A quick exhaust weatherable antistatic screen protection film and a preparation method thereof

Abstract

The application discloses a kind of quick exhaust weather-resistant antistatic screen protection film and preparation method thereof, and the protection film includes polyester base material layer and pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is formed by coating liquid through heat curing, and the raw material components of coating liquid include: hydroxyl-terminated hyperbranched polyurethane prepolymer, isocyanate derivative containing UPy group, isocyanate-terminated polyether-lithium salt complex, fluorine-containing siloxane surfactant, curing agent, light stabilizer, ultraviolet absorber, catalyst and solvent.The application is based on hyperbranched polyurethane skeleton, realizes self-repair, long-lasting antistatic, low adhesion, quick exhaust and weather-resistant glue-free in the same pressure-sensitive adhesive layer.

Description

Technical Field

[0001] This invention relates to the field of protective film technology, and in particular to a fast-venting, weather-resistant, antistatic screen protective film and its preparation method. Background Technology

[0002] Screen protectors are widely used for surface protection of optical displays, and their antistatic properties, self-healing properties, and weather resistance directly affect display performance and lifespan. Currently, some technologies employ online coating processes to coat polyurethane pressure-sensitive adhesive onto antistatic substrates to simplify the manufacturing process; others utilize release film transfer with lotus leaf-like micro-nano structures to impart superhydrophobic and self-healing functions to the polyurethane film.

[0003] However, the self-healing properties of polyurethane pressure-sensitive adhesives require low crosslinking density to maintain chain segment mobility, while long-term weather-resistant and residue-resistant adhesives require high crosslinking density to resist creep. The two form an inherent mutual exclusion of "crosslinking degree - self-healing - weather resistance". When antistatic agents are added in a blending manner, they not only face migration and precipitation and damp heat failure, but their ion transport efficiency also decreases sharply with the increase of crosslinking density. In addition, the micro-nano structure cannot be maintained during the online coating-biaxial stretching process due to the viscoelastic flow of the polymer, which makes the superhydrophobic function incompatible with the high-efficiency process. Summary of the Invention

[0004] The purpose of this invention is to provide a fast-venting, weather-resistant, antistatic screen protector and its preparation method, so as to solve at least one of the technical problems of the prior art.

[0005] In a first aspect, the present invention provides a fast-venting, weather-resistant, antistatic screen protector, comprising a polyester substrate layer and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is formed by thermosetting a coating liquid, and the coating liquid comprises the following raw material components in parts by mass: 100 parts of hydroxyl-terminated hyperbranched polyurethane prepolymer; 10 to 30 parts of isocyanate derivatives containing UPy groups; 8 to 25 parts of isocyanate-terminated polyether-lithium salt complex; 0.5 to 2 parts of fluorinated siloxane surfactant; 5 to 15 parts of curing agent; Light stabilizer 0.5 to 2 parts; 0.5 to 2 parts of ultraviolet absorber; Catalyst: 0.05 to 0.2 parts; Solvent: 180-280 parts.

[0006] Among them, the hydroxyl-terminated hyperbranched polyurethane prepolymer is used as the main resin of the pressure-sensitive adhesive. Its hyperbranched topology has a three-dimensional dendritic molecular configuration, and the degree of entanglement between molecular chains is significantly lower than that of linear polymers, which endows the pressure-sensitive adhesive layer with low adhesion and rapid air release. At the same time, the hyperbranched skeleton provides a large number of terminal active sites for grafting self-healing functional units and antistatic functional units.

[0007] Isocyanate derivatives containing UPy groups graft UPy (2-ureido-4[1H]-pyrimidinone) groups onto the ends of the hyperbranched backbone by reacting their isocyanate groups with the terminal hydroxyl groups of the hyperbranched polyurethane prepolymer. The UPy groups can form quadruple hydrogen bonds, constituting a reversible physical cross-linking network. When scratches occur on the surface of the pressure-sensitive adhesive layer, the quadruple hydrogen bonds break preferentially over covalent bonds to dissipate mechanical energy, and then the scratches self-heal through hydrogen bond recombination at room temperature.

[0008] The isocyanate-terminated polyether-lithium salt complex reacts with the terminal hydroxyl groups of the hyperbranched prepolymer to covalently bond the lithium salt complex to the end of the hyperbranched backbone. Lithium ions are transported in the polyethylene glycol segments through a chain-movement-assisted ion hopping mechanism, which endows the pressure-sensitive adhesive layer with durable and stable antistatic properties. Furthermore, due to the covalent bonding, the antistatic components do not migrate or precipitate during long-term use and humid heat aging.

[0009] Fluorosiloxane surfactants contain fluorosilicone low surface energy segments and terminal isocyanate groups. During the coating and drying process, the fluorosilicone segments automatically migrate and accumulate to the adhesive / air interface due to the difference in surface tension. The terminal isocyanate groups react with the active hydrogen of the polyurethane backbone to form covalent bonds and anchor, forming a molecular-level hydrophobic layer with a thickness of less than 5 nm on the adhesive surface, thus achieving antifouling and easy-to-clean functions.

[0010] In some embodiments, the number-average molecular weight of the hydroxyl-terminated hyperbranched polyurethane prepolymer is 8000 g / mol to 20000 g / mol, and the terminal hydroxyl functionality is 5 to 10.

[0011] Furthermore, the hydroxyl-terminated hyperbranched polyurethane prepolymer can be prepared by a method comprising the following steps: performing a melt transesterification reaction between diethanolamine and dimethyl adipate under vacuum conditions to obtain a hydroxyl-terminated hyperbranched polyester core; performing an addition reaction between the hydroxyl-terminated hyperbranched polyester core and isophorone diisocyanate in the presence of a catalyst to obtain the hydroxyl-terminated hyperbranched polyurethane prepolymer; wherein the molar ratio of diethanolamine to dimethyl adipate is 5:3.

[0012] Optionally, the molten transesterification reaction is carried out at 160°C and a vacuum of -0.095 MPa for 4 hours, with continuous removal of the byproduct methanol during the reaction. The ratio of the amount of isophorone diisocyanate added to the molar number of terminal hydroxyl groups in the hyperbranched polyester core is 0.3:1, that is, approximately 70% of the terminal hydroxyl groups are retained for subsequent grafting and crosslinking reactions. The catalyst for the addition reaction is dibutyltin dilaurate, added at 0.05% of the total mass of the reactants, at a reaction temperature of 80°C, for a reaction time of 3 hours.

[0013] In some embodiments, the isocyanate derivative containing the UPy group is 6-methyl-2-(6-isocyanate-hexyl)ureido-4[1H]-pyrimidinone. The carbonyl and imine groups on the UPy ring can form a complementary quadruple hydrogen bond array of AADD-DDAA.

[0014] Furthermore, the isocyanate derivative containing the UPy group can be prepared by a method including the following steps: reacting 2-amino-4-hydroxy-6-methylpyrimidine with hexamethylene diisocyanate in an anhydrous solvent under nitrogen protection, at a reaction temperature of 100°C for 24 hours, and removing unreacted hexamethylene diisocyanate and solvent after the reaction to obtain the isocyanate derivative containing the UPy group.

[0015] In some embodiments, the terminal isocyanate-based polyether-lithium salt complex is a coordination complex of terminal isocyanate-based polyethylene glycol and bis(trifluoromethanesulfonyl)imide, wherein the number-average molecular weight of the polyethylene glycol is 2000 g / mol to 5000 g / mol, and the molar ratio of lithium ions to polyethylene glycol repeating units is 1:(6~12).

[0016] Further, the terminal isocyanate-based polyether-lithium salt complex can be prepared by a method comprising the following steps: reacting methoxy polyethylene glycol (mPEG, number average molecular weight 2000~5000 g / mol) with toluene-2,4-diisocyanate (TDI) in the presence of a catalyst to obtain a terminal isocyanate-based polyethylene glycol prepolymer; and performing a coordination complexation reaction between the terminal isocyanate-based polyethylene glycol prepolymer and lithium bis(trifluoromethanesulfonylimide) (LiTFSI, CAS No. 90076-65-6) in an anhydrous solvent to obtain the terminal isocyanate-based polyether-lithium salt complex.

[0017] Optionally, the molar ratio of methoxy polyethylene glycol to toluene-2,4-diisocyanate is 1:1.2, the catalyst is dibutyltin dilaurate, and the addition amount is 0.05% of the total mass of the reactants. The reaction temperature is 60℃, and the reaction time is 3 h. In the coordination complexation reaction, the molar ratio of lithium ions to polyethylene glycol repeating units is 1:(6~12), the reaction solvent is anhydrous acetonitrile, the reaction temperature is room temperature, and the reaction time is 12 h. The coordination complexation reaction should be carried out under nitrogen protection, the solvent used should be anhydrous, and the water content of the reaction system should be less than 500 ppm.

[0018] In some embodiments, the fluorinated siloxane surfactant is an isocyanate-terminated polydimethylsiloxane-perfluoropolyether-polyethylene glycol triblock copolymer.

[0019] Further, the fluorinated siloxane surfactant is prepared by a method comprising the following steps: hydrosilylation of a single-ended hydrogenated silicone oil with an allyl-terminated perfluoropolyether in the presence of a platinum catalyst to obtain a polydimethylsiloxane-perfluoropolyether diblock copolymer; further hydrosilylation of the diblock copolymer with an allyl-terminated polyethylene glycol to obtain a polydimethylsiloxane-perfluoropolyether-polyethylene glycol triblock copolymer; and reaction of the triblock copolymer with hexamethylene diisocyanate to obtain the fluorinated siloxane surfactant.

[0020] Optionally, the molar ratio of single-terminated hydrogenated silicone oil (H-PDMS, number average molecular weight 2000 g / mol), allyl-terminated perfluoropolyether (PFPE-allyl, number average molecular weight 1500 g / mol), and allyl-terminated polyethylene glycol (PEO-allyl, number average molecular weight 800 g / mol) is 1:1.2:1.2; the hydrogenation silylation reaction is carried out in toluene solvent at 80°C for 4 h, the platinum catalyst is an isopropanol solution of chloroplatinic acid, and the platinum concentration is 20 ppm; the ratio of the amount of hexamethylene diisocyanate added to the molar number of hydroxyl groups in the triblock copolymer is 1.5:1, the reaction temperature is 80°C, and the reaction time is 2 h. In this surfactant, the polydimethylsiloxane segments (surface energy approximately 20 mN / m) and the perfluoropolyether segments (surface energy approximately 12 mN / m) provide low surface tension-driven migration, and the terminal isocyanate groups provide chemical anchoring ability with the polyurethane backbone.

[0021] In some embodiments, the curing agent is an aliphatic isocyanate curing agent, the light stabilizer is a hindered amine light stabilizer, the catalyst is an organotin catalyst, and the solvent is a mixed solvent of methyl ethyl ketone and ethyl acetate.

[0022] Optionally, the curing agent may be selected from one or more of hexamethylene diisocyanate trimer (HDI trimer, such as Covestro Desmodur N3390 or N3300), isophorone diisocyanate trimer (IPDI trimer, such as Covestro Desmodur Z4470), and hexamethylene diisocyanate biuret (such as Covestro Desmodur N75); the light stabilizer may be selected from bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate (CAS No. 41556-26-7); the ultraviolet absorber may be selected from 2-[4-[(2-hydroxy-3-dodecoxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine (BASF Tinuvin 400); and the catalyst may be dibutyltin dilaurate.

[0023] Secondly, the present invention also provides a method for preparing a fast-venting, weather-resistant, antistatic screen protector, comprising the following steps: The hydroxyl-terminated hyperbranched polyurethane prepolymer was mixed evenly with a solvent, and then an isocyanate derivative containing UPy groups and an isocyanate-terminated polyether-lithium salt complex were added. The mixture was stirred at 50℃±5℃ for 1.5h~2.5h, cooled to room temperature, and then a fluorosiloxane surfactant, a light stabilizer, an ultraviolet absorber and a catalyst were added and stirred evenly to obtain a mixture. Add a curing agent to the mixture, stir until homogeneous and degas to obtain a coating liquid; The coating liquid is applied to the surface of the polyester substrate layer, and after biaxial stretching and thermosetting, a release film is laminated, wound up, and cured to obtain a screen protector film.

[0024] The mixing of the hydroxyl-terminated hyperbranched polyurethane prepolymer and solvent was carried out at room temperature, with stirring time of 30 min until completely dissolved. An isocyanate derivative containing UPy groups and a hydroxyl-terminated isocyanate-based polyether-lithium salt complex were added at 50℃±5℃ and stirred for 1.5h~2.5h. This was to allow the NCO groups in UPy-NCO and PEO-LiTFSI-NCO to undergo an urethane reaction with the terminal hydroxyl groups of the hyperbranched prepolymer, grafting the UPy groups and lithium salt complex onto the ends of the hyperbranched framework. After cooling to room temperature, a fluorosiloxane surfactant, light stabilizer, UV absorber, and catalyst were added. Because the reaction rate between NCO and hydroxyl groups is extremely low at room temperature, the terminal NCO of the fluorosiloxane surfactant will not react significantly before coating, ensuring sufficient migration time during subsequent drying. Adding a curing agent just before coating and stirring at room temperature prevents premature cross-linking and gelation of the coating solution during preparation, ensuring a pot life of at least 2h.

[0025] Optionally, the total thickness of the polyester substrate layer is 38μm~75μm, and the thickness of the pressure-sensitive adhesive layer is 3μm~5μm; the polyester substrate layer may be a biaxially oriented polyethylene terephthalate film, and the release film is a fluorinated release film with a release force of less than 5g / inch.

[0026] Optionally, the solid content of the coating liquid is 38%~42%, and the thickness of the coated wet film is 35μm~45μm; the thermosetting includes a three-stage gradient baking: the first stage baking temperature is 100℃ and the baking time is 30s; the second stage baking temperature is 120℃ and the baking time is 30s; the third stage baking temperature is 140℃ and the baking time is 30s; the curing temperature is 50℃ and the time is 48h; and the film is left to stand or degas under reduced pressure for 5min~10min.

[0027] Optionally, before the coating step, the surface of the polyester substrate layer is subjected to corona treatment to make the surface tension of the polyester substrate layer greater than 50 mN / m; the power density of the corona treatment is 30 W·min / m²~50 W·min / m², the electrode spacing is 1.5 mm~2.5 mm, and the coating is performed within 10 seconds after the corona treatment to avoid the decay of the corona effect.

[0028] In some embodiments, the biaxial stretching includes longitudinal stretching and transverse stretching. The longitudinal stretching has a stretching ratio of 3 to 3.5 times, and the transverse stretching has a stretching ratio of 3 to 3.5 times. The transverse stretching is performed at 80°C to 100°C. The longitudinal stretching is performed after the cast sheet has cooled, with a stretching temperature of 80°C to 90°C. The transverse stretching is performed in a transverse stretching section, with the transverse stretching temperature set at 80°C to 100°C. At this temperature, the coating liquid is in a viscous flow state, allowing it to stretch and thin synchronously with the substrate, reducing the wet film thickness from 35μm to 45μm to approximately 11μm to 16μm.

[0029] Compared with the prior art, the present invention has the following beneficial effects: This invention, based on a hyperbranched polyurethane framework, achieves a synergistic unity of self-healing, durable antistatic properties, low adhesion, rapid degassing, and weather resistance with no residue within a single pressure-sensitive adhesive layer. Specifically, UPy quadruple hydrogen bonds provide reversible physical crosslinking for room-temperature self-healing, while the chemical crosslinking network resists creep to ensure long-term weather resistance, breaking the triangular mutual exclusion of crosslinking degree, self-healing, and weather resistance; lithium salt complexes are covalently bonded to the ends of the framework, endowing the pressure-sensitive adhesive layer with double-sided non-migrating antistatic properties, overcoming the migration failure defects of blended antistatic agents; fluorinated siloxane surfactants migrate and anchor to form a molecular-level hydrophobic layer, circumventing the inherent bottlenecks of physical micro / nano structures being not wear-resistant and incompatible with online stretching processes; all functions are integrated into a single adhesive layer, supporting online coating and biaxial stretching in a single molding process, combining high performance and low cost. Detailed Implementation

[0030] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] As used herein, the terms “prepared from” and “comprising” are synonymous. The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0032] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, it should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Unless otherwise specified, the raw materials used in the following examples and comparative examples are commercially available industrial products, and all conditions not otherwise specified are conventional.

[0034] Preparation Example 1: Preparation of hydroxyl-terminated hyperbranched polyurethane prepolymer In a 500 mL four-necked flask equipped with a stirrer, condenser, and thermometer, 52.5 g (0.5 mol) of diethanolamine and 52.2 g (0.3 mol) of dimethyl adipic acid were added. The mixture was heated to 160 °C under nitrogen protection and subjected to transesterification under a vacuum of -0.095 MPa for 4 h. The byproduct methanol (approximately 15 mL) was collected to obtain a hydroxyl-terminated hyperbranched polyester core. The hydroxyl value was determined by end-group titration, and the number average molecular weight was calculated to be approximately 320. 0 g / mol, with approximately 7.5 terminal hydroxyl groups; cooled to 80℃, 19.6 g (0.088 mol) of isophorone diisocyanate and 0.04 g of dibutyltin dilaurate were added, and the mixture was reacted at 80℃ for 3 h to obtain a hydroxyl-terminated hyperbranched polyurethane prepolymer; the number average molecular weight Mn was determined to be 12500 g / mol and the dispersion PDI was determined to be 1.6 by gel permeation chromatography (GPC); the number of remaining terminal hydroxyl groups was determined to be 5.3 by end-group titration.

[0035] Preparation Example 2: Preparation of an isocyanate derivative containing the UPy group (6-methyl-2-(6-isocyanate-hexyl)ureido-4[1H]-pyrimidinone) In a 250 mL flask, 12.5 g (0.10 mol) of 2-amino-4-hydroxy-6-methylpyrimidine and 67.2 g (0.40 mol) of hexamethylene diisocyanate were added, followed by 50 mL of anhydrous N,N-dimethylformamide. The mixture was reacted at 100 °C for 24 h under nitrogen protection. After the reaction was completed, unreacted HDI and DMF were removed by vacuum distillation (80 °C, -0.095 MPa) to obtain a white solid product, 6-methyl-2-(6-isocyanate hexyl)ureido-4[1H]-pyrimidinone (approximately 28 g), with a yield of 82%. The product was confirmed by Fourier transform infrared spectroscopy (FT-IR, KBr pellet method). A peak of NH stretching vibration appears at this location. The characteristic absorption peak of NCO appears at this location. and Characteristic absorption peaks of the C=O and C=N of the UPy ring appear at the location.

[0036] Preparation Example 3: Preparation of Isocyanate-terminated polyether-lithium salt complexes Under nitrogen protection throughout the process, 40 g (0.020 mol) of methoxy polyethylene glycol and 100 mL of anhydrous acetonitrile (moisture content <500 ppm) were added to a 250 mL flask and stirred to dissolve. 4.18 g (0.024 mol) of toluene-2,4-diisocyanate and 0.02 g of dibutyltin dilaurate were added, and the mixture was reacted at 60 °C for 3 h to obtain isocyanate-terminated polyethylene glycol prepolymer. 1.15 g (0.004 mol) of lithium bis(trifluoromethanesulfonyl)imide was added, and the mixture was stirred at room temperature for 12 h. Acetonitrile was removed by vacuum distillation to obtain an isocyanate-terminated polyether-lithium salt complex (approximately 43 g).

[0037] Preparation Example 4: Preparation of a fluorinated siloxane surfactant (isocyanate-terminated polydimethylsiloxane-perfluoropolyether-polyethylene glycol triblock copolymer) Add 20g of single-ended hydrogenated silicone oil (number average molecular weight 2000g / mol) to a 100mL flask. 0.010 mol) of 0.012 mol) of allyl-terminated perfluoropolyether (number average molecular weight 1500 g / mol) was added to 50 mL of freshly distilled toluene and 0.5 mL of isopropanol chloroplatinate solution (Pt concentration 20 ppm). The reaction was carried out at 80 °C under nitrogen protection for 4 h to obtain a diblock copolymer of polydimethylsiloxane-perfluoropolyether. 9.6 g (0.012 mol) of allyl-terminated polyethylene glycol (number average molecular weight 800 g / mol) was added, and the reaction was continued at 80 °C for 4 h to obtain a triblock copolymer of polydimethylsiloxane-perfluoropolyether-polyethylene glycol. 5 g (0.030 mol) of hexamethylene diisocyanate was added, and the reaction was continued at 80 °C for 2 h. Toluene and unreacted HDI were removed by vacuum distillation to obtain an isocyanate-terminated polydimethylsiloxane-perfluoropolyether-polyethylene glycol triblock copolymer (approximately 48 g). The product was confirmed by FT-IR. The characteristic absorption peak of NCO appears at this location. A characteristic absorption peak for the CF bond appears at this location. Appear at place Characteristic absorption peaks.

[0038] Table 1. Raw material composition of coating liquids in Examples 1-6 (by parts by mass)

[0039] The preparation method of the coating liquid includes the following steps: The hydroxyl-terminated hyperbranched polyurethane prepolymer was added to a mixed solvent and stirred at room temperature for 30 min until completely dissolved. The moisture content of the system was measured using a Karl Fischer moisture analyzer (confirmed to be <500 ppm). An isocyanate derivative containing UPy groups and a polyether-lithium salt complex with isocyanate-terminated groups were added and stirred for 2 h under nitrogen protection at 50℃±5℃. This allowed the NCO in UPy-NCO and PEO-LiTFSI-NCO to undergo an urethane reaction with the terminal hydroxyl groups of the hyperbranched prepolymer, achieving end grafting. After cooling to room temperature, a fluorosiloxane surfactant, a light stabilizer, an ultraviolet absorber, and a catalyst were added and stirred until homogeneous. The curing agent was added just before coating, and the mixture was stirred rapidly for 5 min. After standing for 5 min to 10 min to remove bubbles, the coating solution was obtained.

[0040] The method for applying a screen protector includes the following steps: The substrate is made of ABA three-layer co-extruded biaxially oriented PET (total thickness 50μm, A layer pure PET thickness 0.8μm, B layer with 1.5wt% polythiophene antistatic agent). The surface of A layer is corona treated (power density 40W·min / m², electrode spacing 2mm, surface tension 52mN / m). After treatment, it enters the coating station within 8s. At the entrance of the transverse stretching section, the coating liquid is applied to the corona-treated A layer surface through the grooved coating head; it enters the transverse stretching section and is stretched laterally; it is then heat-cured by passing through a three-stage drying tunnel at 100℃ / 30s, 120℃ / 30s, and 140℃ / 30s in sequence, and after cooling to 45℃, a light release force fluorine release film (release force 4g / inch) is laminated, and the film is wound up. The master roll is placed in a 50℃ drying oven for 48 hours and then cut to obtain the screen protection film sample.

[0041] Table 2. Process parameters and pressure-sensitive adhesive layer thickness for Examples 1-6

[0042] Comparative Example 1 The difference from Example 1 is that an equal mass fraction of linear polyurethane (number average molecular weight 12000 g / mol, terminal hydroxyl functionality 2, prepared by reacting polybutylene adipate diol PBA-2000 with IPDI) is used instead of the terminal hydroxyl hyperbranched polyurethane prepolymer.

[0043] Comparative Example 2 The difference from Example 1 is that no isocyanate derivative with UPy groups is added, and the amount of hydroxyl-terminated hyperbranched polyurethane prepolymer is adjusted to 120 parts.

[0044] Comparative Example 3 The difference from Example 1 is that an equal part by mass of poly(3,4-ethylenedioxythiophene) (PEDOT, CAS No. 126213-51-2, added in the form of PEDOT:PSS aqueous dispersion, solid content 1.3wt%) was used in place of the terminal isocyanate polyether-lithium salt complex by physical blending.

[0045] Comparative Example 4 The difference from Example 1 is that an equal part by mass of a non-reactive fluorinated surfactant (containing no NCO group, 3M's FC-4430) is used instead of a fluorinated siloxane surfactant.

[0046] Comparative Example 5 The difference from Example 1 is that no fluorinated siloxane surfactant is added.

[0047] Comparative Example 6 The difference from Example 1 is that both layer A and layer B of the substrate contain a polythiophene antistatic agent (1.5 wt%).

[0048] Performance testing 1. Surface Resistance: Referring to ASTM D257, "Standard Test Method for DC Resistance or Conductivity of Insulating Materials", the protective film sample (100mm × 100mm) was placed in an environment of 23℃±2℃ and 50%±5% relative humidity for 24 hours to equilibrate. After peeling off the release film, the surface resistance of the air surface and the adhesive surface was measured separately using a high resistance meter (Keithley 6517A). The test voltage was 100V and the electrode spacing was 10mm. The geometric mean of the measurements at 5 different locations was taken. The surface resistance after aging was tested by placing the sample in an environment of 60℃ / 90%RH for 120 hours, then removing it and equilibrating it in an environment of 23℃±2℃ and 50%±5% relative humidity for 24 hours before testing it in the same way.

[0049] 2. Water Contact Angle: Referring to GB / T 30447-2013, the water contact angle of the air surface of the protective film was measured using a contact angle measuring instrument at an environment of 23℃±2℃. 2μL of deionized water was added each time, and the contact angle value was read after the droplet stabilized (30s). The arithmetic mean of the measurements at 5 different locations was taken. Wiping Durability Test: A lint-free cloth (polyester fiber, 120g / m²) was used to repeatedly wipe the sample surface at a speed of 10cm / s under the pressure of a 500g weight. The wiping frequency was 60 times / min. The water contact angle was measured after each certain number of wiping cycles.

[0050] 3. Exhaust time: Cut the protective film sample to A4 size (210mm×297mm). After peeling off the release film, place the adhesive side of the protective film at a 45° angle to one end of a clean glass plate and press it down evenly at a speed of about 50mm / s. Use a high-speed camera to record the time (s) required from the start of bonding until the bonding interface is completely free of bubbles (bubble area <1mm²). Take the arithmetic mean of 3 samples.

[0051] 4. Adhesion (180° peel): Referring to FINAT FTM1 "Test Method for 180° Peel Strength of Pressure Sensitive Adhesive Tape", the protective film sample was cut into 25mm×300mm size. After peeling off the release film, it was adhered to the surface of a clean glass plate and rolled back and forth once with a 2kg rubber roller at a speed of 300mm / min. The adhered sample was placed in a 60℃ / 90%RH environment for 120h for aging and then removed. After peeling, the surface of the glass plate was observed with an optical microscope to see if there was any residual adhesive or other contaminants.

[0052] 5. Self-repair efficiency Using an atomic force microscope, a scratch approximately 50 μm wide was created on the air surface of the protective film using a diamond needle tip (radius of curvature approximately 50 nm) (applied force 50 μN, scanning speed 1 μm / s); the scratch width was measured using an optical microscope. After placing the sample in an environment of 25℃±2℃ for 30 minutes, the scratch width was measured again. Self-repair efficiency is calculated using the following formula: Self-repair efficiency (%) = ×100%; take the arithmetic mean of the three scratches.

[0053] Table 3. Test results of surface resistivity, water contact angle, and exhaust time for the examples and comparative examples.

[0054] Table 4. Test results of adhesion and self-healing efficiency of the examples and comparative examples.

[0055] As shown in Tables 3 and 4, Examples 1 to 6 achieve a synergistic unity of pressure-sensitive adhesive layers in terms of antistatic properties, self-healing, hydrophobicity and antifouling, low adhesion and venting, and long-term weather resistance. Compared with Example 1, Comparative Example 1 showed a significantly increased adhesion, a greatly prolonged venting time, and a significant decrease in self-healing efficiency, with slight residue appearing after aging. This indicates that the hyperbranched topology can endow the pressure-sensitive adhesive with low adhesion, rapid venting, and good self-healing efficiency. Comparative Example 2 almost completely lost its self-healing efficiency, while its adhesion and venting performance showed no significant change, indicating that the UPy quadruple hydrogen bonds directly affect the self-healing effect but have no negative impact on other properties. Comparative Example 3 had a high initial surface resistance, which increased sharply after aging, resulting in complete failure of its antistatic properties. Furthermore, the adhesion increased significantly after aging, and significant residue appeared, indicating that the physically blended antistatic agent migrated and precipitated during the humid heat aging process, not only failing itself but also causing contamination. The pressure-sensitive adhesive interface leads to deterioration of adhesion performance; the initial water contact angle of Comparative Example 4 is comparable to that of Example 1, but the water contact angle decreases after 200 wipings with a lint-free cloth, possibly because the non-reactive surfactant is only physically adsorbed and fixed on the adhesive surface, and is gradually removed during wiping; the water contact angle of Comparative Example 5 is only 81.3°, and it does not have hydrophobic and antifouling functions, indicating that the fluorosiloxane surfactant is an independent functional unit to achieve hydrophobic function; the adhesion of Comparative Example 6 increases, and further increases to 8.6 gf / inch after aging, and obvious residue appears, possibly because the antistatic agent in the substrate B layer migrates to the pressure-sensitive adhesive layer interface in the absence of pure PET isolation in the A layer, interfering with the adhesion performance of the pressure-sensitive adhesive and causing residue pollution.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] 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 descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that 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 for those skilled in the art.

Claims

1. A fast-venting, weather-resistant, antistatic screen protector, characterized in that, It includes a polyester substrate layer and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is formed by thermosetting a coating liquid, and the coating liquid comprises the following raw material components in parts by weight: 100 parts of hydroxyl-terminated hyperbranched polyurethane prepolymer; 10 to 30 parts of isocyanate derivatives containing UPy groups; 8 to 25 parts of isocyanate-terminated polyether-lithium salt complex; 0.5 to 2 parts of fluorinated siloxane surfactant; 5 to 15 parts of curing agent; Light stabilizer 0.5 to 2 parts; 0.5 to 2 parts of ultraviolet absorber; Catalyst: 0.05 to 0.2 parts; Solvent: 180-280 parts.

2. The fast-venting, weather-resistant, antistatic screen protector as described in claim 1, characterized in that, The number-average molecular weight of the terminal hydroxyl hyperbranched polyurethane prepolymer is 8000 g / mol to 20000 g / mol, and the terminal hydroxyl functionality is 5 to 10.

3. The fast-venting, weather-resistant, antistatic screen protector as described in claim 1, characterized in that, The hydroxyl-terminated hyperbranched polyurethane prepolymer is prepared by a method comprising the following steps: a molten transesterification reaction of diethanolamine and dimethyl adipate under vacuum to obtain a hydroxyl-terminated hyperbranched polyester core; an addition reaction of the hydroxyl-terminated hyperbranched polyester core and isophorone diisocyanate in the presence of a catalyst to obtain the hydroxyl-terminated hyperbranched polyurethane prepolymer; wherein the molar ratio of diethanolamine to dimethyl adipate is 5:

3.

4. The fast-venting, weather-resistant, antistatic screen protector as described in claim 1, characterized in that, The isocyanate derivative containing the UPy group is 6-methyl-2-(6-isocyanate-hexyl)ureido-4[1H]-pyrimidinone.

5. The fast-venting, weather-resistant, antistatic screen protector as described in claim 1, characterized in that, The terminal isocyanate-based polyether-lithium salt complex is a coordination complex of terminal isocyanate-based polyethylene glycol and bis(trifluoromethanesulfonyl)imide, wherein the number-average molecular weight of the polyethylene glycol is 2000 g / mol to 5000 g / mol, and the molar ratio of lithium ions to polyethylene glycol repeating units is 1:(6~12).

6. The fast-venting, weather-resistant, antistatic screen protector as described in claim 1, characterized in that, The fluorinated siloxane surfactant is a triblock copolymer of isocyanate-terminated polydimethylsiloxane-perfluoropolyether-polyethylene glycol.

7. The fast-venting, weather-resistant, antistatic screen protector as described in claim 6, characterized in that, The fluorinated siloxane surfactant is prepared by a method comprising the following steps: hydrosilylation of a single-ended hydrogenated silicone oil with an allyl-terminated perfluoropolyether in the presence of a platinum catalyst to obtain a diblock copolymer of polydimethylsiloxane and perfluoropolyether; further hydrosilylation of the diblock copolymer with an allyl-terminated polyethylene glycol to obtain a triblock copolymer of polydimethylsiloxane, perfluoropolyether, and polyethylene glycol; and reaction of the triblock copolymer with hexamethylene diisocyanate to obtain the fluorinated siloxane surfactant.

8. The fast-venting, weather-resistant, antistatic screen protector as described in claim 1, characterized in that, The curing agent is an aliphatic isocyanate curing agent, the light stabilizer is a hindered amine light stabilizer, the catalyst is an organotin catalyst, and the solvent is a mixed solvent of methyl ethyl ketone and ethyl acetate.

9. A method for preparing a fast-venting, weather-resistant, antistatic screen protector as described in any one of claims 1 to 8, characterized in that, Includes the following steps: The hydroxyl-terminated hyperbranched polyurethane prepolymer was mixed evenly with a solvent, and then an isocyanate derivative containing UPy groups and an isocyanate-terminated polyether-lithium salt complex were added. The mixture was stirred at 50℃±5℃ for 1.5h~2.5h, cooled to room temperature, and then a fluorosiloxane surfactant, a light stabilizer, an ultraviolet absorber and a catalyst were added and stirred evenly to obtain a mixture. Add a curing agent to the mixture, stir until homogeneous and degas to obtain a coating liquid; The coating liquid is applied to the surface of the polyester substrate layer, and after biaxial stretching and thermosetting, a release film is laminated, wound up, and cured to obtain a screen protector film.

10. The method for preparing the rapid-venting, weather-resistant, antistatic screen protector as described in claim 9, characterized in that, The bidirectional stretching includes longitudinal stretching and transverse stretching. The stretching ratio of the longitudinal stretching is 3 to 3.5 times, and the stretching ratio of the transverse stretching is 3 to 3.5 times. The transverse stretching is carried out at 80°C to 100°C.

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