JP2017191334A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device that can solve the problem of light leakage due to warpage of liquid crystal cells generated when the liquid crystal display device is lighted on after storage under a high-humidity environment.SOLUTION: An optical film is composed of acrylic resin, where tensile elasticity in a machine direction (MD direction) and tensile elasticity in a direction orthogonal to the machine direction (TD direction) satisfy the relationship of the formula (1): (the tensile elasticity in the MD direction)/(the tensile elasticity in the TD direction)>1.36.SELECTED DRAWING: None

Description

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

  Liquid crystal display devices are increasingly used year by year as space-saving image display devices with low power consumption. Wide viewing angle liquid crystal modes such as VA mode and IPS mode have been put into practical use, and as a result, the demand for liquid crystal display devices is rapidly expanding even in markets where high-quality images such as televisions are required.

  In addition, as the application of liquid crystal display devices is expanded, large-sized and high-quality textures are required for liquid crystal display devices. On the other hand, when the size is increased, the liquid crystal display device becomes heavy. In order to reduce the weight, the thickness of various members has been reduced.

  The liquid crystal display device includes a liquid crystal cell and a polarizing plate provided on the viewing side (front side) and the backlight side (rear side) of the liquid crystal cell. Both polarizing plates are attached to the substrates on both sides of the liquid crystal cell with an adhesive or the like. A polarizing plate used in a liquid crystal display device generally has a configuration in which a polarizer made of a polyvinyl alcohol (PVA) film or the like on which iodine or a dye is adsorbed and oriented, and a transparent protective film are bonded to both sides of the polarizer. However, since PVA is hydrophilic, the polarizer is sensitive to changes in temperature and humidity, and easily expands and contracts due to changes in the surrounding environment. When the polarizer expands and contracts, the polarizing plate (laminate of the optical film containing the polarizer) expands and contracts, warping occurs in the liquid crystal cell to which the optical plate is attached, and display unevenness (at the four corners of the liquid crystal cell) Resulting in light leakage). With recent reduction in thickness of various members, light leakage due to warpage of the liquid crystal cell has become apparent.

International Publication No. 2009/047924

From the viewpoint of ensuring transparency and adhesion with PVA used in a polarizer, a cellulose acylate polarizing plate protective film is widely used because it can easily ensure adhesion with PVA used in a polarizer. In recent years, however, the use of a polarizing plate protective film made of an acrylic resin has been studied. Since an acrylic film made of an acrylic resin has a lower moisture content than a cellulose acylate film, it is expected that the expansion and contraction of the polarizing plate due to the entry and exit of water (change in humidity) can be reduced. Patent Document 1 discloses a polarizing plate protective film made of an acrylic resin. However, it was found that even in the polarizing plate protective film made of this acrylic resin, the moisture content is still high with respect to the performance of reducing the shrinkage of the polarizing plate, and the expansion and contraction of the polarizing plate is still large.
Since the moisture content of the film comprised only by acrylic resin is about 1% (25 degreeC relative humidity 60%), the present inventors think that there exists an improvement effect in the expansion-contraction of a polarizing plate, and consist of the said film. The examination using a polarizing plate protective film was performed. As a result, it was found that the moisture content was lower than that of the polarizing plate protective film disclosed in JP2012-08417A, and the expansion and contraction of the polarizing plate could be reduced. However, even with the above film, the expansion and contraction of the polarizing plate cannot be sufficiently suppressed, and the warp of the liquid crystal cell has not been sufficiently solved.

  The problem to be solved by the present invention is to provide an optical film that can solve the problem of light leakage due to warping of a liquid crystal cell that occurs when the lamp is lit after storage in a high humidity environment.

According to the study by the present inventors, the value of the ratio obtained by dividing the tensile elastic modulus in the machine direction (MD direction) of the acrylic film made of acrylic resin by the tensile elastic modulus in the direction perpendicular to the machine direction (TD direction). By making the value larger than 1.36, the warpage of the liquid crystal cell can be greatly reduced, and as a result, it has been found that light leakage can be remarkably improved, and the present invention has been completed.
That is, the above problem can be solved by the following means.
<1>
A liquid crystal display device comprising at least a front-side polarizing plate, a liquid crystal cell, and a rear-side polarizing plate,
The polarizing plate on the front side is a polarizer and at least one side of the polarizer,
An optical film having a thickness of 10 to 40 μm made of an acrylic resin and satisfying the relationship of the formula (1) in the tensile modulus in the machine direction (MD direction) and the tensile modulus in the direction perpendicular to the machine direction (TD direction) Comprising
The liquid crystal display device in which the mechanical direction (MD direction) of the optical film of the front-side polarizing plate is parallel to the direction of the long side of the display surface of the liquid crystal display device.
Formula (1) Tensile modulus in MD direction / Tension modulus in TD direction> 1.36
<2>
The tensile elastic modulus in the machine direction (MD direction) of the optical film is 1.70 × 10 ^{9 to} 5.5 × 10 ⁹ N / m ² , and the tensile elastic modulus in the direction perpendicular to the machine direction (TD direction) is The liquid crystal display device according to <1>, which is 1.2 × 10 ^{9 to} 4.0 × 10 ⁹ N / m ² .
<3>
<1> or <1 < The liquid crystal display device according to 2>.
(I) Re = (nx−ny) × d
(Ii) Rth = ((nx + ny) / 2−nz) × d
(Iii) 0 ≦ Re <20
(Iv) | Rth | ≦ 25
In the formula, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is the film (Nm).
<4>
At least one layer of a pattern retardation layer, a λ / 4 layer, an optically anisotropic layer, a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an easy adhesion layer is provided on the surface of the optical film <1. The liquid crystal display device according to any one of> to <3>.
<5>
The rear polarizing plate is a polarizer and at least on one side of the polarizer,
Comprising the optical film,
The liquid crystal display device according to any one of <1> to <4>, wherein a mechanical direction (MD direction) of the optical film of the rear polarizing plate is parallel to a direction of a short side of the liquid crystal display device.
<6>
The optical film is provided on both surfaces of the polarizer of the front-side polarizing plate,
The liquid crystal display device according to any one of <1> to <5>, wherein a mechanical direction (MD direction) of the optical film is parallel to a direction of a long side of the liquid crystal display device.
<7>
The optical film is provided on both sides of the polarizer of the rear side polarizing plate,
The liquid crystal display device according to <5> or <6>, wherein a mechanical direction (MD direction) of the optical film is parallel to a direction of a short side of the liquid crystal display device.
<8>
The liquid crystal display device according to any one of <1> to <7>, wherein the polarizer and the optical film are bonded with a curable adhesive.
<9>
The liquid crystal display device according to any one of <1> to <8>, wherein the liquid crystal cell is in an IPS mode or a VA mode.
Although this invention is invention which concerns on said <1>-<9>, below, other matters are also described.

[1]
An optical film made of an acrylic resin, wherein the tensile elastic modulus in the machine direction (MD direction) and the tensile elastic modulus in the direction perpendicular to the machine direction (TD direction) satisfy the relationship of formula (1).
Formula (1) Tensile modulus in MD direction / Tension modulus in TD direction> 1.36
[2]
The tensile modulus in the machine direction (MD direction) of the optical film is 1.70 × 10 ^{9 to} 5.5 × 10 ⁹ N / m ² , and the tensile modulus in the direction perpendicular to the machine direction (TD direction) is The optical film according to [1], which is 1.2 × 10 ^{9 to} 4.0 × 10 ⁹ N / m ² .
[3]
The retardation value Re in the film plane and the retardation value Rth in the film thickness direction represented by the formulas (i) and (ii) of the optical film satisfy the formulas (iii) and (iv) [1] or [ 2].
(I) Re = (nx−ny) × d
(Ii) Rth = ((nx + ny) / 2−nz) × d
(Iii) 0 ≦ Re <20
(Iv) | Rth | ≦ 25
In the formula, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is the film (Nm).
[4]
At least one layer of a pattern retardation layer, a λ / 4 layer, an optically anisotropic layer, a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an easy adhesion layer is provided on the surface of the optical film [1. ] The optical film in any one of [3].
[5]
The polarizing plate which has a polarizer and the optical film in any one of [1]-[4] on the single side | surface of a polarizer at least.
[6]
The polarizing plate as described in [5] which has the optical film in any one of [1]-[4] on both surfaces of a polarizer.
[7]
A liquid crystal display device having at least one polarizing plate according to [5] or [6].

Hereinafter, means for solving the problems of the present invention will be described in more detail.
By stretching the film in the machine direction (MD direction), the molecular orientation of the resin increases and the tensile elastic modulus in the MD direction of the film increases. On the other hand, the humidity dimensional change rate in the MD direction is reduced by increasing the molecular orientation of the resin. The present inventors presume that this is because water does not easily enter between molecules in the MD direction, and the effect of reducing the substantial water content is also exhibited. In addition, the present inventors determined that the force generated by the expansion and contraction of the polarizing plate is determined by the product of the film thickness of the polarizing plate and the film thickness of the polarizer, the tensile elastic modulus, and the dimensional change rate. It has been found that the expansion and contraction of the polarizing plate can be effectively suppressed by designing the product of the film thickness, tensile elastic modulus, and dimensional change rate of the film. An increase in tensile elastic modulus works in a direction to increase the stretching force of the optical film, and a reduction in dimensional change rate works in a direction to weaken the stretching force of the optical film. When a film made of an acrylic resin is stretched in the MD direction, the effect of reducing the dimensional change rate of the optical film in the MD direction is greater than the effect of increasing the tensile elastic modulus of the optical film in the MD direction. The force generated by the expansion and contraction of the plate can be weakened. On the other hand, when the film is stretched in the MD direction, the force generated by the expansion and contraction of the polarizing plate in the direction perpendicular to the MD direction (TD direction) becomes stronger. Here, it is known that the liquid crystal cell tends to warp in the longitudinal direction.
Usually, in a liquid crystal display device, the polarizers are arranged in a crossed Nicol arrangement, so the longitudinal direction of the front polarizing plate corresponds to the MD direction of the film, and the longitudinal direction of the rear polarizing plate corresponds to the TD direction of the film. Due to the difference between the force generated by the expansion and contraction of the front-side polarizing plate and the force generated by the expansion and contraction of the rear-side polarizing plate, the liquid crystal cell is warped. By using an optical film stretched in the MD direction, The present inventors presume that the amount of warpage of the liquid crystal cell can be reduced by combining the side polarizing plate and the rear side polarizing plate. In addition, when an acrylic film having a ratio of tensile modulus in the MD direction / tensile modulus in the TD direction is greater than 1.36, a conventional acrylic film (the ratio of the tensile modulus is about 1.08 at the maximum) is used. As compared with the case of using the liquid crystal display device, the display unevenness of the liquid crystal display device caused by the warp of the liquid crystal cell can be clearly reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal display device which eliminated the problem of the light leakage based on the curvature of the liquid crystal cell which generate | occur | produces when it lightes after the preservation | save in a high-humidity environment can be provided.

  The optical film of the present invention is made of an acrylic resin.

The acrylic resin is a concept including a methacrylic resin, and includes acrylate / methacrylate derivatives, in particular, acrylate ester / methacrylate ester (co) polymers.
Further, the acrylic resin includes, in addition to the methacrylic resin, an acrylic resin having a ring structure in the main chain, a polymer having a lactone ring, a maleic anhydride polymer having a succinic anhydride ring, and an anhydrous glutar It includes a polymer having an acid ring and a glutarimide ring-containing polymer.
Further, “consisting of acrylic resin” means that the optical film contains 70% by mass or more of acrylic resin, preferably 80% by mass or more of acrylic resin, and more preferably 90% by mass of acrylic resin. Including at least%.

(Acrylic resin)
The repeating structural unit of the acrylic resin is not particularly limited. The acrylic resin preferably has a repeating structural unit derived from an acrylate monomer as a repeating structural unit.

The acrylate ester is not particularly limited, and examples thereof include acrylate esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, and benzyl acrylate. Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate and benzyl methacrylate; You may use only a seed | species and may use 2 or more types together. Among these, methyl methacrylate is particularly preferable from the viewpoint of excellent heat resistance and transparency.
When the acrylate ester is used as a main component, the content ratio in the monomer component to be subjected to the polymerization step is preferably 50 to 100% by mass, more preferably 70, in order to sufficiently exhibit the effects of the present invention. -100 mass%, More preferably, it is 80-100 mass%, Most preferably, it is 90-100 mass%.
It is preferable that the glass transition temperature Tg of the resin mainly composed of the acrylate ester is in the range of 80 to 120 ° C.
The weight average molecular weight of the resin mainly composed of the acrylate ester is preferably in the range of 50,000 to 500,000.

-Acrylic resin with a ring structure in the main chain-
Among acrylic resins, those having a ring structure in the main chain are preferred. By introducing a ring structure into the main chain, the rigidity of the main chain can be improved and the heat resistance can be improved.
In the present invention, among acrylic resins having a ring structure in the main chain, a polymer containing a lactone ring structure in the main chain, a maleic anhydride polymer having a succinic anhydride ring in the main chain, and a glutaric anhydride ring in the main chain It is preferably either a polymer having a structure or a polymer having a glutarimide ring structure in the main chain. Among them, a polymer having a lactone ring structure in the main chain and a polymer having a glutarimide ring structure in the main chain are more preferable.
The following polymers having a ring structure in these main chains will be described in order.

(1) Acrylic resin having a lactone ring structure in the main chain An acrylic resin having a lactone ring structure in the main chain (hereinafter also referred to as a lactone ring-containing polymer) is an acrylic resin having a lactone ring in the main chain. Although it does not specifically limit, Preferably it has a lactone ring structure shown by the following general formula (100).

  Formula (100):

In General Formula (100), R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms, and the organic residue may contain an oxygen atom. .
Here, the organic residue having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 6 carbon atoms, specifically, a methyl group, an ethyl group, an isopropyl group, an n-butyl group, or a t-butyl group. Etc. are preferable.

  The content ratio of the lactone ring structure represented by the general formula (100) in the structure of the lactone ring-containing polymer is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 60% by mass. %, Particularly preferably 10 to 50% by mass. By setting the content ratio of the lactone ring structure to 5% by mass or more, the heat resistance and surface hardness of the obtained polymer tend to be improved, and by setting the content ratio of the lactone ring structure to 90% by mass or less. The moldability of the obtained polymer tends to be improved.

The content ratio of the lactone ring structure can be calculated from the following formula.
Lactone ring content (% by mass) = B × A × M _R / M _m
(Wherein, B is the mass proportion in the monomer composition used in the copolymerization raw monomer having a structure (hydroxyl group) responsible for the lactonization, M _R lactone ring structure to generate The unit formula weight, M _m is the molecular weight of the raw material monomer having a structure (hydroxyl group) involved in lactone cyclization, and A is the lactone cyclization rate)
In addition, when the cyclization reaction involves a dealcoholization reaction, for example, the lactone cyclization rate can be determined by removing the theoretical weight loss from 150 ° C. before the weight reduction starts to 300 ° C. before the polymer decomposition starts. It can be calculated from the weight loss heating weight loss rate due to the alcohol reaction.

There is no particular limitation on the method for producing the acrylic resin having a lactone ring structure. Preferably, the acrylic resin having a lactone ring structure was obtained after obtaining the polymer (p) having a hydroxyl group and an ester group in the molecular chain by polymerizing the following predetermined monomer: The polymer (p) is obtained by subjecting the polymer (p) to heat treatment at a temperature range of 75 ° C. to 120 ° C. to perform lactone cyclization condensation for introducing a lactone ring structure into the polymer.
In the polymerization step, a polymer having a hydroxyl group and an ester group in the molecular chain is obtained by performing a polymerization reaction of a monomer component containing a monomer represented by the following general formula (101).
Formula (101):

(In the formula, R ¹ and R ² each independently represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms.)

  Examples of the monomer represented by the general formula (101) include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, 2- ( Hydroxymethyl) normal butyl acrylate, 2- (hydroxymethyl) acrylate t-butyl and the like. Among these, methyl 2- (hydroxymethyl) acrylate and 2- (hydroxymethyl) ethyl acrylate are preferable, and methyl 2- (hydroxymethyl) acrylate is particularly preferable in that the effect of improving heat resistance is high. As for the monomer represented by the general formula (101), only one type may be used, or two or more types may be used in combination.

  The content ratio of the monomer represented by the general formula (101) in the monomer component used in the polymerization step has a lower limit value in a preferable range in terms of heat resistance, solvent resistance, and surface hardness, and was obtained. There is an upper limit of a preferable range from the viewpoint of molding processability of the polymer, and based on these viewpoints, it is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, still more preferably 10 to 60% by mass, and particularly preferably. Is 10-50 mass%.

The monomer component used in the polymerization step may contain a monomer other than the monomer represented by the general formula (101). Such monomers are not particularly limited, but preferred examples include acrylic acid esters, hydroxyl group-containing monomers, unsaturated carboxylic acids, and monomers represented by the following general formula (102). Only one type of monomer other than the monomer represented by formula (101) may be used, or two or more types may be used in combination.
Formula (102):

(Wherein R ⁴ represents a hydrogen atom or a methyl group, X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an —OAc group, a —CN group, a —CO—R ⁵ group, or —CO It represents ^{-O-R 6} group, Ac represents an acetyl group, ^{R 5} and ^{R 6} represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms.)

  The weight average molecular weight of the lactone ring-containing polymer is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,000,000, and particularly preferably 50,000 to 500,000.

  The lactone ring-containing polymer has a mass reduction rate within a range of 150 to 300 ° C. in dynamic TG measurement, preferably 1% or less, more preferably 0.5% or less, and still more preferably 0.3% or less. It is good. As a method for measuring dynamic TG, the method described in JP-A-2002-138106 can be used.

  Since the lactone ring-containing polymer has a high cyclization condensation reaction rate, there is little dealcoholization reaction in the production process of the molded product, and bubbles and silver stripes (silver streaks) are formed in the molded product after molding due to the alcohol. The disadvantage of entering can be avoided. Furthermore, since the lactone ring structure is sufficiently introduced into the polymer due to a high cyclization condensation reaction rate, the obtained lactone ring-containing polymer has high heat resistance.

  The lactone ring-containing polymer has a coloring degree (YI) of preferably 6 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1 or less when a chloroform solution having a concentration of 15% by mass is used. . If the degree of coloring (YI) is 6 or less, problems such as loss of transparency due to coloring are unlikely to occur, and therefore, it can be preferably used in the present invention.

  The lactone ring-containing polymer has a 5% mass reduction temperature in thermal mass spectrometry (TG) of preferably 330 ° C. or higher, more preferably 350 ° C. or higher, and still more preferably 360 ° C. or higher. The 5% mass reduction temperature in thermal mass spectrometry (TG) is an indicator of thermal stability, and by setting it to 330 ° C. or higher, sufficient thermal stability tends to be exhibited. The thermal mass spectrometry can use the apparatus for measuring the dynamic TG.

  The glass transition temperature (Tg) of the lactone ring-containing polymer is preferably 115 ° C to 180 ° C, more preferably 120 ° C to 170 ° C, and still more preferably 125 ° C to 160 ° C.

(2) Maleic anhydride polymer having a succinic anhydride ring in the main chain
By forming a succinic anhydride structure in the main chain in the molecular chain of the polymer (in the main skeleton of the polymer), the acrylic resin as a copolymer is given high heat resistance, and the glass transition temperature ( Tg) is also preferable because it increases.
The glass transition temperature (Tg) of the maleic anhydride polymer having a succinic anhydride ring in the main chain is preferably 110 ° C to 160 ° C, more preferably 115 ° C to 160 ° C, still more preferably 120 ° C to 160 ° C. is there.
The weight average molecular weight of the maleic anhydride polymer having a succinic anhydride ring in the main chain is preferably in the range of 50,000 to 500,000.

The maleic anhydride unit used for copolymerization with the acrylic resin is not particularly limited, but JP-A-2008-216586, JP-A-2009-052021, JP-A-2009-196151, JP-T-2012-504783. Mention may be made of maleic acid-modified resins described in the respective publications.
In addition, these do not limit this invention.
As a commercially available maleic acid-modified resin, Delpet 980N manufactured by Asahi Kasei Chemicals Corporation, which is a maleic acid-modified MAS resin (methyl methacrylate-acrylonitrile-styrene copolymer), can be preferably used.
In addition, a method for producing an acrylic resin containing a maleic anhydride unit is not particularly limited, and a known method can be used.

  The maleic acid-modified resin is not limited as long as the resulting polymer contains maleic anhydride units, and examples thereof include (anhydrous) maleic acid-modified MS resin, (anhydrous) maleic acid-modified MAS resin (methacrylic acid). Methyl-acrylonitrile-styrene copolymer), (anhydrous) maleic acid modified MBS resin, (anhydrous) maleic acid modified AS resin, (anhydrous) maleic acid modified AA resin, (anhydrous) maleic acid modified ABS resin, ethylene-maleic anhydride Examples thereof include acid copolymers, ethylene-acrylic acid-maleic anhydride copolymers, and maleic anhydride grafted polypropylene.

The maleic anhydride unit has a structure represented by the following general formula (200).
General formula (200):

In the general formula (200), R ²¹ and R ²² each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms.
The organic residue is not particularly limited as long as it has 1 to 20 carbon atoms, and examples thereof include a linear or branched alkyl group, a linear or branched alkylene group, an aryl group, and an -OAc group. , -CN group and the like. The organic residue may contain an oxygen atom. Ac represents an acetyl group.
R ²¹ and R ²² preferably have 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms.

In the case where R ²¹ and R ²² each represent a hydrogen atom, it is preferable that other copolymer components are further included from the viewpoint of adjusting the intrinsic birefringence. As such a ternary or higher heat-resistant acrylic resin, for example, methyl methacrylate-maleic anhydride-styrene copolymer can be preferably used.

(3) Polymer having glutaric anhydride ring structure in the main chain The polymer having glutaric anhydride ring structure in the main chain is a polymer having a glutaric anhydride unit.

  The polymer having a glutaric anhydride unit preferably has a glutaric anhydride unit represented by the following general formula (300) (hereinafter referred to as a glutaric anhydride unit).

  General formula (300):

In general formula (300), R <^31> , R ^<32 > represents a hydrogen atom or a C1-C20 organic residue each independently. The organic residue may contain an oxygen atom. R ³¹ and R ³² particularly preferably represent the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms.

The polymer having glutaric anhydride units is preferably an acrylic resin containing glutaric anhydride units. The acrylic resin preferably has a glass transition temperature (Tg) of 120 ° C. or higher from the viewpoint of heat resistance.
The glass transition temperature (Tg) of the polymer having a glutaric anhydride ring structure in the main chain is preferably 110 ° C to 160 ° C, more preferably 115 ° C to 160 ° C, and further preferably 120 ° C to 160 ° C.
The weight average molecular weight of the polymer having a glutaric anhydride ring structure in the main chain is preferably in the range of 50,000 to 500,000.

  As content of the glutaric anhydride unit with respect to acrylic resin, 5-50 mass% is preferable, More preferably, it is 10-45 mass%. When the content is 5% by mass or more, more preferably 10% by mass or more, an effect of improving heat resistance can be obtained, and further an effect of improving weather resistance can be obtained.

(4) Acrylic resin having a glutarimide ring structure in the main chain An acrylic resin having a glutarimide ring structure in the main chain (hereinafter also referred to as a glutarimide resin) is optical by having a glutarimide ring structure in the main chain. A desirable balance of properties can be expressed in terms of properties and heat resistance. The acrylic resin having a glutarimide ring structure in the main chain is at least a glutarimide unit represented by the following general formula (400) (wherein R ³⁰¹ , R ³⁰² and R ³⁰³ are independently hydrogen or carbon number) 1 to 12 unsubstituted or substituted alkyl groups, cycloalkyl groups, and aryl groups.) It is preferable to contain a glutarimide resin having 20% by mass or more.

Formula (400):

As preferred glutarimide units constituting the glutarimide resin used in the present invention, R ³⁰¹ and R ³⁰² are a hydrogen atom or a methyl group, and R ³⁰³ is a methyl group or a cyclohexyl group. The glutarimide unit may be a single type or may include a plurality of types in which R ³⁰¹ , R ³⁰² , and R ³⁰³ are different.

  A preferred second structural unit constituting the glutarimide resin used in the present invention is a unit composed of an acrylate ester or a methacrylate ester. Preferable acrylic acid ester or methacrylic acid ester structural unit includes methyl acrylate, ethyl acrylate, methyl methacrylate, methyl methacrylate and the like. Another preferred imidizable unit includes N-alkyl methacrylamide such as N-methyl methacrylamide and N-ethyl methacrylamide. These second structural units may be of a single type or may include a plurality of types.

  The content of the glutarimide unit represented by the general formula (400) in the glutarimide resin is preferably 20% by mass or more and 95% by mass or less based on the total repeating unit of the glutarimide resin. More preferably, it is 50-90 mass%, More preferably, it is 60-80 mass%. When the content of the glutarimide unit is 20% by mass or more, it is preferable from the viewpoint of ensuring heat resistance and transparency of the obtained film. If it is 95 mass% or less, it is preferable from a viewpoint of the brittleness of a film, transparency, and film formation.

  The glutarimide resin may be further copolymerized with a third structural unit, if necessary. Preferred examples of the third structural unit include styrene monomers such as styrene, substituted styrene and α-methylstyrene, acrylic monomers such as butyl acrylate, and nitrile monomers such as acrylonitrile and methacrylonitrile. , A structural unit obtained by copolymerizing maleimide monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide can be used. These may be directly copolymerized with the glutarimide unit and the imidizable unit in the glutarimide resin, and graft copolymerized with the resin having the glutarimide unit and the imidizable unit. It may be polymerized. When the third component is added, the content in the glutarimide resin is preferably 5 mol% or more and 30 mol% or less based on the total repeating units in the glutarimide resin.

  The glutarimide resin is described in US Pat. No. 3,284,425, US Pat. No. 4,246,374, JP-A-2-153904, and the like, and is obtained by using methyl methacrylate as a main raw material as a resin having an imidizable unit. It can be obtained by using a resin and imidizing the resin having an imidizable unit with ammonia or a substituted amine. When obtaining a glutarimide resin, a unit composed of acrylic acid, methacrylic acid, or an anhydride thereof may be introduced into the glutarimide resin as a reaction by-product. The presence of such a structural unit, particularly an acid anhydride, is not preferable because it reduces the total light transmittance and haze of the obtained film of the present invention. The acrylic acid or methacrylic acid content is 0.5 milliequivalent or less per gram of resin, preferably 0.3 milliequivalent or less, more preferably 0.1 milliequivalent or less. In addition, as seen in JP-A No. 02-153904, it is also possible to obtain a glutarimide resin by imidization using a resin mainly composed of N-methylacrylamide and methacrylic acid methyl ester.

The glass transition temperature (Tg) of the glutar resin is preferably 110 ° C. to 160 ° C., more preferably 115 ° C. to 160 ° C., and still more preferably 120 ° C. to 160 ° C.
The weight average molecular weight of the glutar resin is preferably in the range of 50,000 to 500,000.

  The optical film of the present invention may be mixed with other resins in addition to the acrylic resin. The mass ratio of the acrylic resin and the other resin is preferably 70:30 to 100: 0, more preferably 80:20 to 100: 0, and still more preferably 90:10 to 100: 0. Particularly preferred is 98: 2 to 100: 0, and most preferred is 100: 0. It is preferable for the mass ratio of the acrylic resin and the other resin to be in the range of 80:20 to 100: 0 because the moisture permeability is low and the humidity expansion of the polarizer due to water transmitted through the film can be further suppressed.

-Manufacturing method of optical film made of acrylic resin-
Hereinafter, a production method for forming a thermoplastic resin film made of an acrylic resin will be described in detail.
In order to form an optical film using an acrylic resin as a main component, for example, a film raw material is pre-blended with a conventionally known mixer such as an omni mixer, and then the obtained mixture is extruded and kneaded. In this case, the mixer used for extrusion kneading is not particularly limited. For example, a conventionally known mixer such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader can be used. .

  Examples of the film forming method include conventionally known film forming methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Of these film forming methods, the melt extrusion method is particularly suitable.

  Examples of the melt extrusion method include a T-die method and an inflation method, and the molding temperature at that time may be appropriately adjusted according to the glass transition temperature of the film raw material, and is not particularly limited. For example, it is preferably 150 ° C to 350 ° C, more preferably 200 ° C to 300 ° C.

  When forming a film by the T-die method, a roll-shaped film can be obtained by attaching a T-die to the tip of a known single-screw extruder or twin-screw extruder and winding the film extruded into a film. it can. At this time, it is possible to perform uniaxial stretching by appropriately adjusting the temperature of the take-up roll and adding stretching in the extrusion direction. Further, simultaneous biaxial stretching, sequential biaxial stretching, and the like can be performed by stretching the film in a direction perpendicular to the extrusion direction.

The optical film of the present invention is preferably a stretched film made of an acrylic resin. In the case of a stretched film, either a uniaxially stretched film or a biaxially stretched film may be used. In the case of a biaxially stretched film, either a simultaneous biaxially stretched film or a sequential biaxially stretched film may be used. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved.
The thickness of the optical film made of acrylic resin is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm. When the thickness is 5 μm or more, it is preferable because improvement in film strength and durability (crimping) can be suppressed. By setting the thickness to 80 μm or less, it is preferable because transparency of the film and appropriate moisture permeability can be ensured.

The optical film of the present invention satisfies the relationship of the formula (1) in the tensile modulus in the machine direction (MD direction) and the tensile modulus in the direction perpendicular to the machine direction (TD direction).
Formula (1) Tensile modulus in MD direction / Tension modulus in TD direction> 1.36
More preferably,
1.36 <tensile modulus in MD direction / tensile modulus in TD direction <1.80
Range.
When an acrylic film having a ratio of tensile modulus in the machine direction (MD direction) / tensile modulus in the direction perpendicular to the machine direction (TD direction) is greater than 1.36, a conventional acrylic film (of tensile modulus) Compared with the case where the ratio is about 1.08 at the maximum, the display unevenness of the liquid crystal display device caused by the warpage of the liquid crystal cell can be clearly reduced.
The display unevenness that occurs in the liquid crystal display device refers to a planar failure that occurs as a result of the liquid crystal cell being warped and the four corners of the liquid crystal cell come into contact with the bezel. The liquid crystal cell of the liquid crystal display device has two polarizing plates on both sides. For example, when the liquid crystal display device is placed in a high humidity environment, both the front and rear polarizing plates contain water and swell. Thereafter, when the liquid crystal display device is taken out from the high humidity environment, the hydrated and swollen polarizing plate dries and shrinks. Here, the rear-side polarizing plate is disposed in the liquid crystal display device, and the front-side polarizing plate is faster because it is placed in an environment that is more airtight than the front-side polarizing plate. Since it dries, a larger shrinkage force is generated, whereas the rear polarizing plate is slower to dry and the shrinkage force is less generated. Therefore, for the purpose of effectively reducing display unevenness, it is preferable that an optical film satisfying the relationship of the formula (1) is used for the front side polarizing plate, which is used for the front side polarizing plate and the rear side polarizing plate. Of the four optical films that are used, two of the films far from the liquid crystal cell are more preferably optical films that satisfy the relationship of formula (1), and are used for the front-side polarizing plate and the rear-side polarizing plate. It is more preferable that all four optical films are optical films satisfying the relationship of the formula (1).
When the optical film of the present invention is used for a front-side polarizing plate, it is arranged so that the machine direction (MD direction) is the long-side direction (usually the left-right direction) of the display surface of the liquid crystal display device. In the case of being used for the rear polarizing plate, it is preferably arranged so that the machine direction (MD direction) is the direction of the short side (usually the vertical direction) of the display surface of the liquid crystal display device.

  In recent years, liquid crystal display devices have been increased in size and thickness, and their applications have been diversified, and the demand for durability has become stricter. For example, as the liquid crystal display device becomes thinner, it has become a problem that light unevenness of a circular shape or an elliptic shape occurs on the display surface, and this improvement is demanded. As a cause of the occurrence of this light unevenness, it can be mentioned that contact between the backlight member and the backlight side polarizing plate of the liquid crystal panel member is likely to occur due to thinning. When the liquid crystal display device is used for a long period of time in a state where the backlight member and the backlight side polarizing plate are in contact with each other, or when used in a hot and humid environment, moisture easily collects at the contact portion, and the moisture is polarized. As a result of the penetration of the liquid crystal, the amount of expansion and contraction of the polarizing plate at the contact part and non-contact part of the backlight member and the backlight side polarizing plate changes, resulting in a phase difference due to photoelasticity and light unevenness. It is done. Since an optical film made of an acrylic resin has a photoelastic coefficient of about 0 Br, a phase difference caused by photoelasticity does not appear. Therefore, the light unevenness can be greatly reduced by using an optical film made of acrylic resin on the liquid crystal cell side of the rear side polarizing plate.

The tensile elastic modulus in the machine direction (MD direction) of the optical film of the present invention is more preferably 1.7 × 10 ^{9 to} 5.5 × 10 ⁹ N / m ² , and 2.0 × 10 ^{9 to} 5. 5 × 10 ⁹ N / m ² is more preferable, and 2.5 × 10 ^{9 to} 5.5 × 10 ⁹ N / m ² is particularly preferable. The tensile elastic modulus in the direction perpendicular to the machine direction (TD direction) of the optical film of the present invention is more preferably 1.2 × 10 ^{9 to} 4.0 × 10 ⁹ N / m ² , and preferably 1.2 × 10 9. more preferably ^{9 ~3.5 × 10 9 N / m} 2, and particularly preferably ^{1.2 × 10 9 ~3.2 × 10 9} N / m 2.

  Generally, the higher the tensile elastic modulus, the harder it is to scratch when the polarizing plate surface is scratched. That is, it is preferable that the tensile modulus MD / TD ratio is large (MD tensile modulus is high) because scratch resistance in the MD direction can be improved. For example, it is hard to be damaged at the time of roll conveyance at the time of polarizing plate production, and the yield at the time of roll conveyance can be improved.

  In the optical film of the present invention, the retardation value Re in the film plane represented by Re = (nx−ny) × d is preferably 0 nm ≦ Re <20 nm. More preferably, 0 nm ≦ Re ≦ 15 nm, and further preferably 0 nm ≦ Re ≦ 10 nm.

  In the optical film of the present invention, the retardation value Rth in the film thickness direction represented by Rth = ((nx + ny) / 2−nz) × d is preferably | Rth | ≦ 25 nm. In the optical film of the present invention, the retardation value Rth in the film thickness direction represented by Rth = ((nx + ny) / 2−nz) × d is preferably | Rth | ≦ 25 nm. More preferably, | Rth | ≦ 20 nm, more preferably | Rth | ≦ 10 nm, and most preferably −10 nm ≦ Rth ≦ 5 nm.

In this specification, Re (λnm) and Rth (λnm) each represent in-plane retardation and retardation in the thickness direction at a wavelength λ (unit: nm). Re (λnm) is measured by making light having a wavelength of λnm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments). In selecting the measurement wavelength λnm, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like. When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λnm) is calculated by the following method.
Rth (λnm) is Re (λnm), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) (if there is no slow axis, any in-plane film The light is incident at a wavelength of λ nm in 10 ° steps from the normal direction to 50 ° on one side with respect to the normal direction of the film (with the direction of the rotation axis as the rotation axis), and a total of 6 points are measured. KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.
In the above, there is no description regarding λ, and when only Re and Rth are described, it represents a value measured using light having a wavelength of 550 nm. In addition, in the case of a film having a retardation value of zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, the retardation value at a tilt angle larger than that tilt angle. After changing its sign to negative, KOBRA 21ADH or WR calculates.
In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (when there is no slow axis, the arbitrary direction in the film plane is the rotation axis), Rth can also be calculated from the following formulas (3) and (4) based on the value, the assumed value of the average refractive index, and the input film thickness value.

Formula (3)

[In the formula, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. Further, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, nz represents the refractive index in the thickness direction orthogonal to nx and ny, and d Represents the film thickness of the film. ]
Formula (4): Rth = ((nx + ny) / 2−nz) × d
In the above measurement, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. If the average refractive index is not known, it can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59).

<Polarizing plate>
The polarizing plate of the present invention has the polarizer and the optical film of the present invention on at least one surface of the polarizer. The polarizing plate of the present invention preferably has the optical film of the present invention on both surfaces of a polarizer.
The polarizing plate of the present invention preferably has the polarizer and the optical film of the present invention as a protective film for the polarizer, and the polarizing plate has a protective film / polarizer / protective film or protective film / polarized light A child and a protective film / polarizer / coating layer are preferred.
Regarding the polarizing plate protective film which comprises the polarizing plate of this invention, there is no restriction | limiting in particular about the material which can be used for protective films other than the optical film of the said invention. It may be a layer or film made of various polymers (hereinafter sometimes referred to collectively as “film”). For example, cellulose acylate polymer, polycarbonate polymer, polyester such as polyethylene terephthalate and polyethylene naphthalate Polymers, acrylic polymers such as polymethyl methacrylate, styrene polymers such as polystyrene and acrylonitrile / styrene copolymer (AS resin), and the like can be used. In addition, polyolefins such as polyethylene and polypropylene, polyolefin polymers such as ethylene / propylene copolymers, cycloolefin polymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinylidene chloride polymer, vinyl alcohol polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the aforementioned polymer A polymer layer or a film may be produced by selecting one type or two or more types of polymers from a polymer or the like mixed with a polymer as a main component. Further, it may be a layer formed by polymerizing a rod-like liquid crystal having a polymerizable group or a discotic liquid crystal in a predetermined alignment state and fixing it.
In the polarizing plate of the present invention, when another optical film is bonded to the surface of the polarizer opposite to the surface on which the optical film of the present invention is bonded, the other optical film may have a functional layer. it can. In order to improve adhesion with a polarizer or other functional layer, an easy adhesion layer can be provided as the functional layer.

The polarizing plate of the present invention can be produced by a general method. For example, it is a method of laminating a polarizer and the optical film of the present invention.
For the lamination, an adhesive is usually used. The adhesive layer between the polarizer and the polarizing plate protective film on both sides can have a thickness of about 0.01 to 30 μm, preferably 0.01 to 10 μm, more preferably 0.05 to 5 μm. is there. If the thickness of the adhesive layer is within this range, no adhesion or practical problem will be obtained without floating or peeling between the laminated polarizing plate protective film and the polarizer.

As one of the preferable adhesives, an aqueous adhesive, that is, an adhesive component dissolved or dispersed in water can be exemplified, and an adhesive made of an aqueous polyvinyl alcohol resin solution is preferably used.
In an adhesive comprising an aqueous polyvinyl alcohol resin solution, the polyvinyl alcohol resin includes a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as vinyl acetate and this. Examples include vinyl alcohol copolymers obtained by saponifying a copolymer with other polymerizable monomers, and modified polyvinyl alcohol polymers obtained by partially modifying their hydroxyl groups.
To this adhesive, a polyvalent aldehyde, a water-soluble epoxy compound, a melamine compound, a zirconia compound, a zinc compound, a glyoxylate and the like may be added as a crosslinking agent. When an aqueous adhesive is used, the thickness of the adhesive layer obtained therefrom is usually 1 μm or less.

Another preferred adhesive is a curable adhesive composition containing an epoxy compound that is cured by irradiation with active energy rays or heating. Here, the curable epoxy compound has at least two epoxy groups in the molecule. In this case, the adhesive between the polarizer and the protective film is applied to the coating layer of the adhesive composition by irradiating active energy rays or applying heat, and a curable epoxy compound contained in the adhesive. It can carry out by the method of hardening. Curing of the epoxy compound is generally performed by cationic polymerization of the epoxy compound. Further, from the viewpoint of productivity, this curing is preferably performed by irradiation with active energy rays.
When a curable adhesive is used, the thickness of the adhesive layer obtained therefrom is usually about 0.5 to 5 μm.

  When using a curable adhesive, after bonding a film using a bonding roll, drying is performed as necessary, and the curable adhesive is cured by irradiating with active energy rays or heating. . The light source of the active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable, and specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp A microwave excited mercury lamp, a metal halide lamp, or the like is preferably used.

  From the viewpoint of weather resistance, refractive index, cationic polymerizability, etc., the epoxy compound contained in the curable adhesive composition is preferably one that does not contain an aromatic ring in the molecule. Examples of epoxy compounds that do not contain an aromatic ring in the molecule include hydrogenated epoxy compounds, alicyclic epoxy compounds, and aliphatic epoxy compounds. Epoxy compounds suitably used for such a curable adhesive composition are described in detail in, for example, Japanese Patent Application Laid-Open No. 2004-245925.

  In addition, when the optical film of the present invention and the polarizer are bonded with an adhesive, the surface of the optical film of the present invention facing the polarizer is treated with a surface treatment (eg, glow) for the purpose of improving the adhesive strength. Discharge treatment, corona discharge treatment, ultraviolet (UV) treatment) or easy adhesion layer formation may be performed. The materials and forming methods of the easy adhesion layer described in JP 2007-127893 A, JP 2007-127893 A, and the like can be used.

  Moreover, when using films other than the optical film of this invention as a protective film, for example in the aspect using a cellulose acylate film (cellulose acylate type polymer layer), the back surface of a cellulose acylate film and a polarizer are bonded together. Can be produced. In an embodiment in which an aqueous adhesive is used for bonding the cellulose acylate film and the polarizer, it is preferable that the bonding surface of the cellulose acylate film is subjected to alkali saponification treatment. Moreover, complete saponification type polyvinyl alcohol aqueous solution can be used for bonding.

  As said polarizer, what was manufactured by the conventionally well-known method can be used, and a polyvinyl-alcohol-type polarizer is preferable. For example, a film made of a hydrophilic polymer such as polyvinyl alcohol or ethylene-modified polyvinyl alcohol having an ethylene unit content of 1 to 4 mol%, a polymerization degree of 2000 to 4000, and a saponification degree of 99.0 to 99.99 mol%, A film stretched by treatment with a dichroic dye such as the above, or a film oriented by treating a plastic film such as vinyl chloride is used.

  Moreover, as a method of obtaining a polarizer film of 10 μm or less by stretching and dyeing in the state of a laminated film in which a polyvinyl alcohol layer is formed on a substrate, Patent No. 5048120, Patent No. 5143918, Patent No. 5048120 No. 4, Patent No. 4691205, Patent No. 4751481 and Patent No. 4751486 can be cited, and known techniques relating to these polarizers can also be preferably used for the polarizing plate of the present invention.

<Functional layer>
A functional layer may be provided on at least one surface of the optical film of the present invention. Examples of the functional layer include a three-dimensional image display pattern retardation layer, a λ / 4 layer, an optically anisotropic layer, a hard coat layer, an antireflection layer, an antiglare layer, an antistatic layer, and an easy adhesion layer. Each functional layer may be used alone or in combination. In particular, in the embodiment in which the pattern retardation layer or the λ / 4 layer is provided on the optical film of the present invention, the other surface of the optical film of the present invention, or the pattern retardation layer or the λ / 4 layer is provided. An embodiment in which a hard coat layer is provided is preferred. Further, in the aspect in which the hard coat layer is provided on the pattern retardation layer or the λ / 4 layer, the layer disposed on the viewer side of the pattern retardation layer or the λ / 4 layer, or the hard coat layer absorbs ultraviolet rays. It is preferable to have a function.
When the polarizing plate of the present invention has a structure in which a polarizer is sandwiched between the protective film / polarizer / functional layer, that is, the protective film, the optical film of the present invention and the functional layer, in the liquid crystal display device, the functional layer is In an embodiment in which the functional layer is disposed closer to the liquid crystal cell, the functional layer is preferably a λ / 4 layer, an optically anisotropic layer, a hard coat layer, an antistatic layer, or an easy adhesion layer.

<Pattern retardation layer>
The pattern retardation layer includes a first retardation region and a second retardation region in which at least one of an in-plane slow axis direction and an in-plane retardation is different from each other, and the first and second retardation regions are in-plane The first phase difference region and the second phase difference region have a boundary portion. An example is an optically anisotropic layer in which the first and second retardation regions each have Re of about λ / 4 and the in-plane slow axes are orthogonal to each other. There are various methods for forming such a pattern retardation layer, and it is formed by polymerizing and fixing a rod-like liquid crystal having a polymerizable group in a horizontally aligned state and a discotic liquid crystal in a vertically aligned state. It is preferable to do.
In general, liquid crystal compounds can be classified into a rod type and a disk type from the shape. In addition, there are low and high molecular types, respectively. Polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992). Any liquid crystal compound can be used in the patterned optically anisotropic layer used in the present invention, but a rod-like liquid crystal compound or a disk-like liquid crystal compound is preferably used. Two or more kinds of rod-like liquid crystal compounds, two or more kinds of disk-like liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a disk-like liquid crystal compound may be used. It is more preferable to use a rod-like liquid crystal compound or a disk-like liquid crystal compound having a reactive group, since at least one of the reactive groups in one liquid crystal molecule is at least one because a change in temperature and humidity can be reduced. Is more preferable. The liquid crystal compound may be a mixture of two or more types, and in that case, at least one preferably has two or more reactive groups.
As the rod-like liquid crystal compound, for example, those described in JP-A-11-513019 and JP-A-2007-279688 can be preferably used, and examples of the discotic liquid crystal compound include JP-A-2007-108732. Although what is described in gazette and Unexamined-Japanese-Patent No. 2010-244038 can be used preferably, it is not limited to these.

  It is also preferable that the liquid crystal compound has two or more reactive groups having different polymerization conditions. In this case, it is possible to produce a retardation layer containing a polymer having an unreacted reactive group by selecting conditions and polymerizing only a part of plural types of reactive groups. The polymerization conditions used may be the wavelength range of ionizing radiation used for polymerization immobilization, or the difference in polymerization mechanism used, but preferably a radical reaction group and a cationic reaction that can be controlled by the type of initiator used. A combination of groups is good. A combination in which the radical reactive group is an acrylic group and / or a methacryl group and the cationic group is a vinyl ether group, an oxetane group and / or an epoxy group is particularly preferable because the reactivity can be easily controlled.

The optically anisotropic layer can be formed by various methods using an alignment film, and the production method is not particularly limited.
The first aspect uses a plurality of actions that affect the alignment control of the liquid crystal, and then eliminates any action by an external stimulus (such as heat treatment) to make the predetermined alignment control action dominant. It is. For example, by combining the alignment control ability of the alignment film with the alignment control ability of the alignment control agent added to the liquid crystal compound, the liquid crystal is brought into a predetermined alignment state and fixed to form one retardation region. After that, by external stimulus (heat treatment, etc.), one of the actions (for example, the action by the alignment control agent) disappears, and the other orientation control action (the action by the alignment film) becomes dominant, thereby causing another alignment state. Is fixed and the other phase difference region is formed. For example, a predetermined pyridinium compound or imidazolium compound is unevenly distributed on the surface of the hydrophilic polyvinyl alcohol alignment film because the pyridinium group or imidazolium group is hydrophilic. In particular, if the pyridinium group is further substituted with an amino group that is a substituent of an acceptor of a hydrogen atom, intermolecular hydrogen bonds are generated with polyvinyl alcohol, and are unevenly distributed on the surface of the alignment film at a higher density. At the same time, due to the effect of hydrogen bonding, the pyridinium derivative is aligned in the direction orthogonal to the main chain of polyvinyl alcohol, so that the orthogonal alignment of the liquid crystal is promoted with respect to the rubbing direction. Since the pyridinium derivative has a plurality of aromatic rings in the molecule, a strong intermolecular π-π interaction occurs between the liquid crystal, particularly the discotic liquid crystal compound described above, and the orientation of the discotic liquid crystal. Induces orthogonal orientation in the vicinity of the film interface. In particular, when a hydrophobic aromatic ring is connected to a hydrophilic pyridinium group, it also has an effect of inducing vertical alignment due to the hydrophobic effect. However, the effect is that when heated above a certain temperature, the hydrogen bond is broken, the density of the pyridinium compound or the like on the surface of the alignment film is lowered, and the action disappears. As a result, the liquid crystal is aligned by the regulating force of the rubbing alignment film itself, and the liquid crystal is in a parallel alignment state. Details of this method are described in JP 2012-8170 A, the contents of which are incorporated herein by reference.

  In the second aspect, a pattern alignment film is used. In this embodiment, pattern alignment films having different alignment control capabilities are formed, and a liquid crystal compound is disposed thereon to align the liquid crystal. The alignment of the liquid crystal is regulated by the respective alignment control ability of the pattern alignment film, thereby achieving different alignment states. By fixing the respective alignment states, the patterns of the first and second retardation regions are formed according to the alignment film pattern. The pattern alignment film can be formed using a printing method, mask rubbing for the rubbing alignment film, mask exposure for the photo alignment film, or the like. Alternatively, the alignment film can be formed uniformly, and an additive that affects the alignment control ability (for example, the onium salt or the like) can be separately printed in a predetermined pattern to form the pattern alignment film. A method using a printing method is preferable in that large-scale equipment is not required and manufacturing is easy. Details of this method are described in JP 2012-032661 A, the contents of which are incorporated herein by reference.

  Moreover, you may use the 1st and 2nd aspect together. An example is an example in which a photoacid generator is added to the alignment film. In this example, a photoacid generator is added to the alignment film, and pattern exposure exposes a region where the photoacid generator is decomposed to generate an acidic compound and a region where no acid compound is generated. The photoacid generator remains almost undecomposed in the unirradiated portion, and the interaction between the alignment film material, the liquid crystal, and the alignment control agent added as required dominates the alignment state, and the liquid crystal has its slow axis. Is oriented in a direction perpendicular to the rubbing direction. When the alignment film is irradiated with light and an acidic compound is generated, the interaction is no longer dominant, the rubbing direction of the rubbing alignment film dominates the alignment state, and the liquid crystal has its slow axis parallel to the rubbing direction. Parallel orientation. As the photoacid generator used for the alignment film, a water-soluble compound is preferably used. Examples of photoacid generators that can be used include Prog. Polym. Sci. , 23, 1485 (1998). As the photoacid generator, pyridinium salts, iodonium salts and sulfonium salts are particularly preferably used. Details of this method are described in JP 2012-150428 A, the contents of which are incorporated herein by reference.

(Shape of the first area and the second area)
The optical film of the present invention has a first retardation region (hereinafter also simply referred to as a first region) and a second retardation region (hereinafter also simply referred to as a second region) having different birefringence, and the first An optically anisotropic layer (hereinafter also referred to as a pattern phase difference) in which one phase difference region and the second phase difference region are alternately patterned for each line is included. From the viewpoint of use for a 3D stereoscopic image display system, it is preferable that the first region and the second region have a strip shape in which the lengths of the short sides of the first region and the second region are approximately the same.

In the optical film of the present invention, when the slow axis of the first region and the slow axis of the second region are substantially orthogonal, the first region and the second region are passed when 3D video display is performed. This is preferable from the viewpoint of changing the polarization state of light from linearly polarized light to circularly polarized light, or from circularly polarized light to linearly polarized light.
In the optical film of the present invention, the slow axis of the first region and the slow axis of the second region are orthogonal to each other when passing through the first region and the second region when displaying a 3D image. It is more preferable from the viewpoint that the polarization state of the obtained light can be changed from linearly polarized light to circularly polarized light, or from circularly polarized light to linearly polarized light without being elliptically polarized light.

  In the optical film of the present invention, the direction of the long side of the pattern and the direction in which the sound speed of the support is maximized are substantially orthogonal from the viewpoint of reducing the shift between the pattern area and the pixel and suppressing crosstalk. preferable.

(Retardation)
As described above, the pattern retardation layer having a function of converting from linearly polarized light to circularly polarized light or from circularly polarized light to linearly polarized light preferably has a retardation of ¼ of the wavelength. In general, it is called a quarter-wave plate, and Re = 137.5 nm is an ideal value at a visible light wavelength of 550 nm.
Further, the pattern retardation layer for converting linearly polarized light into circularly polarized light or circularly polarized light into linearly polarized light is not limited to having a retardation of ¼ wavelength. For example, a retardation of -1/4 or 3/4 of the wavelength may be used, and the retardation may be ¼ ± n / 2 (n is an integer) of the wavelength when expressed by a general formula.
Patterning in which the slow axis of the first region and the slow axis of the second region are orthogonal to each other may be performed by alternately forming regions having a retardation of -1/4 or 1/4 of the wavelength. At this time, the slow axes of each region are almost orthogonal. Further, the retardation of 1/4 and 3/4 of the wavelength may be patterned, and the slow axes of the mutual regions at this time are substantially parallel. However, the rotation directions of the circularly polarized light in the respective regions are reversed.
Further, in the patterning of the quarter of the wavelength and the retardation of the quarter, the retardation of 1/2 or −1/2 of the wavelength may be formed after the quarter of the wavelength is formed on the entire surface.
When the optical film of the present invention has a retardation of ¼ of the wavelength, the Re (550) value of the first region included in the optical film and the Re of the second region included in the optical film. (550) The value is preferably 30 to 250 nm, more preferably 50 to 230 nm, particularly preferably 100 to 200 nm, more preferably 105 to 180 nm, and more preferably 115 to 160 nm. Is more preferable, and it is more preferable that it is 120-150 nm.

  In addition, from the viewpoint of changing the polarization state of the light that has passed through the first region and the second region when displaying 3D images from linearly polarized light to circularly polarized light, or from circularly polarized light to linearly polarized light, the pattern retardation layer The total Re (550) of the support and the support is preferably 110 to 165 nm, more preferably 110 to 155 nm, and still more preferably 120 to 145 nm. In particular, the entire Re (550) of the pattern retardation layer and the support is in the above range, and the slow axes of the first region and the second region are substantially orthogonal to each other, so that the right-eye image and the left-eye can be accurately obtained. This is preferable from the viewpoint of changing the polarization state of the image for use.

<Λ / 4 layer>
The λ / 4 layer is an aspect of only the first retardation region described in the section of the pattern retardation layer. That is, it is not an aspect having two regions having different birefringence but an aspect having a uniform birefringence region. A preferable material and a range of retardation are the same as those of the pattern retardation layer.

<Optically anisotropic layer>
The optically anisotropic layer is a layer formed of the above-mentioned various polymers in a predetermined alignment state, or a layer formed by polymerizing a rod-like liquid crystal having a polymerizable group or a discotic liquid crystal in a predetermined alignment state and fixing it. That is. As the rod-like liquid crystal or discotic liquid crystal having a polymerizable group, the same material as that of the pattern retardation layer can be used.

<Hard coat layer>
The hard coat layer used in the present invention is a layer for imparting hardness and scratch resistance to the film. The said hard-coat layer can be formed by apply | coating a coating composition on the optical film of this invention which is a base film, and making it harden | cure, for example. Moreover, you may laminate | stack another functional layer on a hard-coat layer for the purpose of adding another function. Also, by adding fillers and additives to the hard coat layer, chemical performance such as mechanical, electrical and optical physical performance and water / oil repellency can be imparted to the hard coat layer itself. .
The hard coat layer preferably has a thickness of 0.1 to 6 μm, more preferably 3 to 6 μm. By having a thin hard coat layer in the above range, an optical film including a hard coat layer that has improved physical properties such as brittleness and curl suppression, reduced weight, and reduced manufacturing costs is obtained. Moreover, pencil hardness can be raised notably by making a base film into the MD direction and a large tensile elasticity modulus and it is more than the range of the said specific tensile elasticity modulus.

  The hard coat layer is preferably formed by curing the curable composition. The curable composition is preferably prepared as a liquid coating composition. An example of the said coating composition contains the monomer or oligomer for matrix formation binders, polymers, and an organic solvent. A hard coat layer can be formed by curing the coating composition after coating. For curing, a crosslinking reaction or a polymerization reaction can be used.

(Monomer or oligomer for matrix forming binder)
Examples of matrix forming binder monomers or oligomers that can be used include ionizing radiation curable polyfunctional monomers and polyfunctional oligomers. The polyfunctional monomer or polyfunctional oligomer is preferably a monomer capable of crosslinking reaction or polymerization reaction. The functional group of the ionizing radiation-curable polyfunctional monomer or polyfunctional oligomer is preferably a light, electron beam, or radiation polymerizable group, and among them, a photopolymerizable functional group is preferable.

  Examples of the photopolymerizable functional group include unsaturated polymerizable functional groups such as (meth) acryloyl group, vinyl group, styryl group, and allyl group, and ring-opening polymerizable functional groups such as epoxy compounds. Of these, a (meth) acryloyl group is preferred.

As a specific example of a photopolymerizable polyfunctional monomer having a photopolymerizable functional group,
(Meth) acrylic acid diesters of alkylene glycol such as neopentyl glycol acrylate, 1,6-hexanediol (meth) acrylate, propylene glycol di (meth) acrylate;
(Meth) acrylic acid diesters of polyoxyalkylene glycols such as triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate;
(Meth) acrylic acid diesters of polyhydric alcohols such as pentaerythritol di (meth) acrylate;
(Meth) acrylic acid diesters of ethylene oxide or propylene oxide adducts such as 2,2-bis {4- (acryloxy-diethoxy) phenyl} propane and 2,2-bis {4- (acryloxy-polypropoxy) phenyl} propane And the like.

  Furthermore, urethane (meth) acrylates, polyester (meth) acrylates, isocyanuric acid acrylates, and epoxy (meth) acrylates are also preferably used as the photopolymerizable polyfunctional monomer.

Among the above, esters of polyhydric alcohol and (meth) acrylic acid are preferable, and polyfunctional monomers having three or more (meth) acryloyl groups in one molecule are more preferable.
Specifically, (di) pentaerythritol tri (meth) acrylate, (di) pentaerythritol tetra (meth) acrylate, (di) pentaerythritol penta (meth) acrylate, (di) pentaerythritol hexa (meth) acrylate, tri Pentaerythritol triacrylate, tripentaerythritol hexatriacrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, EO-modified tri (meth) acrylate phosphate, 1,2,4-cyclohexanetetra (meth) acrylate, Printer glycerol triacrylate, 1,2,3-cyclohexane tetramethacrylate, polyester polyacrylate and caprolactone-modified tris (acryloyloxyethyl) isocyanurate, and the like.
In the present specification, “(meth) acrylate”, “(meth) acrylic acid”, and “(meth) acryloyl” represent “acrylate or methacrylate”, “acrylic acid or methacrylic acid”, and “acryloyl or methacryloyl”, respectively. .

Furthermore, resins having three or more (meth) acryloyl groups, such as relatively low molecular weight polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins And oligomers or prepolymers such as polyfunctional compounds such as polyhydric alcohols.
As specific compounds of polyfunctional acrylate compounds having three or more (meth) acryloyl groups, JP-A-2007-256844 [0096] and the like can be referred to.

As urethane acrylates, for example, alcohols, polyols, and / or hydroxyl group-containing compounds such as hydroxyl group-containing acrylates are reacted with isocyanates, and if necessary, polyurethane compounds obtained by these reactions (meth) Mention may be made of urethane acrylate compounds obtained by esterification with acrylic acid.
As specific examples of specific compounds, reference can be made to the description of [0017] in JP-A-2007-256844.

  Use of isocyanuric acid acrylates is preferable because curling can be further reduced. Examples thereof include isocyanuric acid diacrylates and isocyanuric acid triacrylates, and examples of specific compounds can be referred to JP-A-2007-256844 [0018] to [0021].

  In the hard coat layer, an epoxy compound can be further used to reduce shrinkage due to curing. As monomers having an epoxy group for constituting this, monomers having two or more epoxy groups in one molecule are used, and examples thereof include JP-A Nos. 2004-264563, 2004-264564, and Examples thereof include epoxy monomers described in 2005-37737, 2005-37738, 2005-140862, 2005-140862, 2005-140863, 2002-322430 and the like. It is also preferable to use a compound having both epoxy and acrylic functional groups such as glycidyl (meth) acrylate.

(Polymer compound)
The hard coat layer may contain a polymer compound. The explanation and preferred specific examples of the polymer compound are the same as those described in JP 2012-215812 A, and the contents described in this gazette are incorporated in the present specification.

(Curable composition)
Examples and preferred specific examples of the curable composition that can be used for forming the hard coat layer are the same as those described in JP 2012-215812 A, and the contents described in this gazette are described in this specification. Embedded in.

(Properties of hard coat layer)
The hard coat layer is preferably excellent in scratch resistance. Specifically, it is preferable to achieve 3H or higher when a pencil hardness test that is an index of scratch resistance is performed.

  The polarizing plate of the present invention may have other layers in addition to the optical film of the present invention and the hard coat layer in order to exhibit a function suitable for each application. For example, in addition to the antiglare layer and the clear hard coat layer, an antireflection layer, an antistatic layer, an antifouling layer, and the like may be included.

  In particular, since image display screens having various types of touch panels that have become popular in recent years are required to have fingerprint resistance and antifouling properties, an antifingerprint layer or antifouling layer is provided on the optical film of the present invention. It is also useful to form. Regarding the anti-fingerprint layer and the antifouling layer, for example, Japanese Patent No. 4517590, Japanese Patent No. 4638954, International Publication WO2010 / 090116, and International Publication WO2011 / 105594 can be referred to.

  The image display device is not limited, and may be a liquid crystal display device including a liquid crystal cell, an organic EL image display device including an organic EL layer, or a plasma image display device. A cellulose acylate polymer layer, a polyester polymer layer, an acrylic polymer layer, a cycloolefin polymer layer, and a layer made of a composition containing a liquid crystal compound have good bonding properties with a polarizer, and a polarizing plate. It is suitable for use in a liquid crystal display device as an essential member.

  At the time of producing the polarizing plate, when the optical film of the present invention has an in-plane slow axis, it is preferably bonded so that the in-plane slow axis and the transmission axis of the polarizer are parallel or orthogonal.

[Liquid Crystal Display]
The liquid crystal display device of the present invention has at least one polarizing plate of the present invention.
An example of the arrangement method of the optical film of the present invention in the polarizing plate is that the optical film of the present invention is disposed outside the polarizer without having a functional layer such as a hard coat layer (that is, the polarizer of the polarizing plate). It is a surface protective film of a polarizing plate arranged so as to be farther from the liquid crystal cell. Another example of the arrangement method of the optical film of the present invention is that the optical film of the present invention of the polarizing plate on the display surface side is disposed outside the polarizer in a state having a functional layer such as a hard coat layer (that is, the polarizing plate). This is a surface protective film of a polarizing plate disposed farther from the liquid crystal cell than the polarizer. In the liquid crystal display device of the present invention, it is also preferable that the polarizing plate is arranged so that the optical film of the present invention is closer to the liquid crystal cell than the other protective film.
As for other configurations, any configuration of a known liquid crystal display device can be adopted. There is no particular limitation on the mode, and TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroelectric Liquid Crystal), OCB (Optic STP). The liquid crystal display device can be configured in various display modes such as Nematic), VA (Vertically Aligned), and HAN (Hybrid Aligned Nematic).

As the liquid crystal display device of the present invention, a transmissive liquid crystal display device is preferable, and the transmissive liquid crystal display device is usually composed of a backlight, a liquid crystal cell, and two polarizing plates whose transmission axes are orthogonal to each other, The two polarizing plates are bonded to the viewing side and the backlight side of the liquid crystal cell via an adhesive layer.
The liquid crystal cell includes a liquid crystal layer and two glass substrates provided on both sides of the liquid crystal layer.
As the glass substrate for the liquid crystal display device, silicate glass is used, preferably silica glass or borosilicate glass is used, and most preferably non-alkali borosilicate glass is used. If an alkali component is contained in a glass substrate for a liquid crystal display device, the alkali component is eluted and the TFT may be damaged. Here, the alkali-free borosilicate glass is a glass that does not substantially contain an alkali component, and specifically, a glass having an alkali component of 1000 ppm or less. The content of the alkali component in the present invention is preferably 500 ppm or less, more preferably 300 ppm or less of the alkali component.

  The glass substrate for a liquid crystal display device is a plate-like body having a substantially rectangular shape in plan view, and preferably has a plate thickness of 0.01 mm to 1.1 mm. If it is 0.01 mm or more, it is difficult to be affected by light interference or internal distortion due to deformation of the glass substrate for display to be evaluated, and if it is 1.1 mm or less, the luminance at the time of evaluation is difficult to decrease. A more preferable plate thickness is 0.1 mm to 0.7 mm, and a further preferable plate thickness is 0.1 mm to 0.5 mm.

The method of bonding the polarizing plate of the present invention to the liquid crystal display device is not particularly limited, and a polarizing plate having the size of the display surface of the liquid crystal display device may be prepared and bonded to both surfaces of the liquid crystal cell. .
As a method for bonding the polarizing plate of the present invention to a liquid crystal display device, a roll-to-panel manufacturing method can also be used, which is preferable for improving productivity and yield. The roll-to-panel manufacturing method is described in JP2011-48381, JP2009-175653, JP4628488, JP4729647, WO2012 / 014602, WO2012 / 014571, etc. It is not limited to this.

Moreover, the method of laminating the polarizing plate of the present invention to the liquid crystal display device uses a roll around which the strip-shaped sheet-like product of the first polarizing plate having a width corresponding to the short side of the display surface of the liquid crystal display device is wound. A first cutting and bonding step of cutting the first polarizing plate to a length corresponding to the long side of the display surface of the liquid crystal display device, and then bonding the first polarizing plate to one display surface of the liquid crystal cell of the liquid crystal display device; Using a roll around which a strip-like sheet-like product of a second polarizing plate having a width corresponding to the long side of the display surface of the device is wound, the length corresponding to the short side of the display surface of the liquid crystal display device is set. After the two polarizing plates are cut, a bonding method including a second cutting and bonding step of bonding to the other surface of the liquid crystal cell of the liquid crystal display device may be used.
According to the above method, by using a polarizing plate roll having a width corresponding to the short side of the display surface of the liquid crystal display device and a polarizing plate roll having a width corresponding to the long side, Polarizers corresponding to the short side and the long side of the display surface of the liquid crystal display device can be obtained only by cutting at regular intervals. For this reason, the former is cut to a length corresponding to the long side, the latter is cut to a length corresponding to the short side, and bonded to both surfaces of the liquid crystal cell of the liquid crystal display device. Using two rolls having the same anisotropy, the upper and lower polarizing plates can be bonded to the liquid crystal cell so that the optical anisotropy such as the absorption axis is orthogonal.

  Further, in the bonding by the above method, the strip-shaped sheet product is pulled out from the supply device of the liquid crystal cell that supplies the liquid crystal cell and the roll on which the strip-shaped sheet-shaped product of the first polarizing plate is wound up to a predetermined length. The first polarizing plate supplied from the first polarizing plate supply device is attached to one surface of the supply device of the first polarizing plate supplied after cutting and the liquid crystal cell supplied from the supply device of the liquid crystal cell. A first sheet bonding device to be combined, a conveyance supply device for conveying and supplying the liquid crystal cell after the first polarizing plate is bonded, and a belt-shaped sheet shape from a roll on which the belt-shaped sheet-shaped product of the second polarizing plate is wound A second polarizing plate supply device that is supplied after the product is pulled out and cut to a predetermined length, and supplied from the second polarizing plate supply device to the other surface of the liquid crystal cell supplied from the transport supply device Pasted the second polarizing plate A first laminating device, and the first polarizing plate supply device and the second polarizing plate supply device correspond to the long side and the short side of the liquid crystal cell, and one of the supply devices is short. A polarizing plate having a width corresponding to the side is cut by a length corresponding to the long side, and the other supply device is configured to cut a polarizing plate having a width corresponding to the long side by a length corresponding to the short side. It is preferable to use a bonding system characterized by being.

[Production of Film 1]
[Acrylic resin having a lactone ring structure represented by the following formula (1) {Mass ratio of copolymerization monomer = methyl methacrylate / 2- (hydroxymethyl) methyl acrylate = 8/2, lactone cyclization rate of about 100% , Lactone ring structure content 19.4 mass%, weight average molecular weight 133000, melt flow rate 6.5 g / 10 min (240 ° C., 10 kgf), Tg 131 ° C.} 90 parts by mass, acrylonitrile-styrene (AS) resin { Toyo AS AS20, manufactured by Toyo Styrene Co., Ltd.} mixture of 10 parts by mass; Tg127 ° C. pellets are fed to a twin screw extruder, melt extruded into a sheet at about 280 ° C., conveyed at high tension and rolled. And a long film 1 having a thickness of 40 μm was obtained.

In the above (1), R ¹ is a hydrogen atom, and R ² and R ³ are methyl groups.

[Preparation of films 2 to 4 and 19]
A film 2 was produced by stretching a 115 μm unstretched sheet produced in the same manner as the film 1 by 3.0 times in the MD direction at 160 ° C. except that the thickness of the melt extrusion was changed. . Furthermore, the long film 3 shown in Table 1 is stretched at a high temperature by stretching a raw film produced under the same conditions as the film 1 except that the thickness of the melt-extruded long unstretched sheet is changed. 4 and 19 were made. In addition, the tensile elasticity modulus of MD direction can be made high by making the draw ratio of MD direction high.

[Production of Film 5]
An imidized resin was obtained by the method of [0173] to [0176] of JP2011-138119A. The imidized resin is an acrylic resin having a glutarimide ring structure in the main chain and not having an aromatic vinyl structure.

100 parts by mass of the imidized resin obtained and 0.10 parts by mass of the following triazine compound A were pelletized using a single screw extruder.
The prepared imidized resin pellets were supplied to a biaxial extruder, melted and extruded into a sheet shape, conveyed by high tension, and wound up to obtain a long film 5 having a thickness of 40 μm.
Triazine compound A

  Me represents a methyl group, and Hx represents a hexyl group.

[Production of Film 6]
Except that the thickness of the melt-extruded long unstretched sheet was changed, the original film prepared under the same conditions as the film 5 was stretched at a high temperature to produce the long film 6 shown in Table 1. did.

[Production of Film 7]
PMMA (polymethyl methacrylate) resin (Delpet 80N manufactured by Asahi Kasei Chemicals Corporation) is dried with a 90 ° C. vacuum dryer to a moisture content of 0.03% or less, and then PMMA (polymethyl methacrylate) resin. For 100 parts by mass, 1.0 part by mass of UV absorber (ADEKA STAB LA-31 manufactured by ADEKA Co., Ltd.) PMMA resin pellets 7 were prepared by mixing at 230 ° C. with a kneader.

  The PMMA resin pellets 7 produced above were melt-extruded from a coat hanger type T die using a twin screw extruder, wound up after being transported with high tension, and a long film 7 having a thickness of 30 μm was obtained. .

[Production of Films 8 to 11]
Except for changing the thickness of the melt-extruded long unstretched sheet, the long films 8 to 11 shown in Table 1 are stretched at a high temperature by stretching a film prepared under the same conditions as the film 7. Was made.

[Production of Film 12]
A commercially available cellulose acetate film (Fujitac TD60, manufactured by Fuji Film Co., Ltd.) was prepared and used as the film 12.

[Production of Film 13]
A commercially available norbornene polymer film “ZEONOR ZF14-060” (manufactured by Optes Co., Ltd.) was prepared and used as the film 13.

[Production of Film 14]
(Synthesis of raw material polyester)
(Raw material polyester 1)
As shown below, terephthalic acid and ethylene glycol are directly reacted to distill off water, esterify, and then use a direct esterification method in which polycondensation is performed under reduced pressure, and a polyester (Sb catalyst) by a continuous polymerization apparatus. System PET) was obtained.

(1) Esterification reaction In a first esterification reactor, 4.7 tons of high-purity terephthalic acid and 1.8 tons of ethylene glycol are mixed over 90 minutes to form a slurry, and continuously at a flow rate of 3800 kg / h. It supplied to the 1st esterification reaction tank. Further, an ethylene glycol solution of antimony trioxide was continuously supplied, and the reaction was carried out at a reaction vessel temperature of 250 ° C. with stirring and an average residence time of about 4.3 hours. At this time, antimony trioxide was continuously added so that the amount of Sb added was 150 ppm in terms of element.

  This reaction product was transferred to a second esterification reaction vessel, and reacted with stirring at a temperature in the reaction vessel of 250 ° C. and an average residence time of 1.2 hours. To the second esterification reaction tank, an ethylene glycol solution of magnesium acetate and an ethylene glycol solution of trimethyl phosphate are continuously supplied so that the added amount of Mg and the added amount of P are 65 ppm and 35 ppm in terms of element, respectively. did.

(2) the polycondensation reaction above-obtained esterification reaction product supplied to the first polycondensation reaction vessel continuously stirring, the reaction temperature 270 ° C., the reaction vessel pressure 20 torr (2.67 × 10 ^{- 3} MPa) and polycondensation with an average residence time of about 1.8 hours.

Further, the mixture was transferred to the second double condensation reaction tank, and while stirring in this reaction tank, the reaction tank temperature was 276 ° C., the reaction tank pressure was 5 torr (6.67 × 10 ⁻⁴ MPa), and the residence time was about 1.2 hours. The reaction (polycondensation) was performed under the conditions.

Subsequently, it was further transferred to the third triple condensation reaction tank. In this reaction tank, the reaction tank temperature was 278 ° C., the reaction tank pressure was 1.5 torr (2.0 × 10 ⁻⁴ MPa), and the residence time was 1.5 hours. The reaction product (polyethylene terephthalate (PET)) was obtained by reaction (polycondensation) under the following conditions.

  Next, the obtained reaction product was discharged into cold water in a strand form and immediately cut to prepare polyester pellets (cross section: major axis: about 4 mm, minor axis: about 2 mm, length: about 3 mm).

  The obtained polymer had IV = 0.63 (hereinafter abbreviated as PET1).

(Raw material polyester 2)
Dried ultraviolet absorber (2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one) 10 parts by mass, PET1 (IV = 0.63) 90 parts by mass And a raw material polyester 2 containing an ultraviolet absorber was obtained using a kneading extruder (hereinafter abbreviated as PET2).

(Film forming process)
After drying 90 parts by mass of the raw material polyester 1 (PET1) and 10 parts by mass of the raw material polyester 2 (PET2) containing an ultraviolet absorber to a moisture content of 20 ppm or less, the hopper 1 of the uniaxial kneading extruder 1 having a diameter of 50 mm is used. And melted at 300 ° C. with the extruder 1. Extrusion was performed from a die through a gear pump and a filter (pore diameter: 20 μm) under the following extrusion conditions.
The molten resin was extruded from the die under the conditions that the pressure fluctuation was 1% and the temperature distribution of the molten resin was 2%. Specifically, the back pressure was increased by 1% with respect to the average pressure in the barrel of the extruder, and the piping temperature of the extruder was heated at a temperature 2% higher than the average temperature in the barrel of the extruder.
The molten resin extruded from the die was extruded onto a cooling cast drum set at a temperature of 25 ° C., and was brought into close contact with the cooling cast drum using an electrostatic application method. It peeled using the peeling roll arrange | positioned facing the cooling cast drum, and obtained the unstretched polyester film.

(Horizontal stretching process)
The unstretched polyester film was guided to a tenter (lateral stretching machine), and was stretched laterally by the following method and conditions while holding the end of the film with a clip.

(Preheating part)
The preheating temperature was set to 95 ° C., and the mixture was heated to a temperature at which stretching was possible.

(Extension part)
The preheated unstretched polyester film was horizontally stretched in the width direction under the following conditions.
<Condition>
-Transverse stretching temperature: 95 ° C
・ Horizontal stretch ratio: 4.7 times

(Heat fixing part)
Next, a heat setting treatment was performed while controlling the film surface temperature of the polyester film within the following range.
<Condition>
・ Heat setting temperature: 180 ℃
・ Heat setting time: 15 seconds

(Heat relaxation part)
The polyester film after heat setting was heated to the following temperature to relax the film.
-Thermal relaxation temperature: 170 ° C
-Thermal relaxation rate: TD direction (film width direction) 2%

(Cooling section)
Next, the polyester film after heat relaxation was cooled at a cooling temperature of 50 ° C.

(Recovery of film)
After cooling, both ends of the polyester film were trimmed by 20 cm. Then, after extruding (knurling) at a width of 10 mm at both ends, it was wound up with a tension of 18 kg / m.
Thus, a polyester polymer film 14 having a thickness of 60 μm was obtained.

[Production of Film 15]
A commercially available cellulose acylate film ZRD40 (manufactured by Fuji Film Co., Ltd.) was prepared and used as the film 15. The film thickness of the film 15 was 41 μm.

[Production of Film 16]
(Preparation of cellulose acylate)
Cellulose acylate was synthesized by the method described in JP-A-10-45804 and 08-231761, and the degree of substitution was measured. Specifically, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, carboxylic acid serving as a raw material for the acyl substituent was added, and an acylation reaction was performed at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. In addition, aging was performed at 40 ° C. after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone.

(Preparation of cellulose acylate solution for low substitution layer)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution.
Cellulose acetate (substitution degree 2.45) 100.0 parts by mass
The following optical expression agent B 1.3 mass parts The following additive (polycondensation ester of carboxylic acid and diol) 18.5 mass parts
365.5 parts by mass of methylene chloride
Methanol 54.6 parts by mass

(Preparation of cellulose acylate solution for high substitution layer)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution.
Cellulose acetate (substitution degree 2.79) 100.0 parts by mass
The following additives (polycondensation ester of carboxylic acid and diol) 11.3 parts by mass Silica fine particles R972 (manufactured by Nippon Aerosil) 0.15 parts by mass
Methylene chloride 395.0 parts by mass
Methanol 59.0 parts by mass

  Optical developer B

  Polycondensation ester: Polycondensation ester of terephthalic acid or succinic acid as dicarboxylic acid with ethylene glycol or 1,2-propylene glycol as diol (terephthalic acid: phthalic acid: ethylene glycol: 1,2-propylene glycol = 55 : 45: 50: 50 (molar ratio)) (terminal: acetyl group, molecular weight 800)

(Creation of cellulose acylate film)
The cellulose acylate solution for the low substitution layer is a core layer having a film thickness of 36 μm, and the cellulose acylate solution for the high substitution layer is a skin layer having a film thickness of 2 μm on both sides of the core layer. Each was cast. The obtained web (film) was peeled from the band, sandwiched between clips, and stretched by 14% using a tenter at 130 ° C. when the residual solvent amount relative to the mass of the entire film was 20 to 5%. Thereafter, the clip was removed from the film, dried at 130 ° C. for 20 minutes, and further stretched by 27% again at 180 ° C. using a tenter.
The residual solvent amount was determined according to the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is a mass of the web at an arbitrary time point, and N is a mass when the web of which M is measured is dried at 120 ° C. for 2 hours.
Thus, a thermoplastic resin film 16 was obtained (film thickness 40 μm, Re = 50 nm, Rth = 120 nm).

[Preparation of Film 17]
<Preparation of cellulose acylate solution>
Cellulose acylate and the following composition were put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution 17.
――――――――――――――――――――――――――――――――――――――
Cellulose acylate solution 17 composition ――――――――――――――――――――――――――――――――――――――
Cellulose acylate having an acetyl substitution degree of 1.6 and a propionyl substitution degree of 0.9
100.0 parts by mass
Sucrose benzoate Substitution degree of benzoate 6.0 8.0 parts by mass
The following additives (polycondensation ester of carboxylic acid and diol) 2.0 parts by mass
Methylene chloride (first solvent) 400.0 parts by mass
40.0 parts by mass of ethanol (second solvent)
――――――――――――――――――――――――――――――――――――――

  Polycondensation ester: Polycondensation ester of terephthalic acid or adipic acid as dicarboxylic acid with ethylene glycol or 1,2-propylene glycol as diol (terephthalic acid :: adipic acid: ethylene glycol: 1,2-propylene glycol = 55: 45: 50: 50 (molar ratio)) (terminal: acetyl group, molecular weight 1200)

<Preparation of matting agent solution>
The following composition was charged into a disperser and stirred to dissolve each component to prepare a matting agent solution.
――――――――――――――――――――――――――――――――――――――
Composition of matting agent solution
――――――――――――――――――――――――――――――――――――――
Silica particles with an average particle size of 16 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
1.6 parts by mass
Methylene chloride (first solvent) 78.9 parts by mass
Ethanol (second solvent) 8.8 parts by mass
Cellulose acylate solution 17 0.3 parts by mass
――――――――――――――――――――――――――――――――――――――

  After filtration of 1.0 part by mass of the matting agent solution, 92.7 parts by mass of cellulose acylate solution 17 is added, mixed using an in-line mixer, cast using a band casting machine, and immediately after drying air The film was dried by drying to a residual solvent content of 40% at a temperature of 30 ° C. and a drying air speed of 1.4 m / s. The drying air was a fresh air having an organic solvent concentration of 1% or less. A film having a residual solvent content of 15% at an ambient temperature of 130 ° C. was transversely stretched using a tenter at a stretching ratio of 1.36 times and a stretching speed of 150% / min, and then held at 130 ° C. for 30 seconds. Then, the clip was removed and dried at 120 ° C. for 40 minutes to obtain a thermoplastic resin film 17 having a width of 2000 mm (film thickness 40 μm, Re = 50 nm, Rth = 120 nm).

[Production of Film 18]
“Zeonor 1420 R” (manufactured by Nippon Zeon Co., Ltd., thickness 100 μm) was longitudinally stretched at a supply temperature of 140 ° C. and a film film surface temperature of 130 ° C. at a stretching ratio of 33% in a longitudinal uniaxial stretching machine. Then, in a tenter stretching machine, the film is stretched horizontally at an air supply temperature of 140 ° C. and a film film surface temperature of 130 ° C. at a stretching ratio of 45%, and both ends are cut off in front of the winding portion to a width of 1500 mm and wound as a roll film having a length of 4000 m. A biaxially stretched thermoplastic resin film 18 was obtained (film thickness 40 μm, Re = 50 nm, Rth = 120 nm).

  Here, the film thickness [μm], [GPa], the humidity dimensional change rate [%], and the optical property [nm] were measured as follows.

[Measurement of film thickness]
A sample of 5 cm square was prepared and allowed to stand in an environment of 25 ° C. and 60% relative humidity for 48 hours, and the average value obtained by measuring the film thickness at 6 points in the plane was used as the film thickness.

[Measurement of tensile modulus]
For the tensile modulus (GPa), a sample having a length of 200 mm in the measurement direction and a width of 10 mm is prepared, and left for 48 hours in an environment of 25 ° C. and 60% relative humidity, and then the Toyo Seiki Strograph V10-C is used. It was installed so that the chuck interval in the longitudinal direction was 100 mm, a load was applied so that the chuck interval was widened at a stretching speed of 10 mm / min, and the force at that time was measured. The tensile elastic modulus was calculated from the thickness, force, and elongation of the film previously measured with a micrometer.

[Measurement of humidity dimensional change rate]
A sample having a length of 12 cm (measurement direction) and a width of 3 cm is prepared, and pin holes are formed in the sample at an interval of 10 cm in an environment of 25 ° C. and a relative humidity of 60%, and the sample is placed in an environment of 25 ° C. and a relative humidity of 80%. Pin hole interval measured after standing for a period of time (measured value was L80) and pin hole interval measured after the sample was left in an environment of 25 ° C. and 10% relative humidity for 48 hours (measured value was L10) And measured with a pin gauge. Using these measured values, the humidity dimensional change rate of each film was calculated by the following formula.
Film humidity change rate [%] = {(L80 [cm] -L10 [cm]) / 10 [cm]} × 100

[Measurement of optical properties]
Each film is conditioned for 24 hours at 25 ° C. and 60% relative humidity, and is then applied to the film surface at 25 ° C. and 60% relative humidity using an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments). By measuring the phase difference at a wavelength of 590 nm from the direction tilted in increments of 10 ° from + 50 ° to −50 ° from the normal direction of the film with the vertical direction and the slow axis as the rotation axis, the in-plane retardation value (Re) and The retardation value (Rth) in the film thickness direction was calculated.
The direction of the in-plane slow axis corresponds to the direction in which the in-plane refractive index is maximum, and “MD” in Table 1 indicates that the in-plane slow axis is in the direction of ± 5 ° in the MD direction of the film. Indicates that it exists. “TD” in Table 1 indicates that an in-plane slow axis exists in the direction in the range of ± 5 ° in the TD direction of the film.

<Production of films 1 to 14 and 19 with a hard coat layer>

[Preparation of coating composition HCL-1 for forming a hard coat layer]
8 parts by mass of pentaerythritol triacrylate, 0.5 parts by mass of Irgacure 127 (manufactured by BASF), and 4 parts by mass of a bifunctional acrylic compound represented by the following formula C-3 are mixed to form a hard coat layer-forming coating (HCL -1) was prepared.

[Production of hard coat layer]
On the optical films 1 to 14 and 19 produced as described above, a hard coat layer forming coating solution (HCL-1) was applied by a die coating method, dried at 80 ° C. for 5 minutes, and then further subjected to a nitrogen purge under 240 W / Using a “air-cooled metal halide lamp” of cm (manufactured by Eye Graphics Co., Ltd.), the coating layer was cured by irradiating with an irradiation amount of 300 mJ / cm ² to form a hard coat layer having a dry film thickness of 5 μm.
In this way, films 1 to 14 and 19 with a hard coat layer having a hard coat layer on the films 1 to 14 and 19 prepared above were prepared.

<Preparation of polarizing plate>
[Production of polarizer]
A polarizer having a thickness of 20 μm was produced by adsorbing iodine to the stretched polyvinyl alcohol film. In addition, as a manufacturing method of a polarizer, you may use the method of Example 1 of Unexamined-Japanese-Patent No. 2001-141926, for example, or the polarizing film (1) described in Unexamined-Japanese-Patent No. 2013-008019. Alternatively, a PVA layer formed on an amorphous PET substrate may be stretched.

[Production of Polarizing Plate Used for Liquid Crystal Display Device 2]
(Preparation of polarizing plate using bonding method A)
[Adhesive for polarizing plate]
An adhesive for polarizing plate was prepared by blending 100 parts by mass of 2-hydroxyethyl acrylate, 10 parts by mass of tolylene diisocyanate and 3 parts by mass of a photopolymerization initiator (Irgacure 907, manufactured by BASF).

The film 2 with a hard coat layer and the film 2 which are long optical films produced by the method described above are prepared, and the polarizing plate adhesive is placed on the two films with a micro gravure coater (gravure roll: (# 300, rotational speed 140% / line speed) was applied to a thickness of 5 μm to obtain an optical film with an adhesive. Subsequently, it was bonded to both surfaces of the polarizer by roll-to-roll using a roll machine so that the two films with an adhesive sandwich the polarizer having a thickness of 20 μm. Ultraviolet rays were irradiated from the bonded optical film side (both sides) to produce a front-side polarizing plate of the liquid crystal display device 2 in Table 2 described later. The line speed was 20 m / min, and the cumulative amount of ultraviolet light was 300 mJ / cm ² . Here, it arrange | positioned so that the transmission axis of a polarizer and the conveyance direction of a film might orthogonally cross. Similarly, the rear side polarizing plate of the liquid crystal display device 2 of Table 2 described later was manufactured in the same manner as the preparation of the front side polarizing plate except that the film 2 was used instead of the film 2 with a hard coat layer.

[Production of Polarizing Plates Used for Liquid Crystal Display Devices 1, 3-9, 11-18, 20-38]
In preparation of the polarizing plate used for the said liquid crystal display device 2, except having changed the film used for bonding into the combination of following Table 2, it is the same method as the polarizing plate used for the said liquid crystal display device 2. A front-side polarizing plate and a rear-side polarizing plate of each liquid crystal display device were produced. Here, it arrange | positioned so that the transmission axis of a polarizer and the conveyance direction of a film might orthogonally cross.

[Production of Polarizing Plate Used for Liquid Crystal Display Device 10]
(Production of polarizing plate using bonding method B)
Corona treatment was performed on the surfaces of the film 2 with a hard coat layer and the film 2 which are long optical films produced by the above method. Next, using a polyvinyl alcohol adhesive, roll-to-roll is applied to both sides of the polarizer so as to sandwich the 20 μm thick polarizer between the two corona-treated films, at 70 ° C. It dried for 10 minutes or more, and produced the front side polarizing plate of the liquid crystal display device 10 of Table 2 mentioned later. Here, it arrange | positioned so that the transmission axis of a polarizer and the conveyance direction of a film might orthogonally cross. Similarly, a rear side polarizing plate of a liquid crystal display device 10 of Table 2 described later was manufactured in the same manner as the front side polarizing plate except that the film 2 was used instead of the film 2 with a hard coat layer.

[Production of Polarizing Plate Used for Liquid Crystal Display 19]
[Saponification of film]
After preparing the film 12 with a hard coat layer and the film 12 which are long optical films prepared by the above method, and immersing in a 1.5 mol / L NaOH aqueous solution (saponification solution) maintained at 55 ° C. for 2 minutes The film was washed with water and then immersed in a 0.05 mol / L sulfuric acid aqueous solution at 25 ° C. for 30 seconds, and then a water washing bath was passed under running water for 30 seconds to make the film neutral. Then, draining with an air knife was repeated three times, and after dropping the water, the film was retained in a drying zone at 70 ° C. for 15 seconds and dried to produce a saponified film.

  The surface of the film 2 which is a long optical film produced by the above method was subjected to corona treatment. Next, a roll-to-roll roll is used on a roll machine using a polyvinyl alcohol adhesive so that the saponified film 12 with a hard coat layer and the corona-treated film 2 sandwich the polarizer having a thickness of 20 μm. It was bonded to both surfaces of the polarizer and dried at 70 ° C. for 10 minutes or more to prepare a front-side polarizing plate of the liquid crystal display device 19 in Table 2 described later. Here, it arrange | positioned so that the transmission axis of a polarizer and the conveyance direction of a film might orthogonally cross. Similarly, the rear side of the liquid crystal display device 19 of Table 2 described later is performed in the same manner as the front side polarizing plate except that the saponified film 12 is used instead of the saponified film 12 with a hard coat layer. A side polarizing plate was produced.

[Production of liquid crystal display devices 1 to 32]
Two polarizing plates of a commercially available IPS type liquid crystal television (LGLS 42LS5600) are peeled off, and the produced polarizing plates are combined in the combinations shown in Table 2 below, one sheet on the front side and the rear side via an adhesive. I pasted them one by one. The crossed Nicols were arranged so that the absorption axis of the front-side polarizing plate was in the longitudinal direction (left-right direction) and the transmission axis of the rear-side polarizing plate was in the longitudinal direction (left-right direction). The thickness of the glass used for the liquid crystal cell was 0.5 mm. In this manner, liquid crystal display devices 1 to 32 having the configurations shown in Table 2 below were produced.

[Production of liquid crystal display devices 33 to 38]
Two polarizing plates of a commercially available VA type liquid crystal television (Skyworth 39E61HR) are peeled off, and the produced polarizing plates are combined one by one on the front side and the rear side through the adhesive in the combinations shown in Table 2 below. Pasted. The crossed Nicols were arranged so that the absorption axis of the front-side polarizing plate was in the longitudinal direction (left-right direction) and the transmission axis of the rear-side polarizing plate was in the longitudinal direction (left-right direction). The thickness of the glass used for the liquid crystal cell was 0.5 mm. In this manner, liquid crystal display devices 33 to 38 having configurations shown in Table 2 below were produced.

<Evaluation of liquid crystal display device>

(1) Evaluation of display unevenness About the produced liquid crystal display device, after thermostating at 50 ° C. and 80% relative humidity for 72 hours and after leaving at 25 ° C. and 60% relative humidity for 2 hours, the backlight of the liquid crystal display device is turned on and turned on 10 hours later, the light leakage at the four corners of the panel was compared with the reference panel in a dark room to evaluate display unevenness.
In addition, a black display screen is photographed from the front of the screen with the brightness measurement camera “ProMetric” (manufactured by Radiant Imaging) to calculate the average brightness of the entire screen and the brightness difference of the four corners where light leakage is large. Thus, the difference ΔL in light leakage from the reference panel was quantified by the following formula.
ΔL = (light leakage of reference panel) − (light leakage of evaluation panel)
The evaluation results and the reference panel to be compared with each liquid crystal display device are shown in Table 2 below.
A: The light leakage difference with the reference panel can be visually recognized more clearly, and the light leakage reduction effect with respect to the reference panel is greater (0.04 cd / m ² <ΔL).
B: The light leakage difference with the reference panel can be clearly recognized, and the light leakage reduction effect on the reference panel is large (0.03 cd / m ² <ΔL).
C: The difference in light leakage from the reference panel is slightly visible, and there is almost no light leakage reduction effect on the reference panel (0.01 cd / m ² <ΔL ≦ 0.03 cd / m ² ).
D: The difference in light leakage from the reference panel was not visible, and the light leakage reduction effect on the reference panel could not be confirmed (ΔL ≦ 0.01 cd / m ² ).

(2) Evaluation of warpage of liquid crystal cell For the manufactured liquid crystal display device, after thermostating at 50 ° C. and 80% relative humidity for 72 hours and after standing at 25 ° C. and 60% relative humidity for 2 hours, the backlight of the liquid crystal display device is turned on. The liquid crystal cell was taken out after 10 hours from the lighting. The warpage shape of the liquid crystal cell was concave on the viewing side in the longitudinal direction. Subsequently, the liquid crystal cell was fixed in a vertically placed state, and the amount of warpage in the longitudinal direction of the liquid crystal cell was evaluated using a laser displacement meter. Further, the warpage reduction rate with respect to the reference panel was calculated from the warpage amount by the following formula. The evaluation results and the reference panel to be compared with each liquid crystal display device are shown in Table 2 below.
Warpage reduction rate (%) = (warping amount of evaluation panel) / (warping amount of reference panel) × 100

(3) Evaluation of display performance (3) -1 Viewing angle contrast (contrast in oblique direction)
Using a measuring instrument (BM5A, manufactured by TOPCON), in a dark room, the luminance values of black display and white display at 45 degrees and 135 degrees in the azimuth direction are measured at the polar angle direction of 60 degrees from the front of the apparatus, and the viewing angle contrast is measured. (White luminance / Black luminance) was calculated. The viewing angle contrast of the liquid crystal display device was evaluated by the average value of the viewing angle contrast in two directions of 45 degrees and 135 degrees in the azimuth direction. In addition, various images were displayed, and the visibility from the front of the apparatus to the polar angle direction of 60 degrees was subjected to sensory evaluation in two directions of the azimuth angle direction of 45 degrees and 135 degrees.
A: The outline of the video can be clearly seen even in an oblique direction. (Viewing angle contrast is 15 or more)
B: The outline of the image is unclear at 45 degrees or more in the polar angle direction, but the outline of the image is clear up to 45 degrees in the polar angle direction, and there is no practical problem. (View angle contrast is 10 or more and less than 15)
C: The contour of the image in the polar angle direction of 45 degrees is unclear and may cause a problem in practical use. (View angle contrast is less than 10)

(3) -2 Viewing angle color (oblique black)
In the dark room, the color of the black display in the azimuth angle direction of 0 to 360 degrees at the polar angle direction of 60 degrees from the front of the apparatus was sensory evaluated. When yellow or green is mixed with the change in black taste, the display quality deteriorates remarkably, so the criteria for sensory evaluation are set as follows.
A: The black color changes from blue to red, and is acceptable as display quality.
B: Yellow or green is mixed with black and the display quality is extremely poor.

  In Table 2 below, “−” in the column of display performance represents that evaluation was not performed.

According to the study by the present inventors, the value of the ratio obtained by dividing the tensile elastic modulus in the machine direction (MD direction) of the acrylic film made of acrylic resin by the tensile elastic modulus in the direction perpendicular to the machine direction (TD direction). By making the value larger than 1.36, the warpage of the liquid crystal cell can be greatly reduced, and as a result, it has been found that light leakage can be remarkably improved, and the present invention has been completed.
That is, the above problem can be solved by the following means.
<1>
A liquid crystal display device comprising at least a front-side polarizing plate, a liquid crystal cell, and a rear-side polarizing plate,
The polarizing plate on the front side is a polarizer and at least one side of the polarizer,
Made of polymethylmethacrylate, comprising an optical film that satisfactory tensile modulus in the machine direction (MD direction) tensile elastic modulus and the machine direction in a direction perpendicular (TD direction) the relationship of the formula (1),
The liquid crystal display device in which the mechanical direction (MD direction) of the optical film of the front-side polarizing plate is parallel to the direction of the long side of the display surface of the liquid crystal display device.
Formula (1) Tensile modulus in MD direction / Tension modulus in TD direction> 1.36
<2>
The tensile elastic modulus in the machine direction (MD direction) of the optical film is 1.70 × 10 ^{9 to} 5.5 × 10 ⁹ N / m ² , and the tensile elastic modulus in the direction perpendicular to the machine direction (TD direction) is The liquid crystal display device according to <1>, which is 1.2 × 10 ^{9 to} 4.0 × 10 ⁹ N / m ² .
<3>
<1> or <1 < The liquid crystal display device according to 2>.
(I) Re = (nx−ny) × d
(Ii) Rth = ((nx + ny) / 2−nz) × d
(Iii) 0 ≦ Re <20
(Iv) | Rth | ≦ 25
In the formula, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is the film (Nm).
<4>
At least one layer of a pattern retardation layer, a λ / 4 layer, an optically anisotropic layer, a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an easy adhesion layer is provided on the surface of the optical film <1. The liquid crystal display device according to any one of> to <3>.
<5>
The rear polarizing plate is a polarizer and at least on one side of the polarizer,
Comprising the optical film,
The liquid crystal display device according to any one of <1> to <4>, wherein a mechanical direction (MD direction) of the optical film of the rear polarizing plate is parallel to a direction of a short side of the liquid crystal display device.
<6>
The optical film is provided on both surfaces of the polarizer of the front-side polarizing plate,
The liquid crystal display device according to any one of <1> to <5>, wherein a mechanical direction (MD direction) of the optical film is parallel to a direction of a long side of the liquid crystal display device.
<7>
The optical film is provided on both sides of the polarizer of the rear side polarizing plate,
The liquid crystal display device according to <5> or <6>, wherein a mechanical direction (MD direction) of the optical film is parallel to a direction of a short side of the liquid crystal display device.
<8>
The liquid crystal display device according to any one of <1> to <7>, wherein the polarizer and the optical film are bonded with a curable adhesive.
<9>
The liquid crystal display device according to any one of <1> to <8>, wherein the liquid crystal cell is in an IPS mode or a VA mode.
Although this invention is invention which concerns on said <1>-<9>, below, other matters are also described.

Claims (9)

A liquid crystal display device comprising at least a front side polarizing plate, a liquid crystal cell, and a rear side polarizing plate,
The front-side polarizing plate has a polarizer and at least one side of the polarizer,
An optical film having a thickness of 10 to 40 μm made of an acrylic resin and satisfying the relationship of the formula (1) in the tensile modulus in the machine direction (MD direction) and the tensile modulus in the direction perpendicular to the machine direction (TD direction) Comprising
A liquid crystal display device in which a mechanical direction (MD direction) of the optical film of the front side polarizing plate is parallel to a direction of a long side of a display surface of the liquid crystal display device.
Formula (1) Tensile modulus in MD direction / Tension modulus in TD direction> 1.36 The tensile elastic modulus in the machine direction (MD direction) of the optical film is 1.70 × 10 ^{9 to} 5.5 × 10 ⁹ N / m ² , and the tensile elastic modulus in the direction perpendicular to the machine direction (TD direction) is The liquid crystal display device according to claim 1, which is 1.2 × 10 ^{9 to} 4.0 × 10 ⁹ N / m ² . The retardation value Re in the film plane and the retardation value Rth in the film thickness direction represented by the formulas (i) and (ii) of the optical film satisfy the formulas (iii) and (iv). A liquid crystal display device according to 1.
(I) Re = (nx−ny) × d
(Ii) Rth = ((nx + ny) / 2−nz) × d
(Iii) 0 ≦ Re <20
(Iv) | Rth | ≦ 25
In the formula, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is the film (Nm).   The surface of the optical film is provided with at least one of a pattern retardation layer, a λ / 4 layer, an optical anisotropic layer, a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an easy adhesion layer. The liquid crystal display device according to any one of 1 to 3. The rear polarizing plate is a polarizer and at least on one side of the polarizer,
Comprising the optical film,
The liquid crystal display device according to claim 1, wherein a mechanical direction (MD direction) of the optical film of the rear side polarizing plate is parallel to a direction of a short side of the liquid crystal display device. The optical film is provided on both surfaces of the polarizer of the front-side polarizing plate,
The liquid crystal display device according to claim 1, wherein a mechanical direction (MD direction) of the optical film is parallel to a direction of a long side of the liquid crystal display device.   The said optical film is comprised on both surfaces of the polarizer of the said rear side polarizing plate, The machine direction (MD direction) of the said optical film is parallel to the direction of the short side of the said liquid crystal display device. Liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the polarizer and the optical film are bonded with a curable adhesive. The liquid crystal display device according to claim 1, wherein the liquid crystal cell is in an IPS mode or a VA mode.