阅读说明：本技术 硬质涂膜、使用该硬质涂膜的偏光板、硬质涂膜加工品、显示部件 (Hard coating film, polarizing plate using same, hard coating film processed product, and display member ) 是由 新纳干大 松井佑纪男 于 2017-02-14 设计创作，主要内容包括：提供兼具高硬度、低卷曲性、高弯曲性的硬质涂膜、使用该硬质涂膜的偏光板、硬质涂膜加工品和显示部件。一种硬质涂膜,其是在透明基材(2)的两面上设置有硬质涂层(3a和3b)的硬质涂膜(1),其特征在于,透明基材(2)的厚度为5μm以上40μm以下,硬质涂层(3a和3b)各自的厚度均为5μm以上30μm以下,硬质涂层(3a和3b)的体积的合计为硬质涂膜(1)的总体积的40％以上,并且,硬质涂膜(1)的总厚度为80μm以下。(Provided are a hard coating film having high hardness, low curling properties, and high bendability, and a polarizing plate, a hard coating film-processed product, and a display member using the hard coating film. A hard coat film (1) having hard coat layers (3a and 3b) provided on both surfaces of a transparent base material (2), characterized in that the thickness of the transparent base material (2) is 5 [ mu ] m or more and 40 [ mu ] m or less, the thickness of each of the hard coat layers (3a and 3b) is 5 [ mu ] m or more and 30 [ mu ] m or less, the sum of the volumes of the hard coat layers (3a and 3b) is 40% or more of the total volume of the hard coat film (1), and the total thickness of the hard coat film (1) is 80 [ mu ] m or less.)

1. A hard coat film comprising a transparent base material and hard coat layers provided on both surfaces of the transparent base material,

the thickness of the transparent base material is 5-40 μm,

the hard coat layers each have a thickness of 5 to 30 [ mu ] m,

the sum of the volumes of the hard coat layers is 40% or more of the total volume of the hard coat film, and,

the total thickness of the hard coating film is 80 mu m or less,

the hardness of the pencil is more than 7H,

the hardness of the ultramicro indentation at a position 50nm deep from the surface is 450N/mm²In the above-mentioned manner,

the height of standing 4-angle film of a sample obtained by cutting the hard coating film into 100mm square pieces is 20mm or less,

the minimum diameter of the hard coat layer is 8mm or less when no crack is generated.

2. The hard coating film according to claim 1,

the hard coat layer on one surface of the transparent base material contains colloidal silica and an ultraviolet curable resin,

the hard coat layer on the other surface of the transparent base material contains an ultraviolet curable resin.

3. The hard coating film according to claim 2,

the colloidal silica has an average particle diameter of 80nm or less,

the hard coat layer on the one surface of the transparent substrate contains 20 to 70 mass% of the colloidal silica,

the colloidal silica is surface-treated colloidal silica having an ultraviolet reactive group on the surface.

4. The hard coating film according to claim 2,

the transparent substrate is a film of any one of cellulose triacetate, cyclic olefin polymer, cyclic olefin copolymer, acrylic, polyethylene terephthalate, polyimide, and polycarbonate.

5. A polarizing plate comprising the hard coat film according to claim 1.

6. The polarizing plate according to claim 5,

the hardness of the pencil is more than 7H,

the hardness of the ultramicro indentation at a position 50nm deep from the surface is 450N/mm²In the above-mentioned manner,

the height of the film standing at 4 corners of a sample obtained by cutting the polarizing plate into 100mm square pieces is 20mm or less,

the minimum diameter of the hard coat layer is 8mm or less when no crack is generated.

7. A display member having the polarizing plate according to claim 5.

8. A hard coat film-processed product obtained by providing an adhesive layer on one surface of the hard coat film according to claim 1.

9. A hard coat film processed product obtained by providing a print layer and an adhesive layer on one surface of the hard coat film according to claim 1.

10. The hard coating processed product according to claim 8 or 9,

the hardness of the pencil is more than 7H,

the hardness of the ultramicro indentation at a position 50nm deep from the surface is 450N/mm²In the above-mentioned manner,

the height of the 4-angle film standing of the sample obtained by cutting the hard coating film processed product into 100mm square is less than 20mm,

the minimum diameter of the hard coat layer is 8mm or less when no crack is generated.

11. A display member comprising the hard coat film-processed product according to claim 8 or 9.

Technical Field

The present invention relates to a hard coating film for a display device, and a polarizing plate, a hard coating film processed product, and a display member using the hard coating film.

Background

In display members such as liquid crystal display panels and touch panels, hard coating films are used to improve surface hardness and scratch resistance. The hard coat film is obtained by forming a hard coat layer composed of a cured film of a resin composition on the surface of a transparent substrate. With the recent reduction in thickness and weight of display devices, the hard coating film is also required to be reduced in thickness, and the transparent substrate used for the hard coating film is also required to be reduced in thickness.

For example, patent document 1 describes: a curable resin composition for a hard coat layer, which contains reactive silica fine particles having a reactive functional group on the surface, a polyfunctional monomer having 3 or more reactive functional groups in 1 molecule, and a reactive polymer having a specific molecular structure, is applied to one surface of a substrate and cured, thereby forming a hard coat layer having high hardness while forming a thin film.

Documents of the prior art

Patent document

Patent document 1 Japanese patent application laid-open No. 2010-120991

Disclosure of Invention

Problems to be solved by the invention

In a configuration in which a hard coat layer is provided only on one surface of a substrate, such as the hard coat film described in patent document 1, it is sometimes necessary to increase the thickness of the curable resin composition for a hard coat layer in order to obtain a desired hardness. In this case, there are the following problems: the curl of the obtained hard coat film is too strong, and the use convenience is poor when the hard coat film is further processed or used as a display member. In addition, when a hard coat layer is provided on one surface of a thin substrate having a thickness of 40 μm or less, the pencil hardness of the hard coat film is likely to be deteriorated due to the influence of the substrate having a low hardness. In addition, a hard coating film having a hard coating layer provided on one surface thereof has a problem that the flexibility is weakened and the hard coating layer is easily broken.

Accordingly, an object of the present invention is to provide a hard coating film having high hardness, low curling properties, and high bendability, and a polarizing plate, a hard coating film-processed product, and a display member using the hard coating film.

Means for solving the problems

The present invention relates to a hard coat film having hard coatings provided on both surfaces of a transparent substrate. The hard coat film according to the present invention is characterized in that the thickness of the transparent base material is 5 μm or more and 40 μm or less, the thickness of each hard coat layer is 5 μm or more and 30 μm or less, the total volume of the hard coat layers is 40% or more of the total volume of the hard coat film, and the total thickness is 80 μm or less.

The polarizing plate, the hard coating processed product and the display member according to the present invention have the hard coating.

Effects of the invention

According to the present invention, a hard coat film having high hardness, low curling properties, and high bendability, and a polarizing plate, a hard coat processed product, and a display member using the hard coat film can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view of a hard coat film according to an embodiment.

Fig. 2 is a schematic view showing a test method of a bending test (cylindrical winding test method).

Detailed Description

Fig. 1 is a schematic cross-sectional view of a hard coat film according to an embodiment.

The hard coat film 1 is provided with hard coat layers 3a and 3b on both surfaces of a transparent base material 2.

(transparent substrate)

The transparent substrate 2 is a film that is a base of the hard coating film 1. The transparent substrate 2 is not particularly limited as long as it is a film made of a material having excellent transparency and visible light transmittance, and for example, a film made of any one of cellulose triacetate, cycloolefin polymer, cycloolefin copolymer, acrylic polymer, polyethylene terephthalate, polyimide, and polycarbonate can be used.

The thickness of the transparent substrate 2 is 5 to 40 μm. If the thickness of the transparent base material 2 is less than 5 μm, the transparent base material 2 becomes too thin, and the hardness of the hard coat layer 3 and the strength of the hard coat film 1 decrease. On the other hand, if the thickness of the transparent substrate 2 exceeds 40 μm, the hard coating film 1 becomes thick, and thus it does not contribute to the thinning of the display member using the hard coating film 1.

(hard coating)

The hard coat layers 3a and 3b are formed by curing a hard coat layer-forming composition containing at least an active energy ray-curable resin such as ultraviolet rays or electron beams as a binder resin. At least one of the hard coat layers 3a and 3b is formed by curing a hard coat layer-forming composition containing an active energy ray-curable resin and colloidal silica. If colloidal silica is contained in at least one of the hard coat layers 3a and 3b, the pencil hardness of the hard coat film 1 can be 7H or more. Both the hard coat layers 3a and 3b may be formed of an active energy ray-curable resin containing colloidal silica.

The thickness of the hard coatings 3a and 3b is 5 to 30 μm. If the thickness of the hard coatings 3a and 3b is less than 5 μm, the hardness of the hard coatings 3a and 3b is insufficient. On the other hand, if the thickness of the hard coat layers 3a and 3b exceeds 30 μm, the thickness of the hard coat film 1 becomes large, and therefore, it does not contribute to the thinning of the display member using the hard coat film 1.

The colloidal silica is a component that imparts hardness to the hard coat layer 3 a. As the colloidal silica, colloidal silica having an average particle diameter of 80nm or less is used. If the average particle diameter of the colloidal silica exceeds 80nm, the transparency of the hard coating film is lowered. The lower limit of the average particle size of the colloidal silica is not particularly limited, and colloidal silica having an average particle size of 5nm or more can be suitably used.

The amount of colloidal silica added is set to 20 to 70 mass% of the total solid content contained in the composition for forming a hard coat layer. If the amount of the colloidal silica added is less than 20 mass% of the resin solid content, the hardness of the hard coat layer 3a becomes insufficient. On the other hand, if the amount of colloidal silica added exceeds 70 mass% of the resin solid content, the hard coating becomes brittle, resulting in a decrease in hardness.

As the colloidal silica, surface-modified colloidal silica surface-modified with active energy ray-reactive groups that are reactive by irradiation with active energy rays is preferably used. Such surface-modified colloidal silica can increase the hardness of the hard coat layer by crosslinking with an active energy ray-curable resin used as a binder.

The active energy ray-curable resin is a resin that is polymerized and cured by irradiation with active energy rays such as ultraviolet rays and electron beams, and a monofunctional, 2-functional, or 3-functional or higher (meth) acrylate monomer, for example, can be used. In the present specification, "(meth) acrylate" is a general term for both acrylate and methacrylate, and "(meth) acryloyl" is a general term for both acryloyl and methacryloyl.

Examples of the monofunctional (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, N-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, glycidyl (meth) acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, benzyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, hydroxyethyl (meth) acrylate, N-butyl (meth) acrylate, N-ethylhexyl (meth) acrylate, isobutyl (meth) acrylate, N-butyl (meth) acrylate, N-ethylhexyl (meth) acrylate, N-butyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, N-butyl (meth) acrylate, N-vinylpyrrolidone, N-hydroxyethyl (meth) acrylate, N-butyl (meth) acrylate, 2-acrylate, N-butyl (meth) acrylate, N-acrylate, 2-butyl (meth) acrylate, N-acrylate, 2-hydroxyethyl (meth) acrylate, 2-acrylate, N-acrylate, 2-hydroxyethyl (meth) acrylate, 2-butyl (meth) acrylate, 2-acrylate, N-acrylate, 2-acrylate, N-acrylate, and (meth) acrylate, 2-acrylate, N-acrylate, 2-acrylate, N-acrylate, 2-acrylate, and/2-acrylate, and the like, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phosphoric acid (meth) acrylate, ethylene oxide-modified phosphoric acid (meth) acrylate, phenoxy (meth) acrylate, ethylene oxide-modified phenoxy (meth) acrylate, propylene oxide-modified phenoxy (meth) acrylate, nonylphenol (meth) acrylate, ethylene oxide-modified nonylphenol (meth) acrylate, propylene oxide-modified nonylphenol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, methyl methacrylate, ethyl methacrylate, methyl methacrylate, ethyl methacrylate, methyl methacrylate, ethyl methacrylate, and ethyl methacrylate, Adamantane derivative mono (meth) acrylates such as 2- (meth) acryloyloxyethylphthalate, 2- (meth) acryloyloxypropyl hydrogenphthalate, 2- (meth) acryloyloxypropyl hexahydrophthalic acid hydrogenphthalate, 2- (meth) acryloyloxypropyl tetrahydrophthalic acid hydrogenphthalate, dimethylaminoethyl (meth) acrylate, trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, adamantyl acrylate having a monovalent mono (meth) acrylate derived from 2-adamantane or adamantanediol, and the like.

Examples of the 2-functional (meth) acrylate compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, nonanediol di (meth) acrylate, ethoxylated hexanediol di (meth) acrylate, propoxylated hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, and di (meth) acrylates such as polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, and hydroxypivalic acid neopentyl glycol di (meth) acrylate.

Examples of the 3-or more-functional (meth) acrylate compound include tri (meth) acrylates such as trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, tris 2-hydroxyethyl isocyanurate tri (meth) acrylate and glycerin tri (meth) acrylate, 3-functional (meth) acrylate compounds such as pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate and ditrimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta (meth) acrylate, glycerol tri (meth) acrylate, and the like, And polyfunctional (meth) acrylate compounds having 3 or more functions such as dipentaerythritol hexa (meth) acrylate and ditrimethylolpropane hexa (meth) acrylate, and polyfunctional (meth) acrylate compounds obtained by substituting a part of these (meth) acrylates with an alkyl group or epsilon-caprolactone.

As the active energy ray-curable resin, urethane (meth) acrylate may be used. Examples of the urethane (meth) acrylate include those obtained by reacting a product obtained by reacting a polyester polyol with an isocyanate monomer or a prepolymer with a (meth) acrylate monomer having a hydroxyl group.

Examples of the urethane (meth) acrylate include pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate isophorone diisocyanate urethane prepolymer, and dipentaerythritol pentaacrylate isophorone diisocyanate urethane prepolymer.

One kind of the active energy ray-curable resin may be used, or two or more kinds may be used in combination. The active energy ray-curable resin may be a monomer or an oligomer partially polymerized in the composition for forming a hard coat layer.

In the active energy ray-curable resin, it is preferable that the reactive polymer having a weight average molecular weight of 8000 to 15000 is contained in a proportion of 10 to 40 mass% of the solid content of the active energy ray-curable resin. By incorporating the reactive polymer as a part of the active energy ray-curable resin, curling of the hard coat film can be suppressed.

As the reactive polymer having a weight average molecular weight of 8000 to 15000, a polymer compound having a plurality of (meth) acryl groups or (meth) acryloyl groups bonded to the main chain can be used. Examples of the polymer compound include BEAMSET371, BEAMSET371MLV, BEAMSETDK1, BEAMSETDK2, BEAMSETDK3 (manufactured by "KANGCHUAN CHEMICAL WORKS "), SMP220A, and SMP-250A, SMP-360A, SMP-550A (manufactured by "CORPORATION CHEMICAL CO"). The reactive macromolecules have a double bond equivalent weight of 200 to 600 g/mol.

A photopolymerization initiator may be added to the composition for forming a hard coat layer. Examples of the photopolymerization initiator include 2, 2-ethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, dibenzoyl, benzoin methyl ether, benzoin ethyl ether, p-chlorobenzophenone, p-methoxybenzophenone, miller ketone, acetophenone, and 2-chlorothioxanthone. These may be used alone or in combination of two or more.

In addition, an appropriate solvent may be added to the composition for forming a hard coat layer. Examples of the solvent include ethers such as dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1, 4-dioxane, 1, 3-dioxolane, 1,3, 5-trioxane, tetrahydrofuran, anisole, and phenetole; ketones such as acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methylcyclohexanone; and esters such as ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate, and γ -butyrolactone; and cellosolves such as methyl cellosolve, butyl cellosolve, cellosolve acetate, and the like. These may be used alone or in combination of two or more.

As other additives, an antifouling agent, a surface modifier, a leveling agent, a refractive index modifier, a photosensitizer, and a conductive material may be added to the composition for forming a hard coat layer.

The hard coating film 1 according to the present embodiment can be formed by the following method: the coating liquid of the composition for forming a hard coat layer is applied to both surfaces of the transparent substrate by a wet coating method in a roll-to-roll manner, and the active energy ray-curable resin is cured by irradiating the coating film with an active energy ray such as an electron beam or ultraviolet ray. As the wet coating method, known methods such as a flow coating method, a spray coating method, a roll coating method, a gravure roll coating method, an air knife coating method, a blade coating method, a wire blade coating method, a knife coating method, a reverse coating method, a transfer roll coating method, a microgravure coating method, a contact coating method, a flow coating method, a slit die coating method, a calender coating method, and a die coating method can be used. In the case of curing the coating film by ultraviolet irradiation, when ultraviolet irradiation is employed, a high-pressure mercury lamp, a halogen lamp, a xenon lamp, a FUSION lamp, or the like can be used. The ultraviolet ray irradiation amount is usually 100 to 800mJ/cm²Left and right.

In the hard coat film 1 according to the present embodiment, a layer is formed by providing hard coat layers 3a and 3b on both surfaces of a transparent base 2, the thickness of the transparent base 2 is 5 to 40 μm, the thickness of each of the hard coat layers 3a and 3b is 5 to 30 μm, the total volume of the hard coat layers 3a and 3b is 40% or more of the total volume of the hard coat film 1, and the total thickness of the hard coat film 1 is 80 μm or less. In general, when a thin transparent substrate 2 having a thickness of 40 μm or less is used, the transparent substrate is made ofThe pencil hardness becomes worse under the influence of the transparent base material 2 having a low hardness. In contrast, in the present embodiment, the hard coat layers 3a and 3b are laminated on both surfaces of the transparent base material 2, and the volume ratio occupied by the transparent base material 2 is reduced, whereby the influence of the transparent base material 2 having low hardness can be reduced, and the hardness of the hard coat film 1 can be improved. Specifically, the following excellent hardness characteristics were exhibited: the surface of the hard coating film 1 has a pencil hardness of 7H or more, and a hardness of 450N/mm at an ultra-fine indentation at a depth of 50nm from the surface²The above.

In addition, by providing the hard coatings 3a and 3b on both surfaces of the transparent base material 2, curling (lifting) of the hard coating film 1 is suppressed, and resistance to bending is also improved. Specifically, the hard coat film 1 according to the present embodiment is cut into 100mm square pieces to prepare samples, and when the samples are placed on a plane, the heights of the four corners of the film standing up are 20mm or less. When the hard coating film 1 according to the present embodiment is bent, cracks are not generated in any of the hard coating layers 3a and 3b when the bending diameter of the bent portion is 10mm or more. As described above, the hard coating film 1 according to the present embodiment has an ultra-high hardness (pencil hardness of 7H or more), suppresses curling, and is excellent in bendability.

As described above, according to the present embodiment, the hard coat layers 3a and 3b are laminated on both surfaces of the transparent base material 2 in the thickness described above, whereby the hard coat film 1 having all of high hardness, low curling property, and high bendability can be realized.

(other modification example)

Note that, a hard coating processed product may be produced by performing edge (bezel) printing or providing an adhesive layer on any one of the hard coatings of the hard coating 1 according to the present embodiment. The hard coating film processed product may be provided with both edge-covering printing and an adhesive layer, or may be provided with edge-covering printing or an adhesive layer separately.

In addition, the hard coating film 1 according to the present embodiment or the hard coating film processed product described above may be used to form a polarizing plate. Specifically, a polarizing film is laminated on any one of the hard coat layers of the hard coat film 1 shown in fig. 1, whereby a polarizing plate can be formed. The polarizing film is obtained by, for example, adsorbing and orienting iodine or a dye on a polyvinyl alcohol film.

The hard coat film 1 according to the present embodiment or the hard coat film processed product can be used to constitute a display member such as an antireflection film or an antiglare film used in an image display device. An antireflection film can be formed by providing an antireflection layer formed by laminating a plurality of layers having different refractive indices on the hard coat layer 3a or 3b shown in fig. 1. The antireflection film is a film that: the light transmitted through the antireflection layer and reflected on the surface of the transparent substrate and the light reflected on the surface of the antireflection layer are canceled by interference, and reflection is suppressed. An example of the antireflection film is a film obtained by laminating a hard coat layer, a high refractive index layer, and a low refractive index layer having a lower refractive index than the high refractive index layer in this order on the transparent substrate 2. An intermediate refractive index layer having a lower refractive index than the high refractive index layer and a higher refractive index than the low refractive index layer may be further provided between the hard coat layer and the high refractive index layer. The antiglare film is a film: the fine irregularities formed on the surface scatter external light, thereby reducing reflection of external light and preventing glare. The antiglare film can be produced, for example, by: fine particles such as resin particles (organic filler) are added to the hard coat layer 3a or 3b, thereby forming fine irregularities on the surface.

Further, a layer having an antireflection function or an antiglare function may be combined with the polarizing plate. Specifically, a polarizing film is laminated on one of the hard coats 3a and 3b, and an antireflection layer is provided on the other, whereby a polarizing plate having an antireflection function can be configured. Alternatively, a polarizing film is laminated on one of the hard coats 3a and 3b, and resin particles are added to the other, whereby a polarizing plate having an antiglare function can be formed.

The hard coat film 1 according to the present embodiment or the hard coat film processed product can be used in combination with a liquid crystal panel or the like to form a display device. Examples of the display device include a device in which the hard coat film 1 according to the present embodiment or the antireflection film, the polarizing plate, the liquid crystal panel, the polarizing plate, and the backlight unit using the hard coat film processed product are stacked in this order from the observation side. Further, a touch sensor may be further stacked to form a display device with a touch sensor.

The hard coat film 1 according to the present embodiment or the hard coat film processed product can be used as an optical functional film used in a display device such as a smartphone, a tablet computer, or a notebook computer, or a display device with a touch sensor (touch panel). Examples of the optical functional film include the above-mentioned polarizing film, antireflection film, and antiglare film in addition to the hard coat film. Specifically, the hard coat film according to the present embodiment can be used as a film provided on the outermost surface of a display panel of a liquid crystal display device or the like, a film provided on the outermost surface of a touch panel, or an intermediate film provided between a touch sensor and a display panel in a touch panel assembled by a direct bonding method or an air gap method.

The polarizing plate, the hard coating processed product and the display member all have the hard coating 1 according to the invention, and have a pencil hardness of 7H or more on the surface and an ultramicro indentation hardness of 450N/mm at a depth of 50nm from the surface²The above excellent hardness characteristics. The polarizing plate, the hard coating processed product, and the display member were cut into a square of 100mm square to prepare a sample, and when the sample was placed on a flat surface, the height of the film standing at the four corners was 20mm or less. When the polarizing plate, the hard coat processed product, or the display member is bent, if the bending diameter of the bent portion is 10mm or more, neither of the hard coats 3a and 3b is cracked.

Examples

Hereinafter, examples embodying the present invention will be described.

A hard coat layer-forming composition having the following composition was applied to the surface of a transparent substrate made of Triacetylcellulose (TAC) by a bar coating method and dried, and then irradiated with 200m of radiation using a metal halide lampJ/m²The coating film was cured by ultraviolet irradiation to obtain a hard coating film.

< composition for forming hard coat layer >

Resin Material

PE-3A (pentaerythritol triacrylate), Kyoeisha chemical … 9 parts by mass

UA-306H (pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer), Kyoeisha chemical … 13 parts by mass

UB/EB curable resin BEAMSET371, available from Tokawa chemical K.K. … 7 parts by mass

Colloidal silica: MEK-ST (average particle size 15nm), Nissan chemical K … 43 parts by mass

Polymerization initiator: irgacure184 (1-hydroxycyclohexylphenylketone), BASF … 2 parts by mass

Solvent: … 26 parts by mass of methyl isobutyl ketone

Table 1 shows the thickness of the transparent substrate, the thickness of the hard coat layer, the total thickness of the hard coat film, and the volume ratio of the hard coat layer of the hard coat films according to examples 1 to 9 and comparative examples 1 to 6. In comparative examples 1, 2, 5 and 6, the hard coat layer was formed on only one surface of the transparent base material, and in other examples, the hard coat layers were formed on both surfaces of the transparent base material.

[ Table 1]

Table 1 also shows the evaluation results of the pencil hardness, the fine hardness, the curl, and the bending test of the hard coating films according to examples 1 to 9 and comparative examples 1 to 6. The measurement and evaluation methods of pencil hardness, micro hardness, curl and bending test shown in table 1 are as follows.

[ Pencil hardness ]

The pencil hardness of the hard coat surface was measured according to JIS K5400-1900 using a pencil (uni, Mitsubishi Pencil Co., Ltd.) and a Clemens type scratch tester (HA-301, テスター made by K.K.). The test was repeated while changing the hardness of the pencil, and the change in appearance due to the scratch was visually observed, and the maximum hardness at which the scratch was not observed was used as the evaluation value.

[ minute hardness ]

The ultra-fine indentation hardness was measured at a depth of 50nm from the surface of the hard coat layer using an ultra-fine indentation hardness tester (NanoinderSA 2, MTS Systems). In the measurement, a triangular pyramid indenter having a tip radius of curvature of 100nm and a ridge angle of 80 ℃ was used as an indenter, and the pressing speed was set to 2.0 nm/s.

[ crimp ]

The prepared hard coat film was cut into a square of 10cm square to prepare a sample, and the sample was placed on a flat surface to stand at 4 corners, and the vertical distance from the flat surface to the tip of the 4 corners was measured. The smaller the measurement value, the smaller the curl.

[ bending test ]

Fig. 2 is a schematic diagram showing a test method of the bending test (cylindrical winding test method). First, a strip of 100mm (width direction of the film) × 30mm (longitudinal direction of the film) was cut out from the hard coat film thus produced, thereby producing a sample. Next, as shown in fig. 2, the prepared sample was wound around a stainless steel cylinder for evaluation (diameter 1 to 40mm (per 1mm)) and held by hand for 5 seconds. At this time, the sample having the hard coat layer formed only on one surface of the transparent substrate was wound with the hard coat layer facing outward (that is, wound such that the surface of the transparent substrate having no hard coat layer was in contact with the stainless steel cylinder for evaluation). Next, the sample peeled off from the stainless steel cylinder for evaluation was lifted up to a position 10cm away from the three-wavelength fluorescent lamp, and the presence or absence of cracks at the wound position was visually observed. When cracks were confirmed, the diameter of the cylinder was increased by one order (1mm) and the same test was performed. The minimum diameter of the stainless steel cylinder for evaluation when no crack was generated in the hard coat layer was used as the evaluation value of the bending test.

As shown in table 1, in examples 1 to 9, hard coatings having all good pencil hardness, fine indentation hardness, curl, and bendability were confirmed by providing hard coatings on both sides of a transparent substrate, setting the thickness of the transparent substrate to 5 to 40 μm, setting the thickness of each hard coating to 5 to 30 μm, setting the total volume of the hard coatings to 40% or more of the total volume of the hard coatings, and setting the total thickness of the hard coatings to 80 μm or less.

In contrast, in comparative examples 1 and 2, since the hard coat layer was provided only on one surface of the transparent base material and the volume ratio of the hard coat layer was less than 40%, the pencil hardness was low and the curl was extremely large.

In comparative examples 3 and 4, although the hard coat layers were provided on both surfaces of the transparent base material, the volume ratio of the hard coat layer was less than 40%, and the pencil hardness was low. In addition, in comparative example 4, the thickness of the transparent base material was more than 40 μm, and the total thickness of the hard coating film was also more than 80 μm, whereby the bendability (resistance to bending) was low.

In comparative examples 5 and 6, since the transparent base material had a layer in which a hard coat layer was provided only on one surface thereof and the thickness of the transparent base material was larger than 40 μm and the total thickness of the hard coat film was larger than 80 μm, the curl was increased and the bendability (resistance to bending) was decreased. In comparative example 5, the volume ratio of the hard coat layer was less than 40%, and therefore, the pencil hardness was also lowered. In comparative example 6, the pencil hardness was improved by increasing the film thickness of the hard coat layer, but the curl became extremely large.

As described above, according to the present invention, it was confirmed that a hard coating film having all of high hardness, low curling properties, and high bendability can be provided.

Industrial applicability

The hard coat film according to the present invention can be used for an image display device and the like.

Description of the reference numerals

1 hard coating film

2 transparent substrate

3a, 3b hard coating