JP6214502B2 - Manufacturing method of polarizing plate - Google Patents

Description

  The present invention relates to a method for producing a polarizing plate.

Polarizers are used in image display devices (particularly liquid crystal display devices).
As such a polarizing plate, a polarizing plate in which a transparent protective film (for example, a cellulose acylate film or the like) is bonded to one or both sides of a polarizer with an adhesive is used.
In recent years, liquid crystal display devices, particularly liquid crystal display devices for small and medium-sized applications, have been rapidly reduced in thickness. For example, it is required to reduce the thickness of the entire polarizing plate including a hard coat layer to about 100 μm or less. Therefore, there is an urgent need to reduce the thickness of the members (film, polarizer) used.

For example, in Patent Document 1, from the viewpoint of thinning, “a laminate in which a base material layer and a hydrophilic polymer layer are laminated is a stretched laminate in which a stretching treatment is performed, and a hydrophilic polymer layer is formed. Is a polarizing plate containing a stretched laminate in which at least a dichroic substance is adsorbed, and the laminate in which the base material layer and the hydrophilic polymer layer are laminated comprises: The hydrophilic polymer layer is directly laminated, the hydrophilic polymer layer in the stretched laminate has a thickness of 2 to 10 μm, and the base material layer in the stretched laminate has a thickness of 5 to 100 μm. and moisture permeability in the range of less 120g / m 2 / ^24h, the hydrophilic polymer layer functions as a polarizer in the stretched laminate, the base material layer in the stretched laminate is as a transparent protective film for the polarizer A polarizing plate characterized by being used. There has been described ([Claim 1] [0020]).

JP 2011-1000016 A

  When the present inventors examined the polarizing plate described in Patent Document 1, when adsorbing a dichroic substance (such as iodine) on a hydrophilic polymer layer (such as a polyvinyl alcohol film), The substrate layer was also dyed (colored) simultaneously with the hydrophilic polymer layer, and as a result, it became clear that there was a problem that the transmittance of the polarizing plate was lowered.

  Therefore, the present invention provides a method for producing a polarizing plate that can suppress dyeing of a base material layer resulting from a dyeing process and suppress a decrease in transmittance even when the polarizer is thinned. This is the issue.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors use a laminate in which a low moisture-permeable layer, a base material layer, and a hydrophilic polymer layer are laminated in this order as a laminate to be dyed. Thus, even when the polarizer is thinned, it was found that the dyeing of the base material layer can be suppressed and the decrease in the transmittance of the produced polarizing plate can be suppressed, and the present invention has been completed.
That is, it has been found that the above object can be achieved by the following configuration.

[1] A method for producing a polarizing plate for producing a polarizing plate having a polarizer,
By applying a dyeing treatment to the laminate in which the low moisture-permeable layer, base material layer and hydrophilic polymer layer are laminated in this order, and adsorbing the dichroic material to the hydrophilic polymer layer, The manufacturing method of a polarizing plate which has a polarizer formation process which functions a molecular layer as a polarizer.
[2] The method for producing a polarizing plate according to [1], wherein the polarizer forming step is a step of performing a stretching treatment before the dyeing treatment, simultaneously with the dyeing treatment, or after the dyeing treatment.
[3] The method for producing a polarizing plate according to [1], wherein the polarizer forming step is a step of subjecting the laminate to a stretching treatment and then a dyeing treatment.
[4] The moisture permeability of the low moisture-permeable layer is not more than ^{100g / m 2 / 24h, [} 1] the production method of the polarizing plate according to any one of - [3].
[5] The method for producing a polarizing plate according to any one of [1] to [4], wherein the polarizer has a thickness of 0.5 to 30 μm.

According to the present invention, there is provided a method for producing a polarizing plate capable of suppressing dyeing of a base material layer resulting from a dyeing process and suppressing a decrease in transmittance even when the polarizer is thinned. be able to.
In addition, according to this invention, since the base material layer in the laminated body which performs a dyeing | staining process can be utilized as a functional layer (transparent protective film) of a polarizing plate, the manufacturing method of this invention is polarized light which is not thinned. It can also be used effectively for the production of a polarizing plate having a child.

FIG. 1 is a schematic cross-sectional view showing an example of a method for producing a polarizing plate of the present invention. FIG. 2 is a schematic cross-sectional view showing another example of the method for producing a polarizing plate of the present invention.

Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  The method for producing a polarizing plate of the present invention (hereinafter also abbreviated as “production method of the present invention”) is a method for producing a polarizing plate for producing a polarizing plate having a polarizer, and includes a low moisture-permeable layer and a base material layer. In addition, the laminated body in which the hydrophilic polymer layers are laminated in this order is subjected to a dyeing process, and the dichroic substance is adsorbed to the hydrophilic polymer layer, so that the hydrophilic polymer layer functions as a polarizer. It is a manufacturing method of a polarizing plate which has a polarizer formation process.

The manufacturing method of the present invention having such a polarizer forming step suppresses dyeing of the base material layer resulting from the dyeing process and suppresses a decrease in transmittance even when the polarizer is thinned. Can do.
Here, the dyeing solution used in the dyeing treatment generally contains a water-soluble dichroic substance (for example, iodine or organic dye), and this dichroic substance is a water molecule in an aqueous solvent. Together with water molecules, allowing them to enter the film.
Therefore, by reducing the permeability of water molecules by providing a low moisture-permeable layer, the permeability of the dichroic substance that causes dyeing together with the water molecules can also be lowered.
Therefore, in the present invention, a laminate in which a low moisture-permeable layer, a base material layer, and a hydrophilic polymer layer are laminated in this order, in particular, by having a low moisture-permeable layer, moisture in the production environment of the polarizing plate, etc. It is considered that not only the influence was suppressed, but also the transmission of the iodine complex that caused the dyeing was suppressed, and the dyeing of the base material layer during the dyeing process (immersion in the dyeing bath) was suppressed. It is done.

FIG. 1 is a schematic cross-sectional view showing an example of a method for producing a polarizing plate of the present invention.
A laminated body 10 shown in FIG. 1A is a laminated body before dyeing treatment, and is a laminated body having a low moisture-permeable layer 12, a base material layer 14, and a hydrophilic polymer layer 16 in this order. .
On the other hand, the polarizing plate 20 shown in FIG. 1 (B) is an embodiment after the dyeing treatment is performed on the laminate 10 shown in FIG. 1 (A) and the dichroic substance is adsorbed on the hydrophilic polymer layer. The polarizing plate has a low moisture-permeable layer 22, a base material layer (transparent protective film) 24, and a hydrophilic polymer layer (polarizer) 26 adsorbed with a dichroic substance in this order.

FIG. 2 is a schematic cross-sectional view showing another example of the method for producing a polarizing plate of the present invention.
A laminated body 30 shown in FIG. 2A is a laminated body before being subjected to a dyeing process, and includes a first low moisture permeable layer 32, a base material layer 34, a second low moisture permeable layer 38, and hydrophilicity. This is a laminate having the polymer layer 36 in this order.
On the other hand, the polarizing plate 20 shown in FIG. 2 (B) is an embodiment after the dyeing process is performed on the laminate 30 shown in FIG. 2 (A) and the dichroic substance is adsorbed on the hydrophilic polymer layer. The first low-moisture permeable layer 42, the base material layer (transparent protective film) 44, the second low-moisture permeable layer 48, and the hydrophilic polymer layer (polarizer) 46 to which the dichroic substance is adsorbed are arranged in this order. It is the polarizing plate which has.

  Below, in the manufacturing method of this invention, a laminated body, each layer which comprises it, a polarizer formation process, etc. are explained in full detail.

[Laminate]
A laminated body is a laminated body before performing a dyeing | staining process, and is a laminated body which has a low moisture-permeable layer, a base material layer, and a hydrophilic polymer layer in this order.

[Low moisture permeability layer]
Although the said low moisture-permeable layer will not be specifically limited if it is a layer which suppresses the permeability | transmittance of a water molecule, the moisture permeability just before the dyeing process mentioned later (when the extending process mentioned later is given before the dyeing process mentioned later) refers to moisture permeability after stretching treatment. forth.) of preferably less 100g / m ² / 24h, more preferably not more than ^{75g / m 2 / 24h, 50g} / m 2 / 24h or less More preferably. Moreover, it is preferable that a water vapor transmission rate is 0.01 g / m < ² > / 24h or more.
Here, “moisture permeability” refers to an area in an atmosphere at a temperature of 40 ° C. and a relative humidity of 90% according to the method described in “Moisture permeability test method of moisture-proof packaging material (cup method)” of JIS Z 0208: 1976. The amount of water vapor (g / m ² / day) passing through a 1 m ² sample in 24 hours.

  The low moisture permeability layer is a composition containing a compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond in the molecule (hereinafter referred to as “low permeability” from the viewpoint of low moisture permeability, manufacturability, and environmental properties. It is also abbreviated as “a curable composition for a wet layer”.) Or a cyclic polyolefin resin-containing layer, more preferably a cyclic polyolefin resin-containing layer.

<Layer formed from curable composition for low moisture permeable layer>
In the present invention, the layer formed from the curable composition for a low moisture permeable layer has a cyclic aliphatic hydrocarbon group and an unsaturated double bond group in the molecule in order to impart low moisture permeability. And a composition containing a polymerization initiator, a solvent, a fluorine-containing or silicone-based compound, inorganic fine particles, and an inorganic layered compound, if necessary, directly on the substrate layer described later. Or it can form by apply | coating, drying, and hardening through another layer (for example, easily bonding layer etc.). Each component will be described below. In addition, the main component of a composition or a layer means the component which occupies 50 mass% or more of the composition or the layer.

(Compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group in the molecule)
A compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond group in the molecule can function as a binder.
Moreover, this compound can function also as a hardening | curing agent, and it becomes possible to improve the intensity | strength and abrasion resistance of a coating film simultaneously with providing low moisture permeability.
By using such a compound, low moisture permeability and high film strength can be realized. Although the details are not clear, by using a compound having a cycloaliphatic hydrocarbon group in the molecule, a hydrophobic cycloaliphatic hydrocarbon group is introduced into the low moisture-permeable layer, and is hydrophobized. Prevents uptake of molecules and reduces moisture permeability. Moreover, by having an unsaturated double bond group in a molecule | numerator, a crosslinking point density is raised and the diffusion path | route of the water molecule in a low moisture-permeable layer is restrict | limited. Increasing the crosslink point density also has the effect of relatively increasing the density of the cyclic aliphatic hydrocarbon group, making the inside of the low moisture permeable layer more hydrophobic, preventing the adsorption of water molecules, and reducing the moisture permeability. it is conceivable that.
In order to increase the crosslinking point density, the number of unsaturated double bond groups in the molecule is more preferably 2 or more.

The cyclic aliphatic hydrocarbon group is preferably a group derived from an alicyclic compound having 7 or more carbon atoms, more preferably a group derived from an alicyclic compound having 10 or more carbon atoms, and further preferably Is a group derived from an alicyclic compound having 12 or more carbon atoms.
The cycloaliphatic hydrocarbon group is particularly preferably a group derived from a polycyclic compound such as bicyclic or tricyclic.
More preferably, the central skeleton of the compound described in the claims of JP-A No. 2006-215096, the central skeleton of the compound described in JP-A No. 2001-10999, or the skeleton of an adamantane derivative may be used.

  As the cyclic aliphatic hydrocarbon group (including a linking group), a group represented by any one of the following general formulas (I) to (V) is preferable, and the following general formula (I), (II), or (IV) Is more preferable, and a group represented by the following general formula (I) is more preferable.

  In general formula (I), L and L ′ each independently represent a divalent or higher linking group. n represents an integer of 1 to 3.

  In general formula (II), L and L ′ each independently represent a divalent or higher linking group. n represents an integer of 1 to 2.

  In general formula (III), L and L ′ each independently represent a divalent or higher linking group. n represents an integer of 1 to 2.

  In general formula (IV), L and L ′ each independently represent a divalent or higher valent linking group, and L ″ represents a hydrogen atom or a divalent or higher valent linking group.

  In general formula (V), L and L ′ each independently represent a divalent or higher linking group.

  Specific examples of the cyclic aliphatic hydrocarbon group include norbornyl, tricyclodecanyl, tetracyclododecanyl, pentacyclopentadecanyl, adamantyl, diamantanyl and the like.

Examples of the unsaturated double bond group include polymerizable functional groups such as a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, a (meth) acryloyl group and —C (O) OCH═CH ₂ Is preferred. Particularly preferably, a compound containing three or more (meth) acryloyl groups in one molecule described below can be used. The (meth) acryloyl group means a concept including a methacryloyl group or an acryloyl group, and will be described later (meth) acrylic acid, (meth) acryloyl chloride, (meth) acrylic anhydride, (meth) acrylic acid glycidyl, The same applies to the (meth) acrylic resin.

A compound having a cycloaliphatic hydrocarbon group and having 3 or more unsaturated double bond groups in the molecule has the above-described cycloaliphatic hydrocarbon group and the group having an unsaturated double bond as a linking group. It is comprised by connecting via.
As the linking group, a single bond, an alkylene group having 1 to 6 carbon atoms which may be substituted, an amide group which may be substituted at the N-position, a carbamoyl group which may be substituted at the N-position, or an ester group , An oxycarbonyl group, an ether group, and the like, and groups obtained by combining these.

These compounds include, for example, polyols such as diols and triols having the above cyclic aliphatic hydrocarbon groups, and carboxylic acids and carboxylic acid derivatives of compounds having (meth) acryloyl groups, vinyl groups, styryl groups, allyl groups, etc. It can be easily synthesized by a one-step or two-step reaction with an epoxy derivative, an isocyanate derivative or the like.
Preferably, compounds such as (meth) acrylic acid, (meth) acryloyl chloride, (meth) acrylic anhydride, glycidyl (meth) acrylate, and compounds described in WO2012 / 00316A (eg, 1,1-bis ( (Acryloxymethyl) ethyl isocyanate) can be synthesized by reacting with a polyol having the above cyclic aliphatic hydrocarbon group.

  Hereinafter, although the preferable specific example of the compound which has a cyclic aliphatic hydrocarbon group and has an unsaturated double bond group is shown, this invention is not limited to these.

(Polymerization initiator)
The curable composition for a low moisture permeable layer preferably contains a polymerization initiator, and the polymerization initiator is preferably a photopolymerization initiator.
Examples of the photopolymerization initiator include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds , Fluoroamine compounds, aromatic sulfoniums, lophine dimers, onium salts, borate salts, active esters, active halogens, inorganic complexes, coumarins and the like.
Specific examples, preferred embodiments, commercially available products, and the like of the photopolymerization initiator are described in paragraphs [0133] to [0151] of JP-A-2009-098658, and can be suitably used in the present invention as well. it can.

  “Latest UV Curing Technology” {Technical Information Association, Inc.} (1991), p. 159, and “UV Curing System” written by Kiyomi Kato (published by the General Technology Center in 1989), p. Various examples are also described in 65-148 and are useful in the present invention.

  Commercially available photocleavable photoradical polymerization initiators include “Irgacure 651”, “Irgacure 184”, “Irgacure 819”, “Irgacure 907”, “Irgacure 1870” (CGI-403 / Irgacure 184 = manufactured by BASF) 7/3 mixed initiator), “Irgacure 500”, “Irgacure 369”, “Irgacure 1173”, “Irgacure 2959”, “Irgacure 4265”, “Irgacure 4263”, “Irgacure 127”, “OXE01”, etc .; “Kaya Cure DETX-S”, “Kaya Cure BP-100”, “Kaya Cure BDK”, “Kaya Cure CTX”, “Kaya Cure BMS”, “Kaya Cure 2-EAQ”, “Kaya Cure ABQ”, “Kaya Cure CPTX” manufactured by Yakuhin Co., Ltd. "," “Cure EPD”, “Kaya Cure ITX”, “Kaya Cure QTX”, “Kaya Cure BTC”, “Kaya Cure MCA”, etc .; Etc., and combinations thereof are preferred examples.

  The content of the photopolymerization initiator in the curable composition for the low moisture permeable layer is set so that the polymerizable compound contained in the composition is polymerized and the starting point is not increased excessively. 0.5-8 mass% is preferable with respect to the total solid in the composition for coat layer formation, and 1-5 mass% is more preferable.

(solvent)
The curable composition for a low moisture-permeable layer can contain a solvent. As the solvent, various solvents can be used in consideration of the solubility of the monomer, the drying property during coating, the dispersibility of the translucent particles, and the like. Examples of such organic solvents include dibutyl ether, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, anisole, phenetole, dimethyl carbonate, carbonic acid. Methyl ethyl, diethyl carbonate, acetone, methyl ethyl ketone (MEK), diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, propyl acetate, Methyl propionate, ethyl propionate, γ-ptyrolactone, methyl 2-methoxyacetate, methyl 2-ethoxyacetate, ethyl 2-ethoxyacetate, ethyl 2-ethoxypropionate, 2-metho Siethanol, 2-propoxyethanol, 2-butoxyethanol, 1,2-diacetoxyacetone, acetylacetone, diacetone alcohol, methyl acetoacetate, methyl acetoacetate and other methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, cyclohexyl Alcohol, isobutyl acetate, methyl isobutyl ketone (MIBK), 2-octanone, 2-pentanone, 2-hexanone, ethylene glycol ethyl ether, ethylene glycol isopropyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, ethyl carbitol, butyl carbitol , Hexane, heptane, octane, cyclohexane, methylcyclohexane, ethylcyclohexane, benzene, tolu Examples thereof include ene and xylene, and these can be used alone or in combination of two or more.

  When the material constituting the substrate layer described later is a cellulose acylate film, it is preferable to use at least one of dimethyl carbonate, methyl acetate, ethyl acetate, methyl ethyl ketone, acetylacetone, and acetone, either dimethyl carbonate or methyl acetate Is more preferred, and methyl acetate is particularly preferred.

  It is preferable to use a solvent such that the solid content of the curable composition for a low moisture permeable layer is in the range of 20 to 80% by mass, more preferably 30 to 75% by mass, and still more preferably 40 to 70%. % By mass.

(Fluorine-containing or silicone surfactant)
In the curable composition for a low moisture permeable layer, a known fluorine-containing surfactant or silicone-based surfactant can be used as the surfactant.
Preferred embodiments and specific examples of the fluorosurfactant are described in paragraph numbers [0023] to [0080] of JP-A-2007-102206, and similar embodiments and specific examples are also included in the present invention.

  Moreover, as a preferable example of a silicone type surfactant, what has a substituent in the terminal and / or side chain of a compound chain | strand which contains multiple dimethylsilyloxy units as a repeating unit is mentioned. The compound chain containing dimethylsilyloxy as a repeating unit may contain a structural unit other than dimethylsilyloxy. The substituents may be the same or different, and a plurality of substituents are preferable. Examples of preferable substituents include groups including a polyether group, an alkyl group, an aryl group, an aryloxy group, an aryl group, a cinnamoyl group, an oxetanyl group, a fluoroalkyl group, a polyoxyalkylene group, and the like.

  Although there is no restriction | limiting in particular in a number average molecular weight, It is preferable that it is 100,000 or less, It is more preferable that it is 50,000 or less, It is especially preferable that it is 1000-30000, It is most preferable that it is 1000-20000.

  Examples of preferable silicone compounds include, for example, “X-22-174DX”, “X-22-2426”, “X22-164C”, “X-22-176D”, manufactured by Shin-Etsu Chemical Co., Ltd. ( “Product name”; “FM-7725”, “FM-5521”, “FM-6621”, (product name) manufactured by Chisso Corporation; “DMS-U22”, “RMS-033” manufactured by Gelest (Product name); “SH200”, “DC11PA”, “ST80PA”, “L7604”, “FZ-2105”, “L-7604”, “Y-7006”, “Toray Dow Corning Co., Ltd.” "SS-2801", (above product name); "TSF400" (product name); manufactured by Momentive Performance Materials Japan, but not limited to these .

  Such a silicone-based or fluorine-containing surfactant is preferably contained in an amount of 0.01 to 0.5% by mass in the total solid content of the curable composition for a low moisture-permeable layer, 0.3 mass% is more preferable.

(Inorganic fine particles)
The curable composition for a low moisture permeable layer preferably contains inorganic fine particles in order to further reduce the moisture permeability of the low moisture permeable layer.
As the inorganic fine particles, inorganic oxide fine particles and magnesium fluoride are used. Among these, silica fine particles are particularly preferable in terms of refractive index, dispersion stability, and cost.
The average particle size (primary particle size) of the inorganic fine particles is preferably 30 to 100 nm, more preferably 35 to 90 nm, and still more preferably 40 to 85 nm.
When the average particle size of the inorganic fine particles is 30 to 100 nm, the moisture permeability reduction effect is preferably exhibited.

In addition, regarding the mechanism by which inorganic fine particles having an average particle size of 30 nm or more and 100 nm or less exhibit a moisture permeability reduction effect, the inventors consider as follows.
When a water vapor partial pressure difference is made between one surface and the other surface of a film having a low moisture permeable layer, water molecules pass through the low moisture permeable layer as a driving force. When inorganic fine particles are present in the low moisture-permeable layer, water molecules cannot pass through the inorganic fine particles, and it is considered that the moisture permeability reduction effect is produced by limiting the region that can pass through the layer.
On the other hand, the surface of the inorganic fine particles is covered with a hydroxyl group, water molecules are easily adsorbed, and water molecules are likely to be present in the low moisture-permeable layer. In a steady state, it is considered that water molecules repeatedly adsorb and desorb on the surface of the inorganic fine particles in the low moisture-permeable layer. When the same amount of inorganic fine particles is contained in the low moisture-permeable layer, if the average particle size of the inorganic fine particles is less than 30 nm, the total surface area of the inorganic fine particles is increased, and the average distance between the inorganic fine particles is further reduced. Therefore, it is considered that the above moisture permeability reduction effect that water molecules cannot pass through the inorganic fine particles cannot be sufficiently exhibited.
Further, if the average particle size of the inorganic fine particles is larger than 100 nm, it becomes easy to form a gap in the layer such as between the inorganic fine particles and the binder, and it is considered that the moisture permeability is increased by passing water molecules through the gap. .

  The inorganic fine particles may be either crystalline or amorphous, and may be monodispersed particles or aggregated particles as long as a predetermined particle size is satisfied, but is preferably monodispersed. The shape may be an indeterminate shape, or may be a porous particle or a hollow particle. However, since it is preferable that water molecules are less adsorbed, a particle having a spherical diameter and having no cavity inside is most preferable.

Two or more inorganic fine particles having different average particle diameters can be used in combination.
Here, the average particle diameter of the inorganic fine particles can be obtained from a known method such as an electron micrograph or a BET method. In the present invention, the average particle diameter is obtained by the BET method.

The inorganic fine particles are preferably surface-treated by a conventional method, and are preferably surface-treated (surface-modified) with a silane coupling agent.
In particular, the surface of the inorganic fine particles is preferably treated with a hydrolyzate of an organosilane compound and / or a partial condensate thereof in order to improve dispersibility in the curable composition for a low moisture permeable layer. In the treatment, it is more preferable to use either an acid catalyst or a metal chelate compound or both. The method for treating the surface of the inorganic fine particles is described in paragraphs [0046] to [0076] of JP-A-2008-242314, and the organosilane compound, the siloxane compound, and the solvent for the surface treatment described in the document. Surface treatment catalysts, metal chelate compounds, and the like can also be suitably used in the present invention.

  The content of the inorganic fine particles is preferably 10 to 80% by mass, and preferably 15 to 75% by mass with respect to the total solid content of the curable composition for a low moisture permeable layer in order to obtain a moisture permeability lowering effect. More preferred is 20 to 70% by mass. When it is at least the lower limit of the above range, a moisture permeability reduction effect is obtained, and when it is at most the upper limit, the problem of an increase in moisture permeability due to the generation of voids hardly occurs.

(Inorganic layered compound)
The curable composition for a low moisture permeable layer preferably contains an inorganic layered compound in order to further reduce the moisture permeability of the low moisture permeable layer.
Since the inorganic layered compound has a hydrophilic surface, it is preferably subjected to an organic treatment.

The inorganic layered compound is an inorganic compound having a structure in which unit crystal layers are laminated and exhibiting a property of swelling or cleaving by coordinating or absorbing a solvent between the layers. Examples of such inorganic compounds include swellable hydrous silicates such as smectite group clay minerals (montmorillonite, saponite, hectorite, etc.), palm curite group clay minerals, kaolinite group clay minerals, phyllosilicates (mica). Etc.). In addition, a synthetic inorganic layered compound is also preferably used. Examples of the synthetic inorganic layered compound include synthetic smectite (hectorite, saponite, stevensite, etc.), synthetic mica, etc., preferably smectite, montmorillonite, mica, montmorillonite, mica. Is more preferable. As an inorganic layered compound that can be used as a commercial product, MEB-3 (Synthetic mica aqueous dispersion manufactured by Corp Chemical Co., Ltd.), ME-100 (Synthetic mica manufactured by Corp Chemical Co., Ltd.), S1ME (manufactured by Corp Chemical Co., Ltd.) Synthetic mica), SWN (Synthetic smectite manufactured by Corp Chemical Co., Ltd.), SWF (Synthetic smectite manufactured by Corp Chemical Co., Ltd.), Kunipia F (Purified bentonite manufactured by Kunimine Chemical Co., Ltd.), Bengel (Purified by Hojun Co., Ltd.) Bentonite), Wengel HV (Purified bentonite manufactured by Hojung Co., Ltd.), Wenger FW (Purified bentonite manufactured by Hojun Co., Ltd.), Wenger Bright 11 (Purified bentonite manufactured by Hojun Co., Ltd.), Wenger Bright 23 (Purified manufactured by Hojun Co., Ltd.) Bentonite), Wenger Bright 25 (Hojung Co., Ltd.) Purification bentonite), Wenger A (HOJUN Co. purification bentonite), can be used Wenger 2M (HOJUN Co. purified bentonite) or the like.
Such inorganic layered compounds are preferably those obtained by subjecting these inorganic layered compounds to organic treatment.

  The inorganic layered compound is preferably finely divided from the viewpoint of achieving both low moisture permeability and adhesion between the substrate and the low moisture permeability layer. The inorganic layered compound subjected to the fine particle treatment is usually plate-shaped or flat, and the planar shape is not particularly limited, and may be an amorphous shape. The average particle size (planar average particle size) of the inorganic layered compound that has been microparticulated is preferably, for example, 0.1 to 10 μm, more preferably 0.1 to 8 μm, and particularly preferably 0.1 to 6 μm.

<Cyclic polyolefin-based resin-containing layer>
In the present invention, the cyclic polyolefin resin-containing layer is a layer containing a cyclic polyolefin resin as a main component. In addition, the main component of a composition or a layer means the component which occupies 50 mass% or more of the composition or the layer.

(Cyclic polyolefin resin)
The cyclic polyolefin-based resin represents a polymer resin having a cyclic olefin structure.
Examples of cyclic polyolefin resins include (1) norbornene polymers, (2) monocyclic olefin polymers, (3) cyclic conjugated diene polymers, and (4) vinyl alicyclic hydrocarbon polymers. And hydrides of (1) to (4).
As the polymer having a cyclic olefin structure preferably used in the present invention, a cyclic polyolefin resin which is an addition (co) polymer containing at least one repeating unit represented by the following general formula (II) and if necessary The cyclic polyolefin resin which is an addition (co) polymer further comprising at least one repeating unit represented by formula (I). Further, a ring-opening (co) polymer containing at least one cyclic repeating unit represented by the general formula (III) can also be suitably used.

In formulas (I) to (III), m represents an integer of 0 to 4. R ^{1 to} R ⁶ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, X ^{1 to} X ³ and Y ^{1 to} Y ³ are a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a halogen atom, and a halogen atom. substituted hydrocarbon group having 1 to 10 carbon _{atoms, - (CH 2) n COOR} 11, - (CH 2) n OCOR 12, - (CH 2) n NCO, - (CH 2) n NO 2, - ( _{CH 2) n CN, - (} CH 2) n CONR 13 R 14, - (CH 2) n NR 13 R 14, - (CH 2) n OZ, - (CH 2) n W, or X ¹ and Y ¹ Alternatively, (—CO) ₂ O and (—CO) ₂ NR ¹⁵ composed of X ² and Y ² or X ³ and Y ³ are shown. R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , and R ¹⁵ are hydrogen atoms, hydrocarbon groups having 1 to 20 carbon atoms, Z is a hydrocarbon group or a hydrocarbon group substituted with a halogen, and W is SiR ¹⁶ _p. D _3-p (R ¹⁶ is a hydrocarbon group having 1 to 10 carbon atoms, D is a halogen atom, —OCOR ¹⁶ or —OR ¹⁶ , p is an integer of 0 to 3), n is an integer of 0 to 10 Show.

Norbornene polymer hydrides can also be preferably used. JP-A-1-240517, JP-A-7-196636, JP-A-60-26024, JP-A-62-19801, JP-A-2003-1159767. As disclosed in Japanese Patent Application Laid-Open No. 2004-309979 or the like, the polycyclic unsaturated compound is hydrogenated after addition polymerization or metathesis ring-opening polymerization. In the norbornene-based polymer used in the present invention, R ^{3 to} R ⁶ are preferably a hydrogen atom or —CH _{3, and} more preferably a hydrogen atom from the viewpoint of low moisture permeability. X ³ and Y ³ are preferably a hydrogen atom, Cl, and —COOCH _{3, and} more preferably a hydrogen atom from the viewpoint of low moisture permeability. Other groups are appropriately selected. m is preferably 0 or 1.

  Furthermore, norbornene-based addition (co) polymers can also be preferably used, and are disclosed in JP-A No. 10-7732, JP 2002-504184 A, US Published Patent No. 20020042157A1 or WO 2004 / 070463A1. It can be obtained by addition polymerization of norbornene-based polycyclic unsaturated compounds. If necessary, norbornene-based polycyclic unsaturated compounds and ethylene, propylene, butene; conjugated dienes such as butadiene and isoprene; nonconjugated dienes such as ethylidene norbornene; acrylonitrile, acrylic acid, methacrylic acid, maleic anhydride It is also possible to carry out addition polymerization with linear diene compounds such as acid, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate and vinyl chloride. Among these, a copolymer with ethylene is preferable. As the norbornene-based addition (co) polymer, for example, TOPAS6013 manufactured by Polyplastics Co., Ltd. can be used.

The cyclic polyolefin resin-containing layer is a layer formed by curing a curable composition containing a cyclic polyolefin resin (hereinafter also abbreviated as “coating composition for forming a cyclic polyolefin resin-containing layer”). Is preferred.
The coating composition for forming a cyclic polyolefin-based resin-containing layer may further contain a polymerization initiator, an inorganic layered compound, a solvent, etc., as necessary, similarly to the above-described curable composition for a low moisture-permeable layer. In particular, the following organic solvents are preferably used as the solvent.

(Organic solvent)
Examples of organic solvents that can be used in the coating composition for forming a cyclic polyolefin-based resin layer include chain aliphatic hydrocarbon solvents such as n-pentane, n-hexane, n-heptane, liquid paraffin, and mineral spirits, cyclopentane, Cyclohexane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, ethylcyclohexane, diethylcyclohexane, decahydronaphthalene, dicycloheptane, tricyclodecane, hexahydroindene, cyclooctane and other alicyclic hydrocarbon solvents, benzene, toluene, xylene Aromatic hydrocarbon solvents such as indene, tetrahydronaphthalene, etc., hydrocarbon solvents having alicyclic and aromatic rings, nitrogen-containing hydrocarbon solvents such as nitromethane, nitrobenzene, acetonitrile, etc. Oxygenated hydrocarbon solvents such as ether and tetrahydrofuran, chlorine solvents such as dichloromethane and chloroform, methanol, ethanol, isopropanol, n-butyl alcohol, cyclohexyl alcohol, 2-ethyl-1-hexanol, 2-methyl-1-hexanol, Alcohol solvents such as 2-methoxyethanol, 2-propoxyethanol, 2-butoxyethanol, diacetone alcohol, carbonate solvents such as dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, methyl ethyl carbonate, methyl n-propyl carbonate, Ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, 2-ethoxypropion Esters such as ethyl, methyl acetoacetate, ethyl acetoacetate, methyl 2-methoxyacetate, methyl 2-ethoxyacetate, ethyl 2-ethoxyacetate, ethylene glycol ethyl ether, ethylene glycol isopropyl ether, ethylene glycol butyl ether, propylene glycol methyl Ether solvents such as ether, dibutyl ether, dimethoxyethane, diethoxyethane, tetrahydrofuran, anisole, phenetole, acetone, 1,2-diacetoxyacetone, acetylacetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone , Cyclohexanone, methylcyclohexanone, methyl isobutyl ketone, 2-octanone, 2-pentanone, 2-hexanone, etc. A ketone solvent etc. are mentioned, It can use individually by 1 type or in combination of 2 or more types.

<Thickness of low moisture permeable layer>
The thickness of the low moisture permeable layer is preferably 1 to 20 μm, more preferably 2 to 18 μm, and particularly preferably 3 to 17 μm.
The low moisture-permeable layer may be a single layer or a plurality of layers.
Further, the low moisture permeable layer preferably has a moisture permeable hard coat layer function, an antireflection function, an antifouling function, and the like.

<Production method of low moisture permeability layer>
The method for producing the low moisture-permeable layer is not particularly limited. For example, the method for producing the low moisture-permeable layer as co-casting and co-extrusion with a material constituting the base material layer to be described later; And the like. Among them, the latter method is preferable.

[Base material layer]
As said base material layer, what was conventionally used as a transparent protective film of a polarizer can be used.
As a material constituting the base material layer, for example, it is preferable to use a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, stretchability, and the like.
Specific examples of such thermoplastic resins include: cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone resins; polysulfone resins; polycarbonate resins; polyamide resins; Polyolefin resins such as polypropylene and ethylene / propylene copolymers; cyclic polyolefin resins having a cyclo or norbornene structure (norbornene resins); (meth) acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins; and mixtures thereof And the like.

Moreover, as a material of the said base material layer, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007), for example, (A) thermoplastic resin which has a substituted and / or unsubstituted imide group in a side chain And (B) a film of a resin composition containing a substituted and / or unsubstituted phenyl and a thermoplastic resin having a nitrile group in the side chain.
Specifically, a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer may be mentioned.
As the film, a film made of a mixed extruded product of the resin composition or the like can be used. Since these films have a small phase difference and a small photoelastic coefficient, problems such as unevenness due to the distortion of the polarizing plate can be eliminated, and since the moisture permeability is small, the humidification durability is excellent.

Moreover, the said base material layer may contain 1 or more types of arbitrary appropriate additives other than the material mentioned above. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent.
Moreover, it is preferable that content of the said thermoplastic resin in the said base material layer is 50-100 mass%, It is more preferable that it is 50-99 mass%, It is further that it is 60-98 mass%. 70 to 97% by mass is particularly preferable. When the content of the thermoplastic resin in the base material layer is 50% by mass or more, high transparency and the like inherent in the thermoplastic resin can be sufficiently exhibited.

The substrate layer, the moisture permeability of the preceding dyeing process to be described later of preferably less 120g / m ² / 24h, more preferably not more than ^{80g / m 2 / 24h, 20g} / m 2 / 24h More preferably, it is as follows.
Moisture permeability, is not more than 120g / m ² / 24h, in the course of dyeing to be described later, it is possible to further suppress the staining of the substrate layer, is possible to further suppress a decrease in the transmittance of the polarizing plate it can.

Moisture permeability of the base material layer in the laminate, can be adjusted by the thickness of the base layer, low moisture permeability described above in thinner thickness: To satisfy (moisture permeability less 120g / m ² / 24h) is It is preferable to use a low moisture-permeable material as the base material layer.
As the low moisture permeability material, among the resins exemplified above, polycarbonate resin, polyarylate resin, polyester resin, polyamide resin, polyolefin resin, cyclic olefin resin, (meth) acrylic resin, or a mixture thereof can be used. It is preferable to use it.

  In the present invention, it is preferable to use at least one selected from the group consisting of a polyester resin and a (meth) acrylic resin from the viewpoint of low moisture permeability, as the material for the base material layer.

<Polyester resin>
The polyester resin as the material for the base material layer is not particularly limited, and a conventionally known polyester resin can be used.
Specific examples of the polyester resin include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate. Among these, it is particularly preferable to use polyethylene terephthalate from the viewpoint of cost and mechanical strength.

<(Meth) acrylic resin>
The (meth) acrylic resin as the material for the base material layer is not particularly limited, and a conventionally known (meth) acrylic resin can be used. The (meth) acrylic resin is a concept including a methacrylic resin or an acrylic resin, and includes an acrylate / methacrylate derivative, in particular, an acrylate ester / methacrylate ester (co) polymer.
The (meth) acrylic resin also includes a (meth) acrylic polymer having a ring structure in the main chain, in addition to the methacrylic resin and the acrylic resin, and has a polymer having a lactone ring and a succinic anhydride ring. It includes a maleic anhydride polymer, a polymer having a glutaric anhydride ring, and a glutarimide ring-containing polymer.

  In the present invention, examples of the (meth) acrylic resin include (meth) acrylic resins described in paragraphs [0033] to [0038] of Patent Document 1 (Japanese Patent Application Laid-Open No. 2011-1000016), and Japanese Patent Application Laid-Open No. 2010. Acrylic resins and copolymer components described in paragraphs [0033] to [0063] of JP-A-079175 can be used as appropriate.

<Thickness of base material layer>
The thickness of the base material layer can be determined as appropriate, but in general, from the viewpoint of workability such as strength and handleability and thin layer properties, it is preferably about 1 to 500 μm, and preferably 1 to 300 μm. Is more preferable, it is still more preferable that it is 5-200 micrometers, and it is especially preferable that it is 5-150 micrometers.
On the other hand, the thickness of the base material layer (base material layer after stretching) in the stretched laminate (hereinafter also referred to as “stretched laminate”) when the stretching treatment described below is performed before the dyeing treatment described below. Is preferably about 5 to 100 μm, more preferably 5 to 60 μm, and still more preferably 5 to 40 μm, from the viewpoint of workability such as strength and handleability. The thickness of the base material layer in the stretched laminate is determined by the thickness of the base material layer before stretching and the stretch ratio. In general, since the moisture permeability is proportional to the reciprocal of the thickness, the moisture permeability of the base material layer of the stretched laminate is controlled by adjusting the thickness of the base material layer before stretching and the draw ratio so that the moisture permeability is within the above range. It can be determined by controlling.

<Preparation method of base material layer>
Examples of the method for producing the base material layer include conventionally known film forming methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Of these film forming methods, the melt extrusion method is particularly suitable.

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

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

[Hydrophilic polymer layer]
Examples of the hydrophilic polymer used for forming the hydrophilic polymer layer include polyvinyl alcohol materials. Examples of the polyvinyl alcohol material include polyvinyl alcohol and derivatives thereof. 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, alkyl esters thereof, acrylamide and the like. can give. The degree of polymerization of polyvinyl alcohol is preferably about 100 to 10,000, and more preferably 1,000 to 10,000. A saponification degree of about 80 to 100 mol% is generally used. In addition to the above, examples of the hydrophilic polymer include partially saponified ethylene / vinyl acetate copolymer, dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. As the hydrophilic polymer, it is preferable to use polyvinyl alcohol among polyvinyl alcohol materials.

  In the said polyvinyl alcohol-type resin, additives, such as a plasticizer and surfactant, can also be contained. 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 mass or less in the polyvinyl alcohol resin.

<Thickness of hydrophilic polymer layer>
In general, the thickness of the hydrophilic polymer layer is preferably about 1 to 50 μm, and more preferably 2 to 30 μm.
On the other hand, the thickness of the hydrophilic polymer layer in the stretched laminate is preferably 0.5 to 30 μm, more preferably 1 to 20 μm, from the viewpoint of emphasizing the use of the polarizer as a thin film. More preferably, it is 2-10 micrometers. In addition, the thickness of the hydrophilic polymer layer in the stretched laminate is the above-described thickness due to stretching or shrinkage caused by the stretching treatment.

  Here, the measurement of the thickness of the hydrophilic polymer layer in a laminated body and an extending | stretching laminated body can be measured after peeling a hydrophilic polymer layer from a base material layer. The thickness is measured with a thickness gauge or the like.

<Method for producing hydrophilic polymer layer>
As a method for producing the hydrophilic polymer layer, for example, the above-described base material layer, which is not provided with the low moisture permeable layer, is directly or other layer (for example, the second low moisture permeable layer or easy adhesion). It can be produced by applying an aqueous solution containing a hydrophilic polymer via a layer, etc. and then drying.
The aqueous solution can be prepared by dissolving a powder of a hydrophilic polymer or a pulverized product or a cut product of a hydrophilic polymer film in appropriately heated water (hot water).
In addition, the above aqueous solution is applied by appropriately selecting a roll coating method such as a wire bar coating method, reverse coating or gravure coating, a spin coating method, a screen coating method, a fountain coating method, a dipping method or a spray method. it can.
In addition, it is preferable that drying temperature is 50-200 degreeC normally, and it is more preferable that it is 80-150 degreeC. The drying time is usually preferably about 5 to 30 minutes.

[Other layers]
The laminated body may have other layers in addition to the above-described low moisture-permeable layer, base material layer, and hydrophilic polymer layer.
Other layers include, for example, an optional second low moisture-permeable layer (see FIG. 2 (A) -reference numeral 38) provided between the base material layer and the hydrophilic polymer layer, and the base material layer and the low-permeability layer. Examples thereof include an optional easy adhesion layer provided between the wet layer and the hydrophilic polymer layer.

As the second low moisture-permeable layer, a layer similar to the above-described low moisture-permeable layer can be used.
Moreover, as said easily bonding layer, when using (meth) acrylic resin as said base material layer, what was formed with the easily bonding layer composition containing a urethane resin and microparticles | fine-particles is mentioned, for example. When a polyester resin is used as the substrate layer, 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 And the like formed by, for example.
By forming the easy-adhesion layer, the adhesion between the base material layer and the low moisture-permeable layer or hydrophilic polymer layer is improved.

[Polarizer formation process]
The production method of the present invention includes a polarizer forming step in which a laminate is subjected to a dyeing process and a dichroic substance is adsorbed to the hydrophilic polymer layer, thereby causing the hydrophilic polymer layer to function as a polarizer. .
In the production method of the present invention, the stretching treatment is preferably performed before, simultaneously with, or after the dyeing treatment, and since the orientation of the dichroic substance adsorbed on the hydrophilic polymer layer becomes good, the dyeing treatment is performed. It is more preferable to perform a stretching process before the dyeing, and it is more preferable to perform a stretching process before and after the dyeing process.

The stretching treatment is preferably performed by uniaxial stretching.
Uniaxial stretching can employ either longitudinal stretching performed in the longitudinal direction of the laminate or transverse stretching performed in the width direction of the laminate. In the present invention, it is preferably performed by transverse stretching. In transverse stretching, the film can be contracted in the longitudinal direction while stretching in the width direction. Examples of the transverse stretching method include a fixed end uniaxial stretching method in which one end is fixed via a tenter, and a free end uniaxial stretching method in which one end is not fixed. Examples of the longitudinal stretching method include an inter-roll stretching method, a compression stretching method, and a stretching method using a tenter. The stretching process can be performed in multiple stages. The stretching treatment can be performed by performing biaxial stretching, oblique stretching, or the like.

  In addition, as the stretching treatment, either a wet stretching method or a dry stretching method can be adopted, but in the present invention, the dry stretching method is used because the temperature range when stretching the laminate can be set wide. preferable. In the dry stretching method, it is usually preferable to perform the stretching treatment in a state where the laminate is heated to about 50 to 200 ° C., and the heating temperature is more preferably 80 to 180 ° C., and 100 to 160 ° C. Is more preferable.

  In the stretching treatment, the total length of the laminate is preferably 1.5 to 17 times, more preferably 1.5 to 10 times the original length of the laminate. More preferably, it is ˜8 times. The total draw ratio refers to a cumulative draw ratio including stretching in those steps when stretching is involved in a process other than the stretching process. The total draw ratio is appropriately determined in consideration of the draw ratio in other steps. When the total draw ratio is low, the orientation is insufficient and it is difficult to obtain a polarizer having high optical properties (polarization degree). On the other hand, if the total draw ratio is too high, stretch breakage is likely to occur, and the polarizer becomes too thin, which may reduce the workability in the subsequent process.

The dyeing process is performed by adsorbing the dichroic substance to the hydrophilic polymer layer in the laminate.
Here, the dichroic substance is preferably a water-soluble dichroic substance, and examples thereof include iodine and organic dyes.
Organic dyes include, for example, Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B , Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue , Direct First Orange S, First Black and the like.
These dichroic substances may be used alone or in combination of two or more.

Moreover, it is preferable to perform a dyeing | staining process by immersing a laminated body in the solution (dyeing solution) containing a dichroic substance, for example.
As the staining solution, a solution in which a dichroic substance is dissolved in a solvent can be used.
As the solvent, water is generally used, but an organic solvent compatible with water may be further added. The concentration of the dichroic substance is preferably in the range of 0.01 to 10% by mass, more preferably in the range of 0.02 to 7% by mass, and 0.025 to 5% by mass. Is particularly preferred.

Further, when iodine is used as the dichroic substance, it is preferable to further add an iodide because the dyeing efficiency can be further improved.
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. The addition ratio of these iodides is preferably 0.01 to 10% by mass and more preferably 0.1 to 5% by mass in the dyeing solution. Among these, it is preferable to add potassium iodide, and the ratio (weight ratio) of iodine to potassium iodide is preferably in the range of 1: 5 to 1: 100, and 1: 6 to 1:80. More preferably, it is in the range of 1: 7 to 1:70.

  The immersion time of the laminate in the dyeing solution is not particularly limited, but usually it is preferably in the range of 15 seconds to 5 minutes, more preferably 1 minute to 3 minutes. Moreover, it is preferable that it is in the range of 10-60 degreeC, and, as for the temperature of a dyeing | staining solution, it is more preferable that it exists in the range of 20-40 degreeC.

The polarizer forming step in the production method of the present invention can be subjected to a crosslinking treatment in addition to the above-described dyeing treatment and arbitrary stretching treatment.
The crosslinking treatment can be performed, for example, by immersing the laminate in a solution containing a crosslinking agent (crosslinking solution).
A conventionally known substance can be used as the crosslinking agent. Examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. These may be used alone or in combination of two or more.

As the crosslinking solution, a solution in which a crosslinking agent is dissolved in a solvent can be used.
As the solvent, for example, water can be used, but an organic solvent compatible with water may be further included. Although the density | concentration of the crosslinking agent in the said solution is not limited to this, It is preferable to exist in the range of 1-10 mass%, and it is more preferable that it is 2-6 mass%.

  Iodide may be added to the crosslinking solution from the viewpoint that uniform characteristics in the plane of the polarizer can be obtained. 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. The content is preferably 0.05 to 15% by mass, and more preferably 0.5 to 8% by mass.

  The immersion time of the laminate in the crosslinking solution is usually preferably 15 seconds to 5 minutes, and more preferably 30 seconds to 3 minutes. Moreover, it is preferable that the temperature of a bridge | crosslinking solution exists in the range of 10-60 degreeC, and it is more preferable that it exists in the range of 20-50 degreeC.

  Furthermore, the crosslinking treatment can also be performed using a method of coating or spraying the crosslinking solution, similarly to the dyeing treatment. In the crosslinking treatment, the crosslinking treatment and the dyeing treatment can be simultaneously performed by blending the crosslinking agent in the dyeing solution. Moreover, you may perform a crosslinking process with an extending | stretching process.

The polarizer formation process in the manufacturing method of this invention can perform a metal ion process other than the process mentioned above.
The metal ion treatment is performed by immersing the laminate in an aqueous solution containing a metal salt. By the metal ion treatment, various metal ions can be contained in the hydrophilic polymer layer of the laminate.

  As metal ions, metal ions of transition metals such as cobalt, nickel, zinc, chromium, aluminum, copper, manganese, and iron are particularly preferably used in terms of color tone adjustment and durability. Among these metal ions, zinc ions are preferable from the viewpoints of color tone adjustment and heat resistance. Examples of the zinc salt include zinc halides such as zinc chloride and zinc iodide, zinc sulfate, and zinc acetate.

  A metal salt solution is used for the metal ion impregnation treatment. The concentration of zinc ions in the metal salt solution is preferably about 0.1 to 10% by mass, and more preferably 0.3 to 7% by mass. In addition, it is preferable to use an aqueous solution containing an iodide such as potassium iodide as the metal salt solution because it is easy to impregnate metal ions. The iodide concentration in the metal salt solution is preferably about 0.1 to 10% by mass, and more preferably 0.2 to 5% by mass.

  In the metal ion impregnation treatment, the temperature of the metal salt solution is usually preferably about 15 to 85 ° C, and more preferably 25 to 70 ° C. Further, the immersion time is usually preferably about 1 to 120 seconds, and more preferably 3 to 90 seconds. The stage of the metal ion impregnation treatment is not particularly limited, and it may be carried out simultaneously with the dyeing treatment and / or the crosslinking treatment in the presence of a zinc salt in the dyeing solution and / or the crosslinking solution. It can also be performed simultaneously with the stretching treatment.

  After the above treatment is performed, the obtained laminate can be subjected to a washing treatment. The washing treatment can be performed with an iodide solution such as potassium iodide. The iodide concentration in the iodide solution is usually preferably about 0.5 to 10% by mass, more preferably 0.5 to 8% by mass, and further preferably 1 to 6% by mass. preferable.

  In the washing treatment with an iodide solution, the treatment temperature is usually preferably about 15 to 60 ° C, more preferably 25 to 40 ° C. The immersion time is usually preferably about 1 to 120 seconds, and more preferably 3 to 90 seconds. The stage of the washing treatment with the iodide solution is not particularly limited as long as it is before the drying treatment.

  Further, as a cleaning process, a water cleaning process can be performed. A water washing process can be normally performed by immersing the said extending | stretching laminated body in pure waters, such as ion-exchange water and distilled water. The water washing temperature is usually preferably from 5 to 50 ° C, more preferably from 10 to 45 ° C, and still more preferably from 15 to 40 ° C. The immersion time is usually preferably 10 to 300 seconds, and more preferably 20 to 240 seconds.

  After the cleaning process, a drying process can be performed. Arbitrary appropriate methods (For example, natural drying, ventilation drying, heat drying) can be employ | adopted for a drying process. For example, in the case of heat drying, the drying temperature is usually preferably about 20 to 80 ° C., and the drying time is usually preferably about 1 to 10 minutes.

  A polarizing plate produced by the production method of the present invention (hereinafter referred to as “polarizing plate of the present invention”) has a low moisture-permeable layer on one side of a base material layer and a hydrophilic polymer layer ( A polarizer). In addition, a base material layer can be used as it is as a transparent protective film of a polarizer.

  The polarizing plate of the present invention can be used as an optical film laminated with another optical layer in practical use. The optical layer is not particularly limited. For example, for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), and a viewing angle compensation film. One or more optical layers that may be used can be used. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate or a semi-transmissive reflecting plate is further laminated on the polarizing plate of the present invention, an elliptical polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on the polarizing plate. A wide viewing angle polarizing plate obtained by further laminating a viewing angle compensation film on a plate or a polarizing plate, or a polarizing plate obtained by further laminating a brightness enhancement film on the polarizing plate is preferable.

  The polarizing plate or the optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing plate or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses the polarizing plate or optical film by invention, and it can apply conventionally. As the liquid crystal cell, any type such as a TN type, STN type, π type, VA type, IPS type, or the like can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which a polarizing plate or an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the polarizing plate or optical film by this invention can be installed in the one side or both sides of a liquid crystal cell. When providing a polarizing plate or an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  Hereinafter, the present invention will be described in more detail based on examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.

  Here, the phase difference value was measured with respect to a value of a wavelength of 590 nm using a phase difference meter based on the parallel Nicol rotation method (manufactured by Oji Scientific Instruments, product name “KOBRA21-ADH”), nx, From the values of ny and nz and the film thickness (d), the front phase difference Re, the thickness direction phase difference Rth and Nz were obtained. [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. ].

The moisture permeability is a sample having an area of 1 m ^{2 in} an atmosphere at a temperature of 40 ° C. and a relative humidity of 90% in accordance with the method described in “Moisture permeability test method for moisture-proof packaging materials (cup method)” of JIS Z 0208: 1976. Was measured for the amount of water vapor (g / m ² / day) passing through for 24 hours.

[Example 1]
[Preparation of aqueous solution containing hydrophilic polymer]
Kuraray Co., Ltd. polyvinyl alcohol film (average polymerization degree 2400, saponification degree 99 mol%, trade name: VF-PS2400) is cut into small pieces of 5 mm or less on one side and dissolved in 95 ° C hot water A polyvinyl alcohol aqueous solution having a concentration of 10% by mass was prepared.

(Preparation of base material layer)
As the substrate layer, an acrylic resin film (lactonized polymethyl methacrylate film, Re = 2 nm, Rth = 0 nm) having a thickness of 80 μm was used.
This acrylic resin film is a (meth) acrylic resin having a lactone ring structure [weight ratio of copolymerization monomer: methyl methacrylate / 2- (hydroxymethyl) methyl acrylate = 8/2; lactone cyclization rate of about 100 %] A mixture of 90 parts by mass and 10 parts by mass of acrylonitrile-styrene (AS) resin {Toyo AS AS20, manufactured by Toyo Styrene Co., Ltd.} (manufactured by Nippon Shokubai Co., Ltd.) was melt-extruded, and the length 2 Obtained by stretching by a factor of 0.0.
In Table 1 below, the acrylic resin film as the low moisture permeable layer is simply referred to as “acrylic”.

[Preparation of composition for forming a low moisture-permeable layer]
A composition for forming a low moisture-permeable layer was prepared as shown below.

<Composition of Composition B-1 for Forming Low Moisture Permeability Layer>
-A-DCP (100%): tricyclodecane dimethanol dimethacrylate [manufactured by Shin-Nakamura Chemical Co., Ltd.] 97.0 parts by mass-Irgacure 907 (100%): polymerization initiator [manufactured by BASF] 3.0 Mass parts SP-13 (leveling agent) represented by the following formula: 0.04 mass parts MEK (methyl ethyl ketone): 81.8 mass parts

(Production of laminate)
<Formation of a low moisture permeable layer>
A die coat using the slot die described in Example 1 of JP-A-2006-122889 using the low moisture-permeable layer forming composition B-1 on one surface of the acrylic resin film (base material layer). The coating was carried out by the above method at a conveyance speed of 30 m / min and dried at 60 ° C. for 150 seconds.
Thereafter, using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) with an oxygen concentration of about 0.1% under a nitrogen purge, ultraviolet rays with an illuminance of 400 mW / cm ² and an irradiation amount of 60 mJ / cm ² are irradiated. Then, the coating layer was cured to form a low moisture permeable layer. The coating amount was adjusted so that the film thickness of the low moisture permeable layer was 30 μm.
In Table 1 below, the low moisture-permeable layer is simply expressed as “A-DCP”.

<Formation of hydrophilic polymer layer>
After coating the previously prepared polyvinyl alcohol aqueous solution on the surface opposite to the surface provided with the low moisture permeable layer of the acrylic resin film (base material layer), it is dried at 120 ° C. for 10 minutes, A laminate having a polyvinyl alcohol coating film having a thickness of 7 μm formed as a hydrophilic polymer layer was obtained.

[Stretching treatment]
The above laminate was stretched up to 5 times in the width direction by free end uniaxial stretching using a tenter apparatus under heating at 143 ° C. to obtain a stretched laminate. At this time, the distance between chucks was 100 mm, and the stretching speed was 2 mm / sec.
The thickness of the low moisture-permeable layer in the laminate (stretched laminate) after the stretching treatment was 15 μm, the thickness of the base material layer was 40 μm, and the thickness of the hydrophilic polymer layer was 5 μm.

[Dyeing: Formation of polarizer]
The stretched laminate after the stretching treatment was immersed in an iodine solution (mass ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension.
Thereafter, drying was performed at 60 ° C. for 4 minutes to obtain a polarizing plate.
The thickness of the low moisture-permeable layer in the obtained polarizing plate (stretched laminate) is 15 μm, the thickness of the base material layer (transparent protective film) is 40 μm, and the thickness of the hydrophilic polymer layer (polarizer) is 5 μm. Met.

[Example 2]
The low moisture-permeable layer having a coating film thickness of 12 μm and a stretched thickness of 5 μm using the following composition B-2 for forming a low moisture-permeable layer instead of the composition B-1 for forming low moisture-permeable material A polarizing plate was produced in the same manner as in Example 1 except that was formed. In Table 1 below, the low moisture-permeable layer is simply expressed as “TOPAS”.

[Preparation of composition for forming a low moisture-permeable layer]
A low moisture-permeable layer forming composition B-2 was prepared as shown below.
<Composition of Composition B-2 for Forming Low Moisture Permeability Layer>
・ Cyclic polyolefin resin TOPAS 6013
(Manufactured by Polyplastics Co., Ltd.) 100 parts by mass-cyclohexane 510 parts by mass-cyclohexanone 57 parts by mass

[Example 3]
Polarization is performed in the same manner as in Example 1, except that the low moisture-permeable layer forming composition B-3 shown below is used instead of the low moisture-permeable forming composition B-1. A plate was made. In Table 1 below, the low moisture-permeable layer is simply expressed as “silica”.

(Preparation of reactive silica particles)
<Preparation of reactive silica fine particles A>
Nissan Chemical Industries, Ltd., IPA-ST-ZL, average particle size 80 nm, colloidal silica, solid content 30% by mass IPA (isopropyl alcohol) liquid is replaced by solvent from IPA to MEK (methyl ethyl ketone) using a rotary evaporator. And a MEK dispersion with 30% by mass of silica particles was obtained. By adding 5 parts by mass of 3-methacryloxypropylmethyldimethoxysilane to 100 parts by mass of this MEK dispersion and subjecting it to a heat treatment at 50 ° C. for 1 hour, the solid content of the surface-treated reactive silica fine particles having an average particle diameter of 80 nm is obtained. A 30 mass% MEK dispersion was obtained. (The particle size was measured using the BET method.) Using a rotary evaporator, the obtained 30% by mass solution was concentrated to obtain a 40% by mass solid content MEK dispersion.

[Preparation of composition for forming a low moisture-permeable layer]
A low moisture-permeable layer forming composition B-3 was prepared as shown below. The solid content concentration of the low moisture-permeable layer forming composition B-3 was 55% by mass.
<Composition of Composition B-3 for Forming Low Moisture Permeability Layer>
・ A-DCP 46.96g
Reactive silica fine particles A (solid content 40% by mass) 120.00 g
・ Irgacure 907 3.00g
・ SP-13 represented by the above formula 0.04 g
・ MEK (methyl ethyl ketone) 6.82 g

[Example 4]
In Example 1, a polarizing plate was produced in the same manner as in Example 1 except that a polyethylene terephthalate film having a thickness of 80 μm was used as the base material layer before the stretching treatment. In Table 1 below, the base material layer is simply expressed as “PET”.

[Example 5]
Instead of the low moisture-permeable forming composition B-1, the same low moisture-permeable layer as in Example 2 (thickness after application :) using the same low moisture-permeable layer forming composition B-2 as in Example 2. A polarizing plate was produced in the same manner as in Example 4 except that 12 μm and thickness after stretching: 5 μm) were formed.

[Example 6]
The low moisture-permeable layer (thickness after application: the same as in Example 3) using the low moisture-permeable layer-forming composition B-3 as in Example 3 instead of the low moisture-permeable composition B-1 A polarizing plate was produced in the same manner as in Example 4 except that 30 μm and thickness after stretching: 15 μm) were formed.

[Example 7]
Before forming the hydrophilic polymer layer, the surface of the acrylic resin film (base material layer) opposite to the surface provided with the low moisture-permeable layer is subjected to the corona discharge treatment shown below to facilitate adhesion. A polarizing plate was produced in the same manner as in Example 1 except that a layer was formed and then a hydrophilic polymer layer was formed.
The thickness of the base material layer (transparent protective film) in the obtained polarizing plate (stretched laminate) is 40 μm, the thickness of the low moisture-permeable layer is 15 μm, the thickness of the easy-adhesion layer is 0.2 μm, and is hydrophilic. The thickness of the conductive polymer layer (polarizer) was 5 μm.

<Corona discharge treatment>
Corona discharge treatment (corona discharge electron irradiation amount: 77 W / m ² / min) was performed on the surface of the acrylic resin film (base material layer) opposite to the surface on which the low moisture permeability layer was provided.

<Formation of easy adhesion layer>
Polyester urethane (Daiichi Kogyo Seiyaku, trade name: Superflex 210, solid content: 33%) 16.8 g, cross-linking agent (oxazoline-containing polymer, product of Nippon Shokubai, trade name: Epocross WS-700, solid content: 25% ) 4.2 g, 2.0 g of 1% by mass ammonia water, 0.42 g of colloidal silica (manufactured by Fuso Chemical Industries, Quattron PL-3, solid content: 20% by mass) and 76.6 g of pure water were mixed to facilitate adhesion. An agent composition was obtained.
The obtained easy-adhesive composition was applied to a surface subjected to corona discharge treatment with a bar coater (# 6) so that the thickness after drying was 350 nm. Thereafter, the (meth) acrylic resin film was put into a hot air dryer (140 ° C.), and the easy-adhesive composition was dried for about 5 minutes to form an easy-adhesive layer (0.5 μm).

[Example 8]
Before forming the hydrophilic polymer layer, the surface of the acrylic resin film (base material layer) opposite to the surface provided with the low moisture permeability layer is subjected to the same corona discharge treatment as in Example 7. A polarizing plate was produced in the same manner as in Example 4 except that an easy-adhesion layer was formed and then a hydrophilic polymer layer was formed.

[Example 9]
Example 7 except that a low moisture permeable layer (second low moisture permeable layer) was provided using the same low moisture permeable layer forming composition B-1 as in Example 1 instead of the easy adhesion layer. A polarizing plate was produced by the same method.
The thickness of the low moisture permeable layer in the obtained polarizing plate (stretched laminate) is 15 μm, the thickness of the base material layer (transparent protective film) is 40 μm, and the thickness of the second low moisture permeable layer is 15 μm. The thickness of the hydrophilic polymer layer (polarizer) was 5 μm.

[Example 10]
Example 8 except that a low moisture permeable layer (second low moisture permeable layer) was provided using the same low moisture permeable layer forming composition B-1 as in Example 1 instead of the easy adhesion layer. A polarizing plate was produced by the same method.
The thickness of the low moisture permeable layer in the obtained polarizing plate (stretched laminate) is 15 μm, the thickness of the base material layer (transparent protective film) is 40 μm, and the thickness of the second low moisture permeable layer is 15 μm. The thickness of the hydrophilic polymer layer (polarizer) was 5 μm.

[Example 11]
A polarizing plate is produced in the same manner as in Example 4 except that the coating amount is adjusted so that the thickness of the low moisture-permeable layer before stretching is 20 μm and the thickness of the low moisture-permeable layer after stretching is 10 μm. did.

[Comparative Example 1]
A polarizing plate was produced in the same manner as in Example 1 except that the low moisture-permeable layer was not provided.

[Evaluation]
The optical properties of the obtained polarizing plate were measured with a spectrophotometer with an integrating sphere (V7100 manufactured by JASCO Corporation).
The transmittance for each linearly polarized light was measured with 100% of the completely polarized light obtained through the Grantera-prism polarizer. The single transmittance (Ts) was measured at a wavelength of 550 nm.
A single transmittance (Ts) of 42.0% or more is evaluated as “A”, and a single transmittance (Ts) of 41.5% or more and less than 42.0% is evaluated as “B”. A single transmittance (Ts) of 41.0% or more and less than 41.5% is evaluated as “C”, and a single transmittance (Ts) of less than 41.0% is evaluated as “D”. did.

From the results shown in Table 1, it was found that when a polarizing plate was produced without providing a low moisture permeable layer in the laminate, the transmittance was low and the optical properties were inferior (Comparative Example 1).
On the other hand, when a low moisture-permeable layer was provided in a laminated body and the polarizing plate was produced, it became clear that the transmittance | permeability became 41.0% or more and was excellent in the optical characteristic (Examples 1-11). Further, from the comparison of Example 4 and Example 11, when the moisture permeability of the low moisture-permeable layer is less than 100g / m ² / 24h, the transmittance is 41.5% or more, that the optical characteristics more excellent I understood. In particular, it was found that when a polarizing plate was prepared using a laminate provided with a low moisture-permeable layer on both sides of the base material layer, the transmittance was 42.0% or more, and the optical properties were further improved (Examples) 9 and 10).

DESCRIPTION OF SYMBOLS 10 Laminated body 12 Low moisture-permeable layer 14 Base material layer 16 Hydrophilic polymer layer 20 Polarizing plate 22 Low moisture-permeable layer 24 Base material layer (transparent protective film)
26 Hydrophilic polymer layer (polarizer) with adsorbed dichroic material
30 Laminate 32 First Low Moisture Permeability Layer 34 Base Material Layer 36 Hydrophilic Polymer Layer 38 Second Low Moisture Permeability Layer 40 Polarizing Plate 42 First Low Moisture Permeability Layer 44 Base Material Layer (Transparent Protective Film)
46 Hydrophilic polymer layer adsorbed with dichroic substances (polarizer)
48 2nd low moisture-permeable layer

Claims (4)

A method for producing a polarizing plate for producing a polarizing plate having a polarizer,
By applying a dyeing process to the laminate in which the low moisture-permeable layer, the base material layer, and the hydrophilic polymer layer are laminated in this order, and adsorbing the dichroic substance to the hydrophilic polymer layer, the hydrophilic A polarizer forming step for causing the functional polymer layer to function as the polarizer,
Moisture permeability of the low moisture-permeable layer is not more than 100g / m ² / 24h,
The low moisture-permeable layer has a thickness of 1 to 20 μm,
The thickness of the substrate layer, Ri 5~500μm der,
The low moisture-permeable layer is a layer formed from a composition containing a compound having a cyclic aliphatic hydrocarbon group and an unsaturated double bond in the molecule, or a cyclic polyolefin resin-containing layer,
The material of the base layer, a polyester resin, and at least 1 Tsudea Ru method of manufacturing a polarizing plate is selected from the group consisting of (meth) acrylic resin.   The method for producing a polarizing plate according to claim 1, wherein the polarizer forming step is a step of further performing a stretching treatment before the dyeing treatment, simultaneously with the dyeing treatment, or after the dyeing treatment.   The manufacturing method of the polarizing plate of Claim 1 which is the process of performing the said dyeing | staining process after the said polarizer formation process performs an extending | stretching process with respect to the said laminated body.   The manufacturing method of the polarizing plate of any one of Claims 1-3 whose thickness of the said polarizer is 0.5-30 micrometers.