TW201804182A - Polarizing plate set - Google Patents

Abstract

The present invention provides a polarizing plate set with a small warp amount when placed in a moisture/ heat resistant environment and capable of reducing display unevenness caused by possible warpage. The polarizing plate set comprises a back side polarizing plate to be arranged on one side of a liquid crystal cell and a front side polarizing plate to be arranged on the other side of the liquid crystal cell, wherein the back side polarizing plate has a reflective polarizing plate, a first pressure sensitive adhesive layer, a first polarizer, a first protective film, and a second pressure sensitive adhesive layer; the front polarizing plate has a third pressure sensitive adhesive layer, a second polarizer, and a second protective film; in the case that the difference dF-dR obtained by subtracting the thickness dR ([mu]m) of the first polarizer in the back side polarizing plate from the thickness dF ([mu]m) of the second polarizer in the front side polarizing plate is set to [Delta] d ([mu]m), 0 [mu]m < [Delta] d < 5 [mu]m; and the angle formed by the absorption axis of the second polarizer in the front side polarizing plate and the absorption axis of the first polarizer in the back side polarizing plate is 90 DEG ± 1 DEG.

Description

Polarizer set

This invention relates to polarizer sets that can be used in a variety of optical applications.

The polarizer is disposed on both sides of the liquid crystal cell due to the image forming method of the liquid crystal display device.

For example, Patent Document 1 discloses a liquid crystal panel in which a polarizer is disposed on a front side and a back side of a liquid crystal cell. Further, Patent Document 2 discloses an optical layered body disposed on the front side and the back side of the liquid crystal cell.

According to the liquid crystal panel disclosed in Patent Document 1 and the optical laminate disclosed in Patent Document 2, it is attempted to reduce the liquid crystal panel by defining the relationship between the thickness of the polarizing film disposed on the front side and the thickness of the polarizing film disposed on the back side. Warp.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2012-58429

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2013-37115

In the past, attention has been paid only to warpage in a high-temperature environment, and as long as the warpage is suppressed, it is considered that there is no problem of warpage of the liquid crystal panel, but the thickness of the liquid crystal cell becomes thin (for example, the thickness of the glass substrate constituting the liquid crystal cell is (0.5 mm or less), it is understood that the warpage of the liquid crystal cell is remarkably confirmed due to the stress of the polarizing plate generated by a slight dimensional change amount in a hot and humid environment (for example, 60 ° C and a humidity of 90%).

According to the inventions disclosed in Patent Documents 1 and 2, depending on conditions such as the structure of the protective film and the polarizing plate to be used, the liquid crystal panel is peeled off from the touch panel and the backlight unit is detached due to warpage of the liquid crystal panel in a hot and humid environment. problem.

Accordingly, an object of the present invention is to provide a polarizing plate set which is capable of suppressing warpage of a liquid crystal panel in a high temperature environment and suppressing warpage of a liquid crystal panel in a hot and humid environment.

The invention includes the following.

[1] A polarizing plate kit comprising: a back side polarizing plate disposed on one surface side of the liquid crystal cell; and a front side polarizing plate disposed on the other surface side; wherein the back side polarizing plate includes a reflective polarizing plate 1) an adhesive layer, a first polarizer, a first protective film, and a second adhesive layer; the front polarizing plate includes a third adhesive layer, a second polarizer, and a second protective film; and the front side polarized light When the thickness dF ( μm ) of the second polarizer of the plate is smaller than the thickness dR ( μm ) of the first polarizer of the back side polarizing plate, and the difference dF-dR is Δd ( μm ), 0 μ m < Δd < 5 μ m; the angle between the absorption axis of the second polarizer of the front side polarizing plate and the absorption axis of the first polarizer of the back side polarizing plate is 90° ± 1°.

[2] The polarizing plate kit according to [1], wherein an angle between an absorption axis of the first polarizer of the back side polarizing plate and a long side of the back side polarizing plate is 0°±0.5°.

[3] The polarizing plate kit according to [1], wherein the reflective polarizing plate has at least two thin films, and the refractive index anisotropy of the at least two thin films is different.

[4] A liquid crystal panel comprising a liquid crystal cell and a pair of polarizing plates disposed on both surfaces of the liquid crystal cell, wherein the pair of polarizing plates are the polarizing plate set according to any one of [1] to [3] The liquid crystal panel is sequentially provided with a second protective film, a second polarizer, a third adhesive layer, a liquid crystal cell, a second adhesive layer, a first protective film, a first polarizer, and a first adhesive layer. Reflective polarizer.

According to the present invention, a polarizing plate set can be obtained which can reduce the warpage of the liquid crystal panel when exposed to a hot and humid environment and a high temperature environment.

10‧‧‧Back side polarizer

10a‧‧‧Absorption axis of the first polarizer of the back side polarizer

10b‧‧‧ penetration axis of the first polarizer

10c‧‧‧Long side of the back side polarizer

11‧‧‧Reflective polarizer

12‧‧‧1st adhesive layer

13‧‧‧1st polarizer

14‧‧‧1st protective film

15‧‧‧2nd adhesive layer

20‧‧‧ Front side polarizer

20a‧‧‧Absorption axis of the second polarizer of the front side polarizer

20b‧‧‧ penetration axis of the 2nd polarizer

21‧‧‧3rd adhesive layer

22‧‧‧2nd polarizer

23‧‧‧2nd protective film

30‧‧‧Liquid Crystal Unit

40‧‧‧Measurement point

50‧‧‧Polar plate

60‧‧‧ glass plate

dF, dR‧‧‧ thickness

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing an aspect of a polarizing plate set of the present invention.

Fig. 2 is a view showing the absorption axis and the back side polarizing plate of the front side polarizing plate Schematic diagram of the angle formed by the absorption axis.

Fig. 3 is a view showing the measurement of the amount of warpage.

Hereinafter, the polarizing plate set of the present invention will be described using an appropriate drawing, but the present invention is not limited to the same.

A polarizing plate set includes a back side polarizing plate disposed on one surface side of the liquid crystal cell and a front side polarizing plate disposed on the other surface side; and the back side polarizing plate includes a reflective polarizing plate and a first adhesive a layer, a first polarizer, a first protective film, and a second adhesive layer; the front polarizing plate includes a third adhesive layer, a second polarizer, and a second protective film; and the front polarizing plate (2) The thickness dF ( μm ) of the polarizer is subtracted from the thickness dR ( μm ) of the first polarizer of the back side polarizing plate, and the difference dF-dR is Δd ( μm ), 0 μm <Δd<5μm; the angle between the absorption axis of the second polarizer of the front side polarizing plate and the absorption axis of the first polarizer of the back side polarizing plate is 90°±1°.

According to the liquid crystal panel including the polarizing plate kit of the present invention, for example, the liquid crystal panel can be prevented from being peeled off from the touch panel, the backlight unit can be detached, and a display device having a small display unevenness can be obtained.

As shown in Fig. 1, the polarizing plate kit of the present invention includes a back side polarizing plate 10 disposed on one surface side of the liquid crystal cell 30, and a front side polarizing plate 20 disposed on the other surface side. The back side polarizing plate 10 includes a reflective polarizing plate 11 , a first adhesive layer 12 , a first polarizer 13 , and a first Protective film 14 and second adhesive layer 15. In one aspect, the back side polarizing plate 10 may have other layers as needed.

In the other aspect, the back side polarizing plate 10 is formed by sequentially displacing the reflective polarizing plate 11, the first adhesive layer 12, the first polarizer 13, the first protective film 14, and the second adhesive layer 15. board. Further, the back side polarizing plate 10 further has a protective film (not shown) between the first adhesive layer 12 and the first polarizer 13. In other words, the back side polarizing plate 10 can have a protective film on both surfaces of the first polarizer 13.

The front side polarizing plate 20 includes a third adhesive layer 21, a second polarizer 22, and a second protective film 23. The front side polarizing plate 20 may have other layers as needed.

In another aspect, the front side polarizing plate 20 is a polarizing plate in which the third adhesive layer 21, the second polarizer 22, and the second protective film 23 are sequentially laminated. Further, the front side polarizing plate 20 can further have a protective film (not shown) between the third adhesive layer 21 and the second polarizer 22. That is, the front side polarizing plate 20 may have a protective film on both surfaces of the second polarizer 22.

The back side polarizing plate of the present invention is bonded to, for example, a surface of the liquid crystal cell opposite to the side on the viewing side. In one aspect, the back side polarizing plate may be adjacent to a light source provided on the liquid crystal panel, for example, adjacent to a backlight or the like, and bonded to the liquid crystal cell. Further, a double-sided tape having a narrow width may be attached to the edge of the back side polarizing plate, and a backlight unit may be attached.

On the other hand, the front side polarizing plate of the present invention is bonded to, for example, the surface on the viewing side of the liquid crystal cell.

Although not shown in Figure 1, for example, in Figure 1 The polarizing plate set shown in FIG. 2, that is, the back side polarizing plate 10 and the front side polarizing plate 20 may be provided with layers other than the above layers. Further, the polarizers 13 and 22 and the protective films 14 and 23 are usually bonded via an adhesive layer.

In the polarizing plate kit of the present invention, as shown in Fig. 1, the thickness of the second polarizer of the front side polarizing plate 20 is set to dF, and the thickness of the first polarizer of the back side polarizing plate 10 is set to dR. The thickness dF ( μm ) of the second polarizer of the front side polarizing plate 20 minus the thickness dR ( μm ) of the first polarizer of the back side polarizing plate 10 (dF-dR) is set to Δd ( μm ) In the case of 0 μ m < Δd < 5 μ m, it is preferable to have a relationship of 1 μ m < Δd < 5 μ m.

By making the difference Δd ( μm ) of the thickness dF minus the thickness dR in such a range, even the laminated body (liquid crystal panel) of the front side polarizing plate, the glass (liquid crystal cell), and the back side polarizing plate is exposed to a high temperature for a long period of time. (for example, 85 ° C, humidity 5%), the amount of warpage of the laminate is still small. In addition, even if the laminated body of the front side polarizing plate, the glass, and the back side polarizing plate is placed in a hot and humid environment (for example, 60 ° C, humidity: 90%), the warpage of the laminated body can be suppressed.

As described above, the laminated body including the polarizing plate set of the present invention has a small amount of warpage when placed in a hot and humid environment and a high temperature environment, and therefore has a moist heat resistance and heat resistance, and is not in a high temperature environment or a hot and humid environment. It will peel off from the touch panel and the backlight unit will not fall off.

Moreover, it is related to the reduction in display unevenness caused by warpage after high temperature environment and hot and humid environment test.

Further, by having such a relationship of Δd( μm ), the polarizing plate kit of the present invention can be applied to liquid crystal panels having various sizes and thicknesses.

In the present specification, the high temperature environment will be described by taking the temperature of 85 ° C as an example. In the present invention, the high temperature environment means an environment in which a polarizing plate or the like is exposed at a temperature of, for example, 70 ° C to 95 ° C, a humidity of 0% to 20% for at least 30 to 60 minutes.

Further, the hot and humid environment is described as an example of a condition of a temperature of 60 ° C and a humidity of 90%. In the present invention, the moist heat environment means an environment in which, for example, a temperature of 50 ° C to 80 ° C, a humidity of 60% to 95%, a temperature of at least 30 to 60 minutes, exposure of a polarizing plate or the like.

In one aspect, the thickness dR of the first polarizer of the back side polarizing plate is 15 μm or less, and more preferably 0.1 μm or more and 13 μm or less.

Since the back side polarizing plate has a reflective polarizing plate, the thinner the thickness of the first polarizer, the thinner the back side polarizing plate can be achieved.

The measurement of the respective thicknesses of the polarizing plate kit of the present invention can be carried out using a measuring method known in the art.

In the present invention, the angle between the absorption axis of the second polarizer of the front side polarizing plate and the absorption axis of the first polarizer of the back side polarizing plate is 90°±1°, more preferably 90°±0.5°. .

For example, Fig. 2 is a view showing the relationship of the absorption axis of a polarizer according to an aspect of the present invention. In Fig. 2, the absorption axis of the first polarizer of the back side polarizing plate 10 is shown as 10a, and the transmission axis of the first polarizer is shown by 10b. Moreover, the long side of the back side polarizing plate is shown as 10c.

On the other hand, in Fig. 2, the absorption axis of the second polarizer of the front side polarizing plate 20 is 20a, and the transmission axis of the second polarizer is 20b.

In the present invention, the angle formed by the absorption axis 10a of the first polarizer and the absorption axis 20a of the second polarizer is 90° ± 1° as described above. This angle can be expressed, for example, as the angle α of Fig. 2 .

In one aspect, the angle formed by the absorption axis of the first polarizer of the back side polarizing plate and the long side of the back side polarizing plate (first polarizer) is 0°±1°, and in another aspect, The resulting angle is 0 ° ± 0.5 °.

Furthermore, in the present invention, the absorption axis of the second polarizer of the front side polarizing plate is described as the absorption axis of the front side polarizing plate, and the absorption axis of the first polarizer of the back side polarizing plate is included. It is described as the absorption axis of the back side polarizing plate.

In the polarizing plate kit of the present invention, the thickness dF ( μm ) of the second polarizer of the front side polarizing plate is subtracted from the thickness dR ( μm ) of the first polarizer of the back side polarizing plate (dF- When dR) is set to Δd ( μm ), even if the liquid crystal panel having the front side polarizing plate, the glass plate, and the back side polarizing plate is exposed to high temperature conditions and moist heat by 0 μ m<Δd<5 μ m Under the environment, such warpage can still be suppressed.

Further, when the polarizing plate of the present invention is exposed to a high temperature condition, when the polarizing plate is slightly warped, for example, a reflective polarizing plate, a first adhesive layer, a first polarizer, a first protective film, and a second adhesive The agent layer is integrated and warped. Similarly, the third adhesive layer, the second polarizer, and the second protective film are integrally warped.

Therefore, the back side polarizing plate and the front side polarizing plate of the present invention generally do not have interlayer peeling between at least one of the layers.

In addition, there is a case where any of the back side polarizing plate or the front side polarizing plate is warped, and the back side polarizing plate or the front side polarizing plate is warped.

With respect to such warpage, in the present invention, it can be evaluated by measuring the amount of warpage or the like. For example, the amount of warpage can be evaluated by measuring the amount of warpage of the moist heat condition, and can also be evaluated by measuring the amount of warpage of the high temperature condition.

For example, when the amount of warping in the hot and humid conditions is measured, the third adhesive of the front side polarizing plate and the second adhesive layer of the back side polarizing plate are bonded to both surfaces of the glass panel at 60° C. and a humidity of 90%. After standing for 250 hours, a glass panel was placed so that the back side polarizing plate was placed below, and the relative height which floated from the horizontal surface of a measuring stand was measured.

For example, when the amount of warpage in a high temperature state is measured, the third adhesive of the front side polarizing plate and the second adhesive layer of the back side polarizing plate are bonded to both surfaces of the glass panel at 85 ° C and a humidity of 5%. After standing for 250 hours, a glass panel was placed so that the back side polarizing plate was placed below, and the relative height which floated from the horizontal surface of a measuring stand was measured.

[Reflective polarizer]

A reflective polarizing plate, also referred to as a brightness enhancing film, is used as a polarizing conversion element having a function of separating light emitted from a light source (backlight) into a transmitted polarized light and a reflected polarized or scattered polarized light. As described above, by arranging the reflective polarizing plate and the polarizing plate in a predetermined relationship, it is possible to improve the emission efficiency of the linearly polarized light emitted from the polarizing plate by using the reflected light or the reflected light of the scattered polarized light. For example, the reflective polarizing plate is in contact with the first adhesive layer.

The reflective polarizing plate may be, for example, an anisotropic reflective polarizer. An example of an anisotropic reflective polarizer is an anisotropic multiple film that penetrates a linearly polarized light in a vibration direction and reflects a linearly polarized light in the other vibration direction. A specific example is DBEF manufactured by 3M Company (Japanese Patent Laid-Open No. 4-268505) Bulletin, etc.). Such a reflective polarizing plate is a reflective polarizing plate in which a multilayer laminated body composed of at least two layers of films having different refractive index anisotropy is stretched. Therefore, such a reflective polarizing plate has at least two films, and at least two layers of the stretched film have different refractive index anisotropies.

Another example of the anisotropic reflective polarizer is a composite of a cholesteric liquid crystal layer and a λ/4 plate, and a specific example thereof is PCF manufactured by Nitto Denko Corporation (Japanese Laid-Open Patent Publication No. Hei 11-231130, etc.). Still another example of the anisotropic reflective polarizer is a reflective grating polarizer, and a specific example thereof is a metal grating reflective polarizer that performs fine processing on a metal and also emits reflected polarized light in a visible light region (US Patent No. 6288840, etc.) A metal microparticle is added to a polymer matrix and stretched (Japanese Patent Laid-Open No. Hei 8-184701).

On the opposite side of the reflective polarizer from the first adhesive layer, an optical layer such as a hard coat layer, an antiglare layer, a light diffusion layer, and a retardation layer having a phase difference of 1/4 wavelength may be provided. . By the formation of the optical layer, the adhesion to the backlight tape and the uniformity of the displayed image can be improved. The thickness of the reflective polarizing plate may be about 5 to 100 μm , but it is preferably 10 to 40 μm , more preferably 10 to 30 μm from the viewpoint of reducing warpage of the liquid crystal panel.

In the polarizing plate set of the present invention, the surface of the reflective polarizing plate on the side of the first adhesive layer can be surface-activated. This surface activation treatment is performed before the bonding of the reflective polarizing plate and the first adhesive layer. As a result, in the hot and humid environment, peeling between the first adhesive layer and the reflective polarizing plate is less likely to occur, and a polarizing plate excellent in wet heat durability can be obtained.

The surface activation treatment may be a hydrophilization treatment of the surface, a dry treatment, or a wet treatment. Examples of the dry treatment include, for example, corona treatment, plasma treatment, discharge treatment by glow discharge treatment, flame treatment, ozone treatment, UV ozone treatment, ionization active ray treatment such as ultraviolet treatment, electron beam treatment, and the like. As the wet treatment, for example, ultrasonic treatment using a solvent such as water or acetone, alkali treatment, primer treatment, or the like can be exemplified. These treatments may be carried out separately or in combination of two or more.

Among them, the surface activation treatment is preferably corona treatment and/or plasma treatment from the viewpoint of the peeling suppression effect of the reflective polarizing plate in a hot and humid environment and the productivity of the polarizing plate. According to the surface activation treatment, even when the thickness of the reflective polarizing plate is small, for example, 30 μm or less, peeling between the first adhesive layer and the reflective polarizing plate in a moist heat environment can be effectively suppressed. Further, the surface activation treatment may be performed on the surface of the first adhesive layer on the side of the brightness-reflective polarizing plate.

[1st adhesive layer]

The first adhesive layer is a layer interposed between the first polarizer and the reflective polarizer. The first adhesive layer is typically bonded to the first polarizer and the first adhesive The layers of the agent layer are directly laminated to the polarizer.

The first adhesive layer may be composed of an adhesive composition containing, for example, an acrylic, rubber, amine ester, ester, polyoxyn, or polyvinyl ether resin as a main component. Among them, an adhesive composition containing an acrylic resin excellent in transparency, weather resistance, heat resistance, and the like as a matrix polymer is suitable. The adhesive composition may be an active energy ray hardening type or a thermosetting type.

As the acrylic matrix polymer, for example, butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, or 2-ethylhexyl (meth)acrylate may be suitably used. A (meth)acrylate type matrix polymer, and a copolymerization type matrix polymer which used two or more types among these (meth)acrylates. For the matrix polymer, it is preferred to copolymerize the polar monomer. Examples of the polar monomer include, for example, (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, and (meth)acrylic acid N. A monomer having a carboxyl group, a hydroxyl group, a decylamino group, an amine group, an epoxy group or the like of N-dimethylaminoethyl ester or (meth)acrylic acid glyceride.

The adhesive composition usually further has a crosslinking agent. The crosslinking agent may, for example, be a metal ion having a valence of 2 or more and a metal carboxylic acid salt formed between the carboxyl group; a polyamine compound having a guanamine bond with a carboxyl group; and a polyepoxy compound; A polyalcohol which forms an ester bond with a carboxyl group; a polyisocyanate compound which forms a guanamine bond with a carboxyl group. Among them, a polyisocyanate compound is preferred.

The active energy ray-curable adhesive composition refers to an irradiation with an active energy ray such as ultraviolet rays or electron rays. Further, it has an adhesive property, and has an adhesive property before being irradiated with an active energy ray, and can be adhered to an adhesive such as a film, and an adhesive composition capable of adjusting the adhesive force by irradiation hardening of an active energy ray. The active energy ray-curable adhesive composition is preferably an ultraviolet curing type. The active energy ray-curable adhesive composition further contains an active energy ray-polymerizable compound in addition to the matrix polymer and the crosslinking agent. Further, a photopolymerization initiator, a photosensitizer, or the like may be contained as needed.

The adhesive composition may include fine particles for imparting light scattering properties; beads; a resin other than the matrix polymer; an adhesive; a filler; an antioxidant; a UV absorber; a pigment;

The first adhesive layer can be formed by applying an organic solvent diluent of the above-mentioned adhesive composition to a substrate and drying it. The substrate may be a polarizer, a reflective polarizer, a separator, or the like. When the active energy ray-curable adhesive composition is used, the active energy ray can be irradiated by the formed adhesive layer to become a desired cured product.

The first adhesive layer is preferably in the temperature range of 23 to 80 ° C and exhibits a storage elastic modulus of 0.15 to 1.2 MPa. Thereby, in a high-temperature and hot-heat environment, the dimensional change which is easy to occur accompanying the shrinkage of the polarizer can be suppressed, and the durability of the polarizing plate can be improved. Further, a liquid crystal panel equipped with a polarizing plate (for example, a liquid crystal panel for a small-sized portable terminal) can suppress the variation of the polarizing plate even when placed in a high temperature and a hot and humid environment, so that the liquid crystal panel can be improved. Reliability.

The phrase "the storage elastic modulus of 0.15 to 1.2 MPa in the temperature range of 23 to 80 ° C" means any temperature in the range. The storage elastic modulus is a value within the above range. The storage elastic modulus is usually decreased as the temperature rises. Therefore, if the storage elastic modulus at 23 ° C and 80 ° C falls within the above range, the temperature in the range can be regarded as the storage elastic modulus in the above range. number. The storage elastic modulus of the first adhesive layer can be measured using a commercially available viscoelasticity measuring device, and is measured by, for example, a viscoelasticity measuring device "DYNAMIC ANALYZER RDA II" manufactured by REOMETRIC Co., Ltd. as shown in the examples below. .

As a method of adjusting the storage elastic modulus to the above range, for example, an oligomer is further added to the adhesive composition containing the matrix polymer and the crosslinking agent, and specifically, an amine ester acrylate oligomer is further added. The material becomes an active energy ray hardening type adhesive composition (preferably an ultraviolet curing type adhesive composition). More preferably, the active energy ray is irradiated to moderately cure the adhesive layer.

The thickness of the first adhesive layer may be 30 μm or less. It is preferably 25 μm or less, particularly preferably 20 μm or less, and particularly preferably 15 μm or less. By the thickness of the first adhesive layer being in such a range, good workability can be maintained and the dimensional change of the polarizing plate can be suppressed. Further, the thickness of the first adhesive layer can be appropriately adjusted so that the thickness of the interlayer is within a predetermined range.

[Polarizer]

The polarizer is an absorption type polarizer having a property of absorbing a linearly polarized light having a vibration plane parallel to its absorption axis and penetrating a linearly polarized light having a vibration plane perpendicular to the absorption axis (parallel to the transmission axis). Polarized plate cover of the present invention The first polarizer and the second polarizer used in the group may be the same polarizer as long as the thickness thereof has a predetermined relationship, or may be different polarizers. For example, a polarizing film oriented to a polyvinyl alcohol-based resin film can be suitably used by using a dichroic dye. The polarizer can be produced, for example, by a method comprising the steps of: uniaxially stretching a polyvinyl alcohol-based resin film; and dyeing the polyvinyl alcohol-based resin film by a dichroic dye to obtain a dichroic dye a step of adsorbing; a step of treating a polyvinyl alcohol-based resin film having a dichroic dye adsorbed thereon with a boric acid aqueous solution; and a step of washing with water after treatment with an aqueous solution of boric acid.

As the polyvinyl alcohol-based resin, a polyvinyl acetate-based resin saponified can be used. Examples of the polyvinyl acetate-based resin include, in addition to the polyvinyl acetate of a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate. 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 about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, an aldehyde-modified polyvinyl alcohol formaldehyde, a polyvinyl acetal or the like may also be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually from about 1,000 to 10,000, preferably from about 1,500 to 5,000. The average degree of polymerization of the polyvinyl alcohol-based resin can be determined in accordance with JIS K 6726.

A film of a polyvinyl alcohol-based resin can be used as a raw material film of a polarizer (polarizing film). The method of forming the film of the polyvinyl alcohol-based resin is not particularly limited, and a conventional method can be employed. The film thickness of the polyvinyl alcohol-based raw material film is not particularly limited. However, in order to make the thickness of the polarizer, for example, 15 μm or less, a raw material film of about 5 to 35 μm is preferably used.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be carried out before the dyeing of the dichroic dye, simultaneously with the dyeing, or after the dyeing. When uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before boric acid treatment or in boric acid treatment. Moreover, uniaxial stretching can also be performed at these plurality of stages.

In the case of uniaxial stretching, uniaxial stretching is performed between rollers having different rotational speeds, and uniaxial stretching can also be performed using a heat roller. Further, the uniaxial stretching may be a dry stretching in which the film is stretched in the air, or may be a wet stretching in which the polyvinyl alcohol-based resin film is stretched in a state of swelling using a solvent. The stretching ratio is usually about 3 to 8 times.

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

As a dyeing treatment by iodine, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in the aqueous solution may be about 0.01 to 1 part by weight per 100 parts by weight of water. The potassium iodide may be contained in an amount of about 0.5 to 20 parts by weight per 100 parts by weight of the water. Moreover, the temperature of the aqueous solution may be about 20 to 40 °C. On the other hand, as a dyeing treatment by a dichroic organic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic organic dye is usually employed. An aqueous solution containing a dichroic organic dye may also contain an inorganic salt such as sodium sulfate as a dyeing auxiliary. The content of the dichroic organic dye of the aqueous solution may be from about 1 × 10 ^-4 to about 10 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution may be about 20 to 80 °C.

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

The boric acid content of the aqueous solution containing boric acid may be about 2 to 15 parts by weight per 100 parts by weight of water. The amount of potassium iodide of the aqueous solution may be from about 0.1 to 15 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution may be 50 ° C or higher, for example, 50 to 85 ° C.

The polyvinyl alcohol-based resin film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment can be carried out, for example, by immersing a boric acid-treated polyvinyl alcohol-based resin film in water. The water washing treatment can be carried out by water containing potassium iodide, and the temperature of the water treated with water is usually about 5 to 40 °C.

After washing with water, it was dried to obtain a polarizer. The drying treatment can be carried out using a hot air dryer or a far infrared heater. The thickness of the polarizer is preferably 15 μm or less, and more preferably 13 μm or less. The thickness of the polarizer is usually 4 μm or more. In one aspect, the thickness dR of the first polarizer of the back side polarizing plate is 15 μm or less. In one aspect, the thickness dF of the second polarizer of the front side polarizing plate is 15 μm or less, and more preferably 0.1 μm or more and 13 μm or less.

Further, the thickness of the polarizer can be appropriately adjusted within the range not departing from the scope of the invention.

[protective film]

The first protective film is a film laminated on the surface of the first polarizer opposite to the first adhesive layer. The second protective film is a film laminated on the surface of the second polarizer opposite to the third adhesive layer. The first protective film and the second protective film may be the same film or different films.

The protective film may have a translucent (preferably optically transparent) thermoplastic resin, and may be, for example, a chain polyolefin resin (such as a polypropylene resin) or a cyclic polyolefin resin (a decene-based resin or the like). Polyolefin-based resin; cellulose-based resin such as triethyl fluorenyl cellulose or diethyl hydrazine cellulose; polyester resin such as polyethylene terephthalate or polybutylene terephthalate Polycarbonate resin; acrylic resin such as (meth)acrylic resin; polystyrene resin; polyvinyl chloride resin; acrylonitrile/butadiene/styrene resin; acrylonitrile/styrene system Resin; polyvinyl acetate resin; polyvinylidene chloride resin; polyamine resin; polyacetal resin; modified polyphenylene ether resin; polyfluorene resin; polyether oxime resin; An ester resin; a polyamidoximine resin; a film composed of a polyimine resin or the like. Among them, a polyolefin resin or an acrylic resin is preferably used, and a cyclic polyolefin resin is particularly preferably used.

In addition to a homopolymer of a chain olefin such as a polyethylene resin or a polypropylene resin, a copolymer containing two or more kinds of chain olefins may be mentioned as the chain polyolefin resin.

The cyclic polyolefin resin is a general term for a resin polymerized by using a cyclic olefin as a polymerization unit. Specific examples of the cyclic polyolefin-based resin include a ring-opening (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, and copolymerization of a cyclic olefin with a chain olefin such as ethylene or propylene. (representatively, a random copolymer), and such a graft copolymer modified with an unsaturated carboxylic acid or a derivative thereof, and the like, and the like. Among them, a norbornene-based resin which uses a norbornene-based monomer such as a norbornene or a polycyclic norbornene-based monomer as a cyclic olefin is preferable. In a preferred aspect, the protective film of the present invention comprises a cyclic polyolefin resin.

The term "cellulosic resin" means a part or all of a hydrogen atom of a hydroxyl group of cellulose obtained from raw material cellulose such as cotton linter, wood pulp (broadwood pulp, and conifer pulp) via an ethyl ketone group, a propyl group, and/or A cellulose organic acid ester or a cellulose mixed organic acid ester substituted with a butyl group. For example, it is composed of cellulose acetate, propionate, butyrate, and such mixed esters.

A preferred example of the acrylic resin film is a film containing a methyl methacrylate resin. The methyl methacrylate-based resin refers to a polymer containing 50% by weight or more of a methyl methacrylate unit. The content of the methyl methacrylate unit is preferably 70% by weight or more, and may be 100% by weight. The methyl methacrylate unit is a 100% by weight polymer, which is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.

The methyl methacrylate resin is usually coexisted by a radical polymerization initiator and a chain transfer agent used as needed. A monofunctional monomer containing methyl methacrylate as a main component and a polyfunctional monomer used as needed are polymerized.

Examples of the monofunctional monomer copolymerizable with methyl methacrylate include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, and benzoyl methacrylate. Methyl acrylates other than methyl methacrylate such as ester, 2-ethylhexyl methacrylate and 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate Acrylates such as phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate; methyl 2-(hydroxymethyl)acrylate, methyl 3-(hydroxyethyl)acrylate Hydroxy acrylates such as ethyl 2-(hydroxymethyl)acrylate and butyl 2-(hydroxymethyl)acrylate; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene ; substituted styrenes such as vinyl toluene and α-methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated anhydrides such as maleic anhydride and citraconic anhydride; and phenyl mala Unsaturated by imine and cyclohexylmaleimide Imines. These monomers may be used alone or in combination of two or more.

Examples of the polyfunctional monomer copolymerizable with methyl methacrylate include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and triethylene glycol di(a). Ethylene glycol such as acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, and tetradecaethylene glycol (meth)acrylate or oligomer thereof The hydroxyl group at both ends is esterified with acrylic acid or methacrylate; the hydroxyl group at both ends of propylene glycol or its oligomer is esterified with acrylic acid or methacrylate; neopentyl glycol di(methyl) a hydroxyl group of a divalent alcohol such as acrylate, hexanediol di(meth)acrylate or butanediol di(meth)acrylate, which is esterified with acrylic acid or methacrylic acid; epoxy of bisphenol A and bisphenol A The alkyl group or the hydroxyl group at both ends of the halogen substituent is acidified by acrylic acid or methacrylate; the polyol such as trimethylolpropane and pentaerythritol is esterified with acrylic acid or methacrylic acid; The hydroxyl group at the end of the ring is added to the epoxy group of glycerin or methacrylate; in succinic acid, adipic acid, terephthalic acid, phthalic acid, halogen substitutes, etc. a dibasic acid, and an epoxy group having a glycerin acrylate or a methacrylic acid glyceride in a ring-opening addition to such an alkylene oxide adduct; a (meth)acrylic acid aromatic ester; and divinylbenzene Diaryl compounds and the like. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

The methyl methacrylate-based resin may be a modified methyl methacrylate-based resin which is modified by performing a reaction between functional groups of the resin. The reaction may, for example, be a polymer chain in-methanol condensation reaction of a methyl ester group of methyl acrylate with a hydroxyl group of methyl 2-(hydroxymethyl) acrylate, and a carboxyl group of acrylic acid and 2-(hydroxymethyl)acrylic acid. A polymer chain internal dehydration condensation reaction of a hydroxyl group of an ester.

It is also useful to control the retardation value of the protective film to a value suitable for the liquid crystal panel. For example, in a liquid crystal panel of a transverse electric field (IPS) mode, it is preferable to use a film having a substantially phase difference value of zero. The substantially phase difference value is 0, which means that the in-plane phase difference of the wavelength of 590 nm is 10 nm or less, and the absolute value of the thickness direction phase difference of the wavelength of 590 nm is 10 nm. Next, the absolute value of the retardation value in the thickness direction of the wavelength of 480 to 750 nm is 15 nm or less.

According to the mode of the liquid crystal panel, the protective film can be stretched and/or shrunk to give a suitable phase difference.

The thickness of the protective film may be from about 1 to 30 μm , preferably from 5 to 25 μm , more preferably from 5 to 20 μm , from the viewpoints of strength, workability and the like. When the thickness is within this range, the polarizer can be mechanically protected, and the polarizer does not shrink even when exposed to a moist heat environment, and maintains stable optical characteristics. Further, the thickness of the protective film can be appropriately adjusted so that the thickness of the interlayer is within a predetermined range.

The protective film can be attached to the polarizer via an adhesive layer. As the adhesive for forming the adhesive layer, a water-based adhesive or an active energy ray-curable adhesive can be used.

Examples of the water-based adhesive include an adhesive containing a polyvinyl alcohol-based resin aqueous solution, and an aqueous two-liquid amine ester-based emulsified adhesive. Among them, an adhesive containing an aqueous solution of a polyvinyl alcohol-based resin is suitably used. As the polyvinyl alcohol-based resin, in addition to the vinyl alcohol homopolymer obtained by subjecting polyvinyl acetate of a homopolymer of vinyl acetate to saponification, vinyl acetate and copolymerizable with vinyl acetate can be used. The polyvinyl alcohol-based copolymer obtained by the saponification treatment of the copolymer of the other monomer, or the modified polyvinyl alcohol-based polymer partially modified by the hydroxyl group. The aqueous binder may include a crosslinking agent such as an aldehyde compound, an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.

In the case of using a water-based adhesive, it is preferred to carry out a drying step for removing water contained in the aqueous binder after bonding the polarizer and the protective film. After the drying step, a curing step of, for example, curing at a temperature of about 20 to 45 ° C may be provided.

The active energy ray-curable adhesive agent is an adhesive which is cured by irradiation with an active energy ray such as ultraviolet rays, and includes, for example, a polymerizable compound and a photopolymerization initiator, and a photoreactive resin, including a binder. Resin resin and photoreactive cross-linking agent, etc. Examples of the polymerizable compound include photocurable epoxy-based monomers, photocurable acrylic monomers, and photocurable amine ester-based monomers, and photopolymerizable monomers derived from photopolymerizable monomers. Things. Examples of the photopolymerization initiator include those which generate active species such as neutral radicals, anionic radicals, and cationic radicals by irradiation of active energy rays such as ultraviolet rays. As the active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator, for example, a photocurable epoxy monomer and a photocationic polymerization initiator are preferably used.

When the active energy ray-curable adhesive is used, after the polarizer and the protective film are bonded, a drying step is performed as needed, and then a curing step of curing the active energy ray-curable adhesive by irradiation with the active energy ray is performed. The light source of the active energy ray is not particularly limited, but is preferably ultraviolet light having a light-emitting distribution of a wavelength of 400 nm or less. Specifically, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a fluorescent lamp, and a black light can be used. Lights, microwaves, mercury lamps, metal halide lamps, etc.

When the polarizer and the protective film are bonded, saponification treatment, corona treatment, plasma treatment, or the like may be performed on at least one of the bonding surfaces.

[2nd and 3rd adhesive layers]

As the adhesive for forming the second adhesive layer and the third adhesive layer, any conventional one can be appropriately selected as long as it is exposed to a high temperature environment, a hot and humid environment, or a high temperature and low temperature environment. It is sufficient that the degree of adhesion such as peeling does not occur. Specifically, for example, an acrylic adhesive, a polyoxynoxy adhesive, a rubber adhesive, and the like are used, and in terms of transparency, weather resistance, heat resistance, and workability, an acrylic adhesive is used. good.

Further, the same type of adhesive may be used for the first adhesive layer, the second adhesive layer, and/or the third adhesive layer, and different types of adhesives may be used.

In a preferred embodiment, the second adhesive layer and the third adhesive layer are formed of an acrylic adhesive.

Adhesives, plasticizers, fillers containing glass fibers, glass beads, metal powders, other inorganic powders, pigments, colorants, antioxidants, UV absorbers, and anti-adhesives may be appropriately formulated as needed. Various additives such as an electrostatic agent and a decane coupling agent.

The adhesive layer is usually formed by applying a solution of an adhesive to a release sheet and drying it. For the coating on the release sheet, for example, a roll coating method such as a reverse coating method or a gravure coating method, a spin coating method, a screen coating method, a fountain coating method, a dip coating method, or a spray coating method can be employed. Wait. The release sheet provided with the adhesive layer can be utilized by a method of transferring it or the like. The thickness of the adhesive layer is usually about 3 to 30 μm , preferably 10 to 30 μm , more preferably 10 to 25 μm . In a preferred embodiment, the second adhesive layer and the third adhesive layer have such a thickness that the destruction of the polarizing plate can be suppressed, and when the liquid crystal display device is assembled, light leakage at the end portion of the liquid crystal panel can be suppressed. In addition, the thickness of the second adhesive layer and the third adhesive layer can be appropriately adjusted so that the thickness of the interlayer is within a predetermined range.

The storage elastic modulus at 80 ° C of the second adhesive layer and the third adhesive layer is preferably 0.025 MPa or more, and more preferably 0.07 MPa or more. If the storage elastic modulus of the adhesive layer is less than 0.025 MPa, aggregation failure occurs in the second adhesive layer and the third adhesive layer. When the aggregation damage is remarkable, not only the appearance of the polarizing plate is adversely affected, but also the assembly is performed. In the liquid crystal display device, light leakage occurs at the end portion of the liquid crystal panel, which adversely affects the display. The storage elastic modulus at 80 ° C of the second adhesive layer and the third adhesive layer is preferably 1.1 MPa or less, preferably 0.9 MPa or less. When the storage elastic modulus at 80 ° C exceeds 1.1 MPa, the heat resistance durability of the second adhesive layer, the third adhesive layer, and the glass or the panel is deteriorated, and it is easy to generate bubbles between the layers.

A separator may be provided in order to protect the surface of the second adhesive layer and the third adhesive layer before bonding them to other members. For example, a film made of a transparent resin such as polyethylene terephthalate can be subjected to a treatment by a polyfluorene-based release agent.

[Method of Manufacturing Back Side Polarizing Plate]

The back side polarizing plate of the present invention is produced, for example, by a step of performing a surface activation treatment on the surface of the reflective polarizing plate on the first adhesive layer side, and the above-described surface activation treatment. The step of laminating the first adhesive layer on the surface.

Further, the back side polarizing plate of the present invention includes, for example, a first protective film bonded to one surface of the polarizer via an adhesive layer, and a second adhesive layer on the opposite side of the first protective film from the first polarizer. The layer of the first polarizer is bonded to the surface of the first polarizer opposite to the first protective film; and the layer of the first adhesive layer is opposite to the first polarizer. By the above steps, the back side polarizing plate of the present invention is obtained. Further, the separator may be temporarily attached to the outer surface of the second adhesive layer, or the surface of the first adhesive layer to be bonded to the reflective polarizing plate may be surface-activated.

The method of bonding the reflective polarizing plate to the first adhesive layer may be a sheet-type bonding method, or may be a sheet/roll composite bonding method as described in JP-A-2004-262071. Moreover, it can be produced in a long strip shape, and it is also useful by a roll-to-roll bonding means when the required amount is large.

Thus, the method for producing the back side polarizing plate of the present invention can be produced by a method known in the art.

[Manufacturing method of front side polarizing plate]

The method for producing the front side polarizing plate of the present invention can be produced by a method known in the art. For example, via the above-described back side polarizing plate The front side polarizing plate can be obtained by the same steps of the manufacturing method.

[LCD panel]

The polarizing plate kit of the present invention is suitably applied to a liquid crystal panel. The liquid crystal panel includes a liquid crystal cell and a polarizing plate of the present invention bonded to the surface of the liquid crystal cell. The bonding of the back side polarizing plate to the liquid crystal cell can be performed via the second adhesive layer. The back side polarizing plate of the present invention is generally used as a polarizing plate disposed on the backlight side of the liquid crystal cell.

On the other hand, the front side polarizing plate can be bonded to the liquid crystal cell via the third adhesive layer. The front side polarizing plate of the present invention is generally used as a polarizing plate disposed on the viewing side of the liquid crystal cell.

In one aspect, a liquid crystal panel is provided, which is provided with a liquid crystal cell and a pair of polarizing plates disposed on both sides of the liquid crystal cell; The pair of polarizing plates are the polarizing plate sets described above; The second protective film, the second polarizer, the third adhesive layer, the liquid crystal cell, the second adhesive layer, the first protective film, the first polarizer, the first adhesive layer, and the reflective polarizing plate are sequentially laminated.

The driving method of the liquid crystal cell can be any conventionally known method, preferably an IPS mode. The liquid crystal panel using the polarizing plate of the present invention has excellent wet heat durability.

In the present invention, an organic electroluminescence display device can be obtained by bonding each polarizing plate to an organic electroluminescence display via a second adhesive layer or a third adhesive layer.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the invention is not limited to the examples. In the examples, the % or the part of the content or the amount used is a weight basis unless otherwise specified.

Further, the thickness of the film was measured in accordance with the following.

(1) Determination of the thickness of the film:

The measurement was carried out using a digital micrometer "MH-15M" manufactured by Nikon Co., Ltd.

[Production of polarizer] (Manufacturing example P1)

A polyvinyl alcohol film having a thickness of 60 μm (having an average degree of polymerization of about 2400 and a degree of saponification of 99.9 mol% or more) was longitudinally uniaxially stretched by about 5 times by dry stretching, and then immersed in a state of being kept tight. After 1 minute of pure water at 60 ° C, it was immersed in an aqueous solution of 28 ° C in a weight ratio of iodine / potassium iodide / water of 0.05/5 / 100 for 60 seconds. Then, it was immersed in an aqueous solution of 72 ° C in a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 for 300 seconds. Subsequently, the film was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C to obtain a polarizer having a thickness of 23 μm oriented to a polyvinyl alcohol film. Hereinafter, the polarizer is described as a polarizer (23 μm ).

(Manufacturing example P2)

A polyvinyl alcohol film having a thickness of 30 μm (average degree of polymerization of about 2400, a degree of saponification of 99.9 mol% or more) was longitudinally uniaxially stretched by about 5 times by dry stretching, and then immersed in a state of being kept tight. After 1 minute of pure water at 60 ° C, it was immersed in an aqueous solution of 28 ° C in a weight ratio of iodine / potassium iodide / water of 0.05/5 / 100 for 60 seconds. Then, it was immersed in an aqueous solution of 72 ° C in a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 for 300 seconds. Subsequently, the mixture was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C to obtain a polarizer having a thickness of 12 μm oriented to a polyvinyl alcohol film. Hereinafter, the polarizer is described as a polarizer (12 μm ).

(Manufacturing example P3)

In the same manner as in the production of the stretching ratio of Production Example P2, a polarizer having a thickness of 11 μm oriented to the polyvinyl alcohol film was obtained by the same method. Hereinafter, the polarizer is described as a polarizer (11 μm ).

(Manufacturing example P4)

A polyvinyl alcohol film having a thickness of 20 μm (average degree of polymerization of about 2,400, a degree of saponification of 99.9 mol% or more) was uniaxially stretched by about 5 times by dry stretching, and then immersed in 60 while being kept tight. After 1 minute of pure water at ° C, it was immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.05/5/100 at 28 ° C for 60 seconds. Then, it was immersed in an aqueous solution of potassium iodide/boric acid/water in a weight ratio of 8.5/8.5/100 at 72 ° C for 300 seconds. Subsequently, the film was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C to obtain a polarizer having an iodine adsorption orientation of 7 μm in a thickness of a polyvinyl alcohol film. Hereinafter, the polarizer is described as a polarizer (7 μm ).

(Manufacturing example P5)

In the same manner as in the production of the stretching ratio of Production Example P4, a polarizer having a thickness of 8 μm oriented to the polyvinyl alcohol film was obtained by the same method. Hereinafter, the polarizer is described as a polarizer (8 μm ).

[Example of preparation of the first adhesive layer]

An organic solvent solution in which an amine ester acrylate oligomer and an isocyanate crosslinking agent are added to a copolymer of butyl acrylate and acrylic acid, and is applied to a thickness of 5 μm after drying by a die coater. The release treated surface of a polyethylene terephthalate film (release film) having a thickness of 38 μm which was subjected to release treatment was dried and dried to obtain an adhesive sheet.

[Preparation Example of Second Adhesive Layer and Third Adhesive Layer]

A commercially available adhesive sheet of an acrylic adhesive layer having a thickness of 20 μm was provided on the release treatment surface of a polyethylene terephthalate film (release film) having a thickness of 38 μm subjected to release treatment. The amine acrylate oligomer was not formulated.

[Reflective polarizer]

As the reflective polarizing plate-1, "Advanced Polarized Film, Version 3" (thickness: 26 μm) manufactured by 3M Company was used.

[protective film]

Use the following protective film.

HC-TAC: a triethylenesulfonated cellulose film (manufactured by Toppan TOMOEGAWA optical film Co., Ltd., 25KCHC-TC) having a thickness of 32 μm and a hard-coated surface.

TAC: Triethylenesulfonated cellulose film (TAC) having a thickness of 25 μm [trade name "KC2UA" manufactured by Konica Minolta Co., Ltd.]

COP-1: a decene-based resin film having a thickness of 23 μm without extension (trade name "ZEONOR", manufactured by ZEON CORPORATION, Japan]

COP-2: a non-stretched decene-based resin film having a thickness of 13 μm (trade name "ZEONOR", manufactured by ZEON CORPORATION, Japan]

[Preparation of water-based adhesive]

3 parts by weight of a carboxyl group-modified polyvinyl alcohol ("KL-318" manufactured by Kuraray Co., Ltd.) was dissolved in 100 parts by weight of water to prepare a polyvinyl alcohol aqueous solution. In the aqueous solution obtained, a water-soluble polyamine epoxy resin ("SUMIREZ RESIN 650 (30)" manufactured by Tsuchoka Chemical Industry Co., Ltd. was mixed at a ratio of 1.5 parts by weight based on 100 parts by weight of water, and the solid content concentration was 30% by weight. ], a water-based adhesive was obtained.

[Example of the front side polarizer] (Example of preparation of front side polarizer A)

Apply a water-based adhesive to one side of the polarizer (12 μm ), paste the HC-TAC as the second protective film, and use the above-mentioned adhesive on the opposite side to laminate COP-1 by drying at 80 °C. Minutes, fit the protective film and polarizer. After lamination, it was aged at 168 ° C for 168 hours. Further, the third adhesive layer was bonded to the surface of the COP-1 opposite to the polarizer. This laminated body was used as the front side polarizing plate A. Further, the laminated body has a rectangular shape with a long side length of 155.25 mm and a short side length of 95.90 mm.

(Example of preparation of front side polarizing plate B)

Except that the polarizer of the front side polarizing plate A was changed to a polarizer (11 μm ), it was produced in the same manner as the front side polarizing plate A. This laminated body is set as the front side polarizing plate B.

(Example of preparation of front side polarizing plate C)

Except that the polarizer of the front side polarizing plate A was changed to a polarizer (23 μm ), it was produced in the same manner as the front side polarizing plate A. This laminated body is set as the front side polarizing plate C.

[Example of Production of Back Side Polarizing Plate] (Example of preparation of back side polarizing plate A)

A water-based adhesive was applied to one side of a polarizing plate (11 μm ), and TAC was applied as a protective film, and the above-mentioned adhesive was used on the opposite side to laminate a COP-2 as a first protective film by 80 ° C. Dry for 5 minutes, and apply a protective film and a polarizer. After lamination, it was aged at 168 ° C for 168 hours. Further, the second adhesive layer was bonded to the surface of the COP-2 opposite to the polarizer. Further, a reflective polarizing plate was bonded to the surface on the opposite side of the polarizer of the TAC via a first adhesive. This laminated body is set as the back side polarizing plate A. Further, the laminated body has a rectangular shape with a long side length of 155.25 mm and a short side length of 95.90 mm.

(Example of Production of Back Side Polarizing Plate B)

A water-based adhesive was applied to one side of the polarizer (8 μm ), and COP-2 was laminated as the first protective film, and the protective film and the polarizer were bonded by drying at 80 ° C for 5 minutes. Further, the second adhesive layer was bonded to the surface of the COP-2 opposite to the polarizer. Further, on the surface of the polarizer opposite to the first protective film, the reflective polarizing plate is bonded via the first adhesive. This laminated body is set as the back side polarizing plate B. Further, the laminated body has a rectangular shape with a long side length of 155.25 mm and a short side length of 95.90 mm.

(Example of Production of Back Side Polarizing Plate C)

The polarizer of the back side polarizing plate B was changed to a polarizer (7 μm ), and was produced in the same manner as the back side polarizing plate B. This laminated body is set as the back side polarizing plate C.

(Example of preparation of the back side polarizing plate D)

The polarizer of the back side polarizing plate A was changed to a polarizer (12 μm ), and was produced in the same manner as the back side polarizing plate A. This laminated body is set as the back side polarizing plate D.

The configurations of the polarizing plates of the examples and comparative examples thus obtained are shown in Table 1. Further, the physical property evaluation of each of the obtained polarizing plates was carried out in accordance with the following description. The results are shown in Table 1.

[Measurement of warpage amount] (production of laminate)

With respect to the polarizing plate produced above, the amount of warpage was measured by the following method. First, the surface of the second adhesive layer on the side opposite to the first protective film was bonded to a glass having a thickness of 0.4 mm (Model: EAGLE XG (registered trademark), manufactured by Corning Co., Ltd.). .

Then, the surface of the third adhesive layer of the front side polarizing plate opposite to the second polarizer is bonded to the surface of the glass opposite to the side of the second adhesive layer.

The angle between the absorption axis of the second polarizer of the front side polarizing plate and the absorption axis of the first polarizer of the back side polarizing plate is 90°, and the first side of the back side polarizing plate is bonded. A laminated body was produced such that the angle formed by the absorption axis of the polarizer and the long side of the back side polarizing plate was 0°.

(warping in hot and humid environment)

The laminate having the structure of the back side polarizing plate/glass/front side polarizing plate was allowed to stand in an environment of 60° C. and a humidity of 90% for 250 hours. The laminated body was taken out from the test tank, and placed on a measuring stand of a two-dimensional measuring instrument (NEXIV (registered trademark) MR-12072, manufactured by Nikon Co., Ltd.) so that the front side polarizing plate was on the upper side.

Then, the surface of the measuring table was focused, and focused on the glass sample surface at 25 points on the basis of this, and the height from the reference focus was measured. The difference between the maximum value and the minimum value of the height of the measurement point at 25 points was taken as the amount of warpage. Specifically, the point 40 shown in Fig. 3 is used as a measurement point. The 25 points shown in Fig. 3 are set to the inside from the end of the polarizing plate. At the point of the 7 mm area, the short side direction is provided with an interval of about 20 mm, and the long side direction is provided with an interval of about 35 mm. Further, in Fig. 3, reference numeral 50 denotes a polarizing plate, and 60 denotes a glass plate.

The judgment is as follows. The results are shown in Table 1.

Further, in the examples, the floating, peeling, and floating and peeling of the respective layers were not confirmed in any of the samples.

<determination>

The case where the amount of warpage of the glass sample which was left to stand in a hot and humid environment was less than 0.6 mm was "○".

The case where the amount of warpage of the glass sample which was left to stand in a hot and humid environment was 0.6 mm or more was "X".

(warping in high temperature environment)

The laminate was allowed to stand in an environment of 85 ° C and a humidity of 5% for 250 hours so that the front side polarizing plate having the laminated body of the back side polarizing plate/glass/front side polarizing plate was on the upper side. The laminate was taken out from the test cell, and placed on a measurement stand of a two-dimensional measuring instrument (NEXIV (registered trademark) MR-12072, manufactured by Nikon Corporation) so that the front side polarizing plate was on the upper side. The amount of warpage was measured in the same manner as the above method.

<determination>

When the amount of warpage of the glass sample which was left to stand in a high temperature environment was 0.6 mm or less, it was "○".

When the amount of warpage of the glass sample which was left to stand in a high temperature environment exceeded 0.6 mm, it was "X".

As a result of this, the polarizing plate kit of the present invention can suppress the warpage of the liquid crystal panel even when the polarizing plate is exposed to a high temperature condition or a hot and humid environment. Further, aggregation failure of the second adhesive layer and the third adhesive layer can be suppressed. Further, even when the polarizing plate of the present invention is exposed to a high temperature condition or a hot and humid environment, the visibility of the polarizing plate is excellent, and light leakage of the polarizing plate is not generated.

As described above, when the polarizing plate kit of the present invention is disposed in a hot and humid environment and a high temperature environment, the amount of warpage is small, so that peeling from the touch panel and falling off of the backlight unit can be reduced or avoided. Moreover, it is associated with a reduction in display unevenness caused by warpage caused by exposure to a high temperature environment and a hot and humid environment.

[Industrial availability]

According to the present invention, it is possible to provide a polarizing plate set which suppresses warpage caused by, for example, shrinkage of a polarizing plate and a reflective polarizing plate. Furthermore, according to the present invention, it is possible to provide a polarizing plate set which is also suppressed in the aggregation failure of the adhesive layer of the glass substrate adhered to the liquid crystal cell.

10‧‧‧Back side polarizer

11‧‧‧Reflective polarizer

12‧‧‧1st adhesive layer

13‧‧‧1st polarizer

14‧‧‧1st protective film

15‧‧‧2nd adhesive layer

20‧‧‧ Front side polarizer

21‧‧‧3rd adhesive layer

22‧‧‧2nd polarizer

23‧‧‧2nd protective film

30‧‧‧Liquid Crystal Unit

dF, dR‧‧‧ thickness

Claims (4)

A polarizing plate set includes a back side polarizing plate disposed on one surface side of the liquid crystal cell and a front side polarizing plate disposed on the other surface side; and the back side polarizing plate includes a reflective polarizing plate and a first adhesive a layer, a first polarizer, a first protective film, and a second adhesive layer; the front polarizing plate includes a third adhesive layer, a second polarizer, and a second protective film; and the front polarizing plate (2) The thickness dF ( μm ) of the polarizer is subtracted from the thickness dR ( μm ) of the first polarizer of the back side polarizing plate, and the difference dF-dR is Δd ( μm ), 0 μm <Δd<5μm; the angle between the absorption axis of the second polarizer of the front side polarizing plate and the absorption axis of the first polarizer of the back side polarizing plate is 90°±1°. The polarizing plate kit according to claim 1, wherein an angle between an absorption axis of the first polarizer of the back side polarizing plate and a long side of the back side polarizing plate is 0°±0.5°. The polarizing plate kit according to claim 1 or 2, wherein the reflective polarizing plate has at least two thin films, and the refractive index anisotropy of the at least two thin films is different. A liquid crystal panel comprising a liquid crystal cell and a pair of polarizing plates disposed on both sides of the liquid crystal cell; the pair of polarizing plates being the polarizing plate set according to any one of claims 1 to 3. The liquid crystal panel is sequentially laminated with the second protective film and the second The polarizer, the third adhesive layer, the liquid crystal cell, the second adhesive layer, the first protective film, the first polarizer, the first adhesive layer, and the reflective polarizing plate.