JP7567785B2 - Manufacturing method of image display device and laminate for polarizer transfer - Google Patents

Description

The present invention relates to a method for manufacturing an image display device and a laminate for polarizer transfer.

For example, in liquid crystal display devices, polarizing plates are attached to both the visible side and the light source side of the liquid crystal cell, while in organic electroluminescence display devices, a circular polarizing plate is attached to the visible side of the organic electroluminescence cell. Conventionally, these polarizing plates are made by attaching a polarizer protective film to a polarizer, and the polarizer protective film has been a rigid film of 40 to 100 μm such as triacetyl cellulose (TAC), acrylic resin, cyclic polyolefin (COP), or polyethylene terephthalate (PET). Furthermore, typically, an optical compensation film is laminated between the polarizing plate and the image display cell in the case of liquid crystal display devices, and a λ/4 phase difference film is laminated in the case of organic electroluminescence display devices.

In line with the recent trend towards thinner image display devices, a method has been proposed in which an adhesive layer is provided on the polarizer surface of a polarizing plate having a polarizer protective film on only one side of the polarizer, and the polarizer and image display cell are directly attached to each other (for example, Patent Document 1). However, the polarizer protective film itself is essential in terms of ease of handling the polarizer, prevention of scratches on the polarizer surface due to contact with other objects, prevention of deterioration of the polarizer surface due to moisture, detergents, harmful gas components in the environment, etc., and because the polarizer protective film itself has a thickness of several tens of μm, it is not adequate for use in thin image display devices.

JP 2010-277018 A

The present invention has been made in response to the problems of the conventional technology. That is, one object of the present invention is to provide a method for manufacturing an image display device that can suppress scratches and deterioration of the polarizer while responding to further thinning.

The present inventors have conducted extensive research to achieve the above object, and as a result have completed the present invention. That is, the present invention includes the following aspects.
Item 1.
A method for manufacturing an image display device, comprising a step of laminating a polarizer transfer laminate LP1 onto at least one side of an image display cell so that the polarizer of the polarizer transfer laminate LP1, which has a coating layer and a polarizer laminated in this order on a release film, is positioned on the image display cell side.
Item 2.
A method for manufacturing an image display device, comprising: (A) a step of laminating a polarizer transfer laminate LP1 onto one side of an image display cell so that a polarizer of the polarizer transfer laminate LP1, which has a coating layer and a polarizer laminated in this order on a release film, is positioned on the image display cell side; and (B) a step of laminating a polarizer transfer laminate LP2 onto the other side of the image display cell so that a polarizer of the polarizer transfer laminate LP2, which has a polarizer laminated on a release film, is positioned on the image display cell side.
Item 3.
Item 3. The method for producing an image display device according to item 1 or 2, wherein the polarizer transfer laminate LP1 has a retardation layer on the opposite side of the polarizer to the coating layer.
Item 4.
Item 4. The method for producing an image display device according to Item 2 or 3, wherein the polarizer transfer laminate LP2 has a retardation layer on the side of the polarizer opposite to the release film.
Item 5.
Item 5. The method for producing an image display device according to any one of Items 2 to 4, wherein the polarizer transfer laminate LP2 has a coating layer between the release film and the polarizer.
Item 6.
Item 6. The method for producing an image display device according to any one of items 1 to 5, wherein the coating layer includes any one of a hard coating layer, a reflection reducing layer, and an antistatic layer.
Item 7.
7. The method for producing an image display device according to any one of Items 1 to 6, wherein the image display cell is a liquid crystal display cell.
Item 8.
7. The method for producing an image display device according to claim 1, 3 or 6, wherein the image display cell is an organic EL display cell.
Item 9.
A laminate for polarizer transfer, in which a coating layer and a polarizer are laminated in this order on a release film.
Item 10.
Item 10. The laminate for polarizer transfer according to item 9, further comprising a retardation layer on the opposite side of the coating layer of the polarizer.

The present invention makes it possible to manufacture image display devices that can be made even thinner and that can suppress scratches and deterioration of polarizers.

In one embodiment of the present invention, the manufacturing method for an image display device preferably includes a step of laminating a polarizer transfer laminate LP1 on at least one side of the image display cell so that the polarizer of the polarizer transfer laminate LP1, which has a coating layer and a polarizer laminated in this order on a release film, is positioned on the image display cell side.

In one embodiment of the present invention, a method for producing an image display device includes the steps of:
It is preferable that the method includes the steps of (A) laminating a polarizer transfer laminate LP1 onto one side of the image display cell so that the polarizer of the polarizer transfer laminate LP1, which has a coating layer and a polarizer laminated in this order on a release film, is positioned on the image display cell side, and (B) laminating a polarizer transfer laminate LP2 onto the other side of the image display cell so that the polarizer of the polarizer transfer laminate LP2, which has a polarizer laminated on a release film, is positioned on the image display cell side.

(Polarizer transfer laminate LP1)
LP1 preferably has a release film, a coating layer, and a polarizer in this order.

(Release film)
As the release film of LP1, a film widely used as a release film can be appropriately used. The release film is composed of a single layer or multiple layers, and includes at least a base film. The base film is preferably a resin film. The resin of the resin film is not particularly limited, and any resin film such as polyester, polycarbonate, polyamide, polyimide, polyamideimide, polystyrene, triacetyl cellulose, polypropylene, and cyclic polyolefin can be used without limitation. Among these, polyester is preferable from the viewpoint of mechanical strength, heat resistance, supply stability, etc., and polyethylene terephthalate is more preferable. In addition, the base film may be an unstretched film or a stretched film. When it is a stretched film, it may be a uniaxially stretched film or a biaxially stretched film. Among them, a biaxially stretched polyethylene terephthalate film is preferable.

If the base film itself has releasability, the base film can be used as a release film as is. In addition, the base film may be subjected to surface treatment such as corona treatment, plasma treatment, or flame treatment to adjust the releasability of the base film.

The release film may have a release layer on the base film. Examples of the release layer include silicone-based, amino resin-based, alkyd resin-based, and long-chain acrylic resin-based layers, and the composition and type can be appropriately selected according to the required release force.

The release film may have an easy-adhesion layer between the base film and the release layer. As the easy-adhesion layer, those conventionally used in each base film such as polyester-based, acrylic-based, and polyurethane-based layers can be used, and can be selected according to the base film and/or release layer to be used.

(Coat layer)
The coating layer of LP1 may be of any type, as long as it is composed of a single layer or multiple layers, and the constituent layers (in the case of multiple layers, each layer) are formed by coating. The coating layer is preferably provided on the release surface of the release film. The upper limit of the thickness of the coating layer is preferably 50 μm, more preferably 30 μm, and even more preferably 20 μm. The lower limit of the thickness of the coating layer is not particularly limited, but is preferably 0.1 μm, more preferably 0.5 μm, and even more preferably 1 μm. When the coating layer is composed of multiple layers, it is preferable that the total thickness of the multiple layers satisfies the above. By reducing the thickness of the coating layer, the image display device can be made even thinner.

The coating layer may be made of a resin. Examples of the resin include, but are not limited to, polyester resin, acrylic resin, polyurethane resin, polyvinyl alcohol, epoxy resin, polyvinyl alcohol, polyvinyl acetate, etc. Only one type of resin may be used, or two or more types may be used in combination.

The resin may be crosslinked. Examples of crosslinking agents include isocyanate compounds, epoxy resins, melamine resins, oxazoline compounds, carbodiimide compounds, etc. Only one type of crosslinking agent may be used, or two or more types may be used in combination.

The coating layer may be made by curing (thermally curing, photocuring) acrylic monomers and/or oligomers.

Examples of the coating layer include a reflection reduction layer, a hard coat layer, and an antistatic layer. The coating layer may have a function for protecting the polarizer, separately from or in addition to the reflection reduction function, hard coat function, and antistatic function. Examples of the protective function for the polarizer include a function for protecting the polarizer from scratches and damage before assembly into an image display device, a function for protecting the polarizer from scratches and damage caused by contact with other members or the outside when the image display device is used, and a function for protecting the polarizer from harmful substances (liquids such as water, detergents, and alcohols, harmful gases such as SOx and NOx, etc.) to which the image display device is exposed in the environment in which it is used.

(Reflection Reduction Layer)
The reflection-reducing layer may be of any type as long as it can reduce the reflectance at the interface with air. The reflection-reducing layer can suppress reflection from external light, making images easier to see.

The upper limit of the reflectance of the reflection-reduction layer is preferably 5%, more preferably 4%, even more preferably 3%, particularly preferably 2%, and most preferably 1.5%. By setting the reflectance at or below the above range, the display screen becomes easier to see. The lower limit of the reflectance is not particularly specified, but is preferably 0.01%, and more preferably 0.1%. The reflectance is measured by the following method:
A polarizer transfer laminate is attached to a black acrylic plate using a HCP highly transparent adhesive transfer sheet 9483PL. The surfaces to be attached are the surface of the polarizer transfer laminate opposite to the release film (the polarizer surface, or the surface of the other layer if another layer is laminated on the polarizer) and the surface of the black acrylic plate. After attachment, the release film is peeled off from the sample, and the 5-degree reflectance at a wavelength of 550 nm is measured using a spectrophotometer (Shimadzu Corporation, UV-3150). The 5-degree reflectance is the reflectance when the incident angle is 5 degrees with respect to the transmission axis direction of the polarizer of the sample.

Reflection-reducing layers include various types of layers such as low-reflection layers, anti-reflection layers, and anti-glare layers.

(Low reflection layer)
The low reflection layer is not particularly limited as long as it is a layer that can reduce the refractive index difference with air, and can be, for example, a low refractive index layer.In the case of the low reflection layer, the upper limit of the reflectance is preferably 5%, more preferably 4%, and even more preferably 3%.The lower limit of the reflectance is preferably 0.8%, and more preferably 1%.

(Anti-Reflection Layer)
The antireflection layer is not particularly limited as long as it is a layer that can prevent reflection by interfering between reflected light at the interface on the viewing side and reflected light at the interface on the image display cell side. Examples of the antireflection layer include a low refractive index layer having a thickness of about the wavelength of visible light (400 to 700 nm)/(refractive index of the low refractive index layer×4).

The anti-reflection layer may be a combination of a low refractive index layer and a high refractive index layer, and in such a combination, it is preferable to place the low refractive index layer on the viewing side (or the release film side). The anti-reflection layer may have two or more low refractive index layers and/or high refractive index layers. Such an anti-reflection layer can further enhance the anti-reflection effect by multiple interference.

In the case of an anti-reflective layer, the upper limit of the reflectance is preferably 2%, more preferably 1.5%, even more preferably 1.2%, and particularly preferably 1%. The lower limit of the reflectance is preferably 0.01%, more preferably 0.1%.

(Low Refractive Index Layer)
The refractive index of the low refractive index layer is preferably 1.45 or less, more preferably 1.42 or less. The refractive index of the low refractive index layer is preferably 1.20 or more, more preferably 1.25 or more. The refractive index of the low refractive index layer is a value measured under the condition of a wavelength of 589 nm.

The thickness of the low refractive index layer is not limited, but may be set appropriately within a range of about 30 nm to 1 μm. If the purpose is to offset the reflection at the interface of the low refractive index layer on the viewing side and the reflection at the interface of the low refractive index layer on the image display cell side to further reduce the reflectance, the thickness of the low refractive index layer is preferably 70 to 120 nm, and more preferably 75 to 110 nm.

Preferred examples of the low refractive index layer include (1) a layer made of a resin composition containing a binder resin and low refractive index particles, (2) a layer made of a fluororesin which is a low refractive index resin, (3) a layer made of a fluororesin composition containing silica or magnesium fluoride, and (4) a thin film of a low refractive index material such as silica or magnesium fluoride.

The binder resin contained in the resin composition (1) may be polyester, polyurethane, polyamide, polycarbonate, acrylic, or the like, without any particular restrictions. Among them, acrylic is preferred, and it is preferable that the binder resin is obtained by polymerizing (crosslinking) a photopolymerizable compound by irradiation with light.

Examples of photopolymerizable compounds include photopolymerizable monomers, photopolymerizable oligomers, and photopolymerizable polymers, which can be adjusted appropriately for use. As the photopolymerizable compound, a combination of a photopolymerizable monomer and a photopolymerizable oligomer or a photopolymerizable polymer is preferred.

(Photopolymerizable Monomer)
The photopolymerizable monomer preferably has a molecular weight of less than 1000. In addition, the photopolymerizable monomer is preferably a polyfunctional monomer having two or more photopolymerizable functional groups (i.e., bifunctional).

Examples of polyfunctional monomers include tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, isocyanuric acid tri(meth)acrylate, isocyanuric acid di(meth)acrylate, polyester tri(meth)acrylate, polyester di(meth)acrylate, bisphenol di(meth)acrylate, diglycerin tetra(meth)acrylate, adamantyl di(meth)acrylate, isobornyl di(meth)acrylate, dicyclopentane di(meth)acrylate, tricyclodecane di(meth)acrylate, and those modified with PO, EO, etc.

Among these, from the viewpoint of obtaining a layer with high hardness, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPPA), etc. are preferred. Only one type of photopolymerizable monomer may be used, or two or more types may be used in combination.

(Photopolymerizable oligomer)
The photopolymerizable oligomer preferably has a weight average molecular weight of 1000 or more and less than 10000. In this specification, the "weight average molecular weight" is a value obtained by dissolving in a solvent such as THF and converting the weight average molecular weight into polystyrene equivalent by a conventionally known gel permeation chromatography (GPC) method. The photopolymerizable oligomer is preferably a polyfunctional oligomer having two or more functionalities. Examples of the polyfunctional oligomer include polyester (meth)acrylate, urethane (meth)acrylate, polyester-urethane (meth)acrylate, polyether (meth)acrylate, polyol (meth)acrylate, melamine (meth)acrylate, isocyanurate (meth)acrylate, and epoxy (meth)acrylate. Only one type of photopolymerizable oligomer may be used, or two or more types may be used in combination.

(Photopolymerizable polymer)
The photopolymerizable polymer preferably has a weight average molecular weight of 10,000 or more, and from the viewpoints of coating suitability and the appearance of the obtained layer, more preferably from 10,000 to 80,000, and even more preferably from 10,000 to 40,000. The photopolymerizable polymer is preferably a multifunctional polymer having two or more functional groups. Examples of the multifunctional polymer include urethane (meth)acrylate, isocyanurate (meth)acrylate, polyester-urethane (meth)acrylate, and epoxy (meth)acrylate. Only one type of photopolymerizable polymer may be used, or two or more types may be used in combination.

(1) Examples of low refractive index particles contained in the resin composition include silica particles (e.g., hollow silica particles), magnesium fluoride particles, etc., and among these, hollow silica particles are preferred. Such hollow silica particles can be produced, for example, by the manufacturing method described in the examples of JP-A-2005-099778.

The average particle size of the primary particles of the low refractive index particles is preferably 5 to 200 nm, more preferably 5 to 100 nm, and even more preferably 10 to 80 nm.

The low refractive index particles are preferably surface-treated with a silane coupling agent, and more preferably surface-treated with a silane coupling agent having a (meth)acryloyl group. Only one type of low refractive index particles may be used, or two or more types may be used in combination.

(1) In addition to the above components, the resin composition may contain a polymerization initiator, a crosslinking agent catalyst, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a leveling agent, a surfactant, etc.

The content of low refractive index particles in the low refractive index layer (or the resin composition (1)) is preferably 10 to 250 parts by mass, more preferably 50 to 200 parts by mass, and even more preferably 100 to 180 parts by mass, per 100 parts by mass of the binder resin.

As the fluorine-based resin (2), a polymerizable compound containing at least a fluorine atom in the molecule or a polymer thereof can be used. The polymerizable compound is not particularly limited, but is preferably, for example, a compound having a curing reactive group such as a photopolymerizable functional group or a thermosetting polar group, or a compound having multiple curing reactive groups at the same time.

As compounds having a photopolymerizable functional group, for example, fluorine-containing monomers having an ethylenically unsaturated bond can be widely used.

It is also preferable to appropriately add a known polysiloxane-based or fluorine-based antifouling agent to the low refractive index layer in order to improve fingerprint resistance. Preferred examples of polysiloxane-based antifouling agents include, for example, polyether-modified polydimethylsiloxane having an acrylic group, polyether-modified dimethylsiloxane, polyester-modified dimethylsiloxane having an acrylic group, polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, and aralkyl-modified polymethylalkylsiloxane. It is preferable that the fluorine-based antifouling agent has a substituent that contributes to the formation of the low refractive index layer or compatibility with the low refractive index layer. The substituent may be one or more, and the multiple substituents may be the same or different from each other. Preferred examples of the substituent include an acryloyl group, a methacryloyl group, a vinyl group, an aryl group, a cinnamoyl group, an epoxy group, an oxetanyl group, a hydroxyl group, a polyoxyalkylene group, a carboxyl group, and an amino group.

(High Refractive Index Layer)
The refractive index of the high refractive index layer is preferably 1.55 to 1.85, and more preferably 1.56 to 1.70, as measured at a wavelength of 589 nm.

The thickness of the high refractive index layer is preferably 30 to 200 nm, and more preferably 50 to 180 nm. The high refractive index layer may be multiple layers, but two or less layers are preferable, and a single layer is more preferable. When the high refractive index layer is composed of multiple layers, it is preferable that the total thickness of the multiple layers is within the above range.

When there are two high refractive index layers, it is preferable that the refractive index of the high refractive index layer on the low refractive index layer side is higher; specifically, it is preferable that the refractive index of the high refractive index layer on the low refractive index layer side is 1.60 to 1.85, and the refractive index of the other high refractive index layer is 1.55 to 1.70.

The high refractive index layer is preferably made of a resin composition containing high refractive index particles and a resin. Preferred high refractive index particles are antimony pentoxide particles (1.79), zinc oxide particles (1.90), titanium oxide particles (2.3 to 2.7), cerium oxide particles (1.95), tin-doped indium oxide particles (1.95 to 2.00), antimony-doped tin oxide particles (1.75 to 1.85), yttrium oxide particles (1.87), zirconium oxide particles (2.10), etc. The numbers in parentheses indicate the refractive index of the material of each particle. Among these, titanium oxide particles and/or zirconium oxide particles are preferred.

Only one type of high refractive index particle may be used, or two or more types may be used in combination. In particular, it is preferable to combine a first high refractive index particle with a second high refractive index particle having a smaller surface charge amount in order to prevent aggregation. In addition, it is also preferable from the standpoint of dispersibility that the high refractive index particles are surface-treated.

The preferred average particle size of the primary particles of the high refractive index particles is the same as that of the low refractive index particles.

The content of high refractive index particles is preferably 30 to 400 parts by mass, more preferably 50 to 200 parts by mass, and even more preferably 80 to 150 parts by mass per 100 parts by mass of resin.

Resins used in the high refractive index layer include the same resins as those listed for the low refractive index layer, except for fluorine-based resins.

The high refractive index layer and the low refractive index layer can be formed, for example, by applying a resin composition containing a photopolymerizable compound to a release film, drying it, and then irradiating the coating-like resin composition with light such as ultraviolet light to polymerize (crosslink) the photopolymerizable compound. When a high refractive index layer and a low refractive index layer are provided on a release film, it is preferable that the release film side be the low refractive index layer.

If necessary, the high refractive index layer and the low refractive index layer (or the resin composition (paint) that constitutes them) may contain thermoplastic resins, thermosetting resins, solvents, polymerization initiators, dispersants, surfactants, antistatic agents, silane coupling agents, thickeners, coloring inhibitors, colorants (pigments, dyes), defoamers, leveling agents, flame retardants, UV absorbers, adhesion promoters, polymerization inhibitors, antioxidants, surface modifiers, lubricants, etc.

(Antiglare Layer)
The antiglare layer is not particularly limited as long as it is a layer capable of causing diffuse reflection by the unevenness of the surface. The antiglare layer can prevent the shape of the light source from being reflected when external light is reflected on the surface and can reduce glare.

On the surface of the antiglare layer, it is preferable that the area where the inclination angle (surface angle) of the antiglare surface is 0.05° or more is 50% or more, more preferably 55% or more, and even more preferably 60% or more. In addition, the upper limit of the percentage of the area where the surface angle is 0.05° or more is preferably 95%, more preferably 90%. When the surface angle is in the above range, it is possible to reduce rainbow spots caused by interference of the antiglare surface itself.

It is preferable that the root mean square slope (RΔq) of the surface of the antiglare layer is 0.004 or less.

The kurtosis (Rku) of the surface of the antiglare layer is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less. Rku is preferably 2 or more.

The surface skewness (RSk) of the antiglare layer is preferably -1.0 to 1.0, more preferably -0.5 to 0.5, and even more preferably -0.3 to 0.3.

The average inclination angle (θa) of the surface irregularities of the antiglare layer is preferably 0.01 to 1.5°, more preferably 0.04 to 1.2°, and even more preferably 0.1 to 0.5°.

The arithmetic mean roughness (Ra) of the surface irregularities of the antiglare layer is preferably 0.02 to 0.25 μm, more preferably 0.02 to 0.15 μm, and even more preferably 0.02 to 0.12 μm.

The ten-point average roughness (Rzjis) of the surface irregularities of the anti-glare layer is preferably 0.15 to 2.00 μm, more preferably 0.20 to 1.20 μm, and even more preferably 0.30 to 0.80 μm.

When the values of RΔq, Rku, RSk, θa, Ra, and Rzjis are equal to or greater than the lower limits, reflection of external light can be suppressed more effectively. When the values of RΔq, Rku, RSk, θa, Ra, and Rzjis are equal to or less than the upper limits, brightness and contrast are excellent.

The average spacing (RSm) of the irregularities on the antiglare surface is preferably 50 to 600 μm, more preferably 100 to 400 μm, even more preferably 120 to 300 μm, and particularly preferably 150 to 280 μm. When the RSm value is equal to or greater than the lower limit, it is easy to control aggregation. When the RSm value is equal to or less than the upper limit, fine details of the image can be reproduced.

RΔq, Rku, RSk, θa, Ra, Rzjis, and RSm are calculated from a roughness curve measured using a contact roughness gauge in accordance with JIS B0601-1994 or JIS B0601-2001.

Methods for providing irregularities on the surface of the anti-glare layer (the surface on the release film side) include, for example, providing irregularities corresponding to the release surface of the release film. Specifically, there are methods such as (1) providing irregularities on the base film of the release film, and (2) providing a layer having irregularities on the base film by coating (or application). In this specification, coating includes not only wet processes in which a paint is applied and solidified, but also dry processes such as deposition, sputtering, and CVD.

Methods for (1) include sandblasting; chemical etching; contacting a release film with a mold having a concave-convex structure; and adding particles to a release film.

Method (2) includes a method in which a base film contains a filler such as particles and a layer having a thickness thinner than the particle size of the filler is provided; a coating material for transferring unevenness (a curable composition, preferably a photocurable composition) is applied to a base film and then brought into contact with a mold having unevenness and cured; a coating material for transferring unevenness (a curable composition, preferably a photocurable composition) is applied to a mold having unevenness and then overlaid on the base film and cured.

The lower limit of the thickness of the antiglare layer is preferably 0.1 μm, more preferably 0.5 μm. The upper limit of the thickness of the antiglare layer is preferably 100 μm, more preferably 50 μm, and even more preferably 20 μm.

The refractive index of the antiglare layer is preferably 1.20 to 1.80, more preferably 1.40 to 1.70. When a low reflection effect is desired by lowering the refractive index of the antiglare layer itself, the refractive index of the antiglare layer is preferably 1.20 to 1.45, more preferably 1.25 to 1.40. When a low refractive index layer and an antiglare layer are combined, particularly when the low refractive index layer and the antiglare layer are laminated in this order on a release film, the refractive index of the antiglare layer is preferably 1.50 to 1.80, more preferably 1.55 to 1.70. The refractive index of the antiglare layer is a value measured at a wavelength of 589 nm.

(Hard Coat Layer)
The hard coat (HC) layer may be appropriately selected from those that are widely used as hard coat layers. The pencil hardness of the hard coat layer is preferably H or more, more preferably 2H or more. The hard coat layer may be provided, for example, by applying and curing a composition (paint for hard coat layer) containing a thermosetting resin or a radiation curing resin.

Examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, urea melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins. Only one type of thermosetting resin may be used, or two or more types may be used in combination. In the composition, a curing agent is added to the curable resin as necessary.

The radiation curable resin is preferably a compound having a radiation curable functional group, and examples of the radiation curable functional group include ethylenically unsaturated bond groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, epoxy groups, and oxetanyl groups. Of these, compounds having an ethylenically unsaturated bond group are preferred, and compounds having two or more ethylenically unsaturated bond groups are more preferred, and polyfunctional (meth)acrylate compounds having two or more ethylenically unsaturated bond groups are even more preferred. The polyfunctional (meth)acrylate compounds may be monomers, oligomers, or polymers.

Specific examples of radiation curable resins include those exemplified as the binder resin in the low refractive index layer. Only one type of radiation curable resin may be used, or two or more types may be used in combination.

In order to achieve the hardness required for a hard coat, the compound having a radiation-curable functional group preferably contains 50% by mass or more of difunctional or higher monomers, more preferably 70% by mass or more. Furthermore, the compound having a radiation-curable functional group preferably contains 50% by mass or more of trifunctional or higher monomers, more preferably 70% by mass or more.

The thickness of the hard coat layer is preferably in the range of 0.1 to 100 μm, and more preferably in the range of 0.8 to 20 μm.

The refractive index of the hard coat layer is more preferably 1.45 to 1.70, and even more preferably 1.50 to 1.60. The refractive index of the hard coat layer is a value measured at a wavelength of 589 nm.

Methods for adjusting the refractive index of the hard coat layer include adjusting the refractive index of the resin, and, when particles are added, adjusting the refractive index of the particles. Specific examples of particles include those exemplified as the particles of the antiglare layer.

The hard coat layer may be a single layer, or it is also preferable to combine it with a reflection-reducing layer or the like. When combining a hard coat layer with a reflection-reducing layer, it is preferable to laminate the reflection-reducing layer and the hard coat layer in this order on a release film. In this specification, the hard coat layer and the reflection-reducing layer are regarded as a single member, and the member may be referred to as the reflection-reducing layer.

(Antistatic Layer)
The antistatic layer is not particularly limited as long as it is a layer containing an antistatic agent.The antistatic agent may be a cationic antistatic agent such as a quaternary ammonium salt; a conductive polymer such as polyaniline or polythiophene; a needle-shaped metal filler; or a conductive high refractive index fine particle such as tin-doped indium oxide fine particles or antimony-doped tin oxide fine particles.The antistatic agent may be used alone or in combination of two or more kinds.

The antistatic layer preferably contains a binder resin in addition to the antistatic agent. Examples of binder resins that can be used include polyester, polyurethane, polyamide, and acrylic. Only one type of binder resin may be used, or two or more types may be used in combination.

An antistatic agent may be added to the hard coat layer so that the hard coat layer functions as an antistatic layer. The antistatic agent to be added to the hard coat layer may be any of the above-mentioned components, such as cationic antistatic agents such as quaternary ammonium salts, fine particles such as tin-doped indium oxide (ITO), conductive polymers, etc.

The content of the antistatic agent is preferably 1 to 30% by mass relative to the total mass of all solids in the antistatic layer (or the hard coat layer if the hard coat layer has an antistatic function).

(Polarizer)
Examples of polarizers (also referred to as polarizing plates, polarizing films, polarizing layers, etc.) that can be used include those in which iodine or an organic dichroic dye is adsorbed onto uniaxially stretched polyvinyl alcohol (PVA) (PVA polarizer), those in which a composition consisting of a liquid crystal compound and a dichroic dye is coated and aligned (liquid crystal polarizer), and wire grid polarizers.

As examples of the method for providing a polarizer on the coating layer, in the case of a PVA polarizer, methods (a) and (b) can be mentioned.
(a) A method of bonding a PVA polarizer alone.
(b) A method of transferring a PVA polarizer on a releasable substrate.

Method (a) includes a method of laminating a single PVA polarizer using an adhesive or pressure-sensitive adhesive, and a method of laminating a PVA polarizer to a coating layer on a release film using an adhesive or pressure-sensitive adhesive is preferred. The thickness of this type of polarizer is preferably 5 to 50 μm, more preferably 10 to 30 μm, and particularly preferably 12 to 25 μm. The thickness of the adhesive or pressure-sensitive adhesive is preferably 1 to 10 μm, and more preferably 2 to 5 μm.

In the method (b), the releasable substrate may be any of those listed as the releasable film, and preferably is an unstretched or uniaxially stretched film such as PET or polypropylene. A method for laminating a PVA polarizer on a releasable substrate may include coating the releasable substrate with PVA, stretching the substrate together with the releasable substrate to adsorb iodine or an organic dichroic dye to the PVA, and then fixing the orientation with a boron compound. In this specification, a laminate of a releasable substrate and a PVA polarizer may be referred to as a "PVA polarizer transfer laminate."

As a transfer method, a method can be mentioned in which the polarizer surface (the surface not laminated with the releasable substrate) of the PVA polarizer transfer laminate is bonded to the coating layer surface of the laminate of the release film and the coating layer with an adhesive or pressure-sensitive adhesive, and the releasable substrate is peeled off as necessary. The thickness of this type of polarizer is preferably 1 to 10 μm, more preferably 2 to 8 μm, and particularly preferably 3 to 6 μm. The thickness of the adhesive or pressure-sensitive adhesive is preferably 1 to 10 μm, and more preferably 2 to 5 μm.

As adhesives for lamination, polyvinyl alcohol adhesives, ultraviolet-curing adhesives such as acrylic and epoxy, and heat-curing adhesives such as epoxy and isocyanate (urethane) are preferably used. The adhesive may also be a hot melt adhesive. Examples of pressure-sensitive adhesives include acrylic, urethane, and rubber-based adhesives. It is also preferable to use an acrylic-based, substrate-less optical transparent pressure-sensitive adhesive sheet as the pressure-sensitive adhesive.

As examples of the method for providing a polarizer on the coating layer, in the case of a liquid crystal polarizer, methods (c) and (d) can be mentioned.
(c) A method of applying a coating material for liquid crystal polarizers.
(d) A method of transferring a liquid crystal polarizer on a releasable substrate.

Method (c) includes a method of applying a liquid crystal polarizer coating containing a liquid crystal compound onto the coating layer, and orienting and fixing the liquid crystal compound. Examples of methods of orienting and fixing the liquid crystal compound include a method of rubbing the coating layer, applying a liquid crystal polarizer coating thereon, heating to orient, and then curing and fixing with ultraviolet light; a method of applying the liquid crystal polarizer coating and then irradiating polarized ultraviolet light to orient and fix the liquid crystal compound. It is also a preferred method to provide an orientation control layer on the coating layer before applying the liquid crystal polarizer coating, i.e., to laminate the liquid crystal polarizer on the coating layer via the orientation control layer.

Method (d) includes a method in which a liquid crystal polarizer is laminated on a releasable substrate in accordance with the above method (c), a coating layer is attached to the liquid crystal polarizer surface using an adhesive or pressure-sensitive adhesive, and the releasable substrate is peeled off as necessary. Examples of adhesives and pressure-sensitive adhesives used in lamination include those mentioned above. The releasable substrate may be one of those listed as the releasable substrate for the PVA polarizer transfer laminate, a metal belt, or the like. In this specification, the laminate of the releasable substrate and the liquid crystal polarizer may be referred to as the "liquid crystal polarizer transfer laminate."

The thickness of the liquid crystal polarizer is preferably 0.1 to 7 μm, more preferably 0.3 to 5 μm, and particularly preferably 0.5 to 3 μm. The thickness of the adhesive or pressure-sensitive adhesive is preferably 1 to 10 μm, and more preferably 2 to 5 μm.

Furthermore, the alignment control layer and the liquid crystal polarizer will be described in detail.
(Orientation Control Layer)
The liquid crystal polarizer coating material may be directly applied to a coating layer or a releasable substrate, but it is also preferable to provide an orientation control layer in advance and then apply the coating material onto the orientation control layer. In this specification, the orientation control layer and the liquid crystal polarizer are regarded as a single member, and the member may be called a liquid crystal polarizer. The liquid crystal polarizer combined with the orientation control layer may be called a liquid crystal polarizing layer in order to clearly distinguish it from the general term liquid crystal polarizer.

The alignment control layer may be any layer that can bring the liquid crystal compound into the desired alignment state. Suitable examples of the alignment control layer include a rubbed alignment control layer, which has a rubbing treatment on the surface, and a photoalignment control layer, which aligns the molecules by irradiating them with polarized light to produce an alignment function.

(Rubbing Treatment Alignment Control Layer)
The material of the rubbing treatment alignment control layer is usually a polymer. As the polymer, polyvinyl alcohol and its derivatives, polyimide and its derivatives, acrylic resin, polysiloxane derivatives, etc. are preferably used. Only one type of polymer may be used, or two or more types may be used in combination.

The method for forming the rubbing treatment alignment control layer preferably includes a step of rubbing the surface of the coating film obtained by applying a coating material for the rubbing treatment alignment control layer containing the above-mentioned polymer and solvent onto the coating layer or the release surface of the releasable substrate. The coating material for the rubbing treatment alignment control layer may contain a crosslinking agent.

As the solvent for the coating material for the rubbing treatment alignment control layer, any solvent that dissolves the polymer material can be used without limitation. Specific examples include alcohols such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, and cellosolve; ester solvents such as ethyl acetate, butyl acetate, and gamma-butyrolactone; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone; aromatic hydrocarbon solvents such as toluene and xylene; and ether solvents such as tetrahydrofuran and dimethoxyethane. Only one type of solvent may be used, or two or more types may be used in combination.

The concentration of the polymer in the coating material for the rubbing treatment alignment control layer can be adjusted as appropriate depending on the type of polymer and the thickness of the alignment control layer to be produced, but it is preferable for the concentration to be 0.2 to 20% by mass, expressed in terms of solids concentration, and a range of 0.3 to 10% by mass is particularly preferable.

As a coating method, known methods can be used, such as coating methods such as gravure coating, die coating, bar coating and applicator methods, and printing methods such as flexography.

After application, it is preferable to dry (e.g., heat-dry). The drying temperature depends on the material of the release film, but in the case of PET, it is preferably 30°C to 170°C, more preferably 50°C to 150°C, and even more preferably 70°C to 130°C. If the drying temperature is within this range, there is no need to take a long drying time, resulting in excellent productivity, no thermal expansion or contraction of the transfer orientation film, the optical function as designed can be achieved, and excellent flatness is also achieved. The drying time is, for example, 0.5 to 30 minutes, more preferably 1 to 20 minutes, and even more preferably 2 to 10 minutes.

The thickness of the rubbing treatment orientation control layer is preferably 0.01 to 10 μm, more preferably 0.05 to 5 μm, and particularly preferably 0.1 μm to 1 μm.

Rubbing can generally be performed by rubbing the surface with paper or cloth in a certain direction. The rubbing is preferably performed using a rubbing roller made of raised fabric made of fibers such as nylon, polyester, or acrylic. When an orientation control layer is provided that orients the film in a specific direction obliquely to the longitudinal direction of the long film, the rubbing direction is preferably set at an angle that matches that direction. The angle can be adjusted by adjusting the angle between the rubbing roller and the film, adjusting the film transport speed and the number of rotations of the roller, etc.

(Photo-Alignment Control Layer)
The photo-alignment control layer is preferably an alignment film in which a coating material for the photo-alignment control layer containing a polymer and/or monomer having a photoreactive group and a solvent is applied to a coating layer or a releasable substrate, and the coating material is irradiated with polarized light, preferably polarized ultraviolet light, to impart an alignment control force. The photoreactive group is preferably a group that generates a liquid crystal alignment ability by irradiation with light, and specifically, it is preferably a group that generates a photoreaction that is the origin of the liquid crystal alignment ability, such as molecular orientation induction or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photodecomposition reaction, which occurs by irradiation with light. Among the photoreactive groups, those that cause a dimerization reaction or a photocrosslinking reaction are preferred in terms of excellent alignment and maintaining the smectic liquid crystal state. As the photoreactive group that can cause the above-mentioned reaction, an unsaturated bond, particularly a double bond, is preferable, and a group having at least one selected from the group consisting of a C=C bond, a C=N bond, an N=N bond, and a C=O bond is particularly preferable.

Examples of photoreactive groups having a C=C bond include vinyl groups, polyene groups, stilbene groups, stilbazolyl groups, stilbazolium groups, chalcone groups, and cinnamoyl groups. Examples of photoreactive groups having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, formazan groups, and groups having azoxybenzene as a basic structure. Examples of photoreactive groups having a C=O bond include benzophenone groups, coumarin groups, anthraquinone groups, and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and halogenated alkyl groups. The number of substituents is not particularly limited, but may be, for example, 1, 2, 3, or 4.

Among these, photoreactive groups capable of causing a photodimerization reaction are preferred, and cinnamoyl and chalcone groups are preferred because the amount of polarized light irradiation required for photoalignment is relatively small, and a photoalignment control layer having excellent thermal stability and stability over time is easily obtained. Furthermore, as a polymer having a photoreactive group, one having a cinnamoyl group such that the terminal of the polymer side chain has a cinnamic acid structure is particularly preferred. Examples of the main chain structure include polyimide, polyamide, (meth)acrylic, and polyester.

Specific examples of the orientation control layer include those described in JP-A-2006-285197, JP-A-2007-76839, JP-A-2007-138138, JP-A-2007-94071, JP-A-2007-121721, JP-A-2007-140465, JP-A-2007-156439, JP-A-2007-133184, and JP-A-2009 Examples of the alignment control layers include those described in JP-A-109831, JP-A-2002-229039, JP-A-2002-265541, JP-A-2002-317013, JP-T-2003-520878, JP-T-2004-529220, JP-A-2013-33248, JP-A-2015-7702, and JP-A-2015-129210.

As the solvent for the paint for the photo-alignment control layer, any solvent that dissolves the polymer and monomer having a photoreactive group can be used without restriction. Specific examples include those mentioned in the method for forming the alignment control layer by rubbing treatment. It is also preferable to add a photopolymerization initiator, a polymerization inhibitor, and various stabilizers to the paint for the photo-alignment control layer. In addition, polymers other than the polymer and monomer having a photoreactive group, and monomers that do not have a photoreactive group and are copolymerizable with the monomer having a photoreactive group may be added to the paint for the photo-alignment control layer.

The concentration of the polymer or monomer of the coating material for the photoalignment control layer, the application method, and the drying conditions can be exemplified by those mentioned in the method for forming the rubbing treatment alignment control layer. The thickness is also the same as the preferred thickness of the rubbing treatment alignment control layer.

It is preferable to irradiate polarized light from the direction of the photo-alignment control layer surface before alignment.

The wavelength of the polarized light is preferably in a wavelength range in which the photoreactive group of the polymer or monomer having the photoreactive group can absorb light energy. Specifically, ultraviolet light with a wavelength in the range of 250 to 400 nm is preferred. Examples of light sources for polarized light include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF, with high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps being preferred.

Polarized light can be obtained, for example, by passing the light from the light source through a polarizer. The direction of polarization can be adjusted by adjusting the polarization angle of the polarizer. Examples of polarizers include polarizing filters, polarizing prisms such as Glan-Thompson and Glan-Taylor, and wire grid type polarizers. It is preferable that the polarized light is substantially parallel light.

By adjusting the angle of the irradiated polarized light, the direction of the alignment control force of the optical alignment control layer can be adjusted as desired.

The irradiation intensity differs depending on the type and amount of the polymerization initiator and resin (monomer), but is preferably 10 to 10,000 mJ/cm ² , more preferably 20 to 5,000 mJ/cm ² , based on 365 nm.

(Liquid Crystal Polarizer)
The liquid crystal polarizer functions as a polarizer that transmits light in only one direction, and preferably contains a dichroic dye.

<Dichroic dye>
The dichroic dye is preferably an organic dye having different absorbance in the long axis direction and in the short axis direction of the molecule.

The dichroic dye preferably has a maximum absorption wavelength (λMAX) in the range of 300 to 700 nm. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes, with azo dyes being preferred. Azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbene azo dyes, with bisazo dyes and/or trisazo dyes being preferred. The dichroic dyes may be used alone or in combination of two or more types, but in order to adjust the color tone (achromatic color), it is preferable to combine two or more types. In particular, it is preferable to combine three or more types. In particular, it is preferable to combine three or more types of azo compounds.

Preferred azo compounds include the dyes described in JP-A-2007-126628, JP-A-2010-168570, JP-A-2013-101328, and JP-A-2013-210624.

It is also preferred that the dichroic dye is a dichroic dye polymer introduced into the side chain of a polymer such as acrylic. Examples of dichroic dye polymers include the polymers listed in JP-A-2016-4055 and polymers obtained by polymerizing the compounds of [Chemical formula 6] to [Chemical formula 12] in JP-A-2014-206682.

From the viewpoint of achieving good orientation of the dichroic dye, the content of the dichroic dye in the liquid crystal polarizer is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, even more preferably 1.0 to 15% by mass, and particularly preferably 2.0 to 10% by mass.

It is preferable that the liquid crystal polarizer further contains a polymerizable liquid crystal compound to improve the film strength, polarization degree, and film uniformity. Note that the polymerizable liquid crystal compound also includes the polymerized film.

<Polymerizable liquid crystal compound>
The polymerizable liquid crystal compound is preferably a compound having a polymerizable group and exhibiting liquid crystallinity. The polymerizable group means a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group means a group capable of undergoing a polymerization reaction by an active radical, an acid, or the like generated from a photopolymerization initiator described later. Examples of the polymerizable group include 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 these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred. The compound exhibiting liquid crystallinity may be a thermotropic liquid crystal or a lyotropic liquid crystal. The thermotropic liquid crystal may be a nematic liquid crystal or a smectic liquid crystal.

As the polymerizable liquid crystal compound, a smectic liquid crystal compound is preferred because it provides higher polarization characteristics, and a higher-order smectic liquid crystal compound is more preferred. If the liquid crystal phase formed by the polymerizable liquid crystal compound is a higher-order smectic phase, a liquid crystal polarizer with a higher degree of orientational order can be produced.

Specific preferred polymerizable liquid crystal compounds include, for example, those described in JP 2002-308832 A, JP 2007-16207 A, JP 2015-163596 A, JP 2007-510946 A, JP 2013-114131 A, WO 2005/045485, and Lub et al. Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996).

From the viewpoint of increasing the orientation of the polymerizable liquid crystal compound, the content of the polymerizable liquid crystal compound in the liquid crystal polarizer is preferably 70 to 99.5% by mass, more preferably 75 to 99% by mass, even more preferably 80 to 97% by mass, and particularly preferably 83 to 95% by mass.

The liquid crystal polarizer can be provided by applying a liquid crystal polarizer paint. The liquid crystal polarizer paint may contain additives such as a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a crosslinking agent, etc. Only one type of additive may be used, or two or more types may be used in combination.

As the solvent, those listed as solvents for the paint for the orientation control layer are preferably used.

The polymerization initiator is not limited as long as it polymerizes the polymerizable liquid crystal compound, but a photopolymerization initiator that generates active radicals by light is preferable. Examples of polymerization initiators include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts, and sulfonium salts.

As the sensitizer, a photosensitizer is preferred, for example, a xanthone compound, an anthracene compound, phenothiazine, rubrene, etc.

Polymerization inhibitors include hydroquinones, catechols, and thiophenols.

As the polymerizable non-liquid crystal compound, one that copolymerizes with the polymerizable liquid crystal compound is preferred. For example, when the polymerizable liquid crystal compound has a (meth)acryloyloxy group, (meth)acrylates can be used. The (meth)acrylates may be monofunctional or polyfunctional. By using polyfunctional (meth)acrylates, the strength of the polarizer can be improved. When a polymerizable non-liquid crystal compound is used, its content in the liquid crystal polarizer is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and particularly preferably 3 to 7% by mass, in order to suppress a decrease in the degree of polarization.

Examples of cross-linking agents include compounds that can react with the functional groups of polymerizable liquid crystal compounds and polymerizable non-liquid crystal compounds, such as isocyanate compounds, melamine, epoxy resins, and oxazoline compounds.

Liquid crystal polarizers can be produced by applying the liquid crystal polarizer paint onto a coating layer, a releasable substrate, or an orientation control layer, and then drying, heating, and curing as necessary.

Coating methods that can be used include known coating methods such as gravure coating, die coating, bar coating, and applicator methods, and printing methods such as flexography.

Drying is preferably carried out in a dryer (such as a hot air dryer or an infrared dryer) at a temperature of 30 to 170°C. The drying temperature is more preferably 50 to 150°C, and even more preferably 70 to 130°C, and the drying time is preferably 0.5 to 30 minutes, more preferably 1 to 20 minutes, and even more preferably 2 to 10 minutes.

Heating can be performed to more firmly align the dichroic dye and polymerizable liquid crystal compound in the liquid crystal polarizer. The heating temperature is preferably set to a temperature range in which the polymerizable liquid crystal compound forms a liquid crystal phase.

When the liquid crystal polarizer coating material contains a polymerizable liquid crystal compound, it is preferable to cure it. Examples of curing methods include heating and light irradiation, with light irradiation being preferred. The dichroic dye can be fixed in an oriented state by curing. Curing is preferably performed in a state in which a liquid crystal phase has been formed in the polymerizable liquid crystal compound, and curing may be performed by irradiating the compound with light at a temperature at which the compound exhibits a liquid crystal phase. Examples of light used in light irradiation include visible light, ultraviolet light, and laser light. Ultraviolet light is preferred in terms of ease of handling.

The irradiation intensity differs depending on the type and amount of the polymerization initiator and resin (monomer), but is preferably 100 to 10,000 mJ/cm ² , more preferably 200 to 5,000 mJ/cm ² , based on 365 nm.

When a liquid crystal polarizer paint is applied onto an orientation control layer, the pigment is oriented along the orientation direction of the orientation layer, resulting in a liquid crystal polarizer with a polarized light transmission axis in a specific direction. However, if no orientation control layer is provided, the liquid crystal polarizer can also be oriented by irradiating it with polarized light to harden the liquid crystal polarizer paint.

Any method may be used to provide a polarizer, but methods (b), (c), and (d) are particularly preferred.

(Retardation Layer)
It is also a preferred embodiment that LP1 has a retardation layer on the opposite side of the coating layer of the polarizer. As the retardation layer, a layer provided between the polarizer and the image display cell for optical compensation in the case of a liquid crystal display device, and a layer (such as a λ/4 retardation layer or a λ/2 retardation layer) for anti-reflection in the case of an organic EL display device or a micro LED display device can be mentioned as a representative example.

The retardation layer is preferably a layer provided by coating a retardation paint, and more preferably a layer provided by coating a paint containing a liquid crystal compound or a polymer compound. The retardation layer can be appropriately selected from positive or negative A plates, positive or negative C plates, O plates, etc. according to the purpose. As the C plate, a plate in which a discotic liquid crystal compound is horizontally aligned (JP Patent Publication 2008-40309), a plate in which a chiral agent is added to a rod-shaped liquid crystal compound to form a twisted helical structure alignment, and a polymer compound layer are preferred, and in particular, a plate in which a discotic liquid crystal compound is horizontally aligned is preferred. As the A plate, a plate in which a rod-shaped liquid crystal compound is horizontally aligned can be mentioned, and the alignment direction (slow axis direction) is preferably parallel to the transmission axis of the polarizer.

Examples of polymeric compounds include polymers such as polyimide, polyamideimide, polyester, polyetherketone, polyaryletherketone, and polyesterimide, which have at least one type of aromatic ring in the repeating unit.

As the liquid crystal compound, a polymerizable liquid crystal compound having a polymerizable group such as a double bond is preferable because it can fix the alignment state. In addition, as the liquid crystal compound, a rod-shaped liquid crystal compound, a discotic liquid crystal compound, etc. can be used.

Examples of rod-shaped liquid crystal compounds include rod-shaped liquid crystal compounds having polymerizable groups described in JP-A-2002-030042, JP-A-2004-204190, JP-A-2005-263789, JP-A-2007-119415, JP-A-2007-186430, and JP-A-11-513360.

Specific examples of rod-shaped liquid crystal compounds include:
CH ₂ =CHCOO-(CH ₂ ) _m -O-Ph1-COO-Ph2-OCO-Ph1-O-(CH ₂ ) _n -OCO-CH=CH ₂
CH ₂ =CHCOO-(CH ₂ ) _m -O-Ph1-COO-NPh-OCO-Ph1-O-(CH ₂ ) _n -OCO-CH=CH ₂
CH ₂ =CHCOO-(CH ₂ ) _m -O-Ph1-COO-Ph2-OCH ₃
CH ₂ =CHCOO-(CH ₂ ) _m -O-Ph1-COO-Ph1-Ph1-CH ₂ CH(CH ₃ )C ₂ H ₅
(Wherein,
m and n are integers from 2 to 6;
Ph1 and Ph2 are 1,4-phenylene groups (Ph2 may be substituted with a methyl group at the 2-position),
NPh is a 2,6-naphthylene group.
Examples include:

These rod-shaped liquid crystal compounds are commercially available from BASF as LC242, etc., and can be used.

Multiple types of these rod-shaped liquid crystal compounds may be used in any combination in any ratio.

Examples of discotic liquid crystal compounds include benzene derivatives, truxene derivatives, cyclohexane derivatives, azacrowns, and phenylacetylene macrocycles. Various discotic liquid crystal compounds are described in JP-A-2001-155866, and these are preferably used.

式中、Ｒ_１～Ｒ_６はそれぞれ独立して水素、ハロゲン、アルキル基、又は－Ｏ－Ｘで示される基（ここで、Ｘは、アルキル基、アシル基、アルコキシベンジル基、エポキシ変性アルコキシベンジル基、アクリロイルオキシ変性アルコキシベンジル基、アクリロイルオキシ変性アルキル基である）である。Ｒ_１～Ｒ_６は、下記一般式（２）で表されるアクリロイルオキシ変性アルコキシベンジル基（ｍは４～１０の整数）であることが好ましい。 Among them, as the discotic liquid crystal compound, a compound having a triphenylene ring represented by the following general formula (1) is preferably used.

In the formula, R ₁ to R ₆ are each independently hydrogen, halogen, an alkyl group, or a group represented by -O-X (wherein X is an alkyl group, an acyl group, an alkoxybenzyl group, an epoxy-modified alkoxybenzyl group, an acryloyloxy-modified alkoxybenzyl group, or an acryloyloxy-modified alkyl group). R ₁ to R ₆ are preferably an acryloyloxy-modified alkoxybenzyl group represented by the following general formula (2) (m is an integer of 4 to 10):

When used as optical compensation for a liquid crystal display device, the degree of retardation is appropriately set depending on the type of liquid crystal cell and the properties of the liquid crystal compound used in the liquid crystal cell. For example, in the case of a TN type, a tilted orientation in which the tilt angle is changed in the thickness direction using discotic liquid crystal is preferably used. In the case of a VA type or an IPS type, a C-plate layer or an A-plate layer using a rod-shaped liquid crystal compound or a discotic liquid crystal compound is preferably used. In addition, in the case of a λ/4 retardation layer and a λ/2 retardation layer, it is preferable to use a rod-shaped compound to form an A-plate layer. These retardation layers may be used as a single layer, or multiple retardation layers may be used in combination.

The method for forming the retardation layer may be a method of applying a paint for the retardation layer onto a polarizer, or a method of transferring the retardation layer (a laminate for transferring the retardation layer) on a releasable substrate to the polarizer. In addition, the polarizer (e.g., a PVA polarizer, a liquid crystal polarizer) and the retardation layer (a laminate for transferring the polarizer and the retardation layer) on the releasable substrate may be transferred to the coat layer. The releasable substrate for the laminate for transferring the retardation layer and the laminate for transferring the polarizer and the retardation layer may be one of those listed as the releasable substrate for the laminate for transferring the PVA polarizer.

The coating material for the retardation layer may contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a crosslinking agent, etc. These can be the same as those described for the alignment control layer or the liquid crystal polarizer.

The method of orienting the liquid crystal compound in the retardation layer can be the same as that for the orientation of the liquid layer polarizer described above. That is, there are a method of directly applying the retardation layer coating material to the polarizer or releasable substrate and irradiating it with polarized ultraviolet light, a method of rubbing the polarizer or releasable substrate, and a method of providing an orientation control layer between the polarizer and the retardation layer. Among these conditions, the conditions described for the orientation control layer or liquid crystal polarizer are preferably used.

A plurality of retardation layers may be provided. In this case, a laminate having a plurality of retardation layers on a single releasable substrate may be used to transfer the plurality of retardation layers to the polarizer. Alternatively, a plurality of laminates having one retardation layer on a single releasable substrate may be used to transfer the retardation layers one by one to the polarizer. The coating method and the transfer method may be combined.

The retardation layer can be selected appropriately depending on the type of image display cell. Below, we will explain the retardation layers used in typical liquid crystal cells.

(Retardation layer for TN type liquid crystal cell)
In a TN type liquid crystal cell, the retardation layer is preferably a layer formed of a discotic liquid crystal compound, and particularly preferably a layer in which the discotic planes of the discotic structural units of the discotic liquid crystal compound are oriented with gradually changing inclination angles in the thickness direction of the retardation layer.

The lower limit of the angle between the disc surface of the discotic structural unit of the discotic liquid crystal compound and the plane of the retardation layer is preferably 5 degrees, more preferably 10 degrees. The upper limit of this angle is preferably 85 degrees, more preferably 80 degrees.

The lower limit of the difference between the minimum and maximum angles between the disc surface of the discotic structural unit of the discotic liquid crystal compound and the plane of the retardation layer is preferably 10 degrees, more preferably 15 degrees. The upper limit of this difference is preferably 60 degrees, more preferably 55 degrees.

It is preferable to adjust the orientation direction of the discotic liquid crystal compound in the planar direction of the retardation layer so that the disc surface of the discotic structure of the discotic liquid crystal compound is upright and parallel to the absorption axis of the polarizer.

The lower limit of the retardation Rth (((nx+ny)/2-nz)×d) in the thickness direction of the retardation layer is preferably 20 nm, more preferably 50 nm, and even more preferably 100 nm. The upper limit of Rth is preferably 400 nm, more preferably 380 nm, and even more preferably 350 nm.

It is preferable that the retardation layer does not have a specific optical axis and has a minimum absolute value of retardation in a direction tilted from the normal direction. The lower limit of the angle between the direction in which the absolute value of retardation is minimum and the normal direction is preferably 5 degrees, more preferably 10 degrees. The upper limit of this angle is preferably 50 degrees, more preferably 40 degrees.

By making the retardation layer have the characteristics described above, it is possible to effectively prevent light leakage and color change when the image display device is viewed from an angle, and to widen the viewing angle.

In general, it is preferable that the absorption axis of a polarizer used in a TN type liquid crystal cell is at 45 degrees to the side of the liquid crystal cell. When the polarizer transfer laminate is wound into a roll, it is preferable, from the viewpoint of convenience of bonding to the liquid crystal cell, that the direction of the absorption axis of the polarizer is at 45 degrees to the longitudinal direction of the rolled polarizer transfer laminate (e.g., the film flow direction or the roll winding direction). In this case, it is preferable that the retardation layer is laminated on the rolled polarizer transfer laminate in accordance with the absorption axis direction of the polarizer.

In such a roll-shaped polarizer transfer laminate with an inclined absorption axis, it is preferable that the polarizer be a liquid crystal polarizer for ease of manufacture.

The polarizer transfer laminate may be prepared by cutting a roll of the polarizer transfer laminate diagonally to the longitudinal direction so that the absorption axis of the polarizer is parallel or perpendicular to the longitudinal direction, and using this to transfer the laminate to a liquid crystal cell.

When retardation layers are provided on the viewing side and the light source side of the liquid crystal cell, the viewing side retardation layer and the light source side retardation layer are not particularly limited as long as they are optically compensated as a whole, and the retardation layers on the viewing side and the light source side do not have to be the same. For example, when the viewing side retardation layer is an inclined alignment layer of discotic liquid crystal, it is also a preferred embodiment that no light source side retardation layer is provided, or that the light source side retardation layer is an A plate layer or a C plate layer, or a composite layer of these. It is also a preferred embodiment that the viewing side retardation layer and the light source side retardation layer are the same retardation layer.

(Retardation layer for VA type liquid crystal cell)
In a VA type liquid crystal cell, the index ellipsoid of the retardation layer is preferably in the shape of a thick disk (eg, anpan-shaped) to an elliptical plate (eg, hamburger-shaped).

The in-plane retardation (Re) of the retardation layer is preferably 0 to 200 nm, and the retardation in the thickness direction (Rth) is preferably 70 to 400 nm, and it is preferable that Re<Rth is satisfied.

The lower limit of Re is more preferably 10 nm, and even more preferably 20 nm. The upper limit of Re is more preferably 100 nm, and even more preferably 70 nm.

The lower limit of Rth is more preferably 100 nm, and even more preferably 120 nm. The upper limit of Rth is more preferably 350 nm, and even more preferably 300 nm, and especially preferably 250 nm.

The lower limit of Rth-Re is preferably 20 nm, more preferably 40 nm, and even more preferably 50 nm. The upper limit is preferably 300 nm, more preferably 250 nm, and even more preferably 200 nm.

By keeping Re, Rth, and the difference (Rth-Re) within the above ranges, it is possible to effectively reduce light leakage due to angles, reduction in gradation, and color tone shifts.

The retardation layer is preferably a retardation layer formed of a discotic liquid crystal compound or a rod-shaped liquid crystal compound. In addition, specific examples of suitable retardation layers include only a C plate layer (e.g., a negative C plate layer), only an A plate layer (e.g., a positive A plate layer), a combination of a C plate layer and an A plate layer, and an orthogonal combination of an A plate layer.

When retardation layers are provided on the viewing side and the light source side of the liquid crystal cell, the viewing side retardation layer and the light source side retardation layer are not particularly limited as long as they are optically compensated as a whole, and the retardation layers on the viewing side and the light source side do not have to be the same. For example, when optical compensation is performed with a combination of an A plate layer and a C plate layer, it is also preferable that the viewing side retardation layer is a combination of an A plate layer and a C plate layer, and no light source side retardation layer is provided, or that the viewing side retardation layer is an A plate and the light source side retardation layer is a C plate layer, or that the viewing side retardation layer is a C plate and the light source side retardation layer is an A plate layer. It is also preferable that the viewing side retardation layer and the light source side retardation layer are the same retardation layer.

It is preferable that the absorption axis of a polarizer (e.g., an absorptive polarizer in the case of a composite polarizer) is parallel or perpendicular to the sides of the liquid crystal cell. It is preferable that the absorption axis of a polarizer (e.g., a roll film) is parallel or perpendicular to the longitudinal direction (e.g., the film flow direction or the roll winding direction).

(Retardation layer for IPS type liquid crystal cell)
In the case of an IPS type liquid crystal cell, it is preferable not to provide a retardation layer, but a retardation layer may be provided. In an IPS type liquid crystal cell, the influence of the liquid crystal compound of the liquid crystal cell is small, but when the display is viewed from an oblique direction, the absorption axis of the light source side polarizer and the absorption axis of the viewing side polarizer are shifted from 90 degrees, causing light leakage. Therefore, when a retardation layer is used, it is preferable that the retardation layer is one that corrects the deviation of this angle.

It is preferable that the absolute value of the Re of the retardation layer is selected from the range of 0 to 360 nm, and the absolute value of the Rth of the retardation layer is selected from the range of 0 to 360 nm, as appropriate according to the design concept. The retardation layer is preferably a combination of a positive C plate and a positive A plate, in which multiple refractive index ellipsoids (e.g., hamburger-shaped ones) are arranged horizontally. It is preferable that nx>nz≧ny or nz>nx>ny in each plate.

It is also preferable to combine multiple retardation layers and stack them in the vertical direction. The retardation layer preferably has at least a positive C plate layer. The Re of the positive C plate layer is preferably -10 to 10 nm, and more preferably -5 to 5 nm. The Rth of the positive C plate layer is preferably -220 to -50 nm, and more preferably -200 to -60 nm. The positive C plate layer is preferably one in which rod-shaped liquid crystal compounds are vertically aligned.

The positive C plate layer is preferably combined with a positive A plate layer. The Re of the positive A plate layer is preferably 50 to 230 nm, more preferably 80 to 220 nm. The Rth of the positive A plate layer is preferably 30 to 150 nm, more preferably 60 to 130 nm. The nz ((nx-nz)/(nx-ny)) of the positive A plate layer is preferably 0.8 to 1.2, more preferably 0.9 to 1.1. The positive A plate layer is preferably made of rod-shaped liquid crystal compounds horizontally aligned, and the alignment direction (slow axis direction) is preferably parallel to the transmission axis of the polarizer.

The order of lamination of the positive C plate layer and the positive A plate layer is not limited, but it is preferable that the positive C plate layer is on the liquid crystal cell side. It is also preferable to use a combination of the positive C plate layer and the positive A plate layer as a retardation layer on the viewing side of the liquid crystal cell, and not provide a retardation layer on the light source side of the liquid crystal cell, but a separate retardation layer may be provided. The positive C plate layer may be used on either the light source side or the viewing side, and the positive A plate layer may be used on the other side. In this case, the optical characteristics can be adjusted as appropriate.

In the case of IPS type liquid crystal cells, as in the case of VA type liquid crystal cells, it is preferable that the absorption axis of the polarizer (e.g., a roll film) is oriented parallel or perpendicular to the longitudinal direction (e.g., the film flow direction or the roll winding direction).

In addition, in the description of the retardation layers for each type of liquid crystal cell above, the angles (45 degrees, parallel, perpendicular) preferably include an error of 5 degrees, more preferably 3 degrees, and even more preferably 2 degrees.

(Organic EL display device)
For the purpose of preventing reflection, the organic EL display device preferably has a circular polarizing plate on the viewing side of the organic EL cell. The retardation layer in the circular polarizing plate is preferably a λ/4 retardation layer. The λ/4 retardation layer will now be described in detail.

(λ/4 Retardation Layer)
The λ/4 retardation layer can convert the linearly polarized light that has passed through the polarizer into circularly polarized light, and convert the circularly polarized light reflected by the wiring in the organic EL cell, the glass substrate, etc., into linearly polarized light that is shifted by 90 degrees from the incident linearly polarized light. The λ/4 retardation layer may be a single layer λ/4 retardation layer, or a composite λ/4 retardation layer of a λ/4 retardation layer and a λ/2 retardation layer. The λ/4 retardation layer may be provided with a C plate layer or the like. In this specification, the single layer retardation layer and the composite λ/4 retardation layer may be collectively referred to as the λ/4 retardation layer.

The in-plane retardation of the λ/4 retardation layer is preferably 100 to 180 nm, more preferably 120 to 150 nm. The in-plane retardation of the λ/2 retardation layer is preferably 200 to 360 nm, more preferably 240 to 300 nm.

(Angle of Slow Axis of λ/4 Retardation Layer)
In the case of a single λ/4 retardation layer, the angle between the alignment axis (slow axis) of the λ/4 retardation layer and the transmission axis of the polarizer is preferably 35 to 55 degrees, more preferably 40 to 50 degrees, and further preferably 42 to 48 degrees.

In the case of a composite λ/4 retardation layer combining a λ/4 retardation layer and a λ/2 retardation layer, it is preferable that the orientation axis (slow axis) of each retardation layer is arranged at an angle such that the phase difference between both layers is λ/4. Specifically, the angle (θ) between the orientation axis (slow axis) of the λ/2 retardation layer and the transmission axis of the polarizer is preferably 5 to 20 degrees, more preferably 7 to 17 degrees. The angle between the orientation axis (slow axis) of the λ/2 retardation layer and the orientation axis (slow axis) of the λ/4 retardation layer is preferably in the range of 2θ+45 degrees±10 degrees, more preferably in the range of 2θ+45 degrees±5 degrees, and even more preferably in the range of 2θ+45 degrees±3 degrees.

Examples of λ/4 phase difference layers can be found in JP 2008-149577 A, JP 2002-303722 A, WO 2006/100830 A, JP 2015-64418 A, JP 2018-10086 A, etc.

Furthermore, in order to reduce changes in color when viewed from an oblique angle, it is also a preferred embodiment to provide a C plate layer on the λ/4 retardation layer. As the C plate layer, a positive or negative C plate layer is selected according to the characteristics of the λ/4 retardation layer and the λ/2 retardation layer.

In the composite λ/4 retardation layer, the λ/4 retardation layer and the λ/2 retardation layer can be laminated, for example, by
a method of providing a λ/2 retardation layer on a polarizer by transfer, and then providing a λ/4 retardation layer thereon by transfer; a method of providing a λ/2 retardation layer on a polarizer by transfer, and then providing a λ/4 retardation layer thereon by coating; a method of providing a λ/2 retardation layer on a polarizer by coating, and then providing a λ/4 retardation layer thereon by transfer; a method of providing a λ/2 retardation layer and a λ/4 retardation layer on a polarizer by coating; and a method of providing a λ/4 retardation layer and a λ/2 retardation layer in this order on a releasable substrate, and then transferring them onto a polarizer.

Various methods can be used to laminate a C plate layer on a λ/4 retardation layer, including a method of transferring the C plate layer onto the λ/4 retardation layer on a polarizer, a method of providing a C plate layer on a release substrate, and then providing a single λ/4 retardation layer or a composite λ/4 retardation layer (λ/2 retardation layer and λ/4 retardation layer) on top of the C plate layer, and then transferring these to a polarizer.

A method for measuring the retardation of the phase difference layer includes, for example, using an automatic birefringence meter (KOBRA series, Oji Measurement Co., Ltd., etc.) to measure the surface of the phase difference layer by tilting it from a position of 0 degrees relative to the normal direction to an in-plane optical axis direction at 10 degree intervals up to 50 degrees, and then inputting the film thickness and average refractive index na into the accompanying software to perform calculations.

As another method, for example, the retardation (R0=Re) is measured from the normal direction using the above-mentioned automatic birefringence meter, and the retardation (R40) is measured by tilting the surface of the retardation layer 40 degrees from the normal direction to the in-plane optical axis direction. From these retardation values, the thickness d of the retardation layer, and the average refractive index na of the retardation layer, nx, ny, and nz are obtained by the following formulas (2), (3), and (4), and Rth can be calculated by substituting these values into formula (1).
Rth=[(nx+ny)/2-nz]×d (1)
R0=(nx-ny)×d (2)
R40=(nx-ny')×d/cos(φ) (3)
(nx+ny+nz)/3=na (4)
In addition,
φ=sin ^-1 [sin (40°)/na]
ny'=ny×nz/[ny ² ×sin ² (φ)+nz ² ×cos ² (φ)] ^1/2

The average refractive index na may be, for example, a value obtained by the following method.
- A value measured with an Abbe refractometer using a thin film slice obtained by irradiating ultraviolet light in an amorphous state after removing the solvent from the paint for the retardation layer. - A value for a retardation layer made of a similar composition or an average value thereof. - A value calculated when Re is measured by orienting the film so that it has an optical axis in the plane, and nx and ny are calculated from the film thickness, and nz is set to the same value as nx (negative A plate) or ny (positive A plate).

Samples for measuring the retardation of the phase difference layer include, for example, a glass film on which a phase difference layer is formed under the same conditions; or a release substrate on which a phase difference layer is formed under the same conditions and then transferred to a glass plate.

(Interlayer Protective Layer)
LP1 may have an interlayer protective layer between any two layers (for example, between the polarizer and the retardation layer, the surface of the retardation layer where the polarizer is not laminated, between a plurality of retardation layers, between an adhesive or pressure-sensitive adhesive and a polarizer or retardation layer). The interlayer protective layer can prevent the components of each layer or the solvent used from migrating to the adjacent layers, causing a decrease in the degree of polarization or a change in the retardation. The interlayer protective layer may be provided on a releasable substrate together with the retardation layer and/or the polarizer and transferred to an object.

Examples of the interlayer protective layer include a transparent resin layer. Examples of transparent resins include, but are not limited to, polyvinyl alcohol, ethylene vinyl alcohol copolymer, polyester, polyurethane, polyamide, polystyrene, acrylic resin, and epoxy resin. The transparent resin may be crosslinked with a crosslinking agent to form a crosslinked structure. It may also be a hard coat made by curing (e.g., photocuring) a curable (e.g., photocurable) composition such as acrylic. In addition, after providing the interlayer protective layer on the alignment film, the interlayer protective layer may be subjected to a rubbing treatment, and a liquid crystal compound alignment layer (liquid crystal polarizer, retardation layer, etc.) may be provided thereon without providing an alignment control layer.

It is preferable that the retardation layer is provided directly on the polarizer or via an interlayer protective layer. Note that providing the retardation layer directly on the polarizer does not only mean that the polarizer and the retardation layer are in contact with each other, but also means that the polarizer and the retardation layer are bonded together with an adhesive or pressure-sensitive adhesive. Examples of the adhesive or pressure-sensitive adhesive used when bonding include those mentioned above.

(Polarizer transfer laminate LP2)
LP2 preferably has a polarizer on a release film. In addition, LP2 preferably has a retardation layer on the side of the polarizer opposite to the release film, and preferably has a coating layer between the release film and the polarizer.

The release film used in LP2 is similar to that described for LP1. The release film used in LP2 may be the same as or different from the release film used in LP1.

The coating layer used in LP2 is similar to that described for LP1. The coating layer used in LP2 may be the same as or different from the coating layer used in LP1.

The polarizer used in LP2 is similar to that described for LP1. The polarizer used in LP2 may be the same as or different from the polarizer used in LP1.

In addition, when LP2 does not have a coating layer between the release film and the polarizer, in the explanation of the method of providing a polarizer and an orientation control layer described in LP1, "coating layer" can be read as "release film" and "coating layer surface of the laminate of release film and coating layer" can be read as "release surface of release film."

The retardation layer used in LP2 is the same as that described for LP1. The retardation layer used in LP2 may be the same as or different from the retardation layer used in LP1.

LP1 and LP2 may have a masking film attached to the surface (polarizer surface or retardation layer surface, etc.) on which the image display cell is laminated in order to protect the surface. As the masking film, a film having an acrylic, rubber, polyolefin, or other adhesive layer on a substrate such as polyethylene, polypropylene, or polyester is preferably used. Instead of the masking film, a releasable substrate used when transferring the polarizer or retardation layer may remain.
The masking film and the releasable substrate are preferably peeled off immediately before bonding to the image display cell or immediately before providing the pressure-sensitive adhesive layer or adhesive layer.
In addition, LP1 and LP2 may be provided with an adhesive layer or pressure-sensitive adhesive layer for bonding an image display cell to the polarizer surface or retardation layer surface, or may be provided with a separator laminated on the adhesive layer or pressure-sensitive adhesive layer. The separator may be any of those listed as the releasable substrates for the PVA polarizer transfer laminate.

It is preferable that LP1 and LP2 do not have a self-supporting film other than the film for the manufacturing process as a constituent layer. Here, the self-supporting film is a film that is manufactured independently. An example of a self-supporting film is a polarizer protective film. A film for the manufacturing process is a member that is used to manufacture a laminate for polarizer transfer but is ultimately removed in the image display device, and examples of such a film include a release film, a release substrate, a masking film, and a separator.

Each layer constituting LP1 and LP2 is preferably applied by coating or transfer. This allows for further reduction in thickness and weight.

(Image display cell and image display device)
Generally, a liquid crystal cell is a liquid crystal display device in which a liquid crystal compound is sealed in a glass plate having electrodes, and an organic EL cell is an organic EL display device in which an organic light-emitting body is sealed in a glass plate having electrodes, etc. In the present invention, such a state before the provision of a polarizing plate is referred to as an image display cell.

Generally, an image display panel is a device in which a polarizing plate is provided in an image display cell and an image can be displayed when a signal is input, and a component such as a touch panel is laminated on this, and an image display device in which an image display panel is incorporated in a housing together with a controller for signals for displaying images is sometimes called an image display device. It is preferable that the image display device of the present invention includes an image display panel, i.e., a device in which an image can be displayed when a signal is input.

(Liquid crystal display device)
The liquid crystal display device is preferably provided with polarizers on both sides of the liquid crystal cell. The polarizer on at least one side of the liquid crystal display panel is preferably the above-mentioned polarizer, and the polarizers on both sides are preferably the above-mentioned polarizer. The order of providing the polarizers on the liquid crystal cell may be the viewing side first or the light source side first, or they may be provided simultaneously.

(LP1 lamination)
The liquid crystal display device preferably has LP1 on the viewing side of the liquid crystal cell. As a method of bonding LP1 to the viewing side of the liquid crystal cell, a method of bonding the viewing side of the liquid crystal cell and the surface of LP1 opposite to the release film (the polarizer surface, or the surface of the other layer when another layer is laminated on the polarizer) using an adhesive or pressure-sensitive adhesive can be mentioned. As the adhesive or pressure-sensitive adhesive, an adhesive or pressure-sensitive adhesive that bonds each layer of LP1 is preferably used. The adhesive or pressure-sensitive adhesive may be provided on LP1 in advance, or may be applied to LP1 or the liquid crystal cell immediately before bonding.

When using adhesive for bonding, it is preferable to cure the adhesive by heating or exposing it to radiation, depending on the type of adhesive.

When laminating, LP1 may be a sheet cut to the required length. Also, when LP1 is a roll film, it may be cut to the required length while unwinding LP1 just before laminating it to the liquid crystal cell or while laminating it. For example, when LP1 is a roll film in which a substrate-less optically transparent adhesive sheet is laminated on a retardation layer, the release layer of the optically transparent adhesive sheet may be peeled off while unwinding LP1 and the edge may be laminated to the liquid crystal cell, or the sheet may be cut to the required length and then laminated to the entire surface, or the sheet may be laminated to the entire surface and then cut to the required length. Cutting may be performed using a blade or laser.

When the LCD display device is a stationary VA type or IPA type, it is preferable to attach LP1 so that the absorption axis of the polarizer is horizontal.

After lamination of LP1, the release film may be peeled off. The release film may be peeled off immediately after lamination, or may be peeled off immediately before or after assembly into the final form in the next process or thereafter to prevent scratches during transportation. In addition, the release film may be peeled off by the final consumer after the image display device has been delivered to the final consumer.

(LP2 lamination)
The liquid crystal display device preferably has LP2 on the light source side of the liquid crystal cell. The bonding method of LP2 may be the same as or different from the bonding method of LP1. However, when the liquid crystal display device is a stationary VA type or IPA type, LP2 is preferably bonded so that the absorption axis of the polarizer is in the vertical direction.

When LP2 has the same layer structure as LP1, a polarizer transfer laminate of LP1 may be used as LP2. However, since the absorption axis direction of the polarizer on the viewing side and the absorption axis direction of the polarizer on the light source side are generally arranged perpendicular to each other in liquid crystal display devices, it is preferable to change the width and length of LP1 and LP2 to match the size of the liquid crystal display cell.

The release film of LP2 may be peeled off in the same manner as LP1, but it is preferable that it be peeled off before assembling into final form.

It is preferable that the liquid crystal display device has a reflective polarizing plate between the light source side polarizer and the light source unit. An example of the reflective polarizing plate is the brightness enhancement film DBEF series sold by 3M. The reflective polarizing plate may be attached to the polarizer surface or the coated surface using an adhesive or pressure sensitive adhesive after peeling off the release film.

(Organic EL display device)
The organic EL display device preferably has LP1 on the viewing side of the organic EL cell.

After laminating the LP1, the release film may be peeled off. The release film may be peeled off immediately after lamination, during the intermediate stage before assembling into the final form, or after assembling into the final form. In addition, the release film may be peeled off by the final consumer after the image display device is delivered to the final consumer.
The organic EL display device may be of a foldable type or a rollable type. The organic EL display device of the present invention can be made thin and has good foldability and rollability.

The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples, and may be modified as appropriate within the scope of the invention. All of these modifications are within the technical scope of the present invention.

The retardation measurements of the phase difference layer in the laminate of the example are as follows.

(Measurement of Retardation of Retardation Layer)
An orientation control layer and a retardation layer were provided on the non-adhesive layer surface of a 50 μm thick polyester film (Cosmoshine (TM) A4100 manufactured by Toyobo Co., Ltd.) under the same conditions as in the examples described below, and this was transferred onto a glass plate (35 mm × 35 mm) to prepare a measurement sample. A UV-curable adhesive was used for the transfer.
The retardation value (Re) of the sample was measured from the vertical direction using an automatic birefringence meter (KOBRA-WR, Oji Measurement Co., Ltd.) at a wavelength of 590 nm. Further, in the case of the retardation layer using the retardation layer coating B, the slow axis in the film plane was set as the tilt axis (rotation axis), and in the case of the retardation layers using the retardation layer coatings A and C, an arbitrary direction in the film plane was set as the tilt axis. The retardation values were similarly measured at angles from 0 degrees to 50 degrees at 10 degree intervals with respect to the normal direction of the film, and Rth was calculated from this value, the thickness, and the average refractive index.
The thickness was determined by embedding the film in epoxy resin, cutting out a cross-sectional piece, and observing it under a polarizing microscope.
The average refractive index was 1.60 in the case of the retardation layers using the paints B and C for the retardation layer, and 1.66 in the case of the retardation layer using the paint A for the retardation layer.

Each layer in the laminate of the embodiment is described below.

(Release film)
The release film was a polyester film (Cosmoshine (TM) A4100 manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm, and the non-adhesive layer side was used as the release surface. The non-release surface was previously subjected to corona treatment to adjust the peel strength.

(Polarizer)
(1) PVA polarizer transfer laminate As a thermoplastic resin substrate, polyethylene terephthalate with an intrinsic viscosity of 0.62 dl/d was melted and kneaded in an extruder, and then extruded onto a cooling roll in the form of a sheet to prepare an unstretched film with a thickness of 100 μm. An aqueous solution of polyvinyl alcohol with a polymerization degree of 2400 and a saponification degree of 99.9 mol% was applied to one side of the unstretched film and dried to form a PVA layer.
The obtained laminate was stretched twice in the longitudinal direction between rolls with different peripheral speeds at 120° C. and taken up. Next, the obtained laminate was treated with a 4% aqueous boric acid solution for 30 seconds, and then immersed in a mixed aqueous solution of iodine (0.2%) and potassium iodide (1%) for 60 seconds to be dyed, and subsequently treated with a mixed aqueous solution of potassium iodide (3%) and boric acid (3%) for 30 seconds.
Further, this laminate was uniaxially stretched in the longitudinal direction in a mixed aqueous solution of boric acid (4%) and potassium iodide (5%) at 72°C, subsequently washed with a 4% aqueous solution of potassium iodide, the aqueous solution was removed with an air knife, and then dried in an oven at 80°C. Both ends were slit and wound up to obtain a PVA polarizer transfer laminate with a width of 50 cm and a length of 1000 m. The total stretching ratio was 6.5 times, and the thickness of the PVA polarizer was 5 μm. The thickness was measured by embedding the PVA polarizer transfer laminate in epoxy resin, cutting out a slice, and observing it with an optical microscope. This PVA polarizer is labeled as PVA (transfer) in Table 1.

特開昭６３－３０１８５０号公報の実施例１に準じて下記色素（ｆ）を合成した。

特公平５－４９７１０号公報の実施例２に準じて下記色素（ｇ）を合成した。

特公昭６３－１３５７号公報の一般式（１）の化合物の製造方法に準じて下記色素（ｈ）を合成した。

(2) Liquid Crystal Polarizer The following compounds (d) and (e) were synthesized according to the description in paragraph [0134] of JP-A-2007-510946 and Lub et al., Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996).

The following dye (f) was synthesized according to Example 1 of JP-A-63-301850.

The following dye (g) was synthesized according to Example 2 of JP-B-5-49710.

The following dye (h) was synthesized according to the method for producing the compound of formula (1) described in JP-B-63-1357.

75 parts by weight of (d), 25 parts by weight of (e), 2.5 parts by weight of (f), 2.5 parts by weight of (g), 2.5 parts by weight of (h), 6 parts by weight of IRGACURE (trademark) 369E (manufactured by BASF), and 250 parts by weight of orthoxylen were mixed and dissolved to prepare a coating material for liquid crystal polarizers. The liquid crystal polarizer obtained by coating this coating material is labeled as liquid crystal coating in Table 1.

Example 1
A coating material for a low refractive index layer was applied to the corona-treated surface of a release film having a width of 50 cm, and the coating material was dried in an oven at 90° C. to evaporate the solvent, followed by irradiation with ultraviolet light to form a low refractive index layer having a thickness of 0.5 μm. A coating material for a hard coat layer was further applied on the low refractive index layer, and the coating material was dried in an oven at 90° C. to evaporate the solvent, followed by irradiation with ultraviolet light to form a hard coat layer having a thickness of 3 μm. Subsequently, an acrylic ultraviolet-curing adhesive was applied to the hard coat layer surface, which was then superimposed on the polarizer surface (PVA surface) of the PVA polarizer transfer laminate, and ultraviolet light was irradiated from the release film surface to cure the adhesive, thereby obtaining a polarizer transfer laminate (LPPVA0). The film was wound into a roll film having a length of 1000 m.

Example 2
The polarizer transfer laminate (LPPVA0) obtained in Example 1 was cut to a length of 70 cm, the thermoplastic resin substrate was peeled off, and the coating material for the orientation control layer was applied to this surface, dried at 100°C, and an orientation control layer with a thickness of 0.5 μm was provided. The orientation control layer was further treated with a rubbing roll wrapped with a nylon napped cloth. The rubbing direction was in the flow direction of the film. Subsequently, the coating material A for the retardation layer was applied to the rubbed surface, and then heated at 125°C for 3 minutes to evaporate the solvent and align the discotic liquid crystal compound. Subsequently, ultraviolet light was irradiated for 30 seconds in an environment of 80°C to obtain a polarizer transfer laminate (LPPVA1).

Example 3
An alignment control layer was provided in the same manner as in Example 2, and the alignment control layer was treated with a rubbing roll wrapped with a nylon napped cloth. The rubbing direction was perpendicular to the flow direction of the film. Subsequently, the retardation layer coating material B was applied, and the film was heated at 110°C for 3 minutes to evaporate the solvent and align the rod-shaped liquid crystal compound. Furthermore, the film was irradiated with ultraviolet light for 30 seconds in an environment of 110°C to obtain a laminate for polarizer transfer (LPPVA2).

Example 4
A laminate for polarizer transfer (LPPVA3) was obtained in the same manner as in Example 3, except that the rubbing direction for the orientation control layer was set at 45 degrees to the flow direction of the film.

Example 5
(Preparation of Laminate for Transferring Retardation Layer)
As the release substrate, a polyester film (Cosmoshine (TM) A4100 manufactured by Toyobo Co., Ltd.) having a width of 50 cm and a thickness of 38 μm was used. The coating material for the orientation control layer was applied to the non-adhesive layer surface of the release substrate, and dried at 100 ° C. to provide an orientation control layer having a thickness of 0.5 μm. The orientation control layer was then treated with a rubbing roll wrapped with a nylon napped cloth. The film was slanted on the rubbing roll, and the direction of the rubbing roll, the running speed of the film, and the number of revolutions of the rubbing roll were adjusted so that the rubbing direction was 45 degrees to the flow direction of the film. Subsequently, the coating material B for the retardation layer was applied, and the film was heated at 110 ° C. for 3 minutes to evaporate the solvent and align the rod-shaped liquid crystal compound. The film was then irradiated with ultraviolet light for 30 seconds in an environment of 110 ° C. to obtain a retardation layer transfer laminate having a length of 200 m.

The polarizer transfer laminate (LPPVA0) obtained in Example 1 and the above-mentioned retardation layer transfer laminate were unwound, and the polarizer surface of LPPVA0 and the retardation layer surface of the retardation layer transfer laminate were bonded together using a UV-curable adhesive and then wound up to obtain a polarizer transfer laminate (LPPVA4) having a length of 200 m.

Example 6
A coating material for a low refractive index layer was applied to the corona-treated surface of the release film, and the coating material was dried in an oven at 90° C. to evaporate the solvent, followed by irradiation with ultraviolet light to form a low refractive index layer having a thickness of 86 nm. Further, a coating material for a high refractive index layer was applied on the low refractive index layer, and the coating material was dried in an oven at 90° C. to evaporate the solvent, followed by irradiation with ultraviolet light to form a high refractive index layer having a thickness of 130 nm. The thickness was measured using an ellipsometer (manufactured by Horiba, Ltd., automatic thin film measuring device Smart SE). Subsequently, a hard coat layer and a polarizer were provided in the same manner as in Example 1 to obtain a laminate for polarizer transfer. Furthermore, a retardation layer was provided in the same manner as in Example 4 to obtain a laminate for polarizer transfer (LPPVA5).

(Example 7)
The coating material for unevenness transfer was applied to one side of a 50 cm wide polyester film (Cosmoshine (TM) A4300 manufactured by Toyobo Co., Ltd.) and then heated and cured at 160°C for 3 minutes to provide a cured film with a coating amount of 1.0 g/ ^m2 . The cured film had an uneven surface structure (Ra 0.7 μm) derived from particles.

A low refractive index layer, a hard coat layer and a polarizer were provided on the cured film surface in the same manner as in Example 1, except that the film having this obtained cured film was used as a release film, and a laminate for polarizer transfer (LPPVA6) was obtained.

(Example 8)
On the retardation layer of the polarizer transfer laminate (LPPVA2) obtained in Example 3, a coating material for an interlayer protective coating layer was applied and dried, and then an interlayer protective coating layer having a dry thickness of 0.5 μm was provided by irradiating with ultraviolet light. Subsequently, a coating material C for a retardation layer was applied and dried, and then irradiated with ultraviolet light at 38° C. for 80 seconds to obtain a retardation layer in which the liquid crystal compound was vertically aligned.

(Example 9)
The film having the low refractive index layer and the hard coat layer laminated thereon produced in Example 1 was cut to a length of 70 cm, the hard coat layer surface was rubbed in the long side direction, and the coating material for liquid crystal polarizing film was applied to the rubbed surface. Further, it was dried at 110° C. for 3 minutes to form a film having a thickness of 2 μm, and then irradiated with ultraviolet light to obtain a laminate for polarizer transfer (LPLC0).

(Example 10)
A polarizer transfer laminate (LPLC1) was obtained in the same manner as in Example 3, except that the polarizer transfer laminate (LPLC0) obtained in Example 9 was used instead of the polarizer transfer laminate (LPPVA0) and the rubbing direction of the orientation control layer was set at 45 degrees with respect to the flow direction of the film.

Example 11
An orientation control layer was provided in the same manner as in Example 10, and the liquid crystal retardation layer coating solution D was applied onto the orientation control layer that had been subjected to rubbing treatment, and the liquid crystal was further heated for 3 minutes after drying at 120° C. to mature the liquid crystal and align the discotic compound. Subsequently, the coating layer was cured by irradiating ultraviolet rays, and a retardation layer having a thickness of 1.8 μm was produced, thereby obtaining a laminate for polarizer transfer (LPLC2).

Example 12
A polarizer transfer laminate (LPLC3) was obtained in the same manner as in Example 10, except that the film having a low refractive index layer, a high refractive index layer, and a hard coat layer prepared in Example 6 was used instead of the film having a low refractive index layer and a hard coat layer prepared in Example 1.

The layer structures of Examples 1 to 12 are shown in Table 1.

(Evaluation on a liquid crystal display device)
The viewing side polarizing plate and the light source side polarizing plate of the liquid crystal display cell of each type (IPS, VA, TN) on the market were peeled off, and instead, the laminate for polarizer transfer was cut to the size of the liquid crystal display cell, and laminated using an optical adhesive, and then the release film of the laminate for polarizer transfer was peeled off. The lamination was performed so that the absorption axis of the polarizing plate of the original liquid crystal display device and the absorption axis of the laminate for polarizer transfer were in the same direction. In addition, the release substrate of the laminate for retardation layer transfer of LPPVA4 was peeled off immediately before laminating it with the liquid crystal cell.

(Image displayability)
When landscape pictures were displayed on the liquid crystal display device and the display state of the image was observed from the front, all images displayed were of the same quality as those on the original display device.

(Viewing angle characteristics)
The image was observed by moving from the front in each direction, up and down, left and right, upper right, and lower right. In the IPS and VA type liquid crystal cells, the viewing angle was improved when compared with the case where LPPVA0 was used on both the viewing side and the light source side, and in the TN type liquid crystal cell, the viewing angle was improved when compared with the case where LPPVA0 was used on both the viewing side and the light source side, and the viewing angle was improved when compared with the case where LPPVA0 was used on both the viewing side and the light source side.

(Reflection)
The liquid crystal display device was tilted at an angle of about 45 degrees from the normal direction so that the fluorescent light in the room was reflected. A polyester film (Cosmoshine (TM) A4100 manufactured by Toyobo Co., Ltd.) with a thickness of 50 μm was placed on the liquid crystal display device with the non-easy adhesion layer side facing up, and all of the reflections were less than those of the polyester film side.

(Scratch resistance)
The liquid crystal display screen was rubbed back and forth with steel wool 50 times, and then peeling of the polarizer was observed. However, no peeling of the polarizer was observed, and the scratch resistance was also excellent.

Table 2 shows a summary of the evaluation results for the liquid crystal display device.

(Evaluation on an organic EL display device)
The circular polarizing plate of a commercially available organic EL display device was peeled off, and instead, a laminate for polarizer transfer was cut to the size of a liquid crystal display cell, and laminated using an optical pressure-sensitive adhesive, and then the release film of the laminate for polarizer transfer was peeled off. The lamination was performed so that the absorption axis of the circular polarizing plate of the original display device and the absorption axis of the laminate for polarizer transfer were in the same direction.

(Anti-reflection)
When the screens were observed indoors with a fluorescent light behind them to check the anti-reflection effect, it was found that all of the screens had the same anti-reflection effect as the original organic EL display device.

(Reflection)
The organic EL display device was tilted at an angle of about 45 degrees from the normal direction so that the fluorescent light in the room was reflected. A polyester film (Cosmoshine (TM) A4100 manufactured by Toyobo Co., Ltd.) with a thickness of 50 μm was placed on the organic EL display device with the non-easy adhesion layer side facing up, and all reflections were less than those of the polyester film side.

(Scratch resistance)
The organic EL display screen was rubbed back and forth with steel wool 50 times, and then peeling of the polarizer was observed. However, no peeling of the polarizer was observed, and the screen was also excellent in terms of scratch resistance.

Table 3 shows a summary of the evaluation results for the organic EL display device.

Claims (9)

A method for producing an image display device, comprising: laminating a polarizer transfer laminate LP1, which is a laminate including a coating layer and a polarizer laminated in this order on a release film, on at least one surface of an image display cell such that the polarizer of the polarizer transfer laminate LP1 is disposed on the image display cell side,
The coating layer is applied to the release surface of the release film,
the polarizer is a PVA polarizer or a liquid crystal polarizer,
In the case where the polarizer is a PVA polarizer, the polarizer is provided on the coating layer by either of the following (a) and ( b ) :
In the method for producing an image display device as described above , when the polarizer is a liquid crystal polarizer, the polarizer is provided on the coating layer by either of the following (c) and (d):
(a) A method of bonding the PVA polarizer alone to the coating layer on the release film using an adhesive or pressure-sensitive adhesive; (b) A method of bonding the PVA polarizer on a releasable substrate and the coating layer surface of a laminate of the release film and the coating layer with an adhesive or pressure-sensitive adhesive, and then peeling off the release substrate to transfer the PVA polarizer; (c) A liquid crystal polarizer coating material containing a liquid crystal compound is applied to the coating layer on the release film to orient and fix the liquid crystal compound; (d) A method of bonding the coating layer surface of the release film and the coating layer laminate to the liquid crystal polarizer surface on a release substrate using an adhesive or pressure-sensitive adhesive, and then peeling off the release substrate to transfer the liquid crystal polarizer. A method for manufacturing an image display device, comprising: (A) a step of laminating a polarizer transfer laminate LP1, in which a coating layer and a polarizer are laminated in this order on a release film, on one surface of an image display cell, such that the polarizer of the polarizer transfer laminate LP1 is disposed on the image display cell side; and (B) a step of laminating a polarizer transfer laminate LP2, in which a polarizer is laminated on a release film, on the other surface of the image display cell, such that the polarizer of the polarizer transfer laminate LP2 is disposed on the image display cell side,
The coating layer of the polarizer transfer laminate LP1 is provided by coating on the release surface of the release film,
The polarizer of the polarizer transfer laminate LP1 is a PVA polarizer or a liquid crystal polarizer,
In the case where the polarizer of the polarizer transfer laminate LP1 is the PVA polarizer, the polarizer is provided on the coating layer by any one of the following (a) and ( b ) :
The method for manufacturing an image display device, wherein, when the polarizer of the polarizer transfer laminate LP1 is a liquid crystal polarizer, the polarizer is provided on the coating layer by either (c) or (d) below .
(a) A method of bonding the PVA polarizer alone to the coating layer on the release film using an adhesive or pressure-sensitive adhesive; (b) A method of bonding the PVA polarizer on a releasable substrate and the coating layer surface of a laminate of the release film and the coating layer with an adhesive or pressure-sensitive adhesive, and then peeling off the release substrate to transfer the PVA polarizer; (c) A liquid crystal polarizer coating material containing a liquid crystal compound is applied to the coating layer on the release film to orient and fix the liquid crystal compound; (d) A method of bonding the coating layer surface of the release film and the coating layer laminate to the liquid crystal polarizer surface on a release substrate using an adhesive or pressure-sensitive adhesive, and then peeling off the release substrate to transfer the liquid crystal polarizer. The method for producing an image display device according to claim 1 , wherein the polarizer transfer laminate LP1 has a retardation layer on a side of the polarizer opposite to the coating layer. The method for producing an image display device according to claim 2 , wherein the polarizer transfer laminate LP2 has a retardation layer on a side of the polarizer opposite to the release film. 5. The method for producing an image display device according to claim 2, wherein the polarizer transfer laminate LP2 has a coating layer between the release film and the polarizer . The method for producing an image display device according to any one of claims 1 to 5, wherein the coating layer of the polarizer transfer laminate LP1 includes any one of a hard coating layer, a reflection reducing layer, and an antistatic layer. The method for manufacturing an image display device according to any one of claims 1 to 6, wherein the polarizer transfer laminate LP1 does not have a self-supporting polarizer protective film. 8. The method for producing an image display device according to claim 1, wherein the image display cell is a liquid crystal display cell. 8. The method for manufacturing an image display device according to claim 1, wherein the image display cell is an organic EL display cell.