CN117471597A

CN117471597A - Polarizing plate and image display device

Info

Publication number: CN117471597A
Application number: CN202310927756.XA
Authority: CN
Inventors: 铃木宏昌; 祖父江彰二
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2022-07-29
Filing date: 2023-07-26
Publication date: 2024-01-30
Also published as: JP7361849B1; JP2024019156A; JP2024018519A; KR20240016903A

Abstract

The present invention provides a polarizing plate and an image display device, wherein the polarizing plate is provided with a phase difference plate, the phase difference plate is provided with a plurality of phase difference layers containing a solidified product of a liquid crystal compound, and the durability of the polarizing plate to external force is excellent. The polarizing plate is formed by laminating a linear polarizing plate, a 1 st lamination layer and a phase difference plate in order, wherein the phase difference plate comprises a 1 st phase difference layer and a 2 nd phase difference layer, the 1 st phase difference layer and the 2 nd phase difference layer comprise cured products of liquid crystal compounds, the peel strength between the 1 st phase difference layer and the 2 nd phase difference layer is less than 1.0N/25mm, and the 1 st lamination layer comprises an adhesive with a tensile storage modulus of less than 10MPa at a temperature of 23 ℃.

Description

Polarizing plate and image display device

Technical Field

The present invention relates to a polarizing plate and an image display device.

Background

Conventionally, in an image display device, a method of arranging a circular polarizing plate on the viewing side of an image display panel to suppress a decrease in visibility due to reflection of external light has been adopted.

The circularly polarizing plate is formed by laminating a linear polarizing plate and a phase difference plate. In the circularly polarizing plate, external light directed to the image display panel is converted into linearly polarized light by the linearly polarizing plate, and then into circularly polarized light by the following phase difference plate. Although external light, which is circularly polarized light, is reflected on the surface of the image display panel, the direction of rotation of the polarization plane is reversed during the reflection, and the external light is converted into linearly polarized light by the phase difference plate, and then is blocked by the subsequent linear polarization plate. As a result, the emission of the external light to the outside is significantly suppressed.

In the retardation plate, a structure having a retardation layer containing a cured product of a liquid crystal compound is known (for example, patent documents 1 and 2). According to this structure, the thickness of the retardation plate can be reduced.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2015-163935

Patent document 2: japanese patent application laid-open No. 2019-91030

Disclosure of Invention

Problems to be solved by the invention

In a retardation plate having a plurality of retardation layers containing a cured product of a liquid crystal compound, if the retardation plate is preferably thinned, durability against external force is reduced, and there is a case where a problem such as peeling occurs between retardation layers.

The purpose of the present invention is to provide a polarizing plate that is provided with a phase difference plate having a plurality of phase difference layers that contain a cured product of a liquid crystal compound, and that has excellent durability to external forces.

Means for solving the problems

The present invention provides the following polarizing plate.

A polarizing plate comprising a linear polarizing plate, a 1 st lamination layer and a phase difference plate laminated in this order,

the phase difference plate has a 1 st phase difference layer and a 2 nd phase difference layer,

the 1 st phase difference layer and the 2 nd phase difference layer contain cured products of liquid crystal compounds,

The peel strength between the 1 st retardation layer and the 2 nd retardation layer is 1.0N/25mm or less,

the 1 st adhesive layer contains an adhesive having a tensile storage modulus (Japanese patent application No. , storage modulus) of 10MPa or less at a temperature of 23 ℃.

The polarizing plate according to [ 2 ], wherein the retardation plate has only an alignment film or no other layer interposed between the 1 st retardation layer and the 2 nd retardation layer.

The polarizing plate according to [ 1 ] or [ 2 ], wherein the linear polarizing plate has a polarizing plate,

the thickness of the polarizing plate is 15 μm or less.

The polarizing plate according to item [ 4 ], wherein the linear polarizing plate has a protective film provided on a surface of the polarizing plate opposite to the 1 st adhesive layer,

the thickness of the protective film is 30 μm or less.

The polarizing plate according to any one of [ 1 ] to [ 4 ], wherein the 1 st retardation layer is a lambda/4 layer having inverse dispersibility.

The polarizing plate according to any one of [ 1 ] to [ 5 ], wherein the 2 nd retardation layer is a positive C plate.

Effects of the invention

According to the present invention, a polarizing plate excellent in durability against external force can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view schematically showing an example of a polarizing plate according to the present embodiment.

Fig. 2 is a schematic cross-sectional view schematically showing a specific example of the phase difference plate.

Fig. 3 is a schematic cross-sectional view schematically showing a specific example of the phase difference plate.

Fig. 4 is a schematic cross-sectional view schematically showing an example of the image display device according to the present embodiment.

Description of the reference numerals

1: polarizing plate, 2: image display apparatus, 10: linear polarizing plate, 21: lamination layer 1, 30: phase difference plate, 31: 1 st phase difference layer, 32: 2 nd retardation layer, 40: an image display panel.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all the drawings below, the scale of each component shown in the drawings is not necessarily identical to the scale of the actual component, and is appropriately adjusted to facilitate understanding of the components.

[ polarizing plate ]

Fig. 1 is a schematic cross-sectional view schematically showing an example of a polarizing plate according to the present embodiment. As shown in fig. 1, the polarizing plate 1 includes a linear polarizing plate 10, a 1 st adhesive layer 21, and a phase difference plate 30 laminated in this order from the front surface side. The retardation plate 30 has a 1 st retardation layer 31 and a 2 nd retardation layer 32. The polarizing plate 1 may be a circular polarizing plate. In the present specification, the term polarizing plate also includes a circular polarizing plate.

The peel strength between the 1 st retardation layer 31 and the 2 nd retardation layer 32 of the retardation plate 30 may be 1.0N/25mm or less, or may be 0.8N/25mm or less. The peel strength was measured by the method described in the adhesion evaluation 1 shown in the examples. The present invention also includes a retardation plate 30 having a peel strength reduced by a storage environment or a use environment, and having a peel strength exceeding 1.0N/25mm immediately after production, but thereafter having a peel strength of 1.0N/25mm or less. The peel strength between the 1 st retardation layer 31 and the 2 nd retardation layer 32 of the retardation plate 30 is preferably 0.2N/25mm or more, more preferably 0.4N/25mm or more. The peel strength is preferably 0.1N/25mm or more, more preferably 0.2N/25mm or more, after being lowered by the storage environment and the use environment. In the retardation plate 30, other layers may be interposed between the 1 st retardation layer 31 and the 2 nd retardation layer 32, or other layers may be not interposed therebetween, and in either case, the peel strength between the 1 st retardation layer 31 and the 2 nd retardation layer 32 means a strength required to separate the 1 st retardation layer 31 and the 2 nd retardation layer 32 therebetween.

In the retardation plate 30, when the 1 st retardation layer 31 and the 2 nd retardation layer 32 are bonded via a bonding layer (hereinafter referred to as "3 rd bonding layer"), the peel strength of the 1 st retardation layer 31 and the 2 nd retardation layer 32 greatly depends on the bonding force of the 3 rd bonding layer. The bonding force of the 3 rd bonding layer greatly depends on the material of the 3 rd bonding layer, and depending on the bonding force of the 3 rd bonding layer, the peel strength between the 1 st retardation layer 31 and the 2 nd retardation layer 32 may be 1.0N/25mm or less. In general, the adhesive has a lower adhesion force than the adhesive, and when the 3 rd adhesive layer is formed of the adhesive, the peel strength between the 1 st retardation layer 31 and the 2 nd retardation layer 32 is easily 1.0N/25mm or less. In the retardation plate 30, when the 1 st retardation layer 31 and the 2 nd retardation layer 32 are laminated without an intervening lamination layer, the peel strength of the 1 st retardation layer 31 and the 2 nd retardation layer 32 is usually low, and is usually 1.0N/25mm or less. The retardation plate 30 has a structure in which the 1 st retardation layer 31 and the 2 nd retardation layer 32 are laminated without a lamination layer, and may have an alignment film alone or a structure in which other layers are not interposed between the 1 st retardation layer 31 and the 2 nd retardation layer 32. The 3 rd bonding layer interposed between the 1 st phase difference layer 31 and the 2 nd phase difference layer 32 is preferably an adhesive from the viewpoint of thickness reduction, and is preferably a laminate without the 3 rd bonding layer from the viewpoint of thickness reduction.

The present inventors have found that: the polarizing plate using the retardation plate having low peel strength between the 1 st retardation layer 31 and the 2 nd retardation layer 32 has low durability against external force. The present inventors have further conducted intensive studies and have found the following findings, thereby completing the present invention: even in the case of a polarizing plate using a retardation plate having a peel strength of 1.0N/25mm or less between the 1 st retardation layer 31 and the 2 nd retardation layer 32, the 1 st adhesive layer 21 interposed between the linear polarizing plate 10 and the retardation plate 30 can be made to have an adhesive having a tensile storage modulus of 10MPa or less at a temperature of 23 ℃. The tensile storage modulus of the adhesive agent forming the 1 st adhesive layer 21 at a temperature of 23 ℃ is preferably 8MPa or less, more preferably 5MPa or less, further preferably 1MPa or less, and may be 0.7MPa or less, preferably 0.02MPa or more, further preferably 0.1MPa or more. The polarizing plate of the present invention has high durability against external forces, and examples of external forces include external forces applied in the cross-cut test in examples, external forces applied due to dropping, external forces applied due to peeling of the protective film in the manufacturing process, and the like.

Here, the term "storage modulus" (dynamic elastic modulus) is a term of viscoelastic measurement which is generally used, and is a value obtained by a method (dynamic viscoelastic measurement) of measuring the mechanical properties of a sample by applying strain or stress which changes (vibrates) with time to the sample and measuring the stress or strain generated thereby, and is an elastic modulus which is in phase with vibration stress when the strain is divided into waves of 2 components which are components in phase with stress and components which are shifted by 90 degrees from each other. Storage modulus is referred to as tensile storage modulus when the stress application method is a tensile mode and as shear storage modulus when the stress application method is a shear mode, depending on the stress application method. The relationship between the tensile storage modulus and the shear storage modulus is generally represented by the following formula (10) and can be converted (see book name "lecture/rheology" (editor: japanese rheology society, issuer: west Kogyo, issuer: high molecular Co., ltd.) (1.12) on page 15)).

E=gx2× (1+v) formula (10)

Here, E is the tensile storage modulus, G is the shear storage modulus, and v is the poisson's ratio.

The tensile storage modulus can be measured by using a commercially available viscoelasticity measuring apparatus, for example, a dynamic viscoelasticity measuring apparatus "DVA-220" manufactured by IT meter control Co., ltd. Shown in examples described later, and the shear storage modulus can be measured by using a viscoelasticity measuring apparatus "MCR-301" manufactured by Anton Paar Co., ltd. In the temperature control of these viscoelasticity measuring apparatuses, various known temperature control devices such as a circulation thermostatic bath, an electric heater, and a peltier element are used, and thus the temperature at the time of measurement can be set.

[ 1 st adhesive layer ]

The 1 st bonding layer 21 is a layer that performs bonding between the linear polarizing plate 10 and the retardation plate 30. Examples of the adhesive binder having a tensile storage modulus of 10MPa or less at a temperature of 23 ℃ include adhesives and binders. As the 1 st lamination layer 21, an adhesive is preferably used. The present inventors have found that durability against external force can be improved by using an adhesive agent having a tensile storage modulus of 10MPa or less as the 1 st lamination layer 21.

The specific adhesive used for the 1 st adhesive layer 21 may be, for example, an adhesive based on an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyether, or the like. Among them, a material which is excellent in optical transparency, maintains moderate wettability and cohesion, is excellent in adhesion to a substrate, and further has weather resistance, heat resistance, etc., and does not cause peeling problems such as lifting and peeling under heating and humidification conditions, such as an acrylic polymer, is preferably used. Among the acrylic polymers, an acrylic copolymer having a weight average molecular weight of 10 ten thousand or more, which is obtained by blending an alkyl ester of acrylic acid having an alkyl group having 20 or less carbon atoms such as methyl, ethyl, butyl or the like with a functional group-containing acrylic monomer including (meth) acrylic acid, hydroxyethyl (meth) acrylate or the like, in such a manner that the glass transition temperature is preferably 25 ℃ or less, more preferably 0 ℃ or less, is useful as a base polymer.

The acrylic polymer is not particularly limited, and a (meth) acrylic ester base polymer such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, and a copolymer base polymer using 2 or more of these (meth) acrylates are suitably used. In addition, polar monomers may be copolymerized in these base polymers. Examples of the polar monomer include monomers having a polar functional group such as a carboxyl group, a hydroxyl group, an amide group, an amino group, and an epoxy group, such as 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, acrylamide, 2-N, N-dimethylaminoethyl (meth) acrylate, and glycidyl (meth) acrylate.

These acrylic polymers can be used alone as a binder, and a crosslinking agent is usually blended in the binder. Examples of the crosslinking agent include a crosslinking agent that is a 2-valent or polyvalent metal ion and forms a metal salt of a carboxylic acid with a carboxyl group, a crosslinking agent that is a polyamine compound and forms an amide bond with a carboxyl group, a crosslinking agent that is a polyepoxide compound, a polyol compound and forms an ester bond with a carboxyl group, a crosslinking agent that is a polyisocyanate compound and forms an amide bond with a carboxyl group, and the like. Among them, polyisocyanate compounds are widely used as organic crosslinking agents.

In the present embodiment, the method for adjusting the storage modulus of the adhesive for forming the 1 st lamination layer is not particularly limited, and examples of suitable methods include a method of blending an oligomer, specifically, a urethane acrylate oligomer, into the above-described adhesive component. Further, a substance obtained by curing an adhesive containing such urethane acrylate oligomer by irradiation with energy rays may be used. Adhesives containing urethane acrylate oligomers or adhesives with spacers obtained by applying the same to a support film (spacer) and ultraviolet curing the same are known and available from adhesive manufacturers.

In addition to the base polymer, the crosslinking agent and the oligomer, an appropriate additive such as a natural resin, a synthetic resin, a tackifying resin, an antioxidant, an ultraviolet absorber, a dye, a pigment, an antifoaming agent, a corrosion inhibitor, a photopolymerization initiator, and the like may be blended into the adhesive as needed to adjust the adhesive force, cohesion, tackiness, elastic modulus, glass transition temperature, and the like of the adhesive. Examples of the ultraviolet absorber include salicylate-based compounds, benzophenone-based compounds, benzotriazole-based compounds, cyanoacrylate-based compounds, and nickel complex-based compounds.

The thickness of the adhesive layer 21 of the 1 st adhesive layer is usually in the range of 1 to 40. Mu.m, as determined by the adhesive strength and the like. The thickness of the pressure-sensitive adhesive layer is preferably 3 to 25 μm or less, since it maintains good workability and exhibits high durability. In addition, by setting the thickness to the above range, durability against external force can be further improved.

The specific adhesive used for the 1 st adhesive layer 21 is an adhesive other than a pressure-sensitive adhesive (adhesive), and examples thereof include an aqueous adhesive and an active energy ray-curable adhesive.

Examples of the aqueous adhesive include an adhesive obtained by dissolving or dispersing a polyvinyl alcohol resin in water. The drying method when the aqueous adhesive is used is not particularly limited, and for example, a method of drying using a hot air dryer or an infrared dryer may be used.

Examples of the active energy ray-curable adhesive include solvent-free active energy ray-curable adhesives containing curable compounds that cure by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. The use of the solvent-free active energy ray-curable adhesive can improve interlayer adhesion.

The active energy ray-curable adhesive preferably contains one or both of a cationically polymerizable curable compound and a radically polymerizable curable compound, in view of exhibiting good adhesion. The active energy ray-curable adhesive may further contain a cationic polymerization initiator such as a photo-cationic polymerization initiator or a radical polymerization initiator for initiating the curing reaction of the curable compound.

Examples of the cationically polymerizable curable compound include epoxy compounds such as alicyclic epoxy compounds having an epoxy group bonded to an alicyclic ring, polyfunctional aliphatic epoxy compounds having 2 or more epoxy groups and having no aromatic ring, monofunctional epoxy compounds having 1 epoxy group (excluding the one contained in the alicyclic epoxy compounds), polyfunctional aromatic epoxy compounds having 2 or more epoxy groups and having an aromatic ring, and the like; oxetane compounds having 1 or more than 2 oxetane rings in the molecule; a combination thereof.

Examples of the radically polymerizable curable compound include (meth) acrylic compounds (compounds having 1 or 2 or more (meth) acryloyloxy groups in the molecule), other vinyl compounds having radically polymerizable double bonds, and combinations thereof.

The active energy ray-curable adhesive may contain a sensitizer such as a photosensitive aid as needed. By using the sensitizer, the reactivity is improved, and the mechanical strength and the adhesive strength of the adhesive layer can be further improved. As the sensitizer, a known sensitizer can be suitably used. When the sensitizer is blended, the blending amount is preferably in the range of 0.1 to 20 parts by mass based on 100 parts by mass of the total amount of the active energy ray-curable adhesive.

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

When an active energy ray-curable adhesive is used, an active energy ray such as ultraviolet ray, visible light, electron beam, or X-ray may be irradiated to cure a coating layer of the adhesive to form an adhesive layer. The active energy ray is preferably ultraviolet, and a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, or the like can be used as the light source in this case.

The thickness of the adhesive layer 21 of the 1 st adhesive layer is usually in the range of 0.02 to 10 μm, which is determined by the adhesive strength and the like. The thickness of the adhesive layer is preferably 1 to 4 μm from the viewpoint of further improving durability against external force.

[ Linear polarization plate ]

The linear polarization plate 10 may be any film having a polarization function of obtaining linear polarized light by transmitting light. Examples of the film include a stretched film having a dye having absorption anisotropy adsorbed thereon, and a film coated with a dye having absorption anisotropy as a polarizing plate. Examples of the dye having absorption anisotropy include dichroic dyes. Examples of the film used as a polarizing plate and coated with a dye having absorption anisotropy include a stretched film having a dye having absorption anisotropy adsorbed thereon, a film having a liquid phase layer obtained by coating a composition containing a dichroic dye having liquid crystallinity or a composition containing a dichroic dye and a polymerizable liquid crystal.

Linear polarization plate comprising stretched film as polarizing plate

A linear polarizing plate having a stretched film to which a dye having absorption anisotropy is adsorbed as a polarizing plate will be described. A stretched film having a dye having absorption anisotropy adsorbed thereon as a polarizing plate is generally produced by the following steps: the method for producing a polyvinyl alcohol resin film comprises a step of uniaxially stretching a polyvinyl alcohol resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with the dichroic dye, a step of treating the polyvinyl alcohol resin film adsorbed with the dichroic dye with an aqueous boric acid solution, and a step of washing with water after the treatment with the aqueous boric acid solution. The polarizing plate may be used as a linear polarizing plate as it is, or a member having a transparent protective film bonded to at least one surface of the polarizing plate may be used as a linear polarizing plate.

The thickness of the polarizing plate obtained by uniaxially stretching the polyvinyl alcohol resin film, dyeing with a dichroic dye, boric acid treatment, washing with water, and drying in this way is preferably 5 to 40 μm, more preferably 15 μm or less, and still more preferably 10 μm or less.

The material of the protective film to be bonded to one or both surfaces of the polarizing plate is not particularly limited, and examples thereof include a cyclic polyolefin resin film, a cellulose acetate resin film containing a resin such as triacetylcellulose or diacetylcellulose, a polyester resin film containing a resin such as polyethylene terephthalate, polyethylene naphthalate or polybutylene terephthalate, a polycarbonate resin film, a (meth) acrylic resin film, a polypropylene resin film, and the like, which are known in the art. From the viewpoint of thickness reduction, the thickness of the protective film is usually 300 μm or less, preferably 200 μm or less, more preferably 30 μm or less, and further usually 5 μm or more, and may be 10 μm or more. When the thickness of the protective film is 30 μm or less or the tensile elastic modulus at 23 ℃ is 2000MPa or more, the protective film is difficult to function as a relaxation layer for external force, and therefore, durability against external force is reduced, and defects such as peeling between phase difference layers are likely to occur. The protective film on the observation side may or may not have a retardation.

The protective film may be bonded to one or both sides of the polarizing plate via a bonding layer (hereinafter referred to as "the 2 nd bonding layer").

Linear polarization plate comprising film having liquid Crystal layer as polarizing plate

A linear polarizing plate having a film with a liquid crystal layer as a polarizing plate will be described. Examples of the film used as a polarizing plate and coated with a dye having absorption anisotropy include a film obtained by coating a composition containing a dichroic dye having liquid crystallinity, or a composition containing a dichroic dye and a liquid crystal compound. The film may be used alone as a linear polarizing plate, or may be used as a linear polarizing plate having a protective film on one or both surfaces thereof. The protective film may be the same as that of a linear polarizing plate provided with the stretched film as a polarizing plate. The protective film may be attached to one or both sides of the polarizing plate via the 2 nd attaching layer.

The thinner the film coated with the dye having absorption anisotropy is, the more preferable, but if it is too thin, the strength tends to be lowered and the workability tends to be poor. The thickness of the film is usually 20 μm or less, preferably 15 μm or less, more preferably 5 μm or less, and still more preferably 0.5 μm or more and 3 μm or less.

The film coated with the dye having absorption anisotropy is specifically a film described in japanese patent application laid-open No. 2013-33249 and the like.

As one embodiment of the linear polarizing plate, a protective film is provided on the surface of the linear polarizing plate opposite to the 1 st bonding layer.

< foremost layer >)

The linear polarization plate 10 may have an antireflection layer at the forefront. The antireflection layer has a function of preventing reflected light of external light at the surface of the linear polarization plate 10 from being observed, and can be formed by a conventional method of forming an antireflection layer or the like, that is, a coating method, a sputtering method, a vacuum deposition method, or the like. The antireflection layer may be formed on the front surface side of a protective film provided on the front surface side of the linear polarizing plate 10, and the protective film may be used to form a linear polarizing plate with an antireflection layer, or may be provided separately from the protective film.

The linear polarization plate 10 may have a surface treatment layer other than the anti-reflection layer at the forefront. Examples of such a surface treatment layer include a hard coat layer, an anti-adhesion layer, an antiglare layer, and a diffusion layer.

[ phase plate ]

The retardation plate 30 is not limited as long as it has the 1 st retardation layer 31 and the 2 nd retardation layer 32, and the 1 st retardation layer 31 and the 2 nd retardation layer 32 contain a cured product of a liquid crystal compound, and the peel strength between the 1 st retardation layer 31 and the 2 nd retardation layer 32 is 1.0N/25mm or less. The retardation plate 30 may have a 3 rd retardation layer. The 1 st phase difference layer, the 2 nd phase difference layer, and the 3 rd phase difference layer may each contain 2 or more layers.

The retardation plate 30 preferably has optical characteristics represented by the formulas (1) and (2). In order to provide the retardation plate 30 with such optical characteristics, it is sufficient that the 1 st retardation layer 31, the 2 nd retardation layer 32, or the 3 rd retardation layer has optical characteristics represented by the formulas (1) and (2), or that at least 2 selected from the 1 st retardation layer 31, the 2 nd retardation layer 32, and the 3 rd retardation layer are combined to exhibit optical characteristics represented by the formulas (1) and (2).

Re(450)/Re(550)≤1.00 (1)

1.00≤Re(650)/Re(550) (2)

In this specification, re (450) represents an in-plane phase difference value at a wavelength of 450nm, re (550) represents an in-plane phase difference value at a wavelength of 550nm, and Re (650) represents an in-plane phase difference value at a wavelength of 650 nm.

< phase difference layer >)

Examples of the retardation layer include a layer formed by polymerizing a polymerizable liquid crystal and a stretched film. The optical characteristics of the retardation layer can be adjusted by the orientation state of the polymerizable liquid crystal or the stretching method of the stretched film. The layer formed by polymerizing the polymerizable liquid crystal contains a cured product of a liquid crystal compound. In the retardation plate 30, at least the 1 st retardation layer 31 and the 2 nd retardation layer 32 are layers containing a cured product of a liquid crystal compound from the viewpoint of thickness reduction.

(layer formed by polymerizing polymerizable liquid Crystal)

In the present specification, the case where the optical axis of the polymerizable liquid crystal is oriented horizontally with respect to the substrate plane is defined as horizontal orientation, and the case where the optical axis of the polymerizable liquid crystal is oriented vertically with respect to the substrate plane is defined as vertical orientation. The optical axis is a direction in which a cross section taken in a direction orthogonal to the optical axis becomes a circle, that is, a direction in which refractive indices in all 3 directions are equal, in a refractive index ellipsoid formed by alignment of a polymerizable liquid crystal.

Examples of the polymerizable liquid crystal include a rod-shaped polymerizable liquid crystal and a disk-shaped polymerizable liquid crystal. When the rod-shaped polymerizable liquid crystal is oriented horizontally or vertically with respect to the substrate, the optical axis of the polymerizable liquid crystal coincides with the long axis direction of the polymerizable liquid crystal. When the disk-shaped polymerizable liquid crystal is aligned, the optical axis of the polymerizable liquid crystal is present in a direction perpendicular to the disk surface of the polymerizable liquid crystal.

The slow axis direction of the stretched film differs depending on the stretching method, and the slow axis and the optical axis are determined depending on the stretching method thereof such as uniaxial, biaxial, or oblique stretching.

In order to make the layer formed by polymerizing the polymerizable liquid crystal exhibit an in-plane retardation, the polymerizable liquid crystal may be aligned in an appropriate direction. When the polymerizable liquid crystal is rod-shaped, the in-plane retardation is expressed by horizontally orienting the optical axis of the polymerizable liquid crystal with respect to the substrate plane, and in this case, the optical axis direction coincides with the slow axis direction. When the polymerizable liquid crystal is discotic, the in-plane retardation is expressed by horizontally orienting the optical axis of the polymerizable liquid crystal with respect to the plane of the substrate, and in this case, the optical axis is orthogonal to the slow axis. The alignment state of the polymerizable liquid crystal can be adjusted by a combination of the alignment film and the polymerizable liquid crystal.

The in-plane retardation value of the retardation layer can be adjusted by the thickness of the retardation layer. Since the in-plane phase difference value is determined by the expression (11), Δn (λ) and the film thickness d may be adjusted to obtain a desired in-plane phase difference value (Re (λ)).

Re(λ)＝d×Δn(λ) (11)

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

The birefringence Δn (λ) is obtained by measuring the in-plane retardation value and dividing by the thickness of the retardation layer. In a specific measurement method, the characteristics of the substantial retardation layer can be measured by measuring an article obtained by forming a film on a substrate such as a glass substrate, which does not have an in-plane retardation in itself.

In this specification, refractive indexes in 3 directions in a refractive index ellipsoid formed by the orientation of a polymerizable liquid crystal or the stretching of a film are expressed as nx, ny, and nz. nx represents a principal refractive index in a direction parallel to a film plane in a refractive index ellipsoid formed by the retardation layer. ny represents the refractive index in a direction parallel to the film plane and orthogonal to the direction of nx in the refractive index ellipsoid formed by the retardation layer. nz represents the refractive index in the direction perpendicular to the film plane in the refractive index ellipsoid formed by the retardation layer.

When the optical axis of the rod-like polymerizable liquid crystal is oriented horizontally with respect to the substrate plane, the refractive index relationship of the obtained retardation layer is nx > ny≡nz (positive a plate), and the axis in the direction of nx in the refractive index ellipsoid coincides with the slow axis.

When the optical axis of the discotic polymerizable liquid crystal is oriented horizontally with respect to the plane of the substrate, the refractive index relationship of the obtained retardation layer is nx < ny≡nz (negative a plate), and the axis in the direction of ny in the refractive index ellipsoid coincides with the slow axis.

In order to cause the layer formed by polymerizing the polymerizable liquid crystal to exhibit a retardation in the thickness direction, the polymerizable liquid crystal may be aligned in an appropriate direction. In the present specification, the phase difference in the thickness direction is defined as Rth (phase difference in the thickness direction) shown in the formula (20) becomes negativeIs a characteristic of (a). Rth can be determined based on a phase difference value (R ₄₀ ) And an in-plane phase difference value (Re). That is to say,

rth can be determined by the method according to Re, R ₄₀ D (thickness of the retardation layer) and n0 (average refractive index of the retardation layer), nx, ny and nz are calculated by using the following formulas (21) to (23), and are substituted into formula (20).

Rth＝[(nx+ny)/2-nz]×d (20)

Re＝(nx-ny)×d (21)

R ₄₀ ＝(nx-ny’)×d/cos(φ) (22)

(nx+ny+nz)/3＝n0 (23)

Here the number of the elements to be processed is,

φ＝sin ^-1 〔sin(40°)/n0〕

ny’＝ny×nz/〔ny ² ×sin ² (φ)+nz ² ×cos ² (φ)〕 ^1/2

in addition, nx, ny and nz are as defined above.

When the polymerizable liquid crystal is rod-shaped, the optical axis of the polymerizable liquid crystal is oriented perpendicular to the plane of the substrate, thereby exhibiting a retardation in the thickness direction. When the polymerizable liquid crystal is disk-shaped, the optical axis of the polymerizable liquid crystal is aligned horizontally with respect to the plane of the substrate, thereby exhibiting a retardation in the thickness direction. In the case of a discotic polymerizable liquid crystal, since the optical axis of the polymerizable liquid crystal is parallel to the plane of the substrate, if Re is specified, the thickness is fixed, and thus Rth is specified unambiguously, but in the case of a rod-like polymerizable liquid crystal, since the optical axis of the polymerizable liquid crystal is perpendicular to the plane of the substrate, rth can be adjusted without changing Re by adjusting the thickness of the retardation layer.

When the optical axis of the rod-like polymerizable liquid crystal is oriented perpendicularly to the plane of the substrate, the refractive index relationship of the obtained retardation layer is nx≡ny < nz (positive C plate), and the axis in the direction of nz in the refractive index ellipsoid coincides with the slow axis direction.

When the optical axis of the discotic polymerizable liquid crystal is aligned parallel to the plane of the substrate, the refractive index relationship of the obtained retardation layer is nx < ny≡nz (negative a plate), and the axis of the direction of ny in the refractive index ellipsoid coincides with the slow axis direction.

< polymerizable liquid Crystal >)

The polymerizable liquid crystal is a compound having a polymerizable group and having liquid crystallinity. The polymerizable group means a group participating in polymerization reaction, and is preferably a photopolymerizable group. The photopolymerizable group is a group that can participate in polymerization reaction by a living radical, an acid, or the like generated by a photopolymerization initiator described later. Examples of the polymerizable group include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, oxiranyl, and oxetanyl groups. Among them, acryloyloxy, methacryloyloxy, ethyleneoxy, ethyleneoxide, and oxetanyl groups are preferable, and acryloyloxy is more preferable. The liquid crystallinity of the polymerizable liquid crystal may be either thermotropic liquid crystal or lyotropic liquid crystal, or nematic liquid crystal or smectic liquid crystal if the thermotropic liquid crystal is classified into the order.

Examples of the rod-shaped polymerizable liquid crystal include a compound represented by the following formula (a) and a compound containing a group represented by the following formula (X). The polymerizable liquid crystal having a rod shape is preferably a liquid crystal having a mesogenic structure in a T-shape or H-shape, which is oriented perpendicularly to the molecular axis direction and has birefringence, from the viewpoint of exhibiting wavelength dispersibility, and more preferably a T-shape liquid crystal from the viewpoint of obtaining stronger dispersion, and specifically, a compound represented by the following formula (a) is exemplified as the structure of the T-shape liquid crystal.

(Compound represented by the formula (A))

The formula (A) is as follows. Hereinafter, the compound represented by the formula (a) may be referred to as polymerizable liquid crystal (a).

[ chemical formula 1]

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

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

L ¹ 、L ² 、B ¹ And B ² Each independently is a single bond or a divalent linking group.

k. l each independently represents an integer of 0 to 3, and satisfies a relationship of 1.ltoreq.k+l. Here, B is, in the case of 2.ltoreq.k+l ¹ And B ² 、G ¹ And G ² Each of which may be the same or different from each other.

E ¹ And E is ² Each independently represents an alkanediyl group having 1 to 17 carbon atoms, wherein hydrogen atoms contained in the alkanediyl group may be substituted with halogen atoms, and wherein-CH contained in the alkanediyl group ₂ Can be substituted by-O-, -S-, -a substitution of the COO-group, in a system having a plurality of-O-, -S-; in the case of a-COO-group, are not adjacent to each other. P (P) ¹ And P ² Independently of one another, a polymerizable group or a hydrogen atom, at least 1 of which is a polymerizable group.

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

In addition, a plurality of G's are preferably present ¹ And G ² At least 1 of them is a divalent alicyclic hydrocarbon group, and further, more preferably with L ¹ Or L ² Bonded G ¹ And G ² At least 1 of them is a divalent alicyclic hydrocarbon group.

L ¹ And L ² Each independently is preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a1 OR ^a2 -、-R ^a3 COOR ^a4 -、-R ^a5 OCOR ^a6 -、R ^a7 OC＝OOR ^a8 -、-N＝N-、-CR ^c ＝CR ^d -, or C.ident.C-. Here, R is ^a1 ～R ^a8 Each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms, R ^c And R is ^d Represents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. L (L) ¹ And L ² More preferably each independently is a single bond, -OR ^a2-1 -、-CH ₂ -、-CH ₂ CH ₂ -、-COOR ^a4-1 -, or OCOR ^a6-1 -. Here, R is ^a2-1 、R ^a4-1 、R ^a6-1 Each independently represents a single bond, -CH ₂ -、-CH ₂ CH ₂ -any one of them. L (L) ¹ And L ² Each independently further preferably is a single bond, -O-, -CH ₂ CH ₂ -、-COO-、-COOCH ₂ CH ₂ -, or OCO-.

B ¹ And B ² Each independently is preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a9 OR ^a10 -、-R ^a11 COOR ^a12 -、-R ^a13 OCOR ^a14 -, or-R ^a15 OC(＝O)OR ^a16 -. Here, R is ^a9 ～R ^a16 Each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms. B (B) ¹ And B ² More preferably each independently is a single bond, -OR ^a10-1 -、-CH ₂ -、-CH ₂ CH ₂ -、-COOR ^a12 ^-1 -, or OCOR ^a14-1 -. Here, R is ^a10-1 、R ^a12-1 、R ^a14-1 Each independently represents a single bond, -CH ₂ -、-CH ₂ CH ₂ -any one of them. B (B) ¹ And B ² Each independently further preferably is a single bond, -O-, -CH ₂ CH ₂ -、-COO-、-COOCH ₂ CH ₂ -, -OCO-, or-OCOCH ₂ CH ₂ -。

From the viewpoint of exhibiting inverse wavelength dispersibility, k and l are preferably in the range of 2.ltoreq.k+l.ltoreq.6, preferably k+l=4, more preferably k=2 and l=2. If k=2 and l=2, a symmetrical structure is preferred.

E ¹ And E is ² The alkanediyl groups having 1 to 17 carbon atoms are preferable, and alkanediyl groups having 4 to 12 carbon atoms are more preferable.

As P ¹ Or P ² Examples of the polymerizable group include an epoxy group, a vinyl group, an ethyleneoxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an ethyleneoxy group, and an oxetanyl group. Among them, acryloyloxy, methacryloyloxy, ethyleneoxy, ethyleneoxide, and oxetanyl groups are preferable, and acryloyloxy is more preferable.

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

In the formula (A), the sum N of pi electrons contained in the 2-valent aromatic group shown by Ar _π Preferably 8 or more, more preferably 10 or more, further preferably 14 or more, and particularly preferably 16 or more. The content is preferably 30 or less, more preferably 26 or less, and even more preferably 24 or less.

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

[ chemical formula 2]

In the formulae (Ar-1) to (Ar-23), the symbol represents a linking part, Z ⁰ 、Z ¹ And Z ² Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N, N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfonyl group having 1 to 12 carbon atoms, or an N, N-dialkylsulfamoyl group having 2 to 12 carbon atoms.

Q ¹ 、Q ² And Q ³ Each independently represents-CR ^2’ R ^3’ -、-S-、-NH-、-NR ^2’ -, -CO-or O-, R ^2’ And R is ^3’ Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

J ¹ And J ² Each independently represents a carbon atom, or a nitrogen atom.

Y ¹ 、Y ² And Y ³ Each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may be substituted.

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

As Y ¹ 、Y ² And Y ³ Aromatic hydrocarbon groups in (a)Examples of the aromatic hydrocarbon group include phenyl, naphthyl, anthryl, phenanthryl, and biphenyl groups having 6 to 20 carbon atoms, and phenyl and naphthyl groups are preferred, and phenyl groups are more preferred. Examples of the aromatic heterocyclic group include an aromatic heterocyclic group having 4 to 20 carbon atoms and containing at least 1 hetero atom such as a nitrogen atom, an oxygen atom, a sulfur atom, etc., such as a furyl group, a pyrrolyl group, a thienyl group, a pyridyl group, a thiazolyl group, a benzothiazolyl group, etc., and a furyl group, a thienyl group, a pyridyl group, a thiazolyl group, a benzothiazolyl group are preferable.

Y ¹ 、Y ² And Y ³ Each independently represents an optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. Polycyclic aromatic hydrocarbon groups refer to fused polycyclic aromatic hydrocarbon groups or groups derived from an aromatic ring set. Polycyclic aromatic heterocyclic groups refer to fused polycyclic aromatic heterocyclic groups, or groups derived from an aromatic ring set.

Z ⁰ 、Z ¹ And Z ² Each independently is preferably a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, Z ⁰ More preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, and Z ¹ And Z ² Further preferred are a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group and a cyano group.

Q ¹ 、Q ² And Q ³ preferably-NH-, -S-, -NR ^2’ -、-O-，R ^2’ Preferably a hydrogen atom. Wherein, particularly preferred are-S-; -O-, -NH-.

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

In the formulae (Ar-16) to (Ar-23), Y ¹ To which nitrogen atoms and Z can be bound ⁰ Together forming an aromatic heterocyclic group. Examples of the aromatic heterocyclic group include those mentioned above as aromatic heterocyclic groups that Ar may have, such as pyrrole ring, imidazole ring, pyrroline ring, pyridine ring, pyrazine ring, pyrimidine ring, indole ring, quinoline ring, isoquinoline ring, purine ring, pyrrolidine ring, and the like. The aromatic heterocyclic group may have a substituent. In addition, Y ¹ Can be matched with itBonded nitrogen atom and Z ⁰ Together are the above-mentioned polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group which may be substituted. For example, a benzofuran ring, benzothiazole ring, benzoxazole ring, and the like can be cited.

(Compound comprising a group represented by the formula (X))

The formula (X) is as follows. Hereinafter, the compound containing the group represented by the formula (X) may be referred to as a polymerizable liquid crystal (B).

P11-B11-E11-B12-A11-B13-(X)

In the formula (X), P11 represents a polymerizable group.

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

B11 represents-O-, -S-; -CO-O- -O-CO-, -O-CO-O-, -CO-NR ¹⁶ -、-NR ¹⁶ -CO-, -CS-, or a single bond. R is R ¹⁶ Represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

B12 and B13 each independently represent-c≡c-, -ch=ch-, -CH ₂ -CH ₂ -、-O-、-S-、-C(＝O)-、-C(＝O)-O-、-O-C(＝O)-、-O-C(＝O)-O-、-CH＝N-、-N＝CH-、-N＝N-、-C(＝O)-NR ¹⁶ -、-NR ¹⁶ -C(＝O)-、-OCH ₂ -、-OCF ₂ -、-CH ₂ O-、-CF ₂ O-, -ch=ch-C (=o) -O-, -O-C (=o) -ch=ch-, or a single bond.

E11 represents an alkanediyl group having 1 to 12 carbon atoms, wherein the hydrogen atoms contained in the alkanediyl group are optionally substituted by alkoxy groups having 1 to 5 carbon atoms, and wherein the hydrogen atoms contained in the alkoxy groups are optionally substituted by halogen atoms. In addition, the-CH constituting the alkanediyl group ₂ May be substituted by-O-or-CO-.]

The number of carbon atoms of the aromatic hydrocarbon group and the alicyclic hydrocarbon group of a11 is preferably in the range of 3 to 18, more preferably in the range of 5 to 12, and particularly preferably 5 or 6. As A11, cyclohexane-1, 4-diyl, 1, 4-phenylene is preferred.

E11 is preferably a linear alkanediyl group having 1 to 12 carbon atoms. -CH constituting the alkanediyl group ₂ May be substituted by-O-.

Specifically, straight-chain alkanediyl having 1 to 12 carbon atoms such as methylene, ethylene, propane-1, 3-diyl, butane-1, 4-diyl, pentane-1, 5-diyl, hexane-1, 6-diyl, heptane-1, 7-diyl, octane-1, 8-diyl, nonane-1, 9-diyl, decane-1, 10-diyl, undecane-1, 11-diyl and dodecane-1, 12-diyl; -CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -、-CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -and-CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -and the like.

As a result of the fact that as B11, preferably-O-, -S-; -CO-O-, -O-CO-, -and of these, -CO-O-is more preferable.

As B12 and B13, each independently, is preferably-O-, -S-, -C (=o) -O-, -O-C (=o) -O-, and, of these, more preferably-O-or-O-C (=o) -O-.

The polymerizable group represented by P11 is preferably a radical polymerizable group or a cation polymerizable group in view of high polymerization reactivity, particularly photopolymerization reactivity, and is preferably a group represented by the following formulas (P-11) to (P-15) in view of easy handling and easy production of the liquid crystal compound itself.

[ chemical formula 3]

[ in the formulae (P-11) to (P-15),

R ¹⁷ ～R ²¹ each independently represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. ]

Specific examples of the group represented by the following formulas (P-11) to (P-15) include groups represented by the following formulas (P-16) to (P-20).

[ chemical formula 4]

P11 is preferably a group represented by the formulae (P-14) to (P-20), more preferably a vinyl group, a P-stilbene group, an epoxy group or an oxetanyl group.

The group represented by P11-B11-is more preferably an acryloyloxy group or a methacryloyloxy group.

Examples of the polymerizable liquid crystal (B) include compounds represented by formula (I), formula (II), formula (III), formula (IV), formula (V) and formula (VI).

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

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

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

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

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

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

(in the formula (I),

a12 to A14 each independently have the same meaning as A11, B14 to B16 each independently have the same meaning as B12, B17 has the same meaning as B11, and E12 has the same meaning as E11.

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

Specific examples of the polymerizable liquid crystal (B) include compounds having a polymerizable group among compounds described in "3.8.6 network (fully crosslinked)", "6.5.1 liquid crystal material b..polymerizable nematic liquid crystal material" of liquid crystal review (edited by the liquid crystal review and edit committee, published as 10 months and 30 days in 12 years, japanese patent application laid-open nos. 2010-31223, 2010-270108, 2011-6360 and 2011-207765.

Specific examples of the polymerizable liquid crystal (B) include compounds represented by the following formulas (I-1) to (I-4), formulas (II-1) to (II-4), formulas (III-1) to (III-26), formulas (IV-1) to (IV-26), formulas (V-1) to (V-2) and formulas (VI-1) to (VI-6). In the following formula, k1 and k2 each independently represent an integer of 2 to 12. These polymerizable liquid crystals (B) are preferable in view of ease of synthesis or ease of obtaining them.

[ chemical formula 5]

[ chemical formula 6]

[ chemical formula 7]

[ chemical formula 8]

[ chemical formula 9]

[ chemical formula 10]

[ chemical formula 11]

[ chemical formula 12]

[ chemical formula 13]

Examples of the discotic polymerizable liquid crystal include compounds containing a group represented by the formula (W) (hereinafter, may be referred to as polymerizable liquid crystal (C)).

[ chemical formula 14]

[ in formula (W), R ⁴⁰ The following formulas (W-1) to (W-5) are shown.

[ chemical formula 15]

X ⁴⁰ And Z ⁴⁰ An alkyl group having 1 to 12 carbon atoms, wherein a hydrogen atom contained in the alkyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, and a hydrogen atom contained in the alkoxy group may be substituted with a halogen atom. In addition, the-CH groups constituting the alkyl groups ₂ May be substituted by-O-or-CO-.

Specific examples of the polymerizable liquid crystal (C) include a compound described in "6.5.1 liquid crystal material b. Polymerizable nematic liquid crystal material FIG. 6.21" of liquid crystal stool (edited by liquid crystal stool editing Committee, issued by Wan Kagaku Co., ltd., hei.e., 12 years, 10 months, 30 days), a polymerizable liquid crystal described in JP-A-7-258170, JP-A-7-30637, JP-A-7-309807, and JP-A-8-231470.

The retardation plate 30 having the optical characteristics represented by the formulas (1) and (2) can be obtained by combining the layers having the optical characteristics represented by the formulas (4), (6) and (7) with the layers having the optical characteristics represented by the formulas (5), (6) and (7) in a specific slow axis relationship when polymerizing the polymerizable liquid crystal having a specific structure, stretching the polymer film having a specific structure, or the like.

Re(450)/Re(550)≤1.00 (1)

1.00≤Re(650)/Re(550) (2)

100nm＜Re(550)＜160nm (4)

200nm＜Re(550)＜320nm (5)

Re(450)/Re(550)≥1.00 (6)

1.00≥Re(650)/Re(550) (7)

The retardation plate 30 preferably has optical characteristics represented by the formulas (1) and (2). If the retardation plate 30 has the optical characteristics shown in the formulas (1) and (2), the same polarization conversion characteristic can be obtained for each wavelength of light in the visible light region, and light leakage at the time of black display of a display device such as an organic EL display device can be suppressed.

Examples of the polymerizable liquid crystal having a specific structure include the polymerizable liquid crystal (a). The retardation layer having the optical characteristics represented by the formulas (1) and (2) can be obtained by aligning the polymerizable liquid crystal (a) so as to be horizontal to the substrate plane optical axis, and the retardation layer having the desired in-plane retardation value such as the optical characteristics represented by the formula (4) can be obtained by adjusting the film thickness according to the formula (10).

100nm＜Re(550)＜160nm (4)

As a method of combining the layers having the optical characteristics represented by the formulas (4), (6) and (7) and the layers having the optical characteristics represented by the formulas (5), (6) and (7) in a specific slow axis relationship, a known method is exemplified.

For example, japanese patent application laid-open No. 2001-4837, japanese patent application laid-open No. 2001-21710 and Japanese patent application laid-open No. 2000-206331 disclose retardation films having at least 2 retardation layers formed of liquid crystal compounds.

The retardation layer having the optical characteristics represented by the above formula (6) and formula (7) can be obtained by a known method. That is, the retardation layer obtained by a method other than the method for obtaining the retardation layer having the optical characteristics shown in the above-mentioned formula (1) and formula (2) has the optical characteristics shown in the general formulas (6) and (7).

(1 st phase-difference layer)

The 1 st retardation layer 31 preferably has optical characteristics represented by the formula (4) (in this specification, a retardation layer satisfying the optical characteristics represented by the formula (4) is also referred to as "λ/4 layer"), and more preferably has optical characteristics represented by the formula (4-1). The in-plane phase difference value Re (550) can be adjusted by the same method as the method for adjusting the in-plane phase difference value of the above-described phase difference layer.

100nm＜Re(550)＜160nm (4)

130nm＜Re(550)＜150nm (4-1)

The 1 st retardation layer preferably has optical characteristics represented by the formulas (1) and (2) (in this specification, the optical characteristics represented by the formulas (1) and (2) are also referred to as "inverse dispersibility"). The optical characteristics can be obtained by the same method as the retardation layer.

Re(450)/Re(550)≤1.00 (1)

1.00≤Re(650)/Re(550) (2)

The 1 st retardation layer preferably includes: a layer a having optical characteristics represented by formulae (4), (6) and (7), and a layer B having optical characteristics represented by formulae (5), (6) and (7). The optical characteristics can be obtained by the same method as the above-described retardation layer.

100nm＜Re(550)＜160nm (4)

200nm＜Re(550)＜320nm (5)

Re(450)/Re(550)≥1.00 (6)

1.00≥Re(650)/Re(550) (7)

Layer A is preferably a layer having optical characteristics represented by formula (4-1), and layer B is preferably a layer having optical characteristics represented by formula (5-1).

130nm＜Re(550)＜150nm (4-1)

265nm＜Re(550)＜285nm (5-1)

In the case where the retardation plate has the 3 rd retardation layer, the 1 st retardation layer preferably has optical characteristics represented by the formulae (6) and (7). The optical characteristics can be obtained by the same method as the above-described retardation layer.

Re(450)/Re(550)≥1.00 (6)

1.00≥Re(650)/Re(550) (7)

The 1 st retardation layer is a coating layer formed by polymerizing 1 or more kinds of polymerizable liquid crystals. When the 1 st retardation layer includes 1 retardation layer and has the optical characteristics represented by the formulas (1) and (2), the retardation layer is preferably a coating layer formed by polymerizing the polymerizable liquid crystal (a). When the 2 nd retardation layer has the optical characteristics represented by the formulas (6) and (7), the retardation layer is preferably a coating layer formed by polymerizing the polymerizable liquid crystal (B).

The layer a is preferably a coating layer formed by polymerizing the polymerizable liquid crystal (B). The layer B is preferably a coating layer formed by polymerizing the polymerizable liquid crystal (C).

The 1 st retardation layer is a layer formed by polymerizing a polymerizable liquid crystal, and its thickness is usually 20 μm or less, preferably 5 μm or less, more preferably 0.5 μm or more and 3 μm or less. The thickness of the 1 st retardation layer can be obtained by measurement with an interferometer, a laser microscope, or a stylus film thickness meter.

(No. 2 phase-difference layer)

The 2 nd retardation layer 32 preferably has optical characteristics (positive C plate) represented by formula (3).

nx≈ny＜nz (3)

The in-plane retardation Re (550) of the 2 nd retardation layer is usually in the range of 0 to 10nm, preferably in the range of 0 to 5 nm. The phase difference Rth (550) in the thickness direction is usually in the range of-10 to-300 nm, preferably-20 to-200 nm. The in-plane phase difference value Re (550) and the thickness-direction phase difference value Rth (550) can be adjusted by the same method as the above-described phase difference layer.

The 2 nd retardation layer is a coating layer formed by polymerizing 1 or more kinds of polymerizable liquid crystals. More preferably, the coating layer is formed by polymerizing the polymerizable liquid crystal (B).

The 2 nd retardation layer is a layer formed by polymerizing a polymerizable liquid crystal, and its thickness is usually 10 μm or less, preferably 5 μm or less, more preferably 0.3 μm or more and 3 μm or less. The thickness of the 2 nd retardation layer can be obtained by the same method as that of the 1 st retardation layer. The thicknesses of the 1 st phase difference layer and the 2 nd phase difference layer are preferably 5 μm or less, respectively.

(3 rd phase-difference layer)

The 3 rd retardation layer preferably has optical characteristics represented by the formula (5), and more preferably has optical characteristics represented by the formula (5-1). The in-plane phase difference value Re (550) can be adjusted by the same method as the method for adjusting the in-plane phase difference value of the above-described phase difference layer.

200nm＜Re(550)＜320nm (5)

265nm＜Re(550)＜285nm (5-1)

The 3 rd retardation layer preferably has optical characteristics represented by the formulae (6) and (7). The optical characteristics can be obtained by the same method as the retardation layer.

Re(450)/Re(550)≥1.00 (6)

1.00≥Re(650)/Re(550) (7)

The 3 rd retardation layer is preferably a coating layer formed by polymerizing 1 or more kinds of polymerizable liquid crystals. More preferably, the coating layer is formed by polymerizing the polymerizable liquid crystal (B) or (C).

The 3 rd retardation layer may be a stretched film, and in the case of a stretched film, the thickness thereof is usually 300 μm or less, preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less. When the 3 rd retardation layer is a layer formed by polymerizing a polymerizable liquid crystal, the thickness thereof is usually 10 μm or less, preferably 5 μm or less, more preferably 0.5 μm or more and 5 μm or less. The thickness of the 3 rd retardation layer can be obtained by the same method as that of the 1 st retardation layer.

(substrate)

The phase difference plate 30 may have a base material. The substrate is typically a transparent substrate. The transparent substrate is a substrate having transparency capable of transmitting light, particularly visible light, and the transparency is a characteristic that the transmittance for light rays having a wavelength in the range of 380 to 780nm is 80% or more. Specific examples of the transparent substrate include a light-transmitting resin substrate. Examples of the resin constituting the light-transmitting resin base material include polyolefin such as polyethylene and polypropylene; cyclic olefin resins such as norbornene polymers; polyvinyl alcohol; polyethylene terephthalate; a polymethacrylate; a polyacrylate; cellulose esters such as triacetylcellulose, diacetylcellulose, and cellulose acetate propionate; polyethylene naphthalate; a polycarbonate; polysulfone; polyether sulfone; polyether ketone; polyphenylene sulfide and polyphenylene oxide. From the viewpoints of ease of obtaining and transparency, polyethylene terephthalate, polymethacrylate, cellulose ester, cycloolefin resin, or polycarbonate is preferable.

The surface of the substrate on the side where the alignment film, the 1 st retardation layer, the 2 nd retardation layer, and the 3 rd retardation layer are formed may be subjected to surface treatment before forming the alignment film or the retardation layer. Examples of the surface treatment method include a method of treating the surface of a substrate with corona or plasma under vacuum or atmospheric pressure, a method of treating the surface of a substrate with laser light, a method of treating the surface of a substrate with ozone, a method of saponifying the surface of a substrate or a method of flame treating the surface of a substrate, a method of primer-treating the surface of a substrate with a coupling agent, a graft polymerization method of causing a reactive monomer or a reactive polymer to adhere to the surface of a substrate and then irradiating the substrate with radiation, plasma or ultraviolet light to react the same, and the like. Among them, a method of subjecting the surface of the substrate to corona or plasma treatment under vacuum or atmospheric pressure is preferable.

As a method for treating the surface of the substrate by corona or plasma, there is a method in which the substrate is placed between opposing electrodes under a pressure in the vicinity of atmospheric pressure, and the surface of the substrate is treated by generating corona or plasma; a method of flowing a gas between the opposing electrodes, plasmatizing the gas between the electrodes, and blowing the plasmatized gas onto the substrate; and a method of generating glow discharge plasma under low pressure conditions to perform surface treatment of a substrate.

Among them, a method of disposing a substrate between opposing electrodes under a pressure in the vicinity of atmospheric pressure, and generating corona or plasma to perform surface treatment of the substrate is preferable; or a method in which a gas is flowed between the electrodes facing each other, the gas is converted into plasma between the electrodes, and the converted gas is blown onto the substrate. The surface treatment with corona or plasma is generally performed by a commercially available surface treatment apparatus.

The substrate is preferably a substrate having a small phase difference. Examples of the base material having a small retardation include cellulose ester films having no retardation, such as ZeroTAC (registered trademark) (Konica Minolta Opto corporation) and Z-TAC (fuji film corporation). In addition, an unstretched cycloolefin resin base material is also preferable.

The surface of the substrate on which the alignment film, the 1 st retardation layer, the 2 nd retardation layer, and the 3 rd retardation layer are not formed may be subjected to a hard coat treatment, an antistatic treatment, or the like. Further, an additive such as an ultraviolet absorber may be contained within a range not affecting the performance.

If the thickness of the base material is too small, the strength tends to be low and the workability tends to be poor, and therefore, the thickness is usually 5 to 300. Mu.m, preferably 10 to 200. Mu.m.

(polymerizable liquid Crystal composition)

The layer (retardation layer) formed by polymerizing the polymerizable liquid crystal is generally formed by applying a composition containing 1 or more kinds of polymerizable liquid crystal (hereinafter, may be referred to as a polymerizable liquid crystal composition) to a substrate, an alignment film, a protective layer, or a retardation layer, and polymerizing the polymerizable liquid crystal in the obtained coating film.

The polymerizable liquid crystal composition generally contains a solvent, and as the solvent, a solvent which can dissolve the polymerizable liquid crystal and is inactive to the polymerization reaction of the polymerizable liquid crystal is more preferable.

Specific examples of the solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, and phenol; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, cycloheptanone, methyl amyl ketone, methyl isobutyl ketone, and N-methyl-2-pyrrolidone; non-chlorinated aliphatic hydrocarbon solvents such as pentane, hexane, heptane, etc.; non-chlorinated aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as propylene glycol monomethyl ether, tetrahydrofuran, and dimethoxyethane; chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These other solvents may be used alone or in combination.

The content of the solvent in the polymerizable liquid crystal composition is usually preferably 10 to 10000 parts by mass, more preferably 50 to 5000 parts by mass, per 100 parts by mass of the solid content. The solid component refers to the total of components after the solvent is removed from the polymerizable liquid crystal composition.

The polymerizable liquid crystal composition is usually applied by a known method such as spin coating, liquid extrusion, gravure coating, die coating, slit coating, bar coating, applicator, or printing, such as flexography. After the coating, the solvent is usually removed under the condition that the polymerizable liquid crystal contained in the obtained coating film is not polymerized, thereby forming a dry coating film. Examples of the drying method include a natural drying method, a ventilation drying method, a heat drying method, and a reduced pressure drying method.

(alignment film)

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

The alignment film is preferably one having solvent resistance which is insoluble by coating or the like of the polymerizable liquid crystal composition and heat resistance in a heat treatment for removing a solvent and aligning the polymerizable liquid crystal. Examples of the alignment film include an alignment film comprising an alignment polymer, a photo-alignment film, and a groove alignment film having a surface with a concave-convex pattern and a plurality of grooves formed thereon to align the grooves.

Examples of the alignment polymer include polyamide having an amide bond in the molecule, gelatin, polyimide having an imide bond in the molecule, and polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethylenimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylate which are hydrolysates thereof. Among them, polyvinyl alcohol is preferable. More than 2 kinds of oriented polymers may be used in combination.

An oriented film comprising an oriented polymer can generally be obtained by: a composition obtained by dissolving an oriented polymer in a solvent (hereinafter, sometimes referred to as an oriented polymer composition) is applied to a substrate and the solvent is removed, or an oriented polymer composition is applied to a substrate and the solvent is removed, and rubbing (rubbing method) is performed.

Examples of the solvent include alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether, ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ -butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate, ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, and methyl isobutyl ketone, aliphatic hydrocarbon solvents such as pentane, hexane, and heptane, aromatic hydrocarbon solvents such as toluene, and xylene, nitrile solvents such as acetonitrile, ether solvents such as tetrahydrofuran, and dimethoxyethane, and chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These solvents may be used alone or in combination of two or more.

The concentration of the alignment polymer in the alignment polymer composition may be within a range in which the alignment polymer material is completely soluble in the solvent, and is preferably about 0.1% to 20%, more preferably about 0.1% to 10% in terms of solid content, relative to the solution.

As the alignment polymer composition, a commercially available alignment film material can be used as it is. Examples of commercially available alignment film materials include SUNEVER (registered trademark, manufactured by Nissan chemical Co., ltd.), optomer (registered trademark, manufactured by JSR Co., ltd.), and the like.

Examples of the method of applying the alignment polymer composition to the substrate include known methods such as spin coating, liquid extrusion, gravure coating, die coating, slit coating, bar coating, applicator, and printing such as flexography. When the retardation layer is produced by a Roll-to-Roll (Roll to Roll) continuous production method described later, a printing method such as a gravure coating method, a die coating method, or a flexographic method is generally used as the coating method.

Examples of the method for removing the solvent contained in the oriented polymer composition include a natural drying method, a pneumatic drying method, a heat drying method, and a vacuum drying method.

In order to impart an orientation regulating force to the orientation film, rubbing (rubbing method) may be performed as necessary.

As a method of imparting an orientation regulating force by a rubbing method, there is a method of bringing a rubbing roller around which a rubbing cloth is wound and rotated into contact with a film of an orientation polymer formed on the surface of a substrate by applying an orientation polymer composition onto the substrate and annealing the composition.

In order to impart an alignment regulating force to the alignment film, photo alignment (photo alignment method) may be performed as needed.

The photo-alignment film is generally obtained by applying a composition containing a polymer having a photoreactive group or a monomer and a solvent (hereinafter, sometimes referred to as a "composition for forming a photo-alignment film") to a substrate and irradiating light (preferably polarized light UV). The photo-alignment film is more preferable in that the direction of the alignment restricting force can be arbitrarily controlled by selecting the polarization direction of the irradiated light.

The photoreactive group refers to a group that generates liquid crystal aligning ability by irradiation with light. Specifically, a group involved in a photoreaction that causes the liquid crystal aligning ability, such as an alignment induction or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photodecomposition reaction of a molecule generated by light irradiation, is exemplified. Among them, a group participating in dimerization reaction or photocrosslinking reaction is preferable in view of excellent orientation. As the photoreactive group, a group having an unsaturated bond, particularly a double bond, is preferable, and a group having at least one selected from a carbon-carbon double bond (c=c bond), a carbon-nitrogen double bond (c=n bond), a nitrogen-nitrogen double bond (n=n bond), and a carbon-oxygen double bond (c=o bond) is particularly preferable.

Examples of the photoreactive group having a c=c bond include a vinyl group, a polyalkenyl group, a stilbene oxazolyl group, a stilbene oxazolium group, a chalcone group, and a cinnamoyl group. Examples of the photoreactive group having a c=n bond include a group having a structure such as an aromatic Schiff base or an aromatic hydrazone. Examples of the photoreactive group having an n=n bond include an azo phenyl group, an azo naphthyl group, an aromatic heterocyclic azo group, a disazo group, a formazan group, and a group having an azobenzene oxide structure. Examples of the photoreactive group having a c=o bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, haloalkyl, and the like.

Among them, the photoreactive group involved in the photodimerization reaction is preferable, and cinnamoyl and chalcone groups are preferable in terms of the light irradiation amount of the polarized light required for the photoalignment is small, and the photoalignment film excellent in thermal stability and temporal stability is easily obtained. As the polymer having a photoreactive group, a polymer having a cinnamoyl group in which the terminal portion of the side chain of the polymer has a cinnamic acid structure is particularly preferable.

By applying the composition for forming a photo-alignment film to a substrate, a photo-alignment inducing layer can be formed on the substrate. The solvent contained in the composition may be the same as the solvent phase contained in the above-mentioned oriented polymer composition, and may be appropriately selected according to the solubility of the polymer or monomer having a photoreactive group.

The content of the polymer or monomer having a photoreactive group in the composition for forming a photoalignment film may be appropriately adjusted according to the kind of the polymer or monomer and the thickness of the target photoalignment film, and is preferably at least 0.2 mass%, more preferably in the range of 0.3 to 10 mass%. The composition for forming a photo-alignment film may further contain a polymer material such as polyvinyl alcohol or polyimide, and a photosensitizer, within a range where the properties of the photo-alignment film are not significantly impaired.

As a method of applying the composition for forming a photo-alignment film to a substrate, the same method as the method of applying the composition for forming an alignment polymer to a substrate can be mentioned. As a method for removing the solvent from the composition for forming a coated photo-alignment film, for example, the same method as that for removing the solvent from the alignment polymer composition can be mentioned.

The irradiation of polarized light may be performed by directly irradiating the substrate with polarized light UV from a substance obtained by removing the solvent from the composition for forming a photo-alignment film applied to the substrate, or by irradiating the substrate with polarized light and transmitting the polarized light. In addition, the polarized light is particularly preferably substantially parallel light. Regarding the wavelength of the irradiated polarized light, the wavelength in the wavelength region in which the photoreactive group of the polymer or monomer having the photoreactive group can absorb light energy is preferable. Specifically, UV (ultraviolet) in the wavelength range of 250 to 400nm is particularly preferable. Examples of the light source used for the polarized light irradiation include a xenon lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, an ultraviolet laser such as KrF or ArF, and more preferably a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp. These lamps are preferable because of their high emission intensity of ultraviolet rays having a wavelength of 313 nm. The polarized light UV can be irradiated by irradiating the light from the light source through an appropriate polarizer. As the polarizing plate, a polarizing prism such as a polarizing filter, a glato thompson, a glato taylor, or a wire grid type polarizing plate can be used.

In rubbing or polarized light irradiation, if masking is performed, a plurality of regions (patterns) having different directions of alignment of the liquid crystal may be formed.

The groove alignment film is a film in which liquid crystal alignment is obtained by a concave-convex pattern or a plurality of grooves on the film surface. According to H.V.KENNEL et al, there is reported the fact that when liquid crystal molecules are placed on a substrate having a plurality of linear grooves (grooves) arranged at equal intervals, the liquid crystal molecules are aligned in the direction along the grooves (Physical Review A (5), page 2713, 1981).

Specific examples of the method for obtaining the groove alignment film include a method in which a photosensitive polyimide film is exposed to light through an exposure mask having a slit with a periodic pattern shape, and then developed and rinsed to remove an unnecessary polyimide film, thereby forming a concave-convex pattern; a method in which a UV curable resin layer is formed on a plate-shaped master having grooves on the surface, and the resin layer is transferred to a base film and then cured; as a method of conveying a base film on which a UV curable resin layer is formed, pressing a master having a roll shape with a plurality of grooves on the surface of the UV curable resin layer to form irregularities, and then curing, a method described in japanese patent application laid-open No. 6-34976 and japanese patent application laid-open No. 2011-242743, or the like can be used.

Among the above methods, a method is preferable in which a master having a roll shape with a plurality of grooves is pressed against the surface of a UV curable resin layer to form irregularities, and then cured. As the roll master, stainless (SUS) steel may be used from the viewpoint of durability.

As the UV curable resin, a polymer of monofunctional acrylate, a polymer of polyfunctional acrylate, or a polymer of a mixture thereof may be used.

The monofunctional acrylate has 1 group selected from acryloyloxy groups (CH) ₂ =ch-COO-) and methacryloxy (CH ₂ ＝C(CH ₃ ) The group in-COO- (hereinafter, may be referred to as a (meth) acryloyloxy group). ) Is a compound of (a).

Examples of the monofunctional acrylate having 1 (meth) acryloyloxy group include alkyl (meth) acrylate having 4 to 16 carbon atoms, β -carboxyalkyl (meth) acrylate having 2 to 14 carbon atoms, alkylated phenyl (meth) acrylate having 2 to 14 carbon atoms, methoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, isobornyl (meth) acrylate, and the like.

Multifunctional acrylates are generally compounds having 2 to 6 (meth) acryloyloxy groups in the molecule.

As the 2-functional acrylate having 2 (meth) acryloyloxy groups, 1, 3-butanediol di (meth) acrylate can be exemplified; 1, 3-butanediol (meth) acrylate; 1, 6-hexanediol di (meth) acrylate; ethylene glycol di (meth) acrylate; diethylene glycol di (meth) acrylate; neopentyl glycol di (meth) acrylate; triethylene glycol di (meth) acrylate; tetraethylene glycol di (meth) acrylate; polyethylene glycol diacrylate; bis (acryloyloxyethyl) ether of bisphenol a; ethoxylated bisphenol-a di (meth) acrylate; propoxylated neopentyl glycol di (meth) acrylate; ethoxylated neopentyl glycol di (meth) acrylate and 3-methylpentanediol di (meth) acrylate, and the like.

As the polyfunctional acrylate having 3 to 6 (meth) acryloyloxy groups, trimethylolpropane tri (meth) acrylate is exemplified; pentaerythritol tri (meth) acrylate; tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate; ethoxylated trimethylolpropane tri (meth) acrylate; propoxylated trimethylolpropane tri (meth) acrylate; pentaerythritol tetra (meth) acrylate; dipentaerythritol penta (meth) acrylate; dipentaerythritol hexa (meth) acrylate; tripentaerythritol tetra (meth) acrylate; tripentaerythritol penta (meth) acrylate; tripentaerythritol hexa (meth) acrylate; tripentaerythritol hepta (meth) acrylate; tripentaerythritol octa (meth) acrylate; reaction products of pentaerythritol tri (meth) acrylate with anhydride; reaction products of dipentaerythritol penta (meth) acrylate with anhydride; reaction products of tripentaerythritol hepta (meth) acrylate with anhydrides; caprolactone-modified trimethylolpropane tri (meth) acrylate; caprolactone-modified pentaerythritol tri (meth) acrylate; caprolactone-modified tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate; caprolactone-modified pentaerythritol tetra (meth) acrylate; caprolactone-modified dipentaerythritol penta (meth) acrylate; caprolactone-modified dipentaerythritol hexa (meth) acrylate; caprolactone-modified tripentaerythritol tetra (meth) acrylate; caprolactone-modified tripentaerythritol penta (meth) acrylate; caprolactone-modified tripentaerythritol hexa (meth) acrylate; caprolactone-modified tripentaerythritol hepta (meth) acrylate; caprolactone-modified tripentaerythritol octa (meth) acrylate; reaction products of caprolactone-modified pentaerythritol tri (meth) acrylate with anhydride; reaction products of caprolactone-modified dipentaerythritol penta (meth) acrylate and acid anhydride, caprolactone-modified tripentaerythritol hepta (meth) acrylate and acid anhydride, and the like. In the specific examples of the multifunctional acrylate shown here, (meth) acrylate means acrylate or methacrylate. Further, caprolactone modification refers to an open ring or ring-opened polymer in which caprolactone is introduced between an alcohol-derived site of a (meth) acrylate compound and a (meth) acryloyloxy group.

The multifunctional acrylate may be commercially available. Examples of such commercial products include A-DOD-N, A-HD-N, A-NOD-N, APG-100, APG-200, APG-400, A-GLY-9E, A-GLY-20E, A-TMM-3, A-TMPT, AD-TMP, ATM-35E, A-TMMT, A-9550, A-DPH, HD-N, NOD-N, NPG, TMPT (manufactured by New Zhongcun chemical Co., ltd.), "ARONIXM-220", ARONIX "M-325", ARONIX "M-240", ARONIX "M-270", ARONIX "M-309" ARONIX "M-310", ARONIX "M-321", ARONIX "M-350", ARONIX "M-360", ARONIX "M-305", ARONIX "M-450", ARONIX "M-451", ARRY "M-N, NPG, TMPT" (manufactured by Tokyo corporation, "ARONECL" 40-ECL "ARECL" CO "40", ARECL "ECL" 37-406 ", and the like" ARONECL "ECL" 40", and the like).

The width of the convex portion is preferably 0.05 to 5 μm, the width of the concave portion is preferably 0.1 to 5 μm, and the depth of the height difference of the concave and convex portion is 2 μm or less, preferably 0.01 to 1 μm or less. If the ratio is within this range, liquid crystal alignment with less alignment disorder can be obtained.

The thickness of the alignment film is usually in the range of 10nm to 10000nm, preferably in the range of 10nm to 1000nm, more preferably 500nm or less, and still more preferably in the range of 10nm to 500 nm.

The liquid crystal alignment of the polymerizable liquid crystal is controlled by the properties of the alignment film and the polymerizable liquid crystal. For example, if the alignment film is a material exhibiting a horizontal alignment regulating force as an alignment regulating force, the polymerizable liquid crystal may be horizontally aligned or hybrid aligned, and if the alignment film is a material exhibiting a vertical alignment regulating force, the polymerizable liquid crystal may be vertically aligned or tilted aligned. The orientation regulating force can be arbitrarily adjusted according to the surface state and rubbing condition in the case where the orientation film is formed of an oriented polymer, and can be arbitrarily adjusted according to the polarized light irradiation condition in the case where the orientation film is formed of a photo-oriented polymer. In addition, the liquid crystal orientation can be controlled by selecting physical properties such as surface tension and liquid crystallinity of the polymerizable liquid crystal.

The polymerization of the polymerizable liquid crystal can be performed by a known method of polymerizing a compound having a polymerizable functional group. Specifically, thermal polymerization and photopolymerization are exemplified, and photopolymerization is preferable from the viewpoint of easiness of polymerization. When polymerizing a polymerizable liquid crystal by photopolymerization, it is preferable to apply a polymerizable liquid crystal composition containing a photopolymerization initiator, prepare a liquid crystal phase state of the polymerizable liquid crystal in a dried film obtained by drying, and then perform photopolymerization while maintaining the liquid crystal phase state.

Photopolymerization is usually carried out by irradiating a dry film with light. The light to be irradiated is appropriately selected depending on the type of photopolymerization initiator contained in the dried film, the type of polymerizable liquid crystal (particularly, the type of photopolymerization group contained in the polymerizable liquid crystal), and the amount thereof, and specifically, light selected from visible light, ultraviolet light, and laser light, and an active electron beam are exemplified. Among them, ultraviolet light is preferable from the viewpoint of easy control of the progress of polymerization reaction and the viewpoint of using a device widely used in the art as a photopolymerization device, and the types of polymerizable liquid crystal and photopolymerization initiator are preferably selected so that photopolymerization can be performed by ultraviolet light. In addition, in the polymerization, the polymerization temperature can be controlled by irradiating the dried film with light while cooling the film by an appropriate cooling method. If the polymerization of the polymerizable liquid crystal is carried out at a lower temperature by using such a cooling method, the retardation layer can be formed appropriately even if a substrate having relatively low heat resistance is used. In photopolymerization, a patterned retardation layer can also be obtained by masking, developing, or the like.

The polymerizable liquid crystal composition may contain a reactive additive. As the reactive additive, a reactive additive having a carbon-carbon unsaturated bond and an active hydrogen reactive group in its molecule is preferable. The term "active hydrogen-reactive group" as used herein means a group selected from the group consisting of carboxyl group (-COOH), hydroxyl group (-OH), and amino group (-NH) ₂ ) Typical examples of the reactive group include a group having active hydrogen such as a glycidyl group, an oxazoline group, a carbodiimide group, an aziridine group, an imide group, an isocyanate group, an isothiocyanate group, and a maleic anhydride group. The number of the carbon-carbon unsaturated bond and the active hydrogen reactive group contained in the reactive additive is usually 1 to 20, preferably 1 to 10, respectively.

In the reactive additive, at least 2 active hydrogen reactive groups are preferably present, in which case the presence of a plurality of active hydrogen reactive groups may be the same or different.

The reactive additive may have carbon-carbon unsaturation that is a carbon-carbon double bond or a carbon-carbon triple bond, or a combination thereof, preferably a carbon-carbon double bond. Among them, as the reactive additive, carbon-carbon unsaturated bonds are preferably contained in the form of vinyl groups and/or (meth) acryl groups. Furthermore, the active hydrogen reactive group is preferably at least 1 selected from the group consisting of an epoxy group, a glycidyl group and an isocyanate group, and particularly preferably a reactive additive having an acryl group and an isocyanate group.

Specific examples of the reactive additive include compounds having a (meth) acryloyl group and an epoxy group, such as methacryloxyglycidyl ether and acryloxyglycidyl ether; compounds having a (meth) acryloyl group and an oxetanyl group, such as oxetane acrylate and oxetane methacrylate; compounds having a (meth) acryloyl group and a lactone group, such as lactone acrylate and lactone methacrylate; compounds having vinyl groups and oxazolinyl groups such as vinyl oxazoline and isopropenyl oxazoline; and oligomers of compounds having a (meth) acryloyl group and an isocyanate group such as isocyanatomethyl acrylate, isocyanatomethyl methacrylate, 2-isocyanatoethyl acrylate and 20-isocyanatoethyl methacrylate. Examples of the compound include compounds having a vinyl group, vinylidene group, and acid anhydride, such as methacrylic anhydride, acrylic anhydride, maleic anhydride, and vinyl maleic anhydride. Among them, methacryloxyglycidyl ether, acryloxyglycidyl ether, isocyanatomethyl acrylate, isocyanatomethyl methacrylate, vinyl oxazoline, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate and the above-mentioned oligomer are preferable, and isocyanatomethyl acrylate, 2-isocyanatoethyl acrylate and the above-mentioned oligomer are particularly preferable.

Specifically, a compound represented by the following formula (Y) is preferable.

[ chemical formula 16]

In the formula (Y) of the present invention,

n represents an integer of 1 to 10, R ^1’ Represents a 2-valent aliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms or a 2-valent aromatic hydrocarbon group having 5 to 20 carbon atoms. 2R in each repeating unit ^2’ One of them is-NH-, the other is > N-C (=O) -R ^3’ The radicals shown. R is R ^3’ Represents a group having a hydroxyl group or a carbon-carbon unsaturated bond.

R in formula (Y) ^3’ In at least 1R ^3’ Is a group having a carbon-carbon unsaturated bond.]

Among the reactive additives represented by the above formula (Y), a compound represented by the following formula (YY) (hereinafter, sometimes referred to as a compound (YY)) is particularly preferable (n is the same as the above).

[ chemical formula 17]

The compound (YY) may be used as it is or after purification as required. As a commercially available product, laromer (registered trademark) LR-9000 (manufactured by BASF corporation) is exemplified.

When the polymerizable liquid crystal composition contains a reactive additive, the content thereof is usually 0.1 to 30 parts by mass, preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal.

The polymerizable liquid crystal composition preferably contains 1 or more leveling agents. The leveling agent has a function of adjusting fluidity of the polymerizable liquid crystal composition and flattening a coating film obtained by coating the polymerizable liquid crystal composition, and specifically, a surfactant is exemplified. As the leveling agent, at least 1 kind selected from the group consisting of a leveling agent having a polyacrylate compound as a main component and a leveling agent having a fluorine atom-containing compound as a main component is preferable.

As leveling agents containing polyacrylate compounds as a main component, "BYK-350", "BYK-352", "BYK-353", "BYK-354", "BYK-355", "BYK-358N", "BYK-361N", "BYK-380", "BYK-381" and "BYK-392" [ BYK Chemie Co. ].

As leveling agents containing fluorine atom-containing compounds as the main component, "Megafac (registered trademark) R-08", megafac "R-30", megafac "R-90", megafac "F-410", megafac "F-411", megafac "F-443", megafac "F-445", megafac "F-470", megafac "F-471", megafac "F-477", megafac "F-479", megafac "F-482" and Megafac "F-483" [ DIC Co., ltd.); "Surflon (registered trademark) S-381", surflon "S-382", surflon "S-383", surflon "S-393", surflon "SC-101", surflon "SC-105", "KH-40" and "SA-100" [ AGC SEIMICHEMICAL, inc ]; "E1830", "E5844" [ Daikin Fine Chemical Laboratories, inc.; "EFTOP EF301", "EFTOP EF303", "EFTOP EF351" and "EFTOP EF352" [ Mitsubishi Materials Electronic Chemicals, inc. ].

When the polymerizable liquid crystal composition contains a leveling agent, the content thereof is preferably 0.01 parts by mass or more and 5 parts by mass or less, more preferably 0.05 parts by mass or more and 5 parts by mass or less, and still more preferably 0.05 parts by mass or more and 3 parts by mass or less, relative to 100 parts by mass of the polymerizable liquid crystal. If the content of the leveling agent is within the above range, there is a tendency that the polymerizable liquid crystal is easily oriented horizontally and the resulting polarizing layer becomes smoother. If the content of the leveling agent relative to the polymerizable liquid crystal is within the above range, the obtained retardation layer tends to be less likely to be uneven.

The polymerizable liquid crystal composition preferably contains 1 or more polymerization initiators. The polymerization initiator is a compound capable of initiating polymerization of the polymerizable liquid crystal, and is preferably a photopolymerization initiator in view of initiating polymerization under a lower temperature condition. Specifically, a photopolymerization initiator capable of generating a living radical or an acid by the action of light is exemplified, and among them, a photopolymerization initiator capable of generating a radical by the action of light is preferable.

Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkyl phenone compounds, acyl phosphine oxide compounds, triazine compounds, iodonium salts and sulfonium salts.

Examples of the benzoin compound include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

Examples of the benzophenone compound include benzophenone, methyl o-benzoyl benzoate, 4-phenyl benzophenone, 4-benzoyl-4 ' -methyl diphenyl sulfide, 3', 4' -tetra (t-butylperoxycarbonyl) benzophenone, and 2,4, 6-trimethylbenzophenone.

Examples of the alkylbenzene ketone compound include oligomers of diethoxyacetophenone, 2-methyl-2-morpholinyl-1- (4-methylthiophenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinylphenyl) butan-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1, 2-diphenyl-2, 2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1- [ 4- (2-hydroxyethoxy) phenyl ] propan-1-one, 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1- [ 4- (1-methylvinyl) phenyl ] propan-1-one.

Examples of the acylphosphine oxide compound include 2,4, 6-trimethylbenzoyl diphenylphosphine oxide and bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide.

Examples of the triazine compound include 2, 4-bis (trichloromethyl) -6- (4-methoxyphenyl) -1,3, 5-triazine, 2, 4-bis (trichloromethyl) -6- (4-methoxynaphthyl) -1,3, 5-triazine, 2, 4-bis (trichloromethyl) -6- (4-methoxystyryl) -1,3, 5-triazine, 2, 4-bis (trichloromethyl) -6- [ 2- (5-methylfuran-2-yl) vinyl ] -1,3, 5-triazine, 2, 4-bis (trichloromethyl) -6- [ 2- (furan-2-yl) vinyl ] -1,3, 5-triazine, 2, 4-bis (trichloromethyl) -6- [ 2- (4-diethylamino-2-methylphenyl) vinyl ] -1,3, 5-triazine and 2, 4-bis (trichloromethyl) -6- [ 2- (3, 4-dimethoxyphenyl) vinyl ] -1,3, 5-triazine.

As the polymerization initiator, a commercially available polymerization initiator can be used. Examples of the commercially available polymerization initiator include "Irgacure (registered trademark) 907", "Irgacure (registered trademark) 184", "Irgacure (registered trademark) 651", "Irgacure (registered trademark) 819", "Irgacure (registered trademark) 250", "Irgacure (registered trademark) 369" (Ciba Japan corporation); "Seikuol (registered trademark) BZ", "Seikuol (registered trademark) Z", "Seikuol (registered trademark) BEE" (Seikuol chemical Co., ltd.); "kayacure (a registered trademark) BP100" (japan chemical company); "kayacure (registered trademark) UVI-6992" (manufactured by Dow Corp.); "Adecaoptomer SP-152", "Adecaoptomer SP-170" (ADEKA, inc.); "TAZ-A", "TAZ-PP" (Nihon SiberHegner company); and "TAZ-104" (Sanwa Chemical Co.).

When the polymerizable liquid crystal composition contains a polymerization initiator, the content thereof may be appropriately adjusted according to the type and amount of the polymerizable liquid crystal contained in the composition, and is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal. If the content of the polymerizable initiator is within this range, the polymerizable liquid crystal can be polymerized without disturbing the alignment thereof.

In the case where the polymerizable liquid crystal composition contains a photopolymerization initiator, the composition may further contain a photosensitizer. Examples of the photosensitizing agent include xanthone compounds such as xanthone and thioxanthone (e.g., 2, 4-diethylthioxanthone and 2-isopropylthioxanthone); anthracene compounds such as anthracene and alkoxy group-containing anthracene (e.g., dibutoxyanthracene); phenothiazine and rubrene.

When the polymerizable liquid crystal composition contains a photopolymerization initiator and a photosensitizer, the polymerization reaction of the polymerizable liquid crystal contained in the composition can be further promoted. The amount of the photosensitizer to be used is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal, and can be appropriately adjusted depending on the types and amounts of the photopolymerization initiator and the polymerizable liquid crystal.

In order to more stably perform the polymerization reaction of the polymerizable liquid crystal, the polymerizable liquid crystal composition may contain an appropriate amount of a polymerization inhibitor, whereby the degree of the polymerization reaction of the polymerizable liquid crystal can be easily controlled.

Examples of the polymerization inhibitor include radical scavengers such as hydroquinone, alkoxy-containing catechol (e.g., butylcatechol), pyrogallol, and 2, 6-tetramethyl-1-piperidinyloxy radical; thiophenols; beta-naphthylamines and beta-naphthols.

When the polymerizable liquid crystal composition contains a polymerization inhibitor, the content thereof may be appropriately adjusted according to the type and amount of the polymerizable liquid crystal, the amount of the photosensitizer used, and the like, and is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal. If the content of the polymerization inhibitor is within this range, the polymerizable liquid crystal can be polymerized without disturbing the alignment thereof.

[ method for producing retardation film ]

In the case of manufacturing the retardation plate, the order of forming the 1 st retardation layer, the 2 nd retardation layer, and the 3 rd retardation layer is arbitrary. The order of forming the layers a and B in the 1 st retardation layer is arbitrary.

The 2 nd retardation layer may be formed on the substrate with or without the orientation film layer a interposed therebetween, the orientation film layer B interposed therebetween, and the layer B with or without the orientation film interposed therebetween.

The 2 nd retardation layer may be formed on the substrate with or without the orientation film layer B interposed therebetween, the orientation film layer a interposed therebetween or not interposed therebetween, and the layer a interposed therebetween or not interposed therebetween.

The 2 nd retardation layer may be formed on the substrate with or without the orientation film interposed therebetween, the 2 nd retardation layer may be formed with or without the orientation film interposed therebetween to form the layer a, and the layer a may be formed with or without the orientation film interposed therebetween to form the layer B.

The 2 nd retardation layer may be formed on the substrate with or without the orientation film interposed therebetween, the 2 nd retardation layer may be formed with or without the orientation film interposed therebetween to form the layer B, and the layer B may be formed with or without the orientation film interposed therebetween to form the layer a.

The 2 nd retardation layer may be formed on one surface of the substrate with or without the orientation film layer a interposed therebetween, the orientation film layer B interposed therebetween or not interposed therebetween, and the other surface of the substrate with or without the orientation film interposed therebetween.

The 2 nd retardation layer may be formed on one surface of the substrate with or without the orientation film layer B interposed therebetween, the orientation film layer a interposed therebetween or not on the layer B, and the orientation film layer a interposed therebetween or not on the other surface of the substrate.

When the layer a is formed with or without the orientation film interposed therebetween, or when the layer B is formed with or without the orientation film interposed therebetween, a protective layer may be provided between the layer a and the layer B. In addition, a protective layer may be provided between the 2 nd retardation layer and the layer a or the layer B when the 2 nd retardation layer is formed with or without the orientation film layer a interposed therebetween, when the 2 nd retardation layer is formed with or without the orientation film interposed therebetween, or when the 2 nd retardation layer is formed with or without the orientation film interposed therebetween.

The 1 st retardation layer may be formed on the substrate with or without the orientation film interposed therebetween, the 2 nd retardation layer may be formed on the 1 st retardation layer with or without the orientation film interposed therebetween, and the 3 rd retardation layer may be formed on the 2 nd retardation layer with or without the orientation film interposed therebetween.

The 3 rd retardation layer may be formed on the substrate with or without the orientation film interposed therebetween, the 2 nd retardation layer may be formed on the 3 rd retardation layer with or without the orientation film interposed therebetween, and the 1 st retardation layer may be formed on the 2 nd retardation layer with or without the orientation film interposed therebetween. The 1 st retardation layer may be formed on one surface of the substrate with or without an alignment film interposed therebetween, the 2 nd retardation layer may be formed on the 1 st retardation layer with or without an alignment film interposed therebetween, and the 3 rd retardation layer may be formed on the other surface of the substrate with or without an alignment film interposed therebetween.

The 2 nd retardation layer may be formed on one surface of the substrate with or without an alignment film interposed therebetween, the 1 st retardation layer may be formed on the 2 nd retardation layer with or without an alignment film interposed therebetween, and the 3 rd retardation layer may be formed on the other surface of the substrate with or without an alignment film interposed therebetween.

The 3 rd retardation layer may be formed on one surface of the substrate with or without an alignment film interposed therebetween, the 2 nd retardation layer may be formed on the 3 rd retardation layer with or without an alignment film interposed therebetween, and the 1 st retardation layer may be formed on the other surface of the substrate with or without an alignment film interposed therebetween.

The 2 nd retardation layer may be formed on one surface of the substrate with or without an alignment film interposed therebetween, the 3 rd retardation layer may be formed on the 2 nd retardation layer with or without an alignment film interposed therebetween, and the 1 st retardation layer may be formed on the other surface of the substrate with or without an alignment film interposed therebetween.

The 1 st retardation layer may be formed on the substrate with or without the orientation film interposed therebetween, and the 2 nd retardation layer may be formed on the 1 st retardation layer with or without the orientation film interposed therebetween.

The 2 nd retardation layer may be formed on one surface of the substrate with or without the orientation film interposed therebetween, and the 1 st retardation layer may be formed on the 2 nd retardation layer with or without the orientation film interposed therebetween.

The 2 nd retardation layer may be formed on one surface of the substrate with or without the orientation film interposed therebetween, and the 1 st retardation layer may be formed on the other surface of the substrate with or without the orientation film interposed therebetween.

When the 2 nd retardation layer is formed on the 1 st retardation layer with or without the orientation film interposed therebetween, or when the 1 st retardation layer is formed on the 2 nd retardation layer with or without the orientation film interposed therebetween, a protective layer may be provided between the 1 st retardation layer and the 2 nd retardation layer. In addition, when the 3 rd retardation layer is formed on the 2 nd retardation layer with or without the orientation film interposed therebetween, or when the 2 nd retardation layer is formed on the 3 rd retardation layer with or without the orientation film interposed therebetween, a protective layer may be provided between the 2 nd retardation layer and the 3 rd retardation layer.

(protective layer)

The protective layer is preferably formed of a composition for forming a protective layer containing an acrylic oligomer or polymer including a polyfunctional acrylate (methacrylate), a urethane acrylate, a polyester acrylate, an epoxy acrylate, etc., polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, polyvinyl pyrrolidone, starches, methylcellulose, carboxymethylcellulose, sodium alginate, etc., and a solvent.

The solvent contained in the composition for forming a protective layer may be the same solvent as the above solvent, and among them, at least one solvent selected from the group consisting of water, an alcohol solvent and an ether solvent is preferable in that the layer forming the protective layer is not dissolved. Examples of the alcohol solvent include methanol, ethanol, butanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether. Examples of the ether solvent include ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate. Among them, ethanol, isopropanol, propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate are preferable.

The thickness of the protective layer is usually 20 μm or less. The thickness of the protective layer is preferably 0.5 μm or more and 10 μm or less, more preferably 1 μm or more and 5 μm or less. The thickness of the protective layer can be generally obtained by measurement using an interferometer film thickness meter, a laser microscope, or a stylus film thickness meter.

Next, a method of continuously manufacturing the phase difference plate will be described. As a suitable method for continuously producing the present optical film, a method using a roll-to-roll type is mentioned. Here, a method for producing a retardation layer formed by polymerizing a polymerizable liquid crystal will be described, and a retardation layer including a stretched film may be used in addition to a retardation layer formed by polymerizing a polymerizable liquid crystal, and in this case, the "coating polymerizable liquid crystal composition" in the following production steps may be replaced with the "laminated stretched film".

The following is an example of a typical manufacturing method, and other structures may be implemented according to the following manufacturing method.

The following steps are carried out in this order:

(1) A step of preparing a roll for winding the base material on the winding core,

(2) A step of continuously feeding the base material from the roll,

(3) A step of continuously forming an alignment film on the substrate,

(4) A step of continuously forming a 1 st retardation layer by applying a polymerizable liquid crystal composition to the alignment film,

(5) A step of continuously forming a protective layer on the 1 st phase difference layer obtained in the step (4),

(6) A step of continuously forming an alignment film on the protective layer obtained in the step (5),

(7) A step of continuously forming a 2 nd retardation layer by applying a polymerizable liquid crystal composition to the alignment film obtained in the above (6),

(8) And a step of winding the continuously obtained optical film around a 2 nd winding core to obtain a 2 nd roll. The steps (3), (5) and (6) may be omitted as needed, and in this case, the "on the alignment film" in the step (4) may be replaced with the "on the substrate", the "protective layer obtained in the step (5) may be replaced with the" 1 st retardation layer ", and the" alignment film obtained in the step (6) in the step (7) may be replaced with the "1 st retardation layer" or the "protective layer obtained in the step (5)". In order to suppress wrinkles and curls during conveyance, a protective film may be attached during film conveyance in each step.

Further, a method of sequentially performing the following steps is also mentioned:

(1a) A step of preparing a roll for winding the base material on the winding core,

(2a) A step of continuously feeding the base material from the roll,

(3a) A step of continuously forming an alignment film on the substrate,

(4a) A step of applying a polymerizable liquid crystal composition to the alignment film to continuously form a 2 nd retardation layer,

(5a) A step of continuously forming a protective layer on the 2 nd phase difference layer obtained in the step (4 a),

(6a) A step of continuously forming an alignment film on the protective layer obtained in the step (5 a),

(7a) A step of continuously forming a 1 st retardation layer by applying a polymerizable liquid crystal composition to the alignment film obtained in the step (6 a),

(8a) And a step of winding the continuously obtained optical film around a 2 nd winding core to obtain a 2 nd roll. The steps (3 a), (5 a) and (6 a) may be omitted as needed, and in this case, the "on the alignment film" in the step (4 a) may be replaced with the "on the substrate", the "protective layer obtained in the step (5 a) may be replaced with the" 2 nd retardation layer "in the step (6 a), and the" alignment film obtained in the step (6 a) may be replaced with the "2 nd retardation layer" or the "protective layer obtained in the step (5 a)" in the step (7 a). In order to suppress wrinkles and curls during conveyance, a protective film may be attached during film conveyance in each step.

(1b) A step of preparing a roll for winding the base material on the winding core,

(2b) A step of continuously feeding the base material from the roll,

(3b) A step of continuously forming an alignment film on the substrate,

(4b) A step of continuously forming a 1 st retardation layer by applying a polymerizable liquid crystal composition to the alignment film,

(5b) A step of continuously forming an alignment film on the surface of the substrate opposite to the 1 st retardation layer obtained in the above (4 b),

(6b) A step of continuously forming a 2 nd retardation layer by applying a polymerizable liquid crystal composition to the alignment film obtained in the step (5 b),

(7b) And a step of winding the continuously obtained optical film around a 2 nd winding core to obtain a 2 nd roll. The steps (3 b) and (5 b) may be omitted as needed, and in this case, the "on the alignment film" in the step (4 b) may be replaced with the "on the substrate", and the "on the alignment film obtained in the step (5 b) in the step (6 b) may be replaced with the" substrate surface opposite to the 1 st retardation layer obtained in the step (4 b) ". In order to suppress wrinkles and curls during conveyance, a protective film may be attached during film conveyance in each step.

(1c) A step of preparing a roll in which the transparent base material is wound around a winding core,

(2c) A step of continuously feeding the transparent substrate from the roll,

(3c) A step of continuously forming an alignment film on the transparent substrate,

(4c) A step of applying a polymerizable liquid crystal composition to the alignment film to continuously form a 2 nd retardation layer,

(5c) A step of continuously forming an alignment film on the surface of the substrate opposite to the 2 nd retardation layer obtained in the above (4 c),

(6c) A step of continuously forming a 1 st retardation layer by applying a polymerizable liquid crystal composition to the alignment film obtained in the step (5 c),

(7c) And a step of winding the continuously obtained optical film around a 2 nd winding core to obtain a 2 nd roll. The steps (3 c) and (5 c) may be omitted as needed, and in this case, the "on the alignment film" in the step (4 c) may be replaced with the "on the substrate", and the "on the alignment film obtained in the step (5 c) in the step (6 c) may be replaced with the" substrate surface opposite to the 2 nd retardation layer obtained in the step (4 c) ". In order to suppress wrinkles and curls during conveyance, a protective film may be attached during film conveyance in each step.

(1d) A step of preparing a roll for winding the base material on the winding core,

(2d) A step of continuously feeding the base material from the roll,

(3d) A step of continuously forming an alignment film on the substrate,

(4d) A step of continuously forming a layer A by applying a polymerizable liquid crystal composition onto the alignment film,

(5d) A step of continuously forming a protective layer on the layer A obtained in the step (4 d),

(6d) A step of continuously forming an alignment film on the protective layer obtained in the step (5 d),

(7d) A step of continuously forming a layer B by applying a polymerizable liquid crystal composition to the alignment film obtained in the step (6 d),

(8d) A step of continuously forming a protective layer on the layer B obtained in the step (7 d),

(9d) A step of continuously forming an alignment film on the protective layer obtained in the above (8 d),

(10d) A step of continuously forming a 2 nd retardation layer by applying a polymerizable liquid crystal composition to the alignment film obtained in the above (9 d),

(11d) And a step of winding the continuously obtained optical film around a 2 nd winding core to obtain a 2 nd roll. The steps (3 d), (5 d), (6 d), (8 d) and (9 d) may be omitted as needed, and in this case, the "on the alignment film" in the step (4 d) may be replaced with the "on the substrate", the "protective film obtained in the step (5 d) may be replaced with the" layer a ", the" alignment film obtained in the step (6 d) may be replaced with the "layer a" or the "protective film obtained in the step (5 d)" in the step (7 d), the "protective film obtained in the step (8 d) in the step (9 d) may be replaced with the" layer B ", and the" alignment film obtained in the step (9 d) in the step (10 d) may be replaced with the "layer B" or the "protective layer obtained in the step (9 d)". In order to suppress wrinkles and curls during conveyance, a protective film may be attached during film conveyance in each step.

(1e) A step of preparing a roll for winding the base material on the winding core,

(2e) A step of continuously feeding the base material from the roll,

(3e) A step of continuously forming an alignment film on the substrate,

(4e) A step of continuously forming a 1 st retardation layer by applying a polymerizable liquid crystal composition to the alignment film,

(5e) A step of continuously forming a protective layer on the 1 st phase difference layer obtained in the step (4 e),

(6e) A step of continuously forming an alignment film on the protective layer obtained in the step (5 e),

(7e) A step of continuously forming a 2 nd retardation layer by applying a polymerizable liquid crystal composition to the alignment film obtained in the step (6 e),

(8e) A step of continuously forming an alignment film on the surface of the substrate opposite to the 1 st retardation layer obtained in the above (4 e),

(9e) A step of continuously forming a 3 rd retardation layer by applying a polymerizable liquid crystal composition to the alignment film obtained in the above (8 e),

(10e) And a step of winding the continuously obtained optical film around a 2 nd winding core to obtain a 2 nd roll. The steps (3 e), (5 e) and (8 e) may be omitted as needed, and in this case, the "on the alignment film" in the step (4 e) may be replaced with the "on the substrate", the "protective layer obtained in the step (5 e) may be replaced with the" 1 st retardation layer obtained in the step (4 e) "in the step (6 e), and the" on the alignment film obtained in the step (8 e) in the step (9 e) may be replaced with the "substrate surface opposite to the 1 st retardation layer obtained in the step (4 e)". In order to suppress wrinkles and curls during conveyance, a protective film may be attached during film conveyance in each step. In order to suppress wrinkles and curls during conveyance, a protective film may be attached during film conveyance in each step.

Fig. 2 is a schematic cross-sectional view schematically showing a specific example of the phase difference plate 30. Fig. 2 (a) shows a retardation plate 30 in which a 1 st retardation layer 31 and a 2 nd retardation layer 32 are laminated. Fig. 2 (b) shows a retardation plate 30 in which a base material 33, a 1 st retardation layer 31, and a 2 nd retardation layer 32 are laminated in this order. Fig. 2 (c) shows a retardation plate 30 in which a base material 33, a 2 nd retardation layer 32, and a 1 st retardation layer 31 are laminated in this order. Fig. 2 (d) shows a retardation plate 30 in which a 1 st retardation layer 31, a base material 33, and a 2 nd retardation layer are laminated in this order.

By removing the base material from the phase difference plate 30 having the base material 33, the phase difference plate 30 having no base material can be obtained (fig. 2 (a)).

Further, the retardation plate 30 can be manufactured by bonding the base material 33 having the 1 st retardation layer 31 and the base material 33' having the 2 nd retardation layer 32. Specific examples thereof include fig. 2 (e), fig. 2 (f) and fig. 2 (g). In bonding, a bonding layer (hereinafter, a bonding layer used for bonding between layers in the phase difference plate 30 is also referred to as "3 rd bonding layer") may be used.

Fig. 3 is a schematic cross-sectional view schematically showing a specific example of the retardation plate 30 when the 1 st retardation layer is composed of the layer a and the layer B, or when the 3 rd retardation layer is provided. Fig. 3 (a) shows a retardation plate 30 in which a layer a34, a layer B35, and a 2 nd retardation layer 32 are laminated in this order. Fig. 3 (B) shows a retardation plate 30 in which a layer B35, a layer a34, and a 2 nd retardation layer 32 are laminated in this order. Fig. 3 (c) shows a retardation plate 30 in which a base material 33, a layer a34, a layer B35, and a 2 nd retardation layer 32 are laminated in this order. Fig. 3 (d) shows a retardation plate 30 in which a base material 33, a 1 st retardation layer 31, a 2 nd retardation layer 32, and a3 rd retardation layer 38 are laminated in this order. Fig. 3 (e) shows a retardation plate 30 in which a base material 33, a layer B35, a layer a34, and a 2 nd retardation layer 32 are laminated in this order. Fig. 3 (f) shows a retardation plate 30 in which a base material 33, a3 rd retardation layer 38, a 2 nd retardation layer 32, and a 1 st retardation layer 31 are laminated in this order. Fig. 3 (g) shows a retardation plate 30 in which a base material 33, a 2 nd retardation 32, a layer B35, and a layer a34 are laminated in this order. Fig. 3 (h) shows a retardation plate 30 in which a base material 33, a 2 nd retardation 32, a layer a34, and a layer B35 are laminated in this order. By peeling the base material 33 from the phase difference plate 30 having the base material 33, the phase difference plate 30 having no base material 33 can be obtained (fig. 3 (a), (b)).

In the case of a structure including the 1 st retardation layer 31, the layer a34, and the layer B35, or in the case of having the 3 rd retardation layer 33, the respective layers may be laminated on both surfaces of the base material 33. As a specific example, fig. 3 (i) shows a retardation plate 30 in which a 2 nd retardation layer 32, a base material 33, a layer a34, and a layer B35 are laminated in this order. Fig. 3 (j) shows a retardation plate 30 in which a 2 nd retardation layer 32, a base material 33, a layer B35, and a layer a34 are laminated in this order. Fig. 3 (k) shows a retardation plate 30 in which a 1 st retardation layer 31, a base material 33, a3 rd retardation layer 38, and a 2 nd retardation layer 32 are laminated in this order. Fig. 3 (l) shows a retardation plate 30 in which a 1 st retardation layer 31, a base material 33, a 2 nd retardation layer 32, and a3 rd retardation layer 38 are laminated in this order. Fig. 3 (m) shows a retardation plate 30 in which a3 rd retardation layer 38, a base material 33, a 1 st retardation layer 31, and a 2 nd retardation layer 32 are laminated in this order. Fig. 3 (n) shows a retardation plate 30 in which a3 rd retardation layer 38, a base material 33, a 2 nd retardation layer 32, and a 1 st retardation layer 31 are laminated in this order. The 2 nd retardation layer 32, the layer a34, and the layer B35 may be formed by direct coating on each layer, may be bonded by bonding after each layer is manufactured, or may be laminated by sequentially transferring each layer.

The retardation plate 30 may have a structure in which another layer is interposed between the 1 st retardation layer 31 and the 2 nd retardation layer 32, or may have a structure in which another layer is not interposed. Examples of the other layer interposed therebetween include the base material 33, the protective layer, the alignment film, and the 3 rd bonding layer. In the retardation plate 30, in a structure having only an alignment film as an interposed other layer and no other layer interposed between the 1 st retardation layer 31 and the 2 nd retardation layer 32, the peel strength between the 1 st retardation layer 31 and the 2 nd retardation layer 32 is easily 1.0N/25mm or less. In the present specification, the layer sandwiched between the 1 st retardation layer 31 and the 2 nd retardation layer 32 means a layer sandwiched between the outermost surface of the 1 st retardation layer 31 on the 2 nd retardation layer 32 side and the outermost surface of the 2 nd retardation layer 32 on the 1 st retardation layer 31 side. Therefore, in the case where the 1 st retardation layer 31 is constituted by the layer a and the layer B, the layer sandwiched between the layer a and the layer B is not regarded as the layer sandwiched between the 1 st retardation layer 31 and the 2 nd retardation layer 32.

[ laminating layer 2, laminating layer 3 ]

The 2 nd bonding layer is a bonding layer for bonding layers to each other in the linear polarizing plate 10, and the 3 rd bonding layer is a bonding layer for bonding layers to each other in the phase difference plate 30. Hereinafter, the term "lamination layer" also includes any of the 2 nd lamination layer and the 3 rd lamination layer.

The adhesive layer is an adhesive layer formed using an adhesive composition or an adhesive layer formed using an adhesive composition. From the viewpoint of suppressing the heat shrinkage behavior upon application of heat, the 2 nd and 3 rd bonding layers are preferably adhesive layers.

In the case where the adhesive layer is an adhesive layer, the adhesive composition used for forming the adhesive layer is not particularly limited as long as the moisture permeability is satisfied. The pressure-sensitive adhesive composition may contain, for example, a rubber-based polymer, a (meth) acrylic polymer, a urethane-based polymer, a polyester-based polymer, a silicone-based polymer, a polyvinyl ether-based polymer, a polyvinyl alcohol-based polymer, a polyolefin-based polymer, a vinyl alkyl ether-based polymer, a polyvinylpyrrolidone-based polymer, a poly (meth) acrylamide-based polymer, a cellulose-based polymer, or the like as a main component. In the present specification, the main component means that 50 mass% or more of the total solid content of the adhesive composition is contained. The adhesive composition may be an active energy ray-curable type or a thermosetting type. The adhesive composition is preferably a rubber-based polymer. The term "(meth) acrylic acid" means "at least 1% of acrylic acid and methacrylic acid". The same applies to "(meth) acrylate" and the like.

The rubber-based polymer may be natural rubber; synthetic rubbers such as polyisobutylene rubber (PIB), isoprene Rubber (IR), isobutylene-isoprene rubber (IIR), n-butene-isobutylene copolymer rubber, butadiene Rubber (BR), chloroprene Rubber (CR), acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-styrene block copolymer rubber (SIBS), styrene-ethylene-butene-styrene block copolymer rubber (SEBS), styrene-ethylene-propylene-styrene block copolymer rubber (SEPS), styrene-butadiene-styrene block copolymer rubber (SBS), and styrene-ethylene-propylene block copolymer rubber (SEP). The rubber-based polymer is preferably polyisobutylene rubber (PIB), isobutylene-isoprene rubber (IIR), or n-butene-isobutylene copolymer rubber, more preferably polyisobutylene rubber (PIB).

As the (meth) acrylic polymer, a polymer or copolymer containing 1 or more than 2 (meth) acrylic esters such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate as monomers is suitably used. The polar monomer is preferably copolymerized with the base polymer. Examples of the polar monomer include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, and the like, such as (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, N-dimethylaminoethyl (meth) acrylate, and glycidyl (meth) acrylate.

The active energy ray-curable pressure-sensitive adhesive composition is a pressure-sensitive adhesive composition which has a property of being cured by irradiation with active energy rays such as ultraviolet rays and electron beams, and has a property of being capable of adhering to an adherend such as a film even before irradiation with active energy rays and being cured by irradiation with active energy rays, thereby being capable of adjusting an adhering force. The active energy ray-curable adhesive composition is preferably an ultraviolet ray-curable adhesive composition. The active energy ray-curable adhesive composition contains an active energy ray-polymerizable compound in addition to the base polymer and the crosslinking agent. A photopolymerization initiator, a photosensitizer, and the like may be further contained as needed.

The adhesive composition may contain a solvent in addition to the polymer; additives such as tackifiers, softeners, fillers (metal powders, other inorganic powders, etc.), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, defoamers, anticorrosive agents, photopolymerization initiators, and the like. When the active energy ray-curable adhesive composition is used, a cured product having a desired degree of cure can be produced by irradiating the formed adhesive layer with active energy rays.

The adhesive layer may be formed by applying an organic solvent dilution of the above adhesive composition to a substrate and drying.

In the case where the adhesive layer is an adhesive layer, the adhesive composition used for forming the adhesive layer is not particularly limited as long as the moisture permeability is satisfied. Examples of the adhesive composition include aqueous adhesives, active energy ray-curable adhesives, natural rubber adhesives, α -olefin adhesives, urethane resin adhesives, ethylene-vinyl acetate resin emulsion adhesives, ethylene-vinyl acetate resin adhesives, epoxy resin adhesives, vinyl chloride resin solvent adhesives, chloroprene rubber adhesives, cyanoacrylate adhesives, silicone adhesives, styrene-butadiene rubber solvent adhesives, nitrile rubber adhesives, nitrocellulose adhesives, reactive hot melt adhesives, phenolic resin adhesives, modified silicone adhesives, polyester hot melt adhesives, polyamide resin hot melt adhesives, polyimide resin adhesives, polyurethane resin hot melt adhesives, polyolefin resin hot melt adhesives, polyvinyl acetate resin solvent adhesives, polystyrene resin solvent adhesives, polyvinyl pyrrolidone resin adhesives, polyvinyl butyral adhesives, polybenzimidazole adhesives, polymethacrylate resin solvent adhesives, urea resin adhesives, melamine resin adhesives, and the like. Such an adhesive may be used alone or in combination of 1 or more than 2 kinds.

Examples of the aqueous adhesive include an aqueous polyvinyl alcohol resin solution and an aqueous two-part urethane emulsion adhesive. The active energy ray-curable adhesive is an adhesive cured by irradiation with active energy rays such as ultraviolet rays, and examples thereof include adhesives containing a polymerizable compound and a photopolymerization initiator, adhesives containing a photoreactive resin, adhesives containing a binder resin and a photoreactive crosslinking agent, and the like. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable (meth) acrylic monomers and photocurable urethane monomers, and oligomers derived from these monomers. The photopolymerization initiator includes those which generate active species such as neutral radicals, anionic radicals, and cationic radicals by irradiation with active energy rays such as ultraviolet rays.

The thickness of the adhesive layer is not particularly limited, and when the adhesive layer is a pressure-sensitive adhesive layer, the thickness is preferably 5 μm or more, and may be 15 μm or more, and may be 20 μm or more, and may be 25 μm or more, and typically 200 μm or less, and may be 100 μm or less, and may be 50 μm or less. When the adhesive layer is used as the bonding layer, the thickness of the bonding layer is preferably 0.01 μm or more, may be 0.05 μm or more, may be 0.5 μm or more, and is preferably 5 μm or less, may be 3 μm or less, or may be 2 μm or less.

[ method for producing polarizing plate ]

The polarizing plate of the present embodiment can be obtained by bonding the retardation plate and the linear polarizing plate using the 1 st bonding layer. When the 1 st retardation layer of the retardation plate is composed of only one layer and there is only one slow axis, it is preferable that the transmission axis of the linear polarizing plate is set so as to substantially reach 45 ° with respect to the slow axis (optical axis) of the 1 st retardation layer of the retardation plate. Substantially 45 ° is typically in the range of 45±5°. In such an angular arrangement, the polarizing plate may function as a circular polarizing plate.

Examples of the method of bonding a retardation plate having no base material to a linear polarizing plate include a method of bonding a retardation plate having no base material to a linear polarizing plate using a 1 st bonding layer and a method of bonding a retardation plate to a linear polarizing plate using a 1 st bonding layer and then removing the base material. In this case, the 1 st adhesive layer may be directly formed by applying an adhesive to the retardation layer side of the retardation plate, may be directly formed by applying an adhesive to the linear polarizing plate side, or may be formed by interposing a 1 st adhesive layer formed in advance on another substrate between the linear polarizing plate and the retardation plate. When an alignment film is present between the base material and the retardation layer, the alignment film may be removed together with the base material.

A substrate having a functional group on the surface thereof, which forms a chemical bond with a retardation layer, an alignment film, or the like, tends to form a chemical bond with a retardation layer, an alignment film, or the like, and is difficult to remove. Therefore, in the case of peeling off and removing the substrate, a substrate having a small number of functional groups on the surface is preferable, and a substrate having no surface treatment for forming functional groups on the surface is preferable.

In addition, since the orientation film having a functional group forming a chemical bond with the substrate tends to have an increased adhesion force between the substrate and the orientation film, when the substrate is peeled off and removed, the orientation film having a small number of functional groups forming a chemical bond with the substrate is preferable. In addition, it is preferable that the solution does not contain a reagent for crosslinking the substrate and the alignment film, and the solution of the alignment polymer composition, the composition for forming a photo-alignment film, and the like does not contain a component such as a solvent for dissolving the substrate.

In addition, the alignment film having a functional group forming a chemical bond with the retardation layer tends to have an increased adhesion force between the retardation layer and the alignment film. Therefore, when the alignment film is removed together with the substrate, the alignment film having fewer functional groups forming chemical bonds with the retardation layer is preferable. In addition, it is preferable that the retardation layer and the alignment film do not contain a reagent for crosslinking the retardation layer and the alignment film.

In addition, the retardation layer having a functional group forming a chemical bond with the alignment film tends to increase adhesion between the alignment film and the retardation layer. Therefore, when the substrate is removed or when the alignment film is removed together with the substrate, the retardation layer having fewer functional groups forming chemical bonds with the substrate or the alignment film is preferable. The polymerizable liquid crystal composition preferably does not contain a reagent for crosslinking the base material or the alignment film with the retardation layer.

For example, the 1 st bonding layer 21 is bonded to the surface of the 1 st phase difference layer 31 of the phase difference plate 30 in which the base material, the 2 nd phase difference layer 32, and the 1 st phase difference layer 31 are sequentially laminated, the linear polarizing plate 10 is bonded thereto, and then the base material of the phase difference plate 30 is removed, whereby the polarizing plate having the configuration shown in fig. 1 in which the linear polarizing plate 10, the 1 st bonding layer 21, the 1 st phase difference layer 31, and the 2 nd phase difference layer 32 are sequentially laminated can be manufactured. Further, a 1 st bonding layer is attached to the surface of a 2 nd retardation layer of a retardation plate in which a base material, a 1 st retardation layer, and a 2 nd retardation layer are sequentially laminated, a linear polarizing plate is bonded thereto, and then the base material of the retardation plate is removed, whereby a polarizing plate in which a linear polarizing plate, a 2 nd retardation layer, and a 1 st retardation layer are sequentially laminated can be manufactured. From the viewpoint of film formation, the substrate is preferably peeled off.

When the 1 st retardation layer includes the layers a and B or when the 3 rd retardation layer is included, the lamination direction of each layer is limited.

Specifically, when the layer a having a phase difference of λ/4 and the layer B having a phase difference of λ/2 are laminated, the layer B is first formed so that the slow axis of the layer B becomes 75 ° with respect to the absorption axis of the linear polarizing plate, and then the layer a is formed so that the slow axis of the layer a becomes 15 °.

In the case of providing the 1 st retardation layer having a retardation of λ/4 and the 3 rd retardation layer having a retardation of λ/2, the 3 rd retardation layer is first formed so that the slow axis of the 3 rd retardation layer becomes 75 ° with respect to the absorption axis of the linear polarizing plate, and then the 1 st retardation layer is formed so that the slow axis of the 1 st retardation layer becomes 15 °. The position of the 2 nd retardation layer is not limited, but it is necessary to sequentially laminate the linear polarizing plate, the layer B and the layer a, or sequentially laminate the linear polarizing plate, the 3 rd retardation layer and the 1 st retardation layer. By laminating in this manner, the obtained polarizing plate can exhibit a function as a wide-band circular polarizing plate. Here, the axial angle of the layers a and B is not limited, and for example, as described in japanese patent application laid-open No. 2004-126538, it is known that even if the slow axial angle of the layers a and B is set to 30 ° and-30 °, or 45 ° and-45 ° with respect to the absorption axis of the polarizing plate, the layers can exhibit the function as a wide-band λ/4 plate, and thus the layers can be laminated by a desired method.

[ image display device ]

Fig. 4 is a schematic cross-sectional view schematically showing an example of the image display device according to the present embodiment. As shown in fig. 4, the image display device 2 includes the polarizing plate 1 and the image display panel 40 shown in fig. 1 in this order from the front side. In the image display device 2, the polarizing plate 1 is disposed in an orientation in which the linear polarizing plate 10 side is positioned further toward the front side than the phase difference plate 30.

In the case where the polarizing plate 1 is a circular polarizing plate, in the image display device 2, there are light reflected by the polarizing plate 1 and light transmitted through the polarizing plate 1 as incident light from the outside. The polarizing plate 1 may have an antireflection layer at the forefront, and by providing the antireflection layer, light reflected on the surface of the polarizing plate 1 (hereinafter, also referred to as "external reflected light") can be reduced. The light transmitted through the polarizing plate 1 is reflected by the image display panel 40 to become reflected light (hereinafter, also referred to as "internal reflected light") and is absorbed by the polarizing plate 1. The internally reflected light is preferably absorbed entirely by the polarizing plate 1, but a part is emitted from the front (hereinafter, this light is also referred to as "emitted internally reflected light").

The polarizing plate 1 may be configured to have an adhesive layer on the rear surface thereof, which can be used to attach the polarizing plate 1 to the image display panel 40.

< other layers that the image display device may have >

The image display device 2 may have layers other than the above layers. Hereinafter, other layers that the image display device 2 may have are exemplified.

(touch sensor Panel)

The touch sensor panel is a device (sensor) for detecting (sensing) a finger or the like in contact with (touching) a screen of the image display device, and is used as an input means for detecting the position of the finger on the screen and inputting the position to the image display device. The touch sensor panel may be disposed between the polarizing plate 1 and the image display panel 40, or may be disposed on the front surface side of the polarizing plate 1. The touch sensor panel is not limited to a detection method as long as it is a sensor capable of detecting a touched position, and examples thereof include a resistive film type, a capacitive coupling type, a photosensor type, an ultrasonic type, an electromagnetic induction coupling type, a surface elastic wave type, an infrared type, and the like. The touch sensor panel using the resistive film system or the capacitive coupling system is suitable because of low cost.

An example of a resistive touch sensor panel is composed of a pair of substrates disposed opposite to each other, an insulating spacer sandwiched between the pair of substrates, a transparent conductive film provided as a resistive film on the front surface of the inner side of each substrate, and a touch position detection circuit. In an image display device provided with a resistive film type touch sensor panel, if the surface of a front panel is touched, the opposing resistive film is shorted, and a current flows through the resistive film. The touch position detection circuit detects a change in voltage at this time, and detects a touched position.

An example of a capacitive-coupling type touch sensor panel is composed of a substrate, a transparent electrode for detecting a position provided on the entire surface of the substrate, and a touch position detection circuit. In an image display device provided with a capacitive coupling type touch sensor panel, if the surface of the front panel is touched, a transparent electrode is grounded via the capacitance of the human body at the point of touch. The touch position detection circuit detects the grounding of the transparent electrode and detects the touched position. The capacitive touch sensor panel is divided into an active region and an inactive region located at the outer periphery of the active region. The active region is a region corresponding to a region (display portion) in which a screen is displayed on the display panel, and the inactive region is a region corresponding to a region (non-display portion) in which a screen is not displayed on the display device, in which a touch by a user is sensed.

The thickness of the touch sensor panel may be, for example, 5 μm or more and 2000 μm or less, or may be 5 μm or more and 100 μm or less.

Flexible image display device

The image display device may be a flexible image display device. The flexible image display device is a bendable image display device. The flexible image display device includes a bendable image display element in which an optical fingerprint authentication system is incorporated, and the polarizing plate of the present invention. The bendable image display element is, for example, an organic EL display panel. The polarizing plate of the present invention is disposed on the viewing side with respect to the organic EL display panel, and is configured to be bendable. The polarizing plate for a flexible image display device may further include a front panel and a touch sensor panel.

The front panel, the polarizing plate of the present invention, and the touch sensor panel are preferably laminated in this order from the viewing side, or the front panel, the touch sensor panel, and the polarizing plate of the present invention are preferably laminated in this order from the viewing side. If the polarizing plate is present on the observation side with respect to the touch sensor panel, the pattern of the touch sensor panel is not easily observed, and as a result, the visibility of the display image is improved, and therefore, it is more preferable to have a structure in which the polarizing plate of the present invention is provided on the observation side with respect to the touch sensor panel, that is, to have the front panel, the polarizing plate of the present invention, and the touch sensor panel in this order. The members may be laminated using an adhesive, a binder, or the like. The touch sensor panel may further include a light shielding pattern formed on at least one surface of any one of the front panel, the polarizing plate, and the touch sensor panel.

In a flexible image display device including a front panel, the polarizing plate of the present invention, and a bendable image display panel from the viewing side, the front panel and the polarizing plate of the present invention constitute a polarizing plate with a front panel including the polarizing plate and the front panel. In this polarizing plate with a front panel, the front panel is generally disposed on the viewing side of the polarizing plate, and is laminated with the polarizing plate, for example, with an adhesive or an adhesive.

In a flexible image display device including a touch sensor panel, the polarizing plate of the present invention, and a bendable image display panel from the observation side, the touch sensor panel and the polarizing plate of the present invention constitute a polarizing plate with a touch sensor panel including the polarizing plate and the touch sensor panel. In a flexible image display device including the polarizing plate, the touch sensor panel, and the bendable image display element according to the present invention from the observation side, the touch sensor panel and the polarizing plate according to the present invention constitute a polarizing plate with a touch sensor panel including the polarizing plate and the touch sensor panel. In the polarizing plate with a touch sensor panel, the touch sensor panel may be disposed on the back side (opposite side to the observation side) of the polarizing plate or may be disposed on the observation side of the polarizing plate. The touch sensor panel and the polarizing plate are laminated, for example, by an adhesive or an adhesive.

The polarizing plate of the present invention may be used as a polarizing plate with a front plate by laminating a front plate on the viewing side. The polarizing plate with a front panel includes the polarizing plate of the present invention and a front panel disposed on the observation side.

(front panel)

Examples of the front panel include a front panel including a hard coat layer on at least one surface of glass or a resin film. As the glass, for example, a high-transmission glass or a reinforced glass can be used. In the case of using a particularly thin transparent surface material, a chemically strengthened glass is preferably used. The thickness of the glass may be, for example, 100 μm to 5mm.

The front panel including the hard coat layer on at least one surface of the resin film may have a flexible characteristic, not as rigid as conventional glass. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 μm to 100 μm.

Examples of the resin film include films formed of polymers such as cycloolefin derivatives having a unit including a cycloolefin such as norbornene or polycyclic norbornene-based monomer, cellulose (diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl cellulose, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose), ethylene-vinyl acetate copolymer, polycycloolefin, polyester, polystyrene, polyamide, polyetherimide, polyacrylic acid, polyimide, polyamideimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, and epoxy resin. These polymers may be used alone or in combination of 2 or more.

The resin film may be an unstretched film or a stretched film, for example, a uniaxially stretched film or a biaxially stretched film. The resin film is preferably a polyamide imide film, a polyimide film, a uniaxially stretched polyester film, or a biaxially stretched polyester film, in view of its excellent transparency and heat resistance, and in view of its capability of coping with an increase in film size, a cycloolefin derivative film or a polymethyl methacrylate film, and in view of its relatively easy availability of a resin film having no transparency and no optical anisotropy, triacetyl cellulose and isobutyl cellulose films are preferred, respectively. The thickness of the resin film is usually 5 to 200. Mu.m, preferably 20 to 100. Mu.m.

(shading pattern)

The light shielding pattern is a member also called a bezel, and may be formed on the display element side of the front panel. By providing the light shielding pattern, each wiring constituting the display device can be hidden from the user. The color and material of the light shielding pattern are not particularly limited, and may be formed of a resin material having a plurality of colors such as black, white, gold, and the like. In one embodiment, the thickness of the light shielding pattern may be 2 μm to 50 μm, preferably 4 μm to 30 μm, and more preferably 6 μm to 15 μm. In addition, in order to suppress the mixing of bubbles and the visibility of the boundary portion due to the level difference between the light shielding pattern and the display portion, a shape may be given to the light shielding pattern.

Examples

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. The amounts of "%" and "parts" in examples and comparative examples are mass% and parts unless otherwise specified.

(1) Preparation of active energy ray-curable adhesive

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

Active energy ray-curable adhesive A >, adhesive for curing

3, 4-epoxycyclohexane carboxylic acid 3',4' -epoxycyclohexyl methyl ester (trade name: CEL2021P, manufactured by Daicel Co., ltd.): 70 parts by mass

Neopentyl glycol diglycidyl ether (trade name: EX-211,Nagase ChemteX Co., ltd.): 20 parts by mass

2-ethylhexyl glycidyl ether (trade name: EX-121,Nagase ChemteX Co., ltd.): 10 parts by mass

Cationic polymerization initiator (trade name: CPI-100_50% solution, manufactured by San-Apro Co., ltd.): 4.5 parts by mass (substantially solid component 2.25 parts by mass)

1, 4-diethoxynaphthalene: 2 parts by mass

Active energy ray-curable adhesive B

Neopentyl glycol diglycidyl ether (trade name: EX-211L,Nagase ChemteX Co., ltd.): 30 parts by mass

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

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

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

1, 4-diethoxynaphthalene: 1 part by mass

Active energy ray-curable adhesive C

N, N-dimethylacrylamide (manufactured by KJ Chemicals Co., ltd.): 7 parts by weight

4-hydroxybutyl acrylate (Osaka organic industries Co.): 55 parts by weight

1, 4-cyclohexanedimethanol monoacrylate (Japanese chemical Co., ltd.): 28 parts by weight

Ultraviolet curable urethane acrylate resin (trade name: UV-3000B, japan chemical Co., ltd.): 10 parts by weight

2-hydroxy-2-methyl-1-phenylpropan-1-one (trade name: DAROCUR 1173, BASF Japan Co., ltd.): 3 parts by weight

< determination of tensile storage modulus of adhesive layer >)

In the shape of a ring having a thickness of 50 μmThe adhesive composition (active energy ray-curable adhesives a to C) was applied to one side of the polyolefin resin film using a bar coater manufactured by first chemical company, using a bar #18, so that the thickness became 25 μm. Next, in the "Fusion UV lamp system" manufactured by Fusion UV Systems, the lamp was "DBulb" so that the cumulative light amount of UVA in the UV wavelength region became 3000mJ/cm ² Ultraviolet rays were irradiated to the atmosphere having a relative humidity of 60% RH at 25℃based on the measured value of UV Power PuckII manufactured by Fusion UV Systems Co. Then, the mixture was left to stand in an atmosphere having a relative humidity of 60% RH at 25℃for 48 hours under darkening, and the adhesive was cured. The resultant was cut into a size of 5mm×30mm, and the cyclic polyolefin resin film was peeled off to obtain a cured film of the adhesive.

The cured film of the adhesive obtained as described above was held at a gap of 2cm between clamps using a dynamic viscoelasticity measuring device "DVA-220" manufactured by IT meter control Co., ltd. So that the long side thereof became the stretching direction, the frequency of stretching and shrinkage was set to 10Hz, the measurement temperature was set to 23℃and the tensile storage modulus at the temperature of 23℃was obtained. The tensile storage moduli of the adhesive layers a to C are the adhesive layer a: 2.1X10 times ³ MPa, adhesive layer B: 2.4X10 ³ MPa, adhesive layer C:0.56MPa.

(2) Preparation of adhesive layer

The following acrylic pressure-sensitive adhesive layers (1) to (3) were prepared, both of which were bonded to a release film.

< adhesive layer (1) >)

(2-1-1) preparation of acrylic resin solution 1

A mixed solution of 100 parts of ethyl acetate, 99.0 parts of butyl acrylate, 0.5 parts of 2-hydroxyethyl acrylate and 0.5 parts of acrylic acid was charged into a reaction vessel equipped with a condenser, a nitrogen inlet, a thermometer and a stirrer, and the internal temperature was raised to 55℃while the air in the apparatus was replaced with nitrogen gas to remove oxygen. Then, a solution of 0.12 part of azobisisobutyronitrile (polymerization initiator) dissolved in 10 parts of ethyl acetate was added in the entire amount. After adding the polymerization initiator, the mixture is kept at that temperature for 1 hour, and then the internal temperature is kept at 54 to 5While continuously adding ethyl acetate to the reaction vessel at a rate of 17.3 parts/hr at 6℃and at the time when the concentration of the (meth) acrylic resin became 35 mass%, the addition of ethyl acetate was stopped, and the reaction vessel was further incubated at this temperature until 6 hours passed from the start of the addition of ethyl acetate. Finally, ethyl acetate was added thereto to adjust the concentration of the (meth) acrylic resin to 20 mass%, thereby preparing an acrylic resin solution 1. The weight average molecular weight Mw of the resulting acrylic resin was 170 million, and the molecular weight distribution Mw/Mn was 3.9. Incidentally, mw and Mn are measured by: 2 TSKgel GMH manufactured by Tosoh corporation are connected in series in GPC apparatus _HR H (S) "as a column, tetrahydrofuran as an eluent, and the concentration of the sample was 2mg/mL, the amount of the sample introduced was 100. Mu.L, the temperature was 40℃and the flow rate was 1 mL/min, and the measurement was carried out by standard polystyrene conversion.

(2-1-2) preparation of adhesive composition 1

To 80 parts of the solid content of the acrylic resin solution 1 obtained in (2-1-1), 20 parts (solid content) of a difunctional acrylate (available from Xinzhou chemical industry Co., ltd.; product No. A-DOG "), 2.5 parts (product name" Coronate L "(ethyl acetate solution of trimethylolpropane adduct of toluene diisocyanate (solid content concentration: 75 mass%) manufactured by Tosoh Co., ltd.), 1.5 parts (product name" Irgacure500 manufactured by Ciba Specialty Chemicals Co., ltd.), 0.3 parts (product name "KBM-403" manufactured by Xinyue chemical industry Co., ltd.), and ethyl acetate were added so that the solid content concentration became 13%, whereby an adhesive composition 1 was obtained.

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

[ chemical formula 18]

(2-1-3) preparation of adhesive layer (1)

The adhesive composition 1 prepared in the above (2-1-2) was applied to a release treated surface of a release film comprising a polyethylene terephthalate film (PLZ-383030, available from Wandeke Co., ltd.) subjected to a release treatment so that the thickness after drying became 5 μm using an applicator, and dried at 100℃for 1 minute to prepare an adhesive layer (adhesive sheet). Then, the surface of the obtained pressure-sensitive adhesive layer opposite to the separator was bonded to a release-treated surface of a separator [ PLR-381031 "obtained from Wandeke Co., ltd.) comprising a polyethylene terephthalate film subjected to a release treatment. Next, ultraviolet rays were irradiated under the following conditions to produce an adhesive layer (1). The resulting adhesive layer had a shear storage modulus of 0.13MPa at a temperature of 23 ℃.

< UV irradiation Condition >)

H Bulb using Fusion UV lamp System (manufactured by Fusion UV Systems Co.)

Cumulative light quantity of UVA in UV wavelength region 250mJ/cm ² ( Based on the determinator: measurement value of UV Power PuckII manufactured by fusion UV Co )

< adhesive layer (2) >)

(2-2-1) preparation of acrylic resin solution 2

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

(2-2-2) preparation of adhesive composition 2

To 100 parts of the solid content of the acrylic resin solution 2 obtained in (2-2-1), 0.15 part of a crosslinking agent (trade name "Coronate L" (ethyl acetate solution of trimethylolpropane adduct of toluene diisocyanate (solid content concentration 75 mass%)) and 0.2 part of a silane coupling agent (trade name "KBM-403" by Xin Yue chemical industries Co., ltd.) were added based on the active ingredient, and ethyl acetate was further added so that the solid content concentration became 13%, to obtain an adhesive composition 2.

(2-2-3) preparation of adhesive layer (2)

The pressure-sensitive adhesive composition 2 prepared in the above (2-2-2) was applied to a release treated surface of a release treated film comprising a polyethylene terephthalate film (PLR-382190, available from Wandeke Co., ltd.) which was subjected to release treatment so that the thickness thereof after drying became 25 μm using an applicator, and dried at 100℃for 1 minute to prepare a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet). Then, the surface of the obtained pressure-sensitive adhesive layer opposite to the separator was bonded to a release-treated surface of a separator (PET-251130, obtained from lindaceae) containing a polyethylene terephthalate film, which was subjected to a release treatment, to prepare a pressure-sensitive adhesive layer (2). The resulting adhesive layer had a shear storage modulus of 0.026MPa at a temperature of 23 ℃.

< adhesive layer (3) >)

(2-3-1) preparation of acrylic resin solution 3

Comprising a condenser tube, a nitrogen inlet tube, a thermometer and stirringA mixed solution of 91 parts of ethyl acetate, 43 parts of 2-ethylhexyl acrylate, 55 parts of butyl acrylate and 2.0 parts of 2-hydroxyethyl acrylate was charged into a reaction vessel of the apparatus, and the internal temperature was raised to 55℃while the air in the apparatus was replaced with nitrogen gas to remove oxygen. Then, a solution of 0.14 parts of azobisisobutyronitrile (polymerization initiator) dissolved in 10 parts of ethyl acetate was added in the entire amount. After the addition of the polymerization initiator, the reaction vessel was continuously charged with ethyl acetate while maintaining the internal temperature at 54 to 56℃for 1 hour, and the addition of ethyl acetate was stopped at a point in time when the concentration of the (meth) acrylic resin became 35 mass%, and the reaction vessel was further kept at that temperature until 10 hours passed from the start of the addition of ethyl acetate. Finally, ethyl acetate was added thereto to adjust the concentration of the (meth) acrylic resin to 20 mass%, thereby preparing an acrylic resin solution 3. The weight average molecular weight Mw of the resulting acrylic resin was 110 million, and the molecular weight distribution Mw/Mn was 4.8. Incidentally, mw and Mn are measured by: 2 TSKgel GMH manufactured by Tosoh corporation are connected in series in GPC apparatus _HR H (S) "as a column, tetrahydrofuran as an eluent, and the concentration of the sample was 2mg/mL, the amount of the sample introduced was 100. Mu.L, the temperature was 40℃and the flow rate was 1 mL/min, and the measurement was carried out by standard polystyrene conversion.

(2-3-2) preparation of adhesive composition 3

To 100 parts of the solid content of the acrylic resin solution 3 obtained in (2-3-1), 0.3 part of a crosslinking agent (trade name "Coronate L" (ethyl acetate solution of trimethylolpropane adduct of toluene diisocyanate (solid content concentration 75 mass%)) and 0.25 part of a silane coupling agent (trade name "KBM-403" by Xin Yue chemical industries Co., ltd.) were added based on the active ingredient, and ethyl acetate was further added so that the solid content concentration became 15%, to obtain an adhesive composition 3.

(2-3-3) preparation of adhesive layer (3)

The adhesive composition 3 prepared in the above (2-3-2) was applied to a release treated surface of a release treated film comprising a polyethylene terephthalate film (POGW-502190, available from Wandeke Co., ltd.) which was subjected to release treatment so that the thickness thereof after drying became 25 μm using an applicator, and dried at 100℃for 1 minute to prepare an adhesive layer (adhesive sheet). Then, the surface of the obtained pressure-sensitive adhesive layer opposite to the separator was bonded to a release-treated surface of a separator (PLR-381031, obtained from Lindeke Co., ltd.) comprising a polyethylene terephthalate film subjected to a release treatment, to prepare a pressure-sensitive adhesive layer (3). The resulting adhesive layer had a shear storage modulus of 0.01MPa at a temperature of 23 ℃.

< determination of shear storage modulus of adhesive layer and conversion to tensile storage modulus >)

The shear storage modulus of the adhesive layer was measured using a viscoelasticity measuring device (MCR-301, anton Paar Co.). The adhesive layers similar to those used in examples and comparative examples were each 30mm wide by 30mm long, and after a plurality of release films were laminated so as to have a thickness of 200 μm and bonded to a measurement stage, the release films were measured in a state of being bonded to a measurement chip (PP 25, anton Paar corporation) under conditions of a temperature range of-20 to 100 ℃, a frequency of 1.0Hz, a deformation amount of 1%, a normal force of 1N, and a heating rate of 5 ℃/min. The shear storage modulus obtained here was converted based on the formula (10), and a tensile storage modulus at a temperature of 23℃was obtained.

E=gx2× (1+v) formula (10)

Here, E is the tensile storage modulus, G is the shear storage modulus, and v is the poisson's ratio. In the present specification, the poisson's ratio of the adhesive was treated as 0.5 (see book name "lecture-rheology" (editor: japanese rheology society, issuer: western gatekeeper, issuer: high molecular periodical society, co., ltd.), page 15 (1.12)).

(3) Manufacture of polarizer

A polyvinyl alcohol film having a thickness of 20 μm, a polymerization degree of 2400, and a saponification degree of 99% or more was uniaxially stretched on a hot roll to a stretching ratio of 4.5 times, and was immersed in a dyeing bath containing 0.05 part by mass of iodine and 5 parts by mass of potassium iodide per 100 parts by mass of water in a state of being kept under tension at 28℃for 60 seconds.

Next, the solution was immersed in an aqueous boric acid solution 1 containing 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water at 64 ℃ for 110 seconds. Next, the solution was immersed in an aqueous boric acid solution 2 containing 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water at 67 ℃ for 30 seconds. Then, the resultant was washed with pure water at 10℃and dried to obtain a polarizing plate. The thickness of the polarizing plate was 8 μm and the boron content was 4.3 mass%.

(4) Preparation of protective film

The following protective films were prepared.

Protective film: norbornene resin film having a thickness of 13 μm (trade name "ZEONOR", manufactured by Japanese ZEON Co., ltd.).

(5) Production of Linear polarizing plate

The protective film was bonded to one surface of the produced polarizing plate by using a roll bonding machine with an aqueous adhesive. After the lamination, the lamination was dried at 80℃for 3 minutes. A linear polarizing plate in which a protective film was laminated on only one side of a polarizing plate was obtained. The linear polarizing plate is sequentially laminated with a polarizing plate, an adhesive layer, and a protective film.

(6) Fabrication of 1 st phase-difference layer

(i) Preparation of composition for Forming photo-alignment film

5 parts (weight average molecular weight: 30000) of a photo-alignment material having the following structure was mixed with 95 parts of cyclopentanone (solvent). The resulting mixture was stirred at 80℃for 1 hour, whereby a composition for forming a photo-alignment film was obtained.

[ chemical formula 19]

(ii) Preparation of composition for Forming No. 1 phase-difference layer

The polymerizable liquid crystal compound a and the polymerizable liquid crystal compound B shown below were mixed at 90:10 mass ratio. To 100 parts of the mixture, 1.0 part of a leveling agent (F-556; DIC Co., ltd.) and 6 parts of 2-dimethylamino-2-benzyl-1- (4-morpholinylphenyl) butan-1-one ("Irgacure 369 (Irg 369)", BASF Japan Co., ltd.) as a polymerization initiator were added.

Further, N-methyl-2-pyrrolidone (NMP) was added so that the solid concentration became 13%, and the mixture was stirred at 80℃for 1 hour, whereby a composition for forming a 1 st retardation layer was obtained.

The polymerizable liquid crystal compound a is produced by a method described in japanese patent application laid-open No. 2010-31223. The polymerizable liquid crystal compound B is produced according to the method described in japanese patent application laid-open No. 2009-173893. The respective molecular structures are shown below.

(polymerizable liquid Crystal Compound A)

[ chemical formula 20]

(polymerizable liquid Crystal Compound B)

[ chemical formula 21]

(iii) Preparation of a base material for a retardation layer

A cycloolefin resin film having a thickness of 50 μm (ZF-14-50 manufactured by Japanese ZEON Co., ltd.) was subjected to corona treatment to prepare a retardation layer substrate. Corona treatment was performed using TEC-4AX manufactured by Ushio Motor Co. The corona treatment was carried out 1 time at an output of 0.78kW and a treatment speed of 10 m/min.

(iv) Formation of photo-alignment film

The composition for forming a photo-alignment film is coated on the retardation layer substrate by a bar coater. The coated film was dried at 80℃for 1 minute, and then irradiated with polarized UV light (SPOTCURE SP-7; manufactured by Ushio electric Co., ltd.) at 100mJ/cm ² Is subjected to polarized UV exposure. The thickness of the obtained horizontally oriented film was measured by a laser microscope (LEXT, olympus Co., ltd.), and the result was that100nm.

(v) Formation of the 1 st phase-difference layer

Then, the 1 st retardation layer-forming composition was passed through a PTFE membrane filter (product No. manufactured by ADVANTEC Toyo Co., ltd., product No.; T300A 025A) having a pore diameter of 0.2 μm at room temperature of 25℃under a relative humidity of 30%, and applied onto a base film with an orientation film which was kept at 25℃by using a bar coater. After the coating film was dried at 120℃for 1 minute, ultraviolet light was irradiated (wavelength: 365nm, cumulative light amount at wavelength 365 nm: 1000mJ/cm under nitrogen atmosphere) using a high-pressure mercury lamp (Unicure VB-15201BY-A, manufactured BY Ushio Motor Co., ltd.) ² ). The thickness of the obtained coating film was measured by a laser microscope (LEXT, olympus corporation) and found to be 2 μm.

The retardation value of the 1 st retardation layer thus obtained was measured, and it was Re (450) =121 nm, re (550) =139 nm, and Re (650) =146 nm.

The relationship of the in-plane phase difference values at the respective wavelengths is as follows.

Re(450)/Re(550)＝0.87

Re(650)/Re(550)＝1.05

(7) Production of the 2 nd phase-difference layer

(i) Preparation of oriented Polymer composition (1)

Sulever SE-610 (manufactured by Nissan chemical Co., ltd.) 1 part was mixed with 99 parts of 2-butoxyethanol to obtain an oriented polymer composition (1).

(ii) Preparation of composition for Forming phase-difference layer 2

19.2 parts of polymerizable liquid crystal (LC 242, manufactured by BASF corporation), 0.1 part of leveling agent (BYK-361N, manufactured by BYK Japan corporation), 0.5 part of polymerization initiator (Irgacure 907, manufactured by BASF Japan corporation), 1.1 parts of reaction additive (Laromaer LR-9000, manufactured by BASF Japan corporation) and 79.1 parts of propylene glycol 1-monomethyl ether 2-acetate were mixed. The mixture was stirred at 80℃for 1 hour, whereby a composition for forming a 2 nd retardation layer was obtained.

[ chemical formula 22]

(iii) Preparation of a base material for a retardation layer

(iv) Formation of oriented polymer films

The alignment polymer composition (1) was applied to the retardation layer substrate by using a bar coater, and dried at 90℃for 1 minute to obtain an alignment film. The film thickness of the obtained alignment film was measured by a laser microscope and found to be 34nm.

(v) Formation of the 2 nd phase difference layer

Next, the composition for forming a 2 nd retardation layer was applied onto the alignment film by using a bar coater, dried at 90℃for 1 minute, and irradiated with ultraviolet rays (accumulated light amount at a wavelength of 365 nm: 1000mJ/cm under a nitrogen atmosphere, temperature: 25 ℃) by using a high-pressure mercury lamp ² ) Thus, the 2 nd retardation layer was obtained. The film thickness of the obtained 2 nd retardation layer was measured by a laser microscope, and the film thickness was 450nm. Further, the retardation value at the wavelength of 550nm of the obtained retardation film (2) was measured, and as a result, re (550) =1 nm and rth (550) = -70nm were obtained. That is, the 2 nd retardation layer has optical characteristics represented by the following formula (3). Since the phase difference value at the wavelength of 550nm of COP is approximately 0, the optical characteristics are not affected.

nx≈ny＜nz (3)

(8) Fabrication of phase-difference plate A

Corona treatment is performed on the 1 st retardation layer of the 1 st retardation layer with the retardation layer substrate and the 2 nd retardation layer of the 2 nd retardation layer with the retardation layer substrate, respectively. The 1 st retardation layer of the retardation layer-equipped substrate and the 2 nd retardation layer of the retardation layer-equipped substrate were bonded to each other by applying the prepared active energy ray-curable adhesive a to one corona-treated surface. From the base with phase difference layer The 2 nd retardation layer side of the material is irradiated with ultraviolet light to cure the ultraviolet-curable adhesive, thereby forming an adhesive layer. The UVA with the wavelength of 320nm to 390nm is 420mJ/cm ² Is irradiated with ultraviolet rays. A retardation plate a was obtained in which a retardation layer base material, a 1 st retardation layer, an adhesive layer a, a 2 nd retardation layer, and a retardation layer base material were laminated in this order. The thickness of the cured adhesive layer A was measured by a laser microscope (LEXT, olympic Co., ltd.) and found to be 1.5. Mu.m.

(9) Fabrication of phase-difference plate B

A retardation plate B was produced in the same manner as in (8), except that the active energy ray-curable adhesive B was used instead of the active energy ray-curable adhesive a. A retardation plate B in which a retardation layer base material, a 1 st retardation layer, an adhesive layer B, a 2 nd retardation layer, and a retardation layer base material were laminated in this order was obtained. The thickness of the cured adhesive layer B was measured by a laser microscope (LEXT, olympus corporation) and found to be 3.0 μm.

(10) Fabrication of phase-difference plate C

A retardation plate C was produced in the same manner as the retardation plate B except that the adhesive layer (1) was used instead of the active energy ray-curable adhesive layer B.

(11) Fabrication of phase-difference plate D

A retardation plate D in which a base material, an alignment layer, a 2 nd retardation layer (positive C plate), an alignment layer, and a 1 st retardation layer (λ/4 layer) were laminated in this order was produced as follows.

(substrate)

As a base material, a cycloolefin polymer film (COP) (ZF-14 manufactured by Japanese ZEON Co., ltd.) was prepared.

(Corona treatment)

The corona treatment device used was AGF-B10 manufactured by Chun electric Co., ltd. The corona treatment was performed 1 time under the conditions of an output power of 0.3kW and a treatment speed of 3 m/min using the above corona treatment apparatus.

(high pressure mercury lamp)

As the high-pressure mercury lamp, unicure VB-15201BY-A manufactured BY Ushio electric Co., ltd was used.

The surface of the substrate subjected to corona treatment was coated with the oriented polymer composition (1) prepared in the production of the retardation film a using a bar coater, and dried at 90 ℃ for 1 minute. The film thickness of the obtained alignment film was measured by a laser microscope and found to be 34nm. Next, the composition for forming a 2 nd retardation layer prepared in the production of the retardation film A was applied onto the alignment film using a bar coater, dried at 90℃for 1 minute, and then irradiated with ultraviolet rays (cumulative light amount at a wavelength of 365nm under a nitrogen atmosphere: 1000 mJ/cm) using a high-pressure mercury lamp ² ) Thus, a 2 nd retardation layer (positive C plate) was formed, and a 2 nd retardation film having a 2 nd retardation layer was obtained. The film thickness of the obtained 2 nd retardation layer was measured by a laser microscope, and the film thickness was 450nm. Further, the retardation value at the wavelength of 550nm of the obtained 2 nd retardation film was measured, and as a result, re (550) =1 nm and rth (550) = -70nm. That is, the 2 nd retardation layer has optical characteristics represented by the following formula (3).

nx≈ny＜nz (3)

The phase difference value at the wavelength of 550nm of the substrate was approximately 0, and therefore, the optical characteristics were not affected.

Next, the following alignment polymer composition (2) was applied to the 2 nd retardation layer of the 2 nd retardation film by using a bar coater, and dried at 100 ℃ for 1 minute. The thickness of the obtained alignment film was measured by a laser microscope (LEXT, olympus corporation) and found to be 100nm. Next, the alignment film was subjected to a rubbing treatment, and a 1 st retardation layer-forming composition prepared in the production of the retardation plate a was applied to the treatment surface by a bar coater, and 1 part of Larmer (registered trademark) LR9000 (manufactured by BASF Japan corporation) was further added thereto, followed by drying at 120 ℃ for 1 minute. Ultraviolet rays (cumulative light amount at 365nm in wavelength: 1000mJ/cm under nitrogen atmosphere) were irradiated to the coating film using a high-pressure mercury lamp ² ) Thus, the 1 st retardation layer was formed on the 2 nd retardation layer, and the retardation plate D was obtained. The thickness of the 1 st retardation layer obtained was measured by a laser microscope (LEXT, olympus corporation) and found to be 2 μm. The phase difference value of the obtained phase difference plate D was measuredThe result was Re (450) =121 nm, re (550) =139 nm, re (650) =146 nm.

Re(450)/Re(550)＝0.87

Re(650)/Re(550)＝1.05

That is, the obtained retardation plate D has the optical characteristics shown in the above-mentioned formulas (1), (2) and (4).

(oriented Polymer composition (2))

A commercially available polyvinyl alcohol (polyvinyl alcohol 1000, manufactured by Wako pure chemical industries, ltd.) and water were added, and the mixture was heated at 100℃for 1 hour to obtain an oriented polymer composition (2) having a solid content of 2% by mass (solvent concentration 98% by mass).

(12) Manufacture of circular polarizing plate

Example 1

The polarizing plate of the linear polarizing plate is subjected to corona treatment, and after one release film is peeled off from the adhesive layer (1) with the release film, the other release film of the adhesive layer is peeled off. The phase difference layer base material on the 1 st phase difference layer side of the phase difference plate A is peeled off from the adhesive layer and subjected to corona treatment. Then, the surface of the retardation layer base material from which the 2 nd retardation layer was peeled was subjected to corona treatment, and the surface from which one of the release films of the pressure-sensitive adhesive layer (2) with a release film was peeled was bonded. Thus, a circularly polarizing plate of example 1 was obtained in which a linear polarizing plate/adhesive layer (1)/1 st retardation layer/adhesive layer a/2 nd retardation layer/adhesive layer (2)/release film were laminated.

Example 2

A circularly polarizing plate was produced in the same manner as in example 1, except that the adhesive layer (2) was used instead of the adhesive layer (1).

Example 3

A circularly polarizing plate was produced in the same manner as in example 1, except that the adhesive layer (3) was used instead of the adhesive layer (1).

Example 4

The retardation was peeled off from the polarizing plate side of the linear polarizing plate and the 1 st retardation layer side of the retardation plate aThe surfaces of the layer substrates were each subjected to corona treatment. The active energy ray-curable adhesive C prepared by coating one corona-treated surface was bonded to the retardation plate a. The ultraviolet-curable adhesive is cured by irradiation of ultraviolet rays from the linear polarizing plate side, thereby forming an adhesive layer C. The ultraviolet light is 420mJ/cm ² To irradiate UVA with a wavelength of 320nm to 390 nm. The thickness of the cured active energy ray-curable adhesive was measured by a laser microscope (LEXT, olympic Co., ltd.) and found to be 1.5. Mu.m. Then, the surface of the retardation layer substrate from which the 2 nd retardation layer was peeled was subjected to corona treatment, and the surface of the pressure-sensitive adhesive layer (2) with a release film from which one release film was peeled was bonded. Thus, a circular polarizing plate of comparative example 1 in which a linear polarizing plate/an adhesive layer C/a 1 st retardation layer/an adhesive layer a/a 2 nd retardation layer/an adhesive layer (2)/a release film were laminated was obtained.

Example 5

A circularly polarizing plate was produced in the same manner as in example 1, except that the phase difference plate D was used instead of the phase difference plate a. After the base material used for forming the phase difference layer is peeled off, the pressure-sensitive adhesive layer (2) is laminated.

Example 6

A circularly polarizing plate was produced in the same manner as in example 5, except that the adhesive layer (2) was used instead of the adhesive layer (1).

Example 7

A circularly polarizing plate was produced in the same manner as in example 5, except that the adhesive layer (3) was used instead of the adhesive layer (1).

Example 8

A circularly polarizing plate was produced in the same manner as in example 4, except that the phase difference plate D was used instead of the phase difference plate a.

Comparative example 1

A circularly polarizing plate was produced in the same manner as in example 4, except that the active energy ray-curable adhesive B was used instead of the active energy ray-curable adhesive C.

Comparative example 2

A circularly polarizing plate was produced in the same manner as in comparative example 1, except that the phase difference plate D was used instead of the phase difference plate a.

Reference example 1

A circularly polarizing plate was produced in the same manner as in comparative example 1, except that the phase difference plate C was used instead of the phase difference plate a.

Reference example 2

A circularly polarizing plate was produced in the same manner as in comparative example 1, except that the phase difference plate B was used instead of the phase difference plate a.

(13) Evaluation of adhesion

The adhesion between the 1 st retardation layer and the 2 nd retardation layer of the obtained circularly polarizing plate was evaluated by the following method.

(i) Preparation of sample for evaluating adhesion between phase-difference layers

A cycloolefin resin film having a thickness of 50 μm (ZF-14-50 manufactured by Japanese ZEON Co., ltd.) was subjected to corona treatment, and the surface of the release film formed in (12) from which each circular polarizing plate was released was bonded. Next, corona treatment was performed on the linear polarizing plate side surface of the circular polarizing plate, and the surface of the adhesive layer (2) with a release film from which one release film was peeled was attached, and this was used as a sample for evaluating adhesion between retardation layers.

(ii) Adhesion evaluation 1 (initial)

The obtained sample for evaluating adhesion was cut into dimensions of 200mm in length by 25mm in width, and the cut sample was bonded to an alkali-free glass plate via an adhesive layer on the side of a linear polarizing plate. It was left for 1 day at a temperature of 23℃under an atmosphere of 60% relative humidity.

A peeling test was performed in which the sample for evaluation bonded to the alkali-free glass plate was peeled off between the 1 st retardation layer and the 2 nd retardation layer in the 180 ° direction at a peeling speed of 300 mm/min. The peel strength (adhesion) [ N/25mm ] at this time was measured using "Autograph AGS-50NX" manufactured by Shimadzu corporation. The measurement results are shown in Table 1. In reference examples 1 and 2, the 1 st retardation layer and the 2 nd retardation layer were in close contact to an undetectable extent. In reference examples 1 and 2, it can be said that the peel strength between the 1 st retardation layer and the 2 nd retardation layer exceeds 1.0N/25mm.

(iii) Adhesion evaluation 2 (after high humidity and heat test)

After a high humidity and heat test at a temperature of 80℃and a relative humidity of 90% RH for 48 hours was performed on a sample for evaluation bonded to an alkali-free glass plate, adhesion between the 1 st retardation layer and the 2 nd retardation layer was evaluated by the same method as in (ii). The measurement results are shown in Table 1. In reference examples 1 and 2, the 1 st retardation layer and the 2 nd retardation layer were in close contact to an undetectable extent. In reference examples 1 and 2, it can be said that the peel strength between the 1 st retardation layer and the 2 nd retardation layer exceeds 1.0N/25mm.

(14) Durability evaluation

The durability of the obtained circularly polarizing plate against external force was evaluated by the following method.

(i) Durability evaluation 1 (initial)

The obtained circularly polarizing plate was evaluated by a cross-hatch test (a "cross-hatch adhesion test" in JIS) according to JIS D0202-1988 as an index of durability against external force. The release film on the 2 nd retardation layer side of the circularly polarizing plate is peeled off and bonded to glass via an adhesive layer (2). On the side of the linear polarizing plate opposite to the glass surface, 100 1mm square checkerboards were cut with a cutter, and the adhesive tape (25 mm wide, manufactured by Nichiban) was completely attached. Next, the adhesive tape was peeled off in a direction of 90 ° with respect to the face. The durability against external force was evaluated in terms of the number of remaining checkerboards without peeling among 100 checkerboards. The number of the remaining checkerboards is 95 to 100/100, which is denoted as A, 50 to 95/100, which is denoted as B, and 0 to 49/100, which is denoted as C. The evaluation results are shown in table 1.

(ii) Durability evaluation 2 (after high humidity and heat test)

The obtained polarizing plate was subjected to a high humidity heat test at a temperature of 80 ° and a relative humidity of 90% rh for 48 hours, and then the durability against external force was evaluated by the same method as in (i). The evaluation results are shown in table 1.

TABLE 1

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Claims

1. A polarizing plate comprising a linear polarizing plate, a 1 st lamination layer and a phase difference plate laminated in this order,

the 1 st phase difference layer and the 2 nd phase difference layer comprise cured products of liquid crystal compounds,

the peel strength between the 1 st phase difference layer and the 2 nd phase difference layer is 1.0N/25mm or less,

the 1 st bonding layer contains an adhesive agent having a tensile storage modulus of 10MPa or less at a temperature of 23 ℃.

2. The polarizing plate according to claim 1, wherein the retardation plate has only an alignment film or no other layer interposed between the 1 st retardation layer and the 2 nd retardation layer.

3. The polarizing plate according to claim 1 or 2, wherein the linear polarizing plate has a polarizing plate,

the thickness of the polarizer is 15 μm or less.

4. The polarizing plate according to claim 3, wherein the linear polarizing plate has a protective film provided on a surface of the polarizing plate opposite to the 1 st lamination layer,

The thickness of the protective film is 30 μm or less.

5. The polarizing plate according to claim 1 or 2, wherein the 1 st retardation layer is an inversely dispersible λ/4 layer.

6. The polarizing plate according to claim 1 or 2, wherein the 2 nd retardation layer is a positive C plate.