JP2021036325A - Optical laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical laminate having a polarizing plate and a retardation film, which can suppress the occurrence of cracks even when subjected to a thermal impact.
An optical laminate having a polarizing plate and a retardation film, the retardation film presses the tip of a piercing jig perpendicularly to a film surface, and the piercing occurs when a break occurs. The puncture elastic modulus calculated by the following formula (1) using the stress F (g) applied to the retardation film from the tip of the jig and the strain amount S (mm) of the retardation film is 50 g / mm. An optical laminate characterized by the following.

(1) Puncture elastic modulus (g / mm) = F (g) / S (mm)

[Selection diagram] Fig. 1

Description

The present invention relates to an optical laminate.

In recent years, image display devices typified by organic electroluminescence (hereinafter, also referred to as organic EL) display devices have rapidly become widespread. The organic EL display device is equipped with a circular polarizing plate including a polarizer and a retardation film, and an optical laminate on which other optical functional layers are laminated.

As a retardation film for an image display device such as an organic EL display device, a stretched conventional resin film or a film formed of a liquid crystal compound as a material has been studied, and there is a demand for a thinner image display device. As the strength increases, the retardation film and the optical laminate provided with the retardation film are also required to be thinner (see, for example, Patent Document 1). An optical laminate having such a retardation film may have cracks starting from the retardation film due to expansion and contraction due to a temperature change. Especially when a sudden temperature change (thermal shock) is applied, cracks are likely to occur. When such a crack occurs, not only the durability of the optical laminate but also the visibility of the display device may be deteriorated.

JP-A-2017-102286

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

The present invention provides an optical laminate represented by the following [1] to [5].
[1] An optical laminate having a retardation film, the retardation film presses the tip of the piercing jig perpendicularly to the film surface, and when a break occurs, the tip of the piercing jig is pressed. The puncture elastic modulus calculated by the following formula (1) using the stress F (g) applied to the retardation film and the strain amount S (mm) of the retardation film is 50 g / mm or less. An optical laminate characterized by.

(1) Puncture elastic modulus (g / mm) = F (g) / S (mm)

[2] The retardation film is the optical laminate of [1] containing a retardation layer in which a polymerizable liquid crystal compound is cured.
[3] The retardation film is the optical laminate of [2] further including an alignment layer.
[4] The retardation layer is an optical laminate of [2] or [3] having vertical orientation.
[5] The optical laminate is any of [1] to [4] that further has a polarizing plate.
The present invention also provides a display device shown by the following [6].
[6] A display device in which the optical laminate according to any one of [1] to [5] is laminated on a display element.

According to the present invention, it is possible to provide an optical laminate having a retardation film and capable of suppressing the occurrence of cracks even in an environment subject to a sudden temperature change.

(A) to (c) are examples of schematic cross-sectional views showing the layer structure of the optical laminate of the present invention. This is an example of a schematic cross-sectional view showing a layer structure of an organic EL display device. It is schematic cross-sectional view which shows the layer structure at the time of the thermal shock test using the optical laminate produced in Examples 1-6, and Comparative Examples 1 and 2.

(Definition of terms and symbols)
Definitions of terms and symbols herein are as follows.
(1) Puncture elastic modulus The stress F (g) applied to the film from the tip of the piercing jig and the through hole when the tip of the piercing jig is pressed perpendicularly to the film surface and breakage occurs. Alternatively, it is a physical property value of the film defined by using the strain amount S (mm) generated in the film before fracture occurs, and is expressed as a proportional constant (stress F / strain S) between the stress F and the strain S.
The puncture elastic modulus can be measured with a compression tester equipped with a load cell. Examples of the compression tester include the puncture tester "NDG5" manufactured by Kato Tech Co., Ltd. and the handy compression tester "KES-". G5 ”, small desktop testing machine“ EZ Test ”of Shimadzu Corporation, etc. can be mentioned. From the stress-strain curve that can be determined by using such a compression tester, it is possible to measure the stress applied to the film when fracture occurs and the amount of strain generated in the film up to that point.
The breakage that occurs in the film when the piercing jig is pressed includes the case where the tip of the jig creates a through hole in the film.
(2) Orientation layer A layer having an ability to regulate the direction of the molecular axis of the polymerizable liquid crystal compound forming the retardation layer so as to have a desired retardation characteristic is shown. The cured layer (phase difference layer) of the polymerizable liquid crystal compound is formed on the substrate via the alignment layer. Examples of the alignment layer include an alignment layer containing an orientation polymer, a photoalignment film, and a grub alignment layer in which an uneven pattern or a plurality of grooves are formed and oriented on the surface.
(3) Vertical Orientation 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 laminated surface of each layer constituting the optical laminate. A positive C layer is a typical example of a retardation layer exhibiting vertical orientation.
(4) Refractive index (nx, ny, nz)
“Nx” is the refractive index in the direction in which the in-plane refractive index is maximized (that is, the slow-phase axis direction), “ny” is the direction orthogonal to the slow-phase axis in the in-plane, and “nz” is the thickness direction. Refractive index.
(5) In-plane retardation value The in-plane retardation value (Re [λ]) refers to the in-plane retardation value of the film at 23 ° C. and a wavelength of λ (nm). Re [λ] is obtained by Re [λ] = (nx−ny) × d, where d (nm) is the thickness of the film.
(6) Phase difference value in the thickness direction The in-plane retardation value (Rth [λ]) refers to the phase difference value in the thickness direction of the film at 23 ° C. and a wavelength of λ (nm). Rth [λ] is obtained by Rth [λ] = ((nx + ny) /2-nz) × d, where d (nm) is the thickness of the film.

<Optical laminate>
The optical laminate of the present invention has a retardation film, and the puncture elastic modulus of the retardation film is 50 g / mm or less. Further, the retardation film has a retardation layer. The retardation layer preferably has a layer composed of a composition containing a polymerizable liquid crystal compound. The layer composed of the composition containing the polymerizable liquid crystal compound specifically means a layer in which the polymerizable liquid crystal compound is cured. In the present specification, a layer giving a phase difference of λ / 2, a layer giving a phase difference of λ / 4 (positive A layer), a positive C layer, and the like are collectively referred to as a retardation layer. Further, the retardation film may include an alignment layer described later.

Hereinafter, an example of the layer structure of the optical laminate of the present invention will be described with reference to FIG. The optical laminate 100 shown in FIG. 1A 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 can 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) is a second retardation film via an adhesive layer 13 on a surface opposite to the alignment layer 11 of the retardation layer 10 of FIG. 1 (a). It has a layered structure in which 2 is laminated. Similar to FIG. 1A, the pressure-sensitive adhesive layer 12 can be a pressure-sensitive adhesive layer for bonding to an organic EL display element or the like. 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 an adhesive layer or an adhesive on the surface opposite to the first retardation film 1 of the second retardation film 2 of FIG. 1 (b). It has a layer structure in which the polarizing plate 3 is laminated via a layer. 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 can be a pressure-sensitive adhesive layer for bonding to an organic EL display element, a touch sensor, or the like, as in FIGS. 1 (a) and 1 (b). 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 two or more retardation films. When a plurality of retardation films are provided in the optical laminate, the puncture elastic modulus of at least one retardation film may be 50 g / mm or less, but from the viewpoint of suppressing the generation of cracks due to temperature changes, the optical laminates are optically laminated. It is preferable that the puncture elastic modulus of all the retardation films contained in the body is 50 g / mm or less.

When the retardation layer of the retardation film is a layer composed of a composition containing a polymerizable liquid crystal compound (a layer obtained by curing the polymerizable liquid crystal compound), the puncture elastic modulus of the present invention may be 50 g / mm or less. It is preferable because it becomes easy. Further, the retardation film may have an alignment layer for orienting the polymerizable liquid crystal compound. Further, in the manufacturing stage thereof, a base material for supporting the alignment layer may be further provided.

The polymerizable liquid crystal compound is a compound having a polymerizable group and can be in a liquid crystal state. The polymerizable liquid crystal compound is cured by reacting the polymerizable groups of the polymerizable liquid crystal compound with each other to polymerize the polymerizable liquid crystal compound.
The cured layer of the polymerizable liquid crystal compound is formed on, for example, an orientation layer provided on the base material. The base material may be a long base material having a function of supporting the alignment layer. This base material functions as a releasable support and can support a retardation layer or an orientation layer for transfer. Further, it is preferable that the surface has an adhesive force that can be peeled off. The base material is a translucent (preferably optically transparent) thermoplastic resin such as a chain polyolefin resin (polypropylene resin or the like) or a cyclic polyolefin resin (norbornen resin or the like). Polyolefin resin; Cellulosic resin such as triacetyl cellulose and diacetyl cellulose; Polyester resin such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate resin; (Meta) acrylic resin such as methyl methacrylate resin; Polystyrene resin; Polyvinyl chloride resin; Acrylonitrile / butadiene / styrene resin; Acrylonitrile / styrene resin; Polyvinyl acetate resin; Polyvinylidene chloride resin; Polyacetal resin; Polyacetal resin; Modified polyphenylene ether resin; A film made of a polysulfone-based resin; a polyethersulfone-based resin; a polyarylate-based resin; a polyamideimide-based resin; a polyimide-based resin; a maleimide-based resin, or the like can be used.

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

The base material may be subjected to various blocking prevention treatments. Examples of the blocking prevention treatment include an easy-adhesion treatment, a treatment of kneading a filler and the like, an embossing treatment (knurling treatment) and the like. By applying such a blocking prevention treatment to the base material, it is possible to effectively prevent the base materials from sticking to each other when the base material is wound, so-called blocking, and to manufacture an optical film with high productivity. Is possible.

The cured layer of the polymerizable liquid crystal compound is formed on the substrate via the alignment layer. That is, the base material and the alignment layer are laminated in this order, and the layer on which the polymerizable liquid crystal compound is cured is laminated on the alignment layer.

The alignment layer is not limited to the vertically oriented layer, and may be an oriented layer that horizontally aligns the molecular axis of the polymerizable liquid crystal compound, or may be an oriented layer that obliquely orients the molecular axis of the polymerizable liquid crystal compound. .. The alignment layer has solvent resistance that does not dissolve due to coating of a composition containing a polymerizable liquid crystal compound, which will be described later, and heat resistance in heat treatment for removing the solvent and aligning the liquid crystal compound. preferable. Examples of the alignment layer include an alignment layer containing an orientation polymer, a photoalignment film, and a grub alignment layer in which an uneven pattern or a plurality of grooves are formed and oriented on the surface. The thickness of the oriented layer is usually in the range of 10 nm to 10000 nm.

Further, the alignment layer has a function of supporting the retardation layer and may function as a releasable support. A retardation layer for transfer can be supported, and the surface thereof may have an adhesive force that can be peeled off.

As the resin used for the alignment layer, a resin obtained by polymerizing a polymerizable compound is used. The polymerizable compound is a compound having a polymerizable group, and is usually a non-liquid crystalline non-liquid crystal compound that does not become a liquid crystal state. The polymerizable groups of the polymerizable compound react with each other to polymerize the polymerizable compound, thereby forming a resin. Such a resin is used as an alignment layer for orienting a polymerizable liquid crystal compound at the stage of forming the retardation layer, and if it is not contained in the retardation film, it is used as a material for a known alignment layer. The resin is not particularly limited, and a cured product obtained by curing a conventionally known monofunctional or polyfunctional (meth) acrylate-based monomer under a polymerization initiator can be used. Specifically, examples of the (meth) acrylate-based monomer include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, and trimethyl propantriacrylate. , 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, urethane acrylate and the like can be exemplified. The resin may be one of these or a mixture of two or more.
The alignment layer can be peeled off together with the base material before and after the step of forming the retardation layer and then laminating it with another optical film or the like.

Further, an orientation layer can be included in the retardation film for the purpose of improving the peelability from the substrate and imparting film strength to the retardation film. When the retardation film contains an alignment layer, a monofunctional or bifunctional (meth) acrylate-based monomer, an imide-based monomer, or a vinyl ether-based monomer is used as the resin used for the alignment layer from the viewpoint of piercing elastic modulus of 50 g / mm or less. It is preferable to use a cured product or the like that has been cured.
Examples of the monofunctional (meth) acrylate-based monomer include alkyl (meth) acrylates having 4 to 16 carbon atoms, βcarboxyalkyl (meth) acrylates having 2 to 14 carbon atoms, and alkylated phenyl (meth) having 2 to 14 carbon atoms. Examples thereof include acrylate, methoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate and isobonyl (meth) acrylate, and examples of the bifunctional (meth) acrylate-based 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; tri Ethylene glycol di (meth) acrylate; tetraethylene glycol di (meth) acrylate; polyethylene glycol diacrylate; bisphenol A bis (acryloyloxyethyl) ether; ethoxylated bisphenol A di (meth) acrylate; propoxylated neopentyl glycol di (Meta) Acrylate; Examples thereof include ethoxylated neopentyl glycol di (meth) acrylate and 3-methylpentanediol di (meth) acrylate.
Examples of the imide-based resin obtained by curing the imide-based monomer include polyamide and polyimide. The imide-based resin may be one of these or a mixture of two or more.
Further, the resin forming the alignment layer may contain a monomer other than the monofunctional or bifunctional (meth) acrylate-based monomer, the imide-based monomer and the vinyl ether-based monomer, but the monofunctional or bifunctional (meth) The content ratio of the acrylate-based monomer, the imide-based monomer, and the vinyl ether-based monomer may be 50% by weight or more, preferably 55% by weight or more, and more preferably 60% by weight or more in the total monomer. ..

When the alignment layer is included in the retardation film, the thickness of the alignment layer is usually in the range of 10 nm to 10,000 nm, and when the orientation of the alignment layer is in-plane orientation with respect to the film surface, the thickness of the alignment layer is It is preferably 10 nm to 1000 nm, and when the orientation of the alignment layer is perpendicular to the film surface, it is preferably 100 nm to 10000 nm. When the thickness of the oriented layer is within the above range, the peelability of the base material can be improved and appropriate film strength can be imparted.

The type of the polymerizable liquid crystal compound used in the present embodiment is not particularly limited, but is classified into a rod-shaped type (rod-shaped liquid crystal compound) and a disk-shaped type (disk-shaped liquid crystal compound, discotic liquid crystal compound) according to its shape. it can. Further, there are a low molecular weight type and a high molecular weight type, respectively. The polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992).

In this embodiment, any polymerizable liquid crystal compound can be used. Further, two or more kinds of rod-shaped liquid crystal compounds, two or more kinds of disk-shaped liquid crystal compounds, or a mixture of a rod-shaped liquid crystal compound and a disk-shaped liquid crystal compound may be used.

As the rod-shaped liquid crystal compound, for example, the compound described in claim 1 of JP-A-11-513019 can be preferably used. As the disk-shaped liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 or paragraphs [0013] to [0108] of JP-A-2010-244038 are preferable. Can be used for.

Two or more kinds of polymerizable liquid crystal compounds may be used in combination. In that case, at least one type has two or more polymerizable groups in the molecule. That is, the cured layer of 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, it is no longer necessary to exhibit liquid crystallinity after forming a layer.

The polymerizable liquid crystal compound has a polymerizable group capable of carrying out a polymerization reaction. As the polymerizable group, for example, a functional group capable of an addition polymerization reaction such as a polymerizable ethylenically unsaturated group or a ring-polymerizable group is preferable. More specifically, examples of the polymerizable group include a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, the (meth) acryloyl group is preferable. The (meth) acryloyl group is a concept that includes both a meta-acryloyl group and an acryloyl group.

As will be described later, the cured layer of the polymerizable liquid crystal compound can be formed by applying a composition containing the polymerizable liquid crystal compound onto, for example, an alignment layer and irradiating it with active energy rays. The composition may contain components other than the above-mentioned polymerizable liquid crystal compound. For example, the composition preferably contains a polymerization initiator. As the polymerization initiator used, for example, a thermal polymerization initiator or a photopolymerization initiator is selected according to the type of the polymerization reaction. For example, examples of the photopolymerization initiator include α-carbonyl compounds, acyloin ethers, α-hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, and combinations of triarylimidazole dimers and p-aminophenyl ketones. 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.
The term "cured" in the present invention means that the formed layer alone can exist independently without being deformed or flowed, and the puncture elastic modulus of the formed layer is usually 3 g / mm or more.

Further, the composition may contain a polymerizable monomer from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Among them, a polyfunctional radically polymerizable monomer is preferable.

The polymerizable monomer is preferably one that can be copolymerized with the above-mentioned polymerizable liquid crystal compound. 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.

Further, the composition may contain a surfactant from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the surfactant include conventionally known compounds. Among them, fluorine-based 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 amide (eg, N, N-dimethylformamide), sulfoxide (eg, dimethyl sulfoxide), heterocyclic compound (eg, pyridine), hydrocarbon (eg, benzene, hexane), alkyl halide (eg, eg). , Chloroform, dichloromethane), esters (eg, methyl acetate, ethyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Among them, alkyl halides and ketones are preferable. Further, two or more kinds of organic solvents may be used in combination.

Further, the composition includes a vertical alignment promoter such as a polarizer interface side vertical alignment agent and an air interface side vertical alignment agent, and a horizontal alignment promotion agent such as a polarizer interface side horizontal alignment agent and an air interface side horizontal alignment agent. Various orienting agents such as agents may be included. Further, the composition may contain an adhesion improver, a plasticizer, a polymer and the like in addition to the above components.

The active energy beam includes ultraviolet rays, visible light, electron beams, and X-rays, and is preferably ultraviolet rays. 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 excima laser, and a wavelength range. Examples thereof include an LED light source that emits 380 to 440 nm, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.

The irradiation intensity of ultraviolet radiation is typically the case of ultraviolet B wave (wavelength region ^{280～310Nm),} a ^{100mW / cm 2 ~3,000mW / cm 2} . The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating the cationic polymerization initiator or the radical polymerization initiator. The time for irradiating with ultraviolet rays is usually 0.1 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and even more preferably 0.1 seconds. ~ 1 minute.

Ultraviolet rays can be irradiated once or in a plurality of times. Depending on the polymerization initiator used, the accumulated amount of light at a wavelength of 365nm is preferably in a 700 mJ / cm ² or more, more preferably, to 1,100mJ / cm ² or more, 1,300mJ / cm ² or more and It is more preferable to do so. The integrated light intensity is advantageous for increasing the polymerization rate of the polymerizable liquid crystal compound constituting the retardation film and improving the heat resistance. Integrated light intensity at a wavelength of 365nm is preferably in a 2,000 mJ / cm ² or less, and more preferably to 1,800mJ / cm ² or less. The integrated light intensity may cause coloring of the retardation film. Further, a cooling step may be provided after irradiation with ultraviolet rays. The cooling temperature can be, for example, 20 ° C. or lower, and can be 10 ° C. or lower. The cooling time can be, for example, 10 seconds or more, and 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 above-mentioned upper limit value and lower limit value can be arbitrarily combined. When the thickness of the retardation layer is at least the above lower limit value, sufficient durability can be obtained. When the thickness of the retardation layer is not more than the upper limit value, it can contribute to thinning the optical laminate. As the thickness of the retardation layer, a desired in-plane retardation value of a layer giving a retardation of λ / 4, a layer giving a retardation of λ / 2, or a positive C layer, and a retardation value in the thickness direction can be obtained. Can be adjusted.
The retardation film may include a film in which a plurality of retardation layers having different retardation characteristics are laminated. Each of the retardation layers may be laminated via an adhesive or an adhesive, or a composition containing a polymerizable liquid crystal compound may be applied to the surface of the already formed retardation layer and cured. ..

When 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 crack generation due to thermal shock can be suppressed, which is preferable. When the retardation film is formed only from the retardation layer obtained by curing the polymerizable liquid crystal compound, the puncture modulus of the retardation film can be, for example, 40 g / mm or less or 35 g / mm or less, preferably 35 g / mm or less. It is 30 g / mm or less, more preferably 25 g / mm or less, still more preferably 15 g / mm or less, and usually 3 g / mm or more. From the viewpoint of maintaining the film strength, the puncture elastic modulus is preferably 7 g / mm or more.

On the other hand, when the retardation film is formed from a retardation layer and an alignment layer obtained by curing a polymerizable liquid crystal compound, the retardation film is positioned from the viewpoint of suppressing cracks due to temperature changes, maintaining appropriate releasability from a substrate and film strength. The lower limit of the puncture modulus of the retardation film is preferably 15 g / mm or more, more preferably 20 g / mm or more, and the upper limit is 50 g / mm or less, preferably 40 g / mm or less, further preferably 30 g / mm. It can be mm or less (usually 5 g / mm or more).

で示される重合性基量Ｎが０．６７以下、さらには０．６４以下であることが好ましい。
重合性基量Ｎは通常０．０１以上、好ましくは０．０３以上である。
ここで、
ＡＬは、位相差フィルムを構成する配向層を構成する樹脂を構成する重合性化合物に由来する構成単位の種類数を示す。なお、位相差フィルムが位相差層のみから構成されている場合には、ＡＬ＝０である。
Ｃｗｉは、配向層を構成する樹脂における重合性化合物に由来する全構成単位を基準として、重合性化合物ｉに由来する構成単位の含有量（質量％）を示し、
Ｍｉは、配向層を構成する重合性化合物ｉの分子量を示し、
Ｎｉは、配向層を構成する重合性化合物ｉが有する重合性基の数を示す。
ＬＣは、位相差層が重合性液晶化合物の硬化した層である場合に、位相差層を構成する重合性液晶化合物に由来する構成単位の種類数を示す。
Ｃｗｊは、位相差層における重合性液晶化合物に由来する全構成単位を基準として、重合性液晶化合物ｊに由来する構成単位の含有量（質量％）を示し、
Ｍｊは、位相差層を構成する重合性液晶化合物ｊの分子量を示し、
Ｎｊは、位相差層を構成する重合性液晶化合物ｉが有する重合性基の数を示す。
Ｌ_ＡＬは配向層の厚さ（μｍ）を示し、Ｌ_ＬＣは位相差層の厚さ（μｍ）を示す。
Ｌ_{ｔｏｔａｌ}は、Ｌ_ＡＬとＬ_ＬＣとの和を示す。 As described above, the retardation film of the present invention may be composed of only the retardation layer or the alignment layer, and the retardation film may be composed of the retardation layer and the alignment layer. Equation (A)

The polymerizable group amount N represented by (1) is preferably 0.67 or less, more preferably 0.64 or less.
The polymerizable group amount N is usually 0.01 or more, preferably 0.03 or more.
here,
AL indicates the number of types of structural units derived from the polymerizable compound that constitutes the resin that constitutes the alignment layer that constitutes the retardation film. When the retardation film is composed of only the retardation layer, AL = 0.
Cwi indicates the content (mass%) of the structural units derived from the polymerizable compound i, based on all the structural units derived from the polymerizable compound in the resin constituting the alignment layer.
Mi indicates the molecular weight of the polymerizable compound i constituting the alignment layer.
Ni indicates the number of polymerizable groups contained in the polymerizable compound i constituting the alignment layer.
LC indicates the number of types of structural units derived from the polymerizable liquid crystal compound constituting the retardation layer when the retardation layer is a cured layer of the polymerizable liquid crystal compound.
Cwj indicates the content (mass%) of the structural units derived from the polymerizable liquid crystal compound j with reference to all the structural units derived from the polymerizable liquid crystal compound in the retardation layer.
Mj indicates the molecular weight of the polymerizable liquid crystal compound j constituting the retardation layer.
Nj indicates the number of polymerizable groups contained in the polymerizable liquid crystal compound i constituting the retardation layer.
L _AL denotes the thickness of the alignment layer _{(μm), L LC} denotes the thickness of the retardation layer ([mu] m).
L _total indicates the sum of L _AL and _LLC.

When a temperature change occurs in the usage environment of the display device in which the optical laminates are laminated, expansion and contraction occur in the retardation film, other optical films, adhesives, and adhesive layers constituting the optical laminate. The influence of dimensional changes due to expansion and contraction of other components tends to concentrate on the retardation film. The retardation film cannot follow the dimensional change of other members due to the temperature change, and cracks are likely to occur starting from the retardation film.
Cracks due to such a temperature change are likely to occur when the retardation film is a thin film of 10 μm or less or when the retardation film has a retardation layer in which the polymerizable liquid crystal compound is cured. In particular, when the retardation film is formed from the retardation layer or the retardation layer and the alignment layer, and the pressure-sensitive adhesive or the adhesive layer is directly laminated on the retardation layer or the alignment layer, cracks are likely to occur, and the orientation of the retardation layer is likely to occur. However, when it has a vertical orientation such as a positive C layer, the tendency may become remarkable.
In the optical laminate of the present application, by setting the puncture elastic modulus of the retardation film, which is a component thereof, to 50 g / mm or less, the retardation film can follow the dimensional change of other members due to the above-mentioned temperature change. The occurrence of cracks can be suitably suppressed even in the above-mentioned constitution of a retardation film or an optical laminate in which cracks are likely to occur.

The optical laminate of the present application may have two or more retardation films. When the optical laminate contains two layers of retardation films, the two layers provide a λ / 4 phase difference and a positive C layer, or a λ / 4 phase difference and a λ / 2 phase difference. It is preferably a layer.
When the optical laminate contains two layers of retardation films, the retardation layers of the respective retardation films may be laminated via an adhesive layer or an adhesive layer. From the viewpoint of thinning the optical laminate, the thickness of the retardation film in which a plurality of layers are laminated is preferably 3 to 30 μm, more preferably 5 to 25 μm.

In the configuration of the optical laminate, when there are two or more retardation films and at least one of the retardation films has a retardation layer exhibiting vertical orientation in which the polymerizable liquid crystal compound is cured, cracks are caused by thermal impact. Tends to occur more easily. In particular, when the retardation films are laminated with each other via an active energy ray-curable adhesive and the storage elastic modulus of the adhesive layer is 3000 MPa or more, the occurrence of cracks may become remarkable. As a combination of the retardation characteristics when the optical laminate has two retardation films, for example, the retardation layer has a retardation film having a layer giving a retardation of λ / 4 and a layer giving vertical orientation. A combination of retardation films can be mentioned. Even in an optical laminate having such a configuration, the occurrence of cracks can be efficiently suppressed by setting the puncture elastic modulus of the retardation film within the range specified in the present application.

When the retardation film contains an alignment layer, evaluation of abrasion resistance such as pencil hardness and steel wool hardness of the alignment layer can be used as an index for suppressing cracks due to thermal shock.
For example, the pencil hardness is determined according to JIS K 5600-5-4: 1999, and is represented by the hardness of the hardest pencil that does not cause scratches when scratched with a pencil of each hardness. When the pencil hardness of the alignment layer is 3B or less, crack generation due to thermal shock can be suppressed, which is preferable.
For the steel wool hardness as another index, for example, a steel wool testing machine (manufactured by Daiei Seiki Co., Ltd.) is used to bring a clean room wiper (BEMCOT AZ-8 manufactured by Asahi Kasei Co., Ltd.) into contact with the surface to be tested with a load of 500 g. The four reciprocating wear test is performed at a speed of 40 r / min, and the number of scratches confirmed visually can be indicated. The number of scratches measured in the steel wool test on the oriented layer is preferably 4 or more, and more preferably 8 or more, in order to suppress the generation of cracks due to thermal shock.
From the viewpoint of handleability and visibility of display devices such as organic EL display devices, the pencil hardness is usually 5B or more, and the number of scratches measured in the steel wool test is usually 50 or less, and 20 or less. It is preferably present, and more preferably 10 or less.

The photoelastic coefficient of the retardation film is preferably 3 to 100 × 10 ^-13 Pa ^-1 , more preferably 5 to 70 × 10 ^-13 Pa ^-1 , and even more preferably 15 to 60 × 10 ^-13 Pa. ^{It is -1} , and even more preferably 20 to 60 × 10 ^-13 Pa ^-1 . For the photoelastic coefficient, for example, using a phase difference measuring device KOBRA-WPR (manufactured by Oji Measuring Instruments Co., Ltd.), both ends of the sample (size 1 cm × 10 cm) are sandwiched and stress (0.5N to 3N) is applied. The phase difference value (23 ° C./wavelength 550 nm) at the center of the sample can be measured while multiplying, and can be calculated from the slope of the function of the stress and the phase difference value.

The optical laminate can have layers other than those shown in FIG. Layers that the optical laminate may further include include an optical functional layer such as a front plate, a light-shielding pattern, and a polarizing plate, an adhesive layer or an adhesive layer for laminating with another optical functional layer, a touch sensor, and the like. Can be mentioned. The front plate can be arranged on the side of the polarizing plate 3 opposite to the side on which the retardation film is laminated. The light-shielding pattern can be formed on the surface of the front plate on the polarizing plate side. The shading pattern is formed on the frame (non-display area) of the image display device so that the wiring of the image display device is not visible to the user. The touch sensor can be laminated on the optical laminate via the adhesive layer 12.

The shape of the main surface of the optical laminate can be substantially rectangular. The main surface means the surface having the largest area corresponding to the display surface. A substantially rectangular shape is a shape in which at least one of the four corners (corners) is cut off at an obtuse angle, a rounded shape, or an end face perpendicular to the main surface. A part of the main surface has a recess (notch) that is recessed in the in-plane direction, or a part of the main surface is hollowed out into a shape such as a circle, an ellipse, a polygon, or a combination thereof. It means that you may have it.

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 6 cm or more and 35 cm or less, more preferably 10 cm or more and 30 cm or less, and the length of the short side is 5 cm or more and 30 cm or less. It is preferably 6 cm or more and 25 cm or less.

The thickness of the optical laminate is usually 50 to 500 μm, but from the viewpoint of thinning, it is preferably 150 μm or less, more preferably 105 μm or less, but when the thickness of the optical laminate is 105 μm or less, it receives a thermal shock. At this time, cracks originating from the retardation film tend to spread over the entire optical laminate.
Even in such an optical laminate of thin films, the occurrence of cracks due to temperature changes can be suitably suppressed by setting the puncture elastic modulus of the retardation film within the range specified in the present application.

In the retardation film of the present application, it is preferable to reduce the amount of curl with the base material from the viewpoint of suppressing the generation of cracks due to thermal shock. The amount of curl can be measured after controlling the humidity at 23 ° C. and 55% for 24 hours by cutting out into a 10 cm × 10 cm square with a base material. The curl amount varies depending on the type and thickness of the base material, but in the case of a cyclic polyolefin resin (COP) film having a base material of 15 to 25 μm (for example, 20 μm), the average value of the curl amount on four sides is preferably 10 mm or less. Further, 5 mm or less is preferable.

<Polarizer>
In the present invention, the polarizing plate refers to a laminate composed of a polarizing element alone or a protective film bonded to at least one surface of the polarizer. The protective film included in the polarizing film may have a surface treatment layer such as a hard coat layer, an antireflection layer, and an antistatic layer, which will be described later. The polarizer and the protective film can be laminated, for example, via an adhesive layer or an adhesive layer. The members included in the polarizing plate will be described below.

(1) Polarized light The polarizer provided by the polarizing plate absorbs linearly polarized light having a vibrating surface parallel to its absorption axis and transmits linearly polarized light having a vibrating surface orthogonal to the absorption axis (parallel to the transmission axis). It can be an absorption type polarizer having properties. As the polarizing element of the first layer, a polarizer in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol-based resin film can be preferably used. The polarizer is, for example, a step of uniaxially stretching a polyvinyl alcohol-based resin film; a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye; It can be produced by a method including a step of treating the alcohol-based resin film with a cross-linking solution such as an aqueous boric acid solution; and a step of washing with water after the treatment with the cross-linking solution.

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable with the vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group.

As used herein, the term "(meth) acrylic" means at least one selected from acrylic and methacrylic. The same applies to "(meth) acryloyl", "(meth) acrylate" and the like.

The degree of saponification of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually 1000 to 10000, preferably 1500 to 5000. The average degree of polymerization of the polyvinyl alcohol-based resin can be determined in accordance with JIS K 6726.

A film formed of such a polyvinyl alcohol-based resin is used as a raw film for a polarizer (polarizer). The method for forming a film of the polyvinyl alcohol-based resin is not particularly limited, and a known method is adopted. The thickness of the polyvinyl alcohol-based raw film is not particularly limited, but in order to reduce the thickness of the polarizer to 15 μm or less, it is preferable to use one having a thickness of 5 to 35 μm. More preferably, it is 20 μm or less.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing the dichroic dye, at the same time as dyeing, or after dyeing. If the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before the cross-linking treatment or during the cross-linking treatment. Moreover, uniaxial stretching may be performed in these a plurality of steps.

In uniaxial stretching, rolls having different peripheral speeds may be uniaxially stretched, or thermal rolls may be used to uniaxially stretch the rolls. The uniaxial stretching may be a dry stretching in which the film is stretched in the atmosphere, or a wet stretching in which the polyvinyl alcohol-based resin film is swollen with a solvent or water. The draw ratio is usually 3 to 8 times.

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

As the cross-linking treatment after dyeing with a dichroic dye, a method of immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution is usually adopted. When iodine is used as the dichroic pigment, the boric acid-containing aqueous solution preferably contains potassium iodide.

The thickness of the polarizer 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 polarizer is usually 2 μm or more, preferably 3 μm or more.

As the polarizer, for example, as described in JP-A-2016-170368, a dichroic dye may be oriented in a cured film in which a liquid crystal compound is polymerized. As the dichroic dye, those having absorption in the wavelength range of 380 to 800 nm can be used, and it is preferable to use an organic dye. Examples of the dichroic dye include an azo compound. The liquid crystal compound is a liquid crystal compound that can be polymerized while being oriented, and can have a polymerizable group in the molecule. Further, as described in WO2011 / 024891, a polarizer may be formed from a dichroic dye having a liquid crystallinity.

The contractile force of the polarizer is preferably 2.0 N / 2 mm or less, more preferably 1.8 N / mm or less, and further preferably 1.5 N or less.

(2) Protective film The polarizing plate of the present invention may have a protective film on at least one surface of the polarizer. When a protective film is provided between the polarizer and the retardation film, it is preferable to have negative birefringence. Here, the negative birefringence means that the slow-phase axis appears in the direction perpendicular to the stretching direction of the resin. Since a retardation film containing a retardation layer having positive birefringence is used, a retardation opposite to that of the retardation film due to thermal shrinkage of the polarizer is exhibited. It is considered that the color change becomes small. Here, the positive birefringence means that the slow axis appears in the direction parallel to the stretching direction of the retardation film.

The protective film laminated on the polarizer is a translucent (preferably optically transparent) thermoplastic resin, for example, a chain polyolefin resin (polypropylene resin or the like), a cyclic polyolefin resin (norbornene resin, etc.). Polyethylene resin such as triacetyl cellulose, diacetyl cellulose; polyester resin such as polyethylene terephthalate, polybutylene terephthalate; polycarbonate resin; (meth) such as methyl methacrylate resin. Acrylic resin; Polystyrene resin; Polyvinyl chloride resin; Acrylonitrile / butadiene / styrene resin; Acrylonitrile / styrene resin; Polyvinyl acetate resin; Polyvinylidene chloride resin; Polyamide resin; Polyacetal resin; Modified polyphenylene A film made of an ether resin; a polysulfone resin; a polyether sulfone resin; a polyarylate resin; a polyamideimide resin; a polyimide resin; a maleimide resin or the like can be used.

In particular, the protective film used between the polarizer and the retardation film preferably has negative birefringence. That is, it is preferable to use a film containing at least one selected from the group consisting of (meth) acrylic resin, polystyrene resin, and maleimide resin. By using such a resin film as a protective film, it is possible to obtain a polarizing plate having excellent durability even when it is processed into a deformed 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 poly (meth) acrylic acid esters such as polymethyl methacrylate; methyl methacrylate- (meth) acrylic acid copolymers; methyl methacrylate- (meth) acrylic acid. Ester copolymer; methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymer; (meth) methyl acrylate-styrene copolymer (MS resin, etc.); methyl methacrylate and alicyclic hydrocarbon group It contains a copolymer with a compound having (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). _{Preferably, a polymer containing poly (meth) acrylic acid C 1-6} alkyl ester as a main component, such as methyl poly (meth) acrylate, is used, and more preferably, methyl methacrylate as a main component (50 to 100) is used. A methyl methacrylate-based resin having a weight of% by weight, preferably 70 to 100% by weight) is used.

The in-plane retardation value Re of the (meth) acrylic resin film at a wavelength of 590 nm is preferably 10 nm or less, more preferably 7 nm or less, still more preferably 5 nm or less, and particularly preferably 3 nm or less. Yes, most preferably 1 nm or less.
The retardation value Rth in the thickness direction of the (meth) acrylic resin film at a wavelength of 590 nm is preferably 15 nm or less, more preferably 10 nm or less, still more preferably 5 nm or less, and particularly preferably 3 nm or less. Most preferably, it is 1 nm or less. When the in-plane retardation value and the thickness direction retardation value are in such a range, 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 in such a range, 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 expresses positive birefringence as long as it has negative birefringence. If you have a structural unit that expresses positive birefringence and a structural unit that expresses negative birefringence, you can adjust the abundance ratio to control the phase difference of the (meth) acrylic resin film. It is possible to obtain a (meth) acrylic resin film having a low phase difference. As the structural unit that expresses positive birefringence, for example, a structural unit constituting a lactone ring, polycarbonate, polyvinyl alcohol, cellulose acetate, polyester, polyarylate, polyimide, polyolefin, etc., is represented by the general formula (1) described later. Structural units can be mentioned. Examples of the structural unit that expresses negative birefringence include structural units derived from styrene-based monomers, maleimide-based monomers, etc., polymethylmethacrylate structural units, structural units represented by the general formula (3) described later, and the like. Can be mentioned.

As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure or a glutarimide structure is preferably used. A (meth) acrylic resin having a lactone ring structure or a glutarimide structure has excellent heat resistance. More preferably, it is a (meth) acrylic resin having a glutarimide structure. By using a (meth) acrylic resin having a glutarimide structure, as described above, a (meth) acrylic resin film having low moisture permeability and low phase difference and ultraviolet transmittance can be obtained. Examples of the (meth) acrylic resin having a glutarimide structure (hereinafter, also referred to as glutarimide resin) include JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, and JP-A. 2006-328334, 2006-337491, 2006-337492, 2006-337493, 2006-337569, 2007-009182, 2009- It is described in Japanese Patent Application Laid-Open No. 161744. These statements are incorporated herein by reference.

Preferably, the glutarimide resin has 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, (meth)). Also referred to as an acrylic acid ester unit).

式（１）において、Ｒ^１およびＲ^２は、それぞれ独立して、水素または炭素数１〜８のアルキル基であり、Ｒ^３は、水素、炭素数１〜１８のアルキル基、炭素数３〜１２のシクロアルキル基、または炭素数５〜１５の芳香環を含む置換基である。式（２）において、Ｒ^４およびＲ^５は、それぞれ独立して、水素または炭素数１〜８のアルキル基であり、Ｒ^６は、水素、炭素数１〜１８のアルキル基、炭素数３〜１２のシクロアルキル基、または炭素数５〜１５の芳香環を含む置換基である。

In the formula (1), R ¹ and R ² are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R 3 is hydrogen, an alkyl group having 1 to 18 carbon atoms, and ^{3 to 8 carbon atoms.} It is a substituent containing 12 cycloalkyl groups or an aromatic ring having 5 to 15 carbon atoms. In the formula (2), R ⁴ and R ⁵ are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁶ is hydrogen, an alkyl group having 1 to 18 carbon atoms, and 3 to 8 carbon atoms. It is a substituent containing 12 cycloalkyl groups 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), if necessary.

In formula (3), R ⁷ is hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁸ is an aryl group having 6 to 10 carbon atoms.

In the above general formula (1), preferably, R ¹ and R ² are independently hydrogen or methyl groups, and R ³ is hydrogen, methyl group, butyl group, or cyclohexyl group, and more preferably. , R ¹ is a methyl group, R ² is a hydrogen, and R ³ is a methyl group.

The glutarimide resin is a glutarimide unit, may include only a single type, R ¹ in the general formula ^(1), R ^2, and R ³ also include a plurality of different types Good.

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

In the above general formula (2), preferably R ⁴ and R ⁵ are independently hydrogen or methyl groups, R ⁶ is hydrogen or methyl group, and more preferably R ⁴ is hydrogen. , R ⁵ is a methyl group and R ⁶ is a methyl group.

The glutarimide resin is a (meth) acrylic acid ester unit, may include only a single type, R ⁴ in the general formula ^(2), R ^5, and R ⁶ is different types of It may be included.

The glutarimide resin preferably contains styrene, α-methylstyrene and the like, and more preferably styrene, as the aromatic vinyl unit represented by the general formula (3). 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 phase difference can be obtained.

The glutarimide resin is aromatic vinyl unit, may include only a single kind, and may include a plurality of types of R ⁷ and R ⁸ are different.

The content of the glutarimide unit in the glutarimide resin is preferably varied depending on for example the structure of R ³ or the like. The content of the glutarimide unit is preferably 1% by weight to 80% by weight, more preferably 1% by weight to 70% by weight, still more preferably 1% by weight, based on the total structural unit of the glutarimide resin. It is ~ 60% by weight, and particularly preferably 1% by weight to 50% by weight. When the content of the glutarimide unit is in such a range, a low phase difference (meth) acrylic resin film having excellent heat resistance can be obtained.

The content of the aromatic vinyl unit in the glutarimide resin can be appropriately set according to the purpose and desired properties. Depending on the application, the content of the aromatic vinyl unit may be zero. When the aromatic vinyl unit is contained, the content thereof is preferably 10% by weight to 80% by weight, more preferably 20% by weight to 80% by weight, based on the glutarimide unit of the glutarimide resin. It is more preferably 20% by weight to 60% by weight, and particularly preferably 20% by weight to 50% by weight. 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 glutarimide resin may be further copolymerized with other structural units other than the glutarimide unit, the (meth) acrylic acid ester unit, and the aromatic vinyl unit. Other structural units include, for example, a structure composed of nitrile-based monomers such as acrylonitrile and methacrylonitrile, and maleimide-based monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide. The unit is mentioned. These other structural units may be directly copolymerized or graft-copolymerized in the glutarimide resin.

The (meth) acrylic resin film may contain any suitable additive depending on the purpose. Examples of the additive include antioxidants such as hindered phenol-based, phosphorus-based and sulfur-based; stabilizers such as light-resistant stabilizers, ultraviolet absorbers, weather-resistant stabilizers and heat stabilizers; glass fibers, carbon fibers and the like. Reinforcing material; Near infrared absorber; Flame retardant such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide; Antistatic agent such as anionic, cationic, nonionic surfactant; Inorganic pigment, organic pigment, Coloring agents such as dyes; organic fillers and inorganic fillers; resin modifiers; plasticizers; lubricants; phase difference reducing agents and the like. The type, combination, content, etc. of the additives contained can be appropriately set according to the purpose and desired characteristics.

The method for producing the (meth) acrylic resin film is not particularly limited, but for example, a (meth) acrylic resin, an ultraviolet absorber, and if necessary, other polymers and additives, etc. Can be sufficiently mixed by any suitable mixing method to prepare a thermoplastic resin composition in advance, and then film-molded. Alternatively, the (meth) acrylic resin, the ultraviolet absorber, and if necessary, other polymers and additives are made into separate solutions and then mixed to obtain a uniform mixed solution, and then film molding is performed. You may.

To produce the thermoplastic resin composition, the film raw materials are preblended in any suitable mixer, such as an omni mixer, and then the resulting mixture is extruded and kneaded. In this case, the mixer used for extrusion kneading is not particularly limited, and any suitable mixer such as an extruder such as a single-screw extruder or a twin-screw extruder or a pressure kneader may be used. Can be done.

Examples of the film molding method include any suitable film molding method such as a solution casting method (solution casting method), a melt extrusion method, a calender method, and a compression molding method. The melt extrusion method is preferable. Since the melt extrusion method does not use a solvent, it is possible to reduce the manufacturing cost and the load on the global environment and the working environment due to the solvent.

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

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

The (meth) acrylic resin film may be either an unstretched film or a stretched film as long as the desired phase difference can be obtained. When it is a stretched film, it may be either a uniaxially stretched film or a biaxially stretched film. When it is a biaxially stretched film, it may be either a simultaneous biaxially stretched film or a sequential biaxially stretched film.

The stretching temperature is preferably close to the glass transition temperature of the thermoplastic resin composition which is the raw material of the film, and more specifically, preferably (glass transition temperature −30 ° C.) to (glass transition temperature + 30 ° C.). It is preferably in the range of (glass transition temperature −20 ° C.) to (glass transition temperature + 20 ° C.). If the stretching temperature is less than (glass transition temperature −30 ° C.), the haze of the obtained film may increase, or the film may be torn or cracked to obtain a predetermined stretching ratio. On the contrary, when the stretching temperature exceeds (glass transition temperature + 30 ° C.), the thickness unevenness of the obtained film becomes large, and the mechanical properties such as elongation rate, tear propagation strength, and kneading fatigue cannot be sufficiently improved. Tend to do. Further, there is a tendency that troubles such as the film sticking to the roll are likely to occur.

The draw ratio is preferably 1.1 to 3 times, more preferably 1.3 to 2.5 times. When the draw ratio is within such a range, mechanical properties such as film elongation, tear propagation strength, and kneading fatigue resistance can be significantly improved. As a result, it is possible to produce a film having small thickness unevenness, substantially zero birefringence (and therefore small phase difference), and low haze.

The (meth) acrylic resin film can be heat-treated (annealed) or the like after the stretching treatment in order to stabilize its optical isotropic property and mechanical properties. As the heat treatment conditions, any suitable conditions may be adopted.

The photoelastic coefficient of the (meth) acrylic resin film is preferably -3 to -100 × 10 ^-13 Pa ^-1 , more preferably -5 to −70 × 10 ^-13 Pa ^-1 , and even more preferably. It is -15 to -50 × 10 ^-13 Pa ^-1 . The photoelastic coefficient can be measured by the method described above.

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

When the protective film is laminated on both sides of the polarizer, the same film as described above may be laminated on both sides, or another resin film may be used. For example, an olefin resin film, a polyester resin film, and a cellulosic resin film are preferably used.

Examples of the chain polyolefin resin include polyethylene resin (polyethylene resin which is a homopolymer of ethylene and a copolymer mainly composed of ethylene) and polypropylene resin (polypropylene resin which is a homopolymer of propylene and propylene as a main component). In addition to homopolymers of chain olefins such as (copolymers), copolymers composed of two or more kinds of chain olefins can be mentioned.

Cyclic polyolefin resin is a general term for resins that are polymerized using cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin is mentioned. Specific examples of the cyclic polyolefin resin include an open (co) polymer of a cyclic olefin, an addition polymer of a cyclic olefin, and a copolymer of a cyclic olefin and a chain olefin such as ethylene and propylene (typically). Is a random copolymer), a graft polymer obtained by modifying these with an unsaturated carboxylic acid or a derivative thereof, and a hydride thereof. Among them, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer is preferably used as the cyclic olefin.

The polyester-based resin is a resin having an ester bond, excluding the following cellulose ester-based resin, and is generally composed of a polyvalent carboxylic acid or a polycondensate of a derivative thereof and a polyhydric alcohol. As the polyvalent carboxylic acid or a derivative thereof, a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylic acid. As the polyhydric alcohol, a divalent diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A typical example of the polyester resin is polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

Cellulose ester-based resins are esters of cellulose and fatty acids. Specific examples of the cellulosic ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. In addition, these copolymers and those in which a part of the hydroxyl group is modified with another substituent can also be mentioned. Among these, cellulose triacetate (triacetyl cellulose) is particularly preferable.

The thickness of the protective film is usually 1 to 100 μm, but is preferably 5 to 60 μm, more preferably 10 to 55 μm, and even more preferably 15 to 40 μm from the viewpoint of strength, handleability, and the like.

As described above, the protective film has a hard coat layer, an antiglare layer, a light diffusing layer, an antireflection layer, a low refractive index layer, an antistatic layer, and an antifouling layer on the outer surface (the surface opposite to the polarizer). It may be provided with a surface treatment layer (coating layer) such as a layer. The thickness of the protective film includes the thickness of the surface treatment layer.

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

Examples of the water-based adhesive include an adhesive composed of a polyvinyl alcohol-based resin aqueous solution, a water-based two-component urethane-based emulsion adhesive, and the like. Of these, a water-based adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin is preferably used. The polyvinyl alcohol-based resin includes a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable therewith. A polyvinyl alcohol-based copolymer obtained by saponifying the polymer, or a modified polyvinyl alcohol-based polymer in which the hydroxyl groups thereof are partially modified can be used. The water-based adhesive may contain a cross-linking agent such as an aldehyde compound (glioxal or the like), an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.

When a water-based adhesive is used, it is preferable to carry out a drying step for removing water contained in the water-based adhesive after the polarizer and the protective film are bonded together. After the drying step, a curing step of curing at a temperature of, for example, 20 to 45 ° C. may be provided.

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

The curable compound can 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 one or more epoxy groups in the molecule) and an oxetane compound (one or two or more oxetane rings in the molecule). Compounds), or a combination thereof. Examples of the radically polymerizable curable compound include a (meth) acrylic compound (a compound having one or more (meth) acryloyloxy groups in the molecule) and a radically polymerizable double bond. Other vinyl compounds or combinations thereof can be mentioned. A cationically polymerizable curable compound and a 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 the curing reaction of the curable compound.

When the polarizer and the protective film are bonded, a surface activation treatment may be applied to at least one of these bonding surfaces in order to enhance the adhesiveness. Surface activation treatment includes dry treatment such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionization active ray treatment (ultraviolet ray treatment, electron beam treatment, etc.). Wet treatments such as ultrasonic treatment using a solvent such as water or acetone, saponification treatment, and anchor coating treatment can be mentioned. These surface activation treatments may be performed alone or in combination of two or more.

When the protective films are bonded to both sides of the polarizer, the adhesive for bonding these protective films may be the same type of adhesive or different types of adhesives.
Further, the above-mentioned bonding method using an adhesive or an adhesive can be used not only for bonding a polarizer and a protective film but also for bonding other optical functional layers contained in the optical laminate of the present invention. Good. For example, when the optical laminate has two or more layers of retardation films, it can be used for bonding the retardation films to each other.

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

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

The pressure-sensitive adhesive composition may contain only the above-mentioned base polymer, but usually further contains a cross-linking agent. The cross-linking agent is a divalent or higher metal ion that forms a carboxylic acid metal salt with a carboxyl group; a polyamine compound that forms an amide bond with a carboxyl group; poly. Epoxy compounds and polyols that form an ester bond with a carboxyl group; polyisocyanate compounds that form an amide bond with a carboxyl group are exemplified. Of these, polyisocyanate compounds are preferable.

The pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition have been described as examples of being used for the pressure-sensitive adhesive layer 12 used for bonding the optical laminate of the present invention and the organic EL display element, but the present invention is not limited thereto. For example, it may be used for bonding the optical laminate of the present invention to another optical functional layer, or for bonding optical functional layers constituting in the optical laminate.

<Front plate>
The front plate is arranged on the visible side of the polarizing plate. The front plate can be laminated on the polarizing plate via the adhesive layer. Examples of the adhesive layer include the above-mentioned adhesive layer and adhesive layer. As shown in FIG. 2, the front plate 5 can be laminated on the polarizing plate 3 via an adhesive layer (not shown). As shown in FIG. 2, the front plate 5 may be formed with a light-shielding pattern 6.

Examples of the front plate include those having a hard coat layer on at least one surface of glass or a resin film. As the glass, for example, highly transparent glass or tempered glass can be used. Especially when a thin transparent surface material is used, chemically strengthened glass is preferable. The thickness of the glass can be, for example, 100 μm to 5 mm.

The front plate, which includes a hard coat layer on at least one surface of the resin film, can have a flexible property rather than being rigid like existing glass. The thickness of the hard coat layer is not particularly limited and may be, for example, 5 to 100 μm.

Examples of the resin film include cycloolefin derivatives having a unit of a monomer containing cycloolefin such as norbornene or polycyclic norbornene-based monomer, and cellulose (diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl ester cellulose). , Propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose) ethylene-vinyl acetate copolymer, polycycloolefin, polyester, polystyrene, polyamide, polyetherimide, polyacrylic, polyimide, polyamideimide, polyethersulfone, polysulfone, polyethylene, Polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate , Polyethylene, a film made of a polymer such as epoxy. As the resin film, an unstretched uniaxial or biaxially stretched film can be used. Each of these polymers can be used alone or in combination of two or more. As the resin film, a polyamideimide film or a polyimide film having excellent transparency and heat resistance, a uniaxial or biaxially stretched polyester film, a cycloolefin derivative film having excellent transparency and heat resistance and capable of adapting to a large size of the film. , Polymethylmethacrylate films and triacetylcellulose and isobutylester cellulose films that are transparent and not optically anisotropic are preferred. The thickness of the resin film may be 5 to 200 μm, preferably 20 to 100 μm.

The hard coat layer can be formed by curing a hard coat composition containing a reactive material that is irradiated with light or heat energy to form a crosslinked structure. The hard coat layer can be formed by curing a hard coat composition containing a photocurable (meth) acrylate monomer, or an oligomer and a photocurable epoxy monomer, or an oligomer at the same time. The photocurable (meth) acrylate monomer may contain one or more selected from the group composed of epoxy (meth) acrylate, urethane (meth) acrylate and polyester (meth) acrylate. The epoxy (meth) acrylate can be obtained by reacting an epoxy compound with a carboxylic acid having a (meth) acryloyl group.

The hard coat composition may further comprise one or more selected from the group consisting of solvents, photoinitiators and additives. Additives can include one or more selected from the group consisting of inorganic nanoparticles, leveling agents and stabilizers, and other components commonly used in the art, such as anti. Excipients, UV absorbers, surfactants, lubricants, antifouling agents and the like can be further included.

<Shading pattern>
The shading pattern can be provided as at least part of the front plate or the bezel or housing of the display device to which the front plate is applied. The light-shielding pattern can be formed on the display element side of the front plate. The shading pattern can hide each wiring of the display device so that it cannot be seen by the user. The color and / or material of the light-shielding pattern is not particularly limited, and can be formed of a resin substance having various colors such as black, white, and gold. In one embodiment, the thickness of the shading pattern may be 2 μm to 50 μm, preferably 4 μm to 30 μm, and more preferably 6 μm to 15 μm. Further, in order to suppress the mixing of air bubbles due to the step between the light-shielding pattern and the display unit and the visibility of the boundary portion, the light-shielding pattern can be shaped.

<Touch sensor>
The touch sensor is used as an input means. As the touch sensor, various types such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and a capacitance method have been proposed, and any method may be used. Of these, the capacitance method is preferable. The capacitive touch sensor is divided into an active region and an inactive region located outside the active region. The active area is an area corresponding to the area (display unit) on which the screen is displayed on the display panel, the area where the user's touch is sensed, and the inactive area is the area where the screen is not displayed on the image display device ( This is the area corresponding to the non-display part). The touch sensor shall include the substrate; the sensing pattern formed in the active region of the substrate; the sensing pattern formed in the inactive region of the substrate and each sensing line for connecting to an external drive circuit via the pad section. Can be done. As the substrate, the same material as glass or the resin film constituting the above-mentioned front plate can be used. The substrate of the touch sensor preferably has a toughness of 2,000 MPa% or more from the viewpoint of suppressing cracks in the touch sensor. More preferably, the toughness may be 2,000 MPa% or more and 30,000 MPa% or less.

The sensing pattern can include a first pattern formed in the first direction and a second pattern formed in the 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 each pattern must be electrically connected in order to sense the point of being touched. The first pattern is a form in which the unit patterns are connected to each other via a joint, but the second pattern has a structure in which the unit patterns are separated from each other into an island form, so that the second pattern is electrically connected. A separate bridge electrode is required for connection. A well-known transparent electrode material can be applied to the sensing pattern. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium tin oxide oxide (IZTO), cadmium tin oxide (CTO), PEDOT (poly (3,4-). Ethylenedioxythiophene)), carbon nanotubes (CNTs), graphenes, metal wires and the like can be mentioned, and these can be used alone or in admixture of two or more. ITO can be preferably used. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, telenium, and chromium. These can be used alone or in combination of two or more.

The bridge electrode can be formed on the upper part of the insulating layer via the insulating layer on the upper part of the sensing pattern, the bridge electrode is formed on the substrate, and the insulating layer and the sensing pattern can be formed on the bridge electrode. The bridge electrode can also be made of the same material as the sensing pattern and is made of metals such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium or alloys of two or more of these. You can also do it. Since the first pattern and the second pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer can be formed only between the joint of the first pattern and the bridge electrode, or can be formed in a layer structure covering the sensing pattern. In the latter case, the bridge electrode can connect the second pattern through a contact hole formed in the insulating layer.
The touch sensor has a difference in transmittance between a patterned region in which a pattern is formed and a non-patterned region in which a pattern is not formed, specifically, a difference in light transmittance induced by a difference in refractive index in these regions. An optical control layer can be further included between the substrate and the electrode as a means for appropriately compensating for the above, and the optical control layer can include an inorganic insulating material or an organic insulating material. The optical control layer can be formed by coating a photocurable composition containing a photocurable organic binder and a solvent on a substrate. The photocurable composition can further contain inorganic particles. Inorganic particles can increase the refractive index of the optical control layer.

The photocurable organic binder can contain, for example, a copolymer of each monomer such as an acrylate-based monomer, a styrene-based monomer, and a carboxylic acid-based monomer. The photocurable organic binder may be, for example, a copolymer containing different repeating units such as an epoxy group-containing repeating unit, an acrylate repeating unit, and a carboxylic acid repeating unit. The inorganic particles can include, for example, zirconia particles, titania particles, alumina particles and the like. The photocuring composition may further contain each additive such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

<Manufacturing method of optical laminate>
A method for manufacturing the optical laminate will be described by taking the optical laminate shown in FIGS. 1 (a) to 1 (c) as an example.
The optical laminate 100 (FIG. 1A) can be manufactured, for example, as follows. The alignment layer 11 is formed on the base material, and a coating liquid containing a polymerizable liquid crystal compound is applied onto the alignment layer 11. With the polymerizable liquid crystal compound oriented, heat treatment or irradiation with active energy rays is performed to cure the polymerizable liquid crystal compound. After the polymerizable liquid crystal compound is cured to form the retardation layer 10, the base material is peeled off, and the pressure-sensitive adhesive layer 12 formed on the release film is laminated on the peeled surface of the alignment layer 11.
In the case of the optical laminate 101 shown in FIG. 1 (b), the same is true up to the point where the optical laminate 100 shown in FIG. 1 (a) and the retardation layer 10 are formed. The retardation layer 10 and the second retardation film are laminated via the adhesive layer 13. When the optical laminate 100 and the retardation layer 10 are elongated, the respective members may be bonded to each other by roll-to-roll via the adhesive layer 13. After laminating the optical laminate 100 and the second retardation film, the base material is peeled off, and the pressure-sensitive adhesive layer 12 formed on the release film is laminated on the peeled surface of the alignment layer 11.
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 polarizing element and a protective film via an adhesive layer. The protective film may be laminated on at least one surface of the polarizer. The polarizing plate may be manufactured by preparing long members, laminating the respective members by roll-to-roll, and then cutting them into a predetermined shape, or cutting each member into a predetermined shape. After that, they may be pasted together. After the protective film is attached to the polarizer, a heating step or a humidity control step may be provided. The retardation film is the same as the optical laminate 101 of FIG. 1 (b) up to the point where the second retardation film is laminated, and is on the side opposite to the adhesive layer 13 of the second retardation film. The surface is laminated with the polarizing plate 3 via an adhesive layer or an adhesive layer. When the polarizing plate 3 and the optical laminate 101 have a long shape, the respective members may be bonded by roll-to-roll. After laminating the polarizing plate 3, the base material is peeled off, and the pressure-sensitive adhesive layer 12 formed on the release film is laminated on the peeled surface of the alignment layer 11.

Then, the organic EL display device can be manufactured by peeling off the release film laminated on the pressure-sensitive adhesive layer 12 and laminating the optical laminate and the organic EL display element via the pressure-sensitive adhesive layer 12.

<Use>
The optical laminate of the present invention can be used in various display devices. The 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 inorganic EL) display device, an electron emission display device (for example, an electric field emission display device (also referred to as FED), and a surface electric field emission display. Device (also called SED)), electronic paper (display device using electronic ink or electrophoretic element, plasma display device, projection type display device (for example, grating light valve (GLV) display device, digital micromirror device (DMD)) (Also referred to as), a piezoelectric ceramic display, and the like. The liquid crystal display device includes any of a transmissive liquid crystal display device, a transflective liquid crystal display device, and the like. These display devices include a two-dimensional image. It may be a display device for displaying a three-dimensional image, or a three-dimensional display device for displaying a three-dimensional image. The optical laminate can be particularly effectively used for an organic EL display device or an inorganic EL display device. ..

In FIG. 2, the organic EL display device 103 has a layer structure in which an optical laminate is laminated on the organic EL display element 4 via an adhesive layer 12 laminated on the retardation film 1.

Further, the display device can be a flexible display device, or can 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 arranged on the visual side with respect to the organic EL display element, and is configured to be bendable. Bendable means that it can be bent without causing cracks and breaks. 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 plate and a touch sensor.

As a specific optical laminate, the front plate, the polarizing plate, the retardation film, and the touch sensor are laminated in this order from the visual side, or the front plate, the touch sensor, the polarizing plate, and the retardation film are laminated in this order from the visual side. Examples are mentioned. The presence of the polarizing plate on the visual side of the touch sensor is preferable because the pattern of the touch sensor is less likely to be visually recognized and the visibility of the displayed image is improved. Each member can be laminated using an adhesive, an adhesive, or the like. Further, a light-shielding pattern formed on at least one surface of any layer of the front plate, the polarizing plate, the retardation film, and the touch sensor can be provided.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples. In the examples, the part indicating the content or the amount used and% are based on weight unless otherwise specified. The physical properties of each of the following examples were measured by the following methods.

(1) Measurement of film thickness Measurement was performed using a digital micrometer MH-15M manufactured by Nikon Corporation.

(Measurement of puncture elastic modulus)
A fragment of 40 mm in length × 40 mm in width was cut out from the first retardation film with a base film obtained in Examples and Comparative Examples. In addition, a glued mount having a length of 40 mm and a width of 40 mm was prepared. This glued mount is cut out in a square having a central portion of 30 mm × 30 mm. After the laminate is attached to the glued mount so that the surface of the retardation layer 1 is in contact with the glue on the glued mount, the base material is peeled off from the first retardation film to prepare a sample for puncture test. Made.

The puncture elastic modulus was measured as follows. The needle was attached to the "NDG5 piercing tester" manufactured by Kato Tech Co., Ltd. The needle is pierced perpendicularly to the main surface (surface of the retardation layer 1) of the piercing test sample, and the stress F (g) immediately before the piercing test sample breaks and the strain amount S (mm) at that time. ) Was calculated, and the puncture elastic modulus (g / mm) was calculated by stress F (g) / strain amount S (mm). As the needle, a needle having a tip diameter of 1 mmφ and 0.5R was used. The speed at which the needle was pierced was 0.33 cm / sec. Table 1 shows the puncture elastic modulus of the retardation film 1. The measurement was performed in a room temperature environment with a temperature of 23 ° C. and a humidity of 50%.

(3) Abrasion resistance evaluation (steel wool hardness)
The wear resistance of the surface of the alignment layer of the retardation film was evaluated by a steel wool test.
A steel wool tester (manufactured by Daiei Seiki Co., Ltd.) was used to carry out each operation on a cyclic polyolefin resin (COP) substrate (thickness 20 μm) in which a wiper for a clean room (BEMCOT AZ-8 manufactured by Asahi Kasei Co., Ltd.) was placed on a glass plate. For example, the surface of the alignment layer formed by the same method as in the comparative example was brought into contact with a load of 500 g, a four-reciprocating wear test was performed at a speed of 40 r / min, and the number of scratches visually generated under a fluorescent lamp was counted. It was.

(4) Abrasion resistance evaluation (pencil hardness evaluation)
The surface hardness of the surface of the alignment layer of the retardation film was evaluated by a pencil hardness test.
Cyclic polyolefin resin (COP) base material (thickness 20 μm) in which a pencil for testing (Unistar manufactured by Mitsubishi Pencil Co., Ltd.) is placed on a glass plate with a pencil hardness tester (No. 535-M1 manufactured by Yasuda Seiki Seisakusho). The surface of the alignment layer formed by the same method as in each of the examples and comparative examples was brought into contact with the surface of the alignment layer at an angle of 45 degrees with a load of 500 g, and a hardness test was performed at a speed of 0.5 mm / sec, and visually observed under a fluorescent lamp. The presence or absence of scratches that occurred was counted. Of the five tests, one or less was confirmed to have a hardness that would cause scratches.

[Example 1]
(Preparation of the first retardation film 1)
As a composition for forming an oriented layer,
Polyethylene glycol di (meth) acrylate (A-600 manufactured by Shin Nakamura Chemical Industry Co., Ltd.) 10.0 parts by weight and
Trimethylolpropane triacrylate (A-TMPT manufactured by Shin Nakamura Chemical Industry Co., Ltd.) 10.0 parts by weight and
10.0 parts by weight of 1,6-hexanediol di (meth) acrylate (A-HD-N manufactured by Shin Nakamura Chemical Industry Co., Ltd.)
1.50 parts by weight of Irgacure 907 (Irg-907 manufactured by BASF) as a photopolymerization initiator.
Solvent Methyl ethyl ketone Dissolved in 70.0 parts by weight to prepare a coating solution for forming an orientation layer.

A long cyclic olefin resin film (manufactured by Nippon Zeon Corporation) with a thickness of 20 μm was prepared as a base film, and the obtained coating liquid for forming an alignment layer was applied to one side of the base film with a bar coater. It was applied.
After the coating layer after coating is heat-treated at a temperature of 80 ° C. for 60 seconds, it is ^{irradiated with ultraviolet rays (UVB) at 220 mJ / cm 2} to polymerize and cure the composition for forming an orientation layer, and then on the substrate film. An oriented layer 1 having a thickness of 3.5 μm was formed on the surface.

20.0 parts by weight of a photopolymerizable nematic liquid crystal compound (RMM28B manufactured by Merck) and 1.0 part by weight of Irgacure 907 (Irg-907 manufactured by BASF) as a photopolymerization initiator as a composition for forming a retardation. , The solvent was dissolved in 80.0 parts by weight of propylene glycol monomethyl ether acetate to prepare a coating solution for forming a retardation layer.
A coating liquid for forming a retardation layer was applied onto the previously obtained alignment layer, and the coating layer was heat-treated at a temperature of 80 ° C. for 60 seconds. Then, it was irradiated with ultraviolet rays (UVB) at 220 mJ / cm ² to polymerize and cure the composition for forming a retardation layer to form a retardation layer 1 having a thickness of 0.7 μm on the alignment layer. In this way, a first retardation film 1 composed of an alignment layer 1 and a retardation layer 1 was obtained on the base film. The first retardation film 1 showed a retardation in the thickness direction. Further, it was confirmed that the first retardation film 1 can be peeled off from the base film.

(Preparation of polarizing plate)
A 20 μm-thick polyvinyl alcohol film (average degree of polymerization of about 2400, saponification degree of 99.9 mol% or more) was uniaxially stretched about 4 times by dry stretching, and further uniaxially stretched to pure water at 40 ° C. while maintaining a tense state. After immersing for 40 seconds, the dyeing treatment was performed by immersing in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.052 / 5.7 / 100 at 28 ° C. for 30 seconds. Then, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 11.0 / 6.2 / 100 at 70 ° C. for 120 seconds. Subsequently, after washing with pure water at 8 ° C. for 15 seconds and then drying at 60 ° C. for 50 seconds and then at 75 ° C. for 20 seconds while holding the film at a tension of 300 N, iodine is adsorbed and oriented on the polyvinyl alcohol film. An absorption type polarizer film having a thickness of 8 μm was obtained. A water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is applied to both sides of the obtained polarizer film, and a protective film (Zeon COP film Zeonoa ZF14) is applied to one side of the polarizer film and a protective film (Fuji film) is applied to the other side. TAC film Fujitac TJ25) was laminated to obtain a polarizing plate with a double-sided protective film.

(Preparation of optical laminate)
One of the release films of the sheet-like adhesive (thickness 25 μm, manufactured by Lintec Corporation, P-3132) with a double-sided release film is peeled off, and the obtained polarizing plate is bonded to the TAC film side surface of the obtained polarizing plate via an adhesive layering agent. The release film on the other side of the sheet-like pressure-sensitive adhesive was peeled off, and the pressure-sensitive adhesive layer was laminated on the surface of the polarizing plate on the TAC film side. The surface of the first retardation film on the retardation layer 1 side and the polarizing plate were bonded to each other via the laminated pressure-sensitive adhesive layer, and then the base film was peeled off from the first retardation film 1. Further, after peeling off one of the release films of the sheet-like pressure-sensitive adhesive with the double-sided release film, the base film of the first retardation film 1 is bonded to the peeled surface via the pressure-sensitive adhesive layer to form a laminated structure. An optical laminate as a polarizing plate / adhesive layer / first retardation film 1 / adhesive layer / release film was obtained.

[Examples 2 and 3, Comparative Examples 1 and 2]
Examples 2 and 3 were carried out in the same manner as in Example 1 except that the composition for forming the alignment layer 1 and the retardation layer 1 constituting the first retardation film was changed in the compounding ratio and thickness in Table 1. , The optical laminates of Comparative Examples 1 and 2 were produced. Further, the first retardation films obtained in Examples 2 and 3 and Comparative Examples 1 and 2 showed a retardation in the thickness direction.

[Example 4]
A coating liquid for forming an orientation layer was prepared using the composition for forming an alignment layer as the material and compounding ratio in Table 1, and the coating layer of the coating liquid was heat-treated at a temperature of 100 ° C. for 120 seconds to be cured.
An optical laminate was produced in the same manner as in Example 1 except for the above. Further, the first retardation film obtained in Example 4 showed a retardation in the thickness direction.

[Example 5]
[Preparation of the first retardation film 2]
5.0 parts by weight (weight average molecular weight: 30,000) of the photo-oriented material having the following structure and 95.0 parts by weight of cyclopentanone (solvent) are mixed, and the obtained mixture is stirred at 80 ° C. for 1 hour. As a result, a composition for forming an alignment film was obtained.

0.1 part by weight of the leveling agent (F-556; manufactured by DIC) with respect to 10 parts by weight of the mixture obtained by mixing the polymerizable liquid crystal compound A and the polymerizable liquid crystal compound B shown below at a mass ratio of 9: 1. , And the polymerization initiator 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butane-1-one ("Irgacure 369 (Irg369)", manufactured by BASF Japan Co., Ltd.) by 0.6 parts by mass. Added.

Further, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration was 13%, and the mixture was stirred at 80 ° C. for 1 hour to obtain a composition for forming a liquid crystal cured film.

The polymerizable liquid crystal compound A was produced by the method described in JP-A-2010-31223. Further, the polymerizable liquid crystal compound B was produced according to the method described in JP-A-2009-173893. The molecular structure of each is shown below.

(Polymerizable liquid crystal compound A)

(Polymerizable liquid crystal compound B)

[Manufacture of a laminate consisting of a base material, an alignment film, and a layer obtained by curing a polymerizable liquid crystal compound]
Corona treatment was carried out on a 50 μm-thick cycloolefin-based film [trade name “ZF-14-50” manufactured by Nippon Zeon Corporation] as a base material. The composition for forming an alignment film was applied to the surface treated with corona with a bar coater. The coating film was dried at 80 ° C. for 1 minute. The dried coating film was irradiated with polarized UV at an axial angle of 45 ° using a polarized UV irradiation device [trade name “SPOT CURE SP-9” of Ushio Electric Co., Ltd.] to obtain an alignment film. The irradiation of polarized UV was performed so that the integrated light intensity at a wavelength of 313 nm was 100 mJ / cm ^2.

Subsequently, the composition for forming a liquid crystal cured film was applied onto the alignment film using a bar coater. The coating film was dried at 120 ° C. for 1 minute. The dried coating film was irradiated with ultraviolet rays using a high-pressure mercury lamp [trade name of Ushio, Inc.: "Unicure VB-15201BY-A"]. The ultraviolet irradiation step was performed in a nitrogen atmosphere so that the integrated light intensity at a wavelength of 365 nm was 250 mJ / cm ^2. Immediately after the irradiation, as a cooling step, the cured film was placed in an oven set at 5 ° C. for 20 seconds. Immediately after taking out the oven, the ultraviolet irradiation step and the cooling step were carried out again to obtain a first retardation film 2 composed of an alignment film and a layer on which the polymerizable liquid crystal compound was cured on the substrate. The first retardation film 2 showed a retardation in the in-plane direction. The obtained first retardation film 2 was used in place of the first retardation film 1 to obtain an optical laminate in the same manner as in Example 1.

[Example 6]
A first retardation film is produced by the same method as in Comparative Example 1, and when the optical laminate is produced, the first retardation film is peeled off between the alignment layer 1 and the retardation layer 1, and the first retardation film is separated from the retardation layer 1. The optical laminate of Example 6 was produced by the same method as in Example 1 except that only the film was used.

The release films of the optical laminates obtained in Examples 1 to 6 and Comparative Examples 1 and 2 were peeled off and bonded to a glass plate via an exposed adhesive layer to obtain the state shown in FIG. Then, the thermal shock resistance test was carried out by the following method.
The pen tip of the Eriksen pen (model number 318 manufactured by Eriksen Co., Ltd.) set to a load of 10 N was pressed against the surface of the polarizing plate in the optical laminate opposite to the glass plate side as the starting point. Similar starting points were provided at equal intervals at two other locations (three locations in total). Then, several cycles of a thermal shock resistance test (ESPEC CORP. Product name: TSA-303EL-W) were carried out with one cycle of -20 ° C for 30 minutes and 60 ° C for 30 minutes. Before the thermal shock resistance test, the length of cracks generated from each starting point where the Elixen pen was pressed against the surface of the polarizing plate in the optical laminate was measured, and the average value of the crack measurement results at the three starting points was calculated as the crack length. It was set to (mm).

The puncture elastic modulus, film thickness, abrasion resistance evaluation (steel wool, pencil hardness) of the first retardation film obtained in Examples 1 to 6 and Comparative Examples 1 and 2 and the thermal impact test of the optical laminate were performed. The results are shown in Table 2. The puncture elastic modulus of the first retardation films of Examples 1 to 5 and Comparative Examples 1 and 2 was determined by first peeling the base film from the laminate of the first retardation film and the base film. The measurement was performed by pressing the piercing jig from the retardation layer 1 side against the retardation film (phase difference layer 1 + alignment layer 1). As the first retardation film of Example 6, the base film and the alignment layer 1 were peeled off from the retardation layer 1, and the results of measurement with respect to the first retardation film (only the retardation layer 1) were shown. Further, the wear resistance evaluation was carried out for the oriented layers of Examples 1 and 2 and Comparative Example 1.

により算出された値Ｎ１である。 Table 3, the examples and the thickness L _AL alignment layer in the phase difference film obtained in Comparative Example, the content of units derived from the polymerizable compound i in the resin constituting the orientation layer Cwi, the polymerizable The molecular weight Mi and the number of functional groups Ni of the compound i are shown. The amount of polymerizable groups in the oriented layer is calculated by the calculation formula (A-1).

It is a value N1 calculated by.

により算出される値Ｎ２である。
そして表３に、前記の計算式（Ａ）により算出された重合性基量Ｎを併せて示す。 Further, in Table 3, and the thickness L _LC of the retardation layer in the phase difference film obtained in each of Examples and Comparative Examples, the content Cwj of units derived from the polymerizable liquid crystal compound j constituting the retardation layer , The molecular weight Mj and the number of functional groups Nj of the polymerizable liquid crystal compound j are shown. The amount of polymerizable groups in the retardation layer is calculated by the calculation formula (A-2).

It is a value N2 calculated by.
Table 3 also shows the amount of polymerizable groups N calculated by the above formula (A).

According to the present invention, it is useful because it is possible to provide an optical laminate provided with a retardation film, which can suppress the occurrence of cracks even in an environment subject to a sudden temperature change.

1 First retardation film (phase difference film)
2 Second retardation film 3 Polarizing plate 4 Organic EL display element 5 Front plate 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 laminate 103 Organic EL display device

Claims (6)

An optical laminate having a retardation film
The retardation film is
When the tip of the piercing jig is pressed perpendicularly to the film surface and breakage occurs,
The puncture elastic modulus calculated by the following equation (1) using the stress F (g) applied to the retardation film from the tip of the puncture jig and the strain amount S (mm) of the retardation film. An optical laminate characterized by being 50 g / mm or less.

(1) Puncture elastic modulus (g / mm) = F (g) / S (mm)
The optical laminate according to claim 1, wherein the retardation film includes a retardation layer in which a polymerizable liquid crystal compound is cured. The optical laminate according to claim 2, wherein the retardation film further includes an alignment layer. The optical laminate according to claim 2 or 3, wherein the retardation layer has vertical orientation. The optical laminate according to any one of claims 1 to 4, further comprising a polarizing plate. A display device in which the optical laminate according to any one of claims 1 to 5 is laminated on a display element.

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