Reactive nitrogen and phosphorus-containing graphene flame retardant modified polystyrene foam and preparation method thereof

Abstract

The invention relates to the technical field of foam materials, and discloses a reaction type nitrogen and phosphorus-containing graphene flame retardant modified polystyrene foam, a polystyrene grafted nitrogen and phosphorus-containing graphene flame retardant has a polystyrene molecular chain, so that the polystyrene grafted nitrogen and phosphorus-containing graphene flame retardant has good interfacial compatibility with expandable polystyrene, and the expandable polystyrene has good mechanical properties. The nitrogen-phosphorus-containing graphene flame retardant has good dispersibility in expandable polystyrene, reduces the graphene agglomeration phenomenon, reduces the influence of the nitrogen-phosphorus-containing graphene flame retardant on the mechanical strength of the polystyrene foam board, and enables the modified polystyrene foam to maintain good tensile strength, bending strength and other mechanical strength. Meanwhile, the nitrogen-phosphorus-containing graphene flame retardant forms a nitrogen-phosphorus synergistic flame-retardant system in the combustion process, and graphene is uniformly dispersed in polystyrene foam to form a continuous carbon layer, so that the polystyrene foam is endowed with carbon forming property and smoke suppression property under the synergistic effect, and the flame retardance and smoke suppression property of the foam material are enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of foam materials, in particular to a reactive nitrogen-phosphorus-containing graphene flame retardant modified polystyrene foam and a preparation method thereof. Background Art

[0002] Foam plastics contain a large amount of gas microporous structure and have the characteristics of light texture, good thermal insulation and high thermal insulation, such as phenolic foam, polystyrene foam, polyvinyl chloride foam, etc. Among them, polystyrene foam board is more widely used, and has important applications in composite board insulation, floor heating, furniture decoration, etc. However, polystyrene foam is easy to burn and then releases a lot of toxic smoke, which limits the development of polystyrene foam.

[0003] Adding flame retardants to polystyrene foam is an effective method to improve its flame retardancy. Flame retardants can be divided into additive flame retardants and reactive flame retardants. Relatively speaking, reactive flame retardants can be used as a reactive monomer to participate in the polymerization reaction of polymers, so that the polymer material itself contains flame retardant components. In addition, the interface compatibility between reactive flame retardants and polymer materials is better, and the mechanical strength and performance of the materials will not be affected. Therefore, the development of reactive flame retardants and their application in polystyrene foam materials has important industrial development significance. CN103275408B "A method for preparing a graphene / layered double hydroxide composite flame retardant and a polystyrene nano flame retardant composite material" discloses that graphene and layered double hydroxide constitute a composite flame retardant to improve the flame retardant properties of polystyrene. In recent years, graphene has broad application prospects in the field of flame retardancy. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a reactive nitrogen-phosphorus-containing graphene flame retardant modified polystyrene foam and a preparation method, which solves the problems of poor flame retardancy of polystyrene foam boards and low interface compatibility between graphene flame retardants and polystyrene.

[0005] To achieve the above object, the present invention provides the following technical solution: a reactive nitrogen-phosphorus graphene flame retardant-modified polystyrene foam, wherein the preparation method of the reactive nitrogen-phosphorus graphene flame retardant-modified polystyrene foam is as follows: (1) Add distilled water and graphene oxide into a reaction bottle, add mercaptopropyltrimethoxysilane after uniform dispersion, heat to 90-110 °C, reflux for 5-10 h, centrifuge, wash with ethanol and distilled water, and dry to obtain mercapto-modified graphene.

[0006] (2) Add solvent and co-solvent to the reaction bottle, add thiol-modified graphene, and after evenly dispersing, add bisacryloxyphosphoramide compound with the molecular formula C 26 H 32 N2O10 P2, and photoinitiator dimethyl benzoate (DMPA), undergo click reaction, distill under reduced pressure, wash with tetrahydrofuran and acetone, and dry to obtain terminal acryloxyphosphoramide-modified graphene.

[0007] (3) Add distilled water and end-acryloxyphosphoramide-modified graphene into a reaction bottle, and after uniform dispersion, add styrene, emulsifier sodium dodecyl sulfate (SDS) and OP-10, stir the solution and dropwise add initiator potassium persulfate (KPS) to cause polymerization reaction, centrifuge, wash with ethanol and deionized water, and dry to obtain polystyrene grafted nitrogen-phosphorus graphene flame retardant.

[0008] (4) Expandable polystyrene and polystyrene grafted nitrogen-phosphorus graphene flame retardant are placed in an extruder, melt-mixed and then extruded, the materials are pre-foamed and aged, and then the materials are placed in a foaming molding machine, heated by water vapor and molded to obtain reactive nitrogen-phosphorus graphene flame retardant modified polystyrene foam.

[0009] Preferably, in step (1), the mass fractions of distilled water are 25000-40000 parts, the mass fractions of graphene oxide are 100 parts, and the mass fractions of mercaptopropyltrimethoxysilane are 220-450 parts.

[0010] Preferably, in step (2), the mass fractions of solvent are 12000-25000 parts, the mass fractions of co-solvent are 4000-10000 parts, the mass fractions of mercapto-modified graphene are 100 parts, the mass fractions of bisacryloxyphosphoramide compound are 400-850 parts, and the mass fractions of benzoin dimethyl ether are 8-15 parts.

[0011] Preferably, in step (2), the solvent is toluene, and the co-solvent is tetrahydrofuran or acetone.

[0012] Preferably, the click reaction in step (2) is carried out under ultraviolet light for 4-12 h.

[0013] Preferably, in step (3), the mass fractions of distilled water are 300-1000 parts, the terminal acryloxyphosphoramide modified graphene is 100 parts, the mass fractions of styrene are 120-300 parts, the mass fractions of sodium dodecyl sulfate are 2-6 parts, the mass fractions of OP-10 are 4-15 parts, and the mass fractions of potassium persulfate are 0.6-1.5 parts.

[0014] Preferably, the polymerization reaction in step (3) is carried out at 70-80° C. for 5-10 h.

[0015] Preferably, in step (3), the mass fraction of expandable polystyrene is 100 parts, and the mass fraction of polystyrene grafted nitrogen-phosphorus-containing graphene flame retardant is 0.5-5 parts.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The invention discloses a reactive nitrogen-phosphorus graphene flame retardant modified polystyrene foam. The surface of the thiol-modified graphene contains active thiol functional groups. The bisacryloxy phosphoramide compound contains two terminal olefin groups. Under the irradiation of ultraviolet light, benzoin dimethyl ether light-initiates the thiol of the graphene and one terminal olefin group to cause a thiol-olefin click reaction, so that the acryloxy phosphoramide compound is chemically modified into the graphene to obtain the terminal acryloxy phosphoramide modified graphene.

[0017] The invention discloses a reactive nitrogen-phosphorus graphene flame retardant modified polystyrene foam. The terminal acryloxy phosphoramide modified on the surface of graphene contains phosphoramide and piperazine functional groups, constituting a nitrogen-phosphorus synergistic flame retardant component, and forms a nitrogen-phosphorus graphene flame retardant with graphene. The terminal acryloxy phosphoramide has a polymerizable alkenyl functional group and can be used as a reactive flame retardant. Under the initiation of potassium persulfate, the terminal acryloxy phosphoramide undergoes a polymerization reaction with a styrene monomer to obtain a polystyrene-grafted nitrogen-phosphorus graphene flame retardant, thereby chemically grafting the surface of the nitrogen-phosphorus graphene flame retardant to introduce a polystyrene molecular chain.

[0018] The reactive nitrogen-phosphorus graphene flame retardant modified polystyrene foam has good interface compatibility with expandable polystyrene due to the polystyrene molecular chain. The nitrogen-phosphorus graphene flame retardant has good dispersibility in expandable polystyrene, reduces graphene agglomeration, reduces the influence of the nitrogen-phosphorus graphene flame retardant on the mechanical strength of the polystyrene foam board, and maintains good tensile and bending mechanical strengths of the modified polystyrene foam. Meanwhile, the nitrogen-phosphorus graphene flame retardant forms a nitrogen-phosphorus synergistic flame retardant system during combustion, and graphene is evenly dispersed in the polystyrene foam to form a continuous carbon layer, which gives the polystyrene foam carbonization and smoke suppression properties under the synergistic effect, and enhances the flame retardancy and smoke suppression of the foam material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the reaction formula of mercapto-modified graphene and bisacryloxyphosphoramide compound; Figure 2 It is the reaction formula of terminal acryloxyphosphoramide modified graphene and styrene. DETAILED DESCRIPTION

[0020] To achieve the above object, the present invention provides the following implementation modes and examples: A method for preparing a reactive nitrogen-phosphorus-containing graphene flame retardant-modified polystyrene foam is as follows: (1) Add 25000-40000 parts by weight of distilled water and 100 parts by weight of graphene oxide into a reaction bottle, and after uniform dispersion, add 220-450 parts by weight of mercaptopropyltrimethoxysilane, heat to 90-110°C, reflux for 5-10 h, centrifuge, wash with ethanol and distilled water, and dry to obtain mercapto-modified graphene.

[0021] (2) Add 12000-25000 parts by weight of toluene solvent, 4000-10000 parts by weight of tetrahydrofuran or acetone as a co-solvent to the reaction bottle, add 100 parts of mercapto-modified graphene, disperse evenly, and then add 400-850 parts of bisacryloxyphosphoramide compound (C 26 H 32 N2O 10 P2), and 8-15 parts of photoinitiator dimethyl benzoate (DMPA), irradiated under ultraviolet light, a click reaction occurred for 4-12 hours, distilled under reduced pressure, washed with tetrahydrofuran and acetone, and dried to obtain terminal acryloxyphosphoramide modified graphene.

[0022] (3) Add 300-1000 parts by weight of distilled water and 100 parts by weight of terminal acryloxyphosphoramide-modified graphene into a reaction bottle, and after uniform dispersion, add 120-300 parts of styrene, 2-6 parts of emulsifier sodium dodecyl sulfate and 4-15 parts of OP-10, stir the solution and dropwise add 0.6-1.5 parts of initiator potassium persulfate, and carry out polymerization reaction at 70-80°C for 5-10 hours. Centrifuge, wash with ethanol and deionized water, and dry to obtain a polystyrene grafted nitrogen-phosphorus graphene flame retardant.

[0023] (4) 100 parts by weight of expandable polystyrene and 0.5-5 parts by weight of polystyrene grafted nitrogen-phosphorus graphene flame retardant are placed in an extruder, melt-mixed and then extruded, the material is pre-foamed and aged, and then the material is placed in a foaming molding machine, heated by water vapor and molded to obtain a reactive nitrogen-phosphorus graphene flame retardant modified polystyrene foam. Example 1

[0024] (1) Add 250 g of distilled water and 1 g of graphene oxide into a reaction bottle, disperse them evenly, add 2.5 g of mercaptopropyltrimethoxysilane, heat to 90 °C, reflux for 5 h, centrifuge, wash with ethanol and distilled water, and dry to obtain mercapto-modified graphene.

[0025] (2) Add 120 g of toluene solvent, 40 g of tetrahydrofuran or acetone as a co-solvent to the reaction bottle, add 1 g of thiol-modified graphene, and after evenly dispersing, add 4 g of bisacryloxyphosphoramide compound (C 26 H 32 N2O 10P2), and 0.08 g of photoinitiator benzoin dimethyl ether, irradiated under ultraviolet light, a click reaction occurred for 4 h, distilled under reduced pressure, washed with tetrahydrofuran and acetone, and dried to obtain terminal acryloxyphosphoramide-modified graphene.

[0026] (3) Add 30 g of distilled water and 10 g of terminal acryloxyphosphoramide-modified graphene into a reaction bottle. After uniform dispersion, add 12 g of styrene, 0.2 g of emulsifier sodium dodecyl sulfate and 0.4 g of OP-10. Stir the solution and dropwise add 0.06 g of initiator potassium persulfate. Incubate the mixture at 70 °C for 5 h to allow polymerization to occur. The mixture is centrifuged, washed with ethanol and deionized water, and dried to obtain a polystyrene grafted nitrogen-phosphorus graphene flame retardant.

[0027] (4) 50 g of expandable polystyrene and 0.25 g of polystyrene grafted nitrogen-phosphorus graphene flame retardant are placed in an extruder, melt-mixed and then extruded, the material is pre-foamed and aged, and then the material is placed in a foaming molding machine, heated by water vapor and molded to obtain a reactive nitrogen-phosphorus graphene flame retardant modified polystyrene foam. Example 2

[0028] (1) Add 300 g of distilled water and 1 g of graphene oxide into a reaction bottle, disperse them evenly, add 3.2 g of mercaptopropyltrimethoxysilane, heat to 110 °C, reflux for 5 h, centrifuge, wash with ethanol and distilled water, and dry to obtain mercapto-modified graphene.

[0029] (2) Add 160 g of toluene solvent, 60 g of tetrahydrofuran or acetone as a co-solvent to the reaction bottle, add 1 g of thiol-modified graphene, and after evenly dispersing, add 5.5 g of bisacryloxyphosphoramide compound (C 26 H 32 N2O 10 P2), and 0.1 g of photoinitiator benzoin dimethyl ether, were irradiated under ultraviolet light to produce a click reaction for 6 h, and then distilled under reduced pressure, washed with tetrahydrofuran and acetone, and dried to obtain terminal acryloxyphosphoramide-modified graphene.

[0030] (3) Add 50 g of distilled water and 10 g of terminal acryloxyphosphoramide-modified graphene into a reaction bottle. After uniform dispersion, add 18 g of styrene, 0.3 g of emulsifier sodium dodecyl sulfate and 0.8 g of OP-10. Stir the solution and dropwise add 0.09 g of initiator potassium persulfate. Incubate the mixture at 80 °C for 5 h to allow polymerization to occur. The mixture is centrifuged, washed with ethanol and deionized water, and dried to obtain a polystyrene grafted nitrogen-phosphorus graphene flame retardant.

[0031] (4) 50 g of expandable polystyrene and 0.8 g of polystyrene grafted nitrogen-phosphorus graphene flame retardant are placed in an extruder, melt-mixed and then extruded, the material is pre-foamed and aged, and then the material is placed in a foaming molding machine, heated by water vapor and molded to obtain a reactive nitrogen-phosphorus graphene flame retardant modified polystyrene foam. Example 3

[0032] (1) Add 350 g of distilled water and 1 g of graphene oxide into a reaction bottle. After uniform dispersion, add 3.8 g of mercaptopropyltrimethoxysilane. Heat to 100 °C and reflux for 8 h. Centrifuge, wash with ethanol and distilled water, and dry to obtain mercapto-modified graphene.

[0033] (2) Add 200 g of toluene solvent, 80 g of tetrahydrofuran or acetone as a co-solvent to the reaction bottle, add 1 g of thiol-modified graphene, and after evenly dispersing, add 7 g of bisacryloxyphosphoramide compound (C 26 H 32 N2O 10 P2), and 0.12 g of photoinitiator benzoin dimethyl ether, irradiated under ultraviolet light, click reaction occurred for 10 h, distilled under reduced pressure, washed with tetrahydrofuran and acetone, and dried to obtain terminal acryloxyphosphoramide modified graphene.

[0034] (3) Add 80 g of distilled water and 10 g of terminal acryloxyphosphoramide-modified graphene into a reaction bottle. After uniform dispersion, add 25 g of styrene, 0.45 g of emulsifier sodium dodecyl sulfate and 1.2 g of OP-10. Stir the solution and dropwise add 0.12 g of initiator potassium persulfate. Incubate the mixture at 75 °C for 8 h to allow polymerization to occur. The mixture is centrifuged, washed with ethanol and deionized water, and dried to obtain a polystyrene grafted nitrogen-phosphorus graphene flame retardant.

[0035] (4) 50 g of expandable polystyrene and 2 g of polystyrene grafted nitrogen-phosphorus graphene flame retardant are placed in an extruder, melt-mixed and then extruded, the material is pre-foamed and aged, and then the material is placed in a foaming molding machine, heated by water vapor and molded to obtain a reactive nitrogen-phosphorus graphene flame retardant modified polystyrene foam. Example 4

[0036] (1) Add 400 g of distilled water and 1 g of graphene oxide into a reaction bottle, disperse them evenly, add 4.5 g of mercaptopropyltrimethoxysilane, heat to 110 °C, reflux for 10 h, centrifuge, wash with ethanol and distilled water, and dry to obtain mercapto-modified graphene.

[0037] (2) Add 250 g of toluene solvent, 100 g of tetrahydrofuran or acetone as a co-solvent to the reaction bottle, add 1 g of thiol-modified graphene, and after evenly dispersing, add 8.5 g of bisacryloxyphosphoramide compound (C 26 H 32 N2O 10 P2), and 0.15g of photoinitiator benzoin dimethyl ether, irradiated under ultraviolet light, click reaction occurred for 12 h, distilled under reduced pressure, washed with tetrahydrofuran and acetone, and dried to obtain terminal acryloxyphosphoramide modified graphene.

[0038] (3) Add 100 g of distilled water and 10 g of terminal acryloxyphosphoramide-modified graphene into a reaction bottle. After uniform dispersion, add 30 g of styrene, 0.6 g of emulsifier sodium dodecyl sulfate and 1.5 g of OP-10. Stir the solution and dropwise add 0.15 g of initiator potassium persulfate. Incubate the mixture at 80 °C for 10 h for polymerization. Centrifuge, wash with ethanol and deionized water, and dry to obtain a polystyrene grafted nitrogen-phosphorus graphene flame retardant.

[0039] (4) 50 g of expandable polystyrene and 2.5 g of polystyrene grafted nitrogen-phosphorus graphene flame retardant are placed in an extruder, melt-mixed and then extruded, the material is pre-foamed and aged, and then the material is placed in a foaming molding machine, heated by water vapor and molded to obtain a reactive nitrogen-phosphorus graphene flame retardant modified polystyrene foam.

[0040] Comparative Example 1 (1) Add 300 g of distilled water and 1 g of graphene oxide into a reaction bottle, disperse them evenly, add 4 g of mercaptopropyltrimethoxysilane, heat to 100 °C, reflux for 5 h, centrifuge, wash with ethanol and distilled water, and dry to obtain mercapto-modified graphene.

[0041] (2) 50 g of expandable polystyrene and 1 g of mercapto-modified graphene are placed in an extruder, melt-mixed and then extruded, the material is pre-foamed and aged, and then the material is placed in a foaming molding machine, heated by water vapor and molded to obtain graphene-modified polystyrene foam.

[0042] Comparative Example 2 (1) Add 350 g of distilled water and 1 g of graphene oxide into a reaction bottle, disperse them evenly, add 3.5 g of mercaptopropyltrimethoxysilane, heat to 100 °C, reflux for 5 h, centrifuge, wash with ethanol and distilled water, and dry to obtain mercapto-modified graphene.

[0043] (2) Add 220 g of toluene solvent, 80 g of tetrahydrofuran or acetone as a co-solvent to the reaction bottle, add 1 g of thiol-modified graphene, and after evenly dispersing, add 6.5 g of bisacryloxyphosphoramide compound (C 26 H 32 N2O 10 P2), and 0.1 g of photoinitiator benzoin dimethyl ether, irradiated under ultraviolet light, click reaction occurred for 12 h, distilled under reduced pressure, washed with tetrahydrofuran and acetone, and dried to obtain terminal acryloxyphosphoramide-modified graphene.

[0044] (3) 50 g of expandable polystyrene and 2 g of terminal acryloxyphosphoramide-modified graphene are placed in an extruder, melt-mixed and then extruded, the material is pre-foamed and aged, and then the material is placed in a foaming molding machine, heated by water vapor and molded to obtain nitrogen-phosphorus graphene flame retardant-modified polystyrene foam.

[0045] The modified polystyrene foams prepared in the examples and comparative examples were cut into standard specimens with a specification of 100 mm×10 mm×10 mm, and the flame retardancy of the specimens was tested by a CZF-5 horizontal vertical combustion instrument according to the standard of fire protection grade UL-94.

[0046]

[0047] According to GB / T 1040.1-2018, the tensile strength of polystyrene standard specimens was tested using a WDW tensile testing machine.

[0048]

[0049] According to the standard of GB / T 9341-2008, the bending strength of polystyrene standard specimens was tested using a CTM electronic universal testing machine.

[0050]

Claims

1. A reactive nitrogen-phosphorus-containing graphene flame retardant modified polystyrene foam, characterized in that: The preparation method of the reactive nitrogen-phosphorus-containing graphene flame retardant modified polystyrene foam is as follows: (1) Adding distilled water and graphene oxide to a reaction bottle, adding mercaptopropyltrimethoxysilane after uniform dispersion, heating to 90-110°C, reflux reaction for 5-10 h, centrifugation, washing with ethanol and distilled water, and drying to obtain mercapto-modified graphene; (2) Add solvent and co-solvent to the reaction bottle, add thiol-modified graphene, and after evenly dispersing, add bisacryloxyphosphoramide compound with the molecular formula C 26 H 32 N2O 10 P2, and photoinitiator benzoin dimethyl ether, undergo click reaction, distill under reduced pressure, wash with tetrahydrofuran and acetone, and dry to obtain terminal acryloxyphosphoramide-modified graphene; (3) adding distilled water and terminal acryloxyphosphoramide modified graphene to a reaction bottle, adding styrene, emulsifier sodium dodecyl sulfate and OP-10 after uniform dispersion, stirring the solution and adding initiator potassium persulfate dropwise to cause polymerization reaction, centrifuging, washing with ethanol and deionized water, and drying to obtain polystyrene grafted nitrogen-phosphorus graphene flame retardant; (4) Expandable polystyrene and polystyrene grafted nitrogen-phosphorus graphene flame retardant are placed in an extruder, melt-mixed and then extruded, the materials are pre-foamed and aged, and then the materials are placed in a foaming molding machine, heated by water vapor and molded to obtain reactive nitrogen-phosphorus graphene flame retardant modified polystyrene foam.

2. The reactive nitrogen-phosphorus-containing graphene flame retardant modified polystyrene foam according to claim 1, characterized in that: In the step (1), the mass fractions of distilled water are 25000-40000 parts, the mass fractions of graphene oxide are 100 parts, and the mass fractions of mercaptopropyltrimethoxysilane are 220-450 parts.

3. The reactive nitrogen-phosphorus-containing graphene flame retardant modified polystyrene foam according to claim 1, characterized in that: In the step (2), the mass fractions of the solvent are 12000-25000 parts, the mass fractions of the cosolvent are 4000-10000 parts, the mass fractions of the mercapto-modified graphene are 100 parts, the mass fractions of the bisacryloxyphosphoramide compound are 400-850 parts, and the mass fractions of benzoin dimethyl ether are 8-15 parts.

4. The reactive nitrogen-phosphorus-containing graphene flame retardant modified polystyrene foam according to claim 1, characterized in that: In the step (2), the solvent is toluene, and the co-solvent is tetrahydrofuran or acetone.

5. The reactive nitrogen-phosphorus-containing graphene flame retardant modified polystyrene foam according to claim 1, characterized in that: The click reaction in step (2) is carried out under ultraviolet light for 4-12 hours.

6. The reactive nitrogen-phosphorus-containing graphene flame retardant modified polystyrene foam according to claim 1, characterized in that: In the step (3), the mass fractions of distilled water are 300-1000 parts, the end-acryloxyphosphoramide-modified graphene is 100 parts, styrene is 120-300 parts, sodium dodecyl sulfate is 2-6 parts, OP-10 is 4-15 parts, and potassium persulfate is 0.6-1.5 parts.

7. The reactive nitrogen-phosphorus-containing graphene flame retardant modified polystyrene foam according to claim 1, characterized in that: In the step (3), the polymerization reaction is carried out at 70-80°C for 5-10 hours.

8. The reactive nitrogen-phosphorus-containing graphene flame retardant modified polystyrene foam according to claim 1, characterized in that: In the step (3), the mass fraction of expandable polystyrene is 100 parts, and the mass fraction of polystyrene grafted nitrogen-phosphorus-containing graphene flame retardant is 0.5-5 parts.

Images