TW201804222A - Polarizing plate set - Google Patents

Abstract

The objective of present invention is to provide a polarizing plate set, which has a small amount of curvature when disposed in a moist and hot, as well as high temperature environment; and it is capable of reducing display unevenness caused by curvature. The polarizing plate set of the present invention comprises a front side polarizing plate disposed on one side of a liquid crystal cell, and a rear side polarizing plate disposed on the other side; wherein the front side polarizing plate has a first protective film and a first polarizer, and the first protective film and the first polarizer are sequentially laminated from the side far from the liquid crystal cell; the first protective film has a slow axis, and has a shrinkage ratio of 0.1 to 1.0% in the slow axis direction when left to stand in an environment of 85 DEG C, humidity of 5% for 100 hours, and the elastic modulus in the slow axis direction at 85 DEG C is 1000 MPa to 3000 MPa; the angle formed by the slow axis of the first protective film and the absorption axis of the first polarizer is larger than 60 DEG and smaller than 90 DEG; the back side polarizing plate has a second polarizer.

Description

Polarizer set

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

A 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 polarizing plate 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 thickness of the liquid crystal panel by the thickness relationship between the polarizing film disposed on the front side and the polarizing film disposed on the back side. Warping.

[Previous Technical Literature] [Patent Literature]

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

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

In the past, attention was paid only to warping in a high temperature environment, and as long as the problem was controlled, it was considered to solve the problem of warpage of the liquid crystal panel. However, it has been known that as the thickness of the liquid crystal cell becomes thinner, warpage of the liquid crystal cell is remarkably confirmed even if a slight dimensional change amount is generated in a hot and humid environment (60 ° C, 90%) to cause stress of the polarizing plate.

The inventions disclosed in Patent Documents 1 and 2 have a large warpage of the liquid crystal panel when used under wet heat conditions. Therefore, there is a problem that the liquid crystal panel is peeled off by the touch panel and the backlight unit is detached due to warpage.

Accordingly, an object of the present invention is to provide a polarizing plate set which can suppress not only warpage of a liquid crystal panel in a high temperature environment but also warpage of a liquid crystal panel in a humid heat environment.

The invention includes the following.

[1] A polarizing plate set includes a front side polarizing plate disposed on one surface side of the liquid crystal cell and a back side polarizing plate disposed on the other surface side; wherein the front side polarizing plate has a first protective film and The first polarizer is formed by laminating the first protective film and the first polarizer in a distance from the liquid crystal cell side; the first protective film has a slow axis, and is allowed to stand at 85 ° C and a humidity of 5%. When it is small, it has a shrinkage ratio of 0.1 to 1.0% in the direction of the slow axis, and the elastic modulus of the aforementioned slow axis direction at 85 ° C is 1000 MPa to 3000 MPa; the angle between the slow axis of the first protective film and the absorption axis of the first polarizer is 60° or more and 90° or less; and the back side polarizing plate has a second polarizer.

[2] The polarizing plate kit according to [1], wherein a ratio of a long side to a short side of the front side polarizing plate is from 1.2:1 to 2:1.

[3] The polarizing plate kit according to [1], wherein an angle between an absorption axis of the first polarizer and the short side of the front polarizer is 0 in the front side polarizing plate. °±1°.

[4] The polarizing plate kit according to any one of [1] to [3] wherein the thickness of the first polarizer is 15 μm or less.

[5] The polarizing plate kit according to any one of [1], wherein the first protective film has a thickness of 10 μm to 50 μm.

[6] The polarizing plate kit according to any one of [1] to [5] wherein the back side polarizing plate further has a reflective polarizing plate.

[7] A liquid crystal display device comprising: a liquid crystal cell; and a pair of polarizing plates disposed on both sides of the liquid crystal cell; and the polarizing plate according to any one of [1] to [6] In the liquid crystal display device, the first protective film, the first polarizer, the liquid crystal cell, and the second polarizer are laminated in this order.

According to the present invention, it is possible to obtain a polarizing plate set which has a small amount of warpage when disposed in a hot and humid environment and a high temperature environment, and which has no damage to the polarizer.

10‧‧‧ Front side polarizer

11‧‧‧1st protective film

11b‧‧‧ slow axis

12‧‧‧1st polarizer

12a‧‧‧ absorption axis of the first polarizer

13‧‧‧1st adhesive layer

20‧‧‧Back side polarizer

21‧‧‧2nd adhesive layer

22‧‧‧Back side protective film

23‧‧‧2nd polarizer

Absorption axis of 23a‧‧2nd polarizer

24‧‧‧3rd adhesive layer

25‧‧‧Reflective polarizer

30‧‧‧Liquid Crystal Unit

40‧‧‧Measurement point

50‧‧‧Polar plate

60‧‧‧ glass plate

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 relationship between the slow axis of the first protective film and the absorption axis of the first polarizer.

Fig. 3 is a view showing the relationship between the absorption axis of the first polarizer and the absorption axis of the second polarizer.

Fig. 4 is a schematic view showing the measurement points of the amount of warpage.

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

The polarizing plate kit of the present invention includes a front side polarizing plate disposed on one surface side of the liquid crystal cell and a back side polarizing plate disposed on the other surface side, wherein the front side polarizing plate has a first protective film and a first protective film a polarizer in which the first protective film and the first polarizer are sequentially stacked from the liquid crystal cell side; the first protective film has a slow axis, and is allowed to stand in an environment of 85 ° C and a humidity of 5% for 100 hours. When the slow axis direction has a shrinkage ratio of 0.1 to 1.0%, and the elastic modulus of the slow axis direction at 85 ° C is 1000 MPa to 3000 MPa; the slow axis of the first protective film and the first polarizer Absorption axis The angle formed is 60° or more and 90° or less; and the back side polarizing plate has a second polarizer.

In one aspect, the polarizing plate kit of the present invention may have the configuration illustrated in Fig. 1. For example, it includes a front side polarizing plate 10 disposed on one surface side of the liquid crystal cell 30 and a back side polarizing plate 20 disposed on the other surface side. In one aspect, the front side polarizing plate 10 has, for example, a first protective film 11, a first polarizer 12, and a first adhesive layer 13. Further, in one aspect, the back side polarizing plate 20 includes the second adhesive layer 21, the back side protective film 22, the second polarizer 23, the third adhesive layer 24, and the reflective polarizing plate 25. These layers may have other layers as needed.

In the front side of the present invention, the front side polarizing plate is bonded to, for example, the surface on the viewing side of the liquid crystal cell. On the other hand, the back side polarizing plate of the present invention is bonded to, for example, a surface on the opposite side to the surface on the viewing side of the liquid crystal cell. In one aspect, the back side polarizing plate can be bonded to the liquid crystal cell so as to be adjacent to a light source such as a backlight provided in the liquid crystal display device.

Although not shown in Fig. 1, for example, the polarizing plate set shown in Fig. 1 may be provided, and the layers other than the above layers may be provided on the front side polarizing plate 10 and the back side polarizing plate 20. In this case, the thickness of the newly disposed layer is included in the thickness of each polarizing plate. Further, the polarizers 12 and 23 and the protective films 11 and 22 are usually bonded via an adhesive layer. The thickness of the adhesive layer may be included in the thickness of each polarizing plate.

In the present invention, the first protective film has a slow axis. In one aspect, for example, when the polymer film used for the first protective film is extended in one direction, the film in-plane axis having the largest refractive index is generated in the extending direction. In the present invention Such an in-plane axis can be used as a slow axis. The direction of extension is not particularly limited, and it can be extended in the longitudinal direction of the polymer film used for the protective film.

Further, for example, when the polymer film is stretched in the longitudinal direction, the slow axis of the first protective film of the present invention and the absorption axis of the first polarizer can be arranged at a predetermined angle, in the technical field. A known method is to cut the stretched polymer film and use it as the first protective film.

In other aspects, for example, the polymer film used for the protective film can be extended in an oblique direction so as to have a slow axis inclined by a predetermined angle with respect to the longitudinal direction.

In another aspect, for example, when the polymer film used in the first protective film is biaxially stretched to exhibit birefringence in the biaxial direction, the film in-plane axis which is generated in the direction of the optical axis can be That is, the inner surface of the film produced in the direction in which the stretching ratio is large is taken as the slow axis.

In the present invention, the angle between the slow axis of the first protective film and the absorption axis of the first polarizer is 60° or more and 90° or less.

For example, as shown in Fig. 2, the first protective film 11 has a slow axis 11b. The angle α between the slow axis 11b and the absorption axis 12a of the first polarizer (not shown) is in the range of 60° or more and 90° or less, more preferably in the range of more than 60° and less than 90°, and more preferably It is in the range of 65° or more and 80° or less.

By having such an angular relationship, warpage under high temperature conditions and hot and humid conditions can be reduced.

The present invention includes a polarizing plate set having a front side polarizing plate and a back side polarizing plate having such an angular relationship, so that the amount of warpage under high temperature conditions and moist heat conditions is small, for example, when the back side polarizing plate and the backlight are bonded, Can suppress back The peeling of the light (shedding) can obtain a polarizing plate set having good optical characteristics.

In one aspect, the angle formed by the absorption axis of the first polarizer in the front side polarizer and the short side of the front side polarizer is 0° ± 1°, more preferably 0° ± 0.5°.

In one aspect, the angle formed by the absorption axis of the second polarizer in the back side polarizing plate and the short side of the back side polarizing plate is 90° ± 1°, more preferably 90° ± 0.5°.

In one aspect, the angle between the absorption axis of the first polarizer in the front side polarizer and the short side of the front side polarizer is 0°±1°, and the absorption of the second polarizer in the back side polarizer The angle formed by the short side of the shaft and the back side polarizing plate is 90° ± 1°.

By having such an axial relationship, for example, as shown in FIG. 3, the angle formed by the absorption axis 12a of the first polarizer 12 and the absorption axis 23a of the second polarizer in the back side polarizing plate 20 can be set to 90. ° ± 1 °, other aspects can be set to a range of 90 ° ± 0.5 °.

In still another aspect, the angle of the absorption axis of the first polarizer in the front side polarizer and the short side of the front side polarizer is 90° ± 1°, for example, 90° ± 0.5°. In this case, the angle formed by the absorption axis of the second polarizer in the back side polarizing plate and the short side of the back side polarizing plate is 0°±1°, and in other aspects, 0°±0.5°.

In one aspect, the angle formed by the absorption axis of the first polarizer and the absorption axis of the second polarizer is 90° ± 1°, more preferably 90° ± 0.5°. In the present invention, the state in which the absorption axis of the first polarizer and the absorption axis of the second polarizer are slightly orthogonal may be referred to as a state in which the polarizer is arranged in a crossed nicol state.

For example, when the absorption axis of the first polarizer and the absorption axis of the second polarizer are arranged in a state of a crossed polarizer, in one aspect, the absorption axis of the first polarizer in the front side polarizer is shorter than the front polarizer. The angle formed by the side is 0°±1°, and the angle formed by the absorption axis of the second polarizer in the back side polarizing plate and the short side of the back side polarizing plate is 90°±1°.

Further, in one aspect, when the absorption axis of the first polarizer and the absorption axis of the second polarizer are arranged in a crossed polarizer state, the angle between the slow axis of the first protective film and the absorption axis of the first polarizer It is in the range of 60° or more and less than 90°, more preferably in the range of 65° or more and 80° or less.

According to this aspect, the axial directions of the front side polarizing plate and the back side polarizing plate are hardly repeated, and it is considered that the contraction force which may be generated in each axial direction can be effectively dispersed. Thereby, for example, in a humid heat condition and a high temperature environment, warpage which may occur in the front side polarizing plate and the back side polarizing plate can be suppressed or reduced.

The polarizing plate kit of the present invention can maintain a balance between shrinkage which may occur in the front side polarizing plate and the back side polarizing plate, and warpage of the glass plate in the liquid crystal cell which may occur due to stress when the polarizing plates are contracted. As described above, since the balance between the contraction force of each polarizing plate and the warpage of the glass plate can be favorably maintained, the polarizing plate set of the present invention can greatly reduce the warpage due to the glass even when used under humid heat conditions and high temperature environments. The resulting display is uneven.

For example, when the absorption axis of the second polarizer in the back side polarizing plate is provided in the longitudinal direction, the stress at the time of contraction of the back side polarizing plate becomes dominant, and warpage may occur in the glass. On the other hand, if it is the polarizing plate cover of the present invention In the group, since the front side polarizing plate and the back side polarizing plate having a predetermined structure are used in combination, the degree of force acting on the glass can be made equal to the front side and the back side.

Although all of the above effects can be obtained when the absorption axis of the second polarizer in the back side polarizing plate is set in the short side direction, it is remarkable when the absorption axis of the second polarizer is set in the longitudinal direction.

In the present invention, the absorption axis of the first polarizer in the front side polarizing plate may be referred to as the absorption axis of the front side polarizing plate, and the second polarizer in the back side polarizing plate may be absorbed. The shaft serves as an absorption axis of the back side polarizing plate.

In one aspect, the ratio of the long side to the short side of the front side polarizer is from 1.2:1 to 2:1.

By the ratio of the long side to the short side of the front side polarizing plate having such a range, the warpage under high temperature conditions and moist heat conditions can be more effectively reduced.

In one aspect, the thickness of the first polarizer of the front side polarizing plate is 15 μm or less.

In one aspect, the thickness of the second polarizer of the back side polarizing plate is 15 μm or less. The thickness of the first polarizer and the thickness of the second polarizer may be the same or different.

The measurement of the thickness in each layer of the polarizing plate set of the present invention is carried out using a known measuring method in the art.

Here, exposure of the polarizing plate to a high temperature condition means that, for example, a polarizing plate or the like is exposed for at least 30 to 60 minutes at a temperature of 70 ° C to 95 ° C. It is preferred that the humidity in the high temperature condition is 10% or less.

Further, when the polarizing plate set of the present invention is exposed to high temperature conditions and the polarizing plate may slightly warp, for example, the first protective film, the first polarizer, and the first adhesive layer may be integrally formed and warped. In the same manner, for example, the second adhesive layer, the back side protective film, the second polarizer, the third adhesive layer, and the reflective polarizing plate may be integrally formed and warped.

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

The warpage can be evaluated by measuring the amount of warpage or the like in the present invention. For example, the amount of warpage can be evaluated by measuring the amount of warpage in the moist heat condition, or can be evaluated by measuring the amount of warpage in the high temperature condition.

For example, when the amount of warpage in the moist heat condition is measured, the first adhesive layer of the front side polarizing plate and the second adhesive layer of the back side polarizing plate are bonded to the surface and the back surface of the glass panel (this description is sometimes called In the case of a laminate, after standing in an environment of 60° C. and a humidity of 90% for 250 hours, the laminate was placed with the back side polarizing plate as the bottom, and the relative height of the horizontal surface of the measurement table was measured.

In the present invention, the moist heat condition is preferably in a temperature range of 40 ° C to 70 ° C and shows a state of humidity of 40% to 90%.

For example, the amount of warpage of the laminate in the moist heat condition is less than 1.00 mm, more preferably 0.8 mm or less.

With the polarizing plate set of the present invention, the warpage in the moist heat condition can be made to the above range. Further, since the warpage in the moist heat condition is in the above range, when the liquid crystal display device is incorporated, it is possible to obtain an effect that the end portion of the liquid crystal display device is less likely to cause light leakage.

Similarly, for example, when the amount of warpage of the laminate in the high temperature state is measured, the laminate is allowed to stand in an environment of 85° C. and a humidity of 5% for 250 hours, and then the in-plane is measured for the polarizing plate after standing. The relative height of the horizontal plane of the center portion is the in-plane center portion of the surface of the reflective polarizing plate opposite to the third adhesive layer.

For example, the amount of warpage of the laminate in a high temperature condition is less than 1.00 mm, more preferably 0.8 mm or less.

When the amount of warpage in such a range is displayed, for example, when assembled in a liquid crystal display device, light leakage is less likely to occur at the end of the liquid crystal display device.

[protective film]

The first protective film is laminated on the surface of the first polarizer opposite to the liquid crystal cell, and in one aspect is laminated on the surface of the first polarizer opposite to the first adhesive layer. Further, as described above, at least the first protective film has a slow axis.

In one aspect, the front side polarizing plate may have a second protective film on a surface of the first polarizer opposite to the first protective film.

Further, in one aspect, the back side protective film is laminated on the surface of the second polarizer opposite to the third adhesive layer. At least two types of the first protective film, the second protective film, and the back side protective film may be the same film, or may be different films.

The protective film may be a film made of 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 (for example). Lower olefinic resin, etc.) Polyolefin resin; cellulose resin such as cellulose triacetate or cellulose diacetate; polyester resin such as polyethylene terephthalate or polybutylene terephthalate; Acrylic 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; polyarylate A resin, a polyamidoximine resin, or a film made of a polyimide resin. Among them, a cellulose resin, a polyolefin resin, or an acrylic resin is preferably used, and a cellulose resin is particularly preferably used from the viewpoint of reducing the effect of warpage in a moist heat environment.

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

The cyclic polyolefin resin is a general term for a resin obtained by polymerizing 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 a copolymer of a cyclic olefin and a chain olefin such as ethylene or propylene ( Representative examples are random copolymers, and graft polymers which have been modified with unsaturated carboxylic acids or derivatives thereof, and such hydrides. Among them, a norbornene-based resin having a norbornene-based monomer such as a norbornene or a polycyclic norbornene-based monomer as a cyclic olefin is preferably used. In a preferred embodiment, the protective film of the present invention contains a cyclic polyolefin resin.

Cellulose resin means that it will be made of cotton linters or wood pulp (broadleaf a cellulose organic acid ester or a cellulose mixed organic acid in which a part or all of a hydrogen atom in a hydroxyl group of cellulose obtained from a raw material cellulose obtained from a raw material cellulose such as tree pulp or conifer pulp is substituted with an ethyl sulfonium group, a propyl fluorenyl group and/or a butyl sulfonyl group. ester. For example, cellulose acetate, propionate, butyrate, and a mixed ester of these may be contained.

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

The methyl methacrylate-based resin can be usually used in a radical polymerization initiator and optionally by using a monofunctional monomer mainly composed of methyl methacrylate and a polyfunctional monomer used as needed. The chain transfer agent is obtained by carrying out polymerization in the presence of a chain transfer agent.

The monofunctional monomer copolymerizable with methyl methacrylate may, for example, be ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, or Methyl acrylates other than methyl methacrylate such as 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, acrylic acid Acrylates such as phenyl ester, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate; methyl 2-(hydroxymethyl)acrylate, methyl 3-(hydroxyethyl)acrylate, 2 Hydroxy acrylic acid such as ethyl (hydroxymethyl)acrylate and butyl 2-(hydroxymethyl)acrylate Esters; 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; acrylonitrile and methacrylonitrile Unsaturated nitriles; unsaturated anhydrides such as maleic anhydride and citraconic anhydride; and unsaturated quinazones such as phenylmaleimide and cyclohexylmaleimide. These monomers may be used alone or in combination of two or more.

A polyfunctional monomer copolymerizable with methyl methacrylate, for example, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(methyl) Ethylene glycol or its oligomers, such as acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, and tetradecaethylene glycol (meth)acrylate The hydroxyl group at both ends is esterified with acrylic acid or methacrylate; the hydroxyl group at both terminals of propylene glycol or its oligomer is esterified with acrylic acid or methacrylate; neopentyl glycol di(meth)acrylate, hexanediol II (meth)acrylate, and butanediol di(meth)acrylate, etc., which are obtained by esterifying a hydroxyl group of a glycol with acrylic acid or methacrylic acid; an alkylene oxide adduct of bisphenol A and bisphenol A, Or the terminal hydroxyl groups of the halogen substituents are acrylated or methacrylated; the polyols such as trimethylolpropane and neopentyl alcohol are esterified with acrylic acid or methacrylate, and at the terminal hydroxyl groups Open-loop addition of epoxy propyl acrylate or epoxy propyl methacrylate; succinic acid, adipic acid, Diacids such as dicarboxylic acid, phthalic acid, halogen substitutes, and the like, and ring-opening addition of such alkylene oxide adducts to glycidyl acrylate or glycidyl methacrylate An epoxy group; an aryl (meth)acrylate; and a diaryl compound such as divinylbenzene. Among them, it is preferred to use ethylene glycol dimethacrylate, four Ethylene glycol dimethacrylate and neopentyl glycol dimethacrylate.

The methyl methacrylate-based resin may be a modified methyl methacrylate-based resin which is modified by a reaction between functional groups of the resin. The reaction may, for example, be an intramolecular decopolymerization 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 methyl 2-(hydroxymethyl) acrylate. A polymer chain internal dehydration condensation reaction of a hydroxyl group.

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

The protective film can be stretched and/or shrunk according to the mode of the liquid crystal display device to impart a suitable phase difference value. However, in the present invention, the angle formed by the slow axis of the first protective film and the absorption axis of the first polarizer is within a predetermined range, and the stretching and/or shrinking processing is performed.

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 viewpoint of strength or handleability. If it is the thickness in this range, the polarizer can be mechanically protected, and the contraction of the polarizer can be suppressed even when exposed to a hot and humid environment and a high temperature environment, and the optical characteristics of the stability can be maintained.

The shrinkage rate of the first protective film is preferably from 0.1 to 1.0%. Wai. When the shrinkage ratio exceeds 1.0%, the first protective film cannot suppress the shrinkage of the polarizer, and there is a problem that peeling of the polarizing plate occurs in a high-temperature/high-humidity environment.

The shrinkage ratio is a measured value of the dimensional change rate of the first protective film monomer when it is allowed to stand at 85 ° C and a humidity of 5% for 100 hours.

Further, in the present invention, the shrinkage ratio means the shrinkage ratio of the protective film in the slow axis direction. For example, the slow axis direction of the protective film may be slightly parallel to the long side direction or the short side direction of the protective film. Further, the slow axis of the protective film is a predetermined angle with respect to the flow direction (MD direction), and is, for example, preferably 60 to 90.

The elastic modulus of the first protective film at 85 ° C is in the range of 1,000 to 3,000 MPa. When it exceeds this range, the first protective film cannot suppress the shrinkage of the polarizer, and there is a problem that peeling of the polarizing plate occurs in a high-temperature/high-temperature and high-humidity environment. In the present specification, the elastic modulus of the first protective film means the elastic modulus of the first protective film in the slow axis direction.

The elastic modulus is a value calculated by performing a tensile test at a tensile speed of 1 mm/min in an environment of 85 ° C and a humidity of 5% after preheating the sample at 85 ° C and a humidity of 5% for 10 minutes.

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.

Examples of the water-based adhesive include an adhesive comprising a polyvinyl alcohol-based resin aqueous solution, and an aqueous two-liquid amine ester-based emulsion adhesive. Among them, a water-based adhesive including an aqueous solution of a polyvinyl alcohol-based resin is suitably used. Polyvinyl alcohol resin, in addition to polyvinyl acetate homopolymer of vinyl acetate In addition to the vinyl alcohol homopolymer obtained by the saponification treatment, a polyvinyl alcohol-based copolymer obtained by saponifying a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate, or A modified polyvinyl alcohol polymer such as a partially modified hydroxyl group. The aqueous binder may contain 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, after the polarizer is bonded to the protective film, it is preferred to carry out a drying step for removing water contained in the aqueous adhesive. After the drying step, a ripening step of, for example, aging 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, a photoreactive resin, and a binder. Resin and photoreactive crosslinker, etc. Examples of the polymerizable compound include a photocurable epoxy monomer, a photocurable acrylic monomer, and a photocurable amine ester monomer; and a photopolymerizable monomer. Oligomer. 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 are preferably used.

When the active energy ray-curable adhesive is used, after the polarizer and the protective film are bonded, if necessary, a drying step is performed, and then the active energy ray is irradiated to harden the active energy ray-curable adhesive. Steps. The light source of the active energy ray is not particularly limited, and 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 for an insect trap, and a black light can be used. Lights, microwaves, mercury lamps, metal halide lamps, etc.

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

[Polarizer]

The polarizer is an absorptive polarizer having a property of absorbing linear polarized light having a vibrating surface parallel to its absorption axis and penetrating linearly polarized light having a vibrating surface orthogonal to the absorption axis (parallel to the transmission axis). . The first polarizer and the second polarizer used in the polarizing plate kit of the present invention may be the same polarizer or different polarizers. For example, it is suitable to use a dichroic dye to adsorb a polarizing film oriented on a polyvinyl alcohol-based 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 adsorbing the dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye; a step of treating a polyvinyl alcohol-based resin film having a dichroic dye adsorbed thereto with an aqueous solution of boric acid; and a step of washing with water after treatment with an aqueous solution of boric acid.

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 polyvinyl acetate of a vinyl acetate homopolymer. Examples of other monomers copolymerizable with vinyl acetate, including unsaturated carboxylic acids, olefins, ethylene Alkyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is usually from about 85 to 100 mol%, preferably from 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, an aldehyde-modified polyvinyl formal or polyvinyl acetal may 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 raw material film of a polarizer (polarizing film). The film forming method of the polyvinyl alcohol-based resin is not particularly limited, and a known method is employed. The thickness of the polyvinyl alcohol-based raw material film is not particularly limited. However, in order to make the thickness of the polarizer 15 μm or less, it is preferable to use about 5 to 35 μm. More preferably, a raw material film of 20 μm or less is 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 uniaxially extending after dyeing, the uniaxial stretching can be carried out before boric acid treatment or boric acid treatment. Again, uniaxial stretching can be performed in these plurality of stages.

In the case of uniaxial stretching, it is possible to extend on a single axis between rolls having different circumferential speeds, or to use a heat roll and extend on a single axis. Further, the uniaxial stretching may be a dry stretching in which stretching is carried out in the air, or a wet stretching in which a polyvinyl alcohol-based resin film is stretched in a swollen state using a solvent. The stretching ratio is usually about 3 to 8 times.

A method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye may be, for example, immersing the film in an aqueous solution containing a dichroic dye. method. As the dichroic dye, iodine or a dichroic organic dye can be used. Moreover, it is preferable that the polyvinyl alcohol-based resin film is immersed in water before the dyeing treatment.

By the iodine dyeing treatment, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The iodine content 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. Further, the temperature of the aqueous solution may be about 20 to 40 °C. On the other hand, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic organic dye is usually employed by dyeing a dichroic organic dye. 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 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.

The boric acid treatment after dyeing the 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, the aqueous solution containing boric acid preferably 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 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 temperature of the water in the water washing process is usually 5 Up to 40 ° C.

After washing with water, drying treatment was carried out 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. The thickness of the polarizer is 15 μm or less, which is advantageous for thinning of a polarizing plate or even a 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 within the range not departing from the scope of the invention.

[1st and 2nd adhesive layers]

The pressure-sensitive adhesive forming the first adhesive layer and the second adhesive layer may be appropriately selected as long as it is suitable for exposure to a high temperature environment, a hot and humid environment, or a high temperature and low temperature. It is sufficient that the degree of adhesion such as peeling does not occur in the environment.

For example, the first and second adhesive layers can be used for bonding various polarizing plates to liquid crystal cells.

The adhesive to be used for the first and second adhesive layers may, for example, be an acrylic adhesive, a polyoxygen adhesive, or a rubber adhesive, and has transparency, weather resistance, heat resistance, and processability. In view of it, it is especially preferred as an acrylic adhesive.

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

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

In the adhesive, a tackifier, a plasticizer, a filler composed of glass fiber, glass beads, metal powder, other inorganic powder, etc., a pigment, a colorant, a filler, an antioxidant, and the like may be appropriately blended as needed. Various additives such as ultraviolet absorbers, antistatic agents, and decane coupling agents.

The adhesive layer is usually formed by applying an adhesive solution to the release sheet and drying it. 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, a spray method, or the like. The release sheet provided with the adhesive layer can be utilized by a method of transferring it or the like. The thickness of the first adhesive layer and the second 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 embodiment, the first adhesive layer and the second adhesive layer can suppress the destruction of the polarizing plate by having such a thickness, and when the liquid crystal display device is assembled, light leakage at the end portion of the liquid crystal display device can be suppressed. . Further, the thickness of the first adhesive layer and the second adhesive layer can be appropriately adjusted so that the thickness of the interlayer is within a predetermined range, and the thicknesses of the first adhesive layer and the second adhesive layer may be the same or different. The thickness.

The storage elastic modulus at 80 ° C of the first adhesive layer and the second adhesive layer is preferably 0.015 MPa or more, and more preferably 0.03 MPa or more. If the storage elastic modulus of the adhesive layer is less than 0.015 MPa, aggregation failure of the first adhesive layer and the second adhesive layer may occur, and if the aggregation damage is remarkable, not only the appearance of the polarizing plate may be adversely affected, but also When assembled in a liquid crystal display device, light leakage occurs at the end of the liquid crystal display device, which adversely affects the display. Preferably, the first adhesive layer and the second adhesive layer are at 80. The storage elastic modulus at °C is 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 first adhesive layer, the second adhesive layer, and the glass or the panel is deteriorated, and bubbles are likely to be generated between the layers.

Before the first adhesive layer and the second adhesive layer are bonded to other members, a separator may be provided to protect the surface. For example, a film made of a transparent resin such as polyethylene terephthalate is used as a treatment agent for a release agent such as a polyoxymethylene system.

[Reflective polarizer]

A reflective polarizing plate, also referred to as a brightness enhancing film, uses a polarizing conversion element that separates light emitted from a light source (backlight) into translucent and reflected polarized or scattered polarized light. As described above, the reflection type polarizing plate and the polarizing plate are arranged in a predetermined relationship, whereby the returning light of the linearly polarized light emitted from the polarizing plate can be improved by the reflected light of the reflected polarized light or the scattered polarized light. For example, the reflective polarizing plate is laminated to the third 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 multiple film that penetrates a linearly polarized light in a vibration direction and reflects linear polarization in another vibration direction, and a specific example thereof is a 3M system DBEF (Japanese Patent Laid-Open No. 4-268505) Wait). 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 polarizer has at least two layers of films, and at least two of the stretched films are refractive index anisotropy.

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 to emit a reflected polarized light even in a visible light region (US Patent No. 6288840, etc.) A film in which metal fine particles are added to a polymer matrix and stretched (Japanese Unexamined Patent Publication No. Hei No. Hei No. 8-184701).

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 on the surface of the reflective polarizing plate opposite to the first adhesive layer. By forming the optical layer, the adhesion to the backlight strip 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 thinning of the polarizing plate.

In the polarizing plate kit of the present invention, the surface of the third polarizing layer side of the reflective polarizing plate can be surface-activated. This surface activation treatment is performed before the reflective polarizing plate and the third adhesive layer are bonded together. Thereby, peeling between the third adhesive layer and the reflective polarizing plate is less likely to occur in a moist heat and a high-temperature environment, and a polarizing plate excellent in wet heat durability and high-temperature durability 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, discharge treatment such as corona treatment, plasma treatment, glow discharge treatment, flame treatment, ozone treatment, UV ozone treatment, ultraviolet treatment, electron beam treatment, or the like. Ionization active line treatment and the like. For the wet treatment, for example, ultrasonic treatment using a solvent such as water or acetone, an alkali treatment, a primer treatment, or the like can be exemplified. 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 moist heat environment and the productivity of the polarizing plate. By the surface activation treatment, even when the thickness of the reflective polarizing plate is thin, for example, 30 μm or less, peeling between the third adhesive layer and the reflective polarizing plate in a moist heat environment can be effectively suppressed. Further, the surface of the third adhesive layer on the side of the brightness-reflective polarizing plate may be subjected to a surface activation treatment together.

[3rd adhesive layer]

The third adhesive layer is a layer interposed between the second polarizer and the reflective polarizer. The third adhesive layer is typically laminated directly on the polarizer such that the second polarizer is in contact with the third adhesive layer. The third adhesive layer may be formed of the same material as the first adhesive layer or the second adhesive layer. Specifically, the third adhesive layer may be composed of an adhesive composition containing a resin such as an acrylic, rubber, amine ester, ester, polyoxyn, or polyvinyl ether as a main component. Among them, an acrylic resin excellent in transparency, weather resistance, heat resistance, and the like is preferably used as the adhesive composition of the matrix polymer. The adhesive composition may be an active energy ray hardening type or a thermosetting type. The third adhesive layer and the first adhesive layer or the second adhesive layer may be formed of the same material, or may be formed of different materials.

The third adhesive layer is preferably at a temperature of 23 to 80 ° C. The storage elastic modulus of 0.15 to 1.2 MPa is shown in the circumference. Thereby, it is possible to suppress the dimensional change which easily occurs with the shrinkage of the polarizer in a high temperature and a hot and humid environment, and to improve the durability of the polarizing plate. Moreover, even 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 high-temperature and hot-heat environment, fluctuations in the polarizing plate can be suppressed, so that the liquid crystal display device can be improved. Trustworthiness.

"The storage elastic modulus of 0.15 to 1.2 MPa in the temperature range of 23 to 80 ° C" means that the storage elastic modulus in any of the ranges is a value within the above range. Therefore, even if the storage elastic modulus at 23 ° C and 80 ° C is individually described, each storage elastic modulus is included in the above range.

The storage elastic modulus generally decreases as the temperature rises. Therefore, if the storage elastic modulus at 23 ° C and 80 ° C is in the above range, it can be considered that the storage elastic modulus in the above range is displayed in the range temperature. The storage elastic modulus of the adhesive layer can be measured using a commercially available viscoelasticity measuring device, for example, a viscoelasticity measuring device "DYNAMIC ANALYZER RDA II" manufactured by REOMETRIC Co., Ltd., which will be described later.

The method for adjusting the storage elastic modulus to the above range includes further adding an oligomer to the adhesive composition containing the matrix polymer and the crosslinking agent, specifically, an amine ester acrylate-based oligo The polymer forms an active energy ray-curable adhesive composition (preferably an ultraviolet curable adhesive composition). More preferably, the adhesive layer is suitably cured by irradiating the active energy ray.

The thickness of the third adhesive layer may be 30 μm or less. Better It is 25 μm or less, particularly preferably 20 μm or less, and particularly preferably 15 μm or less. By making the thickness of the third adhesive layer 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 third adhesive layer can be appropriately adjusted so that the thickness of the interlayer is within a predetermined range.

[Manufacturing method of front side polarizing plate]

The front side polarizing plate of the present invention includes, for example, a first protective film bonded to one surface of the first polarizer via an adhesive layer. At this time, the angle formed by the slow axis of the first protective film and the absorption axis of the first polarizer is brought into a predetermined angle.

Further, for example, the first adhesive layer is bonded to the surface of the first polarizer opposite to the first protective film.

In one aspect, the second protective film is bonded to the surface of the first polarizer opposite to the first protective film via the adhesive layer, and the second protective film is opposite to the first polarizer. The first adhesive layer is attached to the surface. Further, the separator can be temporarily adhered to the outside of the first adhesive layer.

As described above, the front side polarizing plate of the present invention is known in the art as long as it is bonded such that the angle between the slow axis of the first protective film and the absorption axis of the first polarizer becomes a predetermined angle. Made by method.

[Method of Manufacturing Back Side Polarizing Plate]

In one aspect, a step of laminating a reflective polarizing plate on a second polarizer, wherein the reflective polarizer is laminated with a third adhesive layer, is produced.

In addition, the back side polarizing plate of the present invention includes, for example, a back side protective film bonded to one surface of the second polarizer via an adhesive layer, and an area layer opposite to the second polarizer on the back side protective film. The second adhesive layer and the second polarizer are bonded to the surface on the opposite side of the back side protective film, and the third adhesive layer is formed on the opposite side of the third adhesive layer from the second polarizer. board. The back side polarizing plate in one embodiment is obtained by the above steps. Further, the separator may be temporarily adhered to the outer surface of the second adhesive layer, or the surface of the third adhesive layer and the reflective polarizing plate may be surface-activated.

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

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

[Liquid Crystal Display Device]

The polarizing plate kit of the present invention is preferably applicable to a liquid crystal display device. The liquid crystal display device includes a liquid crystal cell and a polarizing plate kit of the present invention bonded to the surface of the liquid crystal cell.

The front side polarizing plate can be bonded to the liquid crystal cell via the first adhesive layer, for example. The front side polarizing plate of the present invention can be used as a polarizing plate disposed on the viewing side of the liquid crystal cell. For example, the liquid crystal display device includes a front side polarizing plate such that the first protective film is the outermost layer.

Further, the back side polarizing plate of the present invention can be used as a polarizing plate disposed on the backlight side of the liquid crystal cell. The back side polarizing plate is bonded to the liquid crystal cell, and can be carried out, for example, via the second adhesive layer.

The driving method of the liquid crystal cell may be any conventionally known, but 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 each polarizing plate to an organic electroluminescence display via a first adhesive layer and a second adhesive layer.

(Example)

The present invention will be further specifically described by the following examples, but the present invention is not limited to the examples. In the examples, "%" and "parts" indicating the content or the amount used are based on weight unless otherwise specified.

Further, the thickness of the film was measured according to the following.

(1) Determination of film thickness

It was measured using a digital micrometer "MH-15M" manufactured by Nikon Corporation.

[Manufacture of polarizer]

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 in a dry manner, and further immersed in pure water at 60 ° C for 1 minute while being kept tight. The aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.05/5/100 was immersed at 28 ° C for 60 seconds. Thereafter, the aqueous solution of potassium iodide/boric acid/water is 8.5/8.5/100 by weight. Immersion at 72 ° C for 300 seconds. Then, it 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 thickness of the polyvinyl alcohol film.

When the first polarizer is used as the first polarizer, the first polarizer is produced such that the angle formed by the absorption axis of the first polarizer and the short side of the front polarizer is 0°±0.5°.

On the other hand, when the second polarizer in the back side polarizing plate is used, the second angle is formed by the angle between the absorption axis of the second polarizer and the short side of the back side polarizing plate being 90°±0.5°. Polarizer.

The following are used for the protective film.

[Protective film-1]

A cellulose triacetate film manufactured by KONICA MINOLTA Co., Ltd., obliquely extending; KC4UGR-HC (thickness 44 μm, in-plane retardation at wavelength 590 nm = 106 nm, phase difference in thickness direction at wavelength 590 nm = 75 nm, Rth (590) / Re (590) = 0.71, Re (450) / Re (550) = 0.96, Re (630) / Re (550) = 1.02 optical film), with a tilt of 45 ° with respect to MD (flow direction) On the slow axis, the shrinkage rate is 0.2% in the slow axis direction and 2500 MPa in the slow axis direction at 85 °C.

[Protective film-2]

A cycloolefin resin film (manufactured by Nippon Zeon Co., Ltd.) having a thickness of 13 μm was used. In the in-plane retardation of wavelength 590 nm (Re(590)) = 0.8 nm, retardation in the thickness direction at a wavelength of 590 nm (Rth(590)) = 3.4 nm, retardation in the thickness direction at a wavelength of 483 nm (Rth (483)) = 3.5 nm At a wavelength of 755 nm Thickness direction retardation (Rth (755)) = 2.8 nm.

[Protective film-3]

A cellulose triacetate film (thickness: 20 μm, in-plane retardation at a wavelength of 590 nm = 1.2 nm, thickness direction retardation at a wavelength of 590 nm = 1.3 nm) manufactured by KONICA MINOLTA Co., Ltd.

[Protective film-4]

The stretched acrylic resin film; an optical film having a thickness of 40 μm and a phase difference of 3 nm in a wavelength of 590 nm and a phase difference of -3 nm in a thickness direction of 590 nm. It has a slow axis which is almost parallel with respect to MD (flow direction), the shrinkage rate is 0.1% in the slow axis direction, and the elastic modulus in the slow axis direction of 85 ° C is 1800 MPa.

[Reflective polarizer]

A brightness enhancement film (manufactured by 3M, trade name Advanced Polarized Film, Version 3) having a thickness of 26 μm was used.

[Preparation of water-based adhesive]

3 parts of carboxy-modified polyvinyl alcohol (KL-318, manufactured by Kuraray Co., Ltd.) was dissolved in 100 parts of water, and a polyamine-based epoxy-based additive containing a water-soluble epoxy compound was added to the aqueous solution (Sumika Chemtex Co., Ltd. limited) Sumirez Resin (registered trademark) 650 (30) manufactured by the company, 1.5 parts of an aqueous solution having a solid concentration of 30%, is used as a water-based adhesive.

[Adhesive layer-1]

A commercially available adhesive sheet having an acrylic pressure-sensitive adhesive layer having a thickness of 20 μm in a release-treated area layer of a polyethylene terephthalate film (release film) having a thickness of 38 μm which had been subjected to mold release treatment was used. The storage elastic modulus of the adhesive layer was 0.05 MPa at 23 ° C and 0.04 MPa at 80 ° C.

[Adhesive layer-2]

An amine ester acrylate oligomer and an isocyanate crosslinking agent were added to a copolymer of butyl acrylate and acrylic acid to obtain an organic solvent solution, and the organic solvent solution was applied by a die coater so as to have a thickness of 5 μm after drying. The release-treated surface of a polyethylene terephthalate film (release film) having a thickness of 38 μm which had been subjected to mold release treatment was dried and dried to obtain an adhesive sheet in which an adhesive layer was laminated. The storage elastic modulus of the adhesive layer was 0.40 MPa at 23 ° C and 0.18 MPa at 80 ° C.

(Example 1)

[Production of front side polarizer-1]

On one surface of the first polarizer, a protective film-1 as a first protective film is laminated via a water-based adhesive. In the same manner as the surface on which the first protective film is laminated on the first polarizer, the protective film 2 as the second protective film is laminated via a water-based adhesive.

After laminating, the film was dried at 80 ° C for 5 minutes to bond the first protective film, the first polarizer and the second protective film.

The first adhesive layer laminated on the release film is bonded to the surface of the second protective film opposite to the first polarizer bonding surface.

In the first embodiment, the angle between the slow axis of the first protective film and the absorption axis of the first polarizer is 60°.

[Production of Back Side Polarizer-1]

On one surface of the second polarizer, a protective film-3 as a back side protective film is laminated via a water-based adhesive. After laminating, the film was dried at 80 ° C for 5 minutes to bond the back side protective film and the second polarizer. The adhesive layer-2 as a third adhesive layer laminated on the release film is bonded to the surface on the opposite side of the bonding surface of the second polarizer and the back side protective film.

The adhesive layer-1 as a second adhesive layer laminated on the release film is bonded to the surface on the opposite side of the bonding surface of the back side protective film and the second polarizer.

Moreover, the absorption axis direction of the second polarizer is bonded to the longitudinal direction of the protective film in parallel.

In this manner, the polarizing plate precursor A-1 in which the second adhesive layer, the back side protective film, the second polarizer, and the third adhesive layer are laminated in this order is formed.

The release film on the third adhesive layer in the polarizing plate precursor was peeled off. The third adhesive layer and the brightness enhancement film in the polarizing plate precursor A-1 are bonded to each other to obtain a second adhesive layer, a back side protective film, a second polarizer, a third adhesive layer, and a reflection layer. A polarizing plate on the back side of a polarizing plate (brightness enhancing film).

The relationship of various axial angles in the polarizing plate thus obtained is shown in Table 1.

With respect to Examples 2 to 6 and Comparative Examples 1 to 5, a polarizing plate was produced in the same manner as described above. Moreover, the relationship of the axial angle in the polarizing plate is as shown in Table 1 and Table 2.

(Example 7)

The "front side polarizing plate-2" was used as the front side polarizing plate, and the "back side polarizing plate-1" was used as the back side polarizing plate.

[Production of front side polarizer-2]:

On one surface of the first polarizer, a protective film-2 as a second protective film is laminated via a water-based adhesive. After laminating, the film was dried at 80 ° C for 5 minutes to bond the second protective film and the first polarizer. On the surface of the first polarizer opposite to the second protective film layer, a protective film-4 as a first protective film is laminated via a UV curable adhesive. After lamination, the first protective film and the first polarizer are bonded to each other by irradiating ultraviolet rays.

The first adhesive layer laminated on the release film is bonded to the surface of the second protective film opposite to the first polarizer bonding surface.

In the seventh embodiment, the angle between the slow axis of the first protective film and the absorption axis of the first polarizer is 60°.

With respect to Examples 8 to 12 and Comparative Examples 6 to 10, a polarizing plate was produced in the same manner as in Example 7. Moreover, the relationship of the axial angle in the polarizing plate is as shown in Tables 3 and 4.

Physical property evaluation of polarizing plates

The evaluation of the obtained various polarizing plates was carried out according to the following measurement method.

(High temperature / high humidity heat test)

Production of test strips

The front side polarizing plate was cut into a long side of 155 mm × a short side of 96 mm (an absorption axis having a polarizing plate in the short side direction).

The release film on the first adhesive layer in the front side polarizing plate was cut off, and bonded to a glass plate having a thickness of 0.4 mm and a length of 160 mm × a short side of 102 mm via the first adhesive layer. The surface of the glass plate opposite to the front side polarizing plate bonding surface is bonded to the long side by 155 mm × short side 96 mm (on the long side) via an acrylic adhesive layer (second adhesive layer). The back side polarizing plate having the absorption axis of the polarizing plate in the direction.

(warp in high temperature environment)

In the laminated body having the front side polarizing plate/glass plate/back side polarizing plate, the laminated body 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 was on the upper side. The sample was taken out from a high-temperature environment, and the laminate was placed on the measurement stand of a two-dimensional measuring instrument (NEXIV (registered trademark) MR-12072, manufactured by Nikon Co., Ltd.) with the front side polarizing plate as the upper side.

Then, the surface of the measuring table was focused, and the focus was obtained at 25 points on the laminated body surface having the front side polarizing plate/glass plate/back side polarizing plate as a reference, and the height from the reference focus was measured. The difference between the maximum value and the minimum value of the height in the measurement point at 25 points was taken as the amount of warpage. Figure 4 A schematic diagram showing the measurement points of the amount of warpage. 40 is a "measurement point", 50 is a polarizing plate, and 60 is a glass plate.

The 25 "measurement points" are arranged in a 7 mm inner region from the end of the polarizing plate, and are arranged at intervals of about 20 mm in the short side direction and about 35 mm in the longitudinal direction.

The determination was made in the following manner. The results are shown in Table 1 (Example) and Table 2 (Comparative Example). Further, the results of Example 7 and the like are shown in Table 3 (Examples), and the results of Comparative Example 6 and the like are shown in Table 4 (Comparative Example). Further, in the examples, the floating or peeling of the film was not confirmed in any of the samples.

<decision>

When the amount of warpage of the glass sample which is left to stand in a high temperature environment is 0.8 mm or less, it is "○".

When the amount of warpage of the glass sample which is left to stand in a high temperature environment exceeds 0.8 mm, it is "x".

(warping of hot and humid environment)

In the laminate having the structure of the back side polarizing plate/glass/front side polarizing plate, the front side polarizing plate was placed on the upper side, and allowed to stand in an environment of 60° C. and a humidity of 90% for 250 hours. The laminate was placed on a measurement stand of a two-dimensional measuring instrument (NEXIV (registered trademark) MR-12072, manufactured by Nikon Co., Ltd.) with the front side polarizing plate as the upper side. The measurement was carried out in the same manner as the test in a high temperature environment.

The determination was made in the following manner. The results are shown in Table 1 (Example) and Table 2 (Comparative Example). Moreover, in the examples, none of the samples were confirmed. Float or peel off to the film.

<decision>

When the amount of warpage of the glass sample which was left to stand in a hot and humid environment was 0.8 mm or less, it was "◎".

When the amount of warpage of the glass sample which was left to stand in a hot and humid environment was less than 1.0 mm, it was "○".

When the amount of warpage of the glass sample which is left to stand in a hot and humid environment is 1.0 mm or more, it is "x".

In view of such a result, the polarizing plate set of the present invention can obtain a thin polarizing plate set. Further, even when the polarizing plate is exposed to a high temperature condition or a hot and humid environment, the warpage of the laminated body including the polarizing plate can be suppressed.

As described above, the polarizing plate set of the present invention has a small amount of warpage when disposed in a hot and humid environment and a high-temperature environment, and therefore it is considered that there is no peeling from the touch panel and the backlight unit is detached. Moreover, it is related to the reduction of display due to warpage even when exposed to a high temperature/humid heat environment.

[Industrial availability]

According to the present invention, for example, a polarizing plate set that suppresses warpage of a polarizing plate and a reflective polarizing plate can be provided.

10‧‧‧ Front side polarizer

11‧‧‧1st protective film

12‧‧‧1st polarizer

13‧‧‧1st adhesive layer

20‧‧‧Back side polarizer

21‧‧‧2nd adhesive layer

22‧‧‧Back side protective film

23‧‧‧2nd polarizer

24‧‧‧3rd adhesive layer

25‧‧‧Reflective polarizer

30‧‧‧Liquid Crystal Unit

Claims (7)

A polarizing plate set includes a front side polarizing plate disposed on one surface side of the liquid crystal cell and a back side polarizing plate disposed on the other surface side; wherein the front side polarizing plate has a first protective film and a first polarizing film The first protective film and the first polarizer are sequentially laminated from the liquid crystal cell side, and the first protective film has a slow axis, and is allowed to stand in an environment of 85° C. and a humidity of 5% for 100 hours. a shrinkage ratio of 0.1 to 1.0% in the slow axis direction, and an elastic modulus of 1000 MPa to 3000 MPa in the slow axis direction at 85 ° C; the slow axis of the first protective film and the absorption axis of the first polarizer The angle formed is 60° or more and 90° or less; and the back side polarizing plate has a second polarizer. The polarizing plate kit of claim 1, wherein the ratio of the long side to the short side of the front side polarizing plate is from 1.2:1 to 2:1. The polarizing plate set according to claim 1 or 2, wherein an angle formed by an absorption axis of the first polarizer and the short side of the front polarizer is 0°± 1°. The polarizing plate kit according to any one of claims 1 to 3, wherein the first polarizer has a thickness of 15 μm or less. The polarizing plate kit according to any one of claims 1 to 4, wherein the first protective film has a thickness of 10 μm to 50 μm. The polarizing plate cover according to any one of claims 1 to 5 The group, wherein the back side polarizing plate further has a reflective polarizing plate. A liquid crystal display device comprising: a liquid crystal cell; and a pair of polarizing plates disposed on both sides of the liquid crystal cell; wherein the pair of polarizing plates are the polarizing plate set according to any one of claims 1 to 6; In the liquid crystal display device, a first protective film, a first polarizer, a liquid crystal cell, and a second polarizer are laminated in this order.