JP2020046649A - Polarizing plate with front plate - Google Patents

Abstract

To provide a polarizing plate with a front plate, which has a small decrease in optical performance over time and has excellent flexibility.SOLUTION: The polarizing plate with a front plate includes: a polarization plate having a diffusion prevention layer A, a polarizer, and a diffusion prevention layer B in this order; and a front plate disposed on an opposite side to the polarizer side in the diffusion prevention layer A or the diffusion prevention layer B. The front plate is laminated on the polarization plate with an adhesive layer therebetween. The thickness of the diffusion prevention layer A and the diffusion prevention layer B is 20 μm or less, and the thickness of the polarizer is 10 μm or less. An adhesive forming the adhesive layer has a storage elastic modulus of 0.7 MPa or less at 25°C.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polarizing plate with a front plate.

  2. Description of the Related Art A polarizing plate including a polarizer is incorporated in a display device such as a liquid crystal display device and an organic EL display device. Examples of the polarizer include a polarizer in which a dichroic dye such as iodine is oriented and adsorbed on a polyvinyl alcohol-based resin film, and a polarizer produced by applying a composition containing a polymerizable liquid crystal to a substrate. Have been.

WO 2017/154907

  In response to consumer demand for thinner portable devices, there has been a demand for thinner display devices, and coating-type polarizers that do not necessarily require a protective film, which were necessary for conventional polarizers, have become thinner. This is a very useful technique because the conversion is relatively easy. However, in such a coating type polarizer, optical performance such as polarization performance may deteriorate with time in a high temperature environment. Further, the coating type polarizer is superior in that there is no restriction in the bending direction as compared with a polarizer in which a dichroic dye such as iodine is oriented and adsorbed on a polyvinyl alcohol-based resin film, but the type of front plate and the front plate are not limited. It has become clear that there is room for improvement in the flexibility depending on the type of the pressure-sensitive adhesive layer disposed between the polarizing plate and the polarizing plate.

  Then, an object of the present invention is to provide a polarizing plate with a front plate, which has little deterioration of optical performance with time in a high temperature environment and is excellent in flexibility.

The present invention provides the following preferred embodiments [1] to [11].
[1] A polarizing plate having a diffusion prevention layer A, a polarizer, and a diffusion prevention layer B in this order,
And a front plate disposed on the side opposite to the polarizer side in the diffusion prevention layer A or the diffusion prevention layer B,
The front plate is laminated to the polarizing plate via an adhesive layer,
The thickness of the diffusion prevention layer A and the diffusion prevention layer B is 20 μm or less,
The thickness of the polarizer is 10 μm or less,
The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is a polarizing plate with a front plate, which has a storage elastic modulus at 25 ° C. of 0.6 MPa or less.
[2] The front plate is a laminated film including a resin film containing a polyimide-based polymer or a polyamide-based polymer, and a functional layer provided on at least one main surface side of the resin film. The polarizing plate with a front plate as described in 1].
[3] The polarizing plate with a front plate according to [2], wherein the functional layer is a layer having at least one function selected from the group consisting of ultraviolet absorption, surface hardness, hue adjustment, and refractive index adjustment.
[4] The tensile elastic modulus of the resin film is 4.0 GPa or more,
In a bending test in which the resin film is repeatedly bent back into a U-shape until the distance between the resin films facing each other is 3 mm, the number of times the resin film is folded until the resin film breaks exceeds 100,000 times,
The polarizing plate with a front plate according to [2] or [3], which has a yellowness of 5 or less.
[5] The polarizing plate with a front plate according to any one of [1] to [4], wherein the polarizing plate includes a retardation film on a side of the polarizer opposite to the front plate.
[6] The polarizing plate with a front plate according to [5], wherein the retardation film is laminated on the diffusion preventing layer A or the diffusion preventing layer B via an adhesive layer.
[7] The polarizing plate with a front plate according to [5] or [6], wherein the retardation film includes a λ / 4 retardation plate.
[8] The polarizing plate with a front plate according to any one of claims 1 to 7, further comprising a touch sensor.
[9] An organic EL display device comprising the polarizing plate with a front plate according to any one of [1] to [8].
[10] A flexible image display device comprising the polarizing plate with a front plate according to any one of [1] to [8].

  ADVANTAGE OF THE INVENTION This invention can provide the polarizing plate with a front plate in which the deterioration of optical performance with time is small and which is excellent in flexibility.

It is sectional drawing showing an example of a structure of the polarizing plate with a front plate. It is sectional drawing showing an example of a structure of the polarizing plate with a front plate. It is sectional drawing showing an example of a structure of the polarizing plate with a front plate. It is sectional drawing showing an example of a structure of a front plate. It is sectional drawing showing an example of a structure of a front plate. It is sectional drawing showing an example of a structure of a front plate. Indicates the method of the flexibility test.

<Polarizing plate with front plate>
The polarizing plate with a front plate of the present invention includes a polarizing plate having a diffusion preventing layer A, a polarizer, and a diffusion preventing layer B in this order. The polarizing plate with a front plate of the present invention further includes a front plate disposed on a side of the diffusion preventing layer A or B opposite to the polarizer. The front plate is laminated on the polarizing plate via an adhesive layer. The thicknesses of the diffusion prevention layer A and the diffusion prevention layer B are both 20 μm or less, and the thickness of the polarizer is 10 μm or less.

  Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiment described here, and various changes can be made without departing from the spirit of the present invention.

The configuration of the polarizing plate included in the polarizing plate with a front plate of the present invention will be described with reference to FIG. In the polarizing plate with front plate (10) of the present invention, the diffusion preventing layer A (2) is laminated on one surface of the polarizer (1), and the diffusion preventing layer B (3) is formed on the other surface of the polarizer (1). ) Has a polarizing plate (20) laminated thereon.
By having such a polarizing plate, the polarizing plate with a front plate of the present invention suppresses the dichroic dye contained in the polarizer from moving out of the film, thereby preventing the optical performance of the polarizing plate from decreasing over time. Can be suppressed. Further, an alignment film (not shown) may be laminated between the polarizer (1) and the diffusion prevention layer.

  The polarizing plate with a front plate of the present invention includes a front plate. This embodiment will be described with reference to FIG. The polarizing plate with front plate (10) of the present invention includes a front plate (4) arranged on the side of the diffusion prevention layer A (2) opposite to the polarizer (1) side. As shown in FIG. 1A, the front plate (4) can be laminated on the polarizing plate (20) via an adhesive layer (7), for example. As shown in FIG. 1B, the front plate (4) can be laminated on the polarizing plate (20) via the diffusion preventing layer A (2), for example.

In one embodiment of the present invention, the polarizing plate with a front plate of the present invention may include a retardation film (5). The polarizing plate can include a retardation film on the side of the polarizer opposite to the front plate side. In this case, the retardation film (5) may be disposed on the diffusion prevention layer B on the side opposite to the polarizer side. The retardation film can be laminated on the diffusion preventing layer B via an adhesive layer or a pressure-sensitive adhesive layer, for example. The retardation film may be laminated on the polarizing plate via the diffusion preventing layer B. The present invention is not limited to the configuration described above, but also includes an embodiment in which the diffusion preventing layer A (2) in the above description is replaced with a diffusion preventing layer B (3).
Hereinafter, each component of the polarizing plate with a front plate of the present invention will be described in detail.

<Polarizer>
The polarizer of the present invention has a thickness of 10 μm or less, preferably 5 μm or less. When the thickness exceeds 10 μm, there is a possibility that a defect such as a crack may occur when bent. The polarizer may be a film-type polarizer manufactured by dyeing and stretching a polyvinyl alcohol (PVA) -based film. A dichroic dye such as iodine is adsorbed on a PVA-based film oriented by stretching or stretched in a state of being adsorbed on PVA, whereby the dichroic dye is oriented to exhibit polarizing performance. In the production of the film-type polarizer, other steps such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying may be included. The stretching and dyeing steps may be performed on the PVA-based film alone, or may be performed on a laminate with another film such as polyethylene terephthalate. The PVA-based film used is preferably 10 to 100 μm, and the stretching ratio is preferably 2 to 10 times.

  The polarizer preferably contains a polymer of a polymerizable liquid crystal and a dichroic dye, and more preferably, the dichroic dye is dispersed in a film composed of the polymer of the polymerizable liquid crystal, and is oriented. It is a film that is. Further, the polarizer may be a film composed of a dichroic dye and a polymer compound. The polarizer in the present invention is preferably a film cured in a state where the polymerizable liquid crystal is oriented in the horizontal direction with respect to the plane of the diffusion preventing layer. The horizontal alignment is an alignment having a major axis of the polymerizable liquid crystal aligned in a direction parallel to the plane of the diffusion preventing layer. Here, “parallel” means an angle of 0 ° ± 20 ° with respect to the plane of the diffusion preventing layer.

When the polarizer contains a polymerizable liquid crystal, the thickness is preferably from 0.5 μm to 3 μm, more preferably from 1 μm to 3 μm, from the viewpoint of the orientation of the polymerizable liquid crystal. When the thickness of the polarizer is greater than or equal to the above lower limit, the polymerizable liquid crystal is unlikely to be aligned in the vertical alignment direction, and the alignment order tends to be improved.
When the thickness of the polarizer film is equal to or less than the upper limit, the polymerizable liquid crystal is less likely to be randomly aligned, and the alignment order tends to be improved. The thickness of the polarizer can be measured with an interference thickness gauge, a laser microscope, or a stylus type thickness gauge.

  Generally, a polarizer is obtained by applying a composition containing a polymerizable liquid crystal and a dichroic dye (hereinafter, also referred to as a “composition for forming a polarizer”) to a substrate, a diffusion prevention layer, or an alignment film surface, and polymerizing the composition. It is obtained by polymerizing a liquid crystal. Here, it is preferable to polymerize in a state where the polymerizable liquid crystal is oriented in the horizontal direction with respect to the surface of the diffusion preventing layer. Examples of the composition for forming a polarizer and a method for producing a polarizer using the composition include those described in JP-A-2017-83843. Further, the polarizer may be manufactured from a dichroic dye and a polymer compound. As a polarizer comprising a dichroic dye and a polymer compound, those described in WO2017 / 154907 are exemplified.

[Polymerizable liquid crystal]
The polymerizable liquid crystal is a compound having a polymerizable group and exhibiting liquid crystallinity. The polymerizable group means a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in a polymerization reaction by an active radical, an acid, or the like generated from a photopolymerization initiator described below. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group and an oxetanyl group are preferred, and an acryloyloxy group is more preferred. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal.

  The polymerizable liquid crystal may be a thermotropic liquid crystal compound exhibiting a nematic liquid crystal phase or a thermotropic liquid crystal compound exhibiting a smectic liquid crystal phase. In the present invention, the polymerizable liquid crystal is preferably a thermotropic liquid crystal compound exhibiting a smectic liquid crystal phase, and more preferably a thermotropic liquid crystal compound exhibiting a higher order smectic liquid crystal phase, from the viewpoint of obtaining higher polarization characteristics. is there. Above all, a thermotropic liquid crystal compound showing a smectic B phase, a smectic D phase, a smectic E phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic I phase, a smectic J phase, a smectic K phase or a smectic L phase is more preferable. A thermotropic liquid crystal compound exhibiting a smectic B phase, a smectic F phase or a smectic I phase is more preferable. When the liquid crystal phase formed by the polymerizable liquid crystal is such a higher smectic phase, a polarizer having higher polarization performance can be manufactured. Further, such a polarizer having a high polarization performance has a Bragg peak derived from a higher-order structure such as a hexatic phase and a crystal phase in X-ray diffraction measurement. The Bragg peak is a peak derived from a periodic structure of molecular orientation, and a film having a periodic interval of 3 to 6 ° can be obtained. It is preferable that the polarizer contains a polymer of the polymerizable liquid crystal in which the polymerizable liquid crystal is polymerized in a smectic phase from the viewpoint that higher polarization characteristics can be obtained.

  Specific examples of such a compound include a compound represented by the following formula (A) (hereinafter sometimes referred to as compound (A)). The polymerizable liquid crystal may be used alone or in combination of two or more.

U ¹ -V ¹ -W ¹ -X ¹ -Y ¹ -X ² -Y ² -X ³ -W ² -V ² -U ² (A) [In the formula (A),
X ¹ , X ² and X ³ each independently represent a 1,4-phenylene group which may have a substituent or a cyclohexane-1,4-diyl group which may have a substituent. However, at least one of X ¹ , X ² and X ³ is a 1,4-phenylene group which may have a substituent. It is, -O - - -CH ₂ constituting hexane-1,4-diyl group cycloheteroalkyl, - may be replaced by S- or -NR-. R represents an alkyl group having 1 to 6 carbon atoms or a phenyl group.
Y ¹ and ^{Y 2,} independently of one _{another, -CH 2 CH 2 -, -} CH 2 O -, - COO -, - OCOO-, a single ^{bond, -N = N -, - CR} a = CR b -, - Represents C≡C- or -CR ^a = N-. R ^a and R ^b independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
U ¹ represents a hydrogen atom or a polymerizable group.
U ² represents a polymerizable group.
W ¹ and ^{W 2} are independently a single bond to one another, -O -, - S -, - representing the COO- or -OCOO-.
V ¹ and V ² independently represent an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and -CH _2- constituting the alkanediyl group is -O-,- It may be replaced by S- or -NH-. ]

In the compound (A), at least one of X ¹ , X ² and X ³ is preferably a 1,4-phenylene group which may have a substituent. Here, “may have a substituent” in the present specification has the same meaning as “unsubstituted or has a substituent”.
The 1,4-phenylene group which may have a substituent is preferably unsubstituted. The cyclohexane-1,4-diyl group which may have a substituent is preferably a trans-cyclohexane-1,4-diyl group which may have a substituent, and the substituent The trans-cyclohexane-1,4-diyl group which may have a substituent is preferably unsubstituted.

  Examples of the substituent which the 1,4-phenylene group which may have a substituent or the cyclohexane-1,4-diyl group which may have a substituent optionally have include a methyl group, an ethyl group and Examples thereof include an alkyl group having 1 to 4 carbon atoms such as a butyl group, a cyano group, and a halogen atom.

Y ¹ is preferably —CH ₂ CH ₂ —, —COO— or a single bond, and Y ² is preferably —CH ₂ CH ₂ — or —CH ₂ O—.

U ² is a polymerizable group. U ¹ is a hydrogen atom or a polymerizable group, preferably a polymerizable group. U ¹ and U ² are preferably both polymerizable groups, and more preferably both are photopolymerizable groups. Polymerizable liquid crystals having a photopolymerizable group are advantageous in that they can be polymerized under lower temperature conditions.

The polymerizable groups represented by U ¹ and U ² may be different from each other, but are preferably the same. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group and an oxetanyl group are preferred, and an acryloyloxy group is more preferred.

The alkanediyl groups represented by V ¹ and ^{V 2,} methylene group, ethylene group, propane-1,3-diyl, butane-1,3-diyl group, butane-1,4-diyl group, pentane - 1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, decane-1,10-diyl group, tetradecane-1,14-diyl And an icosan-1,20-diyl group. V ¹ and V ² are preferably an alkanediyl group having 2 to 12 carbon atoms, and more preferably an alkanediyl group having 6 to 12 carbon atoms.
Examples of the substituent optionally possessed by the alkanediyl group having 1 to 20 carbon atoms which may have a substituent include a cyano group and a halogen atom, and the alkanediyl group may be unsubstituted. More preferably, it is an unsubstituted and straight-chain alkanediyl group

W ¹ and W ² are, independently of one another, preferably a single bond or —O—.

  Specific examples of the compound (A) include compounds represented by Formulas (1-1) to (1-23). When the compound (A) has a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably in a trans form.

  The polymerizable liquid crystal is represented by Formula (1-2), Formula (1-3), Formula (1-4), Formula (-6), Formula (1-7) and Formula (1-7) among the exemplified compounds (A). 1-8), at least one selected from the group consisting of compounds represented by formulas (1-13), (1-14) and (1-15) is preferable.

  The exemplified compounds (A) can be used alone or in combination for a polarizer. When two or more polymerizable liquid crystals are combined, at least one is preferably a compound (A), and more preferably two or more is a compound (A). In some cases, by combining two or more polymerizable liquid crystals, liquid crystallinity can be temporarily maintained even at a temperature lower than the liquid crystal-crystal phase transition temperature. When two kinds of polymerizable liquid crystals are combined, the mixing ratio (liquid crystal other than compound (A): compound (A)) is usually 1:99 to 50:50, preferably 5:95 to 50:50. And more preferably 10:90 to 50:50 (mass ratio). When a polymerizable liquid crystal having one polymerizable group and a polymerizable liquid crystal having two polymerizable groups are combined, the mixing ratio thereof (polymerizable liquid crystal having one polymerizable group: polymerizable liquid crystal having two polymerizable groups) ) Is usually from 1:99 to 50:50, preferably from 5:95 to 50:50, and more preferably from 10:90 to 50:50 (mass ratio).

  Compound (A) is described, for example, in Lub et al. Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996), or a known method described in Japanese Patent No. 4719156.

  The content ratio of the polymerizable liquid crystal in the polarizer-forming composition is usually 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass with respect to 100 parts by mass of the solid content of the polarizer-forming composition. Yes, more preferably 80 to 94 parts by mass, even more preferably 80 to 90 parts by mass. When the content ratio of the polymerizable liquid crystal is within the above range, the orientation tends to be high. Here, the solid content refers to the total amount of components excluding the solvent from the polarizer-forming composition.

  The composition for forming a polarizer may contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, and a reactive additive as components other than the polymerizable liquid crystal and the dichroic dye.

[Dichroic dye]
The dichroic dye contained in the polarizer-forming composition refers to a dye having a property in which the absorbance in the major axis direction of the molecule is different from the absorbance in the minor axis direction.

  As the dichroic dye, those having an absorption maximum wavelength (λMAX) in the range of 300 to 700 nm are preferable. Such dichroic dyes include, for example, acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes and anthraquinone dyes, among which azo dyes are preferred. Examples of the azo dye include a monoazo dye, a bisazo dye, a trisazo dye, a tetrakisazo dye, and a stilbeneazo dye, and are preferably a bisazo dye and a trisazo dye. The dichroic dyes may be used alone or in combination of two or more, but it is preferable to combine three or more. In particular, it is more preferable to combine three or more azo compounds. Part of the dichroic dye may have a reactive group, and may have liquid crystallinity.

Examples of the azo dye include a compound represented by the formula (B) (hereinafter, sometimes referred to as “compound (B)”).
A ¹ (−N = N−A ² ) _p− N = N−A ³ (B)
[In the formula (B),
A ¹ and A ³ each independently represent a phenyl group which may have a substituent, a naphthyl group which may have a substituent or a monovalent heterocyclic group which may have a substituent Represents A ² represents a 1,4-phenylene group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent, or a divalent group which may have a substituent. Represents a heterocyclic group. p represents an integer of 1 to 4. If p is an integer of 2 or more, plural A ² may be the same or different from each other. ]

  Examples of the monovalent heterocyclic group include groups obtained by removing one hydrogen atom from a heterocyclic compound such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, and benzoxazole. Examples of the divalent heterocyclic group include groups in which two hydrogen atoms have been removed from the heterocyclic compound.

A phenyl group, a naphthyl group and a monovalent heterocyclic group represented by A ¹ and A ³ , and a substituent optionally possessed by a p-phenylene group, a naphthalene-1,4-diyl group and a divalent heterocyclic group represented by A ² Is an alkyl group having 1 to 4 carbon atoms; an alkoxy group having 1 to 4 carbon atoms such as methoxy group, ethoxy group and butoxy group; a fluorinated alkyl group having 1 to 4 carbon atoms such as trifluoromethyl group; a cyano group; A nitro group; a halogen atom; a substituted or unsubstituted amino group such as an amino group, a diethylamino group and a pyrrolidino group (a substituted amino group is an amino group having one or two alkyl groups having 1 to 6 carbon atoms, or two a substituted alkyl group is bonded to each other refers to an amino group which forms an alkanediyl group having 2 to 8 carbon atoms. unsubstituted amino group is -NH _2.) include Can be Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a butyl group, and a hexyl group.

  As the azo dye, among the compounds (B), compounds represented by the following formulas (2-1) to (2-6) are preferable.

[In formulas (2-1) to (2-6),
B ^{1 to} B ²⁰ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (substituted amino group and The unsubstituted amino group is as defined above), a chlorine atom or a trifluoromethyl group.
n1 to n4 independently represent an integer of 0 to 3;
If n1 is 2 or more, a plurality of B ² may be the same or different from each other,
When n2 is 2 or more, a plurality of B ⁶ may be the same or different from each other;
If n3 is 2 or more, plural B ⁹ may be the same or different from each other,
When n4 is 2 or more, a plurality of B ¹⁴ may be the same or different from each other. ]

  As the anthraquinone dye, a compound represented by the formula (2-7) is preferable.

[In the formula (2-7),
R ¹ to R ⁸ independently represent a hydrogen _{^{atom, -R x, -NH 2, -NHR}} x, -NR x 2, -SR x , or a halogen atom.
^Rx represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]

  As the oxazine dye, a compound represented by the formula (2-8) is preferable.

[In the formula (2-8),
R ⁹ to R ^15, independently of each other, represent a hydrogen _{^{atom, -R x, -NH 2, -NHR}} x, -NR x 2, the -SR ^x, or a halogen atom.
^Rx represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]

  As the acridine dye, a compound represented by the formula (2-9) is preferable.

[In the formula (2-9),
R ¹⁶ to R ²³ independently represent a hydrogen _{^{atom, -R x, -NH 2, -NHR}} x, -NR x 2, -SR x , or a halogen atom.
^Rx represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]

In the formulas (2-7), (2-8) and (2-9), the alkyl group having 1 to 4 carbon atoms represented by R ^x includes a methyl group, an ethyl group, a propyl group, and a butyl group. , A pentyl group and a hexyl group, and the aryl group having 6 to 12 carbon atoms includes a phenyl group, a toluyl group, a xylyl group, and a naphthyl group.

  As the cyanine dye, a compound represented by the formula (2-10) and a compound represented by the formula (2-11) are preferable.

ｎ５は１〜３の整数を表す。］ [In the formula (2-10),
D ¹ and D ² each independently represent a group represented by any of formulas (2-10a) to (2-10d).

n5 represents an integer of 1 to 3. ]

ｎ６は１〜３の整数を表す。］ [In the formula (2-11),
D ³ and D ⁴ each independently represent a group represented by any of formulas (2-11a) to (2-11h).

n6 represents an integer of 1 to 3. ]

  The content of the dichroic dye in the composition for forming a polarizer is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal. 0.1 to 10 parts by mass is more preferred. When the content of the dichroic dye is within the above range, polymerization can be performed without disturbing the alignment of the polymerizable liquid crystal. If the content of the dichroic dye is too large, the alignment of the polymerizable liquid crystal may be hindered. Therefore, the content of the dichroic dye can be determined within a range where the polymerizable liquid crystal can maintain the liquid crystal state.

[solvent]
The composition for forming a polarizer may contain a solvent. The solvent is preferably a solvent capable of completely dissolving the polymerizable liquid crystal, and is preferably a solvent inert to the polymerization reaction of the polymerizable liquid crystal.

  Examples of the solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone Or ester solvents such as propylene glycol methyl ether acetate and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; toluene And aromatic hydrocarbon solvents such as xylene, and nitrile solvents such as acetonitrile; Hydrofuran and ether solvents such as dimethoxyethane; chloroform and chlorine-containing solvents such as chlorobenzene; and the like. These solvents may be used alone or in combination of two or more.

  The content of the solvent is preferably 50 to 98% by mass based on the total amount of the composition for forming a polarizer. In other words, the content of the solid content in the polarizer-forming composition is preferably from 2 to 50% by mass. When the content of the solid content is 50% by mass or less, the viscosity of the composition for forming a polarizer becomes low, and thus the thickness of the polarizer becomes substantially uniform. Tend to be. Further, the content of the solid content can be determined in consideration of the thickness of the polarizer to be manufactured.

[Polymerization initiator]
The composition for forming a polarizer may contain a polymerization initiator. The polymerization initiator is a compound that can initiate a polymerization reaction of a polymerizable liquid crystal or the like. As the polymerization initiator, a photopolymerization initiator that generates an active radical by the action of light is preferable.

  Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts and sulfonium salts.

  Examples of the benzoin compound include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

  Examples of the benzophenone compound include benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4′-methyldiphenylsulfide, 3,3 ′, 4,4′-tetra (tert-butylperoxycarbonyl) ) Benzophenone and 2,4,6-trimethylbenzophenone.

  Examples of the alkylphenone compound include diethoxyacetophenone, 2-methyl-2-morpholino-1- (4-methylthiophenyl) propan-1-one, and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl ) Butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethan-1-one, 2-hydroxy-2-methyl-1 -[4- (2-hydroxyethoxy) phenyl] propan-1-one, 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propane-1- ON oligomers and the like.

  Examples of the acylphosphine oxide compound include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide.

  Examples of the triazine compound include 2,4-bis (trichloromethyl) -6- (4-methoxyphenyl) -1,3,5-triazine and 2,4-bis (trichloromethyl) -6- (4-methoxy Naphthyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (4-methoxystyryl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6 [2- (5-Methylfuran-2-yl) ethenyl] -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- [2- (furan-2-yl) ethenyl] -1 , 3,5-triazine, 2,4-bis (trichloromethyl) -6- [2- (4-diethylamino-2-methylphenyl) ethenyl] -1,3,5-triazine and 2,4-bis (trichloromethyl Methyl) 6- [2- (3,4-dimethoxyphenyl) ethenyl] -1,3,5-triazine.

  Commercially available polymerization initiators can be used. Commercially available polymerization initiators include Irgacure (registered trademark) 907, 184, 651, 819, 250, and 369 (manufactured by Ciba Specialty Chemicals Co., Ltd.); Sequol (registered trademark) BZ, Z, and BEE (Manufactured by Seiko Chemical Co., Ltd.); Kayacure (registered trademark) BP100 and UVI-6992 (manufactured by Dow Chemical Company); Adeka Optomer SP-152 and SP-170 (manufactured by ADEKA Corporation); TAZ -A and TAZ-PP (manufactured by Nippon Siber Hegner Co., Ltd.); and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.).

  The content of the polymerization initiator in the composition for forming a polarizer can be appropriately adjusted depending on the type and the amount of the polymerizable liquid crystal, and is usually 0.1 to 100 parts by mass based on the content of the polymerizable liquid crystal. It is 30 parts by mass, preferably 0.5 to 10 parts by mass, more preferably 0.5 to 8 parts by mass. When the content of the polymerization initiator is within the above range, polymerization can be performed without disturbing the alignment of the polymerizable liquid crystal.

[Sensitizer]
The composition for forming a polarizer may contain a sensitizer. As the sensitizer, a photosensitizer is preferable. Examples of the sensitizer include xanthone compounds such as xanthone and thioxanthone (eg, 2,4-diethylthioxanthone, 2-isopropylthioxanthone); anthracenes such as anthracene and anthracene containing an alkoxy group (eg, dibutoxyanthracene) Compounds: phenothiazine, rubrene and the like.

  When the polarizer-forming composition contains a sensitizer, the polymerization reaction of the polymerizable liquid crystal contained in the polarizer-forming composition can be further promoted. The amount of the sensitizer used is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and more preferably 0.5 to 8 parts by mass with respect to 100 parts by mass of the polymerizable liquid crystal. Is more preferred.

[Polymerization inhibitor]
From the viewpoint of stably proceeding the polymerization reaction, the composition for forming a polarizer may contain a polymerization inhibitor. The progress of the polymerization reaction of the polymerizable liquid crystal can be controlled by the polymerization inhibitor.

  Examples of the polymerization inhibitor include radicals such as hydroquinone, alkoxy-containing hydroquinone, alkoxy-containing catechol (eg, butyl catechol), pyrogallol, and 2,2,6,6-tetramethyl-1-piperidinyloxy radical. Scavengers; thiophenols; β-naphthylamines and β-naphthols.

  When the polarizer-forming composition contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.1 to 30 parts by mass, more preferably 0 to 30 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal. 0.5 to 10 parts by mass, more preferably 0.5 to 8 parts by mass. When the content of the polymerization inhibitor is within the above range, polymerization can be performed without disturbing the alignment of the polymerizable liquid crystal.

[Leveling agent]
The composition for forming a polarizer may contain a leveling agent. The leveling agent has a function of adjusting the fluidity of the composition for forming a polarizing film and flattening a film obtained by applying the composition for forming a polarizer, and includes, for example, a surfactant. be able to. Preferred leveling agents include polyacrylate compounds such as "BYK-361N" (manufactured by BYK Chemie), and Surflon (registered trademark) "S-381" (manufactured by AGC Seimi Chemical Co., Ltd.). And a leveling agent containing a fluorine atom-containing compound as a main component.

  When the composition for forming a polarizer contains a leveling agent, preferably 0.1 to 5 parts by mass, more preferably 0.3 to 5 parts by mass, and still more preferably 100 parts by mass of the polymerizable liquid crystal. Is 0.5 to 3 parts by mass. When the content of the leveling agent is within the above range, the polymerizable liquid crystal tends to be horizontally aligned, and the obtained polarizer tends to be smoother. If the content of the leveling agent with respect to the polymerizable liquid crystal exceeds the above range, the obtained polarizer tends to have unevenness. In addition, the composition for polarizer formation may contain two or more types of leveling agents.

[Reactive additive]
The composition for forming a polarizer may include a reactive additive. As the reactive additive, those having a carbon-carbon unsaturated bond and an active hydrogen reactive group in the molecule are preferable. Here, the "active hydrogen reactive group" refers to groups which are reactive toward groups having active hydrogen such as carboxyl group (-COOH), a a hydroxyl group (-OH), a amino group (-NH ₂₎ And glycidyl group, oxazoline group, carbodiimide group, aziridine group, imide group, isocyanate group, thioisocyanate group, maleic anhydride group and the like are typical examples. The number of carbon-carbon unsaturated bonds and active hydrogen-reactive groups of the reactive additive is usually 1 to 20, preferably 1 to 10, respectively.

  The reactive additive preferably has at least two active hydrogen-reactive groups. In this case, the plurality of active hydrogen-reactive groups may be the same or different.

  The carbon-carbon unsaturated bond of the reactive additive may be a carbon-carbon double bond or a carbon-carbon triple bond, or a combination thereof, but is preferably a carbon-carbon double bond. Among them, the reactive additive preferably contains a carbon-carbon unsaturated bond as a vinyl group and / or a (meth) acryl group. Further, a reactive additive in which the active hydrogen reactive group is at least one selected from the group consisting of an epoxy group, a glycidyl group and an isocyanate group is preferable, and a reactive additive having an acryl group and an isocyanate group is more preferable. .

  Specific examples of the reactive additive include compounds having a (meth) acrylic group and an epoxy group, such as methacryloxyglycidyl ether and acryloxyglycidyl ether; (meth) acrylic group, such as oxetane acrylate and oxetane methacrylate, and oxetane A compound having a (meth) acrylic group and a lactone group, such as lactone acrylate and lactone methacrylate; a compound having a vinyl group and an oxazoline group, such as vinyl oxazoline and isopropenyl oxazoline; isocyanatomethyl acrylate And oligomers of compounds having a (meth) acrylic group and an isocyanate group, such as isocyanatomethyl methacrylate, 2-isocyanatoethyl acrylate and 2-isocyanatoethyl methacrylate. That. Further, compounds having a vinyl group or a vinylene group and an acid anhydride, such as methacrylic anhydride, acrylic anhydride, maleic anhydride and vinyl maleic anhydride, may be mentioned. Among them, methacryloxyglycidyl ether, acryloxyglycidyl ether, isocyanatomethyl acrylate, isocyanatomethyl methacrylate, vinyl oxazoline, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate and the above oligomers are preferable, and isocyanatomethyl acrylate, 2-isocyanatoethyl acrylate and the aforementioned oligomers are particularly preferred.

  Specifically, a compound represented by the following formula (Y) is preferable.

[In the formula (Y),
n represents an integer of 1 to 10, and R ^{1 ′} is a divalent aliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 5 to 20 carbon atoms. Represents One of two R ^{2 ′ in} each repeating unit is —NH—, and the other is a group represented by> NC (＝ O) —R ^{3 ′} . R ^{3 ′} represents a hydroxyl group or a group having a carbon-carbon unsaturated bond.
Among R ^{3 ′} in the formula (Y), at least one R ^{3 ′} is a group having a carbon-carbon unsaturated bond. ]

  Among the reactive additives represented by the formula (Y), a compound represented by the following formula (YY) (hereinafter sometimes referred to as a compound (YY)) is particularly preferred (n is the same as described above). Meaning).

  As the compound (YY), a commercially available product can be used as it is or may be purified as necessary. Commercially available products include, for example, Laromer (registered trademark) LR-9000 (manufactured by BASF).

  When the polarizer-forming composition contains a reactive additive, the content of the reactive additive is usually 0.01 to 10 parts by mass, preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal. 1 to 5 parts by mass.

<Orientation film>
In the present invention, the alignment film is a film made of a polymer compound and has an alignment regulating force for aligning the polymerizable liquid crystal in a desired direction.

  The alignment film facilitates liquid crystal alignment of the polymerizable liquid crystal. The state of liquid crystal alignment such as horizontal alignment, vertical alignment, hybrid alignment, and tilt alignment changes depending on the properties of the alignment film and the polymerizable liquid crystal, and a combination thereof can be arbitrarily selected. For example, if the alignment film is a material that develops horizontal alignment as an alignment regulating force, the polymerizable liquid crystal can form horizontal alignment or hybrid alignment, and if it is a material that develops vertical alignment, the polymerizable liquid crystal becomes vertical. An oriented or tilted orientation can be formed. Expressions such as horizontal and vertical indicate the direction of the major axis of the aligned polymerizable liquid crystal with respect to the plane of the polarizer. The horizontal alignment is an alignment having a major axis of the aligned polymerizable liquid crystal in a direction parallel to the polarizer plane. Here, “parallel” means an angle of 0 ° ± 20 ° with respect to the polarizer plane. Vertical alignment means having the major axis of the polymerizable liquid crystal aligned in a direction perpendicular to the plane of the polarizer. Here, "perpendicular" means 90 ° ± 20 ° with respect to the polarizer plane.

  The alignment regulating force can be arbitrarily adjusted depending on the surface state and the rubbing condition when the alignment film is formed from the alignment polymer, and the polarization irradiation condition when the alignment film is formed from the photo alignment polymer. It can be arbitrarily adjusted by the above method. Further, by selecting physical properties such as surface tension and liquid crystallinity of the polymerizable liquid crystal, the liquid crystal alignment can be controlled.

  The alignment film formed between the diffusion preventing layer and the polarizer is insoluble in the solvent used when forming the polarizer on the alignment film, and is used for removing the solvent and aligning the liquid crystal. Those having heat resistance in the heat treatment are preferable. Examples of the alignment film include an alignment film made of an alignment polymer, a photo alignment film, a groove alignment film, and the like, and a photo alignment film is preferable.

  The thickness of the alignment film is usually in the range of 10 nm to 500 nm, preferably in the range of 10 nm to 200 nm, and more preferably 30 to 100 nm.

  Examples of the oriented polymer include polyamides and gelatins having an amide bond in the molecule, polyimide having an imide bond in the molecule, and polyamic acid which is a hydrolyzate thereof, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, Examples include polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylates. Among them, polyvinyl alcohol is preferable. These orientation polymers may be used alone or in combination of two or more.

  An alignment film made of an alignment polymer is usually coated with a composition in which an alignment polymer is dissolved in a solvent (hereinafter, also referred to as an “alignment polymer composition”) on a diffusion prevention layer, and the solvent is removed, or It is obtained by applying the oriented polymer composition to the diffusion preventing layer, removing the solvent, and rubbing (rubbing method).

  Examples of the solvent include water; alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone; Ester solvents such as propylene glycol methyl ether acetate and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; Aromatic hydrocarbon solvents such as xylene; nitrile solvents such as acetonitrile; tetrahydrofuran and dimethyl alcohol Ether solvents such as Kishietan; chloroform and chlorinated hydrocarbon solvents such as chlorobenzene; and the like. These solvents may be used alone or in combination of two or more.

  The concentration of the orienting polymer in the orienting polymer composition may be within a range in which the orienting polymer can be completely dissolved in the solvent, but is preferably 0.1 to 20% by mass in terms of solid content with respect to the solution. 1-10 mass% is more preferable.

  As the alignment polymer composition, a commercially available alignment film material may be used as it is. Examples of commercially available alignment film materials include Sanever (registered trademark) (manufactured by Nissan Chemical Industries, Ltd.) and Optmer (registered trademark) (manufactured by JSR Corporation).

  As a method of applying the oriented polymer composition to the diffusion prevention layer, there are spin coating method, extrusion method, gravure coating method, die coating method, bar coating method, bar coating method, applicator method and the like, and printing such as flexo method. Publicly known methods, such as a method. When the polarizing plate is manufactured by a roll-to-roll continuous manufacturing method, a printing method such as a gravure coating method, a die coating method, or a flexo method is usually used as the coating method.

  By removing the solvent contained in the oriented polymer composition, a dried film of the oriented polymer is formed. Examples of the method for removing the solvent include a natural drying method, a ventilation drying method, a heating drying method, and a reduced-pressure drying method.

  As a method of rubbing, a rubbing cloth is wound around, and a rotating rubbing roll is coated with an oriented polymer composition on the diffusion prevention layer, and annealed, and a film of the oriented polymer formed on the diffusion prevention layer surface is annealed. Are brought into contact with each other.

  The photo-alignment film is generally coated with a composition containing a polymer or monomer having a photoreactive group and a solvent (hereinafter, also referred to as a “composition for forming a photo-alignment film”) on a diffusion preventing layer, and polarized light (preferably, (Polarized light UV). The photo-alignment film is more preferable in that the direction of the alignment regulating force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

  The photoreactive group refers to a group that generates liquid crystal alignment ability when irradiated with light. Specifically, it generates a photoreaction that is the origin of the liquid crystal alignment ability, such as an orientation-induced or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photodecomposition reaction of molecules caused by irradiation with light. is there. Among the photoreactive groups, those that cause a dimerization reaction or a photocrosslinking reaction are preferable in terms of excellent orientation. As the photoreactive group capable of causing the above reaction, those having an unsaturated bond, particularly a double bond are preferable, and a carbon-carbon double bond (C = C bond) and a carbon-nitrogen double bond (C = N bond), a nitrogen-nitrogen double bond (N = N bond), and a group having at least one selected from the group consisting of a carbon-oxygen double bond (C = O bond).

  Examples of the photoreactive group having a C ＝ C bond include a vinyl group, a polyene group, a stilbene group, a stilbazol group, a stilbazolium group, a chalcone group, and a cinnamoyl group. Examples of the photoreactive group having a C ＝ N bond include groups having a structure such as an aromatic Schiff base and an aromatic hydrazone. Examples of the photoreactive group having an N = N bond include an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group, a formazan group, and the like, and a group having azoxybenzene as a basic structure. Examples of the photoreactive group having a C ＝ O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have a substituent such as an alkyl group, an alkoxy group, an aryl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group, and a halogenated alkyl group.

  As the solvent for the composition for forming a photo-alignment film, a solvent that dissolves a polymer and a monomer having a photoreactive group is preferable. Examples of the solvent include the solvents mentioned as the solvent for the above-described alignment polymer composition. Is mentioned.

  The content of the polymer or monomer having a photoreactive group with respect to the composition for forming a photoalignment film can be appropriately adjusted depending on the type of the polymer or monomer having the photoreactive group or the thickness of the photoalignment film to be produced. Is preferably at least 0.2% by mass, and particularly preferably from 0.3 to 10% by mass. Further, a polymer material such as polyvinyl alcohol and polyimide or a photosensitizer may be contained as long as the properties of the photo-alignment film are not significantly impaired.

  Examples of a method for applying the composition for forming a photo-alignment film to the diffusion prevention layer include the same method as the method for applying the alignment polymer composition to the diffusion prevention layer. The method for removing the solvent from the applied composition for forming a photo-alignment film includes, for example, the same method as the method for removing the solvent from the oriented polymer composition.

  In order to irradiate polarized light, even in a form in which the solvent is removed directly from the composition for forming a photo-alignment film applied on the diffusion preventing layer or the like and the solvent is removed, the polarized light is irradiated from the diffusion preventing layer side. Alternatively, the light may be transmitted through polarized light for irradiation. It is particularly preferable that the polarized light is substantially parallel light. The wavelength of the polarized light to be irradiated is preferably in a wavelength region where the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet light) in the wavelength range of 250 to 400 nm is particularly preferred. Examples of the light source used for the polarized light irradiation include a xenon lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, an ultraviolet laser such as KrF and ArF, and a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp. preferable. These lamps are preferable because of their high emission intensity of ultraviolet light having a wavelength of 313 nm. Polarized light can be emitted by irradiating the light from the light source through an appropriate polarizer. As such a polarizer, a polarizing filter, a polarizing prism such as Glan-Thompson or Glan-Taylor, or a wire grid type polarizer can be used.

  Note that a plurality of regions (patterns) having different directions of liquid crystal alignment can be formed by performing masking when performing rubbing or irradiation with polarized light.

  The groove alignment film is a film having an uneven pattern or a plurality of grooves (grooves) on the film surface. When liquid crystal molecules are placed on a film having a plurality of linear grubs arranged at equal intervals, the liquid crystal molecules are oriented in a direction along the grooves.

  As a method of obtaining the grub alignment film, a method of forming an uneven pattern by performing exposure and development and rinsing treatment after exposure through an exposure mask having a pattern-shaped slit on the photosensitive polyimide film surface, a plate having grooves on the surface Method of forming a layer of a UV-curable resin before curing on a plate-shaped master, transferring the resin layer to a diffusion prevention layer and then curing, and a film of a UV-curable resin before curing formed on the diffusion prevention layer In addition, a method of pressing a roll-shaped master having a plurality of grooves to form irregularities and then curing the same is given. Specific examples include the methods described in JP-A-6-34976 and JP-A-2011-242743.

  In order to obtain a small orientation disorder, the width of the convex portion of the grub alignment film is preferably 0.05 μm to 5 μm, and the width of the concave portion is preferably 0.1 μm to 5 μm. The depth is preferably 2 μm or less, and more preferably 0.01 μm to 1 μm.

<Diffusion prevention layers A and B>
The polarizing plate has a diffusion prevention layer (diffusion prevention layer A) on one side of the polarizer and another diffusion prevention layer (diffusion prevention layer B) on the other side. In the polarizing plate, preferably, the diffusion preventing layer A or B is in contact with the polarizer, and more preferably, both the diffusion preventing layers A and B are in contact with the polarizer. The diffusion preventing layers A and B are layers that can suppress the movement of the dichroic dye from the polarizer, and as a result, can prevent the polarization performance of the polarizer from decreasing over time. Further, since the thickness of each of the diffusion preventing layers A and B is 20 μm or less, the thickness of the polarizing plate can be reduced. When the polarizing plate has the diffusion preventing layers A and B, when the polarizing plate is laminated on another member (adherend), even if the other member has a step (unevenness) in the shape, the polarizer is used. Since the film thickness fluctuation can be reduced, uniform polarization performance in the film can be obtained. In this specification, the adherend means a member to be transferred when the polarizing plate is transferred from the substrate, and a member to be stacked when the polarizing plate is stacked without being transferred. Examples of such a member include members to which a polarizing plate is applied, such as a front plate and a retardation film.
Further, the diffusion preventing layers A and B preferably contribute to prevention of shrinkage and expansion of the polarizer and prevention of deterioration of the polarizer due to temperature, humidity, ultraviolet rays, and the like.

  As a material constituting the diffusion prevention layers A and B, a material having excellent solvent resistance, transparency, mechanical strength, thermal stability, shielding property, isotropy, and the like is preferable. It suffices if it has at least transparency enough to withstand use as a polarizing plate and diffusion prevention ability for suppressing movement of dichroic dyes.

  The diffusion preventing layers A and B having the function of preventing movement (diffusion) of the dichroic dye are preferably made of a material having low compatibility with the dichroic dye. Such materials include photocurable resins and water-soluble polymers. Since the photocurable resin is highly polymerized, the diffusion of the dichroic dye can be prevented, and the polarity of the water-soluble polymer is significantly different from that of the dichroic dye, so that the diffusion of the dichroic dye can be prevented.

At least one selected from the group consisting of the diffusion preventing layers A and B is, specifically, a polyacrylamide-based polymer; polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, (meth) acrylic acid or its anhydride-vinyl. It is preferable to include a water-soluble polymer such as a vinyl alcohol polymer such as an alcohol copolymer; a carboxyvinyl polymer; a polyvinyl pyrrolidone; a starch; a sodium alginate; or a polyethylene oxide polymer. It is preferable that at least one selected from the group consisting of the diffusion preventing layers A and B contains a photocurable resin such as an acrylic, urethane, acrylic urethane, epoxy, or silicone resin.
Among them, from the viewpoint of being more excellent in the function of shielding the dichroic dye in the polarizer, it is preferable that at least one selected from the group consisting of the diffusion prevention layers A and B contains a water-soluble polymer, and one of the diffusion prevention layers is water-soluble. It is preferable that the other diffusion-preventing layer contains a photocurable resin. The material forming the diffusion prevention layer A and the material forming the diffusion prevention layer B may be the same or different. Further, the diffusion preventing layer A and the diffusion preventing layer B may be the same or different. In this specification, the term “diffusion prevention layer” may be simply used, which means that the diffusion prevention layer may be either the diffusion prevention layer A or the diffusion prevention layer B.

  The content of the polymer in the diffusion prevention layers A and B is preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably 99% by mass or more. Further, the diffusion preventing layers A and B may contain the above polymer alone or in combination of two or more.

  The glass transition temperature of the diffusion preventing layers A and B is preferably higher than 25 ° C. (room temperature), and is preferably 40 ° C. or higher. Further, the glass transition temperature of the polymer constituting the diffusion preventing layer A or B is preferably 25 ° C. (room temperature) or higher, and more preferably 40 ° C. or higher. That is, the diffusion prevention layers A and B are preferably layers cured at room temperature. With such a layer, the diffusion of the dichroic dye into the diffusion preventing layers A and B can be prevented, and the deterioration over time of the optical performance of the polarizing plate can be further reduced.

  Further, the content of the low-molecular compound having a molecular weight of 1000 or less in the diffusion preventing layers A and B is preferably 1% by mass or less, and more preferably 0.1% by mass or less. With such a layer, the diffusion of the dichroic dye into the diffusion preventing layers A and B can be prevented, and the deterioration over time of the optical performance of the polarizing plate can be further reduced.

  Each of the diffusion preventing layers A and B preferably has good adhesion to an adherend, can adhere a polarizing plate to a desired region, and is preferably a layer used for laminating a polarizing plate. According to such diffusion preventing layers A and B, the polarizing plate can be directly laminated on the adherend, so that the thickness of the obtained laminate can be reduced. Examples of the polymer constituting the diffusion preventing layer, which has adhesiveness to the adherend, include a vinyl alcohol polymer and at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, an amide crosslinking agent, and an acrylic crosslinking agent. And a mixture composition of the same.

The thickness of each of the diffusion preventing layers A and B is 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less, and still more preferably 5 μm or less. The thickness of each of the diffusion preventing layers A and B is preferably 0.05 μm or more. The thickness of at least one of the diffusion preventing layers A and B, particularly the thickness of each of the diffusion preventing layers A and B, is preferably in the above range, but a more preferable range is 0.05 μm to 5 μm. Yes, more preferably 0.05 μm to 3 μm, even more preferably 0.5 μm to 3 μm. Particularly, when the pressure-sensitive adhesive layer is provided on the surface of the diffusion prevention layer A or B opposite to the polarizer, at least one of the diffusion prevention layers A or B has a thickness of at least one of A and B of the diffusion prevention layer. Each thickness of B is preferably 0.5 μm to 20 μm, more preferably 0.5 μm to 10 μm, further preferably 0.5 μm to 5 μm, and particularly preferably 0.5 μm to 3 μm. . In this case, when the diffusion preventing layer has a thickness of 0.5 μm or more, the movement of the dichroic dye to the pressure-sensitive adhesive layer can be sufficiently suppressed. When the pressure-sensitive adhesive layer is not formed on the surface of the diffusion prevention layer opposite to the polarizer, the diffusion prevention layer has a thickness of 0.05 μm to 3 μm to move the dichroic dye to the pressure-sensitive adhesive layer. Can be sufficiently suppressed.
The thickness of the diffusion preventing layer A and the thickness of the diffusion preventing layer B may be the same or different. The diffusion preventing layers A and B may each be a single layer, or may be composed of a plurality of layers.

  The diffusion preventing layers A and B may have a surface treatment layer on the surface opposite to the polarizer. Examples of the surface treatment layer include optical layers such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, an anti-glare layer, and a diffusion layer.

  The hard coat layer is for the purpose of preventing the polarizing plate surface from being scratched, for example, by adding a cured film having excellent hardness and sliding properties to the surface of the diffusion prevention layer by using an ultraviolet-curable resin such as an acrylic or silicone resin. It can be formed by a method or the like. The anti-reflection layer is intended to prevent reflection of external light on the polarizing plate surface, and can be achieved by forming an anti-reflection film or the like according to the related art. Further, the anti-sticking layer is intended to prevent adhesion to a layer which is in contact with the anti-sticking layer.

  The anti-glare layer is provided for the purpose of preventing external light from being reflected on the surface of the polarizing plate and hindering the visibility of light transmitted through the polarizing plate. For example, the anti-glare layer is roughened by a sandblasting method or an embossing method. It can be formed by providing a fine uneven structure on the surface of the diffusion preventing layer by a method such as a method or a method of blending transparent fine particles. Examples of the fine particles contained for forming the surface fine unevenness include silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle diameter of 0.5 to 50 μm. Transparent fine particles such as inorganic fine particles that can have conductivity and organic fine particles made of a crosslinked or uncrosslinked polymer or the like can be given. When forming the fine surface unevenness structure, the content of the fine particles is usually 2 to 50 parts by mass, preferably 5 to 25 parts by mass with respect to 100 parts by mass of the transparent resin forming the fine surface unevenness structure. The anti-glare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for expanding the viewing angle or the like by diffusing light transmitted through the polarizing plate.

  The anti-reflection layer, anti-sticking layer, diffusion layer, anti-glare layer and the like can be provided on the diffusion prevention layer itself and integrated therewith, or separately provided as an optical layer separately from the diffusion prevention layer. Can also.

The anti-diffusion layers A and B are usually prepared by using a solution of a material constituting each anti-diffusion layer (hereinafter, also referred to as “diffusion-prevention layer composition”) as a substrate, an alignment film, a polarizer, a front plate, or the like. It is obtained by applying to a member and curing.
When the composition of the diffusion prevention layer is a composition in which the material constituting the diffusion prevention layer is dissolved in a solvent, the material constituting the diffusion prevention layer may be cured by removing the solvent, and the solvent may be removed. After that, it may be further cured through a chemical reaction.
The anti-diffusion layer composition may be applied on the above-mentioned member and cured, or after being applied on the above-mentioned member, another member may be laminated thereon and cured.

  The solvent may be any solvent that dissolves the material constituting the diffusion prevention layer, and examples thereof include the solvents mentioned as the solvent for the above-mentioned oriented polymer composition.

  The concentration of the material constituting the diffusion preventing layer in the composition of the diffusion preventing layer is preferably 0.1 to 20% by mass, more preferably 0.1 to 10% by mass in terms of solid content.

  Examples of the method of applying the composition of the diffusion preventing layer to the substrate and the method of removing (drying) the solvent include the same methods as those described for the above-mentioned oriented polymer composition.

  The anti-diffusion layer is appropriately selected from the above-listed materials, in addition to being provided on the polarizer to prevent the transfer of the dichroic dye, to be used for any of the layers containing an active energy ray-curable resin. Can also. The diffusion preventing layer may be formed, for example, on at least one side surface of a retardation layer made of a liquid crystal polymerizable compound. In this case, the diffusion preventing layer can function to prevent impact or cracks due to bending.

<Manufacturing method of polarizing plate>
The polarizing plate can be manufactured, for example, by the method described in JP-A-2017-83843. The polarizing plate may be manufactured by bonding sheet-shaped members cut into a predetermined shape to each other, or may be manufactured by bonding long members to each other.

<Adhesive layer>
The polarizing plate may have a pressure-sensitive adhesive layer on the side of the diffusion preventing layer opposite to the polarizer side. The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive. By the pressure-sensitive adhesive layer, the adhesion of the polarizing plate to the adherend is improved, and a polarizing function derived from the polarizer can be easily imparted to a desired region.

  The adhesive usually contains a polymer and may further contain a solvent. Examples of the polymer include an acrylic polymer, a silicone polymer, polyester, polyurethane, and polyether. Among them, acrylic pressure-sensitive adhesives containing acrylic polymers have excellent optical transparency, moderate wettability and cohesion, excellent adhesion, and high weather resistance and heat resistance. Floating, peeling, etc. are unlikely to occur under conditions of humidification or humidification.

  As the acrylic polymer, a (meth) acrylate in which the alkyl group in the ester portion is an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group, or a butyl group (hereinafter, acrylate and methacrylate are collectively referred to as (meth) (Acrylate, acrylic acid and methacrylic acid are sometimes collectively referred to as (meth) acrylic acid.) And (meth) acrylic monomers having a functional group such as (meth) acrylic acid and hydroxyethyl (meth) acrylate. Are preferred.

  The pressure-sensitive adhesive containing such a copolymer is excellent in tackiness, and is also relatively easily removed without causing glue residue or the like on the display device when it is removed after bonding to the display device. It is possible. The glass transition temperature of the acrylic polymer is preferably 25 ° C. or lower, more preferably 0 ° C. or lower. The weight average molecular weight of such an acrylic polymer is preferably 100,000 or more.

  Examples of the solvent include the solvents mentioned above as the solvent for the oriented polymer composition.

The pressure-sensitive adhesive has a storage elastic modulus at 25 ° C. of preferably 1 × 10 ⁶ Pa (1 MPa) or less, more preferably 5 × 10 ⁵ Pa (0.5 MPa) or less, and more preferably 3 × 10 ⁵ Pa. (0.3 MPa) or less. When the storage elastic modulus is 1 × 10 ⁶ Pa (1 MPa) or less, it is preferable because air bubbles are less likely to be generated due to bending, and display unevenness is less likely to occur. Further, the storage elastic modulus is preferably 1 × 10 ⁴ Pa (0.01 MPa) or more, more preferably 2 × 10 ⁴ Pa (0.02 MPa) or more, and 3 × 10 ⁴ Pa (0.03 MPa). ) Is more preferable. It is preferable that the storage elastic modulus is 1 × 10 ⁴ Pa (0.01 MPa) or more, since the adhesive tends to hardly adhere to other parts during the manufacturing operation. The storage elastic modulus of the adhesive at 80 ° C. is preferably 5 × 10 ⁵ Pa (0.5 MPa) or less, more preferably 3 × 10 ⁵ Pa (0.3 MPa) or less, and 1 × 10 ⁵ Pa (0.1 MPa). ) Is more preferably 5 × 10 ⁴ Pa (0.05 MPa) or less, particularly preferably 3 × 10 ⁴ Pa (0.03 MPa) or less. When the storage elastic modulus at 80 ° C. is 5 × 10 ⁵ Pa (0.5 MPa) or less, the fluidity in the heating operation is good, and the generation of bubbles and the like tend to be suppressed, which is preferable.

  Among the adhesive layers formed on the side opposite to the polarizer side in the diffusion prevention layer, the storage elastic modulus at 25 ° C. of the adhesive forming the adhesive layer disposed between the front plate and the polarizing plate is as follows: It is 0.6 MPa or less. This storage elastic modulus is more preferably 0.5 MPa or less, more preferably 0.1 MPa or less, and preferably 0.01 MPa or more. The front plate and the polarizing plate are laminated with the pressure-sensitive adhesive having the above storage elastic modulus, so that stress generated in the diffusion preventing layer and the retardation film when the polarizing plate with the front plate is bent can be reduced. . The flexibility of the polarizing plate with the front plate is easily improved. In addition, the storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive is measured by a method described in Examples described later.

  Further, the pressure-sensitive adhesive may contain a light diffusing agent. The light diffusing agent is for imparting light diffusing property to the pressure-sensitive adhesive, and may be fine particles having a refractive index different from that of the polymer contained in the pressure-sensitive adhesive.As the light diffusing agent, fine particles made of an inorganic compound and Fine particles made of an organic compound (polymer) may be used. Most of the polymers contained in the pressure-sensitive adhesive as an active ingredient, including the acrylic polymer, have a refractive index of about 1.4, so that the light diffusing agent is appropriately selected from those having a refractive index of about 1 to 2. do it. The difference in refractive index between the polymer containing the adhesive as an active ingredient and the light diffusing agent is usually 0.01 or more, and from the viewpoint of brightness and displayability of the display device, 0.01 or more and 0.5 or less. It is preferred to do so. The fine particles used as the light diffusing agent are preferably spherical and those which are close to monodisperse. For example, fine particles having an average particle diameter in the range of about 2 to 6 μm are suitably used.

  The refractive index is measured by a general minimum declination method or Abbe refractometer.

  Examples of the fine particles made of an inorganic compound include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45).

  Examples of the fine particles composed of an organic compound (polymer) include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), and methyl methacrylate / styrene copolymer resin beads (refractive index 1). .50-1.59), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1.46), And silicone resin beads (refractive index: 1.46).

  The compounding amount of the light diffusing agent is appropriately determined in consideration of the haze value required for the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive and the brightness of a display device to which the pressure-sensitive adhesive layer is applied. Is 3 to 30 parts by mass with respect to the content of 100 parts by mass.

  The haze value of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive in which the light diffusing agent is dispersed, while ensuring the brightness of the display device to which the polarizing plate is applied, from the viewpoint of preventing blurring and blurring of the display image. It is preferable to set it in the range of 20 to 80%. The haze value is a value represented by (diffuse transmittance / total light transmittance) × 100 (%), and is measured according to JIS K 7105.

  The thickness of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive is determined according to the adhesive strength and the like, and is not particularly limited, but is usually 1 to 40 μm. From the viewpoints of workability, durability and the like, the thickness is preferably 5 to 25 μm, more preferably 5 to 15 μm. When the thickness of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive is about 5 to 15 μm, the adherend and the polarizer can be sufficiently bonded, and the display can be made thinner as a whole.

<Front plate>
The polarizing plate includes a front plate disposed on the side of the diffusion prevention layer opposite to the polarizer. The front plate may be laminated on the polarizing plate via an adhesive layer or a diffusion preventing layer.

  The front plate plays a role of suppressing a warp of an image display element such as a liquid crystal cell and protecting the image display element, and is, for example, a translucent (preferably optically transparent) plate-like body. It is. The front plate may have a single-layer structure or a multilayer structure.

Since the front plate is disposed on the outermost surface of the final product, it is required to have sufficient durability even when used outdoors or semi-outdoors. Further, the front plate is required to have durability against bending. From such a viewpoint, the front plate is preferably made of a polymer film having a tensile modulus of 2 GPa or more. The front plate preferably contains a resin film for flexible display applications. Among the resin films, polycarbonate resin (tensile elastic modulus of 2 to 3 GPa), acrylic resin (tensile elastic modulus of 3 to 4 GPa), and polyimide resin (tensile modulus) It is particularly preferred to be composed of a polyamide resin (tensile elasticity of 3 to 8 GPa), a polyamide resin (tensile elasticity of 3 to 13 GPa), a polyether sulfone resin (tensile elasticity of 2 to 3 GPa). .
From the viewpoint of reducing the thickness, weight, and flexibility of the display, an acrylic resin, a laminated film having a scratch resistance imparted to the resin, or an organic resin such as a polyimide, polyamide, or a hybrid film containing polyamideimide and silica is preferred. Composite materials of materials and inorganic materials are preferred.
In particular, as a display member or a front plate of a flexible device, a hybrid film containing a polyimide-based polymer or a polyamide-based polymer and silica is more preferable from the viewpoint of flexibility and visibility.

  The integration of the front plate and the polarizing plate can be realized by laminating them via an adhesive layer as necessary. As the pressure-sensitive adhesive layer, those described above can be used. When the polarizing plate includes an adhesive layer, to eliminate reflection or light scattering at the interface between the front plate and the polarizing plate, and to improve visibility, the refractive index of the adhesive is close to the refractive index of the front plate or It is preferably the same as this, and it is preferably optically transparent. The pressure-sensitive adhesive layer can also appropriately adjust viscoelasticity, for example, storage elastic modulus at 25 ° C., tan δ, stress relaxation rate, and the like.

  ADVANTAGE OF THE INVENTION The polarizing plate with a front plate of this invention can suppress the warpage of an image display element, such as a liquid crystal cell, and can prevent the image display element from being damaged. Furthermore, when the front plate is a flexible form (polymer film), the polarizing plate with a front plate of the present invention is more preferable in that continuous production by roll-to-roll is possible.

  Details will be described with reference to FIG. 4 as one embodiment of the front plate. One preferred embodiment of the front plate is a laminated film in which a functional film is provided on at least one surface of a resin film containing a polyimide-based polymer or a polyamide-based polymer.

(Resin film)
The resin contained in the resin film 40 may be a polyimide polymer or a polyamide polymer. The polyimide-based polymer is, for example, a condensation type polyimide obtained by polycondensation using diamines and tetracarboxylic dianhydride as starting materials. As the polyimide, a polyimide soluble in a solvent used for forming a resin film can be selected. For example, those described in JP-A-2006-93992 can be mentioned. Further, polyamide and polyamide imide can also be suitably used. Examples of the polyamide include those described in JP-A-2011-12255. Examples of the polyamideimide include those described in WO2018 / 135431 and JP-T-2014-528490.

  The resin film 40 may further contain an inorganic material such as inorganic particles. The inorganic material is preferably a silicon material containing a silicon atom. When the resin film 40 contains an inorganic material such as a silicon material, the tensile modulus of the resin film 40 can be easily set to 4.0 GPa or more. However, the method of controlling the tensile modulus of the resin film 40 is not limited to the blending of the inorganic material.

  Examples of the silicon material containing a silicon atom include silica particles, quaternary alkoxysilanes such as tetraethyl orthosilicate (TEOS), and silicon compounds such as silsesquioxane derivatives. Among these silicon materials, silica particles are preferable from the viewpoint of the transparency and flexibility of the resin film 40.

  The average primary particle diameter of the silica particles is usually 100 nm or less. When the average primary particle diameter of the silica particles is 100 nm or less, transparency tends to be improved.

  The average primary particle diameter of the silica particles in the resin film can be determined by observation with a transmission electron microscope (TEM). The primary particle diameter of the silica particles may be a fixed diameter measured by a transmission electron microscope (TEM). The average primary particle diameter can be determined as an average value by measuring the primary particle diameter at 10 points by TEM observation. The particle distribution of the silica particles before forming the resin film can be determined by a commercially available laser diffraction type particle size distribution meter.

  In the resin film 40, the mixing ratio of the polyimide-based polymer or the polyamide-based polymer to the inorganic material is preferably 1: 9 to 10: 0, and the mass ratio is preferably 1: 9 to 10: 0, with the sum of both being 10: 3: 7. The ratio is more preferably from 10 to 0: 0, further preferably from 3: 7 to 8: 2, and still more preferably from 3: 7 to 7: 3. The ratio of the inorganic material to the total mass of the polyimide-based polymer or polyamide-based polymer and the inorganic material is usually 20% by mass or more, preferably 30% by mass or more, and usually 90% by mass or less, and preferably 70% by mass or less. % By mass or less. When the compounding ratio of the polyimide-based polymer or the polyamide-based polymer and the inorganic material (silicon material) is within the above range, the transparency and mechanical strength of the resin film tend to be improved. Further, the tensile modulus of the resin film 40 can be easily set to 4.0 GPa or more.

  The resin film 40 may further contain components other than the polyimide-based polymer or the polyamide-based polymer and the inorganic material as long as the transparency and the flexibility are not significantly impaired. Components other than polyimide-based polymers, polyamide-based polymers, and inorganic materials include, for example, antioxidants, release agents, stabilizers, coloring agents such as bluing agents, flame retardants, lubricants, thickeners and leveling agents. Is mentioned. The proportion of components other than the polyimide polymer or the polyamide polymer and the inorganic material is preferably more than 0% and not more than 20% by mass, more preferably more than 0%, based on the mass of the resin film 40. 10% by mass or less.

  When the resin film 40 contains a polyimide-based polymer or a polyamide-based polymer and a silicon material, Si / N, which is the atomic ratio of silicon atoms to nitrogen atoms, on at least one main surface 40a, may be 8 or more. preferable. The atomic ratio Si / N is obtained by evaluating the composition of the main surface 10a by X-ray photoelectron spectroscopy (X-ray Photoelectron Spectroscopy, XPS), and calculating from the abundance of silicon atoms and abundance of nitrogen atoms obtained thereby. This is a calculated value.

  When the Si / N ratio on the main surface 40a of the resin film 40 is 8 or more, sufficient adhesion to the functional layer 50 described later can be obtained. From the viewpoint of adhesiveness, Si / N is more preferably 9 or more, further preferably 10 or more, preferably 50 or less, and more preferably 40 or less.

  The thickness of the resin film 40 is appropriately adjusted depending on the flexible device to which the front plate (4) is applied, but is usually 10 to 500 μm, preferably 15 to 200 μm, and more preferably 20 to 100 μm. Is more preferable, and it is further preferable that it is 30-100 micrometers. The thickness of the resin film 40 is more preferably 40 to 100 μm, most preferably 40 to 90 μm, and 30 to 70 μm. The resin film 40 having such a configuration has particularly excellent flexibility and practically sufficient strength.

  Next, an example of a method for manufacturing the resin film 40 of the present embodiment will be described. The polyimide polymer varnish used for the production of the resin film is prepared by dissolving a solvent-soluble polyimide polymer polymerized by a known polyimide polymer synthesis method in a solvent. The solvent may be any solvent that dissolves the polyimide-based polymer, for example, N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), γ-butyrolactone (GBL) And a mixed solvent thereof.

  When producing a resin film containing an inorganic material, the inorganic material is added to a polyimide-based polymer varnish, and the mixture is stirred and mixed by a known stirring method to prepare a dispersion in which the silicon material is uniformly dispersed. When blending an ultraviolet absorber, an ultraviolet absorber can be added to this dispersion.

  The polyimide-based polymer varnish or dispersion liquid may include a metal alkoxide such as an alkoxysilane that contributes to bonding between inorganic particles (eg, silica particles). By using a dispersion containing such a compound, the blending ratio of the inorganic particles can be increased while maintaining optical properties such as transparency of the resin film. This compound is preferably an alkoxysilane having an amino group. Such a combination of the compound and the inorganic particles can achieve a high elastic modulus and contribute to increasing the number of times of bending before the resin film is broken in a bending test.

  The polyimide-based polymer varnish or dispersion may further contain water. The content of water is usually 0.1 to 10% by mass based on the mass of the polyimide polymer varnish or dispersion. The use of water can also contribute to achieving a high elastic modulus and increasing the number of bendings before the resin film breaks in a bending test.

  The polyimide polymer or the dispersion may further contain an additive. Examples of the additives include antioxidants, release agents, stabilizers, coloring agents such as bluing agents, flame retardants, lubricants, thickeners, and leveling agents.

  The resin film can be manufactured by an appropriate known method. Examples of the manufacturing method include the following method. The above-mentioned polyimide polymer varnish or dispersion is applied to a substrate by, for example, a known roll-to-roll or batch system to form a coating film. The coating is dried to form a film. Then, the resin film 10 is obtained by peeling the film from the base material. Examples of the substrate include a polyethylene terephthalate (PET) substrate, a stainless steel (SUS) belt, and a glass substrate.

  The coating may be heated for drying and / or baking the coating. The heating temperature of the coating film is usually from 50 to 350C. The coating may be heated under an inert atmosphere or under reduced pressure. By heating the coating, the solvent can be evaporated and removed. The resin film may be formed by a method including a step of drying the coating film at 50 to 150 ° C and a step of baking the dried coating film at 180 to 350 ° C.

At least one main surface of the resin film may be subjected to a surface treatment. The surface treatment is preferably a UV ozone treatment. By UV ozone treatment, Si / N can be easily increased to 8 or more. However, the method of setting Si / N to 8 or more is not limited to UV ozone treatment.
The main surface 10a and / or 10b of the resin film 10 may be subjected to a surface treatment such as a plasma treatment or a corona discharge treatment in order to improve the adhesion with a functional layer described later.

  The UV ozone treatment can be performed using a known ultraviolet light source having a wavelength of 200 nm or less. Examples of the ultraviolet light source include a low-pressure mercury lamp. As the ultraviolet light source, various commercially available devices equipped with an ultraviolet light source may be used. As a commercially available apparatus, for example, an ultraviolet (UV) ozone cleaning apparatus UV-208 manufactured by Technovision Corporation may be mentioned.

  The tensile modulus of the resin film 40 at 25 ° C. is, for example, 4.0 GPa or more, preferably 5 GPs or more, more preferably 5 GPa or more, and preferably 10 GPa or less, and preferably 8 GPa or less. Is more preferred. When the tensile modulus is within these numerical ranges, an excellent effect can be obtained not only in terms of improving surface hardness but also in terms of flexural recovery.

In a bending test in which the distance between the resin films facing the resin film 40 is 3 mm (radius 1.5R), the number of times the resin film 10 is bent until the resin film 40 is broken is repeated in a bending test in which the resin film 40 is repeatedly bent and returned to a U-shape. , Preferably more than 100,000. In the bending test, "the resin film is broken" means that the resin film is partially or totally broken, that is, a part that is divided over the whole in the thickness direction is generated. If the resin film does not break when the number of bending reaches 100,000, the number of bending before the resin film breaks is considered to exceed 100,000. According to the findings of the present inventors, the contribution of the resin film to the improvement in surface hardness can be evaluated based on a bending test up to 100,000 bending times. The details of the bending test will be described in Examples below.

The yellowness (YI value) of the resin film 40 is preferably 5 or less, more preferably 4 or less, still more preferably 3 or less, from the viewpoint of the visibility of the flexible device and the like. The yellowness of the resin film 40 is usually 0.5 or more, and may be 1 or more.
(Functional layer)
The front plate (4) can be composed of a resin film 40 and a functional layer 50 laminated on at least one main surface 40a of the resin film 40.

  The functional layer 50 is preferably a layer having at least one function selected from the group consisting of ultraviolet absorption, high surface hardness, hue adjustment and refractive index adjustment.

  The layer having an ultraviolet absorbing function (ultraviolet absorbing layer) as the functional layer 50 is, for example, a main material selected from an ultraviolet curable transparent resin, an electron beam curable transparent resin, and a thermosetting transparent resin; And an ultraviolet absorber dispersed in the main material. By providing an ultraviolet absorbing layer as the functional layer 50, a change in yellowness due to light irradiation can be easily suppressed.

  The ultraviolet-curable, electron-beam-curable, or thermosetting transparent resin as a main material of the ultraviolet-absorbing layer is not particularly limited, and examples thereof include poly (meth) acrylate.

  The ultraviolet absorbing layer may be a layer that absorbs 95% or more of light having a wavelength of 400 nm or less (for example, light having a wavelength of 313 nm). In other words, the ultraviolet absorbing layer may be a layer having a transmittance of less than 5% for light having a wavelength of 400 nm or less (for example, light having a wavelength of 313 nm). The ultraviolet absorbing layer may include an ultraviolet absorbing agent at a concentration that allows such transmittance. From the viewpoint of suppressing an increase in the yellowness of the front panel due to light irradiation, the content ratio of the ultraviolet absorber in the ultraviolet absorbing layer (functional layer 50) is usually 1% by mass or more based on the mass of the ultraviolet absorbing layer. And preferably 3% by mass or more, usually 10% by mass or less, and more preferably 8% by mass or less.

  The functional layer (hard coat layer) that expresses high hardness on the surface as the functional layer 50 is, for example, a layer that gives the laminate a surface having a pencil hardness higher than the pencil hardness of the surface of the resin film. The hard coat layer includes, but is not particularly limited to, an active energy ray-curable or thermosetting radical-curable composition or a cationic-curable composition represented by poly (meth) acrylates. The hard coat layer may include a photopolymerization initiator and an organic solvent. As the radical curing composition, the poly (meth) acrylates are, for example, one or more (meth) acrylates selected from polyurethane (meth) acrylate, epoxy (meth) acrylate and other polyfunctional poly (meth) acrylates It is preferably a poly (meth) acrylate formed from The cationically curable composition includes a compound having a cationically polymerizable group such as an epoxy group, an oxetanyl group, and a vinyl ether group. It is preferable to include a polyfunctional compound having two or more cationically polymerizable groups in the molecule. The hard coat layer may contain an inorganic oxide such as silica, alumina, and polyorganosiloxane in addition to the above components. The pencil hardness of the functional layer (hard coat layer) exhibiting high hardness on the surface is preferably 2H or more, more preferably 3H or more.

  The layer having a hue adjustment function (hue adjustment layer) as the functional layer 50 is a layer that can adjust the front plate (4) to a target hue. The hue adjustment layer may be, for example, a layer containing a resin and a colorant. Examples of the coloring agent include inorganic pigments such as titanium oxide, zinc oxide, red iron oxide, titanium oxide-based baked pigment, ultramarine, cobalt aluminate and carbon black; azo-based compounds, quinacridone-based compounds, anthraquinone-based compounds, and perylene-based compounds. Organic pigments such as compounds, isoindolinone compounds, phthalocyanine compounds, quinophthalone compounds, sulene compounds and diketopyrrolopyrrole compounds; extender pigments such as barium sulfate and calcium carbonate; basic dyes, acid dyes and mordant dyes And the like.

The layer having the function of adjusting the refractive index (refractive index adjusting layer) as the functional layer 50 is a layer having a different refractive index from the resin film 40 and capable of giving a predetermined refractive index to the laminate. .
The refractive index adjusting layer may be, for example, a resin layer appropriately selected, a resin layer further containing a pigment in some cases, or a metal thin film.

  Examples of the pigment for adjusting the refractive index include silicon oxide, aluminum oxide, antimony oxide, tin oxide, titanium oxide, zirconium oxide, and tantalum oxide. The average particle size of the pigment is preferably 0.1 μm or less. When the average particle size of the pigment is 0.1 μm or less, irregular reflection of light passing through the refractive index adjusting layer can be prevented, and a decrease in transparency can be prevented.

  Examples of the metal used for the refractive index adjustment layer include metals such as titanium oxide, tantalum oxide, zirconium oxide, zinc oxide, tin oxide, silicon oxide, indium oxide, titanium oxynitride, titanium nitride, silicon oxynitride, and silicon nitride. Oxides or metal nitrides are exemplified.

  The functional layer 50 has the above functions as appropriate according to the use of the front plate (4). The functional layer 50 may be a single layer or a plurality of layers. Each layer may have one function or two or more functions.

  The functional layer 50 preferably has a function of expressing high hardness on the surface and a function of absorbing ultraviolet light. In this case, the functional layer 50 is “a single layer having a function of expressing high hardness on the surface and having a function of absorbing ultraviolet light”, and “a multilayer including a layer having a function of expressing high hardness on the surface and having a function of absorbing ultraviolet light”. Alternatively, it is preferable to include a “multilayer including a single layer having a function of expressing high hardness on the surface and a function of absorbing ultraviolet light and a layer having high hardness”.

  The thickness of the functional layer 50 is appropriately adjusted according to the flexible device to which the front plate (4) is applied, but is preferably 1 μm to 100 μm, more preferably 1 μm to 80 μm. Furthermore, it is preferably 1 μm to 30 μm, more preferably 1 μm to 20 μm. The functional layer 50 is typically thinner than the resin film 40.

  The front plate (4) can be obtained by forming the functional layer 50 on the main surface 40a of the resin film 40. The functional layer 50 can be formed by a known roll-to-roll or batch method.

  The ultraviolet absorbing layer as the functional layer 50 is formed, for example, by applying a dispersion liquid containing an ultraviolet absorber and a main material such as a resin in which the ultraviolet absorber is dispersed on the main surface 40a of the resin film 10 to form a coating film. It can be formed by forming and drying and curing the coating film.

  The hard coat layer as the functional layer 50 is formed, for example, by applying a solution containing a resin forming the hard coat layer to the main surface 40a of the resin film 40 to form a coating film, and drying and curing the coating film. Can be formed.

  The hue adjustment layer as the functional layer 50 is formed, for example, by applying a dispersion containing a pigment or the like forming the hue adjustment layer and a main material such as a resin in which the pigment or the like is dispersed on the main surface 40 a of the resin film 40. To form a coating film and drying and curing the coating film.

  The refractive index adjustment layer serving as the functional layer 50 includes, for example, a dispersion including, on the main surface 40 a of the resin film 40, inorganic particles forming the refractive index adjustment layer and a main material such as a resin in which the inorganic particles are dispersed. It can be formed by applying a liquid to form a coating film, and drying and curing the coating film.

  As the functional layer 50, a single layer having a function of expressing high hardness on the surface and a function of absorbing ultraviolet light is formed on the main surface 40 a of the resin film 40 by using an ultraviolet absorber and a resin such as a resin in which the ultraviolet absorber is dispersed. It can be formed by applying a dispersion containing a material and a resin for forming a hard coat layer to form a coating film, and then drying and curing the coating film. The resin as the main material and the resin forming the hard coat layer may be the same.

A multilayer functional layer including a layer exhibiting high hardness on the surface and a layer having a function of absorbing ultraviolet light can be formed by the following method.
On the main surface 40a of the resin film 40, a dispersion liquid containing an ultraviolet absorber and a main material such as a resin in which the ultraviolet absorber is dispersed is applied to form a coating film, and the coating film is dried and cured. To form an ultraviolet absorbing layer. Next, a solution containing a resin for forming the hard coat layer may be applied to the ultraviolet absorbing layer to form a coating film, and the hard coating layer may be formed by drying and curing the coating film. By this method, a multilayer functional layer including a layer having a function of expressing high hardness on the surface and a layer having a function of absorbing ultraviolet light is formed.

A multilayer functional layer including a single layer having a function of exhibiting high hardness on the surface and a function of absorbing ultraviolet light and a layer exhibiting high hardness can be formed by the following method.
On the main surface 40a of the resin film 40, a dispersion liquid containing an ultraviolet absorber, a main material such as a resin in which the ultraviolet absorber is dispersed, and a resin forming a hard coat layer is applied to form a coating film, The coating film is dried and cured to form a single layer having a function of expressing high hardness and a function of absorbing ultraviolet light on the surface, and a solution containing a resin for forming a hard coat layer is further formed on the single layer. A hard coat layer may be formed by applying a coating film to form a coating film and drying and curing the coating film. According to this method, a multilayer functional layer including a layer having a function of expressing high hardness on the surface and a function of absorbing ultraviolet light and a layer having a function of expressing high hardness on the surface is formed.

  The front plate (4) of the present embodiment obtained in this way has excellent flexibility, such as transparency and ultraviolet resistance required when applied to the front plate, and functions such as a function of expressing high hardness on the surface. Property. When Si / N on the main surface 40a of the resin film 40 is 8 or more, the front plate (4) also has excellent adhesion between the resin film 40 and the functional layer 50. Further, when the functional layer 50 is a layer having a function of expressing high hardness on the surface (hard coat layer), the functional layer 50 can have high surface hardness.

  FIG. 5 is also a cross-sectional view showing one embodiment of the front plate. The front plate (4) shown in FIG. 5 further includes a primer layer 45 provided between the resin film 40 and the functional layer 40, in addition to the resin film 40 and the functional layer 50 similar to the front plate of FIG. doing. The primer layer 45 is laminated on one main surface 40 a of the resin film 40. The functional layer 50 is laminated on the main surface 45 a of the primer layer 45 opposite to the main surface in contact with the resin film 40.

  The primer layer 45 is a layer formed from a primer agent, and preferably contains a material capable of increasing the adhesiveness between the resin film 40 and the functional layer 50. The compound contained in the primer layer 45 may be chemically bonded to the polyimide polymer or silicon material contained in the resin film 40 at the interface.

  Examples of the primer include a UV-curable, thermosetting, or two-component curable epoxy compound primer. The primer may be a polyamic acid. These primers are suitable for increasing the adhesion between the resin film 40 and the functional layer 50.

  The primer agent may include a silane coupling agent. The silane coupling agent may be chemically bonded to the silicon material contained in the resin film 40 by a condensation reaction. The silane coupling agent can be suitably used especially when the mixing ratio of the silicon material contained in the resin film 40 is high.

  Examples of the silane coupling agent include compounds having an alkoxysilyl group having a silicon atom and 1 to 3 alkoxy groups covalently bonded to the silicon atom. A compound having a structure in which two or more alkoxy groups are covalently bonded to a silicon atom is preferable, and a compound having a structure in which three alkoxy groups are covalently bonded to a silicon atom is more preferable. Examples of the alkoxy group include a methoxy group, an ethoxy group, an isopropoxy group, an n-butoxy group and a t-butoxy group. Among them, a methoxy group and an ethoxy group are preferable because they can enhance the reactivity with the silicon material.

  The silane coupling agent preferably has a substituent having a high affinity for the resin film 40 and the functional layer 50. From the viewpoint of affinity with the polyimide polymer contained in the resin film 40, the substituent of the silane coupling agent is preferably an epoxy group, an amino group, a ureide group, or an isocyanate group. When the functional layer 50 contains (meth) acrylates, if the silane coupling agent used for the primer layer 45 has an epoxy group, a methacryl group, an acrylic group, an amino group, or a styryl group, the affinity increases. preferable. Among these, a silane coupling agent having a substituent selected from a methacryl group, an acryl group, and an amino group is preferable because it tends to exhibit excellent affinity with the resin film 40 and the functional layer 50.

  The thickness of the primer layer 45 is appropriately adjusted according to the function layer 50, and is preferably 0.01 nm to 20 μm. When an epoxy-based primer is used, the thickness of the primer layer 45 is preferably 0.01 μm to 20 μm, and more preferably 0.1 μm to 10 μm. When a silane coupling agent is used, the thickness of the primer layer 45 is preferably 0.1 nm to 1 μm, and more preferably 0.5 nm to 0.1 μm.

  The front plate (4) in FIG. 5 is formed, for example, by applying a solution in which a primer is dissolved on the main surface 40a of the resin film 40 to form a coating film, and drying and curing the formed coating film to form a primer layer. Can be produced by a method including forming The other members are formed in the same manner as the front plate (4) in FIG. The primer layer 45 may be cured simultaneously with the functional layer 50, or may be separately cured before forming the functional layer 50.

  The front plate has high transparency and can maintain excellent visibility at the time of bending. The front plate can also have excellent flexibility. Further, when a primer layer is provided between the resin film and the functional layer, the adhesion between the resin film and the functional layer is increased. The front plate can have functionalities such as transparency, ultraviolet light resistance, and surface hardness required when applied to a base material of an optical member or a display member of a flexible device, or a front plate.

  The configuration of the front plate can be appropriately modified. For example, like the front plate (4) of FIG. 6, functional layers can be provided on both sides of the resin film. In this case, a primer layer may be provided between each functional layer and the resin film.

<Retardation film>
The polarizing plate can include a retardation film on the side of the polarizer opposite to the front plate side. As shown in FIG. 2, the polarizing plate may include a retardation film (5) on the side opposite to the polarizer side of the diffusion preventing layer (B). When the polarizing plate includes an adhesive layer, the polarizing plate may include a retardation film on the side of the adhesive layer opposite to the side of the diffusion preventing layer. The polarizing plate may include both a front plate and a retardation film. The above-mentioned polarizing plate with a front plate may have a retardation film on the side opposite to the polarizer side of the diffusion prevention layer.

The retardation film has a birefringence index Δn (λ) with respect to light having a wavelength of λ nm, which shows retardation represented by the following formulas (1-1), (2-1) and (3). It is preferable to include a retardation plate.
Δn (450) / Δn (550) ≦ 1.00 (1-1)
1.00 ≦ Δn (650) / Δn (550) (2-1)
120 nm ≦ Re (550) ≦ 180 nm (3)

  Δn (450), Δn (550), and Δn (650) represent birefringence at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.

The birefringence Δn (λ) is obtained by measuring the in-plane retardation and dividing by the thickness of the retardation film. Although a specific measuring method is shown in Examples, at this time, by measuring a film formed on a substrate such that the substrate itself has no retardation such as a glass substrate, a substantial retardation film is obtained. Can be measured. That is, the retardation film is preferably a retardation film having retardation represented by the following formulas (1) and (2) and the above formula (3).
Re (450) / Re (550) ≦ 1.00 (1)
1.00 ≦ Re (650) / Re (550) (2)

Re (450), Re (550), and Re (650) represent in-plane retardations at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.
The retardation film may be a single layer or a multilayer film. When the retardation film is a multilayer film, each film can be laminated with the above-mentioned pressure-sensitive adhesive or the following adhesive. In addition, each film can also be directly formed by a method such as applying a composition for forming each film.

[adhesive]
Adhesives include water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent volatile adhesives, moisture-curable adhesives, heat-curable adhesives, anaerobic-curable adhesives, and active energy ray-curable adhesives. General-purpose adhesives such as adhesives, hardener-mixed adhesives, hot-melt adhesives, pressure-sensitive adhesives (adhesives), and rewetting adhesives can be used. Among them, aqueous solvent volatile adhesives, active energy ray-curable adhesives, and pressure-sensitive adhesives are often used. The thickness of the adhesive layer can be appropriately adjusted according to the required adhesive strength and the like, and is 0.01 μm to 500 μm, preferably 0.1 μm to 300 μm. Although present, the thickness types may be the same or different.

  As the water-based solvent-evaporating adhesive, a water-soluble polymer such as a polyvinyl alcohol-based polymer or a starch, a polymer in an aqueous dispersion state such as an ethylene-vinyl acetate-based emulsion or a styrene-butadiene-based emulsion can be used as a main polymer. In addition to water and the main polymer, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent, and the like may be blended. In the case of bonding with the aqueous solvent volatilizing adhesive, the adhesive can be imparted by injecting the aqueous solvent volatilizing adhesive between the layers to be bonded, bonding the layer to be bonded, and then drying. The thickness of the adhesive layer when using the water-based solvent-evaporating adhesive may be 0.01 to 10 μm, preferably 0.1 to 1 μm. When the water-based solvent-evaporating adhesive is used in a plurality of layers, the thicknesses of the respective layers may be the same or different.

  The active energy ray-curable adhesive can be formed by curing an active energy ray-curable composition containing a reactive material that forms an adhesive layer upon irradiation with an active energy ray. The active energy ray-curable composition can contain at least one polymer of the same radical polymerizable compound and cationic polymerizable compound as the hard coat composition. The radical polymerizable compound is the same as the hard coat composition, and the same kind as the hard coat composition can be used. As the radically polymerizable compound used for the adhesive layer, a compound having an acryloyl group is preferable. It is also preferable to include a monofunctional compound in order to reduce the viscosity of the adhesive composition.

  The cationic polymerizable compound is the same as the hard coat composition, and the same kind as the hard coat composition can be used. As the cationically polymerizable compound used in the active energy ray-curable composition, an epoxy compound is particularly preferred. It is also preferable to include a monofunctional compound as a reactive diluent in order to reduce the viscosity of the adhesive composition.

  The active energy ray composition may further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cationic polymerization initiator, a radical and cationic polymerization initiator, and the like can be appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate radicals or cations, thereby promoting radical polymerization and cationic polymerization. In the description of the hard coat composition, an initiator capable of initiating at least one of radical polymerization and cationic polymerization by irradiation with active energy rays can be used.

  The active energy ray-curable composition further comprises an ion scavenger, an antioxidant, a chain transfer agent, an adhesion promoter, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, a defoamer solvent, an additive, and a solvent. Can be included. In the case of bonding with the active energy ray-curable adhesive, the active energy ray-curable composition is applied to one or both of the layers to be bonded and then bonded, and activated through either one of the bonding layers or both of the bonding layers. Bonding can be performed by curing by irradiating with energy rays. When the active energy ray-curable adhesive is used, the thickness of the adhesive layer may be 0.01 to 20 μm, preferably 0.1 to 10 μm. When the active energy ray-curable adhesive is used in a plurality of layers, the thickness of each layer may be the same or different.

The pressure-sensitive adhesive is classified into an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive and the like depending on the main polymer, and any of them can be used. The adhesive may contain a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, and the like, in addition to the base polymer. The components constituting the pressure-sensitive adhesive are dissolved and dispersed in a solvent to obtain a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition is dried after being coated on a substrate, thereby forming a pressure-sensitive adhesive layer adhesive layer. You. The pressure-sensitive adhesive layer may be directly formed, or a layer separately formed on a substrate may be transferred. It is also preferable to use a release film to cover the adhesive surface before bonding. When the active energy ray-curable adhesive is used, the thickness of the adhesive layer may be 0.1 to 500 μm, preferably 1 to 300 μm. When a plurality of layers of the pressure-sensitive adhesive are used, the thickness types of the respective layers may be the same or different.

  Further, the retardation film preferably includes the λ / 4 retardation plate described above. The λ / 4 retardation film is a film that gives a λ / 4 phase difference in a direction (in-plane direction of the film) orthogonal to the traveling direction of the incident light. It is preferable that the polarizer and the retardation film are arranged such that the angle between the absorption axis of the polarizer and the slow axis of the λ / 4 retardation plate is 45 ° ± 10 °. With such an axis angle, the polarizing plate can function as a circular polarizing plate.

  The λ / 4 retardation plate may be a stretched retardation plate manufactured by stretching a polymer film such as a cellulose film, an olefin film, and a polycarbonate film. If necessary, retarder, plasticizer, ultraviolet absorber, infrared absorber, colorant such as pigment or dye, optical brightener, dispersant, heat stabilizer, light stabilizer, antistatic agent, antioxidant , A lubricant, a solvent, and the like. The thickness of the stretch type retardation plate may be 200 μm or less, and preferably 1 μm to 100 μm. If the thickness exceeds 200 μm, the flexibility may be reduced.

  Further, another example of the λ / 4 retardation plate may be a liquid crystal application type retardation plate formed by applying a liquid crystal composition. The liquid crystal composition includes a liquid crystal compound having a property of exhibiting a liquid crystal state such as nematic, cholesteric, smectic, and the like. Any compound including a liquid crystal compound in the liquid crystal composition has a polymerizable functional group. The liquid crystal-coated retardation plate may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The liquid crystal coating type retardation plate can be manufactured by applying and curing a liquid crystal composition on an alignment film and forming a liquid crystal retardation layer in the same manner as described for the liquid crystal polarizing layer. The liquid crystal coating type retarder can be formed to be thinner than the stretch type retarder. The thickness of the liquid crystal coating type retardation plate may be 0.5 to 10 μm, preferably 1 to 5 μm. The liquid crystal-coated retardation plate can be peeled off from the substrate and transferred to be laminated, or the substrate can be laminated as it is. It is also preferable that the base material plays a role as a transparent base material for a protective film, a retardation plate, and a front plate.

  In general, there are many materials exhibiting a large birefringence at a short wavelength and a small birefringence at a long wavelength. In this case, since a phase difference of λ / 4 cannot be achieved in the entire visible light region, an in-plane phase difference of 100 to 180 nm, such that the phase difference value becomes λ / 4 near 560 nm, which has high visibility, is preferable. Is often designed to be 130 to 150 nm. It is preferable to use an inverse dispersion λ / 4 retardation plate using a material having a birefringence wavelength dispersion characteristic opposite to that of a normal one because visibility can be improved. As such a material, it is also preferable to use a material described in JP-A-2007-232873 or the like in the case of a stretch type retardation plate, or a material described in JP-A-2010-30979 in the case of a liquid crystal coating type retardation plate. .

  As another method, a technique of obtaining a broadband λ / 4 phase difference plate by combining with a λ / 2 phase difference plate is also known (Japanese Patent Application Laid-Open No. 10-90521). The λ / 2 retardation plate is also manufactured by the same material method as the λ / 4 retardation plate. The combination of the stretching type retardation plate and the liquid crystal coating type retardation plate is arbitrary, but it is preferable to use the liquid crystal coating type retardation plate because both can reduce the film thickness.

  There is also known a method of laminating a positive C plate on a polarizing plate in order to enhance visibility in an oblique direction (Japanese Patent Application Laid-Open No. 2014-224837). The positive C plate may also be a liquid crystal coating type retardation plate or a stretch type retardation plate. The retardation in the thickness direction is -200 to -20 nm, preferably -140 to -40 nm.

[Touch sensor]
The touch sensor can be arranged at a position suitable for maintaining the optical characteristics and the function of the touch panel, such as between the front plate and the polarizing plate or on the opposite side of the retardation film from the polarizing plate.
From the viewpoint of suppressing the reflected light from the touch sensor electrode, the touch sensor is preferably disposed on the side opposite to the polarizing plate side of the retardation film, but is not limited thereto. The polarizing plate with a front plate may include a touch sensor (6) on the opposite side of the retardation film (5) from the polarizing plate, as shown in FIG. Further, the retardation film and the touch sensor can be laminated via an adhesive layer.

  The touch sensor is used as an input unit. Various types of touch sensors have been proposed, such as a resistive film type, a surface acoustic wave type, an infrared type, an electromagnetic induction type, and a capacitance type, and any type may be used. Among them, the capacitance type is preferable. The capacitive touch sensor is divided into an active area and a non-active area located outside the active area. The active area is an area corresponding to an area (display unit) where a screen is displayed on the display panel, and is an area where a user's touch is sensed, and the inactive area is an area where the screen is not displayed on the display device (non-display area). Display area). The touch sensor has a flexible substrate; a sensing pattern formed on an active region of the substrate; a touch pattern formed on an inactive region of the substrate, and is connected to an external driving circuit through the sensing pattern and a pad unit. For each sensing line. The same material as the resin film of the front plate can be used as the substrate having flexible characteristics. The substrate of the touch sensor preferably has a toughness of 2,000 MPa% or more from the viewpoint of suppressing cracks in the touch sensor. More preferably, the toughness may be from 2,000 MPa to 30,000 MPa%.

  The sensing pattern may include a first pattern formed in a first direction and a second pattern formed in a second direction. The first pattern and the second pattern are arranged in different directions. The first pattern and the second pattern are formed on the same layer, and must be electrically connected to each other in order to detect a touched point. The first pattern is a form in which each unit pattern is connected to each other via a joint, whereas the second pattern is a structure in which each unit pattern is separated from each other in an island form. A separate bridge electrode is required for connection. As the sensing pattern, a known transparent electrode material can be applied. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), PEDOT (poly (3,4- (Ethylenedioxythiophene)), carbon nanotube (CNT), graphene, metal wire, and the like, and these can be used alone or in combination of two or more. Preferably, ITO can be used. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, terenium, and chromium. These can be used alone or in combination of two or more.

The bridge electrode may be formed on the insulating layer above the sensing pattern via an insulating layer. The bridge electrode may be formed on the substrate, and the insulating layer and the sensing pattern may be formed thereon. The bridge electrode may be formed of the same material as the sensing pattern, and may be formed of a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of these. You can also. Since the first and second patterns must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the joint of the first pattern and the bridge electrode, or may be formed in a layer structure covering the sensing pattern. In the latter case, the bridge electrode can connect the second pattern through a contact hole formed in the insulating layer. The touch sensor has a difference in transmittance between a pattern region in which a pattern is formed and a non-pattern region in which no pattern is formed, specifically, a light transmittance induced by a difference in refractive index in these regions. As a means for appropriately compensating for the difference, an optical adjustment layer may be further included between the substrate and the electrode, and the optical adjustment layer may include an inorganic insulating material or an organic insulating material. The optical control layer can be formed by coating a photocurable composition containing a photocurable organic binder and a solvent on a substrate. The photocurable composition may further include inorganic particles. The refractive index of the optical control layer can be increased by the inorganic particles.
The photocurable organic binder may include, for example, a copolymer of monomers such as an acrylate monomer, a styrene monomer, and a carboxylic acid monomer. The photocurable organic binder may be, for example, a copolymer containing different repeating units such as an epoxy group-containing repeating unit, an acrylate repeating unit, and a carboxylic acid repeating unit.
The inorganic particles may include, for example, zirconia particles, titania particles, alumina particles, and the like. The photocurable composition may further include additives such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

The polarizing plate with a front plate can be used for various display devices. A display device is a device having a display element, and includes a light-emitting element or a light-emitting device as a light-emitting source. Examples of the display device include a liquid crystal display device, an organic electroluminescence (EL) display device, an inorganic electroluminescence (EL) display device, a touch panel display device, an electron emission display device (for example, a field emission display device (FED), a surface field emission display device). (SED)), electronic paper (display device using electronic ink or electrophoretic element, plasma display device, projection display device (eg, grating light valve (GLV) display device, display device having digital micromirror device (DMD)) ) And a piezoelectric ceramic display etc. The liquid crystal display device includes any of a transmission type liquid crystal display device, a transflective type liquid crystal display device, a reflection type liquid crystal display device, a direct-view type liquid crystal display device, and a projection type liquid crystal display device. These display devices include a display device for displaying a two-dimensional image. It may be, or may be a stereoscopic display apparatus for displaying a three-dimensional image.
In particular, a polarizing plate with a front plate and an elliptically polarizing plate can be effectively used for a liquid crystal display device and an organic electroluminescence (EL) display device.

[Flexible image display device]
Further, the polarizing plate with the front plate can be preferably used as a laminate for a flexible image display device because of its excellent flexibility. The flexible image display device can be exemplified by a device including a laminate for a flexible image display device and an organic EL display panel. In the case of an organic EL display device, a laminate for a flexible image display device is arranged on the viewing side with respect to the organic EL display panel, and is configured to be bendable. The laminate for a flexible image display device may include a light-shielding pattern formed on at least one surface of any one of the front plate, the polarizing plate, and the touch sensor.

(Shading pattern)
The light-shielding pattern can be applied as at least a part of a bezel or a housing of the flexible image display device. The visibility of the image is improved by concealing the wiring arranged on the peripheral portion of the flexible image display device by the light-shielding pattern so that the wiring is difficult to see. The light-shielding pattern may be in the form of a single layer or multiple layers. The color of the light-shielding pattern is not particularly limited, and has various colors such as black, white, and metal. The light-shielding pattern can be formed of a pigment for realizing a color and a polymer such as an acrylic resin, an ester resin, an epoxy resin, polyurethane, or silicone. These can be used alone or in a mixture of two or more. The light-shielding pattern can be formed by various methods such as printing, lithography, and inkjet. The thickness of the light shielding pattern may be 1 μm to 100 μm, preferably 2 μm to 50 μm. It is also preferable to provide a shape such as inclination in the thickness direction of the optical pattern.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. In Examples, "parts" represents "parts by mass" unless otherwise specified. The evaluation method is as follows.
(1) Flexibility test A polyethylene terephthalate (PET) film was bonded to the polarizing plate with a front plate obtained in each of Examples and Comparative Examples via an adhesive layer 1, and a polarizing plate with a front plate / adhesive was attached. A laminate comprising the layer 1 / PET film was obtained. The PET film simulated a display element, and had a thickness of 100 μm.

  FIG. 7 is a diagram schematically illustrating a method of the flexibility test. A bending device (STS-VRT-500, manufactured by Science Town) having two stages 501 and 502 was prepared, and the stacked body 100 was mounted on the stages 501 and 502 (FIG. 7A). The distance (gap) C between the two stages 501 and 502 was set to 3 mm (1.5R). The stages 501 and 502 can swing about a gap (gap) C between the two stages. Initially, the two stages 501 and 502 constitute the same plane. The two stages 501 and 502 are rotated upward by 90 degrees with the position P1 and the position P2 as the centers of the rotation axes, the two stages 501 and 502 are closed (FIG. 7B), and the operation of opening the stages 501 and 502 again is performed once. Defined as bending. This operation was repeated, and the number of times of bending until the first crack occurred in the laminate 100 was counted.

The evaluation criteria are as follows.
◎ (very good): 200,000 times or more 〇 (good): 100,000 to less than 200,000 times △ (usable): 50,000 to less than 100,000 times x (somewhat inferior): 10,000 to 50,000 times Less than XX (poor): less than 10,000 times

  The flexibility test for the resin film constituting the front plate was performed by setting the distance (gap) C between the two stages 501 and 502 in FIG. 7 to 3 mm (1.5R). It was evaluated whether the number of times of bending the resin film until the resin film was broken exceeded 100,000 times.

(2) Tensile modulus The tensile modulus was measured using UTM (Universal Testing Machine, Autograph AG-X, Shimadzu Corporation) in accordance with JIS K7161. The stretching conditions were as follows: room temperature (temperature 23 ° C.), speed 1.5 mm / min, width 40 mm, gauge length 50 mm.

(3) Heat resistance test The polarizing plates produced in each of the examples and comparative examples were bonded to glass via the pressure-sensitive adhesive layer 2 to obtain a laminate composed of polarizing plate / pressure-sensitive adhesive layer 2 / glass. The luminosity correction polarization degree of this laminate was measured in a visible light region using a spectrophotometer (V7100, manufactured by JASCO Corporation), and the luminosity correction polarization degree [%] before the heat resistance test was obtained. Next, the laminate was allowed to stand in an oven at a temperature of 85 ° C. for 500 hours, and then the degree of luminosity correction polarization was measured in the same manner as the luminosity correction polarization degree [%] after the heat resistance test. Based on the obtained degree of visibility correction polarization, the absolute value (| ΔP |) [%] of the amount of change in the degree of visibility correction polarization before and after the heat resistance test was calculated.

The evaluation criteria are as follows.
◎ (very good): less than 3% 〇 (good): 3% or more and less than 5% △ (usable): 5% or more and less than 7% （(somewhat inferior): 7% or more and less than 10% XX (poor): 10% or more

(4) Yellowness The yellowness of the resin film was measured by an ultraviolet-visible-near-infrared spectrophotometer V-670 manufactured by JASCO Corporation in accordance with JIS K7373: 2006. After the background measurement was performed without the resin film, the resin film was set on a sample holder, and the transmittance of light having a wavelength of 300 to 800 nm was measured to determine the tristimulus values (X, Y, Z). . YI was calculated based on the following equation.
YI = 100 × (1.2767X−1.0592Z) / Y

(5) Storage elastic modulus The storage elastic modulus at a temperature of 25 ° C was measured using a viscoelasticity measuring device (MCR-301, Anton Paar). The same pressure-sensitive adhesive sheet as used in Examples and Comparative Examples was made 30 mm in width x 30 mm in length, the release film was peeled off, and a plurality of sheets were laminated so as to have a thickness of 150 μm, bonded to a glass plate, and then bonded to a measurement chip. In the temperature range of -20 ° C to 100 ° C, the measurement was performed under the conditions of a frequency of 1.0 Hz, an amount of deformation of 1%, and a heating rate of 5 ° C / min. confirmed.

The following materials were prepared.
(1) Front plate (1-1) Front plate 1:
A film comprising a resin film made of a polyimide-based polymer and a hard coat layer formed on one main surface thereof. The thickness of the resin film was 50 μm, and the thickness of the hard coat layer was 10 μm. The number of bendings before the resin film was broken exceeded 100,000. The yellowness of the resin film was 1.2.

(1-2) Front plate 2:
A film comprising a resin film made of polyethylene terephthalate and a hard coat layer formed on one main surface thereof. The thickness of the resin film was 40 μm, and the thickness of the hard coat layer was 10 μm. The number of bendings before the resin film was broken exceeded 100,000. The yellowness of the resin film was 1.6.

(1-3) Front plate 3:
A film comprising a resin film made of triacetyl cellulose and a hard coat layer formed on one main surface thereof. The thickness of the resin film was 60 μm, and the thickness of the hard coat layer was 10 μm. The number of bendings before the resin film was broken was less than 100,000. The yellowness of the resin film was 0.6.

このポリマーを濃度５重量％で、シクロペンタノンに溶解した溶液を配向膜形成用組成物として用いた。 (2) Composition for forming an alignment film A polymer having a photoreactive group consisting of the following structural units was prepared.

A solution in which this polymer was dissolved in cyclopentanone at a concentration of 5% by weight was used as a composition for forming an alignment film.

(3) Polarizer-forming composition The compound (1-1) and the compound (1-2) represented by the following structures were used as a polymerizable liquid crystal compound. Compound (1-1) and compound (1-2) are described in Lub et al. Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996).

Compound (1-1)

Compound (1-2)

  Compound (2-1a), compound (2-1b) and compound (2-3a) represented by the following structures were used as dichroic dyes.

Compound (2-1a)

Compound (2-1b)

Compound (2-3a)

  The composition for forming a polarizer comprises 75 parts by weight of the compound (1-1), 25 parts by weight of the compound (1-2), and the above formulas (2-1a), (2-1b), and (2) as dichroic dyes. 2.5 parts by weight of each of the azo dyes represented by -3a), and 6 parts by weight of 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one (Irgacure 369, BASF) as a polymerization initiator And 1.2 parts by weight of a polyacrylate compound (BYK-361N, BYK) as a leveling agent were mixed with 400 parts by weight of toluene as a solvent, and the resulting mixture was stirred at 80 ° C. for 1 hour. did.

(4) λ / 4 retardation plate The following components were mixed, and the resulting mixture was stirred at 80 ° C for 1 hour to obtain a λ / 4 retardation plate-forming composition.

Compound represented by the following formula: 80 parts by weight

Compound represented by the following formula: 20 parts by weight

Polymerization initiator (Irgacure 369, BASF): 6 parts by weight Leveling agent (BYK-361N, polyacrylate compound, BYK): 0.1 parts by weight Solvent (cyclopentanone): 400 parts by weight

A PET film having a thickness of 100 μm was prepared as a substrate. The composition for forming an alignment film was applied onto a PET film by a bar coating method, and dried by heating in a drying oven at 80 ° C. for 1 minute. The obtained film was subjected to a polarized UV irradiation treatment to form an alignment film (AL2). The polarized UV treatment was performed using a UV irradiation apparatus (SPOT CURE SP-7, manufactured by Ushio Inc.) under the condition that the integrated light amount measured at a wavelength of 365 nm was 100 mJ / cm ² . The polarization direction of the polarized light UV was set to 45 ° with respect to the absorption axis of the polarizer.

The composition for forming a λ / 4 retardation plate was applied on the alignment film (AL2) by a bar coating method, heated and dried in a drying oven at 120 ° C. for 1 minute, and then cooled to room temperature. The obtained coating film was irradiated with ultraviolet light having an integrated light amount of 1000 mJ / cm ² (based on 365 nm) using the above-mentioned UV irradiation device, thereby forming a λ / 4 retardation plate. The thickness of the obtained λ / 4 retardation plate was 2.0 μm.

(5) Positive C plate The components shown below were mixed, and the resulting mixture was stirred at 80 ° C for 1 hour to obtain a positive C plate forming composition.

Compound represented by the following formula (LC242, manufactured by BASF): 100 parts by weight

Polymerization initiator (Irgacure 907, 2-methyl-4 '-(methylthio) -2-morpholinopropiophenone, BASF): 2.6 parts by weight Leveling agent (BYK-361N, polyacrylate compound, BYK): 0. 5 parts by weight Additive (LR9000, BASF): 5.7 parts by weight Solvent (propylene glycol 1-monomethyl ether 2-acetate): 412 parts by weight

  A PET film having a thickness of 100 μm was prepared as a substrate. The composition for forming an alignment film was applied on a PET film by a bar coating method, and dried by heating in a drying oven at 90 ° C. for 1 minute to obtain an alignment film (AL3).

The composition for forming a positive C plate was applied on the alignment film (AL3) by a bar coating method, and dried by heating in a drying oven at 90 ° C. for 1 minute. The obtained coating film was irradiated with ultraviolet light having an integrated light amount of 1000 mJ / cm ² (based on 365 nm) using the above-mentioned UV irradiation device under a nitrogen atmosphere, thereby forming a positive C plate. The thickness of the obtained positive C plate was 3.0 μm.

(6) Diffusion-preventing layer composition (6-1) Diffusion-preventing layer 1 composition The diffusion-preventing layer 1 composition is composed of 2.8 parts by mass of dendrimer acrylate having 18 functional acrylic groups (Miramer SP1106, Miwon). 6.6 parts by mass of a urethane acrylate having a functional acrylic group (Miramer PU-620D, Miwon), 0.5 parts by mass of a photopolymerization initiator (Irgacure-184, BASF), a leveling agent (BYK-3530, BYK) ) 0.1 part by mass and 90 parts by mass of methyl ethyl ketone (MEK).

(6-2) Diffusion prevention layer 2 composition Diffusion prevention layer 2 composition is 100 parts by weight of water, 3 parts by weight of polyvinyl alcohol resin powder (Kuraray Co., Ltd., average degree of polymerization 18000, trade name: KL-318), It was prepared by mixing 1.5 parts by weight of a polyamide epoxy resin (crosslinking agent, manufactured by Sumika Chemtex Co., Ltd., trade name: SR650 (30)).

(7) Adhesive layer (Polymerization Example 1)
In a reactor equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, 81.8 parts of acetone, 98.4 parts of butyl acrylate, 0.6 part of acrylic acid, and 2-hydroxyethyl acrylate 1.0 Of the mixed solution, and the internal temperature was raised to 55 ° C. while replacing the air in the apparatus with nitrogen gas to make it oxygen-free. Thereafter, a solution prepared by dissolving 0.14 part of azobisisobutyronitrile (polymerization initiator) in 10 parts of acetone was added in total. One hour after the addition of the polymerization initiator, acetone was continuously added to the reactor at an addition rate of 17.3 parts / hr so that the concentration of the acrylic resin excluding the monomer was 35%. The temperature was kept at -56 ° C for 12 hours, and finally, ethyl acetate was added to adjust the concentration of the acrylic resin to 20%. Thus, an acrylic resin solution was obtained.

(Polymerization Example 2)
Acrylic resin solution was prepared in the same manner as in Polymerization Example 1, except that the composition of the monomer was changed to 98.6 parts of butyl acrylate, 0.4 parts of acrylic acid, and 1.0 parts of 2-hydroxyethyl acrylate. I got

(Polymerization Example 3)
Polymerization Example 1 except that the monomer composition was changed to 78.0 parts of butyl acrylate, 20 parts of methyl methacrylate, 1.0 part of acrylic acid, and 1.0 part of 2-hydroxyethyl acrylate. An acrylic resin solution was obtained in the same manner.

(Polymerization Example 4)
Polymerization Example 1 except that the composition of the monomer was changed to 68.0 parts of butyl acrylate, 30 parts of methyl methacrylate, 1.0 part of acrylic acid, and 1.0 part of 2-hydroxyethyl acrylate. An acrylic resin solution was obtained in the same manner.

Next, a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet were produced using the above acrylic resin solution. In the following production examples, the following were used as the isocyanate compound and the silane compound.
Isocyanate-based compound: Coronate L, an ethyl acetate solution of a trimethylolpropane adduct of tolylene diisocyanate (solid concentration 75%), manufactured by Tosoh Corporation.
Silane-based compound: KBM-403, 3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.

(7-1) Adhesive layer 1
Acrylic resin obtained in Polymerization Example 1: 100 parts (nonvolatile content),
Coronate L: 0.5 part,
KBM-403: 0.5 part was mixed. Ethyl acetate was added so that the solid content concentration became 10% to obtain a pressure-sensitive adhesive composition.

  The obtained pressure-sensitive adhesive composition was applied to a release-treated surface of a release-treated polyethylene terephthalate film (thickness: 38 μm) using an applicator so that the thickness after drying was 25 μm. The coating layer was dried at 100 ° C. for 1 minute to obtain a film having the pressure-sensitive adhesive layer 1. Thereafter, another release-treated polyethylene terephthalate film (thickness: 38 μm) was bonded onto the pressure-sensitive adhesive layer. Then, it was cured for 7 days at a temperature of 23 ° C. and a relative humidity of 50% RH.

(7-2) Adhesive layer 2
Acrylic resin obtained in Polymerization Example 2: 100 parts (nonvolatile content),
Coronate L: 0.4 part,
KBM-403: 0.5 part was mixed. Ethyl acetate was added so that the solid content concentration became 10% to obtain a pressure-sensitive adhesive composition. From the obtained pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer 2 having a thickness of 25 μm was produced in the same manner as in the preparation of the pressure-sensitive adhesive layer 1.

(7-3) Adhesive layer 3
Acrylic resin obtained in Polymerization Example 3: 100 parts (nonvolatile content),
Coronate L: 3.0 parts,
KBM-403: 0.5 part was mixed. Ethyl acetate was added so that the solid content concentration became 10% to obtain a pressure-sensitive adhesive composition. From the obtained pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer 3 having a thickness of 25 μm was produced in the same manner as in the preparation of the pressure-sensitive adhesive layer 1.

(7-4) Adhesive layer 4
The pressure-sensitive adhesive layer 4 was produced in the same manner as in the production of the pressure-sensitive adhesive layer 3, except that the coating was performed so that the thickness after drying was 5 μm.

(7-5) Adhesive layer 5
Acrylic resin obtained in Polymerization Example 4: 100 parts (nonvolatile content),
Coronate L: 3.0 parts,
KBM-403: 0.5 part was mixed. Ethyl acetate was added so that the solid content concentration became 10% to obtain a pressure-sensitive adhesive composition. From the obtained pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer 5 having a thickness of 25 μm was produced in the same manner as in the preparation of the pressure-sensitive adhesive layer 1.

(Example 1)
A PET film having a thickness of 100 μm was prepared as a substrate. The composition of the diffusion preventing layer 1 was applied on a PET film by a bar coating method, and dried by heating in a drying oven at 80 ° C. for 3 minutes. Using a UV irradiation apparatus (SPOT CURE SP-7, manufactured by Ushio Inc.), the obtained coating film was irradiated with UV light having an exposure amount of 500 mJ / cm ² (based on 365 nm) to form a diffusion prevention layer 1. . The thickness of the diffusion prevention layer 1 was measured by a laser microscope (OLS3000, manufactured by Olympus Corporation) and found to be 2.0 μm. Thus, a laminate comprising the diffusion preventing layer 1 / substrate (PET) was obtained.

(Preparation of polarizer)
Corona treatment was applied to the diffusion prevention layer 1 of the laminate composed of the diffusion prevention layer 1 / substrate (PET).
The conditions for the corona treatment were an output of 0.3 kW and a treatment speed of 3 m / min. Thereafter, the composition for forming an alignment film was applied on the diffusion preventing layer 1 by a bar coating method, and was dried by heating in a drying oven at 80 ° C. for 1 minute. The obtained coating was subjected to polarized UV irradiation treatment to form an alignment film (AL1). In the polarized UV treatment, light irradiated from a UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.) is transmitted through a wire grid (UIS-27132 ##, manufactured by Ushio Inc.) to have a wavelength of 365 nm. The measurement was carried out under the condition that the integrated light amount measured in step was 100 mJ / cm ² . The thickness of the alignment film (AL1) was 100 nm.

The composition for forming a polarizer was applied on the formed alignment film (AL1) by a bar coating method, heated and dried in a drying oven at 120 ° C. for 1 minute, and then cooled to room temperature. A polarizer was formed by irradiating the coating with ultraviolet rays using the above-mentioned UV irradiator so that the integrated light amount became 1200 mJ / cm ² (based on 365 nm). The thickness of the obtained polarizer was 1.8 μm.

  On the formed polarizer, the composition of the diffusion preventing layer 2 was applied by a bar coating method so that the thickness after drying became 1.0 μm, and dried at a temperature of 80 ° C. for 3 minutes. Thus, a polarizing plate composed of PET / diffusion prevention layer 1 / AL1 / polarizer / diffusion prevention layer 2 was obtained.

  The pressure-sensitive adhesive layer 4 was laminated on the diffusion preventing layer 2 of the polarizing plate. A λ / 4 retardation plate and a polarizing plate were laminated via the pressure-sensitive adhesive layer 4. The PET film as the base material was peeled off from the λ / 4 retardation plate, and the pressure-sensitive adhesive layer 4 was laminated on the exposed surface. A λ / 4 retardation plate and a positive C plate were laminated via the pressure-sensitive adhesive layer. The PET film as a substrate was peeled from the positive C plate.

  The pressure-sensitive adhesive layer 1 was laminated on the front plate 1. The PET film on the diffusion prevention layer 1 was peeled off from the polarizing plate, and the polarizing plate and the front plate 1 were laminated via the adhesive layer 1. When laminating each layer, the lamination surface was subjected to corona treatment. Thus, the front plate 1 / adhesive layer 1 / diffusion prevention layer 1 / AL1 / polarizer / diffusion prevention layer 2 / adhesive layer 4 / λ / 4 retardation plate / adhesive layer 4 / positive C plate Was produced.

(Example 2)
A polarizing plate was produced in the same manner as in Example 1.

  The pressure-sensitive adhesive layer 1 was laminated on the front plate 1. The diffusion preventing layer 2 of the polarizing plate and the front plate 1 were laminated via the pressure-sensitive adhesive layer 1. The PET film on the diffusion prevention layer 1 was peeled off, and the pressure-sensitive adhesive layer 4 was laminated on the exposed surface. A λ / 4 retardation plate and a polarizing plate were laminated via the pressure-sensitive adhesive layer 4. The PET film as the base material was peeled off from the λ / 4 retardation plate, and the pressure-sensitive adhesive layer 4 was laminated on the exposed surface. A λ / 4 retardation plate and a positive C plate were laminated via the pressure-sensitive adhesive layer. The PET film as a substrate was peeled from the positive C plate. Thus, the front plate 1 / adhesive layer 1 / diffusion prevention layer 2 / polarizer / AL1 / diffusion prevention layer 1 / adhesive layer 4 / λ / 4 retardation plate / adhesive layer 4 / positive C plate Was produced.

(Example 3)
A polarizing plate with a front plate was produced in the same manner as in Example 1 except that the thickness of the diffusion preventing layer 1 was changed to 15 μm. This polarizing plate with a front plate has a front plate 1 / adhesive layer 1 / diffusion prevention layer 1 / AL1 / polarizer / diffusion prevention layer 2 / adhesive layer 4 / λ / 4 retardation plate / adhesive layer 4 / positive Of the C plate.

(Example 4)
A polarizing plate with a front plate was produced in the same manner as in Example 1, except that the front plate 1 was changed to the front plate 2. This polarizing plate with a front plate has a front plate 2 / adhesive layer 1 / diffusion prevention layer 1 / AL1 / polarizer / diffusion prevention layer 2 / adhesive layer 4 / λ / 4 retardation plate / adhesive layer 4 / positive. Of the C plate.

(Example 5)
A polarizing plate with a front plate was produced in the same manner as in Example 1 except that the front plate 1 was changed to the front plate 3. This polarizing plate with a front plate has a front plate 3 / adhesive layer 1 / diffusion prevention layer 1 / AL1 / polarizer / diffusion prevention layer 2 / adhesive layer 4 / λ / 4 retardation plate / adhesive layer 4 / positive. Of the C plate.

(Example 6)
A polarizing plate with a front plate was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive layer 1 was changed to the pressure-sensitive adhesive layer 2. This polarizing plate with a front plate has a front plate 1 / adhesive layer 2 / diffusion prevention layer 1 / AL1 / polarizer / diffusion prevention layer 2 / adhesive layer 4 / λ / 4 retardation plate / adhesive layer 4 / positive Of the C plate.

(Example 7)
A polarizing plate with a front plate was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive layer 1 was changed to the pressure-sensitive adhesive layer 3. This polarizing plate with a front plate has a front plate 1 / adhesive layer 3 / diffusion prevention layer 1 / AL1 / polarizer / diffusion prevention layer 2 / adhesive layer 4 / λ / 4 retardation plate / adhesive layer 4 / positive Of the C plate.

(Comparative Example 1)
A polarizing plate with a front plate was produced in the same manner as in Example 1 except that the diffusion preventing layer 2 was not formed. This polarizing plate with a front plate has a structure of a front plate 1 / adhesive layer 1 / diffusion prevention layer 1 / AL1 / polarizer / adhesive layer 4 / λ / 4 retardation plate / adhesive layer 4 / positive C plate. Had.

(Comparative Example 2)
A polarizing plate with a front plate was produced in the same manner as in Example 2 except that the diffusion preventing layer 2 was not formed. This polarizing plate with a front plate has a structure of front plate 1 / adhesive layer 1 / polarizer / AL1 / diffusion prevention layer 1 / adhesive layer 4 / λ / 4 retardation plate / adhesive layer 4 / positive C plate. Had.

(Comparative Example 3)
A polarizing plate with a front plate was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive layer 1 was changed to the pressure-sensitive adhesive layer 5. This polarizing plate with a front plate has a front plate 1 / adhesive layer 5 / diffusion prevention layer 1 / AL1 / polarizer / diffusion prevention layer 2 / adhesive layer 4 / λ / 4 retardation plate / adhesive layer 4 / positive. Of the C plate.

  The above evaluation was performed on the polarizing plate with front plate manufactured in each of the examples and the comparative examples. The results are shown in the table below.

1: Polarizer 2: Diffusion prevention layer A
3: Diffusion prevention layer B
4: Front plate 5: Retardation film 6: Touch sensor 7: Adhesive layer 20: Polarizing plates 10 to 13: Polarizing plate with front plate

Claims (10)

A polarizing plate having a diffusion prevention layer A, a polarizer and a diffusion prevention layer B in this order,
And a front plate disposed on the side opposite to the polarizer side in the diffusion prevention layer A or the diffusion prevention layer B,
The front plate is laminated to the polarizing plate via an adhesive layer,
The thickness of the diffusion prevention layer A and the diffusion prevention layer B is 20 μm or less,
The thickness of the polarizer is 10 μm or less,
The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is a polarizing plate with a front plate, which has a storage elastic modulus at 25 ° C. of 0.6 MPa or less. The front plate is a laminated film including a resin film containing a polyimide-based polymer or a polyamide-based polymer, and a functional layer provided on at least one main surface side of the resin film, A polarizing plate with a front plate as described.   The polarizing plate with a front plate according to claim 2, wherein the functional layer is a layer having at least one function selected from the group consisting of ultraviolet absorption, surface hardness, hue adjustment, and refractive index adjustment. The resin film has a tensile modulus of 4.0 GPa or more;
In a bending test in which the resin film is repeatedly bent back into a U-shape until the distance between the resin films facing each other is 3 mm, the number of times the resin film is folded until the resin film breaks exceeds 100,000 times,
The polarizing plate with a front plate according to claim 2 or 3, wherein the degree of yellowness is 5 or less. The polarizing plate with a front plate according to any one of claims 1 to 4, wherein the polarizing plate includes a retardation film on a side of the polarizer opposite to the front plate. The polarizing plate with a front plate according to claim 5, wherein the retardation film is laminated on the diffusion preventing layer A or the diffusion preventing layer B via an adhesive layer. The polarizing plate with a front plate according to claim 5, wherein the retardation film includes a λ / 4 retardation plate. The polarizing plate with a front plate according to any one of claims 1 to 7, further comprising a touch sensor.   An organic EL display device comprising the polarizing plate with a front plate according to claim 1. A flexible image display device comprising the polarizing plate with a front plate according to claim 1.

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