Antistatic coating liquid and antistatic film

Abstract

The invention relates to the technical field of high polymer material preparation, in particular to an antistatic coating liquid and an antistatic film, the antistatic coating liquid comprises the following raw materials by weight: 1.5-3 parts of an antistatic agent; 20 to 36 parts of water-based acrylic resin; 5-9 parts of a cross-linking agent; 0.5-2 parts of a wetting agent; 50 to 75 parts of water; wherein the antistatic agent is prepared by taking water, an MXene dispersion liquid and a conductive polymer as raw materials. According to the antistatic coating liquid provided by the invention, an antistatic coating can be introduced on the surface of a base film in an online coating manner, and an antistatic agent is prevented from being introduced into a base body of the base film, so that the antistatic performance of the polyester film can be improved on the premise that the mechanical property of the polyester film is not influenced.

Description

Technical Field

[0001] This invention relates to the field of polymer material preparation technology, and in particular to an antistatic coating liquid and an antistatic film. Background Technology

[0002] BOPET (biaxially oriented polyethylene terephthalate) film is a polymer material widely used in packaging, electronics, optics, and other fields. However, BOPET film has a relatively high surface resistivity, making it prone to static electricity accumulation during practical applications, which limits its application range to some extent. Therefore, improving the antistatic properties of BOPET film is currently a hot research topic.

[0003] Existing solutions primarily involve adding high-purity antistatic agents such as glyceryl stearate, oleamide, and ethylamine during the preparation of polyester film masterbatch to improve its antistatic properties. However, while these antistatic agents enhance antistatic performance, they also negatively impact the mechanical properties of the polyester film, thus limiting its applications. Summary of the Invention

[0004] To address the problem that existing polyester films struggle to balance antistatic and mechanical properties, this invention provides an antistatic coating liquid. This antistatic coating liquid introduces an antistatic coating with good adhesion to the PET surface, improving the antistatic properties of the film without sacrificing its mechanical properties, thus solving the problem of existing polyester films struggling to balance antistatic and mechanical properties.

[0005] The technical solution adopted by this invention to solve its technical problem is: An antistatic coating liquid, wherein the raw materials of the antistatic coating liquid, by weight, include the following components: 1.5-3 parts antistatic agent; 20-36 parts of water-based acrylic resin; 5-9 parts of crosslinking agent; 0.5-2 parts wetting agent; 50-75 parts water; The antistatic agent is prepared using water, MXene dispersion, and conductive polymer as raw materials.

[0006] Optionally, in the raw materials of the antistatic agent, the mass fraction of MXene in the MXene dispersion is 20%; the mass ratio of water, the MXene dispersion, and the conductive polymer is 1:1:1.

[0007] Optionally, the MXene dispersion is Ti3C2Tx.

[0008] Optionally, the Ti3C2Tx dispersion is prepared by reacting LiF and Ti3AlC2 under acidic conditions.

[0009] Optionally, the conductive polymer is PEDOT / PSS.

[0010] Optionally, the waterborne acrylic resin is prepared by solution polymerization using isopropanol as a solvent and acrylic acid monomer as a polymerizing monomer.

[0011] Optionally, the acrylic monomer is composed of acrylic acid, hydroxyethyl acrylate, methyl methacrylate, and n-butyl acrylate.

[0012] Optionally, the acrylic monomer is composed of acrylic acid, hydroxyethyl acrylate, methyl methacrylate and n-butyl acrylate in a mass ratio of (2-4):(2-4):(9-12):(18-24).

[0013] Optionally, the mass ratio of isopropanol to acrylic acid monomer is 2:3.

[0014] Another object of the present invention is to provide an antistatic film, comprising a base film and at least one antistatic coating layer; the antistatic coating layer is obtained by applying the antistatic coating liquid as described above onto the base film and then heat-setting it.

[0015] The beneficial effects of this invention are: The antistatic coating liquid provided by this invention has permanent antistatic properties, thus ensuring the stability of antistatic performance. The antistatic coating prepared by this antistatic coating liquid, after high-temperature cross-linking, has good adhesion to the PET surface, solving the problem of easy peeling of antistatic coatings in the prior art, which reduces the antistatic performance of PET, and avoiding the loss of antistatic performance due to temperature and time. This antistatic coating liquid can introduce an antistatic coating onto the surface of the base film through online coating, avoiding the introduction of antistatic agents into the base film matrix, thereby improving the antistatic performance of the polyester film without affecting the mechanical properties of the polyester film. Detailed Implementation

[0016] The present invention will now be described in further detail. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0017] To address the problem that existing polyester films struggle to simultaneously achieve both antistatic and mechanical properties, this invention provides an antistatic coating liquid. The raw materials of this antistatic coating liquid, by weight, comprise the following components: 1.5-3 parts antistatic agent; 20-36 parts of water-based acrylic resin; 5-9 parts of crosslinking agent; 0.5-2 parts wetting agent; 50-75 parts water; The antistatic agent is prepared from water, MXene dispersion, and conductive polymer.

[0018] In this antistatic agent, MXene is a novel two-dimensional material with a two-dimensional sheet structure similar to graphene and high conductivity. However, due to its sheet structure, MXene is prone to stacking, affecting its electrochemical performance. Therefore, this invention preferably introduces a conductive polymer into the antistatic agent. The molecular chains of the conductive polymer are inserted between the MXene sheets, providing not only pseudocapacitance but also support and preventing MXene sheet stacking. This allows for greater utilization of the surface electrochemical active sites, maximizing the utilization rate of MXene's surface groups. Furthermore, the conductive polymer can co-construct a three-dimensional conductive network with the MXene sheets, maintaining a high specific surface area, which is beneficial for ion transport, and providing continuous electron conduction pathways, synergistically enhancing electrochemical performance.

[0019] Furthermore, antistatic agents and waterborne acrylic resins are simultaneously introduced into the antistatic coating liquid. When the conductive polymer is dispersed into the waterborne acrylic resin matrix, the good compatibility between the conductive polymer and the resin allows the conductive polymer to form a conductive network in the matrix resin, thereby consuming the static charge generated on the resin surface and achieving the purpose of antistatic properties.

[0020] The crosslinking agent of the present invention is preferably selected from at least one of HDI trimer, trimethylolpropane (TMP), aziridine crosslinking agent, and diethylenetriamine (DETA); the wetting agent is preferably selected from at least one of TL-J20, TL-J40, and X-405.

[0021] The antistatic coating liquid can be applied to the surface of a PET base film via online coating and then heat-set to prepare an antistatic coating, thus obtaining an antistatic film.

[0022] The antistatic coating liquid provided by this invention has permanent antistatic properties, thus ensuring the stability of antistatic performance. The antistatic coating prepared by this antistatic coating liquid, after high-temperature cross-linking, has good adhesion to the PET surface, solving the problem of easy peeling of antistatic coatings in the prior art, which reduces the antistatic performance of PET, and avoiding the loss of antistatic performance due to temperature and time. This antistatic coating liquid can introduce an antistatic coating onto the surface of the base film through online coating, avoiding the introduction of antistatic agents into the base film matrix, thereby improving the antistatic performance of the polyester film without affecting the mechanical properties of the polyester film.

[0023] Furthermore, to ensure antistatic performance, the present invention preferably uses MXene dispersion with a mass fraction of 20% in the raw materials of the antistatic agent; and the mass ratio of water, MXene dispersion and conductive polymer is 1:1:1.

[0024] The antistatic coating prepared by the antistatic coating liquid provided by this invention not only improves the antistatic performance, but also reduces the friction coefficient of PET film due to the good dispersibility of nano-inorganic particles, thus solving the problem of difficult winding of some BOPET films in the prior art.

[0025] Specifically, the preferred MXene dispersion of this invention is a Ti3C2Tx dispersion. The oxygen-containing groups on the surface of Ti3C2Tx have electrochemical activity. While improving electrochemical performance, they can form hydrogen bonds or electrostatic interactions with conductive polymer chains. This interaction can anchor the conductive polymer on the surface of Ti3C2Tx, forming a more stable composite structure and preventing Ti3C2Tx from agglomerating in subsequent processing.

[0026] The present invention preferably prepares the Ti3C2Tx dispersion by reacting LiF and Ti3AlC2 under acidic conditions, and preferably the mass ratio of LiF to Ti3AlC2 is 1.34:1.

[0027] In this invention, the conductive polymer in the preferred antistatic agent is PEDOT / PSS. Poly(3,4-ethylenedioxythiophene) (PEDOT) is a derivative of polythiophene and possesses good conductivity. However, due to the infusibility and insolubility of PEDOT, polystyrene sulfonate (PSS) is introduced. PSS not only acts as a charge-balancing dopant, but also, due to the hydrophilic nature of the sulfonate group in PSS, the water-insoluble PEDOT can be encapsulated by the PSS macromolecular chains, allowing it to be uniformly dispersed in water to form a stable aqueous dispersion of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT / PSS). This PEDOT / PSS is a core-shell structured conductive polymer with high mechanical flexibility and excellent dispersibility in water.

[0028] The present invention further preferably uses an antistatic agent prepared according to the following method: According to the formulation, Ti3C2Tx dispersion and PEDOT / PSS were added sequentially to deionized water. The mixture was sonicated at 40 kHz for 30 min, and then homogenized at 12000 rpm for 5 min at room temperature to obtain the antistatic agent.

[0029] The present invention preferably uses isopropanol as a solvent and acrylic acid monomer as a polymerizing monomer to prepare the waterborne acrylic resin by solution polymerization.

[0030] Furthermore, the acrylic monomers of the present invention are preferably composed of acrylic acid, hydroxyethyl acrylate, methyl methacrylate and n-butyl acrylate; specifically, the acrylic monomers are preferably composed of acrylic acid, hydroxyethyl acrylate, methyl methacrylate and n-butyl acrylate in a mass ratio of (2-4):(2-4):(9-12):(18-24); the mass ratio of isopropanol to acrylic monomers is preferably 2:3.

[0031] Specifically, the waterborne acrylic resin is preferably prepared according to the following method: Add 15 ml of isopropanol to a three-necked flask equipped with a tetrafluoroethylene stir bar and a condenser. Then prepare a mixture of monomers (2-4 g acrylic acid, 2-4 g hydroxyethyl acrylate, 9-12 g methyl methacrylate, 18-24 g n-butyl acrylate) and 0.5-1 g AIBN. Weigh 20 wt% of the mixture and add it to the three-necked flask. React at 70 °C for 30 min, then raise the temperature to 75 °C. Add the monomers dropwise over 2 hours and keep the temperature for another 2 hours. During this time, add an appropriate amount of isopropanol (total isopropanol to monomer mass ratio of 2:3). Keep the temperature to 60 °C and add an appropriate amount of triethylamine while stirring to neutralize for 10 min (pH around 7). Finally, add an appropriate amount of water to dilute the mixture and obtain a translucent bluish waterborne acrylic resin.

[0032] The antistatic coating liquid of the present invention is preferably prepared according to the following method: According to the formula, antistatic agents, water-based acrylic resins, crosslinking agents, and wetting agents were compounded in proportion to prepare antistatic coating liquids with different solid contents (20%-40%).

[0033] Another object of the present invention is to provide an antistatic film comprising a base film and at least one antistatic coating layer; the antistatic coating layer is obtained by applying the antistatic coating liquid as described above onto the base film and then heat-setting it.

[0034] Existing techniques for adding antistatic agents during the preparation of polyester film masterbatch can improve the antistatic properties of BOPET film to some extent, but they also have several problems. First, while organic antistatic agents have good compatibility with the PET matrix, they can migrate within the matrix, causing the film's antistatic properties to gradually decrease with temperature and time. Second, inorganic antistatic agents have poor compatibility with PET, and large amounts may significantly reduce the mechanical properties of the polyester film. Furthermore, while some antistatic coatings can improve the antistatic properties of PET film, these properties gradually decrease with temperature and time, which is a significant issue for antistatic coatings.

[0035] Currently, some polyester films introduce antistatic coatings through coating, which improves the antistatic performance of PET films. However, the antistatic performance gradually decreases due to the influence of temperature and time. The antistatic coating in this invention is obtained by applying an antistatic coating liquid onto a base film and then heat-setting it. This allows the antistatic coating to have good adhesion to the surface of the base film after high-temperature cross-linking, solving the problem of easy peeling off of the antistatic coating in the prior art, which reduces the antistatic performance of polyester films.

[0036] The antistatic polyester film provided by this invention has a permanent antistatic coating liquid, thus ensuring the stability of antistatic performance. After high-temperature cross-linking, the antistatic coating has good adhesion to the PET surface, solving the problem of easy peeling of the antistatic coating in the prior art, which reduces the antistatic performance of PET and avoids the loss of antistatic performance due to temperature and time. By introducing the antistatic coating through online coating, the introduction of antistatic agent into the base film matrix is ​​avoided, thereby improving the antistatic performance of the polyester film without affecting the mechanical properties of the polyester film.

[0037] The preferred base film of this invention is a PET film, and more preferably, the base film has an ABA structure. Further, the antistatic polyester film is preferably prepared according to the following process: S1: Preparation of the base film: Open-cell masterbatch and PET chips are mixed evenly according to the formula to form the ABA structure surface layer of the PET film. The mass ratio of open-cell masterbatch in the surface layer is 60-90%. The thickness of the upper and lower surface layers and the proportion of open-cell masterbatch are the same. The core layer is made of pure PET chips, and the thickness ratio of the core layer to the surface layer is 1:9. The raw material melt is first extruded and cast, then biaxially stretched and heat-set to obtain a transparent BOPET film. The longitudinal stretching temperature is 70-100℃, and the stretching ratio is 3-3.5 times. The transverse stretching temperature is 100-120℃, and the stretching ratio is 3-4 times. The heat-setting temperature is 190-230℃, and the time is 10-20s, finally producing a 50-micron BOPET film, i.e., the base film.

[0038] S2: Online coating: Coating is performed using a D-bar wire rod. An online coating station (including a corona treatment device and a coating device) is set between the longitudinal and transverse stretching of BOPET. After the PET film is corona-treated by the corona treatment device, the coating device evenly coats the antistatic coating liquid onto the PET surface. Then, it is cured and cross-linked during transverse stretching and heat setting to form an antistatic coating on the PET film surface, resulting in a BOPET film with a thickness of 50 micrometers.

[0039] S3: Post-processing: The BOPET film obtained in step S2 is cooled, wound up, and slit to obtain the final antistatic BOPET film.

[0040] Throughout the preparation process, we need to maintain a clean environment to avoid impurities affecting the film performance, and at the same time, we need to control the operating parameters of each step to ensure the stability of the film quality.

[0041] The antistatic film provided by this invention has significant improvements in antistatic properties, mechanical properties, and film traction and winding, and has high practical value and broad application prospects.

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0043] Unless otherwise specified, in the base films of the various embodiments and comparative examples of the present invention, the open masterbatch is Yizheng Chemical Fiber FG611 and the PET chips are Yizheng Chemical Fiber FG604.

[0044] Example 1 This embodiment provides a method for preparing an antistatic film, comprising the following steps: Step 1: Preparation of antistatic coating solution. An antistatic coating solution with a solid content of 20% was prepared by mixing 1.5 parts by weight of antistatic agent, 20 parts by weight of water-based acrylic resin, 5 parts by weight of crosslinking agent, 0.5 parts by weight of wetting agent, and 73 parts by weight of pure water.

[0045] The crosslinking agent is HDI trimer; the wetting agent is TL-J20.

[0046] The antistatic agent is prepared according to the following method: A 20% Ti3C2Tx dispersion and PEDOT / PSS were added sequentially to deionized water at a mass ratio of 1:1. The mixture was sonicated at 40 kHz for 30 min, and then homogenized at 12,000 rpm for 5 min at room temperature to obtain the antistatic agent.

[0047] Preparation of Ti3C2Tx dispersion: 1.34 g of LiF was added to 20 mL of HCl and stirred at room temperature for 10 minutes to fully dissolve the LiF, obtaining a LiF / HCl solution. 1 g of Ti3AlC2 was weighed and slowly poured into the LiF / HCl solution. This pouring process generates significant heat. After the liquid stabilizes, it was placed in a 35°C water bath and stirred for 24 hours. After the reaction was complete, the solution was washed with deionized water by centrifugation (3500 rpm, 5 minutes each time). The pH was adjusted to approximately 7, at which point a small amount of Ti3C2Tx had dispersed in the water. The precipitate was then washed into a glass bottle, an appropriate amount of water was added, and the bottle was shaken thoroughly to further separate the Ti3C2Tx flakes. The mixture was then centrifuged at 3500 rpm for 60 minutes, and the supernatant was collected as a 20% (w / w) Ti3C2Tx dispersion. This dispersion was sealed in a glass bottle and stored at 2°C.

[0048] Preparation of waterborne acrylic resin: Aqueous acrylic resin was prepared by solution polymerization. 15 ml of isopropanol was added to a three-necked flask equipped with a tetrafluoroethylene stir bar and a condenser. A mixed monomer mixture (2 g acrylic acid, 2 g hydroxyethyl acrylate, 9 g methyl methacrylate, 18 g n-butyl acrylate, and 0.5 g AIBN) was then prepared. 20 wt% of the mixed monomer mixture was added to the three-necked flask, and the reaction was carried out at 70°C for 30 min. The temperature was then raised to 75°C, and the mixture was added dropwise over 2 hours, followed by a 2-hour holding period. During this time, isopropanol was added as needed (isopropanol to monomer mass ratio of 2:3). The temperature was maintained at 60°C, and while stirring, a suitable amount of triethylamine was added to neutralize the mixture for 10 min (pH approximately 7). Finally, a suitable amount of water was added for dilution, resulting in a translucent, bluish-tinted aqueous acrylic resin.

[0049] Step Two: Preparation of the Base Film. Open-ended masterbatch and PET chips are mixed uniformly at a specific mass ratio to form the surface layer of the PET film's ABA structure. The masterbatch accounts for 90% of the surface layer's mass. The upper and lower surface layers have the same thickness and masterbatch proportion. The core layer is made of pure PET chips, with a core layer to surface layer thickness ratio of 1:9. The raw material melt is first extruded and cast, then the base film undergoes biaxial stretching and heat setting. The longitudinal stretching temperature is 70℃, with a stretching ratio of 3 times. The transverse stretching temperature is 100℃, with a stretching ratio of 3 times. The heat setting temperature is 190℃ for 10 seconds, finally yielding the base film.

[0050] Step 3: Online Coating. Coating is performed using a D-bar wire rod. An online coating station is set up between the longitudinal and transverse stretching of BOPET. After the PET film is corona-treated by a corona device, the coating device evenly coats the PET surface with the coating liquid. Then, it is cured and cross-linked during transverse stretching and heat setting to form an antistatic coating on the PET film surface, finally producing a BOPET film with a thickness of 50 micrometers.

[0051] Step 4: Post-processing. The BOPET film obtained in Step 3 is cooled, wound up, and slit to obtain the final antistatic BOPET film product, denoted as Sample 2.

[0052] Comparative Example 1 This comparative example provides a method for preparing a thin film, comprising the following steps: Step 1: Preparation of online coating solution. An online coating solution was prepared by mixing 21.5 parts by weight of water-based acrylic resin, 5 parts by crosslinking agent, 0.5 parts by wetting agent, and 73 parts by pure water.

[0053] The crosslinking agent is HDI trimer; the wetting agent is TL-J20.

[0054] Waterborne acrylic resin is prepared according to the following method: Aqueous acrylic resin was prepared by solution polymerization. 15 ml of isopropanol was added to a three-necked flask equipped with a tetrafluoroethylene stir bar and a condenser. A mixed monomer mixture (2 g acrylic acid, 2 g hydroxyethyl acrylate, 9 g methyl methacrylate, 18 g n-butyl acrylate, and 0.5 g AIBN) was then prepared. 20 wt% of the mixed monomer mixture was added to the three-necked flask, and the reaction was carried out at 70°C for 30 min. The temperature was then raised to 75°C, and the mixture was added dropwise over 2 hours, followed by a 2-hour holding period. During this time, isopropanol was added as needed (isopropanol to monomer mass ratio of 2:3). The temperature was maintained at 60°C, and while stirring, a suitable amount of triethylamine was added to neutralize the mixture for 10 min (pH approximately 7). Finally, a suitable amount of water was added for dilution, resulting in a translucent, bluish-tinted aqueous acrylic resin.

[0055] Step Two: Preparation of the Base Film. Open-ended masterbatch and PET chips are mixed uniformly at a specific mass ratio to form the surface layer of the PET film's ABA structure. The masterbatch accounts for 90% of the surface layer's mass. The upper and lower surface layers have the same thickness and masterbatch proportion. The core layer is made of pure PET chips, with a core layer to surface layer thickness ratio of 1:9. The raw material melt is first extruded and cast, then the base film undergoes biaxial stretching and heat setting. The longitudinal stretching temperature is 70℃, with a stretching ratio of 3 times. The transverse stretching temperature is 100℃, with a stretching ratio of 3 times. The heat setting temperature is 190℃ for 10 seconds, finally yielding the base film.

[0056] Step 3: Online Coating. Coating is performed using a D-bar wire rod. An online coating station is set up between the longitudinal and transverse stretching of BOPET. After the PET film is corona-treated by a corona device, the coating device evenly coats the PET surface with the coating liquid. Then, it is cured and cross-linked during transverse stretching and heat setting to form an antistatic coating on the PET film surface, finally producing a BOPET film with a thickness of 50 micrometers.

[0057] Step 4: Post-processing. The BOPET film obtained in Step 3 is cooled, wound up, and slit to obtain the final BOPET film product, denoted as Sample 1.

[0058] Example 1, Performance test of Comparative Example 1: Surface resistivity: Tested according to GB / T 1410-2006 standard.

[0059] Coating adhesion test: The adhesion between the PET substrate and the coating was tested according to ASTM D3359.

[0060] Tensile strength at break and elongation at break: tested according to ASTM D-882 standard.

[0061] Light transmittance: Tested according to ASTM D-1746 standard.

[0062] Haze: Tested according to ASTM D-1003 standard.

[0063] The test results are shown in Table 1: Table 1 sample Surface resistivity (Ω) Coating adhesion Tensile breaking strength MD / TD (MPa) Elongation at break (MD / TD) (%) Light transmittance (%) Haze (%) Sample 1 <![CDATA[5.5·10 14 ]]> 4B 213 / 228 106 / 94 91 2.1 Sample 2 <![CDATA[3.4·10 8 ]]> 4B 222 / 241 111 / 98 90 2.2 Table 1 shows the surface resistivity, coating adhesion, tensile strength at break, elongation at break, light transmittance, and haze of Sample 1 and Sample 2. It is evident that the BOPET film prepared in Example 1 of this application possesses excellent antistatic, mechanical, and optical properties; Example 1 improved the antistatic properties of the film without significantly reducing its mechanical and optical properties.

[0064] Example 2 This embodiment provides a method for preparing an antistatic film, comprising the following steps: Step 1: Preparation of antistatic coating solution. Based on the weight proportions, 2 parts antistatic agent, 24 parts water-based acrylic resin, 8 parts crosslinking agent, 1 part wetting agent, and 65 parts pure water were combined to prepare an online antistatic coating solution with a solid content of 30%.

[0065] The crosslinking agent is trimethylolpropane (TMP); the wetting agent is TL-J40.

[0066] The antistatic agent is prepared according to the following method: A 20% Ti3C2Tx dispersion and PEDOT / PSS were added sequentially to deionized water at a mass ratio of 1:1. The mixture was sonicated at 40 kHz for 30 min, and then homogenized at 12,000 rpm for 5 min at room temperature to obtain the antistatic agent.

[0067] Preparation of Ti3C2Tx dispersion: 1.34 g of LiF was added to 20 mL of HCl and stirred at room temperature for 10 minutes to fully dissolve the LiF, obtaining a LiF / HCl solution. 1 g of Ti3AlC2 was slowly poured into the LiF / HCl solution. This pouring process generates significant heat. After the liquid stabilizes, it was placed in a 35°C water bath and stirred for 24 hours. After the reaction was complete, the solution was washed with deionized water by centrifugation (3500 rpm, 5 minutes each time). The pH was adjusted to approximately 7, at which point a small amount of Ti3C2Tx had dispersed in the water. The precipitate was then washed into a glass bottle, an appropriate amount of water was added, and the bottle was shaken thoroughly to further separate the Ti3C2Tx flakes. The mixture was then centrifuged at 3500 rpm for 60 minutes, and the supernatant was collected as the Ti3C2Tx dispersion. This dispersion was sealed in a glass bottle and stored at 2°C.

[0068] Preparation of waterborne acrylic resin: Aqueous acrylic resin was prepared by solution polymerization. 15 ml of isopropanol was added to a three-necked flask equipped with a tetrafluoroethylene stir bar and a condenser. A mixed monomer mixture (2 g acrylic acid, 2 g hydroxyethyl acrylate, 9 g methyl methacrylate, 18 g n-butyl acrylate, and 0.5 g AIBN) was then prepared. 20 wt% of the mixed monomer mixture was added to the three-necked flask, and the reaction was carried out at 70°C for 30 min. The temperature was then raised to 75°C, and the mixture was added dropwise over 2 hours, followed by a 2-hour holding period. During this time, isopropanol was added as needed (isopropanol to monomer mass ratio of 2:3). The temperature was maintained at 60°C, and while stirring, a suitable amount of triethylamine was added to neutralize the mixture for 10 min (pH approximately 7). Finally, a suitable amount of water was added for dilution, resulting in a translucent, bluish-tinted aqueous acrylic resin.

[0069] Step Two: Preparation of the Base Film. Open-ended masterbatch and PET chips are mixed uniformly at a specific mass ratio to form the surface layer of the ABA structure PET film. The masterbatch accounts for 75% of the surface layer's mass. The upper and lower surface layers have the same thickness and masterbatch proportion. The core layer is made of pure PET chips, with a core layer to surface layer thickness ratio of 1:9. The raw material melt is first extruded and cast, then the base film undergoes biaxial stretching and heat setting. The longitudinal stretching temperature is 85℃, with a stretching ratio of 3.2 times. The transverse stretching temperature is 110℃, with a stretching ratio of 3.5 times. The heat setting temperature is 210℃ for 10 seconds, finally yielding the base film.

[0070] Step 3: Online Coating. Coating is performed using a D-bar wire rod. An online coating station is set up between the longitudinal and transverse stretching of BOPET. After the PET film is corona-treated by a corona device, the coating device evenly coats the PET surface with the coating liquid. Then, it is cured and cross-linked during transverse stretching and heat setting to form an antistatic coating on the PET film surface, finally producing a BOPET film with a thickness of 50 micrometers.

[0071] Step 4: Post-processing. The BOPET film obtained in Step 3 is cooled, wound up, and slit to obtain the final antistatic BOPET film product, denoted as Sample 4.

[0072] Comparative Example 2 This comparative example provides a method for preparing a thin film, comprising the following steps: Step 1: Preparation of antistatic online coating solution. An online coating solution was prepared by mixing 26 parts by weight of water-based acrylic resin, 8 parts by crosslinking agent, 1 part by wetting agent, and 65 parts by pure water.

[0073] The crosslinking agent is trimethylolpropane (TMP); the wetting agent is TL-J40.

[0074] Waterborne acrylic resin is prepared according to the following method: Aqueous acrylic resin was prepared by solution polymerization. 15 ml of isopropanol was added to a three-necked flask equipped with a tetrafluoroethylene stir bar and a condenser. A mixed monomer mixture (2 g acrylic acid, 2 g hydroxyethyl acrylate, 9 g methyl methacrylate, 18 g n-butyl acrylate, and 0.5 g AIBN) was then prepared. 20 wt% of the mixed monomer mixture was added to the three-necked flask, and the reaction was carried out at 70°C for 30 min. The temperature was then raised to 75°C, and the mixture was added dropwise over 2 hours, followed by a 2-hour holding period. During this time, isopropanol was added as needed (isopropanol to monomer mass ratio of 2:3). The temperature was maintained at 60°C, and while stirring, a suitable amount of triethylamine was added to neutralize the mixture for 10 min (pH approximately 7). Finally, a suitable amount of water was added for dilution, resulting in a translucent, bluish-tinted aqueous acrylic resin.

[0075] Step Two: Preparation of the Base Film. Open-ended masterbatch and PET chips are mixed uniformly at a specific mass ratio to form the surface layer of the ABA structure PET film. The masterbatch accounts for 75% of the surface layer's mass. The upper and lower surface layers have the same thickness and masterbatch proportion. The core layer is made of pure PET chips, with a core layer to surface layer thickness ratio of 1:9. The raw material melt is first extruded and cast, then the base film undergoes biaxial stretching and heat setting. The longitudinal stretching temperature is 85℃, with a stretching ratio of 3.2 times. The transverse stretching temperature is 110℃, with a stretching ratio of 3.5 times. The heat setting temperature is 210℃ for 10 seconds, finally yielding the base film.

[0076] Step 3: Online Coating. Coating is performed using a D-bar wire rod. An online coating station is set up between the longitudinal and transverse stretching of BOPET. After the PET film is corona-treated by a corona device, the coating device evenly coats the PET surface with the coating liquid. Then, it is cured and cross-linked during transverse stretching and heat setting to form an antistatic coating on the PET film surface, finally producing a BOPET film with a thickness of 50 micrometers.

[0077] Step 4: Post-processing. The BOPET film obtained in Step 3 is cooled, wound up, and slit to obtain the final antistatic BOPET film product, denoted as Sample 3.

[0078] Performance tests of Example 2 and Comparative Example 2: Surface resistivity: Tested according to GB / T 1410-2006 standard.

[0079] Coating adhesion test: The adhesion between the PET substrate and the coating was tested according to ASTM D3359.

[0080] Tensile strength at break and elongation at break: tested according to ASTM D-882 standard.

[0081] Light transmittance: Tested according to ASTM D-1746 standard.

[0082] Haze: Tested according to ASTM D-1003 standard.

[0083] The test results are shown in Table 2: Table 2 sample Surface resistivity (Ω) Coating adhesion Tensile breaking strength MD / TD (MPa) Elongation at break (MD / TD) (%) Light transmittance (%) Haze (%) Sample 3 <![CDATA[4.4·10 14 ]]> 5B 208 / 215 108 / 102 90 2.2 Sample 4 <![CDATA[2.7·10 7 ]]> 5B 214 / 225 116 / 109 90 2.5 Table 2 shows the surface resistivity, coating adhesion, tensile strength at break, elongation at break, light transmittance, and haze of samples 3 and 4. It is evident that the BOPET film prepared in Example 2 of this application possesses excellent antistatic, mechanical, and optical properties; Example 2 improved the antistatic properties of the film without significantly reducing its mechanical and optical properties.

[0084] Example 3 This embodiment provides a method for preparing an antistatic film, comprising the following steps: Step 1: Preparation of antistatic coating solution. Based on the weight proportions, 3 parts antistatic agent, 36 parts water-based acrylic resin, 9 parts crosslinking agent, 2 parts wetting agent, and 50 parts pure water were combined to prepare an online antistatic coating solution with a solid content of 40%.

[0085] The crosslinking agent is aziridine crosslinking agent; the wetting agent is X-405.

[0086] The antistatic agent is prepared according to the following method: Preparation of the antistatic agent. A 20% (w / w) Ti3C2Tx dispersion and PEDOT / PSS were added sequentially to deionized water at a mass ratio of 1:1. The mixture was sonicated at 40 kHz for 30 min, followed by homogenization at 12000 rpm for 5 min at room temperature to obtain the antistatic agent.

[0087] Preparation of Ti3C2Tx dispersion: 1.34 g of LiF was added to 20 mL of HCl and stirred at room temperature for 10 minutes to fully dissolve the LiF, obtaining a LiF / HCl solution. 1 g of Ti3AlC2 was weighed and slowly poured into the LiF / HCl solution. This pouring process generates significant heat. After the liquid stabilizes, it was placed in a 35°C water bath and stirred for 24 hours. After the reaction was complete, the solution was washed with deionized water by centrifugation (3500 rpm, 5 minutes each time). The pH was adjusted to approximately 7, at which point a small amount of Ti3C2Tx had dispersed in the water. The precipitate was then washed into a glass bottle, an appropriate amount of water was added, and the bottle was shaken thoroughly to further separate the Ti3C2Tx flakes. The mixture was then centrifuged at 3500 rpm for 60 minutes, and the supernatant was collected as a 20% Ti3C2Tx dispersion. This dispersion was sealed in a glass bottle and stored at 2°C.

[0088] Preparation of waterborne acrylic resin: Aqueous acrylic resin was prepared by solution polymerization. 15 ml of isopropanol was added to a three-necked flask equipped with a tetrafluoroethylene stir bar and a condenser. A mixed monomer mixture (2 g acrylic acid, 2 g hydroxyethyl acrylate, 9 g methyl methacrylate, 18 g n-butyl acrylate, and 0.5 g AIBN) was then prepared. 20 wt% of the mixed monomer mixture was added to the three-necked flask, and the reaction was carried out at 70°C for 30 min. The temperature was then raised to 75°C, and the mixture was added dropwise over 2 hours, maintaining this temperature for another 2 hours. During this period, isopropanol was added as needed (isopropanol to monomer mass ratio of 2:3). The temperature was maintained at 60°C, and while stirring, a suitable amount of triethylamine was added to neutralize the resin for 10 min (to approximately pH 7). Finally, water was added to dilute the resin, resulting in a translucent, bluish-white aqueous acrylic resin.

[0089] Step Two: Preparation of the Base Film. Open-ended masterbatch and PET chips are mixed uniformly at a specific mass ratio to form the surface layer of the PET film's ABA structure. The masterbatch accounts for 60% of the surface layer's mass. The upper and lower surface layers have the same thickness and masterbatch proportion. The core layer is made of pure PET chips, with a core layer to surface layer thickness ratio of 1:9. The raw material melt is first extruded and cast, then the base film undergoes biaxial stretching and heat setting. The longitudinal stretching temperature is 100℃, with a stretching ratio of 3.5 times. The transverse stretching temperature is 120℃, with a stretching ratio of 4 times. The heat setting temperature is 230℃ for 20 seconds, finally yielding the base film.

[0090] Step 3: Online Coating. Coating is performed using a D-bar wire rod. An online coating station is set up between the longitudinal and transverse stretching of BOPET. After the PET film is corona-treated by a corona device, the coating device evenly coats the PET surface with the coating liquid. Then, it is cured and cross-linked during transverse stretching and heat setting to form an antistatic coating on the PET film surface, finally producing a BOPET film with a thickness of 50 micrometers.

[0091] Step 4: Post-processing. The BOPET film obtained in Step 3 is cooled, wound up, and slit to obtain the final antistatic BOPET film product, designated as Sample 6.

[0092] Comparative Example 3 This comparative example provides a method for preparing a thin film, comprising the following steps: Step 1: Preparation of online coating solution. An online coating solution was prepared by mixing 39 parts by weight of water-based acrylic resin, 9 parts by crosslinking agent, 2 parts by wetting agent, and 50 parts by pure water.

[0093] The crosslinking agent is aziridine crosslinking agent; the wetting agent is X-405.

[0094] Waterborne acrylic resin is prepared according to the following method: Aqueous acrylic resin was prepared by solution polymerization. 15 ml of isopropanol was added to a three-necked flask equipped with a tetrafluoroethylene stir bar and a condenser. A mixed monomer mixture (2 g acrylic acid, 2 g hydroxyethyl acrylate, 9 g methyl methacrylate, 18 g n-butyl acrylate, and 0.5 g AIBN) was then prepared. 20 wt% of the mixed monomer mixture was added to the three-necked flask, and the reaction was carried out at 70°C for 30 min. The temperature was then raised to 75°C, and the mixture was added dropwise over 2 hours, followed by a 2-hour holding period. During this time, isopropanol was added as needed (isopropanol to monomer mass ratio of 2:3). The temperature was maintained at 60°C, and while stirring, a suitable amount of triethylamine was added to neutralize the mixture for 10 min (pH approximately 7). Finally, a suitable amount of water was added for dilution, resulting in a translucent, bluish-tinted aqueous acrylic resin.

[0095] Step Two: Preparation of the Base Film. Open-ended masterbatch and PET chips are mixed uniformly at a specific mass ratio to form the surface layer of the PET film's ABA structure. The masterbatch accounts for 60% of the surface layer's mass. The upper and lower surface layers have the same thickness and masterbatch proportion. The core layer is made of pure PET chips, with a core layer to surface layer thickness ratio of 1:9. The raw material melt is first extruded and cast, then the base film undergoes biaxial stretching and heat setting. The longitudinal stretching temperature is 100℃, with a stretching ratio of 3.5 times. The transverse stretching temperature is 120℃, with a stretching ratio of 4 times. The heat setting temperature is 230℃ for 20 seconds, finally yielding the base film.

[0096] Step 3: Online Coating. Coating is performed using a D-bar wire rod. An online coating station is set up between the longitudinal and transverse stretching of BOPET. After the PET film is corona-treated by a corona device, the coating device evenly coats the PET surface with the coating liquid. Then, it is cured and cross-linked during transverse stretching and heat setting to form an antistatic coating on the PET film surface, finally producing a BOPET film with a thickness of 50 micrometers.

[0097] Step 4: Post-processing. The BOPET film obtained in Step 3 is cooled, wound up, and slit to obtain the final antistatic BOPET film product, which is designated as Sample 5.

[0098] Performance tests of Example 3 and Comparative Example 3: Surface resistivity: Tested according to GB / T 1410-2006 standard.

[0099] Coating adhesion test: The adhesion between the PET substrate and the coating was tested according to ASTM D3359.

[0100] Tensile strength at break and elongation at break: tested according to ASTM D-882 standard.

[0101] Light transmittance: Tested according to ASTM D-1746 standard.

[0102] Haze: Tested according to ASTM D-1003 standard.

[0103] The test results are shown in Table 3: Table 3 sample Surface resistivity (Ω) Coating adhesion Tensile breaking strength MD / TD (MPa) Elongation at break (MD / TD) (%) Light transmittance (%) Haze (%) Sample 5 <![CDATA[4.7·10 14 ]]> 5B 225 / 237 117 / 108 91 2.5 Sample Six <![CDATA[1.3·10 6 ]]> 5B 233 / 246 124 / 113 90 2.7 Table 3 shows the surface resistivity, coating adhesion, tensile strength at break, elongation at break, light transmittance, and haze of samples 5 and 6. It is evident that the BOPET film prepared in Example 3 of this application possesses excellent antistatic, mechanical, and optical properties; Example 3 improved the antistatic properties of the film without significantly reducing its mechanical and optical properties.

[0104] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. An antistatic coating liquid, characterized in that, The raw materials of the antistatic coating liquid, by weight, include the following components: 1.5-3 parts antistatic agent; 20-36 parts of water-based acrylic resin; 5-9 parts of crosslinking agent; 0.5-2 parts wetting agent; 50-75 parts water; The antistatic agent is prepared using water, MXene dispersion, and conductive polymer as raw materials.

2. The antistatic coating liquid as described in claim 1, characterized in that, In the raw materials of the antistatic agent, the MXene dispersion contains 20% MXene by mass; the mass ratio of water, the MXene dispersion, and the conductive polymer is 1:1:

1.

3. The antistatic coating liquid as described in claim 1, characterized in that, The MXene dispersion is a Ti3C2Tx dispersion.

4. The antistatic coating liquid as described in claim 3, characterized in that, The Ti3C2Tx dispersion was prepared by reacting LiF and Ti3AlC2 under acidic conditions.

5. The antistatic coating liquid as described in claim 1, characterized in that, The conductive polymer is PEDOT / PSS.

6. The antistatic coating liquid according to any one of claims 1-5, characterized in that, The waterborne acrylic resin is prepared by solution polymerization using isopropanol as solvent and acrylic acid monomer as polymerizing monomer.

7. The antistatic coating liquid as described in claim 6, characterized in that, The acrylic monomer is composed of acrylic acid, hydroxyethyl acrylate, methyl methacrylate, and n-butyl acrylate.

8. The antistatic coating liquid as described in claim 7, characterized in that, The acrylic monomer is composed of acrylic acid, hydroxyethyl acrylate, methyl methacrylate and n-butyl acrylate in a mass ratio of (2-4):(2-4):(9-12):(18-24).

9. The antistatic coating liquid as described in claim 6, characterized in that, The mass ratio of isopropanol to acrylic acid monomer is 2:

3.

10. An antistatic film, characterized in that, It includes a base film and at least one antistatic coating; the antistatic coating is obtained by applying the antistatic coating liquid as described in any one of claims 1-9 onto the base film and then heat-setting it.