Antistatic PE composite protective film and preparation method thereof

Abstract

This invention relates to the field of polyethylene technology and discloses an antistatic PE composite protective film and its preparation method. The invention involves mixing polyethylene, polyethylene terephthalate (PET), doped polyaniline, and an antioxidant, then melting and extruding the mixture using a screw extruder. The mixture is then granulated, and the granules are blown into a film using a blown film machine to obtain the antistatic PE composite protective film. The doped polyaniline exhibits excellent compatibility with both polyethylene and PET, and is uniformly dispersed in the PE / PET composite film, ensuring good tensile strength and elongation at break. The protonated polyaniline forms a conductive emerald green imine salt structure, creating a continuous conductive network in the composite film, reducing the volume resistivity of the film material, and resulting in excellent antistatic properties.

Description

Technical Field

[0001] This invention relates to the field of polyethylene technology, specifically to an antistatic PE composite protective film and its preparation method. Background Technology

[0002] Polyethylene is a common polymer resin with high transparency, strong toughness, low water permeability, and good corrosion resistance, and is widely used in packaging films, mulch films, and protective films. However, polyethylene has relatively low strength and is prone to breakage when subjected to tensile stress, affecting its protective performance. Furthermore, polyethylene has low resistivity and poor antistatic properties. Currently, the reinforcement and antistatic modification of polyethylene is a research hotspot.

[0003] Ethylene terephthalate (PET) has high mechanical strength and strong high-temperature resistance. When combined with materials such as polyethylene, polycarbonate, and ABS, it can improve the mechanical and heat resistance properties of the materials. Polyaniline (PO) has high strength and corrosion resistance, and its conductivity is significantly improved after acid doping, making it widely used in antistatic plastics and anti-corrosion coatings. Patent CN120757903B discloses an antistatic plastic packaging film and its preparation process, using dodecyl succinic anhydride esterified phenolic resin as a protonic acid, which is doped into polyaniline, exhibiting good compatibility with polyethylene and providing a certain reinforcing effect. However, this patent does not improve the compatibility between polyaniline and PET, which may affect the performance of PET. Summary of the Invention

[0004] (I) Technical problem to be solved: In view of the shortcomings of the prior art, the present invention provides an antistatic PE composite protective film and its preparation method, which solves the problems of poor antistatic and mechanical strength properties of polyethylene film.

[0005] (ii) The technical solution adopted is: an antistatic PE composite protective film, comprising polyethylene, polyethylene terephthalate, doped polyaniline, and antioxidant in a ratio of (75-90)g:(10-25)g:(4-10)g:(0.1-0.2)g.

[0006] Preparation method of antistatic PE composite protective film: (1) Toluene, monomethyl terephthalate, alkyl glycidyl ether and triphenylmethyl phosphorus iodide were added to a flask equipped with a reflux condenser and reacted. The mixture was then rotary evaporated and the crude product was purified by column chromatography to obtain the dopant precursor.

[0007] (2) Add 1,4-dioxane, the dopant precursor, 1,3-propanesulfonate lactone, sodium hydroxide, and water to a flask, and react. Add hydrochloric acid dropwise, then add saturated sodium chloride aqueous solution and dichloromethane. Shake and extract, rotary evaporate the organic layer, and purify the crude product by column chromatography to obtain the terephthalic acid sulfonic acid dopant. The preparation reaction formula is: .

[0008] (3) Add water and terephthalic acid sulfonic acid dopant to the flask, stir, add polyaniline, heat and stir to dope, cool in an ice water bath, filter, wash with water, and dry to obtain doped polyaniline.

[0009] (4) Mix polyethylene, polyethylene terephthalate, doped polyaniline and antioxidant, melt extrude through a screw extruder, granulate, and blow film the granules through a blown film machine to obtain an antistatic PE composite protective film.

[0010] Furthermore, in (1), the ratio of monomethyl terephthalate, alkyl glycidyl ether, and triphenylmethyl phosphorus iodide is (1.8-2) mol: 1 mol: (3-4) mmol.

[0011] Furthermore, the structural formula of the alkyl glycidyl ether in (1) is: , where a is any integer from 12 to 18.

[0012] Furthermore, in (1), the reaction temperature is 100-110℃ and the reaction time is 5-8h.

[0013] Furthermore, in (2), the ratio of dopant precursor, 1,3-propanesulfonate lactone, and sodium hydroxide is 1 mol: (1-1.1) mol: (1-1.1) mol.

[0014] Furthermore, (2) the reaction temperature is 70-80℃ and the reaction time is 4-6h.

[0015] Furthermore, (2) the reaction temperature is 70-80℃ and the reaction time is 4-6h.

[0016] Furthermore, in (2), hydrochloric acid is added dropwise to adjust the pH to 4-5.

[0017] Furthermore, in (3), the heating temperature is 50-60℃ and the doping time is 6-12h.

[0018] Furthermore, in (3), the ratio of terephthalic acid sulfonic acid dopant to polyaniline is (0.1-0.3) mol: 100g.

[0019] Furthermore, in (4), the temperature of each section of the screw extruder is 190-260℃, and the screw speed is 30-50r / min.

[0020] Furthermore, (4) the temperature of each section of the blown film machine is 260-280℃.

[0021] (III) Beneficial technical effects: Polyaniline is doped with sulfonic acid groups added to terephthalate sulfonic acid dopant to obtain doped polyaniline, which is then blended with polyethylene and polyethylene terephthalate to form a film. The doped polyaniline introduces a long carbon chain similar to polyethylene and a terephthalate structure similar to PET, which significantly improves the compatibility between doped polyaniline and polyethylene and PET. It can be uniformly dispersed in PE / PET composite film, so that the composite protective film maintains good tensile strength and elongation at break.

[0022] The protonated polyaniline of this invention forms a conductive emerald green imine salt structure, which forms a continuous conductive network in the composite film, reducing the volume resistivity of the film material and providing excellent antistatic properties. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0024] The following low-density polyethylene (LDPE) grades are: Formosa Plastics LLDPE 3228, Shenzhen Zhengfangyuan Plastics; Polyethylene terephthalate (PET), 99% purity, Dongguan Kaixingrui Plastic Raw Materials; Polyaniline (intrinsic state), Wuhan Smike Biotechnology.

[0025] Example 1: A method for preparing an antistatic PE composite protective film: (1) Add 15 mL toluene, 50 mmol monomethyl terephthalate, 25 mmol cetyl glycidyl ether, and 0.08 mmol triphenylmethyl phosphorus iodide catalyst to a flask equipped with a reflux condenser. Heat to 110 °C and stir for 5 h. Then evaporate by rotary evaporation. The crude product is purified by column chromatography and eluted with ethyl acetate-petroleum ether solution to obtain the dopant precursor.

[0026] (2) Add 100 mL of 1,4-dioxane, 20 mmol of dopant precursor, 20 mmol of 1,3-propanesulfonate lactone, 20 mmol of sodium hydroxide and 15 mL of water to the flask, heat to 70 °C, stir for 5 h, add hydrochloric acid to adjust pH to 4, add saturated sodium chloride aqueous solution and dichloromethane, shake to extract, evaporate the organic layer by rotary evaporation, separate and purify the crude product by column chromatography, and elute with ethyl acetate-petroleum ether solution to obtain terephthalic acid sulfonic acid dopant.

[0027] (3) Add 120 mL of water and 15 mmol of terephthalic acid sulfonic acid dopant to the flask, stir, add 15 g of polyaniline, heat to 60 °C, stir rapidly for 6 h, cool in an ice water bath, filter, wash with water, and dry to obtain doped polyaniline.

[0028] (4) Mix 450g polyethylene, 50g polyethylene terephthalate, 20g doped polyaniline and 1g antioxidant 168, melt extrude through a screw extruder, with temperatures of 190℃, 230℃, 250℃, 260℃ and 255℃ in each section and screw speed of 30r / min, granulate, blow film forming through a blown film machine, with temperatures of 260℃, 270℃, 280℃ and 280℃ in each section and blow-up ratio of 3, to obtain an antistatic PE composite protective film.

[0029] Example 2, a method for preparing an antistatic PE composite protective film: (1) Add 50 mL of toluene, 160 mol of monomethyl terephthalate, 80 mmol of octadecyl glycidyl ether, and 0.24 mmol of triphenylmethyl phosphorus iodide catalyst to a flask equipped with a reflux condenser. Heat to 100 °C and stir for 8 h. Then evaporate by rotary evaporation. The crude product is purified by column chromatography and eluted with ethyl acetate-petroleum ether solution to obtain the dopant precursor.

[0030] (2) Add 450 mL of 1,4-dioxane, 70 mmol of dopant precursor, 77 mol of 1,3-propanesulfonate lactone, 77 mmol of sodium hydroxide, and 50 mL of water to a flask. Heat to 70 °C and stir for 6 h. Add hydrochloric acid to adjust the pH to 4. Add saturated sodium chloride aqueous solution and dichloromethane. Shake and extract. Rotary evaporate the organic layer. The crude product is separated and purified by column chromatography and eluted with ethyl acetate-petroleum ether solution to obtain terephthalic acid sulfonic acid dopant.

[0031] (3) Add 250 mL of water and 50 mmol of terephthalic acid sulfonic acid dopant to the flask, stir, add 25 g of polyaniline, heat to 50 °C, stir rapidly for 12 h, cool in an ice water bath, filter, wash with water, and dry to obtain doped polyaniline.

[0032] (4) Mix 410g polyethylene, 90g polyethylene terephthalate, 35g doped polyaniline and 1g antioxidant 168, melt extrude through a screw extruder, with temperatures of 190℃, 230℃, 250℃, 260℃ and 255℃ in each section and screw speed of 50r / min, granulate, blow film forming through a blown film machine, with temperatures of 260℃, 270℃, 280℃ and 280℃ in each section and blow-up ratio of 3, to obtain an antistatic PE composite protective film.

[0033] Example 3, a method for preparing an antistatic PE composite protective film: (1) Add 75 mL of toluene, 0.216 mol of monomethyl terephthalate, 0.12 mol of dodecyl glycidyl ether, and 0.48 mmol of triphenylmethyl phosphorus iodide catalyst to a flask equipped with a reflux condenser. Heat to 110 °C and stir for 6 h. Then evaporate by rotary evaporation. The crude product is purified by column chromatography and eluted with ethyl acetate-petroleum ether solution to obtain the dopant precursor.

[0034] (2) Add 600 mL of 1,4-dioxane, 0.1 mol of dopant precursor, 0.1 mol of 1,3-propanesulfonate lactone, 0.1 mol of sodium hydroxide, and 80 mL of water to a flask. Heat to 80 °C and stir for 4 h. Add hydrochloric acid to adjust the pH to 5. Add saturated sodium chloride aqueous solution and dichloromethane. Shake and extract. Rotary evaporate the organic layer. The crude product is separated and purified by column chromatography and eluted with ethyl acetate-petroleum ether solution to obtain terephthalic acid sulfonic acid dopant.

[0035] (3) Add 300 mL of water and 90 mmol of terephthalic acid sulfonic acid dopant to the flask, stir, add 30 g of polyaniline, heat to 60 °C, stir rapidly for 10 h, cool in an ice water bath, filter, wash with water, and dry to obtain doped polyaniline.

[0036] (4) Mix 375g polyethylene, 125g polyethylene terephthalate, 50g doped polyaniline and 0.5g antioxidant 168, melt extrude through a screw extruder, with temperatures of 190℃, 230℃, 250℃, 260℃ and 255℃ for each section and screw speed of 50r / min, granulate, and blown into film by a blown film machine, with temperatures of 260℃, 270℃, 280℃ and 280℃ for each section and blown ratio of 3 to obtain an antistatic PE composite protective film.

[0037] Comparative Example 1: A method for preparing a PE composite protective film: (1) Mix 450g polyethylene, 50g polyethylene terephthalate and 1g antioxidant 168, melt extrude through a screw extruder, with temperatures of 190℃, 230℃, 250℃, 260℃ and 255℃ in each section, and screw speed of 30r / min. Cut into pellets, blown into film by a blown film machine, with temperatures of 260℃, 270℃, 280℃ and 280℃ in each section, and blown up to 3, to obtain a PE composite protective film.

[0038] Comparative Example 2: A method for preparing a PE composite protective film: (1) Add 120 mL of water and 15 mmol of dodecylbenzenesulfonic acid to the flask, stir, add 15 g of polyaniline, heat to 60 °C, stir rapidly for 6 h, cool in an ice water bath, filter, wash with water, and dry to obtain doped polyaniline.

[0039] (2) Mix 450g polyethylene, 50g polyethylene terephthalate, 20g doped polyaniline and 1g antioxidant 168, melt extrude through a screw extruder, with temperatures of 190℃, 230℃, 250℃, 260℃ and 255℃ in each section and screw speed of 30r / min, granulate, and blow film forming through a blown film machine, with temperatures of 260℃, 270℃, 280℃ and 280℃ in each section and blow-up ratio of 3 to obtain PE composite protective film.

[0040] Comparative Example 3: A method for preparing a PE composite protective film: (1) Add 120 mL of water and 15 mmol of dopant precursor (prepared according to the method of Example 1) to a flask, stir, add 15 g of polyaniline, heat to 60 °C, stir rapidly for 6 h, cool in an ice water bath, filter, wash with water, and dry to obtain doped polyaniline.

[0041] (2) Mix 450g polyethylene, 50g polyethylene terephthalate, 20g doped polyaniline and 1g antioxidant 168, melt extrude through a screw extruder, with temperatures of 190℃, 230℃, 250℃, 260℃ and 255℃ in each section and screw speed of 30r / min, granulate, blow film forming through a blown film machine, with temperatures of 260℃, 270℃, 280℃ and 280℃ in each section and blow-up ratio of 3 to obtain PE composite protective film.

[0042] Comparative Example 4: A method for preparing a PE composite protective film: (1) Add 15 mL of toluene, 50 mmol of benzoic acid, 25 mmol of cetyl glycidyl ether, and 0.08 mmol of triphenylmethyl phosphorus iodide catalyst to a flask equipped with a reflux condenser. Heat to 110 °C and stir for 5 h. Rotary evaporate the mixture. The crude product is purified by column chromatography and eluted with ethyl acetate-petroleum ether solution to obtain the dopant precursor, with the following structural formula: .

[0043] (2) Add 100 mL of 1,4-dioxane, 20 mmol of dopant precursor, 20 mmol of 1,3-propanesulfonate lactone, 20 mmol of sodium hydroxide, and 15 mL of water to a flask. Heat to 70 °C and stir for 5 h. Adjust the pH to 4 by adding hydrochloric acid dropwise. Add saturated sodium chloride aqueous solution and dichloromethane. Shake and extract. Rotary evaporate the organic layer. The crude product is purified by column chromatography to obtain the sulfonic acid dopant, with the following structural formula: .

[0044] (3) Add 120 mL of water and 15 mmol of sulfonic acid dopant to the flask, stir, add 15 g of polyaniline, heat to 60 °C, stir rapidly for 6 h, cool in an ice water bath, filter, wash with water, and dry to obtain doped polyaniline.

[0045] (4) Mix 450g polyethylene, 50g polyethylene terephthalate, 20g doped polyaniline and 1g antioxidant 168, melt extrude through a screw extruder, with temperatures of 190℃, 230℃, 250℃, 260℃ and 255℃ in each section and screw speed of 30r / min, granulate, blow film forming through a blown film machine, with temperatures of 260℃, 270℃, 280℃ and 280℃ in each section and blow-up ratio of 3 to obtain PE composite protective film.

[0046] The tensile properties of the membrane material were tested according to standard GB / T 1040.3-2006. The volume resistivity was tested according to the method in standard GB / T 1410-2006. Table 1 Performance Tests Example 1 uses doped polyaniline as an antistatic agent, added to a blend of polyethylene (PE) and polyethylene terephthalate (PET) to obtain an antistatic PE composite protective film. After being doped with sulfonic acid groups by a terephthalate sulfonic acid dopant, polyaniline introduces a long carbon chain similar to polyethylene and a terephthalate structure similar to PET, significantly improving the compatibility between the doped polyaniline and polyethylene and PET. This allows it to be uniformly dispersed in the PE / PET composite film, maintaining excellent tensile strength and elongation at break, significantly higher than Comparative Example 1. Furthermore, the protonated polyaniline forms a conductive emerald green imine salt structure, creating a continuous conductive network in the composite film, reducing the volume resistivity of the film material significantly lower than Comparative Example 1, and exhibiting excellent antistatic properties. Examples 2 and 3, by adjusting the proportions of each component, also prepared protective films with excellent tensile and antistatic properties.

[0047] Comparative Example 2 uses conventional dodecylbenzenesulfonic acid to dope polyaniline, which does not contain terephthalate structure. The doped polyaniline has poor compatibility with PET and cannot be well dispersed in the composite protective film matrix, resulting in poor tensile properties of the composite protective film, a higher volume resistivity than in Example 1, and poor antistatic properties.

[0048] The dopant precursor in Comparative Example 3 does not contain sulfonic acid groups and cannot interact with polyaniline, so no doping occurs. After washing, the dopant precursor is easily washed away. The polyaniline does not have long carbon chains and terephthalate structures, resulting in poor compatibility between polyaniline and PE and PET, which seriously affects the mechanical properties of the composite film. The undoped polyaniline has low conductivity, the composite film has a high volume resistivity, and poor antistatic properties.

[0049] The sulfonic acid dopant in Comparative Example 4 has a lower ester group content, and the compatibility between the doped polyaniline and PET is lower than that in Example 1, resulting in lower tensile properties of the composite film and higher volume resistivity than in Example 1.

[0050] The above are merely embodiments of the present invention and are not intended to limit the invention. Those skilled in the art will recognize that the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An antistatic PE composite protective film, characterized in that, The antistatic PE composite protective film comprises polyethylene, polyethylene terephthalate, doped polyaniline, and antioxidant in a ratio of (75-90)g:(10-25)g:(4-10)g:(0.1-0.2)g.

2. A method for preparing an antistatic PE composite protective film as described in claim 1, characterized in that, The preparation method is as follows: S1. Add water and terephthalic acid sulfonic acid dopant to a flask, stir, add polyaniline, heat and stir to dope, cool in an ice water bath, filter, wash with water, and dry to obtain doped polyaniline. The structural formula of the terephthalate sulfonic acid dopant is as follows: , where a is any integer from 12 to 18; S2. Mix polyethylene, polyethylene terephthalate, doped polyaniline, and antioxidant, melt-extrude the mixture through a screw extruder, granulate it, and blow-dry the granules through a blown film machine to obtain an antistatic PE composite protective film.

3. The method for preparing the antistatic PE composite protective film according to claim 2, characterized in that, The heating temperature in S1 is 50-60℃, and the doping time is 6-12h.

4. The method for preparing the antistatic PE composite protective film according to claim 2, characterized in that, The ratio of terephthalate sulfonic acid dopant to polyaniline in S1 is (0.1-0.3) mol: 100g.

5. The method for preparing the antistatic PE composite protective film according to claim 2, characterized in that, The preparation method of the terephthalate sulfonic acid dopant is as follows: (1) Add toluene, monomethyl terephthalate in a ratio of (1.8-2) mol: 1 mol: (3-4) mmol, alkyl glycidyl ether, and triphenylmethyl phosphorus iodide to a flask equipped with a reflux condenser. Heat to 100-110℃, stir for 5-8 h, evaporate by rotary evaporation, and purify the crude product by column chromatography to obtain the dopant precursor. (2) Add 1,4-dioxane, a dopant precursor in a ratio of 1 mol:(1-1.1) mol:(1-1.1) mol, 1,3-propanesulfonic acid lactone, sodium hydroxide, and water to a flask, heat to 70-80℃, stir for 4-6 h, add hydrochloric acid to adjust the pH to 4-5, add saturated sodium chloride aqueous solution and dichloromethane, shake to extract, rotary evaporate the organic layer, and separate and purify the crude product by column chromatography to obtain terephthalic acid sulfonic acid dopant.

6. The method for preparing the antistatic PE composite protective film according to claim 6, characterized in that, The structural formula of the alkyl glycidyl ether in (1) is as follows: , where a is any integer from 12 to 18.

7. The method for preparing the antistatic PE composite protective film according to claim 2, characterized in that, The temperature of each section of the screw extruder in S2 is 190-260℃, and the screw speed is 30-50 r / min.

8. The method for preparing the antistatic PE composite protective film according to claim 2, characterized in that, The temperature of each section of the blown film machine in S2 is 260-280℃.

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