TWI807029B - Optical laminate - Google Patents

Abstract

The objective of this invention is to provide an optical laminate which has a polarizing plate and a retardation film, and which can suppress generation of cracks even when it is subjected to thermal shock.

The optical laminate has a polarizing plate and a retardation film. When the retardation film is ruptured by pressing a tip of a piercing jig perpendicularly to the film surface, the piercing elastic modulus calculated by the following formula (1) using the stress F (g) applied to the retardation film from the tip of the piercing jig and the strain amount S (mm) of the retardation film is 50 g/mm or less.

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

Description

Optical laminate

The present invention relates to an optical laminate.

In recent years, video display devices typified by organic electroluminescence (hereinafter referred to as organic EL) display devices have rapidly become popular. An optical laminate having a circular polarizing plate with a polarizer and a retardation film or other optical functional layers is mounted on the organic EL display device.

Regarding retardation films for image display devices such as organic EL display devices, those formed by stretching conventional resin films or using liquid crystal compounds as materials have been proposed. As the demand for thinner image display devices becomes stronger, thinner retardation films and optical laminates equipped with such retardation films are also required (for example, refer to Patent Document 1).

[Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2017-102286

Such an optical layered body having a retardation film expands and shrinks due to temperature changes, and cracks originate from the retardation film. In particular, cracks are likely to occur when a severe 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 will be reduced.

The object of the present invention is to solve the above-mentioned problems by providing an optical layered body having a retardation film that can suppress the generation of cracks even in an environment subjected to severe temperature changes (thermal shock).

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

[1] An optical laminate having a retardation film, and when the retardation film is broken by pressing the front end of the puncture assisting tool perpendicular to the film surface, the puncture elastic modulus calculated by the following formula (1) using the stress F (g) applied to the retardation film from the front end of the puncture assisting tool and the deformation amount S (mm) of the retardation film is 50 g/mm or less.

(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 cured from a polymerizable liquid crystal compound.

[3] The optical layered body according to [2], wherein the retardation film further includes an alignment layer.

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

[5] The optical layered body according to [1], wherein the optical layered body further has a polarizing plate.

[6] The optical layered body according to [5], wherein the optical layered body further has a front plate, and the front plate is arranged on the viewing side of the polarizing plate.

[7] The optical layered body according to [6], wherein the optical layered body further has a touch sensor. The present invention also provides a display device as shown in the following [8].

[8] A display device in which the optical multilayer volume described in any one of [1] to [7] is laminated on a display element.

According to the present invention, there is provided an optical layered body having a retardation film and capable of suppressing the generation of cracks even in an environment where severe temperature changes occur.

1‧‧‧The first retardation film (retardation film)

2‧‧‧The second retardation film

3‧‧‧Polarizer

4‧‧‧Organic EL display element

5‧‧‧Front panel

6‧‧‧shading 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

Fig. 1 (a) to (c) is an example of the schematic cross-sectional view which shows the layer structure of the optical laminated body of this invention.

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

Fig. 3 is a schematic cross-sectional view showing the layer configuration of the optical laminates produced using Examples 1 to 6 and Comparative Examples 1 and 2 during a thermal shock test.

(Definitions of terms and symbols)

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

(1) Puncture elastic modulus

The puncture elastic modulus is a physical property value of the film defined by the stress F (g) applied to the film from the tip of the puncture aid when the tip of the puncture aid is pressed perpendicular to the film surface and the deformation amount S (mm) of the film before the hole is penetrated or broken. The puncture elastic modulus is expressed by the proportional constant between stress F and strain S (stress F/strain S).

The measurement of the puncture elastic modulus can be performed with a compression testing machine equipped with a dynamometer. Examples of the compression testing machine include the puncture testing machine "NDG5" manufactured by Kato-tech Co., Ltd., the portable compression testing machine "KES-G5", and the small tabletop testing machine "EZTest" of Shimadzu Corporation. From the stress-strain curve obtained using such a compression tester, the stress applied to the film at the time of fracture and the amount of deformation to the film before that can be measured.

The rupture of the membrane when the puncture aid is pressed also includes the case where a penetrating hole is generated in the membrane by the front end of the aid.

(2) Alignment layer

The alignment layer means a layer having the ability to restrict the molecular axis direction of the polymerizable liquid crystal compound forming the retardation layer to desired retardation characteristics. A layer (retardation layer) cured from a polymerizable liquid crystal compound is formed on the substrate via the alignment layer. The alignment layer includes an alignment layer containing an alignment polymer, a photo-alignment film, and a groove alignment layer that forms a concave-convex pattern or a plurality of grooves on the surface and aligns them.

(3) Vertical alignment

Vertical alignment means a state in which the direction of the molecular axis of the polymerizable liquid crystal compound forming the retardation layer is substantially perpendicular to the lamination plane of each layer constituting the optical layered body. A positive type C layer is mentioned as a typical example of the retardation layer which shows vertical alignment.

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

"nx" refers to the refractive index in the direction where the in-plane refractive index is the largest (that is, the direction of the slow axis), "ny" refers to the refractive index in the direction perpendicular to the slow axis in the plane, and "nz" refers to the refractive index in the thickness direction.

(5) In-plane phase difference

The in-plane retardation value (Re[λ]) refers to the in-plane retardation value of the film at the wavelength λ (nm) at 23°C. Re[λ] can be obtained by Re[λ]=(nx-ny)×d when the thickness of the film is d (nm).

(6) Phase difference value in thickness direction

The in-plane retardation value (Rth[λ]) refers to the retardation value in the thickness direction of the film at the wavelength λ (nm) at 23°C. Rth[λ] can be obtained by Rth[λ]=((nx+ny)/2-nz)×d when the thickness of the film is d (nm).

<Optical laminate>

The optical layered body of the present invention has a retardation film, and the puncture elastic modulus of the retardation film is 50 g/mm or less. Moreover, the said retardation film has a retardation layer. The retardation layer preferably has a layer composed of a composition containing a polymerizable liquid crystal compound. The layer composed of a composition containing a polymerizable liquid crystal compound specifically refers to a layer formed by curing a polymerizable liquid crystal compound. In this specification, the layer giving a phase difference of λ/2, the layer giving a phase difference of λ/4 (positive type A layer), and the positive type C layer may be collectively referred to as retardation layers. In addition, the retardation film may contain an alignment layer described later.

An example of the layer constitution of the optical layered body of the present invention will be described below with reference to FIG. 1 . The optical laminate 100 shown in FIG. 1( a ) has the following layer structure: a retardation layer 10 is provided on one side of the alignment layer 11 , and an adhesive layer 12 is provided on the other side of the alignment layer 11 . The adhesive layer 12 may be an adhesive layer used to be attached 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 layer structure in which a second retardation film 2 is laminated via an adhesive layer 13 on the opposite side of the phase difference layer 10 in FIG. 1 (a) to the side where the alignment layer 11 is laminated. The adhesive layer 12 may be an adhesive layer for bonding to an organic EL display element or the like, as in Fig. 1(a). In this optical layered body 101 , the first retardation film 1 is composed of a retardation layer 10 and an alignment layer 11 .

The optical laminate 102 shown in FIG. 1 (c) has a layer structure in which a polarizing plate 3 is laminated via an adhesive layer or an adhesive layer on the side opposite to the side where the first retardation film 1 is laminated on the second retardation film 2 in FIG. 1 (b). Here, the adhesive layer or the adhesive layer for laminating the second retardation film 2 and the polarizing plate 3 is not shown in the drawings. The adhesive layer 12 can be an adhesive layer for bonding to an organic EL display element, a touch sensor, etc. similarly to FIG. 1 (a), (b). In this optical layered body 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 layered body of the present invention may have two or more retardation films. When there are multiple retardation films in the optical laminate, at least one retardation film has a puncture modulus of 50 g/mm or less. However, from the viewpoint of suppressing cracks caused by temperature changes, it is preferable that all the retardation films contained in the optical laminate have a puncture modulus of 50 g/mm or less.

When the retardation layer of the retardation film is used as a layer composed of a composition containing a polymerizable liquid crystal compound (a layer cured from a polymerizable liquid crystal compound), it is preferable because it is easy to set the puncture elastic modulus of the present invention to 50 g/mm or less. In addition, the retardation film may have an alignment layer for aligning the polymerizable liquid crystal compound. Also, in the manufacturing stage, it may further have a substrate supporting the alignment layer.

The polymerizable liquid crystal compound is a compound having a polymerizable group, and is a compound capable of becoming a liquid crystal state. The polymerizable liquid crystal compound is polymerized by the reaction of the polymerizable groups of the polymerizable liquid crystal compound to harden the polymerizable liquid crystal compound.

The layer system cured from the polymerizable liquid crystal compound is, for example, formed on the alignment layer provided on the substrate. The aforementioned substrate has the function of supporting the alignment layer, and may be a strip-shaped substrate. This substrate can function as a release support to support a retardation layer or an alignment layer for transfer. In addition, it is preferable that the surface has a peelable adhesive force. The aforementioned substrate may be a film made of the following resins: thermoplastic resins with light transmission (preferably optically transparent), for example: polyolefin resins such as chain polyolefin resins (polypropylene resins, etc.), cyclic polyolefin resins (norbornene resins, etc.); cellulose resins such as cellulose triacetate and cellulose diacetate; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate resins; (Meth)acrylic resin of methyl ester resin; polystyrene resin; polyvinyl chloride resin; acrylonitrile-butadiene-styrene resin; acrylonitrile-styrene resin; polyvinyl acetate resin; polyvinylidene chloride resin; polyamide resin; polyketal resin; modified polyphenylene ether resin; Resin; maleimide resin, etc.

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

In addition, the substrate can be given various anti-blocking treatments. The anti-blocking treatment includes, for example, easy-adhesive treatment, treatment such as kneading filler, embossing (knurling treatment), and the like. By applying such an anti-blocking treatment to the base material, it is possible to effectively prevent the adhesion between the base materials when the base material is wound, that is, to prevent the blocking, and to manufacture an optical film with high productivity.

The layer formed by hardening the polymerizable liquid crystal compound is formed on the base material through the alignment layer. That is to say, the base material and the alignment layer are laminated sequentially, and the laminated layer hardened by the polymerizable liquid crystal compound is on the aforementioned alignment layer.

In addition, the alignment layer is not limited to a vertical alignment layer, and may also be an alignment layer that aligns the molecular axes of the polymerizable liquid crystal compound horizontally, or an alignment layer that aligns the molecular axes of the polymerizable liquid crystal compound obliquely. The alignment layer preferably has solvent resistance that will not be dissolved by coating of a composition containing a polymerizable liquid crystal compound described later, and heat resistance in heat treatment for removing the solvent or aligning the liquid crystal compound. The alignment layer includes an alignment layer containing an alignment polymer, a photo-alignment film, and a groove alignment layer that forms a concave-convex pattern or a plurality of grooves on the surface and aligns them. The thickness of the alignment layer is generally in the range of 10 nm to 10000 nm.

In addition, the alignment layer has a function of supporting the retardation layer, and can function as a release support. The phase difference layer for transfer can be supported, and even the surface can have adhesive force to the extent that it can be peeled off.

The resin used for the alignment layer is a resin polymerized from a polymerizable compound. The polymerizable compound is a compound having a polymerizable group, and is usually a non-liquid-crystalline polymerizable non-liquid-crystalline compound that does not become a liquid-crystalline state. The polymerizable compound is polymerized by the reaction of the polymerizable groups of the polymerizable compound to form a resin. Such a resin is not particularly limited as long as it is used as an alignment layer for aligning the polymerizable liquid crystal compound in the formation stage of the retardation layer and is not included in the retardation film, as long as it is used as a well-known alignment layer material, and a cured product obtained by curing a conventionally known monofunctional or polyfunctional (meth)acrylate monomer under a polymerization initiator can be used. Specifically, examples of (meth)acrylate-based monomers include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono-2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, and benzyl acrylate. , tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, methacrylic acid, urethane acrylate, etc. In addition, the resin may be one of these or a mixture of two or more.

After forming the retardation layer, the alignment layer can be peeled and removed together with the substrate before and after the step of laminating with other optical films.

Moreover, an alignment layer may be contained in a phase difference film for the purpose of improving the peelability with a base material, and providing film strength to a phase difference film. When the retardation film includes an alignment layer, the resin used for the alignment layer is preferably a cured product obtained by curing a monofunctional or bifunctional (meth)acrylate monomer, an imide monomer, or a vinyl ether monomer from the viewpoint of a puncture elastic modulus of 50 g/mm or less.

Monofunctional (meth)acrylate monomers include alkyl (meth)acrylates with 4 to 16 carbons, beta carboxyalkyl (meth)acrylates with 2 to 14 carbons, alkylated phenyl (meth)acrylates with 2 to 14 carbons, methoxypolyethylene glycol (meth)acrylates, phenoxypolyethylene glycol (meth)acrylates, and isobornyl (meth)acrylates. Bifunctional (meth)acrylate monomers include 1,3-butanediol Di(meth)acrylate; 1,3-Butanediol di(meth)acrylate; 1,6-Hexanediol di(meth)acrylate; Ethylene glycol di(meth)acrylate; Diethylene glycol di(meth)acrylate; Neopentyl glycol di(meth)acrylate; Triethylene glycol di(meth)acrylate; Tetraethylene glycol di(meth)acrylate; Polyethylene glycol diacrylate; Acrylates; Propoxylated neopentyl glycol di(meth)acrylate; Epoxylated neopentyl glycol di(meth)acrylate and 3-methylpentanediol di(meth)acrylate, etc.

Moreover, examples of the imide-based resin obtained by curing an imide-based monomer include polyamide, polyimide, and the like. In addition, the imide-based resin may be one or a mixture of two or more of these.

Moreover, the resin forming the alignment layer may also contain monomers other than monofunctional or bifunctional (meth)acrylate monomers, imide monomers, and vinyl ether monomers, but the content ratio of monofunctional or bifunctional (meth)acrylate monomers, imide monomers, and vinyl ether monomers in the total monomers may be 50% by weight or more, preferably 55% by weight or more, more preferably 60% by weight or more.

When the retardation film contains an alignment layer, the thickness of the alignment layer is usually in the range of 10nm to 10000nm. When the alignment of the retardation layer is in-plane aligned with the film surface, the thickness of the alignment layer is preferably 10nm to 1000nm. When the alignment layer is vertically aligned with the film surface, it is preferably 100nm to 10000nm. When the thickness of the alignment layer is within the above-mentioned range, the peelability of the base material can be improved and moderate film strength can be provided.

The type of polymerizable liquid crystal compound used in this embodiment is not particularly limited, but can be classified into rod-shaped (rod-shaped liquid crystal compound) and discotic type (disco-shaped liquid crystal compound, discotic liquid crystal compound) according to its shape. In addition, there are low-molecular-weight types and high-molecular-weight types, respectively. In addition, a polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics/Phase Transfer Dynamics, Masao Doi, p. 2, Iwanami Shoten, 1992).

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

In addition, as rod-like liquid crystal compounds, for example, those described in claim 1 of JP-A-11-513019 can be used suitably. As the discotic liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 or paragraphs [0013]-[0108] of JP-A-2010-244038 can be used suitably.

Two or more kinds of polymerizable liquid crystal compounds may be used in combination. In this case, at least one type has two or more polymerizable groups in the molecule. That is, the layer cured from the aforementioned polymerizable liquid crystal compound is preferably a layer formed by polymerizing and fixing a liquid crystal compound having a polymerizable group. In this case, it is not necessary to exhibit liquid crystallinity after layer formation.

The polymerizable liquid crystal compound has a polymerizable group capable of a polymerization reaction. The polymerizable group is preferably a functional group capable of addition polymerization reaction, such as a polymerizable ethylenically unsaturated group or a ring polymerizable group. More specifically, the polymerizable group includes, for example, a (meth)acryl group, a vinyl group, a styryl group, an allyl group, and the like. Among them, a (meth)acryl group is preferred. In addition, a (meth)acryl group is a concept including both a methacryl group and an acryl group.

The layer cured from the polymerizable liquid crystal compound can be formed by, for example, coating the alignment layer with a composition containing the polymerizable liquid crystal compound and irradiating active energy rays, as will be described later. The aforementioned composition may contain components other than the aforementioned polymerizable liquid crystal compound. For example, the aforementioned composition preferably contains a polymerization initiator. The polymerization initiator used is selected according to the form of the polymerization reaction, for example, a thermal polymerization initiator or a photopolymerization initiator. Examples of photopolymerization initiators include α-carbonyl compounds, ketol ethers, α-hydrocarbon-substituted aromatic ketol compounds, polynuclear quinone compounds, combinations of triaryl imidazole dimers and p-aminophenyl ketones, and the like. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass relative to the total solids in the aforementioned coating solution.

The term "hardened" in the present invention refers to a state in which a single layer can exist independently without deformation or flow, and the puncture modulus of the formed layer is usually 3 g/mm or more.

In addition, from the viewpoint of the uniformity of the coating film and the strength of the film, the aforementioned composition may contain a polymerizable monomer. Examples of polymerizable monomers include radically polymerizable or cationically polymerizable compounds. Among them, polyfunctional radically polymerizable monomers are preferred.

In addition, the polymerizable monomer system is preferably one that can be copolymerized with the above-mentioned polymerizable liquid crystal compound. The amount of the polymerizable monomer used is preferably from 1 to 50% by mass, more preferably from 2 to 30% by mass, relative to the total mass of the polymerizable liquid crystal compound.

In addition, from the viewpoint of the uniformity of the coating film and the strength of the film, the aforementioned composition may contain a surfactant. Surfactants include conventionally known compounds. Among them, fluorine-based compounds are particularly preferred.

In addition, the aforementioned composition may contain a solvent, preferably an organic solvent. Organic solvents include, for example, amides (such as N,N-dimethylformamide), azolides (such as dimethylsulfoxide), heterocyclic compounds (such as pyridine), hydrocarbons (such as benzene, hexane), alkyl halides (such as chloroform, methylene chloride), esters (such as methyl acetate, ethyl acetate, butyl acetate), ketones (such as acetone, methyl ethyl ketone), ethers (such as tetrahydrofuran, 1,2-dimethoxyethane). Among them, alkyl halides and ketones are preferred. In addition, two or more organic solvents may be used in combination.

In addition, the aforementioned composition may contain vertical alignment promoters such as vertical alignment agents on the polarizer interface side and vertical alignment agents on the air interface side, and various alignment agents such as horizontal alignment accelerators on the polarizer interface side and horizontal alignment agents on the air interface side. In addition, the aforementioned composition may contain an adhesion improving agent, a plasticizer, a polymer, and the like in addition to the aforementioned components.

The active energy rays include ultraviolet rays, visible light, electron beams, and X-rays, preferably ultraviolet rays. The light sources of the above-mentioned active energy rays include, for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources that emit light in the wavelength range of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, etc.

The irradiation intensity of ultraviolet rays is usually 100 mW/cm ² to 3,000 mW/cm ² when using ultraviolet B waves (wavelength range of 280 to 310 nm). The intensity of ultraviolet irradiation 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 second to 10 minutes, preferably 0.1 second to 5 minutes, more preferably 0.1 second to 3 minutes, and more preferably 0.1 second to 1 minute.

Ultraviolet rays can be irradiated in one or multiple times. Although it varies depending on the polymerization initiator used, the cumulative light intensity at a wavelength of 365nm is preferably at least 700mJ/cm ² , more preferably at least 1,100mJ/cm ² , and more preferably at least 1,300mJ/cm ² . It is assumed that the above-mentioned integrated light quantity improves the polymerization rate of the polymerizable liquid crystal compound constituting the retardation film, which is advantageous to the improvement of heat resistance. The cumulative light intensity at a wavelength of 365 nm is preferably 2,000 mJ/cm ² or less, more preferably 1,800 mJ/cm ² or less. There is a possibility that the retardation film may be colored if the accumulated light quantity is set as above. In addition, after the irradiation of ultraviolet rays, a cooling step may be provided. The cooling temperature can be set to, for example, 20°C or lower, and can be set to 10°C or lower. The cooling time may 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. Also, the thickness of the retardation layer is preferably 10 μm or less, more preferably 5 μm or less. In addition, the above-mentioned upper limit and lower limit may be combined arbitrarily. Sufficient durability can be acquired as the thickness of a retardation layer is more than the said lower limit. When the thickness of the retardation layer is at most the aforementioned upper limit, it contributes to thinning of the optical layered body. The thickness of the retardation layer can be adjusted to obtain desired in-plane and thickness direction retardation values for a layer imparting a retardation of λ/4, a layer imparting a retardation of λ/2, or a positive type C layer.

The retardation film may contain a plurality of retardation layers each having a different retardation characteristic. The retardation layers may be laminated via an adhesive or an adhesive, or a composition containing a polymerizable liquid crystal compound may be coated on the surface of the formed retardation layer and cured.

When the retardation film is formed only of a retardation layer formed by hardening a polymerizable liquid crystal compound, it is preferable because the puncture elastic modulus can be greatly reduced and cracks caused by thermal shock can be suppressed. When the retardation film is formed only from a retardation layer formed by hardening a polymerizable liquid crystal compound, the puncture elastic modulus of the retardation film may be, for example, less than 40 g/mm or less than 35 g/mm, preferably less than 30 g/mm, more preferably less than 25 g/mm, more preferably less than 15 g/mm, and usually more than 3 g/mm. From the viewpoint of maintaining film strength, the puncture elastic modulus is preferably 7 g/mm or more.

On the other hand, when the phase differential membrane system is formed by the phase differential layer of the polymerization LCD compound hardening, from the perspective of inhibiting cracks caused by temperature changes and maintaining moderate substrates and membrane strength, the lower limit of the puncture elasticity of the phase differential membrane is more than 15g/mm. It is less than 50g/mm, it is better to be less than 40g/mm, and better is less than 30g/mm (usually more than 5g/mm).

As mentioned above, the retardation film of the present invention may consist of retardation layer only, or consist of retardation layer and alignment layer, but the retardation film is preferably one whose polymeric base N shown in the following calculation formula (A) is 0.67 or less or even 0.64 or less

The polymerizable group N is usually at least 0.01, preferably at least 0.03.

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

Cwi represents the content (% by mass) of the constituent units derived from the polymerizable compound i based on the total constituent units derived from the polymerizable compound in the resin constituting the alignment layer, Mi represents the molecular weight of the polymerizable compound i constituting the alignment layer, and Ni represents the number of polymerizable groups contained in the polymerizable compound j constituting the alignment layer.

When the retardation layer is a layer cured from a polymerizable liquid crystal compound, LC represents the number of types of constituent units derived from the polymerizable liquid crystal compound constituting the retardation layer.

Cwj represents the content (mass %) of the constituent units derived from the polymerizable liquid crystal compound j based on the total constituent units derived from the polymerizable liquid crystal compound in the retardation layer, Mj represents the molecular weight of the polymerizable liquid crystal compound j constituting the retardation layer, and Nj represents the number of polymerizable groups contained in the polymerizable liquid crystal compound j constituting the retardation layer.

L _AL represents the thickness (μm) of the alignment layer, and L _LC represents the thickness (μm) of the retardation layer. L _total represents the sum of L _AL and L _LC .

In the environment where a display device laminated with an optical laminate is used, if the temperature changes, expansion and contraction will occur in the retardation film, other optical films, adhesives, and adhesive layers constituting the optical laminate. The effects of dimensional changes due to expansion and contraction of other components tend to concentrate on the retardation film. Compared with the dimensional changes of other components caused by temperature changes, the retardation film becomes unable to conform, 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 cured from a polymerizable liquid crystal compound. Especially when the phase difference film is formed by a phase difference layer or a phase difference layer and an alignment layer, and when the phase difference layer or the alignment layer is directly laminated with an adhesive layer or an adhesive layer, cracks are likely to occur. When the alignment of the phase difference layer has vertical alignment like a positive C layer, this tendency becomes obvious.

In the optical layered body of this case, by setting the puncture elastic modulus of the retardation film as its constituent element to be 50 g/mm or less, the retardation film can comply with the dimensional changes of other members caused by the above-mentioned temperature change, and even if the retardation film or the optical layered body that is prone to cracks is used, the occurrence of the cracks can be appropriately suppressed.

The optical layered body of the present invention may have two or more retardation films. When the optical laminate contains two retardation films, the two layers are preferably a layer giving a retardation of λ/4 and a positive type C layer, or a layer giving a retardation of λ/4 and a layer giving a retardation of λ/2. When the optical laminate includes two retardation films, the retardation layers of the respective retardation films can be laminated via an adhesive layer or an adhesive layer. From the viewpoint of thinning the optical layered body, the thickness of the retardation film in which a plurality of layers is laminated is preferably from 3 to 30 μm, more preferably from 5 to 25 μm.

In the composition of the optical laminate, there are two or more retardation films, and when at least one of the retardation films has a retardation layer cured from a polymerizable liquid crystal compound and exhibits vertical alignment, cracks tend to be more likely to occur due to thermal shock. In particular, when retardation films are laminated through an active energy ray-curable adhesive, and the storage elastic modulus of the adhesive layer is 3000 MPa or more, generation of cracks becomes conspicuous. Regarding the combination of retardation characteristics when the optical laminate has two types of retardation films, for example, the retardation layer is a combination of a retardation film having a layer imparting a retardation of λ/4 and a retardation film having a layer imparting vertical alignment. Even in the optical layered body constituted in this way, the occurrence of cracks can be effectively suppressed by setting the puncture modulus of the retardation film within the range defined in this application.

When an alignment layer is included in the retardation film, evaluation of abrasion resistance such as pencil hardness or steel wool hardness of the alignment layer can be used as an index for suppressing cracks caused by thermal shock.

For example, pencil hardness is obtained in accordance with JIS K 5600-5-4:1999, and indicates the hardest pencil hardness that does not cause scratches when scratched with pencils of each hardness. When the pencil hardness of the alignment layer is 3B or less, it is preferable because generation of cracks due to thermal shock can be suppressed.

The hardness of steel wool used as another index is, for example, using a steel wool testing machine (manufactured by Daiei Seiki Co., Ltd.) to contact the surface of the test object with a clean room wiping cloth (BEMCOT AZ-8, manufactured by Asahi Kasei Co., Ltd.) with a load of 500 g, and perform an abrasion test of 4 times at a speed of 40 r/min, and then express it by the number of scratches confirmed visually. In terms of suppressing the generation of cracks caused by thermal shock, the number of scratches measured by the steel wool test on the alignment layer is preferably 4 or more, more preferably 8 or more.

From the viewpoint of operability 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, preferably 20 or less, more preferably 10 or less.

The photoelastic coefficient of the retardation film is preferably from 3×10 ^-13 to 100×10 ^-13 Pa ^-1 , more preferably from 5×10 ^-13 to 70×10 ^-13 Pa ^{-1 , more preferably from 15×10 -13 to 60×10 -13 Pa -1 , even more} preferably from 20×10 ^-13 to 60×10 ^-13 Pa ^-1 .

In addition, the photoelastic coefficient can be calculated from the slope of the function of the stress and the retardation value by measuring the retardation value (23°C/wavelength 550nm) at the center of the specimen, for example, when both ends of the specimen (dimensions 1 cm × 10 cm) are clamped by a retardation measuring device KOBRA-WPR (manufactured by Oji Scientific Instruments Co., Ltd.) and a stress (0.5 N to 3 N) is applied.

The optical laminate may have layers other than those shown in FIG. 1 . The additional layers that the optical laminate can have include optical functional layers such as front panels, light-shielding patterns, and polarizers, or adhesive layers or adhesive layers for laminating layers with other optical functional layers, touch sensors, and the like. The front plate may be disposed on the opposite side of the polarizing plate 3 to the side where the retardation film is laminated. The light-shielding pattern may be formed on the surface on the polarizing plate side in the front panel. The light-shielding pattern can be formed on the frame (non-display area) of the image display device, so that the wiring of the image display device is not observed by the user. The touch sensor can be laminated on the optical laminate through the adhesive layer 12 .

The shape of the main surface of the optical layered body may be substantially rectangular. The so-called main surface means the surface corresponding to the display surface having the widest area. The term "substantially rectangular" refers to the following: at least one of the four corners (corners) is cut into an obtuse shape or a shape with rounded corners, or a part of the end surface perpendicular to the main surface has a concave part (notch) that is recessed in the direction of the surface, or a part of the main surface has a perforation that is pierced into a shape such as a circle, an ellipse, a polygon, or a combination thereof.

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

The thickness of the optical layered body is usually 50 to 500 μm, but from the viewpoint of thinning, it is preferably 150 μm or less, more preferably 105 μm or less, but when the thickness of the optical layered body is 105 μm or less and thermal shock occurs, cracks starting from the retardation film tend to spread to the entire optical layered body.

Even with such a thin-film optical laminate, by setting the puncture modulus of the retardation film within the range specified in this document, the occurrence of cracks due to temperature changes can be appropriately suppressed.

From the viewpoint of suppressing cracks caused by thermal shock, it is preferable that the retardation film of this application should reduce the amount of curling in the state attached to the base material. The amount of curl can be measured by cutting the layer structure with the base material into a square of 10 cm×10 cm, and adjusting the humidity at 55% at 23° C. 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 (eg 20 μm), the average value of the curl amount on four sides is preferably 10 mm or less, more preferably 5 mm or less.

<Polarizer>

In the present invention, the term "polarizing plate" refers to a single type of polarizing plate or a laminate composed of a protective film attached to at least one side of the polarizing plate. The protective film included in the polarizing film may have surface treatment layers 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 via an adhesive layer or an adhesive layer, for example. The components included in the polarizing plate are as follows.

(1) Polarizer

The polarizer included in the polarizing plate can be an absorption type polarizer that absorbs linearly polarized light having a vibration plane parallel to its absorption axis and transmits linearly polarized light having a vibration plane perpendicular to the absorption axis (parallel to the transmission axis). As the polarizer included in the first layer, a polarizer in which a uniaxially stretched polyvinyl alcohol-based resin film is adsorbed and aligned with a dichroic dye can be suitably used. A polarizer can be produced, for example, by a method including: uniaxially stretching a polyvinyl alcohol-based resin film; dyeing the polyvinyl alcohol-based resin film with a dichroic dye to absorb the dichroic dye; treating the polyvinyl alcohol-based resin film adsorbed with the dichroic dye with a cross-linking liquid such as boric acid aqueous solution; and washing with water after the treatment with the cross-linking liquid.

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. Polyvinyl acetate-based resins include copolymers with other monomers that can be copolymerized with vinyl acetate, in addition to polyvinyl acetate that is a homopolymer of vinyl acetate. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides with ammonium groups.

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

The degree of saponification of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, for example, polyvinyl formaldehyde or polyvinyl acetal modified with aldehydes may be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000. The average degree of polymerization of a polyvinyl alcohol-type resin can be calculated|required based on JISK6726.

Those obtained by forming such a polyvinyl alcohol-based resin into a film are used as a base film of a polarizer (polarizer). The method of forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a known method can be employed. The thickness of the polyvinyl alcohol-based embryonic film is not particularly limited, but in order to reduce the thickness of the polarizer to 15 μm or less, it is preferably 5 to 35 μm. More preferably, it is 20 μm or less.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing of the dichroic dye, simultaneously with dyeing, or after dyeing. When performing uniaxial stretching after dyeing, this uniaxial stretching may be performed before or during crosslinking treatment. Also, uniaxial stretching may be performed in these plural steps.

During uniaxial stretching, uniaxial stretching can be performed between rollers with different peripheral speeds, or uniaxial stretching can be performed with hot rollers. In addition, the uniaxial stretching may be a dry stretching in which stretching is carried out in the atmosphere, or a wet stretching in which a polyvinyl alcohol-based resin film is stretched in a state in which the polyvinyl alcohol-based resin film is swollen using a solvent or water. The elongation ratio is usually 3 to 8 times.

A method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye is, for example, a method of immersing the film in an aqueous solution containing a dichroic dye. As the dichroic dye, iodine or a dichroic organic dye is used. In addition, the polyvinyl alcohol-based resin film is preferably subjected to a dipping treatment in water before the dyeing treatment.

The cross-linking treatment after dyeing by a dichroic dye generally employs a method of immersing a dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. When using iodine as a 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, more preferably 10 μm or less, particularly preferably 8 μm or less. The thickness of the polarizer is usually at least 2 μm, preferably at least 3 μm.

Polarizers are, for example, those described in JP-A-2016-170368, and those in which dichroic dyes are aligned can be used in cured films polymerized from liquid crystal compounds. Dichroic dyes can be those that absorb in the wavelength range of 380 to 800 nm, preferably organic dyes. As a dichroic dye, an azo compound is mentioned, for example.

The liquid crystal compound is a liquid crystal compound that can be polymerized directly under alignment, and it may have a polymerizable group in the molecule. Moreover, as described in WO2011/024891, a polarizer can also be formed with the dichroic dye which has liquid crystallinity.

The shrinkage force of the polarizer is preferably at most 2.0 N/2mm, more preferably at most 1.8 N/2mm, and more preferably at most 1.5 N/2mm.

(2) Protective film

The polarizing plate of the present invention may have a protective film on at least one side of the polarizing plate. When there is a protective film between the polarizer and the retardation film, it is preferable to have negative birefringence. Here, negative birefringence means that a slow axis appears in the direction perpendicular to the extending direction of the resin. It is considered that because the retardation film uses a retardation layer having positive birefringence, a retardation different from that of the retardation film accompanying thermal shrinkage of the polarizer appears, and the color change becomes smaller. Here, positive birefringence means that the slow axis appears in the direction parallel to the extending direction of the retardation film.

The protective film laminated on the polarizer can be a film made of the following resins: a light-transmitting (preferably optically transparent) thermoplastic resin, such as: polyolefin resins such as chain polyolefin resins (polypropylene resins, etc.), cyclic polyolefin resins (norbornene resins, etc.); cellulose resins such as cellulose triacetate and cellulose diacetate; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate resin; (meth)acrylic resin such as methyl methacrylate resin; polystyrene resin; polyvinyl chloride resin; acrylonitrile-butadiene-styrene resin; acrylonitrile-styrene resin; polyvinyl acetate resin; polyvinylidene chloride resin; polyamide resin; polyketal resin; modified polyphenylene ether resin; Resin; polyimide resin; maleimide resin, etc.

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

The (meth)acrylic resin is a resin mainly composed of a compound having a (meth)acryl group as a monomer. Specific examples of (meth)acrylic resins include, for example: poly(meth)acrylate such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymer; methyl methacrylate-(meth)acrylate copolymer; methyl methacrylate-acrylate-(meth)acrylic acid copolymer; (meth)methyl acrylate-styrene copolymer (MS resin, etc.); ester copolymers, etc.). It is preferable to use a polymer mainly composed of poly(meth)acrylate C _1-6 alkyl ester, more preferably a methyl methacrylate resin mainly composed of methyl methacrylate (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, 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, more preferably 5 nm or less, particularly preferably 3 nm or less, most preferably 1 nm or less. When the retardation value in the plane and the retardation value in the thickness direction fall within such a range, the color change at the time of a heat resistance test can be suppressed without impairing the characteristic of a retardation film. In order to set the in-plane retardation value and the retardation value in the thickness direction within such a range, it can be obtained, for example, using a (meth)acrylic resin having a glutarimide structure described later.

The aforementioned (meth)acrylic resin may preferably have a structural unit exhibiting positive birefringence within the range of having negative birefringence. If there are structural units exhibiting positive birefringence and structural units exhibiting negative birefringence, the abundance ratio can be adjusted to suppress the retardation of the (meth)acrylic resin film and obtain a (meth)acrylic resin film with low retardation. Structural units exhibiting positive birefringence include, for example, structural units constituting lactone rings, polycarbonates, polyvinyl alcohol, cellulose acetate, polyesters, polyarylates, polyimides, polyolefins, etc., and structural units represented by general formula (1) described later. Structural units exhibiting negative birefringence include, for example, structural units derived from styrene-based monomers, maleimide-based monomers, etc., structural units of polymethyl methacrylate, structural units represented by general formula (3) described later, and the like.

As the (meth)acrylic resin, it is preferable to use a (meth)acrylic resin having a lactone ring structure or a glutarimide structure. A (meth)acrylic resin having a lactone ring structure or a glutarimide structure is excellent in heat resistance. More preferably, it is a (meth)acrylic resin having a glutarimide structure. If a (meth)acrylic resin having a glutarimide structure is used, as described above, a (meth)acrylic resin film having low moisture permeability and a small retardation and ultraviolet transmittance can be obtained. (Meth)acrylic resins having a glutarimide structure (hereinafter also referred to as glutarimide resins) are described in, for example, JP 2006-309033, JP 2006-317560, JP 2006-328329, JP 2006-328334, JP 2006-337491 Japanese Patent Laid-Open No. 2006-337492, Japanese Patent Laid-Open No. 2006-337493, Japanese Patent Laid-Open No. 2006-337569, Japanese Patent Laid-Open No. 2007-009182, and Japanese Patent Laid-Open No. 2009-161744. These descriptions are incorporated in this specification as a reference.

Preferably, the glutarimide resin includes a structural unit represented by the following general formula (1) (hereinafter also referred to as a glutarimide unit) and a structural unit represented by the following general formula (2) (hereinafter also referred to as a (meth)acrylate unit).

In formula (1), R ¹ and R ² are independently hydrogen or an alkyl group having 1 to 8 carbons, and R ³ is a substituent containing hydrogen, an alkyl group having 1 to 18 carbons, a cycloalkyl group having 3 to 12 carbons, or an aromatic ring having 5 to 15 carbons. In formula (2), R ⁴ and R ⁵ are independently hydrogen or an alkyl group having 1 to 8 carbons, and R ⁶ is a substituent containing hydrogen, an alkyl group having 1 to 18 carbons, a cycloalkyl group having 3 to 12 carbons, or an aromatic ring having 5 to 15 carbons.

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

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

In the above general formula (1), preferably, ^R1 and ^R2 are independently hydrogen or methyl, ^R3 is hydrogen, methyl, butyl, or cyclohexyl, and more preferably, ^R1 is methyl, ^R2 is hydrogen, and ^R3 is methyl.

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

The glutarimide unit can be formed by imidating the (meth)acrylate unit represented by the above general formula (2). In addition, the glutarimine unit can also be formed by imidating the following: 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, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, fumaric acid, methylmaleic acid, and other α,β-ethylenically unsaturated carboxylic acids, and the like.

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

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

The above-mentioned glutarimide resin preferably contains styrene, α-methylstyrene, etc. as the aromatic vinyl unit represented by the above general formula (3), and more preferably contains styrene. By having such an aromatic vinyl unit, the positive birefringence of the glutarimide structure is reduced and a (meth)acrylic resin film having a further low 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 different types of R ⁷ and R ⁸ .

The content of the above-mentioned glutarimide unit in the above-mentioned glutarimide resin is preferably changed according to, for example, the structure of R ³ . The content of the glutarimide unit is based on the total structural units of the glutarimide resin, preferably 1% by weight to 80% by weight, more preferably 1% by weight to 70% by weight, more preferably 1% by weight to 60% by weight, particularly preferably 1% by weight to 50% by weight. When the content of the glutarimide unit is within such a range, a (meth)acrylic resin film having excellent heat resistance and low retardation can be obtained.

The content of the said aromatic vinyl unit in the said glutarimide resin can be suitably set according to the objective or desired characteristic. Depending on the application, the content of aromatic vinyl units can also be 0. When the aromatic vinyl unit is contained, its content is based on the glutarimide unit of the glutarimide resin, preferably 10% by weight to 80% by weight, more preferably 20% by weight to 80% by weight, more preferably 20% by weight to 60% by weight, and most preferably 20% by weight to 50% by weight. When the content of the aromatic vinyl unit is within such a range, a (meth)acrylic resin film having a low retardation and excellent heat resistance and mechanical strength can be obtained.

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

The said (meth)acrylic-type resin film may contain arbitrary appropriate additives according to the purpose. Examples of additives include: antioxidants such as hindered phenols, phosphorus, and sulfur; stabilizers such as light-resistant stabilizers, ultraviolet absorbers, weather-resistant stabilizers, and heat stabilizers; reinforcements such as glass fibers and carbon fibers; near-infrared absorbers; flame retardants such as ginseng (dibromopropyl) phosphate, triallyl phosphate, and antimony oxide; Modifier; plasticizer; lubricant; phase difference reducer, etc. The type, combination, content, etc. of the additives to be contained can be appropriately set according to the purpose or desired characteristics.

The method for producing the above-mentioned (meth)acrylic resin film is not particularly limited. For example, the (meth)acrylic resin, ultraviolet absorber, and other polymers or additives may be sufficiently mixed by any appropriate mixing method to form a thermoplastic resin composition in advance and then form the film. Alternatively, the (meth)acrylic resin, ultraviolet absorber, and other polymers or additives may be formed into different solutions and then mixed to form a uniform liquid mixture before forming a film.

When producing the above-mentioned thermoplastic resin composition, for example, the above-mentioned film raw materials are pre-blended with any appropriate mixer such as an OM mixer, and then the obtained mixture is extruded and kneaded. At this time, the mixer used for extrusion kneading is not particularly limited, and any appropriate mixer such as an extruder such as a single-screw extruder or a twin-screw extruder, or a pressure kneader can be used.

Examples of the method of forming the film include any appropriate film forming methods such as solution casting (solution casting), melt extrusion, calendering, and compression molding. A melt extrusion method is preferred. Since the melt extrusion method does not use a solvent, it can reduce the manufacturing cost or the burden on the global environment or the working environment caused by the solvent.

Examples of the above-mentioned melt extrusion method include a T-die method, blow molding method, and the like. The forming temperature is preferably from 150 to 350°C, more preferably from 200 to 300°C.

When forming a film by the above-mentioned T-die method, a T-die can be attached to the front end of a known single-screw extruder or two-screw extruder, and the extruded film can be wound to obtain a roll-shaped film. At this time, uniaxial stretching can also be performed by appropriately adjusting the temperature of the winding reel and applying stretching in the extrusion direction. Also, by stretching the film in a direction perpendicular to the extrusion direction, simultaneous biaxial stretching, sequential biaxial stretching, and the like can also be performed.

As long as the above-mentioned desired phase difference can be obtained, the above-mentioned (meth)acrylic resin film may be either an unstretched film or a stretched film. When 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 stretching temperature is preferably around the glass transition temperature of the thermoplastic resin composition of the film raw material, specifically, it is preferably in the range of (glass transition temperature -30°C) to (glass transition temperature +30°C), more preferably (glass transition temperature -20°C) to (glass transition temperature +20°C). When the stretching temperature is lower than (glass transition temperature -30° C.), the haze of the obtained film may increase, or the film may be cracked or split, and a predetermined stretching ratio may not be obtained. Conversely, when the stretching temperature exceeds (glass transition temperature + 30°C), the thickness unevenness of the obtained film will become larger, or the mechanical properties such as elongation, tear conduction strength and rubbing fatigue resistance will not be sufficiently improved. In addition, there is a tendency for a defect that the film sticks to the roll to easily occur.

The aforementioned elongation ratio is preferably 1.1 to 3 times, more preferably 1.3 to 2.5 times. If the elongation ratio is in such a range, the mechanical properties such as elongation ratio, tear conduction strength and kneading fatigue resistance of the film can be greatly improved. As a result, films can be produced with little thickness nonuniformity, essentially zero birefringence (and thus low retardation), and low haze.

The above-mentioned (meth)acrylic resin film may be subjected to heat treatment (annealing) or the like after stretching in order to stabilize optical isotropy or mechanical properties. Any appropriate conditions can be adopted for the conditions of the heat treatment.

The photoelastic coefficient of the (meth)acrylic resin film is preferably from -3 to -100×10 ^-13 Pa ^-1 , more preferably from -5 to -70×10 ^-13 Pa ^-1 , and still more preferably from -15 to -50×10 ^-13 Pa ^-1 . In addition, the photoelastic coefficient can be measured by the aforementioned method.

The thickness of the (meth)acrylic resin film is preferably from 10 μm to 200 μm, more preferably from 20 μm to 100 μm. When the thickness is less than 10 μm, the strength may be lowered. When the thickness exceeds 200 μm, there is a possibility that the transparency may be lowered.

When laminating the protective film on both sides of the polarizer, the same film as above can be bonded to both sides, or other resin films can be used. For example, an olefin-based resin film, a polyester-based resin film, and a cellulose-based resin film can be preferably used.

Chain polyolefin-based resins include copolymers composed of two or more chain olefins in addition to homopolymers of chain olefins such as polyethylene resin (polyethylene resin that is a homopolymer of ethylene, or a copolymer mainly composed of ethylene), and polypropylene resin (polypropylene resin that is a homopolymer of propylene, or a copolymer mainly composed of propylene).

Cyclic polyolefin-based resins are a general term for resins polymerized with cyclic olefins as polymerization units, and examples thereof include resins described in JP-A-1-240517, JP-A-3-14882, and JP-A-3-122137. Specific examples of cyclic polyolefin-based resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and chain olefins such as ethylene and propylene (typically random copolymers), graft polymers of these modified with unsaturated carboxylic acids or derivatives thereof, and hydrogenated products of these. Among them, a norbornene-based resin utilizing a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer as a cyclic olefin can be preferably used.

The polyester-based resin is a resin having an ester bond other than the following cellulose ester-based resins, and is generally composed of a polycondensate of a polycarboxylic acid or its derivative 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, polydimethyl terephthalate, and dimethyl naphthalene dicarboxylate. As the polyhydric alcohol, divalent diols can be used, and examples thereof include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol. A representative example of the polyester-based resin includes polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

Cellulose ester-based resins are esters of cellulose and fatty acids. Specific examples of cellulose ester-based resins include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. In addition, these copolymers, or those in which a part of hydroxyl groups have been modified with other substituents are also mentioned. Among these, cellulose triethanol ester (cellulose triacetate) is particularly preferred.

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

As mentioned above, the protective film may have a surface treatment layer (coating layer) such as 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). In addition, the thickness of the protective film includes the thickness of the surface treatment layer.

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

Examples of the water-based adhesive include an adhesive composed of a polyvinyl alcohol-based resin aqueous solution, a water-based two-component urethane-based emulsion adhesive, and the like. Among them, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is preferably used. As polyvinyl alcohol-based resins, in addition to vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate that is a homopolymer of vinyl acetate, polyvinyl alcohol-based copolymers obtained by saponifying copolymers of vinyl acetate and other monomers that can be copolymerized with it, or modified polyvinyl alcohol-based polymers obtained by partially modifying the hydroxyl groups of these, etc. can be used. The water-based adhesive may contain cross-linking agents such as aldehyde compounds (glyoxal, etc.), epoxy compounds, melamine-based compounds, methylol compounds, isocyanate compounds, amine compounds, and polyvalent metal salts.

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

The above-mentioned active energy ray-curable adhesive is an adhesive containing a curable compound curable by irradiation of active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, and is preferably an ultraviolet-curable adhesive.

The aforementioned curable compound may be a cation polymerizable curable compound or a radical polymerizable curable compound. Examples of cationically polymerizable hardening compounds include epoxy-based compounds (compounds having one or more epoxy groups in the molecule), oxetane-based compounds (compounds having one or more oxetane rings in the molecule), or combinations thereof. Examples of radically polymerizable hardening compounds include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), other vinyl compounds having radically polymerizable double bonds, or combinations thereof. A cation polymerizable curable compound and a radical polymerizable curable compound may also 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 above-mentioned curable compound.

When bonding a polarizer and a protective film, surface activation treatment may be given to the bonding surface of at least one of them in order to improve adhesiveness. Surface activation treatment can include: dry treatment such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionizing active line treatment (ultraviolet treatment, electron beam treatment, etc.); wet treatment such as ultrasonic treatment using solvents such as water or acetone, saponification treatment, and anchor coating treatment. These surface-activating treatments may be performed alone or in combination of two or more.

When bonding protective films on both sides of the polarizer, the adhesive used to bond the protective films may be the same type of adhesive or a different type of adhesive.

Also, the bonding method through the aforementioned adhesive or adhesive can be used not only for bonding polarizers and protective films, but also for bonding other optical functional layers contained in the optical laminate of the present invention. For example, when the optical layered body has two or more retardation films, it can be used for lamination of the retardation films.

<Adhesive layer>

The adhesive layer 12 may be composed of an adhesive composition mainly composed of (meth)acrylic, rubber, urethane, ester, silicone, and polyvinyl ether resins. Among them, an adhesive composition using a (meth)acrylic resin excellent in transparency, weather resistance, heat resistance, etc. as a matrix polymer is suitable. The adhesive composition may be an active energy ray curing type or a thermosetting type. The thickness of the adhesive layer is usually 3 to 30 μm, preferably 3 to 25 μm.

The (meth)acrylic resin (matrix polymer) used in the adhesive composition is preferably a polymer or a copolymer using one or more (meth)acrylates such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate as monomers. The matrix polymer is preferably copolymerized with polar monomers. Examples of polar monomers include monomers having carboxyl groups, hydroxyl groups, amide groups, amino groups, epoxy groups, etc. such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

The adhesive composition may only contain the above-mentioned matrix polymer, but usually further contains a cross-linking agent. Examples of the crosslinking agent include metal ions having a valence of two or more and forming a metal carboxylate salt with a carboxyl group; polyamine compounds and forming an amide bond with a carboxyl group; polyepoxides or polyols and forming an ester bond with a carboxyl group; polyisocyanate compounds and forming an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferred.

The adhesive layer and the adhesive composition will be described using an example of the adhesive layer 12 used for laminating the optical laminate of the present invention and the organic EL display element, but it is not limited thereto. For example, it can also be used for the lamination of the optical layered body of the present invention and other optical functional layers, or the bonding of the optical functional layers constituting the optical layered body.

<front panel>

The front panel is arranged on the viewing side of the polarizer. The front panel can be laminated on the polarizing plate via an adhesive layer. As an adhesive layer, for example, the above-mentioned adhesive agent layer or adhesive agent layer is mentioned. As shown in FIG. 2 , the front panel 5 can be laminated on the polarizing plate 3 via an adhesive layer (not shown). As shown in FIG. 2 , the front panel 5 may be formed with a light-shielding pattern 6 .

As the front panel, glass and resin films having a hard coat layer on at least one surface thereof are exemplified. As the glass, for example, high transmission glass or tempered glass can be used. Especially when using a thin transparent surface material, chemically strengthened glass is preferred. The thickness of the glass can be set to, for example, 100 μm to 5 mm.

The front panel including the hard coat layer on at least one side of the resin film is not hard like the existing glass, but can have the property of flexibility. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 to 100 μm.

The resin film may be a film formed of the following polymers: cycloolefin-based derivatives having units of cycloolefin-containing monomers such as norcamphene or polycyclic norbornene-based monomers, cellulose (cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, isobutyl cellulose, cellulose propionate, cellulose butyrate, cellulose acetate propionate) ethylene-vinyl acetate copolymer, polycycloolefin, polyester, polystyrene, polyamide, polyether imide, polyacrylic acid, poly Imide, polyamide imide, polyether sulfide, polyethylene, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl ketone, polyether ketone, polyether ether ketone, polyether ketone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate, polycarbonate, polyurethane, epoxy, etc. As the resin film, unstretched, uniaxially or biaxially stretched films can be used. These polymers can be used individually or in mixture of 2 or more types, respectively. The resin film is preferably a polyamide-imide film or a polyimide film excellent in transparency and heat resistance, a uniaxially or biaxially stretched polyester film, a cycloolefin-based derivative film having excellent transparency and heat resistance and capable of scaling up the film, a polymethyl methacrylate film, and cellulose triacetate and isobutyl cellulose film having transparency and no optical anisotropy. The thickness of the resin film may be 5 to 200 μm, preferably 20 to 100 μm.

The aforementioned hard coat layer can be formed by hardening a hard coat composition containing a reactive material that forms a crosslinked structure due to irradiation of light or heat energy. The hard coat layer can be formed by curing a hard coat composition containing both a photocurable (meth)acrylate monomer or oligomer and a photocurable epoxy monomer or oligomer. The photocurable (meth)acrylate monomer may contain 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 coating composition may further contain at least one selected from the group consisting of solvents, photoinitiators and additives. The additives may contain more than one selected from the group consisting of inorganic nanoparticles, leveling agents, and stabilizers. In addition, each component commonly used in this technical field may further contain, for example, antioxidants, UV absorbers, surfactants, lubricants, and antifouling agents.

<shading pattern>

The light-shielding pattern may be provided as at least a part of a front panel or a frame or a case of a display device to which the front panel is applied. The light-shielding pattern may be formed on the display element side in the front panel. The light-shielding pattern can hide each wiring of the display device so as not to be watched by the user. The color and/or material of the light-shielding patterns are not particularly limited, and may be formed of resin materials with various colors such as black, white, and gold.

In one embodiment, the thickness of the light-shielding pattern may range from 2 μm to 50 μm, preferably from 4 μm to 30 μm, and more preferably from 6 μm to 15 μm. Moreover, in order to suppress the mixing of air bubbles and viewing of a boundary part by the level difference between a light-shielding pattern and a display part, you may give a shape to a light-shielding pattern.

<Touch sensor>

A touch sensor is used as an input means. As for the touch sensor, various types such as a resistive film type, a surface elastic wave type, an infrared type, an electromagnetic induction type, and a capacitive type have been proposed, and any type may be used. Among them, the capacitive type is preferable. A capacitive touch sensor is divided into an active area and an inactive area located on the periphery of the active area. The active area is the area corresponding to the area (display portion) that displays images on the display panel and can sense user touches, while the inactive area is the area corresponding to the area (non-display portion) that displays images on the image display device. The touch sensor may include: a substrate; a sensing pattern formed on the active area of the substrate; and sensing lines formed on the inactive area of the substrate and connected to an external driving circuit through the sensing pattern and the pad portion. As the substrate, glass or the same material as the resin film constituting the above-mentioned front panel can be used. From the viewpoint of crack suppression of the touch sensor, the substrate of the touch sensor should preferably have a hardness of 2,000 MPa% or more. The better system performance can be more than 2,000MPa% and less than 30,000MPa%.

The sensing pattern may include a first pattern formed in the first direction and a second pattern formed in the second direction. The first pattern and the second pattern are arranged in different directions from each other. The first pattern and the second pattern are formed on the same layer, and in order to sense the touched position, each pattern must be electrically connected. Although the first pattern is a form in which each unit pattern is connected to each other through a junction, the second pattern is a structure in which each unit pattern is separated into an island shape, so in order to electrically connect the second pattern, an additional bridge electrode (bridge electrode) is required. Known transparent electrode materials can be used for the sensing pattern. Examples include indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), PEDOT (poly(3,4-ethylenedioxythiophene)), carbon nanotubes (CNT), graphene, metal wires, etc., and these can be used alone or in combination of two or more. Preferably, ITO can be used. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, tellurium, and chromium. These can be used individually or in mixture of 2 or more types.

The bridge electrode can be formed on the top of the insulating layer via the insulating layer on the top of the sensing pattern, the bridge electrode is formed on the substrate, and the insulating layer and the sensing pattern can be formed thereon. The bridging electrodes can also be formed of the same material as the sensing pattern, such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium or alloys of two or more of them. Since the first pattern and the second pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridging electrodes. The insulating layer may be formed only between the junction of the first pattern and the bridge electrodes, or may be formed in a layer structure covering the sensing pattern. In the latter case, the bridge electrode can be connected to the second pattern through the connection hole formed in the insulating layer.

As a means for properly compensating for the difference in transmittance between the patterned area and the non-patterned area, specifically, as a means for appropriately compensating for the difference in light transmittance induced by the difference in refractive index in these areas, the touch sensor may further include an optical adjustment layer between the substrate and the electrode, and the optical adjustment layer may contain inorganic insulating substances or organic insulating substances. 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 may further contain inorganic particles. The refractive index of the optical adjustment layer can be increased by the inorganic particles.

The photocurable organic adhesive may contain, for example, copolymers of monomers such as acrylate-based monomers, styrene-based monomers, and carboxylic acid-based monomers. The photocurable organic adhesive may be, for example, a copolymer including various repeating units different from each other, such as epoxy group-containing repeating units, acrylate repeating units, and carboxylic acid repeating units. The inorganic particles may contain, for example, zirconia particles, titania particles, alumina particles, and the like. The photocurable composition may further contain various additives such as photopolymerization initiators, polymerizable monomers, and curing aids.

<Manufacturing method of optical layered body>

A method for producing an optical layered body will be described taking the optical layered body shown in (a) to (c) of Fig. 1 as an example.

The optical layered body 100 (FIG. 1(a)) can be manufactured as follows, for example. An alignment layer 11 is formed on the substrate, and a coating solution containing a polymerizable liquid crystal compound is coated on the alignment layer 11 . In the state where the polymerizable liquid crystal compound is aligned, heat treatment or active energy ray irradiation is performed to harden the polymerizable liquid crystal compound. After the polymerizable liquid crystal compound is cured to form the phase difference layer 10, the substrate is peeled off, and the adhesive layer 12 and the alignment layer 11 formed on the release film are separated from the substrate.

In the case of the optical laminate 101 shown in FIG. 1 (b), the step of forming the retardation layer 10 is the same as the optical laminate 100 shown in FIG. 1 (a). After the retardation layer 10 is formed, the retardation layer 10 and the second retardation film are laminated through the adhesive layer 13. When the optical layered body 100 and the retardation layer 10 are elongated, the respective members can be bonded from roll to roll via the adhesive layer 13 . After laminating the optical layered body 100 and the second retardation film, the substrate is peeled off, and the adhesive layer 12 and the alignment layer 11 formed on the peeling film are separated from the substrate.

In the case of the optical layered body 102 shown in FIG. 1(c), first, the polarizing plate 3 is manufactured. The polarizer 3 can be manufactured by laminating a polarizer and a protective film through an adhesive.

The protective film has only to be laminated on at least one side of the polarizer. The polarizing plate can be manufactured by preparing elongated members, bonding each member in a roll-to-roll manner, and then cutting into a predetermined shape, or cutting each member into a predetermined shape and bonding them together. After attaching the protective film to the polarizer, a heating step or a humidity adjustment step can be set. The retardation film is the same as the optical laminate 101 in FIG. 1 (b), and the step of laminating the second retardation film is the same, and the second retardation film is laminated with the polarizing plate 3 via the adhesive layer or adhesive layer on the surface opposite to the adhesive layer 13. When the polarizing plate 3 or the optical layered body 101 is elongated, each member can be bonded together in a roll-to-roll manner. After laminating the polarizing plate 3, the substrate is peeled off, and the adhesive layer 12 and the alignment layer 11 formed on the release film are separated from the substrate.

Then, the organic EL display device can be fabricated by peeling off the release film laminated on the adhesive layer 12 and bonding the optical laminate and the organic EL display element through the adhesive layer 12 .

<purpose>

The optical layered body of the present invention can be used in various display devices. The so-called display device refers to a device having a display element and including a light emitting element or light emitting device as a light emitting source. Examples of display devices include liquid crystal display devices, organic EL display devices, inorganic electroluminescence (hereinafter referred to as inorganic EL) display devices, electron emission display devices (such as field emission display devices (called FED), surface field emission display devices (called SED)), electronic paper (display devices using electronic ink or electrophoretic elements), plasma display devices, projection display devices (such as grid light valve (called GLV) display devices, display devices with digital micromirror devices (called DMD) ), and piezoelectric ceramic displays. The liquid crystal display device includes any one of a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, and the like. These display devices may be display devices that display 2D images, or may be stereoscopic display devices that display 3D images. In particular, the optical layered body can be used particularly effectively for an organic EL display device or an inorganic EL display device.

In FIG. 2 , an organic EL display device 103 has a layer configuration 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 .

In addition, the display device may also be a flexible display device or a flexible organic EL display device. A flexible organic EL display device includes the optical laminate of the present invention and an organic EL display element. Compared with the organic EL display element, the optical laminated system of the present invention is arranged on the viewing side to form a bendable one. The term "bendable" refers to one that can be bent without cracks or breakage. 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 panel and a touch sensor.

Specific examples of optical laminates include ones in which the front panel, polarizer, retardation film, and touch sensor are laminated sequentially from the viewing side, or ones in which the front panel, touch sensor, polarizer, and retardation film are laminated sequentially from the viewing side. When there is a polarizing plate on the viewing side of the touch sensor, it is difficult to view the pattern of the touch sensor, so that the visibility of the displayed image is improved, which is preferable. Each member can be laminated using an adhesive, an adhesive, or the like. In addition, a light-shielding pattern formed on at least one surface of any one of the front panel, polarizing plate, retardation film, and touch sensor may be provided.

(Example)

Examples are given below to describe the present invention more specifically, but the present invention is not limited by these examples. In the examples, parts and % indicating the content or usage amount are based on weight unless otherwise noted. In addition, the measurement of each physical property in the following example was performed by the following method.

(1) Determination of film thickness

The measurement was performed using a digital micrometer MH-15M manufactured by Nikon Corporation.

(Determination of puncture elastic modulus)

The 1st retardation film with a base film obtained in the Example and the comparative example was cut out into the slice of 40 mm long x 40 mm wide. Also, prepare a bottom paper with glue of 40 mm in length and 40 mm in width. A square of 30 mm x 30 mm was cut out in the center of this glued backing paper. After the laminate was bonded to the adhesive base paper so that the surface of the retardation layer 1 was in contact with the paste of the adhesive base paper, the base material was peeled off from the first retardation film to prepare a sample for the thrust test.

、0.5R者。針的穿刺速度設為0.33cm/秒。相位差膜1的穿刺彈性模數呈示於表1。測定係在溫度23℃、濕度50%的室溫環境下進行。 The measurement of the puncture elastic modulus is carried out in the following manner. The needle was attached to "NDG5 puncture tester" manufactured by Kato-tech Co., Ltd., and it carried out. The needle was stabbed vertically on the main surface of the sample for the thrust test (the surface of the retardation layer 1), and the stress F (g) before the sample for the thrust test was broken and the deformation S (mm) at this time were calculated, and the puncture elastic modulus (g/mm) was calculated as stress F (g)/deformation S (mm). The diameter of the front end of the needle system is 1mm

, 0.5R person. The piercing speed of the needle was set at 0.33 cm/sec. The puncture modulus of the phase difference film 1 is shown in Table 1. The measurement system is carried out in a room temperature environment with a temperature of 23°C and a humidity of 50%.

(3) Evaluation of abrasion resistance (hardness of steel wool)

The abrasion resistance of the alignment layer surface of the phase difference film was evaluated by a steel wool test.

Using a steel wool tester (manufactured by Daiei Seiki Co., Ltd.), a cleaning cloth for a clean room (BEMCOT AZ-8 manufactured by Asahi Kasei Co., Ltd.) was placed in contact with the surface of an alignment layer formed by film-forming in the same manner as in Examples and Comparative Examples on a cyclic polyolefin-based resin (COP) substrate (thickness 20 μm) placed on a glass plate under a load of 500 g, and the abrasion test was performed four times at a speed of 40 r/min. Count the number of scratches produced.

(4) Evaluation of abrasion resistance (evaluation of pencil hardness)

The evaluation of the surface hardness of the alignment layer surface of the retardation film was performed by a pencil hardness test.

With a pencil hardness tester (No.553-M1 manufactured by Yasuda Seiki Co., Ltd.), a pencil for testing (unistar manufactured by Mitsubishi Pencil Co., Ltd.) was contacted with a load of 500 g on a cyclic polyolefin-based resin (COP) substrate (thickness 20 μm) arranged on a glass plate with the surface of the alignment layer formed by the film in the same manner as in each embodiment and comparative example from an angle of 45 degrees, and a hardness test was carried out at a speed of 0.5 mm/sec. Under the fluorescent light, the presence or absence of scratches was visually counted. In 5 tests, confirm the hardness of less than 1 scratch.

[Example 1]

(Preparation of the first retardation film 1)

The composition for forming the alignment layer was prepared by dissolving the following in 70.0 parts by weight of a solvent methyl ethyl ketone to prepare a coating solution for forming an alignment layer: 10.0 parts by weight of polyethylene glycol di(meth)acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd. A-600), 10.0 parts by weight of trimethylolpropane triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd. Stock) A-HD-N) 10.0 parts by weight, and 1.50 parts by weight of Irgacure 907 (Irg-907 manufactured by BASF Corporation) as a photopolymerization initiator.

A long cyclic olefin-based resin film with a thickness of 20 μm (manufactured by Zeon Co., Ltd. Japan) was prepared as a base film, and the obtained coating solution for forming an alignment layer was coated on one side of the base film with a bar coater.

After the coating layer was heat-treated at 80° C. for 60 seconds, it was irradiated with 220 mJ/cm ² of ultraviolet rays (UVB) to polymerize and harden the composition for forming the alignment layer to form an alignment layer 1 with a thickness of 3.5 μm on the substrate film.

A coating solution for forming a retardation layer was prepared by dissolving 20.0 parts by weight of a photopolymerizable nematic liquid crystal compound (RMM28B manufactured by Merck) as a composition for forming a retardation layer and 1.0 parts by weight of Irgacure 907 (Irg-907 manufactured by BASF) as a photopolymerization initiator in a solvent of 80.0 parts by weight of propylene glycol monomethyl ether acetate.

The coating solution for forming a retardation layer was coated on the obtained alignment layer, and the coating layer was subjected to heat treatment at a temperature of 80° C. for 60 seconds. Then, 220 mJ/cm ² of ultraviolet rays (UVB) was irradiated to polymerize and harden the composition for forming the retardation layer, and to form the retardation layer 1 with a thickness of 0.7 μm on the alignment layer. In this way, the first retardation film 1 composed of the alignment layer 1 and the retardation layer 1 was obtained on the base film. The first retardation film 1 exhibits a retardation in the thickness direction. Moreover, it was confirmed that the 1st retardation film 1 can be peeled from a base film.

(Production of polarizing plate)

A polyvinyl alcohol film with a thickness of 20 μm (average degree of polymerization about 2400, saponification degree above 99.9 mol%) was uniaxially stretched to about 4 times by dry stretching, and then maintained in a stretched state, immersed in pure water at 40°C for 40 seconds, and then 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 to perform dyeing. Then, it was immersed in the aqueous solution whose weight ratio of potassium iodide/boric acid/water was 11.0/6.2/100 at 70 degreeC for 120 second. Next, after washing with pure water at 8°C for 15 seconds, drying was carried out at 60°C for 50 seconds and then at 75°C for 20 seconds while maintaining a tension of 300 N to obtain an absorption-type polarizer film with a thickness of 8 μm in which iodine was adsorbed and aligned on the polyvinyl alcohol film. A water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution was coated on both sides of the obtained polarizer film, and a protective film (COP film Zeonor ZF14 manufactured by Zeon) was attached to one side of the polarizer film, and a protective film (TAC film Fujitac TJ25 manufactured by Fujifilm) was attached to the other side of the polarizer film to obtain a polarizing plate with protective films on both sides.

(Production of optical laminates)

After peeling off the release film on one side of a sheet-shaped adhesive with a release film on both sides (thickness: 25 μm P-3132 manufactured by Lintec Co., Ltd.), and bonding it to the TAC film side surface of the obtained polarizing plate through the adhesive layer, the release film on the other side of the sheet-shaped adhesive was peeled off, and the adhesive was laminated on the TAC film side surface of the polarizing plate. After bonding the retardation layer 1 side surface of the first retardation film to the polarizing plate through the laminated adhesive layer, the base film was peeled from the first retardation film 1 . Then, after peeling off the release film on one side of the above-mentioned sheet-like adhesive with release film on both sides, the adhesive layer is attached to the surface of the first retardation film 1 peeled off from the base film to obtain an optical laminate with a laminated structure of polarizing plate/adhesive layer/first retardation film 1/adhesive layer/release film.

[Example 2, 3, Comparative Example 1, 2]

The optical laminates of Examples 2, 3, and Comparative Examples 1 and 2 were produced in the same manner as in Example 1, except that the composition for forming the alignment layer 1 and the retardation layer 1 constituting the first retardation film was changed to the compounding ratio and thickness shown in Table 1. In addition, the first retardation film obtained in Examples 2 and 3 and Comparative Examples 1 and 2 exhibited a retardation in the thickness direction.

[Example 4]

The composition for forming an alignment layer was set to the materials and blending ratios in Table 1 to prepare a coating liquid for forming an alignment layer, and the coating layer of the coating liquid was heat-treated at a temperature of 100° C. for 120 seconds to harden.

Except for this, the optical layered body was produced by the method similar to Example 1. In addition, the first retardation film obtained in Example 4 exhibited a retardation in the thickness direction.

[Example 5]

[Production of the first retardation film 2]

A composition for forming an alignment film was obtained by mixing 5.0 parts by weight of a photo-alignment material having the following structure (weight average molecular weight: 30,000) and 95.0 parts by weight of cyclopentanone (solvent), and stirring the resulting mixture at 80° C. for 1 hour.

The following polymerizable liquid crystal compound A and polymerizable liquid crystal compound B were mixed at a mass ratio of 9:1, and 0.1 part by weight of a leveling agent (F-556; manufactured by DIC Corporation) and 0.6 part by weight of 2-dimethylamino-2-benzyl-1-(4-morpholinylphenyl)butan-1-one ("Irgacure369 (Irg369)", manufactured by BASF Japan Co., Ltd.) were added to 10 parts by weight of the obtained mixture. portion.

Moreover, N-methyl-2-pyrrolidone (NMP) was added so that solid content concentration might become 13 %, and it stirred at 80 degreeC for 1 hour, and obtained the composition for liquid crystal cured film formation.

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

(Polymerizable Liquid Crystal Compound A)

(Polymerizable Liquid Crystal Compound B)

[Manufacture of a laminate including a substrate, an alignment film, and a layer cured from a polymerizable liquid crystal compound]

Corona treatment was performed on a 50-μm-thick cycloolefin-based film [trade name "ZF-14-50" manufactured by Zeon Co., Ltd.] as a base material. The composition for forming an alignment film was applied to the corona-treated surface with 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" of Ushio Electric Co., Ltd.] to obtain an alignment film. Irradiation of polarized light UV was performed so that the cumulative light quantity at a wavelength of 313 nm would be 100 mJ/cm ² .

Then, the composition for forming a liquid crystal cured film was applied on the alignment film using a bar coater. The coated 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 Electric Co., Ltd.: "Yunikyua VB-15201BY-A"]. The step of irradiating ultraviolet rays was performed under a nitrogen atmosphere so that the cumulative light intensity at a wavelength of 365 nm was 250 mJ/cm ² . After the irradiation, put the cured film into an oven set at 5° C. for 20 seconds as a cooling step. Immediately after taking it out from the oven, the aforementioned ultraviolet irradiation step and cooling step were carried out again, and the first retardation film 2 including an alignment film and a layer hardened by a polymerizable liquid crystal compound was obtained on the substrate. The first retardation film 2 exhibits a retardation in the in-plane direction. An optical layered body 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]

The first retardation film was produced in the same manner as in Comparative Example 1, except that the alignment layer 1 and the retardation layer 1 were peeled off when the optical laminate was produced, and the first retardation film was only used as the retardation layer 1, and the optical laminate of Example 6 was produced in the same manner as in Example 1.

For the optical laminates obtained in Examples 1 to 6 and Comparative Examples 1 and 2, the peeling film was peeled off, and the exposed adhesive layers were respectively attached to glass plates to form the state shown in Fig. 3, and then the heat shock resistance test was carried out by the method shown below.

The tip of an Erichsen Pen (Model 318 manufactured by Erichsen Co., Ltd.) set to a load of 10 N was pushed against the surface of the polarizing plate in the optical layered body opposite to the glass plate as a starting point. Set other 2 similar starting points at equal intervals (total 3 locations). Thereafter, a heat shock test (ESPEC CORP. product name: TSA-303EL-W) was implemented for several cycles, with 30 minutes at -20° C. and 30 minutes at 60° C. as one cycle. Before the thermal shock test, measure the length of cracks generated from each starting point of the Ericsson pen originally pushed against the surface of the polarizer in the optical laminate, and take the average of the crack measurement results at 3 starting points as the crack length (mm).

Table 2 shows the puncture elastic modulus, film thickness, abrasion resistance evaluation (steel wool, pencil hardness) and thermal shock test results of the optical laminate of the first retardation film obtained in Examples 1 to 6 and Comparative Examples 1 and 2. The puncture elastic modulus of the first retardation film of Examples 1 to 5, Comparative Examples 1 and 2 was measured by detaching the substrate film from the laminate of the first retardation film and the base film, and pressing the puncture aid from the retardation layer 1 side to the first retardation film (retardation layer 1+alignment layer 1). The first retardation film in Example 6 is obtained by peeling the substrate film and the alignment layer 1 from the retardation layer 1, and the results of measurements on the first retardation film (only the retardation layer 1) are shown. In addition, the abrasion resistance evaluation was carried out on the alignment layers of Examples 1 and 2, and Comparative Example 1.

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, the molecular weight Mi and the number of functional groups Ni of the polymerizable compound i. The polymeric base amount of the alignment layer is the value N1 calculated by formula (A-1).

In addition, Table 3 shows the thickness L _LC of the retardation layer in the retardation film obtained in each example and each comparative example, the content Cwj of units derived from the polymerizable liquid crystal compound j constituting the retardation layer, the molecular weight Mj and the number of functional groups Nj of the polymerizable liquid crystal compound j. The polymeric base amount of the retardation layer is the value N2 calculated by the formula (A-2).

Moreover, the polymeric group amount N calculated by the said calculation formula (A) is shown together in Table 3.

(industrial availability)

According to the present invention, it is useful to provide an optical layered body that includes a retardation film and suppresses generation of cracks even in an environment subjected to severe temperature changes.

1‧‧‧The first retardation film (retardation film)

2‧‧‧The second retardation film

3‧‧‧Polarizer

10‧‧‧retardation layer

11‧‧‧Alignment layer

12‧‧‧adhesive layer

13‧‧‧adhesive layer

100, 101, 102‧‧‧optical laminate

Claims (6)

An optical laminate having a retardation film, and when the retardation film is broken by pressing the front end of the puncture aid perpendicular to the film surface, the puncture elastic modulus calculated by the following formula (1) using the stress F (g) applied to the retardation film from the front end of the puncture aid and the deformation S (mm) of the retardation film is 50 g/mm or less, (1) The puncture elastic modulus (g/mm)=F(g)/S(mm) The amount S is the amount of deformation caused by bending the film toward the puncture direction. The measurement of the puncture elastic modulus is carried out under the following conditions: use the test sample obtained by attaching the film to the base paper with adhesive and cut out a square of 30mm×30mm in the center, and press the front end diameter at a speed of 0.33cm/sec to 1mm

. The front end of the puncture aid of 0.5R; the aforementioned retardation film contains a retardation layer and an alignment layer hardened by a polymerizable liquid crystal compound, and the polymeric base amount N of the retardation film calculated according to the following calculation formula (A) is 0.67 or less,

計算式(A)中，AL表示來自構成樹脂之聚合性化合物的構成單元的種類數，其中該樹脂構成配向層，該配向層構成相位差膜，Cwi表示以來自構成配向層的樹脂中之聚合性化合物的全構成單元為基準，來自聚合性化合物i的構成單元之含量(質量%)，Mi表示構成配向層的聚合性化合物i之分子量，Ni表示構成配向層的聚合性化合物i所具有的聚合性基之數量，LC表示來自構成相位差層的聚合性液晶化合物之構成單元的種類數，Cwj表示以來自相位差層中之聚合性液晶化合物之全構成單元為基準，來自聚合性液晶化合物j之構成單元的含量(質量%)，Mj表示構成相位差層的聚合性液晶化合物j之分子量， Nj表示構成相位差層的聚合性液晶化合物j所具有的聚合性基之數量，L _AL表示配向層的厚度(μm)，L _LC表示相位差層的厚度(μm)，L _total表示L _AL與L _LC之和。 The optical laminated body as described in claim 1, wherein the retardation layer has vertical alignment. The optical layered body according to claim 1, wherein the optical layered body further has a polarizing plate. The optical laminated body described in claim 3, wherein the said optical laminated body further has a front plate, and said front plate is arrange|positioned at the viewing side of said polarizing plate. The optical laminated body as described in Claim 4, wherein the aforementioned optical laminated body further has a touch sensor. A display device is a display device in which the optical laminate volume described in any one of items 1 to 5 of the patent application is layered on the display element.