A modified expandable polystyrene and preparation method thereof

Abstract

The invention relates to the technical field of polystyrene, and specifically discloses a modified expandable polystyrene and a preparation method thereof. The modified expandable polystyrene comprises the following raw materials in parts by weight: 110-120 parts of deionized water, 80-90 parts of styrene, 0.03-0.7 parts of calcium carbonate, 0.5-0.6 parts of a modified dispersant, 0.1-0.3 parts of an auxiliary dispersant, 0.3-0.5 parts of an initiator, and 3-4 parts of a foaming agent. The modified dispersant contains phosphorus, fluorine and bromine elements in its molecular structure, and the elements cooperate and act synergistically with each other to improve the flame retardant property, thermal insulation property and mechanical property of the modified expandable polystyrene. Therefore, the modified expandable polystyrene prepared by the invention can be widely used in the fields of construction, packaging, equipment, device and decoration.

Description

Technical Field

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

[0002] Expandable polystyrene (EPS for short) is a polymer material made by mixing styrene monomer with a certain amount of pure water and adding dispersants, emulsifiers, initiators and foaming agents for suspension polymerization at a specific temperature. This material has excellent thermal insulation properties, sound absorption effects, compressive strength and light weight, and is widely used in construction, packaging, equipment and decoration.

[0003] The Chinese patent application number 202410210591.9 discloses an expandable polystyrene containing graphite carbon black composite particles and a preparation method thereof. The expandable polystyrene is composed of styrene, a nucleating agent, an organic peroxide compound, desalted water, polyvinyl alcohol, a suspending agent, sodium pyrophosphate, hydroxyethyl cellulose, composite particles, sodium bisulfite and pentane, and the composite particles include nanographite and nanocarbon black. After the raw materials are evenly mixed, the nanoparticles are well dispersed in the matrix and merged with the oil-based components to finally obtain excellent flame retardant, thermal insulation and mechanical properties. However, the graphite used in the invention has low surface energy and is difficult to disperse in the polystyrene matrix. If the dispersion is insufficient, the comprehensive performance of the expandable polystyrene will be affected. The Chinese patent application number 201910489465.0 discloses a method for preparing an ultra-low thermal conductivity expandable polystyrene resin using sericite, which is synthesized by incorporating sericite into styrene monomers before suspension polymerization. The thermal conductivity of the prepared foam product reaches 0.0297 W / (m·K), which is lower than all existing expandable polystyrene foam products, effectively reducing the amount of polystyrene foam insulation materials used. In addition, the preparation method of the present invention is low-cost and simple in process, and can be produced under existing equipment and processes. However, in certain specific application scenarios, the flame retardant properties of the expandable polystyrene in high temperature environments may be insufficient, such as in electronic equipment or building materials, and this insufficient performance will limit its safety and scope of application under these high temperature conditions.

[0004] Therefore, there is an urgent need to develop a modified expandable polystyrene that excels in flame retardancy, heat resistance and mechanical properties in order to better meet the application needs in various fields. Summary of the invention

[0005] The purpose of the present invention is to provide a modified expandable polystyrene and a preparation method thereof in view of the deficiencies of the prior art, and to prepare the modified expandable polystyrene with excellent performance by a chemical modification method, thereby expanding its application range.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: A modified expandable polystyrene comprises the following raw materials in parts by weight: 110-120 parts of deionized water, 80-90 parts of styrene, 0.03-0.7 parts of calcium carbonate, 0.5-0.6 parts of a modified dispersant, 0.1-0.3 parts of an auxiliary dispersant, 0.3-0.5 parts of an initiator, and 3-4 parts of a foaming agent; the preparation method of the modified dispersant is as follows: Step S1, adding o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine to N,N-dimethylformamide at 100-110° C. with stirring, reacting for 3-4 hours, cooling to room temperature, and removing the solvent to obtain an intermediate; Step S2, uniformly mixing the intermediate obtained in step S1, 2-bromo-3-fluoropyridine-6-carboxylic acid and sodium ethoxide, reacting at 90-100° C. with stirring for 4-5 hours, cooling to room temperature, and purifying to obtain a modifier; The synthetic route of the modifier is as follows: ; ; Step S3, adding the dispersant and the modifier obtained in step S2 to N,N-dimethylformamide at 40-60° C. with stirring, reacting for 60-90 minutes, cooling to room temperature, and purifying to obtain a modified dispersant.

[0007] Furthermore, in step S1, the molar ratio of o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine is 1:1-1.1:0.02-0.03, and the amount of o-aminobenzaldehyde added to N,N-dimethylformamide is 0.09-0.18 g / mL.

[0008] Furthermore, in step S2, the molar ratio of the intermediate, 2-bromo-3-fluoropyridine-6-carboxylic acid, and sodium ethoxide is 1:0.8-0.9:0.002-0.004.

[0009] Furthermore, in step S3, the molar ratio of the dispersant to the modifier is 1:0.09-0.1, and the amount of the modifier added to N,N-dimethylformamide is 0.09-0.13 g / mL.

[0010] Furthermore, the dispersant in step S3 is one or more of cellulose acetate, hydroxyethyl cellulose, methyl cellulose, and ethyl cellulose.

[0011] Furthermore, the auxiliary dispersant is one or more of sodium dodecylbenzene sulfonate, calcium phosphate, stearic acid, fatty alcohol polyoxyethylene ether, and polyvinyl alcohol.

[0012] Furthermore, the initiator is one or more of dicumyl peroxide, tert-butyl perbenzoate, tert-butyl peroxy-2-ethylhexanoate, dibenzoyl peroxide, and azobisisobutyronitrile.

[0013] Furthermore, the foaming agent is one or more of n-pentane, isopentane, petroleum ether and butane.

[0014] The present invention also provides a method for preparing modified expandable polystyrene, comprising the following steps: (1) Add deionized water, styrene, modified dispersant, auxiliary dispersant and initiator into a reactor, mix well and heat to 90-95°C, react for 2-3.5 hours, then add calcium carbonate and continue to react for 30-40 minutes to obtain polystyrene particles; (2) Add a blowing agent to the polystyrene particles obtained in step (1), then heat the mixture to 108-112°C, react for 1.5-2h, then heat the mixture to 119-121°C, continue to react for 3-4h, then cool the mixture to 50-55°C, wash, dry, and discharge the mixture to obtain modified expandable polystyrene.

[0015] The present invention has the following beneficial effects: The present invention adopts a chemical modification method to prepare a modified dispersant, and then adjusts the ratio with raw materials such as styrene and calcium carbonate to obtain a modified expandable polystyrene with excellent heat preservation, flame retardancy and mechanical properties. The synthesis of the modified dispersant is obtained by chemical cross-linking reaction between the aldehyde group in the structure of the modifier and the hydroxyl group in the structure of the dispersant. The modifier is firstly obtained by ring-opening reaction between the amino group in the structure of o-aminobenzaldehyde and the epoxy group in the structure of diphenylphosphite oxirane methyl ester to obtain an intermediate, and then the hydroxyl group in the intermediate structure is esterified with the carboxyl group in the structure of 2-bromo-3-fluoropyridine-6-carboxylic acid. The molecular structure of the modified dispersant contains phosphorus, fluorine and bromine elements. Among them, phosphorus has a good flame retardant effect and can react with free radicals generated during the combustion process. These free radicals are usually important participants in promoting the continued burning of the flame. By capturing free radicals, the combustion chain reaction can be interrupted and the spread of the flame can be inhibited; phosphorus can also promote the formation of a dense carbonized film in the composite material during the thermal decomposition process. This film can isolate oxygen from further contact with the composite material, thereby reducing the combustion rate. These effects can give the modified dispersant excellent flame retardant properties, thereby improving the flame retardant and fireproof properties of the modified expandable polystyrene. Fluorine-containing compounds can improve the thermal insulation properties of composite materials. Fluorine-containing compounds have low thermal conductivity and can effectively prevent heat from being conducted through the material, thereby reducing heat loss and improving the thermal insulation effect; fluorine-containing compounds can also maintain physical properties at higher temperatures, are not easy to deform or decompose, and ensure that they can also play an effective thermal insulation role in high-temperature application scenarios. Therefore, the modified dispersant also has good thermal insulation and high temperature resistance properties, thereby effectively improving the thermal insulation properties of the modified expandable polystyrene material. Bromine-containing compounds can bring good flame retardant effect to composite materials. They will decompose and generate bromine free radicals at high temperature. These bromine free radicals can react with highly active hydrogen free radicals and hydroxyl free radicals to generate relatively less active hydrogen bromide. Since the generation of hydrogen bromide reduces the concentration of highly active free radicals, it can effectively inhibit the oxidation chain reaction in the flame and slow down the combustion speed until the flame is extinguished. Therefore, the modified dispersant also has excellent flame retardancy, thereby improving the flame retardant properties of modified expandable polystyrene. In addition, phosphorus and bromine elements also have a synergistic effect, jointly inhibiting combustion and improving the fire resistance of composite materials. The selected dispersants are all cellulose derivatives, and their molecular structures contain a large number of hydroxyl groups. Therefore, the aldehyde groups on the molecular structure of the modifier can react chemically with the hydroxyl groups of the dispersant to form a three-dimensional network structure inside the material, improve the mechanical properties of the modified dispersant, and thus improve the mechanical properties of the modified expandable polystyrene.

[0016] The present invention successfully prepares modified expandable polystyrene by compounding raw materials such as styrene, calcium carbonate, modified dispersant, auxiliary dispersant, initiator and foaming agent. The expandable polystyrene has excellent flame retardant, mechanical and thermal insulation properties. In addition, by accurately controlling the ratio of each raw material and the reaction conditions, the overall performance of the modified expandable polystyrene can be further optimized, thereby improving its adaptability in different fields. Therefore, the modified expandable polystyrene and the preparation method thereof provided by the present invention show broad application prospects and market value. DETAILED DESCRIPTION

[0017] 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.

[0018] The raw materials used in the following examples are all common commercial products. Cellulose acetate has a density of 1.3 g / mL at 25 °C (lit.), an active ingredient content of 99%, a brand of Bashifu, purchased from Bashifu (Shanghai) Biomedical Technology Co., Ltd.; Hydroxyethyl cellulose has a viscosity (2% aqueous solution at 20 °C, mPa.s) of 28000-36000, an ash content of ≤3%, and a density of 1.16 g / cm 3 , brand is Huishuntong, purchased from Shandong Huishuntong New Materials Co., Ltd.; methyl cellulose has a methoxyl group (wt%) of 28.0-32.0, a drying loss (wt%) of ≤5, purchased from Guangzhou Shisheng Chemical Co., Ltd.; ethyl cellulose has a viscosity of N50, a particle size of 100 mesh, a brand of Yuhe, purchased from Hebei Kelongduo Biotechnology Co., Ltd.; fatty alcohol polyoxyethylene ether has an HLB value of 12.5, a pH value of 7, a brand of Jihua, purchased from Jinan Yuanfang Chemical Co., Ltd.; polyvinyl alcohol has a viscosity of 68.0-78.0 mPa·s, a model of 26-99L2488, purchased from Anhui Longyang Environmental Protection Technology Co., Ltd.; petroleum ether has a relative density (water = 1) of 0.64-0.66, and its main components are pentane and hexane, purchased from Wuhan Jiyesheng Chemical Co., Ltd. Calcium carbonate has a purity of 95% and a particle size of 200 mesh, purchased from Lingshou County Yuanda Mica Factory.

[0019] Example 1: A modified expandable polystyrene comprises the following raw materials in parts by weight: 110 parts of deionized water, 80 parts of styrene, 0.03 parts of calcium carbonate, 0.5 parts of modified dispersant, 0.1 parts of auxiliary dispersant, 0.3 parts of initiator, and 3 parts of foaming agent; The auxiliary dispersant is sodium dodecylbenzene sulfonate, the initiator is diisopropylbenzene peroxide, and the foaming agent is n-pentane; The preparation method of the modified dispersant is as follows: Step S1, adding o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine to N,N-dimethylformamide at 100° C. with stirring, reacting for 4 hours, cooling to room temperature and filtering to obtain a filtrate, then rotary evaporating the filtrate at 80° C. to remove N,N-dimethylformamide to obtain an intermediate, wherein the molar ratio of o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine is 1:1:0.02, and the amount of o-aminobenzaldehyde added to N,N-dimethylformamide is 0.09 g / mL; Step S2, uniformly mixing the intermediate obtained in step S1, 2-bromo-3-fluoropyridine-6-carboxylic acid and sodium ethoxide, reacting at 90° C. with stirring for 5 h, cooling to room temperature, and then extracting with ethyl acetate, taking the organic phase and distilling under reduced pressure to obtain a modifier, wherein the molar ratio of the intermediate, 2-bromo-3-fluoropyridine-6-carboxylic acid and sodium ethoxide is 1:0.8:0.002, and the mass volume ratio of the total amount of reactants to ethyl acetate is 1:20 g / mL; Step S3, adding the dispersant and the modifier obtained in step S2 to N,N-dimethylformamide at 40° C. with stirring, reacting for 90 minutes, cooling to room temperature, filtering to obtain a filtrate, and then rotary evaporating the filtrate at 80° C. to remove N,N-dimethylformamide to obtain a modified dispersant, wherein the molar ratio of the dispersant to the modifier is 1:0.09, the amount of the modifier added to the N,N-dimethylformamide is 0.09 g / mL, and the dispersant is cellulose acetate; The synthetic route of the modifier is as follows: ; ; The NMR results of the modifier are: 1 H NMR (300 MHz, acetone-d6) δ 10.36 (s, 1H), 8.99 (s, 1H), 8.46 (d, 1H), 8.06 (t, 1H), 7.72-7.75 (m, 5H), 7.44-7.47 (m, 7H), 7.01-7.03 (m, 2H), 4.32-4.62 (m, 3H), 3.34-3.59 (m, 2H).

[0020] A method for preparing modified expandable polystyrene comprises the following steps: (1) Deionized water, styrene, modified dispersant, auxiliary dispersant and initiator were added into a reactor, mixed evenly and heated to 90°C for 3.5 hours, then calcium carbonate was added and the reaction was continued for 30 minutes to obtain polystyrene particles; (2) Add a blowing agent to the polystyrene particles obtained in step (1), then heat the mixture to 108°C, react for 2 h, then heat the mixture to 119°C, continue to react for 4 h, then cool the mixture to 50°C, wash, dry, and discharge the mixture to obtain modified expandable polystyrene.

[0021] Example 2: A modified expandable polystyrene comprises the following raw materials in parts by weight: 120 parts of deionized water, 90 parts of styrene, 0.7 parts of calcium carbonate, 0.6 parts of a modified dispersant, 0.3 parts of an auxiliary dispersant, 0.5 parts of an initiator, and 4 parts of a foaming agent; The auxiliary dispersant is calcium phosphate, the initiator is tert-butyl perbenzoate, and the foaming agent is isopentane; The preparation method of the modified dispersant is as follows: Step S1, adding o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine to N,N-dimethylformamide at 110° C. with stirring, reacting for 3 hours, cooling to room temperature and filtering to obtain a filtrate, then rotary evaporating the filtrate at 20° C. to remove N,N-dimethylformamide to obtain an intermediate, wherein the molar ratio of o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine is 1:1.1:0.03, and the amount of o-aminobenzaldehyde added to N,N-dimethylformamide is 0.18 g / mL; Step S2, uniformly mixing the intermediate obtained in step S1, 2-bromo-3-fluoropyridine-6-carboxylic acid and sodium ethoxide, reacting at 100° C. with stirring for 4 hours, cooling to room temperature, and then extracting with ethyl acetate, taking the organic phase and distilling under reduced pressure to obtain a modifier, wherein the molar ratio of the intermediate, 2-bromo-3-fluoropyridine-6-carboxylic acid and sodium ethoxide is 1:0.9:0.004, and the mass volume ratio of the total amount of reactants to ethyl acetate is 1:50 g / mL; Step S3, adding the dispersant and the modifier obtained in step S2 to N,N-dimethylformamide at 60° C. with stirring, reacting for 60 minutes, cooling to room temperature, filtering to obtain a filtrate, and then rotary evaporating the filtrate at 80° C. to remove N,N-dimethylformamide to obtain a modified dispersant, wherein the molar ratio of the dispersant to the modifier is 1:0.1, the amount of the modifier added to the N,N-dimethylformamide is 0.13 g / mL, and the dispersant is hydroxyethyl cellulose; A method for preparing modified expandable polystyrene comprises the following steps: (1) Deionized water, styrene, modified dispersant, auxiliary dispersant and initiator were added into a reactor, mixed evenly and heated to 95°C for 2 hours, then calcium carbonate was added and the reaction was continued for 40 minutes to obtain polystyrene particles; (2) Add a blowing agent to the polystyrene particles obtained in step (1), then heat the mixture to 112°C, react for 1.5 hours, then heat the mixture to 121°C, continue to react for 3 hours, then cool the mixture to 55°C, wash, dry, and discharge the mixture to obtain modified expandable polystyrene.

[0022] Embodiment 3: A modified expandable polystyrene comprises the following raw materials in parts by weight: 115 parts of deionized water, 85 parts of styrene, 0.1 parts of calcium carbonate, 0.55 parts of a modified dispersant, 0.2 parts of an auxiliary dispersant, 0.4 parts of an initiator, and 3.5 parts of a foaming agent; The auxiliary dispersant is stearic acid, the initiator is tert-butyl peroxy-2-ethylhexanoate, and the foaming agent is isopentane; The preparation method of the modified dispersant is as follows: Step S1, adding o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine to N,N-dimethylformamide at 105° C. with stirring, reacting for 3.5 hours, cooling to room temperature and filtering to obtain a filtrate, then rotary evaporating the filtrate at 20° C. to remove N,N-dimethylformamide to obtain an intermediate, wherein the molar ratio of o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine is 1:1.05:0.025, and the amount of o-aminobenzaldehyde added to N,N-dimethylformamide is 0.12 g / mL; Step S2, uniformly mixing the intermediate obtained in step S1, 2-bromo-3-fluoropyridine-6-carboxylic acid and sodium ethoxide, reacting at 95° C. with stirring for 4.5 hours, cooling to room temperature, and then extracting with ethyl acetate, taking the organic phase and distilling under reduced pressure to obtain a modifier, wherein the molar ratio of the intermediate, 2-bromo-3-fluoropyridine-6-carboxylic acid and sodium ethoxide is 1:0.85:0.003, and the mass volume ratio of the total amount of reactants to ethyl acetate is 1:30 g / mL; Step S3, adding the dispersant and the modifier obtained in step S2 to N,N-dimethylformamide at 50° C. with stirring, reacting for 70 minutes, cooling to room temperature, filtering to obtain a filtrate, and then rotary evaporating the filtrate at 80° C. to remove N,N-dimethylformamide to obtain a modified dispersant, wherein the molar ratio of the dispersant to the modifier is 1:0.095, the amount of the modifier added to the N,N-dimethylformamide is 0.1 g / mL, and the dispersant is ethyl cellulose; A method for preparing modified expandable polystyrene comprises the following steps: (1) Deionized water, styrene, modified dispersant, auxiliary dispersant and initiator were added into a reactor, mixed evenly and heated to 92°C for 3 hours, then calcium carbonate was added and the reaction was continued for 35 minutes to obtain polystyrene particles; (2) Add a blowing agent to the polystyrene particles obtained in step (1), then heat the mixture to 110°C, react for 1.7 hours, then heat the mixture to 120°C, continue to react for 3.5 hours, then cool the mixture to 52°C, wash, dry, and discharge the mixture to obtain modified expandable polystyrene.

[0023] Comparative Example 1: A modified expandable polystyrene, comprising the following raw materials in parts by weight: 115 parts of deionized water, 85 parts of styrene, 0.1 parts of calcium carbonate, 0.55 parts of modified dispersant, 0.2 parts of auxiliary dispersant, 0.4 parts of initiator, and 3.5 parts of foaming agent; The auxiliary dispersant is stearic acid, the initiator is tert-butyl peroxy-2-ethylhexanoate, and the foaming agent is isopentane; The preparation method of the modified dispersant is as follows: Step S1, adding o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine to N,N-dimethylformamide at 105° C. with stirring, reacting for 3.5 hours, cooling to room temperature and filtering to obtain a filtrate, then rotary evaporating the filtrate at 20° C. to remove N,N-dimethylformamide to obtain a modifier, wherein the molar ratio of o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine is 1:1.05:0.025, and the amount of o-aminobenzaldehyde added to N,N-dimethylformamide is 0.12 g / mL; Step S2, adding the dispersant and the modifier obtained in step S1 to N,N-dimethylformamide at 50° C. with stirring, reacting for 70 minutes, cooling to room temperature, filtering to obtain a filtrate, and then rotary evaporating the filtrate at a temperature of 80° C. to remove N,N-dimethylformamide to obtain a modified dispersant, wherein the molar ratio of the dispersant to the modifier is 1:0.095, the amount of the modifier added to the N,N-dimethylformamide is 0.1 g / mL, and the dispersant is ethyl cellulose; The preparation method of a modified expandable polystyrene is the same as that in Example 3.

[0024] Comparative Example 2: A modified expandable polystyrene, comprising the following raw materials in parts by weight: 115 parts of deionized water, 85 parts of styrene, 0.1 parts of calcium carbonate, 0.55 parts of dispersant, 0.2 parts of auxiliary dispersant, 0.4 parts of initiator, and 3.5 parts of foaming agent; The dispersant is ethyl cellulose, the auxiliary dispersant is stearic acid, the initiator is tert-butyl peroxy-2-ethylhexanoate, and the foaming agent is isopentane; The difference between the method for preparing modified expandable polystyrene and Example 3 is that the modified dispersant in step (1) is replaced by a dispersant, and the rest is the same as Example 3.

[0025] Comparative Example 3: A modified expandable polystyrene, comprising the following raw materials in parts by weight: 100 parts of deionized water, 70 parts of styrene, 0.01 parts of calcium carbonate, 0.1 parts of modified dispersant, 0.1 parts of auxiliary dispersant, 0.1 parts of initiator, and 1 part of foaming agent; The auxiliary dispersant is stearic acid, the initiator is tert-butyl peroxy-2-ethylhexanoate, and the foaming agent is isopentane; The preparation method of the modified dispersant is as follows: Step S1, adding o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine to N,N-dimethylformamide at 80° C. with stirring, reacting for 4 hours, cooling to room temperature and filtering to obtain a filtrate, then rotary evaporating the filtrate at 20° C. to remove N,N-dimethylformamide to obtain an intermediate, wherein the molar ratio of o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine is 1:2:0.01, and the amount of o-aminobenzaldehyde added to N,N-dimethylformamide is 0.12 g / mL; Step S2, uniformly mixing the intermediate obtained in step S1, 2-bromo-3-fluoropyridine-6-carboxylic acid and sodium ethoxide, reacting at 80° C. with stirring for 4.5 hours, cooling to room temperature, and then extracting with ethyl acetate, taking the organic phase and distilling under reduced pressure to obtain a modifier, wherein the molar ratio of the intermediate, 2-bromo-3-fluoropyridine-6-carboxylic acid and sodium ethoxide is 1:2:0.001, and the mass volume ratio of the total amount of reactants to ethyl acetate is 1:30 g / mL; Step S3, adding the dispersant and the modifier obtained in step S2 to N,N-dimethylformamide at room temperature and under stirring, reacting for 90 minutes, cooling to room temperature, filtering to obtain a filtrate, and then rotary evaporating the filtrate at a temperature of 80° C. to remove N,N-dimethylformamide to obtain a modified dispersant, wherein the molar ratio of the dispersant to the modifier is 1:0.095, the amount of the modifier added to the N,N-dimethylformamide is 0.1 g / mL, and the dispersant is ethyl cellulose; The preparation method of a modified expandable polystyrene is the same as that in Example 3.

[0026] The properties of the modified expandable polystyrene prepared in Examples 1-3 and Comparative Examples 1-3 were tested. The testing method is as follows. The test results are shown in Table 1 below.

[0027] Before conducting the following tests, the modified expandable polystyrene prepared in Examples 1-3 and Comparative Examples 1-3 was prepared into modified expandable polystyrene boards, which were first foamed at a foaming temperature of 100°C and a steam pressure of 2.5 kg / m³, and then formed by a plate forming machine at a steam pressure of 3.5 kg / m³. The sample size was determined according to the test requirements.

[0028] (1) Mechanical properties The tensile strength test was carried out in accordance with GB 9641-1988 “Test method for tensile properties of rigid cellular plastics”; the flexural strength test was carried out in accordance with GB / T8812.2-2007 “Determination of flexural properties of rigid cellular plastics Part 2: Determination of flexural strength and apparent flexural modulus of elasticity”.

[0029] (2) Thermal insulation performance The thermal conductivity test is carried out in accordance with GB / T 10294-2008 "Determination of steady-state thermal resistance and related properties of insulation materials - Guarded hot plate method".

[0030] (3) Flame retardant properties The modified expandable polystyrene board was made into a sample board with a size of (80±2) mm×(10±0.5) mm×(4±0.25) mm, and then the oxygen index value was tested in accordance with GB / T 2406.2-2009 "Determination of Combustion Behavior of Plastics by Oxygen Index Method Part 2: Room Temperature Test"; the modified expandable polystyrene board was made into a sample board with a size of 250 mm×90 mm×60 mm, and then the sample boards were graded in accordance with GB 8624-2012 "Classification of Combustion Performance of Building Materials and Products".

[0031] Table 1 Performance test of sample plates prepared from modified expandable polystyrene:

[0032] Modified expandable polystyrene was prepared in Examples 1-3. As shown in Table 1, the tensile properties, bending resistance, thermal insulation properties and flame retardant properties of the modified expandable polystyrene board prepared therefrom are greatly improved compared with Comparative Examples 1-3. Specifically, by modifying the dispersant and optimizing the ratio of the raw materials in the modified expandable polystyrene, the prepared modified expandable polystyrene board exhibits higher tensile strength and enhances its durability against external forces. In addition, in the bending test, the board exhibits better bending strength and effectively resists bending deformation. In terms of thermal insulation performance, the modified polystyrene board has a lower thermal conductivity, providing a more outstanding thermal insulation effect for applications such as construction and refrigeration. At the same time, the introduction of the modified dispersant also significantly improves the flame retardant properties of the modified expandable polystyrene board, making the material more suitable for various environments requiring fire protection on the basis of meeting safety standards. Therefore, the boards made from the modified expandable polystyrene prepared in Examples 1-3 show superiority in various key properties, further broadening the application field of modified expandable polystyrene.

[0033] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0034] 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 modified expandable polystyrene, characterized in that: The invention comprises the following raw materials in parts by weight: 110-120 parts of deionized water, 80-90 parts of styrene, 0.03-0.7 parts of calcium carbonate, 0.5-0.6 parts of modified dispersant, 0.1-0.3 parts of auxiliary dispersant, 0.3-0.5 parts of initiator, and 3-4 parts of foaming agent; the preparation method of the modified dispersant is as follows: Step S1, adding o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine to N,N-dimethylformamide at 100-110° C. with stirring, reacting for 3-4 hours, cooling to room temperature, removing the solvent, and obtaining an intermediate, the structural formula of the intermediate is: ； Step S2, the intermediate obtained in step S1, 2-bromo-3-fluoropyridine-6-carboxylic acid and sodium ethoxide are uniformly mixed, reacted at 90-100° C. with stirring for 4-5 hours, cooled to room temperature, purified, and obtained a modifier having the structural formula of: ； Step S3, adding the dispersant and the modifier obtained in step S2 to N,N-dimethylformamide at 40-60° C. with stirring, reacting for 60-90 minutes, cooling to room temperature, and purifying to obtain a modified dispersant.

2. The modified expandable polystyrene according to claim 1, characterized in that: The molar ratio of o-aminobenzaldehyde, diphenylphosphite oxirane methyl ester and triphenylphosphine in step S1 is 1:1-1.1:0.02-0.03, and the amount of o-aminobenzaldehyde added to N,N-dimethylformamide is 0.09-0.18 g / mL.

3. The modified expandable polystyrene according to claim 1, characterized in that: The molar ratio of the intermediate, 2-bromo-3-fluoropyridine-6-carboxylic acid and sodium ethoxide in step S2 is 1:0.8-0.9:0.002-0.

004.

4. The modified expandable polystyrene according to claim 1, characterized in that: The molar ratio of the dispersant to the modifier in step S3 is 1:0.09-0.1, and the amount of the modifier added to N,N-dimethylformamide is 0.09-0.13 g / mL.

5. The modified expandable polystyrene according to claim 1, characterized in that: The dispersant in step S3 is one or more of cellulose acetate, hydroxyethyl cellulose, methyl cellulose, and ethyl cellulose.

6. The modified expandable polystyrene according to claim 1, characterized in that: The auxiliary dispersant is one or more of sodium dodecylbenzene sulfonate, calcium phosphate, stearic acid, fatty alcohol polyoxyethylene ether, and polyvinyl alcohol.

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

8. The modified expandable polystyrene according to claim 1, characterized in that: The foaming agent is one or more of n-pentane, isopentane, petroleum ether and butane.

9. The method for preparing modified expandable polystyrene according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Add deionized water, styrene, modified dispersant, auxiliary dispersant and initiator into a reactor, mix well and heat to 90-95°C, react for 2-3.5 hours, then add calcium carbonate and continue to react for 30-40 minutes to obtain polystyrene particles; (2) Add a blowing agent to the polystyrene particles obtained in step (1), then heat the mixture to 108-112°C, react for 1.5-2h, then heat the mixture to 119-121°C, continue to react for 3-4h, then cool the mixture to 50-55°C, wash, dry, and discharge the mixture to obtain modified expandable polystyrene.

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