Heat-resistant and flame-retardant expandable polystyrene and preparation method thereof

Abstract

The present invention belongs to the technical field of polymer materials, and specifically relates to a heat-resistant and flame-retardant expandable polystyrene and a preparation method thereof. The present invention comprises the following components by weight: 150-200 parts of deionized water, 90-110 parts of styrene, 15-25 parts of modified styrene, 5-10 parts of foaming agent, 0.1-1.0 parts of dispersant, 0.4-0.7 parts of initiator, 1.5-2.5 parts of nucleating agent, 0.5-1.2 parts of plasticizer, and 3-6 parts of graphite powder; the present invention introduces modified styrene into the polystyrene molecular structure by chemical bonding, introduces phosphate, carbonate and amide groups into the polystyrene structure, significantly improves the flame retardancy, heat resistance and mechanical properties of the polymer material, and further improves the comprehensive performance of the composite material by compounding with components such as graphite powder and utilizing the synergistic effect of the composite system.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to heat-resistant and flame-retardant expandable polystyrene and a preparation method thereof. Background Art

[0002] Expandable polystyrene is a polymer material made by suspension polymerization of styrene monomer in a certain amount of pure water at a certain temperature after adding dispersant, emulsifier, initiator and foaming agent. Expandable polystyrene can be divided into three types: ordinary type, flame retardant type and graphite grade. Expandable polystyrene can be made into foam plastic products after pre-expansion, aging and molding. It has the advantages of light weight, low thermal conductivity, low water absorption, good sound insulation and shock absorption performance, simple molding process, etc. It is widely used in building exterior wall insulation, electrical instruments, electronic product cushioning packaging, food packaging, etc.

[0003] In recent years, with the continuous improvement of fire safety requirements in various industries, flame-retardant expandable polystyrene has received more and more attention. At present, it has been widely involved in many key industries such as construction, electrical and packaging. In the aspect of building exterior wall insulation, it is an important thermal insulation material to help achieve the goal of building energy conservation; in the field of buffer packaging of electrical instruments and electronic products, it provides protection for precision equipment and buffers external force impact; in terms of food packaging, while ensuring a certain preservation performance, it also takes into account the physical protection of the product. From the perspective of advantages, it inherits the lightweight characteristics of expandable polystyrene, greatly reduces the weight of the applied products, and facilitates transportation and installation. For example, in the construction of exterior wall insulation of high-rise buildings, it effectively reduces the wall load and reduces safety risks. Its low thermal conductivity and excellent thermal insulation performance can effectively maintain the stability of the ambient temperature and reduce energy consumption. The advantage of low water absorption enables the material to maintain good performance in a humid environment. For example, the packaging of outdoor electrical equipment is not easily damaged by moisture even in rainy weather. Good sound insulation and shock absorption performance can protect fragile products such as electronic products and avoid vibration and collision damage during transportation. The molding process is simple, which greatly reduces production costs, improves production efficiency, and is conducive to large-scale industrial production.

[0004] However, the existing flame-retardant expandable polystyrene also has some outstanding problems. In terms of flame retardant systems, the flame retardant purpose is currently mainly achieved by adding flame retardants, but flame retardants are mostly small molecules, which have poor compatibility with the polystyrene matrix and are very easy to precipitate during the processing, use and storage of the material. Once precipitated, it will not only destroy the original physical structure uniformity of the material, but also form weak points on the surface of the material, allowing external flames to easily break through, which will seriously affect the flame retardant properties of expandable polystyrene products, and cannot provide a reliable and lasting fire barrier for the product, and it is difficult to meet the needs of places with high fire protection requirements. In addition, the heat resistance of expandable polystyrene itself also needs to be improved. In high temperature environments, the material is prone to softening and deformation, which not only weakens its structural stability, but also may cause displacement and damage to adjacent components, especially in application scenarios such as electrical equipment packaging and industrial pipeline insulation near heat sources. Once the temperature exceeds the tolerance range of the material, it will cause a series of safety hazards and threaten the normal operation of the entire system. Summary of the invention

[0005] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a heat-resistant and flame-retardant expandable polystyrene and a preparation method thereof, wherein modified styrene is prepared by a three-step chemical reaction, and is used as a functional monomer and grafted into the polystyrene molecular structure by chemical bonding, which can ensure the long-term and stability of the flame retardant properties of the polymer material. At the same time, the polystyrene molecular chain is modified by introducing a heat-resistant functional group, which enhances the interaction between the molecular chains and can also improve the heat resistance of the polymer material. The present invention uses the synergistic effect of the composite system to construct a new expandable polystyrene material with excellent flame retardant, heat-resistant and mechanical properties, broadens its application breadth and depth, and meets the growing demand for high-performance materials in various industries.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: A heat-resistant and flame-retardant expandable polystyrene comprises the following components, measured by weight: 150-200 parts of deionized water, 90-110 parts of styrene, 15-25 parts of modified styrene, 5-10 parts of foaming agent, 0.1-1.0 parts of dispersant, 0.4-0.7 parts of initiator, 1.5-2.5 parts of nucleating agent, 0.5-1.2 parts of plasticizer, and 3-6 parts of graphite powder; The preparation method of the modified styrene is as follows: S1. In a nitrogen atmosphere and under stirring conditions, methyl 4-hydroxybutyrate is dispersed in N,N-dimethylformamide, the temperature is raised to 80-90°C, di-n-propyl chlorophosphate is added dropwise, the addition is completed within 1-3 hours, the reaction is continued for 2-4 hours, and intermediate 1 is obtained after purification; S2. Under stirring conditions, disperse the intermediate 1 obtained in step S1 and ethanolamine in anhydrous ethanol, add sodium methoxide methanol solution dropwise within 30-50 minutes, then raise the temperature to 50-60° C., react for 5-6 hours, and purify to obtain intermediate 2; S3, under stirring conditions, dispersing the intermediate 2 obtained in step S2 in N,N-dimethylformamide, adding p-toluenesulfonic acid and 4-vinylphenylacetic acid in sequence, raising the temperature to 60-70° C., reacting for 5-6 hours, and obtaining modified styrene after purification; The synthetic route of modified styrene is as follows: ; ; .

[0007] The invention uses methyl 4-hydroxybutyrate and di-n-propyl chlorophosphate as starting materials, performs an esterification reaction under heating conditions, and obtains an intermediate 1; then uses the intermediate 1 and ethanolamine as raw materials, and obtains an intermediate 2 under the action of sodium methoxide; finally uses the intermediate 2 and 4-vinylphenylacetic acid as raw materials, and obtains modified styrene under the action of p-toluenesulfonic acid.

[0008] In order to obtain modified styrene and ensure product consistency, the molar ratio of methyl 4-hydroxybutyrate and di-n-propyl chlorophosphate in step S1 is 1:1.0-1.2, and the mass volume ratio of methyl 4-hydroxybutyrate and N,N-dimethylformamide is 0.1-0.3 g / mL; the mass ratio of intermediate 1 and ethanolamine in step S2 is 10:4-5, the mass volume ratio of intermediate 1 and anhydrous ethanol is 0.13-0.21 g / mL, the volume ratio of anhydrous ethanol and sodium methoxide methanol solution is 50:8-10, and the molar concentration of sodium methoxide methanol solution is 4-5 mol / L; the molar ratio of intermediate 2, p-toluenesulfonic acid and 4-vinylphenylacetic acid in step S3 is 1:0.04-0.06:1.0-1.2, and the amount of intermediate 2 added to N,N-dimethylformamide is 0.22-0.28 g / mL.

[0009] Furthermore, the foaming agent is one or more of n-pentane, isopentane, and neopentane; the nucleating agent is polyethylene wax; the dispersant is one or more of sodium dodecylbenzene sulfonate, tricalcium phosphate, anhydrous sodium sulfate, and hydroxyethyl cellulose; the initiator is one or more of diisopropylbenzene peroxide, tert-butyl perbenzoate, and tert-butyl peroxy-2-ethylhexanoate; and the plasticizer is prepared by mixing white oil and dioctyl phthalate, and the mass ratio of white oil to dioctyl phthalate is 2.5-3.5:1.

[0010] The present invention also provides a method for preparing heat-resistant and flame-retardant expandable polystyrene, comprising the following steps: after deionized water and a dispersant are mixed evenly, styrene, modified styrene, graphite powder, an initiator, a plasticizer, and a nucleating agent are added in sequence, the temperature is raised to 87-93°C after mixing evenly, and the mixture is stirred for reaction for 4-6 hours, and then calcium carbonate and a foaming agent are added, the temperature is further raised to 120-130°C after mixing evenly, the mixture is stirred for reaction for 2-4 hours, and the material is discharged after cooling to obtain the polystyrene; wherein the mass ratio of the calcium carbonate to the foaming agent is 0.1-0.3:8.

[0011] The present invention has the following beneficial effects: The present invention introduces modified styrene as a functional monomer into the polystyrene molecular structure, and introduces phosphate, carbonate and amide groups into the polystyrene structure. In terms of heat resistance, by introducing heat-resistant functional groups such as carbonate and amide groups into the polystyrene molecular chain, the interaction between molecular chains is enhanced, the movement of molecular chains is restricted, and the rigidity of molecular chains is improved, thereby effectively improving the thermal stability and heat resistance of polymer materials, so that polymer materials can better maintain their shape and performance under high temperature environments, and reduce deformation or performance degradation caused by heat. In terms of flame retardant properties, phosphate and amide groups are introduced into the polystyrene structure, and amide groups and phosphates can form a stable carbon layer through carbonization in the condensed phase, preventing heat, oxygen transfer and combustible gas from escaping, while changing the thermal decomposition pathway of the material and reducing the thermal decomposition rate at a lower temperature; in the gas phase, phosphates can be decomposed to produce non-combustible gases to dilute the concentration of combustible gases, and amide groups can also be decomposed to produce nitrogen for further dilution, and the components in phosphates and amide groups can also capture free radicals generated by combustion, interrupt the combustion chain reaction, significantly improve the flame retardant properties of polymer materials, and ensure their long-term effectiveness and stability. In terms of mechanical properties, phosphate, carbonate and amide groups are introduced into the polystyrene structure. The phosphorus-oxygen double bond in phosphate and the carbonyl group in carbonate have strong polarity, which enhances the interaction between molecular chains. When stretched by external force, the molecular chains are not prone to relative slippage, thereby improving the mechanical properties of the polymer material. The rigid structure of the amide group limits the bending and twisting of the molecular chain, so that stress can be more effectively transmitted between molecular chains, further enhancing the bearing capacity of the material. The present invention also adds components such as graphite powder, and utilizes the synergistic effect of the composite system to further improve the flame retardant properties, heat resistance and mechanical properties of the composite material.

[0012] The present invention successfully achieves full reaction and uniform dispersion of the components in the composite material by reasonably selecting the components and controlling the reaction conditions, thereby ensuring the overall performance of the composite material. 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] White oil, model No. 5, specific gravity 0.86, flash point 140℃, brand Shengda Chemical; graphite powder, mesh number 325 mesh, density 2.35g / cm³, fixed carbon 99.7%, brand Yongshun; hydroxyethyl cellulose, density 0.75g / mL at 25℃g / mL, pH value pH (20g / L, 25℃): 5.0-8.0, brand Nengju Chemical; polyethylene wax, model Q-18PE wax, effective ingredient content 99%, brand Xindongyi. The raw materials used in the following examples are all common commercially available products.

[0015] Embodiment 1: A heat-resistant and flame-retardant expandable polystyrene comprises the following components in parts by weight: 170 parts of deionized water, 100 parts of styrene, 20 parts of modified styrene, 8 parts of foaming agent, 0.5 parts of dispersant, 0.6 parts of initiator, 2 parts of nucleating agent, 0.9 parts of plasticizer, and 4 parts of graphite powder; the foaming agent is n-pentane; the dispersant is prepared by mixing sodium dodecylbenzene sulfonate and hydroxyethyl cellulose, and the mass ratio of sodium dodecylbenzene sulfonate to hydroxyethyl cellulose is 1:4; the initiator is prepared by mixing diisopropyl peroxide and tert-butyl perbenzoate of equal mass; the nucleating agent is polyethylene wax; the plasticizer is prepared by mixing white oil and dioctyl phthalate, and the mass ratio of white oil to dioctyl phthalate is 3:1; The preparation method of the modified styrene is: S1. In a nitrogen atmosphere and under stirring conditions, methyl 4-hydroxybutyrate is dispersed in N,N-dimethylformamide, the temperature is raised to 85°C, di-n-propyl chlorophosphate is added dropwise, the addition is completed within 2 hours, the reaction is continued for 3 hours, and the mixture is naturally cooled to room temperature. Deionized water and ethyl acetate are then added for extraction, and the ester phase is subjected to reduced pressure distillation and vacuum drying to obtain intermediate 1; wherein the molar ratio of methyl 4-hydroxybutyrate to di-n-propyl chlorophosphate is 1:1.1, the mass volume ratio of methyl 4-hydroxybutyrate to N,N-dimethylformamide is 0.2 g / mL, and the volume ratio of N,N-dimethylformamide to deionized water and ethyl acetate is 1:1:2; S2. Under stirring conditions, disperse the intermediate 1 obtained in step S1 and ethanolamine in anhydrous ethanol, add sodium methoxide methanol solution dropwise, and complete the addition within 40 minutes, then raise the temperature to 55°C, reflux for 5.5 hours, cool naturally to room temperature, and obtain intermediate 2 by vacuum distillation and vacuum drying; wherein the mass ratio of intermediate 1 to ethanolamine is 10:4.5, the mass volume ratio of intermediate 1 to anhydrous ethanol is 0.17 g / mL, the volume ratio of anhydrous ethanol to sodium methoxide methanol solution is 50:9, and the molar concentration of the sodium methoxide methanol solution is 4.5 mol / L; S3. Under stirring conditions, the intermediate 2 obtained in step S2 is dispersed in N,N-dimethylformamide, p-toluenesulfonic acid and 4-vinylphenylacetic acid are added in sequence, the temperature is raised to 65°C, the reaction is carried out for 5.5 hours, and the mixture is naturally cooled to room temperature. Deionized water and sodium bicarbonate are added in sequence, the reaction is carried out for 30 minutes, and then ethyl acetate is added for extraction. The organic phase is taken and distilled under reduced pressure and dried in vacuo to obtain modified styrene; wherein the molar ratio of intermediate 2, p-toluenesulfonic acid and 4-vinylphenylacetic acid is 1:0.05:1.1, the amount of intermediate 2 added to N,N-dimethylformamide is 0.25 g / mL, and the mass ratio of p-toluenesulfonic acid, deionized water and sodium bicarbonate is 5:40:4; The NMR results of modified styrene are: 1 H NMR (300MHz, DMSO-d6) δ 8.01 (s, 1H), 7.64 (d, 2H), 7.37 (d, 2H), 6.72 (t, 1H), 5.76 (d, 1H), 5.25 (d, 1H), 4.07-4.12 (m, 8 H), 3.71 (s, 2H), 3.28 (t, 2H), 2.34 (t, 2H), 2.01-2.04 (m, 2H), 1.62-1.65 (m, 4H), 0.90 (t, 6H).

[0016] A preparation method of heat-resistant flame-retardant expandable polystyrene comprises the following steps: after deionized water and a dispersant are mixed evenly, styrene, modified styrene, graphite powder, an initiator, a plasticizer and a nucleating agent are added in sequence, the temperature is raised to 90°C after the mixture is mixed evenly, the mixture is stirred and reacted for 5 hours, calcium carbonate and a foaming agent are added, the temperature is further raised to 125°C after the mixture is mixed evenly, the mixture is stirred and reacted for 3 hours, the mixture is naturally cooled to 40-50°C, and the material is discharged to obtain the polystyrene; wherein the mass ratio of the calcium carbonate to the foaming agent is 0.2:8.

[0017] Embodiment 2: A heat-resistant and flame-retardant expandable polystyrene comprises the following components in parts by weight: 150 parts of deionized water, 90 parts of styrene, 25 parts of modified styrene, 10 parts of foaming agent, 1 part of dispersant, 0.4 parts of initiator, 1.5 parts of nucleating agent, 0.5 parts of plasticizer, and 6 parts of graphite powder; the foaming agent is isopentane; the dispersant is prepared by mixing sodium dodecylbenzene sulfonate and anhydrous sodium sulfate, and the mass ratio of sodium dodecylbenzene sulfonate to anhydrous sodium sulfate is 1:2; the initiator is prepared by mixing equal masses of diisopropyl peroxide and tert-butyl perbenzoate; the nucleating agent is polyethylene wax; the plasticizer is prepared by mixing white oil and dioctyl phthalate, and the mass ratio of white oil to dioctyl phthalate is 3.5:1; The preparation method of the modified styrene is: S1. In a nitrogen atmosphere and under stirring conditions, methyl 4-hydroxybutyrate is dispersed in N,N-dimethylformamide, the temperature is raised to 80°C, di-n-propyl chlorophosphate is added dropwise, the addition is completed within 3 hours, the reaction is continued for 4 hours, and the mixture is naturally cooled to room temperature. Deionized water and ethyl acetate are then added for extraction, and the ester phase is subjected to reduced pressure distillation and vacuum drying to obtain intermediate 1; wherein the molar ratio of methyl 4-hydroxybutyrate to di-n-propyl chlorophosphate is 1:1, the mass volume ratio of methyl 4-hydroxybutyrate to N,N-dimethylformamide is 0.1 g / mL, and the volume ratio of N,N-dimethylformamide to deionized water and ethyl acetate is 1:1:2; S2. Under stirring conditions, disperse the intermediate 1 obtained in step S1 and ethanolamine in anhydrous ethanol, add sodium methoxide methanol solution dropwise, and complete the addition within 50 minutes, then raise the temperature to 50°C, reflux for 6 hours, naturally cool to room temperature, and obtain intermediate 2 after reduced pressure distillation and vacuum drying; wherein the mass ratio of intermediate 1 to ethanolamine is 10:4, the mass volume ratio of intermediate 1 to anhydrous ethanol is 0.13 g / mL, the volume ratio of anhydrous ethanol to sodium methoxide methanol solution is 50:8, and the molar concentration of the sodium methoxide methanol solution is 4 mol / L; S3. Under stirring conditions, disperse the intermediate 2 obtained in step S2 in N,N-dimethylformamide, add p-toluenesulfonic acid and 4-vinylphenylacetic acid in sequence, raise the temperature to 60°C, react for 6 hours, cool naturally to room temperature, then add deionized water and sodium bicarbonate in sequence, react for 30 minutes, then add ethyl acetate for extraction, take the organic phase and distill under reduced pressure, and vacuum dry to obtain modified styrene; wherein the molar ratio of intermediate 2, p-toluenesulfonic acid, and 4-vinylphenylacetic acid is 1:0.04:1, the amount of intermediate 2 added to N,N-dimethylformamide is 0.22 g / mL, and the mass ratio of p-toluenesulfonic acid, deionized water, and sodium bicarbonate is 5:40:4.

[0018] A method for preparing heat-resistant and flame-retardant expandable polystyrene comprises the following steps: after deionized water and a dispersant are mixed evenly, styrene, modified styrene, graphite powder, an initiator, a plasticizer and a nucleating agent are added in sequence, the temperature is raised to 87°C after the mixture is mixed evenly, and the mixture is stirred for reaction for 6 hours, and then calcium carbonate and a foaming agent are added, the temperature is further raised to 120°C after the mixture is mixed evenly, and the mixture is stirred for reaction for 2 hours, and the mixture is naturally cooled to 40-50°C and then the material is discharged to obtain the polystyrene; wherein the mass ratio of the calcium carbonate to the foaming agent is 0.1:8.

[0019] Embodiment 3: A heat-resistant and flame-retardant expandable polystyrene comprises the following components in parts by weight: 200 parts of deionized water, 110 parts of styrene, 15 parts of modified styrene, 5 parts of foaming agent, 0.1 parts of dispersant, 0.7 parts of initiator, 2.5 parts of nucleating agent, 1.2 parts of plasticizer, and 3 parts of graphite powder; the foaming agent is neopentane; the dispersant is prepared by mixing sodium dodecylbenzene sulfonate and tricalcium phosphate, and the mass ratio of sodium dodecylbenzene sulfonate to tricalcium phosphate is 1:2.5; the initiator is prepared by mixing equal masses of diisopropylbenzene peroxide and tert-butyl peroxide-2-ethylhexanoate; the nucleating agent is polyethylene wax; the plasticizer is prepared by mixing white oil and dioctyl phthalate, and the mass ratio of white oil to dioctyl phthalate is 2.5:1; The preparation method of the modified styrene is: S1. In a nitrogen atmosphere and under stirring conditions, methyl 4-hydroxybutyrate is dispersed in N,N-dimethylformamide, the temperature is raised to 90°C, di-n-propyl chlorophosphate is added dropwise, the addition is completed within 1 hour, the reaction is continued for 2 hours, and the mixture is naturally cooled to room temperature. Deionized water and ethyl acetate are then added for extraction, and the ester phase is subjected to reduced pressure distillation and vacuum drying to obtain intermediate 1; wherein the molar ratio of methyl 4-hydroxybutyrate to di-n-propyl chlorophosphate is 1:1.2, the mass volume ratio of methyl 4-hydroxybutyrate to N,N-dimethylformamide is 0.3 g / mL, and the volume ratio of N,N-dimethylformamide to deionized water and ethyl acetate is 1:1:2; S2. Under stirring conditions, disperse the intermediate 1 obtained in step S1 and ethanolamine in anhydrous ethanol, add sodium methoxide methanol solution dropwise, and complete the addition within 30 minutes, then raise the temperature to 60°C, reflux for 5 hours, naturally cool to room temperature, and obtain intermediate 2 after reduced pressure distillation and vacuum drying; wherein the mass ratio of intermediate 1 to ethanolamine is 10:5, the mass volume ratio of intermediate 1 to anhydrous ethanol is 0.21 g / mL, the volume ratio of anhydrous ethanol to sodium methoxide methanol solution is 50:10, and the molar concentration of the sodium methoxide methanol solution is 5 mol / L; S3. Under stirring conditions, the intermediate 2 obtained in step S2 is dispersed in N,N-dimethylformamide, p-toluenesulfonic acid and 4-vinylphenylacetic acid are added in sequence, the temperature is raised to 70°C, the reaction is carried out for 5 hours, and the mixture is naturally cooled to room temperature. Deionized water and sodium bicarbonate are added in sequence, the reaction is carried out for 30 minutes, and then ethyl acetate is added for extraction. The organic phase is taken and distilled under reduced pressure and dried in vacuo to obtain modified styrene; wherein the molar ratio of intermediate 2, p-toluenesulfonic acid and 4-vinylphenylacetic acid is 1:0.06:1.2, the amount of intermediate 2 added to N,N-dimethylformamide is 0.28 g / mL, and the mass ratio of p-toluenesulfonic acid, deionized water and sodium bicarbonate is 5:40:4.

[0020] A preparation method of heat-resistant flame-retardant expandable polystyrene comprises the following steps: after deionized water and a dispersant are mixed evenly, styrene, modified styrene, graphite powder, an initiator, a plasticizer and a nucleating agent are added in sequence, the temperature is raised to 93°C after the mixture is mixed evenly, the mixture is stirred and reacted for 4 hours, calcium carbonate and a foaming agent are added, the temperature is further raised to 130°C after the mixture is mixed evenly, the mixture is stirred and reacted for 2 hours, the mixture is naturally cooled to 40-50°C, and the material is discharged to obtain the polystyrene; wherein the mass ratio of the calcium carbonate to the foaming agent is 0.3:8.

[0021] Embodiment 4: A heat-resistant and flame-retardant expandable polystyrene comprises the following components, in parts by weight: 180 parts of deionized water, 105 parts of styrene, 22 parts of modified styrene, 7 parts of foaming agent, 0.6 parts of dispersant, 0.5 parts of initiator, 2.1 parts of nucleating agent, 0.8 parts of plasticizer, and 5 parts of graphite powder; the foaming agent is n-pentane; the dispersant is prepared by mixing sodium dodecylbenzene sulfonate and hydroxyethyl cellulose, and the mass ratio of sodium dodecylbenzene sulfonate to hydroxyethyl cellulose is 1:4; the initiator is prepared by mixing equal masses of diisopropyl peroxide and tert-butyl perbenzoate; the nucleating agent is polyethylene wax; the plasticizer is prepared by mixing white oil and dioctyl phthalate, and the mass ratio of white oil to dioctyl phthalate is 3:1.

[0022] A method for preparing heat-resistant and flame-retardant expandable polystyrene comprises the following steps: after deionized water and a dispersant are mixed evenly, styrene, modified styrene, graphite powder, an initiator, a plasticizer and a nucleating agent are added in sequence, the temperature is raised to 90°C after the mixture is mixed evenly, the mixture is stirred and reacted for 4 hours, calcium carbonate and a foaming agent are added, the temperature is further raised to 125°C after the mixture is mixed evenly, the mixture is stirred and reacted for 4 hours, the mixture is naturally cooled to 40-50°C, and the material is discharged to obtain the polystyrene; wherein the mass ratio of the calcium carbonate to the foaming agent is 0.2:8.

[0023] Comparative Example 1: A heat-resistant and flame-retardant expandable polystyrene comprises the following components, in parts by weight: 130 parts of deionized water, 80 parts of styrene, 7 parts of modified styrene prepared in Example 1, 5 parts of foaming agent, 0.5 parts of dispersant, 0.4 parts of initiator, 1.7 parts of nucleating agent, 0.8 parts of plasticizer, and 3 parts of graphite powder; the foaming agent is n-pentane; the dispersant is prepared by mixing sodium dodecylbenzene sulfonate and hydroxyethyl cellulose, and the mass ratio of sodium dodecylbenzene sulfonate to hydroxyethyl cellulose is 1:4; the initiator is prepared by mixing equal masses of diisopropyl peroxide and tert-butyl perbenzoate; the nucleating agent is polyethylene wax; the plasticizer is prepared by mixing white oil and dioctyl phthalate, and the mass ratio of white oil to dioctyl phthalate is 3:1.

[0024] A method for preparing heat-resistant and flame-retardant expandable polystyrene is prepared according to the method described in Example 1.

[0025] Comparative Example 2: A heat-resistant and flame-retardant expandable polystyrene and a preparation method thereof are prepared according to the method described in Example 1, except that: no modified styrene is added to the raw material components.

[0026] In accordance with the provisions of GB / T6594.2-2003 "Plastic polystyrene (PS) molding and extrusion materials Part 2: Sample preparation and performance determination", relevant performance tests were carried out on the heat-resistant and flame-retardant expandable polystyrene compression-molded test pieces prepared in Examples 1-4 and Comparative Examples 1-2. The combustion performance test was carried out according to the UL-94 vertical combustion test standard. The length of the sample was 125 mm, the width was 13 mm, and the thickness was 11 mm. The oxygen index test was carried out according to GB / T2406.2-2009 "Determination of Combustion Behavior of Plastics by Oxygen Index Method Part 2: Room Temperature Test"; the expandable polystyrene prepared in Examples 1-4 and Comparative Examples 1-2 was foamed. After the foaming was completed, the volume of the sample before and after foaming was measured after cooling and drying, and the foaming ratio was calculated. The calculation formula was: foaming ratio = V2 / V1, where V1 is the volume of the sample before foaming, and V2 is the volume of the sample after foaming; heat resistance test: a sample with a size of 120 mm × 10 mm × 10 mm was placed at 250 ° C for 96 h, and naturally cooled to room temperature after the test, and the change in the size of the sample before and after the test was recorded; the tensile strength at break test was carried out according to ASTM-D3575 Test method for flexible porous materials made of olefin polymers; the above tests were repeated three times and the average value was taken. The test results are shown in Table 1. From the data in Table 1, it can be seen that compared with Comparative Examples 1-2, the heat-resistant flame-retardant expandable polystyrene prepared in Examples 1-4 maintains a good foaming ratio, and also has excellent flame retardancy, tensile strength at break, and heat resistance. The combustion grade of the heat-resistant flame-retardant expandable polystyrene prepared in Examples 1-4 is V0, the oxygen index is above 36.1%, and after being placed at 250°C for 96 hours, the sample size change is less than 0.44 mm 3 , showing excellent comprehensive performance.

[0027] Table 1 Test results of relevant properties of heat-resistant and flame-retardant expandable polystyrene:

[0028] 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. A heat-resistant and flame-retardant expandable polystyrene, characterized in that: The composition comprises the following components by weight: 150-200 parts of deionized water, 90-110 parts of styrene, 15-25 parts of modified styrene, 5-10 parts of foaming agent, 0.1-1.0 parts of dispersant, 0.4-0.7 parts of initiator, 1.5-2.5 parts of nucleating agent, 0.5-1.2 parts of plasticizer, and 3-6 parts of graphite powder; The preparation method of the modified styrene is as follows: S1. In a nitrogen atmosphere and under stirring conditions, methyl 4-hydroxybutyrate is dispersed in N,N-dimethylformamide, the temperature is raised to 80-90°C, di-n-propyl chlorophosphate is added dropwise, the addition is completed within 1-3 hours, the reaction is continued for 2-4 hours, and intermediate 1 is obtained after purification; S2. Under stirring conditions, disperse the intermediate 1 obtained in step S1 and ethanolamine in anhydrous ethanol, add sodium methoxide methanol solution dropwise within 30-50 minutes, then raise the temperature to 50-60° C., react for 5-6 hours, and purify to obtain intermediate 2; S3. Under stirring conditions, disperse the intermediate 2 obtained in step S2 in N,N-dimethylformamide, add p-toluenesulfonic acid and 4-vinylphenylacetic acid in sequence, raise the temperature to 60-70° C., react for 5-6 hours, and obtain modified styrene after purification.

2. The heat-resistant and flame-retardant expandable polystyrene according to claim 1, characterized in that: The molar ratio of methyl 4-hydroxybutyrate to di-n-propyl chlorophosphate in step S1 is 1:1.0-1.2, and the mass volume ratio of methyl 4-hydroxybutyrate to N,N-dimethylformamide is 0.1-0.3 g / mL.

3. The heat-resistant and flame-retardant expandable polystyrene according to claim 1, characterized in that: In step S2, the mass ratio of the intermediate 1 to ethanolamine is 10:4-5, the mass volume ratio of the intermediate 1 to anhydrous ethanol is 0.13-0.21 g / mL, the volume ratio of anhydrous ethanol to sodium methoxide methanol solution is 50:8-10, and the molar concentration of the sodium methoxide methanol solution is 4-5 mol / L.

4. The heat-resistant and flame-retardant expandable polystyrene according to claim 1, characterized in that: The molar ratio of the intermediate 2, p-toluenesulfonic acid and 4-vinylphenylacetic acid in step S3 is 1:0.04-0.06:1.0-1.2, and the amount of the intermediate 2 added to the N,N-dimethylformamide is 0.22-0.28 g / mL.

5. The heat-resistant and flame-retardant expandable polystyrene according to claim 1, characterized in that: The foaming agent is one or more of n-pentane, isopentane and neopentane; the nucleating agent is polyethylene wax.

6. The heat-resistant and flame-retardant expandable polystyrene according to claim 1, characterized in that: The dispersant is one or more of sodium dodecylbenzene sulfonate, tricalcium phosphate, anhydrous sodium sulfate and hydroxyethyl cellulose.

7. The heat-resistant and flame-retardant expandable polystyrene according to claim 1, characterized in that: The initiator is one or more of dicumyl peroxide, tert-butyl perbenzoate, and tert-butyl peroxy-2-ethylhexanoate.

8. The heat-resistant and flame-retardant expandable polystyrene according to claim 1, characterized in that: The plasticizer is prepared by mixing white oil and dioctyl phthalate, and the mass ratio of the white oil to the dioctyl phthalate is 2.5-3.5:

1.

9. The method for preparing heat-resistant flame-retardant expandable polystyrene according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: after deionized water and a dispersant are mixed evenly, styrene, modified styrene, graphite powder, an initiator, a plasticizer and a nucleating agent are added in sequence, the temperature is raised to 87-93°C after the mixture is evenly mixed, the mixture is stirred and reacted for 4-6 hours, calcium carbonate and a foaming agent are added, the temperature is further raised to 120-130°C after the mixture is evenly mixed, the mixture is stirred and reacted for 2-4 hours, the mixture is discharged after the mixture is cooled, and the product is obtained.

10. The method for preparing heat-resistant and flame-retardant expandable polystyrene according to claim 9, characterized in that: The mass ratio of the calcium carbonate to the foaming agent is 0.1-0.3:8.

Images