Method for preparing polystyrene through suspension polymerization
The suspension polymerization method adds hydrotalcite and graphite to polystyrene to form a protective film, which solves the problem of poor flame retardancy of polystyrene and significantly improves its flame retardant performance.
Patent Information
- Application Number
- CN202510094423.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-21
- Publication Date
- 2025-04-15
AI Technical Summary
Polystyrene has poor flame retardancy and is prone to produce combustible small molecules and continue to burn during the combustion process.
Polystyrene is prepared by suspended polymerization, and hydrotalcite and graphite prepared by adding raw materials such as cobalt trioxide, magnesium oxide, cerium nitrate, aluminum nitrate, etc. to form a dense protective film to prevent the transfer of oxygen and heat.
It significantly improves the flame retardancy of polystyrene, inhibits the release of combustible gases and the transfer of heat, and ensures the application safety of polystyrene.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of polymers, and in particular to a method for preparing polystyrene by suspension polymerization. Background Art
[0002] Polystyrene is a polymer compound formed by the polymerization of styrene monomers. As a widely used plastic, it has good insulation and processing properties, and plays an important role in many fields such as packaging, electronics, and construction. However, the molecular structure of polystyrene is mainly composed of carbon-carbon single bonds and benzene rings. The bond energy of the chemical bonds in this structure is relatively low, and it is very easy to break when encountering a fire source, producing a large number of flammable small molecules, such as hydrocarbon free radicals. Although the benzene ring has a certain stability, during the combustion process, after the CH bonds around the benzene ring structure break, the benzene ring will also participate in the combustion reaction. In addition, the molecular chain of polystyrene is relatively regular, and there is no special chemical structure that can hinder the combustion reaction. This makes it easy to continue once the combustion is initiated. Therefore, it is necessary to obtain a polystyrene with excellent flame retardancy. Summary of the invention
[0003] The invention provides a method for preparing polystyrene by suspension polymerization, which solves the problem of poor flame retardancy of polystyrene in the related art.
[0004] The technical solution of the present invention is as follows: The present invention provides a method for preparing polystyrene by suspension polymerization, comprising the following steps: S1, mixing a dispersant and water to obtain a mixed solution; S2, mixing cobalt trioxide, magnesium oxide, cerium nitrate, aluminum nitrate and nitric acid solution for the first time, adjusting the pH to 9-10, mixing for the second time, crystallizing, and post-treating to obtain hydrotalcite; S3, mixing the hydrotalcite, styrene and initiator, adding the mixture into the mixed solution for suspension polymerization, and drying to obtain polystyrene particles.
[0005] As a further technical solution, the mass of the initiator is 0.8% to 2% of the mass of the styrene; The mass of the dispersant is 4% to 8% of the mass of the styrene; The mass ratio of the styrene to the water is 1:1.5-2.
[0006] In the present invention, styrene is dispersed into tiny droplets in the water phase, and the initiator decomposes to generate free radicals, which trigger the polymerization reaction of styrene monomers in the small droplets, and gradually polymerize into polystyrene particles. The amounts of initiator, dispersant, water and styrene are kept within the scope of the present invention, which can ensure the smooth progress of suspension polymerization and the preparation of uniformly distributed polystyrene particles.
[0007] As a further technical solution, the initiator includes one or more of benzoyl peroxide, azobisisobutyronitrile, and tert-butyl perbenzoate; The dispersant includes a water-soluble organic dispersant.
[0008] In the present invention, the dispersant is a water-soluble organic dispersant, which has good hydrophilicity and dispersing ability, can reduce the oil-water interfacial tension, disperse styrene into uniform small droplets in the aqueous phase, stabilize the reaction system, and prevent the droplets from coalescing; wherein the water-soluble organic dispersant can be, for example, hydroxymethyl cellulose, polyvinyl alcohol, gelatin, sodium polymethacrylate, etc., preferably polyvinyl alcohol and gelatin.
[0009] As a further technical solution, in step S3, the suspension polymerization is carried out at a temperature of 85-100° C. for 3-8 hours.
[0010] As a further technical solution, the mass ratio of the cobalt trioxide, magnesium oxide, cerium nitrate and aluminum nitrate is 0.5~2:1:1:1.
[0011] In the present invention, cobalt trioxide, magnesium oxide, cerium nitrate and aluminum nitrate in a mass ratio of 0.5 to 2:1:1:1 are used as raw materials for preparing hydrotalcite. The raw materials cooperate with each other to achieve the best result, which can effectively regulate the crystal structure and chemical composition of the hydrotalcite and improve the flame retardancy of the polystyrene particles.
[0012] As a further technical solution, the volume fraction of the nitric acid solution is 1.5% to 2%; The mass volume ratio of the magnesium oxide to the nitric acid solution is 1 g: 3-5 mL; The mass of the hydrotalcite is 8% to 10% of the mass of the styrene.
[0013] As a further technical solution, in step S2, the temperature of the first mixing is 40-50°C and the time is 20-30 minutes; The second mixing temperature is 40-50°C and the time is 1-1.5h; The crystallization temperature is 80-90° C. and the crystallization time is 7-9 hours.
[0014] In the present invention, the mixing temperature during the preparation of the hydrotalcite is 40-50°C and the crystallization temperature is 80-90°C, which can make the layered structure of the hydrotalcite grow completely. When flame retardant, a stable barrier layer can be more effectively formed, and the release of combustible gas and the transfer of heat can be suppressed through interlayer adsorption and physical barrier, thereby ensuring the flame retardancy of polystyrene.
[0015] As a further technical solution, in step S3, graphite is added during the mixing to replace 15% to 25% of the mass of the hydrotalcite.
[0016] In the present invention, when preparing polystyrene, graphite is added to replace 15% to 25% of the mass of hydrotalcite. The synergy of graphite and hydrotalcite improves the flame retardancy of polystyrene and also improves the strength of polystyrene.
[0017] As a further technical solution, the post-treatment includes washing and drying treatments in sequence.
[0018] In the present invention, washing and drying are performed after the polystyrene is prepared by suspension polymerization to remove impurities and unreacted monomers in the polystyrene, thereby ensuring the quality and application stability of the polystyrene particles.
[0019] The invention also provides polystyrene, which is prepared by the method for preparing polystyrene by suspension polymerization.
[0020] The working principle and beneficial effects of the present invention are: In the present invention, styrene, an initiator, a dispersant and other components are used for suspension polymerization to prepare polystyrene. In the preparation process, hydrotalcite prepared from cobalt trioxide, magnesium oxide, cerium nitrate and aluminum nitrate as raw materials is added. During the combustion process, the hydrotalcite is thermally decomposed to absorb heat, which can reduce the surface temperature of the polystyrene. At the same time, substances such as metal oxides generated by the decomposition of the hydrotalcite can form a dense protective film on the surface of the polystyrene, prevent the transfer of oxygen and heat, and inhibit the generation of combustible gas, thereby improving the flame retardancy of the polystyrene. DETAILED DESCRIPTION
[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0022] In the following examples and comparative examples, the cerium nitrate is cerium nitrate hexahydrate, the aluminum nitrate is aluminum nitrate hexahydrate, the particle size of the hydrotalcite is 500 mesh, the particle size of the graphite is 3 μm, and the weight average molecular weight of the polyvinyl alcohol is 30,000.
[0023] Example 1 The method for preparing polystyrene by suspension polymerization comprises the following steps: S1, mixing gelatin and water to obtain a mixed solution; S2. Cobalt trioxide, magnesium oxide, cerium nitrate, aluminum nitrate and 1.5% nitric acid solution by volume are mixed at 40°C for 30 minutes, the pH value is adjusted to 9, the mixture is mixed at 40°C for 1.5 hours, crystallized at 80°C for 9 hours, washed and dried to obtain hydrotalcite; wherein the mass ratio of cobalt trioxide, magnesium oxide, cerium nitrate and aluminum nitrate is 2.5:1:1:1, and the mass volume ratio of magnesium oxide and nitric acid solution is 1 g:3 mL; S3, mixing hydrotalcite, styrene and benzoyl peroxide, adding the mixture to the mixed solution, performing suspension polymerization at 85° C. for 8 h, and drying to obtain polystyrene particles; Among them, the mass of benzoyl peroxide is 0.8% of the mass of styrene, the mass of gelatin is 4% of the mass of styrene, the mass ratio of styrene to water is 1:1.5, and the mass of hydrotalcite is 8% of the mass of styrene.
[0024] Example 2 The method for preparing polystyrene by suspension polymerization comprises the following steps: S1, mixing gelatin and water to obtain a mixed solution; S2. Mix cobalt trioxide, magnesium oxide, cerium nitrate, aluminum nitrate and 2% nitric acid solution at 50°C for 20 minutes, adjust the pH to 10, mix at 50°C for 1 hour, crystallize at 90°C for 7 hours, wash, and dry to obtain hydrotalcite; wherein the mass ratio of cobalt trioxide, magnesium oxide, cerium nitrate, and aluminum nitrate is 2.5:1:1:1, and the mass volume ratio of magnesium oxide to nitric acid solution is 1 g:5 mL; S3, mixing hydrotalcite, styrene and tert-butyl perbenzoate, adding the mixture to the mixed solution, performing suspension polymerization at 100° C. for 3 h, and drying to obtain polystyrene particles; Among them, the mass of benzoyl peroxide is 2% of the mass of styrene, the mass of gelatin is 8% of the mass of styrene, the mass ratio of styrene to water is 1:2, and the mass of hydrotalcite is 10% of the mass of styrene.
[0025] Example 3 The method for preparing polystyrene by suspension polymerization comprises the following steps: S1, mixing polyvinyl alcohol and water to obtain a mixed solution; S2. Cobalt trioxide, magnesium oxide, cerium nitrate, aluminum nitrate and 1.8% nitric acid solution are mixed at 45°C for 25 minutes, the pH is adjusted to 9.5, the mixture is mixed at 45°C for 1.5 hours, crystallized at 85°C for 8 hours, washed and dried to obtain hydrotalcite; wherein the mass ratio of cobalt trioxide, magnesium oxide, cerium nitrate and aluminum nitrate is 2.5:1:1:1, and the mass volume ratio of magnesium oxide and nitric acid solution is 1 g:4 mL; S3, mixing hydrotalcite, styrene and benzoyl peroxide, adding the mixture to the mixed solution, performing suspension polymerization at 90° C. for 6 h, and drying to obtain polystyrene particles; Among them, the mass of benzoyl peroxide is 1% of the mass of styrene, the mass of polyvinyl alcohol is 6% of the mass of styrene, the mass ratio of styrene to water is 1:1.8, and the mass of hydrotalcite is 9% of the mass of styrene.
[0026] Example 4 The only difference between this embodiment and embodiment 3 is that the mass ratio of cobalt trioxide, magnesium oxide, cerium nitrate and aluminum nitrate is 0.3:1:1:1.
[0027] Example 5 The only difference between this embodiment and embodiment 3 is that the mass ratio of cobalt trioxide, magnesium oxide, cerium nitrate and aluminum nitrate is 0.5:1:1:1.
[0028] Example 6 The only difference between this embodiment and embodiment 3 is that the mass ratio of cobalt trioxide, magnesium oxide, cerium nitrate and aluminum nitrate is 2:1:1:1.
[0029] Example 7 The method for preparing polystyrene by suspension polymerization comprises the following steps: S1, mixing polyvinyl alcohol and water to obtain a mixed solution; S2, cobalt trioxide, magnesium oxide, cerium nitrate, aluminum nitrate and 1.8% nitric acid solution were mixed at 45°C for 25 minutes, the pH was adjusted to 9.5, and then mixed at 45°C for 1.5 hours, crystallized at 85°C for 8 hours, washed, and dried to obtain hydrotalcite; wherein the mass ratio of cobalt trioxide, magnesium oxide, cerium nitrate, and aluminum nitrate was 2:1:1:1, and the mass volume ratio of magnesium oxide and nitric acid solution was 1g:4mL; S3, mixing graphite, hydrotalcite, styrene and benzoyl peroxide, adding the mixture to the mixed solution, performing suspension polymerization at 90° C. for 6 h, and drying to obtain polystyrene particles; Among them, the mass of benzoyl peroxide is 1% of the mass of styrene, the mass of polyvinyl alcohol is 6% of the mass of styrene, the mass ratio of styrene to water is 1:1.8, the total mass of hydrotalcite and graphite is 9% of the mass of styrene, and the mass ratio of graphite to hydrotalcite is 8:17.
[0030] Example 8 The only difference between this embodiment and embodiment 7 is that the mass ratio of graphite to hydrotalcite is 1:3.
[0031] Comparative Example 1 The method for preparing polystyrene by suspension polymerization comprises the following steps: S1, mixing polyvinyl alcohol and water to obtain a mixed solution; S2, magnesium oxide, cerium nitrate, aluminum nitrate and 1.8% nitric acid solution by volume are mixed at 45°C for 25 minutes, pH is adjusted to 9.5, mixed at 45°C for 1.5 hours, crystallized at 85°C for 8 hours, washed, and dried to obtain hydrotalcite; wherein the mass ratio of magnesium oxide, cerium nitrate, and aluminum nitrate is 3.5:1:1, and the mass volume ratio of magnesium oxide and nitric acid solution is 1g:4mL; S3, mixing hydrotalcite, styrene and benzoyl peroxide, adding the mixture to the mixed solution, performing suspension polymerization at 90° C. for 6 h, and drying to obtain polystyrene particles; Among them, the mass of benzoyl peroxide is 1% of the mass of styrene, the mass of polyvinyl alcohol is 6% of the mass of styrene, the mass ratio of styrene to water is 1:1.8, and the mass of hydrotalcite is 9% of the mass of styrene.
[0032] Comparative Example 2 The method for preparing polystyrene by suspension polymerization comprises the following steps: S1, mixing polyvinyl alcohol and water to obtain a mixed solution; S2, cobalt trioxide, magnesium oxide, aluminum nitrate and 1.8% nitric acid solution were mixed at 45°C for 25 minutes, pH was adjusted to 9.5, mixed at 45°C for 1.5 hours, crystallized at 85°C for 8 hours, washed, and dried to obtain hydrotalcite; wherein the mass ratio of cobalt trioxide, magnesium oxide, and aluminum nitrate was 2.5:1:2, and the mass volume ratio of magnesium oxide and nitric acid solution was 1g:4mL; S3, mixing hydrotalcite, styrene and benzoyl peroxide, adding the mixture to the mixed solution, performing suspension polymerization at 90° C. for 6 h, and drying to obtain polystyrene particles; Among them, the mass of benzoyl peroxide is 1% of the mass of styrene, the mass of polyvinyl alcohol is 6% of the mass of styrene, the mass ratio of styrene to water is 1:1.8, and the mass of hydrotalcite is 9% of the mass of styrene.
[0033] Comparative Example 3 The method for preparing polystyrene by suspension polymerization comprises the following steps: S1, mixing polyvinyl alcohol and water to obtain a mixed solution; S2, mixing magnesium oxide, aluminum nitrate and a nitric acid solution with a volume fraction of 1.8% at 45°C for 25 minutes, adjusting the pH to 9.5, mixing at 45°C for 1.5 hours, crystallizing at 85°C for 8 hours, washing, and drying to obtain hydrotalcite; wherein the mass ratio of magnesium oxide to aluminum nitrate is 3.5:2, and the mass volume ratio of magnesium oxide to nitric acid solution is 1g:4mL; S3, mixing hydrotalcite, styrene and benzoyl peroxide, adding the mixture to the mixed solution, performing suspension polymerization at 90° C. for 6 h, and drying to obtain polystyrene particles; Among them, the mass of benzoyl peroxide is 1% of the mass of styrene, the mass of polyvinyl alcohol is 6% of the mass of styrene, the mass ratio of styrene to water is 1:1.8, and the mass of hydrotalcite is 9% of the mass of styrene.
[0034] Comparative Example 4 The method for preparing polystyrene by suspension polymerization comprises the following steps: S1, mixing polyvinyl alcohol and water to obtain a mixed solution; S2, mixing graphite, styrene and benzoyl peroxide, adding the mixture to the mixed solution, performing suspension polymerization at 90° C. for 6 h, and drying to obtain polystyrene particles; Among them, the mass of benzoyl peroxide is 1% of the mass of styrene, the mass of polyvinyl alcohol is 6% of the mass of styrene, the mass ratio of styrene to water is 1:1.8, and the mass of graphite is 9% of the mass of styrene.
[0035] Experimental Example 1 The polystyrene particles obtained in Examples 1 to 8 and Comparative Examples 1 to 4 were extruded into sheets and then subjected to flame retardancy tests: The oxygen index of polystyrene was measured according to the standard GB / T 2406.2-2009 "Determination of combustion behavior of plastics by oxygen index method Part 2: Room temperature test", and the results are shown in Table 1 below.
[0036] Table 1 Performance test results
[0037] Compared with Comparative Examples 1 to 4, the oxygen index of the polystyrene particles obtained in Examples 1 to 8 is higher, indicating that the polystyrene is prepared by suspension polymerization using styrene, an initiator, a dispersant and other components, and hydrotalcite prepared using cobalt trioxide, magnesium oxide, cerium nitrate and aluminum nitrate as raw materials is added during the preparation process, and graphite is added for synergistic effect, thereby improving the flame retardancy of the polystyrene.
[0038] Experimental Example 2 The polystyrene particles obtained in Example 3, Examples 6 to 8 and Comparative Example 4 were respectively extruded into sheets and tested according to the standard GB / T 1040.1-2018 "Determination of tensile properties of plastics Part 1: General Principles", with a tensile rate of 5 mm / min. The results are shown in Table 2 below.
[0039] Table 2 Performance test results
[0040] Compared with Comparative Example 4, Example 3, and Example 6, the tensile strength of the polystyrene particles prepared in Examples 7-8 is higher, indicating that the hydrotalcite prepared in the present invention cooperates with graphite to improve the strength of polystyrene.
[0041] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for preparing polystyrene by suspension polymerization, characterized in that: The following steps are involved: S1, mixing a dispersant and water to obtain a mixed solution; S2, mixing cobalt trioxide, magnesium oxide, cerium nitrate, aluminum nitrate and nitric acid solution for the first time, adjusting the pH to 9-10, mixing for the second time, crystallizing, and post-treating to obtain hydrotalcite; S3, mixing the hydrotalcite, styrene and initiator, adding the mixture into the mixed solution for suspension polymerization, and drying to obtain polystyrene particles.
2. The method for preparing polystyrene by suspension polymerization according to claim 1, characterized in that: The mass of the initiator is 0.8% to 2% of the mass of the styrene; The mass of the dispersant is 4% to 8% of the mass of the styrene; The mass ratio of the styrene to the water is 1:1.5-2.
3. The method for preparing polystyrene by suspension polymerization according to claim 1, characterized in that: The initiator includes one or more of benzoyl peroxide, azobisisobutyronitrile, and tert-butyl perbenzoate; The dispersant includes a water-soluble organic dispersant.
4. The method for preparing polystyrene by suspension polymerization according to claim 1, characterized in that: In step S3, the suspension polymerization is carried out at a temperature of 85-100° C. for a time of 3-8 hours.
5. The method for preparing polystyrene by suspension polymerization according to claim 1, characterized in that: The mass ratio of the cobalt trioxide, magnesium oxide, cerium nitrate and aluminum nitrate is 0.5-2:1:1:
1.
6. The method for preparing polystyrene by suspension polymerization according to claim 1, characterized in that: The volume fraction of the nitric acid solution is 1.5% to 2%; The mass volume ratio of the magnesium oxide to the nitric acid solution is 1 g: 3-5 mL; The mass of the hydrotalcite is 8% to 10% of the mass of the styrene.
7. The method for preparing polystyrene by suspension polymerization according to claim 1, characterized in that: In step S2, the temperature of the first mixing is 40-50° C. and the time is 20-30 min; The second mixing temperature is 40-50°C and the time is 1-1.5h; The crystallization temperature is 80-90° C. and the crystallization time is 7-9 hours.
8. The method for preparing polystyrene by suspension polymerization according to claim 1, characterized in that: In step S3, graphite is added during the mixing to replace 15% to 25% of the mass of the hydrotalcite.
9. The method for preparing polystyrene by suspension polymerization according to claim 8, characterized in that: The post-treatment includes washing and drying in sequence.
10. A polystyrene, characterized in that: The polystyrene is prepared by the method for preparing polystyrene by suspension polymerization as described in any one of claims 1 to 9.