WO2020130462A1 - Polarizing plate and optical display device including same - Google Patents

Abstract

Provided are: a polarizing plate comprising a polarizing film, and a reverse-wavelength dispersible positive A phase difference layer and a positive C phase difference layer which are formed on the lower surface of the polarizing film, wherein the reverse-wavelength dispersible positive A phase difference layer is directly formed on the positive C phase difference layer, and a laminate having the reverse-wavelength dispersible positive A phase difference layer and the positive C phase difference layer satisfies formula 1 and formula 2; and an optical display device including same.

Description

Polarizing plate and optical display device including same

The present invention relates to a polarizing plate and an optical display device including the same. More specifically, the present invention is excellent in durability and reliability of the amount of retardation change, the adhesive strength between the reverse wavelength dispersibility positive A retardation layer and positive C retardation layer, excellent in thinning and bending reliability, a polarizing plate and an optical display device including the same It is about.

It is necessary for the OLED display device to include a polarizing plate in order to produce an anti-reflective effect by external light. The anti-reflection effect may improve the screen quality of the OLED display device. The polarizing plate includes a two-sheet laminate in which a reverse wavelength dispersion 1/4 phase difference layer and a positive C phase difference layer are stacked on the lower surface of the polarizer, or a two-sheet laminate in which a 1/2 phase difference layer and a 1/4 phase difference layer are stacked. It can contain. In the case of a two-layer laminate in which a reverse wavelength dispersibility 1/4 retardation layer and a positive C retardation layer are stacked, a liquid crystal type positive C retardation layer is used as a positive C retardation layer.

The reverse wavelength dispersibility quarter retardation layer may be a stretched film or a liquid crystal film. However, it was confirmed that the retardation can be changed when the stretched film is left at high temperature or high temperature and high humidity for a long period of time due to shrinkage or axial distortion due to stretching. Since the liquid crystal film also exhibits a phase difference depending on the alignment of the liquid crystal, when left at high temperature or high temperature and high humidity for a long period of time, the liquid crystal alignment may be distorted and the phase difference may change. The phase difference change can also adversely affect the screen quality when applied to an optical display device by causing a phase difference change in a two-layer stacked structure of a reverse wavelength dispersion 1/4 phase difference layer and a positive C phase difference layer.

On the other hand, as interest in a flexible optical display device has recently been amplified, flexibility for a polarizing plate included in the flexible optical display device is also required. A polarizing plate having poor flexibility may cause cracks or cracks when applied to a flexible optical display device, which may adversely affect the screen quality.

Background art of the present invention is disclosed in Korean Patent Publication No. 10-2015-0122410 and the like.

An object of the present invention is to provide a polarizing plate excellent in durability and reliability because the amount of phase difference change is low when left at high temperature and high temperature and high humidity for a long time.

Another object of the present invention is to provide a polarizing plate having excellent adhesion and thinning effect between the reverse wavelength dispersive positive A(+A) retardation layer and the positive C(+C) retardation layer.

Another object of the present invention is to provide a polarizing plate having excellent bending reliability by suppressing the occurrence of mura caused by heat on the side and preventing cracks or cracks due to bending.

One aspect of the present invention is a polarizing plate.

In one embodiment, the polarizing plate includes a polarizing film and a reverse wavelength dispersive positive A retardation layer and a positive C retardation layer formed on the lower surface of the polarizing film, and the reverse wavelength dispersing positive A retardation layer is the positive C retardation layer It is formed directly on, the laminate of the reverse wavelength dispersion positive A retardation layer and the positive C retardation layer satisfies the following Equation 1 and Equation 2:

[Equation 1]

0nm ≤ |Rth[0]-Rth[500]| ≤ 5nm

(Equation 1 above,

Rth[0] is the initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the laminate,

Rth [500] is the phase difference (unit: nm) in the thickness direction at a wavelength of 550 nm of the laminate when the laminate is left at 85° C. for 500 hours,

[Equation 2]

0nm ≤ |Rth[0]-Rth[500]| ≤ 2nm

(In Equation 2 above,

Rth[0] is the initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the laminate,

Rth[500] is the phase difference (unit: nm) in the thickness direction at a wavelength of 550 nm of the laminate when the laminate is left at 60°C and 95% relative humidity for 500 hours.

2. In the above 1 embodiment, the reverse wavelength dispersibility positive A retardation layer may have a thickness direction retardation change amount (ΔRth) according to Equation 3 below 5 nm.

[Equation 3]

Amount of retardation change in thickness direction (△Rth) = |Rth[0]-Rth[500]|

(Equation 3 above,

Rth[0] is an initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the reverse wavelength dispersive positive A retardation layer,

Rth[500] is the thickness direction retardation (unit: nm) at a wavelength of 550 nm of the reverse wavelength dispersive positive A retardation layer when the reverse wavelength dispersive positive A retardation layer is left at 85° C. for 500 hours.

3. In the above 1-2 embodiments, the reverse wavelength dispersibility positive A retardation layer may have a thickness direction retardation change amount (ΔRth) according to Equation 4 below 2 nm.

[Equation 4]

Amount of retardation change in thickness direction (△Rth) = |Rth[0]-Rth[500]|

(In the above equation 4,

Rth[0] is an initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the reverse wavelength dispersive positive A retardation layer,

Rth[500] is a thickness direction phase difference at a wavelength of 550 nm of the reverse wavelength dispersive positive A phase difference layer when the reverse wavelength dispersive positive A phase difference layer is left at 60°C and 95% relative humidity for 500 hours (unit: nm). .

4. In the above 1-3 embodiments, the reverse wavelength dispersibility positive A retardation layer may have an in-plane retardation change (ΔRe) according to Equation 5 below 5 nm or more:

[Equation 5]

In-plane phase difference change amount (△Re) = |Re[0]-Re[1]|

(Equation 5 above,

Re[0] is the wavelength of the MD x TD x (3cm x 3cm x 50㎛) inverse wavelength dispersibility positive A phase difference layer Re (at:550nm wavelength 550nm)

Re[1] is added dropwise with 1 drop of methyl ethyl ketone to the specimen of the reverse wavelength dispersible positive A retardation layer at 25° C., and after standing for 1 hour, Re(1) at wavelength 550nm of the specimen of the reverse wavelength dispersible positive A retardation layer. Unit:nm))).

5. In the above 1-4 embodiment, the reverse wavelength dispersive positive A phase difference layer is a non-modified polycarbonate-based resin, cyclic olefin polymer resin, modified polycarbonate-based resin, isosorbide-based resin, cellulose-based resin, flu It may include a polymer film formed of at least one of an orene-based resin, a polyester-based resin.

6. In the above 1-5 embodiment, the reverse wavelength dispersibility positive A phase difference layer may include a liquid crystal layer formed of at least one liquid crystal among nematic liquid crystal, smectic liquid crystal, and cholesteric liquid crystal.

7. In the above 1-6 embodiment, the reverse wavelength dispersive positive A retardation layer may have an nx of 0.001 to 0.002, ny of -0.002 to -0.001, and nz of -0.002 to -0.001 at a wavelength of 550 nm.

8. In the above 1-7 embodiment, the positive C retardation layer is a non-liquid crystal layer and may not have an alignment layer.

9. In the above 1-8 embodiment, the positive C retardation layer may include a coating layer formed of a composition comprising at least one of a cellulose ester or a polymer thereof and an aromatic polymer.

10. In the above 9 embodiment, the cellulose ester may include at least one of cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate.

11. In the embodiment 1-10, the positive C phase difference layer may have an nx of -0.002 to -0.001, ny of -0.002 to -0.001, and nz of 0.001 to 0.002 at a wavelength of 550 nm.

12. In the embodiment 1-11, the stack of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer may have an Rth of -50 nm to 50 nm at a wavelength of 550 nm.

13. In the embodiment 1-12, the reverse wavelength dispersive positive A phase difference layer and the positive C phase difference layer may be sequentially formed on the lower surface of the polarizing film.

14. In the embodiment 1-13, the reverse wavelength dispersion positive A retardation layer may further include a buffer layer on one surface in contact with the positive C retardation layer.

15. In the above 14 embodiment, the buffer layer may have an in-plane retardation Re of 5 nm or less at a wavelength of 550 nm.

16. In the 14 embodiment, the buffer layer may occupy 1% to 20% of the total thickness of the inverse wavelength dispersion positive A retardation layer.

The optical display device of the present invention includes the polarizing plate of the present invention.

The present invention provides a polarizer having excellent durability and reliability due to a low amount of phase difference when left for a long time at high temperature and high temperature and high humidity.

The present invention provides a polarizing plate having excellent adhesion between the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer and thinning.

The present invention provides a polarizing plate having excellent bending reliability by suppressing the occurrence of mura due to heat on the side and preventing cracks or cracks due to bending.

FIG. 1 shows Rth at a wavelength of 550 nm according to the standing time when the reverse wavelength dispersive positive A phase difference layer of Example 1 was left at 85°C.

Figure 2 shows the Rth at a wavelength of 550nm of the reverse wavelength dispersion positive A phase difference layer according to the standing time when the reverse wavelength dispersion positive A retardation layer of Example 1 was left at 60 ℃ and 95% relative humidity.

FIG. 3 shows the Rth at a wavelength of 550 nm of the stack according to the standing time when the stack of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer of Example 1 was left at 85°C.

Figure 4 shows the Rth at a wavelength of 550nm of the laminate according to the standing time when the stack of the reverse wavelength dispersibility positive A phase difference layer and the positive C phase difference layer of Example 1 was left at 60 °C and 95% relative humidity will be.

With reference to the accompanying drawings, it will be described in detail so that those skilled in the art to which the present invention pertains can be easily implemented by the following examples. The present invention can be implemented in many different forms and is not limited to the embodiments described herein.

In this specification, "in-plane retardation (Re)" is represented by Equation A below, "thickness phase retardation (Rth)" is represented by Equation B below, and "degree of biaxiality (NZ)" can be represented by Equation C below. have:

[Equation A]

Re = (nx-ny) x d

[Equation B]

Rth = ((nx + ny)/2-nz) x d

[Equation C]

NZ = (nx-nz)/(nx-ny)

(In the above formulas A to C, nx, ny, and nz are the refractive indexes of the slow axis direction, the fast axis direction, and the thickness direction of the optical element, respectively, at the measurement wavelength, and d is the thickness of the optical element (unit: nm)).

The “measurement wavelength” may mean a wavelength of 450 nm, 550 nm or 650 nm. The "optical device" may mean a reverse wavelength dispersive A retardation layer, a positive C retardation layer, or a stack of a reverse wavelength dispersive positive A retardation layer and a positive C retardation layer.

When describing a numerical range in this specification, "X to Y" means X or more and Y or less (X≤ and ≤Y).

The inventor of the present invention has a reversed-wavelength dispersibility positive A phase difference layer having low durability and low reliability when the thickness direction retardation (Rth) change amount is high for high temperature and high temperature and high humidity, respectively, in the reverse wavelength dispersion positive By forming a specific positive C retardation layer directly on the A retardation layer, even when the reverse wavelength dispersion positive A retardation layer is left for a long time at high temperature and high temperature and high humidity, the thickness direction retardation (Rth) change amount is low, and the bending reliability is excellent, From the side, it was confirmed that there is an effect of suppressing the occurrence of mura caused by heat, and the present invention was completed.

The positive C retardation layer is formed by directly coating the composition for the positive C retardation layer on the reverse wavelength dispersive positive A retardation layer. The amount of change in the thickness direction retardation (Rth) of the reverse wavelength dispersive positive A retardation layer is low. When the laminate of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer is left at high temperature and high temperature for a long period of time, the laminate It can be confirmed that the Rth change amount is low.

Hereinafter, a polarizing plate of an embodiment of the present invention will be described.

The polarizing plate includes a polarizing film and an inverse wavelength dispersive positive A retardation layer and a positive C retardation layer laminated on the lower surface of the polarizing film, and the reverse wavelength dispersing positive A retardation layer is formed directly on the positive C retardation layer It is done. The "directly formed" means that any other adhesive layer, adhesive layer, adhesive layer, or the like is not formed between the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer.

A stack of a reverse wavelength dispersive positive A retardation layer and a positive C retardation layer is formed on a lower surface of a polarizing film to improve screen quality in a display device to which a polarizing plate is applied. If the stack of the reverse wavelength dispersibility positive A retardation layer and positive C retardation layer secures a retardation within a predetermined range, it is possible to improve screen quality by preventing reflection of external light. However, in order to secure the reliability of the polarizing plate, the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer, respectively, are left even if the stack of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer is left at high temperature and high temperature and high humidity for a long time. It should be stably expressed without changing the phase difference. In particular, the amount of phase difference in the thickness direction of the stack of the reverse wavelength dispersibility positive A retardation layer and the positive C retardation layer should be low, so that the side screen quality improvement effect can be stably exhibited even when left at high temperature and high temperature and high humidity for a long time.

The present inventor directly forms a specific positive C retardation layer on the reverse wavelength dispersive positive A retardation layer, so that the laminate of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer satisfies Equations 1 and 2 below. It was confirmed that:

[Equation 1]

0nm ≤ |Rth[0]-Rth[500]| ≤ 5nm

(Equation 1 above,

Rth[0] is the initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the laminate,

Rth [500] is the phase difference (unit: nm) in the thickness direction at a wavelength of 550 nm of the laminate when the laminate is left at 85° C. for 500 hours,

[Equation 2]

0nm ≤ |Rth[0]-Rth[500]| ≤ 2nm

(In Equation 2 above,

Rth[0] is the initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the laminate,

Rth[500] is the phase difference (unit: nm) in the thickness direction at a wavelength of 550 nm of the laminate when the laminate is left at 60° C. and 95% relative humidity for 500 hours,

By satisfying the above Equations 1 and 2, even if the polarizing plate is left at high temperature and high temperature and high humidity for a long time, the amount of phase difference change is low, thereby improving durability and reliability of maintaining screen quality. In the expression 1, |Rth[0]-Rth[500]| is 0 nm to 5 nm, the thickness direction phase difference change amount of the reverse wavelength dispersion positive A phase difference layer in which the thickness direction phase difference change amount according to the following equation 3 is more than 5 nm can be lowered. It means there is. When Rth[0]-Rth[500]| of Equation 2 is 0 nm to 2 nm, the amount of retardation in the thickness direction of the reverse wavelength dispersion positive A retardation layer in which the amount of retardation in the thickness direction according to Equation 4 is greater than 2 nm can be lowered. It means there is.

Specifically, |Rth[0]-Rth[500]| in Equation 1 may be 0 nm to 3 nm.

In one embodiment, when the reverse wavelength dispersive positive A retardation layer is a stretched film or a liquid crystal film, a stack of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer is positive C on the reverse wavelength dispersibility positive A retardation layer It can be prepared by directly coating and curing the composition for the retardation layer.

In another embodiment, when the reverse wavelength dispersive positive A retardation layer is a liquid crystal coating layer, the stack of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer comprises a composition for the reverse wavelength dispersibility positive A retardation layer on the positive C retardation layer. It can be prepared by directly coating and curing.

The stack of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer may have Rth[0] of Equation 1 and Equation 2 of -50 nm to 50 nm, preferably -40 nm to 30 nm. In the above range, when applied to a display device, it is possible to improve screen quality by acting on external light.

The stack of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer may have Rth [500] of Equation 1 and Equation 2 of -50 nm to 50 nm, specifically -40 nm to 30 nm. In the above range, when applied to a display device, it is possible to improve screen quality by acting on external light.

The stack of the reverse wavelength dispersion positive A retardation layer and the positive C retardation layer may have an in-plane retardation (Re) of 110 nm to 170 nm, specifically 130 nm to 140 nm at a wavelength of 550 nm. In the above range, when applied to a display device, it is possible to improve screen quality by acting on external light.

The stack of the reverse wavelength dispersive positive A retardation layer and positive C retardation layer may have a thickness of 1 μm to 90 μm, specifically 1 μm to 60 μm, and more specifically 5 μm to 60 μm. In the above range, it may be used in a polarizing plate and may have a thinning effect.

In one embodiment, a reverse wavelength dispersive positive A retardation layer and a positive C retardation layer may be sequentially stacked on the lower surface of the polarizing film. Although the present invention is not limited thereto, the screen quality improvement effect may be better when sequentially stacked in the order of the reverse wavelength dispersion positive A retardation layer and positive C retardation layer from the lower surface of the polarizing film.

Inverse wavelength dispersion positive A phase difference layer

Hereinafter, the reverse wavelength dispersion positive A phase difference layer of the present invention will be described in detail.

The reverse wavelength dispersibility positive A retardation layer may be a reverse wavelength dispersion and a positive A retardation layer having nx>ny≒nz. The'nx, ny, nz' are slow axis, fast axis, and refractive index in the thickness direction at a wavelength of 550 nm of the inverse wavelength dispersion positive A phase difference layer, respectively.

The "reverse wavelength dispersion" is the ratio of the in-plane retardation Re(450) at the wavelength 450nm to the in-plane retardation Re(550) at the wavelength 550nm of the reverse wavelength dispersibility positive A retardation layer (Re(450)/Re(550) )) may be 0.7 to 1.0. Specifically, the reverse wavelength dispersive positive A retardation layer may have Re(450)/Re(550) of 0.7 to 0.9, more preferably 0.8 to 0.9. In the above range, it is possible to increase the antireflection effect together with the positive C phase difference layer.

The "reverse wavelength dispersibility" is the ratio of the in-plane retardation Re(650) at the wavelength 650nm to the in-plane retardation Re(550) at the wavelength 550nm of the reverse wavelength dispersibility positive A retardation layer (Re(650)/Re(550) )) may be 1.0 to 1.4, preferably 1.0 to 1.1. In the above range, it is possible to increase the antireflection effect together with the positive C phase difference layer.

The “reverse wavelength dispersion” may be Re(450)/Re(550) <Re(650)/Re(550).

The reverse wavelength dispersive positive A retardation layer may have an in-plane retardation Re(550) of 110 nm to 170 nm, for example, 130 nm to 155 nm, 130 nm to 150 nm, 130 nm to 140 nm at a wavelength of 550 nm. In the above range, it is possible to increase the antireflection effect together with the positive C phase difference layer.

The reverse wavelength dispersive positive A retardation layer may have a thickness direction retardation Rth of 60 nm to 100 nm, for example, 70 nm to 95 nm at a wavelength of 550 nm. In the above range, it is possible to increase the antireflection effect together with the positive C phase difference layer.

The reverse wavelength dispersive positive A retardation layer may have a degree of biaxiality NZ of 0.6 to 1.4, for example, 0.8 to 1.2 at a wavelength of 550 nm. In the above range, it may be effective to further reduce the reflectance when laminated to a polarizing film.

The reverse wavelength dispersive positive A retardation layer may have an nx of 0.001 to 0.002, ny of -0.002 to -0.001, and nz of -0.002 to -0.001 at a wavelength of 550 nm. In the above range, the reverse wavelength dispersion positive A phase difference implementation of the present invention may be possible.

The reverse wavelength dispersive positive A retardation layer may have a thickness direction retardation variation according to Equation 3 below greater than 5 nm, for example greater than 5 nm and less than 20 nm.

[Equation 3]

Amount of retardation change in thickness direction (△Rth) = |Rth[0]-Rth[500]|

(Equation 3 above,

Rth[0] is an initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the reverse wavelength dispersive positive A retardation layer,

Rth[500] is the thickness direction retardation (unit: nm) at a wavelength of 550 nm of the reverse wavelength dispersive positive A retardation layer when the reverse wavelength dispersive positive A retardation layer is left at 85° C. for 500 hours.

The reverse wavelength dispersive positive A retardation layer may have a thickness direction retardation variation according to Equation 4 below greater than 2 nm, for example greater than 2 nm and less than 20 nm.

[Equation 4]

Amount of retardation change in thickness direction (△Rth) = |Rth[0]-Rth[500]|

(In the above equation 4,

Rth[0] is an initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the reverse wavelength dispersive positive A retardation layer,

Rth[500] is a thickness direction phase difference at a wavelength of 550 nm of the reverse wavelength dispersive positive A phase difference layer when the reverse wavelength dispersive positive A phase difference layer is left at 60°C and 95% relative humidity for 500 hours (unit: nm). .

In one embodiment, the reverse wavelength dispersive positive A retardation layer can be a polymer film or a liquid crystal film.

In one embodiment, the reverse wavelength dispersive positive A retardation layer can be a polymer film. The polymer film is a polycarbonate-based resin (non-modified polycarbonate-based resin), a cyclic olefin polymer resin, a modified polycarbonate-based resin, an isosorbide-based resin, a cellulose-based resin including a triacetyl cellulose-based resin, and a fluorene-based resin. It may be a polymer film formed of at least one of resins and polyester resins. These films had a large amount of retardation in the thickness direction when they were left for a long time at high temperature and high temperature and high humidity.

Preferably, the reverse wavelength dispersive positive A retardation layer is a film formed of a polycarbonate-based resin, a triacetylcellulose-based resin, etc., more preferably a film formed of a composition comprising a modified polycarbonate-based resin or a modified polycarbonate-based resin. Can be

The reverse wavelength dispersive positive A retardation layer may be prepared by uniaxially or biaxially stretching or obliquely stretching the polymer film in an unstretched state. The stretching method may be dry stretching or wet stretching, and detailed methods are known to those skilled in the art.

In one embodiment, when the machine direction (MD) of the reverse wavelength dispersive positive A retardation layer is 0°, the optical axis (slow axis of the reverse wavelength dispersive positive A retardation layer) is -5° to 5° or 40° to An angle of 50°, for example -5 to 5° or 45±3° (42° to 48°) can be achieved. The reverse wavelength dispersive positive A retardation layer having an optical axis of 0° with respect to the MD of the reverse wavelength dispersing positive A retardation layer means a film stretched with MD of the reverse wavelength dispersing positive A retardation layer. For the MD of the reverse wavelength dispersible positive A retardation layer, the reverse wavelength dispersive positive A retardation layer having an optical axis of -5° or more but less than 0°, more than 0° and less than 5°, and 40° to 50° means an obliquely stretched film do. In the angular range, when combined with the positive C layer, an anti-reflection effect can be obtained.

In another embodiment, the reverse wavelength dispersive positive A retardation layer can be a liquid crystal film. When the liquid crystal film is left for a long time at high temperature or high temperature and high humidity, the amount of retardation may be increased as the alignment of the liquid crystal is distorted. The present invention lowers the amount of phase difference change when left at high temperature or high temperature and high humidity for a long time by directly forming a specific positive C retardation layer on such a liquid crystal film.

In the liquid crystal film, an alignment layer may be formed on one surface of the liquid crystal film or there may be no alignment layer.

The liquid crystal film may be a liquid crystal layer formed of a liquid crystal composition including at least one of nematic liquid crystal, smectic liquid crystal, and cholesteric liquid crystal. The liquid crystal may be either a temperature-transfer type liquid crystal in which a liquid crystal phase is expressed according to a change in temperature, or a concentration-transition type liquid crystal in which a liquid crystal phase is expressed according to the concentration of a solute in a solution state. The liquid crystal composition includes a liquid crystal, and the content of the liquid crystal may be included in 40 parts by weight to 100 parts by weight based on 100 parts by weight of the solid content of the liquid crystal composition. The liquid crystal composition further contains a chiral agent, so that a film having a desired refractive index can be obtained. The liquid crystal composition may further include additives such as a leveling agent, a polymerization initiator, an alignment aid, a heat stabilizer, a lubricant, a plasticizer, and an antistatic agent.

The reverse wavelength dispersive positive A retardation layer may have a thickness of 1 μm to 90 μm.

In one embodiment, when the reverse wavelength dispersive positive A retardation layer is a polymer film, the thickness may be 20 μm to 70 μm, more preferably 20 μm to 60 μm. In the above range, it can be used for a polarizing plate, and a thinning effect of the polarizing plate can be obtained.

In another embodiment, when the reverse wavelength dispersive positive A retardation layer is a liquid crystal film, the thickness may be 1 μm to 50 μm, more preferably 1 μm to 10 μm. In the above range, it can be used for a polarizing plate, and a thinning effect of the polarizing plate can be obtained.

An adhesive layer, an adhesive layer, or a point adhesive layer is additionally formed on the other side of the reverse wavelength dispersive positive A retardation layer, that is, a surface that does not directly contact the positive C retardation layer, thereby depositing a reverse wavelength dispersive positive A retardation layer (for example, Polarizing film).

Positive C retardation layer

Hereinafter, the positive C phase difference layer of the present invention will be described in detail.

The positive C retardation layer may be a positive C retardation layer having a refractive index relationship of nx ≒ ny <nz. Through this, the positive C retardation layer may have an anti-reflective effect by interacting with a reverse wavelength dispersive positive A retardation layer. The'nx, ny, nz' are slow axis, fast axis, and refractive index in the thickness direction at a wavelength of 550 nm of the positive C phase difference layer, respectively.

The positive C retardation layer may have an nx of -0.002 to -0.001, ny of -0.002 to -0.001, and nz of 0.001 to 0.002 at a wavelength of 550 nm. In the above range, there may be a control effect of the lateral phase difference by the positive C layer.

The positive C retardation layer may have an in-plane retardation (Re) of 10 nm or less, for example, 4 nm or less, and 0 nm to 4 nm at a wavelength of 550 nm. In the above range, the anti-reflection effect can be achieved by interacting with the reverse wavelength dispersive positive A phase difference layer.

The positive C retardation layer may have a thickness direction retardation (Rth) of -150 nm to -5 nm, for example -100 nm to -5 nm, for example -100 nm to -10 nm, -100 nm to -40 nm at a wavelength of 550 nm. In the above range, there may be a side anti-reflection effect.

The positive C phase difference layer may have a thickness of more than 0 μm and 15 μm or less, preferably 1 μm to 8 μm, more preferably 2 μm to 6 μm. In the above range, it can be used as a positive C phase difference layer, and a thinning effect of the polarizing plate can be obtained.

The positive C phase difference layer may be a non-liquid crystal layer. When the positive C phase difference layer is formed of a liquid crystal, it may be difficult to satisfy Equations 1 and 2 above.

The positive C retardation layer does not have an alignment layer. The positive C retardation layer is formed directly on the reverse wavelength dispersive positive A retardation layer.

The positive C retardation layer may be an unstretched layer. The positive C retardation layer is a coating layer formed by coating and curing the composition for the positive C retardation layer described below, and does not require a stretching process in the manufacturing process.

The positive C retardation layer may be formed of at least one of a cellulose ester or a polymer thereof and an aromatic polymer. The inventor of the present invention was looking for a material capable of producing the effects of Equations 1 and 2 when directly coated on the reverse wavelength dispersive positive A retardation layer among several materials capable of forming a positive C retardation layer. Or the polymer or aromatic polymer was found. Preferably, the positive C retardation layer can be formed of a cellulose ester or a polymer thereof. When the positive C retardation layer is made of liquid crystal by satisfying the above expressions 1 and 2, it is possible to suppress generation of mura due to heat on the side of contrast and to prevent cracks or cracks caused by bending, so that bending reliability can be excellent.

In particular, the cellulose ester or a polymer or an aromatic polymer thereof may improve adhesion between a reverse wavelength dispersive positive A retardation layer and a positive C retardation layer, and lower the interfacial reflectance between the layers to increase the light transmittance of the polarizing plate. In one embodiment, the polarizing plate may have a light transmittance of 41% or more, for example, 42% to 46%.

Cellulose ester refers to the condensation reaction product from the reaction of hydroxyl groups on cellulose with carboxylic acid groups of carboxylic acids. Cellulose esters can be substituted position-wise or randomly. Position selectivity can be measured by determining the relative degree of substitution in C6, C3, C2 on cellulose esters by carbon 13 NMR. Cellulose esters can be prepared by conventional methods by contacting the cellulosic solution with one or more C1 to C20 acylating agents for a contact time sufficient to provide a cellulose ester with the desired degree of substitution and degree of polymerization. Preferred acylating agents are one or more C1 to C20 straight or branched chain alkyl or aryl carboxylic anhydrides, carboxylic acid halides, diketones, or acetoacetic acid esters. Examples of anhydrides of carboxylic acids include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, hexanoic anhydride, 2-ethylhexanoic anhydride, nonanoic anhydride, lauric anhydride, palmitic anhydride, Stearic anhydride, benzoic anhydride, substituted benzoic anhydride, phthalic anhydride, isophthalic anhydride. Examples of carboxylic acid halides include acetyl, propionyl, butyryl, hexanoyl, 2-ethylhexanoyl, lauroyl, palmitoyl, benzoyl, substituted benzoyl, and stearoyl chloride. Examples of acetoacetic acid esters may include methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, butyl acetoacetate, tertiary butyl acetoacetate. Most preferred acylating agents are C2 to C9 straight or branched chain alkyl carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, 2-ethylhexanoic anhydride, nonanoic anhydride, stearic anhydride, and the like.

Preferred examples of cellulose esters may include, but are not limited to, one or more of cellulose acetate (CA), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB). One or more of the cellulose acetate (CA), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB) can easily reach Equations 1 and 2 and suppress the thinning effect and heat generation of mura can do.

The positive C retardation layer may further include an additive having an aromatic fused ring in addition to the cellulose ester or a polymer thereof or an aromatic polymer. The additive may serve to control the Rth expression rate and wavelength dispersion of the positive C retardation layer. The aromatic fused ring may include naphthalene, anthracene, phenanthrene, pyrene, Formula 1 or Formula 2 below. Examples of the additive may include, but are not limited to, 2-naphthyl benzoate, 2,6-naphthalene dicarboxylic acid diester of Formula 3, naphthalene, abietic acid ester of Formula 4 below, and the like:

<Formula 1>

<Formula 2>

<Formula 3>

(In Formula 3, R is C1 to C20 alkyl or C6 to C20 aryl, n is an integer from 0 to 6)

<Formula 4>

(In the above formula 4, R is C1 to C20 alkyl or C6 to C20 aryl)

At least one of the cellulose ester or its polymer and aromatic polymer has a linear change in the thickness direction retardation (Rth) at a wavelength of 550 nm according to the thickness of the positive C retardation layer, thereby realizing the retardation in the manufacturing process during manufacture of the positive C retardation layer. For high reliability.

The positive C retardation layer may be formed of a composition for a positive C retardation layer comprising at least one of the aforementioned cellulose ester or a polymer or aromatic polymer thereof.

The composition for the positive C retardation layer may include a solvent capable of improving the coatability of the composition in addition to the cellulose ester or a polymer or aromatic polymer described above. The solvent may include, but is not limited to, organic solvents commonly used by those skilled in the art.

The solid content in the composition for the positive C retardation layer may be included in an amount of 0.1% to 20% by weight, preferably 5% to 20% by weight, and 9% to 15% by weight. In this range, the interface between the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer may be uniform.

The composition for the positive C retardation layer may further include additives such as plasticizers, stabilizers, UV absorbers, block inhibitors, slip agents, lubricants, dyes, pigments, and delay improvers.

An adhesive layer, an adhesive layer, or a point adhesive layer is additionally formed on the other surface of the positive C retardation layer, that is, the surface that does not directly contact the reverse wavelength dispersion positive A retardation layer, thereby adhering the polarizing plate to an adherend, for example, an OLED panel, a liquid crystal panel, etc. I can do it.

Hereinafter, the polarizing film of the present invention will be described.

The polarizing film may include a polyvinyl alcohol-based polarizer prepared by uniaxially stretching a polyvinyl alcohol-based film, or a polyene-based polarizer produced by dehydrating a polyvinyl alcohol-based film. The polarizing film may have a thickness of 5 μm to 40 μm. In the above range, it can be used for a display device.

A protective layer may be additionally laminated on at least one surface of the polarizing film. The protective layer protects the polarizing film, thereby increasing the reliability of the polarizing plate and increasing the mechanical strength of the polarizing plate.

The protective layer can include one or more of an optically transparent, protective film or protective coating layer. The protective film includes a cellulose ester-based resin including triacetyl cellulose (TAC), a cyclic polyolefin-based resin including amorphous cyclic polyolefin (COP), a polycarbonate-based resin, polyethylene terephthalate (PET), and the like. Poly(meth)acrylate-based resins including polyester-based resins, polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic-polyolefin-based resins, and polymethylmethacrylate resins A film formed of at least one of a resin, a polyvinyl alcohol-based resin, a polyvinyl chloride-based resin, and a polyvinylidene chloride-based resin may be included, but is not limited thereto. The protective coating layer may be formed of an active energy ray-curable resin composition comprising an active energy ray-curable compound and a polymerization initiator. The active energy ray-curable compound may include at least one of a cationically polymerizable curable compound, a radically polymerizable curable compound, a urethane resin, and a silicone resin.

A functional coating layer may be additionally formed on the other side of the polarizing film. The functional coating layer may include, but is not limited to, one or more of a primer layer, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low reflection layer, and an ultra low reflection layer.

Hereinafter, a polarizing plate according to another embodiment of the present invention will be described.

The polarizing plate includes a polarizing film and an inverse wavelength dispersive positive A retardation layer and a positive C retardation layer sequentially stacked on a lower surface of the polarizing film, and the inverse wavelength dispersing positive A retardation layer is direct to the positive C retardation layer. And a stack of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer satisfies Equations 1 and 2, and the reverse wavelength dispersive positive A retardation layer dissolves when contacted with an organic solvent. And/or a polymer film or liquid crystal film that is susceptible to erosion.

In one embodiment, the reverse wavelength dispersive positive A retardation layer may have an in-plane retardation change (ΔRe) according to Equation 5 below 5 nm, for example, 20 nm to 200 nm, 20 nm to 150 nm:

[Equation 5]

In-plane phase difference change amount (△Re) = |Re[0]-Re[1]|

(Equation 5 above,

Re[0] is the wavelength of the MD x TD x (3cm x 3cm x 50㎛) inverse wavelength dispersibility positive A phase difference layer Re (at:550nm wavelength 550nm)

Re[1] is added dropwise with 1 drop of methyl ethyl ketone to the specimen of the reverse wavelength dispersive positive A phase difference layer at 25° C., and after standing for 1 hour, Re (unit) at a wavelength of 550 nm of the specimen of the reverse wavelength dispersibility positive A phase difference layer. :nm).

The 1 drop may mean 0.001ml to 10ml, but is not limited thereto.

The reverse wavelength dispersive positive A retardation layer may include the polymer film of the reverse wavelength dispersive positive A retardation layer described above.

The positive C retardation layer is formed of a composition for a positive C retardation layer comprising at least one of a cellulose ester or a polymer thereof, an aromatic polymer, and a solvent, the solvent being a ketone solvent such as methyl isopropyl ketone (MIPK), acetone, propylene Ether-based solvents such as glycol methyl ether (PGME) and methyl tertiary butyl ether (t-BME), and at least one solvent of propylene glycol methyl ether acetate (PGMEA) may be used, but is not limited thereto. The solvent may secure adhesion between a reverse wavelength dispersive positive A retardation layer and a positive C retardation layer.

In one embodiment, the reverse wavelength dispersion positive A retardation layer may further include a buffer layer on one surface in contact with the positive C retardation layer. The buffer layer may be a solvent erosion layer formed by eroding a portion of the reverse wavelength dispersive positive A retardation layer when coating the composition for the positive C retardation layer on the reverse wavelength dispersive positive A retardation layer.

The buffer layer may have a thickness of 10 μm or less. In the above range, the adhesion between the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer can be increased. The buffer layer may have an in-plane retardation Re of 5 nm or less, preferably 0 nm or more and 3 nm or less at a wavelength of 550 nm. In the above range, the reverse wavelength dispersibility positive A phase difference layer and the positive C phase difference layer may serve as a buffer layer without affecting the phase difference of each. The buffer layer may occupy 1% to 20% of the total thickness of the reverse wavelength dispersive positive A retardation layer. In the above range, it is possible to increase the adhesion while realizing the phase difference of the reverse wavelength dispersibility positive A phase difference layer.

The buffer layer may be present in the solvent of 1ppm to 30,000ppm, preferably 300ppm to 10,000ppm. In the above range, when left at high temperature or high temperature and high humidity for a long time, deformation of the polarizing plate due to solvent volatilization, reverse wavelength dispersibility positive A retardation layer, or positive C retardation layer may be prevented, and adhesion may not be affected.

In one embodiment, the solvent may be a mixture of a ketone-based solvent and an ether-based solvent. The ketone solvent is 40% to 70% by weight in the mixture, preferably 45% to 55% by weight, and the ether solvent is 30% to 60% by weight in the mixture, preferably 45% to 55% by weight It may be included in weight percent. In the above range, the adhesion between the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer may be good.

Preferably, the solvent may include methyl ethyl isopropyl ketone alone, a mixture of methyl isopropyl ketone and propylene glycol methyl ether, or a mixture of acetone and propylene glycol methyl ether. One or more of methyl isopropyl ketone and acetone in the mixture may include 40% to 70% by weight, preferably 45% to 55% by weight. Propylene glycol methyl ether in the mixture may include 30% to 60% by weight, preferably 45% to 55% by weight. In the above range, the adhesion between the reverse wavelength dispersive positive A retardation layer and the positive C layer may be good.

Hereinafter, the optical display device of the present invention will be described.

The optical display device of the present invention may include one or more of the polarizing plates of the present invention.

In one embodiment, the optical display device may include a liquid crystal display device, a light emitting device display device, and preferably a light emitting device display device. The liquid crystal display device may include a liquid crystal display device having liquid crystal for IPS (In Place Switching). The light emitting device display device includes an organic or organic light emitting device, and includes, for example, light emitting diodes (LEDs), organic light emitting diodes (OLEDs), quantum dot light emitting diodes (QLEDs), and phosphors. It may mean a light emitting device.

Hereinafter, the configuration and operation of the present invention through a preferred embodiment of the present invention will be described in more detail. However, the following examples are intended to help the understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Below, the phase difference was measured using Axoscan.

Example 1

PC (polycarbonate)-based film (Konica minolta, modified with reverse wavelength dispersive positive A retardation layer, Re = 140 nm, Rth = 85 nm, NZ = 1.1, Re (450)/Re (550) = 0.85, Re at wavelength 550 nm (650)/Re(550)=1.04, thickness=55 μm) was used. The reverse wavelength dispersive positive A phase difference layer had a ΔRe of 5 nm or more by Equation 5 above.

A composition for positive C retardation layer having a solid content of 10% by weight was prepared by uniformly mixing VM (Eastman, cellulose acetate-based) and solvent MIPK (methyl isopropyl ketone). The "solid content" means the weight ratio of the content of the VM in the composition for the positive C retardation layer.

The polyvinyl alcohol film was stretched 3 times at 60°C, adsorbed iodine, and then stretched 2.5 times in a boric acid aqueous solution at 40°C to prepare a polarizer (thickness = 12 µm).

A triacetylcellulose (TAC) film (KC2UAW, Konica Minolta Opto, Inc.) was attached to the upper surface of the polarizer, and the reverse wavelength dispersive positive A retardation layer was attached to the lower surface of the polarizer.

A positive C retardation layer (thickness = 3 μm) was coated on the lower surface of the reverse wavelength dispersive positive A retardation layer by directly coating the prepared composition for a positive C retardation layer to a predetermined thickness and drying (or curing) at 60° C. for 3 minutes. , Re = 0 nm, Rth = -70 nm) at a wavelength of 550 nm, TAC film-polarizer-reverse wavelength dispersibility positive A retardation layer-positive C retardation layer was sequentially stacked polarizing plate was prepared.

Example 2

In Example 1, a modified PC-based film (Konica minolta, Re = 140 nm, Rth = 85 nm, Re (450) / Re (550) = 0.85, Re (650) / Re (550) = 1.04, NZ at a wavelength of 550 nm = 1.1, thickness = 55 μm), instead of reverse wavelength dispersive positive A liquid crystal film (Merck, Re = 140 nm at wavelength 550 nm, Rth = 70 nm, Re (450) / Re (550) = 0.83, Re (650) /Re (550) = 1.04, thickness = 3㎛) was prepared in the same manner as in Example 1, except for using a polarizing plate. The reverse wavelength dispersibility positive A liquid crystal film had ΔRe of the above formula 5 of 5 nm or more.

Example 3

A polarizing plate was manufactured in the same manner as in Example 1, except that the coating thickness of the positive C retardation layer was changed in Example 1. At this time, the positive C retardation layer has a thickness: 5 μm and Re=0 nm and Rth= -100 nm at a wavelength of 550 nm.

Comparative Example 1

A polarizer was prepared in the same manner as in Example 1.

A polyethylene terephthalate (PET) film with a release film was directly coated with the same composition for the positive C retardation layer as in Example 1 to a predetermined thickness and dried (or cured) at 60° C. for 3 minutes to form a positive C retardation layer on the release film ( Re = 0 nm, Rth = -70 nm) was formed at a thickness of 3 μm and a wavelength of 550 nm.

A triacetylcellulose (TAC) film (KC2UAW, Konica Minolta Opto, Inc.) was adhered to the upper surface of the prepared polarizer, and the reverse wavelength dispersive positive A phase difference layer as in Example 1 was adhered to the lower surface of the polarizer.

TAC film-polarizer-reverse wavelength dispersive positive A retardation layer by adhering the laminate of the prepared positive C retardation layer and release film to the lower surface of the reverse wavelength dispersive positive A retardation layer with an acrylic adhesive and peeling the release film -Acrylic adhesive layer-A positive C phase difference layer (cellulose acetate-based) was sequentially formed polarizing plate.

Comparative Example 2

A polarizing plate was manufactured in the same manner as in Example 1, except that the positive C retardation layer was formed of a homeotropic liquid crystal (Merck). TAC film-polarizer-reverse wavelength dispersive positive A retardation layer by sequentially coating the alignment film 2 µm, liquid crystal 0.5 µm on the PET film, laminating the adhesive layer on the reverse wavelength dispersibility positive A retardation layer and transferring the coated liquid crystal -A polarizing plate in which positive C retardation layers (homeotropic liquid crystals) were sequentially stacked was prepared. The homeotropic liquid crystal layer is a positive C retardation layer, and has a thickness = 0.5 µm and Re = 0 nm and Rth = -70 nm at a wavelength of 550 nm.

Comparative Example 3

In Example 1, the composition for the positive C retardation layer was changed to a methyl methacrylate-based composition, and the thickness of the positive C retardation layer was changed as shown in Table 1 below. -Polarizer-Reverse wavelength dispersibility Positive A retardation layer-A positive C retardation layer (methyl methacrylate-based) was sequentially laminated polarizing plate was prepared. The methyl methacrylate-based layer is a positive C retardation layer, and has a thickness of 40 µm and Re = 0 nm and Rth = -70 nm at a wavelength of 550 nm.

Reference Example 1

The inverse wavelength dispersion positive A retardation layer of Example 1 was left at 85° C. and the thickness direction retardation (Rth) was measured at a wavelength of 550 nm according to the standing time. The results are shown in FIG. 1. Referring to FIG. 1, the reverse wavelength dispersion positive A retardation layer rapidly increased in a thickness direction retardation (Rth) after standing at 85° C. for 24 hours. In addition, referring to FIG. 1, the reverse wavelength dispersibility positive A phase difference layer of Example 1 was 7 nm of Equation 3 when left at 85° C. for 500 hours.

Reference Example 2

The reverse wavelength dispersion positive A retardation layer of Example 1 was measured at a thickness of 550 nm according to the standing time while standing at 60° C. and 95% relative humidity. The results are shown in FIG. 2. Referring to FIG. 2, the reverse wavelength dispersive positive A phase difference layer rapidly increased Rth after standing at 60° C. and 95% relative humidity for 24 hours. In addition, referring to FIG. 2, the reverse wavelength dispersibility positive A phase difference layer of Example 1 was about 2.5 nm when the Rth change in Equation 4 was left at 60° C. and 95% relative humidity for 500 hours.

The reverse wavelength dispersibility positive A liquid crystal film of Example 2 was also measured in the same manner as in Reference Example 1 and Reference Example 2 above. The results are shown in Table 1 below.

The physical properties of Table 1 below were evaluated for the laminate and polarizing plate of the reverse wavelength dispersibility A phase difference layer and the positive C phase difference layer prepared in Examples and Comparative Examples. The results are shown in Tables 1, 3 and 4 below.

(1) Durability 1 (unit: nm): Reverse wavelength dispersibility A layered phase difference was measured at a wavelength of 550 nm of the layered product while leaving the layered product of the A phase difference layer and the positive C phase difference layer at 85°C. The thickness direction retardation at 0 hours and the thickness direction retardation after 500 hours were determined. The amount of retardation in the thickness direction |Rth[0]-Rth[500]| was calculated using Equation 1 above.

(2) Durability 2 (unit: nm): The amount of retardation in the thickness direction of Equation 2 in the same manner as in (1) except that the laminate was left at 60°C and 95% relative humidity for 500 hours. Rth[0] -Rth[500]| was calculated.

(3) Flexibility (unit: piece): The polarizing plates of Examples and Comparative Examples were wound in a state in which the TAC film in the polarizing plate was in contact with a jig having a radius of curvature of 1.5 mm, and allowed to stand at 25° C. for 1 minute, followed by reverse wavelength dispersion in the polarizing plate It was evaluated whether cracks and/or cracks occurred in the A retardation layer and the positive C retardation layer. Experimented with a total of 20 polarizing plates, and the number of polarizing plates having double cracks and/or cracks was recorded.

(4) Adhesion (unit: number): The adhesion was evaluated for the polarizing plates prepared in Examples and Comparative Examples. The polarizing plate was cut into a square shape of length x width (10 cm x 10 cm), and an adhesive tape (Nichi Ichibang) was attached to the positive C layer side of the polarizing plate. The back-wave dispersion dispersive positive A phase difference layer was cut into 10 rows and 10 rows. When the adhesive tape was detached, the number of detached specimens among 100 specimens was evaluated. The larger the adhesion between the positive C retardation layer and the reverse wavelength dispersibility positive A retardation layer, the more the 100 specimens are detached.

		Example			Comparative example
		One	2	3	One	2	3
Reverse wavelength dispersion +A	material	Denatured PC film	LCD film	Denatured PC film	Denatured PC film	Denatured PC film	Denatured PC film
	△Rth ＠85℃ in Equation 3, 500HR	7	9	7	7	7	7
	△Rth of Equation 4 ＠60℃,95%, 500HR	2.5	3.0	2.5	2.5	2.5	2.5
+C phase difference layer		Cellulose acetate system	Cellulose acetate system	Cellulose acetate system	Cellulose acetate system	Homeotropic LCD	Methyl methacrylate system
+C phase difference layer thickness (㎛)		3	3	5	3	0.5	40
Durability 1 (Equation 1, nm)		One	3	One	6	8	7
Durability 2 (Equation 2, nm)		One	2	0.5	5	7	6
Flexural reliability		0	0	0	0	4	5
Adhesion		0	0	0	0	0	0

As shown in Table 1, when the polarizing plate of the present invention is left at high temperature and high temperature and high humidity for a long period of time, the amount of phase difference change is low, so durability and reliability are excellent, and cracks can be prevented from being cracked even by bending. The adhesion between the wavelength-dispersive positive A retardation layer and the positive C retardation layer is excellent and has a thinning effect. Referring to FIGS. 3 and 4, it can be seen that the amount of change in Rth of the reverse wavelength dispersive positive A retardation layer and positive C retardation layer was very low according to 24 hours, 120 hours, 250 hours, and 500 hours.

On the other hand, Comparative Example 2 and Comparative Example 3 without the positive C retardation layer of the present invention, Comparative Example 1 in which the positive C retardation layer of the present invention is not formed directly on the reverse wavelength dispersive positive A retardation layer is described above. All the effects of the present invention could not be obtained.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (17)

1. A polarizing film and a reverse wavelength dispersive positive A retardation layer and a positive C retardation layer formed on the lower surface of the polarizing film,

   The reverse wavelength dispersion positive A retardation layer is formed directly on the positive C retardation layer,

   A laminate of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer satisfies Expression 1 and Expression 2 below:

   [Equation 1]

   0nm ≤ |Rth[0]-Rth[500]| ≤ 5nm

   (Equation 1 above,

   Rth[0] is the initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the laminate,

   Rth [500] is the phase difference (unit: nm) in the thickness direction at a wavelength of 550 nm of the laminate when the laminate is left at 85° C. for 500 hours,

   [Equation 2]

   0nm ≤ |Rth[0]-Rth[500]| ≤ 2nm

   (In Equation 2 above,

   Rth[0] is the initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the laminate,

   Rth[500] is the phase difference (unit: nm) in the thickness direction at a wavelength of 550 nm of the laminate when the laminate is left at 60°C and 95% relative humidity for 500 hours.
2. The polarizing plate according to claim 1, wherein the reverse wavelength dispersive positive A phase difference layer has a thickness direction retardation change (ΔRth) according to Equation 3 greater than 5 nm:

   [Equation 3]

   Amount of retardation change in thickness direction (△Rth) = |Rth[0]-Rth[500]|

   (Equation 3 above,

   Rth[0] is an initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the reverse wavelength dispersive positive A retardation layer,

   Rth[500] is the thickness direction retardation (unit: nm) at a wavelength of 550 nm of the reverse wavelength dispersive positive A retardation layer when the reverse wavelength dispersive positive A retardation layer is left at 85° C. for 500 hours.
3. The polarizing plate of claim 1, wherein the reverse wavelength dispersive positive A retardation layer has a thickness direction retardation change amount (ΔRth) according to Equation 4 below 2 nm:

   [Equation 4]

   Amount of retardation change in thickness direction (△Rth) = |Rth[0]-Rth[500]|

   (In the above equation 4,

   Rth[0] is an initial thickness direction retardation (unit: nm) at a wavelength of 550 nm of the reverse wavelength dispersive positive A retardation layer,

   Rth[500] is a thickness direction phase difference at a wavelength of 550 nm of the reverse wavelength dispersive positive A phase difference layer when the reverse wavelength dispersive positive A phase difference layer is left at 60°C and 95% relative humidity for 500 hours (unit: nm). .
4. The polarizing plate according to claim 1, wherein the reverse wavelength dispersive positive A retardation layer has an in-plane retardation change (ΔRe) of 5 nm or more according to Equation 5 below:

   [Equation 5]

   In-plane phase difference change amount (△Re) = |Re[0]-Re[1]|

   (Equation 5 above,

   Re[0] is the wavelength of the MD x TD x (3cm x 3cm x 50㎛) inverse wavelength dispersibility positive A phase difference layer Re (at:550nm wavelength 550nm)

   Re[1] is added dropwise with 1 drop of methyl ethyl ketone to the specimen of the reverse wavelength dispersible positive A retardation layer at 25° C., and after standing for 1 hour, Re(1) at wavelength 550nm of the specimen of the reverse wavelength dispersible positive A retardation layer. Unit:nm))).
5. According to claim 1, The reverse wavelength dispersion positive A phase difference layer is a non-modified polycarbonate-based resin, cyclic olefin polymer resin, modified polycarbonate-based resin, isosorbide-based resin, cellulose-based resin, fluorene-based resin, A polarizing plate comprising a polymer film formed of at least one of polyester resins.
6. The polarizing plate of claim 1, wherein the reverse wavelength dispersive positive A phase difference layer includes a liquid crystal layer formed of at least one liquid crystal among nematic liquid crystal, smectic liquid crystal, and cholesteric liquid crystal.
7. The polarizing plate of claim 1, wherein the reverse wavelength dispersive positive A retardation layer has an nx of 0.001 to 0.002, ny of -0.002 to -0.001, and nz of -0.002 to -0.001 at a wavelength of 550 nm.
8. The polarizing plate according to claim 1, wherein the positive C retardation layer is a non-liquid crystal layer and has no alignment layer.
9. The polarizing plate of claim 1, wherein the positive C phase difference layer comprises a coating layer formed of a composition comprising at least one of a cellulose ester or a polymer or an aromatic polymer.
10. The polarizing plate of claim 9, wherein the cellulose ester comprises at least one of cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate.
11. The polarizing plate of claim 1, wherein the positive C retardation layer has an nx of -0.002 to -0.001, ny of -0.002 to -0.001, and nz of 0.001 to 0.002 at a wavelength of 550 nm.
12. The polarizing plate of claim 1, wherein a stack of the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer has an Rth of -50 nm to 50 nm at a wavelength of 550 nm.
13. The polarizing plate of claim 1, wherein the reverse wavelength dispersive positive A retardation layer and the positive C retardation layer are sequentially formed on a lower surface of the polarizing film.
14. The polarizing plate of claim 1, wherein a buffer layer is further formed on one surface of the reverse wavelength dispersive positive A retardation layer in contact with the positive C retardation layer.
15. The polarizing plate according to claim 14, wherein the buffer layer has an in-plane retardation Re of 5 nm or less at a wavelength of 550 nm.
16. The polarizing plate of claim 14, wherein the buffer layer occupies 1% to 20% of the total thickness of the reverse wavelength dispersive positive A phase difference layer.
17. An optical display device comprising the polarizing plate of any one of claims 1 to 16.

Images