WO2017082378A1 - Optical layered body - Google Patents

Abstract

Provided is an optical layered body provided with a luminance enhancing film and an electroconductive layer, the optical layered body being configured without reduction of function of the luminance enhancing layer and electrical conductivity of the electroconductive layer. This optical layered body is provided with a polarizing plate, a luminance enhancing film, an adhesive layer, a transparent film, and an electroconductive layer, in this order. In one embodiment of the present invention, the transparent film is a film having a λ/4 plate function.

Description

Optical laminate

The present invention relates to an optical laminate.

In recent years, the configuration of display devices has become more complex, and a plurality of electronic devices are often mounted, and unnecessary electromagnetic noise is generated between the electronic devices. In order to reduce the influence of these electromagnetic noises, a conductive sheet that exhibits electromagnetic shielding characteristics is used. For example, Patent Document 1 discloses a liquid crystal display device in which a shield electrode is disposed on the side of the insulating substrate on which the liquid crystal layer is formed. In such a configuration, the pixel electrode and the common electrode are arranged at close positions, and the structure becomes very complicated.

In order to simplify the structure of the liquid crystal display device, for example, a method using an optical functional film (for example, a brightness enhancement film) on which a conductive layer is formed can be considered. However, according to such a method, heat treatment is required when forming the conductive layer, which may impair the optical function of the optical functional film. Moreover, when it heats at the temperature which can maintain the characteristic of an optical function film, there exists a possibility that the electroconductivity of a conductive layer may become inadequate.

JP 2013-15766 Gazette JP 2007-4174 A

The present invention has been made in order to solve the above-described problems, and an object of the present invention is an optical laminate including a brightness enhancement film and a conductive layer, the function of the brightness enhancement film and the conductivity of the conductive layer. An object of the present invention is to provide an optical layered body that is configured without any deterioration in properties.

The optical layered body of the present invention includes a polarizing plate, a brightness enhancement film, an adhesive layer, a transparent film, and a conductive layer in this order.
In one embodiment, the transparent film is a film having a function of a λ / 4 plate.
In one embodiment, the transparent film contains a polycarbonate resin, a cycloolefin resin, a cellulose resin, an ester resin, a polyimide resin, or an acrylic resin.
In one embodiment, the transparent film includes a cured layer or a solidified layer of a liquid crystal material.
In one embodiment, the conductive layer includes metal nanowires.
In one embodiment, the conductive layer includes a metal mesh.
In one embodiment, the conductive layer includes a metal oxide.
According to another situation of this invention, the manufacturing method of an optical laminated body is provided. This manufacturing method includes laminating a laminate A including a polarizing plate and a brightness enhancement film and a laminate B including a transparent film and a conductive layer via an adhesive layer.

According to the present invention, since the adhesive layer is disposed between the conductive layer and the brightness enhancement film, an optical laminate in which the brightness enhancement film is formed without being heated can be obtained. This optical layered body is configured without any decrease in the function of the brightness enhancement film and the conductivity of the conductive layer.

It is a schematic sectional drawing of the optical laminated body by one Embodiment of this invention. It is a schematic perspective view which shows an example of a brightness enhancement film.

A. Overall configuration diagram 1 of the optical stack is a schematic sectional view of an optical laminate according to one embodiment of the present invention. The optical laminate 100 includes a polarizing plate 10, a brightness enhancement film 20, an adhesive layer 30, a transparent film 40, and a conductive layer 50 in this order. The adhesive layer 30 means a layer containing an adhesive or a pressure-sensitive adhesive. Although not shown, the optical stack may include any other suitable member.

The optical layered body of the present invention can be obtained by bonding the conductive layer 50 disposed on the transparent film 40 to the brightness enhancement film 20 via the adhesive layer 30. Therefore, the above optical laminate can be obtained without heating the brightness enhancement film, and as a result, the brightness enhancement film fully performs its function and reduces defects such as wrinkles generated in the brightness enhancement film. Is done. In addition, since the conductive layer is formed on the transparent film and then bonded to the brightness enhancement film, it can be formed with good conductivity by heating at a desired temperature without considering damage to the brightness enhancement film. it can.

The polarizing plate 10 has a function of transmitting one polarization component (polarization component in the transmission axis direction) of two orthogonal polarization components. The brightness enhancement film separates incident light into two orthogonal polarization components, transmits one polarization component (polarization component in the transmission axis direction), and transmits the other polarization component (polarization component in the reflection axis direction). Has the function of reflecting. The transmission axis of the polarizing plate and the transmission axis of the brightness enhancement film are preferably parallel. In the present specification, the term “parallel” includes a case where they are substantially parallel, that is, includes a case where an angle formed by two straight lines is 0 ° ± 10 °, and preferably 0 ° ± 5. °, more preferably 0 ° ± 1 °.

The total light transmittance of the optical layered body is preferably 30 to 70%, more preferably 35% to 70%. In this invention, the optical laminated body comprised without impairing the light transmittance of a brightness enhancement film can be obtained, and the said optical laminated body is excellent in light transmittance. Further, by forming a conductive layer containing metal nanowires as the conductive layer, an optical laminate having a particularly high light transmittance can be obtained.

B. Polarizing plate The polarizing plate typically includes a polarizer and a protective film for protecting the polarizer.

Any appropriate polarizer is used as the polarizer. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product. Among these, a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio. The thickness of the polarizer is preferably 0.5 μm to 80 μm.

A uniaxially stretched polarizer by adsorbing iodine to a polyvinyl alcohol film is typically produced by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. The Stretching may be performed after dyeing, may be performed while dyeing, or may be performed after stretching. In addition to stretching and dyeing, for example, treatments such as swelling, crosslinking, adjustment, washing with water, and drying are performed.

任意 Any appropriate film is used as the protective film. Specific examples of the material that is the main component of such a film include cellulose resins such as triacetyl cellulose (TAC), (meth) acrylic, polyester, polyvinyl alcohol, polycarbonate, polyamide, and polyimide. And transparent resins such as polyethersulfone, polysulfone, polystyrene, polynorbornene, polyolefin, and acetate. In addition, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Further, a polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film may be an extruded product of the resin composition, for example.

C. As described above, the brightness enhancement film separates incident light into two orthogonal polarization components, transmits one polarization component (polarization component in the transmission axis direction), and transmits the other polarization component (reflection axis direction). The polarization component). The polarized light component reflected by the brightness enhancement film is reflected on another reflector (for example, a reflector provided in the backlight) to depolarize, and is incident on the brightness enhancement film again, and is polarized in the transmission axis direction. Penetrates the brightness enhancement film. By such an action, the light utilization efficiency is increased, and a brightness improvement effect is obtained. FIG. 2 is a schematic perspective view showing an example of the brightness enhancement film. Preferably, the brightness enhancement film is a multilayer laminate in which layers A having birefringence and layers B having substantially no birefringence are alternately laminated. For example, in the illustrated example, the refractive index n (x) in the x-axis direction of the A layer is larger than the refractive index n (y) in the y-axis direction, and the refractive index n (x) in the x-axis direction of the B layer and the y-axis direction. Is substantially the same as the refractive index n (y). Accordingly, the difference in refractive index between the A layer and the B layer is large in the x-axis direction and is substantially zero in the y-axis direction. As a result, the x-axis direction becomes the reflection axis, and the y-axis direction becomes the transmission axis. The refractive index difference in the x-axis direction between the A layer and the B layer is preferably 0.2 to 0.3.

The A layer is preferably made of a material that develops birefringence by stretching. Representative examples of such materials include naphthalene dicarboxylic acid polyesters (for example, polyethylene naphthalate), polycarbonates, and acrylic resins (for example, polymethyl methacrylate). Of these, polyethylene naphthalate or polycarbonate is preferable from the viewpoint of low moisture permeability. The B layer is preferably made of a material that does not substantially exhibit birefringence even when stretched. A typical example of such a material is a copolyester of naphthalenedicarboxylic acid and terephthalic acid.

The brightness enhancement film transmits light having a first polarization direction (for example, p-wave) at the interface between the A layer and the B layer, and has a second polarization direction orthogonal to the first polarization direction. Reflects light (eg, s-wave). The reflected light is partially transmitted as light having the first polarization direction and partially reflected as light having the second polarization direction at the interface between the A layer and the B layer. The light utilization efficiency can be increased by repeating such reflection and transmission many times inside the brightness enhancement film.

Preferably, the brightness enhancement film includes a reflective layer R as an outermost layer, as shown in FIG. By providing the reflective layer R, it is possible to further use the light that has not been finally used and has returned to the outermost part of the brightness enhancement film, so that the light use efficiency can be further increased. The reflective layer R typically exhibits a reflective function due to the multilayer structure of the polyester resin layer.

The overall thickness of the brightness enhancement film can be appropriately set according to the purpose, the total number of layers included in the brightness enhancement film, and the like. The total thickness of the brightness enhancement film is preferably 50 μm or less, more preferably 40 μm or less, further preferably 10 μm to 40 μm, and further preferably 20 μm to 40 μm.

As the brightness enhancement film, for example, a film described in JP-T-9-507308 can be used.

D. Adhesive layer The adhesive layer comprises any suitable adhesive or adhesive. Examples of the resin constituting the pressure-sensitive adhesive or the adhesive include acrylic resins, acrylic urethane resins, urethane resins, and silicone resins. Among these, an acrylic pressure-sensitive adhesive or acrylic adhesive containing an acrylic resin is preferable.

The adhesive layer may further contain any appropriate additive as required. Examples of the additive include a crosslinking agent, a tackifier, a plasticizer, a pigment, a dye, a filler, an anti-aging agent, a conductive material, an ultraviolet absorber, a light stabilizer, a release modifier, a softener, and a surfactant. , Flame retardants, antioxidants and the like. As the crosslinking agent, isocyanate crosslinking agent, epoxy crosslinking agent, peroxide crosslinking agent, melamine crosslinking agent, urea crosslinking agent, metal alkoxide crosslinking agent, metal chelate crosslinking agent, metal salt crosslinking agent, A carbodiimide type crosslinking agent, an oxazoline type crosslinking agent, an aziridine type crosslinking agent, an amine type crosslinking agent, etc. are mentioned.

厚 み The thickness of the adhesive layer is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm.

E. Transparent film The transparent film can function as a support when the conductive layer is formed. Any appropriate material can be used as the material constituting the transparent film. In one embodiment, a thermoplastic resin is used as a material constituting the transparent film. Excellent smoothness of the transparent film and wettability to the composition used to form the conductive layer (composition for forming conductive layer (described later)), and productivity can be greatly improved by continuous production using a roll. is there.

Preferably, a resin having excellent heat resistance is used as a material constituting the transparent film. Examples of such resins include polycarbonate resins, cycloolefin resins, cellulose resins, ester resins, polyimide resins, and acrylic resins.

In one embodiment, the transparent film is a cured or solidified layer of liquid crystal material. A transparent film composed of a cured layer or a solidified layer of a liquid crystal material can have an appropriate retardation (for example, a retardation that can function as a λ / 4 plate) and can be formed thin. Any appropriate liquid crystal monomer can be adopted as the liquid crystal material. For example, the polymerizable mesogenic compounds described in JP-T-2002-533742 (WO00 / 37585), EP358208 (US521118), EP66137 (US4388453), WO93 / 22397, EP0266172, DE195504224, DE44081171, and GB2280445 can be used. Specific examples of such a polymerizable mesogenic compound include, for example, trade name LC242 of BASF, trade name E7 of Merck, and trade name LC-Silicon-CC3767 of Wacker-Chem.

A transparent film composed of a cured layer or a solidified layer of a liquid crystal material can be obtained, for example, by aligning a liquid crystal material and solidifying or curing the alignment state in a fixed state. Specifically, a liquid crystalline composition containing a liquid crystal material is applied onto a long alignment substrate to align the liquid crystal material, and the aligned liquid crystal material is subjected to polymerization treatment and / or crosslinking treatment. And can be formed by forming a liquid crystal cured layer. Here, since the liquid crystal material can be aligned according to the alignment processing direction of the substrate, the slow axis of the retardation layer can be expressed in the same direction as the alignment processing direction of the substrate. Specific examples of the method for forming the retardation layer include the method described in JP-A-2006-178389. The thickness of the transparent film composed of the cured layer or solidified layer of the liquid crystal material is preferably 0.5 μm to 1.8 μm, more preferably 1 μm to 1.6 μm.

The heat resistant temperature of the material constituting the transparent film is preferably 90 ° C. or higher, more preferably 100 ° C. or higher, and further preferably 120 ° C. or higher. When such a material is used, a conductive layer can be formed at a high temperature, and a conductive layer having excellent conductivity can be formed. The heat-resistant temperature is a temperature at which thermal deformation does not occur and the conductive layer can be formed without any trouble.

In one embodiment, a λ / 4 plate is used as the transparent film. The λ / 4 plate can convert linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light).

The λ / 4 plate has an in-plane retardation Re of preferably 95 nm to 180 nm, more preferably 110 nm to 160 nm. The λ / 4 plate preferably has a refractive index ellipsoid of nx> ny ≧ nz. In the present specification, the in-plane retardation Re is an in-plane retardation value at 23 ° C. and a wavelength of 590 nm. Re represents the refractive index in the direction in which the in-plane refractive index is maximum (that is, the slow axis direction) as nx, and the refractive index in the direction orthogonal to the slow axis in the plane (that is, the fast axis direction). It is determined by Re = (nx−ny) × d, where ny is the film thickness d (nm). In the present specification, “ny = nz” includes not only the case where ny and nz are exactly equal, but also the case where ny and nz are substantially equal.

The λ / 4 plate is preferably a stretched polymer film. Specifically, a λ / 4 plate can be obtained by appropriately selecting the type of polymer and the stretching treatment (for example, stretching method, stretching temperature, stretching ratio, stretching direction).

任意 Any appropriate resin is used as the resin for forming the polymer film. Specific examples include resins constituting positive birefringent films such as cycloolefin resins such as polynorbornene, polycarbonate resins, cellulose resins, polyvinyl alcohol resins, polysulfone resins, and the like. Of these, norbornene resins and polycarbonate resins are preferable.

The polynorbornene is a (co) polymer obtained by using a norbornene-based monomer having a norbornene ring as a part or all of a starting material (monomer). Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl. -2-norbornene, 5-ethylidene-2-norbornene, etc., polar group-substituted products such as halogens; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene Substituents and polar group substituents such as halogen such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-Dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene and the like; Tripentamers of cyclopentadiene such as 4,9: 5,8-dimethano-3a, 4 4a, 5,8,8a, 9,9a-Octahydro-1H-benzoin 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene and the like It is done.

種 々 Various products are commercially available as the polynorbornene. Specific examples include trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, “Arton” manufactured by JSR, “TOPAS” trade name manufactured by TICONA, and trade names manufactured by Mitsui Chemicals, Inc. “APEL” may be mentioned.

芳香 Preferably, the polycarbonate-based resin is an aromatic polycarbonate. The aromatic polycarbonate can be typically obtained by a reaction between a carbonate precursor and an aromatic dihydric phenol compound. Specific examples of the carbonate precursor include phosgene, bischloroformate of dihydric phenols, diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, dinaphthyl carbonate and the like. Can be mentioned. Among these, phosgene and diphenyl carbonate are preferable. Specific examples of aromatic dihydric phenol compounds include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, and bis (4-hydroxyphenyl). ) Methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) butane, 2, 2-bis (4-hydroxy-3,5-dipropylphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethyl And cyclohexane. You may use these individually or in combination of 2 or more types. Preferably, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane are used. Used. In particular, it is preferable to use both 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane.

Examples of the cocoon stretching method include lateral uniaxial stretching, fixed-end biaxial stretching, and sequential biaxial stretching. A specific example of the fixed-end biaxial stretching includes a method of stretching a polymer film in the short direction (lateral direction) while running in the longitudinal direction. This method can be apparently lateral uniaxial stretching. Also, oblique stretching can be employed. By adopting oblique stretching, a long stretched film having an orientation axis (slow axis) at a predetermined angle with respect to the width direction can be obtained.

厚 み The thickness of the stretched film is typically 5 to 80 μm, preferably 15 to 60 μm, and more preferably 25 to 45 μm.

Further, a transparent film composed of a cured layer or a solidified layer of the above liquid crystal material may be a λ / 4 plate.

Preferably, in the λ / 4 plate, the angle formed between the absorption axis of the polarizing plate and the slow axis of the λ / 4 plate is 40 ° to 50 ° (preferably 42 ° to 48 °, more preferably 44 °. (46 °, more preferably 45 °). If it does in this way, the brightness improvement effect by the said brightness improvement film will become more remarkable. More specifically, the polarized light component (linearly polarized light) reflected by the brightness enhancement film is converted into clockwise or counterclockwise circularly polarized light by passing through the λ / 4 plate, and the circularly polarized light is Reflecting with a reflecting plate (for example, a reflecting plate of a backlight) reverses the polarization direction. Then, the reverse circularly polarized light generated by being reflected by the reflecting plate becomes polarized light that can be transmitted through the brightness enhancement film by transmitting through the λ / 4 plate. By such an action, polarized light that can be transmitted through the brightness enhancement film can be efficiently generated, and the brightness enhancement effect by the brightness enhancement film becomes more remarkable.

The transparent film functioning as a λ / 4 plate functions as a support for the conductive layer (that is, heating to the brightness enhancement film can be avoided by the presence of the transparent film). It can also serve an increase function. Furthermore, when a transparent film functioning as a λ / 4 plate is used to form a conductive layer containing metal nanowires, which will be described later, coupled with the high light transmittance of the conductive layer, the brightness enhancement effect becomes remarkable and the light transmittance is high. A laminate can be obtained.

F. Conductive layer The thickness of the conductive layer is preferably 10 nm to 5000 nm, more preferably 20 nm to 300 nm. When the conductive layer includes a polymer matrix, the thickness of the conductive layer corresponds to the thickness of the polymer matrix.

The surface resistance value of the conductive layer is preferably 0.1Ω / □ to 1000Ω / □, more preferably 0.5Ω / □ to 300Ω / □, and particularly preferably 1Ω / □ to 200Ω / □. .

The total light transmittance of the conductive layer is preferably 85% or more, more preferably 90% or more, and further preferably 95% or more.

In one embodiment, the conductive layer is patterned. Any appropriate method can be adopted as a patterning method depending on the form of the conductive layer. The shape of the pattern of the conductive layer may be any appropriate shape depending on the application. For example, the patterns described in JP-T-2011-511357, JP-A-2010-164938, JP-A-2008-310550, JP-T-2003-511799, and JP-T-2010-541109 are exemplified.

F-1. Conductive layer comprising metal nanowires or metal mesh In one embodiment, the conductive layer comprises metal nanowires or metal mesh. If a conductive layer containing metal nanowires or metal meshes is formed, an optical laminate having excellent flexibility and excellent light transmittance can be obtained.

In one embodiment, the conductive layer further comprises a polymer matrix. In this embodiment, there are metal nanowires or metal meshes in the polymer matrix. In the conductive layer composed of the polymer matrix, the metal nanowire or the metal mesh is protected by the polymer matrix. As a result, corrosion of the metal nanowire or metal mesh is prevented, and an optical laminate that is more excellent in durability can be obtained.

(Conductive layer containing metal nanowires)
A metal nanowire is a conductive material having a metal material, a needle shape or a thread shape, and a diameter of nanometer. The metal nanowire may be linear or curved. When a conductive layer composed of metal nanowires is used, the metal nanowires can be formed into a mesh shape, so that a good electrical conduction path can be formed even with a small amount of metal nanowires. Can be formed. Furthermore, when the metal nanowire has a mesh shape, an opening can be formed in the mesh space to form a conductive layer having a high light transmittance.

The ratio between the thickness d and the length L of the metal nanowire (aspect ratio: L / d) is preferably 10 to 100,000, more preferably 50 to 100,000, and particularly preferably 100 to 100,000. 10,000. If metal nanowires having a large aspect ratio are used in this way, the metal nanowires can cross well and high conductivity can be expressed by a small amount of metal nanowires. As a result, a conductive layer with high light transmittance can be formed. In the present specification, the “thickness of the metal nanowire” means the diameter when the cross section of the metal nanowire is circular, and the short diameter when the cross section of the metal nanowire is elliptical. In some cases it means the longest diagonal. The thickness and length of the metal nanowire can be confirmed by a scanning electron microscope or a transmission electron microscope.

The thickness of the metal nanowire is preferably less than 500 nm, more preferably less than 200 nm, particularly preferably 10 nm to 100 nm, and most preferably 10 nm to 50 nm. If it is such a range, a conductive layer with high light transmittance can be formed.

The length of the metal nanowire is preferably 1 μm to 1000 μm, more preferably 10 μm to 500 μm, and particularly preferably 20 μm to 100 μm. Within such a range, a conductive layer having high conductivity can be obtained.

As the metal constituting the metal nanowire, any appropriate metal can be used as long as it is a highly conductive metal. As a metal which comprises the said metal nanowire, silver, gold | metal | money, platinum, palladium, copper, nickel etc. are mentioned, for example. Moreover, you may use the material which performed the plating process (for example, gold plating process) to these metals. The metal nanowire is preferably composed of one or more metals selected from the group consisting of silver, gold, platinum, and copper. Of these, silver is preferable.

Any appropriate method can be adopted as a method for producing the metal nanowire. For example, a method of reducing silver nitrate in a solution, a method in which an applied voltage or current is applied to the precursor surface from the tip of the probe, a metal nanowire is drawn out at the probe tip, and the metal nanowire is continuously formed, etc. . In the method of reducing silver nitrate in a solution, silver nanowires can be synthesized by liquid phase reduction of a silver salt such as silver nitrate in the presence of a polyol such as ethylene glycol and polyvinylpyrrolidone. Uniform sized silver nanowires are described in, for example, Xia, Y. et al. etal. , Chem. Mater. (2002), 14, 4736-4745, Xia, Y. et al. etal. , Nano letters (2003) 3 (7), 955-960, mass production is possible.

The conductive layer containing the metal nanowires can be formed by applying a dispersion obtained by dispersing the metal nanowires in a solvent on the transparent film, and then drying the applied layer.

Examples of the solvent include water, alcohol solvents, ketone solvents, ether solvents, hydrocarbon solvents, aromatic solvents and the like. From the viewpoint of reducing the environmental load, it is preferable to use water.

The dispersion concentration of the metal nanowires in the metal nanowire dispersion liquid is preferably 0.1% by weight to 1% by weight. If it is such a range, the conductive layer excellent in electroconductivity and light transmittance can be formed.

The metal nanowire dispersion may further contain any appropriate additive depending on the purpose. Examples of the additive include a corrosion inhibitor that prevents corrosion of the metal nanowires, and a surfactant that prevents aggregation of the metal nanowires. The type, number and amount of additives used can be appropriately set according to the purpose.

Any appropriate method can be adopted as a method of applying the metal nanowire dispersion. Examples of the coating method include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, letterpress printing method, intaglio printing method, and gravure printing method. Any appropriate drying method (for example, natural drying, air drying, heat drying) can be adopted as a method for drying the coating layer. For example, in the case of heat drying, the drying temperature is typically 50 to 200 ° C., and the drying time is typically 1 to 10 minutes. The said drying temperature becomes like this. Preferably it is 90 degreeC or more, More preferably, it is 100 degreeC or more, More preferably, it is 120 degreeC or more. If it is such temperature, the conductive layer excellent in electroconductivity can be obtained. Moreover, since the optical laminated body of this invention is formed by laminating | stacking the electroconductive layer formed in the transparent film on a brightness improvement film, it can make the heating temperature at the time of electroconductive layer formation high.

The content ratio of the metal nanowires in the conductive layer is preferably 30% by weight to 90% by weight, and more preferably 45% by weight to 80% by weight with respect to the total weight of the conductive layer. If it is such a range, the conductive layer excellent in electroconductivity and light transmittance can be obtained.

When the metal nanowire is a silver nanowire, the density of the conductive layer is preferably 1.3 g / cm ³ to 10.5 g / cm ³ , more preferably 1.5 g / cm ³ to 3.0 g / cm ^3. It is. If it is such a range, the conductive layer excellent in electroconductivity and light transmittance can be obtained.

(Conductive layer including metal mesh)
The conductive layer including a metal mesh is formed by forming fine metal wires in a lattice pattern on the transparent film. Any appropriate metal can be used as the metal constituting the metal mesh as long as it is a highly conductive metal. As a metal which comprises the said metal mesh, silver, gold | metal | money, copper, nickel etc. are mentioned, for example. Moreover, you may use the material which performed the plating process (for example, gold plating process) to these metals. The metal mesh is preferably composed of one or more metals selected from the group consisting of gold, platinum, silver and copper.

The conductive layer including the metal mesh can be formed by any appropriate method. The conductive layer is formed, for example, by applying a photosensitive composition containing silver salt (composition for forming a conductive layer) onto the transparent film, and then performing an exposure process and a development process to form a thin metal wire in a predetermined pattern. Can be obtained. The conductive layer can also be obtained by printing a paste containing metal fine particles in a predetermined pattern. Details of such a conductive layer and a method for forming the same are described in, for example, Japanese Patent Application Laid-Open No. 2012-18634, the description of which is incorporated herein by reference. Another example of the conductive layer formed of a metal mesh and a method for forming the conductive layer includes a conductive layer and a method for forming the conductive layer described in JP-A-2003-331654.

(Polymer matrix)
Any appropriate polymer can be used as the polymer constituting the polymer matrix. Examples of the polymer include acrylic polymers; polyester polymers such as polyethylene terephthalate; aromatic polymers such as polystyrene, polyvinyl toluene, polyvinyl xylene, polyimide, polyamide, and polyamide imide; polyurethane polymers; epoxy polymers; Examples of the polymer include acrylonitrile-butadiene-styrene copolymer (ABS); cellulose; silicon-based polymer; polyvinyl chloride; polyacetate; polynorbornene; synthetic rubber; Preferably, polyfunctionality such as pentaerythritol triacrylate (PETA), neopentyl glycol diacrylate (NPGDA), dipentaerythritol hexaacrylate (DPHA), dipentaerythritol pentaacrylate (DPPA), trimethylolpropane triacrylate (TMPTA), etc. A curable resin composed of acrylate (preferably an ultraviolet curable resin) is used.

As described above, the polymer matrix is formed by forming a layer made of metal nanowires or metal mesh on a transparent film, applying a polymer solution on the layer, and then drying or curing the coating layer. obtain. By this operation, a conductive layer having metal nanowires or metal meshes in the polymer matrix is formed.

The polymer solution contains a polymer constituting the polymer matrix or a precursor of the polymer (a monomer constituting the polymer).

The polymer solution may contain a solvent. Examples of the solvent contained in the polymer solution include alcohol solvents, ketone solvents, tetrahydrofuran, hydrocarbon solvents, aromatic solvents, and the like. Preferably the solvent is volatile. The boiling point of the solvent is preferably 200 ° C. or lower, more preferably 150 ° C. or lower, and further preferably 100 ° C. or lower.

F-2. Conductive layer composed of metal oxide In one embodiment, the conductive layer is composed of a metal oxide. A conductive layer made of a metal oxide is formed on the transparent film by any appropriate film formation method (for example, vacuum deposition method, sputtering method, CVD method, ion plating method, spray method). It can be formed by depositing a physical film.

Examples of the metal oxide include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Of these, indium-tin composite oxide (ITO) is preferable.

G. Manufacturing method of optical laminated body It includes bonding the laminated body A containing a polarizing plate and a brightness enhancement film, and the laminated body B containing a transparent film and a conductive layer through an adhesive layer.

As the polarizing plate, the polarizing plate described in the above section B can be used. Further, as the brightness enhancement film, the brightness enhancement film described in the above section C can be used. The polarizing plate and the brightness enhancement film can be laminated by any appropriate method. For example, it can laminate | stack through an adhesive or an adhesive agent. Moreover, the laminated body A may be provided with another member.

As the transparent film, the transparent film described in the above section E can be used. As the conductive layer, the conductive layer described in the above section F can be formed. The manufacturing method of the laminated body B, that is, the method of forming the conductive layer is as described in the section F. The layered product B may include other members.

In the production method of the present invention, as described above, the laminate A and the laminate B are bonded together through an adhesive layer. In the laminated body B, a conductive layer is formed by high-temperature treatment (for example, drying) before the bonding, and by bonding such a laminated body B to the laminated body A including the brightness enhancement film, An optical laminate comprising a conductive layer can be obtained without heating the brightness enhancement film. According to such a manufacturing method, it is possible to prevent a function deterioration of the brightness enhancement film and to prevent appearance defects (for example, wrinkles) generated in the brightness enhancement film. As the adhesive layer for bonding the laminate A and the laminate B, the adhesive layer described in the above section D can be used. Any appropriate method can be adopted as a method of forming the adhesive layer.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The evaluation methods in the examples are as follows. The thickness was measured by using a scanning electron microscope “S-4800” manufactured by Hitachi High-Technologies Corporation by forming a cross section by cutting with an ultramicrotome after embedding with an epoxy resin.

(1) Surface Resistance Value The surface resistance value was measured by an eddy current method using a non-contact surface resistance meter trade name “EC-80” manufactured by Napson Corporation. The measurement temperature was 23 ° C.
(2) Retardation value The in-plane retardation value of the transparent film was measured using a trade name “KOBRA-WPR” manufactured by Oji Scientific Instruments. The measurement temperature was 23 ° C. and the measurement wavelength was 590 nm.
(3) Luminance improvement rate measurement Results (Result 1) of measuring the luminance by placing the optical laminates obtained in Examples and Comparative Examples on the backlight unit so that the polarizing plate is on the upper side, and on the backlight unit The brightness improvement rate was calculated from the result obtained by dividing only the polarizing plate (result 2) and the result obtained by dividing result 1 by result 2 (result 1 / result 2). The luminance measurement was repeated four times and the average value was taken as the measured value.
For the luminance measurement, a spectroradiometer (trade name “SR-UL1R”) manufactured by TOPCON was used. As the backlight unit, a trade name “Light Viewer 7000 PRO” manufactured by HAKUBA was used.
(4) Appearance The appearance of the brightness enhancement film included in the optical laminates obtained in the examples and comparative examples was visually confirmed.

<Production Example 1> Synthesis of Silver Nanowire and Preparation of Silver Nanowire Dispersion 1.5 g of silver nitrate, 5.8 g of polyvinylpyrrolidone K-90 (manufactured by Nacalai Tesque, average molecular weight: 360,000) as a form modifier, salt ( (NaCl) 0.04 g and ethylene glycol (180 ml) were added to a flask equipped with a reflux condenser and a stirrer, dissolved while stirring, and then the temperature was raised to 170 ° C., which is near the boiling point of ethylene glycol, for 60 minutes. Reacted. After completion of the reaction, it was allowed to cool at room temperature. Next, acetone was added to the reaction mixture containing silver nanowires obtained as described above until the volume of the reaction mixture became 5 times, and then the reaction mixture was centrifuged (2000 rpm, 20 minutes). This operation was repeated several times to obtain silver nanowires. The obtained silver nanowires had a diameter of 10 nm to 60 nm and a length of 1 μm to 50 μm. The size of the silver nanowires was measured using a scanning electron microscope “S-4800” manufactured by Hitachi High-Technologies Corporation, and the length and diameter were measured by observing 30 metal nanowires randomly extracted by the microscope. . The silver nanowire (concentration: 0.2% by weight) and pentaethylene glycol monododecyl ether (concentration: 0.1% by weight) were dispersed in pure water to prepare a silver nanowire dispersion.

<Production Example 2> Preparation of polymer solution for polymer matrix formation To 100 parts by weight of cyclopentanone, 3.0 parts by weight of pentaerythritol triacrylate (PETA) (trade name “Biscoat # 300” manufactured by Osaka Organic Chemical Industry Co., Ltd.) Then, 0.09 part by weight of a photoreaction initiator (manufactured by Ciba Japan, product name “Irgacure 907”) was added to prepare a polymer solution for forming a polymer matrix.

<Production Example 3> Production of Laminate B1 (Transparent Film / Conductive Layer) As a transparent film, a uniaxially stretched film (in-plane retardation: 140 nm) of a polycarbonate (PC) film (trade name “Carbo Glass” manufactured by Asahi Glass Co., Ltd.) ) Was used. On this transparent film, the silver nanowire dispersion liquid prepared in Production Example 1 was applied using a bar coater (product name “Bar Coater No. 15”, manufactured by Daiichi Kagaku Co., Ltd.), and it was placed in an air dryer at 120 ° C. for 2 minutes. Dried. Thereafter, the polymer solution prepared in Production Example 2 was applied with a slot die at a wet film thickness of 6 μm, and dried for 2 minutes in an air blow dryer at 80 ° C. Next, the polymer solution is cured by irradiating ultraviolet light with an integrated illuminance of 210 mJ / cm ² with an ultraviolet light irradiation device (Fusion UV Systems) made with an oxygen concentration of 100 ppm to form a conductive layer on the transparent film, A layered product B1 was obtained. The surface resistance value of the conductive layer was 49Ω / □.

<Manufacture example 4> Manufacture of laminated body B2 (transparent film / conductive layer) It replaced with the uniaxially stretched film of the polycarbonate film, and used the norbornene-type polymer (COP) film (The Nippon Zeon company make, brand name "Zeonor"). Except for this, a laminate B2 was obtained in the same manner as in Production Example 3.

<Manufacture example 5> Manufacture of laminated body B3 (transparent film / conductive layer) It replaces with the uniaxially stretched film of a polycarbonate film, and the uniaxially stretched film of the norbornene-type polymer film (The Nippon Zeon company make, brand name "ZEONOR") ( A laminate B3 was obtained in the same manner as in Production Example 3 except that the in-plane retardation: 135 nm) was used.

<Manufacture example 6> Manufacture of laminated body B4 (transparent film / conductive layer) It replaces with the uniaxially stretched film of a polycarbonate film, and the uniaxially stretched film (in-plane position of the product name "T100" by Mitsubishi resin) A laminate B4 was obtained in the same manner as in Production Example 3 except that the phase difference: 3208 nm) was used.

<Production Example 7> Production of laminate B5 (transparent film / conductive layer) A metal mesh was formed on a norbornene-based polymer film (manufactured by Nippon Zeon Co., Ltd., trade name “Zeonor”) by a method based on the method of Japanese Patent Application Laid-Open No. 2003-331654. As a result, a laminate B5 was obtained. The surface resistance value of the conductive layer formed in the laminate B5 was 30Ω / □.

<Manufacture example 8> Manufacture of laminated body B6 (transparent film / conductive layer) As a transparent film, the norbornene-type polymer (COP) film (The Nippon Zeon company make, brand name "Zeonor") was used. While mounting a sintered compact target containing indium oxide and tin oxide in a weight ratio of 90:10 and 96.7: 3.3 on a parallel plate type wind-up magnetron sputtering apparatus, while transporting a transparent film, Vacuum evacuation was performed until the partial pressure of water became 5 × 10 ⁻⁵ Pa. Thereafter, the amount of argon gas and oxygen gas introduced is adjusted, and a film is formed by DC sputtering while carrying a transparent film with a carrying speed of 10 m / min and a carrying tension of 200 to 350 N, and a 30 nm thick ITO film (conductive layer) Formed. The obtained ITO film (conductive layer) had a surface resistance of 70Ω / □.

<Manufacture example 9> Manufacture of laminated body B7 (transparent film / conductive layer) It replaces with a norbornene-type polymer film (The Nippon Zeon company make, brand name "ZEONOR"), and a norbornene-type polymer film (Nippon Zeon company make, brand name " A laminate B7 was obtained in the same manner as in Production Example 8 except that a uniaxially stretched film (Zeonor ") (in-plane retardation: 135 nm) was used.

[Example 1]
A laminate A was obtained by using a polarizing plate (manufactured by Nitto Denko Corporation, trade name “SEG1425DU”) and a brightness enhancement film (manufactured by 3M, trade name “APF-v3”) through an optical adhesive. The laminate and the laminate B1 obtained in Production Example 3 are bonded together through an adhesive layer containing an optical pressure-sensitive adhesive, and a polarizing plate, a brightness enhancement film, an adhesive layer, a transparent film, and a conductive layer are combined. The optical laminated body provided with this order was obtained.
The optical pressure-sensitive adhesive is obtained by blending 100 parts of an acrylic copolymer having a weight ratio of butyl acrylate, acrylic acid, and vinyl acetate of 100: 2: 5 with 1 part of an isocyanate-based crosslinking agent. A transparent adhesive having a coefficient of 10 N / cm ² was used.
The obtained optical laminate was subjected to the above evaluations (3) and (4). The results are shown in Table 1.

[Example 2]
An optical laminate was obtained in the same manner as in Example 1 except that the laminate B2 obtained in Production Example 4 was used instead of the laminate B1 obtained in Production Example 3.
The obtained optical laminate was subjected to the above evaluations (3) and (4). The results are shown in Table 1.

[Example 3]
An optical laminate was obtained in the same manner as in Example 1 except that the laminate B3 obtained in Production Example 5 was used instead of the laminate B1 obtained in Production Example 3.
The obtained optical laminate was subjected to the above evaluations (3) and (4). The results are shown in Table 1.

[Example 4]
An optical laminate was obtained in the same manner as in Example 1 except that the laminate B4 obtained in Production Example 6 was used instead of the laminate B1 obtained in Production Example 3.
The obtained optical laminate was subjected to the above evaluations (3) and (4). The results are shown in Table 1.

[Example 5]
An optical laminate was obtained in the same manner as in Example 1 except that the laminate B5 obtained in Production Example 7 was used instead of the laminate B1 obtained in Production Example 3.
The obtained optical laminate was subjected to the above evaluations (3) and (4). The results are shown in Table 1.

[Example 6]
An optical laminate was obtained in the same manner as in Example 1 except that the laminate B6 obtained in Production Example 8 was used instead of the laminate B1 obtained in Production Example 3.
The obtained optical laminate was subjected to the above evaluations (3) and (4). The results are shown in Table 1.

[Example 7]
An optical laminate was obtained in the same manner as in Example 1 except that the laminate B7 obtained in Production Example 9 was used instead of the laminate B1 obtained in Production Example 3.
The obtained optical laminate was subjected to the above evaluations (3) and (4). The results are shown in Table 1.

[Comparative Example 1]
A silver nanowire dispersion liquid prepared in Production Example 1 using a bar coater (product name “Bar Coater No. 10” manufactured by Daiichi Rika Co., Ltd.) on a brightness enhancement film (product name “APF-v3” manufactured by 3M) And dried for 2 minutes in a blast dryer at 120 ° C. Thereafter, the polymer solution prepared in Production Example 2 was applied with a slot die at a wet film thickness of 6 μm, and dried for 2 minutes in an air blow dryer at 80 ° C. Next, the polymer solution was cured by irradiating ultraviolet light with an integrated illuminance of 210 mJ / cm ² with an ultraviolet light irradiation device (Fusion UV Systems) with an oxygen concentration of 100 ppm, to obtain a brightness enhancement film with a conductive layer. The surface resistance value of the conductive layer was 49Ω / □.
The brightness enhancement film side of this brightness enhancement film with a conductive layer and the polarizing plate were bonded together via an optical adhesive to obtain an optical laminate.
The obtained optical laminate was subjected to the above evaluations (3) and (4). The results are shown in Table 1.

[Reference Example 1]
An optical laminate was obtained in the same manner as in Comparative Example 1 except that the drying temperature of the silver nanowire dispersion liquid was changed from 120 ° C to 70 ° C. The obtained optical laminate was subjected to the above evaluations (3) and (4). The results are shown in Table 1.

 

As is apparent from Table 1, the optical laminate of the present invention is excellent in appearance. Furthermore, if a 4 / λ plate is used as the transparent film, an optical laminate having a high luminance improvement rate can be obtained (Examples 1 and 3).

DESCRIPTION OF SYMBOLS 10 Polarizing plate 20 Brightness improvement film 30 Adhesive layer 40 Transparent film 50 Conductive layer 100 Optical laminated body

Claims (8)

1. An optical laminate comprising a polarizing plate, a brightness enhancement film, an adhesive layer, a transparent film, and a conductive layer in this order.
2. The optical laminated body according to claim 1, wherein the transparent film is a film having a function of a λ / 4 plate.
3. The optical laminate according to claim 1, wherein the transparent film contains a polycarbonate resin, a cycloolefin resin, a cellulose resin, an ester resin, a polyimide resin, or an acrylic resin.
4. The optical laminate according to claim 1, wherein the transparent film includes a cured layer or a solidified layer of a liquid crystal material.
5. The optical laminate according to claim 1, wherein the conductive layer includes a metal nanowire.
6. The optical laminate according to claim 1, wherein the conductive layer includes a metal mesh.
7. The optical laminate according to claim 1, wherein the conductive layer contains a metal oxide.
8. The manufacturing method of an optical laminated body including bonding the laminated body A containing a polarizing plate and a brightness enhancement film, and the laminated body B containing a transparent film and a conductive layer through an adhesive layer.
   
   

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