JP6893407B2 - Polarizing plate and its manufacturing method - Google Patents

Description

The present invention relates to a polarizing plate and a method for producing the same. The present invention also relates to an image display device including the polarizing plate.

Various image display devices such as liquid crystal display devices and organic EL display devices are incorporated in various devices such as mobile devices such as mobile phones, personal computers, and large televisions. In mobile devices such as mobile phones, a front plate such as a cover glass or a cover glass with a touch sensor module (hereinafter referred to as a touch panel) is arranged on the surface on the visual side, and UV curing is performed between the front plate and the polarizing plate. A cured product layer of a sex resin is often arranged. By using the ultraviolet curable resin, it is possible to reduce the loss of light due to reflection between the polarizing plate and the front plate. As such an image display device, for example, Patent Document 1 discloses a liquid crystal display device in which an ultraviolet curable resin is interposed between a polarizing plate and a front plate.

Japanese Unexamined Patent Publication No. 2012-185432

In a liquid crystal display device as disclosed in Patent Document 1, in order to cure a liquid ultraviolet curable resin in a step of arranging a cured product layer of the ultraviolet curable resin between a front plate and a polarizing plate. Normally, ultraviolet rays are irradiated from the front plate side. At this time, it is preferable to irradiate a sufficient amount of ultraviolet rays from the viewpoint of easiness of curing.

In the present invention, not only the layer is cured by the ultraviolet rays irradiated from the side where the layer of the ultraviolet curable composition is formed, but also the ultraviolet rays reflected by the reflective layer are also cured, so that the adhesion to the front plate is obtained. It is an object of the present invention to provide a polarizing plate which is excellent in the above and can suppress peeling and floating from the front plate when used by being bonded to the front plate.

The present invention provides the following preferred embodiments [1] to [10].
[1] A polarizing plate including a polarizing element and an ultraviolet reflecting layer, and having a cured product layer composed of a cured product of an ultraviolet curable composition on at least one surface of the ultraviolet reflecting layer.
[2] A cured product layer composed of a cured product of the ultraviolet curable composition is provided on a surface of the ultraviolet reflecting layer opposite to the polarizer side, and the ultraviolet reflecting layer is an adhesive layer or an adhesive. The polarizing plate according to the above [1], which is laminated on a polarizing element via a layer.
[3] The ultraviolet reflective layer is laminated on a polarizer via an adhesive layer, and the adhesive layer is selected from the group consisting of an ultraviolet curable adhesive, an electron beam curable adhesive, and a water-based adhesive. The polarizing plate according to the above [2], which is a cured product layer of an adhesive.
[4] A polarizing plate with a front plate provided with the polarizing plate and the front plate according to the above [2] or [3], and the front plate is laminated on a surface of the cured product layer opposite to the polarizer side. ..
[5] An image display device including the polarizing plate according to any one of the above [1] to [3] or the polarizing plate with a front plate according to the above [4].
[6] The method for producing a polarizing plate according to any one of [1] to [4] above.
Forming a layer of UV curable composition on one surface of the UV reflective layer, and
A method comprising irradiating ultraviolet rays from the side of the ultraviolet reflective layer on which the layer of the ultraviolet curable composition is formed to cure the ultraviolet curable composition.
[7] The method for producing a polarizing plate according to the above [1].
A layer of an ultraviolet curable composition is formed on one surface of a polarizer, and an ultraviolet reflective layer is bonded onto the layer.
A method comprising irradiating ultraviolet rays from the polarizer side to cure the ultraviolet curable composition.
[8] A polarizing plate having an ultraviolet reflecting layer on one side of a polarizing element.
[9] The polarizing plate according to the above [8], wherein the ultraviolet reflective layer is laminated on a polarizer via an adhesive layer or an adhesive layer.
[10] The above-mentioned [8] or [9] used for forming a cured product layer composed of a cured product of an ultraviolet curable composition on a surface of the ultraviolet reflecting layer opposite to the polarizer side. Polarizing plate.

According to the present invention, it is possible to provide a polarizing plate having excellent adhesion to a front plate and capable of suppressing peeling or floating from the front plate when used by being bonded to the front plate. Further, it is possible to provide an image display device including the polarizing plate.

It is the schematic which shows an example of the layer structure of the polarizing plate of this invention. It is the schematic which shows an example of the layer structure of the polarizing plate of this invention. It is the schematic which shows an example of the layer structure of the polarizing plate of this invention. It is the schematic which shows an example of the layer structure of the polarizing plate with a front plate of this invention. It is the schematic which shows an example of the layer structure of the image display device (liquid crystal display device) of this invention.

Hereinafter, embodiments of the present invention will be described in detail. The scope of the present invention is not limited to the embodiments described here, and various modifications can be made without impairing the gist of the present invention.
The polarizing plate of the present invention includes a polarizer and an ultraviolet reflecting layer, and in one embodiment, a cured product layer composed of a cured product of an ultraviolet curable composition on at least one surface of the ultraviolet reflecting layer (hereinafter, "" It also has an "ultraviolet curable layer").

For example, when the configuration in one preferred embodiment of the present invention is described with reference to FIGS. 1 to 3, the polarizing plate (10) shown in FIG. 1 is an ultraviolet reflecting layer laminated on one side of the polarizer (1). It includes (2) and an ultraviolet cured product layer (3) laminated on a surface of the ultraviolet reflecting layer (2) opposite to the polarizer (1) side. In the polarizing plate (10) according to the embodiment of the present invention shown in FIG. 1, the ultraviolet reflecting layer (2) is a polarizing element (1) such as an adhesive layer or an adhesive layer and an ultraviolet reflecting layer (2). It may be laminated on the polarizer (1) via the layer (4) having a function of adhering the and. Further, the polarizing plate (10) shown in FIG. 2 includes an ultraviolet reflecting layer (2) laminated on one side of the polarizing element (1) via an ultraviolet cured product layer (3). Further, the polarizing plate (10) shown in FIG. 3 includes an ultraviolet reflecting layer (2) laminated on one side of a polarizing element (1) via an ultraviolet cured product layer (3), and further, the ultraviolet reflecting layer (2). ) Is provided with an ultraviolet cured product layer (3) laminated on the surface opposite to the polarizer (1) side. In the polarizing plate (10) of the present invention, for example, as shown in FIG. 4, the ultraviolet cured product layer (3) laminated on the surface of the ultraviolet reflecting layer (2) opposite to the polarizer (1) side is formed. The polarizing plate with a front plate (20) of the present invention is obtained by laminating the polarizing plate (5) with the front plate via the front plate (5).

In a conventional polarizing plate, when laminated on a front plate or the like via a cured product layer obtained by curing an ultraviolet curable composition, among the irradiated ultraviolet rays, the ultraviolet rays transmitted through the layer of the ultraviolet curable composition are emitted. It could not be used for curing. On the other hand, the polarizing plate of the present invention contains a UV-reflecting layer, so that when the layer of the UV-curable composition is provided adjacent to or close to the UV-reflecting layer, the layer of the UV-curable composition In addition to the ultraviolet rays that are directly used for curing by being irradiated to, the ultraviolet rays reflected by the ultraviolet reflective layer can also be used for curing, so that the curing of the ultraviolet curable composition can be promoted. It is possible to improve the adhesion with the layer laminated via the ultraviolet curable material layer such as a face plate. Further, since the layer of the ultraviolet curable composition can be efficiently cured, a polarizing plate having high adhesion to the front plate or the like can be obtained even with a small amount of ultraviolet irradiation or short-time ultraviolet irradiation, which is energy efficient. It is also advantageous in terms of productivity and productivity. Therefore, in the polarizing plate of the present invention having an ultraviolet reflecting layer on one side of the polarizing element, a cured product layer composed of a cured product of the ultraviolet curable composition is provided on the surface of the ultraviolet reflecting layer opposite to the polarizer side. It is a polarizing plate for forming a cured product layer, which can be suitably used for forming.

Hereinafter, each constituent member of the polarizing plate of the present invention will be described in detail.

<Polarizer>
The polarizer is an optical film having a property of absorbing linearly polarized light having a vibrating surface parallel to the optical axis and transmitting linearly polarized light having a vibrating surface orthogonal to the optical axis (parallel to the transmission axis). For example, a film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film can be used. Examples of the dichroic dye include iodine and a dichroic organic dye.

The thickness of the polarizer is usually 2 μm or more and 30 μm or less, preferably 25 μm or less, more preferably 15 μm or less, still more preferably 10 μm or less, and particularly preferably 7 μm or less. When a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented is applied as a polarizer, the polyvinyl alcohol-based resin alone may be stretched, or a solution of the polyvinyl alcohol-based resin may be used as a base material. May be applied and dried, and then stretched together with the base material to remove the base material. When stretched together with a base material, for example, a thin-film polarizer having a thickness of 7 μm or less can be easily produced. Examples of the base material include polyethylene terephthalate film, polycarbonate film, triacetyl cellulose film, norbornene film, polyester film, polystyrene film and the like.

As the polyvinyl alcohol-based resin constituting the polyvinyl alcohol-based resin film, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable therewith. Other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamides with ammonium groups and the like.

The saponification degree of the polyvinyl alcohol-based resin is usually 80 mol% or more, preferably 90 to 100 mol%, and more preferably 94 to 100 mol%. When the saponification degree is at least the above lower limit, the water resistance and moisture heat resistance of the obtained polarizing plate are good, and when the saponification degree is at least the above upper limit, the dyeing speed is high and efficient production can be performed. A polarizer having sufficient polarization performance can be obtained.

The polyvinyl alcohol-based resin may be a partially modified modified polyvinyl alcohol, for example, olefin modification with ethylene, propylene or the like; unsaturated carboxylic acid modification with acrylic acid, methacrylic acid, crotonic acid or the like; unsaturated. Alkyl esters of carboxylic acids, those modified with acrylamide, etc. may be used. The modification rate of the polyvinyl alcohol-based resin is preferably less than 30 mol%, more preferably less than 10%. When the modification rate is in the above range, the dichroic dye is easily adsorbed, and a polarizer having sufficient polarization performance can be obtained.

The average degree of polymerization of the polyvinyl alcohol-based resin is preferably about 100 to 10000, more preferably 1500 to 8000, and further preferably 2000 to 5000. When the average degree of polymerization is at least the above lower limit, sufficient polarization performance can be obtained, and when the average degree of polymerization is at least the above upper limit, the solubility in a solvent is good and a polyvinyl alcohol-based resin film can be easily formed. can do.

As the polyvinyl alcohol-based resin, an appropriate commercially available product can be used. Suitable commercially available products include, for example, "PVA124" and "PVA117" (both have a degree of saponification: 98 to 99 mol%) and "PVA624" (a degree of saponification: 95) manufactured by Kuraray Co., Ltd. ~ 96 mol%), "PVA617" (concentration: 94.5-95.5 mol%); "N-300" and "NH-18" (both depreciation) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. : 98-99 mol%), "AH-22" (kenning degree: 97.5-98.5 mol%), "AH-26" (kenning degree: 97-98.8 mol%) ,; Japan "JC-33" (kenning degree: 99 mol% or more), "JF-17", "JF-17L" and "JF-20" manufactured by Vinegar Poval Co., Ltd. (kenning degree: 98 ~ 99 mol%), "JM-26" (kenning degree: 95.5-97.5 mol%), "JM-33" (kenning degree: 93.5-95.5 mol%) and "JP- 45 ”(degree of saponification: 86.5 to 89.5 mol%) and the like can be mentioned.

The polarizer is usually a step of uniaxially stretching such 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, and a dichroic dye. It is produced through a step of treating the adsorbed polyvinyl alcohol-based resin film with an aqueous boric acid solution and a step of washing with water after the treatment with the aqueous boric acid solution. By dyeing the polyvinyl alcohol-based resin film with the dichroic dye, the dichroic dye is contained in the polyvinyl alcohol-based resin film. When the polarizer is produced by such a production method, the polarizer is a stretched polyvinyl alcohol-based resin film containing a dichroic dye.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be carried out before dyeing the dichroic dye, at the same time as dyeing, or after dyeing. If the uniaxial stretching is performed after staining, the uniaxial stretching may be performed before the boric acid treatment or during the boric acid treatment. It is also possible to perform uniaxial stretching in these a plurality of steps. In uniaxial stretching, rolls having different peripheral speeds may be uniaxially stretched, or thermal rolls may be used to uniaxially stretch the rolls. Further, the uniaxial stretching may be a dry stretching performed in the atmosphere, or a wet stretching performed in a state where the polyvinyl alcohol-based resin film is swollen using a solvent. The draw ratio is preferably 8 times or less, more preferably 7.5 times or less, still more preferably 7 times or less, from the viewpoint of suppressing deformation of the polarizer. Further, the draw ratio is usually 3 times or more from the viewpoint of expressing the function as a polarizer. By setting the draw ratio within the above range, deformation of the polarizer over time can be suppressed.

Examples of the method of dyeing the polyvinyl alcohol-based resin film with the dichroic dye include a method of immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, for example, iodine or a dichroic organic dye is used. Bicolor organic dyes include Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B. , Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Direct Sky Blue , Direct First Orange S, First Black and the like. As the dichroic dye, only one kind may be used alone, or two or more kinds may be used in combination. The polyvinyl alcohol-based resin film is preferably immersed in water before the dyeing treatment.

When iodine is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide for dyeing is usually adopted. The content of iodine in this aqueous solution is usually 0.01 to 1 part by mass per 100 parts by mass of water, and the content of potassium iodide is usually 0.5 to 20 parts by mass per 100 parts by mass of water. .. When iodine is used as the dichroic dye, the temperature of the aqueous solution used for dyeing is usually 20 to 40 ° C., and the immersion time (dyeing time) in this aqueous solution is usually 20 to 1800 seconds.
Before immersing the polyvinyl alcohol-based resin film in the aqueous solution containing iodine and potassium iodide, the film may be immersed in water in order to swell and facilitate dyeing. The temperature of the dipping treatment is usually 20 to 80 ° C., preferably 30 to 60 ° C., and the dipping time (staining time) is usually about 20 to 1800 seconds.

When a dichroic dye is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye and dyeing is usually adopted. The content of the dichroic dye in this aqueous solution is usually 1 × 10 ^-4 to 10 parts by mass, preferably 1 × 10 ^-3 to 1 part by mass, and more preferably 1 × 10 ^{− per 100 parts by mass of water. 3} to 1 × ^10-2 parts by mass. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. When a dichroic dye is used as the dichroic dye, the temperature of the dye aqueous solution used for dyeing is usually 20 to 80 ° C., and the immersion time (dyeing time) in this aqueous solution is usually 10 to 1800 seconds. is there.

The boric acid treatment after dyeing with a dichroic dye can be performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous boric acid solution. The amount of boric acid in the boric acid aqueous solution is usually 2 to 15 parts by mass, preferably 5 to 12 parts by mass per 100 parts by mass of water. When iodine is used as the dichroic pigment, this boric acid aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid aqueous solution is usually 0.1 to 15 parts by mass, preferably 5 to 12 parts by mass per 100 parts by mass of water. The immersion time in the boric acid aqueous solution is usually 60 to 1200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., and more preferably 60 to 80 ° C.

The polyvinyl alcohol-based resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing the boric acid-treated polyvinyl alcohol-based resin film in water. The temperature of water in the washing treatment is usually 5 to 40 ° C., and the immersion time is usually 1 to 120 seconds. After washing with water, a drying treatment is performed to obtain a polarizer. The drying process can be performed using a hot air dryer or a far-infrared heater. The temperature of the drying treatment is usually 30 to 100 ° C., preferably 40 to 95 ° C., more preferably 50 to 90 ° C. The drying treatment time is usually 40 to 600 seconds, preferably 50 to 600 seconds, and more preferably 60 to 600 seconds.

As described above, a polarizer can be obtained by subjecting the polyvinyl alcohol-based resin film to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment.

<UV reflective layer>
In the polarizing plate of the present invention, the ultraviolet reflecting layer may have any form as long as it can reflect ultraviolet rays (light having a wavelength of 200 nm to 400 nm). For example, it may be a single-layer film or a multi-layered film. Further, the transparent film may be coated with an ultraviolet reflective layer. In the polarizing plate of the present invention, as the ultraviolet reflective layer, for example, a display film described in JP-A-2015-194566, a multilayer optical film described in JP-A-2016-26323, and the like can be used. it can. The ultraviolet reflective layer usually has a visible light transmittance of 80% or more, preferably 85% or more, and is preferably transparent over the entire range of visible light (460 nm to 720 nm). The visible light transmittance of the ultraviolet reflective layer can be measured by the method described in Examples described later.

In the present invention, the "ultraviolet reflective layer" measures the reflectance of the front surface (0 ° direction of incident light) with respect to the thickness direction of the target layer every 2 nm between wavelengths of 280 to 380 nm. It means a layer in which the average value of the obtained reflectance (ultraviolet average reflectance) is 10% or more. When the ultraviolet average reflectance of the ultraviolet reflective layer is 15% or more, when the layer of the ultraviolet curable composition is irradiated with ultraviolet rays, the reflected light by the ultraviolet reflecting layer can be utilized in addition to the irradiation light, so that the ultraviolet curable Curing of the composition can be further accelerated. In the polarizing plate of the present invention, the ultraviolet average reflectance of the ultraviolet reflective layer is more preferably 20% or more, further preferably 25% or more. The ideal ultraviolet average reflectance is 100%, but it is usually 90% or less, and may be, for example, 70% or less.

The ultraviolet transmittance of the ultraviolet reflective layer is preferably 30% or less, more preferably 20% or less, and further preferably 15% or less. When the ultraviolet transmittance of the ultraviolet reflecting layer is not more than the above upper limit value, the amount of ultraviolet rays transmitted through the ultraviolet reflecting layer is reduced, and the irradiated ultraviolet rays can be used more effectively, so that the ultraviolet curable composition can be cured. It can be promoted more. In addition, deterioration of the liquid crystal cell or the like due to ultraviolet rays transmitted through the ultraviolet reflective layer during ultraviolet irradiation can be suppressed. The lower limit of the ultraviolet transmittance of the ultraviolet reflective layer is not particularly limited, and is ideally 0%, but is usually 0.5% or more, and may be, for example, 1% or more.
In the present invention, the ultraviolet transmittance means an average value (ultraviolet average transmittance) of the transmittance measured by irradiating the ultraviolet reflective layer with a wavelength of 280 to 380 nm every 2 nm.

In the polarizing plate of the present invention, the ultraviolet reflective layer may absorb a small amount of ultraviolet rays or may transmit a small amount of ultraviolet rays as long as it can maintain an average ultraviolet reflectance of 10% or more. In addition, an ultraviolet absorber may be contained if necessary. Since the ultraviolet reflecting layer contains an ultraviolet absorber, the amount of ultraviolet rays transmitted through the ultraviolet reflecting layer can be reduced, and deterioration of the liquid crystal cell or the like due to the ultraviolet rays transmitted through the ultraviolet reflecting layer during ultraviolet irradiation can be suppressed. As a method for containing an ultraviolet absorber in the ultraviolet reflecting layer, the description in paragraph [0028] of JP2015-194566A can be referred to.
In the polarizing plate of the present invention, the layers other than the ultraviolet reflective layer may contain an ultraviolet absorber, only one layer may contain an ultraviolet absorber, and the ultraviolet reflecting layer and the ultraviolet reflecting layer. A plurality of layers other than the above may contain an ultraviolet absorber.

<Cured product layer of UV curable composition>
In one embodiment, the polarizing plate of the present invention comprises a cured product layer (ultraviolet curable product layer) composed of a cured product of an ultraviolet curable composition. In one embodiment of the present invention, the UV curable layer is provided on at least one surface of the UV reflective layer, and the UV curable layer may be provided on both sides of the UV reflective layer.
In one preferred embodiment of the present invention, the UV curable layer is provided, for example, on the outermost surface of the polarizing plate, fills the air gap between the front plate and the polarizing plate, and adheres the front plate and the polarizing plate. Has a function. By filling the air gap with an ultraviolet curable composition, impact resistance can be enhanced and light loss due to reflection can be reduced. Further, the ultraviolet curable material layer can also function as an adhesive layer constituting a polarizing plate. For example, by providing an ultraviolet curable material layer as an adhesive layer for adhering a polarizing element to an ultraviolet reflective layer or the like, adhesion is achieved. Can be a high adhesive layer.

When an ultraviolet cured product layer is provided on the outermost layer of the polarizing plate to bond the polarizing plate and the front plate, the thickness of the ultraviolet cured product layer is usually 30 to 200 μm, preferably 50 to 200 μm, and more. It is preferably 80 to 150 μm. When the thickness of the ultraviolet cured product layer is within the above range, the adhesion between the polarizing plate and the front plate is good. When an ultraviolet curable layer is provided as an adhesive layer for adhering a polarizer to an ultraviolet reflective layer or the like, the thickness of the ultraviolet curable layer is preferably 0.01 to 5 μm, preferably 0.1 to 4 μm. Is more preferable.

The UV curable layer is preferably optically transparent. Here, optically transparent means having a transmittance of 85% or more over 460 to 720 nm. In the polarizing plate of the present invention, the transmittance of the ultraviolet cured product layer is preferably 90% or more, more preferably 92% or more. The transmittance of the UV-cured product layer is ideally 100%, but is usually 98% or less.

In the present invention, the ultraviolet average reflectance of the ultraviolet cured product layer is usually 50% or less, preferably 30% or less, more preferably 20% or less, and particularly preferably less than 10%. .. The lower limit of the average UV reflectance of the UV-cured product layer is not particularly limited, but is ideally 0%, usually 0.1% or more. The ultraviolet average reflectance can be measured by the same method as described above as the method for measuring the ultraviolet average reflectance in the ultraviolet reflective layer.

Further, when the ultraviolet cured product layer is arranged as an adhesive layer between the front plate and the polarizing plate, the refractive index of the ultraviolet cured product layer is preferably close to the refractive index of the front plate and / or the ultraviolet reflecting layer. It is preferably .4 to 1.7. Since the refractive index of the UV-cured product layer is close to the refractive index of the front plate and / or the UV-reflecting layer, reflection and light scattering at the interface between the front plate and / or the polarizing plate are reduced, and visibility is improved. be able to.

The ultraviolet curable layer can be formed by irradiating the layer of the ultraviolet curable composition with ultraviolet rays and curing the layer. The layer of the UV curable composition may be adjacent to the UV reflective layer, and the UV curable composition as long as the UV reflected by the UV reflective layer can be used to cure the UV curable composition. Another layer may be interposed between the layer and the UV-reflecting layer (that is, in the obtained polarizing plate, another layer may be interposed between the UV-cured product layer and the UV-reflecting layer). ..

<UV curable composition>
The UV curable composition constituting the UV curable layer in the polarizing plate of the present invention is usually a composition that is liquid at room temperature and contains a polymerizable compound. Examples of the polymerizable compound include a cationically polymerizable compound and a radically polymerizable compound, and a radically polymerizable compound is preferable from the viewpoint of improving the adhesion between the front plate and the UV-cured product layer. Examples of the cationically polymerizable compound include a compound having at least one oxetane ring (4-membered ring ether) in the molecule (hereinafter referred to as an oxetane compound) and at least one oxylan ring (3-membered ring ether) in the molecule. Examples thereof include compounds having (hereinafter referred to as epoxy compounds). As the radically polymerizable compound, a compound having at least one (meth) acryloyloxy group in the molecule (hereinafter, referred to as a (meth) acrylic compound) is preferable. In the present specification, the (meth) acryloyloxy group means a methacryloyloxy group or an acryloyloxy group, and the same applies to other terms with (meth).

Examples of the (meth) acrylic compound include a (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule and a (meth) acrylate having at least two (meth) acryloyloxy groups in the molecule. Examples include oligomers. Each of these may be used alone, or two or more thereof may be used in combination. When two or more kinds are used in combination, it may be a combination of two or more kinds of (meth) acrylate monomers or a combination of two or more kinds of (meth) acrylate oligomers. Of course, one or more (meth) acrylate monomers and one or more (meth) acrylate oligomers may be used in combination.

Examples of the (meth) acrylate monomer include a monofunctional (meth) acrylate monomer having one (meth) acryloyloxy group in the molecule and a bifunctional (meth) acrylate monomer having two (meth) acryloyloxy groups in the molecule. Examples thereof include (meth) acrylate monomers and polyfunctional (meth) acrylate monomers having three or more (meth) acryloyloxy groups in the molecule.

Examples of the monofunctional (meth) acrylate monomer include tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. 4-Hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) Acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, cyclohexyl (meth) Meta) acrylate, 1,4-cyclohexanedimethanol monoacrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, phenoxyethyl (meth) acrylate, Dicyclopentenyloxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, ethylcarbitol (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate And so on.

As the monofunctional (meth) acrylate monomer, a (meth) acrylate monomer containing a carboxyl group may be used. Examples of the carboxyl group-containing monofunctional (meth) acrylate monomer include 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, carboxyethyl (meth) acrylate, and 2-(. Examples thereof include meta) acryloyloxyethyl succinic acid, N- (meth) acryloyloxy-N', N'-dicarboxymethyl-p-phenylenediamine, and 4- (meth) acryloyloxyethyl trimellitic acid.

Examples of the bifunctional (meth) acrylate monomer include ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, and 1,6-hexanediol. Di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropandi (meth) acrylate, pentaerythritol di (meth) acrylate, ditrimethylol propanedi (meth) ) Acrylate, Diethylene glycol di (meth) acrylate, Triethylene glycol di (meth) acrylate, Dipropylene glycol di (meth) acrylate, Tripropylene glycol di (meth) acrylate, Polyethylene glycol di (meth) acrylate, Polypropylene glycol di (meth) ) Acrylate, Polytetramethylene glycol di (meth) acrylate, Silicone di (meth) acrylate, Di (meth) acrylate of neopentyl glycol ester of hydroxypivalate, 2,2-bis [4- (meth) acryloyloxyethoxyethoxyphenyl ] Propane, 2,2-bis [4- (meth) acryloyloxyethoxyethoxycyclohexyl] propane, hydrogenated dicyclopentadienyldi (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, 1,3- Dioxane-2,5-diyldi (meth) acrylate [also known as dioxane glycol di (meth) acrylate], an acetal compound of hydroxypivalaldehyde and trimethylolpropane [chemical name: 2- (2-hydroxy-1,1-) Di (meth) acrylate of [dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane], tris (hydroxyethyl) isocyanurate di (meth) acrylate and the like can be mentioned.

Examples of the trifunctional or higher functional polyfunctional (meth) acrylate monomer include glycerin tri (meth) acrylate, trimethylol propanetri (meth) acrylate, ditrimethylol propanetri (meth) acrylate, and ditrimethylol propanetetra (meth) acrylate. Trifunctional or higher functional fats such as pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate. Examples include poly (meth) acrylates of group polyols. In addition, poly (meth) acrylate of trifunctional or higher functional halogen-substituted polyol, tri (meth) acrylate of alkylene oxide adduct of glycerin, tri (meth) acrylate of alkylene oxide adduct of trimethylolpropane, 1,1,1- Tris [(meth) acryloyloxyethoxyethoxy] propane, tris (hydroxyethyl) isocyanurate tri (meth) acrylates and the like can be mentioned.

Examples of the (meth) acrylate oligomer include urethane (meth) acrylate oligomer, polyester (meth) acrylate oligomer, and epoxy (meth) acrylate oligomer.

A urethane (meth) acrylate oligomer is a compound having a urethane bond (-NHCOO-) and at least two (meth) acryloyloxy groups in the molecule. Specifically, a product of a urethanization reaction between a hydroxyl group-containing (meth) acrylate monomer having at least one (meth) acryloyloxy group and at least one hydroxyl group in the molecule and polyisocyanate, or a polyol and polyisocyanate. The product of a urethanization reaction between a terminal isocyanato group-containing urethane compound obtained by reacting with and a (meth) acrylate monomer having at least one (meth) acryloyloxy group and at least one hydroxyl group in the molecule. And so on.

Examples of the hydroxyl group-containing (meth) acrylate monomer used in the urethanization reaction include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 2-hydroxy-3. -Phenoxypropyl (meth) acrylate, glycerindi (meth) acrylate, trimerol propandi (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate and the like.

Examples of the polyisocyanate to be subjected to the urethanization reaction with the hydroxyl group-containing (meth) acrylate monomer include hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and the above diisocyanates. Diisocyanates obtained by hydrogenating aromatic isocyanates (eg, hydrogenated tolylene diisocyanates, hydrogenated xylylene diisocyanates, etc.), di- or tri-isocyanates such as triphenylmethane triisocyanates, dibenzylbenzene triisocyanates, and Examples thereof include polyisocyanate obtained by increasing the amount of the above diisocyanate.

Examples of the polyols used to obtain a terminal isocyanato group-containing urethane compound by reaction with polyisocyanate include aromatic, aliphatic and alicyclic polyols, as well as polyester polyols and polyether polyols. .. Examples of the aromatic polyol include 1,4-benzenedimethanol, 1,3-benzenedimethanol, 1,2-benzenedimethanol, 4,4'-naphthalenedimethanol, and 3,4'-naphthalenedimethanol. And so on. Aliphatic and alicyclic polyols include, for example, 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylolethane, and trimethylolpropane. , Ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptan, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, hydrogenated bisphenol A and the like.

The polyester polyol is obtained by a dehydration condensation reaction between the above-mentioned polyols and a polybasic carboxylic acid or an anhydride thereof. Examples of the polybasic carboxylic acid or its anhydride include succinic acid, succinic anhydride, adipic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, trimellitic acid, trimellitic anhydride, pyromellitic acid, and anhydrous. There are pyromellitic acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, hexahydrophthalic acid, hexahydrophthalic anhydride and the like.

Examples of the polyether polyol include polyalkylene glycol, polyoxyalkylene-modified polyol obtained by reacting the above-mentioned polyols or dihydroxybenzenes with alkylene oxide, and the like.

A polyester (meth) acrylate oligomer is a compound having at least two ester bonds and at least two (meth) acryloyloxy groups in the molecule. Specifically, it can be obtained by a dehydration condensation reaction of (meth) acrylic acid, a polybasic carboxylic acid or an anhydride thereof, and a polyol. The polybasic carboxylic acid or its anhydride used in the dehydration condensation reaction includes succinic acid, succinic anhydride, adipic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, trimellitic acid, and trimellitic anhydride. Acids, pyromellitic acid, phthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid and the like can be mentioned. The polyols used in the dehydration condensation reaction include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylolethane, and trimethylolpropane. , Ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptan, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, hydrogenated bisphenol A and the like.

The epoxy (meth) acrylate oligomer has at least two (meth) acryloyloxy groups in the molecule and can be obtained by an addition reaction between polyglycidyl ether and (meth) acrylic acid. Examples of the polyglycidyl ether used in the addition reaction include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and bisphenol A diglycidyl ether.

In the polarizing plate of the present invention, the ultraviolet curable composition constituting the ultraviolet curable layer preferably contains a total of 20 to 90 parts by mass of the polymerizable compound with respect to 100 parts by mass of the ultraviolet curable composition, and 30 to 30 parts by mass. It preferably contains 80 parts by mass. When the content of the polymerizable compound is in the above range, the film thickness of the UV-cured product layer can be easily adjusted. In particular, from the viewpoint of adhesion between the front plate and the UV curable layer, the UV curable composition may contain a total of 20 to 80 parts by mass of the radically polymerizable compound with respect to 100 parts by mass of the UV curable composition. It is preferably contained in an amount of 30 to 70 parts by mass, more preferably.

The UV curable composition preferably contains a polymerization initiator. When a radically polymerizable compound is contained as the polymerizable compound, it is preferable to contain a radical polymerization initiator, and when a cationically polymerizable compound is contained as the polymerizable compound, it is preferable to include a cationic polymerization initiator. The cationic polymerization initiator may be any one that generates a cationic species or Lewis acid by irradiation with active energy rays and initiates a polymerization reaction of a cationically polymerizable compound typified by an epoxy compound. As the radical polymerization initiator, any known radical polymerization initiator may be used as long as it can initiate the polymerization of a radically polymerizable compound such as a (meth) acrylic compound by irradiation with active energy rays. Further, the polymerization initiator preferably has an absorption maximum in the wavelength region of 280 to 380 nm. When there is an absorption maximum in this wavelength range, the ultraviolet rays reflected by the ultraviolet reflecting layer can be effectively utilized.

Examples of the radical polymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethylketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, and 2-methyl-1- [4. Acetphenone-based initiators such as- (methylthio) phenyl-2-morpholinopropane-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone, 4-chlorobenzophenone and 4,4'. -Benzophenone-based initiators such as diaminobenzophenone; benzoin ether-based initiators such as benzoinpropyl ether and benzoin ethyl ether; thioxanthone-based initiators such as 4-isopropylthioxanthone; and others, xanthone, fluorenone, phenylquinone, benzaldehyde, Anthraquinone and the like can be mentioned.

Commercially available products of the radical polymerization initiator can be easily obtained. For example, under the trade names of BASF, "Irgacure (registered trademark) 184", "Irgacure (registered trademark) 907", and "Darocure (registered)" "Trademark) 1173", "Lucirin (registered trademark) TPO" and the like can be used.

The content of the radical polymerization initiator in the ultraviolet curable composition is usually 0.5 to 20 parts by mass, preferably 1 part by mass, based on 100 parts by mass of the total amount of the radical polymerizable compound such as the (meth) acrylic compound. ~ 6 parts by mass. When the content of the radical polymerization initiator is in the above range, the ultraviolet curable composition can be sufficiently cured, and excellent adhesion between the ultraviolet curable layer and the front plate or the polarizer can be ensured. ..

The content of the cationic polymerization initiator in the ultraviolet curable composition is usually 0.5 to 20 parts by mass, preferably 1 to 6 parts by mass, based on 100 parts by mass of the total amount of the cationically polymerizable compound such as an epoxy compound. Is. When the content of the cationic polymerization initiator is in the above range, the ultraviolet curable composition can be sufficiently cured, and excellent adhesion between the ultraviolet curable layer and the front plate or the polarizer can be ensured. ..

The UV curable composition may contain a plasticizer, a photosensitizer, a leveling agent, an antioxidant, a stabilizer, a flame retardant, a viscosity modifier, a defoaming agent, an antistatic agent and the like.

In the polarizing plate of the present invention, the ultraviolet reflective layer may be laminated on the polarizer via an adhesive layer or an adhesive layer.

<Adhesive layer and adhesive layer>
The adhesives constituting the adhesive layer include ultraviolet curable adhesives, active energy ray-curable adhesives other than ultraviolet curable (for example, electron beam curable adhesives), water-based adhesives, organic solvent-based adhesives, and the like. Examples thereof include solvent-free adhesives. Among them, an adhesive selected from the group consisting of an ultraviolet curable adhesive, an electron beam curable adhesive, and a water-based adhesive is preferable because the adhesive layer to be formed can be thinned.

Examples of the ultraviolet curable adhesive include the above-mentioned ultraviolet curable composition, and when the ultraviolet reflective layer and the polarizer are bonded by the ultraviolet curable adhesive, the ultraviolet curable adhesive is the ultraviolet reflective layer. It may be the same as the UV curable composition constituting the UV curable layer laminated on one surface, or may be a different UV curable composition. The adhesive layer can also function as a protective film by forming an adhesive layer for adhering the ultraviolet reflective layer and the polarizer with the ultraviolet curable composition and controlling the thickness thereof.

Examples of the electron beam-curable adhesive include the adhesive described in JP2013-174922A.

Examples of the water-based adhesive include an adhesive containing a polyvinyl alcohol-based resin or a urethane resin as a main component. As an example of the water-based adhesive, there is a polyvinyl alcohol-based resin as an example of an adhesive component that is soluble in water. Further, to give an example of an adhesive component that can be dispersed in water, there is a urethane-based resin having a hydrophilic group. Water-based adhesives can be prepared by mixing such adhesive components with water, along with additional additives to be added as needed. Examples of commercially available polyvinyl alcohol-based resins that can be water-based adhesives include "KL-318" (trade name), which is a carboxyl group-modified polyvinyl alcohol sold by Kuraray Co., Ltd.

The water-based adhesive may contain a cross-linking agent, if necessary. Examples of cross-linking agents include amine compounds, aldehyde compounds, methylol compounds, water-soluble epoxy resins, isocyanate compounds, and polyvalent metal salts. When a polyvinyl alcohol-based resin is used as an adhesive component, an aldehyde compound such as glyoxal, a methylol compound such as methylol melamine, and a water-soluble epoxy resin are preferably used as the cross-linking agent. Here, the water-soluble epoxy resin is a polyamide obtained by reacting a polyamide polyamine, which is a reaction product of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adiponic acid, with epichlorohydrin. It can be an epoxy resin. A commercially available product may be used as the water-soluble epoxy resin, and examples of the commercially available product include "Sumirace Resin 650 (30)" (trade name) sold by Sumika Chemtex Co., Ltd.

The pressure-sensitive adhesive layer can be formed from the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition can be composed of a pressure-sensitive adhesive composition containing a resin as a main component, such as (meth) acrylic-based, rubber-based, urethane-based, ester-based, silicone-based, and polyvinyl ether-based. Among them, a pressure-sensitive adhesive composition using a (meth) acrylic resin having excellent transparency, weather resistance, heat resistance and the like as a base polymer is preferable. The pressure-sensitive adhesive composition may be an active energy ray-curable type or a thermosetting type.

The pressure-sensitive adhesive composition includes a cross-linking agent, a polymerization initiator, a sensitizer, fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, a pressure-sensitive adhesive, and a filler (metal powder). And other inorganic powders), antioxidants, UV absorbers, dyes, pigments, colorants, antifoaming agents, corrosion initiators, photopolymerization initiators and other additives.

<Protective film>
The polarizing plate of the present invention may have a protective film. In one embodiment of the present invention, as shown in FIG. 5, the protective film (6) has an adhesive layer or an adhesive on the surface of the polarizer (1) opposite to the side where the ultraviolet reflective layer (2) is present. It is laminated via the layer (4). As the protective film, for example, cyclic olefin resin, cellulose acetate resin, chain olefin resin, acrylic resin, polyimide resin, polycarbonate resin, polyester resin, etc. have been used as materials for forming a conventional protective film in this field. A thermoplastic resin film formed from a widely used material can be used. Further, an active energy ray-curable resin layer may be laminated as a protective film.

Examples of the monomer constituting the cyclic olefin resin include norbornene. Examples of norbornene substituents include 3-substituted, 4-substituted, 4,5-di-substituted, and dicyclopentadiene, with the double bond position of norbornene at the 1- and 2-positions. And dimethanooctahydronaphthalene can also be monomers constituting the cyclic olefin resin.

The cyclic olefin resin having a norbornene-based monomer as a constituent unit may or may not have a norbornane ring in its main chain. Examples of the norbornene-based monomer forming a cyclic olefin-based resin having no norbornene ring in the main chain include those having a 5-membered ring by ring-opening, typically norbornene, dicyclopentadiene, 1- or 4-methyl. Examples thereof include norbornene and 4-phenylnorbornene. When the cyclic olefin resin is a copolymer, the arrangement state of the molecule is not particularly limited, and it may be a random copolymer, a block copolymer, or a graft copolymer. There may be.

More specific examples of the cyclic olefin resin include a ring-opening polymer of a norbornene-based monomer, a ring-opening copolymer of a norbornene-based monomer and another monomer, and addition of maleic acid and cyclopentadiene to them. Polymer modified products, polymers or copolymers obtained by hydrogenating these, addition polymers of norbornene-based monomers, addition copolymers of norbornene-based monomers and other monomers, and the like. Examples of other monomers used as copolymers include α-olefins, cycloalkenes, and non-conjugated dienes. Among these, the cyclic olefin-based resin is preferably a resin obtained by hydrogenating a ring-opening polymer using a norbornene-based monomer.

As the cyclic olefin resin, a raw film formed from the resin may be used, or may be stretched to form a retardation film. Further, in addition to stretching, a shrinkable film having a predetermined shrinkage rate may be attached and heat-shrinked.

Cyclic olefin resins obtained by polymerizing norbornene-based monomers include "Zeonex (registered trademark)" and "Zeonoa (registered trademark)" sold by Nippon Zeon Co., Ltd., and "Arton (registered trademark)" sold by JSR Corporation. Trademark) ”and so on. Commercially available products of these cyclic olefin resin films and stretched films thereof are also available. For example, "Zeonoa Film (registered trademark)" and JSR sold by Nippon Zeon Co., Ltd. under their trade names. There are "Arton (registered trademark) film" sold by Sekisui Chemical Co., Ltd. and "Scina (registered trademark) retardation film" sold by Sekisui Chemical Industry Co., Ltd.

The protective film for the cyclic olefin resin includes a film made of a mixed resin containing two or more types of the cyclic olefin resin and the olefin resin, and a film made of a mixed resin of the cyclic olefin resin and another thermoplastic resin. Can also be used. For example, examples of the mixed resin containing two or more types of the cyclic olefin resin and the olefin resin include the above-mentioned mixture of the cyclic olefin resin and the chain aliphatic olefin resin. When a mixed resin of a cyclic olefin resin and another thermoplastic resin is used, an appropriate other thermoplastic resin may be selected according to the purpose. Specific examples include polyvinyl chloride resin, cellulose resin, polystyrene resin, acrylonitrile / butadiene / styrene copolymer resin, acrylonitrile / styrene copolymer resin, (meth) acrylic resin, polyvinyl acetate resin, and poly. Vinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene sulfide resin, polysulfone resin, polyether sulfone resin, poly There are ether ether ketone resin, polyarylate resin, liquid crystal resin, polyamideimide resin, polyimide resin, polytetrafluoroethylene resin and the like. Only one type of thermoplastic resin may be used alone, or two or more types may be used in combination. Further, the thermoplastic resin may be used after undergoing any appropriate polymer modification. Examples of polymer modification include copolymerization, cross-linking, molecular end modification, and imparting stereoregularity.

The protective film of the cyclic olefin resin may contain components such as a residual solvent, a stabilizer, a plasticizer, an antiaging agent, an antistatic agent, an ultraviolet absorber, and a leveling agent, if necessary.

The cellulose acetate-based resin film is a film made of a portion of cellulose or a completely acetate esterified product, and examples thereof include a triacetyl cellulose film and a diacetyl cellulose film.

A commercially available product can be used as the cellulose acetate-based resin film. Suitable commercial products include "Fujitac (registered trademark) TD80", "Fujitac (registered trademark) TD80UF", "Fujitac (registered trademark) TD80UZ" sold by Fujifilm Co., Ltd., and Konica Minolta Opto Co., Ltd. Examples thereof include "KC8UX2M" and "KC8UY" (all of which are trade names).

The chain olefin resin is a polymer containing a chain olefin such as ethylene or propylene as a main monomer, and may be a homopolymer or a copolymer. Of these, a homopolymer of propylene and a copolymer in which a small amount of ethylene is copolymerized with propylene are preferable.

The acrylic resin is a polymer containing methyl methacrylate as a main monomer, and may be a copolymer of methyl methacrylate, or methyl methacrylate and an acrylic acid ester such as methyl acrylate. It may be a copolymer of.

A polyimide resin is a polymer having an imide bond in the main chain, and is obtained by polymerizing tetracarboxylic acid dianhydride and diamine to obtain polyamic acid (polyamic acid), which is a precursor of polyimide, and then dehydration and cyclization. Examples thereof are those obtained by the (imidization) reaction.

The polycarbonate resin is a polymer having a carbonate bond in the main chain, and examples thereof include those obtained by condensation polymerization of bisphenol A and phosgene.

The polyester resin is a polymer obtained by condensation polymerization of a dibasic acid and a dihydric alcohol, and examples thereof include polyethylene terephthalate.

Further, the surface of the protective film opposite to the polarizer may be subjected to surface treatment such as antiglare treatment, hard coat treatment, antistatic treatment, antireflection treatment, etc., and has a liquid crystal compound or other high molecular weight. A coat layer made of a compound or the like may be formed.

The thickness of the protective film is usually 2 to 100 μm, preferably 3 to 80 μm, more preferably 50 μm or less, and particularly preferably 30 μm or less. When the thickness of the protective film is at least the above lower limit, sufficient strength can be ensured, and the protective film has excellent workability. Further, when the thickness is not more than the above upper limit, a lightweight and thin polarizing plate can be obtained without lowering the transparency.

In the polarizing plate of the present invention, the adhesive or the pressure-sensitive adhesive composition constituting the adhesive layer or the pressure-sensitive adhesive layer for adhering the protective film to the polarizer or the like is for adhering the above-mentioned ultraviolet reflective layer and the polarizer. Examples are similar to those used. When a plurality of adhesive layers and / or pressure-sensitive adhesive layers are provided as the layers constituting the polarizing plate of the present invention, they may be the same as or different from each other.

The polarizing plate of the present invention is further laminated with an optical film or an optical layer such as a retardation film, a viewing angle compensation film, a brightness improving film, an antiglare film, an antireflection film, and / or a condensing film, if necessary. You may be. These optical films and optical layers may be bonded to the polarizing plate via the adhesive layer or the pressure-sensitive adhesive layer made of the above-mentioned adhesive or pressure-sensitive adhesive.

Further, in one embodiment of the present invention, the polarizing plate has an adhesive layer (7) via a protective film (6) on the side of the polarizing element (1) opposite to the side where the ultraviolet reflecting layer (2) is present. It may be a polarizing plate with a pressure-sensitive adhesive layer (see FIG. 5). In this case, the thickness of the pressure-sensitive adhesive layer is usually 3 to 30 μm, preferably 5 to 25 μm. The polarizing plate of the present invention can be attached to an image display element (8) such as a liquid crystal cell via the pressure-sensitive adhesive layer.

<Front plate>
In the polarizing plate with a front plate of the present invention, the front plate to be bonded to the polarizing plate of the present invention is preferably an optically transparent front plate. Here, optically transparent means having a transmittance of 85% or more in a wavelength range ranging from 460 to 720 nm. The thickness of the front plate is usually about 0.5 to 5 mm. Further, the refractive index of the front plate is preferably close to the refractive index of the ultraviolet cured product layer and / or the liquid crystal panel formed on the outermost layer of the polarizing plate of the present invention and in contact with the front plate, and 1.4 to 1. It is preferably 7. Due to the close refractive index of the front plate and the ultraviolet cured product layer and / or the liquid crystal panel, reflection and light scattering at the interface between the front plate and / or the liquid crystal panel and the polarizing plate can be reduced and visibility can be improved. it can.

The front plate may be a glass front plate or a resin front plate. Examples of the glass forming the glass front plate include borosilicate and soda lime. Specific examples thereof include EAGLE XG (registered trademark) (Corning Inc.) and JADE (registered trademark) (Corning Inc.). Examples of the resin front plate include a polyester film such as polyethylene terephthalate, an acrylic film such as a borocarbonate film and a polymethylmethacrylate film, and the like.

The front plate may be a touch panel. A conventionally known touch panel can be adopted, and usually includes a conductive layer arranged between two transparent front plates. Examples of the two transparent front plates include the above-mentioned glass front plate, and examples of the conductive layer include indium tin oxide.

<Manufacturing method of polarizing plate>
In the polarizing plate of the present invention, a layer of an ultraviolet curable composition is formed on one surface of an ultraviolet reflective layer, and ultraviolet rays are irradiated from the side of the ultraviolet reflecting layer on which the layer of the ultraviolet curable composition is formed. It can be produced by curing the ultraviolet curable composition. Therefore, in one embodiment of the present invention, the method for producing a polarizing plate of the present invention is to form a layer of an ultraviolet curable composition on one surface of an ultraviolet reflecting layer, and the ultraviolet rays of the ultraviolet reflecting layer. It comprises irradiating ultraviolet rays from the side where the layer of the curable composition is formed to cure the ultraviolet curable composition.

The layer of the UV curable composition can be formed by applying the UV curable composition on the UV reflective layer. As a method of applying the ultraviolet curable composition on the ultraviolet reflective layer, known methods such as die coating, knife coating, and curtain coating can be adopted.

After applying the ultraviolet curable composition to form a layer of the ultraviolet curable composition, the ultraviolet curable composition is irradiated with ultraviolet rays from the side of the ultraviolet reflective layer on which the layer of the ultraviolet curable composition is formed. A UV-cured product layer can be obtained by curing. By irradiating ultraviolet rays from the side of the ultraviolet reflective layer on which the layer of the ultraviolet curable composition is formed, in addition to the ultraviolet rays that can be directly used for curing the layer of the ultraviolet curable composition, the layer of the ultraviolet curable composition The ultraviolet rays transmitted through and reflected by the ultraviolet reflective layer can be used for curing the ultraviolet curable composition, and an ultraviolet cured product layer having high adhesion can be obtained.

When the front plate and the polarizing plate are bonded to each other by the ultraviolet curable layer, the ultraviolet curable composition is applied to the ultraviolet reflective layer and / or the front plate, and the two are bonded to each other to form an ultraviolet curable composition on the ultraviolet reflective layer. It suffices to obtain a bonded body in which a layer of an object is formed. At this time, the ultraviolet curable composition may be applied to the entire surface of the ultraviolet reflecting layer and / or the surface of the front plate to be bonded to each other, or one of the adhesive surfaces of the ultraviolet reflecting layer and / the front plate. It may be coated so as to leave an unpainted portion on the portion. Examples of the method of applying the ultraviolet reflective layer and / or the entire surface of the adhesive surface of the front plate include a method of applying the ultraviolet curable composition so as to be in contact with the end portion and the side surface of the polarizing plate. As a method of coating so as to leave an unpainted portion on a part of the adhesive surface of the UV reflective layer and / the front plate, for example, an uncoated portion is applied to the end of the adhesive surface of the UV reflective layer and / the front plate. There is a way to leave it.

The polarizing plate with a front plate of the present invention can be obtained by forming a layer of an ultraviolet curable composition on an ultraviolet reflective layer by the above method and then irradiating the front plate with ultraviolet rays. At this time, in order to adjust the thickness of the obtained ultraviolet cured product layer, the distance between the polarizing plate and the front plate may be maintained by a support rod, a spacer, or the like.

The light source for the curing treatment of the ultraviolet curable composition is not particularly limited as long as it is a light source that generates ultraviolet rays. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, and a metal halide lamp. A lamp, a xenon lamp, or the like can be used.

The irradiation conditions may be appropriately determined according to the light source to be used. The irradiation amount of ultraviolet rays is usually an integrated light amount of 1000 to 10000 mJ / cm ² , preferably 2000 to 6000 mJ / cm ² . By irradiating ultraviolet rays from the layer side of the ultraviolet curable composition, it is possible to generate a sufficient amount of active species of the polymerization initiator with a small irradiation amount by utilizing the ultraviolet rays reflected by the ultraviolet reflecting layer. Adhesion of the polarizing plate and the like is improved. It is also advantageous in that the irradiation time of ultraviolet rays can be shortened and the productivity can be improved.

In one embodiment of the present invention, in the polarizing plate of the present invention, a layer of an ultraviolet curable composition is formed on one surface of a polarizing element, an ultraviolet reflecting layer is laminated on the layer, and the polarizing element side is formed. It can be produced by irradiating the ultraviolet curable composition with ultraviolet rays to cure the ultraviolet curable composition. Therefore, in one embodiment of the present invention, in the method for producing a polarizing plate of the present invention, a layer of an ultraviolet curable composition is formed on one surface of a polarizer, and an ultraviolet reflective layer is laminated on the layer. This includes irradiating ultraviolet rays from the polarizer side to cure the ultraviolet curable composition.

In the polarizing plate of the present invention, when the polarizer and the ultraviolet reflective layer and / or the protective film are adhered with an adhesive or an adhesive, the ultraviolet reflective layer or the protective film attached to the polarizer and / or the protective film thereof. An adhesive or an adhesive may be applied to the adhesive surface, the two may be bonded together, and then the adhesive or the adhesive may be cured. The curing conditions of the adhesive or the pressure-sensitive adhesive may be appropriately determined according to the type of the adhesive or the pressure-sensitive adhesive used. Prior to bonding, it is also effective to apply an easy-adhesion treatment such as a saponification treatment, a corona discharge treatment, a plasma treatment or a primer treatment to the ultraviolet reflective layer or the protective film to improve the wettability.

For example, when the polarizer and the ultraviolet reflective layer are adhered to each other by using an ultraviolet curable adhesive, the same method and conditions as those for curing the layer of the ultraviolet curable composition described above are adopted from the polarizer side. It may be cured by irradiating with ultraviolet rays. When the polarizer and the protective film are adhered to each other in the embodiment shown in FIG. 5, which is one embodiment of the present invention, either the polarizer side or the protective film side is used as long as the irradiation is not hindered by the ultraviolet reflective layer. You may irradiate from.

When an active energy ray-curable adhesive other than ultraviolet rays (for example, an electron beam-curable adhesive) is used, irradiation may be performed from either the ultraviolet reflection layer side or the protective film side or the polarizer side. When an electron beam-curable adhesive is used, for example, the methods described in JP2013-174922A (paragraphs [0013] and [0014]) can be used as the electron beam irradiation method.

When a water-based adhesive is used, it may be cured by drying the water-based adhesive. The drying treatment can be carried out at, for example, about 50 to 100 ° C. and about 0.5 to 10 (minutes). After the drying treatment, curing at a temperature slightly higher than room temperature, for example, about 30 to 50 ° C. for about 1 to 10 days is preferable in order to further enhance the adhesive strength.

To integrate the polarizing plate of the present invention or the polarizing plate with a front plate of the present invention and the image display cell, for example, an adhesive layer is provided on the outermost layer of the polarizing plate on the image display cell side, and the polarizing plate is bonded through the adhesive layer. The image display device of the present invention can be provided.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Unless otherwise specified, "parts" in Examples and Comparative Examples represent "parts by mass".

<Measurement of UV average reflectance>
Using MPC-2200 (manufactured by Shimadzu Corporation) connected to a spectrophotometer UV2450, each ultraviolet reflective film was irradiated with light having a wavelength of 280 to 380 nm every 2 nm, and the light reflected in the front direction was measured. The average value of the measurement results for every 2 nm was taken as the reflectance.

<Measurement of UV transmittance>
Using a spectrophotometer U4100 (manufactured by Shimadzu Corporation), each ultraviolet reflective film was irradiated with light having a wavelength of 280 to 380 nm every 2 nm, and the light transmitted through the film was measured. The average value of the measurement results for each 2 nm was taken as the ultraviolet transmittance.

<Measurement of visible light transmittance>
Using a spectrophotometer U4100 (manufactured by Shimadzu Corporation), each ultraviolet reflective film was irradiated with light having a wavelength of 460 to 720 nm every 2 nm, and the light transmitted through the film was measured. The average value of the measurement results for each 2 nm was defined as the visible light transmittance.

1. 1. Example 1
(1) Preparation of Polarizer A polyvinyl alcohol film having an average degree of polymerization of about 2400, a saponification degree of 99.9 mol% or more and a thickness of 20 μm was uniaxially stretched about three times by a dry method, and further maintained in a tense state. After immersing in pure water at 60 ° C. for 1 minute, it was immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C. for 60 seconds. Then, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, the mixture was washed with pure water at 26 ° C. for 20 seconds and then dried at 65 ° C. to obtain a polarizer (thickness: 7 μm) in which iodine was adsorbed and oriented on polyvinyl alcohol.

(2) Preparation of water-based adhesive In 100 parts of water, 3 parts of carboxyl group-modified polyvinyl alcohol [“KL-318” obtained from Kuraray Co., Ltd.] was dissolved, and the aqueous solution was dissolved in a polyamide epoxy resin which is a water-soluble epoxy resin. 1.5 parts of an additive [trade name "Smiley's Resin (registered trademark) 650 (30)" obtained from Taoka Chemical Industry Co., Ltd., an aqueous solution having a solid content concentration of 30%] was added to prepare an aqueous adhesive.

(3) Preparation of Polarizing Plate Using the aqueous adhesive, a protective film (manufactured by Nippon Zeon Corporation) of an unstretched cyclic olefin resin having an in-plane retardation value of 0 nm and a thickness of 13 μm was applied to the polarizing element. A single-sided polarizing plate was obtained by laminating on one side of the above. Prior to bonding, the bonding surface of the protective film of the cyclic olefin resin was subjected to a corona discharge treatment. After bonding, the single-sided polarizing plate was dried at 80 ° C. for 5 minutes and further cured at 40 ° C. for 168 hours.

To an ultraviolet reflective film (thickness 13 μm, ultraviolet average reflectance 25.0%, ultraviolet average transmittance 2.1%, visible light transmittance 90%) similar to the display film described in JP-A-2015-194566. , UV curable adhesive (“Aronix” manufactured by Toa Synthetic Co., Ltd.) was applied and bonded to the polarizer side of the single-sided polarizing plate. Then, ultraviolet rays were irradiated from the protective film side to cure the adhesive to obtain a polarizing plate 1. The ultraviolet irradiation was carried out so that the integrated light intensity in the wavelength range of 260 nm to 320 nm was 200 mJ / cm ^2.

The obtained polarizing plate 1 was cut into a width of 25 mm and a length of 120 mm so that the absorption axis of the polarizer was in the long side direction to obtain a strip-shaped polarizing plate 1.

The strip-shaped polarizing plate 1 is placed on a separate film 120 mm × 200 mm so that the protective film side is in contact with the separate film, and the ultraviolet curable photoelastic resin (model number: SVR1320) manufactured by Dexerials America Corporation is placed on the strip-shaped polarizing plate 1. ) Was applied in an amount such that the thickness after curing was 100 μm. Soda glass of the same size as the separate film was prepared and laminated on the ultraviolet curable photoelastic resin so as to sandwich the strip-shaped polarizing plate 1 and the ultraviolet curable photoelastic resin. Next, ultraviolet rays were irradiated from the soda glass side to cure the ultraviolet curable photoelastic resin, and the polarizing plate and the soda glass were adhered to each other. The ultraviolet irradiation was carried out so that the integrated light amount in the wavelength range of 315 nm to 400 nm was 5000 mJ / cm ^2. Further, the ultraviolet curable material layer made of the ultraviolet curable photoelastic resin had an average ultraviolet reflectance of 6.4% and a visible light transmittance of 91.3%.

(4) Evaluation of adhesion The separate film was peeled off from the obtained polarizing plate with soda glass, and a 180 ° peel test was performed at a peeling speed of 300 mm / min using Autograph AGS-50NX (manufactured by Shimadzu Corporation). The adhesion between the polarizing plate and the soda glass was measured. The result was 13.2 N / 25 mm, and the adhesion was good.

2. Example 2
An ultraviolet reflective film (thickness 13 μm, ultraviolet average reflectance 31.5%, ultraviolet average transmittance 11.4%, visible light transmittance 91%) similar to the display film described in JP-A-2015-194566. A polarizing plate 2 was produced in the same manner as in Example 1 except that it was used, and the adhesion was evaluated. As a result, since the reflectance of the ultraviolet reflective film is higher than that of Example 1, the adhesion is 13.2 N / 25 mm or more.

3. 3. Comparative Example 1
Product name "25KCHCN-TC" (made by Toppan TOMOEGAWA Optical Film Co., Ltd., thickness 32 μm) with a hard coat layer (cured product layer of UV curable resin) applied to TAC (triacetyl cellulose film) instead of UV reflective film The polarizing plate 3 was produced in the same manner as in Example 1 except that the ultraviolet reflectance was 4.7% and the visible light transmittance was 91%), and the adhesion was evaluated. The result was 6.6 N / 25 mm, which was lower than that of Examples 1 and 2.

1: Polarizer 2: UV reflective layer 3: UV cured product layer 4: Adhesive layer or adhesive layer 5: Front plate 6: Protective film 7: Adhesive layer 8: Image display element 10: Polarizing plate 20: Front plate Polarizing plate with

Claims (4)

Includes a polarizer and UV-reflecting layer comprises a cured product layer composed of a cured product of the ultraviolet curable composition on at least one surface of the ultraviolet reflecting layer, before Kihen photons a vibration plane parallel to the optical axis It is provided with a polarizing plate having a property of absorbing linearly polarized light and transmitting linearly polarized light having a vibrating surface orthogonal to the optical axis, and a front plate.
The front plate is laminated on the surface of the cured product layer opposite to the polarizer side.
The cured product layer is laminated on the surface of the ultraviolet reflecting layer opposite to the polarizer side.
Polarizing plate with front plate . A cured product layer composed of a cured product of the ultraviolet curable composition is provided on a surface of the ultraviolet reflecting layer opposite to the polarizer side, and the ultraviolet reflecting layer is provided via an adhesive layer or an adhesive layer. The polarizing plate with a front plate according to claim 1, which is laminated on a polarizing element. The ultraviolet reflective layer is laminated on a polarizer via an adhesive layer, and the adhesive layer is an adhesive selected from the group consisting of an ultraviolet curable adhesive, an electron beam curable adhesive, and a water-based adhesive. The polarizing plate with a front plate according to claim 2, which is a cured product layer. An image display device comprising a front plate with the polarizing plate according to claim 1.

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