Detailed Description
Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.
A. Substrate with transparent electrode layer
The substrate with a transparent electrode layer has: a light-transmitting substrate; a transparent electrode layer disposed on one side of the light-transmissive substrate; and a hard coat layer (1 st hard coat layer) provided on the other side of the light-transmitting substrate and including a cured resin film and particles dispersed in the cured resin film. An alignment film may be provided on the surface of the transparent electrode layer according to a driving mode. The substrate with a transparent electrode layer may further contain any appropriate constituent element as necessary. Examples of the optional constituent elements include a refractive index adjustment layer and a 2 nd hard coat layer.
The thickness of the substrate with a transparent electrode layer is, for example, 10 to 100. mu.m, preferably 15 to 80 μm, more preferably 15 to 70 μm, and still more preferably 20 to 60 μm.
The surface resistance value of the substrate with the transparent electrode layer is preferably 0.1. omega./□ to 1000. omega./□, more preferably 0.5. omega./□ to 600. omega./□, and further preferably 1. omega./□ to 400. omega./□.
The haze value (%) of the substrate with the transparent electrode layer is preferably 2.0 or more, more preferably 2.0 to 15, even more preferably 5.0 to 12, and even more preferably 8.0 to 10. If the haze value is less than 2.0, the effect of suppressing Newton's rings may not be sufficiently obtained. On the other hand, if the haze value is too high, the viewing angle in the narrow viewing angle mode may not be sufficiently narrowed when the light control film described in item B is incorporated into a liquid crystal display device.
The total light transmittance of the substrate with the transparent electrode layer is preferably 50% or more, and more preferably 80% to 99%.
A-1. integral construction of substrate with transparent electrode layer
Fig. 1 (a) to (c) are schematic cross-sectional views of the substrate with a transparent electrode layer according to 1 embodiment of the present invention. The substrate 100a with a transparent electrode layer shown in fig. 1 (a) includes: a light-transmitting substrate 10; a transparent electrode layer 20 provided on one side of the light-transmitting substrate 10; and a 1 st hard coat layer 30 provided on the other side of the light-transmissive substrate 10.
The substrate 100b with a transparent electrode layer shown in fig. 1 (b) differs from the substrate 100a with a transparent electrode layer in the following respects: a refractive index adjustment layer 40 is further provided between the light-transmitting substrate 10 and the transparent electrode layer 20. In addition, the substrate 100c with a transparent electrode layer shown in fig. 1 (c) is different from the substrate 100b with a transparent electrode layer in the following respects: a 2 nd hard coat layer 50 is further provided between the light-transmissive substrate 10 and the refractive index adjustment layer 40. Although not shown, the substrate with the transparent electrode layer may be configured as follows: the refractive index adjustment layer is not provided between the light-transmitting substrate and the transparent electrode layer, and only the 2 nd hard coat layer is provided.
Hereinafter, each constituent element of the substrate with the transparent electrode layer will be described.
A-2. light-transmitting base Material
The light-transmitting substrate is typically a polymer film containing a thermoplastic resin as a main component. As the thermoplastic resin, any suitable thermoplastic resin can be used. From the viewpoint of obtaining a desired front retardation described later, a cycloolefin resin such as a polynorbornene resin, a polycarbonate resin, an acrylic resin, and the like can be preferably used, and among them, a cycloolefin resin can be preferably used.
The polynorbornene resin is a (co) polymer obtained by using a norbornene monomer having a norbornene ring as a part or all of the starting materials (monomers). Examples of the norbornene-based monomer include: norbornene, and alkyl and/or alkylidene substituents thereof, for example, polar group substituents such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene and the like, halogen and the like; dicyclopentadiene, 2, 3-dihydrodicyclopentadiene, and the like; dimethyloctahydronaphthalene, alkyl and/or alkylidene substituents thereof, and polar group substituents such as halogen, for example, 6-methyl-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-ethyl-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-ethylidene-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-chloro-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-cyano-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-pyridyl-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, 6-methoxycarbonyl-1, 4: 5, 8-dimethylbridge-1, 4,4a,5,6,7,8,8 a-octahydronaphthalene, etc.; 3-4 mer of cyclopentadiene, for example, 4, 9: 5, 8-dimethylbridge-3 a,4,4a,5,8,8a,9,9 a-octahydro-1H-benzindene, 4, 11: 5,10: 6, 9-trimethyl-bridge-3 a,4,4a,5,5a,6,9,9a,10,10a,11,11 a-dodecahydro-1H-cyclopenta-anthracene, and the like.
Various products are commercially available as the polynorbornene resin. Specific examples thereof include trade names "Zeonex" and "Zeonor" manufactured by zeon corporation, trade name "Arton" manufactured by JSR corporation, trade name "Topas" manufactured by TICONA corporation, and trade name "APEL" manufactured by mitsui chemical corporation.
The front retardation of the light-transmitting substrate at a wavelength of 590nm is preferably 50nm or less, more preferably 0nm to 30nm, and still more preferably 0nm to 10 nm. When the front phase difference value is within the above range, a narrower viewing angle display can be realized when the light control film described in item B is used as a viewing angle display unit of a liquid crystal display device capable of switching between a wide viewing angle and a narrow viewing angle. In the present specification, the front phase difference (R)0) The following values are given: when nx is a refractive index in a direction in which an in-plane refractive index is maximized (i.e., a slow axis direction), ny is a refractive index in a direction orthogonal to the slow axis (i.e., a fast axis direction) in a plane, and d (nm) is a thickness of the thin film at 23 ℃, the R passes0The term "value obtained by (nx-ny) × d" means a value at a wavelength of 590nm unless otherwise specified.
The thickness of the light-transmitting substrate is, for example, 70 μm or less, preferably 10 to 70 μm, more preferably 15 to 65 μm, and still more preferably 20 to 60 μm. By providing the light-transmitting substrate with a thickness in this range, the light-transmitting substrate functions as a support substrate for the light control film, and can contribute to the reduction in thickness of the light control film and the liquid crystal display device.
A-3. transparent electrode layer
As the transparent electrode layer, Indium Tin Oxide (ITO), zinc oxide (ZnO), or tin oxide (SnO) can be used, for example2) And the like. In the above case, the metal oxide may be an amorphous metal oxide or a crystalline metal oxide. Alternatively, the transparent electrode layer may be made of metal nanowires such as silver nanowires (AgNW) or Carbon Nanotubes (CNT)) An organic conductive film, a metal layer, or a laminate thereof. The transparent electrode layer may be patterned into a desired shape according to the purpose.
The thickness of the transparent electrode layer is, for example, 0.01 to 0.10. mu.m, preferably 0.01 to 0.045. mu.m.
The transparent electrode layer can be formed on one side of the light-transmitting substrate by sputtering, for example.
A-4. 1 st hard coat layer
Fig. 2 is a schematic view illustrating the structure of the 1 st hard coat layer in 1 embodiment of the present invention. The 1 st hard coat layer 30 includes a cured resin film 32 provided on one surface of the light-transmissive substrate, and particles 34 dispersed in the cured resin film 32.
On the surface of the 1 st hard coating, the coating is present at 1mm2The number of particles per unit area (for example, a square of 1mm × 1 mm) of (a) is 1500 or more, preferably 2000 or more, more preferably 2500 or more, further preferably 3000 to 5000, and further more preferably 3500 to 4500. By dispersing the particles at such a density, light can be diffused appropriately and uniformly, and as a result, generation of newton rings can be suppressed appropriately.
In 1 preferred embodiment, when the diameter of the particle 34 is X μm and the thickness of the cured resin film 32 is Y μm, X and Y satisfy the relationship of X-Y > 0.6. When the light control film described in item B is incorporated into a liquid crystal display device by satisfying the relationship of X-Y >0.6, it is possible to sufficiently secure the distance between the light control film and an adjacent component (for example, a liquid crystal panel), and to provide appropriate irregularities to the 1 st hard coat layer surface (as a result, the substrate surface with a transparent electrode layer or the light control film surface), to scatter light, and to suppress the occurrence of newton rings. On the other hand, if the value of X-Y is too large, the risk of particle shedding may increase. X-Y is preferably 0.8 or more, more preferably 0.9 or more, and still more preferably satisfies the relationship of 1.0. ltoreq. X-Y. ltoreq.1.3.
The cured resin film can be formed by curing a resin composition containing a curable resin such as a thermosetting resin, a thermoplastic resin, an ultraviolet curable resin, an electron beam curable resin, or a two-component hybrid resin. Among these, an ultraviolet-curable resin composition which can be cured efficiently and easily by curing treatment by ultraviolet irradiation is suitable. The resin composition preferably further contains a polymerization initiator (typically, a photopolymerization initiator), and may contain any appropriate additive such as a plasticizer, a surfactant, an antioxidant, an ultraviolet absorber, a leveling agent, a thixotropic agent, and an antistatic agent, if necessary.
Examples of the ultraviolet curable resin include various resins such as polyester resins, acrylic resins, urethane resins, amide resins, silicone resins, and epoxy resins. The ultraviolet curable resin includes ultraviolet curable monomers, oligomers, and polymers. Typical examples of the ultraviolet curable resin include: a polymer obtained by addition reaction of acrylic acid and a glycidyl acrylate polymer, or a polymer obtained by using a polyfunctional acrylate (pentaerythritol, dipentaerythritol, etc.). In addition, urethane (meth) acrylates can also be preferably used.
In 1 embodiment, the cured resin film is a resin film obtained by curing a resin composition containing a high-molecular-weight component having a weight-average molecular weight of 10000 or more and a low-molecular-weight component having a weight-average molecular weight of less than 10000. In such a cured resin film, the structure derived from a high molecular weight component having a weight average molecular weight of 10000 or more functions as a soft segment, and the structure derived from a low molecular weight component having a weight average molecular weight of less than 10000 functions as a hard segment, so that the substrate for the transparent electrode layer can be provided with scratch resistance and also can be provided with fracture resistance at the time of bending.
In the resin composition, the amount of the high molecular weight component is preferably 90% by weight or less, and more preferably 85% by weight or less, based on the total amount of the high molecular weight component and the low molecular weight component. On the other hand, the lower limit of the amount of the high molecular weight component is preferably 80% by weight or more. By setting the amount of the high molecular weight component in the resin composition for forming a cured resin film within the above range, appropriate flexibility can be imparted to the cured resin film.
For details of the resin film obtained by curing the resin composition containing the high-molecular weight component having a weight average molecular weight of 10000 or more and the low-molecular weight component having a weight average molecular weight of less than 10000, refer to the description of japanese patent application laid-open No. 2015-115171. The entire disclosure of this publication is incorporated herein by reference.
As the particles, those having transparency such as various metal oxides, glass, and plastics can be used. Examples thereof include: inorganic particles such as silica, alumina, titania, zirconia, and calcium oxide, crosslinked or uncrosslinked organic particles including various polymers such as polymethyl methacrylate, polystyrene, polyurethane, acrylic resin, acrylic-styrene copolymer, benzoguanamine, melamine, and polycarbonate, and silicone particles. Among them, organic particles are preferably used, and acrylic resins are more preferred from the viewpoint of refractive index. The number of the particles may be 1 or 2 or more.
The thickness (Y) of the cured resin film is preferably 0.4 to 2.0. mu.m, more preferably 0.5 to 1.5. mu.m. On the other hand, the diameter (X) of the particles is preferably such that X-Y satisfies the above-mentioned predetermined relationship (i.e., the relationship of X-Y > 0.6), and may be, for example, 1.0 to 3.0. mu.m, preferably 1.2 to 2.5. mu.m. In 1 embodiment, the diameter of the particles may be 150% or more and 500% or less, preferably 160% to 400%, more preferably 180% to 350% of the thickness of the cured resin film. In the present specification, the diameter (X) of the particles is a mode particle diameter indicating a maximum value of a particle distribution, and is obtained by measuring the particle diameter under a predetermined condition (shear liquid: ethyl acetate, measurement mode: HPF measurement, measurement mode: total count) with a flow type particle image analyzer (product name "FPTA-3000S" manufactured by Sysmex corporation). For the measurement sample, the particles were diluted with ethyl acetate to 1.0 wt%, and uniformly dispersed with an ultrasonic cleaner.
The 1 st hard coat layer may be formed as follows: the resin composition and the particles for forming the cured resin film are mixed with a solvent, an additive, a catalyst, and the like as needed to prepare a coating liquid, and the coating liquid is applied to one surface of the light-transmitting substrate and dried to cure the coating film. In the coating liquid, the particles are preferably dispersed in a solution. As a method of dispersing the particles in the coating liquid, the following method can be employed: a method of adding and mixing particles to a resin composition solution; a method of adding particles dispersed in a solvent in advance to a resin composition solution, and the like.
The solid content concentration of the coating liquid is preferably 1 to 70% by weight, more preferably 2 to 50% by weight, and still more preferably 5 to 40% by weight.
Examples of the coating method of the coating liquid include a dip coating method, an air knife coating method, a curtain coating method, a roll coating method, a wire bar coating method, a gravure coating method, a die coating method, an extrusion coating method, and the like.
The curing of the coating film may be appropriately selected depending on the kind of the resin composition and the like. When the resin composition is photocurable, it can be cured by irradiating it with light from a light source that emits light of a desired wavelength. As the light to be irradiated, for example, an exposure amount of 150mJ/cm can be used2Light of above, preferably 200mJ/cm2~1000mJ/cm2Of (2) is detected. Further, for example, irradiation light having a wavelength of 380nm or less may be used. Heating may be performed during the photocuring treatment.
A-5 refractive index adjusting layer
The refractive index adjustment layer can suppress interface reflection between the light-transmissive substrate and the transparent electrode layer. Accordingly, when the light control film described in item B is incorporated as a viewing angle display unit in a liquid crystal display device, reflection scattering on the opposite light source device side is reduced, and as a result, improvement of light transmittance can be facilitated. The refractive index adjustment layer may be a single layer or a laminate of 2 or more layers.
The refractive index of the refractive index adjustment layer is preferably 1.3 to 1.8, more preferably 1.35 to 1.7, and further preferably 1.40 to 1.65. This can suitably reduce the interface reflection between the light-transmissive substrate and the transparent electrode layer.
The refractive index adjusting layer may beFormed of inorganic substances, organic substances, or a mixture of inorganic substances and organic substances. Examples of the material for forming the refractive index adjusting layer include NaF and Na3AlF6、LiF、MgF2、CaF2、SiO2、LaF3、CeF3、Al2O3、TiO2、Ta2O5、ZrO2、ZnO、ZnS、SiOxInorganic substances (x is 1.5 or more and less than 2), and organic substances such as acrylic resins, epoxy resins, urethane resins, melamine resins, alkyd resins, and siloxane polymers. As the organic substance, a thermosetting resin formed of a mixture of a melamine resin, an alkyd resin, and an organosilane condensate is particularly preferably used.
The refractive index adjustment layer may contain nanoparticles having an average particle diameter of 1nm to 100 nm. The refractive index adjusting layer contains nanoparticles, so that the refractive index of the refractive index adjusting layer itself can be easily adjusted.
The content of the nanoparticles in the refractive index adjustment layer is preferably 0.1 to 90% by weight. The content of the nanoparticles in the refractive index adjustment layer is more preferably 10 to 80 wt%, and still more preferably 20 to 70 wt%.
Examples of the inorganic oxide forming the nanoparticles include silicon oxide (silica), hollow nano-silica, titanium oxide, alumina, zinc oxide, tin oxide, zirconium oxide, niobium oxide, and the like. Among them, silicon oxide (silica), titanium oxide, alumina, zinc oxide, tin oxide, zirconium oxide, and niobium oxide are preferable. These can be used alone in 1 kind, also can be combined with more than 2 kinds.
The thickness of the refractive index adjustment layer is preferably 10nm to 200nm, more preferably 20nm to 150nm, and still more preferably 30nm to 130 nm. If the thickness of the refractive index adjustment layer is too small, the layer is not easily a continuous film. If the thickness of the refractive index adjustment layer is too large, the transparency of the light control film in a light transmissive state tends to be lowered, or cracks tend to be easily generated.
The refractive index adjusting layer can be formed by a coating method such as a wet method, a gravure coating method, or a bar coating method, a vacuum deposition method, a sputtering method, or an ion plating method using the above-mentioned materials.
A-6. 2 nd hard coat layer
The 2 nd hard coat layer is a curable resin film obtained by curing a resin composition containing a curable resin, and typically contains no particles. According to the 2 nd hard coat layer containing no particles, since impact resistance and scratch resistance are imparted to the light-transmitting substrate, and a smooth surface is further provided, a refractive index adjusting layer and/or a transparent electrode layer can be formed thereon with excellent adhesion.
As the resin composition for forming the cured resin film, the same description as that of the cured resin film constituting the 1 st hard coat layer can be applied. The composition of the resin of the cured resin film constituting the 1 st hard coat layer and the composition of the resin of the cured resin film constituting the 2 nd hard coat layer may be the same or different.
The thickness of the 2 nd hard coat layer may be preferably 0.5 to 2.0. mu.m, more preferably 0.8 to 1.5. mu.m.
The same description as that of the formation method of the 1 st hard coat layer can be applied to the formation method of the 2 nd hard coat layer.
B. Light modulation film
According to another aspect of the present invention, there is provided a light modulation film having: a substrate with a 1 st transparent electrode layer and a substrate with a 2 nd transparent electrode layer, which are arranged such that the transparent electrode layers face each other; and a liquid crystal light adjusting layer sandwiched between the substrates with the transparent electrode layers. In the light control film, either or both of the substrate with the transparent electrode layer 1 and the substrate with the transparent electrode layer 2 is the substrate with the transparent electrode layer described in item a.
As described later, the light control film can change the scattering state (as a result, haze) of transmitted light according to voltage application to the liquid crystal light control layer. Thus, when incorporated in a liquid crystal display device, the light control film is set to a low haze state (light transmission state), whereby light incident from the back surface side can be directly transmitted, and narrow viewing angle display can be suitably realized. Further, by forming a high haze state (light scattering state), light incident from the back surface side is scattered, and wide viewing angle display can be suitably realized.
The entire thickness of the light control film is, for example, 20 to 200. mu.m, preferably 30 to 180 μm, and more preferably 40 to 150. mu.m.
B-1 integral constitution of light-adjusting film
Fig. 3 (a) is a schematic cross-sectional view of a dimming film according to 1 embodiment of the present invention. The light control film 200a includes: a 1 st substrate 100d with a transparent electrode layer and a 2 nd substrate 100e with a transparent electrode layer; and a liquid crystal light modulation layer 120 sandwiched between the substrates 100d and 100e with transparent electrode layers. In the illustrated example, the substrate 100d with a transparent electrode layer 1 and the substrate 100e with a transparent electrode layer 2 are substrates with a transparent electrode layer described in item a, respectively, and include: a light-transmitting substrate 10; a transparent electrode layer 20 provided on one side (the liquid crystal light modulation layer 120 side) of the light-transmitting substrate 10; and a 1 st hard coat layer 30 provided on the other side of the light-transmissive substrate 10.
Fig. 3 (b) is a schematic cross-sectional view of a dimming film according to another embodiment of the present invention. The light control film 200b includes: a 1 st substrate 100f with a transparent electrode layer and a 2 nd substrate 100g with a transparent electrode layer; and a liquid crystal light adjusting layer 120 sandwiched between the substrates 100f and 100g with transparent electrode layers. In the illustrated example, the substrate 100f with a transparent electrode layer of item 1 is the substrate with a transparent electrode layer described in item a, and includes: a light-transmitting substrate 10; a transparent electrode layer 20 provided on one side (the liquid crystal light modulation layer 120 side) of the light-transmitting substrate 10; and a 1 st hard coat layer 30 provided on the other side of the light-transmissive substrate 10. On the other hand, the substrate 100g with the transparent electrode layer of the 2 nd band includes the light transmissive substrate 10 and the transparent electrode layer 20 provided on one side (the liquid crystal light modulation layer 120 side) of the light transmissive substrate 10, but does not include the hard coat layer 30 of the 1 st band.
B-2. base material with transparent electrode layer
At least one of the substrate with a transparent electrode layer 1 and the substrate with a transparent electrode layer 2 is the substrate with a transparent electrode layer described in item A. Preferably, both the substrate with the transparent electrode layer 1 and the substrate with the transparent electrode layer 2 are the substrates with the transparent electrode layer described in item a. The substrate with the 1 st transparent electrode layer and the substrate with the 2 nd transparent electrode layer may have the same configuration or different configurations.
When a substrate with a transparent electrode layer other than the substrate with a transparent electrode layer described in item a is used as either one of the substrate with a transparent electrode layer 1 and the substrate with a transparent electrode layer 2, any appropriate conductive substrate having a light-transmitting substrate and a transparent electrode layer provided on one side of the light-transmitting substrate can be used as the substrate with a transparent electrode layer other than the substrate with a transparent electrode layer described in item a, and the same description as that of the substrate with a transparent electrode layer described in item a can be applied except that the 1 st hard coat layer is not provided.
B-3. liquid crystal dimming layer
The liquid crystal light modulation layer typically has a structure in which a liquid crystal compound is dispersed in a resin matrix. Specific examples thereof include a light control layer containing a polymer dispersed liquid crystal, a light control layer containing a polymer network liquid crystal, and the like. The polymer dispersed liquid crystal has a structure in which liquid crystals are separated in a polymer internal phase. The polymer network type liquid crystal has a structure in which liquid crystal is dispersed in a polymer network, and the liquid crystal in the polymer network has a continuous phase. In the liquid crystal light modulation layer, the scattering state of the transmitted light is changed by a change in the degree of alignment of the liquid crystal compound according to the amount of applied voltage, whereby the light transmission state and the light scattering state can be switched.
In 1 embodiment, the liquid crystal light modulation layer is in a light transmitting state by applying a voltage, and is in a light scattering state (normal mode) in a state where no voltage is applied. In this embodiment, the liquid crystal compound is not aligned when no voltage is applied, and therefore, the liquid crystal compound is in a light scattering state, and the liquid crystal compound is aligned by applying a voltage, so that the refractive index of the liquid crystal compound matches the refractive index of the resin matrix, and as a result, the liquid crystal compound is in a light transmitting state.
In another embodiment, the liquid crystal light modulation layer is in a light scattering state by applying a voltage, and is in a light transmitting state (reverse mode) in a state where no voltage is applied. In this embodiment, the alignment film provided on the surface of the transparent electrode layer aligns the liquid crystal compound to be in a light-transmitting state when no voltage is applied, and aligns the liquid crystal compound to be in a light-scattering state when a voltage is applied.
As the liquid crystal compound, any appropriate non-polymerizable liquid crystal compound can be used. Examples thereof include nematic, smectic (semiconducting) and cholesteric (cholesteric) liquid crystal compounds. From the viewpoint of achieving excellent transparency in the transmissive mode, a nematic liquid crystal compound is preferably used. Examples of the nematic liquid crystal compound include biphenyl compounds, benzoate compounds, cyclohexylbenzene compounds, azoxybenzene compounds, azomethine compounds, terphenyl compounds, biphenyl benzoate compounds, cyclohexylbiphenyl compounds, phenylpyridine compounds, cyclohexylpyrimidine compounds, cholesterol compounds, and the like.
The content ratio of the liquid crystal compound in the liquid crystal light modulation layer is, for example, 10% by weight or more, preferably 30% by weight or more, more preferably 35% by weight or more, and further preferably 40% by weight or more. The content ratio is, for example, 90% by weight or less, preferably 70% by weight or less.
The resin forming the resin matrix may be appropriately selected depending on the light transmittance, the refractive index of the liquid crystal compound, and the like. Examples thereof include water-soluble resins or water-dispersible resins such as urethane resins, polyvinyl alcohol resins, polyethylene resins, polypropylene resins, and acrylic resins, and radiation-curable resins such as liquid crystal polymers, (meth) acrylic resins, silicone resins, epoxy resins, fluorine resins, polyester resins, and polyimide resins.
The content ratio of the matrix resin in the liquid crystal light modulation layer is, for example, 90 wt% or less, preferably 70 wt% or less, more preferably 65 wt% or less, and further preferably 60 wt% or less. The content ratio is, for example, 10% by weight or more, preferably 30% by weight or more.
The thickness of the liquid crystal light modulation layer is preferably 2 μm to 30 μm, more preferably 3 μm to 20 μm, and further preferably 5 μm to 15 μm.
The liquid crystal dimming layer can be made by any suitable method. Specific examples thereof include production methods by an emulsion method and a phase separation method.
The method for producing the emulsion type liquid crystal light-adjusting layer includes, for example, the steps of: coating an emulsion coating liquid containing a matrix-forming resin and a liquid crystal compound on a transparent electrode layer side of a substrate having a transparent electrode layer to form a coating layer; and drying the coating layer to form the matrix-forming resin into a resin matrix. The emulsion coating liquid is preferably an emulsion as follows: the continuous phase contains a mixed solution of a matrix-forming resin and a coating solvent, and the dispersed phase contains a liquid crystal compound. By coating and drying the emulsified coating liquid, a liquid crystal dimming layer having a configuration in which a liquid crystal compound is dispersed in a resin matrix can be formed. Typically, another substrate having a transparent electrode layer is laminated on the liquid crystal light modulation layer, thereby obtaining a light modulation film.
The method for manufacturing the phase separation type liquid crystal dimming layer includes, for example, the steps of: coating a coating liquid containing a radiation-curable matrix-forming resin and a liquid crystal compound on a transparent electrode layer side of a substrate having a transparent electrode layer to form a coating layer; laminating another substrate with a transparent electrode layer on the coating layer to form a laminated body; and irradiating the laminate with radiation to polymerize the matrix-forming resin, thereby causing phase separation between the resin matrix and the liquid crystal compound. The coating liquid is preferably in a homogeneous phase state. Alternatively, a coating liquid may be filled between the 1 st base material with the transparent electrode layer and the 2 nd base material with the transparent electrode layer, which are stacked with a spacer, and then phase separation by irradiation of radiation may be performed.
C. Liquid crystal display device having a plurality of pixel electrodes
According to still another aspect of the present invention, there is provided a liquid crystal display device. The liquid crystal display device includes, in order from a viewing side: a liquid crystal panel; a light modulating film; and a surface light source device, the liquid crystal panel including: the liquid crystal display device includes a liquid crystal cell, a viewing-side polarizing plate disposed on a viewing side of the liquid crystal cell, and a back-side polarizing plate disposed on an opposite side to the viewing side of the liquid crystal cell. According to the liquid crystal display device having such a configuration, the light control film can directly transmit the light emitted from the surface light source device through the light control film in the light transmissive state, and as a result, display with a narrow viewing angle can be suitably realized. Further, by making the light control film in a light scattering state, light emitted from the surface light source device is scattered, and switching to wide-angle display is possible.
C-1. integral constitution of liquid crystal display device
Fig. 4 is a diagram illustrating a liquid crystal display device 300 according to 1 embodiment of the present invention. The liquid crystal display device 300 of the present embodiment includes, in order from the visible side: a liquid crystal panel 310; a light adjusting film 200; and a surface light source device 320 for emitting light to the light control film 200, wherein the liquid crystal panel 310 includes: a liquid crystal cell 312, a viewing-side polarizing plate 314 disposed on the viewing side of the liquid crystal cell 312, and a back-side polarizing plate 316 disposed on the opposite side of the viewing side of the liquid crystal cell 312.
In the liquid crystal display device 300, the optical members adjacent to each other are preferably arranged adjacent to or in contact with each other without being bonded to each other via an adhesive layer such as an adhesive layer or an adhesive layer. In the prior art, when adjacent optical members are disposed adjacent to or in contact with each other without an adhesive layer, newton rings are easily generated, and the effects of the present invention can be suitably obtained by the present invention.
C-2 liquid crystal panel
The liquid crystal panel 310 typically includes: a liquid crystal cell 312, a viewing-side polarizing plate 314 disposed on the viewing side of the liquid crystal cell, and a back-side polarizing plate 316 disposed on the opposite side (back side) to the viewing side of the liquid crystal cell. Although not shown, a reflective polarizer may be further provided on the back surface side of the back-surface-side polarizing plate 316 via an adhesive layer or an adhesive layer with light diffusion. The visible-side polarizing plate 314 and the back-side polarizing plate 316 may be arranged such that their absorption axes are substantially orthogonal or parallel to each other.
The liquid crystal cell has: a pair of substrates, and a liquid crystal layer as a display medium sandwiched between the substrates. In a general configuration, a color filter and a black matrix are provided on one substrate, and: a switching element for controlling electro-optical characteristics of the liquid crystal, a scanning line for supplying a gate signal to the switching element, a signal line for supplying a source signal to the switching element, and a pixel electrode and a counter electrode. The spacing (cell gap) between the substrates can be controlled by spacers or the like. An alignment film made of, for example, polyimide may be provided on the side of the substrate in contact with the liquid crystal layer.
In one embodiment, the liquid crystal layer includes: liquid crystal molecules aligned in parallel in the absence of an electric field. Such a liquid crystal layer (as a result, a liquid crystal cell) representatively shows a three-dimensional refractive index nx > ny ═ nz. In the present specification, ny ═ nz means not only that ny is completely the same as nz, but also that ny is substantially the same as nz. Typical examples of a driving mode using a liquid crystal layer having such a three-dimensional refractive index include an in-plane switching (IPS) mode, a Fringe Field Switching (FFS) mode, and the like. The IPS mode includes: a super/in-plane switching (S-IPS) mode and an advanced/super/in-plane switching (AS-IPS) mode using V-shaped electrodes or sawtooth electrodes. In addition, the FFS mode includes: an advanced/fringe field switching (A-FFS) mode and a super/fringe field switching (U-FFS) mode using V-shaped electrodes, sawtooth electrodes, or the like.
In another embodiment, the liquid crystal layer includes: liquid crystal molecules aligned vertically in the absence of an electric field. Such a liquid crystal layer (as a result, a liquid crystal cell) representatively shows a three-dimensional refractive index nz > nx ═ ny. As a driving mode using liquid crystal molecules aligned vertically in a state where no electric field is present, for example, a Vertical Alignment (VA) mode is given. The VA mode includes a multi-domain VA (MVA) mode.
The visible-side polarizing plate and the back-side polarizing plate typically each have a polarizer and a protective layer disposed on at least one side of the polarizer. A hard coat layer of an ultraviolet-curable acrylic resin or the like, an antiglare hard coat layer, or the like may be provided on the surface of the protective layer of the rear-side polarizing plate. The polarizing element is typically an absorbing type polarizing element.
The absorption polarizer preferably has a transmittance at a wavelength of 589nm (also referred to as a "single-sheet transmittance") of 41% or more, and more preferably 42% or more. The theoretical upper limit of the single-sheet transmittance is 50%. The degree of polarization is preferably 99.5% to 100%, more preferably 99.9% to 100%. If the above range is used in a liquid crystal display device, the contrast in the front direction can be further improved.
As the polarizer, any suitable polarizer may be used. Examples thereof include: a polarizing element obtained by uniaxially stretching a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene/vinyl acetate copolymer partially saponified film, to which a dichroic material such as iodine or a dichroic dye is adsorbed; polyolefin-based oriented films such as dehydrated polyvinyl alcohol and desalted polyvinyl chloride. Among them, a polarizer obtained by uniaxially stretching a polyvinyl alcohol film having a dichroic material such as iodine adsorbed thereon has a high polarizing dichroic ratio, and is particularly preferable. The thickness of the polarizer is preferably 0.5 μm to 80 μm.
A polarizer in which iodine is adsorbed to a polyvinyl alcohol film and uniaxially stretched is typically produced as follows: the polyvinyl alcohol is dyed by immersing in an aqueous iodine solution, and stretched to 3 to 7 times the original length. The stretching may be performed after dyeing, or may be performed while dyeing, or may be performed after stretching. The fiber can be produced by, for example, subjecting the fiber to treatments such as swelling, crosslinking, conditioning, washing with water, and drying, in addition to stretching and dyeing.
As the protective layer, any suitable thin film may be used. Specific examples of the material to be the main component of such a film include cellulose resins such as Triacetylcellulose (TAC), transparent resins such as (meth) acrylic, polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyether sulfone, polysulfone, polystyrene, polynorbornene, polyolefin, and acetate. Further, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone resins, ultraviolet-curable resins, and the like can be mentioned. Further, for example, a glassy polymer such as a siloxane polymer can be given. Further, a polymer film described in Japanese patent application laid-open No. 2001-343529 (WO01/37007) can also be used. As a material of the film, for example, the following resin composition can be used: the thermoplastic resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in a side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in a side chain includes, for example, the following resin compositions: it has alternating copolymers of isobutylene and N-methylmaleimide, and acrylonitrile/styrene copolymers. The polymer film may be, for example, an extrusion-molded product of the resin composition.
Any suitable reflective polarizer may be used as long as it has a function of reflecting/transmitting linearly polarized light in the orthogonal axial direction and separating the linearly polarized light from natural light. Examples thereof include: a grid type polarizer (wire grid polarizer); the multilayer film laminate is obtained by stretching a multilayer film laminate of 2 or more layers made of 2 or more kinds of materials having a refractive index difference, vapor-deposited multilayer films having different refractive indices used in a beam splitter (beamsplitter), etc., a multilayer film laminate of 2 or more layers made of 2 or more kinds of materials having a refractive index difference, and a resin laminate of 2 or more layers made of 2 or more kinds of resins having a refractive index difference. Specifically, the following can be used: the multilayer laminate is obtained by uniaxially stretching a multilayer laminate in which a material (e.g., polyethylene naphthalate, polyethylene terephthalate, polycarbonate) or an acrylic resin (e.g., polymethyl methacrylate) exhibiting a retardation by stretching and a resin exhibiting a small amount of retardation (e.g., a norbornene resin such as ARTON manufactured by JSR corporation) are alternately laminated. Examples of commercially available products include a product name "NIPOCS APCF" manufactured by Nindon electric corporation and a product name "DBEF" manufactured by 3M. The thickness of the reflective polarizer is typically about 25 μm to 200 μm.
C-3 light modulation film
The light control film described in item B can be used as the light control film. In the case where only one of the substrate with the transparent electrode layer 1 and the substrate with the transparent electrode layer 2 of the light control film is the substrate with the transparent electrode layer described in item a, the substrate with the transparent electrode layer described in item a may be disposed so as to be positioned on the visible side (liquid crystal panel side) from the viewpoint of suitably obtaining the effect of the present invention.
C-4 surface light source device
As the surface light source device, it is possible to preferably use: and a surface light source device for emitting light having directivity in a direction substantially normal to a light emitting surface facing the light control film. By using such a surface light source device that emits light having directivity, the viewing angle at the time of narrow viewing angle display can be further reduced. Here, the "substantially normal direction" includes: a direction within a predetermined angle from the normal direction, for example, a direction within ± 10 ° from the normal direction. The phrase "light having directivity in the substantially normal direction" means light having an intensity distribution in which the peak of the maximum intensity of the intensity distribution of the luminance has an intensity distribution in the substantially normal direction with respect to the light exit surface in 1 plane orthogonal to the light exit surface, and for example, luminance at a polar angle of 40 ° or more is preferably 2% or less with respect to the normal direction (polar angle 0 °), and luminance at a polar angle of 50 ° or more is more preferably 1% or less with respect to the normal direction (polar angle 0 °). The polar angle is an angle between a normal direction (front direction) of the liquid crystal display device and light emitted from the liquid crystal display device.
As a surface light source device that emits light having directivity in a substantially normal direction of a light output surface, from the viewpoint of thinning, it is preferable to use a surface light source device of a side light type: it is provided with a light source part; and a light guide plate for receiving light from the light source unit from a side surface (light incident surface) opposite to the light source unit and emitting the light from a visible side surface (light emitting surface). The surface light source device of the side light type may be a surface light source device called a 1-lamp type in which the light source section is arranged along 1 side surface of the light guide plate, or may be a surface light source device called a 2-lamp type in which the light source section is arranged along each of 2 side surfaces facing each other of the light guide plate.
The light source unit may be configured by a plurality of point light sources arranged along a side surface of the light guide plate. The point light source is preferably a light source that emits light with high directivity, and for example, an LED can be used.
The light guide plate may have a structure capable of emitting the light having directivity. As such a light guide plate, for example, the light guide plates described in japanese patent application laid-open nos. 2000-171798 and 2005-128363 can be used. Alternatively, the light guide plate may be configured to emit light having directivity in cooperation with another optical member such as a prism sheet or a louver sheet (visor sheet) as shown in U.S. Pat. No. 5396350, U.S. Pat. No. 5555329, japanese unexamined patent publication No. 2001-305306, and japanese patent No. 3071538.
The surface light source device may further include any appropriate optical member such as a reflection plate for the purpose of improving brightness and the like. The reflective plate is typically disposed on the rear surface side of the light guide plate.
In 1 embodiment, one may use: a surface light source device emits light from a light output surface, the light having directivity in a direction substantially normal to the light output surface and containing a linearly polarized light component oscillating in a specific direction at a high ratio. In this way, by causing polarized light having directivity or partially polarized light to enter the liquid crystal panel so that the vibration direction thereof becomes parallel to the transmission axis of the rear-side polarizing plate, the utilization efficiency of light can be improved, and the viewing angle at the time of narrow viewing angle setting can be further reduced.
The linearly polarized light component vibrating in the specific direction may be, for example: a polarized light component (for example, P-polarized light component) oscillating in a plane substantially parallel to the light guiding direction of the light guide plate or a polarized light component (for example, S-polarized light component) oscillating in a direction perpendicular to the plane is more preferably the P-polarized light component. By causing the light having directivity and containing the P-polarized light component at a high ratio to enter the liquid crystal panel so that the vibration direction of the P-polarized light component coincides with the transmission axis direction of the rear-side polarizing plate, the viewing angle at the time of setting a narrow viewing angle can be further reduced as compared with the case of using light containing the S-polarized light component at a high ratio. In the case of using a light control film formed using a light-transmitting substrate having a small front retardation, the light emitted from the surface light source device can be made incident on the liquid crystal panel without substantially changing the directivity and polarization state thereof, and therefore, the effect can be more preferably obtained.
The light emitted from the surface light source device may contain the above-described linearly polarized light component oscillating in the specific direction, preferably 52% or more, more preferably 55% or more. The upper limit of the ratio of the linearly polarized light component is desirably 100%, and in 1 embodiment, 60%, and in another embodiment, 57%. The ratio of the above-mentioned linearly polarized light component in the light emitted from the surface light source device can be determined, for example, by the method described in japanese patent application laid-open No. 2013-190778.
Fig. 5 is a schematic diagram illustrating an example of a surface light source device that emits light from a light output surface, the light having directivity in a direction substantially normal to the light output surface and containing a linearly polarized light component (typically, a P-polarized light component) oscillating in a specific direction at a high ratio. The surface light source device 320 illustrated in fig. 5 includes: a light guide plate 322 for allowing light to enter from the side surface and exit from the visible side surface; a light source section 324 including a plurality of point light sources 324a arranged at predetermined intervals along a side surface (light incident surface) of the light guide plate 322; a prism sheet 326 disposed on the visible side of the light guide plate 322 and having a convex portion on the rear surface side; and a reflection plate 328 disposed on the rear surface side of the light guide plate 322. In the surface light source device 320, the following may be used: the light guide plate 322 deflects light from the lateral direction in the thickness direction, emits the light as light including a linearly polarized light component (typically, a P polarized light component) oscillating in a specific direction at a high ratio, and the prism sheet 326 having a convex portion on the back surface side makes the traveling direction thereof close to the normal direction of the light exit surface without substantially changing the polarization state of the light. As details of such a surface light source device, for example, japanese patent application laid-open No. 2013-190778 and 2013-190779 can be referred to.
In fig. 5, when the direction orthogonal to the light guiding direction of the light guide plate (the arrangement direction of the point light sources) is the X direction, the light guiding direction of the light guide plate is the Y direction, and the normal direction of the light exit surface is the Z direction, the polarization component oscillating in the YZ plane may be referred to as the P-polarization component, and the polarization component oscillating in the direction orthogonal to the YZ plane may be referred to as the S-polarization component.
Another example of a surface light source device that emits light from a light output surface, the light having directivity in a direction substantially normal to the light output surface and containing a linearly polarized light component that vibrates at a high rate in a specific direction, includes a surface light source device described in japanese patent application laid-open No. 9-54556, and a surface light source device using a polarization beam splitter, a polarization conversion element, and the like (for example, surface light source devices described in japanese patent application laid-open nos. 2013-164434, 2005-11539, 2005-128363, 07-261122, 07-270792, 09-138406, 2001-332115, and the like).
Method for manufacturing C-5 liquid crystal display device
The liquid crystal display device can be manufactured, for example, as follows: optical members such as a liquid crystal panel, a light control film, and a surface light source device are disposed in a housing to have a predetermined configuration. For example, in the case of using a surface light source device that emits light from a light output surface, the light having directivity in a direction substantially normal to the light output surface and containing a linearly polarized light component that vibrates in a specific direction at a high ratio, the surface light source device is arranged such that the vibration direction of the linearly polarized light component (preferably, a P-polarized light component) is parallel to the transmission axis of the polarizing plate on the back surface side of the liquid crystal panel. Thereby, an improvement in light utilization efficiency and further narrow viewing angle display can be achieved. Specifically, the surface light source device illustrated in fig. 5 is preferably arranged such that the light guide direction of the light guide plate (in other words, the vibration direction or Y direction of the emitted P-polarized light component) is parallel to the transmission axis of the rear-side polarizing plate of the liquid crystal display panel.