TW202409621A - Optical laminated body and method for manufacturing same - Google Patents

Abstract

Provided is an optical laminated body having excellent bendability. The optical laminated body includes a transparent protective film, a first adhesive layer, a polarizer, a second adhesive layer, an optical anisotropic layer, and an adhesive layer in this order. Only the first adhesive layer is present between the transparent protective film and the polarizer, and only the second adhesive layer is present between the polarizer and the optical anisotropic layer. The optical anisotropic layer is a liquid crystal cured film, and the thickness of the optical anisotropic layer is 0.1-5 [mu]m. The optical anisotropic layer and the adhesive layer are directly in contact with each other or there is an alignment layer between the optical anisotropic layer and the adhesive layer.

Description

Optical laminated body and manufacturing method thereof

The present invention relates to an optical laminate and a manufacturing method thereof.

An elliptical polarizing plate is an optical member formed by laminating a polarizing plate and a phase difference plate. For example, in image display devices such as organic EL (Electroluminescence) image display devices, the elliptical polarizing plate is used to prevent the device from forming The light is reflected at the electrode. As a retardation plate, a retardation plate using a liquid crystal cured film produced by applying a polymerizable liquid crystal compound to a base material and curing it is known (Patent Document 1). [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 2022-044293

[The problem the invention is trying to solve]

In recent years, with the popularity of bendable flexible displays, elliptical polarizers are also required to have further flexibility. The purpose of the present invention is to provide an optical multilayer with excellent flexibility. [Technical means to solve the problem]

The present invention provides the following optical laminated body and its manufacturing method. [1] An optical laminate including a transparent protective film, a first adhesive layer, a polarizing element, a second adhesive layer, an optically anisotropic layer, and an adhesive layer in this order, Only the first adhesive layer is interposed between the transparent protective film and the polarizing element, and only the second adhesive layer is interposed between the polarizing element and the optical anisotropic layer. The above-mentioned optically anisotropic layer-based liquid crystal cured film, The thickness of the above-mentioned optically anisotropic layer is 0.1 μm or more and 5 μm or less, and The optically anisotropic layer is directly connected to the adhesive layer, or an alignment layer is included between the optically anisotropic layer and the adhesive layer. [2] The optical laminated body according to [1], wherein the thickness of the first adhesive layer and the second adhesive layer is 50 nm or more and 2000 nm or less. [3] The optical laminate according to [1] or [2], wherein the first adhesive layer and the second adhesive layer are layers formed of a dry curable adhesive or an active energy ray curable adhesive. . [4] The optical laminate according to any one of [1] to [3], wherein the optically anisotropic layer has reverse wavelength dispersion. [5] The optical laminate according to any one of [1] to [4], wherein the in-plane phase difference value of the optically anisotropic layer with respect to light with a wavelength of 550 nm is 100 nm or more and 160 nm or less. [6] The optical laminate according to any one of [1] to [5], wherein the optically anisotropic layer has an optical axis that is oblique to the longitudinal direction of the polarizing element. [7] The optical laminate according to any one of [1] to [6], wherein the alignment layer is a photo-alignment film containing a photo-alignment polymer containing a photoreactive group. [8] The optical laminate according to any one of [1] to [7], further comprising an anti-reflection layer on the side of the transparent protective film opposite to the polarizing element. [9] The optical laminate according to any one of [1] to [8], wherein the polarizing element contains a polyvinyl alcohol-based resin film containing a dichroic dye. [10] An image display device including the optical layered body according to any one of [1] to [9]. [11] A method for manufacturing an optical laminated body, which is the method for manufacturing an optical laminated body as described in any one of [1] to [9], and includes: The retardation film preparation step is to prepare a retardation film including an optical anisotropic layer, an alignment layer, and a base film in sequence; The first laminating step is to laminate the above-mentioned transparent protective film and the above-mentioned polarizing element using a first adhesive; The second laminating step involves laminating the polarizing element and the optical anisotropic layer of the retardation film using a second adhesive; a peeling step of peeling and removing the base film, or the base film and the alignment layer from the laminate obtained in the second laminating step; and The adhesive layering step is to layer the adhesive layer on the area exposed by the peeling step. [12] The method for manufacturing an optical laminated body according to [11], wherein the first adhesive and the second adhesive are active energy ray-curable adhesives. [13] The method for manufacturing an optical laminated body according to [12], which further includes, after the second bonding step and before the peeling step, the following step: from the laminate obtained by the second bonding step The retardation film side of the body is irradiated with active energy rays to harden the first adhesive and the second adhesive. [Effects of the invention]

The present invention can provide an optical multilayer with excellent flexibility.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. All the following drawings are shown to help understand the present invention. The size or shape of each component shown in the drawings is not necessarily consistent with the size or shape of the actual component.

＜Optical laminated body＞ (1) Composition of optical laminate 1 and 2 are schematic cross-sectional views showing an example of the layer structure of the optical laminated body (hereinafter, also simply referred to as "optical laminated body") of the present invention. The optical laminated body 1 shown in FIG. 1 includes a transparent protective film 10, a first adhesive layer 51, a polarizing element 20, a second adhesive layer 52, an optical anisotropic layer (retardation layer) 30, and an adhesive in this order. Layer 40. The transparent protective film 10 and the polarizing element 20 are laminated via the first adhesive layer 51 . The polarizing element 20 and the optically anisotropic layer 30 are laminated via the second adhesive layer 52 . Only the first adhesive layer 51 is interposed between the transparent protective film 10 and the polarizing element 20 . Only the second adhesive layer 52 is interposed between the polarizing element 20 and the optically anisotropic layer 30 . The optical laminate 1 includes the alignment layer 60 between the optical anisotropic layer 30 and the adhesive layer 40 . In the optical laminate 1, the first adhesive layer 51 is directly in contact with the transparent protective film 10 and the polarizing element 20, the second adhesive layer 52 is in direct contact with the polarizing element 20 and the optical anisotropic layer 30, and the alignment layer 60 Directly connected to the optical anisotropic layer 30 and the adhesive layer 40 .

The optical laminated body 2 shown in FIG. 2 has the same layer structure as the optical laminated body 1 shown in FIG. 1 except that it does not have the alignment layer 60 . In the optical laminate 2, the optically anisotropic layer 30 and the adhesive layer 40 are in direct contact.

As shown in the examples shown in FIGS. 1 and 2 , the optical laminate does not have a base film ( Usually a thermoplastic resin film), the transparent protective film 10 and the polarizing element 20 are bonded using an adhesive layer (first adhesive layer 51), and the polarizing element 20 and the polarizing element 20 are bonded using an adhesive layer (second adhesive layer 52). The optically anisotropic layer 30 is bonded. Since the optical laminate of the present invention has this structure, it has excellent flexibility and is less likely to cause problems such as peeling or cracking in the flexed portion even if it is repeatedly flexed. From the viewpoint of further improving flexibility, when the optical laminate has the alignment layer 60 , it is preferable that only the alignment layer 60 is interposed between the optical anisotropic layer 30 and the adhesive layer 40 .

The optical laminate may include other layers (e.g., other layers having various functions that can be assembled into an image display device, etc.) in addition to the transparent protective film 10, the first adhesive layer 51, the polarizing element 20, the second adhesive layer 52, the optical anisotropic layer 30, the alignment layer 60, and the adhesive layer 40. However, from the perspective of improving the flexibility of the optical laminate, the other layers are not disposed between the transparent protective film 10 and the polarizing element 20, and between the polarizing element 20 and the optical anisotropic layer 30, and preferably, are not disposed between the optical anisotropic layer 30 and the adhesive layer 40.

The optical laminated body is suitably used as an elliptically polarizing plate, for example. The term "elliptically polarizing plate" includes circular polarizing plates.

Hereinafter, the elements constituting or capable of constituting the optical laminate will be described in detail. (2)Transparent protective film The optical laminate includes the transparent protective film 10 laminated on the side opposite to the optical anisotropic layer 30 of the polarizing element 20 . Since the film thickness of the polarizing element 20 is thin, its surface is easily damaged. Therefore, in order to prevent damage or contamination from the outside, protective films are often provided on both sides of the polarizing element 20. However, in the optical laminate of the present invention, A transparent protective film is not laminated on the surface of the polarizing element 20 on the optical anisotropic layer 30 side. This makes it possible to obtain an optical laminate that is thinner and has low oblique reflectivity.

The transparent protective film 10 preferably has a total light transmittance of more than 90%, more preferably more than 92%. If the total light transmittance is equal to or higher than the above-mentioned lower limit, an optical laminate having high transparency and excellent optical properties can be constructed. The upper limit of the total light transmittance of the transparent protective film 10 is not particularly limited, but may be 100% or less. The total light transmittance can be measured in accordance with JIS K 7361, for example.

The transmittance of the transparent protective film 10 at a wavelength of 380 nm is preferably 30% or less, more preferably 25% or less, and further preferably 20% or less. If the transmittance is below the above upper limit, when the optical laminate including the transparent protective film 10 is assembled into an image display device, the internal layers (polarizing element 20 or optical anisotropic layer 30, etc.) constituting the optical laminate can be protected from the ultraviolet rays exposed on the viewing side. The lower limit of the transmittance of the transparent protective film 10 at a wavelength of 380 nm is not particularly limited and can be 0%. In order to set the transmittance of the transparent protective film 10 at a wavelength of 380 nm to less than 30%, the transparent protective film 10 may also include an ultraviolet absorber, etc. The transmittance at a wavelength of 380 nm can be measured, for example, using a spectrophotometer.

As the transparent protective film 10, a thermoplastic resin film can be used. Examples of the thermoplastic resin that can constitute the transparent protective film include: cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether resins; polyester resins; polycarbonate resins; polyamide resins such as nylon or aromatic polyamide; polyimide resins; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymer; cyclic polyolefin resins having a ring system and a norbutylene structure (also called norbutylene resins); (meth) acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins, and mixtures thereof. In addition, in this specification, "(meth)acrylic acid" means either acrylic acid or methacrylic acid. "(Meth)" such as (meth)acrylate and (meth)acryl also have the same meaning. Such resin can be formed into a film by a known method such as solvent casting and melt extrusion. The surface of the transparent protective film can also be subjected to a surface treatment such as a release treatment of a silicone treatment, a corona treatment, a plasma treatment, etc.

The transparent protective film 10 is preferably a triacetyl cellulose film, a (meth)acrylic resin film, a cyclic polyolefin resin film, or a polyethylene terephthalate film.

In one embodiment, the transparent protective film 10 has a moisture permeability of preferably 100 g/m ² /24 hours or more, more preferably 150 g/m ² /24 hours or more, and further preferably 200 g/m ² /24 hours or more. If the moisture permeability of the transparent protective film 10 is above the lower limit, when the optical anisotropic layer 30 and the polarizing element 20 are laminated using the dry curing adhesive to form an optical laminate, the solvent in the dry curing adhesive can be efficiently removed from the transparent protective film 10. This can shorten the time for removing the solvent in the dry curing adhesive, which may also be advantageous in terms of productivity. The upper limit of the moisture permeability of the transparent protective film 10 is not particularly limited, but is usually 1000 g/m ² /24 hours or less, preferably 500 g/m ² /24 hours or less. The moisture permeability is the moisture permeability at a temperature of 40°C and a relative humidity of 90%, and can be measured by the cup method specified in JIS Z 0208.

From the viewpoint of thinning, workability, flexibility and strength of the optical laminate, the thickness of the transparent protective film 10 is usually 5 μm or more and 300 μm or less, preferably 20 μm or more and 200 μm or less, more preferably 20 μm or more. Above μm and below 150 μm.

The transparent protective film 10 may include a surface treatment layer laminated on the surface opposite to the polarizing element 20. Examples of the surface treatment layer include a hard coating layer and an anti-reflection layer. The hard coating layer is used to prevent surface damage, and examples thereof include a hardened film formed by ultraviolet curing resins such as (meth) acrylic acid and polysilicone. The anti-reflection layer is used to prevent the reflection of external light on the surface, and may be a previously known anti-reflection film.

(3) Polarizing element The polarizing element is a film having the function of extracting linear polarization from incident natural light, and is preferably a polyvinyl alcohol resin film containing a dichroic pigment. As the polyvinyl alcohol resin constituting the polyvinyl alcohol resin film, a saponified product of a polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include: polyvinyl acetate which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith (e.g., ethylene-vinyl acetate copolymers, etc.). Examples of other monomers copolymerizable with vinyl acetate include: unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, (meth)acrylamides having an ammonium group, etc.

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

The polyvinyl alcohol resin is formed into a film and used as a blank film of a polarizing element. The method of forming the polyvinyl alcohol resin into a film is not particularly limited, and the film can be formed by a known method. The thickness of the polyvinyl alcohol blank film can be set to, for example, 10 μm or more and 150 μm or less.

Polarizing elements are usually manufactured through the following steps: a step of uniaxially stretching the polyvinyl alcohol-based resin film; and a step of dyeing the polyvinyl alcohol-based resin film with a dichroic pigment to adsorb the dichroic pigment. ; A step of treating a polyvinyl alcohol-based resin film adsorbed with a dichroic pigment using a boric acid aqueous solution; and a step of treating it with a boric acid aqueous solution and then washing it with water. Furthermore, the polyvinyl alcohol-based resin film is dyed with a dichroic dye, whereby the dichroic dye is contained in the polyvinyl alcohol-based resin film. When the polarizing element is manufactured using this manufacturing method, the polarizing element becomes an extended polyvinyl alcohol-based resin film containing a dichroic dye.

The uniaxial stretching of the polyvinyl alcohol resin film can be performed before dyeing with a dichroic dye, or can be performed simultaneously with dyeing or after dyeing. When the uniaxial stretching is performed after dyeing, the uniaxial stretching can be performed before the boric acid treatment or during the boric acid treatment. The uniaxial stretching can also be performed in these multiple stages. During the uniaxial stretching, the uniaxial stretching can be performed between rolls with different peripheral speeds, or can be performed using a hot roll. In addition, the uniaxial stretching can be dry stretching performed in the atmosphere, or can be wet stretching performed in a state where the polyvinyl alcohol resin film is swollen using a solvent. From the perspective of suppressing the deformation of the polarizing element, the stretching ratio is preferably 8 times or less, more preferably 7.5 times or less, and further preferably 7 times or less. In addition, from the perspective of showing the function as a polarizing element, the stretching ratio is usually 4.5 times or more. By setting the stretching ratio to the above range, the time-dependent deformation of the polarizing element can be suppressed.

An example of a method for dyeing a polyvinyl alcohol-based resin film using a dichroic dye is a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. As the dichroic dye, for example, iodine or a dichroic dye is used. Dichroic dyes include dichroic direct dyes including disazo compounds such as C.I.DIRECT RED 39 and dichroic direct dyes including trisazo and tetrasazo compounds. Furthermore, it is preferable that the polyvinyl alcohol-based resin film is immersed in water in advance before the dyeing process.

When iodine is used as a dichroic dye, a polyvinyl alcohol-based resin film is usually dyed by immersing it in an aqueous solution containing iodine and potassium iodide. The iodine content in the aqueous solution is usually from 0.01 to 1 part by mass per 100 parts by mass of water. In addition, the content of potassium iodide is usually from 0.5 to about 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution used for dyeing is usually above 20°C and below 40°C. In addition, the immersion time (dyeing time) in the aqueous solution is usually from 20 seconds to about 1,800 seconds. Furthermore, before immersing the polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide, the polyvinyl alcohol-based resin film may be immersed in water in order to swell the polyvinyl alcohol-based resin film and facilitate dyeing. The temperature of the immersion treatment is usually 20°C or more and 80°C or less, preferably 30°C or more and 60°C or less. The immersion time (dying time) is usually 20 seconds or more and 1,800 seconds or less.

On the other hand, when a dichroic organic dye is used as a dichroic pigment, a method of dyeing is usually adopted in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing a water-soluble dichroic dye. The content of the dichroic organic dye in the aqueous solution is usually 1× ^10-4 mass parts to about 10 mass parts per 100 mass parts of water, preferably 1× ^10-3 mass parts to about 1 mass part, and further preferably 1× ^10-3 mass parts to about 1× ^10-2 mass parts. The aqueous solution may also contain an inorganic salt such as sodium sulfate as a dyeing auxiliary. The temperature of the dichroic dye aqueous solution used for dyeing is usually 20°C to about 80°C. In addition, the immersion time (dyeing time) in the aqueous solution is usually 10 seconds to about 1,800 seconds.

Boric acid treatment after dyeing with a dichroic pigment can usually be performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid aqueous solution. The boric acid content in the boric acid aqueous solution is usually from 2 to 15 parts by mass per 100 parts by mass of water, preferably from 5 to 12 parts by mass. When iodine is used as a dichroic dye, the boric acid aqueous solution preferably contains potassium iodide. In this case, the content of potassium iodide is usually 0.1 to 15 parts by mass per 100 parts by mass of water, preferably 5 More than 12 parts by mass and less than 12 parts by mass. The immersion time in the boric acid aqueous solution is usually not less than 60 seconds and not more than about 1,200 seconds, preferably not less than 150 seconds and not more than 600 seconds, and more preferably not less than 200 seconds and not more than 400 seconds. The temperature of boric acid treatment is usually 50°C or higher, preferably 50°C or higher and 85°C or lower, and further preferably 60°C or higher and 80°C or lower.

The polyvinyl alcohol resin film treated with boric acid is usually washed with water. The water washing treatment can be performed, for example, by immersing the boric acid-treated polyvinyl alcohol-based resin film in water. The temperature of water in the water washing process is usually above 5°C and below 40°C. In addition, the immersion time is usually from 1 second to approximately 120 seconds.

After washing with water, a drying process is performed, and the polarizing element 20 is obtained. The drying process can be performed using a hot air dryer or a far-infrared heater, for example. The temperature of the drying process is usually 30°C or more and about 100°C or less, preferably 50°C or more and 80°C or less. The time of the drying process is usually not less than 60 seconds and not more than about 600 seconds, preferably not less than 120 seconds and not more than about 600 seconds. Through the drying process, the moisture content of the polarizing element is reduced to the actual use level. The moisture content is usually 5 mass% or more and about 20 mass% or less, preferably 8 mass% or more and 15 mass% or less. If the moisture content is within the above range, a polarizing element having moderate flexibility and excellent thermal stability can be easily obtained.

The thickness of the polarizing element 20 is preferably not less than 5 μm and not more than 40 μm, and more preferably not less than 5 μm and not more than 20 μm.

(4) Optically anisotropic layer and alignment layer The optically anisotropic layer 30 is an optically anisotropic layer (hereinafter also referred to as "liquid crystal cured film") of a polymer formed by coating a composition containing a polymerizable liquid crystal compound (hereinafter also referred to as "liquid crystal cured film forming composition") on a transparent substrate and aligning the polymerizable liquid crystal compound. By making the optically anisotropic layer 30 a liquid crystal cured film, it is possible to achieve thinning and arbitrarily design wavelength dispersion characteristics. In addition, the liquid crystal cured film forming composition may further include a solvent, a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, a leveling agent, and an adhesion enhancer.

The liquid crystal cured film is usually formed by coating a composition for forming a liquid crystal cured film on an alignment layer formed on a substrate, and polymerizing the polymerizable liquid crystal compound contained in the composition for forming a liquid crystal cured film. The liquid crystal cured film is usually a film formed by curing the polymerizable liquid crystal compound in an aligned state. In order to generate a phase difference in the viewing surface, the liquid crystal cured film needs to be a cured film formed by polymerizing the polymerizable group in a state where the polymerizable liquid crystal compound is aligned in a horizontal direction relative to the substrate surface. At this time, when the polymerizable liquid crystal compound is a rod-shaped liquid crystal, it can be a positive A plate, and when the polymerizable liquid crystal compound is a disc-shaped liquid crystal, it can be a negative A plate.

The liquid crystal cured film can be a λ/4 layer, a λ/2 layer, or a positive C layer. The optically anisotropic layer 30 may also include two or more layers of liquid crystal cured films. Examples of a combination of two or more layers of liquid crystal cured film include a combination of a λ/4 layer and a λ/2 layer, a combination of a λ/4 layer and a positive C layer, and the like. From the perspective of achieving a high degree of anti-reflection function, it is sufficient to have a λ/4 plate function (that is, a phase difference function of π/2) in the entire visible light range. Specifically, a reverse wavelength dispersion λ/4 layer is preferred, but a combination of a positive wavelength dispersion λ/2 layer and a positive wavelength dispersion λ/4 layer may also be used. Furthermore, from the viewpoint of compensating the anti-reflection function in the oblique direction, it is preferable to further include a layer (positive C plate) having anisotropy in the thickness direction. In addition, each optically anisotropic layer may be tilted or may be in a cholesterol-aligned state. When the optically anisotropic layer 30 includes two or more layers of liquid crystal cured films, the optically anisotropic layer 30 may also include a bonding layer (adhesive layer or adhesive) for bonding the liquid crystal cured films to each other. layer).

The in-plane phase difference value of the optically anisotropic layer 30 with respect to light of wavelength λ nm, that is, Re(λ), preferably satisfies the following equation (1), more preferably further satisfies the following equation (1), the following equation (2) and the following formula (3). 100 nm≦Re(550)≦160 nm・・・(1) (In the formula, Re(550) represents the in-plane phase difference (in-plane retardation) for light with a wavelength of 550 nm) Re(450)/Re(550)≦1.0・・・(2) 1.00≦Re(650)/Re(550)・・(3) (In the formula, Re(450) represents the in-plane phase difference value for the light with a wavelength of 450 nm, Re(550) represents the in-plane phase difference value for the light with a wavelength of 550 nm, and Re(650) represents the in-plane phase difference value for the light with a wavelength of 650 nm. In-plane phase difference value of light)

If the optical anisotropic layer 30 satisfies formula (1), when the optical multilayer (elliptical polarizer) including the optical anisotropic layer 30 is applied to an image display device such as an organic EL display device, the front reflection hue during black display can be easily improved. The Re (550) of the optical anisotropic layer 30 is more preferably not less than 130 nm and not more than 150 nm.

The optically anisotropic layer 30 preferably has reverse wavelength dispersion, and specifically, it is preferred that the optically anisotropic layer 30 satisfies equations (2) and (3). If the value of "Re(450)/Re(550)" of the optically anisotropic layer 30 exceeds 1.0, the light leakage on the short wavelength side of the elliptically polarizing plate provided with the optically anisotropic layer will increase. The value of "Re(450)/Re(550)" is preferably 0.7 or more and 1.0 or less, more preferably 0.80 or more and 0.95 or less, further preferably 0.80 or more and 0.92 or less, particularly preferably 0.82 or more and 0.88 or less. The value of "Re(450)/Re(550)" can be arbitrarily adjusted by adjusting the mixing ratio of the polymerizable liquid crystal compound or the lamination angle or phase difference value of a plurality of liquid crystal cured films.

The in-plane phase difference value Re(λ) of the optical anisotropic layer 30 can be adjusted according to the thickness of the optical anisotropic layer 30. Since the in-plane phase difference value Re(λ) is determined by the following formula (4), in order to obtain the desired in-plane phase difference value Re(λ), Δn(λ) and the film thickness d can be adjusted. The thickness of the optical anisotropic layer 30 can be measured by an interference film thickness meter, a laser microscope or a stylus film thickness meter. In addition, Δn(λ) depends on the molecular structure of the following polymerizable liquid crystal compound. Re(λ)＝d×Δn(λ) ・・・(4) (In the formula, Re(λ) represents the in-plane phase difference value at a wavelength of λ nm, d represents the film thickness, and Δn(λ) represents the birefringence at a wavelength of λ nm)

Furthermore, the phase difference value Rth(550) in the thickness direction of the positive C layer at a wavelength of 550 nm is usually in the range of -170 nm to -10 nm, preferably -150 nm to -20 nm, and more preferably -100 nm to -40 nm. If the phase difference value in the thickness direction is within this range, the characteristic of preventing reflection from an oblique direction can be further improved.

The so-called polymerizable liquid crystal compound refers to a liquid crystal compound having a polymerizable group, especially a photopolymerizable group. As the polymerizable liquid crystal compound, for example, a previously known polymerizable liquid crystal compound can be used in the field of phase difference film. The so-called photopolymerizable group refers to a group that can participate in the polymerization reaction through a reactive species generated from a photopolymerization initiator, such as an active free radical or an acid. As the photopolymerizable group, there can be cited: vinyl, vinyloxy, 1-vinyl chloride, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, ethylene oxide, cyclobutylene oxide, etc. Among them, acryloxy, methacryloxy, vinyloxy, ethylene oxide and cyclobutylene oxide are preferred, and acryloxy is more preferred. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal. Thermotropic liquid crystal is preferred in terms of being able to closely control the film thickness. In addition, as the phase sequence structure in the thermotropic liquid crystal, it may be a nematic liquid crystal or a lamellar liquid crystal. In addition, it may be a rod-shaped liquid crystal or a disc-shaped liquid crystal. The polymerizable liquid crystal compound may be used alone or in combination of two or more.

The polymerizable liquid crystal compound is preferably a T-shaped or H-shaped liquid crystal primordial structure having birefringence in a direction perpendicular to the long axis of the molecule from the viewpoint of exhibiting reverse wavelength dispersion. From the viewpoint of obtaining stronger dispersion, the liquid crystal is more preferably a T-shaped liquid crystal. Specific examples of the structure of the T-shaped liquid crystal include compounds represented by the following formula (I). [Chemical 1]

In formula (I), Ar represents a divalent aromatic group which may have a substituent. The divalent aromatic group preferably contains at least one of a nitrogen atom, an oxygen atom, and a sulfur atom. When the divalent group Ar contains two or more aromatic groups, the two or more aromatic groups may be bonded to each other via a single bond, -CO-O-, -O- or other divalent bonding groups. ^G1 and ^G2 each independently represent a divalent aromatic group or a divalent alicyclic alkyl group. Here, the hydrogen atom contained in the divalent aromatic group or the divalent alicyclic alkyl group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and the carbon atom constituting the divalent aromatic group or the divalent alicyclic alkyl group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom. L ¹ , L ² , B ¹ and B ² are each independently a single bond or a divalent linking group. k and l are each independently an integer of 0 to 3 and satisfy the relationship of 1≦k+1. Here, when 2≦k+1, B ¹ and B ² , G ¹ and G ² may be the same or different from each other. E ¹ and E ² are each independently an alkanediyl group having 1 to 17 carbon atoms. Here, the hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and the -CH ₂ - contained in the alkanediyl group may be substituted with -O-, -S-, or -C(=O). When there are plural -O-, -S-, or -COO-, they are not adjacent to each other. P ¹ and P ² are each independently a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

^G1 and ^G2 are each independently preferably 1,4-phenylenediyl which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, 1,4-cyclohexanediyl which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably 1,4-phenylenediyl substituted with methyl, unsubstituted 1,4-phenylenediyl or unsubstituted 1,4-trans-cyclohexanediyl, and particularly preferably unsubstituted 1,4-phenylenediyl or unsubstituted 1,4-trans-cyclohexanediyl. Furthermore, it is preferred that at least one of the multiple ^G1 and ^G2 is a divalent alicyclic hydrocarbon group, and it is more preferred that at least one of ^G1 and ^G2 bonded to ^L1 or ^L2 is a divalent alicyclic hydrocarbon group.

^L1 and ^L2 are each independently preferably ^a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, ^-S- , ^-Ra1ORa2- , -Ra3COORa4-, -Ra5OCORa6-, Ra7OC= ^OORa8- , -N=N-, ^-CRc = ^CRd- , or -C≡C-. Here, ^Ra1 to ^Ra8 are each independently a single bond or an alkylene group ^{having 1} to 4 carbon atoms, and ^Rc and ^Rd are each a alkyl group having 1 to 4 carbon atoms or a hydrogen atom. ^L1 and ^L2 are each independently more preferably a single bond _, ^-ORa2-1- , ^{-CH2- ,} _{-CH2CH2- ,} ^-COORa4-1- , or ^-OCORa6-1- . Here, ^Ra2-1 , ^Ra4-1 , and ^Ra6-1 each independently represent a single bond, _-CH2- , or _-CH2CH2- . ^L1 and ^L2 each independently represent preferably a _single bond, _-O- , _-CH2CH2- , -COO- _{, -COOCH2CH2-} , or -OCO-.

^B1 and ^B2 are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a9 OR ^a10 -, -R ^a11 COOR ^a12 -, -R ^a13 OCOR ^a14 -, or -R ^a15 OC=OOR ^a16 -. Here, R ^a9 to R ^a16 are each independently a single bond or an alkylene group having 1 to 4 carbon atoms. ^B1 and ^B2 are each independently more preferably a single bond, -OR ^a10-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a12-1 -, or -OCOR ^a14-1 -. Here, R ^a10-1 , R ^a12-1 , and R ^a14-1 are each independently a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. ^B1 and ^B2 are each independently preferably _a single bond, -O-, _-CH2CH2- , _-COO- , _-COOCH2CH2- , _-OCO- , or _-OCOCH2CH2- .

From the viewpoint of expressing reverse wavelength dispersion, k and l are preferably in the range of 2≦k+l≦6, k+l=4 is preferable, and k=2 and l=2 are more preferable. If k=2 and l=2, it is a symmetrical structure, which is preferable.

E ¹ and E ² are each independently preferably an alkanediyl group having 1 to 17 carbon atoms, more preferably an alkanediyl group having 4 to 12 carbon atoms.

Examples of the polymerizable group represented by ^P1 or ^P2 include epoxy, vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, oxirane, and cyclobutylene. Among them, acryloxy, methacryloxy, vinyloxy, oxirane, and cyclobutylene are preferred, and acryloxy is more preferred.

Ar preferably has at least one selected from the group consisting of an aromatic hydrocarbon ring that may have a substituent, an aromatic heterocyclic ring that may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, an anthracene ring, and the like, and a benzene ring and a naphthalene ring are preferred. Examples of the aromatic heterocyclic ring include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyridine ring, a pyrimidine ring, a triazole ring, and a triazole ring. ring, pyrroline ring, imidazole ring, pyrazole ring, thiazole ring, benzothiazole ring, thienothiazole, 㗁azole ring, benzothezole ring, and phenanthroline ring, etc. Among them, one having a thiazole ring, a benzothiazole ring or a benzofuran ring is preferred, and one having a benzothiazolyl group is more preferred. Moreover, when Ar contains a nitrogen atom, it is preferable that the nitrogen atom has π electrons.

In formula (I), the total number Nπ of π electrons contained in the divalent aromatic group represented by Ar is usually 6 or more, preferably 8 or more, more preferably 10 or more, further preferably 14 or more, and particularly preferably 16 or more. Furthermore, the total number Nπ is preferably 30 or less, more preferably 26 or less, and further preferably 24 or less.

As the aromatic group represented by Ar, for example, the following groups are suitably exemplified.

[Chemicalization 2]

In the formula (Ar-1) to the formula (Ar-23), the * symbol represents a connecting part, and Z ⁰ , Z ¹ and Z ² each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, and a cyano group. , nitro group, alkylsulfenyl group with 1 to 12 carbon atoms, alkylsulfenyl group with 1 to 12 carbon atoms, carboxyl group, fluoroalkyl group with 1 to 12 carbon atoms, alkoxy group with 1 to 6 carbon atoms , Alkylthio group with 1 to 12 carbon atoms, N-alkylamino group with 1 to 12 carbon atoms, N,N-dialkylamino group with 2 to 12 carbon atoms, N-alkyl group with 1 to 12 carbon atoms Aminosulfonyl group or N,N-dialkylaminesulfonyl group having 2 to 12 carbon atoms.

Q ¹ , Q ² and Q ³ each independently represent -CR ^2' R ^3' -, -S-, -NH-, -NR ^2' -, -CO- or -O-, and R ^2' and R ^3' each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

J ¹ and J ² each independently represent a carbon atom or a nitrogen atom.

Y ¹ , Y ² and Y ³ each independently represent an aromatic alkyl group or an aromatic heterocyclic group which may be substituted.

W ¹ and W ² each independently represent a hydrogen atom, a cyano group, a methyl group or a halogen atom, and m represents an integer from 0 to 6.

Examples of the aromatic hydrocarbon group in Y ¹ , Y ² and Y ³ include aromatic hydrocarbon groups having 6 to 20 carbon atoms such as phenyl, naphthyl, anthracenyl, phenanthrenyl, and biphenyl groups. Preferred ones are phenyl, Naphthyl, more preferably phenyl. Examples of the aromatic heterocyclic group include furyl, pyrrolyl, thienyl, pyridyl, thiazolyl, benzothiazolyl and other carbon atoms containing at least one heteroatom such as nitrogen atom, oxygen atom, sulfur atom and the like. The aromatic heterocyclic group of ~20 is preferably furyl, thienyl, pyridyl, thiazolyl or benzothiazolyl.

Y ¹ , Y ² and Y ³ may each independently be a substituted polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from a collection of aromatic rings. The polycyclic aromatic heterocyclic group refers to a condensed polycyclic aromatic heterocyclic group or a group derived from a collection of aromatic rings.

It is preferable that Z ⁰ , Z ¹ and Z ² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, or an alkoxy group having 1 to 12 carbon atoms, and more preferably Z ⁰ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a cyano group, and more preferably Z ¹ and Z ² are a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a cyano group.

Q ¹ , Q ² and Q ³ are preferably -NH-, -S-, -NR ^2' -, or -O-, and R ^{2 '} is preferably a hydrogen atom. Among them, -S-, -O-, or -NH- is particularly preferred.

Among formulas (Ar-1) to (Ar-23), from the viewpoint of molecular stability, formula (Ar-6) and formula (Ar-7) are preferred.

In the formulas (Ar-16) to (Ar-23), Y ¹ can form an aromatic heterocyclic group together with its bonded nitrogen atom and Z ⁰ . Examples of the aromatic heterocyclic group include those described above as aromatic heterocyclic rings that Ar may have. Examples include: pyrrole ring, imidazole ring, pyrroline ring, pyridine ring, pyridine ring, and pyrimidine. ring, indole ring, quinoline ring, isoquinoline ring, purine ring, pyrrolidine ring, etc. The aromatic heterocyclic group may have a substituent. In addition, Y ¹ may also be the above-mentioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ⁰ . Examples thereof include benzofuran ring, benzothiazole ring, benzothezole ring, and the like.

Among polymerizable liquid crystal compounds, compounds having a maximum absorption wavelength of 300 nm to 400 nm are preferred. When a photopolymerization initiator is included in a composition for forming a liquid crystal cured film, there is a concern that the polymerization reaction and gelation of the polymerizable liquid crystal compound may proceed during long-term storage. However, if the maximum absorption wavelength of the polymerizable liquid crystal compound is 300 nm to 400 nm, even if it is exposed to ultraviolet light during storage, the generation of reactive species from the photopolymerization initiator and the polymerization reaction and gelation of the polymerizable liquid crystal compound by the reactive species can be effectively suppressed. Therefore, it becomes advantageous in terms of the long-term stability of the composition for forming a liquid crystal cured film, and the orientation and uniformity of the film thickness of the obtained liquid crystal cured film can be improved. Furthermore, the maximum absorption wavelength of the polymerizable liquid crystal compound can be measured in a solvent using an ultraviolet-visible spectrophotometer. The solvent is a solvent that can dissolve the polymerizable liquid crystal compound, and examples thereof include chloroform.

The content of the polymerizable liquid crystal compound in the composition for forming a liquid crystal cured film is, for example, 70 parts by mass or more and 99.5 parts by mass or less, preferably 80 parts by mass or more, relative to 100 parts by mass of the solid content of the composition for forming a liquid crystal cured film. 99 parts by mass or less, more preferably not less than 85 parts by mass and not more than 98 parts by mass, still more preferably not less than 90 parts by mass and not more than 95 parts by mass. If the content of the polymerizable liquid crystal compound is within the above range, it is advantageous from the viewpoint of the alignment of the obtained optically anisotropic layer. In addition, in this specification, the solid content of the composition for liquid crystal cured film formation means all components obtained by removing volatile components such as organic solvents from the composition for liquid crystal cured film formation.

The composition for forming a liquid crystal cured film may contain, in addition to the polymerizable liquid crystal compound, a solvent, a polymerization initiator, a leveling agent, an antioxidant, a photosensitizer, a reactive additive, a vertical alignment promoter, a polymerizable non-liquid crystal compound and other additives. These components may be used alone or in combination of two or more.

The composition for forming a liquid crystal curable film is usually applied to a substrate film or the like in a state of being dissolved in a solvent, so it is preferred to include a solvent. Generally speaking, since polymerizable liquid crystal compounds have a high viscosity, it is easy to apply by dissolving them in a solvent to form a liquid crystal curable film composition, and as a result, an optically anisotropic layer is easily formed in most cases. As a solvent, it is preferred that the polymerizable liquid crystal compound be completely dissolved, and it is preferred that the solvent be inert to the polymerization reaction of the polymerizable liquid crystal compound. In addition, it is preferred that the solvent not dissolve the substrate film used. Examples of the solvent include alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy-2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; Ketone solvents such as butyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; aliphatic hydrocarbon solvents such as ethylcyclohexane; aromatic hydrocarbon solvents such as toluene, xylene and anisole; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone, etc. These solvents may be used alone or in combination of two or more. Among them, from the viewpoint of film coating, it is preferred to use at least one selected from alcohol solvents, ester solvents, ketone solvents, chlorine-containing solvents, amide solvents and aromatic hydrocarbon solvents, and from the viewpoint of the solubility of polymerizable liquid crystal compounds, it is more preferred to use at least one selected from ester solvents, ketone solvents, amide solvents and aromatic hydrocarbon solvents.

The content of the solvent in the liquid crystal curing film forming composition is preferably 50 to 98 parts by mass, more preferably 70 to 95 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal composition. Therefore, the solid content of 100 parts by mass of the liquid crystal curing film forming composition is preferably 2 to 50 parts by mass, more preferably 5 to 30% by mass. If the solid content is 50 parts by mass or less, the viscosity of the liquid crystal curing film forming composition decreases, so the thickness of the film tends to be roughly uniform and less prone to unevenness. The above solid content can be appropriately determined in consideration of the thickness of the liquid crystal curing film to be produced.

The polymerization initiator is a compound that generates reactive species by the action of heat or light and can initiate the polymerization reaction of a polymerizable liquid crystal compound or the like. Examples of reactive species include free radicals, cations, anions, and the like. Among them, from the perspective of easy control of the reaction, a photopolymerization initiator that generates free radicals by light irradiation is preferred.

As the photopolymerization initiator, any known photopolymerization initiator can be used as long as it is a compound that can start the polymerization reaction of the polymerizable liquid crystal compound. Specifically, a photopolymerization initiator that generates active radicals or acid by the action of light can be exemplified. Among them, a photopolymerization initiator that generates radicals by the action of light is preferred. The photopolymerization initiator can be used alone or in combination of two or more.

As the photopolymerization initiator, a known photopolymerization initiator can be used. For example, as the photopolymerization initiator for generating active free radicals, self-cleaving type benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, azo compounds, etc. can be used. Hydrogen-absorbent type benzophenone compounds, phenylalanone compounds, benzoin ether compounds, benzyl ketone compounds, dibenzocycloheptanone compounds, anthraquinone compounds, oxadione compounds, 9-oxothiophenone compounds can be used. As the photopolymerization initiator for generating an acid, iodonium salts and coronium salts can be used. From the viewpoint of excellent reaction efficiency at low temperature, a self-cleaving type photopolymerization initiator is preferred, and acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, and oxime ester compounds are particularly preferred.

The photopolymerization initiator contained in the liquid crystal cured film forming composition is at least one kind, and a plurality of kinds may be used in combination, and may be appropriately selected according to the relationship with the polymerizable liquid crystal compound contained in the liquid crystal cured film forming composition.

The content of the polymerization initiator in the composition for forming a liquid crystal cured film can be appropriately adjusted according to the type and amount of the polymerizable liquid crystal compound. It is usually 0.1 parts by mass or more and 30 parts by mass relative to 100 parts by mass of the content of the polymerizable liquid crystal compound. parts or less, preferably 0.5 parts by mass or more and 10 parts by mass or less, more preferably 0.5 parts by mass or more and 8 parts by mass or less. If the content of the polymerization initiator is within the above range, polymerization can be performed without disturbing the alignment of the polymerizable liquid crystal compound.

The leveling agent is an additive that has the function of adjusting the fluidity of the liquid crystal curing film forming composition to make the coating obtained by applying the liquid crystal curing film forming composition flatter. For example, it is preferably a polymer component containing fluorine atoms or silicon atoms or a polyacrylate polymer, and it is more preferably a surfactant with a polymer component containing fluorine atoms or silicon atoms as the main component. Specifically, organically modified polysilicone oil-based, polyacrylate-based, and perfluoroalkyl-based leveling agents can be cited. Among them, polyacrylate-based leveling agents and perfluoroalkyl-based leveling agents are preferred.

The content of the leveling agent is preferably from 0.01 to 5 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, more preferably from 0.05 to 3 parts by mass, and still more preferably from 0.05 to 1 part by mass. the following. If the content of the leveling agent is within the above range, the polymerizable liquid crystal compound will be easily aligned, and the obtained optically anisotropic layer 30 will tend to become smoother. If the content of the leveling agent relative to the polymerizable liquid crystal compound exceeds the above range, the obtained optically anisotropic layer 30 tends to be uneven. The liquid crystal cured film forming composition may contain two or more leveling agents.

By formulating an antioxidant, the polymerization reaction of the polymerizable liquid crystal compound can be controlled. The antioxidant may be a primary antioxidant selected from the group consisting of phenolic antioxidants, amine antioxidants, quinone antioxidants, and nitroso antioxidants, or may be a primary antioxidant selected from the group consisting of phosphorus antioxidants and sulfur antioxidants. Among the secondary antioxidants. In order to polymerize the polymerizable liquid crystal compound without disturbing the alignment of the polymerizable liquid crystal compound, the content of the antioxidant is usually from 0.01 to 10 parts by mass, preferably from 0.1 to 100 parts by mass of the polymerizable liquid crystal compound. The amount is not less than 5 parts by mass and not more than 5 parts by mass, and more preferably not less than 0.1 parts by mass and not more than 3 parts by mass. Antioxidants can be used alone or in combination of two or more types.

By using a photosensitizer, the photopolymerization initiator can be made highly sensitive. Examples of photosensitizers include: ketone and 9-oxysulfide Such as ketones; anthracenes, alkyl ethers and other substituted anthracenes; thiophene; rubrene. A photosensitizer can be used individually or in combination of 2 or more types. The content of the photosensitizer is usually from 0.01 to 10 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, preferably from 0.05 to 5 parts by mass, and more preferably from 0.1 to 3 parts by mass.

The liquid crystal cured film-forming composition for forming a liquid crystal cured film can be obtained by stirring a polymerizable liquid crystal compound and components such as a solvent or a polymerization initiator at a specific temperature.

The liquid crystal cured film can be manufactured, for example, by a method comprising the following steps: Forming a coating of a liquid crystal cured film forming composition containing at least one polymerizable liquid crystal compound on a substrate film or the alignment layer 60 described below, drying the coating, and aligning the polymerizable liquid crystal compound in the liquid crystal cured film forming composition; and Directly polymerizing the polymerizable liquid crystal compound while maintaining the alignment state to form a liquid crystal cured film.

The coating film of the liquid crystal cured film forming composition can be formed by applying the liquid crystal cured film forming composition on the base film or the alignment layer 60 or the like formed on the base film. Examples of methods for applying the composition for forming a liquid crystal cured film to a base film or the like include spin coating, extrusion coating, gravure coating, die coating, and rod coating. , coating methods such as the applicator method, printing methods such as the flexographic method, and other well-known methods.

As the substrate film, glass substrate and film substrate can be cited, preferably film substrate, and more preferably long roll film substrate in terms of continuous production. As the resin constituting the film substrate, for example, polyolefins such as polyethylene, polypropylene, and norolefin polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylate; polyacrylate; cellulose esters of triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyetherketone; polyphenylene sulfide and polyphenylene ether and other plastics can be cited. Among them, from the viewpoint of transparency when used for optical films, a film substrate made of any one of triacetyl cellulose, cyclic olefin resin, polymethacrylate, and polyethylene terephthalate is more preferred.

From the viewpoint of operability, processability, strength, etc., the thickness of the base film is usually 5 μm or more and 300 μm or less, preferably 10 μm or more and 200 μm or less, more preferably 10 μm or more and 50 μm or less.

Then, the solvent is removed by drying, etc., thereby forming a dry coating. Examples of drying methods include natural drying, ventilation drying, heating drying, and reduced pressure drying. At this time, by heating the coating obtained from the composition for forming a liquid crystal curing film, the solvent can be dried and removed from the coating, and the polymerizable liquid crystal compound can be aligned in a desired direction such as a horizontal direction relative to the coating plane. The heating temperature of the coating can be appropriately determined in consideration of the polymerizable liquid crystal compound used and the material of the substrate film forming the coating, etc. In order to make the polymerizable liquid crystal compound transition to the liquid crystal phase state, a temperature above the liquid crystal phase transition temperature is generally required. In order to remove the solvent contained in the liquid crystal curing film forming composition while making the polymerizable liquid crystal compound into the desired alignment state, for example, the temperature can be heated to a temperature above the liquid crystal phase transition temperature (smectic phase transition temperature or nematic phase transition temperature) of the polymerizable liquid crystal compound contained in the liquid crystal curing film forming composition. The upper limit of the heating temperature is not particularly limited, but in order to avoid damage to the coating film or substrate film due to heating, it is preferably below 180°C, and more preferably below 150°C.

Furthermore, the liquid crystal phase transition temperature can be measured, for example, using a polarizing microscope equipped with a temperature control stage, a differential scanning calorimeter (DSC), a thermogravimetric differential thermal analyzer (TG-DTA), etc. In addition, when two or more polymerizable liquid crystal compounds are used in combination, the above-mentioned phase transition temperature means a mixture of polymerizable liquid crystal compounds formed by mixing all polymerizable liquid crystal compounds constituting the liquid crystal curing film forming composition in the same ratio as the composition in the liquid crystal curing film forming composition, and the temperature measured in the same manner as when one polymerizable liquid crystal compound is used. In addition, in general, it is also known that the liquid crystal phase transition temperature of the polymerizable liquid crystal compound in the liquid crystal curing film forming composition is sometimes lower than the liquid crystal phase transition temperature of the polymerizable liquid crystal compound as a single substance.

The heating time can be appropriately determined according to the heating temperature, the type of polymerizable liquid crystal compound used, the type of solvent or its boiling point and its amount, and is usually 0.5 to 10 minutes, preferably 0.5 to 5 minutes.

The operation of removing the solvent from the coating film may be performed simultaneously with the operation of heating the polymerizable liquid crystal compound to a temperature higher than the liquid crystal phase transition temperature, or may be performed separately. From the viewpoint of improving productivity, it is preferably performed simultaneously. Before performing the operation of heating the polymerizable liquid crystal compound to a temperature higher than the liquid crystal phase transition temperature, a predrying step may be provided. The predrying step is used to polymerize the coating film obtained from the composition for forming a liquid crystal cured film. The solvent in the coating film can be appropriately removed under the condition that the liquid crystal compound will not polymerize. Examples of drying methods in the pre-drying step include natural drying, ventilation drying, heating drying, and reduced pressure drying.

Then, in the obtained dry coating film, the alignment state of the polymerizable liquid crystal compound is maintained and the polymerizable liquid crystal compound is polymerized by light irradiation, thereby forming a polymer of the polymerizable liquid crystal compound existing in the desired alignment state. LCD hardened film. As a polymerization method, a photopolymerization method is usually used. In photopolymerization, the light irradiated to the dry coating film depends on the type of photopolymerization initiator contained in the dry coating film and the type of polymerizable liquid crystal compound (especially the polymerizability of the polymerizable liquid crystal compound). The type of base) and its amount should be selected appropriately. Specific examples thereof include one or more types of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays and γ-rays, or active energy rays such as active electron beams. Among them, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction or can be used as a photopolymerization device that is widely used in this field, and it is preferred that the photopolymerization can be carried out by ultraviolet light in advance. Select the type of polymerizable liquid crystal compound or photopolymerization initiator. Furthermore, during polymerization, the polymerization temperature can also be controlled by irradiating light while cooling the dry coating film with an appropriate cooling mechanism. By employing such a cooling mechanism, as long as the polymerizable liquid crystal compound is polymerized at a lower temperature, even if a base material film having relatively low heat resistance is used, a liquid crystal cured film can be formed appropriately. In addition, the polymerization reaction can also be accelerated by raising the polymerization temperature within a range that does not cause problems (deformation of the base film due to heat, etc.) due to heat during light irradiation. During photopolymerization, a patterned cured film can also be obtained by performing masking or development.

Examples of the light source of the active energy line include 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 Emitting Diode) light sources emitting light in a wavelength range of 380 nm to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

The intensity of ultraviolet irradiation is usually 10 mW/cm ² or more and 3,000 mW/cm ² or less. The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating the photopolymerization initiator. The time of irradiation with light is usually 0.1 second or more and 10 minutes or less, preferably 0.1 second or more and 5 minutes or less, more preferably 0.1 second or more and 3 minutes or less, and still more preferably 0.1 second or more and 1 minute or more. If irradiated once or multiple times with this ultraviolet irradiation intensity, the cumulative light amount is 10 mJ/cm ² or more and 3,000 mJ/cm ² or less, preferably 50 mJ/cm ² or more and 2,000 mJ/cm ² or less, more preferably 100 mJ/cm ² or more and 1,000 mJ/cm ² or less.

The thickness of the optical anisotropic layer 30 (or each layer when two or more liquid crystal cured films are included) is 0.1 μm to 5 μm, preferably 0.5 μm to 3 μm, more preferably 1.0 μm, more preferably 1.5 μm, and more preferably 2.5 μm. If the film thickness of the liquid crystal cured film is within the above range, it is easy to show specific optical properties and to improve the flexibility of the optical layer. The thickness of the liquid crystal cured film can be measured using an interference film thickness meter, a laser microscope, or a stylus film thickness meter.

As shown in the optical laminate 1 shown in FIG. 1 , the optical laminate of the present invention may also include an alignment layer 60. In this case, a liquid crystal cured film may be formed on the alignment layer 60. The alignment layer 60 has an alignment limiting force that allows the polymerizable liquid crystal compound to align along a desired direction. By forming a liquid crystal cured film using a horizontal alignment layer having an alignment limiting force that allows the polymerizable liquid crystal compound to align along a horizontal direction or a vertical alignment layer having an alignment limiting force that allows the polymerizable liquid crystal compound to align along a vertical direction, the polymerizable liquid crystal compound can be aligned along a desired direction with higher precision, and a liquid crystal cured film that exhibits excellent optical properties when assembled in an image display device or the like can be obtained. The alignment restraining force can be arbitrarily adjusted by the type of alignment layer, surface state or rubbing conditions, etc. When the alignment layer is formed of a photo-aligned polymer, it can be arbitrarily adjusted by polarized light irradiation conditions, etc.

The state of liquid crystal alignment such as horizontal alignment, vertical alignment, mixed alignment, tilted alignment, etc. varies according to the properties of the alignment layer 60 and the polymerizable liquid crystal compound, and the combination thereof can be selected arbitrarily. For example, if the alignment layer 60 is a material that exhibits horizontal alignment in terms of alignment restriction force, the polymerizable liquid crystal compound can form a horizontal alignment or a mixed alignment, and if the alignment layer 60 is a material that exhibits vertical alignment, the polymerizable liquid crystal compound can form a vertical alignment or a tilted alignment. Expressions such as horizontal and vertical represent the direction of the long axis of the aligned polymerizable liquid crystal compound when the plane (main surface) of the optical anisotropic layer 30 is used as a reference. For example, horizontal alignment refers to having the long axis of the aligned polymerizable liquid crystal compound in a direction perpendicular to the plane (main surface) of the optical anisotropic layer 30. Here, perpendicular means an angle of 90°±20° relative to the plane (main surface) of the optical anisotropic layer 30 .

The alignment layer preferably has solvent resistance such that it is not dissolved by application of the liquid crystal cured film forming composition, etc., and has heat resistance useful for removal of the solvent or heat treatment for alignment of the polymerizable liquid crystal compound. By. Examples of the alignment layer include: an alignment film containing an alignment polymer, a photo alignment film, a trench alignment film with a concave and convex pattern or a plurality of grooves on the surface, an extended film that extends along the alignment direction, etc., in terms of the alignment angle. From the viewpoint of accuracy and quality, a photo-alignment film is preferred.

Examples of the alignment polymer include polyamide or gelatin having an amide bond in the molecule, polyamide imine having an amide imine bond in the molecule, and polyamide acid, which is a hydrolyzate thereof, and polyethylene. Alcohol, alkyl modified polyvinyl alcohol, polyacrylamide, polyethazole, polyethylenimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylate esters. Among them, polyvinyl alcohol is preferred. Alignment polymers can be used alone or in combination of two or more types.

An alignment film containing an alignment polymer is generally obtained by applying a composition in which an alignment polymer is dissolved in a solvent (hereinafter, also referred to as an "alignment polymer composition") to a surface of a substrate film or the like on which an alignment layer is to be formed, and removing the solvent; or applying the alignment polymer composition to a substrate, removing the solvent, and rubbing (rubbing method). Examples of the solvent include the same solvents as those exemplified above as solvents that can be used in the composition for forming a liquid crystal cured film.

The concentration of the aligning polymer in the aligning polymer composition only needs to be within a range in which the aligning polymer material can be completely dissolved in the solvent. It is preferably 0.1% by mass or more relative to the solution in terms of solid content 20 mass% or less, more preferably 0.1 mass% or more and 10 mass% or less.

As a method for applying the alignment polymer composition on the surface of the substrate film or the like where the alignment layer is to be formed, the same methods as those exemplified as the method for applying the composition for forming a liquid crystal cured film on the substrate film can be cited. As a method for removing the solvent contained in the alignment polymer composition, natural drying method, ventilation drying method, heat drying method, and reduced pressure drying method can be cited.

In order to impart an alignment restricting force to the alignment layer, a rubbing treatment (rubbing method) may be performed as needed. As a method of imparting an alignment restricting force by the rubbing method, the following method may be cited: a film of an alignment polymer formed on the surface of a substrate film by coating an alignment polymer composition on a substrate film and annealing the film is brought into contact with a rubbing roller wound with a rubbing cloth and rotating. If masking is performed during the rubbing treatment, multiple regions (patterns) with different alignment directions may also be formed on the alignment layer.

Photo-alignment films are usually obtained by combining a polymer with a photoreactive group (photo-alignment polymer) and/or a monomer with a photo-reactive group (photo-alignment monomer) and a solvent. The composition (hereinafter, also referred to as "photo alignment film forming composition") is coated on the surface of the base film where the alignment layer is to be formed, the solvent is removed, and then polarized light (preferably polarized UV (ultraviolet, ultraviolet)) is irradiated. The optical alignment film can arbitrarily control the direction of the alignment restriction force by selecting the polarization direction of the irradiated polarized light, which is also advantageous in this regard.

The so-called photoreactive group refers to a group that generates the ability of liquid crystal alignment by light irradiation. Specifically, it can be cited as a group that participates in the photoreaction that becomes the origin of the liquid crystal alignment ability, such as the alignment induction or isomerization reaction, dimerization reaction, photocrosslinking reaction or photodecomposition reaction of the molecules generated by light irradiation. Among them, the base that participates in the dimerization reaction or photocrosslinking reaction is better in terms of excellent alignment. As a photoreactive group, it is preferably a group having an unsaturated bond, especially a double bond, and it is particularly preferably a group having at least one selected from the group consisting of a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond), and a carbon-oxygen double bond (C=O bond).

Examples of the photoreactive group having a C=C bond include a vinyl group, a polyalkenyl group, a stilbenyl group, a styrylpyridinyl group, a styrylpyridinium group, a chalcone group, a cinnamyl group, and the like. From the viewpoint of easily controlling the reactivity or exhibiting alignment restricting force during photo-alignment, a chalcone group and a cinnamyl group are preferred. Examples of the photoreactive group having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of the photoreactive group having an N=N bond include: azophenyl group, azonaphthyl group, aromatic heterocyclic azo group, disazo group, formazan group, and those having an oxyazobenzene structure. Zhiji et al. Examples of the photoreactive group having a C=O bond include a benzophenone group, a coumarin group, an anthraquinone group, a maleimide group, and the like. These groups may also have substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonate, and halogenated alkyl groups.

Furthermore, in order to obtain adhesiveness with the base film or the optically anisotropic layer 30, the polymer side chain having a photoreactive group may have an adhesive group. Examples of the adhesive group include an epoxy group, an oxetanyl group, a (meth)acrylyl group, and the like.

Examples of the solvent contained in the composition for forming a photo-alignment film include the same solvents as those exemplified above as solvents that can be used in the composition for forming a liquid crystal cured film. The solubility of the polymer or photoalignment monomer should be appropriately selected.

The content of the polymer or monomer having a photoreactive group in the photo-alignment film-forming composition can be appropriately adjusted according to the type of the polymer or monomer or the thickness of the target photo-alignment film, and is preferably set to at least 0.2 mass%, more preferably in the range of 0.3 mass% to 10 mass%, relative to the mass of the photo-alignment film-forming composition. The photo-alignment film-forming composition may also contain a polymer material or a photosensitizer such as polyvinyl alcohol or polyimide within a range that does not significantly damage the properties of the photo-alignment film.

As a method of applying the composition for forming a photo-alignment film to the surface of a base film or the like on which the alignment layer is to be formed, the same method as the method of applying the alignment polymer composition can be exemplified. Examples of methods for removing the solvent from the applied photo-alignment film forming composition include natural drying, ventilation drying, heat drying, and reduced pressure drying.

When irradiating with polarized light, the polarized UV light may be directly irradiated on the composition for forming a photo-alignment film coated on the substrate film after removing the solvent, or the polarized light may be irradiated from the side of the substrate film and transmitted. In addition, the polarized light is preferably substantially parallel light. The wavelength of the polarized light irradiated may be a wavelength region in which the photo-alignment polymer or the photo-alignment monomer having a photo-reactive group can absorb light energy. Specifically, UV (ultraviolet light) with a wavelength of more than 250 nm and less than 400 nm is preferred. As the light source used for the polarized light irradiation, there can be cited: xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, KrF, ArF and other ultraviolet lasers, etc.; preferably high-pressure mercury lamps, ultra-high-pressure mercury lamps and metal halide lamps. These lamps are preferred because the luminous intensity of ultraviolet light with a wavelength of 313 nm is relatively large. Polarized UV can be irradiated by passing the light from the above light sources through an appropriate polarizing element. As the polarizing element, a polarizing filter or a polarizing prism such as a Glen-Thompson prism or a Glen-Taylor prism or a wire grid type polarizing element can be used.

A groove alignment film is a film with a concave and convex pattern or a plurality of grooves (grooves) on its surface. When a polymerizable liquid crystal compound is coated on a film having a plurality of linear grooves arranged at equal intervals, the liquid crystal molecules are aligned in the direction along the grooves.

An example of a method for obtaining a trench alignment film is a method of exposing the surface of a photosensitive polyimide film through an exposure mask having patterned slits, and then developing and rinsing to form a concavo-convex pattern. ; A method of forming a UV cured resin layer before curing on a plate-shaped master with grooves on the surface, transferring the formed resin layer to a base material, etc., and then hardening it; and pressing a roll-shaped master with a plurality of grooves against Methods such as forming a film of UV curable resin on the surface of the alignment layer before curing to form unevenness, and then curing the resin.

The thickness of the alignment layer 60 (alignment film including alignment polymer or photo-alignment film, etc.) is usually 10 nm or more and 10000 nm or less, preferably 10 nm or more and 2500 nm or less, more preferably 10 nm or more and 1000 nm or less, and then The preferred range is 10 nm or more and 500 nm or less, and the particularly preferred range is 50 nm or more and 250 nm or less.

(5) First adhesive layer and second adhesive layer The transparent protective film 10 and the polarizing element 20 are laminated via the first adhesive layer 51, and only the first adhesive layer 51 is interposed between the transparent protective film 10 and the polarizing element 20. In addition, the polarizing element 20 and the optically anisotropic layer 30 are laminated via the second adhesive layer 52, and only the second adhesive layer 52 is interposed between the polarizing element 20 and the optically anisotropic layer 30. By using the first adhesive layer 51 to bond the transparent protective film 10 to the polarizing element 2, and using the second adhesive layer 52 to bond the polarizing element 20 to the optical anisotropic layer 30, the flexibility of the optical laminate can be improved, so that even if it is repeatedly bent, it is not easy to cause defects such as peeling or cracking in the bent part. In addition, by using the first adhesive layer 51 to bond the transparent protective film 10 to the polarizing element 20, and using the second adhesive layer 52 to bond the polarizing element 20 to the optical anisotropic layer 30, an optical laminate with good adhesion between the layers can be obtained.

The first adhesive layer 51 and the second adhesive layer 52 can be formed using an adhesive. Examples of the adhesive that can form the adhesive layer include dry curing adhesives such as water-based adhesives and chemical reaction adhesives such as active energy ray curing adhesives. The first adhesive layer 51 and the second adhesive layer 52 may be formed of different adhesives, but are preferably formed of the same adhesive.

Examples of the dry curing adhesive include a polymer of a monomer having a protonic functional group such as a hydroxyl group, a carboxyl group, or an amine group, and an ethylenically unsaturated group; or a polymer containing a urethane resin as a main component, and Compositions containing cross-linking agents or curing compounds such as polyhydric aldehydes, epoxy compounds, melamine compounds, zirconium oxide compounds, or zinc compounds. Examples of the polymer of a monomer having a protonic functional group such as a hydroxyl group, carboxyl group or amine group and an ethylenically unsaturated group include: ethylene-maleic acid copolymer, itaconic acid copolymer, acrylic acid copolymer, Acrylamide copolymer, saponified product of polyvinyl acetate, and polyvinyl alcohol resin, etc. Polyvinyl alcohol-based resin is preferred.

Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol, partially saponified polyvinyl alcohol, completely saponified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and hydroxymethyl-modified polyvinyl alcohol. Polyvinyl alcohol, and amine-modified polyvinyl alcohol, etc. The content of the polyvinyl alcohol-based resin in the water-based drying curable adhesive is usually 1 to 10 parts by mass, preferably 1 to 5 parts by mass relative to 100 parts by mass of water.

Examples of the urethane resin include polyester-based ionopolymer type urethane resin and the like. Here, the polyester ionopolymer type urethane resin is a urethane resin having a polyester skeleton into which a small amount of ionic components (hydrophilic components) are introduced. This ionopolymer urethane resin does not use an emulsifier, but is emulsified in water to become latex, so it can be used as a water-based drying curable adhesive. When using a polyester-based ionomer-type urethane resin, it is effective to prepare a water-soluble epoxy compound as a cross-linking agent.

Examples of epoxy resins include polyamide epoxy resins obtained by reacting epichlorohydrin with polyamide polyamines obtained by reacting polyalkylene polyamines such as diethylenetriamine or triethylenetetramine with dicarboxylic acids such as adipic acid. Examples of commercially available polyamide epoxy resins include: "Sumirez Resin (registered trademark) 650" and "Sumirez Resin (registered trademark) 675" (both manufactured by Sumika Chemtex Co., Ltd.), "WS-525" (manufactured by Japan PMC Co., Ltd.), and the like. When preparing epoxy resin, the addition amount is usually 1 to 100 parts by mass, preferably 1 to 50 parts by mass, relative to 100 parts by mass of polyvinyl alcohol resin.

Among them, the dry-curable adhesive is preferably a water-based dry-curable adhesive containing polyvinyl alcohol-based resin.

The dry curing adhesive may also contain a solvent. Examples of the solvent include water, a mixed solvent of water and a hydrophilic organic solvent (such as an alcohol solvent, an ether solvent, an ester solvent, etc.), and an organic solvent.

Active energy ray-curing adhesives, which are chemical reaction adhesives, are adhesives that are cured by irradiation with active energy rays. Active energy ray-curing adhesives may also contain solvents. Examples of active energy ray-curing adhesives include: cationic polymerizable adhesives containing epoxy compounds and cationic polymerization initiators, free radical polymerizable adhesives containing (meth)acrylic curing components and free radical polymerization initiators, adhesives containing both cationic polymerizable curing components such as epoxy compounds and free radical polymerizable curing components such as (meth)acrylic compounds, and adhesives containing cationic polymerization initiators and free radical polymerization initiators, and adhesives that do not contain these polymerization initiators and are cured by irradiation with electron beams.

Among them, the active energy ray curable adhesive is preferably a radical polymerizable active energy ray curable adhesive containing a (meth)acrylic curing component and a radical polymerization initiator, an epoxy compound and a cation Active energy ray-hardening adhesive with cationic polymerization properties as polymerization initiator. Examples of the (meth)acrylic curing component include (meth)acrylic acid esters such as methyl (meth)acrylate and hydroxyethyl (meth)acrylate, and (meth)acrylic acid. The active energy ray curable adhesive containing an epoxy compound may further contain a polymerizable compound other than the epoxy compound. Examples of polymerizable compounds other than epoxy compounds include oxetane compounds, acrylic compounds, and the like.

As the radical polymerization initiator, the photopolymerization initiator described above as the one that can be formulated in the liquid crystal cured film forming composition for forming the liquid crystal cured film can be exemplified. As the commercially available cationic polymerization initiator, the following can be exemplified: "Kayarad" (registered trademark) series (manufactured by Nippon Kayaku Co., Ltd.), "Cyracure UVI" series (manufactured by The Dow Chemical Company), "CPI" series (manufactured by SAN-APRO Co., Ltd.), "TAZ", "BBI" and "DTS" (all manufactured by Nippon Green Chemical Co., Ltd.), "Adeka Optomer" series (manufactured by ADEKA Co., Ltd.), "RHODORSIL" (registered trademark) (manufactured by Rhodia Co., Ltd.), etc. The content of the radical polymerization initiator and the cationic polymerization initiator is usually 0.5 to 20 parts by mass, preferably 1 to 15 parts by mass, relative to 100 parts by mass of the active energy ray-curable adhesive.

Compared with the case of using an adhesive layer, the transparent protective film 10 and the polarizing element 20 are bonded using the first adhesive layer 51 and the polarizing element 20 and the optical anisotropic layer 30 are bonded using the second adhesive layer 52 It is advantageous in terms of flexibility and thinning of optical laminates. From the viewpoint of improving the adhesion between the polarizing element 20 and the optically anisotropic layer 30 , the second adhesive layer 52 is preferably a layer formed of an active energy ray-curable adhesive, and more preferably a layer formed by radical polymerization. A layer formed of a radically polymerizable active energy ray-curable adhesive, and more preferably a layer formed of a radically polymerizable active energy ray-curable adhesive containing a (meth)acrylic curing component and a radical polymerization initiator. . The same applies to the first adhesive layer 51 .

The thickness of the first adhesive layer 51 and the second adhesive layer 52 is preferably 10 nm or more, more preferably 30 nm or more, more preferably 50 nm or more, preferably 5000 nm or less, more preferably 3000 nm or less, and more preferably 2000 nm or less. If the thickness of the adhesive layer, especially the second adhesive layer 52, is within the above range, it is easy to improve the flexibility of the optical laminate, so that even if it is repeatedly bent, it is not easy to cause undesirable conditions such as peeling or cracking in the bent part. The thickness of the first adhesive layer 51 and the second adhesive layer 52 can be the same or different. The thickness of the adhesive layer can be measured using, for example, an interferometer, a laser microscope, or a stylus-type film thickness gauge.

(6)Adhesive layer The optical laminate includes an adhesive layer 40 disposed on the side of the optical anisotropic layer 30 opposite to the polarizing element 20 side. The adhesive layer 40 may constitute one of the two main surfaces of the optical laminate. The adhesive layer 40 can be laminated on the side of the optical laminate opposite to the viewing side (transparent protective film 10 side), and can be used to bond the optical laminate to image display elements such as organic EL display elements.

The thickness of the adhesive layer 40 may be, for example, 150 μm or less, preferably 100 μm or less, more preferably 50 μm or less, and further preferably 40 μm or less from the viewpoint of thinness. From the viewpoint of durability, it is usually 1 μm or more, preferably 5 μm or more, and further preferably 10 μm or more.

The adhesive layer 40 may include an adhesive composition with (meth) acrylic resin, rubber resin, urethane resin, ester resin, silicone resin, or polyvinyl ether resin as the main component. Among them, the adhesive composition with (meth) acrylic resin having excellent transparency, weather resistance, heat resistance, etc. as the base polymer is preferred. The adhesive composition may be active energy ray curing type or heat curing type.

As the (meth)acrylic resin (base polymer) used in the adhesive composition, butyl (meth)acrylate, ethyl (meth)acrylate, isoacrylate (meth)acrylate can be preferably used. A polymer or copolymer of one or more (meth)acrylic acid esters such as octyl ester and 2-ethylhexyl (meth)acrylate as monomers. In the base polymer, it is preferred to copolymerize polar monomers. Examples of polar monomers include: (meth)acrylic acid, (meth)acrylic acid 2-hydroxypropyl ester, (meth)acrylic acid hydroxyethyl ester, (meth)acrylamide, (meth)acrylic acid N, Monomers with carboxyl groups, hydroxyl groups, amide groups, amine groups, epoxy groups, etc., such as N-dimethylaminoethyl ester and glycidyl (meth)acrylate.

The adhesive composition may contain only the above-mentioned base polymer, but usually further contains a cross-linking agent. Examples of the cross-linking agent include metal ions having a valence of more than 2 and forming a carboxylic acid metal salt with the carboxyl group, polyamine compounds that form an amide bond with the carboxyl group, and polyamine compounds that form an ester bond with the carboxyl group. Polyepoxy compounds or polyols, and polyisocyanate compounds that form amide bonds with carboxyl groups. Among them, polyisocyanate compounds are preferred.

＜Method for manufacturing optical laminate＞ The present invention also relates to a method for manufacturing the optical laminate of the present invention. The manufacturing method of the optical laminate of the present invention includes the following steps: The retardation film preparation step is to prepare a laminated body including an optical anisotropic layer, an alignment layer, and a base film in this order (hereinafter, the laminated body is also referred to as a "retardation film"); The first laminating step involves laminating the transparent protective film and the polarizing element using a first adhesive; The second laminating step is to laminate the polarizing element and the optical anisotropic layer of the retardation film using a second adhesive; a peeling step, which is to peel and remove the base film, or the base film and the alignment layer from the laminate obtained in the second laminating step; and The adhesive layering step is to layer the adhesive layer on the area exposed by the peeling step.

The retardation film can be produced in the retardation film preparation step. In this case, the method of forming the alignment layer and the optically anisotropic layer on the base film is as described above.

The first adhesive used in the first laminating step is an adhesive that forms the first adhesive layer, and the details of the adhesive are as described above. The first adhesive is preferably an active energy ray-curable adhesive, more preferably a radical polymerizable active energy ray-curable adhesive, and further preferably contains a (meth)acrylic curing component and a radical polymerization initiator. Active energy ray hardening adhesive based on free radical polymerizability of the agent.

When the first adhesive is a dry-curable adhesive, after the transparent protective film and the polarizing element are bonded (laminated) via the first adhesive, the solvent in the first adhesive is removed from the obtained laminate. Allow to dry and remove, allowing to harden as appropriate. The drying process and/or the removal of the solvent can be performed, for example, by blowing hot air. The temperature depends on the type of solvent, but is usually 30°C or more and 200°C or less, preferably 35°C or more and 150°C or less, and more preferably 40°C. ℃ or more and 100°C or less, and more preferably 50°C or more and 100°C or less.

The drying and removal (optionally hardening) of the solvent in the first adhesive is preferably performed after performing the second bonding step of bonding (laminating) the polarizing element and the retardation film via the second adhesive. The solvent in the second adhesive is dried and removed (hardening if necessary) at the same time.

When the first adhesive is an active energy ray curable adhesive, the first adhesive is cured by irradiating active energy rays, thereby obtaining a first adhesive layer. The light source of the active energy ray is not particularly limited, but it is preferably an active energy ray with a luminescence distribution below a wavelength of 400 nm, and more preferably ultraviolet light. Specific examples of the light source include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

The light irradiation intensity of the active energy ray curing adhesive is appropriately determined according to the composition of the active energy ray curing adhesive and is not particularly limited. The irradiation intensity in the wavelength region effective for activation of the polymerization initiator is usually 10 mW/ ^cm2 or more and 3,000 mW/ ^cm2 or less. The light irradiation time of the active energy ray curing adhesive can be appropriately selected according to the active energy ray curing adhesive to be cured and is not particularly limited. It is usually 0.1 seconds to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and even more preferably 10 seconds to 1 minute. If irradiation with such ultraviolet irradiation intensity is performed once or multiple times, the cumulative light amount is usually from 10 mJ/ ^cm2 to 3,000 mJ/ ^cm2 , preferably from 50 mJ/ ^cm2 to 2,000 mJ/ ^cm2 , and more preferably from ¹⁰⁰ mJ/cm2 to 1,000 mJ/ ^cm2 .

The curing of the first adhesive by irradiation of active energy rays is preferably performed with the second adhesive after the second bonding step of bonding (laminating) the polarizing element and the retardation film through the second adhesive. The hardening is implemented together.

The second bonding step can be performed in the same manner as the first bonding step. In one embodiment, the first laminating step and the second laminating step are performed simultaneously. The second adhesive is an adhesive that forms the second adhesive layer, and the details of the adhesive are as described above. The second adhesive is preferably an active energy ray-curable adhesive, more preferably a radical polymerizable active energy ray-curable adhesive, and further preferably contains a (meth)acrylic curing component and a radical polymerization initiator. Active energy ray hardening adhesive based on free radical polymerizability of the agent. The first adhesive and the second adhesive may be different adhesives, but are preferably the same adhesive.

Through the first laminating step and the second laminating step, a laminated body having a layer structure of a transparent protective film/first adhesive/polarizing element/second adhesive/retardation film is obtained. Regarding this laminated body, before the peeling step, the solvents of the first adhesive and the second adhesive are dried and removed (curing as the case may be), or cured by irradiation of active energy rays.

When the first adhesive and the second adhesive are active energy ray curing adhesives, and the first adhesive and the second adhesive contained in the above-mentioned laminate are cured by irradiation with active energy rays, in one embodiment, the active energy rays are irradiated from the retardation film side. This embodiment is advantageous in that the first adhesive and the second adhesive can be sufficiently cured even when the transparent protective film contains an ultraviolet absorber or other ultraviolet absorbing ability.

Regarding the above-mentioned laminate in which the solvents of the first adhesive and the second adhesive have been dried and removed (cured as the case may be) or cured by irradiation with active energy rays, in the peeling step, the base film, Alternatively, the substrate film and the alignment layer are layered with an adhesive layer on the area exposed through the peeling step, thereby obtaining an optical laminate. When the base film is peeled off and removed in the peeling step, an optical laminate including the alignment layer 60 as shown in FIG. 1 is obtained. When the base film and the alignment layer are peeled off and removed in the peeling step, an optical laminate is obtained. The optical laminate without alignment layer 60 is shown in FIG. 2 .

Optical laminates can be continuously manufactured by the Roll to Roll method. For example, it can be continuously produced by the following method: making a retardation film rolled into a roll, transporting the retardation film while rolling it out, and using an adhesive for bonding each layer to the separately produced polarizing element and After the transparent protective film is sequentially laminated on the retardation film, the adhesive is dried or hardened, and then the base film, or the base film and the alignment layer are peeled off, and an adhesive layer is layered on the area exposed by peeling. Therefore, in one embodiment, the optical laminate may be in the form of a roll of optical laminate rolled into a roll.

In one embodiment, it is preferred that the optical laminate be laminated in such a manner that the angle between the slow axis (optical axis) of the optical anisotropic layer constituting the optical laminate and the absorption axis of the polarizing element is 45±5°.

<Image display device> The optical multilayer body of the present invention can be used in an image display device. The so-called image display device is a device having an image display element and including a light-emitting element or a light-emitting device as a light source. Examples of image display devices include: liquid crystal display devices, organic electroluminescent (EL) display devices, inorganic electroluminescent (EL) display devices, touch panel display devices, electron emission display devices (such as field emission display devices (FED), surface field emission display devices (SED)), electronic paper (display devices using electronic ink or electrophoretic elements), plasma display devices, projection display devices (such as grating valve imaging system (GLV) display devices, display devices with digital micromirror devices (DMD)) and piezoelectric ceramic displays. The liquid crystal display device may also be any one of a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, a reflective liquid crystal display device, a direct-view liquid crystal display device, and a projection liquid crystal display device. Such display devices may be display devices for displaying two-dimensional images, or may be stereoscopic display devices for displaying three-dimensional images. In particular, the optical multilayer of the present invention may be preferably used in organic electroluminescent (EL) display devices, inorganic electroluminescent (EL) display devices, liquid crystal display devices, and touch panel display devices.

The optical laminate of the present invention has excellent flexibility, so the image display device is preferably a flexible image display device. The flexible image display device preferably further has a window and a touch sensor.

The flexible image display device includes, for example, a flexible image display device laminate and an organic EL display panel. The flexible image display device laminate is disposed on the viewing side relative to the organic EL display panel and is configured in a bendable manner. The flexible image display device laminate may include a window, a touch sensor, etc. in addition to the optical laminate of the present invention. The order of lamination is arbitrary, and preferably, the window, the optical laminate, the touch sensor, or the window, the touch sensor, and the elliptical polarizer are laminated in sequence from the viewing side.

If there is an optical laminate on the visible side of the touch sensor, the pattern of the touch sensor is not easily visible, and the visibility of the displayed image is improved, which is preferred. Each component can be laminated using adhesives, adhesives, etc. In addition, the laminate for the flexible image display device can have a light-shielding pattern formed on at least one side of any one of the windows, optical laminates, and touch sensors.

The window is usually arranged on the viewing side of the flexible image display device, and is responsible for protecting other components from external impact or environmental changes such as temperature and humidity. The window includes a flexible transparent substrate and may also include a hard coating layer on at least one side. The window, touch sensor, etc. that constitute the multilayer body of the flexible image display device are not particularly limited, and previously known ones can be used. [Example]

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Unless otherwise specified, "%" and "parts" in the examples mean mass % and mass parts respectively.

<Example 1> [Preparation of a photo-alignment film-forming composition (X)] A photo-alignment material having the following structure (weight average molecular weight: 50,000, m:n=50:50) was prepared according to the method described in Japanese Patent Publication No. 2021-196514. 2 parts of the photo-alignment material were mixed with 98 parts of cyclopentanone (solvent), and the obtained mixture was stirred at 80°C for 1 hour to prepare a photo-alignment film-forming composition (X). Photo-alignment material: [Chemical 3]

[Preparation of polymerizable liquid crystal compound] A polymerizable liquid crystal compound (A1) and a polymerizable liquid crystal compound (A2) having the structures shown below were prepared respectively. The polymerizable liquid crystal compound (A1) was prepared in the same manner as described in Japanese Patent Publication No. 2019-003177. The polymerizable liquid crystal compound (A2) was prepared in the same manner as described in Japanese Patent Publication No. 2009-173893. Polymerizable liquid crystal compound (A1): [Chemical 4] Polymerizable liquid crystal compound (A2): [Chemical 5]

1 mg of the polymerizable liquid crystal compound (A1) was dissolved in 10 mL of chloroform to obtain a solution. The obtained solution was added to a measurement cell with an optical path length of 1 cm as a measurement sample, and the measurement sample was set in a UV-visible spectrophotometer ("UV-2450" manufactured by Shimadzu Corporation) for measurement. Absorption spectrum. The wavelength that became the maximum absorption was read from the obtained absorption spectrum. As a result, the maximum absorption wavelength λmax in the wavelength range of 300 to 400 nm was 356 nm.

[Preparation of liquid crystal cured film forming composition (Y)] The polymerizable liquid crystal compound (A1) and the polymerizable liquid crystal compound (A2) were mixed at a mass ratio of 90:10 to obtain a mixture. To 100 parts of the obtained mixture were added 0.1 part of a leveling agent "BYK-361N" (manufactured by BM Chemie Co., Ltd.) and 3 parts of "Irgacure OXE-03" (manufactured by BASF Japan Co., Ltd.) as a photopolymerization initiator. Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration became 13%. This mixture was stirred at a temperature of 80° C. for 1 hour, thereby preparing a liquid crystal cured film forming composition (Y). Table 1 shows the composition (excluding solvent) of the liquid crystal cured film forming composition (Y).

[Table 1] Polymerizable liquid crystal compound (A1) [parts] Polymerizable liquid crystal compound (A2) [parts] BYK-361N[unit] Irgacure OXE-03 [unit] 90 10 0.1 3

[Production of phase difference film (Z)] The above-mentioned photo alignment film forming composition (X) was coated on a biaxially stretched polyethylene terephthalate (PET) film (DIAFOIL manufactured by Mitsubishi Plastics Co., Ltd.) as a base film using a rod coater. ). The obtained coating film was dried at 120° C. for 2 minutes, and then cooled to room temperature to form a dry coating. Thereafter, a UV irradiation device (SPOT CURE SP-9; manufactured by Ushio Electric Co., Ltd.) was used to irradiate polarized ultraviolet light of 100 mJ (313 nm standard) to obtain a photo-alignment film D. The thickness of the optical alignment film D measured using an ellipsometer M-220 manufactured by Japan Spectroscopic Co., Ltd. was 200 nm.

The above composition for forming a liquid crystal cured film was coated on the obtained optical alignment film using a bar coater to form a coating film. The coating film was heated and dried at 120°C for 2 minutes, and then cooled to room temperature to obtain a dry coating. Then, a high-pressure mercury lamp ("Unicure VB-15201BY-A" manufactured by Ushio Electric Co., Ltd.) was used to irradiate the above-mentioned dry coating with ultraviolet light with an exposure dose of 500 mJ/cm ² (based on 365 nm) in a nitrogen atmosphere. Thereby forming an optically anisotropic layer in which the polymerizable liquid crystal compound is hardened in a state of being aligned in the horizontal direction with respect to the plane of the substrate, thereby obtaining a substrate film/photoalignment film/optically anisotropic layer (horizontally aligned liquid crystal Hardened film) retardation film (Z). The thickness of the optical anisotropic layer measured using a laser microscope LEXT OLS4100 manufactured by Olympus Co., Ltd. was 2.0 μm.

The liquid crystal side of the retardation film (Z) was subjected to corona treatment and adhered to glass using a 25 μm thick pressure-sensitive adhesive manufactured by LINTEC, and the PET film was peeled off. The in-plane retardation value was measured using KOBRA-WR manufactured by Oji Testing Instruments Co., Ltd. In-plane retardation values for light with wavelengths of 450 nm, 550 nm, and 650 nm were calculated using the Cauchy dispersion formula obtained from the results of the in-plane retardation values for light with wavelengths of 448.2 nm, 498.6 nm, 548.4 nm, 587.3 nm, 628.7 nm, and 748.6 nm. As a result, the in-plane phase difference values are Re(450) = 122 nm, Re(550) = 140 nm, and Re(650) = 144 nm. The relationship between the in-plane phase difference values at each wavelength is as follows. Re(450)/Re(550) = 0.87 Re(650)/Re(550) = 1.03 (In the formula, Re(450) represents the in-plane phase difference value for light with a wavelength of 450 nm, Re(550) represents the in-plane phase difference value for light with a wavelength of 550 nm, and Re(650) represents the in-plane phase difference value for light with a wavelength of 650 nm)

[Production of polarizing element] A 30 μm thick polyvinyl alcohol film (PVA: average degree of polymerization of about 2400, saponification degree of 99.9 mol% or more) was stretched uniaxially to about 5 times by dry stretching, and then immersed in pure water at 40°C for 40 seconds while maintaining the stretched state. Thereafter, the film was dyed by immersing in a dyeing aqueous solution with a mass ratio of iodine/potassium iodide/water of 0.044/5.7/100 at 28°C for 30 seconds. Subsequently, the film was immersed in a boric acid aqueous solution with a mass ratio of potassium iodide/boric acid/water of 11.0/6.2/100 at 70°C for 120 seconds. Then, after washing with pure water at 8°C for 15 seconds, it was dried at 60°C for 50 seconds while maintaining a tension of 300 N, and then dried at 75°C for 20 seconds to obtain a polarizing element with a thickness of 12 μm in which iodine was adsorbed and aligned on a polyvinyl alcohol film.

[Production of optical laminates] After the liquid crystal cured film side of the phase difference film is subjected to a corona treatment, the phase difference film (Z) produced above, the polarizing element, and the triacetyl cellulose film (TAC: "KC4UY" manufactured by Konica Minolta Opto (Co., Ltd.), thickness 40 μm) subjected to saponification treatment as a transparent protective film are sequentially laminated in such a manner that the liquid crystal cured film side of the phase difference film faces the polarizing element and the side opposite to the phase difference film of the polarizing element faces the transparent protective film. At this time, an aqueous dry curing adhesive is injected between the liquid crystal cured film and the polarizing element, and between the polarizing element and the transparent protective film. In addition, the absorption axis of the polarizing element and the slow axis of the liquid crystal cured film in the phase difference film are laminated in such a manner that they form an angle of 45°. The obtained laminate is passed through a roller to bond the layers. The obtained laminate is dried at 60°C for 2 minutes while the tension of the obtained laminate is maintained at 430 N/m. Thereafter, only the base film (PET film) of the phase difference film is peeled off, and the adhesive layer with the isolation film is applied to the exposed area by peeling, thereby obtaining an optical laminate (1) comprising an adhesive layer with isolation film/photo-alignment film/optical anisotropic layer (liquid crystal cured film)/adhesive layer/polarizing element/adhesive layer/transparent protective film. The thickness of the optical laminate (1) without the adhesive layer is 54 μm.

The above-mentioned water-based drying and curing adhesive is made by adding 3 parts of carboxyl-modified polyvinyl alcohol (KURARAY POVAL KL318; manufactured by Kuraray Co., Ltd.) and water-soluble polyamide epoxy resin (Sumirez Resin 650) to 100 parts of water; Manufactured by Sumika Chemtex Co., Ltd. and prepared with a solid content concentration of 30% aqueous solution) 1.5 parts.

[Evaluation of optical laminates] (1)Flexibility evaluation The flexibility was evaluated using a flexure testing machine ("CFT-720C" (trade name) manufactured by Covotech), and the optical laminate (1) was flexed so that the transparent protective film side became inside. . Place the adhesive layer side of the optical laminate (1) from which the isolation film has been peeled off in a flat state (undeflected state) and attach it to the sample stage of the flexure testing machine. When bending the optical laminated body (1), bend the optical laminated body 180° so that the distance between the opposing transparent protective films becomes 4.0 mm (bending radius R = 2 mm). Afterwards, it returned to its original flat state. When a series of operations is performed once, the number of bending operations is counted as one, and the bending operations are repeated. The deflection speed was set to 60 rpm. The number of deflections when cracks or bulges in the adhesive layer occur in the area deflected due to the bending operation is recorded as the limit number of deflections. The ultimate number of deflections is evaluated based on the following criteria. A: No cracks or bulges occurred even after more than 100,000 deflections. B: The number of deflections is more than 80,000 times and less than 100,000 times, resulting in cracks and bulges. C: The number of deflections is more than 50,000 times and less than 80,000 times, resulting in cracks and bulges. D: The number of deflections is more than 10,000 times and less than 50,000 times, resulting in cracks and bulges. E: The number of flexures does not reach 10,000 times, cracks and bulges occur.

(2) Evaluation of adhesion Before forming an adhesive layer on the photo-alignment film of the optical laminate (1), a sample piece was cut out from an arbitrary position, and the adhesion between the optical anisotropic layer and the polarizing element was evaluated according to the cross-cutting method of JIS K 5600. The specific evaluation criteria are as follows. The results are shown in Table 2. The adhesion between the optical anisotropic layer and the polarizing element of the optical laminate (1) is B. A: All lattices are not peeled off B: The coating is partially peeled off (more than 1% and less than 50%) C: The coating is completely peeled off (more than 50%)

<Example 2> An optical laminated body (2) was produced in the same manner as in Example 1, except that a corona-treated polymethyl methacrylate resin film (PMMA: manufactured by Sumitomo Chemical Co., Ltd., thickness 40 μm) was used as a transparent protective film. Make an assessment. The results are shown in Table 2.

<Example 3> Except that a corona-treated annular polyolefin resin film (COP: ZF-14 manufactured by Japan Zeon, thickness 40 μm) was used as the transparent protective film, an optical laminate (3) was prepared in the same manner as Example 1 and evaluated. The results are shown in Table 2.

<Example 4> An optical laminated body ( 4), conduct evaluation. The results are shown in Table 2.

<Example 5> After corona treatment is performed on the liquid crystal cured film side of the retardation film, the liquid crystal cured film side of the retardation film faces the polarizing element and the side opposite to the retardation film of the polarizing element faces the transparent protective film. , a retardation film (Z), a polarizing element, and a saponified triacetyl cellulose film (TAC: "KC4UY" manufactured by Konica Minolta Opto Co., Ltd.) as a transparent protective film are laminated in this order. At this time, a radically polymerizable ultraviolet curable adhesive is injected between the liquid crystal cured film and the polarizing element, and between the polarizing element and the transparent protective film. Furthermore, they are laminated so that the absorption axis of the polarizing element and the slow axis of the liquid crystal cured film in the retardation film form an angle of 45°. The obtained laminated body is passed through a nip roller, and each layer is bonded together. Ultraviolet light with an exposure dose of 1000 mJ was irradiated from the retardation film side of the obtained bonded product. Thereafter, only the base film (PET film) of the retardation film is peeled off, and an adhesive layer with an isolation film is laminated on the area exposed by the peeling to obtain an adhesive layer with an isolation film/optical alignment film/optical film. Optical laminate (5) of anisotropic layer (liquid crystal cured film)/adhesive layer/polarizing element/adhesive layer/transparent protective film. The thickness of the optical laminate (5) without the adhesive layer is 56 μm.

The above-mentioned radically polymerizable ultraviolet curable adhesive is an ultraviolet curable adhesive containing a (meth)acrylic curing component and a radical polymerization initiator, which is prepared by mixing the following components. Acrylamide (manufactured by Kohjin Co., Ltd.) 23.1 parts of isostearyl acrylate (manufactured by Osaka Organic Chemical Industry) 31.1 parts of Light acrylate LA: Lauryl acrylate (manufactured by Kyoei Chemical Co., Ltd.) 7.7 parts of PLACCEL FA1DDM: Unsaturated fatty acid Hydroxyalkyl ester modified ε-caprolactone (manufactured by Daicel) 23.1 parts Light acrylate 1,9NDA: 1,9-nonanediol diacrylate (manufactured by Kyei Chemical) 15.0 parts ARUFON-UP1190: Acrylic polymer ( Toa Gosei Co., Ltd.) 15.3 parts of IRGCURE.907: 2-methyl-1-(4-methylthiophenyl)-2-morpholinylpropan-1-one (manufactured by BASF) 3.5 parts of KAYACURE DETX-S: Diethyl Base 9-oxosulfide𠮿 (Manufactured by Nippon Kayaku) 3.5 parts

<Example 6> An optical laminate (6) was produced in the same manner as in Example 5, except that a corona-treated polymethyl methacrylate resin film (PMMA: manufactured by Sumitomo Chemical Co., Ltd., thickness 40 μm) was used as a transparent protective film. Make an assessment. The results are shown in Table 2.

<Example 7> An optical laminate (7) was produced in the same manner as in Example 5, except that a corona-treated cyclic polyolefin resin film (COP: ZF-14 manufactured by Nippon Zeon, thickness 40 μm) was used as a transparent protective film. Make an assessment. The results are shown in Table 2.

<Example 8> An optical laminated body ( 8), conduct evaluation. The results are shown in Table 2.

<Example 9> After corona treatment is performed on the liquid crystal cured film side of the retardation film, the liquid crystal cured film side of the retardation film faces the polarizing element and the side opposite to the retardation film of the polarizing element faces the transparent protective film. , a retardation film (Z), a polarizing element, and a saponified triacetyl cellulose film (TAC: "KC4UY" manufactured by Konica Minolta Opto Co., Ltd.) as a transparent protective film are laminated in this order. At this time, a cationically polymerizable ultraviolet curable adhesive is injected between the liquid crystal cured film and the polarizing element, and between the polarizing element and the transparent protective film. Furthermore, they are laminated so that the absorption axis of the polarizing element and the slow axis of the liquid crystal cured film in the retardation film form an angle of 45°. The obtained laminated body is passed through a nip roller, and each layer is bonded together. While maintaining the tension of the obtained bonded body at 430 N/m, ultraviolet light with an exposure dose of 1000 mJ was irradiated from the side of the optically anisotropic layer. Thereafter, only the base film (PET film) of the retardation film is peeled off, and an adhesive layer with an isolation film is laminated on the area exposed by the peeling to obtain an adhesive layer with an isolation film/optical alignment film/optical film. Optical laminate (9) of anisotropic layer (liquid crystal cured film)/adhesive layer/polarizing element/adhesive layer/transparent protective film. The thickness of the optical laminate (9) without the adhesive layer is 55 μm.

The above-mentioned cationic polymerizable ultraviolet curing adhesive is a ultraviolet curing adhesive containing an epoxy compound and a cationic polymerization initiator prepared by mixing the following components. (3,4-Epoxy) cyclohexylcarboxylic acid 3,4-epoxycyclohexyl methyl ester       40 parts Bisphenol A diglycidyl ether        60 parts Diphenyl (4-phenylthiophenyl) antimonium hexafluoroantimonate (photocationic polymerization initiator)        4 parts

<Example 10> Except that a polymethyl methacrylate resin film (PMMA: manufactured by Sumitomo Chemical Co., Ltd., thickness 40 μm) subjected to corona treatment was used as the transparent protective film, an optical laminate (10) was prepared in the same manner as Example 9 and evaluated. The results are shown in Table 2.

<Example 11> Except that a corona-treated annular polyolefin resin film (COP: ZF-14 manufactured by Japan Zeon, thickness 40 μm) was used as the transparent protective film, an optical laminate (11) was prepared in the same manner as Example 9 and evaluated. The results are shown in Table 2.

<Example 12> Except that a polyethylene terephthalate film (PET: DIAFOIL manufactured by Mitsubishi Resin Co., Ltd., thickness 38 μm) subjected to corona treatment was used as the transparent protective film, an optical laminate (12) was prepared in the same manner as Example 9 and evaluated. The results are shown in Table 2.

＜Comparative example 1＞ An adhesive layer with a separation film was laminated on the base film area of the laminated body produced according to Example 2 of Japanese Patent Application Laid-Open No. 2022-044293 to obtain an optical laminated body (13). The layer structure of the optical laminate (13) is an adhesive layer with a separation film/base film/photo alignment film/optically anisotropic layer (liquid crystal cured film)/adhesive layer/polarizing element/adhesive layer/transparent protection membrane.

<Comparative Example 2> An optically anisotropic layer (liquid crystal cured film) of a laminate prepared according to Example 1 of Japanese Patent Publication No. 2022-044293 is coated with an adhesive layer with a spacer film to obtain an optical laminate (14). The layer structure of the optical laminate (14) is an adhesive layer with a spacer film/optically anisotropic layer (liquid crystal cured film)/optical alignment film/base film/adhesive layer/polarizing element/adhesive layer/transparent protective film.

＜Comparative Example 3＞ An adhesive layer with a separation film was laminated on the base film area of the laminate produced according to Example 3 of Japanese Patent Application Laid-Open No. 2022-044293 to obtain an optical laminate (15). The layer structure of the optical laminate (15) is an adhesive layer with a separation film/base film/photo alignment film/optically anisotropic layer (liquid crystal cured film)/adhesive layer/polarizing element/adhesive layer/transparent protection membrane.

<Comparative Example 4> An optical laminate (16) is obtained by attaching an adhesive layer with a spacer film to the substrate film area layer of the laminate prepared according to Example 4 of Japanese Patent Publication No. 2022-044293. The layer structure of the optical laminate (16) is an adhesive layer with a spacer film/substrate film/optical alignment film/optical anisotropic layer (liquid crystal curing film)/adhesive layer/polarizing element/adhesive layer/transparent protective film.

<Comparative Example 5> An optical laminate (17) is obtained by attaching an adhesive layer with an isolation film to the optical alignment film area layer of the laminate prepared according to Comparative Example 1 of Japanese Patent Publication No. 2022-044293. The layer structure of the optical laminate (17) is an adhesive layer with an isolation film/optical alignment film/optical anisotropic layer (liquid crystal cured film)/adhesive layer/polarizing element/adhesive layer/transparent protective film.

[Table 2] Optical laminate 1st and 2nd adhesive layer Transparent protective film Thickness of optical laminate (excluding adhesive layer) Flexibility Assessment Adhesion assessment Embodiment 1 (1) Water-based adhesive TAC 54 A A Embodiment 2 (2) PMMA 54 A A Embodiment 3 (3) COP 54 B C Embodiment 4 (4) PET 52 B B Embodiment 5 (5) Free radical polymerizable UV curable adhesive TAC 56 A A Embodiment 6 (6) PMMA 56 A A Embodiment 7 (7) COP 56 B A Embodiment 8 (8) PET 54 B A Embodiment 9 (9) Cationic polymerizable UV curing plastic adhesive TAC 55 A B Embodiment 10 (10) PMMA 55 A B Embodiment 11 (11) COP 55 B B Embodiment 12 (12) PET 53 B B Comparison Example 1 (13) Water-based adhesive TAC 95 D A Comparison Example 2 (14) TAC 95 D A Comparison Example 3 (15) PMMA 95 D A Comparison Example 4 (16) COP 95 D C Comparison Example 5 (17) (Adhesive) TAC 59 E A

1: Optical laminate 2: Optical laminate 10: Transparent protective film 20: Polarizing element 30: Optical anisotropic layer 40: Adhesive layer 51: First adhesive layer 52: Second adhesive layer 60: Alignment layer

FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of an optical laminate. FIG. 2 is a schematic cross-sectional view showing another example of the layer structure of the optical laminate.

1: Optical laminated body

10:Transparent protective film

20: Polarizing element

30:Optical anisotropic layer

40:Adhesive layer

51: 1st adhesive layer

52: 2nd adhesive layer

60:Alignment layer

Claims (13)

An optical laminate including a transparent protective film, a first adhesive layer, a polarizing element, a second adhesive layer, an optically anisotropic layer, and an adhesive layer in this order, Only the first adhesive layer is interposed between the transparent protective film and the polarizing element, and only the second adhesive layer is interposed between the polarizing element and the optical anisotropic layer. The above-mentioned optically anisotropic layer-based liquid crystal cured film, The thickness of the above-mentioned optically anisotropic layer is 0.1 μm or more and 5 μm or less, and The optically anisotropic layer is directly connected to the adhesive layer, or an alignment layer is included between the optically anisotropic layer and the adhesive layer. The optical laminate according to claim 1, wherein the thickness of the first adhesive layer and the second adhesive layer is 50 nm or more and 2000 nm or less. The optical laminated body according to claim 1, wherein the first adhesive layer and the second adhesive layer are layers formed of a dry curable adhesive or an active energy ray curable adhesive. The optical laminate according to claim 1, wherein the optically anisotropic layer has reverse wavelength dispersion. The optical multilayer of claim 1, wherein the in-plane phase difference of the optical anisotropic layer to light of a wavelength of 550 nm is greater than 100 nm and less than 160 nm. An optical multilayer as claimed in claim 1, wherein the optical anisotropic layer has an optical axis that is oblique to the long direction of the polarizing element. The optical laminate of claim 1, wherein the alignment layer is a photo-alignment film comprising a photo-alignment polymer containing photo-reactive groups. The optical laminate according to claim 1 further includes an anti-reflection layer on the side of the transparent protective film opposite to the polarizing element. The optical laminate according to claim 1, wherein the polarizing element contains a polyvinyl alcohol-based resin film containing a dichroic dye. An image display device including the optical laminated body according to any one of claims 1 to 9. A method for manufacturing an optical laminate, which is a method for manufacturing an optical laminate as claimed in any one of claims 1 to 9, and comprises: A phase difference film preparation step, which is to prepare a phase difference film comprising an optical anisotropic layer, an alignment layer, and a substrate film in sequence; A first bonding step, which is to bond the transparent protective film to the polarizing element using a first bonding agent; A second bonding step, which is to bond the polarizing element to the optical anisotropic layer of the phase difference film using a second bonding agent; A peeling step, which is to peel off the substrate film, or the substrate film and the alignment layer, from the laminate obtained by the second bonding step; and The adhesive layer deposition step is to deposit the adhesive layer on the surface exposed by the stripping step. A method for manufacturing an optical laminate as claimed in claim 11, wherein the first adhesive and the second adhesive are active energy ray-curing adhesives. The method for manufacturing an optical laminate as claimed in claim 12 further includes the following step after the second bonding step and before the peeling step: irradiating the phase difference film side of the laminate obtained by the second bonding step with active energy rays to cure the first adhesive and the second adhesive.