JP5130958B2 - TN mode liquid crystal display element, manufacturing method thereof, and retardation film for TN mode liquid crystal display element - Google Patents

Description

  The present invention relates to a TN mode liquid crystal display element having a retardation film made of a thermoplastic resin, a method for producing the liquid crystal display element, and a retardation film for a TN mode liquid crystal display element.

In recent years, liquid crystal display elements are required to have a larger size, and display performance with uniform and high contrast over the entire surface of the liquid crystal display element. In addition, display performance with a wider range of viewing angles is required as screens become larger. In order to obtain such a wide viewing angle, generally a polarizing plate having a retardation film and a polarizer. Is provided outside the liquid crystal cell to provide a viewing angle compensation function.
In a TN mode liquid crystal display element, a method of compensating a viewing angle by using a polarizing plate using an optical film coated with a discotic liquid crystal as a retardation film is generally used.

  However, the retardation film in the polarizing plate described above has a problem that the optical axis tends to be non-uniform because it coats liquid crystal. In addition, there is a problem that defects on the film surface are likely to occur due to unevenness during coating or contamination with foreign matter. Such film optical axis non-uniformity and in-plane non-uniformity lead to non-uniformity in display characteristics, particularly generation of bright spots that are display defects.

  The inventors of the present invention use the retardation film having specific optical characteristics that are highly controlled in the optical axis by the stretching process, so that no defects due to the inclusion of foreign matter occur, and therefore, in the liquid crystal display element surface. It has been found that a wide range of viewing angle compensation can be achieved without generating bright spots. It is an object of the present invention to provide a TN mode liquid crystal display element that does not generate a bright spot and has excellent viewing angle characteristics over a wide range.

TN mode liquid crystal display device of the present invention (hereinafter, simply referred to as "LCD device") is two polarizing plates having a polarizer and a retardation film composed of a thermoplastic resin, sandwiching a liquid crystal cell Each of the retardation films constituting each polarizing plate satisfies the following formulas (i) and (ii).
(I) 20 nm ≦ R0 ≦ 150 nm
(Ii) 1.1 ≦ NZ ≦ 4.3
(Where R0 represents the retardation in the film plane, NZ represents the NZ coefficient, nx represents the maximum refractive index in the film plane at a light wavelength of 550 nm, and the refractive index in the direction perpendicular to nx in the film plane) Is ny, the refractive index in the film thickness direction is nz, and the thickness is d (nm), and is calculated by the formula R0 = (nx−ny) × d and the formula NZ = (nx−nz) / (nx−ny). Value.)

The liquid crystal display device of the present invention, two polarizing plates, sandwiching the liquid crystal cell is disposed on the rear side and the viewer side of the liquid crystal display device, the retardation film constituting the respective polarizing plates, the following formula It is preferable to satisfy (iii).
(Iii) 200 nm ≦ R0f × NZf + R0r × NZr ≦ 260 nm
(Here, R0f and NZf respectively represent R0 and NZ of the optical film on the viewer side of the liquid crystal display element, and R0r and NZr respectively represent R0 and NZ of the optical film on the back side of the liquid crystal display element.)

In the liquid crystal display element of the present invention, the retardation film preferably satisfies the following formulas (iv) and (v).
(Iv) 70 nm ≦ R0 ≦ 150 nm
(V) 1.1 ≦ NZ ≦ 1.5
In the liquid crystal display element of the present invention, the thermoplastic resin constituting the retardation film is preferably a cyclic olefin resin having a repeating unit represented by the following formula (I).

[In the formula (I), m is an integer of 1 or more, p is 0 or an integer of 1 or more, D is a group represented by —CH═CH— or —CH ₂ CH ₂ —, R ^{1 to} R ⁴ are each independently a hydrogen atom; a halogen atom; a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms; a polar group R ¹ and R ² may be combined to form a divalent hydrocarbon group, and R ³ and R ⁴ may be combined to form a divalent hydrocarbon group. May be. R ¹ and R ² may be bonded to each other to form a carbocyclic or heterocyclic ring, and R ³ and R ⁴ may be bonded to each other to form a carbocyclic or heterocyclic ring. May be monocyclic or polycyclic. ]

Furthermore, in the liquid crystal display element of the present invention, the polarizing plate preferably has a protective film.
The method for producing a liquid crystal display element of the present invention includes a step of drawing a retardation film satisfying the formulas (i) and (ii) by stretching a raw film made of a thermoplastic resin, and the retardation film. It has the process of superimposing a polarizer and producing a polarizing plate, and the process of superimposing the obtained polarizing plate on a liquid crystal cell, It is characterized by the above-mentioned.
The retardation film for a TN mode liquid crystal display element of the present invention (hereinafter, also simply referred to as “retardation film”) is obtained by stretching a raw film composed of a thermoplastic resin, and the above formulas (i) and ( It fulfills ii).

  According to the present invention, a TN mode liquid crystal display element that does not generate a bright spot, can achieve excellent viewing angle characteristics over a wide range, has no display unevenness, and exhibits stable display characteristics, a manufacturing method thereof, and the liquid crystal display element The retardation film for a TN mode liquid crystal display element used for the TN mode and having high optical performance control over the entire surface can be provided.

Hereinafter, the present invention will be specifically described.
<Thermoplastic resin>
The thermoplastic resin constituting the retardation film according to the present invention preferably has transparency and heat resistance, and has a glass transition temperature of 120 ° C. or higher and a linear expansion coefficient of 7.0 × 10 ⁻⁵ / ° C. or lower. It is preferable. Specific examples include cyclic olefin resins, cellulose resins, polycarbonate (PC), polyarylate (PAR), polysulfone (PSF), polyethersulfone (PES), polyparaphenylene (PPP), polyarylene ether phosphine. Examples thereof include oxide (PEPO), polyimide (PPI), polyetherimide (PEI), and polyamideimide (PAI). Of these, cyclic olefin resins and cellulose resins are preferable, and cyclic olefin resins are more preferable.

  The cyclic olefin resin is not particularly limited, and a ring-opening (co) polymer of a cyclic olefin monomer having a norbornene skeleton, a hydrogenated product of a ring-opening (co) polymer, an addition (co) Examples thereof include a polymer, a copolymer of a cyclic olefin monomer and another copolymerizable monomer, a hydrogenated product thereof, and the like.

  Specifically, a ring-opening (co) polymer of a cyclic olefin-based monomer represented by formula (I ′) and formula (II ′) described later, and a hydride of the ring-opening (co) polymer. , Addition (co) polymers, addition copolymers of cyclic olefin monomers and α-olefins, and the like. Among these, a hydride of a ring-opening (co) polymer is preferable, and a polymer having a repeating unit represented by the formula (I) is particularly preferable. The polymer may be a homopolymer having a repeating unit represented by the formula (I), or a copolymer having a repeating unit represented by the following formula (II) together with the formula (I). There may be.

[In Formula (II), E is a group independently represented by —CH═CH— or —CH ₂ CH ₂ —, and R ^{5 to} R ⁸ each independently represents a hydrogen atom; a halogen atom; an oxygen atom. A linking group containing a sulfur atom, a nitrogen atom or a silicon atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms; a polar group, wherein R ⁵ and R ⁶ are a divalent hydrocarbon group R ⁷ and R ⁸ may be combined to form a divalent hydrocarbon group. R ⁵ or R ⁶ and R ⁷ or R ⁸ may be bonded to each other to form a carbocyclic or heterocyclic ring, and the carbocyclic or heterocyclic ring may be a monocyclic structure or a polycyclic structure. ]

In order to make the glass transition temperature of the cyclic olefin resin suitable for film processing and at the same time to ensure birefringence controllability, m in the formula (I) is preferably 1 to 5, more preferably 1 to 3, and even more preferably. Is 1-2, and p is preferably 0-4, more preferably 0-2, and even more preferably 0-1. The number of carbon atoms of R ^{1 to} R ⁴ is preferably 1 to 25, more preferably 1 to 20, and still more preferably 1 to 10. Furthermore, the number of carbon atoms of R ^{5 to} R ⁸ in the formula (II) is preferably 1 to 25, more preferably 1 to 20.

Method for Producing Cyclic Olefin Resin The cyclic olefin resin according to the present invention has a repeating unit represented by the formula (I) and, if necessary, a repeating unit represented by the formula (II).

  The repeating unit represented by the formula (I) is derived from a cyclic olefin monomer represented by the following formula (I ′) by ring-opening (co) polymerization.

(In formula (I ′), m and R ^{1 to} R ⁴ are the same as those in formula (I).)
In the formula (I) or the formula (I ′), examples of the polar group include a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, a carbonyloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, a cyano group, an amide group, Examples thereof include an imide group, a triorganosiloxy group, a triorganosilyl group, an amino group, an acyl group, an alkoxysilyl group, a sulfonyl group, and a carboxyl group. More specifically, examples of the alkoxy group include a methoxy group and an ethoxy group; examples of the carbonyloxy group include an alkylcarbonyloxy group such as an acetoxy group and a propionyloxy group, and an aryl such as a benzoyloxy group. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group; examples of the aryloxycarbonyl group include a phenoxycarbonyl group, a naphthyloxycarbonyl group, a fluorenyloxycarbonyl group, Examples of the triorganosiloxy group include trimethylsiloxy group and triethylsiloxy group; examples of the triorganosilyl group include trimethyl Silyl groups, such as triethylsilyl group and the like; examples of the amino group include primary amino group, the alkoxysilyl group, for example a trimethoxysilyl group, a triethoxysilyl group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.
Examples of the hydrocarbon group having 1 to 10 carbon atoms include alkyl groups such as methyl group, ethyl group, and propyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; alkenyl groups such as vinyl group, allyl group, and propenyl group. Group and the like.

In addition, the substituted or unsubstituted hydrocarbon group may be directly bonded to the ring structure, or may be bonded via a linking group. Examples of the linking group include a divalent hydrocarbon group having 1 to 10 carbon atoms (for example, an alkylene group represented by — (CH ₂ ) _m — (wherein m is an integer of 1 to 10)); oxygen , A linking group containing nitrogen, sulfur or silicon (for example, a carbonyl group (—CO—), an oxycarbonyl group (—O (CO) —), a sulfone group (—SO ₂ —), an ether bond (—O—), Thioether bond (—S—), imino group (—NH—), amide bond (—NHCO—, —CONH—), siloxane bond (—OSi (R ₂ ) — (wherein R is an alkyl such as methyl or ethyl) Group)) and the like, and a linking group containing a plurality of these may be used.

Specific examples of the cyclic olefin monomer (I ′) include the following compounds.
Tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
Pentacyclo ^{[6.5.1.1 3,6 .0 2,7 .0 9,13]} -4- pentadecene,
8-methyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-ethyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8 methoxycarbonyltetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-ethoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-n-propoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8 isopropoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-n-butoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl-8-ethoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl -8-n-propoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl-8-isopropoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl -8-n-butoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,

8-cyano-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-cyano-8-methyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8 ethylidene tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-phenyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-fluoro-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-fluoro-methyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8 difluoromethyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-trifluoromethyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8 pentafluoroethyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8-difluoro-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,9-difluoro-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl-8-trifluoromethyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9- trifluoro-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9- tris (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9,9- tetrafluoro-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9,9- tetrakis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8-difluoro-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,9-difluoro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9- trifluoro-9-trifluoromethyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9- trifluoro-9-trifluoromethoxy-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9- trifluoro-9-pentafluoro propoxy tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-Fluoro-8-pentafluoroethyl-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,9-difluoro-8-heptafluoroisopropyl-9-trifluoromethyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-Chloro -8,9,9- trifluoro tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,9-dichloro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8- (2,2,2-trifluoroethoxy-carbonyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl-8- (2,2,2-trifluoroethoxy-carbonyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene these, alone or in combination of two or more Can be used together.

In the present invention, the repeating unit represented by the formula (I) preferably has a polar group, and the polar group is preferably a group represented by the following formula (III). That is, in the repeating unit represented by the formula (I) or the cyclic olefin monomer represented by the formula (I ′), at least one of R ^{1 to} R ⁴ is represented by the following formula (III). It is preferably a group.

_{- (CH 2) p COOR '} ... (III)
(In formula (III), p is 0 or an integer of 1 to 5, and R ′ is a hydrocarbon group having 1 to 15 carbon atoms.)
In the formula (III), the smaller the value of p and the smaller the R ′ carbon number, the higher the glass transition temperature of the resulting copolymer and the better the heat resistance. That is, p is usually 0 or an integer of 1 to 5, preferably 0 or 1, and R 'is usually a hydrocarbon group having 1 to 15 carbon atoms, preferably 1 carbon atom. Desirably, it is an alkyl group of ˜3.

  Further, in the formula (I) or (I ′), when an alkyl group is further bonded to the carbon atom to which the polar group represented by the formula (III) is bonded, the heat resistance of the resulting copolymer is increased. And water absorption (wet) properties are preferable. Moreover, it is preferable that the carbon atom number of an alkyl group is 1-5, More preferably, it is 1-2, Most preferably, it is 1.

  The repeating unit represented by the formula (II) is derived from a cyclic olefin monomer (II) represented by the following formula (II ′) by ring-opening copolymerization.

(In Formula (II ′), R ^{5 to} R ⁸ are the same as those in Formula (II).)
Specific examples of such cyclic olefin monomers include the following compounds.
Tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene (dicyclopentadiene),
Bicyclo [2.2.1] hept-2-ene (norbornene),
Bicyclo [2.2.1] hepta-2,5-diene,
5-methylbicyclo [2.2.1] hept-2-ene,
5-ethylbicyclo [2.2.1] hept-2-ene,
5-propylbicyclo [2.2.1] hept-2-ene,
5-butylbicyclo [2.2.1] hept-2-ene,
5-pentylbicyclo [2.2.1] hept-2-ene,
5-hexylbicyclo [2.2.1] hept-2-ene,
5-heptylbicyclo [2.2.1] hept-2-ene,
5-octylbicyclo [2.2.1] hept-2-ene,
5-nonylbicyclo [2.2.1] hept-2-ene,
5-decylbicyclo [2.2.1] hept-2-ene,
5-undecylbicyclo [2.2.1] hept-2-ene,
5-dodecylbicyclo [2.2.1] hept-2-ene,
5-tridecylbicyclo [2.2.1] hept-2-ene,
5-tetradecylbicyclo [2.2.1] hept-2-ene,
5-pentadecylbicyclo [2.2.1] hept-2-ene,
5-hexadecylbicyclo [2.2.1] hept-2-ene,
5-heptadecylbicyclo [2.2.1] hept-2-ene,
5-octadecylbicyclo [2.2.1] hept-2-ene,
5-nonadecylbicyclo [2.2.1] hept-2-ene,
5-icosylbicyclo [2.2.1] hept-2-ene,
5-phenylbicyclo [2.2.1] hept-2-ene,
5-cyanobicyclo [2.2.1] hept-2-ene,
5-methoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-ethoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-methoxycarbonyl-5-methylbicyclo [2.2.1] hept-2-ene,
5-ethoxycarbonyl-5-methylbicyclo [2.2.1] hept-2-ene,
5-cyano-5-methylbicyclo [2.2.1] hept-2-ene 5-ethylidenebicyclo [2.2.1] hept-2-enespiro [fluorene-9,8'-tricyclo [4.3. 0.1 ^2.5 ] [3] Decene]
These can be used alone or in combination of two or more. Of these, tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene and bicyclo [2.2.1] hept-2-ene are preferably used in the present invention.

The cyclic olefin resin according to the present invention can be produced by ring-opening copolymerization of one or more cyclic olefin monomers (I ′) and cyclic olefin monomers (II ′). . The cyclic olefin-based resin according to the present invention is composed of 8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene and at least one selected from tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene and bicyclo [2.2.1] hept-2-ene Particularly preferred is a copolymer comprising seeds.

  In the present invention, the copolymerization ratio of the cyclic olefin monomer (compound represented by formula (I ′)) and the cyclic olefin monomer (compound represented by formula (II ′)) is the sum of these. Is usually 0 to 40 parts by weight, preferably 3 to 30 parts by weight, based on 100 parts by weight of the cyclic olefin monomer (II ′). If the copolymerization ratio of the cyclic olefin monomer (II ′) exceeds 30 parts by weight, the glass transition temperature may be lowered, and the heat resistance stability of various film properties such as retardation and dimensions may be lowered. On the other hand, if it is less than 3 weights, the slidability and retardation development property of the resulting molded article, film or sheet may be lowered.

  In the present invention, in addition to these cyclic olefin monomers (I ′) and (II ′), other cyclic olefin monomers or other copolymerizable monomers may be used as long as the object of the present invention is not impaired. A small amount of a monomer can be used as a copolymer raw material monomer, and the cyclic olefin resin according to the present invention can contain a repeating unit other than the repeating units represented by the formulas (I) and (II). Such repeating units are formed, for example, by ring-opening copolymerization of cycloolefin monomers such as cyclobutene, cyclopentene, cycloheptene, and cyclooctene together with the cyclic olefin monomers (I ′) and (II ′). can do. In addition, in the presence of an unsaturated hydrocarbon polymer having an olefinically unsaturated bond in the main chain, such as polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-nonconjugated diene copolymer, polynorbornene, etc. It can also be formed by ring-opening copolymerization of the olefinic monomers (I ′) and (II ′), and when having such a repeating unit, the impact resistance of the copolymer of the present invention is as follows. Tend to be improved.

  However, in the present invention, it is preferable to carry out copolymerization using only the cyclic olefinic monomers (I ′) and (II ′). That is, the cyclic olefin resin according to the present invention may have other repeating units within a range not impairing the object of the present invention in addition to the repeating units represented by the formulas (I) and (II). However, it is preferable that there is no repeating unit other than the repeating units represented by the formulas (I) and (II).

  A ring-opening copolymer obtained by ring-opening copolymerization of each cyclic olefin monomer has an olefinic unsaturated bond in the molecule and has problems such as heat-resistant coloring. The olefinically unsaturated bond is preferably hydrogenated, but a known method can be applied to the hydrogenation reaction.

  For example, the catalyst, solvent, temperature conditions, etc. described in JP-A-63-218726, JP-A-1-132626, JP-A-1-240517, JP-A-2-10221 and the like are applied. The ring-opening polymerization reaction and the hydrogenation reaction can be carried out.

  The hydrogenation rate of the olefinically unsaturated bond is usually 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 99 mol% or more. As described above, the hydrogenation reaction in the present invention is for olefinic unsaturated bonds in the molecule, and when the cyclic olefin resin according to the present invention has an aromatic group, the aromatic group is refracted. Since there may be an advantageous effect on optical characteristics such as the rate and heat resistance, hydrogenation is not necessarily required.

As the molecular weight of the cyclic olefin resin according to the present invention, the polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is usually 3 × 10 ^{3 to} 5 × 10 ⁵ , preferably 5 × 10 ^{3 to} 3 × 10 ⁵ , more preferably 1 × 10 ⁴ to 2 × 10 ⁵ , and the weight average molecular weight (Mw) in terms of polystyrene is usually 5 × 10 ³ to 1 × 10 ⁶ , preferably It is desirable to be in the range of 1 × 10 ^{4 to} 5 × 10 ⁵ , more preferably 2 × 10 ⁴ to 4 × 10 ⁵ .

  If the molecular weight is too small, the strength of the resulting film may be low, or the retardation development property during stretching may be reduced. On the other hand, when the molecular weight is excessive, the solution viscosity and the melt viscosity become too high, and the productivity and processability of the copolymer of the present invention may be deteriorated.

The molecular weight distribution (Mw / Mn) of the cyclic olefin-based resin according to the present invention is usually 1.5 to 10, preferably 2 to 7, and more preferably 2 to 5.
The cyclic olefin resin according to the present invention has a saturated water absorption at 23 ° C. of usually 0.05 to 1% by weight, preferably 0.07 to 0.8% by weight, and more preferably 0.1 to 0.7% by weight. % Is desirable. If the saturated water absorption of the cyclic olefin-based resin according to the present invention is within the above range, various optical properties, transparency, retardation and retardation uniformity, or dimensional accuracy of the obtained film are high temperature and high humidity. In addition to being stably maintained even under such conditions, it is excellent in adhesion and adhesion to other materials, so that peeling does not occur during use, and it is compatible with additives such as antioxidants. Since solubility is also favorable, the freedom degree of selection of the kind and addition amount of an additive becomes large.

  When this saturated water absorption is less than 0.05% by weight, the resulting film has low adhesion and adhesiveness to other materials, tends to cause peeling during use, and an antioxidant. The amount of additives such as these may be limited. On the other hand, when the saturated water absorption exceeds 1% by weight, the water absorption tends to cause changes in optical characteristics and dimensional changes.

Here, the saturated water absorption is a value obtained by immersing in water at 23 ° C. for 1 week and measuring an increased weight in accordance with ASTM D570.
The glass transition temperature (Tg) of the cyclic olefin resin according to the present invention is usually 70 to 250 ° C, preferably 90 to 200 ° C, more preferably 100 to 180 ° C. A Tg of 120 ° C. or higher is preferable because of having excellent heat resistance. When Tg is less than 90 ° C., the heat distortion temperature becomes low, which may cause a problem in heat resistance, and a problem that a change in optical characteristics due to temperature in the obtained film becomes large may occur. is there. On the other hand, when Tg exceeds 200 ° C., the processing temperature becomes too high during the stretching process, and the copolymer of the present invention may be thermally deteriorated, and productivity and workability may be deteriorated.

  In this specification, the Tg of a thermoplastic resin (for example, a cyclic olefin resin) is a differential differential obtained when a differential scanning calorimeter (DSC) is used and measured at a heating rate of 20 ° C./min in a nitrogen atmosphere. The maximum peak temperature (point A) of the scanning calorie curve and the temperature (point B) of −20 ° C. from the maximum peak temperature are plotted on the differential scanning calorie curve, and the tangent and A point on the baseline starting from point B It is obtained as the intersection with the starting tangent.

Polymerization catalyst Examples of the catalyst used for the production of the cyclic olefin resin according to the present invention include:
A catalyst described in Olefin Metathesis and Metathesis Polymerization (KJIVIN, JCMOL, Academic Press 1997) is preferably used. Examples of such a catalyst include (i) (a) at least one selected from compounds of W, Mo, Re, V and Ti, and (b) an alkali metal element (for example, Li, Na, K). , Alkaline earth metal elements (for example, Mg, Ca), Group 12 elements (for example, Zn, Cd, Hg), Group 13 elements (for example, B, Al), Group 14 elements (for example, Si, Sn) , Pd) and the like, and a metathesis catalyst comprising a combination with at least one selected from those having at least one of the element-carbon bond or the element-hydrogen bond. In order to enhance the activity of the catalyst, the additive (c) described later may be added.

Specific examples of the component (a) include compounds described in JP-A-1-240517 such as WCl ₆ , MoCl ₅ , ReOCl ₃ , VOCl ₃ and TiCl ₄ . These can be used singly or in combination of two or more.

Specific examples of the component (b) include, for example, n-C ₄ H ₉ Li, (C ₂ H ₅ ) ₃ Al, (C ₂ H ₅ ) ₂ AlCl, (C ₂ H ₅ ) _1.5 AlCl _1.5 , ( Examples thereof include compounds described in JP-A-1-240517 such as C ₂ H ₅ ) AlCl ₂ , methylaluminoxane, LiH. These can be used singly or in combination of two or more.

As the additive of the component (c), for example, alcohols, aldehydes, ketones, amines and the like can be preferably used, and further, compounds described in JP-A-1-240517 can be used. Can do. These can be used singly or in combination of two or more.

  The amount of the metathesis catalyst used in combination with the component (a) is such that the molar ratio of “component (a): total monomer” between the component (a) and the total monomer is usually 1 : 500 to 1: 500,000, preferably 1: 1,000 to 1: 100,000. Further, the ratio of the component (a) to the component (b) is such that the metal atom (mole) ratio of “(a) :( b)” is usually 1: 1 to 1:50, preferably 1: 2. It is in the range of ˜1: 30. When the additive (c) is added to this metathesis catalyst, the ratio of the component (a) to the component (c) is such that the molar ratio of “(c) :( a)” is usually 0.005: 1 to The range is 15: 1, preferably 0.05: 1 to 7: 1.

As other catalysts,
(Ii) A metathesis catalyst comprising a transition metal-carbene complex or a metallacyclobutane complex belonging to Groups 4 to 8 of the periodic table can be used.

Specific examples of the catalyst (ii) include, for example, W (= N-2,6-C ₆ H ₃ ⁱ Pr ₂ ) (= CH ^tert Bu) (O ^tert Bu) ₂ , Mo (= N-2, 6-C ₆ H ₃ ⁱ Pr ₂ ) (═CH ^tert Bu) (O ^tert Bu) ₂ , Ru (═CHCH═CPh ₂ ) (PPh ₃ ) ₂ Cl ₂ , Ru (═CHPh ₂ ) [P (C ₆ H ₁₁ ) ₃ ] ₂ Cl ₂ , Ru (= CHPh) [P (C ₆ H ₁₁ ) ₃ ] ₂ Cl _{2 and the} like. These can be used singly or in combination of two or more.

  The amount of the catalyst (ii) used is such that the molar ratio of “catalyst (ii): total monomer” is usually 1: 500 to 1: 50,000, preferably 1: 100 to 1:10, 000.

The catalysts (i) and (ii) may be used in combination.
The molecular weight of the copolymer used in the present invention can be adjusted by adjusting the polymerization temperature, the type of catalyst, the type of solvent, etc., but the molecular weight regulator is allowed to coexist in the reaction system for ring-opening copolymerization. It is preferable to adjust by this. As the molecular weight regulator, for example, α-olefins such as ethylene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and styrene are preferable, Of these, 1-butene and 1-hexene are particularly preferred. These molecular weight regulators can be used singly or in combination of two or more. The amount of the molecular weight regulator used is usually 0.005 to 0.6 mol, preferably 0.02 to 0.5 mol, per mol of all monomers.

Examples of the solvent used in the ring-opening copolymerization reaction (that is, a solvent that dissolves a monomer, a ring-opening polymerization catalyst, a molecular weight regulator, etc.) include alkanes such as pentane, hexane, heptane, octane, nonane, and decane. Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene; chlorobutane, bromohexane, methylene chloride, dichloroethane, hexamethylene dibromide, chlorobenzene , chloroform, halogenated alkanes, such as tetrachlorethylene, compounds such as aryl halides, ethyl acetate, n- butyl, isobutyl acetate, saturated carboxylic acid esters such as methyl propionate; dibutyl ether Tetrahydrofuran, include ethers such as dimethoxyethane, aromatic hydrocarbons are preferred among these. These can be used singly or in combination of two or more. The use amount of the solvent for the ring-opening polymerization reaction is such that the weight ratio of “solvent: total monomer” is usually 1: 1 to 10: 1, preferably 1: 1 to 5: 1. Is desirable.

  The temperature of the monomer solution when adding the catalyst is preferably 30 to 200 ° C, more preferably 50 to 180 ° C. When the temperature is lower than 30 ° C, the yield of the polymer may be lowered, and when it exceeds 200 ° C, it may be difficult to control the molecular weight.

The reaction time for carrying out the ring-opening copolymerization reaction is usually 0.1 to 10 hours, preferably 0.1 to 9 hours, more preferably 0.1 to 8 hours.
A ring-opening copolymer obtained by ring-opening copolymerization of each cyclic olefin monomer has an olefinic unsaturated bond in the molecule and has problems such as heat-resistant coloring. The olefinically unsaturated bond is preferably hydrogenated. The hydrogenation method and the preferred hydrogenation rate are as described above.

<Additives>
Various additives can be blended in the cyclic olefin resin thermoplastic resin according to the present invention as required. For example, an antioxidant selected from a phenolic antioxidant, a lactone antioxidant, a phosphorus antioxidant and a sulfur antioxidant may be added to improve oxidation stability and prevent coloring and deterioration. it can.

The antioxidant may be blended at a ratio of 0.001 to 5 parts by weight per 100 parts by weight of the polymer. Specific examples of antioxidants include
1) 2,6-di-tert-butyl-4-methylphenol, 4,4′-thiobis- (6-tert-butyl-3-methyl-phenyl), 1,1-bis (4-hydroxyphenyl) cyclohexane , 2,2'-methylenebis (4-ethyl -6-tert-butylphenol), tetrakis [methylene-3- (3,5-di -tert- butyl-4-hydroxyphenyl) propionate] methane, 3- (3, 5-di -tert- butyl-4-hydroxyphenyl) propionic acid stearate, 2,5-di -tert- butyl hydroquinone and pentaerythrityl - tetrakis [3- (3,5-di -tert- butyl-4 Hydroxyphenyl)] propionate and other phenolic antioxidants or hydroquinone antioxidants,
2) Bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, tris (2,4-di-tert-butylphenyl) phosphite, tetrakis (2,4-di-tert) -Butyl-5-methylphenyl) 4,4'-biphenylenediphosphonite, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, bis (2,4-di-tert-butylphenyl) Phosphorous secondary antioxidants such as pentaerythritol diphosphite, tris (4-methoxy-3,5-diphenyl) phosphite and tris (nonylphenyl) phosphite, and 3) dilauryl-3,3′-thiodipro Sulfur-based secondary antioxidants such as pionate and 2-mercaptobenzimidazole Rukoto can.

Moreover, a flame retardant can also be mix | blended with the thermoplastic resin which concerns on this invention. A well-known thing can be used as a flame retardant, For example, a halogen flame retardant, an antimony flame retardant, a phosphate ester flame retardant, a metal hydroxide, etc. can be mentioned. Among these, phosphate ester-based flame retardants that are effective with a small amount of blending and can minimize deterioration of water absorption, low dielectric constant, and transparency are preferable, and 1,3-bis (phenylphosphoryl) benzene, 1 , 3-bis (diphenylphosphoryl) benzene, 1,3-bis [di (alkylphenyl) phosphoryl] benzene, 1,3-bis [di (2 ′, 6′-dimethylphenyl) phosphoryl] benzene, 1,3- Bis [di (2 ′, 6′-diethylphenyl) phosphoryl] benzene, 1,3-bis [di (2 ′, 6′-diisopropylphenyl) phosphoryl] benzene, 1,3-bis [di (2 ′, 6) '-Dibutylphenyl) phosphoryl] benzene, 1,3-bis [di (2'-tert-butylphenyl) phosphoryl] benzene, 1,3-bis [di (2'-isopropylphenyl) Phosphoryl] benzene 1,3-bis [di (2′-methylphenyl) phosphoryl] benzene, 1,4-bis (diphenylphosphoryl) benzene,
1,4-bis [di (2 ′, 6′-dimethylphenyl) phosphoryl] benzene, 1,4-bis [di (2 ′, 6′-diethylphenyl) phosphoryl] benzene, 1,4-bis [di ( 2 ′, 6′-diisopropylphenyl) phosphoryl] benzene, 1,4-bis [di (2′-tert-butylphenyl) phosphoryl] benzene, 1,4-bis [di (2′-isopropylphenyl) phosphoryl] benzene , 1,4-bis [di (2'-methyl phenyl) phosphoryl] benzene and 4,4'-bis [di (2 ", 6" - dimethylphenyl) phosphoryl phenyl] condensation type phosphoric ester such as dimethyl methane A flame retardant is more preferable. The blending amount depends on the selected flame retardant and the required degree of flame retardancy, but is preferably 0.5 to 40 parts by weight, more preferably 2 to 30 parts by weight, based on 100 parts by weight of the cyclic olefin polymer. -20 parts by weight is particularly preferred. When the amount of the flame retardant is less than 0.5 parts by weight, the effect is insufficient. On the other hand, when the amount exceeds 40 parts by weight, the transparency is impaired, and the electrical characteristics such as dielectric constant are deteriorated. Or the water absorption increases or the heat resistance deteriorates.

  The thermoplastic resin of the present invention may further include an antioxidant, a heat stabilizer, a light stabilizer, a phase difference adjusting agent, an ultraviolet absorber, an antistatic agent, a dispersant, a processability improver, and a chlorine trap, if necessary. Agent, flame retardant, crystallization nucleating agent, antiblocking agent, antifogging agent, release agent, pigment, organic or inorganic filler, neutralizing agent, lubricant, decomposition agent, metal deactivator, antifouling agent, Known additives such as antibacterial agents, other resins, and thermoplastic elastomers can be added as long as the effects of the invention are not impaired.

<Original film>
The raw film used for the production of the retardation film according to the present invention is formed into a film, a sheet or the like by dissolving and casting a thermoplastic resin, preferably the above-mentioned cyclic olefin resin in an appropriate solvent. can get. It can also be obtained by forming a film by a known method such as a melt extrusion method.

Since the obtained raw film is made of a cyclic olefin resin, it is excellent in balance in optical properties such as transparency, chemical resistance, heat resistance, water resistance and moisture resistance.
The raw film has a film thickness of 100 to 250 μm, preferably 120 to 200 μm, and the difference between the maximum thickness and the minimum thickness of the film is within 3 μm, preferably within 2 μm.

  In addition, a film having an in-plane retardation at a light wavelength of 550 nm of 20 nm or less, preferably 0 to 15 nm, more preferably 0 to 10 nm can be preferably used. Further, the maximum refractive index direction in the film plane is preferably in the range of 0 ± 30 degrees, more preferably in the range of 0 ± 20 degrees with respect to the film longitudinal direction.

<Phase difference film>
The retardation film according to the present invention is a film constituting the polarizing plate of the liquid crystal display element of the present invention, and is made of a thermoplastic resin. The retardation R0 in the film plane is 20 to 150 nm, preferably 30 to 140 nm. Especially preferably, it is 30-130 nm, and NZ coefficient NZ is 1.1-4.3, Preferably it is 1.1-3.9, Most preferably, it is 1.2-3.0. When R0 is less than 20 nm, there is a problem that the optical axis is non-uniform and the in-plane uniformity of the liquid crystal display element is deteriorated, and when it exceeds 150 nm, the viewing angle is narrowed. Further, when NZ is less than 1.1, there is a problem that the viewing angle is narrowed. When NZ is more than 4.3, the optical axis becomes non-uniform, and the in-plane uniformity of the liquid crystal display element is deteriorated. There is.

  In the present invention, the in-plane retardation R0 and the NZ coefficient NZ are nx the maximum refractive index in the film plane at a light wavelength of 550 nm, ny in the direction perpendicular to nx in the film plane, and the film thickness. When the refractive index in the direction is nz and the film thickness is d (nm), the value is obtained by the formula R0 = (nx−ny) × d and the formula NZ = (nx−nz) / (nx−ny). .

  In the retardation film according to the present invention, the maximum refractive index direction may be either the longitudinal direction or the width direction of the film, but is preferably the width direction.

  In addition, the polarizing plate having the retardation film according to the present invention is disposed on the viewer side (front side) and the back side of the liquid crystal display element with the liquid crystal cell interposed therebetween, but the retardation disposed on the viewer side. When R0 of the film is R0f, NZ is NZf, R0 of the retardation film disposed on the back side is R0r, and NZ is NZr, R0f × NZf + R0r × NZr is preferably 200 nm to 260 nm, particularly preferably 220 nm to 240 nm. When the above value is within this range, an effect that a wide viewing angle with a vertical viewing angle of 110 degrees or more and a horizontal viewing angle of 150 degrees or more can be obtained.

  The retardation film described above is also preferably a film roll having a width of 1300 mm or more, more preferably 1500 mm or more, and still more preferably 2000 mm or more. Such a retardation film can be continuously laminated roll-to-roll through a polarizer film roll and, if necessary, an adhesive, to obtain a laminated film. Such a laminated film can be suitably used as a polarizing plate by further laminating a protective film as necessary.

  In addition, it is necessary to use a film roll of a retardation film, a film roll of a polarizer, and a film that can be used as a protective film, preferably a cyclic olefin resin film (raw film) or a film roll of a triacetyl cellulose film. Accordingly, the polarizing plate can be continuously produced by laminating via an adhesive. According to such a method, a polarizing plate can be produced with high production efficiency.

  As will be described later, the retardation film according to the present invention is usually produced by stretching an original film made of a thermoplastic resin, so that the optical properties of the entire film surface can be highly controlled. Specifically, the variation of the in-plane retardation R0 is preferably 2 nm or less, more preferably 1.5 nm or less, and even more preferably 1.0 nm or less. Further, when the angle between the maximum refractive index direction in the film plane and the film width direction is α degrees, α indicating an optical axis deviation is preferably 30 or less, more preferably 25 or less, and still more preferably 20 or less. . As described above, since the optical characteristics are highly controlled, a liquid crystal display element free from display unevenness and free from bright spots can be obtained.

Production Method of Retardation Film The retardation film according to the present invention is the biaxial stretching in which the above-described raw film is (1) uniaxially stretched under heating in the film longitudinal direction and then uniaxially stretched in the film width direction, or (2) It can be suitably manufactured by uniaxially stretching in the film width direction.

  When the raw film is stretched, it is preferable that the heating temperature during stretching is precisely controlled throughout the stretched portion of the film. For example, in the uniaxial stretching in the longitudinal direction in the method (1), that is, longitudinal uniaxial stretching, the temperature distribution is within the set temperature ± 0.6 ° C., preferably within the set temperature ± 0.4 ° C., more preferably the set temperature ± It is desirable to carry out in an oven controlled within 0.2 ° C.

  Here, the set temperature may be equal in all regions in the oven, or may be a temperature in which distribution is provided stepwise or in a gradient manner. When the set temperature is a temperature having a distribution, the actual temperature distribution in the oven and the set temperature distribution are within ± 0.6 ° C., preferably within ± 0.4 ° C., more preferably It is desirable to be within ± 0.2 ° C.

  The set temperature of the uniaxial stretching in the longitudinal direction may be set according to the type of thermoplastic resin constituting the film, the stretching ratio and the stretching speed, the thickness of the film, the desired retardation of the film after stretching, and the like. However, it is usually in the range of (Tg−10 ° C.) to (Tg + 70 ° C.), preferably (Tg ± 0 ° C.), based on the glass transition temperature (Tg) of the thermoplastic resin constituting the raw film. ) To (Tg + 50 ° C.). Such a temperature range is preferable because the film can be stretched without causing thermal degradation and without breaking the film.

When producing the retardation film according to the present invention, the stretching ratio of the uniaxial stretching in the longitudinal direction is, for example, 1.1 to 2.5 times, preferably 1.1 to 2.0 times, and particularly preferably 1.2 to 1. .5 times the range.
Further, the stretching speed of the uniaxial stretching in the longitudinal direction when the retardation film according to the present invention is produced is, for example, in the range of 2 to 100 m / min, preferably 5 to 50 m / min.
When a retardation film is produced by the method (1), the film uniaxially stretched in the longitudinal direction has a film in-plane retardation R0 of usually 100 to 400 nm, preferably 150 to 300 nm.

  The variation of the in-plane retardation R0 in the film uniaxially stretched in the longitudinal direction is usually within ± 3 nm, preferably within ± 2 nm, and more preferably within ± 1 nm. Further, the maximum refractive index direction in the film plane of the film uniaxially stretched in the longitudinal direction is usually in the range of 0 ± 3 degrees, preferably in the range of 0 ± 2 degrees, more preferably 0 ± 1 with respect to the film longitudinal direction. In the range of degrees.

  When the retardation film is produced by the method (1), the film obtained by uniaxially stretching the original film in the longitudinal direction as described above is then uniaxially stretched in the width direction. Moreover, when manufacturing retardation film by the method of said (2), a raw film is uniaxially stretched in the width direction. By carrying out this uniaxial stretching in the width direction, that is, lateral uniaxial stretching under temperature control more precise than uniaxial stretching in the longitudinal direction, a uniform retardation film can be suitably obtained over the entire surface. For example, uniaxial stretching in the width direction is performed in an oven in which the temperature distribution is controlled within a set temperature ± 0.5 ° C, preferably within a set temperature ± 0.3 ° C, more preferably within a set temperature ± 0.2 ° C. It is desirable to do it.

  Here, the set temperature of the uniaxial stretching in the width direction may be the same temperature in the whole region in the oven as in the case of the uniaxial stretching in the longitudinal direction, or a temperature in which the distribution is provided stepwise or in a gradient. Also good. When the set temperature is a temperature having a distribution, the actual temperature distribution in the oven and the set temperature distribution are within ± 0.5 ° C, preferably within ± 0.3 ° C, more preferably It is desirable to be within ± 0.2 ° C. The set temperature in the width direction uniaxial stretching may be the same as or different from the set temperature in the longitudinal direction uniaxial stretching process.

  The set temperature of the uniaxial stretching in the width direction is not particularly limited as in the case of the uniaxial stretching in the longitudinal direction. For example, usually, (Tg-10) on the basis of the glass transition temperature (Tg) of the cyclic olefin resin. ° C) to (Tg + 70 ° C), preferably (Tg ± 0 ° C) to (Tg + 50 ° C).

  The draw ratio of the uniaxial stretching in the width direction may be determined according to the desired characteristics of the optical film to be produced, but in the case of the method (1), for example, 1.2 to 2.5 times, preferably 1. The range is 3 to 2.0 times, particularly preferably 1.4 to 1.7 times. In the case of the method (2), for example, 1.5 to 4 times, preferably 1.7 to 3. It is desirable that the range is 7 times, particularly preferably 2 to 3.5 times.

The stretching speed of the uniaxial stretching in the width direction is, for example, 2 to 100 m / min, preferably 5 to 50 m / min.
When the retardation film is produced by the method (1), the obtained retardation film is, for example, 1.3 to 6.0 times, preferably 1.7 to 3.0 times the original film. It is desirable that the film is stretched at a stretch ratio. This draw ratio is a product of the draw ratio of uniaxial stretching in the longitudinal direction and the draw ratio of uniaxial stretching in the width direction.

  In such a method for producing a retardation film, the type of thermoplastic resin constituting the film, that is, the selection of the resin in consideration of characteristics such as polymer type, copolymerization ratio, molecular weight distribution, glass transition temperature, the longitudinal direction of the film In each step of uniaxial stretching and uniaxial stretching in the width direction, the properties of the obtained retardation film can be controlled by selecting a preset temperature in the oven, selecting a stretching ratio and a stretching speed, and the like.

<Polarizing plate>
The polarizing plate according to the present invention includes the above-described retardation film and a polarizer. Moreover, it has a protective film which protects a polarizer further as needed.

The polarizer constituting the polarizing plate according to a polarizer present invention, can be used without limitation a film having a function as a polarizer, typically a polymer film, adsorbing and orienting iodine or a dichroic dye The polarizer formed by making it use is used. The polarizer constituting the polarizing plate of the present invention is preferably made of a polyvinyl alcohol (PVA) film.

  The polarizer made of a PVA film is not particularly limited as long as it has a function as a polarizer. For example, iodine is adsorbed on a PVA film, and then uniaxially stretched in a boric acid bath. PVA / iodine polarizing film obtained; PVA film obtained by diffusing and adsorbing a direct dye having high dichroism and then uniaxially stretching; PVA film adsorbing iodine and stretching to polyvinylene PVA / polyvinylene polarizing film with structure; PVA / metal polarizing film with gold, silver, mercury, iron, etc. adsorbed on PVA film; PVA film with boric acid solution containing potassium iodide and sodium thiosulfate A near-ultraviolet polarizing film treated with a dichroic dye on the surface and / or inside of a PVA-based film comprising a modified PVA containing a cationic group in the molecule Such as the polarizing film can be given to.

  The method for producing a polarizer comprising a PVA-based film is not particularly limited. For example, a method of adsorbing iodine ions after stretching a PVA-based film; a method of stretching a PVA-based film after dyeing with a dichroic dye A method in which a PVA film is stretched and dyed with a dichroic dye; a method in which a dichroic dye is printed on a PVA film and then stretched; a method in which a PVA film is stretched and then a dichroic dye is printed. Can be mentioned. More specifically, iodine is dissolved in an iodine potassium solution to prepare higher-order iodine ions, the iodine ions are adsorbed on a PVA film and stretched, and then a 1 to 4% boric acid aqueous solution has a bath temperature of 30. A method for producing a polarizing film by immersing at ~ 40 ° C, or treating a PVA film with boric acid in the same manner and stretching it about 3 to 7 times in a uniaxial direction, and bathing in a 0.05 to 5% dichroic dye aqueous solution Examples include a method of producing a polarizing film by immersing at a temperature of 30 to 40 ° C. to adsorb a dye, drying at 80 to 100 ° C., and heat fixing.

  Any of the polarizers according to the present invention preferably has an absorption axis in the longitudinal direction (longitudinal direction). A polarizer having an absorption axis in the longitudinal direction can be produced by stretching a polymer film by longitudinal uniaxial stretching.

Protective film The polarizing plate according to the present invention may have a protective film as necessary in order to maintain the durability and mechanical properties of the polarizer. As the protective film, a film excellent in transparency, water resistance and low moisture absorption can be used, and is not particularly limited. For example, triacetyl cellulose (TAC), cyclic olefin resin, polyethylene terephthalate resin, A film made of polycarbonate resin, acrylic resin, acrylic / styrene copolymer resin, polyolefin resin or the like is preferably used. In the present invention, among these, a film of triacetyl cellulose (TAC) or a cyclic olefin resin can be preferably used. In addition, when using a cyclic olefin-type resin film as a protective film, it is preferable to use the original fabric film mentioned above without extending | stretching.
The polarizing plate according to the present invention is preferably formed by laminating a retardation film, a polarizer, and a protective film in this order.

Adhesive / Adhesive In the present invention, when producing a polarizing plate by adhering a retardation film, a polarizer, and further a protective film as necessary, an adhesive or an adhesive can be used as necessary. . As the pressure-sensitive adhesive or adhesive, any one that does not inhibit the optical properties of the obtained polarizing plate after pressure-sensitive adhesion or adhesion is suitably used.

  As the pressure-sensitive adhesive or adhesive, a water-based adhesive in which polyvinyl alcohol (PVA) is dissolved in water is preferably used. It is also preferable to use a pressure-sensitive adhesive having a polar group or an adhesive having a polar group (hereinafter, these are collectively referred to as “polar group-containing adhesive”).

  Examples of polar groups possessed by the polar group-containing adhesive include halogen atoms and halogen atom-containing groups, carboxyl groups, carbonyl groups, hydroxyl groups, ester groups such as alkyl ester groups and aromatic ester groups, amino groups, amide groups, cyano groups. Group, ether group, acyl group, silyl ether group, thioether group and the like. Among these, a carboxyl group, a carbonyl group, a hydroxyl group, and an ester group are preferable. Moreover, it is preferable that a polar group containing adhesive is an aqueous adhesive or an aqueous adhesive. As a suitable polar group-containing adhesive used for attaching a specific resin film, an aqueous dispersion of an acrylate-based polymer can be exemplified.

The acrylic ester polymer constituting the polar group-containing adhesive can be obtained by polymerizing a monomer composition containing an acrylic ester and a polar group-containing monomer. Examples of the acrylate ester include ethyl acrylate, propyl acrylate, cyclohexyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. The polar group-containing monomer has polar groups such as halogen atoms and halogen atom-containing groups, carboxyl groups, carbonyl groups, hydroxyl groups, ester groups such as alkyl ester groups and aromatic ester groups, amino groups, amide groups, A cyano group, an ether group, an acyl group, a silyl ether group, a thioether group, and the like can be mentioned. Of these, a carboxyl group, a carbonyl group, a hydroxyl group, and an ester group are preferable, and a hydroxyl group and a carboxyl group are particularly preferable. Specific examples of preferable polar group-containing monomers include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylic acid, and methacrylic acid. The ratio of the acrylate ester used for the synthesis of the acrylate ester polymer to the polar group-containing monomer was such that the polar group-containing monomer was 0.1% relative to 100 parts by weight of the acrylate ester polymer. The amount is preferably about 5 to 15 parts by weight.

  Furthermore, it is preferable to use a diene monomer such as divinylbenzene as the monomer used for the synthesis of the acrylate polymer. An acrylic ester polymer obtained by polymerizing a composition containing an acrylic ester, a polar group-containing monomer, and a diene monomer can form a high-strength adhesive layer. Here, the amount of the diene monomer used is desirably 0 to 10 parts by weight with respect to 100 parts by weight of the acrylate polymer. When the usage-amount of a diene monomer exceeds 10 weight part, an adhesive layer or an adhesive bond layer will become hard.

  Examples of the polymerization method for obtaining the acrylic ester polymer include an emulsion polymerization method, a suspension polymerization method, and a solution polymerization method. If a nonpolar solvent such as toluene or xylene is used as the polymerization solvent, it is not preferable because, when the resulting pressure-sensitive adhesive is used, a deviation or the like tends to occur between the polarizer to be bonded and the optical film. .

  As the molecular weight of the acrylate ester-based polymer constituting the polar group-containing adhesive, the number average molecular weight (Mn) in terms of polystyrene measured by GPC analysis is preferably 5,000 to 500,000. The molecular weight distribution is preferably 10,000 to 200,000, and the weight average molecular weight (Mw) is preferably 15,000 to 1,000,000, more preferably 20,000 to 500,000. (Mw / Mn) is preferably 1.2 to 5, and more preferably 1.4 to 3.6.

  To the polar group-containing adhesive that can be used in the present invention, a crosslinking agent such as isocyanate and butylated melamine, an ultraviolet absorber, and the like can be added. Here, the addition of the crosslinking agent to the polar group-containing adhesive is usually performed immediately before the polar group-containing adhesive is applied.

Manufacturing method of polarizing plate The polarizing plate according to the present invention is preferably manufactured by laminating a retardation film on one surface of a polarizer made of a PVA film or the like using an adhesive or an adhesive, and heating and pressing it. can do. More preferably, it can be produced by laminating a phase difference on one surface of the polarizer and a protective film on the opposite surface of the polarizer using an adhesive or an adhesive, respectively, and heating and pressure-bonding them. .

  In the production of the polarizing plate, both are bonded so that the maximum refractive index direction in the film plane of the retardation film and the absorption axis of the polarizer are orthogonal.

<Liquid crystal display element>
The liquid crystal display element of the present invention has the polarizing plate described above, and is usually a TN mode liquid crystal display element having a structure in which a liquid crystal cell is sandwiched between two polarizing plates. The TN mode liquid crystal display element is a display element having a liquid crystal cell using a TN type liquid crystal.
For example, when the liquid crystal display element of the present invention has two polarizing films laminated in this order, a retardation film, a polarizer, and a protective film, both surfaces of the liquid crystal cell are respectively connected to the retardation film side surface of the polarizing plate. A bonded structure is preferably employed. For the adhesion between the liquid crystal cell and each polarizing plate, the above-mentioned pressure-sensitive adhesive or adhesive that can be used for production of the polarizing plate can be used. Further, a pressure-sensitive adhesive layer may be further provided on the surface of each polarizing plate to be bonded to the liquid crystal cell in advance, thereby bonding the polarizing plate and the liquid crystal cell.

  The liquid crystal display element according to the present invention has a highly controlled optical performance over the entire surface, and the entire surface is uniform even with a wide panel. Therefore, the liquid crystal display element is particularly used for a TN mode liquid crystal monitor equipped with a large display. Can be suitably used.

  The liquid crystal display element of the present invention is provided with the polarizing plate described above, so that the display performance is excellent, and the viewing angle is preferably 110 ° or more, and more preferably 120 ° or more.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. Each property was measured or evaluated as follows.
(1) Measuring method of R0 and maximum refractive index direction The phase difference R0 and NZ in the film surface of an optical film were measured using "KOBRA-21ADH" by Oji Scientific Instruments.
(2) The NZ coefficient of the NZ coefficient optical film (retardation film) is measured by “KOBRA-21ADH” manufactured by Oji Scientific Instruments Co., Ltd. The refractive index nx in the X axis direction of the optical film, and in the Y axis direction It calculated | required by the following formula from refractive index ny and refractive index nz of the Z-axis direction.
NZ = (nx-nz) / (nx-ny)
(2) Polarization degree of polarizing plate Using V-7300 manufactured by JASCO Corporation, the polarization degree of the polarizing plate was measured by making it incident from the adhesive / adhesive side of the optical film.
(3) Contrast ratio measurement of liquid crystal display element Using “EZ contrast-XL88” manufactured by ELDIM Co., Ltd., the luminance, viewing angle, and contrast ratio of the liquid crystal display element were measured in a dark room with an illuminance of 1 lx or less.

(4) Glass transition temperature (Tg )
Using a DSC6200 manufactured by Seiko Instruments Inc., the temperature increase rate was measured at 20 ° C. per minute under a nitrogen stream. Tg is the tangent on the baseline starting from point B, with the differential peak scanning calorie maximum peak temperature (point A) and the temperature at −20 ° C. from the maximum peak temperature (point B) plotted on the differential scanning calorimetry curve. And the intersection of the tangent starting from point A.
(5) Hydrogenation rate As a nuclear magnetic resonance spectrometer (NMR), AVANCE 500 manufactured by Bruker was used, and ¹ H-NMR was measured using d-chloroform as a measurement solvent. The hydrogenation rate was calculated after calculating the monomer composition from the integral value of 5.1 to 5.8 ppm of vinylene group, 3.7 ppm of methoxy group, and 0.6 to 2.8 ppm of aliphatic proton.
(6) Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)
Gel permeation chromatography (Tosoh Co., Ltd. HLC-8220GPC, column: Tosoh Co., Ltd. guard column H _XL- H, TSK gel G7000H _XL , TSKgel GMH _XL , TSK gel G2000H _XL , sequentially connected, solvent: Tetrahydrofuran, flow rate: 1 mL / min, sample concentration: 0.7 to 0.8% by weight, injection amount: 70 μL, measurement temperature: 40 ° C., detector: RI (40 ° C.), standard material: manufactured by Tosoh Corporation Using TSK standard polystyrene), the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) were measured. The Mn is a number average molecular weight.

(7) Residual solvent amount A sample was dissolved in methylene chloride, and the resulting solution was analyzed using gas chromatography (Shimadzu GC-7A).
(8) Logarithmic viscosity Using a Ubbelohde viscometer, the viscosity was measured in chloroform (sample concentration: 0.5 g / dL) at 30 ° C.
(9) Saturated water absorption Based on ASTM D570, the sample was immersed in water at 23 ° C. for 1 week, and the change in weight before and after immersion was measured.

(10) total light transmittance was measured using a haze manufactured by Suga Test Instruments Co., Ltd. haze meter (HGM-2DP type).
(11) <Wet heat test>
After a polarizing plate having an adhesive layer was bonded to the glass for LCD, it was stored for 500 hours in an environment at a temperature of 85 ° C. and a relative humidity of 85%, and then the degree of polarization was measured. The degree of polarization was evaluated according to the following standard (1) from the value of the amount of change in the degree of polarization before and after the durability test represented by the following formula.
(12) <Dry heat test>
After pasting the polarizing plate having the adhesive layer on the glass for LCD, it was stored for 500 hours in an environment at a temperature of 95 ° C., and then the degree of polarization was measured. The degree of polarization was evaluated according to the following criteria from the amount of change in the degree of polarization before and after the durability test represented by the following formula.
<Standard>
A: Change in polarization degree is less than 0.5% B: Change in polarization degree is 0.5% or more and less than 2.0% X: Change in polarization degree is 2.0% or more [Change in polarization degree ] = (1− [degree of polarization after test] / [initial degree of polarization]) × 100 (%)

[Synthesis Example 1] (Production of Cyclic Olefin Resin A)
8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10] -3-dodecene (DNM) and 225 parts of bicyclo [2.2.1] hept-2 using ene (NB) and 25 parts of a monomer, 1-hexene (molecular weight modifier) Together with 27 parts and 750 parts of toluene (solvent for ring-opening polymerization reaction), the reaction vessel was purged with nitrogen, and this solution was heated to 60 ° C. Next, in the solution in the reaction vessel, as a polymerization catalyst, 0.62 part of a toluene solution of triethylaluminum (1.5 mol / liter), tungsten hexachloride modified with tert-butanol and methanol (tert-butanol: methanol: tungsten) = 0.35 mol: 0.3 mol: adding a toluene solution (concentration 0.05 mol / l) 3.7 parts of 1 mol), by ring-opening polymerization reaction by heating for 3 hours and stirred at the solution 80 ° C. the A ring-opening polymer solution was obtained. The polymerization conversion rate in this polymerization reaction was 97%.
Charged this way the ring-opening polymer solution of 1,000 parts of the obtained in the autoclave, this ring-opening polymer solution, RuHCl (CO) [P ( C 6 H 5) 3] 3 and 0.12 part of additive Then, the hydrogenation reaction was performed by heating and stirring for 3 hours under the conditions of a hydrogen gas pressure of 100 kg / cm ² and a reaction temperature of 165 ° C.
After cooling the obtained reaction solution (hydrogenated polymer solution), the hydrogen gas was released. This reaction solution was poured into a large amount of methanol to separate and recover a coagulated product, which was dried to obtain a hydrogenated polymer (hereinafter referred to as “resin A”).
The hydrogenation rate measured by ¹ H-NMR of the resin A thus obtained was 99.9%, the Tg measured by the DSC method was 130 ° C., the Mn in terms of polystyrene measured by the GPC method was 20,800, Mw was 62,000, Mw / Mn was 3.00, saturated water absorption at 23 ° C. was 0.21%, and logarithmic viscosity in chloroform at 30 ° C. was 0.51 dl / g.

[Synthesis Example 2] (Production of Cyclic Olefin Resin B)
Using 71 parts of DNM, 15 parts of dicyclopentadiene (DCP) and 1 part of NB as monomers, together with 18 parts of molecular weight regulator 1-hexene and 200 parts of toluene, charged in a nitrogen-substituted reaction vessel and brought to 100 ° C. Heated.
To this, 0.005 part of triethylaluminum and 0.005 part of methanol-modified WCl ₆ (anhydrous methanol: PhPOCl ₂ : WCl ₆ = 103: 630: 427 weight ratio) were added and reacted for 1 minute, and then 10 parts of DCP and NB3 A copolymer of DNM / DCP / NB = 69.77 / 26.01 / 4.23 (wt%) was obtained by further adding a portion in 5 minutes and further reacting for 45 minutes.
Next, the obtained copolymer solution was placed in an autoclave, and 200 parts of toluene was further added. Next, 1 part of octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate as a reaction modifier and RuHCl (CO) [P (C ₆ H ₅ )] as a hydrogenation catalyst _After adding 0.006 part of ₃ and heating to 155 ° C., hydrogen gas was charged into the reactor, and the pressure was adjusted to 10 MPa. Thereafter, the reaction was carried out at 165 ° C. for 3 hours while maintaining the pressure at 10 MPa. After completion of the reaction, 100 parts by weight of toluene, 3 parts by weight of distilled water, 0.72 parts by weight of lactic acid and 0.00214 parts by weight of hydrogen peroxide were added and heated at 60 ° C. for 30 minutes. Thereafter, 200 parts by weight of methanol was added and heated at 60 ° C. for 30 minutes, and when cooled to 25 ° C., it was separated into two layers. Remove 500 parts by weight of the supernatant, add 350 parts by weight of toluene and 3 parts by weight of water again, heat at 60 ° C. for 30 minutes, then add 240 parts by weight of methanol, heat at 60 ° C. for 30 minutes, and cool to 25 ° C. Separated into two layers. Remove 500 parts by weight of the supernatant, add 350 parts by weight of toluene and 3 parts by weight of water, heat at 60 ° C. for 30 minutes, then add 240 parts by weight of methanol, heat at 60 ° C. for 30 minutes, and cool to 25 ° C. Separated into two layers. Finally, after removing 500 parts by weight of the supernatant, the remaining polymer solution was filtered using 2.0 μm, 1.0 μm, and 0.2 μm filters. Thereafter, the solid content of the polymer was concentrated to 55%, the solvent was removed at 250 ° C., 4 torr, and a residence time of 1 hour, and the polymer was passed through a 10 μm polymer filter to obtain a copolymer (hereinafter “resin B”). That said.)
The hydrogenation rate measured by ¹ H-NMR of the resin B thus obtained was 99.9%, Tg measured by DSC method was 131 ° C., Mn in terms of polystyrene measured by GPC method was 16,000, The Mw was 61,000 and the Mw / Mn was 3.81, the saturated water absorption at 23 ° C. was 0.18%, and the logarithmic viscosity in chloroform at 30 ° C. was 0.52 dl / g.

[Synthesis Example 3] (Production of Cyclic Olefin Resin C)
Obtained in Synthesis Example 1, 250 parts of amount of DNM, except that the 18 parts of the addition amount of 1-hexene, in the same manner as in Synthesis Example 1 hydrogenated polymer (hereinafter referred to as "Resin C".) The It was.
The hydrogenation rate measured by 1H-NMR of the resin C thus obtained was 99.9%, the Tg measured by the DSC method was 165 ° C., the Mn in terms of polystyrene measured by the GPC method was 32,000, Mw Was 137,000 and Mw / Mn was 4.29, the saturated water absorption at 23 ° C. was 0.3%, and the logarithmic viscosity in chloroform at 30 ° C. was 0.78 dl / g.

[Preparation Example] (Preparation of aqueous adhesive)
G of distilled water 250 parts to the reaction vessel, and 90 parts of butyl acrylate to the reaction vessel, and 8 parts of 2-hydroxyethyl methacrylate, and 2 parts of divinyl benzene, were added 0.1 part of potassium oleate, this The dispersion treatment was performed by stirring with a stirring blade made of Teflon (registered trademark).
After replacing the inside of the reaction vessel with nitrogen, the temperature of the system was raised to 50 ° C., and 0.2 part of potassium persulfate was added to initiate polymerization. After 2 hours, 0.1 part of potassium persulfate was further added, the system was heated to 80 ° C., and the polymerization reaction was continued for 1 hour to obtain a polymer dispersion.
Next, by using an evaporator, the polymer dispersion is concentrated until the solid content concentration becomes 70%, whereby an aqueous adhesive (adhesive having a polar group) composed of an aqueous dispersion of an acrylic ester polymer. Got.
The acrylic ester polymer constituting the water-based pressure-sensitive adhesive thus obtained was measured for polystyrene-reduced number average molecular weight (Mn) and weight average molecular weight (Mw) by the GPC method (solvent: tetrahydrofuran). Mn was 69,000, Mw was 135,000, and the logarithmic viscosity measured in chloroform at 30 ° C. was 1.2 dl / g.

[Production Example 1] (Production of raw film A)
Resin A obtained in Synthesis Example 1 is dissolved in toluene so as to have a concentration of 30% (solution viscosity at room temperature is 30,000 mPa · s), and pentaerythrityl tetrakis [3- (3,5 -Di-tert-butyl-4-hydroxyphenyl) propionate] was added in an amount of 0.1 part by weight to 100 parts by weight of the resin, and a metal fiber sintered filter having a pore diameter of 5 μm manufactured by Nippon Pole was used. Filtration was performed while controlling the flow rate of the solution so that it was within 4 MPa.
The resin solution produced by the above method is extruded downstream using a gear pump using a twin screw extruder (manufactured by Toshiba Machine Co., Ltd .; TEM-48) while degassing toluene with a three-stage vent. The resin flown out of the strand die was cooled in a cooling water tank, then sent to a strand cutter, and cut into rice grains to obtain a granulated resin.
This granulated resin was dried at 100 ° C. for 4 hours in a nitrogen atmosphere, then sent to a single-screw extruder (90 mmΦ), and melted at 260 ° C., and quantitative extrusion was performed with a gear pump, with a nominal opening of 10 μm. Using a metal fiber sintered filter manufactured by Nippon Seisen Co., Ltd., melt filtration is performed, and a coat hanger die (1700 mm width) is used to form a film at 260 ° C. with a gap at the coat hanger die outlet of 0.5 mm. Extruded. The die land length (the length of the parallel part of the die exit) of the die used at this time was 20 mm. The distance from the die exit to the roll crimping point is set to 65 mm, and the extruded film is sandwiched between a 250 mmφ mirror surface roll with a surface roughness of 0.1 S and a metal belt with a thickness of 0.3 mm to gloss the film surface. Transferred to the surface. The metal belt (width 1650 mm) is held by a rubber-coated roll (the diameter of the roll to be held is 150 mmΦ) and a cooling roll (roll diameter 150 mm), and a commercially available sleeve type transfer roll (manufactured by Chiba Machine Industry) is used. And transcribed. The roll interval during transfer was 0.35 mm, and the transfer pressure was 0.35 MPa.
The peripheral speed of the outer periphery of the mirror surface roll at this time was 10 m / min. At this time, the temperature of the mirror surface roll was set to 125 ° C. using an oil temperature controller, and the temperature of the rubber coating roll was set to 115 ° C.
On the downstream side of the mirror roll, a cooling roll having a diameter of 250 mm was arranged, and the film peeled off from the mirror roll was cooled for 2.1 seconds until it was pressure-bonded to the cooling roll set at 115 ° C. Thereafter, the film was peeled off at a peel tension of 0.4 MPa · cm, a masking film was bonded to one side, and the film was wound up by a winder to obtain a resin film having a thickness of 130 μm (hereinafter referred to as “raw film A”). Called). The residual solvent amount of the obtained film was 0.1%, the total light transmittance was 93%, and the glass transition temperature (Tg) was 130 ° C.

[Production Example 2] (Production of raw film B)
In Production Example 1, a resin film having a thickness of 130 μm was obtained in the same manner as in Production Example 1 except that Resin B obtained in Synthesis Example 2 was used instead of Resin A (hereinafter referred to as “raw film B”). "). The film obtained had a residual solvent amount of 0.1%, a total light transmittance of 93%, and a glass transition temperature (Tg) of 131 ° C.

[Production Example 3] (Production of raw film C)
The resin C obtained in Synthesis Example 3 30% concentration in toluene (solution viscosity at room temperature 30,000 mPa · s) were dissolved so as to, pentaerythrityl tetrakis as an antioxidant [3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate] is added in an amount of 0.1 part by weight to 100 parts by weight of the polymer, and a metal fiber sintered filter made by Nippon Pole with a pore diameter of 5 μm is used. Filtration was performed while controlling the flow rate of the solution so that it was within 0.4 MPa. The obtained polymer solution was treated with an acrylic acid-based INVEX lab coater installed in a Class 1000 clean room and made hydrophilic with an acrylic acid (surface-adhesive) surface-treated PET film having a thickness of 100 μm (Toray Industries, Inc.) The film thickness after drying was applied to 130 μm on Lumirror U94 (manufactured by Co., Ltd.), this was first dried at 50 ° C., then peeled off from the PET film and secondarily dried at 90 ° C. to obtain a resin film (Hereinafter referred to as “film C”). The amount of residual solvent of the obtained film C was 0.1%, the total light transmittance was 93%, and the glass transition temperature (Tg) was 165 ° C.

[Production Example 4] (Production of protective film)
Using a twin screw extruder, 0.3 parts of (pentaerythrityltetrakis-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate: melting point 115 ° C.) with respect to 100 parts of resin A, benzo As a triazole compound, (2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol]: melting point 199 ° C.) 1.5 After being melt-kneaded at a blending ratio of 270 ° C. at a part ratio, it was extruded onto a strand, cooled with water, and then pellets were obtained through a feeder ruder. The obtained pellets were circulated and dehumidified and dried at 100 ° C. for 3 hours under nitrogen, then sent to a hopper and melted at a resin temperature of 270 ° C. using a single screw extruder having a screw diameter of 75 mmφ.
This molten resin was guided to a 700 mm wide coat hanger die through a polymer filter (aperture 5 μm) heated to 280 ° C. at a rate of 30 kg / hr by a double shaft discharge type gear pump. The differential pressure between the inlet and outlet of the filter was 3 MPa. Further, the heater of the die set at 250 ° C. using an aluminum cast heater, a lip heater is installed in addition to the lip of the front, was controlled die lip temperature of 250 ± 0.4 ° C..
The lip opening was set to 0.5 mm in the width direction, and fine adjustment was performed by measuring thickness unevenness with an on-line thickness gauge installed on the downstream side of melt extrusion. The resin coming out of the die was dropped in the lead direct wire direction of a 250 mmφ cast roll (surface roughness: 0.1 μm) and crimped, and then pressed in order with two cooling rolls installed horizontally to the cast roll axis, and then peeled off. The tension was controlled at 4 kgf and the film was taken out to obtain a protective film α having a thickness of 80 μm.

[Production Example 5] (Production of polarizer)
A 120 μm roll polyvinyl alcohol (hereinafter also referred to as “PVA”) film made of a 30 ° C. aqueous dye bath having an iodine concentration of 0.03% by weight and a potassium iodide concentration of 0.5% by weight. In a 55 ° C. cross-linking bath of an aqueous solution having a boric acid concentration of 5% by weight and a potassium iodide concentration of 8% by weight after being continuously uniaxially stretched (pre-stretched) at a stretch ratio of 3 times Then, the film was further uniaxially stretched (post-stretched) in the longitudinal direction at a stretch ratio of 2 times, dried and wound up to obtain a 27 μm roll-shaped polarizer.

[Example 1]
Using the raw film A obtained in Production Example 1, in a tank at a stretching machine furnace temperature of 136 ° C., a stretching speed of 5 m / min, a stretching ratio of 1.4 times, and a film longitudinal direction that does not fix the film width direction After uniaxial stretching, in a tank at a temperature of 150 ° C. in a stretching machine furnace, tenter transverse stretching is performed at a stretching speed of 5.0 m / min and a stretching ratio of 1.7 times, and a roll-like retardation film having a thickness of 69 μm A was obtained. The in-plane retardation R0 of the obtained retardation film A was 40.1 nm, and the NZ coefficient was 2.9.
In the obtained retardation film A, the roll film is aligned on one side of the polarizer obtained in Production Example 5 (the stretching direction which is the absorption axis of the polarizer and the maximum refractive index direction of the retardation film A). The protective film α obtained in Production Example 4 was obtained in Preparation Example on the other surface of the polarizer using the aqueous adhesive obtained in Preparation Example. It stuck using the water-system adhesive agent, and polarizing plate A-1 was obtained. When the single transmittance and degree of polarization of the obtained polarizing plate were examined, they were 42.1% and 99.9%, respectively. Further, the obtained polarizing plate A-1 was subjected to a wet heat test and a dry heat test, respectively. The results are shown in Table 1.

The polarizing plate on the viewer side and the back side of the TN mode liquid crystal display element of a liquid crystal television (model code: LS20BRDBBV / XSJ) manufactured by Samsung Electronics Co., Ltd. is peeled off, and the polarizing plate A-1 is placed on both sides of the peeled portion. The polarizing plate was attached so that the retardation film surface of the polarizing plate was on the liquid crystal cell side in the same manner as the transmission axis of the polarizing plate originally attached.
When the viewing angle (region having a contrast ratio of 10 or more) was confirmed in all directions of the obtained TN mode liquid crystal display element, it was confirmed to be 125 degrees up and down and 160 degrees left and right. Further, when the presence or absence of bright spots during black display was confirmed, the number was 1 on the entire panel. The results are shown in Table 1.

[Example 2]
Using the raw film A obtained in Production Example 1, tenter transverse stretching was performed at a stretching speed of 5 m / min and a stretching ratio of 3.0 in a tank at a temperature of 145 ° C. in a stretching machine, and a roll having a thickness of 43 μm A phase difference film B was obtained. The in-plane retardation R0 of the obtained retardation film B was 90.2 nm, and the NZ coefficient was 1.3.
A polarizing plate B-1 was obtained in the same manner as in Example 1 except that the retardation film B was used instead of the retardation film A in Example 1. When the single transmittance and degree of polarization of the obtained polarizing plate were examined, they were 42.0% and 99.9%, respectively. Moreover, when the wet heat test and the dry heat test were conducted in the same manner as in Example 1, they were evaluated as ◎.
When a TN mode liquid crystal display element was obtained and evaluated in the same manner as in Example 1, the viewing angle was 123 degrees in the vertical direction and 160 degrees in the horizontal direction, and the presence or absence of bright spots was confirmed. . The results are also shown in Table 1.

[Example 3]
Using the raw film B obtained in Production Example 2, in a tank at a stretching machine furnace temperature of 138 ° C., with a stretching speed of 5 m / min and a stretching ratio of 1.4 times, the film width direction is not fixed. After the uniaxial stretching, a tenter transverse stretching was performed at a stretching speed of 5 m / min and a stretching ratio of 1.7 times in a tank having a temperature in a stretching machine furnace of 152 ° C. Obtained. The in-plane retardation R0 of the obtained retardation film C was 40.0 nm, and the NZ coefficient was 2.9.
In Example 1, a polarizing plate C-1 was obtained in the same manner as in Example 1 except that the retardation film C was used instead of the retardation film A. When the single transmittance and degree of polarization of the obtained polarizing plate were examined, they were 42.0% and 99.9%, respectively. Moreover, when the wet heat test and the dry heat test were conducted in the same manner as in Example 1, they were evaluated as ◎.
When a TN mode liquid crystal display element was obtained and evaluated in the same manner as in Example 1, the viewing angle was 123 degrees up and down and 158 degrees left and right, and the presence or absence of bright spots was confirmed. . The results are also shown in Table 1.

[Example 4]
Using the raw film C obtained in Production Example 3, in a tank at a stretching machine furnace temperature of 169 ° C., a stretching speed of 5 m / min, a stretching ratio of 1.4 times, and a film longitudinal direction that does not fix the film width direction After uniaxial stretching, a tenter transverse stretching was performed at a stretching speed of 5 m / min and a stretching ratio of 1.7 times in a tank at a temperature of 183 ° C. in a stretching machine, and a roll-like retardation film D having a thickness of 73 μm was obtained. Obtained. The in-plane retardation R0 of the obtained retardation film D was 40.4 nm, and the NZ coefficient was 2.9.
A polarizing plate D-1 was obtained in the same manner as in Example 1 except that the retardation film D was used instead of the retardation film A in Example 1. When the single transmittance and degree of polarization of the obtained polarizing plate were examined, they were 42.1% and 99.9%, respectively. Moreover, when the wet heat test and the dry heat test were conducted in the same manner as in Example 1, they were evaluated as ◎.
When a TN mode liquid crystal display device was obtained and evaluated in the same manner as in Example 1, the viewing angle was 122 degrees up and down and 153 degrees on the left and right. It was. The results are also shown in Table 1.

[Example 5]
In Example 1, a polarizing plate A-2 was obtained in the same manner as in Example 1 except that a film made of triacetyl cellulose (hereinafter also referred to as “TAC”) was used instead of the protective film α. When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 41.6% and 99.9%, respectively. Further, the wet heat test and the dry heat test were conducted in the same manner as in Example 1, and the results were ◎ and ◯, respectively.
When a TN mode liquid crystal display element was obtained and evaluated in the same manner as in Example 1, the viewing angle was 119 degrees up and down, and 159 degrees left and right. It was. The results are also shown in Table 1.

[Example 6]
In Example 2, a polarizing plate B-2 was obtained in the same manner as in Example 2 except that a TAC film was used instead of the protective film α. When the single transmittance and degree of polarization of the obtained polarizing plate were examined, they were 41.7% and 99.9%, respectively. Further, the wet heat test and the dry heat test were conducted in the same manner as in Example 1, and the results were ◎ and ◯, respectively.
When a TN mode liquid crystal display element was obtained and evaluated in the same manner as in Example 1, the viewing angle was 118 degrees up and down, and 159 degrees left and right. It was. The results are also shown in Table 1.

[Example 7]
In Example 3, a polarizing plate C-2 was obtained in the same manner as in Example 3 except that a TAC film was used instead of the protective film α. When the single transmittance and degree of polarization of the obtained polarizing plate were examined, they were 41.5% and 99.9%, respectively. Further, the wet heat test and the dry heat test were conducted in the same manner as in Example 1, and the results were ◎ and ◯, respectively.
When a TN mode liquid crystal display device was obtained and evaluated in the same manner as in Example 1, the viewing angle was 116 degrees up and down and 155 degrees on the left and right. It was. The results are also shown in Table 1.

[Example 8]
In Example 4, a polarizing plate D-2 was obtained in the same manner as in Example 4 except that a TAC film was used instead of the protective film α. When the single transmittance and the degree of polarization of the obtained polarizing plate were examined, they were 41.4% and 99.9%, respectively. Further, the wet heat test and the dry heat test were conducted in the same manner as in Example 1, and the results were ◎ and ◯, respectively.
When a TN mode liquid crystal display element was obtained and evaluated in the same manner as in Example 1, the viewing angle was 114 degrees up and down and 154 degrees on the left and right, and the presence or absence of bright spots was confirmed. It was. The results are also shown in Table 1.

[Example 9]
Cellulose-based resin unstretched film having a ratio of acetyl substitution degree / propionyl substitution degree of 70/30 is stretched at a stretching speed of 5 m / min and a stretching ratio of 1.6 times in a tank at a stretching machine furnace temperature of 138 ° C. After uniaxial stretching in the longitudinal direction of the film without fixing the film width direction, tenter transverse stretching is performed at a stretching speed of 5 m / min and a stretching ratio of 1.9 times in a tank having a temperature in a stretching machine furnace of 152 ° C. A 52 μm roll-shaped retardation film E was obtained. The in-plane retardation R0 of the obtained retardation film E was 40.5 nm, and the NZ coefficient was 2.9.
In Example 1, a polarizing plate E-1 was obtained in the same manner as in Example 1 except that the retardation film E was used instead of the retardation film A. When the single transmittance and degree of polarization of the obtained polarizing plate were examined, they were 41.3% and 99.9%, respectively. Further, the wet heat test and the dry heat test were conducted in the same manner as in Example 1, and the results were ◎ and ◯, respectively.
It was evaluated to obtain a TN mode liquid crystal display device in the same manner as in Example 1, the viewing angle vertically 113 degrees, a right 152 degrees, was to confirm the presence or absence of bright spots, a four panel entirely It was. The results are also shown in Table 1.

[Comparative Example 1]
Using the raw film A obtained in Production Example 1, a roll having a thickness of 65 μm is subjected to tenter transverse stretching at a stretching speed of 5 m / min and a stretching ratio of 2.3 times in a tank having a temperature in a stretching machine furnace of 135 ° C. A phase difference film F was obtained. The in-plane retardation R0 of the obtained retardation film F was 180.4 nm, and the NZ coefficient was 1.4.
In Example 1, polarizing plate F-1 was obtained in the same manner as in Example 1 except that the retardation film F was used instead of the retardation film A. When the single transmittance and degree of polarization of the obtained polarizing plate were examined, they were 42.1% and 99.9%, respectively. Moreover, when the wet heat test and the dry heat test were conducted in the same manner as in Example 1, they were evaluated as ◎.
When a TN mode liquid crystal display element was obtained and evaluated in the same manner as in Example 1, the viewing angle was 40 degrees up and down and 159 degrees left and right, and the viewing angle in the up and down direction was very narrow. When the presence or absence of a bright spot was confirmed, it was 1 on the entire panel surface. The results are also shown in Table 1.

[Comparative Example 2]
Using the raw film A obtained in Production Example 1, in a tank at a stretching machine furnace temperature of 133 ° C., a stretching speed of 5 m / min, a stretching ratio of 1.6 times, and a film longitudinal direction that does not fix the film width direction After uniaxial stretching, a tenter transverse stretching is performed at a stretching speed of 5.0 m / min and a stretching ratio of 1.9 times in a tank having a temperature in a stretching machine furnace of 146 ° C., and a roll retardation film having a thickness of 56 μm. G was obtained. The in-plane retardation R0 of the obtained retardation film A was 40.1 nm, and the NZ coefficient was 5.3. A polarizing plate G-2 was obtained in the same manner as in Example 5 except that the retardation film G was used instead of the retardation film A in Example 5. When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 41.9% and 99.9%, respectively. Moreover, when the wet heat test and the dry heat test were conducted in the same manner as in Example 5, they were A and B, respectively.
When a TN mode liquid crystal display element was obtained and evaluated in the same manner as in Example 5, the viewing angle was 43 degrees up and down and 155 degrees left and right, and the viewing angle in the up and down direction was very narrow. Moreover, when the presence or absence of a bright spot was confirmed, it was three on the whole panel surface. The results are also shown in Table 1.

[Comparative Example 3]
An alignment film composed of a modified PVA having a vinyl-based repeating unit having a bonding group in the side chain is formed on a triacetyl cellulose film having a thickness of 80 μm, and a discotic liquid crystal having a polymerizable group bonded to the alignment film. A composition having a compound and a photopolymerization initiator was applied and heated, and then irradiated with ultraviolet rays to obtain a retardation film H. The in-plane retardation R0 of the obtained retardation film H was 40.5 nm, and the NZ coefficient was 4.56. A polarizing plate H-2 was obtained in the same manner as in Example 5 except that the retardation film H was used instead of the retardation film A in Example 5. When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 40.9% and 99.9%, respectively. Moreover, when the wet heat test and the dry heat test were conducted in the same manner as in Example 5, they were A and X, respectively.
When a TN mode liquid crystal display element was obtained and evaluated in the same manner as in Example 5, the viewing angles were 120 degrees up and down and 146 degrees left and right. The presence or absence of bright spots on the entire panel was confirmed to be 15. The results are also shown in Table 1.

Claims (6)

Two polarizing plates having a polarizer and a retardation film composed of a thermoplastic resin, sandwiching a liquid crystal cell is disposed on the rear side and the viewer side of the liquid crystal display element to form the respective polarizers The retardation film satisfies the following formulas (i), (ii) and (iii), and
A TN mode liquid crystal display element, wherein each polarizing plate is bonded to each other so that the maximum refractive index direction in the film plane of the retardation film and the absorption axis of the polarizer are orthogonal to each other .
(I) 20 nm ≦ R0 ≦ 150 nm
(Ii) 1.1 ≦ NZ ≦ 4.3
(Iii) 200 nm ≦ R0f × NZf + R0r × NZr ≦ 260 nm
(Where R0 represents the retardation in the film plane, NZ represents the NZ coefficient, nx represents the maximum refractive index in the film plane at a light wavelength of 550 nm, and the refractive index in the direction perpendicular to nx in the film plane) Is ny, the refractive index in the film thickness direction is nz, and the thickness is d (nm), and is calculated by the formula R0 = (nx−ny) × d and the formula NZ = (nx−nz) / (nx−ny). R0f and NZf respectively represent R0 and NZ of the optical film on the viewer side of the liquid crystal display element, and R0r and NZr respectively represent R0 and NZ of the optical film on the back side of the liquid crystal display element. The TN mode liquid crystal display element according to claim 1, wherein the retardation film satisfies the following formulas (iv) and (v).
(Iv) 70 nm ≦ R0 ≦ 150 nm
(V) 1.1 ≦ NZ ≦ 1.5 The TN mode liquid crystal display element according to claim 1 or 2 , wherein the thermoplastic resin constituting the retardation film is a cyclic olefin resin having a repeating unit represented by the following formula (I).

[In the formula (I), m is an integer of 1 or more, p is 0 or an integer of 1 or more, D is a group represented by —CH═CH— or —CH ₂ CH ₂ —, R ^{1 to} R ⁴ are each independently a hydrogen atom; a halogen atom; a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms; a polar group R ¹ and R ² may be combined to form a divalent hydrocarbon group, and R ³ and R ⁴ may be combined to form a divalent hydrocarbon group. May be. R ¹ and R ² may be bonded to each other to form a carbocyclic or heterocyclic ring, and R ³ and R ⁴ may be bonded to each other to form a carbocyclic or heterocyclic ring. May be monocyclic or polycyclic. ] Furthermore, a polarizing plate has a protective film, The TN mode liquid crystal display element in any one of Claims 1-3 characterized by the above-mentioned. The TN mode liquid crystal according to any one of claims 1 to 4, wherein the retardation film constituting the polarizing plate is obtained by stretching an original film made of a thermoplastic resin. Display element. A step of creating a retardation film satisfying the above formulas (i) and (ii) by stretching an original film made of a thermoplastic resin, and a polarizing plate is produced by superimposing the retardation film and a polarizer. The TN mode liquid crystal display element according to claim 1, wherein the TN mode liquid crystal display element is obtained by a manufacturing method comprising a step of superposing the obtained polarizing plate on a liquid crystal cell .