TW201727291A - Polarizing plate - Google Patents

Abstract

An object of the present invention is to provide a polarizing plate in which warping due to shrinkage of polarizer and reflection type polarizing plate is suppressed. A further object of the present invention is to provide a polarizing plate in which cohesive failure of adhesive bonding to a glass panel of a liquid crystal cell is also suppressed. The polarizing plate of the present invention are laminated with a reflective polarizing plate, a first adhesive layer, a polarizer, a protective film, and a second adhesive layer in this order, wherein the interlayer thickness from the first adhesive layer side surface of the reflective polarizing plate to the surface of the second adhesive layer opposite to the protective film is 60 [mu]m or less, and the tensile elastic modulus of the protective film at 85 DEG C is 2500 MPa or less.

Description

Polarizer

The present invention relates to polarizing plates that can be used in a wide variety of optical applications.

With the demand for thinning of a polarizing plate, it is studied that a protective film made of a transparent resin which is usually bonded to both sides of a polarizing plate is disposed only on one side of the polarizing plate.

For example, Patent Document 1 discloses a liquid crystal panel in which a substrate of a liquid crystal cell, an adhesive layer, and a polarizer are laminated.

Moreover, in order to meet the thin film formation requirements of the polarizing plate, for example, a polarizing plate in which a first pressure-sensitive adhesive layer, a transparent protective film, a polarizing film, a second pressure-sensitive adhesive layer, and a transparent plastic substrate are sequentially laminated is being developed. (Patent Document 2).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-292939

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2010-39458

The polarizing plate having the above configuration is configured to be easily changed in the direction of the positive curl (the direction in which the end portion floats). For example, if the polarizing plate is exposed to high temperature conditions, particularly in the case of repeated exposure to high temperature and low temperature (hereinafter, referred to as a cold and hot cycle environment), shrinkage occurs in the polarizer and the reflective polarizing plate. Furthermore, due to such shrinkage, warpage occurs in the protective film. Further, the facing panel adhesive adhered to the glass panel is imparted under the condition that the force of warping toward the reflective polarizing plate and the adhesive force of the adhesive and the glass panel act in opposite directions, thereby causing adhesion to the panel. The glue produces agglutination damage. If agglomeration damage occurs to the panel adhesive, one part of the panel adhesive remains on the protective film, and the rest remains on the glass panel, which not only adversely affects the appearance, but also forms the liquid crystal display device at the end of the liquid crystal display device. Light leakage occurs and the quality of the display is reduced.

Therefore, it is desired to suppress the warpage of the protective film or the like due to the shrinkage of the polarizing plate and the reflective polarizing plate, and to further suppress the aggregation and damage of the panel adhesive. However, the structure of the conventional protective film using the cellulose resin film is The above problems are caused, but not enough.

Therefore, an object of the present invention is to provide a polarizing plate in which warpage caused by shrinkage of a polarizing plate and a reflective polarizing plate is suppressed. Still another object of the present invention is to provide a polarizing plate in which, for example, a liquid crystal cell is bonded to an adhesive layer of a glass panel and aggregation failure is also suppressed.

The invention includes the following.

[1] A polarizing plate in which a reflective polarizing plate and a first adhesive are sequentially laminated The interlaminar thickness of the agent layer, the polarizer, the protective film, and the second adhesive layer from the first adhesive layer side surface of the reflective polarizing plate to the surface of the second adhesive layer opposite to the protective film The protective elastic film has a tensile modulus of 2500 MPa or less at 85 ° C of 60 μm or less.

[2] The polarizing plate according to [1], wherein the protective film is a cyclic polyolefin resin film.

[3] The polarizing plate according to [1], wherein the protective film is an acrylic resin film.

[4] The polarizing plate according to any one of [1] to [3] wherein the thickness of the first adhesive layer is 20 μm or less.

[5] The polarizing plate according to any one of [1] to [4] wherein the second adhesive layer has a storage modulus at 80 ° C of 0.025 MPa or more and a thickness of 10 to 30 μm.

[6] The polarizing plate according to any one of [1] to [5] wherein the polarizer has a thickness of 10 μm or less.

[7] The polarizing plate according to any one of [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.

According to the present invention, a thin polarizing plate can be obtained. Further, even when the polarizing plate is exposed to high temperature conditions, particularly when exposed to a cold and hot cycle environment, the warpage of the polarizing plate can be suppressed, and the aggregation failure of the second adhesive layer can be further suppressed.

11‧‧‧ polarizer

12‧‧‧Reflective polarizer

13‧‧‧1st adhesive layer

22‧‧‧Protective film

23‧‧‧2nd adhesive layer

24‧‧‧Substrate

100‧‧‧Polar plate

D‧‧‧ interlayer thickness

Fig. 1 is a schematic cross-sectional view showing a preferred layer constitution in a polarizing plate of the present invention.

The second (A) diagram is a schematic cross-sectional view when warpage occurs in the positive curl direction in the polarizing plate. In the second (B) diagram, when the warp is generated in the positive curl direction in the polarizing plate, a microscope photograph of the polarizing plate is observed from the side of the reflective polarizing plate 12.

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

In the polarizing plate of the present invention, a reflective polarizing plate, a first adhesive layer, a polarizing plate, a protective film, and a second adhesive layer are laminated in this order from the first adhesive layer side surface of the reflective polarizing plate to the foregoing The interlayer thickness of the second adhesive layer on the surface opposite to the protective film is 60 μm or less, and the tensile modulus of the protective film at 85 ° C is 2,500 MPa or less.

The polarizing plate of the present invention is a polarizing plate 100 in which a reflective polarizing plate 12, a first adhesive layer 13, a polarizing plate 11, a protective film 22, and a second adhesive layer 23 are sequentially laminated as shown in Fig. 1 .

In the polarizing plate of the present invention, the interlayer thickness from the side of the first adhesive layer side of the reflective polarizing plate to the surface of the second adhesive layer opposite to the protective film (hereinafter, also referred to as "interlayer" The thickness "in the case of" is 60 μm or less, preferably 55 μm or less, and more preferably 47 μm or less. The thickness of the interlayer from the side of the first adhesive layer side of the reflective polarizing plate to the surface of the second adhesive layer opposite to the protective film The lower limit value is preferably 20 μm, more preferably 30 μm, and particularly preferably 40 μm.

The interlayer thickness is preferably from 20 to 60 μm, more preferably from 20 to 55 μm, still more preferably from 20 to 47 μm.

Here, the interlayer thickness corresponds to, for example, the interlayer thickness (D) in Fig. 1 . In this case, the interlayer thickness (D) corresponds to the total thickness of the first adhesive layer 13, the polarizer 11, the protective film 22, and the second adhesive layer 23.

Although not shown in Fig. 1, for example, a layer other than the above layer may be provided between the reflective polarizing plate 12 and the second adhesive layer 23 shown in Fig. 1. At this time, the thickness of the newly formed layer is also included in the interlayer thickness. Further, the polarizer 11 and the protective film 22 are usually bonded via an adhesive layer. The thickness of the adhesive layer can also be included in the interlayer thickness.

The measurement of the interlayer thickness of the polarizing plate in the present invention can be carried out by using a measuring method known in the art.

In the polarizing plate of the present invention, the tensile modulus at a temperature of 85 ° C is 2,500 MPa or less, and preferably the tensile modulus is 2,200 MPa or less, more preferably 1800 MPa or less.

The tensile modulus at 85 ° C of the protective film is usually 600 MPa or more, preferably 1400 MPa or more, more preferably 1500 MPa or more.

Further, it is preferred that the protective film has a tensile modulus at 85 ° C of 600 to 2500 MPa, more preferably 1400 to 2200 MPa, still more preferably 1500 to 1800 MPa.

In the polarizing plate of the present invention, from the side of the first adhesive layer side of the reflective polarizing plate to the second adhesive layer and the protective film The interlayer thickness to the surface on the opposite side is included in the intended range of the present case, and the tensile modulus at 85 ° C is included in the intended range of the case, whereby, for example, the polarizing plate is exposed to high temperature conditions. In particular, warpage of the reflective polarizing plate, the first adhesive layer, the polarizer, the protective film, and the second adhesive layer can be suppressed even when exposed to a cold and hot cycle environment. As a result, warpage of the entire polarizing plate can be suppressed.

Here, the exposure of the polarizing plate to a high temperature condition means that, for example, the polarizing plate is exposed to a temperature of 70 ° C to 95 ° C for 30 to 60 minutes.

Further, when the polarizing plate is exposed to a high temperature condition, at least one of the reflective polarizing plate, the first adhesive layer, the polarizing plate, the protective film, and the second adhesive layer faces in the positive crimping direction (the direction in which the end portion floats). It floats and generates warpage, and more specifically, it floats with the end part of the etc. toward a reflective polarizing plate, and a warp generate|occur|produces.

Further, when the polarizing plate of the present invention is exposed to high temperature conditions, when the polarizing plate is slightly warped, the reflective polarizing plate, the first adhesive layer, the polarizing film, the protective film, and the second adhesive layer become One and warped. Therefore, in the polarizing plate of the present invention, interlayer peeling is not normally caused in at least one of the reflective polarizing plate, the first adhesive layer, the polarizing plate, the protective film, and the second adhesive layer.

The warp caused by the polarizing plate causes warpage (floating) even in the second adhesive layer, and further causes aggregation failure of the adhesive constituting the second adhesive layer. When the aggregation failure occurs in the second adhesive layer, one part of the second adhesive remains on the protective film, and the remaining part of the second adhesive remains on the substrate bonded to the second adhesive, for example, Residual in the glass panel. This state is also referred to in this specification as a state in which a viscose pattern is produced. Further, the adhesive embossing in the present invention means, for example, a pattern of an adhesive constituting the second adhesive layer which remains in a continuous strip shape or a radial shape, such as a glass panel.

Such warpage can be evaluated in the present invention by measuring the amount of warpage or the like. For example, the amount of warpage is such that the second adhesive layer of the polarizing plate is bonded to the glass panel, and is allowed to stand for one cycle in an environment of -40 ° C for 30 minutes and then at 85 ° C for 30 minutes. The polarizing plate after 50 hours was measured for the relative height of the end portion bulging with respect to the horizontal plane of the in-plane center portion of the surface of the reflective polarizing plate opposite to the first adhesive layer.

The second (A) diagram is a schematic cross-sectional view when warpage occurs in the positive curl direction in the polarizing plate. For example, the amount of warpage of the polarizing plate after standing for 50 hours in the above-described cooling and heating cycle environment is as shown in the drawing, and the height of the entire end portion of the polarizing plate 100 and the polarizing plate 100 and the reflective polarizing light can be used. The first adhesive layer 13 of the plate 12 is calculated as the distance between the heights of the horizontal planes in the in-plane center portion on the opposite side. However, the modified form of each layer is an example and is not limited to this form. Fig. 2(A) shows an example in which the amount of shrinkage of the polarizer is larger than the amount of shrinkage of the reflective polarizer after standing for 50 hours in the above-described cold and heat cycle environment. Further, for example, depending on the type and thickness of the reflective polarizing plate, a modified form different from the second (A) drawing may be produced.

Preferably, the amount of warpage of the polarizing plate of the present invention is from 0.1 to 10 μm, more preferably from 0.1 to 8 μm. If the amount of warpage exceeds the above range, significant agglomeration damage occurs in the second adhesive layer. If the second adhesive layer is agglomerated Obviously, not only the appearance of the polarizing plate is adversely affected, but when the liquid crystal display device is incorporated, light leakage occurs at the end of the liquid crystal display device, and the quality of the display is lowered. For example, in the case of a polarizing plate having a length of 12 to 16 cm and a width of 6 to 10 cm, the amount of warpage is 0.1 to 10 μm, more preferably 0.1 to 8 μm.

On the other hand, for example, as shown in Fig. 2(A), the distance from the surface of the second adhesive layer side of the glass panel to the end of the floating polarizing plate can be measured, that is, the measurement remains on the protective film. 2 The distance from the surface end of the glass panel side of the adhesive layer to the end of the floating polarizing plate (hereinafter also referred to as "floating amount"). At this time, the preferable floating amount is 0.1 to 10 μm, more preferably 0.1 to 8 μm. When the amount of floating exceeds the above range, significant agglomeration damage occurs in the second adhesive layer. When the aggregation failure of the second adhesive layer is remarkable, not only the appearance of the polarizing plate is adversely affected, but when incorporated in the liquid crystal display device, light leakage occurs at the end portion of the liquid crystal display device, and the quality of the display is lowered.

Further, in the case of a polarizing plate having a length of 12 to 16 cm and a width of 6 to 10 cm, the amount of floating is preferably from 0.1 to 10 μm, more preferably from 0.1 to 8 μm.

Further, the relationship between the value of the "warpage amount" and the value of the "floating amount" is not particularly limited as long as each value is within the above range. For example, when the value of "warpage amount" is the above maximum value, the value of "floating amount" may be the above minimum value. The value of "warping amount" and the value of "floating amount" may be similar.

In the present invention, the "viscosity length" is obtained by observing the polarizing plate from the side of the reflective polarizing plate and measuring the length of the observed adhesive tape. Specifically, the distance between the straight line formed by joining the lower ends of the convex portions in the observed adhesive tape and the apex of the convex portion is measured, and the measurement is performed. The maximum value of the obtained measurement result is set to "viscosity length" in plural times.

For example, when the polarizing plate is viewed from the side of the reflective polarizing plate, as shown in Fig. 2(B), the adhesive pattern is observed, and the adhesive is calculated from the lower end of the convex portion and the apex of the convex portion in the adhesive pattern. The length of the grain.

The length of the viscose can be determined by methods well known in the art. The length of the adhesive tape is preferably less than 100 μm, and more preferably less than 50 μm. By including the length of the adhesive tape in such a range, it does not adversely affect the visibility of the polarizing plate. On the other hand, if the length of the adhesive tape is 100 μm or more, the visibility of the polarizing plate is adversely affected, and the appearance of the polarizing plate is also deteriorated.

In a preferred embodiment, when the amount of warpage is 0.1 to 10 μm, the length of the adhesive tape is 5 to 90 μm, more preferably 5.0 to 50 μm.

In another preferred embodiment, when the floating amount is 5.0 μm, the length of the adhesive tape is 5 to 90 μm, more preferably 5.0 to 50 μm.

In the present invention, the "adhesive offset distance" means the moving distance of the end portion of the polarizing plate due to the contraction of the polarizing plate. For example, the offset distance of the adhesive may be the end of the polarizing plate from the end of the polarizing plate immediately after bonding to the substrate such as a glass panel to the end of the polarizing plate after standing for 240 hours in an environment of 85 ° C. Moving distance. As shown in the second (B), when the polarizing plate is viewed from above, the offset distance of the adhesive can be expressed from the end of the polarizing plate immediately after bonding to a substrate such as a glass panel to the end of the polarizing plate after shrinking. The contraction distance so far. Further, the end portion of the polarizing plate shown in Fig. 2(B) means the end portion of the reflective polarizing plate 12. Moreover, the offset distance of the adhesive will be due to the second adhesive used, The combination of polarizers and the like changes.

[Reflective polarizer]

The reflective polarizing plate is also called a brightness enhancing film, and a polarizing conversion element having a function of separating emitted light from a light source (backlight) into a transmitted polarized light and a reflected polarized light or a scattered polarized light can be used. As described above, by arranging the reflective polarizing plate above the polarizer, the retroreflective light of the reflected polarized light or the scattered polarized light can improve the emission efficiency of the linearly polarized light emitted from the polarizer. The reflective polarizing plate is attached to the first adhesive layer to be laminated.

The reflective polarizing plate may be, for example, an anisotropic reflective polarizer. An example of an anisotropic reflective polarizer is an anisotropic multilayer film that transmits a linearly polarized light in one vibration direction and a linearly polarized light in a direction of vibration of the other, and a specific example is DBEF made by 3M (Japanese special open flat) 4-268505, 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 extended. Therefore, such a reflective polarizing plate has a film of at least two layers, and at least two layers of the film which are stretched are different in refractive index anisotropy.

Another example of the anisotropic reflective polarizer is a complex of a cholesteric liquid crystal layer and a λ/4 plate, and a specific example thereof is PCF manufactured by Nitto Denko Corporation (Japanese Patent Laid-Open Publication No. Hei 11-231130, etc.). Another example of the anisotropic reflective polarizer is a reflective grating polarizer, and a specific example thereof is a metal lattice reflective polarizer that imparts fine processing to a metal and a reflective polarized light in a visible light region (US Patent No. 6288840, etc.), Metal microparticles are added to a polymer matrix and extended film (Japanese Patent Laid-Open No. 8-184701) Bulletin).

The surface of the reflective polarizing plate opposite to the first adhesive layer may be provided with 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. 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 film formation of the polarizing plate.

In the polarizing plate of the present invention, the surface of the reflective polarizing plate on the side of the first adhesive layer can be subjected to surface activation treatment. This surface activation treatment is performed before the bonding of the reflective polarizing plate and the first adhesive layer. Thereby, a polarizing plate which is less likely to be peeled off between the first adhesive layer and the reflective polarizing plate and which is excellent in wet heat durability in a hot and humid environment can be obtained.

The surface activation treatment may be a hydrophilization treatment of the surface, and may be a dry treatment or a wet treatment. The dry treatment may, for example, be a corona treatment, a plasma treatment, a discharge treatment of a corona discharge treatment, a flame treatment, an ozone treatment, a UV ozone treatment, an ultraviolet radiation treatment, an ionizing active ray treatment using an electron beam treatment, or the like. The wet treatment can be exemplified by, for example, ultrasonic treatment using a solvent such as water and acetone, alkali treatment, anchor treatment, and the like. These treatments may be carried out singly 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 humid heat environment and the productivity of the polarizing plate. By the surface activation treatment, the thickness of the reflective polarizing plate is thin, and even if it is, for example, 30 μm or less, the first adhesive can be effectively suppressed in a hot and humid environment. Peeling between the layer and the reflective polarizer. Further, the surface of the first adhesive layer on the side of the brightness-reflective polarizing plate may be subjected to a surface activation treatment.

[1st adhesive layer]

The layer between the polarizer and the reflective polarizer in the first adhesive layer. The first adhesive layer is typically laminated directly on the polarizer in such a manner that the polarizer is in contact with the first adhesive layer.

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

The acrylic base material polymer may suitably be used, for example, such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, or 2-ethylhexyl (meth)acrylate. The (meth) acrylate type base material polymer and the two or more types of copolymerization base material polymers using such (meth) acrylate. The base polymer is preferably a copolymer of a polar monomer. The polar monomer may, for example, be (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, (meth)acrylic acid N,N. a monomer having a carboxyl group, a hydroxyl group, a decylamino group, an amine group, an epoxy group or the like of dimethylaminoethyl ester or glycidyl (meth)acrylate.

The adhesive composition usually contains a crosslinking agent. The crosslinking agent is a metal ion having a valence of 2 or more, and is exemplified by forming a carboxylic acid with a carboxyl group. a metal salt; a polyamine compound and forming a guanamine bond with a carboxyl group; a polyepoxide, a polyol, and an ester bond formed between the carboxyl group; a polyisocyanate compound, and a carboxyl group The formation of a guanamine bond between the two. Among them, a polyisocyanate compound is preferred.

The active energy ray-curable adhesive composition has a property of being cured by irradiation with an active energy ray such as an ultraviolet ray or an electron ray, and is adhesively adhered to the film even before the active energy ray irradiation. The body has an adhesive composition which can be hardened by irradiation with an active energy ray and adjusts the adhesion force. The active energy ray-curable adhesive composition is preferably an ultraviolet curing type. The active energy ray-curable adhesive composition may further contain an active energy ray-polymerizable compound in addition to the base polymer or the crosslinking agent. Further, depending on the needs, there are cases in which a photopolymerization initiator, a photosensitizer, and the like are contained.

The adhesive composition may contain fine particles for imparting light scattering properties; beads; a resin other than the base polymer; a tackifier; 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 adhesive composition onto 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 formed adhesive layer can be irradiated with an active energy ray to form a desired cured product.

The first adhesive layer is preferably one having a storage modulus of from 0.15 to 1.2 MPa in a temperature range of from 23 to 80 °C. Thereby, it is easy to generate the shrinkage of the polarizer in the heat-resistant and cold-heat cycle environment. The dimensional change can improve the durability of the polarizing plate. Further, when a liquid crystal display device (for example, a liquid crystal display device for a small-sized portable terminal) equipped with a polarizing plate is placed in a heat-resistant and cold-heat cycle environment, the variation of the polarizing plate is suppressed, so that the reliability of the liquid crystal display device can be improved. .

The phrase "having a storage elastic modulus of 0.15 to 1.2 MPa in a temperature range of 23 to 80 ° C" means that the storage elastic modulus is a value within the above range at any temperature in the range. The storage modulus is generally gradually decreased as the temperature rises. Therefore, as long as the storage modulus at 23 ° C and 80 ° C falls within the above range, it is considered that the storage modulus in the above range is exhibited in the temperature of the range. The storage elastic modulus of the first adhesive layer can be measured by using a commercially available viscoelasticity measuring device, and can be measured, for example, by using a viscoelasticity measuring device "DYNAMIC ANALYZER RDA II" manufactured by REOMETERIC Co., Ltd. shown in the later-exemplified Examples.

The method for adjusting the storage modulus to the above range is to add an oligomer to form an active energy ray-curable adhesive composition in an adhesive composition containing a base polymer and a crosslinking agent. A fine ultraviolet curable adhesive composition), specifically, an oligomer of a urethane acrylate type is mentioned as this oligomer. 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, more 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 set so that the thickness of the interlayer is within a predetermined range Adjustment.

[Polarizer]

The polarizer has an absorption type polarizer that absorbs linearly polarized light having a vibration plane parallel to the absorption axis and transmits a linearly polarized light having a vibration plane orthogonal to the absorption axis (parallel to the transmission axis), and can be suitably used. A polarizing film in which a dichroic dye is oriented is adsorbed on the polyvinyl alcohol resin film. 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 with a dichroic dye to adsorb the dichroic dye. 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 a boric acid aqueous solution and then washing with water.

As the polyvinyl alcohol-based resin, those obtained by saponifying a polyvinyl acetate-based resin can be used. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate, in addition to the polyethyl acetate of the homopolymer of vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and amides having ammonium groups.

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 can be modified, and for example, an aldehyde-modified polyvinyl formaldehyde or a polyvinyl acetal can 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 made of such a polyvinyl alcohol-based resin can be used as a film of a polarizer (polarizing film). The method for forming a film of a polyvinyl alcohol-based resin is not particularly limited, and a known method can be employed. The thickness of the polyvinyl alcohol-based germplasm membrane is not particularly limited. However, in order to make the thickness of the polarizer 10 μm or less, it is preferable to use about 5 to 35 μm. More preferably, it is 20 μm or less.

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

In the case of uniaxial stretching, it can be extended in a single axis between rolls having different rotational speeds, or can be extended in a single axis using a heat roller. Further, the uniaxial stretching may be a dry stretching in which stretching is carried out in the air, or may be a wet stretching in which a 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.

For the method of dyeing a polyvinyl alcohol-based resin film as 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.

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

The boric acid treatment after dyeing with a dichroic dye is usually carried out by immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. When iodine is used as the dichroic dye, it is preferred that the aqueous solution containing boric acid contains potassium iodide.

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

After washing with water, it is subjected to a drying treatment 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, more preferably 10 μm or less. When the thickness of the polarizer is 15 μm or less, it is advantageous for thinning of the polarizing plate and the liquid crystal display device. The thickness of the polarizer is usually 4 μm or more. Further, the thickness of the polarizer can be appropriately adjusted so that the thickness of the interlayer is within a predetermined range.

[protective film]

The protective film is laminated on the film on the opposite side of the polarizer from the first adhesive layer. The protective film may be a thermoplastic resin having light transmissivity (preferably optically transparent), for example, a chain polyolefin resin (such as a polypropylene resin) or a cyclic polyolefin resin (a decene resin). a polyolefin resin; for example, a cellulose resin such as triethyl fluorenyl cellulose or diethyl hydrazine cellulose; a 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 Resin; polyvinyl acetate resin; polyvinylidene chloride resin; polyamine resin; polyacetal resin; modified polyphenylene ether resin; polyfluorene resin; polyether oxime resin; A film composed of an aromatic acid ester-based resin, a polyamidoximine-based resin, or a polyimine-based resin. Among them, a polyolefin resin or an acrylic resin is preferably used, and a cyclic polyolefin resin is preferably used.

The chain polyolefin resin is a homopolymer of a chain olefin such as a polyethylene resin or a polypropylene resin, and a copolymer containing two or more kinds of chain olefins is also mentioned.

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 resin include a ring-opening (co)polymer of a cyclic olefin and an addition of a cyclic olefin. a copolymer of a polymer, a cyclic olefin and a chain olefin such as ethylene or propylene (representative random copolymer), and a graft polymer modified with an unsaturated carboxylic acid or a derivative thereof, and Such as hydrides and the like. Among them, a norbornene-based resin which uses a norbornene-based monomer such as norbornene and a polycyclic norbornene-based monomer as a cyclic olefin is preferable. In a preferred embodiment, the protective film of the present invention comprises a cyclic polyolefin resin.

The term "cellulosic resin" means a part or all of hydrogen atoms in the hydroxyl group of the cellulose obtained from the raw material cellulose such as cotton linter or wood pulp (broadwood pulp, conifer pulp), and the like. a cellulose organic acid ester substituted with a base and/or a butyl group or an organic acid ester of a mixed cellulose. For example, it is composed of cellulose acetate, propionate, butyrate, and a mixed ester thereof.

A preferable specific example of the acrylic resin film is, for example, a film containing a methyl methacrylate resin. The methyl methacrylate-based resin is 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 a monofunctional monomer having methyl methacrylate as a main component and a polyfunctional monomer which is optionally used in combination with a radical polymerization initiator and as needed. The chain transfer agent used is obtained by carrying out polymerization in the presence of a chain transfer agent.

Monofunctional monomer copolymerizable with methyl methacrylate For example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and methacrylic acid Methyl acrylates other than methyl methacrylate such as 2-hydroxyethyl ester; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethyl acrylate Acrylates such as hexyl ester and 2-hydroxyethyl acrylate; methyl 2-(hydroxymethyl)acrylate, methyl 3-(hydroxyethyl)acrylate, ethyl 2-(hydroxymethyl)acrylate, and 2-( Hydroxy acrylates such as hydroxymethyl)butyl acrylate; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene; substituted styrene such as vinyl toluene and α-methylstyrene Unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated anhydrides such as maleic anhydride and citraconic anhydride; and unsaturated quinones such as phenylmaleimide and cyclohexylmaleimide Classes, etc. Such a single system may be used alone or in combination of two or more.

The polyfunctional monomer copolymerizable with methyl methacrylate may, for example, be ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, or triethylene glycol di(a). Acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, and tetrakis(ethylene glycol)(meth)acrylate, etc. The two terminal hydroxyl groups of the polymer are esterified with acrylic acid or methacrylic acid; the two terminal hydroxyl groups of propylene glycol or its oligomer are esterified with acrylic acid or methacrylic acid; neopentyl glycol di( a hydroxyl group of a divalent alcohol such as methyl acrylate, hexanediol di(meth) acrylate or butanediol di(meth) acrylate, which is esterified with acrylic acid or methacrylic acid; A, bisphenol A epoxy The alkane adduct or the terminal hydroxyl group of the halogen substitute is esterified with acrylic acid or methacrylic acid; the polyol such as trimethylolpropane and neopentyl alcohol is esterified with acrylic acid or methacrylic acid. The cyclized, and the terminal hydroxyl group is added to form an epoxy group of glycidyl acrylate or glycidyl methacrylate; succinic acid, adipic acid, terephthalic acid, phthalic acid And a cyclopentadienic acid such as a halogen-substituted product such as a halogen-substituted product or an alkylene oxide adduct thereof or the like, or a ring-opening addition of an epoxy group of glycidyl acrylate or glycidyl methacrylate; (methyl); An aryl acrylate; a diaryl compound such as divinylbenzene or 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 system may, for example, be a polymer chain deco-methanol condensation reaction of a methyl ester group of methyl acrylate with a hydroxyl group of methyl 2-(hydroxymethyl) acrylate, and a carboxyl group and 2-(hydroxymethyl group) of acrylic acid. A polymer chain internal dehydration condensation reaction of a hydroxyl group of methyl acrylate.

The phase difference of the protective film is also used to control the liquid crystal display device at an appropriate value. For example, in a liquid crystal display device of an in-plane switching (IPS, In-Plane Switching) mode, it is preferable to use a film having a substantially phase difference value of zero. The phase difference value is substantially zero, which means that the in-plane retardation value at a wavelength of 590 nm is 10 nm or less, the absolute value of the retardation value in the thickness direction at a wavelength of 590 nm is 10 nm or less, and the retardation value in the thickness direction at a wavelength of 480 to 750 nm. The absolute value is 15 nm or less.

The protective film may also be stretched and/or shrunk by the mode of the liquid crystal display device to impart an appropriate 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, handleability and the like. If the thickness is within this range, the polarizer can be mechanically protected, and the polarizer does not shrink even when exposed to a hot and humid environment, maintaining the optical properties of stability. 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 the adhesive layer. As the adhesive for forming the adhesive layer, a water-based adhesive or an active energy ray-curable adhesive can be used.

The water-based adhesive agent may, for example, be an adhesive containing a polyvinyl alcohol-based resin aqueous solution or an aqueous two-liquid urethane-based emulsion adhesive. Among them, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is preferably used. The polyvinyl alcohol-based resin may be a copolymer of vinyl acetate and vinyl acetate in addition to a vinyl alcohol homopolymer obtained by saponifying a polyvinyl acetate homopolymer of vinyl acetate. The copolymer of the other monomer is subjected to a saponification treatment to obtain a modified polyvinyl alcohol polymer such as a polyvinyl alcohol-based copolymer or a part of a hydroxyl group thereof. 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.

When a water-based adhesive is used, it is preferred to apply a polarizing film and a protective film after removing the water contained in the water-based adhesive. Its drying step. After the drying step, a ripening step of aging at a temperature of, for example, about 20 to 45 ° C may be provided.

The active energy ray-curable adhesive 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. Resin resin and photoreactive cross-linking agent, etc. The polymerizable compound is, for example, a photocurable epoxy monomer, a photocurable acrylic monomer, a photocurable urethane monomer, and a photopolymerizable monomer. Oligomers of the body. The photopolymerization initiator may be one which contains an active species such as a neutral radical, an anionic radical, or a cationic radical by irradiation with an active energy ray such as ultraviolet rays. As the active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator, those containing a photocurable epoxy monomer and a photocationic polymerization initiator can be suitably used.

When the active energy ray-curable adhesive is used, after the polarizer is bonded to the protective film, the drying step is performed as needed, and then the active energy ray is irradiated to harden the active energy ray-curable adhesive. The light source of the active energy ray is not particularly limited, but is preferably an ultraviolet ray having a light-emitting distribution at 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, or a black light can be used. Lights, microwaves, mercury lamps, metal halide lamps, etc.

When the polarizer and the protective film are attached, the bonding surface of at least one of them may be subjected to saponification treatment, corona treatment, plasma treatment Wait.

[2nd adhesive layer]

The adhesive for forming the second adhesive layer may be any conventionally known, and may have a degree of adhesion without causing peeling or the like in an environment where the polarizing plate is exposed to a high temperature environment, a hot and humid environment, or a high temperature and a low temperature. Yes. Specifically, for example, an acrylic adhesive, a polyoxygen adhesive, a rubber adhesive, and the like are preferable, and an acrylic adhesive is particularly preferable in terms of transparency, weather resistance, heat resistance, and workability.

Further, the same adhesive layer may be used for the first adhesive layer and the second adhesive layer, and different kinds of adhesives may be used.

In a preferred embodiment, the second adhesive layer is formed of an acrylic adhesive.

In the adhesive, an adhesive, a plasticizer, a glass fiber, a glass bead, a metal powder, a filler containing other inorganic powder, a pigment, a colorant, a filler, an antioxidant, and an ultraviolet absorption may be appropriately formulated as needed. Various additives such as an agent, an antistatic agent, and a decane coupling agent.

The adhesive layer is usually formed by applying an adhesive on a release sheet with a solution of an adhesive and drying. The coating on the release sheet may be, for example, a roll coating method such as reverse coating or gravure coating, a spin coating method, a screen coating method, a fountain coating method, a dipping method, or the like. Spraying method, etc. A release sheet provided with an adhesive layer can be applied by a method of transferring the same. The thickness of the adhesive layer is usually from about 3 to 30 μm, preferably from 10 to 30 μm, more preferably from 10 to 25 μm. In a preferred implementation In the aspect, the second adhesive layer has such a thickness that the destruction of the polarizing plate can be suppressed, and when incorporated in the liquid crystal display device, light leakage at the end portion of the liquid crystal display device can be suppressed. Further, the thickness of the second adhesive layer can be appropriately adjusted so that the thickness of the interlayer is within a predetermined range.

The storage elastic modulus of the second adhesive layer at 80 ° C is preferably 0.025 MPa or more, more preferably 0.07 MPa or more. If the storage elastic modulus of the adhesive layer is less than 0.025 MPa, aggregation failure of the second adhesive layer occurs, and if the agglutination damage is remarkable, not only the appearance of the polarizing plate is adversely affected, but also when incorporated in the liquid crystal display device, Light leakage occurs at the end of the liquid crystal display device, which has an adverse effect on the display. Preferably, the second adhesive layer has a storage modulus at 80 ° C of 1.1 MPa or less, preferably 0.9 MPa or less. When the storage elastic modulus of the adhesive layer at 80 ° C exceeds 1.1 MPa, the heat resistance durability of the second adhesive layer to the glass or the panel is deteriorated, and it is easy to generate bubbles between the layers.

Until the second adhesive layer is bonded to other members, a separation film may be provided to protect the surface. For example, a film made of a transparent resin such as polyethylene terephthalate with a polyfluorene-based release agent can be used as a processor.

[Method of Manufacturing Polarizing Plate]

The polarizing plate of the present invention can be produced, for example, by the step of applying a surface activation treatment on the surface of the first polarizing layer on the side of the reflective polarizing plate, and the surface subjected to the surface activation treatment. The step of laminating the first adhesive layer.

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

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

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

[Liquid Crystal Display Device]

The polarizing plate of the present invention can be suitably applied to a liquid crystal display device. The liquid crystal display device includes a liquid crystal cell and a polarizing plate of the present invention bonded to the surface thereof. The bonding of the polarizing plate of the liquid crystal cell can be performed via the second adhesive layer. The polarizing plate of the present invention can be generally used as a polarizing plate disposed on the backlight side of the liquid crystal cell. The driving method of the liquid crystal cell can be any conventionally known method, but it is preferably an IPS mode. The liquid crystal display device using the polarizing plate of the present invention is excellent in wet heat durability.

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

[Examples]

Hereinafter, the present invention will be specifically described by showing examples, but the present invention is not limited by the examples. In the examples, the % and the parts of the content or the amount used are based on weight unless otherwise specified.

Further, the thickness of the film, the tensile modulus, and the storage modulus of the adhesive layer were measured in accordance with the following.

(1) Thickness

The measurement was carried out using a Digital Micrometer "MH-15M" manufactured by Nikon Corporation.

(2) Tensile modulus

A test piece of 2.5 cm width × 10 cm length was cut out from the film. Then, the upper and lower jigs of the test piece were clamped by a tensile tester [AUTOGRAPH AG-1S test machine manufactured by Shimadzu Corporation], and the ends of the test piece were clamped at a distance of 5 cm, at 85 ° C. The tensile modulus was measured at a tensile speed of 1 mm/min, and the tensile modulus at 85 ° C was calculated from the slope of the initial straight line in the obtained stress-strain curve. This measurement was performed in the "film transfer direction (MD direction), and the calculated value was used as the tensile modulus of the film.

(3) Storage elastic rate

The storage elastic modulus G' of the adhesive layer was measured in accordance with the following (I) to (III).

(I) Two samples each of 25 ± 1 mg were taken out from the adhesive layer, and each of them was formed into a substantially spherical shape.

(II) The obtained substantially spherical sample is attached to the upper surface of the type I jig, and the upper and lower sides are sandwiched by the L-shaped jig. The composition of the test sample is an L-shaped jig/adhesive/I-type jig/adhesive/L-type jig.

(III) The storage elastic modulus G' of the sample prepared in this manner was measured using a dynamic viscoelasticity measuring device "DVA-220" manufactured by IT Measurement and Control Co., Ltd. under the conditions of a temperature of 80 ° C, a frequency of 1 Hz, and an initial strain of 1 N. .

[Production of polarizer]

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

[Example of preparation of the first adhesive layer]

The organic solvent solution containing the composition shown in Table 1 is dried to become In a predetermined thickness, a release coating surface of a polyethylene terephthalate-containing separation membrane having a thickness of 38 μm which was subjected to a release treatment was applied by a die coater, and dried to obtain a separation membrane. Adhesive layer. The thickness of the first adhesive layer in each of the examples and the comparative examples and the storage modulus at 80 ° C are shown in Table 1.

[Example of preparation of the second adhesive layer]

The organic solvent solution containing the composition shown in Table 2 was applied to a separation film containing polyethylene terephthalate having a thickness of 38 μm which was subjected to release treatment by a die coater to a predetermined thickness after drying. The surface is treated by release and allowed to dry to obtain an adhesive layer with a separation membrane. The thickness of the first adhesive layer in each of the examples and the comparative examples and the storage modulus at 80 ° C are shown in Table 2.

[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.

COP-1: a cycloolefin-based protective film (manufactured by Zeon Co., Ltd.), a thickness of 13 μm, an in-plane retardation value at a wavelength of 590 nm = 3.46 nm, and a tensile modulus at 80 ° C = 1764 MPa.

COP-2: a cycloolefin-based protective film (manufactured by JSR AG) having a thickness of 15 μm, an in-plane retardation value at a wavelength of 590 nm = 2.44 nm, and a tensile modulus at 80 ° C = 1601 MPa.

Zero TAC: a triethylenesulfonyl cellulose-based protective film (manufactured by Konica Minolta Co., Ltd.) having a thickness of 20 μm, an in-plane retardation value at a wavelength of 590 nm = (1.37) nm, and a tensile modulus at 80 ° C = 3956 MPa.

Acrylic acid-1: (manufactured by Okura Kogyo Co., Ltd.) heat-resistant acrylic protective film, thickness 21 μm, in-plane retardation at a wavelength of 590 nm = -1.6 nm, and tensile modulus at 80 ° C = 2025 MPa.

Acrylic acid-2: (manufactured by Sumitomo Chemical Co., Ltd.) A general-purpose acrylic protective film containing a rubber particle, a thickness of 21 μm, an in-plane retardation value at a wavelength of 590 nm = -1.6 nm, and a tensile modulus at 80 ° C = 820 MPa.

"Modulation of water-based adhesives"

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. Water-soluble polyamine epoxy resin [Sumirez Resin 650 (30)", manufactured by Tadaoka Chemical Industry Co., Ltd., solid content concentration: 30% by weight] in an amount of 1.5 parts by weight based on 100 parts by weight of water. The ratios were mixed to obtain a water-based adhesive.

100 parts of bis(3,4-epoxycyclohexylmethyl)adipate, 25 parts of hydrogenated bisphenol A diglycidyl ether and 4,4'-bis(diphenyl) as photocationic polymerization initiator Diethyl thiodithio)diphenyl sulfide bis(hexafluorophosphate) (50% propylene carbonate solution) 2.2 parts (amount of active ingredient) are mixed, and then defoamed to prepare a curable epoxy resin composition An active energy ray-curable adhesive.

[Production Example of Polarizing Plate]

The case of using a water based adhesive.

First, the protective film 22 is bonded to one surface of the polarizer 11 by using the above-described water-based adhesive (thickness: 10 to 100 nm). Before the bonding, the bonding surface of the protective film and the polarizer was subjected to a corona treatment of 0.8 kJ/m ² . Thereafter, it was dried at 80 ° C for 5 minutes and cooked at 40 ° C for 72 hours.

The case of using an active energy ray hardenable adhesive.

The protective film 22 is bonded to one surface of the polarizer 11 by using the above-described active energy ray-curable adhesive. Before the bonding, the bonding surface of the protective film and the polarizer was subjected to a corona treatment of 0.8 kJ/m ² . After the polarizer 11 and the protective film 22 were bonded, ultraviolet rays were irradiated by an ultraviolet irradiation device (light: Fusion D lamp, cumulative light amount: 1000 m J/cm ² ), and left at room temperature for 1 hour.

Then, the first adhesive layer is bonded to the surface of the polarizer opposite to the surface on which the protective film is laminated. Before the bonding, corona treatment of 10.8 kJ/m ^{2 was performed on} both the bonding surface of the polarizer and the bonding surface of the first adhesive layer.

Then, the second adhesive layer is bonded to the outer surface of the protective film. Before the bonding, a corona treatment of 0.8 kJ/m ^{2 was} applied to both the bonding surface of the protective film and the bonding surface of the second adhesive layer.

Finally, the separation film of the first adhesive layer was peeled off, and a corona treatment of 0.8 kJ/m ^{2 was applied to} one surface of the reflective polarizing plate, and then the reflective polarizing plate was attached to the first adhesive side with the corona-treated surface side. On the outside of the agent layer, a polarizing plate is obtained.

The configuration of the polarizing plate obtained in this manner is shown in Table 3 (Example) and Table 4 (Comparative Example).

Further, the physical properties of each of the obtained polarizing plates were evaluated in accordance with the following description.

[Measurement of interlayer thickness]

The interlayer thickness from the side of the first adhesive layer side of the reflective polarizing plate to the surface of the second adhesive layer opposite to the protective film was calculated. The interlayer thicknesses of the examples and the comparative examples are shown in Table 3 (Example) and Table 4 (Comparative Example). Moreover, the measurement of the thickness of each layer was measured using the Digital micrometer "MH-15M" by Nikon Corporation. Further, the interlayer thickness was calculated by totaling the thickness of each layer.

[Measurement of warpage amount]

With respect to the polarizing plate produced above, the amount of warpage was measured in the following manner. First, in the polarizing plate to be produced, the surface of the second adhesive layer opposite to the protective film is bonded to glass (manufactured by Corning Incorporated, model: EAGLE XG ^{(registered trademark)} ), and it is in a hot and cold cycle (-40 ° C). It was allowed to stand for 50 hours in an environment of 30 minutes and then at 30 ° C for 1 minute at 85 ° C. With respect to the polarizing plate that generates warpage, the value of the height from the height of the ridge at the end portion minus the central portion in the plane of the polarizing plate was measured as the amount of warpage. The measurement of the amount of warpage was carried out by using (manufactured by SENSOFAR Co., Ltd., model: Plu neox 3D Optical Profiler), and the warpage height of the end portion was measured three times, and the average value of the warpage amount was shown in Table 3 (Example) and Table 4 ( Comparative example).

[Determination of the length of the adhesive tape]

In the polarizing plate used for the measurement of the amount of warpage, if warpage occurs, aggregation damage occurs in the second adhesive layer, and the second protective film is formed. On the side of the adhesive layer and the second adhesive layer side of the glass panel, the second adhesive is broken, and the second adhesive remains on the protective film and the glass panel.

Here, the second adhesive remaining on the surface of the glass panel exists in a continuous strip shape or a radial shape. The length of the second adhesive remaining in the glass panel, that is, the length of the adhesive pattern, is a magnification of 500x (manufactured by KEYENCE Corporation, model: VHX-1000), and is measured, for example, in FIG. 2(A) and (B) The length of the adhesive pattern shown. The lengths of the three adhesive stripes were measured, and the maximum value obtained was used as the adhesive tape length of each of the examples and the comparative examples. The results are shown in Table 3 (Examples) and Table 4 (Comparative Examples).

[Appearance evaluation]

Regarding the polarizing plate used for the measurement of the above warpage amount, the appearance of the polarizing plate was observed. The evaluation is based on the following benchmarks. The visibility of the adhesive pattern was confirmed by a magnifying glass, and then the light leakage of the polarizing plate was observed in an overlapping state with another glass in which the polarizing plate was bonded to become a crossed nicol.

◎: The visibility of the polarizing plate was extremely good, and no light leakage of the polarizing plate was observed.

○: The visibility of the polarizing plate was good, and no light leakage of the polarizing plate was observed.

△: The visibility of the polarizing plate was poor, or the light leakage of the polarizing plate was observed.

×: The visibility of the polarizing plate was poor, and light leakage of the polarizing plate was observed.

From such a result, the polarizing plate of the present invention can obtain a thin polarizing plate. Moreover, even if the polarizing plate is exposed to high temperature conditions, When exposed to a cold and hot cycle environment, the warpage of the polarizing plate can be suppressed, and the aggregation failure of the second adhesive layer can be further suppressed. Moreover, even if the polarizing plate of the present invention is exposed to high temperature conditions, especially when exposed to a cold and heat cycle environment, the visibility of the polarizing plate is extremely good, and light leakage of the polarizing plate is not generated.

[Industrial availability]

According to the present invention, it is possible to provide a polarizing plate which suppresses warpage caused by shrinkage of a polarizing plate and a reflective polarizing plate. Further, according to the present invention, it is possible to provide a polarizing plate which also suppresses aggregation failure of an adhesive layer adhered to a glass panel of a liquid crystal panel.

11‧‧‧ polarizer

12‧‧‧Reflective polarizer

13‧‧‧1st adhesive layer

22‧‧‧Protective film

23‧‧‧2nd adhesive layer

100‧‧‧Polar plate

D‧‧‧ interlayer thickness

Claims (7)

A polarizing plate in which a reflective polarizing plate, a first adhesive layer, a polarizing film, a protective film, and a second adhesive layer are laminated, from the side of the first adhesive layer side of the reflective polarizing plate to the first The interlayer thickness of the adhesive layer on the opposite side to the protective film is 60 μm or less, and the tensile modulus of the protective film at 85 ° C is 2500 MPa or less. The polarizing plate according to claim 1, wherein the protective film is a cyclic polyolefin resin film. The polarizing plate according to claim 1, wherein the protective film is an acrylic resin film. The polarizing plate according to any one of claims 1 to 3, wherein the thickness of the first adhesive layer is 20 μm or less. The polarizing plate according to any one of claims 1 to 4, wherein the second adhesive layer has a storage modulus at 80 ° C of 0.025 MPa or more and a thickness of 10 to 30 μm. The polarizing plate according to any one of claims 1 to 5, wherein the polarizer has a thickness of 10 μm or less. The polarizing plate according to any one of claims 1 to 6, 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.