Antistatic PET dust-free film and preparation method thereof

Abstract

The invention discloses an antistatic PET dust-free film and a preparation method thereof, and relates to the technical field of high polymer materials. When the antistatic PET dust-free film is prepared, firstly, 6-bromohexanoic acid reacts with 4-imidazole-1-butyric acid, and then is subjected to ion exchange with potassium hexafluorophosphate to prepare diacid imidazole hexafluorophosphate ionic liquid; the preparation method comprises the following steps: enabling montmorillonite to react with tetraethoxysilane, 3-aminopropyltriethoxysilane and dodecyl triethoxysilane, so as to obtain modified montmorillonite; carrying out copolycondensation on terephthalic acid, the diacid imidazole hexafluorophosphate ionic liquid, ethylene glycol and the modified montmorillonite to prepare a modified polyester master batch; and carrying out melt blending on the modified polyester master batch and a chain extender, and carrying out blow molding to obtain the antistatic PET dust-free film. The prepared antistatic PET dust-free film has the advantages of being antistatic, flame-retardant, super-hydrophobic and low in dust adhesion rate.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to an antistatic PET dust-free film and its preparation method. Background Technology

[0002] Polyethylene terephthalate (PET) possesses excellent mechanical properties and chemical stability. It is produced in large quantities and is inexpensive, making it widely used in textile fibers, films, bottle containers, and in the automotive and electronics industries. PET has a regular molecular structure and is prone to crystallization, but its moisture absorption rate is only 0.4% under standard conditions, and its surface resistivity is as high as 10⁻⁶. 14 Ω, easily generates static electricity. Static materials not only attract charged particles from the environment, causing product contamination and reduced work efficiency, but also interfere with the operation of electronic equipment due to electrostatic discharge, and may even cause safety accidents.

[0003] Meanwhile, in optical device manufacturing workshops with high cleanliness requirements, the surface of PET film can adsorb dust from the air due to physical adsorption, hydrogen bonding, electrostatic adsorption, etc., leading to a decrease in cleanliness and limiting its application in high-cleanliness workshops. Therefore, it is necessary to improve the self-cleaning performance of the film to mitigate this issue. Summary of the Invention

[0004] The purpose of this invention is to provide an antistatic PET dust-free film and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: An antistatic PET dust-free film is prepared by melt-blending modified polyester masterbatch with chain extender and then blow molding it into a film. The modified polyester masterbatch is prepared by copolymerization of terephthalic acid with imidazole hexafluorophosphate ionic liquid, ethylene glycol, and modified montmorillonite. The diacid imidazole hexafluorophosphate ionic liquid is prepared by ion exchange of diacid imidazole bromide ionic liquid with potassium hexafluorophosphate. The diacid imidazole bromide ionic liquid is prepared by reacting 6-bromohexanoic acid with 4-imidazol-1-ylbutyric acid. The modified montmorillonite is prepared by reacting montmorillonite with tetraethyl orthosilicate, 3-aminopropyltriethoxysilane, and dodecyltriethoxysilane.

[0006] As an optimization, the chain extender contains epoxy groups.

[0007] A method for preparing an antistatic PET dust-free film includes the following preparation steps: (1) By mass fraction, under an argon atmosphere, 1.8~2.4 parts of 6-bromohexanoic acid, 1.19~1.58 parts of 4-imidazolium-1-ylbutyric acid and 8~12 parts of acetonitrile are mixed evenly, and the mixture is stirred and refluxed at 70~80℃ and 300~400r / min for 72~80h. The acetonitrile is removed by rotary evaporation, and the mixture is purified by extraction and washing with methanol and anhydrous diethyl ether. The mixture is then vacuum dried at 70~80℃ for 40~48h to obtain the diacid imidazolium bromide ionic liquid. (2) By mass fraction, under an argon atmosphere, 2-3 parts of diacid imidazole bromide ionic liquid, 4-5 parts of potassium hexafluorophosphate, and 20-25 parts of acetonitrile are mixed evenly and stirred and refluxed at 70-80℃ and 300-400r / min for 42-48h. The precipitate is removed by filtration, the acetonitrile is removed by rotary evaporation, the liquid is washed with pure water, and dried under vacuum at 70-80℃ for 20-24h to obtain diacid imidazole hexafluorophosphate ionic liquid. (3) Mix 3-4 parts of tetraethyl orthosilicate and 8-10 parts of ethanol-water mixture evenly by mass. Add 1.5-2 parts of 3-aminopropyltriethoxysilane, 0.6-0.8 parts of dodecyltriethoxysilane and 8-10 parts of ethanol-water mixture at room temperature and stirring at 200-300 r / min. Stir for 10-12 min. Then add 3-4 parts of montmorillonite and 16-20 parts of ethanol-water mixture. Adjust the pH to 5-6 with concentrated hydrochloric acid. Stir at 60-70℃ and 500-600 r / min for 3-4 h. Filter, wash with anhydrous ethanol, and vacuum dry at 50-60℃ for 12-16 h. Grind through a 100-mesh sieve to obtain modified montmorillonite. (4) By mass, under a nitrogen atmosphere, add 4-5 parts of terephthalic acid, 1.11-1.39 parts of imidazole hexafluorophosphate ionic liquid, 2.5-3.2 parts of ethylene glycol, and 0.01-0.013 parts of tetrabutyl titanate to the reactor and mix evenly. Seal the reactor and react at 230-250℃, with an internal pressure of 0.3-0.4MPa, a speed of 200-300r / min, and a steam tower top temperature of 120-150℃ until the esterification water content reaches 98% of the theoretical value. Depressurize and transfer to a polycondensation reactor. Add 0.5-0.6 parts of modified montmorillonite. At 250-270℃, evacuate to a vacuum degree of less than 50Pa and stir at 500-600r / min until the viscosity increases. Stop the reaction, purge with nitrogen to release the vacuum, pressurize and expel from the reactor, and granulate to obtain modified polyester masterbatch. (5) Mix 8-10 parts of modified polyester masterbatch and 0.03-0.04 parts of chain extender evenly in a high-speed mixer by mass, add to a twin-screw extruder, extrude and granulate at 250-260℃ and 25-35r / min, dry at 140-150℃ for 6-8h, transfer to a single-screw extrusion blown film machine to blown film, stretch and rewind to obtain antistatic PET dust-free film.

[0008] As an optimization, the reaction process of the diacid imidazole bromide ionic liquid in step (1) is as follows: .

[0009] As an optimization, the reaction process of the diacid imidazole hexafluorophosphate ionic liquid in step (2) is as follows: .

[0010] As an optimization, the ethanol-water mixture in step (3) is a mixture of ethanol and pure water in a volume ratio of 3:2.

[0011] As an optimization, the montmorillonite in step (3) is pretreated. The pretreatment method is as follows: by mass, 1-2 parts of montmorillonite are dispersed in 70-80 parts of pure water, ultrasonicated at room temperature for 30-40 minutes, stirred at 800-1000 r / min for 48-52 hours, filtered, and vacuum dried at 70-80℃ for 16-20 hours.

[0012] As an optimization, the montmorillonite in step (3) is sodium-based montmorillonite.

[0013] As an optimization, the mass percentage concentration of the concentrated hydrochloric acid in step (3) is 36%~38%.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are: In preparing an antistatic PET cleanroom film, the present invention first reacts 6-bromohexanoic acid with 4-imidazolium-1-ylbutyric acid to obtain a diacid imidazolium bromide ionic liquid; then, the diacid imidazolium bromide ionic liquid is ion-exchanged with potassium hexafluorophosphate to obtain a diacid imidazolium hexafluorophosphate ionic liquid; modified montmorillonite is prepared by reacting montmorillonite with tetraethyl orthosilicate, 3-aminopropyltriethoxysilane, and dodecyltriethoxysilane; a modified polyester masterbatch is prepared by co-condensation of terephthalic acid with the diacid imidazolium hexafluorophosphate ionic liquid, ethylene glycol, and modified montmorillonite; and finally, the modified polyester masterbatch is melt-blended with a chain extender and blow-molded into a film to obtain the antistatic PET cleanroom film.

[0015] First, 6-bromohexanoic acid is reacted with 4-imidazolium-1-ylbutyric acid and then ion-exchanged with potassium hexafluorophosphate to obtain diacid imidazolium hexafluorophosphate ionic liquid, which contains dicarboxyl groups and can participate in the co-condensation of PET polyester. This ionic liquid is used to introduce the polyester chain segment, thereby introducing a conductive network into the polyester chain segment and improving its antistatic properties. Furthermore, bromine salt is converted to hexafluorophosphate through ion exchange. Compared with the hydrophilicity of bromine salt, hexafluorophosphate has the opposite properties. Due to the presence of low surface energy fluorine, it exhibits certain hydrophobic properties. At the same time, flame retardant elements phosphorus, nitrogen, and fluorine are introduced, which can further improve the flame retardant properties of the film.

[0016] Secondly, modified montmorillonite was prepared by reacting montmorillonite with tetraethyl orthosilicate, 3-aminopropyltriethoxysilane, and dodecyltriethoxysilane. First, tetraethyl orthosilicate was grown in situ on the surface of montmorillonite, introducing nano-silica onto the montmorillonite. This growth step improved the surface roughness of the montmorillonite. Then, 3-aminopropyltriethoxysilane and dodecyltriethoxysilane were introduced onto the surface of montmorillonite in the subsequent reaction via silanol hydrolysis and condensation. This introduction of reactive amino groups and hydrophobic long carbon chains not only introduced the reactive amino groups but also effectively completed the structural modification of montmorillonite. Intercalation modification causes the montmorillonite sheets to curl, forming a rough micro / nano structure together with the surface-grown nano-silica. This further improves its hydrophobic properties, allowing it to provide a superhydrophobic surface after being introduced into the film. The superhydrophobic structure has good self-cleaning properties, and its low surface energy prevents the adhesion of most substances, avoiding the decrease in cleanliness caused by dust adhesion. At the same time, the amino groups introduced on it can undergo transesterification with the polyester backbone during polycondensation, thereby fixing it in the film through covalent bonds and preventing failure caused by particle migration.

[0017] Finally, a modified polyester masterbatch was prepared by co-condensation of terephthalic acid with imidazole hexafluorophosphate ionic liquid, ethylene glycol, and modified montmorillonite. The modified polyester masterbatch was then melt-blended with a chain extender and blow-molded to obtain an antistatic PET cleanroom film. Both the imidazole hexafluorophosphate ionic liquid and the modified montmorillonite entered the polyester backbone through the polycondensation reaction, thereby introducing flame-retardant, antistatic, and superhydrophobic functional groups into the polyester. After obtaining the masterbatch, it was melt-blended with a chain extender containing epoxy groups. During the melt-blending process, the epoxy groups on the chain extender reacted with the terminal hydroxyl groups on the modified polyester masterbatch, thereby extending the polyester chain segments and improving its toughness and strength, making it applicable to the blow-molding process, thus obtaining an antistatic PET cleanroom film with flame retardant, antistatic, and superhydrophobic properties. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] The raw material information used in all the following examples and comparative examples is as follows: Chain extender: Brand is BASF (Germany), model is ADR-4368; Montmorillonite: Sodium-based montmorillonite, model PGV, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd. After pretreatment, the pretreatment method is to disperse 1.5 parts of montmorillonite in 75 parts of pure water by mass, sonicate at room temperature for 35 min, stir at 900 r / min for 50 h, filter, and vacuum dry at 75℃ for 18 h. Concentrated hydrochloric acid: A hydrochloric acid aqueous solution with a mass percentage concentration of 36%.

[0020] Example 1: A method for preparing an antistatic PET cleanroom film, the method comprising the following steps: (1) By mass fraction, 1.8 parts of 6-bromohexanoic acid, 1.19 parts of 4-imidazolium-1-ylbutyric acid and 8 parts of acetonitrile were mixed evenly under an argon atmosphere, stirred and refluxed at 70°C and 300 r / min for 80 h, acetonitrile was removed by rotary evaporation, and purified by extraction and washing with methanol and anhydrous diethyl ether. The mixture was then vacuum dried at 70°C for 48 h to obtain the diacid imidazolium bromide ionic liquid. (2) By mass fraction, under an argon atmosphere, 2 parts of diacid imidazole bromide ionic liquid, 4 parts of potassium hexafluorophosphate and 20 parts of acetonitrile were mixed evenly and stirred and refluxed at 70°C and 300 r / min for 48 h. The precipitate was removed by filtration, the acetonitrile was removed by rotary evaporation, and the mixture was washed with pure water and dried under vacuum at 70°C for 24 h to obtain diacid imidazole hexafluorophosphate ionic liquid. (3) According to the mass fraction, 3 parts of tetraethyl orthosilicate and 8 parts of ethanol-water mixture are mixed evenly. Under the stirring condition of 200r / min at room temperature, 1.5 parts of 3-aminopropyltriethoxysilane, 0.6 parts of dodecyltriethoxysilane and 8 parts of ethanol-water mixture are added and stirred for 10min. Then, 3 parts of montmorillonite and 16 parts of ethanol-water mixture are added. The pH is adjusted to 5 with concentrated hydrochloric acid. The mixture is stirred at 500r / min at 60℃ for 4h. After filtration, it is washed with anhydrous ethanol and dried under vacuum at 50℃ for 16h. The modified montmorillonite is obtained by grinding through a 100-mesh sieve. (4) By mass, under a nitrogen atmosphere, 4 parts of terephthalic acid, 1.11 parts of imidazole hexafluorophosphate ionic liquid, 2.5 parts of ethylene glycol, and 0.01 parts of tetrabutyl titanate were added to the reactor and mixed evenly. The reactor was sealed and the reaction was carried out at 230°C, with an internal pressure of 0.3 MPa, a speed of 200 r / min, and a steam tower top temperature of 120°C until the esterification water content reached 98% of the theoretical value. The pressure was released and the mixture was transferred to a polycondensation reactor. 0.5 parts of modified montmorillonite were added. The reactor was evacuated at 250°C until the vacuum degree was less than 50 Pa. The mixture was stirred at 500 r / min until the viscosity increased. The reaction was stopped, nitrogen was introduced to release the vacuum, and the mixture was pressed out of the reactor and pelletized to obtain the modified polyester masterbatch. (5) By mass, 8 parts of modified polyester masterbatch and 0.03 parts of chain extender are mixed evenly in a high-speed mixer, added to a twin-screw extruder, extruded and granulated at 250°C and 25r / min, dried at 140°C for 8 hours, transferred to a single-screw extrusion blown film machine for blown film forming, and then stretched and wound to obtain an antistatic PET dust-free film.

[0021] Example 2: A method for preparing an antistatic PET cleanroom film, the method comprising the following steps: (1) By mass fraction, 2.1 parts of 6-bromohexanoic acid, 1.38 parts of 4-imidazolium-1-ylbutyric acid and 10 parts of acetonitrile were mixed evenly under an argon atmosphere, stirred and refluxed at 75°C and 350 r / min for 76 h, acetonitrile was removed by rotary evaporation, and purified by extraction and washing with methanol and anhydrous diethyl ether. The mixture was then vacuum dried at 75°C for 44 h to obtain the diacid imidazolium bromide ionic liquid. (2) By mass fraction, under an argon atmosphere, 2.5 parts of diacid imidazole bromide ionic liquid, 4.5 parts of potassium hexafluorophosphate and 22.5 parts of acetonitrile were mixed evenly and stirred and refluxed at 75°C and 350 r / min for 45 h. The precipitate was removed by filtration, the acetonitrile was removed by rotary evaporation, the mixture was washed with pure water and dried under vacuum at 75°C for 22 h to obtain diacid imidazole hexafluorophosphate ionic liquid. (3) According to the mass fraction, 3.5 parts of tetraethyl orthosilicate and 9 parts of ethanol-water mixture were mixed evenly. Under the stirring condition of 250 r / min at room temperature, 1.8 parts of 3-aminopropyltriethoxysilane, 0.7 parts of dodecyltriethoxysilane and 9 parts of ethanol-water mixture were added and stirred for 11 min. Then, 3.5 parts of montmorillonite and 18 parts of ethanol-water mixture were added. The pH was adjusted to 5.5 with concentrated hydrochloric acid. The mixture was stirred at 550 r / min at 65℃ for 3.5 h. After filtration, it was washed with anhydrous ethanol and dried under vacuum at 55℃ for 14 h. The modified montmorillonite was obtained by grinding through a 100-mesh sieve. (4) By mass, under a nitrogen atmosphere, 4.5 parts of terephthalic acid, 1.25 parts of imidazole hexafluorophosphate ionic liquid, 2.8 parts of ethylene glycol, and 0.0116 parts of tetrabutyl titanate were added to the reactor and mixed evenly. The reactor was sealed and the reaction was carried out at 240°C, with an internal pressure of 0.35 MPa, a speed of 250 r / min, and a steam tower top temperature of 135°C until the esterification water content reached 98% of the theoretical value. The pressure was released and the mixture was transferred to a polycondensation reactor. 0.55 parts of modified montmorillonite were added. The reactor was evacuated to a vacuum degree of less than 50 Pa at 260°C and stirred at 550 r / min until the viscosity increased. The reaction was stopped, nitrogen was introduced to release the vacuum, and the mixture was pressed out of the reactor and pelletized to obtain the modified polyester masterbatch. (5) According to the mass fraction, 9 parts of modified polyester masterbatch and 0.035 parts of chain extender are mixed evenly in a high-speed mixer, added to a twin-screw extruder, extruded and granulated at 255°C and 30 r / min, dried at 145°C for 7 h, transferred to a single-screw extrusion blown film machine for blown film forming, and obtained antistatic PET dust-free film after stretching and winding.

[0022] Example 3: A method for preparing an antistatic PET cleanroom film, the method comprising the following steps: (1) By mass fraction, under an argon atmosphere, 2.4 parts of 6-bromohexanoic acid, 1.58 parts of 4-imidazolium-1-ylbutyric acid and 12 parts of acetonitrile were mixed evenly and stirred and refluxed at 80°C and 400 r / min for 72 h. Acetonitrile was removed by rotary evaporation, and the mixture was purified by extraction and washing with methanol and anhydrous diethyl ether. The mixture was then dried under vacuum at 80°C for 40 h to obtain the diacid imidazolium bromide ionic liquid. (2) By mass fraction, under an argon atmosphere, 3 parts of diacid imidazole bromide ionic liquid, 5 parts of potassium hexafluorophosphate and 25 parts of acetonitrile were mixed evenly and stirred and refluxed at 80°C and 400 r / min for 42 h. The precipitate was removed by filtration, the acetonitrile was removed by rotary evaporation, and the mixture was washed with pure water and dried under vacuum at 80°C for 20 h to obtain diacid imidazole hexafluorophosphate ionic liquid. (3) By mass fraction, 4 parts of tetraethyl orthosilicate and 10 parts of ethanol-water mixture were mixed evenly. At room temperature and under stirring at 300 r / min, 2 parts of 3-aminopropyltriethoxysilane, 0.8 parts of dodecyltriethoxysilane and 10 parts of ethanol-water mixture were added and stirred for 12 min. Then, 4 parts of montmorillonite and 20 parts of ethanol-water mixture were added. The pH was adjusted to 6 with concentrated hydrochloric acid. The mixture was stirred at 70℃ and 600 r / min for 3 h. The mixture was filtered, washed with anhydrous ethanol, dried under vacuum at 60℃ for 12 h, and ground through a 100-mesh sieve to obtain modified montmorillonite. (4) By mass, under a nitrogen atmosphere, 5 parts of terephthalic acid, 1.39 parts of imidazole hexafluorophosphate ionic liquid, 3.2 parts of ethylene glycol, and 0.013 parts of tetrabutyl titanate were added to the reactor and mixed evenly. The reactor was sealed and the reaction was carried out at 250°C, with an internal pressure of 0.4 MPa, a speed of 300 r / min, and a steam tower top temperature of 150°C until the esterification water content reached 98% of the theoretical value. The pressure was released and the mixture was transferred to a polycondensation reactor. 0.6 parts of modified montmorillonite were added. The reactor was evacuated at 270°C until the vacuum degree was less than 50 Pa. The mixture was stirred at 600 r / min until the viscosity increased. The reaction was stopped, nitrogen was introduced to release the vacuum, and the mixture was pressed out of the reactor and pelletized to obtain the modified polyester masterbatch. (5) By mass, 10 parts of modified polyester masterbatch and 0.04 parts of chain extender are mixed evenly in a high-speed mixer, added to a twin-screw extruder, extruded and granulated at 260°C and 35r / min, dried at 150°C for 6 hours, transferred to a single-screw extrusion blown film machine for blown film forming, and then stretched and wound to obtain an antistatic PET dust-free film.

[0023] Comparative Example 1: The preparation method of the antistatic PET dust-free film in Comparative Example 1 differs from that in Example 2 in that step (2) is omitted, and step (4) is modified as follows: In a nitrogen atmosphere, 4.5 parts by mass of terephthalic acid, 1.25 parts by mass of imidazole bromide ionic liquid, 2.8 parts by mass of ethylene glycol, and 0.0116 parts by mass of tetrabutyl titanate are added to a reaction vessel and mixed evenly. The reaction vessel is then sealed, and the reaction is carried out at 240°C, with an internal pressure of 0.35 MPa, a speed of 250 r / min, and a steam tower top temperature of 135°C, until the esterification water content reaches 98% of the theoretical value. The pressure is then released and the mixture is transferred to a polycondensation vessel. 0.55 parts by mass of modified montmorillonite are added, and the reaction is carried out at 260°C with a vacuum level less than 50 Pa. The mixture is stirred at 550 r / min until the viscosity increases, and the reaction is stopped. Nitrogen gas is introduced to release the vacuum, and the mixture is pressurized and extruded from the reaction vessel. The pellets are then obtained to obtain the modified polyester masterbatch. The remaining steps are the same as in Example 2.

[0024] Comparative Example 2: The preparation method of the antistatic PET dust-free film in Comparative Example 2 differs from that in Example 2 in that steps (1) and (2) are omitted, and step (4) is modified as follows: 5 parts by mass of terephthalic acid, 2.8 parts of ethylene glycol, and 0.0116 parts of tetrabutyl titanate are added to a reaction vessel under a nitrogen atmosphere and mixed evenly. The reaction vessel is sealed, and the reaction is carried out at 240°C, with an internal pressure of 0.35 MPa, a speed of 250 r / min, and a steam tower top temperature of 135°C, until the esterification water content reaches 98% of the theoretical value. The pressure is then released and the mixture is transferred to a polycondensation vessel. 0.55 parts of modified montmorillonite are added, and the reaction is carried out at 260°C with a vacuum level less than 50 Pa. The mixture is stirred at 550 r / min until the viscosity increases, and the reaction is stopped. Nitrogen gas is introduced to release the vacuum, and the mixture is pressurized and extruded from the reaction vessel. The pellets are then obtained to obtain the modified polyester masterbatch. The remaining steps are the same as in Example 2.

[0025] Comparative Example 3: The difference between the preparation method of the antistatic PET dust-free film in Comparative Example 3 and that in Example 2 lies in step (3). Step (3) is modified as follows: 3.5 parts by mass of tetraethyl orthosilicate and 9 parts by mass of ethanol-water mixture are mixed evenly. Under stirring conditions of 250 r / min at room temperature, 1.8 parts by mass of 3-aminopropyltriethoxysilane and 9 parts by mass of ethanol-water mixture are added and stirred for 11 min. Then, 3.5 parts by mass of montmorillonite and 18 parts by mass of ethanol-water mixture are added. The pH is adjusted to 5.5 with concentrated hydrochloric acid. The mixture is stirred at 65°C and 550 r / min for 3.5 h. After filtration, the mixture is washed with anhydrous ethanol and dried under vacuum at 55°C for 14 h. The modified montmorillonite is then obtained by grinding through a 100-mesh sieve. The remaining steps are the same as in Example 2.

[0026] Comparative Example 4: The difference between the preparation method of the antistatic PET dust-free film in Comparative Example 4 and Example 2 lies in step (3). Step (3) is modified as follows: 3.5 parts by mass of tetraethyl orthosilicate and 9 parts by mass of ethanol-water mixture are mixed evenly. Under stirring conditions of 250 r / min at room temperature, 0.7 parts by mass of dodecyltriethoxysilane and 9 parts by mass of ethanol-water mixture are added and stirred for 11 min. Then, 3.5 parts by mass of montmorillonite and 18 parts by mass of ethanol-water mixture are added. The pH is adjusted to 5.5 with concentrated hydrochloric acid. The mixture is stirred at 550 r / min at 65°C for 3.5 h. After filtration, the mixture is washed with anhydrous ethanol and dried under vacuum at 55°C for 14 h. The modified montmorillonite is then obtained by grinding through a 100-mesh sieve. The remaining steps are the same as in Example 2.

[0027] Comparative Example 5: The difference between the preparation method of the antistatic PET dust-free film of Comparative Example 5 and Example 2 lies in the difference in step (3). Step (3) is modified as follows: Take 9 parts by mass of the ethanol-water mixture, add 1.8 parts of 3-aminopropyltriethoxysilane, 0.7 parts of dodecyltriethoxysilane, and 9 parts of the ethanol-water mixture under stirring at 250 r / min at room temperature, stir for 11 min, then add 3.5 parts of montmorillonite and 18 parts of the ethanol-water mixture, adjust the pH to 5.5 with concentrated hydrochloric acid, stir at 550 r / min at 65℃ for 3.5 h, filter, wash with anhydrous ethanol, vacuum dry at 55℃ for 14 h, and grind through a 100-mesh sieve to obtain modified montmorillonite. The remaining steps are the same as in Example 2.

[0028] Comparative Example 6: The difference between the preparation method of the antistatic PET dust-free film of Comparative Example 6 and Example 2 lies in the difference in step (3). Step (3) is modified as follows: 3.5 parts by mass of tetraethyl orthosilicate and 9 parts by mass of pure water are mixed evenly. Under stirring conditions of 250 r / min at room temperature, 1.8 parts by mass of 3-aminopropyltriethoxysilane, 0.7 parts by mass of dodecyltriethoxysilane and 9 parts by mass of pure water are added and stirred for 11 min. Then, 3.5 parts by mass of montmorillonite and 18 parts by mass of pure water are added. The pH is adjusted to 5.5 with concentrated hydrochloric acid. The mixture is stirred at 550 r / min at 65°C for 3.5 h. After filtration, the mixture is washed with anhydrous ethanol and dried under vacuum at 55°C for 14 h. The modified montmorillonite is then obtained by grinding through a 100-mesh sieve. The remaining steps are the same as in Example 2.

[0029] Comparative Example 7: The preparation method of the antistatic PET dust-free film in Comparative Example 7 differs from that in Example 2 in that step (3) is omitted, and step (4) is modified as follows: In a nitrogen atmosphere, 4.5 parts by mass of terephthalic acid, 1.25 parts by mass of imidazole hexafluorophosphate ionic liquid, 2.8 parts by mass of ethylene glycol, and 0.0116 parts by mass of tetrabutyl titanate are added to a reaction vessel and mixed evenly. The reaction vessel is then sealed, and the reaction is carried out at 240°C, with an internal pressure of 0.35 MPa, a speed of 250 r / min, and a steam tower top temperature of 135°C, until the esterification water content reaches 98% of the theoretical value. The pressure is then released and the mixture is transferred to a polycondensation reactor. At 260°C, a vacuum is drawn until the vacuum degree is less than 50 Pa, and the mixture is stirred at 550 r / min until the viscosity increases. The reaction is then stopped, nitrogen is introduced to release the vacuum, and the mixture is pressurized and extruded from the reaction vessel. The pellets are then obtained to obtain the modified polyester masterbatch. The remaining steps are the same as in Example 2.

[0030] Test Example 1: Functional performance testing: The antistatic properties, superhydrophobicity, and dust adhesion of the prepared antistatic PET dust-free film were tested to evaluate its functionality. The specific test methods are as follows: Antistatic properties: The surface resistivity of the prepared antistatic PET dust-free film was tested according to GB / T 31838.3-2019 standard. The test was conducted using a ZC90G model high resistance insulation meter. The sample size was 100mm×100mm×0.5mm. The sample was pretreated for 96h at 23℃ and 50% relative humidity. The surface resistance was measured after applying 100V voltage and electrolyzing for 1min using the electrode device for measuring flat plate samples. The surface resistivity was calculated according to the formula in the standard. Each group of samples was tested in parallel 5 times, and the average value was recorded.

[0031] Superhydrophobicity: The contact angle between the antistatic PET cleanroom film and water was tested using a contact angle tester. The test method was to drop 5μL of water onto the surface of the antistatic PET cleanroom film at standard atmospheric pressure and 20℃. After the droplet remained for 5 seconds, the contact angle was measured and the data was recorded. Each group was tested in parallel 5 times, and the average value was recorded.

[0032] Dust adhesion: First, fix the antistatic PET cleanroom film onto a flat piece of cardboard and weigh it. Place approximately 1.02g of dust particles with a diameter of 0.1μm~5μm on the surface of the antistatic PET cleanroom film. Use a fan with a wind speed of 0.6m / s to blow air from a distance of 20cm from the antistatic PET cleanroom film to simulate a natural wind environment. After 30 minutes, weigh the cardboard piece with the antistatic PET cleanroom film fixed on it. Calculate the dust removal rate of the antistatic PET cleanroom film by the mass difference to test the dustproof effect and dust adhesion of the antistatic PET cleanroom film. Each group was tested in parallel 5 times, and the average value was recorded.

[0033] The results are shown in Table 1.

[0034] Table 1

[0035] A comparison of the experimental data of Examples 1-3 and Comparative Examples 1-7 in Table 1 reveals that the antistatic PET dust-free film prepared by the present invention has good antistatic properties, superhydrophobic properties, and low dust adhesion.

[0036] By comparing the data in the table, the data in Comparative Example 1 shows that ion exchange of diacid imidazole bromide ionic liquid yields hexafluorophosphate ions. Although hexafluorophosphate ions are slightly inferior to bromide ions in terms of antistatic enhancement, hexafluorophosphate ions contain low surface energy fluorine, which can synergistically improve hydrophobic properties and further reduce dust adhesion and improve dust removal rate.

[0037] By comparing the data in the table, the data in Comparative Example 2 shows that the addition of diacid imidazole hexafluorophosphate ionic liquid introduces a conductive network into the polyester chain segment, thereby effectively improving the antistatic performance and reducing the surface resistivity. The significant improvement in antistatic performance also effectively improves the dust removal rate and reduces dust adhesion. Furthermore, the fluorine element contained therein can synergistically improve the hydrophobic performance.

[0038] By comparing the data in the table, the data in Comparative Example 3 shows that the use of dodecyltriethoxysilane for modification of montmorillonite successfully intercalated the montmorillonite sheets, and intensified the curling of the montmorillonite sheets, which improved the roughness of the constructed micro-nano structure. In addition, the long carbon chain itself has good hydrophobic properties. Both of these factors together improved the hydrophobic properties, and the surface energy was further reduced by the improvement of hydrophobic properties, resulting in a decrease in the adhesion rate of dust.

[0039] By comparing the data in the table, the data in Comparative Example 4 shows that the use of 3-aminopropyltriethoxysilane to modify montmorillonite successfully intercalated the montmorillonite sheets, and intensified the curling of the montmorillonite sheets, which improved the roughness of the constructed micro-nano structure and enhanced the hydrophobic properties. The introduced amino group improved the compatibility of montmorillonite in polyester, allowing it to be fixed to the polyester chain segments through covalent bonds.

[0040] By comparing the data in the table, the data in Comparative Example 5 shows that nano-silica was successfully grown on the surface of montmorillonite sheets. The in-situ growth of nano-silica effectively improved the surface roughness of montmorillonite and synergistically constructed a hydrophobic micro-nano structure, improving hydrophobic properties. Furthermore, the improved hydrophobic properties further reduced the surface energy and decreased the adhesion rate of dust.

[0041] By comparing the data in the table, the data in Comparative Example 6 shows that using an ethanol-water mixture as a solvent for the modification reaction of montmorillonite yielded better results than reacting in an aqueous system. The ethanol-water mixture promoted the modification reaction of montmorillonite, further intensified the curling of montmorillonite sheets, increased the roughness of the constructed micro-nano structures, improved hydrophobic properties, and further reduced surface energy and dust adhesion rate through the improvement of hydrophobic properties.

[0042] By comparing the data in the table, the data in Comparative Example 7 shows that the addition of modified montmorillonite effectively improves the hydrophobic properties. The micro-nano structure it constructs provides excellent superhydrophobic properties, and through the improvement of hydrophobic properties, the surface energy is further reduced, and the adhesion rate of dust decreases.

[0043] Test Example 2: Flame retardant performance testing: The limiting oxygen index and UL 94 flammability rating of the prepared antistatic PET dust-free film were tested to evaluate its flame retardant effect. The specific test methods are as follows: Limiting oxygen index test: The limiting oxygen index of the antistatic PET dust-free films prepared in the examples and comparative examples was tested using an oxygen index instrument according to GB / T 2406.1-2008. The sample size was 150mm×10mm×3mm, and the average value of 5 samples in each group was recorded. Vertical combustion test: The test was conducted using a vertical-horizontal combustion tester according to ASTM D3801-2010. Five samples were tested in each group, and the average value was recorded.

[0044] The results are shown in Table 2.

[0045] Table 2

[0046] A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-7 in Table 2 reveals that the antistatic PET dust-free film prepared by this invention has good flame-retardant properties.

[0047] By comparing the data in the table, the data in Comparative Examples 1 and 2 show that the introduction of diacid imidazole hexafluorophosphate ionic liquid successfully improved the flame retardant performance. The hexafluorophosphate ions obtained by ion exchange contain phosphorus and fluorine flame retardant elements, which, together with the nitrogen element on the imidazole ring and the montmorillonite sheets, work synergistically to effectively improve the flame retardant performance.

[0048] The data comparison in the table shows that the addition of modified montmorillonite effectively and synergistically improves flame retardant performance through the physical barrier framework of montmorillonite, thereby increasing the limiting oxygen index and UL 94 flame retardant rating.

[0049] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. 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 PET dust-free film, characterized in that, The antistatic PET dust-free film is prepared by melt-blending modified polyester masterbatch with chain extender and then blow molding it into a film. The modified polyester masterbatch is prepared by copolymerization of terephthalic acid with imidazole hexafluorophosphate ionic liquid, ethylene glycol, and modified montmorillonite. The diacid imidazole hexafluorophosphate ionic liquid is prepared by ion exchange of diacid imidazole bromide ionic liquid with potassium hexafluorophosphate. The diacid imidazole bromide ionic liquid is prepared by reacting 6-bromohexanoic acid with 4-imidazol-1-ylbutyric acid. The modified montmorillonite is prepared by reacting montmorillonite with tetraethyl orthosilicate, 3-aminopropyltriethoxysilane, and dodecyltriethoxysilane.

2. The antistatic PET dust-free film according to claim 1, characterized in that, The chain extender contains epoxy groups.

3. A method for preparing an antistatic PET dust-free film, characterized in that, The preparation steps include the following: (1) Under an argon atmosphere, 6-bromohexanoic acid, 4-imidazolium-1-ylbutyric acid and acetonitrile were mixed evenly, stirred and refluxed, evaporated by rotary evaporation, extracted, washed and purified, and dried to obtain diacid imidazolium bromide ionic liquid. (2) Under an argon atmosphere, the diacid imidazole bromide ionic liquid, potassium hexafluorophosphate and acetonitrile were mixed evenly, stirred and refluxed, filtered, rotary evaporated, washed and dried to obtain the diacid imidazole hexafluorophosphate ionic liquid. (3) Mix tetraethyl orthosilicate and ethanol-water mixture evenly, add 3-aminopropyltriethoxysilane, dodecyltriethoxysilane and ethanol-water mixture under stirring at room temperature, stir, then add montmorillonite and ethanol-water mixture, adjust pH, stir reaction at 60~70℃, filter, wash, dry, grind and sieve to obtain modified montmorillonite. (4) Under a nitrogen atmosphere, terephthalic acid, imidazole hexafluorophosphate ionic liquid, ethylene glycol and tetrabutyl titanate are added to the reactor and mixed evenly. The reactor is sealed and the reaction is carried out until the amount of esterification water reaches 98% of the theoretical value. The pressure is released and the mixture is transferred to a polycondensation reactor. Modified montmorillonite is added, a vacuum is drawn, and the reaction is stirred until the viscosity increases. The reaction is stopped, the vacuum is released, and the mixture is pressed out of the reactor and pelletized to obtain modified polyester masterbatch. (5) By mass fraction, the modified polyester masterbatch and chain extender are mixed evenly in a high-speed mixer, added to a twin-screw extruder, extruded and granulated, dried, transferred to a single-screw extrusion blown film machine for blown film forming, stretched and wound to obtain an antistatic PET dust-free film.

4. The method for preparing an antistatic PET dust-free film according to claim 3, characterized in that, The diacid imidazole bromide ionic liquid in step (1) is prepared by mixing 1.8~2.4 parts of 6-bromohexanoic acid, 1.19~1.58 parts of 4-imidazolium-1-ylbutyric acid and 8~12 parts of acetonitrile by mass under an argon atmosphere, stirring and refluxing at 70~80℃ for 72~80h, removing acetonitrile by rotary evaporation, extracting and washing for purification, and vacuum drying at 70~80℃ for 40~48h.

5. The method for preparing an antistatic PET dust-free film according to claim 3, characterized in that, The diacid imidazole hexafluorophosphate ionic liquid described in step (2) is prepared by mixing 2-3 parts by mass of diacid imidazole bromide ionic liquid, 4-5 parts by mass of potassium hexafluorophosphate, and 20-25 parts by mass of acetonitrile under an argon atmosphere, stirring and refluxing at 70-80°C for 42-48 hours, filtering to remove the precipitate, rotary evaporating to remove the acetonitrile, washing, and vacuum drying at 70-80°C for 20-24 hours.

6. The method for preparing an antistatic PET dust-free film according to claim 3, characterized in that, The modified montmorillonite in step (3) is prepared by mixing 3-4 parts of tetraethyl orthosilicate and 8-10 parts of ethanol-water mixture evenly by mass, adding 1.5-2 parts of 3-aminopropyltriethoxysilane, 0.6-0.8 parts of dodecyltriethoxysilane and 8-10 parts of ethanol-water mixture under stirring at room temperature, stirring for 10-12 minutes, then adding 3-4 parts of montmorillonite and 16-20 parts of ethanol-water mixture, adjusting the pH to 5-6 with concentrated hydrochloric acid, stirring and reacting at 60-70℃ for 3-4 hours, filtering, washing, vacuum drying at 50-60℃ for 12-16 hours, and grinding and sieving.

7. The method for preparing an antistatic PET dust-free film according to claim 3, characterized in that, The ethanol-water mixture in step (3) is a mixture of ethanol and pure water in a volume ratio of 3:

2.

8. The method for preparing an antistatic PET dust-free film according to claim 3, characterized in that, The montmorillonite mentioned in step (3) has been pretreated. The pretreatment method is as follows: by mass, 1-2 parts of montmorillonite are dispersed in 70-80 parts of pure water, ultrasonicated at room temperature for 30-40 minutes, stirred at 800-1000 r / min for 48-52 hours, filtered, and vacuum dried at 70-80℃ for 16-20 hours.

9. The method for preparing an antistatic PET dust-free film according to claim 3, characterized in that, The modified polyester masterbatch in step (4) is prepared by mixing 4-5 parts of terephthalic acid, 1.11-1.39 parts of imidazole hexafluorophosphate ionic liquid, 2.5-3.2 parts of ethylene glycol, and 0.01-0.013 parts of tetrabutyl titanate in a reaction vessel under a nitrogen atmosphere. The reaction vessel is then sealed and the mixture is stirred at 230-250°C, with an internal pressure of 0.3-0.4 MPa and a steam tower top temperature of 120-150°C until the esterification water content reaches 98% of the theoretical value. The mixture is then depressurized and transferred to a polycondensation vessel. 0.5-0.6 parts of modified montmorillonite are added, and the mixture is stirred at 250-270°C until the vacuum degree is less than 50 Pa. The mixture is stirred until the viscosity increases, and the reaction is stopped. Nitrogen gas is introduced to release the vacuum, and the mixture is then pressurized and extruded from the reaction vessel and granulated to obtain the final product.

10. The method for preparing an antistatic PET dust-free film according to claim 3, characterized in that, The antistatic PET dust-free film described in step (5) is made by mixing 8-10 parts of modified polyester masterbatch and 0.03-0.04 parts of chain extender in a high-speed mixer by mass, adding the mixture to a twin-screw extruder, extruding and granulating at 250-260℃ and 25-35r / min, drying at 140-150℃ for 6-8 hours, transferring the mixture to a single-screw extrusion blown film machine for blown film forming, and stretching and winding to obtain the final product.

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