CN110392851B - Polarizing plate - Google Patents
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- CN110392851B CN110392851B CN201880017466.9A CN201880017466A CN110392851B CN 110392851 B CN110392851 B CN 110392851B CN 201880017466 A CN201880017466 A CN 201880017466A CN 110392851 B CN110392851 B CN 110392851B
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- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
Abstract
The invention provides a polarizing plate with high transmissivity, excellent smoothness and improved reflection characteristics. The polarizing plate of the present invention comprises in order: the substrate, the polarizer, and the high refractive index layer have a wavelength dependency of at least na when the refractive index in the absorption axis direction of the polarizer is na and the refractive index in the transmission axis direction is nt. In one embodiment, in the polarizing plate, the absolute value of the difference between the refractive index na (450) in the absorption axis direction of the polarizer at a wavelength of 450nm and the refractive index na (650) in the absorption axis direction of the polarizer at a wavelength of 650nm is 1.0 or more.
Description
Technical Field
The present invention relates to a polarizing plate.
Background
Liquid crystal display devices have been widely used as image display devices with low power consumption and space saving. In the liquid crystal display device, a polarizing plate is disposed on at least one side of a liquid crystal cell due to its image forming system. As liquid crystal display devices have become popular, the applications of liquid crystal display devices have been expanding, and various characteristics corresponding to such expanded applications have been required. Accordingly, polarizing plates are also required to have properties that have not been achieved and properties that are more excellent than ever, and various studies have been made to meet such requirements.
Documents of the prior art
Patent document
Patent document 1: japanese patent No. 5305997
Disclosure of Invention
Problems to be solved by the invention
The present invention has been made to solve the above conventional problems, and an object thereof is to provide a polarizing plate having high transmittance, excellent smoothness, and improved reflection characteristics.
Means for solving the problems
The polarizing plate of the present invention comprises a substrate, a polarizer and a high refractive index layer in this order, wherein when the refractive index in the absorption axis direction of the polarizer is na and the refractive index in the transmission axis direction is nt, at least na has wavelength dependence.
In one embodiment, the high refractive index layer is formed as a refractive index adjustment region in the pressure-sensitive adhesive layer.
In one embodiment, in the polarizing plate, an absolute value of a difference between a refractive index na (450) in an absorption axis direction of the polarizer at a wavelength of 450nm and a refractive index na (650) in the absorption axis direction of the polarizer at a wavelength of 650nm is 1.0 or more.
In one embodiment, the refractive index of the refractive index adjustment region is 1.60 to 2.14.
In one embodiment, a difference between the reflectance in the absorption axis direction of the polarizer and the reflectance in the transmission axis direction of the polarizer is 10% or more.
In one embodiment, the polarizer contains an aromatic disazo compound. In one embodiment, the polarizer has a thickness of 1000nm or less.
Effects of the invention
According to the present invention, a polarizing plate having high transmittance, excellent smoothness, and improved reflection characteristics that have been difficult to achieve at the same time with transmittance can be realized by using a polarizer having a specific wavelength dependence of the refractive index in combination with a high refractive index layer (in one embodiment, a refractive index adjustment region in a pressure-sensitive adhesive layer). Specifically, while maintaining the excellent properties of the polarizer, the reflectance can be reduced while the reflected color is neutral (coloring of reflected light is suppressed).
Drawings
Fig. 1 is a schematic cross-sectional view illustrating a polarizing plate according to an embodiment of the present invention.
Detailed Description
Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.
A. Integral constitution of polarizing plate
The polarizing plate of the present invention has a substrate, a polarizer, and a high refractive index layer in this order. As the high refractive index layer, a high refractive index layer having any appropriate configuration can be used. Specific examples thereof include a high refractive index layer made of a resin film having a high refractive index, a layer in which high refractive index particles are dispersed in a resin matrix (for example, such a coating layer), and a high refractive index region (for example, a refractive index adjustment region) formed in a pressure-sensitive adhesive layer. Hereinafter, a description will be given of a form in which the high refractive index layer is a refractive index adjustment region formed in the pressure-sensitive adhesive layer. It is naturally clear to the person skilled in the art that the present invention can be applied to other forms of high refractive index layers (for example, the high refractive index layer described above), and that the same effects can be obtained by such high refractive index layers.
Fig. 1 is a schematic cross-sectional view illustrating a polarizing plate according to the present embodiment. The polarizing plate 100 illustrated in the figure has a substrate 10, a polarizer 20, and an adhesive layer 30 in this order. If necessary, a protective layer (not shown) may be provided between the polarizer 20 and the adhesive layer 30. Further, a cover glass may be provided as an outermost layer of the polarizing plate (not shown) as needed. The cover glass may be provided on the outer side of the adhesive layer 30, on the outer side of the base material 10, or on both. The polarizing plate of the present invention can be typically applied to an image display device with the pressure-sensitive adhesive layer 30 disposed on the visual recognition side.
In the present invention, the refractive index of the polarizer 20 has wavelength dependence. Typically, when the refractive index of the polarizer in the absorption axis direction is na and the refractive index of the polarizer in the transmission axis direction is nt, at least na has wavelength dependence. For example, na of the polarizer has wavelength dependence (the refractive index on the long wavelength side becomes high), and nt may have flat wavelength dependence with little change depending on the wavelength. By using such a polarizer, a polarizing plate having extremely high transmittance and excellent smoothness can be obtained. The characteristics and constituent materials of the polarizer are described in detail in item C below.
Further, in the present embodiment, as described above, the refractive index adjustment region (high refractive region) is formed in the pressure-sensitive adhesive layer. In the illustrated example, the adhesive layer 30 has a base adhesive region 30a disposed on the opposite side from the polarizer 20 and a refractive index adjustment region 30b disposed on the polarizer 20 side. By disposing the adhesive layer including such a refractive index adjustment region on the visual confirmation side of the polarizer, the following advantages can be obtained. As described above, by using a polarizer having a refractive index that is wavelength-dependent, a polarizing plate having very high transmittance and excellent smoothness can be obtained. On the other hand, when a polarizing plate using such a polarizer is applied to various image display devices, a problem has been newly found that the reflectance is high and the reflected color has an undesirable coloration. According to the embodiment of the present invention, by disposing the adhesive layer including the refractive index adjustment region on the visual confirmation side of the polarizer, the reflection characteristic, which is a newly found problem in the polarizer, can be improved while maintaining the above-described excellent characteristics (high transmittance and excellent smoothness) of the polarizer. This is an unexpected and excellent effect from the knowledge obtained by repeating the trial and error on the new problem. The properties of the pressure-sensitive adhesive layer, the constituent materials, and the like are described in detail in item D below.
B. Base material
The substrate is preferably transparent and substantially optically isotropic. In the present specification, the gist of "having substantial optical isotropy" includes not only the case where the refractive index characteristic of the base material shows a relationship of nx ≈ nz ≈ ny but also the case where nx ≈ nz ≈ ny is shown. More specifically, the substantially optically isotropic phase means that the in-plane retardation Re (550) is 0nm to 10nm and the retardation Rth (550) in the thickness direction is-10 nm to +10 nm. The in-plane retardation Re (550) is preferably 0 to 5nm, more preferably 0 to 3 nm. The retardation in the thickness direction Rth (550) is preferably from-5 nm to 5nm, more preferably from-3 nm to 3 nm. Where nx is a refractive index in a direction in which the in-plane refractive index becomes maximum (i.e., the slow axis direction), ny is a refractive index in a direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and nz is a refractive index in the thickness direction. The in-plane retardation Re (. lamda.) is an in-plane retardation measured at 23 ℃ by light having a wavelength of (. lamda.nm). Therefore, Re (550) is an in-plane retardation measured by light having a wavelength of 550nm at 23 ℃. When the thickness of the layer (film) is d (nm), Re (λ) is expressed by the following formula: re (λ) ═ (nx-ny) × d. The thickness direction retardation Rth (λ) is a thickness direction retardation measured by light having a wavelength of λ nm at 23 ℃. Therefore, Rth (550) is a retardation in the thickness direction measured by light having a wavelength of 550nm at 23 ℃. Rth (lambda) is represented by the formula: rth (λ) ═ n x-nz × d.
The substrate may be made of any suitable material as long as the desired properties are obtained. Examples of the material constituting the substrate include glass, quartz, and resin. In one embodiment, the substrate may be a resin film. Typical examples of the resin include a cycloolefin resin (e.g., a norbornene resin), a polycarbonate resin, a cellulose resin (e.g., triacetyl cellulose (TAC)), (meth) acrylic resin (e.g., a (meth) acrylic resin containing a glutarimide structure). In the present specification, "(meth) acrylic" means acrylic acid and/or methacrylic acid.
The thickness of the substrate is preferably 50 to 500. mu.m, more preferably 70 to 300. mu.m, and still more preferably 80 to 300. mu.m.
The substrate may also be subjected to a specific surface treatment. For example, a hard coat layer (not shown) may be formed on the surface of the substrate opposite to the polarizer. The hard coat layer preferably has a pencil hardness of 2H or more, more preferably 3H or more. The hard coat layer may be composed of any suitable material. Specific examples of the constituent material include a thermosetting resin, a thermoplastic resin, an active energy ray-curable resin (for example, an ultraviolet ray-curable resin and an electron ray-curable resin), a two-component hybrid resin, and the like. Preferably an ultraviolet curable resin. The reason for this is that: the hard coating layer can be efficiently formed by a simple processing operation. Examples of the ultraviolet curable resin include various resins such as polyester, acrylic, urethane, amide, silicone, and epoxy resins. The thickness of the hard coat layer is, for example, about 1 μm to 5 μm.
C. Polarizer
In the present specification, the term "polarizer" refers to an element that can convert natural light or polarized light into arbitrarily polarized light. As the polarizer used in the present invention, any suitable polarizer can be used. As the polarizer, a polarizer that converts natural light or polarized light into linearly polarized light is preferably used.
As described above, the refractive index of the polarizer has wavelength dependence. For example, with respect to a polarizer, the refractive index na in the absorption axis direction has a wavelength dependence (the refractive index on the long wavelength side becomes higher), and the refractive index nt in the transmission axis direction may have a flat wavelength dependence that hardly changes even depending on the wavelength. In the polarizer, the absolute value of the difference between the refractive index na (450) in the absorption axis direction at a wavelength of 450nm and the refractive index na (650) in the absorption axis direction at a wavelength of 650nm is preferably 1.0 or more, more preferably 1.1 or more, and still more preferably 1.2 or more. The maximum value of the absolute value of the difference in the visible light wavelength region may be, for example, about 1.6. In addition, the absolute value of the difference between the refractive index na (450) in the absorption axis direction and the refractive index nt (450) in the transmission axis direction at a wavelength of 450nm is preferably 0.2 or less, more preferably 0.1 or less; the absolute value of the difference between the refractive index na (650) in the absorption axis direction and the refractive index nt (650) in the transmission axis direction at a wavelength of 650nm is preferably 1.0 or more, more preferably 1.1 or more, and still more preferably 1.2 or more. By using such a polarizer, a polarizing plate having extremely high transmittance and excellent smoothness can be obtained.
The difference between the reflectance in the absorption axis direction and the reflectance in the transmission axis direction in the polarizer may be 10% or more in one embodiment, and may be 12% or more in another embodiment. The polarizer used in the present invention has the following characteristics: as described above, the extremely excellent effects of extremely high transmittance and excellent smoothness are exhibited, and on the other hand, the difference in reflectance is large due to the wavelength dependence of the refractive index, and as a result, there is a case where the problem that the reflected color is not neutral occurs. According to the present invention, when such a polarizer is used in combination with an adhesive layer containing a refractive index adjustment region, the reflection characteristics can be significantly improved while maintaining the excellent characteristics of the polarizer.
The polarizer preferably exhibits absorption dichroism at any wavelength of 380nm to 780 nm. The monomer transmittance of the polarizer is preferably 43.0% to 46.0%, more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.
The polarizer may be made of any suitable material as long as it has the desired characteristics described above. In one embodiment, the polarizer is an oriented cured layer or an oriented hardened layer of lyotropic liquid crystal. In the present specification, the term "lyotropic liquid crystal" refers to a liquid crystal in which phase transition between an isotropic phase and a liquid crystal phase is caused by changing the temperature or the concentration of a solute (liquid crystal compound). The "cured layer" is a layer in a state in which the liquid crystalline composition in a softened, molten or solution state is cooled to be cured, and the "hardened layer" is a layer in which a part or all of the liquid crystalline composition is crosslinked by heat, a catalyst, light and/or radiation and is in an insoluble or hardly soluble state.
Examples of the lyotropic liquid crystal include azo dyes, anthraquinone dyes, perylene dyes, indanthrene dyes, imidazole dyes, indigo dyes, oxazine dyes, phthalocyanine dyes, triphenylmethane dyes, pyrazolone dyes, stilbene dyes, diphenylmethane dyes, naphthoquinone dyes, methylcyanine dyes, quinophthalone dyes, xanthene dyes, alizarin dyes, acridine dyes, quinoneimine dyes, thiazole dyes, methine dyes, nitro dyes, and nitroso dyes according to a classification based on a chemical structure.
The polarizer preferably contains an aromatic disazo compound. The aromatic disazo compound is preferably represented by the following general formula (1).
In the general formula (1)In, Q1Represents a substituted or unsubstituted aryl group, Q2Represents a substituted or unsubstituted arylene radical, R1Independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acetyl group, a substituted or unsubstituted benzoyl group, a substituted or unsubstituted phenyl group, M represents a counter ion, M represents an integer of 0 to 2, and n represents an integer of 0 to 6. Wherein at least one of m and n is not 0, and 1. ltoreq. m + n. ltoreq.6. In the case where m is 2, each R1The same or different. OH and (NHR) represented by the general formula (1)1)mAnd (SO)3M)nEach of the 7 substituents of the naphthalene ring may be bonded to one of the substituents. In the present specification, the term "substituted or unsubstituted" means "substituted or unsubstituted with a substituent".
The bonding position between the naphthyl group of the general formula (1) and the azo group (-N ═ N-) is not particularly limited. The above naphthyl group means a naphthyl group represented on the right side in formula (1). Preferably, the naphthyl group and the azo group are bonded to each other at the 1-position or the 2-position of the naphthyl group.
In R of the general formula (1)1When the alkyl group, acetyl group, benzoyl group or phenyl group in (1) has a substituent, examples of the substituent include the substituents exemplified below for aryl groups and arylene groups. R is as defined above1Preferably a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acetyl group, and more preferably a hydrogen atom. Examples of the substituted or unsubstituted alkyl group include substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms.
M (counter ion) in the general formula (1) preferably includes hydrogen ion; alkali metal ions such as Li, Na, K, Cs and the like; ca. Alkaline earth metal ions such as Sr and Ba; other metal ions; ammonium ions which may be substituted by alkyl or hydroxyalkyl groups; salts of organic amines, and the like. Examples of the metal ion include Ni+、Fe3+、Cu2+、Ag+、Zn2+、Al3+、Pd2+、Cd2+、Sn2+、Co2+、Mn2+、Ce3 +. The organic amine includes an alkylamine having 1 to 6 carbon atomsAlkyl amine having 1 to 6 carbon atoms and having a hydroxyl group, alkyl amine having 1 to 6 carbon atoms and having a carboxyl group, and the like. In the general formula (1), in SO3When M is two or more, M may be the same or different. In addition, in the general formula (1), in SO3When M of M is a divalent or higher cation, it may be bonded to SO of another adjacent azo compound of the formula (1)3 -Bonding to form a supramolecular association.
M of the general formula (1) is preferably 1. In addition, n in the general formula (1) is preferably 1 or 2.
Specific examples of the naphthyl group of the general formula (1) include naphthyl groups represented by the following formulae (a) to (l). R of formulae (a) to (l)1And M is the same as in the general formula (1).
In the general formula (1), Q is as defined above1Examples of the aryl group include, in addition to a phenyl group, a condensed ring group obtained by condensing two or more benzene rings such as a naphthyl group. Above Q2Examples of the arylene group include a condensed ring group obtained by condensing two or more benzene rings such as naphthylene, in addition to phenylene.
Q1Aryl or Q of2The arylene group of (a) may have a substituent, respectively, or may have no substituent. When the aryl group or the arylene group is either substituted or unsubstituted, the aromatic disazo compound of the general formula (1) having a polar group is excellent in solubility in an aqueous solvent.
When the aryl group or the arylene group has a substituent, examples of the substituent include a carboxyl group such as an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylamino group having 1 to 6 carbon atoms, a phenylamino group, an acylamino group having 1 to 6 carbon atoms, a dihydroxypropyl group and the like having 1 to 6 carbon atoms, a COOM group and the like, SO3Sulfonic acid groups such as M group, hydroxyl group, cyano group, nitro group, amino group, halogen group and the like. The substituent is preferably selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms,One of hydroxyalkyl group having 1 to 6 carbon atoms, carboxyl group, sulfonic group and nitro group. The aromatic disazo compound having such a substituent is particularly excellent in water solubility. These substituents may be substituted by one or two or more. The substituents may be substituted at an arbitrary ratio.
Q of the formula (1)1The substituted or unsubstituted phenyl group is preferable, and the phenyl group having the above substituent is more preferable. Q2Preferred is a substituted or unsubstituted naphthylene group, more preferred is a naphthylene group having the above-mentioned substituent, and particularly preferred is a 1, 4-naphthylene group having the above-mentioned substituent.
Q of the formula (1)1Is substituted or unsubstituted phenyl, and Q2The aromatic disazo compound which is a substituted or unsubstituted 1, 4-naphthylene group is represented by the following general formula (2).
In the general formula (2), R1M, m and n are the same as those in the above general formula (1). In the general formula (2), A and B represent substituents, and a and B represent the number of substitution. A and B independently represent a carboxyl group such as an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylamino group having 1 to 6 carbon atoms, a phenylamino group, an acylamino group having 1 to 6 carbon atoms, a dihydroxypropyl group or the like having 1 to 6 carbon atoms, a COOM group or the like, SO3A sulfonic acid group such as an M group, a hydroxyl group, a cyano group, a nitro group, an amino group, or a halogen group. A is an integer of 0 to 5, and b is an integer of 0 to 4. Wherein at least one of a and b is not 0. When a is 2 or more, the substituents a may be the same or different. When B is 2 or more, the substituents B may be the same or different.
Among the aromatic disazo compounds contained in the general formula (2), an aromatic disazo compound represented by the following general formula (3) is preferably used. The aromatic disazo compound of the formula (3) has a substituent A bonded to the para-position based on an azo group (-N-). Further, the aromatic disazo compound of the formula (3) has the naphthyl group bonded at the position (ortho position) adjacent to the azo group via the OH group. When the aromatic disazo compound of the general formula (3) is used, a polarizer which is less likely to shrink by heating can be formed.
In the general formula (3), R1M, m and n are the same as those in the above general formula (1), and A is the same as those in the general formula (2). In the general formula (3), p represents an integer of 0 to 4. P is preferably 1 or 2, more preferably 1.
The aromatic disazo compounds represented by the general formulae (1) to (3) can be synthesized, for example, according to "theoretical dyestuff chemistry (5 th edition)" manufactured by Hipport, Ministry 7, 15, 1968, pp.135 to 152. For example, the aromatic disazo compound of the general formula (3) can be synthesized by diazotizing and coupling an aniline derivative and a naphthalenesulfonic acid derivative to obtain a monoazo compound, diazotizing the monoazo compound, and further coupling the monoazo compound with a 1-amino-8-naphtholsulfonic acid derivative.
As the thickness of the polarizer, any appropriate thickness may be adopted according to the purpose. The lower limit of the thickness of the polarizer is preferably 100nm, more preferably 200nm, and particularly preferably 300 nm. The upper limit of the thickness of the polarizer is preferably 1000nm, more preferably 700nm, and particularly preferably 500 nm.
The polarizer can be formed by a method including, for example, the following steps a to D.
Step A: mixing lyotropic liquid crystals with a solvent (e.g., water) to prepare a solution exhibiting a liquid crystal phase (e.g., a nematic liquid crystal phase);
and a step B: carrying out orientation treatment on the base material;
and a step C: coating the solution obtained in the step A on the surface of the substrate subjected to the orientation treatment;
step D: the coating film is dried.
D. Adhesive layer
As described above, the adhesive layer 30 has the base adhesive region 30a disposed on the opposite side from the polarizer 20 and the refractive index adjustment region 30b disposed on the polarizer 20 side. The base adhesive region 30a representatively may be composed of an adhesive base material (e.g., a general adhesive). The refractive index adjustment region 30b has a higher refractive index than the base adhesive region 30 a. By using an adhesive layer having a refractive index adjusting region, the reflection characteristics of the polarizing plate can be significantly improved while maintaining the excellent characteristics of the polarizer described in the above item C.
As the adhesive base material, any suitable material can be used as long as it has an adhesive property and transparency that can be used for optical purposes. Specific examples thereof include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. The adhesive base material may be used alone, or two or more kinds may be used in combination. From the viewpoint of transparency, processability, durability and the like, an acrylic adhesive is preferable. The refractive index of the adhesive base material is typically 1.40 to 1.55.
In one embodiment, the refractive index adjustment region 30b may be composed of a resin material having a higher refractive index than the adhesive base material. The refractive index of the resin material is, for example, 1.59 to 2.04. Examples of such a resin material include a styrene-based resin and a copolymer resin containing a styrene-based monomer as a monomer unit. The resin material may be, for example, an acrylic polymer containing, as a monomer unit, at least one aromatic ring-containing copolymerizable monomer selected from aromatic ring-containing acrylic monomers and styrenic monomers. Details of such a material are described in, for example, japanese patent laid-open publication No. 2002-173656. The description of this publication is incorporated herein by reference. The refractive index adjustment region can be formed by, for example, applying a solution or dispersion of such a resin material to the surface of a pressure-sensitive adhesive layer (which ultimately becomes a base pressure-sensitive adhesive region) formed of a pressure-sensitive adhesive base material and drying the applied solution or dispersion.
In another embodiment, the refractive index is modulatedThe entire region 30b may be formed by dispersing particles of the high refractive index material in the binder base material. The refractive index of the high refractive index material particles may be, for example, 1.60 to 2.74. The difference between the refractive index of the high refractive index material particles and the refractive index of the binder base material is preferably 0.20 to 1.30. Specific examples of the material constituting the high refractive index material particles include TiO2、ZrO2、CeO2、Al2O3、BaTiO2、Nb2O5And SnO2And combinations thereof. The average primary particle diameter of the high refractive index material particles is preferably 3nm to 100 nm. The refractive index adjustment region can be formed, for example, by applying a coating treatment liquid in which high refractive index material particles are dispersed to a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive base material, and impregnating the pressure-sensitive adhesive base material with the high refractive index material particles to form a fixed region extending in the thickness direction of the pressure-sensitive adhesive layer. The refractive index of the refractive index adjustment region formed in this way can be, for example, 1.60 to 2.14.
The thickness of the adhesive layer may be any appropriate thickness according to the purpose. The thickness of the pressure-sensitive adhesive layer is, for example, 5 to 500. mu.m, preferably 10 to 300. mu.m, and more preferably 20 to 200. mu.m. Among them, the thickness of the refractive index adjustment region is preferably 20nm to 600nm, more preferably 20nm to 300nm, and still more preferably 20nm to 200 nm. As shown in fig. 1, the boundary between the base adhesive region and the refractive index adjustment region has irregular fine irregularities (the thickness and the irregularities of the refractive index adjustment region are emphasized in fig. 1 for easy visibility). The thickness of the refractive index adjustment region is determined by averaging the thicknesses at a plurality of positions. The thickness of each of the plurality of positions was determined as the thickness of the region where 90% of the high refractive index material particles were present. The thickness of the base adhesive region is determined by subtracting the thickness of the refractive index adjustment region from the entire thickness of the adhesive layer.
The higher the total light transmittance of the adhesive layer is, the more preferable. The total light transmittance of the adhesive layer is preferably 80% or more, more preferably 90% or more. The total light transmittance can be measured according to JIS K7361.
Details of adhesive layers comprising refractive index adjustment regions are described in, for example, WO 2015/108159. The description of this publication is incorporated herein by reference.
Examples
The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The measurement methods of the characteristics in the examples are as follows. Unless otherwise specified, "parts" and "%" in the examples are based on weight.
(1) Refractive index
The average refractive index was measured using an Abbe refractometer manufactured by Atago.
(2) Reflectance and reflected hue
The polarizing plates obtained in examples and comparative examples were attached to a blackboard via an adhesive. Further, a glass plate was bonded to the adhesive layer of the polarizing plate to produce a substitute for an image display device. The obtained image display device substitute was measured for reflection hue and reflectance using a spectrocolorimeter "CM-2600 d" manufactured by Konica Minolta corporation. The reflectance was measured for light with an incident angle of 2 ° and 30 °, respectively.
< example 1>
1. Synthesis of organic pigment (lyotropic liquid Crystal)
4-nitroaniline and 8-amino-2-naphthalenesulfonic acid were subjected to diazotization and coupling reaction by a conventional method (Seikagan Seisakusho, 5 th edition of the theoretical dyestuff chemistry, 7.7.15.tech., 1968, pages 135 to 152) to obtain a monoazo compound. The obtained monoazo compound was diazotized by the above-mentioned conventional method, and further subjected to coupling reaction with 1-amino-8-naphthol-2, 4-disulfonic acid lithium salt to obtain a crude product. By salting out it with lithium chloride, an aromatic disazo compound represented by the following structural formula (4) is obtained.
2. Production of polarizer
The aromatic disazo compound of the above structural formula (4) was dissolved in ion-exchanged water to prepare a coating liquid having a concentration of 4% by weight. The coating liquid exhibits a nematic liquid crystal phase. On the other hand, a norbornene resin film (manufactured by Zeon Corporation, product name "ZEONOR", Re (550) ═ 1nm, Rth (550) ═ 3nm) was prepared as a base material, and the surface of the film was subjected to a rubbing treatment and a hydrophilization treatment (corona treatment). On the treated surface, a coating liquid was applied by using a bar coater (product name "Mayer rot HS 4" manufactured by BUSHMAN Co.), and the coating film was naturally dried in a constant temperature room at 23 ℃ to form a dried coating film (polarizer) on the surface of the substrate. The thickness of the obtained polarizer was 300nm, na (450) was 1.4, and na (650) was 2.7.
3. Formation of adhesive layer containing refractive index adjustment region
3-1 preparation of adhesive base Material
60 parts by weight of dicyclopentanyl acrylate (DCPMA), 40 parts by weight of Methyl Methacrylate (MMA), 3.5 parts by weight of alpha-thioglycerol as a chain transfer agent, and 100 parts by weight of toluene as a polymerization solvent were put into a four-necked flask, and they were stirred at 70 ℃ for 1 hour under a nitrogen atmosphere. Then, 0.2 part by weight of 2,2' -azobisisobutyronitrile as a polymerization initiator was put into a four-necked flask, and reacted at 70 ℃ for 2 hours and then at 80 ℃ for 2 hours. Thereafter, the reaction mixture was charged at a temperature of 130 ℃ and toluene, a chain transfer agent and an unreacted monomer were removed by drying, thereby obtaining a solid acrylic polymer (A-1). The weight-average molecular weight (Mw) of the acrylic polymer (A-1) was 5.1X 103。
On the other hand, a prepolymer composition was obtained by polymerizing a part of the monomer components described above, by adding 0.035 parts by weight of a photopolymerization initiator (trade name "Irgacure 184", manufactured by BASF corporation) and 0.035 parts by weight of a photopolymerization initiator (trade name "Irgacure 651", manufactured by BASF corporation) to a monomer mixture comprising 68 parts by weight of 2-ethylhexyl acrylate (2EHA), 14.5 parts by weight of N-vinyl-2-pyrrolidone (NVP) and 17.5 parts by weight of 2-hydroxyethyl acrylate (HEA), and then irradiating with ultraviolet light until the viscosity became about 20 pas (measurement conditions: BH viscometer No.5 spindle, 10rpm, measurement temperature 30 ℃ C.).
3-2 formation of adhesive layer (base adhesive region)
Then, 5 parts by weight of the acrylic polymer (A-1), 0.15 parts by weight of hexanediol diacrylate (HDDA), and 0.3 parts by weight of a silane coupling agent (trade name "KBM-403", manufactured by shin-Etsu chemical Co., Ltd.) were added to the prepolymer composition and mixed to obtain an acrylic pressure-sensitive adhesive composition. The acrylic pressure-sensitive adhesive composition was applied to a release-treated surface of a release film (trade name "MRF # 38", manufactured by mitsubishi resin co., ltd.) so that the thickness after the pressure-sensitive adhesive layer was formed became 150 μm to form a coating layer, and then a release film (trade name "MRN # 38", manufactured by mitsubishi resin co., ltd.) was attached to the surface of the coating layer. After that, in the illuminance: 5mW/cm2Light quantity: 1500mJ/cm2Ultraviolet irradiation was performed under the conditions of (1) and the coating layer was photo-cured to form a pressure-sensitive adhesive layer (refractive index: 1.48).
3-3 formation of refractive index adjustment region
As the coating treatment liquid in which the high refractive index material particles are dispersed, a dispersion liquid manufactured by CIKnanoTek (co., ltd.) is used. The dispersion is prepared by mixing zirconia particles (ZrO)2Refractive index: 2.17, average primary particle diameter: 20nm) in ethanol (particle concentration: 1.5 wt%, transmittance of dispersion: 75%). The average primary particle size of the zirconia particles was measured from a TEM image.
From the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) obtained in the above 3-2, to both sides of which release films were temporarily adhered, one release film was peeled off and removed. The coating treatment liquid was applied to the exposed surface of the pressure-sensitive adhesive layer by a bar coater RDS No.5 so that the thickness of the refractive index adjustment region became 20nm to 300nm, and dried in a drying oven at 110 ℃ for 180 seconds. The refractive index adjustment region (refractive index: 1.62) was formed by the above operation. Next, a release film was attached to the surface of the pressure-sensitive adhesive layer on which the refractive index adjustment region was formed, to obtain a pressure-sensitive adhesive sheet.
4. Preparation of polarizing plate
The adhesive sheet obtained in 3-3 above was bonded to the polarizer surface of the substrate/polarizer laminate obtained in 2 above, so that the refractive index adjustment region was on the polarizer side. In this manner, a polarizing plate having a structure of substrate/polarizer/refractive index adjustment region/base adhesive region was obtained. The obtained polarizing plate was subjected to the evaluation of the above (2). The results are shown in table 1.
< comparative example 1>
A polarizing plate was produced in the same manner as in example 1, except that no refractive index adjustment region was formed in the pressure-sensitive adhesive layer. The same evaluation as in example 1 was performed using the obtained polarizing plate. The results are shown in table 1.
[ Table 1]
< evaluation >
As is clear from table 1, it is understood that the reflection color phase becomes more neutral and the reflectance can be suppressed by forming the high refractive index layer (in the example, the refractive index adjustment region in the pressure-sensitive adhesive layer).
Industrial applicability
The polarizing plate of the present invention can be used for various image display devices for various applications such as portable information terminals (PDAs), portable devices such as mobile phones, clocks, digital cameras, portable game machines, computer monitors, OA devices such as notebook computers and copying machines, home electric devices such as video cameras, liquid crystal televisions and microwave ovens, in-vehicle devices such as instrument panels, rear monitors, monitors for car navigation systems, car audio devices, display devices such as information monitors for commercial stores, police devices such as monitors, nursing care such as medical monitors, and medical devices.
Description of the symbols
10 base material
20 polarizer
30 adhesive layer
30a base adhesive region
30b refractive index adjustment region
100 polarizing plate
Claims (3)
1. A polarizing plate having a substrate, a polarizer directly formed on the substrate, and an adhesive layer directly formed on the polarizer, wherein,
a refractive index adjustment region is formed on the polarizer side of the adhesive layer, the refractive index adjustment region is a high refractive index layer having a refractive index of 1.60 to 2.14, the refractive index adjustment region is a region in which high refractive material particles are dispersed in an adhesive base material, the refractive index of the high refractive material particles is 1.60 to 2.74,
the polarizer contains an aromatic disazo compound represented by the following formula (1), wherein the thickness of the aromatic disazo compound is 1000nm or less, and when the refractive index of the polarizer in the absorption axis direction is na and the refractive index of the polarizer in the transmission axis direction is nt, at least na has wavelength dependence,
in formula (1), Q1Represents a substituted or unsubstituted aryl group, Q2Represents a substituted or unsubstituted arylene radical, R1Independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acetyl group, a substituted or unsubstituted benzoyl group, a substituted or unsubstituted phenyl group, M represents a counter ion, M represents an integer of 0 to 2, and n represents an integer of 0 to 6; wherein at least one of m and n is not 0, and 1. ltoreq. m + n. ltoreq.6; in case m is 2, R1Each may be the same or different.
2. The polarizing plate according to claim 1, wherein an absolute value of a difference between a refractive index na (450) in an absorption axis direction of the polarizer at a wavelength of 450nm and a refractive index na (650) in the absorption axis direction of the polarizer at a wavelength of 650nm is 1.0 or more.
3. The polarizing plate according to claim 1, wherein a difference between a reflectance in an absorption axis direction of the polarizer and a reflectance in a transmission axis direction of the polarizer is 10% or more.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017049744A JP7048213B2 (en) | 2017-03-15 | 2017-03-15 | Polarizer |
| JP2017-049744 | 2017-03-15 | ||
| PCT/JP2018/005940 WO2018168351A1 (en) | 2017-03-15 | 2018-02-20 | Polarizing plate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110392851A CN110392851A (en) | 2019-10-29 |
| CN110392851B true CN110392851B (en) | 2022-05-17 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201880017466.9A Active CN110392851B (en) | 2017-03-15 | 2018-02-20 | Polarizing plate |
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| JP (1) | JP7048213B2 (en) |
| KR (1) | KR20190126071A (en) |
| CN (1) | CN110392851B (en) |
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| WO (1) | WO2018168351A1 (en) |
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| WO2019151334A1 (en) * | 2018-01-30 | 2019-08-08 | 富士フイルム株式会社 | Polarization plate, circular polarization plate, and display device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101636470A (en) * | 2008-01-24 | 2010-01-27 | 日东电工株式会社 | Liquid-crystalline coating fluid and polarizing film |
| CN106030354A (en) * | 2014-06-06 | 2016-10-12 | 日东电工株式会社 | Projection device and vehicle |
| WO2017014243A1 (en) * | 2015-07-22 | 2017-01-26 | 日東電工株式会社 | Polarizing film laminate having transparent adhesive layer and patterned transparent conductive layer, and liquid crystal panel and organic el panel |
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| JPS6055878B2 (en) | 1976-07-06 | 1985-12-06 | オムロン株式会社 | Security equipment for transaction processing equipment |
| JP2004133171A (en) * | 2002-10-10 | 2004-04-30 | Konica Minolta Holdings Inc | Optical compensation sheet and liquid crystal display device |
| KR101070481B1 (en) * | 2004-06-30 | 2011-10-05 | 엘지디스플레이 주식회사 | Polarization film and lcd device of using the same |
| JP2010134349A (en) * | 2008-12-08 | 2010-06-17 | Sony Corp | Liquid crystal display device |
| JP2012068377A (en) * | 2010-09-22 | 2012-04-05 | Toppan Printing Co Ltd | Antireflection film, polarizing plate, and transmissive liquid crystal display device |
| JP6024586B2 (en) * | 2013-04-30 | 2016-11-16 | コニカミノルタ株式会社 | Glass with polarization function and liquid crystal display device having the same |
| JP2015200866A (en) * | 2014-03-31 | 2015-11-12 | 日東電工株式会社 | Optical member, polarizing plate set and liquid crystal display apparatus |
| JP6152068B2 (en) * | 2014-04-09 | 2017-06-21 | 富士フイルム株式会社 | Polarizing plate and image display device |
| CN106795416A (en) * | 2014-06-18 | 2017-05-31 | 王子控股株式会社 | Polarizer adhesive composition and polarizer bonding sheet |
| JP6404175B2 (en) * | 2015-04-24 | 2018-10-10 | 株式会社ポラテクノ | Optical filter and imaging apparatus and image forming apparatus using the same |
-
2017
- 2017-03-15 JP JP2017049744A patent/JP7048213B2/en active Active
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2018
- 2018-02-20 CN CN201880017466.9A patent/CN110392851B/en active Active
- 2018-02-20 WO PCT/JP2018/005940 patent/WO2018168351A1/en active Application Filing
- 2018-02-20 KR KR1020197025359A patent/KR20190126071A/en active IP Right Grant
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101636470A (en) * | 2008-01-24 | 2010-01-27 | 日东电工株式会社 | Liquid-crystalline coating fluid and polarizing film |
| CN106030354A (en) * | 2014-06-06 | 2016-10-12 | 日东电工株式会社 | Projection device and vehicle |
| WO2017014243A1 (en) * | 2015-07-22 | 2017-01-26 | 日東電工株式会社 | Polarizing film laminate having transparent adhesive layer and patterned transparent conductive layer, and liquid crystal panel and organic el panel |
Also Published As
| Publication number | Publication date |
|---|---|
| JP7048213B2 (en) | 2022-04-05 |
| CN110392851A (en) | 2019-10-29 |
| JP2018151603A (en) | 2018-09-27 |
| WO2018168351A1 (en) | 2018-09-20 |
| TW201837508A (en) | 2018-10-16 |
| TWI762601B (en) | 2022-05-01 |
| KR20190126071A (en) | 2019-11-08 |
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