Hard coat film and method for producing the same

Abstract

This application provides a hard coating film and its preparation method, relating to the field of optical film technology. The hard coating film includes a substrate layer and a hard coating layer disposed on the surface of the substrate layer; the hard coating layer includes a cured matrix and hydrophobically modified inorganic nanoparticles dispersed in the cured matrix. The cured matrix includes a cross-linked and cured polar resin and a polar monomer, with at least some of the hydrophobically modified inorganic nanoparticles protruding from the surface of the hard coating layer to form multiple protrusions; wherein, the water contact angle of the hard coating film surface is >90°, and the surface roughness is 0.2μm~0.6μm. By employing hydrophobically modified inorganic nanoparticles, cross-linked and cured polar resin, and polar monomers in the hard coating layer, and by controlling the surface roughness and water contact angle of the hard coating film, a synergistic improvement in optical transparency, scratch resistance, long-term anti-adhesion properties, and anti-adhesion properties under high temperature and high humidity environments is achieved.

Description

Technical Field

[0001] This application relates to the field of optical film technology, and in particular to a hard coating film and its preparation method. Background Technology

[0002] Current image display devices such as liquid crystal displays (LCDs) and OLEDs typically undergo functional treatments on their surfaces, including polarizers, screen protectors, cover plates, and touchscreens. These functional treatments include scratch-resistant hard coatings, anti-glare films to prevent external glare, anti-reflective films to reduce screen reflections, and anti-fouling films to improve fingerprint wiping. These functional hard coatings are usually produced continuously in a roll-to-roll manner. When the functional hard coatings are wound in this manner, if the surface of the hard coating is too smooth, the hard coating and the base film, as well as the hard coatings themselves, can adhere due to "mirror-like" adhesion. This phenomenon becomes more pronounced with higher winding tension. Over time, the adhered hard coatings can cause localized deformation during unwinding, potentially leading to damage or tearing.

[0003] To address the aforementioned issues, existing research has explored adding inorganic microparticles to the coating layer of hard coatings to create micro-protrusions on the surface, which can alleviate adhesion between hard coatings to some extent. However, the hard coatings obtained using this method still have the following drawbacks: (1) optical performance needs improvement; (2) scratches are easily generated on the interlayer film surfaces during winding; and (3) the long-term anti-adhesion effect and the anti-adhesion effect under high temperature and high humidity conditions are poor. Summary of the Invention

[0004] Based on the above-mentioned technical problems, the purpose of this application is to propose a hard coating film and its preparation method, so as to improve the optical performance of the hard coating film, reduce the adhesion between hard coating films and the scratches between the winding layers, and at the same time improve the anti-adhesion and long-term anti-adhesion properties of the roll hard coating film during transportation and storage in high temperature and high humidity environments. In a first aspect, embodiments of this application provide a hard coating film, including a substrate layer and a hard coating layer disposed on the surface of the substrate layer; the hard coating layer includes a cured matrix and hydrophobically modified inorganic nanoparticles dispersed in the cured matrix, the cured matrix includes a cross-linked cured polar resin and a polar monomer, at least some of the hydrophobically modified inorganic nanoparticles protrude from the surface of the hard coating layer to form multiple protrusions; wherein, the water contact angle of the surface of the hard coating film is >90°, and the surface roughness is 0.2μm~0.6μm.

[0005] In the above technical solution, this application employs cross-linking and curing of polar resin and polar monomers in the hard coating, and sets hydrophobically modified inorganic nanoparticles protruding from the surface of the hard coating to form multiple protrusions. Combined with controlling the surface roughness of the hard coating film to 0.2μm~0.6μm and the water contact angle >90°, a synergistic improvement in optical transparency, scratch resistance, long-term anti-adhesion, and anti-adhesion under high temperature and high humidity environments is achieved. The core technical effects are as follows: (1) This application provides stable and effective physical isolation between layers by using micro-protrusion structures protruding from the surface of the hard coating, combined with surface roughness control of 0.2μm~0.6μm; at the same time, hydrophobic modified inorganic nanoparticles enriched on the coating surface construct a low surface energy hydrophobic interface with a water contact angle >90°, further reducing the interlayer interface adhesion force and forming an anti-adhesion synergistic effect with the micro-protrusion structure.

[0006] Furthermore, since the surface roughness of the hard coating is largely determined by the protrusions, and the hydrophobic low surface energy characteristics (water contact angle) are determined by the hydrophobic modified inorganic nanoparticles enriched on the coating surface, both of which rely on the hydrophobic modified inorganic nanoparticles, only a small amount of hydrophobic modified inorganic nanoparticles need to be added to form a micro-protrusion structure and a low surface energy hydrophobic interface on the coating surface that meet the requirements for anti-adhesion. This eliminates the need for high filler content and significantly reduces the negative impact of high filler content on other properties of the coating.

[0007] (2) Since hydrophobically modified inorganic nanoparticles are nonpolar or low polar, they are not easy to agglomerate and can achieve excellent monodispersity in the solidified matrix. At the same time, combined with the aforementioned low filler content design, the impact on optical performance can be effectively reduced.

[0008] Therefore, by combining a small amount of uniformly dispersed hydrophobic modified inorganic nanoparticles, the hard coating film achieves excellent anti-blocking performance while maintaining high light transmittance and low haze. The transmittance of the hard coating film in the visible light band is not less than 90%, and the haze is not higher than 0.8%.

[0009] (3) Compared with hydrophilic particles, hydrophobic modified inorganic nanoparticles have lower surface energy, which gives the protruding structure better lubrication and sliding properties. During the relative sliding process between layers of the hard coating film during winding and unwinding, the interlayer friction coefficient can be significantly reduced (dynamic friction coefficient is less than 0.3), and the film surface between layers is less likely to be scratched during the winding process.

[0010] (4) Compared with hydrophilic particles, hydrophobic modified inorganic nanoparticles are less likely to absorb water, which reduces the risk of failure of hard coating film due to moisture and sticking. They can maintain good anti-sticking properties during long-term transportation and storage as well as in high temperature and high humidity environments. In one possible implementation, the hydrophobically modified inorganic nanoparticles include at least one of hydrophobically modified silica nanoparticles, hydrophobically modified alumina nanoparticles, or hydrophobically modified titanium dioxide nanoparticles. In the above technical solution, silica, alumina and titanium dioxide are all commonly used inorganic nanofillers in the field. They are easy to modify hydrophobically and have excellent dispersibility in the cured matrix after modification, which is beneficial to further improve the anti-blocking and light transmittance of the hard coating film.

[0011] In one possible implementation, the surface of hydrophobically modified inorganic nanoparticles is free of grafted functional groups containing carbon-carbon double bonds.

[0012] In the above technical solution, the surface of the hydrophobically modified inorganic nanoparticles does not contain carbon-carbon double bonds, such as acryloyloxy or methacryloyloxy. They do not need to participate in the photocuring crosslinking reaction during the photocuring crosslinking process, which is conducive to further promoting the migration of hydrophobically modified nanoparticles to the coating surface. This is beneficial to further reduce the amount of hydrophobically modified nanoparticles used, thereby improving the optical transparency of the hard coating film.

[0013] In one possible implementation, the median particle size D50 of the hydrophobically modified inorganic nanoparticles is 50 nm to 150 nm. In the above technical solution, the median particle size D50 is within the above range, which is beneficial to achieve a surface roughness of 0.2μm~0.6μm, while maintaining high anti-blocking properties, stable high light transmittance and low haze.

[0014] In one possible implementation, the thickness of the hard coating is 3μm to 5μm. In the above technical solution, the thickness of the hard coating is within a suitable range, which can match the particle size of the hydrophobic modified inorganic nanoparticles, providing them with sufficient intercalation space, stably forming a raised structure, controlling the surface roughness of the hard coating film to 0.2μm~0.6μm, and also allowing the surface particles to fully expose hydrophobic groups, stably achieving a surface water contact angle of >85°, thus achieving a good anti-adhesion effect with a low particle dosage.

[0015] In one possible implementation, the polar resin includes at least one of the cured resins containing hydroxyl, amino, or carboxyl groups; and / or, the polar monomer includes at least one of the cured monomers containing hydroxyl, amino, or carboxyl groups. In the above technical solution, the polar resin and polar monomer can form a large surface energy difference with the hydrophobic modified inorganic nanoparticles, providing sufficient thermodynamic driving force for the migration of particles to the gas-solid interface of the coating. This allows the particles to spontaneously accumulate on the surface during the drying and curing process, thereby enabling the hydrophobic modified inorganic nanoparticles to achieve a surface roughness of 0.2μm~0.6μm with a relatively small dosage range, while fully exposing the hydrophobic groups and stably achieving a surface water contact angle of >85°.

[0016] Optionally, the polar resin includes at least one of polyurethane acrylate, epoxy acrylate, or polyester acrylate.

[0017] Optionally, the polar monomer includes at least one of pentaerythritol triacrylate, hydroxyhexyl acrylate, hydroxyhexyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, or glyceryl monoacrylate.

[0018] In one possible implementation, the total mass ratio of the polar resin and polar monomer to the mass ratio of the hydrophobically modified inorganic nanoparticles is (30~80):(1.5~5.0).

[0019] In the above technical solution, the amount of hydrophobic modified inorganic nanoparticles used is relatively small, which is significantly different from the total amount of polar resin and polar monomer. This is beneficial to maximizing the surface energy difference between the cured matrix and the hydrophobic modified inorganic nanoparticles, while further improving the optical transparency of the hard coating film.

[0020] In one possible implementation, the coefficient of kinetic friction between the hard coating films is less than 0.3. In the above technical solution, the dynamic friction coefficient is less than 0.3, which corresponds to low interlayer sliding resistance and can significantly reduce the risk of scratches and adhesion between winding layers.

[0021] Secondly, embodiments of this application provide a method for preparing a hard coating film according to the first aspect, comprising the following steps: A hard coating liquid is obtained by mixing the matrix to be cured, hydrophobically modified inorganic nanoparticles, and a first solvent; wherein the matrix to be cured includes a polar resin and a polar monomer. The hard coating liquid is applied to the surface of the substrate layer, and then dried and cured with ultraviolet light in sequence to cross-link and cure the matrix to be cured to form a cured matrix. Hydrophobic modified inorganic nanoparticles are dispersed in the cured matrix to form a hard coating layer, thus obtaining a hard coating film.

[0022] In the above technical solution, this application employs a matrix to be cured and hydrophobically modified inorganic nanoparticles. Utilizing the difference in polarity / surface energy between the hydrophobically modified nanoparticles and the polar resin and polar monomers, during the drying process, the particles spontaneously migrate and accumulate at the coating's gas-solid interface. Furthermore, during ultraviolet curing, because the coating surface cures first, the hydrophobically modified nanoparticles near the coating surface are anchored to the coating surface, forming protrusions. Meanwhile, the curing process within the coating is slower and has lower viscosity; during curing, the particles continue to migrate towards the coating surface, eventually accumulating into protrusions on the coating surface upon final curing. Therefore, excellent anti-blocking effects can be achieved with a relatively small amount of particles, while maintaining high transmittance and low haze in the coating.

[0023] In one possible implementation, the polar resin includes at least one of the cured resins containing hydroxyl, amino, or carboxyl groups, and the polar monomer includes at least one of the cured monomers containing hydroxyl, amino, or carboxyl groups. Based on the total mass of the matrix to be cured, the total mass ratio of polar resin and polar monomer is 30wt~80wt.

[0024] In the above technical solution, the proportion of polar resin and polar resin within the above range is beneficial to maintain the overall strong polarity of the matrix to be cured, increase the surface energy difference between it and the hydrophobic modified inorganic nanoparticles, provide sufficient driving force for the spontaneous migration of hydrophobic modified inorganic nanoparticles to the coating surface, thereby further improving the optical transparency and anti-blocking effect of the hard coating film.

[0025] In one possible implementation, the mass percentage of hydrophobically modified inorganic nanoparticles is 1.5wt% to 5.0wt% based on the total mass of the matrix to be cured.

[0026] In the above technical solution, the mass ratio of hydrophobic modified inorganic nanoparticles within the above range can form a sufficient surface energy difference with the polar matrix to be cured, providing sufficient driving force for particle migration to the surface. The smaller amount can further improve the dispersion uniformity in the matrix to be cured and further improve the optical transparency of the hard coating film.

[0027] In one possible implementation, the mixing step includes: dispersing hydrophobically modified inorganic nanoparticles in a second solvent to obtain a dispersion; and mixing the dispersion, a polar matrix to be cured, and a first solvent to obtain a hard coating liquid.

[0028] In the above technical solution, by first dispersing the hydrophobically modified inorganic nanoparticles in the second solvent, it is beneficial to reduce the influence of polarity mismatch between the polar matrix to be cured and the hydrophobically modified inorganic nanoparticles, improve the dispersion uniformity of the hydrophobically modified inorganic nanoparticles in the hard coating liquid, thereby further improving the distribution uniformity of the protrusion structure in the hard coating layer, further reducing the amount of hydrophobically modified inorganic nanoparticles used, and thus further improving the anti-blocking effect and transparency of the hard coating film.

[0029] Optionally, the polarity of the second solvent is lower than that of the first solvent.

[0030] In one possible implementation, the preparation method of hydrophobically modified inorganic nanoparticles includes: Inorganic nanoparticles are surface-grafted and modified using silane coupling agents or fluorosilane coupling agents; wherein the inorganic nanoparticles include at least one of silicon dioxide, aluminum oxide or titanium oxide, and the mass ratio of silane coupling agent or fluorosilane coupling agent to inorganic nanoparticles is (0.2~0.6):1.

[0031] In the above technical solution, a hydrophobic modified layer can be formed on the surface of inorganic nanoparticles by covalent grafting with silane coupling agents or fluorosilane coupling agents, thereby obtaining hydrophobic modified inorganic nanoparticles. The modification method is simple, reliable, and highly stable. Attached Figure Description To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a process flow diagram of a method for preparing a hard coating film according to an embodiment of this application.

[0033] Figure 2 These are photographs of the appearance of the hard coating films in Example 1 and Comparative Example 1 of this application after a 72-hour anti-blocking test at room temperature.

[0034] Figure 3 These are photographs showing the appearance of the hard coating film in Example 1 and Comparative Example 1 of this application after the finished product is wound up. Detailed Implementation

[0035] The embodiments of the hard coating film and its preparation method described below are disclosed in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of essentially the same structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0036] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0037] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0038] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0039] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0040] Existing research has shown that adding inorganic microparticles to the coating of hard coatings can create micro-protrusions on the surface of the hard coating, which can alleviate the adhesion between hard coatings to some extent. However, the hard coatings obtained by this method still have the following defects: (1) the optical performance needs to be improved; (2) the film surface between layers is easily scratched during the winding process; and (3) the anti-adhesion effect is poor in long-term and high-temperature and high-humidity environments. The applicant's research revealed that the possible reasons are as follows: Existing technologies typically use hydrophilic inorganic microparticles, which have high surface polarity and are prone to forming hydrogen bonds, leading to agglomeration and difficulty in dispersion. Even if dispersed, these particles are prone to agglomeration during subsequent processing, and the increased particle size of the agglomerated microparticles impairs optical performance. Furthermore, the high surface polarity and high surface energy of hydrophilic particles result in abrasiveness and poor sliding properties, which can easily scratch the interlayer film surface during winding. Moreover, because hydrophilic microparticles contain a large number of hydrophilic groups (such as hydroxyl groups), they are prone to absorbing water during subsequent transportation and storage, especially under prolonged and / or high temperature and humidity conditions. This can cause the anti-adhesion hard coating to become damp and sticky, leading to its failure.

[0041] Based on this, this application provides a hard coating film, including a substrate layer and a hard coating layer disposed on the surface of the substrate layer; the hard coating layer includes a cured matrix and hydrophobically modified inorganic nanoparticles dispersed in the cured matrix, the cured matrix includes a cross-linked cured polar resin and a polar monomer, at least some of the hydrophobically modified inorganic nanoparticles protrude from the surface of the hard coating layer to form multiple protrusions; wherein, the water contact angle of the surface of the hard coating film is >90°, and the surface roughness is 0.2μm~0.6μm.

[0042] In this application, "cured matrix" refers to a continuous phase of polar polymer with a three-dimensional crosslinked network, formed by crosslinking and curing polar resins, polar monomers, and possibly other UV resins. "Hydrophobically modified inorganic nanoparticles" refers to nanoparticles with an inorganic nanoparticle core and surface modified by covalently grafting hydrophobic groups. Understandably, hydrophobically modified inorganic nanoparticles are typically nonpolar or low-polar, exhibiting a significant surface energy difference with the cured matrix.

[0043] In this application, "at least some hydrophobically modified inorganic nanoparticles protrude from the surface of the hard coating to form multiple protrusions" refers to a structure formed by individual hydrophobically modified inorganic nanoparticles being partially embedded and fixed inside the hard coating, and partially protruding from the surface of the hard coating. The number and height of the protrusions can affect the water contact angle and surface roughness of the hard coating surface. "At least some" means that all hydrophobically modified inorganic nanoparticles can form protrusions, or only some of the hydrophobically modified inorganic nanoparticles can form protrusions while the other part is dispersed inside the hard coating. "Water contact angle of the hard coating surface" is a physical quantity used to characterize the hydrophobicity of the hard coating surface; a larger value indicates stronger surface hydrophobicity, and it can be measured using a water contact angle meter. "Surface roughness" in this application refers to the ten-point average roughness Rz, used to characterize the microscopic unevenness of the hard coating surface, and can be measured using a profilometer.

[0044] In this application, by using polar resin and polar monomers to cure in a hard coating and setting hydrophobically modified inorganic nanoparticles protruding from the surface of the hard coating to form multiple protrusions, combined with controlling the surface roughness of the hard coating film to 0.2μm~0.6μm and the water contact angle >90°, a synergistic improvement in anti-adhesion performance, optical transparency, scratch resistance and long-term environmental stability is achieved. The core technical effects are as follows: (1) This application provides stable and effective physical isolation between layers by using micro-protrusion structures protruding from the surface of the hard coating, combined with surface roughness control of 0.2μm~0.6μm; at the same time, hydrophobic modified inorganic nanoparticles enriched on the coating surface construct a low surface energy hydrophobic interface with a water contact angle >90°, further reducing the interlayer interface adhesion force and forming an anti-adhesion synergistic effect with the micro-protrusion structure.

[0045] Furthermore, since the surface roughness of the hard coating is largely determined by the protrusions, and the hydrophobic low surface energy characteristics (water contact angle) are determined by the hydrophobic modified inorganic nanoparticles enriched on the coating surface, both of which rely on the hydrophobic modified inorganic nanoparticles, only a small amount of hydrophobic modified inorganic nanoparticles need to be added to form a micro-protrusion structure and a low surface energy hydrophobic interface on the coating surface that meet the requirements for anti-adhesion. This eliminates the need for high filler content and significantly reduces the negative impact of high filler content on other properties of the coating.

[0046] (2) Since hydrophobically modified inorganic nanoparticles are nonpolar or low polar, they are not easy to agglomerate and can achieve excellent monodispersity in the solidified matrix. At the same time, combined with the aforementioned low filler content design, the impact on optical performance can be effectively reduced.

[0047] Therefore, by combining a small amount of uniformly dispersed hydrophobic modified inorganic nanoparticles, the hard coating film achieves excellent anti-blocking performance while maintaining high light transmittance and low haze. The transmittance of the hard coating film in the visible light band is not less than 90%, and the haze is not higher than 0.8%.

[0048] (3) Compared with hydrophilic particles, hydrophobic modified inorganic nanoparticles have lower surface energy, which gives the protruding structure better lubrication and sliding properties. During the relative sliding process between layers of the hard coating film during winding and unwinding, the interlayer friction coefficient can be significantly reduced (dynamic friction coefficient is less than 0.3), and the film surface between layers is less likely to be scratched during the winding process.

[0049] (4) Compared with hydrophilic particles, hydrophobic modified inorganic nanoparticles are less likely to absorb water, which reduces the risk of failure of hard coating film due to moisture and sticking. They can maintain good anti-sticking properties during long-term transportation and storage as well as in high temperature and high humidity environments. As an example, the water contact angle of the hard coating surface is any one value or any two values ​​between any two points from 90.4°, 90.8°, 91.2°, 91.4°, 92.2°, 96.8°, and 100°; the surface roughness is any one value or any two values ​​between any two points from 0.2μm, 0.3μm, 0.4μm, 0.5μm, and 0.6μm.

[0050] In some embodiments, the coefficient of kinetic friction between hard coatings is less than 0.3.

[0051] In this application, the coefficient of kinetic friction refers to the interlayer kinetic friction coefficient when the hard coating film comes into contact with the hard coating layer of the hard coating film and relative sliding occurs. It can be obtained by testing with a coefficient of friction meter. As an example, the coefficient of kinetic friction between the hard coating films can be 0.29, 0.25, 0.23, 0.20, 0.18, 0.15, 0.10, etc.

[0052] The following details the hard coating film and its preparation method in this application.

[0053] Figure 1 For a process flow diagram of a method for preparing a hard coating film according to an embodiment of this application, please refer to [link / reference]. Figure 1 The preparation method includes the following steps: S1: Mix the matrix to be cured, hydrophobically modified inorganic nanoparticles and the first solvent to obtain a hard coating liquid; wherein, the matrix to be cured includes a polar resin and a polar monomer.

[0054] In some embodiments, the hydrophobically modified inorganic nanoparticles include at least one of hydrophobically modified silica nanoparticles, hydrophobically modified alumina nanoparticles, or hydrophobically modified titanium dioxide nanoparticles.

[0055] It is understood that the hydrophobically modified inorganic nanoparticles used in this application can be obtained directly from commercially available sources or prepared using conventional modification methods in the field, and this application does not make any specific limitations on this.

[0056] For example, a method for preparing hydrophobically modified inorganic nanoparticles includes: surface grafting modification of inorganic nanoparticles with a silane coupling agent or a fluorosilane coupling agent; wherein the inorganic nanoparticles include at least one of silicon dioxide, alumina, or titanium oxide, and the mass ratio of the silane coupling agent or fluorosilane coupling agent to the inorganic nanoparticles is (0.2~0.6):1. For example, the mass ratio of the silane coupling agent or fluorosilane coupling agent to the inorganic nanoparticles can be any one value or a range between any two values ​​from 0.2:1, 0.3:1, 0.4:1, 0.5:1:0.6:1.

[0057] Furthermore, the surface of the hydrophobically modified inorganic nanoparticles is not grafted with functional groups containing carbon-carbon double bonds. For example, grafting modification is not performed using propylene silane coupling agents and / or methacryloyloxysilane coupling agents.

[0058] Correspondingly, when using silane coupling agents or fluorosilane coupling agents to perform surface grafting modification on inorganic nanoparticles, the silane coupling agent may include at least one of dimethyldichlorosilane, propyltrimethoxysilane, propyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, hexadecyltrimethoxysilane, and dodecyltrimethoxysilane; the fluorosilane coupling agent may include at least one of trimethoxy(1H,1H,2H,2H-heptadecylfluorodecyl)silane, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and tridecafluorooctyltriethoxysilane.

[0059] In some embodiments, the median particle size D50 of the hydrophobically modified inorganic nanoparticles is 50 nm to 150 nm.

[0060] In this application, the median particle size D50 refers to the particle size value corresponding to the cumulative distribution percentage reaching 50% in the particle size distribution curve, which can be obtained by testing with a laser particle size analyzer.

[0061] As an example, the median particle size D50 of the hydrophobically modified inorganic nanoparticles is any one value or a range between any two values ​​of 50 nm, 60 nm, 80 nm, 100 nm, 120 nm, and 150 nm.

[0062] In some embodiments, the mass percentage of hydrophobic modified inorganic nanoparticles is 1.5 wt% to 5.0 wt% based on the total mass of the matrix to be cured. As an example, the mass percentage of hydrophobic modified inorganic nanoparticles in the matrix to be cured can be any one of 1.5 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, or a range between any two of these values.

[0063] In some embodiments, the polar resin includes at least one of the cured resins containing hydroxyl, amino, or carboxyl groups, and the polar monomer includes at least one of the cured monomers containing hydroxyl, amino, or carboxyl groups.

[0064] Optionally, the polar resin includes at least one of polyurethane acrylate (PUA), epoxy acrylate, or polyester acrylate, and the polar monomer includes at least one of pentaerythritol triacrylate, hydroxyhexyl acrylate, hydroxyhexyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, or glyceryl monoacrylate.

[0065] In some embodiments, the total mass percentage of polar resin and polar monomer is 30wt% to 80wt% based on the total mass of the matrix to be cured.

[0066] As an example, the total mass percentage of polar resin and polar monomer can be any one of 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, or a range between any two of these values.

[0067] In some embodiments, step S1 includes: dispersing hydrophobically modified inorganic nanoparticles in a second solvent to obtain a dispersion; and mixing the dispersion, the matrix to be cured, and a first solvent to obtain a hard coating liquid.

[0068] Furthermore, the polarity of the second solvent is lower than that of the first solvent. Understandably, in this application, a first solvent with higher polarity (polarity value > 3) is used to disperse the matrix to be reacted (including polar resin and polar monomer), and a second solvent with lower polarity (polarity value ≤ 3) is used to disperse the hydrophobic modified inorganic nanoparticles, which is beneficial to improving the dispersion uniformity and stability.

[0069] Optionally, the first solvent includes at least one of butanone and methyl isobutyl ketone; the second solvent includes at least one of toluene and isobutanol. Furthermore, the hydrophobic modified inorganic nanoparticles can be dispersed in the second solvent by ultrasonic dispersion, disc dispersion, or ball milling, and an appropriate amount of dispersant can also be added to the dispersion system.

[0070] Furthermore, the mass concentration of hydrophobically modified inorganic nanoparticles in the dispersion can be 10wt%~20wt%, for example, 10wt%, 15wt%, 20wt%, etc.

[0071] In some embodiments, the hard coating liquid further includes a photoinitiator to achieve curing of the hard coating layer. Optionally, the photoinitiator may be a pyrolytic initiator and / or a photosensitive initiator (hydrogen-abstraction type); wherein, the pyrolytic initiator may be one or more of 1-hydroxycyclohexylphenyl ketone (184), 2-hydroxy-methylphenylpropane-1-one (1173), 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone (907), benzoin dimethyl ether (651), and 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide (TPO). The photosensitive initiator (hydrogen-abstraction type) may be one or both of xylene ketone (BP) and 2-isopropylthioxanthone (ITX). Preferably, the photoinitiator is 1-hydroxycyclohexylphenyl ketone (184).

[0072] In some embodiments, the hard coating liquid also includes a leveling agent, which can reduce defects such as craters and pinholes in the cured hard coating. The leveling agent may be at least one of a fluorinated leveling agent, an organosiloxane leveling agent, and an organosilicone-modified acrylic leveling agent. Optionally, the leveling agent may be at least one of the following: Dainippon Ink & Chemicals' MEGAFACE F-444, F-445, F-470, F-477, F-479, F-553, F-554, and F-556; BYK Additive & Instruments' BYK-333, BYK-377, BYK-378, and BYK-UV 3505; Evonik's FLOW300, FLOW370, FLOW 425, RAD2200N, RAD2250N, and RAD2300N; and Deqian Chemicals' LEVASLIP835, LEVASLIP837, LEVASLIP867, and LEVASLIP879. Preferably, the leveling agent is BYK-UV 3505.

[0073] S2: Apply the hard coating liquid to the surface of the substrate layer, and then perform drying and UV curing treatment in sequence to cross-link and cure the matrix to be reacted to form a cured matrix. The hydrophobic modified inorganic nanoparticles are dispersed in the cured matrix to form a hard coating layer, thus obtaining a hard coating film.

[0074] Understandably, the hard coating liquid can be applied to one side or both sides of the substrate layer.

[0075] Understandably, the substrate layer in this application is a transparent film, which can be a plastic film with a total light transmittance of more than 85% in the wavelength range of 380nm to 780nm; or a plastic film with a total light transmittance of more than 90% in the wavelength range of 380nm to 780nm. Specifically, it can be one of the following: polyethylene terephthalate film (PET), colorless transparent polyimide film (CPI), norbornene film (COP), cellulose triacetate film (TAC), polyethylene naphthalate film (PEN), polycarbonate film (PC), polymethyl methacrylate film (PMMA), acrylonitrile (A)-butadiene (B)-styrene (S) terpolymer (ABS), ABS and PET composite film, PC and PMMA composite film, and polyetheretherketone film (PEEK). Preferably, the substrate layer is one of polyethylene terephthalate (PET), colorless transparent polyimide (CPI), norbornene (COP), and cellulose triacetate (TAC). Optionally, the thickness of the substrate layer can be 20 μm to 250 μm, such as 20 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, etc.

[0076] The coating method can be slit coating, microgravure coating, doctor blade coating, Mayer bar coating, roller coating, and scraper coating, etc., and this application does not make specific limitations on it.

[0077] In some embodiments, the drying and UV curing steps include: drying at 80°C to 100°C for 1 to 3 minutes, followed by UV curing at a light dose of 300 mJ / cm². 2 ~1000mj / cm 2 (Optional: 400mj / cm) 2 ~600mJ / cm 2 Under the condition of ultraviolet irradiation.

[0078] In some embodiments, the thickness of the hard coating is 3 μm to 5 μm. As an example, the thickness of the hard coating is any one value or a range between any two values ​​of 3 μm, 3.5 μm, 4 μm, 4.5 μm, and 5 μm.

[0079] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0080] Example 1 This embodiment provides a hard coating film, including a substrate layer and a hard coating layer disposed on the surface of the substrate layer. The hard coating layer includes a cured matrix and hydrophobically modified inorganic nanoparticles dispersed in the cured matrix.

[0081] The hydrophobically modified inorganic nanoparticles are silane-modified silica nanoparticles with a median particle size (D50) of 102 nm. The cured matrix consists of a cross-linked and cured polar resin and a polar monomer. The polar resin is a hydroxyl-containing bifunctional polyurethane acrylate, and the polar monomer is pentaerythritol triacrylate. The total mass ratio of the polar resin and polar monomer to the hydrophobically modified inorganic nanoparticles is 43.6:2.42; the thickness of the hard coating is 4.26 μm.

[0082] The preparation method of the hard coating film in Example 1 includes the following steps: (1) Take 2.25g of Dispers 685 wetting and dispersing agent and add it to 85g of toluene. After stirring for 10min, add 15g of Evonik hydrophobic silica powder Aerosil R974. After dispersing for 3.0h using an ultrasonic oscillator, the secondary particle size is measured to be 102nm, and a dispersion-A containing silane-modified silica nanoparticles is obtained.

[0083] (2) By weight, 20.3 parts of high-functional group PUA (SHIKOH 7610B, 9-functional PUA), 9.2 parts of hydroxyl-containing polar resin (Kunshan Castel U-Cure 93721, bifunctional PUA), 6.5 parts of hydroxyl-containing polar monomer (Changxing Chemical EM235, pentaerythritol triacrylate PET3A), 5.8 parts of dispersion-A, 1.86 parts of photoinitiator (IGM Omnirad184), 28.12 parts of solvent-1 (MEK), 28.12 parts of solvent-2 (MIBK), and 0.1 parts of leveling agent (BYK-UV 3505) were mixed and stirred for 30 minutes to obtain a hard coating liquid.

[0084] (3) The above hard coating liquid was coated onto a substrate layer (Toray U48, PET) with a thickness of 100 μm, dried at 90°C for 2 min, and then subjected to light dose of 500 mJ / cm. 2 A hard coating is obtained by irradiating the product with ultraviolet light from a high-pressure mercury lamp.

[0085] Example 2 This embodiment provides a hard coating film, which differs from Embodiment 1 in that: the total mass ratio of polar resin and polar monomer to the mass ratio of hydrophobically modified inorganic nanoparticles is 43.6:1.58; and the thickness of the hard coating is 4.11 μm.

[0086] The difference between its preparation method and that of Example 1 is that 3.8 parts of dispersion-A are added in step (2).

[0087] Example 3 This embodiment provides a hard coating film, which differs from Embodiment 1 in that: the total mass ratio of polar resin and polar monomer to the mass ratio of hydrophobically modified inorganic nanoparticles is 43.6:4.79; and the thickness of the hard coating is 4.33 μm.

[0088] The difference between its preparation method and that of Example 1 is that 11.5 parts of dispersion-A are added in step (2).

[0089] Example 4 This embodiment provides a hard coating film, which differs from Embodiment 1 in that: the hydrophobically modified inorganic nanoparticles are silane-modified silica nanoparticles with a median particle size D50 of 75 nm; and the thickness of the hard coating is 4.24 μm.

[0090] The preparation method differs from that in Example 1 in that: Step (1) includes: adding 2.25g of Dispers 685 wetting and dispersing agent to 85g of toluene, stirring for 10min, adding 15g of Evonik hydrophobic silica powder Aerosil R974, dispersing for 5.0h using an ultrasonic oscillator, and measuring the secondary particle size to be 75nm to obtain a dispersion-B containing silane-modified silica nanoparticles.

[0091] Add 5.8 parts of dispersion-B in step (2).

[0092] Example 5 This embodiment provides a hard coating film, which differs from Embodiment 1 in that: the hydrophobically modified inorganic nanoparticles are silane-modified silica nanoparticles with a median particle size D50 of 135 nm; and the thickness of the hard coating is 4.35 μm.

[0093] The preparation method differs from that in Example 1 in that: Step (1) includes: adding 2.25g of Dispers 685 wetting and dispersing agent to 85g of toluene, stirring for 10min, adding 15g of Evonik hydrophobic silica powder Aerosil R974, dispersing for 2.5h using an ultrasonic oscillator, and measuring the secondary particle size to be 135nm to obtain a dispersion-C containing silane-modified silica nanoparticles.

[0094] In step (2), add 5.8 parts of dispersion-C.

[0095] Example 6 This embodiment provides a hard coating film, which differs from Embodiment 1 in that: The total mass ratio of polar resin and polar monomer to the mass ratio of hydrophobically modified inorganic nanoparticles was 34.7:2.42; the thickness of the hard coating was 4.42 μm.

[0096] The difference between its preparation method and Example 1 is that in step (2), 23.5 parts of high functional group PUA (SHIKOH 7610B, 9-functional PUA), 7.2 parts of hydroxyl-containing polar resin (Kunshan Castel U-Cure 93721, bifunctional PUA) and 5.3 parts of hydroxyl-containing polar monomer (Changxing Chemical EM235, pentaerythritol triacrylate PET3A) are added.

[0097] Example 7 This embodiment provides a hard coating film, which differs from Embodiment 1 in that: The total mass ratio of polar resin and polar monomer to hydrophobically modified inorganic nanoparticles was 54.7:2.42; the thickness of the hard coating was 4.22 μm.

[0098] The difference between its preparation method and Example 1 is that in step (2), 16.3 parts of high functional group PUA (SHIKOH 7610B, 9-functional PUA), 11.2 parts of hydroxyl-containing polar resin (Kunshan Castel U-Cure 93721, bifunctional PUA), and 8.5 parts of hydroxyl-containing polar monomer (Changxing Chemical EM235, pentaerythritol triacrylate PET3A) are added.

[0099] Example 8 This embodiment provides a hard coating film, which differs from Embodiment 1 in that: The hydrophobically modified inorganic nanoparticles are silane-modified alumina nanoparticles with a median particle size D50 of 105 nm; the thickness of the hard coating is 4.38 μm.

[0100] The preparation method differs from that in Example 1 in that: Step (1) includes: adding 2.25g of Dispers 685 wetting and dispersing agent to 85g of toluene, stirring for 10min, then adding 15g of Evonik hydrophobic alumina powder Aeroxide Alu C805, dispersing for 3.0h using an ultrasonic oscillator, and measuring the secondary particle size to be 105nm to obtain a dispersion-D containing silane-modified alumina nanoparticles.

[0101] In step (2), add 5.8 parts of dispersion-D.

[0102] Example 9 This embodiment provides a hard coating film, which differs from Embodiment 1 in that: The hydrophobically modified inorganic nanoparticles are fluorosilane-modified silica nanoparticles with a median particle size D50 of 113 nm; the thickness of the hard coating is 4.16 μm.

[0103] The preparation method differs from that in Example 1 in that: Step (1) includes: mixing 10g of fluorosilane coupling agent SCA-F13C8M, 10g of water, and 180g of ethanol, then adding a certain amount of oxalic acid to the mixture to make the pH of the solution between 4.0 and 4.5, stirring and hydrolyzing for 5.5h to obtain fluorosilanol; Evonik Degussa hydrophilic silica powder Aerosil 200, with a native particle size of 12nm, is placed in a blower dryer and dried at 100℃ for 12h, then 30g of silica powder is added to the above fluorosilanol solution, stirred at 60℃ for 1h, then the mixture is centrifuged and finally dried at 60℃ for 12h to obtain surface-modified silica powder.

[0104] Take 15g of the modified silicon powder and add it to 85g of toluene. After dispersing it using an ultrasonic oscillator for 3.0h, the secondary particle size was measured to be 113nm, and a dispersion-E containing fluorosilane-modified silica nanoparticles was obtained.

[0105] Add 5.8 parts of dispersion-E in step (2).

[0106] Comparative Example 1 This comparative example provides a hard coating film, which differs from Example 1 in that: the hard coating does not contain hydrophobically modified inorganic nanoparticles; the thickness of the hard coating is 4.23 μm.

[0107] The difference between its preparation method and that of Example 1 is that: in step (2), dispersion-A is not added.

[0108] Comparative Example 2 This comparative example provides a hard coating film, which differs from Example 1 in that: hydrophilic inorganic nanoparticles are used instead of hydrophobic modified inorganic nanoparticles in the hard coating, with a median particle size D50 of 288 nm; the thickness of the hard coating is 4.18 μm.

[0109] The preparation method differs from that in Example 1 in that: Step (1) includes: adding 2.25g of Dispers 685 wetting and dispersing agent to 85g of butanone, stirring for 10 minutes, adding 15g of Evonik hydrophilic silica powder Aerosil 200, dispersing for 3.0h using an ultrasonic oscillator, and measuring the secondary particle size to be 288nm to obtain a dispersion-F containing hydrophilic silica nanoparticles.

[0110] In step (2), add 5.8 parts of dispersion-F.

[0111] Comparative Example 3 This comparative example provides a hard coating film, which differs from Example 1 in that: The total mass ratio of polar resin and polar monomer to the mass ratio of hydrophobically modified inorganic nanoparticles was 43.6:1.33; the thickness of the hard coating was 4.21 μm.

[0112] The difference between its preparation method and that of Example 1 is that 3.2 parts of dispersion-A are added in step (2).

[0113] Comparative Example 4 This comparative example provides a hard coating film, which differs from Example 1 in that: The total mass ratio of polar resin and polar monomer to the mass ratio of hydrophobically modified inorganic nanoparticles was 43.6:5.33; the thickness of the hard coating was 4.25 μm.

[0114] The difference between its preparation method and that of Example 1 is that 12.8 parts of dispersion-A are added in step (2).

[0115] Comparative Example 5 This comparative example provides a hard coating film, which differs from Example 1 in that: the median particle size D50 of the hydrophobically modified inorganic nanoparticles is 65 nm; and the thickness of the hard coating is 4.32 μm.

[0116] The preparation method differs from that in Example 1 in that: Step (1) includes: adding 2.25g of Dispers 685 wetting and dispersing agent to 85g of toluene, stirring for 10min, adding 15g of Evonik hydrophobic silica powder Aerosil R974, dispersing for 5.5h using an ultrasonic oscillator, and measuring the secondary particle size to be 65nm to obtain a dispersion-G containing silane-modified silica nanoparticles.

[0117] Add 5.8 parts of dispersion-G in step (2).

[0118] Comparative Example 6 This comparative example provides a hard coating film, which differs from Example 1 in that the median particle size D50 of the hydrophobically modified inorganic nanoparticles is 205 nm. The thickness of the hard coating is 4.22 μm.

[0119] The preparation method differs from that in Example 1 in that: Step (1) includes: adding 2.25 g of Dispers 685 wetting and dispersing agent to 85 g of toluene, stirring for 10 minutes, adding 15 g of Evonik hydrophobic silica powder Aerosil R974, dispersing for 1.0 h using an ultrasonic oscillator, and measuring the secondary particle size to be 205 nm to obtain a dispersion-H containing silane-modified silica nanoparticles.

[0120] In step (2), add 5.8 parts of dispersion-H.

[0121] Comparative Example 7 This comparative example provides a hard coating film, which differs from Example 1 in that: The hydrophobically modified inorganic nanoparticles are acryloyloxy-modified silica nanoparticles with a median particle size D50 of 115 nm; the thickness of the hard coating is 4.27 μm.

[0122] The preparation method differs from that in Example 1 in that: Step (1) includes: adding 2.25g of Dispers 685 wetting and dispersing agent to 85g of toluene, stirring for 10min, then adding 15g of Evonik Aerosil R7200, a silica powder with an acryloxy-modified surface, and dispersing for 3.0h using an ultrasonic vibrator. The secondary particle size was measured to be 115nm, thus obtaining a dispersion-I containing acryloxy-modified silica nanoparticles.

[0123] Add 5.8 parts of dispersion-I in step (2).

[0124] Comparative Example 8 This comparative example provides a hard coating film, which differs from Example 1 in that: the hard coating uses a non-curing matrix, including a cross-linked and cured non-polar resin and non-polar monomer; the thickness of the hard coating is 4.35 μm.

[0125] The preparation method differs from that in Example 1 in that: Replace Kunshan Castel U-Cure 93721 (dual-functional PUA) with Mitsubishi SHIKOH 7605B (6-functional PUA), and replace Changxing Chemical EM235 with Changxing Chemical EM314 (tetrahydrofuran methacrylate, THFMA) and pentaerythritol triacrylate PET3A.

[0126] The composition of some raw materials in the above embodiments and comparative examples is shown in Table 1.

[0127] Table 1. Composition of some raw materials (parts by weight)

[0128] Performance testing and results analysis The hard coatings prepared in the above embodiments and comparative examples were tested respectively, and the test results are shown in Table 2. The specific test methods are as follows: (1) Median particle size D50 of hydrophobically modified inorganic nanoparticles The particle size D50 of microparticles was measured using a laser particle size analyzer (Dandong Bettersize Instruments Co., Ltd., model: Bettersize 2600).

[0129] (2) Hard coating thickness: The thickness was measured using the German NXT coating thickness gauge ETA-SST thickness testing system based on the principle of optical diffraction.

[0130] (3) Haze / Transmittance: According to JIS K-7105 standard, the transmittance (TT) and haze (Hz) of the hard coating film were measured by using a Japanese Denshoku NDH 8000 haze meter and the transmitted light method.

[0131] (4) Surface roughness In accordance with the standard JIS B 0601-1994, the ten-point average roughness Rz (μm) was measured using an ET200A profilometer manufactured by Kosaka Laboratory Ltd. in Japan, with a scanning range of 0.8 mm and a scanning speed of 0.5 mm / s.

[0132] (5) Coefficient of kinetic friction Using the PARAM MXD-02 friction coefficient tester from Jinan Langguang Electromechanical, the hard coating film sample was cut into a length of 200~250 mm and a width of 100~130 mm, placed on the testing table, and fixed with a clamp. The dynamic friction coefficient between the hard coating surfaces was measured at an area of ​​2×2 cm, a load of 200×20 g, a test speed of 100 mm / min, and a stroke of 70 mm.

[0133] (6) Water contact angle Using the CA07R water contact angle measuring instrument from Chang'an Electronics, pure water was injected into one end of the measuring needle connecting tube, and water droplets flowed out from the other end of the needle. A 1cm × 3cm piece of the hard coating to be tested was placed horizontally on the measuring platform with the coated side facing up and secured with tape. The button was rotated to squeeze out a droplet from the needle (set to 2.0μL). The platform with the antireflective film to be tested was raised until it came into contact with the droplet. The water contact angle was calculated using the goniometric method through the measuring software.

[0134] (7) Anti-adhesion The hard coating film was cut into two 20 cm × 20 cm pieces, and the coated surfaces were tightly adhered together. A 5.0 kg weight was used to press them together, and they were placed at room temperature and at 60℃ / 90% humidity for 72 hours respectively. The presence of adhesion was observed. The judgment criteria were as follows: no adhesion - judgment "◎"; slight adhesion - judgment "△"; severe adhesion - judgment "╳".

[0135] Table 2 Performance test results of hard coating film

[0136] As can be seen from Tables 1 and 2, compared with Comparative Examples 1 to 7, the hard coatings prepared in Examples 1 to 9 of this application maintain a water contact angle >90°, a surface roughness of 0.2μm to 0.6μm, and have excellent optical transparency, scratch resistance, long-term anti-blocking properties, and anti-blocking properties under high temperature and high humidity conditions. Among them, the transmittance (TT) is not less than 90%, the haze (Hz) is not higher than 0.8%, there are no interlayer scratches during the finished product winding process, and the coating does not adhere after 72 hours at room temperature, and it can still remain non-adhesive after 72 hours at 60℃ / 90% humidity.

[0137] As can be seen from the comparison between Example 1 and Comparative Example 1, adding an appropriate amount of hydrophobic modified nanoparticles to the hard coating can significantly reduce the dynamic friction coefficient, increase the surface water contact angle and surface roughness while maintaining good optical transparency, thereby improving scratch resistance, long-term anti-adhesion properties and anti-adhesion properties under high temperature and high humidity environments. Figure 2 These are photographs of the appearance of the hard coating films in Example 1 and Comparative Example 1 of this application after a 72-hour anti-blocking test at room temperature. Figure 3 These are photographs showing the appearance of the hard coating films in Example 1 and Comparative Example 1 of this application after finished winding. Figure 2 and Figure 3 It can be seen that the hard coating film prepared in Comparative Example 1 exhibited severe adhesion during the anti-adhesion test and the finished product winding process, with obvious watermarks appearing on the surface.

[0138] As can be seen from the comparison between Example 1 and Comparative Example 2, the hydrophilic nanoparticles used in Comparative Example 2 are prone to agglomeration and are not easy to disperse, resulting in a significant increase in their D50. The surface roughness Rz of the hard coating is too high, which leads to reduced transparency and increased haze. In high temperature and high humidity environments, they are prone to absorbing water and causing re-adhesion, resulting in poor anti-adhesion effect. At the same time, due to the hydrophilicity of the particle surface, the higher dyne value increases the dynamic friction coefficient of the hard coating film, which is prone to scratching the interlayer film surface during finished product winding, causing short and fine contact scratches.

[0139] A comparison of Example 1 and Comparative Examples 3 and 4 shows that in Comparative Example 3, the amount of hydrophobic modified nanoparticles added was too low, resulting in a low surface roughness Rz of the hard coating film and a reduced water contact angle. This significantly reduced the anti-blocking effect under both normal temperature and high temperature / humidity conditions. In Comparative Example 4, the amount of hydrophobic modified nanoparticles added was too high, leading to an excessively high surface roughness of the hard coating film. Although the anti-blocking effect was good, the transmittance of the hard coating film decreased, and the haze significantly increased, resulting in reduced optical transparency.

[0140] A comparison of Example 1 and Comparative Examples 5 and 6 shows that the median particle size D50 of the hydrophobic modified nanoparticles in Comparative Example 5 is relatively small, resulting in a low surface roughness Rz of the hard coating film and a reduced water contact angle. This significantly reduces the anti-blocking effect under both normal temperature and high temperature / humidity conditions. In Comparative Example 6, the median particle size D50 of the hydrophobic modified nanoparticles is relatively large, leading to a high surface roughness Rz of the hard coating film. Although the anti-blocking effect is good, the transmittance is reduced, the haze is significantly increased, and the optical transparency is decreased.

[0141] As can be seen from the comparison between Example 1 and Comparative Example 7, the hydrophobic modified nanoparticles added in Comparative Example 7 contain acryloyloxy groups on their surface. Their unsaturated double bonds participate in the curing and crosslinking reaction together with the resin and monomer during the UV curing process. Therefore, they cannot fully migrate and accumulate to the coating surface, resulting in a low surface roughness Rz of the hard coating film, a reduced water contact angle, an increased interlayer dynamic friction coefficient, and poor anti-blocking effect under both room temperature and high temperature and high humidity environments.

[0142] As can be seen from the comparison between Example 1 and Comparative Example 8, the non-polar UV resin used in Comparative Example 8 has a high chemical affinity with the hydrophobic modified nanoparticles, and the particles cannot effectively migrate and accumulate to the coating surface, resulting in a low surface roughness Rz of the hard coating film, an increased interlayer dynamic friction coefficient, and poor anti-blocking effect under both normal temperature and high temperature and high humidity environments.

[0143] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A hard coating film, characterized in that, The coating comprises a substrate layer and a hard coating layer disposed on the surface of the substrate layer; the hard coating layer comprises a cured matrix and hydrophobically modified inorganic nanoparticles dispersed in the cured matrix, the cured matrix comprising a cross-linked and cured polar resin and a polar monomer, at least a portion of the hydrophobically modified inorganic nanoparticles protruding from the surface of the hard coating layer to form multiple protrusions; wherein, the water contact angle of the surface of the hard coating film is >90°, and the surface roughness is 0.2μm~0.6μm.

2. The hard coating film according to claim 1, characterized in that, The hydrophobic modified inorganic nanoparticles include at least one of hydrophobic modified silica nanoparticles, hydrophobic modified alumina nanoparticles, or hydrophobic modified titanium dioxide nanoparticles.

3. The hard coating film according to claim 1, characterized in that, The surface of the hydrophobically modified inorganic nanoparticles does not have functional groups containing carbon-carbon double bonds grafted onto it.

4. The hard coating film according to claim 1, characterized in that, The median particle size D50 of the hydrophobically modified inorganic nanoparticles is 50 nm to 150 nm. Optionally, the thickness of the hard coating is 3μm to 5μm.

5. The hard coating film according to claim 1, characterized in that, The polar resin includes at least one of the cured resins containing hydroxyl, amino, or carboxyl groups; And / or, the polar monomer includes at least one of the cured monomers containing hydroxyl, amino, or carboxyl groups; Optionally, the polar resin includes at least one of polyurethane acrylate, epoxy acrylate, or polyester acrylate; Optionally, the polar monomer includes at least one of pentaerythritol triacrylate, hydroxyhexyl acrylate, hydroxyhexyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, or glyceryl monoacrylate.

6. The hard coating film according to claim 1, characterized in that, The total mass ratio of the polar resin and the polar monomer to the mass ratio of the hydrophobically modified inorganic nanoparticles is (30~80):(1.5~5.0).

7. A method for preparing a hard coating film as described in any one of claims 1 to 6, characterized in that, Includes the following steps: The substrate to be cured, the hydrophobically modified inorganic nanoparticles, and the first solvent are mixed to obtain a hard coating liquid; wherein the substrate to be cured includes a polar resin and a polar monomer; The hard coating liquid is applied to the surface of the substrate layer, and then dried and cured with ultraviolet light in sequence to crosslink and cure the matrix to be cured to form the cured matrix. The hydrophobic modified inorganic nanoparticles are dispersed in the cured matrix to form the hard coating layer, thereby obtaining the hard coating film.

8. The preparation method according to claim 7, characterized in that, The polar resin includes at least one of curable resins containing hydroxyl, amino, or carboxyl groups, and the polar monomer includes at least one of curable monomers containing hydroxyl, amino, or carboxyl groups; based on the total mass of the matrix to be cured, the total mass ratio of the polar resin and the polar monomer is 30wt% to 80wt%. And / or, based on the total mass of the matrix to be cured, the mass percentage of the hydrophobic modified inorganic nanoparticles is 1.5wt%~5.0wt%.

9. The preparation method according to claim 7, characterized in that, The mixing step includes: dispersing the hydrophobically modified inorganic nanoparticles in a second solvent to obtain a dispersion; mixing the dispersion, the matrix to be cured, and the first solvent to obtain the hard coating liquid; Optionally, the polarity of the second solvent is lower than that of the first solvent.

10. The preparation method according to claim 7, characterized in that, The preparation method of the hydrophobically modified inorganic nanoparticles includes: Inorganic nanoparticles were surface-grafted and modified using silane coupling agents or fluorosilane coupling agents. The inorganic nanoparticles include at least one of silicon dioxide, aluminum oxide, or titanium oxide; the mass ratio of the silane coupling agent or fluorosilane coupling agent to the inorganic nanoparticles is (0.2~0.6):1.

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