JP2018072710A - Polarization plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarization plate having a thin type polarization film, which can achieve a higher single body transmission factor and a lower orthogonal transmission factor in a short wavelength region in a high level.SOLUTION: A polarization plate has a polarization film with a thickness of 8 μm or less, and satisfies equations (1) Tc≤0.2×Y-8.5 and (2) 42.5≤Y (where Tcis an orthogonal transmission factor (%) in a wave length of 410 nm, and Y is a single body transmission factor (%) measured according to a 2 degree visual field (C light source) of JIS Z8701 and corrected in visual sensitivity).SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a polarizing plate.

  In a liquid crystal display device which is a typical image display device, polarizing plates are bonded to both sides of a liquid crystal cell due to the image forming method. Usually, a polarizing plate contains the protective layer which protects a polarizing film and a polarizing film. In recent years, thinning of image display devices has been demanded, and accordingly, thinning of polarizing plates has been demanded.

  By the way, the method of obtaining a polarizing film by forming a polyvinyl alcohol (PVA) type-resin layer on a resin base material and extending | stretching and dye | staining this laminated body is proposed (for example, patent document 1). According to such a method, a thin polarizing film (for example, 8 μm or less) polarizing film (hereinafter sometimes referred to as “thin polarizing film”) can be obtained, which can contribute to thinning of the image display device. Attention has been paid. On the other hand, for polarizing plates having a thin polarizing film, further improvement in polarization characteristics is required.

JP 2000-338329 A

  When the present inventors examined the polarization characteristics of a polarizing plate having a thin polarizing film, when the polarizing plate has high single transmittance, it also has orthogonal transmittance in a short wavelength region (for example, 380 nm to 430 nm). It turned out to be high, and it was found that light leakage (clear blue) could occur.

  The present invention has been made to solve the above newly recognized problems, and its main object is a polarizing plate having a thin polarizing film, which has a high single transmittance and a low short wavelength region orthogonal transmission. An object of the present invention is to provide a polarizing plate capable of satisfying both higher rate and lower rate.

The polarizing plate of the present invention has a polarizing film having a thickness of 8 μm or less and satisfies the following formulas (1) and (2).
Tc ₄₁₀ ≦ 0.2 × Y-8.5 formula (1)
42.5 ≦ Y Formula (2)
(In the formula, Tc ₄₁₀ is an orthogonal transmittance (%) at a wavelength of 410 nm, and Y is a single transmittance (%) measured by a two-degree field of view (C light source) of JIS Z8701 and corrected for visibility. is there.)
In one embodiment, the polarizing film contains a dye compound having a maximum absorption wavelength of an absorption spectrum in a wavelength region of 380 nm to 480 nm.
In one embodiment, the pressure-sensitive adhesive layer further includes a pressure-sensitive adhesive layer disposed on at least one side of the polarizing film, and the pressure-sensitive adhesive layer contains a dye compound having a maximum absorption wavelength of an absorption spectrum in a wavelength region of 380 nm to 480 nm.
In one embodiment, the protective layer further includes a protective layer disposed on at least one side of the polarizing film, and the protective layer includes a dye compound having a maximum absorption wavelength of an absorption spectrum in a wavelength region of 380 nm to 480 nm.
In one embodiment, the dye compound has a maximum absorption wavelength of an absorption spectrum in a wavelength region of 380 nm to 430 nm, and a half width of the absorption spectrum at the maximum absorption wavelength is 10 nm to 60 nm.
According to another aspect of the present invention, a liquid crystal panel is provided. The liquid crystal panel includes the polarizing plate.
According to still another aspect of the present invention, a liquid crystal display device is provided. The liquid crystal display device includes the liquid crystal panel.

  According to the present invention, it is possible to obtain a polarizing plate having a thin polarizing film and capable of achieving both high single transmittance and orthogonal transmittance in a low short wavelength region at a high order.

It is a schematic sectional drawing of the polarizing plate by one Embodiment of this invention. It is a schematic sectional drawing of the polarizing plate by another embodiment of this invention. It is a schematic sectional drawing of the polarizing plate by another embodiment of this invention. It is a graph showing the relationship between the single transmittance and cross transmittance of the polarizing plates obtained in Examples and Comparative Examples (Tc _410). It is a graph showing the relationship between the single transmittance and cross transmittance of the polarizing plates obtained in Examples and Comparative Examples (Tc _410).

A. Polarizing plate The polarizing plate of the present invention has a polarizing film having a thickness of 8 μm or less and satisfies the following formulas (1) and (2) simultaneously.
Tc ₄₁₀ ≦ 0.2 × Y-8.5 formula (1)
42.5 ≦ Y Formula (2)
In the formula, Tc ₄₁₀ is an orthogonal transmittance (%) at a wavelength of 410 nm, and Y is a single transmittance (%) measured by a two-degree field of view (C light source) of JIS Z8701 and corrected for visibility. .

  As defined in the above formula (2), the single transmittance (Y) of the polarizing plate of the present invention is 42.5% or more, preferably 43.0% or more. On the other hand, since the theoretical upper limit of the single transmittance (Y) of the polarizing plate is 50% and the practical upper limit is 46%, the formula (1) shows how the single transmittance (Y) is improved. Even so, it means that the orthogonal transmittance at a wavelength of 410 nm is sufficiently low. Therefore, the polarizing plate that satisfies the above formulas (1) and (2) simultaneously has both a sufficiently high single transmittance for practical use and an orthogonal transmittance in a short wavelength region sufficiently low for practical use. . Such a polarizing plate has been realized for the first time by the present invention, and the fact that such a polarizing plate can actually be provided is an industrially excellent effect.

The reason why such a polarizing plate has not been realized conventionally is as follows. That is, the thin polarizing film inevitably has a lower iodine content than a thick (for example, 20 μm or more) polarizing film due to its small thickness. From the viewpoint of achieving high optical characteristics with such a low iodine content, formation of a PVA-iodine complex having absorption in a wavelength region with high visibility is given priority in the production of a thin polarizing film. Therefore, the amount of iodine having absorption in the ultraviolet region (for example, free iodine ions (I ₃ ⁻ ) having maximum absorption near wavelengths of 290 nm and 360 nm) is reduced, and the polarization characteristics in the vicinity of the region are deteriorated. As a result, in a polarizing plate having a thin polarizing film, it has been difficult to achieve both a high polarization property near 550 nm and a short wavelength (400 nm) polarization property that has low visibility but has a large effect on hue. .

The orthogonal transmittance at a wavelength of 410 nm of the polarizing plate of the present invention is preferably 1% or less, more preferably 0.5% or less. The polarizing plate of the present invention preferably further satisfies the formula (3): Tc ₄₁₀ ≦ 0.2 × Y−8.55.

  Hereinafter, exemplary embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A-1. 1A is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention, FIG. 1B is a schematic cross-sectional view of a polarizing plate according to another embodiment of the present invention, and FIG. FIG. 5 is a schematic sectional view of a polarizing plate according to still another embodiment of the present invention. In FIG. 1A, the polarizing plate 100 </ b> A includes a polarizing film 10 and a first protective layer 21 provided on one side of the polarizing film 10. In FIG. 1B, the polarizing plate 100B includes a polarizing film 10, a first protective layer 21 provided on one side of the polarizing film 10, and an adhesive layer 30 provided on the other side of the polarizing film 10. 1C, a polarizing plate 100C includes a polarizing film 10, a first protective layer 21 provided on one side of the polarizing film 10, a second protective layer 22 provided on the other side of the polarizing film 10, And the pressure-sensitive adhesive layer 30 provided on the opposite side of the polarizing film 10 of the protective layer 22. Each of the first protective layer 21 and the second protective layer 22 may be provided on one side of the polarizing film 10 through an adhesive layer (not shown), and is in close contact with the polarizing film 10 without through the adhesive layer. It may be provided. Moreover, when a protective layer is provided on both sides of the polarizing film 10, these may have the same configuration or different configurations. The pressure-sensitive adhesive layer may be protected with a release film until it is practically used.

  In one embodiment, the polarizing plate of the present invention includes a dye compound having a maximum absorption wavelength of an absorption spectrum in a wavelength region of 380 nm to 480 nm. When the polarizing plate contains the dye compound, the orthogonal transmittance in the short wavelength region can be reduced while maintaining a high single transmittance. The dye compound may be included in any component of the polarizing plate. Examples of components of the polarizing plate that may contain the dye compound include a polarizing film, a protective layer, a pressure-sensitive adhesive layer, and an adhesive layer. The dye compound may be contained only in one component, or may be contained in two or more components. The maximum absorption wavelength means an absorption maximum wavelength exhibiting the maximum absorbance in the case of a plurality of absorption maximums in the spectral absorption spectrum in the wavelength region of 380 nm to 480 nm. .

  The dye compound is preferably a compound having a maximum absorption wavelength of an absorption spectrum in a wavelength region of 380 nm to 430 nm, and more preferably a compound having a maximum absorption wavelength of an absorption spectrum in a wavelength region of 380 nm to 420 nm. By using such a dye compound for the polarizing plate, the orthogonal transmittance in the short wavelength region can be suitably reduced while maintaining a high single transmittance.

The half width of the absorption spectrum at the maximum absorption wavelength of the dye compound is preferably 110 nm or less, more preferably 5 nm to 80 nm, and still more preferably 10 nm to 60 nm. When the full width at half maximum is in the above range, it is possible to prevent a decrease in optical characteristics in a region with high visibility (for example, a longer wavelength side than 430 nm). The half width is obtained, for example, by the following measurement method.
<Measurement method of half width>
The half width is measured from a transmission absorption spectrum of a solution of a dye compound under the following conditions using an ultraviolet-visible spectrophotometer (for example, U-4100, manufactured by Hitachi High-Tech Science Co., Ltd.). From the spectrum measured by adjusting the concentration so that the absorbance at the maximum absorption wavelength is 1.0, the wavelength interval (full width at half maximum) between two points at 50% of the peak value is defined as the half width of the dye compound. .
(Measurement condition)
Solvent: Toluene or chloroform Cell: Quartz cell Optical path length: 10 mm

  Examples of the dye compound include organic dye compounds and inorganic dye compounds. Among these, organic dye compounds are preferable from the viewpoint of maintaining dispersibility and transparency. The coloring compound may be used alone or in combination of two or more.

  Examples of the organic dye compounds include azomethine compounds, indole compounds, cinnamic acid compounds, pyrimidine compounds, porphyrin compounds, benzothiadiazole compounds, and the like.

  What is marketed can be used suitably as said organic pigment | dye compound. Specifically, as the indole compound, BONASORB UA3911 (trade name, maximum absorption wavelength of absorption spectrum: 398 nm, half-value width: 48 nm, manufactured by Orient Chemical Industry Co., Ltd.), BONASORB UA3912 (trade name, absorption spectrum) Maximum absorption wavelength: 386 nm, half-value width: 53 nm, manufactured by Orient Chemical Industry Co., Ltd., and cinnamic acid compounds as SOM-5-0106 (trade name, maximum absorption wavelength of absorption spectrum: 416 nm, half-value width: 50 nm, manufactured by Orient Chemical Industry Co., Ltd., and pyrimidine compounds, FDB-009 (trade name, maximum absorption wavelength of absorption spectrum: 394 nm, half-value width: 43 nm, manufactured by Yamada Chemical Industry Co., Ltd.), porphyrin compounds As FDB-001 (trade name, maximum absorption wave of absorption spectrum Long: 420 nm, half width: 14 nm, manufactured by Yamada Chemical Co., Ltd.).

  The blending amount of the dye compound can be appropriately set so that the polarizing plate satisfies the above formulas (1) and (2).

A-2. Polarizing Film The polarizing film is typically a polyvinyl alcohol (hereinafter referred to as “PVA”) resin film in which a dichroic substance is adsorbed and oriented. The thickness of the polarizing film is 8 μm or less, preferably 7 μm or less, more preferably 5 μm or less. On the other hand, the thickness of the polarizing film is preferably 0.5 μm or more, more preferably 1.0 μm or more.

  The polarizing film preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizing film is typically 42.5% or more, preferably 43.0% or more. The polarization degree of the polarizing film is preferably 99.8% or more, more preferably 99.9% or more, and further preferably 99.95% or more.

  Examples of the dichroic substance include iodine and organic dyes. These may be used alone or in combination of two or more. The dichroic material is preferably iodine.

  Arbitrary appropriate resin may be employ | adopted as PVA-type resin which forms the said PVA-type resin film. Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. An ethylene-vinyl alcohol copolymer can be obtained by saponifying an ethylene-vinyl acetate copolymer. The degree of saponification of the PVA resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. . The saponification degree can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a saponification degree, a polarizing film having excellent durability can be obtained. If the degree of saponification is too high, there is a risk of gelation.

  The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average degree of polymerization is usually 1000 to 10000, preferably 1200 to 4500, more preferably 1500 to 4300. The average degree of polymerization can be determined according to JIS K 6726-1994.

  Any appropriate method can be adopted as a method for manufacturing the polarizing film. Typically, the polarizing film is manufactured by performing various treatments on the PVA resin film. Any appropriate form can be adopted as the PVA-based resin film subjected to various treatments. Specifically, it may be a PVA resin film or a PVA resin layer formed on a resin substrate.

  In one embodiment, a PVA-based resin layer is formed on a resin substrate to produce a laminate, and a polarizing film is produced by performing various treatments on the laminate. A PVA-type resin layer is formed by apply | coating the coating liquid containing PVA-type resin to a resin base material, for example. As the coating solution, a solution obtained by dissolving a PVA resin in a solvent is typically used. Examples of the solvent for dissolving the PVA resin include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polymethyl alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. Used. These may be used alone or in combination of two or more. Among these, water is preferable. The concentration of the PVA resin in the solution is preferably 3 to 20 parts by weight with respect to 100 parts by weight of the solvent.

  The coating solution may contain an additive. Examples of the additive include a plasticizer and a surfactant. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. Examples of the surfactant include nonionic surfactants. These can be used for the purpose of further improving the uniformity, dyeability and stretchability of the resulting PVA-based resin layer. Moreover, as an additive, an easily bonding component is mentioned, for example. By using the easy-adhesion component, the adhesion between the resin base material and the PVA-based resin layer can be improved. As a result, for example, problems such as peeling of the PVA resin layer from the resin base material can be suppressed, and dyeing and underwater stretching described later can be performed satisfactorily. As the easily adhesive component, for example, modified PVA such as acetoacetyl-modified PVA is used. Furthermore, examples of the additive include halides such as potassium iodide, sodium iodide, lithium iodide and sodium chloride, urea and the like. By adding these, optical characteristics (for example, single transmittance) can be improved. The blending amount of the additive can be appropriately set according to the purpose and the like.

  In an embodiment in which the polarizing film contains the dye compound, typically, the dye compound is blended in the coating solution. The compounding amount of the coloring compound may be about 0.01 to 10 parts by weight, preferably about 0.02 to 5 parts by weight, with respect to 100 parts by weight of the PVA resin.

  Any appropriate method can be adopted as a coating method of the coating solution. Examples thereof include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, and a knife coating method (such as a comma coating method).

  The coating temperature of the coating solution is preferably 50 ° C. or higher. Preferably, the coating film is dried. The drying temperature is preferably 50 ° C. or higher.

  The thickness (before stretching) of the PVA-based resin layer is preferably 3 μm to 40 μm, and more preferably 3 μm to 20 μm.

  Any appropriate material can be adopted as a constituent material of the resin base material. Examples thereof include ester resins such as polyethylene terephthalate resins, cycloolefin resins, olefin resins such as polypropylene, (meth) acrylic resins, polyamide resins, polycarbonate resins, and copolymer resins thereof. Preferably, a polyethylene terephthalate resin is used. Among these, amorphous polyethylene terephthalate resin is preferably used. Specific examples of the amorphous polyethylene terephthalate resin include a copolymer further containing isophthalic acid as a dicarboxylic acid, and a copolymer further containing cyclohexanedimethanol as a glycol.

  The glass transition temperature (Tg) of the resin substrate is preferably 100 ° C. or lower. By using such a resin base material, it is possible to sufficiently ensure stretchability (particularly in water stretching) while suppressing crystallization of the PVA-based resin layer in stretching of the laminate described later. As a result, a polarizing film having excellent optical characteristics (for example, the degree of polarization) can be manufactured. On the other hand, the glass transition temperature of the resin substrate is preferably 60 ° C. or higher. In addition, a glass transition temperature (Tg) is a value calculated | required according to JISK7121.

  The thickness of the resin substrate is preferably 20 μm to 300 μm, more preferably 50 μm to 200 μm. The surface of the resin base material may be subjected to surface modification treatment (for example, corona treatment) or an easy-adhesion layer may be formed.

  Examples of the various treatments include dyeing treatment, stretching treatment, insolubilization treatment, crosslinking treatment, washing treatment, and drying treatment. These processes can be appropriately selected depending on the purpose. Further, the processing order, the processing timing, the number of processings, and the like can be set as appropriate. Each process will be described below.

(Dyeing process)
The dyeing process is typically performed by dyeing a PVA resin film with a dichroic substance. Preferably, the dichroic substance is adsorbed on the PVA resin film. Examples of the adsorption method include a method of immersing a PVA-based resin film (laminate) in a staining solution containing a dichroic substance, a method of applying the staining solution to a PVA-based resin film, and a method of applying the staining solution to a PVA system. Examples include a method of spraying on a resin film. Preferably, it is a method of immersing the laminate in the staining solution. It is because a dichroic substance can adsorb | suck favorably.

  When iodine is used as the dichroic substance, the staining solution is preferably an iodine aqueous solution. The compounding amount of iodine is preferably 0.1 part by weight to 0.5 part by weight with respect to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add an iodide to the aqueous iodine solution. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Etc. Among these, potassium iodide is preferable. The blending amount of iodide is preferably 0.02 to 20 parts by weight, more preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of water.

  The liquid temperature during dyeing of the dyeing liquid is preferably 20 ° C. to 50 ° C. in order to suppress dissolution of the PVA resin. When the PVA resin film is immersed in the staining solution, the immersion time is preferably 5 seconds to 5 minutes in order to ensure the transmittance of the PVA resin film. The staining conditions (concentration, liquid temperature, immersion time) can be set so that the polarization degree or single transmittance of the finally obtained polarizing film is within a predetermined range. In one embodiment, immersion time is set so that the polarization degree of the polarizing film obtained may be 99.98% or more. In another embodiment, the immersion time is set so that the single transmittance of the obtained polarizing film is 42.5% or more.

(Extension process)
Any appropriate method can be adopted as a method for stretching the laminate. Specifically, it may be fixed end stretching (for example, a method using a tenter stretching machine) or free end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). Moreover, simultaneous biaxial stretching (for example, a method using a simultaneous biaxial stretching machine) or sequential biaxial stretching may be used. The stretching of the laminate may be performed in one stage or in multiple stages. When performed in multiple stages, the draw ratio (maximum draw ratio) of the laminate described later is the product of the draw ratios of the respective stages.

  The stretching treatment may be an underwater stretching method performed by immersing the laminate in a stretching bath, or an air stretching method. Preferably, the underwater stretching treatment is performed at least once, and more preferably, the underwater stretching treatment and the air stretching treatment are combined. According to the stretching in water, the PVA resin film can be stretched at a temperature lower than the glass transition temperature (typically about 80 ° C.) of the resin base material or the PVA resin film while suppressing its crystallization. It can be stretched at a high magnification. As a result, a polarizing film having excellent optical characteristics (for example, the degree of polarization) can be manufactured.

  Any appropriate direction can be selected as the stretching direction of the laminate. In one embodiment, it extends | stretches in the longitudinal direction of an elongate laminated body. Specifically, the laminate is transported in the longitudinal direction, which is the transport direction (MD). In another embodiment, it extends | stretches in the width direction of an elongate laminated body. Specifically, the laminate is transported in the longitudinal direction, and the direction (TD) is orthogonal to the transport direction (MD).

  The stretching temperature of the laminate can be set to any appropriate value depending on the resin base material, the stretching method, and the like. When adopting the air stretching method, the stretching temperature is preferably equal to or higher than the glass transition temperature (Tg) of the resin substrate, more preferably the glass transition temperature (Tg) of the resin substrate + 10 ° C., and particularly preferably Tg + 15 ° C. That's it. On the other hand, the stretching temperature of the laminate is preferably 170 ° C. or lower. By stretching at such a temperature, it is possible to suppress rapid crystallization of the PVA-based resin and to suppress defects due to the crystallization (for example, preventing the orientation of the PVA-based resin film due to stretching). it can.

  When the underwater stretching method is adopted as the stretching method, the liquid temperature of the stretching bath is preferably 40 ° C to 85 ° C, more preferably 50 ° C to 85 ° C. If it is such temperature, it can extend | stretch at high magnification, suppressing melt | dissolution of a PVA-type resin film. Specifically, as described above, the glass transition temperature (Tg) of the resin base material is preferably 60 ° C. or higher in relation to the formation of the PVA-based resin film. In this case, when the stretching temperature is lower than 40 ° C., there is a possibility that the stretching cannot be satisfactorily performed even in consideration of plasticization of the resin base material with water. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin film, which may result in failure to obtain excellent optical properties.

  When employing an underwater stretching method, it is preferable to stretch the laminate by immersing it in an aqueous boric acid solution (stretching in boric acid in water). By using a boric acid aqueous solution as the stretching bath, the PVA resin film can be provided with rigidity that can withstand the tension applied during stretching and water resistance that does not dissolve in water. Specifically, boric acid can form a tetrahydroxyborate anion in an aqueous solution and crosslink with a PVA resin by hydrogen bonding. As a result, rigidity and water resistance can be imparted to the PVA-based resin film, the film can be stretched well, and a polarizing film having excellent optical properties can be produced.

  The boric acid aqueous solution is preferably obtained by dissolving boric acid and / or borate in water as a solvent. The boric acid concentration is preferably 1 to 10 parts by weight with respect to 100 parts by weight of water. By setting the boric acid concentration to 1 part by weight or more, dissolution of the PVA-based resin film can be effectively suppressed, and a polarizing film having higher characteristics can be produced. In addition to boric acid or borate, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, or the like in a solvent can also be used.

  Preferably, an iodide is blended in the stretching bath (boric acid aqueous solution). By blending iodide, elution of iodine adsorbed on the PVA resin film can be suppressed. Specific examples of the iodide are as described above. The concentration of iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight with respect to 100 parts by weight of water.

  The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.

  The draw ratio (maximum draw ratio) of the laminate is preferably 5.0 times or more with respect to the original length of the laminate. Such a high draw ratio can be achieved, for example, by employing an underwater drawing method (boric acid underwater drawing). In the present specification, the “maximum stretch ratio” refers to a stretch ratio immediately before the laminate is ruptured. Separately, a stretch ratio at which the laminate is ruptured is confirmed, and a value that is 0.2 lower than that value. .

  Preferably, the underwater stretching process is performed after the dyeing process.

(Insolubilization treatment)
The insolubilization treatment is typically performed by immersing a PVA resin film in an aqueous boric acid solution. In particular, when an underwater stretching method is employed, water resistance can be imparted to the PVA-based resin film by performing insolubilization treatment. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilizing bath (boric acid aqueous solution) is preferably 20 ° C to 40 ° C. Preferably, the insolubilization process is performed after the laminate is manufactured and before the dyeing process or the underwater stretching process.

(Crosslinking treatment)
The crosslinking treatment is typically performed by immersing a PVA resin film in an aqueous boric acid solution. By performing the crosslinking treatment, water resistance can be imparted to the PVA resin film. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. Moreover, when performing a crosslinking process after the said dyeing | staining process, it is preferable to mix | blend an iodide further. By blending iodide, elution of iodine adsorbed on the PVA resin film can be suppressed. The blending amount of iodide is preferably 1 part by weight to 5 parts by weight with respect to 100 parts by weight of water. Specific examples of the iodide are as described above. The liquid temperature of the crosslinking bath (boric acid aqueous solution) is preferably 20 ° C to 50 ° C. Preferably, the crosslinking treatment is performed before the underwater stretching treatment. In a preferred embodiment, the dyeing process, the crosslinking process and the underwater stretching process are performed in this order.

(Cleaning process)
The cleaning treatment is typically performed by immersing a PVA resin film in an aqueous potassium iodide solution.

(Drying process)
The drying temperature in the drying process is preferably 30 ° C to 100 ° C.

A-3. Protective layer As the protective layer, the resin substrate used in the production of the polarizing film can be used as it is. Or a polarizing film can be transcribe | transferred to arbitrary appropriate resin films from a resin base material, and this resin film can be used as a protective layer. In the embodiment in which the protective layer is provided on both sides of the polarizing film, for example, the resin base material is used as it is as the first protective layer, and the polarizing film is arbitrarily disposed on the side opposite to the side on which the resin base material is disposed. A suitable resin film can be laminated to form the second protective layer. In addition, for example, the polarizing film is transferred from the resin base material to any appropriate resin film to form the first protective layer, and another arbitrary side of the polarizing film opposite to the side on which the first protective layer is disposed. A suitable resin film can be laminated to form the second protective layer.

  When using a resin film as a protective layer, this resin film is typically laminated | stacked on a polarizing film through an contact bonding layer. The adhesive layer is typically formed of an adhesive or a pressure-sensitive adhesive. Examples of the adhesive forming the adhesive layer include aqueous adhesives such as isocyanate adhesives and polyvinyl alcohol adhesives, ultraviolet curable adhesives, and electron beam curable adhesives.

  The resin film may be excellent in isotropy, or may have a phase difference and function as an optical compensation layer. When a resin film having a retardation is used, the retardation characteristics can be appropriately adjusted to a value required for optical compensation.

  Examples of the material for forming the resin film include (meth) acrylic resins, cellulose resins such as diacetyl cellulose and triacetyl cellulose, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, and polyethylene terephthalate systems. Examples thereof include ester resins such as resins, polyamide resins, polycarbonate resins, and copolymer resins thereof. The “(meth) acrylic resin” refers to an acrylic resin and / or a methacrylic resin.

  In one embodiment, a (meth) acrylic resin having a glutarimide structure is used as the (meth) acrylic resin. Examples of (meth) acrylic resins having a glutarimide structure (hereinafter also referred to as glutarimide resins) include, for example, JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, and JP-A-2006-328329. 2006-328334, JP-A 2006-337491, JP-A 2006-337492, JP-A 2006-337493, JP-A 2006-337469, JP-A 2007-009182, JP-A 2009- No. 161744 (for example, Production Example 1) and JP 2010-284840 A. These descriptions are incorporated herein by reference.

  In the embodiment in which the protective layer contains the dye compound, the amount of the dye compound in the protective layer is, for example, about 0.01 to 10 parts by weight, preferably 0.02 with respect to 100 parts by weight of the resin solid content. It may be about 5 to 5 parts by weight.

  The resin film is formed by any appropriate method. Examples of the film forming method include a melt extrusion method, a solution casting method (solution casting method), a calendar method, and a compression molding method. Among these, the melt extrusion method is preferable. Further, the resin film may be subjected to a stretching treatment.

  The average transmittance at a wavelength of 450 nm to 500 nm of the protective layer containing the dye compound is preferably 70% or more, more preferably 75% or more, and the average transmittance at a wavelength of 500 nm to 780 nm is preferably 80% or more. Preferably it is 85% or more. In the present specification, the “average transmittance at a wavelength of 400 to 430 nm” refers to an average value of the calculated transmittances obtained by calculating the transmittance at a pitch of 5 nm in a wavelength range of 400 to 430 nm. The same applies to the average transmittance in other wavelength regions.

  The thickness of the protective layer is generally 10 μm to 100 μm, preferably 10 μm to 50 μm, more preferably 10 μm to 30 μm.

A-4. Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition. In the embodiment in which the pressure-sensitive adhesive layer contains the dye compound, typically, the dye compound is blended in the pressure-sensitive adhesive composition.

  The pressure-sensitive adhesive composition is preferably a heat-crosslinking pressure-sensitive adhesive composition containing a base polymer and a crosslinking agent. Since it is not necessary to contain a photoinitiator, it is possible to prevent the absorption of the dye compound and the absorption of the photoinitiator from interfering with each other when the dye compound is added to the pressure-sensitive adhesive composition.

  As said adhesive composition, it can be set as adhesives, such as an acrylic type, a synthetic rubber type, a rubber type, and a silicone type. From the viewpoints of transparency and heat resistance, an acrylic pressure-sensitive adhesive having a (meth) acrylic polymer as a base polymer is preferred.

  The (meth) acrylic polymer is preferably obtained by polymerizing a monomer component containing a (meth) acrylic acid ester having an alkyl group having 2 to 14 carbon atoms, and has an alkyl group having 2 to 14 carbon atoms. More preferably, it is obtained by polymerizing a monomer component containing a (meth) acrylic acid ester as a main monomer. Here, the main monomer is preferably 60% by weight or more, and more preferably 70% by weight or more based on all monomer components constituting the (meth) acrylic polymer. In the present specification, “(meth) acryl” means acryl and / or methacryl.

  Examples of the (meth) acrylic acid ester having an alkyl group having 2 to 14 carbon atoms include ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, Hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate , Isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, and the like. These may be used alone or in combination of two or more. Can be used

  The monomer component may contain other polymerizable monomer other than the (meth) acrylic acid ester having an alkyl group having 2 to 14 carbon atoms. The other polymerizable monomer is not particularly limited as long as it has a polymerizable functional group related to an unsaturated double bond such as a (meth) acryloyl group or a vinyl group. For example, a hydroxyl group-containing monomer, carboxyl And group-containing monomers.

  As the hydroxyl group-containing monomer, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a hydroxyl group can be used without particular limitation. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl ( (Meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl (meth) acrylate, and the like, and these may be used alone or in combination. Two or more kinds can be mixed and used.

  The content of the hydroxyl group-containing monomer is preferably 10% by weight or less in the monomer component, more preferably 0 to 5% by weight, and further preferably 0.1 to 2% by weight.

  As the carboxyl group-containing monomer, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a carboxyl group can be used without particular limitation. Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. These may be used alone or in combination. Can be used.

  The content of the carboxyl group-containing monomer is preferably 5% by weight or less in the monomer component.

  Other copolymerization monomers are not particularly limited as long as they have a polymerizable functional group related to an unsaturated double bond such as a (meth) acryloyl group or a vinyl group. For example, cyclohexyl (meth) acrylate, (Meth) acrylic acid alicyclic hydrocarbon esters such as (meth) acrylic acid bornyl and (meth) acrylic acid isobornyl; for example, (meth) acrylic acid aryl esters such as phenyl (meth) acrylate; for example, vinyl acetate, Vinyl esters such as vinyl propionate; for example, styrenic monomers such as styrene; for example, epoxy group-containing monomers such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; for example, acrylamide, diethylacrylamide, acryloylmorpholine (ACMO), N-vinylpyrrolidone Amide group-containing monomers such as NVP); for example, amino group-containing monomers such as N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate; for example, N-vinylpyrrolidone, N- Cyclic nitrogen-containing monomers such as vinyl-ε-caprolactam and methylvinylpyrrolidone; for example, alkoxy group-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; for example, cyano such as acrylonitrile and methacrylonitrile Group-containing monomers; for example, functional monomers such as 2-methacryloyloxyethyl isocyanate; for example, olefinic monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; for example, vinyl ether monomers such as vinyl ether For example, halogen atom-containing monomers such as vinyl chloride; N-vinylcarboxylic acid amides and the like.

  Examples of copolymerizable monomers include maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; for example, N-methylitaconimide, N-ethylitaconimide, N -Itaconic imide monomers such as butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexyl leuconacimide, N-lauryl itaconimide; N- (meth) acryloyloxymethylene succinimide, N- Succinimide monomers such as (meth) acryloyl-6-oxyhexamethylene succinimide and N- (meth) acryloyl-8-oxyoctamethylene succinimide; for example, styrene sulfonic acid, allyl Examples include sulfonic acid group-containing monomers such as sulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamidepropanesulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloyloxynaphthalenesulfonic acid. .

  Moreover, as copolymerizable monomers, for example, glycol acrylic ester monomers such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, etc. Other examples include, for example, tetrahydrofurfuryl (meth) acrylate, a heterocyclic ring such as fluorine (meth) acrylate, and an acrylate monomer containing a halogen atom.

  Furthermore, a polyfunctional monomer can be used as the copolymerizable monomer. Examples of the polyfunctional monomer include compounds having two or more unsaturated double bonds such as a (meth) acryloyl group and a vinyl group. For example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetraethylene glycol di (meth) acrylate, etc. (mono or poly) In addition to (mono or poly) alkylene glycol di (meth) acrylate such as (mono or poly) propylene glycol di (meth) acrylate such as ethylene glycol di (meth) acrylate and propylene glycol di (meth) acrylate, neopentyl glycol Di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pen Esterified product of (meth) acrylic acid and polyhydric alcohol such as erythritol tri (meth) acrylate and dipentaerythritol hexa (meth) acrylate; polyfunctional vinyl compound such as divinylbenzene; allyl (meth) acrylate, (meth) Examples thereof include compounds having a reactive unsaturated double bond such as vinyl acrylate. Polyfunctional monomers include polyesters (meta) having two or more unsaturated double bonds such as (meth) acryloyl groups and vinyl groups added to the backbone of polyester, epoxy, urethane, etc. as functional groups similar to the monomer components. ) Acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, and the like can also be used.

  The proportion of the copolymerization monomer other than the hydroxyl group-containing monomer and the carboxyl group-containing monomer is preferably 40% by weight or less, more preferably 0 to 30% by weight, and still more preferably 0 to 20% by weight in the monomer component.

  The weight average molecular weight of the (meth) acrylic polymer is preferably in the range of 1,200,000 to 3,000,000, more preferably 1,200,000 to 2,700,000, and even more preferably 1,200,000 to 2,500,000. When the weight average molecular weight is within the range, heat resistance, transparency, corrosion resistance, durability and the like can be excellent. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

  The production of the (meth) acrylic polymer can be appropriately selected from known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations. Further, the obtained (meth) acrylic polymer may be a random copolymer, a block copolymer, or a graft copolymer.

  In solution polymerization, for example, ethyl acetate, toluene or the like is used as a polymerization solvent. As a specific example of solution polymerization, the reaction is performed under an inert gas stream such as nitrogen and a polymerization initiator is added, and the reaction is usually performed at about 50 to 70 ° C. under reaction conditions for about 5 to 30 hours.

  The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited, and can be appropriately selected and used. In addition, the weight average molecular weight of a (meth) acrylic-type polymer can be controlled by the usage-amount of a polymerization initiator and a chain transfer agent, and reaction conditions, and the usage-amount is suitably adjusted according to these kinds.

  Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [2- (5-methyl-2). -Imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'-dimethyleneisobutylamidine), 2,2 Azo initiator such as' -azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (trade name: VA-057, manufactured by Wako Pure Chemical Industries, Ltd.), potassium persulfate, Persulfates such as ammonium sulfate, di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-s c-butyl peroxydicarbonate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1, 1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di (4-methylbenzoyl) peroxide, benzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexyl) Peroxy) peroxides such as cyclohexane, t-butyl hydroperoxide, hydrogen peroxide, peroxides and sodium bisulfite, peroxides and sodium ascorbate And redox initiators combined with an agent.

  The polymerization initiator may be used alone, or may be used in combination of two or more, but the total content is 100 weight of monomer components forming the (meth) acrylic polymer. The amount is preferably about 0.005 to 1 part by weight with respect to parts.

  Various silane coupling agents can be added to the pressure-sensitive adhesive composition in order to improve adhesion under high-temperature and high-humidity conditions. As the silane coupling agent, one having any appropriate functional group can be used. Examples of the functional group include vinyl group, epoxy group, amino group, mercapto group, (meth) acryloxy group, acetoacetyl group, isocyanate group, styryl group, polysulfide group and the like. Specifically, for example, vinyl group-containing silane coupling agents such as vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane; γ-glycidoxypropyltrimethoxysilane, γ-glycol Epoxy group-containing silane coupling agents such as sidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, γ-triethoxysilyl-N- (1,3-dimethylbutylidene) Propylamine, N-phenyl-γ- Amino group-containing silane coupling agents such as minopropyltrimethoxysilane; γ-mercaptopropylmethyldimethoxysilane and other mercapto group-containing silane coupling agents; p-styryltrimethoxysilane and other styryl group-containing silane coupling agents; (Meth) acrylic group-containing silane coupling agents such as acryloxypropyltrimethoxysilane and γ-methacryloxypropyltriethoxysilane; isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane; bis (triethoxysilyl) And polysulfide group-containing silane coupling agents such as propyl) tetrasulfide.

  The silane coupling agent may be used alone or in combination of two or more, but the total content is based on 100 parts by weight of the base polymer (solid content), The amount is preferably 1 part by weight or less, more preferably 0.01 to 1 part by weight, and further preferably 0.02 to 0.8 part by weight. When the amount of the silane coupling agent exceeds 1 part by weight, an unreacted coupling agent component is generated, which is not preferable from the viewpoint of durability.

  In addition, when the said silane coupling agent can be copolymerized with the said monomer component by radical polymerization, the said silane coupling agent can be used as said monomer component. The proportion is preferably 0.005 to 0.7 parts by weight with respect to 100 parts by weight of the base polymer (solid content).

  Furthermore, it is preferable to add a crosslinking agent to the above-mentioned pressure-sensitive adhesive composition because it can impart cohesive force related to the durability of the pressure-sensitive adhesive.

  As the cross-linking agent, a polyfunctional compound is used, and an organic cross-linking agent and a polyfunctional metal chelate are exemplified. Examples of the organic crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, a carbodiimide crosslinking agent, an imine crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, and a peroxide crosslinking agent. A polyfunctional metal chelate is one in which a polyvalent metal atom is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. Can be mentioned. Examples of the atom in the organic compound that is covalently bonded or coordinated include an oxygen atom, and examples of the organic compound include an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, and a ketone compound. These crosslinking agents can be used alone or in combination of two or more. Among these, a peroxide type crosslinking agent and an isocyanate type crosslinking agent are preferable, and it is more preferable to use these in combination.

  The said isocyanate type crosslinking agent means the compound which has two or more isocyanate groups (including the isocyanate reproduction | regeneration type functional group which protected the isocyanate group temporarily by the blocking agent or quantification etc.) in 1 molecule.

  Examples of the isocyanate-based crosslinking agent include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

  Various peroxides are used as the peroxide-based crosslinking agent. Examples of peroxides include di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate, and t-butylperoxyneodecanoate. , T-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxyisobutyrate, 1 1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, di (4-methylbenzoyl) peroxide, benzoyl peroxide, t-butylperoxyisobutyrate and the like. Among these, di (4-t-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, and benzoyl peroxide, which are particularly excellent in crosslinking reaction efficiency, are preferably used.

  The blending ratio of the crosslinking agent in the pressure-sensitive adhesive composition is usually blended at a ratio of about 10 parts by weight or less of the crosslinking agent (solid content) with respect to 100 parts by weight of the base polymer (solid content). The blending ratio of the crosslinking agent is preferably 0.01 to 10 parts by weight, and more preferably about 0.01 to 5 parts by weight. In particular, when a peroxide-based crosslinking agent is used, it is preferably about 0.05 to 1 part by weight, and 0.06 to 0.5 part by weight with respect to 100 parts by weight of the base polymer (solid content). More preferred.

  Various additives can be appropriately used in the pressure-sensitive adhesive composition as necessary without departing from the object of the present invention. Additives include viscosity modifiers, release modifiers, tackifiers, plasticizers, softeners, fillers made of glass fibers, glass beads, metal powders, other inorganic powders, pigments, colorants (pigments, dyes) Etc.), pH adjusters (acid or base), antioxidants, ultraviolet absorbers and the like.

  Moreover, as above-mentioned, when an adhesive layer contains the said pigment | dye compound, typically a pigment | dye compound is mix | blended with an adhesive composition. The compounding amount of the coloring compound in the pressure-sensitive adhesive composition can be, for example, about 0.01 to 10 parts by weight, preferably about 0.02 to 5 parts by weight, with respect to 100 parts by weight of the polymer solid content. .

  The pressure-sensitive adhesive layer can be formed, for example, by applying the pressure-sensitive adhesive composition on a substrate and arbitrarily drying or curing it. As the substrate, the above protective layer or polarizing film can be used. Further, any appropriate release film may be used as the base material.

  Any appropriate method can be used as a method of applying the pressure-sensitive adhesive composition onto the substrate. Examples of the method include roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, and die coater. Can be mentioned.

  The average transmittance at a wavelength of 400 nm to 430 nm of the pressure-sensitive adhesive layer containing the dye compound is preferably 30% or less, more preferably 20% or less. Moreover, the average transmittance at a wavelength of 450 nm to 500 nm of the pressure-sensitive adhesive layer containing the dye compound is preferably 70% or more, more preferably 75% or more, and the average transmittance at a wavelength of 500 nm to 780 nm is preferably 80%. More preferably, it is 85% or more.

  The thickness of the pressure-sensitive adhesive layer is preferably 7 μm or more, more preferably 10 μm or more, and further preferably 15 μm or more, from the viewpoint of ensuring the function of absorbing light having a wavelength of less than 430 nm. The upper limit value of the thickness of the pressure-sensitive adhesive layer can be, for example, 80 μm or less.

B. Liquid crystal panel The liquid crystal panel of this invention contains a liquid crystal cell and the polarizing plate arrange | positioned at the both sides of this liquid crystal cell. At least one of the polarizing plates arranged on both sides of the liquid crystal cell is the polarizing plate, preferably both are the polarizing plates.

C. Liquid crystal display device The liquid crystal display device of this invention is equipped with the said liquid crystal panel. In the liquid crystal display device of the present invention, the liquid crystal panel is arranged by any appropriate method.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In the examples, unless otherwise specified, the thickness was measured using a digital micrometer (trade name “KC-351C” manufactured by Anritsu Co., Ltd.).

[Production Example 1 Production of pressure-sensitive adhesive composition (A1)]
<Preparation of (meth) acrylic polymer>
A monomer mixture containing 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (HBA) was charged into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. .
Furthermore, with respect to 100 parts by weight of the monomer mixture (solid content), 0.1 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator was charged together with ethyl acetate, and nitrogen gas was added while gently stirring. After introducing nitrogen and replacing with nitrogen, a polymerization reaction was carried out for 7 hours while maintaining the liquid temperature in the flask at around 55 ° C. Then, ethyl acetate was added to the resulting reaction solution to prepare a (meth) acrylic polymer solution having a weight average molecular weight of 1,600,000 adjusted to a solid content concentration of 30%.

<Preparation of acrylic pressure-sensitive adhesive composition>
0.1 parts by weight of an isocyanate-based crosslinking agent (trade name: Takenate D110N, trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals, Inc.) with respect to 100 parts by weight of the solid content of the obtained (meth) acrylic polymer solution Benzoyl peroxide (trade name: Nyper BMT, manufactured by NOF Corporation) and a silane coupling agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) Benzothiadiazole compound dissolved in ethyl acetate to a solid content of 5% (a dye compound represented by the following formula (I), absorption spectrum maximum absorption wavelength: 420 nm, fluorescence quantum yield: 93%) Then, 0.1 part by weight (solid content weight) was added and stirred to obtain an acrylic pressure-sensitive adhesive composition (A1).

<Preparation of adhesive layer>
The acrylic pressure-sensitive adhesive composition (A1) is uniformly applied to the surface of a release film made of a polyethylene terephthalate film (PET film, transparent substrate) having a thickness of 38 μm treated with a silicone-based release agent, using a fountain coater. And dried for 2 minutes in a constant temperature oven at 155 ° C. to form an adhesive layer having a thickness of 20 μm.

[Production Example 2 Production of pressure-sensitive adhesive composition (A2)]
A pressure-sensitive adhesive composition (A2) was obtained in the same manner as in Production Example 1, except that the amount of the benzothiadiazole compound added was 0.3 parts by weight (solid content weight).

[Production Example 3 Production of pressure-sensitive adhesive composition (A3)]
A pressure-sensitive adhesive composition (A3) was obtained in the same manner as in Production Example 1 except that the addition amount of the benzothiadiazole compound was 0.6 parts by weight (solid content weight).

[Production Example 4 Production of Adhesive Composition (B)]
Instead of 0.1 parts by weight (solid weight) of the benzothiadiazole compound, BONASORB UA3911 (trade name, indole compound represented by the following formula (II), absorption spectrum maximum absorption wavelength: 398 nm, half-value width: 48 nm, orient chemistry A pressure-sensitive adhesive composition (B) was obtained in the same manner as in Production Example 1 except that 1 part by weight (solid weight) manufactured by Kogyo Co., Ltd. was used.

[Production Example 5 Production of pressure-sensitive adhesive composition (C)]
Instead of 0.1 parts by weight (solid weight) of the benzothiadiazole compound, FDB-009 (trade name, metrocyanine dye represented by the following formula (III), absorption spectrum maximum absorption wavelength: 394 nm, half-value width: 43 nm, Yamada A pressure-sensitive adhesive composition (C) was obtained in the same manner as in Production Example 1 except that 1 part by weight (solid content weight) was used.

[Production Example 6 Production of pressure-sensitive adhesive composition (D)]
A pressure-sensitive adhesive composition (D) was obtained in the same manner as in Production Example 1 except that the benzothiadiazole compound was not added.

[Production Example 7 Production of resin film for protective layer]
An acrylic film having a thickness of 40 μm and a moisture permeability of 80 g / m ^{2 made} of a methacrylic resin having a glutarimide ring unit produced in the same manner as in Production Example 1 of JP-A-2009-161744 was obtained.

[Example 1]
(Polarizing film)
As a resin base material, an amorphous polyethylene terephthalate (IPA copolymerized PET) film having a thickness of 100 μm and a Tg of 75 ° C. isophthalic acid unit of 7 mol% was prepared. The surface of this film was subjected to corona treatment (58 W / m ² / min).
Acetacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Gohsephimer Z200, average polymerization degree: 1200, saponification degree: 99.0 mol%, acetoacetylation degree: 5%; 1 part by weight) and PVA (Average polymerization degree: 4200, saponification degree: 99.2 mol%; 9 parts by weight), and 13 parts by weight of potassium iodide is added to 100 parts by weight of the PVA resin. Thus, a PVA-based resin aqueous solution was prepared (PVA-based resin concentration: 5.5% by weight). This aqueous solution is applied to the corona-treated surface of the resin substrate so that the film thickness after drying is 13 μm, and dried for 10 minutes by hot air drying in an atmosphere of 60 ° C. A resin layer was formed. Thus, a laminate was produced.
The obtained laminate was first stretched 2.4 times in air at 140 ° C. (air-assisted stretching).
Next, the laminate was immersed in an aqueous boric acid solution having a liquid temperature of 30 ° C. for 30 seconds to insolubilize the PVA resin layer. The boric acid aqueous solution in this step had a boric acid content of 3 parts by weight with respect to 100 parts by weight of water.
Next, the laminate was dyed in a staining solution containing iodine and potassium iodide at a liquid temperature of 30 ° C. for an arbitrary time so that the single transmittance of the obtained polarizing film was about 42 to 45%. The staining solution uses water as a solvent, an iodine concentration within a range of 0.1 to 0.4% by weight, a potassium iodide concentration within a range of 0.7 to 2.8% by weight, iodine and potassium iodide. The concentration ratio was 1: 7.
Next, the laminate was immersed in an aqueous boric acid solution at 30 ° C. for 60 seconds, and the PVA resin layer on which iodine was adsorbed was subjected to crosslinking treatment. The boric acid aqueous solution in this step had a boric acid content of 3 parts by weight with respect to 100 parts by weight of water and a potassium iodide content of 3 parts by weight with respect to 100 parts by weight of water.
Further, the laminate was stretched 2.3 times in a boric acid aqueous solution at a stretching temperature of 70 ° C. in the same direction as the previous air-assisted stretching (final draw ratio: 5.50 times). The boric acid aqueous solution in this step had a boric acid content of 3.5 parts by weight with respect to 100 parts by weight of water and a potassium iodide content of 5 parts by weight with respect to 100 parts by weight of water.
Next, the laminate is washed with an aqueous solution having a potassium iodide content of 4 parts by weight with respect to 100 parts by weight of water and dried with hot air at 60 ° C. to obtain a polarizing film having a thickness of 5 μm on the resin substrate. It was.

(Polarizer)
The acrylic film of Production Example 7 was bonded to the obtained polarizing film (on the side opposite to the resin substrate) through a curable adhesive. Specifically, a curable adhesive was applied on an acrylic film so as to have a thickness of 1.0 μm, and bonded using a roll machine. Thereafter, the visible light was irradiated from the acrylic film side to cure the curable adhesive.
Next, the pressure-sensitive adhesive layer obtained in Production Example 1 is bonded onto the acrylic film to obtain a polarizing plate having a structure of resin base material / polarizing film / acrylic film / pressure-sensitive adhesive layer / release film. It was.

[Examples 2-1 and 2-2]
A polarizing plate was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive composition (A2) was used instead of the pressure-sensitive adhesive composition (A1) to form a pressure-sensitive adhesive layer.

[Examples 3-1 and 3-2]
A polarizing plate was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive composition (A3) was used instead of the pressure-sensitive adhesive composition (A1) to form a pressure-sensitive adhesive layer.

[Examples 4-1 to 4-4]
A polarizing plate was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive composition (B) was used instead of the pressure-sensitive adhesive composition (A1) to form a pressure-sensitive adhesive layer.

[Examples 5-1 to 5-4]
A polarizing plate was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive composition (C) was used instead of the pressure-sensitive adhesive composition (A1) to form a pressure-sensitive adhesive layer.

[Comparative Examples 1-1 to 1-11]
A polarizing plate was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive composition (D) was used instead of the pressure-sensitive adhesive composition (A1) to form a pressure-sensitive adhesive layer.

[Comparative Examples 2-1 to 2-3]
(Polarizing film)
A polarizing film was produced according to the method described in Example 1 of JP2013-182162A. Specifically, it is as follows.
An unstretched polypropylene (PP) film (melting point: 163 ° C.) having a thickness of 100 μm was used as a resin substrate.
Using polyvinyl alcohol (hereinafter referred to as PVA) powder (Z-200 manufactured by Nippon Synthetic Chemical Industry Co., Ltd .: average polymerization degree 1200, saponification degree 99.0 mol%), it is dissolved in hot water at 95 ° C., and 3 w% aqueous solution. Adjusted. The obtained aqueous solution was applied onto a corona-treated resin base material using an applicator manufactured by Tester Sangyo Co., Ltd. and dried in an oven maintained at 80 ° C. for 10 minutes to form a primer layer having a thickness of 0.2 μm. Formed.
A 10 w% PVA aqueous solution (JF-23 manufactured by Nihon Vineyard-Poval Co., Ltd .: average polymerization degree 2400, saponification degree 98.0-99.0 mol%) was used on the primer layer using an applicator manufactured by Tester Sangyo Co., Ltd. And coated. The coating film was dried in an oven maintained at 80 ° C. for 20 minutes to produce a laminate of resin base material / primer layer / PVA resin layer.
The obtained laminate was subjected to 5.8 times free end uniaxial stretching in the longitudinal direction in an oven maintained at 160 ° C. to obtain a stretched film. The thickness of the PVA layer after stretching was 6.0 μm.
The obtained stretched film is immersed in an aqueous solution of 0.35 w% iodine, 10 w% potassium iodide, and a liquid temperature of 26 ° C. for an arbitrary time so that the single transmittance of the obtained polarizing film is about 42 to 45%. It was.
Next, it was immersed in an aqueous solution of 5.0 w% potassium iodide, 9.5 w% boric acid, and a liquid temperature of 76 ° C. for 300 seconds.
Furthermore, after washing by immersing in pure water having a liquid temperature of 10 ° C. for 10 seconds, the substrate was dried in an oven maintained at 80 ° C. for 200 seconds.
In this way, a polarizing film having a thickness of 6.0 μm was obtained on the resin substrate.

(Polarizer)
Example 1 except that the polarizing film obtained as described above was used and that the pressure-sensitive adhesive layer was formed using the pressure-sensitive adhesive composition (D) instead of the pressure-sensitive adhesive composition (A). Similarly, a polarizing plate was produced.

The following measurements were performed on the polarizing plates obtained in each Example and Comparative Example.
(Optical properties of polarizing plate)
The single transmittance and orthogonal transmittance (Tc ₄₁₀ ) of the polarizing plate were measured using an ultraviolet-visible spectrophotometer (V7100 manufactured by JASCO Corporation). The single transmittance is a Y value measured by JIS Z 8701's two-degree field of view (C light source) and corrected for visibility. The orthogonal transmittance (Tc ₄₁₀ ) is an orthogonal transmittance at a wavelength of 410 nm. The measurement was performed in a state where the resin substrate was peeled from the polarizing plate (that is, a configuration of [polarizing film / acrylic film / adhesive layer / acrylic film]). This is to eliminate the influence on the measurement result due to the difference in surface reflection of the resin base material. In any of the examples and comparative examples, the refractive index of the acrylic film is approximately 1.50, the refractive index of the polarizing film is approximately 1.53, and the combination of the refractive indices of the outermost surfaces is 1.50 / 1.53. The measurement was performed with a configuration that does not affect the measurement result due to surface reflection. The results are shown in Table 1. Also shown single axis transmittance (Y) and perpendicular transmittance graph showing the relationship between _{(Tc 410)} in FIGS. The graph of FIG. 3 is an enlarged graph of the range in which the orthogonal transmittance (Tc ₄₁₀ ) in the graph of FIG. 2 is 0.5% or less.

As shown in Table 1 and FIGS. 2 and 3, all of the polarizing plates of the examples satisfy both the expressions (1) and (2), and have a high single transmittance and a low orthogonal transmittance (Tc ₄₁₀ ). Are compatible. On the other hand, the polarizing plate of the comparative example, does not satisfy both the equations (1) and (2), the single transmittance is high, crossed transmittance (Tc ₄₁₀₎ also tended to be higher.

  The polarizing plate of this invention is used suitably for an image display apparatus. Specifically, it is suitably used for liquid crystal panels such as liquid crystal televisions, liquid crystal displays, mobile phones, digital cameras, video cameras, portable game machines, car navigation systems, copy machines, printers, fax machines, watches, and microwave ovens.

DESCRIPTION OF SYMBOLS 10 Polarizing film 21 Protective layer 22 Protective layer 30 Adhesive layer 100 Polarizing plate

Claims (7)

A polarizing film having a thickness of 8 μm or less;
A polarizing plate satisfying the following formulas (1) and (2).
Tc ₄₁₀ ≦ 0.2 × Y-8.5 formula (1)
42.5 ≦ Y Formula (2)
(In the formula, Tc ₄₁₀ is an orthogonal transmittance (%) at a wavelength of 410 nm, and Y is a single transmittance (%) measured by a two-degree field of view (C light source) of JIS Z8701 and corrected for visibility. is there.)   The polarizing plate according to claim 1, wherein the polarizing film contains a dye compound having a maximum absorption wavelength of an absorption spectrum in a wavelength region of 380 nm to 480 nm. Further comprising an adhesive layer disposed on at least one side of the polarizing film;
The polarizing plate according to claim 1, wherein the pressure-sensitive adhesive layer contains a dye compound having a maximum absorption wavelength of an absorption spectrum in a wavelength region of 380 nm to 480 nm. A protective layer disposed on at least one side of the polarizing film;
The polarizing plate according to claim 1, wherein the protective layer contains a dye compound having a maximum absorption wavelength of an absorption spectrum in a wavelength region of 380 nm to 480 nm.   5. The dye compound according to claim 2, wherein the dye compound has a maximum absorption wavelength of an absorption spectrum in a wavelength region of 380 nm to 430 nm, and a half width of the absorption spectrum at the maximum absorption wavelength is 10 nm to 60 nm. The polarizing plate as described.   A liquid crystal panel comprising the polarizing plate according to claim 1. A liquid crystal display device comprising the liquid crystal panel according to claim 6.