JP2009300611A - Polarizing plate and liquid crystal panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate that has a high handling property, is easily manufactured, and has a condensing function. <P>SOLUTION: The polarizing plate includes a polarizer 30 and a first protective film 31 stacked on one main surface of the polarizer, and the average refractive index of the first protective film is ≥1.58. In viewpoint for suppressing coloring of a screen associated with condensing, the haze of the first protective film is preferably ≥2.0%. A light diffusion layer is preferably disposed between the polarizer and the first protective film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polarizing plate in which a polarizer and at least one protective film are laminated. Furthermore, this invention relates to the liquid crystal panel using the said polarizing plate, and its manufacturing method. The present invention also relates to a liquid crystal display device including the liquid crystal panel.

  Conventionally, from the viewpoint of improving the visibility of a liquid crystal display device, in order to efficiently make light emitted from a light source incident on a liquid crystal cell or the like, the emitted light is emitted by a condensing sheet having a surface uneven shape such as a prism sheet. A technique for condensing light in the front direction and improving luminance is generally used (see, for example, Patent Document 1).

  However, since the light collecting sheet made of a film having a surface irregularity shape described above has poor handling properties, the sheet tends to be easily damaged at the stage of manufacturing the sheet or at the stage of incorporation into the image display device. Further, when incorporated in an image display device, moire may occur due to non-uniform air gaps with other members.

WO94 / 09974 International Publication Pamphlet

  An object of this invention is to provide the polarizing plate which is excellent in handling property and has a condensing function. Furthermore, it aims at providing the liquid crystal panel using the polarizing plate which has the said condensing function, its manufacturing method, and a liquid crystal display device.

  As a result of intensive studies in view of the above-mentioned viewpoints, the present inventors have used a film having a predetermined optical characteristic as a protective film for a polarizer, and thus has a condensing characteristic comparable to that of a condensing element due to a surface uneven shape such as a prism sheet. It has been found that a polarizing plate having excellent handling properties can be obtained. That is, this invention relates to the polarizing plate which has a polarizer and the 1st protective film laminated | stacked on the one main surface of this polarizer. The first protective film has an average refractive index of 1.58 or more. By increasing the average refractive index of the first protective film, light incident in an oblique direction due to a difference in refractive index at the film interface can be directed in the front direction.

  In the polarizing plate of the present invention, the first protective film preferably has a haze of 2.0% or more. Moreover, it is also a preferable structure to have a light-diffusion layer between the polarizer and the first protective film. The light diffusion layer preferably has a haze of 20% or more. As described above, the first protective film having haze and / or the light diffusion layer can suppress light from being diffused and the collected light from being colored in a rainbow pattern.

  The polarizing plate of this invention can employ | adopt the form with which the 2nd protective film was laminated | stacked on the main surface on the opposite side to where the 1st protective film of the said polarizer was laminated | stacked. In such an embodiment, the average refractive index of the second protective film is preferably 1.55 or less. While the average refractive index of the first protective film is 1.58 or more, the second protective film is 1.55 or less, so that the light collected by the first protective film is changed in its incident direction. It can be incident on the liquid crystal display device without greatly changing.

  Furthermore, in the polarizing plate of this invention, it is preferable that the haze of the said 2nd protective film is 2.0% or less. By reducing the haze of the second protective film, it is possible to suppress the cancellation (depolarization) of the polarization state due to scattering and obtain an image display with high contrast.

  In the polarizing plate of the present invention, the first protective film is preferably a polyester film.

  Furthermore, in the polarizing plate of the present invention, it is preferable that the first protective film has an easy-adhesion layer formed on the surface of the first protective film on the side laminated with the polarizer. Thus, by having an easily bonding layer, adhesiveness with a polarizer can be improved.

  The present invention also relates to a liquid crystal panel using the polarizing plate. In the liquid crystal panel of the present invention, the polarizing plate is provided on at least one main surface of the liquid crystal cell, and the main surface on the opposite side to the first protective film of the polarizing plate is opposed to the liquid crystal cell. It is preferable to laminate them.

  Furthermore, the present invention relates to a method for manufacturing the liquid crystal panel. In a preferred embodiment of the method for producing a liquid crystal panel of the present invention, a roll original fabric preparation step of preparing a long sheet of the polarizing plate as a roll original fabric, a sheet product is fed out from the roll original fabric, and a cutting means is used. A cutting step of cutting the polarizing plate into a predetermined size, and a bonding step of bonding the polarizing plate to the liquid crystal cell through the adhesive layer after the cutting step.

  Furthermore, the present invention relates to a liquid crystal display device comprising the liquid crystal panel and a light source unit. In the liquid crystal display device of the present invention, it is preferable that a light source unit is provided on the side of the liquid crystal panel where the polarizing plate is disposed.

[Outline of configuration of polarizing plate]
A schematic sectional view of the polarizing plate of the present invention is shown in FIG. The polarizing plate of the present invention has the first protective film 31 on one main surface of the polarizer 30, but the main surface of the polarizer 30 on the side where the first protective film 31 is not laminated is shown in FIG. As shown in FIG. 1B, nothing may be laminated, and as shown in FIG. 1B, a form in which the second protective film 32 is laminated may be adopted. The polarizing plate of the present invention is characterized in that the average refractive index of the first protective film is 1.58 or more.

  Hereinafter, preferred forms of the polarizer, the protective film, and the laminating means constituting the polarizing plate of the present invention will be sequentially described.

[First protective film]
(Refractive index)
Usually, a polarizing plate has a structure in which a transparent film as a protective film is provided on both main surfaces of a polarizer for the purpose of preventing damage to the polarizer and preventing deterioration of optical properties. As such a protective film, a film of triacetyl cellulose (refractive index 1.48) is widely used from the viewpoint of transparency and optical isotropy. On the other hand, in the polarizing plate of the present invention, by setting the average refractive index of the first protective film to 1.58 or more, the light incident in the oblique direction due to the refractive index difference at the film interface is directed to the front direction. Therefore, it acts as a condensing polarizing plate.

As shown in FIG. 2, the light (r1) emitted from the light source has a polar angle θ ₁ (however, the normal direction of the first protective film is used as a reference for the polar angle = 0 °). , The light is refracted at the film interface due to the difference in refractive index between air and the first protective film, and the light propagates at the polar angle θ ₂ in the first protective film. The θ ₁ and θ ₂ follow Snell's law expressed by the following formula 1 with respect to the refractive indexes of air and the first protective film, n ₁ and n ₂ , respectively.
n ₁ × sin θ ₁ = n ₂ × sin θ ₂ (Formula 1)
Since the refractive index of air n ₁ ≈1, Equation 1 above can be rewritten as Equation 2 below.
sin θ ₂ = sin θ ₁ × (1 / n ₂ ) (Formula 2)

Accordingly, by increasing the refractive index n ₂ of the first protective film, the polar angle θ _{2 in the} direction in which light propagates through the first protective film is reduced, so that light is collected in the front direction. It becomes. For example, when the refractive index of the first protective film is 1.60, when light propagating through the air at a polar angle θ ₁ = 80 ° is incident on the first protective film, the polar angle θ ₂ = 38 ° Will propagate.

  From the viewpoint of enhancing the light collecting characteristics, the average refractive index of the first protective film is preferably 1.59 or more, and more preferably 1.60 or more. The upper limit of the average refractive index is not particularly limited, but if the refractive index is excessively large, reflection at the interface increases, and the luminance may decrease when incorporated in an image display device such as a liquid crystal display device. . From this viewpoint, the average refractive index of the first protective film is preferably 1.70 or less, and more preferably 1.65 or less.

Here, the average refractive index will be described. The average refractive index is a value specific to a substance, and the value is the same whether the film is optically isotropic or optically anisotropic. When the film is optically isotropic, the refractive index value in each direction of the film is equal to the average refractive index. On the other hand, when the film has optical anisotropy, the average refractive index is expressed as an average value of refractive indexes in each direction. That is, when the refractive index in the slow axis direction in the film plane is nx, the refractive index in the fast axis direction in the film plane is ny, and the refractive index in the film thickness direction is nz, the average refractive index n _ave = (nx + ny + nz). ) / 3.

(Haze)
In the polarizing plate of the present invention, the haze of the first protective film is preferably 2.0% or more, and more preferably 3.0% or more. When the haze of the first protective film is excessively small, even if light having a high average refractive index is used as the first protective film and the light is condensed in the front direction, the light is a polarizer or the first protective film Due to the difference in refractive index when entering the medium such as adhesive or pressure-sensitive adhesive existing between the film and the polarizer, it propagates again in an oblique direction (a direction where the polar angle is large), thereby obtaining sufficient light collecting characteristics. It may not be possible. On the other hand, since the first protective film has an appropriate haze, light is appropriately scattered in the first protective film, and the adhesive present between the polarizer or the first protective film and the polarizer. It is possible to suppress the light collected by the difference in refractive index from the medium such as the agent or the adhesive from being dispersed again in the direction of a large polar angle.

  In addition, the upper limit of the haze of the first protective film is not particularly limited. However, if the haze is excessively high, the liquid crystal panel includes a brightness enhancement film, so that the depolarization is increased and the contrast is lowered. May occur. From this viewpoint, the haze of the first protective film is preferably 50% or less, and more preferably 30% or less.

(Birefringence characteristics)
When the polarizing plate of the present invention is used in a liquid crystal panel to be described later, the main surface opposite to the side where the first protective film of the polarizing plate is laminated faces the liquid crystal cell from the viewpoint of acting as a condensing polarizing plate. Are arranged as follows. That is, the first protective film 31 is disposed on the surface of the polarizer 30 that does not face the liquid crystal cell. For this reason, even if the first protective film 11 has birefringence, the birefringence does not directly affect the display characteristics of the liquid crystal panel. Sex is not always necessary. From such a viewpoint, for example, even a film that does not necessarily have high birefringence uniformity, such as a commercially available biaxially stretched polyester (polyethylene terephthalate) film film, can be used.

  On the other hand, when a film having a large retardation value represented by the product of birefringence and thickness is used as the first protective film, the liquid crystal display device may cause rainbow pattern coloring due to interference. From the viewpoint of suppressing such coloring, the slow axis direction of the first protective film (the direction in which the refractive index in the film plane becomes maximum) and the absorption axis direction of the polarizer are substantially parallel or substantially orthogonal. It is preferable to arrange in such a manner. Note that “substantially parallel” and “substantially orthogonal” not only mean that the angle between the two is exactly 0 ° or 90 °, but also means that the angle is within ± 10 °, preferably ± 5 °.

  In addition, when the slow axis direction of the first protective film and the absorption axis direction of the polarizing plate are out of parallel or orthogonal, a rainbow pattern may be colored. It can be eliminated by setting the haze value of the first protective film within a predetermined range or disposing a light diffusion layer as described later. In addition, in a commercially available biaxially stretched polyester film or the like, the bowing phenomenon during stretching (the slow axis direction becomes nonuniform in the width direction) occurs, In addition, since variations in the slow axis direction between film products (between lots) occur, the arrangement direction of the slow axis direction and the absorption axis direction of the polarizer may not always be uniform. Also from this viewpoint, it is useful to prevent the coloring of the rainbow pattern by giving haze to the first protective film and arranging the light diffusion layer.

(material)
The material of the 1st protective film in the polarizing plate of this invention will not be restrict | limited especially if the said refractive index range is satisfied, Various polymer materials etc. can be used. Examples thereof include polyester resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polystyrene resin and the like. Especially, it is preferable to use the polyester film which has polyester as a main component from a viewpoint which makes a refractive index and a haze into the said range. Polyester has a high refractive index and semi-crystallinity. Therefore, the degree of crystallinity is increased by allowing crystallization to proceed by heating or the like, and the haze can be in a desired range. Furthermore, since the crystal part generally has a higher refractive index than the amorphous part, the average refractive index of the film can be increased by increasing the crystallinity.

  Examples of the polyester include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and diphenylcarboxylic acid. Acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalate Acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, Die -Dicarboxylic acids such as acid, sebacic acid, suberic acid, dodecadicarboxylic acid, ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, decamethylene Glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) A homopolymer obtained by polycondensing one kind of diol such as sulfone, a copolymer obtained by polycondensing one kind or more of dicarboxylic acid and two or more kinds of diol, or two or more kinds of dicarboxylic acid and one or more kinds Copolymers obtained by polycondensation of diols, and homopolymers thereof The or copolymer can include any of the polyester resin of two or more blend formed by blending resin. Of these, polyethylene terephthalate resin is preferably used.

  The polyester film is obtained by, for example, a method of forming the film by melt-extruding the above-described polyester resin into a film and cooling and solidifying with a casting drum. As the polyester film in the polarizing plate of the present invention, any of an unstretched film and a stretched film can be used.

  When the polyester film is a stretched film, the stretching method is not particularly limited, and a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse sequential biaxial stretching method, a longitudinal and transverse simultaneous biaxial stretching method, and the like can be employed. As the stretching means, any suitable stretching machine such as a roll stretching machine, a tenter stretching machine, a pantograph type or a linear motor type biaxial stretching machine can be used.

(Thickness)
The thickness of the first protective film is preferably 5 to 500 μm, more preferably 5 to 200 μm, and still more preferably 10 to 150 μm. If the thickness is smaller than the above range, the film is likely to break, and there may be a problem in strength when applied to a polarizing plate, the moisture barrier property becomes insufficient, and the durability of the polarizer may be inferior. When the thickness is larger than the above range, the flexibility of the film may be lacked, handling properties may be lowered, and production of the film may be difficult.

(Easily adhesive layer)
As will be described later, the first protective film is laminated via a polarizer and an adhesive or the like. However, a high refractive index polymer such as polyester has lower adhesion to the polarizer than a cellulose resin. Tend. Therefore, in the polarizing plate of this invention, it is preferable that the easily bonding layer is formed in the surface by which the polarizer of the said 1st protective film is laminated | stacked.

  The easy-adhesion layer is formed of a hydrophilic cellulose derivative, a polyvinyl alcohol compound, a hydrophilic polyester compound, a polyvinyl compound, a (meth) acrylic acid compound, an epoxy resin, a polyurethane compound, a natural polymer compound, or the like. Can be mentioned. Among these, from the viewpoint of adhesiveness, a polyvinyl alcohol compound or a polyurethane compound can be suitably used.

  Furthermore, the said easily bonding layer may contain the crosslinking agent. In particular, when the easy-adhesion layer has low adhesion (adhesion) with a first protective film generally made of polyester or the like, such as a polyvinyl alcohol compound or a polyvinyl compound, the easy-adhesion layer is crosslinked. It is preferable that an agent is included. Examples of the crosslinking agent include acrylic, styrene, epoxy, phenol, phenoxy ether, phenoxy ester, melamine, and urethane crosslinking agents. Especially, from a viewpoint of improving the adhesiveness of a 1st protective film and an easily bonding layer, the crosslinking agent which has an oxazoline group, a diimide group, a hydrazine group, and an epoxy group can be used suitably.

  The easy-adhesion layer is preferably formed by applying the above compound as a solution, dispersion, or emulsion to the protective film. In application, it is preferably used as an aqueous coating liquid from the viewpoint of preventing environmental pollution and obtaining explosion-proof properties. In addition, a surfactant can be blended from the viewpoint of promoting the wetting of the aqueous coating liquid on the protective film and the stability of the coating liquid. The appropriate blending amount of the surfactant in the coating liquid varies depending on the type of the surfactant, but can be appropriately prepared so as to have sufficient adhesiveness with the polarizer. For example, about 1 to 10 parts may be contained per 100 parts by weight of the solid content of the aqueous coating liquid. An antistatic agent, a colorant, an ultraviolet absorber, a crosslinking agent, a pigment, an organic filler, and an inorganic filler may be further added to the coating liquid.

  Moreover, when apply | coating a coating liquid to a protective film, a corona treatment, a plasma treatment, etc. can also be given to the film surface beforehand from a viewpoint of improving applicability | paintability.

  The coating amount of the coating liquid is preferably adjusted so that the thickness of the easy-adhesion layer is about 0.001 to 10 μm, further about 0.001 to 5 μm, and particularly about 0.001 to 1 μm. When the thickness of the coating layer is excessively small, the adhesive force with the polarizer may be insufficient, and when the thickness is excessively large, blocking may occur.

  As a coating method, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a roll brush method, a spray coating method, an air knife coating method, an impregnation method, and a curtain coating method can be provided. These may be used alone or in combination. The coating liquid applied on the protective film is dried on heating or the like to form an easy-adhesion layer on the film.

[Polarizer]
A polarizer refers to a film that can be converted from natural light or polarized light into arbitrary polarized light. Any appropriate polarizer may be adopted as the polarizer used in the present invention, but a polarizer that converts natural light or polarized light into linearly polarized light is preferably used.

  In the polarizing plate of this invention, arbitrary appropriate things can be employ | adopted as a polarizer according to the objective. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And a polyene-based oriented film such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product or a polyvinyl chloride dehydrochlorinated product. Further, a guest / host type O-type polarizer in which a liquid crystalline composition containing a dichroic substance and a liquid crystalline compound disclosed in US Pat. No. 5,523,863 is aligned in a certain direction, US Pat. An E-type polarizer or the like in which lyotropic liquid crystals disclosed in US Pat. No. 6,049,428 are aligned in a certain direction can also be used.

  Among such polarizers, from the viewpoint of having a high degree of polarization and adhesiveness with the protective film on which the easy-adhesion layer is formed, a polarizer made of a polyvinyl alcohol film containing iodine is preferably used. It is done. Polyvinyl alcohol or a derivative thereof is used as a material for the polyvinyl alcohol film applied to the polarizer. Derivatives of polyvinyl alcohol include polyvinyl formal, polyvinyl acetal, and the like, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and their alkyl esters and acrylamide. Things. Polyvinyl alcohol having a polymerization degree of about 1000 to 10000 and a saponification degree of about 80 to 100 mol% is generally used.

  The polyvinyl alcohol film may contain an additive such as a plasticizer. Examples of the plasticizer include polyols and condensates thereof, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The amount of the plasticizer used is not particularly limited, but is preferably 20% by weight or less in the polyvinyl alcohol film.

  The polyvinyl alcohol film (unstretched film) is at least subjected to uniaxial stretching treatment and iodine dyeing treatment according to a conventional method. Furthermore, boric acid treatment and iodine ion treatment can be performed. Moreover, the polyvinyl alcohol film (stretched film) subjected to the treatment is dried according to a conventional method to form a polarizer.

  The stretching method in the uniaxial stretching treatment is not particularly limited, and either a wet stretching method or a dry stretching method can be employed. Examples of the stretching means of the dry stretching method include an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. Stretching can also be performed in multiple stages. In the stretching means, the unstretched film is usually heated. Usually, an unstretched film having a thickness of about 30 to 150 μm is used. The stretch ratio of the stretched film can be appropriately set according to the purpose, but the stretch ratio (total stretch ratio) is about 2 to 8 times, preferably 3 to 6.5 times, more preferably 3.5 to 6 times. Is desirable. The thickness of the stretched film is preferably about 5 to 40 μm.

  The polarizer can also contain zinc. Inclusion of zinc in the polarizer is preferable in terms of suppressing hue deterioration under a heating environment. The zinc content in the polarizer is preferably adjusted so that the zinc element is contained in the polarizer in an amount of 0.002 to 2% by weight. Furthermore, it is preferable to adjust to 0.01 to 1 weight%. When the zinc content in the polarizer is within the above range, the durability improving effect is good, which is preferable for suppressing the deterioration of the hue.

  A zinc salt solution is used for the zinc impregnation treatment. As the zinc salt, an inorganic salt compound of an aqueous solution such as zinc halides such as zinc chloride and zinc iodide, zinc sulfate, and zinc acetate is preferable. Among these, zinc sulfate is preferable because the retention rate of zinc in the polarizer can be increased. Various zinc complex compounds can be used for the zinc impregnation treatment. The concentration of zinc ions in the zinc salt aqueous solution is about 0.1 to 10% by weight, preferably 0.3 to 7% by weight. The zinc salt solution is preferably an aqueous solution containing potassium ions and iodine ions with potassium iodide or the like because zinc ions are easily impregnated. The potassium iodide concentration in the zinc salt solution is preferably about 0.5 to 10% by weight, more preferably 1 to 8% by weight.

[Lamination of first protective film and polarizer]
The method for laminating the polarizer and the first protective film is not particularly limited, but from the viewpoint of workability and utilization efficiency of light, it is desirable to laminate without any air gap through an adhesive layer or an adhesive layer. When using an adhesive layer or a pressure-sensitive adhesive layer, the type is not particularly limited, and various types can be used.

(Adhesive layer)
From the viewpoint of enhancing the adhesion between the polarizer and the protective film, an adhesive layer is suitably used for laminating them. Examples of the adhesive that forms the adhesive layer include acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy systems, fluorine systems, and natural rubber systems. Those having a base polymer of a rubber-based polymer such as synthetic rubber can be appropriately selected and used. In particular, a water-based adhesive is preferably used for laminating the polarizer and the optically isotropic film. Among them, those mainly composed of polyvinyl alcohol resin are used.

  Examples of the polyvinyl alcohol resin used for the adhesive include a polyvinyl alcohol resin and a polyvinyl alcohol resin having an acetoacetyl group. A polyvinyl alcohol resin having an acetoacetyl group is a polyvinyl alcohol-based adhesive having a highly reactive functional group, and is preferable because durability of the polarizing plate is improved.

  Moreover, it is preferable that an adhesive agent contains a crosslinking agent. Examples of the cross-linking agent include alkylene diamines having two alkylene groups and two amino groups such as ethylene diamine, triethylene diamine and hexamethylene diamine; tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane tolylene diisocyanate adduct, triphenyl Isocyanates such as methane triisocyanate, methylene bis (4-phenylmethane triisocyanate, isophorone diisocyanate and their ketoxime block product or phenol block product; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether Epoxies such as diglycidylaniline and diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde and butyraldehyde; glyoxal, malondialdehyde, succinaldehyde, glutardialdehyde, maleindialdehyde, phthaldialdehyde Dialdehydes such as: methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetoguanamine, condensates of benzoguanamine and formaldehyde, and the like; further sodium, potassium, magnesium, calcium, Examples thereof include salts of divalent metals such as aluminum, iron, nickel, or trivalent metals and oxides thereof, among which amino-formaldehyde Fats and dialdehydes are preferred, amino-formaldehyde resins are preferably compounds having a methylol group, and dialdehydes are preferably glyoxal, especially methylol melamine, which is a compound having a methylol group. .

  Furthermore, from the viewpoint of suppressing the occurrence of uneven defects (knics), it is also preferable to include a metal colloid in the adhesive. Examples of such metal colloids include alumina colloid, silica colloid, zirconia colloid, titania colloid and tin oxide colloid. Specifically, those described in JP-A-2008-15383 can be suitably used.

  It is preferable to apply the adhesive so that the thickness of the adhesive layer after drying is about 10 to 300 nm. The thickness of the adhesive layer is more preferably from 10 to 200 nm, and even more preferably from 20 to 150 nm, from the viewpoint of obtaining a uniform in-plane thickness and sufficient adhesive strength. Attaching the pressure-sensitive adhesive layer or adhesive layer to the film can be performed by an appropriate method.

  The pressure-sensitive adhesive layer and the adhesive layer can also be provided on one side or both sides of the film as an overlapping layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as adhesive layers, such as a different composition, a kind, and thickness, in the front and back of a film.

  Further, the protective film may be subjected to a surface modification treatment such as hydrophilization for the purpose of improving the adhesiveness before attaching the adhesive or the pressure-sensitive adhesive. Specific examples of the treatment include corona treatment, plasma treatment, primer treatment, and saponification treatment.

(Light diffusion layer)
In the polarizing plate of the present invention, as shown in FIG. 3, a light diffusion layer is provided between the polarizer 30 and the first protective film 31 from the viewpoint of preventing the condensed light from being colored in a rainbow pattern. It is also preferable to arrange 20. As such a light diffusion layer, a layer having small backscattering is preferably used. Among these, the use of a diffusion adhesive layer as the light diffusion layer is a preferable configuration because the polarizer 30 and the first protective film 31 can be laminated without air gaps in addition to the function as the light diffusion layer. . As such a diffusion pressure-sensitive adhesive layer, a material in which particles having different refractive indexes are mixed with a pressure-sensitive adhesive is effectively used. As such particles, for example, fine particle dispersion type diffusion materials as disclosed in JP 2000-347006 A and JP 2000-347007 A are preferably used.

  The haze of the light diffusion layer is preferably 20% or more, and more preferably 30% or more. By setting the haze in the above range, the screen can be prevented from being colored in a rainbow pattern. Further, the haze of the light diffusion layer is preferably 88% or less, and more preferably 75% or less. When the haze is excessively high, depolarization by the light diffusion layer becomes large, and thus the contrast tends to decrease in a configuration in which the liquid crystal panel includes a brightness enhancement film.

[Second protective film]
In the polarizing plate of the present invention, in addition to the first protective film 31 and the polarizer 30, as shown in FIG. 1B, the main surface on the opposite side to the first protective film laminated. It is also possible to adopt a form in which the second protective film 32 is laminated.

(Birefringence)
As described above, when the polarizing plate of the present invention is used for a liquid crystal panel, the main surface of the polarizing plate opposite to the side where the first protective film 31 is laminated, that is, the polarizing plate has the second protective film 32. When it has, it arrange | positions so that this 2nd protective film 32 may oppose a liquid crystal cell. For this reason, the second protective film is disposed between the polarizer and the liquid crystal cell, and the birefringence can affect the display characteristics of the liquid crystal panel. From this point of view, the second protective film is substantially optically isotropic having no birefringence, or even if it has birefringence, its retardation value or optical axis direction. It is preferable to use one having excellent in-plane uniformity. In addition, as the second protective film, a retardation plate (optical compensation layer) described later can be used.

(Refractive index)
In the polarizing plate of this invention, it is preferable that the average refractive index of a 2nd protective film is 1.55 or less. If the average refractive index of the second protective film is excessively high, the ratio of the light transmitted through the liquid crystal cell from the viewing side and reaching the polarizing plate to the liquid crystal cell is reflected by the second protective film. For this reason, color floating (black floating) may occur during black display due to the influence of reflected light. In particular, when applied to a liquid crystal panel in which circularly polarized light is incident on a liquid crystal cell, such as a transflective mode liquid crystal display device, the effect of color floating due to reflection of external light tends to be significant. The average refractive index of the second protective film is more preferably 1.54 or less, and further preferably 1.53 or less. Moreover, it is preferable to provide a difference in the average refractive index of the first protective film and the second protective film from the viewpoint of obtaining higher light collection characteristics. The difference in average refractive index between the two is preferably 0.05 or more, more preferably 0.07 or more, further preferably 0.09 or more, and particularly preferably 0.10 or more. .

(Haze)
The haze of the second protective film is preferably 2% or less, and more preferably 1% or less. When the haze of the second protective film is high, the polarization state of light converted into a constant polarization state by a polarizer due to scattering changes non-uniformly (depolarization), and the polarizing plate of the present invention is used for a liquid crystal display device. The contrast may decrease.

(material)
Although the material of the 2nd protective film in the polarizing plate of this invention is not restrict | limited in particular, As above-mentioned, the transparent polymer with a uniform optical characteristic can be used suitably. In particular, an amorphous polymer is preferably used from the viewpoint of transparency (low haze). From this viewpoint, it is preferable to use at least one selected from a cellulose resin, a cyclic polyolefin resin, and a (meth) acrylic resin as the second protective film.

  Cellulose resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, dipropionyl cellulose and the like. Among these, triacetyl cellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available products of triacetyl cellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, “UZ-” manufactured by Fuji Film. TAC ”,“ KC Series ”manufactured by Konica Minolta, and the like.

  Specific examples of the cyclic polyolefin resin are preferably norbornene resins. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And graft polymers obtained by modifying them with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as the cyclic polyolefin resin. Specific examples include trade names “ZEONEX” and “ZEONOR” manufactured by ZEON Corporation, “ARTON” manufactured by JSR, “TOPAS” manufactured by TICONA, and “APEL” manufactured by Mitsui Chemicals.

  The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. When Tg is 115 ° C. or higher, the polarizing plate can be excellent in durability. Although the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or lower from the viewpoint of moldability and the like. From the (meth) acrylic resin, a film having in-plane retardation (Re) and thickness direction retardation (Rth) of almost zero can be obtained.

  As the (meth) acrylic resin, any appropriate (meth) acrylic resin can be adopted as long as the effects of the present invention are not impaired. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), a polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferably, poly (meth) acrylate C1-6 alkyl such as poly (meth) acrylate methyl is used. More preferred is a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

  Specific examples of the (meth) acrylic resin include, for example, Mitsubishi Rayon Acrypet VH and Acrypet VRL20A, and a (meth) acrylic resin having a ring structure in the molecule described in JP-A-2004-70296, molecule. Examples thereof include high Tg (meth) acrylic resin systems obtained by internal crosslinking and intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure can also be used. Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. No. 146084 and the like.

  As the (meth) acrylic resin, an acrylic resin having a structural unit of unsaturated carboxylic acid alkyl ester and a structural unit of glutaric anhydride can be used. Examples of the acrylic resin include Japanese Patent Application Laid-Open Nos. 2004-70290, 2004-70296, 2004-163924, 2004-292812, 2005-314534, and 2006. No. 131898, JP 2006-206881 A, JP 2006-265532 A, JP 2006-283013 A, JP 2006-299005 A, JP 2006-335902 A, and the like. It is done.

  In addition, as the (meth) acrylic resin, a thermoplastic resin having a glutarimide unit, a (meth) acrylic ester unit, and an aromatic vinyl unit can be used. Examples of the thermoplastic resin include JP 2006-309033 A, JP 2006-317560 A, JP 2006-328329 A, JP 2006-328334 A, JP 2006-337491 A, and JP 2006. -337492, JP-A-2006-337493, JP-A-2006-337569, and the like.

  Moreover, as a transparent protective film excellent in optical isotropy, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007), for example, (A) It has a substituted and / or unsubstituted imide group in a side chain. A resin composition containing a thermoplastic resin and (B) a thermoplastic resin having a substituted and / or unsubstituted phenyl and nitrile group in the side chain can also be suitably used.

(Phase difference value)
The second protective film is optically isotropic having substantially no birefringence as described above, or even in the case of having birefringence, the phase difference value or the surface in the direction of the optical axis. Those excellent in internal uniformity are preferably used. As an optically isotropic material having substantially no birefringence, one having a front phase difference of less than 40 nm and a thickness direction retardation of less than 80 nm can be used. Thus, an unstretched film is used suitably as a protective film with small birefringence.

  The front phase difference Re is represented by Re = (nx−ny) × d. The thickness direction retardation Rth is represented by Rth = (nx−nz) × d. The Nz coefficient is represented by Nz = (nx−nz) / (nx−ny). [However, the refractive indexes in the slow axis direction, the fast axis direction, and the thickness direction of the film are nx, ny, and nz, respectively, and d (nm) is the thickness of the film. The slow axis direction is the direction that maximizes the refractive index in the film plane. ].

  On the other hand, by using a film having a front retardation of 40 nm or more and / or a retardation having a thickness direction retardation of 80 nm or more as the second protective film, the function of the retardation plate can also be used. In that case, the front retardation and the thickness direction retardation can be appropriately adjusted to values required for optical compensation as a retardation plate. As such a retardation plate, a stretched film can be suitably used.

  The retardation plate has a relationship of nx = ny> nz, nx> ny> nz, nx> ny = nz, nx> nz> ny, nz = nx> ny, nz> nx> ny, nz> nx = ny. Those satisfying the above are selected and used according to various applications. Note that ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same.

(Thickness)
The thickness of the second protective film is preferably 5 to 500 μm, more preferably 5 to 200 μm, and still more preferably 10 to 150 μm. If the thickness is smaller than the above range, the film is likely to break, and there may be a problem in strength when applied to a polarizing plate, the moisture barrier property becomes insufficient, and the durability of the polarizer may be inferior. When the thickness is larger than the above range, the flexibility of the film may be lacked, handling properties may be lowered, and production of the film may be difficult.

[Lamination of second protective film and polarizer]
The method for laminating the polarizer and the second protective film is not particularly limited, but from the viewpoint of workability and utilization efficiency of light, it is desirable to laminate without any air gap through an adhesive layer or an adhesive layer. When using an adhesive layer or a pressure-sensitive adhesive layer, the type is not particularly limited, and various types can be used. For example, what was mentioned above as an adhesive layer used for lamination | stacking of a 1st protective film and a polarizer can be employ | adopted suitably.

[Other optical layers]
The polarizing plate of the present invention may have other optical layers in addition to the polarizer, the first protective film, the second protective film, and the adhesive layer and the pressure-sensitive adhesive layer for laminating them. it can. Examples of such an optical layer include a surface treatment layer, a brightness enhancement film, a reflection layer, and a retardation film.

(Adhesive layer)
The polarizing plate of the present invention can be provided with a pressure-sensitive adhesive layer for laminating each optical layer or adhering to other members such as a liquid crystal cell. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, a silicone-based polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based or rubber-based polymer is appropriately used as a base polymer. It can be selected and used. In particular, those having excellent optical transparency, such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and having excellent weather resistance, heat resistance and the like can be preferably used.

  The pressure-sensitive adhesive layer can be provided on one side or both sides of a laminated optical film or other optical layers as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as adhesive layers, such as a different composition, a kind, and thickness, in the front and back of a polarizing plate or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

(Release film)
The exposed surface of the pressure-sensitive adhesive layer is preferably temporarily covered with a release film (separator) for the purpose of preventing contamination until it is practically used. Thereby, it can prevent contacting an adhesive layer in the usual handling state. As the release film, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, or the like, if necessary In addition, an appropriate one according to the prior art, such as those coated with an appropriate release agent such as a long-chain alkyl, fluorine-based, or molybdenum sulfide, can be used.

  In the present invention, the polarizer, the protective film, the adhesive, the pressure-sensitive adhesive layer, the other optical layer, and the like that form the polarizing plate are, for example, salicylic acid ester compounds, benzophenol compounds, and benzotriazole compounds. In addition, those having ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorber such as a cyanoacrylate compound or a nickel complex salt compound may be used.

[LCD panel]
The polarizing plate of the present invention can be preferably used for forming an image display device such as a liquid crystal display device or an organic EL display device. Among these, the polarizing plate of the present invention is preferably used for a liquid crystal display device that performs display using light from the outside of the image display cell, such as a light source unit and reflection of external light, in view of having a light collecting function. it can. In general, as shown in FIG. 4, the liquid crystal display device includes a liquid crystal panel 100 in which an optical element such as a polarizing plate is laminated on a liquid crystal cell, a light source unit 200 including a backlight, and a drive circuit and the like as necessary. It is formed by assembling.

  The formation of the liquid crystal panel is not particularly limited except that the polarizing plate according to the present invention is used, and can be based on the conventional one. As the liquid crystal cell, any type of liquid crystal cell such as VA mode, IPS mode, TN mode, STN mode, or bend alignment (π type) can be used.

  The polarizing plate of the present invention can be disposed on one side or both sides of the liquid crystal cell. When disposing the polarizing plate of the present invention on one side of the liquid crystal cell, it can be disposed on either the light source side or the viewing side of the liquid crystal cell, but from the viewpoint of exerting the light collecting characteristics of the polarizing plate, The polarizing plate of the present invention is preferably disposed on the main surface on the side where the light source unit 200 is disposed when the liquid crystal panel 100 and the light source unit 200 are assembled. Further, from the same viewpoint, as shown in FIG. 4, the main surface on the opposite side to the first protective film 31 laminated (if the second protective film 32 is laminated, the second protection The polarizing plate 1 of the present invention is preferably laminated so that the main surface on the film 32 side faces the liquid crystal cell 10. Although an arbitrary optical film can be disposed on the other main surface (viewing side) of the liquid crystal cell, it is preferable to dispose the polarizing plate 2 as shown in FIG. As the polarizing plate, the polarizing plate of the present invention or any other polarizing plate can be used.

[Liquid Crystal Display]
FIG. 4 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. This liquid crystal display device includes a liquid crystal panel 100 and a light source unit 200. The light source unit 200 includes a light source 130 and a light guide plate 120. Moreover, in another embodiment, as long as the optical member illustrated in FIG. 4 satisfies the present invention, a part of the optical member is omitted depending on the driving mode and use of the liquid crystal cell to be used. The optical member can be replaced. Further, the liquid crystal display device of the present invention may be provided with members other than those exemplified in FIG.

[Method of forming liquid crystal panel]
In forming the liquid crystal panel, in particular, as shown in FIG. 1A, the first protective film is laminated only on one main surface of the polarizer, and the protective film is laminated on the other surface of the polarizer. Even if the protective film (the first protective film and the second protective film) is laminated on both main surfaces of the polarizer as shown in FIG. In the case of this film, the stress applied to the film interface of the polarizer may be different between one main surface and the other main surface of the polarizer. That is, since the layer structure is different between the front and back of the polarizer, the external stress applied to the polarizer may be different between the front and back of the film. When there is such an external stress difference, the film tends to have a bendability. Such a film that is easily bent is difficult to be processed into an image display device in the conventional manufacturing process as described below.

(Conventional liquid crystal panel manufacturing process)
As conceptually shown in FIG. 5, the conventional manufacturing process of a liquid crystal panel is roughly divided into a manufacturing process in an optical film manufacturer and a manufacturing process in a panel processing manufacturer. First, an optical film manufacturer manufactures an optical film such as a polarizing plate as a roll material for a long (band-shaped) sheet product (# 1). Next, the raw roll is slit into a predetermined size (size according to the size of the liquid crystal cell) (# 2). Next, the slit raw material is cut to a fixed size in accordance with the size of the liquid crystal cell to be bonded, such as a liquid crystal cell (# 3). Next, an appearance inspection is performed on the sheet-like product (optical film) that has been cut into pieces (# 4). Examples of the inspection method include visual defect inspection and inspection using a known defect inspection apparatus. The defect means, for example, surface or internal dirt, scratches, a dent-like defect including a foreign object, an uneven defect, a bubble, a foreign object, or the like. Next, a finished product inspection is performed (# 5). The finished product inspection is an inspection that complies with quality standards that are more stringent than the appearance inspection. Next, the end surfaces of the four end surfaces of the sheet-like product are processed (# 6). This is performed to prevent the adhesive or the like from protruding from the end face during transportation. Next, in a clean room environment, the single sheet product is clean-wrapped (# 7). Next, packaging for transportation (transport packaging) (# 8). A sheet-like product is manufactured as described above and transported to a panel processing manufacturer.

  The panel processing manufacturer unpacks and disassembles the sheet-like product that has been transported (# 11). Next, an appearance inspection is performed in order to inspect for scratches, dirt, etc. that occur during transportation or at the time of unpacking (# 12). The sheet-like product that has been determined to be non-defective in the inspection is conveyed to the next process. Note that this appearance inspection may be omitted. The liquid crystal cell to which the single sheet product is bonded is manufactured in advance, and the liquid crystal cell is washed before the bonding step (# 13).

  Next, the single sheet product and the liquid crystal cell are bonded together (# 14). The release film is peeled off from the sheet-like product leaving the pressure-sensitive adhesive layer, and is bonded to one surface of the liquid crystal cell using the pressure-sensitive adhesive layer as a bonding surface. Further, it can be similarly bonded to the other surface of the liquid crystal cell. When bonding to both, the optical film of the same structure may be bonded to each surface of a liquid crystal cell, and the optical film of a different structure may be bonded. Next, the bonded state and defect inspection are performed (# 15). The liquid crystal panel determined to be non-defective in this inspection is transported to the mounting process and mounted on an image display device such as a liquid crystal display device (# 16). On the other hand, the liquid crystal panel determined to be defective is subjected to a rework process (# 17). The optical film is peeled from the liquid crystal cell by the rework process. An optical film is newly bonded to the reworked liquid crystal panel (# 14).

  When the conventional manufacturing process as described above is applied to a film that is easily bent, a polarizing plate is present in a roll shape (# 1), (# 2), and is stretched between transport lines. Therefore, the bending behavior is suppressed by the tension. However, when this is cut to a regular length (# 3), the tension that suppresses the bending behavior of the polarizing plate is released, so that bending occurs, and the appearance inspection (# 4) to bonding with the liquid crystal cell (# 14) ) Is difficult to handle. Furthermore, in the case of the conventional manufacturing process, in addition to the above-mentioned problem of handling due to the curvature, there is a problem that the manufacturing cost increases because it is a multi-process such as inspection and packing.

(Manufacturing method by continuous method)
The film formed in such a long roll shape is continuously bonded to the liquid crystal cell while being fed out in the presence of tension, so that the bending can be suppressed and this problem can be solved. In other words, by performing continuous cutting (# 3) and bonding to a liquid crystal cell (# 14), which were conventionally performed separately by an optical film manufacturer and a panel processing manufacturer, in one place, an appearance inspection (# 4). Finished product inspection (# 5), end face processing (# 6), clean packaging (# 7) transport packaging (# 8), packaging dismantling (# 11), appearance inspection (# 12) are not required, and curved The problem of handling due to can be solved.

  Formation of such an image display device by a continuous method uses a roll original fabric preparation step of preparing the long sheet of the polarizing plate of the present invention as a roll original fabric, a sheet product from the roll original fabric, and a cutting means. A cutting step of cutting the polarizing plate into a predetermined size, and a bonding step of bonding the polarizing plate to the liquid crystal cell through the adhesive layer after the cutting step. One example is shown below.

(Embodiment 1 by continuous method (normal cutting method))
(1) 1st roll original fabric preparation process (FIG. 6, S1)
The polarizing plate of the present invention formed into a long shape is prepared as a first roll raw material. As shown in FIG. 7A, the polarizing plate includes a first optical film 11 in which a polarizer 30 and a first protective film 31 laminated on one main surface of the polarizer are laminated, The 1 adhesive layer 14 and the 1st release film 12 are laminated | stacked. The first pressure-sensitive adhesive layer and the first release film are provided on the main surface of the optical film 11 on the side where the first protective film 31 is not laminated. In addition, the polarizing plate used as a 1st roll original fabric is not limited to the form shown to Fig.7 (a), For example, as shown to FIG.7 (b), the 1st protective film 31 of the polarizer 30 is shown. What has the 2nd protective film 32 can be used for the main surface by which side is not laminated | stacked.

(2) First cutting step (FIG. 6, S2)
Next, the first sheet product is fed out from the first roll prepared and installed, and the first optical film 11 and the first pressure-sensitive adhesive layer without cutting the first release film 12 using a cutting means. 14 is cut into a predetermined size. Thereby, the 1st optical film 11 and the 1st adhesive layer 14 can be cut | disconnected, without cut | disconnecting the 1st release film 12. FIG. Therefore, since the first optical film 11 is still formed on the first release film 12 via the first pressure-sensitive adhesive layer 14, the first optical film 11 is not curved. Examples of the cutting means include a laser device, a cutter, and other known cutting means.

(3) 1st optical film bonding process (FIG. 6, S3)
Next, after the first cutting step, the first optical film 11 from which the first release film 12 has been removed is removed via the first pressure-sensitive adhesive layer 14 while removing the first release film 12. Affix to W. Therefore, even if the 1st release film 12 is peeled, the 1st optical film 11 can be bonded together to the liquid crystal cell W in the state by which the curvature of the 1st optical film 11 was suppressed. The liquid crystal cell W is preferably preliminarily cleaned before being bonded.

  Each process of these 1st roll original fabric preparation processes, the 1st cutting process, and the 1st optical film pasting process is performed with the continuous production line. In the above series of manufacturing steps, the first optical film 11 is bonded to one main surface of the liquid crystal cell W. Below, the manufacturing process which bonds the 2nd optical film 21 on the other main surface is demonstrated.

(4) Second roll stock preparation process (FIG. 6, S4)
A long second sheet product 2 is prepared as a second roll material. The laminated structure of the second sheet product 2 includes a second optical film 21, a second pressure-sensitive adhesive layer 24, and a second release film 22, as in the case of the first optical film. In addition, as an 2nd optical film, although arbitrary optical films can be used, it is preferable that it is a polarizing plate containing a polarizer.

(5) Second cutting step (FIG. 6, S5)
Subsequently, the second sheet product is fed out from the prepared second roll raw material, and the second optical film 21 and the second optical film 21 are cut without cutting the second release film 22 as in the case of the first optical film. 2 The adhesive layer 24 is cut into a predetermined size.

(6) 2nd optical film bonding process (FIG. 6, S6)
Next, after the second cutting step, while removing the second release film 22, the second optical film 21 from which the second release film 22 has been removed is subjected to liquid crystal via the second pressure-sensitive adhesive layer 24. The first optical film 11 of the cell W is bonded to a surface different from the surface to which the first optical film 11 is bonded. Therefore, even if it peels off the 2nd release film 22, the 2nd optical film 21 can be bonded together to the liquid crystal cell W in the state by which the curve of the 2nd optical film 21 was suppressed. Thus, a liquid crystal panel in which the first optical film 11 is bonded to one surface of the liquid crystal cell W, the second optical film 21 is bonded to the other surface, and the optical films are provided on both surfaces can be manufactured.

  And each process of the 1st roll original fabric preparation process, the 1st cutting process, the 1st optical film pasting process, the 2nd roll original fabric preparation process, the 2nd cutting process, and the 2nd optical film pasting process was continued. Run on the production line.

(7) Inspection process Furthermore, it is preferable to have an inspection process (FIG. 6, S7) as a continuous process. Examples of the inspection process include an inspection process for inspecting the bonding state and an inspection process for inspecting defects after bonding, and either one of the inspections may be performed, but it is preferable to perform both inspections.

(8) Mounting process In the inspection process, the non-defective liquid crystal panel is mounted on the image display device. If a defective product is determined, a rework process is performed, a new optical film is applied, and then inspected.If a good product is determined, the process proceeds to a mounting process. Dispose of.

  In the embodiment described above, the polarizing plate of the present invention is used as the first optical film 11, but the polarizing plate of the present invention can also be used as the second optical film 21. Further, the polarizing plate of the present invention can be used for both the first optical film 11 and the second optical film 21.

  According to the manufacturing method in which the cutting from the roll material as described above and the bonding with the liquid crystal cell are continuously performed, the protective film bonded on the front and back of the polarizer is different, so that the bending easily occurs. Even when using a polarizing plate, because the polarizing plate and the liquid crystal cell can be bonded together efficiently, the productivity is excellent, and the number of steps can be reduced compared to the manufacturing process of a conventional liquid crystal panel. It is also possible to reduce production costs.

  In addition, description of the flowchart shown in FIG. 6 and said each process is an example which shows the manufacturing method of the image display panel of this invention, and has a roll original fabric preparation process, a cutting process, and a bonding process. If so, other steps may be omitted. Furthermore, you may have another process in the range of the objective of the said manufacturing method. For example, by examining the presence or absence of defects before cutting the polarizing plate to a predetermined size and adopting a method of cutting to a predetermined size so as to remove the part containing the defect, the yield of image display cells is greatly improved. In addition, it is possible to reduce the frequency of rework processing.

  The liquid crystal panel thus obtained can be suitably used for any appropriate liquid crystal display device, similarly to the conventional liquid crystal panel. In particular, the liquid crystal panel of the present invention efficiently uses light from a light source such as a backlight by using a polarizing plate having a light condensing characteristic even when a condensing element having a surface irregularity shape such as a prism sheet is not used. Also in the point which can be utilized well, it can contribute to productivity improvement and cost reduction. Applications include, for example, OA devices such as personal computer monitors, notebook computers, and copy machines, mobile phones, watches, digital cameras, personal digital assistants (PDAs), portable devices such as portable game machines, video cameras, televisions, microwave ovens, etc. Household electrical equipment, back monitor, car navigation system monitor, car audio and other in-vehicle equipment, display equipment for commercial store information monitors, security equipment such as monitoring monitors, nursing care monitors, medical monitors, etc. Nursing care / medical equipment.

  The present invention will be described below with reference to examples, but the present invention is not limited to the examples shown below. In addition, the following examples, reference examples, and comparative examples were evaluated by the following methods.

[Measurement and evaluation methods]
(Haze)
It was measured using an integrating sphere type transmittance measuring device (trade name “HM-150” manufactured by Murakami Color Research Laboratory Co., Ltd.).

(Refractive index)
Using an Atago Abbe refractometer, the refractive index at a wavelength of 589 nm was measured.

(Brightness and contrast)
In a dark room at 23 ° C., a black image and a white image were displayed on the liquid crystal display device, and each luminance (Y value of the XYZ display system) was measured by an ELDIM product name “EZ Contrast 160D”. Measurement is performed in a range of polar angle 0 ° (front direction) to 70 ° with respect to azimuth angle 0 ° (left direction of the screen), and a relative value normalized with a value at polar angle 0 ° as 1. Represents. The contrast (CR) is a ratio of black luminance to white luminance (white luminance / black luminance).

(Screen coloring)
A white image was displayed on the liquid crystal display device in a dark room at 23 ° C., and it was confirmed whether or not the rainbow pattern screen was colored when viewed from the front.

[Example 1]
(Formation of easy adhesion layer on polyester film)
A biaxially stretched polyethylene terephthalate film with a thickness of 38 μm (trade name “Diafoil T-500” manufactured by Mitsubishi Chemical Polyester Film, 4.0% haze, hereinafter referred to as “PET1”) is subjected to corona treatment, and then polyester-based water-dispersed urethane adhesive. The agent (trade name “Superflex SF210”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was applied using a coating tester equipped with a gravure roll of mesh # 200, dried at 150 ° C. for 1 minute, and then on the polyethylene terephthalate film. An easy-adhesion layer having a thickness of 0.3 μm was formed.

(Creating a polarizer)
A polyvinyl alcohol film having an average degree of polymerization of 2700 and a thickness of 75 μm was stretched and conveyed while being dyed between rolls having different peripheral speeds. First, it was immersed in a 30 ° C. water bath for 1 minute to swell the polyvinyl alcohol film and stretched 1.2 times in the conveying direction, and then a 30 ° C. potassium iodide concentration of 0.03% by weight and an iodine concentration of 0.3 By immersing in a weight% aqueous solution for 1 minute, the film was stretched 3 times in the transport direction with reference to a film (original length) that was not stretched at all while dyeing. Next, the film was stretched 6 times based on the original length in the conveying direction while being immersed in an aqueous solution having a boric acid concentration of 4% by weight and a potassium iodide concentration of 5% by weight for 30 seconds. Next, the obtained stretched film was dried at 70 ° C. for 2 minutes to obtain a polarizer. The polarizer had a thickness of 30 μm and a moisture content of 14.3% by weight.

(Preparation of adhesive)
Polyvinyl alcohol resin having an acetoacetyl group (average polymerization degree 1200, saponification degree 98.5% mol%, acetoacetyl group modification degree 5 mol%) 100 parts by weight, 50 parts by weight of methylol melamine at 30 ° C. It melt | dissolved in the pure water under temperature conditions, and prepared the aqueous solution with a solid content density | concentration of 3.7 weight%. A metal colloid-containing adhesive aqueous solution was prepared by adding 18 parts by weight of an aqueous solution containing a positively charged alumina colloid (average particle diameter of 15 nm) at a solid concentration of 10% by weight to 100 parts by weight of this aqueous solution. The viscosity of the adhesive solution was 9.6 mPa · s, the pH was in the range of 4 to 4.5, and the compounding amount of the alumina colloid was 74 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin.
The average particle size of the alumina colloid is measured by a dynamic light scattering method (light correlation method) with a particle size distribution meter (manufactured by Nikkiso, product name “Nanotrack UAP150”).

(Creation of a polarizing plate having a polyester film)
A biaxially stretched polyethylene terephthalate film having the easy-adhesion layer on one main surface of the polarizer and a retardation film made of a cellulose resin on the other main surface of the polarizer (trade name “trade name“ WVBZ made by Fuji Film) The adhesive was applied so that the thickness of the adhesive layer after drying was 80 nm, and was bonded using a roll machine, and dried at 70 ° C. for 6 minutes to prepare a polarizing plate. In addition, the arrangement | positioning of the biaxially-stretched polyethylene terephthalate film which has an easily bonding layer laminated | stacked so that the easily bonding layer forming surface of a polyester film and a polarizer might oppose. The polarizing plate with the optical compensation layer thus obtained is referred to as “polarizing plate A”.

(Polarizing plate without polyester film)
As a polarizing plate having no polyester film, a commercially available polarizing plate (trade name “NPF VEGQ1724DU” manufactured by Nitto Denko Corporation) in which a retardation film is laminated on one side of a polarizer was used. A retardation film made of a cellulose resin on one main surface of a polarizer made of a polyvinyl alcohol film containing benzene (trade name “WVBZ”, manufactured by Fuji Film), and a triacetyl cellulose film on the other main surface, respectively. This polarizing plate is referred to as “polarizing plate B”.

(Creation of LCD panel)
Take out the liquid crystal panel from a liquid crystal television (product name: BRAVIA KDL-32 S2500 made by Sony) equipped with a VA mode liquid crystal cell, remove the polarizing plate and the optical compensation film placed above and below the liquid crystal cell, Next, the glass surface (front and back) was washed, and then the polarizing plate A (condensing polarizing plate) was absorbed on the light source side surface of the liquid crystal cell, and the light source side polarizing plate placed in the original liquid crystal panel was absorbed. It arrange | positioned in the liquid crystal cell through the acrylic adhesive so that it might become the direction similar to an axial direction, and the surface by the side of the optical compensation layer of the polarizing plate A might oppose a liquid crystal cell.
Next, the polarizing plate B is placed on the viewing side surface of the liquid crystal cell so that the polarizing plate B has the same direction as the absorption axis direction of the viewing side polarizing plate disposed in the original liquid crystal panel. It arrange | positioned in the liquid crystal cell through the acrylic adhesive so that the surface by the side of an optical compensation layer might oppose a liquid crystal cell. In this way, a liquid crystal panel in which the polarizing plate A was disposed on one main surface of the liquid crystal cell and the polarizing plate B was disposed on the other main surface was obtained.

(Creation of liquid crystal display device)
The above-mentioned liquid crystal panel was incorporated into the original liquid crystal display device, the light source of the liquid crystal display device was turned on, and the luminance was measured 30 minutes later.

[Example 2]
(Preparation of polarizing plate)
In creating the polarizing plate (polarizing plate A) having the polyester film of Example 1, a biaxially stretched polyethylene terephthalate film (PET1) was used instead of the biaxially stretched polyethylene terephthalate film (PET1) (PTH38 manufactured by Unitika, 30% haze, hereinafter “ A polarizing plate with an optical compensation layer (referred to as “polarizing plate C”) was obtained in the same manner except that “PET2” was used.

(Production of liquid crystal panel and liquid crystal display device)
In the formation of the liquid crystal panel of Example 1, the polarizing plate C is used instead of the polarizing plate A, and the liquid crystal panel in which the polarizing plate C is disposed on one main surface of the liquid crystal panel and the polarizing plate B is disposed on the other main surface. Obtained. This liquid crystal panel was incorporated into the original liquid crystal display device, and the luminance was measured 30 minutes after the light source was turned on.

[Comparative Example 1]
(Preparation of polarizing plate)
(Production of liquid crystal panel and liquid crystal display device)
In the formation of the liquid crystal panel of Example 1, the polarizing plate B was used instead of the polarizing plate A to obtain a liquid crystal panel in which the polarizing plate B was disposed on both main surfaces of the liquid crystal panel. This liquid crystal panel was incorporated into the original liquid crystal display device, and the luminance was measured 30 minutes after the light source was turned on.

  The refractive index and haze of the polyester films (PET1 and PET2) and triacetylcellulose film (TAC) used above are listed in Table 1. Further, the measurement result of white luminance is shown in FIG. 8, and the contrast is shown in FIG.

  Further, based on the result shown in FIG. 8, the white luminance is half the luminance in the front direction (polar angle 0 °) (the luminance when normalized with the front direction luminance being 1 is 0.5). (This polar angle is referred to as “half-value angle”). Table 2 shows the value of the half-value angle and the result of confirming the presence or absence of coloring of the screen by visual observation.

◎ 画面に着色が認められない
○ 画面に若干の着色がみられるが許容範囲である
△ 画面に虹模様に着色している

◎ No coloration on the screen ○ Slight coloration on the screen is acceptable, but acceptable △ The screen is colored rainbow

  As can be seen from FIG. 8 and Table 2, in the liquid crystal display device of the example, the white luminance in the region where the polar angle is large is lower than that of the liquid crystal display device of the comparative example, and light is collected in the front direction. You can see that it is illuminated. Further, as shown in FIG. 9, it can be seen that the liquid crystal display device of the example has an improved front contrast as compared with the liquid crystal display device of the comparative example. Furthermore, it can be seen that, as in Example 2, coloring of the rainbow pattern is suppressed by increasing the haze of the protective film.

  In the above embodiment, the condensing polarizing plate (polarizing plate A or polarizing plate C) having a polyester film is disposed only on the light source side of the liquid crystal cell. However, the liquid crystal panel and the liquid crystal display device of the present invention have such a configuration. It is not limited, The same condensing effect can be acquired also in the structure by which the condensing polarizing plate is arrange | positioned only at the visual recognition side of a liquid crystal cell, or both main surfaces.

It is a schematic sectional drawing of the polarizing plate of this invention. (A) is an embodiment in which a protective film is laminated only on one main surface of the polarizer, and (b) is an embodiment in which protective films are laminated on both main surfaces of the polarizer. In the polarizing plate of this invention, when light injects into a 1st protective film, it is a conceptual diagram which represents typically a mode that light is condensed in a front direction. It is a schematic sectional drawing of the polarizing plate by preferable embodiment of this invention. 1 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. It is a flowchart which shows an example of the manufacturing method of the conventional liquid crystal panel. It is a flowchart showing an example of the manufacturing method of the liquid crystal panel of this invention. It is a schematic sectional drawing showing the structural example of the 1st optical film used for manufacture of the liquid crystal panel of this invention. It is a figure showing the polar angle dependence of the white luminance of the liquid crystal display device by an Example and a comparative example. It is a figure showing the polar angle dependence of the contrast of the liquid crystal display device by an Example and a comparative example.

Explanation of symbols

30 Polarizer 31 Protective Film 32 Protective Film 10 Liquid Crystal Cell 100 Liquid Crystal Panel 1 Polarizing Plate (First Sheet Product)
2 Polarizing plate (second sheet product)
80 Light source 120 Light guide plate 200 Light source unit 11 Optical film 12 Release film 14 Adhesive layer

Claims (10)

  A polarizing plate having a polarizer and a first protective film laminated on one main surface of the polarizer, wherein the average refractive index of the first protective film is 1.58 or more.   The polarizing plate of Claim 1 whose haze of a said 1st protective film is 2.0% or more.   The polarizing plate of Claim 1 which has a light-diffusion layer between the said polarizer and a said 1st protective film.   A second protective film is laminated on the main surface opposite to the first protective film of the polarizer, and the average refractive index of the second protective film is 1.55 or less. The polarizing plate in any one of Claims 1-3.   The polarizing plate of Claim 4 whose haze of a said 2nd protective film is 2.0% or less.   The polarizing plate according to claim 1, wherein the first protective film is a polyester film.   The polarizing plate according to claim 1, wherein the first protective film has an easy-adhesion layer formed on the surface of the protective film on the side laminated with the polarizer.   The polarizing plate according to any one of claims 1 to 7 is provided on at least one main surface of the liquid crystal cell, and the main surface on the opposite side of the first protective film of the light plate is opposed to the liquid crystal cell. Liquid crystal panel laminated on.   A liquid crystal display device comprising a light source unit on the side of the liquid crystal panel according to claim 8 on which the polarizing plate according to any one of claims 1 to 7 is disposed. A method for producing a liquid crystal panel according to claim 8,
A roll original fabric preparation step of preparing the long sheet of the polarizing plate according to any one of claims 1 to 7 as a roll original fabric,
A sheet cutting process for unwinding the sheet product from the roll and cutting the polarizing plate into a predetermined size using a cutting means;
After the cutting step, a bonding step of bonding the polarizing plate to a liquid crystal cell via an adhesive layer;
A method for producing a liquid crystal panel comprising:

Images