阅读说明：本技术 光学层叠体 (Optical laminate ) 是由 祖父江彰二 神野彩乃 住吉铃鹿 于 2019-06-06 设计创作，主要内容包括：本发明的目的在于提供一种光学层叠体,其是具有偏振板和相位差膜的光学层叠体,该光学层叠体即使受到热冲击也能够抑制裂纹的产生。一种光学层叠体,其特征在于,其是具有偏振板和相位差膜的光学层叠体,上述相位差膜的穿刺弹性模量为50g/mm以下,所述穿刺弹性模量是使用对膜面垂直地挤压穿刺夹具的前端而产生断裂时的、从上述穿刺夹具的前端向上述相位差膜施加的应力F(g)和上述相位差膜的应变量S(mm)按照下述式(1)算出的。(1)穿刺弹性模量(g/mm)＝F(g)/S(mm)。(The invention aims to provide an optical laminate which is provided with a polarizing plate and a phase difference film and can inhibit the generation of cracks even if the optical laminate receives thermal shock. An optical laminate comprising a polarizing plate and a retardation film, wherein the retardation film has a puncture elastic modulus of 50g/mm or less, and the puncture elastic modulus is calculated by using a stress F (g) applied to the retardation film from the tip of a puncture jig when the film surface is vertically pressed against the tip of the puncture jig and the film breaks, and a strain amount S (mm) of the retardation film, according to the following formula (1). (1) Puncture elastic modulus (g/mm) ═ f (g)/s (mm).)

1. An optical laminate comprising a retardation film,

The retardation film has a puncture elastic modulus of 50g/mm or less, which is calculated by using a stress F applied to the retardation film from the tip of a puncture jig when the tip of the puncture jig is pressed perpendicularly to the film surface and the film breaks, and a strain amount S of the retardation film, according to the following formula (1),

Formula (1): the puncture elastic modulus is F/S,

Wherein the unit of the stress F is g, the unit of the strain quantity S is mm, and the unit of the puncture elastic modulus is g/mm.

2. The optical laminate according to claim 1, wherein the retardation film comprises a retardation layer obtained by curing a polymerizable liquid crystal compound.

3. The optical stack of claim 2, wherein the phase difference film further comprises an alignment layer.

4. The optical stack of claim 1, wherein the retardation layer has a vertical orientation.

5. The optical stack of claim 1, further comprising a polarizer.

6. the optical stack of claim 5, further comprising a front panel disposed on a viewing side of the polarizing plate.

7. The optical stack of claim 6, wherein the optical stack further comprises a contact sensor.

8. A display device, wherein the optical laminate according to any one of claims 1 to 7 is laminated on a display element.

Technical Field

The present invention relates to an optical laminate.

Background

In recent years, image display devices typified by organic electroluminescence (hereinafter also referred to as organic EL) display devices have rapidly spread. An organic EL display device is equipped with a circularly polarizing plate having a polarizing plate and a retardation film, or an optical laminate further laminated with other optical functional layers.

As a retardation film for an image display device such as an organic EL display device, a retardation film obtained by stretching a conventional resin film or a retardation film formed using a liquid crystal compound as a material has been studied, and as the demand for the reduction in thickness of the image display device has become stronger, the reduction in thickness has been required for the retardation film and an optical laminate including the retardation film (for example, see patent document 1).

Disclosure of Invention

Problems to be solved by the invention

Such an optical laminate having a retardation film may be cracked from the retardation film due to expansion and contraction caused by temperature change. In particular, when a rapid temperature change (thermal shock) is applied, cracks are likely to occur. When such cracks occur, not only the durability of the optical laminate is reduced, but also the visibility of the display device is reduced.

An object of the present invention is to solve the above problems and provide an optical laminate having a retardation film, which is capable of suppressing the occurrence of cracks even in an environment where a rapid temperature change (thermal shock) is applied.

Means for solving the problems

The present invention provides optical laminates as shown in the following [1] to [7 ].

[1] An optical laminate comprising a retardation film, wherein the retardation film has a puncture elastic modulus of 50g/mm or less, and the puncture elastic modulus is calculated by using a stress F (g) applied to the retardation film from a tip of a puncture jig when the tip of the puncture jig is pressed perpendicularly to a film surface and a strain S (mm) of the retardation film, the stress F (g) being generated when the tip of the puncture jig is broken, according to the following formula (1).

Formula (1): puncture modulus of elasticity (g/mm) ═ F (g)/S (mm)

[2] The optical laminate according to [1], wherein the retardation film comprises a retardation layer obtained by curing a polymerizable liquid crystal compound.

[3] The optical laminate according to [2], wherein the retardation film further comprises an alignment layer.

[4] The optical laminate according to [1], wherein the retardation layer has a vertical alignment property.

[5] The optical laminate according to [1], wherein the optical laminate further comprises a polarizing plate.

[6] The optical laminate according to [5], wherein the optical laminate further comprises a front panel, and the front panel is disposed on a viewing side of the polarizing plate.

[7] The optical layered body according to [6], wherein the optical layered body further comprises a touch sensor.

The present invention also provides a display device shown in [8] below.

[8] A display device, wherein the optical laminate according to any one of [1] to [7] is laminated on a display element.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there is provided an optical laminate having a retardation film, which is capable of suppressing the occurrence of cracks even in an environment in which a rapid temperature change occurs.

Drawings

Fig. 1 (a) to (c) are schematic cross-sectional views showing an example of the layer structure of the optical laminate of the present invention.

fig. 2 is a schematic cross-sectional view showing an example of the layer structure of the organic EL display device.

Fig. 3 is a schematic cross-sectional view showing a layer structure in a thermal shock test using the optical layered bodies produced in examples 1 to 6 and comparative examples 1 and 2.

Description of the reference numerals

1 first retardation film (retardation film)

2 second phase difference film

3 polarizing plate

4 organic EL display element

5 front panel

6 light-shielding pattern

10 phase difference layer

11 alignment layer

12 adhesive layer

13 adhesive layer

14 glass plate

100, 101, 102, 104 optical stack

103 organic EL display device

Detailed Description

(definitions of terms and symbols)

The definitions of the terms and symbols in the present specification are as follows.

(1) Modulus of elasticity for puncture

The puncture elastic modulus is a physical property value of the film defined by a stress f (g) applied to the film from the tip of the puncture jig when the tip of the puncture jig is pressed perpendicularly to the film surface and the film is broken, and a strain amount s (mm) of the film until the through-hole is formed or the film is broken. The puncture elastic modulus is expressed as a proportionality constant between stress F and strain S (stress F/strain S).

The puncture elastic modulus can be measured by a compression tester equipped with a load cell, and examples of the compression tester include a puncture tester "NDG 5" manufactured by katote corporation, a portable compression tester "KES-G5", a small bench tester "EZ Test" manufactured by shimadzu corporation, and the like. The stress applied to the film at the time of occurrence of fracture and the amount of strain generated up to that time can be measured from the stress-strain curve obtained using such a compression tester.

The rupture of the membrane at the time of pressing the puncture jig also includes a case where a through hole is formed in the membrane by the front end of the jig.

(2) Alignment layer

The alignment layer is a layer having the ability to restrict the direction of the molecular axis of the polymerizable liquid crystal compound forming the retardation layer so as to have desired retardation characteristics. A layer (retardation layer) obtained by curing the polymerizable liquid crystal compound is formed on the substrate with the alignment layer interposed therebetween. Examples of the alignment layer include an alignment layer containing an alignment polymer, a photo-alignment film, and a groove alignment layer in which a concave-convex pattern or a plurality of grooves are formed on the surface thereof and aligned.

(3) Vertical orientation

The vertical alignment property is a state in which the direction of the molecular axis of the polymerizable liquid crystal compound forming the retardation layer is substantially perpendicular to the lamination surface of each layer constituting the optical laminate. As a representative example of the retardation layer exhibiting vertical alignment, a positive C layer can be cited.

(4) Refractive index (nx, ny, nz)

"nx" is a refractive index in a direction in which the in-plane refractive index is maximized (i.e., the slow axis direction), "ny" is a refractive index in a direction orthogonal to the slow axis in the plane, and "nz" is a refractive index in the thickness direction.

(5) Phase difference value in plane

The in-plane phase difference (Re [ lambda ]) means the in-plane phase difference of the film at 23 ℃ and a wavelength [ lambda ] (nm). When the film thickness is d (nm), Re λ is determined as Re [ [ λ ] ═ (nx-ny) × d.

(6) Phase difference value in thickness direction

The in-plane retardation (Rth [ lambda ]) means a retardation in the thickness direction of the film at 23 ℃ over a long wavelength (nm). When the film thickness is d (nm), Rth [ λ ] is determined by Rth [ λ ] (nx + ny)/2-nz) × d.

< optical layered body >

The optical laminate of the present invention has a retardation film, and the puncture elastic modulus of the retardation film is 50g/mm or less. The retardation film has a retardation layer. The retardation layer preferably has a layer formed from a composition containing a polymerizable liquid crystal compound. Specifically, the layer formed from the composition containing the polymerizable liquid crystal compound refers to a layer obtained by curing the polymerizable liquid crystal compound. In the present specification, a layer to which a retardation of λ/2 is given, a layer to which a retardation of λ/4 is given (positive a layer), a positive C layer, and the like may be collectively referred to as a retardation layer. Further, the retardation film may contain an alignment layer described later.

An example of the layer structure of the optical laminate of the present invention will be described below with reference to fig. 1. The optical laminate 100 shown in fig. 1 (a) has a layer structure in which the retardation layer 10 is laminated on one surface of the alignment layer 11, and the pressure-sensitive adhesive layer 12 is provided on the other surface of the alignment layer 11. The pressure-sensitive adhesive layer 12 may be a pressure-sensitive adhesive layer for bonding to an organic EL display element or the like. In the optical laminate 100, the retardation film 1 is composed of a retardation layer 10 and an alignment layer 11.

The optical laminate 101 shown in fig. 1 (b) has a layer structure in which the second phase difference film 2 is laminated on the surface of the retardation layer 10 opposite to the surface on which the alignment layer 11 is laminated in fig. 1 (a) via the adhesive layer 13. The pressure-sensitive adhesive layer 12 may be a pressure-sensitive adhesive layer for bonding to an organic EL display element or the like, as in fig. 1 (a). In the optical laminate 101, the first retardation film 1 is composed of a retardation layer 10 and an alignment layer 11.

The optical laminate 102 shown in fig. 1 (c) has a layer structure in which a polarizing plate 3 is laminated on the surface of the second retardation film 2 shown in fig. 1 (b) opposite to the side on which the first retardation film 1 is laminated, with an adhesive layer or an adhesive layer interposed therebetween. Here, the adhesive layer or the pressure-sensitive adhesive layer for bonding the second retardation film 2 and the polarizing plate 3 is not shown. The pressure-sensitive adhesive layer 12 may be a pressure-sensitive adhesive layer for bonding to an organic EL display element, a touch sensor, or the like, as in (a) and (b) of fig. 1. In the optical laminate 102, the first retardation film 1 is composed of a retardation layer 10 and an alignment layer 11.

As shown in fig. 1, the optical laminate of the present invention may have 2 or more retardation films. When a plurality of retardation films are provided in the optical laminate, the puncture elastic modulus of at least 1 retardation film may be 50g/mm or less, and from the viewpoint of suppressing the occurrence of cracks due to temperature changes, it is preferable that the puncture elastic modulus of all the retardation films included in the optical laminate is 50g/mm or less.

If the retardation layer of the retardation film is a layer formed from a composition containing a polymerizable liquid crystal compound (layer obtained by curing a polymerizable liquid crystal compound), the puncture elastic modulus of the present invention can be easily set to 50g/mm or less, which is preferable. The retardation film may have an alignment layer for aligning the polymerizable liquid crystal compound. In addition, in this manufacturing stage, a substrate supporting the alignment layer may be further provided.

The polymerizable liquid crystal compound is a compound having a polymerizable group, and is a compound capable of exhibiting a liquid crystal state. The polymerizable groups of the polymerizable liquid crystal compound react with each other to polymerize the polymerizable liquid crystal compound, thereby curing the polymerizable liquid crystal compound.

The layer obtained by curing the polymerizable liquid crystal compound is formed on, for example, an alignment layer provided on the substrate. The substrate may be a long substrate having a function of supporting the alignment layer. The substrate functions as a releasable support and can support a phase difference layer or an alignment layer for transfer. Further, the surface preferably has a sufficient adhesive strength to enable peeling. The substrate may be a polyolefin-based resin including a light-transmitting (preferably optically transparent) thermoplastic resin, for example, a chain polyolefin-based resin (such as a polypropylene-based resin) or a cyclic polyolefin-based resin (such as a norbornene-based resin); cellulose resins such as triacetyl cellulose and diacetyl cellulose; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; a polycarbonate-based resin; (meth) acrylic resins such as methyl methacrylate resins; a polystyrene-based resin; a polyvinyl chloride resin; acrylonitrile-butadiene-styrene resins; acrylonitrile-styrene resins; polyvinyl acetate resin; a polyvinylidene chloride resin; a polyamide resin; a polyacetal resin; modified polyphenylene ether resin; a polysulfone-based resin; a polyether sulfone-based resin; a polyarylate-based resin; a polyamide imide resin; a polyimide-based resin; a film of maleimide resin or the like.

The thickness of the substrate is not particularly limited, and is preferably in the range of, for example, 20 μm or more and 200 μm or less. If the thickness of the base material is 20 μm or more, strength is imparted.

The base material may be subjected to various anti-blocking treatments. Examples of the anti-blocking treatment include an easy adhesion treatment, a treatment of mixing a filler or the like, and an embossing (knurling treatment). By applying such anti-blocking treatment to the base material, adhesion of the base materials to each other when the base material is wound up, so-called blocking, can be effectively prevented, and the optical film can be manufactured with high productivity.

The layer obtained by curing the polymerizable liquid crystal compound is formed on the substrate with the alignment layer interposed therebetween. That is, the substrate and the alignment layer are laminated in this order, and a layer obtained by curing the polymerizable liquid crystal compound is laminated on the alignment layer.

The alignment layer is not limited to the vertical alignment layer, and may be an alignment layer in which the molecular axis of the polymerizable liquid crystal compound is aligned horizontally or an alignment layer in which the molecular axis of the polymerizable liquid crystal compound is aligned obliquely. The alignment layer is preferably one having solvent resistance that is not dissolved by application of a composition containing a polymerizable liquid crystal compound described later and having heat resistance for use in heat treatment for removal of the solvent or alignment of the liquid crystal compound. Examples of the alignment layer include an alignment layer containing an alignment polymer, a photo-alignment film, and a groove alignment layer in which a concave-convex pattern or a plurality of grooves are formed on the surface thereof and aligned. The thickness of the alignment layer is usually in the range of 10nm to 10000 nm.

The alignment layer has a function of supporting the retardation layer, and can function as a releasable support. The alignment layer may be one which can support the phase difference layer for transfer and has a surface with a sufficient adhesive force to enable peeling.

As the resin used for the alignment layer, a resin obtained by polymerizing a polymerizable compound can be used. The polymerizable compound is a compound having a polymerizable group, and is usually a non-liquid crystal polymerizable non-liquid crystal compound which does not exhibit a liquid crystal state. The polymerizable groups of the polymerizable compound react with each other to polymerize the polymerizable compound, thereby forming a resin. The resin is not particularly limited as long as it is used as an alignment layer for aligning a polymerizable liquid crystal compound in the phase of forming the retardation layer, is not included in the retardation film, and is a resin used as a material of a known alignment layer, and a cured product obtained by curing a conventionally known monofunctional or polyfunctional (meth) acrylate monomer in the presence of a polymerization initiator, or the like can be used. Specifically, examples of the (meth) acrylate monomer include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono-2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, methacrylic acid, and urethane acrylate. The resin may be a mixture of 1 or more of them.

The alignment layer may be peeled off together with the substrate before and after the step of laminating the retardation layer with another optical film or the like.

In addition, the retardation film may include an alignment layer for the purpose of improving the peelability from the substrate and imparting film strength to the retardation film. When the retardation film includes an alignment layer, it is preferable to use, as the resin used for the alignment layer, a cured product obtained by curing a monofunctional or 2-functional (meth) acrylate monomer, an imide monomer, or a vinyl ether monomer, from the viewpoint of the puncture elastic modulus being 50g/mm or less.

Examples of the monofunctional (meth) acrylate monomer include (meth) acrylate having an alkyl group having 4 to 16 carbon atoms, (meth) acrylate having a β -carboxyalkyl group having 2 to 14 carbon atoms, (meth) acrylate having an alkylated phenyl group having 2 to 14 carbon atoms, methoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, and isobornyl (meth) acrylate,

Examples of the 2-functional (meth) acrylate monomer include 1, 3-butanediol di (meth) acrylate; 1, 3-butanediol (meth) acrylate; 1, 6-hexanediol di (meth) acrylate; ethylene glycol di (meth) acrylate; diethylene glycol di (meth) acrylate; neopentyl glycol di (meth) acrylate; triethylene glycol di (meth) acrylate; tetraethylene glycol di (meth) acrylate; polyethylene glycol diacrylate (PEG-diacrylate); bis (acryloyloxyethyl) ether of bisphenol a; ethoxylated bisphenol a di (meth) acrylate; propoxylated neopentyl glycol di (meth) acrylate; ethoxylated neopentyl glycol di (meth) acrylate and 3-methylpentanediol di (meth) acrylate.

Examples of the imide resin obtained by curing an imide monomer include polyamide and polyimide. The imide-based resin may be a mixture of 1 or more of them.

The resin for forming the alignment layer may contain a monomer other than the monofunctional or 2-functional (meth) acrylate monomer, the imide monomer, and the vinyl ether monomer, and the content of the monofunctional or 2-functional (meth) acrylate monomer, the imide monomer, and the vinyl ether monomer may be 50 wt% or more, preferably 55 wt% or more, and more preferably 60 wt% or more of the total monomers.

When the alignment layer is included in the retardation film, the thickness of the alignment layer is usually in the range of 10nm to 10000nm, and when the alignment property of the retardation layer is in-plane alignment with respect to the film surface, the thickness of the alignment layer is preferably 10nm to 1000nm, and when the alignment property of the alignment layer is perpendicular alignment with respect to the film surface, the thickness of the alignment layer is preferably 100nm to 10000 nm. When the thickness of the alignment layer is within the above range, the peeling property of the substrate can be improved and appropriate film strength can be provided.

The type of the polymerizable liquid crystal compound used in the present embodiment is not particularly limited, but the polymerizable liquid crystal compound can be classified into a rod-like type (rod-like liquid crystal compound) and a disk-like type (disk-like liquid crystal compound, discotic liquid crystal compound) in terms of its shape. Further, there are low molecular type and high molecular type, respectively. The term "polymer" generally means a compound having a polymerization degree of 100 or more (physical-phase transition kinetics (trade name: POLYMER: ダ ィ ナ ミ ク ス), native male, Page 2, Kyobo, 1992).

In the present embodiment, any polymerizable liquid crystal compound may be used. Further, 2 or more kinds of rod-like liquid crystal compounds, 2 or more kinds of discotic liquid crystal compounds, or a mixture of rod-like liquid crystal compounds and discotic liquid crystal compounds may be used.

as the rod-like liquid crystal compound, for example, the rod-like liquid crystal compound described in claim 1 of Japanese patent application laid-open No. 11-513019 can be suitably used. As the discotic liquid crystal compound, for example, discotic liquid crystal compounds described in paragraphs [0020] to [0067] of Japanese patent laid-open No. 2007-108732 or paragraphs [0013] to [0108] of Japanese patent laid-open No. 2010-244038 can be suitably used.

The polymerizable liquid crystal compound may be used in combination of 2 or more. In this case, at least 1 species has 2 or more polymerizable groups in the molecule. That is, the layer formed by curing the polymerizable liquid crystal compound is preferably a layer formed by fixing a liquid crystal compound having a polymerizable group by polymerization. In this case, the liquid crystal does not need to be further exhibited after the layer is formed.

The polymerizable liquid crystal compound has a polymerizable group capable of undergoing a polymerization reaction. The polymerizable group is preferably a functional group capable of undergoing an addition polymerization reaction, such as a polymerizable ethylenically unsaturated group or a cyclopolymerizable group. More specifically, examples of the polymerizable group include a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, (meth) acryloyl groups are preferable. The term "meth (acryloyl group" refers to a concept including both a methacryloyl group and an acryloyl group.

As described later, the layer obtained by curing the polymerizable liquid crystal compound can be formed by applying a composition containing the polymerizable liquid crystal compound to, for example, an alignment layer and irradiating the alignment layer with active energy rays. The composition may contain components other than the polymerizable liquid crystal compound. For example, the above composition preferably contains a polymerization initiator. The polymerization initiator used is selected, for example, from thermal polymerization initiators or photopolymerization initiators depending on the form of polymerization reaction. Examples of the photopolymerization initiator include α -carbonyl compounds, acyloin ethers, α -hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, combinations of triarylimidazole dimers and p-aminobenzones, and the like. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the total solid content in the coating liquid.

"cured" in the present invention means that the formed layer is not deformed or fluidized even if it is present alone but can be independently present, and the puncture elastic modulus of the formed layer is usually 3g/mm or more.

The composition may contain a polymerizable monomer in terms of uniformity of the coating film and film strength. Examples of the polymerizable monomer include a radically polymerizable or cationically polymerizable compound. Among them, polyfunctional radical polymerizable monomers are preferable.

As the polymerizable monomer, a polymerizable monomer copolymerizable with the polymerizable liquid crystal compound is preferable. The amount of the polymerizable monomer used is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, based on the total mass of the polymerizable liquid crystal compound.

The composition may contain a surfactant in terms of uniformity of the coating film and film strength. The surfactant may be a conventionally known compound. Among them, fluorine compounds are particularly preferable.

In addition, the composition may contain a solvent, and an organic solvent is preferably used. Examples of the organic solvent include amides (e.g., N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), halogenated alkanes (e.g., chloroform, dichloromethane), esters (e.g., methyl acetate, ethyl acetate, butyl acetate), ketones (e.g., acetone, methyl ethyl ketone), and ethers (e.g., tetrahydrofuran, 1, 2-dimethoxyethane). Among them, halogenated alkanes and ketones are preferable. In addition, 2 or more organic solvents may be used in combination.

The composition may further contain a vertical alignment promoter such as a polarizing plate interface side vertical alignment agent or an air interface side vertical alignment agent; and various alignment agents such as a horizontal alignment promoter such as a polarizing plate interface side horizontal alignment agent and an air interface side horizontal alignment agent. The composition may further contain an adhesion improving agent, a plasticizer, a polymer, and the like in addition to the above components.

The active energy ray includes ultraviolet ray, visible light, electron ray, and X-ray, and preferably ultraviolet ray. Examples of the light source of the active energy ray include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, an LED light source emitting light in a wavelength range of 380nm to 440nm, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.

In general, in the case of an ultraviolet B wave (wavelength range of 280 to 310mm), the irradiation intensity of ultraviolet is 100mW/cm²～3000mW/cm². The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activation of the cationic polymerization initiator or the radical polymerization initiator. The time for ultraviolet irradiation is usually 0.1 second to 10 minutes, preferably 0.1 second to 5 minutes, more preferably 0.1 second to 3 minutes, and still more preferably 0.1 second to 1 minute.

The ultraviolet rays may be irradiated 1 time or a plurality of times. Although it varies depending on the polymerization initiator used, the cumulative light amount at a wavelength of 365nm is preferably 700mJ/cm²More preferably 1100mJ/cm²It is more preferable to set the concentration to 1300mJ/cm²The above. The accumulated light amount is advantageous for increasing the polymerization rate of the polymerizable liquid crystal compound constituting the retardation film and improving heat resistance. The cumulative light amount at a wavelength of 365nm is preferably set to 2000mJ/cm²More preferably 1800mJ/cm²The following. The accumulated light amount may cause coloring of the retardation film. Further, the cooling step may be provided after the irradiation of the ultraviolet rays. The cooling temperature may be, for example, 20 ℃ or lower, or may be 10 ℃ or lower. The cooling time may be, for example, 10 seconds or more, or 20 seconds or more.

In the present embodiment, the thickness of the retardation layer is preferably 0.5 μm or more. The thickness of the retardation layer is preferably 10 μm or less, and more preferably 5 μm or less. The upper limit and the lower limit described above may be arbitrarily combined. When the thickness of the retardation layer is not less than the lower limit, sufficient durability can be obtained. If the thickness of the retardation layer is not more than the upper limit, it can contribute to thinning of the optical laminate. The thickness of the retardation layer can be adjusted so that a desired in-plane retardation value and a retardation value in the thickness direction of the layer to which a retardation of λ/4 is given, the layer to which a retardation of λ/2 is given, or the positive C layer can be obtained.

The retardation film may include a plurality of retardation layers each having different retardation characteristics. Each retardation layer may be laminated with an adhesive or a pressure-sensitive adhesive interposed therebetween, or a composition containing a polymerizable liquid crystal compound may be applied to the surface of an already formed retardation layer and cured.

In the case where the retardation film is formed only from the retardation layer obtained by curing the polymerizable liquid crystal compound, the puncture elastic modulus can be significantly reduced, and therefore, the occurrence of cracks due to thermal shock can be suppressed, which is preferable. When the retardation film is formed of only a retardation layer obtained by curing a polymerizable liquid crystal compound, the puncture elastic modulus of the retardation film may be, for example, 40g/mm or less or 35g/mm or less, preferably 30g/mm or less, more preferably 25g/mm or less, further preferably 15g/mm or less, and usually 3g/mm or more. From the viewpoint of maintaining the film strength, the puncture elastic modulus is preferably 7g/mm or more.

On the other hand, in the case where the retardation film is formed of a retardation layer obtained by curing an alignment layer and a polymerizable liquid crystal compound, the lower limit of the puncture elastic modulus of the retardation film is preferably 15g/mm or more, more preferably 20g/mm or more, and the upper limit thereof may be 50g/mm or less, preferably 40g/mm or less, and more preferably 30g/mm or less (usually 5g/mm or more), from the viewpoints of suppressing cracking due to temperature change and maintaining appropriate peeling property and film strength from the substrate.

As described above, the retardation film of the present invention may be composed of only the retardation layer or may be composed of the retardation layer and the alignment layer, but the amount N of the polymerizable group represented by the following calculation formula (a) in the retardation film is preferably 0.67 or less, and more preferably 0.64 or less.

The amount of the polymerizable group N is usually 0.01 or more, preferably 0.03 or more.

Wherein the content of the first and second substances,

AL represents the number of types of structural units derived from a polymerizable compound constituting a resin constituting an alignment layer constituting a retardation film. When the retardation film is composed of only the retardation layer, AL is 0.

Cwi represents: the content (mass%) of the structural unit derived from the polymerizable compound i based on the whole structural units derived from the polymerizable compound in the resin constituting the alignment layer,

Mi represents the molecular weight of the polymerizable compound i constituting the alignment layer,

Ni represents the number of polymerizable groups of the polymerizable compound i constituting the alignment layer.

LC represents: when the retardation layer is a layer obtained by curing a polymerizable liquid crystal compound, the number of types of the structural units derived from the polymerizable liquid crystal compound constituting the retardation layer is large.

Cwj denotes: the content (% by mass) of the structural unit derived from the polymerizable liquid crystal compound j based on the whole structural units derived from the polymerizable liquid crystal compound in the retardation layer,

Mj represents the molecular weight of the polymerizable liquid crystal compound j constituting the retardation layer,

nj represents the number of polymerizable groups of the polymerizable liquid crystal compound j constituting the retardation layer.

L_ALDenotes the thickness (. mu.m) of the alignment layer, L_LCThe thickness (. mu.m) of the retardation layer is shown. L is_totalRepresents L_ALAnd L_LCand (4) summing.

When a temperature change occurs in a use environment of a display device in which an optical laminate is laminated, expansion and contraction occur in a retardation film, another optical film, an adhesive, or a pressure-sensitive adhesive layer constituting the optical laminate. The influence of dimensional change due to expansion and contraction of other constituent members tends to concentrate on the retardation film. The retardation film cannot follow dimensional changes of other members due to temperature changes, and cracks are likely to occur from the retardation film as a starting point.

Such cracks due to temperature changes are likely to occur when the retardation film is a thin film having a thickness of 10 μm or less or when the retardation film has a retardation layer formed by curing a polymerizable liquid crystal compound. In particular, when the retardation film is formed of the retardation layer or the retardation layer and the alignment layer, and the retardation layer or the alignment layer is directly laminated with the adhesive or the adhesive layer, cracks are likely to occur, and this tendency is sometimes remarkable when the alignment property of the retardation layer has a vertical alignment property such as that of the normal C layer.

In the optical laminate of the present invention, the retardation film is made to have a puncture elastic modulus of 500/mm or less as a constituent element, so that the retardation film can follow dimensional changes of other members due to the temperature change, and the occurrence of cracks can be suitably suppressed even in the configuration of the retardation film or the optical laminate in which cracks are likely to occur.

The optical laminate of the present application may have 2 or more retardation films. When the optical laminate includes a 2-layer retardation film, the 2 layers are preferably a layer giving a retardation of λ/4 and a positive C layer, or a layer giving a retardation of λ/4 and a layer giving a retardation of λ/2. When the optical laminate includes 2 retardation films, the retardation layers of the respective retardation films may be laminated with an adhesive layer or an adhesive layer interposed therebetween. From the viewpoint of making the optical laminate thinner, the thickness of the retardation film in which a plurality of layers are laminated is preferably 3 to 30 μm, and more preferably 5 to 25 μm.

In the case where the optical laminate has 2 or more retardation films in the structure thereof and at least one of the retardation films has a retardation layer exhibiting vertical alignment properties obtained by curing a polymerizable liquid crystal compound, cracks tend to be more likely to occur due to thermal shock. In particular, when the phase difference films are laminated with each other via an active energy ray-curable adhesive and the storage modulus of the adhesive layer is 3000MPa or more, the occurrence of cracks may become remarkable. As a combination of retardation characteristics when the optical laminate has two retardation films, for example, a combination of a retardation film in which the retardation layer has a layer imparting a retardation of λ/4 and a retardation film having a layer imparting vertical alignment properties can be cited. In the optical laminate having such a configuration, the occurrence of cracks can be effectively suppressed by setting the puncture elastic modulus of the retardation film to the range specified in the present application.

When the retardation film contains an alignment layer, the evaluation of the abrasion resistance of the alignment layer, such as pencil hardness or steel wool hardness, can be used as an index for suppressing cracking due to thermal shock.

For example, the pencil hardness is measured in accordance with JIS K5600-5-4: 1999, it is expressed as the hardest pencil hardness at which scratches are not generated when the pencil with each hardness is used for scratching. When the pencil hardness of the alignment layer is 3B or less, generation of cracks due to thermal shock can be suppressed, which is preferable.

The steel wool hardness as other index can be expressed as follows: for example, a cleanroom wiper (BEMCOT AZ-8, manufactured by asahi chemicals) was brought into contact with the surface of the test object with a load of 500g by a steel wool tester (manufactured by gorgeon seikagaku corporation), and a 4-round abrasion test was performed at a speed of 40r/min, and the number of scratches visually observed was represented. The number of scratches measured in the steel wool test for the alignment layer is preferably 4 or more, and more preferably 8 or more, in terms of suppressing the occurrence of cracks due to thermal shock.

The pencil hardness is usually 5B or more, and the number of scratches measured in the steel wool test is usually 50 or less, preferably 20 or less, and more preferably 10 or less, from the viewpoint of handling properties and visibility of a display device such as an organic EL display device.

The photoelastic coefficient of the retardation film is preferably 3X 10^-13Pa^-1～100×10^-13Pa^-1, more preferably 5X 10^-13Pa^-1～70×10^-13Pa^-1More preferably 15X 10^-13Pa^-1～60×10^-13Pa^-1More preferably 20X 10^-13Pa^-1～60×10^-13pa^-1。

For example, a photoelastic coefficient can be calculated from the slope of a function of stress and a phase difference value by measuring the phase difference value (23 ℃/wavelength 550nm) at the center of a sample (dimension 1cm × 10cm) while applying stress (0.5N to 3N) with the sample held between both ends using a phase difference measuring device KOBRA-WPR (manufactured by prince measuring instruments).

The optical stack may have layers other than those shown in figure 1. Examples of the layer that the optical laminate may further have include: optical functional layers such as a front panel, a light-shielding pattern, and a polarizing plate; an adhesive layer or an adhesive layer for laminating with other optical functional layers; touch sensors, and the like. The front panel may be disposed on the opposite side of the polarizing plate 3 from the side on which the retardation film is laminated. The light shielding pattern may be formed on a face of the front panel on the polarizing plate side. The light-shielding pattern is formed on a frame edge (non-display region) of the image display device, and is formed so that the wiring of the image display device is not visible to a user. The touch sensor may be laminated on the optical laminate via an adhesive layer 12.

The optical laminate may have a substantially rectangular main surface. The main surface is a surface having the largest area corresponding to the display surface. Substantially rectangular means: the shape may be a shape obtained by cutting out at least 1 of 4 corners (corner portions) so as to form an obtuse angle or a shape provided with a curvature; or a recess (notch) in which a part of an end surface perpendicular to the main surface is recessed in the in-plane direction; or an opening part in which a part of the main surface is hollowed out in a shape such as a circle, an ellipse, a polygon, or a combination thereof.

The size of the optical laminate is not particularly limited. When the optical laminate is substantially rectangular, the length of the long side is preferably 6cm or more and 35cm or less, more preferably 10cm or more and 30cm or less, and the length of the short side is preferably 5cm or more and 30cm or less, more preferably 6cm or more and 25cm or less.

The thickness of the optical laminate is usually 50 μm to 500 μm, preferably 150 μm or less, more preferably 105 μm or less from the viewpoint of making the optical laminate thin, and if the thickness of the optical laminate is 105 μm or less, cracks starting from the retardation film tend to propagate throughout the optical laminate when subjected to thermal shock.

Even in the optical laminate of such a thin film, the occurrence of cracks due to temperature changes can be suitably suppressed by setting the puncture elastic modulus of the retardation film to the range specified in the present application.

From the viewpoint of suppressing the occurrence of cracks due to thermal shock, a method of reducing the amount of warpage of the retardation film of the present application in a state of a tape substrate is preferable. The amount of warpage can be measured by cutting the laminate with the substrate into a 10cm × 10cm square and humidifying the laminate at 23 ℃ and 55% for 24 hours. The amount of warpage varies depending on the type and thickness of the substrate, and in the case of a cyclic polyolefin resin (COP) film having a substrate of 15 to 25 μm (for example, 20 μm), the average value of the amount of warpage on 4 sides is preferably 10mm or less, and more preferably 5mm or less.

< polarizing plate >

In the present invention, the polarizing plate refers to a polarizer alone or a laminate including a protective film attached to at least 1 surface of a polarizer. The protective film provided in the polarizing film may have a surface treatment layer such as a hard coat layer, an antireflection layer, or an antistatic layer, which will be described later. The polarizing plate and the protective film may be laminated via an adhesive layer or an adhesive layer, for example. Hereinafter, the members provided in the polarizing plate will be described.

(1) Polarizing plate

The polarizing plate may be an absorption-type polarizing plate having a property of absorbing linearly polarized light having a vibration plane parallel to the absorption axis thereof and transmitting linearly polarized light having a vibration plane orthogonal to the absorption axis (parallel to the transmission axis). As the polarizing plate included in the first layer, a polarizing plate obtained by adsorbing and orienting a dichroic dye to a uniaxially stretched polyvinyl alcohol resin film can be suitably used. The polarizing plate can be manufactured by, for example, a method including: a step of uniaxially stretching a polyvinyl alcohol resin film; a step of dyeing the polyvinyl alcohol resin film with a dichroic dye to thereby adsorb the dichroic dye; a step of treating the polyvinyl alcohol resin film having the dichroic dye adsorbed thereon with a crosslinking liquid such as an aqueous boric acid solution; and a step of washing the treated product with water after the treatment with the crosslinking solution.

As the polyvinyl alcohol resin, a polyvinyl alcohol resin obtained by saponifying a polyvinyl acetate resin can be used. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable therewith, and the like can be mentioned. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, (meth) acrylamides having an ammonium group, and the like.

In the present specification, "(meth) acrylic" means at least one selected from acrylic and methacrylic. The same applies to "(meth) acryloyl group", "meth (acrylate)" and the like.

The saponification degree of the polyvinyl alcohol resin is usually 85 mol% to 100 mol%, and preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal, polyvinyl acetal, or the like modified with aldehydes may be used. The polyvinyl alcohol resin has an average polymerization degree of usually 1000 to 10000, preferably 1500 to 5000. The average polymerization degree of the polyvinyl alcohol resin can be determined in accordance with JIS K6726.

A film formed of such a polyvinyl alcohol resin is used as a material film of a polarizing plate (polarizing plate). The method for forming the film from the polyvinyl alcohol resin is not particularly limited, and a known method can be used. The thickness of the polyvinyl alcohol-based material film is not particularly limited, and a polyvinyl alcohol-based material film having a thickness of 5 to 35 μm is preferably used so that the thickness of the polarizing plate is 15 μm or less. More preferably 20 μm or less.

The uniaxial stretching of the polyvinyl alcohol resin film may be performed before, simultaneously with, or after the dyeing of the dichroic dye. In the case where the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before or during the crosslinking treatment. In addition, uniaxial stretching may be performed in a plurality of stages thereof.

In the case of uniaxial stretching, the uniaxial stretching may be performed between rolls having different peripheral speeds, or the uniaxial stretching may be performed using a heat roll. The uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which stretching is performed in a state where the polyvinyl alcohol resin film is swollen with a solvent or water. The draw ratio is usually 3 to 8 times.

As a method for dyeing a polyvinyl alcohol resin film with a dichroic dye, for example, a method of immersing the film in an aqueous solution containing a dichroic dye is employed. As the dichroic dye, iodine or a dichroic organic dye is used. The polyvinyl alcohol resin film is preferably subjected to an immersion treatment in water before the dyeing treatment.

As the crosslinking treatment after dyeing with the dichroic dye, a method of immersing the dyed polyvinyl alcohol resin film in an aqueous solution containing boric acid is generally employed. In the case of using iodine as the dichroic dye, the aqueous solution containing boric acid preferably contains potassium iodide.

The thickness of the polarizing plate is usually 30 μm or less, preferably 15 μm or less, more preferably 13 μm or less, still more preferably 10 μm or less, and particularly preferably 8 μm or less. The thickness of the polarizing plate is usually 2 μm or more, preferably 3 μm or more.

As the polarizing plate, for example, a polarizing plate having a dichroic dye oriented in a cured film obtained by polymerizing a liquid crystal compound as described in japanese patent application laid-open No. 2016-170368 can be used. As the dichroic dye, a dichroic dye having absorption in a wavelength range of 380 to 800nm can be used, and an organic dye is preferably used. Examples of the dichroic dye include azo compounds. The liquid crystal compound is a liquid crystal compound which can be polymerized in an oriented state, and may have a polymerizable group in a molecule. Further, as described in WO2011/024891, the polarizing plate may be formed of a dichroic dye having liquid crystallinity.

The contraction force of the polarizing plate is preferably 2.0N/2mm or less, more preferably 1.8N/2mm or less, and still more preferably 1.5N/2mm or less.

(2) Protective film

The polarizing plate of the present invention may have a protective film on at least 1 surface of the polarizer. When a protective film is provided between the polarizing plate and the retardation film, it preferably has negative birefringence. Here, the negative birefringence means that a slow axis appears in a direction perpendicular to the stretching direction of the resin. It is considered that since a retardation film including a retardation layer having positive birefringence is used as the retardation film, a retardation opposite to the retardation of the retardation film developed by thermal shrinkage of the polarizing plate appears, and thus color change is small. Here, the positive birefringence means that a slow axis appears in a direction parallel to the stretching direction of the retardation film.

The protective film to be laminated on the polarizing plate may be a film made of a polyolefin-based resin including a light-transmitting (preferably optically transparent) thermoplastic resin, for example, a chain polyolefin-based resin (such as a polypropylene-based resin) or a cyclic polyolefin-based resin (such as a norbornene-based resin); cellulose resins such as triacetyl cellulose and diacetyl cellulose; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; a polycarbonate-based resin; (meth) acrylic resins such as methyl methacrylate resins; a polystyrene-based resin; a polyvinyl chloride resin; acrylonitrile-butadiene-styrene resins; acrylonitrile-styrene resins; polyvinyl acetate resin; a polyvinylidene chloride resin; a polyamide resin; a polyacetal resin; modified polyphenylene ether resin; a polysulfone-based resin; a polyether sulfone-based resin; a polyarylate-based resin; a polyamide imide resin; a polyimide-based resin; a film of maleimide resin or the like.

In particular, a protective film having negative birefringence is preferably used as the protective film used between the polarizing plate and the retardation film. That is, it is preferable to use a film containing at least 1 resin selected from the group consisting of a (meth) acrylic resin, a polystyrene resin, and a maleimide resin. By using such a resin film as a protective film, a polarizing plate having excellent durability can be obtained even when processed into an irregular shape.

The (meth) acrylic resin is a resin containing a compound having a (meth) acryloyl group as a main constituent monomer. Specific examples of the (meth) acrylic resin include, for example: poly (meth) acrylates such as polymethyl methacrylate; methyl methacrylate- (meth) acrylic acid copolymer; methyl methacrylate- (meth) acrylate copolymers; methyl methacrylate-acrylate- (meth) acrylic acid copolymer; methyl (meth) acrylate-styrene copolymers (MS resins and the like); copolymers of methyl methacrylate and a compound having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylic acid norbornyl ester copolymer, etc.). Preferably, a poly (meth) acrylic acid C such as poly (methyl (meth) acrylate) is used_1-6The polymer containing an alkyl ester as a main component is more preferably a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

The in-plane retardation value Re of the (meth) acrylic resin film at a wavelength of 590nm is preferably 10nm or less, more preferably 7nm or less, still more preferably 5nm or less, particularly preferably 3nm or less, and most preferably 1nm or less. The retardation value Rth in the thickness direction of the (meth) acrylic resin film at a wavelength of 590nm is preferably 15nm or less, more preferably 10nm or less, still more preferably 5nm or less, particularly preferably 3nm or less, and most preferably 1nm or less. If the in-plane retardation value and the thickness direction retardation value are in such ranges, color change during the heat resistance test can be suppressed without impairing the characteristics of the retardation film. In order to set the in-plane retardation value and the thickness direction retardation value within such ranges, for example, a (meth) acrylic resin having a glutarimide structure described later can be used.

The (meth) acrylic resin preferably has a structural unit that exhibits positive birefringence within a range having negative birefringence. If the structural unit exhibiting positive birefringence and the structural unit exhibiting negative birefringence are present, the ratio of the presence of the structural units can be adjusted to suppress the retardation of the (meth) acrylic resin film, and a (meth) acrylic resin film having a low retardation can be obtained. Examples of the structural unit exhibiting positive birefringence include: a structural unit constituting a lactone ring, polycarbonate, polyvinyl alcohol, cellulose acetate, polyester, polyarylate, polyimide, polyolefin, or the like; a structural unit represented by the following general formula (1). Examples of the structural unit exhibiting negative birefringence include: structural units derived from styrene monomers, maleimide monomers, and the like; structural units of polymethyl methacrylate; a structural unit represented by the following general formula (3).

As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure or a glutarimide structure is preferably used. The (meth) acrylic resin having a lactone ring structure or a glutarimide structure is excellent in heat resistance. More preferably a (meth) acrylic resin having a glutarimide structure. When a (meth) acrylic resin having a glutarimide structure is used, a (meth) acrylic resin film having low moisture permeability and small retardation and ultraviolet transmittance can be obtained as described above. (meth) acrylic resins having a glutarimide structure (hereinafter also referred to as glutarimide resins) are described in, for example, Japanese patent application laid-open Nos. 2006-. These descriptions are incorporated herein by reference.

The above glutarimide resin preferably contains a structural unit represented by the following general formula (1) (hereinafter also referred to as a glutarimide unit) and a structural unit represented by the following general formula (2) (hereinafter also referred to as a (meth) acrylate unit).

[ solution 1]

In the formula (1), R¹And R²Each independently hydrogen or C1-C8 alkyl, R³The substituent is hydrogen, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aromatic ring having 5 to 15 carbon atoms. In the formula (2), R⁴And R⁵Each independently hydrogen or C1-C8 alkyl, R⁶The substituent is hydrogen, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aromatic ring having 5 to 15 carbon atoms.

The glutarimide resin may further contain a structural unit represented by the following general formula (3) (hereinafter also referred to as an aromatic vinyl unit) as needed.

[ solution 2]

In the formula (3), R⁷Is hydrogen or alkyl of 1-8 carbon atoms, R⁸Is 6E carbon atoms10 is an aryl group.

In the above general formula (1), R is preferably¹And R²Each independently is hydrogen or methyl, R³Is hydrogen, methyl, butyl or cyclohexyl; further preferably, R¹Is methyl, R²Is hydrogen, R³Is methyl.

The glutarimide resin may contain only a single type of glutarimide unit, or may contain R in the general formula (1)¹、R²And R³A plurality of different categories.

The glutarimide unit can be formed by imidizing a (meth) acrylate unit represented by the above general formula (2). Alternatively, the glutarimide unit may be a half ester of an acid anhydride such as maleic anhydride or a mixture of such an acid anhydride and a linear or branched alcohol having 1 to 20 carbon atoms; acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, fumaric acid, citraconic acid, and other α, β -ethylenically unsaturated carboxylic acids.

In the above general formula (2), R is preferably⁴And R⁵Each independently is hydrogen or methyl, R⁶is hydrogen or methyl; further preferably, R⁴Is hydrogen, R⁵Is methyl, R⁶Is methyl.

The glutarimide resin may contain only a single type of (meth) acrylate unit, or may contain R in the general formula (2)⁴、R⁵And R⁶A plurality of different categories.

In the glutarimide resin, the aromatic vinyl unit represented by the general formula (3) preferably contains styrene, α -methylstyrene, or the like, and more preferably contains styrene. By having such an aromatic vinyl unit, the positive birefringence of the glutarimide structure can be reduced, and a (meth) acrylic resin film having a lower retardation can be obtained.

The above glutarimide resin may contain only a single type of aromatic vinyl unit or may contain a single type of aromatic vinyl unitR⁷And R⁸A plurality of different categories.

The content of the above glutarimide unit in the above glutarimide resin is preferably determined in accordance with, for example, R³The structure of (a) and the like. The content of the glutarimide unit is preferably 1 to 80% by weight, more preferably 1 to 70% by weight, still more preferably 1 to 60% by weight, and particularly preferably 1 to 50% by weight, based on the total structural units of the glutarimide resin. When the content of the glutarimide unit is in such a range, a (meth) acrylic resin film having a low retardation and excellent heat resistance can be obtained.

The content of the aromatic vinyl unit in the glutarimide resin may be appropriately set according to the purpose or desired characteristics. The content of the aromatic vinyl unit may be 0 depending on the use. When the aromatic vinyl unit is contained, the content thereof is preferably 10 to 80% by weight, more preferably 20 to 80% by weight, further preferably 20 to 60% by weight, and particularly preferably 20 to 50% by weight, based on the glutarimide unit of the glutarimide resin. When the content of the aromatic vinyl unit is in such a range, a (meth) acrylic resin film having a low phase difference and excellent heat resistance and mechanical strength can be obtained.

If necessary, the above glutarimide resin may further contain a structural unit other than the glutarimide unit, the (meth) acrylate unit, and the aromatic vinyl unit. Examples of the other structural units include structural units derived from nitrile monomers such as acrylonitrile and methacrylonitrile, and maleimide monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide. These other structural units may be directly copolymerized in the above-mentioned glutarimide resin or may be graft-copolymerized.

The (meth) acrylic resin film may contain any appropriate additive according to the purpose. Examples of additives include: hindered phenol-based, phosphorus-based, sulfur-based antioxidants; stabilizers such as light-resistant stabilizers, ultraviolet absorbers, weather-resistant stabilizers, and heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; a near infrared ray absorber; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate, and antimony oxide; antistatic agents such as anionic, cationic and nonionic surfactants; colorants such as inorganic pigments, organic pigments, and dyes; organic fillers, inorganic fillers; a resin modifier; a plasticizer; a lubricant; a retardation reducing agent, etc. The kind, combination, content and the like of the additives to be contained may be appropriately set according to the purpose or the desired characteristics.

The method for producing the (meth) acrylic resin film is not particularly limited, and for example, the (meth) acrylic resin, the ultraviolet absorber, and other polymers and additives as needed may be sufficiently mixed by any appropriate mixing method to prepare a thermoplastic resin composition in advance, and then the thermoplastic resin composition may be subjected to film molding. Alternatively, the (meth) acrylic resin, the ultraviolet absorber, and if necessary, other polymers, additives, and the like may be prepared into respective solutions, mixed, prepared into a uniform mixed solution, and then subjected to film forming.

In order to produce the thermoplastic resin composition, the film raw materials are premixed using any suitable mixer such as an OMNI mixer, and the resulting mixture is extrusion-kneaded. In this case, the mixer used for extrusion kneading is not particularly limited, and any appropriate mixer such as an extruder such as a single-screw extruder or a twin-screw extruder, or a pressure kneader may be used.

Examples of the method of film formation include any appropriate film formation methods such as a solution casting method (solution casting method), a melt extrusion method, a calendering method, and a compression molding method. Melt extrusion is preferred. The melt extrusion method does not use a solvent, and therefore, can reduce the production cost and the load of the solvent on the global environment or the work environment.

Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature is preferably 150 to 350 ℃, and more preferably 200 to 300 ℃.

In the case of film formation by the T-die method, a T-die may be attached to the tip of a known single-screw extruder or twin-screw extruder, and the film extruded in the form of a film may be wound to obtain a rolled film. In this case, the uniaxial stretching may be performed by applying stretching in the extrusion direction while appropriately adjusting the temperature of the take-up roll. Further, simultaneous biaxial stretching, sequential biaxial stretching, or the like may be performed by stretching the film in a direction perpendicular to the extrusion direction.

The (meth) acrylic resin film may be either an unstretched film or a stretched film as long as the desired retardation can be obtained. In the case of the stretched film, it may be a uniaxially stretched film or a biaxially stretched film. In the case of the biaxially stretched film, the biaxially stretched film may be either a simultaneously biaxially stretched film or a sequentially biaxially stretched film.

The stretching temperature is preferably in the vicinity of the glass transition temperature of the thermoplastic resin composition as a film raw material, specifically, preferably in the range of (glass transition temperature-30 ℃) to (glass transition temperature +30 ℃), more preferably in the range of (glass transition temperature-20 ℃) to (glass transition temperature +20 ℃). If the stretching temperature is insufficient (glass transition temperature-30 ℃), the haze of the obtained film becomes large, or the film may be cracked or broken, and a predetermined stretching ratio may not be obtained. On the other hand, when the stretching temperature exceeds (glass transition temperature +30 ℃), the thickness unevenness of the obtained film becomes large, or the mechanical properties such as elongation, tear propagation strength, and rubbing fatigue resistance tend not to be sufficiently improved. Further, there is a tendency that a failure such as adhesion of the film to the roller easily occurs.

The stretching ratio is preferably 1.1 to 3 times, and more preferably 1.3 to 2.5 times. When the stretch ratio is in such a range, the mechanical properties of the film, such as elongation, tear propagation strength, and rolling fatigue resistance, can be greatly improved. As a result, a film having small thickness unevenness, substantially zero birefringence (and thus small retardation), and further having small haze can be produced.

The (meth) acrylic resin film may be subjected to a heat treatment (annealing) after the stretching treatment in order to stabilize the optical isotropy and mechanical properties. The conditions for the heat treatment may be any suitable conditions.

The photoelastic coefficient of the (meth) acrylic resin film is preferably-3 Pa^-1～-100×10^-13Pa^-1More preferably-5 Pa^-1～-70×10^-13Pa^-1More preferably-15 Pa^-1～-50×10^-13Pa^-1. The photoelastic coefficient can be measured by the above-described method.

The thickness of the (meth) acrylic resin film is preferably 10 to 200. mu.m, more preferably 20 to 100. mu.m. If the thickness is less than 10 μm, the strength may be lowered. If the thickness exceeds 200. mu.m, the transparency may be lowered.

When protective films are laminated on both sides of the polarizing plate, the same films as described above may be laminated on both sides, and other resin films may be used. For example, an olefin resin film, a polyester resin film, and a cellulose resin film are preferably used.

Examples of the chain polyolefin resin include homopolymers of chain olefins such as polyethylene resins (polyethylene resins, which are homopolymers of ethylene, and copolymers mainly composed of ethylene), and polypropylene resins (polypropylene resins, which are homopolymers of propylene, and copolymers mainly composed of propylene), and copolymers containing 2 or more kinds of chain olefins.

The cyclic polyolefin resin is a general term for resins obtained by polymerizing a cyclic olefin as a polymerization unit, and examples thereof include those described in Japanese patent application laid-open Nos. 1-240517, 3-14882, and 3-122137. Specific examples of the cyclic polyolefin resin include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins with linear olefins such as ethylene and propylene (typically random copolymers), graft polymers obtained by modifying these with unsaturated carboxylic acids or derivatives thereof, and hydrogenated products of these. Among them, norbornene-based resins using norbornene-based monomers such as norbornene or polycyclic norbornene-based monomers as cyclic olefins are preferably used.

The polyester resin is a resin having an ester bond excluding the following cellulose ester resins, and is generally a polycondensate of a polycarboxylic acid or a derivative thereof and a polyol. As the polycarboxylic acid or a derivative thereof, a 2-membered dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. As the polyol, a 2-membered diol can be used, and examples thereof include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A typical example of the polyester resin is polyethylene terephthalate, which is a condensation product of terephthalic acid and ethylene glycol.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, copolymers thereof, or cellulose ester resins in which a part of the hydroxyl groups is modified with other substituents may be mentioned. Among them, cellulose triacetate (triacetyl cellulose) is particularly preferable.

The thickness of the protective film is usually 1 μm to 100 μm, and from the viewpoint of strength, handling properties, and the like, it is preferably 5 μm to 60 μm, more preferably 10 μm to 55 μm, and still more preferably 15 μm to 40 μm.

As described above, the protective film may be one having a surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an optical diffusion layer, an antireflection layer, a low refractive index layer, an antistatic layer, and an antifouling layer on its outer surface (surface opposite to the polarizing plate). The thickness of the protective film is a thickness including the thickness of the surface treatment layer.

The protective film may be attached to the polarizer via, for example, an adhesive layer or an adhesive layer. As the adhesive for forming the adhesive layer, an aqueous adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and an aqueous adhesive or an active energy ray-curable adhesive is preferable. As the pressure-sensitive adhesive layer, a pressure-sensitive adhesive layer described later can be used.

Examples of the aqueous adhesive include an adhesive containing a polyvinyl alcohol resin aqueous solution, and an aqueous two-pack type urethane emulsion adhesive. Among them, an aqueous adhesive containing an aqueous solution of a polyvinyl alcohol resin is suitably used. As the polyvinyl alcohol resin, in addition to a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of vinyl acetate, a polyvinyl alcohol copolymer obtained by saponifying a copolymer of vinyl acetate and another monomer copolymerizable therewith, a modified polyvinyl alcohol polymer obtained by partially modifying hydroxyl groups thereof, and the like can be used. The aqueous adhesive may contain a crosslinking agent such as an aldehyde compound (e.g., glyoxal), an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.

When an aqueous adhesive is used, it is preferable to perform a drying step for removing water contained in the aqueous adhesive after the polarizing plate and the protective film are bonded. A curing step of curing at a temperature of, for example, 20 to 45 ℃ may be provided after the drying step.

The active energy ray-curable adhesive is an adhesive containing a curable compound that is cured by irradiation with an active energy ray such as an ultraviolet ray, a visible light, an electron beam, or an X-ray, and is preferably an ultraviolet ray-curable adhesive.

The curable compound may be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of the cationically polymerizable curable compound include an epoxy compound (a compound having 1 or 2 or more epoxy groups in a molecule), an oxetane compound (a compound having 1 or 2 or more oxetane rings in a molecule), and a combination thereof. Examples of the radically polymerizable curable compound include a (meth) acrylic compound (a compound having 1 or 2 or more (meth) acryloyloxy groups in the molecule), another vinyl compound having a radically polymerizable double bond, and a combination thereof. The cationically polymerizable curable compound and the radically polymerizable curable compound may be used in combination. The active energy ray-curable adhesive usually further contains a cationic polymerization initiator and/or a radical polymerization initiator for initiating a curing reaction of the curable compound.

When the polarizing plate and the protective film are bonded, at least one of the bonding surfaces may be subjected to a surface activation treatment in order to improve the adhesiveness. Examples of the surface activation treatment include: dry treatments such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment and the like), flame treatment, ozone treatment, UV ozone treatment, ionizing active ray treatment (ultraviolet ray treatment, electron ray treatment and the like); a wet treatment such as an ultrasonic treatment, a saponification treatment, and an anchor coating treatment using a solvent such as water or acetone. These surface activation treatments may be performed individually or in combination of 2 or more.

When protective films are bonded to both surfaces of a polarizing plate, adhesives used for bonding these protective films may be the same type of adhesive or different types of adhesives.

The above adhesive or the bonding method using the adhesive may be used not only for bonding a polarizing plate and a protective film but also for bonding other optical functional layers included in the optical laminate of the present invention. For example, when the optical laminate has 2 or more retardation films, the optical laminate can be used for bonding the retardation films to each other.

< adhesive layer >

The pressure-sensitive adhesive layer 12 may be composed of a pressure-sensitive adhesive composition containing a resin such as a (meth) acrylic resin, a rubber resin, a urethane resin, an ester resin, a silicone resin, or a polyvinyl ether resin as a main component. Among them, the pressure-sensitive adhesive composition is suitable for use as a base polymer of a (meth) acrylic resin excellent in transparency, weather resistance, heat resistance and the like. The adhesive composition may be an active energy ray-curable type or a thermosetting type. The thickness of the adhesive layer is usually 3 to 30 μm, preferably 3 to 25 μm.

As the (meth) acrylic resin (base polymer) used in the adhesive composition, a polymer or copolymer containing, as a monomer, 1 or 2 or more kinds of (meth) acrylic acid esters such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate is suitably used. The base polymer is preferably copolymerized with a polar monomer. Examples of the polar monomer include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, and the like, such as (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, meth (acrylamide), N-dimethylaminoethyl (meth) acrylate, and glycidyl (meth) acrylate.

The adhesive composition may be an adhesive composition comprising only the above-mentioned base polymer, and typically further comprises a crosslinking agent. Examples of the crosslinking agent include: a metal ion having a valence of 2 or more, which forms a metal carboxylate with a carboxyl group; polyamine compounds forming amide bonds with carboxyl groups; polyepoxy compounds or polyols which form ester bonds with carboxyl groups; and a polyisocyanate compound forming an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferable.

The pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition are described as examples of the pressure-sensitive adhesive layer 12 used for bonding the optical laminate of the present invention and the organic EL display device, but the pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition are not limited thereto. For example, the optical laminate of the present invention may be used for bonding other optical functional layers and for bonding optical functional layers constituting the optical laminate.

< front Panel >

The front panel is disposed on the viewing side of the polarizing plate. The front panel may be laminated on the polarizing plate with an adhesive layer interposed therebetween. Examples of the adhesive layer include the above adhesive layer and adhesive layer. As shown in fig. 2, the front panel 5 may be laminated on the polarizing plate 3 with an adhesive layer not shown interposed therebetween. The front panel 5 may be formed with a light shielding pattern 6 as shown in fig. 2.

Examples of the front panel include glass, and a front panel including a hard coat layer on at least one surface of a resin film. As the glass, for example, high-permeability glass or tempered glass can be used. In particular, when a thin transparent surface material is used, chemically strengthened glass is preferable. The thickness of the glass may be, for example, 100 μm to 5 mm.

The front panel including the hard coating layer on at least one side of the resin film may have a flexible characteristic, unlike the conventional glass. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 μm to 100 μm.

The resin film may be a resin film made of a cycloolefin derivative having a unit of a cycloolefin-containing monomer such as a norbornene or polycyclic norbornene-based monomer, cellulose (diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl cellulose, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose) ethylene-vinyl acetate copolymer, polycycloolefin, polyester, polystyrene, polyamide, polyetherimide, polyacrylic acid, polyimide, polyamideimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyvinyl acetate, Films made of polymers such as polycarbonate, polyurethane, and epoxy resin. As the resin film, an unstretched film, a uniaxially stretched film or a biaxially stretched film can be used. These polymers may be used alone or in combination of 2 or more. As the resin film, a polyamideimide film or a polyimide film excellent in transparency and heat resistance, a uniaxially or biaxially stretched polyester film, a cycloolefin derivative film excellent in transparency and heat resistance and capable of coping with the enlargement of the film, a polymethyl methacrylate film, and a triacetyl cellulose and isobutyl cellulose film excellent in transparency and free of optical anisotropy are preferable. The thickness of the resin film may be 5 to 200. mu.m, preferably 20 to 100. mu.m.

The hard coat layer may be formed by curing a hard coat composition containing a reactive material that forms a cross-linked structure by irradiation of light or thermal energy. The hard coat layer can be formed by curing a hard coat layer composition containing both a photocurable (meth) acrylate monomer or oligomer and a photocurable epoxy monomer or oligomer. The photocurable (meth) acrylate monomer may include 1 or more selected from epoxy (meth) acrylate, urethane (meth) acrylate, and polyester (meth) acrylate. The epoxy (meth) acrylate can be obtained by reacting a carboxylic acid having a (meth) acryloyl group with an epoxy compound.

The hard coating composition may further include one or more selected from a solvent, a photoinitiator, and an additive. The additive may include one or more selected from inorganic nanoparticles, a leveling agent, and a stabilizer, and may further include, for example, an antioxidant, a UV absorber, a surfactant, a lubricant, an antifouling agent, and the like, which are each generally used in the art.

< light-shielding Pattern >

The light shielding pattern may be provided as at least a portion of a bezel (bezel) or a case of the front panel or the display device to which the front panel is applied. The light blocking pattern may be formed on the display element side of the front panel. The light blocking pattern may hide the respective wirings of the display device from a user. The color and/or material of the light-shielding pattern is not particularly limited, and may be formed of a resin substance having a plurality of colors such as black, white, gold, and the like. In one embodiment, the thickness of the light-shielding pattern may be 2 to 50 μm, may be preferably 4 to 30 μm, and may be more preferably 6 to 15 μm. In addition, in order to suppress the mixing of bubbles due to the difference in height between the light-shielding pattern and the display portion and the visibility of the boundary portion, a shape may be given to the light-shielding pattern.

< touch sensor >

Touch sensors are used as input means. As the touch sensor, various types such as a resistive film type, a surface acoustic wave type, an infrared ray type, an electromagnetic induction type, and a capacitance type have been proposed, and any type may be used. Among them, the electrostatic capacitance system is preferable. The capacitive touch sensor is divided into an active region and an inactive region located in an outer region of the active region. The active region is a region corresponding to a region (display portion) where a screen is displayed in the display panel, and is a region where a user's touch is sensed, and the inactive region is a region corresponding to a region (non-display portion) where a screen is not displayed in the image display device. The touch sensor may include: a substrate; a sensing pattern formed on the active region of the substrate; and each sensing line formed in the inactive region of the substrate and used for connecting the sensing pattern with an external driving circuit via the pad portion. As the substrate, glass or the same material as the resin film constituting the front panel can be used. The substrate of the touch sensor preferably has a toughness of 2000 MPa% or more in order to suppress cracking of the touch sensor. The toughness may be more preferably 2000 MPa% or more and 30000 MPa% or less.

The sensing pattern may have 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 from each other. The first pattern and the second pattern are formed in the same layer, and in order to sense a touched point, the patterns must be electrically connected. The first pattern is in a form in which the cell patterns are connected to each other by the connectors, and the second pattern is in a structure in which the cell patterns are separated from each other in an island form, and therefore, an additional bridge electrode is required to electrically connect the second patterns. The sensing pattern may employ a known transparent electrode material. Examples thereof include 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 Nanotubes (CNT), graphene, and metal wires, and 2 or more of them may be used alone or in combination. ITO may be preferably used. The metal used in the wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, tellurium, chromium, and the like. These may be used alone or in combination of 2 or more.

The bridge electrode may be formed on the insulating layer with the insulating layer interposed therebetween, or 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, or may be formed of a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of 2 or more of these metals. The first pattern and the second pattern must be electrically insulated, and thus an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the contact of the first pattern and the bridge electrode, or may be formed to cover the layer of the sensing pattern. In the latter case, the bridge electrode may connect the second pattern via a contact hole formed in the insulating layer. The touch sensor may further include an optical adjustment layer between the substrate and the electrode as a means for appropriately compensating for a difference in transmittance between a patterned region where a pattern is formed and a non-patterned region where no pattern is formed, specifically, a difference in light transmittance induced by a difference in refractive index of these regions, and the optical adjustment layer may include an inorganic insulating substance or an organic insulating substance. The optical adjustment layer can be formed by applying a photocurable composition containing a photocurable organic binder and a solvent onto a substrate. The photocurable composition may further comprise inorganic particles. The refractive index of the optical adjustment layer can be increased by the inorganic particles.

The photocurable organic binder may include a copolymer of monomers such as an acrylate monomer, a styrene monomer, and a carboxylic acid monomer. The photocurable organic binder may be a copolymer containing, for example, repeating units different from each other 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 contain various additives such as a photopolymerization initiator, a polymerizable monomer, and a curing assistant.

< method for producing optical layered body >

A method for producing an optical laminate will be described with reference to the optical laminate shown in fig. 1 (a) to (c) as an example.

The optical laminate 100 (fig. 1 (a)) can be produced, for example, as follows. An alignment layer 11 is formed on a substrate, and a coating liquid containing a polymerizable liquid crystal compound is applied on the alignment layer 11. The polymerizable liquid crystal compound is cured by heat treatment or irradiation with active energy rays in a state where the polymerizable liquid crystal compound is aligned. After the polymerizable liquid crystal compound is cured to form the retardation layer 10, the substrate is peeled off, and the pressure-sensitive adhesive layer 12 formed on the release film is laminated on the surface of the alignment layer 11 after the substrate is peeled off.

In the case of the optical laminate 101 shown in fig. 1 (b), the same is applied until the optical laminate 100 shown in fig. 1 (a) and the retardation layer 10 are formed, and after the retardation layer 10 is formed, the retardation layer 10 and the second phase difference film are laminated with the adhesive layer 13 interposed therebetween. When the optical laminate 100 and the retardation layer 10 are long, the respective members may be bonded to each other through the adhesive layer 13 in a roll-to-roll (roll) manner. After the optical laminate 100 and the second phase difference film were laminated, the substrate was peeled off, and the pressure-sensitive adhesive layer 12 formed on the release film was laminated on the surface of the alignment layer 11 after the substrate was peeled off.

In the case of the optical laminate 102 shown in fig. 1 (c), the polarizing plate 3 is first manufactured. The polarizing plate 3 can be manufactured by laminating a polarizer and a protective film with an adhesive layer interposed therebetween. The protective film may be laminated on at least one surface of the polarizing plate. The polarizing plate may be manufactured by preparing a long member, bonding the members in a roll-to-roll manner, and then cutting the long member into a predetermined shape, or by cutting the long member into a predetermined shape and bonding the long member to the predetermined shape. The polarizing plate may be provided with a heating step or a humidity conditioning step after the protective film is bonded thereto. Similarly to the optical laminate 101 of fig. 1 (b), the retardation film is laminated to the second retardation film, and the surface of the second retardation film opposite to the adhesive layer 13 is laminated to the polarizing plate 3 with the adhesive layer or the pressure-sensitive adhesive layer interposed therebetween. When the polarizing plate 3 or the optical laminate 101 is long, the respective members may be bonded to each other in a roll-to-roll manner. After the polarizing plate 3 was laminated, the substrate was peeled off, and the pressure-sensitive adhesive layer 12 formed on the release film was laminated on the surface of the alignment layer 11 after the peeling of the substrate.

Then, the release film laminated on the pressure-sensitive adhesive layer 12 is peeled off, and the optical laminate and the organic EL display element are bonded via the pressure-sensitive adhesive layer 12, whereby an organic EL display device can be manufactured.

< use >

The optical laminate of the present invention can be used in 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 EL display device, an inorganic electroluminescence (hereinafter also referred to as an inorganic EL) display device, an electron emission display device (for example, a field emission display device (also referred to as an FED) or a surface field emission display device (also referred to as an SED)), the liquid crystal display device includes any of a transmissive liquid crystal display device, a transflective liquid crystal display device, and the like, and these display devices may be either a display device that displays a two-dimensional image or a stereoscopic display device that displays a three-dimensional image.

In fig. 2, the organic EL display device 103 has a layer structure in which an optical layered body is layered on the organic EL display element 4 via the pressure-sensitive adhesive layer 12 layered on the retardation film 1.

The display device may be a flexible display device, and may be a flexible organic EL display device. The flexible organic EL display device includes the optical laminate of the present invention and an organic EL display element. The optical laminate of the present invention is disposed on the viewing side of the organic EL display element and has a bendable structure. Bendable means that bending can be performed without causing cracks or fractures. When the optical laminate of the present invention is applied to a flexible organic EL display device, the optical laminate preferably includes at least one of a front panel and a touch sensor.

specific examples of the optical laminate include: a front panel, a polarizing plate, a retardation film, and a touch sensor are laminated in this order from the viewing side; or a front panel, a touch sensor, a polarizing plate, and a retardation film are laminated in this order from the viewing side. The presence of the polarizing plate on the viewing side of the touch sensor is preferable because it makes it difficult to observe the pattern of the touch sensor, and the visibility of the displayed image is improved. The respective members may be laminated using an adhesive, or the like. Further, the liquid crystal display device may further include a light-shielding pattern formed on at least one surface of any one of the front panel, the polarizing plate, the retardation film, and the touch sensor.