Hard coat film

Abstract

The present invention provides a hard coat film that exhibits excellent initial adhesion and lightfastness between an easily adhesive layer and a hard coat layer, which are provided on a cycloolefin polymer film. [Solution] This hard coat film is constructed by laminating a hard coat layer containing an ultraviolet-curable resin, an ultraviolet absorber, and a dye on at least one side of a cycloolefin polymer film via an easy-adhesion layer made of an ultraviolet-curable resin containing inorganic fine particles. The ultraviolet absorber is a combination of a benzotriazole-based ultraviolet absorber and a hydroxyphenyltriazine-based ultraviolet absorber, the maximum absorption wavelength (λmax) of the ultraviolet absorber is in the range of 350nm to 380nm, the maximum absorption wavelength (λmax) of the dye is in the range of 395nm to 415nm, and the b* value is 7.0 or less. Furthermore, the light reduction rate at 350 to 410nm is 95.0% or more, the light reduction rate at 420nm is 75.0% or less, the light reduction rate at 430nm is 30.0% or less, the light reduction rate at 440nm is 7.0% or less, and the light reduction rate at 450nm is 2.0% or less.

Description

[Technical Field]

[0001] The present invention relates to a hard coat film used in optical components. More specifically, it relates to a hard coat film that can be used as a protective film for panel displays such as organic electroluminescent (EL) displays, liquid crystal displays (LCDs), and plasma displays, as well as display device components such as touch panels. [Background technology]

[0002] For example, the display surfaces of displays such as organic electroluminescent (EL) displays and liquid crystal displays (LCDs) are required to be scratch-resistant to prevent damage during handling and reduce visibility. Therefore, it is common practice to use a hard-coat film, which has a hard-coat layer on a base film, to provide scratch resistance to the display surface of a display.

[0003] In recent years, with the trend towards thinner and lighter displays, the constituent materials have also been thinned. For example, the hard coat film used in the polarizing plates of displays has also been thinned. As the hard coat film becomes thinner, the dimensional stability of the polarizing plate decreases, leading to problems such as the polarizing plate warping (curling) under high temperature or high humidity conditions. Therefore, as a way to solve this problem, a cycloolefin polymer film with low moisture absorption (low moisture permeability) and excellent dimensional stability is used as the base film for the hard coat film.

[0004] However, unlike acrylic and polyester films, this cycloolefin polymer film has fewer polar groups on its surface (it is non-polar). Therefore, when using cycloolefin polymer film as a substrate, there is a problem in that conventional UV-curing hard coat paints, such as those made from acrylic resins, do not adhere to it.

[0005] To improve the adhesion between the cycloolefin polymer film and the hard coat layer, several methods are generally known, including surface modification (hydrophilization) of the cycloolefin polymer film by corona treatment or plasma treatment before hard coat application, forming a compatible layer at the interface between the hard coat layer and the cycloolefin polymer film substrate using hydrocarbon solvents such as toluene that dissolve the cycloolefin polymer film to obtain adhesion, and providing an anchor layer on the cycloolefin polymer film (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2006-110875 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, adhesion achieved by surface modification (hydrophilization) of cycloolefin polymer films lacks stability, and even if 100% initial adhesion is ensured, adhesion failures are particularly likely to occur over time, resulting in a lack of durable adhesion.

[0008] Furthermore, the method of forming a compatible layer has the problem that excessive load is placed on the cycloolefin polymer film substrate during hard coat application, leading to chemical cracking of the cycloolefin polymer film substrate due to solvent erosion. In particular, the frequency of these chemical cracks tends to increase as the cycloolefin polymer film substrate becomes thinner.

[0009] Furthermore, while the method of providing an anchor layer generally involves using a modified polyolefin resin for the anchor layer, modified polyolefin resins readily dissolve in hydrocarbon solvents such as toluene. Therefore, hydrocarbon solvents such as toluene cannot be used in the hard coat paint applied on the anchor layer, which presents a challenge in paint design.

[0010] On the other hand, to improve the durability (light resistance) of the light-emitting elements in organic EL displays, UV protection is necessary on the display surface. While general UV protection performance was based on the transmittance at a wavelength of 380nm, recently, transmittance in the 390nm to 410nm range has become the standard for protecting the light-emitting elements.

[0011] While UV absorbers and dyes are known for adjusting transmittance in the 390nm to 410nm range, hydrocarbon solvents such as toluene are suitable solvents for all of them. In other words, hard coat coatings containing UV absorbers and dyes to adjust transmittance in the 390nm to 410nm range, intended to improve the durability (light resistance) of light-emitting elements in organic EL displays using hard coat films, require the use of hydrocarbon solvents such as toluene as the solvent in the hard coat coating, considering the solubility of the materials. Therefore, applying these coatings to cycloolefin polymer film substrates, especially thin cycloolefin polymer film substrates, is difficult due to concerns about the occurrence of chemical cracks.

[0012] Therefore, the object of the present invention is, firstly, to provide a hard coat film that uses a cycloolefin polymer film as a base material and has excellent adhesion (initial adhesion and light resistance) between the easy-adhesion layer and the hard coat layer provided on the base material film; secondly, to provide a hard coat film in which the easy-adhesion layer provided on the base material film has good solvent resistance to hydrocarbon solvents, and even when a hard coat paint containing a hydrocarbon solvent is directly applied to the easy-adhesion layer, a good coating appearance can be obtained; and thirdly, when used as a protective film for the surface of an organic EL display, to provide a hard coat film that can improve the durability (light resistance) of the light-emitting elements of the organic EL display without adversely affecting the color and brightness of the display of the organic EL display, and can suppress the deterioration of the display of the organic EL display. [Means for solving the problem]

[0013] The present inventors conducted diligent studies to solve the above problems and found that the above problems can be solved by an invention having the following configuration. In other words, the present invention has the following configuration.

[0014] (First invention) A hard coat film is provided in which a hard coat layer containing an ultraviolet-curable resin, an ultraviolet absorber and a dye is laminated on at least one side of a cycloolefin polymer film with a thickness of 50 μm or less, via an easy-adhesion layer made of an ultraviolet-curable resin containing inorganic fine particles, and satisfies the following condition (A), and the light reduction rate (%) at each wavelength calculated by the following formula 1 satisfies the following conditions (B) to (L). (A) The b* value is 7.0 or less. Equation 1) Light reduction rate (%) at each wavelength = (Transmittance of the cycloolefin polymer film alone at that wavelength - Transmittance of the hard coat film at that wavelength) / Transmittance of the cycloolefin polymer film alone at that wavelength (B) The light reduction rate at a wavelength of 350 nm is 95.0% or more. (C) The light reduction rate at a wavelength of 360 nm is 95.0% or more. (D) The light reduction rate at a wavelength of 370 nm is 95.0% or more. (E) The light reduction rate at a wavelength of 380 nm is 95.0% or more. (F) The light reduction rate at a wavelength of 390 nm is 95.0% or more. (G) The light reduction rate at a wavelength of 400 nm is 95.0% or more. (H) The light reduction rate at a wavelength of 410 nm is 95.0% or more. (I) The light reduction rate at a wavelength of 420 nm is 75.0% or less. (J) The light reduction rate at a wavelength of 430 nm is 30.0% or less. (K) The light reduction rate at a wavelength of 440 nm is 7.0% or less. (L) The light reduction rate at a wavelength of 450 nm is 2.0% or less. <�

[0015] (Second Invention) For the hard coat film, in an environment of a temperature of 63°C and a relative humidity of 50%, with a radiation irradiance of 500 W / m 2 and ultraviolet rays are irradiated for 100 hours (light resistance test), the absolute value of the change rate (Δ%) of the light transmittance at each wavelength calculated by the following formula 2 satisfies the following conditions (M) to (W), which is the hard coat film according to the first invention. Formula 2) The change rate (Δ%) of the light transmittance at each wavelength = the transmittance at that wavelength after the light resistance test of the hard coat film - the transmittance at that wavelength before the light resistance test of the hard coat film (M) The absolute value of the change rate of the light transmittance at a wavelength of 350 nm is 1.0% or less. (N) The absolute value of the change rate of the light transmittance at a wavelength of 360 nm is 1.0% or less. (O) The absolute value of the change rate of the light transmittance at a wavelength of 370 nm is 1.0% or less. (P) The absolute value of the change rate of the light transmittance at a wavelength of 380 nm is 1.0% or less. (Q) The absolute value of the change rate of the light transmittance at a wavelength of 390 nm is 5.0% or less. (R) The absolute value of the change rate of the light transmittance at a wavelength of 400 nm is 10.0% or less. (S) The absolute value of the change rate of the light transmittance at a wavelength of 410 nm is 30.0% or less. (T) The absolute value of the change rate of the light transmittance at a wavelength of 420 nm is 30.0% or less. (U) The absolute value of the change rate of the light transmittance at a wavelength of 430 nm is 10.0% or less. (V) The absolute value of the change rate of the light transmittance at a wavelength of 440 nm is 5.0% or less. (W) The absolute value of the change rate of the light transmittance at a wavelength of 450 nm is 5.0% or less.

[0016] (The third invention) The hard coat film according to the first or second invention, wherein the maximum absorption wavelength (λmax) of the ultraviolet absorber is in the range of 350 nm to 380 nm, and the maximum absorption wavelength (λmax) of the dye is in the range of 395 nm to 415 nm.

[0017] (The fourth invention) The hard coat film according to any one of the first to third inventions, wherein the ultraviolet absorber is a combination of a benzotriazole-based ultraviolet absorber and a hydroxyphenyltriazine-based ultraviolet absorber.

[0018] (The fifth invention) The hard coat film according to any one of the first to fourth inventions, wherein the dye is a cyanine dye. [Advantages of the invention]

[0019] According to the present invention, a hard coat film excellent in adhesion (initial adhesion and light-resistant adhesion) to an easy-adhesion layer and a hard coat layer provided on a substrate film can be provided even for a substrate such as a cycloolefin polymer-based film having few polar groups and poor adhesion. Furthermore, according to the present invention, the easy-adhesion layer provided on the base film has good solvent resistance to hydrocarbon solvents, and even when a hard coat coating containing a hydrocarbon solvent is directly applied to the easy-adhesion layer, a hard coat film with a good coating appearance can be obtained.

[0020] Furthermore, according to the present invention, when used as a protective film for the surface of an organic EL display, it is possible to provide a hard coat film that does not adversely affect the color or brightness of the display of the organic EL display, improves the durability (light resistance) of the light-emitting elements of the organic EL display, and suppresses the deterioration of the display of the organic EL display. In particular, the hard coat film of the present invention is suitable when a thin cycloolefin polymer film is used as the substrate. [Modes for carrying out the invention]

[0021] The following describes in detail embodiments for carrying out the present invention, but the present invention is not limited to the following embodiments. In this specification, unless otherwise specified, "○○~△△" means "greater than ○○ and less than or equal to △△".

[0022] As described in the first invention above, the hard coat film of the present invention is characterized in that a hard coat film is laminated on at least one side of a cycloolefin polymer film with a thickness of 50 μm or less, with an easy-adhesion layer made of an ultraviolet-curable resin containing inorganic fine particles, and a hard coat layer containing an ultraviolet-curable resin, an ultraviolet absorber, and a dye, satisfying the following condition (A), and the light reduction rate (%) at each wavelength calculated by the following formula 1 satisfies the following conditions (B) to (L). (A) The b* value is 7.0 or less. Equation 1) Light reduction rate (%) at each wavelength = (Transmittance of the cycloolefin polymer film alone at that wavelength - Transmittance of the hard coat film at that wavelength) / Transmittance of the cycloolefin polymer film alone at that wavelength (B) The light reduction rate at a wavelength of 350 nm is 95.0% or higher. (C) The light reduction rate at a wavelength of 360 nm is 95.0% or higher. (D) The light reduction rate at a wavelength of 370 nm is 95.0% or higher. (E) The light reduction rate at a wavelength of 380 nm is 95.0% or higher. (F) The light reduction rate at a wavelength of 390 nm is 95.0% or higher. (G) The light reduction rate at a wavelength of 400 nm is 95.0% or higher. (H) The light reduction rate at a wavelength of 410 nm is 95.0% or higher. (I) The light reduction rate at a wavelength of 420 nm is 75.0% or less. (J) The light reduction rate at a wavelength of 430 nm is 30.0% or less. (K) The light attenuation rate at a wavelength of 440 nm is 7.0% or less. (L) The light reduction rate at a wavelength of 450 nm is 2.0% or less. The composition of this hard coat film will be explained in detail below.

[0023] [Base film] First, let's describe the base film of the hard coat film mentioned above. In the present invention, a cycloolefin polymer film that is excellent in transparency, heat resistance, dimensional stability, low moisture absorption (low moisture permeability), low birefringence, and optical isotropy is used as the base film for the hard coat film. Specifically, the target is a cycloolefin copolymer film or cycloolefin polymer film which is a copolymer comprising at least one compound selected from norbornene compounds, monocyclic cyclic olefins, cyclic conjugated dienes, and vinyl alicyclic hydrocarbons, in which cycloolefin units are polymerized alternately or randomly in the polymer backbone and have an alicyclic structure in the molecular structure, and which can be appropriately selected and used.

[0024] Furthermore, in the present invention, the thickness of the cycloolefin polymer film is appropriately selected depending on the application, but from the viewpoint of the need for thinning of the hard coat film due to the thinning and weight reduction of displays, it is preferably 50 μm or less, and particularly preferably 30 μm or less. On the other hand, from the viewpoint of mechanical strength, handling properties, etc., it is preferably 10 μm or more.

[0025] In the present invention, when a hard coat layer is formed on one side of the cycloolefin polymer film via an easy-adhesion layer, the back surface of the cycloolefin polymer film where the hard coat layer is not formed may be a film laminated with polyethylene resin, polypropylene resin, or polyester resin as a protective layer during the production of the cycloolefin polymer film by co-extrusion, for the purpose of preventing adhesion during winding of the cycloolefin polymer film and improving the running performance of the film when forming the hard coat layer. Alternatively, it is possible to use a film to which a protective film of polyethylene resin, polypropylene resin, or polyester resin with a weakly adhesive layer formed on the back surface has been attached.

[0026] Examples of the cycloolefin polymer films mentioned above include commercially available products such as Zeonor (product name: manufactured by Nippon Zeon Co., Ltd.), Optica (product name: manufactured by Mitsui Chemicals, Inc.), Arton (product name: manufactured by JSR Corporation), and Cozec (product name: manufactured by Kurabo Industries Ltd.).

[0027] [Easy adhesive layer] Next, the easy-adhesion layer of the hard coat film described above will be explained. In the hard coat film of the present invention, the easy-adhesion layer is made of an ultraviolet-curable resin containing inorganic fine particles. In the present invention, the resin used in the easy-adhesion layer is an ultraviolet-curable resin, and is not particularly limited as long as it is a transparent resin that hardens when irradiated with ultraviolet light (hereinafter abbreviated as "UV"). For example, acrylic resins whose basic skeleton consists of polymers of acrylic acid ester or methacrylic acid ester, and urethane acrylate resins having urethane bonds formed by reacting isocyanate groups and hydroxyl groups with acrylic groups can be preferably used. In order for the easy-adhesion layer to form a three-dimensional crosslinked structure, it is preferable to use a UV-curable polyfunctional acrylate, for example, that has multiple functional groups such as (meth)acryloyloxy groups in the molecule. Specific examples of UV-curable polyfunctional acrylates having multiple (meth)acryloyloxy groups in the molecule include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane ethoxytriacrylate, glycerin propoxytriacrylate, and ditrimethylolpropane tetraacrylate. Polyfunctional acrylates may be used individually or in mixtures of two or more types.

[0028] By using an ultraviolet-curable resin as the binder resin for the above-mentioned easy-adhesion layer, solvents other than hydrocarbon solvents can be used in the coating liquid for forming the easy-adhesion layer (hereinafter also referred to as "paint for the easy-adhesion layer"). Therefore, even when the above-mentioned paint for the easy-adhesion layer is applied to a cycloolefin polymer film substrate that has low solvent resistance to hydrocarbon solvents such as toluene, the occurrence of chemical cracks in the cycloolefin polymer film substrate can be prevented. Furthermore, by using an ultraviolet-curable resin as the binder resin for the above-mentioned easy-adhesion layer, the cured easy-adhesion layer has good solvent resistance to hydrocarbon solvents such as toluene. Therefore, hydrocarbon solvents such as toluene can be used as the solvent in the coating liquid for forming the hard coat layer applied on the easy-adhesion layer (hereinafter also referred to as "paint for the hard coat"), which is advantageous in paint design.

[0029] Furthermore, the UV-curable resin used in the above-mentioned easy-adhesion layer preferably uses a monomer, oligomer, or polymer with a weight-average molecular weight in the range of 500 to 3600, more preferably in the range of 500 to 3000, and even more preferably in the range of 500 to 2400. If the weight-average molecular weight is less than 500, curing shrinkage is large when cured by UV irradiation, causing the hard coat film to curl towards the hard coat layer side, resulting in problems during subsequent processing steps and poor processability. Also, if the weight-average molecular weight exceeds 3600, it is unsuitable because the hardness of the easy-adhesion layer is insufficient and it becomes difficult to obtain solvent resistance to hydrocarbon solvents in the easy-adhesion layer.

[0030] Furthermore, in addition to the UV-curing resin described above, thermoplastic resins such as polyethylene, polypropylene, polystyrene, polycarbonate, polyester, acrylic, styrene-acrylic, and cellulose, as well as thermosetting resins such as phenolic resin, urea resin, unsaturated polyester, epoxy, and silicon resin, may be included in the easy-adhesion layer, within limits that do not impair the effects of the present invention.

[0031] In the present invention, the easy-adhesion layer contains inorganic fine particles. By including inorganic fine particles in the easy-adhesion layer, the adhesion (initial adhesion and lightfastness) between the cycloolefin polymer film substrate and the easy-adhesion layer can be improved, and the adhesion (initial adhesion and lightfastness) between the easy-adhesion layer and the hard coat layer can also be improved. By including inorganic fine particles in the easy-adhesion layer, surface irregularities are formed on the easy-adhesion layer, increasing the contact interface with the substrate film and the hard coat layer (increasing the surface area of ​​the easy-adhesion layer). Furthermore, the hard coat layer penetrates and solidifies within the surface irregularities of the easy-adhesion layer, acting like a wedge (anchoring force), thereby improving adhesion. In other words, the surface irregularities of the outermost layer of the easy-adhesion layer can be adjusted to an optimal range for adhesion with the substrate film and the hard coat layer.

[0032] Examples of inorganic fine particles include silica, alumina, zinc oxide, titanium oxide, and cerium oxide. Regarding particle size, for example, the use of fine particles with an average particle size of 5 nm to 300 nm is preferable. If the average particle size is less than 5 nm, the aforementioned improvement in adhesion cannot be sufficiently obtained. On the other hand, if the average particle size exceeds 300 nm, the transparency of the easily adhesive layer may decrease.

[0033] In the present invention, the amount of inorganic fine particles blended is preferably 5 to 40 parts by mass per 100 parts by mass of the UV-curable resin of the easy-adhesion layer. If the amount of inorganic fine particles blended is less than 5 parts by mass, the above-mentioned effect of improving adhesion cannot be sufficiently obtained. On the other hand, if the amount blended exceeds 40 parts by mass, the transparency of the easy-adhesion layer decreases.

[0034] The coating for forming the above-mentioned easy-adhesion layer contains a photopolymerization initiator. As such a photopolymerization initiator, commercially available acetophenones such as IRGACURE 651 and IRGACURE 184 (both brand names: manufactured by BASF), or benzophenones such as IRGACURE 500 (brand name: manufactured by BASF) can be used.

[0035] Furthermore, leveling agents can be added to the above-mentioned easy-adhesion layer to adjust surface properties (such as surface free energy and water contact angle) and improve coating properties. Known leveling agents such as fluorine-based, acrylic-based, siloxane-based, and their adducts or mixtures can be used. The amount added can be appropriately determined, for example, depending on the adjustment of surface properties and coating properties.

[0036] Furthermore, other additives such as defoaming agents, antifouling agents, antioxidants, antistatic agents, and light stabilizers may be added to the above-mentioned easy-adhesion layer as needed, provided that they do not impair the effects of the present invention.

[0037] In the present invention, the thickness (coating film thickness) of the easy-adhesion layer is preferably in the range of 0.1 μm to 2.0 μm. If the thickness of the easy-adhesion layer is less than 0.1 μm, the above-mentioned improvement in adhesion cannot be sufficiently obtained, and it becomes difficult to obtain solvent resistance of the easy-adhesion layer to hydrocarbon solvents. On the other hand, from the viewpoint of thinning the hard coat film, it is desirable that the thickness of the easy-adhesion layer be 2.0 μm or less.

[0038] The above-mentioned easy-adhesion layer is formed by dissolving and dispersing the above-mentioned inorganic fine particles, photopolymerization initiator, and optionally leveling agent and other additives in a suitable solvent, in addition to the ionizing radiation-curable resin, and then coating the cycloolefin polymer film (base film) with the coating, drying it, and curing it by irradiating it with UV light. In this case, the solvent can be appropriately selected according to the solubility of the resin contained therein, and it is preferable to use an organic solvent with a boiling point of 50°C to 120°C, for example, from the viewpoint of workability during coating and drying properties. As such organic solvents, for example, ester solvents such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and methyl lactate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and alcohol solvents such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, and butanol-based solvents can be used individually or in combination of several types as appropriate. As mentioned above, by using an ultraviolet-curable resin as the binder resin for the easy-adhesion layer, solvents other than hydrocarbon solvents can be used as the solvent for the easy-adhesion layer coating. This makes it possible to prevent the occurrence of chemical cracks in the cycloolefin polymer film substrate even when the coating for the easy-adhesion layer is applied to a cycloolefin polymer film substrate that has low solvent resistance to hydrocarbon solvents such as toluene.

[0039] The above-mentioned easy-adhesion layer coating can be applied to a substrate film using known coating methods such as gravure coating, microgravure coating, fountain bar coating, slide die coating, slot die coating, screen printing, and spray coating. The coating applied to the cycloolefin polymer film is dried at a temperature of approximately 50 to 120°C, while appropriately adjusting the drying conditions (temperature in the drying oven, air velocity in the oven, drying time, etc.) to remove the solvent and form a coating film.

[0040] Furthermore, the amount of ultraviolet (UV) irradiation after the formation of the easy-adhesion layer coating should be the amount necessary to give the easy-adhesion layer appropriate hardness, and can be set appropriately depending on the type of UV-curable resin, etc.

[0041] For example, the amount of ultraviolet radiation is 50-300 mJ / cm². 2 The following setting is preferable: Integrated light intensity of 50 mJ / cm². 2 If the value is less than 300 mJ / cm², sufficient adhesion between the cycloolefin polymer film substrate and the easy-adhesion layer cannot be obtained. On the other hand, if the cumulative light intensity is 300 mJ / cm², sufficient adhesion between the cycloolefin polymer film substrate and the easy-adhesion layer cannot be obtained. 2 If the pressure exceeds this limit, deformation may occur in the cycloolefin polymer film substrate, potentially impairing its appearance.

[0042] Furthermore, in the present invention, it is preferable that the surface free energy on the surface of the easy-adhesion layer is 22 mN / m or more. Here, the surface free energy mentioned above is defined as "the free energy possessed by a unit area of ​​the surface," and refers to the excess energy possessed by the surface of the easily adhering layer compared to the interior of the layer (bulk). The greater the surface free energy of a solid, the easier it is for gases and fine particles to be adsorbed, the easier it is for liquids to wet, and the easier it is for them to adhere to other solids.

[0043] This surface free energy can be measured by analyzing the contact angle between water and hexadecane using a contact angle meter or similar device, employing the Kaelble-Uy method. Specifically, the surface free energy of the easy-adhesion layer described above was calculated using the Kaelble-Uy method by dropping 1 μL of water (pure water) onto the surface of the easy-adhesion layer with a DM-701 fully automatic contact angle meter manufactured by Kyowa Interface Science Co., Ltd., measuring the contact angle after 30 seconds, then dropping 1 μL of n-hexadecane onto the surface of the easy-adhesion layer and measuring the contact angle after 30 seconds, and using the obtained contact angles of water and n-hexadecane.

[0044] The surface free energy value of the easy-adhesion layer indicates an indicator of its adhesion to the resin of the hard coat layer. In this invention, a surface free energy of 22 mN / m or higher increases the intermolecular force between the molecules of the hard coat layer resin and the molecules of the easy-adhesion layer, thereby contributing to improved adhesion to the hard coat layer. If this surface free energy is less than 22 mN / m, problems such as deterioration of adhesion to the hard coat layer may occur, or repellency defects may occur during the coating of the hard coat layer. In the present invention, the surface free energy of the easily adhering layer is particularly preferably 25 mN / m or more. Furthermore, if the surface free energy of the above-mentioned easy-adhesion layer is too high, it can lead to problems such as dirt easily adhering to the surface, resulting in foreign matter contamination, and reduced scratch resistance. Therefore, the upper limit of the surface free energy is preferably 40 mN / m or less, more preferably 38 mN / m or less, and even more preferably 35 mN / m or less.

[0045] Furthermore, the surface free energy of the easy-to-adhere layer can be adjusted, for example, by adding a leveling agent to the easy-to-adhere layer (such as the type and amount of the leveling agent).

[0046] Furthermore, in the present invention, it is preferable that the water contact angle on the surface of the easy-adhesion layer is 90 degrees or less. The water contact angle on the surface of the easy-adhesion layer described above is obtained by using a fully automatic contact angle meter DM-701 manufactured by Kyowa Interface Science Co., Ltd., by dropping 1 μL of water (pure water) onto the surface of the easy-adhesion layer and measuring the contact angle after 30 seconds.

[0047] The water contact angle on the surface of the easy-adhesion layer is one indicator of its adhesion to the resin used in the hard coat layer. In this invention, when the water contact angle on the surface of the easy-adhesion layer is 90 degrees or less, the intermolecular forces between the molecules of the hard coat layer resin and the molecules of the easy-adhesion layer become larger, which contributes to improved adhesion to the hard coat layer. On the other hand, if this contact angle is greater than 90 degrees, problems such as deterioration of adhesion to the hard coat layer may occur, or repellency defects may occur during the coating of the hard coat layer. In the present invention, it is particularly preferable that the water contact angle on the surface of the easily adhesive layer is 85 degrees or less. Furthermore, if this water contact angle is too low, the scratch resistance of the easily bonded layer tends to be poor, so it is desirable that it be 50 degrees or higher.

[0048] Furthermore, the water contact angle on the surface of the easy-adhesion layer can be adjusted, for example, by adding a leveling agent to the easy-adhesion layer (such as the type and amount of the leveling agent).

[0049] [Hard coat layer] Next, the hard coat layer of the hard coat film described above will be explained. In the present invention, the hard coat layer contains at least an ultraviolet-curable resin, an ultraviolet absorber, and a dye. In the present invention, it is preferable to use an ultraviolet-curable resin as the resin included in the hard coat layer, in particular, because it imparts surface hardness (pencil hardness, scratch resistance) to the hard coat layer, and the degree of crosslinking can be adjusted by the amount of ultraviolet exposure, thereby enabling adjustment of the surface hardness of the hard coat layer.

[0050] The UV-curable resin used in the present invention is not particularly limited as long as it is a transparent resin that hardens when irradiated with ultraviolet (UV) light. However, it is preferable that it is composed of a UV-curable polyfunctional acrylate having three or more (meth)acryloyloxy groups in one molecule in order to achieve coating hardness and for the hard coat layer to form a three-dimensional cross-linked structure. Specific examples of UV-curable polyfunctional acrylates having three or more (meth)acryloyloxy groups in one molecule include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane ethoxytriacrylate, glycerin propoxytriacrylate, and ditrimethylolpropane tetraacrylate. Furthermore, polyfunctional acrylates may be used not only individually, but also in mixtures of two or more types.

[0051] Furthermore, the UV-curable resin used in the hard coat layer preferably has a weight-average molecular weight in the range of 500 to 3600, more preferably in the range of 500 to 3000, and even more preferably in the range of 500 to 2400. If the weight-average molecular weight is less than 500, curing shrinkage is large when cured by UV irradiation, causing the hard coat film to curl towards the hard coat layer side, resulting in problems in subsequent processing steps and poor processability. Also, if the weight-average molecular weight exceeds 3600, the flexibility of the hard coat layer increases, but the hardness is insufficient, making it unsuitable.

[0052] Furthermore, when the UV-curable resin used in the hard coat layer has a weight-average molecular weight of less than 1500, it is desirable that the number of functional groups per molecule be between 3 and 10. When the weight-average molecular weight of the UV-curable resin is 1500 or more, it is desirable that the number of functional groups per molecule be between 3 and 20. Within these ranges, curling can be suppressed, and appropriate processability can be maintained.

[0053] Furthermore, in addition to the UV-curing resins mentioned above, thermoplastic resins such as polyethylene, polypropylene, polystyrene, polycarbonate, polyester, acrylic, styrene-acrylic, and cellulose, as well as thermosetting resins such as phenolic resins, urea resins, unsaturated polyesters, epoxy, and silicon resins, may be included in the hard coat layer, provided that they do not impair the hardness and scratch resistance of the hard coat layer.

[0054] In the present invention, the hard coat layer contains, in addition to the UV-curable resin, a UV absorber and a dye.

[0055] In the present invention, ultraviolet absorbers with a maximum absorption wavelength (λmax) in the range of 350 nm to 380 nm are particularly preferred. In the present invention, it is preferable to use, for example, benzotriazole-based ultraviolet absorbers, hydroxyphenyltriazine-based ultraviolet absorbers, and it is particularly preferable to use these benzotriazole-based ultraviolet absorbers and hydroxyphenyltriazine-based ultraviolet absorbers in combination.

[0056] Furthermore, dyes used in the present invention are particularly preferred if their maximum absorption wavelength (λmax) is in the range of 395 nm to 415 nm. In the present invention, for example, it is preferable that the above-mentioned dye is a cyanine dye.

[0057] The hard coat film of the present invention, by containing the above-mentioned ultraviolet absorber and dye in the hard coat layer, can satisfy the scope of the present invention in terms of spectral characteristics (rate of light reduction at each wavelength from 350 nm to 450 nm, and rate of change in light transmittance after lightfastness testing). In the present invention, the amount of the UV absorber is preferably 1 to 30 parts by mass per 100 parts by mass of the UV-curable resin in the hard coat layer. If the amount of UV absorber is less than 1 part by mass, the spectral characteristics of the present invention cannot be sufficiently satisfied. On the other hand, if the amount exceeds 30 parts by mass, it becomes difficult for the b* value, which is an indicator of yellowness, to satisfy the range of the present invention, and the hardness and adhesion of the hard coat layer are insufficient, making it unsuitable. Furthermore, the amount of the above-mentioned dye is preferably 0.1 to 10 parts by mass per 100 parts by mass of the UV-curable resin in the hard coat layer. If the amount of UV absorber is less than 0.1 parts by mass, the spectral characteristics of the present invention cannot be fully satisfied. On the other hand, if the amount exceeds 10 parts by mass, it becomes difficult for the b* value, which is an indicator of yellowness, to satisfy the range of the present invention, and the hardness and adhesion of the hard coat layer are insufficient, making it unsuitable.

[0058] Furthermore, it is possible to further improve surface hardness (scratch resistance) by incorporating inorganic oxide fine particles into the hard coat layer. In this case, the average particle size of the inorganic oxide fine particles is preferably in the range of 5 to 50 nm, and more preferably in the range of 10 to 40 nm. If the average particle size is less than 5 nm, it is difficult to obtain sufficient surface hardness. On the other hand, if the average particle size exceeds 50 nm, the gloss and transparency of the hard coat layer tend to decrease, and the flexibility may also decrease.

[0059] In the present invention, examples of the inorganic oxide fine particles include alumina and silica. Among these, alumina, which has aluminum as its main component, is particularly preferred because it has high hardness and therefore can achieve the desired effect with a smaller amount of additive than silica.

[0060] In the present invention, the content of inorganic oxide fine particles is preferably 0.1 to 10.0 parts by mass per 100 parts by mass of UV-curable resin in the hard coat layer. If the content of inorganic oxide fine particles is less than 0.1 parts by mass, it is difficult to obtain an improvement in surface hardness (scratch resistance). On the other hand, if the content exceeds 10.0 parts by mass, it is undesirable because it increases haze.

[0061] The hard coat coating used to form the hard coat layer described above may contain a photopolymerization initiator. Suitable photopolymerization initiators include commercially available acetophenones such as IRGACURE 651 and IRGACURE 184 (both brand names: BASF), and benzophenones such as IRGACURE 500 (brand name: BASF).

[0062] Leveling agents can be used in the hard coat layer described above to improve coating properties. Known leveling agents such as fluorine-based, acrylic-based, siloxane-based, and their adducts or mixtures can be used. The amount added can be in the range of 0.03 to 3.0 parts by mass per 100 parts by mass of the solid content of the resin in the hard coat layer. Furthermore, in applications such as touch panels, where adhesion to cover glass (CG), transparent conductive material (TSP), liquid crystal module (LCM), etc. of touch panel terminals is required using optically transparent adhesive (OCR), it is preferable to use acrylic-based or fluorine-based leveling agents with high surface free energy (approximately 30 mN / m or more).

[0063] Other additives to be added to the hard coat layer may include, as necessary, defoaming agents, surface tension modifiers, antifouling agents, antioxidants, antistatic agents, light stabilizers, etc., to the extent that they do not impair the effects of the present invention.

[0064] The hard coat layer described above is formed by coating the easy-adhesion layer with a hard coat coating prepared by dissolving and dispersing the UV absorber, dye, photopolymerization initiator, and other additives described above in a suitable solvent, in addition to the UV-curable resin described above. After drying, the coating is cured by irradiation with UV light. The solvent can be appropriately selected according to the solubility of the resin being blended, and should be a solvent that can uniformly dissolve or disperse at least the solid components (resin, UV absorber, dye, photopolymerization initiator, and other additives). Such solvents may include, for example, aromatic solvents such as toluene, xylene, and n-heptane; aliphatic solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane; ester solvents such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and methyl lactate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and alcohol solvents such as methanol, ethanol, isopropyl alcohol, and n-propyl alcohol. Known organic solvents can be used individually or in combination of several types as appropriate. According to the present invention, since the easy-adhesion layer has good solvent resistance to hydrocarbon solvents, a good coating appearance can be obtained even when a hard coat paint containing a hydrocarbon solvent such as toluene is directly applied to the easy-adhesion layer.

[0065] There are no particular limitations on the application method for the hard coat coating that forms the hard coat layer described above. However, it is usually applied using known coating methods such as gravure coating, microgravure coating, fountain bar coating, slide die coating, slot die coating, screen printing, or spray coating, and then dried at a temperature of approximately 50 to 120°C.

[0066] The amount of ultraviolet (UV) radiation applied after the formation of the hard coat layer should be sufficient to give the hard coat layer adequate hardness, and can be set appropriately depending on the type of UV-curable resin, etc.

[0067] In this invention, the thickness of the hard coat layer (coating thickness) is preferably in the range of 1.0 μm to 10.0 μm, and more preferably in the range of 1.5 μm to 5.0 μm. A coating thickness of less than 1.0 μm is undesirable because it reduces the required hardness (e.g., scratch resistance). Furthermore, a coating thickness exceeding 10.0 μm is undesirable because it is prone to strong curling, reducing handling in the manufacturing process, and also from the viewpoint of thinning the hard coat film.

[0068] As described above, the hard coat film of the present invention is formed by laminating a hard coat layer containing an ultraviolet-curable resin, an ultraviolet absorber, and a dye on at least one side of a cycloolefin polymer film with a thickness of 50 μm or less, via an easy-adhesion layer made of an ultraviolet-curable resin containing inorganic fine particles.

[0069] The hard coat film of the present invention is further characterized in that it satisfies the following condition (A), and the light reduction rate (%) at each wavelength satisfies the following conditions (B) to (L). (A) The b* value is 7.0 or less. (B) The light reduction rate at a wavelength of 350 nm is 95.0% or higher. (C) The light reduction rate at a wavelength of 360 nm is 95.0% or higher. (D) The light reduction rate at a wavelength of 370 nm is 95.0% or higher. (E) The light reduction rate at a wavelength of 380 nm is 95.0% or higher. (F) The light reduction rate at a wavelength of 390 nm is 95.0% or higher. (G) The light reduction rate at a wavelength of 400 nm is 95.0% or higher. (H) The light reduction rate at a wavelength of 410 nm is 95.0% or higher. (I) The light reduction rate at a wavelength of 420 nm is 75.0% or less. (J) The light reduction rate at a wavelength of 430 nm is 30.0% or less. (K) The light attenuation rate at a wavelength of 440 nm is 7.0% or less. (L) The light reduction rate at a wavelength of 450 nm is 2.0% or less.

[0070] Here, the light attenuation rate at each wavelength is calculated using the following equation 1. Equation 1) Light reduction rate (%) at each wavelength = (Transmittance of the cycloolefin polymer film alone at that wavelength - Transmittance of the hard coat film at that wavelength) / Transmittance of the cycloolefin polymer film alone at that wavelength

[0071] Furthermore, the b* value specified in the above condition (A) is an indicator of noble color, and a larger value indicates a stronger noble color. The specific methods for measuring the b* value and light transmittance at each wavelength will be explained in the examples described below.

[0072] The hard coat film of the present invention is provided with a hard coat layer made of an ultraviolet-curable resin containing the aforementioned ultraviolet absorber and dye, and is a hard coat film that satisfies the optical properties of the present invention, i.e., the above conditions (A) to (L). As a result, the hard coat film of the present invention suppresses the b* value, which is an indicator of yellowness, and does not adversely affect the display color of the organic EL display, while suppressing damage such as degradation of some polymers and fading or discoloration of dyes by having a light reduction rate of 95% or more at wavelengths of 350nm to 400nm. Furthermore, in order to improve the durability (light resistance) of light-emitting elements in recent organic EL displays, it is required to sufficiently reduce the light transmittance at 390nm to 410nm in order to protect the light-emitting elements. The hard coat film of the present invention can improve the durability (light resistance) of light-emitting elements in recent organic EL displays by having a light reduction rate of 95% or more at wavelengths of 390nm to 410nm. On the other hand, in the visible light region, wavelengths of 420nm to 450nm require minimizing the light falloff rate in order to ensure the brightness of the display on an organic EL display. The hard coat film of the present invention is able to suppress the light falloff rate in the 420nm to 450nm wavelength range, and does not adversely affect the brightness of the display on an organic EL display.

[0073] Furthermore, the hard coat film of the present invention is subjected to an irradiance of 500 W / m² under conditions of 63°C and 50% relative humidity. 2 The invention is characterized in that, after 100 hours of exposure to ultraviolet light (lightfastness test), the absolute value of the rate of change (Δ%) of light transmittance at each wavelength satisfies the following conditions (M) to (W). (M) The absolute value of the rate of change of light transmittance at a wavelength of 350 nm is 1.0% or less. (N) The absolute value of the rate of change of light transmittance at a wavelength of 360 nm is 1.0% or less. (O) The absolute value of the rate of change of light transmittance at a wavelength of 370 nm is 1.0% or less. (P) The absolute value of the rate of change of light transmittance at a wavelength of 380 nm is 1.0% or less. (Q) The absolute value of the rate of change of light transmittance at a wavelength of 390 nm is 5.0% or less. (R) The absolute value of the rate of change of light transmittance at a wavelength of 400 nm is 10.0% or less. (S) The absolute value of the rate of change of light transmittance at a wavelength of 410 nm is 30.0% or less. (T) The absolute value of the rate of change of light transmittance at a wavelength of 420 nm is 30.0% or less. (U) The absolute value of the rate of change of light transmittance at a wavelength of 430 nm is 10.0% or less. (V) The absolute value of the rate of change of light transmittance at a wavelength of 440 nm is 5.0% or less. (W) The absolute value of the rate of change in light transmittance at a wavelength of 450 nm is 5.0% or less.

[0074] Here, the rate of change (Δ%) of light transmittance at each wavelength is calculated using the following equation 2. Equation 2) Percentage change in light transmittance at each wavelength (Δ%) = Transmittance at that wavelength after the lightfastness test of the hard coat film - Transmittance at that wavelength before the lightfastness test of the hard coat film

[0075] The hard coat film of the present invention is provided with a hard coat layer made of an ultraviolet-curable resin containing the aforementioned ultraviolet absorber and dye, and is a hard coat film that satisfies the optical properties of the present invention, i.e., the above conditions (M) to (W), even after a light resistance test.

[0076] The transmittance at each of the above wavelengths must be maintained even after lightfastness testing, for the purpose of which the hard coat film of the present invention must maintain its performance at wavelengths of 350nm to 400nm, which cause damage such as degradation of some polymers and fading or discoloration of dyes, and wavelengths of 390nm to 410nm, which contribute to protecting the light-emitting elements of recent organic EL displays. The hard coat film of the present invention can suppress the rate of change in light transmittance at wavelengths of 350nm to 400nm and 390nm to 410nm, thereby suppressing the degradation of the display of organic EL displays. Furthermore, it is also necessary to maintain the performance at wavelengths of 420nm to 450nm in the visible light region even after lightfastness testing, and the hard coat film of the present invention can suppress the rate of change in light transmittance, thereby maintaining the brightness of the display of organic EL displays.

[0077] Furthermore, the hard coat film of the present invention can satisfy the following conditions (X) to (AA). (X) The thickness of the easy-adhesion layer is in the range of 0.1 to 2.0 μm. (Y) The thickness of the hard coat layer is in the range of 1.0 to 10.0 μm. (Z) The remaining percentages of the hard coat layer and the easy-adhesion layer of the hard coat film, as measured by the cross-cut method of JIS-K5600-5-6, are both 100%. (AA) The hard coat film is subjected to an irradiance of 500 W / m² under conditions of 63°C and 50% relative humidity. 2 Furthermore, after 100 hours of exposure to ultraviolet light (lightfastness test), the remaining percentages of both the hard coat layer and the easy-adhesion layer, as measured by the cross-cut method of JIS-K5600-5-6, are 100%.

[0078] The above conditions (X) and (Y) are as described above. Furthermore, the hard coat film of the present invention satisfies the above conditions (Z) and (AA). As a result, even when using a cycloolefin polymer film as a substrate, it is possible to obtain a hard coat film with excellent adhesion (initial adhesion and lightfastness) between the easy-adhesion layer and the hard coat layer provided on the substrate film, even on substrates with few polar groups and poor adhesion. Further details of the adhesion test by the cross-cut method of JIS-K5600-5-6 and the lightfastness test described above will be explained in the examples below.

[0079] As described in detail above, according to the present invention, a hard coat film can be obtained that uses a cycloolefin polymer film as a substrate and exhibits excellent adhesion (initial adhesion and lightfastness) between the easy-adhesion layer and the hard coat layer provided on the substrate film, even on substrates with few polar groups and poor adhesion. Furthermore, according to the present invention, the easy-adhesion layer provided on the substrate film has good solvent resistance to hydrocarbon solvents, and a hard coat film can be provided that can obtain a good coating appearance even when a hard coat paint containing a hydrocarbon solvent is directly applied to the easy-adhesion layer. Moreover, according to the present invention, when used as a protective film for the surface of an organic EL display, a hard coat film can be provided that does not adversely affect the color and brightness of the display of the organic EL display, improves the durability (lightfastness) of the light-emitting element of the organic EL display, and suppresses the deterioration of the display of the organic EL display. In particular, the hard coat film of the present invention is suitable when a thin film of cycloolefin polymer is used as a substrate. [Examples]

[0080] Next, embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following embodiments. In the following descriptions, "parts" refers to parts by mass unless otherwise specified, and "%" refers to percentage by mass unless otherwise specified.

[0081] (Example 1) [Preparation of coating liquid for easy adhesion layer formation] 100 parts of an acrylate-based UV-curing resin coating (Luxidia CH-C-1623 (trade name); manufactured by DIC Corporation) containing the silica fine particles (average particle size 100 nm) of the present invention were diluted with methyl ethyl ketone / 1-methoxy-2-propanol = 50 / 50 (parts by weight) to prepare a coating liquid for forming an easily adhesive layer (hereinafter referred to as "easily adhesive layer coating") with a solid content concentration of 10%.

[0082] [Preparation of coating liquid for hard coat layer formation] The main component is 85 parts of an acrylate-based UV-curable resin coating containing the benzotriazole-based UV absorber of the present invention (HFC-UVA-1 (trade name); manufactured by Harima Chemicals, Inc.; maximum absorption wavelength of the benzotriazole-based UV absorber: 370 nm), 3.5 parts of Irgacure 184 (photopolymerization initiator, manufactured by BASF), 0.5 parts of a surface modifier (Futergent 681; manufactured by Neos Co., Ltd.), and the hydroxyphenyltriazine-based UV absorber of the present invention (Tinuvin 4 Ten parts of 77 (product name); manufactured by BASF Japan Ltd.; maximum absorption wavelength: 356 nm) and 1.0 part of the cyanine dye of the present invention (NK-9994 (product name); manufactured by Hayashibara Co., Ltd.; maximum absorption wavelength: 405 nm) were mixed and diluted with toluene / methyl ethyl ketone / propylene glycol monomethyl ether acetate = 15 / 35 / 50 (parts by weight) to prepare a hard coat layer forming coating liquid (hereinafter referred to as "hard coat paint") with a final solids content of 30%.

[0083] [Production of hard coat film] A cycloolefin polymer film, Zeonor Film ZD12 (manufactured by Nippon Zeon Co., Ltd.), with a thickness of 26 μm, was coated with the above-mentioned easy-adhesion layer coating using a bar coater. It was then dried and solidified in a 60°C drying oven for 1 minute using hot air, forming an easy-adhesion layer coating with a thickness of 0.2 μm. This was then subjected to UV irradiation at a UV irradiation dose of 50 mJ / cm² using a UV irradiation device set 60 mm above the coated surface. 2 The film was cured by ultraviolet irradiation to form an easily adhesive layer, and an easily adhesive layer coated film was obtained. Next, the hard coat paint described above was applied to the easy-adhesion layer of the easy-adhesion coated film using a bar coater, and then dried with hot air in an 80°C drying oven for 1 minute to form a coating layer with a thickness of 4.5 μm. This was then subjected to UV irradiation at a UV irradiation dose of 100 mJ / cm using a UV irradiation device set at a height of 60 mm above the coated surface. 2 The hard coat film of this Example 1 was prepared by curing it with ultraviolet irradiation.

[0084] (Example 2) The hard coat film of Example 2 was prepared in the same manner as in Example 1, except that the cycloolefin polymer film of Example 1 was replaced with a 50 μm thick Zeonor film ZF16 (manufactured by Nippon Zeon Co., Ltd.).

[0085] (Example 3) The hard coat film of Example 3 was prepared in the same manner as in Example 1, except that the cycloolefin polymer film of Example 1 was replaced with a 13 μm thick Zeonor film ZF12 (manufactured by Nippon Zeon Co., Ltd.).

[0086] (Example 4) [Preparation of coatings for easy-adhesion layers] 100 parts of an acrylate-based UV-curing resin coating (Beamset NOP-102 (product name); manufactured by Arakawa Chemical Industries, Ltd.) containing the silica fine particles (average particle size 100 nm) of the present invention were diluted with 1-methoxy-2-propanol to prepare an easy-adhesion layer coating with a solid content concentration of 10%.

[0087] [Production of hard coat film] The hard coat film of Example 4 was prepared in the same manner as in Example 1, except that a coating for an easily adhering layer having the above composition was used.

[0088] (Example 5) [Preparation of hard coat paints] A hard coat coating with a final solids content of 30% was prepared by mixing 75 parts of acrylate-based UV-curing resin (NK Ester A-9550 (trade name); manufactured by Shin Nakamura Chemical Industry Co., Ltd.) as the main component, 10 parts of the benzotriazole-based UV absorber of the present invention (Tinuvin 970 (trade name); manufactured by BASF Japan Ltd.; maximum absorption wavelength: 378 nm), 3.5 parts of Irgacure 184 (photopolymerization initiator, manufactured by BASF), 0.5 parts of surface modifier (Futergent 681; manufactured by Neos Co., Ltd.), 10 parts of the hydroxyphenyltriazine-based UV absorber of the present invention (Tinuvin 477 (trade name); manufactured by BASF Japan Ltd.), and 1.0 part of the cyanine dye of the present invention (NK-9994 (trade name); manufactured by Hayashibara Co., Ltd.) with toluene / methyl ethyl ketone / propylene glycol monomethyl ether acetate = 15 / 35 / 50 (parts by weight).

[0089] [Production of hard coat film] A hard coat film of Example 5 was prepared in the same manner as in Example 1, except that a hard coat coating having the above composition was used.

[0090] (Example 6) [Preparation of hard coat paints] A hard coat coating with a final solids content of 30% was prepared by mixing 74 parts of acrylate-based UV-curing resin (NK Ester A-9550 (trade name); manufactured by Shin Nakamura Chemical Industry Co., Ltd.) as the main component, 10 parts of the benzotriazole-based UV absorber of the present invention (ADEKA Stab LA-29 (trade name); manufactured by ADEKA Corporation; maximum absorption wavelength: 350 nm), 3.5 parts of Irgacure 184 (photopolymerization initiator; manufactured by BASF), 0.5 parts of surface modifier (Futergent 681; manufactured by Neos Co., Ltd.), 10 parts of the hydroxyphenyltriazine-based UV absorber of the present invention (Tinuvin 477 (trade name); manufactured by BASF Japan Ltd.), and 2.0 parts of the cyanine dye of the present invention (NK-9994 (trade name); manufactured by Hayashibara Co., Ltd.) with toluene / methyl ethyl ketone / propylene glycol monomethyl ether acetate = 15 / 35 / 50 (parts by weight).

[0091] [Production of hard coat film] A hard coat film of Example 6 was prepared in the same manner as in Example 1, except that a hard coat coating having the above composition was used.

[0092] (Example 7) The hard coat film of Example 7 was prepared in the same manner as in Example 1, except that the cyanine dye of the present invention (NK-9994 (trade name); manufactured by Hayashibara Corporation) in the hard coat coating of Example 1 was changed to the cyanine dye of the present invention (NK-10490 (trade name); manufactured by Hayashibara Corporation; maximum absorption wavelength; 405 nm), and the cycloolefin film was changed to Zeonor film ZD12 (manufactured by Nippon Zeon Co., Ltd.) with a thickness of 22 μm.

[0093] (Example 8) The hard coat film of Example 8 was prepared in the same manner as in Example 1, except that the thickness of the easy-adhesion layer in Example 1 was changed to 1.8 μm.

[0094] (Example 9) The hard coat film of Example 9 was prepared in the same manner as in Example 1, except that the thickness of the hard coat layer was changed to 8.0 μm.

[0095] (Comparative Example 1) [Preparation of hard coat paints] A hard coat coating with a final solids content of 30% was prepared by mixing 96 parts of acrylate-based UV-curing resin (NK Ester A-9550 (product name); manufactured by Shin Nakamura Chemical Industry Co., Ltd.) as the main component, adding 3.5 parts of Irgacure 184 (photopolymerization initiator, manufactured by BASF) and 0.5 parts of surface modifier (Futergent 681; manufactured by Neos Co., Ltd.), and diluting with toluene / methyl ethyl ketone / propylene glycol monomethyl ether acetate = 15 / 35 / 50 (parts by weight).

[0096] [Production of hard coat film] A hard coat film of Comparative Example 1 was prepared in the same manner as in Example 1, except that a hard coat coating having the above composition was used.

[0097] (Comparative Example 2) [Preparation of hard coat paints] A hard coat coating with a final solids content of 30% was prepared by mixing 75 parts of acrylate-based UV-curing resin (NK Ester A-9550 (product name); manufactured by Shin Nakamura Chemical Industry Co., Ltd.) as the main component, 10 parts of dihydroxybenzophenone-based UV absorber (Uvinul 3050 (product name); manufactured by BASF Japan Ltd.; maximum absorption wavelength: 345 nm), 3.5 parts of Irgacure 184 (photopolymerization initiator, manufactured by BASF), 0.5 parts of surface modifier (Futergent 681; manufactured by Neos Co., Ltd.), 10 parts of hydroxyphenyltriazine-based UV absorber (Tinuvin 477 (product name); manufactured by BASF Japan Ltd.), and 1.0 part of cyanine dye (NK-9994 (product name); manufactured by Hayashibara Co., Ltd.) with toluene / methyl ethyl ketone / propylene glycol monomethyl ether acetate = 15 / 35 / 50 (parts by weight).

[0098] [Production of hard coat film] A hard coat film for Comparative Example 2 was prepared in the same manner as in Example 1, except that a hard coat coating having the above composition was used, and the cycloolefin film in Example 1 was replaced with a 50 μm thick Zeonor film ZF16 (manufactured by Nippon Zeon Co., Ltd.).

[0099] (Comparative Example 3) [Preparation of hard coat paints] A hard coat coating with a final solids content of 30% was prepared by mixing 80 parts of an acrylate-based UV-curing resin coating containing a benzotriazole-based UV absorber (HFC-UVA-1 (trade name); manufactured by Harima Chemicals, Inc.; maximum absorption wavelength of the benzotriazole-based UV absorber: 370 nm) as the main component, 3.5 parts of Irgacure 184 (photopolymerization initiator, manufactured by BASF), 0.5 parts of a surface modifier (Futergent 681; manufactured by Neos Co., Ltd.), 10 parts of a hydroxyphenyltriazine-based UV absorber (Tinuvin 477 (trade name); manufactured by BASF Japan Ltd.; maximum absorption wavelength: 356 nm), and 6 parts of a merocyanine dye (FDB-009 (trade name); manufactured by Yamada Chemical Industries, Ltd.; maximum absorption wavelength: 402 nm) with toluene / methyl ethyl ketone / propylene glycol monomethyl ether acetate = 15 / 35 / 50 (parts by weight).

[0100] [Production of hard coat film] A hard coat film of Comparative Example 3 was prepared in the same manner as in Example 1, except that a hard coat coating having the above composition was used.

[0101] (Comparative Example 4) [Preparation of coatings for easy-adhesion layers] 100 parts of an acrylate-based UV-curing resin coating (Luxidia EPS-1306 (trade name); manufactured by DIC Corporation) that does not contain silica microparticles were diluted with methyl ethyl ketone / 1-methoxy-2-propanol = 50 / 50 (parts by weight) to prepare an easy-adhesion coating with a solid content of 10%.

[0102] [Production of hard coat film] A hard coat film of Comparative Example 4 was prepared in the same manner as in Example 1, except that a coating for an easily adhering layer having the above composition was used.

[0103] (Comparative Example 5) [Preparation of coatings for easy-adhesion layers] A coating for easy adhesion was prepared by diluting 100 parts of a polyolefin resin (Surflen P-1000 (trade name); manufactured by Mitsubishi Chemical Corporation), which is a thermoplastic resin, with butyl acetate to create a coating with a solid content of 10%.

[0104] [Production of hard coat film] A hard coat film of Comparative Example 5 was prepared in the same manner as in Example 1, except that a coating for an easily adhering layer having the above composition was used.

[0105] <Rating> The hard coat films prepared in the examples and comparative examples described above were evaluated for the following items, and the results are summarized in Tables 1, 2, and 3.

[0106] <Thickness of the coating film> The film thickness of the easy-adhesion layer and the hard coat layer was measured using a Thin-Film Analyzer F20 (product name) (manufactured by FILMETRICS).

[0107] <Adhesion (Initial Adhesion)> Adhesion was evaluated by a cross-cut peel test in accordance with the JIS-K5600-5-6 cross-cut method. Specifically, for each hard coat film prepared in the examples and comparative examples, under normal conditions, i.e., constant temperature and humidity conditions (25°C, 50%RH), a cutter knife was used to make 11 vertical and 11 horizontal cuts at 1 mm intervals on the hard coat layer forming surface, creating a grid of 100 squares. Adhesive tape No. 252 manufactured by Sekisui Chemical Co., Ltd. was then applied on top of the grid, pressed uniformly with a spatula, and peeled off in a 180-degree direction. The number of remaining hard coat layers was defined as the remaining percentage (%). The initial adhesion of the easy-adhesion layer was assessed by performing the peel test described above on the film coated with the easy-adhesion layer.

[0108] <Solvent resistance> Solvent resistance was evaluated by dropping toluene onto the surface of the cycloolefin polymer film used in the examples and comparative examples, or each easy-adhesion coated film prepared in the examples and comparative examples, to a diameter of approximately 10 mm. After 3 minutes, the surface was wiped with gauze, and the appearance of the chemical-dropped surface was visually assessed. ○ The evaluated samples were deemed to have good solvent resistance. ○: No change in appearance of the drug application surface. ×: Appearance change under the drug drop

[0109] <b* value> The b* value was measured for each hard coat film prepared in the examples and comparative examples using a spectrophotometer U-3310 manufactured by Hitachi High-Technologies Corporation.

[0110] <Light transmittance at each wavelength> The light transmittance of the hard coat film at each wavelength was measured using a spectrophotometer U-3310 manufactured by Hitachi High-Technologies Corporation. The measurement was carried out at a wavelength range of 250 nm to 800 nm and a scan speed of 600 nm / min. After detecting the light transmittance at each wavelength, the "light reduction rate (%) at each wavelength" shown in the following formula 1 was calculated. When the transmittance of the cycloolefin polymer film alone at the wavelength was 0.0%, the light reduction rate at each wavelength was set to 100%. Formula 1) Light reduction rate (%) at each wavelength = (Transmittance of the cycloolefin polymer film alone at the wavelength - Transmittance of the hard coat film at the wavelength) / (Transmittance of the cycloolefin polymer film alone at the wavelength)

[0111] <Light resistance test> For each hard coat film prepared in the examples and comparative examples, an accelerated light resistance test using an ultraviolet carbon fade meter (performed under the following conditions in accordance with JIS B 7751:2007) was carried out. Light source: Ultraviolet carbon arc lamp Temperature: 63 °C Relative humidity: 50% Irradiance: 500 W / m 2 Irradiation time: 100 hours Period and time of rainfall: No setting

[0112] <Adhesion after light resistance test> The adhesion after the light resistance test was carried out by the same cross-cut test method as the above adhesion, and the remaining number of the hard coat layer was taken as the remaining rate (%). Furthermore, the adhesion of the easy-adhesion layer after the lightfastness test was determined by a peel test of the hard coat film, which had a hard coat layer applied on top of the easy-adhesion layer. For example, if peeling occurred at the easy-adhesion layer, it was determined to be peeling of the easy-adhesion layer.

[0113] <Percentage change in light transmittance at each wavelength> The rate of change in light transmittance at each wavelength of the hard coat film after the lightfastness test was measured using the same spectrophotometer U-3310 under the same conditions as the light transmittance at each wavelength described above. After detecting the light transmittance at each wavelength, the "rate of change in light transmittance at each wavelength (Δ%)" shown in Equation 2 below was calculated. If the rate of change was negative, it was evaluated as an absolute value. Equation 2) Percentage change in light transmittance at each wavelength (Δ%) = Transmittance at that wavelength after the lightfastness test of the hard coat film - Transmittance at that wavelength before the lightfastness test of the hard coat film

[0114] [Table 1]

[0115] [Table 2]

[0116] [Table 3]

[0117] As is clear from the results in Table 1 above, the hard coat films of Examples 1-9 and Comparative Examples 1-3 of the present invention, which used an easy-adhesion layer made of an ultraviolet-curable resin containing silica fine particles, exhibited excellent initial adhesion and lightfast adhesion (adhesion after lightfastness testing). By using an easy-adhesion layer made of an ultraviolet-curable resin containing silica fine particles, it is possible to form a hard coat layer with excellent adhesion (initial adhesion and lightfast adhesion) even on substrate films that have few polar groups and poor adhesion to the hard coat layer, such as cycloolefin polymer films. In other words, according to the present invention, even when using a cycloolefin polymer film as a substrate, it is possible to obtain a hard coat film with excellent adhesion (initial adhesion and lightfast adhesion) between the easy-adhesion layer and the hard coat layer provided on the substrate film, even on substrates with few polar groups and poor adhesion. In Comparative Example 4 in Table 1, the remaining rate of the easy-adhesion layer, the remaining rate after the lightfastness test, the remaining rate of the hard coat layer, and the remaining rate after the lightfastness test are all 0%, which means that delamination occurred at the easy-adhesion layer. When delamination occurs at the easy-adhesion layer, the hard coat layer above it is also peeled off.

[0118] Table 1 above also shows the evaluation results of the solvent resistance of the cycloolefin polymer film and the easy-adhesion layer. The UV absorber and dye used in the hard coat layer made of a UV-curable resin containing the UV absorber and dye of the present invention have hydrocarbon solvents such as toluene as good solvents. Therefore, it is necessary to incorporate hydrocarbon solvents such as toluene into the hard coat coating. However, the cycloolefin polymer film used in the present invention has poor solvent resistance to hydrocarbon solvents such as toluene and dissolves easily. As a result, when the above hard coat coating is applied directly, chemical cracks occur, making it difficult to obtain a good coating appearance. Therefore, the easy-adhesion layer made of a UV-curable resin containing inorganic fine particles (silica fine particles in the example) of the present invention has good solvent resistance to hydrocarbon solvents such as toluene, and even when a hard coat coating containing hydrocarbon solvents such as toluene is applied directly, a good coating appearance can be obtained. However, in the case of Comparative Example 5, which used an easy-adhesion layer made of thermoplastic resin, unlike the easy-adhesion layer made of UV-curable resin containing inorganic fine particles of the present invention, it was not possible to improve solvent resistance to hydrocarbon solvents such as toluene. Therefore, when a hard coat coating paint containing hydrocarbon solvents such as toluene was applied, it was not possible to obtain a good coating appearance, and it was difficult to produce a hard coat film.

[0119] Furthermore, as is clear from the results in Table 2 above, the hard coat film of the present invention is provided with a hard coat layer made of an ultraviolet-curable resin containing the aforementioned ultraviolet absorber and dye, and is a hard coat film that satisfies the predetermined optical properties of the present invention, i.e., the aforementioned conditions (A) to (L). As a result, the hard coat film of the present invention can suppress the b* value, which is an indicator of yellowness, and without adversely affecting the display color of the organic EL display, it is possible to obtain a light reduction rate of 95% or more at wavelengths of 350nm to 400nm that cause damage such as degradation of some polymers and fading or discoloration of dyes, thereby suppressing damage such as degradation of some polymers and fading or discoloration of dyes. Moreover, in order to improve the durability (light resistance) of light-emitting elements in recent organic EL displays, it is required to sufficiently reduce the light transmittance at 390nm to 410nm in order to protect the light-emitting elements. The hard coat film of the present invention can obtain a light reduction rate of 95% or more at wavelengths of 390nm to 410nm, thereby improving the durability (light resistance) of light-emitting elements in recent organic EL displays. On the other hand, in the visible light region, wavelengths of 420nm to 450nm require minimizing the light falloff rate in order to ensure the brightness of the display on an organic EL display. The hard coat film of the present invention is able to suppress the light falloff rate in the 420nm to 450nm wavelength range, and does not adversely affect the brightness of the display on an organic EL display.

[0120] Furthermore, as is clear from the results in Table 3 above, the hard coat film of the present invention is provided with a hard coat layer made of an ultraviolet-curable resin containing the aforementioned ultraviolet absorber and dye, and is a hard coat film that satisfies the optical properties of the present invention, i.e., the aforementioned conditions (M) to (W), even after the light resistance test. The transmittance at each of the above wavelengths must be maintained even after lightfastness testing, for the purpose of which the hard coat film of the present invention must maintain its performance at wavelengths of 350nm to 400nm, which cause damage such as degradation of some polymers and fading or discoloration of dyes, and wavelengths of 390nm to 410nm, which contribute to protecting the light-emitting elements of recent organic EL displays. The hard coat film of the present invention can suppress the rate of change in light transmittance at wavelengths of 350nm to 400nm and 390nm to 410nm, thereby suppressing the degradation of the display of organic EL displays. Furthermore, it is also necessary to maintain the performance at wavelengths of 420nm to 450nm in the visible light region even after lightfastness testing, and the hard coat film of the present invention can suppress the rate of change in light transmittance, thereby maintaining the brightness of the display of organic EL displays.

[0121] In contrast, Comparative Example 1, which uses a hard coat layer made of an ultraviolet-curable resin that does not contain either an ultraviolet absorber or a dye, has the problem of degrading the display of the organic EL display because it is not possible to reduce the transmittance in the 380nm to 410nm range. Furthermore, Comparative Example 2, which uses an ultraviolet absorber of a different type than the ultraviolet absorber preferably used in the present invention, has the problem of insufficient light reduction rate at each wavelength and large change in light transmittance at each wavelength after the lightfastness test, resulting in degrading the display of the organic EL display and failing to achieve improved durability (lightfastness) of the light-emitting element. Moreover, Comparative Example 3, which uses a dye of a different type than the dye preferably used in the present invention, has the problem of insufficient light reduction rate at each wavelength, but high b* value, an indicator of yellowness, which adversely affects the color of the display of the organic EL display, and extremely large change in light transmittance at each wavelength after the lightfastness test, resulting in failing to achieve improved durability (lightfastness) of the light-emitting element of the organic EL display. On the other hand, in Comparative Example 4, which does not use an easy-adhesion layer made of an ultraviolet-curable resin containing inorganic fine particles of the present invention (i.e., an ultraviolet-curable resin that does not contain inorganic fine particles), the adhesion to the substrate film is poor (see Table 1 above), and the hard coat layer made of an ultraviolet-curable resin containing an ultraviolet absorber and a dye is missing, resulting in the problem that protection of the organic EL display cannot be achieved.

Claims

1. A hard coat film is formed in which a hard coat layer containing an ultraviolet-curable resin, an ultraviolet absorber, and a dye is laminated on at least one side of a cycloolefin polymer film with a thickness of 50 μm or less, via an easy-adhesion layer made of an ultraviolet-curable resin containing inorganic fine particles. The aforementioned ultraviolet absorber consists of a combination of a benzotriazole-based ultraviolet absorber and a hydroxyphenyltriazine-based ultraviolet absorber. The UV absorber, comprising the combination of the benzotriazole-based UV absorber and the hydroxyphenyltriazine-based UV absorber, has a maximum absorption wavelength (λmax) in the range of 350 nm to 380 nm, and the maximum absorption wavelength (λmax) of the dye is in the range of 395 nm to 415 nm. A hard coat film characterized in that it satisfies the following condition (A), and the light reduction rate (%) at each wavelength calculated by the following formula 1 satisfies the following conditions (B) to (L). (A) The b* value is 7.0 or less. Equation 1) Light reduction rate (%) at each wavelength = (Transmittance of the cycloolefin polymer film alone at that wavelength - Transmittance of the hard coat film at that wavelength) / Transmittance of the cycloolefin polymer film alone at that wavelength (B) The light reduction rate at a wavelength of 350 nm is 95.0% or higher. (C) The light reduction rate at a wavelength of 360 nm is 95.0% or higher. (D) The light reduction rate at a wavelength of 370 nm is 95.0% or higher. (E) The light reduction rate at a wavelength of 380 nm is 95.0% or higher. (F) The light reduction rate at a wavelength of 390 nm is 95.0% or higher. (G) The light reduction rate at a wavelength of 400 nm is 95.0% or higher. (H) The light reduction rate at a wavelength of 410 nm is 95.0% or higher. (I) The light reduction rate at a wavelength of 420 nm is 75.0% or less. (J) The light reduction rate at a wavelength of 430 nm is 30.0% or less. (K) The light reduction rate at a wavelength of 440 nm is 7.0% or less. (L) The light reduction rate at a wavelength of 450 nm is 2.0% or less.

2. The hard coat film was subjected to an irradiance of 500 W / m² under conditions of 63°C and 50% relative humidity. ２ The hard coat film according to claim 1, characterized in that, after 100 hours of exposure to ultraviolet light (lightfastness test), the absolute value of the rate of change (Δ%) of light transmittance at each wavelength, calculated by the following formula 2, satisfies the following conditions (M) to (W). Equation 2) Percentage change in light transmittance at each wavelength (Δ%) = Transmittance at that wavelength after the lightfastness test of the hard coat film - Transmittance at that wavelength before the lightfastness test of the hard coat film (M) The absolute value of the rate of change in light transmittance at a wavelength of 350 nm is 1.0% or less. (N) The absolute value of the rate of change of light transmittance at a wavelength of 360 nm is 1.0% or less. (O) The absolute value of the rate of change of light transmittance at a wavelength of 370 nm is 1.0% or less. (P) The absolute value of the rate of change of light transmittance at a wavelength of 380 nm is 1.0% or less. (Q) The absolute value of the rate of change in light transmittance at a wavelength of 390 nm is 5.0% or less. (R) The absolute value of the rate of change of light transmittance at a wavelength of 400 nm is 10.0% or less. (S) The absolute value of the rate of change of light transmittance at a wavelength of 410 nm is 30.0% or less. (T) The absolute value of the rate of change of light transmittance at a wavelength of 420 nm is 30.0% or less. (U) The absolute value of the rate of change of light transmittance at a wavelength of 430 nm is 10.0% or less. (V) The absolute value of the rate of change of light transmittance at a wavelength of 440 nm is 5.0% or less. (W) The absolute value of the rate of change of light transmittance at a wavelength of 450 nm is 5.0% or less.

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