JP6825848B2 - Polarizing plate for curved image display panel - Google Patents

Description

The present invention relates to a polarizing plate used for a curved image display panel and a curved image display panel including the polarizing plate.

Conventionally, as a polarizing plate used in various image display panels such as a liquid crystal display panel and an organic electroluminescence (organic EL) display panel, a dichroic dye such as iodine or a dichroic dye is oriented on a polyvinyl alcohol-based resin film. A polarizing plate having a structure in which a protective film such as a triacetyl cellulose film is laminated on one side or both sides of the adsorbed polarizing film via an adhesive layer is known (for example, Patent Documents 1 to 3). Such a polarizing plate is attached to an image display element such as a liquid crystal cell or an organic EL display element in a form in which various optical layers such as a retardation film and an optical compensation film are further laminated as needed to display an image. Make up the panel.

Japanese Unexamined Patent Publication No. 2010-21196 Japanese Unexamined Patent Publication No. 10-062624 Japanese Unexamined Patent Publication No. 07-134212

In recent years, studies have been conducted on image display devices having various shapes from the viewpoint of design. In particular, the difference in distance from the viewer to the center of the screen and the side edges is small, and a feeling of immersion in the screen can be obtained. Therefore, interest in curved image display devices such as curved LCD TVs is increasing, and various types are available. Product development is being done.

In the curved surface image display device, it is necessary to use a polarizing plate as in the plane image display device, but in order to manufacture the curved surface image display device, a conventional polarizing plate as disclosed in Patent Documents 1 to 3 is used. When used for a curved surface display panel, the polarizing plate may peel off or float from the curved surface display panel with the passage of time. In the curved surface display panel, peeling or floating of the polarizing plate is particularly likely to occur on the concave surface side (visual recognition side), which leads to display failure in the viewing area. Further, the occurrence of peeling and floating of the polarizing plate from the curved surface display panel becomes particularly remarkable in a high temperature environment. For this reason, there is a possibility that more serious peeling or floating may occur when the light source is exposed to the heat for a long time due to long-term use, during transportation where a hot and humid environment is likely to occur, or depending on the area where the light source is used.

Therefore, the present invention solves the above-mentioned problems that may occur peculiarly to the polarizing plate used for the curved image display panel, and is peeled off or lifted from the curved display panel even after long-term use and / or use in a high temperature environment. It is an object of the present invention to provide a polarizing plate for a curved image display panel capable of suppressing the above.

The present invention provides the following preferred embodiments [1] to [8].
[1] A polarizing plate used for a curved image display panel having an average radius of curvature R (mm) and a thickness H (mm) and having a horizontal length of L1 (mm) in a flat state.
The polarizing plate thickness H1 (mm) on the concave side when attached to the curved image display panel is the following formula (1):
L1 (H + H1) / 2R ≦ 0.4 (1)
A polarizing plate that satisfies the above conditions.
[2] The polarizing plate according to the above [1], wherein the thickness H of the curved image display panel is 0.4 mm or more.
[3] The polarizing plate according to the above [1] or [2], wherein the dimensional change rate after 250 hours under drying at 80 ° C. is 3% or less.
[4] The polarizing plate according to any one of [1] to [3] above, wherein the polarizing film in the polarizing plate is a stretched and dyed polyvinyl alcohol film.
[5] The polarizing plate according to any one of [1] to [4] above, wherein the curved image display panel has an average radius of curvature R of 900 to 7000 mm.
[6] The polarizing plate according to any one of [1] to [5] above, wherein the horizontal length L1 of the polarizing plate in a flat state is 500 mm or more.
[7] A curved image display panel including a concave-side polarizing plate and a convex-side polarizing plate, wherein the concave-side polarizing plate is the polarizing plate according to any one of the above [1] to [6]. ..
[8] A curved image display panel including a concave-side polarizing plate and a convex-side polarizing plate, wherein the concave-side polarizing plate and the convex-side polarizing plate are the polarizing plates according to any one of [1] to [6]. , Curved image display panel.

According to the present invention, it is possible to provide a polarizing plate for a curved image display panel that can suppress peeling and floating from a display panel in a curved state even when used for a long period of time and / or in a high temperature environment.

It is a schematic diagram of the curved surface image display panel for explaining the mean radius of curvature. A cross-sectional view of an image display panel in a curved surface state including a polarizing plate is shown. A cross-sectional view showing a structure of a polarizing plate and a structure which is one aspect of a curved image display panel is shown. An example of the absorption axis direction of the polarizing plate in the curved surface image display device is shown. An example of the absorption axis direction of the polarizing plate in the curved surface image display device is shown.

Hereinafter, embodiments of the present invention will be described in detail.
In the present invention, the "planar state" means a state in which the entire surface is flat without including the curved portion. Further, the "curved surface state" generally means a state in which the entire surface is curved by one arc, and a case in which a curved surface is formed as a whole including a curved portion formed by one or a plurality of arcs. In the present invention, the "average radius of curvature" is the average value of the radii of curvature at the three points of the left and right ends and the center of the image display panel. That is, in FIG. 1, the mean radius of curvature is a value calculated by (R _left + R _middle + R _right ) / 3.

The present invention relates to a polarizing plate used for a curved image display panel having an average radius of curvature R (mm) and a thickness H (mm). The polarizing plate of the present invention has a horizontal length of L1 (mm) in a flat state, and the thickness H1 (mm) of the polarizing plate on the concave surface side when attached to the curved image display panel is as follows. (1):
L1 (H + H1) / 2R ≦ 0.4 (1)
Meet. In the present invention, the concave side means the side corresponding to the viewing side of the curved image display panel, and the convex side means the side facing the concave side.

Here, a polarizing plate having the same horizontal length and thickness H1 is bonded on an image display panel having a horizontal length L1 and a thickness H in a flat state, and an average radius of curvature R (here, here). R is defined as the radius to the center of the panel thickness) (see FIG. 2), the length of the central portion of the panel is the reference, so it does not change. On the other hand, the horizontal length of the polarizing plate after being curved (defined as the length at the center of the polarizing plate thickness) is calculated as the length of an arc having a radius of curvature {R- (H + H1) / 2}. To. The present inventors have found that the change from L1 to this length is important for solving the problems of the present invention. From this, in the present invention, the following equation, which is the above-mentioned amount of change:
L1-L1 {R- (H + H1) / 2} / R = L1 (H + H1) / 2R
It is important to keep the amount low, that is, to set it to 0.4 or less in order to suppress peeling and floating of the polarizing plate.

The value of L1 (H + H1) / 2R in the formula (1) is 0.40 or less, preferably 0.38 or less, more preferably 0.35 or less, and even more preferably 0.30 or less. When the value of L1 (H + H1) / 2R in the formula (1) is not more than the above upper limit value, the polarizing plate is further peeled off or lifted from the curved image display panel even after long-term use or use in a high temperature environment. Hard to occur. The value of L1 (H + H1) / 2R in the formula (1) is usually 0.01 or more.
Is.

The curved image display panel is usually not curved in the vertical direction (vertical direction), so that the viewer side is concave in the horizontal direction (horizontal direction) and the opposite side (backlight unit, etc. side) is convex. It is a curved shape and forms a part of a cylinder whose central axis is in the vertical direction (vertical direction).

The curved image display panel preferably has a thickness H of 0.4 mm or more, more preferably 0.8 mm or more, still more preferably 1.0 mm or more. When the thickness H of the curved surface image display panel is equal to or larger than the above lower limit value, various materials can be used as the members used for the curved surface image display panel, and handling becomes easy even when the display panel is enlarged. Therefore, it is industrially advantageous. The thickness H of the curved image display panel is usually 2.0 mm or less.

The curved image display panel preferably has an average radius of curvature R of 7000 mm or less, more preferably 6600 mm or less, still more preferably 5000 mm or less, even more preferably 4000 mm or less, and particularly preferably 3000 mm or less. The curved image display panel has, for example, an average radius of curvature R of 300 mm or more, preferably 900 mm or more, more preferably 1000 mm or more, still more preferably 1200 mm or more. The curved image display panel preferably has an average radius of curvature R of 900 to 7000 mm, more preferably 1000 to 6600 mm. When the average radius of curvature R of the curved image display panel is not more than the above upper limit value, the difference in the distance from the viewer to the center of the screen and the edge of the screen becomes smaller, and a feeling of immersion in the screen can be further obtained. .. When the average radius of curvature R of the curved image display panel is equal to or greater than the above lower limit value, peeling or floating of the polarizing plate from the curved image display panel due to long-term use or use in a high temperature environment is further suppressed.

The average radius of curvature R of the curved image display panel also changes depending on the equipment used. For example, in the case of a device having a small display such as a personal computer or a mobile device, the average radius of curvature R is often smaller (the curvature rate is larger). Further, a device having a large display such as a curved display television may also try to reduce the average radius of curvature R to further enhance the immersive feeling. The polarizing plate of the present invention is excellent in the effect of suppressing peeling and floating of the polarizing plate from the display panel even when used for a long period of time in a state where the average radius of curvature R is small and / or in a high temperature environment. It can be used for a curved image display panel having an average radius of curvature R of ~ 7000 mm, particularly 900 to 5000 mm, and further 1000 to 4000 mm.

The polarizing plate of the present invention has a horizontal length L1 in a planar state of preferably 500 mm or more, more preferably 700 mm or more, still more preferably 1100 mm or more, still more preferably 1400 mm or more. When the horizontal length L1 of the polarizing plate of the present invention in the planar state is equal to or greater than the above lower limit value, the applicable curved image display panel has a large horizontal length, and a feeling of immersion in the screen can be further obtained. it can. Further, the polarizing plate of the present invention usually has a horizontal length L1 of 2500 mm or less in a flat state. The horizontal direction of the polarizing plate coincides with the horizontal direction of the curved surface image display device including the curved surface image display panel, and the vertical direction of the polarizing plate is a direction orthogonal to the horizontal direction. The vertical length of the polarizing plate of the present invention in the planar state is determined by the horizontal length L1 and the aspect ratio of the curved image display panel.

When a conventional polarizing plate is used for manufacturing a curved image display panel, there is an increased risk that the polarizing plate will peel off or float from the curved image display panel even in a normal temperature environment for a long period of time. Long-term lighting and use in a high-temperature environment further promote the occurrence of peeling and floating of the polarizing plate from the curved image display panel. The reason for this is not bound by a specific theory, but is considered to be due to the horizontal strain / compressive stress caused by the curved surface of the polarizing plate. In order to suppress this strain / compressive stress, it is possible to change the thickness H1 of the polarizing plate according to the average radius of curvature R, the thickness H, and the length L1 in the horizontal direction of the curved image display panel. It is thought that it is effective in suppressing the peeling and floating of the polarizing plate from the surface. In the present invention, the suppression of peeling and floating of the polarizing plate is achieved by determining the thickness H1 of the polarizing plate so as to satisfy the above formula (1).

The polarizing plate of the present invention has a dimensional change rate of preferably 3.0% or less, more preferably 2.0% or less, still more preferably 1.5% or less after 250 hours under drying at 80 ° C. When the dimensional change rate of the polarizing plate is equal to or less than the upper limit value, the shrinkage and / or expansion of the polarizing plate can be suppressed during long-term use or in a high temperature environment. Therefore, polarization from the image display panel in a curved state Peeling and floating of the board are less likely to occur. The dimensional change rate of the polarizing plate is usually 0% or more.

The dimensional change rate can be controlled by suppressing the dimensional change of the polarizing film that contributes to the contraction and expansion of the polarizing plate. The dimensional change of the polarizing film can be controlled, for example, by changing the manufacturing conditions and types such as the draw ratio of the polarizing film, or by increasing the rigidity of the protective layer adjacent to the polarizing film. Specifically, the dimensional change can be controlled by setting the draw ratio to preferably 8 times or less, more preferably 7.5 times or less, still more preferably 7 times or less.

The dimensional change rate is calculated by cutting a polarizing plate into a size of 100 mm x 100 mm, measuring the initial size and the size 250 hours after drying at 80 ° C. without attaching them to glass, and comparing them. Can be done. As a matter of course, the dimensional change rate when the glass is bonded to the glass via the adhesive is smaller than the dimensional change rate when the glass is not bonded as described above. Although it depends on the type of adhesive, the dimensional change rate when the glass is not bonded is usually about 1/2 to 1/15.

The polarizing plate of the present invention is not limited as long as it is configured to have a function normally possessed as a polarizing plate. For example, in a preferred embodiment, one side of a polarizing film or a polarizing film Alternatively, it includes a protective layer laminated on both sides via an adhesive, an adhesive layer for bonding to an image display element, and optionally an optical layer.

In one embodiment of the invention, the polarizing plate is composed of a protective layer, a polarizing film, a protective layer and an adhesive layer, and optionally an optical layer. Here, the polarizing film and the protective layer are laminated via an adhesive.

The configuration of the polarizing plate of the present invention and the curved image display panel in one embodiment will be described with reference to FIG. 3. The polarizing plate of the present invention has an adhesive layer (10) in order from the layer adjacent to the image display element (3). , Protective layer (11), polarizing film (12), protective layer (11) and, if necessary, an optical layer (not shown) are laminated. Normally, the polarizing film (12) and the protective layer (11) are laminated via an adhesive. Further, in one embodiment of the present invention, the curved surface image display panel of the present invention has a concave-side polarizing surface bonded to the image display element (3) via the image display element (3) and the adhesive layer (10), respectively. It is composed of a plate (1) and a convex side polarizing plate (2). In one embodiment of the present invention, the concave polarizing plate (1) has an adhesive layer (10), a protective layer (11), a polarizing film (12), and a protective layer in order from the layer adjacent to the image display element (3). It is composed of (11) and, if necessary, a surface treatment layer (13) and / or an optical layer, and the convex side polarizing plate (2) is formed of an adhesive layer (10) in order from a layer adjacent to the image display element (3). , A protective layer (11), a polarizing film (12), a protective layer (11) and, if necessary, an optical layer.
Hereinafter, each component of the polarizing plate of the present invention will be described in detail.

<Adhesive layer>
As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, conventionally known pressure-sensitive adhesives can be used without particular limitation. For example, a pressure-sensitive adhesive having a base polymer such as acrylic, rubber, urethane, silicone, or polyvinyl ether can be used. Can be used. Further, it may be an energy ray-curable pressure-sensitive adhesive, a thermosetting pressure-sensitive adhesive, or the like. Among these, an adhesive using an acrylic resin as a base polymer, which is excellent in transparency, adhesive strength, reworkability, weather resistance, heat resistance, etc., is preferable.

The acrylic pressure-sensitive adhesive is not particularly limited, but (meth) such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Acrylic acid ester-based base polymers and copolymer-based base polymers containing two or more of these (meth) acrylic acid esters and the like are preferably used. Furthermore, polar monomers are copolymerized in these base polymers. Examples of the polar monomer include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, 2-N, N-dimethylaminoethyl (meth). 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 acrylate and glycidyl (meth) acrylate.

These acrylic pressure-sensitive adhesives can be used alone, but are usually used in combination with a cross-linking agent. The cross-linking agent is a divalent or polyvalent metal ion that forms a carboxylic acid metal salt with a carboxyl group, a polyamine compound that forms an amide bond with a carboxyl group, and the like. Examples thereof include polyepoxy compounds and polyol compounds that form an ester bond with a carboxyl group, and polyisocyanate compounds that form an amide bond with a carboxyl group. Among them, polyisocyanate compounds are widely used.

The energy ray-curable adhesive has the property of being cured by being irradiated with energy rays such as ultraviolet rays and electron beams, and has adhesiveness even before irradiation with energy rays to be applied to an adherend such as a film. It is an adhesive having the property of being in close contact and being cured by irradiation with energy rays to adjust the adhesion. As the energy ray-curable pressure-sensitive adhesive, it is particularly preferable to use an ultraviolet-curable pressure-sensitive adhesive. The energy ray-curable pressure-sensitive adhesive generally contains an acrylic pressure-sensitive adhesive and an energy ray-polymerizable compound as main components. Usually, a cross-linking agent is further added, and if necessary, a photopolymerization initiator, a photosensitizer, or the like can be added.

In addition to the above-mentioned base polymer and cross-linking agent, the pressure-sensitive adhesive layer may be made of, for example, a natural product or a synthetic product in order to adjust the pressure-sensitive adhesive strength, cohesive power, viscosity, elasticity, glass transition temperature, etc. of the pressure-sensitive adhesive, if necessary. Even if it contains additives such as certain resins, tackifying resins, antioxidants, antistatic agents, UV absorbers, dyes, pigments, defoaming agents, corrosive agents, photopolymerization initiators, thermal polymerization initiators, etc. Good. Further, it is also possible to form an adhesive layer that contains fine particles and exhibits light scattering properties. Examples of the ultraviolet absorber include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex salt compounds.

In the present invention, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer preferably contains a silane-based compound, and in particular, it is preferable to contain the silane-based compound in the acrylic resin before blending the cross-linking agent. Since the silane compound improves the adhesive strength to the glass, the inclusion of the silane compound improves the adhesion between the image display element sandwiched between the glass substrates and the adhesive layer, and secures a high adhesive strength to the display panel. Therefore, even when used for a long period of time and / or in a high temperature environment, peeling or floating from the curved display panel is less likely to occur.

The adhesive layer may be provided by a method in which, for example, the above-mentioned adhesive is used as an organic solvent solution, applied by a die coater or a gravure coater on a film or layer (for example, a polarizing film) on which the adhesive is to be laminated, and dried. it can. It can also be provided by a method of transferring a sheet-like adhesive formed on a plastic film (called a separate film) that has been subjected to a mold release treatment to a film or layer to be laminated. The thickness of the adhesive layer is not particularly limited, but is preferably in the range of 2 to 40 μm, more preferably in the range of 5 to 35 μm, and further preferably in the range of 10 to 30 μm. .. When the thickness of the adhesive layer is at least the above lower limit value, it is possible to further suppress the occurrence of peeling and floating due to long-term use and / or use in a high temperature environment. When the thickness of the adhesive layer is not more than the above upper limit, the increase in the thickness of the polarizing plate is suppressed, and as a result, the adhesive layer is less likely to be deformed in a curved surface state, and peeling due to long-term use and / or use in a high temperature environment. The occurrence of floating can be suppressed. As a result, deterioration of the display function around the frame of the image display device can be suppressed.

In a preferred embodiment, the adhesive layer of the polarizing plate of the present invention is an acrylic resin or silane which is a copolymer of butyl acrylate, methyl acrylate, 2-phenoxyethyl acrylate, 2-hydroxyethyl acrylate and acrylic acid. It is composed of a system compound and an isocyanate compound as a cross-linking agent.

In a preferred embodiment, the polarizing plate of the present invention comprises an adhesive layer. The adhesive strength against glass (hereinafter, may be referred to as "adhesive strength against glass (flat surface, 23 ° C.)" measured in a flat state at 23 ° C. and 50% RH) of the adhesive layer is preferably 1. It is 0N / 25mm or more, more preferably 2.0N / 25mm or more. When the adhesive force against glass (flat surface, 23 ° C.) of the adhesive layer is 1.0 N / 25 mm or more, a curved surface image is used for a long period of continuous use, long-term use and / or use in a high temperature environment, movement and storage, etc. It is possible to more effectively suppress the peeling and floating of the polarizing plate from the display panel. In the polarizing plate of the present invention, the adhesive force against glass (flat surface, 23 ° C.) is more preferably 3.0 N / 25 mm or more, and particularly preferably 4.0 N / 25 mm or more.

Further, in the polarizing plate of the present invention, the adhesive force against glass of the adhesive layer measured in a curved surface state (hereinafter, may be referred to as "adhesive force against glass (curved surface, 23 ° C.)") is 1.5 N / 25 mm. Above, more preferably 2.5 N / 25 mm or more. The adhesive force against glass (curved surface, 23 ° C.) of the polarizing plate of the present invention is more preferably 3.5 N / 25 mm or more, and further preferably 4.5 N / 25 mm or more. The adhesive force against glass measured in the curved surface state is not necessarily the same as the adhesive force against glass measured in the flat state, and does not change according to a certain law such as a mere proportional relationship. Since the polarizing plate of the present invention is used in a curved surface image display device, controlling the adhesive force against glass in a curved surface state to be within a certain range depends only on the adhesive force against glass in a flat state. Compared with the case of controlling the adhesive force against glass, it leads to the control of the adhesive force of the polarizing plate to the image display element in a state more suitable for actual use. In particular, when the adhesive force against glass (curved surface, 23 ° C.) is 1.5 N / 25 mm or more, and further 2.5 N / 25 mm or more, after the polarizing plate is incorporated in the curved image display panel, it may be used for a long period of time. Even in harsh environments such as when exposed to the heat of the light source due to long-term use or during transportation, which tends to be a hot and humid environment, sufficient adhesive strength to the image display panel can be secured, and the curved image display panel can be used. The polarizing plate is less likely to come off or float from the surface.

From the viewpoint of ensuring sufficient adhesive strength to the image display panel for a long period of time and / or in a high temperature environment, the polarizing plate of the present invention has adhesive strength against glass (flat surface, 23 ° C.) and adhesive strength against glass (curved surface, 23 ° C.). ) Are preferably 2.0 N / 25 mm or more, preferably 3.0 N / 25 mm or more, and particularly preferably 4.0 N / 25 mm or more.

On the other hand, in the manufacturing process of the curved image display panel, if the polarizing plate is bonded to the image display element or if the bonding failure occurs after the polarizing plate is bonded, it is in a flat state as in the conventional flat image display panel manufacturing process. It may be reworked (that is, peeled off and the panel is reused), but it is also assumed that the panel is reworked in a curved state. When reworked in a curved state, in addition to the compressive stress already applied due to the curved state, further compressive stress is applied to peel the polarizing plate from the image display panel. For this reason, the peeling of the polarizing plate from the curved image display panel tends to be technically difficult in the rework in the curved state as compared with the rework in the flat state. In particular, the higher the adhesive strength of the polarizing plate, the more difficult the polarizing plate is peeled. Since the compressive stress applied for this purpose becomes large, problems such as the glass plate constituting the display panel breaking during peeling are likely to occur.

If the adhesive strength to the glass is too high, the polarizing plate cannot be lifted or peeled off from the image display panel, but the above-mentioned reworkability may be a problem. Therefore, the polarizing plate of the present invention may have a problem. The adhesive strength to glass (flat surface, 23 ° C.) measured in a flat state is preferably 20.0 N / 25 mm or less, more preferably 15.0 N / 25 mm or less, still more preferably 10.0 N / 25 mm or less. Particularly preferably, it is 6.0 N / 25 mm or less. The adhesive strength against glass (curved surface, 23 ° C.) is preferably 20.0 N / 25 mm or less, more preferably 15.0 N / 25 mm or less, still more preferably 10.0 N / 25 mm or less, and particularly. It is preferably 6.0 N / 25 mm or less.
When the upper limit of the adhesive force against glass is within the above range, it is easy to easily rework the polarizing plate from the display panel when the polarizing plate is damaged or found in the manufacturing process of the curved image display panel. Become. From the viewpoint of reworkability, in the present invention, it is preferable that both the adhesive force against glass (flat surface, 23 ° C.) and the adhesive force against glass (curved surface, 23 ° C.) are 20.0 N / 25 mm or less.

When the polarizing plate of the present invention contains an adhesive layer, the adhesive force against glass (flat surface, 23 ° C.) is 20.0 N / 25 mm or less, further 15.0 N / 25 mm or less, particularly 10.0 N / 25 mm, particularly 6. Even if it is 0 N / 25 mm or less, especially 4.0 N / 25 mm or less, since the equation (1) is satisfied, floating and peeling can be suppressed.

The adhesive strength to glass (flat surface, 23 ° C.) is such that a polarizing plate cut to a predetermined size is attached to a flat glass substrate via the adhesive layer, autoclaved, and then 23 ° C., 50% RH. This is a value measured by peeling the polarizing plate from the glass substrate in the 180 ° direction at a predetermined speed after allowing it to stand for 24 hours. The adhesive force against glass (curved surface, 23 ° C.) is a metal plate obtained by processing a test piece in which a polarizing plate is attached to a glass plate in the same manner as the method for measuring the adhesive force against glass (flat surface, 23 ° C.) to a radius of curvature of 2500 mm. It is a value measured by peeling off the polarizing plate after allowing the test piece to stand at 23 ° C. and 50% RH for 24 hours in a state where the test piece is fixed along the top.
More detailed measurement methods for the adhesive force against glass (flat surface, 23 ° C.) and the adhesive force against glass (curved surface, 23 ° C.) are as described in Examples described later.

In the polarizing plate of the present invention, it may be described as "adhesive strength against glass (hereinafter," flat surface, 80 ° C.) "of the adhesive layer measured in a flat state after 250 hours under drying at 80 ° C." ) Is preferably 7.0 N / 25 mm or more, more preferably 9.0 N / 25 mm or more, and further preferably 11.0 N / 25 mm or more. Further, in the case where the polarizing plate of the present invention is described as "adhesive strength against glass (hereinafter," curved surface, 80 ° C.) "of the adhesive layer measured in a curved surface state after 250 hours under drying at 80 ° C." Is preferably 8.0 N / 25 mm or more, more preferably 10.0 N / 25 mm or more, and further preferably 12.0 N / 25 mm or more. Further, due to the increased adhesive strength, the test piece may be broken at the time of measurement, and the adhesive strength to each glass measured after 250 hours under drying at 80 ° C. may not be measured as a numerical value. This is the present invention. This is a particularly preferable aspect of.
When the adhesive strength to each glass measured after 250 hours under 80 ° C. dry is the above value, sufficient adhesive strength to the display panel is ensured even when used for a long period of time and / or in a high temperature environment. It is possible to prevent the display panel from peeling off or floating from the curved surface. In the above-mentioned polarizing plate having a certain range of adhesive strength against glass (flat surface, 23 ° C.), it is the above-mentioned value that each adhesive strength against glass measured after 250 hours under drying at 80 ° C. is the above-mentioned value. It is particularly advantageous for polarizing plates.

The adhesive force against glass (flat surface, 80 ° C.) is preferably 5.0 N / 25 mm or more higher than the adhesive force against glass (flat surface, 23 ° C.), more preferably 7.0 N / 25 mm or more, and 10.0 N / It is particularly preferable that the height is 25 mm or more. Further, the adhesive force against glass (curved surface, 80 ° C.) is preferably 5.0 N / 25 mm or more higher than the adhesive force against glass (curved surface, 23 ° C.), and more preferably 7.0 N / 25 mm or more. It is particularly preferable that the height is 0 N / 25 mm or more. In the above-mentioned polarizing plate having a certain range of adhesive strength against glass (flat surface, 23 ° C.), each adhesive strength against glass measured after 250 hours under drying at 80 ° C. was measured at 23 ° C. and 50% RH. If it is 5.0 N / 25 mm or more higher than each glass adhesive force, it is necessary to bond it to the image display element and use it in a normal temperature to low temperature environment in the initial state of bonding after bonding to the image display element. It is possible to easily rework while ensuring a good adhesive strength. Furthermore, it is possible to secure sufficient adhesive force to the display panel even when it is exposed to the heat of a light source for a long time, when it is transported in a hot and humid environment, and when it is used for a long time and / or in a high temperature environment. It is less likely that the state display panel will come off or float.
Difference between glass adhesive strength (flat surface, 80 ° C) and glass adhesive strength (flat surface, 23 ° C), and difference between glass adhesive strength (curved surface, 80 ° C) and glass adhesive strength (curved surface, 23 ° C) The upper limit thereof is not particularly limited, but is usually 20.0 N / 25 mm or less.

The adhesive force against glass (curved surface, 80 ° C.) is preferably 5.0 N / 25 mm or more higher than the adhesive force against glass (flat surface, 23 ° C.), more preferably 7.0 N / 25 mm or more, and 10.0 N / It is particularly preferable that the height is 25 mm or more. When the difference between the adhesive force against glass (curved surface, 80 ° C.) and the adhesive force against glass (flat surface, 23 ° C.) is within the above range, bonding and reworking in a flat state are easy, and a long period of time after the curved surface is formed. And / or even when used in a high temperature environment, sufficient adhesive force to the display panel can be ensured, and peeling or floating from the curved display panel is less likely to occur.

The adhesive strength against glass (flat surface, 80 ° C.) and the adhesive strength against glass (curved surface, 80 ° C.) are as described above, except that the test piece is allowed to stand in a dry environment at 80 ° C. for 250 hours. , 23) and the adhesive strength to glass (curved surface, 23 ° C.) are measured by the same method.

The adhesive strength of the adhesive layer to glass varies depending on the types of components constituting the adhesive layer, their content ratios, formation conditions (drying, active energy ray irradiation conditions), thickness after formation, etc., and therefore desired adhesiveness to glass. The constituent components, the content ratio, the formation conditions, the thickness, and the like of the adhesive layer may be appropriately selected according to the force. Specifically, for example, by using an acrylic resin as a constituent component of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, blending a silane compound, and increasing the layer thickness of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer against glass Can be raised. Further, the adhesive strength to glass can be controlled to a desired value by changing the type and ratio of the monomers constituting the acrylic resin, the type and content of the silane compound.

<Polarizing film>
As the polarizing film that can form the polarizing plate of the present invention, a film having a function of extracting linearly polarized light from incident natural light, for example, a polyvinyl alcohol-based resin film in which a bicolor dye is adsorbed and oriented is used. be able to. 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 (for example, ethylene-vinyl acetate copolymer weight). Coalescence, etc.). Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based 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, polyvinyl acetal, polyvinyl butyral, etc. modified with aldehydes can be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1000 to 10000, preferably 1500 to 5000.

A film formed of such a polyvinyl alcohol-based resin can be used as a raw film for a polarizing film. The method for forming the film of the polyvinyl alcohol-based resin is not particularly limited, and the film can be formed by a conventionally known method. The film thickness of the raw film made of the polyvinyl alcohol-based resin is not particularly limited, but is, for example, 10 to 150 μm, preferably 15 to 100 μm, more preferably, considering the ease of stretching. Is 20 to 80 μm.
is there.

The polarizing film is usually a step of uniaxially stretching a polyvinyl alcohol-based resin film such as a polyvinyl alcohol film, a step of adsorbing a bicolor dye by dyeing the polyvinyl alcohol-based resin film with a bicolor dye, and the like. It is produced through a step of treating a polyvinyl alcohol-based resin film on which a bicolor dye is adsorbed with an aqueous boric acid solution, and a step of washing with water after the treatment with the aqueous boric acid solution. From an industrial point of view, it is preferable to use the stretched / dyed polyvinyl alcohol film produced thereby as a polarizing film. The stretched / dyed polyvinyl alcohol film is a stretched polyvinyl alcohol film containing (adsorbed) a dichroic dye, and the stretching ratio is as follows.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed 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 may be uniaxially stretched using a thermal roll. 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 polarizing film. The draw ratio is usually 4.5 times or more from the viewpoint of expressing the function as a polarizing film.

As a method of dyeing the polyvinyl alcohol-based resin film with the dichroic dye, for example, a method of immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye can be mentioned. As the dichroic dye, for example, iodine or a dichroic dye is used. For dichroic dyes, for example, C.I. I. Included are dichroic direct dyes made of disazo compounds such as DIRECT RED 39, and dichroic direct dyes made of trisazo, tetrakisazo compounds and the like. 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 iodine content 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.

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, 100 parts by mass of water per usually 1 × 10 ^-4 to 10 parts by weight, preferably 1 × 10 ^-3 to 1 parts by weight, more preferably 1 × 10 ^{- 3} to 1 x 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 a boric acid-containing aqueous solution. The amount of boric acid in the boric acid-containing 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 dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing 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-containing 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-containing 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 polarizing film. 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 60 to 600 seconds, preferably 120 to 600 seconds.

As described above, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment to obtain a polarizing film. The thickness of the polarizing film can be, for example, 5 to 40 μm.

Since the coating type thin film polarizing film has a smaller dimensional change rate than the conventionally known polarizing film obtained by stretching a polyvinyl alcohol-based resin film, the coating type thin film polarizing film can be used for a long period of time. / Or the dimensional change of the polarizing plate in use in a high temperature environment can be suppressed. Further, it can contribute to thinning the polarizing plate, which is suitable in the present invention. As the coating type thin film polarizing film, for example, those exemplified in JP2012-58381, JP2013-37115, International Publication No. 2012/147633, and International Publication No. 2014/091921 can be used.

<Protective layer>
In a preferred embodiment, the polarizing plate of the present invention has a protective layer laminated on one or both sides of the polarizing film. The polarizing plate of the present invention preferably has a protective layer because the protective layer contributes to, for example, preventing the polarizing film from shrinking and expanding, and preventing deterioration of the polarizing film due to temperature, humidity, ultraviolet rays, and the like.

As the material for forming the protective layer, a material having excellent transparency, mechanical strength, thermal stability, moisture shielding property, isotropic property and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, and styrene such as polystyrene and acrylonitrile-styrene copolymer (AS resin). Examples thereof include based polymers and polystyrene polymers. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, and sulfone polymers. , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, allylate polymer, polyoxymethylene polymer, epoxy polymer, or the above. Polymer blends and the like are also examples of polymers that form a protective layer. The protective layer can also be formed as a cured layer made of a thermosetting type or ultraviolet curable type resin such as acrylic type, urethane type, acrylic urethane type, epoxy type and silicone type. Among them, those having a hydroxyl group having reactivity with an isocyanate cross-linking agent are preferable, and a cellulosic polymer is particularly preferable. The thickness of the protective layer is not particularly limited, but is generally 500 μm or less, preferably 1 to 300 μm, more preferably 5 to 200 μm, and even more preferably 30 to 100 μm. Further, the protective layer may be made of a transparent protective film or the like to which an optical compensation function is added. The thickness of the outer protective layer laminated on the back surface side of the polarizing film and the thickness of the inner protective layer laminated on the visible side of the polarizing film are the same, or the outer protective layer is more than the inner protective layer. It is preferable to make it thicker. By doing so, curling of the outer and inner protective layers is suppressed, or curls toward a lower rigidity, particularly when heat is applied to the polarizing plate, so that peeling or floating from the display panel is unlikely to occur. This is particularly preferably applied on the concave side.

By increasing the rigidity of the protective layer adjacent to the polarizing film, the shrinkage of the polarizing film can be suppressed, so that the dimensional change of the polarizing plate can be suppressed by controlling the rigidity of the protective layer. Here, the rigidity is the product of the tensile elastic modulus (hereinafter, 23 ° C. elastic modulus) of the film used for the protective layer at room temperature (23 ° C.) multiplied by the film thickness, and the tensile elastic modulus under 80 ° C. (hereinafter, hereinafter). It is defined as the product of (80 ° C. elastic modulus) and the film thickness. In particular, by increasing the rigidity by multiplying the elastic modulus at 80 ° C. by the film thickness, it is possible to suppress the dimensional change of the polarizing plate in a high temperature environment. For example, the cellulose-based polymer represented by triacetyl cellulose preferably has an elastic modulus of 23 ° C. in the range of 3000 to 5000 MPa and the elastic modulus of 80 ° C. in the range of 2000 to 4000 MPa, and the acrylic polymer represented by polymethylmethacrylate. , 23 ° C elastic modulus is preferably in the range of 2000 to 4000 MPa and 80 ° C elastic modulus is in the range of 800 to 2500 MPa, and a polyolefin polymer having a norbornene structure has a 23 ° C elastic modulus of 2000 to 4000 MPa and an 80 ° C elastic modulus. Is preferably in the range of 1500 to 3000 MPa.

The surface of the protective layer that is not adhered to the polarizing film may have a surface treatment layer, for example, even if it has an optical layer such as a hard coat layer, an antireflection layer, a sticking prevention layer, or an antiglare layer or a diffusion layer. Good.

The hard coat layer is intended to prevent scratches on the surface of the polarizing plate. For example, a cured film having excellent hardness and slipperiness due to an ultraviolet curable resin such as acrylic or silicone is added to the surface of the protective layer. It can be formed by a method or the like. The antireflection layer is intended to prevent reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional method. Further, the sticking prevention layer is intended to prevent adhesion to an adjacent layer.

Further, the anti-glare layer is intended to prevent external light from being reflected on the surface of the polarizing plate and hindering the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the protective layer by a method such as a method or a method of blending transparent fine particles. The fine particles contained for forming the surface fine uneven structure include, for example, silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide and the like having an average particle size of 0.5 to 50 μm. Examples thereof include transparent fine particles such as inorganic fine particles that may have conductivity and organic fine particles made of crosslinked or uncrosslinked polymers. When forming the surface fine uneven structure, the content of the fine particles is usually 2 to 50 parts by mass and preferably 5 to 25 parts by mass with respect to 100 parts by mass of the transparent resin forming the surface fine uneven structure. The anti-glare layer may also serve as a diffusion layer (such as a viewing angle enlargement function) for diffusing the light transmitted through the polarizing plate to expand the viewing angle and the like. The protective layer may contain a known additive, if necessary. Additives include ion traps, antioxidants, sensitizers, light stabilizers, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, pigments, antistatic agents, And UV absorbers and the like.

The antireflection layer, antisticking layer, diffusion layer, antiglare layer and the like can be provided on the protective layer itself and integrated, or can be separately provided as an optical layer separately from the protective layer. ..

<Adhesive layer>
The polarizing film and the protective layer are usually bonded via an adhesive. The adhesive for adhering the polarizing film and the protective layer is not particularly limited, but is water-based, that is, an adhesive in which the adhesive component is dissolved in water, from the viewpoint of thinning the formed adhesive layer. , Or an adhesive component dispersed in water. For example, an adhesive containing a polyvinyl alcohol-based resin or a urethane resin can be used as the adhesive component. When the polarizing film has protective layers on both sides, the adhesive used for the adhesion may be the same or different.

When a polyvinyl alcohol-based resin is contained as an adhesive component, the polyvinyl alcohol-based resin includes partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, and methylol group-modified polyvinyl alcohol. , A modified polyvinyl alcohol-based resin such as amino group-modified polyvinyl alcohol may be used. Usually, an adhesive containing a polyvinyl alcohol-based resin as an adhesive component is prepared as an aqueous solution of the polyvinyl alcohol-based resin. The concentration of the polyvinyl alcohol-based resin in the adhesive is usually 1 to 10 parts by mass, preferably 1 to 5 parts by mass with respect to 100 parts by mass of water.

The adhesive containing a polyvinyl alcohol-based resin as an adhesive component preferably contains a curable component such as glioxal or a water-soluble epoxy resin and / or a cross-linking agent in order to improve the adhesiveness. Examples of the water-soluble epoxy resin include a polyamide polyamine epoxy resin obtained by reacting epichlorohydrin with a polyamide amine obtained by reacting a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid. Can be preferably used. Commercially available products of such polyamide polyamine epoxy resin include "Smiley's Resin 650" (manufactured by Sumika Chemtex Co., Ltd.), "Smiley's Resin 675" (manufactured by Sumika Chemtex Co., Ltd.), and "WS-525" (Japan). (Manufactured by PMC Co., Ltd.) and the like. The amount of these curable components and / or cross-linking agents added (the total amount when added together) is usually 1 to 100 parts by mass, preferably 1 to 50 parts by mass with respect to 100 parts by mass of the polyvinyl alcohol-based resin. Is. When the amount of the curable component and / or the cross-linking agent added is within the above range, the adhesiveness is improved and an adhesive layer showing good adhesiveness can be formed.

When a urethane resin is contained as an adhesive component, it is preferable to use a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group. Here, the polyester-based ionomer type urethane resin is a urethane resin having a polyester skeleton, and a small amount of an ionic component (hydrophilic component) is introduced into the skeleton. Such an ionomer type urethane resin is suitable as a water-based adhesive because it is directly emulsified in water to form an emulsion without using an emulsifier. The polyester ionomer type urethane resin itself is known. For example, Japanese Patent Application Laid-Open No. 7-97504 describes as an example of a polymer dispersant for dispersing a phenolic resin in an aqueous medium. In Kai 2005-70140 and JP-A-2005-208456, a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group is used as an adhesive, and a cycloolefin-based polarizing film made of a polyvinyl alcohol-based resin is used as an adhesive. A form in which a resin film is bonded is shown.

The adhesive can be applied to the polarizing film and / or the protective layer (protective film) attached thereto by a known method, for example, casting method, Meyer bar coating method, gravure coating method, comma. A coater method, a doctor blade method, a die coating method, a dip coating method, a spray method and the like can be used. The casting method is a method in which an adhesive is poured down on the surface of a film to be coated while being moved in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two. After applying the adhesive, the polarizing film and the protective layer to be bonded to the polarizing film are laminated, sandwiched by a nip roll or the like, and the film is bonded. The film can be attached using a nip roll, for example, by applying an adhesive and then applying pressure with a roll to spread it evenly. After applying the adhesive, the film is passed between the rolls and pressed. A method of spreading can be adopted. In this case, the material of the roll used may be metal, rubber, or the like. Further, when the film is passed between the plurality of rolls and spread out, the plurality of rolls may be made of the same material or different materials.

The adhesive surface between the polarizing film and the protective layer may be appropriately subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, frame (flame) treatment, and saponification treatment in order to improve the adhesiveness. Examples of the saponification treatment include a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide.

A polarizing plate can be obtained by drying and curing the adhesive after the above bonding. This drying treatment is performed, for example, by blowing hot air, and the temperature thereof is usually in the range of 40 to 100 ° C, preferably in the range of 60 to 100 ° C. The drying time is usually 20 to 1200 seconds.

The thickness of the adhesive layer formed by the adhesive after drying is usually 0.001 to 5 μm, preferably 0.01 to 2 μm, and more preferably 0.01 to 1 μm. When the thickness of the adhesive layer is within the above range, sufficient adhesiveness can be ensured, the appearance is preferable, and the thickness of the polarizing plate can be contributed to the thinning of the polarizing plate, which is suitable for the polarizing plate of the present invention.

After the above drying, curing may be performed at a temperature of room temperature or higher for at least half a day, preferably several days or longer to obtain sufficient adhesive strength. The curing temperature is preferably in the range of 30 to 50 ° C, more preferably in the range of 35 to 45 ° C. When the curing temperature is within the above range, so-called “winding” in the roll-wound state is less likely to occur. The humidity at the time of curing is not particularly limited, and the relative humidity may be in the range of 0 to 70% RH. The curing time is usually 1 to 10 days, preferably 2 to 7 days.

Further, as the adhesive, a photocurable adhesive can also be used. Examples of the photocurable adhesive include a mixture of a photocurable epoxy resin and a photocationic polymerization initiator, and a mixture of a photocurable acrylic resin and a photoradical polymerization initiator. When a photocurable adhesive is used, the photocurable adhesive is cured by irradiating it with active energy rays. The light source of the active energy ray is not particularly limited, but an active energy ray having an emission distribution at a wavelength of 400 nm or less is preferable, and specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, and a black light lamp. , Microwave-excited mercury lamp, metal halide lamp and the like are preferable.

The light irradiation intensity of the photocurable adhesive is appropriately determined by the composition of the photocurable adhesive and is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is preferably 0.1 to 1. It is 6000 mW / cm ² , more preferably 10 to 1000 mW / cm ² , and even more preferably 20 to 500 mW / cm ² . When the irradiation intensity is within the above range, the reaction time can be secured, and the yellowing of the epoxy resin and the deterioration of the polarizing film due to the heat radiated from the light source and the heat generated during the curing of the photocurable adhesive can be suppressed. Can be done. The light irradiation time of the photocurable adhesive may be appropriately selected depending on the photocurable adhesive to be cured, and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time. It is preferably 10 to 10000 mJ / ^{m 2,} more preferably 50~1000mJ / ^{m 2,} more preferably is set to be 80~500mJ / ^{m 2.} When the integrated amount of light to the photocurable adhesive is within the above range, a sufficient amount of active species derived from the polymerization initiator can be generated, the curing reaction can proceed more reliably, and the irradiation time becomes longer. Not too much, and good productivity can be maintained.

When the photocurable adhesive is cured by irradiation with active energy rays, various polarizing plates such as the degree of polarization, transmittance and hue of the polarizing film, and the transparency of various films constituting the protective layer and the optical layer are used. It is preferable to perform curing under conditions that do not deteriorate the function.

<Optical layer>
If necessary, the polarizing plate of the present invention may be further laminated with optical layers such as a retardation film, a viewing angle compensation film, and a brightness improving film.

Examples of the retardation film include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an alignment film of a liquid crystal polymer, and a film in which an alignment layer of a liquid crystal polymer is supported by a film. The stretching treatment can be performed by, for example, a roll stretching method, a long gap line stretching method, a tenter stretching method, a tubular stretching method, or the like. The draw ratio is generally 1.1 to 3 times in the case of uniaxial stretching. The thickness of the retardation film is not particularly limited, but is usually 10 to 200 μm, preferably 20 to 100 μm.

Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, and the like. Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyvinyl alcohol, polyamide, polyimide, polyolefin, polyolefin having norbornene structure, polyvinyl chloride, cellulose-based polymer, or binary and ternary various copolymers and grafts thereof. Examples thereof include copolymers and blends. These polymer materials become oriented substances (stretched films) by stretching or the like.

Examples of the liquid crystal polymer include various main chain type and side chain type polymers in which a conjugated linear atomic group (mesogen) that imparts liquid crystal orientation is introduced into the main chain or side chain of the polymer. Specific examples of the main chain type liquid crystal polymer include a nematically oriented polyester liquid crystal polymer, a discotic polymer, a cholesteric polymer, and the like having a structure in which a mesogen group is bonded at a spacer portion that imparts flexibility. Specific examples of the side chain type liquid crystal polymer include polysiloxane, polyacrylate, polymethacrylate or polymalonate as the main chain skeleton, and para-substitution with nematic orientation imparting via a spacer portion composed of conjugated atomic groups as the side chain. Examples thereof include those having a mesogen portion composed of a cyclic compound unit. For these liquid crystal polymers, for example, a solution of the liquid crystal polymer is developed on an orientation-treated surface such as a thin film formed on a glass plate, such as polyimide or polyvinyl alcohol, which is rubbed, or silicon oxide is obliquely vapor-deposited. It is carried out by heat treatment.

The retardation film may have a retardation according to the purpose of use, such as a film for the purpose of compensating for coloring or viewing angle due to birefringence of various wave plates or liquid crystal layers, and may have two or more types of retardation. Films may be laminated to control optical characteristics such as phase difference.

The viewing angle compensation film is a film for widening the viewing angle so that the image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a direction slightly oblique to the screen. Examples of such a viewing angle compensating film include a retardation film, an alignment film such as a liquid crystal polymer, and a film in which an alignment layer such as a liquid crystal polymer is supported on a transparent base material. A normal retardation film uses a polymer film having birefringence stretched uniaxially in the plane direction, whereas a retardation film used as a viewing angle compensation film has birefringence stretched in the plane direction. A polymer film having refraction, a polymer having birefringence with controlled refractive index in the thickness direction, which is uniaxially stretched in the plane direction and also stretched in the thickness direction, and a bidirectionally stretched film such as a tilt-oriented film are used. .. Examples of the tilt-aligned film include a film in which a heat-shrinkable film is adhered to a polymer film and the polymer film is stretched or / or shrunk under the action of the shrinkage force due to heating, or a liquid crystal polymer is obliquely oriented. Can be mentioned. As the raw material polymer of the retardation film, the same polymer as that described in the above retardation film is used to prevent coloring due to a change in viewing angle based on the phase difference due to the liquid crystal cell and to prevent coloring and the like for good visibility. Those for the purpose of enlargement or the like can be appropriately selected and used.

Further, from the viewpoint of achieving a wide viewing angle with good visibility, a viewing angle compensating film in which an optically anisotropic layer composed of an oriented layer of a liquid crystal polymer, particularly a tilted oriented layer of a discotic liquid crystal polymer, is supported by a triacetyl cellulose film is used. It is preferably used.

A polarizing plate in which a polarizing plate and a brightness improving film are bonded is usually provided on the back side of a liquid crystal cell and used. The brightness-enhancing film reflects the linearly polarized light of the predetermined polarizing axis or the circularly polarized light in the predetermined direction when natural light is incident due to the backlight of a liquid crystal display device or the reflection from the back side, and exhibits the property of transmitting other light. In the polarizing plate in which the brightness improving film is laminated with the polarizing plate, light from a light source such as a backlight is incident to obtain transmitted light in a predetermined polarized state, and light other than the predetermined polarized state is reflected without being transmitted. To. The light reflected on the surface of the luminance improving film is further inverted via a reflective layer or the like provided behind the surface of the luminance improving film to be re-incidented on the luminance improving film, and a part or all of the light is transmitted as light in a predetermined polarized state to provide brightness. It is possible to improve the brightness by increasing the amount of light transmitted through the improving film and supplying polarized light that is difficult to be absorbed by the polarizing film to increase the amount of light that can be used for displaying a liquid crystal image or the like. That is, when light is incident through the polarizing film from the back side of the liquid crystal cell with a backlight or the like without using the brightness improving film, the light having a polarization direction that does not match the polarization axis of the polarizing film is almost polarized. It is absorbed by the film and does not pass through the polarizing film. That is, although it depends on the characteristics of the polarizing film used, about 50% of the light is absorbed by the polarizing film, and the amount of light that can be used for displaying a liquid crystal image or the like is reduced by that amount, and the image becomes dark. In the brightness improving film, light having a polarization direction that is absorbed by the polarizing film is not incident on the polarizing film, but is once reflected by the brightness improving film and then inverted via a reflective layer or the like provided behind the polarizing film. It is repeatedly made to re-enter the brightness improving film, and only the polarized light whose polarization direction is such that the polarization direction of the light reflected and inverted between the two can pass through the polarizing film is transmitted to the polarizing film. Since it is supplied, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

The polarizing plate of the present invention can be manufactured, for example, by attaching a protective layer to a polarizing film with an adhesive and forming an adhesive layer on the surface of the protective layer on the side to be attached to the image display element. When the polarizing plate of the present invention further contains an optical layer, for example, various films constituting the optical layer are bonded to the protective layer with an adhesive to form an adhesive layer on the surface opposite to the surface adhered to the protective layer. Just do it. The polarizing plate of the present invention can be obtained by forming a polarizing plate obtained by laminating each film and layer constituting the polarizing plate into a curved surface so as to have a desired radius of curvature before bonding with the image display element. it can. Further, the curved surface can be formed after being bonded to the image display element.

Regarding bonding with an image display element, for example, when used for a curved liquid crystal display panel, the polarizing plate of the present invention may be bonded to a liquid crystal cell which is an image display element via an adhesive layer. When used for a curved organic EL panel, the polarizing plate of the present invention may be attached to the viewing side display surface of the organic EL display element, which is an image display element, via an adhesive layer.

For example, in the case of a liquid crystal display panel, the curved surface of the polarizing plate is fixed to the frame in a state where the laminated body of the image display element produced as described above and the concave-side and convex-side polarizing plates is bent by a predetermined radius of curvature. However, it can be carried out by a method of placing the laminate on the backlight unit or a method of placing the laminate on the backlight unit curved with a predetermined radius of curvature and pressing the laminated body from above with a frame.

The polarizing plate of the present invention can be used as a polarizing plate of a curved image display panel such as a curved liquid crystal panel or a curved organic EL panel, particularly as a polarizing plate of a curved liquid crystal display panel. In the curved image display panel, compressive stress is always generated due to the curvature of the image display panel. Since the compressive stress is larger on the concave side (visual side), the polarizing plate located on the concave side is likely to change in size, while the image display element to which the polarizing plate is attached is generally sandwiched between glass substrates. Therefore, it is considered that the dimensional change is unlikely to occur, and a difference in shrinkage rate is likely to occur between the concave-side polarizing plate and the image display element. For this reason, peeling or floating of the polarizing plate is particularly likely to occur on the concave side of the curved image display panel. The polarizing plate of the present invention can be used as either a concave-side polarizing plate or a convex-side polarizing plate constituting a curved image display panel, but it has a high suppressing effect on peeling and floating in a curved surface state. In particular, it is suitable as a concave-side polarizing plate incorporated in the concave side of an image display panel. That is, in one embodiment of the present invention, there is provided a curved image display panel including a concave-side polarizing plate and a convex-side polarizing plate, wherein the concave-side polarizing plate is the polarizing plate of the present invention. .. Further, in another embodiment of the present invention, a curved image display panel including a concave-side polarizing plate and a convex-side polarizing plate, wherein the concave-side polarizing plate and the convex-side polarizing plate are the polarizing plates of the present invention. A display panel is provided.

When the polarizing plate of the present invention is used in a liquid crystal display panel, the convex-side polarizing plate and the concave-side polarizing plate are arranged so that the absorption axis directions (stretching directions) of the polarizing films contained in these polarizing plates are orthogonal to each other. Be placed. For example, as shown in FIG. 4, when the absorption axis direction of the polarizing film included in the concave polarizing plate is the horizontal direction, the absorption axis direction of the polarizing film included in the convex polarizing plate is the vertical direction. Further, as shown in FIG. 5, when the absorption axis direction of the polarizing film included in the concave polarizing plate is the vertical direction, the absorption axis direction of the polarizing film included in the convex polarizing plate is the horizontal direction. The absorption axis direction of the polarizing film included in the concave polarizing plate may be a vertical direction, a horizontal direction, or an angle direction of 45 ° with respect to the horizontal direction. In many image display panel products, the absorption axis direction of the polarizing film contained in the concave polarizing plate is the horizontal direction. Especially in this case, deformation such as shrinkage of the polarizing plate is likely to occur, and the polarizing plate is peeled off or lifted. It has been found in the present invention that According to the polarizing plate of the present invention, scratches on the surface of the polarizing plate can be suppressed even when the direction of the absorption axis is horizontal, and the above-mentioned problems can be solved.

Further, the polarizing plate of the present invention can be suitably used for a curved image display panel having various screen sizes. For example, 5 inches (horizontal length: 100 to 150 mm), 10 inches (horizontal length: 200 to 250 mm), 17 inches (horizontal length: 320 to 400 mm), 32 inches (horizontal length: 680). ~ 720 mm), 40 inches (horizontal length: 860-910 mm), 46 inches (horizontal length: 980-1030 mm), 55 inches (horizontal length: 1180 to 1230 mm), 65 inches (horizontal length) : 1400 to 1450 mm), 75 inches (horizontal length: 1600 to 1700 mm), 85 inches (horizontal length: 1800 to 1900 mm) can be used for curved image display panels. The larger the screen size, the larger the size of each component, compressive stress acts on the concave polarizing plate in the curved surface state, and the dimensional mismatch between the polarizing plate and the image display element causes the polarizing plate to peel off. Floating is especially likely to occur. Further, in an image display device having a screen aspect ratio (vertical length: horizontal length) of 3: 4, the polarizing plate is unlikely to peel off or float, but the screen aspect ratio is 9: 13 to 9. : 23, preferably 9:15 or more, more preferably 9:19 or less, for example, in a horizontally long image display panel of 9:16 or 9:21, compressive stress acts on the concave polarizing plate at the time of curved surface. At the same time, the present inventors have also found that the polarizing plate is particularly liable to peel off or float due to the dimensional mismatch between the polarizing plate and the image display element. Since the polarizing plate of the present invention has a high suppressing effect on peeling and floating in a curved surface state, it can be used as a polarizing plate for various screen sizes as described above, particularly a relatively large screen size and a horizontally long curved image display panel. It can be preferably used.

The curved image display panel of the present invention including the polarizing plate of the present invention is excellent in the effect of suppressing peeling and floating of the polarizing plate from the image display panel for a long period of time and / or in a high temperature environment.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

1. 1. Preparation of polarizing film A polyvinyl alcohol film with an average degree of polymerization of about 2,400 and a saponification degree of 99.9 mol% or more and a thickness of 60 μm (trade name “VF-PE # 6000” manufactured by Kuraray Co., Ltd.) at 30 ° C. After immersing in pure water, it was immersed in an aqueous solution having a mass ratio of iodine / potassium iodide / water of 0.02 / 2/100 at 30 ° C. Then, it was immersed in an aqueous solution having a mass ratio of potassium iodide / boric acid / water of 12/5/100 at 56.5 ° C. Subsequently, the film was washed with pure water at 8 ° C. and then dried at 80 ° C. to obtain a polarizing film in which iodine was adsorbed and oriented on the polyvinyl alcohol film. Stretching was mainly performed during iodine staining and boric acid treatment, and the total stretching ratio was 6.0 times. The thickness of the polarizing film thus obtained was 22 μm.

2. 2. Preparation / Preparation of Protective Layer (Protective Film) Various protective layers (protective films) were prepared or prepared as follows.

(1) Acrylic resin film (2-A)
While mixing 70% by mass of methacrylic resin and 30% by mass of rubber particles with a super mixer, 2% by mass of a benzotriazole-based ultraviolet absorber is added to 100% by mass of the mixture, and melt-kneaded with a twin-screw extruder. It was made into pellets. These pellets are put into a 65 mmφ uniaxial extruder, extruded through a T-type die having a set temperature of 275 ° C., cooled by sandwiching the film between two mirror-finished polishing rolls, and cooled to an acrylic resin film having a thickness of 80 μm. 2-A) was obtained.

As the methacrylic resin, a copolymer of methyl methacrylate / methyl acrylate = 96% / 4% (mass ratio) was used. Further, as the rubber particles, the innermost layer is composed of a hard polymer polymerized with methyl methacrylate and a small amount of allyl methacrylate, and the intermediate layer is mainly composed of butyl acrylate, and further styrene and a small amount of methacrylic acid. It is composed of a soft elastic body polymerized with allyl, and the outermost layer is a three-layer structure elastic body particle composed of a hard polymer polymerized with methyl methacrylate and a small amount of ethyl acrylate, and is intermediate. A layer having an average particle size of 240 nm up to the elastic body was used. In the rubber particles, the total mass of the innermost layer and the intermediate layer was 70% of the total particles.

(2) Acrylic resin film (2-B) having a hard coat layer
A hard coat treatment was performed on the above acrylic resin film (2-A). The hard coat treatment is performed on the treatment solution (pentaerythritol triacrylate: 42.5 parts by mass, irgacure 184: 0.25 parts by mass, silicone (leveling agent): 0.1 parts by mass, silica (average particle size 1 μm): 12 parts by mass. Part, surface methacryloyl group-modified silica (surface organic component: 4.05 × 10 ^-3 g / m ² ): 7.5 parts by mass, toluene: 34 parts by mass) is applied, dried, and then used with an ultraviolet irradiator. This was done by irradiating with ultraviolet rays. In this way, an acrylic resin film (2-B) having a hard coat layer having a thickness of 5 μm (overall thickness: 85 μm) was obtained.

(3) TAC film (2-C)
A triacetyl cellulose film "KC6UAW" (thickness: 60 μm) manufactured by Konica Minolta Opto Co., Ltd. was used as a TAC film (2-C).

(4) TAC film (2-D)
A hard coat treatment was performed on the (2-C) TAC film in the same manner as in (2-B). In this way, a TAC film (2-D) having a hard coat layer having a thickness of 5 μm (overall thickness: 65 μm) was obtained.

(5) COP film (2-E)
The cyclic polyolefin-based biaxially stretched resin film "Zeonoa Film ZB12" (thickness 52 μm) of Nippon Zeon Corporation was used as the COP film (2-E).

3. 3. Preparation of Adhesive A solvent-free UV-curable adhesive obtained by mixing the following ingredients was used as the adhesive. In addition,% shows the content (mass%) when the whole adhesive is 100% by mass.
3.4-Epoxy Cyclohexene Methyl-3', 4'-Epoxy Cyclohexene Carboxylate ("Ceroxide 2021P" manufactured by Daicel Chemical Industries, Ltd.): 80%
-1,4-Butanediol diglycidyl ether: 19%
-Photocationic polymerization initiator containing triarylsulfonium hexafluorophosphate as a main component (CPI-100P: propylene carbonate solution containing 50% active ingredient containing triarylsulfonium hexafluorophosphate as a main component, "CPI" manufactured by San-Apro Co., Ltd. -100P "): 1%

4. Preparation of adhesive agent 81.8 parts by mass of ethyl acetate, 70.8 parts by mass of butyl acrylate, 20.0 parts by mass of methyl acrylate, acrylic acid in a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer. Add 8.0 parts by mass of 2-phenoxyethyl, 1.0 part by mass of 2-hydroxyethyl acrylate and 0.6 parts by mass of acrylic acid, and replace the air in the device with nitrogen gas to make it oxygen-free. The temperature was raised to 55 ° C. Then, a total amount of a solution prepared by dissolving 0.14 parts by mass of azobisisobutyronitrile as a polymerization initiator in 10 parts by mass of ethyl acetate was added. This temperature was maintained for 1 hour after the addition of the polymerization initiator, and then ethyl acetate was continuously added into the reaction vessel at an addition rate of 17.3 parts by mass / hour while maintaining the internal temperature at 54 to 56 ° C. to acrylic. The addition of ethyl acetate was stopped when the resin concentration reached 35% by mass. Further, the temperature was kept at this temperature until 12 hours had passed from the start of addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the acrylic resin to 20% by mass. This was used as an acrylic resin.

The weight average molecular weight and the number average molecular weight of the obtained acrylic resin were measured according to the following methods. For the GPC device, 4 columns "TSKgel XL" manufactured by Toso Co., Ltd. and 1 "Shodex GPC KF-802" manufactured by Showa Denko Co., Ltd. and sold by Shoko Co., Ltd., for a total of 5 The books were arranged in series and measured using tetrahydrofuran as an eluent under the conditions of a sample concentration of 5 mg / mL, a sample introduction amount of 100 μL, a temperature of 40 ° C., and a flow velocity of 1 mL / min, in terms of standard polystyrene. The weight average molecular weight Mw of the obtained acrylic resin was 1.42 million, and Mw / Mn was 4.1.

0.5 parts by mass of glycidoxypropyltrimethoxysilane (liquid) as a silane compound with respect to 100 parts by mass of the solid content of the acrylic resin (20% by mass ethyl acetate solution) prepared above (Shinetsu Chemical Industry Co., Ltd. KBM-403), 0.6 parts by mass of coronate HXR (isocyanurate compound of hexamethylene diisocyanate, liquid with approximately 100% by mass of active ingredient, manufactured by Nippon Polyurethane Co., Ltd.), and 3.0 parts by mass as a cross-linking agent. N-octyl-4-methylpyridinium hexafluorophosphate was mixed. Then, ethyl acetate was added so that the solid content concentration became 13% by mass to obtain a pressure-sensitive adhesive.

Example 1
The protective layer film (2-D) and film (2-E) are preliminarily corona-treated using a corona processing machine (manufactured by Kasuga Electric Co., Ltd.), and an adhesive is applied thereto to form a polarizing film. I stuck them together. Then, the adhesive was cured by irradiating ultraviolet rays with a metal halide lamp. A 20 μm pressure-sensitive adhesive layer was formed on the surface of the film (2-E) to obtain a concave-side polarizing plate A having a thickness of 0.17 mm (excluding the separator film used for forming the pressure-sensitive adhesive layer).

Further, in the same manner as above, except that the film (2-C) was used instead of the film (2-D), the convex side polarizing plate having a thickness of 0.16 mm (excluding the separator film used for forming the adhesive layer). I got B.

The polarizing plate A was cut into a size of 1215 mm in the horizontal direction (length in the horizontal direction) × 683 mm in the vertical direction (length in the vertical direction), and at this time, the polarizing plate A was cut so that the absorption axis direction of the polarizing plate A was in the horizontal direction. Further, the polarizing plate B was cut into a size of 1215 mm in width × 683 mm in length, and at this time, the polarizing plate B was cut so that the absorption axis direction was the vertical direction. The cut polarizing plate A is attached to the visible side (concave surface side) of a glass panel having a width of 1215 mm × length of 683 mm and a thickness of 1.5 mm, and the cut polarizing plate B is attached to the back surface side (convex surface side) of this panel. ). Then, the glass panel was bent and fixed so that the average radius of curvature was 4000 mm, and the glass panel was held at 80 ° C. for 250 hours. After 250 hours, the appearance of the panel was visually observed, and no peeling or floating of the polarizing plate occurred. The dimensional change rate measured by the above method was 0.8%. At this time, L1 (H + H1) / 2R = 0.25.

Example 2
The protective layer film (2-B) and film (2-E) are preliminarily corona-treated using a corona processing machine (manufactured by Kasuga Electric Co., Ltd.), and an adhesive is applied thereto to obtain a polarizing film. It was pasted on. Then, the adhesive was cured by irradiating ultraviolet rays with a metal halide lamp. A 20 μm pressure-sensitive adhesive layer was formed on the surface of the film (2-E) to obtain a concave-side polarizing plate C having a thickness of 0.19 mm (excluding the separator film used for forming the pressure-sensitive adhesive layer).

Further, a convex-side polarizing plate D having a thickness of 0.18 mm was obtained in the same manner as described above except that the film (2-A) was used instead of the film (2-B).

The polarizing plate C was cut into a size of 1215 mm in width × 683 mm in length, and at this time, the polarizing plate C was cut so that the absorption axis direction of the polarizing plate C was the lateral direction. Further, the polarizing plate D was cut into a size of 1215 mm in width × 683 mm in length, and at this time, the polarizing plate D was cut so that the absorption axis direction of the polarizing plate D was the vertical direction. The cut polarizing plate C is attached to the visible side (concave side) of a glass panel having a width of 1215 mm × length of 683 mm and a thickness of 1.5 mm, and the cut polarizing plate D is attached to the back side (convex side) of this panel. ). Then, the panel was bent and fixed so that the average radius of curvature was 4000 mm, and the panel was held at 80 ° C. for 250 hours under dry conditions. After 250 hours, the appearance of the panel was visually observed, and no peeling or floating of the polarizing plate occurred. The dimensional change rate measured by the above method was 1.4%. At this time, L1 (H + H1) / 2R = 0.26.

Example 3
The size of the polarizing plates C and D was cut into a size of 1440 mm in width × 810 mm in length, and the polarizing plates C and D were bonded to a glass panel having a thickness of 1440 mm in width × 810 mm in length and 1.5 mm in thickness, and the average radius of curvature was increased. The peeling and floating of the polarizing plate on the curved panel were evaluated in the same manner as in Example 2 except that the panel was bent and fixed so as to have a diameter of 6600 mm. As a result, no large peeling or floating of the polarizing plate occurred. The dimensional change rate measured by the above method was 1.4%. At this time, L1 (H + H1) / 2R = 0.18.

Comparative Example 1
Peeling and floating of the polarizing plate on the curved panel were evaluated in the same manner as in Example 2 except that the average radius of curvature of the panel was 2500 mm. As a result, on the short side of the concave polarizing plate C, floating was generated from the glass up to 50 mm from the side end. The dimensional change rate measured by the above method was 1.4%. At this time, L1 (H + H1) / 2R = 0.41.

Example 4
Except for cutting the size of the polarizing plates C and D to a size of 1440 mm in width × 810 mm in length, and bonding the polarizing plates C and D to a glass panel having a thickness of 1440 mm in width × 810 mm in length and 1.5 mm in thickness. When the peeling and floating of the polarizing plate on the curved panel are evaluated in the same manner as in Example 2, L1 (H + H1) / 2R = 0.30, and the occurrence of large peeling and floating of the polarizing plate is suppressed.

Example 5
Except for cutting the size of the polarizing plates C and D to a size of 1660 mm in width × 934 mm in length, and bonding the polarizing plates C and D to a glass panel having a thickness of 1660 mm in width × 934 mm in length and 1.5 mm in thickness. When the peeling and floating of the polarizing plate on the curved panel are evaluated in the same manner as in Example 2, L1 (H + H1) / 2R = 0.35, and the occurrence of large peeling and floating of the polarizing plate is suppressed.

Example 6
Cutting the size of the polarizing plates C and D to a size of 900 mm in width × 506 mm in length, bonding the polarizing plates C and D to a glass panel having a thickness of 900 mm in width × 506 mm in length and a thickness of 1.5 mm, and When the peeling and floating of the polarizing plate on the curved panel were evaluated in the same manner as in Example 2 except that the average radius of curvature was 2500 mm, L1 (H + H1) / 2R = 0.30, which was found in the polarizing plate. The occurrence of large peeling and floating is suppressed.

Example 7
Cutting the size of the polarizing plates C and D into a size of 508 mm in width × 286 mm in length, bonding the polarizing plates C and D to a glass panel having a thickness of 508 mm in width × 286 mm in length and a thickness of 1.5 mm, and When the peeling and floating of the polarizing plate on the curved panel were evaluated in the same manner as in Example 2 except that the average radius of curvature was 2500 mm, L1 (H + H1) / 2R = 0.17, which was found in the polarizing plate. The occurrence of large peeling and floating is suppressed.

Comparative Example 2
When the peeling and floating of the polarizing plate on the curved panel were evaluated in the same manner as in Example 4 except that the average radius of curvature of the panel was 2500 mm, L1 (H + H1) / 2R = 0.49, and the polarizing plate was obtained. Peeling and floating occur.

Comparative Example 3
When the peeling and floating of the polarizing plate on the curved panel were evaluated in the same manner as in Example 5 except that the average radius of curvature of the panel was 2500 mm, L1 (H + H1) / 2R = 0.56, and the polarizing plate was obtained. Peeling and floating occur.

Comparative Example 4
When the peeling and floating of the polarizing plate on the curved panel were evaluated in the same manner as in Example 6 except that the average radius of curvature of the panel was 1000 mm, L1 (H + H1) / 2R = 0.76, and the polarizing plate was obtained. Peeling and floating occur.

Comparative Example 5
When the peeling and floating of the polarizing plate on the curved panel were evaluated in the same manner as in Example 7 except that the average radius of curvature of the panel was 1000 mm, L1 (H + H1) / 2R = 0.43, and the polarizing plate was obtained. Peeling and floating occur.

Example 8
The size of the polarizing plates A and B was cut into a size of 1050 mm in width × 600 mm in length, and the polarizing plates A and B were bonded to a glass panel having a thickness of 1050 mm in width × 600 mm in length and 1.5 mm in thickness, and the average radius of curvature was increased. The peeling and floating of the polarizing plate on the curved panel were evaluated in the same manner as in Example 1 except that the panel was bent and fixed so as to have a diameter of 2500 mm. As a result, no large peeling or floating of the polarizing plate occurred. The dimensional change rate measured by the above method was 0.8%. At this time, L1 (H + H1) / 2R = 0.35.

5. Evaluation of adhesive strength against glass (1) Measurement of adhesive strength against glass (a) Measurement of adhesive strength against glass (flat surface, 23 ° C) and adhesive strength against glass (curved surface, 23 ° C) Example 1 and Implementation After each set of the test pieces for measuring the adhesive strength against glass in the flat state and the curved state prepared in Example 2 was autoclaved at 50 ° C. and 5 kg / cm ² (490.3 kPa, gauge pressure) for 20 minutes. The glass panel and the polarizing plate were chucked using an autograph (AGS-50NX) manufactured by Shimadzu Corporation after standing for 24 hours in an environment of 23 ° C. and 50% RH, and 180 ° at a speed of 300 mm / min. The polarizing plate was peeled off in the direction of. The peel strength measured thereby was defined as "adhesive strength against glass (flat surface, 23 ° C.)" and "adhesive strength against glass (curved surface, 23 ° C.)". The results are shown in Table 1.

(B) Measurement of "adhesive strength against glass (flat surface, 80 ° C.)" and "adhesive force against glass (curved surface, 80 ° C.)" Adhesive strength against glass in the flat and curved states produced in Examples 1 and 2. Each of the other sets of test pieces for measurement was autoclaved at 50 ° C., 5 kg / cm ² (490.3 kPa, gauge pressure) for 20 minutes, and then allowed to stand at 23 ° C. for 24 hours in a 50% RH environment. After that, it was allowed to stand in a dry environment at 80 ° C. for 250 hours, and the glass panel and the polarizing plate were chucked using an autograph (AGS-50NX) manufactured by Shimadzu Corporation, and 180 at a speed of 300 mm / min. The polarizing plate was peeled off in the direction of °. The peel strength measured thereby was defined as "adhesive strength against glass (flat surface, 80 ° C.)" and "adhesive strength against glass (curved surface, 80 ° C.)". The results are shown in Table 1.

1: Concave side polarizing plate 2: Convex side polarizing plate 3: Image display element 10: Adhesive layer 11: Protective layer 12: Polarizing film 13: Surface treatment layer

Claims (8)

A polarizing plate having a horizontal length of L1 (mm) in a flat state, which is attached to a curved image display panel having an average radius of curvature R (mm) and a thickness H (mm) via an adhesive layer .
The polarizing plate thickness H1 (mm) on the concave side when attached to the curved image display panel is the following formula (1):
L1 (H + H1) / 2R ≦ 0.4 (1)
Meet the,
The horizontal length L1 of the polarizing plate in the flat state is 500 mm or more.
The adhesive force against glass measured in a flat state at 23 ° C. and 50% RH of the adhesive layer is 1.0 N / 25 mm or more.
The dimensional change rate after 250 hours under drying at 80 ° C. is 3.0% or less.
Polarizer. The polarizing plate according to claim 1, wherein the adhesive force against glass is 2.0 N / 25 mm or more. The polarizing plate according to claim 1 or 2, wherein the adhesive layer has an adhesive force against glass of 1.5 N / 25 mm or more measured in a curved surface state at 23 ° C. and 50% RH. The polarizing plate according to any one of claims 1 to 3 , wherein the thickness H of the curved image display panel is 0.4 mm or more. The polarizing plate according to any one of claims 1 to 4 , wherein the polarizing film in the polarizing plate is a stretched / dyed polyvinyl alcohol film. The polarizing plate according to any one of claims 1 to 5 , wherein the curved image display panel has an average radius of curvature R of 900 to 7000 mm. A curved image display panel comprising a concave-side polarizing plate and a convex-side polarizing plate, wherein the concave-side polarizing plate is the polarizing plate according to any one of claims 1 to 6 . A curved image display panel including a concave-side polarizing plate and a convex-side polarizing plate, wherein the concave-side polarizing plate and the convex-side polarizing plate are the polarizing plates according to any one of claims 1 to 6 .