A graphite-modified polystyrene bead and its preparation method

Abstract

This application relates to the field of polymer materials, and specifically discloses a graphite-modified polystyrene bead and a preparation method thereof. A graphite-modified polystyrene bead, the raw materials used include graphite filler, flame retardant, antioxidant, lubricant, nucleating agent, pentane, antistatic agent and general polystyrene. The graphite filler is prepared by the following method: impregnating graphite particles in a pretreatment liquid according to a solid-liquid ratio of 1:(10-12), and performing heat treatment for 60-75 minutes to obtain the graphite filler. The pretreatment liquid includes sodium dihydrogen phosphate, sodium tetraborate, cashew phenol surfactant and water with a weight ratio of 10:(8-12):6.5:100; its preparation method is: feeding, proportioning and mixing, melt extrusion, decompression, pelletizing, cooling, drying, screening, coating, to obtain graphite-modified polystyrene beads. The products of this application have good flame retardancy, heat resistance and mechanical properties at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a graphite-modified polystyrene bead and a preparation method thereof. Background Art

[0002] Polystyrene (PS for short) is a polymer synthesized by free radical addition polymerization of styrene monomers. It has various properties and very wide applications. It has good chemical stability and is not easily corroded by acids, alkalis, solvents, etc. It has good insulation performance, high hardness, rigidity and strength. Among various PSs, expandable polystyrene can be used as packaging materials for various instruments, valuables, precision instruments, fruits, vegetables and aquatic products due to its characteristic of expanding upon heating to form a lightweight porous foam structure, or as thermal insulation fixing devices used when installing window frames in building construction.

[0003] Currently, technicians use polystyrene as raw material and rely on suspension method and extrusion method to obtain polystyrene beads, which improves the convenience of their subsequent processing, transportation and sales. Among them, the extrusion method is widely used due to its high material yield. However, with the continuous improvement of the market's requirements for material properties, higher requirements are also placed on the comprehensive properties of polystyrene beads prepared by the extrusion method. Summary of the Invention

[0004] In order to solve the above technical problems, the present application provides a graphite-modified polystyrene bead and a preparation method thereof.

[0005] In a first aspect, the present application provides a graphite-modified polystyrene bead, adopting the following technical solution: The raw materials used include the following components in parts by weight: 2 - 3 parts of graphite filler; 1 - 1.25 parts of flame retardant; 0.5 - 0.8 part of antioxidant; 0.05 - 0.08 part of lubricant; 0.25 - 0.5 part of nucleating agent; 3 - 4 parts of pentane; 40 - 50 parts of antistatic agent; 85 - 95 parts of general polystyrene; The graphite filler is prepared by the following method: impregnating graphite particles in a pretreatment solution according to a solid-liquid ratio of 1:(10 - 12), and performing heat treatment for 60 - 75 min to obtain the graphite filler, wherein the pretreatment solution includes sodium dihydrogen phosphate, sodium tetraborate, cardanol surfactant and water in a weight ratio of 10:(8 - 12):6.5:100.

[0006] By adopting the above technical solution, the present application first adds graphite filler with excellent heat resistance, high flame retardancy and strong mechanical stability to the system, which improves the heat insulation performance, flame retardancy and mechanical properties of polystyrene beads. A pretreatment solution is prepared by compounding sodium dihydrogen phosphate, sodium tetraborate, cardanol surfactant and water to conduct antioxidant treatment on graphite particles. The finally obtained graphite filler has better high-temperature resistance and antioxidant ability, so that the graphite-modified polystyrene beads have better flame retardancy, heat resistance and mechanical properties. The cardanol surfactant of the present application can further enhance the immersion and wetting degree between the pretreatment solution and graphite particles, so that the effective components (sodium dihydrogen phosphate, sodium tetraborate) in the pretreatment can better adhere to the surface of graphite particles and penetrate into the internal pores of graphite particles, thereby promoting the strengthening of the antioxidant ability of graphite particles. More importantly, compared with other surfactants (sodium dodecylbenzenesulfonate or alcohol ether sulfate), the cardanol surfactant of the present application has higher stability and lower critical micelle concentration, and thus has more excellent ability to promote the wetting degree.

[0007] Meanwhile, the present application also adds an antistatic agent to conduct antistatic treatment on polystyrene, reducing the possibility of generating static electricity during pre-expansion of the final product, helping the product to completely expel the foam particles and making its pre-expansion more stable, thereby improving the product quality. The forming density and strength of the foam board obtained after final foaming are guaranteed.

[0008] Generally speaking, the graphite-modified polystyrene beads of the present application contain graphite filler with good antioxidant ability, excellent heat resistance, high flame retardancy and strong mechanical stability, and are supplemented with an antistatic agent for coating treatment. In addition, the present application uses additional auxiliaries such as flame retardants, antioxidants, lubricants, nucleating agents, etc. After a series of preparation treatments, graphite-modified polystyrene beads with good flame retardancy, heat resistance and mechanical properties are finally obtained. The limiting oxygen index of the foam board obtained after its foaming can reach more than 32.5%, the combustion performance level can reach B1, the thermal conductivity is not higher than 0.0273 W / (m·K), the tensile strength is not lower than 0.279 MPa, and the compression strength is not lower than 0.24 MPa.

[0009] Among them, the flame retardant, antioxidant, lubricant and nucleating agent are any one or more of commercially available models. In the specific implementation manner of the present application, only methyl octabromodiphenyl ether and tricresyl phosphate are used as the flame retardant, antioxidant 168 and antioxidant 1076 are used as the antioxidant, N,N'-ethylenebisstearamide is used as the lubricant, and N,N-dimethyl-1,3-propanediamine is used as the nucleating agent for illustration, but this does not limit the protection scope of the present application. Those skilled in the art can make reasonable replacements according to the actual situation in actual use.

[0010] Preferably, the weight ratio of sodium dihydrogen phosphate, sodium tetraborate, cardanol surfactant and water is 10:10:5:100.

[0011] By adopting the above technical solution, the present application further controls the weight ratio of sodium dihydrogen phosphate, sodium tetraborate, cardanol surfactant and water, thereby optimizing the improvement degree of the antioxidant capacity of the pretreatment liquid for graphite particles. Experimental data shows that the limiting oxygen index, combustion performance level, compressive strength and tensile strength of the foam board obtained after foaming of the graphite-modified polystyrene beads at this time are all improved.

[0012] Preferably, the heat treatment time is divided into three sections, and the temperature is increased successively within each section. The specific operation is as follows: After immersing the graphite particles in the pretreatment liquid, the temperature is increased to 200 °C at a heating rate of 40-45 °C / min and then left standing, which is the first section of time. Subsequently, the temperature is increased to 300 °C at a heating rate of 20-25 °C / min and then left standing, which is the second section of time. Finally, the temperature is increased to 400 °C at a heating rate of 20-25 °C / min and then left standing, which is the third section of time.

[0013] By adopting the above technical solution, the present application divides the heat treatment time into three sections and increases the temperature successively within each section, which can significantly enhance the immersion wetting degree between the pretreatment liquid and the graphite particles, enabling the effective components in the pretreatment to better adhere to the surface of the graphite particles and penetrate into the internal pores of the graphite particles, thereby promoting the enhancement of the antioxidant capacity of the graphite particles.

[0014] Preferably, the preparation method of the cardanol surfactant includes the following steps: I. Acidify and ring-open cardanol glycidyl ether to obtain cardanol chlorohydrin ether; II. Mix tertiary amine and cardanol chlorohydrin ether with a molar ratio of (12-15):10, carry out condensation reaction at a temperature of 45-60 °C for 6-12 h, remove impurities, wash, and rotary evaporate to obtain the cardanol surfactant. The tertiary amine is any one of 3-diethylamino-1,2-propanediol or 3-diethylamino-1-propanol.

[0015] Preferably, in step II, the temperature of the condensation reaction is 50 °C and the time of the condensation reaction is 8 h.

[0016] Preferably, in step II, the tertiary amine is 3-diethylamino-1,2-propanediol.

[0017] By adopting the above technical solutions, the present application uses cardanol glycidyl ether as a raw material, first undergoes acidification and ring-opening, and then undergoes a condensation reaction with a tertiary amine to obtain a cardanol surfactant with a low critical micelle concentration, strong emulsifying property, and high solubilization property. Moreover, cardanol has the advantages of being green, renewable, degradable, low-toxicity, and low-cost. Therefore, the cardanol surfactant of the present application can not only effectively promote the immersion and wetting degree between the pretreatment liquid and graphite particles, but also has a certain environmental protection significance. In addition, the present application strictly controls the temperature and time of the condensation reaction, effectively improving the conversion rate of the cardanol surfactant, and uses 3-diethylamino-1,2-propanediol as the tertiary amine to carry out condensation with the ring-opening product, thereby further optimizing the emulsifying and solubilizing abilities of the cardanol surfactant.

[0018] Preferably, the preparation method of the antistatic agent includes the following steps: dispersing sodium polystyrene sulfonate and dodecyl trimethyl ammonium bromide in an aqueous polyurethane emulsion, and stirring until the system is in a uniform state to obtain an antistatic agent. The weight ratio of sodium polystyrene sulfonate, dodecyl trimethyl ammonium bromide, and the aqueous polyurethane emulsion is 1:1:(6-9).

[0019] By adopting the above technical solutions, the present application uses sodium polystyrene sulfonate, dodecyl trimethyl ammonium bromide, and aqueous polyurethane to prepare an antistatic agent with high adhesion, good thermal stability, and processing stability, thereby improving the product quality of graphite-modified polystyrene beads. Moreover, the present application also controls the weight ratio of sodium polystyrene sulfonate, dodecyl trimethyl ammonium bromide, and the aqueous polyurethane emulsion, and balances the stability and antistatic ability of the antistatic agent as much as possible. If the amount of the aqueous polyurethane emulsion is too large, the antistatic ability of the antistatic agent will be greatly reduced. If the amount of the aqueous polyurethane emulsion is too small, the adhesion ability of the antistatic agent will be weakened, and it will not be able to achieve a tight binding effect with the polystyrene beads.

[0020] Preferably, the weight ratio of sodium polystyrene sulfonate, dodecyl trimethyl ammonium bromide, and the aqueous polyurethane emulsion is 1:1:8.

[0021] By adopting the above technical solutions, the present application strictly controls the weight ratio of sodium polystyrene sulfonate, dodecyl trimethyl ammonium bromide, and the aqueous polyurethane emulsion to 1:1:8. Experimental data shows that at this time, the stability and antistatic ability of the antistatic agent reach the optimal balance, the effect of improving the quality of polystyrene beads reaches the best, and the tensile strength and compressive strength of the foamed board finally formed after foaming are both improved.

[0022] In a second aspect, the present application provides a method for preparing graphite-modified polystyrene beads, comprising the following steps: charging graphite filler, flame retardant, antioxidant, lubricant, nucleating agent, pentane and general polystyrene, then mixing the ingredients, melt-extruding, reducing pressure, pelletizing, cooling, drying, screening, and coating with an antistatic agent to obtain graphite-modified polystyrene beads, wherein the melting temperature during melt extrusion is 175-190°C.

[0023] By adopting the above technical solution, the present application first prepares the raw materials except the antistatic agent, mixes them according to weight, and then feeds them into an extruder for melt extrusion at a temperature of 175-190°C to ensure that the raw materials are fully melted and maintain the performance of the graphite filler. The pressure is then reduced to remove air or volatile substances in the raw materials to avoid the formation of bubbles or holes in the finished product as much as possible. After the molten material is extruded through the die head of the extruder, it is immediately cut into beads. In the present application, this process is carried out in water to quickly cool and solidify the beads. The beads are then further cooled to ensure their shape stability, dried, and the moisture on the surface and inside is removed. They are sieved to remove beads of unqualified size or shape. Finally, the sieved beads are coated to improve their antistatic properties. After a series of preparation processes, the present application finally obtains graphite-modified polystyrene beads with a high yield, good flame retardant properties, heat resistance and mechanical properties.

[0024] In summary, this application has the following beneficial technical effects:

[0025] 1. The graphite-modified polystyrene beads of the present application contain graphite fillers with good antioxidant capacity, excellent heat resistance, high flame retardancy, and strong mechanical stability, and are coated with an antistatic agent. Furthermore, the present application utilizes additional additives such as flame retardants, antioxidants, lubricants, and nucleating agents. Ultimately, graphite-modified polystyrene beads are obtained that have excellent flame retardancy, heat resistance, and mechanical properties. After foaming, the resulting foam board has a limiting oxygen index of over 32.5%, a combustion performance level of B1, a thermal conductivity of no more than 0.0273 W / (m·K), a tensile strength of no less than 0.279 MPa, and a compressive strength of no less than 0.24 MPa.

[0026] 2. This application utilizes sodium polystyrene sulfonate, dodecyltrimethylammonium bromide, and water-based polyurethane to produce an antistatic agent with high adhesion, good thermal stability, and processing stability, thereby improving the product quality of graphite-modified polystyrene beads;

[0027] 3. After a series of preparation processes, the present application finally produced graphite-modified polystyrene beads with high yield, good flame retardancy, heat resistance and mechanical properties. DETAILED DESCRIPTION

[0028] Material source

[0029] Unless otherwise specified, the raw materials used in this application are all commercially available products, specifically:

[0030] Cardanol glycidyl ether, CAS No. 171263-25-5;

[0031] 3-Diethylamino-1-propanol, CAS No. 156-87-6;

[0032] 3-Diethylamino-1,2-propanediol, CAS No. 621-56-7;

[0033] The silane coupling agent was purchased from Shandong Huachen New Materials Co., Ltd., KH-570;

[0034] The graphite particles were purchased from Hebei Ruitong Carbon Co., Ltd., with a carbon content of 95%. First, they were polished with sandpaper, the powder on the surface was washed with water, the surface moisture was dried with absorbent paper, then they were washed with alcohol for 6 minutes, and then dried to constant weight at a temperature of 100 °C for standby;

[0035] The waterborne polyurethane was purchased from DKSH Chemicals (Shanghai) Co., Ltd.;

[0036] The silicone surfactant was purchased from BASF, product number WE-3229;

[0037] ‌Sodium polystyrene sulfonate, CAS No. 25704-18-1;

[0038] Dodecyltrimethylammonium bromide, CAS No. 1119-94-4;

[0039] Sodium dodecylbenzenesulfonate, CAS No. 25155-30-0;

[0040] The alcohol ether sulfate was purchased from BASF, product number Disponil FES 77;

[0041] Methyl octabromide ether, CAS No. 97416-84-7;

[0042] Tricresyl phosphate, CAS No. 1330-78-5;

[0043] Antioxidant 168 and Antioxidant 1076 were purchased from Dongguan Xingyuan Chemical Co., Ltd.;

[0044] N,N’-Ethylenebisstearamide, CAS No. 110-30-5;

[0045] N,N-Dimethyl-1,3-propanediamine, CAS No. 109-55-7.

[0046] The present application will be further described in detail below in conjunction with preparation examples, examples and comparative examples.

[0047] Preparation Example 1.1

[0048] A method for preparing a cardanol surfactant, comprising the following steps:

[0049] Under the condition of continuous stirring in an ice-water bath, a cardanol glycidyl ether-ether solution with a volume ratio of 1:1 was slowly added dropwise to 1.1 kg of 37 wt% hydrochloric acid, wherein the amount of cardanol glycidyl ether used was 3.6 kg. Then the temperature was raised to 35 °C, and the reaction progress was monitored by thin-layer chromatography. After the cardanol glycidyl ether was completely consumed, the pH of the solution was adjusted to neutral with NaOH, allowed to stand for layering, the aqueous layer was extracted three times with ether, the ether layers were combined, dried with anhydrous sodium sulfate, and then the ether was removed by distillation to obtain a yellowish-brown viscous liquid, which was cardanol chlorohydrin ether;

[0050] 3-Diethylamino-1-propanol was dispersed in water, and the cardanol chlorohydrin ether obtained in step I was dispersed in ethanol. A cardanol chlorohydrin ether ethanol solution and a 30% sodium hydroxide solution were simultaneously added dropwise to the tertiary amine aqueous solution until the molar ratio of 3-diethylamino-1-propanol, cardanol chlorohydrin ether, and sodium hydroxide in the system was 12:10:14. The condensation reaction was carried out at a temperature of 60 °C for 12 h, the pH of the solution was adjusted to neutral with hydrochloric acid, the solvent was removed under reduced pressure, cold methanol was added to remove the sodium chloride formed in the reaction, most of the methanol was removed under reduced pressure, and then n-hexane was added for washing and separation. The lower layer was rotary-evaporated to remove the solvent to obtain a cardanol surfactant, and the conversion rate was detected to be 78.5%.

[0051] Preparation Example 1.2

[0052] A method for preparing a cardanol surfactant, comprising the following steps:

[0053] Under the condition of continuous stirring in an ice-water bath, a cardanol glycidyl ether-ether solution with a volume ratio of 1:1 was slowly added dropwise to 1.1 kg of 37 wt% hydrochloric acid, wherein the amount of cardanol glycidyl ether used was 3.6 kg. Then the temperature was raised to 35 °C, and the reaction progress was monitored by thin-layer chromatography. After the cardanol glycidyl ether was completely consumed, the pH of the solution was adjusted to neutral with NaOH, allowed to stand for layering, the aqueous layer was extracted three times with ether, the ether layers were combined, dried with anhydrous sodium sulfate, and then the ether was removed by distillation to obtain a yellowish-brown viscous liquid, which was cardanol chlorohydrin ether;

[0054] Disperse 3 - diethylamino - 1 - propanol in water, and then disperse the cardanol chlorohydrin ether obtained in Step I in ethanol. Dropwise add the cardanol chlorohydrin ether ethanol solution and 30% sodium hydroxide solution to the tertiary amine aqueous solution simultaneously until the molar ratio of 3 - diethylamino - 1 - propanol, cardanol chlorohydrin ether, and sodium hydroxide in the system is 15:10:14. Carry out a condensation reaction at 45 °C for 6 h, adjust the pH of the solution to neutral with hydrochloric acid, remove the solvent under reduced pressure, add cold methanol to remove the sodium chloride generated by the reaction, remove most of the methanol under reduced pressure, add n - hexane for washing and separation, and rotary evaporate the solvent from the lower layer to obtain the cardanol surfactant. The conversion rate is detected to be 82.3%.

[0055] Preparation Example 1.3

[0056] The preparation method of the cardanol surfactant is different from Preparation Example 1.1 in that: in Step II, the temperature of the condensation reaction is 50 °C and the time of the condensation reaction is 8 h, and the rest are the same as Preparation Example 1.1. The obtained cardanol surfactant has a detected conversion rate of 97.8%.

[0057] Preparation Example 1.4

[0058] The preparation method of the cardanol surfactant is different from Preparation Example 1.1 in that: in Step II, the temperature of the condensation reaction is 40 °C and the time of the condensation reaction is 15 h, and the rest are the same as Preparation Example 1.1. The obtained cardanol surfactant has a detected conversion rate of 64.3%.

[0059] Preparation Example 1.5

[0060] The preparation method of the cardanol surfactant is different from Preparation Example 1.1 in that: in Step II, the temperature of the condensation reaction is 65 °C and the time of the condensation reaction is 6 h, and the rest are the same as Preparation Example 1.1. The obtained cardanol surfactant has a detected conversion rate of 62.7%.

[0061] Preparation Example 1.6

[0062] The preparation method of the cardanol surfactant is different from Preparation Example 1.3 in that: 3 - diethylamino - 1 - propanol is replaced by 3 - diethylamino - 1,2 - propanediol, and the rest are the same as Preparation Example 1.1. The obtained cardanol surfactant has a detected conversion rate of 97.5%.

[0063] Preparation Example 2.1

[0064] The preparation method of the graphite filler includes the following steps:

[0065] Put 7.5 kg of sodium dihydrogen phosphate into 100 L of water, stir well until completely dissolved, then add another 2.5 kg of sodium dihydrogen phosphate, and stir well until the system becomes transparent with no residual impurities. Then add 8 kg of sodium tetraborate to the system and stir until completely dissolved, the system is transparent with no residual impurities. Finally, add 6.5 kg of the cardanol surfactant prepared in Preparation Example 1.1, stir evenly to obtain the pretreatment liquid; Immerse the treated graphite particles in the pretreatment liquid according to a solid-liquid ratio of 1:10, heat-treat for 75 min, then naturally cool to room temperature, and wash with alcohol for 10 min to obtain the graphite filler.

[0066] Preparation Example 2.2

[0067] A method for preparing graphite filler, comprising the following steps:

[0068] Put 7.5 kg of sodium dihydrogen phosphate into 100 L of water, stir well until completely dissolved, then add another 2.5 kg of sodium dihydrogen phosphate, and stir well until the system becomes transparent with no residual impurities. Then add 12 kg of sodium tetraborate to the system and stir until completely dissolved, the system is transparent with no residual impurities. Finally, add 6.5 kg of the cardanol surfactant prepared in Preparation Example 1.2, stir evenly to obtain the pretreatment liquid; Immerse the treated graphite particles in the pretreatment liquid according to a solid-liquid ratio of 1:12, heat-treat for 60 min, then naturally cool to room temperature, and wash with alcohol for 10 min to obtain the graphite filler.

[0069] Preparation Example 2.3

[0070] The method for preparing graphite filler is different from Preparation Example 2.1 in that the amount of sodium tetraborate used is 10 kg, and the rest are the same as Preparation Example 2.1.

[0071] Preparation Example 3.1

[0072] The method for preparing graphite filler is different from Preparation Example 2.1 in that the heat-treatment time is divided into three equal segments of 25 min, and the temperature is increased successively within each period. The specific operation is as follows: Immerse the treated graphite particles in the pretreatment liquid according to a solid-liquid ratio of 1:10, heat up to 200 °C at a heating rate of 45 °C / min and then stand still, the total heating and standing time is 25 min. Then heat up to 300 °C at a heating rate of 20 °C / min and then stand still, the total heating and standing time is 25 min. Finally, heat up to 400 °C at a heating rate of 20 °C / min and then stand still, the total heating and standing time is 25 min.

[0073] Preparation Example 3.2

[0074] The preparation method of the graphite packing, different from Preparation Example 2.1, is that the heat treatment time is evenly divided into three segments of 25 min, and the temperature is increased successively within each period. The specific operation is as follows: The treated graphite particles are impregnated in the pretreatment liquid at a solid-liquid ratio of 1:10, heated to 200 °C at a heating rate of 40 °C / min and then left standing. The total heating and standing time is 25 min. Subsequently, it is heated to 300 °C at a heating rate of 25 °C / min and then left standing. The total heating and standing time is 25 min. Finally, it is heated to 400 °C at a heating rate of 25 °C / min and then left standing. The total heating and standing time is 25 min.

[0075] Preparation Examples 4.1 - 4.3

[0076] The preparation method of the graphite packing, different from Preparation Example 2.1, is that the cardanol surfactants prepared in Preparation Example 1.1 are respectively replaced with the cardanol surfactants prepared in Preparation Examples 1.3 - 1.5, and the rest are the same as Preparation Example 2.1.

[0077] Preparation Example 4.4

[0078] The preparation method of the graphite packing, different from Preparation Example 4.1, is that the cardanol surfactant prepared in Preparation Example 1.3 is replaced with the cardanol surfactant prepared in Preparation Example 1.6, and the rest are the same as Preparation Example 4.1.

[0079] Preparation Example 5.1

[0080] The preparation method of the antistatic agent includes the following steps:

[0081] Weigh waterborne polyurethane, silane coupling agent, isopropanol, silicone surfactant and water in a weight ratio of 5:0.5:2:1.2:20, mix and stir evenly to obtain a waterborne polyurethane emulsion. Subsequently, 1 kg of sodium polystyrene sulfonate and 1 kg of dodecyltrimethylammonium bromide are dispersed in 6 kg of the waterborne polyurethane emulsion, and stirred until the state in the system is uniform to obtain the antistatic agent.

[0082] Preparation Example 5.2

[0083] The preparation method of the antistatic agent includes the following steps:

[0084] Weigh waterborne polyurethane, silane coupling agent, isopropanol, silicone surfactant and water in a weight ratio of 5:0.5:2:1.2:20, mix and stir evenly to obtain a waterborne polyurethane emulsion. Subsequently, 1 kg of sodium polystyrene sulfonate and 1 kg of dodecyltrimethylammonium bromide are dispersed in 9 kg of the waterborne polyurethane emulsion, and stirred until the state in the system is uniform to obtain the antistatic agent.

[0085] Preparation Example 5.3

[0086] Preparation method of antistatic agent, different from Preparation Example 5.1 in that 1 kg of sodium polystyrene sulfonate and 1 kg of dodecyltrimethylammonium bromide are dispersed in 7 kg of aqueous polyurethane emulsion, and stirred until the system is homogeneous to obtain the antistatic agent.

[0087] Preparation Example 5.4

[0088] Preparation method of antistatic agent, different from Preparation Example 5.1 in that 1 kg of sodium polystyrene sulfonate and 1 kg of dodecyltrimethylammonium bromide are dispersed in 8 kg of aqueous polyurethane emulsion, and stirred until the system is homogeneous to obtain the antistatic agent.

[0089] Comparative Preparation Example 1

[0090] Preparation method of graphite filler, different from Preparation Example 2.1 in that the cardanol surfactant prepared in Preparation Example 1.1 is replaced with sodium dodecylbenzenesulfonate, and the rest are the same as Preparation Example 2.1.

[0091] Comparative Preparation Example 2

[0092] Preparation method of graphite filler, different from Preparation Example 2.1 in that the cardanol surfactant prepared in Preparation Example 1.1 is replaced with alcohol ether sulfate, and the rest are the same as Preparation Example 2.1.

[0093] Example 1.1

[0094] A preparation method of graphite-modified polystyrene beads, comprising the following steps:

[0095] S1. Feeding: Pour the graphite filler, flame retardant, antioxidant, lubricant, nucleating agent, pentane and general polystyrene prepared in Preparation Example 2.1 into the hoppers of the corresponding feeding stations respectively, and perform positive and negative pressure system feeding, and convey the materials to the receiving hopper through the sending tank respectively;

[0096] S2. Batching and mixing: Use central control to control batching, convey the materials in the receiving hopper to the weighing scale respectively, and perform automatic batching according to the required addition amount, and the addition amount is shown in Table 1;

[0097] S3. Melting extrusion and decompression: The material is fed from the loss-in-weight scale to the melt pump, the melting temperature is set at 175 °C, the rotation speed of the melt pump is set at 80 r / min, and then decompression exhaust is carried out;

[0098] S4. Pelletizing: Convey the material to the pelletizer, extrude it through a twin-screw extruder, and cut it into material particles by a pelletizing knife. The temperature of the template oil temperature machine is set at 250 °C, and the rotation speed of the cutter head is set at 800 r / min;

[0099] S5, Drying: The material particles are dehydrated and dried from the pelletizing chamber to a centrifugal dryer.

[0100] S6, Screening: The dried material is transported to a screening machine.

[0101] S7, Coating: The screened material is coated. The antistatic agent used for coating is the antistatic agent prepared in Preparation Example 5.1, and the dosage is shown in Table 1.

[0102] S8, Finished Product: The coated material is sent into a finished product tank through a conveying pipeline to obtain graphite-modified polystyrene beads.

[0103] Example 1.2

[0104] A method for preparing graphite-modified polystyrene beads, comprising the following steps:

[0105] S1, Feeding: The graphite filler, flame retardant, antioxidant, lubricant, nucleating agent, pentane and general polystyrene prepared in Preparation Example 2.2 are respectively poured into the hoppers of the corresponding feeding stations, and are fed through a positive and negative pressure system. The materials are respectively transported to the receiving hopper through a sending tank.

[0106] S2, Batching and Mixing: The materials in the receiving hopper are respectively transported to a weighing scale for batching under the control of a central control system. According to the required addition amount, automatic batching is carried out, and the addition amount is shown in Table 1.

[0107] S3, Melting, Extruding and Decompressing: The material is discharged from the loss-in-weight scale to a melt pump. The melting temperature is set at 190 °C, and the rotational speed of the melt pump is set at 80 r / min. Subsequently, decompression and exhaust are carried out.

[0108] S4, Pelletizing: The material is transported to a pelletizing machine. After being extruded by a twin-screw extruder, it is cut into material particles by a pelletizing knife. The temperature of the die plate oil temperature machine is set at 250 °C, and the rotational speed of the cutter head is set at 800 r / min.

[0109] S5, Drying: The material particles are dehydrated and dried from the pelletizing chamber to a centrifugal dryer.

[0110] S6, Screening: The dried material is transported to a screening machine.

[0111] S7, Coating: The screened material is coated. The antistatic agent used for coating is the antistatic agent prepared in Preparation Example 5.2, and the dosage is shown in Table 1.

[0112] S8, Finished Product: The coated material is sent into a finished product tank through a conveying pipeline to obtain graphite-modified polystyrene beads.

[0113] Table 1 Raw material dosage of Examples 1.1 - 1.2 / kg

[0114]

[0115] Example 1.3

[0116] A preparation method of graphite-modified polystyrene beads, which is different from Example 1.1 in that in step S1, the graphite filler prepared in Preparation Example 2.1 is replaced with the graphite filler prepared in Preparation Example 2.3, and the rest are the same as in Example 1.1.

[0117] Examples 2.1 - 2.2

[0118] A preparation method of graphite-modified polystyrene beads, which is different from Example 1.1 in that in step S1, the graphite filler prepared in Preparation Example 2.1 is respectively replaced with the graphite fillers prepared in Preparation Examples 3.1 - 3.2, and the rest are the same as in Example 1.1.

[0119] Examples 3.1 - 3.3

[0120] A preparation method of graphite-modified polystyrene beads, which is different from Example 1.1 in that in step S1, the graphite filler prepared in Preparation Example 2.1 is respectively replaced with the graphite fillers prepared in Preparation Examples 4.1 - 4.3, and the rest are the same as in Example 1.1.

[0121] Example 4

[0122] A preparation method of graphite-modified polystyrene beads, which is different from Example 3.1 in that in step S1, the graphite filler prepared in Preparation Example 4.1 is replaced with the graphite filler prepared in Preparation Example 4.4, and the rest are the same as in Example 3.1.

[0123] Examples 5.1 - 5.2

[0124] A preparation method of graphite-modified polystyrene beads, which is different from Example 1.1 in that in step S7, the antistatic agent prepared in Preparation Example 5.1 is respectively replaced with the antistatic agents prepared in Preparation Examples 5.3 - 5.4, and the rest are the same as in Example 1.1.

[0125] Comparative Example 1

[0126] It is different from Example 1.1 in that in step S1, the graphite filler prepared in Preparation Example 2.1 is replaced with graphite particles without any treatment, and the rest are the same as in Example 1.1.

[0127] Comparative Examples 2.1 - 2.2

[0128] It is different from Example 1.1 in that in step S1, the graphite filler prepared in Preparation Example 2.1 is respectively replaced with the graphite fillers prepared in Comparative Preparation Examples 1 - 2, and the rest are the same as in Example 1.1.

[0129] Performance Detection

[0130] 1. Limiting oxygen index: The graphite-modified polystyrene beads obtained from the examples and comparative examples were made into standard specimens according to GB / T 3399-1982, and then tested according to the records in GB / T 2406.2-2009. The specific experimental data are shown in Table 2;

[0131] 2. Combustion performance test: The graphite-modified polystyrene beads obtained from the examples and comparative examples were made into standard specimens according to GB / T 3399-1982, and then the samples were classified according to the records in GB 8624-2012. The results are shown in Table 2;

[0132] 3. Thermal conductivity: The graphite-modified polystyrene beads obtained from the examples and comparative examples were made into standard specimens according to GB / T 3399-1982, and the thermal conductivity (W / (m·K)) was measured using the guarded hot plate method. The specific experimental data are shown in Table 2;

[0133] 4. Tensile strength: A dumbbell-shaped foam board was made according to the records in GB 9641-1988, and the tensile performance was tested using a testing machine at 25°C. The moving speed of the fixture was 5±1 mm / min. The specific experimental data are shown in Table 2;

[0134] 5. Compressive strength: The graphite-modified polystyrene beads obtained from the examples and comparative examples were made into standard specimens according to GB / T 3399-1982, and the compressive strength at 10% deformation was measured according to the records in GB / T 8813-2020. The specific experimental data are shown in Table 2.

[0135] Table 2 Performance Detection Table

[0136]

[0137] Data Analysis:

[0138] As can be seen from Table 2, the foam boards made of the graphite-modified polystyrene beads in Examples 1.1-1.2 of this application have a limiting oxygen index of up to 32.5-32.6%, a combustion performance level of up to B1, a thermal conductivity of 0.0271-0.0273 W / (m·K), a tensile strength of 0.279 MPa, and a compressive strength of 0.24-0.242 MPa. It is proved that the graphite-modified polystyrene beads of this application contain graphite fillers with good antioxidant ability, excellent heat resistance, high flame retardancy, and strong mechanical stability, and are supplemented with antistatic agents for coating treatment. Coupled with the use of additional additives such as flame retardants, antioxidants, lubricants, and nucleating agents in this application, after a series of preparation treatments, graphite-modified polystyrene beads with good flame retardancy, heat resistance, and mechanical properties are finally obtained;

[0139] All the data of Example 1.3 are superior to those of Example 1.1, proving that by controlling the weight ratios of sodium dihydrogen phosphate, sodium tetraborate, cardanol surfactant and water in this application, the improvement degree of the antioxidant ability of the pretreatment liquid for graphite particles can be optimized. At this time, the limiting oxygen index, combustion performance level, compressive strength and tensile strength of the foam board obtained after foaming of the graphite-modified polystyrene beads are all improved;

[0140] All the data of Examples 2.1 - 2.2 are superior to those of Example 1.1, proving that by dividing the heat treatment time into three equal segments and heating up successively within each period of time in this application, the immersion wetting degree between the pretreatment liquid and graphite particles can be significantly enhanced, enabling the effective components in the pretreatment to better adhere to the surface of graphite particles and thus penetrate into the internal pores of graphite particles, thereby promoting the strengthening of the antioxidant ability of graphite particles;

[0141] All the data of Example 4 are superior to those of Example 1.1, proving that by using 3 - diethylamino - 1,2 - propanediol as a tertiary amine to condense with the ring - opening product in this application, the emulsifying and solubilizing abilities of the cardanol surfactant are further optimized;

[0142] The thermal conductivity of Example 5.2 is lower than that of Example 1.1 and Example 5.1, while the tensile strength and compressive strength are higher than those of Example 1.1 and Example 5.1. This proves that by controlling the weight ratios of sodium polystyrene sulfonate, dodecyltrimethylammonium bromide and aqueous polyurethane emulsion in this application, the stability and antistatic ability of the antistatic agent are balanced as much as possible. If the dosage of the aqueous polyurethane emulsion is too large, the antistatic ability of the antistatic agent will be greatly reduced. If the dosage of the aqueous polyurethane emulsion is too small, the adhesion ability of the antistatic agent will be weakened, and it will not be able to achieve a tight binding effect with the polystyrene beads;

[0143] All the data of Comparative Example 1 are inferior to those of Example 1.1, proving that by compounding sodium dihydrogen phosphate, sodium tetraborate, cardanol surfactant and water to obtain a pretreatment liquid and using the pretreatment liquid to perform antioxidant treatment on graphite particles in this application, the finally obtained graphite filler can have better high - temperature resistance and antioxidant ability, enabling the graphite - modified polystyrene beads to have better flame - retardant performance, heat - resistant performance and mechanical properties;

[0144] The data of Comparative Examples 2.1 - 2.2 are all inferior to those of Example 1.1, which proves that the cardanol surfactant of the present application can further enhance the immersion wetting degree between the pretreatment liquid and the graphite particles, so that sodium dihydrogen phosphate and sodium tetraborate in the pretreatment can better adhere to the surface of the graphite particles and penetrate into the internal pores of the graphite particles, thereby promoting the strengthening of the antioxidant ability of the graphite particles. More importantly, compared with other surfactants, the cardanol surfactant of the present application has higher stability and lower critical micelle concentration, and thus has a more excellent ability to promote the immersion wetting degree.

[0145] The embodiments of this specific implementation manner are all preferred embodiments of the present application, and do not limit the protection scope of the present application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A graphite-modified polystyrene bead, characterized in that, The raw materials used include the following components in parts by weight: 2-3 parts of graphite filler; 1-1.25 parts of flame retardant; 0.5-0.8 part of antioxidant; 0.05-0.08 part of lubricant; 0.25-0.5 part of nucleating agent; 3-4 parts of pentane; 40-50 parts of antistatic agent; 85-95 parts of general polystyrene; the graphite filler is prepared by the following method: The graphite particles are impregnated in the pretreatment liquid according to a solid-liquid ratio of 1:(10-12), and heat-treated for 60-75 min to obtain the graphite filler. The pretreatment liquid includes sodium dihydrogen phosphate, sodium tetraborate, cardanol surfactant and water with a weight ratio of 10:(8-12):6.5:

100. The time of the heat treatment is divided into three equal segments, and the temperature is increased successively within each segment. The specific operation is as follows: after the graphite particles are impregnated in the pretreatment liquid, the temperature is increased to 200 °C at a heating rate of 40-45 °C / min and then left standing, which is the first segment of time. Subsequently, the temperature is increased to 300 °C at a heating rate of 20-25 °C / min and then left standing, which is the second segment of time. Finally, the temperature is increased to 400 °C at a heating rate of 20-25 °C / min and then left standing, which is the third segment of time. The preparation method of the antistatic agent includes the following steps: sodium polystyrene sulfonate and dodecyl trimethyl ammonium bromide are dispersed in an aqueous polyurethane emulsion, and stirred until the state in the system is uniform to obtain the antistatic agent. The weight ratio of sodium polystyrene sulfonate, dodecyl trimethyl ammonium bromide and the aqueous polyurethane emulsion is 1:1:

8.

2. The graphite-modified polystyrene beads according to claim 1, characterized in that The weight ratio of sodium dihydrogen phosphate, sodium tetraborate, cardanol surfactant and water is 10:10:6.5:

100.

3. A graphite-modified polystyrene bead according to claim 1, characterized in that, The preparation method of the cardanol surfactant includes the following steps: I. Acidify and ring-open cardanol glycidyl ether to obtain cardanol chlorohydrin ether; II. Mix tertiary amine and cardanol chlorohydrin ether with a molar ratio of (12-15):10, carry out a condensation reaction at a temperature of 45-60 °C for 6-12 h, remove impurities, wash, and rotary evaporate to obtain the cardanol surfactant. The tertiary amine is any one of 3-diethylamino-1,2-propanediol or 3-diethylamino-1-propanol.

4. A graphite-modified polystyrene bead according to claim 3, characterized in that, In the step II, the temperature of the condensation reaction is 50 °C, and the time of the condensation reaction is 8 h.

5. A graphite-modified polystyrene bead according to claim 4, characterized in that, In the step II, the tertiary amine is 3-diethylamino-1,2-propanediol.

6. A method for preparing the graphite-modified polystyrene beads according to any one of claims 1-5, characterized in that, It includes the following steps: feeding the graphite filler, flame retardant, antioxidant, lubricant, nucleating agent, pentane and general polystyrene, then proportioning and mixing, melt-extruding, depressurizing, pelletizing, cooling, drying, screening, and coating with the antistatic agent to obtain graphite-modified polystyrene beads. The melting temperature during the melt-extrusion is 175-190 °C.

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