WO2017119391A1

WO2017119391A1 - Optical film, polarizing plate, and image display device

Info

Publication number: WO2017119391A1
Application number: PCT/JP2016/089081
Authority: WO
Inventors: 佐藤　純; 啓志中村; 正隆中島; 智之堀尾
Original assignee: 大日本印刷株式会社
Priority date: 2016-01-08
Filing date: 2016-12-28
Publication date: 2017-07-13
Also published as: JPWO2017119391A1; TWI726966B; JP6773049B2; TW201731691A

Abstract

[Problem] To provide an optical film having exceptional hardness and exceptional folding endurance, and a polarizing plate and an image display device provided with the optical film. [Solution] According to an embodiment of the present invention, there is provided a foldable optical film 10 provided with a light-transmissive resin substrate 11 and a hard coating layer 12 provided on one surface side of the light-transmissive resin substrate 11, wherein the optical film 10 is characterized in having a first region 10B and a second region 10C, the second region 10C having a lower hardness at the surface 10A of the optical film 10 than does the first region 10B.

Description

Optical film, polarizing plate and image display device

Reference to related applications

This application enjoys the benefit of the priority of Japanese Patent Application No. 2016-2954 (filing date: January 8, 2016), which is a prior Japanese application, the entire disclosure of which is incorporated herein by reference. To be part of

The present invention relates to an optical film, a polarizing plate, and an image display device.

In recent years, optical films used for touch panels, which have been rapidly spreading, are required to have excellent hardness and excellent durable folding performance that does not cause cracks even when the optical film is repeatedly folded.

However, since hardness and bendability are usually in a trade-off relationship, with conventional optical films, when the hardness is improved, the durable folding performance is lowered, and when the durable folding performance is improved, the hardness is lowered. Therefore, these performances could not be improved at the same time.

Also, touch panels often use glass for the display screen. However, although glass has high hardness, it cannot be given folding performance because it is broken when folded, and glass is a material with a large specific gravity. When the glass is thinned, there is a problem that the strength is reduced and the glass is easily broken.

Further, as an optical film having hardness and flexibility, a first hard coat layer is provided on one surface of a light-transmitting resin base material, and the first hard coat layer is Vickers hardness on the other surface. An optical film provided with a second hard coat layer having a different thickness is disclosed (for example, see JP-A-2014-186210). However, although such an optical film has excellent hardness, it may not be able to satisfy the durable folding performance required in recent years, because it may be marked by folding when it is repeatedly folded.

The present invention has been made to solve the above problems. That is, it aims at providing the optical film which has the outstanding hardness and the outstanding durable folding performance, a polarizing plate provided with the same, and an image display apparatus.

As a result of intensive research on the above problems, the inventors of the present invention have excellent hardness and excellent folding performance as long as the second region having a lower hardness on the surface of the optical film than the first region is formed. It was found that it can be obtained. The present invention has been completed based on such findings.

According to one aspect of the present invention, a foldable optical film comprising a light transmissive resin base material and a hard coat layer provided on one surface side of the light transmissive resin base material, There is provided an optical film comprising: a first region; and a second region having a lower hardness on the surface of the optical film than the first region.

In the above optical film, even when the test for folding the optical film by 180 ° in the second region so that the bending radius of the optical film is 1.5 mm is repeated 100,000 times, no crack or breakage occurs. Good.

In the optical film, the hard coat layers are a plurality of first hard coat layers that are spaced apart from each other via a gap, and a second hard coat layer having a hardness lower than that of the first hard coat layer. In the first region, the light transmissive resin base material, the first hard coat layer, and the second hard coat layer are laminated in this order, and the second region In the region, the gap may exist, and the second hard coat layer may be embedded in the gap.

In the optical film, the hard coat layer includes a first hard coat layer having one or more recesses, and a second hard coat layer having a hardness lower than that of the first hard coat layer. In the region, the light transmissive resin base material, the first hard coat layer, and the second hard coat layer are laminated in this order, and in the second region, the concave portion And the recess has a region where the thickness of the first hard coat layer is 50% or less of the thickness of the first hard coat layer in the first region, and the first Two hard coat layers may be embedded in the recess.

In the optical film, the width of the region in which the thickness of the first hard coat layer in the second region is 50% or less of the thickness of the first hard coat layer in the first region is 0. It may be 5 mm or more.

In the optical film, a part of the first hard coat layer is present in the second region, and a part of the first hard coat layer is present in the second region. The film thickness of the first hard coat layer may gradually decrease toward the separated position of the hard coat layer or toward the center of the recess.

According to the other aspect of this invention, the foldable polarizing plate provided with said optical film and the polarizer provided in the other surface side of the said light-transmissive base material of the said optical film is provided. .

According to another aspect of the present invention, there is provided a foldable image display device comprising a display element and the optical film or the polarizing plate disposed on the viewer side with respect to the display element.

FIG. 1 is a schematic configuration diagram of an optical film according to the first embodiment. FIG. 2 is a plan view of the optical film according to the first embodiment. FIG. 3 is an enlarged view of a part of the optical film according to the first embodiment. 4 (A) and 4 (B) are diagrams schematically showing a state of the 180 ° folding test. FIG. 5A and FIG. 5B are schematic configuration diagrams of other optical films according to the first embodiment. 6 (A) to 6 (D) are diagrams schematically showing a manufacturing process of the optical film according to the first embodiment. FIG. 7A to FIG. 7D are diagrams schematically showing a manufacturing process of the optical film according to the first embodiment. FIG. 8 is a schematic configuration diagram of a polarizing plate according to the first embodiment. FIG. 9 is a schematic configuration diagram of the image display apparatus according to the first embodiment. FIG. 10 is a schematic configuration diagram of an optical film according to the second embodiment. FIG. 11 is an enlarged view of a part of the optical film according to the second embodiment. FIG. 12A to FIG. 12C are diagrams schematically showing a manufacturing process of the optical film according to the second embodiment. FIG. 13A to FIG. 13C are diagrams schematically showing a manufacturing process of the optical film according to the second embodiment.

Hereinafter, an optical film, a polarizing plate, a display panel, and an image display device according to an embodiment of the present invention will be described with reference to the drawings. In this specification, terms such as “film” and “sheet” are not distinguished from each other only based on the difference in designation. Thus, for example, “film” is used to include a member that may also be referred to as a sheet, and “sheet” is used to include a member that may also be referred to as a film. FIG. 1 is a schematic configuration diagram of an optical film according to the present embodiment, FIG. 2 is a plan view of the optical film according to the present embodiment, and FIG. 3 is an enlarged view of a part of the optical film according to the present embodiment. 4 is a diagram schematically showing a state of the 180 ° folding test, FIG. 5 is a schematic configuration diagram of another optical film according to the present embodiment, and FIGS. 6 and 7 are according to the embodiment. It is a figure which shows the manufacturing process of an optical film typically.

<<<<< Optical Film >>>>
The optical film 10 shown in FIGS. 1 and 2 is foldable, and includes a light-transmitting resin base material 11 and a hard coat layer 12 provided on one surface 11A of the light-transmitting base material 11. Is. In this specification, “foldable” means that when the optical film is folded in a part of the optical film, the optical film is not cracked or broken. In the optical film, when the optical film is folded, if there is a portion where the optical film is not cracked or broken, the optical film can be folded. Further, the “hard coat layer” is a layer that has optical transparency and has a pencil hardness of at least “F” or more in a pencil hardness test specified by JIS K5600-5-4: 1999. The hard coat layer 12 may have other functions such as antifouling properties. In addition, the pencil hardness test in this specification shall be performed with a load of 750 g and a scratching speed of 1 mm / second.

The optical film 10 has a first region 10B and a second region 10C having different hardnesses on the surface 10A of the optical film 10, respectively. Specifically, the hardness of the surface 10A of the optical film 10 is lower in the second region 10C than in the first region 10B. The “surface of the optical film” in the present specification means a surface on one side and the hard coat layer side of the optical film. In addition, since the surface of the optical film in this specification means the surface of one side of an optical film, in order to distinguish the surface on the opposite side to the surface of an optical film in order to distinguish from the surface of the optical film in this specification, Shall be referred to as In the present embodiment, the surface 12A of the hard coat layer 12 is the surface 10A of the optical film 10, but when another functional layer is provided on the hard coat layer 12, the surface of this functional layer. Becomes the surface of the optical film. In the present specification, the “first region” means a region whose hardness on the surface of the optical film is higher than the second region, and the “second region” means that the hardness on the surface of the optical film is the first. It means a region lower than one region.

The hardness of the first region 10B is not particularly limited as long as it is higher than the hardness of the second region 10C. However, when the optical film 10 is used on the surface of an image display device including a touch panel, The surface 10A of the optical film 10 preferably has a pencil hardness of 5H or more, preferably 6H or more when measured by a pencil hardness test specified in JIS K5600-5-4: 1999. More preferably, it is 7H or more. When the optical film 10 is used inside an image display device having a touch panel, the surface 10A of the optical film 10 in the first region 10B is a pencil defined by JIS K5600-5-4: 1999. The pencil hardness as measured by a hardness test is preferably 4H or more, preferably 5H or more, and more preferably 6H or more. The pencil hardness is the highest hardness at which the surface of the optical film was not damaged in the pencil hardness test. The pencil hardness is measured using a plurality of pencils having different hardnesses. The pencil hardness test is performed five times for each pencil, and the surface of the optical film is scratched four times or more out of the five times. If not, it is determined that the surface of the optical film was not scratched with the pencil having this hardness. The above-mentioned scratches refer to those that are visually observed through transmission observation of the surface of the optical film subjected to the pencil hardness test under a fluorescent lamp. Further, in the following pencil hardness, even if not specifically described, the pencil hardness is a pencil hardness as measured by a pencil hardness test specified in JIS K5600-5-4: 1999.

The hardness of the second region 10C is not particularly limited as long as it is lower than the hardness of the first region 10B. However, when the optical film 10 is used on the surface of the image display device including a touch panel, The surface 10A of the optical film 10 has a pencil hardness of preferably 2H or more, preferably 3H or more, and more preferably 4H or more. When the optical film 10 is used inside an image display device including a touch panel, the surface 10A of the optical film 10 preferably has a pencil hardness of H or higher in the second region 10C. Preferably, it is preferably 3H or more. In addition, in order to achieve both excellent hardness and excellent durability folding performance, it is necessary that the hardness of the first region and the hardness of the second region have a difference. In view of this, it is preferable that the difference in hardness between the first region and the second region is smaller. In terms of pencil hardness, the difference between the pencil hardness of the first region and the pencil hardness of the second region is preferably within 5 ranks, more preferably within 3 ranks.

It is preferable that the optical film 10 does not crack or break when the test of folding the optical film 10 180 ° in the second region 10C is repeated 100,000 times so that the bending radius is 1.5 mm. If the optical film 10 is cracked or broken within 100,000 times, the durable folding performance of the optical film 10 becomes insufficient. The folding test can be performed using, for example, an endurance tester (product name “DLDMMLH-FS”, manufactured by Yuasa System Equipment Co., Ltd.).

FIG. 4 is a diagram schematically showing a state in which a part of the optical film 10 is folded by 180 ° (hereinafter also referred to as a durability folding test) so that the bending radius R of the optical film 10 is 1.5 mm. . As shown in FIG. 4 (A), in the endurance folding test, first, in a state in which the optical film 10 is flat, one side of the optical film 10 and another side facing the one side. The sides are fixed to the fixed end 21 and the moving end 22 of the folding tester, which are arranged at predetermined intervals in the horizontal direction. In addition, although an optical film may be arbitrary shapes, it is preferable that the optical film 10 which performs the said durable folding test is a rectangle. Next, as shown in FIG. 4B, the moving end 22 is moved closer to the fixed end 21 and the optical film 10 is folded at 180 ° so that the bending radius R of the optical film 10 is 1.5 mm. Here, the place where the optical film 10 is folded is a place where the second region 10C exists. Then, the state shown in FIGS. 4A and 4B is repeated 100,000 times. Although depending on the size of the optical film, for example, if the distance between the fixed end 21 and the moving end 22 is 3 mm, the optical film 10 is 180 so that the bending radius R of the optical film 10 is 1.5 mm. Can be folded to °.

It is preferable that no cracks or breaks occur when the durability folding test is performed 150,000 times on both sides of the optical film 10 respectively. In addition, the optical film 10 may be one that does not crack or break when the above-described durable folding test is performed on one side, but is broken when the above-described durable folding test is performed on both sides. Alternatively, it is preferable that no breakage occurs. In addition, even if the optical film 10 mentioned above is rotated 90 degree | times and the same durable folding test is done, a crack or a fracture | rupture will not arise similarly.

The optical film 10 preferably has a transmittance of light having a wavelength of 380 nm of 10% or less. When the transmittance exceeds 10%, when the optical film 10 is used in a mobile terminal, the polarizer may be exposed to ultraviolet rays and may be easily deteriorated. The upper limit of the transmittance is more preferably 8% or less, and most preferably 5% or less. The transmittance can be measured using a haze meter (product name “HM-150”, manufactured by Murakami Color Research Laboratory). The transmittance of light having a wavelength of 380 nm is an arithmetic average value obtained by measuring three times.

The optical film 10 preferably has a total light transmittance of 85% or more. If the transmittance is less than 85%, the display screen may be difficult to visually recognize when the optical film 10 is used in a mobile terminal. The lower limit of the total light transmittance is more preferably 90% or less. The total light transmittance can be measured by a method based on JIS K7361-1: 1997 using a haze meter (product name “HM-150”, manufactured by Murakami Color Research Laboratory). The total light transmittance is an arithmetic average value of values obtained by measuring three times.

The haze value of the entire optical film 10 is preferably 2.5% or less. If the haze value exceeds 2.5%, the display screen may be whitened when the optical film 10 is used in a mobile terminal. The haze value is more preferably 1.5% or less, and more preferably 1.0% or less. The haze value can be measured by a method based on JIS K7136: 2000 using a haze meter (product name “HM-150”, manufactured by Murakami Color Research Laboratory). The haze value is the arithmetic average value of the values obtained by measuring three times.

<< light transmissive resin base material >>
The light-transmitting resin base material 11 is not particularly limited as long as it is a base material made of a light-transmitting resin. Examples of the resin having optical transparency include polyamide imide resin, polyimide resin, aramid resin, cellulose acylate resin, cycloolefin resin, polycarbonate resin, acrylate resin, polyester resin, or a mixture of two or more of these resins. Etc. Among these, in addition to being hard to crack or break in the endurance folding test, it also has excellent hardness and transparency, excellent heat resistance, and further improved hardness and transparency by firing. From the viewpoint of imparting a cation, a polyimide resin, an aramid resin, or a mixture thereof is preferable.

Examples of the polyimide resin include compounds having a structure represented by the following formula. In the following formula, n is a repeating unit and represents an integer of 2 or more.

The aramid resin generally has a skeleton represented by the following formulas (18) and (19), and examples of the aramid resin include compounds represented by the following formula (20). . In the following formula, n is a repeating unit and represents an integer of 2 or more.

Commercially available materials may be used as the base material made of polyimide resin or aramid resin represented by the above formulas (1) to (17) and (20). Examples of the commercially available base material made of the polyimide resin include, for example, Neoprim manufactured by Mitsubishi Gas Chemical Co., Ltd., and examples of the commercially available base material made of the aramid resin include, for example, Mikutron manufactured by Toray Industries, Inc. It is done.

Further, the base material made of the polyimide resin or the aramid resin represented by the above formulas (1) to (17) and (20) may be synthesized by a known method. For example, a method for synthesizing a polyimide resin represented by the above formula (1) is described in JP-A-2009-132091. Specifically, 4,4′-hexafluoro represented by the following formula (21) is described. It can be obtained by reacting propylidenebisphthalic dianhydride (FPA) with 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFDB).

The weight average molecular weight of the polyimide resin or aramid resin is preferably in the range of 3000 to 500,000, more preferably in the range of 5000 to 300,000, and still more preferably in the range of 10,000 to 200,000. . When the weight average molecular weight is 3000 or less, sufficient strength may not be obtained. When the weight average molecular weight exceeds 500,000, the viscosity increases and the solubility decreases, so that a substrate with a smooth surface and a uniform film thickness can be obtained. It may not be obtained. In addition, in this specification, a weight average molecular weight is a polystyrene conversion value measured by gel permeation chromatography (GPC).

Among the polyimide resin and the aramid resin, a polyimide resin or an aramid resin having a structure in which charge transfer within a molecule or between molecules hardly occurs is preferable because it has excellent transparency. Specifically, the above formula (1 ) To (8), polyimide resins having an alicyclic structure such as the above formulas (9) to (12), and aramid resins having a halogen group such as the above formula (20).

In addition, the fluorinated polyimide resins such as the above formulas (1) to (8) have a fluorinated structure, and thus have high heat resistance, and are colored by the heat during the production of the substrate made of the polyimide resin. Therefore, it has excellent transparency.

From the viewpoint that the pencil hardness of the hard coat layer 12 can be increased to 5H or more, the light-transmitting resin substrate 11 is a fluorinated polyimide resin represented by the above formulas (1) to (8) or the like, It is preferable to use an aramid resin having a halogen group such as 20) or a base material made of a mixture of these resins. Especially, since the said pencil hardness can provide very excellent hardness of 7H or more, it is more preferable to use the base material which consists of a polyimide resin represented by the said Formula (1).

Examples of the cellulose acylate resin include cellulose triacetate resin and cellulose diacetate resin. Examples of the cycloolefin resin include polymers such as norbornene monomers and monocyclic cycloolefin monomers.

As the triacetyl cellulose resin, in addition to pure triacetyl cellulose, cellulose acetate propionate and cellulose acetate butyrate may be used in combination with components other than acetic acid as a fatty acid forming an ester with cellulose. Further, these triacetylcelluloses may be added with other additives such as other cellulose lower fatty acid esters such as diacetylcellulose, or plasticizers, ultraviolet absorbers, and lubricants as necessary.

Examples of the polycarbonate resin include aromatic polycarbonate resins based on bisphenols (such as bisphenol A) and aliphatic polycarbonate resins such as diethylene glycol bisallyl carbonate.

Examples of the acrylate resins include poly (meth) methyl acrylate resins, poly (meth) ethyl acrylate resins, methyl (meth) acrylate-butyl (meth) acrylate copolymers, and the like.

Examples of the polyester resin include resins containing at least one of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate as constituent components.

The thickness of the light transmissive resin substrate 11 is not particularly limited, but is preferably 10 μm or more and 55 μm or less. If the thickness of the light-transmitting resin substrate 11 is less than 10 μm, the curl of the optical film becomes large, and the hardness may be insufficient, so that the pencil hardness described later cannot be increased to 4H or more. When manufacturing with Roll to Roll, wrinkles are likely to occur, which may lead to deterioration of the appearance. On the other hand, if the thickness of the light-transmitting resin substrate 11 exceeds 55 μm, the folding performance of the optical film may be insufficient, and the requirements for the folding test described later may not be satisfied, and the optical film becomes heavy and lighter. This is not preferable. The thickness of the light transmissive resin base material 11 was measured by measuring the thickness of the light transmissive resin base material 11 at 10 points using a thickness measuring device (product name “Digimatic Indicator IDF-130”, manufactured by Mitutoyo Corporation). It shall mean the arithmetic mean value.

<< Hard coat layer >>
The hard coat layer 12 includes a plurality of first hard coat layers 13 and a second hard coat layer 14 having a hardness lower than that of the first hard coat layer 13. The hardness of the first hard coat layer 13 and the second hard coat layer 14 can be confirmed by measuring the Martens hardness. In this specification, the “Martens hardness” is the hardness when the indenter is pushed in by 500 nm by the hardness measurement by the nanoindentation method. In the present specification, the measurement of the Martens hardness by the nanoindentation method is performed using “TI950 TriboIndenter” manufactured by HYSITRON. That is, a Berkovich indenter (triangular pyramid) as the above indenter is pushed in by 500 nm from the side surfaces of the first hard coat layer 13 and the second hard coat layer 14 under the following measurement conditions, and held for a certain period of time to relieve the residual stress. And then unloading, measuring the maximum load after relaxation, and using the maximum load P _max (μN) and the indentation area A (nm ² ) having a depth of 500 nm, the martens by P _max / A Calculate the hardness. The Martens hardness is the arithmetic average value of the values obtained by measuring 10 locations.
(Measurement condition)
・ Loading speed: 10 nm / second ・ Retention time: 5 seconds ・ Load unloading speed: 10 nm / second ・ Measurement temperature: 25 ° C.

The first hard coat layer 13 is a layer for imparting hardness to the optical film 10, and the Martens hardness at the center of the cross section of the first hard coat layer 13 is preferably 500 MPa or more and less than 1000 MPa. By setting the Martens hardness of the first hard coat layer 13 in the above range, the pencil hardness in the first region can be set to 4H or more. The lower limit of the Martens hardness at the center of the cross section of the first hard coat layer 13 is preferably 600 MPa or more, and the upper limit is preferably 950 MPa or less.

As a method for making the Martens hardness of the first hard coat layer 13 larger than the Martens hardness of the second hard coat layer 14, for example, a content of silica particles to be described later is contained more on the first hard coat layer side. The method of controlling so that, etc. are mentioned.

The second hard coat layer 14 is a layer for imparting the above-mentioned durable foldability and scratch resistance, and the Martens hardness at the center of the cross section of the second hard coat layer 14 is preferably 350 MPa or more and 600 MPa or less. . By setting the Martens hardness of the second hard coat layer 14 within the above range, the surface of the hard coat layer can be applied while having sufficient durability folding performance and applying a load of 1 kg / cm ² with # 0000 steel wool. It is possible to impart extremely excellent scratch resistance such that no scratches are generated in a steel wool test in which reciprocating friction is performed 3500 times. The lower limit of the Martens hardness at the center of the cross section of the second hard coat layer 14 is more preferably 375 MPa, and the upper limit is more preferably 575 MPa.

The first hard coat layers 13 are separated from each other through a gap 15. The shape of the first hard coat layer 13 is not particularly limited, and examples thereof include a stripe shape, a dot shape, a block shape, and a lattice shape. Among these, a stripe shape is preferable from the viewpoint of productivity in continuous coating.

The first hard coat layer 13 shown in FIG. 1 has a stripe shape as shown in FIG. The minimum width of the first hard coat layer 13 corresponding to the width of the first region 10B is preferably 10 mm or more and 1000 mm or less. If the minimum width of the first hard coat layer 13 is less than 10 mm, there is a fear that sufficient hardness cannot be obtained in the image display device provided with the optical film and the touch panel. There is a possibility that a sufficient yield cannot be obtained when processing an image display device including a film and a touch panel. The lower limit of the minimum width of the first hard coat layer 13 is more preferably 20 mm or more, and the upper limit is more preferably 800 mm or less.

The maximum width of the gap 15 corresponding to the width of the second region 10C is preferably 2 mm or more and 50 mm or less. When the maximum width of the gap 15 is less than 2 mm, the first region may be cracked or broken during the endurance folding test. When the width exceeds 50 mm, the image display device including the optical film and the touch panel is provided. There is a possibility that sufficient hardness cannot be obtained. The lower limit of the maximum width of the gap 15 is more preferably 5 mm or more, and the upper limit is more preferably 20 mm or less. The “gap” in the present specification means a space sandwiched between the first hard coat layers.

The first hard coat layer 13 exists at least in the first region 10B, and the gap 15 between the first hard coat layers 13 exists in the second region 10C. The second region 10C having a lower hardness than the first region 10B is formed by causing the gap 15 to exist in the second region 10C and embedding the second hard coat layer 14 in the gap 15 as will be described later. Can do.

In the first region 10B, the thickness of the first hard coat layer 13 is preferably constant. The film thickness of the first hard coat layer 13 in the first region 10B is preferably 2 μm or more and 20 μm or less. If the film thickness of the first hard coat layer in the first region is less than 2 μm, the hardness of the hard coat layer may be reduced, and if it exceeds 20 μm, the thickness is too thick. May deteriorate. The film thickness of the first hard coat layer 13 is obtained by photographing a cross section of the first hard coat layer 13 using a scanning electron microscope (SEM), and in the image of the cross section, the film of the first hard coat layer 13 The thickness is measured at 20 locations, and the arithmetic average value of the film thickness at the 20 locations is taken.

In the second region 10C, as shown in FIG. 3, due to the presence of the gap 15, the film thickness of the first hard coat layer 13 in the second region 10C is the first in the first region 10B. There is a region 10D that is 50% or less of the film thickness of the hard coat layer 13. The width of the region 10D is preferably 0.5 mm or more. By setting the width of the region 10D to 0.5 mm or more, the second hard coat layer 14 embedded between the first hard coat layers 13 increases, so that the durable folding performance can be further improved. The lower limit of the width of the region 10D is more preferably 1 mm or more, and the upper limit is more preferably 45 mm or less. This region 10 D also includes a separated portion where the first hard coat layer 13 does not exist in the second region 10 C.

In the second region 10 C, a part of the first hard coat layer 13 is present, and the film thickness of the first hard coat layer 13 is gradually increased toward the separated portion of the first hard coat layer 13. It is getting smaller. Thus, by gradually reducing the film thickness of the first hard coat layer 13, the interface between the first hard coat layer 13 and the second hard coat layer 14 becomes difficult to be visually recognized.

The second hard coat layer 14 is provided on the first hard coat layer 13 in the first region 10B, and is embedded in the gap between the first hard coat layers 13 in the second region 10C. ing. The film thickness of the second hard coat layer 14 in the first region 10B is preferably 0.5 μm or more and 4 μm or less. If the film thickness of the second hard coat layer in the first region is less than 0.5 μm, the scratch resistance may be reduced. If the film thickness exceeds 4 μm, the second hard coat layer composition Coating may be difficult. The film thickness of the second hard coat layer 14 in the second region 10C is preferably 0.5 μm or more and 20 μm or less. If the film thickness of the second hard coat layer in the second region is less than 0.5 μm, the scratch resistance may be reduced, and if it exceeds 20 μm, sufficient flexibility may not be obtained. is there. The film thickness of the second hard coat layer 14 is measured by the same method as the film thickness of the first hard coat layer 13.

<< first hard coat layer >>
The first hard coat layer 13 preferably contains a binder resin and particles dispersed in the binder resin. Hardness can be improved by dispersing the particles in the binder resin. In addition, the 1st hard-coat layer 13 may contain the ultraviolet absorber.

<Binder resin>
The binder resin contains a polymer (cured product) of a polymerizable compound (curable compound). The polymerizable compound has at least one polymerizable functional group in the molecule. Examples of the polymerizable functional group include ethylenically unsaturated groups such as a (meth) acryloyl group, a vinyl group, and an allyl group. The “(meth) acryloyl group” means to include both “acryloyl group” and “methacryloyl group”.

As the polymerizable compound, polyfunctional (meth) acrylate is preferable. Examples of the polyfunctional (meth) acrylate include trimethylolpropane tri (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, pentaerythritol tri (meth) ) Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, Ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, tripentaerythritol octa (meth) acrylate , Tetrapentaerythritol deca (meth) acrylate, isocyanuric acid tri (meth) acrylate, isocyanuric acid di (meth) acrylate, polyester tri (meth) acrylate, polyester di (meth) acrylate, bisphenol di (meth) acrylate, diglycerin tetra (Meth) acrylate, adamantyl di (meth) acrylate, isobornyl di (meth) acrylate, dicyclopentane di (meth) acrylate, tricyclodecane di (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, and these, PO, Those modified with EO, caprolactone and the like can be mentioned.

Among them, those having 3 to 6 functional groups are preferable because they can satisfy the above-mentioned Martens hardness suitably. For example, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PETTA) Dipentaerythritol pentaacrylate (DPPA), trimethylolpropane tri (meth) acrylate, tripentaerythritol octa (meth) acrylate, tetrapentaerythritol deca (meth) acrylate and the like are preferable.

As the polymerizable compound, in addition to the polyfunctional (meth) acrylate, a polymerizable monomer or a polymerizable oligomer other than the above may be contained. Examples of the polymerizable monomer or polymerizable oligomer include a (meth) acrylate monomer having a polymerizable functional group in the molecule, or a (meth) acrylate oligomer having a polymerizable functional group in the molecule. Examples of the polymerizable monomer or polymerizable oligomer include urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, melamine (meth) acrylate, polyfluoroalkyl (meth) acrylate, and silicone (meth). Examples thereof include monomers or oligomers such as acrylate. These polymerizable monomers or polymerizable oligomers may be used alone or in combination of two or more. Among these, urethane (meth) acrylate having polyfunctionality (6 functionalities or more) and having a weight average molecular weight of 1,000 to 10,000 is preferable.

In addition, a monofunctional (meth) acrylate monomer may be further included for adjusting the hardness, the viscosity of the composition, improving the adhesion, and the like. Examples of the monofunctional (meth) acrylate monomer include hydroxyethyl acrylate (HEA), glycidyl methacrylate, methoxypolyethylene glycol (meth) acrylate, isostearyl (meth) acrylate, 2-acryloyloxyethyl succinate, acryloylmorpholine, N -Acryloyloxyethyl hexahydrophthalimide, cyclohexyl acrylate, tetrahydrofuryl acrylate, isobornyl acrylate, phenoxyethyl acrylate, adamantyl acrylate and the like.

The weight average molecular weight of the polymerizable monomer is preferably less than 1000 and more preferably 200 to 800 from the viewpoint of improving the hardness of the first hard coat layer. Further, the weight average molecular weight of the polymerizable oligomer is preferably 1000 to 20,000, more preferably 1000 to 10,000, and still more preferably 2000 to 7000. In addition, in this specification, the weight average molecular weight of the said polymerizable monomer and polymerizable oligomer is the weight average molecular weight of polystyrene conversion measured by GPC method.

<Particle>
The particles are not particularly limited as long as the hardness can be improved, but silica particles are preferable from the viewpoint of obtaining excellent hardness. Of the silica particles, reactive silica particles are preferred. The reactive silica particles are silica particles that can form a crosslinked structure with the polyfunctional (meth) acrylate, and the first hard coat layer includes the reactive silica particles. Can be sufficiently increased in hardness.

The reactive silica particles preferably have a reactive functional group on the surface, and for example, the polymerizable functional group is preferably used as the reactive functional group.

The reactive silica particles are not particularly limited, and conventionally known reactive silica particles can be used, and examples thereof include reactive silica particles described in JP-A-2008-165040.
Examples of commercially available reactive silica particles include, for example, Nissan Chemical Industries; MIBK-SD, MIBK-SDMS, MIBK-SDL, MIBK-SDZL, JGC Catalysts &Chemicals; V8802, V8803, and the like. .

The silica particles may be spherical silica particles, but are preferably atypical silica particles. Spherical silica particles and atypical silica particles may be mixed. In the present specification, “spherical silica particles” means, for example, silica particles such as true spheres and oval spheres, and “atypical silica particles” have a shape having potato-like random irregularities on the surface. Means silica particles. Since the atypical silica particles have a surface area larger than that of the spherical silica particles, the inclusion of such atypical silica particles increases the contact area with the polyfunctional (meth) acrylate and the hard coat. The layer hardness (pencil hardness) can be made more excellent. Whether or not the atypical silica particles are present can be confirmed by cross-sectional observation of the first hard coat layer using a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM).

The average particle size of the silica particles is preferably 5 nm or more and 200 nm or less. If the thickness is less than 5 nm, it may be difficult to produce the particles themselves, the particles may aggregate together, and it may be extremely difficult to deform the ink. In some stages, the dispersible silica particles may be poorly dispersed and may aggregate. On the other hand, when the average particle diameter of the irregular shaped silica particles exceeds 200 nm, there may be a problem that large irregularities are formed in the hard coat layer or haze is increased. When the silica particles are spherical silica particles, the average particle diameter of the silica particles is 20 particles from the cross-sectional image of the particles taken using a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM). The particle diameter is measured to obtain the arithmetic average value of the particle diameters of 20 particles. When the silica particles are irregularly shaped silica particles, the average particle diameter of the silica particles is the cross-section of the hard coat layer taken using a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM). The maximum value (major axis) and the minimum value (minor axis) of the distance between the two points on the outer periphery of the deformed silica particles are measured from the image, and the average is obtained by calculating the particle diameter. To do.

The hardness (Martens hardness) of the first hard coat layer 13 can be controlled by controlling the size and blending amount of the particles. For example, when the first hard coat layer 13 is formed, the silica particles have a diameter of 5 nm to 200 nm and preferably 25 to 60 parts by mass with respect to 100 parts by mass of the polymerizable compound.

<Ultraviolet absorber>
As will be described later, the optical film is particularly preferably used for a mobile terminal such as a foldable smartphone or a tablet terminal. However, such a mobile terminal is often used outdoors, and thus is displayed more than the optical film. There is a problem that the polarizer disposed on the element side is easily deteriorated by being exposed to ultraviolet rays. However, since the hard coat layer is disposed on the display screen side of the polarizer, if the ultraviolet light absorber is contained in the first hard coat layer, deterioration due to exposure of the polarizer to ultraviolet rays is suitably prevented. can do. In addition, the said ultraviolet absorber (UVA) may be contained in the light transmissive resin base material mentioned above. In this case, the ultraviolet absorber (UVA) may not be contained in the first hard coat layer.

Examples of ultraviolet absorbers include triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and benzotriazole-based ultraviolet absorbers.

Examples of the triazine ultraviolet absorber include 2- (2-hydroxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine. 2- [4-[(2-hydroxy-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2 , 4-Bis [2-hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1,3,5-triazine, 2- [4-[(2-hydroxy-3-tridecyl) Oxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, and 2- [4-[(2-hydroxy-3- ( '- ethyl) hexyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine. Examples of commercially available triazine ultraviolet absorbers include TINUVIN 460, TINUVIN 477 (both manufactured by BASF), LA-46 (manufactured by ADEKA), and the like.

Examples of the benzophenone ultraviolet absorber include 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxy. Examples thereof include benzophenone, 2-hydroxy-4-methoxybenzophenone, hydroxymethoxybenzophenone sulfonic acid and its trihydrate, hydroxymethoxybenzophenone sulfonate sodium, and the like. Examples of commercially available benzophenone ultraviolet absorbers include CHMASSORB81 / FL (manufactured by BASF).

Examples of the benzotriazole ultraviolet absorber include 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate, 2 -(2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl- 6- (tert-butyl) phenol, 2- (2H-benzotriazol-2-yl) -4,6-di-tert-pentylphenol, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3) -Tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy- 3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3 -Tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol) and 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole Etc. Examples of commercially available benzotriazole ultraviolet absorbers include KEMISORB71D, KEMISORB79 (all manufactured by Chemipro Kasei Co., Ltd.), JF-80, JAST-500 (all manufactured by Johoku Chemical Co., Ltd.), ULS-1933D (one side) And RUVA-93 (manufactured by Otsuka Chemical Co., Ltd.).

Among these, triazine ultraviolet absorbers and benzotriazole ultraviolet absorbers are preferably used as the ultraviolet absorber. It is preferable that the ultraviolet absorber has high solubility with the resin component constituting the hard coat layer, and it is preferable that the bleed-out after the above-described durability folding test is small. The ultraviolet absorber is preferably polymerized or oligomerized. As the ultraviolet absorber, a polymer or oligomer having a benzotriazole, triazine, or benzophenone skeleton is preferable. Specifically, (meth) acrylate having a benzotriazole or benzophenone skeleton and methyl methacrylate (MMA) at an arbitrary ratio. It is preferable that it has been heat copolymerized. In addition, when an optical film is applied to an organic light emitting diode), the ultraviolet absorber can also play a role of protecting the OLED from ultraviolet rays.

The content of the ultraviolet absorber is not particularly limited, but is preferably 1 to 6 parts by mass with respect to 100 parts by mass of the solid content of the first hard coat layer composition. If the amount is less than 1 part by mass, the effect of containing the above-described ultraviolet absorber in the hard coat layer may not be sufficiently obtained. If the amount exceeds 6 parts by mass, the hard coat layer may be markedly colored or deteriorated in strength. May occur. The minimum with more preferable content of the said ultraviolet absorber is 2 mass parts, and a more preferable upper limit is 5 mass parts.

<< Second hard coat layer >>
The second hard coat layer 14 contains a resin. The second hard coat layer 14 may contain an ultraviolet absorber in addition to the resin.

<Resin>
The resin contains a polymer (cured product) of a polymerizable compound (curable compound). As the polymerizable compound, since the same compound as the polymerizable compound described in the column of the first hard coat layer 13 can be used, the description is omitted here.

As the polymerizable compound, in addition to the polyfunctional (meth) acrylate monomer, polyfunctional urethane (meth) acrylate and / or polyfunctional epoxy (meth) acrylate may be included.

<Ultraviolet absorber>
As the ultraviolet absorber, the same ultraviolet absorber as described in the column of the first hard coat layer can be used, and the description thereof will be omitted here.

<Other optical films>
In the optical film 10 shown in FIG. 1, the surface 14A of the second hard coat layer 14 in the second region 10C is depressed, but when an optical film is used as the outermost surface of an image display device including a touch panel, As in the optical film 30 shown in FIG. 5A, in the second region 30C, the surface 14A of the second hard coat layer 14 is preferably flat. By making the surface 14A of the second hard coat layer 14 flat, the feel when the surface 14A is touched with a finger is improved. The configuration of the first region 30B is the same as that of the first region 10B, and the second region 30C is the same as the second region 10C except for the above.

Further, in the optical film 10 shown in FIG. 1, a part of the first hard coat layer 13 exists in the second region 10C, but like the optical film 40 shown in FIG. In addition, a part of the first hard coat layer 13 may not be present in the second region 40C. The configuration of the first region 40B is the same as that of the first region 10B, and the second region 40C is the same as the second region 10C except for the above.

<<< Optical Film Manufacturing Method >>>
The optical film 10 can be produced as follows, for example. First, as shown in FIG. 6A, the mask 16 is arranged on the one surface 11A of the light-transmitting resin substrate 11 at predetermined intervals. After the mask 16 is disposed, the first hard coat layer composition is applied onto the one surface 11A of the light-transmitting resin base material 11 by a coating device such as a bar coater, as shown in FIG. As shown, a coating film 17 of the first hard coat layer composition is formed. Although it does not specifically limit as a coating method of the 1st composition for hard-coat layers, The bar-coat method, the gravure printing method, the screen printing method, the spray printing method etc. are mentioned. Further, as a method for forming the first hard coat layer 13, a photolithography method may be used.

<< First composition for hard coat layer >>
The 1st composition for hard-coat layers contains the polymeric compound and particle | grains. The 1st composition for hard-coat layers may contain the ultraviolet absorber, the solvent, and the polymerization initiator as needed.

The first hard coat layer composition preferably has a total solid content of 25 to 55%. If it is lower than 25%, residual solvent may remain or whitening may occur. If it exceeds 55%, the viscosity of the first composition for hard coat layer will increase, the coatability may decrease, and unevenness and streaks may appear on the surface. The solid content is more preferably 30 to 50%.

<Solvent>
Examples of the solvent include alcohols (eg, methanol, ethanol, propanol, isopropanol, n-butanol, s-butanol, t-butanol, benzyl alcohol, PGME, ethylene glycol, diacetone alcohol), ketones (eg, acetone, methyl ethyl ketone, Methyl isobutyl ketone, cyclopentanone, cyclohexanone, heptanone, diisobutyl ketone, diethyl ketone, diacetone alcohol), ester (methyl acetate, ethyl acetate, butyl acetate, n-propyl acetate, isopropyl acetate, methyl formate, PGMEA), aliphatic Hydrocarbons (eg, hexane, cyclohexane), halogenated hydrocarbons (eg, methylene chloride, chloroform, carbon tetrachloride), aromatic hydrocarbons (eg, benzene, toluene, xylene), Amide (eg, dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ether (eg, diethyl ether, dioxane, tetrahydrofuran), ether alcohol (eg, 1-methoxy-2-propanol), carbonate (dimethyl carbonate, diethyl carbonate, Ethyl methyl carbonate), and the like. These solvents may be used alone or two or more of them may be used in combination. Among them, as the solvent, the resin component such as the polymerizable monomer and / or polymerizable oligomer described above, and other additives can be dissolved or dispersed to suitably apply the hard coat layer composition. And methyl isobutyl ketone and methyl ethyl ketone are preferred.

<Polymerization initiator>
The polymerization initiator is a component that is decomposed by light irradiation to generate radicals to initiate or advance polymerization (crosslinking) of the photopolymerizable compound.

The polymerization initiator is not particularly limited as long as it can release a substance that initiates radical polymerization by light irradiation. The polymerization initiator is not particularly limited, and known ones can be used. Specific examples include, for example, acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, thioxanthones, propiophenone. , Benzyls, benzoins, acylphosphine oxides. Further, it is preferable to use a mixture of photosensitizers, and specific examples thereof include n-butylamine, triethylamine, poly-n-butylphosphine and the like.

As the polymerization initiator, when the binder resin is a resin system having a radically polymerizable unsaturated group, it is preferable to use acetophenones, benzophenones, thioxanthones, benzoin, benzoin methyl ether or the like alone or in combination. .

After forming the coating film 17 of the first hard coat layer composition, the max 16 on the light transmissive resin substrate 11 is removed. As a result, as shown in FIG. 6C, the first hard coat layer composition slightly flows into the region where the mask 16 was present, and the film thickness becomes toward the gap 15 between the coating films 17. Gradually lower.

Thereafter, as shown in FIG. 6D, the coating film 17 is dried by heating at a temperature of, for example, 30 ° C. to 120 ° C. for 10 seconds to 12 seconds by various known methods, and the solvent is evaporated.

After the coating film 17 is dried, as shown in FIG. 7A, the coating film 17 of the first hard coat layer composition is irradiated with ionizing radiation such as ultraviolet rays, so that the first hard coat layer The coating film 17 of the composition for use is semi-cured. “Semi-curing” in the present specification means that curing substantially proceeds when irradiated with light. However, at this stage, the coating film 17 of the first hard coat composition may be completely cured (full cure). The “complete curing” in the present specification means that the curing does not substantially proceed even when light is further irradiated. Examples of the ionizing radiation include visible light, ultraviolet light, X-rays, electron beams, α rays, β rays, and γ rays.

After the coating film 17 is semi-cured, as shown in FIG. 7B, a second hard coat layer composition is applied onto the coating film 17 by a coating device such as a bar coater. The coating film 18 of the composition for 2 hard-coat layers is formed.

<< Second composition for hard coat layer >>
The 2nd composition for hard-coat layers contains the polymeric compound. The 2nd composition for hard-coat layers may contain the ultraviolet absorber, the solvent, and the polymerization initiator as needed. Like the first hard coat layer composition, the second hard coat layer composition preferably has a total solid content of 25 to 55%. Since the solvent and the polymerization initiator are the same as the solvent and the polymerization initiator described in the first hard coat layer composition, the description thereof will be omitted here.

After forming the coating film 18 of the composition for the second hard coat layer, as shown in FIG. 7C, the coating film 18 is formed at a temperature of, for example, 30 ° C. or more and 120 ° C. or less by various known methods. The solvent is evaporated by drying by heating for 12 seconds or more.

After the coating film 18 is dried, as shown in FIG. 7D, the coating film 18 of the second composition for hard coat layer is irradiated with ionizing radiation such as ultraviolet rays, so that the first hard coat layer The coating film 17 of the composition for use and the coating film 18 of the composition for the second hard coat layer are completely cured (full cure) to form the first hard coat layer 13 and the second hard coat layer 14. Thereby, the optical film 10 shown in FIG. 1 is obtained.

According to this embodiment, since the hardness in the surface 10A of the optical film 10 is lower in the second region 10C than in the first region 10B, excellent hardness can be obtained in the first region 10B. Further, when the optical film 10 is folded in the second region 10C, excellent durability foldability can be obtained. Thereby, the optical film 10 which has the outstanding hardness and the outstanding durable foldability can be obtained.

According to the present embodiment, since the first hard coat layer 13 exists in the first region 10B, excellent hardness can be obtained. Further, there is a gap 15 between the first hard coat layers 13 in the second region 10C, and the second hard coat layer 14 having a hardness lower than that of the first hard coat layer 13 is embedded in the gap 15. Therefore, when the optical film 10 is folded in the second region 10C, an excellent durability foldability can be obtained. Thereby, the optical film 10 which has the outstanding hardness and the outstanding durable foldability can be obtained.

<<< Polarizing plate >>>
The optical film 10 can be used by being incorporated into a polarizing plate, for example. FIG. 8 is a schematic configuration diagram of a polarizing plate incorporating the optical film according to the present embodiment. As shown in FIG. 8, the polarizing plate 50 includes an optical film 10 that functions as a protective film, a polarizer 51, and a protective film 52 in this order. The polarizer 51 is formed on the other surface 11B of the light transmissive substrate 11. The protective film 52 is provided on the surface opposite to the surface on which the optical film 10 of the polarizer 51 is provided. The protective film 52 may be a retardation film.

The polarizer 51 is a polyvinyl alcohol resin film that is dyed with iodine or a dichroic dye and stretched uniaxially. As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used.

When laminating the optical film 10 and the polarizer 51, it is preferable to saponify the optical film 10 in advance. By performing the saponification treatment, the adhesiveness with the polarizer 51 is improved.

<<< Image display device >>>
The optical film 10 and the polarizing plate 50 can be used by being incorporated into an image display device, for example. FIG. 9 is a schematic configuration diagram of the image display apparatus according to the present embodiment. As shown in FIG. 9, the image display device 60 mainly includes a display element 61 for displaying an image having a touch panel function, and a polarizing plate 50 disposed on the viewer side from the display element 61. Yes. The display element 61 is an organic light emitting diode (OLED). Although the display element 61 has an in-cell structure having a touch panel function inside, a display element that does not have a touch panel function can be used as the display element. In this case, a touch panel may be disposed between the display element and the polarizing plate (on-cell structure).

The optical film 10 is disposed on the viewer side with respect to the display panel 61, and the hard coat layer 12 is disposed on the viewer side with respect to the light transmissive resin substrate 11.

In the image display device 60, the optical film 10 is provided on the polarizing plate 50. However, the present invention is not limited to this, and the optical film 10 may be provided on, for example, a brightness enhancement film, a retardation film, an antistatic film, or the like. .

[Second Embodiment]
Hereinafter, an optical film, a polarizing plate, a display panel, and an image display device according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a schematic configuration diagram of the optical film according to the present embodiment, FIG. 11 is a partially enlarged view of the optical film according to the present embodiment, and FIGS. 12 and 13 are diagrams of the optical film according to the present embodiment. It is a figure which shows a manufacturing process typically.

<<<<< Optical Film >>>>
The optical film 70 shown in FIG. 10 includes a light transmissive resin base 71 and a hard coat layer 72 provided on one surface 71A of the light transmissive resin base 71. Since the physical properties of the optical film 70 are the same as the physical properties of the optical film 10, the description thereof will be omitted here.

The optical film 70 has a first region 70B and a second region 70C having different hardnesses on the surface 70A of the optical film 70, respectively. Specifically, the hardness of the surface 70A of the optical film 70 is lower in the second region 70C than in the first region 70B.

<< light transmissive resin base material >>
Since the light transmissive resin base material 71 is the same as the light transmissive resin base material 11, the description thereof is omitted here.

<< Hard coat layer >>
The hard coat layer 72 includes a first hard coat layer 73 having one or more recesses 73 A, and a second hard coat layer 74 having a hardness lower than that of the first hard coat layer 73. Regarding the hardness, the hardness of the first hard coat layer 73 is the same as the hardness of the first hard coat layer 13, and the hardness of the second hard coat layer 74 is the hardness of the second hard coat layer 14. Therefore, the description is omitted here.

The first hard coat layer 73 has a recess 73A as described above. That is, as shown in FIG. 11, the thin film portion 73 B of the first hard coat layer 73 exists between the bottom surface of the recess 73 A and the light transmissive resin base material 71, and the both sides of the recess 73. There is a thick film portion 73C whose film thickness is thicker than the thin film portion 73B. The second region has a region where the thickness of the first hard coat layer is 50% or less of the thickness of the first hard coat layer in the first region due to the recess 73A. The shape of the recess 73A is not particularly limited, and examples thereof include a stripe shape, a dot shape, a block shape, and a lattice shape. Among these, a stripe shape is preferable from the viewpoint of productivity in continuous coating.

The concave portions 73A and the thick film portions 73C of the first hard coat layer 73 shown in FIG. The width of the thick film portion 73C corresponding to the width of the first region 70B is preferably 10 mm or more and 1000 mm or less. If the width of the thick film portion 73C is less than 10 nm, sufficient hardness may not be obtained in the image display device including the optical film and the touch panel. If the width exceeds 1000 mm, the optical film and the touch panel may be removed. There is a possibility that a sufficient yield cannot be obtained during processing of the image display device provided. The lower limit of the width of the thick film portion 73C is more preferably 20 mm or more, and the upper limit is more preferably 800 mm or less.

The maximum width of the recess 73A corresponding to the width of the second region 70C is preferably 2 mm or more and 50 mm or less. If the maximum width of the recess 73A is less than 2 mm, the first region may be cracked or broken during the endurance folding test. If the maximum width exceeds 50 mm, the image display device includes the optical film and the touch panel. There is a risk that sufficient hardness cannot be obtained. The lower limit of the maximum width of the recess 73A is more preferably 5 mm or more, and the upper limit is more preferably 20 mm or less.

The first hard coat layer 73 is present at least in the first region 70B, and the recess 73A is present in the second region 70C. The second region 70C having a hardness lower than that of the first region 70B is formed by causing the recess 73A to exist in the second region 70C and embedding the second hard coat layer 74 in the recess 73A as will be described later. Can do.

In the first region 70B, the thickness of the thick film portion 73C of the first hard coat layer 73 is preferably constant. The film thickness of the thick film portion 73C of the first hard coat layer 73 in the first region 70B is preferably 2 μm or more and 20 μm or less. If the thickness of the thick film portion of the first hard coat layer in the first region is less than 2 μm, the hardness of the hard coat layer may decrease, and if it exceeds 20 μm, the thickness is too thick. As a result, workability may be deteriorated. The film thickness of the thick film portion 73 C of the first hard coat layer 73 is measured by the same method as the film thickness of the first hard coat layer 13.

In the second region 70C, as shown in FIG. 11, the thickness of the first hard coat layer 73 (thickness of the thin film portion 73B) in the second region 70C is due to the presence of the recess 73A. There is a region 70D that is 50% or less of the film thickness of the first hard coat layer 73 in the first region 70B. The width of the region 70D is preferably 0.5 mm or more. By setting the width of the region 70D to 1 mm or more, the second hard coat layer 74 embedded between the first hard coat layers 73 increases, so that the durable folding performance can be further improved. The lower limit of the width of the region 70D is more preferably 1 mm or more, and the upper limit is more preferably 45 mm or less.

In the second region 70C, the thin film portion 73B of the first hard coat layer 73 exists, and the film thickness of the thin film portion 73B gradually increases toward the central portion of the recess 73A of the first hard coat layer 73. It is getting smaller. Thus, by gradually reducing the film thickness of the thin film portion 73B, the interface between the first hard coat layer 73 and the second hard coat layer 74 becomes difficult to be visually recognized.

The second hard coat layer 74 is provided on the thick film portion 73C in the first region 70B, and is embedded in the recess 73A in the second region 70C. The film thickness of the second hard coat layer 74 in the first region 70B is preferably not less than 0.5 μm and not more than 4 μm. If the film thickness of the second hard coat layer in the first region is less than 0.5 μm, the scratch resistance may be reduced. If the film thickness exceeds 4 μm, the second hard coat layer composition Coating may be difficult. The film thickness of the second hard coat layer 74 is measured by the same method as the film thickness of the first hard coat layer 13. The film thickness of the second hard coat layer 74 in the second region 70C is preferably 0.5 μm or more and 20 μm or less. If the film thickness of the second hard coat layer in the second region is less than 0.5 μm, the scratch resistance may be reduced, and if it exceeds 20 μm, sufficient flexibility may not be obtained. is there.

<Other optical films>
In the optical film 70 shown in FIG. 10, the surface 74A of the second hard coat layer 74 in the second region 70C is depressed, but when an optical film is used as the outermost surface of an image display device including a touch panel, Similar to the optical film 30, the second region preferably has a flat surface of the second hard coat layer. By making the surface of the second hard coat layer flat, the touch when the surface is touched with a finger is good.

Further, in the optical film 70 shown in FIG. 10, a part of the first hard coat layer 73 exists in the second region 70 C, but like the optical film 40, the second film 70 C is in the second region. A part of one hard coat layer may not exist.

<<< Optical Film Manufacturing Method >>>
The optical film 70 can be manufactured as follows, for example. First, as shown in FIG. 12A, a first hard coat layer composition coating film 75 having a recess 75 A is formed on one surface 71 A of the light-transmitting resin substrate 71. Here, the coating film 75 having the recess 75A can be formed by a method similar to the method described in the first embodiment. Specifically, as described in the first embodiment, since the first hard coat layer composition flows into the region where the mask was present when the mask was removed, the width of the maximum was made larger than that in the first embodiment. By narrowing, each coating film is connected by the 1st composition for hard-coat layers which flows at the time of mask removal, and the coating film 75 which has the recessed part 75A can be formed. Moreover, the coating film 75 which has such a recessed part 75A can be formed also by increasing the application quantity of the composition for 1st hard-coat layers rather than 1st Embodiment. It is also possible to form the coating film 75 having the concave portions 75A by a coating apparatus such as a gravure coater. Since the composition for the first hard coat layer is the same as that of the first embodiment, the description thereof will be omitted here.

After forming the coating film 75 of the composition for the first hard coat layer, as shown in FIG. 12B, the coating film 75 is formed at a temperature of, for example, 30 ° C. or more and 120 ° C. or less by various known methods. The solvent is evaporated by drying by heating for 12 seconds or more.

After the coating film 75 is dried, as shown in FIG. 12C, the coating film 75 of the first hard coat layer composition is irradiated with ionizing radiation such as ultraviolet rays, so that the first hard coat layer The coating film 75 of the composition for use is semi-cured (half-cured). At this stage, the coating film 75 of the first hard coat layer composition may be completely cured (full cure).

After the coating film 75 is semi-cured, as shown in FIG. 13A, the second hard coat layer composition is applied onto the coating film 75 by a coating device such as a bar coater. A coating film 76 of the composition for hard coat layer 2 is formed. Since the 2nd composition for hard-coat layers is the same as that of 1st Embodiment, description shall be abbreviate | omitted here.

After forming the coating film 76 of the second hard coat layer composition, as shown in FIG. 13B, the coating film 76 is formed at a temperature of 30 ° C. or more and 120 ° C. or less by various known methods. The solvent is evaporated by drying by heating for 12 seconds or more.

After the coating film 76 is dried, as shown in FIG. 13C, the coating film 76 of the second hard coat layer composition is irradiated with ionizing radiation such as ultraviolet rays, so that the first hard coat layer The first hard coat layer 73 and the second hard coat layer 74 are formed by completely curing (full cure) the coating film 75 of the composition for use and the coating film 76 of the composition for the second hard coat layer.

According to this embodiment, since the hardness in the surface 70A of the optical film 70 is lower in the second region 70C than in the first region 70B, excellent hardness can be obtained in the first region 70B. Further, when the optical film 70 is folded in the second region 70C, excellent durability foldability can be obtained. Thereby, the optical film 70 which has the outstanding hardness and the outstanding durable foldability can be obtained.

According to the present embodiment, since the first hard coat layer 73 is present in the first region 70B, excellent hardness can be obtained. In addition, a recess 73A between the first hard coat layers 73 exists in the second region 70C, and a second hard coat layer 74 having a hardness lower than that of the first hard coat layer 73 is embedded in the recess 73A. Therefore, when the optical film 70 is folded in the second region 70C, an excellent durability foldability can be obtained. Thereby, the optical film 70 which has the outstanding hardness and the outstanding durable foldability can be obtained.

The

optical films

30, 40, and 70 can be used by being incorporated in the polarizing plate and the image display device having the same structure as the polarizing plate 50 and the image display device 60 described in the first embodiment.

In order to describe the present invention in detail, examples will be described below, but the present invention is not limited to these descriptions. In addition, the following “100% solid content conversion value” is a value when the solid content in the solvent diluted product is 100%.

<Preparation of composition for first hard coat layer>
First, each component was mix | blended so that it might become a composition shown below, and the 1st composition for hard-coat layers was obtained.

(First hard coat layer composition)
-Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (product name "M403", manufactured by Toa Gosei Co., Ltd.): 25 parts by mass-Dipentaerythritol EO-modified hexaacrylate (product name "A-DPH-6E", new Nakamura Chemical Co., Ltd.): 25 parts by mass, deformed silica particles (average particle size 25 nm, manufactured by JGC Catalysts & Chemicals Co., Ltd.): 50 parts by mass (converted to 100% solid content)
Photopolymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name “Irgacure (registered trademark) 184”, manufactured by BASF Japan): 4 parts by mass Fluorine leveling agent (product name “F568”, manufactured by DIC): 0.2 parts by mass (converted to 100% solid content)
・ Methyl isobutyl ketone: 150 parts by mass

(Second hard coat layer composition)
-Urethane acrylate (product name "UX5000", Nippon Kayaku Co., Ltd.): 25 parts by mass-Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (product name "M403", manufactured by Toa Gosei Co., Ltd.): 50 parts by mass・ Polyfunctional acrylate polymer (Product name “Acryt 8KX-012C”, manufactured by Taisei Fine Chemical Co., Ltd.): 25 parts by mass (converted to 100% solid content)
Antifouling agent (product name “BYKUV3500”, manufactured by Big Chemie): 1.5 parts by mass (converted to 100% solid content)
Photopolymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name “Irgacure (registered trademark) 184” manufactured by BASF Japan Ltd.): 4 parts by mass Methyl isobutyl ketone: 150 parts by mass

<Example 1>
A polyimide substrate made of a polyimide resin represented by the above formula (1) having a thickness of 30 μm and a width of 300 mm is prepared as a light-transmitting resin substrate, and the width direction of the polyimide substrate is formed on one surface of the polyimide substrate. A plurality of rectangular masks having a width of 10 mm, a length of 300 mm and a thickness of 0.06 mm are arranged at intervals of 10 cm, and in that state, the first hard coat layer composition is applied with a bar coater, A coating film was formed. After forming the coating film, the mask was removed. Then, the solvent in the coating film is evaporated by heating the formed coating film at 70 ° C. for 1 minute, and ultraviolet rays are removed from the air using an ultraviolet irradiation device (Fusion UV System Japan, light source H bulb). The coating film was semi-cured by irradiation so that the integrated light amount was 100 mJ / cm ² .

Next, the second hard coat layer composition was applied onto the semi-cured coating film with a bar coater to form a coating film. Next, the solvent in the coating film is evaporated by heating the formed coating film at 70 ° C. for 1 minute, and ultraviolet rays are converted into oxygen concentration by using an ultraviolet irradiation device (light source H bulb manufactured by Fusion UV System Japan). Is irradiated with an integrated light amount of 200 mJ / cm ² under a condition of 200 ppm or less to completely cure the coating film, thereby providing a plurality of first hard coat layers having a film thickness of 7 μm and a first hard coat A hard coat layer comprising a second hard coat layer having a thickness of 2 μm was formed on the layer. Thereby, the second hard coat layer is embedded in the gap between the first region where the polyimide base material, the first hard coat layer, and the second hard coat layer are arranged in this order, and the first hard coat layer. Thus, an optical film having a second region in which the hardness of the surface of the hard coat layer is lower than the first region was obtained. The width of the gap between the first hard coat layers is 5 mm near the interface with the narrowest polyimide substrate, 12 mm at the widest second hard coat layer side, and between the first hard coat layers. The second hard coat layer was embedded in the gap. In the second region including the gap, the width of the region where the thickness of the first hard coat layer is 50% or less of the thickness of the first hard coat layer in the first region was 8 mm.

<Example 2>
In Example 2, an optical film was produced in the same manner as in Example 1 except that the film thickness of the first hard coat layer was changed from 7 μm to 20 μm. In the optical film according to Example 2, there was a gap between the first hard coat layers, and the second hard coat layer was embedded in the gap. In the second region including the gap, the width of the region where the thickness of the first hard coat layer is 50% or less of the thickness of the first hard coat layer in the first region was 7 mm.

<Example 3>
In Example 3, the thickness of the first hard coat layer was changed from 7 μm to 20 μm, and the thickness of the second hard coat layer was changed from 2 μm to 4 μm. An optical film was prepared. In the optical film according to Example 3, a gap was present between the first hard coat layers, and the second hard coat layer was embedded in the gap. In the second region including the gap, the width of the region where the film thickness of the first hard coat layer is 50% or less of the film thickness of the first hard coat layer in the first region was 7 mm.

<Example 4>
In Example 4, an optical film was produced in the same manner as in Example 1 except that the film thickness of the second hard coat layer was changed from 2 μm to 0.5 μm.

<Example 5>
Example 5 was the same as Example 1 except that a mask having a width of 8 mm, a length of 300 mm and a thickness of 0.06 mm was used instead of a mask having a width of 10 mm, a length of 300 mm and a thickness of 0.06 mm. Thus, an optical film was produced. In the optical film according to Example 5, there was a gap between the first hard coat layers, and the second hard coat layer was embedded in the gap. In the second region including the gap, the width of the region where the thickness of the first hard coat layer is 50% or less of the thickness of the first hard coat layer in the first region was 6 mm.

<Example 6>
In Example 6, a mask having a width of 5 mm, a length of 300 mm, and a thickness of 0.06 mm was used instead of a mask having a width of 10 mm, a length of 300 mm, and a thickness of 0.06 mm. Thus, an optical film was produced. In the optical film according to Example 6, there was a gap between the first hard coat layers, and the second hard coat layer was embedded in the gap. Further, in the second region including the gap, the width of the region where the thickness of the first hard coat layer is 50% or less of the thickness of the first hard coat layer in the first region was 3 mm.

<Example 7>
In Example 7, the film thickness of the first hard coat layer was changed from 7 μm to 2 μm, and the film thickness of the second hard coat layer was changed from 2 μm to 0.5 μm. Thus, an optical film was produced. In the optical film according to Example 7, there was a gap between the first hard coat layers, and the second hard coat layer was embedded in the gap. In the second region including the gap, the width of the region in which the film thickness of the first hard coat layer is 50% or less of the film thickness of the first hard coat layer in the first region was 9 mm.

<Example 8>
In Example 8, an optical film was produced in the same manner as in Example 1 except that a polyethylene terephthalate substrate having a thickness of 30 μm and a width of 300 mm was used instead of the polyimide substrate.

<Example 9>
In Example 9, an optical film was produced in the same manner as in Example 1 except that a triacetylcellulose substrate having a thickness of 30 μm and a width of 300 mm was used instead of the polyimide substrate.

<Example 10>
A polyimide substrate made of a polyimide resin represented by the above formula (1) having a thickness of 30 μm and a width of 300 mm is prepared as a light-transmitting resin substrate, and the width direction of the polyimide substrate is formed on one surface of the polyimide substrate. A plurality of rectangular masks having a width of 2 mm, a length of 300 mm, and a thickness of 0.06 mm are arranged at intervals of 10 cm along the above, and in this state, the first hard coat layer composition is applied with a bar coater, A coating film was formed. After forming the coating film, the mask was removed. Then, the solvent in the coating film is evaporated by heating the formed coating film at 70 ° C. for 1 minute, and ultraviolet rays are removed from the air using an ultraviolet irradiation device (Fusion UV System Japan, light source H bulb). The coating film was semi-cured by irradiation so that the integrated light amount was 100 mJ / cm ² .

Next, the second hard coat layer composition was applied onto the semi-cured coating film with a bar coater to form a coating film. Next, the solvent in the coating film is evaporated by heating the formed coating film at 70 ° C. for 1 minute, and ultraviolet rays are converted into oxygen concentration by using an ultraviolet irradiation device (light source H bulb manufactured by Fusion UV System Japan). Is irradiated with a cumulative light quantity of 200 mJ / cm ² under a condition of 200 ppm or less to completely cure the coating, thereby providing a first hard part having a recess and a thick film part having a thickness of 7 μm. A hard coat layer comprising a coat layer and a second hard coat layer having a thickness of 2 μm was formed on the first hard coat layer. As a result, the polyimide substrate, the first hard coat layer thick film portion, and the second hard coat layer are disposed in this order in the first region, and the second hard coat layer is recessed in the first hard coat layer. An optical film having a second region in which the coat layer was embedded and the hardness of the surface of the hard coat layer was lower than the first region was obtained. The entrance width of the recess between the first hard coat layers is 3 mm, and the thinnest part of the thin film portion of the first hard coat layer (the portion immediately below the bottom surface of the recess of the first hard coat layer) The thickness was 1 μm. In the second region including the recess, the width of the region in which the thickness of the first hard coat layer is 50% or less of the thickness of the first hard coat layer in the first region was 1 mm.

<Comparative Example 1>
A polyimide substrate made of a polyimide resin represented by the above formula (1) having a thickness of 30 μm and a width of 300 mm is prepared as a light-transmitting resin substrate. The hard coat layer composition was applied to form a coating film. Thereafter, the formed coating film is heated at 70 ° C. for 1 minute to evaporate the solvent in the coating film. The coating film was semi-cured by irradiation so that the integrated light amount was 100 mJ / cm ² .

Next, the second hard coat layer composition was applied onto the semi-cured coating film with a bar coater to form a coating film. Next, the solvent in the coating film is evaporated by heating the formed coating film at 70 ° C. for 1 minute, and ultraviolet rays are converted into oxygen concentration by using an ultraviolet irradiation device (light source H bulb manufactured by Fusion UV System Japan). The film was completely cured by irradiation so that the integrated light amount was 200 mJ / cm ² under the condition of 200 ppm or less. As a result, an optical film having a uniform first hard coat layer having a thickness of 7 μm on the polyimide substrate and a uniform second hard coat layer having a thickness of 2 μm on the first hard coat layer was obtained.

<Comparative Example 2>
A polyimide substrate made of a polyimide resin represented by the above formula (1) having a thickness of 30 μm and a width of 300 mm is prepared as a light-transmitting resin substrate. The hard coat layer composition was applied to form a coating film. Then, the solvent in the coating film is evaporated by heating the formed coating film at 70 ° C. for 1 minute, and ultraviolet rays are converted into oxygen by using an ultraviolet irradiation device (light source H bulb manufactured by Fusion UV System Japan). The coating film was cured by irradiation so that the integrated light amount was 200 mJ / cm ² under the condition where the concentration was 200 ppm or less. Thereby, the optical film which has only a uniform 1st hard-coat layer with a film thickness of 7 micrometers on the polyimide base material was obtained.

<Comparative Example 3>
A polyimide substrate made of a polyimide resin represented by the above formula (1) having a thickness of 30 μm and a width of 300 mm is prepared as a light-transmitting resin substrate, and the second substrate is coated with a bar coater on one surface of the polyimide substrate. The hard coat layer composition was applied to form a coating film. Then, the solvent in the coating film is evaporated by heating the formed coating film at 70 ° C. for 1 minute, and ultraviolet rays are converted into oxygen by using an ultraviolet irradiation device (light source H bulb manufactured by Fusion UV System Japan). The coating film was cured by irradiation so that the integrated light amount was 200 mJ / cm ² under the condition where the concentration was 200 ppm or less. Thereby, the optical film which has only a uniform 2nd hard-coat layer with a film thickness of 2 micrometers on the polyimide base material was obtained.

<Pencil hardness>
The pencil hardness of the first region and the second region on the surface of the optical film according to the example is determined by a pencil hardness test (load: 750 g, scratching speed: 1 mm / second) defined in JIS K5600-5-4: 1999. Based on each measurement. Further, the pencil hardness of the surface of the optical film according to the comparative example was measured based on a pencil hardness test (load: 750 g, scratching speed: 1 mm / second) defined by JIS K5600-5-4: 1999. In the optical film according to the comparative example, since the first hard coat layer and the second hard coat layer were uniformly formed, there was no region where the hardness changed on the surface of the optical film. For this reason, in Table 1, the surface hardness of the optical film according to the comparative example is described only in the column of the first region. The pencil hardness is the highest hardness at which the surface of the optical film was not damaged in the pencil hardness test. The pencil hardness is measured using a plurality of pencils having different hardnesses. The pencil hardness test is performed five times for each pencil, and the surface of the optical film is measured under a fluorescent lamp four times or more out of five times. In the case where no scratch is visually recognized on the surface of the optical film during the transmission observation, it is determined that the surface of the optical film is not scratched with the pencil having this hardness.

<Martens hardness>
The Martens hardness of the first hard coat layer and / or the second hard coat layer of the optical films according to Examples and Comparative Examples was measured. Martens hardness was measured using “TI950 TriboIndenter” manufactured by HYSITRON. Specifically, using a Berkovich indenter (triangular pyramid) as an indenter, pushing in from the side surface of each hard coat layer by 500 nm under the following measurement conditions, holding for a certain period of time to relieve the residual stress, then unloading Then, the maximum load after relaxation was measured, and the Martens hardness was calculated from P _max / A using the maximum load P _max (μN) and the indentation area A (nm ² ) having a depth of 500 nm. The Martens hardness was an arithmetic average value of values obtained by measuring 10 locations.
(Measurement condition)
・ Loading speed: 10 nm / second ・ Retention time: 5 seconds ・ Load unloading speed: 10 nm / second ・ Measurement temperature: 25 ° C.

<Durable folding test>
Samples prepared by cutting optical films according to Examples and Comparative Examples into a rectangular shape of 30 mm × 100 mm were placed on the fixed end and moving end of a durability tester (product name “DLDMMLH-FS, manufactured by Yuasa System Equipment Co., Ltd.”). A test in which the sample is folded at 180 ° by moving the mounting and moving ends so that the surface on which the hard coat layer of the sample is formed is inward and the bending radius of the sample is 1.5 mm (diameter: 3.0 mm) The sample according to the example was folded in the second region.

Thereafter, the sample is replaced with a new sample, and similarly, the sample is folded by 180 ° so that the surface on which the hard coat layer is formed is the outside and the bending radius of the sample is 1.5 mm (diameter: 3.0 mm). The test was conducted 100,000 times and evaluated according to the following criteria. Also in this case, the sample according to the example is folded in the second region.
◯: Even when the above test was performed on both sides of the sample, the sample was not cracked or broken.
X: When the above test was performed on both sides of the sample, the sample was cracked or broken.

<Steel Wool (SW) resistance>
Surface of hard coat layer of optical film according to examples and comparative examples (surface of second hard coat layer when second hard coat layer is present, surface of second hard coat layer when second hard coat layer is not present The surface of 1 hard coat layer) is 3500 at a speed of 50 mm / sec while applying a load of 1 kg / cm ² using # 0000 steel wool (product name “BON STAR”, manufactured by Nippon Steel Wool). After reciprocating friction, the surface of the subsequent hard coat layer was visually checked for the presence or absence of scratches and evaluated according to the following criteria.
○: No scratch was confirmed.
X: Scratches were confirmed.

The results are shown in Table 1.

The following describes the results. In the optical films according to Comparative Examples 1 and 2, although the pencil hardness was high, the results of the durability foldability test and the SW resistance were inferior. Moreover, in the optical film which concerns on the comparative example 3, although the result of a durable foldability test and SW resistance was favorable, pencil hardness was low. On the other hand, in the optical films according to Examples 1 to 10, the pencil hardness in the first region was high, and the results of the durability foldability test and the SW resistance were good.

DESCRIPTION OF

SYMBOLS

10, 30, 40, 70 ...

Optical film

10A, 70A ...

Surface

11, 71 ... Light transmissive

resin base material

12, 72 ...

Hard coat layer

13, 73 ... 1st

hard coat layer

14, 74 ... 2nd hard Coat layer 50 ... Polarizing plate 51 ... Polarizer 60 ... Image display device 61 ... Display element

Claims

A foldable optical film comprising a light transmissive resin base material and a hard coat layer provided on one surface side of the light transmissive resin base material,
An optical film comprising: a first region; and a second region having a lower hardness on the surface of the optical film than the first region.
2. The crack according to claim 1, wherein the optical film is not cracked or broken when the test of folding the optical film by 180 ° in the second region so as to have a bending radius of 1.5 mm is repeated 100,000 times. Optical film.
The hard coat layer has a plurality of first hard coat layers disposed apart from each other through a gap, and a second hard coat layer having a hardness lower than that of the first hard coat layer,
In the first region, the light-transmitting resin base material, the first hard coat layer, and the second hard coat layer are laminated in this order,
The optical film according to claim 1, wherein the gap is present in the second region, and the second hard coat layer is embedded in the gap.
The hard coat layer has a first hard coat layer having one or more recesses, and a second hard coat layer having a hardness lower than that of the first hard coat layer,
In the first region, the light-transmitting resin base material, the first hard coat layer, and the second hard coat layer are laminated in this order,
The recess is present in the second region, and the thickness of the first hard coat layer is 50% of the thickness of the first hard coat layer in the first region due to the recess. The optical film according to claim 1, wherein the optical film has a region to be described below, and the second hard coat layer is embedded in the recess.
The width of the region where the film thickness of the first hard coat layer in the second region is 50% or less of the film thickness of the first hard coat layer in the first region is 0.5 mm or more. The optical film according to claim 3 or 4.
A part of the first hard coat layer exists in the second region, and a part of the first hard coat layer present in the second region is separated from the first hard coat layer. The optical film according to claim 3 or 4, wherein the film thickness of the first hard coat layer is gradually reduced toward the position or the center of the concave portion.
An optical film according to claim 1;
A foldable polarizing plate comprising: a polarizer provided on the other surface side of the light transmissive substrate of the optical film.
A display element;
The optical film according to claim 1 or the polarizing plate according to claim 7, which is disposed closer to the viewer than the display element,
A foldable image display device comprising:
The image display device according to claim 8, wherein the display element includes an organic light emitting diode.
The image display device according to claim 8, wherein the display element has a touch panel function.