JP2016014770A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device that has excellent durability of a polarizer even when the thickness is reduced.SOLUTION: There is provided an image display device that has a polarizing plate and a display element in this order from a visible side, where the polarizing plate has a polarizer and a hard coat layer arranged adjacent to the polarizer; the hard coat layer is a layer obtained by curing a curable composition containing a polymerizable monomer and a photopolymerization initiator; the photopolymerization initiator includes a photopolymerization initiator X having a base dissociation constant pKb of 8 or more; the content of the photopolymerization initiator X is 60 mass% or more relative to the total mass of the photopolymerizable initiator; the moisture permeability of a layer closer to the visible side than the polarizer is 60 g/m/24h or more.

Description

  The present invention relates to an image display device.

In recent years, thinning of liquid crystal display devices, particularly liquid crystal display devices for small and medium-sized applications, has been promoted, and accordingly, the members (for example, polarizing plates) used are required to be thinned.
Examples of the method of thinning the polarizing plate include a method of thinning the polarizer itself and the protective film of the polarizer, and a method of eliminating the protective film disposed between the polarizer and the liquid crystal cell.

  As such a thinning technique, for example, Patent Document 1 discloses that “a) a polarizer and b) at least one surface of the polarizer are (A) with respect to 100 parts by weight of the photocurable composition (A). From a photocurable composition comprising 4) to 95 parts by weight of a photocurable acrylic polymer, 4 to 95 parts by weight of (B) a polyfunctional acrylic monomer, and 1 to 20 parts by weight of (C) a photopolymerization initiator. An image display device using a “polarizing plate including a cured resin layer to be formed” is described ([claim 1] [claim 20]).

Special table 2013-513832 gazette

  The inventors of the present invention have studied the polarizing plate and the image display device described in Patent Document 1, and have found that the durability of the polarizer may be inferior depending on the type and thickness of the cured resin layer.

  Therefore, an object of the present invention is to provide an image display device that is excellent in the durability of a polarizer even when it is thinned.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have determined that a specific amount of a photopolymerization initiator exhibiting a specific base dissociation constant (pKb) for forming a hard coat layer disposed adjacent to a polarizer. By using the curable composition to be contained, it was found that an image display device with good polarizer durability can be thinned, and the present invention was completed.
That is, it has been found that the above-described problem can be achieved by the following configuration.

[1] An image display device having a polarizing plate and a display element in this order from the viewing side,
The polarizing plate has a polarizer and a hard coat layer disposed adjacent to the polarizer,
The hard coat layer is a layer obtained by curing a curable composition containing a polymerizable monomer and a photopolymerization initiator,
The photo heavy initiator includes a photo polymerization initiator X having a base dissociation constant pKb of 8 or more,
The content of the photopolymerization initiator X is 60% by mass or more based on the total mass of the photopolymerization initiator,
The image display apparatus whose water vapor transmission rate of the layer in a visual recognition side is more than 60 g / m < ² > / 24h from a polarizer.
[2] The image display device according to [1], wherein the polarizing plate includes an outer layer, a polarizer, and a hard coat layer in this order from the viewing side.
[3] The image display device according to [1] or [2], wherein the polarizer has a thickness of 2 μm to 20 μm.
[4] The image display device according to any one of [1] to [3], wherein the display element is a liquid crystal panel or an organic EL display panel.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where it thins, the image display apparatus excellent in durability of a polarizer can be provided.

1A to 1C are schematic cross-sectional views each showing an example of an embodiment of an image display device 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 image display device of the present invention is an image display device having a polarizing plate and a display element in this order from the viewing side, wherein the polarizing plate includes a polarizer and a hard coat layer disposed adjacent to the polarizer. It is an image display apparatus which has.
The hard coat layer disposed adjacent to the polarizer is a layer obtained by curing a curable composition containing a polymerizable monomer and a photopolymerization initiator. (Hereinafter also abbreviated as “pKb”) includes 8 or more photopolymerization initiators X, and the content of the photopolymerization initiators X is 60% by mass or more based on the total mass of the photopolymerization initiators. .
The image display device of the present invention, moisture permeability of the layer on the viewing side than the polarizer is 60g / m ² / 24h or more.

Here, the “hard coat layer disposed adjacent to the polarizer” refers to a hard coat layer disposed in direct contact with the polarizer layer, and in the present invention, the curability described later on the surface of the polarizer. A hard coat layer formed by direct contact (for example, coating) of the composition.
In addition, “moisture permeability of a layer on the viewer side of the polarizer” refers to the moisture permeability of the layer disposed on the viewer side of the polarizer, and a plurality of layers (for example, a protective film and a hard coat layer) are disposed on the viewer side. In this case, it refers to the total moisture permeability when the layers are laminated. Incidentally, the provisions of the "moisture permeability in viewing from the polarizer side layer is 60g / m ² / 24h or more" is intended to define that the moisture may penetrate into the polarizer is increased, in other words This is a rule indicating the conditions under which the problem of durability of the polarizer is likely to be manifested.

In the present invention, by having the above-described configuration, the durability of the polarizer is good even when the polarizing plate is thinned.
Although the reason why the durability of the polarizer is good in this way is not clear in detail, it is estimated as follows.
That is, as shown in a comparative example described later, a hard coat layer formed using a curable composition containing a photopolymerization initiator having a pKb of 8 or more and a content of photopolymerization initiator X of less than 60% by mass. It can be seen that the polarizing plate having a lower durability of the polarizer.
On the other hand, as shown in the Example mentioned later, it has the hard-coat layer formed using the curable composition containing the photoinitiator which contains 60 mass% or more of photoinitiators X whose pKb is 8 or more. It can be seen that the polarizing plate has good durability of the polarizer.
From these results, the reason why the durability of the polarizer is inferior is that a photopolymerization initiator that exists at the time of formation of the hard coat layer or remains after formation by using a photopolymerization initiator that is strongly basic, that is, has a small pKb. However, it is thought that it penetrates into the polarizer, and the boric acid bridge of the polarizer is dissociated to deteriorate the durability of the polarizer.

In the present invention, the photopolymerization initiator remaining in the hard coat layer moves to the adjacent polarizer layer and affects the durability of the polarizer, that is, the durability improvement effect of the polarizer according to the present invention is more. reasons becomes significant, it is preferable moisture permeability of the layer in the visible than the polarizer side is 100g / m ² / 24h or more, is preferably 100~1000g / m ² / 24h.
Here, the moisture permeability is 24 hours under the conditions of 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. It refers to the amount of water vapor passing through ^{(g / m 2 / 24h)} .

FIG. 1 is a cross-sectional view schematically showing an example of an embodiment of the image display apparatus of the present invention.
An image display device 10 illustrated in FIG. 1A includes a hard coat layer 1, a polarizer 2, and a display element 3.
An image display device 10 illustrated in FIG. 1B includes an outer protective film 4, a polarizer 2, a hard coat layer 1, and a display element 3.
An image display device 10 illustrated in FIG. 1C includes an outer layer 6 including an outer hard coat layer 5 and an outer protective film 4, a polarizer 2, a hard coat layer 1, and a display element 3. In the embodiment shown in FIG. 1 (C), the outer hard coat layer 5 and the outer protective film 4 are provided as the outer layer 6, but only the outer hard coat layer 5 is provided, that is, FIG. The aspect which changed the outer side protective film 4 in the outer side hard-coat layer 5 in ()) may be sufficient.
Below, each layer which comprises the image display apparatus of this invention is explained in full detail.

[Polarizer]
The polarizing plate which the image display apparatus of this invention has has a polarizer and the hard-coat layer arrange | positioned adjacent to a polarizer.

[Polarizer]
The polarizer included in the polarizing plate is not particularly limited, and a commonly used polarizer can be used.
Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples include those obtained by adsorbing substances and uniaxially stretched; polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride.
Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable.

<Thickness>
Although the thickness of a polarizer is not specifically limited, From a viewpoint of thickness reduction of a polarizing plate, it is preferable that it is 2 micrometers-20 micrometers, and it is more preferable that it is 5 micrometers-15 micrometers.

[Hard coat layer]
The hard coat layer of the polarizing plate is a layer that is disposed adjacent to the above-described polarizer and is obtained by curing a curable composition containing a polymerizable monomer and a photopolymerization initiator.
In the following description, as shown in FIG. 1A, a hard coat layer disposed adjacent to the viewing side of the polarizer is referred to as an “outer hard coat layer”, as shown in FIG. In addition, a hard coat layer disposed adjacent to the display element side of the polarizer is referred to as an “inner hard coat layer”. However, when it is not particularly necessary to distinguish, it is simply referred to as a “hard coat layer”.
Further, as shown in FIG. 1C, in addition to the hard coat layer disposed adjacent to the polarizer, it may further include a hard coat layer not adjacent to the polarizer. However, a hard coat layer may be disposed adjacent to either the viewing side or the display element side of the polarizer.

<Thickness>
The thickness of the hard coat layer is preferably 10 μm or less because the thickness of the polarizing plate is reduced, the pencil hardness of the polarizing plate surface is made better, and the brittleness of the polarizing plate is made better. More preferably, it is 1 μm to 5 μm.

<Moisture permeability>
The moisture permeability of the outer hard coat layer, although the moisture permeability of the layers in the visible than the polarizer side is not particularly limited as long as the moisture permeability to be 60g / m ² / 24h or more and 200g / m ² / 24h or more It is more preferable that it is 300-5000 g / m < ² > / 24h.

<Curable composition>
The curable composition for forming the hard coat layer is not particularly limited as long as it is a composition containing a specific amount of a photopolymerization initiator X described later. For example, a compound having a photopolymerization initiator and an unsaturated double bond And a composition containing a solvent which may be blended as desired.

(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 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.

  “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 photopolymerization initiators include “Irgacure 127 (pKb: 13)”, “Irgacure 184 (pKb: 17)”, “Irgacure 819 (pKb: 24)”, “Irgacure 907” manufactured by BASF. (PKb: 5.6) ”,“ Irgacure 369 (pKb: 5.3) ”,“ Irgacure 1173 (pKb: 16) ”,“ Irgacure 2959 (pKb: 14) ”, etc .; manufactured by Nippon Kayaku Co., Ltd. “Kaya Cure DETX-S”, “Kaya Cure BP-100”, “Kaya Cure BDMK”, “Kaya Cure CTX”, “Kaya Cure BMS”, “Kaya Cure 2-EAQ”, “Kaya Cure ABQ”, “Kaya Cure CPTX”, “Kaya Cure EPD” , “Kayacure ITX”, “Kayacure QTX”, “Kayacure BTC” "KAYACURE MCA" and the like; Sartomer Co. "Esacure (KIP100F, KB1, EB3, BP, X33, KTO46, KT37, KIP150, TZT)" or the like, and combinations thereof Preferred examples.

In the present invention, among the photopolymerization initiators exemplified above, a photopolymerization initiator (photopolymerization initiator X) having a base dissociation constant (pKb) of 8 or more is used.
Here, pKb refers to pKb at a water temperature of 25 ° C., and is one of the indexes for quantitatively representing the strength of the base, and is synonymous with the basicity constant. E. Martell, R.A. M.M. Smith, “Critical Stability Constants”, Vol. 1-3, Plenum Press (1974, 1975, 9177), and the acid dissociation constant (pKa) can be obtained from the formula pKb = 14.0-pKa.

  The content of the photopolymerization initiator X in the curable composition is 60% by mass or more, preferably 65% by mass or more, and more than 80% by mass with respect to the total mass of the photopolymerization initiator. More preferably, it is 100% by mass, that is, it is still more preferable that only the photopolymerization initiator X is used as the photopolymerization initiator.

(Compound having an unsaturated double bond)
Examples of the compound having an unsaturated double bond include compounds having an ethylenic functional group such as a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group, and among them, a compound having a (meth) acryloyl group is preferable. .
In addition, “(meth) acryloyl group” is an expression representing “methacryloyl group or acryloyl group”. Similarly, “(meth) acrylate” described later represents “methacrylate or acrylate” and “(meth) acrylate described later”. “Acrylic acid” means “methacrylic acid or acrylic acid”.

  Specific examples of the compound having an ethylenically unsaturated bond include (meth) acrylic acid diesters of alkylene glycol, (meth) acrylic acid diesters of polyoxyalkylene glycol, (meth) acrylic acid diesters of polyhydric alcohol, Examples include (meth) acrylic acid diesters of adducts of ethylene oxide or propylene oxide, epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, and the like.

  Among these, esters of polyhydric alcohol and (meth) acrylic acid are preferable. For example, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate , Pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, EO modified trimethylolpropane tri (meth) acrylate, PO modified trimethylolpropane tri (meth) acrylate, EO modified Tri (meth) acrylate phosphate, trimethylolethane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate Rate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate, caprolactone-modified tris (acryloxyethyl) isocyanurate, etc. Can be mentioned.

  Commercially available polyfunctional acrylate compounds having a (meth) acryloyl group can be used, such as NK ester A-TMMT manufactured by Shin-Nakamura Chemical Co., Ltd., KAYARAD manufactured by Nippon Kayaku Co., Ltd. DPHA etc. can be mentioned. The polyfunctional monomer is described in paragraphs [0114] to [0122] of JP-A-2009-98658, and the same applies to the present invention.

(solvent)
The arbitrary solvent is not particularly limited, but an alcohol solvent and a ketone solvent are preferably used.
Specifically, acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexane, 2-heptanone, 4-heptanone, methyl isopropyl ketone, ethyl isopropyl ketone, diisopropyl ketone, methyl isobutyl ketone, methyl-t-butyl ketone, Examples thereof include diacetyl, acetylacetone, acetonylacetone, diacetone alcohol, mesityl oxide, chloroacetone, cyclopentanone, cyclohexanone, acetophenone, and the like. Among these, methyl ethyl ketone and methyl isobutyl ketone are preferable. These solvents may be used alone or in a mixture at an arbitrary mixing ratio.

[Outer layer]
In the present invention, when the hard coat layer described above is disposed on the display element side of the polarizer, that is, when the hard coat layer adjacent to the polarizer is disposed as the inner hard coat layer, the image display device of the present invention is The polarizing plate has an outer layer disposed on the viewing side of the polarizer.
Here, examples of the outer layer include an outer protective film and an outer hard coat layer. Among them, an embodiment in which only the outer protective film is disposed on the viewing side of the polarizer (FIG. 1 (B)) or a polarizer. It is preferable that the outer hard coat layer and the outer protective film are disposed from the viewing side (FIG. 1C).

<Outer protective film>
Specifically, as the outer protective film, for example, cellulose acylate film, (meth) acrylic resin film, cycloolefin resin film, polyester resin film, polycarbonate resin film, polyolefin resin film, etc. A plastic resin film is mentioned.
The (meth) acrylic resin is a concept including both a methacrylic resin and an acrylic resin, and includes an acrylate / methacrylate derivative, particularly an acrylate ester / methacrylate ester (co) polymer. In addition to methacrylic resins and acrylic resins, (meth) acrylic resins also include (meth) acrylic polymers having a ring structure in the main chain, polymers having a lactone ring, and succinic anhydride rings. A maleic anhydride-based polymer, a polymer having a glutaric anhydride ring, and a glutarimide ring-containing polymer.
Among these, a cellulose acylate film and a (meth) acrylic resin film are preferable from the viewpoint of processability and optical performance.

As the cellulose acylate film that can be suitably used as the outer protective film, various known films can be used, and specifically, for example, those described in JP 2012-076051 A can be used. Can do.
As the (meth) acrylic resin-based film, various known ones can be used. Specifically, for example, acrylics described in paragraphs [0032] to [0063] of JP 2010-079175 are disclosed. A film, a lactone ring-containing polymer described in paragraphs [0017] to [0107] of JP-A-2009-98605, and the like can be appropriately employed.

(Thickness)
The thickness of the outer protective film is preferably 5 μm to 40 μm, more preferably 10 μm to 30 μm, from the viewpoint of thinning the polarizing plate.

(Moisture permeability)
The moisture permeability of the outer protective film, the although moisture permeability of the layers in the visible than the polarizer side is not particularly limited as long as the moisture permeability to be 60g / m ² / 24h or more and 105g / m ² / 24h or higher preferably, it is preferred that 110~1000g / m ² / 24h.

<Outside hard coat layer>
Examples of the outer hard coat layer include those similar to the hard coat layer described above, but as shown in FIG. 1C, the outer hard coat layer is disposed on the outer protective film without being adjacent to the viewing side of the polarizer. Regarding the hard coat layer, the value of the base dissociation constant (pKb) and the like are not particularly limited, and those described in paragraphs [0190] to [0196] of JP-A-2009-98658 can be used.

[Adhesive layer / adhesive layer]
The polarizing plate included in the image display device of the present invention may have a pressure-sensitive adhesive layer or an adhesive layer in consideration of bonding with a liquid crystal cell or an organic EL display panel described later.
The pressure-sensitive adhesives and adhesives that can be used in the present invention are not particularly limited, and commonly used pressure-sensitive adhesives (for example, acrylic pressure-sensitive adhesives) and adhesives (for example, polyvinyl alcohol-based adhesives) can be used. .
Examples of pressure-sensitive adhesives and adhesives that can be used in the present invention include paragraphs [0100] to [0115] of JP2011-037140A, and paragraphs [0155] to [0155] of JP2009-292870A. [0171] and the like can be used.

[Display element]
The display element which the image display apparatus of this invention has is not specifically limited, For example, a liquid crystal panel, an organic EL display panel, a plasma display panel etc. are mentioned.
Among these, a liquid crystal panel and an organic EL display panel are preferable. That is, the image display device of the present invention is preferably a liquid crystal display device using a liquid crystal panel as a display element and an organic EL display device using an organic EL display panel as a display element.

[Liquid Crystal Display]
As a liquid crystal display device which is an example of the image display device of the present invention, for example, a liquid crystal display device having a liquid crystal cell and a pair of polarizing plates arranged with the liquid crystal panel sandwiched therebetween, A preferred embodiment is one in which at least one of the polarizing plates is composed of the above-described polarizing plates.
In the present invention, among the polarizing plates provided on both sides of the liquid crystal panel, it is preferable to use the polarizing plate described above as the polarizing plate on the viewing side, and the polarizing plate described above as the polarizing plate on the viewing side and the backlight side. More preferably it is used.

[Liquid crystal cell]
The liquid crystal cell used in the image display device (liquid crystal display device) of the present invention is preferably VA mode, OCB mode, IPS mode, or TN mode, but is not limited thereto.
In a TN mode liquid crystal cell, rod-like liquid crystal molecules are substantially horizontally aligned when no voltage is applied, and are twisted and aligned at 60 to 120 °. The TN mode liquid crystal cell is most frequently used as a color TFT liquid crystal display device, and is described in many documents.
In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied. The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of tech. Papers (Preliminary Proceed) 28 (1997) 845 in which the VA mode is converted into a multi-domain (MVA mode) for widening the viewing angle. ), (3) A liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary collections 58-59 of the Japan Liquid Crystal Society) (1998)) and (4) SURVIVAL mode liquid crystal cells (announced at LCD International 98). Moreover, any of PVA (Patterned Vertical Alignment) type, optical alignment type (Optical Alignment), and PSA (Polymer-Stained Alignment) may be used. Details of these modes are described in JP-A-2006-215326 and JP-T-2008-538819.
In an IPS mode liquid crystal cell, rod-like liquid crystal molecules are aligned substantially parallel to the substrate, and the liquid crystal molecules respond in a planar manner when an electric field parallel to the substrate surface is applied. The IPS mode displays black when no electric field is applied, and the absorption axes of the pair of upper and lower polarizing plates are orthogonal. JP-A-10-54982, JP-A-11-202323, and JP-A-9-292522 are methods for reducing leakage light at the time of black display in an oblique direction and improving a viewing angle using an optical compensation sheet. No. 11-133408, No. 11-305217, No. 10-307291, and the like.

[Organic EL display device]
As an organic EL display device which is an example of the image display device of the present invention, for example, from the viewing side, the polarizing plate of the present invention and a plate having a λ / 4 function (hereinafter also referred to as “λ / 4 plate”). The aspect which has an organic electroluminescent display panel in this order is mentioned suitably.
Here, the “plate having a λ / 4 function” refers to a plate having a function of converting linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). For example, a λ / 4 plate Specific examples of the embodiment in which is a single layer structure include a stretched polymer film, a retardation film provided with an optically anisotropic layer having a λ / 4 function on a support, and the like. As an aspect in which the four plates have a multilayer structure, specifically, there is a broadband λ / 4 plate formed by laminating a λ / 4 plate and a λ / 2 plate.
The organic EL display panel is a display panel configured using an organic EL element in which an organic light emitting layer (organic electroluminescence layer) is sandwiched between electrodes (between a cathode and an anode).
The configuration of the organic EL display panel is not particularly limited, and a known configuration is adopted.

  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.

(1) Production of outer protective film [Production of TAC-1 and TAC-2]
<Preparation of cellulose acylate solution T1>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution T1.

―――――――――――――――――――――――――――――――――――
Composition of cellulose acylate solution T1 ――――――――――――――――――――――――――――――――――――
-Degree of acetyl substitution 2.87, weight average molecular weight 200,000
Cellulose acetate 100.0 parts by mass-Compound (A1) 5.8 parts by mass-Compound (A2) 1.8 parts by mass-Compound (U1) 4.0 parts by mass-Methylene chloride (first solvent) 402.0 parts by mass Methanol (second solvent) 60.0 parts by mass ―――――――――――――――――――――――――――――――――――

  The following compounds were used as the compound (A1). In the following structural formula, R represents a benzoyl group, and an average substitution degree of 5 to 7 was used.

The following compounds were used as the compound (A2) (respective structural formulas and substitution degrees of R ⁹ are as follows).

The following compounds were used as the compound (U1).

<Preparation of acrylic resin solution P1>
Next, Dianal BR88 (manufactured by Mitsubishi Rayon Co., Ltd.) was dissolved in methylene chloride and methanol, and the concentration was adjusted so as to have the same viscosity as that of the cellulose acylate solution T1, thereby preparing an acrylic resin solution P1.

<Co-cast film production>
Solution casting film formation was performed using the cellulose acylate solution T1 and the acrylic resin solution P1, and a peelable laminated film was prepared so as to have the structure shown in Table 1 below.
Specifically, the film was cast on a metal support through a casting Giuser capable of two-layer co-casting so as to have the layer configuration shown in Table 1 below.
At this time, casting is performed in order from the metal support surface side so as to be a lower layer and an upper layer, and the viscosity of each layer is appropriately adjusted with the solid content concentration according to the combination of each dope so that co-casting is possible And set so that uniform casting is possible. While being on the metal support, the dope is dried with a drying air at 40 ° C. to form a peelable laminated film, and then peeled off. Both ends of the peelable laminated film are fixed with pins, and the gap is kept at the same interval. It dried for 5 minutes with the drying wind of 105 degreeC. After removing the pin, the film was further dried at 130 ° C. for 20 minutes and wound up in the state of a laminated film.
Subsequently, the thin film of the upper layer was peeled from the lower layer, and the cellulose acylate film which has the film thickness of Table 1 below was obtained, respectively.

[Production of acrylic polymer film]
To a reaction vessel having an internal volume of 30 L equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introduction pipe, 41.5 parts by mass of methyl methacrylate (MMA), 6 parts by mass of methyl 2- (hydroxymethyl) acrylate ( MHMA), 2.5 parts by mass of 2- [2′-hydroxy-5′-methacryloyloxy] ethylphenyl] -2H-benzotriazole (manufactured by Otsuka Chemical, trade name: RUVA-93), 50 parts by mass as a polymerization solvent Toluene, 0.025 parts by mass of antioxidant (Asahi Denka Kogyo Co., Ltd., Adeka Stub 2112), and 0.025 parts by mass of n-dodecyl mercaptan as a chain transfer agent, The temperature was raised to 105 ° C.
When refluxing with increasing temperature started, 0.05 parts by mass of t-amylperoxyisononanoate (manufactured by Arkema Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator, and 0.10 parts by mass of While t-amyl peroxy isononanoate was added dropwise over 3 hours, solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C., followed by further aging for 4 hours.

Next, 0.05 parts by mass of 2-ethylhexyl phosphate (manufactured by Sakai Chemical Industry, Phoslex A-8) is added to the resulting polymerization solution as a catalyst for the cyclization condensation reaction (cyclization catalyst). The cyclization condensation reaction was allowed to proceed for 2 hours under reflux at 110 ° C., and then the polymerization solution was heated for 30 minutes in an autoclave at 240 ° C. to further proceed the cyclization condensation reaction.
Next, 0.94 parts by mass of CGL777MPA (manufactured by Ciba Specialty Chemicals) as an ultraviolet absorber was mixed into the polymerization solution after the reaction proceeded.

Next, the obtained polymerization solution was subjected to a barrel temperature of 240 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1 and a forevent number of 4 (first and 2, third and fourth vents), a vent type screw twin screw extruder (Φ = 50.0 mm, with a leaf disk type polymer filter (filtration accuracy 5 μm, filtration area 1.5 m ² ) at the tip. L / D = 30) was introduced at a treatment rate of 45 kg / hr in terms of resin amount, and devolatilization was performed. At that time, a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator was charged at a rate of 0.68 kg / hour from the back of the first vent, and ion-exchanged water was charged at 0.22 kg / hour. Each was fed from behind the third vent at a speed.

  In the mixed solution of the antioxidant / cyclization catalyst deactivator, 50 parts by mass of an antioxidant (Sumitomo Chemical Sumitizer GS) and 35 parts by mass of zinc octylate (made by Nippon Kagaku Sangyo Co., Ltd., Nikka) A solution in which octix zinc (3.6%) was dissolved in 200 parts by mass of toluene was used.

  Next, after completion of devolatilization, the resin in the hot melt state remaining in the extruder is discharged while being filtered through a polymer filter from the tip of the extruder, pelletized by a pelletizer, and has a lactone ring structure in the main chain A pellet of a transparent resin composition containing an acrylic resin and an ultraviolet absorber was obtained. The weight average molecular weight of the resin was 145000, and the glass transition temperature (Tg) of the resin and the resin composition was 122 ° C.

  A pellet of a transparent resin composition containing an acrylic resin having a lactone ring structure in the main chain and an ultraviolet absorber prepared above was melt-extruded from a coat hanger type T die using a twin screw extruder, and the thickness was 20 μm. An acrylic polymer film was prepared.

(2) Preparation of coating solution for outside hard coat layer <Preparation of coating solution for outside hard coat layer (HC-0)>
Each component was prepared with the composition shown in the table below, and filtered through a polypropylene filter having a pore size of 30 μm to prepare a coating liquid for outer hard coat layer (HC-0).
―――――――――――――――――――――――――――――――――――
Composition of the coating solution (HC-0) for the outer hard coat layer ―――――――――――――――――――――――――――――――――――
-DPHA (binder) 22.9 parts by mass-PET-30 (binder) 22.9 parts by mass-Irgacure 184 (photopolymerization initiator) 1.5 parts by mass-MEK (solvent) 45.2 parts by mass-FP-13 (Leveling agent) 0.1 parts by mass ―――――――――――――――――――――――――――――――――――

The compounds used in the composition of the outer hard coat layer coating solution (HC-0) are shown below.
DPHA: Mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (manufactured by Nippon Kayaku Co., Ltd.)
PET30: A mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (manufactured by Nippon Kayaku Co., Ltd.)
Irgacure 184: photopolymerization initiator (pKb: 17, manufactured by BASF)
FP-13: Fluorosurfactant described in JP2009-063983A [0341]

(3) Preparation of coating solution for inner hard coat layer <Preparation of coating solution for inner hard coat layer (HC-1)>
Each component was prepared with the composition shown in the table below and filtered through a polypropylene filter having a pore size of 30 μm to prepare a coating solution for the inner hard coat layer.
―――――――――――――――――――――――――――――――――――
Composition of inner hard coat layer coating solution (HC-1) ―――――――――――――――――――――――――――――――――――
-A-TMMT (binder) 45.8 parts by mass-Irgacure 127 (photopolymerization initiator) 1.5 parts by mass-MEK (solvent) 45.2 parts by mass-Boronic acid compound 0.3 parts by mass-Leveling agent 0. 1 part by mass ――――――――――――――――――――――――――――――――――――

The compounds used in the composition of the inner hard coat layer coating solution (HC-1) are shown below.
A-TMMT: pentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.)
Irgacure 127: photopolymerization initiator (pKb: 13, manufactured by BASF)

Boronic acid compound: Compound 1 represented by the following formula

Leveling agent: a copolymer having a weight average molecular weight of 160000 (compound 2) having the repeating units shown in Table 2 below in the content (mol%) shown in Table 2 below.

<Preparation of coating solutions for inner hard coat layer (HC-2) to (HC-10)>
Instead of part or all of Irgacure 127, the inner hard coat layer except that the photopolymerization initiator shown in Table 3 below was blended so that the content of the photopolymerization initiator X was mass% shown in Table 3 below. The inner hard coat layer coating solutions (HC-2) to (HC-10) were prepared in the same manner as the coating solution for coating (HC-1).
Specifically, for the inner hard coat layer coating solution (HC-2), Irgacure 907 (pKb: 5.6, BASF) is used so that Irgacure 127 (pKb: 13, manufactured by BASF) is 60% by mass. And 1.5 parts by mass in total. The same applies to the inner hard coat layer coating solutions (HC-3) to (HC-10).
For the inner hard coat layer coating solution (HC-6), Irgacure 127 (pKb: 13, manufactured by BASF) and Irgacure 184 (pKb: 17, manufactured by BASF) were added at a mass ratio of 50:50. 1.5 parts by mass was prepared.

(4) Production of Polarizer <Production of Polarizer 1 (Thickness: 30 μm)>
A polyvinyl alcohol (PVA) film having a thickness of 60 μm was immersed in pure water at 25 ° C. for 60 seconds and swelled, and then stretched 1.30 times. The obtained film is dyed by immersing it in a staining solution containing 0.2 parts by mass of iodine and 5 parts by mass of potassium iodide for 30 seconds at 25 ° C. with respect to 100 parts by mass of water. While being immersed in a crosslinking solution containing 4.3 parts by mass of boric acid and 3 parts by mass of potassium iodide at 60 ° C. for 80 seconds, the polymer was stretched 6 times relative to the original part. This stretched film was dried in an oven at 100 ° C. for 4 minutes to produce a polarizer having a thickness of 30 μm.

<Preparation of polarizer 2 (thickness: 15 μm)>
A polyvinyl alcohol (PVA) film having a thickness of 40 μm was immersed in pure water at 25 ° C. for 60 seconds, subjected to swelling treatment, and then stretched 1.30 times. The obtained film is dyed by immersing it in a staining solution containing 0.2 parts by mass of iodine and 5 parts by mass of potassium iodide for 30 seconds at 25 ° C. with respect to 100 parts by mass of water. While being immersed in a crosslinking solution containing 4.3 parts by mass of boric acid and 3 parts by mass of potassium iodide at 60 ° C. for 80 seconds with respect to parts by mass, the film was stretched 8 times the original length. This stretched film was dried in an oven at 100 ° C. for 4 minutes to produce a polarizer having a thickness of 15 μm.

<Preparation of Polarizer 3 (Thickness: 8 μm)>
A polyvinyl alcohol (PVA) film having a thickness of 20 μm was immersed in pure water at 25 ° C. for 60 seconds, subjected to swelling treatment, and then stretched 1.30 times. After dyeing the obtained film by immersing it in a staining solution containing 0.3 parts by mass of iodine and 7.5 parts by mass of potassium iodide for 30 seconds at 25 ° C. with respect to 100 parts by mass of water, The film was stretched 8 times the original length while being immersed in a crosslinking solution containing 4.3 parts by mass of boric acid and 3 parts by mass of potassium iodide for 80 seconds at 60 ° C. with respect to 100 parts by mass of water. This stretched film was dried in an oven at 100 ° C. for 4 minutes to produce a polarizer having a thickness of 8 μm.

<Preparation of polarizer 4 (thickness: 5 μm)>
A polyvinyl alcohol (PVA) film having a thickness of 20 μm was immersed in pure water at 25 ° C. for 60 seconds, subjected to swelling treatment, and then stretched 1.30 times. After dyeing the obtained film by immersing it in a staining solution containing 0.3 parts by mass of iodine and 7.5 parts by mass of potassium iodide for 30 seconds at 25 ° C. with respect to 100 parts by mass of water, The film was stretched 12 times the original length while being immersed in a crosslinking solution containing 4.3 parts by mass of boric acid and 3 parts by mass of potassium iodide for 80 seconds at 60 ° C. with respect to 100 parts by mass of water. This stretched film was dried in an oven at 100 ° C. for 4 minutes to produce a polarizer having a thickness of 5 μm.

[Examples 1 to 20 and Comparative Examples 1 to 10]
<Preparation of polarizing plate>
(Formation of outer hard coat layer)
The outer protective film produced above was used as a support, and an outer hard coat layer coating solution (HC-0) was applied on the support by a die coating method. After drying at room temperature for 120 seconds and further at 60 ° C. for 150 seconds, using a 160 W / cm air-cooled metal halide lamp (produced by Eye Graphics Co., Ltd.) while purging with nitrogen (oxygen concentration 0.5% or less), the illuminance The coating layer was cured by irradiating ultraviolet rays at 400 mW / cm ² and an irradiation amount of 150 mJ / cm ² to form an outer hard coat layer. The thickness of the outer hard coat layer after drying was 3 μm.

(Saponification treatment)
Then, about the aspect which used TAC-1 and TAC-2 as an outer side protective film, the surface of the side which has not provided the outer side hard-coat layer of the produced outer side protective film in 2.3 mol / L sodium hydroxide aqueous solution, It was immersed for 3 minutes at 55 ° C.
Subsequently, it wash | cleaned in the water-washing bath at room temperature, and neutralized using 0.05 mol / L sulfuric acid at 30 degreeC.
Then, it wash | cleaned again in the water-washing bathtub of room temperature, and also dried with 100 degreeC warm air.
In this way, the surface of the outer protective film was saponified.

(Preparation of polarizing plate)
Next, for an embodiment using TAC-1 and TAC-2 as the outer protective film, a polarizer shown in the following Table 4 using a polyvinyl alcohol adhesive on the surface of the outer protective film subjected to the saponification treatment described above. Affixed to one side. At this time, the transmission axis of the polarizer and the slow axis of the outer layer were arranged in parallel.
On the other hand, about the aspect which used the acrylic polymer film as an outer side protective film, on the surface of the side which does not have the outer side hard-coat layer of an outer side protective film, it uses the following epoxy adhesive composition, and is shown in following Table 4 Affixed to one side of the polarizer shown. At this time, the transmission axis of the polarizer and the slow axis of the outer layer were arranged in parallel.
<Epoxy adhesive composition>
3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate 40 parts by mass Bisphenol A type epoxy resin 60 parts by mass Diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate (cationic polymerization initiator) 4 1.0 part by mass ・ Benzoin methyl ether (photosensitizer) 1.0 part by mass

(Formation of inner hard coat layer)
Next, an inner hard coat layer of the type shown in Table 4 below is formed on the surface opposite to the outer layer of the polarizer by a die coating method using a slot die described in Example 1 of JP-A-2006-122889. Coating solutions (HC-1) to (HC-10) for coating were applied under the condition of a conveyance speed of 24 m / min and dried at 60 ° C. for 60 seconds. Thereafter, an ultraviolet ray having an illuminance of 400 mW / cm ² and an irradiation amount of 390 mJ / cm ² using a 160 W / cm air-cooled metal halide lamp (produced by Eye Graphics Co., Ltd.) under a nitrogen purge (oxygen concentration of about 0.1%). Was applied to cure the coating layer and wound up. The coating amount was adjusted so that the thickness of the cured layer was 2 μm. In this way, a polarizing plate was produced.

[Evaluation of durability]
For the polarizers of Examples and Comparative Examples were prepared as described above, I ₃ ^- in the absorbent skirt corresponding to a wavelength 410nm, and I ₃ ^- a cross transmittance of the polarizer corresponding to the hem of the absorption · I ₂ at a wavelength 680nm below Measurements were made as described. Then, after storing for 1000 hours in an environment of 60 ° C. and 90% relative humidity, the orthogonal transmittance was measured by the same method at a wavelength of 410 nm and a wavelength of 680 nm. The change in orthogonal transmittance before and after aging was determined, and this was applied to the following evaluation criteria as the durability of the polarizer. The results are shown in Table 4.

<Measurement of orthogonal transmittance>
Two samples (5 cm × 5 cm) in which the polarizing plates of each Example and Comparative Example were attached on glass were prepared. At this time, the polarizing plate protective layer was attached so as to be on the side opposite to the glass (air interface) side. The orthogonal transmittance measurement was performed using an automatic polarizing film measuring apparatus VAP-7070 manufactured by JASCO Corporation with the polarizing plate protective layer side of this sample set to the light source. Two samples were measured respectively, and the average value was defined as the orthogonal transmittance.

<Evaluation criteria>
A: Change in orthogonal transmittance is less than 0.01% B: Change in orthogonal transmittance is 0.01% or more and less than 0.1% C: Change in orthogonal transmittance is 0.1% or more, 1 Less than 0.0% D: Change in orthogonal transmittance is 1.0% or more

From the above results, the hard coat layer adjacent to the polarizer contains the photopolymerization initiator X having a base dissociation constant pKb of 8 or more, and the content of the photopolymerization initiator X is the total mass of the photopolymerization initiator. As for the polarizing plate of Examples 1-20 which formed the hard-coat layer using the curable composition (HC-1 to HC-6) which is 60 mass% or more with respect to all, the durability of a polarizer is favorable. I found out that
In particular, from the comparison of Examples 1 to 20, a curable composition (HC-1 and HC-4 to HC) in which the content of the photopolymerization initiator X is 100% by mass with respect to the total mass of the photopolymerization initiator. It was found that in the example in which the hard coat layer was formed using -6), the durability of the polarizer was improved.

DESCRIPTION OF SYMBOLS 1 Hard coat layer 2 Polarizer 3 Display element 4 Outer protective film 5 Outer hard coat layer 6 Outer layer 10 Image display apparatus

Claims (4)

From the viewing side, an image display device having a polarizing plate and a display element in this order,
The polarizing plate has a polarizer and a hard coat layer disposed adjacent to the polarizer,
The hard coat layer is a layer obtained by curing a curable composition containing a polymerizable monomer and a photopolymerization initiator,
The photoinitiator includes a photopolymerization initiator X having a base dissociation constant pKb of 8 or more;
The content of the photopolymerization initiator X is 60% by mass or more based on the total mass of the photopolymerization initiator,
The moisture permeability of the layers that from the polarizer on the viewing side is 60g / m ² / 24h or more, the image display device.   The image display apparatus according to claim 1, wherein the polarizing plate includes an outer layer, the polarizer, and the hard coat layer in this order from the viewing side.   The image display device according to claim 1, wherein the polarizer has a thickness of 2 μm to 20 μm.   The image display device according to claim 1, wherein the display element is a liquid crystal panel or an organic EL display panel.