TW201832916A - Viewing angle expansion film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

Provided is a viewing angle expansion film for expanding the viewing angle, wherein the viewing angle expansion film is equipped with one or more resin layers among which one or more of the layers is a hole-containing layer equipped with multiple hole-containing sections which are substantially parallel to each other. The hole-containing sections contain holes, and the refractive index of the hole-containing layer is 1.53 or less. Also provided are a polarizing plate and a liquid crystal display device having this viewing angle expansion film.

Description

Viewing angle magnifying film, polarizing plate and liquid crystal display device

The present invention relates to a viewing angle magnifying film, a polarizing plate, and a liquid crystal display device.

Twisted Nematic (TN) mode and Vertical Alignment (VA) mode liquid crystal display devices have established technology and can be supplied at a lower price. On the other hand, the display surface is often viewed from an oblique direction. The display quality is poor or the available viewing angle is narrow. Specifically, the relationship between the brightness of the image displayed on the screen and the brightness measured by observing the image is quite different when viewed from the front and when viewed from an oblique direction, making it difficult to view the liquid crystal display device. Therefore, in the past, TN mode liquid crystal display devices were mainly used in small and medium-sized televisions, personal computers, and other display devices viewed from a predetermined angle. However, in recent years, devices such as tablet-type terminal devices that require viewing under a wide viewing angle have also tried means to enlarge the viewing angle, and at the same time tried to use these modes of liquid crystal display.

As an example of a means for enlarging the viewing angle, a retardation layer having a specific phase difference to compensate the viewing angle is known. In addition, various proposals have been made for a method of manufacturing such a retardation layer (for example, Patent Document 1: Japanese Patent Publication No. 2013-151162 (corresponding to another application: US Patent Application Publication No. 2002/180107) and patent Document 2: International Patent Publication No. 2009/084661 (corresponding to another application: US Patent Application Publication No. 2011/039084).

However, there is a demand for a display device capable of achieving good display in a wider range of viewing angles. Specifically, the required display device, while maintaining the contrast of the liquid crystal display device at a high level, is also concerned with its tone brightness characteristics (the relationship between the brightness of the image displayed on the screen and the brightness measured by observing this image), The tone luminance characteristics viewed from the oblique direction are close to the tone luminance characteristics viewed from the front.

Therefore, an object of the present invention is to provide a viewing angle magnifying film, a polarizing plate, and a liquid crystal display device capable of achieving high contrast and a wide range of viewing angles.

As a result of research conducted by the present inventors in order to solve the aforementioned problems, they have found that this can be solved by applying a thin film including a layer material having a specific refractive index and having a specific structure in the layer as a viewing angle magnifying film to a display device. The subject has further completed the present invention.

That is, the present invention is as follows.

[1] A viewing angle magnifying film, which is a viewing angle magnifying film for magnifying a viewing angle, wherein the viewing angle magnifying film includes one or more resin layers; one or more of the resin layers are pore-containing layers; and the pore-containing layers are provided with each other The plurality of pore-containing portions that are approximately parallel; the pore-containing portion includes pores; and the pore-containing layer has a refractive index of 1.53 or less.

[2] The viewing angle magnifying film according to [1], wherein the resin constituting the pore-containing layer is an amorphous resin.

[3] The viewing angle magnifying film according to [1] or [2], comprising the resin layer of two or more layers.

[4] The viewing angle magnifying film according to any one of [1] to [3], wherein an interval between the adjacent hole-containing portions is a random interval of 50 μm or less.

[5] The viewing angle magnifying film according to any one of [1] to [4], which contains an ultraviolet absorber.

[6] The viewing angle magnifying film according to any one of [1] to [5], wherein the viewing angle magnifying film is a polarizing plate protective film.

[7] The viewing angle magnifying film according to any one of [1] to [6], wherein the hole-containing portion includes a crack.

[8] A polarizing plate including a viewing angle magnifying film and a polarizer as described in any one of [1] to [7].

[9] The polarizing plate according to [8], wherein a longitudinal direction of the hole-containing portion is parallel to or perpendicular to an absorption axis of the polarizer.

[10] The polarizing plate according to [8], wherein an included angle between the absorption axis of the polarizer and the longitudinal direction of the hole-containing portion is 45 °.

[11] A TN mode liquid crystal display device sequentially provided with the polarizing plate as described in [8] or [9] and a TN mode liquid crystal cell from the viewing side, wherein the polarizing plate is disposed on the viewing angle magnifying film side. The surface is the viewing side; when the display screen is viewed from an oblique direction, the included angle of the inversion of the tone is perpendicular to the longitudinal direction of the aforementioned hole-containing portion.

[12] A VA mode liquid crystal display device sequentially provided with the polarizing plate as described in [8] or [9] and a VA mode liquid crystal cell from the viewing side, wherein the polarizing plate is arranged on the viewing angle magnifying film side. The face is the viewing side.

According to the present invention, a viewing angle magnifying film, a polarizing plate, and a liquid crystal display device capable of achieving high contrast and a wide range of viewing angles are provided.

In the following, the embodiments and examples of the present invention will be disclosed for detailed description. However, the present invention is not limited to the implementation modes and exemplified examples disclosed below, and can be implemented with arbitrary changes without departing from the scope of the patent application of the present invention and its equivalent range.

In the following description, the "polarizing plate" includes not only a rigid component but also a component having flexibility such as a resin film.

In the following description, the direction of the constituent elements is the so-called "45 °", "parallel", "vertical" or "orthogonal". Unless otherwise noted, it can also include within the scope that does not impair the effect of the present invention. For example, the error is usually within a range of ± 5 °, preferably ± 2 °, and preferably within ± 1 °.

Moreover, in the following description, the MD direction (machine direction) is the direction of travel of the film in the manufacturing line; the TD direction (traverse direction) is a direction parallel to the film surface and a direction perpendicular to the MD direction. In addition, in order to act cheaply, the longitudinal direction of the 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, a "long-length" film is referred to as a film having a length of 5 times or more with respect to the width, and preferably a length of 10 times or more, and is specifically referred to as having a rolled product. Film in roll form to a degree of storage or transport. The upper limit of the length of the elongated film is not particularly limited, and may be, for example, 100,000 times or less the width.

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

[1. Overview of viewing angle magnifying film]

The viewing angle magnifying film of the present invention is a film for magnifying the viewing angle of a liquid crystal display device.

The viewing angle magnifying film includes one or more resin layers. One or more of the resin layers are pore-containing layers.

[2. Materials with pore layer]

The pore-containing material is obtained as a resin containing various polymers. Examples of the polymer include polystyrene, polypropylene, polyethylene, polyester, polyamide, polyvinylidene fluoride, and an alicyclic structure-containing polymer. However, from the viewpoint of easily forming a pore-containing portion, In other words, polystyrene, polypropylene, and alicyclic structure-containing polymers are preferred.

Polystyrene is a polymer containing a repeating unit derived from a styrene-based monomer (hereinafter, appropriately referred to as a "styrene-based monomer unit"). The styrene-based monosystem means styrene and a styrene derivative. Examples of styrene derivatives include α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminestyrene, p-carboxystyrene, and p-phenylstyrene. The styrenic monomers may be used singly or in combination of two or more kinds in any ratio. Therefore, the styrenic polymer may contain one kind of styrenic monomer unit alone, or may contain two or more kinds of styrenic monomer unit in any ratio.

The polystyrene may be a homopolymer or a copolymer containing only a styrene-based monomer, or may be a copolymer of a styrene-based monomer and another monomer. Examples of monomers copolymerized with styrene-based monomers include ethylene, propylene, butadiene, isoprene, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, and N-phenylcis Butylenediimine, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, maleic anhydride, acrylic acid, methacrylic acid, and vinyl acetate. These monomers may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

Polypropylene may be a homopolymer of propylene or a copolymer with a monomer other than propylene. When polypropylene is a copolymer, polypropylene may be a random polymer, a block copolymer, or a graft polymer. However, when polypropylene is a copolymer, it is preferable that the content of the repeating unit derived from propylene contained in polypropylene is high. Specifically, it is preferably 80% by weight or more, and 85% by weight or more. good.

Examples of the alicyclic structure-containing polymer include (1) a norbornene-based polymer, (2) a monocyclic cyclic olefin-based polymer, (3) a cyclic conjugated diene-based polymer, (4) Vinyl alicyclic hydrocarbon polymers, and hydrides such as (1) to (4). Among these, from the viewpoints of heat resistance and mechanical strength, a norbornene-based polymer and a hydride thereof are preferred.

Examples of the olefin-reducing polymer include a ring-opening polymer of a olefin-reducing monomer, a ring-opening copolymer formed by the olefin-reducing monomer and another monomer capable of ring-opening copolymerization, and hydrides thereof; Addition polymers of olefin monomers, addition copolymers of olefinic monomers and other monomers capable of copolymerization, etc. Among them, from the viewpoint of transparency, a hydride of a ring-opening polymer of a norylene monomer or a hydride of a ring-opening copolymer formed of a norylene monomer and another monomer capable of ring-opening copolymerization is preferable. .

[2.1. Hydrogenated block copolymer [G]]

Examples of the alicyclic structure-containing polymer include a hydrogenated block copolymer [G] including two or more polymer blocks [D] and one or more polymer blocks [E]; the aforementioned polymer The block [D] has a cyclic hydrocarbon group-containing compound hydride unit [I], and the aforementioned polymer block [E] has a chain hydrocarbon compound hydride unit [II] or a combination of a unit [I] and a unit [II].

[2.1.1. Cycloalkyl-containing compound hydride unit [I]]

The cyclic hydrocarbon group-containing compound hydride unit [I] is a structural unit having the following structure: a structure obtained by polymerizing a cyclic hydrocarbon group-containing compound, and further hydrogenating its unsaturated bond if the unit obtained by the polymerization has an unsaturated bond. However, as long as the cyclic hydrocarbon compound-containing hydride unit [I] has the structure, it may include a unit obtained by an arbitrary production method.

The cyclic hydrocarbon 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 an unsaturated bond thereof". However, as long as the aromatic vinyl compound hydride unit [I] has this structure, it may include a unit obtained by an arbitrary production method.

Similarly, in this case, a structural unit having "a structure obtained by polymerizing styrene and hydrogenating an unsaturated bond thereof" may be referred to as a styrene hydride unit. The styrene hydride unit may include a unit obtained by an arbitrary production method as long as it has this structure.

Examples of the aromatic vinyl compound hydride unit [I] include a structural unit represented by the following structural formula (1).

[Chemized 1] (1)

In the structural formula (1), R ^C represents an alicyclic hydrocarbon group. Examples of R ^C include cyclohexyls such as cyclohexyl, and decahydronaphthyls.

In the structural formula (1), R ¹ , R ^2, and R ³ each independently represent a hydrogen atom, a chain hydrocarbon group, a halogen atom, an alkoxy group, a hydroxyl group, an ester group, a cyano group, a fluorenyl group, a fluorenimine group, and a silyl group. Or a chain hydrocarbon group substituted with a polar group (halogen atom, alkoxy group, hydroxyl group, ester group, cyano group, amidino group, amidino group, and 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 in terms of heat resistance, low birefringence, and mechanical strength. The chain hydrocarbon group is preferably a saturated hydrocarbon group, and more preferably an alkyl group.

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

［Chemical 2］ (1-1)

The exemplified cyclic hydrocarbon group-containing compound hydride unit [I] has stereoisomers, and any of the stereoisomers may be used. The cyclic hydrocarbon group-containing compound hydride unit [I] may be used singly or in combination of two or more kinds in any ratio.

[2.1.2. Chain compound hydride unit [II]]

The chain hydrocarbon compound hydride unit [II] is a structural unit having a structure in which a chain hydrocarbon compound is polymerized, and if the unit obtained by the polymerization has an unsaturated bond, its unsaturated bond is further hydrogenated. However, the chain hydrocarbon compound hydride unit [II] may include a unit obtained by an arbitrary production method as long as it has this structure.

The hydrocarbon compound hydride unit [II] is preferably a structural unit obtained by polymerization of a diene compound. More specifically, it is a structural unit (a structure obtained by polymerizing a diene compound and obtaining a structure obtained by further hydrogenating an unsaturated bond if the unit obtained by the polymerization has an unsaturated bond) (a diene compound hydride unit [ II]). However, as long as the diene compound hydride unit [II] has this structure, it may include a unit obtained by an arbitrary production method.

Similarly, in this case, a structural unit having "a structure obtained by polymerizing isoprene and hydrogenating its unsaturated bond" is sometimes referred to as an isoprene hydride unit. The isoprene hydride unit may include a unit obtained by an arbitrary production method as long as it has this structure.

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

［Chemical 3］ (2)

In the structural formula (2), R ⁴ to R ⁹ each independently represent a hydrogen atom, a chain hydrocarbon group, a halogen atom, an alkoxy group, a hydroxyl group, an ester group, a cyano group, a fluorenyl group, a fluorenimine group, a silicon group, or A hydrocarbon group substituted with a polar group (halogen atom, alkoxy group, hydroxyl group, ester group, cyano group, amido group, amidino group, 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 viewpoints of heat resistance, low birefringence, and mechanical strength. The chain hydrocarbon group is preferably a saturated hydrocarbon group, and more preferably an alkyl group.

［Chemical 4］ (3)

In the structural formula (3), R ¹⁰ to R ¹⁵ each independently represent a hydrogen atom, a chain hydrocarbon group, a halogen atom, an alkoxy group, a hydroxyl group, an ester group, a cyano group, a fluorenylamino group, a fluorenimine group, a silicon group, or A hydrocarbon group substituted with a polar group (halogen atom, alkoxy group, hydroxyl group, ester group, cyano group, amido group, amidino group, 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 viewpoints of heat resistance, low birefringence, and mechanical strength. The chain hydrocarbon group is preferably a saturated hydrocarbon group, and more preferably an alkyl group.

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

［Chemical 5］ (2-1) (2-2) (2-3)

The exemplified chain hydride unit [II] has stereoisomers, and any of the stereoisomers may be used. The hydrocarbon compound hydride unit [II] may be used singly or in combination of two or more kinds in any ratio.

[2.1.3. Details of hydrogenated block copolymer [G]]

The hydrogenated block copolymer [G] preferably has a triblock molecular structure, which has 1 block [E] per molecule and 2 blocks [D] per molecule, The two blocks [D] are connected to both ends of the block [E]. That is, the hydrogenated block copolymer [G] is preferably a triblock copolymer including: one block [E] per molecule; one block [D1] per molecule ], Which is connected to one end of the block [E] and has a cyclic hydrocarbon compound-containing hydride unit [I]; and has 1 block [D2] per molecule, which is connected to the other end of the block [E] , And has a cyclic hydrocarbon-containing compound hydride unit [I].

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

In addition, in the hydrogenated block copolymer [G] as the above-mentioned triblock copolymer, the weight of the block [D1] and the block [D2] is considered from the viewpoint of easily obtaining a pore-containing layer having good characteristics. It is better that the ratio D1 / D2 falls within a specific range. Specifically, the weight ratio D1 / D2 is preferably 1 or more, more preferably 3 or more, more preferably 5 or more, and more preferably 15 or less, more preferably 14 or less, and even more 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; and preferably 85,000 or less, more preferably 80,000 or less, and 75,000 or less Especially good. By setting the weight average molecular weight Mw within the aforementioned range, a pore-containing layer having better characteristics can be easily obtained.

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, particularly preferably 1.5 or less, and more than 1.0 Better. When the weight average molecular weight Mw is within the aforementioned range, the viscosity of the polymer can be reduced and the moldability can be improved.

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

The block [D1] and the block [D2] are preferably each independently composed only of the cyclic hydrocarbon group-containing compound hydride unit [I], but may include any unit other than the cyclic hydrocarbon group-containing compound hydride unit [I]. As an example of an arbitrary structural unit, the structural unit based on a vinyl compound other than a cyclic hydrocarbon group-containing compound hydride unit [I] is mentioned. The content rate of the arbitrary 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] is preferably made only from the alkane compound hydride unit [II], or is preferably made only from the cyclic hydrocarbon compound-containing hydride unit [I] and the alkane compound hydride unit [II], but Any unit other than units [I] and [II] must be included. Examples of arbitrary structural units include structural units based on vinyl compounds other than the units [I] and [II]. The content of the arbitrary 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] includes a cyclic hydrocarbon compound-containing hydride unit [I] and a chain hydrocarbon compound hydride unit [II], the weight ratio of the units [I] and [II] in the block [E] [I] / [II], preferably 0.1 or more, more preferably 0.2 or more, more preferably 0.3 or more, and more preferably 1.5 or less, more preferably 1.4 or less, and even more preferably 1.3 or less.

In addition, in the molecule of the hydrogenated block copolymer [G], the weight ratio [I] / [II] of the units [I] and [II] is preferably 70/30 or more, and more preferably 72/28 or more. 74/26 or higher is particularly preferred, 89/11 or lower is preferred, 85/15 or lower is preferred, and 83/17 or lower is particularly preferred. By setting the ratio of the units [I] and [II] within the aforementioned range, a pore-containing layer having better characteristics can be easily obtained.

The production method of the hydrogenated block copolymer [G] is not particularly limited, and an arbitrary production method may be adopted. The hydrogenated block copolymer [G] can be produced, for example, by preparing monomers corresponding to the cyclic hydrocarbon compound-containing hydride unit [I] and the chain hydrocarbon compound hydride unit [II], polymerizing these, and then Polymer [F] obtained by hydrogenation. The specific manufacturing method can be implemented by appropriately combining, for example, the method described in International Patent Publication No. WO2016 / 152871 and other known methods. The hydrogenation rate in the hydrogenation reaction is usually 90% or more, preferably 95% or more, and more preferably 97% or more. By increasing the hydrogenation rate, the low birefringence and thermal stability of the hydrogenated block copolymer [G] can be improved. The hydrogenation rate can be measured by ¹ H-NMR.

[2.2. Characteristics of resin constituting pore-containing layer]

In the resin constituting the pore-containing layer, the weight-average molecular weight of the polymer is a polystyrene-equivalent or polyisoprene-equivalent weight-average molecular weight measured by gel chromatography, and is usually 5,000 or more, and preferably 10,000 or more It is preferably 15,000 or more, and usually 50,000 or less, 45,000 or less is preferable, and 40,000 or less is preferable.

The resin constituting the pore-containing layer may contain an optional component other than the polymer as required. Examples of the optional components include ultraviolet absorbers, antioxidants, heat stabilizers, light stabilizers, antistatic agents, dispersants, chlorine capture agents, flame retardants, crystallization nucleating agents, reinforcing agents, and anti-caking agents. , Anti-fogging agents, release agents, pigments, organic or inorganic fillers, neutralizers, lubricants, decomposers, metal deactivators, antifouling agents and antibacterial agents.

Examples of the ultraviolet absorber include oxybenzophenone-based compounds, benzotriazole-based compounds, salicylate-based compounds, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and acrylic Nitrile-based ultraviolet absorbers, triazine-based compounds, nickel-salt-based compounds, and inorganic powders. Preferred examples of the ultraviolet absorber include: 2,2'-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazole-2 -Yl) phenol), 2- (2'-hydroxy-3'-tertiary butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2,4-di-tertiary butyl- 6- (5-chlorobenzotriazol-2-yl) phenol, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrakis Hydroxybenzophenone. Particularly suitable examples include: 2,2'-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol).

When the resin constituting the pore-containing layer 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.

The resin constituting the pore-containing layer is preferably an amorphous resin. By using an amorphous resin, even if the resin used is not a resin with an extremely low refractive index, a good viewing angle magnification effect can be obtained.

The crystallinity of the resin can be determined using a differential scanning thermal analysis (DSC). Specifically, the resin used as a target for determining crystallinity can be analyzed using a differential scanning thermal analysis (DSC) in accordance with JIS K7121 at a temperature increase rate (temperature increase mode) of 10 ° C / minute. In this analysis, when there is an endothermic peak, it can be determined as a crystalline resin.

The resin constituting the pore-containing layer preferably has a tensile elongation below a specific value. Specifically, the resin of the measurement object is formed into a single 20 μm thin film, and then punched into a dumbbell-shaped test piece. The aforementioned test piece is measured at ISO527-3 (test speed: 50 mm / min). The measured tensile elongation is preferably below a specific value. The tensile elongation is preferably 6% or less, and more preferably 4% or less. The lower limit of the tensile elongation is not particularly limited, but is, for example, 0.3% or more. By using such a resin exhibiting low tensile elongation, formation of cracks as pore-containing portions can be easily performed.

[3. Characteristics of Porous Layer]

The pore-containing layer has a refractive index of 1.53 or less, and preferably 1.51 or less. By setting the refractive index of the pore-containing layer to be lower than the aforementioned specific value, the effect of magnifying the viewing angle caused by the pore-containing layer can be improved, and the effective effect of the present invention can be obtained. The lower limit of the refractive index is not particularly limited, but it is determined to be, for example, 1.48 or more.

The refractive index of the pore-containing layer referred to in this case refers to the refractive index of the material constituting the pore-containing layer that does not have a pore-containing portion. The measurement of the refractive index of the pore-containing layer in the viewing angle magnifying film can be performed by measuring the refractive index of the layer with an appropriate measuring device after the pores of the pore-containing layer have disappeared by, for example, heating and pressing. Specifically, at a proper temperature, the holes in the area where the viewing angle magnifying film is pressed to at least a part disappear and become transparent, and then the refractive index of the area is measured. The temperature suitable for pressurization is Tg or more or Tm or more of the resin constituting the pore-containing layer, and is determined to be (Tg + 10) ° C or less (Tm + 10) ° C or less of the resin. As the measuring device, a refractive index / film thickness measuring device such as a prism coupler may be used.

In the case where the hole-containing layer has optical anisotropy, its refractive index is (nx + ny) / 2.

The viewing angle magnifying film of the present invention may include only one layer containing a hole, or may include two or more layers. When the viewing angle enlarging film of the present invention has two or more pore-containing layers, the materials exemplified above may be used as materials constituting each resin layer.

The thickness of the pore-containing layer is preferably 4 μm or more, more preferably 8 μm or more, and more preferably 90 μm or less, and more preferably 60 μm or less. When the viewing angle magnifying film includes two or more pore-containing layers, the total thickness of the pore-containing layer is preferably within this range. By setting the thickness of the pore-containing layer within this range, the pore-containing layer having the effect of the present invention can be easily constructed.

[4. Resin layer other than pore-containing layer]

The viewing angle magnifying film of the present invention may include only a pore-containing layer as a resin layer, or may include any resin layer including a pore-containing layer and a non-pore-containing layer in combination. By combining the hole-containing layer and the other resin layers, a useful viewing angle magnifying film can be formed.

As an example of this arbitrary resin layer, a reinforcing layer having a higher strength than the pore-containing layer may be mentioned. Because the hole-containing layer contains holes, the strength becomes low. At this time, by providing the reinforcing layer, a viewing angle magnifying film having both optical performance and strength can be obtained.

As another example of the arbitrary resin layer, a protective layer provided on one or both of the front face and the back face of the hole-containing layer may be mentioned. Because the hole-containing layer contains holes, its surface has irregularities. At this time, by providing the aforementioned protective layer, a viewing angle magnifying film having both optical performance and surface smoothness can be obtained. The protective layer may also have a function as the above-mentioned reinforcing layer. For example, the viewing angle magnifying film of the present invention may be defined as a layered structure having two kinds of three layers of a surface layer / core layer / surface layer, a core layer may be defined as a porous layer, and a surface layer may be defined as having a reinforcement Layer and / or protective layer.

As another example of the arbitrary resin layer, an easy-to-bond layer for improving the bondability between the viewing angle magnifying film and other parts is mentioned.

In the case where the viewing angle magnifying film of the present invention has a resin layer other than the porous layer, the resin constituting this 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, those having the desired characteristics may be appropriately selected in the above-mentioned examples of the resin constituting the pore-containing layer.

The thickness of the viewing angle magnifying film is preferably 5 μm or more, more preferably 10 μm or more, and even 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 even more preferably 40 μm or less.

[5. With holes]

The pore-containing layer in the viewing angle magnifying film of the present invention is provided with a plurality of pore-containing portions which are approximately parallel to each other, and the pore-containing portions include holes.

FIG. 1 is a plan view schematically showing an example of a viewing angle magnifying film. In the example of FIG. 1, the elongated viewing angle magnifying film 1 is composed of only one hole-containing layer, and includes a plurality of linear hole-containing portions 20 parallel to each other. The hole-containing portion 20 is shown in FIG. 1 as a thin line, but the hole-containing portion 20 has a width and a depth area, and includes a plurality of holes (not shown in FIG. 1). In the example of FIG. 1, the longitudinal direction of the hole-containing portion 20 is a direction parallel to the TD direction of the viewing angle magnifying film 1.

Since the hole-containing portion contains holes, light incident on the hole-containing portion is scattered. In addition, since the pore-containing portion contains pores, the refractive index of the pore-containing portion exhibits a refractive index different from that of the portion where the pore-containing portion is not formed. As a result, the angle of the light scattering direction must be widened. Although it is not limited to a specific theory, it is considered that the magnification of the viewing angle is achieved because light is scattered to such a wide range.

The hole included in the hole-containing portion may or may not pass through in the thickness direction of the viewing angle magnifying film. In either case, the hole-containing portion has a structure having a depth in the thickness direction of the viewing angle magnifying film because the hole-containing portion contains a hole. Each hole-containing portion usually has a plurality of holes, but the structure of the hole-containing portion is not limited to this, and may be formed by a single crack-shaped hole. The depth of the hole-containing portion may be the entire thickness direction of the hole-containing layer, or may be only a part thereof.

The plurality of hole-containing portions are arranged approximately parallel to each other. The so-called pore-containing portions are "approximately parallel" to each other within the range in which the effects of the present invention can be obtained, and the angle formed by each other may be an angle exceeding 0 °. Specifically, the error may be within ± 40 ° and within ± 30 °. Since the hole-containing portions that are "almost parallel" to each other have such an angular relationship, in the hole-containing layer, a plurality of hole-containing portions may have intersections with each other.

Each hole-containing portion usually has a substantially straight shape. The shape of the so-called hole-containing portion is "slightly straight", and includes the case where there is a wrinkle within the range where the effect of the present invention can be obtained.

In addition, from the viewpoint of easily forming the hole-containing portion, the longitudinal direction of the hole-containing portion is preferably approximately parallel to the TD direction of the viewing angle magnifying film (approximately perpendicular to the MD direction). In this case, as shown in an example disclosed in FIG. 1, it is not necessary to form a linear shape from one end portion of the viewing angle magnifying film 1 to the other end portion opposite to the end portion.

The interval P between adjacent hole-containing portions may be fixed or random. For example, in the example disclosed in FIG. 1, the interval P between adjacent hole-containing portions 20 is not fixed and becomes a random interval. From the viewpoint that a high viewing angle magnification effect can be obtained, the interval between the hole-containing portions is preferably random.

The interval P between adjacent hole-containing portions is not particularly limited, but in terms of suppressing moiré wave-like interference and the like and obtaining a good display screen quality, a narrow interval is preferable. The interval P is specifically preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 5 μm or less. When the interval P is random, the maximum value of the interval P in the viewing angle magnifying film is preferably at most the upper limit. In addition, the lower limit of the interval P is not particularly limited, but is set to be 0.5 μm or more.

In a preferred aspect, a part or all of the plurality of hole-containing portions provided in the viewing angle magnifying film are formed by cracks. From the viewpoint of easily forming the pore-containing portion, the pore-containing portion is preferably formed by cracks.

A crack refers to a slightly linear crack formed in a film. A crack usually has a fibril formed between the cracks and a void formed as a hole therebetween. Fibril means a fiber obtained by fibrillation of molecules constituting a resin.

FIG. 2 is an enlarged schematic view showing an example of a crack structure. In FIG. 2, the crack 21 has a plurality of elongated fibrils 211 and a gap 212 existing therebetween. The fibrils 211 usually extend in a direction approximately orthogonal to the longitudinal direction of the crack containing the pores, and exist. By performing crack processing on the thin film, cracks having such a structure can be formed. The film is cracked to apply pressure to the film, thereby forming a crack in the film, and further fibrillating the molecules constituting the resin in the gap between the cracks, thereby forming a gap between the fibril and the fibril. Details of the crack processing will be described later.

The diameter of the fibril 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 gap in the crack is usually 5 nm to 45 nm, and preferably 10 nm to 30 nm. When a hole-containing portion is formed by a crack, the width of the crack is usually 20 nm to 800 nm, preferably 30 nm to 600 nm, and more preferably 40 nm to 300 nm. The crack 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. Here, the values of the fibril diameter, gap diameter, crack width, and crack height are average values. Specifically, any three places where cracks are found by scanning electron microscope observation are measured for fibril fibers and gaps. To find the size.

[6. Shape and physical properties of viewing angle magnifying film]

The viewing angle magnifying film of the present invention may be a long film or a single film. From the viewpoint of improving manufacturing efficiency, generally, a viewing angle-enlarging film is made into a long strip film. In addition, in the case of manufacturing a monolithic viewing angle magnifying film, it is necessary to produce a monolithic viewing angle magnifying film by cutting a long viewing angle magnifying film into a desired shape.

The viewing angle magnifying film of the present invention may be a film with small optical anisotropy and substantially optical isotropy, or a film with optical anisotropy. In the case where the viewing angle magnifying film is optically anisotropic, the anisotropy may be caused by a pore-containing layer, may be caused by a layer body other than the pore-containing layer, or may be caused by the foregoing two.

In the case where the viewing angle magnifying 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, and even 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 more 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 even more preferably 300 nm or less. The lower limit is not particularly limited, and is preferably 10 nm or more, more preferably 20 nm or more, and more preferably 30 nm or more.

The total light transmittance of the viewing angle magnifying film is preferably 70% or more, and more preferably 80% or more. The light transmittance was measured in accordance with JIS K0115 using a spectrophotometer (manufactured by JASCO Corporation, UV-Vis near-infrared spectrophotometer "V-570").

[7. Manufacturing method of viewing angle magnifying film]

The viewing angle magnifying film of the present invention can be produced by any method such as a conventional method. For example, after the thin film for providing the formation of the hole-containing portion is manufactured, the hole-containing portion is formed on one or more layers of the film, thereby manufacturing the viewing angle magnifying film of the present invention. In this case, the film provided for forming the hole-containing portion may be referred to as a "material film".

[7.1. Manufacture of material film]

The layer structure of the material film is not particularly limited, and it can be used as the layer structure of the layer structure suitable for the intended viewing angle magnifying film. For example, it can be set as a layer structure including "a layer to be a pore-containing layer" and "a layer to be a resin layer other than that". More specifically, a combination of "a layer body having a hole-containing layer by crack processing" and "a layer body having no cracks even by this crack processing" is combined to obtain a material film which is used to A viewing angle magnifying film including a hole-containing layer and a resin layer other than the hole-containing layer was obtained.

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

Conditions such as the temperature of the molten resin during the production of the material film may be appropriately changed depending on the type of the material film, and may be performed under conventional conditions.

When the material film includes two or more resin layers, examples of the method for producing the material film include a co-extrusion T-die method, a co-extrusion inflation method, a co-extrusion lamination method, a dry lamination, and a co-casting Method and coating molding method.

The material film may be an unstretched unstretched film or a stretched stretched film. In general, the stretch elongation of a stretched film is small, and cracks are more likely to be formed. Therefore, a stretched film formed of, for example, a certain material and an unstretched film formed of the same material are bonded together as a multilayer material film, and cracks can be found only in the stretched film by performing crack processing on this. The stretching method used to obtain the stretched film may be either uniaxial stretching or biaxial stretching, but biaxial stretching is preferred. Among them, a suitable implementation type is a biaxial extension with a high extension ratio in the TD direction of the material film.

Extension can be performed using conventional extension devices. Examples of the stretching device include a vertical uniaxial stretching machine, a tenter stretching machine, a bubble stretching machine, and a roll stretching machine.

The elongation temperature is preferably (Tg−30 ° C) or higher, more preferably (Tg−10 ° C) or higher, and more preferably (Tg + 60 ° C) or lower, and more preferably (Tg + 50 ° C) or lower. Herein, "Tg" means the glass transition temperature of the resin.

The stretching ratio is preferably 1.2 to 5 times, more preferably 1.5 to 4 times, and even more preferably 2 to 3 times. For example, in the case where the biaxial extension is extended in different directions, the total extension ratio represented by the product of the extension ratios in each extension direction preferably falls within the aforementioned range.

[7.2. Formation of pores]

After the material film is manufactured, a hole-containing portion is formed on the surface of the material film to obtain a viewing angle magnifying film.

As an example of a specific method of forming the hole-containing portion, crack processing may be mentioned. By performing the crack processing, it is possible to efficiently produce a viewing angle magnifying film in which a hole-containing portion is cracked.

The crack processing can be performed by any method such as a conventional method. Examples of crack processing include Japanese Patent Publication No. H6-82607, Japanese Patent Publication No. H7-146403, Japanese Patent Publication No. H9-166702, Japanese Patent Publication No. H9-281306, and WO2007. / 046467, Japanese Patent Publication No. 2006-313262, Japanese Patent Publication No. 2009-298100, and Japanese Patent Publication No. 2012-167159.

A specific example of the crack processing will be described with reference to FIGS. 3 and 4. FIG. 3 is a perspective view schematically showing an example of a crack processing device, and FIG. 4 is a side view showing the vicinity of the blade of FIG. 3 in an enlarged manner. Figure 4 shows the device viewed from the TD direction.

In the example of FIG. 3, the crack processing apparatus 100 includes a lead-out roller 41, conveyance rollers 42 and 43, and a blade 30. The blade 30 includes a cutting edge 30E extending in a direction parallel to the TD direction.

In the operation of the crack processing apparatus 100, the material film 10 conveyed in the direction of the arrow A11 from the lead-out roller 41 is supported by the conveying rollers 42 and 43 while being pressed against the blade edge 30E of the blade 30. transport. As a result, pressure can be applied to the material film 10. As a result, the surface of the material film 10 is deformed due to pressure, and the hole-containing portion 20 extending in a direction approximately parallel to the TD direction can be formed, and the viewing angle magnifying film 1 can be manufactured.

In crack processing, the angle at which the blade 30 contacts the material film 10 must be appropriately adjusted to an angle at which a desired crack can be formed. In the examples of FIGS. 3 and 4, this angle is expressed as an angle θ between the center line 30C of the blade 30 and the downstream side surface of the material film 10 when viewed from the extension direction of the cutting edge 30E. The angle θ is preferably 10 ° to 60 °, more preferably 15 ° to 50 °, and even more preferably 20 ° to 40 °.

The tension of the material film when the blade is abutted against the material film can be appropriately adjusted to a value that can form an expected crack. The tension is preferably 100 N / m to 1000 N / m, and more preferably 300 N / m to 800 N / m.

When the material film is stretched, the crack processing may be performed before the material film is stretched, or may be performed simultaneously with the stretch processing.

When a material film having two or more resin layers is used as the material film and cracking is performed on the material film, cracks may occur in two or more resin layers, and cracks may occur in only a part of the resin layers. In addition, in a case where cracks occur only in a part of the resin layer, a crack may occur in the outermost layer, and a crack may occur in the inner layer. For example, in the case of crack processing of a thin film of a material "made of a core layer of a brittle material with a small tensile elongation and a surface layer of a softer material on the front and back", cracks can be generated only in the core layer. Such a film can also be used as a viewing angle magnifying film of the present invention.

[8. Use of viewing angle magnifying film: polarizer]

The viewing angle magnifying film of the present invention can be used for the purpose of magnifying the viewing angle of a liquid crystal display device. However, the function of the viewing angle magnifying film of the present invention is not limited to this. For example, the viewing angle magnifying film of the present invention can be used in combination with other functions in addition to its function as a viewing angle magnifying film. Examples of functions other than this viewing angle magnifying 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 described below, it is preferable to use a combination of functions as a protective film for a polarizing plate in a polarizing plate.

The polarizing plate of the present invention includes the viewing angle magnifying film and a polarizer of the present invention. In the polarizing plate of the present invention, the viewing angle magnifying film also has to function as a protective film for the polarizing plate. This polarizing plate can be manufactured, for example, by bonding a polarizer and a viewing angle magnifying film. In the polarizing plate of the present invention, the polarizer and the viewing angle magnifying film may be directly bonded without passing through the bonding layer, or may be bonded through a bonding layer formed of a bonding agent. Furthermore, another protective film may be further interposed between the polarizer and the viewing angle magnifying film.

In the case where the viewing angle magnifying film has a hole-containing portion only on one surface, 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 magnifying film only on one side of the polarizer, or may be provided with a viewing angle magnifying film on both sides. In the case where the viewing angle magnifying film is provided on only one side of the polarizer, the polarizing plate may have any film "that functions as a protective film and is not a viewing angle magnifying film" on the other side of the polarizer.

In the polarizing plate of the present invention, the viewing angle magnifying film must directly contact the polarizer. Or the polarizing plate of the present invention may further have other layers between the viewing angle magnifying film and the polarizer. When the viewing angle magnifying film is in direct contact with the polarizer or only the intermediary adhesive layer, the viewing angle magnifying film has a 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 have a configuration "even if a viewing angle magnifying film is added only to an existing liquid crystal display device". Specifically, a viewing angle magnifying film is placed on the display surface of a liquid crystal display device including various protective elements such as a protective film on the viewing side, compared with the viewing side polarizer. The polarizing plate and the liquid crystal display device of the present invention.

When the polarizing plate of the present invention is used in a VA mode liquid crystal display device described later, it is preferable that the longitudinal direction of the hole-containing portion is parallel to the absorption axis of the polarizer. Thereby, the viewing angle of the VA mode liquid crystal display device can be enlarged.

In addition, when the polarizing plate of the present invention is used in a TN mode liquid crystal display device described later, when the display screen of the liquid crystal display device is viewed from an oblique direction, the angle between the azimuth in which the tone is reversed and the angle between the longitudinal direction including the hole portion is Vertical is preferred. This can enlarge the viewing angle of the TN mode liquid crystal display device.

For example, a polarizer can be manufactured by making a polyvinyl alcohol film adsorb iodine or a dichroic dye and then uniaxially stretching it in a boric acid bath. And, for example, it can also be manufactured by making polyvinyl alcohol film absorb iodine or dichroic dye and extending it, and further modifying a part of the polyvinyl alcohol unit in the molecular chain to polyvinylene )unit. In addition, as the polarizer, for example, a grid polarizer, a multilayer polarizer, a cholesteric liquid crystal polarizer, or the like, a polarizer having a function of separating polarized light into reflected light and transmitted light can also be used. Among them, a polarizer containing polyvinyl alcohol is preferred. The polarization degree of the polarizer is preferably 98% or more, and more preferably 99% or more. The average thickness of the polarizer is preferably 5 μm to 80 μm.

As the bonding agent for bonding the polarizer and the viewing angle magnifying film, any bonding agent that is optically transparent may be used. Examples of the adhesive include water-based adhesives, solvent-based adhesives, two-liquid curing adhesives, ultraviolet-curable adhesives, and pressure-sensitive adhesives. Among them, an aqueous adhesive is preferred, and a polyvinyl alcohol-based aqueous adhesive is more preferred. The bonding agent may be used singly or in combination of two or more kinds in any ratio.

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

There is no limitation on the method of bonding the viewing angle magnifying film and the polarizer, but for example, after applying a bonding agent on one side of the polarizer as required, the polarizer and the viewing angle magnifying film are bonded using a roll laminator, and then dried as required. The method is better. The drying time and drying temperature are appropriately selected depending on the type of the bonding agent.

[9. Liquid crystal display device]

The viewing angle magnifying film of the present invention and the polarizing plate of the present invention can be used in a liquid crystal display device. The liquid crystal cell constituting the liquid crystal display device can use a Twisted Nematic (TN) mode, a Vertical Alignment (VA) mode, an In-Plane Switching (IPS) mode, etc. From the viewpoint of effectively magnifying the viewing angle, the TN mode and the VA mode are preferred.

[9.1. TN mode liquid crystal display device]

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

The TN mode liquid crystal display device of the present invention includes the polarizing plate and the TN mode liquid crystal unit of the present invention in order from the viewing side. The polarizing plate is arranged so that the surface on the viewing angle magnifying film side becomes the viewing side, and the liquid crystal display is viewed from an oblique direction. The azimuth angle of the inversion of the tone in the display screen of the device is perpendicular to the angle between the longitudinal direction of the hole-containing portion. The so-called azimuth angle of the tone inversion here is a polarizing plate having the same structure as the polarizing plate of the present invention except that the viewing angle magnifying film of the present invention is not provided. The azimuth angle of the inversion.

A TN mode liquid crystal display device generally includes 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 disposed on the side opposite to the viewing side, a 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 conventional polarizing plate may be used. Further, as the light source, an arbitrary light source such as a conventional light source may be used.

The viewing side refers to the side on which the observer who displays the image is using the liquid crystal display device.

Generally, when the liquid crystal display device is operated to gradually increase the brightness from black display to white display, the brightness of the display screen also gradually increases. For example, in a case where the display screen of the liquid crystal display device displays 8-bit gray levels (displayed as 0 in black, 255 in white, and mid-tones in the range of 0 to 255), as When the color scale is increased from 0 to 255, the brightness of the display screen is also increased. However, when the operation of gradually increasing the brightness is performed according to the observation direction, the brightness of the display screen may decrease. When the operation of increasing or decreasing the brightness displayed on the display device in this way does not coincide with the increase or decrease of the brightness of the actual display screen, it is called "gradation inversion". When the display screen of the liquid crystal display device is viewed from an oblique direction, a tone inversion may be observed at a certain azimuth angle. In the TN mode liquid crystal display device of the present invention, such a gradation inversion can be reduced by making the azimuth angle of the gradation inversion when the display screen is viewed from an oblique direction perpendicular to the angle between the longitudinal direction of the hole-containing portion. And zoom in.

The azimuth angle of the inversion of the tone is not limited to a single direction, and there are cases where the angle range is bidirectional or spread to a certain degree. In this case, it is necessary to define the direction in which the viewing angle is most enlarged, and then set the longitudinal direction of the hole-containing portion to a direction perpendicular to the direction.

In the TN mode liquid crystal display device of the present invention, it is preferable to use an angle between the absorption axis of the polarizer and the longitudinal direction of the hole-containing portion at 45 ° as the polarizing plate of the present invention. Ordinary TN mode liquid crystal display device (having a rectangular display screen, which is used in a state where the display screen stands upright in the slightly vertical direction, making the longitudinal direction of the rectangle the horizontal direction, and the short side direction the slightly vertical direction) In the middle, it is often observed that the tone is reversed when viewed from the lower side. Moreover, in a normal TN mode liquid crystal display device, the angle between the absorption axis of the polarizer and the horizontal direction of the display screen is usually 45 °. Therefore, in the case where the angle between the absorption axis of the polarizer and the longitudinal direction of the hole-containing portion is 45 ° as the polarizing plate of the present invention, it is easy to perform " 45 ° and the angle between the longitudinal direction of the hole-containing part and the horizontal direction of the display screen is parallel ", so the viewing angle of the TN mode liquid crystal display device can be easily enlarged.

[9.2. VA mode liquid crystal display device]

The viewing angle magnifying film of the present invention or the polarizing plate of the present invention is preferably a liquid crystal display device used in a VA mode.

The liquid crystal display device of the VA mode of the present invention includes the polarizing plate of the present invention and the liquid crystal cell of the VA mode in order from the viewing side. The polarizing plate is arranged such that the surface on the viewing angle magnifying film side becomes the viewing side.

The VA mode liquid crystal display device generally includes 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 disposed on the side opposite to the viewing side, a 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 conventional polarizing plate may be used. Further, as the light source, an arbitrary light source such as a conventional light source may be used.

In the liquid crystal display device of the VA mode of the present invention, it is preferable that a vertical direction including a hole portion is parallel to or perpendicular to the absorption axis of the polarizer as the polarizing plate of the present invention. When such a polarizing plate is arranged in a general liquid crystal display device, the relationship between the vertical direction of the hole-containing portion and the vertical direction of the display screen is preferably parallel or vertical. The longitudinal direction of the hole-containing part must be set to be perpendicular to the "azimuth direction in which the viewing angle is required to be enlarged". For example, in a display device having a rectangular display screen, in a case where the viewing angle in the longitudinal direction is required to be enlarged, the longitudinal direction of the hole-containing portion is preferably arranged in a direction parallel to the short-side direction thereof. The longitudinal direction of the hole-containing portion is usually determined to be a direction parallel to or perpendicular to the absorption axis of the polarizer. With this arrangement, the viewing angle of the VA mode liquid crystal display device can be enlarged.

[Example]

The following examples disclose the present invention. However, the present invention is not limited to the following embodiments, and can be arbitrarily changed and implemented without departing from the scope of the patent application of the present invention and the scope equivalent thereto.

In the following description, unless otherwise specified, the "%" and "parts" of the quantities are based on weight. Unless otherwise specified, the following operations are performed in normal temperature and pressure atmosphere.

[Evaluation method]

(Refractive index of pore-containing layer)

The viewing angle magnifying films obtained in the examples and comparative examples were pressurized until the crack disappeared at an appropriate temperature of Tg or Tm or more and (Tg + 20) ° C or less (Tm + 20) ° C or less of the resin constituting the pore-containing layer. It became transparent, after which the refractive index of the pore-containing layer was measured. A refractive index / film thickness measuring device ("Prism coupler Model 2010 / M" manufactured by AIRIX) was used as a refractive index measuring device.

(Judgment of Crystallinity)

The crystallinity determination object was analyzed using a differential scanning thermal analyzer (DSC) in accordance with JIS K7121 at a temperature rise rate (temperature rise mode) of 10 ° C / min. When there was an endothermic peak, it was determined to be a crystalline resin. .

(Tensile elongation)

A thin film having a thickness of 20 μm as a single layer of the resin to be measured is prepared. Except for Example 1, a film for a core layer having a thickness of 20 mm obtained in the Examples and Comparative Examples was directly used. In Example 1, a product having the same material and a thickness of 20 μm as the biaxially stretched polypropylene film used was obtained. The film was punched into a dumbbell shape as a test piece. For this, the tensile elongation was measured at ISO527-3 (test speed: 50 mm / min).

(White brightness, contrast, and Δγ)

For the liquid crystal display devices of Examples and Comparative Examples, white luminance, contrast, and Δγ were measured.

For the measurement, a spectrometer (manufactured by TOPCON, trade name "SR-LEDW") was used. White brightness and contrast are measured from the front direction (polar angle 0 °) of the display device. During the measurement, the illuminance of the light shining on the display surface of the device was 0 lux. The luminance at the time of white display was determined as the white luminance (unit: cd / m ² ). Then, the ratio of (luminance during white display) / (luminance during black display) was obtained as the contrast. High white brightness indicates good brightness. High contrast means good contrast. A low Δγ indicates that the viewing angle characteristics are good.

In addition, the colors of each tone from 0 (black) to 255 (white) in the gray scale of 256 shades are displayed, and the luminance is viewed from the front direction and the direction at a polar angle of 75 °. The azimuth in the direction with a polar angle of 75 ° is the in-plane direction of the display device perpendicular to the longitudinal direction of the hole-containing portion. In the examples, the in-plane direction of the display device is perpendicular to the longitudinal direction of the hole-containing portion, and in the comparative example, it is the in-plane direction of the display device corresponding to each embodiment. In each direction of observation, the normalized luminance with the luminance in gray level 0 as 0% and the luminance in gray level 255 as 100% is calculated, and the relationship between the gray level and the normalized luminance is calculated. In each tone of the gray scale, the absolute value of the difference between the normalized luminance in the front direction and the normalized luminance in the polar angle of 75 ° is obtained, and the maximum value among these values is obtained as Δγ (%).

[Example 1]

(1-1. Material film)

An unstretched polypropylene film (manufactured by Futamura Chemical Co., Ltd.) having a width of 300 mm and a thickness of 15 μm and a biaxially stretched polypropylene film (manufactured by Futamura Chemical Co., Ltd.) having a thickness of 15 μm were prepared.

The biaxially stretched polypropylene film was used as a determination object, and when the crystallinity of the resin constituting the biaxially stretched polypropylene film was determined, it was crystalline.

When the tensile elongation was measured using a biaxially stretched polypropylene film as a measurement object, the tensile elongation was 5%.

The non-stretched polypropylene film is bonded to the biaxially stretched polypropylene film by a thermal lamination method to obtain a material film.

(1-2. Viewing angle magnifying film)

Production of the viewing angle magnifying film was performed using the apparatuses schematically shown in FIGS. 3 and 4. As the blade 30, a blade made of SUS (tip of the blade R = 0.2 mm) was used in the apparatus.

The material film obtained in (1-1) is arranged such that the side of the non-stretched polypropylene film contacts the blade 30, and the material film 10 is abutted against the blade 30, under a tension of 500 N / m, It was transported in the direction of arrow A11 at a speed of 50 mm / min for crack processing.

During crack processing, the direction of the cutting edge 30E of the insert 30 is set to the width direction (TD direction) of the material film. The angle θ between the center line 30C of the blade 30 and the downstream surface of the material film 10 as viewed from the extension direction of the blade 30E is set to 20 °. Thereby, a viewing angle magnifying film is manufactured.

In the obtained viewing angle magnifying film, a hole-containing portion was found on the side of the biaxially stretched polypropylene film. The hole-containing portion is a substantially linear crack, and the longitudinal directions of the hole-containing portion are approximately parallel to each other, which is approximately parallel to the TD direction of the film. The interval P including the pores is a random interval of 20 μm or less. The average value of the width of each pore-containing portion was 300 nm, the average of the depth of the pore-containing portion was 15 μm, and the average value of the fibril diameter was 20 nm. These values were obtained by selecting any three places of the cracked film and observing an area of 25 μm square with a scanning electron microscope.

For the obtained viewing angle magnifying film, the refractive index of the portion of the biaxially stretched polypropylene film which is a porous layer was measured.

(1-3. Manufacturing of liquid crystal display device)

The viewing angle magnifying film obtained in (1-2) was attached to a polarizing plate on the viewing side surface of a linearly polarized VA mode liquid crystal display device (27-inch model by BenQ, model GW2760HS). When bonding, the angle between the absorption axis of the polarizer in the viewing-side polarizer and the longitudinal direction of the hole-containing portion of the viewing angle magnifying film is 90 °, and the longitudinal direction of the hole-containing portion is parallel to the short side of the rectangular display screen Direction, adjust these directions. In addition, the viewing angle magnifying film is bonded so that the surface on one side of the hole-containing portion is formed as the viewing side. Thereby, the liquid crystal display device of the present invention is obtained.

(1-4. Evaluation)

For the liquid crystal display device obtained in (1-3), white brightness, contrast, and Δγ were measured.

[Example 2]

(2-1. Production of block copolymer [F1])

In a stainless steel reactor equipped with a stirring device that was sufficiently dried and replaced with nitrogen, 256 parts of dehydrated cyclohexane, 25.0 parts of dehydrated styrene and 0.65 parts of di-n-butyl ether were placed, and n-butyl was added while stirring at 60 ° C 0.82 parts of lithium (15% cyclohexane solution) to start polymerization. The reaction was carried out at 60 ° C for 60 minutes while stirring. The polymerization conversion rate at this time point was 99.5%. The reaction temperature was maintained at 60 ° C until the reaction stopped.

Next, it took 150 minutes to continuously add 50 parts of a mixed monomer composed of 25 parts of a styrene monomer and 25 parts of an isoprene monomer to the reaction solution, and after the addition was completed, stirring was continued for 20 minutes. The polymerization conversion rate at this time point was 99.5%. After that, 25.0 parts of dehydrated styrene was further added and stirred for 60 minutes. The polymerization conversion rate at this time point was almost 100%. Next, 0.5 part of isopropyl alcohol was added to the reaction solution to stop the reaction, and a polymerization reaction solution containing the block copolymer [F1] was obtained. The weight average molecular weight (Mw) of the obtained block copolymer [F1] was 58,000, and the molecular weight distribution (Mw / Mn) was 1.03.

(2-2. Production of hydrogenated block copolymer [G1])

Transfer the polymerization reaction solution obtained in (2-1) to a pressure-resistant reactor equipped with a stirring device, and add and mix the silica-alumina-supported nickel catalyst (E22U, nickel bearing capacity 60%) as a hydrogenation catalyst; 4.0 parts by Niwa Chemical Industry Co., Ltd. and 350 parts of dehydrated cyclohexane. The inside of the reactor was replaced with hydrogen, and hydrogen was supplied while stirring the solution, and a hydrogenation reaction was performed at a temperature of 170 ° C. and a pressure of 4.5 MPa for 6 hours.

After the hydrogenation reaction is completed, the reaction solution is filtered to remove the hydrogenation catalyst. To the filtrate, pentaerythrityl tetrakis [3- (3,3,5-di-tert-butyl-4-hydroxyphenyl) propanoic acid] neopenta [3- (3 , 5-di- t- butyl-4-hydroxyphenyl) propionate], trade name "AO60", manufactured by ADEKA Corporation) 0.1 part of xylene solution 1.0 part, and dissolved.

Next, the above-mentioned solution was treated at a temperature of 260 ° C and a pressure of 0.001 MPa or less using a cylindrical concentration dryer (manufactured by Hitachi, Ltd., trade name "KONTRO"), and cyclohexane, xylene, and Other volatile components give a molten resin. A polymer filter (manufactured by Fuji Filter) equipped with a sintered stainless steel filter having a pore size of 20 μm connected to a concentrating dryer was filtered at a temperature of 260 ° C, and the molten polymer was extruded from a mold into a bar. It is cooled and shaped into pellets by a granulator. Thereby, pellets of the resin [G1] containing the hydrogenated block copolymer [G1] were obtained.

The hydrogenated block copolymer [G1] in the obtained resin [G1] is a block in which St, a repeating unit derived from styrene, and a repeating unit derived from isoprene coexist (hereinafter, referred to as "St / Ip ") and a ternary block copolymer made of Ip, the weight ratio of each block is St: St / Ip: St = 25: 25/25: 25. The block copolymer had a Mw of 59,000, a Mw / Mn of 1.05, a hydrogenation rate of almost 100%, and a thermal softening temperature Ts of 110 ° C.

(2-3. Production of block copolymer [F2])

In a reactor equipped with a stirring device and sufficiently replaced with nitrogen inside, 270 parts of dehydrated cyclohexane, 75 parts of dehydrated styrene, and 7.0 parts of di-n-butyl ether were placed. While stirring the entire container at 60 ° C, 5.6 parts of n-butyllithium (15% cyclohexane solution) was added to start polymerization. Next, the entire container was stirred at 60 ° C for 60 minutes. The reaction temperature was maintained at 60 ° C until the reaction stopped.

The polymerization conversion rate at this time point (the first stage of polymerization) was 99.4%.

Next, it took 40 minutes to continuously add 15 parts of dehydrated isoprene to the reaction solution. After the addition, the stirring was continued for 30 minutes. The polymerization conversion rate at this time point (the second stage of polymerization) was 99.8%.

After that, it further took 30 minutes, and 10 parts of dehydrated styrene was continuously added to the reaction solution, and after the addition was completed, it was stirred for 30 minutes. The polymerization conversion rate at this time point (the third stage of polymerization) was almost 100%.

Here, 1.0 part of isopropyl alcohol was added to stop the reaction to obtain a polymer solution containing a block copolymer [D1]-[E]-[D2] type [F2]. In the obtained block copolymer [F2], Mw [F2] = 82,400, Mw / Mn was 1.32, and wA: wB = 85: 15.

(2-4. Production of hydrogenated block copolymer [G2])

The polymer solution obtained in (2-3) was transferred to a pressure-resistant reactor equipped with a stirring device, and a diatomite-supported nickel catalyst (trade name "E22U") was added and mixed as a hydrogenation catalyst, and the nickel bearing capacity was 60. %, Manufactured by Nihon Catalyst Chemical Co., Ltd.) 4.0 parts and dehydrated cyclohexane 30 parts. The inside of the reactor was replaced with hydrogen, and hydrogen was supplied while stirring, and a hydrogenation reaction was performed at a temperature of 190 ° C and a pressure of 4.5 MPa for 6 hours.

The reaction solution obtained by the hydrogenation reaction contains a hydrogenated block copolymer [G2]. The Mw [G2] of the hydrogenated block copolymer [G2] was 71,800, the molecular weight distribution Mw / Mn was 1.30, and the hydrogenation rate was almost 100%.

After the hydrogenation reaction was completed, the reaction solution was filtered to remove the hydrogenation catalyst, and then [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid], which is a phenol-based antioxidant, was added. Neopentyl tetrakis (pentaerythrityl tetrakis [3- (3,5-di- t- butyl-4-hydroxyphenyl) propionate], trade name "AO60", manufactured by ADEKA) 2.0 parts xylene solution 2.0 parts Dissolve.

Next, the above solution was treated at a temperature of 260 ° C and a pressure of 0.001 MPa or less using a cylindrical concentrator dryer (brand name "KONTRO", manufactured by Hitachi, Ltd.) to remove cyclohexane, xylene, and other volatile components from the solution. To obtain a molten resin. It is extruded from a die into a bar shape, cooled, and formed into pellets by a pelletizer. Thereby, 95 parts of pellets of the resin [G2] containing the hydrogenated block copolymer [G2] were produced.

The hydrogenated block copolymer [G2] in the obtained resin [G2] had Mw [G2] = 68,500, Mw / Mn = 1.30, and Ts = 139 ° C.

When the resin [G2] is used as the determination object, the crystallinity is determined to be amorphous.

When the tensile elongation was measured using the resin [G2] as a measurement object, the tensile elongation was 4%.

(2-5. Preparation of material film)

As a material film, a multilayer film composed of a two-layer, three-layer layer including a surface layer, a core layer, and a surface layer is formed. For forming, a film forming apparatus for co-extrusion is used. The resin [G1] obtained in (2-2) was used as the material of the surface layer. The resin [G2] obtained in (2-4) was used as the material of the core layer.

The obtained material film has a width of 300 mm, the thickness of each surface layer is 10 μm, the thickness of the core layer is 20 μm, and the thickness of the entire material film is 40 μm.

(2-6. Manufacturing of viewing angle magnifying film)

Manufacturing of the viewing angle magnifying film is performed using the apparatuses schematically shown in FIGS. 3 and 4. As the blade 30, a blade made of SUS (tip of the blade R = 0.2 mm) was used in the apparatus.

Configure the material film obtained in (2-5) such that one side of the material film contacts the blade 30, and place the material film 10 against the blade 30 under a tension of 450 N / m at a speed of 50 mm / min. It is transported in the direction of arrow A11 for crack processing.

During crack processing, the direction of the cutting edge 30E of the insert 30 is set to the width direction (TD direction) of the material film. The angle θ between the center line 30C of the blade 30 and the downstream surface of the material film 10 as viewed from the extension direction of the blade 30E is set to 20 °. Thereby, a viewing angle magnifying film is manufactured.

In the obtained viewing angle magnifying film, a hole-containing portion was found in the core layer. The hole-containing portion is a substantially linear crack, and the longitudinal directions of the hole-containing portion are approximately parallel to each other, which is approximately parallel to the TD direction of the film. The interval P including the pores is a random interval of 1.2 μm or less. The average value of the width of each pore-containing portion was 250 nm, the average of the depth of the pore-containing portion was 20 μm, and the average diameter of the fibril fibers was 5 nm. These values were obtained by selecting any three places of the cracked film and observing an area of 25 μm square with a scanning electron microscope.

The refractive index of the hole-containing layer was measured for the obtained viewing angle magnifying film. Because the pore-containing layer is the core layer, in the measurement of the refractive index of the pore-containing layer, the refractive index of the core layer is measured.

(2-7. Manufacturing of liquid crystal display device)

The polarizing plate on the viewing side surface of the linearly polarized VA mode liquid crystal display device (the same as that used in (1-3) of Example 1) was bonded to the viewing angle magnifying film obtained in (2-6). When bonding, the angle between the absorption axis of the polarizer in the viewing side polarizer and the longitudinal direction of the hole-containing portion of the viewing angle magnifying film is 90 °, and the longitudinal direction of the hole-containing portion is parallel to the short length of the rectangular display screen. Side direction, adjust these directions. Thereby, the liquid crystal display device of the present invention is obtained.

(2-8. Evaluation)

For the liquid crystal display device obtained in (2-7), white brightness, contrast, and Δγ were measured.

[Example 3]

A liquid crystal display device and its constituent elements were obtained and evaluated by the same operations as in Example 2 except for the following changes. (2-6) In the production of the viewing angle magnifying film, the blade made of SUS was changed from the tip R = 0.2 mm to the tip R = 0.5 mm. l (2-6) In the production of the viewing angle magnifying film, the tension of the material film was changed from 450 N / m to 300 N / m.

In the viewing angle magnifying film obtained in Example 3, a hole-containing portion was found in the core layer. The hole-containing portion is a substantially straight crack, and the longitudinal directions of the hole-containing portion are approximately parallel to each other, which is approximately parallel to the TD direction of the film. The interval P including the pores is a random interval of 1.8 μm or less. The average value of the width of each pore-containing portion is 50 nm, the average of the depth of the pore-containing portion is 20 μm, and the average value of the fibril diameter is 5 nm. In the measurement of the refractive index of the pore-containing layer, the refractive index of the core layer is measured.

[Example 4]

(4-1. Preparation of material film)

As a material film, a multilayer film composed of a two-layer, three-layer layer including a surface layer, a core layer, and a surface layer was formed. For forming, a film forming apparatus for co-extrusion is used. As the material of the surface layer, an acrylic resin (“HT55X” manufactured by Sumitomo Chemical Co., Ltd., with a glass transition temperature of 108 ° C.) containing an acrylic polymer and rubber particles was used. As a material of the core layer, a polymethyl acrylate polymer resin (trade name "DELPET 80NH" manufactured by Asahi Kasei Corporation, glass transition temperature of 102 ° C) was used.

The obtained material film has a width of 300 mm, the thickness of each surface layer is 10 μm, the thickness of the core layer is 20 μm, and the thickness of the entire material film is 40 μm.

When the polymethyl acrylate polymer resin is used as a determination object, the crystallinity is determined to be amorphous.

When the polymethyl acrylate polymer resin was used as a measurement object to measure the tensile elongation, the tensile elongation was 5%.

(4-2. Manufacturing and evaluation of viewing angle magnifying film and liquid crystal display device)

A liquid crystal display device and its constituent elements were obtained and evaluated by the same operations as (2-6) to (2-8) of Example 2 except for the following changes. l In the production of the viewing angle magnifying film of (2-6), the material film obtained in (4-1) is used instead of the material film obtained in (2-5).

In the viewing angle magnifying film obtained in Example 4, a hole-containing portion was found in the core layer. The pore-containing portion is a substantially linear crack, and the longitudinal directions of the pore-containing portion are approximately parallel to each other, and approximately parallel to the TD direction of the film. The interval P including the pores is a random interval of 1.2 μm or less. The average value of the width of each pore-containing portion was 50 nm, the average value of the depth of the pore-containing portion was 19 μm, and the average diameter of the fibril fibers was 5 nm. In the measurement of the refractive index of the pore-containing layer, the refractive index of the core layer is measured.

[Example 5]

(5-1. Preparation of material film)

As a material film, a multilayer film composed of a two-layer, three-layer layer including a surface layer, a core layer, and a surface layer was formed. For forming, a film forming apparatus for co-extrusion is used. As the material of the surface layer, a norbornene-based polymer 1 (trade name: ZEONOR 1600, manufactured by Japan Rui Weng Co., Ltd., glass transition temperature: 163 ° C.) was used. As the material of the core layer, a norbornene-based polymer 2 (trade name: ZEONEX K26R, manufactured by Japan Rui Weng Co., Ltd., glass transition temperature: 143 ° C) was used.

The obtained material film has a width of 300 mm, the thickness of each surface layer is 10 μm, the thickness of the core layer is 20 μm, and the thickness of the entire material film is 40 μm.

When crystallinity is determined by using a norbornene-based polymer 2 (ZEONEX K26R) as a determination object, it is amorphous.

When the tensile elongation was measured using a norbornene polymer 2 (ZEONEX K26R) as a measurement object, the tensile elongation was 2%.

(5-2. Manufacturing and evaluation of viewing angle magnifying film and liquid crystal display device)

A liquid crystal display device and its constituent elements were obtained and evaluated by the same operations as (2-6) to (2-8) of Example 2 except for the following changes. l In the production of the viewing angle magnifying film of (2-6), the material film obtained in (5-1) is used instead of the material film obtained in (2-5). l (2-6) In the production of the viewing angle magnifying film, the tension of the material film was changed from 450 N / m to 700 N / m.

In the viewing angle magnifying film obtained in Example 5, a hole-containing portion was found in the core layer. The pore-containing portion is a substantially linear crack, and the longitudinal directions of the pore-containing portion are approximately parallel to each other, and approximately parallel to the TD direction of the film. The interval P containing pores is a random interval of 1.5 μm or less. The average value of the width of each pore-containing portion was 45 nm, the average of the depth of the pore-containing portion was 19 μm, and the average diameter of the fibril fibers was 5 nm. In the measurement of the refractive index of the pore-containing layer, the refractive index of the core layer is measured.

[Comparative Example 1]

For the liquid crystal display devices in Examples 1 to 5, white luminance, contrast, and Δγ were measured.

[Comparative Example 2]

(C2-1. Preparation of material film)

As a material film, a multilayer film composed of a two-layer, three-layer layer including a surface layer, a core layer, and a surface layer was formed. For forming, a film forming apparatus for co-extrusion is used. As the material of the surface layer, an acrylic resin (“HT55X” manufactured by Sumitomo Chemical Co., Ltd., with a glass transition temperature of 108 ° C.) containing an acrylic polymer and rubber particles was used. As a material of the core layer, a styrene-maleic anhydride copolymer resin ("Dylark D332" manufactured by Nova Chemicals, glass transition temperature of 128 ° C) was used.

The obtained material film has a width of 300 mm, the thickness of each surface layer is 10 μm, the thickness of the core layer is 20 μm, and the thickness of the entire material film is 40 μm.

When the styrene-maleic anhydride copolymer resin is used as a determination object, the crystallinity is determined to be amorphous.

When the tensile elongation was measured using a styrene-maleic anhydride copolymer resin as a measurement object, the tensile elongation was 2%.

(C2-2. Manufacturing and evaluation of viewing angle magnifying films and liquid crystal display devices)

A liquid crystal display device and its constituent elements were obtained and evaluated by the same operations as (2-6) to (2-8) of Example 2 except for the following changes. l In the production of the viewing angle magnifying film (2-6), the material film obtained in (C2-1) is used in place of the material film obtained in (2-5). l (2-6) In the manufacture of the viewing angle magnifying film, the tension of the material film was changed from 450 N / m to 500 N / m.

In the viewing angle magnifying film obtained in Comparative Example 2, a hole-containing portion was found in the core layer. The pore-containing portion is a substantially linear crack, and the longitudinal directions of the pore-containing portion are approximately parallel to each other, and approximately parallel to the TD direction of the film. The interval P including the pores is a random interval of 1.2 μm or less. The average value of the width of each pore-containing portion was 50 nm, the average value of the depth of the pore-containing portion was 19 μm, and the average diameter of the fibril fibers was 5 nm. In the measurement of the refractive index of the pore-containing layer, the refractive index of the core layer is measured.

[Comparative Example 3]

(C3-1. Preparation of material film)

As a material film, a multilayer film composed of a two-layer, three-layer layer including a surface layer, a core layer, and a surface layer was formed. For forming, a film forming apparatus for co-extrusion is used. As the material of the surface layer, a polycarbonate resin (trade name "Panlite AD5503", manufactured by Teijin Co., Ltd., glass transition temperature: 142 ° C) was used. As the material of the core layer, another polycarbonate resin (trade name "IUPILON HL8004", manufactured by Mitsubishi Engineering Plastics, Inc., glass transition temperature of 136 ° C) was used.

The obtained material film has a width of 300 mm, the thickness of each surface layer is 10 μm, the thickness of the core layer is 20 μm, and the thickness of the entire material film is 40 μm.

When the styrene-maleic anhydride copolymer resin is used as a determination object, the crystallinity is determined to be amorphous.

When the tensile elongation was measured using a styrene-maleic anhydride copolymer resin as a measurement object, the tensile elongation was 2%.

(C3-2. Manufacturing and evaluation of viewing angle magnifying film and liquid crystal display device)

A liquid crystal display device and its constituent elements were obtained and evaluated by the same operations as (2-6) to (2-8) of Example 2 except for the following changes. l In the production of the viewing angle magnifying film (2-6), the material film obtained in (C3-1) is used instead of the material film obtained in (2-5). (2-6) In the production of the viewing angle magnifying film, the tension of the material film was changed from 450 N / m to 700 N / m.

In the viewing angle magnifying film obtained in Comparative Example 3, a hole-containing portion was found in the core layer. The pore-containing portion is a substantially linear crack, and the longitudinal directions of the pore-containing portion are approximately parallel to each other, and approximately parallel to the TD direction of the film. The interval P containing pores is a random interval of 1.5 μm or less. The average value of the width of each pore-containing portion was 40 nm, the average value of the depth of the pore-containing portion was 19 μm, and the average diameter of the fibril fibers was 5 nm. In the measurement of the refractive index of the pore-containing layer, the refractive index of the core layer is measured.

The results of the examples and comparative examples are summarized in Table 1.

[Table 1]

From the results shown in Table 1, it is clear that in the examples using the "view-angle magnifying film made of a material that satisfies the requirements such as the refractive index of the present invention", excellent characteristics with a contrast ratio of more than 2000 and Δγ of 20 or less can be obtained Liquid crystal display device.

1‧‧‧ viewing angle magnifying film

10‧‧‧ film

20‧‧‧ with holes

21‧‧‧ Crack (including hole)

211‧‧‧fibril

212‧‧‧Gap

100‧‧‧Crack processing device

30‧‧‧ Blade

FIG. 1 is a plan view schematically showing an example of a viewing angle magnifying film. FIG. 2 is an enlarged schematic diagram showing an example of a crack structure. FIG. 3 is a perspective view schematically showing an example of a crack processing device. FIG. 4 is a side view schematically showing the vicinity of the blade of FIG. 3 in an enlarged manner.

Claims (12)

A viewing angle enlarging film is a viewing angle enlarging film for enlarging a viewing angle. The viewing angle enlarging film includes more than one resin layer; more than one layer of the resin layer is a pore-containing layer; the pore-containing layer has a plurality of approximately parallel to each other. The pore-containing portions include pores; the pore-containing layer has a refractive index of 1.53 or less. The viewing angle magnifying film according to claim 1, wherein the resin constituting the pore-containing layer is an amorphous resin. The viewing angle magnifying film according to claim 1, comprising the resin layer of two or more layers. The viewing angle magnifying film according to claim 1, wherein the interval between the adjacent pore-containing portions is a random interval of 50 μm or less. The viewing angle magnifying film according to claim 1, further comprising an ultraviolet absorber. The viewing angle magnifying film according to claim 1, wherein the viewing angle magnifying film is a polarizing plate protective film. The viewing angle magnifying film according to any one of claims 1 to 6, wherein the hole-containing portions include a crack. A polarizing plate comprising the viewing angle magnifying film and a polarizer according to any one of claims 1 to 7. The polarizing plate according to claim 8, wherein the longitudinal direction of the hole-containing portions is parallel to or perpendicular to the absorption axis of the polarizer. The polarizing plate according to claim 8, wherein an included angle between the absorption axis of the polarizer and the longitudinal direction of the hole-containing portions is 45 °. A twisted nematic (TN) mode liquid crystal display device is a TN mode liquid crystal display device sequentially provided with a polarizing plate as described in claim 8 or 9 and a TN mode liquid crystal cell from a viewing side. The polarizing plate is The side of the viewing angle magnifying film disposed on the polarizing plate is the viewing side; when the display screen is viewed from an oblique direction, the included angle of the azimuth inversion of the tone is perpendicular to the longitudinal direction of the hole-containing portions. A vertical alignment (VA) mode liquid crystal display device is a VA mode liquid crystal display device provided with a polarizing plate as described in claim 8 or 9 and a VA mode liquid crystal cell in order from a viewing side. The polarizing plate is configured. The surface forming the viewing angle magnifying film of the polarizing plate is the viewing side.