Hard-coated film, optical member, and image display device

Abstract

To achieve the above object, a hard coat film (100a) and (100b) of the present application is characterized by comprising a substrate (110), a first hard coat layer (101), a second hard coat layer (102), and a third hard coat layer (103), the first hard coat layer (101), the second hard coat layer (102), the substrate, and the third hard coat layer (103) being stacked in this order from a visually recognizable side, the first hard coat layer (101) and the second hard coat layer (102) each containing nano-sized silica particles, the weight average particle diameter of the nano-sized silica particles (101P) contained in the first hard coat layer (101) being larger than the weight average particle diameter of the nano-sized silica particles (102P) contained in the second hard coat layer (102).

Description

Technical Field

[0001] This invention relates to hard-coated thin films, optical components, and image display devices. Background Technology

[0002] Hard-coated films are thin films with a hard coating on their surface that improve scratch resistance and other properties, and are widely used in image display devices (Patent Document 1, etc.).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-221746 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] However, increasing the hardness of the hard coating may cause the hard coating film to curl due to curing shrinkage. On the other hand, reducing curing shrinkage may result in a decrease in the hardness of the hard coating. In other words, for hard coating films, there is a trade-off between hardness and the prevention of curling.

[0008] In addition, sometimes other layers, such as an anti-reflective layer, are further laminated on the visual recognition side surface of the hard coating. However, if the hardness of the hard coating surface is set too high, there is a risk that the adhesion between the visual recognition side surface and other layers will decrease.

[0009] Therefore, the object of the present invention is to provide a hard-coated thin film with high hardness, suppressed curling, and high adhesion between the visual recognition side surface and other layers, an optical component, and an image display device.

[0010] Solution for solving the problem

[0011] To achieve the above objectives, the hard-coated film of the present invention is characterized in that,

[0012] It includes a substrate, a first hard coating, a second hard coating, and a third hard coating.

[0013] The first hard coating, the second hard coating, the substrate, and the third hard coating are layered in this order, starting from the visual recognition side.

[0014] The first hard coating and the second hard coating described above each contain nano-silica particles.

[0015] The weight-average particle size of the nano-silica particles contained in the first hard coating is greater than that of the nano-silica particles contained in the second hard coating.

[0016] The optical component of the present invention is an optical component comprising the hard coating film of the present invention.

[0017] The image display device of the present invention is an image display device comprising the hard coating film of the present invention or the optical component of the present invention.

[0018] The effects of the invention

[0019] According to the present invention, a hard-coated thin film with high hardness, suppressed curling, and high adhesion between the visual recognition side surface and other layers can be provided, as well as optical components and image display devices. Attached Figure Description

[0020] Figure 1 A cross-sectional view of the structure of the hard coating film of the present invention is shown as an example.

[0021] Figure 2 A cross-sectional view illustrating an example of a hard-coated film of the present invention being laminated onto a glass plate.

[0022] Figure 3 A process cross-sectional view of the manufacturing process of the hard coating film of the present invention is shown as an example.

[0023] Explanation of reference numerals in the attached figures

[0024] 100a, 100b hard-coated films

[0025] 101 First Hard Coating

[0026] 102 Second Hard Coating

[0027] 103 Third Hard Coating

[0028] 101P, 102P, 103P nano-silica particles

[0029] 110 Substrate

[0030] 120 Protective Film

[0031] 210 glass plate

[0032] 220 Adhesive Layer Detailed Implementation

[0033] Next, examples will be given to further illustrate the invention. However, the invention is not limited by the following description.

[0034] Regarding the hard coating film of the present invention, for example, the third hard coating layer described above may not contain nano-silica particles.

[0035] Regarding the hard coating film of the present invention, for example, the thickness of the third hard coating layer may be less than the combined thickness of the first hard coating layer and the second hard coating layer.

[0036] For example, the hard coating film of the present invention may have the following characteristics: the weight-average particle size of the nano-silica particles contained in the first hard coating layer is 30-50 nm, and the weight-average particle size of the nano-silica particles contained in the second hard coating layer is 5-30 nm.

[0037] For example, the hard-coated film of the present invention can have an overall light transmittance of 90% or more at a wavelength of 550 nm.

[0038] The optical components of the present invention may be, for example, polarizing plates.

[0039] It should be noted that in this invention, "weight" and "mass" can be used interchangeably unless otherwise specified. For example, "parts by mass" can be replaced with "parts by weight", "parts by weight" can be replaced with "parts by mass", "mass%" can be replaced with "weight%", and "weight%" can be replaced with "mass%".

[0040] [1. Hard coating film]

[0041] As described above, in the hard-coated film of the present invention, the weight-average particle size of the nano-silica particles contained in the first hard coating layer is greater than the weight-average particle size of the nano-silica particles contained in the second hard coating layer. That is, the weight-average particle size of the nano-silica particles contained in the first hard coating layer and the weight-average particle size of the nano-silica particles contained in the second hard coating layer satisfy the following relationship (1).

[0042] Ra>Rb(1)

[0043] In formula (1) above, Ra is the weight-average particle size [nm] of the nano-silica particles contained in the first hard coating layer. Rb is the weight-average particle size [nm] of the nano-silica particles contained in the second hard coating layer.

[0044] Figure 1A cross-sectional view (a) shows an example of the structure of the hard-coated film of the present invention. As shown, the hard-coated film 100a includes a substrate 110, a first hard coating layer 101, a second hard coating layer 102, and a third hard coating layer 103. As shown, the first hard coating layer 101, the second hard coating layer 102, the substrate 110, and the third hard coating layer 103 are stacked in this order, starting from the visual recognition side. In other words, the second hard coating layer 102 and the first hard coating layer 101 are sequentially stacked on one side of the substrate 110 (the side facing the visual recognition side), and the third hard coating layer 103 is stacked on the other side of the substrate 110 (the side facing the visual recognition side). The first hard coating layer 101 includes nano-silica particles 101P. The second hard coating layer 102 includes nano-silica particles 102P. Furthermore, the weight-average particle size (Ra of the above mathematical formula (1)) of the nano-silica particles 101P contained in the first hard coating 101 is greater than the weight-average particle size (Rb of the above mathematical formula (1)) of the nano-silica particles 102P contained in the second hard coating 102.

[0045] in addition, Figure 1 The cross-sectional view (b) shows another example of the composition of the hard-coated film of the present invention. As shown, this hard-coated film 100b, except that the third hard coating layer 103 contains nano-silica particles 103P, is similar to... Figure 1 The hard coating film 100a of (a) is the same.

[0046] As described above, the hard-coated film of the present invention has high hardness and suppresses curling. Specifically, curling is suppressed, for example, by laminating hard coatings on both sides of the substrate, and high hardness is achieved by laminating the first hard coating and the second hard coating on the surface side (visual recognition side). Therefore, the hard-coated film of the present invention can be used not only as a component of a polarizing plate, but also as a front panel.

[0047] The hard-coated film of the present invention can be used, for example, as a transparent film or an anti-glare film (also known as an AG film). For example, the outermost layer on the visual recognition side (e.g., the first hard coating layer described above) can be made anti-glare (AG) for use as an anti-glare film.

[0048] Furthermore, the hard-coated film of the present invention may or may not include layers other than the aforementioned substrate, the first hard coating layer, the second hard coating layer, and the third hard coating layer. For example, the aforementioned substrate, the first hard coating layer, the second hard coating layer, and the third hard coating layer may be directly laminated, or they may be laminated using other layers such as adhesive layers. Additionally, for example, the aforementioned first hard coating layer and the aforementioned third hard coating layer may each have other layers laminated on their outer sides, or they may not have other layers laminated. Specifically, for example, by laminating an anti-reflective layer (also called an AR layer) as another layer on the outer side of the aforementioned first hard coating layer, an anti-reflective effect can also be imparted. The aforementioned anti-reflective layer is not particularly limited; for example, it may be a DRY-AR layer (an AR layer formed by a dry method such as sputtering or vapor deposition). Additionally, for example, an adhesive / bonding layer may be formed on the outer side of the aforementioned third hard coating layer. The aforementioned other layers may be formed, for example, by coating. As described above, the visual recognition side surface of the hard-coated film of the present invention has high adhesion to other layers. More specifically, the hard-coated film of the present invention, for example, exhibits high adhesion between the surface of the first hard coating layer (with a large weight-average particle size of the nano-silica particles) and other layers, making it suitable for providing an anti-reflective layer (e.g., a DRY-AR layer) as another layer on the first hard coating layer. Furthermore, the hard-coated film of the present invention exhibits high hardness, for example, due to the presence of a second hard coating layer (with a small weight-average particle size of the nano-silica particles) between the first hard coating layer (with a large weight-average particle size of the nano-silica particles) and the substrate. Moreover, as described above, the hard-coated film of the present invention can suppress curling, thus exhibiting good transportability when forming other layers through coating.

[0049] It should be noted that in this invention, "adhesive / bonding layer" refers to "adhesive layer or bonding layer." "Adhesive layer" means "a layer formed by an adhesive." "Bonding layer" means "a layer formed by an adhesive agent." Generally, sometimes a substance with relatively low adhesive strength (bonding force) that allows for the re-peeling of the adhered objects is called an "adhesive," while a substance with relatively high adhesive strength (bonding force) that makes re-peeling of the adhered objects difficult or impossible is called an "adhesive agent," thus distinguishing between the two. In this invention, a substance with relatively low adhesive strength (bonding force) is called an "adhesive," and a substance with relatively high adhesive strength (bonding force) is called an "adhesive agent," but there is no clear distinction between the two.

[0050] In the hard-coated film of the present invention, the materials of the substrate, the first hard coating layer, the second hard coating layer, and the third hard coating layer are not particularly limited, and can be the same as or similar to those of conventional hard-coated films. Specific examples will be shown in the manufacturing method of the hard-coated film of the present invention described later. The nano-silica particles are also not particularly limited, and can be the same as or similar to those of conventional hard-coated films. By using the same material as such conventional hard-coated films (no special materials, processing, etc. are required), the hard-coated film of the present invention can achieve both high hardness and suppression of curling without sacrificing appearance, display characteristics, etc.

[0051] In recent years, for example, in laptop displays, even large-sized displays, there has been an ongoing process of integrating touch sensors into the liquid crystal cells (embedded touch sensors). Furthermore, from the viewpoints of lightweighting, thinning, and ease of processing, there is a demand for glass-free structures in laptop displays (structures that do not use glass in the display). For example, the hard-coated film of this invention has high hardness, thereby also meeting this requirement.

[0052] The third hard coating layer in the hard coating film of the present invention may contain nano-silica particles, or it may not contain nano-silica particles as described above. The absence of nano-silica particles in the third hard coating layer facilitates further improvement in the hardness of the hard coating film, and is therefore preferred. If the third hard coating layer does not contain nano-silica particles, for example, the third hard coating layer is less prone to cracking (crazing) caused by bending. Furthermore, if the third hard coating layer does not contain nano-silica particles, for example, even if a thick adhesive / bonding layer is formed on the outer side of the third hard coating layer, the third hard coating layer is less prone to cracking caused by scratching, etc. In addition, by eliminating nano-silica particles from the third hard coating layer, it also has advantages such as significantly reducing material costs and improving the processability of the hard coating film.

[0053] In this invention, the thickness of the substrate is not particularly limited. From the viewpoints of strength, processability, and thinness, it can be, for example, 80 μm or more, 90 μm or more, 100 μm or more, 110 μm or more, or 120 μm or more; or, for example, 60 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, or 20 μm or less; or, for example, 10–40 μm, 40–70 μm, 70–100 μm, 100–130 μm, or 130–160 μm. From the viewpoint of thinness, the thickness of the substrate is preferably not too large, and from the viewpoint of maintaining hardness, it is preferably not too small.

[0054] In this invention, the thickness of the first hard coating layer is not particularly limited. For example, it can be 0.1 μm or more, 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, or 10 μm or more. For example, it can be 30 μm or less, 20 μm or more, 10 μm or more, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. For example, it can be 0.1–30 μm, 0.1–20 μm, 0.1–10 μm, 0.1–5 μm, 1–30 μm, 1–20 μm, 1–10 μm, 1–5 μm, 5–30 μm, 5–20 μm, 5–10 μm, 0.1–1 μm, 1–5 μm, 5–10 μm, 10–20 μm, or 20–30 μm. Regarding the thickness of the first hard coating mentioned above, from the viewpoint of processability and flexibility, it is preferable that it is not too large, and from the viewpoint of hardness, it is preferable that it is not too small.

[0055] In this invention, the thickness of the second hard coating is not particularly limited, and can be, for example, 0.1 μm or more, 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, or 5 μm or more; and can be, for example, less than 50 μm, less than 30 μm, less than 20 μm, less than 15 μm, less than 10 μm, less than 5 μm, less than 4 μm, less than 3 μm, less than 2 μm, or less than 1 μm. The thickness of the second hard coating is 0.1–50 μm, 0.1–30 μm, 0.1–20 μm, 0.1–10 μm, 0.1–5 μm, 1–50 μm, 1–30 μm, 1–20 μm, 1–10 μm, 5–50 μm, 5–30 μm, 5–20 μm, 10–50 μm, 0.1–1 μm, 1–5 μm, 5–10 μm, 10–20 μm, or 20–50 μm. Regarding the thickness of the second hard coating, from the viewpoint of processability and flexibility, it is preferable that it is not too large; from the viewpoint of hardness, it is preferable that it is not too small.

[0056] In this invention, the thickness of the third hard coating is not particularly limited, and can be, for example, 0.1 μm or more, 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, or 5 μm or more; and can be, for example, less than 50 μm, less than 30 μm, less than 20 μm, less than 15 μm, less than 10 μm, less than 5 μm, less than 4 μm, less than 3 μm, less than 2 μm, or less than 1 μm. The thicknesses are 0.1–50 μm, 0.1–30 μm, 0.1–20 μm, 0.1–10 μm, 0.1–5 μm, 1–50 μm, 1–30 μm, 1–20 μm, 1–10 μm, 5–50 μm, 5–30 μm, 5–20 μm, 10–50 μm, 0.1–1 μm, 1–5 μm, 5–10 μm, 10–20 μm, or 20–50 μm. Regarding the thickness of the third hard coating, from the viewpoint of processability and flexibility, it is preferable that it is not too large; from the viewpoint of hardness, it is preferable that it is not too small.

[0057] It should be noted that in the hard-coated film of the present invention, when the thickness of any layer, including the substrate, is not uniform (for example, when the surface of the layer is uneven), the “thickness” of the layer refers to the average thickness.

[0058] For example, as described above, the thickness of the third hard coating layer of the hard-coated film of the present invention can be less than the combined thickness of the first hard coating layer and the second hard coating layer. That is, the thicknesses of the first hard coating layer, the second hard coating layer, and the third hard coating layer can satisfy the relationship of the following mathematical formula (2). By making the thickness of the third hard coating layer smaller in this way, it has the following effects, such as reducing the overall thickness of the hard-coated film, making the hard-coated film lighter overall, improving the processability of the hard-coated film, reducing material costs, and suppressing cracks (crazing) when the hard-coated film is bent.

[0059] Tab>Tc(2)

[0060] In the above mathematical formula (2), Tab is the total thickness of the first hard coating and the second hard coating [μm]. Tc is the thickness of the third hard coating [μm].

[0061] As described above, the hard coating film of the present invention, for example, forms an antireflective layer on the first hard coating layer with a large weight-average particle size of nano-silica particles, thereby achieving high adhesion between the hard coating layer and the antireflective layer (e.g., a DRY-AR layer). Furthermore, the hard coating film of the present invention, for example, has high hardness due to the presence of a second hard coating layer with a small weight-average particle size of nano-silica particles between the first hard coating layer and the substrate.

[0062] It should be noted that, in this invention, "nano-silica particles" refers to silica particles with a weight-average particle size of approximately several hundred nm or less. The weight-average particle size of "nano-silica particles" is not particularly limited in this invention; for example, it can be above 1 nm, above 10 nm, above 50 nm, above 100 nm, above 150 nm, above 200 nm, or above 250 nm; for example, it can be below 300 nm, below 250 nm, below 200 nm, below 100 nm, below 50 nm, below 40 nm, below 30 nm, below 20 nm, or below 10 nm; for example, it can be 1–300 nm. m, 1~250nm, 1~200nm, 1~100nm, 1~50nm, 10~300nm, 10~250nm, 10~200nm, 10~100nm, 50~300nm, 50~250nm, 50~200nm, 50~100nm, 100~300nm, 100~250nm, 1~10nm, 10~50nm, 50~100nm, 100~200nm, or 200~300nm.

[0063] It should be noted that the method for determining the weight-average particle size in this invention is not particularly limited, and for example, as described below. For instance, the average particle size of the nanoparticles in the hard coating can be determined by TEM (Transmission Electron Microscope) analysis of the cross-section of the aforementioned hard coating, and this can be inferred as the weight-average particle size. Specifically, the average particle size (the value obtained by adding the major and minor axes and dividing by 2) of all particles observed in a 0.5 μm × 0.5 μm region of the cross-section can be inferred as the weight-average particle size. Furthermore, when determining the weight-average particle size of the aforementioned nanoparticles in a material (solution) containing dispersed nanoparticles, light scattering and diffraction methods can be used, for example.

[0064] In this invention, the weight-average particle size of the nano-silica particles contained in the first hard coating is not particularly limited. For example, it can be 1 nm or more, 10 nm or more, 50 nm or more, 100 nm or more, 150 nm or more, 200 nm or more, or 250 nm or more. Alternatively, it can be less than 300 nm, less than 250 nm, less than 200 nm, less than 100 nm, less than 50 nm, less than 40 nm, less than 30 nm, less than 20 nm, or less than 10 nm. For example, it can be 1 nm or more. ~300nm, 1~250nm, 1~200nm, 1~100nm, 1~50nm, 10~300nm, 10~250nm, 10~200nm, 10~100nm, 50~300nm, 50~250nm, 50~200nm, 50~100nm, 100~300nm, 100~250nm, 1~10nm, 10~50nm, 50~100nm, 100~200nm, or 200~300nm. Regarding the weight-average particle size of the aforementioned nano-silica particles contained in the first hard coating layer, from the viewpoint of film transparency, it is preferable that it is not too large, and from the viewpoint of adhesion to the anti-reflective layer (AR layer), it is preferable that it is not too small.

[0065] In this invention, the weight-average particle size of the nano-silica particles contained in the second hard coating is not particularly limited. For example, it can be 1 nm or more, 10 nm or more, 50 nm or more, 100 nm or more, 150 nm or more, 200 nm or more, or 250 nm or more. Alternatively, it can be less than 300 nm, less than 250 nm, less than 200 nm, less than 100 nm, less than 50 nm, less than 40 nm, less than 30 nm, less than 20 nm, or less than 10 nm. For example, it can be 1 nm or more. ~300nm, 1~250nm, 1~200nm, 1~100nm, 1~50nm, 10~300nm, 10~250nm, 10~200nm, 10~100nm, 50~300nm, 50~250nm, 50~200nm, 50~100nm, 100~300nm, 100~250nm, 1~10nm, 10~50nm, 50~100nm, 100~200nm, or 200~300nm. Regarding the weight-average particle size of the aforementioned nano-silica particles contained in the second hard coating, from the viewpoint of film transparency, it is preferable that it is not too large, and from the viewpoint of film hardness, it is preferable that it is not too small.

[0066] As described above, the third hard coating may or may not contain nano-silica particles. When the third hard coating contains nano-silica particles, the weight-average particle size of the nano-silica particles is not particularly limited, and may, for example, be 1 nm or more, 10 nm or more, 50 nm or more, 100 nm or more, 150 nm or more, 200 nm or more, or 250 nm or more; or, for example, less than 300 nm, less than 250 nm, less than 200 nm, less than 100 nm, less than 50 nm, less than 40 nm, less than 30 nm, less than 20 nm, or less than 10 nm. The particle sizes are 1–300 nm, 1–250 nm, 1–200 nm, 1–100 nm, 1–50 nm, 10–300 nm, 10–250 nm, 10–200 nm, 10–100 nm, 50–300 nm, 50–250 nm, 50–200 nm, 50–100 nm, 100–300 nm, 100–250 nm, 1–10 nm, 10–50 nm, 50–100 nm, 100–200 nm, or 200–300 nm. Regarding the weight-average particle size of the aforementioned nano-silica particles contained in the third hard coating, from the viewpoint of film transparency, it is preferable that the size is not too large, and from the viewpoint of film hardness, it is preferable that the size is not too small.

[0067] As described above, the hard coating film of the present invention may, for example, have a weight-average particle size of 30 to 50 nm for the nano-silica particles contained in the first hard coating layer and a weight-average particle size of 5 to 30 nm for the nano-silica particles contained in the second hard coating layer.

[0068] Furthermore, in the aforementioned first hard coating, the content of the aforementioned nano-silica particles relative to the total mass (weight) of the aforementioned first hard coating can be, for example, 1% or more by mass, 20% or more by mass, 30% or more by mass, 40% or more by mass, 50% or more by mass, 60% or more by mass, 70% or more by mass, 80% or more by mass, or 90% or more by mass; for example, it can be less than 100% by mass, less than 90% by mass, less than 80% by mass, less than 70% by mass, less than 60% by mass, less than 50% by mass, less than 40% by mass, less than 30% by mass, or less than 20% by mass; for example, it can be 1 to 90% by mass, or 1 to 80% by mass. The percentages are as follows: 1–70% by mass, 1–60% by mass, 1–50% by mass, 1–40% by mass, 20–90% by mass, 20–80% by mass, 20–70% by mass, 20–60% by mass, 20–50% by mass, 30–90% by mass, 30–80% by mass, 30–70% by mass, 30–60% by mass, 30–50% by mass, 30–40% by mass, 40–90% by mass, 40–80% by mass, 40–70% by mass, 40–50% by mass, 60–90% by mass, 1–20% by mass, 20–40% by mass, 40–60% by mass, 60–80% by mass, or 80–90% by mass. Regarding the content of the aforementioned nano-silica particles in the first hard coating, from the viewpoint of processability and flexibility, it is preferable that the content is not too high; from the viewpoint of hardness, it is preferable that the content is not too low.

[0069] In the second hard coating described above, the content of the aforementioned nano-silica particles relative to the total mass (weight) of the second hard coating can, for example, be 1% or more by mass, 20% or more by mass, 30% or more by mass, 40% or more by mass, 50% or more by mass, 60% or more by mass, 70% or more by mass, 80% or more by mass, or 90% or more by mass; or, for example, less than 100% by mass, less than 90% by mass, less than 80% by mass, less than 70% by mass, less than 60% by mass, less than 50% by mass, less than 40% by mass, less than 30% by mass, or less than 20% by mass; or, for example, 1 to 90% by mass, 1 to 80% by mass. 1–70% by mass, 1–60% by mass, 1–50% by mass, 1–40% by mass, 20–90% by mass, 20–80% by mass, 20–70% by mass, 20–60% by mass, 20–50% by mass, 30–90% by mass, 30–80% by mass, 30–70% by mass, 30–60% by mass, 30–50% by mass, 30–40% by mass, 40–90% by mass, 40–80% by mass, 40–70% by mass, 40–50% by mass, 60–90% by mass, 1–20% by mass, 20–40% by mass, 40–60% by mass, 60–80% by mass, or 80–90% by mass. Regarding the content of the aforementioned nano-silica particles in the second hard coating, from the viewpoint of processability and flexibility, it is preferable that it is not too high; from the viewpoint of hardness, it is preferable that it is not too low.

[0070] In the aforementioned third hard coating, the content of the aforementioned nano-silica particles relative to the total mass (weight) of the aforementioned third hard coating can, for example, be 1% or more by mass, 20% or more by mass, 30% or more by mass, 40% or more by mass, 50% or more by mass, 60% or more by mass, 70% or more by mass, 80% or more by mass, or 90% or more by mass; for example, it can be less than 100% by mass, less than 90% by mass, less than 80% by mass, less than 70% by mass, less than 60% by mass, less than 50% by mass, less than 40% by mass, less than 30% by mass, or less than 20% by mass; for example, it can be 1 to 90% by mass, 1 to 80% by mass. 1–70% by mass, 1–60% by mass, 1–50% by mass, 1–40% by mass, 20–90% by mass, 20–80% by mass, 20–70% by mass, 20–60% by mass, 20–50% by mass, 30–90% by mass, 30–80% by mass, 30–70% by mass, 30–60% by mass, 30–50% by mass, 30–40% by mass, 40–90% by mass, 40–80% by mass, 40–70% by mass, 40–50% by mass, 60–90% by mass, 1–20% by mass, 20–40% by mass, 40–60% by mass, 60–80% by mass, or 80–90% by mass. Regarding the content of the aforementioned nano-silica particles in the third hard coating, from the viewpoint of processability and flexibility, it is preferable that the content is not too high; from the viewpoint of hardness, it is preferable that the content is not too low.

[0071] The hard-coated film of the present invention, as described above, has a transmittance of 90% or more at a wavelength of 550 nm. The transmittance of the hard-coated film at a wavelength of 550 nm can be, for example, 90% or more, 92% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more; for example, it can be less than 100%, less than 99%, less than 98%, less than 97%, less than 96%, less than 95%, less than 94%, less than 93%, less than 92%, or less than 90%; for example, it can be 90-100%, 90-99%, 90-98%, 90-97%, 90-96%, 90-95%, 90-94%, 90-93%, or 90-92%. 92–100%, 92–99%, 92–98%, 92–97%, 92–96%, 92–95%, 92–94%, 92–93%, 94–100%, 94–99%, 94–98%, 94–97%, 94–96%, 94–95%, 95–100%, 95–99%, 95–98%, 95–97%, 95–96%, 96–100%, 96–99%, 96–98%, 96–97%, 97–100%, 97–99%, 97–98%, 98–100%, 98–99%, or 99–100%. By achieving high overall light transmittance of the hard-coated film, advantages such as not compromising brightness when manufacturing polarizing plates and facilitating visual inspection due to high transparency are achieved.

[0072] It should be noted that the method for measuring transmittance in this invention is not particularly limited. For example, it can be measured using the following methods.

[0073] [Methods for measuring light transmittance]

[0074] • Apparatus: Integrating sphere spectrophotometer (trade name: DOT-3C, manufactured by Murakami Color Technology Research Institute)

[0075] Measurement mode: Total transmittance & color calculation

[0076] • Light source: D65 light source

[0077] • Field of view: 2 degrees

[0078] • The transmittance at a wavelength of 550 nm was measured under the above settings at an air temperature of 23 degrees Celsius and a humidity of 50%.

[0079] [2. Manufacturing method of hard-coated film]

[0080] The method for manufacturing the hard-coated film of the present invention is not particularly limited, and can be carried out in the same way as the conventional method for manufacturing hard-coated films. Examples are given below to illustrate the method for manufacturing the hard-coated film of the present invention.

[0081] exist Figure 3 The process cross-sectional views (a) to (d) show an example of the method for manufacturing the hard-coated film of the present invention.

[0082] First, such as Figure 3 Prepare the substrate 110 as shown in (a) and form a third hard coating 103 on one side thereon.

[0083] The substrate 110 is not particularly limited, and can be, for example, a light-transmitting substrate, such as a transparent plastic film substrate. The transparent plastic film substrate is not particularly limited, but it is preferable to have excellent visible light transmittance (preferably 90% or more) and excellent transparency (preferably a haze value of 1% or less), such as the transparent plastic film substrate described in Japanese Patent Application Publication No. 2008-90263. As the transparent plastic film substrate, it is suitable to use one with low optical birefringence. The hard-coated film of the present invention can also be used as a protective film for a polarizing plate, for example. In this case, as the transparent plastic film substrate, a film formed from cellulose triacetate (TAC), polycarbonate, acrylic polymers, or polyolefins having a cyclic or norbornene structure is preferred. Furthermore, in the present invention, the transparent plastic film substrate can be the polarizing element itself. With such a configuration, a protective layer formed from TAC or the like is not required, simplifying the structure of the polarizing plate, thus reducing the number of manufacturing steps for the polarizing plate or image display device and improving production efficiency. In addition, with such a configuration, the polarizing plate can be further thinned. It should be noted that when the aforementioned transparent plastic film substrate is a polarizing element, for example, the aforementioned non-transparent layer functions as a protective layer. Furthermore, with this configuration, the hard-coated film of the present invention also functions as a cover plate when mounted on the surface of a liquid crystal cell.

[0084] In this invention, the thickness of the substrate is not particularly limited, for example, as described above. The refractive index of the substrate is not particularly limited. For example, the refractive index is in the range of 1.30 to 1.80 or 1.40 to 1.70.

[0085] It should be noted that in this invention, "refractive index" refers to the refractive index at a wavelength of 550 nm unless otherwise specified. Furthermore, the method for measuring the refractive index is not particularly limited in this invention. For the refractive index of fine materials such as particles, the Beck method can be used, for example. The Beck method is a method in which the refractive index of the standard refractive liquid is measured when the sample is dispersed on a glass slide in a standard refractive liquid and the outline of the sample disappears or becomes blurred when observed under a microscope. Additionally, the method for measuring the refractive index of objects whose refractive index cannot be measured by the Beck method (e.g., anti-glare films, anti-glare layers, or resins constituting anti-glare layers) is not particularly limited. For example, a conventional refractometer (a device for measuring refractive index) can be used. The refractometer itself is not particularly limited; examples include Abbe refractometers. An example of an Abbe refractometer is the multi-wavelength Abbe refractometer DR-M2 / 1550 (trade name) manufactured by ATAGO CO.,LTD.

[0086] The method for forming the third hard coating 103 on the substrate 110 is not particularly limited, and may be as described below. Hereinafter, the process of forming the third hard coating 103 will sometimes be referred to as the "third hard coating forming process." The third hard coating forming process may include, for example, a coating process of applying a coating liquid for forming the third hard coating (hereinafter sometimes simply referred to as "coating liquid" or "third hard coating forming material") to the substrate 110, and a coating film forming process of drying the applied coating liquid to form a coating film. Additionally, the third hard coating forming process may also include, for example, a curing process of curing the coating film. The curing may be performed after drying, but is not limited thereto. The curing may be performed by heating, light irradiation, etc. The light source is not particularly limited, and may be, for example, ultraviolet light. The light source for the light irradiation is also not particularly limited, and may be, for example, a high-pressure mercury lamp.

[0087] The aforementioned coating liquid (third hard coating forming material) may, for example, be a coating liquid containing a resin material and a diluent (hereinafter sometimes simply referred to as "solvent"). Furthermore, the aforementioned coating liquid may contain other components besides these, or it may not contain any. As for the aforementioned other components, there are no particular limitations, but examples include thixotropic agents and the aforementioned nano-silica particles. It should be noted that... Figure 3 An example is shown where the third hard coating 103 comprises nano-silica particles 103P. However, as described above, the aforementioned third hard coating of the hard coating film of the present invention may or may not contain nano-silica particles.

[0088] The resin material contained in the coating liquid may be, for example, the resin itself that forms the third hard coating layer 103, or a resin material formed by polymerization, curing, or the like. The resin is not particularly limited and may, for example, be a thermosetting resin or an ionizing radiation-curing resin. Furthermore, the resin may, for example, contain acrylate resins (also known as acrylic resins), such as urethane acrylate resins. Additionally, the resin may, for example, be a copolymer of a curable urethane acrylate resin and a multifunctional acrylate.

[0089] The aforementioned resin material may contain, for example, oligomers and monomers having functional groups. For example, the resin forming the third hard coating 103 may be a copolymer of the aforementioned oligomers having functional groups and the aforementioned monomers. The aforementioned oligomers having functional groups are not particularly limited, and examples include, for instance, cured urethane acrylate resins. Examples of cured urethane acrylate resins include, for instance, the trade name "UV-1700TL" and the trade name "UT-7314" manufactured by Mitsubishi Chemical Corporation. The aforementioned monomers are not particularly limited, and examples include, for instance, polyfunctional acrylates. Examples of polyfunctional acrylates include, for instance, the trade name "M-920" manufactured by Toa Synthetic Co., Ltd.

[0090] There are no particular limitations on the solvents mentioned above; various solvents can be used, either alone or in combination. For example, the most suitable solvent type and solvent ratio can be selected appropriately based on the composition of the resin, the type and content of the nano-silica particles and the thixotropic agent. Examples of solvents include: alcohols such as methanol, ethanol, isopropanol (IPA), butanol, tert-butanol (TBA), and 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone; esters such as methyl acetate, ethyl acetate, and butyl acetate; ethers such as diisopropyl ether and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; cellosolves such as ethyl and butyl cellosolves; aliphatic hydrocarbons such as hexane, heptane, and octane; and aromatic hydrocarbons such as benzene, toluene, and xylene. Furthermore, the solvents mentioned above may include hydrocarbon solvents and ketone solvents. For example, the hydrocarbon solvents mentioned above can be aromatic hydrocarbons. The aforementioned aromatic hydrocarbon may be, for example, at least one selected from the group consisting of toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, and benzene. The aforementioned ketone solvent may be, for example, at least one selected from the group consisting of cyclopentanone and acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, cyclohexanone, isophorone, and acetophenone. For example, to dissolve the thixotropic agent (e.g., thickener), the solvent preferably contains the aforementioned hydrocarbon solvent (e.g., toluene). The aforementioned solvent may be, for example, a solvent obtained by mixing the aforementioned hydrocarbon solvent and the aforementioned ketone solvent in a mass ratio of 90:10 to 10:90. The mass ratio of the aforementioned hydrocarbon solvent to the aforementioned ketone solvent may be, for example, 80:20 to 20:80, 70:30 to 30:70, or 40:60 to 60:40, etc. In this case, for example, the aforementioned hydrocarbon solvent may be toluene and the aforementioned ketone solvent may be methyl ethyl ketone. In addition, the solvent may contain, for example, toluene and at least one selected from the group consisting of ethyl acetate, butyl acetate, IPA, methyl isobutyl ketone, methyl ethyl ketone, methanol, ethanol, and TBA.

[0091] For example, when using an acrylic film as the substrate 110 to form an intermediate layer (penetration layer), a good solvent relative to the acrylic film (acrylic resin) can be suitably used. As such a solvent, for example, as described above, it can be a solvent comprising a hydrocarbon solvent and a ketone solvent. The hydrocarbon solvent can be, for example, an aromatic hydrocarbon. The aromatic hydrocarbon can be, for example, at least one selected from the group consisting of toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, and benzene. The ketone solvent can be, for example, at least one selected from the group consisting of cyclopentanone, acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, cyclohexanone, isophorone, and acetophenone. The solvent can be, for example, a solvent obtained by mixing the hydrocarbon solvent and the ketone solvent at a mass ratio of 90:10 to 10:90. The mass ratio of the hydrocarbon solvent to the ketone solvent can be, for example, 80:20 to 20:80, 70:30 to 30:70, or 40:60 to 60:40, etc. In this case, for example, the hydrocarbon solvent can be toluene and the ketone solvent can be methyl ethyl ketone.

[0092] For example, when using cellulose triacetate (TAC) as the base material 110, the solvent is not particularly limited and can include, for example, ethyl acetate, methyl ethyl ketone, MIBK (methyl isobutyl ketone), cyclopentanone, etc. Only one solvent can be used, or multiple solvents can be used in combination. In this case, the solvent can be, for example, a mixture of MIBK and cyclopentanone. The mixing ratio of MIBK and cyclopentanone is not particularly limited, and can be, for example, by mass ratio, 90:10 to 10:90, 80:20 to 20:80, or 70:30 to 30:70.

[0093] Furthermore, by appropriately selecting solvents, thixotropic properties can be well exhibited in anti-glare hard coating forming materials (coating solutions) when thixotropic agents are present. For example, when using organoclay, toluene and xylene can be used alone or in combination; when using oxidized polyolefins, methyl ethyl ketone, ethyl acetate, and propylene glycol monomethyl ether can be used alone or in combination; and when using modified urea, butyl acetate and methyl isobutyl ketone can be used alone or in combination.

[0094] Various leveling agents can be added to the aforementioned third hard coating forming material. For example, fluorine-based or silicone-based leveling agents can be used to prevent uneven coating (homogenization of the coating surface). In this invention, the leveling agent can be appropriately selected depending on whether the surface of the third hard coating requires antifouling properties, or whether an antireflective layer (low refractive index layer) or a layer containing an interlayer filler is formed on the third hard coating as one of the other layers described above.

[0095] The amount of the leveling agent mixed with the resin is, for example, 5 parts by weight or less, preferably in the range of 0.01 to 5 parts by weight, relative to 100 parts by weight of the resin.

[0096] In the aforementioned third hard coating forming material, pigments, fillers, dispersants, plasticizers, UV absorbers, surfactants, antifouling agents, antioxidants, etc., may also be added as needed, within a range that does not impair performance. These additives may be used individually or in combination of two or more.

[0097] The aforementioned third hard coating forming material may, for example, use a known photopolymerization initiator as described in Japanese Patent Application Publication No. 2008-88309.

[0098] As a method for forming a coating film by coating the aforementioned third hard coating forming material (coating liquid) onto the substrate 110, coating methods such as spray coating, mold coating, spray coating, gravure coating, roller coating, and bar coating can be used.

[0099] Next, the coating is dried and cured as described above to form the third hard coating layer. The drying process can be, for example, natural drying, forced air drying, heat drying, or a combination of these methods.

[0100] The drying temperature of the aforementioned third hard coating forming material (coating liquid) can, for example, be in the range of 30 to 200°C. The aforementioned drying temperature can be, for example, above 40°C, above 50°C, above 60°C, above 70°C, above 80°C, above 90°C, or above 100°C, and can be below 190°C, below 180°C, below 170°C, below 160°C, below 150°C, below 140°C, below 135°C, below 130°C, below 120°C, or below 110°C. The drying time is not particularly limited, and can, for example, be above 30 seconds, above 40 seconds, above 50 seconds, or above 60 seconds, and can be below 150 seconds, below 130 seconds, below 110 seconds, or below 90 seconds.

[0101] The curing method for the above coating is not particularly limited, but ultraviolet curing is preferred. The irradiation dose from the energy source, measured as the cumulative exposure at a UV wavelength of 365 nm, is preferably 50–500 mJ / cm². 2 If the radiation dose is 50 mJ / cm 2 In this way, curing can proceed easily and completely, and the hardness of the resulting third hard coating can be easily increased. Additionally, if the value is 500 mJ / cm... 2 The following can prevent the coloring of the formed third hard coating.

[0102] If done as described above, it can be manufactured. Figure 3 The laminate of substrate 110 and third hard coating 103 shown in (a).

[0103] Next, as Figure 3As shown in (b), a protective film 120 is laminated on the surface of the third hard coating layer 103 (the surface opposite to the substrate 110) (protective film lamination process). This protective film lamination process is not essential in this invention and may or may not be performed. The protective film 120 is not particularly limited and may be, for example, a polyethylene film, a polyester film, a PET film, or, for example, the "SPV" series manufactured by Nitto Denko Corporation. Although not shown in the illustration, an adhesive layer may be formed on the surface of the third hard coating layer 103, and the protective film 120 may be attached using this adhesive layer. Furthermore, the protective film 120 can be used to protect the adhesive layer from being exposed. Additionally, the protective film 120 may be peeled off just before using the adhesive layer, and the hard coating film of this invention may be added to the substrate using the adhesive layer. The substrate may be, for example, a component other than the hard coating film of this invention in an image display device. The method of forming the adhesive layer is not particularly limited, and conventional methods may be suitable, such as coating.

[0104] The aforementioned adhesive layer may be, for example, an adhesive layer formed by an adhesive (adhesive composition). In this invention, the aforementioned adhesive layer may be, for example, a layer that allows the protective film 120 to be peeled off from the third hard coating layer 103. The thickness of the aforementioned adhesive layer is not particularly limited, and may be, for example, 5 μm or more, 10 μm or more, 20 μm or more, or 25 μm or more, or may be, for example, 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, or 20 μm or less. The aforementioned adhesive is not particularly limited, and examples include (meth)acrylic polymers. These may be dissolved or dispersed in a solvent to form a solution or dispersion, and used as the aforementioned adhesive (adhesive composition). Examples of the aforementioned solvents include ethyl acetate, and only one may be used, or multiple may be used in combination. The concentration of the solute or dispersed substance (e.g., the aforementioned acrylic polymer) in the aforementioned solution or dispersion may be, for example, 10% by mass or more, or 15% by mass or more, or for example, 60% by mass or less, 50% by mass or less, 40% by mass or less, or 25% by mass or less. It should be noted that, in this invention, "(meth)acrylic acid polymer" refers to a polymer or copolymer of at least one monomer selected from (meth)acrylic acid, (meth)acrylate, and (meth)acrylamide. Furthermore, in this invention, (meth)acrylic acid refers to "at least one of acrylic acid and methacrylic acid," and "(meth)acrylate" refers to "at least one of acrylate and methacrylate." Examples of the aforementioned (meth)acrylates include, for example, straight-chain or branched alkyl esters of (meth)acrylic acid. In the aforementioned straight-chain or branched alkyl esters of (meth)acrylic acid, the number of carbon atoms in the alkyl group can be, for example, 1 or more, 2 or more, 3 or more, or 4 or more, and for example, 18 or less, 16 or less, 14 or less, 12 or less, 10 or less, or 8 or less. The aforementioned alkyl group can be substituted by one or more substituents, or it can be unsubstituted. Examples of the aforementioned substituents include, for example, hydroxyl groups, and when multiple substituents are present, they can be the same or different. Specific examples of the aforementioned (meth)acrylates include, for example, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, and 4-hydroxybutyl acrylate. In addition, one type of adhesive may be used, or multiple types may be used in combination.

[0105] Furthermore, such as Figure 3 As shown in (c), a second hard coating 102 is formed on the other side of the substrate 110 (the side opposite to the third hard coating 103) (the second hard coating formation process). Furthermore, thereafter... Figure 3As shown in (d), the first hard coating 101 is formed on the surface of the second hard coating 102 (the surface opposite to the substrate 110) (first hard coating formation step). The second and first hard coating formation steps are not particularly limited; for example, except that the composition of the coating liquid (hard coating forming material), the thickness of the hard coating, etc., are appropriately set according to the second and first hard coatings 102 and 101, they can be performed in the same manner as the third hard coating formation step described above. Specifically, for example, a coating liquid containing nano-silica particles is used, and the weight-average particle size of the nano-silica particles is appropriately set according to the second and first hard coatings 102 and 101. Other conditions can also be appropriately set according to the second and first hard coatings 102 and 101. Furthermore, for example, when the hard coating film of the present invention is used as an anti-glare film (anti-glare hard coating film), the surface of the first hard coating 101 can be formed with unevenness. The method of forming this unevenness is not particularly limited; for example, a conventional method can be used.

[0106] The hard-coated film of the present invention can be manufactured as described above. However, as described above, this manufacturing method is illustrative, and the manufacturing method of the hard-coated film of the present invention is not limited thereto. For example, as described above, the hard-coated film of the present invention may include layers other than the substrate, the first hard coating layer, the second hard coating layer, and the third hard coating layer. Therefore, the manufacturing method of the hard-coated film of the present invention may further include the step of forming the other layers. More specifically, for example, as described above, an anti-reflective layer may be formed on the outer side of the first hard coating layer (opposite to the second hard coating layer). The method for forming the anti-reflective layer is not particularly limited; for example, conventional methods can be used.

[0107] Furthermore, the manufacturing method of the hard-coated film of the present invention can be, for example, a continuous manufacturing method. Specifically, for example, the manufacturing method of the hard-coated film of the present invention can be a manufacturing method in which the substrate is in the shape of a strip, and the third hard coating layer forming step, the second hard coating layer forming step, the first hard coating layer forming step, and other steps performed as needed are continuously performed while the substrate is being conveyed. More specifically, for example, the long strip-shaped substrate can be in the shape of a roll, and the manufacturing method of the hard-coated film of the present invention can be carried out while the substrate is being unloaded from the roll.

[0108] [3. Hard-coated thin films, optical components, and image display devices]

[0109] The hard coating film of the present invention is not particularly limited. For example, as described above, it can be a transparent film or an anti-glare film (anti-glare hard coating film).

[0110] The optical components of this invention are not particularly limited; for example, they can be polarizing plates. The polarizing plates themselves are also not particularly limited; for example, they may include the anti-glare film and polarizing element of this invention, and may also include other constituent elements. The constituent elements of the polarizing plate can be bonded together, for example, using adhesives or bonding agents.

[0111] The image display device of the present invention is not particularly limited and can be any image display device, such as liquid crystal display device, organic EL display device, inorganic EL display device, plasma display device, etc.

[0112] The configuration of the image display device of the present invention is not particularly limited, and for example, it can be the same as that of a conventional image display device. For example, in the case of an LCD, it can be manufactured by appropriately assembling various components such as liquid crystal cells, optical components such as polarizing plates, and illumination systems (backlights, etc.) used as needed, and incorporating them into driving circuits.

[0113] The image display device of the present invention has no particularly limited application and can be used for any purpose. Examples of its applications include, for instance, personal computer monitors, laptops, tablets, smartphones, copiers and other OA equipment, mobile phones, watches, digital cameras, portable information terminals (PDAs), portable game consoles and other portable devices, cameras, televisions, microwave ovens and other household electrical appliances, rearview monitors, car navigation system monitors, car audio systems and other in-vehicle equipment, commercial store information monitors and other display equipment, surveillance monitors and other security equipment, nursing monitors, medical monitors and other nursing and medical equipment, smart glasses, VR devices, etc. The image display device of the present invention can, for example, be an image display device with camera functionality. In this case, for example, as described above, the transparent layer in the hard-coated film of the present invention can be a transparent layer for the camera aperture of the image display device. According to the present invention, as described above, a hard-coated film can be provided without compromising the transparency of the transparent layer, thus, for example, an image display device can be provided without compromising the image quality of the camera image.

[0114] Example

[0115] The embodiments and comparative examples of the present invention will now be described together. However, the present invention is not limited by the following embodiments and comparative examples.

[0116] It should be noted that, in the following examples and comparative examples, the number of parts of substances is by mass (parts by weight) unless otherwise specified.

[0117] In the following examples and comparative examples, the first hard coating forming material, the second hard coating forming material and the third hard coating forming material are prepared according to the following composition.

[0118] [First Hard Coating Forming Material]

[0119] 100 parts by weight of a multifunctional acrylate (trade name "NC035", manufactured by Arakawa Chemical Industry Co., Ltd.) containing nano-silica with a weight average particle size of 40 nm and 2 parts by weight of a leveling agent (trade name "LE-303", manufactured by Shin-Etsu Chemical Industry Co., Ltd.) were diluted with cyclopentanone as a diluent to a solid content concentration of 35% by weight. This was used as the first hard coating forming material.

[0120] [Second hard coating forming material]

[0121] 100 parts by weight of a multifunctional acrylate (trade name "Opstar Z7540", manufactured by Arakawa Chemical Industry Co., Ltd.) containing nano-silica with a weight average particle size of 10 nm and 2 parts by weight of a leveling agent (trade name "LE-303", manufactured by Shin-Etsu Chemical Industry Co., Ltd.) were diluted with methyl ethyl ketone as a diluent to a solid content of 55% by weight. This was used as a second hard coating forming material.

[0122] [Third hard coating forming material (without nano-silica particles)]

[0123] 100 parts by weight of multifunctional acrylate (trade name "VISCOAT#300", manufactured by Osaka Organic Chemicals Co., Ltd.) and 3 parts by weight of photopolymerization initiator (trade name "OMNIRAD907", manufactured by BASF) were diluted with methyl ethyl ketone as a diluent to a solid content of 55% by weight. This was used as a third hard coating forming material (in the absence of nano-silica particles).

[0124] [Third hard coating forming material (in the case of nano-silica particles)]

[0125] The third hard coating forming material (in the case of nano-silica particles) uses the same material as the second hard coating forming material described above.

[0126] [Example 1]

[0127] pass Figure 3 The manufacturing method described herein is as follows: First, a TAC substrate (manufactured by Konica Minolta Co., Ltd., trade name "KC8UA") with a thickness of 80 μm is prepared as the substrate. Next, the third hard coating material (without nano-silica particles) described above is coated onto one side of the substrate, and dried in an oven at 60°C for 60 seconds to form a coating film. The film is then irradiated using a high-pressure mercury lamp with a cumulative light dose of 300 mJ / cm². 2The coating was cured by irradiating it with ultraviolet light at a wavelength of 365 nm, thereby forming a third hard coating layer. It should be noted that in this embodiment, the third hard coating forming material was applied with a thickness of 5 μm (in the absence of nano-silica particles). A protective film (manufactured by Toray Industries, Inc., trade name "TORETEC-7832C") was further attached to the surface of the formed third hard coating opposite to the substrate.

[0128] Next, the second hard coating forming material is applied to the surface of the substrate opposite to the surface where the third hard coating is formed, and dried in an oven at 60°C for 60 seconds to form a coating film. A high-pressure mercury lamp is used to irradiate the surface with a cumulative light dose of 300 mJ / cm². 2 The coating is cured by irradiating it with ultraviolet light at a wavelength of 365 nm, thereby forming a second hard coating. It should be noted that in this embodiment, the above-mentioned second hard coating forming material is applied with a thickness of 10 μm.

[0129] Then, the first hard coating forming material is applied to the surface of the second hard coating opposite to the substrate, and dried in an oven at 60°C for 60 seconds to form a coating film. A high-pressure mercury lamp is used to irradiate the surface with a cumulative light dose of 300 mJ / cm². 2 The coating is cured by irradiating it with ultraviolet light at a wavelength of 365 nm, thereby forming the first hard coating layer. It should be noted that in this embodiment, the first hard coating layer forming material is applied with a thickness of 5 μm.

[0130] The hard coating film of this embodiment (Example 1) is manufactured as described above. It should be noted that when the hard coating film of this embodiment and the following embodiments and comparative examples is attached to a glass plate or the like described later, the protective film is peeled off from the third hard coating layer.

[0131] [Example 2]

[0132] The thickness of the second hard coating layer was changed to 20 μm, and the thickness of the third hard coating layer was changed to 10 μm. Otherwise, the hard coating film of this embodiment (Example 2) was manufactured in the same manner as in Example 1.

[0133] [Example 3]

[0134] The thickness of the first hard coating layer was changed to 10 μm, and the thickness of the third hard coating layer was changed to 10 μm. Otherwise, the hard coating film of this embodiment (Example 3) was manufactured in the same manner as in Example 1.

[0135] [Example 4]

[0136] The thickness of the first hard coating layer was changed to 10 μm, the thickness of the second hard coating layer was changed to 20 μm, and the thickness of the third hard coating layer was changed to 15 μm. Otherwise, the hard coating film of this embodiment (Example 4) was manufactured in the same manner as in Example 1.

[0137] [Example 5]

[0138] The third hard coating material containing nano-silica particles was formed by replacing the third hard coating material (without nano-silica particles) with the third hard coating material (with nano-silica particles). The thickness of the third hard coating material was changed to 15 μm. Otherwise, the hard coating film of this embodiment (Example 5) was manufactured in the same manner as in Example 1.

[0139] [Example 6]

[0140] The thickness of the second hard coating layer was changed to 20 μm, and the thickness of the third hard coating layer was changed to 25 μm. Otherwise, the hard coating film of this embodiment (Example 6) was manufactured in the same manner as in Example 5.

[0141] [Comparative Example 1]

[0142] The thickness of the first hard coating was changed to 20 μm, and the second and third hard coatings were not formed. Otherwise, the hard coating film of this comparative example (Comparative Example 1) was manufactured in the same manner as in Example 1.

[0143] [Comparative Example 2]

[0144] The first hard coating layer was not formed, but otherwise the hard coating film of this comparative example (comparative example 2) was manufactured in the same manner as in Example 5.

[0145] [Comparative Example 3]

[0146] The thicknesses of the second and third hard coating layers were changed to 20 μm, and the hard coating film of this comparative example (comparative example 3) was manufactured in the same manner as comparative example 2.

[0147] [Formation of the anti-reflective layer]

[0148] On the surface opposite to the substrate of the first hard coating layer (or, in the case of no first hard coating layer, on the second hard coating layer) in the hard coating films of the above embodiments and comparative examples, an anti-reflective layer (DRY-AR layer) is formed by the following method. First, an Nb target is placed in a magnetron sputtering apparatus, and reactive sputtering is performed to form a first Nb₂O₅ layer (12 nm thick, refractive index 2.34) on the first hard coating layer (or, in the case of no first hard coating layer, on the second hard coating layer). Next, a Si target is placed in a magnetron sputtering apparatus, and reactive sputtering is performed to form a first SiO₂ layer (39 nm thick, refractive index 1.46) on the first Nb₂O₅ layer. Next, a second Nb₂O₅ layer (119 nm thick, refractive index 2.34) is formed on the first SiO₂ layer by the same method as the formation of the first Nb₂O₅ layer. Furthermore, on the aforementioned second Nb₂O₅ layer, a second SiO₂ layer (thickness: 78 nm, refractive index 1.46) is formed using the same method as the formation of the first SiO₂ layer. This results in an anti-reflective layer (DRY-AR layer) with two Nb₂O₅ layers and two SiO₂ layers stacked alternately.

[0149] [Methods for measuring thickness]

[0150] The thickness of each layer of the hard-coated film was determined by observing the cross-section using TEM (transmission electron microscopy).

[0151] Methods for measuring pencil hardness

[0152] The pencil hardness was measured based on the pencil hardness test according to JIS K 5600-5-4, except that the load was set to 750g. Furthermore, as described below, the pencil hardness of the hard-coated films of the above embodiments and comparative examples was measured under the three conditions described in (1) to (3) below. It should be noted that the thickness of the glass plate in (1) to (3) below is 1.5mm. Additionally, the 25μm thick adhesive layer in (2) below was formed using Nitto Denko Corporation's trade name "CS9821UD" as the adhesive. The 5μm thick adhesive layer in (3) below was formed using Nitto Denko Corporation's trade name "Monkey" as the adhesive.

[0153] (1) The glass plate and the third hard coating are bonded together with an adhesive layer with a thickness of 25 μm.

[0154] (2) The glass plate and the third hard coating are bonded together with an adhesive layer of 5 μm thickness.

[0155] (3) The third hard coating is directly bonded without setting an adhesive layer on the glass plate.

[0156] [Methods for determining and evaluating curl]

[0157] For the hard-coated films of the above embodiments and comparative examples, a square with a side length of 15 cm was cut from the center relative to the width direction of the preform, and this square was used as a test sample. When cutting the test sample, the diagonal of the square was aligned with both the MD direction and the TD direction. It should be noted that the MD direction refers to the direction parallel to the transport direction of the substrate (the long side direction of the substrate) during the manufacture of the hard-coated film on the surface of the substrate. The TD direction refers to the direction perpendicular to the MD direction on the surface of the substrate. A rod-shaped weight was placed along the diagonal of the MD direction of the test sample and pressed down. The maximum height of the warp at the end of the test sample along the TD direction [mm] was measured and evaluated as the size of the curl in the TD direction. Similarly, a rod-shaped weight was placed along the diagonal of the TD direction of the test sample and pressed down. The maximum height of the warp at the end of the test sample along the MD direction [mm] was measured and evaluated as the size of the curl in the MD direction. The greater the height of the warp, the greater the curl.

[0158] [Methods for determining and evaluating the adhesion of anti-reflective layers]

[0159] The hard-coated films of the above-described embodiments and comparative examples, which have formed anti-reflective layers, were cut into 5cm squares. The substrate side of each square was adhered to a 1.5mm thick glass plate using an adhesive manufactured by Nitto Denko Corporation, trade name "CS9821UD". The plates were then irradiated with ultraviolet light using a metal halide lamp. The irradiation conditions were set to an ambient temperature of 55°C, an ambient humidity of 45%, and a light intensity of 830W / m². 2 The irradiation time was 240 hours, and the BPT temperature was 85°C. After UV irradiation, 1-2 mL of isopropyl alcohol was dropped onto the antireflective layer. A loaded cloth (trade name "Anticon Gold," manufactured by Contec Group) was then slid across the layer, and the presence of scratches on the antireflective layer was confirmed visually and under a microscope (100x magnification). If no scratches were found on the antireflective layer through visual inspection and microscopic examination, the adhesion was rated as ○. If scratches were visible in at least one of the conditions, the adhesion was rated as ×.

[0160] The evaluation results of the composition and properties of the hard coating films in the above embodiments and comparative examples are shown in Tables 1 and 2 below. It should be noted that in Tables 1 and 2 below, "HC thickness" represents the thickness of each hard coating layer. "Paste" represents the adhesive layer used in bonding the glass plate to the third hard coating layer. "MD" represents the MD direction, that is, the direction parallel to the transport direction of the substrate (long side direction of the substrate) during the manufacture of the hard coating film on the surface of the substrate. "TD" represents the TD direction, that is, the direction perpendicular to the MD direction on the surface of the substrate.

[0161] It should be noted that, as shown in Tables 1 and 2 below, the third hard coating of the hard coatings in Examples 1-4 does not contain nano-silica particles, in order to... Figure 1 The hard coating film 100a of (a) has the same structure. The third hard coating of the hard coatings in Examples 5-6 contains nano-silica particles, which is similar to... Figure 1 The hard coating film 100b of (b) has the same structure. Furthermore, as shown in Tables 1 and 2 below, the pencil hardness was measured for three cases: (1) the glass plate and the third hard coating are bonded together with an adhesive layer of 25 μm thickness, (2) the glass plate and the third hard coating are bonded together with an adhesive layer of 5 μm thickness, and (3) the third hard coating is directly bonded together without an adhesive layer on the glass plate. Figure 2 Their composition is shown in the sectional views (a) to (d). Figure 2 (a) and (b) are examples of using the hard coating films of Examples 1 to 4 (the third hard coating layer 103 does not contain nano-silica particles). Figure 2 (a) is an example in which the third hard coating 103 is directly bonded to the glass plate 210 without the use of an adhesive. Figure 2 (b) is an example of bonding the third hard coating 103 directly to the glass plate 210 using adhesive 220. Figure 2 (c) and (d) are examples of using the hard coating film of Examples 5-6 (the third hard coating 103 contains nano-silica particles 103P). Figure 2 (c) is an example in which the third hard coating 103 is directly bonded to the glass plate 210 without the use of an adhesive. Figure 2 (d) is an example of bonding the third hard coating 103 directly to the glass plate 210 using adhesive 220.

[0162] Table 1

[0163]

[0164] Table 2

[0165]

[0166] As shown in Tables 1 and 2 above, the hard coating films of Examples 1 to 6 all exhibited high hardness (pencil hardness), suppressed curling (the curling at the end of the hard coating film was 0 mm in the curling test), and had high adhesion between the visual recognition side surface and other layers (DRY-AR layer). In particular, the hard coating films of Examples 1 to 4, whose third hard coating layer did not contain nano-silica particles, maintained high hardness (pencil hardness) even when bonded to a glass plate using an adhesive layer with a thickness of 25 μm. In contrast, Comparative Example 1, which did not have a second or third hard coating layer, had low hardness (pencil hardness) and curled, resulting in a cylindrical shape. On the other hand, Comparative Examples 2 and 3, which had a second and third hard coating layer but not a first hard coating layer, exhibited high hardness (pencil hardness) and suppressed curling, but had low adhesion between the visual recognition side surface and other layers (DRY-AR layer).

[0167] Industrial availability

[0168] As explained above, according to the present invention, a hard-coated film with high hardness, suppressed curling, and high adhesion between the visual recognition side surface and other layers, optical components, and image display devices can be provided. The hard-coated film of the present invention, as described above, can be used as both a transparent film and an anti-glare film (anti-glare hard-coated film), and can be used in a wide variety of optical components and image display devices, thus possessing significant industrial application value.

[0169] This application claims priority based on Japanese Special Application No. 2021-059320, filed on March 31, 2021, the entire contents of which are hereby incorporated.

Claims

1. A hard-coated film, characterized by comprising: It includes a substrate, a first hard coating, a second hard coating, and a third hard coating. The first hard coating, the second hard coating, the substrate, and the third hard coating are layered in this order, starting from the visual recognition side. The first hard coating and the second hard coating each contain nano-silica particles. The weight-average particle size of the nano-silica particles contained in the first hard coating is greater than that of the nano-silica particles contained in the second hard coating. The third hard coating does not contain nano-silica particles.

2. The hard-coated film according to claim 1, wherein The thickness of the third hard coating is less than the combined thickness of the first hard coating and the second hard coating.

3. The hard-coated film according to claim 1 or 2, wherein, The weight-average particle size of the nano-silica particles contained in the first hard coating is 30-50 nm. The weight-average particle size of the nano-silica particles contained in the second hard coating is 5-30 nm.

4. The hard-coated film according to claim 1 or 2, wherein The overall transmittance of the hard coating film at a wavelength of 550 nm is over 90%.

5. An optical component comprising a hard-coated thin film according to any one of claims 1 to 4.

6. The optical component according to claim 5, wherein it is a polarizing plate.

7. An image display device comprising a hard-coated thin film according to any one of claims 1 to 4, or an optical component according to claim 5 or 6.

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