JP4859128B2 - HARD COAT FILM, HARD COAT FILM LAMINATE, AND IMAGE DISPLAY DEVICE - Google Patents

Description

  The present invention relates to a hard coat film and a hard coat film laminate used for a liquid crystal display device and the like, and an image display device.

Conventionally, a hard coat film may be provided on the screen in order to prevent the screen of the image display device from being damaged.
As the hard coat film, for example, a transparent plastic film provided with a hard coat layer is known.
The hard coat layer is usually a thin coating film of about 2 to 10 μm formed on a transparent plastic film using a hard coat resin such as an ionizing radiation curable resin such as a thermosetting resin or an ultraviolet curable resin. It is composed of
However, even if the hard coat resin can form a coating film having a pencil hardness of 4H or more when coated on glass, the thickness of the coating film is sufficient when applied to a transparent plastic film. Therefore, under the influence of the transparent plastic film, the surface hardness of the formed hard coat layer is about 3H pencil hardness. For this reason, high hardness of the hard coat layer formed on the transparent plastic film is required.

As a means of improving the hardness of the hard coat layer, it is conceivable to simply increase the thickness of the hard coat layer, but this means that the hard coat layer is liable to crack and peel, and at the same time, the hard coat layer is cured and shrunk. The curl due to becomes large and cannot be used practically.
Further, in order to realize high hardness of the hard coat film, Patent Documents 1 to 4 have been proposed as methods for solving the problems such as cracking and peeling of the hard coat layer and curling due to curing shrinkage.

  Patent Document 1 discloses a protective film for a polarizing plate in which a cured coating layer made of a composition containing an ultraviolet curable polyol acrylate resin is formed on at least one surface of a transparent plastic film, and the ultraviolet curable polyol acrylate resin is disclosed. It is disclosed to use dipentaerythritol hexaacrylate. However, a resin whose main component is dipentaerythritol hexaacrylate can secure a hardness of pencil hardness of 4H or more by forming a coating film having a thickness of 10 μm or more on a plastic film. It is difficult to suppress these simultaneously.

  In Patent Document 2, a hard layer formed by providing a buffer layer composed of one layer or multiple layers having a thickness of 3 to 50 μm on at least one surface of a plastic film, and forming a hard coat layer having a thickness of 3 to 15 μm on the buffer layer. A hard coat film having a pencil hardness of 4H to 8H as a whole is disclosed in which the pencil hardness of each of the plastic film, the buffer layer and the hard coat layer has an increased value in this order. . However, such a two-layer configuration results in poor productivity and increases costs.

  In Patent Document 3, a cured resin layer containing inorganic or organic internally crosslinked ultrafine particles is provided as a first hard coat layer on a base material, and then internally crosslinked particles are further inorganic or organic as a second hard coat layer. A hard coat film provided with a cured resin coating layer provided with a thin film of clear cured resin not contained is disclosed. However, since this hard coat film also has a two-layer structure, there are problems such as poor productivity as in Patent Document 2.

  Patent Document 4 discloses a hard coat film in which at least one hard coat layer is formed on at least one surface of a transparent substrate, and the hard coat layer forming material is 100 parts by weight of polyester acrylate or urethane acrylate resin. A hard coat film containing 20 to 80 parts by weight of inorganic fine particles per hit, the thickness of the entire hard coat layer is 10 μm to 50 μm, and the pencil hardness of the surface is 4H or more is disclosed. However, when a hard coat layer is formed on a transparent substrate with a thickness of 10 μm or more, if the hard coat forming material is polyester acrylate or urethane acrylate containing inorganic fine particles, sufficient hardness is secured and curling is suppressed due to cure shrinkage. It is difficult to balance.

JP-A-9-113728 JP-A-11-300873 JP 2000-52472 A JP2000-112379A

  An object of the present invention is to provide a thin hard coat film capable of obtaining good hard coat characteristics while suppressing the occurrence of curling of the film when a hard coat layer is formed on a transparent film. Moreover, it aims at providing the laminated body and image display apparatus which have this hard coat film.

As a result of intensive studies, the present inventors have found that the above object can be achieved by using a plate-shaped glass fine particle and orienting it in a substantially parallel manner to a transparent film.
The hard coat film of the present invention is provided with a hard coat layer mainly composed of a resin curable by heat or ionizing radiation on at least one surface of the transparent film, and the hard coat layer is subjected to a silane coupling treatment. The plate-like glass fine particles include a plate-like glass fine particle, and the plate-like glass fine particle has an aspect ratio calculated by [maximum length on the upper surface of the plate-like glass fine particle / thickness of the plate-like glass fine particle] of 15 or more, The fine particles are fixed in a state of being oriented substantially parallel to the surface of the transparent film.

  Since the hard coat film contains plate-like glass particles subjected to a silane coupling process having excellent adhesion to the resin, the hard coat layer can be formed with high hardness (for example, pencil hardness of 4H or more). it can. Furthermore, since the plate-like glass fine particles are fixed in a state of being oriented in parallel to the surface of the transparent film, the curing shrinkage of the resin can be suppressed, and the curling of the film can be effectively suppressed.

In a preferred hard coat film of the present invention, the coupling agent used for the silane coupling treatment contains a vinyl silane coupling agent.
In another preferred hard coat film of the present invention, the hard coat layer has a thickness of 8 to 20 μm .
In another preferred hard coat film of the present invention, the plate-like glass fine particles have a thickness of 0.4 μm to 2.0 μm and a maximum length of 10 μm to 50 μm.
In another preferred hard coat film of the present invention, the hard coat layer has a pencil hardness of 4H or more.
Another preferable hard coat film of the present invention is a protective film in which the transparent film is laminated on the polarizer or the polarizer.

Furthermore, in the hard coat film laminate of the present invention, any one of the above hard coat films is laminated on at least one surface of the optical film.
In a preferred hard coat film laminate of the present invention, the optical film is a polarizer or a polarizing plate.

  Moreover, the image display apparatus of the present invention includes any one of the above hard coat films or any one of the above hard coat film laminates.

Since the hard coat film of the present invention is provided with a hard coat layer having plate-like glass fine particles oriented substantially parallel to the transparent film, the surface is excellent in surface hardness and curling can be suppressed. Therefore, according to the present invention, a hard coat film excellent in scratch resistance and handleability can be provided.
Moreover, the laminated body which has this hard coat film is excellent in scratch resistance and handleability, and is suitable for optical applications.

<Hard coat film>
(About the structure of the hard coat film)
FIG. 1A is a reference perspective view showing a hard coat film in which the hard coat layer of the present invention is provided on one side of the transparent film, and FIG. 1B is a diagram in which the hard coat layer is provided on both sides of the transparent film. It is a reference perspective view which shows the obtained hard coat film.
FIG. 2 is an enlarged view of a cut surface obtained by cutting the hard coat film of FIG. 1A in one direction (for example, the width direction).

1 and 2, 1 indicates a hard coat film, 2 indicates a transparent film, and 3 indicates a hard coat layer.
The hard coat film 1 is formed in a predetermined shape (for example, a rectangular shape when viewed from above), and has a transparent film 2 as a base film. The hard coat layer 3 includes a plurality of plate glass fine particles 10 and a binder 4 for fixing the plate glass fine particles 10, and the surface of the hard coat layer 3 is formed in a substantially smooth surface.
The plurality of plate-like glass particles 10 are fixed by the binder 4 in a state where the upper surface 11 of the plate-like glass particles 10 is oriented substantially parallel to the surface 21 of the transparent film 2. However, in the present invention, not all the plate-like glass fine particles 10 included in the hard coat layer 3 are fixed in a substantially parallel state, and some of the plate-like glass fine particles 10 are not transparent. The case where it is fixed in a slightly tilted state with respect to the surface 21 of this is also included.
Further, the plate-like glass fine particles 10 include not only a state where a plurality of plate-like glass particles are stacked one above the other but also a state where they are not overlapped.

(About transparent film)
The transparent film can be used without particular limitation as long as it has excellent light transmittance of visible light and excellent transparency. The light transmittance in visible light of the transparent film is preferably 80% or more, more preferably 90% or more. However, the light transmittance means a Y value obtained by correcting the visibility based on spectrum data measured with a spectrophotometer (product name: U-4100 type, manufactured by Hitachi, Ltd.) with a film thickness of 100 μm.
The haze value of the transparent film is preferably 3% or less, more preferably 1% or less. However, in the present invention, the haze value is a value measured according to JIS-K7105.
Specifically, as the transparent film, for example, ester polymers such as polyethylene terephthalate and polyethylene naphthalate; cellulose polymers such as diacetyl cellulose and triacetyl cellulose; carbonate polymers; acrylic polymers such as polymethyl methacrylate; polystyrene Styrene polymers such as acrylonitrile / styrene copolymers; polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, olefin polymers such as ethylene / propylene copolymers; vinyl chloride polymers; amides such as nylon and aromatic polyamide Polymer; imide polymer; sulfone polymer; polyethersulfone polymer; polyetheretherketone polymer, polyphenylenesulfur System polymers; vinyl alcohol-based polymer; like plastic film composed mainly of a transparent polymer such as an epoxy-based polymer; vinylidene chloride polymer; vinyl butyral-based polymers; arylate polymers; polyoxymethylene polymer. In addition, a plastic film whose main component is a blend of these polymers can also be used.

  As described later, the hard coat film of the present invention can be used in the form of a hard coat laminate by laminating and bonding to various optical films such as a polarizer. Further, as the transparent film, for example, by using a polarizer, a hard coat polarizing plate (a hard coat film having a polarizing function) in which a hard coat layer is directly provided on the polarizer can be configured. Similarly, as the transparent film, for example, by using a phase difference plate, a hard coat phase difference plate (a hard coat film having an optical compensation function) in which a hard coat layer is directly provided on the phase difference plate can be configured. it can. Similarly, as the transparent film, for example, by using a protective film, a hard coat protective film (a hard coat film also serving as a protective film) in which a hard coat layer is directly provided on the protective film can be formed. . Such a hard coat protective film can constitute a hard coat polarizing plate by being laminated on one side or both sides of a polarizer. In this case, as the transparent film used for the hard coat protective film, it is preferable to use, for example, a film mainly composed of triacetyl cellulose, polycarbonate, acrylic polymer, olefin polymer having a cyclic or norbornene structure, and the like.

The thickness of the transparent film can be determined as appropriate, but is generally about 10 μm to 500 μm from the viewpoints of workability such as strength and handleability and thin layer properties. The thickness is preferably 20 μm to 300 μm, more preferably 30 μm to 200 μm.
The refractive index of the transparent film is not particularly limited, and is usually about 1.30 to 1.80, preferably 1.40 to 1.70.
Although the birefringence of a transparent film is not specifically limited, A small thing is preferable. For example, the in-plane retardation of the transparent film is determined by the in-plane main refractive index nx, ny (where nx> ny) and the film thickness d (Δnd = (nx−ny) × d). The in-plane retardation is desirably 100 nm or less, preferably 30 nm or less, more preferably 10 nm or less. This is because if the birefringence is large, the reflected light may appear iridescent due to interface reflection and interference of external light, which may reduce the display quality. However, the in-plane retardation is a value measured at 23 ° C. with an automatic birefringence meter (product name: KOBRA-21ADH) manufactured by Oji Scientific Instruments.
However, when a retardation plate is used as the transparent film, a film having an appropriate in-plane retardation and / or thickness direction retardation is used according to the application.

(About hard coat layer)
The hard coat layer is provided on one side or both sides of the transparent film.
As described above, the hard coat layer is arranged in such a manner that the upper surfaces of the plurality of plate-like glass particles are substantially parallel to the surface of the transparent film. The plate-like glass fine particles are fixed by a binder.
The thickness of the hard coat layer is not particularly limited and may vary depending on the plate-like glass fine particles used, but is usually about 5 μm to 30 μm, preferably about 8 μm to 20 μm, more preferably 10 μm to 18 μm. According to the present invention, a hard coat layer having a pencil hardness of 4H or more can be formed even when formed in a relatively thin layer as described above.

  FIG. 3 shows an example of plate-like glass fine particles (plate-like glass fine particles having a scaly top view). In the figure, 10 indicates plate-like glass particles, 11 indicates the upper surface of the plate-like glass particles 10, 12 indicates the lower surface of the plate-like glass particles 10, and 13 indicates the side surface of the plate-like glass particles 10. L represents the maximum length of the upper surface 11 of the plate-like glass fine particles 10, T represents the thickness of the plate-like glass fine particles 10, and W represents a plate in a direction orthogonal to the direction of the maximum length L. The width length of the upper surface 11 of the glassy glass fine particle 10 is shown.

In the present invention, the plate-like glass fine particles are fine particles obtained by forming glass into a plate shape. The plate-like glass fine particles are not particularly limited as long as they are glass fine particles having a shape in which the area of the upper surface is wider than the area of the side surface (thickness surface), and appropriate ones can be used. The plate-like glass particles preferably have an aspect ratio of 15 or more, and preferably have an aspect ratio of 20 or more. In addition, the upper limit of the aspect ratio of the plate-like glass fine particles is an aspect ratio of 40 or less, preferably an aspect ratio of 30 or less from the viewpoint of the shape stability of the plate-like glass fine particles. By using the plate-like glass fine particles having such an aspect ratio, the plate-like glass fine particles can be arranged in a substantially parallel manner on the transparent film. Therefore, the surface hardness of the hard coat layer can be increased, and curling of the film can be suppressed.
In addition, it is preferable that all the plate-like glass fine particles contained in the hard coat layer satisfy the above aspect ratio, but the total amount (mass) of the plate-like glass fine particles contained in the hard coat layer is used. On the other hand, 80% (mass ratio) or more of plate-like glass fine particles satisfying the above aspect ratio may be used.
However, the aspect ratio is obtained by [the maximum length L on the upper surface of the plate-like glass fine particles / the thickness T of the plate-like glass fine particles].

  Further, the maximum length L: width length W on the upper surface of the plate-like glass fine particles is preferably 5: 1 to 1: 1, more preferably 3: 1 to 1: 1. This is because if the shape of the upper surface of the plate-like glass particles is too long, the plate-like glass particles may not be oriented substantially in parallel.

The plate-like glass fine particles preferably have a flat upper surface, more preferably have a flat upper surface and a lower surface, and in particular, the upper and lower surfaces are parallel to each other. Some are more preferred.
The shape of the plate-like glass fine particles is not particularly limited, and is a scaly top view as shown in FIG. 3, and although not shown in the figure, a top view polygonal shape such as a top view rectangular shape or a triangular shape, a top view circular shape, a top view A view elliptical shape is exemplified.
A preferred specific form of the plate-like glass microparticles is a top view scaly shape or a top view circular shape (including an elliptical shape), and the maximum length of the top surface is about 10 μm to 50 μm, preferably the maximum length is 10 μm to The thickness is 30 μm, and the thickness is about 0.4 μm to 3.0 μm, preferably 0.4 μm to 2.0 μm.

As the plate-like glass fine particles, those having a surface subjected to silane coupling treatment are used. The silane coupling agent used for the silane coupling treatment is not particularly limited, and for example, a vinyl silane coupling agent, an amino silane coupling agent, an epoxy silane coupling agent, an acrylic silane coupling agent, and the like can be used. Particularly preferred is a vinyl silane coupling agent. The vinyl silane coupling agent has a vinyl group as a functional group, and examples thereof include vinyl triethoxy silane and vinyl trimethoxy silane.
By using the plate-like glass fine particles subjected to the silane coupling treatment, a hard coat layer having higher surface hardness can be formed. Although this effect is not clear, the hard coat in which the coupling agent coated on the surface of the plate-like glass fine particles is firmly adhered to the binder resin, and as a result, the plate-like glass fine particles aligned in parallel with the resin are integrated. It is estimated that a layer can be formed.

  As the binder for fixing the plate-like glass fine particles, a plate-like glass fine particle can be dispersed and fixed in parallel, and it has sufficient strength as a film after forming the hard coat layer, and can be used without particular limitation. Examples of the binder include a resin curable by heat or a resin curable by ionizing radiation. It is preferable to use an ionizing radiation curable resin from the viewpoints of high processing speed and resistance to thermal damage to the transparent film.

  As the resin that is cured by heat, known polymers such as acrylic, polycarbonate, and polystyrene can be used, which can be dissolved in a suitable solvent. The resin includes a resin that cures by volatilizing a solvent by heat.

  As the ionizing radiation curable resin, usually, an ultraviolet curable resin, an electron beam curable resin, or the like can be used. As the ionizing radiation curable resin, (meth) acryloyl group in the molecule ("(meth) acryloyl" means acryloyl or methacryloyl, and the following (meth) has the same meaning), (meth) Examples include prepolymers and oligomers having a polymerizable unsaturated bond group such as an acryloyloxy group or an epoxy group, and a composition in which monomers are appropriately mixed as necessary. Specific examples of these prepolymers and oligomers include acrylates such as urethane (meth) acrylate, polyester (meth) acrylate, and epoxy (meth) acrylate, silicon resins such as siloxane, unsaturated polyester, and epoxy. Specific examples of the monomer include styrene monomers such as styrene and α-methylstyrene, methyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta ( Examples include meth) acrylate, trimethylolpropane tri (meth) acrylate, and polyol compounds having two or more thiol groups in the molecule.

  A conventionally known photopolymerization initiator is added to the ionizing radiation curable resin. Examples of the photopolymerization initiator include 2,2-dimethoxy-2-phenylacetophenone, acetophenone, benzophenone, xanthone, 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, benzoinpropyl ether, benzyl Dimethyl ketal, N, N, N ′, N′-tetramethyl-4,4′-diaminobenzophenone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, other thioxanthates Examples thereof include compounds.

The hard coat layer is formed of a composition containing the binder and the plate-like glass fine particles, and various additives are blended in the composition as necessary within a range not impairing the effects of the present invention. May be.
Examples of the additive include a fluorine-based or silicone-based leveling agent, a filler, a dispersant, a plasticizer, an ultraviolet absorber, a surfactant, an antioxidant, and a thixotropic agent.

  The content of the plate-like glass fine particles in the hard coat layer is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, and particularly preferably 5 to 15% by mass. If the amount of the plate-like glass particles is too small, sufficient hardness and curl suppressing effect cannot be obtained.If the amount is too large, the amount of the binder is relatively reduced, so that the plate-like glass particles are peeled off, This is because the dispersibility of the plate-like glass fine particles is lowered in the (solution state).

The binder and the plate-like glass fine particles preferably have a refractive index as close as possible. Specifically, the binder and the plate-like glass fine particles preferably have a refractive index difference of less than 0.05. This is because, when the difference in refractive index is 0.05 or more, the scattering of light generated at the interface between the plate-like glass fine particles and the binder becomes too strong, and the image display may be blurred.
The difference in refractive index is obtained by the following formula: | refractive index of solidified binder-refractive index of sheet glass fine particles |.

<Use of hard coat film>
The hard coat film can be used in a portion where it is desired to prevent scratches. Typically, a hard coat film is suitable for applications such as a screen for an image display device such as a liquid crystal display device, a surface protection film such as a touch panel used for home appliances, and the like. When used for an image display device application, the hard coat film is attached to the screen of the image display device or an optical film incorporated in the screen. Moreover, a hard coat film is integrated in an image display apparatus in the form of a hard coat laminated body by laminating | stacking on various optical films.

Optical films for laminating hard coat films include polarizers, retardation plates, brightness enhancement films and laminates thereof; polarizing plates with protective films laminated on the polarizers; protective films and retardation plates laminated on the polarizers The elliptically polarizing plate etc. which were made are mentioned. A conventionally well-known thing can be used for a polarizer, a phase difference plate, a brightness enhancement film, a polarizing plate, etc.
The polarizer is preferably a hydrophilic polymer film dyed with a dichroic dye. Specifically, the polarizer is preferably a stretched polyvinyl alcohol film dyed with iodine or a dichroic dye. A polarizer comprising a hydrophilic polymer film dyed with such a dichroic dye usually swells the film, dyes the swollen film with a dichroic dye, and crosslinks the film with a crosslinking agent such as boric acid. And after performing each process which performs an extending | stretching process, it can obtain by drying.

  For example, the hard coat film and the optical film are formed using a known pressure-sensitive adhesive or adhesive as a base polymer such as an acrylic polymer, a silicone polymer, an ester polymer, a urethane polymer, an epoxy polymer, or a rubber polymer. Laminate adhesion is possible.

Examples of the image display device include a liquid crystal display device (LCD), a plasma display panel (PDP), an organic EL display (ELD), and a cathode ray tube television.
The image display device is used for arbitrary purposes. Applications include, for example, personal computer monitors, notebook computers, copiers and other OA devices, mobile phones, watches, digital cameras, personal digital assistants (PDAs), portable game machines and other portable devices, video cameras, televisions, microwave ovens, etc. Home appliances, back monitors, car navigation system monitors, in-vehicle devices such as car audio, display equipment such as information monitors for commercial stores, security equipment such as monitoring monitors, nursing monitors, medical use Care and medical equipment such as monitors.

<Method for producing hard coat layer>
In the hard coat film of the present invention, for example, a composition containing a plurality of plate-like glass fine particles and a binder is coated on a transparent film, and the plate-like glass fine particles are arranged substantially in parallel on the transparent film. In this state, it can be obtained by solidifying the binder and fixing the plate-like glass particles arranged in a substantially parallel shape.
An appropriate method such as die coating, casting, or spin coating can be used for coating the coating composition. Above all, by continuous coating, the plate-like glass fine particles can be oriented in parallel to the surface of the transparent film, so that coating using a coating die is simple and excellent in productivity. .
Hereinafter, a method for forming a hard coat layer by coating the coating composition on a transparent film using a coating die will be specifically described.

(About coating agent)
As the coating agent (coating composition), a composition in which plate-like glass fine particles are contained in a binder resin as described above can be used. Since the solution-form coating agent is prepared so as to have an appropriate fluidity, a dilution solvent may be mixed as necessary. The diluting solvent is not particularly limited. For example, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, acetone , Methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, ethyl acetate n- Pentyl, acetylacetone, diacetone alcohol, methyl acetoacetate, ethyl acetoacetate, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pen Nord, 2-methyl-2-butanol, cyclohexanol, isobutyl acetate, methyl isobutyl ketone, 2-octanone, 2-pentanone, 2-hexanone, 21-heptanone, 3-pentanone, 3-heptanone, 4-heptanone, etc. . These can be used alone or in combination of two or more.

The coating agent is prepared to have an appropriate viscosity so that the plate-like glass fine particles are oriented in one direction at the time of coating. The viscosity (25 ° C.) of the coating agent is preferably 1 to 700 MPa · s, more preferably 5 to 500 MPa · s. However, the viscosity refers to that measured with a rheometer RS-1 manufactured by Harke.
The blending amount of the plate-like glass fine particles in the coating agent is appropriately set in consideration of the amount of the plate-like glass fine particles contained in the hard coat layer to be formed. Usually, the blending amount of the plate-like glass fine particles (concentration of the plate-like glass fine particles in the coating agent) in the coating agent is preferably 0.5 to 50% by mass, more preferably 1 to 30% by mass.

(About coating process)
FIG. 4 shows an example of a die coater used for manufacturing the hard coat layer of the present invention. However, in FIG. 4, it should be noted that the relative sizes of the members such as the roll body, the rotating roller, the coating die, and the plate-like glass particles are different from the actual ones.
The die coater device 5 includes a coating die 6 for discharging a material and a rotating roller 7 for feeding a long transparent film 9 (raw film) in one direction (indicated by an arrow). The coating die 6 is arranged so that the discharge port 64 faces the rotation roller 7 so that the longitudinal direction of the discharge port 64 is parallel to the rotation axis direction of the rotation roller 7. Note that a large number of rotating rollers for feeding the transparent film 9 are usually provided, including a tension roller. However, in the drawing, only the roller disposed opposite to the coating die 6 with the transparent film 9 interposed therebetween is shown. . The rotating roller 7 is made of a rotatable cylindrical body that is wider than the width of the long transparent film.

The coating die 6 is opened at the first lip body 61, the second lip body 62, the shim 63 interposed between the both lip bodies 61, 62, and the tip portions of the both lip bodies 61, 62. It has a discharge port 64, a manifold portion 65 formed inside the die and communicating with the discharge port 64, and a supply path 66 communicating with the manifold portion 65.
The discharge port 64 is formed to be elongated in the width direction of the transparent film 9 (direction orthogonal to one direction). Further, the manifold portion 65 is configured to allow the coating agent to flow in the vertical direction with respect to the upper surface of the transparent film 9.
The long transparent film 9 can use the thing of the aspect of the roll body 91 wound up by roll shape, for example. The transparent film 9 is drawn out from the roll body 91, subjected to a coating process with a coating die, and then wound up again in a roll shape to form a re-roll body 92. Such a roll-up system from the roll is preferable because the hard coat layer can be continuously formed on the transparent film and is excellent in productivity.

In addition, 8 shows the solidification zone for hardening resin, and an appropriate thing is provided according to the hardening characteristic of the binder (resin component) contained in a coating agent. The solidification zone 8 is provided with, for example, an ionizing radiation irradiation device such as ultraviolet rays, a solvent recovery device, a heating device, etc. according to the curing characteristics of the resin.
Reference numeral 10 denotes plate-like glass fine particles dispersed in the coating agent. 4 shows the binder (light ink coating) of a coating agent.

A procedure for producing a hard coat layer using the die coater will be described with reference to FIG.
First, a transparent film roll body 91 is loaded on the upstream side of the die coater 5.
Various processes may be performed on the transparent film 9 before the hard coat layer 3 is formed. For example, when a hard coat layer is directly formed on a polarizer dyed with a dichroic dye, a PVA-based unstretched film wound in a roll is loaded on the upstream side, and a known polarization treatment ( After the film is swollen, dyed, crosslinked, stretched, stretched, washed, dried, etc., the hard coat layer 3 may be formed on the upper surface of the film using the die coater device 5.

The transparent film 9 loaded on the upstream side of the die coater device 5 is drawn out from the roll body 91 and is sent in one direction at any time. The coating agent is discharged from the discharge port 64 of the coating die 6 onto the upper surface of the transparent film 9 that is sent. In the coating die 6, the coating agent is supplied from the supply path 66 and flows out from the discharge port 64 through the manifold portion 65.
Due to the thin plate-like shape of the plurality of plate-like glass particles 10 contained in the coating agent, the upper surface of the plate-like glass particles 10 is transparent while flowing together with the binder in the manifold portion 65. The film 9 is oriented in a direction perpendicular to one direction (feeding direction) of the film 9. Accordingly, the plate-like glass fine particles 10 are discharged from the discharge port 64 to the upper surface of the transparent film 9 with the upper surface orthogonal to the upper surface of the transparent film.
And since the transparent film 9 is sent out to one direction, a shearing force acts in a coating agent by the movement of the transparent film 9. FIG. As a result, as shown in the drawing, the plate-like glass fine particles 10 discharged perpendicularly to the transparent film 9 are tilted so that the upper side of the plate-like glass fine particles 10 is opposite to the sending direction of the transparent film 9, and further transparent. As the film 9 is delivered, the plate-like glass fine particles 10 are oriented substantially parallel to the upper surface of the transparent film 9.

After coating, the plate-like glass fine particles 10 are fixed in a state of being arranged substantially in parallel by curing the binder of the coating agent in the solidification zone 8. When the binder is an ionizing radiation curable resin, the ionizing radiation irradiating device in the solidification zone 8 is a radiation source such as a high pressure mercury lamp, a halogen lamp, a xenon lamp, a nitrogen laser, an electron beam accelerator, or a radioactive element. Is used. The irradiation amount of the energy ray source is appropriately set according to the type of the resin component and the photopolymerization initiator. For example, the integrated exposure amount at an ultraviolet wavelength of 365 nm is exemplified by about 50 to 5,000 mJ / cm ^2. Is done.

In this way, the hard coat layer 3 including the plate-like glass fine particles 10 is formed on the upper surface of the transparent film 9. After that, the transparent film 9 on which the hard coat layer 3 is formed is wound up again in a roll shape.
According to the method for producing a hard coat layer, the plate-like glass particles 10 are made substantially parallel by simply applying a coating agent containing the plate-like glass particles 10 to the transparent film 9 sent in one direction. The hard coat layer can be formed by fixing. Therefore, it is possible to easily form a hard coat layer on an appropriate transparent film using existing equipment including a coating die.

Examples of the present invention and comparative examples will be described below. However, the present invention is not limited to the following examples.
“Part” and “%” are based on mass unless otherwise specified.

[Materials Used in Examples and Comparative Examples]
(A) UV curable resin A: manufactured by Dainippon Ink & Chemicals, Inc., trade name: GRANDIC PC4 4145.
(B) Plate-like glass microparticles B subjected to vinylsilane coupling treatment: Nippon Sheet Glass Co., Ltd., trade name: MTG025FXY6013. Aspect ratio of 20. Top view is generally scaly and has a diameter of 25 μm.
(C) Plate-like glass fine particles C not subjected to vinylsilane coupling treatment: manufactured by Nippon Sheet Glass Co., Ltd., trade name: MTG025FXY6003. Aspect ratio of 20. Top view is generally scaly and has a diameter of 25 μm.
(D) Mica fine particles D: manufactured by Nippon Koken Kogyo Co., Ltd., trade name: MF-90. Aspect ratio of 20. Top view is generally scaly and 4 μm in diameter.
(E) Transparent film E: a triacetyl cellulose film having a thickness of 40 μm (refractive index: 1.48).
However, the method for determining the aspect ratio is as follows. Taking a scanning electron microscope (SEM) photograph of the fine particles, measuring the longest diameter of the fine particles and the maximum length in the direction (thickness) perpendicular to the longest diameter, the formula: [longest diameter of fine particles / thickness of fine particles The aspect ratio was determined by substituting for [maximum length]. This was performed for 10 samples, and the average value was taken as the aspect ratio.

[Example 1]
The ultraviolet curable resin A is diluted with a mixed solvent of butyl acetate and ethyl acetate so that the solid content concentration becomes 50%, and the plate-like glass fine particles B treated with vinyl silane coupling are diluted with the resin solid content. 10 parts were added to 100 parts and stirred to prepare a coating agent for forming a hard coat. This coating agent was applied onto the transparent film E using a bar coater. Next, this coating film is dried by heating at 100 ° C. for 1 minute, and then irradiated with ultraviolet rays having an integrated light quantity of 300 mJ / cm ^{2 with} a metal halide lamp to cure the resin component, thereby forming a 10 μm thick hard A coat layer was formed.
When the cross section of the obtained hard coat layer was observed with a scanning electron microscope (SEM), it was confirmed that the plate-like glass fine particles were aligned in parallel to the surface of the transparent film E. Hereinafter, when the hard coat layers of Examples 2 to 4 and Comparative Examples 1 to 4 were also observed in the same manner, each fine particle was aligned in parallel with the surface of the transparent film E.

[Example 2]
A hard coat layer having a thickness of 12 μm was formed in the same manner as in Example 1 except that the coating thickness of the coating agent was changed.

[Example 3]
A hard coat layer having a thickness of 14 μm was formed in the same manner as in Example 1 except that the number of added parts of the plate-like glass fine particles B was changed to 5 parts and the coating thickness of the coating agent was changed.

[Example 4]
A hard coat layer having a thickness of 14 μm was formed in the same manner as in Example 1 except that the coating thickness of the coating agent was changed.

[Example 5]
A hard coat layer having a thickness of 16 μm was formed in the same manner as in Example 1 except that the coating thickness of the coating agent was changed.

[Comparative Example 1]
A hard coat layer having a thickness of 10 μm was formed in the same manner as in Example 1 except that the plate-like glass fine particles B were not added.

[Comparative Example 2]
A hard coat layer having a thickness of 10 μm was formed in the same manner as in Example 1 except that the plate-like glass fine particles C not subjected to the vinyl silane coupling treatment were used instead of the plate-like glass fine particles B subjected to the vinyl silane coupling treatment. Formed.

[Comparative Example 3]
A hard coat layer having a thickness of 16 μm was formed in the same manner as in Comparative Example 2 except that the coating thickness of the coating agent was changed.

[Comparative Example 4]
A hard coat layer having a thickness of 16 μm was formed in the same manner as in Example 5 except that the plate-like glass fine particles B were changed to mica fine particles D.

  The thickness of the hard coat layer in each of the above Examples and Comparative Examples was measured using a Mitutoyo micro gauge thickness meter. Specifically, the thickness of the hard coat layer was calculated by measuring the thickness of the hard coat film provided with the hard coat layer on the transparent film and subtracting the thickness of the transparent film from this thickness.

[Surface hardness test]
Each hard coat film obtained in each of the above Examples and Comparative Examples was pasted with a pressure-sensitive adhesive on a glass plate via a pressure-sensitive adhesive having a thickness of about 20 μm, and in accordance with the pencil hardness test of JIS K 5400 ( However, the load was 500 g) and the pencil hardness was measured. The results are shown in Table 1.

[Curl test]
Each hard coat film obtained in each of the above Examples and Comparative Examples was cut out to 100 mm × 100 mm, the diameter of the cylindrical film was measured, and this diameter was taken as the curl value. The results are also shown in Table 1.

[Evaluation]
The hard coat layers of Examples 1 to 4 have a pencil hardness of “4H” and can suppress the occurrence of curling. On the other hand, the hard coat layers of Comparative Examples 2 and 3 have low pencil hardness. It can be said that the plate-like glass particles used in Examples 1 to 4 improve the surface hardness of the hard coat layer due to the material. Moreover, although the improvement of surface hardness is recognized when the mica microparticles | fine-particles of the same shape as the plate-like glass microparticles of Examples 1 to 4 are added as in Comparative Example 4, the effect of Examples 1 to Compared with the case where the plate-like glass fine particles 4 are used, it is not remarkable.

(A) is a reference perspective view which shows one Embodiment of the hard coat film of this invention, (b) is a reference perspective view which shows other embodiment of the hard coat film. The principal part cross-sectional enlarged view cut | disconnected by the II line | wire of Fig.1 (a). (A) is a front view which shows an example of plate-like glass microparticles, (b) is the side view. The reference side view which shows the manufacturing process of a hard-coat layer. However, the middle part of the transparent film is omitted, and the coating die is shown in a sectional view.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Hard coat film, 2 ... Transparent film, 21 ... Surface of transparent film, 3 ... Hard coat layer, 4 ... Binder, 6 ... Coating die, 9 ... Elongate transparent film, 10 ... Plate-like glass microparticle, DESCRIPTION OF SYMBOLS 11 ... Upper surface of plate-like glass particle, 12 ... Lower surface of plate-like glass particle, 13 ... Side surface of plate-like glass particle

Claims (9)

At least one surface of the transparent film is provided with a hard coat layer mainly composed of a resin that is cured by heat or ionizing radiation,
The hard coat layer includes plate-like glass fine particles subjected to silane coupling treatment, and the plate-like glass fine particles are expressed by [maximum length on the upper surface of the plate-like glass fine particles / thickness of the plate-like glass fine particles]. A hard coat film , wherein the required aspect ratio is 15 or more, and the plate-like glass fine particles are oriented substantially parallel to the surface of the transparent film.   The hard coat film according to claim 1, wherein the coupling agent used in the silane coupling treatment includes a vinyl silane coupling agent.   The hard coat film according to claim 1, wherein the hard coat layer has a thickness of 8 to 20 μm.   The hard coat film according to any one of claims 1 to 3, wherein the plate-like glass fine particles have a thickness of 0.4 µm to 3.0 µm and a maximum length of 10 µm to 50 µm.   The hard coat film according to claim 1, wherein the hard coat layer has a pencil hardness of 4H or more.   The hard coat film according to claim 1, wherein the transparent film is a polarizer or a protective film laminated on the polarizer.   The hard coat film laminated body by which the hard coat film in any one of Claims 1-6 is laminated | stacked on the at least single side | surface of the optical film.   The hard coat film laminate according to claim 7, wherein the optical film is a polarizer or a polarizing plate.   An image display device comprising the hard coat film according to claim 1 or the hard coat film laminate according to claim 7 or 8.

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