CN118259394A

CN118259394A - Optical laminate and image display device

Info

Publication number: CN118259394A
Application number: CN202311777626.9A
Authority: CN
Inventors: 田中贵景; 祖父江彰二; 斋藤宗祐
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2022-12-27
Filing date: 2023-12-21
Publication date: 2024-06-28

Abstract

The invention provides an optical laminate and an image display device comprising the same, wherein the optical laminate comprises a polarizer, a protective film and a phase element, and can reduce warpage in a single body. Provided are an optical laminate comprising a polarizing plate, a protective film, and a phase element in this order, wherein the thickness T1 of the polarizing plate is 15 [ mu ] m or less, and wherein the tensile elastic modulus at a temperature of the protective film of 85 ℃ is E [ MPa ], and the thickness is T2[ mu ] m, and an image display device comprising the optical laminate, wherein the optical laminate satisfies the following formula (i): e x T2 is less than or equal to 8000 and formula (ii): t2 is less than or equal to 7.

Description

Optical laminate and image display device

Technical Field

The present invention relates to an optical laminate and an image display device including the same.

Background

In image display devices such as organic EL display devices, it is known that a circularly polarizing plate is used to improve antireflection performance in order to suppress a decrease in visibility due to reflection of external light (for example, patent document 1). The circular polarizing plate is an optical laminate including a polarizing plate and a phase element (japanese: phase).

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2022-101448

Disclosure of Invention

Problems to be solved by the invention

The present invention aims to provide an optical laminate including a polarizing plate, a protective film, and a phase element, which can reduce warpage in a monolithic body, and an image display device including the optical laminate.

Means for solving the problems

The present invention provides the following.

[1] An optical laminate comprising a polarizing plate, a protective film, and a phase element in this order,

The thickness T1 of the polarizing plate is 15 μm or less,

When the tensile elastic modulus of the protective film at a temperature of 85 ℃ is E [ MPa ] and the thickness is T2[ mu ] m, the following formulas (i) and (ii) are satisfied:

E×T2≤8000 (i)

T2≤7 (ii)。

[2] the optical laminate according to [1], wherein E.times.T2 has a value of 1850 or less.

[3] The optical laminate according to [1] or [2], wherein the phase element comprises a phase difference film.

[4] The optical laminate according to any one of [1] to [3], wherein the protective film comprises a cyclic polyolefin resin.

[5] The optical laminate according to any one of [1] to [4], wherein the protective film has an in-plane phase difference value of 10nm or less at a wavelength of 550 nm.

[6] The optical laminate according to any one of [1] to [5], which comprises an adhesive layer between the polarizer and the protective film.

[7] The optical laminate according to any one of [1] to [6], wherein the boron content of the polarizing plate is 0.5 mass% or more and 5.5 mass% or less.

[8] An optical laminate with an adhesive layer comprising:

[1] The optical laminate according to any one of [7 ]; and

An adhesive layer laminated on the opposite side of the phase element from the protective film side,

When the storage modulus of the pressure-sensitive adhesive layer at a temperature of 23 ℃ is G' [ MPa ] and the thickness is T3[ mu ] m, the following formula (iii) is satisfied:

G’/T3≤5(iii)。

[9] An image display device comprising the optical laminate according to any one of [1] to [7 ].

[10] An image display device comprising the optical laminate with an adhesive layer according to [ 8].

Effects of the invention

An optical laminate including a polarizing plate, a protective film, and a phase element, which can reduce warpage in a monolithic body, and an image display device including the optical laminate can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of the layer structure of the optical laminate of the present invention.

Fig. 2 is a schematic cross-sectional view showing an example of the layer structure of the optical laminate with an adhesive layer of the present invention.

Fig. 3 is a diagram for explaining a measurement sample used for measuring the tensile elastic modulus of the protective film.

Detailed Description

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 understanding the present invention, and the size and shape of each component shown in the drawings do not necessarily coincide with the size and shape of the actual component.

Optical laminate and optical laminate with adhesive layer

(1) Summary of the inventionsummary

Fig. 1 is a schematic cross-sectional view showing an example of layer configuration of an optical laminate (hereinafter, also simply referred to as "optical laminate") of the present invention. The optical laminate shown in fig. 1 includes a polarizing plate 10, a protective film 20, and a phase element 30 in this order. The optical laminate can be suitably used as a circularly polarizing plate. The term "circular polarizing plate" includes elliptical polarizing plates. The optical laminate can be used as an antireflection film or the like in an image display device such as an organic electroluminescence (organic EL) display device.

The optical laminate shown in fig. 1 includes a1 st adhesive layer 41 between the polarizer 10 and the protective film 20. The polarizer 10 is preferably in direct contact with the 1 st adhesive layer 41, and the 1 st adhesive layer 41 is preferably in direct contact with the protective film 20. The optical laminate of the present invention may not have the 1 st adhesive layer 41, in which case the polarizing plate 10 is in direct contact with the protective film 20.

The optical laminate shown in fig. 1 includes a2 nd adhesive layer 42 between the protective film 20 and the phase element 30. The protective film 20 is preferably in direct contact with the 2 nd adhesive layer 42, and the 2 nd adhesive layer 42 is preferably in direct contact with the phase element 30.

The optical laminate may have another protective film on the opposite side of the polarizer 10 from the protective film 20. The other protective film is preferably laminated to the polarizing plate 10 via an adhesive layer. In the case where the polarizer 10 does not have another protective film on the side opposite to the protective film 20 side, it is advantageous from the viewpoint that the processability such as decoloration of the polarizer 10 can be achieved.

Fig. 2 is a schematic cross-sectional view showing an example of the layer structure of the adhesive layer-attached optical laminate of the present invention (hereinafter, also simply referred to as "adhesive layer-attached optical laminate"). The optical laminate with an adhesive layer of the present invention further comprises an adhesive layer laminated on the opposite side of the phase element of the optical laminate of the present invention from the protective film side. The optical laminate with an adhesive layer shown in fig. 2 further includes an adhesive layer 50 laminated on the opposite side of the phase element 30 of the optical laminate shown in fig. 1 from the protective film 20 side.

In the optical laminate and the optical laminate with an adhesive layer of the present invention, the thickness T1 of the polarizing plate 10 is 15 μm or less, and when the tensile elastic modulus of the protective film 20 at a temperature of 85 ℃ is E [ MPa ] and the thickness is T2[ mu ] m, the following formulas (i) and (ii) are satisfied:

E×T2≤8000 (i)

T2≤7 (ii)。

According to the present invention, an optical laminate and an optical laminate with an adhesive layer, in which warpage is reduced in a monolithic body, can be provided. Hereinafter, elements constituting or capable of constituting the optical laminate and the optical laminate with an adhesive layer will be described in detail.

(2) Polarizing plate

The polarizing plate 10 is an optical film (linear polarizing plate) having a property of transmitting linearly polarized light having a vibration plane orthogonal to an absorption axis when unpolarized light is incident. The polarizing plate is preferably a polyvinyl alcohol resin film (hereinafter also referred to as "PVA-based film") in which a dichroic dye is adsorbed and oriented.

A polyvinyl alcohol resin (hereinafter also referred to as "PVA-based resin") constituting the PVA-based film can be produced by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate resin may be a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group.

In the present specification, "(meth) acrylic acid" means either acrylic acid or methacrylic acid. (meth) acrylate and the like are also defined as "(meth)" as well.

The saponification degree of the PVA-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The PVA-based resin may be modified, and for example, polyvinyl formal, polyvinyl acetal, or the like modified with an aldehyde may be used. The average polymerization degree of the PVA-based resin is usually about 1000 to 10000, preferably about 1500 to 5000. The average polymerization degree of the PVA based resin can be determined according to JIS K6726 (1994). If the average polymerization degree is less than 1000, it is difficult to obtain preferable polarization properties, and if it exceeds 10000, film processability may be poor.

The polarizing plate is generally manufactured by the following steps: a step of uniaxially stretching the PVA film; a step of adsorbing a dichroic dye by dyeing the PVA film with the dichroic dye; a step of treating the PVA film having the dichroic dye adsorbed thereto with an aqueous boric acid solution to crosslink the PVA film; and a step of performing water washing after the crosslinking treatment with an aqueous boric acid solution (hereinafter, also referred to as boric acid treatment).

The uniaxial stretching of the PVA-based film may be performed before dyeing with a dichroic dye, simultaneously with dyeing, or after dyeing. In the case of uniaxial stretching after dyeing, the uniaxial stretching may be performed before boric acid treatment or may be performed in boric acid treatment. Of course, the uniaxial stretching may be performed in a plurality of stages as shown here. The uniaxial stretching may be performed by a method in which uniaxial stretching is performed in the film conveying direction between rolls having different peripheral speeds, a method in which uniaxial stretching is performed in the film conveying direction using a hot roll, a method in which stretching is performed in the width direction using a tenter, or the like. The uniaxial stretching may be performed by dry stretching in which stretching is performed in the atmosphere, or may be performed by wet stretching in which stretching is performed in a state in which a PVA-based film is swollen with a solvent such as water. The stretching ratio is usually about 3 to 8 times.

Dyeing of the PVA film with the dichroic dye can be performed, for example, by immersing the PVA film in an aqueous solution containing the dichroic dye. As the dichroic dye, specifically, iodine and a dichroic organic dye can be used. The PVA-based film is preferably subjected to a treatment of swelling by immersing in water before the dyeing treatment.

In the case of using iodine as a dichroic dye, a method of immersing a PVA-based film in an aqueous solution containing iodine and potassium iodide is generally employed for dyeing. The iodine content of the aqueous solution is usually about 0.01 to 1 part by mass per 100 parts by mass of water, and the potassium iodide content is usually about 0.5 to 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ℃. The immersion time (dyeing time) in the aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, in the case of using a dichroic organic dye as a dichroic dye, a method of immersing a PVA-based film in an aqueous solution containing a water-soluble dichroic organic dye to dye is generally employed. The content of the dichroic organic dye in the aqueous solution is usually about 0.0001 to 10 parts by mass, preferably 0.001 to 1 part by mass, relative to 100 parts by mass of water. The aqueous dye solution may contain an inorganic salt such as sodium sulfate as a dyeing auxiliary. The temperature of the aqueous dichroic organic dye solution used for dyeing is usually about 20 to 80 ℃. The immersion time (dyeing time) in the aqueous solution is usually about 10 to 1,800 seconds.

The boric acid treatment after dyeing with the dichroic dye can be performed by a method of immersing the dyed PVA-based film in an aqueous solution containing boric acid. The boric acid content of the aqueous solution containing boric acid is usually about 2 to 15 parts by mass, preferably 5 to 12 parts by mass, relative to 100 parts by mass of water. In the case of using iodine as the dichroic dye, the aqueous solution containing boric acid preferably contains potassium iodide. The content of potassium iodide in the aqueous solution containing boric acid is usually about 0.1 to 15 parts by mass, preferably 5 to 12 parts by mass, relative to 100 parts by mass of water. The immersion time in the aqueous solution containing boric acid is usually about 60 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the aqueous solution containing boric acid is usually 50℃or higher, preferably 50 to 85℃and more preferably 60 to 80 ℃.

The PVA film after boric acid treatment is usually subjected to a water washing treatment. The water-washing treatment can be performed, for example, by immersing the boric acid-treated PVA-based film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ℃. The immersion time is usually about 1 to 120 seconds.

After washing with water, drying treatment was performed to obtain a polarizing plate. The drying treatment may be performed using a hot air dryer or a far infrared heater. The drying treatment temperature is usually about 30 to 100 ℃, preferably 50 to 80 ℃. The drying time is usually about 60 to 600 seconds, preferably 120 to 600 seconds. The moisture content in the polarizing plate is reduced to a practical level by the drying treatment. The water content is usually about 5 to 20 mass%, preferably 8 to 15 mass% relative to the total mass of the polarizer. If the moisture content is 5 mass% or more, the polarizer has sufficient flexibility, and therefore damage or breakage after drying can be suppressed. In addition, if the moisture content is 20 mass% or less, the polarizing plate has sufficient thermal stability.

As described above, a polarizing plate in which a dichroic dye is adsorbed and oriented on a PVA-based film can be produced.

The visibility correction polarization degree Py of the polarizing plate is usually 95% or more, preferably 97% or more, more preferably 98% or more, still more preferably 98.7% or more, still more preferably 99.0% or more, particularly preferably 99.4% or more, and may be 99.9% or more. The visibility correction polarization degree Py of the polarizing plate may be 99.99% or less. The visibility correction polarization degree Py can be calculated by correcting the visibility of the obtained polarization degree by using a spectrophotometer (V7100 manufactured by japan spectroscopy) with an integrating sphere, using a 2-degree field of view (C light source) of "JIS Z8701".

Improving the visibility correction polarization Py of the polarizing plate is advantageous in improving the function of the optical laminate as an antireflection film and the durability of the optical laminate. If the visibility correction polarization Py of the polarizing plate is less than 95%, the function as an antireflection film may not be exhibited.

The visibility correction monomer transmittance Ty of the polarizing plate is usually 45% or less, and is preferably 44% or less, more preferably 43% or less, from the viewpoint of suppressing the amount of change in the visibility correction polarization Py in a hot and humid environment. The visibility correction monomer transmittance Ty may be set within the above range by adjusting manufacturing conditions such as temperature and time in the step of adsorbing the dichroic dye by dyeing with the dichroic dye.

The boron content of the polarizing plate is preferably 0.5 mass% or more, more preferably 1.5 mass% or more, further preferably 2.5 mass% or more, and particularly preferably 3.0 mass% or more. When the boron content is 0.5 mass% or more, the dichroic dye can be stably held, and the effect of suppressing the decrease in the polarization degree of the polarizing plate and the effect of improving the durability of the optical laminate can be expected. The boron content of the polarizing plate is preferably 5.5 mass% or less, more preferably 5.0 mass% or less, further preferably 4.5 mass% or less, and particularly preferably 4.0 mass% or less. If the boron content is within this range, warpage of the optical laminate and the optical laminate with the adhesive layer can be more effectively suppressed.

The boron content in the polarizer can be determined, for example, by dissolving a polarizer of a predetermined mass in, for example, an aqueous mannitol solution and titrating with an aqueous NaOH solution. The method for measuring the boron content of the polarizing plate is described in detail in one example.

The boron content of the polarizing plate can be controlled by adjusting the boric acid concentration of the aqueous boric acid solution used in the boric acid treatment, the degree of washing with the aqueous boric acid solution in the washing step, and the like.

The thickness T1 of the polarizing plate is 15 μm or less, preferably 13 μm or less, and more preferably 10 μm or less. If the thickness T1 of the polarizing plate is within this range, the thickness of the optical laminate and the optical laminate with an adhesive layer can be reduced, and warping of the optical laminate and the optical laminate with an adhesive layer can be suppressed more effectively. The thickness T1 of the polarizing plate is usually not less than 2. Mu.m, preferably not less than 3. Mu.m, for example, not less than 5. Mu.m.

(3) Protective film

The protective film 20 has a function of protecting the surface of the polarizing plate 10. The protective film 20 may be laminated in direct contact with the surface of the polarizing plate 10, or may be laminated via the 1 st adhesive layer 41 in order to improve the adhesion between the protective film 20 and the polarizing plate 10. In order to improve the adhesion to the polarizing plate 10, the protective film 20 may be subjected to a surface treatment (for example, corona treatment or the like), or a thin layer such as an undercoat layer (also referred to as an easy-to-adhere layer) may be formed.

The protective film 20 satisfies the following formulas (i) and (ii) when the tensile elastic modulus at a temperature of 85 ℃ is E [ MPa ] and the thickness is T2[ mu ] m.

E×T2≤8000 (i)

T2≤7 (ii)

According to the optical laminate and the adhesive layer-attached optical laminate of the present invention satisfying the formulas (i) and (ii), warpage can be suppressed. Further, by disposing the protective film 20 between the polarizing plate 10 and the phase element 30, diffusion of the dichroic dye such as iodine in the polarizing plate 10 out of the optical laminate can be prevented or suppressed. By preventing or suppressing diffusion of a dichroic dye such as iodine, corrosion of a metal member (electrode or the like) existing in the vicinity of the optical laminate in the image display device can be prevented or suppressed.

From the viewpoint of suppressing warpage, the value of the left e×t2 in the formula (i) is preferably 6000 or less. From the viewpoint of suppressing cracks caused by thermal shock, the value of the left e×t2 in the formula (i) is preferably 4000 or less, more preferably 3000 or less, still more preferably 2000 or less, and may be 1850 or 1800 or less. The value of e×t2 is usually 100 or more, and may be 300 or more or 500 or more.

From the viewpoint of suppressing warpage, the thickness T2 of the protective film is preferably 6 μm or less, more preferably 5 μm or less, and further preferably 4 μm or less. From the viewpoint of more effectively suppressing warpage, the thickness T2 is preferably 0.1 μm or more, 0.5 μm or more, 1 μm or more, or 2 μm or more.

From the viewpoint of suppressing cracking caused by thermal shock, the tensile elastic modulus E of the protective film at a temperature of 85 ℃ is preferably 1500MPa or less, more preferably 1200MPa or less, still more preferably 1000MPa or less, particularly preferably 800MPa or less, and most preferably 500MPa or less. The tensile elastic modulus E is usually 100MPa or more and may be 200MPa or more. The tensile elastic modulus E can be measured according to the description of the item [ example ].

As the protective film, for example, a resin film excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, stretchability, and the like can be used. The resin film may be a thermoplastic resin film. Specific examples of such thermoplastic resins include:

Cellulose ester resins such as triacetyl cellulose;

Polyester resins such as polyethylene terephthalate and polyethylene naphthalate;

polyether sulfone resin;

Polysulfone-based resin;

A polycarbonate resin;

polyamide resins such as nylon and aromatic polyamide;

Polyimide resin;

a chain polyolefin resin such as polyethylene, polypropylene, ethylene-propylene copolymer, etc.;

Cyclic polyolefin resins having a ring system and a norbornene structure (also referred to as norbornene resins);

A (meth) acrylic resin such as polymethyl methacrylate;

polyarylate-based resins;

A polystyrene resin;

A polyvinyl alcohol-based resin, wherein the polyvinyl alcohol-based resin,

And mixtures thereof.

Protective films comprising the above thermoplastic resins are commercially available.

The chain polyolefin resin includes a copolymer containing 2 or more chain olefins, in addition to a homopolymer of a chain olefin such as a polyethylene resin (polyethylene resin which is a homopolymer of ethylene, and a copolymer mainly composed of ethylene) or a polypropylene resin (polypropylene resin which is a homopolymer of propylene, and a copolymer mainly composed of propylene).

The cyclic polyolefin resin is a general term for a resin polymerized by using a cyclic olefin as a polymerization unit, and examples thereof include resins described in JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Examples of the cyclic polyolefin resin include a ring-opened (co) polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a copolymer (typically, a random copolymer) of a cyclic olefin and a chain olefin such as ethylene or propylene, a graft polymer obtained by modifying the copolymer with an unsaturated carboxylic acid or a derivative thereof, and a hydrogenated product thereof. Among them, norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers as cyclic olefins are preferably used.

The polyester resin is a resin having an ester bond in the main chain, and is usually a polycondensate of a polycarboxylic acid or a derivative thereof and a polyhydric alcohol. As the polycarboxylic acid or derivative thereof, a 2-membered dicarboxylic acid or derivative thereof may be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, dimethyl naphthalate, and the like. As the polyhydric alcohol, a dibasic diol may be used, and examples thereof include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, cyclohexanedimethanol, and the like. As a representative example of the polyester resin, polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol, is given.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, there are also polymers having a plurality of copolymers constituting the polymerization unit of these cellulose ester resins, and a part of the hydroxyl groups being modified with other substituents. Among them, cellulose triacetate (triacetyl cellulose) is particularly preferable.

The (meth) acrylic resin is a resin mainly composed of a compound having a (meth) acryloyl group. Specific examples of the (meth) acrylic resin include poly (meth) acrylates such as polymethyl methacrylate; methyl methacrylate- (meth) acrylic acid copolymer; methyl methacrylate- (meth) acrylate copolymers; methyl methacrylate-acrylate- (meth) acrylic acid copolymers; methyl (meth) acrylate-styrene copolymer (MS resin, etc.); copolymers of methyl methacrylate and compounds having alicyclic hydrocarbon groups (e.g., methyl methacrylate-cyclohexyl methacrylate copolymers, methyl methacrylate- (meth) norbornyl acrylate copolymers, etc.). Preferably, a polymer containing a poly (C1-C6-alkyl (meth) acrylate such as poly (methyl (meth) acrylate) as a main component is used, and more preferably, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by mass, preferably 70 to 100% by mass) is used.

The polycarbonate resin includes a polymer having a monomer unit bonded thereto via a carbonate group. The polycarbonate resin may be a resin called a modified polycarbonate, a copolycarbonate, or the like, in which the polymer skeleton is modified.

The thermoplastic resin film used as the protective film is preferably a cyclic polyolefin resin film, a polyester resin film, a polycarbonate resin film, a (meth) acrylic resin film, more preferably a cyclic polyolefin resin film, and still more preferably a cyclic polyolefin resin film.

The thermoplastic resin film used as the protective film may be a film in which a monomer is present, and in this case, the thermoplastic resin film is laminated on the polarizing plate 10 via the 1 st adhesive layer 41 as needed. Or the protective film may be a thermoplastic resin layer. For example, a thermoplastic resin layer as a protective film can be laminated on the polarizing plate 10 by applying a composition containing a thermoplastic resin to a support substrate, if necessary, drying the composition to obtain a thermoplastic resin layer with a support substrate, bonding the thermoplastic resin layer with a support substrate to the polarizing plate 10 via the 1 st adhesive layer 41 if necessary, and then peeling off the support substrate.

The protective film may be a cured resin layer containing a cured product of a cured resin. Examples of the curable resin include thermosetting resins and active energy curable resins, and examples thereof include (meth) acrylic resins, epoxy resins, oxetane resins, urethane resins, (meth) acrylic urethane resins, and melamine resins. The cured resin layer containing a cured product of the curable resin may be formed by applying a composition containing the curable resin to a support substrate, drying the composition as necessary, and then heating or radiating active energy rays such as visible light, ultraviolet rays, infrared rays, X-rays, α -rays, β -rays, γ -rays, and electron beams. The obtained cured resin layer with the support base material is bonded to the polarizer 10 via the 1 st adhesive layer 41 as needed, and then the support base material is peeled off, whereby the cured resin layer as a protective film can be laminated on the polarizer 10.

The protective film is preferably a thermoplastic resin film or a thermoplastic resin layer formed of a cyclic polyolefin resin, a thermoplastic resin film or a thermoplastic resin layer formed of a (meth) acrylic resin, or a cured resin layer containing a cured product of a (meth) acrylic resin, from the viewpoint of suppressing warpage of the optical laminate and the optical laminate with an adhesive layer. In order to further suppress diffusion of the dichroic dye in the polarizing plate 10 and further suppress corrosion of the metal member, the protective film is more preferably a thermoplastic resin film or a thermoplastic resin layer formed of a cyclic polyolefin resin.

The protective film may contain any appropriate additive according to the purpose. Examples of the additives include antioxidants such as hindered phenols, phosphorus-based and sulfur-based antioxidants, light stabilizers, ultraviolet absorbers, weather stabilizers and stabilizers such as heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; a near infrared ray absorber; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide, and the like; antistatic agents such as anionic, cationic, and nonionic surfactants; colorants such as inorganic pigments, organic pigments, dyes, and the like; an organic filler and an inorganic filler; a resin modifier; a plasticizer; a lubricant; a phase difference reducing agent, and the like. The kind, combination, content, and the like of the additives contained may be appropriately set according to the purpose, desired characteristics, and the like.

The protective film is preferably a film having no phase difference characteristic or a small phase difference value. Specifically, the in-plane retardation at 550nm of the wavelength of the protective film is preferably 10nm or less. The in-plane phase difference value is more than 0nm. The phase difference in the thickness direction at 550nm of the wavelength of the protective film is preferably-10 nm to +10nm.

(4) Phase element

The phase element 30 is an optical element that exhibits a phase difference in the in-plane or thickness direction, and preferably includes a phase difference film. The retardation film is a film exhibiting a retardation in the in-plane or thickness direction, and is a layer (cured product layer) formed of a polymer of a polymerizable liquid crystal compound, or a combination of the layer and an alignment film. The retardation film includes, for example, a cured layer of a composition for forming a retardation film containing a polymerizable liquid crystal compound.

If the phase element 30 includes a phase difference film, the optical laminate and the optical laminate with an adhesive layer can be thinned, and warpage of the optical laminate and the optical laminate with an adhesive layer can be suppressed more effectively. In addition, from the viewpoint that the wavelength dispersion characteristics can be arbitrarily designed, it is preferable that the phase element 30 include a phase difference film.

(4-1) Phase-difference film

The retardation film is generally formed by applying a composition for forming a retardation film on an alignment film formed on a substrate, and polymerizing a polymerizable liquid crystal compound contained in the composition for forming a retardation film. The retardation film is usually a film obtained by curing a polymerizable liquid crystal compound in an aligned state, and in order to generate a retardation in the observation plane, it is necessary to use a cured film obtained by polymerizing a polymerizable group of the polymerizable liquid crystal compound in a state of being aligned in a horizontal direction with respect to the substrate plane. In this case, the polymerizable liquid crystal compound may be a rod-shaped liquid crystal, or a positive a plate, or a disk-shaped liquid crystal, or a negative a plate.

The phase element may include 2 or more layers of phase difference films having different optical anisotropies. In order to highly realize the antireflection function, it is sufficient to have a λ/4 plate function (i.e., a pi/2 phase difference function) in the entire visible light region. Specifically, a retardation film of 2 or more types having different combinations of orientations is preferable, or a retardation film of a type having inverse wavelength dispersion λ/4 is preferable. For example, a retardation film having a λ/2 plate function (i.e., a retardation function of pi) and a retardation film having a λ/4 plate function (i.e., a retardation function of pi/2) may be combined. In addition, from the viewpoint of being able to compensate for the antireflection function in the oblique direction, it is preferable to further include a layer (positive C plate) having anisotropy in the thickness direction. The respective retardation films may be oriented obliquely or in a cholesteric orientation.

If the in-plane retardation value with respect to light having a wavelength of λnm is set to Re (λ), the λ/4 function in the entire visible light region preferably satisfies the optical characteristics shown by the following formula (1), and preferably satisfies the optical characteristics shown by the following formulas (1), (2) and (3).

100nm＜Re(550)＜160nm (1)

(Wherein Re (550) represents the in-plane retardation value (in-plane retardation) with respect to light having a wavelength of 550 nm.)

Re(450)/Re(550)≤1.0 (2)

1.00≤Re(650)/Re(550) (3)

(Wherein Re (450) represents an in-plane phase difference value with respect to light having a wavelength of 450nm, re (550) represents an in-plane phase difference value with respect to light having a wavelength of 550nm, re (650) represents an in-plane phase difference value with respect to light having a wavelength of 650 nm.)

If the "Re (450)/Re (550)" of the retardation film exceeds 1.0, light leakage on the short wavelength side in the optical laminate provided with the retardation film becomes large. 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, still more preferably 0.80 or more and 0.92 or less, and 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 lamination angle of the plurality of phase difference films, and the phase difference value.

The in-plane retardation value of the retardation film can be adjusted by the thickness of the retardation film. Since the in-plane phase difference value is determined by the following equation (4), Δn (λ) and thickness d may be adjusted to obtain a desired in-plane phase difference value (Re (λ)). The thickness of the retardation film is preferably 0.5 μm to 5 μm, more preferably 1 μm to 3 μm. If the thickness of the retardation film is within the above range, it is advantageous to suppress warpage of the optical laminate and the single sheet of the optical laminate with the adhesive layer. The thickness of the retardation film can be measured by an interferometer, a laser microscope, or a stylus film thickness meter. The Δn (λ) depends on the molecular structure of a polymerizable liquid crystal compound described later.

Re(λ)＝d×Δn(λ) (4)

(Wherein Re (λ) represents an in-plane phase difference value at wavelength λnm, d represents a thickness, and Δn (λ) represents a birefringence at wavelength λnm.)

The positive C plate is not particularly limited as long as it has anisotropy in the thickness direction, and has optical characteristics represented by formula (5) when no tilt alignment or cholesteric alignment is performed.

nx≈ny＜nz (5)

The in-plane phase difference Re (550) at the wavelength of 550nm of the positive C plate is usually in the range of 0 to 10nm, preferably in the range of 0 to 5 nm. The phase difference Rth (550) in the thickness direction at a wavelength of 550nm is usually in the range of-170 nm to-10 nm, preferably-150 nm to-20 nm, more preferably-100 nm to-40 nm. If the phase difference value in the thickness direction is within this range, the antireflection property from the oblique direction can be further improved.

The polymerizable liquid crystal compound contained in the composition for forming a retardation film is a liquid crystal compound having a polymerizable group, particularly a photopolymerizable group, and a conventionally known polymerizable liquid crystal compound can be used as the polymerizable liquid crystal compound. The photopolymerizable group means a group that can participate in polymerization reaction by reactive species generated from a photopolymerization initiator, for example, a living radical, an acid, or the like. Examples of the photopolymerizable group include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, oxiranyl, and oxetanyl groups. Among them, acryloyloxy, methacryloyloxy, ethyleneoxy, ethyleneoxide, and oxetanyl groups are preferable, and acryloyloxy is more preferable. The liquid crystal property may be a thermotropic liquid crystal or a lyotropic liquid crystal, and the thermotropic liquid crystal is preferable in view of being capable of controlling the film thickness in a compact state. The phase-sequence structure in the thermotropic liquid crystal may be a nematic liquid crystal or a smectic liquid crystal. The liquid crystal may be a rod-like liquid crystal or a discotic liquid crystal. The polymerizable liquid crystal compound may be used singly or in combination of two or more.

The polymerizable liquid crystal compound is preferably a liquid crystal having a mesogenic structure in a T-shape or H-shape which further has birefringence in a direction perpendicular to the molecular long axis direction from the viewpoint of exhibiting inverse wavelength dispersion, and is more preferably a T-shape liquid crystal from the viewpoint of obtaining stronger dispersion, and specifically, for example, a compound represented by the following formula (I) is given as a structure of the T-shape liquid crystal.

[ Chemical formula 1]

In the formula (I), ar represents a divalent aromatic group which may have a substituent. The divalent aromatic group preferably contains at least 1 or more of a nitrogen atom, an oxygen atom, and a sulfur atom. When the number of aromatic groups contained in the divalent group Ar is 2 or more, 2 or more aromatic groups may be bonded to each other through a divalent bonding group such as a single bond, -CO-O-, -O-.

G ¹ and G ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group. The hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group or a nitro group, and the carbon atoms constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom or a nitrogen atom.

L ¹、L²、B¹ and B ² are each independently a single bond or a divalent linking group.

K. l each independently represents an integer of 0 to 3, satisfying the relation 1.ltoreq.k+l. Here, in the case where 2.ltoreq.k+l, B ¹ and B ²、G¹ and G ² may be the same as or different from each other, respectively.

E ¹ and E ² each independently represent an alkanediyl group having 1 to 17 carbon atoms, wherein hydrogen atoms contained in the alkanediyl group may be substituted with halogen atoms, the-CH ₂ -contained in the alkanediyl group may be replaced by-O-, -a substitution of S-, -COO-, -S-, -a substitution of the COO-group. P ¹ and P ² each independently represent a polymerizable group or a hydrogen atom, and at least 1 is a polymerizable group.

Each of G ¹ and G ² is independently preferably a1, 4-phenylenediyl group which may be substituted with at least 1 substituent selected from a halogen atom and an alkyl group having 1 to 4 carbon atoms, a1, 4-cyclohexanediyl group which may be substituted with at least 1 substituent selected from a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably a1, 4-phenylenediyl group substituted with a methyl group, an unsubstituted 1, 4-phenylenediyl group, or an unsubstituted 1, 4-trans-cyclohexanediyl group, particularly preferably an unsubstituted 1, 4-phenylenediyl group, or an unsubstituted 1, 4-trans-cyclohexanediyl group.

It is preferable that at least 1 of G ¹ and G ² in the plurality of groups is a divalent alicyclic hydrocarbon group, and it is more preferable that at least 1 of G ¹ and G ² bonded to L ¹ or L ² is a divalent alicyclic hydrocarbon group.

L ¹ and L ² are each independently preferably a single bond, an alkylene group 、-O-、-S-、-R^a1OR^a2-、-R^a3COOR^a4-、-R^a5OCOR^a6-、R^a7OC＝OOR^a8-、-N＝N-、-CR^c＝CR^d-、 having 1 to 4 carbon atoms or-C.ident.C-. Here, R ^a1～R^a8 each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms, and R ^c and R ^d each 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-、-CH₂-、-CH₂CH₂-、-COOR^a4-1 -, OR OCOR ^a6-1 -. Here, R ^a2-1、R^a4-1、R^a6-1 each independently represents any one of a single bond, -CH ₂-、-CH₂CH₂ -. L ¹ and L ² are each independently further preferably a single bond, -O-, -CH ₂CH₂-、-COO-、-COOCH₂CH₂ -, or OCO-.

B ¹ and B ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, a-O-, -S-, -R ^a9OR^a10-、-R^a11COOR^a12-、-R^a13OCOR^a14 -, or R ^a15OC＝OOR^a16 -. Here, R ^a9～R^a16 each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms. More preferably, each of B ¹ and B ² is independently a single bond, -OR ^a10-1-、-CH₂-、-CH₂CH₂-、-COOR^a12 ^-1 -, OR OCOR ^a14-1 -. Here, R ^a10-1、R^a12-1、R^a14-1 each independently represents any one of a single bond, -CH ₂-、-CH₂CH₂ -. B ¹ and B ² are each independently further preferably a single bond, -O-, -CH ₂CH₂-、-COO-、-COOCH₂CH₂ -, -OCO-, or OCOCH ₂CH₂ -.

From the viewpoint of exhibiting inverse wavelength dispersion, k and l are preferably in the range of 2.ltoreq.k+l.ltoreq.6, preferably k+l=4, more preferably k=2 and l=2. K=2 and l=2 are preferable because they have a symmetrical structure.

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 an epoxy group, a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, acryloyloxy, methacryloyloxy, ethyleneoxy, ethyleneoxide, and oxetanyl groups are preferable, and acryloyloxy is more preferable.

Ar preferably has at least one selected from the group consisting of an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocyclic ring which may have a substituent, and an electron withdrawing group. Examples of the aromatic hydrocarbon ring include benzene ring, naphthalene ring, and anthracene ring, and benzene ring and naphthalene ring are preferable. Examples of the aromatic heterocyclic ring include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Among them, a thiazole ring, a benzothiazole ring or a benzofuran ring is preferable, and a benzothiazolyl group is more preferable. In addition, in the case where a nitrogen atom is contained in Ar, the nitrogen atom preferably has pi electrons.

In the formula (I), the total number N _π of pi electrons contained in the 2-valent aromatic group represented by Ar is preferably 8 or more, more preferably 10 or more, still more preferably 14 or more, and particularly preferably 16 or more. The content is preferably 30 or less, more preferably 26 or less, and even more preferably 24 or less.

Examples of the aromatic group represented by Ar include the following groups.

[ Chemical formula 2]

In the formulae (Ar-1) to (Ar-23), the symbols represent a linking moiety, and Z ⁰、Z¹ and Z ² each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an 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-alkylsulfonyl group having 1 to 12 carbon atoms, or an N, N-dialkylsulfamoyl group having 2 to 12 carbon atoms.

Q ¹、Q² 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、Y² and Y ³ each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may be substituted.

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

Examples of the aromatic hydrocarbon group in Y ¹、Y² and Y ³ include aromatic hydrocarbon groups having 6 to 20 carbon atoms such as phenyl, naphthyl, anthryl, phenanthryl, and biphenyl, and preferably phenyl and naphthyl, and more preferably phenyl. Examples of the aromatic heterocyclic group include an aromatic heterocyclic group having 4 to 20 carbon atoms and containing at least 1 hetero atom such as a nitrogen atom, an oxygen atom, a sulfur atom, etc., such as a furyl group, a pyrrolyl group, a thienyl group, a pyridyl group, a thiazolyl group, a benzothiazolyl group, etc., and a furyl group, a thienyl group, a pyridyl group, a thiazolyl group, a benzothiazolyl group are preferable.

Y ¹、Y² and Y ³ each independently may be a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group which may be substituted. Polycyclic aromatic hydrocarbon groups refer to fused polycyclic aromatic hydrocarbon groups or groups derived from an aromatic ring set. Polycyclic aromatic heterocyclic groups refer to fused polycyclic aromatic heterocyclic groups, or groups derived from an aromatic ring set.

Z ⁰、Z¹ 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, an alkoxy group having 1 to 12 carbon atoms, Z ⁰ is more preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, 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、Q² and Q ³ are preferably-NH-, -S-, -NR ^2'-、-O-,R^2' are preferably hydrogen atoms. Wherein, the method comprises the steps of, particularly preferred are-S-, -O-, -NH-.

Of the formulae (Ar-1) to (Ar-23), the formulae (Ar-6) and (Ar-7) are preferable from the viewpoint of stability of the molecule.

In the formulae (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 aromatic heterocyclic groups which may be contained in Ar and are described above, and examples thereof include pyrrole rings, imidazole rings, pyrroline rings, pyridine rings, pyrazine rings, pyrimidine rings, indole rings, quinoline rings, isoquinoline rings, purine rings, pyrrolidine rings, and the like. The aromatic heterocyclic group may have a substituent. Further, Y ¹ may be the above-mentioned polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group which may be substituted together with the nitrogen atom to which Y ¹ is bonded and Z ⁰. Examples thereof include a benzofuran ring, a benzothiazole ring, and a benzoxazole ring.

Among the polymerizable liquid crystal compounds, compounds having a maximum absorption wavelength of 300 to 400nm are preferable. When the photopolymerization initiator is contained in the polymerizable liquid crystal composition, there is a possibility that the polymerization reaction and gelation of the polymerizable liquid crystal compound proceed during long-term storage. However, if the maximum absorption wavelength of the polymerizable liquid crystal compound is 300 to 400nm, the generation of reactive species derived from the photopolymerization initiator and the progress of polymerization and gelation of the polymerizable liquid crystal compound due to the reactive species can be effectively suppressed even when exposed to ultraviolet light during storage. Therefore, the polymerizable liquid crystal composition is advantageous in terms of long-term stability, and the alignment property and uniformity of film thickness of the obtained retardation film can be improved. 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 capable of dissolving the polymerizable liquid crystal compound, and examples thereof include chloroform.

Examples of the discotic polymerizable liquid crystal compound include a compound containing a group represented by the formula (W) (hereinafter, also referred to as "polymerizable liquid crystal compound (W)").

[ Chemical formula 3]

In the formula (W), R ⁴⁰ represents the following formulas (W-1) to (W-5). ]

[ Chemical formula 4]

[ In the formulae (W-1) to (W-5),

X ⁴⁰ and Z ⁴⁰ each independently represent an alkanediyl group having 1 to 12 carbon atoms, wherein hydrogen atoms contained in the alkanediyl group are substituted with an alkoxy group having 1 to 5 carbon atoms, and wherein hydrogen atoms contained in the alkoxy group are substituted with a halogen atom. In addition, in the case of the optical fiber, -CH ₂ forming the alkanediyl group may be substituted by-O-or-CO-.

M2 represents an integer. ]

Examples of the rod-shaped polymerizable liquid crystal compound include compounds represented by the formula (II), the formula (III), the formula (IV), the formula (V), the formula (VI) and the formula (VII).

P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-B16-E12-B17-P12 (II)

P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-F11 (III)

P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-E12-B17-P12 (IV)

P11-B11-E11-B12-A11-B13-A12-B14-A13-F11 (V)

P11-B11-E11-B12-A11-B13-A12-B14-E12-B17-P12 (VI)

P11-B11-E11-B12-A11-B13-A12-F11 (VII)

[ In the formulae (II) to (VII),

A11 to A14 each independently represent a 2-valent alicyclic hydrocarbon group or a 2-valent aromatic hydrocarbon group. The hydrogen atoms contained in the 2-valent alicyclic hydrocarbon group and the 2-valent aromatic hydrocarbon group may be substituted with halogen atoms, alkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, cyano groups, or nitro groups, and the hydrogen atoms contained in the alkyl groups having 1 to 6 carbon atoms and the alkoxy groups having 1 to 6 carbon atoms may be substituted with fluorine atoms.

B11 and B17 each independently represent-O-, -S-, -CO-O-, -O-CO-, -O-CO-O-, -CO-NR ¹⁶-、-NR¹⁶ -CO-, -CS-, or a single bond. R ¹⁶ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

B12 to B16 each independently represents -C≡C-、-CH＝CH-、-CH₂-CH₂-、-O-、-S-、-C(＝O)-、-C(＝O)-O-、-O-C(＝O)-、-O-C(＝O)-O-、-CH＝N-、-N＝CH-、-N＝N-、-C(＝O)-NR¹⁶-、-NR¹⁶-C(＝O)-、-OCH₂-、-OCF₂-、-CH₂O-、-CF₂O-、-CH＝CH-C(＝O)-O-、-O-C(＝O)-CH＝CH- or a single bond.

E11 and E12 each independently represent an alkanediyl group having 1 to 12 carbon atoms, wherein hydrogen atoms contained in the alkanediyl group are optionally substituted by alkoxy groups having 1 to 5 carbon atoms, and wherein hydrogen atoms contained in the alkoxy groups are optionally substituted by halogen atoms. In addition, in the case of the optical fiber, -CH ₂ forming the alkanediyl group may be substituted by-O-or-CO-.

F11 represents a hydrogen atom, an alkyl group having 1 to 13 carbon atoms, an alkoxy group having 1 to 13 carbon atoms, a cyano group, a nitro group, a trifluoromethyl group, a dimethylamino group, a hydroxyl group, a hydroxymethyl group, a formyl group, a sulfo group (-SO ₃ H), a carboxyl group, an alkoxycarbonyl group having 1 to 10 carbon atoms or a halogen atom, and-CH ₂ -constituting the alkyl group and the alkoxy group may be substituted with-O-.

P11 and P12 each independently represent a polymerizable group. ]

The content of the polymerizable liquid crystal compound in the composition for forming a phase difference film is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, more preferably 85 to 98 parts by mass, and even more preferably 90 to 95 parts by mass, relative to 100 parts by mass of the solid content of the composition for forming a phase difference film. If the content of the polymerizable liquid crystal compound is within the above range, it is advantageous from the viewpoint of the orientation of the obtained retardation film. In the present specification, the solid content of the polymerizable liquid crystal composition means all components obtained by removing volatile components such as an organic solvent from the polymerizable liquid crystal composition.

(4-2) Composition for Forming a phase-difference film

As described above, the composition for forming a retardation film contains a polymerizable liquid crystal compound. The composition for forming a retardation film may further contain a solvent, a leveling agent, a polymerization initiator, a photosensitizer, a polymerization inhibitor, a crosslinking agent, a thickener, and other reactive additives, and from the viewpoint of processability, the composition preferably contains a solvent and a leveling agent.

The composition for forming a retardation film may contain a solvent. In general, since the viscosity of the polymerizable liquid crystal compound is high, the composition for forming a retardation film is prepared by dissolving the composition in a solvent, and thus coating becomes easy, and as a result, the formation of a retardation film becomes easy in many cases. The solvent is preferably a solvent capable of completely dissolving the polymerizable liquid crystal compound, and is preferably a solvent inactive to the polymerization reaction of the polymerizable liquid crystal compound.

Examples of the solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, gamma-butyrolactone or propylene glycol methyl ether acetate, ethyl lactate and other ester solvents; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; aromatic hydrocarbon solvents such as toluene and xylene, nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and 1, 3-dimethyl-2-imidazolidinone. These solvents may be used alone or in combination of 2 or more.

The content of the solvent is preferably 50 to 98% by mass relative to the total amount of the composition for forming a retardation film. In other words, the content of the solid component in the composition for forming a phase difference film is preferably 2 to 50% by mass, more preferably 5 to 30% by mass. If the content of the solid component is 50 mass% or less, the viscosity of the composition for forming a retardation film becomes low, and thus the thickness of the retardation film becomes substantially uniform, and the retardation film tends to be less likely to be uneven. The solid content can be determined in consideration of the thickness of the retardation film to be produced.

The composition for forming a retardation film may contain a leveling agent. The leveling agent is an additive having a function of adjusting the fluidity of the composition and flattening a film obtained by coating the composition, and examples thereof include organosilicon-modified, polyacrylate-based, and perfluoroalkyl-based leveling agents. Among them, the polyacrylate-based leveling agent and the perfluoroalkyl-based leveling agent are preferable in the case of performing horizontal alignment, and the organic modified silicone-based leveling agent and the perfluoroalkyl-based leveling agent are preferable in the case of performing vertical alignment.

When the composition for forming a retardation film contains a leveling agent, the content thereof is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, relative to 100 parts by mass of the content of the polymerizable liquid crystal compound. If the content of the leveling agent is within the above range, the polymerizable liquid crystal compound is easily oriented horizontally, and the obtained retardation film tends to become smoother. If the content of the leveling agent in the polymerizable liquid crystal compound exceeds the above range, the obtained retardation film tends to be uneven. The composition for forming a retardation film may contain 2 or more leveling agents.

The composition for forming a retardation film may contain a polymerization initiator. The polymerization initiator is a compound capable of initiating a polymerization reaction of a polymerizable liquid crystal compound or the like. As the polymerization initiator, a photopolymerization initiator that generates living radicals by the action of light is preferable from the standpoint of not depending on the phase state of the thermotropic liquid crystal.

The photopolymerization initiator may be any known photopolymerization initiator as long as it is a compound capable of initiating polymerization reaction of the polymerizable liquid crystal compound. Specifically, a photopolymerization initiator capable of generating a living radical or an acid by the action of light is exemplified, and among them, a photopolymerization initiator capable of generating a radical by the action of light is preferable. The photopolymerization initiator may be used singly or in combination of two or more.

As the photopolymerization initiator, a known photopolymerization initiator can be used, and as the photopolymerization initiator generating active radicals, for example, a self-cleaving benzoin compound, acetophenone compound, hydroxyacetophenone compound, α -aminoacetophenone compound, oxime ester compound, acylphosphine oxide compound, azo compound, etc., a hydrogen abstraction benzophenone compound, alkylbenzene ketone compound, benzoin ether compound, benzil ketal compound, dibenzosuberone compound, anthraquinone compound, xanthone compound, thioxanthone compound, haloacetophenone compound, dialkoxyacetophenone compound, halobisimidazole compound, halotriazine compound, triazine compound, etc. can be used. As the photopolymerization initiator for generating an acid, iodonium salts, sulfonium salts, and the like can be used. From the viewpoint of excellent reaction efficiency at low temperatures, a photopolymerization initiator is preferable, and acetophenone-based compounds, hydroxyacetophenone-based compounds, α -aminoacetophenone-based compounds, and oxime ester-based compounds are particularly preferable.

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

The composition for forming a retardation film may contain a sensitizer. As the sensitizer, a photosensitizer is preferable. Examples of the sensitizer include xanthone compounds such as xanthone and thioxanthone (e.g., 2, 4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and alkoxy group-containing anthracene (e.g., dibutoxyanthracene); phenothiazine, rubrene, and the like.

When the composition for forming a retardation film contains a sensitizer, the polymerization reaction of the polymerizable liquid crystal compound contained in the composition for forming a retardation film can be further promoted. The sensitizer is used in an amount of preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound.

The composition for forming a retardation film may contain an antioxidant from the viewpoint of stably conducting the polymerization reaction. The degree of progress of the polymerization reaction of the polymerizable liquid crystal compound can be controlled by the antioxidant.

The antioxidant may be, for example, a primary antioxidant selected from the group consisting of a phenol-based antioxidant, an amine-based antioxidant, a quinone-based antioxidant and a nitroso-based antioxidant, or a secondary antioxidant selected from the group consisting of a phosphorus-based antioxidant and a sulfur-based antioxidant.

When the composition for forming a retardation film contains an antioxidant, the content of the antioxidant is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the content of the polymerizable liquid crystal compound. The antioxidant may be used alone or in combination of 2 or more. If the content of the antioxidant is within the above range, polymerization can be performed without disturbing the orientation of the polymerizable liquid crystal compound.

The composition for forming a retardation film may contain a reactive additive. The reactive additive preferably has a carbon-carbon unsaturated bond, an active hydrogen reactive group, and a mercapto group in its molecule. The "active hydrogen-reactive group" as used herein refers to a group reactive with a group having an active hydrogen such as a carboxyl group (-COOH), a hydroxyl group (-OH), an amino group (-NH ₂), and the like, and is exemplified by a glycidyl group, an oxazoline group, a carbodiimide group, an aziridine group, an imide group, an isocyanate group, a thioisocyanate group, a maleic anhydride group, and the like. The number of reactive groups contained in the reactive additive is usually 1 to 20, preferably 1 to 10.

(4-3) Substrate

As the above-mentioned substrate for forming the retardation film, a glass substrate and a film substrate are exemplified, and a film substrate is preferable, and a long roll film is more preferable in view of continuous production. Examples of the resin constituting the film base material include chain polyolefins such as polyethylene and polypropylene; a cyclic olefin resin; polyvinyl alcohol; polyethylene terephthalate; a polymethacrylate; a polyacrylate; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; a polycarbonate; polysulfone; polyether sulfone; polyether ketone; polyphenylene sulfide, polyphenylene oxide, and the like. Among them, from the viewpoint of transparency and the like when used in the optical film application, a film base material selected from any one of triacetyl cellulose, a cycloolefin resin, a polymethacrylate, and polyethylene terephthalate is more preferable.

As a commercially available cellulose ester substrate, "FUJITAC FILM" (manufactured by Fuji Photo FILM Co., ltd.); "KC8UX2M", "KC8UY" and "KC4UY" (manufactured by Konica Minolta Opto Co., ltd.) and the like.

Examples of commercially available cycloolefin resins include "Topas" (registered trademark) (manufactured by Ticona corporation (germany)), "ARTON" (registered trademark) (manufactured by JSR corporation), "ZEONOR" (registered trademark), and "ZEONEX" (registered trademark) (manufactured by ZEONEX corporation) and "APEL" (registered trademark) (manufactured by mitsunk chemical corporation). Such a cycloolefin resin can be formed into a substrate by a known method such as a solvent casting method or a melt extrusion method. Commercially available cycloolefin resin base materials can also be used. Examples of commercially available cycloolefin resin substrates include "Esushina" (registered trademark), "SCA40" (registered trademark) (the above are available from Seattle chemical Co., ltd.), "ZeonorFilm" (registered trademark) (available from Optes Co., ltd.), and "Arton Film" (registered trademark) (available from JSR Co., ltd.).

The thickness of the base material is preferably thin enough to enable practical handling, but if too thin, the strength tends to be low and the workability tends to be poor. The thickness of the substrate is usually 5 μm to 300. Mu.m, preferably 10 μm to 200. Mu.m, more preferably 10 μm to 50. Mu.m. Further, the retardation film is peeled off from the substrate and transferred, whereby a further film-forming effect can be obtained.

(4-4) Orientation film

In the present specification, the alignment film has an alignment regulating force for aligning the polymerizable liquid crystal compound in a desired direction.

The alignment film facilitates liquid crystal alignment of the polymerizable liquid crystal compound. The state of liquid crystal alignment such as horizontal alignment, vertical alignment, hybrid alignment, tilt alignment, etc. varies depending on the properties of the alignment film and the polymerizable liquid crystal compound, and the combination thereof may be arbitrarily selected. For example, if the alignment film is a material exhibiting horizontal alignment as an alignment regulating force, the polymerizable liquid crystal compound can be aligned horizontally or hybrid, and if it is a material exhibiting vertical alignment, the polymerizable liquid crystal compound can be aligned vertically or obliquely. The expressions horizontal, vertical, etc. refer to the direction of the optical axis of the oriented polymerizable liquid crystal compound when the retardation film plane is taken as a reference. For example, vertical alignment refers to having the optical axis of the polymerizable liquid crystal compound aligned in a direction perpendicular to the plane of the phase difference film. The term "perpendicular" as used herein means 90±20° with respect to the plane of the retardation film.

The orientation regulating force may be arbitrarily adjusted according to the surface state and rubbing condition in the case where the orientation film is formed of an orientation polymer, and may be arbitrarily adjusted according to the polarized light irradiation condition in the case where the orientation film is formed of a photo-orientation polymer. In addition, the liquid crystal orientation may be controlled by selecting physical properties such as surface tension and liquid crystallinity of the polymerizable liquid crystal compound.

As the alignment film formed between the base material and the retardation film, an alignment film which is insoluble in a solvent used when the retardation film is formed on the alignment film and has heat resistance in a heating process for removing the solvent and aligning the liquid crystal is preferable. As the alignment film, an alignment film containing an alignment polymer, a photo-alignment film and a groove (groove) alignment film, a stretched film stretched in the alignment direction, and the like are exemplified, and in the case of being applied to a long roll film, a photo-alignment film is preferable in view of being able to easily control the alignment direction.

The thickness of the alignment film is usually in the range of 10nm to 5000nm, preferably in the range of 10nm to 1000nm, more preferably in the range of 30 to 300nm.

Examples of the alignment polymer used for the rubbing alignment film include polyamide having an amide bond in the molecule, gelatin, polyimide having an imide bond in the molecule, polyamic acid as a hydrolysate thereof, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethylenimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylate. Among them, polyvinyl alcohol is preferable. These alignment polymers may be used alone or in combination of 2 or more.

As a method for performing friction, the following method can be mentioned: the film of the oriented polymer formed on the surface of the substrate by applying the oriented polymer composition to the substrate and annealing is brought into contact with a rotating rubbing roller around which a rubbing cloth is wound.

The photo-alignment film comprises a polymer, oligomer or monomer having a photoreactive group. The photo-alignment film obtains an alignment regulating force by irradiating polarized light. The photo-alignment film is more preferable in that the direction of the alignment regulating force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

Photoreactive groups refer to groups that generate liquid crystal alignment ability by irradiation with light. Specifically, the group is a group that generates a photoreaction that causes the liquid crystal aligning ability, such as an alignment induction or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photodecomposition reaction of a molecule generated by irradiation with light. Among the photoreactive groups, those that undergo dimerization or photocrosslinking are preferred in view of their excellent orientation. As the photoreactive group capable of undergoing the above reaction, a group having an unsaturated bond, particularly a double bond, is preferable, and a group having at least one selected from the group consisting of a carbon-carbon double bond (c=c bond), a carbon-nitrogen double bond (c=n bond), a nitrogen-nitrogen double bond (n=n bond), and a carbon-oxygen double bond (c=o bond) is more preferable.

Examples of the photoreactive group having a c=c bond include a vinyl group, a polyalkenyl group, a stilbene oxazolyl group, a stilbene oxazolium group, a chalcone group, and a cinnamoyl group. From the viewpoint of easy control of reactivity and the viewpoint of orientation restriction force at the time of exhibiting photoalignment, a chalcone group and a cinnamoyl group are preferable. Examples of the photoreactive group having a c=n bond include groups having a structure such as an aromatic schiff base and an aromatic hydrazone. Examples of the photoreactive group having an n=n bond include groups having an azobenzene oxide basic structure such as an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a disazo group, and a formazan group. 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 substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, and haloalkyl.

The polarized light may be irradiated directly from the film surface, or irradiated by irradiating polarized light from the substrate side and transmitting the polarized light. In addition, the polarized light is particularly preferably substantially parallel light. The wavelength of the irradiated polarized light is suitably a wavelength in a wavelength region where the photoreactive group of the polymer or monomer having the photoreactive group is capable of absorbing light energy. Specifically, UV (ultraviolet light) having a wavelength in the range of 250 to 400nm is particularly preferable. Examples of the light source used for the polarized light irradiation include a xenon lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, an ultraviolet laser such as KrF or ArF, and more preferably a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp. These lamps are preferable because of the high luminous intensity of ultraviolet light having a wavelength of 313 nm. The polarized light can be irradiated by irradiating the light from the light source through an appropriate polarizer. As the polarizing plate, a polarizing prism such as a polarizing filter, a gla thomson prism, a gla taylor prism, or a wire grid type polarizing plate can be used.

(5) Adhesive layer

The 1 st pressure-sensitive adhesive layer 41 is a layer provided as needed for bonding the polarizer 10 and the protective film 20. The optical laminate preferably includes the 1 st adhesive layer 41. The 2 nd pressure-sensitive adhesive layer 42 is a layer provided for bonding the protective film 20 to the phase element 30. The optical stack preferably includes a 2 nd adhesive layer 42.

The 1 st adhesive layer 41 and the 2 nd adhesive layer 42 may be adhesive layers or adhesive layers, respectively. The adhesive layer is a layer formed of an adhesive composition (pressure-sensitive adhesive composition), and the adhesive layer is a layer formed of an adhesive composition. The 1 st adhesive layer 41 is preferably an adhesive layer. The 2 nd adhesive layer 42 is preferably an adhesive layer.

(5-1) Adhesive layer

Examples of the adhesive composition for forming the adhesive layer include an aqueous adhesive composition and a curable adhesive composition cured by irradiation of active energy rays such as heat, ultraviolet rays, visible light, electron beams, and X-rays. Examples of the aqueous adhesive composition include a composition obtained by dissolving a polyvinyl alcohol resin or a urethane resin as a main component in water and a composition obtained by dispersing a polyvinyl alcohol resin or a urethane resin as a main component in water. The aqueous adhesive composition may further contain a curable component such as a polyaldehyde, a melamine compound, a zirconia compound, a zinc compound, a glyoxal compound, a water-soluble epoxy resin, and a crosslinking agent. Examples of the aqueous adhesive composition include an adhesive composition described in japanese patent application laid-open publication No. 2010-191389, an adhesive composition described in japanese patent application laid-open publication No. 2011-107686, a composition described in japanese patent application laid-open publication No. 2020-172088, and a composition described in japanese patent application laid-open publication No. 2005-208456.

The curable adhesive composition is preferably an active energy ray curable adhesive composition which contains a curable (polymerizable) compound as a main component and is cured by irradiation with active energy rays. Examples of the active energy ray-curable adhesive composition include a cationic polymerizable adhesive composition containing a cationic polymerizable compound as a curable compound, a radical polymerizable adhesive composition containing a radical polymerizable compound as a curable compound, and a mixed adhesive composition containing both a cationic polymerizable compound and a radical polymerizable compound as a curable compound.

The cationically polymerizable compound is a compound or oligomer which is cured by a cationic polymerization reaction by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, X-rays, and the like, and specifically, an epoxy compound, an oxetane compound, a vinyl compound, and the like are exemplified.

Examples of the epoxy compound include alicyclic epoxy compounds (compounds having 1 or more epoxy groups bonded to an alicyclic ring in the molecule) such as 3, 4-epoxycyclohexane carboxylic acid 3',4' -epoxycyclohexylmethyl ester; aromatic epoxy compounds (compounds having an aromatic ring and an epoxy group in the molecule) such as diglycidyl ether of bisphenol a; aliphatic epoxy compounds such as 2-ethylhexyl glycidyl ether and 1, 4-butanediol diglycidyl ether (compounds having at least 1 oxirane ring bonded to an aliphatic carbon atom in the molecule), and the like.

Examples of oxetane compounds include compounds having 1 or more oxetane rings in the molecule, such as 3-ethyl-3- { [ (3-ethyloxetan-3-yl) methoxy ] methyl } oxetane.

The cationically polymerizable adhesive composition preferably contains a cationic polymerization initiator. The cationic polymerization initiator may be a thermal cationic polymerization initiator or a photo cationic polymerization initiator. Examples of the cationic polymerization initiator include aromatic diazonium salts such as benzodiazonium hexafluoroantimonate; aromatic iodonium salts such as diphenyliodonium tetrakis (pentafluorophenyl) borate; aromatic sulfonium salts such as triphenylsulfonium hexafluorophosphate; iron-arene complexes such as xylene-cyclopentadienyl iron (II) hexafluoroantimonate. The content of the cationic polymerization initiator is usually 0.1 to 10 parts by mass relative to 100 parts by mass of the cationically polymerizable compound. The cationic polymerization initiator may contain 2 or more.

Examples of the cationically polymerizable adhesive composition include those described in JP 2016-126345, international publication No. 2019/10315, and JP 2021-113969.

The radical polymerizable compound is a compound or oligomer which is cured by radical polymerization reaction by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, X-rays, and the like, and specifically, a compound having an ethylenically unsaturated bond is exemplified. Examples of the compound having an ethylenically unsaturated bond include a (meth) acrylic compound having 1 or more (meth) acryloyl groups in the molecule, a vinyl compound having 1 or more vinyl groups in the molecule, and the like.

Examples of the (meth) acrylic compound include (meth) acryl-containing compounds such as (meth) acrylic oligomers having at least 2 (meth) acryl groups in the molecule, which are obtained by reacting 2 or more kinds of (meth) acrylate monomers having at least 1 (meth) acryloyloxy group in the molecule, a (meth) acrylamide monomer, and a functional group-containing compound.

The radical polymerization type adhesive composition preferably contains a radical polymerization initiator. The radical polymerization initiator may be a thermal radical polymerization initiator or a photo radical polymerization initiator. Examples of the radical polymerization initiator include acetophenone-based initiators such as acetophenone and 3-methylacetophenone; benzophenone-based initiators such as benzophenone, 4-chlorobenzophenone and 4,4' -diaminobenzophenone; benzoin ether initiators such as benzoin propyl ether and benzoin diethyl ether; thioxanthone-based initiators such as 4-isopropylthioxanthone; xanthone, fluorenone, and the like. The content of the radical polymerization initiator is usually 0.1 to 10 parts by mass based on 100 parts by mass of the radical polymerizable compound. The radical polymerization initiator may contain 2 or more kinds.

Examples of the radical polymerizable adhesive composition include radical polymerizable compositions described in Japanese patent application laid-open No. 2016-126345, japanese patent application laid-open No. 2016-153474, and International publication No. 2017/183335.

The active energy ray-curable adhesive composition may contain, if necessary, an additive such as an ion scavenger, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, a defoaming agent, an antistatic agent, a leveling agent, a solvent, and the like.

The bonding of the two layers by the adhesive layer can be performed as follows: the adhesive composition is applied to at least one of the bonding surfaces selected from the two layers, the two layers are laminated via the application layer of the adhesive composition, and the two layers are pressed from the top and bottom by a bonding roller or the like to bond the two layers, and then the adhesive layer is dried, cured by irradiation with active energy rays, or cured by heating.

Before forming the coating layer of the adhesive layer, at least one bonding surface selected from the bonding surfaces of the two layers may be subjected to an easy-to-adhere treatment such as saponification treatment, corona treatment, plasma treatment, primer treatment, anchor coating treatment, and the like.

The adhesive composition may be formed by various coating methods such as die coater, comma coater, gravure coater, bar coater, and blade coater.

The light irradiation intensity upon irradiation with the active energy ray is determined according to the composition of each active energy ray-curable adhesive composition, and is not particularly limited, but is preferably 10mW/cm ² or more and 1,000mW/cm ² or less. The irradiation intensity is preferably an intensity in a wavelength region effective for activation of the photo-cationic polymerization initiator or the photo-radical polymerization initiator. The irradiation is preferably performed 1 or more times at such a light irradiation intensity that the cumulative light amount is 10mJ/cm ² or more, more preferably 100mJ/cm ² or more and 1,000mJ/cm ² or less.

The light source used for polymerization curing of the active energy ray-curable adhesive composition is not particularly limited, and examples thereof include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a halogen lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.

The thickness of the adhesive layer formed of the aqueous adhesive composition may be, for example, 5 μm or less, preferably 1 μm or less, more preferably 0.5 μm or less, and may be 0.01 μm or more, preferably 0.05 μm or more.

The thickness of the adhesive layer formed from the active energy ray-curable adhesive composition may be, for example, 10 μm or less, preferably 5 μm or less, more preferably 3 μm or less, and may be 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more.

(5-2) Adhesive layer

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer is not particularly limited, and a pressure-sensitive adhesive composition having excellent optical transparency, which has been known in the related art, for example, a pressure-sensitive adhesive composition having a base polymer such as a (meth) acrylic resin, a urethane resin, a silicone resin, or a polyvinyl ether resin, may be used. The adhesive composition may be an active energy ray-curable adhesive composition, a thermosetting adhesive composition, or the like. Among them, an adhesive composition containing a (meth) acrylic resin excellent in transparency, adhesion, removability, weather resistance, heat resistance and the like as a base polymer is preferable.

The adhesive composition may further comprise a crosslinking agent, a silane compound, an antistatic agent, and the like.

[ (Meth) acrylic resin ]

The (meth) acrylic resin contained in the adhesive composition is preferably a polymer (hereinafter, also referred to as "(meth) acrylate polymer") containing a structural unit derived from an alkyl (meth) acrylate represented by the following formula (VIII) (hereinafter, also referred to as "structural unit (VIII)") as a main component (for example, 50 parts by mass or more per 100 parts by mass of the structural unit of the (meth) acrylic resin).

[ Chemical formula 5]

In the formula (VIII), R ¹⁰ represents a hydrogen atom or a methyl group, R ²⁰ represents an alkyl group having 1 to 20 carbon atoms, the alkyl group may have any of a linear, branched or cyclic structure, and the hydrogen atom of the alkyl group may be substituted with an alkoxy group having 1 to 10 carbon atoms. ]

Examples of the (meth) acrylic acid ester represented by the formula (VIII) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, isohexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, stearyl (meth) acrylate, and t-butyl (meth) acrylate. Specific examples of the alkyl acrylate containing an alkoxy group include 2-methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, and the like. Among them, n-butyl (meth) acrylate or 2-ethylhexyl (meth) acrylate is preferably contained, and n-butyl (meth) acrylate is particularly preferably contained.

The (meth) acrylate polymer may contain structural units derived from monomers other than the structural unit (VIII). The number of structural units derived from other monomers may be 1 or 2 or more. Examples of the other monomer that may be contained in the (meth) acrylate polymer include a monomer having a polar functional group, a monomer having an aromatic group, and a (meth) acrylamide monomer.

Examples of the monomer having a polar functional group include (meth) acrylic esters having a polar functional group. Examples of the polar functional group include a hydroxyl group; a carboxyl group; substituted amino group or unsubstituted amino group substituted with alkyl group having 1 to 6 carbon atoms; heterocyclic groups such as epoxy groups, and the like.

The content of the structural unit derived from the monomer having a polar functional group in the (meth) acrylate polymer is preferably 10 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, still more preferably 0.5 parts by mass or more and 5 parts by mass or less, particularly preferably 1 part by mass or more and 5 parts by mass or less, per 100 parts by mass of the total structural units of the (meth) acrylate polymer.

Examples of the monomer having an aromatic group include (meth) acrylic acid esters having 1 (meth) acryloyl group and 1 or more aromatic rings (for example, benzene ring, naphthalene ring, etc.) in the molecule and having phenyl, phenoxyethyl, or benzyl groups. By including these structural units, the white spot phenomenon of the polarizing plate generated in a high-temperature and high-humidity environment can be suppressed.

The content of the structural unit derived from the monomer having an aromatic group in the (meth) acrylate polymer is preferably 20 parts by mass or less, more preferably 4 parts by mass or more and 20 parts by mass or less, and still more preferably 4 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the total structural units of the (meth) acrylate polymer.

Examples of the (meth) acrylamide monomer include N- (methoxymethyl) (meth) acrylamide, N- (ethoxymethyl) (meth) acrylamide, N- (propoxymethyl) (meth) acrylamide, N- (butoxymethyl) (meth) acrylamide, and N- (2-methylpropoxymethyl) (meth) acrylamide. By including these structural units, bleeding of additives such as an antistatic agent described later can be suppressed.

The structural unit derived from a monomer other than the structural unit (VIII) may include a structural unit derived from a styrene monomer, a structural unit derived from a vinyl monomer, a structural unit derived from a monomer having a plurality of (meth) acryloyl groups in the molecule, and the like.

The weight average molecular weight (hereinafter, also simply referred to as "Mw") of the (meth) acrylic resin is preferably 50 to 250 ten thousand. When the weight average molecular weight is 50 ten thousand or more, the durability of the pressure-sensitive adhesive layer in a high-temperature and high-humidity environment can be improved. When the weight average molecular weight is 250 ten thousand or less, the workability in applying the coating liquid containing the adhesive composition becomes good. The molecular weight distribution (Mw/Mn) shown by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (hereinafter also simply referred to as "Mn") is usually 2 to 10. In the present specification, the "weight average molecular weight" and the "number average molecular weight" are polystyrene equivalent values measured by a Gel Permeation Chromatography (GPC) method.

When the (meth) acrylic resin is dissolved in ethyl acetate to prepare a solution having a concentration of 20% by mass, the viscosity at 25℃is preferably 20 Pa.s or less, more preferably 0.1 to 15 Pa.s. If the viscosity of the (meth) acrylic resin at 25℃is within the above range, the durability and reworkability of the optical laminate including the adhesive layer formed of the resin can be improved. The above viscosity can be measured by a Brookfield viscometer.

The glass transition temperature (Tg) of the (meth) acrylic resin is, for example, -60 to 20 ℃, preferably-50 to 15 ℃, more preferably-45 to 10 ℃, still more preferably-40 to 0 ℃. The glass transition temperature may be measured by a Differential Scanning Calorimeter (DSC).

The (meth) acrylic resin may contain 2 or more (meth) acrylate polymers. The (meth) acrylate polymer may be a (meth) acrylate polymer having a weight average molecular weight and a specific gravity average molecular weight of 50 to 250 tens of thousands of the (meth) acrylate polymer having a small weight average molecular weight, and more specifically, a (meth) acrylate polymer having a structural unit (VIII) derived from a (meth) acrylate as a main component and having a relatively low molecular weight in a range of 5 to 30 tens of thousands of the weight average molecular weight may be mentioned.

The (meth) acrylic resin can be generally produced by a known polymerization method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method. In the production of (meth) acrylic resins, polymerization is generally carried out in the presence of a polymerization initiator. The amount of the polymerization initiator used is usually 0.001 to 5 parts by mass per 100 parts by mass of the total of all the monomers constituting the (meth) acrylic resin. The (meth) acrylic resin can also be produced by a method of polymerization using active energy rays such as ultraviolet rays.

[ Cross-linking agent ]

The adhesive composition preferably comprises a cross-linking agent. The crosslinking agent may be a conventional crosslinking agent (for example, an isocyanate compound, an epoxy compound, an aziridine compound, a metal chelate compound, a peroxide, or the like), and is preferably an isocyanate compound from the viewpoints of pot life of the adhesive composition, crosslinking speed, durability of the optical laminate, and the like.

The isocyanate compound is a compound having at least 2 isocyanate groups (-NCO) in the molecule. Specifically, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, and the like can be mentioned. Further, adducts obtained by reacting these isocyanate compounds with a polyol such as glycerin or trimethylolpropane, dimers and trimers of these isocyanate compounds are also exemplified. It is also possible to combine 2 or more isocyanate compounds.

The proportion of the crosslinking agent is, for example, 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 1 part by mass, relative to 100 parts by mass of the (meth) acrylic resin.

[ Silane Compound ]

The adhesive composition may further contain a silane compound.

Examples of the silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl triethoxysilane, 3-glycidoxypropyl methyldimethoxysilane, 3-glycidoxypropyl ethoxydimethylsilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloxypropyl trimethoxysilane, and 3-mercaptopropyl trimethoxysilane.

In addition, the silane compound may contain an oligomer derived from the above silane compound.

The content of the silane compound in the adhesive composition is usually 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, relative to 100 parts by mass of the (meth) acrylic resin. If the content of the silane compound is 0.01 parts by mass or more, the adhesion between the adhesive layer and the adherend tends to be improved, and if the content is 10 parts by mass or less, the silane compound tends to be inhibited from bleeding out from the adhesive layer.

[ Antistatic agent ]

The adhesive composition may further contain an antistatic agent. As the antistatic agent, known antistatic agents can be used, and ionic antistatic agents are suitable. Examples of the cationic component constituting the ionic antistatic agent include organic cations and inorganic cations. Examples of the organic cation include pyridinium cation, imidazolium cation, ammonium cation, sulfonium cation, and phosphonium cation. Examples of the inorganic cations include alkali metal cations such as lithium cations, potassium cations, sodium cations, cesium cations, etc., alkaline earth metal cations such as magnesium cations, calcium cations, etc. The anionic component constituting the ionic antistatic agent may be any of an inorganic anion and an organic anion, and is preferably an anionic component containing a fluorine atom in view of excellent antistatic performance. Examples of the anion component containing a fluorine atom include hexafluorophosphate anion (PF ₆ ^-), bis (trifluoromethanesulfonyl) imide anion [ (CF ₃SO₂)₂N^- ], bis (fluorosulfonyl) imide anion [ (FSO ₂)₂N^- ], and the like.

From the viewpoint of excellent stability of the antistatic property of the adhesive composition with time, an ionic antistatic agent that is solid at room temperature is preferred.

The content of the antistatic agent is, for example, 0.01 to 20 parts by mass, preferably 0.1 to 10 parts by mass, and more preferably 1 to 7 parts by mass, relative to 100 parts by mass of the (meth) acrylic resin.

The adhesive composition may contain additives such as ultraviolet absorbers, solvents, crosslinking catalysts, tackifying resins (tackifiers), plasticizers, and the like alone or in an amount of 2 or more. Further, it is also useful to prepare a harder adhesive layer by mixing an ultraviolet-curable compound with the adhesive composition to form an adhesive layer and then irradiating the adhesive layer with ultraviolet rays to cure the adhesive layer.

The adhesive layer can be formed, for example, by dissolving or dispersing the above-mentioned adhesive composition in a solvent to prepare an adhesive composition containing the solvent, and then applying the adhesive composition to the surface of the substrate or the layer provided with the adhesive layer and drying the same.

The thickness of the adhesive layer is usually 0.1 to 30. Mu.m, preferably 3 to 30. Mu.m, more preferably 5 to 25. Mu.m.

(6) Adhesive layer

The optical laminate with an adhesive layer includes an adhesive layer 50 laminated on the opposite side of the phase element 30 of the optical laminate from the protective film 20 side. The adhesive layer 50 is described in the above (5-2).

When the storage modulus of the pressure-sensitive adhesive layer 50 at a temperature of 23 ℃ is G' [ MPa ] and the thickness is T3[ mu ] m, the following formula (iii) is preferably satisfied.

G’/T3≤5 (iii)

By satisfying the expression (iii), warpage can be further suppressed.

From the viewpoint of suppressing warpage, the value of the left G'/T3 in the formula (iii) is preferably 1 or less, more preferably 0.030 or less, still more preferably 0.025 or less, still more preferably 0.020 or less, still more preferably 0.010 or less, particularly preferably 0.005 or less, still more preferably 0.002 or less, and most preferably 0.0015 or less. The value of G'/T3 may be 0.0001 or more.

From the viewpoint of suppressing warpage, the storage modulus G' of the pressure-sensitive adhesive layer 50 at a temperature of 23 ℃ is preferably 5MPa or less, more preferably 1MPa or less, further preferably 0.5MPa or less, still more preferably 0.2MPa or less, and particularly preferably 0.1MPa or less. The storage modulus G' is usually 0.001MPa or more and may be 0.01MPa or more. The storage modulus G' can be measured according to the description of the item [ example ].

From the viewpoint of suppressing warpage, the thickness T3 of the pressure-sensitive adhesive layer is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, still more preferably 10 μm or more, particularly preferably 15 μm or more, and most preferably 20 μm or more. The thickness T3 of the adhesive layer is usually 35 μm or less, preferably 30 μm or less.

< Image display device >)

The image display device includes the optical laminate of the present invention or the optical laminate with an adhesive layer and an image display element (an organic EL display element or the like). The optical layered body is disposed on the observation side of the image display element. For example, the optical laminate may be bonded to the image display element using the adhesive layer 50.

The image display device is not particularly limited, and examples thereof include an organic electroluminescence (organic EL) display device, an inorganic electroluminescence (inorganic EL) display device, a liquid crystal display device, an electroluminescence display device, and the like.

The image display device can be used as mobile devices such as smart phones and tablet computers, televisions, digital photo frames, electronic billboards, measuring instruments or metering instruments, office equipment, medical equipment, electric computing equipment and the like.

Examples

Hereinafter, the present invention will be described more specifically by way of examples and comparative examples, but the present invention is not limited to these examples. Hereinafter, the parts and% of the amount, content used are mass-based unless otherwise specified.

< Measurement and evaluation >

(1) Thickness of layer or film

Unless otherwise specified, the thickness of the layer or film was measured using a laser microscope (LEXT, manufactured by Olympic Co., ltd.) or a digital micrometer (MH-15M, manufactured by Nikon Co., ltd.).

(2) Tensile elastic modulus E (85 ℃ C.)

For the protective films 1 to 3 described later, measurement samples were prepared as follows, and the tensile elastic modulus E was measured. A laminate including a protective film and a support base material, which will be described later, is bonded to the adhesive backing paper 17 on the protective film side. The laminate thus obtained was cut into a size of 60mm by 200mm with the bonded product of the adhesive backing paper 17. The tape backing paper 17 has a cut-out portion 18 cut out in a rectangular shape of 10mm×140mm at the center. After cutting, the support substrate is peeled off. Thus, a sample shown in FIG. 3 was obtained. The protective film 16 (any one of the protective films 1 to 3) is present at the portion of the cut-out portion 18, and the tape backing paper 17 is bonded to the protective film 16 at the other portion. Then, a rectangular portion (a portion surrounded by a broken line in fig. 3) of 10mm×60mm was cut so as to include the cut-out portion 18 of the adhesive backing paper 17, and this was used as a measurement sample of the tensile elastic modulus E [ MPa ]. The tensile elastic modulus E was measured in accordance with JIS K7161. The tensile test was performed as follows: the backing paper portions (hatched portions in FIG. 3) at both ends of the measurement sample were held and stretched at a speed of 1 mm/min. The tensile test was performed at a temperature of 85℃and a relative humidity of 50% RH.

The tensile modulus E was measured in the same manner as described above (without the step of peeling off the support base material after cutting), except that the protective film 4 was bonded to the tape backing paper 17 instead of the laminate including the protective film and the support base material, to obtain a bonded product.

(3) Phase difference value of layer or film

The phase difference value [ nm ] at 550nm of the layer or film was measured by using a phase difference measuring device (KOBRA-WR, manufactured by prince measuring instruments Co., ltd.).

(4) Boron content of polarizer

0.2G of the polarizing plate was dissolved in 200g of a 1.9 mass% mannitol aqueous solution. The resulting aqueous solution was titrated with 1mol/L NaOH aqueous solution, and the amount of NaOH solution required for neutralization was compared with a standard curve to calculate the boron content [ mass% ] of the polarizer.

(5) Storage modulus G' of adhesive layer (23 ℃ C.)

The storage modulus G' of the adhesive layer was measured using a viscoelasticity measuring device (MCR-301, anton Paar Co.). The adhesive layers similar to those used in examples and comparative examples were each 30mm wide by 30mm long, and after a plurality of release films were peeled off and bonded to a measuring table so that the thickness became 200 μm, the release films were bonded to a measuring chip (PP 25, anton Paar corporation) and measured under conditions of a temperature range of-20 to 100 ℃, a frequency of 1.0Hz, a deformation amount of 1%, a normal force of 1N, and a heating rate of 5 ℃/min, to obtain a storage modulus G' [ MPa ] at a temperature of 23 ℃.

(6) Evaluation of warpage

From the optical laminate with an adhesive layer, an evaluation sample was produced by cutting a sample into 105mm×55mm with an axis rotated 45 degrees clockwise with respect to the MD direction of the polarizing plate as 0 degree as a long side, and then bonding the sample to an alkali-free glass (product number: EAGLE XG (registered trademark) manufactured by Corning corporation) having a thickness of 116mm×67mm×0.2 cm. The sample for evaluation was placed in an oven, heated at 105℃for 30 minutes, taken out for 1.5 hours, and then the warpage amount of the sample for evaluation was calculated by using the CNC image measuring system "NEXIV VMZ R-4540" manufactured by Nikon, and the warpage was evaluated according to the following criteria in an environment where the temperature was 23℃and the relative humidity was 55% RH. The warpage amount was defined as the largest height change amount among the height change amounts of the 4 vertices of the sample for evaluation before and after being put into the oven. The heights of 4 vertices of the evaluation sample were measured as the distances from the table surface to the vertices when the evaluation sample was placed on a horizontal table with the concave side of the evaluation sample facing upward.

A': the warpage is less than 0.60mm

A: the warpage amount is more than 0.60mm and less than 0.70mm

B': the warpage amount is more than 0.70mm and less than 0.80mm

B: the warpage amount is more than 0.80mm and less than 0.90mm

C': the warpage amount is more than 0.90mm and less than 0.95mm

C: the warpage amount is more than 0.95mm and less than 1.00mm

D: the warpage is 1.00mm or more and less than 1.40mm

E: the warp amount is more than 1.40mm

(7) Evaluation of Metal Corrosion on the basis of optical laminates

A glass substrate (manufactured by Geomatec Co.) having a metal layer formed by sputtering on the surface of an alkali-free glass with a metal aluminum layer having a thickness of about 500nm was prepared. Next, the optical layered bodies with the adhesive layers obtained in examples and comparative examples were cut into a size of 50mm×60mm, and a metal aluminum layer side of a glass substrate with a metal layer was bonded to the adhesive layer, thereby producing a sample for evaluation, in which an alkali glass was bonded to a polarizing plate using an adhesive. After the sample for evaluation was stored in an oven at a temperature of 85 ℃ and a relative humidity of 85% rh for 240 hours, light was irradiated from the back surface of the glass substrate with a metal layer, the state of the metal layer (the portion of the optical laminate to which the cut piece was bonded) of the sample for evaluation was observed from the surface of the alkali-free glass on the polarizer side by a magnifying glass, and the metal corrosion was evaluated according to the following criteria based on the degree of light leakage observed in the metal layer.

A: hardly see light leakage

B: light leakage was observed at a portion of angle 4

(8) Evaluation of damp-heat durability

An optical laminate for wet heat durability evaluation was produced in the same manner as in examples 1 to 27 and comparative example 1, except that the laminate X including the protective film 4, the adhesive layer 3, the polarizing plate, the adhesive layer, and the protective film was laminated on the laminate X via the adhesive layer 3 in the production of the optical laminates described in examples 1 to 27 and comparative example 1, which will be described later. The optical laminate for wet heat durability evaluation comprises, in order, a protective film 4/an adhesive layer 3/a polarizing plate/an adhesive layer/a protective film/an adhesive layer/a retardation film a/an adhesive layer/a retardation film B.

From the optical laminate for evaluation of wet heat durability, a sheet body having a size of 3cm×3cm was cut. In the monolithic body, 1 set of 2 sides opposing each other are parallel to the absorption axis direction of the polarizing plate. The retardation film B side of the monolithic body was bonded to a glass substrate via an adhesive layer to obtain a measurement sample. The glass substrate used was an alkali-free glass product name "Eagle XG" manufactured by Corning corporation.

The obtained measurement sample was measured for MD transmittance and TD transmittance in the wavelength range of 380 to 780nm using a spectrophotometer with an integrating sphere (product name "V7100" manufactured by Japanese Specification Co., ltd.), and the monomer transmittance at each wavelength was calculated. The calculated monomer transmittance was calculated by JIS Z8701: 1999 "2-degree field of view (C light source) of XYZ color system and X10Y10Z10 color system", and obtaining the visibility correction polarization degree (Py) before the wet heat durability test. The measurement sample was set on a spectrophotometer with an integrating sphere so that light was incident from the protective film 4 side with the glass substrate side as the detector side.

Next, the measurement sample was left to stand in a hot and humid environment at a temperature of 65 ℃ and a relative humidity of 90% for 240 hours, and further left to stand in an environment at a temperature of 23 ℃ and a relative humidity of 60% for 24 hours, and was subjected to a hot and humid endurance test. After the wet heat durability test, the visibility correction polarization degree Py was obtained by the same method as before the wet heat durability test. The polarization degree Py was corrected based on the visibility after and before the wet heat durability test, the change amount of Py was calculated based on the following formula, and the wet heat durability was evaluated based on the following criteria.

Change amount (%) = |py (after wet heat durability test) -Py (before wet heat durability test) |

(9) Evaluation of thermal shock resistance

As an optical laminate for thermal shock resistance evaluation, an optical laminate having the same constitution as that of the optical laminate for wet heat durability evaluation was produced. The optical laminate for evaluating thermal shock resistance comprises, in order, a protective film 4/an adhesive layer 3/a polarizing plate/an adhesive layer/a protective film/an adhesive layer/a retardation film a/an adhesive layer/a retardation film B.

From the optical laminate for thermal shock resistance evaluation, a sheet body of 100mm×100mm in size was cut. In the monolithic body, 1 set of opposing 2 sides are at an angle of 45 ° with respect to the absorption axis direction of the polarizer. The retardation film B side of the monolithic body was bonded to a glass substrate via an adhesive layer to prepare a measurement sample. The glass substrate used was an alkali-free glass product name "Eagle XG" manufactured by Corning corporation.

Next, a pen tip of an ericsson pen (model 318, ericsson corporation) set to a load of 10N was pressed against the surface of the protective film 4 of the measurement sample to form a starting point. The same starting points are set at equal intervals at the other 2 (3 in total). The starting points at 3 are formed at equal intervals on a diagonal line orthogonal to the absorption axis direction of the polarizing plate. Then, the thermal shock property test was performed as 1 cycle by leaving it at-30℃for 30 minutes and at 60℃for 30 minutes, and the test was performed for 10 cycles. As a thermal shock test, TSA-303EL-W manufactured by ESPEC Co., ltd was used. After 10 cycles, the length of the crack generated from each starting point was measured. The average value of the lengths of the cracks generated from the starting point at 3 was taken as the crack length (mm). Based on the obtained crack length, the thermal shock resistance was evaluated according to the following criteria.

A: crack length is less than 20mm

B: the crack length is more than 20mm

[ Production of polarizer ]

(1) Production of polarizer 1

A polyvinyl alcohol film having a thickness of 20 μm, a polymerization degree of 2400, and a saponification degree of 99.9% or more was uniaxially stretched to a stretching ratio of 4.5 times in a dry manner, and immersed in a dyeing bath at 28℃containing 0.05 part of iodine and 5 parts of potassium iodide per 100 parts of water, while maintaining the stretched state.

Next, the resultant solution was immersed in an aqueous solution of boric acid at 64 ℃ containing 1.1 parts of boric acid and 15 parts of potassium iodide with respect to 100 parts of water for 110 seconds. Next, the solution was immersed in an aqueous boric acid solution at 67 ℃ containing 5.5 parts of boric acid and 15 parts of potassium iodide with respect to 100 parts of water for 30 seconds. Then, the polarizing plate 1 was obtained by washing with water and drying with pure water at 10 ℃. The boron content of the polarizing plate 1 measured by the above method was 1.7 mass%. The thickness T1 of the polarizing plate 1 was 8. Mu.m. In addition, the visibility correction monomer transmittance Ty of the polarizing plate 1 was 42.7%.

(2) Production of polarizer 2

A polyvinyl alcohol film having a thickness of 20 μm, a polymerization degree of 2400, and a saponification degree of 99% or more was uniaxially stretched on a hot roll to a stretching ratio of 4.1 times, and immersed in a dyeing bath containing 0.05 part of iodine and 5 parts of potassium iodide per 100 parts of water at 28℃while maintaining the stretched state.

Next, the mixture was immersed in an aqueous boric acid solution containing 5.5 parts of boric acid and 15 parts of potassium iodide with respect to 100 parts of water at 64℃for 110 seconds. Next, the solution was immersed in an aqueous boric acid solution containing 2.3 parts of boric acid and 15 parts of potassium iodide with respect to 100 parts of water at 67 ℃ for 30 seconds. Then, the polarizing plate 2 was obtained by washing with water and drying with pure water at 10 ℃. The thickness T1 of the polarizing plate 2 was 8. Mu.m, and the boron content was 3.2 mass%. The visibility correction monomer transmittance Ty of the polarizing plate 2 was 42.7%.

(3) Production of polarizer 3

A polyvinyl alcohol film having a thickness of 20 μm, a polymerization degree of 2400, and a saponification degree of 99% or more was uniaxially stretched on a hot roll to a stretching ratio of 4.1 times, and immersed in a dyeing bath containing 0.05 parts of iodine and 5 parts of potassium iodide per 100 parts of water at 28℃while maintaining the stretched state.

Next, the mixture was immersed in an aqueous boric acid solution containing 5.5 parts of boric acid and 15 parts of potassium iodide with respect to 100 parts of water at 64℃for 110 seconds. Next, the solution was immersed in an aqueous boric acid solution containing 5.5 parts of boric acid and 15 parts of potassium iodide with respect to 100 parts of water at 67 ℃ for 30 seconds. Then, the polarizing plate 3 was obtained by washing with water and drying with pure water at 10 ℃. The thickness T1 of the polarizing plate 3 was 8 μm, and the boron content was 4.3 mass%. The visibility correction monomer transmittance Ty of the polarizing plate 3 was 42.7%.

[ Preparation and preparation of protective film ]

(1) Production of protective film 1

A polyethylene terephthalate film (PET film) having a thickness of 38 μm (TN 100, manufactured by Toyo Kagaku Co., ltd.) was prepared as a support substrate, and a release layer containing a non-silicone release agent was provided. In addition, the following components were blended to prepare a composition containing a thermoplastic resin.

Cyclic polyolefin resin (ARTON G7810, manufactured by JSR Co., ltd., mw:14 tens of thousands), cyclic polyolefin resin having a carboxylic acid group: 10 parts of

Toluene: 90 parts of

After the composition containing the thermoplastic resin was applied onto a release layer supporting a substrate by a back coating method using a die, the applied layer was dried at 40 ℃ for 1 minute, at 70 ℃ for 1 minute, at 100 ℃ for 1 minute, and then at 130 ℃ for 2 minutes, thereby producing a laminate having a cyclic polyolefin resin layer with a thickness T2 of 2 μm as the protective film 1. The tensile elastic modulus E of the protective film 1 at a temperature of 85℃was 450MPa, and the in-plane phase difference at a wavelength of 550nm was 0.5nm.

(2) Production of protective film 2

A laminate having a cyclic polyolefin resin layer with a thickness T2 of 4 μm as the protective film 2 was produced in the same manner as in the production of the protective film 1 except that the coating amount of the composition containing the thermoplastic resin on the release layer of the support substrate was changed. The tensile elastic modulus E of the protective film 2 at a temperature of 85℃was 450MPa, and the in-plane phase difference at a wavelength of 550nm was 0.5nm.

(3) Production of protective film 3

As a support base material, a film having a release layer containing a silicone-based release agent on a polyester film (Lumirror R75X manufactured by ori corporation) having a thickness of 50 μm was prepared. Further, a composition containing an ultraviolet curable resin (solid content: 30%) was prepared by mixing the following components and diluting with methyl ethyl ketone.

Butyl acetate/ethyl acetate solution of (meth) acrylic resin (DIC Co., ltd. "UNIDIC V-6850%, solid content concentration 50%): 190 parts

Urethane acrylate oligomer (made by japan chemical industry co. "violet UV 3200B"): 5 parts of

Alpha hydroxyacetophenone photopolymerization initiator (Irgacure 184, manufactured by BASF Japan corporation): 3 parts of

The composition containing the ultraviolet curable resin was applied onto a release layer of a support substrate using a slot coater, and then the applied layer was dried at 80℃for 30 seconds. Next, a laminate having a cured resin layer having a thickness T2 of 2 μm and containing a cured product of a (meth) acrylic resin as the protective film 3 was produced by curing the laminate by irradiation with ultraviolet rays under conditions of an oxygen partial pressure of 0.1% by volume or less, an illuminance of ultraviolet rays of 400W/cm ², and an accumulated light amount of ultraviolet rays of 120mJ/cm ² using a high-pressure mercury lamp. The tensile elastic modulus E of the protective film 3 at a temperature of 85℃was 940MPa, and the in-plane phase difference at a wavelength of 550nm was 0.5nm.

(4) Preparation of protective film 4

As the protective film 4, a cyclic polyolefin resin film (trade name "ZEONOR" manufactured by ZEON corporation, japan) having a thickness T2 of 13 μm was prepared. The tensile elastic modulus E of the protective film 4 at a temperature of 85 ℃ was 620MPa.

[ Preparation of active energy ray-curable adhesive ]

(1) Preparation of active energy ray-curable adhesive 1

After the following components were mixed, deaeration was performed to prepare an active energy ray-curable adhesive 1.

(Cationically polymerizable Compound)

Neopentyl glycol diglycidyl ether (trade name: EX-211L,Nagase ChemteX, manufactured by k.co.): 30 parts of

3-Ethyl-3 { [ (3-ethyloxetan-3-yl) methoxy ] methyl } oxetan (trade name: OXT-221, manufactured by Toyama Synthesis Co., ltd.): 13 parts of

Bisphenol A type epoxy resin (trade name: EP-4100E, product name: ADEKA, viscosity 13 Pa.s (temperature 25 ℃ C.): 45 parts of

Aromatic-containing oxetane compound (trade name: TCM-104, manufactured by TRONLY): 12 parts of

(Photo cationic polymerization initiator)

Trade name: CPI-100P (50% propylene carbonate solution, manufactured by San-Apro Co., ltd.: 4.5 parts (substantial solid content 2.25 parts)

(Photosensitizing aid)

1, 4-Diethoxynaphthalene: 1 part of

(2) Preparation of active energy ray-curable adhesive 2

The following components were mixed and then defoamed to prepare an active energy ray-curable adhesive 2.

(Cationically polymerizable Compound)

3, 4-Epoxycyclohexane carboxylic acid 3',4' -epoxycyclohexylmethyl ester (trade name: CEL2021P, manufactured by Daicel Co., ltd.): 70 parts of

Neopentyl glycol diglycidyl ether (trade name: EX-211,Nagase ChemteX, manufactured by k.co.): 20 parts of

2-Ethylhexyl glycidyl ether (trade name: EX-121,Nagase ChemteX Co., ltd.): 10 parts of

(Photo cationic polymerization initiator)

Trade name: CPI-100 (manufactured by San-Apro Co., ltd., 50% propylene carbonate solution): 4.5 parts (substantial solid content 2.25 parts)

(Photosensitizing aid)

1, 4-Diethoxynaphthalene: 2 parts of

[ Production of adhesive layer ]

The following acrylic pressure-sensitive adhesive layers 1 to 3, each having both sides bonded to a release film, were produced.

(1) Production of adhesive layer 1

(1-1) Preparation of acrylic resin solution 1

A mixed solution of 81.8 parts of ethyl acetate, 90.0 parts of butyl acrylate, 5.0 parts of methyl acrylate and 5.0 parts of acrylic acid was charged into a reaction vessel equipped with a condenser, a nitrogen inlet, a thermometer and a stirrer, and the internal temperature was raised to 55℃while the air in the apparatus was replaced with nitrogen gas to remove oxygen. Then, a solution of 0.15 part of azobisisobutyronitrile (polymerization initiator) dissolved in 10 parts of ethyl acetate was added in the entire amount. After the polymerization initiator was added, the reaction vessel was continuously charged with ethyl acetate at an addition rate of 17.3 parts/hr while maintaining the internal temperature at 54 to 56℃for 1 hour, and the addition of ethyl acetate was stopped at a point in time when the concentration of the acrylic resin became 35 mass%, and the reaction vessel was further kept at that temperature until 6 hours passed from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the acrylic resin to 20 mass%, thereby preparing an acrylic resin solution 1. The weight average molecular weight Mw of the obtained acrylic resin was 160 ten thousand, and the molecular weight distribution Mw/Mn was 4.5. The Mw and Mn were measured as follows: 2 columns of "TSKGEL GMHHR-H (S)" manufactured by Tosoh Co., ltd. Were arranged in series in a GPC apparatus, and tetrahydrofuran was used as an eluent, and the measurement was performed by standard polystyrene conversion under conditions of a sample concentration of 2mg/mL, a sample introduction amount of 100. Mu.L, a temperature of 40℃and a flow rate of 1 mL/min.

(1-2) Preparation of adhesive composition 1

To 100 parts of the solid content of the acrylic resin solution 1 obtained in (1-1), 0.15 part of a crosslinking agent (trade name "Coronate L" (ethyl acetate solution (solid content concentration: 75%) of trimethylolpropane adduct of toluene diisocyanate) made by Tosoh Co., ltd.) and 0.2 part of a silane coupling agent (trade name "KBM-403" made by Xinyue chemical Co., ltd.) were added based on the active ingredient, and ethyl acetate was further added so that the solid content concentration became 13%, to obtain an adhesive composition 1.

(1-3) Preparation of adhesive layer 1

The pressure-sensitive adhesive composition 1 prepared in (1-2) was applied to a release film made of a polyethylene terephthalate film (release treated surface "PLR-382190" available from Wandeke Co., ltd.) subjected to release treatment so that the thickness T3 after drying became 25 μm using an applicator, and dried at 100℃for 1 minute to prepare a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet). Next, the surface of the obtained pressure-sensitive adhesive layer opposite to the release film side was bonded to a release-treated surface of a release film made of polyethylene terephthalate film (PET-251130 obtained from lindaceae, inc.) subjected to a release treatment to prepare a pressure-sensitive adhesive layer 1. The storage modulus G' of the adhesive layer 1 at a temperature of 23℃was 0.0255MPa.

(2) Production of adhesive layer 2

Adhesive layer 2 was produced in the same manner as in the production of adhesive layer 1 except that adhesive composition 1 prepared in (1-2) above was applied so that the thickness T3 after drying became 15 μm, and dried to produce an adhesive layer. The storage modulus G' of the adhesive layer 2 at a temperature of 23℃was 0.0255MPa.

(3) Production of adhesive layer 3

(3-1) Preparation of acrylic resin solution 3

A mixed solution of 100 parts of ethyl acetate, 99.0 parts of butyl acrylate, 0.5 parts of 2-hydroxyethyl acrylate and 0.5 parts of acrylic acid was charged into a reaction vessel equipped with a condenser, a nitrogen inlet, a thermometer and a stirrer, and the internal temperature was raised to 55℃while the air in the apparatus was replaced with nitrogen gas to remove oxygen. Then, a solution of 0.12 part of azobisisobutyronitrile (polymerization initiator) dissolved in 10 parts of ethyl acetate was added in the entire amount. After the polymerization initiator was added, the reaction vessel was continuously charged with ethyl acetate at an addition rate of 17.3 parts/hr while maintaining the internal temperature at 54 to 56℃for 1 hour, and the addition of ethyl acetate was stopped at a point in time when the concentration of the acrylic resin became 35 mass%, and the reaction vessel was further kept at that temperature until 6 hours passed from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the acrylic resin to 20 mass%, thereby preparing an acrylic resin solution 3. The weight average molecular weight Mw of the obtained acrylic resin was 170 million, and the molecular weight distribution Mw/Mn was 3.9. The Mw and Mn were measured as follows: 2 columns of "TSKGEL GMHHR-H (S)" manufactured by Tosoh Co., ltd. Were arranged in series in a GPC apparatus, and tetrahydrofuran was used as an eluent, and the measurement was performed by standard polystyrene conversion under conditions of a sample concentration of 2mg/mL, a sample introduction amount of 100. Mu.L, a temperature of 40℃and a flow rate of 1 mL/min.

(3-2) Preparation of adhesive composition 3

To 80 parts of the solid content of the acrylic resin solution 3 obtained in the above (3-1), 20 parts (solid content) of a difunctional acrylate (obtained from Xinzhou chemical industry Co., ltd.; product No. A-DOG "), 2.5 parts (product name" Coronate L "manufactured by Tosoh Co., ltd.; ethyl acetate solution of trimethylolpropane adduct of toluene diisocyanate (solid content concentration 75%) on an active ingredient basis, 1.5 parts (product name" Irgacure500 "manufactured by Ciba SPECIALTY CHEMICALS Co., ltd.; product name" KBM-403 ") of a photopolymerization initiator (product name" KBM-403 "manufactured by Xinyue chemical industry Co., ltd.) and 0.3 parts (product name" KBM-403 ") of a silane coupling agent (product name" Xinyue chemical industry Co., ltd.) were added, and ethyl acetate was further added so that the solid content concentration becomes 13%, thereby obtaining an adhesive composition 3.

A-DOG is a diacrylate of an acetal compound of hydroxypivaldehyde and trimethylolpropane, and has a structure represented by the following formula.

[ Chemical formula 6]

(3-3) Preparation of adhesive layer 3

The pressure-sensitive adhesive composition 3 prepared in (3-2) was applied to a release film made of a polyethylene terephthalate film (release treated surface "PLZ-383030" available from Wandeke Co., ltd.) subjected to release treatment so that the thickness T3 after drying became 5. Mu.m, using an applicator, and dried at 100℃for 1 minute to prepare a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet). Then, the surface of the obtained pressure-sensitive adhesive layer on the side opposite to the release film side was bonded to a release-treated surface of a release film made of a polyethylene terephthalate film subjected to a release treatment (PLR-381031, available from Wandeke Co., ltd.). Next, ultraviolet rays were irradiated under the following conditions to produce an adhesive layer 3. The storage modulus G' of the adhesive layer 3 at a temperature of 23℃was 0.125MPa.

< UV irradiation Condition >)

H bulb Using Fusion UV lamp System (Fusion UV Systems Co.)

Cumulative light amount of UVA in UV wavelength region 250mJ/cm ² (based on measurement value by measuring instrument: UV Power PuckII manufactured by fusion UV Co., ltd.)

[ Production of phase element ]

(1) Fabrication of phase element 1

(1-1) Preparation of phase-difference film A

(1-1-1) Preparation of composition A for Forming photo-alignment film

The light-oriented material (weight average molecular weight: 50000, m: n=50:50) having the following structure was produced according to the method described in japanese patent application laid-open No. 2021-196514. The photo-alignment film-forming composition a was prepared by mixing 2 parts of photo-alignment material with 98 parts of cyclopentanone (solvent) as a component, and stirring the resultant mixture at 80 ℃ for 1 hour.

Light-oriented material:

[ chemical formula 7]

(1-1-2) Production of polymerizable liquid Crystal Compound

The polymerizable liquid crystal compound (A1) and the polymerizable liquid crystal compound (A2) each having the structures shown below were prepared. The polymerizable liquid crystal compound (A1) was prepared in the same manner as described in JP-A2019-003177. The polymerizable liquid crystal compound (A2) was prepared in the same manner as described in japanese patent application laid-open No. 2009-173893.

Polymerizable liquid crystal compound (A1):

[ chemical formula 8]

Polymerizable liquid crystal compound (A2):

[ chemical formula 9]

1Mg of the polymerizable liquid crystal compound (A1) was dissolved in 10mL of chloroform to obtain a solution. The obtained solution was added to a measurement cuvette having an optical path length of 1cm, and an absorption spectrum was measured by setting the measurement sample in an ultraviolet-visible spectrophotometer (manufactured by Shimadzu corporation, "UV-2450"). The wavelength at which the maximum absorbance was reached was read from the obtained absorption spectrum, and as a result, the maximum absorption wavelength λmax was 356nm in the range of 300 to 400 nm.

(1-1-3) Preparation of composition A for Forming a retardation film

The polymerizable liquid crystal compound (A1) and the polymerizable liquid crystal compound (A2) were mixed in a mass ratio of 90:10, and obtaining a mixture. To 100 parts of the resultant mixture, 0.1 part of a leveling agent "BYK-361N" (manufactured by BM Chemie Co., ltd.) and 3 parts of "Irgacure OXE-03" (manufactured by BASF Japan Co., ltd.) as a photopolymerization initiator were added. Further, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration became 13%. This mixture was stirred at a temperature of 80℃for 1 hour, thereby preparing a composition A for forming a retardation film.

(1-1-4) Production of phase-difference film A

The composition A for forming a photo-alignment film was applied to a biaxially-oriented polyethylene terephthalate (PET) film (DIAFOIL Mitsubishi resin Co., ltd.) as a base material A by a bar coater. The obtained coating film was dried at 120℃for 2 minutes, and then cooled to room temperature, thereby forming a dried film. Then, a UV irradiation apparatus (SPOTCURE SP-9; manufactured by USHIO Motor Co., ltd.) was used to irradiate polarized ultraviolet light of 100mJ (313 nm standard), thereby obtaining a photo-alignment film A. The film thickness of the photo-alignment film A was 100nm as measured by ellipsometer M-220 manufactured by Nippon spectroscopic Co.

The composition a for forming a retardation film was applied to the obtained photo-alignment film a by a bar coater to form a coating film. The coated film was heated at 120℃for 2 minutes and dried, and then cooled to room temperature, to obtain a dried film. Next, a high-pressure mercury lamp (usaio motor company, "Unicure VB-15201 BY-a") was used to irradiate the dried film with ultraviolet light having an exposure of 500mJ/cm ² (365 nm basis) under a nitrogen atmosphere, thereby forming a retardation film a in which the polymerizable liquid crystal compound was cured in a state of being oriented in a horizontal direction with respect to the substrate surface, and a laminate a including the substrate a/photo-alignment film a/retardation film a was obtained. The film thickness of the retardation film a was 2.0 μm as measured by using a laser microscope LEXT OLS4100 manufactured by olympus corporation.

The surface of the retardation film a of the laminate a was subjected to corona treatment, and bonded to glass via an adhesive layer (manufactured by lindaceae) having a thickness of 25 μm, and the substrate a was peeled off and removed. The in-plane phase difference values for light of wavelengths 450nm, 550nm and 650nm were obtained by the Cauchy dispersion formula obtained from the measurement results of the in-plane phase difference values for light of wavelengths 448.2nm, 498.6nm, 548.4nm, 587.3nm, 628.7nm and 748.6 nm.

As a result, the in-plane phase difference values Re (450) =122 nm, re (550) =140 nm, and Re (650) =144 nm are related as follows.

Re(450)/Re(550)＝0.87

Re(650)/Re(550)＝1.03

(Wherein Re (450) represents the in-plane phase difference value with respect to light having a wavelength of 450nm, re (550) represents the in-plane phase difference value with respect to light having a wavelength of 550nm, re (650) represents the in-plane phase difference value with respect to light having a wavelength of 650 nm.)

(1-2) Preparation of phase-difference film B

(1-2-1) Preparation of composition B for Forming an alignment film

To SUNEVER SE-610 (commercially available from Nissan chemical Co., ltd.) as an alignment polymer, 2-butoxyethanol was added so that the solid content became 1%, to obtain composition B for forming an alignment film.

(1-2-2) Preparation of composition B for Forming a phase-difference film

100 Parts of a polymerizable liquid crystal compound Paliocolor LC242 (manufactured by BASF Japan Co., ltd.), 0.1 part of a leveling agent "BYK-361N" (manufactured by BYK-Chemie Co., ltd.) and 2.5 parts of a photopolymerization initiator "Omnirad907" (manufactured by IGM Resin B.V. Co.) were mixed. Further, 400 parts of propylene glycol 1-monomethyl ether 2-acetate (PGME) was added, and the resultant mixture was stirred at a temperature of 80 ℃ for 1 hour, thereby preparing a composition B for forming a retardation film.

Polymerizable liquid crystal compound LC242:

[ chemical formula 10]

(1-2-3) Preparation of phase-difference film B

As the substrate B, a cycloolefin resin (COP) film (ZF 14, manufactured by ZEON Co., ltd.) was used, one surface thereof was subjected to corona treatment using a corona treatment device (AGF-B10; manufactured by spring motor Co., ltd.), the composition B for forming an alignment film was applied to the surface thereof using a bar coater, and the film was dried at 90℃for 1 minute. The film thickness of the obtained alignment film B was measured by a laser microscope and found to be 30nm.

The composition B for forming a retardation film was applied to the obtained alignment film B by using a bar coater, and dried at 90℃for 1 minute to obtain a dried film. The above-mentioned dry film was irradiated with ultraviolet light having an exposure of 1000mJ/cm ² (365 nm basis) under a nitrogen atmosphere using a high-pressure mercury lamp (USHIO Motor Co., ltd. "Unicure VB-15201 BY-A"), to form a retardation film B, whereby a laminate B comprising a substrate B/an alignment film B/a retardation film B was obtained. The film thickness of the retardation film B was 450nm as measured by using a laser microscope LEXT OLS4100 manufactured by Olin Bas Co.

The retardation value was measured, and as a result, re (550) =1 nm and rth (550) = -75nm. Laminate B has optical properties shown by nx≡ny < nz. Since the phase difference value at the wavelength of 550nm of COP is approximately 0, the optical characteristics are not affected.

(1-3) Fabrication of phase element 1

Corona treatment was performed on each of the retardation film a of the laminate a and the retardation film B of the laminate B. An adhesive is applied to the corona-treated surface of either one of the retardation film a and the retardation film B, and the laminate a and the laminate B are bonded. The active energy ray-curable adhesive 2 described above was used as the adhesive. The corona treatment device used was AGF-B10 manufactured by Chun electric Co., ltd. The corona treatment was performed 1 time under the conditions of an output power of 0.3kW and a treatment speed of 3 m/min using the above corona treatment apparatus. The active energy ray-curable adhesive 2 was cured by irradiation of ultraviolet rays from the laminate a side, and an adhesive layer having a thickness of 1.5 μm was formed. Ultraviolet rays are irradiated so that UVA having a wavelength of 320nm to 390nm becomes 420mJ/cm ². By the above-described operations, the phase element 1 with a base material including the base material a/the photo-alignment film a/the phase difference film a/the adhesive layer/the phase difference film B/the alignment film B/the base material B was produced.

(2) Fabrication of phase element 2

(2-1) Preparation of phase-difference film C

(2-1-1) Preparation of composition C for Forming an alignment film

Water was added to commercially available polyvinyl alcohol (polyvinyl alcohol 1000 completely saponified, manufactured by Wako pure chemical industries, ltd.) and heated at 100℃for 1 hour to obtain composition C for forming an alignment film.

(2-1-2) Preparation of composition C for Forming a phase-difference film

100 Parts of a polymerizable liquid crystal compound Paliocolor LC242 (manufactured by BASF Japan Co., ltd.), 0.1 part of a leveling agent "BYK-361N" (manufactured by BYK-Chemie Co., ltd.), and 2.5 parts of "Omnirad907" (manufactured by IGM Resin B.V. Co.) as a photopolymerization initiator were added. Further, 400 parts of propylene glycol 1-monomethyl ether 2-acetate (PGME) was added, and the mixture was stirred at a temperature of 80 ℃ for 1 hour, thereby preparing a composition C for forming a retardation film.

(2-1-3) Preparation of phase-difference film C

The composition C for forming an alignment film was applied to a triacetyl cellulose (TAC) film (KC 4UY, manufactured by Konikoku Meida Co., ltd.) cut into a rectangular shape as a base material C, and then heated and dried to form an alignment film C having a thickness of 100 nm. The surface of the obtained alignment film C was subjected to a rubbing treatment at an angle of 15 ° to the longitudinal direction of the TAC film, and the retardation film-forming composition C was applied thereon by a bar coater. The obtained coating film was dried at 100℃for 1 minute, and then cooled to room temperature, to obtain a dried film. Next, the above-mentioned dry film was irradiated with ultraviolet light having an exposure of 1000mJ/cm ² (365 nm basis) under a nitrogen atmosphere using a high-pressure mercury lamp (usaio motor corporation "Unicure VB-15201 BY-a"), thereby forming a retardation film C in which the polymerizable liquid crystal compound was cured in a state of being oriented in a horizontal direction with respect to the substrate surface, and a laminate C including the substrate C/orientation film C/retardation film C was obtained. The film thickness of the obtained retardation film C was measured by a laser microscope and found to be 1.0. Mu.m. The in-plane phase difference at wavelength 550nm is Re (550) =140 nm. The difference in phase at 550nm of TAC was approximately 0, and thus had no effect on the optical characteristics. The orientation angle was 15 ° with respect to the longitudinal direction of the TAC film.

(2-2) Preparation of phase-difference film D

(2-2-1) Production of polymerizable liquid Crystal Compound

The polymerizable liquid crystal compound (A3) and the polymerizable liquid crystal compound (A4) each having the structures shown below were prepared. The polymerizable liquid crystal compound (A3) and the polymerizable liquid crystal compound (A4) are prepared in the same manner as described in japanese unexamined patent publication No. 2010-244038.

Polymerizable liquid crystal compound (A3):

[ chemical formula 11]

Polymerizable liquid crystal compound (A4):

[ chemical formula 12]

(2-2-2) Preparation of composition D for Forming a phase-difference film

The polymerizable liquid crystal compound (A3) and the polymerizable liquid crystal compound (A4) were mixed in a mass ratio of 80:20, to obtain a mixture. To 100 parts of the resultant mixture, 0.1 part of leveling agent "Megafac F-556" (DIC Co., ltd.), 2.5 parts of "Omnirad907" (IGM Resin B.V. Co.) as a photopolymerization initiator, and 0.1 part of ionic compound (B) were added. Further, 650 parts of cyclopentanone was added, and the mixture was stirred at a temperature of 80 ℃ for 1 hour, thereby preparing a composition D for forming a retardation film.

Ionic compound (B):

[ chemical formula 13]

(2-2-3) Production of phase-difference film D

A rectangular, annular polyolefin resin (COP) film (ZF 14, manufactured by ZEON Co., ltd.) as a base material D was subjected to corona treatment using a corona treatment device (AGF-B10; manufactured by CHUN motor Co., ltd.) and then coated with an orientation film-forming composition C, and dried by heating to form an orientation film C having a thickness of 100 nm. The surface of the obtained alignment film C was subjected to a rubbing treatment at an angle of 75 ° to the longitudinal direction of the COP film, and the retardation film-forming composition D was applied thereon by a bar coater. The obtained coating film was dried at 120℃for 2 minutes, and then cooled to room temperature, to obtain a dried film. Next, a high-pressure mercury lamp (usaio motor company, "Unicure VB-15201 BY-a") was used to irradiate the dried film with ultraviolet light having an exposure of 1000mJ/cm ² (365 nm basis) at 80 ℃ under a nitrogen atmosphere, thereby forming a retardation film D cured in a state where the optical axis of the polymerizable liquid crystal compound was oriented in the horizontal direction with respect to the substrate surface, and a laminate D including the substrate D/orientation film C/retardation film D was obtained. The film thickness of the obtained retardation film D was measured by a laser microscope and found to be 1.8. Mu.m. The in-plane phase difference at wavelength 550nm is Re (550) =270 nm. Since the phase difference value at the wavelength of 550nm of COP is approximately 0, the optical characteristics are not affected. The orientation angle was 75 ° with respect to the longitudinal direction of the COP film.

(2-3) Fabrication of phase element 2

The retardation film C of the laminate C and the retardation film D of the laminate D were subjected to corona treatment, respectively. An adhesive is applied to the corona-treated surface of either one of the retardation film C and the retardation film D, and the laminate C and the laminate D are bonded. The active energy ray-curable adhesive 1 described above was used as the adhesive. The corona treatment device used was AGF-B10 manufactured by Chun electric Co., ltd. The corona treatment was performed 1 time under the conditions of an output power of 0.3kW and a treatment speed of 3 m/min using the above corona treatment apparatus. The active energy ray-curable adhesive 1 was cured by irradiation of ultraviolet rays from the laminate C side, and an adhesive layer having a thickness of 1.5 μm was formed. Ultraviolet rays are irradiated so that UVA having a wavelength of 320nm to 390nm becomes 420mJ/cm ². By the above-described operations, the phase element 2 with a base material including the base material C/the alignment film C/the phase difference film C/the adhesive layer/the phase difference film D/the alignment film C/the base material D was produced.

Examples 1 to 27 >

The polarizing plate selected from the polarizing plates 1 to 3 and the protective film selected from the protective films 1 to 3 were bonded to the phase element 1, thereby obtaining an optical laminate. Next, an adhesive layer was laminated on the surface of the phase element of the optical laminate opposite to the protective film side, to obtain an optical laminate with an adhesive layer. Specifically, the following is described.

Corona treatment is applied to the surface of the polarizing plate and the surface of the laminate having the protective film on the protective film side, respectively. A water-based adhesive is applied to any one of the corona treatments, and the polarizer is bonded to the laminate having the protective film, and dried. As the aqueous adhesive, a mixture of 100 parts of water, 3 parts of carboxyl-modified polyvinyl alcohol (KURARAY POVAL KL318, manufactured by Kuraray Co., ltd.) and 1.5 parts of a water-soluble polyamide epoxy resin (Sumirez Resin 650,650, manufactured by Santa Clara chemical Co., ltd., aqueous solution having a solid content of 30%) was used. The corona treatment device used was AGF-B10 manufactured by Chun electric Co., ltd. The corona treatment was performed 1 time under the conditions of an output power of 0.3kW and a treatment speed of 3 m/min using the above corona treatment apparatus. Next, the support base material of the laminate having the protective film was peeled off and removed, and a laminate X including a polarizing plate, an adhesive layer, and a protective film was obtained.

Next, corona treatment is performed on the surface of the protective film of the laminate X and the surface exposed by peeling off the base material a of the phase element 1. The corona treatment device used was AGF-B10 manufactured by Chun electric Co., ltd. The corona treatment was performed 1 time under the conditions of an output power of 0.3kW and a treatment speed of 3 m/min using the above corona treatment apparatus. The corona-treated surface of the laminate X and the corona-treated surface of the phase element 1 are bonded via the adhesive layer 3. Then, the base material B of the phase element 1 was peeled off and removed, and an optical laminate including the polarizing plate, the adhesive layer, the protective film, the adhesive layer, the phase difference film a, the adhesive layer, and the phase difference film B in this order was obtained. Finally, an adhesive layer was laminated on the retardation film B side of the optical laminate, to obtain an optical laminate with an adhesive layer. The types of the polarizing plate, the protective film, the phase element, and the adhesive layer (adhesive layer laminated on the surface of the phase element opposite to the protective film side) used in each example are shown in the following table.

Comparative example 1 >

An optical laminate including a polarizing plate, an adhesive layer, a protective film, an adhesive layer, a retardation film D, an adhesive layer, and a retardation film C in this order was produced in the same manner as in examples 1 to 27, except that the protective film 4 was used as the protective film and the phase element 2 was used as the phase element, and the adhesive layer was laminated thereon to produce an optical laminate with an adhesive layer. In comparative example 1, since the protective film 4 was used, the step of peeling and removing the support base material was not performed. The pressure-sensitive adhesive layer 2 is used as the pressure-sensitive adhesive layer laminated on the surface of the phase element opposite to the protective film side.

The results of evaluation of warpage and evaluation of metal corrosion of the optical laminates with adhesive layers produced in examples and comparative examples are shown in table 1 below. The evaluation of the wet heat durability and the evaluation of the thermal shock resistance are shown in table 2 below.

TABLE 1

TABLE 2

Examples 28 to 54 >

An optical laminate and an optical laminate with an adhesive layer were produced in the same manner as in examples 1 to 27, except that the phase element 2 was used instead of the phase element 1. The results of the evaluation of warpage, the evaluation of metal corrosion, the evaluation of wet heat durability and the evaluation of thermal shock resistance in examples 28 to 54 were the same as those in examples 1 to 27, respectively.

Description of the reference numerals

10: Polarizing plate, 16: protective film, 17: adhesive backing paper, 18: cut-out, 20: protective film, 30: phase element, 41: 1 st adhesive layer, 42: 2 nd adhesive layer, 50: an adhesive layer.

Claims

1. An optical laminate comprising a polarizing plate, a protective film, and a phase element in this order,

The thickness T1 of the polarizer is 15 μm or less,

When the tensile elastic modulus of the protective film at a temperature of 85 ℃ is set to E and the thickness is set to T2, the following formulas (i) and (ii) are satisfied:

E×T2≤8000 (i)

T2≤7(ii)，

Wherein, the unit of E is MPa, and the unit of T2 is μm.

2. The optical stack according to claim 1, wherein E x T2 has a value of 1850 or less.

3. The optical stack according to claim 1, wherein the phase element comprises a phase difference film.

4. The optical laminate according to claim 1, wherein the protective film comprises a cyclic polyolefin-based resin.

5. The optical laminate according to claim 1, wherein the protective film has an in-plane phase difference value of 10nm or less at a wavelength of 550 nm.

6. The optical laminate according to claim 1, comprising an adhesive layer between the polarizer and the protective film.

7. The optical laminate according to claim 1, wherein the polarizer has a boron content of 0.5 mass% or more and 5.5 mass% or less.

8. An optical laminate with an adhesive layer comprising:

the optical stack of any one of claims 1-7; and

When the storage modulus of the pressure-sensitive adhesive layer at a temperature of 23 ℃ is G' and the thickness is T3, the following formula (iii) is satisfied:

G’/T3≤5(iii)，

wherein G' has the unit of MPa and T3 has the unit of μm.

9. An image display device comprising the optical laminate according to any one of claims 1 to 7.

10. An image display device comprising the optical laminate with an adhesive layer of claim 8.