WO2024038667A1

WO2024038667A1 - Optical laminated body and method for manufacturing same

Info

Publication number: WO2024038667A1
Application number: PCT/JP2023/021503
Authority: WO
Inventors: 敏幸上野; 伸行幡中
Original assignee: 住友化学株式会社
Priority date: 2022-08-19
Filing date: 2023-06-09
Publication date: 2024-02-22
Also published as: JP2024027813A

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 µm. 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 laminate and its manufacturing method

The present invention relates to an optical laminate and a method for manufacturing the same.

An elliptically polarizing plate is an optical member in which a polarizing plate and a retardation plate are laminated. For example, in an image display device such as an organic EL image display device, it is used to prevent light reflection at the electrodes constituting the device. It is used. As a retardation plate, a retardation plate using a cured liquid crystal film produced by applying a polymerizable liquid crystal compound onto a base material and curing it is known (Patent Document 1).

JP2022-044293A

In recent years, with the spread of bendable flexible displays, elliptically polarizing plates are also required to have greater flexibility. An object of the present invention is to provide an optical laminate having excellent flexibility.

The present invention provides the following optical laminate and method for manufacturing the same.
[1] An optical laminate comprising a transparent protective film, a first adhesive layer, a polarizer, 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 polarizer, and only the second adhesive layer is interposed between the polarizer and the optically anisotropic layer,
The optically anisotropic layer is a liquid crystal cured film,
The thickness of the optically anisotropic layer is 0.1 μm or more and 5 μm or less,
The optical laminate, wherein the optically anisotropic layer and the adhesive layer are in direct contact with each other, or an alignment layer is provided between the optically anisotropic layer and the adhesive layer.
[2] The optical laminate according to [1], wherein the first adhesive layer and the second adhesive layer have a thickness of 50 nm or more and 2000 nm or less.
[3] The optical device according to [1] or [2], wherein the first adhesive layer and the second adhesive layer are layers formed from a dry solidifying adhesive or an active energy ray curable adhesive. laminate.
[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 optically anisotropic layer has an in-plane retardation value of 100 nm or more and 160 nm or less for light with a wavelength of 550 nm.
[6] The optical laminate according to any one of [1] to [5], wherein the optically anisotropic layer has an optical axis oblique to the longitudinal direction of the polarizer.
[7] The optical laminate according to any one of [1] to [6], wherein the alignment layer is a photoalignment film made of a photoalignable polymer containing a photoreactive group.
[8] The optical laminate according to any one of [1] to [7], further comprising an antireflection layer on the opposite side of the transparent protective film from the polarizer.
[9] The optical laminate according to any one of [1] to [8], wherein the polarizer is composed of a polyvinyl alcohol resin film containing a dichroic dye.
[10] An image display device comprising the optical laminate according to any one of [1] to [9].
[11] A method for producing an optical laminate according to any one of [1] to [9], comprising:
a retardation film preparation step of preparing a retardation film including an optically anisotropic layer, an alignment layer, and a base film in this order;
a first bonding step of bonding the transparent protective film and the polarizer using a first adhesive;
a second bonding step of bonding the polarizer and the optically 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 bonding step;
an adhesive layer lamination step of laminating the adhesive layer on the surface exposed by the peeling step;
A method for producing an optical laminate, comprising:
[12] The method for producing an optical laminate according to [11], wherein the first adhesive and the second adhesive are active energy ray-curable adhesives.
[13] After the second bonding step and before the peeling step, active energy rays are irradiated from the retardation film side of the laminate obtained in the second bonding step to remove the first The method for producing an optical laminate according to [12], further comprising a step of curing the adhesive and the second adhesive.

An optical laminate with excellent flexibility can be provided.

It is a schematic sectional view showing an example of the layer composition of an optical layered product. FIG. 3 is a schematic cross-sectional view showing another example of the layer structure of the optical laminate.

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 drawings below are shown to help understand the present invention, and the size and shape of each component shown in the drawings do not necessarily correspond to the size and shape of the actual component.

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

The optical laminate 2 shown in FIG. 2 has the same layer structure as the optical laminate 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 with each other.

As in the example shown in FIGS. 1 and 2, the optical laminate includes a base material used when forming the optically anisotropic layer 30 between the polarizer 20 and the optically anisotropic layer 30. It does not have a material film (usually a thermoplastic resin film), and an adhesive layer (first adhesive layer 51) is used to bond the transparent protective film 10 and the polarizer 20. An adhesive layer (second adhesive layer 52) is used for bonding with the orientation layer 30. Since the optical laminate according to the present invention has such a configuration, it has excellent flexibility, and even if it is repeatedly bent, problems such as peeling and cracking are unlikely to occur at the bent portion. 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 optically anisotropic layer 30 and the adhesive layer 40.

The optical laminate includes a transparent protective film 10, a first adhesive layer 51, a polarizer 20, a second adhesive layer 52, an optically anisotropic layer 30, an alignment layer 60, and layers other than the adhesive layer 40 (e.g. , other layers having various functions that can be incorporated into image display devices, etc.). However, from the viewpoint of improving the flexibility of the optical laminate, other layers are not arranged between the transparent protective film 10 and the polarizer 20 and between the polarizer 20 and the optically anisotropic layer 30. First, preferably, it is not disposed between the optically anisotropic layer 30 and the adhesive layer 40 either.

The optical laminate can be suitably used as, for example, an elliptically polarizing plate. The term "elliptically polarizer" includes circularly polarizers.

Elements that constitute or can constitute the optical laminate will be described in detail below.
(2) Transparent Protective Film The optical laminate includes a transparent protective film 10 that is laminated on the opposite side of the polarizer 20 to the optically anisotropic layer 30. Since the polarizer 20 has a thin film thickness and its surface is easily damaged, protective films are usually provided on both sides of the polarizer 20 to prevent external damage and dirt. In the optical laminate, a transparent protective film is not laminated on the surface of the polarizer 20 on the optically anisotropic layer 30 side. This makes it possible to obtain an optical laminate that is thinner and has a lower diagonal reflectance.

The transparent protective film 10 preferably has a total light transmittance of 90% or more, more preferably 92% or more. When the total light transmittance is at least the above 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, and may be 100% or less. The total light transmittance can be measured, for example, according to JIS K 7361.

The transmittance of the transparent protective film 10 at a wavelength of 380 nm is preferably 30% or less, more preferably 25% or less, even more preferably 20% or less. If the transmittance is below the above upper limit value, when the optical laminate including the transparent protective film 10 is incorporated into an image display device, the layers constituting the interior of the optical laminate (polarized light 20, optically anisotropic layer 30, etc.). The lower limit of the transmittance of the transparent protective film 10 at a wavelength of 380 nm is not particularly limited, and may be 0%. In order to make the transmittance of the transparent protective film 10 30% or less at a wavelength of 380 nm, the transparent protective film 10 may contain an ultraviolet absorber or the like. Transmittance at a wavelength of 380 nm can be measured using a spectrophotometer, for example.

A thermoplastic resin film can be used as the transparent protective film 10. Examples of thermoplastic resins that can constitute the transparent protective film include cellulose resins such as triacetylcellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone resins; polysulfone resins; polycarbonate resins; nylon and aromatic polyamides. polyamide resins such as; polyimide resins; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin resins having cyclo and norbornene structures (also referred to as norbornene resins); (meth)acrylic resins; polyarylate resins ; polystyrene resin; polyvinyl alcohol resin, and mixtures thereof. In this specification, "(meth)acrylic" means either acrylic or methacryl. "(Meta)" in (meth)acrylate, (meth)acryloyl, etc. has the same meaning. Such a resin can be formed into a film by known means such as a solvent casting method and a melt extrusion method. The surface of the transparent protective film may be subjected to a surface treatment such as a release treatment such as a silicone treatment, a corona treatment, a plasma treatment, or the like.

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 preferably has a moisture permeability of 100 g/m ² /24 hours or more, more preferably 150 g/m ² /24 hours or more, and still more preferably 200 g/m ² /24 hours or more. When the moisture permeability of the transparent protective film 10 is equal to or higher than the above lower limit value, when forming an optical laminate by laminating the optically anisotropic layer 30 and the polarizer 20 using a dry-setting adhesive, the transparent protective film 10 is The solvent in the dry-setting adhesive can be efficiently removed from the film 10. This can shorten the time for removing the solvent in the dry-setting adhesive, which can 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.

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 and 150 μm or less, from the viewpoint of thinning the optical laminate, workability, flexibility, strength, etc. It is.

The transparent protective film 10 can include a surface treatment layer laminated on the surface opposite to the polarizer 20. Examples of the surface treatment layer include a hard coat layer and an antireflection layer. The hard coat layer is intended to prevent scratches on the surface, and includes, for example, a cured film made of ultraviolet curable resin such as (meth)acrylic and silicone. The antireflection layer is intended to prevent reflection of external light on the surface, and may be a conventionally known antireflection film or the like.

(3) Polarizer A polarizer is a film that has a function of extracting linearly polarized light from incident natural light, and is preferably a polyvinyl alcohol resin film containing a dichroic dye. As the polyvinyl alcohol resin constituting the polyvinyl alcohol resin film, saponified polyvinyl acetate resin can be used. Examples of polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers that can be copolymerized with vinyl acetate (for example, ethylene-vinyl acetate copolymer). combination, etc.). Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

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

A film formed from the above polyvinyl alcohol resin is used as the original film of the polarizer. The method of forming a polyvinyl alcohol resin into a film is not particularly limited, and any known method can be used to form the film. The thickness of the polyvinyl alcohol base film can be, for example, 10 μm or more and 150 μm or less.

Polarizers are usually produced through a process of uniaxially stretching the polyvinyl alcohol resin film, a process of dyeing the polyvinyl alcohol resin film with a dichroic dye, and a process of adsorbing the dichroic dye. It is manufactured through the steps of treating a polyvinyl alcohol-based resin film with a boric acid aqueous solution, and washing with water after the treatment with the boric acid aqueous solution. Note that by dyeing the polyvinyl alcohol resin film with a dichroic dye, the dichroic dye will be included in the polyvinyl alcohol resin film. When manufacturing a polarizer using such a manufacturing method, the polarizer is a stretched polyvinyl alcohol resin film containing a dichroic dye.

The uniaxial stretching of the polyvinyl alcohol resin film may be performed before dyeing with the dichroic dye, simultaneously with the dyeing, or after the dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during the boric acid treatment. It is also possible to perform uniaxial stretching in these multiple steps. In the uniaxial stretching, it may be uniaxially stretched between rolls having different circumferential speeds, or it may be uniaxially stretched using hot rolls. Further, the uniaxial stretching may be dry stretching in which the film is stretched in the atmosphere, or wet stretching in which the polyvinyl alcohol resin film is stretched in a swollen state using a solvent. From the viewpoint of suppressing deformation of the polarizer, the stretching ratio is preferably 8 times or less, more preferably 7.5 times or less, and even more preferably 7 times or less. Further, the stretching ratio is usually 4.5 times or more from the viewpoint of exhibiting the function as a polarizer. By setting the stretching ratio within the above range, deformation of the polarizer over time can be suppressed.

An example of a method for dyeing a polyvinyl alcohol resin film with a dichroic dye is a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing a dichroic dye. As the dichroic dye, for example, iodine or a dichroic dye is used. Examples of dichroic dyes include C.I. I. Dichroic direct dyes made of disazo compounds such as DIRECT RED 39, dichroic direct dyes made of trisazo, tetrakisazo compounds, etc. are included. In addition, it is preferable that the polyvinyl alcohol resin film is subjected to a water immersion treatment before the dyeing treatment.

When using iodine as a dichroic dye, a method is usually employed in which a polyvinyl alcohol resin film is immersed in an aqueous solution containing iodine and potassium iodide for dyeing. The content of iodine in this aqueous solution is usually about 0.01 part by mass or more and about 1 part by mass or less per 100 parts by mass of water. Further, the content of potassium iodide is usually about 0.5 parts by mass or more and about 20 parts by mass or less per 100 parts by mass of water. The temperature of the aqueous solution used for dyeing is usually about 20°C or more and about 40°C or less. Further, the immersion time (staining time) in this aqueous solution is usually 20 seconds or more and about 1,800 seconds or less.
Note that before the polyvinyl alcohol resin film is immersed in an aqueous solution containing iodine and potassium iodide, the film may be immersed in water in order to swell it and facilitate dyeing. The temperature of such immersion treatment is usually 20°C or more and 80°C or less, preferably 30°C or more and 60°C or less, and the immersion time (dying time) is usually 20 seconds or more and 1,800 seconds or less.

On the other hand, when using a dichroic organic dye as the dichroic dye, a method of dyeing by immersing a polyvinyl alcohol resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic organic dye in this aqueous solution is usually 1 x 10 ^-4 parts by mass or more and 10 parts by mass or less, preferably 1 x 10 ^-3 parts by mass or more and 1 part by mass or less, per 100 parts by mass of water. The amount is more preferably 1×10 ⁻³ parts by mass or more and 1×10 ⁻² parts by mass or less. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the dichroic dye aqueous solution used for dyeing is usually about 20°C or more and about 80°C or less. Further, the immersion time (staining time) in this aqueous solution is usually 10 seconds or more and about 1,800 seconds or less.

The boric acid treatment after dyeing with a dichroic dye can usually be carried out by immersing the dyed polyvinyl alcohol resin film in an aqueous boric acid solution. The content of boric acid in this boric acid aqueous solution is usually about 2 parts by mass or more and 15 parts by mass or less, preferably 5 parts by mass or more and 12 parts by mass or less, per 100 parts by mass of water. When iodine is used as the dichroic dye, the boric acid aqueous solution preferably contains potassium iodide, and the content of potassium iodide in this case is usually 0.1 mass parts per 100 mass parts of water. The amount is about 15 parts by mass or more, and preferably 5 parts by mass or more and 12 parts by mass or less. The immersion time in the boric acid aqueous solution is usually 60 seconds or more and about 1,200 seconds or less, preferably 150 seconds or more and 600 seconds or less, and more preferably 200 seconds or more and 400 seconds or less. The temperature of the boric acid treatment is usually 50°C or higher, preferably 50°C or higher and 85°C or lower, and more preferably 60°C or higher and 80°C or lower.

After the boric acid treatment, the polyvinyl alcohol resin film is usually washed with water. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of the water in the water washing process is usually about 5°C or more and about 40°C or less. Further, the immersion time is usually 1 second or more and about 120 seconds or less.

After washing with water, a drying process is performed to obtain the polarizer 20. The drying process can be performed using, for example, a hot air dryer or a far-infrared heater. The temperature of the drying treatment is usually 30°C or more and about 100°C or less, preferably 50°C or more and 80°C or less. The drying treatment time is usually about 60 seconds or more and about 600 seconds or less, preferably 120 seconds or more and about 600 seconds or less. The drying process reduces the moisture content of the polarizer to a practical level. The moisture content is usually about 5% by mass or more and about 20% by mass or less, preferably 8% by mass or more and about 15% by mass or less. When the moisture content is within the above range, it is easy to obtain a polarizer that has appropriate flexibility and excellent thermal stability.

The thickness of the polarizer 20 is preferably 5 μm or more and 40 μm or less, more preferably 5 μm or more and 20 μm or less.

(4) Optically anisotropic layer and alignment layer The optically anisotropic layer 30 is formed by coating a composition containing a polymerizable liquid crystal compound (hereinafter also referred to as "composition for forming a liquid crystal cured film") on a transparent base material. However, it is an optically anisotropic layer (hereinafter also referred to as "cured liquid crystal film") made of an oriented polymer of a polymerizable liquid crystal compound. Since the optically anisotropic layer 30 is a cured liquid crystal film, it is possible to reduce the thickness of the optically anisotropic layer 30 and to arbitrarily design the wavelength dispersion characteristics. Furthermore, the composition for forming a liquid crystal cured film may further contain a solvent, a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, a leveling agent, an adhesion improver, and the like.

A cured liquid crystal film is usually formed by coating a composition for forming a cured liquid crystal film on an alignment layer formed on a base material, and polymerizing the polymerizable liquid crystal compound contained in the composition for forming a cured liquid crystal film. formed by A liquid crystal cured film is usually a film that is cured with a polymerizable liquid crystal compound oriented.In order to generate a phase difference within the viewing plane, the polymerizable liquid crystal compound must be oriented horizontally with respect to the substrate surface. It is necessary that the film be a cured film in which the polymerizable groups are polymerized under the conditions. At this time, if the polymerizable liquid crystal compound is a rod-shaped liquid crystal, a positive A plate may be used, and if the polymerizable liquid crystal compound is a disk-shaped liquid crystal, a negative A plate may be used.

The liquid crystal cured film may be a λ/4 layer, a λ/2 layer, or a positive C layer. The optically anisotropic layer 30 may include two or more layers of liquid crystal cured films. Examples of the combination of two or more layers of liquid crystal cured films 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 viewpoint of achieving a high degree of antireflection function, it is sufficient to have a λ/4 plate function (that is, a π/2 phase difference function) in the entire visible light range. Specifically, a reverse wavelength dispersion λ/4 layer is preferable, and a combination of a positive wavelength dispersion λ/2 layer and a positive wavelength dispersion λ/4 layer may be used. Furthermore, from the viewpoint of compensating for the antireflection function in the oblique direction, it is preferable to further include a layer having anisotropy in the thickness direction (positive C plate). Further, each optically anisotropic layer may have a tilt orientation or may form a cholesteric orientation state. When the optically anisotropic layer 30 includes two or more liquid crystal cured films, the optically anisotropic layer 30 includes a bonding layer (adhesive layer or adhesive layer) for bonding these liquid crystal cured films to each other. May contain.

In the optically anisotropic layer 30, Re(λ), which is an in-plane retardation value for light with a wavelength of λ nm, preferably satisfies the following formula (1), the following formula (1), the following formula (2), and the following formula (1). It is more preferable that formula (3) is further satisfied.
100nm≦Re(550)≦160nm...(1)
(In the formula, Re(550) represents the in-plane retardation value (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) is the in-plane retardation value for light with a wavelength of 450 nm, Re (550) is the in-plane retardation value for light with a wavelength of 550 nm, and Re (650) is the in-plane retardation value for light with a wavelength of 650 nm. (Represents the phase difference value.)

When the optically anisotropic layer 30 satisfies the formula (1), when an optical laminate (elliptically polarizing plate) including the optically anisotropic layer 30 is applied to an image display device such as an organic EL display device, black display will occur. The front reflection hue is easily improved. Re(550) of the optically anisotropic layer 30 is more preferably 130 nm or more and 150 nm or less.

The optically anisotropic layer 30 preferably has reverse wavelength dispersion, and specifically preferably satisfies formulas (2) and (3). When the value of "Re(450)/Re(550)" of the optically anisotropic layer 30 exceeds 1.0, light leakage on the short wavelength side in the elliptically polarizing plate including the optically anisotropic layer becomes large. Become. 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, and even more 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, the stacking angle of the plurality of cured liquid crystal films, and the retardation value.

The in-plane retardation value Re(λ) of the optically anisotropic layer 30 can be adjusted by adjusting the thickness of the optically anisotropic layer 30. Since the in-plane retardation value Re(λ) is determined by the following formula (4), in order to obtain the desired in-plane retardation value Re(λ), Δn(λ) and the film thickness d must be adjusted. Bye. The thickness of the optically anisotropic layer 30 can be measured using an interference thickness meter, a laser microscope, or a stylus thickness meter. Note that Δn(λ) depends on the molecular structure of the polymerizable liquid crystal compound described later.
Re(λ)=d×Δn(λ)...(4)
(In the formula, Re(λ) represents the in-plane retardation value at the wavelength λnm, d represents the film thickness, and Δn(λ) represents the birefringence at the wavelength λnm.)

In addition, the positive C layer has a retardation value Rth (550 nm) in the thickness direction at a wavelength of 550 nm.
) is usually in the range of -170 nm or more and -10 nm or less, preferably -150 nm or more and -20 nm or less, and more preferably -100 nm or more and -40 nm. If the retardation value in the thickness direction is within this range, the antireflection properties from oblique directions can be further improved.

The polymerizable liquid crystal compound means a liquid crystal compound having a polymerizable group, particularly a photopolymerizable group, and as the polymerizable liquid crystal compound, it is possible to use a conventionally known polymerizable liquid crystal compound in the field of retardation films, for example. can. The photopolymerizable group refers to a group that can participate in a polymerization reaction by reactive species generated from a photopolymerization initiator, such as active radicals and acids. Examples of the photopolymerizable group include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, and the like. Among these, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable. The liquid crystal may be thermotropic liquid crystal or lyotropic liquid crystal, but thermotropic liquid crystal is preferable because it allows precise control of the film thickness. Further, the phase ordered structure of the thermotropic liquid crystal may be either a nematic liquid crystal or a smectic liquid crystal. Further, it may be a rod-shaped liquid crystal or a disc-shaped liquid crystal. The polymerizable liquid crystal compounds can be used alone or in combination of two or more.

From the viewpoint of exhibiting reverse wavelength dispersion, the polymerizable liquid crystal compound is preferably a liquid crystal having a T-shaped or H-shaped mesogenic structure that has further birefringence in the direction perpendicular to the long axis direction of the molecules, and has stronger dispersion. A T-shaped liquid crystal is more preferable from the viewpoint of obtaining the following. Specifically, the structure of the T-shaped liquid crystal is, for example, the following formula (I):

Examples include compounds represented by:

In formula (I), Ar represents a divalent aromatic group which may have a substituent. Preferably, the divalent aromatic group 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 are bonded to each other through a single bond or a divalent bonding group such as -CO-O- or -O-. You can leave it there.
G ¹ and G ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group is a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, or a fluoroalkyl group having 1 to 4 carbon atoms. It may be substituted with 1 to 4 alkoxy groups, cyano groups, or nitro groups, and the carbon atoms constituting the divalent aromatic group or divalent alicyclic hydrocarbon group are oxygen atoms, sulfur atoms. Alternatively, it may be substituted with 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 each independently represent an integer from 0 to 3, and satisfy the relationship 1≦k+l. Here, when 2≦k+l, B ¹ and B ² and G ¹ and G ² may be the same or different from each other.
E ¹ and E ² each independently represent an alkanediyl group having 1 to 17 carbon atoms, where the hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and the alkanediyl group The -CH ₂ - contained therein may be substituted with -O-, -S-, or -COO-, and when a plurality of -O-, -S-, or -COO- are present, they are not adjacent to each other. P ¹ and P ² each independently represent a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

G ¹ and G ² are each independently preferably a 1,4-phenylenediyl group optionally 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. , a 1,4-cyclohexanediyl group optionally 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, and more preferably a 1,4-cyclohexanediyl group substituted with a methyl group. ,4-phenylenediyl group, unsubstituted 1,4-phenylenediyl group, or unsubstituted 1,4-trans-cyclohexanediyl group, particularly preferably unsubstituted 1,4-phenylenediyl group or unsubstituted It is a substituted 1,4-trans-cyclohexanediyl group.
Furthermore, at least one of the plurality of G ¹ and G ² is preferably a divalent alicyclic hydrocarbon group, and at least one of G ¹ and G ² bonded to L ¹ or L ² More preferably, one is a divalent alicyclic hydrocarbon group.

L ¹ and L ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a1 OR ^a2 -, -R ^a3 COOR ^a4 -, -R ^a5 OCOR ^a6 -, R ^a7 OC=OOR ^a8 -, -N=N-, -CR ^c =CR ^d -, or -C≡C-. Here, R ^a1 to R ^a8 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms, and R ^c and R ^d represent an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. L ¹ and L ² are each independently more preferably a single bond, -OR ^a2-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a4-1 -, or -OCOR ^a6-1 - be. Here, R ^a2-1 , R ^a4-1 , and R ^a6-1 each independently represent a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. L ¹ and L ² are each independently more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, or -OCO-.

B ¹ and B ² 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 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms. B ¹ and B ² are each independently more preferably a single bond, -OR ^a10-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a12-1 -, or -OCOR ^a14-1 - be. Here, R ^a10-1 , R ^a12-1 , and R ^a14-1 each independently represent a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. B ¹ and B ² are each independently, more preferably, a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, -OCO-, or -OCOCH ₂ CH ₂ - be.

From the viewpoint of expressing reverse wavelength dispersion, k and l preferably satisfy 2≦k+l≦6, more preferably k+l=4, and even more preferably k=2 and l=2. It is preferable that k=2 and l=2 because a symmetrical structure is obtained.

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 P ¹ or P ² include epoxy group, vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, and oxiranyl group. , and oxetanyl group. Among these, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable.

It is preferable that Ar has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle which 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, with benzene rings and naphthalene rings being preferred. The aromatic heterocycles include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, and a pyrazole ring. , thiazole ring, benzothiazole ring, thienothiazole ring, oxazole ring, benzoxazole ring, and phenanthroline ring. Among these, it is preferable to have a thiazole ring, benzothiazole ring, or benzofuran ring, and more preferably to have a benzothiazole group. Further, when Ar includes 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, and even more preferably 14 or more. , particularly preferably 16 or more. Further, the total number Nπ is preferably 30 or less, more preferably 26 or less, and still more preferably 24 or less.

Preferred examples of the aromatic group represented by Ar include the following groups.

In formulas (Ar-1) to (Ar-23), the mark * represents a connecting part, and Z ⁰ , Z ¹ and Z ² each independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 12 carbon atoms. group, cyano group, nitro group, alkylsulfinyl group having 1 to 12 carbon atoms, alkylsulfonyl group having 1 to 12 carbon atoms, carboxyl group, fluoroalkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N,N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 12 carbon atoms, or Represents an N,N-dialkylsulfamoyl 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 optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group.

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 of 0 to 6.

Examples of the aromatic hydrocarbon group for Y ¹ , Y ² and Y ³ include aromatic hydrocarbon groups having 6 to 20 carbon atoms such as phenyl group, naphthyl group, anthryl group, phenanthryl group, and biphenyl group. , naphthyl group is preferred, and phenyl group is more preferred. Examples of the aromatic heterocyclic group include a group having 4 to 20 carbon atoms and containing at least one heteroatom such as a nitrogen atom, an oxygen atom, or a sulfur atom, such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group. Examples include aromatic heterocyclic groups, and furyl, thienyl, pyridinyl, thiazolyl, and benzothiazolyl groups are preferred.

Y ¹ , Y ² and Y ³ may each independently be an optionally substituted polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a fused polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group refers to a fused polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

Z ⁰ , Z ¹ and Z ² are each independently preferably 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; ⁰ is more preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a cyano group, and Z ¹ and Z ² are more preferably 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' -, -O-, and R ^2' is preferably a hydrogen atom. Among them, -S-, -O-, and -NH- are particularly preferred.

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

In formulas (Ar-16) to (Ar-23), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ⁰ . Examples of the aromatic heterocyclic group include those mentioned above as aromatic heterocycles that Ar may have, such as a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, and an indole ring. ring, quinoline ring, isoquinoline ring, purine ring, pyrrolidine ring, etc. This aromatic heterocyclic group may have a substituent. Further, Y ¹ may be the aforementioned 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 include a benzofuran ring, a benzothiazole ring, a benzoxazole ring, and the like.

Among polymerizable liquid crystal compounds, compounds with a maximum absorption wavelength of 300 nm or more and 400 nm or less are preferred. When the composition for forming a liquid crystal cured film contains a photopolymerization initiator, there is a possibility that the polymerization reaction and gelation of the polymerizable liquid crystal compound will proceed during long-term storage. However, if the maximum absorption wavelength of the polymerizable liquid crystal compound is 300 nm or more and 400 nm or less, even if exposed to ultraviolet light during storage, the generation of reactive species from the photopolymerization initiator and the polymerizable liquid crystal compound due to the reactive species The progress of polymerization reaction and gelation can be effectively suppressed. Therefore, it is advantageous in terms of long-term stability of the composition for forming a cured liquid crystal film, and the orientation and uniformity of the film thickness of the obtained cured liquid crystal film can be improved. Note that 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 includes, for example, 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, based on 100 parts by mass of the solid content of the composition for forming a liquid crystal cured film, and is preferably is 80 parts by mass or more and 99 parts by mass or less, more preferably 85 parts by mass or more and 98 parts by mass or less, still more preferably 90 parts by mass or more and 95 parts by mass or less. If the content of the polymerizable liquid crystal compound is within the above range, it is advantageous from the viewpoint of orientation of the optically anisotropic layer obtained. In addition, in this specification, the solid content of the composition for forming a liquid crystal cured film means all the components excluding volatile components such as organic solvents from the composition for forming the liquid crystal cured film.

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

The composition for forming a liquid crystal cured film is usually applied to a base film or the like in a state dissolved in a solvent, so it preferably contains a solvent. Generally, a polymerizable liquid crystal compound has a high viscosity, so a composition for forming a liquid crystal cured film dissolved in a solvent facilitates coating, and as a result, it often becomes easier to form an optically anisotropic layer. The solvent is preferably one that can completely dissolve the polymerizable liquid crystal compound, and is also preferably a solvent that is inert to the polymerization reaction of the polymerizable liquid crystal compound. Further, it is preferable that the solvent is a solvent that does not dissolve the base film used. Examples of solvents include alcohols such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy-2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether. Solvents: 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, etc. Ketone solvents; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; cycloaliphatic hydrocarbon solvents such as ethylcyclohexane; aromatic hydrocarbon solvents such as toluene, xylene and anisole; nitrile solvents such as acetonitrile; tetrahydrofuran and dimethoxyethane Ether solvents such as; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone (NMP), and 1,3-dimethyl-2-imidazolidinone. It will be done. These solvents can be used alone or in combination. Among these, from the viewpoint of film coating, it is preferable to use at least one selected from alcohol solvents, ester solvents, ketone solvents, chlorine-containing solvents, amide solvents, and aromatic hydrocarbon solvents, and the solubility of the polymerizable liquid crystal compound From this viewpoint, it is more preferable to use at least one selected from ester solvents, ketone solvents, amide solvents, and aromatic hydrocarbon solvents.

The content of the solvent in the composition for forming a liquid crystal cured film is preferably 50 parts by mass or more and 98 parts by mass or less, more preferably 70 parts by mass or more and 95 parts by mass or less, based on 100 parts by mass of the polymerizable liquid crystal composition. be. Therefore, the solid content in 100 parts by mass of the composition for forming a liquid crystal cured film is preferably 2 parts by mass or more and 50 parts by mass or less, more preferably 5 to 30 parts by mass. When the solid content is 50 parts by mass or less, the viscosity of the composition for forming a liquid crystal cured film becomes low, so that the thickness of the film tends to be substantially uniform and unevenness is less likely to occur. The solid content can be determined as appropriate in consideration of the thickness of the cured liquid crystal film to be produced.

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

As the photopolymerization initiator, any known photopolymerization initiator can be used as long as it is a compound that can initiate the polymerization reaction of the polymerizable liquid crystal compound. Specifically, photopolymerization initiators that can generate active radicals or acids by the action of light can be mentioned, and among them, photopolymerization initiators that can generate radicals by the action of light are preferred. The photopolymerization initiators 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 a photopolymerization initiator that generates active radicals, self-cleavable benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-Aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, azo compounds, etc. can be used, and hydrogen abstraction type benzophenone compounds, alkylphenone compounds, benzoin ether compounds, benzyl ketal compounds, dibenzo Suberone-based compounds, anthraquinone-based compounds, xanthone-based compounds, thioxanthone-based compounds, halogenoacetophenone-based compounds, dialkoxyacetophenone-based compounds, halogenobisimidazole-based compounds, halogenotriazine-based compounds, triazine-based compounds, etc. can be used. As the photopolymerization initiator that generates acid, iodonium salts, sulfonium salts, etc. can be used. From the viewpoint of excellent reaction efficiency at low temperatures, self-cleavable photopolymerization initiators are preferred, and acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, and oxime ester compounds are particularly preferred.

The photopolymerization initiator contained in the composition for forming a liquid crystal cured film is at least one type, and multiple types may be used in combination. You can select it as appropriate.

The content of the polymerization initiator in the composition for forming a liquid crystal cured film can be adjusted as appropriate depending on the type and amount of the polymerizable liquid crystal compound, but it is usually 0 parts by mass based on 100 parts by mass of the polymerizable liquid crystal compound. .1 parts by mass or more and 30 parts by mass 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. When the content of the polymerization initiator is within the above range, polymerization can be carried out without disturbing the orientation of the polymerizable liquid crystal compound.

The leveling agent is an additive that has the function of adjusting the fluidity of the composition for forming a liquid crystal cured film and making the coating film obtained by applying the composition for forming a liquid crystal cured film more flat. Alternatively, a polymer component containing a silicon atom or a polyacrylate-based polymer is preferable, and a surfactant whose main component is a polymer component containing a fluorine atom or a silicon atom is more preferable. Specific examples include organically modified silicone oil-based, polyacrylate-based, and perfluoroalkyl-based leveling agents. Among these, polyacrylate leveling agents and perfluoroalkyl leveling agents are preferred.

The content of the leveling agent is preferably 0.01 parts by mass or more and 5 parts by mass or less, more preferably 0.05 parts by mass or more and 3 parts by mass or less, and still more preferably 0.01 parts by mass or more and 3 parts by mass or less, based on 100 parts by mass of the polymerizable liquid crystal compound. 05 parts by mass or more and 1 part by mass or less. When the content of the leveling agent is within the above range, it is easy to orient the polymerizable liquid crystal compound, and the resulting optically anisotropic layer 30 tends to be smoother. When the content of the leveling agent in the polymerizable liquid crystal compound exceeds the above range, the resulting optically anisotropic layer 30 tends to be uneven. The composition for forming a liquid crystal cured film may contain two or more types of leveling agents.

By blending an antioxidant, the polymerization reaction of the polymerizable liquid crystal compound can be controlled. The antioxidant may be a primary antioxidant selected from phenolic antioxidants, amine antioxidants, quinone antioxidants, and nitroso antioxidants, or phosphorus antioxidants and A secondary antioxidant selected from sulfur-based antioxidants may also be used. In order to polymerize the polymerizable liquid crystal compound without disturbing the orientation of the polymerizable liquid crystal compound, the content of the antioxidant is usually 0.01 parts by mass or more and 10 parts by mass based on 100 parts by mass of the polymerizable liquid crystal compound. The amount is preferably 0.1 parts by mass or more and 5 parts by mass or less, more preferably 0.1 parts by mass or more and 3 parts by mass or less. Antioxidants can be used alone or in combination of two or more.

By using a photosensitizer, the sensitivity of the photopolymerization initiator can be increased. Examples of the photosensitizer include xanthone such as xanthone and thioxanthone; anthracene having a substituent such as anthracene and alkyl ether; phenothiazine; and rubrene. The photosensitizers can be used alone or in combination of two or more. The content of the photosensitizer is usually 0.01 parts by mass or more and 10 parts by mass or less, preferably 0.05 parts by mass or more and 5 parts by mass or less, more preferably It is 0.1 parts by mass or more and 3 parts by mass or less.

A 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 and a polymerization initiator at a predetermined temperature.

The liquid crystal cured film is, for example,
A coating film of a composition for forming a liquid crystal cured film containing at least one kind of polymerizable liquid crystal compound is formed on the base film or the alignment layer 60 described below, the coating film is dried, and the liquid crystal curing is performed. It can be produced by a method including a step of aligning a polymerizable liquid crystal compound in a film-forming composition, and a step of polymerizing the polymerizable liquid crystal compound while maintaining the alignment state to form a cured liquid crystal film.

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

Examples of the base film include glass base materials and film base materials, with film base materials being preferred and long roll-shaped film base materials being more preferred since they can be produced continuously. Examples of resins constituting the film base material include polyolefins such as polyethylene, polypropylene, and norbornene polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic esters; polyacrylic esters; triacetyl cellulose, diacetyl cellulose and cellulose esters such as cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone; polyether ketone; and plastics such as polyphenylene sulfide and polyphenylene oxide. Among them, a film base material selected from triacetylcellulose, cyclic olefin resin, polymethacrylic acid ester, and polyethylene terephthalate is more preferable from the viewpoint of transparency when used in optical film applications.

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, and more preferably 10 μm or more and 50 μm or less, from the viewpoints of handleability, processability, strength, etc.

Next, a dry coating film is formed by removing the solvent by drying or the like. Examples of the drying method include natural drying, ventilation drying, heating drying, and reduced pressure drying. At this time, by heating the coating film obtained from the composition for forming a liquid crystal cured film, the solvent is dried and removed from the coating film, and the polymerizable liquid crystal compound is directed in a desired direction such as horizontal to the plane of the coating film. It can be oriented to The heating temperature of the coating film can be appropriately determined in consideration of the polymerizable liquid crystal compound used and the material of the base film forming the coating film, etc. Usually, the temperature needs to be higher than the liquid crystal phase transition temperature. In order to bring the polymerizable liquid crystal compound into a desired alignment state while removing the solvent contained in the composition for forming a cured liquid crystal film, for example, the liquid crystal phase transition temperature of the polymerizable liquid crystal compound contained in the composition for forming a cured liquid crystal film may be adjusted. (smectic phase transition temperature or nematic phase transition temperature) or higher. The heating temperature is preferably 3° C. or more, more preferably 5° C. or more higher than the liquid crystal phase transition temperature of the polymerizable liquid crystal compound. The upper limit of the heating temperature is not particularly limited, but is preferably 180° C. or lower, more preferably 150° C. or lower in order to avoid damage to the coating film, base film, etc. due to heating.

Note that the liquid crystal phase transition temperature can be measured using, for example, a polarizing microscope equipped with a temperature control stage, a differential scanning calorimeter (DSC), a thermogravimetric differential thermal analyzer (TG-DTA), or the like. In addition, when using a combination of two or more types of polymerizable liquid crystal compounds, the above phase transition temperature is such that the total polymerizable liquid crystal compound constituting the composition for forming a liquid crystal cured film is mixed in the same proportion as the composition in the composition for forming a liquid crystal cured film. It means the temperature measured using a mixture of polymerizable liquid crystal compounds mixed in the same manner as when one type of polymerizable liquid crystal compound is used. It is also known that, in general, the liquid crystal phase transition temperature of the polymerizable liquid crystal compound in the composition for forming a cured liquid crystal film may be lower than the liquid crystal phase transition temperature of the polymerizable liquid crystal compound alone.

The heating time can be appropriately determined depending on the heating temperature, the type of polymerizable liquid crystal compound used, the type of solvent, its boiling point, its amount, etc., but is usually 0.5 minutes or more and 10 minutes or less, preferably 0. .5 minutes or more and 5 minutes or less.

Removal of the solvent from the coating film may be performed simultaneously with heating the polymerizable liquid crystal compound to a temperature equal to or higher than the liquid crystal phase transition temperature, or may be performed separately, but it is preferably performed simultaneously from the viewpoint of improving productivity. Before heating the polymerizable liquid crystal compound to a temperature higher than the liquid crystal phase transition temperature, the solvent in the coating film is removed under conditions such that the polymerizable liquid crystal compound contained in the coating film obtained from the composition for forming a liquid crystal cured film does not polymerize. A preliminary drying step may be provided to remove the particles appropriately. Examples of the drying method in this preliminary drying step include natural drying, ventilation drying, heating drying, and reduced pressure drying.

Next, in the obtained dry coating film, the polymerizable liquid crystal compound is polymerized by light irradiation while maintaining the orientation state of the polymerizable liquid crystal compound, thereby forming a polymer of the polymerizable liquid crystal compound existing in the desired orientation state. A certain liquid crystal cured film is formed. As the 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, the type of polymerizable liquid crystal compound (especially the type of polymerizable group possessed by the polymerizable liquid crystal compound) and the amount thereof is appropriately selected. Specific examples 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, and active energy rays such as active electron beams. It will be done. Among these, ultraviolet light is preferable because it is easy to control the progress of the polymerization reaction and it is possible to use photopolymerization equipment that is widely used in the field. It is preferable to select the type of polymerizable liquid crystal compound and photopolymerization initiator in advance. Moreover, during polymerization, the polymerization temperature can also be controlled by irradiating the dry coating film with light while cooling it with an appropriate cooling means. By employing such a cooling means and polymerizing the polymerizable liquid crystal compound at a lower temperature, a cured liquid crystal film can be appropriately formed even if a substrate film with relatively low heat resistance is used. It is also possible to promote the polymerization reaction by increasing the polymerization temperature within a range that does not cause problems due to heat during light irradiation (such as deformation of the base film due to heat). A patterned cured film can also be obtained by performing masking or development during photopolymerization.

Examples of active energy ray light sources 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, 380 nm or more and 440 nm. Examples include LED light sources, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps that emit light in the following wavelength ranges.

The ultraviolet irradiation intensity 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 range effective for activating the photopolymerization initiator. The light irradiation time is usually 0.1 seconds or more and 10 minutes or less, preferably 0.1 seconds or more and 5 minutes or less, more preferably 0.1 seconds or more and 3 minutes or less, and even more preferably 0.1 seconds or more. It takes less than 1 minute. When irradiated once or multiple times with such 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 is 100 mJ/cm ² or more and 1,000 mJ/cm ² or less.

The thickness of the optically anisotropic layer 30 (each layer when two or more types of liquid crystal cured films are included) is 0.1 μm or more and 5 μm or less, preferably 0.5 μm or more and 3 μm or less, and more preferably 1.0 μm or more. , more preferably 1.5 μm or more, and more preferably 2.5 μm or less. When the thickness of the liquid crystal cured film is within the above range, predetermined optical properties can be easily developed, and the flexibility of the optical laminate can be easily improved. The thickness of the cured liquid crystal film can be measured using an interference film thickness meter, a laser microscope, a stylus type film thickness meter, or the like.

Like the optical laminate 1 shown in FIG. 1, the optical laminate of the present invention may 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 regulating force that aligns the polymerizable liquid crystal compound in a desired direction. By forming a cured liquid crystal film using a horizontal alignment layer that has an alignment regulating force that aligns the polymerizable liquid crystal compound in the horizontal direction and a vertical alignment layer that has an alignment regulating force that aligns the polymerizable liquid crystal compound in the vertical direction, can be oriented in a desired direction with higher precision, and a cured liquid crystal film that exhibits excellent optical properties when incorporated into an image display device or the like can be obtained. The alignment regulating force can be arbitrarily adjusted by the type of alignment layer, surface condition, rubbing conditions, etc., and if the alignment layer is made of a photo-alignable polymer, it can be arbitrarily adjusted by changing the polarized light irradiation conditions, etc. It is possible to do so.

The state of liquid crystal alignment, such as horizontal alignment, vertical alignment, hybrid alignment, and tilted alignment, changes depending on the properties of the alignment layer 60 and the polymerizable liquid crystal compound, and the combination thereof can be arbitrarily selected. For example, if the alignment layer 60 is made of a material that exhibits horizontal alignment as an alignment regulating force, the polymerizable liquid crystal compound can form horizontal alignment or hybrid alignment; if the alignment layer 60 is a material that exhibits vertical alignment, the polymerizable liquid crystal compound The compounds can form vertical or tilted orientations. Expressions such as horizontal and vertical indicate the direction of the long axis of the oriented polymerizable liquid crystal compound with respect to the plane (principal surface) of the optically anisotropic layer 30. For example, vertical alignment means that the long axis of the polymerizable liquid crystal compound is aligned in a direction perpendicular to the plane (principal surface) of the optically anisotropic layer 30. Vertical here means 90°±20° with respect to the plane (principal surface) of the optically anisotropic layer 30.

As the alignment layer, it is preferable to have a solvent resistance that prevents dissolution by application of the composition for forming a liquid crystal cured film, and a heat resistance in heat treatment for removing the solvent and orienting the polymerizable liquid crystal compound. Examples of the alignment layer include an alignment film containing an alignment polymer, a photo-alignment film, a groove alignment film having a concavo-convex pattern or a plurality of grooves on the surface, and a stretched film stretched in the alignment direction. A photo-alignment film is preferred from the viewpoint of quality.

Examples of oriented polymers include polyamides and gelatins having an amide bond in the molecule, polyimide having an imide bond in the molecule, polyamic acid which is a hydrolyzate thereof, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyacrylamide, etc. Examples include oxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylic esters. Among them, polyvinyl alcohol is preferred. The oriented polymers can be used alone or in combination of two or more.

An alignment film containing an alignment polymer is usually produced by applying a composition in which an alignment polymer is dissolved in a solvent (hereinafter also referred to as an "alignment polymer composition") onto the surface of a base film or the like on which an alignment layer is to be formed. and then removing the solvent, or by applying the oriented polymer composition to a base material, 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 oriented polymer in the oriented polymer composition may be within a range that allows the oriented polymer material to be completely dissolved in the solvent, but it is 0.1% by mass or more and 20% by mass or less in terms of solid content based on the solution. is preferable, and more preferably 0.1% by mass or more and 10% by mass or less.

Examples of the method for applying the oriented polymer composition to the surface on which the oriented layer is to be formed, such as the base film, include the same methods as those exemplified as the method for applying the composition for forming a liquid crystal cured film to the base film. It will be done. Examples of methods for removing the solvent contained in the oriented polymer composition include natural drying, ventilation drying, heating drying, and reduced pressure drying.

In order to impart an alignment regulating force to the alignment layer, rubbing treatment can be performed as necessary (rubbing method). A method of imparting alignment regulating force using the rubbing method is to apply an oriented polymer composition to the base film on a rotating rubbing roll wrapped around a rubbing cloth, and then annealing it to form it on the surface of the base film. An example of this method is to bring a film of an oriented polymer into contact with the film. If masking is performed during the rubbing process, a plurality of regions (patterns) with different orientation directions can be formed in the alignment layer.

A photo-alignment film is usually a composition containing a polymer having a photo-reactive group (photo-alignment polymer) and/or a monomer having a photo-reactive group (photo-alignment monomer) and a solvent (hereinafter referred to as "photo-alignment film"). It can be obtained by coating the surface of the base film on which the alignment layer is to be formed, and irradiating it with polarized light (preferably polarized UV) after removing the solvent. The photo-alignment film is also advantageous in that the direction of the alignment regulating force can be arbitrarily controlled by selecting the polarization direction of the polarized light to be irradiated.

A photoreactive group refers to a group that produces liquid crystal alignment ability when irradiated with light. Specifically, groups that are involved in photoreactions that are the origin of liquid crystal alignment ability, such as molecular orientation induction or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photodecomposition reaction, which are caused by light irradiation, can be mentioned. Among these, groups that participate in a dimerization reaction or a photocrosslinking reaction are preferable because they have excellent orientation. The photoreactive group is preferably a group having an unsaturated bond, especially a double bond, such as a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), or a nitrogen-nitrogen double bond. Particularly preferred is a group having at least one selected from the group consisting of a 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 polyene group, a stilbene group, a stilbazole group, a stilbazolium group, a chalcone group, and a cinnamoyl group. A chalcone group and a cinnamoyl group are preferred from the viewpoint of easy control of reactivity and expression of alignment regulating force during photoalignment. Examples of the photoreactive group having a C=N bond include groups having structures such as an aromatic Schiff base and an aromatic hydrazone. Examples of the photoreactive group having an N=N bond include an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group, a formazan group, and a group having an azoxybenzene structure. Examples of the photoreactive group having a C═O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have a substituent such as an alkyl group, an alkoxy group, an aryl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group, or a halogenated alkyl group.

Furthermore, in order to obtain adhesion to the base film and the optically anisotropic layer 30, the polymer side chain having a photoreactive group may have an adhesion group. Examples of the adhesive group include an epoxy group, an oxetane group, and a (meth)acryloyl group.

Examples of the solvent contained in the composition for forming a photo-alignment film include those similar to the solvents exemplified above as solvents that can be used in the composition for forming a cured liquid crystal film. It can be appropriately selected depending on the solubility of the photo-alignable monomer.

The content of the polymer or monomer having a photoreactive group in the composition for forming a photo-alignment film can be adjusted as appropriate depending on the type of the polymer or monomer and the desired thickness of the photo-alignment film. The content is preferably at least 0.2% by mass, and more preferably 0.3% by mass or more and 10% by mass or less, based on the mass of the product. The composition for forming a photo-alignment film may contain a polymeric material such as polyvinyl alcohol or polyimide, and a photosensitizer as long as the properties of the photo-alignment film are not significantly impaired.

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

In order to irradiate polarized light, polarized UV can be directly irradiated onto the photo-alignment film-forming composition coated on the substrate film from which the solvent has been removed, or polarized light can be irradiated from the base film side. It may also be of a type in which the light is transmitted and irradiated. Moreover, it is preferable that the polarized light is substantially parallel light. The wavelength of the polarized light to be irradiated is preferably in a wavelength range in which a photoreactive group of a photoalignable polymer or a photoalignable monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet light) having a wavelength of 250 nm or more and 400 nm or less is preferable. Examples of the light source used for the polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF, with high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps being preferred. . These lamps are preferable because they emit a high intensity of ultraviolet light with a wavelength of 313 nm. Polarized UV can be irradiated by passing the light from the light source through a suitable polarizer. As such a polarizer, a polarizing filter, a polarizing prism such as Glan-Thompson or Glan-Taylor, or a wire grid type polarizer can be used.

A groove alignment film is a film that has an uneven pattern or a plurality of grooves on its surface. When a polymerizable liquid crystal compound is applied to a film having a plurality of linear grooves arranged at equal intervals, liquid crystal molecules are aligned in the direction along the grooves.

The groove alignment film can be obtained by exposing the surface of a photosensitive polyimide film to light through an exposure mask having pattern-shaped slits, followed by development and rinsing to form a concavo-convex pattern, and by using a plate with grooves on the surface. A method of forming a layer of UV-cured resin before curing on a shaped master, transferring the formed resin layer to a base material, etc., and then curing it, and a method of forming a layer of UV-cured resin before curing on a surface on which an alignment layer is to be formed. Examples include a method in which a roll-shaped master having a plurality of grooves is pressed against a cured resin film to form irregularities, and then hardened.

The thickness of the alignment layer 60 (an alignment film containing an alignment polymer or a photo-alignment film, etc.) is usually 10 nm or more and 10,000 nm or less, preferably 10 nm or more and 2,500 nm or less, more preferably 10 nm or more and 1,000 nm or less, and even more preferably 10 nm or more and 500 nm or less. Hereinafter, it is particularly preferably 50 nm or more and 250 nm or less.

(5) First adhesive layer and second adhesive layer The transparent protective film 10 and the polarizer 20 are laminated with the first adhesive layer 51 in between. Only one adhesive layer 51 is present. Further, the polarizer 20 and the optically anisotropic layer 30 are laminated with a second adhesive layer 52 interposed therebetween, and only the second adhesive layer 52 is interposed between the polarizer 20 and the optically anisotropic layer 30. are doing. Bonding the transparent protective film 10 and the polarizer 20 using the first adhesive layer 51 and bonding the polarizer 20 and the optically anisotropic layer 30 using the second adhesive layer 52 is a method of bonding the optical laminate. This contributes to improving the flexibility, thereby making it difficult for defects such as peeling and cracking to occur in the bent portion even if the bent portion is repeatedly bent. In addition, by bonding the transparent protective film 10 and the polarizer 20 with the first adhesive layer 51 and bonding the polarizer 20 and the optically anisotropic layer 30 with the second adhesive layer 52, these An optical laminate with good adhesion between layers can be obtained.

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

The dry-setting adhesive may contain, for example, a polymer of monomers having a protic functional group such as a hydroxyl group, a carboxyl group, or an amino group and an ethylenically unsaturated group, or a urethane resin as a main component; Examples include compositions containing crosslinking agents or curable compounds such as aldehydes, epoxy compounds, melamine compounds, zirconia compounds, or zinc compounds. Examples of polymers of monomers having a protic functional group such as a hydroxyl group, a carboxyl group, or an amino group and an ethylenically unsaturated group include ethylene-maleic acid copolymers, itaconic acid copolymers, acrylic acid copolymers, and acrylamide. Examples include copolymers, saponified polyvinyl acetate, and polyvinyl alcohol resins. Preferably, it is a polyvinyl alcohol resin.

Examples of polyvinyl alcohol resins include polyvinyl alcohol, partially saponified polyvinyl alcohol, completely saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. Can be mentioned. The content of polyvinyl alcohol resin in the water-based dry-setting adhesive is usually 1 part by mass or more and 10 parts by mass or less, preferably 1 part by mass or more and 5 parts by mass or less, based on 100 parts by mass of water. .

Examples of the urethane resin include polyester-based ionomer-type urethane resins. The polyester-based ionomer type urethane resin referred to herein is a urethane resin having a polyester skeleton into which a small amount of an ionic component (hydrophilic component) is introduced. Such an ionomer-type urethane resin emulsifies in water to form an emulsion without using an emulsifier, and therefore can be used as a water-based dry-setting adhesive. When using a polyester ionomer type urethane resin, it is effective to blend a water-soluble epoxy compound as a crosslinking agent.

Examples of the epoxy compound 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. Commercial products of such polyamide epoxy resins include "SUMIREZ RESIN (registered trademark) 650" and "SUMIRAZE RESIN (registered trademark) 675" (manufactured by Sumika Chemtex Co., Ltd.), and "WS-525" (manufactured by Nippon PMC). Co., Ltd.), etc. When blending an epoxy compound, the amount added is usually 1 part by mass or more and 100 parts by mass or less, preferably 1 part by mass or more and 50 parts by mass or less, per 100 parts by mass of the polyvinyl alcohol resin.

Among these, the dry-setting adhesive is preferably an aqueous dry-setting adhesive containing a polyvinyl alcohol resin.

The dry-setting adhesive may contain a solvent. Examples of the solvent include water, a mixed solvent of water and a hydrophilic organic solvent (for example, an alcohol solvent, an ether solvent, an ester solvent, etc.), an organic solvent, and the like.

An active energy ray-curable adhesive, which is a chemically reactive adhesive, is an adhesive that hardens upon irradiation with active energy rays. The active energy ray curable adhesive may contain a solvent. Examples of active energy ray-curable adhesives include cationically polymerizable adhesives containing an epoxy compound and a cationic polymerization initiator, and radically polymerizable adhesives containing a (meth)acrylic curing component and a radical polymerization initiator. , an adhesive containing both a cationically polymerizable curing component such as an epoxy compound and a radically polymerizable curing component such as a (meth)acrylic compound, and further containing a cationic polymerization initiator and a radical polymerization initiator; Examples include adhesives that do not contain these polymerization initiators and are cured by electron beam irradiation.

Among them, active energy ray-curable adhesives include radically polymerizable active energy ray-curable adhesives containing a (meth)acrylic curing component and a radical polymerization initiator, and active energy ray-curable adhesives containing an epoxy compound and a cationic polymerization initiator. A cationically polymerizable active energy ray-curable adhesive is preferred. Examples of the (meth)acrylic curing component include (meth)acrylates 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 and acrylic compounds.

Examples of the radical polymerization initiator include the photopolymerization initiators described above that can be blended into the liquid crystal cured film forming composition for forming the liquid crystal cured film. Commercially available cationic polymerization initiators include the "Kayarad" (registered trademark) series (manufactured by Nippon Kayaku Co., Ltd.), the "Cylacure UVI" series (manufactured by Dow Chemical Co., Ltd.), the "CPI" series (manufactured by Sun-Apro Co., Ltd.), Examples include "TAZ", "BBI", and "DTS" (manufactured by Midori Kagaku Co., Ltd.), "ADEKA Optomer" series (manufactured by ADEKA Co., Ltd.), and "RHODORSIL" (registered trademark) (manufactured by Rhodia Co., Ltd.). It will be done. The content of the radical polymerization initiator and the cationic polymerization initiator is usually 0.5 parts by mass or more and 20 parts by mass or less, preferably 1 part by mass or more and 15 parts by mass or less, per 100 parts by mass of the active energy ray-curable adhesive. Parts by mass or less.

Using the first adhesive layer 51 for bonding the transparent protective film 10 and the polarizer 20 and using the second adhesive layer 52 for bonding the polarizer 20 and the optically anisotropic layer 30 means that the adhesive Compared to the case where layers are used, it is advantageous in terms of flexibility and thinning of the optical laminate. From the viewpoint of increasing the adhesion between the polarizer 20 and the optically anisotropic layer 30, the second adhesive layer 52 is preferably a layer formed from an active energy ray-curable adhesive, and is a radically polymerizable adhesive. It is more preferable that the layer is formed from an active energy ray-curable adhesive of More preferably, it is a layer that 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, even more preferably 50 nm or more, and preferably 5000 nm or less, more preferably 3000 nm or less, and Preferably it is 2000 nm or less. When the thickness of the adhesive layer, especially the second adhesive layer 52, is within the above range, the flexibility of the optical laminate can be easily improved, so that even if it is repeatedly bent, problems such as peeling and cracks will not occur at the bent part. This can be made less likely to occur. The thicknesses of the first adhesive layer 51 and the second adhesive layer 52 may be the same or different from each other.
The thickness of the adhesive layer can be measured using, for example, an interference thickness meter, a laser microscope, or a stylus thickness meter.

(6) Adhesive Layer The optical laminate includes an adhesive layer 40 disposed on the side of the optically anisotropic layer 30 opposite to the polarizer 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 surface of the optical laminate opposite to the viewing side (transparent protective film 10 side), and is suitable for laminating the optical laminate to an image display element such as an organic EL display element. Can be used.

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

The adhesive layer 40 can be composed of an adhesive composition whose main components are (meth)acrylic resin, rubber resin, urethane resin, ester resin, silicone resin, and polyvinyl ether resin. Among these, a pressure-sensitive adhesive composition whose base polymer is a (meth)acrylic resin having excellent transparency, weather resistance, heat resistance, etc. is suitable. The adhesive composition may be of an active energy ray-curable type or a thermosetting type.

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

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

<Method for manufacturing optical laminate>
The present invention also relates to a method for manufacturing the optical laminate according to the above-described present invention. The method for manufacturing an optical laminate according to the present invention includes the following steps.
a retardation film preparation step of preparing a laminate (hereinafter, this laminate is also referred to as a "retardation film") including an optically anisotropic layer, an alignment layer, and a base film in this order;
a first bonding step of bonding the transparent protective film and the polarizer using a first adhesive;
a second bonding step of bonding the polarizer and the optically 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 lamination step;
An adhesive layer lamination process in which an adhesive layer is laminated on the surface exposed by the peeling process.

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

The first adhesive used in the first bonding 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 radically polymerizable active energy ray-curable adhesive, and includes a (meth)acrylic curing component and a radical polymerization initiator. More preferably, it is a radically polymerizable active energy ray-curable adhesive containing.

When the first adhesive is a dry-setting adhesive, after laminating (laminating) the transparent protective film and the polarizer via the first adhesive, the solvent in the first adhesive is removed from the resulting laminate. Dry, remove and optionally cure. This drying treatment and/or removal of the solvent can be performed, for example, by blowing hot air, and the temperature depends on the type of solvent, but is usually 30°C or higher and 200°C or lower, preferably 35°C or higher and 150°C or higher. The temperature is preferably 40°C or higher and 100°C or lower, and even more preferably 50°C or higher and 100°C or lower.

The drying and removal (curing in some cases) of the solvent in the first adhesive is carried out after performing a second lamination step of laminating (laminating) the polarizer and the retardation film via the second adhesive. It is preferable to carry out this process together with drying and removal (and in some cases, curing) of the solvent in the second adhesive.

When the first adhesive is an active energy ray-curable adhesive, the first adhesive layer is obtained by curing the first adhesive by irradiating the active energy ray. Although the light source of active energy rays is not particularly limited, active energy rays having an emission distribution at a wavelength of 400 nm or less are preferable, and ultraviolet rays are more preferable. 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 intensity of light irradiation to the active energy ray curable adhesive is appropriately determined depending on the composition of the active energy ray curable adhesive, and is not particularly limited, but the irradiation intensity in the wavelength range effective for activating the polymerization initiator is usually , 10 mW/cm ² or more and 3,000 mW/cm ² or less. The light irradiation time to the active energy ray curable adhesive may be selected appropriately depending on the active energy ray curable adhesive to be cured, and is not particularly limited, but is usually 0.1 seconds or more and 10 minutes or less. , preferably 1 second or more and 5 minutes or less, more preferably 5 seconds or more and 3 minutes or less, and even more preferably 10 seconds or more and 1 minute or less. When irradiated once or multiple times with such ultraviolet irradiation intensity, the cumulative light amount is usually 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, or more. Preferably it is 100 mJ/cm ² or more and 1,000 mJ/cm ² or less.

The first adhesive is cured by irradiation with active energy rays after performing a second laminating step of laminating (laminating) the polarizer and the retardation film via the second adhesive. Preferably, this is carried out together with the curing of the inside.

The second bonding step can be performed in the same manner as the first bonding step. In one embodiment, the first bonding step and the second bonding step are performed simultaneously. The second adhesive is an adhesive forming 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 radically polymerizable active energy ray-curable adhesive, and includes a (meth)acrylic curing component and a radical polymerization initiator. More preferably, it is a radically polymerizable active energy ray-curable adhesive containing. The first adhesive and the second adhesive may be different adhesives, but are preferably the same adhesive.

Through the first bonding step and the second bonding step, a laminate having a layer structure of transparent protective film/first adhesive/polarizer/second adhesive/retardation film is obtained. For this laminate, before the peeling step, the solvents of the first adhesive and the second adhesive are dried, removed (cured in some cases), or cured by irradiation with active energy rays.

In one embodiment, when the first adhesive and the second adhesive are active energy ray-curable adhesives, and the first adhesive and the second adhesive included in the laminate are cured by irradiation with active energy rays, , the active energy ray is 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 has ultraviolet absorbing ability, such as when it contains an ultraviolet absorber. .

For the laminate, which has been cured by drying or removing (curing in some cases) the solvent of the first adhesive and the second adhesive, or by irradiating active energy rays, the base film or the base film is removed in the peeling process. Then, the alignment layer is peeled off and removed, and an adhesive layer is laminated on the surface exposed by the peeling process, thereby obtaining an optical laminate. When the base film is peeled off in the peeling process, an optical laminate including the alignment layer 60 as shown in FIG. 1 is obtained, and when the base film and the alignment layer are peeled off and removed in the peeling process, In this case, an optical laminate without the alignment layer 60 as shown in FIG. 2 is obtained.

The optical laminate can be manufactured continuously using a roll-to-roll method. For example, a retardation film wound into a roll is produced, this retardation film is unwound and conveyed, and an adhesive is used to bond each layer to a separately produced polarized light film on the retardation film. After sequentially laminating the protective film and the transparent protective film, the adhesive is dried or cured, and then the base film or the base film and alignment layer are peeled off, and an adhesive layer is laminated on the surface exposed by peeling. The method allows optical laminates to be manufactured continuously. Thus, in one embodiment, the optical laminate may be in the form of a rolled optical laminate roll.

In one embodiment, it is preferable to laminate the optical laminate so that the angle between the slow axis (optical axis) of the optically anisotropic layer constituting the optical laminate and the absorption axis of the polarizer is 45±5°.

<Image display device>
The optical laminate of the present invention can be used in an image display device. An image display device is a device having an image display element, and includes a light emitting element or a light emitting device as a light source. Image display devices include liquid crystal display devices, organic electroluminescence (EL) display devices, inorganic electroluminescence (EL) display devices, touch panel display devices, and electron emission display devices (e.g., field emission displays (FEDs), surface field emission displays). display device (SED)), electronic paper (display device using electronic ink or electrophoretic element), plasma display device, projection type display device (e.g. grating light valve (GLV) display device, digital micromirror device (DMD)) display devices), piezoelectric ceramic displays, etc. The liquid crystal display device may be any of a transmissive liquid crystal display device, a transflective liquid crystal display device, a reflective liquid crystal display device, a direct view liquid crystal display device, a projection liquid crystal display device, and the like. These display devices may be display devices that display two-dimensional images, or may be stereoscopic display devices that display three-dimensional images. In particular, the optical laminate of the present invention can be suitably used for organic electroluminescent (EL) display devices, inorganic electroluminescent (EL) display devices, liquid crystal display devices, and touch panel display devices.

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

The flexible image display device includes, for example, a laminate for a flexible image display device and an organic EL display panel, the laminate for a flexible image display device is arranged on the viewing side of the organic EL display panel, and is configured to be foldable. has been done. In addition to the optical laminate of the present invention, the laminate for a flexible image display device may include a window, a touch sensor, and the like. Although the order of stacking them is arbitrary, it is preferable that they are stacked in the order of the window, the optical laminate, and the touch sensor from the viewing side, or in the order of the window, the touch sensor, and the elliptically polarizing plate.

It is preferable that the optical laminate is present on the viewing side of the touch sensor because the pattern of the touch sensor becomes less visible and the visibility of the displayed image improves. Each member can be laminated using an adhesive, a pressure-sensitive adhesive, or the like. Further, the laminate for a flexible image display device can include a light-shielding pattern formed on at least one surface of any one of the window, optical laminate, and touch sensor layer.

A window is usually placed on the viewing side of a flexible image display device, and has the role of protecting other components from external shocks or environmental changes such as temperature and humidity. The window is made of a flexible transparent base material and may include a hard coat layer on at least one surface. The window, touch sensor, etc. that constitute the laminate for a flexible image display device are not particularly limited, and conventionally known ones can be employed.

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

<Example 1>
[Preparation of photoalignment film forming composition (X)]
A photoalignable material having the following structure (weight average molecular weight: 50000, m:n=50:50) was produced according to the method described in JP-A-2021-196514. A composition (X) for forming a photo-alignment film was prepared by mixing 2 parts of the photo-alignment material and 98 parts of cyclopentanone (solvent), and stirring the resulting mixture at 80° C. for 1 hour.
Photoalignable material:

[Manufacture of polymerizable liquid crystal compound]
A polymerizable liquid crystal compound (A1) and a polymerizable liquid crystal compound (A2) having the structures shown below were respectively prepared. The polymerizable liquid crystal compound (A1) was prepared in the same manner as the method described in JP-A-2019-003177. Polymerizable liquid crystal compound (A2) was prepared in the same manner as described in JP-A-2009-173893.
Polymerizable liquid crystal compound (A1):

Polymerizable liquid crystal compound (A2):

A solution was obtained by dissolving 1 mg of polymerizable liquid crystal compound (A1) in 10 mL of chloroform. The obtained solution was placed in a measurement cell with an optical path length of 1 cm, and the measurement sample was set in an ultraviolet-visible spectrophotometer ("UV-2450" manufactured by Shimadzu Corporation) to measure the absorption spectrum. When the wavelength at which the maximum absorption occurs was read from the obtained absorption spectrum, 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)]
A polymerizable liquid crystal compound (A1) and a 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, 0.1 part of a leveling agent "BYK-361N" (manufactured by BM Chemie) and 3 parts of "Irgacure OXE-03" (manufactured by BASF Japan Co., Ltd.) as a photopolymerization initiator were added. Added. Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration was 13%. A liquid crystal cured film forming composition (Y) was prepared by stirring this mixture at a temperature of 80° C. for 1 hour. Table 1 shows the composition (other than the solvent) of the composition (Y) for forming a liquid crystal cured film.

[Production of retardation film (Z)]
The photo-alignment film forming composition (X) was applied to a biaxially oriented polyethylene terephthalate (PET) film (Diafoil, manufactured by Mitsubishi Plastics Co., Ltd.) as a base film using a bar coater. The obtained coating film was dried at 120° C. for 2 minutes, and then cooled to room temperature to form a dry film. Thereafter, 100 mJ of polarized ultraviolet light (313 nm standard) was irradiated using a UV irradiation device (SPOT CURE SP-9; manufactured by Ushio Inc.) to obtain a photoalignment film D. The thickness of the photo-alignment film D was 200 nm as measured using an ellipsometer M-220 manufactured by JASCO Corporation.

The above composition for forming a liquid crystal cured film was applied onto the obtained photo-alignment film using a bar coater to form a coating film. This coating film was dried by heating at 120° C. for 2 minutes, and then cooled to room temperature to obtain a dry film. Next, using a high-pressure mercury lamp (Unicure VB-15201BY-A manufactured by Ushio Inc.), the dried film is irradiated with ultraviolet light at an exposure amount of 500 mJ/cm ² (365 nm standard) in a nitrogen atmosphere. to form an optically anisotropic layer that is cured with the polymerizable liquid crystal compound oriented in the horizontal direction with respect to the plane of the substrate, and then A retardation film (Z) consisting of a film) was obtained. The thickness of the optically anisotropic layer measured using a laser microscope LEXT OLS4100 manufactured by Olympus Corporation was 2.0 μm.

Corona treatment was performed on the liquid crystal side of the retardation film (Z), and it was bonded to glass via a 25 μm thick pressure-sensitive adhesive manufactured by Lintec, and the PET film was peeled off and removed. The in-plane phase difference value was measured using KOBRA-WR manufactured by Oji Scientific Instruments Co., Ltd. The in-plane retardation values for light with wavelengths of 450 nm, 550 nm, and 650 nm are It was calculated using Cauchy's dispersion formula obtained from the measurement results.
As a result, the in-plane retardation values are Re (450) = 122 nm, Re (550) = 140 nm, and Re (650) = 144 nm, and the relationship between the in-plane retardation values at each wavelength is as follows. Ta.
Re(450)/Re(550)=0.87
Re(650)/Re(550)=1.03
(In the formula, Re (450) is the in-plane retardation value for light with a wavelength of 450 nm, Re (550) is the in-plane retardation value for light with a wavelength of 550 nm, and Re (650) is the in-plane retardation value for light with a wavelength of 650 nm. (Represents the phase difference value.)

[Preparation of polarizer]
A polyvinyl alcohol film (PVA: average polymerization degree of about 2400, saponification degree of 99.9 mol% or more) with a thickness of 30 μm was uniaxially stretched to about 5 times by dry stretching, and then kept under tension in a pure state at 40°C. Immersed in water for 40 seconds. Thereafter, it was immersed in a dyeing aqueous solution having a mass ratio of iodine/potassium iodide/water of 0.044/5.7/100 at 28° C. for 30 seconds to perform a dyeing treatment. Next, it was immersed in a boric acid aqueous solution having a mass ratio of potassium iodide/boric acid/water of 11.0/6.2/100 at 70° C. for 120 seconds. Subsequently, after washing with pure water at 8°C for 15 seconds, the polyvinyl alcohol film was dried at 60°C for 50 seconds and then at 75°C for 20 seconds while being held under a tension of 300N, so that iodine was adsorbed and oriented in the polyvinyl alcohol film. A polarizer with a thickness of 12 μm was obtained.

[Preparation of optical laminate]
The retardation film (Z) produced above, the polarizer, and the saponified triacetyl cellulose film (TAC: "KC4UY" manufactured by Konica Minolta Opto Co., Ltd., thickness 40 μm) as a transparent protective film were placed in this order. After the liquid crystal cured film side of the retardation film is subjected to corona treatment, the liquid crystal cured film side of the retardation film and the polarizer are opposed to each other, and the side of the polarizer opposite to the retardation film is treated with a transparent protective film. They were stacked so that they were facing each other. At this time, a water-based dry-setting adhesive was injected between the cured liquid crystal film and the polarizer and between the polarizer and the transparent protective film. Further, these were laminated so that the absorption axis of the polarizer and the slow axis of the cured liquid crystal film in the retardation film formed an angle of 45°. The obtained laminate was passed through nip rolls to bond each layer together. The resulting bond was dried at 60° C. for 2 minutes while maintaining the tension at 430 N/m. After that, only the base film (PET film) of the retardation film is peeled off, and an adhesive layer with a separate film is laminated on the surface exposed by peeling. An optical laminate (1) consisting of layer (cured liquid crystal film)/adhesive layer/polarizer/adhesive layer/transparent protective film was obtained. The thickness of the optical laminate (1) excluding the adhesive layer was 54 μm.

The above water-based dry-setting adhesive is made of 100 parts of water, 3 parts of carboxyl group-modified polyvinyl alcohol (Kuraray Poval KL318; manufactured by Kuraray Co., Ltd.), and a water-soluble polyamide epoxy resin (Sumirezu Resin 650; Sumika Chemtex Co., Ltd.). 1.5 parts of an aqueous solution with a solid content concentration of 30%) was added.

[Evaluation of optical laminate]
(1) Flexibility evaluation Flexibility evaluation was performed using a bending tester (“CFT-720C” (trade name) manufactured by Covotech) with the transparent protective film side of the optical laminate (1) facing inside. Tested by bending. The adhesive layer side of the optical laminate (1) from which the separate film had been peeled was bonded in a flat state (not bent) on a sample stage of a bending tester. The optical laminate (1) was bent by 180° so that when the optical laminate (1) was bent, the distance between the opposing transparent protective films was 4.0 mm (bending radius R=2 mm). It was then returned to its original flat state. The number of times of bending was counted as one time when the series of operations were performed once, and this bending operation was repeated. The bending speed was 60 rpm. The number of bending times when cracks or lifting of the adhesive layer occurred in the area bent by the bending operation was recorded as the limit number of bending times. The limit number of bends was evaluated according to the following criteria.
A: No cracks or lifts occur even after 100,000 bends B: Cracks or lifts occur after 80,000 or more bends but less than 100,000 times C: Cracks or lifts occur after 50,000 or more bends but less than 80,000 times D: Cracks and lifting occur when the number of bends is 10,000 to less than 50,000 times. E: Cracks and lifting occur when the number of bends is less than 10,000 times.

(2) Adhesion evaluation Before forming the adhesive layer on the photo-alignment film of the optical laminate (1), cut out a sample piece from an arbitrary location and cross-cut it with the optically anisotropic layer according to JIS K 5600 cross-cut method. Adhesion to the polarizer was evaluated. The specific evaluation criteria were as follows. The results are shown in Table 2. The adhesion between the optically anisotropic layer and the polarizer of the optical laminate (1) was B.
A: No peeling on any grid B: Partial peeling of the paint film (1% or more and less than 50%)
C: The paint film has completely peeled off (50% or more)

<Example 2>
An optical laminate (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 the transparent protective film. , conducted an evaluation. The results are shown in Table 2.

<Example 3>
An optical laminate (3) was produced in the same manner as in Example 1, except that a corona-treated cyclic polyolefin resin film (COP: ZF-14 manufactured by Nippon Zeon, thickness 40 μm) was used as the transparent protective film. , conducted an evaluation. The results are shown in Table 2.

<Example 4>
An optical laminate (4) was produced in the same manner as in Example 1, except that a corona-treated polyethylene terephthalate film (PET: Diafoil, manufactured by Mitsubishi Plastics Co., Ltd., thickness 38 μm) was used as the transparent protective film. and evaluated it. The results are shown in Table 2.

<Example 5>
A retardation film (Z), a polarizer, and a triacetyl cellulose film (TAC: "KC4UY" manufactured by Konica Minolta Opto Co., Ltd.) that has been saponified as a transparent protective film are cured in this order by liquid crystal curing of the retardation film. After corona treatment of the film side, lamination is performed so that the cured liquid crystal film side of the retardation film faces the polarizer, and the side of the polarizer opposite to the retardation film faces the transparent protective film. did. At this time, a radically polymerizable ultraviolet curable adhesive was injected between the liquid crystal cured film and the polarizer and between the polarizer and the transparent protective film. Further, these were laminated so that the absorption axis of the polarizer and the slow axis of the cured liquid crystal film in the retardation film formed an angle of 45°. The obtained laminate was passed through nip rolls to bond each layer together. The obtained bonded product was irradiated with ultraviolet rays at an exposure dose of 1000 mJ from the retardation film side. After that, only the base film (PET film) of the retardation film is peeled off, and an adhesive layer with a separate film is laminated on the surface exposed by peeling. An optical laminate (5) consisting of layer (cured liquid crystal film)/adhesive layer/polarizer/adhesive layer/transparent protective film was obtained. The thickness of the optical laminate (5) excluding the adhesive layer was 56 μm.

The radically polymerizable ultraviolet curable adhesive is an ultraviolet curable adhesive containing a (meth)acrylic curing component and a radical polymerization initiator, which was prepared by mixing the following components.
Acryloylmorpholine (manufactured by Kojinsha) 23.1 parts Isostearyl acrylate (manufactured by Osaka Organic Chemical Industry) 31.1 parts Light acrylate LA: Lauryl acrylate (manufactured by Kyoei Chemical) 7.7 parts 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 Kyoei Kagaku) 15.0 parts ARUFON-UP1190: Acrylic polymer (manufactured by Toagosei) 15. Part 3 IRGCURE. 907: 2-Methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (manufactured by BASF) 3.5 parts KAYACURE DETX-S: Diethylthioxanthone (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 the transparent protective film. and evaluated it. 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 the transparent protective film. , conducted an evaluation. The results are shown in Table 2.

<Example 8>
An optical laminate (8) was produced in the same manner as in Example 5, except that a corona-treated polyethylene terephthalate film (PET: Diafoil, manufactured by Mitsubishi Plastics Co., Ltd., thickness 38 μm) was used as the transparent protective film. and conducted an evaluation. The results are shown in Table 2.

<Example 9>
A retardation film (Z), a polarizer, and a triacetyl cellulose film (TAC: "KC4UY" manufactured by Konica Minolta Opto Co., Ltd.) that has been saponified as a transparent protective film are cured in this order by liquid crystal curing of the retardation film. After corona treatment of the film side, lamination is performed so that the cured liquid crystal film side of the retardation film faces the polarizer, and the side of the polarizer opposite to the retardation film faces the transparent protective film. did. At this time, a cationically polymerizable ultraviolet curable adhesive was injected between the cured liquid crystal film and the polarizer and between the polarizer and the transparent protective film. Further, these were laminated so that the absorption axis of the polarizer and the slow axis of the cured liquid crystal film in the retardation film formed an angle of 45°. The obtained laminate was passed through nip rolls to bond each layer together. While maintaining the tension of the obtained bond at 430 N/m, ultraviolet rays were irradiated from the optically anisotropic layer side at an exposure dose of 1000 mJ. After that, only the base film (PET film) of the retardation film is peeled off, and an adhesive layer with a separate film is laminated on the surface exposed by peeling. An optical laminate (9) consisting of layer (cured liquid crystal film)/adhesive layer/polarizer/adhesive layer/transparent protective film was obtained. The thickness of the optical laminate (9) excluding the adhesive layer was 55 μm.

The above-mentioned cationic polymerizable ultraviolet curable adhesive is an ultraviolet curable adhesive containing an epoxy compound and a cationic polymerization initiator, prepared by mixing the following components.
3,4-Epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate 40 parts Diglycidyl ether of bisphenol A 60 parts Diphenyl (4-phenylthiophenyl) sulfonium hexafluoroantimonate (photocationic polymerization initiator) 4 parts

<Example 10>
An optical laminate (10) was produced in the same manner as in Example 9, except that a corona-treated polymethyl methacrylate resin film (PMMA: manufactured by Sumitomo Chemical Co., Ltd., thickness 40 μm) was used as the transparent protective film. and evaluated it. The results are shown in Table 2.

<Example 11>
An optical laminate (11) was produced in the same manner as in Example 9, except that a corona-treated cyclic polyolefin resin film (COP: ZF-14 manufactured by Nippon Zeon, thickness 40 μm) was used as the transparent protective film. , conducted an evaluation. The results are shown in Table 2.

<Example 12>
An optical laminate (12) was produced in the same manner as in Example 9, except that a corona-treated polyethylene terephthalate film (PET: Diafoil, manufactured by Mitsubishi Plastics Co., Ltd., thickness 38 μm) was used as the transparent protective film. and evaluated it. The results are shown in Table 2.

<Comparative example 1>
An adhesive layer with a separate film was laminated on the base film surface of a laminate produced according to Example 2 of JP-A-2022-044293 to obtain an optical laminate (13). The layer structure of the optical laminate (13) is adhesive layer with separate film/base film/photo alignment film/optical anisotropic layer (cured liquid crystal film)/adhesive layer/polarizer/adhesive layer/transparent protection. It's a film.

<Comparative example 2>
An adhesive layer with a separate film was laminated on the optically anisotropic layer (cured liquid crystal film) surface of a laminate produced according to Example 1 of JP-A-2022-044293 to obtain an optical laminate (14). The layer structure of the optical laminate (14) is adhesive layer with separate film/optically anisotropic layer (cured liquid crystal film)/photo alignment film/base film/adhesive layer/polarizer/adhesive layer/transparent protection. It's a film.

<Comparative example 3>
An adhesive layer with a separate film was laminated on the base film surface of a laminate produced according to Example 3 of JP-A-2022-044293 to obtain an optical laminate (15). The layer structure of the optical laminate (15) is adhesive layer with separate film/base film/photo alignment film/optical anisotropic layer (cured liquid crystal film)/adhesive layer/polarizer/adhesive layer/transparent protection. It's a film.

<Comparative example 4>
An adhesive layer with a separate film was laminated on the base film surface of a laminate produced according to Example 4 of JP-A-2022-044293 to obtain an optical laminate (16). The layer structure of the optical laminate (16) is adhesive layer with separate film/base film/photo alignment film/optical anisotropic layer (cured liquid crystal film)/adhesive layer/polarizer/adhesive layer/transparent protection. It's a film.

<Comparative example 5>
An optical laminate (17) was obtained by laminating an adhesive layer with a separate film on the photo-alignment film surface of a laminate produced according to Comparative Example 1 of JP-A-2022-044293. The layer structure of the optical laminate (17) is adhesive layer with separate film/photo alignment film/optically anisotropic layer (cured liquid crystal film)/adhesive layer/polarizer/adhesive layer/transparent protective film.

1, 2 Optical laminate, 10 Transparent protective film, 20 Polarizer, 30 Optically anisotropic layer, 40 Adhesive layer, 51 First adhesive layer, 52 Second adhesive layer, 60 Orientation layer.

Claims

An optical laminate comprising a transparent protective film, a first adhesive layer, a polarizer, 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 polarizer, and only the second adhesive layer is interposed between the polarizer and the optically anisotropic layer,
The optically anisotropic layer is a liquid crystal cured film,
The thickness of the optically anisotropic layer is 0.1 μm or more and 5 μm or less,
The optical laminate, wherein the optically anisotropic layer and the adhesive layer are in direct contact with each other, or an alignment layer is provided between the optically anisotropic layer and the adhesive layer.
The optical laminate according to claim 1, wherein the first adhesive layer and the second adhesive layer have a thickness of 50 nm or more and 2000 nm or less.
The optical laminate according to claim 1, wherein the first adhesive layer and the second adhesive layer are layers formed from a dry-setting adhesive or an active energy ray-curing adhesive.
The optical laminate according to claim 1, wherein the optically anisotropic layer has reverse wavelength dispersion.
The optical laminate according to claim 1, wherein the optically anisotropic layer has an in-plane retardation value of 100 nm or more and 160 nm or less for light with a wavelength of 550 nm.
The optical laminate according to claim 1, wherein the optically anisotropic layer has an optical axis oblique to the longitudinal direction of the polarizer.
The optical laminate according to claim 1, wherein the alignment layer is a photoalignment film made of a photoalignable polymer containing a photoreactive group.
The optical laminate according to claim 1, further comprising an antireflection layer on a side of the transparent protective film opposite to the polarizer.
The optical laminate according to claim 1, wherein the polarizer is composed of a polyvinyl alcohol resin film containing a dichroic dye.
An image display device comprising the optical laminate according to any one of claims 1 to 9.
A method for producing an optical laminate according to any one of claims 1 to 9, comprising:
a retardation film preparation step of preparing a retardation film including an optically anisotropic layer, an alignment layer, and a base film in this order;
a first bonding step of bonding the transparent protective film and the polarizer using a first adhesive;
a second bonding step of bonding the polarizer and the optically 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 bonding step;
an adhesive layer lamination step of laminating the adhesive layer on the surface exposed by the peeling step;
A method for producing an optical laminate, comprising:
The method for manufacturing an optical laminate according to claim 11, wherein the first adhesive and the second adhesive are active energy ray-curable adhesives.
After the second bonding step and before the peeling step, active energy rays are irradiated from the retardation film side of the laminate obtained in the second bonding step to remove the first adhesive and The method for manufacturing an optical laminate according to claim 12, further comprising the step of curing the second adhesive.