Functionalized nano-silica flame-retardant modified polyethylene packaging bag and preparation method thereof

Abstract

The invention relates to the technical field of polyethylene, and discloses a functionalized nano-silica flame-retardant modified polyethylene packaging bag, which is characterized in that functionalized nano-silica modified by phosphoric acid amide-piperazine is used as a composite flame retardant modifier, polyethylene is subjected to blending modification, and through blending, extrusion and film blowing treatment, the flame-retardant modified polyethylene packaging bag is obtained. Phosphoric acid amide and piperazine functional groups introduced to the surface of the nano silicon dioxide form a nitrogen-phosphorus synergistic flame-retardant system, under high-temperature combustion, thermal decomposition is carried out to generate a phosphoric acid derivative with strong water absorption, piperazine is used as a nitrogen source and an expansion carbon source, and the nitrogen-phosphorus synergistic flame-retardant system is used as a flame-retardant agent to prepare the functional nano silicon dioxide flame-retardant modified polyethylene packaging bag. A continuous carbon barrier layer is formed on the surface of silicon dioxide, and nano silicon dioxide is uniformly dispersed in the carbon barrier layer to form a physical cross-linked network, so that the effect of consolidating a carbon layer is achieved, the formation of a compact and stable linked carbon barrier layer is promoted, and the effects of blocking oxygen, inhibiting smoke escape and preventing polyethylene molten drops are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of polyethylene, in particular to a functionalized nano-silicon dioxide flame-retardant modified polyethylene packaging bag and a preparation method thereof. Background Art

[0002] Polyethylene has the advantages of being odorless, non-toxic, highly resistant to acid and alkali, low in water absorption, and excellent in electrical insulation. This makes polyethylene a packaging material that is widely used in food packaging, medical drug packaging, etc. However, due to the poor flame retardant properties of polyethylene packaging bags, it is easy to burn, drip, and emit toxic smoke, which limits the practical application of polyethylene packaging bags. In recent years, flame retardant modification of polyethylene materials has been a hot research topic.

[0003] Traditional flame retardants mainly include silicon-based flame retardants, nitrogen-phosphorus flame retardants, halogen-containing flame retardants, etc. Among them, nitrogen-phosphorus flame retardant is a halogen-free, low-pollution, high-efficiency flame retardant with the effects of charring, anti-drip and smoke suppression. Nano-silica is a common inorganic nano-filler, widely used in polymer materials such as polyethylene and polyurethane. Through the mechanical strength and thermal stability of the material, and the fact that nano-silica contains active silanol groups and has good chemical modifiability, the nitrogen-phosphorus flame retardant can be chemically modified to the surface of nano-silica to obtain flame-retardant functional nano-fillers to modify polyethylene packaging bag materials.

[0004] 1. Technical issues to be resolved In view of the shortcomings of the prior art, the present invention provides a functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag and a preparation method, which solves the problems of flammability and dripping of traditional polyethylene packaging materials.

[0005] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag, wherein the preparation method of the functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag comprises the following steps: (1) Add ethanol and nano-silica to deionized water, add N-[3-(trimethoxysilyl)propyl]ethylenediamine after ultrasonic dispersion, react at 60-80 °C for 2-4 h, centrifuge and wash with ethanol to obtain amino silica.

[0006] (2) Add amino-modified nano-silica and phenylphosphoryl dichloride to tetrahydrofuran solvent, stir to dissolve, then dropwise add catalyst triethylamine, react, centrifuge, and wash with ethanol and acetone to obtain phosphoryl chloride silica.

[0007] (3) Add phosphoryl chloride silica and piperazine to chloroform solvent, stir to dissolve, then dropwise add catalyst triethylamine to react, add diphenylphosphine chloride after the reaction is completed, react, centrifuge, wash with dichloromethane and ethanol, and obtain phosphoryl chloride-piperazine modified functionalized nano-silica.

[0008] (4) Low-density polyethylene, functionalized nano-silica, antioxidant 1010, and lubricant calcium stearate are placed in a twin-screw extruder, melt-blended, and extruded into granules. The masterbatch is then placed in a film blowing machine for film blowing to produce a functionalized nano-silica flame-retardant modified polyethylene packaging bag.

[0009] Preferably, the mass ratio of nano-silica to N-[3-(trimethoxysilyl)propyl]ethylenediamine in step (1) is 100:3-8.

[0010] Preferably, the mass ratio of the amino-modified nano-silica, phenylphosphoryl dichloride and triethylamine in step (2) is 100:15-40:12-35.

[0011] Preferably, the reaction in step (2) is carried out at 0-10°C for 6-12 hours.

[0012] Preferably, the mass ratio of silicon dioxide phosphoryl chloride, piperazine and triethylamine in step (3) is 100:8-30:22-85.

[0013] Preferably, the reaction in step (3) is carried out at 15-30° C. for 12-24 h.

[0014] Preferably, the reaction in step (3) is carried out at 15-30° C. for 12-36 h.

[0015] Preferably, the mass ratio of low-density polyethylene, functionalized nano-silica, antioxidant 1010, and calcium stearate in step (4) is 100:0.5-3:0.2-0.6:0.25-0.8.

[0016] Preferably, the melt blending temperature in step (4) is 160-170°C, and the extrusion temperature is 170-175°C.

[0017] 3. Beneficial technical effects Compared with the prior art, the present invention has the following beneficial technical effects: The functionalized nano-silica flame-retardant modified polyethylene packaging bag is modified by N-[3-(trimethoxysilyl)propyl]ethylenediamine to introduce amino and imino groups on the surface of nano-silica, and then, under the catalytic action of triethylamine, a phosphoryl chloride group of phenyl phosphoryl dichloride is reacted with the amino and imino groups to obtain phosphoryl chloride silicon dioxide, thereby introducing phosphoryl chloride functional groups on the surface of nano-silica, and then the phosphoryl chloride functional groups undergo phosphoramidation reaction with an imino group of piperazine to introduce piperazine functional groups, and unreacted imino groups undergo phosphoramidation reaction with the phosphoryl chloride functional groups of diphenylphosphinyl chloride to further introduce diphenylphosphine oxide functional groups to obtain phosphoramidite-piperazine modified functionalized nano-silica.

[0018] The functionalized nano-silica flame-retardant modified polyethylene packaging bag uses phosphoric acid amide-piperazine modified functionalized nano-silica as a composite flame retardant modifier to modify polyethylene, and obtains the functionalized nano-silica flame-retardant modified polyethylene packaging bag through blending, extrusion and film blowing. Phosphoric acid amide and piperazine functional groups introduced on the surface of the nano-silica form a nitrogen-phosphorus synergistic flame retardant system, which thermally decomposes under high-temperature combustion to produce highly water-absorbing phosphoric acid derivatives, while piperazine, as a nitrogen source and an expanding carbon source, forms a continuous carbon barrier layer on the surface of the nano-silica, and the nano-silica is uniformly dispersed in the carbon barrier layer to form a physical cross-linking network, which plays a role in consolidating the carbon layer and promoting the formation of a dense and stable connected carbon barrier layer, thereby playing an excellent role in blocking oxygen, inhibiting smoke escape, and preventing polyethylene molten droplets, and significantly enhancing the flame retardant performance of the polyethylene packaging bag. DETAILED DESCRIPTION

[0019] To achieve the above object, the present invention provides the following specific implementation methods and examples: A method for preparing a functionalized nano-silicon dioxide flame-retardant modified polyethylene packaging bag comprises the following steps: (1) Add ethanol and nano-silica to deionized water, add N-[3-(trimethoxysilyl)propyl]ethylenediamine after ultrasonic dispersion, the mass ratio of the two is 100:3-8, react at 60-80 °C for 2-4 h, centrifuge and wash with ethanol to obtain amino silica.

[0020] (2) Add amino nano-silica and phenylphosphoryl dichloride to tetrahydrofuran solvent, stir to dissolve, then add catalyst triethylamine dropwise, the mass ratio of the three is 100:15-40:12-35, react at 0-10 ℃ for 6-12 h, centrifuge, wash with ethanol and acetone, and obtain phosphoryl chloride silica.

[0021] (3) Add phosphoryl chloride silica and piperazine to chloroform solvent, stir to dissolve, then add catalyst triethylamine dropwise, react at 15-30 ℃ for 12-24 h, add diphenylphosphine chloride after the reaction is completed, the mass ratio of phosphoryl chloride silica, piperazine and triethylamine is 100:8-30:22-85, react at 15-30 ℃ for 12-36 h, centrifuge, wash with dichloromethane and ethanol, and obtain phosphoryl chloride-piperazine modified functionalized nano-silica.

[0022] (4) Low-density polyethylene, functionalized nano-silica, antioxidant 1010, and lubricant calcium stearate in a mass ratio of 100:0.5-3:0.2-0.6:0.25-0.8 are placed in a twin-screw extruder, melt-blended at 160-170°C, extruded and granulated at 170-175°C, and then the masterbatch is placed in a film blowing machine for film blowing to produce a functionalized nano-silica flame-retardant modified polyethylene packaging bag.

[0023] Example 1

[0024] (1) Add ethanol and nano-silica to deionized water, add N-[3-(trimethoxysilyl)propyl]ethylenediamine after ultrasonic dispersion, the mass ratio of the two is 100:3, react at 60 °C for 2 h, centrifuge and wash with ethanol to obtain amino silica.

[0025] (2) Add amino-modified nano-silica and phenylphosphoryl dichloride to tetrahydrofuran solvent, stir to dissolve, then add catalyst triethylamine dropwise in a mass ratio of 100:15:12, react at 0°C for 6 h, centrifuge, and wash with ethanol and acetone to obtain phosphoryl chloride silica.

[0026] (3) Add phosphoryl chloride silica and piperazine to chloroform solvent, stir to dissolve, then add catalyst triethylamine dropwise, react at 15 °C for 12 h, add diphenylphosphine chloride after the reaction is completed, the mass ratio of phosphoryl chloride silica, piperazine and triethylamine is 100:8:22, react at 15 °C for 12 h, centrifuge, wash with dichloromethane and ethanol, and obtain phosphoryl chloride-piperazine modified functionalized nano-silica.

[0027] (4) Low-density polyethylene, functionalized nano-silica, antioxidant 1010, and lubricant calcium stearate in a mass ratio of 100:0.5:0.2:0.25 were placed in a twin-screw extruder, melt-blended at 160°C, extruded into granules at 170°C, and then the masterbatch was placed in a film blowing machine for film blowing to produce functionalized nano-silica flame-retardant modified polyethylene packaging bags.

[0028] Example 2

[0029] (1) Add ethanol and nano-silica to deionized water, add N-[3-(trimethoxysilyl)propyl]ethylenediamine after ultrasonic dispersion, the mass ratio of the two is 100:4, react at 60 °C for 3 h, centrifuge and wash with ethanol to obtain amino silica.

[0030] (2) Add amino-modified nano-silica and phenylphosphoryl dichloride to tetrahydrofuran solvent, stir to dissolve, then add catalyst triethylamine dropwise in a mass ratio of 100:22:18, react at 5°C for 12 h, centrifuge, and wash with ethanol and acetone to obtain phosphoryl chloride silica.

[0031] (3) Add phosphoryl chloride silica and piperazine to chloroform solvent, stir to dissolve, then add catalyst triethylamine dropwise, react at 20 °C for 18 h, add diphenylphosphine chloride after the reaction is completed, the mass ratio of phosphoryl chloride silica, piperazine and triethylamine is 100:12:35, react at 20 °C for 12 h, centrifuge, wash with dichloromethane and ethanol, and obtain phosphoryl chloride-piperazine modified functionalized nano-silica.

[0032] (4) Low-density polyethylene, functionalized nano-silica, antioxidant 1010, and lubricant calcium stearate in a mass ratio of 100:1:0.3:0.4 were placed in a twin-screw extruder, melt-blended at 165°C, extruded into granules at 175°C, and then the masterbatch was placed in a film blowing machine for film blowing to produce functionalized nano-silica flame-retardant modified polyethylene packaging bags.

[0033] Example 3

[0034] (1) Add ethanol and nano-silica to deionized water, add N-[3-(trimethoxysilyl)propyl]ethylenediamine after ultrasonic dispersion, the mass ratio of the two is 100:5, react at 70 °C for 3 h, centrifuge and wash with ethanol to obtain amino silica.

[0035] (2) Add amino-modified nano-silica and phenylphosphoryl dichloride to tetrahydrofuran solvent, stir to dissolve, then add catalyst triethylamine dropwise in a mass ratio of 100:28:25, react at 5°C for 8 h, centrifuge, and wash with ethanol and acetone to obtain phosphoryl chloride silica.

[0036] (3) Add phosphoryl chloride silica and piperazine to chloroform solvent, stir to dissolve, then add catalyst triethylamine dropwise, react at 25 °C for 18 h, and then add diphenylphosphine chloride after the reaction is completed. The mass ratio of phosphoryl chloride silica, piperazine and triethylamine is 100:20:55. React at 20 °C for 24 h, centrifuge, wash with dichloromethane and ethanol to obtain phosphoryl chloride-piperazine modified functionalized nano-silica.

[0037] (4) Low-density polyethylene, functionalized nano-silica, antioxidant 1010, and lubricant calcium stearate in a mass ratio of 100:2:0.4:0.55 were placed in a twin-screw extruder, melt-blended at 165°C, extruded into granules at 175°C, and then the masterbatch was placed in a film blowing machine for film blowing to produce functionalized nano-silica flame-retardant modified polyethylene packaging bags.

[0038] Example 4

[0039] (1) Add ethanol and nano-silica to deionized water, add N-[3-(trimethoxysilyl)propyl]ethylenediamine after ultrasonic dispersion, the mass ratio of the two is 100:6.5, react at 70 °C for 4 h, centrifuge and wash with ethanol to obtain amino silica.

[0040] (2) Add amino-modified nano-silica and phenylphosphoryl dichloride to tetrahydrofuran solvent, stir to dissolve, then add catalyst triethylamine dropwise in a mass ratio of 100:32:28, react at 5°C for 10 h, centrifuge, and wash with ethanol and acetone to obtain phosphoryl chloride silica.

[0041] (3) Add phosphoryl chloride silica and piperazine to chloroform solvent, stir to dissolve, then add catalyst triethylamine dropwise, react at 20 °C for 18 h, and then add diphenylphosphine chloride after the reaction is completed. The mass ratio of phosphoryl chloride silica, piperazine and triethylamine is 100:25:65. React at 30 °C for 24 h, centrifuge, wash with dichloromethane and ethanol to obtain phosphoryl chloride-piperazine modified functionalized nano-silica.

[0042] (4) Low-density polyethylene, functionalized nano-silica, antioxidant 1010, and lubricant calcium stearate in a mass ratio of 100:2.2:0.45:0.65 were placed in a twin-screw extruder, melt-blended at 170°C, extruded into granules at 170°C, and then the masterbatch was placed in a film blowing machine for film blowing to produce functionalized nano-silica flame-retardant modified polyethylene packaging bags.

[0043] Example 5

[0044] (1) Add ethanol and nano-silica to deionized water, add N-[3-(trimethoxysilyl)propyl]ethylenediamine after ultrasonic dispersion, the mass ratio of the two is 100:8, react at 80 °C for 4 h, centrifuge and wash with ethanol to obtain amino silica.

[0045] (2) Add amino-modified nano-silica and phenylphosphoryl dichloride to tetrahydrofuran solvent, stir to dissolve, then add catalyst triethylamine dropwise in a mass ratio of 100:40:35, react at 10 °C for 12 h, centrifuge, and wash with ethanol and acetone to obtain phosphoryl chloride silica.

[0046] (3) Add phosphoryl chloride silica and piperazine to chloroform solvent, stir to dissolve, then add catalyst triethylamine dropwise, react at 30 °C for 24 h, and then add diphenylphosphine chloride after the reaction is completed. The mass ratio of phosphoryl chloride silica, piperazine and triethylamine is 100:30:85. React at 30 °C for 36 h, centrifuge, wash with dichloromethane and ethanol to obtain phosphoryl chloride-piperazine modified functionalized nano-silica.

[0047] (4) Low-density polyethylene, functionalized nano-silica, antioxidant 1010, and lubricant calcium stearate in a mass ratio of 100:3:0.6:0.8 were placed in a twin-screw extruder, melt-blended at 170°C, extruded into granules at 175°C, and then the masterbatch was placed in a film blowing machine for film blowing to produce functionalized nano-silica flame-retardant modified polyethylene packaging bags.

[0048] Comparative Example 1 (1) Add ethanol and nano-silica to deionized water, add N-[3-(trimethoxysilyl)propyl]ethylenediamine after ultrasonic dispersion, the mass ratio of the two is 100:4, react at 70 °C for 4 h, centrifuge and wash with ethanol to obtain amino silica.

[0049] (2) Add amino-modified nano-silica and phenylphosphoryl dichloride to tetrahydrofuran solvent, stir to dissolve, then add catalyst triethylamine dropwise in a mass ratio of 100:28:25, react at 0°C for 12 h, centrifuge, and wash with ethanol and acetone to obtain phosphoryl chloride silica.

[0050] (3) Low-density polyethylene, silicon dioxide phosphate chloride, antioxidant 1010, and lubricant calcium stearate in a mass ratio of 100:2:0.42:0.55 were placed in a twin-screw extruder, melt-blended at 165°C, extruded into granules at 175°C, and then the masterbatch was placed in a film blowing machine for film blowing to produce a silicon dioxide phosphate chloride modified polyethylene packaging bag.

[0051] The functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bags in Examples 1-5 and the phosphorus chloride silica modified polyethylene packaging bags in Comparative Example 1 were respectively tested for flame retardancy in a horizontal and vertical combustion test chamber, and the test standard was UL-94 fire rating.

Claims

1. A functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag, characterized in that: The method for preparing the functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag comprises the following steps: (1) Add ethanol and nano-silica to deionized water, add N-[3-(trimethoxysilyl)propyl]ethylenediamine after ultrasonic dispersion, react at 60-80°C for 2-4 hours, centrifuge, and wash with ethanol to obtain amino-silica; (2) adding amino-modified nano-silica and phenylphosphoryl dichloride to tetrahydrofuran solvent, stirring to dissolve, then dropping catalyst triethylamine, reacting, centrifuging, washing with ethanol and acetone, to obtain phosphoryl chloride silica; (3) adding phosphoryl chloride silica and piperazine to chloroform solvent, stirring to dissolve, then dropping catalyst triethylamine to react, adding diphenylphosphine chloride after the reaction is completed, reacting, centrifuging, washing with dichloromethane and ethanol, and obtaining phosphoryl chloride-piperazine modified functionalized nano-silica; (4) Low-density polyethylene, functionalized nano-silica, antioxidant 1010, and lubricant calcium stearate are placed in a twin-screw extruder, melt-blended, and extruded into granules. The masterbatch is then placed in a film blowing machine for film blowing to produce a functionalized nano-silica flame-retardant modified polyethylene packaging bag.

2. The functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag according to claim 1, characterized in that: The mass ratio of nano-silica to N-[3-(trimethoxysilyl)propyl]ethylenediamine in step (1) is 100:3-8.

3. The functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag according to claim 1, characterized in that: The mass ratio of the amino-modified nano-silica, phenylphosphoryl dichloride and triethylamine in the step (2) is 100:15-40:12-35.

4. The functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag according to claim 1, characterized in that: The reaction in step (2) is carried out at 0-10°C for 6-12 hours.

5. The functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag according to claim 1, characterized in that: The mass ratio of silicon dioxide, piperazine and triethylamine in the step (3) is 100:8-30:22-85.

6. The functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag according to claim 1, characterized in that: The reaction in step (3) is carried out at 15-30°C for 12-24 hours.

7. The functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag according to claim 1, characterized in that: The reaction in step (3) is carried out at 15-30°C for 12-36 hours.

8. The functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag according to claim 1, characterized in that: The mass ratio of low-density polyethylene, functionalized nano-silicon dioxide, antioxidant 1010, and calcium stearate in step (4) is 100:0.5-3:0.2-0.6:0.25-0.

8.

9. The functionalized nano-silicon dioxide flame retardant modified polyethylene packaging bag according to claim 1, characterized in that: The melt blending temperature in step (4) is 160-170°C, and the extrusion temperature is 170-175°C.

Images