High-ductility PET (Polyethylene Terephthalate) film

Abstract

The invention discloses a high-ductility PET film and a preparation method thereof. The PET film is prepared from the following raw materials in parts by weight: 60-80 parts of PET resin, 3-5 parts of polyethylene glycol, 5-15 parts of filler, 1-3 parts of a stabilizer, 1-2 parts of a phosphorylated chitosan / modified zinc oxide nanoparticle compound, 0.5-5 parts of a dispersing agent and 0.5-2 parts of an antioxidant. The PET resin is used as a base material, the filler, the stabilizer, the phosphorylated chitosan / modified zinc oxide nanoparticle compound, the dispersing agent and the antioxidant are added and mixed with the PET resin, and the PET film is prepared through the operation process steps of melt extrusion, cooling, two-way stretching and sizing. And the flame-retardant antibacterial plastic has excellent flame retardance and antibacterial property. The preparation method disclosed by the invention is simple in process, easy to operate and favorable for reducing the production cost.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a highly ductile PET film. Background Art

[0002] PET film, also known as polyester film, has good transparency, airtightness, and mechanical properties. Its toughness is the best among all thermoplastic plastic films. It has moderate moisture resistance, high gloss, and good heat resistance, cold resistance, oil resistance, chemical stability, and dimensional stability. It is widely used in magnetic recording, photosensitive materials, electronics, printing, electrical insulation, packaging and decoration, screen protection and other fields.

[0003] Due to the good insulation performance of PET film, it is often used to prepare the backsheet film of solar panels. The common backsheet film of solar panels on the market has a three-layer structure (PVDF / PET / PVDF), thus improving the performance and durability of solar panels. However, ordinary PET film has the problem of being easily decomposed by microorganisms. When the PET film is decomposed and corroded by microorganisms and damaged, the waterproof property of the solar backsheet film will be greatly reduced, and the solar panel is very likely to have a dangerous situation of short circuit and fire. In addition, the present invention also finds that ordinary PET film has insufficient ductility. In the lamination process of composite materials, it may lead to uneven interfacial bonding or local stress concentration, affecting the mechanical properties of the final product. Moreover, the low ductility of PET film may also cause cracks or fatigue failure due to insufficient ductility in deep drawing or high-frequency bending scenarios (such as flexible electronics, foldable packaging), restricting its application in fields that require high deformation or complex forming processes. Therefore, a PET film with high ductility, excellent antibacterial property, and flame retardancy is needed.

[0004] CN117624851A discloses a high-strength polyester film and its preparation method. The high-strength polyester film provided by this invention is made from the following raw materials in parts by weight: 40-50 parts of PET resin, 20-30 parts of PBT resin, 10-20 parts of functional polyester-based polycondensate, 5-8 parts of glass fiber, 6-8 parts of disodium 3,3-disulfonic acid-4,4-difluorophenyl sulfone, 0.5-1 part of antioxidant, 1-2 parts of plasticizer, 0.3-0.6 part of lubricant, and 0.5-1 part of stabilizer. This high-strength polyester film has excellent mechanical and mechanical properties, good aging resistance, flame retardancy, and high-temperature resistance, but its antibacterial property is poor, and it is easily decomposed and corroded by microorganisms, affecting its overall performance.

[0005] CN114085502A discloses a flame-retardant and antibacterial PET film and its production process. The flame-retardant and antibacterial PET film provided by the invention has the following component ratios by mass percentage: polyethylene terephthalate 50%-90%, flame-retardant and antibacterial agent 5%-30%, ultraviolet absorber 0.5%-7%, antioxidant 0.5%-3%, heat-resistant agent 4%-10%. Its production process includes the following steps: preparing a flame-retardant and antibacterial agent; mixing materials; drying treatment; melt-extruding and casting into a thick sheet; biaxially stretching the cast sheet to obtain a film; winding and slitting the film. The PET film provided by the invention has good antibacterial and flame-retardant effects, but its ductility is poor. Summary of the Invention

[0006] In view of the above-mentioned defects of the prior art, the present invention provides a high-ductility PET film and its preparation method. The PET film provided by the present invention not only has high ductility, excellent flame retardancy and antibacterial properties, which is beneficial to inhibiting the aggregation and reproduction of microorganisms on the surface of the PET film and can prevent the solar panel from burning, but also the preparation method of the present invention has a simple process, is easy to operate, and helps to reduce production costs.

[0007] To achieve the above object, the present invention provides a high-ductility PET film, and the film comprises the following raw materials in parts by weight:

[0008] 60-80 parts of PET resin, 3-5 parts of polyethylene glycol, 5-15 parts of filler, 1-3 parts of stabilizer, 1-2 parts of phosphorylated chitosan / modified zinc oxide nanoparticle composite, 0.5-5 parts of dispersant, 0.5-2 parts of antioxidant.

[0009] Preferably, the phosphorylated chitosan / modified zinc oxide nanoparticle composite is obtained by surface-modifying zinc oxide nanoparticles with a silane coupling agent, phosphorylating and grafting chitosan with orthophosphoric acid, and finally compounding phosphorylated chitosan and modified zinc oxide in an acidic solution by ultrasonic assistance.

[0010] Preferably, the stabilizer is at least one of calcium stearate, triphenyl phosphate, and trimethyl phosphate.

[0011] Preferably, the dispersant is selected from at least one of polyethylene wax, paraffin wax, and ethylene bisoleamide.

[0012] Preferably, the antioxidant is selected from at least one of tea polyphenols, tocopherols, 2-hydroxyacetophenone, butylated hydroxyanisole, dibutylhydroxytoluene, and tert-butylhydroquinone.

[0013] Preferably, the preparation method of the phosphorylated chitosan / modified zinc oxide nanoparticle composite comprises the following steps, by weight:

[0014] S1. Mix 1.8 - 2.2 parts of ethyl acetate and 4.5 - 4.7 parts of 3 - isocyanatopropyltriethoxysilane, then add 0.03 - 0.04 parts of dibutyltin dilaurate, and mix and stir at 40 - 45 °C for 3 - 5 h to obtain a mixed solution; Add 0.65 - 0.75 parts of the mixed solution and 1.8 - 2.2 parts of zinc oxide nanoparticles into a mixed system composed of 195 - 205 parts of anhydrous ethanol and water mixed by a volume ratio of 2 - 2.2:1, and perform ultrasonic treatment for 0.5 - 1 h under the conditions of an ultrasonic frequency of 30 - 50 KHz and an ultrasonic power of 50 - 100 W; Adjust the pH of the solution to 9.5 - 10.5 with 0.5 - 1 mol / L NaOH aqueous solution, and continue to mix and stir and react in an oil bath at 60 - 65 °C and 400 - 600 rpm for 10 - 15 h; Wash the reaction product 2 - 3 times with anhydrous ethanol and water respectively, filter, and dry to obtain modified zinc oxide nanoparticles;

[0015] S2. Add 8 - 12 parts of chitosan, 18 - 22 parts of orthophosphoric acid, and 90 - 110 parts of urea into 200 parts of N,N - dimethylformamide, and mix and stir at 145 - 155 °C for 0.5 - 2 h under nitrogen gas protection; After cooling, filter, collect the precipitate, wash it 3 times with water, and then dry it at 55 - 65 °C for 22 - 25 h to obtain phosphorylated chitosan;

[0016] S3. Add 1.8 - 2.1 parts of phosphorylated chitosan into 95 - 105 parts of 0.2 - 0.5 mol / L acetic acid solution and mix and stir for 8 - 12 h to obtain a mixed solution; Then add 0.1 - 0.5 parts of modified zinc oxide nanoparticles, and perform ultrasonic treatment for 20 - 40 min under the conditions of an ultrasonic frequency of 30 - 50 KHz and an ultrasonic power of 50 - 100 W; Centrifuge, collect the solid, wash it 2 - 3 times with water and ethanol respectively, and dry to obtain a phosphorylated chitosan / modified zinc oxide nanoparticle composite.

[0017] For further description of the present invention, in the process of phosphorylated chitosan / modified zinc oxide nanoparticle composite, first, 3-isocyanatopropyltriethoxysilane is mixed with nano zinc oxide for reaction. 3-Isocyanatopropyltriethoxysilane is mixed and undergoes a condensation reaction through its siloxy group with the hydroxyl group on the surface of zinc oxide to form a Si-O-Zn bond, thereby grafting 3-isocyanatopropyltriethoxysilane onto the surface of zinc oxide to obtain modified zinc oxide nanoparticles. This process not only improves the dispersibility of zinc oxide but also endows it with better antibacterial properties. Secondly, the amino group in chitosan reacts with phosphoric acid under the catalysis of urea to generate a phosphoester bond, and phosphorylated chitosan is prepared. Then, the modified zinc oxide nanoparticles and phosphorylated chitosan are mixed and subjected to ultrasonic treatment. During the reaction, the hydroxyl group in phosphorylated chitosan forms a hydrogen bond with the siloxy group on the surface of the modified zinc oxide nanoparticles, and through the interaction of hydrogen bonds and van der Waals forces, a stable phosphorylated chitosan / modified zinc oxide nanoparticle composite is formed. The present invention finds that by introducing the prepared phosphorylated chitosan / modified zinc oxide nanoparticle composite into the preparation process of PET films, not only can the flame retardancy and thermal stability of the films be improved, but also it is beneficial to further improve their antibacterial properties.

[0018] Preferably, the filler is selected from at least one of talc and modified attapulgite.

[0019] More preferably, the filler is composed of talc and modified attapulgite mixed in a mass ratio of 1-3:1.

[0020] Preferably, the preparation method of the modified attapulgite includes the following steps, by weight:

[0021] Add 18-22 parts of attapulgite to 190-210 parts of 1-2 mol / L hydrochloric acid aqueous solution and mix evenly. After ultrasonic treatment for 20-40 min, mix and stir at 75-85 °C for 0.5-2 h; centrifuge, collect the precipitate, wash it with water until neutral, and vacuum dry it at 35-45 °C for 22-25 h to obtain acid-activated attapulgite; add 1.8-2.2 parts of the above acid-activated attapulgite and 0.3-0.6 part of the modifier to 45-55 parts of water and mix. Then add 0.05-0.1 part by weight of p-toluenesulfonic acid as a catalyst, and ultrasonically treat it at an ultrasonic frequency of 30-50 KHz and an ultrasonic power of 50-100 W for 20-30 min, and then mix and stir at 80-90 °C for 3-5 h; neutralize the reaction system with 0.5-1 mol / L NaOH aqueous solution to remove the catalyst, and then centrifuge and separate the precipitate, and dry it to obtain modified attapulgite.

[0022] More preferably, the modifier is selected from at least one of lysine, glutamic acid, and leucine.

[0023] As a further illustration of the present invention, during the preparation process of the modified attapulgite, after the attapulgite is acid-activated, its surface is rich in hydroxyl groups. Subsequently, lysine, glutamic acid, and leucine are introduced as modifiers and mixed with it for reaction. Under the action of a catalyst, the carboxyl groups in the modifier structure react with the hydroxyl groups on the surface of the acid-activated attapulgite to form covalent bonds, thereby grafting the modifier onto the surface of the acid-activated attapulgite to obtain modified attapulgite. The present invention discovers that the dispersibility of the modified attapulgite in the PET matrix is significantly improved, without obvious agglomeration. After being mixed with talc powder, which itself has good dispersibility, the synergistic effect of the two further improves the dispersion effect of the filler in the PET matrix, ensuring the uniform distribution of the filler in the PET matrix, avoiding the formation of stress concentration points, and being beneficial to further improving the ductility of the film.

[0024] The present invention also provides a method for preparing the above-mentioned high-ductility PET film, comprising the following steps:

[0025] The PET resin is dried to obtain the dried PET resin; then the dried PET resin is mixed uniformly with polyethylene glycol, filler, stabilizer, phosphorylated chitosan / modified zinc oxide nanoparticle composite, dispersant, and antioxidant, and then fed into a twin-screw extruder for melt extrusion to form a molten film. The screw speed is 100 - 200 rpm, the melting temperature is 260 - 280 °C, and then the molten film is cast onto a cooling roller through a casting die head for cooling. The cooling temperature is 28 - 33 °C to form a cast sheet, and then it is subjected to transverse stretching, longitudinal stretching, and shaping to obtain a high-ductility PET film.

[0026] Preferably, the thickness of the PET film is 30 - 50 μm.

[0027] The beneficial effects of the present invention:

[0028] 1. Compared with the prior art, the high-ductility PET film of the present invention is prepared by reasonably proportioning each raw material component, using PET resin as the base material, adding filler, stabilizer, phosphorylated chitosan / modified zinc oxide nanoparticle composite, dispersant, and antioxidant and mixing them with the PET resin, and through the process steps of melt extrusion, cooling, biaxial stretching, and shaping to obtain the PET film. The prepared PET film has a high elongation at break and tear strength, showing excellent ductility.

[0029] 2. The present invention prepares a phosphorylated chitosan / modified zinc oxide nanoparticle composite by mixing and reacting modified zinc oxide nanoparticles with phosphorylated chitosan, and introduces it into the preparation process of a highly ductile PET film. At the same time, talcum powder and modified attapulgite are mixed as fillers and used synergistically therewith, so that the prepared PET film not only has good flame retardancy and thermal stability, but also its antibacterial property is further improved. Detailed implementation mode

[0030] Parameters and sources of specific chemical substances used.

[0031] PET resin, grade: PET530, brand: Yehong New Materials;

[0032] Polyethylene glycol, molecular weight: 400;

[0033] Talcum powder, particle size: 10μm;

[0034] Attapulgite, mesh number: 325 mesh;

[0035] Chitosan, degree of deacetylation 90%, molecular weight: 50KDa;

[0036] Zinc oxide nanoparticles, particle size: 30nm.

[0037] Example 1

[0038] A preparation method of a highly ductile PET film includes the following steps:

[0039] Dry 70 parts by weight of PET resin to obtain dried PET resin; then mix the dried PET resin with 4 parts by weight of polyethylene glycol, 12 parts by weight of talcum powder, 2 parts by weight of triphenyl phosphate, 1.5 parts by weight of phosphorylated chitosan / modified zinc oxide nanoparticle composite, 3 parts by weight of ethylene bisoleamide, and 1 part by weight of 2-hydroxypropiophenone evenly, and send it into a twin-screw extruder for melt extrusion to form a molten film. The screw speed is 200 rpm, the melting temperature is 280 °C, and then the molten film is cast on a cooling roll through a casting die head for cooling. The cooling temperature is 30 °C to form a cast sheet, and then it is subjected to transverse stretching, longitudinal stretching, and shaping to obtain a highly ductile PET film with a thickness of 35μm.

[0040] The preparation method of the phosphorylated chitosan / modified zinc oxide nanoparticle composite includes the following steps:

[0041] S1. Mix 2 parts by weight of ethyl acetate and 4.6 parts by weight of 3-isocyanatopropyltriethoxysilane, then add 0.035 parts by weight of dibutyltin dilaurate, and mix and stir at 42 °C for 4 h to obtain a mixed solution; add 0.7 parts by weight of the mixed solution and 2 parts by weight of zinc oxide nanoparticles to 200 parts by weight of a mixed system composed of anhydrous ethanol and water in a volume ratio of 2:1, and perform ultrasonic treatment for 1 h under the conditions of an ultrasonic frequency of 40 KHz and an ultrasonic power of 50 W; adjust the pH of the solution to 10 with 1 mol / L NaOH aqueous solution, and continue to mix and stir and react in an oil bath at 62 °C and 500 rpm for 12 h; wash the reaction product 3 times with anhydrous ethanol and water respectively, filter, and dry to obtain modified zinc oxide nanoparticles;

[0042] S2. Add 10 parts by weight of chitosan, 20 parts by weight of orthophosphoric acid, and 100 parts by weight of urea to 200 parts by weight of N,N-dimethylformamide, and mix and stir at 148 °C for 1 h under nitrogen gas protection; after cooling, filter, collect the precipitate, wash it 3 times with water, and then dry it at 60 °C for 24 h to obtain phosphorylated chitosan;

[0043] S3. Add 2 parts by weight of phosphorylated chitosan to 100 parts by weight of a 0.5 mol / L acetic acid solution and mix and stir for 10 h to obtain a mixed solution; then add 0.2 parts by weight of modified zinc oxide nanoparticles, and perform ultrasonic treatment for 30 min under the conditions of an ultrasonic frequency of 40 KHz and an ultrasonic power of 50 W; centrifuge, collect the solid, wash it 3 times with water and ethanol respectively, and dry to obtain a phosphorylated chitosan / modified zinc oxide nanoparticle composite.

[0044] Example 2

[0045] A preparation method of a highly ductile PET film, comprising the following steps:

[0046] Dry 70 parts by weight of PET resin to obtain dried PET resin; then uniformly mix the dried PET resin with 4 parts by weight of polyethylene glycol, 12 parts by weight of modified attapulgite, 2 parts by weight of triphenyl phosphate, 1.5 parts by weight of phosphorylated chitosan / modified zinc oxide nanoparticle composite, 3 parts by weight of ethylene bisoleamide, and 1 part by weight of 2-hydroxyacetophenone, and send it into a twin-screw extruder for melt extrusion to form a molten film. The screw speed is 200 rpm, the melting temperature is 280 °C, and then the molten film is cast on a cooling roll through a casting die head for cooling. The cooling temperature is 30 °C to form a cast sheet, and then a highly ductile PET film is obtained through transverse stretching, longitudinal stretching, and shaping; the thickness of the PET film is 35 μm.

[0047] The preparation method of the phosphorylated chitosan / modified zinc oxide nanoparticle composite is the same as that in Example 1.

[0048] The preparation method of the modified attapulgite includes the following steps:

[0049] Add 20 parts by weight of attapulgite to 200 parts by weight of 2 mol / L hydrochloric acid aqueous solution and mix evenly. After ultrasonic treatment for 30 min, mix and stir at 80 °C for 1 h; centrifuge, collect the precipitate, wash it with water until neutral, and vacuum dry it at 40 °C for 24 h to obtain acid-activated attapulgite; add 2 parts by weight of the above acid-activated attapulgite and 0.5 part by weight of leucine to 50 parts by weight of water and mix. Then add 0.1 part by weight of p-toluenesulfonic acid as a catalyst, and ultrasonic treat it for 20 min under the conditions of ultrasonic frequency of 40 KHz and ultrasonic power of 50 W. Then mix and stir at 85 °C for 4 h; neutralize the reaction system with 1 mol / L NaOH aqueous solution, remove the catalyst, centrifuge and separate the precipitate, and dry it to obtain the modified attapulgite.

[0050] Example 3

[0051] A preparation method of a highly ductile PET film, which is different from Example 2 in that the preparation method of the modified attapulgite includes the following steps:

[0052] Add 20 parts by weight of attapulgite to 200 parts by weight of 2 mol / L hydrochloric acid aqueous solution and mix evenly. After ultrasonic treatment for 30 min, mix and stir at 80 °C for 1 h; centrifuge, collect the precipitate, wash it with water until neutral, and vacuum dry it at 40 °C for 24 h to obtain acid-activated attapulgite; add 2 parts by weight of the above acid-activated attapulgite and 0.5 part by weight of glutamic acid to 50 parts by weight of water and mix. Then add 0.1 part by weight of p-toluenesulfonic acid as a catalyst, and ultrasonic treat it for 20 min under the conditions of ultrasonic frequency of 40 KHz and ultrasonic power of 50 W. Then mix and stir at 85 °C for 4 h; neutralize the reaction system with 1 mol / L NaOH aqueous solution, remove the catalyst, centrifuge and separate the precipitate, and dry it to obtain the modified attapulgite.

[0053] Example 4

[0054] A preparation method of a highly ductile PET film, which is different from Example 2 in that the preparation method of the modified attapulgite includes the following steps:

[0055] Add 20 parts by weight of attapulgite to 200 parts by weight of 2 mol / L hydrochloric acid aqueous solution and mix evenly. After ultrasonic treatment for 30 min, mix and stir at 80 °C for 1 h; centrifuge, collect the precipitate, wash it with water until neutral, and vacuum dry it at 40 °C for 24 h to obtain acid-activated attapulgite; add 2 parts by weight of the above acid-activated attapulgite and 0.5 part by weight of lysine to 50 parts by weight of water and mix. Then add 0.1 part by weight of p-toluenesulfonic acid as a catalyst, and perform ultrasonic treatment at an ultrasonic frequency of 40 KHz and an ultrasonic power of 50 W for 20 min. Then mix and stir at 85 °C for 4 h; neutralize the reaction system with 1 mol / L NaOH aqueous solution, remove the catalyst, centrifuge and separate the precipitate, and dry it to obtain modified attapulgite.

[0056] Example 5

[0057] A preparation method of a highly ductile PET film, comprising the following steps:

[0058] Dry 70 parts by weight of PET resin to obtain dried PET resin; then mix the dried PET resin evenly with 4 parts by weight of polyethylene glycol, 12 parts by weight of filler, 2 parts by weight of triphenyl phosphate, 1.5 parts by weight of phosphorylated chitosan / modified zinc oxide nanoparticle composite, 3 parts by weight of ethylene bisoleamide, and 1 part by weight of 2-hydroxyacetophenone, and then feed it into a twin-screw extruder for melt extrusion to form a molten film. The screw speed is 200 rpm, the melting temperature is 280 °C, and then the molten film is cast on a cooling roll through a casting die head for cooling. The cooling temperature is 30 °C to form a cast sheet, and then it is subjected to transverse stretching, longitudinal stretching, and shaping to obtain a highly ductile PET film; the thickness of the PET film is 35 μm.

[0059] The filler is composed of talc powder and modified attapulgite mixed in a mass ratio of 2:1.

[0060] The preparation method of the modified attapulgite is the same as that in Example 4.

[0061] The preparation method of the phosphorylated chitosan / modified zinc oxide nanoparticle composite is the same as that in Example 1.

[0062] Comparative Example 1

[0063] A preparation method of a highly ductile PET film, comprising the following steps:

[0064] 70 parts by weight of PET resin is dried to obtain the dried PET resin; then the dried PET resin is mixed evenly with 4 parts by weight of polyethylene glycol, 12 parts by weight of filler, 2 parts by weight of triphenyl phosphate, 1.5 parts by weight of phosphorylated chitosan / modified zinc oxide nanoparticle composite, 3 parts by weight of ethylene bisoleamide, and 1 part by weight of 2-hydroxyacetophenone, and then fed into a twin-screw extruder for melt extrusion to form a molten film. The screw speed is 200 rpm and the melting temperature is 280 °C. Then, the molten film is cast on a cooling roller through a casting die head for cooling. The cooling temperature is 30 °C to form a cast sheet, which is then subjected to transverse stretching, longitudinal stretching, and shaping to obtain a highly ductile PET film; the thickness of the PET film is 35 μm.

[0065] The filler is composed of talc and attapulgite mixed in a mass ratio of 2:1.

[0066] The preparation method of the phosphorylated chitosan / modified zinc oxide nanoparticle composite is the same as that in Example 1.

[0067] Comparative Example 2

[0068] A method for preparing a highly ductile PET film, comprising the following steps:

[0069] 70 parts by weight of PET resin is dried to obtain the dried PET resin; then the dried PET resin is mixed evenly with 4 parts by weight of polyethylene glycol, 12 parts by weight of filler, 2 parts by weight of triphenyl phosphate, 1.5 parts by weight of phosphorylated chitosan, 3 parts by weight of ethylene bisoleamide, and 1 part by weight of 2-hydroxyacetophenone, and then fed into a twin-screw extruder for melt extrusion to form a molten film. The screw speed is 200 rpm and the melting temperature is 280 °C. Then, the molten film is cast on a cooling roller through a casting die head for cooling. The cooling temperature is 30 °C to form a cast sheet, which is then subjected to transverse stretching, longitudinal stretching, and shaping to obtain a highly ductile PET film; the thickness of the PET film is 35 μm.

[0070] The filler is composed of talc and modified attapulgite mixed in a mass ratio of 2:1.

[0071] The preparation method of the modified attapulgite is the same as that in Example 4.

[0072] The preparation method of the phosphorylated chitosan comprises the following steps:

[0073] 10 parts by weight of chitosan, 20 parts by weight of orthophosphoric acid, and 100 parts by weight of urea are added to 200 parts by weight of N,N-dimethylformamide, and mixed and stirred at 148 °C for 1 h under nitrogen gas protection; after cooling, filtered, the precipitate is collected, washed with water 3 times, and then dried at 60 °C for 24 h to obtain phosphorylated chitosan.

[0074] Comparative Example 3

[0075] A method for preparing a highly ductile PET film, comprising the following steps:

[0076] 70 parts by weight of PET resin is dried to obtain dried PET resin; then the dried PET resin is mixed evenly with 4 parts by weight of polyethylene glycol, 12 parts by weight of filler, 2 parts by weight of triphenyl phosphate, 1.5 parts by weight of modified zinc oxide nanoparticles, 3 parts by weight of ethylene bisoleamide, and 1 part by weight of 2-hydroxypropiophenone, and then fed into a twin-screw extruder for melt extrusion to form a molten film. The screw speed is 200 rpm, the melting temperature is 280 °C, and then the molten film is cast on a cooling roller through a casting die head for cooling. The cooling temperature is 30 °C to form a cast sheet, and then it is subjected to transverse stretching, longitudinal stretching, and shaping to obtain a highly ductile PET film; the thickness of the PET film is 35 μm.

[0077] The filler is composed of talc powder and modified attapulgite mixed in a mass ratio of 2:1.

[0078] The preparation method of the modified attapulgite is the same as that in Example 4.

[0079] The preparation method of the modified zinc oxide nanoparticles comprises the following steps:

[0080] 2 parts by weight of ethyl acetate and 4.6 parts by weight of 3-isocyanatopropyltriethoxysilane are mixed, and then 0.035 part by weight of dibutyltin dilaurate is added, and the mixture is stirred at 42 °C for 4 h to obtain a mixed solution; 0.7 part by weight of the mixed solution and 2 parts by weight of zinc oxide nanoparticles are added to a mixed system composed of 200 parts by volume of anhydrous ethanol and water mixed in a volume ratio of 2:1, and ultrasonic treatment is carried out for 1 h under the conditions of an ultrasonic frequency of 40 KHz and an ultrasonic power of 50 W; the pH of the solution is adjusted to 10 with 1 mol / L NaOH aqueous solution, and the mixture is continuously stirred and reacted in an oil bath at 62 °C and 500 rpm for 12 h; the reaction product is washed 3 times with anhydrous ethanol and water respectively, filtered, and dried to obtain modified zinc oxide nanoparticles.

[0081] Comparative Example 4

[0082] A method for preparing a highly ductile PET film, comprising the following steps:

[0083] 70 parts by weight of PET resin was dried to obtain the dried PET resin; then the dried PET resin was mixed evenly with 4 parts by weight of polyethylene glycol, 12 parts by weight of filler, 2 parts by weight of triphenyl phosphate, 3 parts by weight of ethylene bisoleamide, and 1 part by weight of 2-hydroxypropiophenone, and then fed into a twin-screw extruder for melt extrusion to form a molten film. The screw speed was 200 rpm, the melting temperature was 280 °C, and then the molten film was cast on a cooling roller through a casting die head for cooling. The cooling temperature was 30 °C to form a cast sheet, and then it was subjected to transverse stretching, longitudinal stretching, and shaping to obtain a highly ductile PET film; the thickness of the PET film was 35 μm.

[0084] The filler was composed of talcum powder and modified attapulgite mixed in a mass ratio of 2:1.

[0085] The preparation method of the modified attapulgite was the same as that in Example 4.

[0086] Comparative Example 5

[0087] A preparation method of a highly ductile PET film, comprising the following steps:

[0088] 70 parts by weight of PET resin was dried to obtain the dried PET resin; then the dried PET resin was mixed evenly with 4 parts by weight of polyethylene glycol, 2 parts by weight of triphenyl phosphate, 1.5 parts by weight of phosphorylated chitosan / modified zinc oxide nanoparticle composite, 3 parts by weight of ethylene bisoleamide, and 1 part by weight of 2-hydroxypropiophenone, and then fed into a twin-screw extruder for melt extrusion to form a molten film. The screw speed was 200 rpm, the melting temperature was 280 °C, and then the molten film was cast on a cooling roller through a casting die head for cooling. The cooling temperature was 30 °C to form a cast sheet, and then it was subjected to transverse stretching, longitudinal stretching, and shaping to obtain a highly ductile PET film; the thickness of the PET film was 35 μm.

[0089] The preparation method of the phosphorylated chitosan / modified zinc oxide nanoparticle composite was the same as that in Example 1.

[0090] Test Example 1

[0091] The PET films prepared in Examples 1-5 and Comparative Examples 1-5 of the present invention were taken as film samples respectively for performance testing:

[0092] According to the standard of "GB / T 1040.1-2018 Plastics - Determination of tensile properties - Part 1: General principles", the tensile properties of the PET film samples were tested using a double-column bench universal testing machine. The film samples to be tested were cut into dumbbell-shaped specimens (the parallel part had a length of 12 mm and a width of 2 mm); the test conditions were: tensile at room temperature, the tensile rate was 10 mm / min, and each group of samples was tested 5 times and the average value was taken;

[0093] According to the standard of "QB / T 1130-1991 Test Method for Right-angle Tear Properties of Plastics", a universal tensile testing machine (AGS-X, Shimadzu, Japan) was used to test the tear strength of PET film samples; the test conditions were: tearing at room temperature, the tearing speed was 200 mm / min, and each group of samples was tested 5 times and the average value was taken;

[0094] The specific data of the test results are shown in Table 1:

[0095] Table 1

[0096]

[0097]

[0098] It can be seen from Table 1 that by comparing Examples 1-5 and Comparative Examples 1-5, it is found that compared with Comparative Example 5 without adding fillers, the elongation at break and tear strength of Examples 1-5 and Comparative Examples 1-4 with added fillers are significantly higher; by comparing Examples 1-5 and Comparative Examples 1-3, it is found that the elongation at break and tear strength of Example 5 and Comparative Examples 2-3 that choose to mix talc and modified attapulgite as fillers are higher than those of Example 1 that chooses talc as a filler, Examples 2-4 that choose modified attapulgite as a filler, and Comparative Example 1 that chooses to mix talc and attapulgite as fillers, indicating that the synergistic use of talc and modified attapulgite is more conducive to improving the ductility of PET film; the reason may be that talc is a layered silicate mineral with good chemical stability and mechanical properties, and its flaky structure can form a physical barrier in the PET matrix, which helps to disperse stress and thus improve the mechanical properties of the film; after acid activation and organic modification, modified attapulgite has rich active sites on its surface, which can better combine with the PET matrix, and the fibrous structure of modified attapulgite can enhance the toughness and ductility of the PET matrix, and improve the tensile resistance of the film through physical entanglement and chemical bonding. When talc and modified attapulgite are used synergistically, the flaky structure of talc and the fibrous structure of modified attapulgite form a composite reinforcement network in the PET matrix. This network structure can effectively disperse stress and prevent stress concentration, thereby increasing the elongation at break and tear strength of the film, and the active sites of modified attapulgite can form a stronger interfacial bond with the PET matrix, further enhancing the mechanical properties of the film.

[0099] Comparing Example 5 with Comparative Examples 2-4, it was found that, compared with Comparative Examples 2-3 with phosphorylated chitosan or modified zinc oxide nanoparticles added and Comparative Example 4 without the addition of phosphorylated chitosan / modified zinc oxide nanoparticle composite, the elongation at break and tear strength of Example 5 with the addition of phosphorylated chitosan / modified zinc oxide nanoparticle composite were higher, showing more excellent ductility. The reason may be that the flexible chain structure of phosphorylated chitosan and the high-strength support points of modified zinc oxide nanoparticles act together to form a composite reinforcement network, and the phosphate ester groups on phosphorylated chitosan in the phosphorylated chitosan / modified zinc oxide nanoparticle composite and the siloxy groups on the surface of modified zinc oxide nanoparticles can form hydrogen bonds or chemical bonds with the ester groups in the PET matrix, enhancing the interfacial bonding strength, effectively transmitting stress, and reducing stress concentration points, thus being beneficial to improving the mechanical properties of the film and its ductility.

[0100] Comparing Examples 2-4, it was found that, compared with Examples 2-3 where leucine or glutamic acid was selected as the modifier to prepare modified attapulgite, the elongation at break and tear strength of Example 4 where lysine was selected as the modifier to prepare modified attapulgite were higher. The reason may be that compared with leucine and glutamic acid, the two amino groups of lysine endow it with higher reactivity, enabling it to form more chemical bonds with the hydroxyl groups on the surface of attapulgite, and its molecular chain is longer, enabling it to better combine with the fibrous structure of attapulgite to form more stable physical entanglements. The multi-amino characteristics and long-chain structure of lysine enable it to form stronger chemical bonds and physical entanglements with the surface of attapulgite, optimize the microstructure, and enhance the interfacial bonding strength, thereby significantly improving the mechanical properties of the film. In contrast, the short-chain structure and lower reactivity of leucine and glutamic acid limit their modification effects.

[0101] Test Example 2

[0102] The PET films prepared in Examples 1-5 and Comparative Examples 1-5 of the present invention were respectively taken as test samples for limiting oxygen index test and antibacterial property test:

[0103] Referring to the standard of "GB / T 2406.2-2009 Plastics - Determination of burning behavior by the oxygen index method - Part 2: Room temperature test", an oxygen index tester (JF-3, Nanjing Jiangning Analytical Instrument Co., Ltd.) was used to test the limiting oxygen index of the PET film samples; each group of samples was tested 3 times and the average value was taken;

[0104] The antibacterial property test was carried out referring to the test method provided in the standard of "GB / T 31402-2015 Plastics - Test method for antibacterial properties of plastic surfaces"; experimental bacteria: Escherichia coli (commercially available, ATCC 8739), Staphylococcus aureus (commercially available, ATCC 6538P);

[0105] The specific data of the test results are shown in Table 2 as follows:

[0106] Table 2

[0107]

[0108] As can be seen from Table 2, by comparing Examples 1-5 with Comparative Examples 1-5, it is found that the limiting oxygen index of Examples 1-5, Comparative Examples 1-2 and Comparative Example 5 is significantly higher than that of Comparative Examples 3-4. Among them, Example 5 has the highest limiting oxygen index and excellent flame retardancy. The reason may be that the phosphorylated chitosan / modified zinc oxide nanoparticle composite introduced forms a composite flame retardant system in the PET matrix. The flexible chain structure of phosphorylated chitosan and the high-strength support points of modified zinc oxide nanoparticles work together to more effectively prevent the transfer of heat and oxygen. At the same time, the phosphoric acid generated by phosphorylated chitosan during combustion and the silica generated by modified zinc oxide nanoparticles cooperate with each other to form a more stable protective carbon layer, significantly improving the flame retardancy of the film. In addition, talc powder and modified attapulgite are added as fillers and used in synergy with it. Talc powder itself has a certain flame retardant effect, and its main component is magnesium silicate, which is a natural inorganic flame retardant. The organic modifier (such as lysine) in modified attapulgite may decompose at high temperatures to produce some gases or solid residues with flame retardant effects, further enhancing the flame retardant effect.

[0109] As can be seen from Table 2, by comparing Examples 1-5 with Comparative Examples 1-5, it is found that the antibacterial rates of Examples 1-5, Comparative Examples 1-3 and Comparative Example 5 are significantly higher than that of Comparative Example 4; by comparing Examples 1-5, Comparative Examples 1-3 and Comparative Example 5, it is found that the antibacterial rates of Examples 1-5 and Comparative Example 1 are higher than those of Comparative Examples 2-3 and Comparative Example 5, and Example 5 is the highest. The reason may be that the phosphorylated chitosan / modified zinc oxide nanoparticle composite introduced forms a composite antibacterial system in the PET matrix. The flexible chain structure of phosphorylated chitosan and the high-strength support points of modified zinc oxide nanoparticles work together to more effectively adsorb and inhibit bacteria. At the same time, phosphorylated chitosan adsorbs bacteria through physical entanglement, while modified zinc oxide nanoparticles further inhibit the growth of bacteria by releasing zinc ions and physical adsorption. The two work together to significantly improve the antibacterial performance of the film. In addition, talc powder and modified attapulgite are added as fillers and used in synergy with it. Talc powder itself has a certain antibacterial property, and the magnesium silicate component on its surface can adsorb bacteria, thereby inhibiting the growth and reproduction of bacteria. The amino group in modified attapulgite has an electrostatic interaction with the phosphate group in phosphorylated chitosan, further enhancing the stability of the composite and further enhancing the antibacterial effect.

Claims

1. A highly ductile PET film, characterized in that, The thin film comprises raw materials in the following parts by weight: 60 - 80 parts of PET resin, 3 - 5 parts of polyethylene glycol, 5 - 15 parts of filler, 1 - 3 parts of stabilizer, 1 - 2 parts of phosphorylated chitosan / modified zinc oxide nanoparticle composite, 0.5 - 5 parts of dispersant, 0.5 - 2 parts of antioxidant; The filler is selected from at least one of talcum powder and modified attapulgite; The phosphorylated chitosan / modified zinc oxide nanoparticle composite is obtained by surface - modifying zinc oxide nanoparticles with a silane coupling agent, phosphorylating and grafting chitosan with orthophosphoric acid, and finally compounding phosphorylated chitosan and modified zinc oxide in an acidic solution through ultrasonic assistance.

2. The highly ductile PET film according to claim 1, wherein: The stabilizer is at least one of calcium stearate, triphenyl phosphate, and trimethyl phosphate; 3. The highly ductile PET film according to claim 1, wherein: The dispersant is selected from at least one of polyethylene wax, paraffin wax, and ethylene bisoleamide; 4. The high-ductility PET film according to claim 1, wherein: The antioxidant is selected from at least one of tea polyphenols, tocopherols, 2 - hydroxyacetophenone, butylated hydroxyanisole, dibutylhydroxytoluene, and tert - butylhydroquinone; 5. The highly ductile PET film according to claim 1, characterized in that, The preparation method of the phosphorylated chitosan / modified zinc oxide nanoparticle composite comprises the following steps, by weight: S1. Mix 1.8 - 2.2 parts of ethyl acetate and 4.5 - 4.7 parts of 3 - isocyanatopropyltriethoxysilane, then add 0.03 - 0.04 parts of dibutyltin dilaurate, and mix and stir at 40 - 45 °C for 3 - 5 h to obtain a mixed solution; Add 0.65 - 0.75 parts of the mixed solution and 1.8 - 2.2 parts of zinc oxide nanoparticles into a mixed system composed of 195 - 205 parts of a mixture of absolute ethanol and water with a volume ratio of 2 - 2.2:1, and perform ultrasonic treatment for 0.5 - 1 h; Adjust the pH of the solution to 9.5 - 10.5, and continue to mix and stir and react at 60 - 65 °C and 400 - 600 rpm for 10 - 15 h; Filter, wash, and dry to obtain modified zinc oxide nanoparticles; S2. Add 8 - 12 parts of chitosan, 18 - 22 parts of orthophosphoric acid, and 90 - 110 parts of urea into 200 parts of N,N - dimethylformamide, and mix and stir at 145 - 155 °C for 0.5 - 2 h under nitrogen gas protection; After cooling, filter, wash, and dry to obtain phosphorylated chitosan; S3. Add 1.8 - 2.1 parts of phosphorylated chitosan into 95 - 105 parts of a 0.2 - 0.5 mol / L acetic acid solution, mix and stir for 8 - 12 h to obtain a mixed solution; Then add 0.1 - 0.5 parts of modified zinc oxide nanoparticles, and perform ultrasonic treatment for 20 - 40 min; Centrifuge to collect the precipitate, wash, and dry to obtain the phosphorylated chitosan / modified zinc oxide nanoparticle composite.

6. The high-ductility PET film according to claim 1, wherein The preparation method of the modified attapulgite comprises the following steps, by weight: Add 18 - 22 parts of attapulgite into 190 - 210 parts of 1 - 2 mol / L hydrochloric acid aqueous solution and mix evenly. After ultrasonic treatment for 20 - 40 min, mix and stir at 75 - 85 °C for 0.5 - 2 h; collect the precipitate after centrifugation, wash and dry to obtain acid-activated attapulgite; add 1.8 - 2.2 parts of the above acid-activated attapulgite and 0.3 - 0.6 part of modifier into 45 - 55 parts of water and mix. Then add 0.05 - 0.1 part by weight of p-toluenesulfonic acid as a catalyst, ultrasonic treat for 20 - 30 min, and then mix and stir at 80 - 90 °C for 3 - 5 h; neutralize the reaction system with 0.5 - 1 mol / L NaOH aqueous solution to remove the catalyst, then collect the precipitate after centrifugation and dry to obtain modified attapulgite.

7. The highly ductile PET film according to claim 6, wherein: The modifier is selected from at least one of lysine, glutamic acid, and leucine.

8. The preparation method of the highly ductile PET film according to any one of claims 1-7, characterized in that, It includes the following steps: Dry the PET resin to obtain the dried PET resin; then evenly mix the dried PET resin with polyethylene glycol, filler, stabilizer, phosphorylated chitosan / modified zinc oxide nanoparticle composite, dispersant, and antioxidant, and feed it into a twin-screw extruder for melt extrusion to form a molten film. Then, cast the molten film onto a cooling roller through a casting die head for cooling to form a cast sheet, and finally obtain a high-ductility PET film through transverse stretching, longitudinal stretching, and shaping.

9. The method for preparing a highly ductile PET film according to claim 8, characterized in that, The thickness of the PET film is 30 - 50 μm.

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