JP7422048B2 - optical laminate - Google Patents

Description

The present invention relates to an optical laminate.

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

As retardation films for image display devices such as organic EL display devices, those made by stretching conventional resin films and those made from liquid crystal compounds are being considered, and there is a demand for thinner image display devices. As the strength increases, retardation films and optical laminates including the same are also required to be made thinner (see, for example, Patent Document 1). In an optical laminate having such a retardation film, cracks may occur starting from the retardation film due to expansion and contraction due to temperature changes. In particular, cracks are likely to occur when a sudden temperature change (thermal shock) is applied. When such cracks occur, not only the durability of the optical laminate but also the visibility of the display device may deteriorate.

Japanese Patent Application Publication No. 2017-102286

The purpose of the present invention is to solve the above-mentioned problems, and to provide an optical laminate having a retardation film, which can suppress the occurrence of cracks even in an environment subject to sudden temperature changes (thermal shock). It is to provide.

The present invention provides optical laminates shown in [1] to [5] below.
[1] An optical laminate having a retardation film, wherein the retardation film is formed by pressing the tip of the stabbing jig perpendicularly against the film surface, and when breakage occurs, the retardation film is separated from the tip of the stabbing jig. The puncture elastic modulus calculated by the following formula (1) using the stress F (g) applied to the retardation film and the amount of strain S (mm) of the retardation film is 50 g / mm or less. An optical laminate featuring:

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

[2] The optical laminate according to [1], wherein the retardation film includes a retardation layer made of a cured polymerizable liquid crystal compound.
[3] The optical laminate according to [2], wherein the retardation film further includes an alignment layer.
[4] The optical laminate according to [2] or [3], in which the retardation layer has vertical alignment.
[5] The optical laminate according to any one of [1] to [4], further comprising a polarizing plate.
The present invention also provides a display device shown in [6] below.
[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, which can suppress the occurrence of cracks even in an environment subject to rapid temperature changes.

(a) to (c) are examples of schematic cross-sectional views showing the layer structure of the optical laminate of the present invention. 1 is an example of a schematic cross-sectional view showing a layer structure of an organic EL display device. 2 is a schematic cross-sectional view showing the layer structure during a thermal shock test using the optical laminates produced in Examples 1 to 6 and Comparative Examples 1 and 2. FIG.

(Definition of terms and symbols)
Definitions of terms and symbols used herein are as follows.
(1) Puncture elastic modulus When the tip of the piercing jig is pressed perpendicularly to the film surface and breakage occurs, stress F (g) applied to the film from the tip of the piercing jig and the through hole Alternatively, it is a physical property value of a film defined using the amount of strain S (mm) generated in the film before breakage occurs, and is expressed as a proportionality constant between stress F and strain S (stress F/strain S).
The piercing modulus of elasticity can be measured using a compression testing machine equipped with a load cell. Examples of compression testing machines include the piercing testing machine "NDG5" manufactured by Kato Tech Co., Ltd., and the handy compression testing machine "KES-". G5" and Shimadzu Corporation's small tabletop testing machine "EZ Test". From the stress-strain curve obtained using such a compression tester, it is possible to measure the stress applied to the film at the time of breakage and the amount of strain that has occurred in the film up to that point.
Breaks that occur in the film when pressed by the stabbing jig include cases where a through hole is created in the film by the jig tip.
(2) Orientation layer This refers to a layer that has the ability to regulate the direction of the molecular axis of the polymerizable liquid crystal compound forming the retardation layer so that it has desired retardation characteristics. A layer (retardation layer) in which a polymerizable liquid crystal compound is cured is formed on a substrate via an alignment layer. Examples of the alignment layer include an alignment layer containing an alignment polymer, a photo alignment film, and a groove alignment layer in which a concavo-convex pattern or a plurality of grooves are formed on the surface for alignment.
(3) Vertical alignment A state in which the direction of the molecular axis of the polymerizable liquid crystal compound forming the retardation layer is approximately perpendicular to the lamination plane of each layer constituting the optical laminate. A typical example of a retardation layer exhibiting vertical alignment is a positive C layer.
(4) Refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (that is, the slow axis direction), "ny" is the in-plane direction perpendicular to the slow axis, and "nz" is the refractive index in the thickness direction. It is the 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 wavelength λ (nm). Re[λ] is determined by Re[λ]=(nx−ny)×d, where d (nm) is the thickness of the film.
(6) Retardation value in the thickness direction The in-plane retardation value (Rth[λ]) refers to the retardation value in the thickness direction of the film at 23° C. and wavelength λ (nm). Rth[λ] is determined 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 includes a retardation film, and the retardation film has a puncture elastic modulus of 50 g/mm or less. Further, the retardation film has a retardation layer. The retardation layer preferably has a layer made of a composition containing a polymerizable liquid crystal compound. Specifically, the layer composed of a composition containing a polymerizable liquid crystal compound means a layer in which the polymerizable liquid crystal compound is cured. In this specification, a layer that provides a retardation of λ/2, a layer that provides a retardation of λ/4 (positive A layer), a positive C layer, etc. may be collectively referred to as a retardation layer. Furthermore, the retardation film may include an alignment layer described below.

Hereinafter, an example of the layer structure of the optical laminate of the present invention will be explained with reference to FIG. The optical laminate 100 shown in FIG. 1A has a layer structure in which a retardation layer 10 is laminated on one surface of an alignment layer 11, and an adhesive layer 12 is provided on the other surface of the alignment layer 11. The adhesive layer 12 can be an adhesive layer for bonding to an organic EL display element or the like. In this optical laminate 100, the retardation film 1 is composed of a retardation layer 10 and an alignment layer 11.

The optical laminate 101 shown in FIG. 1(b) has a second retardation film attached to the surface of the retardation layer 10 of FIG. 1(a) opposite to the orientation layer 11 via an adhesive layer 13. It has a layered structure in which 2 layers are laminated. The adhesive layer 12 can be an adhesive layer for bonding to an organic EL display element or the like, as in FIG. 1(a). In this 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 a pressure-sensitive adhesive on the surface of the second retardation film 2 in FIG. 1(b) opposite to the first retardation film 1. It has a layered structure in which polarizing plates 3 are laminated via layers. Here, an adhesive layer or a pressure-sensitive adhesive layer for bonding the second retardation film 2 and the polarizing plate 3 is not illustrated. The adhesive layer 12 can be an adhesive layer for bonding to an organic EL display element, a touch sensor, etc., as in FIGS. 1(a) and 1(b). In this 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 layers of retardation films. When a plurality of retardation films are included 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 crack generation due to temperature changes, the optical laminate It is preferable that the puncture elastic modulus of all retardation films contained in the body be 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 in which the polymerizable liquid crystal compound is cured), the puncture elastic modulus of the present invention can be set to 50 g/mm or less. This is preferred because it is easy. Moreover, the retardation film may have an alignment layer for aligning the polymerizable liquid crystal compound. Further, at the manufacturing stage, it may further include a base material that supports the alignment layer.

A polymerizable liquid crystal compound is a compound that has a polymerizable group and can be in a liquid crystal state. The polymerizable liquid crystal compound is cured by the polymerizable groups of the polymerizable liquid crystal compound reacting with each other and polymerizing the polymerizable liquid crystal compound.
A layer in which the polymerizable liquid crystal compound is cured is formed, for example, on an alignment layer provided on a base material. The base material may be a long base material that has a function of supporting the alignment layer. This base material functions as a releasable support and can support a retardation layer and an alignment layer for transfer. Furthermore, it is preferable that the surface has adhesive strength to the extent that it can be peeled off. The base material may be a translucent (preferably optically transparent) thermoplastic resin, such as a chain polyolefin resin (such as a polypropylene resin) or a cyclic polyolefin resin (such as a norbornene resin). polyolefin resins; cellulose resins such as triacetylcellulose and diacetylcellulose; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate resins; (meth)acrylic resins such as methyl methacrylate resins; Polystyrene resin; Polyvinyl chloride resin; Acrylonitrile/butadiene/styrene resin; Acrylonitrile/styrene resin; Polyvinyl acetate resin; Polyvinylidene chloride resin; Polyamide resin; Polyacetal resin; Modified polyphenylene ether resin; The film may be made of a polysulfone resin; a polyethersulfone resin; a polyarylate resin; a polyamideimide resin; a polyimide resin; a maleimide resin.

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

Note that the base material may be subjected to various anti-blocking treatments. Examples of the blocking prevention treatment include an adhesion-promoting treatment, a treatment in which a filler or the like is kneaded, an embossing process (knurling process), and the like. By applying such anti-blocking treatment to the base material, it is possible to effectively prevent the base materials from sticking to each other when they are wound up, so-called blocking, and to manufacture optical films with high productivity. becomes possible.

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

Note that the alignment layer is not limited to a vertical alignment layer, but may be an alignment layer that horizontally aligns the molecular axis of the polymerizable liquid crystal compound, or may be an alignment layer that obliquely aligns the molecular axis of the polymerizable liquid crystal compound. . As the alignment layer, one that has a solvent resistance that does not dissolve when a composition containing a polymerizable liquid crystal compound described below is coated, etc., and has 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 alignment polymer, a photo alignment film, and a groove alignment layer in which a concavo-convex pattern or a plurality of grooves are formed on the surface for alignment. The thickness of the alignment layer typically ranges from 10 nm to 10,000 nm.

Further, the alignment layer has a function of supporting the retardation layer and may function as a releasable support. It may be capable of supporting a retardation layer for transfer, and may also have adhesive strength to the extent that its surface 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 crystal polymerizable non-liquid crystal compound that does not enter a liquid crystal state. The polymerizable groups of the polymerizable compound react with each other and the polymerizable compound is polymerized to become a resin. Such a resin is used as an alignment layer for aligning a polymerizable liquid crystal compound at the stage of forming a retardation layer, and as long as it is not included in a retardation film, it can be used as a material for a known alignment layer. The resin is not particularly limited as long as it is a resin, and a cured product obtained by curing a conventionally known monofunctional or polyfunctional (meth)acrylate monomer in the presence of a polymerization initiator can be used. Specifically, (meth)acrylate monomers include, for example, 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono-2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, and trimethylolpropane triacrylate. , lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate , cyclohexyl methacrylate, methacrylic acid, urethane acrylate and the like. Note that the resin may be one type of these or a mixture of two or more types.
After forming the retardation layer, the alignment layer can be peeled off and removed together with the base material before and after the step of laminating it with another optical film or the like.

Further, the retardation film can include an alignment layer for the purpose of improving the releasability from the base material and imparting film strength to the retardation film. When the retardation film includes an alignment layer, from the viewpoint of a puncture modulus of 50 g/mm or less, monofunctional or bifunctional (meth)acrylate monomers, imide monomers, or vinyl ether monomers are used as the resin for the alignment layer. It is preferable to use a cured product.
Monofunctional (meth)acrylate monomers include alkyl (meth)acrylates having 4 to 16 carbon atoms, β-carboxyalkyl (meth)acrylates having 2 to 14 carbon atoms, and alkylated phenyl (meth)acrylates having 2 to 14 carbon atoms. Acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, isobonyl (meth)acrylate, etc. are mentioned, and the bifunctional (meth)acrylate monomer includes 1,3-butanediol di(meth)acrylate. 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; Ethylene glycol di(meth)acrylate; Tetraethylene glycol di(meth)acrylate; Polyethylene glycol diacrylate; Bis(acryloyloxyethyl) ether of bisphenol A; Ethoxylated bisphenol A di(meth)acrylate; Propoxylated neopentyl glycol diacrylate (Meth)acrylate; Examples include ethoxylated neopentyl glycol di(meth)acrylate and 3-methylpentanediol di(meth)acrylate.
Furthermore, examples of imide resins obtained by curing imide monomers include polyamides, polyimides, and the like. Note that the imide resin may be one type of these or a mixture of two or more types.
Furthermore, the resin forming the alignment layer may contain monomers other than monofunctional or difunctional (meth)acrylate monomers, imide monomers, and vinyl ether monomers, but monofunctional or difunctional (meth)acrylate monomers may be included. The content of the acrylate monomer, imide monomer, and vinyl ether 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 monomers. .

When the orientation layer is included in the retardation film, the thickness of the orientation layer is usually in the range of 10 nm to 10,000 nm, and when the orientation of the retardation layer is in-plane orientation with respect to the film surface, the thickness of the orientation layer is , 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 alignment layer is within the above range, it is possible to improve the peelability of the base material and provide appropriate film strength.

Although the type of polymerizable liquid crystal compound used in this embodiment is not particularly limited, it is classified into a rod-shaped type (rod-shaped liquid crystal compound) and a disc-shaped type (disc-shaped liquid crystal compound, discotic liquid crystal compound) based on its shape. can. Furthermore, there are low-molecular type and high-molecular type, respectively. Note that polymers generally refer to those having a degree of polymerization of 100 or more (Polymer Physics/Phase Transition Dynamics, Masao Doi, p. 2, Iwanami Shoten, 1992).

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

As the rod-shaped liquid crystal compound, for example, those described in claim 1 of Japanese Patent Publication No. Hei 11-513019 can be suitably used. As the discotic liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A No. 2007-108732 or paragraphs [0013] to [0108] of JP-A No. 2010-244038 are preferable. It can be used for.

Two or more types 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 layer in which the polymerizable liquid crystal compound is cured 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 that can undergo 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 these, a (meth)acryloyl group is preferred. Note that the (meth)acryloyl group is a concept that includes both a methacryloyl group and an acryloyl group.

The layer in which the polymerizable liquid crystal compound is cured can be formed by applying, for example, a composition containing the polymerizable liquid crystal compound onto the alignment layer and irradiating it with active energy rays, as described below. The composition may contain components other than the above-mentioned polymerizable liquid crystal compound. For example, it is preferable that the composition contains a polymerization initiator. The polymerization initiator used is selected from, for example, a thermal polymerization initiator or a photopolymerization initiator depending on the type of polymerization reaction. Examples of the photopolymerization initiator include α-carbonyl compounds, acyloin ethers, α-hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, and combinations of triarylimidazole dimer and p-aminophenyl ketone. 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.
In the present invention, "hardened" refers to a state in which the formed layer alone can exist independently without deforming or flowing, 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 uniformity of the coating film and strength of the film. Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Among these, polyfunctional radically polymerizable monomers are preferred.

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 weight, more preferably 2 to 30% by weight, based on the total weight of the polymerizable liquid crystal compound.

Further, the composition may contain a surfactant from the viewpoint of uniformity of the coating film and strength of the film. Examples of the surfactant include conventionally known compounds. Among these, fluorine compounds are particularly preferred.

Further, the composition may contain a solvent, and organic solvents are preferably used. Examples of organic solvents include amides (e.g., N,N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), alkyl halides (e.g. , chloroform, dichloromethane), esters (eg, methyl acetate, ethyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), and ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Among them, alkyl halides and ketones are preferred. Furthermore, two or more types of organic solvents may be used in combination.

The composition also 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 promoter such as a polarizer interface side horizontal alignment agent and an air interface side horizontal alignment agent. It may contain various alignment agents such as an agent. Furthermore, the composition may contain an adhesion improver, a plasticizer, a polymer, etc. in addition to the above components.

The active energy rays include ultraviolet rays, visible light, electron beams, and X-rays, and 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 ultra-high-pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, and a wavelength range. Examples include an LED light source that emits light in the range of 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 rays is usually 100 mW/cm ² to 3,000 mW/cm ² in the case of ultraviolet B waves (wavelength range 280 to 310 nm). The ultraviolet irradiation intensity is preferably an intensity in a wavelength range effective for activating a cationic polymerization initiator or a radical polymerization initiator. The time for irradiating 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.

The ultraviolet rays can be irradiated once or in multiple times. Although it depends on the polymerization initiator used, the cumulative light amount at a wavelength of 365 nm is preferably 700 mJ/cm ² or more, more preferably 1,100 mJ/cm ² or more, and 1,300 mJ/cm ² or more. It is more preferable to do so. Setting the cumulative light amount as above is advantageous for increasing the polymerization rate of the polymerizable liquid crystal compound constituting the retardation film and improving the heat resistance. The integrated light amount at a wavelength of 365 nm is preferably 2,000 mJ/cm ² or less, more preferably 1,800 mJ/cm ² or less. Setting the above cumulative light amount 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, or 10°C or lower. The cooling time can be, for example, 10 seconds or more, or 20 seconds or more.

In this embodiment, the thickness of the retardation layer is preferably 0.5 μm or more. Further, the thickness of the retardation layer is preferably 10 μm or less, more preferably 5 μm or less. In addition, the upper limit value and lower limit value mentioned above can be combined arbitrarily. When the thickness of the retardation layer is equal to or greater than the lower limit, sufficient durability can be obtained. When the thickness of the retardation layer is less than or equal to the upper limit value, it can contribute to making the optical laminate thinner. The thickness of the retardation layer is such that the desired in-plane retardation value and thickness direction retardation value of the layer giving a retardation of λ/4, the layer giving a retardation of λ/2, or the positive C layer can be obtained. It can be adjusted accordingly.
The retardation film may include a stack of a plurality of retardation layers each having different retardation characteristics. Each retardation layer may be laminated via an adhesive or pressure-sensitive adhesive, or a composition containing a polymerizable liquid crystal compound may be applied to the surface of an already formed retardation layer and cured. .

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

On the other hand, when a retardation film is formed from a retardation layer and an alignment layer in which a polymerizable liquid crystal compound is cured, the retardation film is The lower limit of the puncture elastic 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, and even more preferably 30 g/mm. 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 mentioned above, the retardation film of the present invention may be composed of only a retardation layer or a retardation layer and an alignment layer. Formula (A)

It is preferable that the amount N of polymerizable groups represented by is 0.67 or less, more preferably 0.64 or less.
The amount of polymerizable groups 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 constituting the resin constituting the alignment layer constituting the retardation film. In addition, when a retardation film is comprised only of a retardation layer, AL=0.
Cwi indicates the content (mass%) of structural units derived from polymerizable compound i, based on all structural units derived from polymerizable compounds 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 that the polymerizable compound i that constitutes the alignment layer has.
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 hardened layer of a polymerizable liquid crystal compound.
Cwj indicates the content (mass%) of the structural units derived from the polymerizable liquid crystal compound j, based on 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 that the polymerizable liquid crystal compound i that constitutes the retardation layer has.
L _AL indicates the thickness (μm) of the alignment layer, and L _LC indicates the thickness (μm) of the retardation layer.
L _total indicates the sum of L _AL and L _LC .

When a temperature change occurs in a usage environment of a display device on which an optical laminate is laminated, expansion and contraction occur in the retardation film, other optical films, adhesives, and pressure-sensitive adhesive layers constituting the optical laminate. The effects of dimensional changes due to expansion and contraction of other constituent members tend to concentrate on the retardation film. The retardation film becomes unable to follow the dimensional changes of other members due to temperature changes, and cracks are likely to occur starting from the retardation film.
Cracks due to such temperature changes 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 made of a cured polymerizable liquid crystal compound. In particular, cracks are likely to occur when a retardation film is formed from a retardation layer or a retardation layer and an orientation layer, and a pressure-sensitive adhesive or adhesive layer is directly laminated on the retardation layer or orientation layer. However, when the layer has vertical alignment like a positive C layer, this tendency may become noticeable.
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 changes of other components due to the aforementioned temperature change. Even in the structure of a retardation film or an optical laminate that is prone to cracks as described above, the occurrence of cracks can be suitably suppressed.

The optical laminate of the present application may have two or more retardation films. When the optical laminate includes two layers of retardation films, the two layers are a layer that provides a retardation of λ/4 and a positive C layer, or a layer that provides a retardation of λ/4 and a layer that provides a retardation of λ/2. Preferably, it is a layer.
When the optical laminate includes two retardation films, the retardation layers of the respective retardation films may be laminated via an adhesive layer or a pressure-sensitive adhesive layer. From the viewpoint of thinning the optical laminate, the thickness of the retardation film formed by laminating a plurality of layers is preferably 3 to 30 μm, more preferably 5 to 25 μm.

In the configuration of an optical laminate, if there are two or more retardation films, and at least one of the retardation films has a retardation layer showing vertical alignment in which a polymerizable liquid crystal compound is cured, cracks may occur due to thermal shock. tends to occur more easily. In particular, when retardation films are laminated together via an active energy ray-curable adhesive and the storage modulus of the adhesive layer is 3000 MPa or more, cracks may occur significantly. 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 alignment. 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 an alignment layer is included in the retardation film, evaluation of wear resistance such as pencil hardness or steel wool hardness of the alignment layer can be used as an index for suppressing cracks due to thermal shock.
For example, pencil hardness is determined according to JIS K 5600-5-4:1999, and is expressed as the hardness of the hardest pencil that does not cause scratches when scratched with a pencil of each hardness. It is preferable that the pencil hardness of the alignment layer is 3B or less because this can suppress the occurrence of cracks due to thermal shock.
Steel wool hardness as another index can be determined by, for example, using a steel wool tester (manufactured by Daiei Seiki Co., Ltd.) and contacting the surface of the test object with a clean room wiper (BEMCOT AZ-8, manufactured by Asahi Kasei Corporation) with a load of 500 g. A 4-reciprocating abrasion test was conducted at a speed of 40 r/min, and the number of scratches was visually confirmed. The number of scratches measured by a steel wool test on the alignment layer is preferably 4 or more, more preferably 8 or more in order to suppress the occurrence of cracks due to thermal shock.
From the viewpoint of ease of handling 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 by the steel wool test is usually 50 or less, and 20 or less. It is preferable that there be one, 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 ^-1 , and even more preferably 20 to 60×10 ⁻¹³ Pa ⁻¹ . The photoelastic coefficient can be determined by applying stress (0.5N to 3N) by holding both ends of a sample (size 1cm x 10cm) using, for example, a phase difference measuring device KOBRA-WPR (manufactured by Oji Scientific Instruments Co., Ltd.). The retardation value (23° C./wavelength 550 nm) at the center of the sample is measured while applying the stress, and can be calculated from the slope of the function of stress and retardation value.

The optical laminate can have layers other than those shown in FIG. Examples of layers that the optical laminate may further include include optical functional layers such as a front plate, a light shielding pattern, and a polarizing plate, an adhesive layer or adhesive layer for laminating with other optical functional layers, a touch sensor, etc. can be mentioned. The front plate can be placed on the opposite side of the polarizing plate 3 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 light-shielding pattern is formed on the frame (non-display area) of the image display device, and can prevent the wiring of the image display device from being visually recognized by the user. The touch sensor can be laminated to 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 widest area corresponding to the display surface. "Substantially rectangular" means a shape in which at least one of the four corners (corners) is cut off so that it becomes an obtuse angle, or a shape in which the end face is perpendicular to the main surface. A part of the main surface has a recessed part (notch) in the in-plane direction, or a part of the main surface has a hole cut out in a shape such as a circle, an ellipse, a polygon, or a combination thereof. It means something that you may have.

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 short side length is 5 cm or more and 30 cm or less. The length 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 the film, it is preferably 150 μm or less, more preferably 105 μm or less, but if the thickness of the optical laminate is 105 μm or less, thermal shock may occur. In this case, cracks originating from the retardation film tend to spread throughout the optical laminate.
Even in the case of such a thin-film optical laminate, by setting the puncture elastic modulus of the retardation film within the range specified in the present application, it is possible to suitably suppress the occurrence of cracks due to temperature changes.

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

<Polarizing plate>
In the present invention, the polarizing plate refers to a laminate consisting of a polarizer 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 a pressure-sensitive adhesive layer. The members included in the polarizing plate will be explained below.

(1) Polarizer The polarizer included in a polarizing plate absorbs linearly polarized light whose vibration plane is parallel to its absorption axis, and transmits linearly polarized light whose vibration plane is perpendicular to its absorption axis (parallel to its transmission axis). It can be an absorptive polarizer with properties. As the polarizer included in the first layer, a polarizer in which a dichroic dye is adsorbed and aligned on a uniaxially stretched polyvinyl alcohol resin film can be suitably used. The polarizer is produced by, for example, a process in which a polyvinyl alcohol resin film is uniaxially stretched; a process in which a dichroic dye is adsorbed by dyeing a polyvinyl alcohol resin film with a dichroic dye; a process in which a dichroic dye is adsorbed; It can be produced by a method including a step of treating an alcohol-based resin film with a crosslinking liquid such as a boric acid aqueous solution; and a step of washing with water after the treatment with the crosslinking liquid.

As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other monomers that can be copolymerized. 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.

In this specification, "(meth)acrylic" means at least one selected from acrylic and methacryl. The same applies to "(meth)acryloyl", "(meth)acrylate", etc.

The degree of saponification of polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The average degree of polymerization of the polyvinyl alcohol resin is usually 1,000 to 10,000, preferably 1,500 to 5,000. The average degree of polymerization of polyvinyl alcohol resin can be determined in accordance with JIS K 6726.

A film made of such a polyvinyl alcohol resin is used as an original film of a polarizer (polarizer). The method of forming a polyvinyl alcohol resin into a film is not particularly limited, and any known method may be employed. The thickness of the polyvinyl alcohol base film is not particularly limited, but in order to make the thickness of the polarizer 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 resin film can be performed before, simultaneously with, or after dyeing with the dichroic dye. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during crosslinking treatment. Further, uniaxial stretching may be performed in these plural steps.

In the uniaxial stretching, it may be uniaxially stretched between rolls having different circumferential speeds, or it may be uniaxially stretched using hot rolls. Further, the uniaxial stretching may be dry stretching in which the film is stretched in the atmosphere, or wet stretching in which the polyvinyl alcohol resin film is stretched in a swollen state using a solvent or water. The stretching ratio is usually 3 to 8 times.

As a method for dyeing a polyvinyl alcohol resin film with a dichroic dye, for example, a method of immersing the film in an aqueous solution containing a dichroic dye is adopted. Iodine and dichroic organic dyes are used as the dichroic dye. In addition, it is preferable that the polyvinyl alcohol resin film is subjected to a immersion treatment in water before the dyeing treatment.

As the crosslinking treatment after dyeing with a dichroic dye, a method of immersing the dyed polyvinyl alcohol resin film in an aqueous solution containing boric acid is usually employed. When using iodine as the dichroic dye, 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, even more preferably 10 μm or less, 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 No. 2016-170368, a polarizer in which a dichroic dye is oriented in a cured film in which a liquid crystal compound is polymerized may be used. As the dichroic dye, one having absorption within the wavelength range of 380 to 800 nm can be used, and it is preferable to use an organic dye. Examples of dichroic dyes include azo compounds. 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 liquid crystallinity.

The shrinkage force of the polarizer is preferably 2.0 N/2 mm or less, more preferably 1.8 N/mm or less, and still more preferably 1.5 N/mm 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 that the film has negative birefringence. Here, negative birefringence means that a slow axis appears in a direction perpendicular to the stretching direction of the resin. Since the retardation film includes a retardation layer with positive birefringence, a retardation opposite to that of the retardation film due to thermal contraction of the polarizer is developed. It is thought that the color change will be smaller. Here, positive birefringence means that a slow axis is expressed in a direction parallel to the stretching direction of the retardation film.

The protective film laminated on the polarizer is made of a translucent (preferably optically transparent) thermoplastic resin, such as a chain polyolefin resin (polypropylene resin, etc.), a cyclic polyolefin resin (norbornene resin, etc.). Polyolefin resins such as triacetyl cellulose and diacetyl cellulose; Polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate resins; (meth) resins such as methyl methacrylate resins; 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 The film may be made of an ether resin; a polysulfone resin; a polyether sulfone resin; a polyarylate resin; a polyamideimide resin; a polyimide resin; a maleimide resin.

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, a polarizing plate with excellent durability can be obtained even when processed into an irregular shape.

A (meth)acrylic resin is a resin whose main constituent monomer is a compound having a (meth)acryloyl group. Specific examples of (meth)acrylic resins include poly(meth)acrylic esters such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymers; methyl methacrylate-(meth)acrylic acid Ester copolymer; Methyl methacrylate-acrylic ester-(meth)acrylic acid copolymer; Methyl (meth)acrylate-styrene copolymer (MS resin, etc.); Methyl methacrylate and alicyclic hydrocarbon group (eg, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). Preferably, a polymer containing _methyl methacrylate as a main component (50 to 100 % by weight, preferably 70 to 100% by weight).

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

The (meth)acrylic resin may preferably have a structural unit that exhibits positive birefringence within a range that has negative birefringence. If it has a structural unit that expresses positive birefringence and a structural unit that expresses negative birefringence, it is possible to control the phase difference of the (meth)acrylic resin film by adjusting the abundance ratio. It is possible to obtain a (meth)acrylic resin film with a low retardation. Structural units that exhibit positive birefringence include, for example, structural units constituting lactone rings, polycarbonates, polyvinyl alcohol, cellulose acetate, polyesters, polyarylates, polyimides, polyolefins, etc., and those represented by the general formula (1) described below. Examples include structural units. Examples of structural units that exhibit negative birefringence include structural units derived from styrene monomers, maleimide monomers, etc., structural units of polymethyl methacrylate, and structural units represented by general formula (3) described below. Can be mentioned.

As the (meth)acrylic resin, a (meth)acrylic resin having a lactone ring structure or a glutarimide structure is preferably used. (Meth)acrylic resins having a lactone ring structure or a glutarimide structure have 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, it is possible to obtain a (meth)acrylic resin film with low moisture permeability, small retardation, and small ultraviolet transmittance, as described above. (Meth)acrylic resins having a glutarimide structure (hereinafter also referred to as glutarimide resins) are disclosed in, for example, JP-A No. 2006-309033, JP-A No. 2006-317560, JP-A No. 2006-328329, and JP-A No. 2006-328329. 2006-328334, 2006-337491, 2006-337492, 2006-337493, 2006-337569, 2007-009182, 2009- It is described in No. 161744. These descriptions 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 referred to as (meth)). (also referred to as 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 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, or an alkyl group having 3 to 8 carbon atoms. 12 cycloalkyl group, or a substituent containing an aromatic ring having 5 to 15 carbon atoms. In 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, or an alkyl group having 3 to 18 carbon atoms. 12 cycloalkyl group, or a substituent containing 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 each independently hydrogen or a methyl group, and R ³ is hydrogen, a methyl group, a butyl group, or a cyclohexyl group, and more preferably , R ¹ is a methyl group, R ² is hydrogen, and R ³ is a methyl group.

The glutarimide resin may contain only a single type of glutarimide unit, or may contain multiple types in which R ¹ , R ² , and R ³ in the general formula (1) are different. good.

The glutarimide unit can be formed by imidizing the (meth)acrylic acid ester unit represented by the above general formula (2). In addition, 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; acrylic 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 each independently hydrogen or a methyl group, R ⁶ is hydrogen or a methyl group, and more preferably R ⁴ is hydrogen. , R ⁵ is a methyl group, and R ⁶ is a methyl group.

The above glutarimide resin may contain only a single type of (meth)acrylic acid ester unit, or may contain multiple types in which R ⁴ , R ⁵ and R ⁶ in the above general formula (2) are different. May contain.

The glutarimide resin preferably contains styrene, α-methylstyrene, etc., 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 with a lower retardation can be obtained.

The above-mentioned glutarimide resin may contain only a single type of aromatic vinyl unit, or may contain a plurality of types in which 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 ^R3 . The content of glutarimide units is preferably 1% to 80% by weight, more preferably 1% to 70% by weight, even more preferably 1% by weight, based on the total structural units of the glutarimide resin. 60% by weight, particularly preferably 1% to 50% by weight. If the content of glutarimide units is within this range, a (meth)acrylic resin film with excellent heat resistance and low retardation can be obtained.

The content of the aromatic vinyl unit in the glutarimide resin can be appropriately set depending on the purpose and desired properties. Depending on the application, the content of aromatic vinyl units may be zero. When an aromatic vinyl unit is included, its content is preferably 10% to 80% by weight, more preferably 20% to 80% by weight, based on the glutarimide unit of the glutarimide resin. More preferably, it is 20% to 60% by weight, particularly preferably 20% to 50% by weight. If the content of aromatic vinyl units is within this range, a (meth)acrylic resin film with low retardation and excellent heat resistance and mechanical strength can be obtained.

The above-mentioned glutarimide resin may further be copolymerized with other structural units other than glutarimide units, (meth)acrylic acid ester units, and aromatic vinyl units, if necessary. Other structural units include, for example, structures composed of nitrile monomers such as acrylonitrile and methacrylonitrile, maleimide monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide. Units are listed. These other structural units may be directly copolymerized or graft copolymerized in the glutarimide resin.

The (meth)acrylic resin film may contain any suitable additives depending on the purpose. Examples of additives include antioxidants such as hindered phenol, phosphorus, and sulfur; stabilizers such as light stabilizers, ultraviolet absorbers, weather stabilizers, and heat stabilizers; glass fibers, carbon fibers, etc. Reinforcing materials; near-infrared absorbers; flame retardants such as tris(dibromopropyl) phosphate, triallyl phosphate, and antimony oxide; antistatic agents such as anionic, cationic, and nonionic surfactants; inorganic pigments, organic pigments, Coloring agents such as dyes; organic fillers and inorganic fillers; resin modifiers; plasticizers; lubricants; retardation reducing agents and the like. The types, combinations, contents, etc. of the additives contained can be appropriately set depending on the purpose and desired characteristics.

The method for producing the above (meth)acrylic resin film is not particularly limited, but includes, for example, a (meth)acrylic resin, an ultraviolet absorber, and other polymers and additives as necessary. These can be thoroughly mixed using any appropriate mixing method to form a thermoplastic resin composition in advance, which can then be formed into a film. Alternatively, the (meth)acrylic resin, the ultraviolet absorber, and other polymers and additives as necessary are made into separate solutions and then mixed to form a uniform mixture, and then formed into a film. You may.

To produce the thermoplastic resin composition, the film raw materials are preblended using any appropriate mixer such as an omnimixer, 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 may be used, such as an extruder such as a single-screw extruder or twin-screw extruder, or a pressure kneader. Can be done.

Examples of the film forming method include any suitable film forming method, such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, a compression molding method, and the like. Melt extrusion methods are preferred. Since the melt extrusion method does not use a solvent, it is possible to reduce manufacturing costs and the impact of solvents on the global environment and work environment.

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

When forming a film using the above T-die method, attach a T-die to the tip of a known single-screw extruder or twin-screw extruder, and wind up the extruded film to obtain a roll-shaped film. Can be done. At this time, it is also possible to perform uniaxial stretching by appropriately adjusting the temperature of the winding roll and applying stretching in the extrusion direction. Moreover, simultaneous biaxial stretching, sequential biaxial stretching, etc. can also be performed by stretching the film in a direction perpendicular to the extrusion direction.

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

The above-mentioned stretching temperature is preferably close to the glass transition temperature of the thermoplastic resin composition that is the raw material for the film, and specifically, preferably (glass transition temperature -30°C) to (glass transition temperature +30°C), more It is preferably within the range of (glass transition temperature -20°C) to (glass transition temperature +20°C). If the stretching temperature is lower than (glass transition temperature - 30° C.), there is a risk that the obtained film will have a large haze, or the film will tear or crack, making it impossible to obtain a predetermined stretching ratio. On the other hand, if the stretching temperature exceeds (glass transition temperature + 30°C), the resulting film may have large thickness unevenness, and mechanical properties such as elongation, tear propagation strength, and rolling fatigue resistance may not be sufficiently improved. There is a tendency to Furthermore, troubles such as the film sticking to the roll tend to occur more easily.

The above stretching ratio is preferably 1.1 to 3 times, more preferably 1.3 to 2.5 times. When the stretching ratio is within this range, the mechanical properties such as elongation rate, tear propagation strength, and rolling fatigue resistance of the film can be significantly improved. As a result, it is possible to produce a film with small thickness unevenness, substantially zero birefringence (therefore, small retardation), and low haze.

The above (meth)acrylic resin film can be subjected to heat treatment (annealing) etc. after the stretching treatment in order to stabilize its optical isotropy and mechanical properties. Any suitable conditions may be adopted as the conditions for the heat treatment.

The photoelastic coefficient of the (meth)acrylic resin film is preferably -3 to -100x10 ^-13 Pa ^-1 , more preferably -5 to -70x10 ^-13 Pa ^-1 , even more preferably -15 to -50×10 ^-13 Pa ^-1 . Note that 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, 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, there is a risk that transparency may decrease.

When laminating protective films on both sides of the polarizer, the same films as above may be laminated on both sides, or other resin films may be used. For example, olefin resin films, polyester resin films, and cellulose resin films are preferably used.

Chain polyolefin resins include polyethylene resins (polyethylene resins that are homopolymers of ethylene and copolymers mainly composed of ethylene), polypropylene resins (polypropylene resins that are homopolymers of propylene, and copolymers mainly composed of propylene). In addition to homopolymers of chain olefins such as (copolymers), copolymers consisting of two or more types of chain olefins can be mentioned.

Cyclic polyolefin resin is a general term for resins that are polymerized using cyclic olefins as polymerization units, and is described, for example, in JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, etc. Examples include resins that are Specific examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, and copolymers of cyclic olefins with chain olefins 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 hydrogenated product thereof. Among these, a norbornene resin using a norbornene monomer such as norbornene or a polycyclic norbornene monomer as the cyclic olefin is preferably used.

The polyester resin is a resin having an ester bond, excluding the cellulose ester resin described below, and is generally a polycondensate of a polyhydric carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polyvalent carboxylic acid or its derivative, a divalent dicarboxylic acid or its derivative can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalene dicarboxylate. As the polyhydric alcohol, divalent diols can be used, such as ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A typical example of polyester resin is polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

Cellulose ester resin is an ester of cellulose and fatty acid. Specific examples of cellulose ester resins include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Also included are copolymers of these and those in which some of the hydroxyl groups are modified with other substituents. Among these, cellulose triacetate (triacetylcellulose) is particularly preferred.

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

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

The protective film can be bonded to the polarizer via, for example, an adhesive layer or a pressure-sensitive 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 preferably a water-based adhesive or an active energy ray-curable adhesive. As the adhesive layer, those described below can be used.

Examples of the water-based adhesive include adhesives made of polyvinyl alcohol resin aqueous solutions, water-based two-component urethane emulsion adhesives, and the like. Among them, a water-based adhesive made of an aqueous solution of a polyvinyl alcohol resin is preferably used. Polyvinyl alcohol-based resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as vinyl alcohol homopolymers obtained by saponifying vinyl acetate and other monomers that can be copolymerized with vinyl acetate. A polyvinyl alcohol copolymer obtained by saponifying a polymer, a modified polyvinyl alcohol copolymer obtained by partially modifying the hydroxyl groups thereof, or the like can be used. The water-based adhesive can contain a crosslinking agent such as an aldehyde compound (such as glyoxal), an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.

When using a water-based adhesive, it is preferable to perform a drying step to remove water contained in the water-based adhesive after bonding the polarizer and the protective film. After the drying step, a curing step of curing at a temperature of, for example, 20 to 45° C. may be provided.

The above-mentioned 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 preferably an ultraviolet curable adhesive. It is.

The curable compound may be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of cationic polymerizable curable compounds include epoxy compounds (compounds having one or more epoxy groups in the molecule) and oxetane compounds (compounds having one or more oxetane rings in the molecule). ) or a combination thereof. Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule) and radically polymerizable double bonds. Other vinyl compounds or combinations thereof can be mentioned. A cationically polymerizable curable compound and a radically polymerizable curable compound may be used together. 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 bonding the polarizer and the protective film, at least one of the bonding surfaces thereof may be subjected to surface activation treatment in order to improve adhesiveness. Surface activation treatments include dry treatments such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionizing active ray treatment (ultraviolet treatment, electron beam treatment, etc.) Examples include wet treatments such as ultrasonic treatment using a solvent such as water or acetone, saponification treatment, and anchor coating treatment. These surface activation treatments may be performed alone or in combination of two or more.

When protective films are pasted on both sides of the polarizer, the adhesives for pasting these protective films may be the same type of adhesive or different types of adhesives.
In addition, the above-mentioned adhesive or bonding method using an adhesive can be used not only for bonding a polarizer and a protective film, but also for bonding other optical functional layers included 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 to bond the retardation films together.

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

Examples of the (meth)acrylic resin (base polymer) used in the adhesive composition include butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-(meth)acrylate. Polymers or copolymers containing one or more types of (meth)acrylic esters such as ethylhexyl as monomers are preferably used. It is preferable to copolymerize a polar monomer with the base polymer. 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 include monomers having carboxyl groups, hydroxyl groups, amide groups, amino groups, epoxy groups, etc., such as meth)acrylates.

The pressure-sensitive adhesive composition may contain only the above base polymer, but usually further contains a crosslinking agent. Examples of crosslinking agents include metal ions with a valence of two or more that form carboxylic acid metal salts with carboxyl groups; polyamine compounds that form amide bonds with carboxyl groups; polyamine compounds that form amide bonds with carboxyl groups; Examples include epoxy compounds and polyols that form ester bonds with carboxyl groups; polyisocyanate compounds that form amide bonds with carboxyl groups. Among these, polyisocyanate compounds are preferred.

Although the adhesive layer and the adhesive composition have been described as an example of use in the adhesive layer 12 used for laminating the optical laminate of the present invention and an organic EL display element, the present invention is not limited thereto. For example, it may be used to bond the optical laminate of the present invention with other optical functional layers, or to bond optical functional layers constituting the optical laminate.

<Front plate>
The front plate is arranged on the viewing side of the polarizing plate. The front plate can be laminated to the polarizing plate via an adhesive layer. Examples of the adhesive layer include the above-mentioned pressure-sensitive 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 have a light shielding pattern 6 formed thereon.

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

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

Examples of resin films include cycloolefin derivatives having monomer units containing cycloolefins such as norbornene or polycyclic norbornene monomers, cellulose (diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl ester cellulose) , propionylcellulose, butyrylcellulose, acetylpropionylcellulose) 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, polyetherketone, polyetheretherketone, polyethersulfone, polymethylmethacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate It may also be a film made of a polymer such as polyurethane, epoxy, or the like. As the resin film, an unstretched, uniaxially or biaxially stretched film can be used. These polymers can be used alone or in a mixture of two or more. Examples of resin films include polyamide-imide films or polyimide films that have excellent transparency and heat resistance, uniaxially or biaxially stretched polyester films, and cycloolefin derivative films that have excellent transparency and heat resistance and can accommodate larger films. , polymethyl methacrylate films, and triacetyl cellulose and isobutyl ester cellulose films that are transparent and optically free of anisotropy 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 forms a crosslinked structure by irradiating light or thermal energy. The hard coat layer can be formed by curing a hard coat composition that simultaneously contains a photocurable (meth)acrylate monomer or oligomer and a photocurable epoxy monomer or oligomer. The photocurable (meth)acrylate monomer may include one or more selected from the group consisting 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 include one or more selected from the group consisting of a solvent, a photoinitiator, and an additive. The additive may include one or more selected from the group consisting of inorganic nanoparticles, leveling agents, and stabilizers, as well as other components commonly used in the art, such as antiseptics. It may further contain oxidizing agents, UV absorbers, surfactants, lubricants, antifouling agents, and the like.

<Shading pattern>
The light-blocking pattern may be provided as at least part of the front plate or a 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 light shielding pattern can hide each wiring of the display device so that it is not visible to the user. The color and/or material of the light shielding pattern is not particularly limited, and may be formed of resin materials having various colors such as black, white, and gold. In one embodiment, the thickness of the light shielding pattern may be in the range of 2 μm to 50 μm, preferably 4 μm to 30 μm, and more preferably 6 μm to 15 μm. Furthermore, in order to suppress the inclusion of air bubbles and visibility of the boundary due to the step difference between the light shielding pattern and the display section, a shape can be given to the light shielding pattern.

<Touch sensor>
A touch sensor is used as an input means. Various types of touch sensors have been proposed, including a resistive film type, a surface acoustic wave type, an infrared type, an electromagnetic induction type, and a capacitance type, and any of these types may be used. Among these, the capacitive method is preferable. A capacitive touch sensor is divided into an active area and a non-active area located outside the active area. The active area is an area corresponding to the area where the screen is displayed on the display panel (display part), and is 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 area. The touch sensor includes a substrate; a sensing pattern formed on an active area of the substrate; and sensing lines formed on a non-active area of the substrate and connected to an external driving circuit through the sensing pattern and a pad part. Can be done. As the substrate, glass or the same material as the resin film that constitutes 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 may include a first pattern formed in a first direction and a second pattern formed in a second direction. The first pattern and the second pattern are arranged in different directions. The first pattern and the second pattern are formed on the same layer and must be electrically connected to each other in order to sense a touched point. The first pattern has unit patterns connected to each other via joints, but the second pattern has a structure in which each unit pattern is isolated from each other in an island configuration, so the second pattern is electrically connected to the unit patterns. 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 zinc tin oxide (IZTO), cadmium tin oxide (CTO), PEDOT (poly(3,4- ethylenedioxythiophene), carbon nanotubes (CNT), graphene, metal wires, etc., and these can be used alone or in a mixture of two or more. Preferably ITO can be used. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, terenium, and chromium. These can be used alone or in combination of two or more.

The bridge electrode may be formed on the sensing pattern through an insulation layer, and the bridge electrode may be formed on the substrate, and the insulation layer and the sensing pattern may be formed on the bridge electrode. The bridge electrode can also be made of the same material as the sensing pattern, such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of these. You can also do that. 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 may be formed only between the joint of the first pattern and the bridge electrode, or may be formed as 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.
Touch sensors detect the difference in transmittance between patterned areas and non-patterned areas, specifically the difference in light transmittance induced by the difference in refractive index in these areas. An optical adjustment layer may further be included between the substrate and the electrodes as a means for appropriately compensating for the oxidation, and the optical adjustment layer may include an inorganic insulating material or an organic insulating material. The optical adjustment 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 include inorganic particles. Inorganic particles can increase the refractive index of the optical adjustment layer.

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

<Method for manufacturing optical laminate>
A method for manufacturing an optical laminate will be described using the optical laminate shown in FIGS. 1(a) to 1(c) as an example.
The optical laminate 100 (FIG. 1(a)) can be manufactured, for example, as follows. An alignment layer 11 is formed on a base material, and a coating liquid containing a polymerizable liquid crystal compound is applied onto the alignment layer 11. In a state in which the polymerizable liquid crystal compound is oriented, the polymerizable liquid crystal compound is cured by heat treatment or irradiation with active energy rays. After the polymerizable liquid crystal compound is cured and the retardation layer 10 is formed, the base material is peeled off, and the adhesive layer 12 formed on the release film is laminated on the surface of the alignment layer 11 from which the base material has been peeled off.
In the case of the optical laminate 101 shown in FIG. 1(b), the steps up to the formation of the retardation layer 10 are the same as the optical laminate 100 shown in FIG. 1(a), and after forming the retardation layer 10, The retardation layer 10 and the second retardation film are laminated with an adhesive layer 13 interposed therebetween. When the optical laminate 100 and the retardation layer 10 are elongated, the respective members may be bonded together via the adhesive layer 13 in a roll-to-roll manner. After laminating the optical laminate 100 and the second retardation film, the base material is peeled off, and the adhesive layer 12 formed on the release film is laminated on the surface of the alignment layer 11 from which the base material has been peeled off.
In the case of the optical laminate 102 shown in FIG. 1(c), the polarizing plate 3 is first manufactured. The polarizing plate 3 can be manufactured by laminating a polarizer and a protective film through adhesive layers, respectively. The protective film only needs to be laminated on at least one surface of the polarizer. A polarizing plate may be manufactured by preparing long members, pasting each member together in a roll-to-roll manner, and then cutting it into a predetermined shape, or by cutting each member into a predetermined shape. Afterwards, they may be pasted together. After bonding the protective film to the polarizer, a heating step or a humidity conditioning step may be provided. The retardation film is the same as the optical laminate 101 shown in FIG. A polarizing plate 3 is laminated on the surface via an adhesive layer or a pressure-sensitive adhesive layer. When the polarizing plate 3 and the optical laminate 101 are elongated, the respective members may be bonded together in a roll-to-roll manner. After laminating the polarizing plate 3, the base material is peeled off, and the adhesive layer 12 formed on the release film is laminated on the surface of the alignment layer 11 from which the base material has been peeled off.

Then, the release film laminated on the adhesive layer 12 is peeled off, and the optical laminate and the organic EL display element are bonded together via the adhesive layer 12, thereby producing an organic EL display device.

<Application>
The optical laminate of the present invention can be used in various display devices. A display device is a device having a display element, and includes a light emitting element or a light emitting device as a light emitting source. Examples of display devices include liquid crystal display devices, organic EL display devices, inorganic electroluminescence (hereinafter also referred to as inorganic EL) display devices, electron emission display devices (for example, field emission displays (also referred to as FEDs), and surface field emission displays). (also referred to as SED)), electronic paper (display devices using electronic ink or electrophoretic elements, plasma display devices, projection type display devices (e.g. grating light valve (also referred to as GLV) display devices, digital micromirror devices (DMD) ) and piezoelectric ceramic displays.Liquid crystal display devices include both transmissive liquid crystal display devices and semi-transmissive liquid crystal display devices.These display devices are capable of displaying two-dimensional images. It may be a display device that displays a three-dimensional image, or a stereoscopic display device that displays a three-dimensional image.The optical laminate can be particularly effectively used in an organic EL display device or an inorganic EL display device. .

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

Further, the display device can be a flexible display device, and 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 viewing side with respect to the organic EL display element, and is configured to be bendable. Bendable means capable of being bent without cracking or breaking. When applying the optical laminate of the present invention to a flexible organic EL display device, the optical laminate preferably includes at least one of a front plate and a touch sensor.

A specific optical laminate includes a front plate, a polarizing plate, a retardation film, and a touch sensor laminated in this order from the viewing side, or a front plate, a touch sensor, a polarizing plate, and a retardation film laminated in this order from the viewing side. For example, the following embodiments can be mentioned. It is preferable that a polarizing plate is present on the viewing side of the touch sensor because the pattern of the touch sensor becomes difficult to see and the visibility of the displayed image improves. Each member can be laminated using an adhesive, a pressure-sensitive adhesive, or the like. Furthermore, a light-shielding pattern formed on at least one surface of any one of the layers of the front plate, polarizing plate, retardation film, and touch sensor can be provided.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. In the examples, parts and percentages indicating the content or amount used are based on weight unless otherwise specified. In addition, the measurement of each physical property in the following examples was performed by the following method.

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

(Measurement of piercing elastic modulus)
The first retardation film with a base film obtained in Examples and Comparative Examples was cut into pieces measuring 40 mm in length and 40 mm in width. In addition, a glued mount having a length of 40 mm and a width of 40 mm was prepared. This glued mount has a 30 mm x 30 mm square cut out in the center. After laminating the above laminate to the adhesive mount so that the surface of the retardation layer 1 is in contact with the adhesive on the adhesive mount, the base material is peeled off from the first retardation film to obtain a sample for the puncture test. Created.

The puncture elastic modulus was measured as follows. The test was carried out by attaching a needle to a "NDG5 piercing tester" manufactured by Kato Tech Co., Ltd. A needle is pierced perpendicularly to the main surface of the test sample (the surface of the retardation layer 1), and the stress F (g) just before the puncture test sample breaks and the amount of strain S (mm ) was calculated, and the puncture elastic modulus (g/mm) was calculated as stress F (g)/strain amount S (mm). The needle used had a tip diameter of 1 mmφ and a diameter of 0.5R. The needle piercing speed was 0.33 cm/sec. Table 1 shows the puncture elastic modulus of the retardation film 1. The measurements were 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 abrasion resistance of the surface of the alignment layer of the retardation film was evaluated using a steel wool test.
Using a steel wool tester (manufactured by Daiei Seiki Co., Ltd.), each test was carried out on a cyclic polyolefin resin (COP) substrate (thickness 20 μm) on which a clean room wiper (BEMCOT AZ-8, manufactured by Asahi Kasei Corporation) was placed on a glass plate. The surface of the alignment layer formed in the same manner as in Examples and Comparative Examples was brought into contact with a load of 500 g, and a 4-reciprocating abrasion test was performed at a speed of 40 r/min, and the number of scratches that occurred was counted visually under fluorescent lighting. Ta.

(4) Abrasion resistance evaluation (pencil hardness evaluation)
The surface hardness of the surface of the alignment layer of the retardation film was evaluated using a pencil hardness test.
Using a pencil hardness tester (No. 553-M1 manufactured by Yasuda Seiki Seisakusho), a cyclic polyolefin resin (COP) base material (thickness 20 μm) was prepared by placing a test pencil (Unistar manufactured by Mitsubishi Pencil Co., Ltd.) on a glass plate. The hardness test was carried out at a speed of 0.5 mm/sec by contacting the surface of the alignment layer formed in the same manner as in each Example and Comparative Example from an angle of 45 degrees with a load of 500 g, and visually observing it under fluorescent light. The presence or absence of scratches that occurred was counted. Out of 5 tests, the hardness was confirmed to cause one or less scratches.

[Example 1]
(Production of first retardation film 1)
As a composition for forming an alignment layer,
10.0 parts by weight of polyethylene glycol di(meth)acrylate (A-600 manufactured by Shin-Nakamura Chemical Co., Ltd.),
10.0 parts by weight of trimethylolpropane triacrylate (A-TMPT manufactured by Shin-Nakamura Chemical Co., Ltd.),
10.0 parts by weight of 1,6-hexanediol di(meth)acrylate (A-HD-N manufactured by Shin-Nakamura Chemical Co., Ltd.),
1.50 parts by weight of Irgacure 907 (Irg-907 manufactured by BASF) as a photopolymerization initiator,
A coating solution for forming an alignment layer was prepared by dissolving it in 70.0 parts by weight of a solvent methyl ethyl ketone.

A long cyclic olefin resin film (manufactured by 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 using a bar coater. Coated.
After applying heat treatment to the coated layer at a temperature of 80°C for 60 seconds, it is irradiated with ultraviolet rays (UVB) at 220 mJ/ ^cm2 to polymerize and harden the composition for forming an alignment layer, and then apply it on the base film. An alignment layer 1 having a thickness of 3.5 μm was formed on the substrate.

As a composition for forming a retardation, 20.0 parts by weight of a photopolymerizable nematic liquid crystal compound (RMM28B, manufactured by Merck & Co., Ltd.) and 1.0 parts by weight of Irgacure 907 (manufactured by BASF, Irg-907) as a photopolymerization initiator. , was dissolved in 80.0 parts by weight of propylene glycol monomethyl ether acetate as a solvent to prepare a coating liquid for forming a retardation layer.
A coating solution 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. Thereafter, ultraviolet light (UVB) was irradiated at 220 mJ/cm ² to polymerize and harden the composition for forming a retardation layer, thereby forming a retardation layer 1 with a thickness of 0.7 μm on the alignment layer. In this manner, a first retardation film 1 consisting of an alignment layer 1 and a retardation layer 1 was obtained on a base film. This first retardation film 1 showed a retardation in the thickness direction. Furthermore, it was confirmed that the first retardation film 1 could be peeled off from the base film.

(Preparation of polarizing plate)
A polyvinyl alcohol film with a thickness of 20 μm (average degree of polymerization of about 2400, degree of saponification of 99.9 mol% or more) was uniaxially stretched to about 4 times by dry stretching, and then immersed in pure water at 40°C while maintaining the tension state. After being immersed for 40 seconds, it was immersed in an aqueous solution with a weight ratio of iodine/potassium iodide/water of 0.052/5.7/100 at 28° C. for 30 seconds for dyeing treatment. Thereafter, 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, the polyvinyl alcohol film was dried at 60°C for 50 seconds and then at 75°C for 20 seconds while being held under a tension of 300N, so that iodine was adsorbed and oriented in the polyvinyl alcohol film. An absorption type polarizer film having a thickness of 8 μm was obtained. A water-based adhesive consisting of an aqueous polyvinyl alcohol resin solution was applied to both sides of the polarizer film obtained, and a protective film (COP film manufactured by Zeon, Zeonor ZF14) was applied to one side of the polarizer film, and a protective film (Fuji Film) was applied to the other side. TAC film produced by Fujitac TJ25) was laminated to obtain a polarizing plate with double-sided protective film.

(Preparation of optical laminate)
After peeling off one of the release films of a sheet-like adhesive with a double-sided release film (thickness 25 μm, manufactured by Lintec Corporation P-3132) and bonding it to the TAC film side surface of the obtained polarizing plate via an adhesive layer agent, The release film on the other side of the sheet-like adhesive was peeled off, and the adhesive layer was laminated on the TAC film side surface of the polarizing plate. After the polarizing plate was bonded to the surface of the first retardation film on the retardation layer 1 side via the laminated adhesive layer, the base film was peeled off from the first retardation film 1. Furthermore, after peeling off one of the release films of the sheet-like adhesive with double-sided release film, it is bonded to the peeled side of the base film of the first retardation film 1 via the adhesive layer, so that the laminated structure is An optical laminate consisting of 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 compositions for forming the alignment layer 1 and the retardation layer 1 constituting the first retardation film were changed in the blending ratio and thickness shown in Table 1. , optical laminates of Comparative Examples 1 and 2 were produced. Moreover, 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 solution for forming an alignment layer was prepared using the composition for forming an alignment layer using the materials and compounding ratios shown in Table 1, and the coating layer of the coating solution 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. Moreover, the first retardation film obtained in Example 4 showed a retardation in the thickness direction.

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

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

Furthermore, 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.

Polymerizable liquid crystal compound A was produced by the method described in JP-A-2010-31223. Furthermore, polymerizable liquid crystal compound B was produced according to the method described in JP-A No. 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 in which a polymerizable liquid crystal compound is cured]
Corona treatment was performed on a 50 μm thick cycloolefin film (trade name “ZF-14-50” manufactured by Nippon Zeon Co., Ltd.) as a base material. A composition for forming an alignment film was applied to the corona-treated surface using a bar coater. The coated 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" manufactured by Ushio Inc.] to obtain an alignment film. Polarized UV irradiation was performed such that the cumulative amount of light at a wavelength of 313 nm was 100 mJ/cm ² .

Subsequently, a 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 cumulative amount of light at a wavelength of 365 nm was 250 mJ/cm ² . Immediately after irradiation, the cured film was placed in an oven set at 5° C. for 20 seconds as a cooling step. 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 consisting of an alignment film and a layer of a cured polymerizable liquid crystal compound on a base material. This first retardation film 2 showed a retardation in the in-plane direction. An optical laminate was obtained in the same manner as in Example 1, using the obtained first retardation film 2 instead of the first retardation film 1.

[Example 6]
A first retardation film was created in the same manner as in Comparative Example 1, and when producing an optical laminate, the alignment layer 1 and the retardation layer 1 were peeled off, and the first retardation film was removed from the retardation layer 1. An optical laminate of Example 6 was produced in the same manner as in Example 1 except that the optical laminate of Example 6 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 each was laminated to a glass plate via the exposed adhesive layer to form the state shown in FIG. 3. A thermal shock resistance test was conducted using the following method.
The pen tip of an Eriksen pen (manufactured by Eriksen, Model No. 318) set at 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 a starting point. Two other similar starting points (total of 3 locations) were established at equal intervals. Thereafter, several cycles of a thermal shock test (ESPEC CORP. product name: TSA-303EL-W) were conducted, each cycle consisting of -20°C for 30 minutes and 60°C for 30 minutes. Before the thermal shock test, an Erichsen pen was pressed against the surface of the polarizing plate in the optical laminate to measure the length of the crack that occurred from each starting point, and the average value of the crack measurement results from the three starting points was calculated as the crack length. (mm).

Puncture modulus, film thickness, abrasion resistance evaluation (steel wool, pencil hardness) of the first retardation films obtained in Examples 1 to 6 and Comparative Examples 1 and 2, and thermal shock test of the optical laminate 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 peeling the base film from the laminate of the first retardation film and the base film. The measurement was performed by pressing a piercing jig against the retardation film (retardation layer 1 + orientation layer 1) from the retardation layer 1 side. For the first retardation film of Example 6, the base film and the alignment layer 1 were peeled from the retardation layer 1, and the results were measured for the first retardation film (only the retardation layer 1). In addition, abrasion resistance evaluation was performed on the alignment 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 shows the thickness L _AL of the alignment layer in the retardation film obtained in each Example and each Comparative Example, the content Cwi of units derived from the polymerizable compound i in the resin constituting the alignment layer, and the polymerizability The molecular weight Mi and number of functional groups Ni of compound i are shown. The amount of polymerizable groups in the alignment layer is calculated using formula (A-1)

This is the 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。 Table 3 also shows the thickness _LLC of the retardation layer in the retardation films obtained in each Example and each Comparative Example, and the content Cwj of units derived from the polymerizable liquid crystal compound j constituting the retardation layer. , represents the molecular weight Mj and the number Nj of functional groups of the polymerizable liquid crystal compound j. The amount of polymerizable groups in the retardation layer is calculated using formula (A-2)

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

Advantageous Effects of Invention According to the present invention, it is possible to provide an optical laminate including a retardation film, which can suppress the occurrence of cracks even in an environment subject to rapid temperature changes, which is useful.

1 First retardation film (retardation film)
2 Second retardation film 3 Polarizing plate 4 Organic EL display element 5 Front plate 6 Light shielding pattern 10 Retardation 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 (7)

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 a break occurs,
The piercing elastic modulus is calculated using the following formula (1) using the stress F (g) applied to the retardation film from the tip of the piercing jig and the amount of strain S (mm) of the retardation film. 15 g/mm or more and 50 g/mm or less, where the strain amount S is the amount of displacement due to deflection of the film in the puncture direction, and the puncture elastic modulus is measured with the film at the center. Measurement was carried out using a measurement sample pasted on a glued mount with a square cutout of 30 mm x 30 mm, under conditions of pressing the tip of a stabbing jig with a tip diameter of 1 mm φ 0.5R at a speed of 0.33 cm / sec. and the retardation film includes a transfer type retardation layer having vertical alignment properties, in which a rod-shaped liquid crystal compound that is a polymerizable liquid crystal compound is cured, and the retardation film includes a cured product of a (meth)acrylate monomer. The retardation film further includes a transfer type alignment layer, the pencil hardness of the transfer type alignment layer is 3B or less, and the thickness of the transfer type alignment layer is 100 nm to 10000 nm, and the retardation film is calculated according to the following calculation formula ( A):

[In formula (A),
AL indicates the number of types of structural units derived from the polymerizable compound constituting the resin constituting the alignment layer constituting the retardation film,
Cwi indicates the content (mass%) of structural units derived from polymerizable compound i, based on all structural units derived from polymerizable compounds 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 possessed by 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,
Cwj indicates the content (mass%) of the structural units derived from the polymerizable liquid crystal compound j, based on 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 possessed by the polymerizable liquid crystal compound j constituting the retardation layer,
L _AL indicates the thickness (μm) of the alignment layer,
_LLC indicates the thickness (μm) of the retardation layer,
L _total indicates the sum of L _AL and L _LC ]
An optical laminate in which the amount N of polymerizable groups calculated by is 0.59 or less.

(1) Puncture elastic modulus (g/mm) = F (g)/S (mm)
The optical laminate according to claim 1, wherein the transfer type alignment layer has a thickness of 2.0 to 3.5 μm. The optical laminate according to claim 1 or 2, wherein the thickness of the retardation film is 3.5 to 30 μm. The optical laminate according to claim 1, further comprising a polarizing plate. The optical laminate further includes a front plate,
The optical laminate according to claim 4, wherein the front plate is arranged on a side of the polarizing plate opposite to the side on which the retardation film is laminated. The optical laminate according to claim 5, further comprising a touch sensor. A display device, wherein the optical laminate according to claim 1 is laminated on a display element.

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