Coated modified polystyrene pre-expanded particle as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of building materials, and particularly discloses coated modified polystyrene pre-expanded particles as well as a preparation method and application thereof. According to the invention, expandable graphite modified polystyrene particles with a certain flame retardant effect are used as a raw material, and phenolic resin with good char forming property, low smoke generation amount, low toxicity and good thermal stability is used as an adhesive; a composite flame retardant containing melamine, brucite, boric acid, organic modified montmorillonite and the like, carbon nanofibers and nano silicon dioxide are used as a coating layer, and the modified polystyrene pre-expanded particles with excellent flame retardant property and mechanical property are prepared. The invention also provides a preparation method of the coated modified polystyrene pre-expanded particle. The preparation method has the advantages of simple process, easily available raw materials, easiness in popularization and application and the like. The preparation method can be used in the field of preparation of building walls or flame-retardant plates.

Description

Technical Field

[0001] The invention belongs to the field of building materials, and in particular relates to a coated modified polystyrene pre-expanded particle and a preparation method and application thereof. Background Art

[0002] Organic insulation materials represented by polystyrene foam insulation boards are widely used in the field of building exterior wall insulation due to their many advantages such as light weight, thermal insulation, excellent mechanical properties, convenient construction, and low cost, and have a market share of more than 90% of building energy-saving insulation materials. However, traditional polystyrene foam insulation boards are extremely easy to burn due to their own thermoplasticity, and they release a large amount of heat and toxic gases when burning. Uninterrupted combustion and the formation of melt droplets will cause large-scale spread of fire. At the same time, with the implementation of a series of policies such as building fire protection regulations, it is urgent to improve the flame retardant properties of polystyrene boards. However, the flame retardant grade polystyrene foam insulation boards currently on the market generally have problems such as low flame retardancy and poor controllability. In view of these problems, it is of great significance to prepare a new type of flame retardant modified polystyrene foam insulation board with high efficiency flame retardancy and excellent mechanical properties. Summary of the invention The purpose of the present invention is to provide a coated modified polystyrene pre-expanded particle to meet and adapt to the current demand for flame retardant polystyrene board.

[0003] The second object of the present invention is to provide a method for preparing the above-mentioned coated modified polystyrene pre-expanded particles, thereby providing an industrializable production solution for the preparation of the polystyrene particles.

[0004] The third object of the present invention is to provide the above-mentioned coated modified polystyrene pre-expanded particles for use in flame retardant boards, which can achieve Class A fire resistance under certain conditions, thereby providing users with more flame retardant board options.

[0005] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: In a first aspect, the present invention provides a coated modified polystyrene pre-expanded particle, which comprises the following components in parts by weight: 70 to 80 parts of expandable graphite modified polystyrene particles, 8 to 10 parts of a composite flame retardant, 2 to 4 parts of carbon nanofibers, 2 to 4 parts of nano silicon dioxide, and 40 to 70 parts of a coating agent; Wherein, the composite flame retardant comprises melamine, brucite, boric acid and organic modified montmorillonite; The organic modified montmorillonite is a gemini quaternary ammonium salt modified montmorillonite; The structural formula of gemini quaternary ammonium salt is: .

[0006] The present invention uses expandable graphite-modified polystyrene particles with a certain flame retardant effect as raw materials, uses a phenolic resin with good carbonization, low smoke generation, low toxicity and good thermal stability as an adhesive, and coats a composite flame retardant including melamine, brucite, boric acid and organic modified montmorillonite, as well as carbon nanofibers and nano-silicon dioxide as a coating layer to prepare a modified polystyrene pre-expanded particle with excellent flame retardant properties and mechanical properties. During the combustion process, the flame retardant coating layer not only acts on the surface of the base material, but can also quickly form a thermally stable carbon layer to block the transfer of flame and heat to the base, thereby achieving the effect of flame retardancy and smoke suppression; it can also be combined with the phenolic resin to increase the encapsulation rate. The flame retardant coating layer is achieved through the mechanisms of gas phase flame retardancy, condensed phase flame retardancy and intermittent heat exchange flame retardancy during the combustion process. These flame retardant mechanisms interact with each other and jointly affect the flame retardant properties of the product. For example, when phenolic resin, magnesium hydroxide and boric acid are heated and decomposed, a large amount of non-combustible gases such as NH3, N2 and water vapor will be produced. The gas phase flame retardant effect dilutes the concentration of the combustible gas. Then, the combustion speed of the flame retardant sample slows down and the residual carbon content increases. In addition, the metal compounds formed by the decomposition of magnesium hydroxide and boric acid can form a protective insulation layer to prevent further decomposition of the EPS matrix, increase the residual carbon content, and also provide a good solid phase flame retardant effect.

[0007] In the present invention, the carbon nanofibers and nano silicon dioxide can not only improve the mechanical properties of the obtained coated modified polystyrene pre-expanded particles, but also have a flame retardant effect.

[0008] In order to make the coated modified polystyrene pre-expanded particles provided by the present invention have excellent fire resistance, the present invention has developed a flame retardant system based on a combination of multiple flame retardants. The melamine in the composite flame retardant, the magnesium hydroxide in the brucite, the boric acid and the organic modified montmorillonite work together with the phenolic resin and the nanomaterials (carbon nanofibers and nanosilicon dioxide, which have the functions of physical barrier, heat absorption and carbonization promotion) to improve the LOI value of the composite material and achieve the purpose of effective flame retardancy and improved thermal stability. This may be attributed to the secondary reactions (such as hydrogen extraction, free radical recombination reaction, extensive random cracking, various intermolecular reactions, etc.) inside the flame retardant system selected by the present invention, and the synergistic flame retardant effect between different flame retardants.

[0009] Among them, during the combustion process, melamine will produce inert gases such as ammonia and nitrogen, which will deplete oxygen and combustible gases and also have a smoke suppression effect; magnesium hydroxide can not only use the water vapor released by decomposition to dilute the combustion gas and block the air to achieve flame retardancy during combustion, but also has the effects of high dehydration temperature, promoting carbonization, and is not easy to produce bubbles during the molding process. Compared with conventional montmorillonite, gemini quaternary ammonium salt-modified montmorillonite not only has better compatibility with polystyrene, but also can effectively promote the carbonization of polystyrene and prevent further combustion of the matrix, thereby improving the product's anti-melting droplet performance. Boric acid and magnesium hydroxide in brucite have a synergistic flame retardant effect in the gas phase and condensation phase, which can improve the thermal stability and LOI value of the composite material; the combination of melamine and magnesium hydroxide, and the combination of organic modified montmorillonite and boric acid will also improve the LOI value of the composite material.

[0010] Preferably, the preparation method of the gemini quaternary ammonium salt comprises the following steps: adding tetramethylethylenediamine to an ethanol solution of 1-chloropentane, reacting at 58° C. to 62° C. for 11 h to 13 h to obtain the gemini quaternary ammonium salt; Wherein, the molar ratio of tetramethylethylenediamine to 1-chloropentane is 1:2.1-2.3.

[0011] Preferably, the method for preparing the gemini quaternary ammonium salt modified montmorillonite comprises the following steps: mixing a montmorillonite suspension with a gemini quaternary ammonium salt solution to obtain a mixed suspension, and reacting at 78° C. to 82° C. for 3 h to 4 h to obtain the gemini quaternary ammonium salt modified montmorillonite.

[0012] The mass ratio of the gemini quaternary ammonium salt to montmorillonite in the mixed suspension is 1.3:3 to 1.6:3; The mass concentration of the montmorillonite suspension is 40g / L to 50g / L; The mass concentration of the gemini quaternary ammonium salt solution is 45g / L~55g / L.

[0013] Montmorillonite (MMT) is mainly composed of hydroaluminosilicate, and although it has a high specific heat capacity, good adsorption, barrier properties, flame retardancy and thermal stability, etc., montmorillonite is hydrophilic and oleophobic and is very easy to agglomerate. In order to improve the compatibility of montmorillonite with polymer matrix, it is often subjected to organic modification. The gemini quaternary ammonium salt modified montmorillonite in the present invention not only has the function of adsorbing composite flame retardant, but also can improve the compatibility with polystyrene.

[0014] Preferably, the weight ratio of melamine, brucite, boric acid and organically modified montmorillonite is 1:1.5~3:1~3:6~8.

[0015] Preferably, the particle size of the expandable graphite-modified polystyrene particles is 0.9 mm to 1.6 mm; The magnesium hydroxide content (calculated as magnesium oxide) in the brucite is 60% to 70%.

[0016] Compared with aluminum hydroxide, magnesium hydroxide can not only use the water vapor released by decomposition to dilute the combustion gas and block the air to achieve flame retardancy during combustion, but also has the functions of high dehydration temperature and carbon promotion, and is not easy to generate bubbles during the molding process. Therefore, the present invention selects brucite rich in magnesium hydroxide, which can not only save costs, but also has a synergistic effect with other flame retardants such as nitrogen flame retardants and boric acid.

[0017] Preferably, the coating agent comprises at least two of silica sol, water glass and phenolic resin; wherein the concentration of the silica sol is 30% to 40%; the water glass comprises sodium water glass or potassium water glass, and its modulus is 2.5 to 3.5; and the solid content of the phenolic resin is 45% to 55%.

[0018] In addition, the carbon nanofibers in the present invention have a diameter of 75nm±25nm and a length of 1-15μm; and the nano-silicon dioxide particle size is 15-25nm.

[0019] In a second aspect, the present invention further provides a method for preparing the above-mentioned coated modified polystyrene pre-expanded particles, the preparation method comprising the following steps: Step 1: pre-expanding the expandable graphite-modified polystyrene particles to obtain initial pre-expanded particles; The composite flame retardant, carbon nanofiber, nano silicon dioxide and coating agent are mixed to obtain coating slurry; Step 2, adding the coating slurry to the initial pre-fermented granular material to obtain coated granular material; Step 3: Ripening, drying and dispersing the coated particle material to obtain coated modified polystyrene pre-expanded particles.

[0020] The preparation method of the brucite added in the present invention comprises: washing and drying a high-purity brucite concentrate having a magnesium hydroxide content (calculated as magnesium oxide) of 60% to 70%, and then grinding the concentrate into a powder of about 325 meshes by using a wet all-ceramic ball mill under the action of a grinding aid.

[0021] In step 1, when other raw materials are mixed with the coating agent, according to the common knowledge of those skilled in the art, an appropriate amount of p-toluenesulfonic acid, benzenesulfonic acid, phthalic anhydride, hydrochloric acid, sulfuric acid or phosphoric acid can also be added as a curing agent according to conventional techniques.

[0022] The preparation method provided by the invention has the advantages of simple preparation process, readily available raw materials, easy promotion and application, etc.

[0023] Preferably, the particle size of the initial pre-expanded granular material is 5 mm to 8 mm.

[0024] Preferably, the aging is carried out at a temperature of 100° C. to 115° C. and for a time of 3 min to 12 min.

[0025] In a third aspect, the present invention also provides the use of the above-mentioned coated modified polystyrene pre-expanded particles in the preparation of flame retardant boards.

[0026] The polystyrene board prepared by the coated modified polystyrene pre-expanded particles prepared by the present invention has the characteristics of low thermal conductivity and high flame retardancy while meeting the requirements of mechanical properties, and the obtained polystyrene board can reach the fire resistance Class A standard.

[0027] Since the coated modified polystyrene pre-expanded particles provided by the present invention have excellent flame retardant properties, they can be further applied to the field of building walls. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] Example 1 This embodiment provides a coated modified polystyrene pre-expanded particle, which includes the following components in parts by weight: 70 parts of expandable graphite modified polystyrene particles, 8 parts of composite flame retardant, 4 parts of carbon nanofibers, 2 parts of nano silicon dioxide and 40 parts of coating agent; The composite flame retardant is composed of melamine, brucite, boric acid and organic modified montmorillonite in a weight ratio of 1:1.5:2:6; The coating agent is composed of 20 parts of potassium water glass with a modulus of 3 and 43° Be and 20 parts of phenolic resin with a concentration of 45%; The carbon nanofiber has a diameter of 75nm±25nm and a length of 1-15μm; the nano-silicon dioxide particle size is 25nm; The organic modified montmorillonite is a gemini quaternary ammonium salt modified montmorillonite; wherein the structural formula of the gemini quaternary ammonium salt is: .

[0030] Wherein, the preparation method of the organic modified montmorillonite comprises the following steps: (1) Preparation of Gemini Quaternary Ammonium Salts Tetramethylethylenediamine was slowly added dropwise to the ethanol solution of 1-chloropentane, and the molar ratio of tetramethylethylenediamine to 1-chloropentane was controlled to be 1:2.2. During the addition, the system temperature was controlled not to exceed 30°C. After the addition was completed, the temperature was raised to 58°C and refluxed for 13 hours. After removing the solvent, a light yellow substance was obtained, which was then washed with acetone for 3 times, filtered to obtain a white solid, and dried in vacuo to obtain the target product; The above target product contains quaternary ammonium salt N + The characteristic peaks indicate that the target product is a gemini quaternary ammonium salt, and its structural formula is: .

[0031] (2) Preparation of Gemini quaternary ammonium salt modified montmorillonite Mix montmorillonite and deionized water, heat in a water bath at 80°C and stir mechanically until uniformly dispersed, to obtain a montmorillonite suspension with a mass concentration of 40 g / L. Weigh the above-prepared gemini quaternary ammonium salt and deionized water, stir thoroughly until completely dissolved, to obtain a gemini quaternary ammonium salt solution with a mass concentration of 55 g / L. Mix the above gemini quaternary ammonium salt solution with the montmorillonite suspension to obtain a mixed suspension, stir mechanically at 80°C for 2.5 hours, then centrifuge and wash the mixed suspension with deionized water for 3 times, dry to constant weight, and grind to 300 mesh to obtain gemini quaternary ammonium salt modified montmorillonite.

[0032] Wherein, the mass ratio of the gemini quaternary ammonium salt to montmorillonite in the mixed suspension is 1.3:3.

[0033] In this embodiment, the expandable graphite-modified polystyrene particles are purchased from Tianjin Stanley New Materials Co., Ltd.

[0034] This embodiment also provides a method for preparing the above-mentioned coated modified polystyrene pre-expanded particles, and the preparation method comprises the following steps: Step 1: pre-expand expandable graphite-modified polystyrene particles with a particle size of 0.9 mm to 1.6 mm with steam, and select initial pre-expanded particles with a particle size of 5 mm to 8 mm; Add melamine, brucite, boric acid, organic modified montmorillonite, carbon nanofiber, and nano silicon dioxide to a mixture of sodium water glass and phenolic resin, add an appropriate amount of phthalic anhydride, mix well, and obtain a coating slurry; Step 2: adding the coating slurry to the initial pre-fermented granular material, mixing thoroughly, and coating uniformly to obtain coated granular material; Step 3: Place the coated particle material in a forced air drying oven at 115° C. for 3 minutes, and after drying and dispersion, obtain coated modified polystyrene pre-expanded particles, which are recorded as modified polystyrene pre-expanded particles I.

[0035] Example 2 This embodiment provides a coated modified polystyrene pre-expanded particle, which includes the following components in parts by weight: 80 parts of expandable graphite modified polystyrene particles, 10 parts of a composite flame retardant, 2 parts of carbon nanofibers, 4 parts of nano silicon dioxide, and 70 parts of a coating agent; The composite flame retardant is composed of melamine, brucite, boric acid and organic modified montmorillonite in a weight ratio of 1:3:3:8; The coating agent is composed of 20 parts of sodium water glass with a modulus of 3.2 and 40° Be, 20 parts of silica sol with a concentration of 30%, and 30 parts of phenolic resin with a concentration of 55%; The carbon nanofiber has a diameter of 75nm±25nm and a length of 1-15μm; the nano-silicon dioxide particle size is 20nm; The organic modified montmorillonite is a gemini quaternary ammonium salt modified montmorillonite; wherein the structural formula of the gemini quaternary ammonium salt is: .

[0036] Wherein, the preparation method of the organic modified montmorillonite comprises the following steps: (1) Preparation of Gemini Quaternary Ammonium Salts Tetramethylethylenediamine was slowly added dropwise to the ethanol solution of 1-chloropentane, and the molar ratio of tetramethylethylenediamine to 1-chloropentane was controlled to be 1:2.1. The system temperature was controlled not to exceed 30°C during the addition. After the addition was completed, the temperature was raised to 65°C and refluxed for 11 hours. After removing the solvent, a light yellow substance was obtained, which was then washed with acetone for 3 times, filtered to obtain a white solid, and dried in vacuo to obtain the target product; The above target product contains quaternary ammonium salt N + The characteristic peaks indicate that the target product is a gemini quaternary ammonium salt, and its structural formula is: .

[0037] (2) Preparation of Gemini quaternary ammonium salt modified montmorillonite Mix montmorillonite and deionized water, heat in a water bath at 80°C and stir mechanically until uniformly dispersed, to obtain a montmorillonite suspension with a mass concentration of 45 g / L. Weigh the above-prepared gemini quaternary ammonium salt and deionized water, stir thoroughly until completely dissolved, to obtain a gemini quaternary ammonium salt solution with a mass concentration of 50 g / L. Mix the above gemini quaternary ammonium salt solution with the montmorillonite suspension to obtain a mixed suspension, stir mechanically at 80°C for 3h, then centrifuge and wash the mixed suspension with deionized water for 3 times, dry to constant weight, and grind to 300 mesh to obtain gemini quaternary ammonium salt modified montmorillonite.

[0038] Wherein, the mass ratio of gemini quaternary ammonium salt to montmorillonite in the mixed suspension is 1.6:3.

[0039] In this embodiment, the expandable graphite-modified polystyrene particles selected are commercially available products.

[0040] This embodiment also provides a method for preparing the above-mentioned coated modified polystyrene pre-expanded particles, and the preparation method comprises the following steps: Step 1: pre-expand expandable graphite-modified polystyrene particles with a particle size of 0.9 mm to 1.6 mm with steam, and select initial pre-expanded particles with a particle size of 5 mm to 8 mm; Add melamine, brucite, boric acid, organic modified montmorillonite, carbon nanofiber, and nano silicon dioxide to a mixture of sodium water glass and phenolic resin, add an appropriate amount of phthalic anhydride, mix well, and obtain a coating slurry; Step 2: adding the coating slurry to the initial pre-fermented granular material, mixing thoroughly, and coating uniformly to obtain coated granular material; Step 3: Place the coated particle material in a forced air drying oven at 100° C. for 12 minutes, and after drying and dispersion, obtain coated modified polystyrene pre-expanded particles, which are recorded as modified polystyrene pre-expanded particles II.

[0041] Example 3 This embodiment provides a coated modified polystyrene pre-expanded particle, which includes the following components in parts by weight: 75 parts of expandable graphite modified polystyrene particles, 9 parts of composite flame retardant, 3 parts of carbon nanofibers, 3 parts of nano silicon dioxide and 60 parts of coating agent; Wherein, the composite flame retardant is composed of melamine, brucite, boric acid and organic modified montmorillonite in a weight ratio of 1:2:1:7; The coating agent is composed of 15 parts of sodium water glass with a modulus of 3.2 and 40° Be, 25 parts of silica sol with a concentration of 40%, and 20 parts of phenolic resin with a concentration of 50%; The carbon nanofiber has a diameter of 75nm±25nm and a length of 1-15μm; the nano-silicon dioxide particle size is 25nm; The organic modified montmorillonite is a gemini quaternary ammonium salt modified montmorillonite; wherein the structural formula of the gemini quaternary ammonium salt is: .

[0042] Wherein, the preparation method of the organic modified montmorillonite comprises the following steps: (1) Preparation of Gemini Quaternary Ammonium Salts Tetramethylethylenediamine was slowly added dropwise to the ethanol solution of 1-chloropentane, and the molar ratio of tetramethylethylenediamine to 1-chloropentane was controlled to be 1:2.3. The temperature of the system was controlled not to exceed 30°C during the addition. After the addition was completed, the temperature was raised to 60°C and refluxed for 12 hours. After removing the solvent, a light yellow substance was obtained, which was then washed with acetone for 3 times, filtered to obtain a white solid, and dried in vacuo to obtain the target product; The above target product contains quaternary ammonium salt N + The characteristic peaks indicate that the target product is a gemini quaternary ammonium salt, and its structural formula is: .

[0043] (2) Preparation of Gemini quaternary ammonium salt modified montmorillonite Mix montmorillonite and deionized water, heat in a water bath at 80°C and stir mechanically until uniformly dispersed, to obtain a montmorillonite suspension with a mass concentration of 50 g / L. Weigh the above-prepared gemini quaternary ammonium salt and deionized water, stir thoroughly until completely dissolved, to obtain a gemini quaternary ammonium salt solution with a mass concentration of 45 g / L. Mix the above gemini quaternary ammonium salt solution with the montmorillonite suspension to obtain a mixed suspension, stir mechanically at 80°C for 3 hours, then centrifuge and wash the mixed suspension with deionized water for 3 times, dry to constant weight, and grind to 300 mesh to obtain gemini quaternary ammonium salt modified montmorillonite.

[0044] Wherein, the mass ratio of gemini quaternary ammonium salt to montmorillonite in the mixed suspension is 1.5:3.

[0045] In this embodiment, the expandable graphite-modified polystyrene particles selected are commercially available products.

[0046] This embodiment also provides a method for preparing the above-mentioned coated modified polystyrene pre-expanded particles, and the preparation method comprises the following steps: Step 1: pre-expand expandable graphite-modified polystyrene particles with a particle size of 0.9 mm to 1.6 mm with steam, and select initial pre-expanded particles with a particle size of 5 mm to 8 mm; Add melamine, brucite, boric acid, organic modified montmorillonite, carbon nanofiber, and nano silicon dioxide to a mixture of sodium water glass and phenolic resin, add an appropriate amount of phthalic anhydride, mix well, and obtain a coating slurry; Step 2: adding the coating slurry to the initial pre-fermented granular material, mixing thoroughly, and coating uniformly to obtain coated granular material; Step 3: Place the coated particle material in a forced air drying oven at 105° C. for 8 minutes, and after drying and dispersion, obtain coated modified polystyrene pre-expanded particles, which are recorded as modified polystyrene pre-expanded particles III.

[0047] Comparative Example 1 Comparative Example 1 provides a coated modified polystyrene pre-expanded particle. The raw material composition and preparation method of the coated modified polystyrene pre-expanded particle provided in this comparative example are basically the same as those in Example 3, except that: in terms of raw materials, "organic modified montmorillonite" is replaced by "montmorillonite", melamine is not added to the composite flame retardant, "the weight ratio of melamine, brucite, boric acid and organic modified montmorillonite in the composite flame retardant is 1:2:1:7" is changed to "the weight ratio of brucite, boric acid and montmorillonite in the composite flame retardant is 3:1:7", the total number of the composite flame retardant remains unchanged, and the types and amounts of the other raw materials are the same as those in Example 3; In terms of the preparation method, the above raw materials were replaced accordingly, and the other preparation parameters were the same as those in Example 3. The obtained product was recorded as modified polystyrene pre-expanded particles pair I.

[0048] Comparative Example 2 Comparative Example 1 provides a coated modified polystyrene pre-expanded particle. The raw material composition and preparation method of the coated modified polystyrene pre-expanded particle provided in this comparative example are basically the same as those in Example 3, except that: brucite and boric acid are not added to the composite flame retardant, and "the weight ratio of melamine, brucite, boric acid and organic modified montmorillonite in the composite flame retardant is 1:2:1:7" is changed to "the weight ratio of melamine and organic modified montmorillonite in the composite flame retardant is 4:7", the total number of the composite flame retardant remains unchanged, and the types and amounts of the other raw materials are the same as those in Example 3; In terms of the preparation method, the above raw materials were replaced accordingly, and the other preparation parameters were the same as those in Example 3. The obtained product was recorded as modified polystyrene pre-expanded particles pair II.

[0049] Effect example The modified polystyrene pre-expanded particles I to III and modified polystyrene pre-expanded particle pairs I to II prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were sucked into a board machine respectively, and foamed for 10 min under 130° C. water vapor and a pressure of 0.5 MPa to obtain modified polystyrene boards I to III and modified polystyrene board pairs I to II, and their performance was tested according to the following standards.

[0050] Determine the thermal conductivity of different products according to GB / T10294-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Insulating Materials - Guarded Hot Plate Method"; Determine the fire rating of different products according to GB8624-2019 "Classification of Combustion Performance of Building Materials and Products"; The compressive strength of different products is measured in accordance with GB / T 10801.1-2021 "Molded polystyrene foam (EPS) for thermal insulation".

[0051] The specific measurement results are shown in Table 1.

[0052] Table 1

[0053] As can be seen from the data in Table 1, by screening and reasonably proportioning the types of flame retardants, the technical solution provided in the embodiment of the present invention can produce a material with a fireproof grade of Class A, while reducing the types of raw materials in the composite flame retardant and changing the proportion, and its flame retardant effect is significantly reduced. Compared with the polystyrene board with the addition of conventional montmorillonite, the compressive strength of the polystyrene board provided in Example 3 of the present invention can be significantly improved, and the reason may be that the adhesion between the organic modified montmorillonite and the polystyrene interface is stronger. After removing melamine, brucite or boric acid from the composite flame retardant, even if the total number of composite flame retardants remains unchanged, the LOI value of the obtained board is significantly reduced compared with the board obtained from the material obtained in Example 3, and the reason is that there is a synergistic effect inside the flame retardant system. Among them, boric acid and magnesium hydroxide in brucite have synergistic flame retardant effects in the gas phase and condensation phase. After compounding, they can not only improve the thermal stability by increasing the carbon percentage and reducing the mass loss rate of the composite material, but also improve the LOI value of the composite material; the combination of melamine and magnesium hydroxide, and the combination of organically modified montmorillonite and boric acid will also increase the LOI value of the composite material.

[0054] The polystyrene board prepared by coating modified polystyrene pre-expanded particles provided by the present invention not only has good thermal insulation performance, but also has a high fire resistance grade, and can be widely used in the field of building materials.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A coated modified polystyrene pre-expanded particle, characterized in that: The invention comprises the following components in parts by weight: 70 to 80 parts of expandable graphite modified polystyrene particles, 8 to 10 parts of composite flame retardant, 2 to 4 parts of carbon nanofibers, 2 to 4 parts of nano silicon dioxide and 40 to 70 parts of coating agent; Wherein, the composite flame retardant comprises melamine, brucite, boric acid and organic modified montmorillonite base; The organic modified montmorillonite is a gemini quaternary ammonium salt modified montmorillonite; The structural formula of gemini quaternary ammonium salt is: 。 2. The coated modified polystyrene pre-expanded particles according to claim 1, characterized in that: The preparation method of the gemini quaternary ammonium salt comprises the following steps: adding tetramethylethylenediamine to an alcohol solution of 1-chloropentane, reacting at 58° C. to 62° C. for 11 h to 13 h, and obtaining the gemini quaternary ammonium salt.

3. The coated modified polystyrene pre-expanded particles according to claim 1 or 2, characterized in that: The preparation method of the gemini quaternary ammonium salt modified montmorillonite comprises the following steps: mixing a montmorillonite suspension with a gemini quaternary ammonium salt solution, reacting at 78° C. to 82° C. for 3 h to 4 h to obtain the gemini quaternary ammonium salt modified montmorillonite.

4. The coated modified polystyrene pre-expanded particles according to claim 1, characterized in that: The weight ratio of the melamine, brucite, boric acid and organic modified montmorillonite is 1:1.5-3:1-3:6-8.

5. The coated modified polystyrene pre-expanded particles according to claim 1 or 4, characterized in that: The particle size of the expandable graphite-modified polystyrene particles is 0.9 mm to 1.6 mm; and / or The magnesium hydroxide content (calculated as magnesium oxide) in the brucite is 60% to 70%.

6. The coated modified polystyrene pre-expanded particles according to claim 1, characterized in that: The coating agent includes at least two of silica sol, water glass or phenolic resin.

7. The method for preparing the coated modified polystyrene pre-expanded particles according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: Step 1, pre-expanding the expandable graphite-modified polystyrene particles to obtain initial pre-expanded particle material; The composite flame retardant, carbon nanofiber, nano silicon dioxide and coating agent are mixed to obtain coating slurry; Step 2, adding the coating slurry to the initial pre-fermented granular material to obtain coated granular material; Step 3: Ripening, drying and dispersing the coated particle material to obtain coated modified polystyrene pre-expanded particles.

8. The method for preparing coated modified polystyrene pre-expanded particles according to claim 7, characterized in that: The particle size of the initial pre-expanded granular material is 5 mm to 8 mm.

9. The method for preparing coated modified polystyrene pre-expanded particles according to claim 7, characterized in that: The aging temperature is 100° C. to 115° C., and the aging time is 3 min to 12 min.

10. Use of the coated modified polystyrene pre-expanded particles according to any one of claims 1 to 6 in the preparation of flame retardant boards.

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