Preparation method of environment-friendly noise-reducing pmi foamed plastic

Abstract

The invention relates to the field of foamed plastic preparation, in particular to an environment-friendly noise-reducing pmi foamed plastic preparation method which comprises the following steps: 1, mixing a polybenzimidazole monomer, a catalyst and a polar solvent according to an optimal ratio of 4: 1: 2, and carrying out polymerization reaction under the conditions of the temperature of 180-250 DEG C and the pressure of 0.5-1.5 MPa to form a PMI resin prepolymer, in the reaction process, a proper amount of a noise reduction auxiliary agent is added at 200 DEG C to promote the noise reduction effect of the foam material. The environment-friendly raw materials are adopted, the specific catalyst (sodium chloride, ammonium chloride and the like), the foaming agent (azodicarbonamide) and the surfactant (lauryl sodium sulfate) are utilized, the raw materials show the characteristics of low toxicity and harmlessness in production and final products, the modern environment-friendly requirement is met, the influence on the environment is reduced, and the environment-friendly and environment-friendly foaming agent is suitable for industrial production. Therefore, the problem that a PMI foam material with excellent noise reduction performance is difficult to prepare by an existing noise reduction pmi foam plastic preparation method is solved.

Description

Technical Field

[0001] The invention belongs to the field of foam plastic preparation, and in particular relates to a method for preparing environmentally friendly noise-reducing PMI foam plastic. Background Art

[0002] PMI foam plastics are widely used in aerospace, automotive industry, construction and other fields due to their excellent thermal stability, low density and strong mechanical properties.

[0003] However, the traditional PMI foam plastic production process usually requires the use of harmful chemicals or high-energy consumption processes, which puts certain pressure on the environment. The existing noise-reducing PMI foam plastic preparation method is difficult to prepare PMI foam materials with excellent noise reduction performance, and it is impossible to obtain foam materials with strong high-temperature stability, high compressive strength and low density characteristics, which needs further improvement.

[0004] Therefore, an environmentally friendly noise-reducing PMI foam plastic preparation method is proposed, which can prepare PMI foam materials with excellent noise reduction performance and obtain foam materials with strong high-temperature stability, high compressive strength and low density. Summary of the Invention

[0005] In order to overcome the difficulty in preparing PMI foam materials with excellent noise reduction performance and the problem that foam materials with strong high-temperature stability, high compressive strength and low density properties cannot be obtained, an environmentally friendly noise reduction PMI foam preparation method is proposed.

[0006] The technical solution of the present invention is: a method for preparing an environmentally friendly noise-reducing PMI foam plastic. The raw materials used are polybenzimidazole monomer, catalyst, foaming agent, surfactant, polar solvent, noise reduction additive and other additives. The amount of each component is as follows: polybenzimidazole monomer (PMI monomer): 50-100 parts, catalyst: 1-5 parts, foaming agent: 2%-5%, surfactant: 0.5%-1%, polar solvent: 50-150 parts, noise reduction additive: 0.5-3 parts, other additives: 0-5 parts. The preparation method comprises the following steps:

[0007] Step 1: Polybenzimidazole monomer, catalyst, and polar solvent are mixed in an optimal ratio of 4:1:2 and polymerized at a temperature of 180-250 degrees Celsius and a pressure of 0.5-1.5 MPa to form a PMI resin prepolymer. During the reaction, an appropriate amount of noise reduction additive is added at 200 degrees Celsius to enhance the noise reduction effect of the foam material, thereby giving the resulting foam material excellent noise absorption performance.

[0008] Step 2: Add appropriate amounts of foaming agent, surfactant and other necessary additives to the mixture of polybenzimidazole monomer, catalyst and polar solvent in the optimal ratio of 4:1:2;

[0009] Step 3: The polymerization reaction is carried out at a temperature of 180-250 degrees Celsius and a pressure of 0.5-1.5 MPa. During the reaction, the viscosity of the system is adjusted to ensure the stability of the reaction system by appropriate stirring (the stirring speed is controlled at 100-300 rpm, and the stirring time is adjusted according to the progress of the reaction) and cooling operation (using a circulating water cooling system to maintain the temperature fluctuation of the reaction system within ±5 degrees Celsius). After the reaction reaches a predetermined stage, stirring is continued and the pressure is slowly released to fully introduce the gas in the system to form a foam precursor solution. At this time, the PMI foam precursor solution has good uniformity, and the bubbles are evenly distributed and small;

[0010] Step 4: Prepare a mold preheated to 160-170 degrees Celsius, and pour the foam precursor solution into the mold quickly and evenly. Then, the free foaming process begins immediately.

[0011] Step 5: At the initial stage of foaming, the temperature and pressure conditions inside the mold are maintained at 160-170 degrees Celsius and normal pressure to guide the initial expansion of the foam;

[0012] Step 6: As the foaming progresses, gradually lower the temperature inside the mold to room temperature and increase the pressure to slow down the expansion of the foam, allowing the bubbles enough time to merge and stabilize, thereby forming a uniform and dense pore structure;

[0013] Step 7: When the bubble wall is strong enough to withstand external pressure and maintain a stable pore structure, open the mold and take out the finished foam;

[0014] Step 8: Preliminary curing of the foam intermediate at room temperature for 1-2 hours, placing the preliminarily cured foam intermediate in a vacuum oven and performing high-temperature vacuum curing treatment at a temperature range of 150°C to 250°C. After baking for 4-6 hours, the foam material will undergo sufficient imidization reaction and curing process, thereby forming a stable high-performance PMI foam plastic;

[0015] Step 9: After baking, slowly lower the temperature in the oven to avoid internal stress or cracks in the foam material due to rapid cooling. The temperature should not exceed 50°C per hour until it reaches room temperature. Then test the foam material and package it for storage after passing the inspection.

[0016] Preferably, the catalyst comprises a combination of any one or more of sodium chloride, ammonium chloride, potassium chloride, sodium hydroxide and ammonium hydroxide, with a mass ratio of sodium chloride: ammonium chloride: potassium chloride: sodium hydroxide: ammonium hydroxide being 0.5-2: 0.5-2: 0.5-2: 0.1-0.5: 0.1-0.5.

[0017] Preferably, the foaming agent is azodicarbonamide (AC), and its mass ratio is 2% to 5% of the mass of the polybenzimidazole monomer.

[0018] Preferably, the surfactant is sodium dodecyl sulfate (SDS), and its mass ratio is 0.5% to 1% of the mass of the polybenzimidazole monomer.

[0019] Preferably, the polar solvent includes any one or more combinations of dimethylformamide (DMF), N-methylpyrrolidone (NMP) and alcohol solvents, with a mass ratio of dimethylformamide: N-methylpyrrolidone: alcohol solvent being 50-150 parts: 50-150 parts: 50-150 parts.

[0020] Preferably, the noise reduction agent is a combination of any one or more of a sound absorbing agent, an anti-vibration agent, a sound insulating agent and a sound wave reflecting agent, and the mass ratio is: sound absorbing agent: anti-vibration agent: sound insulating agent: sound wave reflecting agent is 0.5-3:0.5-3:0.5-3:0.5-3.

[0021] Preferably, the other additives include any one or more of antioxidants, plasticizers, stabilizers and toughening agents, with the mass ratio of antioxidant: plasticizer: stabilizer: toughening agent being 0-2:0-2:0-2:0-2.

[0022] Preferably, the foam material is formed at a pressure of 0.5-1.5 MPa, a temperature of 180-250° C., and a stirring speed of 100-300 rpm.

[0023] Preferably, the test items include physical and chemical properties, microbial indicators, content of exhaust gas components after combustion, compressive strength, sound absorption coefficient, thermal conductivity and weather resistance, etc.

[0024] Beneficial effects of the present invention:

[0025] 1. This method uses environmentally friendly raw materials, specific catalysts (sodium chloride, ammonium chloride, etc.), foaming agents (azodicarbonamide) and surfactants (sodium lauryl sulfate). These raw materials show low toxicity and harmlessness in production and final products, meet modern environmental protection requirements, and help reduce the impact on the environment, thereby solving the problem that the existing noise reduction PMI foam plastic preparation method is difficult to prepare PMI foam materials with excellent noise reduction performance;

[0026] 2. By adding specially designed noise reduction additives (sound absorbers, anti-vibration agents, sound insulation agents, sound wave reflectors, etc.) and optimizing parameter control during the preparation process, the PMI foam plastic has excellent noise absorption and insulation capabilities, making it suitable for various occasions where noise pollution needs to be reduced, such as transportation, building sound insulation, electronic equipment and other fields. This solves the problem that existing noise reduction PMI foam plastic preparation methods are difficult to prepare PMI foam materials with excellent noise reduction performance and cannot obtain foam materials with strong high-temperature stability;

[0027] 3. After high-temperature vacuum curing treatment, the foam material not only has high strength and good compressive resistance, but also exhibits excellent thermal stability and chemical inertness. It can maintain stable performance in a wide temperature range and is suitable for a variety of extreme environments, thus solving the problem that the existing noise reduction PMI foam plastic preparation method is difficult to obtain foam materials with strong high-temperature stability, high compressive strength and low density characteristics;

[0028] 4. Through precisely controlled foaming and curing processes, the foam material forms a uniform and dense pore structure, which not only improves the overall strength of the material, but also optimizes its acoustic properties, making sound absorption and reflection more efficient. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the embodiments.

[0030] Example 1: The present invention provides an embodiment: a method for preparing an environmentally friendly noise-reducing PMI foam plastic, the preparation method comprising the following steps:

[0031] Step 1: Weigh the following raw materials by mass: 50 parts PMI monomer, 2 parts catalyst (sodium chloride: ammonium chloride: potassium chloride: sodium hydroxide: ammonium hydroxide in a mass ratio of 1:1:1:0.3:0.3), and 100 parts dimethylformamide (DMF). Mix these materials and polymerize them at 200°C and 1 MPa to form a PMI resin prepolymer. When the reaction reaches 200°C, add 1 part sound absorber as a noise reduction aid.

[0032] Step 2: Adding azodicarbonamide (AC) foaming agent in an amount of 3% of the mass of the PMI monomer and sodium dodecyl sulfate (SDS) surfactant in an amount of 0.6% of the mass of the PMI monomer to the prepolymer solution;

[0033] Step 3: Continue the polymerization reaction at 220 degrees Celsius and 1 MPa, maintain the system temperature stable by stirring (speed controlled at 200 rpm) and circulating water cooling, and slowly release the pressure after the reaction reaches a predetermined stage to form a foam precursor solution;

[0034] Step 4: Prepare a mold preheated to 150 degrees Celsius and pour the foam precursor solution into the mold quickly and evenly. Then, the free foaming process begins immediately.

[0035] Step 5: At the initial stage of foaming, the temperature and pressure conditions inside the mold are maintained at 150 degrees Celsius and normal pressure to guide the initial expansion of the foam;

[0036] Step 6: As the foaming progresses, gradually lower the temperature inside the mold to room temperature and increase the pressure to slow down the expansion of the foam, allowing the bubbles enough time to merge and stabilize, thereby forming a uniform and dense pore structure;

[0037] Step 7: When the bubble wall is strong enough to withstand external pressure and maintain a stable pore structure, open the mold and take out the finished foam;

[0038] Step 8: The foam intermediate was preliminarily cured at room temperature for 1.5 hours, and then placed in a vacuum oven and vacuum cured at 200°C for 5 hours;

[0039] Step 9: After baking, slowly cool down to room temperature, with a cooling rate of no more than 50°C per hour, and test the foam material, including physical and chemical properties, microbial indicators, content of exhaust gas components after combustion, compressive strength, sound absorption coefficient, thermal conductivity and weather resistance.

[0040] Example 2: Based on Example 1, the present invention provides an embodiment: a method for preparing an environmentally friendly noise-reducing PMI foam plastic, the preparation method comprising the following steps:

[0041] Step 1: Weigh the raw materials according to the mass ratio: 75 parts of PMI monomer, 3 parts of catalyst (sodium chloride: ammonium chloride: potassium chloride: sodium hydroxide: ammonium hydroxide mixed in a mass ratio of 0.5:2:2:0.5:0.5), 75 parts of N-methylpyrrolidone (NMP), and 25 parts of alcohol solvent, and carry out polymerization reaction at 230 degrees Celsius and 1.2 MPa. Add 1 part each of sound absorber and anti-vibration agent as noise reduction aids;

[0042] Steps 2 to 3: Add AC foaming agent (4% by mass of the PMI monomer) and SDS surfactant (0.8% by mass of the PMI monomer), and continue polymerization at 230°C and 1.2 MPa with a stirring speed of 250 rpm.

[0043] Step 4: Prepare a mold preheated to 160-170 degrees Celsius, and pour the foam precursor solution into the mold quickly and evenly. Then, the free foaming process begins immediately.

[0044] Step 5: At the initial stage of foaming, the temperature and pressure conditions inside the mold are maintained at 160-170 degrees Celsius and normal pressure to guide the initial expansion of the foam;

[0045] Step 6: As the foaming progresses, gradually lower the temperature inside the mold to room temperature and increase the pressure to slow down the expansion of the foam, allowing the bubbles enough time to merge and stabilize, thereby forming a uniform and dense pore structure;

[0046] Step 7: When the bubble wall is strong enough to withstand external pressure and maintain a stable pore structure, open the mold and take out the finished foam;

[0047] Step 8: Foaming and molding are performed according to the method of Example 1, except that the mold is preheated to 170 degrees Celsius, and then cured for 2 hours, followed by vacuum curing at 220 degrees Celsius for 4.5 hours;

[0048] Step 9: Slowly cool to room temperature, and the test items are the same as those in Example 1.

[0049] Example 3: Based on Example 1 and Example 2, the present invention provides an embodiment: a method for preparing an environmentally friendly noise-reducing PMI foam plastic, the preparation method comprising the following steps:

[0050] Step 1: Weigh the raw materials according to the mass ratio: 100 parts of PMI monomer, 5 parts of catalyst (all ammonium chloride), 75 parts of DMF and 75 parts of NMP as polar solvents, carry out polymerization reaction at 250 degrees Celsius and 1.5 MPa, and add 1.5 parts of sound absorbing agent and sound insulating agent as noise reduction agents;

[0051] Steps 2 to 3: Adding AC foaming agent at a mass of 5% of the mass of the PMI monomer and SDS surfactant at a mass of 1% of the mass of the PMI monomer, and continuing polymerization at 250 degrees Celsius and 1.5 MPa, with the stirring speed controlled at 300 rpm;

[0052] Steps 4 to 7: Foaming and molding are performed according to the method of Example 1, but the pressure in the mold is slightly adjusted to a slight negative pressure during the initial foaming stage;

[0053] Step 8: Curing treatment: initial curing for 1 hour, followed by vacuum curing at 150°C for 6 hours to explore the effect of low-temperature and long-term curing;

[0054] Step 9: Slowly cool to room temperature, and the test items are the same as those in Example 2.

[0055]

[0056]

[0057]

[0058] Through the above steps, the present invention uses environmentally friendly raw materials such as polybenzimidazole monomer, sodium chloride, ammonium chloride, and low-toxic, harmless foaming agents and surfactants such as azodicarbonamide and sodium lauryl sulfate. These raw materials exhibit good environmental properties in production and in the final product, meet modern environmental protection requirements, help reduce the impact on the environment, and embody the green and sustainable development concept of the present invention.

[0059] By adding specially designed noise reduction additives, such as sound absorbers, anti-vibration agents, sound insulation agents, and sound wave reflectors, and optimizing parameter control during the preparation process, the present invention successfully produces PMI foam plastics with excellent noise absorption and insulation capabilities. This material is suitable for various occasions where noise pollution needs to be reduced, such as transportation, building sound insulation, electronic equipment, and other fields, and can effectively improve people's living environment and working conditions.

[0060] After high-temperature vacuum curing, the PMI foam plastic prepared by the present invention not only has high strength and good compressive resistance, but also exhibits excellent thermal stability and chemical inertness. This material can maintain stable performance over a wide temperature range and is suitable for a variety of extreme environments, such as high temperature, high pressure, and severe corrosion, showing its wide application potential.

[0061] Through precisely controlled foaming and curing processes, the PMI foam plastic prepared by the present invention forms a uniform and dense pore structure. This structure not only improves the overall strength of the material, but also optimizes its acoustic properties, making sound absorption and reflection more efficient. This characteristic gives PMI foam plastic a wider application prospect in the field of acoustics, thereby solving the problem that existing noise-reducing PMI foam plastic preparation methods are difficult to prepare PMI foam materials with excellent noise reduction properties and are unable to obtain foam materials with strong high-temperature stability, high compressive strength and low density.

Claims

1. A method for preparing environmentally friendly noise-reducing PMI foam plastics, characterized by: The raw materials used are polybenzimidazole monomer, catalyst, foaming agent, surfactant, polar solvent, noise reduction agent and other additives. The amounts of each component are as follows: polybenzimidazole monomer (PMI monomer): 50-100 parts, catalyst: 1-5 parts, foaming agent: 2%-5%, surfactant: 0.5%-1%, polar solvent: 50-150 parts, noise reduction agent: 0.5-3 parts, other additives: 0-5 parts. The preparation method comprises the following steps: Step 1: Polybenzimidazole monomer, catalyst, and polar solvent are mixed in an optimal ratio of 4:1:2 and polymerized at a temperature of 180-250 degrees Celsius and a pressure of 0.5-1.5 MPa to form a PMI resin prepolymer. During the reaction, an appropriate amount of noise reduction additive is added at 200 degrees Celsius to enhance the noise reduction effect of the foam material, thereby giving the resulting foam material excellent noise absorption performance. Step 2: In a mixture of polybenzimidazole monomer, catalyst and polar solvent in an optimal ratio of 4:1:2, Add appropriate amount of foaming agent, surfactant and other necessary additives; Step 3: The polymerization reaction is carried out at a temperature of 180-250 degrees Celsius and a pressure of 0.5-1.5 MPa. During the reaction, the viscosity of the system is adjusted to ensure the stability of the reaction system by appropriate stirring (the stirring speed is controlled at 100-300 rpm, and the stirring time is adjusted according to the progress of the reaction) and cooling operation (using a circulating water cooling system to maintain the temperature fluctuation of the reaction system within ±5 degrees Celsius). After the reaction reaches a predetermined stage, stirring is continued and the pressure is slowly released to fully introduce the gas in the system to form a foam precursor solution. At this time, the PMI foam precursor solution has good uniformity, and the bubbles are evenly distributed and small; Step 4: Prepare a mold preheated to 160-170 degrees Celsius, and pour the foam precursor solution into the mold quickly and evenly. Then, the free foaming process begins immediately. Step 5: At the initial stage of foaming, the temperature and pressure conditions inside the mold are maintained at 160-170 degrees Celsius and normal pressure to guide the initial expansion of the foam; Step 6: As the foaming progresses, gradually lower the temperature inside the mold to room temperature and increase the pressure to slow down the expansion of the foam, allowing the bubbles enough time to merge and stabilize, thereby forming a uniform and dense pore structure; Step 7: When the bubble wall is strong enough to withstand external pressure and maintain a stable pore structure, open the mold and take out the finished foam; Step 8: Preliminary curing of the foam intermediate at room temperature for 1-2 hours, placing the preliminarily cured foam intermediate in a vacuum oven and performing high-temperature vacuum curing treatment at a temperature range of 150°C to 250°C. After baking for 4-6 hours, the foam material will undergo sufficient imidization reaction and curing process, thereby forming a stable high-performance PMI foam plastic; Step 9: After baking, slowly lower the temperature in the oven to avoid internal stress or cracks in the foam material due to rapid cooling. The temperature should not exceed 50°C per hour until it reaches room temperature. Then test the foam material and package it for storage after passing the inspection.

2. The method for preparing environmentally friendly noise-reducing PMI foam plastic according to claim 1, characterized in that: The catalyst comprises any one or more combinations of sodium chloride, ammonium chloride, potassium chloride, sodium hydroxide and ammonium hydroxide, with a mass ratio of sodium chloride:ammonium chloride:potassium chloride:sodium hydroxide:ammonium hydroxide being 0.5-2:0.5-2:0.5-2:0.1-0.5:0.1-0.

5.

3. The method for preparing environmentally friendly noise-reducing PMI foam plastic according to claim 1, characterized in that: The foaming agent is azodicarbonamide (AC), and its mass ratio is 2% to 5% of the mass of the polybenzimidazole monomer.

4. The method for preparing environmentally friendly noise-reducing PMI foam plastic according to claim 1, characterized in that: The surfactant is sodium dodecyl sulfate (SDS), and its mass ratio is 0.5% to 1% of the mass of the polybenzimidazole monomer.

5. The method for preparing environmentally friendly noise-reducing PMI foam plastic according to claim 1, characterized in that: The polar solvent includes any one or more combinations of dimethylformamide (DMF), N-methylpyrrolidone (NMP) and alcohol solvents, with a mass ratio of dimethylformamide: N-methylpyrrolidone: alcohol solvent being 50-150 parts: 50-150 parts: 50-150 parts.

6. The method for preparing environmentally friendly noise-reducing PMI foam plastic according to claim 1, characterized in that: The noise reduction agent is a combination of any one or more of a sound absorbing agent, an anti-vibration agent, a sound insulating agent and a sound wave reflecting agent, and the mass ratio is: sound absorbing agent: anti-vibration agent: sound insulating agent: sound wave reflecting agent is 0.5-3:0.5-3:0.5-3:0.5-3.

7. The method for preparing environmentally friendly noise-reducing PMI foam plastic according to claim 1, characterized in that: The other additives include any one or more of antioxidants, plasticizers, stabilizers and toughening agents, and the mass ratio of antioxidant: plasticizer: stabilizer: toughening agent is 0-2:0-2:0-2:0-2.

8. The method for preparing environmentally friendly noise-reducing PMI foam plastic according to claim 1, characterized in that: The foam material is formed under a pressure of 0.5-1.5 MPa, a temperature of 180-250° C., and a stirring speed of 100-300 rpm.

9. The method for preparing environmentally friendly noise-reducing PMI foam plastic according to claim 1, characterized in that: The test items include physical and chemical properties, microbial indicators, content of exhaust gas components after combustion, compressive strength, sound absorption coefficient, thermal conductivity and weather resistance.

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