JP2023096388A - hard coat film - Google Patents

Abstract

To provide a hard coat film that can prevent a display from being broken even in a case where a local external force is applied while having favorable hardness and scratch resistance.SOLUTION: A hard coat film 10 includes a base material film 12, and a hard coat layer 14 formed on a surface of the base material film 12. The hard coat layer 14 is formed of a cured product of a resin composition containing an ionization radiation curable resin and a damping property-imparting agent.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a hard coat film, and more particularly to a hard coat film used on the display surface of a liquid crystal display, an organic EL display, a touch panel provided in a smart phone, or the like.

Hard coat films are used for the purpose of protecting displays of image display devices such as liquid crystal display devices and organic EL display devices. 2. Description of the Related Art In recent years, in the field of image display devices, attention has been focused on flexible displays that can maintain display functions even when bent and can be repeatedly bent for use. Foldable displays that can be folded, rollable displays that can be rolled into a cylinder, and the like are known as flexible displays. Flexible displays are expected to be used for portable terminals such as smart phones and tablet terminals, and stationary displays that can be stored. As the cover window of the flexible display, a flexible ultra-thin glass film (UTG) or a plastic film is used in place of the plate-like glass substrate that has been widely used in conventional display devices.

Since UTG and plastic films are more easily scratched than glass substrates, the demand for hard coat films having a hard coat layer formed thereon is increasing in order to protect the surfaces of UTG and plastic films. A hard coat film is often laminated to the front window of a display, a retardation film, or the like via an optical adhesive layer (OCA). For example, Patent Document 1 discloses a hard coat film in which a hard coat layer is laminated on a polyimide film.

JP 2018-122583 A

In the flexible display described above, since the surface is not covered with a glass substrate, the display is relatively easily damaged when a local external force is applied, such as when a sharp object such as a ballpoint pen collides with it. There is a problem that there is a possibility that
The problem to be solved by the present invention is to provide a hard coat film that can suppress damage to a display even when a local external force is applied while having good hardness and scratch resistance.

The hard coat film according to the present invention has the following structure in order to achieve the above object.
The hard coat film according to the present invention has a base film and a hard coat layer formed on the surface of the base film, and the hard coat layer comprises an ionizing radiation curable resin and an attenuation-imparting It is formed from a cured product of a resin composition containing an agent.

Here, the attenuating agent may be one or more compounds selected from the group consisting of diphenylamine-based compounds and bisphenol-based compounds. Further, the attenuation imparting agent is 4,4′-bis(α,α-dimethylbenzyl)diphenylamine, p-(p-toluenesulfonylamido)diphenylamine, octylated diphenylamine, 4,4′-butylidenebis(3-methyl -6-tert-butylphenol), 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 2,2′-methylenebis(4-methyl-6-tert-butylphenol), and 4,4′- It is preferably one or more compounds selected from the group consisting of thiobis(3-methyl-6-tert-butylphenol). The content of the attenuation imparting agent is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the ionizing radiation curable resin.

It is preferable to have a transparent adhesive layer on the surface opposite to the hard coat layer of the base film. Moreover, it is preferable to have a protective film on the surface of the hard coat layer.

The hard coat film according to the present invention has a base film and a hard coat layer formed on the surface of the base film, and the hard coat layer comprises an ionizing radiation curable resin and an attenuation-imparting Since it is formed from a cured product of a hard coat layer-forming composition containing a can be done.

Here, when the attenuation imparting agent is one or more compounds selected from the group consisting of diphenylamine-based compounds and bisphenol-based compounds, damage to the display is prevented when a local external force is applied. It is particularly excellent in suppressing effect. In addition, each compound listed above can be suitably applied as such an attenuation imparting agent. When the content of the attenuation imparting agent is 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the ionizing radiation curable resin, the hard coat layer has impact resistance and scratch resistance. Highly compatible.

When the base film has a transparent adhesive layer on the surface opposite to the hard coat layer, the hard coat film can be attached to the surface of the display with good adhesion and the glass of the display can be prevented from scattering. can. Further, when a protective film is provided on the surface of the hard coat layer, it is possible to prevent the surface of the hard coat layer from being scratched in the process of processing or laminating the hard coat film.

BRIEF DESCRIPTION OF THE DRAWINGS It is an example of the cross-sectional schematic diagram of the hard-coat film which concerns on 1st embodiment of this invention. It is an example of the cross-sectional schematic diagram of the hard-coat film which concerns on 2nd embodiment of this invention. It is an example of the cross-sectional schematic diagram of the hard-coat film which concerns on 3rd embodiment of this invention.

The present invention will be described in detail below.

[Hard coat film according to the first embodiment]
FIG. 1 is a cross-sectional view of a hard coat film according to a first embodiment of the invention. As shown in FIG. 1 , the hard coat film 10 according to the first embodiment of the present invention has a base film 12 and a hard coat layer 14 formed on the surface of the base film 12 .

<Base film>
A specific configuration of the base film 12 is not particularly limited as long as it has transparency. Examples of the base film 12 include transparent polymer films and glass films. Transparency means that the total light transmittance in the visible light wavelength region is 50% or more, and the total light transmittance is more preferably 85% or more. The total light transmittance can be measured according to JIS K7361-1 (1997). Although the thickness of the base film 12 is not particularly limited, it is preferably in the range of 12 μm or more and 200 μm or less from the viewpoints of handleability, colorless transparency, flexibility, and the like. More preferably 20 μm or more, particularly preferably 25 μm or more. Also, it is more preferably 100 μm or less, particularly preferably 80 μm or less. The term "film" generally refers to a film having a thickness of less than 0.25 mm. .25mm or more shall be included in "film".

When the base film 12 is a transparent polymer film, the polymer material constituting the base film 12 includes polyester resins such as polyethylene terephthalate resin and polyethylene naphthalate resin, polycarbonate resins, poly(meth)acrylate resins, Polystyrene resins, polyamide resins, polyimide resins, polyacrylonitrile resins, polypropylene resins, polyethylene resins, polycycloolefin resins, polyolefin resins such as cycloolefin copolymer resins, cellulose resins such as triacetyl cellulose resins and diacetyl cellulose resins, polyphenylene sulfide resins , polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, and the like. The polymeric material of the base film 12 may be composed of only one of these, or may be composed of a combination of two or more. Among them, polyethylene terephthalate resins, polyimide resins, aromatic polyamide resins, polycarbonate resins, poly(meth)acrylate resins, polycycloolefin resins, cycloolefin copolymer resins, and triacetyl cellulose are selected from the viewpoint of optical properties and durability. Resin is more preferred.

The substrate film 12 may be composed of a single layer composed of a layer containing one or more of the above polymer materials, or a layer containing one or more of the above polymer materials and a layer containing this polymer material. It may be composed of two or more layers, such as a layer containing one or more polymeric materials different from the layer.

<Hard coat layer>
The hard coat layer 14 is formed from a cured product of a resin composition for forming a hard coat layer containing an ionizing radiation curable resin and an attenuation imparting agent.

(Ionizing radiation curable resin)
The hard coat layer 14 is composed of a cured product of a curable composition containing an ionizing radiation curable resin from the viewpoint of high hardness, high flexibility, productivity, and the like. Ionizing radiation means electromagnetic waves or charged particle beams that have energy quanta capable of polymerizing or cross-linking molecules. Examples of ionizing radiation include electromagnetic waves such as ultraviolet rays (UV), X-rays and γ-rays, charged particle beams such as α-rays, electron beams (EB) and ion beams. Among these, ultraviolet rays (UV) are particularly preferable from the viewpoint of productivity.

The ionizing radiation curable resin contains at least one of monomers, oligomers and prepolymers having ionizing radiation reactive groups. Reactive groups reactive to ionizing radiation include radical polymerization type reactive groups having ethylenically unsaturated bonds such as acryloyl groups, methacryloyl groups, allyl groups and vinyl groups, and cationic polymerization type reactive groups such as oxetanyl groups. etc. Among these, acryloyl group, methacryloyl group and oxetanyl group are more preferable, and acryloyl group and methacryloyl group are particularly preferable. That is, (meth)acrylate is particularly preferable as the ionizing radiation-curable resin. In this specification, "(meth)acrylate" means "at least one of acrylate and methacrylate". "(Meth)acryloyl" means "at least one of acryloyl and methacryloyl". "(Meth)acrylic" means "at least one of acrylic and methacrylic".

The (meth)acrylate that constitutes the ionizing radiation curable resin may be composed of only monofunctional (meth)acrylate, may be composed only of polyfunctional (meth)acrylate, or may be composed of monofunctional (meth)acrylate. ) may be composed of a combination of an acrylate and a polyfunctional (meth)acrylate. More preferably, the ionizing radiation-curable composition contains a polyfunctional (meth)acrylate.

(Meth)acrylates include urethane (meth)acrylates, silicone (meth)acrylates, alkyl (meth)acrylates, and aryl (meth)acrylates. Among them, urethane (meth)acrylate is particularly preferable from the viewpoint of being relatively flexible and improving the flexibility of the hard coat film 10 .

Monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, and isobutyl (meth)acrylate. , t-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl ( meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate ) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, bornyl (meth) acrylate, tricyclodeca Nil (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 1-naphthylmethyl (meth)acrylate, 2-naphthylmethyl (meth)acrylate ) acrylate, phenoxyethyl (meth) acrylate, phenoxy-2-methylethyl (meth) acrylate, phenoxyethoxyethyl (meth) acrylate, 3-phenoxy-2-hydroxypropyl (meth) acrylate, 2-phenylphenoxyethyl (meth) Acrylates, 4-phenylphenoxyethyl (meth)acrylate, 3-(2-phenylphenyl)-2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2- Hydroxybutyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxyethylene glycol (meth) ) acrylate, ethoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, and the like.

Polyfunctional (meth)acrylates include bifunctional (meth)acrylates, trifunctional (meth)acrylates, tetrafunctional (meth)acrylates, and the like. More specifically, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, Diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate , pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol tetra(meth)acrylate, tripentaerythritol penta(meth)acrylate ) acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate and the like.

Oligomers and prepolymers include urethane (meth)acrylates, silicone (meth)acrylates, alkyl (meth)acrylates, and aryl (meth)acrylates. Other examples include polymers having ionizing radiation reactive groups.

The (meth)acrylate of the ionizing radiation-curable resin may be composed of one kind of the above-mentioned (meth)acrylates alone, or may be composed of two or more kinds.

(Attenuation imparting agent)
The attenuation imparting agent contributes to the improvement of the impact resistance of the hard coat layer by being contained in the hard coat layer.

The damping agent is a substance with polarization (positive and negative bias) called a dipole that rotates (at its resonance frequency) when energy such as sound, vibration, electromagnetic waves, or impact is applied as an external force. When a material is exposed to energy such as sound, vibration, or electromagnetic waves, the dipoles move or rotate, and at that time frictional heat is generated by collisions between the molecular chains of the matrix and between the dipoles, which is converted into thermal energy. , the applied energy is attenuated. Its energy conversion efficiency depends on the magnitude of the dipole moment (dipole moment). For example, when water molecules (H ₂ O), which are said to have the highest dipole efficiency among substances, are irradiated with microwaves, the water molecules rotate and generate heat.

Diphenylamine-based compounds, bisphenol-based compounds, benzothiazole-based compounds, benzotriazole-based compounds, and benzophenone-based compounds are examples of attenuation imparting agents that have such an action and are suitable to be added to the composition that constitutes the hard coat layer 14. compound etc. can be mentioned. Among them, it is preferable to use one or more compounds selected from the group consisting of diphenylamine compounds and bisphenol compounds.

Diphenylamine compounds include 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, p-(p-toluenesulfonylamido)diphenylamine, octylated diphenylamine, and the like. On the other hand, bisphenol compounds include 4,4′-butylidenebis(3-methyl-6-tert-butylphenol), 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol) and the like. Among them, 4,4′-bis(α,α-dimethylbenzyl)diphenylamine, 4,4′-butylidenebis(3-methyl-6-tert- butylphenol) is particularly preferred.

A hard coat layer having impact resistance can be obtained by blending an attenuation imparting agent having a high dipole efficiency in a matrix composed of an ionizing radiation curable resin. In the impact-resistant hard coat layer 14 containing an attenuation imparting agent in this way, when an impact force is applied from the outside, the dipoles existing inside the resin matrix are displaced. Displacement of dipoles means that each dipole inside the resin matrix rotates or shifts out of phase.

It can be said that the arrangement state of the dipoles inside the resin matrix before impact force (impact energy) is applied is in an energetically stable state. However, when an impact force (impact energy) is applied, the dipoles existing inside the resin matrix are displaced, and as a result, each dipole inside the resin matrix is placed in an unstable state. Each dipole then tries to return to its original stable state. At this time, Joule heat is generated by the contact between the substance having dipoles and adjacent polymer chains or low molecules, and as a result, the energy added by the impact is converted into heat energy and disappears. It is believed that the effect of absorbing the impact force is produced through energy consumption due to the displacement of the dipoles inside the resin matrix and the subsequent restoring action of the dipoles.

The content of the attenuation imparting agent in the composition constituting the hard coat layer 14 is preferably 1 part by mass or more with respect to 100 parts by mass of the ionizing radiation curable resin. If it is 1 part by mass or more, impact resistance will be sufficient. From this point of view, it is more preferably 1.5 parts by mass or more, and still more preferably 2 parts by mass or more. On the other hand, the content of the attenuation imparting agent is preferably 20 parts by mass or less. When the amount is 20 parts by mass or less, the scratch resistance of the surface of the hard coat layer 14 can be improved. From this point of view, it is more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less. In the hard coat layer 14, the attenuation imparting agent is distributed in a state of being dispersed in the cured product of the ionizing radiation curable resin.

(other ingredients)
The composition curable by ionizing radiation that constitutes the hard coat layer 14 may or may not contain a polymer that is not cured by ionizing radiation in addition to a polymer that is cured by ionizing radiation. The composition that is cured by ionizing radiation may also contain a polymerization initiator. In addition, if necessary, additives that can be generally added to the curable composition may be included. Additives include dispersants, leveling agents, antifoaming agents, stabilizing agents, antifouling agents, antibacterial agents, flame retardants, slip agents, inorganic particles, resin particles and the like. Moreover, a solvent may be contained as necessary.

Examples of polymers that are not cured by ionizing radiation include thermoplastic resins and thermosetting resins. Examples of thermoplastic resins include polyester resins, polyether resins, polyolefin resins, polyamide resins, and (meth)acrylic resins. Thermosetting resins include unsaturated polyester resins, epoxy resins, alkyd resins, phenolic resins, and the like.

A photoinitiator is mentioned as a polymerization initiator. Examples of the photopolymerization initiator include alkylphenone-based, acylphosphine oxide-based, and oxime ester-based photopolymerization initiators. Alkylphenone-based photopolymerization initiators include 2,2′-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl- Propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-( 2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzylmethyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-(4-morpholino phenyl)-1-butanone, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, N,N-dimethylaminoacetophenone and the like. Acylphosphine oxide photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2 , 4,4-trimethyl-pentylphosphine oxide. Examples of oxime ester photopolymerization initiators include 1,2-octanedione, 1-[4-(phenylthio)phenyl]-2-(O-benzoyloxime), ethanone-1-[9-ethyl-6-(2- methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime) and the like. These photopolymerization initiators may be used alone, or two or more of them may be used in combination.

The content of the photopolymerization initiator is preferably 0.1% by mass or more, more preferably 1% by mass or more, based on the total amount of the composition that is cured by ionizing radiation. On the other hand, its content should be 10% by mass or less, more preferably 5% by mass or less.

The inorganic particles and resin particles are added to the hard coat layer 14 for the purpose of, for example, preventing blocking of the hard coat layer 14, suppressing wrinkles, and improving surface hardness. By forming fine surface irregularities on the hard coat layer 14 with the added inorganic particles and resin particles, when the hard coat film 10 is wound in a roll or stacked, it is easy to suppress blocking where the front and back surfaces adhere to each other. .

The ionizing radiation-curable composition may be diluted with a solvent. Examples of solvents include ethanol, isopropyl alcohol (IPA), n-butyl alcohol (NBA), ethylene glycol monomethyl ether (EGM), ethylene glycol monoisopropyl ether (IPG), propylene glycol monomethyl ether (PGM), diethylene glycol monobutyl ether, and the like. Alcohol-based solvents, ketone-based solvents such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclohexanone and acetone, aromatic solvents such as toluene and xylene, ethyl acetate (EtAc), propyl acetate, isopropyl acetate, butyl acetate Ester solvents such as (BuAc), and amide solvents such as N-methylpyrrolidone, acetamide, and dimethylformamide. These may be used individually by 1 type as a solvent, and may be used in combination of 2 or more types.

The solid content concentration (concentration of components other than the solvent) of the composition that is cured by ionizing radiation may be appropriately determined in consideration of coatability, film thickness, and the like. For example, it may be 1% by mass or more, 1.5% by mass or more, or 2% by mass or more. Also, it may be 90% by mass or less, 80% by mass or less, or 70% by mass or less.

(Thickness and hardness of hard coat layer)
Although the thickness of the hard coat layer 14 is not particularly limited, it is preferably 0.5 μm or more from the viewpoint of having sufficient hardness. It is more preferably 1.0 μm or more, still more preferably 3.0 μm or more. In addition, from the viewpoint of easily suppressing curling due to a difference in heat shrinkage with the base film 12, the thickness is preferably 10 μm or less. It is more preferably 8.0 μm or less, still more preferably 6.0 μm or less. The thickness of the hard coat layer 14 is the thickness of the relatively smooth portion in the thickness direction where there are no irregularities caused by inorganic particles or resin particles.

The hard coat layer 14 preferably has a pencil hardness of HB or higher. More preferably H or higher. The pencil hardness of the hard coat layer 14 referred to here is the pencil hardness of the surface of the hard coat layer 14 formed on one side of the base film 12, and the transparent adhesive layer 22 ( (described later) is not formed. The pencil hardness of the hard coat layer 14 can be measured according to JIS K 5600-5-4.

<Method for producing hard coat film>
The hard coat film 10 is formed by applying a composition to be the hard coat layer 14 on the surface of the base film 12, drying it as necessary, and curing it by irradiation with ionizing radiation such as ultraviolet irradiation. can be manufactured by forming a hard coat layer 14 on the surface of the At this time, in order to improve the adhesion between the base film 12 and the hard coat layer 14, the surface of the base film 12 may be subjected to surface treatment before coating. Examples of surface treatment include corona treatment, plasma treatment, hot air treatment, ozone treatment, and ultraviolet treatment.

For coating of the composition forming the hard coat layer 14, for example, a reverse gravure coating method, a direct gravure coating method, a die coating method, a bar coating method, a wire bar coating method, a roll coating method, a spin coating method, and a dip coating method. , a spray coating method, a knife coating method and a kiss coating method, and various printing methods such as an inkjet method, offset printing, screen printing and flexographic printing.

The conditions for the drying step are not particularly limited as long as the solvent and the like used in the coating liquid can be removed. In particular, the drying temperature is preferably 50°C or higher and 120°C or lower.

A high-pressure mercury lamp, an electrodeless (microwave type) lamp, a xenon lamp, a metal halide lamp, or any other ultraviolet irradiation device can be used for ultraviolet irradiation. UV irradiation may be performed under an inert gas atmosphere such as nitrogen, if necessary. The amount of ultraviolet irradiation is not particularly limited, but is preferably 50-800 mJ/cm ² , more preferably 100-300 mJ/cm ² .

The hard coat film 10 having the above configuration is a hard coat film having a base film 12 and a hard coat layer 14 formed on the surface of the base film 12, wherein the hard coat layer 14 is a binder resin. In addition, since it contains an attenuation imparting agent, the hard coat film 10 having excellent impact resistance and scratch resistance can be obtained.

[Hard coat film according to another embodiment]
The hard coat film according to the present invention is not limited to the configuration of the hard coat film 10 according to the first embodiment. Other embodiments of the hard coat film according to the present invention are described below.

<Second embodiment>
FIG. 2 shows a form having a transparent adhesive layer 22 as an optical adhesive layer (OCA) as the hard coat film 20 according to the second embodiment. A hard coat film 20 according to the second embodiment has a base film 12 and a hard coat layer 14 formed on one surface of the base film 12 . Moreover, it has a transparent adhesive layer 22 on the other surface of the base film 12 . A release film 24 is arranged on the surface of the transparent adhesive layer 22 as necessary. The release film 24 functions as a protective layer for the transparent adhesive layer 22 before use, and is peeled off from the transparent adhesive layer 22 during use.

The hard coat film 20 according to the second embodiment differs from the hard coat film 10 according to the first embodiment in that it has a transparent adhesive layer 22 on the other surface of the base film 12. are the same as those of the hard coat film 10 according to the first embodiment, and descriptions of the same configurations are omitted.

The transparent adhesive layer 22 is for attaching the hard coat film 20 to the surface of the display with good adhesion. Moreover, the hard coat film 20 has the effect of preventing scattering of the display glass by having the transparent adhesive layer 22 . That is, the hard coat film 20 also has a function as a scattering prevention film.

The adhesive composition forming the transparent adhesive layer 22 can contain known adhesive resins such as (meth)acrylic adhesives, silicone adhesives, and urethane adhesives. Among them, (meth)acrylic adhesives are preferable from the viewpoint of optical transparency and heat resistance. The adhesive composition preferably contains a cross-linking agent in order to increase cohesion of the transparent adhesive layer 22 . Examples of cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, and chelate-based cross-linking agents.

The adhesive composition may contain additives as necessary. Examples of additives include known additives such as plasticizers, silane coupling agents, surfactants, antioxidants, fillers, curing accelerators and curing retarders. Moreover, from the viewpoint of productivity, etc., it may be diluted using an organic solvent.

Although the film thickness of the transparent adhesive layer 22 is not particularly limited, it is preferably 5 μm or more, more preferably 10 μm or more. Also, the film thickness is preferably 100 μm or less, more preferably 50 μm or less.

The transparent adhesive layer 22 is formed by directly applying an adhesive composition on the other surface of the base film 12, or by applying an adhesive composition on the surface of the release film 24, and then applying the adhesive composition to the substrate. A method of transferring onto the other surface of the material film 12, applying an adhesive composition on the surface of the first release film to form it, then bonding the second release film, It can be formed by a method of peeling off the mold film and transferring it onto the other surface of the base film 12 .

The shear storage modulus of the transparent adhesive layer 22 at 25° C. is preferably 1.0×10 ⁴ Pa or more, more preferably 2.0×10 ⁴ Pa or more, still more preferably 5.0×10 ⁴ Pa or more, especially It is preferably 1.0×10 ⁵ Pa or more, preferably 3.0×10 ⁶ Pa or less, more preferably 2.0×10 ⁶ Pa or less, and even more preferably 1.0×10 ⁶ Pa or less. When the shear storage elastic modulus (G′) is 1.0×10 ⁴ Pa or more, the transparent adhesive layer 22 has appropriate flexibility and shape followability, and good impact resistance. If the pressure is 3.0×10 ⁶ Pa or less, the cohesive force and adhesiveness of the transparent adhesive layer 22 become better.

From the viewpoint of suppressing lifting and peeling, the transparent adhesive layer 22 preferably has an adhesive force to an adherend of 4 N/25 mm or more. It is more preferably 6 N/25 mm or more, still more preferably 10 N/25 mm or more.

<Third embodiment>
FIG. 3 shows a form having a protective film as the hard coat film 30 according to the third embodiment. The hard coat film 30 according to the third embodiment comprises a base film 12, a hard coat layer 14 formed on one surface of the base film 12, and an adhesive layer 26 on the surface of the hard coat layer 14. and a protective film 28 disposed therebetween. Moreover, it has a transparent adhesive layer 22 on the other surface of the base film 12 . A release film 24 is arranged on the surface of the transparent adhesive layer 22 as necessary.

The hard coat film 30 according to the third embodiment differs from the hard coat film 20 according to the second embodiment in that it has a protective film 28 on the surface of the hard coat layer 14 via an adhesive layer 26. Other than this, it is the same as the hard coat film 20 according to the second embodiment, and the description of the same configuration is omitted.

The protective film 28 can prevent the surface of the hard coat layer 14 from being scratched when the hard coat film 30 is handled, for example, by continuous processing such as a roll process or bonding to a touch panel. be. The protective film 28 is attached to the surface of the hard coat layer 14 via the adhesive layer 26 . The protective film 28 is peeled off from the surface of the low refractive index layer 14 together with the adhesive layer 26 after the hard coat film 30 has been processed or pasted. Therefore, in the adhesive layer 26, the adhesive strength between the protective film 28 and the adhesive layer 26 is stronger than the adhesive strength between the hard coat layer 14 and the adhesive layer 26. 26 is adjusted to an adhesive force that allows interfacial peeling.

The materials composing the protective film 28 can be appropriately selected from the materials exemplified as the materials composing the base film 12 . The thickness of the protective film 28 is not particularly limited, but can be in the range of 2 μm or more, 500 μm or less, and further 200 μm or less.

The adhesive that forms the adhesive layer 26 is not particularly limited, and (meth)acrylic adhesives, silicone adhesives, urethane adhesives, and the like can be suitably used. In particular, acrylic pressure-sensitive adhesives are suitable because they are excellent in transparency and heat resistance. The (meth)acrylic pressure-sensitive adhesive is preferably formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer and a cross-linking agent.

(Meth)acrylic polymers are homopolymers or copolymers of (meth)acrylic monomers. (Meth)acrylic monomers include alkyl group-containing (meth)acrylic monomers, carboxyl group-containing (meth)acrylic monomers, and hydroxyl group-containing (meth)acrylic monomers.

Examples of alkyl group-containing (meth)acrylic monomers include (meth)acrylic monomers having an alkyl group having 2 to 30 carbon atoms. The alkyl group having 2 to 30 carbon atoms may be linear, branched, or cyclic. More specifically, the alkyl group-containing (meth)acrylic monomer includes, for example, isostearyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, (meth)acrylic acid ) Decyl acrylate, isononyl (meth) acrylate, nonyl (meth) acrylate, isooctyl (meth) acrylate, octyl (meth) acrylate, isobutyl (meth) acrylate, n-butyl (meth) acrylate, ( meth)pentyl acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, propyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, etc. is mentioned.

Carboxyl group-containing (meth)acrylic monomers include (meth)acrylic acid, carboxyethyl (meth)acrylate, and carboxypentyl (meth)acrylate. The carboxyl group may be located at the end of the alkyl chain or in the middle of the alkyl chain.

Examples of hydroxyl group-containing (meth)acrylic monomers include hydroxylauryl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxybutyl (meth)acrylate, Hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate and the like. The hydroxyl group may be located at the terminal of the alkyl chain or may be located in the middle of the alkyl chain.

The (meth)acrylic monomer forming the (meth)acrylic polymer may be one of the above, or may be a combination of two or more.

Examples of cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, metal chelate-based cross-linking agents, metal alkoxide-based cross-linking agents, carbodiimide-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, and melamine-based cross-linking agents. . The cross-linking agent may be used alone or in combination of two or more.

The pressure-sensitive adhesive composition may contain other additives in addition to the (meth)acrylic polymer and the cross-linking agent. Other additives include cross-linking accelerators, cross-linking retarders, tackifying resins (tackifiers), antistatic agents, silane coupling agents, plasticizers, release aids, pigments, dyes, wetting agents, thickeners. , ultraviolet absorbers, preservatives, antioxidants, metal deactivators, alkylating agents, flame retardants and the like. These are appropriately selected and used according to the application and purpose of use of the pressure-sensitive adhesive.

Although the film thickness of the adhesive layer 26 is not particularly limited, it is preferably 1 μm or more, more preferably 2 μm or more. Also, the film thickness is preferably 10 μm or less, more preferably 7 μm or less.

Although the embodiments of the present invention have been described above, the present invention is by no means limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, it is described that the surface of the base film 12 may be subjected to surface treatment. good too. Various functional layers such as a gas barrier property improving layer, an antistatic layer, and an oligomer block layer may be previously provided on the surface of the base film 12 before the hard coat layer 14 is formed. Various functional layers such as a transparent conductive layer, an antiglare layer, an antireflection layer, an antistatic layer, an antifouling layer, and an antifogging layer may be provided on the surface of the hard coat layer 14 .

The present invention will be described in detail below using examples and comparative examples. Unless otherwise specified, each step related to sample preparation and evaluation was performed at room temperature in the atmosphere.

<Preparation of composition for forming hard coat layer>
(Examples 1 and 2)
4,4'-butylidenebis(3- Methyl-6-tert-butylphenol) (“Nocrac NS-30” manufactured by Ouchi Shinko Kagaku, melting point: 208° C.) and a photopolymerization initiator “Omnirad 127” (manufactured by IGM Resins B.V.) were added to form a hard A coating layer-forming composition was prepared. At this time, the amount of the attenuation imparting agent is as shown in Table 1 (parts by mass with respect to 100 parts by mass of the solid content of the ultraviolet curable resin), and the amount of the photopolymerization initiator is the amount of the ultraviolet curable resin and the attenuation. It was made to be 3% by mass with respect to 100% by mass of the solid content of the property-imparting agent. Further, ethyl acetate was added to the composition for forming a hard coat layer so that the solid content concentration was 42.5% by mass.

(Examples 3-4)
<Preparation of composition for forming hard coat layer>
4,4′-bis(α,α-dimethylbenzyl)diphenylamine (Ouchi Shinko Kagaku “Nocrac CD”, melting point: 90° C.) was used as attenuation imparting agent 2 instead of attenuation imparting agent 1. Hard coat layer-forming compositions of Examples 3 and 4 were prepared in the same manner as in Examples 1 and 2 except for the above.

(Comparative example 1)
A composition for forming a hard coat layer of Comparative Example 1 was prepared in the same manner as in Examples 1 to 4, except that no attenuation imparting agent was used.

<Formation of hard coat layer>
Each hard coat layer forming composition prepared above was applied to a substrate film (Toyobo polyethylene terephthalate film "TA048", thickness 80 μm) using a #12 wire bar, and dried at 80° C. for 60 seconds. After that, a hard coat layer (thickness: 5 μm) was formed by irradiating ultraviolet light with a light amount of 200 mJ/cm ² using a high-pressure mercury lamp. As described above, hard coat films according to Examples 1 to 4 were produced.

<Evaluation method>
(film thickness)
The film thickness of the hard coat layer was measured by spectral interferometry using "Filmetrics F20 film thickness measurement system" manufactured by Filmetrics.

(Steel wool test)
A steel wool test was performed to evaluate the scratch resistance of the hard coat layer. Steel wool #0000 (manufactured by Nippon Steel Wool Co., Ltd.) fixed to a friction element of 20 mm × 20 mm using a Gakushin type rubbing fastness tester (AB-301 COLOR FASTNESS RUBBING TESTER manufactured by Tester Sangyo) is coated on a hard coat film. It was placed on the surface of the hard coat layer and reciprocated. The stroke length of the test stand was 120 mm, the reciprocation speed of the test stand was 60 reciprocations/minute, and the load was 500 g/cm. The sample was visually observed every 100 reciprocations, and the maximum number of times when no damage of 10 mm or more in length was observed was taken as the evaluation value of the steel wool test.

(Pencil hardness of hard coat layer)
The hardness of the hard coat layer constituting the hard coat film was measured by the method specified in JIS K 5600-5-4 using a pencil hardness tester (manufactured by Tester Sangyo). The test load was 500 g, and the test was repeated 5 times while changing the hardness of the pencil. It was set as an evaluation value.

(Pen drop test)
A pen drop test was performed to evaluate the impact resistance of the hard coat layer. The hard coat film was laminated on the opposite side of the hard coat layer to a glass plate with a thickness of 2 mm using an optical adhesive sheet (“S-PS58” manufactured by Higashiyama Film Co., Ltd., thickness 25 μm) using a hand roller. A 2 kg roller was made to reciprocate once and crimped. Next, the hard coat layer was placed on a SUS plate with a thickness of 5 mm, and a cylinder with a pencil-shaped tip (made of SUS304, diameter φ 9 mm, total length 49.8 mm, taper angle 25 °, tip R (radius ) 0.8 mm, weight 19.4 g) was dropped from a position 400 mm high from the hard coat film such that the sharpened tip collided perpendicularly with the hard coat layer. Five minutes after the collision test, the depth of the dents formed on the surface of the hard coat film due to the collision was measured using a 3D measurement laser microscope ("LEXT OLS5000" manufactured by Olympus, objective lens magnification of 10 times). In general, if the depth of the pen drop dent is 50 μm or less, it can be said that the hard coat layer has high impact resistance.

<Evaluation results>
Table 1 below summarizes the component composition of the hard coat layer of each sample and the evaluation results.

According to Table 1, since Comparative Example 1 did not contain an attenuation imparting agent in the hard coat layer, when a local external force was applied, a deep pen drop dent exceeding 50 μm was generated. On the other hand, in Examples 1 to 4, in which the hard coat layer contains the attenuation imparting agent, the depth of the pen drop dent is suppressed to 50 μm or less, and the attenuation imparting agent is added to the hard coat layer. , the impact resistance of the hard coat layer is improved. In Examples 1 to 4 and Comparative Example 1, the evaluation results of the steel wool test and the pencil hardness were almost the same. is confirmed to be maintained.

A bisphenol-based compound was used in Examples 1 and 2, and a diphenylamine-based compound was used in Examples 3 and 4, as the attenuation imparting agent. The effect of improving the impact resistance of the hard coat layer, which is evaluated as a reduction in the depth of the layer, is obtained. Also, when any of the attenuation imparting agents is used, by increasing the amount of the attenuation imparting agent added from 2 parts by mass (Examples 1 and 3) to 10 parts by mass (Examples 2 and 4), The scratch resistance improvement effect is particularly large. In particular, the effect is remarkable in Example 4 using a diphenylamine-based attenuation imparting agent.

As described above, it has a substrate film and a hard coat layer formed on the surface of the substrate film, and the hard coat layer comprises an ionizing radiation curable resin and a hard coating containing an attenuation imparting agent. The hard coat film formed from the cured product of the coat layer-forming composition can suppress damage to the display even when a local external force is applied while having good hardness and scratch resistance.

Although the embodiments of the present invention have been described above, the present invention is by no means limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

10, 20, 30 Hard coat film 12 Base film 14 Hard coat layer 22 Transparent adhesive layer 24 Release film 26 Adhesive layer 28 Protective film

Claims (6)

Having a base film and a hard coat layer formed on the surface of the base film,
A hard coat film, wherein the hard coat layer is formed from a cured product of a resin composition containing an ionizing radiation-curable resin and an attenuation imparting agent. 2. The hard coat film according to claim 1, wherein said damping agent is one or more compounds selected from the group consisting of diphenylamine compounds and bisphenol compounds. The attenuation imparting agent is 4,4′-bis(α,α-dimethylbenzyl)diphenylamine, p-(p-toluenesulfonylamido)diphenylamine, octylated diphenylamine, 4,4′-butylidenebis(3-methyl-6 -tert-butylphenol), 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 2,2′-methylenebis(4-methyl-6-tert-butylphenol), and 4,4′-thiobis( 3-methyl-6-tert-butylphenol). The hardware according to any one of claims 1 to 3, wherein the content of the attenuation imparting agent is 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the ionizing radiation curable resin. coat film. The hard coat film according to any one of claims 1 to 4, which has a transparent adhesive layer on the surface opposite to the hard coat layer of the base film. The hard coat film according to any one of claims 1 to 5, which has a protective film on the surface of the hard coat layer.

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