A process and molding method for producing large size high performance polystyrene materials

Abstract

The application relates to the polystyrene material field, in particular to a process and a forming method for preparing large-size high-performance polystyrene material. The process comprises the following steps: step 1, a certain amount of divinylbenzene monomer is placed in a reaction kettle, and 1% to 6% of the initiator based on the mass fraction of the divinylbenzene is added; a prepolymerization reaction is carried out to obtain a polystyrene prepolymer with a set viscosity, which is named A1; step 2, a certain amount of styrene monomer is placed in a reaction kettle, and 2.5% to 10% of the initiator based on the mass fraction of the styrene is added. The divinylbenzene is preferentially prepolymerized, the heat release in the forming polymerization process of the polystyrene material is reduced, the risk of explosive polymerization of the large-size polystyrene material due to thermal runaway is reduced, and the difficulty of the forming process control of the large-size material is improved; and the addition of the polydivinylbenzene improves the mechanical strength of the polystyrene material.

Description

Technical Field

[0001] This application relates to the field of polystyrene materials, and more particularly to a process and molding method for preparing large-size high-performance polystyrene materials. Background Technology

[0002] Polystyrene is a versatile plastic with a light transmittance of up to 92% and excellent optical properties. It maintains good electrical insulation and high-frequency characteristics even under humid or high-temperature conditions, and has the strongest radiation resistance of all plastics. At the same time, it is rigid, has good rigidity, and high dimensional stability, so it has broad application potential in high-performance engineering components, high-frequency capacitors, and the nuclear industry.

[0003] Existing publicly available technologies generally involve prepolymerizing styrene monomers to a certain viscosity, then adding a specific proportion of crosslinking agent to prepare a prepolymer solution with a certain viscosity. High-performance polystyrene materials are then produced through heating and polymerization. However, when the crosslinking agent content is low, the material's mechanical strength is actually worse than when no crosslinking agent is added. During polymerization, white particles and cavities appear inside the material, leading to performance failure. Conversely, high crosslinking agent content causes the material to become brittle and its mechanical strength decreases. Furthermore, due to the highly reactive chemical double bonds inherent in divinylbenzene, the preparation process requires strict control. Large-size polystyrene materials may experience dimensional deformation, explosive polymerization failure, and poor mechanical strength during preparation. Summary of the Invention

[0004] The purpose of this application is to propose a process and molding method for preparing large-size high-performance polystyrene materials, which solves the problems of thermal runaway polymerization and cracking during the molding of large-size materials, while improving the mechanical strength of polystyrene materials and reducing the difficulty of controlling the molding process.

[0005] This application is implemented as follows: A process and molding method for preparing large-size high-performance polystyrene materials, comprising the following steps: Step 1, a certain amount of divinylbenzene monomer is placed in a reaction vessel, and an initiator accounting for 1% to 6% of the mass fraction of divinylbenzene is added; a prepolymerization reaction is carried out to obtain a polyvinylbenzene prepolymer with a set viscosity, which is named A1; Step 2, a certain amount of styrene monomer is placed in a reaction vessel, and an initiator accounting for 2.5% to 10% of the mass fraction of styrene is added; a prepolymerization reaction is carried out to obtain a polyvinylbenzene prepolymer with a set viscosity, which is named A2; Step 3, a certain amount of divinylbenzene and styrene monomer are thoroughly mixed, and an initiator is added to fully dissolve and uniformly mix, forming a mixture named A3; Step 4, A1 and A2 are mixed uniformly in a mixing vessel, and then A3 is added for viscosity adjustment and control, resulting in a mixture named A4. A4 is heated and cured to obtain the high-performance polystyrene material.

[0006] Furthermore, the initiator is one or a combination of several of azobisisobutyronitrile, benzoyl peroxide, and cumene hydroperoxide.

[0007] Furthermore, in step 3, divinylbenzene and styrene monomers are thoroughly mixed in a mass ratio of 0.25:1 to 0.4:1.

[0008] Furthermore, in step 4, A1 and A2 are mixed evenly in a mixing tank at a mass ratio of 0.15:1 to 0.35:1.

[0009] Furthermore, in step 1, high-purity nitrogen gas is introduced into the reactor for gas protection to carry out the prepolymerization reaction. The polymerization temperature is 60°C to 74°C, and the polymerization time is 45 minutes to 90 minutes. After the material reaches the set viscosity, it is cooled to 20°C to 25°C by observing the material with an online viscometer.

[0010] Furthermore, in step 2, high-purity nitrogen gas is introduced into the reactor for gas protection to carry out the prepolymerization reaction. The polymerization temperature is 78°C to 82°C, and the polymerization time is 90 minutes to 120 minutes. After the material reaches the set viscosity, it is cooled to 20°C to 25°C by observing the material through an online viscometer.

[0011] By implementing the above technical solution, this application first prepolymerizes divinylbenzene to prepare polyvinylbenzene with a certain viscosity, and then prepolymerizes styrene to prepare polystyrene with a certain viscosity. Next, the polyvinylbenzene and polystyrene are thoroughly mixed in a dispersion vessel, and the viscosity of the mixture in the dispersion vessel is adjusted using a mixture of styrene monomer and divinylbenzene. Finally, a certain proportion of initiator is added. This preferential prepolymerization of divinylbenzene reduces the heat release during the polystyrene molding polymerization process, lowers the risk of thermal runaway and explosive polymerization in large-size polystyrene materials, and increases the difficulty of controlling the molding process of large-size materials. The addition of polyvinylbenzene further enhances the mechanical strength of the polystyrene material. Detailed Implementation

[0012] This application is not limited to the following embodiments, and the specific implementation method can be determined according to the technical solution of this application and the actual situation.

[0013] A process and molding method for preparing large-size high-performance polystyrene materials includes the following steps: Step 1, a certain amount of divinylbenzene monomer is placed in a reaction vessel, and an initiator accounting for 1% to 6% of the mass fraction of divinylbenzene is added; a prepolymerization reaction is carried out to obtain a polyvinylbenzene prepolymer with a set viscosity, which is named A1; Step 2, a certain amount of styrene monomer is placed in a reaction vessel, and an initiator accounting for 2.5% to 10% of the mass fraction of styrene is added; a prepolymerization reaction is carried out to obtain a polyvinylbenzene prepolymer with a set viscosity, which is named A2; Step 3, a certain amount of divinylbenzene and styrene monomer are thoroughly mixed, and an initiator is added to fully dissolve and uniformly mix, forming a mixture named A3; Step 4, A1 and A2 are mixed uniformly in a mixing vessel, and then A3 is added for viscosity adjustment and control, resulting in a mixture named A4. A4 is then heated and cured to obtain the high-performance polystyrene material.

[0014] The initiator is one or a combination of several of azobisisobutyronitrile, benzoyl peroxide, and cumene hydroperoxide.

[0015] In step 3, divinylbenzene and styrene monomers are thoroughly mixed at a mass ratio of 0.25:1 to 0.4:1.

[0016] In step 4, A1 and A2 are mixed evenly in a mixing tank at a mass ratio of 0.15:1 to 0.35:1.

[0017] In step 1, high-purity nitrogen gas is introduced into the reactor for gas protection to carry out the prepolymerization reaction. The polymerization temperature is 60℃ to 74℃ and the polymerization time is 45 minutes to 90 minutes. After the material reaches the set viscosity, it is cooled to 20℃ to 25℃ by observing the material through an online viscometer.

[0018] In step 2, high-purity nitrogen gas is introduced into the reactor for gas protection to carry out the prepolymerization reaction. The polymerization temperature is 78℃ to 82℃, and the polymerization time is 90 minutes to 120 minutes. After the material reaches the set viscosity, it is cooled to 20℃ to 25℃ by observing the material through an online viscometer.

[0019] This process of prepolymerizing divinylbenzene reduces the heat release during the polymerization of polystyrene materials, lowers the risk of thermal runaway polymerization in large-size polystyrene materials, and increases the difficulty of controlling the molding process of large-size materials; the addition of divinylbenzene further enhances the mechanical strength of polystyrene materials.

[0020] Divinylbenzene is prepolymerized in a reactor to prepare polydivinylbenzene (PDVB) of a certain viscosity. Then, styrene is prepolymerized in a reactor to prepare polystyrene (PS) of a certain viscosity. PDVB and PS are then thoroughly mixed in a dispersion vessel, and the viscosity of the mixture in the dispersion vessel is adjusted with A3. Finally, a certain proportion of initiator is added to ensure thorough mixing of the above components. The mixture is then extruded and cast to produce large-size, high-performance polystyrene materials. Example 1

[0021] 40 kg of divinylbenzene monomer was weighed and placed in a reactor. Then, azobisisobutyronitrile (AIBN) was added, accounting for 2.25% of the mass of divinylbenzene. High-purity nitrogen was introduced into the reactor for gas protection. The equipment was started to carry out a thermal prepolymerization reaction at a polymerization temperature of 62°C for 65 minutes. The viscosity of the material was observed using an online viscometer. When the viscosity of the material reached 420 mPa·s, the cooling was immediately started. The temperature was lowered to 25°C, and the viscosity of the material was measured again to be approximately 870 mPa·s. The polyvinylbenzene prepolymer (p-PDVB) prepared in this step was named A1.

[0022] 85 kg of styrene monomer was weighed and placed in a reactor. Benzoyl peroxide (BPO) was then added, accounting for 2.5% of the styrene mass. High-purity nitrogen was introduced into the reactor for gas protection. The equipment was started to carry out a thermal prepolymerization reaction at a polymerization temperature of 80°C for 80 minutes. The viscosity of the material was observed using an online viscometer. When the viscosity of the material reached 6500 mPa·s, the cooling process was immediately initiated. The temperature was lowered to 25°C, and the viscosity of the material was measured again, which was 14000 mPa·s. The polystyrene (p-PS) prepared in this step was named A2.

[0023] Weigh divinylbenzene and styrene monomers at a mass ratio of 0.35:1 and mix them thoroughly. At the same time, add cumene hydroperoxide (CHP) at a mass ratio of 5% of the sum of divinylbenzene and styrene and mix thoroughly and evenly. The resulting mixture is named A3.

[0024] Mix A1 and A2 in a mixing tank at a mass ratio of 0.16:1 until homogeneous. Test the viscosity at 25 degrees Celsius; it should be 12000±100 mPa·s. If the viscosity exceeds this range, add A3 for final viscosity adjustment. Strict control of material viscosity is crucial in this step to prepare for subsequent extrusion and casting. The final mixture formed in this process is named A4.

[0025] The A4 material is placed into a 1000*1000*100mm square mold using an extrusion casting unit. Pressure is applied to slowly extrude the material and evenly fill the entire mold cavity. Then, according to a specific temperature control program, the material is heated and cured. After demolding, high-performance polystyrene material can be obtained. Example 2

[0026] 80 kg of divinylbenzene monomer was weighed and placed in a reactor. Then, azobisisobutyronitrile (AIBN) was added, accounting for 2.25% of the mass fraction of divinylbenzene. High-purity nitrogen was introduced into the reactor for gas protection. The equipment was started to carry out a thermal prepolymerization reaction at a polymerization temperature of 62°C for 65 minutes. The viscosity of the material was observed using an online viscometer. When the viscosity of the material reached 430 mPa·s, the cooling was immediately started. The temperature was lowered to 25°C, and the viscosity of the material was measured again to be approximately 960 mPa·s. The polyvinylbenzene prepolymer (p-PDVB) prepared in this step was named A1.

[0027] 155 kg of styrene monomer was weighed and placed in a reactor. Benzoyl peroxide (BPO) was added, accounting for 2.5% of the styrene mass. High-purity nitrogen was introduced into the reactor for gas protection. The equipment was started to carry out a thermal prepolymerization reaction at a polymerization temperature of 80°C for 80 minutes. The viscosity of the material was observed using an online viscometer. When the viscosity of the material reached 7500 mPa·s, the cooling was immediately started. The temperature was lowered to 25°C, and the viscosity of the material was measured again. It was 14000 mPa·s. The polystyrene (p-PS) prepared in this step was named A2.

[0028] Weigh divinylbenzene and styrene monomers at a mass ratio of 0.30:1 and mix them thoroughly. At the same time, add cumene hydroperoxide (CHP) at a mass ratio of 5% of the sum of divinylbenzene and styrene and mix thoroughly and evenly. The resulting mixture is named A3.

[0029] Mix A1 and A2 in a mixing tank at a mass ratio of 0.24:1 until homogeneous. The viscosity at 25 degrees Celsius is 13500±100 mPa·s. If the viscosity value exceeds this range, add a certain amount of A3 for final viscosity adjustment. This step requires strict control of the material viscosity to prepare for subsequent extrusion and casting. The final mixture formed in this process is named A4.

[0030] The A4 material is placed into a 1000*1000*100mm square mold using an extrusion casting unit. Pressure is applied to slowly extrude the material and evenly fill the entire mold cavity. Then, according to a specific temperature control program, the material is heated and cured. After demolding, high-performance polystyrene material can be obtained. Example 3

[0031] 168 kg of divinylbenzene monomer was weighed and placed in a reactor. Then, azobisisobutyronitrile (AIBN) was added, accounting for 2.25% of the mass of divinylbenzene. High-purity nitrogen was introduced into the reactor for gas protection. The equipment was started to carry out a thermal prepolymerization reaction at a polymerization temperature of 62°C for 70 minutes. The viscosity of the material was observed by an online viscometer. When the viscosity of the material reached 450 mPa·s, the cooling was started immediately. The temperature was lowered to 25°C, and the viscosity of the material was measured again to be approximately 1010 mPa·s. The polyvinylbenzene prepolymer (p-PDVB) prepared in this step was named A1.

[0032] 280 kg of styrene monomer was weighed and placed in a reactor. Benzoyl peroxide (BPO) with a mass fraction of 2.5% of styrene was then added. High-purity nitrogen was introduced into the reactor for gas protection. The equipment was started to carry out a thermal prepolymerization reaction at a polymerization temperature of 82°C for 75 minutes. The viscosity of the material was observed using an online viscometer. When the viscosity of the material reached 6700 mPa·s, the cooling process was immediately initiated. The temperature was lowered to 25°C, and the viscosity of the material was measured again to be 16100 mPa·s. The polystyrene prepolymer (p-PS) prepared in this step was named A2.

[0033] Weigh divinylbenzene and styrene monomers at a mass ratio of 0.25:1 and mix them thoroughly. At the same time, add cumene hydroperoxide (CHP) at a mass ratio of 5% of the sum of divinylbenzene and styrene and mix thoroughly and evenly. The mixture formed in this process is named A3.

[0034] Mix A1 and A2 in a mixing tank at a mass ratio of 0.32:1 until homogeneous. The viscosity at 25 degrees Celsius is 15500±100 mPa·s. If the viscosity value exceeds this range, add a certain amount of A3 for final viscosity adjustment. This step requires strict control of the material viscosity to prepare for subsequent extrusion and casting. The final mixture is named A4.

[0035] The A4 material is placed into a 1500*1500*200mm square mold using an extrusion casting unit. Pressure is applied to slowly extrude the material and evenly fill the entire mold cavity. Then, according to a specific temperature control program, the material is heated and cured. After demolding, high-performance polystyrene material can be obtained.

[0036] Compare with Example 1: Weigh 120 kg of styrene monomer and place it in a reactor. Then add benzoyl peroxide (BPO) at a mass fraction of 2.5% of styrene. Purge the reactor with high-purity nitrogen for gas protection. Start the equipment for thermal prepolymerization reaction at a polymerization temperature of 79°C for 85 minutes. Observe the viscosity of the material using an online viscometer. When the viscosity of the material reaches 7500 mPa·s, immediately start cooling. Cool down to 25°C and measure the viscosity of the material again. The viscosity is 16800 mPa·s. Place the polystyrene prepolymer (p-PS) prepared in this step into a 1000*1000*100 mm square mold using an extrusion casting unit. Apply pressure to slowly extrude the material and evenly fill the entire mold cavity. Then, follow a specific temperature control program to heat up and cure the material. Demolding yields the material.

[0037] Compare with Example 2: 120 kg of styrene monomer was weighed and placed in a reactor. Benzoyl peroxide (BPO) was added, accounting for 2.5% of the styrene mass. High-purity nitrogen was introduced into the reactor for gas protection. The equipment was started for a thermal prepolymerization reaction at 79°C for 85 minutes. The viscosity of the material was observed using an online viscometer. When the viscosity reached 7500 mPa·s, cooling was immediately initiated. The temperature was lowered to 25°C, and the viscosity was measured again to be 16800 mPa·s. Divinylbenzene crosslinking agent monomer was added to the polystyrene prepolymer (p-PS) prepared in this step, at a dosage of 1% of the total prepolymer. The viscosity at this point was approximately 16500 ± 100 mPa·s. The mixture was then placed into a 1000*1000*100 mm square mold using an extrusion casting unit. Pressure was applied to slowly extrude the material and evenly fill the entire mold cavity. Then, the material was cured according to a specific temperature control program. After demolding, the material was obtained.

[0038] Compare with Example 3: 120 kg of styrene monomer was weighed and placed in a reactor. Benzoyl peroxide (BPO) was added, accounting for 2.5% of the styrene mass. High-purity nitrogen was introduced into the reactor for gas protection. The equipment was started for a thermal prepolymerization reaction at 79°C for 85 minutes. The viscosity of the material was observed using an online viscometer. When the viscosity reached 7500 mPa·s, cooling was immediately initiated. The temperature was lowered to 25°C, and the viscosity was measured again to be 16800 mPa·s. Divinylbenzene crosslinking agent monomer was added to the polystyrene prepolymer (p-PS) prepared in this step, at a dosage of 32% of the total prepolymer. The viscosity at this point was approximately 15100 ± 100 mPa·s. The material was then placed into a 1000*1000*100 mm square mold using an extrusion casting unit. Pressure was applied to slowly extrude the material and evenly fill the entire mold cavity. Then, the material was cured according to a specific temperature control program. After demolding, the material was obtained.

[0039] The appearance analysis and performance tests were performed on Examples 1 to 3 and Comparative Examples 1 to 3. The test results are as follows: Example 1 No internal air bubbles, smooth outer surface 109 36 107 easy Example 2 No internal air bubbles, smooth outer surface 126 43 118 easy Example 3 No internal air bubbles, smooth outer surface 125 45 116 easy Compare with Example 1 No internal air bubbles, smooth outer surface 85 22 68 easy Compare with Example 2 White particles appeared inside / / / Cannot form a complete board Compare with Example 3- No internal air bubbles, smooth outer surface 118 18 131 It is difficult, requires precise control of the molding process, and carries a high risk of failure. The table above shows that when the crosslinking agent content is low, the material's mechanical strength is actually worse than when no crosslinking agent is added. White particles and cavities appear inside the material during polymerization, leading to material performance failure. Conversely, when the crosslinking agent content is high, the material becomes brittle, and its mechanical strength also decreases. Therefore, prepolymerizing divinylbenzene first reduces its heat release during the polystyrene molding process, lowering the risk of thermal runaway polymerization in large-size polystyrene materials and increasing the difficulty of controlling the molding process. Adding divinylbenzene further enhances the mechanical strength of the polystyrene material.

[0040] In this article, terms such as "up," "down," "front," "back," "left," and "right" are used only to indicate the relative positional relationship between related parts, rather than to define the absolute position of these related parts.

[0041] The above technical features constitute the embodiments of this application, which have strong adaptability and implementation effect. Non-essential technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A process and molding method for producing large size high performance polystyrene materials, characterized in that Includes the following steps: Step 1: Place a certain amount of divinylbenzene monomer in a reactor, and then add an initiator accounting for 1% to 6% of the mass fraction of divinylbenzene; carry out a prepolymerization reaction to obtain a polydivinylbenzene prepolymer with a set viscosity, and name it A1; Step 2: Place a certain amount of styrene monomer in a reactor, and add an initiator accounting for 2.5% to 10% of the styrene mass fraction; carry out a prepolymerization reaction to obtain a polystyrene prepolymer with a set viscosity, and name it A2; Step 3: Take a certain amount of divinylbenzene and styrene monomer and mix them thoroughly. At the same time, add an initiator to fully dissolve and mix them evenly. The resulting mixture is named A3. Step 4: Mix A1 and A2 evenly in a mixing tank, then add A3 to adjust and control the viscosity, and name the resulting mixture A4. Heat and cure A4 to obtain high-performance polystyrene material.

2. The process and molding method for preparing large-size high-performance polystyrene materials according to claim 1, characterized in that: The initiator is one or a combination of several of azobisisobutyronitrile, benzoyl peroxide, and cumene hydroperoxide.

3. The process and molding method for preparing large-size high-performance polystyrene materials according to claim 1 or 2, characterized in that: In step 3, divinylbenzene and styrene monomers are thoroughly mixed at a mass ratio of 0.25:1 to 0.4:

1.

4. The process and molding method for preparing large-size high-performance polystyrene materials according to claim 1 or 2, characterized in that: In step 4, A1 and A2 are mixed evenly in a mixing tank at a mass ratio of 0.15:1 to 0.35:

1.

5. The process and molding method for preparing large-size high-performance polystyrene materials according to claim 3, characterized in that: In step 4, A1 and A2 are mixed evenly in a mixing tank at a mass ratio of 0.15:1 to 0.35:

1.

6. The process and molding method for preparing large-size high-performance polystyrene materials according to claim 1 or 2, characterized in that: In step 1, high-purity nitrogen gas is introduced into the reactor for gas protection to carry out the prepolymerization reaction. The polymerization temperature is 60℃ to 74℃ and the polymerization time is 45 minutes to 90 minutes. After the material reaches the set viscosity, it is cooled to 20℃ to 25℃ by observing the material through an online viscometer.

7. The process and molding method for preparing large-size high-performance polystyrene materials according to claim 5, characterized in that: In step 1, high-purity nitrogen gas is introduced into the reactor for gas protection to carry out the prepolymerization reaction. The polymerization temperature is 60℃ to 74℃ and the polymerization time is 45 minutes to 90 minutes. After the material reaches the set viscosity, it is cooled to 20℃ to 25℃ by observing the material through an online viscometer.

8. The process and molding method for preparing large-size high-performance polystyrene materials according to claim 1 or 2, characterized in that: In step 2, high-purity nitrogen gas is introduced into the reactor for gas protection to carry out the prepolymerization reaction. The polymerization temperature is 78℃ to 82℃, and the polymerization time is 90 minutes to 120 minutes. After the material reaches the set viscosity, it is cooled to 20℃ to 25℃ by observing the material through an online viscometer.

9. The process and molding method for preparing large-size high-performance polystyrene materials according to claim 5, characterized in that: In step 2, high-purity nitrogen gas is introduced into the reactor for gas protection to carry out the prepolymerization reaction. The polymerization temperature is 78℃ to 82℃, and the polymerization time is 90 minutes to 120 minutes. After the material reaches the set viscosity, it is cooled to 20℃ to 25℃ by observing the material through an online viscometer.

10. The process and molding method for preparing large-size high-performance polystyrene materials according to claim 7, characterized in that: In step 2, high-purity nitrogen gas is introduced into the reactor for gas protection to carry out the prepolymerization reaction. The polymerization temperature is 78℃ to 82℃, and the polymerization time is 90 minutes to 120 minutes. After the material reaches the set viscosity, it is cooled to 20℃ to 25℃ by observing the material through an online viscometer.