WO2015125656A1

WO2015125656A1 - Polarizing plate, optical-member set, and touchscreen

Info

Publication number: WO2015125656A1
Application number: PCT/JP2015/053587
Authority: WO
Inventors: 慶史小松
Original assignee: 住友化学株式会社
Priority date: 2014-02-21
Filing date: 2015-02-10
Publication date: 2015-08-27
Also published as: JP5886338B2; KR20160098521A; JP2015156003A; TWI618952B; TW201539063A; CN106030353A; KR20170018092A; CN106030353B; KR101711357B1; KR102084297B1

Abstract

This invention provides the following: a polarizing plate that contains a polarizer and a first optical film laminated to one surface of said polarizer, wherein a profile curve of the surface of the first optical film that faces away from the polarizer exhibits a kurtosis (Pku) of at least 3.0, and when light is incident thereon at an angle of incidence of 12°, said surface exhibits a reflectance (Y) of at most 4.0% at an angle of reflection of 12°; and an optical-member set and a touchscreen that contain the aforementioned polarizing plate.

Description

Polarizing plate, optical member set, and touch input type image display device

The present invention relates to a polarizing plate that can be suitably used for an air gap type touch input type image display device, an optical member set including the same, and a touch input type image display device.

In recent years, touch-input type image display devices have been rapidly spread mainly in smartphones and tablet-type portable information terminals. The touch input type image display device includes a touch input element (touch panel) for detecting touch position information on the viewing side of the image display element or inside the image display element, and the image display element is a liquid crystal cell or organic electroluminescence. In the case of an (EL) display element or the like, the touch input type image display device is generally configured to include a polarizing plate.

There are various types of touch input type image display devices, but the resistive film type and the electrostatic capacity type are mainly used at present. In the resistive film method, two substrates having transparent electrodes are arranged so that the transparent electrodes are opposed to each other, and the two transparent electrodes facing each other when touching the screen with a finger or the like are in contact with each other. To detect the touch position. Thus, in the resistive film system, a gap is provided between two substrates.

On the other hand, the electrostatic capacity method detects a touch position by detecting a change in surface charge of a portion touched with a finger or the like. Some electrostatic capacity systems have a configuration in which a gap is provided in a touch input type image display device. Below, what provided the gap | interval (air gap) in the touch input type image display apparatus is also called the touch input type image display apparatus of an "air gap type".

Japanese Patent Application Laid-Open No. 2008-155387 (Patent Document 1) describes that a laminated body in which a transparent conductive film is formed on an uneven surface of a resin molded body is used as a substrate with a transparent electrode for a touch panel. Japanese Patent Application Laid-Open No. 2011-133881 (Patent Document 2) discloses a polarizing plate, a retardation film, a hard coat layer, and a transparent conductive film as one substrate (a viewing-side substrate) in a resistive film type touch panel. It is described that a laminate including in order is used (FIG. 9).

JP 2008-155387 A JP 2011-133881 A

In an air gap type touch-input type image display device, when the screen is touched with a finger or the like, the interval of the air gap changes, and as a result, the light reflected in the air gap interferes with the Newton. Interference fringes called rings are likely to occur. When Newton rings occur, the visibility of the display screen is reduced.

In Patent Document 1, Newton's ring can be suppressed by roughening the surface of the resin molded body on which the transparent conductive film is formed, specifically, by setting the arithmetic average roughness Ra to 50 to 150 nm. However, when the arithmetic average roughness Ra is controlled, the Newton ring may not necessarily be effectively suppressed particularly when the arithmetic average roughness Ra is at a level of 100 nm or less. In Patent Document 2, Newton's ring and glare can be suppressed by controlling the arithmetic average roughness Ra of the surface on the side where the transparent conductive film is formed in the hard coat layer and the number of protrusions having a predetermined height. However, like Patent Document 1, Newton's ring may not be effectively suppressed.

An object of the present invention is to provide a polarizing plate capable of effectively suppressing the generation of Newton rings, an optical member set including the polarizing plate, and a touch input type image display device.

The present invention provides the following polarizing plate, optical member set and touch input type image display device.

[1] A polarizer and a first optical film laminated on one surface thereof,
The surface of the first optical film opposite to the polarizer has a cross-sectional curve kurtosis Pku of 3.0 or more, and a reflectance at a reflection angle of 12 ° when light is incident at an incident angle of 12 °. The polarizing plate whose Y is 4.0% or less.

[2] The polarizing plate according to [1], wherein the first optical film includes a first thermoplastic resin film and an optical layer laminated on a surface opposite to the polarizer.

[3] The polarizing plate according to [2], wherein the first thermoplastic resin film is made of a cellulose resin, a (meth) acrylic resin, a cyclic polyolefin resin, or a polyester resin.

[4] The polarizing plate according to any one of [1] to [3], further including a second optical film laminated on a surface of the polarizer opposite to the first optical film.

[5] The polarizing plate according to [4], wherein the second optical film includes a second thermoplastic resin film made of a cellulose resin, a (meth) acrylic resin, or a cyclic polyolefin resin.

[6] The polarizing plate according to [4] or [5], wherein the second optical film is a retardation film.

[7] The polarizing plate according to any one of [1] to [6],
A translucent member to be disposed on the first optical film side in the polarizing plate;
An optical member set for a touch input type image display device.

[8] An image display element;
The polarizing plate according to any one of [1] to [6] disposed on the viewing side of the image display element;
On the side of the first optical film in the polarizing plate, a translucent member disposed apart from the first optical film,
A touch input type image display device.

[9] The touch input type image display device according to [8], wherein the translucent member is a touch input element.

According to the present invention, it is possible to provide a polarizing plate capable of effectively suppressing the occurrence of Newton rings, an optical member set including the polarizing plate, and a touch input type image display device.

It is a schematic sectional drawing which shows an example of the polarizing plate which concerns on this invention, and an optical member set containing the same. It is a figure for demonstrating the measuring method of the reflectance Y of the 1st optical film outer surface, and is a perspective view which shows typically the incident direction of a laser beam, and the direction of the reflected light to be measured. It is a schematic sectional drawing which shows another example of the polarizing plate which concerns on this invention, and an optical member set containing the same. It is a schematic sectional drawing which shows another example of the polarizing plate which concerns on this invention, and an optical member set containing the same. It is a schematic sectional drawing which shows an example of the touch input type image display apparatus which concerns on this invention.

<Polarizing plate and optical member set>
FIG. 1 is a schematic cross-sectional view showing an example of a polarizing plate according to the present invention and an optical member set including the polarizing plate. Like the polarizing plate 1 shown in FIG. 1, the polarizing plate according to the present invention includes a polarizer 10 and a first optical film 20 laminated on one surface thereof. The polarizing plate according to the present invention can be used as one of the members constituting the touch input type image display device. In this case, the polarizing plate is the viewing side (front side) of the image display element of the touch input type image display device. ).

The optical member set according to the present invention is a set (combination) of optical members for constructing a touch input type image display device, and includes the polarizing plate 1 and the translucent member 30 described above with reference to FIG. The optical member set 40 is constructed by the polarizing plate 1 and the translucent member 30 disposed on the first optical film 20 side (viewing side of the polarizing plate 1). This optical member set 40 is used in an air gap type touch input type image display device, that is, the translucent member 30 is arranged and fixed separately from the first optical film 20.

(1) Polarizer The polarizer 10 constituting the polarizing plate 1 absorbs linearly polarized light having a vibration plane parallel to the optical axis and transmits linearly polarized light having a vibration plane orthogonal to the optical axis. Specifically, a film in which a dichroic dye (iodine or dichroic organic dye) is adsorbed and oriented on a polyvinyl alcohol-based resin film can be suitably used.

The polyvinyl alcohol resin constituting the polarizer 10 can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group. The degree of saponification of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal and polyvinyl acetal modified with aldehydes may be used.

In this specification, “(meth) acryl” means at least one selected from acrylic and methacrylic. The same applies to cases such as “(meth) acrylate”.

The degree of polymerization of the polyvinyl alcohol resin is usually about 1000 to 10000, preferably about 1500 to 5000. Specific examples of the polyvinyl alcohol-based resin and dichroic dye include those exemplified in JP 2012-159778 A.

A film obtained by forming the polyvinyl alcohol resin is used as a raw film of the polarizer 10. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. The thickness of the raw film made of polyvinyl alcohol resin is not particularly limited, but is, for example, about 1 to 150 μm. Considering easiness of stretching, the thickness is preferably 10 μm or more.

The polarizer 10 is, for example, a step of uniaxially stretching a polyvinyl alcohol resin film as described above; a step of dyeing a polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye; It can be manufactured through a step of treating the polyvinyl alcohol resin film adsorbed with boric acid aqueous solution; a step of washing with water after the boric acid aqueous solution treatment; and a drying step. The thickness of the polarizer 10 can be about 2 to 40 μm, and preferably about 3 to 30 μm.

The polarizer 10 may be manufactured in accordance with, for example, a method described in JP2012-159778A. In the method described in the document, instead of using the raw film made of the polyvinyl alcohol resin, a polyvinyl alcohol resin layer is formed by coating the polyvinyl alcohol resin on the base film, and this is stretched. After dyeing and making a polarizer layer (polarizer 10), an optical film such as a protective film is bonded to obtain a polarizing plate.

(2) Configuration of First Optical Film The first optical film 20 can be a thermoplastic resin film (protective film) having only a function of protecting the polarizer 10, but in addition to the protective function, the polarizing plate 1 In order to impart other optical functions to the first optical film 20 and / or to impart predetermined surface characteristics to the first optical film 20, as shown in FIG. 1, the first thermoplastic resin film 21 and its It is preferable that the optical layer 22 laminated | stacked on the surface on the opposite side to the polarizer 10 is included.

The optical layer 22 is formed of fine surface irregularities such that the outer surface S (the surface opposite to the first thermoplastic resin film 21) satisfies predetermined surface characteristics described later. The optical layer 22 can have a single-layer structure or a multilayer structure, and is not particularly limited. For example, the anti-glare layer, the hard coat layer, the low refractive index layer, the antireflection layer, the antistatic layer, the antifouling layer, or these layers. Of these, a layer having two or more functions (characteristics) can be included. Since the optical layer 22 is a layer having surface irregularities, it typically includes an antiglare layer or an antiglare layer that also serves as a hard coat layer. The configuration, material, and surface unevenness of the optical layer 22 are selected and adjusted so as to satisfy predetermined surface characteristics described later.

The first thermoplastic resin film 21 is preferably made of a light-transmitting thermoplastic resin, more preferably an optically transparent thermoplastic resin, and good mechanical strength, thermal stability, and the like. It is preferable to consist of a thermoplastic resin. Examples of such resins include polyolefin resins such as chain polyolefin resins (polyethylene resins, polypropylene resins, etc.), cyclic polyolefin resins (norbornene resins, etc.); triacetyl cellulose, diacetyl cellulose, etc. Cellulosic resin (cellulose ester resin); Polyester resin such as polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate; (Meth) acrylic such as (meth) acrylic resin, (meth) acrylic ester copolymer Polyresin resin; Polycarbonate resin; Polysulfone resin; Polyethersulfone resin; Polyimide resin and the like. Among these, cellulose resins, (meth) acrylic resins, cyclic polyolefin resins, polyester resins and the like are preferably used.

The thickness of the first thermoplastic resin film 21 is usually about 5 to 200 μm, preferably 10 μm or more, and preferably 80 μm or less.

The optical layer 22 having the outer surface S composed of fine surface irregularities can be formed by, for example, applying a translucent resin on the first thermoplastic resin film 21 and curing the applied layer as necessary. . At this time, the formation of fine surface irregularities is carried out by bringing fine particles into the translucent resin, or by closely attaching a mold having an irregular surface (embossing mold) to the coating layer containing the translucent resin. It can be performed by a method of transferring the uneven surface to the coating layer.

Specific examples of the translucent resin include an active energy ray curable resin such as an ultraviolet curable resin and an electron beam curable resin, a thermosetting resin, a thermoplastic resin, and a metal alkoxide. Among these, particularly in the case of forming an antiglare layer or a hard coat layer, an active energy ray-curable resin is preferable because high hardness and scratch resistance can be imparted. When an active energy ray curable resin, a thermosetting resin, or a metal alkoxide is used, the optical layer 22 (or a layer constituting the optical layer 22) is formed by curing the resin by irradiation or heating with an active energy ray.

Specific examples of the active energy ray-curable resin include polyfunctional (meth) acrylates such as (meth) acrylic acid esters of polyhydric alcohols; terminal isocyanato group urethane prepolymers obtained by reaction of diisocyanates and polyhydric alcohols ( Polyfunctional urethane (meth) acrylates such as those obtained by reacting hydroxyalkyl esters of meth) acrylic acid are included. Besides these, polyether resins having a (meth) acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can also be active energy ray curable resins.

Examples of the thermosetting resin include a phenol resin, a urea melamine resin, an epoxy resin, an unsaturated polyester resin, and a silicone resin in addition to a thermosetting urethane resin composed of (meth) acryl polyol and an isocyanate prepolymer.

Specific examples of the thermoplastic resin include cellulose derivatives such as acetylcellulose, nitrocellulose, acetylbutylcellulose, ethylcellulose, and methylcellulose; vinyl acetate homopolymer or copolymer, vinyl chloride homopolymer or copolymer, chloride Vinyl resins such as vinylidene homopolymers or copolymers; acetal resins such as polyvinyl formal and polyvinyl butyral; (meth) acrylic resins and (meth) acrylic ester copolymers (meth) Including acrylic resin; polystyrene resin; polyamide resin; polyester resin; polycarbonate resin.

As the metal alkoxide, an alkoxysilane-based material can be used, which forms a silicon oxide-based matrix by hydrolysis or dehydration condensation. Specifically, it is tetramethoxysilane, tetraethoxysilane, or the like, and forms an inorganic or organic-inorganic composite matrix by hydrolysis or dehydration condensation to become a translucent resin.

Among these, active energy ray curable resins and thermosetting resins (both before curing) are prepared in a liquid state, and metal alkoxides are often liquid. As described above, the resin prepared in a liquid state can be used as it is as a coating liquid for forming the optical layer 22, but if necessary, it may be diluted with a solvent or the like as the coating liquid. On the other hand, a resin prepared as a solid such as a thermoplastic resin is used as a coating solution in a state dissolved in an appropriate solvent. The coating liquid containing an active energy ray curable resin, a thermosetting resin, a metal alkoxide, or a thermoplastic resin can contain an appropriate additive such as a leveling agent or a dispersant.

The optical layer 22 can contain fine particles in order to form surface irregularities as described above or to impart internal haze for the purpose of reducing glare or the like. In this case, the optical layer 22 is an antiglare layer or includes an antiglare layer. As the fine particles, translucent ones are used. Specific examples thereof include (meth) acrylic resins, melamine resins, polyethylene resins, polystyrene resins, organic silicone resins, (meth) acrylic acid ester-styrene copolymers. Organic fine particles composed of calcium carbonate, silica, aluminum oxide, barium carbonate, barium sulfate, titanium oxide, glass, etc .; organic polymer balloons; glass hollow beads. The fine particles may be used alone or in combination of two or more. The shape of the fine particles may be spherical, flat, plate-like, needle-like, indeterminate.

From the viewpoint of imparting surface irregularities and developing internal haze, the particle diameter (weight average particle diameter) of the fine particles is preferably in the range of 0.5 to 20 μm. Also, in order to sufficiently increase the expression of internal haze, the difference between the refractive index of the light-transmitting resin (active energy ray-curable resin, thermosetting resin, and cured product in the case of metal alkoxide) and the refractive index of the fine particles The (absolute value) is preferably in the range of 0.04 to 0.15.

The content of the fine particles is usually 3 to 60 parts by weight, preferably 5 to 50 parts by weight with respect to 100 parts by weight of the translucent resin. If the content of fine particles is less than 3 parts by weight, it is difficult to obtain sufficient internal haze for reducing glare. On the other hand, when the content exceeds 60 parts by weight, the transparency of the obtained first optical film 20 may be impaired, and when the polarizing plate is applied to an image display device, light scattering is too strong. For example, in black display, the light leaking obliquely with respect to the front direction of the image display apparatus may be reduced in contrast because the optical layer 22 strongly scatters in the front direction.

The low refractive index layer that can be included in the optical layer 22 is a resin material such as an ultraviolet curable (meth) acrylic resin; a hybrid material in which inorganic fine particles such as colloidal silica are dispersed in a resin; a sol containing alkoxysilane; It can be formed from a gel material or the like. The refractive index of the low refractive index layer can range from 1.30 to 1.45. The low refractive index layer may be formed by coating a polymer that has been polymerized, or may be formed by coating in the state of a monomer or oligomer that is a precursor, followed by polymerization and curing.

The sol-gel material preferably contains a compound having a fluorine atom in the molecule, and a typical example thereof is polyfluoroalkylalkoxysilane. For example, the polyfluoroalkylalkoxysilane is represented by the following formula:
CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OR) ₃
It can be a compound shown by these. Here, R represents an alkyl group having 1 to 5 carbon atoms, and n represents an integer of 0 to 12. Of these, compounds in which n in the above formula is 2 to 6 are preferred.

The low refractive index layer can also be formed by curing a curable fluorine-containing compound such as a fluorine-containing polymer having a crosslinkable functional group. The fluorine-containing polymer having a crosslinkable functional group can be obtained by 1) copolymerizing a fluorine-containing monomer and a monomer having a crosslinkable functional group, or 2) copolymerizing a fluorine-containing monomer and a monomer having a functional group. Then, it can be produced by a method of adding a compound having a crosslinkable functional group to the functional group in the polymer.

Examples of the fluorine-containing monomer include fluoroolefins such as fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole; (meth) acrylic acid Partially or fully fluorinated alkyl ester derivatives of the above; fully or partially fluorinated vinyl ethers of (meth) acrylic acid.

Examples of the monomer having a crosslinkable functional group and the compound having a crosslinkable functional group include a monomer having a glycidyl group such as glycidyl (meth) acrylate; a monomer having a carboxyl group such as (meth) acrylic acid; Examples thereof include monomers having a hydroxyl group such as alkyl (meth) acrylate; monomers having an alkenyl group such as allyl (meth) acrylate; monomers having an amino group; monomers having a sulfonic acid group.

The low refractive index layer can contain low refractive index inorganic fine particles made of silica, alumina, titania, zirconia, magnesium fluoride or the like. Among these, silica hollow fine particles are preferably used. The average particle diameter of the fine particles is preferably in the range of 5 to 2000 nm, more preferably in the range of 20 to 100 nm.

The polarizing plate 1 can be obtained by bonding the first optical film 20 to one surface of the polarizer 10. Bonding with the polarizer 10 and the 1st optical film 20 can be performed using an adhesive agent or an adhesive. As the adhesive, a water-based adhesive containing a polyvinyl alcohol resin or a urethane resin as a main component, or a photocurable adhesive containing a photocurable resin such as an ultraviolet curable resin (epoxy resin or the like) is used. it can. As the pressure-sensitive adhesive, those having a base polymer of (meth) acrylic polymer, silicone polymer, polyester, polyurethane, polyether or the like can be used. Prior to the bonding, the bonding surface of the polarizer 10 and / or the first optical film 20 may be subjected to an easy adhesion process such as a saponification process, a corona process, a primer process, and an anchor coating process.

(3) Surface characteristics of the first optical film In the polarizing plate 1 of the present invention, the outer surface S of the first optical film 20 has a cross-sectional curve kurtosis Pku of 3.0 or more and a reflectance Y of 4.0%. It is as follows. By imparting such surface characteristics to the outer surface S composed of fine surface irregularities, it is possible to effectively suppress the occurrence of Newton rings when the screen is pressed with fingers or the like.

As in the above-mentioned

Patent Documents

1 and 2, in the conventional study for suppressing Newton ring, the relationship between the surface irregularity shape directed to the air gap side and the occurrence of Newton ring is represented by the arithmetic average roughness Ra of the surface irregularity. It was evaluated with. However, as a result of the study by the present inventor, it is possible to more accurately evaluate the relationship between the surface irregularity shape and the occurrence of Newton rings by using Pku, which is an index representing the kurtosis of the convex portion, rather than the arithmetic average roughness Ra. Assuming that the reflectance Y is 4.0 or less, it has become clear that the occurrence of Newton rings can be effectively suppressed by setting Pku to 3.0 or more. In addition, even if the arithmetic average roughness Ra of the surface irregularities is the same, Pku can be significantly different, and it has been clarified by the present inventors that the arithmetic average roughness Ra and Pku do not necessarily correlate. .

In addition, the present inventor not only adjusts Pku to a predetermined range but also reflects the reflectance Y not only on the outer surface S but also the reflectance Y greatly affects the occurrence of Newton rings. It has been found that the rate Y must also be adjusted to a predetermined range.

Cross-sectional curve kurtosis Pku corresponds to JIS B 0601: 2013 “Product Geometrical Specification (GPS) -Surface Properties: Contour Curve Method—Terminology, Definitions and Surface Property Parameters” (ISO 4287: 1997, Amd. 1: 2009) )) Defined in 4.2.4, and is defined by the following equation.

In the formula, Z (x) is the height of the cross-sectional curve at an arbitrary position x, and Lp is the reference length (equivalent to the evaluation length) of the cross-sectional curve. Pq is the root mean square height of the cross-sectional curve, and is defined as follows in 4.2.2 of JIS B 0601: 2013.

That is, Pku is the mean square of Z (x) at the reference length Lp made dimensionless by the square of the root mean square height Pq of the cross-sectional curve. Pku is a parameter indicating the degree of sharpness (sharpness) of the probability density function of the cross-section curve, and is called “spiral degree” in statistical terms.

Pku can be measured using a commercially available three-dimensional shape measuring device, a roughness meter, or the like. In Examples described later, measurement was performed using a three-dimensional microscope “PLμ 2300” manufactured by SENSOFAR. This apparatus is designed to automatically calculate specified parameters for the measurement sample.

The reflectance Y means a visibility correction reflectance, and specifically, a spectral reflectance in a wavelength range of 350 to 900 nm at a reflection angle of 12 ° when light is incident at an incident angle of 12 °. This means the reflectance obtained by correcting the visibility (ie, the regular reflectance at an incident angle of 12 °) with a 2 degree visual field (C light source) of JIS Z 8701. Referring to FIG. 2, the measurement method of the reflectance Y will be specifically described. The reflectance Y is inclined by 12 ° with respect to the normal 200 direction of the first optical film 20 on the outer surface S side of the first optical film 20. Reflecting light incident from a direction and reflected in a direction inclined at an angle of 12 ° to the opposite side of the incident light 201 in the plane 203 including the direction of the incident light 201 and the normal 200. The spectral reflectance of the light 204 (reflected light in the regular reflection direction) is measured. Furthermore, from the obtained spectral reflectance, the reflectance Y can be obtained by correcting the visibility with a 2-degree field (C light source) of JIS Z 8701.

The reflected light Y can be measured using a spectrophotometer or the like. In measuring the reflectance Y, the possibility of reflection from the back surface of the first optical film 20 affecting the measurement value is eliminated, and in addition, the first optical film 20 is optically transparent to prevent warping. The first optical film 20 bonded to a black plate (black acrylic plate or the like) on the first thermoplastic resin film 21 side is used as a measurement sample.

It can be said that the higher the Pku and the lower the reflectance Y, the more advantageous the suppression of the Newton ring. For example, when the Pku is sufficiently high, even if the reflectance Y is relatively high in the range of 4.0 or less, the Newton ring When the reflectance Y is sufficiently low, Newton's ring tends to be sufficiently suppressed even if Pku is relatively low in the range of 3.0 or more. For example, when Pku is 4.5 or more, Newton's ring can be sufficiently suppressed even if the reflectance Y is 2.0 or more, further 2.5 or more, and even 3.0 or more. Further, when the reflectance Y is 2.0 or less, Newton rings can be sufficiently suppressed even if Pku is 5.0 or less, further 4.0 or less, and even 3.5 or less. When Pku is relatively low as 3.0 to 5.0, the reflectance Y is preferably 3.0 or less, more preferably 2.5 or less, and further preferably 2.0 or less (particularly 1. 5 or less). Further, when the reflectance Y is relatively high as 3.0 to 4.0, Pku is preferably 3.1 or more, more preferably 3.5 or more, and further preferably 4.0 or more. .

The outer surface S of the first optical film 20 preferably has an arithmetic average roughness Ra of 100 nm or less. The arithmetic average roughness Ra is a parameter defined in 4.2.1 of JIS B 0601: 2013, and means an average value of absolute values of the height Z (x) in the reference length. By controlling the arithmetic average roughness Ra to 100 nm or less, the Newton ring suppression effect may be enhanced. The arithmetic average roughness Ra of the outer surface S of the first optical film 20 is usually 30 nm or more.

The adjustment of Pku can be performed according to a known method in the field of an antiglare film used for preventing reflection of external light and glare due to surface unevenness. For example, when the optical layer 22 is formed using a coating liquid containing fine particles, the design of the coating liquid, that is, the particle diameter of the fine particles, a translucent resin (for example, active energy ray curable) that forms the optical layer 22 is used. There are methods for adjusting the amount of fine particles added to the resin), the film thickness of the optical layer 22, the solvent of the coating solution, the drying conditions of the coating layer, and the like. In addition, when the surface unevenness shape is transferred by pressing a mold with surface irregularities (embossed mold) against the coating layer of the translucent resin, a mold with a predetermined surface shape is used as the mold. do it.

Further, as a method for adjusting the reflectance Y to a predetermined range, a low refractive index layer may be provided on the outermost surface of the optical layer 22 or a fine uneven structure may be provided on the surface.

(4) Translucent member In the optical member set 40, the translucent member 30 disposed on the first optical film 20 side (the viewing side of the polarizing plate 1) of the polarizing plate 1 is a translucent plate, sheet, or the like. A protective plate (front plate) disposed on the outermost surface of the image display device by providing the image display element with a function of the touch input element, in addition to being a touch input element (touch panel) itself. ) Can be a member that only plays a role. The translucent member 30 can be a glass plate or various thermoplastic resin films having translucency (preferably optically transparent). The content described about the 1st thermoplastic resin film 21 is quoted about the specific example of a thermoplastic resin.

As will be described later, when the touch input type image display device is a resistive film type, a transparent conductive layer is formed on the outermost surface on the first optical film 20 (air gap) side of the translucent member 30 that is a touch input element. May be formed. Since the translucent member 30 as a touch input element used in the resistive film method is preferably flexible, it is often composed of a thermoplastic resin film. On the other hand, in the translucent member 30 used for the electrostatic capacity method, flexibility is often not required, and either a glass plate or a thermoplastic resin film can be used.

(5) Modified Example of Polarizing Plate and Optical Member Set FIG. 3 is a schematic cross-sectional view showing another example of the polarizing plate according to the present invention and an optical member set including the polarizing plate. Like the polarizing plate 2 shown in FIG. 3, the polarizing plate according to the present invention is on the surface of the polarizer 10 opposite to the first optical film 20 in addition to the polarizer 10 and the first optical film 20. A second optical film 25 may be further included. The second optical film 25 is a film disposed on the image display element side in the image display device. The optical member set 41 shown in FIG. 3 includes the polarizing plate 2 and the above-described translucent member 30, and is disposed on the polarizing plate 2 and the first optical film 20 side (viewing side of the polarizing plate 2). It is used for an air gap type touch input type image display device constructed with the translucent member 30.

The second optical film 25 may be a film made of a thermoplastic resin film (second thermoplastic resin film) or a film including the same. The content described about the 1st thermoplastic resin film 21 is quoted about the specific example of the thermoplastic resin which comprises a 2nd thermoplastic resin film. Among these, cellulose resins, (meth) acrylic resins, cyclic polyolefin resins, and the like are preferably used. The thickness of the second optical film 25 is usually about 5 to 200 μm, preferably 10 μm or more, and preferably 80 μm or less.

The second optical film 25 may be a simple protective film for protecting the polarizer 10, or may be a protective film having both optical functions such as a retardation film (optical compensation film) and a brightness enhancement film. You can also. The retardation film may be, for example, a liquid crystal compound formed on a film obtained by uniaxially or biaxially stretching the second thermoplastic resin film (cyclic polyolefin resin film or the like) or the second thermoplastic resin film (cellulose resin film or the like). Can be applied and oriented film. Further, the second optical film 25 may be a birefringent film in which the refractive index in the thickness direction of the film is controlled by applying a shrinkage force and / or stretching force under adhesion with the heat-shrinkable film. Moreover, the 2nd optical film 25 may be a laminated body of the 2nd thermoplastic resin film which is a protective film, and the optical compensation film laminated | stacked on it.

Following formula:
R ₀ = (n _x −n _y ) × d
R _th = [{(n _x + _ny ) / 2} −n _z ] × d
If the image display element is a liquid crystal cell, for example, the in-plane retardation value R ₀ and the thickness direction retardation value R _th of the retardation film defined in (1) are appropriately adjusted according to the type of the liquid crystal cell. N _x is the in-plane slow axis direction of the refractive index in the above formulas, n _y is a refractive index in the in-plane fast axis direction (perpendicular to the plane slow axis direction), n _z is the refractive index in the thickness direction, d is the thickness of the film. When the image display element is an organic EL display element, the retardation film can be, for example, a 1 / 4λ plate.

Bonding of the second optical film 25 and the polarizer 10 can also be performed using an adhesive such as a water-based adhesive or a photocurable adhesive, or a pressure-sensitive adhesive. Prior to bonding, the above-described easy adhesion treatment may be performed on the bonding surface of the polarizer 10 and / or the second optical film 25.

FIG. 4 is a schematic cross-sectional view showing another example of the polarizing plate according to the present invention and an optical member set including the polarizing plate. As shown in FIG. 4, the polarizing plate and the translucent member may have a transparent conductive layer. The optical member set 42 including the polarizing plate 3 and the translucent member 30 shown in FIG. 4 can be used for a resistive film system, and the first optical film 20 (air) in the translucent member 30 as a touch input element. A transparent conductive layer 31 is formed on the outermost surface on the gap) side, and a transparent conductive layer 23 is also formed on the outer surface S of the first optical film 20. The transparent

conductive layers

23 and 31 serving as electrodes play a role for detecting the position when the translucent member 30 side is pressed with a finger or the like so that they come into contact with each other at that position. The transparent

conductive layers

23 and 31 can be made of ITO (indium tin oxide) or the like well known in the resistive film system.

The polarizing plate 3 shown in FIG. 4 can further include a second optical film 25 laminated on the surface opposite to the first optical film 20, similarly to the polarizing plate 2 shown in FIG. 3.

<The manufacturing method of a 1st optical film>
Here, the manufacturing method of the 1st optical film 20 is demonstrated more concretely. The 1st optical film 20 which has the outer surface S which consists of surface asperity coats the coating liquid containing translucent resin and microparticles | fine-particles on the 1st thermoplastic resin film 21, and dries a coating layer as needed. (If a solvent is included), then, if necessary, the coating layer is irradiated with active energy rays (when an active energy ray-curable resin is used) or heated (when a thermosetting resin or metal alkoxide is used). Or by applying a coating liquid containing a light-transmitting resin (which may contain fine particles), and forming an uneven surface on the coating layer. It can be manufactured by a method in which a mold having an embossing (embossing mold) is brought into close contact, and the uneven surface is transferred to a coating layer. In order to finely adjust the surface irregularities and control the reflectance Y, another layer (for example, a low refractive index layer) can be further laminated on the layer obtained by the above method.

Among the above methods, a method preferably used for imparting surface irregularities is a method using an embossing mold, and this method includes the following steps:
(A) A step of applying a coating liquid containing a translucent resin on the first thermoplastic resin film 21, and (B) an uneven surface of an embossing type (transfer type) on the surface of the coating layer. A transfer step.

The coating liquid used in the above step (A) contains a translucent resin, and if necessary, contains other components such as translucent fine particles and a solvent. When an ultraviolet curable resin is used as the translucent resin, the coating solution further contains a photopolymerization initiator (radical polymerization initiator). Examples of the photopolymerization initiator include acetophenone photopolymerization initiator, benzoin photopolymerization initiator, benzophenone photopolymerization initiator, thioxanthone photopolymerization initiator, triazine photopolymerization initiator, and oxadiazole photopolymerization initiator. An initiator or the like is used. Also, for example, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 10- Butyl-2-chloroacridone, 2-ethylanthraquinone, benzyl, 9,10-phenanthrenequinone, camphorquinone, methyl phenylglyoxylate, titanocene compounds and the like can also be used as a photopolymerization initiator. The amount of the photopolymerization initiator used is usually 0.5 to 20 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of the ultraviolet curable resin contained in the coating liquid.

The application of the coating liquid onto the first thermoplastic resin film 21 is performed by, for example, a gravure coating method, a micro gravure coating method, a rod coating method, a knife coating method, an air knife coating method, a kiss coating method, a die coating method, or the like. be able to.

Various surface treatments may be applied to the coated surface of the first thermoplastic resin film 21 for the purpose of improving the coating properties of the coating liquid or improving the adhesion with the resulting coating layer. The surface treatment can be a corona discharge treatment, a glow discharge treatment, an acid surface treatment, an alkali surface treatment, an ultraviolet irradiation treatment or the like. Further, another layer such as a primer layer may be formed on the first thermoplastic resin film 21 and a coating solution may be applied thereon.

In the above step (B), an embossed uneven surface is brought into close contact with the surface of the coating layer, and the uneven surface is transferred. By transferring the embossed uneven surface to the surface of the coating layer in this manner, the optical layer 22 (or a layer constituting the same) having a desired surface shape can be formed.

When an active energy ray curable resin, a thermosetting resin or a metal alkoxide is used as the translucent resin, irradiation with active energy rays (active energy) is performed with an embossed uneven surface in close contact with the surface of the coating layer. The coating layer is cured by heating (when using a linear curable resin) or heating (when using a thermosetting resin or metal alkoxide). The active energy ray can be appropriately selected from an electron beam, an ultraviolet ray, a near ultraviolet ray, a visible light, a near infrared ray, an infrared ray, an X-ray and the like according to the type of resin contained in the coating liquid. Among these, ultraviolet rays or electron beams are preferable, and ultraviolet rays are preferably used because they are easy to handle and high energy is obtained.

When ultraviolet rays are employed, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, or the like can be used. Further, an ArF excimer laser, a KrF excimer laser, an excimer lamp, synchrotron radiation, or the like can also be used. Among these, mercury lamps, xenon lamps, or metal halide lamps including ultra-high pressure, high pressure, medium pressure and low pressure are preferably used.

As the electron beam, 50 to 1000 keV emitted from various electron beam accelerators such as a cockroft Walton type, a bandegraph type, a resonance transformation type, an insulating core transformation type, a linear type, a dynamitron type, or a high frequency type, preferably 100 Mention may be made of electron beams having an energy of ˜300 keV.

<Embossed production method>
The embossing mold used for imparting surface irregularities to the optical layer 22 has a surface irregularity shape corresponding to the desired surface irregularity shape of the optical layer 22.

The surface uneven pattern in the embossed pattern may be a regular pattern, a random pattern, or a pseudo-random pattern in which one or more random patterns of a specific size are spread. However, from the viewpoint of preventing the reflected image from becoming iridescent due to interference of reflected light caused by the surface shape, it is preferably a random pattern or a pseudo-random pattern.

The outer shape of the embossed mold is not particularly limited, and may be a flat plate shape or a cylindrical or cylindrical roll, but from the viewpoint of continuous productivity of the first optical film 20. A columnar or cylindrical mold, that is, an embossing roll is preferable. In this case, a predetermined surface shape is formed on the side surface of the columnar or cylindrical mold.

The substrate constituting the embossing mold is not particularly limited, and can be appropriately selected from, for example, metal, glass, carbon, resin, or a composite thereof, but metal is preferable from the viewpoint of workability. The metal material suitably used for the embossing mold is aluminum, iron, or an alloy mainly composed of aluminum or iron, particularly from the viewpoint of cost.

As a method for obtaining an embossing mold, for example, a base material is polished, sandblasted, and then subjected to electroless nickel plating (Japanese Patent Laid-Open No. 2006-53371); the base material is subjected to copper plating or nickel plating. Then, polishing, then sandblasting, and further chromium plating (Japanese Patent Laid-Open No. 2007-187852); copper plating or nickel plating, polishing, then sandblasting, and further etching step Alternatively, a method of performing chromium plating after passing through a copper plating step (Japanese Patent Laid-Open No. 2007-237541); applying copper plating or nickel plating to the surface of the substrate, polishing, and then applying a photosensitive resin film on the polished surface Forming, exposing the pattern on the photosensitive resin film, then developing, and using the developed photosensitive resin film as a mask Etching treatment is performed, the photosensitive resin film is peeled off, and further the etching treatment is performed to make the concavo-convex surface dull, and then the formed concavo-convex surface is subjected to chromium plating (JP 2010-76385 A and JP 2012-68474 gazette); the method (international publication 2007/077892 pamphlet) etc. which cut the base material used as a casting_mold | template with a cutting tool using machine tools, such as a lathe.

Embossed surface irregularities consisting of random patterns or pseudo-random patterns include, for example, FM screen method, DLDS (Dynamic Low-Discontinuity Sequence) method, method using block copolymer microphase separation pattern, bandpass filter method A random pattern created by the above method can be formed by exposing the photosensitive resin film, developing it, and performing an etching process using the developed photosensitive resin film as a mask.

<Touch input image display device>
In the touch input type image display device according to the present invention, the polarizing plate according to the present invention is disposed on the viewing side of the image display element, and the first optical film side of the polarizing plate is separated from the first optical film. An optical member is arranged. The image display element may be a non-self light emitting element such as a liquid crystal cell, or may be a self light emitting element such as an organic EL display element.

An example of a touch input type image display device using the liquid crystal cell 50 as an image display element is shown in FIG. In this example, the optical member set 40 shown in FIG. 1 is applied. However, the present invention is not limited to this, and any optical member set according to the present invention may be used. The operation method of the touch input type image display apparatus may be any method, but typical examples are a resistive film method and a capacitance method. The liquid crystal cell 50 has a liquid crystal layer sandwiched between two transparent substrates, controls the alignment state of the liquid crystal layer by applying a voltage, and enables display. A liquid crystal cell known in the field of liquid crystal display is adopted. be able to.

When the touch input type image display device is a liquid crystal display device including the liquid crystal cell 50, as shown in FIG. 5, a back side polarizing plate 60 is disposed on the back side of the liquid crystal cell 50, and further on the back side thereof. A backlight 80 for supplying display light is disposed. The polarizing plate is usually bonded to the liquid crystal cell 50 via the pressure-sensitive adhesive layers 70 and 71.

On the other hand, when an organic EL display element is employed as the image display element, the organic EL display element is a self-luminous type, and therefore, instead of the liquid crystal cell 50, the adhesive layer 71, the back side polarizing plate 60, and the backlight 80 in FIG. In addition, this organic EL display element may be disposed. The organic EL display element includes a light emitter including an organic light emitting material sandwiched between a pair of electrodes, and a well-known one in this field can also be employed.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified.

<Example 1>
(A) Manufacture of optical film (A1) Manufacture of mold for optical film (emboss mold) According to the method described in Example 1 (B) of JP 2012-68474 A, etching for forming irregularities By changing the amount, a mold for imparting an uneven shape to the optical film was produced. That is, first, an aluminum roll having a diameter of 200 mm (A5056 according to JIS) with copper ballad plating applied thereto was prepared. The copper ballad plating was composed of a copper plating layer / a thin silver plating layer / a surface copper plating layer, and the thickness of the entire plating layer was about 200 μm. The copper plating surface was mirror-polished, a positive photosensitive resin was applied to the polished copper plating surface, and dried to form a photosensitive resin film. Next, the photosensitive resin film was exposed to laser light so that a predetermined pattern (pattern shown in FIG. 16 of the same publication) was repeated, and then developed. The laser light exposure and development were performed using “Laser Stream FX” manufactured by Sink Laboratories.

After the development, a first etching process was performed with a cupric chloride aqueous solution. Next, the photosensitive resin film was removed from the roll after the first etching treatment, and a second etching treatment was again performed with a cupric chloride aqueous solution. At this time, in order to adjust the kurtosis Pku of the cross-sectional curve of the optical film obtained by the subsequent processing to a predetermined value, the first etching processing amount (thickness cut by etching) is 4 μm, and the second etching processing amount (also the same) The thickness (thickened by etching) was set to 12 μm. Thereafter, chrome plating was performed. The thickness of the chromium plating was set to 4 μm. Thus, a mold roll having fine irregularities on the surface was produced.

(A2) Preparation of UV curable resin composition The following were prepared as raw materials for the UV curable resin composition.
UV curable resin: a mixture of 60 parts of pentaerythritol triacrylate and 40 parts of polyfunctional urethanized acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate).
Photopolymerization initiator: “Lucirin TPO” (chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) sold by BASF.

A UV curable resin composition for forming a coating layer was prepared by mixing 5 parts of the photopolymerization initiator and 150 parts of ethyl acetate as a diluent solvent with 100 parts of the UV curable resin.

(A3) Production of optical film The ultraviolet curable resin composition prepared above was coated on a thermoplastic resin film made of triacetylcellulose with a die coater so that the film thickness after drying was 5 μm, and a thermoplastic resin was obtained. A laminate comprising a film and a coating layer of an ultraviolet curable resin composition was obtained. After drying this laminated body in a drying furnace, it was pressed and adhered to the mold roll produced in (A1) above with a nip roll so that the coating layer side was in contact with the mold. In this state, ultraviolet rays were irradiated from the thermoplastic resin film side so that the maximum illuminance was 700 mW / cm ² and the integrated light amount was 300 mJ / cm ² , thereby curing the ultraviolet curable resin composition. Then, the laminated body was peeled from the mold roll to form a resin layer having irregularities on the surface.

(A4) Formation of Low Refractive Index Layer Isopropyl alcohol and 0.1N hydrochloric acid are added to a 95: 5 (molar ratio) mixture of tetraethoxysilane and 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane to cause hydrolysis. Thus, a solution containing an organosilicon compound polymer composed of an oligomer was obtained. Low refractive index silica hollow fine particles are mixed into this solution and isopropyl alcohol is added to obtain a coating solution for forming a low refractive index layer containing 2% by weight of an organosilicon compound and 2% by weight of low refractive index silica hollow fine particles. It was. The obtained coating solution for forming a low refractive index layer is coated on the uneven surface of the optical film obtained above with a wire bar coater and dried in a dryer set at 120 ° C. for 1 minute to reduce the refractive index. An index layer was formed to obtain an optical film. The resulting low refractive index layer had a thickness of 102 nm and a refractive index of 1.37.

(B) Measurement of surface shape of optical film Using a three-dimensional microscope “PLμ 2300” manufactured by SENSOFAR, the magnification of the objective lens is 20 times, and the surface shape of the optical film obtained above in the confocal mode ( The cross-sectional curve kurtosis Pku) was determined. The measurement area was 637 μm × 477 μm. In order to prevent warping of the optical film sample, an optically transparent adhesive is used, and the sample is bonded to the glass substrate on the surface opposite to the uneven surface (the uneven surface becomes the surface). Measurements were made. Pku of the uneven surface of the obtained optical film was 3.2.

(C) Measurement of reflectance Y (reflectance Y value) of optical film In accordance with the measurement method described above, the spectrophotometer ("UV2450" manufactured by Shimadzu Corporation) was integrated with an integrating sphere ("BIS-" manufactured by Shimadzu Corporation). 3100 ") was used to measure the reflectance Y value. In order to prevent reflection from the back side of the optical film sample and to prevent warping of the sample, an optically transparent adhesive is used to prepare a sample on the surface opposite to the uneven surface (the uneven surface becomes the surface). Measurement was performed after bonding to a black acrylic plate (“SUMIPEX” manufactured by Sumitomo Chemical Co., Ltd.). The reflectance Y of the concavo-convex surface of the obtained optical film was 1.0%.

(D) Production of Polarizer A polyvinyl alcohol film having an average polymerization degree of about 2,400 and a saponification degree of 99.9 mol% or more and a thickness of 75 μm was immersed in pure water at 30 ° C., and then iodine / potassium iodide / It dye | stained by immersing in the aqueous solution whose water weight ratio is 0.02 / 2/100 at 30 degreeC. Then, it was immersed in an aqueous solution having a potassium iodide / boric acid / water weight ratio of 12/5/100 at 56.5 ° C. to carry out a crosslinking treatment. Subsequently, after washing with pure water at 8 ° C., drying was performed at 65 ° C. to obtain a polarizer in which iodine was adsorbed and oriented on polyvinyl alcohol. Stretching was mainly performed in the steps of iodine staining and boric acid crosslinking treatment, and the total stretching ratio was 5.3 times.

(E) Preparation of adhesive To 100 parts of water, 1.8 parts of carboxyl group-modified polyvinyl alcohol “Kuraray Poval KL318” (modification degree 2 mol%) sold by Kuraray Co., Ltd. was dissolved. To this, 1.5 parts of “Smilease Resin 650” (aqueous solution with a solid content of 30%) sold by Taoka Chemical Industry Co., Ltd., which is a water-soluble polyamide epoxy resin, is added and dissolved to obtain a polyvinyl alcohol adhesive. Was prepared.

(F) Production of Polarizing Plate After saponifying the surface of the thermoplastic resin film opposite to the surface on which the optical layer having the irregularities of the optical film produced in (A4) above was formed, The polyvinyl alcohol adhesive prepared in E) was applied with a 10 μm bar coater, and the polarizer prepared in (D) above was bonded thereon. Further, as a protective film to be bonded to the other surface of the polarizer, a 40 μm thick triacetyl cellulose film (“KC4UE” sold by Konica Minolta Advanced Layer Co., Ltd.), in-plane retardation value R ₀ = 0. 7 nm, thickness direction retardation R _th = −0.1 nm) was prepared. After the saponification treatment is applied to this protective film, the polyvinyl alcohol adhesive prepared in (E) above is applied to the saponification treated surface with a 10 μm bar coater, and the coated surface is coated with the optical film of the upper polarizer. It bonded on the surface on the opposite side to the surface where the film was bonded. Thereafter, it was dried at 80 ° C. for 5 minutes and further cured at room temperature for 1 day. Thus, a polarizing plate having a layer structure of optical film / polarizer / triacetyl cellulose film was produced.

(G) Evaluation of Newton's ring A 4 mm thick acrylic plate is provided on the optical film uneven surface side of the polarizing plate produced in (F) above, and the air gap between the acrylic plate and the polarizing plate surface is 0.3 mm. It adjusted and arranged so that it might become. The acrylic board was pushed with a load of 700 g to observe whether Newton rings were generated, and evaluated according to the following evaluation criteria.

A: Newton rings are not observed,
B: Newton rings are slightly observed, but at a level where there is no problem with visual recognition.
C: Newton rings are observed remarkably.

<Example 2>
An optical film was obtained in the same manner as in Example 1 except that the first etching treatment amount of the optical film mold was 5.0 μm and the thickness of the low refractive index layer was 68 nm. The surface properties of this film were measured by the same method as in Example 1. As a result, Pku was 4.9 and reflectance Y was 2.0%. A polarizing plate was produced in the same manner as in Example 1 except that this film was used as an optical film, and Newton rings were evaluated.

<Example 3>
An optical film was obtained in the same manner as in Example 1 except that the first etching treatment amount of the optical film mold was 7.0 μm and the low refractive index layer was not provided. When the surface properties of this film were measured by the same method as in Example 1, Pku was 7.9 and reflectance Y was 3.0%. A polarizing plate was produced in the same manner as in Example 1 except that this film was used as an optical film, and Newton rings were evaluated.

<Example 4>
An optical film was obtained in the same manner as in Example 1 except that the low refractive index layer was not provided. When the surface characteristics of this film were measured by the same method as in Example 1, Pku was 3.2 and reflectance Y was 3.4%. A polarizing plate was produced in the same manner as in Example 1 except that this film was used as an optical film, and Newton rings were evaluated.

<Example 5>
An optical film was obtained in the same manner as in Example 1 except that the thickness of the low refractive index layer was 80 nm. The surface properties of this film were measured by the same method as in Example 1. As a result, Pku was 3.2 and reflectance Y was 1.8%. A polarizing plate was produced in the same manner as in Example 1 except that this film was used as an optical film, and Newton rings were evaluated.

<Comparative Example 1>
The surface treatment film “NC-1B” sold by Nippon Paper Chemicals Co., Ltd. was used as the optical film. The surface properties of this film were measured by the same method as in Example 1. As a result, Pku was 3.3 and reflectance Y was 4.1%. A polarizing plate was produced in the same manner as in Example 1 except that this film was used as an optical film, and Newton rings were evaluated.

<Comparative example 2>
A surface-treated film “40CHC” sold by Toppan Printing Co., Ltd. was used as an optical film. The surface properties of this film were measured by the same method as in Example 1. As a result, Pku was 2.2 and reflectance Y was 4.2%. A polarizing plate was produced in the same manner as in Example 1 except that this film was used as an optical film, and Newton rings were evaluated.

<Comparative Example 3>
A surface-treated film “40KSPLR” sold by Toppan Printing Co., Ltd. was used as an optical film. The surface properties of this film were measured by the same method as in Example 1. As a result, Pku was 2.6 and reflectance Y was 1.0%. A polarizing plate was produced in the same manner as in Example 1 except that this film was used as an optical film, and Newton rings were evaluated.

The evaluation results of Newton rings performed in Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 1 together with the surface characteristics of the optical film used.

1, 2, 3 Polarizing plate, 10 Polarizer, 20 First optical film, 21 First thermoplastic resin film, 22 Optical layer, 23 Transparent conductive layer, 25 Second optical film, 30 Translucent member, 31 Transparent conductive Layer, 40, 41, 42 optical member set, 50 liquid crystal cell, 60 back side polarizing plate, 70, 71 adhesive layer, 80 backlight, S outer surface of the first optical film, 200 normal line of the first optical film, 201 Incident light, 203, a plane including the incident light direction and the normal line of the first optical film, and 204, reflected light reflected in the regular reflection direction.

Claims

Including a polarizer and a first optical film laminated on one surface thereof,
The surface of the first optical film opposite to the polarizer has a cross-sectional curve kurtosis Pku of 3.0 or more, and a reflectance at a reflection angle of 12 ° when light is incident at an incident angle of 12 °. The polarizing plate whose Y is 4.0% or less.
The polarizing plate according to claim 1, wherein the first optical film includes a first thermoplastic resin film and an optical layer laminated on a surface opposite to the polarizer.
The polarizing plate according to claim 2, wherein the first thermoplastic resin film is made of a cellulose resin, a (meth) acrylic resin, a cyclic polyolefin resin, or a polyester resin.
The polarizing plate according to any one of claims 1 to 3, further comprising a second optical film laminated on a surface of the polarizer opposite to the first optical film.
The polarizing plate according to claim 4, wherein the second optical film includes a second thermoplastic resin film made of a cellulose resin, a (meth) acrylic resin, or a cyclic polyolefin resin.
The polarizing plate according to claim 4 or 5, wherein the second optical film is a retardation film.
A polarizing plate according to any one of claims 1 to 6,
A translucent member to be disposed on the first optical film side in the polarizing plate;
An optical member set for a touch input type image display device.
An image display element;
The polarizing plate according to any one of claims 1 to 6, which is disposed on the viewing side of the image display element,
On the side of the first optical film in the polarizing plate, a translucent member disposed apart from the first optical film,
A touch input type image display device.
The touch input type image display device according to claim 8, wherein the translucent member is a touch input element.