WO2020116074A1 - Polarizing plate and display device - Google Patents

Abstract

[Problem] The purpose of the present invention is to provide a polarizing plate which is not susceptible to decrease of the transmittance in an in-plane center part even in cases where the polarizing plate is in a high temperature environment, and which is not susceptible to decrease in the degree of polarization even in cases where the polarizing plate is in a high temperature high humidity environment. [Solution] A polarizing plate which comprises: a polarizer; a first optical film that is superposed on one surface of the polarizer; a second optical film that is superposed on the other surface of the polarizer; and a third optical film that is arranged on a surface of the first optical film, said surface being on the reverse side of the polarizer-side surface. This polarizing plate is configured such that: the first optical film and the third optical film are arranged on the viewing side on the basis of the polarizer; the water vapor permeability of the first optical film is 100 g/m2∙24 hr. or less; and the water vapor permeability of the second optical film 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.

The polarizing plate is attached between an image display device such as a liquid crystal cell or an organic EL device and a transparent plate such as a front plate or a touch panel via an adhesive layer, and is used in various liquid crystal display devices or organic EL display devices. Used in image display devices. In recent years, such an image display device may be used as an in-vehicle image display device such as a car navigation device or a back monitor in addition to a mobile device such as a mobile phone or a tablet terminal. Along with this, the polarizing plate is required to have durability in a more severe environment than conventionally required (Patent Document 1).

Patent Document 1 describes a laminated body in which glass plates are laminated on both sides of a polarizing plate via an adhesive layer, and the amount of water per unit area of the polarizing plate and a transparent protective film constituting the polarizing plate. It is described that the saturated water supply amount of each is set to a predetermined value or less. Patent Document 1 discloses that even when the laminate is placed in a high temperature environment (temperature: 95° C.), the transmittance of the in-plane central portion of the polarizing plate does not easily decrease.

JP, 2014-102353, A

The polarizing plate described in Patent Document 1 has an effect of preventing the transmittance of the central portion of the polarizing plate from decreasing in a high temperature environment. However, the effect was not always satisfactory. In addition, the polarizing plate described in Patent Document 1 has a problem that the degree of polarization tends to decrease in a high temperature and high humidity environment.

The object of the present invention is that the transmittance of the in-plane central portion is unlikely to decrease even when placed in a high temperature environment, and the polarization degree is less likely to decrease even when placed in a high temperature and high humidity environment. It is to provide a polarizing plate.

[1] A polarizer, a first optical film laminated on one surface of the polarizer, a second optical film laminated on the other surface of the polarizer, and a polarizer side of the first optical film. And a third optical film disposed on the side opposite to,
The first optical film and the third optical film are films arranged on the viewing side based on the polarizer,
The water vapor transmission rate of the first optical film is 100 g/m ² ·24 hr. Is less than
The water vapor permeability of the second optical film is 100 g/m ² ·24 hr. The following is a polarizing plate.
[2] A first adhesive layer is provided between the first optical film and the third optical film,
The first optical film and the third optical film are the polarizing plates described in [1], which are in contact with the first adhesive layer.
[3] The water vapor transmission rate of the first adhesive layer is 500 g/m ² ·24 hr. The polarizing plate described in [1] or [2] above.
[4] A second adhesive layer laminated on the surface of the second optical film opposite to the polarizer side,
The polarizing plate according to any one of [1] to [3], further including a third adhesive layer laminated on a surface of the third optical film opposite to the polarizer side.
[5] A display device in which the polarizing plate described in [4] is laminated on a front plate via a third adhesive layer and laminated on a display element via a second adhesive layer.

According to the present invention, the transmittance of the in-plane central portion is unlikely to decrease even when placed in a high temperature environment, and the polarization degree is less likely to decrease even when placed in a high temperature and high humidity environment. A polarizing plate can be provided.

It is an example of a schematic cross-sectional view showing a layer structure of a polarizing plate. It is an example of a schematic cross-sectional view showing a layer structure of a display device.

<Polarizing plate>
The polarizing plate of the present invention includes a polarizer, a first optical film laminated on one surface of the polarizer, a second optical film laminated on the other surface of the polarizer, and a first optical film. And a third optical film arranged on the side opposite to the polarizer side. The first optical film and the third optical film are films arranged on the viewing side with respect to the polarizer.

An example of the layer structure of the polarizing plate of the present invention will be specifically described with reference to FIG. The polarizing plate 101 shown in FIG. 1 includes a polarizer 1, a first optical film 11 laminated on one surface of the polarizer 1, and a second optical film 12 laminated on the other surface of the polarizer 1. And a third optical film 13 arranged on the side of the first optical film 11 opposite to the polarizer 1 side. The polarizing plate 101 has a first adhesive layer 21 between the first optical film 11 and the third optical film 13, and the first optical film 11 and the third optical film 13 have the first adhesive layer 21. It is in contact with the adhesive layer 21. That is, the first optical film 11 and the third optical film 13 are laminated via the first adhesive layer 21. The polarizing plate 101 includes a second adhesive layer 22 laminated on a surface of the second optical film 12 opposite to the polarizer 1 side and a second adhesive layer 22 of the third optical film 13 opposite to the polarizer 1 side. And a third adhesive layer 23 laminated on the surface.

In this embodiment, the third adhesive layer 23 can be an adhesive layer for attaching to a front plate or a touch panel, and the second adhesive layer 22 can be an adhesive layer for attaching to a touch panel or a display element. It can be a layer.

The water vapor transmission rate of the first optical film 11 is 100 g/m ² ·24 hr. Or less, and 50 g/m ² ·24 hr. It is preferably not more than 20 g/m ² ·24 hr. The following is more preferable. The water vapor transmission rate of the first optical film 11 is 0 g/m ² ·24 hr. Can be more.

In the present specification, the water vapor transmission rate refers to a value measured under the conditions of a temperature of 40° C. and a relative humidity of 90% in accordance with JIS Z 0208 (cup method).

The water vapor permeability of the second optical film 12 is 100 g/m ² ·24 hr. Or less, and 50 g/m ² ·24 hr. It is preferably not more than 20 g/m ² ·24 hr. The following is more preferable. The water vapor transmission rate of the second optical film 12 is 0 g/m ² ·24 hr. Can be more.

The water vapor permeability of the third optical film 13 is 500 g/m ² ·24 hr. It is preferably not more than 200 g/m ² ·24 hr. It is more preferably not more than 50 g/m ² ·24 hr. The following is more preferable. The moisture permeability of the third optical film 13 is 0 g/m ² ·24 hr. Can be more.

The third optical film 13, the first optical film 11, the polarizer 1, and the second optical film 12 are laminated in this order from the viewing side, and the first optical film 11 and the second optical film 12 are respectively the above-mentioned. By indicating the range of water vapor transmission rate, the transmittance of the center of the surface does not easily decrease even when placed in a high temperature environment, and the polarization degree is exhibited even when placed in a high temperature and high humidity environment. Is less likely to decrease.

In the display device including the polarizing plate having the above configuration, the distance between the polarizer 1 and the front plate is long.
When such a display device is placed in a high temperature environment, the water content in the polarizer 1 is likely to escape to the outside of the polarizer, and the water content is unlikely to remain in the polarizer 1. In addition, when the first optical film 11 and the second optical film 12 exhibit the above-mentioned moisture permeability, since the water content of them is small, the water content in the polarizing plate can be made small. Further, the polarizing plate in which the first optical film 11 and the second optical film 12 have the above-mentioned moisture permeability can prevent moisture from entering the polarizer 11 from the outside under a high temperature and high humidity environment.

The distance from the surface of the polarizer 1 on the first optical film 11 side to the surface of the third optical film 13 on the side opposite to the polarizer 1 side is preferably 25 μm or more, and 50 μm or more. Is more preferable, and may be 130 μm or less. When the polarizing plate has the third adhesive layer 23, the distance from the surface of the polarizer 1 on the first optical film 11 side to the surface of the third adhesive layer 23 on the side opposite to the polarizer 1 side is It is preferably 35 μm or more, more preferably 80 μm or more, and may be 330 μm or less.

From the viewpoint of ensuring the distance between the polarizer 1 and the front plate, the thickness of the first optical film 11 is preferably 10 μm or more, preferably 20 μm or more, and even 50 μm or less. Good. Similarly, the thickness of the third optical film 13 is preferably 10 μm or more, preferably 20 μm or more, and may be 50 μm or less.

Between the first optical film 11 and the third optical film 13, it is preferable to arrange a layer having a high moisture permeability or a layer having a certain thickness. It is preferable that the first adhesive layer 21 is disposed between the first optical film 11 and the third optical film 13, and the first optical film 11 and the third optical film 13 have the first adhesive layer 21. It is preferably in contact with the layer 21.

The water vapor transmission rate 21 of the first adhesive layer is 500 g/m ² ·24 hr. It is preferably not less than 1000 g/m ² ·24 hr. The above is more preferable. The water vapor transmission rate of the first adhesive layer 21 is 5000 g/m ² ·24 hr. It can be:

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

The polarizing plate can have layers other than the layers shown in FIG. Examples of the layer that the polarizing plate may further include include a front plate, a light-shielding pattern, a retardation film, and a brightness enhancement film. The front plate can be arranged on the viewing side of the polarizing plate.

The light-shielding pattern can be formed on the polarizing plate side surface of the front plate, the front plate side surface of the polarizing plate, or both. The light-shielding pattern can be formed in the frame (non-display area) of the display device so that the wiring of the display device is not visible to the user.

The retardation film can be arranged between the second adhesive layer and the polarizer or between the third adhesive layer and the polarizer. Further, at least one selected from the group consisting of the first optical film, the second optical film, and the third optical film may have a function as a retardation film.

The shape of the main surface of the polarizing plate can be circular, polygonal, other figures, and combinations thereof. The main surface of the polarizing plate may have a substantially rectangular shape. The main surface means a surface having the largest area corresponding to the display surface. The term “substantially rectangular” means that at least one corner of the four corners (corner) is cut off so that it has an obtuse angle, is rounded, or has an end surface perpendicular to the main surface. Part of the main surface has a recessed part (notch) that is recessed in the in-plane direction, or part of the main surface has a perforated part that is cut into a shape such as a circle, an ellipse, a polygon, or a combination thereof. It means that you may have. When the polarizing plate is for vehicle use, the shape of the main surface of the polarizing plate may be the shape of a side mirror, the shape of a rearview mirror or the shape of an instrument panel.

The size of the polarizing plate fits in a rectangle having a long side of 6 cm or more and 35 cm or less and a short side of 5 cm or more and 30 cm or less, from the viewpoint of further reducing the decrease in the transmittance in the in-plane central portion. It is preferably a size, and more preferably a size that fits in a rectangle having a long side of 10 cm or more and 30 cm or less and a short side of 6 cm or more and 25 cm or less.

Hereinafter, each layer included in the polarizing plate will be described.
(1) Polarizer A polarizer included in a polarizing plate absorbs linearly polarized light having a vibration plane parallel to its absorption axis, and transmits linearly polarized light having a vibration plane orthogonal to the absorption axis (parallel to the transmission axis). It can be an absorption-type polarizer having properties.

The water content of the polarizer is preferably less than 8% by weight, more preferably 6% by weight or less, and further preferably 5% by weight or less. The water content of the polarizer is usually 0% by weight or more, and may be 1% by weight or more. When the water content of the polarizer is within the above range, it becomes difficult for the water to be retained, and even when the glass plates are laminated on both surfaces of the polarizing plate with the pressure-sensitive adhesive layer in the high temperature environment, The transmittance of the central part is less likely to decrease.

The water content of the polarizer may easily fluctuate when an optical film or a moisture-proof film is not attached or temporarily attached to both surfaces of the polarizer. Therefore, in the present invention, the water content of the polarizer may be the water content immediately before bonding when two optical films (the first optical film and the second optical film) are bonded at the same time. In the case where the two optical films are sequentially laminated, the water content immediately before the second optical film is laminated can be used.
By adopting such a water content, the above problems can be easily solved.

The water content of the polarizer is measured as follows. A calibration curve showing the relationship between the moisture content measured by a near infrared moisture content meter (“IRMA1100S” manufactured by Chinault Co., Ltd.) and the moisture content obtained by the dry weight method by a linear equation is shown in a plurality of different moisture content It is obtained in advance from both moisture contents obtained for the polarizer sample of. The moisture content measured by the near infrared moisture content meter is converted into the moisture content by the dry weight method using the above calibration curve, and this is defined as the moisture content of the polarizer. The water content by the dry weight method is expressed by the following formula, where W0 is the weight of the sample before drying and W1 is the weight when the sample is dried at 105° C. for 1 hour.
Moisture content (% by weight)=100×(W0-W1)/W0
Is defined by

As the polarizer, a polarizer in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol-based resin film can be preferably used. The polarizer is, for example, a step of uniaxially stretching a polyvinyl alcohol-based resin film; a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye; a polyvinyl dye-adsorbed polyvinyl It can be produced by a method including a step of treating the alcohol-based resin film with a cross-linking solution such as a boric acid aqueous solution; and a step of washing after the treatment with the cross-linking solution.

As the polyvinyl alcohol resin, saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers with other monomers copolymerizable with 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 this specification, “(meth)acrylic” means at least one selected from acrylic and methacrylic. The same applies to “(meth)acryloyl”, “(meth)acrylate” and the like.

The saponification degree of the polyvinyl alcohol resin is usually 85 to 100 mol %, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The average degree of polymerization of the polyvinyl alcohol resin is usually 1,000 to 10,000, preferably 1,500 to 5,000. The average degree of polymerization of the polyvinyl alcohol resin can be determined according to JIS K 6726.

A film made of such a polyvinyl alcohol resin is used as a raw film for a polarizer (polarizer). The method for forming the polyvinyl alcohol-based resin is not particularly limited, and a known method is adopted. The thickness of the polyvinyl alcohol-based raw film is not particularly limited, but in order to make the thickness of the polarizer 15 μm or less, it is preferable to use one having a thickness of 5 to 35 μm. More preferably, it is 20 μm or less.

The uniaxial stretching of the polyvinyl alcohol resin film can be performed before, at the same time as, or after the dyeing of the dichroic dye. When the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before or during the crosslinking treatment. In addition, uniaxial stretching may be performed at these plural stages.

When uniaxially stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a heat roll. The uniaxial stretching may be dry stretching in which the stretching is performed in the atmosphere, or wet stretching in which the polyvinyl alcohol-based resin film is swollen with a solvent or water. The draw ratio is usually 3 to 6 times.

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

As a cross-linking treatment after dyeing with a dichroic dye, a method of immersing the dyed polyvinyl alcohol resin film in a boric acid-containing aqueous solution is usually adopted. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide.

After the cross-linking treatment, washing and draining are preferable. The cleaning treatment can be performed by immersing the film after the crosslinking treatment in ion-exchanged water, pure water such as distilled water, or an aqueous potassium iodide solution. The temperature of water (or aqueous solution) used for washing is preferably 1 to 10°C, and more preferably 1 to 5°C. The draining treatment can be performed by blowing off the water (or the aqueous solution) attached to the surface of the film with an air knife or an air blower or sucking it with a sponge. By using water (or an aqueous solution) at the above temperature for washing and draining water, a polarizer whose transmittance at the center of the plane does not easily decrease even when placed in a high temperature environment is obtained. be able to.

After cleaning, it is preferable to carry out a drying process. As the drying performed after washing, any suitable method such as natural drying, blast drying, and heat drying can be adopted. For example, in the case of heat drying, the maximum drying temperature is preferably 70 to 95° C., and the drying time is preferably 1 to 15 minutes.

The thickness of the polarizer is preferably 10 μm or less, more 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 reduce the amount of water contained in the polarizer, and it is easy to prevent the transmittance of the in-plane central portion from decreasing. In addition, as the thickness of the polarizer becomes smaller, the concentration of iodine becomes higher, and the concentration of iodine complex existing near the interface with the optical films laminated on both sides also becomes higher. It is easy to receive. Therefore, the smaller the thickness of the iodine-based polarizer 5 is, the lower the resistance to moist heat tends to be. In addition, when the thickness of the polarizer is reduced and the concentration of iodine is increased, the moisture remaining in the polarizer is more likely to affect the heat resistance. As described above, the smaller the thickness of the polarizer, the lower the heat and humidity resistance tends to be, and the present invention is particularly advantageous when the thickness of the polarizer is small.

As the polarizer, for example, as described in JP-A-2016-170368, a cured film in which a liquid crystal compound is polymerized and a dichroic dye is aligned may be used. As the dichroic dye, those having absorption in the wavelength range of 380 to 800 nm can be used, and organic dyes are preferably used. Examples of dichroic dyes include azo compounds.
The liquid crystal compound is a liquid crystal compound that can be polymerized while being aligned, and can have a polymerizable group in its molecule. Further, as described in WO2011/024891, a polarizer may be formed from a dichroic dye having liquid crystallinity.

(2) First to Third Optical Films The first to third optical films may be collectively referred to as an optical film. The optical film can be a resin film. The optical film can be a protective film having a function of protecting the polarizer. The optical film can also be a retardation film having a retardation.

The protective film is a translucent (preferably optically transparent) thermoplastic resin, for example, a polyolefin such as a chain polyolefin resin (polypropylene resin or the like) or a cyclic polyolefin resin (norbornene resin or the like). -Based resins; cellulose-based resins such as triacetyl cellulose and diacetyl cellulose; polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate-based resins; (meth)acrylic-based resins such as methyl methacrylate-based resins; polystyrene-based resins Resin; Polyvinyl chloride resin; Acrylonitrile-butadiene-styrene resin; Acrylonitrile-styrene resin; Polyvinyl acetate resin; Polyvinylidene chloride resin; Polyamide resin; Polyacetal resin; Modified polyphenylene ether resin; Polysulfone resin The film may be a resin; a polyether sulfone resin; a polyarylate resin; a polyamideimide resin; a polyimide resin or the like. In the present invention, the protective film is preferably a film made of a polyolefin resin or a (meth)acrylic resin.

As the chain polyolefin resin, polyethylene resin (polyethylene resin which is a homopolymer of ethylene or a copolymer mainly composed of ethylene), polypropylene resin (a polypropylene resin which is a homopolymer of propylene or propylene is mainly used) In addition to a chain olefin homopolymer such as a copolymer), a copolymer composed of two or more kinds of chain olefins can be mentioned.

Cyclic polyolefin resin is a general term for resins polymerized with cyclic olefin as a polymerized unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, and JP-A-3-122137. Resins. Specific examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins with chain olefins such as ethylene and propylene (typically Are random copolymers), graft polymers obtained by modifying these with unsaturated carboxylic acids or their derivatives, and their hydrides. Among them, norbornene-based resins using norbornene-based monomers such as norbornene and polycyclic norbornene-based monomers as the cyclic olefin are preferably used.

The polyester-based resin is a resin having an ester bond other than the following cellulose ester-based resins, and is generally composed of a polycondensate of a polyvalent carboxylic acid or its derivative and a polyhydric alcohol. As the polyvalent 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 naphthalenedicarboxylate. A divalent diol can be used as the polyhydric alcohol, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A typical example of the polyester resin is polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

The (meth)acrylic resin is a resin containing a compound having a (meth)acryloyl group as a main constituent monomer. Specific examples of the (meth)acrylic resin include, for example, poly(meth)acrylic acid ester such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymer; methyl methacrylate-(meth)acrylic acid. Ester copolymer; methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymer; methyl (meth)acrylate-styrene copolymer (MS resin etc.); methyl methacrylate and alicyclic hydrocarbon group And a copolymer with a compound having such a compound (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). Preferably, a polymer having a poly(meth)acrylic acid C _1-6 alkyl ester as a main component such as methyl poly(meth)acrylate is used, and more preferably, methyl methacrylate is a main component (50 to 100). %, preferably 70 to 100% by weight) methyl methacrylate resin is used.

Cellulose ester resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Moreover, these copolymers and those in which a part of the hydroxyl groups are modified with other substituents are also included. Among these, cellulose triacetate (triacetyl cellulose) is particularly preferable.

Polycarbonate resin is an engineering plastic made of a polymer in which monomer units are bonded via a carbonate group.

The protective film has a surface such as a hard coat layer, an antiglare layer, a light diffusion layer, an antireflection layer, a low refractive index layer, an antistatic layer and an antifouling layer on the outer surface (the surface opposite to the polarizer). It may include a treatment layer (coating layer). The thicknesses of the first to third optical films include the thickness of the surface treatment layer. The protective film may have a retardation value.

When the film is a thermoplastic resin film, the thickness of the optical film is usually 10 to 100 μm, but from the viewpoint of imparting moisture permeability in a predetermined range, it is preferably 10 to 60 μm and 10 to 55 μm. More preferably, it is more preferably 15 to 40 μm.

The first and second optical films can be attached to the polarizer via an adhesive layer, for example. Note that, in FIGS. 1 and 2, the adhesive layer for bonding the first and second optical films and the polarizer is omitted. The third optical film can be attached to the first optical film via an adhesive layer or a pressure-sensitive adhesive layer, for example, and can be attached to the first optical film via the first adhesive layer. be able to. The first adhesive layer will be described later. As the adhesive forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive or a thermosetting adhesive can be used, and preferably a water-based adhesive or an active energy ray-curable adhesive.

Examples of the water-based adhesive include an adhesive composed of a polyvinyl alcohol-based resin aqueous solution and a water-based two-component urethane-based emulsion adhesive. Above all, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is preferably used. Examples of the polyvinyl alcohol-based resin include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate and other monomers copolymerizable therewith. A polyvinyl alcohol-based copolymer obtained by saponifying a polymer, a modified polyvinyl alcohol-based polymer obtained by partially modifying a hydroxyl group thereof, or the like can be used. The water-based adhesive may contain a crosslinking agent such as an aldehyde compound (glyoxal or the like), an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound, a polyvalent metal salt or the like.

When a water-based adhesive is used, after the polarizer and the first to second optical films are bonded or the first optical film and the third optical film are bonded, It is preferable to carry out a drying step for removing the water contained in. After the drying step, a curing step of curing at a temperature of 20 to 45° C., for example, may be provided.

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

The above-mentioned curable compound can be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of the cationically polymerizable curable compound include epoxy compounds (compounds having one or more epoxy groups in the molecule) and oxetane compounds (one or more oxetane rings in the molecule). Or a combination thereof. Examples of the radical-polymerizable curable compound include a (meth)acrylic compound (compound having one or more (meth)acryloyloxy groups in the molecule) and a radical-polymerizable double bond. Other vinyl compounds or combinations thereof may be mentioned. You may use together a cationically polymerizable curable compound and a radically polymerizable curable compound. The active energy ray-curable adhesive usually further contains a cationic polymerization initiator and/or a radical polymerization initiator for initiating a curing reaction of the curable compound.

At least one of these in order to improve the adhesiveness in bonding the polarizer and the first optical film or the second optical film, or in bonding the first optical film and the third optical film. One of the bonding surfaces may be subjected to surface activation treatment. As surface activation treatment, dry treatment such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionizing actinic ray treatment (ultraviolet treatment, electron beam treatment, etc.) Ultrasonic treatment using a solvent such as water or acetone, saponification treatment, wet treatment such as anchor coating treatment can be mentioned. These surface activation treatments may be performed alone or in combination of two or more.

As the optical film, a retardation film can be exemplified. The retardation film is a film including at least a retardation layer. The retardation film may be a film including two retardation layers. When the retardation film has two retardation layers, the two retardation layers may be a combination of a layer giving a retardation of λ/4 and a positive C layer, or a layer giving a retardation of λ/4 and a λ. A combination of layers that gives a retardation of /2 is preferable.

The retardation layer may be a stretched film, and the material of the stretched film is selected from those exemplified for the resin forming the above-mentioned protective film. In this case, the retardation layer can be a stretched film made of a polyolefin resin or a polycarbonate resin. The retardation layer may be a layer composed of a composition containing a polymerizable liquid crystal compound. The layer composed of the composition containing the polymerizable liquid crystal compound specifically means a layer in which the polymerizable liquid crystal compound is cured. In this specification, a layer that gives a retardation of λ/2, a layer that gives a retardation of λ/4 (a positive A layer), a positive C layer, and the like may be collectively referred to as a retardation layer. Further, the retardation film may include an alignment film described later.

The layer giving a retardation of λ/2 means a layer having an in-plane retardation value of 200 to 280 nm at a wavelength of 550 nm, and more preferably a layer having an in-plane retardation value of 215 to 265 nm. Means that. The layer giving a retardation of λ/4 means a layer having an in-plane retardation value of 100 to 160 nm at a wavelength of 550 nm, and more preferably a layer having an in-plane retardation value of 110 to 150 nm. Means that. The positive C layer can be a layer in which the refractive index has a relationship of nx≈ny<nz. The retardation value in the thickness direction of the positive C layer can be −50 nm to −150 nm at a wavelength of 550 nm, and can be −70 nm to −120 nm. The retardation layer may exhibit positive wavelength dispersion or reverse wavelength dispersion.

In particular, when the second optical film includes a layer giving a retardation of λ/4, the second optical film has an angle between the slow axis of the layer giving a retardation of λ/4 and the absorption axis of the polarizer. It can be laminated so as to form an angle of about 45°. About 45° means 40° to 50°. At this time, the polarizing plate may have a function as a circularly polarizing plate.

The layer in which the polymerizable liquid crystal compound is cured is formed, for example, on the alignment film provided on the base material. The base material may have a function of supporting the alignment film and may be a long base material. This substrate functions as a releasable support and can support a retardation layer for transfer. Further, it is preferable that the surface thereof has an adhesive strength such that it can be peeled off. Examples of the substrate include the resin films exemplified as the material for the protective film.

The layer in which the polymerizable liquid crystal compound is cured is formed on the base material via the alignment film. That is, the base material and the alignment film are laminated in this order, and the layer in which the polymerizable liquid crystal compound is cured is laminated on the alignment film.

Note that the alignment film is not limited to the vertical alignment film, and may be an alignment film that horizontally aligns the molecular axes of the polymerizable liquid crystal compound or an alignment film that tilts the molecular axes of the polymerizable liquid crystal compound. .. The thickness of the alignment film is usually 10 nm to 10000 nm, preferably 10 nm to 1000 nm, more preferably 500 nm or less, and further preferably 10 nm to 200 nm.

The type of the polymerizable liquid crystal compound used in the present embodiment is not particularly limited, but is classified into a rod-shaped type (rod-shaped liquid crystal compound) and a disc-shaped type (disc-shaped liquid crystal compound, discotic liquid crystal compound) based on the shape. it can. Further, there are low molecular type and high molecular type respectively. The term "polymer" generally means a polymer having a degree of polymerization of 100 or more (polymer physics/phase transition dynamics, Masao Doi, page 2, Iwanami Shoten, 1992).

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

As the rod-shaped liquid crystal compound, for example, those described in claim 1 of JP-A-11-513019 or paragraphs [0026] to [0098] of JP-A-2005-289980 are preferably used. You can As the discotic liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP2007-108732A, or paragraphs [0013] to [0108] of JP2010-244038A are preferable. Can be used for.

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

The polymerizable liquid crystal compound has a polymerizable group capable of undergoing a polymerization reaction. As the polymerizable group, for example, a functional group capable of addition polymerization reaction such as a polymerizable ethylenically unsaturated group or a ring-polymerizable group is preferable. More specifically, examples of the polymerizable group include a (meth)acryloyl group, a vinyl group, a styryl group, and an allyl group. Of these, a (meth)acryloyl group is preferable. The (meth)acryloyl group is a concept that includes both a methacryloyl group and an acryloyl group.

The layer in which the polymerizable liquid crystal compound is cured can be formed by applying a composition containing the polymerizable liquid crystal compound onto, for example, an alignment film and irradiating with active energy rays such as ultraviolet rays. Components other than the above-mentioned polymerizable liquid crystal compound may be added to the composition.
For example, the composition preferably contains a polymerization initiator. As the polymerization initiator, for example, a thermal polymerization initiator or a photopolymerization initiator is selected according to the type of polymerization reaction. Examples of the photopolymerization initiator include an α-carbonyl compound, an acyloin ether, an α-hydrocarbon-substituted aromatic acyloin compound, a polynuclear quinone compound, and a combination of a triarylimidazole dimer and p-aminophenyl ketone. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, and more preferably 0.5 to 5% by mass, based on the total solid content in the composition.

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

The polymerizable monomer 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, more preferably 2 to 30% by mass, based on the total mass of the polymerizable liquid crystal compound.

The composition may contain a surfactant from the viewpoint of uniformity of the coating film and strength of the film. Examples of the surfactant include conventionally known compounds. Of these, fluorine compounds are particularly preferable.

The composition may include a solvent. An organic solvent is preferably used as the solvent. Examples of the organic solvent include amides (N,N-dimethylformamide, etc.), sulfoxides (dimethylsulfoxide, etc.), 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.). Of these, alkyl halides and ketones are preferable. Also, two or more kinds of organic solvents may be used in combination.

The composition has various alignments such as a vertical alignment promoter such as a polarizer interface side vertical alignment agent and an air interface side vertical alignment agent, and a horizontal alignment promoter such as a polarizer interface side horizontal alignment agent and an air interface side horizontal alignment agent. The agent may be included. The composition may contain an adhesion improver, a plasticizer, a polymer and the like in addition to the above components.

When the optical film is a retardation film, the thickness of the optical film is preferably 0.5 μm or more. Further, the thickness of the optical film is preferably 30 μm or less, and more preferably 25 μm or less. When the thickness of the retardation film is at least the above lower limit value, sufficient durability can be obtained. When the thickness of the retardation film is not more than the above upper limit value, it can contribute to the thinning of the polarizing plate. With respect to the thickness of each retardation layer, a desired in-plane retardation value of a layer giving a retardation of λ/4, a layer giving a retardation of λ/2, or a positive C layer, and a retardation value in the thickness direction can be obtained. Can be adjusted.

The materials and thicknesses for forming the first to third optical films may be the same or different from each other. It is preferable that each of the first to third optical films contains a thermoplastic resin film because the moisture permeability can be easily controlled. Each of the first to third optical films may be a laminate of a plurality of thermoplastic resin films, but preferably each is a single layer of thermoplastic resin film.

(5) First to third adhesive layers The first to third adhesive layers may be collectively referred to as an adhesive layer. The adhesive layer is formed of an adhesive layer and a pressure-sensitive adhesive layer. It is preferable that all of the first to third adhesive layers are pressure-sensitive adhesive layers. The first adhesive layer can have a function of laminating the above-mentioned first optical film and third optical film. The second adhesive layer can be for bonding the polarizing plate to a display element or a touch panel. The third adhesive layer can be for bonding the polarizing plate to the front plate or the touch panel.

The adhesive layer may be a layer formed from a water-based adhesive or an active energy ray-curable adhesive, that is, a water-based adhesive layer or an active energy ray-curable adhesive layer. A water-based adhesive layer is preferable as the adhesive layer forming the first adhesive layer because the water vapor permeability can be easily controlled within the above range.

Examples of the water-based adhesive include an adhesive composed of a polyvinyl alcohol-based resin aqueous solution and a water-based two-component urethane-based emulsion adhesive. Above all, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is preferably used. Examples of the polyvinyl alcohol-based resin include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. A polyvinyl alcohol-based copolymer obtained by saponifying a polymer, or a modified polyvinyl alcohol-based polymer obtained by partially modifying the hydroxyl groups thereof can be used. The water-based adhesive may contain a crosslinking agent such as an aldehyde compound (glyoxal or the like), an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound, a polyvalent metal salt or the like. The thickness of the water-based adhesive layer can be 1 μm or less.

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

The above-mentioned curable compound can be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of the cationically polymerizable curable compound include epoxy compounds (compounds having one or more epoxy groups in the molecule) and oxetane compounds (one or more oxetane rings in the molecule). Or a combination thereof. Examples of the radical-polymerizable curable compound include a (meth)acrylic compound (compound having one or more (meth)acryloyloxy groups in the molecule) and a radical-polymerizable double bond. Other vinyl compounds or combinations thereof may be mentioned. You may use together a cationically polymerizable curable compound and a radically polymerizable curable compound. The active energy ray-curable adhesive usually further contains a cationic polymerization initiator and/or a radical polymerization initiator for initiating a curing reaction of the curable compound. The thickness of the active energy ray-curable adhesive layer can be 0.5 μm or more and 2 μm or less.

The adhesive layer can also be formed from an adhesive layer. The pressure-sensitive adhesive layer can be composed of a pressure-sensitive adhesive composition containing a resin such as a (meth)acrylic resin, a urethane resin, an ester resin, a silicone resin, or a polyvinyl ether resin as a main component. Above all, a pressure-sensitive adhesive composition containing a (meth)acrylic resin as a base polymer is preferable because the moisture permeability can be easily controlled. The pressure-sensitive adhesive composition may be an active energy ray curable type or a thermosetting type.

Examples of the (meth)acrylic resin (base polymer) used in the pressure-sensitive adhesive composition include butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-(meth)acrylic acid. A polymer or copolymer having one or more (meth)acrylic acid ester monomers such as ethylhexyl as a monomer is preferably used. It is preferable to copolymerize a polar monomer with the base polymer. Examples of polar monomers include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, glycidyl ( Examples thereof include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like such as (meth)acrylate.

The pressure-sensitive adhesive composition may contain only the above base polymer, but usually further contains a crosslinking agent. As the cross-linking agent, a metal ion having a valence of 2 or more and forming a carboxylic acid metal salt with a carboxyl group; a polyamine compound forming an amide bond with a carboxyl group; Examples thereof include epoxy compounds and polyols that form an ester bond with a carboxyl group; and polyisocyanate compounds that form an amide bond with a carboxyl group. Of these, polyisocyanate compounds are preferable.

When a pressure-sensitive adhesive layer is used as the first adhesive layer, the thickness of the pressure-sensitive adhesive layer is preferably 5 μm or more and 30 μm or less, and more preferably 5 μm or more and 25 μm or less. From the viewpoint of further reducing the decrease in the transmittance at the in-plane central portion, when a pressure-sensitive adhesive layer is adopted as the second adhesive layer and the third adhesive layer, the thickness of each pressure-sensitive adhesive layer is 10 μm or more. The thickness is preferably 15 μm or more, more preferably 30 μm or more. The thickness of the second pressure-sensitive adhesive layer and the third pressure-sensitive adhesive layer is preferably 200 μm or less, and more preferably 150 μm or less.

The materials and thicknesses of the first to third adhesive layers may be the same or different from each other.

<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, or a plasma display device.

An example of the layer structure of the display device of the present invention will be specifically described with reference to FIG. In the display device 201 shown in FIG. 2, the polarizing plate 101 shown in FIG. 1 is laminated on the front plate 31 via the third adhesive layer 23 and laminated on the display element 32 via the second adhesive layer 22. Display device. Although not shown, one of the front plate and the display element may be replaced with a touch panel.

(1) Front Plate The front plate is arranged on the viewing side of the polarizing plate. The front plate can be laminated on the polarizing plate via a third adhesive layer.

The front plate may be glass or a resin film having a hard coat layer on at least one surface. As the glass, for example, high transmission glass or tempered glass can be used. Especially when a thin transparent surface material is used, chemically strengthened glass is preferable. The thickness of the glass may be, for example, 100 μm to 5 mm.

The front plate, which has a hard coat layer on at least one side of the resin film, is not rigid like existing glass and can have flexible characteristics. The thickness of the hard coat layer is not particularly limited and may be, for example, 5 to 100 μm.

As the resin film, a cycloolefin derivative having a unit of a cycloolefin-containing monomer such as norbornene or a polycyclic norbornene monomer, cellulose (diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl ester cellulose) , Propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose) ethylene-vinyl acetate copolymer, polycycloolefin, polyester, polystyrene, polyamide, polyetherimide, polyacryl, polyimide, polyamideimide, polyethersulfone, polysulfone, polyethylene, Polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate It may be a film formed of a polymer such as polyurethane, epoxy, or the like. As the resin film, an unstretched, uniaxially or biaxially stretched film can be used. These polymers can be used alone or in admixture of two or more. As the resin film, a polyamide imide film or a polyimide film having excellent transparency and heat resistance, a uniaxially or biaxially stretched polyester film, a cycloolefin derivative film having excellent transparency and heat resistance and capable of responding to an increase in size of the film Polymethylmethacrylate film and triacetyl cellulose and isobutyl ester cellulose film having transparency and no optical anisotropy are preferable. The thickness of the resin film may be 5 to 200 μm, preferably 20 to 100 μm.

The hard coat layer can be formed by curing a hard coat composition containing a reactive material that forms a crosslinked structure by irradiation with light or heat energy. The hard coat layer can be formed by curing a hard coat composition containing a photocurable (meth)acrylate monomer, or an oligomer and a photocurable epoxy monomer, or an oligomer at the same time. The photo-curable (meth)acrylate monomer may include at least one selected from the group consisting of epoxy (meth)acrylate, urethane (meth)acrylate and polyester (meth)acrylate. Epoxy (meth)acrylate can be obtained by reacting an epoxy compound with a carboxylic acid having a (meth)acryloyl group.

The hard coat composition may further include one or more selected from the group consisting of a solvent, a photoinitiator and an additive. The additive may include one or more selected from the group consisting of inorganic nanoparticles, a leveling agent, and a stabilizer. Other than that, as each component commonly used in the art, for example, It may further include an oxidizing agent, a UV absorber, a surfactant, a lubricant, an antifouling agent, and the like.

(2) Light-shielding pattern The light-shielding pattern can be provided as at least a part of the bezel or housing of the front plate or the display device to which the front plate is applied. The light-shielding pattern can be formed on the surface of the front plate on the polarizing plate side, on the surface of the polarizing plate on the front plate side, or both. The light-shielding pattern can hide each wiring of the display device so as not to be visually recognized by the user.
The color and/or material of the light-shielding pattern is not particularly limited, and can be formed of resin materials having 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, and more preferably 6 μm to 15 μm. Further, in order to prevent bubbles from entering due to a step between the light-shielding pattern and the display portion and visual recognition of the boundary portion, a shape can be given to the light-shielding pattern.

(3) Display Element As the display element, a liquid crystal display element, an organic EL display element, an inorganic EL display element, a plasma display element, or the like can be mentioned. Specifically, for example, the liquid crystal display element is configured to include a first substrate and a second substrate. The first substrate is a thin film transistor substrate having a plurality of thin film transistors (TFTs) formed in a matrix. The second substrate is a counter substrate which is arranged so as to face 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 electrodes facing each other. Electrons are injected into this organic light emitting material layer from one electrode and holes are injected from the other electrode, so that electrons and holes are combined in the organic light emitting material layer to perform self-light emission. Compared with a liquid crystal display device or the like that requires a backlight, it has advantages that it has good visibility, can be made thinner, and can be driven at a low DC voltage.

(4) Touch Panel The touch panel has a base material, a lower electrode provided on the base material, an upper electrode facing the lower electrode, and an insulating layer sandwiched between the lower electrode and the upper electrode. As the base material, various materials can be used as long as it is a flexible resin film having a light-transmitting property. For example, as the substrate, the film exemplified as the material of the above-mentioned first optical film can be used.

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

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

　The insulating layer insulates the lower and upper electrodes. As a material for forming the insulating layer, a material generally known as a material for the insulating layer of the touch panel can be used.

In the present embodiment, the touch panel is described as being a so-called projected capacitive touch sensor, but a touch panel of another type such as a film resistance type is adopted as long as the effect of the invention is not impaired. You can also do it.

<Production method of polarizing plate>
A method of manufacturing a polarizing plate will be described by taking the polarizing plate 101 shown in FIG. 1 as an example. The polarizing plate 101 is a step of bonding the polarizer 1 and the first optical film 11 with an adhesive, and a step of bonding the polarizer 1 and the second optical film 12 with an adhesive. , A step of laminating the first adhesive layer 21 on the first optical film 11, a step of laminating the third optical film 13 on the first adhesive layer 21, a second adhesive layer on the second optical film 12. It is obtained from the step of laminating the third adhesive layer 23 on the third optical film 13 and the step of laminating the third adhesive layer 23 on the third optical film 13.

The step of bonding the polarizer 1 and the first optical film 11 via an adhesive and the step of bonding the polarizer 1 and the second optical film 12 via an adhesive are sequentially performed. You may go, or you may go at the same time.

When the first optical film 11 and the second optical film 12 are bonded to the polarizer 1 at the same time, it is preferable to provide a step of adjusting the water content of the polarizer before bonding. On the other hand, when the first optical film 11 and the second optical film 12 are sequentially laminated to the polarizer 1, before or after the first optical film is laminated to the polarizer, the moisture content of the polarizer is increased. It is preferable to provide a step of adjusting the rate. The water content of the polarizer may increase during transportation and storage of the produced polarizer. In order to adjust the water content in the above range, a step of adjusting the water content of the polarizer at the above timing, preferably a step of reducing the water content of the polarizer can be provided.

The method of adjusting the water content of the polarizer is not particularly limited, and examples thereof include a method of blowing dry air, a method of passing through a humidity control zone adjusted to low humidity, a method of passing through a hot air drying furnace, and an infrared heater. Examples thereof include a method of heating using a heating device, and a combination thereof.

From the viewpoint of preventing breakage of the polarizer, the step of adjusting the water content of the polarizer is preferably performed after the first optical film is attached to the polarizer. In this case, it is possible to take measures to prevent the polarizer from absorbing moisture in the atmosphere after the step of adjusting the moisture content of the polarizer is performed and before the second optical film is attached. preferable.

The method for preventing the polarizer from absorbing moisture is not particularly limited, and a method of temporarily attaching a peelable moisture-proof film to the exposed surface of the polarizer or a method of quickly attaching the film after attaching the first optical film Examples thereof include a method of winding the material in a roll shape to suppress invasion of moisture from the outside, and a method of further packing the rolled film with a moisture-proof film such as aluminum laminate. The moisture proof film has a moisture permeability of 100 g/m ² ·24 hr. It is preferably not more than 50 g/m ² ·24 hr. The following is more preferable.

Also, the drying step after washing in the production of the polarizer may also serve as the step of adjusting the water content of the polarizer. In this case, it is preferable to take measures to prevent the polarizer from absorbing moisture in the atmosphere immediately after the drying step (for example, within 3 minutes after the drying step, preferably within 1 minute). Examples of means for preventing the polarizer from absorbing moisture in the atmosphere include a method for preventing the polarizer from absorbing moisture, and a method of temporarily attaching a peelable moisture-proof film to the exposed surface of the polarizer is preferable. ..

The polarizing plate 101 may be manufactured by preparing long members, bonding each member by roll-to-roll, and then cutting it into a predetermined shape, or cutting each member into a predetermined shape. After doing, you may stick together.

(1) Method of measuring film thickness It was measured using MH-15M, a digital micrometer manufactured by Nikon Corporation.

(2) Method of measuring moisture permeability of optical film The moisture permeability was measured according to JIS Z 0208 (cup method) at a temperature of 40°C and a relative humidity of 90%.

(3) Method of measuring water vapor permeability of adhesive layer The water vapor permeability of the adhesive layer is measured under the conditions of a temperature of 40° C. and a relative humidity of 90% according to JIS K7129 using a water vapor permeability meter (L80 series manufactured by Lyssy). Was measured. The test method was the humidity sensor method.

[Polarizer]
A polyvinyl alcohol film with a thickness of 20 μm (average degree of polymerization: about 2400, saponification degree: 99.9 mol% or more) is uniaxially stretched about 5 times in the longitudinal direction by dry stretching, and further, while maintaining a tension state, with pure water at 60° C. After immersing for 1 minute, it was immersed for 60 seconds in an aqueous solution of 28° C. in which the weight ratio of iodine/potassium iodide/water was 0.05/5/100. Then, it was immersed for 300 seconds in an aqueous solution of 72° C. in which the weight ratio of potassium iodide/boric acid/water was 8.5/8.5/100. Subsequently, after washing with pure water at 3° C. for 20 seconds, water was removed with an air knife. A drying treatment was performed at a maximum temperature of 80° C. to obtain a polarizer having a thickness of 8 μm in which iodine was adsorbed and oriented on the polyvinyl alcohol film. Immediately after the drying treatment, a peelable moisture-proof film was temporarily attached to both sides of the polarizer and wound on a roll. The moisture-proof film has a moisture permeability of 30 g/m ² ·24 hr. Was used.

[First optical film]
First optical film A: A stretched cyclic olefin resin film having a hard coat layer on one surface was prepared. The thickness of the first optical film A was 30 μm. The water vapor transmission rate of the first optical film A is 20 g/m ² ·24 hr. Met.

First optical film B: A triacetyl cellulose film was prepared. The thickness of the first optical film B was 40 μm. The water vapor transmission rate of the first optical film B is 600 g/m ² ·24 hr. Met.

[Second optical film]
Second optical film A: A film in which a layer in which a polymerizable liquid crystal compound was cured was formed on a stretched cyclic olefin resin film was prepared. The stretched cyclic olefin resin film was a layer that gave a retardation of λ/4, and the layer in which the polymerizable liquid crystal compound was cured was a positive C layer. The thickness of the second optical film A was 21 μm. The water vapor permeability of the second optical film A is 20 g/m ² ·24 hr. Met.

Second optical film B: A triacetyl cellulose film was prepared. The thickness of the second optical film B was 20 μm. The water vapor permeability of the second optical film B is 1600 g/m ² ·24 hr. Met.

[Third optical film]
Third optical film A: cycloolefin resin film; ZF14-023. The thickness of the third optical film A was 23 μm. The moisture permeability of the third optical film A was 17 g/m ² ·24 hr.

[First adhesive layer]
First adhesive layer A: 97.0 parts by mass of n-butyl acrylate, 1.0 part by mass of acrylic acid, acrylic acid in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device and a nitrogen introducing tube. 0.5 parts by mass of 2-hydroxyethyl, 200 parts by mass of ethyl acetate, and 0.08 parts by mass of 2,2′-azobisisobutyronitrile were charged, and the air in the reaction vessel was replaced with nitrogen gas.
While stirring under a nitrogen atmosphere, the reaction solution was heated to 60° C., reacted for 6 hours, and then cooled to room temperature. The weight average molecular weight of the obtained acrylic acid ester polymer was 1,800,000.

100 parts by mass of (meth)acrylic acid ester polymer obtained in the above step (solid content conversion value; the same applies hereinafter), and trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, trade name " Coronate (registered trademark) L") 0.30 parts by mass, and as a silane coupling agent, 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM403") 0.30 parts by mass. Were mixed, sufficiently stirred, and diluted with ethyl acetate to obtain an adhesive composition.

The pressure-sensitive adhesive composition was applied onto the release-treated base film so that the thickness after drying was 25 μm. The pressure-sensitive adhesive composition was dried at 100° C. for 1 minute to obtain a first adhesive layer A. The water vapor transmission rate of the first adhesive layer A is 3600 g/m ² ·hr. Met.

[Second adhesive layer]
Second adhesive layer A: The same adhesive layer as the first adhesive layer A was used.

[Third adhesive layer]
Third adhesive layer A: The same adhesive layer as the first adhesive layer A was used.

[Example 1]
The film is unwound from a roll of a film in which a polarizer and a moisture-proof film are laminated, one moisture-proof film is peeled off, and the exposed surface of the polarizer is quickly and firstly bonded via an ultraviolet curable adhesive. The optical film A of was laminated. After peeling off the other moisture-proof film, the second optical film A was immediately attached to the exposed surface of the polarizer via an ultraviolet curable adhesive.
Further, the third optical film A was laminated on the first optical film A via the first adhesive layer A. The second adhesive layer A was laminated on the second optical film A. In addition, when laminating each layer, the laminating surface was subjected to corona treatment. In this way, a polarizing plate in which the third optical film A/first adhesive layer A/first optical film A/polarizer/second optical film A/second adhesive layer A are laminated in this order. Got The moisture content of the polarizer immediately before bonding the second optical film A was 0.5%.

[Comparative Example 1]
A polarizing plate was produced in the same manner as in Example 1 except that the third optical film A and the first adhesive layer A were not formed. This polarizing plate had a layer structure in which the first optical film A/polarizer/second optical film A/second adhesive layer A were laminated in this order.

[Comparative example 2]
Polarized light was obtained in the same manner as Comparative Example 1 except that the first optical film B was used instead of the first optical film A and the second optical film B was used instead of the second optical film A. A plate was made. This polarizing plate had a layer structure in which the first optical film B/polarizer/second optical film B/second adhesive layer A were laminated in this order.

[High temperature durability test]
The third adhesive layer A was formed on the surface of the polarizing plate opposite to the surface on the second adhesive layer A side. The polarizing plate was cut into a square having a size of 80 mm×80 mm. The polarizing plate was attached to a glass plate via the third adhesive layer A. A glass plate was also attached on the second adhesive layer. The glass plate was EAGLE XG (registered trademark) manufactured by Corning Incorporated, and the thickness thereof was 0.4 mm. The glass plate used was larger than the size of the polarizing plate. In this way, a laminated body for evaluation in which a pair of glass plates were laminated on both surfaces of the polarizing plate was produced.

The evaluation laminate was placed in an oven at a temperature of 105° C. for 48 hours. The laminate for evaluation was taken out of the oven, and it was visually confirmed whether the transmittance at the center of the surface was lowered. The above results are shown in Table 1.
◯: No decrease in transmittance was confirmed in the center of the plane.
Δ: A slight decrease in transmittance was confirmed at the center of the plane.
X: A decrease in transmittance was clearly confirmed in the central portion of the plane.

[High temperature and high humidity durability test]
A laminate for evaluation was prepared in the same manner as the high temperature durability test. After leaving the evaluation laminate for 12 hours in an environment of a temperature of 50° C., it was placed in an oven at a temperature of 85° C. and a relative humidity of 85% RH for 500 hours. The laminate for evaluation was taken out from the oven, and the luminosity correction polarization degree of the polarizing plate was measured.
The above results are shown in Table 1.

[Table 1]
┏━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┓
┃ ┃ Example 1 Comparative Example 1 Comparative Example 2 ┃
┣━━━━━━━━━━━━━╋━━━━━━━━━━━━━━━━┫
┃Water vapor permeability of the first optical film┃ ┃
┃ [g/m ²・24hr.] ┃ 20 20 600 ┃
┠─────────────╂───────────────┨
┃Water vapor permeability of the second optical film┃ ┃
┃ [g/m ²・24hr.] ┃ 20 20 1600 ┃
┠─────────────╂───────────────┨
┃ With or without third optical film ┃ Yes No No ┃
┣━━━━━━┯━━━━━━╋━━━━━━━━━━━━━━━┫
┃High temperature │105℃ ┃○ × ○ ┃
┃Endurance test │168 hours ┃ ┃
┠──────┼──────╂───────────────┨
┃ High temperature and high humidity │ 85℃ 85% RH ┃ 99% 99% <80% ┃
┃Durability test │500 hours ┃ ┃
┗━━━━━━┷━━━━━━┻━━━━━━━━━━━━━━━┛

The polarizing plates of the examples are less likely to reduce the transmittance of the in-plane central portion even when placed in a high temperature environment, and the polarization degree is reduced even when placed in a high temperature and high humidity environment. It was difficult.
On the other hand, when the polarizing plate of Comparative Example 1 was placed in a high temperature environment, the transmittance of the in-plane central portion was lowered. The polarizing plate of Comparative Example 2 showed a large decrease in the degree of polarization when placed in a high temperature and high humidity environment.

According to the present invention, the transmittance of the in-plane central portion is unlikely to decrease even when placed in a high temperature environment, and the polarization degree is less likely to decrease even when placed in a high temperature and high humidity environment. It is useful because a polarizing plate is provided.

1 Polarizer 11 1st Optical Film 12 2nd Optical Film 13 3rd Optical Film 21 1st Adhesive Layer 22 2nd Adhesive Layer 23 3rd Adhesive Layer 31 Front Plate 32 Display Element 101 Polarizing Plate 201 Display apparatus

Claims (5)

The polarizer, the first optical film laminated on one surface of the polarizer, the second optical film laminated on the other surface of the polarizer, and the polarizer side of the first optical film are opposite to each other. And a third optical film disposed on the side,
The first optical film and the third optical film are films arranged on the viewing side based on the polarizer,
The water vapor transmission rate of the first optical film is 100 g/m ² ·24 hr. Is less than
The water vapor permeability of the second optical film is 100 g/m ² ·24 hr. The following is a polarizing plate. Having a first adhesive layer between the first optical film and the third optical film,
The polarizing plate according to claim 1, wherein the first optical film and the third optical film are in contact with the first adhesive layer. The water vapor transmission rate of the first adhesive layer is 500 g/m ² ·24 hr. The polarizing plate according to claim 1 or 2, which is the above. A second adhesive layer laminated on the surface of the second optical film opposite to the polarizer side;
The polarizing plate according to any one of claims 1 to 3, further comprising a third adhesive layer laminated on a surface of the third optical film opposite to the polarizer side. A display device in which the polarizing plate according to claim 4 is laminated on a front plate via a third adhesive layer and laminated on a display element via a second adhesive layer.

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