property improvement, the polar groups in vinyl modified DOPO can form hydrogen bonds with the silanol groups on the surface of alkaline glass fibers, which can enhance the interfacial bonding between the fibers and the resin matrix, reduce the interfacial defects between the fibers and the resin, and enable the alkaline glass fibers to transfer loads more effectively when subjected to stress, thereby improving the mechanical properties of SMC materials. At the same time, it also promotes the dispersion of expanded graphite in the inorganic flame retardant in the resin matrix, reduces the agglomeration of expanded graphite, and synergistically forms an efficient heat and oxygen insulation layer, so that it can still maintain good mechanical properties while being flame retardant, overcoming the problems of traditional alkaline glass fibers and expanded graphite dispersion. In addition, the polar groups of amino-modified DOPO improve the dispersibility of inorganic flame retardants such as expanded graphite and aluminum hydroxide through electrostatic repulsion and steric hindrance effects, so that they form a uniform "heat absorption-barrier" network in the resin. The thiol group introduced in the amino-modified DOPO can also undergo a thiol-epoxy addition reaction with epoxy vinyl ester resin, introducing sulfide bonds and hydroxyl groups, increasing the activity of the molecular chain, improving the flexibility of the resin, and reducing the possibility of the material breaking when subjected to external force impact. The three synergistically "flame retardant-enhancing-compatible" effects give the SMC material good mechanical properties.

[0025] In terms of improving the compatibility with the resin matrix, the vinyl group introduced by the vinyl-modified DOPO in the phosphorus-nitrogen synergist undergoes a free radical copolymerization reaction with the epoxy vinyl ester resin to form a cross-linked structure, and at the same time copolymerizes with the double bonds in the unsaturated polyester resin, effectively enhancing the compatibility between the resin matrices, and undergoing cycloaddition or free radical reaction with the benzoxazine resin, participating in the construction of the resin curing network and improving the overall cross-linking density; the amino group of the further modified amino-modified DOPO can undergo an amine-epoxy curing reaction with the epoxy group in the epoxy vinyl ester resin, and the ester group in the unsaturated polyester resin combines with the amino group to improve the compatibility. The amino group undergoes a condensation reaction with the phenolic hydroxyl group, enhancing the chemical cross-linking between the resins and further improving the compatibility and dispersibility of the resin.

[0026] In summary, the present invention successfully overcomes the shortcomings of traditional SMC materials by modifying DOPO, effectively improves the flame retardancy and mechanical properties of SMC materials, and has important practical significance. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] It should be noted that the following parts are calculated by weight, and the purchase manufacturers of all raw materials involved in the present invention are exemplified without any special restrictions: in the following examples, epoxy vinyl ester resin (TM-V511), unsaturated polyester resin (TC-191DC), benzoxazine resin (BZ-1201), 2-amino-1,3,4-thiadiazole (CAS: 4005-51-0), 6-vinyl-2-pyridinecarboxaldehyde (CAS: 579500-16-6), DOPO (CAS: 35948-25-5), tetrahydrofuran (CAS: 68-12-2), mercaptoethylamine ( CAS: 60-23-1), dimethyl benzoate (CAS: 24650-42-8), dicumyl peroxide (CAS: 80-43-3), cycloaliphatic amine (CAS: 6864-37-5), nano-magnesium hydroxide (50nm), aluminum hydroxide (CAS: 21645-51-2), melamine polyphosphate (CAS: 15541-60-3), alkali-free glass fiber (single filament diameter 13μm), expanded graphite (50 mesh), p-benzoquinone (CAS: 2237-14-1), magnesium oxide (XP103), zinc stearate (CAS: 557-05-1).

[0029] Example 1: A flame-retardant SMC material for a new energy storage box, comprising the following steps:

[0030] I. Preparation of vinyl-modified DOPO: 9.1 parts of 2-amino-1,3,4-thiadiazole were added to anhydrous ethanol, the temperature was set to 49°C, and the stirring speed was 300 rpm. After dissolution, 8.6 parts of 6-vinyl-2-pyridinecarboxaldehyde were added, the temperature was set to 82°C, and the reaction was carried out for 11 hours. 34.4 parts of DOPO were added, the temperature was set to 82°C, and the reaction was carried out for 12 hours. The mixture was cooled to 26°C, filtered, washed, and dried for 13 hours to obtain vinyl-modified DOPO.

[0031] 2. Preparation of amino-modified DOPO: 26 parts of vinyl-modified DOPO, 3.5 parts of mercaptoethylamine, and 0.35 parts of benzoin dimethyl ether were added to tetrahydrofuran in sequence, and stirred for reaction at room temperature under ultraviolet light for 6 hours to obtain amino-modified DOPO.

[0032] 3. Preparation of SMC materials for new energy storage boxes:

[0033] S1-1: 22 parts of epoxy vinyl ester resin, 17 parts of unsaturated polyester resin, and 7.5 parts of benzoxazine resin were stirred and mixed to obtain a mixture;

[0034] S1-2: 4 parts of expanded graphite, 2.5 parts of aluminum hydroxide, 8 parts of vinyl-modified DOPO, and 7 parts of amino-modified DOPO were mixed to obtain a composite flame retardant filler;

[0035] S1-3: Add composite flame retardant filler, 4 parts of alkali-free glass fiber, 2.4 parts of nano magnesium hydroxide, 0.45 parts of p-benzoquinone, 0.6 parts of magnesium oxide, 0.7 parts of zinc stearate, and 0.2 parts of dicumyl peroxide to the mixture in sequence, set the speed to 600 rpm, and stir for 45 minutes to obtain a uniform resin paste;

[0036] S1-4: Glass fiber with a density of 1.5g / cm 2 Evenly place it on one side of the polypropylene film, apply the resin paste on the surface, impregnate, defoam, compact, set the temperature to 65℃ for aging, cut, peel off the polypropylene film, hot press at 165℃, 18MPa, and shape to obtain the flame retardant SMC material.

[0037] Example 2: A flame-retardant SMC material for a new energy storage box, comprising the following steps:

[0038] I. Preparation of vinyl-modified DOPO: 10.1 parts of 2-amino-1,3,4-thiadiazole were added to anhydrous ethanol, the temperature was set to 50°C, and the stirring speed was 320 rpm. After dissolution, 9.6 parts of 6-vinyl-2-pyridinecarboxaldehyde were added, the temperature was set to 82°C, and the reaction was carried out for 11 hours. 36.4 parts of DOPO were added, the temperature was set to 82°C, and the reaction was carried out for 13 hours. The mixture was cooled to 27°C, filtered, washed, and dried for 15 hours to obtain vinyl-modified DOPO.

[0039] 2. Preparation of amino-modified DOPO: 26.6 parts of vinyl-modified DOPO, 3.6 parts of mercaptoethylamine, and 0.5 parts of benzoin dimethyl ether were added to tetrahydrofuran in sequence, and stirred for reaction at room temperature under ultraviolet light for 8 hours to obtain amino-modified DOPO.

[0040] 3. Preparation of SMC materials for new energy storage boxes:

[0041] S1-1: 24 parts of epoxy vinyl ester resin, 20 parts of unsaturated polyester resin, and 10 parts of benzoxazine resin were stirred and mixed to obtain a mixture;

[0042] S1-2: 5 parts of expanded graphite, 3 parts of aluminum hydroxide, 10 parts of amino-modified DOPO, and 8 parts of amino-modified DOPO were mixed to obtain a composite flame retardant filler;

[0043] S1-3: Add composite flame retardant filler, 4.2 parts of alkali-free glass fiber, 3.8 parts of nano-magnesium hydroxide, 0.7 parts of p-benzoquinone, 0.9 parts of magnesium oxide, 1.1 parts of zinc stearate, and 0.3 parts of dicumyl peroxide to the mixture in sequence, set the speed to 650 rpm, and stir for 50 minutes to obtain a uniform resin paste;

[0044] S1-4: Glass fiber with a density of 1.5g / cm 2 Evenly place it on one side of the polypropylene film, apply the resin paste on the surface, impregnate, defoam, compact, set the temperature to 80℃ for aging, cut, peel off the polypropylene film, hot press at 180℃, 20MPa, and shape to obtain the flame retardant SMC material.

[0045] Example 3: A flame-retardant SMC material for a new energy storage box, comprising the following steps:

[0046] I. Preparation of vinyl-modified DOPO: 8.1 parts of 2-amino-1,3,4-thiadiazole were added to anhydrous ethanol, set the temperature to 48°C, and stirred at 280 rpm. After dissolution, 7.6 parts of 6-vinyl-2-pyridinecarboxaldehyde were added, the temperature was set to 48°C, and the reaction was carried out for 9 hours. 32.4 parts of DOPO were added, the temperature was set to 78°C, and the reaction was carried out for 13 hours. The mixture was cooled to 24°C, filtered, washed, and dried for 10 hours to obtain vinyl-modified DOPO.

[0047] 2. Preparation of amino-modified DOPO: 25.4 parts of vinyl-modified DOPO, 3.4 parts of mercaptoethylamine, and 0.2 parts of benzoin dimethyl ether were added to tetrahydrofuran in sequence, and stirred for reaction at room temperature under ultraviolet light for 4 hours to obtain amino-modified DOPO.

[0048] 3. Preparation of SMC materials for new energy storage boxes:

[0049] S1-1: 20 parts of epoxy vinyl ester resin, 14 parts of unsaturated polyester resin, and 5 parts of benzoxazine resin were stirred and mixed to obtain a mixture;

[0050] S1-2: 3 parts of expanded graphite, 2 parts of aluminum hydroxide, 6 parts of vinyl-modified DOPO, and 6 parts of amino-modified DOPO were mixed to obtain a composite flame retardant filler;

[0051] S1-3: Add composite flame retardant filler, 3.8 parts of alkali-free glass fiber, 1.2 parts of nano-magnesium hydroxide, 0.2 parts of p-benzoquinone, 0.3 parts of magnesium oxide, 0.3 parts of zinc stearate, and 0.1 parts of dicumyl peroxide to the mixture in sequence, set the speed to 550 rpm, and stir for 40 minutes to obtain a uniform resin paste;

[0052] S1-4: Glass fiber with a density of 1.5g / cm 2 Evenly place it on one side of the polypropylene film, apply the resin paste on the surface, impregnate, defoam, compact, set the temperature to 50℃ for aging, cut, peel off the polypropylene film, hot press at 150℃, 15MPa, and shape to obtain the flame retardant SMC material.

[0053] Comparative Example 1: Based on Example 1, the inorganic flame retardant was adjusted, and expanded graphite and aluminum hydroxide were added in a mass ratio of 1:1, specifically comprising the following steps:

[0054] I. Preparation of vinyl-modified DOPO: 9.1 parts of 2-amino-1,3,4-thiadiazole were added to anhydrous ethanol, the temperature was set to 49°C, and the stirring speed was 300 rpm. After dissolution, 8.6 parts of 6-vinyl-2-pyridinecarboxaldehyde were added, the temperature was set to 82°C, and the reaction was carried out for 11 hours. 34.4 parts of DOPO were added, the temperature was set to 82°C, and the reaction was carried out for 12 hours. The mixture was cooled to 26°C, filtered, washed, and dried for 13 hours to obtain vinyl-modified DOPO.

[0055] 2. Preparation of amino-modified DOPO: 26 parts of vinyl-modified DOPO, 3.5 parts of mercaptoethylamine, and 0.35 parts of benzoin dimethyl ether were added to tetrahydrofuran in sequence, and stirred for reaction at room temperature under ultraviolet light for 6 hours to obtain amino-modified DOPO.

[0056] 3. Preparation of SMC materials for new energy storage boxes:

[0057] S1-1: 22 parts of epoxy vinyl ester resin, 17 parts of unsaturated polyester resin, and 7.5 parts of benzoxazine resin were stirred and mixed to obtain a mixture;

[0058] S1-2: 3 parts of expanded graphite, 3 parts of aluminum hydroxide, 8 parts of vinyl-modified DOPO, and 7 parts of amino-modified DOPO were mixed to obtain a composite flame retardant filler;

[0059] S1-3: Add composite flame retardant filler, 4 parts of alkali-free glass fiber, 2.4 parts of nano magnesium hydroxide, 0.45 parts of p-benzoquinone, 0.6 parts of magnesium oxide, 0.7 parts of zinc stearate, and 0.2 parts of dicumyl peroxide to the mixture in sequence, set the speed to 600 rpm, and stir for 45 minutes to obtain a uniform resin paste;

[0060] S1-4: Glass fiber with a density of 1.5g / cm 2 Evenly place it on one side of the polypropylene film, apply the resin paste on the surface, impregnate, defoam, compact, set the temperature to 65℃ for aging, cut, peel off the polypropylene film, hot press at 165℃, 18MPa, and shape to obtain the flame retardant SMC material.

[0061] Comparative Example 2: Based on Example 1, the composition of the phosphorus-nitrogen synergist was adjusted, and a single vinyl-modified DOPO was added, specifically comprising the following steps:

[0062] I. Preparation of vinyl-modified DOPO: 9.1 parts of 2-amino-1,3,4-thiadiazole were added to anhydrous ethanol, the temperature was set to 49°C, and the stirring speed was 300 rpm. After dissolution, 8.6 parts of 6-vinyl-2-pyridinecarboxaldehyde were added, the temperature was set to 82°C, and the reaction was carried out for 11 hours. 34.4 parts of DOPO were added, the temperature was set to 82°C, and the reaction was carried out for 12 hours. The mixture was cooled to 26°C, filtered, washed, and dried for 13 hours to obtain vinyl-modified DOPO.

[0063] 2. Preparation of SMC materials for new energy storage boxes:

[0064] S1-1: 22 parts of epoxy vinyl ester resin, 17 parts of unsaturated polyester resin, and 7.5 parts of benzoxazine resin were stirred and mixed to obtain a mixture;

[0065] S1-2: 4 parts of expanded graphite, 2.5 parts of aluminum hydroxide, 8 parts of vinyl-modified DOPO, and 7 parts of amino-modified DOPO were mixed to obtain a composite flame retardant filler;

[0066] S1-3: Add composite flame retardant filler, 4 parts of alkali-free glass fiber, 2.4 parts of nano magnesium hydroxide, 0.45 parts of p-benzoquinone, 0.6 parts of magnesium oxide, 0.7 parts of zinc stearate, and 0.2 parts of dicumyl peroxide to the mixture in sequence, set the speed to 600 rpm, and stir for 45 minutes to obtain a uniform resin paste;

[0067] S1-4: Glass fiber with a density of 1.5g / cm 2 Evenly place it on one side of the polypropylene film, apply the resin paste on the surface, impregnate, defoam, compact, set the temperature to 65℃ for aging, cut, peel off the polypropylene film, hot press at 165℃, 18MPa, and shape to obtain the flame retardant SMC material.

[0068] Comparative Example 3: Based on Example 1, the composition of the phosphorus-nitrogen synergist was adjusted and a single DOPO was added, specifically comprising the following steps:

[0069] S1-1: 22 parts of epoxy vinyl ester resin, 17 parts of unsaturated polyester resin, and 7.5 parts of benzoxazine resin were stirred and mixed to obtain a mixture;

[0070] S1-2: 4 parts of expanded graphite, 2.5 parts of aluminum hydroxide, and 15 parts of DOPO were mixed to obtain a composite flame retardant filler;

[0071] S1-3: Add composite flame retardant filler, 4 parts of alkali-free glass fiber, 2.4 parts of nano magnesium hydroxide, 0.45 parts of p-benzoquinone, 0.6 parts of magnesium oxide, 0.7 parts of zinc stearate, and 0.2 parts of dicumyl peroxide to the mixture in sequence, set the speed to 600 rpm, and stir for 45 minutes to obtain a uniform resin paste;

[0072] S1-4: Glass fiber with a density of 1.5g / cm 2 Evenly place it on one side of the polypropylene film, apply the resin paste on the surface, impregnate, defoam, compact, set the temperature to 65℃ for aging, cut, peel off the polypropylene film, hot press at 165℃, 18MPa, and shape to obtain the flame retardant SMC material.

[0073] Comparative Example 4: Based on Example 1, the amount of resin matrix added was adjusted to add 14 parts of unsaturated polyester resin, specifically comprising the following steps:

[0074] I. Preparation of vinyl-modified DOPO: 9.1 parts of 2-amino-1,3,4-thiadiazole were added to anhydrous ethanol, the temperature was set to 49°C, and the stirring speed was 300 rpm. After dissolution, 8.6 parts of 6-vinyl-2-pyridinecarboxaldehyde were added, the temperature was set to 82°C, and the reaction was carried out for 11 hours. 34.4 parts of DOPO were added, the temperature was set to 82°C, and the reaction was carried out for 12 hours. The mixture was cooled to 26°C, filtered, washed, and dried for 13 hours to obtain vinyl-modified DOPO.

[0075] 2. Preparation of amino-modified DOPO: 26 parts of vinyl-modified DOPO, 3.5 parts of mercaptoethylamine, and 0.35 parts of benzoin dimethyl ether were added to tetrahydrofuran in sequence, and stirred for reaction at room temperature under ultraviolet light for 6 hours to obtain amino-modified DOPO.

[0076] 3. Preparation of SMC materials for new energy storage boxes:

[0077] S1-1: 22 parts of epoxy vinyl ester resin, 14 parts of unsaturated polyester resin, and 7.5 parts of benzoxazine resin were stirred and mixed to obtain a mixture;

[0078] S1-2: 4 parts of expanded graphite, 2.5 parts of aluminum hydroxide, 8 parts of vinyl-modified DOPO, and 7 parts of amino-modified DOPO were mixed to obtain a composite flame retardant filler;

[0079] S1-3: Add composite flame retardant filler, 4 parts of alkali-free glass fiber, 2.4 parts of nano magnesium hydroxide, 0.45 parts of p-benzoquinone, 0.6 parts of magnesium oxide, 0.7 parts of zinc stearate, and 0.2 parts of dicumyl peroxide to the mixture in sequence, set the speed to 600 rpm, and stir for 45 minutes to obtain a uniform resin paste;

[0080] S1-4: Glass fiber with a density of 1.5g / cm 2 Evenly place it on one side of the polypropylene film, apply the resin paste on the surface, impregnate, defoam, compact, set the temperature to 65℃ for aging, cut, peel off the polypropylene film, hot press at 165℃, 18MPa, and shape to obtain the flame retardant SMC material.

[0081] Performance Testing: The SMC materials prepared in the Examples and Comparative Examples were subjected to performance testing. According to GB / T 2406.2-2009, "Determination of Combustion Behavior of Plastics by Oxygen Index Method," an oxygen index meter was used to observe the combustion of the molded shell and determine the critical oxygen concentration (OI). According to ISO 5660-1, the heat release rate was measured using a cone calorimeter. Furthermore, according to GB / T 1449-2005, "Fiber-Reinforced Plastics Test Method for Flexural Properties," the flexural strength was measured using a universal material testing machine at a loading speed of 2 mm / min. The data obtained from these performance tests are shown in Table 1:

[0082] Table 1. Performance test data of examples and comparative examples

[0083]

[0084] Conclusion: The performance test data of the examples and the comparative examples are compared. It can be seen from Examples 1-3 that under the synergistic effect of amino-modified DOPO, inorganic flame retardant compound and reinforcement system, the flame retardancy and mechanical properties of the material remain stable and balanced. The phosphorus heterocycle (P=O) in the vinyl-modified DOPO forms a high-efficiency COP bond graft with the epoxy resin, combined with the endothermic cooling and physical barrier of the inorganic flame retardant to form a multi-dimensional flame retardant mechanism, and undergoes cycloaddition with the benzoxazine resin, participating in its curing process to form a denser cross-linked structure, thereby increasing the overall cross-linking density of the SMC material, and increasing the bending strength and oxygen index of the SMC material; the amino group (-NH2) of the amino-modified DOPO undergoes a classic amine-epoxy reaction with the epoxy group (-O-) of the epoxy vinyl ester resin. The amino-modified DOPO reacts to generate CNC bonds and hydroxyl groups (-OH). The amino-modified DOPO introduces flame-retardant functional core groups containing phosphorus (P) and oxygen (O). The nitrogen (N) and sulfur (S) groups form a "phosphorus-nitrogen-sulfur" synergistic flame retardant system with phosphorus, which improves the oxygen index of the SMC material and reduces the heat release efficiency. At the same time, the amino group enhances the interfacial bonding force between the filler and the resin. The multi-level rigid synergistic reinforcement network improves the bending strength of the SMC material, making the performance of the SMC material achieve the best balance and have excellent flame retardancy and mechanical properties.

[0085] Compared with Example 1, Comparative Examples 1-4 have an unbalanced flame retardant ratio, which weakens the synergistic effect with amino-modified DOPO and amino-modified DOPO, resulting in reduced carbon layer structural stability and filler dispersibility, a decreased oxygen index, and an increased heat release rate, resulting in a decrease in the flame retardancy of the SMC material. The lack of amino-modified DOPO and the resulting lack of amino connections lead to a deterioration in the integrity of the SMC material. Traditional single DOPO also reduces the compatibility between the resin matrix, making it difficult to form an effective flame retardant network and material cross-linking, resulting in a decrease in the flame retardancy and mechanical properties of the SMC material. In summary, the examples break through the bottleneck of traditional SMC materials through the innovative formula of "DOPO modification-inorganic flame retardant gradient compounding-enhanced phase interface synergy", achieving comprehensive optimization in oxygen index, heat release rate, and flexural strength.

[0086] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A flame-retardant SMC material for a new energy storage box, characterized by: The raw materials of the SMC material include the following components: by weight, 20 to 24 parts of epoxy vinyl ester resin, 14 to 20 parts of unsaturated polyester resin, 5 to 10 parts of benzoxazine resin, 12 to 18 parts of phosphorus-nitrogen synergist, 5 to 8 parts of inorganic flame retardant, 5 to 8 parts of reinforcing agent, and 1 to 3 parts of other additives.

2. The flame-retardant SMC material for a new energy storage box according to claim 1, characterized in that: The phosphorus-nitrogen synergist includes the following materials in parts by mass: 6 to 10 parts of vinyl-modified DOPO and 6 to 8 parts of amino-modified DOPO.

3. The flame-retardant SMC material for a new energy storage box according to claim 2, characterized in that: The preparation method of the vinyl-modified DOPO comprises: adding 2-amino-1,3,4-thiadiazole to anhydrous ethanol, setting the temperature to 48-50° C., stirring at a speed of 280-320 rpm, adding 6-vinyl-2-pyridinecarboxaldehyde after dissolution, setting the temperature to 78-82° C., and reacting for 9-11 hours; adding DOPO, setting the temperature to 78-82° C., reacting for 11-13 hours, cooling to 24-27° C., filtering, washing, and drying to obtain the vinyl-modified DOPO.

4. The flame-retardant SMC material for a new energy storage box according to claim 2, characterized in that: In the raw materials of the vinyl-modified DOPO, the mass ratio of DOPO, 2-amino-1,3,4-thiadiazole, and 6-vinyl-2-pyridinecarboxaldehyde is (32.4-36.4):(8.1-10.1):(7.6-9.6).

5. The flame-retardant SMC material for a new energy storage box according to claim 2, characterized in that: The preparation method of the amino-modified DOPO comprises the following steps: adding vinyl-modified DOPO, mercaptoethylamine and benzoin dimethyl ether to tetrahydrofuran in sequence, stirring and reacting for 4 to 8 hours at room temperature under ultraviolet light irradiation to obtain the amino-modified DOPO.

6. The flame-retardant SMC material for a new energy storage box according to claim 2, characterized in that: In the raw materials of the amino-modified DOPO, the mass ratio of vinyl-modified DOPO, mercaptoethylamine and benzoin dimethyl ether is (25.4-26.6):(3.4-3.6):(0.2-0.5).

7. The flame-retardant SMC material for a new energy storage box according to claim 1, characterized in that: The inorganic flame retardant is composed of expanded graphite and aluminum hydroxide, and the mass ratio of the two is (3-5):(2-3); the reinforcing agent is composed of alkali-free glass fiber and nano magnesium hydroxide, and the mass ratio of the two is (3.8-4.2):(1.2-3.8).

8. The flame-retardant SMC material for a new energy storage box according to claim 1, characterized in that: The other auxiliary agents are composed of p-benzoquinone, magnesium oxide, zinc stearate and dicumyl peroxide, and the mass ratio of the three is (0.2-0.7): (0.3-0.9): (0.3-1.1): (0.1-0.3).

9. The method for preparing a flame-retardant SMC material for a new energy storage box according to claim 1, characterized in that: The following steps are involved: S1-1: Epoxy vinyl ester resin, unsaturated polyester resin, and benzoxazine resin are stirred and mixed to obtain a mixture; S1-2: mixing an inorganic flame retardant and a phosphorus-nitrogen synergist to obtain a composite flame retardant filler; S1-3: Add the composite flame retardant filler, reinforcing agent and other additives to the mixed material in sequence, set the speed to 550-650 rpm, and stir for 40-50 minutes to obtain a uniform resin paste; S1-4: Place glass fiber evenly on one side of a polypropylene film, apply resin paste to the surface, impregnate, degas, compact, mature, cut, peel off the polypropylene film, hot press, and shape to obtain a flame-retardant SMC material.

10. The method for preparing a flame-retardant SMC material for a new energy energy storage box according to claim 9, characterized in that: The aging temperature is 50-80° C., the hot pressing temperature is 150-180° C., and the hot pressing pressure is 15-20 MPa.

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