TW202027968A - Polarizing plate and display device - Google Patents

Abstract

An object of the present invention is to provide a polarizing plate is which the transmittance in the central portion of the plane does not easily decrease even when being placed in a high-temperature environment and the degree of polarization does not easily decrease even when being placed in a high-temperature and high-humidity environment.

The polarizing plate comprises a polarizer, a first optical film laminated on one surface of the polarizer, a first adhesive layer laminated on the other surface of the polarizer, and a second adhesive layer disposed on the side opposite to the polarizer side of the first adhesive layer; wherein the moisture permeability of the first optical film is 100 g/m² ． 24 hr. or less, the moisture permeability of the first adhesive layer is 500 g/m² ． 24 hr. or more, and the moisture permeability of the second adhesive layer is 100 g/m² ． 24 hr. or less.

Description

Polarizing plate and display device

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

Polarizing plates are bonded between image display elements such as liquid crystal cells and organic EL elements and transparent plates such as front panels and touch panels via an adhesive layer, and are used as various image display devices such as liquid crystal display devices and organic EL display devices. . In recent years, such video display devices have been used as mobile devices such as mobile phones and tablet terminals, but also as vehicle video display devices such as navigation devices and rear view monitors. With this situation, the polarizing plate is required to have durability in a harsher environment than the conventional one (Patent Document 1).

Patent Document 1 describes a laminate in which glass plates are laminated on both sides of a polarizing plate with an adhesive interposed therebetween, and the amount of water per unit area of the polarizing plate and the saturated water supply amount of the transparent protective film constituting the polarizing plate are described as Below the established value. Patent Document 1 discloses that even if the laminate is placed in a high-temperature environment (temperature of 95°C), the transmittance of the in-plane center portion of the polarizing plate is not easily reduced.

[Prior Technical Literature]

[Patent Literature]

[Patent Document 1] JP 2014-102353 A

The polarizing plate described in Patent Document 1 has an effect of preventing a decrease in the transmittance of the in-plane center portion of the polarizing plate in a high-temperature environment. However, its effect is not necessarily sufficient. Furthermore, the polarizing plate described in Patent Document 1 has a problem that the degree of polarization is likely to decrease in a high temperature and high humidity environment.

The object of the present invention is to provide a polarizing plate whose transmittance at the inner center part is not easily reduced even if placed under a high temperature environment, and the degree of polarization is not easily reduced even if placed under a high temperature and high humidity environment.

[1] The polarizing plate is provided with a polarizer, a first optical film laminated on one side of the polarizer, a first adhesive layer arranged on the other side of the polarizer, and a first adhesive layer arranged on the side opposite to the polarizer side The second subsequent layer; where,

The moisture permeability of the first optical film is 100g/m ² ‧24hr or less,

The moisture permeability of the first adhesive layer is 500g/m ² ‧24hr or more,

The moisture permeability of the second adhesive layer is 100g/m ² ‧24hr or less.

[2] The polarizing plate described in [1] includes a second optical film between the first adhesive layer and the second adhesive layer, and the first adhesive layer and the second adhesive layer are in contact with the second optical film.

[3] The polarizing plate according to [1] or [2], including a third adhesive layer laminated on the surface of the first optical film on the opposite side to the polarizer side.

[4] The polarizing plate according to any one of [1] to [3], including a fourth adhesive layer laminated on the second adhesive layer on the opposite side to the polarizer side.

[5] A display device in which the polarizing plate described in [3] is laminated on the front panel via the third adhesive layer, and is laminated on the display element or touch panel via the second adhesive layer.

[6] A display device in which the polarizing plate described in [4] is laminated on the front panel via the third adhesive layer, and is laminated on the display element or the touch panel via the fourth adhesive layer.

According to the present invention, it is possible to provide a polarizing plate whose transmittance is not easy to decrease even if placed under a high temperature environment, and the degree of polarization is not easy to decrease even if placed under a high temperature and high humidity environment.

1: Polarizer

11: The first optical film

12: The second optical film

13: The third optical film

21: The first subsequent layer

22: The second subsequent layer

23: The third subsequent layer

24: 4th subsequent layer

31: front panel

32: display components

101, 102: Polarizing plate

201, 202: display device

Fig. 1 is an example of a schematic cross-sectional view showing the layer structure of a polarizing plate.

FIG. 2 is an example of a schematic cross-sectional view showing the layer structure of the display device.

〈Polarizer〉

The polarizing plate of the present invention includes a polarizer, a first optical film laminated on one side of the polarizer, a first adhesive layer arranged on the other side of the polarizer, and a first adhesive layer arranged on the side opposite to the polarizer side of the first adhesive layer. 2 then layer.

An example of the layer structure of the polarizing plate of the present invention will be specifically explained with reference to FIG. 1. The polarizing plate 101 shown in Figure 1(a) includes a polarizer 1, a first optical film 11 laminated on one side of the polarizer 1, a first adhesive layer 21 arranged on the other side of the polarizer 1, and a first adhesive layer The layer 21 is the second adhesive layer 22 on the side opposite to the polarizer 1 side. The polarizing plate 101 includes the second optical film 12 between the first adhesive layer 21 and the second adhesive layer 22, and the first adhesive layer 21 and the second adhesive layer 22 are in contact with the second optical film 12. The first adhesive layer 21 of the polarizer 101 is in contact with the polarizer 1. The polarizing plate 101 includes a third adhesive layer 23 laminated on the surface of the first optical film 11 opposite to the polarizer 1 side.

In this embodiment, the third adhesive layer 23 may be an adhesive layer for bonding to the front panel and the touch panel, and the second adhesive layer 22 may be an adhesive layer for bonding to the touch panel and display elements.

The polarizing plate 102 shown in FIG. 1(b) includes the layer shown in FIG. 1(a), and also includes a fourth adhesive layer 24 laminated on the second adhesive layer 22 on the side opposite to the polarizer 1 side. A third optical film 13 is provided between the second adhesive layer 22 and the fourth adhesive layer 24, and the second adhesive layer 22 and the fourth adhesive layer 24 are in contact with the third optical film 13.

In this embodiment, the third adhesive layer 23 may be an adhesive layer for bonding to the front panel and the touch panel, and the fourth adhesive layer 24 may be an adhesive layer for bonding to the touch panel and the display device.

The moisture permeability of the first optical film 11 is 100g/m ² ‧24hr or less, preferably 50g/m ² ‧24hr or less, and more preferably 20g/m ² ‧24hr or less. The moisture permeability of the first optical film 11 may be 0 g/m ² ‧24hr or more.

In this specification, the moisture permeability of the optical film refers to a value measured in accordance with JIS Z0208 (weight method) under the conditions of a temperature of 40°C and a relative humidity of 90%.

The moisture permeability of the first adhesive layer 21 is 500g/m ² ‧24hr or more, preferably 1000g/m ² ‧24hr or more, more preferably 3000g/m ² ‧24hr or more. The moisture permeability of the first adhesive layer 21 may be 10,000g/m ² ‧24hr or less.

The moisture permeability of the second adhesive layer 22 is 100g/m ² ‧24hr or less, preferably 50g/m ² ‧24hr or less, and more preferably 20g/m ² ‧24hr or less. The moisture permeability of the second adhesive layer 22 may be 0g/m ² ‧24hr or more.

In this specification, the moisture permeability of the adhesive layer refers to a value measured in accordance with JIS K7129 at a temperature of 40°C and a relative humidity of 90%. The test method can adopt the humidity sensor method.

The first optical film 11, the first adhesive layer 21, and the second adhesive layer 22 are respectively laminated in the above-mentioned order, and the above-mentioned moisture permeability ranges are displayed respectively, so that even when placed in a high-temperature environment, the central part of the surface penetrates The transmittance is not easy to decrease, and the polarization degree is not easy to decrease even when placed in a high temperature and high humidity environment. The first adhesive layer 21 with a high moisture permeability is likely to release the moisture in the polarizing plate under a high temperature environment, and it is unlikely that polyvinyl alcohol will be polyalkyleneized. On the other hand, the first optical film 11 and the second adhesive layer 22 with low water permeability can prevent moisture from penetrating into the polarizing plate under a high temperature and high humidity environment, thereby reducing the decrease in the degree of polarization.

The polarizing plate may have layers other than those shown in Fig. 1. Examples of the layer that the polarizing plate may be further provided include a front panel, a light-shielding pattern, and the like. The front panel can be arranged on the viewing side of the polarizer.

The light-shielding pattern may be formed on the surface of the front panel on the side of the polarizer, the surface of the polarizer on the side of the front panel, or both. The light-shielding pattern may be formed on the frame (non-display area) of the display device so that the wiring of the display device is not viewed by the user.

The shape of the main surface of the polarizer can be circular, polygonal, other patterns, and combinations thereof. The shape of the main surface of the polarizing plate may be substantially rectangular. The so-called main surface refers to the surface having the widest area corresponding to the display surface. The so-called substantially rectangular means that at least one of the four corners (corners) is cut into an obtuse or rounded shape, or a part of the end surface perpendicular to the main surface has an in-plane direction The recessed portion (notch) or a part of the main surface has an opening that is hollowed out into a shape such as a circle, an ellipse, a polygon, and a combination of these. When the polarizing plate is used for a vehicle, the shape of the main surface of the polarizing plate may be the shape of a side view mirror, the shape of a rear view mirror, or the shape of an instrument panel.

From the viewpoint of reducing the decrease in the transmittance of the central part of the plane, the size of the polarizing plate is a rectangle with a length of 6 cm or more and 35 cm or less and a short side of 5 cm or more and 30 cm or less. Preferably, it is more preferable to fit into a rectangle with a length of 10 cm or more and 30 cm or less on the long side and a length of 6 cm or more and 25 cm or less on the short side.

Hereinafter, each layer included in the polarizing plate will be described.

(1) Polarizer

The polarizer included in the polarizer may be an absorption-type polarizer that absorbs linearly polarized light having a vibration plane parallel to its absorption axis and has vibrations perpendicular to the absorption axis (parallel to the transmission axis) The linearly polarized light penetration of the surface. As the polarizer, a polarizer in which a dichroic dye is adsorbed and aligned to a uniaxially stretched polyvinyl alcohol-based resin film can be suitably used. The polarizer can be manufactured, for example, by a method including the following steps: single-stage polyvinyl alcohol-based resin film Shaft extension step; the step of dyeing the polyvinyl alcohol resin film with dichroic pigment to make it adsorb the dichroic pigment; using the crosslinking liquid such as boric acid aqueous solution to adsorb the dichroic pigment to the polyvinyl alcohol resin film The step of treatment; and the step of washing with water after treatment with the cross-linking liquid.

As the polyvinyl alcohol resin, saponified polyvinyl acetate resin can be used. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, for example, a copolymer of vinyl acetate and other monomers copolymerizable with the vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

In the present invention, "(meth)acrylic acid" refers to at least one selected from acrylic acid and methacrylic acid. The same applies to "(meth)acryloyl" and "(meth)acrylate".

The degree of saponification of the polyvinyl alcohol-based resin is generally 85 to 100 mol% or more, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified. For example, polyvinyl formaldehyde or polyvinyl acetal modified with aldehydes can be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000. The average degree of polymerization of the polyvinyl alcohol-based resin can be determined in accordance with JIS K6726.

Such polyvinyl alcohol-based resin can be used as an embryo film of a polarizer by forming a film. The method of forming a polyvinyl alcohol resin film is not particularly limited, and a conventional method can be adopted. The thickness of the polyvinyl alcohol-based raw material film is not particularly limited, but in order to make the thickness of the polarizer 15 μm or less, it is preferable to use 5 to 35 μm. More preferably, it is 20 μm or less.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be carried out before the dyeing of the dichroic dye, simultaneously with the dyeing, or after the dyeing. In the case of uniaxial extension after dyeing, the uniaxial extension can be It is carried out before or during the cross-linking treatment. Moreover, uniaxial stretching may be performed in these plural stages.

For uniaxial extension, uniaxial extension can be performed between rollers with different rotation speeds, or a hot roller can be used for uniaxial extension. In addition, the uniaxial stretching may be dry stretching in the atmosphere, or wet stretching in a state where the polyvinyl alcohol-based resin film is swelled using a solvent and water. The stretching ratio is usually 3 to 6 times.

As a method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing the film in an aqueous solution containing a dichroic dye can be adopted. As the dichroic dye, iodine or a dichroic organic dye is used. Furthermore, the polyvinyl alcohol-based resin film system is preferably immersed in water before the dyeing treatment.

For the crosslinking treatment after dyeing by a dichroic dye, a method of immersing a dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid is generally adopted. In the case of using iodine as the dichroic dye, the aqueous solution containing boric acid preferably contains potassium iodide.

From the viewpoint of reducing the amount of moisture contained in the polarizer, the thickness of the polarizer is 20 μm or less, preferably 15 μm or less, more preferably 13 μm or less, still more preferably 10 μm or less, and particularly preferably 8 μm or less. The thickness of the polarizer is usually 2 μm or more, preferably 3 μm or more. When the thickness of the polarizer is in such a range, it is easy to prevent a decrease in the transmittance of the central portion in the plane.

As the polarizer, for example, what is described in JP 2016-170368 A by aligning a dichroic dye in a cured film polymerized with a liquid crystal compound can be used. As a dichroic dye, it can be used for those having an absorber in the wavelength range of 380 to 800 nm, and organic dyes are preferably used. Examples of dichroic dyes include azo compounds. Liquid crystal compounds can be aligned A liquid crystal compound directly polymerized afterwards and may have a polymerizable group in the molecule. In addition, as described in WO2011/024891, a polarizer may be formed from a dichroic dye having liquid crystallinity.

(2) The first optical film

The first optical film may be a resin film. The first optical film may be a protective film having a function of protecting the polarizer. The protective film may be a film containing the following resin: a thermoplastic resin having light transmittance (preferably optically transparent), such as a chain polyolefin resin (polypropylene resin, etc.), a cyclic polyolefin resin ( Norbornene-based resins, etc.) of polyolefin-based resins; such as triacetyl cellulose, diacetyl-based cellulose cellulose resins; such as polyethylene terephthalate, polybutylene terephthalate Ester polyester resin; polycarbonate resin; (meth)acrylic resin such as methyl methacrylate resin; polystyrene resin; polyvinyl chloride resin; acrylonitrile/butadiene/benzene Vinyl resins; acrylonitrile/styrene resins; polyvinyl acetate resins; polyvinylidene chloride resins; polyamide resins; polyacetal resins; modified polyphenylene ether resins; polyvinylidene resins ；Polyether-based resin; Polyarylate-based resin; Polyimide-based resin; Polyimide-based resin. In the present invention, the protective film is preferably a film containing polyolefin resin or (meth)acrylic resin.

As chain polyolefin resins, in addition to polyethylene resins (polyethylene resins that are homopolymers of ethylene, copolymers based on ethylene), polypropylene resins (polypropylene resins that are propylene homopolymers, and propylene In addition to the homopolymer of the chain olefin of the main copolymer), for example, a copolymer composed of two or more kinds of chain olefins can be cited.

Cyclic polyolefin resin is a general term for resins polymerized with cyclic olefin as a polymerization unit, for example, Japanese Patent Application Publication No. 1-240517, Japanese Patent Application Publication No. 3-14882, Japanese Patent Application Publication No. 3-122137 And other resins. Specific examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, and Copolymers of olefins and chain olefins such as ethylene and propylene (represented as random copolymers), graft polymers modified with unsaturated carboxylic acids or their derivatives, and hydrogenated products. Among them, it is preferable to use norbornene-based resins using norbornene-based monomers such as norbornene and polycyclic norbornene-based monomers as cyclic olefins.

The polyester resin refers to a resin having an ester bond other than the following cellulose ester resin, and is generally composed of a polycondensate of a polycarboxylic acid or its derivative and a polyol. As the polyhydric carboxylic acid or its derivative, a divalent dicarboxylic acid or its derivative can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalate. Divalent diols can be used as the polyol, and examples thereof include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol. As a representative example of the polyester resin, for example, polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol, can be cited.

The (meth)acrylic resin is a resin mainly composed of a compound having a (meth)acryloyl group as a monomer. Specific examples of (meth)acrylic resins include, for example, poly(meth)acrylate such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymer; methyl methacrylate-( Meth) acrylate copolymer; methyl methacrylate-acrylate-(meth)acrylic acid copolymer; methyl methacrylate-styrene copolymer (MS resin, etc.); methyl methacrylate and alicyclic A copolymer of a group hydrocarbon-based compound (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). It is preferable to use a polymer mainly composed of poly(meth)acrylic acid C _1-6 alkyl such as polymethyl (meth)acrylate, and it is more preferable to use a polymer mainly composed of methyl methacrylate (50 to 100% by weight, preferably 70 to 100% by weight) of methyl methacrylate resin.

Cellulose ester resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Furthermore, these copolymers, or those in which a part of the hydroxyl group is modified with other substituents can be mentioned. Among them, particularly preferred is cellulose triacetate (triacetyl cellulose).

The polycarbonate resin refers to an engineering plastic composed of a polymer bonded to a monomer unit via a carbonate group.

The protective film can be a surface with a hard coat, anti-glare layer, light diffusion layer, anti-reflection layer, low refractive index layer, antistatic layer, and antifouling layer on its outer surface (the surface opposite to the polarizer) Treatment layer (coating layer). In addition, the thickness of the first optical film includes the thickness of the surface treatment layer. The protective film may have a phase difference.

The thickness of the first optical film is usually 10 to 100 μm, and from the viewpoint of imparting a predetermined range of moisture permeability, it is preferably 10 to 60 μm, more preferably 10 to 55 μm, and still more preferably 15 to 40 μm.

The first optical film can be bonded to a polarizer via an adhesive layer, for example. In addition, in Figs. 1 and 2, the adhesive layer adhering to the first optical film and the polarizer is omitted in the drawings. As the adhesive for forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and a water-based adhesive or an active energy ray-curable adhesive is preferable.

Examples of the water-based adhesive include an adhesive composed of a polyvinyl alcohol-based resin aqueous solution, and an aqueous two-component urethane-based latex adhesive. Among them, an aqueous adhesive composed of a polyvinyl alcohol-based resin aqueous solution is suitably used. As the polyvinyl alcohol resin, in addition to the polyvinyl alcohol homopolymer obtained by the saponification treatment of polyvinyl acetate which is a homopolymer of vinyl acetate, it can also be used for vinyl acetate and co-copolymer with the vinyl acetate. Of other monomers polymerized A polyvinyl alcohol-based copolymer obtained by saponifying the copolymer or a modified polyvinyl alcohol-based polymer obtained by partially modifying these hydroxyl groups. The water-based adhesive may include crosslinking agents such as aldehyde compounds (glyoxal, etc.), epoxy compounds, melamine compounds, methylol compounds, isocyanate compounds, amine compounds, and polyvalent metal salts.

In the case of using a water-based adhesive, it is preferable to perform a drying step to remove water contained in the water-based adhesive after bonding the polarizer and the first optical film. After the drying step, an aging step for aging, for example, at a temperature of 20 to 45°C may be provided.

The above-mentioned active energy ray curable adhesive means an adhesive agent containing a curable compound that is cured by irradiation of active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, and is preferably an ultraviolet curable adhesive agent.

The curable compound may be a cation polymerizable curable compound or a radical polymerizable curable compound. Examples of cationically polymerizable curable compounds include epoxy compounds (compounds having one or more epoxy groups in the molecule), oxetane compounds (having one or two epoxy groups in the molecule). More than one oxetanyl compound) or a combination thereof. Examples of the radically polymerizable curable compound include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), radically polymerizable double Bonds of other vinyl compounds or combinations of these. A cation polymerizable curable compound and a radical polymerizable curable compound can also be used in combination. The active energy ray curable adhesive usually further includes a cationic polymerization initiator and/or a radical polymerization initiator for initiating the curing reaction of the curable compound.

When the polarizer is bonded to the first optical film, in order to improve the adhesiveness, surface activation treatment may be performed on at least one of these bonding surfaces. Examples of surface activation treatment include: Dry treatment of corona treatment, plasma treatment, electric discharge treatment (arc discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment and ionizing radiation treatment (ultraviolet treatment, electron beam treatment, etc.); such as using water, acetone and other solvents Ultrasonic treatment, saponification treatment and wet treatment of anchoring treatment. These surface activation treatments may be performed individually or in combination of two or more.

(3) The second optical film

The second optical film can be selected from the films exemplified above as the first optical film. In this case, the materials and thicknesses of the first optical film and the second optical film may be different or the same. A retardation film can also be exemplified as the second optical film.

The retardation film is a film including at least a retardation layer. The retardation layer may be a stretched film, and the material of the stretched film may be those exemplified by the resin forming the protective film. In this case, the retardation layer may be a stretched film composed of polyolefin resin or polycarbonate resin. The retardation layer may be a layer composed of a composition containing a polymerizable liquid crystal compound. The layer composed of a composition containing a polymerizable liquid crystal compound specifically refers to a layer formed by curing the polymerizable liquid crystal compound. In this specification, a layer providing a phase difference of λ/2, a layer providing a phase difference of λ/4 (positive type A layer), a positive type C layer, etc. may be collectively referred to as a phase difference layer. In addition, the retardation film may include an alignment film described later.

The layer imparting a retardation of λ/2 preferably refers to a layer having an in-plane retardation value of 200 to 280 nm at a wavelength of 550 nm, and more preferably refers to a layer having an in-plane retardation value of 215 to 265 nm. The layer imparting a retardation of λ/4 preferably refers to a layer having an in-plane retardation value of 100 to 160 nm at a wavelength of 550 nm, and more preferably refers to a layer having an in-plane retardation value of 110 to 150 nm. The positive C layer may be a layer whose refractive index shows the relationship of nx≒ny<nz. Positive type C layer thickness direction retardation The value can be -50nm to -150nm at a wavelength of 550nm, and can be -70nm to -120nm. The retardation layer may exhibit positive wavelength dispersion or reverse wavelength dispersion.

In the case where the second optical film includes a layer imparting a λ/4 retardation, the second optical film may be set so that the angle between the slow axis of the layer imparting a λ/4 retardation and the absorption axis of the polarizer becomes approximately Layered in a 45° way. The so-called about 45° means 40° to 50°. At this time, the polarizing plate can give the function of the circular polarizing plate.

The layer formed by curing the polymerizable liquid crystal compound is formed, for example, on an alignment film provided on a substrate. The substrate has a function of supporting the alignment film, and may be a substrate formed in a long strip shape. The substrate has a function as a release support and can support a retardation layer for transfer. Furthermore, it is preferable that the surface has a peelable adhesive force. As a base material, the resin film exemplified as the material of the above-mentioned protective film is mentioned, for example.

The layer formed by curing the polymerizable liquid crystal compound is formed on the substrate via the alignment film. That is, the substrate and the alignment film are laminated in this order, and the layer formed by curing the polymerizable liquid crystal compound is laminated on the alignment film.

Furthermore, the alignment film is not limited to a vertical alignment film, and may be an alignment film that aligns the molecular axis of the polymerizable liquid crystal compound horizontally, or may be an alignment film that aligns the molecular axis of the polymerizable liquid crystal compound obliquely. The thickness of the alignment film is usually in the range of 10 nm to 10000 nm, preferably in the range of 10 nm to 1000 nm, more preferably in the range of 500 nm or less, and still more preferably in the range of 10 nm to 200 nm.

Regarding the type of polymerizable liquid crystal compound used in this embodiment, there is no particular limitation. According to its shape, it can be classified into rod-shaped (rod-shaped liquid crystal compound) and disc-shaped (disc-shaped liquid crystal compound, discotic liquid crystal compound). ). Furthermore, there are low molecular type and high molecular type. In addition, all The term "polymer" generally refers to those with a degree of polymerization of 100 or more (Polymer Physics/Phase Transition Kinetics, Masao Doi, 2 pages, Iwanami Bookstore, 1992).

In this embodiment, any polymerizable liquid crystal compound can be used. In addition, two or more rod-shaped liquid crystal compounds, two or more types of discotic liquid crystal compounds, or a mixture of rod-shaped liquid crystal compounds and discotic liquid crystal compounds may also be used.

Furthermore, as the rod-shaped liquid crystal compound, for example, those described in claim 1 of Japanese Patent Application Publication No. 11-513019 or paragraphs [0026] to [0098] of Japanese Patent Application Publication No. 2005-289980 can be suitably used. As the discotic liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP 2007-108732 A, or paragraphs [0013] to [0108] of JP 2010-244038 A can be suitably used.

Two or more types of polymerizable liquid crystal compounds can be used in combination. In this case, at least one kind has two or more polymerizable groups in the molecule. That is, the layer formed by curing the polymerizable liquid crystal compound is preferably a layer formed by fixing a liquid crystal compound having a polymerizable group by polymerization. In this case, it is no longer necessary to exhibit liquid crystallinity after the layer is formed.

The polymerizable liquid crystal compound has a polymerizable group capable of undergoing a polymerization reaction. The polymerizable group is preferably a functional group capable of undergoing an addition polymerization reaction, such as a polymerizable ethylenic unsaturated group and a cyclic polymerizable group. More specifically, examples of the polymerizable group include (meth)acrylic group, vinyl group, styryl group, and allyl group. Among them, a (meth)acryloyl group is preferred. In addition, the so-called (meth)acryloyl group is a concept including a methacryloyl group and an acrylic group.

The layer formed by curing the polymerizable liquid crystal compound can be formed by coating a composition containing the polymerizable liquid crystal compound on, for example, an alignment film, and then irradiating active energy rays such as ultraviolet rays. Components other than the above-mentioned polymerizable liquid crystal compound may be added to the composition. E.g. composition system It is preferable to include a polymerization initiator. The polymerization initiator is selected according to the type of polymerization reaction, for example, a thermal polymerization initiator and a photopolymerization initiator. For example, as the photopolymerization initiator, α-carbonyl compounds, acyloin ethers, α-hydrocarbyl substituted aromatic ketol compounds, polynuclear quinone compounds, triarylimidazole dimers and p-aminophenyl ketones The combination. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, and more preferably 0.5 to 5% by mass relative to the total solid content in the composition.

The composition may contain a polymerizable monomer from the point of the uniformity of the coating film and the strength of the film. Examples of polymerizable monomers include radically polymerizable or cationically polymerizable compounds. Among them, polyfunctional radical polymerizable monomers are preferred.

Furthermore, the polymerizable single system is preferably one that can be copolymerized with the above-mentioned polymerizable liquid crystal compound. The amount of the polymerizable monomer used is preferably 1 to 50% by mass, and more preferably 2 to 30% by mass relative to the total mass of the polymerizable liquid crystal compound.

The composition may contain a surfactant from the point of the uniformity of the coating film and the strength of the film. As surfactants, conventionally known compounds can be cited. Among them, fluorine-based compounds are particularly preferred.

The composition may contain a solvent, and the solvent may preferably be an organic solvent. Examples of the organic solvent include amide (N,N-dimethylformamide), sulfinium (dimethyl sulfinium), heterocyclic compounds (pyridine, etc.), hydrocarbons (benzene, hexane, etc.), alkyl halides (Chloroform, dichloromethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), ketones (acetone, methyl ethyl ketone, etc.), ethers (tetrahydrofuran, 1,2-dimethoxyethane, etc.) Ethane etc.). Among them, halogenated alkanes and ketones are preferred. Furthermore, two or more organic solvents can be used in combination.

The composition may include vertical alignment promoters such as a so-called vertical alignment agent on the side of the polarizer, a vertical alignment agent on the air interface side, and a horizontal alignment agent on the side of the polarizer interface, and water on the air interface side. A variety of alignment agents such as horizontal alignment accelerators. In addition to the above-mentioned components, the composition may also include adhesion modifiers, plasticizers, polymers and the like.

When the second optical film is a retardation film, the thickness of the second optical film is preferably 0.5 μm or more. Furthermore, the thickness of the second optical film is preferably 30 μm or less, more preferably 25 μm or less. When the thickness of the second optical film is greater than or equal to the aforementioned lower limit, sufficient durability can be obtained. When the thickness of the second optical film is not more than the aforementioned upper limit value, it can contribute to the thinning of the polarizing plate. The thickness of the second optical film can be such that the layer with λ/4 retardation, the layer with λ/2 retardation, or the positive C layer can obtain the desired in-plane retardation value and thickness direction retardation value. Adjustment.

(4) The third optical film

The third optical film can be selected from the films exemplified above as the first optical film or the second optical film. In this case, the materials and thicknesses of the first optical film, the second optical film, and the third optical film may be mutually different or the same. The third optical film may be a protective film or a retardation film, and is preferably a retardation film.

When both the second optical film and the third optical film are retardation films, the second optical film and the third optical film are combined with a λ/4 retardation layer and a positive C layer or a λ/4 retardation is provided The combination of the layer and the layer imparting a λ/2 phase difference is preferable.

(5) The first layer

The first adhesive layer is formed of an adhesive layer or an adhesive layer. The first adhesive layer is preferably an adhesive layer. The first adhesive layer may have a function of laminating the above-mentioned second optical film and polarizer. The first adhesive layer can be arranged on the display element side (that is, the side opposite to the viewing side) based on the polarizer. The first adhesive layer is in contact with the polarizer.

Since it is easy to control the moisture permeability within the above range, the adhesive layer forming the first adhesive layer is preferably an aqueous adhesive layer. Examples of water-based adhesives include polyvinyl alcohol-based resin water Adhesives composed of solutions, water-based two-component urethane-based latex adhesives, etc. Among them, an aqueous adhesive composed of a polyvinyl alcohol-based resin aqueous solution is suitably used. As the polyvinyl alcohol resin, in addition to the polyvinyl alcohol homopolymer obtained by the saponification treatment of polyvinyl acetate, which is a homopolymer of vinyl acetate, vinyl acetate and those that can be copolymerized with the vinyl acetate can also be used. Polyvinyl alcohol copolymers obtained by saponification of copolymers of other monomers or modified polyvinyl alcohol polymers with partially modified hydroxyl groups. The water-based adhesive may include crosslinking agents such as aldehyde compounds (glyoxal, etc.), epoxy compounds, melamine compounds, methylol compounds, isocyanate compounds, amine compounds, and polyvalent metal salts. The thickness of the water-based adhesive layer may be 1 μm or less.

The first adhesive layer may be formed of an adhesive layer. The adhesive layer may be composed of an adhesive composition mainly composed of (meth)acrylic, urethane, ester, silicone, or polyvinyl ether resin. Among them, since it is easy to control the moisture permeability, it is suitable as an adhesive composition using a (meth)acrylic resin as a matrix polymer. The adhesive composition can be an active energy ray hardening type or a heat hardening type. The thickness of the adhesive layer is usually 3 to 30 μm, preferably 3 to 25 μm.

As the (meth)acrylic resin (matrix polymer) used in the adhesive composition, for example, butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, One or two or more of (meth)acrylates of 2-ethylhexyl (meth)acrylate are polymers or copolymers of monomers. The matrix polymer is preferably copolymerized with a polar monomer. Examples of polar monomers include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, and N,N-dimethylamino. Monomers such as ethyl (meth)acrylate and glycidyl (meth)acrylate, which have a carboxyl group, a hydroxyl group, an amide group, an amino group, and an epoxy group.

The adhesive composition may contain only the aforementioned matrix polymer, and usually contains a crosslinking agent. Examples of crosslinking agents include metal ions having a valence of 2 or higher and forming carboxyl groups with carboxyl groups. Acid metal salt; those belonging to polyamine compounds and forming amide bonds with carboxyl groups; those belonging to polyepoxy compounds or polyols and forming ester bonds with carboxyl groups; those belonging to polyisocyanate compounds and forming amide bonds with carboxyl groups Key person. Among them, polyisocyanate compounds are preferred.

(6) The second layer

The second adhesive layer is formed of an adhesive layer or an adhesive layer. The second adhesive layer is preferably an adhesive layer. The second adhesive layer may have the function of laminating the second optical film and the third optical film, or the function of laminating the second optical film and the touch panel or display element.

Since it is easy to control the moisture permeability within the above range, the adhesive layer forming the second adhesive layer is preferably an active energy ray-curable adhesive layer. The so-called active energy ray curable adhesive is an adhesive containing a curable compound that is cured by irradiation of active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, and is preferably an ultraviolet curable adhesive.

The curable compound may be a cation polymerizable curable compound or a radical polymerizable curable compound. Examples of cationically polymerizable curable compounds include epoxy compounds (compounds having one or more epoxy groups in the molecule), oxetane compounds (having one or two epoxy groups in the molecule). More than one oxetane ring compound) or a combination thereof. Examples of the radically polymerizable curable compound include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), radically polymerizable double Bonds of other vinyl compounds or combinations of these. A cation polymerizable curable compound and a radical polymerizable curable compound can also be used in combination. The active energy ray curable adhesive usually further includes a cationic polymerization initiator and/or a radical polymerization initiator for initiating the curing reaction of the curable compound. The thickness of the active energy ray-curable adhesive layer may be 0.5 μm or more and 2 μm or less.

The second adhesive layer may be formed of an adhesive layer. From the viewpoint of controlling the moisture permeability to a predetermined range and imparting adhesive force, the adhesive layer is preferably a rubber-based adhesive or a polyolefin-based adhesive. The adhesive composition can be an active energy ray hardening type or a heat hardening type. The thickness of the adhesive layer is usually 3 to 50 μm, preferably 3 to 30 μm.

The rubber-based adhesive may be any one containing a rubber-based polymer. The rubber-based polymer is a polymer showing rubber elasticity in a temperature range around room temperature. Specifically, styrene-based thermoplastic elastomers, isobutylene-based polymers, and the like can be cited. From the viewpoint of weather resistance, it is preferable to use polyisobutylene (PIB) which is a homopolymer of isobutylene. Since polyisobutylene does not contain double bonds in the main chain, it has good light resistance. As the polyisobutylene, commercially available products such as OPPANOL manufactured by BASF Corporation can be used.

The weight average molecular weight (Mw) of polyisobutylene is preferably 100,000 or more, more preferably 300,000 or more, still more preferably 600,000 or more, particularly preferably 700,000 or more. Furthermore, the upper limit of the weight average molecular weight is not particularly limited, and is preferably 5 million or less, more preferably 3 million or less, and still more preferably 2 million or less. By setting the weight average molecular weight of polyisobutylene to 100,000 or more, it is possible to form a rubber-based adhesive composition with more excellent durability during high-temperature storage.

The content of polyisobutylene in the total solid content of the rubber-based adhesive composition is preferably 50% by weight or more, more preferably 60% by weight or more, still more preferably 70% by weight or more, and still more preferably 80% by weight or more , More preferably 85% by weight or more, particularly preferably 90% by weight or more. The upper limit of the content of polyisobutylene is not particularly limited, but is preferably 99% by weight or less, and more preferably 98% by weight or less. When polyisobutylene in the aforementioned range is contained, it is excellent in low moisture permeability and is therefore preferred.

Furthermore, the rubber-based adhesive used in the present invention may include polymers, elastomers, etc. other than polyisobutylene. Specifically, examples include: copolymers of isobutylene and n-butene, copolymers of isobutylene and isoprene (such as ordinary butyl rubber, chlorinated butyl rubber, bromobutyl rubber, and partially crosslinked butyl rubber, etc.) Butyl rubbers), these sulfides, modified products (for example, those modified with functional groups such as hydroxyl, carboxyl, amino, epoxy) and other isobutylene-based polymers; styrene-ethylene-butene- Styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene- Propylene-styrene block copolymer (SEPS, SIS hydrogenated product), styrene-ethylene-propylene block copolymer (SEP, styrene-isoprene block copolymer hydrogenated product), styrene-isobutylene- Styrenic thermoplastic elastomers such as styrene block copolymers (SIBS) and styrene-butadiene rubber (SBR); butyl rubber (IIR), butadiene rubber (BR) , Acrylonitrile-butadiene rubber (NBR), EPR (diethylene-propylene rubber), EPT (ternary ethylene-propylene rubber), acrylic rubber, urethane rubber, polyurethane-based thermoplastic elastomer; polyester-based thermoplastic elastomer Body; blended thermoplastic elastomers such as blends of polymers of polypropylene and EPT (terene-ethylene-propylene rubber). These can be added in a range that does not impair the effect of the present invention, but it is preferably about 10 parts by weight or less relative to 100 parts by weight of the aforementioned polyisobutylene, and it is preferably not included from the viewpoint of durability.

In addition, the rubber-based adhesive particularly preferably contains polyisobutylene and a hydrogen-extraction type photopolymerization initiator. The so-called hydrogen extraction type photopolymerization initiator refers to the one that can extract hydrogen from the polyisobutylene by irradiating active energy rays without the initiator itself being cracked to form a reaction point in the polyisobutylene. By forming reaction points, the crosslinking reaction of polyisobutylene can be initiated.

As the photopolymerization initiator, in addition to the hydrogen extraction type photopolymerization initiator used in the present invention, a cleavage type photopolymerization initiator that generates radicals due to the cleavage of the photopolymerization initiator itself is known. Beginner. However, when a cleavage-type photopolymerization initiator is used for the polyisobutylene used in the present invention, the main chain of the polyisobutylene is cut and cannot be crosslinked due to the photopolymerization initiator that generates radicals. In the present invention, the polyisobutylene can be crosslinked by using a hydrogen-extraction type photopolymerization initiator as described above.

Examples of the hydrogen-pumping type photopolymerization initiator include benzophenone-based compounds, thioxanthone-based compounds, aminobenzophenone-based compounds, aromatic ketone compounds, and quinone-based aromatic compounds. These can be used individually by 1 type or in mixture of 2 or more types. From the point of reactivity, a benzophenone-based compound is preferred, and benzophenone is more preferred.

The content of the hydrogen extraction type photopolymerization initiator is preferably 0.001 to 10 parts by weight, more preferably 0.005 to 10 parts by weight, and still more preferably 0.01 to 10 parts by weight relative to 100 parts by weight of the aforementioned polyisobutylene. By containing the hydrogen extraction type photopolymerization initiator in the aforementioned range, the crosslinking reaction can be advanced to the target density, which is preferable.

The rubber-based adhesive may further contain a polyfunctional radical polymerizable compound. The polyfunctional radical polymerizable compound has a function as a crosslinking agent for polyisobutylene. The polyfunctional radical polymerizable compound is a compound having at least two (meth)acrylic acid groups or vinyl groups and other radically polymerizable functional groups having unsaturated double bonds.

The content of the polyfunctional radical polymerizable compound is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and still more preferably 10 parts by weight or less with respect to 100 parts by weight of polyisobutylene. Furthermore, the lower limit of the content of the polyfunctional radical polymerizable compound is not particularly limited. For example, relative to 100 parts by weight of polyisobutylene, it is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, and still more preferably 1 Parts by weight or more. By setting the content of the polyfunctional radical polymerizable compound within the aforementioned range, the durability of the resulting rubber-based adhesive layer can be improved.

The rubber-based adhesive used in the present invention may include at least one type of tackifier selected from the group consisting of a tackifier containing a terpene skeleton, a tackifier containing a rosin skeleton, and these hydrides. By including the tackifier in the rubber-based adhesive, it is possible to form a rubber-based adhesive layer that has high adhesion to various adherends and high durability even in a high-temperature environment.

The rubber-based adhesive may contain an organic solvent. As an organic solvent, toluene, xylene, n-heptane, dimethyl ether, etc. are mentioned, for example, These can be used individually by 1 type or in mixture of 2 or more types. Among these, toluene is preferred.

In the range that does not impair the effect of the present invention, the rubber-based adhesive may be added with additives other than the foregoing. Specific examples of additives include softeners, crosslinking agents (for example, polyisocyanates, epoxy compounds, alkyl etherified melamine compounds, etc.), fillers, anti-aging agents, ultraviolet absorbers, and the like.

The rubber-based adhesive layer may be formed of the aforementioned adhesive. The rubber-based adhesive layer can be formed by applying an adhesive to various supports, etc., heating and drying, irradiating active energy rays, and the like.

The polyolefin-based adhesive may be any one containing polyolefin-based resin. Specific examples of polyolefin resins include low-density polyethylene, ultra-low-density polyethylene, low-crystalline polyethylene, amorphous propylene-(1-butene) copolymer, ionomer resin, ethylene-vinyl acetate Copolymers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylate-maleic anhydride copolymers, ethylene-glycidyl methacrylate copolymers and other ethylene copolymers, polyolefin modified polymers Wait. The polyolefin-based adhesive more preferably includes an amorphous polypropylene resin, and more preferably includes an amorphous propylene-(1-butene) copolymer. With such an adhesive, an adhesive layer with excellent step compliance can be obtained. Furthermore, in this specification, the term "amorphous" refers to the property that does not have a clear melting point like crystalline.

The content ratio of the amorphous propylene-(1-butene) copolymer contained in the adhesive can be appropriately adjusted so that the elasticity value of the adhesive layer becomes 0.7 N/mm or less. The content ratio of the amorphous propylene-(1-butene) copolymer contained in the adhesive is preferably 10% by weight to 100% by weight, more preferably 10% by weight to 95% by weight, in terms of weight ratio.

Preferably, the amorphous propylene-(1-butene) copolymer can be obtained by polymerizing propylene and 1-butene using a metallocene catalyst. In more detail, the amorphous propylene-(1-butene) copolymer can be obtained, for example, by a polymerization step of polymerizing propylene and 1-butene using a metallocene catalyst, and after the polymerization step , Perform post-processing steps such as the step of removing the remaining catalyst and the step of removing foreign matter. The amorphous propylene-(1-butene) copolymer can be obtained in a shape such as a powder, a granule, etc. through such a process. Examples of the metallocene catalyst include a metallocene homogeneous mixed catalyst containing a metallocene compound and aluminoxane, and a metallocene-supported catalyst in which the metallocene compound is supported on a fine particle carrier.

As described above, the amorphous propylene-(1-butene) copolymer system polymerized using a metallocene catalyst shows a narrow molecular weight distribution. The molecular weight distribution (Mw/Mn) of the above-mentioned amorphous propylene-(1-butene) copolymer is preferably 3 or less, more preferably 2 or less, still more preferably 1.1 to 2, particularly preferably 1.2 to 1.9. The amorphous propylene-(1-butene) copolymer with a narrow molecular weight distribution has less low molecular weight components. Therefore, when such an amorphous propylene-(1-butene) copolymer is used, it can prevent the low molecular weight The exudation of the ingredients causes contamination of the adhesive layer of the adherend.

The content ratio of the propylene-derived structural unit of the amorphous propylene-(1-butene) copolymer is preferably 80 mol% to 99 mol%, more preferably 85 mol% to 99 mol%, and more Preferably, it is 90 mol% to 99 mol%.

The content ratio of the structural unit derived from 1-butene in the amorphous propylene-(1-butene) copolymer is preferably 1 mol% to 20 mol%, more preferably 1 mol% to 15 mol% , And more preferably 1 mol% to 10 mol%. If it is in such a range, an adhesive layer with an excellent balance of toughness and flexibility can be obtained.

The amorphous propylene-(1-butene) copolymer may be a block copolymer or a random copolymer.

The weight average molecular weight (Mw) of the amorphous propylene-(1-butene) copolymer is preferably 200,000 or more, more preferably 200,000 to 500,000, and still more preferably 200,000 to 300,000. When the weight average molecular weight (Mw) of the amorphous propylene-(1-butene) copolymer is in such a range, compared with general styrene-based thermoplastic resins and acrylic-based thermoplastic resins (Mw of 100,000 or less), low molecular weight components To be less, an adhesive layer that can prevent contamination of the adherend can be obtained.

The melt mass flow rate of the amorphous propylene-(1-butene) copolymer at 230°C and 2.16kgf is preferably 1g/10min to 50g/10min, more preferably 5g/10min to 30g/10min , And more preferably 5g/10 minutes to 20g/10 minutes. When the melt mass flow rate of the amorphous propylene-(1-butene) copolymer is in such a range, by co-extrusion molding, an adhesive layer with no processing defects and uniform thickness can be formed. The melt mass flow rate can be measured according to the method of JIS K7210.

The amorphous propylene-(1-butene) copolymer may further include structural units derived from other monomers. Examples of other monomers include ethylene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, 3-methyl-1-pentene, etc. -Olefin etc.

The polyolefin adhesive layer preferably further contains a crystalline polypropylene resin. By containing the crystalline polypropylene resin, the elastic modulus E'at 70°C of the adhesive layer can be adjusted to a desired value. The content ratio of the crystalline polypropylene resin can be set according to the desired elastic modulus E' Set to any suitable ratio. The content ratio of the crystalline polypropylene resin is preferably 0% to 90% by weight, and more preferably 5 to the total weight of the amorphous propylene-(1-butene) copolymer and the crystalline polypropylene resin. Weight% to 90% by weight.

The crystalline polypropylene resin may be a homopolypropylene or a copolymer obtained from propylene and a monomer copolymerizable with propylene. Examples of monomers copolymerizable with propylene include ethylene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, 3-methyl-1 -Alpha-olefins such as pentene, etc. When the crystalline polypropylene resin is a copolymer obtained from propylene and a monomer copolymerizable with propylene, it may be a random copolymer or a block copolymer.

The crystalline polypropylene resin is obtained by polymerization using a metallocene catalyst. When the crystalline polypropylene resin obtained in this way is used, it can prevent the contamination of the adherend due to the exudation of low molecular weight components.

Within a range that does not impair the effects of the present invention, the polyolefin-based adhesive layer may further contain other components. Examples of the other components include antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, and antistatic agents. The types and usage amounts of other components can be appropriately selected according to the purpose.

The polyolefin-based adhesive layer can be formed of the aforementioned adhesive, and its production method is not particularly limited. The adhesive layer can be formed by extrusion molding the adhesive on various supports, etc., and heating and drying, irradiation with active energy rays, etc. .

The molding temperature of extrusion molding is preferably 160°C to 220°C, more preferably 170°C to 200°C. In such a range, the forming stability is good.

(7) The third adhesive layer, the fourth adhesive layer

The third adhesive layer and the fourth adhesive layer are formed of an adhesive layer or an adhesive layer. The third adhesive layer may have a function of laminating the first optical film and the touch panel or the front panel. The fourth adhesive layer may have a function of laminating the third optical film and the touch panel or display element.

The third adhesive layer and the fourth adhesive layer may be formed of the adhesive layer or the adhesive layer exemplified as the first adhesive layer or the second adhesive layer, and preferably are the adhesive layer or the adhesive layer exemplified as the first adhesive layer form. The third adhesive layer and the fourth adhesive layer are preferably adhesive layers. The materials and thicknesses of the third adhesive layer and the fourth adhesive layer may be the same or different from each other.

From the viewpoint of further reducing the decrease in the transmittance of the central portion in the plane, the thickness of the third adhesive layer and the fourth adhesive layer are independently preferably 10 μm or more, more preferably 15 μm or more, more preferably, 30 μm or more . The thickness of the third adhesive layer and the fourth adhesive layer is preferably 200 μm or less, more preferably 150 μm or less.

<Display device>

The display device of the present invention includes the above-mentioned polarizing plate. The type of display device is not particularly limited, and may be a liquid crystal display device, an organic EL display device, an inorganic EL display device, and a plasma display device.

An example of the layer structure of the display device of the present invention will be specifically explained with reference to FIG. 2. In the display device 201 shown in Fig. 2(a), the polarizing plate 101 shown in Fig. 1(a) is laminated on the front panel 31 with the third adhesive layer 23 therebetween, and on the display element 32 with the second adhesive layer 22 therebetween. By. In the display device 202 shown in Fig. 2(b), the polarizing plate 102 shown in Fig. 1(b) is laminated on the front panel 31 via the third adhesive layer 23, and laminated on the display element 32 via the fourth adhesive layer 24 By. Although not shown, one of the front panel and the display element can be replaced with a touch panel.

(1) Front panel

The front panel is arranged on the viewing side of the polarizer. The front panel can be laminated on the polarizing plate via the third adhesive layer.

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

The front panel that includes a hard coat layer on at least one side of the resin film is not as rigid as existing glass, but has flexibility. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 to 100 μm.

The resin film may be cycloolefin derivatives, cellulose (diacetyl cellulose, triacetyl cellulose, etc.) having units of cycloolefin-containing monomers such as norbornene or polycyclic norbornene monomers. Cellulose, acetyl cellulose butyrate, isobutyl cellulose, propyl cellulose, butyl cellulose, acetyl propyl cellulose) ethylene-vinyl acetate copolymer, polycyclic olefin, polyester , Polystyrene, polyamide, polyetherimide, polyacrylic acid, polyimide, polyimide, polyether, polyvinyl, polypropylene, polymethylpentene, poly Vinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ether, polyether agglomerate, polymethyl methacrylate, polyethylene terephthalate, polyethylene Films formed by polymers such as butyl phthalate, polyethylene naphthalate, polycarbonate, polyurethane, and epoxy resin. As the resin film, an unstretched, one-axis or two-axis stretched film can be used. These polymers may be used individually, or two or more of them may be mixed and used. The resin film is preferably a polyimide film or a polyimide film having excellent transparency and heat resistance, a polyester film stretched in one or two axes, and one that has excellent transparency and heat resistance and can be used for film Large-scale cycloolefin derivative film, polymethyl methacrylate film and transparent and non-optical anisotropy Triacetyl cellulose and isobutyl cellulose film. The thickness of the resin film is 5 to 200 μm, preferably 20 to 100 μm.

The hard coat layer can be formed by hardening a hard coat composition containing a reactive material that forms a crosslinked structure by irradiating light or thermal energy. The hard coat layer can be formed by curing a hard coat composition containing both a photocurable (meth)acrylate monomer or oligomer and a photocurable epoxy monomer or oligomer. The photocurable (meth)acrylate monomer may include one or more selected from the group consisting of epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate . The epoxy (meth)acrylate can be obtained by reacting an epoxy compound with a carboxylic acid having a (meth)acryloyl group.

The hard coating composition may further include one or more selected from the group consisting of photoinitiators and additives. Additives may include one or more selected from the group consisting of inorganic nanoparticles, leveling agents and stabilizers. In addition, they may further include antioxidants, UV absorbers, surfactants, lubricants, antifouling agents, etc. Various ingredients commonly used in this technical field.

(2) Shading graphics

The light-shielding pattern may be provided as a front panel or at least a part of a frame or housing of a display device to which the front panel is applied. The light-shielding pattern may be formed on the surface of the front panel on the side of the polarizer, the surface of the polarizer on the side of the front panel, or both. The shading pattern can be set to hide the wiring of the display device so as not to be seen by the user. The color and/or material of the light-shielding pattern is not particularly limited, and may be formed of resin materials with various colors such as black, white, and gold.

The thickness of the light-shielding pattern may be 2 μm to 50 μm, preferably 4 μm to 30 μm, more preferably 6 μm to 15 μm. In addition, in order to suppress the visibility of bubbles and boundaries mixed in due to the step difference between the light-shielding pattern and the display portion, a light-shielding pattern shape may be given.

(3) Display components

Examples of display elements include liquid crystal display elements, organic EL display elements, inorganic EL display elements, plasma display elements, and the like. Specifically, for example, a liquid crystal display element includes a first substrate and a second substrate. The first substrate is a thin film transistor substrate having a plurality of thin film transistors (TFT) formed in a matrix. The second substrate is a counter substrate that is arranged opposite to the first substrate and has a color filter. The organic EL display element has a thin film structure in which an organic light emitting material layer is sandwiched between a pair of opposed electrodes. While injecting electrons from one electrode to the organic light-emitting material layer, holes are injected from the other electrode, so that the electrons and holes are combined in the organic light-emitting material layer to emit light. Compared with liquid crystal display elements that require a backlight, it has the advantages of better visibility, thinner thickness, and low-voltage direct current driving.

(4) Touch panel

The touch panel includes a substrate, a lower electrode provided on the substrate, an upper electrode facing the lower electrode, and an insulating layer sandwiched between the lower electrode and the upper electrode. As long as the substrate is a flexible resin film having light permeability, various resin films can be used. For example, the film exemplified above as the material of the first optical film can be used as the substrate.

The lower electrode system has, for example, a plurality of small electrodes that are square in plan view. A plurality of small electrodes are arranged in a matrix. The plurality of small electrodes are connected to each other by small electrodes adjacent in the diagonal direction of the small electrodes to form a plurality of electrode rows. A plurality of electrode rows are connected to each other at the ends, and the capacitance between adjacent electrode rows can be detected.

The upper electrode has, for example, a plurality of small electrodes having a square shape in plan view. The plurality of small electrodes are not arranged at the position where the lower electrode is arranged in a plan view, and are arranged complementary in a matrix. That is, the upper electrode and the lower electrode are arranged without a gap in a plan view. A plurality of small electrodes Small electrodes adjacent in the other diagonal direction of the pole are connected to each other to form a plurality of electrode rows. A plurality of electrode rows are connected to each other at the ends, and the capacitance between adjacent electrode rows can be detected.

The insulating layer insulates the upper electrode from the lower electrode. The material for forming the insulating layer can be a material generally known as a material for the insulating layer of a touch panel.

Furthermore, in this embodiment, although it is described that the touch panel is a so-called projected capacitive touch sensor, other types of touch panels such as a film resistance type can also be used within the scope of the effect of the invention.

<Manufacturing method of polarizing plate>

Taking the polarizing plate 101 shown in Fig. 1(a) as an example, a method of manufacturing the polarizing plate will be described. The polarizing plate 101 is obtained by the following steps: a step of bonding the polarizer 1 and the first optical film 11 through an adhesive, a step of bonding the polarizer 1 and the second optical film 12 through the first adhesive layer 21, The step of laminating the second adhesive layer 22 on the second optical film and the step of laminating the third adhesive layer 23 on the first optical film 11.

The polarizing plate 101 can be manufactured by preparing a long member, laminating each member in a roll-to-roll manner, and cutting it into a predetermined shape, or cutting each member into a predetermined shape and then bonding it.

(Example)

(1) Measuring method of film thickness

Measured using a digital micrometer MH-15M manufactured by Nikon Co., Ltd.

(2) Phase difference measurement method

The phase difference measurement device KOBRA-WPR (manufactured by Oji Measuring Instruments Co., Ltd.) was used for measurement.

(3) Measuring method of moisture permeability of optical film

The moisture permeability is measured in accordance with JIS Z0208 (weight method) at a temperature of 40°C and a relative humidity of 90%.

(4) Measuring method of moisture permeability of adhesive layer

The moisture permeability of the next layer was measured using a water vapor permeability meter (L80 series manufactured by Lyssy) in accordance with JIS K7129 at a temperature of 40° C. and a relative humidity of 90%. The test method adopts the humidity sensor method.

[Polarizer]

A polyvinyl alcohol film with a thickness of 20μm (average degree of polymerization of about 2400, degree of saponification of 99.9 mol% or more) is stretched uniaxially to about 5 times in the longitudinal direction by dry stretching, and is immersed in a pure state of 60°C while maintaining the tension. After 1 minute in water, it was immersed in a 28°C aqueous solution with a weight ratio of iodine/potassium iodide/water of 0.05/5/100 for 60 seconds. Then, it was immersed in a 72°C aqueous solution with a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 for 300 seconds. Next, after washing with pure water at 26° C. for 20 seconds, it was dried at 65° C. to obtain a polarizer with a thickness of 8 μm in which iodine was adsorbed and aligned on the polyvinyl alcohol film.

[First Optical Film]

First optical film A: Prepare a cyclic olefin resin film having a hard coat layer on one surface and being stretched. The thickness of the first optical film A is 30 μm. The moisture permeability of the first optical film A is 20g/m ² ‧24hr.

The first optical film B: Prepare a triacetyl cellulose film. The thickness of the first optical film B is 40 μm. The moisture permeability of the first optical film B is 600g/m ² ‧24hr.

[Second Optical Film]

The second optical film A: Manufactured in the following manner. 5 parts (weight average molecular weight: 30,000) of the photo-alignment material with the following structure and 95 parts of cyclopentanone (solvent) were mixed, and the resulting mixture was stirred at 80° C. for 1 hour to obtain an alignment film forming composition.

To 100 parts of the mixture after mixing the polymerizable liquid crystal compound 1 and the polymerizable liquid crystal compound 2 at a mass ratio of 90:10 as shown below, add 1.0 part of a leveling agent (F-556; manufactured by DIC) and start the polymerization 6 parts of 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one ("Irgacure 369(Irg369)", manufactured by BASF Japan Co., Ltd.) .

Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration might become 13%, and it stirred at 80 degreeC for 1 hour, and obtained the composition for liquid crystal cured film formation.

The polymerizable liquid crystal compound 1 was manufactured according to the method described in JP 2010-31223 A. In addition, the polymerizable liquid crystal compound 2 was manufactured according to the method described in JP 2009-173893 A. The structure of each molecule is shown below.

(Polymerizable liquid crystal compound 1)

(Polymerizable liquid crystal compound 2)

Corona treatment was performed on a 50 μm-thick cycloolefin-based film (trade name "ZF-14-50" manufactured by ZEON Co., Ltd., Japan) as a base material. , Use a bar coater to coat the alignment film forming composition on the corona-treated surface. The coating film was dried at 80°C for 1 minute. A polarized UV irradiation device [trade name "SPOT CURE SP-9" of Ushio Electric Co., Ltd.] was used on the dried coating film, and polarized UV was irradiated at an axis angle of 45° to obtain an alignment film. The irradiation of the polarized UV was performed so that the cumulative light quantity at a wavelength of 313 nm became 100 mJ/cm ² .

Then, the composition for forming an aligned liquid crystal cured film was coated on the alignment film using a bar coater. The coating film was dried at 120°C for 1 minute. A high-pressure mercury lamp (trade name of Ushio Electric Co., Ltd.: "UNICURE VB-15201BY-A"] was used to irradiate ultraviolet rays on the dried coating film. The ultraviolet irradiation step is performed in a nitrogen atmosphere so that the accumulated light amount at a wavelength of 365 nm becomes 500 mJ/cm ² . In this manner, a laminate including a base material, an alignment film, and a layer formed by curing a polymerizable liquid crystal compound is obtained.

(Measurement of phase difference value)

The retardation value Re(λ) of the retardation layer at each wavelength has Re(450)=121nm, Re(550)=142nm, and Re(650)=146nm. As a result, Re(450)/Re(550)=0.85 and Re(650)/Re(550)=1.03 are calculated. The retardation layer is a layer that provides a retardation of λ/4.

The second optical film B: Prepare a film in which a layer formed by curing a polymerizable liquid crystal compound is formed on a stretched cyclic olefin-based resin film. The stretched cyclic olefin-based resin film is a layer that provides a phase difference of λ/4, and the layer formed by curing the polymerizable liquid crystal compound is a positive C layer. The thickness of the second optical film B is 21 μm. The moisture permeability of the second optical film B is 20g/m ² ‧24hr.

The second optical film C: prepare a triacetyl cellulose film. The thickness of the second optical film C is 20 μm. The moisture permeability of the second optical film C is 1600 g/m ² ‧24hr.

[1st next layer]

First Adhesive Layer A: In a reaction vessel equipped with a stirrer, a thermometer, a reflux cooler, a dripping device, and a nitrogen introduction tube, 97.0 parts by mass of n-butyl acrylate, 1.0 part by mass of acrylic acid, and 0.5 parts by mass of 2-hydroxyethyl acrylate are added Parts, 200 parts by mass of ethyl acetate and 0.08 parts by mass of 2,2'-azobisisobutyronitrile, and the air in the reaction vessel was replaced with nitrogen. In a nitrogen environment, The reaction solution was heated to 60°C while stirring, and after reacting for 6 hours, it was cooled to room temperature. The weight average molecular weight of the obtained acrylate polymer was 1.8 million.

100 parts by mass of the (meth)acrylate polymer obtained in the above steps (value converted from solid content; the same below), as an isocyanate-based crosslinking agent, trimethylolpropane modified toluene diisocyanate (Tosoh Co., Ltd. (Trade name "Coronate (registered trademark) L") 0.30 parts by mass and 0.30 parts by mass of 3-glycidylpropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM403") as a silane coupling agent And fully agitate and dilute with ethyl acetate to obtain an adhesive composition.

The adhesive composition is coated on the release-treated base film so that the thickness after drying becomes 25 μm. The adhesive composition was dried at 100°C for 1 minute to obtain the first adhesive layer A. The moisture permeability of the first adhesive layer A is 3600g/m ² ‧24hr.

First adhesive layer B: After mixing and degassing the following components, the adhesive forming the first adhesive layer B is adjusted. The adhesive is an ultraviolet curable adhesive.

3,4-Epoxycyclohexanecarboxylic acid 3',4'-epoxycyclohexyl methyl ester (trade name: CEL2021P, manufactured by DAICEL): 70 parts by mass

Neopentyl glycol diglycidyl ether (trade name: EX-211, manufactured by NAGASE CHEMTEX Co., Ltd.): 20 parts by mass

2-Ethylhexyl glycidyl ether (trade name: EX-121, manufactured by NAGASE CHEMTEX Co., Ltd.): 10 parts by mass

Cationic polymerization initiator (trade name: CPI-100, manufactured by San Apro Co., Ltd.): 2.25 parts by mass of solid content (prepared as a 50% propylene carbonate solution)

1,4-Diepoxynaphthalene: 2 parts by mass

First adhesive layer C: The following components are mixed with 100 parts by mass of water to adjust the adhesive forming the first adhesive layer C. This adhesive is a water-based adhesive.

Carboxyl-modified polyvinyl alcohol [Kuraray Co., Ltd. "KL-318"]: 3 parts by mass

Polyamide epoxy-based additives that are water-soluble epoxy resins [trade name "SUMIREZ RESIN (registered trademark) 650(30)" manufactured by Taoka Chemical Industry Co., Ltd., an aqueous solution with a solid content of 30% by weight]: 1.5 mass Share

[Second second floor]

The second adhesive layer A: 100 parts by weight of polyisobutylene (trade name: OPPANOL B80, Mw: about 750,000, manufactured by BASF Corporation), tricyclodecane dimethanol diacrylic acid as a polyfunctional radical polymerizable compound Ester (trade name: NK ESTER A-DCP, difunctional acrylate, molecular weight: 304, manufactured by Shinnakamura Chemical Industry Co., Ltd.) 10 parts by weight, benzophenone (and A toluene solution (adhesive solution) of 0.5 parts by Kopure Pure Chemicals Co., Ltd. and 10 parts by weight of fully hydrogenated terpene phenol was adjusted so that the solid content was 15% by weight to prepare a rubber-based adhesive (solution).

A rubber-based adhesive (solution) is applied to the release-treated surface of a 38μm-thick polyester film (trade name DIAFOIL MRF, manufactured by Mitsubishi Plastics Co., Ltd.) that has been treated with silicone release on one side to form a coating layer . Then, the coating layer was dried at 80°C for 3 minutes to form an adhesive layer, and an adhesive sheet having a thickness of the adhesive layer of 20 μm was produced. Moreover, on the adhesive surface of the adhesive sheet, a polyester film (trade name DIAFOIL MRF, manufactured by Mitsubishi Resin (Stock)) with a thickness of 38 μm, which has been peeled off by silicone on one side, so that the peeled surface and the aforementioned adhesive layer The way of connection fits. The polyester film covering both surfaces of the adhesive layer has a function as a release film (separator). One of the separators was peeled off, and ultraviolet rays were irradiated at room temperature from the side of the peeled separator to obtain an adhesive sheet composed of the second adhesive layer A/separator. The UVA area is irradiated with ultraviolet rays so that the accumulated light amount becomes 1000 mJ/cm ² . The moisture permeability of the second adhesive layer A is 20g/m ² ‧24hr.

Second adhesive layer B: In the same manner as the first adhesive layer A, an adhesive composition was obtained. The adhesive composition was applied to the release-treated substrate so that the thickness after drying became 25 μm. The adhesive composition was dried at 100°C for 1 minute to obtain the first adhesive layer A. The moisture permeability of the second adhesive layer B is 3600g/m ² ‧24hr.

[3rd next layer]

Third adhesive layer A: The same adhesive as the first adhesive layer A was used. The adhesive composition was applied to the release-treated substrate so that the thickness after drying became 100 μm. The adhesive composition was dried at 100°C for 1 minute to obtain a third adhesive layer A. The moisture permeability of the third adhesive layer A is 900g/m ² ‧24hr.

[Example 1]

The polarizer 1 and the first optical film A are bonded to each other via a water-based adhesive. The first adhesive layer A is laminated on the layer formed by curing the polymerizable liquid crystal compound of the second optical film A. After peeling the base film laminated on the first adhesive layer A, the second optical film A and the polarizer are bonded via the exposed first adhesive layer A. After peeling the base film on which the second optical film A was laminated, the second adhesive layer A was laminated on the exposed alignment film. Furthermore, a third adhesive layer A is laminated on the first optical film A. In addition, when bonding each layer, corona treatment is given to the bonding surface. In this way, a polarizing plate in which the third adhesive layer A/the first optical film A/polarizer/the first adhesive layer A/the second optical film A/the second adhesive layer A was laminated in this order was obtained.

[Comparative Example 1]

The polarizer and the first optical film A were bonded to each other via an aqueous adhesive. On the stretched cyclic olefin resin film of the second optical film B, an adhesive for forming the first adhesive layer B is applied. Form the first The adhesive of 1 adhesive layer B is bonded to the second optical film B and the polarizer. UV rays were irradiated to harden the adhesive to form the first adhesive layer B with a thickness of 1.0 μm. The second adhesive layer B is laminated on the second optical film B. Furthermore, a third adhesive layer A is laminated on the first optical film A. In addition, when bonding each layer, corona treatment is given to the bonding surface. In this manner, a polarizing plate in which the third adhesive layer A/the first optical film A/polarizer/the first adhesive layer B/the second optical film B/the second adhesive layer B was laminated in this order was obtained.

[Comparative Example 2]

The first optical film B, the polarizer, and the second optical film C are bonded to each other through the adhesive forming the first adhesive layer C. The adhesive is dried to form the first adhesive layer C. A second adhesive layer B is laminated on the second optical film C. Furthermore, a third adhesive layer A is laminated on the first optical film B. Furthermore, when the first optical film B and the second optical film C are bonded to the polarizer, the first optical film B and the second optical film C are subjected to saponification treatment, and when the adhesive layer is laminated, corona is applied to the adhesive layer deal with. In this way, a polarizing plate in which the third adhesive layer A/first optical film B/polarizer/first adhesive layer C/second optical film C/second adhesive layer B is laminated in this order is obtained.

[High temperature durability test]

Cut the polarizing plate into a square with a size of 80mm×80mm. The cut polarizing plate was bonded to the glass plate via the second adhesive layer. A glass plate was also attached to the third adhesive layer. The glass plate is EAGLE XG (registered trademark) manufactured by Corning, and its thickness is 0.4 mm. The glass plate is larger than the polarizing plate. In this manner, a laminate for evaluation in which a pair of glass plates were layered on both areas of the polarizing plate was produced.

After leaving the evaluation laminated body in an environment with a temperature of 50 degrees for 12 hours, it was put into an oven with a temperature of 95° C. for 300 hours, or into an oven with a temperature of 105° C. for 168 hours. will The evaluation laminate was taken out of the oven, and it was visually checked whether the penetration rate of the central portion in the plane was decreased. The above results are shown in Table 1.

○: In the center of the plane, the penetration rate is not lowered

△: In the center of the plane, the penetration rate is slightly lowered

×: In the center of the plane, the penetration rate was confirmed to be significantly reduced

[High temperature and humidity durability test]

A laminate for evaluation was produced in the same manner as in the high-temperature durability test. After leaving the evaluation laminate for 12 hours in an environment with a temperature of 50 degrees, it was put into an oven at a temperature of 85° C. and a relative humidity of 85% RH for 500 hours. The evaluation laminate was taken out of the oven, and the luminescence factor of the polarizing plate was measured to correct the degree of polarization. The above results are shown in Table 1.

[Table 1]

Even if the polarizing plate of the embodiment is placed in a high temperature environment, the transmittance of the central portion in the plane is not easily reduced, and the polarization degree is not easily reduced even when placed in a high temperature and high humidity environment. another On the other hand, when the polarizing plate of Comparative Example 1 is placed in a high-temperature environment, the transmittance of the central portion in the plane decreases. When the polarizing plate of Comparative Example 2 was placed in a high-temperature and high-humidity environment, the degree of decrease in polarization was large.

[Industrial use possibility]

According to the present invention, it is possible to provide a polarizing plate which is useful because the transmittance of the central portion in the plane is not easily reduced even when placed in a high-temperature environment, and the degree of polarization is not easily reduced even when placed in a high-temperature environment.

1: Polarizer

11: The first optical film

12: The second optical film

13: The third optical film

21: The first subsequent layer

22: The second subsequent layer

23: The third subsequent layer

24: 4th subsequent layer

101, 102: Polarizing plate

Claims (6)

A polarizing plate is provided with a polarizer, a first optical film laminated on one side of the polarizer, a first adhesive layer arranged on the other side of the polarizer, and a first adhesive layer arranged on the side opposite to the polarizer side of the first adhesive layer 2 then layer; among them, The moisture permeability of the first optical film is 100g/m ² ‧24hr or less, The moisture permeability of the first adhesive layer is 500g/m ² ‧24hr or more, The moisture permeability of the second adhesive layer is 100g/m ² ‧24hr or less. The polarizing plate described in the first item of the scope of patent application has a second optical film between the first adhesive layer and the second adhesive layer, and the first adhesive layer and the second adhesive layer are in contact with the second optical film. The polarizing plate described in claim 1 or 2 includes a third adhesive layer laminated on the surface of the first optical film opposite to the polarizer side. The polarizing plate described in any one of items 1 to 3 of the scope of patent application includes a fourth adhesive layer laminated on the second adhesive layer on the opposite side to the polarizer side. A display device is a display device in which the polarizing plate described in item 3 of the scope of patent application is laminated on the front panel via the third adhesive layer, and is laminated on the display element or touch panel via the second adhesive layer. A display device in which the polarizing plate described in item 4 of the scope of patent application is laminated on the front panel via the third adhesive layer, and is laminated on the display element or touch panel via the fourth adhesive layer.

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