Expandable graphite polystyrene particles and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to expandable graphite polystyrene particles and a preparation method thereof. The expandable graphite polystyrene particles mainly comprise the following components: deionized water, calcium phosphate, an auxiliary dispersant, styrene, modified styrene, graphite powder, kaolin, an initiator, a nucleating agent, a plasticizer and a foaming agent. The functional monomer is prepared through a two-step method, then styrene, the functional monomer, graphite powder, kaolin and other raw materials are compounded, and the expandable graphite polystyrene particles with excellent comprehensive performance are prepared through mutual cooperation of physical mixing, free radical polymerization, foaming and other effects.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to expandable graphite polystyrene particles and a preparation method thereof. Background Art

[0002] Expandable graphite polystyrene is a new type of high-performance thermal insulation material. By introducing graphite particles into the polystyrene matrix, the thermal insulation and flame retardancy of the material are significantly improved. The addition of graphite enables polystyrene to have a higher heat reflection ability, effectively reducing heat conduction, while enhancing the mechanical strength and dimensional stability of the material. Graphite-modified polystyrene not only retains the advantages of traditional polystyrene such as light weight and easy processing, but also has made breakthroughs in fire resistance and can meet more stringent building fire protection standards. In addition, its environmental protection characteristics have also been improved, and some products can be recycled, meeting the requirements of sustainable development. With the increasing demand for building energy conservation, expandable graphite polystyrene has been widely used in wall insulation, roof insulation and other fields.

[0003] The patent with application number CN202210436099.4 provides a composite graphite flame-retardant polystyrene beads and a preparation method thereof. By adding cage-type polysilsesquioxane (POSS) as a cross-linking agent in the reactor, POSS is compounded with the polymer matrix by copolymerization, grafting or blending, and the combustion characteristics are significantly delayed. At the same time, methyl octabromoether is added to further improve the flame retardancy. The composite graphite is composed of graphite, graphitized carbon black and a modifier. The modifier is a titanate coupling agent or polyvinyl pyrrolidone (PVP), which changes the surface activity of graphite and carbon black, so that the composite graphite and styrene monomer are evenly fused to form highly dispersed droplets, ensuring product uniformity. The use of physical foaming agent fluorocarbon compounds improves the foaming multiple and foam stability. The polystyrene beads prepared by this method have excellent thermal conductivity, compressive strength and flame retardant properties, meet the fire protection requirements of building materials, and are suitable for building insulation structures. The patent with application number CN202310850208.1 provides a graphite composite polystyrene particles and a preparation method thereof. The main raw materials include styrene, water, graphite, foaming agent, initiator, nucleating agent, modified magnesium hydroxide, trisodium phosphate, inorganic suspending agent, organic suspending agent and polydifluoropropylmethylsiloxane. The invention improves the flame retardant properties of polystyrene particles by adding modified magnesium hydroxide and graphite, and at the same time improves the dispersibility of graphite by polydifluoropropylmethylsiloxane, thereby improving the compressive strength and flame retardant properties of the particles. The polystyrene particles provided by the above inventions have good strength and flame retardant properties, but their antioxidant and chemical resistance are poor. Insufficient antioxidant properties will make the material prone to oxidative degradation under high temperature or long-term exposure to air, resulting in molecular chain breakage and decreased material performance, such as reduced strength and poor toughness, affecting its reliability as a structural material. Insufficient chemical resistance means that the material is prone to swelling, dissolution or chemical reactions when in contact with chemical substances such as acids, alkalis, and solvents, resulting in material structural damage and loss of performance. This not only limits its application in chemical environments, but also causes safety hazards. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an expandable graphite polystyrene particle and a preparation method thereof. A functional monomer is prepared by a two-step method, and the functional monomer is compounded with raw materials such as styrene, graphite powder, and kaolin. This not only improves the material's UV resistance, antioxidant, heat resistance, flame retardancy, and chemical resistance at the molecular level, but also achieves a comprehensive improvement in the material's comprehensive performance through the synergistic effect between the components.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: An expandable graphite polystyrene particle comprises the following components, measured by weight: 120-150 parts of deionized water, 0.2-0.4 parts of calcium phosphate, 0.05-0.15 parts of auxiliary dispersant, 65-95 parts of styrene, 10-15 parts of functional monomer, 2-5 parts of graphite powder, 0.1-0.2 parts of kaolin, 0.2-0.5 parts of initiator, 1-2 parts of nucleating agent, 0.3-0.7 parts of plasticizer, and 3-6 parts of foaming agent; The preparation method of the functional monomer is as follows: Step S1: 2-(3,4-difluorophenyl)ethylene oxide, 4-vinylphenylacetic acid, chromium acetate and toluene are uniformly mixed, and then the temperature is raised to 90-110° C. under stirring conditions, and the reaction is carried out for 6-8 hours. After cooling and purification, an intermediate is obtained; Step S2: 2-(1-benzotriazole)acetic acid, the intermediate, p-toluenesulfonic acid and N,N-dimethylformamide are uniformly mixed, the temperature is raised to 60-80° C. under stirring conditions, the reaction is performed for 5-7 hours, and after cooling and purification, a functional monomer is obtained; The synthetic route of the functional monomer is as follows: ; .

[0006] The present invention uses 2-(3,4-difluorophenyl)ethylene oxide and 4-vinylphenylacetic acid as starting materials, and an epoxy compound ring-opening reaction occurs under the catalysis of chromium acetate to obtain an intermediate; then the intermediate and 2-(1-benzotriazole)acetic acid are used as raw materials, and an esterification reaction occurs under the action of p-toluenesulfonic acid to obtain a functional monomer. The present invention uses a two-step method to introduce benzotriazole and fluorine elements into the molecular structure of the functional monomer, and then compound raw materials such as styrene, functional monomers, graphite powder, kaolin, etc., and cooperate with each other through physical mixing, free radical polymerization, foaming and other effects to obtain expandable graphite polystyrene particles.

[0007] In order to obtain functional monomers and ensure product consistency, the molar ratio of 2-(3,4-difluorophenyl)ethylene oxide, 4-vinylphenylacetic acid, and chromium acetate in step S1 is 1.4:1.3-1.5:0.02-0.03, and the mass volume ratio of 2-(3,4-difluorophenyl)ethylene oxide and toluene is 0.1-0.3 g / mL; the molar ratio of 2-(1-benzotriazole)acetic acid, intermediate, and p-toluenesulfonic acid in step S2 is 1.7:1.5-1.7:0.06-0.10, and the mass volume ratio of 2-(1-benzotriazole)acetic acid and N,N-dimethylformamide is 0.2-0.4 g / mL.

[0008] Furthermore, the initiator is one or more of azobisisobutyronitrile, dibenzoyl peroxide, diisopropyl peroxide, and tert-butyl perbenzoate; the auxiliary dispersant is prepared by mixing equal masses of hydroxypropyl cellulose and hexadecyltrimethylammonium bromide; the nucleating agent is polyethylene wax; the plasticizer is prepared by mixing xylene and white oil; and the foaming agent is n-pentane or cyclopentane.

[0009] The present invention also provides a method for preparing expandable graphite polystyrene particles, comprising the following steps: adding calcium phosphate and an auxiliary dispersant to deionized water, adding kaolin after mixing evenly, stirring for 10-30 minutes, then adding graphite powder, continuing to stir for 10-30 minutes, then adding styrene, functional monomers, initiators, nucleating agents, and plasticizers, stirring evenly, raising the temperature to 88-92°C, reacting for 4-6 hours, finally adding a foaming agent and calcium carbonate, stirring evenly, continuing to raise the temperature to 125-130°C, continuing to react for 2-4 hours, cooling down, separating the solid and the liquid, washing, and drying the solid to obtain the polystyrene particles.

[0010] The present invention has the following beneficial effects: The present invention compounds functional monomers with raw materials such as styrene, graphite powder, and kaolin, and cooperates with each other through physical mixing, free radical polymerization, foaming, etc. to obtain expandable graphite polystyrene particles, and introduces benzotriazole and fluorine elements into the polystyrene particles. The introduction of benzotriazole provides excellent ultraviolet absorption performance for polystyrene molecules, and the nitrogen heterocyclic ring in the benzotriazole structure can absorb ultraviolet light and convert it into heat energy, thereby reducing the damage of ultraviolet light to the polystyrene molecular chain. This mechanism of action effectively delays the aging process of the material under ultraviolet light irradiation and improves the anti-ultraviolet performance of the material. The introduction of fluorine significantly improves the chemical resistance and flame retardancy of polystyrene. Fluorine has extremely high electronegativity and chemical inertness, and can form a dense fluorinated layer on the surface of the polystyrene molecular chain. This fluorinated layer can effectively block the erosion of oxygen, moisture and chemical media, making the polystyrene material have excellent chemical corrosion resistance; fluorine-containing substances can also release fluorine free radicals at high temperatures, which can combine with active free radicals generated during the combustion process to interrupt the combustion chain reaction, thereby improving the flame retardancy of the material. In addition, the nitrogen atom in benzotriazole has a lone pair of electrons, which can react with free radicals, capture the free radicals generated by polystyrene during the oxidation process, terminate the chain oxidation reaction, and inhibit the oxidation process; the high electronegativity of fluorine makes the CF bond very stable, reduces the weak sites on the polymer molecular chain that are easily oxidized, and enhances the resistance of polystyrene materials to oxidants such as oxygen. The two work together to significantly improve the antioxidant properties of polystyrene.

[0011] In the process of compounding functional monomers with other raw materials (such as styrene, graphite powder, kaolin, etc.), the synergistic effect further improves the comprehensive performance of polystyrene materials. Graphite powder has excellent thermal conductivity and heat resistance, and can form a thermal conductive network in the polystyrene matrix to accelerate the diffusion of heat, thereby improving the heat resistance of the material. At the same time, the lamellar structure of graphite powder can effectively block the penetration of oxygen, and synergize with functional monomers and other raw materials to effectively delay the oxidative degradation process of the material. Kaolin has light scattering properties and can reduce direct ultraviolet light. Its surface active sites can interact with the groups in benzotriazole to synergistically improve the anti-ultraviolet performance of polystyrene materials; in terms of flame retardancy, kaolin can cooperate with the fluorinated layer formed by fluorine elements and the released fluorine free radicals through physical barriers, capturing free radicals, and promoting carbonization reactions, thereby enhancing the flame retardant effect. In addition, the use of auxiliary dispersants ensures the uniform dispersion of each component in the polystyrene matrix, avoiding the problem of uneven performance caused by excessive local concentration; initiators and nucleating agents optimize the microstructure of the material by regulating the rate of polymerization reaction and crystallization process, making it more compact and uniform; the addition of plasticizers and foaming agents further improves the processing performance and lightweight characteristics of the material.

[0012] In summary, the present invention introduces benzotriazole and fluorine elements into the molecular structure of functional monomers through a two-step method, and compounding the functional monomers with raw materials such as styrene, graphite powder, and kaolin, which not only improves the material's UV resistance, antioxidant, heat resistance, flame retardancy, and chemical resistance at the molecular level, but also achieves a comprehensive improvement in the material's comprehensive performance through the synergistic effect between the components. This multi-level modification strategy provides an important theoretical basis and technical support for the development of high-performance polystyrene materials. DETAILED DESCRIPTION

[0013] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0014] Graphite powder, mesh number 325, density 2.35g / cm³, fixed carbon 99.7%, brand Yongshun; kaolin, particle size 1-3μm, density 1.7g / cm³, effective content 98%, hardness 5.5HB, brand Qingjiang; hydroxypropyl cellulose, density 0.5g / mL at25°C (lit.) g / mL, melting point 371.06℃, brand Lifan; polyethylene wax, model Q-18PE wax, effective ingredient content 99%, brand Xindongyi; white oil, model No. 5, specific gravity 0.86, flash point 140℃, brand Shengda Chemical. The raw materials used in the following examples are all common commercially available products.

[0015] Embodiment 1: An expandable graphite polystyrene particle comprises the following components in parts by weight: 130 parts of deionized water, 0.3 parts of calcium phosphate, 0.1 parts of auxiliary dispersant, 80 parts of styrene, 12 parts of functional monomer, 3 parts of graphite powder, 0.15 parts of kaolin, 0.4 parts of initiator, 1.5 parts of nucleating agent, 0.5 parts of plasticizer, and 5 parts of foaming agent; wherein the auxiliary dispersant is prepared by mixing equal masses of hydroxypropyl cellulose and hexadecyltrimethylammonium bromide, the initiator is azobisisobutyronitrile, the nucleating agent is polyethylene wax, the plasticizer is prepared by mixing xylene and white oil in a weight ratio of 1:2, and the foaming agent is n-pentane; The preparation method of the functional monomer is: Step S1: 2-(3,4-difluorophenyl)ethylene oxide, 4-vinylphenylacetic acid, chromium acetate and toluene are mixed uniformly, and then the temperature is raised to 100° C. under stirring conditions, and the reaction is carried out for 7 hours. After the reaction is completed, the heating is stopped, and the mixture is naturally cooled to room temperature, filtered, and the filtrate is taken. Toluene is removed by vacuum distillation, and ethyl acetate and water are added for extraction (the volume ratio of toluene, ethyl acetate and water is 1:1:1), and the mixture is allowed to stand for stratification to separate the organic phase, and the organic phase is rotary evaporated to remove the organic solvent, and then dried with anhydrous sodium sulfate desiccant, and the desiccant is filtered to remove the desiccant to obtain an intermediate; wherein the molar ratio of the 2-(3,4-difluorophenyl)ethylene oxide, 4-vinylphenylacetic acid and chromium acetate is 1.4:1.4:0.025, and the mass volume ratio of the 2-(3,4-difluorophenyl)ethylene oxide and toluene is 0.2 g / mL; Step S2: 2-(1-benzotriazole)acetic acid, intermediate, p-toluenesulfonic acid, and N,N-dimethylformamide are mixed uniformly, the temperature is raised to 70° C. under stirring, and the reaction is carried out for 6 hours. After the reaction is completed, the heating is stopped, the mixture is naturally cooled to room temperature, and an aqueous sodium bicarbonate solution is added, and stirring is continued for 40 minutes. Then, ethyl acetate is added for extraction, and the mixture is allowed to stand for stratification to separate the organic phase. The organic phase is subjected to rotary evaporation to remove the organic solvent, and the organic phase is dried with anhydrous sodium sulfate desiccant, and the desiccant is filtered to remove the desiccant to obtain a functional monomer; wherein the molar ratio of the 2-(1-benzotriazole)acetic acid, intermediate, and p-toluenesulfonic acid is 1.7:1.6:0.08, the mass volume ratio of the 2-(1-benzotriazole)acetic acid and N,N-dimethylformamide is 0.3 g / mL, the mass ratio of the aqueous sodium bicarbonate solution to the p-toluenesulfonic acid is 20:1, the mass fraction of sodium bicarbonate in the aqueous sodium bicarbonate solution is 5%, and the volume ratio of ethyl acetate to the aqueous sodium bicarbonate solution is 1:2; The NMR results of the functional monomer are: 1 H NMR (300MHz, DMSO-d6) δ 8.09 (d, 1H), 7.88 (d, 1H), 7.57-7.62 (m, 3H), 7.38-7.40 (m, 3H), 7.20 (d, 1H), 6.96-7.01 (m, 2H), 6.70-6.73 (m , 1H), 6.56 (t, 1H), 5.74 (d, 1H), 5.21 (d, 1H), 4.78-4.80 (m, 1H), 4.68 (s, 2H), 4.50-4.53 (m, 1H), 3.74 (s, 2H).

[0016] A preparation method of expandable graphite polystyrene particles comprises the following steps: adding calcium phosphate and an auxiliary dispersant to deionized water, adding kaolin after mixing evenly, stirring for 20 minutes, adding graphite powder, continuing to stir for 20 minutes, then adding styrene, functional monomers, initiators, nucleating agents, and plasticizers, stirring evenly, raising the temperature to 90°C, reacting for 5 hours, finally adding a foaming agent and calcium carbonate, stirring evenly, continuing to raise the temperature to 127°C, continuing to react for 3 hours, naturally cooling to below 40°C, separating solid from liquid, taking solid, washing with water, and drying to constant weight to obtain expandable graphite polystyrene particles, wherein the average particle size of the particles is 0.75 mm; wherein the mass ratio of calcium carbonate to the foaming agent is 0.15:8.

[0017] Embodiment 2: An expandable graphite polystyrene particle comprises the following components in parts by weight: 120 parts of deionized water, 0.2 parts of calcium phosphate, 0.05 parts of auxiliary dispersant, 65 parts of styrene, 10 parts of functional monomer, 2 parts of graphite powder, 0.1 parts of kaolin, 0.2 parts of initiator, 1 part of nucleating agent, 0.3 parts of plasticizer, and 3 parts of foaming agent; wherein the auxiliary dispersant is prepared by mixing equal masses of hydroxypropyl cellulose and hexadecyltrimethylammonium bromide, the initiator is dibenzoyl peroxide, the nucleating agent is polyethylene wax, the plasticizer is prepared by mixing xylene and white oil in a weight ratio of 1:2, and the foaming agent is cyclopentane; The preparation method of the functional monomer is: Step S1: 2-(3,4-difluorophenyl)ethylene oxide, 4-vinylphenylacetic acid, chromium acetate and toluene are mixed uniformly, and then the temperature is raised to 110° C. under stirring conditions, and the reaction is carried out for 6 hours. After the reaction is completed, the heating is stopped, and the mixture is naturally cooled to room temperature, filtered, and the filtrate is taken. Toluene is removed by vacuum distillation, and ethyl acetate and water are added for extraction (the volume ratio of toluene, ethyl acetate and water is 1:1:1), and the mixture is allowed to stand for stratification to separate the organic phase, and the organic phase is rotary evaporated to remove the organic solvent, and then dried with anhydrous sodium sulfate desiccant, and the desiccant is filtered to remove the desiccant to obtain an intermediate; wherein the molar ratio of the 2-(3,4-difluorophenyl)ethylene oxide, 4-vinylphenylacetic acid and chromium acetate is 1.4:1.3:0.02, and the mass volume ratio of the 2-(3,4-difluorophenyl)ethylene oxide and toluene is 0.1 g / mL; Step S2: 2-(1-benzotriazole)acetic acid, intermediate, p-toluenesulfonic acid, and N,N-dimethylformamide are mixed uniformly, the temperature is raised to 80° C. under stirring, and the reaction is carried out for 5 hours. After the reaction is completed, the heating is stopped, the mixture is naturally cooled to room temperature, and an aqueous sodium bicarbonate solution is added, and stirring is continued for 40 minutes. Then, ethyl acetate is added for extraction, and the mixture is allowed to stand for stratification to separate the organic phase. The organic phase is rotary evaporated to remove the organic solvent, and the organic phase is dried with anhydrous sodium sulfate desiccant, and the desiccant is filtered to remove the desiccant to obtain a functional monomer; wherein the molar ratio of the 2-(1-benzotriazole)acetic acid, the intermediate, and p-toluenesulfonic acid is 1.7:1.5:0.06, the mass volume ratio of the 2-(1-benzotriazole)acetic acid and N,N-dimethylformamide is 0.2 g / mL, the mass ratio of the aqueous sodium bicarbonate solution to the p-toluenesulfonic acid is 20:1, the mass fraction of sodium bicarbonate in the aqueous sodium bicarbonate solution is 5%, and the volume ratio of ethyl acetate to the aqueous sodium bicarbonate solution is 1:2.

[0018] A preparation method of expandable graphite polystyrene particles comprises the following steps: adding calcium phosphate and an auxiliary dispersant to deionized water, adding kaolin after mixing evenly, stirring for 30 minutes, adding graphite powder, continuing to stir for 30 minutes, then adding styrene, functional monomers, initiators, nucleating agents, and plasticizers, stirring evenly, raising the temperature to 92°C, reacting for 4 hours, finally adding a foaming agent and calcium carbonate, stirring evenly, continuing to raise the temperature to 130°C, continuing to react for 2 hours, naturally cooling to below 40°C, separating solid from liquid, taking solid, washing with water, and drying to constant weight to obtain expandable graphite polystyrene particles, wherein the average particle size of the particles is 0.81 mm; wherein the mass ratio of calcium carbonate to the foaming agent is 0.17:8.

[0019] Embodiment 3: An expandable graphite polystyrene particle, comprising the following components in parts by weight: 150 parts of deionized water, 0.4 parts of calcium phosphate, 0.15 parts of auxiliary dispersant, 95 parts of styrene, 15 parts of functional monomer, 5 parts of graphite powder, 0.2 parts of kaolin, 0.5 parts of initiator, 2 parts of nucleating agent, 0.7 parts of plasticizer, and 6 parts of foaming agent; wherein the auxiliary dispersant is prepared by mixing equal masses of hydroxypropyl cellulose and hexadecyltrimethylammonium bromide, the initiator is diisopropyl peroxide, the nucleating agent is polyethylene wax, the plasticizer is prepared by mixing xylene and white oil in a weight ratio of 1:2, and the foaming agent is n-pentane; The preparation method of the functional monomer is: Step S1: 2-(3,4-difluorophenyl)ethylene oxide, 4-vinylphenylacetic acid, chromium acetate and toluene are mixed uniformly, and then the temperature is raised to 90° C. under stirring conditions, and the reaction is carried out for 8 hours. After the reaction is completed, the heating is stopped, and the mixture is naturally cooled to room temperature, filtered, and the filtrate is taken. Toluene is removed by vacuum distillation, and ethyl acetate and water are added for extraction (the volume ratio of toluene, ethyl acetate and water is 1:1:1). The mixture is allowed to stand for stratification, and the organic phase is separated. The organic phase is subjected to rotary evaporation to remove the organic solvent, and then dried with anhydrous sodium sulfate desiccant, and the desiccant is filtered to remove the desiccant to obtain an intermediate; wherein the molar ratio of the 2-(3,4-difluorophenyl)ethylene oxide, 4-vinylphenylacetic acid and chromium acetate is 1.4:1.5:0.03, and the mass volume ratio of the 2-(3,4-difluorophenyl)ethylene oxide and toluene is 0.3 g / mL; Step S2: 2-(1-benzotriazole)acetic acid, intermediate, p-toluenesulfonic acid and N,N-dimethylformamide are mixed uniformly, the temperature is raised to 60° C. under stirring, the reaction is carried out for 7 hours, after the reaction is completed, the heating is stopped, the mixture is naturally cooled to room temperature, an aqueous sodium bicarbonate solution is added, stirring is continued for 40 minutes, ethyl acetate is added for extraction, the mixture is allowed to stand for stratification, an organic phase is separated, the organic phase is rotary evaporated, the organic solvent is removed, the mixture is dried with anhydrous sodium sulfate desiccant, the desiccant is filtered out, and a functional monomer is obtained; wherein the molar ratio of the 2-(1-benzotriazole)acetic acid, the intermediate and p-toluenesulfonic acid is 1.7:1.7:0.10, the mass volume ratio of the 2-(1-benzotriazole)acetic acid and N,N-dimethylformamide is 0.4 g / mL, the mass ratio of the aqueous sodium bicarbonate solution to the p-toluenesulfonic acid is 20:1, the mass fraction of sodium bicarbonate in the aqueous sodium bicarbonate solution is 5%, and the volume ratio of ethyl acetate to the aqueous sodium bicarbonate solution is 1:2.

[0020] A preparation method of expandable graphite polystyrene particles comprises the following steps: adding calcium phosphate and an auxiliary dispersant to deionized water, adding kaolin after mixing evenly, stirring for 10 minutes, adding graphite powder, continuing to stir for 10 minutes, then adding styrene, functional monomers, initiators, nucleating agents, and plasticizers, stirring evenly, raising the temperature to 88°C, reacting for 6 hours, finally adding a foaming agent and calcium carbonate, stirring evenly, continuing to raise the temperature to 125°C, continuing to react for 4 hours, naturally cooling to below 40°C, separating solid from liquid, taking solid, washing with water, and drying to constant weight to obtain expandable graphite polystyrene particles, wherein the average particle size of the particles is 0.72 mm; wherein the mass ratio of calcium carbonate to the foaming agent is 0.2:8.

[0021] Example 4: An expandable graphite polystyrene particle, comprising the following components in parts by weight: 120 parts of deionized water, 0.25 parts of calcium phosphate, 0.09 parts of auxiliary dispersant, 70 parts of styrene, 12 parts of the functional monomer prepared in Example 1, 3 parts of graphite powder, 0.13 parts of kaolin, 0.3 parts of initiator, 1.4 parts of nucleating agent, 0.4 parts of plasticizer, and 5 parts of foaming agent; wherein the auxiliary dispersant is prepared by mixing equal masses of hydroxypropyl cellulose and hexadecyltrimethylammonium bromide, the initiator is tert-butyl perbenzoate, the nucleating agent is polyethylene wax, the plasticizer is prepared by mixing xylene and white oil in a weight ratio of 1:2, and the foaming agent is cyclopentane; A preparation method of expandable graphite polystyrene particles comprises the following steps: adding calcium phosphate and an auxiliary dispersant to deionized water, adding kaolin after mixing evenly, stirring for 25 minutes, adding graphite powder, continuing stirring for 25 minutes, then adding styrene, functional monomers, initiators, nucleating agents, and plasticizers, stirring evenly, raising the temperature to 91°C, reacting for 4.5 hours, finally adding a foaming agent and calcium carbonate, stirring evenly, continuing to raise the temperature to 128°C, continuing to react for 2.5 hours, naturally cooling to below 40°C, separating solid from liquid, taking solid, washing with water, and drying to constant weight to obtain expandable graphite polystyrene particles, wherein the average particle size of the particles is 0.76 mm; wherein the mass ratio of calcium carbonate to the foaming agent is 0.15:8.

[0022] Comparative Example 1: A kind of expandable graphite polystyrene particles, comprising the following components in parts by weight: 150 parts of deionized water, 0.5 parts of calcium phosphate, 0.2 parts of auxiliary dispersant, 100 parts of styrene, 5 parts of the functional monomer prepared in Example 1, 4 parts of graphite powder, 0.2 parts of kaolin, 0.6 parts of initiator, 2 parts of nucleating agent, 0.5 parts of plasticizer, and 5 parts of foaming agent; wherein the auxiliary dispersant is prepared by mixing equal masses of hydroxypropyl cellulose and hexadecyltrimethylammonium bromide, the initiator is azobisisobutyronitrile, the nucleating agent is polyethylene wax, the plasticizer is prepared by mixing xylene and white oil in a weight ratio of 1:2, and the foaming agent is n-pentane.

[0023] A method for preparing expandable graphite polystyrene particles is prepared according to the method described in Example 1.

[0024] Comparative Example 2: An expandable graphite polystyrene particle and a preparation method thereof are prepared according to the method described in Example 1, except that no functional monomer is added to the raw material components.

[0025] The expandable graphite polystyrene particles prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to relevant performance tests. For the heat resistance test, the samples were placed at 220°C for 5 days, and the high temperature deformation rate of the samples was observed. The test results were taken as absolute values. For the oxidation resistance test, the samples were placed in an accelerated aging test chamber with the temperature set at 70°C, the oxygen concentration at 50%, the humidity at 50%RH, and the time at 168h. The tensile strength reduction rate of the samples before and after the experiment was tested. For the UV resistance test, the samples were placed in an accelerated aging test chamber with the temperature set at 70°C, the oxygen concentration at 50%, the humidity at 50%RH, and the time at 168h. The tensile strength reduction rate of the samples before and after the experiment was tested. 4329-2005 plastic fluorescent ultraviolet exposure test standard, the test time is 500h; oxygen index test is carried out in accordance with GB / T2406.2-2009 "Determination of combustion behavior of plastics by oxygen index method Part 2: Room temperature test"; the expandable graphite polystyrene particles prepared in Examples 1-4 and Comparative Examples 1-2 are foamed, and after foaming, they are cooled and dried, the volumes of the samples before and after foaming are measured, and the foaming ratio is calculated, and the calculation formula is: foaming ratio = V2 / V1, where V1 is the volume of the sample before foaming, and V2 is the volume of the sample after foaming; chemical resistance is carried out in accordance with GB / T11547-2008 "Determination of plastic resistance to liquid chemical reagents", at (23±2)℃, the samples are placed in 99.5% acetic acid solution and 25% ammonium hydroxide solution for 192h, and the change rate of tensile strength of the samples is measured; the above tests are repeated three times and the average value is taken. The test results are shown in Table 1. It can be seen from the data in Table 1 that, compared with Comparative Examples 1-2, the expandable graphite polystyrene particles prepared in Examples 1-4 have excellent UV resistance, oxidation resistance, heat resistance, flame retardancy, and chemical resistance, while maintaining a good foaming ratio. It can be seen from the data in Example 1 and Comparative Example 1 that the comprehensive performance of polystyrene particles can be significantly improved by optimizing the weight fractions of raw materials such as styrene, functional monomers, and graphite powder; it can be seen from the data in Comparative Examples 1 and 2 that the functional monomers are prepared by a two-step method, and the polystyrene particles are prepared by compounding the functional monomers with raw materials such as styrene and graphite powder, and the UV resistance and oxidation resistance of the polystyrene particles are greatly improved.

[0026] Table 1 Test results of expandable graphite polystyrene particles related properties

[0027] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An expandable graphite polystyrene particle, characterized in that: The composition comprises the following components by weight: 120-150 parts of deionized water, 0.2-0.4 parts of calcium phosphate, 0.05-0.15 parts of auxiliary dispersant, 65-95 parts of styrene, 10-15 parts of functional monomer, 2-5 parts of graphite powder, 0.1-0.2 parts of kaolin, 0.2-0.5 parts of initiator, 1-2 parts of nucleating agent, 0.3-0.7 parts of plasticizer and 3-6 parts of foaming agent; The preparation method of the functional monomer is as follows: Step S1: 2-(3,4-difluorophenyl)ethylene oxide, 4-vinylphenylacetic acid, chromium acetate and toluene are uniformly mixed, and then the temperature is raised to 90-110° C. under stirring conditions, and the reaction is carried out for 6-8 hours. After cooling and purification, an intermediate is obtained; Step S2: 2-(1-benzotriazole)acetic acid, the intermediate, p-toluenesulfonic acid and N,N-dimethylformamide are uniformly mixed, the temperature is raised to 60-80° C. under stirring conditions, the reaction is performed for 5-7 hours, and after cooling and purification, a functional monomer is obtained.

2. The expandable graphite polystyrene particles according to claim 1, characterized in that: The molar ratio of 2-(3,4-difluorophenyl)ethylene oxide, 4-vinylphenylacetic acid and chromium acetate in step S1 is 1.4:1.3-1.5:0.02-0.

03.

3. The expandable graphite polystyrene particles according to claim 1, characterized in that: The mass volume ratio of 2-(3,4-difluorophenyl)ethylene oxide and toluene in step S1 is 0.1-0.3 g / mL.

4. The expandable graphite polystyrene particles according to claim 1, characterized in that: The molar ratio of 2-(1-benzotriazole)acetic acid, intermediate and p-toluenesulfonic acid in step S2 is 1.7:1.5-1.7:0.06-0.

10.

5. The expandable graphite polystyrene particles according to claim 1, characterized in that: The mass volume ratio of 2-(1-benzotriazole)acetic acid to N,N-dimethylformamide in step S2 is 0.2-0.4 g / mL.

6. The expandable graphite polystyrene particles according to claim 1, characterized in that: The initiator is one or more of azobisisobutyronitrile, dibenzoyl peroxide, diisopropylbenzene peroxide and tert-butyl perbenzoate.

7. The expandable graphite polystyrene particles according to claim 1, characterized in that: The auxiliary dispersant is prepared by mixing equal masses of hydroxypropyl cellulose and hexadecyl trimethyl ammonium bromide; and the nucleating agent is polyethylene wax.

8. The expandable graphite polystyrene particles according to claim 1, characterized in that: The plasticizer is prepared by mixing xylene and white oil.

9. The expandable graphite polystyrene particles according to claim 1, characterized in that: The foaming agent is n-pentane or cyclopentane.

10. The method for preparing expandable graphite polystyrene particles according to any one of claims 1 to 9, characterized in that: The following steps are involved: Add calcium phosphate and auxiliary dispersant to deionized water, mix well, then add kaolin, stir for 10-30 minutes, then add graphite powder, continue stirring for 10-30 minutes, then add styrene, functional monomer, initiator, nucleating agent, plasticizer, stir well, raise the temperature to 88-92°C, react for 4-6 hours, finally add foaming agent and calcium carbonate, stir well, raise the temperature to 125-130°C, continue to react for 2-4 hours, cool down, separate the solid and liquid, wash and dry the solid.

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