Polystyrene foam containing carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules

Abstract

The application relates to the field of high polymer materials and discloses polystyrene foam plastic containing carbon nanotube / ferroferric oxide modified silica coated paraffin phase change microcapsules. The polystyrene foam plastic comprises the following components: 100-120 parts of polystyrene resin, 15-25 parts of carbon nanotube / ferroferric oxide modified silica coated paraffin phase change microcapsules, 2-6 parts of a foaming agent, 1-3 parts of a nucleating agent and 1-3 parts of a lubricant. In the application, the carbon nanotube / ferroferric oxide modified silica is used as a shell material to coat paraffin, and carbon nanotube / ferroferric oxide modified silica coated paraffin phase change microcapsules are synthesized. When the carbon nanotube / ferroferric oxide modified silica coated paraffin phase change microcapsules are added into the polystyrene foam plastic, the polystyrene foam plastic is endowed with excellent temperature adjusting function and flame retardant performance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, and more particularly to a polystyrene foam containing carbon nanotubes / ferric oxide modified silica-coated paraffin phase change microcapsules. Background Technology

[0002] Extruded polystyrene foam (EPS) possesses excellent properties such as light weight, low thermal conductivity, and shock absorption and noise reduction, leading to its widespread application in construction, packaging, automotive, and many other fields. Combining microcapsules with EPS can yield novel thermal insulation materials. For example, Chinese patent CN201711446852.3 discloses a method for preparing heat-storing EPS and its application, which improves the heat storage and temperature regulation capabilities of EPS by adding phase change microcapsules and uses it in helmets to improve comfort. However, the paraffin core material of phase change microcapsules is flammable. Adding it to flammable EPS further deteriorates its flame-retardant properties, making it difficult to meet the safety requirements of thermal insulation materials. Therefore, there is an urgent need to develop a phase change microcapsule with flame-retardant properties.

[0003] Kazanci et al. [Kazanci B, Cellat K, Paksoy H. Preparation, characterization, and thermal properties of novel fire-resistant microencapsulated phase change materials based on paraffin and a polystyrene shell[J]. RSC Adv, 2020, 10(40): 24134-24144.] added organophosphorus flame retardants to polystyrene-coated paraffin microcapsules through surface modification to improve the flame retardant properties of the microcapsules. However, the poor thermal conductivity of the polystyrene shell affects the heat storage and temperature regulation capabilities of the microcapsules. Therefore, it is necessary to develop a novel flame-retardant phase change microcapsule. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a polystyrene foam containing carbon nanotube / ferric oxide-modified silica-coated paraffin phase change microcapsules. The polystyrene foam of this invention contains carbon nanotube / ferric oxide-modified silica-coated paraffin phase change microcapsules. These microcapsules use carbon nanotube / ferric oxide-modified silica as the shell material to coat paraffin. This not only utilizes the high thermal conductivity of the ferric oxide nanoparticles and carbon nanotubes to achieve efficient temperature regulation of the phase change microcapsules, but also the synergistic effect of the ferric oxide nanoparticles, silica shell material, and carbon nanotubes promotes polymer carbonization and increases the carbon layer density, thereby achieving a highly efficient flame-retardant effect.

[0005] The specific technical solution of this invention is as follows:

[0006] In a first aspect, the present invention provides a polystyrene foam containing carbon nanotube / ferric oxide modified silica coated paraffin phase change microcapsules, comprising the following raw materials in parts by weight: 100-120 parts of polystyrene resin, 15-25 parts of carbon nanotube / ferric oxide modified silica coated paraffin phase change microcapsules, 2-6 parts of foaming agent, 1-3 parts of nucleating agent, and 1-3 parts of lubricant.

[0007] Preferably, the carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules use carbon nanotube / ferric oxide modified silica as the shell material and paraffin as the core material.

[0008] The polystyrene foam of the present invention contains carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules. The microcapsules use carbon nanotube / ferric oxide modified silica as the shell material to coat paraffin. This not only utilizes the high thermal conductivity of ferric oxide nanoparticles and carbon nanotubes to achieve efficient temperature regulation of the phase change microcapsules, but also the synergistic effect of ferric oxide nanoparticles, silica shell material and carbon nanotubes (wherein carbon nanotubes and silica shell material act as flame retardants, while ferric oxide nanoparticles act as carbonization catalysts, promoting the self-carbonization of polymers during combustion) promotes polymer carbonization and increases char layer density, thereby achieving a highly efficient flame retardant effect.

[0009] Preferably, the foaming agent is a BSH foaming agent, an OBSH foaming agent, or a DPT foaming agent; the nucleating agent is talc or sodium bicarbonate; and the lubricant is glyceryl monostearate or stearamide.

[0010] Secondly, the present invention also provides a method for preparing polystyrene foam plastic containing carbon nanotube / ferric oxide modified silica coated with paraffin phase change microcapsules, comprising the following steps:

[0011] (1) Paraffin wax and tetraethyl orthosilicate were mixed and heated and stirred. After the paraffin wax melted, a formamide solution containing hexadecyltrimethylammonium bromide was added dropwise. The mixture was heated and stirred to form a microemulsion. Hydrochloric acid solution was added dropwise to carry out the reaction. Then the stirring was stopped and the mixture was kept warm and allowed to stand. After the reaction was completed, the product was centrifuged, washed and dried to obtain silica-coated paraffin wax microcapsules.

[0012] (2) The silica-coated paraffin microcapsules obtained in step (1) were added to water and ultrasonically dispersed and mixed evenly. A mixed solution of FeCl3·6H2O and FeCl2·4H2O was added dropwise under heating and stirring conditions, followed by ammonia water. The mixture was kept warm and stirred. After the reaction was completed, the product was centrifuged and washed to obtain ferric oxide-modified silica-coated paraffin microcapsules.

[0013] (3) The paraffin microcapsules coated with iron oxide modified silica obtained in step (2) are mixed with anhydrous ethanol and heated and stirred until uniform to obtain a mixture; 3-aminopropyltriethoxysilane (KH-550) is added to water and stirred, and then the resulting reaction solution is added dropwise to the mixture to continue the reaction to obtain an aminated iron oxide modified silica coated paraffin microcapsule solution.

[0014] (4) Add the anhydrous ethanol dispersion containing carboxylated carbon nanotubes to the solution obtained in step (3), and add an aqueous solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) under stirring conditions to react. The resulting product is washed, centrifuged and dried to obtain carbon nanotube / iron oxide modified silica-coated paraffin phase change microcapsules.

[0015] (5) The carbon nanotubes / iron oxide modified silica coated with paraffin phase change microcapsules, nucleating agent, polystyrene resin, lubricant and foaming agent obtained in step (4) are processed into polystyrene foam plastic by a single screw extruder.

[0016] The preparation principle of the carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules of the present invention is as follows: In step (1), the melted paraffin is the oil phase, tetraethyl orthosilicate is the aqueous phase, formamide is the reaction solvent, and hexadecyltrimethylammonium bromide is the emulsifier. Its hydrophilic end is affinity for tetraethyl orthosilicate, and its lipophilic end is inserted into the paraffin droplets, forming a micelle system on the surface of the oil droplets. A stable emulsion is formed by stirring and emulsifying. When hydrochloric acid is slowly added dropwise, tetraethyl orthosilicate hydrolyzes and condenses on the surface of the paraffin droplets to form silica. In step (2), iron ions are aggregated on the surface of silica by electrostatic attraction and in-situ precipitation. Then, ammonia is added to the reaction system, and dispersed ferric oxide nanoparticles are grown in situ on the surface of silica. The reaction mechanism is as follows:

[0017] Fe 2+ +Fe 3+ +8OH - →Fe(OH)2+2Fe(OH)3→Fe3O4+4H2O

[0018] Based on this, in step (3), 3-aminopropyltriethoxysilane is used to modify the surface of the iron oxide nanoparticles and the silica shell. The iron oxide nanoparticles have a large number of hydroxyl groups on their surface, which react with the silanol bonds generated by the hydrolysis of 3-aminopropyltriethoxysilane to form hydrogen bonds and condense. At the same time, the silanol bonds self-condense and coat the surface of the iron oxide nanoparticles, thereby obtaining amino-modified microcapsules. Subsequently, in step (4), after adding uniformly dispersed carboxylated carbon nanotubes, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is added. It first reacts with the carboxyl groups on the carbon nanotubes to form an amine-reactive O-acyl isourea intermediate. This intermediate can react rapidly with the amino groups on the microcapsules to form amide bonds, finally obtaining carbon nanotube / iron oxide modified silica-coated paraffin phase change microcapsules.

[0019] Preferably, in step (1), the ratio of the amount of paraffin, tetraethyl orthosilicate, hexadecyltrimethylammonium bromide, formamide and hydrochloric acid solution is 5-7g: 5-7g: 0.75-1.5g: 100-150ml: 100-150ml.

[0020] Preferably, in step (1), the concentration of the hydrochloric acid solution is 0.8-1.2 mol / L.

[0021] Preferably, in step (1), the paraffin is a single-melting-point paraffin or a mixed paraffin composed of multiple single-melting-point paraffins, with a melting point of 28-50℃.

[0022] Preferably, in step (1), the heating temperature is 50-55℃, the stirring speed is 500-1000rpm, and the time is 30-60min; after adding hydrochloric acid solution, the reaction time is 4-6h, the standing time is 12-24h, the centrifugation speed is 4000-8000rpm, and the centrifugation time is 5-15min; the washing method is to wash with deionized water 2-4 times and anhydrous ethanol 2-4 times; the drying conditions are 55-65℃ for 24-48h.

[0023] Preferably, in step (2), the ratio of the amount of silica-coated paraffin microcapsules, water, the mixed solution of FeCl3·6H2O and FeCl2·4H2O, and ammonia is 0.5-0.75g: 40-60ml: 10-15ml: 4-8ml.

[0024] In step (2), the amount of the mixed solution of FeCl3·6H2O and FeCl2·4H2O affects the amount of iron(III) oxide generated in situ on the surface of the microcapsules. When the amount of the mixed solution of FeCl3·6H2O and FeCl2·4H2O is too small, the amount of iron(III) oxide nanoparticles generated in situ is small, making it difficult to promote the carbonization of the polymer during combustion. On the other hand, when the amount of the mixed solution is too large, the particle size of iron(III) oxide increases rapidly, thereby reducing its catalytic carbonization activity of the polymer. If the amount of ammonia water is too small, the reaction will be incomplete, resulting in the formation of impurities such as ferric oxide.

[0025] Preferably, in step (2), the concentration of FeCl3·6H2O in the mixed solution is 0.001-0.002 mol / ml, and the concentration of FeCl2·4H2O is 0.003-0.004 mol / ml.

[0026] Preferably, in step (2), the concentration of the ammonia water is 25-28 wt%.

[0027] Preferably, in step (2), the ultrasonic dispersion temperature is 40-60℃ and the time is 30-50 min; the heating and stirring speed is 500-800 rpm and the temperature is 70-80℃; the stirring time after adding the FeCl3·6H2O and FeCl2·4H2O mixed solution is 15-30 min; the ammonia water dropping rate is 0.25-0.5 ml / min and the stirring time after adding ammonia water is 10-30 min; the centrifugation speed is 4000-5000 rpm and the centrifugation time is 5-8 min; the washing method is washing with deionized water 2-4 times and washing with anhydrous ethanol 2-4 times; the drying conditions are 55-65℃ for 24-48 h.

[0028] Preferably, in step (3), the ratio of the amount of iron oxide-modified silica-coated paraffin microcapsules, anhydrous ethanol, 3-aminopropyltriethoxysilane and water is 0.5-0.75g: 80-100ml: 2-5ml: 0.5-1.5ml.

[0029] In step (3), the ratio of 3-aminopropyltriethoxysilane to water affects its hydrolysis-condensation reaction rate. Adding water hydrolyzes 3-aminopropyltriethoxysilane, and the resulting silanol bonds form hydrogen bonds with the hydroxyl groups on the microcapsule surface, followed by dehydration and condensation, thus modifying the microcapsule surface with amination. If the water content is too high, it will intensify the self-condensation between the silanol bonds in the hydrolysis products, thereby reducing the amination effect on the microcapsule surface. If the water content is too low, it will lead to incomplete hydrolysis of 3-aminopropyltriethoxysilane, also reducing the surface modification effect of the microcapsule.

[0030] Preferably, in step (3), the heating and stirring temperature is 35-45℃, the stirring speed is 500-700rpm, the time is 10-30min, and the reaction time is 18-24h.

[0031] Preferably, in step (4), the ratio of the amino-modified iron tetroxide-modified silica-coated paraffin microcapsule solution, carboxylated carbon nanotubes, anhydrous ethanol, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride aqueous solution is 40-80 ml: 0.05-0.075 g: 40-80 ml: 0.5-1 ml.

[0032] Preferably, in step (4), the concentration of the aqueous solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is 0.008-0.012 g / mL.

[0033] As a preferred embodiment, in step (4), the reaction time is 20-24h; the centrifugation speed is 4000-5000rpm and the centrifugation time is 10-15min; the washing method is to wash with deionized water 2-4 times and anhydrous ethanol 2-4 times; the drying conditions are 45-55℃ for 24-48h.

[0034] Preferably, step (5) specifically includes: adding the carbon nanotube / iron oxide modified silica-coated paraffin phase change microcapsules, nucleating agent, polystyrene resin, and lubricant obtained in step (4) to a No. 1 single-screw extruder for mixing and stirring. After being uniformly plasticized at high temperature in the compression section and homogenization section, a foaming agent is injected, and the mixture is initially mixed and homogenized in the mixing section. The resulting molten material is further fully mixed and cooled in a No. 2 single-screw extruder, and then transferred to a mold. After being shaped by a leveling machine, polystyrene foam is obtained after secondary processing and cooling.

[0035] Preferably, in step (5), the screw of the No. 1 single-screw extruder is divided into four zones, with the temperature of zone 1 set to 165-175℃, zone 2 set to 175-185℃, zone 3 set to 185-195℃, and zone 4 set to 195-205℃; the high-temperature screw of the No. 2 single-screw extruder is divided into four zones, with the temperature of zone 1 set to 195-205℃, zone 2 set to 195-205℃, zone 3 set to 175-185℃, and zone 4 set to 145-155℃.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] (1) This invention uses carbon nanotubes / ferric oxide modified silica as the shell material and coats it with paraffin to synthesize carbon nanotubes / ferric oxide modified silica coated with paraffin phase change microcapsules. It not only utilizes the high thermal conductivity of ferric oxide nanoparticles and carbon nanotubes to achieve efficient heat storage and temperature regulation of phase change microcapsules, but also the synergistic effect of ferric oxide nanoparticles, silica and carbon nanotubes promotes polymer carbonization and increases carbon layer density to achieve efficient flame retardant effect.

[0038] (2) In this invention, carbon nanotubes / iron oxide modified silica coated paraffin phase change microcapsules with flame retardant and temperature regulating functions are added to extruded polystyrene foam to form a composite material. This not only improves the thermal conductivity of the composite material by utilizing the high thermal conductivity of carbon nanotubes and iron oxide, thus giving the extruded polystyrene foam an efficient temperature regulating function, but also greatly improves the flame retardant properties of the extruded polystyrene foam. Attached Figure Description

[0039] Figure 1 This is a schematic diagram illustrating the preparation principle of carbon nanotube / iron tetroxide modified silica-coated paraffin phase change microcapsules in Example 1;

[0040] Figure 2 The images show the FT-IR spectra of the paraffin-coated paraffin phase change microcapsules and the carbon nanotube / ferric oxide-modified silica-coated paraffin phase change microcapsules in Example 1.

[0041] Figure 3 The image shows the XRD pattern of the carbon nanotube / iron tetroxide modified silica-coated paraffin phase change microcapsules in Example 1.

[0042] Figure 4 SEM image of silica-coated paraffin phase change microcapsules in Example 1;

[0043] Figure 5 SEM image of the carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules in Example 1;

[0044] Figure 6 The bar chart shows the thermal conductivity of paraffin and carbon nanotube / iron oxide modified silica-coated paraffin phase change microcapsules in Example 1.

[0045] Figure 7 The time-temperature curves for paraffin phase transition microcapsules and carbon nanotube / ferric oxide modified silica-coated paraffin microcapsules from Example 1 are shown. Detailed Implementation

[0046] The present invention will be further described below with reference to embodiments.

[0047] General Implementation Examples

[0048] A polystyrene foam containing carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules, comprising the following raw materials in parts by weight: 100-120 parts polystyrene resin, 15-25 parts carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules, 2-6 parts foaming agent, 1-3 parts nucleating agent, and 1-3 parts lubricant.

[0049] Preferably, the foaming agent is a BSH foaming agent, an OBSH foaming agent, or a DPT foaming agent; the nucleating agent is talc or sodium bicarbonate; and the lubricant is glyceryl monostearate or stearamide.

[0050] A method for preparing polystyrene foam containing carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules, the preparation mechanism of which is as follows: Figure 1 As shown, the specific steps include:

[0051] (1) Place 5-7g of paraffin wax (melting point 28-50℃, the paraffin wax is a single melting point paraffin wax or a mixed paraffin wax composed of multiple single melting point paraffin waxes) and 5-7g of tetraethyl orthosilicate into a three-necked flask and heat to 50-55℃. Stir mechanically at 500-1000rpm. After the paraffin wax melts, add 100-150ml of formamide solution containing 0.75-1.5g of cetyltrimethylammonium bromide. Continue heating and stirring for 30-60min to form a microemulsion. Then slowly add 100-150ml of 1mol / L hydrochloric acid solution. React for 4-6h, then stop stirring and keep warm for 12-24h. After the reaction is complete, take out the product and centrifuge at 4000-8000rpm for 5-15min. Wash the precipitate 2-4 times with deionized water and ethanol respectively, and dry in a drying oven at 55-65℃ for 24-48h to obtain silica-coated paraffin microcapsules.

[0052] (2) Take 0.5-0.75g of silica-coated paraffin microcapsules prepared in step (1) and add 40-60ml of distilled water. Disperse the mixture by ultrasonication at 40-60℃ for 30-50min until homogeneous. Then place it in a three-necked flask and heat it to 70-80℃. Stir mechanically at 500-800rpm. Add 10-15ml of a mixed solution of FeCl3·6H2O (0.0015mol / L) and FeCl2·4H2O (0.003675mol / L) dropwise into the three-necked flask and stir for 15-30min. Then slowly add 4-8ml of concentrated ammonia (25-28wt%) at a rate of 0.25-0.5ml / min and stir at the same rate and temperature for 10-30min. After the reaction was completed, the solution was removed and centrifuged at 4000-5000 rpm to obtain the precipitate. The precipitate was washed 2-4 times with deionized water and ethanol, respectively, and then dried in a drying oven at 55-65℃ for 24-48 hours to obtain paraffin microcapsules coated with ferric oxide-modified silica.

[0053] (3) Take 0.5-0.75g of the iron oxide-modified silica-coated paraffin microcapsules obtained in step (2) and place them in a three-necked flask. Add 80-100ml of anhydrous ethanol and heat to 40℃. Disperse the mixture by mechanical stirring at 500-700rpm. Take 2-5ml of 3-aminopropyltriethoxysilane (KH-550) and place it in a beaker. Add 1-1.5ml of distilled water and stir magnetically for 10-30min. Then add it dropwise to the three-necked flask and continue the reaction for 18-24h to obtain an aminated iron oxide-modified silica-coated paraffin microcapsule solution.

[0054] (4) Take 0.05-0.075g of carboxylated carbon nanotubes and place them in a beaker. Add 40-80ml of anhydrous ethanol and sonicate for 1-2h. Then add the mixture to 80-100ml of the solution obtained in step (3). Under continuous mechanical stirring at 800-1000rpm at 55-65℃, add 1-10ml of aqueous solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) (0.01g / ml) and continue stirring for 20-24h. Centrifuge at 4000-5000rpm for 10-15min to obtain the precipitate. Wash the precipitate with deionized water and anhydrous ethanol 2-4 times, and then dry it in a drying oven at 45-55℃ for 24-48h to obtain carbon nanotube / iron oxide modified silica-coated paraffin phase change microcapsules.

[0055] (5) The carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules, nucleating agent, polystyrene resin, lubricant, and other raw materials obtained in step (4) are stored independently according to their components. They are fed and mixed in a No. 1 single-screw extruder through an automatic control system. After being uniformly plasticized at high temperature in the compression and homogenization sections, the foaming agent is injected and preliminarily mixed and homogenized in the mixing section. In a No. 2 single-screw extruder, the molten material and foaming agent are further fully mixed and cooled. Then, the temperature is precisely controlled by a heat exchanger and added to the mold. After being shaped by a leveling machine, polystyrene foam with flame-retardant and temperature-regulating functions is obtained after secondary processing and cooling. The screw of the No. 1 single-screw extruder is divided into four zones: zone 1 temperature is set at 165-175℃, zone 2 temperature at 175-185℃, zone 3 temperature at 185-195℃, and zone 4 temperature at 195-205℃. The high-temperature screw of the No. 2 single-screw extruder is also divided into four zones: zone 1 temperature at 195-205℃, zone 2 temperature at 195-205℃, zone 3 temperature at 175-185℃, and zone 4 temperature at 145-155℃.

[0056] Example 1

[0057] (1) 5g of paraffin wax (melting point 28-30℃) and 5g of tetraethyl orthosilicate were placed in a three-necked flask and heated to 50℃ with mechanical stirring at 600rpm. After the paraffin wax melted, 100ml of formamide solution containing 0.75% hexadecyltrimethylammonium bromide was added dropwise, and the mixture was heated and stirred for 40min to form a microemulsion. Then, 100ml of 1mol / L hydrochloric acid solution was slowly added dropwise. The reaction was allowed to proceed for 4h, and then stirring was stopped and the mixture was kept at this temperature for 18h. After the reaction was completed, the product was taken out and centrifuged at 5000rpm for 5min. The precipitate was washed three times with deionized water and ethanol, respectively, and then dried in a drying oven at 55℃ for 48h to obtain silica-coated paraffin wax microcapsules.

[0058] (2) Take 0.5 g of the silica-coated paraffin microcapsules obtained in step (1) and add 40 ml of distilled water. Disperse the mixture ultrasonically at 40 °C for 50 min until homogeneous. Then, place the mixture in a three-necked flask and heat it to 80 °C while mechanically stirring at 500 rpm. Add 10 ml of a mixed solution of FeCl3·6H2O (0.0015 mol / L) and FeCl2·4H2O (0.003675 mol / L) dropwise to the three-necked flask and stir for 15 min. Then, slowly add 5 ml of concentrated ammonia (28 wt%) at a rate of 0.25 ml / min and stir at the same rate and temperature for 30 min. After the reaction is complete, remove the solution and centrifuge at 4000 rpm to obtain the precipitate. Wash the precipitate three times with deionized water and ethanol, respectively, by centrifugation. Dry the precipitate in a drying oven at 55 °C for 48 h to obtain the iron tetroxide-modified silica-coated paraffin microcapsules.

[0059] (3) Take 0.5g of the iron oxide-modified silica-coated paraffin microcapsules obtained in step (2) and place them in a three-necked flask. Add 80ml of anhydrous ethanol and heat to 40℃. Disperse the mixture by mechanical stirring at 500rpm. Take 2ml of 3-aminopropyltriethoxysilane (KH-550) and place it in a beaker. Add 1ml of distilled water and stir magnetically for 30min. Then add it dropwise to the three-necked flask and continue the reaction for 18h to obtain an aminated iron oxide-modified silica-coated paraffin microcapsule solution.

[0060] (4) Take 0.05 g of carboxylated carbon nanotubes and place them in a beaker. Add 40 ml of anhydrous ethanol and sonicate for 1 h. Then add the mixture to 80 ml of the solution obtained in step (3). Under continuous mechanical stirring at 800 rpm at 55 °C, add 1 ml of aqueous solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) (0.01 g / ml) and continue stirring for 24 h. Centrifuge at 4000 rpm for 10 min to obtain the precipitate. Wash the precipitate three times with deionized water and anhydrous ethanol, respectively, and centrifuge three times. Dry the precipitate at 55 °C for 48 h in a drying oven to obtain carbon nanotube / iron oxide modified silica-coated paraffin phase change microcapsules.

[0061] (5) The carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules, nucleating agent, polystyrene resin, lubricant, and other raw materials obtained in step (4) are stored independently according to their components. They are fed and mixed in a No. 1 single-screw extruder through an automatic control system. After being uniformly plasticized at high temperature in the compression and homogenization sections, the foaming agent is injected and preliminarily mixed and homogenized in the mixing section. In a No. 2 single-screw extruder, the molten material and foaming agent are further fully mixed and cooled. Then, the temperature is precisely controlled by a heat exchanger and added to the mold. After being shaped by a leveling machine, polystyrene foam with flame-retardant and temperature-regulating functions is obtained after secondary processing and cooling. The No. 1 single-screw extruder has a 15-meter-long high-temperature screw divided into four zones: Zone 1 temperature is set at 170℃, Zone 2 at 180℃, Zone 3 at 190℃, and Zone 4 at 200℃. The No. 2 single-screw extruder has a 10-meter-long high-temperature screw divided into four zones: Zone 1 temperature is set at 200℃, Zone 2 at 200℃, Zone 3 at 180℃, and Zone 4 at 150℃. The raw materials are as follows (parts by weight): polystyrene resin 100 parts; carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules 25 parts; OBSH foaming agent 4 parts; talc 1 part; glyceryl monostearate 1 part.

[0062] Example 2

[0063] (1) 6g of paraffin (melting point 48-50℃) and 6g of tetraethyl orthosilicate were placed in a three-necked flask and heated to 55℃ with mechanical stirring at 1000rpm. After the paraffin melted, 125ml of formamide solution containing 1g of hexadecyltrimethylammonium bromide was added dropwise. The mixture was heated and stirred for 60min to form a microemulsion. Then, 125ml of 1mol / L hydrochloric acid solution was slowly added dropwise. The reaction was allowed to proceed for 6h, and then stirring was stopped and the mixture was kept at this temperature for 24h. After the reaction was completed, the product was taken out and centrifuged at 8000rpm for 5min. The precipitate was washed three times with deionized water and ethanol, respectively, and then dried in a drying oven at 65℃ for 48h to obtain silica-coated paraffin microcapsules.

[0064] (2) Take 0.5 g of the silica-coated paraffin microcapsules obtained in step (1) and add 50 ml of distilled water. Disperse the mixture ultrasonically at 40 °C for 50 min until homogeneous. Then, place the mixture in a three-necked flask and heat it to 80 °C while mechanically stirring at 600 rpm. Add 12.5 ml of a mixed solution of FeCl3·6H2O (0.0015 mol / L) and FeCl2·4H2O (0.003675 mol / L) dropwise to the three-necked flask and stir for 15 min. Then, slowly add 6 ml of concentrated ammonia (28 wt%) at a rate of 0.25 ml / min and stir at the same rate and temperature for 30 min. After the reaction is complete, remove the solution and centrifuge at 5000 rpm to obtain the precipitate. Wash the precipitate three times with deionized water and ethanol, respectively, by centrifugation. Dry the precipitate in a drying oven at 65 °C for 48 h to obtain the iron tetroxide-modified silica-coated paraffin microcapsules.

[0065] (3) Take 0.5g of the iron oxide-modified silica-coated paraffin microcapsules obtained in step (2) and place them in a three-necked flask. Add 90ml of anhydrous ethanol and heat to 40℃. Disperse the mixture by mechanical stirring at 700rpm. Take 4ml of 3-aminopropyltriethoxysilane (KH-550) and place it in a beaker. Add 1ml of distilled water and stir magnetically for 30min. Then add it dropwise to the three-necked flask and continue the reaction for 24h to obtain an aminated iron oxide-modified silica-coated paraffin microcapsule solution.

[0066] (4) Take 0.05 g of carboxylated carbon nanotubes and place them in a beaker. Add 40 ml of anhydrous ethanol and sonicate for 2 h. Then add the mixture to 90 ml of the solution obtained in step (3). Under continuous mechanical stirring at 1000 rpm at 65 °C, add 2 ml of aqueous solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) (0.01 g / ml) and continue stirring for 24 h. Centrifuge at 5000 rpm for 15 min to obtain the precipitate. Wash the precipitate three times with deionized water and anhydrous ethanol, respectively, and centrifuge three times. Dry the precipitate at 55 °C for 48 h in a drying oven to obtain carbon nanotube / iron oxide modified silica-coated paraffin phase change microcapsules.

[0067] (5) The carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules, nucleating agent, polystyrene resin, lubricant, and other raw materials obtained in step (4) are stored independently according to their components. They are fed and mixed in a No. 1 single-screw extruder through an automatic control system. After being uniformly plasticized at high temperature in the compression and homogenization sections, the foaming agent is injected and preliminarily mixed and homogenized in the mixing section. In a No. 2 single-screw extruder, the molten material and foaming agent are further fully mixed and cooled. Then, the temperature is precisely controlled by a heat exchanger and added to the mold. After being shaped by a leveling machine, polystyrene foam with flame-retardant and temperature-regulating functions is obtained after secondary processing and cooling. The No. 1 single-screw extruder has a 15-meter-long high-temperature screw divided into four zones: Zone 1 temperature is set at 170℃, Zone 2 at 180℃, Zone 3 at 190℃, and Zone 4 at 200℃. The No. 2 single-screw extruder has a 10-meter-long high-temperature screw divided into four zones: Zone 1 temperature is set at 200℃, Zone 2 at 200℃, Zone 3 at 180℃, and Zone 4 at 150℃. The raw materials are as follows (parts by weight): polystyrene resin 110 parts; carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules 20 parts; OBSH foaming agent 4 parts; talc 2 parts; glyceryl monostearate 2 parts.

[0068] Example 3

[0069] (1) 7g of paraffin (melting point 48-50℃) and 7g of tetraethyl orthosilicate were placed in a three-necked flask and heated to 55℃ with mechanical stirring at 1000rpm. After the paraffin melted, 150ml of formamide solution containing 1.5g of hexadecyltrimethylammonium bromide was added dropwise, and the mixture was heated and stirred for 60min to form a microemulsion. Then, 150ml of 1mol / L hydrochloric acid solution was slowly added dropwise. The reaction was allowed to proceed for 6h, and then stirring was stopped and the mixture was kept at this temperature for 24h. After the reaction was completed, the product was taken out and centrifuged at 8000rpm for 15min. The precipitate was washed three times with deionized water and ethanol, respectively, and then dried in a drying oven at 65℃ for 48h to obtain silica-coated paraffin microcapsules.

[0070] (2) Take 0.75 g of the silica-coated paraffin microcapsules obtained in step (1) and add 60 ml of distilled water. Disperse the mixture ultrasonically at 40 °C for 50 min until homogeneous. Then, place the mixture in a three-necked flask and heat it to 80 °C while mechanically stirring at 800 rpm. Add 15 ml of a mixed solution of FeCl3·6H2O (0.0015 mol / L) and FeCl2·4H2O (0.003675 mol / L) dropwise to the three-necked flask and stir for 30 min. Then, slowly add 8 ml of concentrated ammonia (28 wt%) at a rate of 0.5 ml / min and stir at the same rate and temperature for 20 min. After the reaction is complete, remove the solution and centrifuge at 5000 rpm to obtain the precipitate. Wash the precipitate three times with deionized water and ethanol, respectively, by centrifugation. Dry the precipitate in a drying oven at 65 °C for 48 h to obtain the iron oxide-modified silica-coated paraffin microcapsules.

[0071] (3) Take 0.75 g of the iron oxide-modified silica-coated paraffin microcapsules obtained in step (2) and place them in a three-necked flask. Add 100 ml of anhydrous ethanol and heat to 40 °C. Disperse the mixture by mechanical stirring at 700 rpm. Take 5 ml of 3-aminopropyltriethoxysilane (KH-550) and place it in a beaker. Add 1.5 ml of distilled water and stir magnetically for 30 min. Then add it dropwise to the three-necked flask and continue the reaction for 24 h to obtain an aminated iron oxide-modified silica-coated paraffin microcapsule solution.

[0072] (4) Take 0.075 g of carboxylated carbon nanotubes and place them in a beaker. Add 60 ml of anhydrous ethanol and sonicate for 2 h. Then add the mixture to 100 ml of the solution obtained in step (3). Under continuous mechanical stirring at 1000 rpm at 65 °C, add 3 ml of aqueous solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) (0.01 g / ml) and continue stirring for 24 h. Centrifuge at 5000 rpm for 15 min to obtain the precipitate. Wash the precipitate three times with deionized water and anhydrous ethanol, respectively, and centrifuge three times. Dry the precipitate at 55 °C for 48 h in a drying oven to obtain carbon nanotube / iron oxide modified silica-coated paraffin phase change microcapsules.

[0073] (5) The carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules, nucleating agent, polystyrene resin, lubricant, and other raw materials obtained in step (4) are stored independently according to their components. They are fed and mixed in a No. 1 single-screw extruder through an automatic control system. After being uniformly plasticized at high temperature in the compression and homogenization sections, the foaming agent is injected and preliminarily mixed and homogenized in the mixing section. In a No. 2 single-screw extruder, the molten material and foaming agent are further fully mixed and cooled. Then, the temperature is precisely controlled by a heat exchanger and added to the mold. After being shaped by a leveling machine, polystyrene foam with flame-retardant and temperature-regulating functions is obtained after secondary processing and cooling. The No. 1 single-screw extruder has a 15-meter-long high-temperature screw divided into four zones: Zone 1 temperature is set at 170℃, Zone 2 at 180℃, Zone 3 at 190℃, and Zone 4 at 200℃. The No. 2 single-screw extruder has a 10-meter-long high-temperature screw divided into four zones: Zone 1 temperature is set at 200℃, Zone 2 at 200℃, Zone 3 at 180℃, and Zone 4 at 150℃. The raw materials are distributed as follows: 120 parts polystyrene resin; 15 parts carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules; 6 parts OBSH foaming agent; 3 parts talc; and 3 parts glyceryl monostearate.

[0074] Performance Testing and Characterization: The following are experimental data from Example 1:

[0075] Figure 2 The figures show the infrared spectra of silica-coated paraffin, magnetite-modified silica-coated paraffin, and carbon nanotube / magnetite-modified silica-coated paraffin phase transition microcapsules, respectively. As can be seen from the figures, the 2853 cm⁻¹ in the infrared spectrum of the silica-coated paraffin microcapsules... -1 and 2918cm -1 The absorption peaks at 1394 cm⁻¹ correspond to the symmetric stretching vibration peak and the asymmetric stretching vibration peak of the CH bond in the chemical structure of paraffin, respectively. -1 The absorption peak at 1080 cm⁻¹ corresponds to the bending vibration peak of the CH bond. -1 There is an asymmetric tensile vibration peak in Si-O-Si at 463 cm⁻¹. -1 The peak at 578 cm⁻¹ is the bending vibration peak of Si-O-Si. In the infrared spectra of iron(III) oxide / silica-coated paraffin and carbon nanotube / iron(III) oxide-modified silica-coated paraffin phase change microcapsules, in addition to the infrared absorption peaks of paraffin and silica, a peak at 578 cm⁻¹ can be observed. -1 There is a relatively small absorption peak, which is the characteristic absorption peak of Fe-O.

[0076] Figure 3XRD patterns of paraffin phase transition microcapsules coated with silica and modified with carbon nanotubes / ferric oxide. As shown in the figure, diffraction angles 2θ of 22.01° and 24.17° correspond to the (110) and (0014) crystal planes of paraffin, respectively (JCPDF 361591). Diffraction angles 2θ of 31.13°, 35.39°, 37.12°, 43.05°, 57.01° and 62.58° correspond to the (220), (311), (222), (400), (511) and (440) crystal planes of Fe3O4 (JCPDF 19-0629). Diffraction angle 2θ of 25.94° corresponds to the characteristic peak of the (002) crystal plane of carbon nanotube (JCPDS41-1487). No obvious diffraction peaks of silica are seen in the figure. This is mainly due to the overlap between the amorphous peak of silica at around 23°C and the diffraction peaks of paraffin.

[0077] Figure 4 This is a SEM image of silica-coated paraffin phase change microcapsules. Figure 4 As shown, the microcapsules have a smooth and dense surface with a particle size of about 1 to 3 μm. The silica shell is coated with paraffin to prevent leakage of the phase change material paraffin during the phase change process.

[0078] Figure 5 The figure shows that carbon nanotubes / ferric oxide modified silica-coated paraffin phase change microcapsules are produced. As can be seen from the figure, ferric oxide nanoparticles are dispersed on the surface of the microcapsules, while carbon nanotubes are wrapped around the surface of the microcapsules in a network structure.

[0079] Figure 6 The bar chart shows the thermal conductivity of solid paraffin (melting point 28-30℃) and carbon nanotube / ferric oxide-modified silica-coated paraffin phase change microcapsules. The thermal conductivity of solid paraffin (melting point 28-30℃) and carbon nanotube / ferric oxide-modified silica-coated paraffin phase change microcapsules is 0.1511 W·m. -1 K -1 and 0.6530 W·m -1 K -1 Compared with paraffin, the thermal conductivity of carbon nanotube / iron tetroxide modified silica-coated paraffin phase change microcapsules was increased by 332.16%.

[0080] Figure 7The figure shows the time-temperature relationship curves for the same mass of pure paraffin and carbon nanotube / ferric oxide-modified silica-coated paraffin phase change microcapsules. As can be seen from the figure, after the onset of light exposure, the temperature of both samples rapidly rises to approximately 28°C, with the carbon nanotube / ferric oxide-modified silica-coated paraffin phase change microcapsules showing a faster temperature rise. This is because the melting point of the phase change material is approximately 28°C; before 28°C, the phase change material does not undergo a phase change to absorb heat. The different temperature rise rates of the two samples are due to the different thermal conductivity of the two materials; the thermal conductivity of the carbon nanotube / ferric oxide-modified silica-coated paraffin phase change microcapsules is higher than that of paraffin. In the second part, after the temperature of both samples reached 28℃, the temperature rose very slowly for a period of time. During this stage, paraffin underwent a phase transition, changing from solid to liquid. During the phase transition, a certain amount of heat was absorbed. Since all of this heat was absorbed by the paraffin, for samples of the same mass, the paraffin sample showed a slower temperature rise for a longer period than the carbon nanotube / iron oxide modified silica-encapsulated paraffin phase transition microcapsules. In the third part, the temperature of both samples began to rise gradually again until the ambient temperature. The heat absorption of both samples had reached saturation, and the temperature continued to rise with the duration of light exposure.

[0081] Table 1 shows the flame retardant properties of pure extruded polystyrene foam and extruded polystyrene foam with carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules.

[0082] Table 1

[0083] <![CDATA[t1+t2(S)]]> LOI (%) Extruded polystyrene foam - 17.8 Example 1 17.2 24.6 Example 2 21.8 23.9 Example 3 25.7 23.1

[0084] In the table, t1 and t2 represent the average burning time of the specimen after the first and second ignition in the vertical burning test, respectively, and LOI% represents the limiting oxygen index of the material. As shown in Table 1, extruded polystyrene foam without phase change microcapsules did not exhibit self-extinguishing behavior in the vertical burning test. However, all examples using carbon nanotube / ferric oxide modified silica-coated paraffin phase change microcapsules as fillers exhibited self-extinguishing properties, with Example 1 showing the shortest burning time and the best self-extinguishing ability. Furthermore, compared to extruded polystyrene foam without phase change microcapsules, the limiting oxygen index of extruded polystyrene foam with added microcapsules was improved, with Example 1 showing the highest oxygen index. The results indicate that the addition of microcapsules significantly improves the flame retardant properties of polystyrene foam, and the flame retardant properties increase with the increase of the microcapsule proportion.

[0085] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A polystyrene foam plastic containing carbon nanotube / ferroferric oxide modified silica-coated paraffin phase change microcapsules, characterized by: The raw materials include the following mass fractions: polystyrene resin 100-120 parts, carbon nanotube / ferroferric oxide modified silica coated paraffin phase change microcapsule 15-25 parts, foaming agent 2-6 parts, nucleating agent 1-3 parts, lubricant 1-3 parts. The carbon nanotube / ferroferric oxide modified silica coated paraffin phase change microcapsule has carbon nanotube / ferroferric oxide modified silica as a shell material and paraffin as a core material; ferroferric oxide is in-situ grown in a dispersed distribution manner on the surface of silica, and carbon nanotube is grafted on the surface of ferroferric oxide.

2. The polystyrene foam plastic according to claim 1, characterized in that: the foaming agent is BSH foaming agent, OBSH foaming agent or DPT foaming agent; the nucleating agent is talc or sodium bicarbonate; the lubricant is glycerol monostearate or stearic acid amide.

3. A method for preparing polystyrene foam containing carbon nanotube / ferroferric oxide modified silica-coated paraffin phase change microcapsules according to claim 1 or 2, characterized by The method includes the following steps: (1) mixing and heating paraffin and tetraethyl orthosilicate, and then adding a formamide solution containing hexadecyl trimethyl ammonium bromide dropwise after the paraffin is melted, to form a microemulsion, and then adding a hydrochloric acid solution dropwise to react, and then stopping stirring and keeping warm to stand, and then centrifuging, washing and drying the obtained product to obtain silica coated paraffin microcapsule; (2) adding the silica coated paraffin microcapsule obtained in step (1) into water and ultrasonically dispersing to mix uniformly, and then adding a mixed solution of FeCl3·6H2O and FeCl2·4H2O dropwise under heating and stirring, and then adding ammonia water dropwise, and keeping warm and stirring; after the reaction is completed, centrifuging and washing the obtained product to obtain ferroferric oxide modified silica coated paraffin microcapsule; (3) mixing the ferroferric oxide modified silica coated paraffin microcapsule obtained in step (2) with anhydrous ethanol and heating and stirring to obtain a mixed solution; adding 3-aminopropyl triethoxysilane into water and stirring, and then adding the obtained reaction solution into the mixed solution to continue the reaction to obtain a solution of amino-modified ferroferric oxide modified silica coated paraffin microcapsule; (4) adding a carboxylated carbon nanotube-containing anhydrous ethanol dispersion into the solution obtained in step (3) and adding 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride aqueous solution under stirring to react, and then washing, centrifuging and drying the obtained product to obtain carbon nanotube / ferroferric oxide modified silica coated paraffin phase change microcapsule; (5) processing the carbon nanotube / ferroferric oxide modified silica coated paraffin phase change microcapsule, nucleating agent, polystyrene resin, lubricant and foaming agent obtained in step (4) into polystyrene foam plastic.

4. The production method according to claim 3, characterized by: In step (1), the use amount ratio of the paraffin, tetraethyl orthosilicate, hexadecyl trimethyl ammonium bromide, formamide and hydrochloric acid solution is 5-7 g:5-7 g:0.75-1.5 g:100-150 ml:100-150 ml; the concentration of the hydrochloric acid solution is 0.8-1.2 mol / L; the paraffin is single melting point paraffin or mixed paraffin compounded by multiple single melting point paraffins, and the melting point is 28-50℃; The heating temperature is 50-55℃, the stirring speed is 500-1000rpm, and the time is 30-60min; after adding the hydrochloric acid solution, the reaction time is 4-6h, and the standing time is 12-24h.

5. The production method according to claim 3, characterized by: In step (2), The mixing solution of the silica-coated paraffin microcapsule, water, FeCl3·6H2O and FeCl2·4H2O, and the amount of ammonia is 0.5-0.75g:40-60ml:10-15ml:4-8ml; The concentration of FeCl3·6H2O in the mixed solution is 0.001-0.002mol / ml, and the concentration of FeCl2·4H2O is 0.003-0.004mol / ml; The concentration of ammonia is 25-28wt%; The ultrasonic dispersion temperature is 40-60℃, the time is 30-50min; the heating stirring speed is 500-800rpm, the temperature is 70-80℃; after adding the mixed solution of FeCl3·6H2O and FeCl2·4H2O, the stirring time is 15-30min; the dropping speed of ammonia is 0.25-0.5ml / min, and the stirring time after adding ammonia is 10-30min.

6. The production method according to claim 3, characterized by: In step (3), The amount of Fe3O4 modified silica-coated paraffin microcapsule, anhydrous ethanol, 3-aminopropyl triethoxysilane and water is 0.5-0.75g:80-100ml:2-5ml:0.5-1.5ml; The heating stirring temperature is 35-45℃, the stirring speed is 500-700rpm, and the time is 10-30min; the reaction time is 18-24h.

7. The production method according to claim 3, wherein: In step (4), The amount of amino-functionalized Fe3O4 modified silica-coated paraffin microcapsule solution, carboxylated carbon nanotube, anhydrous ethanol and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride aqueous solution is 40-80ml:0.05-0.075g:40-80ml:0.5-1ml; The concentration of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride aqueous solution is 0.008-0.012g / mL; The reaction time is 20-24h.

8. The production method according to claim 3, characterized by: Step (5) specifically includes: adding the carbon nanotube / Fe3O4 modified silica-coated paraffin phase change microcapsule, nucleating agent, polystyrene resin and lubricant obtained in step (4) into a single screw extruder for mixing and stirring, high temperature plasticizing uniformly through the compression section and homogenization section, injecting a foaming agent, and preliminarily mixing and homogenizing through the mixing section; the obtained molten material is further mixed and cooled in a second single screw extruder, and then transferred to a mold, shaped through a leveling machine, and then obtained polystyrene foam plastic after secondary processing and cooling.

9. The production method according to claim 8, characterized by: In step (5), the screw of the single screw extruder is divided into four zones, the temperature of zone one is set to 165-175℃, the temperature of zone two is set to 175-185℃, the temperature of zone three is set to 185-195℃, and the temperature of zone four is set to 195-205℃.

10. The production method according to claim 8, characterized by: In step (5), the high temperature screw of the second single-screw extruder is divided into four zones, the temperature of the first zone is set to 195-205°C, the temperature of the second zone is set to 195-205°C, the temperature of the third zone is set to 175-185°C, and the temperature of the fourth zone is set to 145-155°C.

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