JP2008003424A - Polarizing plate and liquid crystal display device - Google Patents

Abstract

Disclosed is a polarizing plate suitable for a liquid crystal display device and the like, which is free of visual defects due to interference of light such as interference fringes, and has excellent scratch resistance and antiglare properties.
A thermoplastic resin layer are k (k is an integer of 2 or more) will be stacked, and the i-th thermoplastic refractive index at a wavelength lambda in the range of wavelength 380nm~780nm the resin layer n _{i (lambda} ) Is a refractive index n _{i + 1} (λ) at a wavelength λ in the range of 380 nm to 780 nm of the ( _{i + 1} ) th thermoplastic resin layer, and the protective layer A, the polarizer, and the protective layer B having the relationship of the formula [1] A polarizing plate having a haze of 10 to 60%, which is laminated at least in this order.
| N _i (λ) −n _{i + 1} (λ) | ≦ 0.05 Formula [1]
However, i represents the integer of 1-k-1.
[Selection figure] None

Description

  The present invention relates to a polarizing plate and a liquid crystal display device, and more particularly, to a polarizing plate excellent in scratch resistance and antiglare property, which is free from visual defect due to light interference such as interference fringes, and the liquid crystal display device.

The polarizing plate used for a liquid crystal display device etc. is a laminated body which consists of a polarizer and a protective film. As a polarizer constituting this polarizing plate, a film in which iodine or a dichroic dye is adsorbed on a film obtained by forming a film of polyvinyl alcohol by a solution casting method and stretched in a boric acid solution is usually used.
On the other hand, a triacetyl cellulose film is widely used as a protective film constituting the polarizing plate. However, since the triacetylcellulose film has poor moisture resistance and gas barrier properties, the durability, heat resistance, mechanical strength, etc. of the polarizing plate are insufficient.

  In order to improve the durability and heat resistance of the polarizing plate, it has been proposed to use a protective film other than the triacetyl cellulose film. For example, Patent Document 1 proposes to use a laminated film including a norbornene-based resin layer and a resin layer having a small haze value as a protective film. And it is disclosed that a polarizing plate is obtained by attaching the protective film to a polarizer containing polyvinyl alcohol with the surface of the norbornene resin layer facing.

  In Patent Document 2, a resin layer having a smaller hygroscopic property than triacetyl cellulose and having a positive photoelastic constant and a resin layer having a smaller hygroscopic property than triacetyl cellulose and having a negative photoelastic constant are laminated. A protective film having a small photoelastic constant has been proposed. And the polarizing plate formed by sticking this protective film on the polarizer containing polyvinyl alcohol is disclosed.

JP 2005-115085 A JP 2000-206303 A

  However, in the polarizing plate obtained only by the techniques disclosed in Patent Document 1 and Patent Document 2, interference fringes are generated or scratches are caused by friction when attached to a liquid crystal display device or the like. Visibility from may be poor.

  An object of the present invention is to provide a polarizing plate suitable for a liquid crystal display device or the like, which is free from visual defect due to interference of light such as interference fringes and is excellent in scratch resistance and antiglare property.

As a result of studies conducted by the present inventor to achieve the above object, the present invention is a film in which k thermoplastic resin layers (k is an integer of 2 or more) are laminated, and the 380 nm of the i-th thermoplastic resin layer. The refractive index n _i (λ) at the wavelength λ in the range of ˜780 nm and the refractive index n _{i + 1} (λ) at the wavelength λ in the range of 380 nm to 780 nm of the i + 1th thermoplastic resin layer satisfy a specific relationship. It has been found that light interference such as interference fringes is hardly caused by a polarizing plate having a film and a polarizer laminated and having a haze of 10 to 60%.

In addition to the fact that each of the thermoplastic resin layers is made of a material having a haze of 0.5% or less and contains an amorphous thermoplastic resin, the humidity expansion coefficient β _{i of} the i-th thermoplastic resin layer and A polarizing plate having a haze of 10 to 60% obtained by laminating a film in which the humidity expansion coefficient β _{i + 1 of} the (i + 1) th thermoplastic resin layer satisfies a specific relationship and a polarizer is laminated in a high temperature and high humidity environment. Also found that the polarizer and the protective layer do not peel off.

The refractive index n ₁ (λ) at a wavelength λ in the range of 380 nm to 780 nm of the thermoplastic resin layer closest to the polarizer (first), and the range of 380 nm to 780 nm of polyvinyl alcohol contained in the polarizer A polarizing plate having a haze of 10 to 60% obtained using a film satisfying a specific relationship with a refractive index n _b (λ) at a wavelength λ of the above has a high contrast, no visual defect due to streaks, and the like. It has been found that it is excellent in flexibility and scratch resistance.
The present invention has been completed based on these findings.

The present invention includes the following.
(1) Refractive index n _i (λ) at a wavelength λ of 380 nm to 780 nm of the i-th thermoplastic resin layer, in which k thermoplastic resin layers (k is an integer of 2 or more) are laminated. And the refractive index n _{i + 1} (λ) at a wavelength λ in the range of 380 nm to 780 nm of the ( _{i + 1} ) th thermoplastic resin layer is the formula [1] (where i represents an integer of 1 to k−1). A protective layer A having the relationship
A polarizer and a protective layer B are laminated in at least this order.
A polarizing plate having a haze of 10 to 60%.
| N _i (λ) −n _{i + 1} (λ) | ≦ 0.05 Formula [1]

(2) The protective layer A is a polarizing plate as described in (1) whose absolute value of a photoelastic coefficient is 10 * 10 <^-12> Pa < ^{-1 >} or less.
(3) The polarizing plate for liquid crystal display according to (1) or (2), wherein an antiglare layer is laminated directly or via another layer on the surface of the protective layer A far from the polarizer.
(4) The antiglare layer and the antireflection layer are laminated on the surface of the protective layer A far from the polarizer, directly or via another layer, according to any one of (1) to (3) A polarizing plate for liquid crystal display.
(5) The polarizing plate for liquid crystal displays according to any one of (1) to (4), wherein the protective layer A contains an ultraviolet absorber.
(6) The polarizing plate for liquid crystal displays according to any one of (1) to (5), wherein the surface of the protective layer A on the side far from the polarizer has an uneven shape.
(7) The layer according to any one of (1) to (6), including a layer including a region where the refractive index is discontinuous, directly or via another layer, on the surface of the protective layer A far from the polarizer. Polarizing plate.
(8) A liquid crystal display device comprising the polarizing plate according to any one of (1) to (7).

The polarizing plate of the present invention is less likely to cause interference of light such as interference fringes, and is less likely to cause scratches due to friction. Therefore, it is difficult to cause poor visibility when attached to a display screen.
Since the retardation of the polarizing plate of the present invention hardly changes due to heat or stress due to deformation, even if unpredictable and undesirable stress is applied, light leakage, color unevenness, coloring, etc. hardly occur near the edge of the display screen. . Further, the polarizer and the protective layer hardly peel even under a harsh environment.
The polarizing plate of the present invention has high contrast and does not generate streaks. Moreover, since it is excellent in flexibility and scratch resistance, visibility does not become poor. The polarizing plate of the present invention is particularly suitable for a liquid crystal display device having a large area.

It is a figure which shows the refractive index n ((lambda)) of each resin layer used in the present Example. It is a figure which shows distribution of the absolute value of the difference of the refractive index n ((lambda)) of each resin layer used in the present Example. It is a figure which shows distribution of the absolute value of the difference of the refractive index n ((lambda)) of the polyvinyl alcohol used in the present Example, and the refractive index n ((lambda)) of a polymethylmethacrylate layer.

  COP: alicyclic olefin polymer, PC: polycarbonate resin, PMMA: polymethyl methacrylate resin, PVA: polyvinyl alcohol

The polarizing plate of the present invention is formed by laminating a protective layer A, a polarizer, and a protective layer B in which k thermoplastic resin layers are laminated (k is an integer of 2 or more) in this order.
There is no particular limitation on the method of laminating the protective layer A (the protective layer on the viewing side) and the protective layer B (the protective layer on the liquid crystal cell side) on the polarizer. For example, the protective film and the protective layer B that become the protective layer A What is necessary is just to employ | adopt the general method of laminating | stacking the protective film which becomes to a polarizer via an acrylic adhesive etc. as needed.
The polarizing plate of the present invention has a haze of 10 to 60%, preferably 30 to 60%. By having a haze in such a range, reflection can be prevented and antiglare properties can be improved. The method for adjusting the haze of the polarizing plate is not particularly limited. As will be described later, a method for forming irregularities on the surface on the side far from the polarizer of the protective layer A, or a method for laminating an antiglare layer, which will be a visible side protective layer. And so on.

(Protective layer A)
The protective layer A is formed by stacking k (k is an integer of 2 or more) thermoplastic resin layers. In other words, the protective layer A is formed by laminating the first thermoplastic resin layer to the kth thermoplastic resin layer in this order. k is usually 2 to 7, preferably 3 to 5.
The thermoplastic resin constituting the thermoplastic resin layer is, for example, polycarbonate resin, polyether sulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polysulfone resin, polyarylate resin, polyethylene resin, polyvinyl chloride resin, diacetyl. It can be selected from cellulose, triacetyl cellulose, alicyclic olefin polymer, and the like.

Examples of the alicyclic olefin polymer include a cyclic olefin random multiple copolymer described in JP-A No. 05-310845, a hydrogenated polymer described in JP-A No. 05-97978, and JP-A No. 11-124429. And thermoplastic dicyclopentadiene-based ring-opening polymers and hydrogenated products thereof. Note that not all of the illustrated thermoplastic resins can be applied to the present invention, and some of the same kind of thermoplastic resins may or may not satisfy the following requirements. Select as appropriate.
The thermoplastic resin used in the present invention includes colorants such as pigments and dyes, fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, and solvents. These compounding agents may be appropriately blended.

  Lubricants include inorganic particles such as silicon dioxide, titanium dioxide, magnesium oxide, calcium carbonate, magnesium carbonate, barium sulfate, and strontium sulfate, as well as polymethyl acrylate, polymethyl methacrylate, polyacrylonitrile, polystyrene, cellulose acetate, and cellulose Organic particles such as acetate propionate can be mentioned. As particles constituting the lubricant, organic particles are preferable, and among these, particles made of polymethyl methacrylate are particularly preferable.

  As the lubricant, elastic particles made of a rubber-like elastic body can be used. Examples of the rubber-like elastic body include an acrylate-based rubber-like polymer, a rubber-like polymer containing butadiene as a main component, and an ethylene-vinyl acetate copolymer. Examples of the acrylic ester rubbery polymer include those containing butyl acrylate, 2-ethylhexyl acrylate, or the like as a main component. Of these, acrylate polymers based on butyl acrylate and rubbery polymers based on butadiene are preferred. The elastic particles may be formed by laminating two kinds of polymers. Typical examples thereof include an alkyl acrylate such as butyl acrylate, a styrene grafted rubber elastic component, and a methyl methacrylate. Examples thereof include elastic particles in which a hard resin layer made of a copolymer of a rate and / or methyl methacrylate and an alkyl acrylate forms a layer with a core-shell structure.

  The elastic particles generally have a number average particle size of 2.0 μm or less, preferably 0.1 to 1.0 μm, and more preferably 0.1 to 0.5 μm when dispersed in a thermoplastic resin. Even if the primary particle diameter of the elastic particles is small, if the number average particle diameter of the secondary particles formed by aggregation or the like is large, the protective layer A has a high haze (cloudiness) and a low light transmittance. , Not suitable for display screen. Moreover, when the number average particle size becomes too small, the flexibility tends to decrease.

In the present invention, the refractive index n _p (λ) of the elastic particles at a wavelength of 380 nm to 780 nm is between the refractive index n _r (λ) of the thermoplastic resin serving as the matrix at a wavelength of 380 nm to 780 nm. It is preferable to satisfy the relationship.
| N _p (λ) −n _r (λ) | ≦ 0.05 Formula [2]
In particular, it is more preferable that | n _p (λ) −n _r (λ) | ≦ 0.045. Note that n _p (λ) and n _r (λ) are average values of the main refractive indices at the wavelength λ. When the value of | n _p (λ) −n _r (λ) | exceeds the above value, transparency may be impaired due to interface reflection caused by a difference in refractive index at the interface.

  The thermoplastic resin used in the present invention preferably has a light transmittance in the visible region of 400 to 700 nm at a thickness of 1 mm of 80% or more, more preferably 85% or more, and even more preferably 90% or more. . The thermoplastic resin is preferably an amorphous resin from the viewpoint of transparency. In addition, the thermoplastic resin preferably has a glass transition temperature of 60 to 200 ° C, more preferably 100 to 180 ° C. The glass transition temperature can be measured by differential scanning calorimetry (DSC).

The protective layer A has a refractive index n _i (λ) at a wavelength λ ranging from 380 nm to 780 nm of the i-th thermoplastic resin layer at a wavelength λ ranging from 380 nm to 780 nm of the i + 1-th thermoplastic resin layer. The refractive index n _{i + 1} (λ) and the relationship of the formula [1] are satisfied.
| N _i (λ) −n _{i + 1} (λ) | ≦ 0.05 Formula [1]
However, i represents the integer of 1-k-1. In particular, the protective layer A more preferably satisfies the relationship of | n _i (λ) −n _{i + 1} (λ) | ≦ 0.045.
Note that n _i (λ) and n _{i + 1} (λ) are average values of the main refractive indices at the wavelength λ. When the value of | n _i (λ) −n _{i + 1} (λ) | exceeds the above value with respect to a part or all of i = 1 to k−1, it is caused by a difference in refractive index at the interface. Interference fringes may occur on the surface of the protective layer A due to the interface reflection. Note that the i-th thermoplastic resin layer and the (i + 1) -th thermoplastic resin layer adjacent to each other may be in direct contact with each other or may be in contact with each other through an adhesive layer described later.

  In the protective layer A, the water absorption rate of at least one of the laminated thermoplastic resin layers can be 0.5% or less, and further can be 0.1% or less. The durability of the polarizing plate can be enhanced by using a protective layer A having a low water absorption rate. The water absorption rate of the thermoplastic resin layer can be determined according to JIS K7209.

Protective layer A value defined by the in-plane retardation _{Re (Re = d × (n} x -n y), n x, n y in-plane principal refractive index of the protective layer A _{(n x} ≧ _{n y} ); D is an average thickness of the protective layer A) is preferably small, and specifically, in-plane retardation Re is preferably 50 nm or less, more preferably 10 nm or less at a wavelength of 550 nm.

  The thickness of each thermoplastic resin layer constituting the protective layer A is not particularly limited, but the thickness of the kth thermoplastic resin layer is usually 5 to 100 μm, preferably 10 μm or more, more preferably 10-50 μm. The thickness of the 1st thermoplastic resin layer is 5-100 micrometers normally, Preferably it is 10-50 micrometers. At this time, it is preferable that the thickness of the kth thermoplastic resin layer and the thickness of the first thermoplastic resin layer are substantially equal. Specifically, the absolute value of the difference between the thickness of the first thermoplastic resin layer and the thickness of the kth thermoplastic resin layer is preferably 20 μm or less, and more preferably 10 μm or less. .

Moreover, the thickness of the intermediate | middle thermoplastic resin layer provided as needed between a 1st thermoplastic resin layer and a kth thermoplastic resin layer is 5-100 micrometers normally, Preferably it is 10 ~ 50 μm. The ratio of the thickness of the intermediate thermoplastic resin layer to the thickness of the kth thermoplastic resin layer or the thickness of the first thermoplastic resin layer (intermediate layer thickness: first layer or kth The thickness of the layer is not particularly limited, but is preferably 5: 1 to 1: 5.
The thickness of the entire protective layer A is usually 20 to 200 μm, preferably 40 to 100 μm.

  The thermoplastic resin forming the first thermoplastic resin layer is preferably selected from acrylic resins, alicyclic olefin polymers, and polycarbonate resins, and particularly preferably selected from acrylic resins such as polymethyl methacrylate resins.

  The thermoplastic resin that forms the kth thermoplastic resin layer is preferably hard. Specifically, a pencil hardness (JIS K5600-5-4, where the test load is 500 g) is preferably harder than 2H. As the thermoplastic resin for forming the kth thermoplastic resin layer, the most preferable one is selected from acrylic resins such as polymethyl methacrylate resin.

  In addition, when the polarizing plate is formed by providing the protective layer A on the polarizer, in order to prevent warping, bending, rounding, etc. of the polarizing plate, a thermoplastic resin that forms the kth thermoplastic resin layer; The thermoplastic resin forming the second thermoplastic resin layer is preferably selected from the same kind of thermoplastic resin.

  The laminated thermoplastic resin layers may be in direct contact with each other or may be in contact with each other through an adhesive layer. The average thickness of the adhesive layer is usually 0.01 to 30 μm, preferably 0.1 to 15 μm. The adhesive layer is a layer having a tensile fracture strength according to JIS K7113 of 40 MPa or less. Adhesives constituting the adhesive layer include acrylic adhesives, urethane adhesives, polyester adhesives, polyvinyl alcohol adhesives, polyolefin adhesives, modified polyolefin adhesives, polyvinyl alkyl ether adhesives, rubber Adhesives, vinyl chloride-vinyl acetate adhesives, SEBS adhesives, ethylene adhesives such as ethylene-styrene copolymers, ethylene- (meth) acrylic acid methyl copolymers, ethylene- (meth) acrylic acids Examples include acrylic ester adhesives such as ethyl copolymers.

The moisture permeability of the protective layer A is not particularly limited, but is preferably 40 g / (m ² · 24 h) or less, and more preferably 10 g / (m ² · 24 h) or less. The film has a water vapor transmission rate of 40 ° C. and 92% R.D. H. It can be measured by the cup method described in JIS Z 0208 under the test conditions of leaving in an environment of

Further, the protective layer A has a tensile modulus of elasticity of the i-th thermoplastic resin layer as A _i , and a tensile modulus of elasticity of the i + 1-th thermoplastic resin layer as A _{i + 1.} Thus, | A _{i + 1} −A _i | ≧ 0.5 GPa. By setting it as such a structure, the intensity | strength and flexibility of a polarizing plate provided with the said protective film can be improved, preventing the fall of the optical performance by an interference fringe etc. The tensile modulus of elasticity Ak of the _kth thermoplastic resin layer can be 3.0 GPa or more. Tensile modulus A _k of the k th thermoplastic resin layer may be a larger than the tensile modulus A _k-1 of the k-1 th thermoplastic resin layer adjacent thereto. Further, the tensile elastic modulus A1 of the _first thermoplastic resin layer can be 3.0 GPa or more.

  In addition, the total number of laminated thermoplastic resin layers is preferably 7 layers or less, and more preferably 5 layers or less. When the number is larger than the number of layers, it may be difficult to control the surface shape and thickness of each layer.

  Further, in the protective layer A, it is preferable that the surface of the k-th thermoplastic resin layer is not formed with linear concave portions or linear convex portions, and the surface is flat. Even if linear concave portions or linear convex portions are formed, linear concave portions having a depth of less than 50 nm or a width of more than 500 nm, or lines having a height of less than 50 nm or a width of more than 500 nm. It is preferable that it is a convex part. More preferably, it is a linear concave portion having a depth of less than 30 nm or a width of 700 nm, and a linear convex portion having a height of less than 30 nm or a width of greater than 700 nm. Further, it is preferable that the above-described linear concave portions and linear convex portions are not formed on the surface of the first thermoplastic resin layer as well as the kth thermoplastic resin. By not forming the linear concave portion or the linear convex portion, it is possible to prevent light leakage or optical interference.

  The depth of the linear concave portion described above, the height of the linear convex portion, and the width thereof can be obtained by the following method. The protective layer A is irradiated with light, the transmitted light is projected onto the screen, and the light or dark stripes of light appearing on the screen (this part has the depth of the linear recesses and the height of the linear protrusions). Cut out at 30 mm square. The surface of the cut film piece is observed using a three-dimensional surface structure analysis microscope (field region 5 mm × 7 mm), converted into a three-dimensional image, and a cross-sectional profile in the MD direction is obtained from the three-dimensional image. The cross-sectional profile is obtained at 1 mm intervals in the visual field region. In this cross-sectional profile, an average line is drawn, the length from the average line to the bottom of the linear recess is the linear recess depth, or the length from the average line to the top of the linear protrusion is the linear protrusion height. It becomes. The distance between the intersection of the average line and the profile is the width. The maximum values are obtained from the measured values of the linear concave portion depth and the linear convex portion height, respectively, and the width of the linear concave portion or the linear convex portion showing the maximum value is obtained. The maximum value of the linear recess depth and the height of the linear convex portion obtained from the above, the width of the linear concave portion and the width of the linear convex portion showing the maximum value, the depth of the linear concave portion of the film Let the height of the linear protrusions and their widths.

  The thermoplastic resin layer having no linear protrusions and linear recesses of such a size, for example, in the T-die type extrusion molding method, reduces the surface roughness of the lip part of the die. Plating chrome, nickel, titanium, etc., spraying ceramics on the tip of the lip, TiN, TiAlN, TiC, CrN, DLC (diamond-like carbon), etc. by the PVD (Physical Vapor Deposition) method etc. To form a film, to uniformly adjust the temperature distribution around the molten resin immediately after being extruded from the die, the air flow, etc., and to select a resin having the same melt flow rate value as the resin that forms the thermoplastic resin layer, In the cast molding method, the cast support film with a small surface roughness is used. It can be obtained by using means such as using a rum, reducing the surface roughness of the coating machine, and further adjusting the temperature distribution, drying temperature, and drying time during drying of the coating layer.

  The protective layer A is not particularly limited by its production method, for example, one obtained by laminating a single-layer thermoplastic resin film, one obtained by coextrusion molding of a plurality of thermoplastic resins, thermoplastic Examples thereof include those obtained by casting a thermoplastic resin solution on a resin film. Among these, from the viewpoint of productivity, the protective layer A is preferably obtained by coextrusion molding. In the case of coextrusion molding, since a complicated process (for example, a drying process or a coating process) is not required, there is an advantage that it is possible to provide a film with less external foreign matters such as dust and excellent optical characteristics.

  In order to adjust the haze value of the polarizing plate of the present invention, an appropriate antiglare means can be provided on the outer surface of the protective layer A, preferably on the surface far from the polarizer (the outer surface of the kth layer). As the anti-glare means, for example, (a) a fine unevenness is formed on the side far from the polarizer to cause light scattering, and (b) a layer composed of two or more components having a difference in refractive index is formed. As a result, there are those that cause light scattering due to a difference in refractive index.

(Anti-glare means)
The method for forming fine irregularities is not particularly limited, and an appropriate method can be adopted. For example, in a state in which the protective layer A is directly or in a state where other layers are laminated, the unevenness is transferred by a method of imparting fine unevenness by a method of roughening by a method such as sandblasting, embossing roll, chemical etching, or a shaping film. In addition to methods (for example, JP-A-2005-331901), a method of dispersing fine particles in a resin constituting the protective layer, and a method of forming an antiglare layer made of a transparent resin material containing fine particles on the protective layer A (Japanese Patent Laid-Open No. 11-305010, Japanese Patent Laid-Open No. 2002-107512, Japanese Patent Laid-Open No. 10-246802, etc.). These methods may be used in combination of two or more.
In addition, the degree of unevenness is not particularly limited as long as the haze value is in the above range. Usually, the center line average roughness (Ra) is 0.04 to 0.5 μm, and the average peak-to-valley spacing (Sm) is 20 to 100 μm. It is.

  As the transparent resin material used for forming the antiglare layer, fine particles can be dispersed, sufficient strength as a film can be given, and a transparent material can be used without particular limitation. Examples of the resin include thermosetting resins, thermoplastic resins, ultraviolet curable resins, and electron beam curable resins. Among these, an ultraviolet curable resin that can efficiently form an antiglare layer by a simple processing operation by a curing treatment by ultraviolet irradiation is preferable.

  Examples of the ultraviolet curable resin include various types such as polyester, acrylic, urethane, amide, silicone, and epoxy, and these include ultraviolet curable monomers, oligomers, polymers, and the like. Examples of the ultraviolet curable resin preferably used include those having an ultraviolet polymerizable functional group, particularly those containing an acrylic monomer or oligomer having 2 or more, particularly 3 to 6 functional groups.

Further, the transparent resin material may contain 10 parts by weight or more and 100 parts by weight or less of solvent-drying resin with respect to 100 parts by weight of the resin. As the solvent-drying resin, a thermoplastic resin is mainly used.
In particular, when a mixture of polyester acrylate and polyurethane acrylate is used as the ionizing radiation curable resin, polymethyl methacrylate, polybutyl methacrylate, or cellulose acetate propionate is preferably used as the solvent-drying resin.

  The fine particles may be inorganic fine particles or organic fine particles, or may be modified fine particles such as those obtained by coating inorganic fine particles with an organic material. For example, fine particles that exhibit a diffusion effect due to a difference in refractive index with the transparent resin material and fine particles that exhibit a diffusion effect by forming irregularities on the surface of the resin layer can be used in combination.

  The shape of the fine particles may be a true sphere, an ellipse or the like, preferably a true sphere. Examples of the inorganic fine particles include silica and alumina. The organic fine particles are preferably resin beads having a refractive index of 1.40 to 1.60. Resin beads include polymethyl methacrylate beads (refractive index: 1.49), melamine beads (refractive index 1.57), polycarbonate beads (refractive index: 1.58), polystyrene beads (refractive index: 1.60). And acrylic styrene resin beads (refractive index: 1.57), polyvinyl chloride beads (refractive index: 1.54), and polyethylene beads.

  These resin beads preferably have a particle diameter of 1 to 8 μm, and are used in an amount of 5 to 22 parts by weight, preferably 10 to 25 parts by weight, based on 100 parts by weight of the resin. When such resin beads are mixed, the resin beads precipitated on the bottom of the container at the time of coating need to be stirred and dispersed well. In order to eliminate such inconvenience, silica beads having a particle diameter of 0.5 μm or less, preferably 0.1 to 0.25 μm may be included in the coating liquid as an anti-settling agent for resin beads. The more silica beads are added, the more effective the prevention of sedimentation of the resin beads is, but it adversely affects the transparency of the coating film. Therefore, the amount of the anti-settling agent is preferably less than 0.1 parts by weight with respect to 100 parts by weight of the resin, to the extent that the transparency as the antiglare layer is not impaired.

  The fine particles may exist in a uniformly dispersed form in the cured film or may be unevenly distributed in the film thickness direction. The fine particles may be present in a form protruding from the surface. However, from the viewpoint of improving the clarity of the transmitted image described later, the fine particles protruding from the surface of the antiglare layer is preferably 0.5 μm or less. .

  The transparent resin material for forming the antiglare layer may contain other materials such as an antistatic agent, a leveling agent, and an ultraviolet absorber as necessary.

  As a method for forming an antiglare function by internal scattering by forming a layer including a region where the refractive index is discontinuous, two or more kinds of compositions having different refractive indexes are used to form a phase separation structure by ultraviolet irradiation or the like. And a method of forming a layer containing fine particles having a refractive index different from that of the transparent resin material and the transparent resin material.

  As a method for forming a layer having a phase separation structure, for example, a known method such as a method described in Japanese Patent No. 3446737 using two kinds of photopolymerizable monomers and / or oligomers can be employed.

  Examples of these photopolymerizable monomers and oligomers include 2,4,6-tribromophenyl acrylate, tribromophenoxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, tetrahydrofurfuryl acrylate, ethyl carbitol acrylate Pentenyloxyethyl acrylate, phenyl carbitol acrylate, polyol polyacrylate, isocyanuric acid skeleton polyacrylate, melamine acrylate, hydantoin skeleton polyacrylate, urethane acrylate, and the like.

  Two or more kinds of the above photopolymerizable monomers and oligomers having different refractive indexes are used. Examples of the combination include two types selected from monomers, one type of monomer and one type of oligomer, two types selected from oligomers, or a combination of these in addition to one or more types of monomers or oligomers. In these combinations, it is preferable that at least two of them have a refractive index difference of 0.03 or more in order to obtain a necessary light scattering ability.

  Furthermore, it is preferable to use a photopolymerization initiator in order to improve the curability of the composition containing the materials having different refractive indexes. Examples of the photopolymerization initiator include benzophenone, 2-hydroxy-2-methylpropiophenone, benzyl, Michler's ketone, and 2-chlorothioxanthone as exemplified in JP-A-7-64069.

  A composition containing a material having a different refractive index can contain a compound having a refractive index different from that of a photopolymerizable monomer or oligomer and having no photopolymerizability. Examples include styrene resins such as polystyrene, acrylic resins such as polymethyl methacrylate, resins such as polyethylene oxide, polyvinyl pyrrolidone, and polyvinyl alcohol, and plastic additives such as organic halogen compounds, organic silicon compounds, plasticizers, and stabilizers. It is done. These can also be mix | blended in said composition as a high refractive index component or a low refractive index component. The difference in refractive index between the photopolymerizable monomer or oligomer and the non-photopolymerizable compound is preferably 0.03 or more.

  Furthermore, 0.01 to 5 parts by weight of a filler having an average particle diameter of 0.05 to 20 μm can be blended, or an ultraviolet absorber can be added.

  The transparent resin material for forming the antiglare layer utilizing the scattering phenomenon caused by the difference in refractive index between the transparent resin material and the fine particles can be selected from those exemplified as the transparent resin material constituting the fine uneven layer.

  In order to obtain an antiglare effect due to the difference in refractive index between the transparent resin material and the fine particles, the difference between the refractive index of the transparent resin material and the refractive index of the fine particles is preferably 0.03 or more, more preferably 0.04. It is 0.5 or less. When the difference in refractive index is less than 0.03, the light diffusion effect cannot be obtained. When the difference in refractive index is greater than 0.5, the light diffusibility is too strong and the image sharpness is deteriorated.

  The film thickness (when cured) of the antiglare layer is 0.1 to 20 μm, preferably 0.8 to 10 μm. When the film thickness is within this range, the function as an antiglare layer can be sufficiently exhibited.

  In addition, when forming the anti-glare layer by a cured film on the said transparent base material, a hydrophilic treatment can be given to the surface of a transparent base material. The hydrophilic treatment means is not particularly limited, and for example, a surface treatment method such as corona discharge treatment, sputtering treatment, low-pressure UV irradiation, or plasma treatment can be suitably employed. Moreover, the process which improves adhesiveness, such as a thin-layer application | coating process of a cellulose-type material and a polyester-type material, can be given.

  Furthermore, in the polarizing plate of the present invention, functional layers such as a hard coat layer, an antireflection layer, and an antifouling layer may be formed on the surface of the protective layer A that is far from the polarizer.

(Hard coat layer)
The hard coat layer is preferably formed of a heat or photo-curing material that exhibits a hardness of “1H” or higher in a pencil hardness test (test plate is a glass plate) shown in JIS K5600-5-4. The pencil hardness of the protective layer A provided with the hard coat layer is preferably 4H or more. When the surface layer of the protective layer A is made of an acrylic resin, it is easy to adjust the pencil strength of the surface to 4H or higher with the hard coat layer.

  Examples of the hard coat layer material include organic hard coat materials such as organic silicone, melamine, epoxy, acrylic, and urethane acrylate; and inorganic hard coat materials such as silicon dioxide. Of these, urethane acrylate-based and polyfunctional acrylate-based hard coat materials are preferably used from the viewpoint of good adhesive strength and excellent productivity.

The hard coat layer has a refractive index _{n H} is between the refractive index _{n L} of the low refractive index layer stacked thereon, _{n H} ≧ 1.53, and _n ^H 1/2 -0.2 < It is preferable to have a relationship of n _L <n _H ^1/2 +0.2 in order to develop the antireflection function.

  This hard coat layer contains various fillers for the purpose of adjusting the refractive index, improving the flexural modulus, stabilizing the volume shrinkage, improving heat resistance, antistatic properties, antiglare properties, etc., as desired. You may squeeze it. Furthermore, various additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a leveling agent, and an antifoaming agent can be blended.

(Antireflection layer)
When using the polarizing plate of this invention for the display screen of a display, for example, it is preferable that the antireflection layer is further laminated | stacked on the said hard-coat layer. The antireflection layer is a layer for preventing the transfer of external light. The polarizing plate on which such an antireflection layer is laminated preferably has a reflectance at an incident angle of 5 ° and 430 to 700 nm of 2.0% or less and a reflectance at 550 nm of 1.0% or less. . The thickness of the antireflection layer is preferably 0.01 μm to 1 μm, and more preferably 0.02 μm to 0.5 μm. Examples of such an antireflection layer include those obtained by laminating a low refractive index layer having a refractive index smaller than that of the hard coat layer, preferably a refractive index of 1.30 to 1.45, and a low Examples thereof include those obtained by repeatedly laminating a refractive index layer and a high refractive index layer made of an inorganic compound.

  The material for forming the low refractive index layer is not particularly limited as long as the refractive index is lower than that of the protective layer A or the hard coat layer. For example, a resin material such as an ultraviolet curable acrylic resin, or a colloid in the resin. Examples thereof include hybrid materials in which inorganic fine particles such as silica are dispersed and sol-gel materials using metal alkoxides such as tetraethoxysilane. The material for forming the exemplified low refractive index layer may be a polymerized polymer, or a monomer or oligomer serving as a precursor. Moreover, it is preferable that each material contains the compound containing a fluorine group in order to provide the surface antifouling property.

Examples of the sol-gel material containing a fluorine group include perfluoroalkylalkoxysilane. As perfluoroalkyl alkoxysilane, for example, general formula: CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OR) ₃ (wherein R represents an alkyl group having 1 to 5 carbon atoms, n is And an integer of 0 to 12). Specifically, for example, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecyltri And ethoxysilane. Among these, the compound wherein n is 2 to 6 is preferable.

  The low refractive index layer is preferably made of a cured product of a thermosetting fluorine-containing compound or an ionizing radiation curable fluorine compound. The dynamic friction coefficient of the cured product is preferably 0.03 to 0.15, and the contact angle with water is preferably 90 to 120 degrees. Examples of the curable fluorine-containing polymer compound include a perfluoroalkyl group-containing silane compound (for example, (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane) and the like, and a fluorine-containing fluorine-containing polymer having a crosslinkable functional group. A copolymer is mentioned.

  The fluorine-containing polymer having a crosslinkable functional group is obtained by copolymerizing a fluorine-containing monomer and a monomer having a crosslinkable functional group, or by copolymerizing a fluorine-containing monomer and a monomer having a functional group, and then in the polymer. It can be obtained by adding a compound having a crosslinkable functional group to the functional group.

  Fluoroolefins such as fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole; biscoat 6FM (Osaka Organic) Chemical), M-2020 (manufactured by Daikin), (meth) acrylic acid partial or fully fluorinated alkyl ester derivatives, fully or partially fluorinated vinyl ethers, and the like.

  Monomers having a crosslinkable functional group or compounds having a crosslinkable functional group include monomers having a glycidyl group such as glycidyl acrylate and glycidyl methacrylate; monomers having a carboxyl group such as acrylic acid and methacrylic acid; hydroxyalkyl acrylate and hydroxyalkyl Monomers having a hydroxyl group such as methacrylate; methylol acrylate, methylol methacrylate; monomers having a vinyl group such as allyl acrylate and allyl methacrylate; monomers having an amino group; monomers having a sulfonic acid group;

  As a material for forming the low refractive index layer, a material containing a sol in which fine particles such as silica, alumina, titania, zirconia, magnesium fluoride and the like are dispersed in an alcohol solvent is used because it can improve scratch resistance. Can do. From the viewpoint of antireflection properties, the fine particles preferably have a lower refractive index. Such fine particles may have voids, and silica hollow fine particles are particularly preferable. The average particle size of the hollow fine particles is preferably 5 nm to 2,000 nm, and more preferably 20 nm to 100 nm. Here, the average particle diameter is a number average particle diameter obtained by observation with a transmission electron microscope.

  The thickness of the low refractive index layer is not particularly limited, but is preferably about 0.05 to 0.3 μm, particularly preferably 0.1 to 0.3 μm.

(Anti-fouling layer)
In order to improve the antifouling property of the low refractive index layer, an antifouling layer may be further provided on the low refractive index layer. The antifouling layer is a layer that can impart water repellency, oil repellency, sweat resistance, antifouling properties and the like to the surface. As a material used for forming the antifouling layer, a fluorine-containing organic compound is suitable. Examples of the fluorine-containing organic compound include fluorocarbon, perfluorosilane, or a polymer compound thereof. As a method for forming the antifouling layer, a physical vapor deposition method such as vapor deposition or sputtering, a chemical vapor deposition method, a wet coating method, or the like can be used depending on the material to be formed. The average thickness of the antifouling layer is preferably 1 to 50 nm, more preferably 3 to 35 nm.

  In addition to these layers, other layers such as a gas barrier layer, a transparent antistatic layer, a primer layer, an electromagnetic shielding layer, and an undercoat layer may be provided on the protective layer A.

When the functional layer as described above is formed, it is preferable to perform chemical treatment on the surface to be formed. Examples of the chemical treatment include corona discharge treatment, sputtering treatment, low-pressure UV irradiation treatment, and plasma treatment. In addition to the chemical treatment, the protective layer A may be subjected to mechanical treatment such as etching, sandblasting, embossing roll, etc. for the purpose of enhancing adhesion with the functional layer and imparting antiglare properties.
There is no particular limitation on the method for forming these functional layers, and a general method may be employed for forming each functional layer.

(Polarizer)
The polarizer used in the present invention is obtained by adsorbing iodine or dichroic dye on a polyvinyl alcohol film and then uniaxially stretching in a boric acid bath, or iodine or dichroic dye on a polyvinyl alcohol film. And the like obtained by adsorbing and stretching, and further modifying a part of the polyvinyl alcohol unit in the molecular chain into a polyvinylene unit. In addition, a polarizer having a function of separating polarized light into reflected light and transmitted light, such as a grid polarizer, a multilayer polarizer, and a cholesteric liquid crystal polarizer, can also be used as the polarizer. Among these, a polarizer comprising polyvinyl alcohol is preferable. The polarization degree of the polarizer is preferably 98% or more, more preferably 99% or more. The thickness (average thickness) of the polarizer is preferably 5 μm to 80 μm.

(Protective layer B)
The protective layer B used in the present invention may be the same as the protective layer A described above, or may be a protective layer conventionally used for polarizing plates. The protective layer B is preferably formed of a material having a light transmittance in the visible region of 400 to 700 nm at a thickness of 1 mm of 80% or more, more preferably 85% or more, and still more preferably 90% or more. As the resin constituting the protective layer conventionally used for polarizing plates, polycarbonate resin, polyethersulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polysulfone resin, polyarylate resin, polyethylene resin, polystyrene Examples thereof include resins, polyvinyl chloride resins, cellulose esters, and alicyclic olefin polymers. Examples of the alicyclic olefin polymer include cyclic olefin random multi-component copolymers described in JP-A No. 05-310845 or US Pat. No. 5,179,171, JP-A No. 05-97978 or US Pat. No. 5,202,388. Examples thereof include the hydrogenated polymers described, thermoplastic dicyclopentadiene ring-opening polymers described in JP-A No. 11-124429 (WO 99/20676), and hydrogenated products thereof. .

  The polarizing plate of the present invention may be obtained by laminating a film showing birefringence on the protective layer B side in addition to the protective layer A, the polarizer and the protective layer B described above. In this case, the protective layer B is preferably optically isotropic. Specifically, Re is preferably 10 nm or less, more preferably 5 nm or less. The absolute value of Rth is preferably 10 nm or less, more preferably 5 nm or less.

A film showing birefringence may be used as the protective layer B.
When a film showing birefringence is used as the protective layer B, or when a film showing birefringence is laminated on the protective layer B side, it has a function of optical compensation such as color compensation, viewing angle compensation, etc. The visibility of the display device is improved.

  Birefringent films include those obtained by stretching a film containing a thermoplastic resin, those obtained by forming an optically anisotropic layer on an unstretched thermoplastic resin film, and optical on a film containing a thermoplastic resin. After forming the anisotropic layer, it can be further stretched. The film showing birefringence may be a single layer film or a laminated film.

<A stretched film containing a thermoplastic resin>
The thermoplastic resin used for obtaining a film exhibiting birefringence can be selected from those exemplified as the resin constituting the protective layer B. Of these, alicyclic olefin polymers and cellulose esters are preferred because of their excellent transparency, low birefringence, dimensional stability, and the like. A retardation increasing agent can be added to these resins as needed.

  As a method of stretching the film containing the thermoplastic resin, a uniaxial stretching method such as a method of stretching uniaxially in a transverse direction using a tenter; a gap between fixed clips is opened and a guide rail spreads simultaneously with stretching in the longitudinal direction. Simultaneous biaxial stretching method that stretches in the transverse direction depending on the angle, or sequential stretching that stretches in the longitudinal direction using the difference in peripheral speed between rolls and then grips both ends of the clip and stretches in the transverse direction using a tenter. Biaxial stretching method such as axial stretching method; Tenter stretching machine that can add feed force or pulling force or pulling force at different speeds in the horizontal or vertical direction; Alternatively, using a tenter stretching machine that can add a pulling force or a pulling force so that the moving distance is the same and the stretching angle θ can be fixed, or the moving distance is different. How to order stretching: and the like.

  Stretching can usually be performed in the range of Tg to Tg + 20 ° C., where Tg is the glass transition temperature of the resin forming the protective layer B, particularly the resin having the lowest glass transition temperature. Moreover, what is necessary is just to adjust a draw ratio in order to obtain a desired optical characteristic in the range of 1.1 to 3.0 times normally.

<Those formed with an optically anisotropic layer on an unstretched thermoplastic resin film>
For the formation of the optically anisotropic layer, a polymer compound or a liquid crystal compound can be used. These may be used alone or in combination.

  As the polymer compound, polyamide, polyimide, polyester, polyether ketone and the like can be used. Specific examples include compounds described in JP-T-8-511812 (International Publication No. WO94 / 24191) and JP-T 2000-511296 (International Publication No. WO97 / 44704).

  Further, the liquid crystalline compound may be a rod-like liquid crystal or a discotic liquid crystal, and these include a polymer liquid crystal or a low-molecular liquid crystal, and those in which a low-molecular liquid crystal is cross-linked and no longer exhibits liquid crystallinity. . Preferable examples of the rod-like liquid crystal include those described in JP 2000-304932A. Preferred examples of the discotic liquid crystal include those described in JP-A-8-50206.

  The optically anisotropic layer is generally formed by applying a solution of a discotic compound and other compounds (eg, plasticizer, surfactant, polymer, etc.) dissolved in a solvent onto the alignment film, drying, and then discotic nematic. It can be obtained by heating to the phase formation temperature and then cooling while maintaining the orientation state (discotic nematic phase). Alternatively, the optically anisotropic layer may be formed by applying a solution obtained by dissolving a discotic compound and another compound (for example, a polymerizable monomer, a photopolymerization initiator) in a solvent onto the alignment film, drying, and then discotic It can be obtained by heating to a nematic phase formation temperature, followed by polymerization by irradiation with UV light, etc., and further cooling.

  The thickness of the optically anisotropic layer is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and most preferably 0.7 to 5 μm. However, depending on the mode of the liquid crystal cell, it may be thickened (3 to 10 μm) in order to obtain high optical anisotropy. The method for forming the optically anisotropic layer is not particularly limited. For example, the polymer compound and / or liquid crystal compound is applied to a film containing a thermoplastic resin to produce a coating film, It can be produced by further stretching or shrinking the coating film.

The haze of the polarizing plate of the present invention obtained by laminating the above-mentioned layers is 10 to 60%, preferably 10 to 50%, and the total light transmittance of the polarizing plate is usually 25 to 50%, preferably 30 to 30%. 50%, more preferably 35-50%.
The total light transmittance of the protective layer A constituting the polarizing plate is preferably 70 to 100%, more preferably 80 to 100%, still more preferably 85 to 100% (for example, 85 to 95%), particularly preferably. Is about 90 to 100% (for example, 92 to 99%).

  The haze and total light transmittance can be measured using a haze meter “NDH-300A” manufactured by Nippon Denshoku Industries Co., Ltd.

In the preferred polarizing plate of the present invention, the protective layer A is laminated with the first thermoplastic resin layer facing the polarizer, and the first thermoplastic resin layer has a range of 380 nm to 780 nm. The refractive index n ₁ (λ) at the wavelength and the refractive index n _b (λ) at a wavelength in the range of 380 nm to 780 nm of polyvinyl alcohol satisfy the relationship of the formula [3].
| N ₁ (λ) −n _b (λ) | ≦ 0.05 Formula [3]

In the preferred polarizing plate of the present invention, the first thermoplastic resin layer of the protective layer A is laminated facing the polarizer side, and the refractive index of the first thermoplastic resin layer at a wavelength of 380 nm. n ₁ (380) and a refractive index n ₁ (780) at a wavelength of 780 nm, and a refractive index n _b (380) at a wavelength of 380 nm and a refractive index n _b (780) at a wavelength of 780 nm of the polyvinyl alcohol contained in the polarizer. Satisfy the relationship of the formula [4].
|| n ₁ (380) −n _b (380) |
− | N ₁ (780) −n _b (780) || ≦ 0.02 Formula [4]

That is, the difference between the refractive index of the first thermoplastic resin layer at a wavelength near the upper limit of the visible light region and the refractive index of polyvinyl alcohol contained in the polarizer is not so different from the difference at the wavelength near the lower limit. That's what it means. In particular, it is preferable that || n ₁ (380) −n _b (380) | — | n ₁ (780) −n _b (780) || ≦ 0.01. Note that n ₁ (380) and n ₁ (780) are average values of the main refractive indices at the respective wavelengths. n _b (380) and n _b (780) are the refractive indices of non-oriented polyvinyl alcohol.

  The polarizing plate of the present invention preferably exhibits a hardness of “3H” or higher, more preferably a hardness of “4H” or higher, in a pencil hardness test (test plate is a glass plate) shown in JIS K5600-5-4.

<Liquid crystal display device>
The liquid crystal display device of the present invention can be manufactured using the polarizing plate of the present invention. In the liquid crystal display device, a light source, an incident side polarizing plate, a liquid crystal cell, and an output side polarizing plate are usually arranged in this order. The polarizing plate of the present invention is provided on the emission side (viewing side) of the device. The liquid crystal display device of the present invention may further include a retardation plate, a brightness enhancement film, a light guide plate, a light diffusion plate, a light diffusion sheet, a light collection sheet, a reflection plate, and the like.

The present invention will be described in more detail with reference to examples and comparative examples. Parts and% are based on mass unless otherwise specified.
The protective films obtained in Examples and Comparative Examples were evaluated by the following methods.

<Refractive index of thermoplastic resin layer>
A resin is formed into a single layer, and a prism coupler (manufactured by Metricon, model 2010) is used. From the refractive index values at wavelengths of 633 nm, 407 nm, and 532 nm under the conditions of temperature 20 ° C. ± 2 ° C. and humidity 60 ± 5%, Caucy The refractive indexes of 380 nm and 780 nm are calculated according to the dispersion formula.

<Thickness of each resin layer>
After embedding the protective film in an epoxy resin, it was sliced using a microtome (RUB-2100, manufactured by Yamato Kogyo Co., Ltd.), and the cross section was observed and measured using a scanning electron microscope.

<Measurement of haze and total light transmittance>
Based on JIS K7361-1997, it measures using a turbidimeter (Nippon Denshoku Industries make, NDH-300A). In addition, about haze, the same measurement is performed 5 times and let the arithmetic mean value be a representative value of haze.
(Production of polarizer)
A polyvinyl alcohol film having a refractive index of 1.545 at a wavelength of 380 nm and a refractive index of 1.521 at a wavelength of 780 nm and a thickness of 75 μm is uniaxially stretched 2.5 times to obtain 0.2 g of iodine and 60 g of potassium iodide. Was immersed in an aqueous solution containing 30 g / L for 30 seconds and then immersed in an aqueous solution containing 70 g / L of boric acid and 30 g / L of potassium iodide and simultaneously uniaxially stretched 6.0 times and held for 5 minutes. Finally, it was dried at room temperature for 24 hours to obtain a polarizer P having an average thickness of 30 μm and a polarization degree of 99.95%.

Production Example 1
(Preparation of protective film 1)
A double flight type single screw extruder (effective screw length) in which a polymethyl methacrylate resin (tensile elastic modulus: 3.3 GPa; hereinafter may be referred to as “PMMA”) is provided with a leaf disk-shaped polymer filter having an opening of 10 μm. The ratio of L to screw diameter D (L / D = 28) is charged into a hopper, and the die slip surface roughness Ra is obtained by feeding the molten resin at an extruder outlet temperature of 260 ° C. and an extruder gear pump speed of 6 rpm. It was fed to one of the multi-manifold dies that was 0.1 μm.
On the other hand, an alicyclic olefin polymer (a ring-opening polymer hydrogenated product of norbornene-based monomer; Tg = 110 ° C., water absorption of less than 0.01%; hereinafter, may be referred to as “COP”) may have an opening of 10 μm. Was introduced into a double flight type single screw extruder equipped with a leaf disk-shaped polymer filter, and the molten resin was applied to the other side of the multi-manifold die having a die slip surface roughness Ra of 0.1 μm at an extruder outlet temperature of 260 ° C. Supplied.

The polymethyl methacrylate resin, the alicyclic olefin polymer, and the ethylene-vinyl acetate copolymer as an adhesive are each discharged from a multi-manifold die at 260 ° C. in a molten state, and are cooled to 130 ° C. Cast, and then passed through a cooling roll adjusted to 50 ° C., and three layers of PMMA layer (20 μm) / adhesive layer (4 μm) / COP layer (32 μm) / adhesive layer (4 μm) / PMMA layer (20 μm) A protective film 1 having a configuration (excluding the adhesive layer) and having a width of 600 mm and a thickness of 80 μm was obtained by coextrusion molding.
The refractive index of the PMMA layer at a wavelength of 380 nm was 1.512, and the refractive index at a wavelength of 780 nm was 1.488. The COP layer had a refractive index of 1.555 at a wavelength of 380 nm, and a refractive index of 1.529 at a wavelength of 780 nm.
The haze of the obtained protective film 1 was 0.1% or less, and the total light transmittance was 93%.

(Preparation of anti-glare protective film 1 <addition of anti-glare layer>)
12 parts of polystyrene particles having an average particle size of 3.5 μm, 5 parts of benzophenone photopolymerization initiator, 2.5 parts of thixotropic agent (mica) per 100 parts of acrylic urethane UV curable resin (urethane acrylate monomer) Is applied to the upper surface of the protective film 1 and dried at 120 ° C. for 5 minutes, followed by curing by ultraviolet irradiation to obtain a coating film thickness. Produced the anti-glare protective film 1 having an anti-glare layer on the surface of the fine concavo-convex structure of 7 μm.

Production Example 2
(Preparation of anti-glare protective film 2)
A protective film 2 was obtained in the same manner as in Production Example 1 except that polycarbonate resin (water absorption rate 0.2%, hereinafter sometimes referred to as “PC”) was used instead of COP. The refractive index of each of the PC layers at a wavelength of 380 nm was 1.608, and the refractive index at a wavelength of 780 nm was 1.556. The haze of the obtained protective film 2 was 0.1% or less, and the total light transmittance was 90%.
Using this protective film 2, an antiglare layer was added in the same manner as in Production Example 1 to obtain an antiglare protective film 2.

Example 1
A corona discharge treatment was performed on one side of a 100 μm-thick unstretched film made of an alicyclic olefin polymer (ring-opening polymer hydrogenated norbornene monomer; glass transition temperature 136 ° C.) using a high frequency transmitter. The film 1B having a surface tension of 0.055 N / m was obtained. The haze of this film 1B was 0.1% or less, and the total light transmittance was 92%.

  An acrylic adhesive is applied to both sides of the polarizer P, and the surface of the antiglare protective film 1 on which the antiglare layer is not formed and the corona discharge treated surface of the film 1B are overlapped toward the polarizer P, and roll to roll The laminated polarizing plate 1 was obtained by the method. The evaluation results for the obtained polarizing plate 1 are shown in Table 1.

Comparative Example 1
A polarizing plate 2 was obtained in the same manner as in Example 1 except that the antiglare protective film 2 was used instead of the antiglare protective film 1. The evaluation results for the obtained polarizing plate 2 are shown in Table 1.

<Pencil hardness>
Except for changing the load to 500 g, according to JIS K5600-5-4, the surface of the protective film (the surface in contact with the antiglare film) was scratched by about 5 mm with a 4H pencil, and the degree of damage was confirmed.
○: No damage was found in any part.
X: Scratched or more in one place.

<Observation of interference fringes>
An antiglare protective film is placed on a black cloth that does not transmit light, such as a dark curtain, and illuminated with a three-wavelength fluorescent lamp (National: FL20SS / ENW / 18), the surface of the antiglare protective film is visually observed, Evaluation was made according to the following criteria.
A: Interference fringes are not visible.
○: Interference fringes are slightly visible.
Δ: Interference fringes are conspicuous.
X: Interference fringes are conspicuous and glare occurs.

<Visibility>
The liquid crystal display panel is removed from a commercially available liquid crystal television (manufactured by Sharp Corporation, LC-13C5-S), and the viewer-side polarizing plate is peeled off from the liquid crystal cell from the liquid crystal display panel, and obtained in this example or the comparative example instead. The polarizing plate was attached to the liquid crystal cell so that the antiglare protective film was on the viewer side, the liquid crystal television was reassembled, and the display quality of the liquid crystal television was evaluated according to the following criteria.
○: The operator does not feel uncomfortable even when used for a long time (for example, about 1 to 2 hours).
X: An operator feels uncomfortable after long use.

<Color reproducibility>
The reassembled liquid crystal television was installed in an environment with an ambient brightness of 500 lux, and when the screen display was black, the display screen was visually observed and evaluated according to the following criteria.
○: Display screen color is black ×: Display screen color is blue

<Evaluation of reflection>
A polarizing plate is installed in a room having a brightness of 1000 lux, the surface on which the antiglare layer is formed is placed on top, and reflection of reflected light is visually evaluated by the fluorescent lamp contour reflected on the surface.
○: The contour is not visible △: The contour is slightly visible ×: The contour is clearly visible

Claims (8)

A refractive index n _i (λ) at a wavelength λ in a wavelength range of 380 nm to 780 nm of the i-th thermoplastic resin layer, in which k thermoplastic resin layers (k is an integer of 2 or more) are laminated, The refractive index n _{i + 1} (λ) at a wavelength λ in the range of 380 nm to 780 nm of the ( _{i + 1} ) th thermoplastic resin layer is represented by the formula [1] (where i represents an integer of 1 to k−1). Protective layer A,
A polarizer and a protective layer B are laminated in at least this order.
A polarizing plate having a haze of 10 to 60%.
| N _i (λ) −n _{i + 1} (λ) | ≦ 0.05 Formula [1] The polarizing plate according to claim 1, wherein the protective layer A has an absolute value of a photoelastic coefficient of 10 × 10 ⁻¹² Pa ⁻¹ or less.   The polarizing plate for liquid crystal displays according to claim 1 or 2, wherein an antiglare layer is laminated directly or via another layer on the surface of the protective layer A far from the polarizer.   The polarizing plate for a liquid crystal display according to any one of claims 1 to 3, wherein an antiglare layer and an antireflection layer are laminated directly or via another layer on the surface of the protective layer A far from the polarizer. .   The protective layer A is a polarizing plate for liquid crystal display according to any one of claims 1 to 4, comprising an ultraviolet absorber.   The polarizing plate for liquid crystal display according to any one of claims 1 to 5, wherein the surface of the protective layer A far from the polarizer has an uneven shape.   The polarizing plate according to any one of claims 1 to 6, further comprising a layer including a region where the refractive index is discontinuous on the surface of the protective layer A far from the polarizer, directly or via another layer. A liquid crystal display provided with the polarizing plate in any one of Claims 1-7.

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