KR100832760B1 - Elliptically polarizing plate and image display apparatus using the same - Google Patents

Abstract

It is to provide an elliptical polarizing plate having a very thin, wide viewing angle, an easy manufacturing method thereof, and an image display device using an elliptic polarizing plate.

Elliptical polarizing plate of the present invention, a polarizer; A protective layer formed on one side of the polarizer; a first birefringent layer functioning as a λ / 2 plate; And a second birefringent layer functioning as a λ / 4 plate in this order, and an angle formed by the absorption axis of the polarizer and the slow axis of the first birefringent layer is α, and the absorption axis of the polarizer and the slow axis of the second birefringence layer are When the angle to be formed is β, the angle α is 10 ° to 20 ° or -10 ° to -20 °, and the angle β is 65 ° to 85 ° or 5 ° to 25 °.

Elliptical polarizer, image display device

Description

ELLIPTICALLY POLARIZING PLATE AND IMAGE DISPLAY APPARATUS USING THE SAME}

The present invention relates to an elliptical polarizing plate and an image display device using the same. More specifically, the present invention relates to an elliptical polarizing plate having a wide band and wide viewing angle while being very thin, and an image display device using the same.

Generally, various optical films which combined polarizing film and retardation plate are used for various image display apparatuses, such as a liquid crystal display device and an electroluminescent (EL) display, in order to perform optical compensation.

The circularly polarizing plate which is a kind of said optical film can be manufactured by combining a polarizing film and a (lambda) / 4 plate normally. However, the λ / 4 plate exhibits a characteristic in which the phase difference value increases as the wavelength becomes a shorter wavelength side, a so-called "positive wavelength dispersion characteristic", and in general, the wavelength dispersion characteristic is large. Therefore, there is a problem in that desired optical properties (for example, functions as a λ / 4 plate) cannot be exhibited over a wide wavelength range. In order to avoid such a problem, for example, norbornene-based films and modified polycarbonate-based films have been proposed as retardation plates showing wavelength dispersion characteristics, so-called "back-dispersion characteristics," in which the phase difference value increases as the wavelength becomes a longer wavelength side. . However, such a film has a cost problem.

For this reason, the wavelength dispersion characteristics of the λ / 4 plate can now be achieved by combining a λ / 4 plate having a positive wavelength dispersion characteristic with a phase difference plate or a λ / 2 plate whose phase difference value increases with the long wavelength side, for example. The method of correction is employ | adopted (for example, refer patent document 1).

Thus, when combining a polarizing film, (lambda) / 4 plate, and (lambda) / 2 plate, it is necessary to adjust the angle of each optical axis, ie, the absorption axis of a polarizing film, and the slow axis of each retardation plate. However, both the polarizing film and the retardation plate made of the stretched film also have their optical axes generally dependent on the stretching direction, and in order to laminate them so that the absorption axis and the slow axis are at the desired angles, the respective films are cut and laminated along the direction of the optical axis. Should be. Specifically, the absorption axis of the polarizing film is usually parallel to the stretching direction, and the slow axis of the retardation plate is also parallel to the stretching direction. For this reason, in order to laminate | stack a polarizing film and a retardation plate so that the angle of an absorption axis and a slow axis may be 45 degrees, it is necessary to cut out either film in the direction of 45 degrees with respect to a longitudinal direction (stretching direction). . Thus, when a film is cut out and then attached, for example, there is a possibility that a deviation occurs in the angle of the optical axis in each cut film, and as a result, there is a problem that a quality deviation occurs between products. In addition, there is a problem in that it takes a lot of cost and time. In addition, there is a problem in that waste increases according to cutting, and production of a large film is difficult.

About this problem, although the method of adjusting a extending | stretching direction by extending | stretching a polarizing film or a retardation plate in oblique direction is also reported (for example, refer patent document 2), but there exists a problem that adjustment is difficult.

In addition, the demand for thinning an image display device has been increasing in recent years. In connection with this, there is an increasing demand for thinning of optical films including circular polarizing plates.

Patent Document 1: Japanese Patent No. 3174367

Patent Document 2: Japanese Unexamined Patent Publication No. 2003-195037

Disclosure of the Invention

Problems to be Solved by the Invention

This invention is made | formed in order to solve the said conventional subject, and the objective is to provide the elliptical polarizing plate of broadband and wide viewing angle, and the image display apparatus using the same while being very thin.

Means to solve the problem

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining the characteristic of an elliptically polarizing plate, this inventor transfers the birefringence layer formed by apply | coating the liquid crystal composition containing a liquid crystal material and a chiral agent to a specific base material, and is (lambda) / 4 which is very thin and has the outstanding optical characteristic. By forming the plate, it was found that the above object can be achieved, and the present invention has been completed.

The elliptical polarizing plate of the present invention includes a polarizer; A protective layer formed on one side of the polarizer; a first birefringent layer functioning as a λ / 2 plate; the second birefringent layer serving as a λ / 4 plate in this order, and the angle formed by the absorption axis of the polarizer and the slow axis of the first birefringent layer is α, the absorption axis of the polarizer and the second birefringence layer When the angle formed by the slow axis is β, the angle α is 10 ° to 20 ° or -10 ° to -20 °, and the angle β is 65 ° to 85 ° or 5 ° to 25 °. In a preferred embodiment, the thickness of the first birefringent layer is 0.5 to 5 µm. In addition, the thickness of the second birefringent layer is 0.3 to 3 µm.

In a preferred embodiment, the first birefringent layer is formed using a liquid crystal material, and the second birefringent layer is formed using a liquid crystal composition containing a liquid crystal material and a chiral agent. In a preferred embodiment, the liquid crystal material forming the second birefringent layer is at least one of the compounds represented by the following formulas (4) to (19), and the chiral agent is represented by the following formulas (24) to (44): At least one of the compounds. In a particularly preferred embodiment, the liquid crystal material is a compound represented by the following formula (10), and the chiral agent is a compound represented by the following formula (32):

[Formula 1]

[Formula 2]

[Formula 3]

According to another aspect of the present invention, a method of manufacturing an elliptical polarizing plate is provided. This manufacturing method includes a step of performing an orientation treatment on the surface of the transparent protective film (T); Forming a first birefringent layer on the surface subjected to the alignment treatment of the transparent protective film (T); Laminating the polarizer on the surface of the transparent protective film T, wherein the polarizer and the first birefringent layer are disposed on opposite sides with the transparent protective film T interposed therebetween, and the polarization of the first birefringent layer And laminating a second birefringent layer on the surface. In a preferred embodiment, the transparent protective film (T), the first birefringent layer, the polarizer, and the second birefringent layer are long films, and the long sides thereof are attached and laminated.

In a preferred embodiment, the step of forming the first birefringent layer includes a step of applying a coating liquid containing a liquid crystal material and orientating the coated liquid crystal material at a temperature at which the liquid crystal material exhibits a liquid crystal phase. Process. In a further preferred embodiment, the liquid crystal material contains a polymerizable monomer and / or a crosslinkable monomer, and the alignment step of the liquid crystal material further includes performing a polymerization treatment and / or a crosslinking treatment. In a preferred embodiment, the polymerization treatment and / or crosslinking treatment is carried out by heating or light irradiation.

In a preferred embodiment, the step of laminating the second birefringent layer is a step of applying a coating liquid containing a liquid crystal material and a chiral agent to a substrate, and treating the coating liquid at a temperature at which the liquid crystal material exhibits a liquid crystal phase. And forming a second birefringent layer on the substrate, and transferring the second birefringent layer formed on the substrate to the surface of the first birefringent layer. In preferable embodiment, the said coating liquid contains the said chiral agent in the ratio of 0.03-0.11 weight part with respect to 100 weight part of said liquid crystal materials. In a preferred embodiment, the substrate is a polyethylene terephthalate film obtained by performing an stretching treatment and a recrystallization treatment. In preferable embodiment, the said base material is used for the application | coating process of the said coating liquid, without performing the orientation process with respect to the surface of the said base material.

According to another further aspect of this invention, an image display apparatus is provided. This image display apparatus contains said elliptical polarizing plate.

Effects of the Invention

As mentioned above, according to this invention, by forming a 1st birefringence layer and a 2nd birefringence layer by a liquid crystal material, the difference of nx and ny can be made very large compared with the case where these are formed into a polymeric stretched film. As a result, the thickness in which the desired in-plane retardation for functioning the first birefringent layer as the lambda / 2 plate can be made significantly thinner as compared with the conventional one, and the desired in-plane retardation for the second birefringence layer to function as the lambda / 4 plate. The thickness obtained can be made significantly thin compared with the conventional one. Therefore, the elliptical polarizing plate of the present invention becomes very thin as compared with the conventional elliptical polarizing plate, and can greatly contribute to the thinning of the image display device. Moreover, since the orientation is fixed by superposing | polymerizing or crosslinking the liquid crystal material of a 1st birefringent layer and a 2nd birefringent layer, the elliptically polarizing plate of this invention has remarkably excellent heat resistance compared with the conventional elliptically polarizing plate. As a result, it has the special effect that an optical characteristic does not fall even in a high temperature environment (for example, a vehicle use).

According to the present invention, the second birefringent layer is formed with respect to the liquid crystal material by using a predetermined amount (small amount) of the chiral agent, so that the direction of the slow axis is shifted without forming the negative C plate (nx = ny> nz). can do. That is, the direction can be shifted without destroying the slow axis. As a result, the slow axis direction of the second birefringent layer can be set in a direction other than parallel or perpendicular to the absorption axis of the polarizer. Conventionally, in the elliptical polarizing plate, light leakage is prevented by shifting the slow axis direction of the λ / 4 plate from the direction parallel or perpendicular to the absorption axis of the polarizer, but such λ / 4 plate has been suggested. It was practically impossible to laminate practically (it was practically unacceptable in terms of manufacturing efficiency since the λ / 4 plate had to be punched in the oblique direction or attached with the shaft displaced). According to the present invention, a long polarizer and a long λ / 4 plate having a slow axis in a direction other than parallel or perpendicular to the absorption axis of the polarizer are aligned in the same direction (so-called roll-to-roll). by roll-to-roll). Therefore, a long λ / 4 plate having a slow axis in a direction other than parallel or perpendicular to the absorption axis of the polarizer can be laminated with very high production efficiency. As a result, an elliptically polarizing plate (previously practically impossible to manufacture) can be obtained which can significantly prevent light leakage. Conventionally, when the chiral agent is used, a negative C plate is formed and the slow axis disappears. However, it has been found that by using a small amount of the chiral agent, it can be shifted without destroying the slow axis. As described above, it is one of the great achievements of the present invention that the direction of the slow axis can be controlled by optimizing the amount of the chiral agent used.

1 is a schematic cross-sectional view of an elliptical polarizing plate according to a preferred embodiment of the present invention.

2 is an exploded perspective view of an elliptically polarizing plate according to a preferred embodiment of the present invention.

It is a perspective view which shows the outline of one process in an example of the manufacturing method of the elliptical polarizing plate of this invention.

It is a perspective view which shows the outline of the other process in an example of the manufacturing method of the elliptical polarizing plate of this invention.

It is a schematic diagram which shows the outline of another another process in an example of the manufacturing method of the elliptical polarizing plate of this invention.

It is a schematic diagram which shows the outline of another further process in an example of the manufacturing method of the elliptical polarizing plate of this invention.

It is a schematic diagram which shows the outline of another further process in an example of the manufacturing method of the elliptical polarizing plate of this invention.

8 is a schematic cross-sectional view of a liquid crystal panel used in a liquid crystal display device according to a preferred embodiment of the present invention.

It is a schematic sectional drawing explaining the orientation state of the liquid crystal molecule in VA mode.

* Explanation of symbols for the main parts of the drawings *

10: elliptical polarizer

11: polarizer

12: protective layer

13: first birefringent layer

14: second birefringent layer

15: second protective layer

20: liquid crystal cell

100: liquid crystal panel

Implement the invention  Best form for

A. Elliptical Polarizer

A-1. Overall composition of elliptical polarizer

1 is a schematic cross-sectional view of an elliptical polarizing plate according to a preferred embodiment of the present invention. FIG. 2 is an exploded perspective view illustrating an optical axis of each layer constituting the elliptical polarizing plate of FIG. 1. As shown in FIG. 1, this elliptical polarizing plate 10 has a polarizer 11, a protective layer 12 (transparent protective film), a first birefringent layer 13, and a second birefringent layer 14. Practically, the elliptically polarizing plate of the present invention may have a second protective layer 15 (transparent protective film) on the side where the protective layer 12 (transparent protective film) of the polarizer is not laminated.

The first birefringent layer 13 can function as a so-called λ / 2 plate. In the present specification, the λ / 2 plate converts linearly polarized light having a specific vibration direction into linearly polarized light having a vibration direction orthogonal to the vibration direction of the linearly polarized light, or sets right circularly polarized light to the left. ) Plate that has the function of converting circularly polarized light (or left circularly polarized light into right circularly polarized light). The second birefringent layer 14 can function as a so-called λ / 4 plate. In the present specification, the λ / 4 plate refers to a plate having a function of converting linearly polarized light of a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light).

FIG. 2 is an exploded perspective view illustrating the optical axis of each layer constituting the elliptical polarizing plate according to the preferred embodiment of the present invention. (In FIG. 2, the second protective layer 15 is omitted for ease of viewing. ). As shown in FIG. 2, the said 1st birefringent layer 13 is laminated | stacked so that the slow axis B may define predetermined angle (alpha) with respect to the absorption axis A of the polarizer 11, and the said 2nd The birefringent layer 14 is laminated so that the slow axis C defines a predetermined angle β with respect to the absorption axis A of the polarizer 11. The relationship between the angle α and the angle β is preferably 2α + 40 ° <β <2α + 50 °, more preferably 2α + 42 ° <β <2α + 48 °, particularly preferably 2α + 43 ° <β <2α + 47 °, most preferably Is β = 2α + 45 °. By having such a relationship between the angle α and the angle β, a polarizing plate having very excellent circular polarization characteristics can be obtained. Moreover, since this relationship is comprehensive, it is not necessary to examine the stacking direction by trial and error for each product. That is, by using this relationship in most combinations of polarizers, λ / 2 plates and λ / 4 plates, very excellent circular polarization characteristics can be realized. More specifically, angle (alpha) is 10 degrees-20 degrees or -10 degrees--20 degrees, Preferably it is 13 degrees-19 degrees or -13 degrees--19 degrees, More preferably, 14 degrees-18 degrees Or -14 ° to -18 °. Therefore, in the most preferable embodiment (β = 2α + 45 °), the angle β is 65 ° to 85 ° or 5 ° to 25 °, preferably 71 ° to 83 ° or 7 ° to 19 °, more preferably. Preferably it is 73 degrees-81 degrees, or 9 degrees-17 degrees. By stacking the second birefringent layer and the polarizer to form such an angle β, light leakage can be significantly prevented. It is one of the characteristics of this invention to implement | achieve the 2nd birefringent layer which prescribes the angle (beta) other than parallel (0 degrees +/- 0.5 degree) or orthogonal (90 degrees +/- 0.5 degree).

The total thickness of the elliptical polarizing plate of the present invention is preferably 80 to 200 µm, more preferably 90 to 130 µm, and most preferably 100 to 120 µm. According to the present invention, by forming the first birefringent layer and the second birefringent layer by the liquid crystal material (described later), the thickness for making the first birefringent layer function as a lambda / 2 plate can be made significantly thinner than before, and The thickness for making the second birefringent layer function as a λ / 4 plate can be significantly thinner than in the related art. As a result, the elliptical polarizing plate of the present invention can make the total thickness as thin as at least a quarter as compared with the conventional elliptical polarizing plate, and can greatly contribute to thinning of the liquid crystal display device. Hereinafter, each layer which comprises the elliptical polarizing plate of this invention is demonstrated in detail.

A-2. First birefringent layer

As described above, the first birefringent layer 13 can function as a so-called lambda / 2 plate. By the first birefringent layer functioning as a λ / 2 plate, the phase difference can be appropriately adjusted with respect to the wavelength dispersion characteristic (particularly, the wavelength range in which the phase difference deviates from λ / 4) of the second birefringent layer functioning as the λ / 4 plate. . The in-plane retardation Δnd of the first birefringent layer is preferably 210 to 330 nm, more preferably 230 to 310 nm, and most preferably 245 to 295 nm at a wavelength of 590 nm. Moreover, in-plane phase difference (DELTA) nd is calculated | required from Formula (DELTA) nd = (nx-ny) xd. Here, nx is a refractive index of the direction in which the in-plane refractive index becomes largest (that is, the slow axis direction), and ny is the refractive index of the direction perpendicular to a slow axis in surface. d is the thickness of the first birefringent layer. The first birefringent layer 13 preferably has a refractive index distribution of nx> ny = nz. In this specification, "ny = nz" includes not only the case where ny and nz are exactly the same, but also the case where ny and nz are substantially the same. In this specification, "it is substantially the same" means including the case where nx and ny differ in the range which does not affect practically the polarization characteristic of an elliptically polarizing plate practically.

The thickness of the first birefringent layer may be set to function most appropriately as a λ / 2 plate. In other words, the thickness can be set such that a desired in-plane retardation is obtained. Specifically, the thickness is preferably 0.5 to 5 µm, more preferably 1 to 4 µm, and most preferably 1.5 to 3 µm.

As a material which forms a said 1st birefringence layer, arbitrary appropriate materials can be employ | adopted as long as the above-mentioned characteristic is acquired. A liquid crystal material is preferable, and a liquid crystal material (nematic liquid crystal) whose liquid crystal phase is a nematic phase is more preferable. As such a liquid crystal material, a liquid crystal polymer or a liquid crystal monomer can be used, for example. The liquid crystalline expression mechanism of the liquid crystal material may be lyotropic, thermotropic, or both. Moreover, it is preferable that the orientation state of a liquid crystal is homogeneous orientation.

When the said liquid crystal material is a liquid crystal monomer, it is preferable that it is a polymerizable monomer or a crosslinkable monomer, for example. This is because, as will be described later, the alignment state of the liquid crystal material can be fixed by polymerizing or crosslinking the polymerizable monomer or the crosslinkable monomer. After orienting a liquid crystal monomer, if the liquid crystal monomer (polymerizable monomer or crosslinkable monomer) is polymerized or bridge | crosslinked, for example, the said orientation state can be fixed by it. Here, a polymer is formed by polymerization and a three-dimensional network structure is formed by crosslinking, which are non-liquid crystalline. Therefore, in the formed first birefringent layer, the transition to the liquid crystal phase, the glass phase, and the crystal phase due to the temperature change peculiar to the liquid crystal compound does not occur, for example. As a result, the first birefringent layer becomes a birefringent layer having excellent stability which is not influenced by temperature change.

Arbitrary appropriate liquid crystal monomers can be employ | adopted as the said liquid crystal monomer. For example, the polymerizable mesogenic compounds described in Japanese Patent Laid-Open Publication No. 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, GB2280445 and the like can be used. have. As a specific example of such a polymerizable mesogen compound, BASF trade name LC242, Merck trade name E7, and Wacker-Chem trade name LC-Sillicon-CC3767 are mentioned, for example.

As said liquid crystal monomer, a nematic liquid crystal monomer is preferable, for example, The monomer represented by following formula (1) is mentioned specifically ,. These liquid crystal monomers may be used alone or in combination of two or more thereof.

[Formula 4]

In said Formula (1), A <^1> and A <^2> represent a polymeric group, respectively, and may be same or different. In addition, either one of A <^1> and A <^2> may be hydrogen. Each X independently represents a single bond, -O-, -S-, -C = N-, -O-CO-, -CO-O-, -O-CO-O-, -CO-NR-, -NR-CO-, -NR-, -O-CO-NR-, -NR-CO-O-, -CH ₂ -O- or -NR-CO-NR, R represents H or C ₁ -C ₄ alkyl and M represents a mesogenic group.

In said Formula (1), although X may be same or different, it is preferable that it is the same.

Also in the monomer of the said Formula (1), it is preferable that A <^2> is arrange | positioned with respect to A <^1> , respectively.

Moreover, it is preferable that A <^1> and A <^2> respectively independently represent following formula (2), and it is preferable that A <^1> and A <^2> are the same group.

ZX- (Sp) _n ... (2)

In the formula (2), Z represents a crosslinkable group, X is as defined in the formula (1), and Sp is a spacer composed of a linear or branched substituted or unsubstituted alkyl group having 1 to 30 carbon atoms. N represents 0 or 1; Carbon chain in the Sp, for example may be alkyl of oxygen in ether functional group, sulfur in a thioether functional group, a non-adjacent imino or C ₁ ~C ₄ is already involved by group.

In said Formula (2), it is preferable that Z is either of the atomic groups represented by a following formula. In the following formulae, examples of R include groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl and t-butyl.

[Formula 5]

In Formula (2), Sp is preferably any one of atomic groups represented by the following formula, and m is preferably 1 to 3 and p is 1 to 12 in the following formula.

[Formula 6]

In said Formula (1), it is preferable that M is represented by following formula (3). In following formula (3), X is the same as what was defined by said formula (1). Q represents a substituted or unsubstituted linear or branched alkylene or aromatic hydrocarbon atom group, for example. Q may be, for example, substituted or unsubstituted straight or branched C _{1 to} C ₁₂ alkylene.

[Formula 7]

When Q is an aromatic hydrocarbon atom group, for example, atom groups as shown in the following formulas and their substituted analogs are preferable.

[Formula 8]

As a substituted analog of the aromatic hydrocarbon atom group shown by the said formula, you may have 1-4 substituents per aromatic ring, for example, and you may have 1 or 2 substituents per aromatic ring or group. The substituents may be the same or different. As the substituent, for example, there may be mentioned a C ₁ ~C ₄ alkyl, nitro, F, Cl, Br, halogen, phenyl, such as I, C ₁ ~C ₄ alkoxy and the like.

As a specific example of the said liquid crystal monomer, the monomer represented by following formula (4)-(19) is mentioned, for example.

[Formula 9]

The temperature range in which the said liquid crystal monomer shows liquid crystallinity differs according to the kind. Specifically, the temperature range is preferably 40 to 120 ° C, more preferably 50 to 100 ° C, and most preferably 60 to 90 ° C.

A-3. Second birefringent layer

As described above, the second birefringent layer 14 can function as a so-called? / 4 plate. According to the present invention, the circularly polarized light function in a wide wavelength range is corrected by correcting the wavelength dispersion characteristic of the second birefringent layer serving as the λ / 4 plate by the optical characteristic of the first birefringent layer serving as the λ / 2 plate. Can exert. The in-plane retardation Δnd of the second birefringent layer is preferably 80 to 200 nm, more preferably 100 to 180 nm, and most preferably 120 to 160 nm at a wavelength of 590 nm. Nz coefficient (= (nx-nz) / (nx-ny)) of a 2nd birefringence layer becomes like this. Preferably it is 1.0-1.5, More preferably, it is 1.2-1.3. Moreover, it is preferable that the said 2nd birefringent layer 14 has refractive index distribution of nx> ny> nz.

The thickness of the second birefringent layer may be set to function most appropriately as a λ / 4 plate. In other words, the thickness can be set such that a desired in-plane retardation is obtained. Specifically, the thickness is preferably 0.3 to 3 µm, more preferably 0.5 to 2.5 µm, and most preferably 0.8 to 2 µm. One of the features of the present invention is to realize such a very thin second birefringent layer (λ / 4 plate). For example, while the thickness of the lambda / 4 plate by the conventional stretched film is about 60㎛, according to the elliptical polarizing plate of the present invention, lambda / 4 plate having a thickness of about 1/20 ~ 1/200 2 birefringence layer) is feasible.

As a material which forms a said 2nd birefringence layer, arbitrary appropriate materials can be employ | adopted as long as the above-mentioned characteristic is obtained. Preferably, the second birefringent layer is formed from a liquid crystal composition containing a liquid crystal material and a chiral agent. By using the liquid crystal material, since the difference between nx and ny can be made remarkably large compared with the conventional polymer stretched film (for example, norbornene-type resin, polycarbonate resin), a desired in-plane phase difference can be obtained in a (lambda) / 4 plate. Can make the thickness significantly thinner. And by using a predetermined amount of chiral agents together, the slow axis of the 2nd birefringent layer obtained can be changed to a desired direction. Both the liquid crystal material and the chiral agent may be used alone or in combination of two or more thereof.

As the liquid crystal material, the same material as that used for the first birefringent layer can be used. Details of the liquid crystal material are as described in the above section A-2.

As said chiral agent, arbitrary suitable materials which can orientate a liquid crystal material to a desired direction, and express the slow axis of a 2nd birefringent layer in a desired direction can be employ | adopted. For example, the torsional force of such chiral agent is preferably 1 × 10 ⁻⁶ nm ⁻¹ · (wt%) ⁻¹ or more, more preferably 1 × 10 ⁻⁵ nm ⁻¹ · (wt%) ^{-1 to} 1 x 10 ^-2 nm ^-1 (wt%) ^{- 1} , most preferably 1 x 10 ^-4 nm ^-1 (wt%) ^{-1 to} 1 x 10 ^-3 nm ^-1 wt%) ^{- 1} . By using a predetermined amount of the chiral agent having such a torsional force, the slow axis of the second birefringent layer can be expressed in a desired direction. In addition, in this specification, a "torsional force" means the ability which a chiral agent gives a twist to a liquid-crystal material, and shifts the slow axis of a 2nd birefringence layer.

The chiral agent is preferably a polymerizable chiral agent. As a specific example of a polymeric chiral agent, the chiral compound represented by following General formula (20)-(23) is mentioned.

In the formulas (20) to (23), Z and Sp are as defined in the formula (2), and X ² , X ³ and X ⁴ are each independently a chemical single bond, -O-, -S- , -O-CO-, -CO-O-, -O-CO-O-, -CO-NR-, -NR-CO-, -O-CO-NR-, -NR-CO-O-,- represents a NR-CO-NR-, R shows a ~C ₄ alkyl, H, C _1. In addition, X ⁵ is a chemical single bond, -O-, -S-, -O-CO-, -CO-O-, -O-CO-O-, -CO-NR-, -NR-CO-, -O-CO-NR-, -NR-CO-O-, -NR-CO-NR, -CH ₂ O-, -O-CH _2- , -CH = N-, -N = CH- or -N ≡N-. R is the same as above, represents a ~C ₄ alkyl, H, C _1. M represents a mesogenic group in the same manner as described above, and P ¹ is hydrogen, a C ₁ -C ₃₀ alkyl group substituted with _{1 to} 3 C ₁ -C ₆ alkyl, a C ₁ -C ₃₀ acyl group, or C _3- C ₈ cycloalkyl group is represented and n is an integer of 1-6. Ch represents an n-valent chiral group. In the formula (23), at least one of X ³ and X ⁴ is -O-CO-O-, -O-CO-NR-, -NR-CO-O-, or -NR-CO-NR-. It is preferable. In the above formula (22), when P ¹ is an alkyl group, an acyl group or a cycloalkyl group, for example, the carbon chain thereof is oxygen in an ether functional group, sulfur in a thioether functional group, nonadjacent imino group or C _1. It may be interrupted by a -C ₄ alkylimino group.

As a chiral group represented by said Ch, the atomic group shown by following formula is mentioned, for example.

[Formula 10]

[Formula 11]

In the atomic group, L represents C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, halogen, COOR, OCOR, CONHR or NHCOR, and R represents C ₁ -C ₄ alkyl. In addition, the terminal in the atom group shown by the said formula represents the number of bond with the adjacent group.

Among the above atomic groups, the atomic groups represented by the following formulas are particularly preferable.

[Formula 12]

Also, the chiral compound represented by the formula (21) or (23), for example, n is 2, Z is H ₂ C = CH-, it is preferred Ch is an atomic group represented by the following formula.

[Formula 13]

As a specific example of the said chiral compound, the compound represented by following formula (24)-(44) is mentioned, for example. Moreover, these chiral compounds have a torsional force of 1 * 10 <^-6> nm <^-1> (wt%) <^-1> or more.

[Formula 14]

[Formula 15]

In addition to the chiral compounds as described above, for example, the chiral compounds described in RE-A4342280 and German Patent Application Nos. 19520660.6 and 19520704.1 can be preferably used.

Moreover, as a combination of the said liquid crystal material and the said chiral agent, arbitrary appropriate combinations can be employ | adopted according to the objective. As a particularly preferable combination, the combination of the liquid crystal monomer of the said Formula (10) / chiral agent of the said Formula (32), the combination of the liquid crystal monomer of the said Formula (10) / chiral agent of the said Formula (38), said formula ( The liquid crystal monomer agent of 11) / the combination of the chiral agent of the said Formula (39), etc. are mentioned.

The chiral agent may be used in an amount of preferably 0.03 to 0.11 part by weight, more preferably 0.045 to 0.105 part by weight, and most preferably 0.05 to 0.09 part by weight based on 100 parts by weight of the liquid crystal material. When the usage-amount of a chiral agent is less than 0.03 weight part, torsion is not fully provided to a liquid crystal material, and the slow axis of a 2nd birefringence layer may not shift | deviate enough. When the usage-amount of a chiral agent exceeds 0.11 weight part, a liquid crystalline material may be cholesterically oriented and a negative C plate (nx = ny> nz) may be formed. As a result, the slow axis may not be formed in the second birefringent layer. It is one of the features of the present invention to realize that the slow axis is shifted without forming a negative C plate by adjusting the amount of the chiral agent used in such a range.

The said liquid crystal composition further contains at least one of a polymerization initiator and a crosslinking agent (curing agent) as needed. By using a polymerization initiator and / or a crosslinking agent (curing agent), the deviation which the liquid crystal material formed in the liquid crystal state can be fixed. As a result, in the second birefringent layer, the slow axis shifted in the desired direction can be stably formed. As such a polymerization initiator or a crosslinking agent, arbitrary appropriate substances can be adopted as long as the effect of this invention is acquired. As a polymerization initiator, benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN) are mentioned, for example. As a crosslinking agent (curing agent), an ultraviolet curing agent, a photocuring agent, a thermosetting agent is mentioned, for example. More specifically, an isocyanate crosslinking agent, an epoxy crosslinking agent, a metal chelate crosslinking agent, etc. are mentioned. These can be used individually or can be used in combination of 2 or more type. Content of the polymerization initiator or crosslinking agent in a liquid crystal composition becomes like this. Preferably it is 0.1-10 weight%, More preferably, it is 0.5-8 weight%, Most preferably, it is 1-5 weight%. When content is less than 0.1 weight%, it may become inadequate to fix the shift | offset | difference of a liquid crystal material. When content exceeds 10 weight%, since the temperature range which the said liquid crystal material shows a liquid crystal state becomes narrow, temperature control at the time of forming a 2nd birefringent layer may become difficult.

The said liquid crystal composition can further contain arbitrary appropriate additives as needed. Examples of the additive include anti-aging agents, modifiers, surfactants, dyes, pigments, discoloration inhibitors, ultraviolet absorbers, and the like. These additives can be used individually or can be used in combination of 2 or more type. More specifically, examples of the anti-aging agent include phenolic compounds, amine compounds, organosulfur compounds, and phosphine compounds. As said modifier, glycols, silicones, and alcohols are mentioned, for example. The said surfactant is added, for example in order to smooth the surface of a birefringent layer, For example, silicone type, acryl type, and fluorine type surfactant can be used, A silicone type surfactant is especially preferable.

A-4. Polarizer

As the polarizer 11, any appropriate polarizer can be adopted according to the purpose. For example, a biaxial substance such as iodine or dichroic dye is adsorbed onto hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymerized partial saponified films. And polyene oriented films such as stretched, dehydrated polyvinyl alcohol and dehydrochloric acid polyvinyl chloride. Especially, the polarizer which uniaxially stretched by adsorb | sucking dichroic substances, such as a polyvinyl alcohol-type film and iodine, is especially preferable because it has a high polarization dichroic ratio. Although the thickness in particular of these polarizers is not restrict | limited, Usually, it is about 1-80 micrometers.

The polarizer which uniaxially stretched by adsorbing iodine to a polyvinyl alcohol-type film, for example, can be produced by dyeing polyvinyl alcohol by dipping in an aqueous solution of iodine, and stretching the film to 3 to 7 times its original length. As needed, you may contain boric acid, zinc sulfate, zinc chloride, etc., and can also be immersed in aqueous solution, such as potassium iodide. If necessary, the polyvinyl alcohol-based film may be dipped in water and washed with water before dyeing.

By washing the polyvinyl alcohol-based film with water, it is possible not only to clean the contamination or blocking blocking agent on the surface of the polyvinyl alcohol-based film, but also to swell the polyvinyl alcohol-based film to prevent unevenness such as uneven dyeing. Stretching may be performed after dyeing with iodine, or may be performed while dyeing, or may be dyed with iodine after stretching. It can extend | stretch also in aqueous solution, such as a boric acid and potassium iodide, or in a water bath.

A-5. Protective layer

The said protective layer 12 and the 2nd protective layer 15 consist of arbitrary suitable films which can be used as a protective film of a polarizing plate. Preferably it is a transparent protective film. As a specific example of the material used as a main component of such a film, cellulose resins, such as triacetyl cellulose (TAC), polyester type, polyvinyl alcohol type, polycarbonate type, polyamide type, polyimide type, polyether sulfide Transparent resins, such as a phone type, a polysulfone type, a polystyrene type, a polynorbornene type, a polyolefin type, an acryl type, an acetate type, etc. are mentioned. Moreover, thermosetting resins, such as an acryl-type, urethane type, an acryl urethane type, an epoxy type, a silicone type, or ultraviolet curable resin, etc. are mentioned. In addition, glassy polymers, such as a siloxane polymer, are mentioned, for example. Moreover, the polymer film of Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) can also be used. As a material of this film, the resin composition containing the thermoplastic resin which has a substituted or unsubstituted imide group in a side chain, and the thermoplastic resin which has a substituted or unsubstituted phenyl group and a nitrile group in a side chain can be used, for example, For example, the resin composition which has the alternating copolymer which consists of isobutene and N-methyl maleimide, and an acrylonitrile styrene copolymer is mentioned. The polymer film may be, for example, an extrusion molded product of the resin composition. TAC, polyimide resin, polyvinyl alcohol resin, and glassy polymer are preferable, and TAC is more preferable.

It is preferable that the said protective layer is transparent and is not colored. Specifically, the phase difference value Rth in the thickness direction is preferably -90 nm to +90 nm, more preferably -80 nm to +80 nm, and most preferably -70 nm to +70 nm. Thickness direction retardation Rth is calculated | required by Formula: Rth = {(nx + ny) / 2-nz} xd, when d (nm) is made into the thickness of a film (layer).

As thickness of the said protective layer, arbitrary appropriate thickness can be employ | adopted as long as the phase difference of the said preferable thickness direction is obtained. Specifically, the thickness of the protective layer is preferably 5 mm or less, more preferably 1 mm or less, particularly preferably 1 to 500 µm, and most preferably 5 to 150 µm.

On the surface opposite to the polarizer of the second protective layer 15 (that is, the outermost part of the elliptical polarizing plate), a hard coat treatment, an antireflection treatment, an anti-sticking treatment, an antiglare treatment, or the like can be performed as necessary.

B. Manufacturing Method of Elliptical Polarizer

The manufacturing method of the elliptical polarizing plate in preferable embodiment of this invention is a process of performing an orientation process on the surface of a transparent protective film (T: finally becomes protective layer 12); Forming a first birefringent layer on the surface on which the alignment treatment of the transparent protective film (T) has been performed; Laminating the polarizer on the surface of the transparent protective film T, wherein the polarizer and the first birefringent layer are disposed on opposite sides with the transparent protective film T interposed therebetween, and the surface of the first birefringent layer The step of laminating a second birefringent layer is included. According to such a manufacturing method, the elliptical polarizing plate as shown, for example in FIG. 1 and FIG. 2 is obtained. The film to which the order and / or orientation process of each process mentioned above is given may be changed suitably according to the objective. For example, the laminating step of the polarizer may be carried out after the forming step or laminating step of any of the birefringent layers. For example, an orientation process may be performed to the transparent protective film (T), and may be performed to arbitrary appropriate base materials. When the substrate is subjected to an orientation treatment, the film (specifically, the first birefringent layer) formed on the substrate can be transferred (laminated) in an appropriate order according to the desired laminated structure of the elliptical polarizing plate. Hereinafter, each process is explained in full detail.

B-1. Orientation Treatment of Transparent Protective Film

A polarizer (as shown in FIG. 2) by performing an orientation treatment on the surface of the transparent protective film (T: finally becomes the protective layer 12) and applying a coating liquid containing a predetermined liquid crystal material to the surface. It is possible to form the first birefringent layer 13 having the slow axis B forming the angle α with respect to the absorption axis of 11) (the process of forming the first birefringent layer will be described later).

Arbitrary appropriate orientation treatment can be employ | adopted as an orientation treatment with respect to the said transparent protective film (T). As a specific example, the rubbing process, the evaporation method, the extending | stretching process, the photo-alignment process, the magnetic field orientation process, the electric field orientation process, etc. are mentioned. Preferably, it is a rubbing process. Moreover, the processing conditions of various orientation treatment can employ | adopt arbitrary appropriate conditions according to the objective.

The orientation direction of the said orientation process is a direction which forms a predetermined angle with the absorption axis of a polarizer when the transparent protective film (T) and a polarizer are laminated | stacked. This orientation direction is substantially the same as the slow axis B direction of the 1st birefringent layer 13 formed so that it may mention later. Therefore, the said predetermined angle is 10 degrees-20 degrees or -10 degrees--20 degrees, Preferably it is 13 degrees-19 degrees or -13 degrees--19 degrees, More preferably, 14 degrees-18 degrees or It is -14 degrees--18 degrees.

As an orientation treatment which can define the predetermined angle as mentioned above with respect to a long transparent protective film T, performing a process in the longitudinal direction of a long transparent protective film T, and a long transparent protection It is mentioned to process in the inclination direction (specifically, the direction which prescribes predetermined angle as mentioned above) with respect to the longitudinal direction of the film T or its vertical direction (width direction). The polarizer is produced by stretching a polymer film dyed with a dichroic substance as described above, and has an absorption axis in the stretching direction. And when mass-producing a polarizer, a long polymer film is prepared and extending | stretching is continuously performed in the longitudinal direction. Therefore, when attaching a long polarizer and a long transparent protective film T, the longitudinal direction of both becomes the absorption axis direction of a polarizer. For this reason, in order to orientate in the direction which forms a predetermined angle with respect to the absorption axis of a polarizer, it is preferable to perform an orientation process in a diagonal direction. Since the absorption axis direction of the polarizer and the longitudinal direction of the elongate film (polarizer and transparent protective film T) substantially correspond, the direction of orientation treatment may be performed in the direction which forms said predetermined angle with respect to a longitudinal direction. On the other hand, when performing a process in the longitudinal direction or the width direction of a transparent protective film, it is necessary to laminate | stack after cutting a transparent protective film in diagonal direction. As a result, there is a possibility that the angle of the optical axis may vary in each cut out film, and as a result, there may be a difference in quality between products, resulting in cost and time, increased waste, and difficulty in producing a large film. .

An orientation treatment may be performed directly on the transparent protective film (T) surface, may form an arbitrary appropriate orientation layer (typically a polyimide layer or a polyvinyl alcohol layer), and may perform it to the said orientation layer.

B-2. Coating process of liquid crystal material which forms a 1st birefringent layer

Next, on the surface of the transparent protective film (T) which performed the said orientation treatment, said A-2. The coating liquid containing the liquid crystal material described in the section is coated, and then the liquid crystal material is oriented to form the first birefringent layer. Specifically, what is necessary is just to prepare the coating liquid which melt | dissolved or disperse | distributed the liquid crystal material in the appropriate solvent, and apply | coat this coating liquid to the surface of the transparent protective film (T) to which the said orientation process was given. The alignment process of the liquid crystal material is described later in B-3. It is explained in section.

As the solvent, any suitable solvent capable of dissolving or dispersing the liquid crystal material can be employed. The kind of solvent used can be suitably selected according to the kind etc. of liquid crystal material. Specific examples of the solvent include halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, methylene chloride, trichloroethylene, tetrachloroethylene, chlorobenzene, and orthodichlorobenzene, phenol, p Phenols such as -chlorophenol, o-chlorophenol, m-cresol, o-cresol, and p-cresol, aromatics such as benzene, toluene, xylene, mesitylene, methoxybenzene, and 1,2-dimethoxybenzene Ketone solvents such as hydrocarbons, acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, and N-methyl-2-pyrrolidone, ethyl acetate, Ester solvents such as butyl acetate and propyl acetate, t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol And alcohol solvents such as 2-methyl-2,4-pentanediol, amide solvents such as dimethylformamide and dimethylacetamide, nitrile solvents such as acetonitrile and butyronitrile, diethyl ether and dibutyl ether Ether solvents such as tetrahydrofuran, dioxane, or carbon disulfide, ethyl cellosolve, butyl cellosolve, ethyl cellosolve acetate, and the like. Preferably, toluene, xylene, mesitylene, MEK, methyl isobutyl ketone, cyclohexanone, ethyl cellosolve, butyl cellosolve, ethyl acetate, butyl acetate, propyl acetate, and ethyl cellosolve acetate. These solvents may be used alone or in combination of two or more thereof.

Content of the liquid crystal material in the said coating liquid can be suitably set according to the kind of liquid crystal material, the thickness of the layer made into the objective, etc. Specifically, the content of the liquid crystal material is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, and most preferably 15 to 30% by weight.

The said coating liquid can further contain arbitrary appropriate additives as needed. Specific examples of the additives include a polymerization initiator and a crosslinking agent. These are especially preferably used when a liquid crystal monomer (polymerizable monomer or crosslinkable monomer) is used as the liquid crystal material. Details of the polymerization initiator and the crosslinking agent are described in the above section A-3. It is as described in the term.

The coating amount of the coating liquid may be appropriately set depending on the concentration of the coating liquid, the thickness of the target layer, and the like. For example, when the liquid crystal material concentration of the coating liquid is 20% by weight, the coating amount is preferably 0.03 to 0.17 ml, more preferably 0.05 to 0.15 ml per area (100 cm 2) of the transparent protective film T. Most preferably, it is 0.08-0.12 ml.

Arbitrary appropriate methods can be employ | adopted as a coating method. As a specific example, the roll coating method, the spin coating method, the wire bar coating method, the dip coating method, the extrusion method, the curtain coating method, the spray coating method, etc. are mentioned.

B-3. Alignment process of the liquid crystal material which forms a 1st birefringent layer

Next, the liquid crystal material which forms a 1st birefringent layer is orientated according to the orientation direction of the said transparent protective film (T) surface. The alignment of the liquid crystal material is performed by treating at a temperature that shows a liquid crystal phase depending on the type of liquid crystal material used. By performing such temperature processing, a liquid crystal material takes a liquid crystal state, and the said liquid crystal material is orientated according to the orientation direction of the said transparent protective film (T) surface. Thereby, birefringence arises in the layer formed by application | coating, and a 1st birefringence layer is formed.

As described above, the treatment temperature may be appropriately determined depending on the type of liquid crystal material. Specifically, processing temperature becomes like this. Preferably it is 40-120 degreeC, More preferably, it is 50-100 degreeC, Most preferably, it is 60-90 degreeC. Moreover, processing time becomes like this. Preferably it is 30 second or more, More preferably, it is 1 minute or more, Especially preferably, it is 2 minutes or more, Most preferably, it is 4 minutes or more. When the processing time is less than 30 seconds, the liquid crystal material may not sufficiently take the liquid crystal state. On the other hand, the treatment time is preferably 10 minutes or less, more preferably 8 minutes or less, and most preferably 7 minutes or less. If the treatment time exceeds 10 minutes, the additive may be sublimated.

Moreover, as said liquid crystal material, said A-2. When using the liquid crystal monomer (polymerizable monomer and crosslinkable monomer) of description, it is preferable to perform a polymerization process or a crosslinking process further to the layer formed by the said application | coating. By performing a polymerization process, the liquid crystal monomer is polymerized, and the liquid crystal monomer is fixed as a repeating unit of the polymer molecule. Moreover, by performing a crosslinking process, the said liquid crystal monomer forms a three-dimensional network structure, and a liquid crystal monomer is fixed as part of a crosslinked structure. As a result, the alignment state of the liquid crystal material is fixed. Moreover, the polymer or three-dimensional network structure formed by superposing | polymerizing or bridge | crosslinking a liquid crystal monomer is "non-liquid crystalline". Therefore, the formed first birefringent layer does not cause a transition to a liquid crystal phase, a glass phase, or a crystal phase due to, for example, a temperature change peculiar to liquid crystal molecules. As a result, it is possible to obtain a first birefringent layer having very excellent stability which is not affected by temperature.

The specific order of the said polymerization process or crosslinking process can be suitably selected according to the kind of polymerization initiator and crosslinking agent to be used. For example, when using a photoinitiator or a photocrosslinking agent, light irradiation may be performed, In the case of using an ultraviolet polymerization initiator or an ultraviolet crosslinking agent, ultraviolet irradiation may be performed, and when using a thermal polymerization initiator or a crosslinking agent, Just heat it up. Irradiation time, irradiation intensity, total irradiation amount, etc. of light or an ultraviolet-ray can be suitably set according to the kind of liquid crystal material, the kind of transparent protective film (T), the kind of orientation treatment, the characteristic desired by a 1st birefringence layer, etc. Similarly, heating temperature, heating time, etc. can also be set suitably.

Since the liquid crystal material is oriented according to the alignment direction of the transparent protective film T by performing the above-described alignment treatment, the slow axis B of the formed first birefringent layer is aligned of the transparent protective film T. Substantially the same as the direction. Therefore, the slow axis (B) direction of the first birefringent layer is 10 ° to 20 ° or −10 ° to −20 ° with respect to the longitudinal direction of the transparent protective film T, preferably 13 ° to 19 ° or −. 13 degrees--19 degrees, More preferably, they are 14 degrees-18 degrees, or -14 degrees--18 degrees.

B-4. Lamination process of polarizer

The polarizer is laminated on the surface of the transparent protective film T. As described above, the polarizer can be laminated at any suitable time in the production method of the present invention. For example, the polarizer may be laminated on the transparent protective film T in advance, may be laminated after the first birefringent layer is formed, or may be laminated after the second birefringent layer is formed.

Arbitrary suitable lamination methods (for example, adhesion | attachment) can be employ | adopted as the lamination method of the said transparent protective film T and a polarizer. Adhesion can be performed using arbitrary appropriate adhesives or adhesives. The kind of adhesive or pressure-sensitive adhesive may be appropriately selected according to the kind of adherend (that is, transparent protective film (T) and polarizer). Specific examples of the adhesive include polymer adhesives such as acrylic, vinyl alcohol, silicone, polyester, polyurethane and polyether, isocyanate adhesives and rubber adhesives. Specific examples of the pressure-sensitive adhesives include pressure-sensitive adhesives such as acrylic, vinyl alcohol, silicone, polyester, polyurethane, polyether, isocyanate and rubber.

The thickness of the adhesive or pressure-sensitive adhesive is not particularly limited, preferably 10 to 200 nm, more preferably 30 to 180 nm, and most preferably 50 to 150 nm.

According to the manufacturing method of this invention, since the slow axis of a 1st birefringent layer can be set in the orientation process of the said transparent protective film T, the long polarization extended in the longitudinal direction (that is, having an absorption axis in a longitudinal direction) is long. Films (polarizers) can be used. That is, the elongate transparent protective film T and the elongate polarizing film (polarizer) which were orientated so as to make a predetermined angle with respect to the longitudinal direction can be continuously bonded to each other in the same direction (so-called roll-to-roll). Can be. Therefore, an elliptical polarizing plate is obtained by very excellent manufacturing efficiency. And according to this method, it is not necessary to cut | stack and laminate | stack a film obliquely with respect to the longitudinal direction (stretching direction). As a result, a deviation does not arise in the angle of an optical axis in each cut out film, As a result, the elliptical polarizing plate which does not have the quality deviation between products is obtained. In addition, since no waste due to cutting is generated, an elliptical polarizing plate can be obtained at low cost. In addition to this, manufacture of a large polarizing plate also becomes easy.

Moreover, the absorption axis direction of a polarizer is substantially parallel to the longitudinal direction of a long film. In the present specification, "substantially parallel" means that the angle in the longitudinal direction and the absorption axis direction includes 0 ° ± 10 °, preferably 0 ° ± 5 °, more preferably 0 ° ± 3 ° to be.

B-5. Lamination process of the second birefringent layer

Then, a second birefringent layer is laminated on the surface of the first birefringent layer. The detailed procedure of the lamination process of a 2nd birefringence layer is as follows. First, the coating liquid containing the liquid crystal composition (containing the liquid crystal material and the chiral agent) forming the second birefringent layer is applied to the substrate, and the liquid crystal material in the liquid crystal composition is oriented on the substrate. The said liquid crystal material is oriented by processing at the temperature which shows a liquid crystal phase according to the kind of liquid crystal material used. By performing such temperature processing, a liquid crystal material takes a liquid crystal state, and the said liquid crystal material orientates according to the orientation direction of the said base material surface. Thereby, birefringence arises in the layer formed by application | coating, and a 2nd birefringence layer is formed. In addition, since the liquid crystal material is twisted properly by the effect of the chiral agent in the liquid crystal composition, the second birefringent layer obtained has a slow axis twisted in a desired direction. Details of the coating of the coating liquid and the alignment treatment of the liquid crystal material are described in the above B-2. And B-3. As described in the section. However, since the thickness of the second birefringent layer is approximately half of the first birefringent layer, the coating amount is also about half. Specifically, the coating amount is preferably 0.02 to 0.08 ml, more preferably 0.03 to 0.07 ml, and most preferably 0.04 to 0.06 ml per area (100 cm 2) of the substrate.

As the substrate, any appropriate substrate can be used as long as a suitable second birefringent layer is obtained in the present invention. Preferably, the base material is a polyethylene terephthalate (PET) film obtained by performing an stretching treatment and a recrystallization treatment. More specifically, a base material is obtained by extrusion film molding of PET resin, extending | stretching, and then recrystallizing. As for the extending | stretching method, transverse uniaxial stretching and longitudinal and biaxial stretching are preferable. In longitudinal and biaxial stretching, the stretching ratio in the lateral direction is preferably larger than the stretching ratio in the longitudinal direction. By this method, the base material which has an orientation axis in the width direction can be obtained. In addition, you may extend | stretch a base material after forming a polyimide layer and a polyvinyl alcohol layer. The stretching temperature is preferably 120 to 160 ° C. The draw ratio is preferably 2 to 7 times. The stretching direction may be set according to the direction of the desired slow axis in the second birefringent layer. In this invention, it is preferable to shift the slow axis of a 2nd birefringence layer to directions other than parallel or perpendicular to the absorption axis (longitudinal direction of a elongate film) of a polarizer. Here, as described above, since the slow axis direction of the second birefringent layer can be controlled by changing the amount of the chiral agent used in a predetermined range, the stretching of the base material is in the transverse direction (direction perpendicular to the length direction: In the direction orthogonal to the absorption axis of the polarizer). As described above, in the present invention, it is not necessary to punch in order to match the slow axis direction of the second birefringent layer, and adhesion by roll-to-roll becomes possible, and manufacturing efficiency is further improved. Recrystallization temperature becomes like this. Preferably it is 150-250 degreeC. By recrystallization in such a temperature range, the direction of PET molecules becomes more uniform, and the base material with a very small deviation of an orientation axis can be obtained. The thickness of the substrate is preferably 20 to 100 µm, more preferably 30 to 90 µm, and most preferably 30 to 80 µm. By having the thickness of such a range, the intensity | strength which supports a very thin 2nd birefringence layer favorably in a lamination process is provided, and also operability, such as slipperiness | lubricacy and roll running property, is maintained suitably.

As described above, by performing the combination of the specific stretching treatment and the recrystallization treatment, a substrate having a very small variation in the orientation axis can be obtained. Specifically, the deviation of the orientation axis of the substrate to be obtained is preferably within ± 1 ° with respect to the average direction of the orientation axis, and more preferably within ± 0.5 °. By using such a base material, the orientation treatment (for example, a rubbing process, an evaporation process, an extending | stretching process, a photo-alignment process, a magnetic field orientation process, an electric field orientation process) with respect to a base material surface can be skipped when apply | coating a liquid crystal composition. As a result, it becomes possible to manufacture a very thin elliptical polarizing plate with extremely excellent production efficiency. It is one of the big features of this invention that the 2nd birefringent layer was formed using the base material which can omit an orientation process. Moreover, such a base material is available from Toray Corporation and Mitsubishi Polyester Corporation.

Next, the second birefringent layer formed on the substrate is transferred to the surface of the first birefringent layer. The transfer method is not particularly limited, and transfer is performed by, for example, attaching the second birefringent layer supported on the substrate to the first birefringent layer via an adhesive. As said adhesive agent, a curable adhesive agent is mentioned typically. Typical examples of the curable adhesive include photocurable adhesives such as ultraviolet curable adhesives, moisture curable adhesives, and thermosetting adhesives. As a specific example of a thermosetting adhesive agent, thermosetting resin adhesives, such as an epoxy resin, an isocyanate resin, and a polyimide resin, are mentioned. As an example of a moisture hardening type adhesive agent, the moisture hardening type adhesive agent of an isocyanate resin type is mentioned. Moisture-curable adhesives (especially moisture-curable adhesives of isocyanate resins) are preferred. Since the moisture-curable adhesive is cured by reacting with moisture in the air, adsorbed water on the surface of the adherend, active hydrogen groups such as hydroxyl groups and carboxyl groups, and the like, the moisture-curable adhesive can be cured naturally by leaving the adhesive after application and excellent in operability. And since there is no need to heat for curing, the first and second birefringent layers are not heated at the time of adhesion (adhesion). As a result, there is no fear of heat shrink, and even when the first and second birefringent layers are very thin as in the present invention, cracks and the like during lamination can be significantly prevented. In addition, the said isocyanate resin adhesive is a generic term of a polyisocyanate adhesive and a polyurethane resin adhesive.

A commercially available adhesive may be used for the said curable adhesive, for example, may melt | dissolve or disperse said various curable resin in a solvent, and may prepare it as a curable resin adhesive solution (or dispersion liquid). When preparing a solution (or dispersion), the content ratio of the curable resin in the solution is preferably 10 to 80% by weight, more preferably 20 to 65% by weight, particularly preferably solid weight. It is 25 to 65 weight%, Most preferably, it is 30 to 50 weight%. As a solvent used, arbitrary appropriate solvents can be employ | adopted according to the kind of curable resin. Specific examples thereof include ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene and the like. These can be used individually or can be used in combination of 2 or more type.

The application amount of the said adhesive agent can be set suitably according to the objective. For example, the coating amount is preferably 0.3 to 3 ml, more preferably 0.5 to 2 ml, most preferably 1 to 2 ml per area (cm 2) of the first or second birefringent layer. After application, the solvent contained in the adhesive is volatilized by natural drying or heat drying as necessary. The thickness of the adhesive layer thus obtained is preferably 0.1 µm to 20 µm, more preferably 0.5 µm to 15 µm, and most preferably 1 µm to 10 µm. In addition, the microhardness of the adhesive layer is preferably 0.1 to 0.5 GPa, more preferably 0.2 to 0.5 GPa, and most preferably 0.3 to 0.4 GPa. Moreover, indentation hardness can also be converted into Vickers hardness, since the correlation with Vickers hardness is known. Indentation hardness can be computed from indentation depth and indentation load, for example using Nippon Denki Corporation (NEC) thin film hardness meter (for example, brand name: MH4000, brand name MHA-400).

Finally, when the substrate is peeled off from the second birefringent layer, the lamination of the first birefringent layer and the second birefringent layer is completed. In this way, the elliptical polarizing plate of the present invention is obtained.

B-6. Concrete manufacturing order

An example of the specific procedure of the manufacturing method of this invention is demonstrated with reference to FIGS. 3-7, the code | symbol 111, 111 ', 112, 112', 115, and 116 are rolls which wind the film and / or laminated body which form each layer.

First, the long polymer film used as a raw material of a polarizer is prepared, and said A-4. Dyeing, stretching, etc. are performed as described in the section. Stretching is performed continuously in the longitudinal direction with respect to a long polymer film. Thereby, as shown in the perspective view of FIG. 3, the elongate polarizer 11 which has an absorption axis in the longitudinal direction (extension direction: arrow A direction) is obtained.

On the other hand, as shown to the perspective view of FIG.4 (a), the elongate transparent protective film 12 (finally becomes a 1st protective layer) is prepared, and the rubbing process by the rubbing roll 120 is carried out to the one surface. Is carried out. At this time, a rubbing direction makes it a direction different from the longitudinal direction of the transparent protective film 12, for example, the direction of +/- 17.5 degrees. Next, as shown to the perspective view of FIG.4 (b), on the transparent protective film 12 which performed the said rubbing process, said B-2. And B-3. The first birefringent layer 13 is formed as described in the section. Since the liquid crystal material is oriented along the rubbing direction of the first birefringent layer 13, the slow axis direction is substantially the same direction (arrow B direction) as the rubbing direction of the transparent protective film 12.

Subsequently, as shown in the schematic diagram of FIG. 5, the transparent protective film (15: becomes a second protective layer), the polarizer 11, the transparent protective film (12: becomes a protective layer), and the first birefringent layer 13 ), The laminate 121 is sent in the direction of the arrow, and attached with an adhesive or the like (not shown) in a state where the respective longitudinal directions are equally aligned. In addition, in FIG. 5, the code | symbol 122 shows the guide roll for sticking films (the same also in FIG. 6 and FIG. 7).

As shown in the schematic diagram of FIG. 6 (a), a long laminate 125 (where the second birefringent layer 14 is supported on the substrate 26) is prepared, and this and the laminate 123 are made. 2 protective layer (15: transparent protective film), polarizer 11, protective layer (12: transparent protective film), and 1st birefringence layer 13 are sent to arrow direction, and the state of each length direction being matched the same. It adheres by adhesive etc. (not shown). Thus, according to this invention, it becomes possible to adhere | attach the very thin 1st and 2nd birefringence layer by what is called a roll to roll, and manufacturing efficiency can be improved significantly.

Finally, as shown in FIG.6 (b), when the base material 26 is peeled off, the elliptical polarizing plate 10 of this invention is obtained.

Another example of the specific procedure of the production method of the present invention will be described.

As shown above, as shown in the perspective view of FIG. 3, the elongate polarizer 11 is manufactured.

On the other hand, as shown to the perspective view of FIG.4 (a), the elongate transparent protective film 12 (finally becomes a 1st protective layer) is prepared, and the rubbing process by the rubbing roll 120 is performed to the one surface. Conduct. At this time, the rubbing direction is a direction different from the longitudinal direction of the transparent protective film 12, for example, a direction of ± 17.5 °.

Next, as shown in the schematic diagram of FIG. 7, the 2nd transparent protective film (15: becomes a 2nd protective layer), the polarizer 11, and a transparent protective film (12: becomes a protective layer) are sent to an arrow direction, respectively. It adheres by adhesive etc. (not shown) in the state to which the longitudinal direction of the same was matched. At this time, the transparent protective film 12 to which the rubbing process was performed is sent facing the polarizer 11 with the opposite side of the surface on which the rubbing process was performed. As a result, a laminated body 126 of the second protective layer 15 (transparent protective film) / polarizer 11 / protective layer 12: transparent protective film is obtained.

Subsequently, on the surface which performed the said rubbing process of the protective layer (12: transparent protective film), said B-2. And B-3. As described in the above section, the first birefringent layer 13 is formed (not shown). Since the liquid crystal material is oriented along the rubbing direction, the first birefringent layer 13 is substantially in the same direction as the rubbing direction of the protective layer 12 (transparent protective film). As a result, a laminated body 123 of the second protective layer 15 (transparent protective film) / polarizer 11 / protective layer 12: transparent protective film / first birefringent layer 13 is obtained.

6 (a), the elongate laminated body 125: the base material 26 supported by the 2nd birefringent layer 14 was prepared, and this and the laminated body 123 ( The 2nd protective layer 15 (transparent protective film), the polarizer 11, the protective layer 12 (transparent protective film), and the 1st birefringent layer 13 are sent to the arrow direction, and each longitudinal direction was matched the same. By adhesive or the like (not shown).

Finally, as shown in FIG.6 (b), when the base material 26 is peeled off, the elliptical polarizing plate 10 of this invention is obtained.

Another example of the specific procedure of the manufacturing method of this invention is demonstrated.

As shown above, as shown in the perspective view of FIG. 3, the elongate polarizer 11 is manufactured.

Next, as shown in the schematic diagram of FIG. 7, the 2nd transparent protective film (15: becomes a 2nd protective layer), the polarizer 11, and a transparent protective film (12: becomes a protective layer) are sent to an arrow direction, respectively. It adheres by adhesive etc. (not shown) in the state to which the longitudinal direction of the same was matched. As a result, a laminated body 126 of the second protective layer 15 (transparent protective film) / polarizer 11 / protective layer 12: transparent protective film is obtained.

Next, a rubbing process is performed with the rubbing roll on the surface of one side (opposite to the polarizer 11) of the transparent protective film 12 similarly to the above (not shown). At this time, a rubbing direction makes it a direction different from the longitudinal direction of the transparent protective film 12, for example, +23 degrees-+24 degrees, or -23 degrees--24 degrees.

Subsequently, on the surface which performed the said rubbing process of the protective layer (12: transparent protective film), said B-2. And B-3. As described in the above section, the first birefringent layer 13 is formed (not shown). Since the liquid crystal material is oriented along the rubbing direction of the first birefringent layer 13, the slow axis direction is substantially the same as the rubbing direction of the protective layer 12 (transparent protective film). As a result, a laminated body 123 of the second protective layer 15 (transparent protective film) / polarizer 11 / protective layer 12: transparent protective film / first birefringent layer 13 is obtained.

As shown in the schematic diagram of Fig. 6 (a), a long laminate 125 (where the second birefringent layer 14 is supported on the base material 26) is prepared, and this and the laminate (123) are made. 2 protective layer (15: transparent protective film), polarizer 11, protective layer (12: transparent protective film), and 1st birefringence layer 13 are sent to arrow direction, and the state of each length direction being matched the same. It adheres by adhesive etc. (not shown). As described above, the slow axis direction (angle α) of the first birefringent layer 13 is + 23 ° to + 24 ° or -23 ° to -24 ° with respect to the longitudinal direction of the film (absorption axis of the polarizer 11). If set, the slow axis of the second birefringent layer 14 may be substantially orthogonal to the longitudinal direction of the film (absorption axis of the polarizer 11).

Finally, as shown in FIG.6 (b), when the base material 26 is peeled off, the elliptical polarizing plate 10 of this invention is obtained.

B-7. Other components of elliptical polarizer

The elliptical polarizing plate of the present invention may further include another optical layer. As such another optical layer, arbitrary appropriate optical layers can be employ | adopted according to the objective or the kind of image display apparatus. As a specific example, another birefringence layer (retardation film), a liquid crystal film, a light scattering film, a diffraction film, etc. are mentioned.

The elliptical polarizing plate of the present invention may further have an adhesive layer as at least one of the outermost layers. Thus, by having an adhesion layer as outermost layer, lamination | stacking with another member (for example, a liquid crystal cell) becomes easy, for example, and peeling from the other member of an elliptically polarizing plate can be prevented. Arbitrary suitable materials can be employ | adopted as a material of the said adhesive layer. As a specific example of an adhesive agent, said B-4. The thing of the term is mentioned. Preferably, a material having excellent hygroscopicity and heat resistance is used. It is because the fall of the optical characteristic by foaming and peeling by moisture absorption, the difference in thermal expansion, etc., the curvature of a liquid crystal cell, etc. can be prevented.

In practice, the surface of the pressure-sensitive adhesive layer may be covered by any suitable separator until the elliptical polarizing plate is actually used, thereby preventing contamination. The separator can be formed by, for example, a method of forming a release coat with a release agent such as silicone-based, long-chain alkyl-based, fluorine-based, molybdenum sulfide, or the like, as necessary for any suitable film.

Each layer in the elliptic polarizing plate of the present invention is, for example, treated with an ultraviolet absorber such as a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, a nickel complex salt compound, or the like. The ultraviolet absorbing ability may be provided by this.

C. Use of Elliptical Polarizer

The elliptical polarizing plate of the present invention can be suitably used for various image display devices (for example, liquid crystal display devices and self-luminous display devices). Specific examples of the applicable image display device include a liquid crystal display device, an EL display, a plasma display (PD), and a field emission display (FED). When using the elliptically polarizing plate of this invention for a liquid crystal display device, it is useful for viewing angle compensation, for example. The elliptical polarizing plate of the present invention is used in, for example, a liquid crystal display device in a circular polarization mode, and is particularly useful for homogeneous alignment type TN liquid crystal display devices, horizontal electrode (IPS) liquid crystal display devices, vertical alignment (VA) type liquid crystal display devices, and the like. Do. In addition, when using the elliptical polarizing plate of this invention for an EL display, it is useful for the electrode reflection prevention, for example.

D. Image Display

As an example of the image display device of the present invention, a liquid crystal display device will be described. Here, the liquid crystal panel used for a liquid crystal display device is demonstrated. As for the other configurations of the liquid crystal display device, any appropriate configuration can be adopted according to the purpose. 8 is a schematic cross-sectional view of a liquid crystal panel according to a preferred embodiment of the present invention. The liquid crystal panel 100 includes a liquid crystal cell 20, retardation plates 30 and 30 ′ disposed on both sides of the liquid crystal cell 20, and polarizing plates 10 and 10 ′ arranged outside of each retardation plate. It is provided. As the retardation plates 30 and 30 ', any appropriate retardation plates can be adopted depending on the purpose and the alignment mode of the liquid crystal cell. Depending on the purpose and the alignment mode of the liquid crystal cell, one or both of the retardation plates 30 and 30 'may be omitted. The polarizing plate 10 is an elliptical polarizing plate of the present invention described in the above sections A. and B.. This polarizing plate 10 (elliptical polarizing plate) is disposed such that the birefringent layers 13 and 14 are positioned between the polarizer 11 and the liquid crystal cell 20. The polarizing plate 10 'is any appropriate polarizing plate (preferably, it is an elliptical polarizing plate of the present invention described in the above sections A. and B.). The polarizing plates 10 and 10 'are typically arranged so that their absorption axes are orthogonal to each other. As shown in FIG. 8, in the liquid crystal display device (liquid crystal panel) of this invention, it is preferable that the elliptically polarizing plate 10 of this invention is arrange | positioned at the visual recognition side (upper side). The liquid crystal cell 20 has a pair of glass substrates 21 and 21 'and the liquid crystal layer 22 as a display medium arrange | positioned between the board | substrates. On one substrate 21 '(active matrix substrate), a switching element (typically TFT) for controlling the electro-optical characteristics of the liquid crystal, a scanning line for supplying a gate signal to the active element, and a signal line for supplying a source signal are provided. (Not shown). A color filter (not shown) is formed on the other glass substrate 21 (color filter substrate). In addition, you may form a color filter in the active-matrix board | substrate 21 '. The gap (cell gap) of the substrates 21 and 21 'is controlled by a spacer (not shown). The alignment film (not shown) which consists of polyimide, for example is formed in the side which contact | connects the liquid crystal layer 22 of the board | substrates 21 and 21 '.

For example, the display mechanism of the VA mode will be described. 9 is a schematic cross-sectional view illustrating the alignment state of liquid crystal molecules in VA mode. As shown in Fig. 9 (a), when no voltage is applied, the liquid crystal molecules are oriented perpendicular to the surface of the substrates 21 and 21 '. Such vertical alignment can be realized by disposing a nematic liquid crystal having negative dielectric anisotropy between the substrates on which the vertical alignment film (not shown) is formed. In this state, when the light of the linearly polarized light passing through the polarizing plate 10 'is incident on the liquid crystal layer 22 on one substrate 21' surface, the incident light travels along the long axis direction of the liquid crystal molecules that are vertically aligned. do. Since birefringence does not occur in the long axis direction of the liquid crystal molecules, incident light proceeds without changing the polarization direction and is absorbed by the polarizing plate 10 having a polarizing axis orthogonal to the polarizing plate 10 '. As a result, dark display is obtained when no voltage is applied (normally black mode). As shown in Fig. 9B, when a voltage is applied between the electrodes, the long axis of the liquid crystal molecules is aligned parallel to the substrate surface. The liquid crystal molecules exhibit birefringence with respect to the linearly polarized light incident on the liquid crystal layer 22 in this state, and the polarization state of the incident light changes according to the inclination of the liquid crystal molecules. The light passing through the liquid crystal layer 22 at the time of applying a predetermined maximum voltage becomes linearly polarized light whose polarization direction is rotated by 90 °, for example, so that a bright state display is obtained by passing through the polarizing plate 10. Lose. When the voltage is not applied again, the display of the dark state can be returned by the orientation regulating force. In addition, gray scale display is enabled by changing the applied voltage to control the inclination of the liquid crystal molecules to change the transmitted light intensity from the polarizing plate 10.

Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited by these Examples. The measuring method of each characteristic in an Example is as follows.

(1) Measurement of phase difference

The refractive indices nx, ny and nz of the sample film were measured by the automatic birefringence measuring apparatus (Oji Measurement Instruments Co., Ltd., automatic birefringence meter KOBRA31PR), and the in-plane phase difference (Δnd) and the thickness direction phase difference (Rth) were calculated. The measurement temperature was 23 ° C and the measurement wavelength was 590 nm.

(2) measurement of thickness

The thickness of the 1st and 2nd birefringence layer was measured by the interference film thickness measuring method using MCPD2000 by Otsuka Electronics. The thickness of other various films was measured using the dial gauge.

(3) Measurement of transmittance

The same elliptical polarizing plates obtained in Example 1 were attached. The transmittance | permeability of the attached sample was measured by brand name DOT-3 (made by Murakami Corporation).

(4) Measurement of contrast ratio

The same elliptical polarizers overlap each other, and the white image (the absorption axis of the polarizer is parallel) and the black image (the absorption axis of the polarizer are vertical) are displayed, and the viewing side polarizer is made by ELDIM brand name "EZ Contrast 160D". Scanned in the direction of 45 ° to 135 ° with respect to the absorption axis of and from -60 ° to 60 ° with respect to the normal line. And the contrast ratio "YW / YB" of the diagonal direction was computed from the Y value (YW) of a white image, and the Y value (YB) of a black image.

Example 1

I. Orientation Treatment of Transparent Protective Film (Preparation of Orientation Substrate)

The transparent protective film (T) was subjected to an orientation treatment to prepare an orientation substrate (finally the protective layer 12).

Substrate (1)-(8): After forming a PVA film (0.1 micrometer in thickness) on the surface of a TAC film (40 micrometers in thickness), using a rubbing cloth, rubbing the said PVA film surface at the rubbing angle shown in the following table, An orientation substrate was produced.

Substrate (9)-(10): The TAC film (40 micrometers in thickness) was rubbed at the rubbing angle shown in the following table using the rubbing cloth, and the orientation base material was produced.

II. Fabrication of the first birefringent layer

First, 10 g of polymerizable liquid crystals (liquid crystal monomers) (manufactured by BASF Corporation: trade name Paliocolor LC242) showing a nematic liquid crystal phase, and a photopolymerization initiator (manufactured by Chiba Specialty Chemicals Corporation: trade name Irgacure 907) for the polymerizable liquid crystal compound. Was dissolved in 40 g of toluene to prepare a liquid crystal coating liquid. And after apply | coating this liquid crystal coating liquid with the bar coater on the orientation base material produced as mentioned above, the liquid crystal was orientated by heat-drying at 90 degreeC for 2 minutes. The 1st birefringence layers (1)-(3) were formed by irradiating 1mJ / cm <2> light to this liquid crystal layer using the metal halide lamp, polymerizing the polymerizable liquid crystal of the said liquid crystal, and fixing the orientation of a liquid crystal layer. The thickness and retardation of the first birefringent layer were adjusted by changing the coating amount of the liquid crystal coating liquid. The thickness and in-plane retardation value (nm) of the formed 1st birefringent layer are shown in the following table | surface.

III. Fabrication of the second birefringent layer

III-a. Preparation of Equipment

The polyethylene terephthalate roll (width 4m) which has an orientation axis in the width direction, and the deviation of an orientation axis is within +/- 1 degree with respect to the average direction of an orientation axis | shaft was prepared.

III-b. Formation of Second Birefringence Layer (First)

First, 9.9964 g of a polymerizable liquid crystal (liquid crystal monomer) exhibiting a nematic liquid crystal phase (manufactured by BASF Corporation: trade name Paliocolor LC242; represented by the formula (10)), and a chiral agent (manufactured by BASF Corporation: trade name Paliocolor LC756; the above formula (36)) 3g of 0.0036 g and a photoinitiator (Ciba Specialty Chemicals make: brand name Irgacure 907) with respect to the said polymeric liquid crystal compound were melt | dissolved in 40 g of toluene, and the liquid crystal coating liquid was prepared. The following procedure was performed similarly to said II, and the 2nd birefringent layer 21 was formed. In the following table, the thickness of the formed second birefringent layer, the in-plane retardation value (nm), and the direction of the slow axis with respect to the absorption axis of the polarizer are shown.

III-b. Formation of Second Birefringence Layer (Second)

First, 9.9930 g of a polymerizable liquid crystal (liquid crystal monomer) (manufactured by BASF Corporation: trade name Paliocolor LC242) exhibiting a nematic liquid crystal phase, 0.0070 g of a chiral agent (manufactured by BASF Corporation: trade name Paliocolor LC756), and the polymerizable liquid crystal compound 3 g of a photoinitiator (Ciba Specialty Chemicals make: brand name Irgacure 907) was melt | dissolved in 40 g of toluene, and the liquid crystal coating liquid was prepared. The following procedure was performed similarly to said II, and the 2nd birefringent layer 22 was formed. In the following table, the thickness of the formed second birefringent layer, the in-plane retardation value (nm), and the direction of the slow axis with respect to the absorption axis of the polarizer are shown.

III-b. Formation of Second Birefringence Layer (Third)

First, 9.9899 g of a polymerizable liquid crystal (liquid crystal monomer) (manufactured by BASF Corporation: trade name Paliocolor LC242) exhibiting a nematic liquid crystal phase, 0.0101 g of a chiral agent (manufactured by BASF Corporation: trade name Paliocolor LC756), and the polymerizable liquid crystal compound 3 g of a photoinitiator (Ciba Specialty Chemicals make: brand name Irgacure 907) was melt | dissolved in 40 g of toluene, and the liquid crystal coating liquid was prepared. The following procedure was performed similarly to said II, and the 2nd birefringent layer 23 was formed. In the following table, the thickness of the formed second birefringent layer, the in-plane retardation value (nm), and the direction of the slow axis with respect to the absorption axis of the polarizer are shown.

Ⅳ. Fabrication of Elliptical Polarizers

After dyeing a polyvinyl alcohol film in the aqueous solution containing iodine, it uniaxially stretched 6 times between rolls from which the speed ratio differs in the aqueous solution containing boric acid, and obtained the polarizer. In the combination shown in the following table, a protective layer, a first birefringent layer and a second birefringent layer were used. These polarizers, a protective layer, a 1st birefringent layer, and a 2nd birefringent layer were laminated | stacked according to the manufacturing procedure shown in FIGS. 3-7, and elliptical polarizing plates A01-A18 as shown in FIG. 1 were obtained.

Example 2

The elliptical polarizing plate A09 was superimposed and the contrast ratio was measured. According to this elliptical polarizing plate, the angle of contrast 10 was 10 degrees in the minimum 40 degree, the maximum 50 degree, and the maximum minimum difference in the whole orientation. It was a practically desirable level that the angle of contrast 10 was at least 40 degrees in the overall orientation. Moreover, since the maximum minimum difference was small by 10 degrees, the balance was good in visual characteristics, and this was also a very preferable level in practical use.

Example 3

The elliptical polarizing plate A01 was superimposed and the contrast ratio was measured. According to this elliptical polarizing plate, the angle of contrast 10 was 20 degree in the minimum 40 degree, the maximum 60 degree, and the maximum minimum difference in the whole orientation. It was a practically desirable level that the angle of contrast 10 was at least 40 degrees in the overall orientation.

The elliptical polarizing plate of the present invention can be suitably used for various image display devices (for example, liquid crystal display devices and self-luminous display devices).

Claims (16)

Polarizer; A protective layer formed on one side of the polarizer; a first birefringent layer functioning as a λ / 2 plate; And a second birefringent layer functioning as a λ / 4 plate in this order, When the angle formed by the absorption axis of the polarizer and the slow axis of the first birefringent layer is α, and the angle formed by the absorption axis of the polarizer and the slow axis of the second birefringent layer is β, the angle α is 10 °. -20 degrees or -10 degrees --20 degrees, the angle (beta) is 65 degrees-85 degrees, or 5 degrees-25 degrees, The refractive index distribution of the first birefringent layer is nx> ny = nz, and the refractive index distribution of the second birefringent layer is nx> ny> nz, The first birefringent layer is formed using a liquid crystal material, and the second birefringent layer is formed using a liquid crystal composition containing a liquid crystal material and a chiral agent, and the chiral agent is 0.03 to 0.11 based on 100 parts by weight of the liquid crystal material. Elliptical polarizing plate by weight. delete The method of claim 1, The liquid crystal material forming the second birefringent layer is at least one of the compounds represented by the following formulas (4) to (19), and the chiral agent is at least one of the compounds represented by the following formulas (24) to (44): an ellipse Polarizer: [Formula 1]

[Formula 2]

[Formula 3]

The method of claim 3, wherein The liquid crystal material forming the second birefringent layer is a compound represented by the formula (10), and the chiral agent is a compound represented by the formula (32). The method of claim 1, An elliptical polarizing plate, wherein the thickness of the first birefringent layer is 0.5 to 5 µm. The method of claim 1, An elliptical polarizing plate, wherein the thickness of the second birefringent layer is 0.3 to 3 µm. Process of performing orientation treatment on the surface of transparent protective film (T); Forming a first birefringent layer on the surface subjected to the alignment treatment of the transparent protective film (T); And Laminating the polarizer on the surface of the transparent protective film (T), The polarizer and the first birefringent layer are disposed on opposite sides with the transparent protective film T therebetween, Laminating a second birefringent layer on the surface of the first birefringent layer; The refractive index distribution of the first birefringent layer is nx> ny = nz, and the refractive index distribution of the second birefringent layer is nx> ny> nz, The step of forming the first birefringent layer is performed using a liquid crystal material, and the step of laminating the second birefringent layer is performed using a liquid crystal composition containing a liquid crystal material and a chiral agent, and 100 parts by weight of the liquid crystal material. The chiral agent is 0.03 to 0.11 part by weight based on the method for producing an elliptical polarizing plate. The method of claim 7, wherein The transparent protective film (T), the first birefringent layer, the polarizer, and the second birefringent layer are long films, and the long sides are attached to each other and laminated. The method according to claim 7 or 8, The process of forming a said 1st birefringence layer includes the process of apply | coating the coating liquid containing the said liquid crystal material, and the process of processing and orientating the apply | coated liquid crystal material at the temperature which a said liquid crystal material shows a liquid crystal phase, Method for producing an elliptical polarizing plate. The method of claim 9, The said liquid crystal material contains a polymerizable monomer and / or a crosslinkable monomer, and the orientation process of the said liquid crystal material further includes performing a polymerization process and / or a crosslinking process. The method of claim 10, The polymerization method and / or crosslinking process are performed by heating or light irradiation, The manufacturing method of the elliptical polarizing plate. The method according to claim 7 or 8, The process of laminating | stacking a said 2nd birefringence layer is a process of apply | coating the coating liquid containing the said liquid crystal material and the said chiral agent to a base material; Treating the coating liquid at a temperature at which the liquid crystal material exhibits a liquid crystal phase to form a second birefringent layer on the substrate; And transferring the second birefringent layer formed on the substrate to the surface of the first birefringent layer. delete The method of claim 12, The said base material is a manufacturing method of the elliptic polarizing plate which is a polyethylene terephthalate film obtained by extending | stretching process and recrystallization process. The method of claim 12, The said base material is a manufacturing method of the elliptical polarizing plate used for the application | coating process of the said coating liquid, without performing the orientation process with respect to the said substrate surface. An image display device comprising the elliptical polarizing plate according to claim 1.

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