Flame-retardant smoke-suppressing polystyrene foam material and preparation method thereof

Abstract

The invention discloses a preparation method of a flame-retardant smoke-suppressing polystyrene foam material. Comprising the following raw materials in parts by weight: 100-120 parts of polystyrene resin, 12-24 parts of modified molybdenum trioxide, 4-8 parts of a processing aid, 5-7 parts of an antioxidant, 1-3 parts of a foaming aid and 5-10 parts of a foaming agent. The prepared polystyrene foaming material adopts a composite foaming system consisting of a foaming agent and a foaming aid, and has the characteristics of low density, light weight and good heat insulation performance; wherein the modified molybdenum trioxide has better compatibility with a polystyrene matrix, the agglomeration phenomenon is reduced, the influence on the mechanical properties of the material is reduced, the heat resistance, flame retardance and smoke suppression performance of the material can be greatly improved, and the performance is long and stable; therefore, the polystyrene foam material prepared by the invention is light in weight and good in heat insulation, has stable and efficient heat resistance, flame retardance and smoke suppression performance, and has important application value in the technical field of foam materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of foaming materials, and specifically relates to a flame-retardant and smoke-suppressing polystyrene foaming material and a preparation method thereof. Background Art

[0002] With the rapid development of modern industry and construction, expanded polystyrene (EPS) has been widely used in the fields of building insulation, packaging protection, cold chain logistics, etc. due to its excellent heat insulation, sound insulation performance and light weight characteristics. However, traditional polystyrene foaming materials have a significant defect in practical applications, with high flammability and the generation of a large amount of thick smoke and toxic gases such as carbon monoxide and hydrogen cyanide during combustion. These characteristics not only increase the fire risk but also pose a serious threat to the safety of personnel's lives. Therefore, how to improve the flame retardancy and smoke suppression performance of polystyrene foaming materials has become an important research topic.

[0003] Currently, the modification of polystyrene foaming materials is mainly achieved by adding flame retardants. Commonly used flame retardants include halogen-based flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants, and inorganic flame retardants, etc. Among them, halogen-based flame retardants were widely used due to their high-efficiency flame retardant effect, but they release a large amount of toxic gases and corrosive substances during combustion, which does not meet the environmental protection requirements, so they have gradually been phased out or restricted. In contrast, phosphorus-based and nitrogen-based flame retardants have lower toxicity and can effectively inhibit flame propagation, but they often require a high addition amount to achieve an ideal flame retardant effect, which may lead to a decrease in the mechanical properties of the material and an increase in production costs. In addition, inorganic flame retardants (such as aluminum hydroxide, magnesium hydroxide, etc.) are green and environmentally friendly, but due to poor compatibility with the polymer matrix, they easily lead to difficult material processing and deterioration of physical properties. In addition to the flame retardant performance, the thick smoke generated by polystyrene foaming materials during combustion is also an urgent problem to be solved. Smoke not only reduces the visibility for escape but also carries a variety of harmful components, causing direct harm to human health.

[0004] In summary, developing a polystyrene foaming material with high-efficiency flame retardancy, low smoke emission and good mechanical properties and its preparation method is an urgent need for the current industry development. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a flame-retardant and smoke-suppressing polystyrene foaming material and a preparation method thereof.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A preparation method of a flame-retardant and smoke-suppressing polystyrene foaming material, comprising the following steps:

[0008] Mix polystyrene resin, modified molybdenum trioxide, processing aids, antioxidants and foaming aids in a mixer to obtain a mixture. Then place the mixture in an extruder, heat it to 160 - 180 °C, and then add a foaming agent. After melting and mixing, foaming and extrusion, a flame-retardant and smoke-suppressing polystyrene foam material is obtained.

[0009] Furthermore, the raw materials are as follows by weight parts: 100 - 120 parts of polystyrene resin, 12 - 24 parts of modified molybdenum trioxide, 4 - 8 parts of processing aids, 5 - 7 parts of antioxidants, 1 - 3 parts of foaming aids, and 5 - 10 parts of foaming agent.

[0010] Furthermore, the processing aid is one of paraffin wax and stearic acid.

[0011] Furthermore, the antioxidant is one of antioxidant 1010, antioxidant 168, antioxidant DNP and antioxidant TNP.

[0012] Furthermore, the foaming aid is one of azodicarbonamide, potassium azodiformate and azobisisobutyronitrile.

[0013] Furthermore, the foaming agent is one of difluoroethane and tetrafluoroethane.

[0014] Adopt a composite foaming system composed of a foaming agent and a foaming aid, so that the material has a uniform and dense porous structure, endowing the material with the characteristics of low density, light weight and good heat insulation performance.

[0015] Furthermore, the modified molybdenum trioxide is prepared by the following steps:

[0016] Step 1: Add molybdenum trioxide to an ethanol aqueous solution, place it in an ultrasonic disperser, ultrasonically disperse for 15 min, then add silane coupling agent KH-550, and carry out condensation reflux at 75 °C, keep the temperature for reaction for 8 h. After the reaction is completed, filter by suction, wash the filter residue with anhydrous ethanol and deionized water for many times, and dry it under vacuum to obtain pre-modified molybdenum trioxide; the dosage ratio of ethanol aqueous solution, molybdenum trioxide and silane coupling agent KH-550 is 100 mL:1 g:5.3 g;

[0017] Use silane coupling agent KH-550 to modify molybdenum trioxide and introduce amino groups to obtain pre-modified molybdenum trioxide;

[0018] Step 2: Add pentaerythritol, triethylamine (catalyst), and tetrahydrofuran into a three-necked flask equipped with a thermometer, a stirrer, and a condenser. Under stirring at room temperature, slowly add phosphorus trichloride dropwise. After the addition is complete, raise the temperature to 60 °C and reflux for 7 h. After the reaction is completed, filter and distill off the solvent tetrahydrofuran and excess phosphorus trichloride to obtain intermediate 1. The dosage ratio of pentaerythritol, triethylamine, tetrahydrofuran, and phosphorus trichloride is 13.6 g: 25 mL: 100 mL: 28.8 g;

[0019] Pentaerythritol reacts with phosphorus trichloride with a molar ratio of pentaerythritol to phosphorus trichloride of 1:2, and the dosage of phosphorus trichloride is slightly in excess. Triethylamine removes the hydrogen chloride generated in the reaction to obtain intermediate 1. The specific reaction is as follows:

[0020]

[0021] Step 3: Add intermediate 1, triethylamine, and tetrahydrofuran into a three-necked flask equipped with a thermometer and a stirring device. After stirring evenly, add sulfathiazole and gradually raise the temperature until it reaches 77 °C. Keep the temperature for 8 h. After the reaction is completed, filter, distill under reduced pressure, purify by column chromatography, and rotary evaporate to remove the eluent to obtain intermediate 2. The dosage ratio of intermediate 1, triethylamine, tetrahydrofuran, and sulfathiazole is 28.3 g: 15 mL: 100 mL: 25.5 g;

[0022] Intermediate 1 and sulfathiazole undergo an SN nucleophilic substitution reaction. By controlling the molar ratio of the two to be close to 1:1 and the dosage of intermediate 1 to be slightly in excess, only 1 mol of sulfathiazole participates in the reaction to obtain intermediate 2. The specific reaction process is as follows:

[0023]

[0024] Step 4: Add N,N-dimethylformamide and pre-modified molybdenum trioxide into a dry round-bottomed flask and place it in an ultrasonic disperser. After ultrasonic dispersion for 15 min, add intermediate 2 and triethylamine, heat up to 70 °C, turn on magnetic stirring, stir for 6 h, then stop heating. After the temperature in the reaction flask drops to room temperature, filter, wash the filter cake with absolute ethanol 3 - 4 times, freeze-dry, and grind to obtain modified molybdenum trioxide. The dosage ratio of N,N-dimethylformamide, pre-modified molybdenum trioxide, intermediate 2, and triethylamine is 100 mL: 1 g: 13.3 g: 10 mL;

[0025] Under the catalysis of triethylamine, the chloro group on intermediate 2 and the amino group on pre-modified molybdenum trioxide undergo an amidation reaction to obtain modified molybdenum trioxide.

[0026] Molybdenum trioxide has excellent heat resistance and flame retardant properties, and the molybdenum in molybdenum trioxide is hexavalent, with its coordination number and oxidation state being easy to change. Its smoke suppression effect works in the condensed phase. As a Lewis acid coupling agent, it can promote the formation of a carbon layer through the Lewis acid mechanism, accelerate the dehalogenation of polymers, reduce the generation amount of combustible gases, and reduce the smoke amount; by modifying molybdenum trioxide, the grafted organic molecules can greatly improve the surface hydrophobicity of molybdenum trioxide, thereby improving the compatibility between molybdenum trioxide and polystyrene, promoting the dispersion of molybdenum trioxide, and enabling the performance of molybdenum trioxide to be fully exerted, greatly enhancing the heat resistance, flame retardancy, and smoke suppression performance of the matrix; in addition, the modified molybdenum trioxide molecule also contains sulfur and nitrogen elements. Compounds containing sulfur elements can generate 2 non-combustible gases such as SO

[0027] Beneficial effects of the present invention:

[0028] 1. The polystyrene foam material prepared by the present invention adopts a composite foaming system composed of a foaming agent and a foaming aid, endowing the material with the characteristics of low density, light weight, and good heat insulation performance;

[0029] 2. By modifying molybdenum trioxide, compared with ordinary molybdenum trioxide, it has better compatibility with the polystyrene matrix, the agglomeration phenomenon is alleviated, the influence on the mechanical properties of the material is reduced, and it can also greatly improve the heat resistance, flame retardancy, and smoke suppression performance of the material, and the performance is long-term stable;

[0030] Therefore, the polystyrene foam material prepared by the present invention is light in weight, has good heat insulation performance, and has stable and efficient heat resistance, flame retardancy, and smoke suppression performance, and has important application value in the technical field of foam materials. Specific embodiments

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0032] Example 1

[0033] Prepare modified molybdenum trioxide:

[0034] Step 1: Add 1 g of molybdenum trioxide into 100 mL of ethanol aqueous solution, place it in an ultrasonic disperser, ultrasonically disperse for 15 min, then add 5.3 g of silane coupling agent KH-550, and carry out condensation reflux at 75 °C, keep the temperature for reaction for 8 h. After the reaction is completed, carry out suction filtration, wash the filter residue with anhydrous ethanol and deionized water for many times, and dry it under vacuum to obtain pre-modified molybdenum trioxide;

[0035] Step 2: Add 13.6 g of pentaerythritol, 25 mL of triethylamine and 100 mL of tetrahydrofuran into a three-necked flask equipped with a thermometer, a stirrer and a condenser. Under the condition of stirring at room temperature, slowly dropwise add 28.8 g of phosphorus trichloride. After the dropping is completed, raise the temperature to 60 °C and reflux for reaction for 7 h. After the reaction is completed, filter, distill off the solvent tetrahydrofuran and excessive phosphorus trichloride to obtain intermediate 1;

[0036] Step 3: Add 28.3 g of intermediate 1, 15 mL of triethylamine and 100 mL of tetrahydrofuran into a three-necked flask equipped with a thermometer and a stirring device. After stirring evenly, add 25.5 g of sulfathiazole, and gradually raise the temperature until the temperature reaches 77 °C, keep the temperature for reaction for 8 h. After the reaction is completed, filter, carry out reduced pressure distillation, purify by column chromatography, and rotary evaporate to remove the eluent to obtain intermediate 2;

[0037] Step 4: Add 100 mL of N,N-dimethylformamide and 1 g of pre-modified molybdenum trioxide into a dry round-bottomed flask, place it in an ultrasonic disperser, ultrasonically disperse for 15 min, then add 13.3 g of intermediate 2 and 10 mL of triethylamine, heat up to 70 °C, turn on magnetic stirring, stir for reaction for 6 h, then stop heating. After the temperature in the reaction flask drops to room temperature, carry out suction filtration, wash the filter residue with anhydrous ethanol 3 times, freeze-dry, grind to obtain modified molybdenum trioxide.

[0038] Example 2

[0039] Preparation of modified molybdenum trioxide:

[0040] Step 1: Add 2 g of molybdenum trioxide into 200 mL of ethanol aqueous solution, place it in an ultrasonic disperser, ultrasonically disperse for 15 min, then add 10.6 g of silane coupling agent KH-550, and carry out condensation reflux at 75 °C, keep the temperature for reaction for 8 h. After the reaction is completed, carry out suction filtration, wash the filter residue with anhydrous ethanol and deionized water for many times, and dry it under vacuum to obtain pre-modified molybdenum trioxide;

[0041] Step 2: Add 27.2 g of pentaerythritol, 50 mL of triethylamine, and 200 mL of tetrahydrofuran into a three-necked flask equipped with a thermometer, a stirrer, and a condenser. Under stirring at room temperature, slowly add 57.6 g of phosphorus trichloride. After the addition is complete, raise the temperature to 60 °C and reflux for 7 h. After the reaction is completed, filter, and distill off the solvent tetrahydrofuran and the excess phosphorus trichloride to obtain intermediate product 1.

[0042] Step 3: Add 56.6 g of intermediate product 1, 30 mL of triethylamine, and 200 mL of tetrahydrofuran into a three-necked flask equipped with a thermometer and a stirring device. After stirring evenly, add 51.0 g of sulfathiazole, and gradually raise the temperature until it reaches 77 °C. Keep the temperature for 8 h. After the reaction is completed, filter, distill under reduced pressure, purify by column chromatography, and rotary evaporate to remove the eluent to obtain intermediate product 2.

[0043] Step 4: Add 200 mL of N,N-dimethylformamide and 2 g of pre-modified molybdenum trioxide into a dry round-bottom flask, and place it in an ultrasonic disperser. After ultrasonic dispersion for 15 min, add 26.6 g of intermediate product 2 and 20 mL of triethylamine. Heat up to 70 °C, turn on the magnetic stirrer, and stir for 6 h. Then stop heating. After the temperature in the reaction flask drops to room temperature, filter, wash the filter cake with anhydrous ethanol three times, freeze-dry, and grind to obtain modified molybdenum trioxide.

[0044] Example 3

[0045] Mix 100 g of polystyrene resin, 12 g of the modified molybdenum trioxide prepared in Example 1, 4 g of paraffin wax, 5 g of antioxidant 1010, and 1 g of azodicarbonamide in a mixer to obtain a mixture. Then place the mixture in an extruder, heat to 160 °C, and then add 5 g of difluoroethane. After melting, mixing, foaming, and extrusion, a flame-retardant and smoke-suppressing polystyrene foam material is obtained.

[0046] Example 4

[0047] Mix 110 g of polystyrene resin, 18 g of the modified molybdenum trioxide prepared in Example 2, 6 g of stearic acid, 6 g of antioxidant 168, and 2 g of azodiisobutyronitrile in a mixer to obtain a mixture. Then place the mixture in an extruder, heat to 180 °C, and then add 7.5 g of tetrafluoroethane. After melting, mixing, foaming, and extrusion, a flame-retardant and smoke-suppressing polystyrene foam material is obtained.

[0048] Example 5

[0049] Mix 120 g of polystyrene resin, 24 g of the modified molybdenum trioxide prepared in Example 2, 8 g of stearic acid, 7 g of antioxidant 168, and 3 g of azobisisobutyronitrile in a mixer to obtain a mixed material. Then, place the mixed material in an extruder, heat it to 180 °C, and then add 10 g of tetrafluoroethane. After melting and mixing, foaming and extrusion, a flame-retardant and smoke-suppressing polystyrene foam material is obtained.

[0050] Comparative Example 1

[0051] Replace the modified molybdenum trioxide in Example 5 with ordinary molybdenum trioxide of the same mass, and the remaining steps are the same as those in Example 5 to prepare a foam material.

[0052] Comparative Example 2

[0053] Replace the modified molybdenum trioxide in Example 5 with a nitrogen-based flame retardant of the same mass, and the remaining steps are the same as those in Example 5 to prepare a foam material.

[0054] Make the corresponding shapes of Examples 3, 4, and 5 and Comparative Examples 1 and 2 according to different test standards, and conduct the following performance tests:

[0055] Test the notched impact strength according to the national standard GB / T1843-2008 "Determination of Plastics - Izod Impact Strength";

[0056] Determine the notched impact strength after aging by placing the specimen in an environment of 160 °C for 48 h of hot air oxidation, and calculate the retention rate of the notched impact strength = notched impact strength after testing / notched impact strength before testing × 100%;

[0057] Determine the smoke density according to the national standard GB / T8323.2-2008 "Plastics - Smoke Generation - Part 2: Determination of Smoke Density by the Single Chamber Method"; then, after standing the specimen at room temperature for 200 days, determine the smoke density again;

[0058] Determine the limiting oxygen index of the specimen according to the national standard GB / T2406-2008 "Test Method for Flammability of Plastics", and after standing the specimen at room temperature for 200 days, determine the limiting oxygen index again;

[0059] The measured results are shown in the following table:

[0060]

[0061] As can be seen from the above table, the polystyrene foam material prepared in the examples of the present invention has higher heat resistance, flame retardancy, and smoke suppression performance than the comparative examples. Moreover, the modified molybdenum trioxide has little influence on the mechanical properties of the material. Therefore, the present invention has important application value in the technical field of foam materials.

[0062] In the description of the specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0063] The above content is only an example and explanation of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar ways to replace them. As long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a flame retardant and smoke suppressing polystyrene foam material, characterized in that: The following steps are involved: The polystyrene resin, modified molybdenum trioxide, processing aid, antioxidant and foaming aid are mixed in a mixer to obtain a mixture, and then the mixture is placed in an extruder, heated, and then a foaming agent is added. After melt mixing, foaming and extrusion, a flame retardant and smoke suppressing polystyrene foam material is obtained.

2. The method for preparing a flame retardant and smoke suppressing polystyrene foam material according to claim 1, characterized in that: The raw materials are calculated in parts by weight as follows: 100-120 parts of polystyrene resin, 12-24 parts of modified molybdenum trioxide, 4-8 parts of processing aid, 5-7 parts of antioxidant, 1-3 parts of foaming aid, and 5-10 parts of foaming agent.

3. The method for preparing a flame retardant and smoke suppressing polystyrene foam material according to claim 1, characterized in that: The foaming aid is one of azodicarbonamide, azodicarbonamide potassium formate and azobisisobutyronitrile.

4. The method for preparing a flame retardant and smoke suppressing polystyrene foam material according to claim 1, characterized in that: The foaming agent is one of difluoroethane and tetrafluoroethane.

5. The method for preparing a flame retardant and smoke suppressing polystyrene foam material according to claim 1, characterized in that: The modified molybdenum trioxide is prepared by the following steps: Step 1, add molybdenum trioxide to an ethanol aqueous solution, ultrasonically disperse, then add a silane coupling agent KH-550, condense and reflux at 75° C., keep warm for 8 hours, and after the reaction is completed, filter, wash, and dry to obtain pre-modified molybdenum trioxide; Step 2, pentaerythritol, triethylamine and tetrahydrofuran are added into a three-necked flask, and phosphorus trichloride is slowly added dropwise under stirring at room temperature. After the addition is complete, the temperature is raised to 60° C., and the reaction is refluxed for 7 hours. After the reaction is completed, the reaction is filtered and distilled to obtain an intermediate product 1; Step 3, add the intermediate product 1, triethylamine and tetrahydrofuran into a three-necked flask, stir evenly, then add sulfathiazole, and gradually increase the temperature until the temperature reaches 77°C, keep the temperature for 8 hours, and after the reaction is completed, filter, distill under reduced pressure, purify by column chromatography, and rotary evaporate to obtain the intermediate product 2; Step 4: Add N,N-dimethylformamide and pre-modified molybdenum trioxide to a flask, add intermediate product 2 and triethylamine after ultrasonic dispersion, heat to 70°C, turn on magnetic stirring, stir the reaction for 6 hours and then stop heating. After the temperature in the reaction bottle drops to room temperature, filter, wash the residue, freeze-dry and grind to obtain modified molybdenum trioxide.

6. The method for preparing a flame retardant and smoke suppressing polystyrene foam material according to claim 5, characterized in that: In step 1, the ratio of the amount of ethanol aqueous solution, molybdenum trioxide, and silane coupling agent KH-550 is 100mL:1g:5.3g.

7. The method for preparing a flame retardant and smoke suppressing polystyrene foam material according to claim 5, characterized in that: In step 2, the ratio of pentaerythritol, triethylamine, tetrahydrofuran and phosphorus trichloride is 13.6 g: 25 mL: 100 mL: 28.8 g.

8. The method for preparing a flame retardant and smoke suppressing polystyrene foam material according to claim 5, characterized in that: In step 3, the ratio of the intermediate product 1, triethylamine, tetrahydrofuran and sulfathiazole is 28.3 g:15 mL:100 mL:25.5 g.

9. The method for preparing a flame retardant and smoke suppressing polystyrene foam material according to claim 5, characterized in that: In step 4, the ratio of the amount of N,N-dimethylformamide, pre-modified molybdenum trioxide, intermediate product 2, and triethylamine is 100mL:1g:13.3g:10mL.

10. A flame retardant and smoke suppressing polystyrene foam material, characterized in that: Prepared according to the method according to any one of claims 1 to 9.

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