WO2020080258A1

WO2020080258A1 - Viewing angle expansion film, polarizing plate, liquid crystal display device, and method for manufacturing viewing angle expansion film

Info

Publication number: WO2020080258A1
Application number: PCT/JP2019/040089
Authority: WO
Inventors: 寛哉西岡
Original assignee: 日本ゼオン株式会社
Priority date: 2018-10-19
Filing date: 2019-10-10
Publication date: 2020-04-23
Also published as: TW202028781A

Abstract

A viewing angle expansion film for expanding a viewing angle, wherein the viewing angle expansion film is provided with a plurality of hole-including parts on at least one surface thereof and has a rectangular shape, the hole-including parts include holes, and the longitudinal direction of the hole-including parts is angled 3° to 45° with respect to the short-side direction of the viewing angle expansion film, or 3° to 45° with respect to the long-side direction of the viewing angle expansion film. Also provided are a polarizing plate and a liquid crystal display device provided with the viewing angle expansion film, and a method for manufacturing a viewing angle expansion film.

Description

Viewing angle widening film, polarizing plate, liquid crystal display device, and method for manufacturing viewing angle widening film

The present invention relates to a viewing angle widening film, a polarizing plate, a liquid crystal display device, and a manufacturing method of the viewing angle widening film.

The TN mode and VA mode liquid crystal display devices have established technology and can be supplied at a relatively low cost, but on the other hand, the display quality is poor when the display surface is observed from an oblique direction, and the usable viewing angle is often narrow. . Specifically, the relationship between the brightness of the image displayed on the screen and the luminance measured by observing the image is significantly different between the case of observing from the front and the case of observing from an oblique direction. It can be difficult to see. For this reason, the TN-mode liquid crystal display device has been conventionally mainly used for a display device such as a small-to-medium-sized television or a personal computer which is viewed from a fixed angle. However, in recent years, it has been attempted to use a liquid crystal display of these modes together with a means for enlarging the viewing angle even in a device such as a tablet terminal that requires visibility in a wide viewing angle.

As an example of means for enlarging the viewing angle, a retardation layer having a specific phase difference and thereby compensating for the viewing angle is known. In addition, various proposals have been made regarding a method of manufacturing such a retardation layer (for example, Patent Documents 1 and 2).

JP-A-2013-151162 (corresponding publication: US Patent Application Publication No. 2002/180107) International Publication No. 2009/084661 (Corresponding Publication: US Patent Application Publication No. 2011/039084)

However, there is a demand for a display device that can realize good display in a wider viewing angle. Specifically, there is a demand for a display device that maintains the contrast ratio of a liquid crystal display device at a high level and that has a gradation luminance characteristic observed from an oblique direction close to a gradation luminance characteristic observed from the front. Here, the gradation brightness characteristic refers to the relationship between the brightness of the image displayed on the screen and the brightness measured by observing the image.
Further, in display devices, improvement in color glare (a phenomenon such as moire interference) is also required, and a viewing angle widening film capable of eliminating such a phenomenon is required.
Therefore, an object of the present invention is to provide a high-contrast ratio and a wide-angle viewing angle, and to provide a viewing angle widening film capable of eliminating a moire interference phenomenon, a manufacturing method thereof, a polarizing plate, and a liquid crystal display device. With the goal.

As a result of studies to solve the above-mentioned problems, the present inventor has found that the above-mentioned problems can be solved by providing a hole-containing portion in a specific mode on at least one surface of the viewing angle widening film. Specifically, the hole-containing portion is provided such that the longitudinal direction of the hole-containing portion is inclined within a predetermined angle range with respect to the short side direction of the viewing angle widening film or the long side direction of the viewing angle widening film. It has been found that the above can solve the above problems. Based on such knowledge, the present inventor has completed the present invention.
That is, the present invention is as follows.

[1] A viewing angle expansion film for expanding the viewing angle,
The viewing angle widening film comprises a plurality of hole-containing portions on at least one surface, and is rectangular,
The hole-containing portion contains holes,
The longitudinal direction of the hole-containing portion is 3 ° or more and 45 ° or less with respect to the short side direction of the viewing angle widening film, or 3 ° or more and 45 ° or less with respect to the long side direction of the viewing angle widening film. A viewing angle expansion film.
[2] The longitudinal direction of the hole-containing portion is 5 ° or more and 15 ° or less with respect to the short side direction of the viewing angle widening film, or 5 ° or more and 15 ° with respect to the long side direction of the viewing angle widening film. The viewing angle widening film according to [1], which is at most °.
[3] Two or more resin layers are provided,
The viewing angle widening film according to [1] or [2], wherein at least one of the resin layers is a layer including the hole-containing portion.
[4] The viewing angle widening film according to any one of [1] to [3], wherein the viewing angle widening film is a polarizing plate protective film.
[5] The viewing angle widening film according to any one of [1] to [4], wherein the hole-containing portion is made of craze.
[6] A polarizing plate comprising the viewing angle widening film according to any one of [1] to [5] and a polarizer.
[7] The angle formed by the longitudinal direction of the hole-containing portion and the direction parallel to the absorption axis of the polarizer is 3 ° or more and 45 ° or less, or the longitudinal direction of the hole-containing portion and the absorption axis of the polarizer are The polarizing plate according to [6], which forms an angle of 3 ° or more and 45 ° or less with a vertical direction.
[8] The angle formed by the absorption axis of the polarizer and the longitudinal direction of the hole-containing portion is 45 ° + θ1,
The polarizing plate according to [6], wherein the θ1 is 3 ° or more and 45 ° or less.
[9] A TN mode liquid crystal display device comprising the polarizing plate according to [6] or [8] and a TN mode liquid crystal cell in this order from the viewing side,
The polarizing plate is arranged such that the surface on the viewing angle widening film side is the viewing side,
The angle formed by the azimuth angle that causes gradation inversion when the display screen is viewed from an oblique direction and the longitudinal direction of the hole-containing portion is 90 ° + θ1.
A TN-mode liquid crystal display device in which θ1 is 3 ° or more and 45 ° or less.
[10] A VA-mode liquid crystal display device comprising the polarizing plate according to [6] or [7] and a VA-mode liquid crystal cell in this order from the viewing side,
The polarizing plate is arranged such that the surface on the viewing angle widening film side is the viewing side,
A VA mode liquid crystal display device, wherein an angle formed by a longitudinal direction of the hole-containing portion and a direction perpendicular to an absorption axis of the polarizer is 3 ° or more and 45 ° or less.
[11] An IPS mode liquid crystal display device comprising the polarizing plate according to [6] or [7] and a liquid crystal cell of IPS mode in this order from the viewing side,
The polarizing plate is arranged such that the surface on the viewing angle widening film side is the viewing side,
An IPS-mode liquid crystal display device, wherein an angle formed by a longitudinal direction of the hole-containing portion and a direction perpendicular to an absorption axis of the polarizer is 3 ° or more and 45 ° or less.
[12] A method for producing a viewing angle widening film according to any one of [1] to [5],
Step 1 of forming the hole-containing portion on at least one surface of the first film,
A method for producing a viewing angle widening film, which comprises a step 2 of stretching the first film subjected to the step 1 to expand the hole diameter of the hole containing portion.
[13] The method for producing a viewing angle widening film according to [12], wherein in the step 2, the first film is obliquely stretched.
[14] The first film includes one or more resin layers,
In the step 1, the hole-containing portion is formed in one or more layers of the resin layer,
In the step 2, the viewing angle according to [12] or [13], wherein the first film is stretched at a temperature lower than a glass transition temperature of a resin forming a resin layer in which the hole-containing portion is formed. Enlarged film manufacturing method.

According to the present invention, there is provided a viewing angle widening film, a method of manufacturing the film, a polarizing plate, and a liquid crystal display device, which have both a high contrast ratio and a wide viewing angle and can eliminate the moire interference phenomenon.

FIG. 1 is a plan view schematically showing an example of a viewing angle widening film. FIG. 2 is an enlarged schematic diagram schematically showing a hole-containing portion observed when the viewing angle widening film is observed in a plane. FIG. 3 is an enlarged schematic view showing an example of the structure of the craze. FIG. 4 is a perspective view schematically showing an example of the craze processing apparatus. FIG. 5 is a side view schematically showing the vicinity of the blade of FIG. 4 in an enlarged manner. FIG. 6 is a plan view schematically showing the first film having a hole-containing portion.

Hereinafter, the present invention will be described in detail by showing embodiments and exemplifications. However, the present invention is not limited to the embodiments and exemplifications shown below, and may be implemented by being arbitrarily modified within the scope of the claims of the present invention and the scope of equivalents thereof.

In the following description, “polarizing plate” includes not only a rigid member but also a flexible member such as a resin film.

In the following description, the directions of the constituent elements are “parallel”, “vertical” or “orthogonal” unless otherwise specified, within a range that does not impair the effects of the present invention, for example, usually ± 5 °, preferably ± 2. The error may be included in the range of 0 °, more preferably ± 1 °.

In the following description, the MD direction (machine direction) is the flow direction of the film in the manufacturing line, and the TD direction (traverse direction) is the direction parallel to the film surface and perpendicular to the MD direction. is there. Further, for convenience, the longitudinal direction of a long film may be referred to as the MD direction of the film, and the width direction may be referred to as the TD direction of the film. In the following description, the "long" film means a film having a length of 5 times or more, preferably 10 times or more, and specifically a roll, with respect to the width. A film having such a length that it can be wound into a shape and stored or transported. The upper limit of the length of the long film is not particularly limited and may be, for example, 100,000 times or less the width.

In the following description, the in-plane retardation Re of a film such as a viewing angle widening film is a value represented by Re = (nx−ny) × d unless otherwise specified. Further, the retardation Rth in the thickness direction of the film is a value represented by Rth = {(nx + ny) / 2-nz} × d unless otherwise specified. Here, nx represents a refractive index in a direction perpendicular to the in-plane direction of the film, that is, the thickness direction and giving the maximum refractive index. ny represents the refractive index in the in-plane direction and in the direction orthogonal to the nx direction. nz represents the refractive index in the thickness direction. d represents the thickness of the film. The measurement wavelength is 590 nm unless otherwise specified.

[1. Overview of viewing angle widening film)
The viewing angle widening film of the present invention is a film for widening the viewing angle of a liquid crystal display device.
The viewing angle widening film of the present invention has a plurality of hole-containing portions on at least one surface and has a rectangular shape. In the present invention, the rectangular shape may include a sheet and a long shape.

In the viewing angle widening film of the present invention, the hole-containing portion contains holes, and the longitudinal direction of the hole-containing portion is 3 ° or more and 45 ° or less with respect to the short side direction of the viewing angle widening film, or the viewing angle is widened. It is 3 ° or more and 45 ° or less with respect to the long side direction of the film. By providing the longitudinal direction of the hole-containing portion at a predetermined angle with respect to the short side direction of the viewing angle widening film or the long side direction of the viewing angle widening film, the moire interference phenomenon can be eliminated.

[2. Pore-containing part]
The viewing angle widening film of the present invention includes a plurality of hole-containing parts, and the hole-containing parts contain holes.
FIG. 1 is a plan view schematically showing an example of a viewing angle widening film. In the example of FIG. 1, the long viewing angle widening film 1 includes a plurality of linear hole-containing portions 20 that are parallel to each other. Although each of the hole-containing portions 20 is illustrated as a single thin line in FIG. 1, the hole-containing portion 20 is a region having a width and a depth, in which a large number of holes (not shown in FIG. 1) are included. ) Is provided.

In FIG. 1, the hole-containing portion 20 shows a mode in which the hole-containing portion 20 is formed from one end of the viewing angle widening film 1 to the other end opposite to the end. It may be formed from one end of the viewing angle widening film to a position not reaching the other end, or may be formed at a position not reaching any end of the viewing angle widening film.

In FIG. 1, θ1a indicates an angle with respect to the longitudinal direction of the hole-containing portion 20 (direction indicated by Y1-Y1) and the short side direction of the viewing angle widening film 1 (direction indicated by XX line). Further, in FIG. 1, θ1b represents an angle formed by the longitudinal direction of the hole-containing portion 20 (direction indicated by Y1-Y1) and the long side direction of the viewing angle widening film 1 (direction indicated by ZZ line).

The example shown in FIG. 1 is an example in which the longitudinal direction of the hole-containing portion is 3 ° or more and 45 ° or less with respect to the short side direction of the viewing angle widening film. That is, in the viewing angle widening film 1 shown in FIG. 1, θ1a is 3 ° or more and 45 ° or less. θ1a is preferably 5 ° or more, more preferably 6 ° or more, particularly preferably 7 ° or more, preferably 20 ° or less, more preferably 15 ° or less. By setting the range of θ1a as described above, it is possible to eliminate the moire interference phenomenon.

The present invention also includes a mode in which the longitudinal direction of the hole-containing portion is 3 ° or more and 45 ° or less with respect to the long side direction of the viewing angle widening film. In this aspect, θ1b is 3 ° or more and 45 ° or less. θ1b is preferably 5 ° or more, more preferably 6 ° or more, particularly preferably 7 ° or more, preferably 20 ° or less, more preferably 15 ° or less. By setting the range of θ1b as described above, it is possible to eliminate the moire interference phenomenon.

The "longitudinal direction of the hole-containing portion" in the present invention will be described with reference to FIG. FIG. 2 is an enlarged schematic diagram schematically showing a hole-containing portion observed when the viewing angle widening film is observed in a plane. In FIG. 2, in order to describe the “longitudinal direction of the hole containing portion”, the vertical direction of the paper surface and the longitudinal direction of the hole containing portion are shown to be substantially parallel. In the figure, L is the length of the hole-containing portion in the longitudinal direction, L1 is the length from the center 20P of the hole-containing portion to 20A1 (0.4L), and L2 is the length from the center 20P of the hole-containing portion to 20A2 ( 0.4 L). In the present invention, the term "longitudinal direction of the hole-containing portion" means that the lengths of the hole-containing portion in the longitudinal direction are L, and the positions 20A1 and 20A2 having a longitudinal length of ± 0.4 L from the center 20P are connected. Say the direction. The hole-containing portion can be observed using, for example, an optical microscope or a digital microscope. The "longitudinal direction of the hole-containing portion" means, for example, the longitudinal direction of 80% or more of the hole-containing portion observed with an optical microscope, a digital microscope, etc. Can

ㆍ Because the hole-containing part contains holes, the light incident on the hole-containing part is scattered. In addition, the inclusion of pores causes the refractive index of the pore-containing portion to be different from that of the portion of the pore-containing layer where the pore-containing portion is not formed. As a result, the angle of the light scattering direction can be expanded. Without being bound to a particular theory, it is believed that the widening of the viewing angle is achieved by such light scattering over a wide range.

The holes contained in the hole containing portion may or may not penetrate in the thickness direction of the viewing angle widening film. In any case, since the hole-containing portion contains holes, the structure has a depth in the thickness direction of the viewing angle widening film. Each pore-containing portion usually has a large number of pores, but the structure of the pore-containing portion is not limited to this, and may be a single crack-shaped pore. The depth of the hole-containing portion may extend over the entire thickness of the hole-containing layer or may extend over only a part thereof.

The plurality of hole-containing portions may be provided substantially parallel to each other. The hole-containing portions being “substantially parallel” to each other may be at an angle of more than 0 ° with each other within a range where the effect of the present invention can be obtained. For example, the hole-containing portion may not have a perfect straight line but may have a partially folded shape, so that there are partially non-parallel portions and the angles formed by each other may be more than 0 °. Specifically, there may be a portion forming an angle of preferably within ± 40 °, more preferably within ± 30 °. Since the hole-containing portions that are “substantially parallel” to each other may have such an angular relationship, in the hole-containing layer, the plurality of hole-containing portions may have intersections with each other.

The individual hole-containing parts usually have a substantially linear shape. The shape of the hole-containing portion being “substantially linear” includes the case where the hole-containing portion has a fold within the range in which the effect of the present invention can be obtained.

Intervals P between adjacent hole-containing portions may be constant or random. For example, in the example shown in FIG. 1, the interval P between the adjacent hole-containing portions 20 is not constant but random. From the viewpoint of obtaining a high effect of widening the viewing angle, it is preferable that the interval P between the hole-containing portions is random.

The distance P between the adjacent hole-containing portions is not particularly limited, but it is preferable that the distance is narrow from the viewpoint of suppressing a phenomenon such as moire interference and obtaining good display screen quality. Specifically, the distance may be preferably 50 μm or less, more preferably 30 μm or less, and further preferably 5 μm or less. When the intervals are random, it is preferable that the maximum value of the intervals in the viewing angle widening film is equal to or less than the upper limit. The lower limit of the interval is not particularly limited, but may be 0.5 μm or more.

In a preferred embodiment, a part or all of the plurality of hole-containing portions included in the viewing angle widening film is made of craze. From the viewpoint of ease of forming the hole-containing portion, the hole-containing portion is preferably made of craze.

Craze refers to a substantially linear crack formed on the film. Crazes typically have fibrils formed between such fissures and voids formed therebetween as pores. Fibrils refer to fibers obtained by fibrillation of molecules constituting a resin.

FIG. 3 is an enlarged schematic diagram showing an example of the structure of craze. In FIG. 3, the craze 21 has a large number of elongated fibrils 211 and voids 212 existing therebetween. The fibrils 211 usually extend in a direction substantially orthogonal to the longitudinal direction of the craze as the hole-containing portion. The craze having such a structure can be formed by subjecting a film to craze processing. By cracking the film and applying pressure to the film, cracks can be formed in the film, and in the gaps between the cracks, the molecules that form the resin can be made into fibers and fibrils and voids between them can be formed. . Details of craze processing will be described later.

The fibril diameter is usually 5 nm to 50 nm, preferably 10 nm to 50 nm, more preferably 10 nm to 40 nm, and even more preferably 20 nm to 40 nm. The diameter of the void in the craze is usually 5 nm to 45 nm, preferably 10 nm to 30 nm. When the pore-containing portion is composed of a craze, the width of the craze is usually 20 nm to 800 nm, preferably 30 nm to 600 nm, more preferably 40 nm to 300 nm. The craze height is usually 0.3 μm to 50 μm, preferably 0.4 μm to 30 μm, and more preferably 0.5 μm to 20 μm. The diameter of the fibrils here, the diameter of the voids and the width of the craze, and the value of the craze height are average values, specifically, observing any three points where the craze is expressed with a scanning electron microscope, It can be determined by measuring the size of fibrils and voids.

[3. Structure of viewing angle widening film)
The viewing angle widening film of the present invention may have a hole-containing portion on both surfaces, or may have a hole-containing portion on only one of the surfaces. The viewing angle widening film of the present invention may have a single-layer structure composed of one layer or a multi-layer structure composed of two or more layers.

When the viewing angle widening film has a single-layer structure, the hole-containing portion may be formed on at least one surface of the layer. When the viewing angle widening film has a single-layer structure, the viewing angle widening film is preferably a resin film (resin layer).

When the viewing angle widening film has a multi-layer structure, the pore-containing portion may be formed in a plurality of layers or may be formed in only one layer. When the viewing angle widening film has a multilayer structure, it may have two or more resin layers, or may be a combination of a resin layer and a layer made of a material other than resin.
The viewing angle widening film of the present invention preferably has two or more resin layers, and at least one of the resin layers is a layer containing a hole-containing portion.

The thickness of the layer containing the pore-containing portion (also referred to as “pore-containing layer”) is preferably 0.2 μm or more, more preferably 0.5 μm or more, preferably 20 μm or less, more preferably 10 μm or less. When the viewing angle widening film includes two or more hole-containing layers, the total thickness of the hole-containing layers is preferably within this range. When the thickness of the pore-containing layer is within such a range, the pore-containing layer having the effect of the present invention can be easily constructed.

When the layer including the hole-containing portion has optical anisotropy, its refractive index can be (nx + ny) / 2.

[4. Materials for viewing angle widening film]
In the present invention, the hole-containing portion is preferably formed in the resin layer. The resin forming the resin layer including the pore-containing portion preferably contains an alicyclic structure-containing polymer and a hydrocarbon compound. Hereinafter, an example of the material forming the resin layer including the hole-containing portion will be described, but the present invention is not limited to this aspect, and other materials can be used.

[4.1. Alicyclic structure-containing polymer]
In the present invention, the resin constituting the layer containing the pore-containing portion contains a polymer having an alicyclic structure, which is a polymer having a low water absorption rate, and thus has a good visual field even after storage in a high humidity environment. The angular expansion characteristic can be maintained.

Examples of the alicyclic structure-containing polymer include (1) norbornene-based polymer, (2) monocyclic cycloolefin-based polymer, (3) cyclic conjugated diene-based polymer, (4) vinyl alicyclic carbonization. Examples thereof include hydrogen-based polymers and hydrides of (1) to (4). Among these, the norbornene-based polymer and its hydride are preferable from the viewpoint of heat resistance, mechanical strength and the like.

Examples of the norbornene-based polymer include ring-opening polymers of norbornene monomers, ring-opening copolymers of norbornene monomers with other monomers capable of ring-opening copolymerization, and hydrides thereof; addition polymers of norbornene monomers, Examples thereof include addition copolymers of the norbornene monomer and other copolymerizable monomers. Among these, a hydride of a ring-opening polymer of a norbornene monomer and a hydride of a ring-opening copolymer of a norbornene monomer and another monomer capable of ring-opening copolymerization are particularly preferable from the viewpoint of transparency.

The polystyrene-equivalent or polyisoprene-equivalent weight average molecular weight of the alicyclic structure-containing polymer measured by gel permeation chromatography is usually 5,000 or more, preferably 10,000 or more, and more preferably 15,000 or more. And is usually 50,000 or less, preferably 45,000 or less, more preferably 40,000 or less.

[4.1.1. Hydrogenated block copolymer [G]]
As an example of the alicyclic structure-containing polymer, two or more polymer blocks [D] having a cyclic hydrocarbon group-containing compound hydride unit [I] and a chain hydrocarbon compound hydride unit [II] ] Or a hydrogenated block copolymer [G] containing one or more polymer blocks [E] having a combination of units [I] and units [II].

[Cyclic Hydrocarbon Group-Containing Compound Hydride Unit [I]]
The cyclic hydrocarbon group-containing compound hydride unit [I] is obtained by polymerizing a cyclic hydrocarbon group-containing compound, and further, if the unit obtained by such polymerization has an unsaturated bond, the unsaturated bond is formed. It is a structural unit having a structure obtained by hydrogenation. However, the cyclic hydride group-containing compound hydride unit [I] includes a unit obtained by any production method as long as it has the structure.

The cyclic hydride group-containing compound hydride unit [I] is preferably a structural unit obtained by polymerization of an aromatic vinyl compound. More specifically, it is a structural unit (aromatic vinyl compound hydride unit [I]) having a structure obtained by polymerizing an aromatic vinyl compound and hydrogenating its unsaturated bond. However, the aromatic vinyl compound hydride unit [I] includes a unit obtained by any manufacturing method as long as it has the structure.
Similarly, in the present application, for example, a structural unit having a structure obtained by polymerizing styrene and hydrogenating its unsaturated bond may be referred to as a styrene hydride unit. The styrene hydride unit also includes a unit obtained by any production method as long as it has the structure.
Examples of the aromatic vinyl compound hydride unit [I] include structural units represented by the following structural formula (1).

In Structural Formula (1), R ^c represents an alicyclic hydrocarbon group. Examples of R ^c include cyclohexyl groups such as cyclohexyl groups; decahydronaphthyl groups and the like.

In the structural formula (1), R ¹ , R ² and R ³ are each independently a hydrogen atom, a chain hydrocarbon group, a halogen atom, an alkoxy group, a hydroxyl group, an ester group, a cyano group, an amide group or an imide group. Represents a chain hydrocarbon group substituted with a silyl group or a polar group (a halogen atom, an alkoxy group, a hydroxyl group, an ester group, a cyano group, an amide group, an imide group, or a silyl group). Among them, R ¹ , R ² and R ³ are preferably a hydrogen atom and a chain hydrocarbon group having 1 to 6 carbon atoms from the viewpoint of heat resistance, low birefringence and mechanical strength. The chain hydrocarbon group is preferably a saturated hydrocarbon group, more preferably an alkyl group.

Specific preferred examples of the aromatic vinyl compound hydride unit [I] include structural units represented by the following formula (1-1). The structural unit represented by the formula (1-1) is a styrene hydride unit.

In the exemplified hydride unit [I] of the cyclic hydrocarbon group-containing compound, those having stereoisomers can be used in any stereoisomers. As the cyclic hydrocarbon group-containing compound hydride unit [I], only one type may be used, or two or more types may be used in combination at an arbitrary ratio.

[Chain hydrocarbon compound hydride unit [II]]
The chain hydrocarbon compound hydride unit [II] is obtained by polymerizing a chain hydrocarbon compound and further hydrogenating the unsaturated bond if the unit obtained by such polymerization has an unsaturated bond. Is a structural unit having a structure described below. However, the chain hydrocarbon compound hydride unit [II] includes a unit obtained by any production method as long as it has the structure.

The chain hydrocarbon compound hydride unit [II] is preferably a structural unit obtained by polymerization of a diene compound. More specifically, a structural unit having a structure obtained by polymerizing a diene compound and further hydrogenating the unsaturated bond if the unit obtained by such polymerization has an unsaturated bond (diene compound hydrogen Compound unit [II]). However, the diene compound hydride unit [II] includes a unit obtained by any manufacturing method as long as it has the structure.
Similarly, in the present application, a structural unit having a structure obtained by polymerizing isoprene and hydrogenating its unsaturated bond may be referred to as an isoprene hydride unit. The isoprene hydride unit also includes a unit obtained by any production method as long as it has the structure.

The diene compound hydride unit [II] is preferably a structural unit obtained by polymerization of a conjugated diene compound. More specifically, it preferably has a structure obtained by polymerizing a conjugated diene compound such as a chain conjugated diene compound and hydrogenating the unsaturated bond. Examples thereof include a structural unit represented by the following structural formula (2) and a structural unit represented by the structural formula (3).

In the structural formula (2), R ⁴ to R ⁹ are each independently a hydrogen atom, a chain hydrocarbon group, a halogen atom, an alkoxy group, a hydroxyl group, an ester group, a cyano group, an amide group, an imide group, a silyl group. Or represents a chain hydrocarbon group substituted with a polar group (halogen atom, alkoxy group, hydroxyl group, ester group, cyano group, amide group, imide group, or silyl group). Among them, R ⁴ to R ⁹ are preferably a hydrogen atom and a chain hydrocarbon group having 1 to 6 carbon atoms from the viewpoint of heat resistance, low birefringence, mechanical strength and the like. The chain hydrocarbon group is preferably a saturated hydrocarbon group, more preferably an alkyl group.

In the structural formula (3), R ¹⁰ to R ¹⁵ are each independently a hydrogen atom, a chain hydrocarbon group, a halogen atom, an alkoxy group, a hydroxyl group, an ester group, a cyano group, an amide group, an imide group or a silyl group. Or represents a chain hydrocarbon group substituted with a polar group (halogen atom, alkoxy group, hydroxyl group, ester group, cyano group, amide group, imide group, or silyl group). Among them, R ¹⁰ to R ¹⁵ are preferably a hydrogen atom and a chain hydrocarbon group having 1 to 6 carbon atoms from the viewpoint of heat resistance, low birefringence, mechanical strength and the like. The chain hydrocarbon group is preferably a saturated hydrocarbon group, more preferably an alkyl group.

Specific preferred examples of the diene compound hydride unit [II] include structural units represented by the following formulas (2-1) to (2-3). The structural units represented by the formulas (2-1) to (2-3) are isoprene hydride units.

Any of the stereoisomers of the chain hydrocarbon compound hydride unit [II] having stereoisomers can be used. As the chain hydrocarbon compound hydride unit [II], only one kind may be used, or two or more kinds may be used in combination at an arbitrary ratio.

[4.1.2. Details of Hydrogenated Block Copolymer [G]]
The hydrogenated block copolymer [G] preferably has a triblock molecular structure having one block [E] per molecule and two blocks [D] connected to both ends thereof per molecule. That is, the hydrogenated block copolymer [G] has one block [E] per molecule; and a cyclic hydride group-containing compound hydride unit [I] linked to one end of the block [E]. One block [D1] per molecule; one block [D2] per molecule having a cyclic hydride group-containing compound hydride unit [I] linked to the other end of the block [E]; It is preferably a triblock copolymer containing.

In the hydrogenated block copolymer [G] as the above-mentioned triblock copolymer, from the viewpoint of easily obtaining the pore-containing layer having preferable characteristics, the total of the block [D1] and the block [D2] and the block [D1] It is preferable that the weight ratio (D1 + D2) / E with E] falls within a specific range. Specifically, the weight ratio (D1 + D2) / E is preferably 45/55 or more, more preferably 50/50 or more, preferably 89/11 or less, more preferably 86/14 or less.

In the hydrogenated block copolymer [G] as the above-mentioned triblock copolymer, the weight ratio of the block [D1] and the block [D2] is preferably from the viewpoint of easily obtaining a pore-containing layer having preferable properties. It is preferable that D1 / D2 falls within a specific range. Specifically, the weight ratio D1 / D2 is preferably 1 or more, more preferably 3 or more, particularly preferably 5 or more, preferably 15 or less, more preferably 14 or less, and particularly preferably 13 or less.

The weight average molecular weight Mw of the hydrogenated block copolymer [G] is preferably 50,000 or more, more preferably 55,000 or more, particularly preferably 60,000 or more, preferably 85,000 or less, more preferably 80,000 or less, particularly preferably 75,000. It is the following. When the weight average molecular weight Mw is within the above range, it is possible to easily obtain a resin layer having a hole-containing portion having preferable properties.

The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the hydrogenated block copolymer [G] is preferably 2.0 or less, more preferably 1.7 or less, and particularly preferably 1.5. It is below, preferably 1.0 or above. When the weight average molecular weight Mw is within the above range, the polymer viscosity can be lowered and the moldability can be enhanced.

The weight average molecular weight Mw and the number average molecular weight Mn of the hydrogenated block copolymer [G] can be measured as polystyrene equivalent values by gel permeation chromatography using tetrahydrofuran as a solvent.

It is preferable that the block [D1] and the block [D2] each independently include only the cyclic hydrocarbon group-containing compound hydride unit [I], but other than the cyclic hydrocarbon group-containing compound hydride unit [I]. Can include any unit. Examples of the optional structural unit include structural units based on vinyl compounds other than the cyclic hydrocarbon group-containing compound hydride unit [I]. The content of any structural unit in the block [D] is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 1% by weight or less.

The block [E] consists only of a chain hydrocarbon compound hydride unit [II], or consists only of a cyclic hydrocarbon group-containing compound hydride unit [I] and a chain hydrocarbon compound hydride unit [II]. However, it may contain any unit other than the units [I] and [II]. Examples of the optional structural unit include structural units based on vinyl compounds other than the units [I] and [II]. The content of any structural unit in the block [E] is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 1% by weight or less.

When the block [E] contains a cyclic hydride group-containing compound hydride unit [I] and a chain hydrocarbon compound hydride unit [II], the units [I] and [II] in the block [E] The weight ratio [I] / [II] is preferably 0.1 or more, more preferably 0.2 or more, particularly preferably 0.3 or more, preferably 1.5 or less, more preferably 1.4 or less. It is particularly preferably 1.3 or less.
The weight ratio [I] / [II] of the units [I] and [II] in the molecule of the hydrogenated block copolymer [G] is preferably 70/30 or more, more preferably 72/28 or more, It is particularly preferably 74/26 or more, preferably 89/11 or less, more preferably 85/15 or less, and particularly preferably 83/17 or less. When the ratio of the units [I] and [II] is within the above range, it is possible to easily obtain a pore-containing layer having preferable properties.

The method for producing the hydrogenated block copolymer [G] is not particularly limited, and any production method can be adopted. For the hydrogenated block copolymer [G], for example, a monomer corresponding to the cyclic hydrocarbon group-containing compound hydride unit [I] and the chain hydrocarbon compound hydride unit [II] is prepared, and these are prepared. It can be produced by polymerizing and polymerizing the obtained polymer [F]. Specific production can be carried out by appropriately combining, for example, the method described in WO 2016/152871 and other known methods. The hydrogenation rate in the hydrogenation reaction is usually 90% or more, preferably 95% or more, more preferably 97% or more. By increasing the hydrogenation rate, low birefringence and thermal stability of the hydrogenated block copolymer [G] can be improved. The hydrogenation rate can be measured by ¹ H-NMR.

[4.2. Hydrocarbon compound]
The resin forming the pore-containing layer preferably contains a hydrocarbon compound other than the alicyclic structure-containing polymer described above. In the present invention, the resin forming the hole-containing layer contains a hydrocarbon compound having a number average molecular weight of 200 to 1500, whereby holes capable of achieving the viewing angle widening property can be developed.

The number average molecular weight of the hydrocarbon compound is 200 to 1500. The number average molecular weight of the hydrocarbon compound is preferably 300 or more, more preferably 500 or more, preferably 1400 or less, more preferably 1300 or less. By setting the number average molecular weight of the hydrocarbon compound to the lower limit value or more, the effect that the hydrocarbon compound does not bleed out is obtained, and by setting the number average molecular weight to the upper limit value or less, the viewing angle expansion property is improved. The holes to be formed can be easily expressed.

Examples of hydrocarbon compounds include petroleum resins and plant-based hydrocarbon resins. In the present application, the hydrocarbon compound may be not only a compound consisting of carbon atoms and hydrogen atoms but also a compound containing a small amount of oxygen atoms. For example, it may be a compound having 1 or less oxygen atom with respect to 8 carbon atoms.

The petroleum resin means a resin obtained by polymerizing diolefins and monoolefins in a fraction of a cracked oil produced as a by-product during the production of ethylene by steam cracking of petroleum by a known method.
Examples of petroleum resins are C5-based petroleum resins (wherein the above-mentioned fraction is derived from C5 fractions such as isoprene, 1,3-pentadiene, cyclopentene, cyclopentadiene, dicyclopentadiene (DCPD)), C9-based petroleum resins. (The above-mentioned fraction is made from C9 fraction such as vinyltoluene, α-methylstyrene, indene, alkylindene, etc.), C5 and C9 copolymerized petroleum resin, hydrogenated C5 petroleum resin, hydrogenated C9 Petroleum resin, petroleum resin which is a copolymer of DCPD and other compounds and its hydride (hydrogenated DCPD petroleum resin) (for example, copolymer of DCPD and C9 fraction, copolymer of DCPD and aromatic compound) Polymers and their hydrides).

Specific examples of the petroleum resin include "Arcon (registered trademark)" manufactured by Arakawa Chemical Industry Co., Ltd., "Petocol (registered trademark)" manufactured by Tosoh Corporation, and Idemitsu Petrochemical Co., Ltd. Examples include the product name "I-MARV" and the T-REZ H series manufactured by JXTG Energy Co., Ltd.

Examples of the plant-based hydrocarbon resin include rosin acid, dimer acid (difunctional C36 compound, etc.), and various terpene resins (pinene resin, next terpene resin, aromatic modified terpene resin, terpene phenol resin, hydrogenated terpene resin). ) Is mentioned.
More specific examples of the plant-based hydrocarbon resin include rosin derivatives manufactured by Arakawa Chemical Industry Co., Ltd., hydrogenated dimer acid manufactured by Croda Japan Co., Ltd., and terpene resins manufactured by Yasuhara Chemical Co., Ltd. .

The resin forming the pore-containing layer may contain one kind or two or more kinds of hydrocarbon compounds. The hydrocarbon compound is preferably hydrogenated petroleum resin, and more preferably one or more selected from hydrogenated C9 petroleum resin and hydrogenated DCPD petroleum resin.

The hydrocarbon compound preferably has a softening point of 90 ° C or higher and 150 ° C or lower. The softening point of the hydrocarbon compound is more preferably 100 ° C. or higher, further preferably 110 ° C. or higher, and more preferably 145 ° C. or lower. By setting the softening point of the hydrocarbon compound to the upper limit or lower, in the viewing angle widening film, it is possible to develop pores that make the viewing angle widening property better, and by setting the softening point to the lower limit or higher. Also, good viewing angle widening characteristics can be maintained even after storage in a high temperature environment. The softening point can be measured by the ring and ball method specified by JIS K2531.

[4.2.1. Ratio of hydrocarbon compound]
The proportion of the hydrocarbon compound in the resin constituting the pore-containing layer is preferably 0.5% by weight or more, more preferably 5% by weight or more, based on the total amount of the alicyclic structure-containing polymer and the hydrocarbon compound. %, Preferably 40% by weight or less, more preferably 35% by weight or less. By setting the hydrocarbon compound to the lower limit or more, it is possible to easily develop pores that make the viewing angle widening property good, and by setting the hydrocarbon compound to the upper limit or less, it is stored in a high humidity environment. Even after this, good viewing angle widening characteristics can be maintained.

[4.3. Characteristics of resin constituting resin layer including pore-containing portion]
The glass transition temperature (Tg) of the resin forming the resin layer including the pore-containing portion is preferably 115 ° C. or higher, more preferably 118 ° C. or higher, still more preferably 120 ° C. or higher. The upper limit of the glass transition temperature is not particularly limited, but is preferably 160 ° C or lower, more preferably 150 ° C or lower. By setting the Tg of the resin forming the resin layer including the hole-containing portion to the lower limit value or more, it is possible to maintain good viewing angle widening characteristics even after storage in a high temperature environment.

The resin that constitutes the resin layer including the pore-containing portion may optionally contain an optional component other than the alicyclic structure-containing polymer and the hydrocarbon compound. Examples of optional components include ultraviolet absorbers, antioxidants, heat stabilizers, light stabilizers, antistatic agents, dispersants, chlorine scavengers, flame retardants, crystallization nucleating agents, strengthening agents, antiblocking agents, antifogging agents. Agents, release agents, pigments, organic or inorganic fillers, neutralizing agents, lubricants, decomposing agents, metal deactivators, antifouling agents, and antibacterial agents.
The resin forming the resin layer including the hole-containing portion preferably contains an ultraviolet absorber.

Examples of ultraviolet absorbers are oxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, acrylonitrile ultraviolet absorbers, triazine compounds, nickel complex salt compounds, And inorganic powders. Examples of suitable UV absorbers are 2,2'-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- ( 2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2,4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone and 2,2 ', 4,4'-tetrahydroxybenzophenone can be mentioned. A particularly suitable example is 2,2'-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol).

When the resin forming the resin layer including the pore-containing portion contains an ultraviolet absorber, the content of the ultraviolet absorber is preferably 0.5 to 5% by weight per 100% by weight of the resin.

[5. Resin layer other than resin layer including hole-containing portion]
The viewing angle widening film of the present invention may include only the resin layer including the hole-containing portion, or may include the resin layer including the hole-containing portion and any resin layer that does not include the hole-containing portion in combination. . A useful viewing angle widening film can be formed by combining a resin layer containing a hole-containing portion with a resin layer other than the resin layer.

An example of such an optional resin layer is a reinforcing layer having higher strength than the resin layer including the hole-containing portion. The resin layer including the hole-containing portion may have low strength by containing holes. However, by providing such a reinforcing layer, a viewing angle widening film having both optical performance and strength can be obtained.

Another example of the arbitrary resin layer is a protective layer provided on one or both of the front surface and the back surface of the resin layer including the hole-containing portion. The resin layer containing the hole-containing portion may have irregularities on its surface by containing pores. By providing such a protective layer, a viewing angle widening film having both optical performance and surface smoothness is obtained. be able to. The protective layer may further have the function as the reinforcing layer described above. For example, the viewing angle widening film of the present invention has a layer structure of 2 layers and 3 layers of skin layer / core layer / skin layer, the core layer is a hole-containing layer, and the skin layer is a reinforcing layer and / or a protective layer. Can function as a layer.

Another example of the optional resin layer is an easy-adhesion layer for improving the adhesiveness between the viewing angle widening film and other members.

When the viewing angle widening film of the present invention has a resin layer other than the resin layer including the hole-containing portion, the resin forming such a layer is not particularly limited, and any material having desired characteristics can be appropriately selected. . For example, as the resin constituting the reinforcing layer and the protective layer, as a polymer, a resin containing a polymer selected from polystyrene, polypropylene, polyethylene, polyester, polyamide, polyvinylidene fluoride, and an alicyclic structure-containing polymer can be mentioned. To be As the resin constituting the reinforcing layer and the protective layer, those having desired characteristics can be appropriately selected from the examples of these resins.

The thickness of the viewing angle widening film is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 20 μm or more. The upper limit is not particularly limited, but is preferably 100 μm or less, more preferably 70 μm or less, and further preferably 40 μm or less.

[6. Shape and physical properties of viewing angle widening film)
The viewing angle widening film of the present invention may be a long film or a single film. Usually, the viewing angle widening film is manufactured as a long film from the viewpoint of increasing manufacturing efficiency. Further, in the case of manufacturing a single-viewing angle expansion film, a single-viewing angle expansion film can be manufactured by cutting out a long viewing angle expansion film into a desired shape.

The viewing angle widening film of the present invention may be a film having small optical anisotropy and being substantially optically isotropic, or may be an optically anisotropic film. When the viewing angle widening film is optically anisotropic, such anisotropy may be due to the hole-containing layer, or may be due to a layer other than the hole-containing layer, It may be due to both of them.

When the viewing angle widening film of the present invention is an optically anisotropic film, its in-plane retardation Re is preferably 360 nm or less, more preferably 330 nm or less, still more preferably 300 nm or less. The lower limit is not particularly limited, but is preferably 10 nm or more, more preferably 20 nm or more, and further preferably 30 nm or more. The retardation Rth in the thickness direction is preferably 400 nm or less, more preferably 350 nm or less, and further preferably 300 nm or less. The lower limit is not particularly limited, but is preferably 10 nm or more, more preferably 20 nm or more, and further preferably 30 nm or more.

The total light transmittance of the viewing angle widening film is preferably 70% or more, more preferably 80% or more. The light transmittance can be measured using a spectrophotometer (UV-Vis near-infrared spectrophotometer "V-570" manufactured by JASCO Corporation) according to JIS K0115.

[7. Manufacturing method of viewing angle widening film]
The method for producing a viewing angle widening film of the present invention comprises the step 1 of forming a hole-containing portion on at least one surface of the first film, and stretching the first film subjected to the step 1 to obtain the hole-containing portion. And step 2 of expanding the hole diameter of.

[7.1. Process 1]
Step 1 is a step of forming a hole containing portion on at least one surface of the first film. By carrying out step 1, it is possible to form a hole-containing portion in the first film which is a material of the viewing angle widening film of the present invention. The first film is a film used for forming the hole-containing portion, and may be referred to as a "material film".

[7.1.1. Production of first film (material film)]
The layer structure of the material film is not particularly limited, and may be a layer structure suitable for the desired layer structure of the viewing angle widening film. For example, it may have a layer structure including a resin layer including a hole-containing portion and a layer other than the resin layer. More specifically, by combining a layer that can be a layer containing pore-containing portions by craze processing and a layer in which craze does not occur even by such craze processing, a resin layer containing pore-containing portions, and a resin layer other than that. A material film for obtaining a viewing angle widening film having

Examples of the material film manufacturing method include an injection molding method, an extrusion molding method, a press molding method, an inflation molding method, a blow molding method, a calender molding method, a cast molding method, and a compression molding method.

The conditions such as the temperature of the molten resin when manufacturing the material film can be appropriately changed according to the type of the material film, and can be performed under known conditions.

When the material film has two or more resin layers, examples of the method for producing the material film include coextrusion T-die method, coextrusion inflation method, coextrusion lamination method, dry lamination, cocasting method, and coating molding. There is a law.

When the material film has two or more resin layers, it is preferable to manufacture the material film by a coating molding method. In the case of the coating molding method, for example, a resin which is a material of one layer (layer A) is molded into a film, and the resin which is a material of layers other than the layer A is dissolved in a solvent in the film-shaped layer A. A material film can be obtained by applying the coating liquid thus obtained and drying.

The material film may be an unstretched unstretched film or a stretched stretched film. Further, a film having a multilayer structure obtained by laminating a stretched film formed of a certain material and an unstretched film formed of the same material may be used as the material film.

[7.1.2. Formation of hole-containing part]
After the first film (material film) is manufactured, the hole-containing portion is formed on the surface of the material film, whereby the first film including the hole-containing portion is obtained.
Examples of a specific method for forming the hole-containing portion include craze processing. By performing craze processing, it is possible to efficiently produce a viewing angle widening film in which the hole-containing portion is made of craze.

A specific example of craze processing will be described with reference to FIGS. 4 and 5. FIG. 4 is a perspective view schematically showing an example of the craze processing apparatus, and FIG. 5 is a side view schematically showing the vicinity of the blade of FIG. 4 in an enlarged manner. In FIG. 5, the device is observed from the TD direction.

In the example of FIG. 4, the craze processing apparatus 100 includes a payout roll 41, transport rolls 42 and 43, and a blade 30. The blade 30 includes an edge 30E extending in a direction parallel to the TD direction.
In the operation of the craze processing apparatus 100, the first film 10 transported in the direction of the arrow A11 from the payout roll 41 is supported by the transport rolls 42 and 43 while being urged against the edge 30E of the blade 30. Be transported. Thereby, pressure can be applied to the first film 10. As a result, the surface of the first film 10 is deformed by pressure, the hole-containing portion 20 extending in the direction substantially parallel to the TD direction is formed, and the first film 11 including the hole-containing portion is obtained. (See Figure 6). In the first film 11 including the hole-containing portion, the longitudinal direction of the hole-containing portion is parallel to the TD direction (XX line direction).

In craze processing, the angle at which the blade 30 contacts the first film 10 can be appropriately adjusted to the angle at which a desired craze is formed. In the example of FIGS. 4 and 5, the angle is represented as an angle θx formed by the center line 30C of the blade 30 observed from the extension direction of the edge 30E and the downstream surface of the first film 10. The angle θx is preferably 10 ° to 60 °, more preferably 15 ° to 50 °, even more preferably 20 ° to 40 °.

The tension of the material film when the blade is pressed against the first film can be appropriately adjusted to a value at which a desired craze is formed. The tension is preferably 100 N / m to 1000 N / m, more preferably 300 N / m to 800 N / m.

When a material film having two or more resin layers is used as the first film and the material film is subjected to craze processing, craze may occur in all of the two or more resin layers, Crazing may occur only in the resin layer. Further, in the case where craze occurs in only a part of the resin layers, craze may occur in the outermost surface layer and craze may occur in the inner layer. For example, when a material film consisting of a core layer made of a material having a relatively small tensile elongation and brittleness and skin layers made of a relatively flexible material on the front and back surfaces thereof is subjected to craze processing, the craze is applied only to the core layer. Can occur. Such a film can also be used as a material for the viewing angle widening film of the present invention.

[7.2. Process 2]
Step 2 is a step of stretching the first film subjected to Step 1 to expand the pore diameter of the pore-containing portion. By carrying out the step 2, the pore diameter of the pore-containing portion (pore diameter) is expanded, whereby a viewing angle widening film exhibiting a viewing angle widening effect can be obtained.

The method for stretching the first film including the pore-containing portion obtained by performing step 1 is not particularly limited, but diagonal stretching is preferable. A specific example of a suitable stretching method will be described with reference to FIG. FIG. 6 is a plan view schematically showing the first film 11 having a hole-containing portion.

From the viewpoint of excellent production efficiency and easy control of the longitudinal direction of the hole-containing portion, as shown in FIG. 6, the stretching of the first film 11 including the hole-containing portion is performed in the short side direction (X- It is preferable to perform stretching (oblique stretching) at an angle indicated by θA with respect to the X-ray direction). When the stretching angle θA is 3 ° or more and 45 °, it is possible to obtain a viewing angle widening film in which the angle θ1a formed by the longitudinal direction of the hole-containing portion and the short side direction of the film is 3 ° or more and 45 °.

The viewing angle widening film in which the angle θ1b formed by the longitudinal direction of the hole-containing portion and the long-side direction of the film is 3 ° or more and 45 ° or less is a hole-containing portion with respect to the TD direction (XX line direction) shown in FIG. Of the first resin film 11 formed by stretching the first film 11 in which the longitudinal directions of the first resin film 11 are parallel to each other in the direction indicated by θA with respect to the short side direction (XX line direction) of the film. It can be manufactured by cutting the stretched first resin film into a rectangular shape having a long side in the direction.

The stretching can be performed using a known stretching device. Examples of the stretching device include a longitudinal uniaxial stretching machine, a tenter stretching machine, a bubble stretching machine, and a roller stretching machine.

In step 1, when the hole-containing portion is formed in the one or more resin layers of the first film including the one or more resin layers, the stretching temperature of the first film 11 including the hole-containing portion is preferably It is (Tg-30 ° C) or higher, more preferably (Tg-10 ° C) or higher, preferably Tg or lower, more preferably (Tg-5) ° C or lower. Here, "Tg" represents the glass transition temperature of the resin forming the resin layer in which the hole-containing portion is formed. By setting the stretching temperature at the upper limit or less, the effect of expanding the pore diameter of the pore-containing portion by stretching can be made more effective.

The stretch ratio is preferably 1.05 or more, more preferably 1.1 or more, preferably 2.0 or less, more preferably 1.5 or less. When stretching is performed in a plurality of different directions such as biaxial stretching, it is preferable that the total stretching ratio represented by the product of the stretching ratios in each stretching direction falls within the above range.

In the above-mentioned manufacturing method, in step 1, the hole-containing portion is formed by a blade provided with an edge 30E extending in a direction parallel to the TD direction, but the angle of the blade is, for example, the short side direction or the long side of the first film. The hole-containing portion may be formed by arranging at a predetermined angle with respect to the side direction. When the first film including the hole-containing portion is produced by such a method, the first film including the hole-containing portion may be the viewing angle widening film, but the first film including the hole-containing portion may be used. Performing the step of stretching the film to expand the pore diameter (step 2) is preferable because a viewing angle widening film in which the pore diameter of the pore-containing portion is expanded can be obtained.

[8. Use of viewing angle widening film: polarizing plate)
The viewing angle widening film of the present invention is a film for widening the viewing angle. Specifically, it can be used for widening the viewing angle of a display device such as a liquid crystal display device. However, the function of the viewing angle widening film of the present invention is not limited to this. For example, the viewing angle widening film of the present invention may exhibit not only the function as the viewing angle widening film but also the other functions. Examples of functions other than the viewing angle widening film include a function as a protective film, a function as a retardation film, and a function as an optical compensation film. In particular, as will be described below, it can be preferably used as a polarizing plate that also exhibits a function as a polarizing plate protective film.

The polarizing plate of the present invention includes the viewing angle widening film of the present invention and a polarizer. In the polarizing plate of the present invention, the viewing angle widening film can also function as a polarizing plate protective film. Such a polarizing plate can be manufactured by, for example, laminating a polarizer and a viewing angle widening film. In the polarizing plate of the present invention, the polarizer and the viewing angle widening film may be directly attached without an adhesive layer, or may be attached via an adhesive layer formed of an adhesive. . Furthermore, another protective film may be interposed between the polarizer and the viewing angle widening film.

When the viewing angle widening film has a hole-containing portion only on one surface side thereof, the surface may be located on the polarizer side or on the opposite side to the polarizer.

The polarizing plate of the present invention may be provided with a viewing angle widening film on only one surface of the polarizer, or may be provided with a viewing angle widening film on both surfaces. When the viewing angle expansion film is provided on only one surface of the polarizer, the polarizing plate may be provided with any film other than the viewing angle expansion film that can function as a protective film on the other surface of the polarizer.

In the polarizing plate of the present invention, the visual field expanding film can be in direct contact with the polarizer. Alternatively, the polarizing plate of the present invention may further have another layer interposed between the visual field widening film and the polarizer. When the field-of-view magnifying film is in contact with the polarizer directly or via only the adhesive layer, the field-of-view magnifying film can function as a protective film for protecting the polarizer in the polarizing plate.
On the other hand, the polarizing plate and the liquid crystal display device of the present invention can be configured by simply adding a visual field expanding film to the existing liquid crystal display device. Specifically, by placing a visual field expansion film on the display surface of a liquid crystal display device having various constituent elements such as a protective film on the visual recognition side further than the visual recognition side polarizer, the visual recognition side polarizer and the visual field expansion A polarizing plate and a liquid crystal display device of the present invention can be constructed by combining with a film.

When the polarizing plate of the present invention is used in a VA mode liquid crystal display device described later, the angle formed by the longitudinal direction of the hole-containing portion and the direction perpendicular to the absorption axis of the polarizer is 3 ° or more and 45 ° or less. preferable. Accordingly, the viewing angle of the VA mode liquid crystal display device can be expanded.

When the polarizing plate of the present invention is used in a TN mode liquid crystal display device to be described later, when the display screen of the liquid crystal display device is viewed from an oblique direction, the azimuth angle at which gradation is inverted and the longitudinal direction of the hole-containing portion are formed. It is preferable that the angle is 90 ° + θ1 and θ1 is 3 ° or more and 45 ° or less. As a result, the viewing angle of the TN mode liquid crystal display device can be expanded.

The polarizer can be produced, for example, by adsorbing iodine or a dichroic dye on a polyvinyl alcohol film and then uniaxially stretching it in a boric acid bath. Alternatively, for example, it can be produced by adsorbing iodine or a dichroic dye on a polyvinyl alcohol film, stretching the film, and further modifying a part of the polyvinyl alcohol unit in the molecular chain into a polyvinylene unit. Further, as the polarizer, for example, a polarizer having a function of separating polarized light into reflected light and transmitted light, such as a grid polarizer, a multilayer polarizer, and a cholesteric liquid crystal polarizer may be used. Among these, a polarizer containing polyvinyl alcohol is preferable. The polarization degree of the polarizer is preferably 98% or more, more preferably 99% or more. The average thickness of the polarizer is preferably 5 μm to 80 μm.

As the adhesive for bonding the polarizer and the viewing angle widening film, any optically transparent adhesive may be used. Examples of adhesives include water-based adhesives, solvent-based adhesives, two-component curable adhesives, ultraviolet curable adhesives, and pressure-sensitive adhesives. Among these, a water-based adhesive is preferable, and a polyvinyl alcohol-based water-based adhesive is particularly preferable. Further, the adhesive may be used alone or in combination of two or more kinds at an arbitrary ratio.

The average thickness of the adhesive layer is preferably 0.05 μm or more, more preferably 0.1 μm or more, preferably 5 μm or less, more preferably 1 μm or less.

There is no limitation on the method of bonding the viewing angle widening film and the polarizer. As a preferred example of the laminating method, after applying an adhesive to one surface of the polarizer as needed, the polarizer and the viewing angle widening film are laminated using a roll laminator, and dried if necessary. The method to do is mentioned. The drying time and the drying temperature are appropriately selected according to the type of adhesive.

[9. Liquid crystal display device)
The viewing angle widening film of the present invention and the polarizing plate of the present invention can be used in a liquid crystal display device. A known liquid crystal cell such as a TN (Twisted Nematic) mode, a VA (Virtual Alignment) mode, and an IPS (In-Plane Switching) mode can be used as a liquid crystal cell constituting the liquid crystal display device. Of these, the TN mode and the VA mode are preferable from the viewpoint of effectively expanding the viewing angle.

[9.1. TN mode liquid crystal display device]
The viewing angle widening film of the present invention or the polarizing plate of the present invention is preferably used in a TN mode liquid crystal display device.

The TN mode liquid crystal display device of the present invention is provided with the polarizing plate of the present invention and the TN mode liquid crystal cell in this order from the viewer side, and the viewing side of the polarizing plate is the viewing angle widening film side. When the display screen of the liquid crystal display device is viewed in an oblique direction, the azimuth angle that is gradation-reversed and the longitudinal direction of the hole-containing portion are 90 ° + θ1 (θ1 is 3 ° or more and 45 ° or less). is there. Here, the azimuth angle at which the gradation is reversed means that the polarizing plate of the present invention was replaced with a polarizing plate having the same structure as the polarizing plate of the present invention except that the viewing angle widening film of the present invention was not provided. This is the azimuth angle at which the gradation is reversed.

TN-mode liquid crystal display devices usually include a polarizing plate and a light source on the side opposite to the viewing side of the TN-mode liquid crystal cell. As the polarizing plate arranged on the side opposite to the viewing side, the polarizing plate of the present invention may be used, or a polarizing plate other than the polarizing plate of the present invention such as a known polarizing plate may be used. Further, as the light source, any light source such as a known light source can be used.

The viewing side means the side where the observer of the displayed image is located when using the liquid crystal display device.

Normally, when the liquid crystal display is operated to change from a black display state (a state where black is displayed on the entire screen) to a white display state (a state where white is displayed on the entire screen) by gradually increasing the brightness, the display screen The brightness of will also gradually increase. For example, when an operation is performed to display an 8-bit gray scale (a black display state is 0, a white display state is 255, and an intermediate gradation is represented by a value of 0 to 255) on the display screen of the liquid crystal display device, the scale is As 0 is increased from 0 to 255, the brightness of the display screen also increases. However, depending on the viewing direction, when the operation of gradually increasing the brightness is performed, the brightness of the display screen may decrease in contrast. In this way, the operation of increasing or decreasing the brightness displayed on the display device and the actual increase or decrease of the brightness of the display screen do not coincide with each other, which is called “gradation inversion”. The gradation inversion may be observed at a certain azimuth angle when the display screen of the liquid crystal display device is viewed from an oblique direction. In the TN mode liquid crystal display device of the present invention, the angle formed by the azimuth angle at which the gradation is inverted when the display screen is viewed obliquely and the longitudinal direction of the hole-containing portion is 90 ° + θ1 (θ1 is 3 ° or more and 45 ° or less). ), It is possible to reduce such gradation inversion and widen the viewing angle.
The azimuth angle for gradation inversion is not limited to one direction, but may be two directions or an angle range having a certain degree of spread. In that case, the direction in which the viewing angle is most desired to be widened can be determined, and the longitudinal direction of the hole-containing portion can be set in the direction perpendicular to the direction.
In the TN mode liquid crystal display device of the present invention, as the polarizing plate of the present invention, the angle formed by the absorption axis of the polarizer and the longitudinal direction of the hole-containing portion is 45 ° + θ1 (θ1 is 3 ° or more and 45 ° or less). Some can be preferably used. Normal TN-mode liquid crystal display device (having a rectangular display screen, the display screen is upright in a substantially vertical direction, and is used in a state in which the long side direction of the rectangle is a horizontal direction and the short side direction is a substantially vertical direction. In many cases, gradation inversion is often observed when observed from the lower side. In a normal TN-mode liquid crystal display device, the polarizer often forms an angle of 45 ° between its absorption axis and the horizontal direction of the display screen. Therefore, when the polarizing plate of the present invention has an angle between the absorption axis of the polarizer and the longitudinal direction of the hole-containing portion of 45 ° + θ1 (θ1 is 3 ° or more and 45 ° or less), The angle formed by the absorption axis and the horizontal direction of the display screen is 45 °, and the angle formed by the longitudinal direction of the hole-containing portion and the horizontal direction of the display screen is inclined by θ1 (3 ° or more and 45 ° or less) from the parallel direction easily. Therefore, the viewing angle of the TN mode liquid crystal display device can be easily expanded.

[9.2. VA mode liquid crystal display device]
The viewing angle widening film of the present invention or the polarizing plate of the present invention is also preferably used in a VA mode liquid crystal display device.

The VA mode liquid crystal display device of the present invention is provided with the polarizing plate of the present invention and the VA mode liquid crystal cell in this order from the viewing side, and the polarizing plate has a viewing angle expansion film side as the viewing side. Will be arranged.

VA mode liquid crystal display devices usually include a polarizing plate and a light source on the side opposite to the viewing side of the VA mode liquid crystal cell. As the polarizing plate arranged on the side opposite to the viewing side, the polarizing plate of the present invention may be used, or a polarizing plate other than the polarizing plate of the present invention such as a known polarizing plate may be used. Further, as the light source, any light source such as a known light source can be used.

In the VA mode liquid crystal display device of the present invention, in the polarizing plate of the present invention, the angle formed by the longitudinal direction of the hole-containing portion and the direction parallel to the absorption axis of the polarizer is 3 ° or more and 45 ° or less. Those having an angle between the longitudinal direction of the hole-containing portion and the direction perpendicular to the absorption axis of the polarizer of 3 ° or more and 45 ° or less can be preferably used. In the case of disposing such a polarizing plate in an ordinary liquid crystal display device, the relationship between the longitudinal direction of the hole-containing portion and the long side direction of the display screen is arranged at an angle of 3 ° or more and 45 ° or less from the parallel or 3 from the vertical. It is preferable that the arrangement is such that the angle is not less than 45 ° and not more than 45 °. The longitudinal direction of the hole-containing portion may be 3 ° or more and 45 ° or less from the direction perpendicular to the azimuth angle direction required to widen the viewing angle. For example, in a display device having a rectangular display screen, when it is required to increase the viewing angle in the long side direction, the longitudinal direction of the hole containing portion is 3 ° with respect to the direction parallel to the short side direction. It is preferable that the arrangement is inclined at 45 ° or less. The longitudinal direction of the hole-containing portion may be an arrangement inclined by 3 ° or more and 45 ° or less from a direction parallel to the absorption axis of the polarizer or an arrangement inclined by 3 ° or more and 45 ° or less from a vertical direction. With such an arrangement, the viewing angle of the VA mode liquid crystal display device can be expanded.

[9.3. IPS-mode liquid crystal display device]
The viewing angle widening film of the present invention or the polarizing plate of the present invention is also preferably used in an IPS mode liquid crystal display device.

The IPS mode liquid crystal display device of the present invention is provided with the polarizing plate of the present invention and the IPS mode liquid crystal cell in this order from the viewing side, and the polarizing plate has the viewing side on the viewing side and the viewing side. Will be arranged.

An IPS-mode liquid crystal display device usually includes a polarizing plate and a light source on the side opposite to the viewing side of the IPS-mode liquid crystal cell. As the polarizing plate arranged on the side opposite to the viewing side, the polarizing plate of the present invention may be used, or a polarizing plate other than the polarizing plate of the present invention such as a known polarizing plate may be used. Further, as the light source, any light source such as a known light source can be used.

In the IPS mode liquid crystal display device of the present invention, in the polarizing plate of the present invention, the angle formed by the longitudinal direction of the hole-containing portion and the direction parallel to the absorption axis of the polarizer is 3 ° or more and 45 ° or less. It is preferable to use one having an angle between the longitudinal direction of the hole-containing portion and the direction perpendicular to the absorption axis of the polarizer of 3 ° or more and 45 ° or less. In the case of disposing such a polarizing plate in an ordinary liquid crystal display device, the relationship between the longitudinal direction of the hole-containing portion and the long side direction of the display screen is arranged at an angle of 3 ° or more and 45 ° or less from the parallel or 3 from the vertical. It is preferable that the arrangement is such that the angle is not less than 45 ° and not more than 45 °. The longitudinal direction of the hole-containing portion may be 3 ° or more and 45 ° or less from the direction perpendicular to the azimuth angle direction required to widen the viewing angle. For example, in a display device having a rectangular display screen, when it is required to increase the viewing angle in the long side direction, the longitudinal direction of the hole containing portion is 3 ° with respect to the direction parallel to the short side direction. It is preferable that the arrangement is inclined at 45 ° or less. The longitudinal direction of the hole-containing portion may be an arrangement inclined by 3 ° or more and 45 ° or less from a direction parallel to the absorption axis of the polarizer or an arrangement inclined by 3 ° or more and 45 ° or less from a vertical direction. With such an arrangement, the viewing angle of the IPS mode liquid crystal display device can be expanded.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples, and may be implemented by being arbitrarily modified within the scope of the claims and equivalents thereof.

In the following description, "%" and "parts" representing amounts are based on weight unless otherwise specified. The following operations were performed in a normal temperature and normal pressure atmosphere unless otherwise specified.

〔Evaluation methods〕
(Contrast ratio and Δγ)
The contrast ratio and Δγ of the liquid crystal display devices of Examples and Comparative Examples were measured.
A spectroradiometer (manufactured by Topcon, product name “SR-LEDW”) was used for the measurement. The contrast ratio was measured from the front direction of the display device (polar angle 0 °). At the time of measurement, the illuminance of light applied to the display surface of the device was 0 lux. The luminance in the white display state and the luminance in the black display state were measured, and the ratio of (luminance in white display state) / (luminance in black display state) was determined as a contrast ratio. A high contrast ratio indicates that the contrast ratio is good.

In addition, the color of each gradation from 0 (black) to 255 (white) on the 256 gradation gray scale was displayed, and the luminance was observed from the front direction and the direction of the polar angle of 75 °. The azimuth in the direction of the polar angle of 75 ° was the in-plane direction of the display device, which was perpendicular to the longitudinal direction of the hole-containing portion. In the example, the in-plane direction of the display device was perpendicular to the longitudinal direction of the hole-containing portion, and in the comparative example, the in-plane direction of the display device corresponding to each example. In the observation in each direction, the normalized brightness was calculated with the brightness at the gray scale 0 being 0% and the brightness at the gray scale 255 being 100%, and the relationship between the gray scale and the standardized brightness was obtained. The absolute value of the difference between the normalized luminance in the front direction and the normalized luminance in the polar angle 75 ° direction is calculated for each grayscale gradation, and the maximum value of these values is obtained as Δγ (%). It was A low Δγ indicates that the viewing angle characteristics are good.

(Evaluation of glare)
With respect to the liquid crystal display devices of Examples and Comparative Examples, when white display was performed, it was visually observed whether or not color separation occurred, and evaluated according to the following evaluation criteria.
A: No glare (color separation) B: Glitter (color separation) was slightly observed, but it was not enough to affect the image quality.
C: Glistening (color separation) was remarkable.

(Observation in the longitudinal direction of the hole containing part)
The hole-containing portions formed in the viewing angle widening films manufactured in Examples and Comparative Examples were observed using a digital microscope (manufactured by Keyence Corporation). The "longitudinal direction of the hole-containing portion" is defined as the direction connecting the positions 20A1 and 20A2 whose length in the longitudinal direction from the center 20P is ± 0.4L, where L is the total length of the hole-containing portion in the longitudinal direction. . Of the observed hole-containing parts, the longitudinal direction of 80% or more of the hole-containing parts was defined as the "longitudinal direction of the hole-containing parts".

[Example 1]
(1-1. Preparation of material film)
As the first film (material film), a multi-layer film having a layer structure of two layers of two types of skin layer / core layer was produced. As the material for the skin layer, a resin film 1 (trade name: ZEONOR film, manufactured by Nippon Zeon Co., Ltd., glass transition temperature 126 ° C., thickness 48 μm) containing a norbornene-based polymer (described as “COP” in the table) is used. I was there. As materials for the core layer, norbornene-based polymer 1 (trade name: Zeonex T62R, manufactured by Zeon Corporation) and hydrogenated C9-based petroleum resin 1 (trade name: Alcon P140, manufactured by Arakawa Chemical Industry Co., Ltd., number average) Molecular weight: 940, softening point: 140 ± 5 ° C.) was used.
The coating liquid 1 containing the material of the core layer (norbornene-based polymer 1 and hydrogenated C9-based petroleum resin 1) was applied to one surface of the resin film 1 using a die coater. Coating solution 1 was prepared by stirring 12 parts of norbornene-based polymer 1 and 3 parts of hydrogenated C9-based petroleum resin 1 together with 85 parts of cyclohexane for 24 hours. The coating amount of the coating liquid 1 was adjusted so that the thickness of the core layer after drying was 6 μm.
The resin film 1 coated with the coating liquid 1 was dried in an oven at 85 ° C. for 5 minutes to obtain a material film. The resulting material film had a width of 300 mm, a skin layer thickness of 48 μm, and a core layer thickness of 6 μm. The glass transition temperature of the resin forming the core layer was 148 ° C. The proportion of hydrogenated C9 petroleum resin 1 (hydrocarbon compound) in the resin constituting the core layer was 20%.

(1-2. Viewing angle expansion film)
A viewing angle widening film was manufactured using the apparatus schematically shown in FIGS. 4 and 5. In the apparatus, a blade made of SUS (blade tip R = 0.2 mm) was used as the blade 30.
The first film 10 obtained in (1-1) is arranged so that the surface on the core layer side is in contact with the blade 30, and the first film 10 is pressed against the blade 30 to adjust the tension of the first film 10. Craze processing was carried out at 500 N / m in the direction of arrow A11 at a speed of 50 mm / min to obtain a first film 11 including a hole-containing portion.
At the time of craze processing, the direction of the edge 30E of the blade 30 was the width direction (TD direction) of the first film. The angle θx formed by the center line 30C of the blade 30 observed from the extension direction of the edge 30E and the downstream surface of the first film 10 was set to 20 °.
The craze-processed film (first film 11 including a hole-containing portion) was stretched at a temperature of 130 ° C. in a direction of 5 ° with respect to its width direction (short side direction: XX line direction shown in FIG. 6) ( A viewing angle widening film 1 was obtained by continuously obliquely stretching in the direction of the angle θA shown in the drawing. In this viewing angle widening film, the longitudinal direction of the hole-containing portion was inclined by 5 ° with respect to the short side direction of the film.

The hole-containing part of the obtained viewing angle widening film appeared on the core layer side. The hole-containing portion is a substantially linear craze, the longitudinal directions of the hole-containing portion are substantially parallel to each other, and are inclined 5 ° with respect to the TD direction (short side direction) of the viewing angle widening film. It was The spacing P between the pore-containing portions was a random spacing of 26 μm or less. The average value of the width of each hole-containing portion was 6.2 μm, and the average value of the depth (hole height) of the hole-containing portion was 5 μm. These values were obtained by selecting three arbitrary points on the craze film and observing a 25 μm square area with a scanning electron microscope.

(1-3. Manufacturing of liquid crystal display device)
The viewing angle widening film obtained in (1-2) was attached to the polarizing plate on the viewing side surface of a linearly polarized light VA mode liquid crystal display device (BenQ, 27 inches, model GW2760HS). When laminating, the angle formed by the direction perpendicular to the absorption axis of the polarizer in the viewing side polarizing plate and the longitudinal direction of the hole-containing portion of the viewing angle widening film is θA (5 ° in Example 1), and The directions were adjusted so that the angle formed by the longitudinal direction of the hole-containing portion and the direction parallel to the short side direction of the rectangular display screen was θA (5 ° in Example 1). Further, the viewing angle widening film was attached such that the surface on the side where the hole-containing portion was formed was the viewing side. Thereby, the liquid crystal display device of the present invention was obtained.

(1-4. Evaluation)
With respect to the liquid crystal display device obtained in (1-3), the contrast ratio and Δγ were measured, and glare was visually evaluated, and the results are shown in Table 1.

[Examples 2 to 5, Comparative Examples 1 to 3]
A liquid crystal display device and its components were obtained and evaluated by the same operations as in Example 1 except for the following changes.
The stretching direction of the craze-processed film was set to be the stretching angle (θA) described in each table with respect to the width direction (short side direction: XX line direction shown in FIG. 6) of the film.

The hole-containing parts of the viewing angle widening films obtained in Examples 2 to 5 and Comparative Examples 2 to 3 were developed in the core layer. The hole containing portion is a substantially linear craze, the longitudinal direction of the hole containing portion is substantially parallel to each other, at an angle of θA with respect to the TD direction (short side direction) of the viewing angle widening film, It was inclined. The spacing P between the pore-containing portions was a random spacing of 26 μm or less. The average value of the width of each hole-containing portion was 6.2 μm, and the average value of the depth (hole height) of the hole-containing portion was 5 μm.

The hole-containing portion of the viewing angle widening film obtained in Comparative Example 1 appeared in the core layer. The hole-containing portion was a substantially linear craze, and the longitudinal directions of the hole-containing portion were substantially parallel to each other and parallel to the TD direction (short side direction) of the viewing angle widening film. The spacing P between the pore-containing portions was a random spacing of 26 μm or less. The average value of the width of each hole-containing portion was 6.2 μm, and the average value of the depth (hole height) of the hole-containing portion was 5 μm.

[Comparative Example 4]
A liquid crystal display device and its components were obtained and evaluated by the same operations as in Example 1 except for the following changes.
The stretching direction of the craze-processed film 11 was set to be parallel (θA = 0 °) to the width direction (short side direction: XX line direction shown in FIG. 6) of the film.
-The stretching temperature was 140 ° C.

The hole-containing portion of the viewing angle widening film obtained in Comparative Example 4 appeared in the core layer. The pore-containing portion was a substantially linear craze, and the longitudinal directions of the pore-containing portion were substantially parallel to each other and substantially parallel to the TD direction of the film. The interval P between the hole-containing parts was a random interval of 26 μm or less, and the average depth (height) of the hole-containing parts was 5 μm. Since the craze was filled during the stretching, the average width of the hole-containing portion was 0.01 μm.

As is clear from the results shown in Tables 1 to 3, the contrast ratios in Examples in which the longitudinal direction of the hole-containing portion is 3 ° or more and 45 ° or less with respect to the TD direction (short side direction) of the viewing angle widening film. Was 2100 or more, Δγ was 22 or less, and the evaluation of glare was A or B. That is, in the example using the viewing angle widening film of the present invention, a liquid crystal display device was obtained which was compatible with a high contrast ratio and a wide viewing angle and was able to eliminate the moire interference phenomenon.

1 ... Viewing angle widening film 10 ... First film (material film)
11 ... 1st film containing a hole containing part 20 ... Hole containing part 21 ... Craze (hole containing part)
211 ... Fibril 212 ... Hole 100 ... Craze processing device 30 ... Blade

Claims

A viewing angle expansion film for expanding the viewing angle,
The viewing angle widening film comprises a plurality of hole-containing portions on at least one surface, and is rectangular,
The hole-containing portion contains holes,
The longitudinal direction of the hole-containing portion is 3 ° or more and 45 ° or less with respect to the short side direction of the viewing angle widening film, or 3 ° or more and 45 ° or less with respect to the long side direction of the viewing angle widening film. A viewing angle expansion film.
The longitudinal direction of the hole-containing portion is 5 ° or more and 15 ° or less with respect to the short side direction of the viewing angle widening film, or 5 ° or more and 15 ° or less with respect to the long side direction of the viewing angle widening film. The viewing angle widening film according to claim 1.
With two or more resin layers,
The viewing angle widening film according to claim 1, wherein at least one of the resin layers is a layer including the hole-containing portion.
The viewing angle widening film according to any one of claims 1 to 3, wherein the viewing angle widening film is a polarizing plate protective film.
The viewing angle widening film according to any one of claims 1 to 4, wherein the hole-containing portion is made of craze.
A polarizing plate comprising the viewing angle widening film according to any one of claims 1 to 5 and a polarizer.
An angle formed by the longitudinal direction of the hole-containing portion and a direction parallel to the absorption axis of the polarizer is 3 ° or more and 45 ° or less, or a direction perpendicular to the longitudinal direction of the hole-containing portion and the absorption axis of the polarizer. The polarizing plate according to claim 6, wherein the angle formed by and is 3 ° or more and 45 ° or less.
The angle formed by the absorption axis of the polarizer and the longitudinal direction of the hole-containing portion is 45 ° + θ1,
The polarizing plate according to claim 6, wherein the θ1 is 3 ° or more and 45 ° or less.
A TN-mode liquid crystal display device comprising the polarizing plate according to claim 6 or 8 and a TN-mode liquid crystal cell in this order from the viewing side,
The polarizing plate is arranged such that the surface on the viewing angle widening film side is the viewing side,
The angle formed by the azimuth angle that causes gradation inversion when the display screen is viewed from an oblique direction and the longitudinal direction of the hole-containing portion is 90 ° + θ1.
A TN-mode liquid crystal display device in which θ1 is 3 ° or more and 45 ° or less.
A VA mode liquid crystal display device comprising the polarizing plate according to claim 6 or 7 and a VA mode liquid crystal cell in this order from the viewing side,
The polarizing plate is arranged such that the surface on the viewing angle widening film side is the viewing side,
A VA mode liquid crystal display device, wherein an angle formed by a longitudinal direction of the hole-containing portion and a direction perpendicular to an absorption axis of the polarizer is 3 ° or more and 45 ° or less.
An IPS mode liquid crystal display device comprising the polarizing plate according to claim 6 or 7 and an IPS mode liquid crystal cell in this order from the viewing side,
The polarizing plate is arranged such that the surface on the viewing angle widening film side is the viewing side,
An IPS-mode liquid crystal display device, wherein an angle formed by a longitudinal direction of the hole-containing portion and a direction perpendicular to an absorption axis of the polarizer is 3 ° or more and 45 ° or less.
A method of manufacturing a viewing angle widening film according to any one of claims 1 to 5,
Step 1 of forming the hole-containing portion on at least one surface of the first film,
A method for producing a viewing angle widening film, which comprises a step 2 of stretching the first film subjected to the step 1 to expand the hole diameter of the hole containing portion.
The method for manufacturing a viewing angle widening film according to claim 12, wherein in the step 2, the first film is obliquely stretched.
The first film comprises one or more resin layers,
In the step 1, the hole-containing portion is formed in one or more layers of the resin layer,
The viewing angle according to claim 12 or 13, wherein in the step 2, the first film is stretched at a temperature lower than a glass transition temperature of a resin forming a resin layer in which the hole-containing portion is formed. Enlarged film manufacturing method.