KR20160091014A - Polarizer and preparing method for the same - Google Patents

Abstract

The present invention relates to a polarizer and a manufacturing method thereof. More specifically, the present invention relates to a polarizer which has a minimized color variation even when the polarizer is exposed in a high temperature condition for a long time by satisfying a mathematical formula 1, and a manufacturing method thereof. The mathematical formula 1 is 0.7<=A700/A480<=1.0.

Description

[0001] POLARIZER AND PREPARING METHOD FOR THE SAME [0002]

The present invention relates to a polarizer and a method of manufacturing the same.

Polarizing plates used in various image display devices such as a liquid crystal display (LCD), an electroluminescence (EL) display, a plasma display (PDP), a field emission display (FED) and an OLED are generally made of polyvinyl alcohol alcohol, PVA) film comprises a polarizer in which an iodine compound or a dichroic polarizing material is adsorbed and oriented, a polarizer protective film is laminated on one side of the polarizer, and a polarizer protective film, a liquid crystal cell Layer structure in which a pressure-sensitive adhesive layer and a release film are laminated in this order.

The polarizer constituting the polarizing plate is required to have a high transmittance and a high degree of polarization in order to provide an image excellent in color reproducibility by being applied to an image display apparatus. In addition, as the application of the flat panel display device to various fields of the flat panel display device is expanded and the tendency of enlargement becomes clearer, various image display devices such as a liquid crystal display device may be used at a high temperature for a long time, And the demand for improvement in durability has also been increased. As a result, the conditions for the performance of the polarizer have become very strict. In addition, image display devices having characteristics suitable for various environments and applications are currently in demand, and optical durability including color change under high temperature and high humidity conditions and high contrast through high transmission are required.

Korean Patent Laid-Open Publication No. 2009-70085 discloses a method of manufacturing a polarizer, but fails to provide an alternative to the above problem.

Korea Patent Publication No. 2009-70085

It is an object of the present invention to provide a polarizer having improved color durability and an excellent polarization degree.

It is still another object of the present invention to provide a method for producing a polarizer having improved color durability and an excellent polarization degree.

1. A polarizer comprising:

[Equation 1]

0.7? A700 / A480? 1.0

(In the formula, A700 is defined by the following formula (2)

&Quot; (2) &quot;

A ₇₀₀ = - Log ₁₀ {(T _{MD, 700} T _{TD, 700} ) / 10000}

T _{MD, 700} is a parallel transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,

T _{TD, 700} is the orthogonal transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged so that their absorption axes are perpendicular to each other,

A480 is defined by the following equation (3)

&Quot; (3) &quot;

A480 = - Log ₁₀ {(T _{MD, 480} * T _{TD, 480} ) / 10000}

T _{MD, 480} is a parallel transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,

T _{TD, 480} is the orthogonal transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged so that their absorption axes are orthogonal).

2. The polarizer of claim 1, wherein the polarizer comprises a metal salt.

3. The polarizer according to 2 above, wherein the metal salt is at least one selected from the group consisting of zinc nitrate, copper nitrate, aluminum nitrate, magnesium nitrate and zinc acetate.

4. The polarizer according to 2 above, wherein the metal salt is contained in an amount of 0.1 to 1% by weight based on the total weight of the polarizer.

5. A polarizer comprising at least one protective layer on at least one side of the polarizer of any one of claims 1 to 4.

6. The polarizing plate according to item 5 above, wherein the protective layer is a protective film or a resin coating layer.

7. An image display apparatus comprising the polarizing plate of the fifth aspect.

8. A polarizer-forming film comprising swelling, dyeing, crosslinking, complementing and stretching steps;

The distance between the crystals in the polarizer-forming film in the stretching direction in the staining step is 20 to 40 nm;

The dyeing solution comprises a boric acid compound;

Wherein a crosslinking liquid and a complementary liquid containing a metal salt are used in the crosslinking and the complementary coloring step, respectively.

9. The method of producing a polarizer according to 8 above, wherein said stretching direction is the MD direction.

10. The method of producing a polarizer according to item 8, wherein the boric acid compound is contained in an amount of 0.3 to 5% by weight based on the total weight of the dyeing solution.

11. In the above 8. And the cumulative stretching ratio until the dyeing step is 2.0 to 3.0 times.

12. The method of producing a polarizer according to claim 8, wherein the boric acid compound concentration in the dyeing step is lower than the boric acid compound concentration in the cross-linking step.

13. The method of claim 8, wherein the crosslinking step comprises at least a first and a second crosslinking step.

14. The method of producing a polarizer according to claim 8, wherein the metal salt is at least one selected from the group consisting of zinc nitrate, copper nitrate, aluminum nitrate, magnesium nitrate and zinc acetate.

15. The method of producing a polarizer according to the above 8, wherein the metal salt is contained in an amount of 0.5 to 4% by weight based on the total weight of the crosslinking solution.

16. The method of producing a polarizer according to the above 8, wherein the metal salt is contained in an amount of 0.5 to 4% by weight based on the total weight of the complementary coloring liquid.

17. The polarizer according to the above 8, wherein the polarizer produced by the above production method satisfies the following formula (1): &lt; EMI ID =

[Equation 1]

0.7? A700 / A480? 1.0

(In the formula, A700 is defined by the following formula (2)

&Quot; (2) &quot;

A ₇₀₀ = - Log ₁₀ {(T _{MD, 700} T _{TD, 700} ) / 10000}

T _{MD, 700} is a parallel transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,

T _{TD, 700} is the orthogonal transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged so that their absorption axes are perpendicular to each other,

A480 is defined by the following equation (3)

&Quot; (3) &quot;

A480 = - Log ₁₀ {(T _{MD, 480} * T _{TD, 480} ) / 10000}

T _{MD, 480} is a parallel transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,

T _{TD, 480} is the orthogonal transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged so that their absorption axes are orthogonal).

The polarizer of the present invention has remarkably improved color durability and can minimize the color change even when exposed to a high temperature condition for a long time.

Further, the polarizer of the present invention is excellent in the degree of polarization.

Further, the method of the present invention can produce a polarizer with improved color durability and an excellent degree of polarization.

The present invention relates to a polarizer excellent in color durability and excellent in optical characteristics and satisfactory in color durability by satisfying the formula (1), and a method for producing the same.

Hereinafter, the present invention will be described in detail.

<Polarizer>

PVA-type polarizer is a PVA-I ₅ complex area reduction, under high-temperature and high-humidity conditions comprises a PVA-I ₅ complex as PVA-I ₅ complex is destabilized PVA-I ₅ complex is decomposed to absorb light above 700nm the PVA-I complex content of the region ₅ decreases. As a result, the stability of the dichroic substance complex may be deteriorated and the polarizer may be discolored (durability deterioration).

On the other hand, PVA-based polarizers are PVA-I ₃ complex also comprises, PVA-I ₃ complex contributes to the degree of polarization expressed.

Therefore, it is considered necessary to appropriately maintain the content of the PVA-I ₅ complex and the PVA-I ₃ complex in the polarizer.

However, in the production of polarizers, iodine is added as an iodine molecule or an iodine salt and converted to I ₃ ^- or I ₅ ^- according to the specific environment or conditions in the chemical solution (dyeing bath, crosslinking bath and / or auxiliary bath) It is difficult to directly control the content (concentration) of I ₃ ^- or I ₅ ^- .

The inventors have found that A700 of the polarizer of the present invention can be associated with PVA-I ₅ complex content, A480, while identifying that there is associated with the PVA-I ₃ complex content, particularly of the A700 and A480 ratio of the polarizer is excellent in keeping the degree of polarization And the PVA-I ₅ complex content and the PVA-I ₃ complex content which prevent discoloration even under high-temperature and high-humidity conditions are indicative of the present invention.

The polarizer of the present invention satisfies the following formula (1), thereby maintaining the polarization degree, optical characteristics and durability very excellent.

[Equation 1]

0.7? A700 / A480? 1.0

(In the formula, A700 is defined by the following formula (2)

&Quot; (2) &quot;

A ₇₀₀ = - Log ₁₀ {(T _{MD, 700} T _{TD, 700} ) / 10000}

T _{MD, 700} is a parallel transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,

T _{TD, 700} is the orthogonal transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged so that their absorption axes are perpendicular to each other,

A480 is defined by the following equation (3)

&Quot; (3) &quot;

A480 = - Log ₁₀ {(T _{MD, 480} * T _{TD, 480} ) / 10000}

T _{MD, 480} is a parallel transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,

T _{TD, 480} is the orthogonal transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged so that their absorption axes are orthogonal).

If the value of A700 / A480 of the polarizer is less than 0.7, the degree of polarization may decrease. If the value of A700 / A480 is more than 1, the orthogonal b may become blue and become defective.

The fulfillment of the above equation (1) of the polarizer can be achieved by various methods. For example, the characteristics of the polarizer-forming film, the use of a crosslinking solution or a complementary solution containing a metal salt in the production of the polarizer, the concentration of the boric acid compound in the crosslinking solution or the complementary solution, the temperature, the concentration of the boric acid compound in the dyeing solution, And the like, for example.

Specifically in the case of using a double metal salt as an example, the use of cross-linking solution and the complementary color solution containing the manufacture of the polarizer metal salt, a metal salt and PVA-I ₅ complex is chemically bonded the PVA-I ₅ complex stabilized by being the PVA-I ₅ complexes do not decompose it is possible to suppress the occurrence enemy sides.

If the metal salt is capable of preventing the decomposition of the PVA-I complex to the _{5 PVA-5} I complex and a chemical bond may be used without particular limitation. Specific examples thereof include zinc nitrate, copper nitrate, aluminum nitrate, magnesium nitrate, zinc acetate and the like. Of these, zinc nitrate is preferable in terms of improving durability.

The metal salt may be included in an amount of 0.1 to 1% by weight based on the total weight of the polarizer. The color durability and optical characteristics of the polarizer can be maintained within the above range.

&Lt; Polarizer Manufacturing Method >

The present invention also provides a method of manufacturing a polarizer according to the present invention described above.

The method for producing a polarizer according to the present invention includes a step of swelling, dyeing, crosslinking, complementing and stretching a film for forming a polarizer, wherein the distance between crystals in the film for polarizer formation in the stretching direction in the dyeing step is 20 to & 40 nm, and the dyeing solution contains a boric acid compound. By using a crosslinking solution and a complementary solution containing a metal salt in the crosslinking and complementary steps, a polarizer having a minimized color change can be manufactured even when exposed to high temperature conditions for a long time have.

Generally, when iodine and iodine salts are added to a dyeing solution in the dyeing step during the production process of the polarizer, there is a problem that the polarization degree can not be lowered when the transmittance is made high. In addition, Is included in the crosslinking liquid and the crosslinking step is carried out, the stability of the dichroic complex is deteriorated and the color of the polarizer is changed or the durability is deteriorated.

However, in the polarizer producing method of the present invention, the distance between the crystals in the film (polymer) for polarizer formation in the stretching direction in the dyeing step is 20 to 40 nm and the dyeing solution contains a boric acid compound, The initial polarization degree is improved by improving the retention time of the boric acid compound before execution and increasing the complex formation rate of iodine, which is a dichroic substance, in the film for forming a polarizer. When the distance between the crystals is out of the above range, or when the dye solution contains no boric acid compound, problems such as discoloration of the polarizer, deterioration of durability, and initial polarization degree may occur.

In addition, since the method for producing the polarizer of the present invention uses a crosslinking liquid and a complementary liquid containing a metal salt in the crosslinking and complementary phases, the metal salt and the dichroic material complex are chemically bonded to each other to stabilize the dichroic material complex, And the occurrence of enemy sides is suppressed.

Therefore, according to the polarizer manufacturing method of the present invention, it is possible to manufacture a polarizer in which the color change is minimized even when exposed to a high temperature condition for a long time.

Hereinafter, one embodiment of the polarizer manufacturing method of the present invention will be described in more detail. Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention should not be construed as being limited thereto.

The number of repetitions of each production step of the polarizer of the present invention, the process conditions, and the like are not particularly limited as long as they do not deviate from the object of the present invention, and the stretching step may be performed in an independent step or may be performed in one step or more of swelling, Or may be performed simultaneously.

The polarizer-forming film is not particularly limited as long as it is a film which can be dyed with a dichroic substance, that is, iodine or the like, for example, a polyvinyl alcohol film, a partially saponified polyvinyl alcohol film; A hydrophilic polymer film such as a polyethylene terephthalate film, an ethylene-vinyl acetate copolymer film, an ethylene-vinyl alcohol copolymer film, a cellulose film, a partially saponified film thereof and the like; Or a dehydrated polyvinyl alcohol film, a dehydrochloric acid-treated polyvinyl alcohol film, and the like. Of these, a polyvinyl alcohol-based film is preferred because it has an excellent effect of enhancing the uniformity of the degree of polarization in the plane and is excellent in dye affinity for iodine.

Swelling step

The swelling step is carried out by immersing the unstretched polarizer forming film in a swelling tank filled with a swelling aqueous solution before dyeing to remove impurities such as dust and anti-blocking agent deposited on the surface of the polarizing film, Is a step for improving physical properties of the polarizer by swelling to improve the drawing efficiency and to prevent uneven dyeing.

As the swelling aqueous solution, water (pure water, deionized water) can be used alone, and a small amount of glycerin or potassium iodide can be added to improve the processability of the polymer film.

Glycerin and potassium iodide, the content thereof is not particularly limited and may be 5 wt% or less and 10 wt% or less, respectively, of the total weight of the aqueous swelling solution.

The temperature of the swelling bath is not particularly limited and may be, for example, 20 to 45 캜, preferably 20 to 40 캜. When the temperature of the swelling bath is within the above range, the stretching and dyeing efficiency is excellent thereafter, and expansion of the film due to excessive swelling can be prevented.

The execution time (swelling tank immersion time) of the swelling step is not particularly limited, and may be, for example, 180 seconds or less, preferably 90 seconds or less. When the swelling bath immersion time is within the above range, excessive swelling and saturation can be suppressed to prevent breakage due to softening of the polarizer forming film and uniformity of adsorption of iodine in the dyeing step to improve the degree of polarization .

The swelling step and the stretching step may be performed together. In this case, the stretching ratio may be about 1.1 to 3.5 times, preferably 1.5 to 3.0 times. Wrinkles may occur when the stretching ratio is less than 1.1 times, and initial optical characteristics may be lowered when the stretching ratio is more than 3.5 times.

Dyeing step

The dyeing step is a step of dipping the film for forming a polarizer into a dyeing bath filled with a dyeing solution containing a dichroic substance, for example, iodine to adsorb iodine to the polarizing film.

In the dyeing step of the present invention, the distance between the crystals in the film for polarizer formation (polymer) in the stretching direction and the crystal is set to 20 to 40 nm, and the dyeing solution contains a boric acid compound, so that the retention time of the boric acid compound the can be improved by increasing the PVA-I and _PVA-5 complex I ₃ complex formation rate for the film forming the polarizer. Accordingly, the color durability of the polarizer can be improved, and the degree of polarization can be improved.

The stretching direction is preferably the MD direction.

The distance between the crystals in the film for forming a polarizer in the stretching direction in the dyeing step and the crystal can be achieved by controlling the kind of the polarizing protective film or the stretching ratio and preferably the cumulative stretching ratio up to the dyeing bath is 2.0 to 3.0 A method of controlling within a range of twice as much can be used.

The kind of the boric acid compound is not particularly limited. For example, the boric acid compound includes boric acid, sodium borate, potassium borate and lithium borate. These may be used alone or in combination of two or more.

The concentration of the boric acid compound in the dyeing solution is not particularly limited, but may be, for example, 0.3 to 5% by weight, preferably 0.5 to 3% by weight, based on the total weight of the dyeing solution. If the concentration of the boric acid compound in the dyeing solution is less than 0.3 wt%, the effect of increasing the iodine complex formation is reduced. If the concentration of the boric acid compound is more than 5 wt%, cutting may occur due to stress increase.

In addition, the boric acid compound in the dyeing solution may be included to have a lower concentration than the boric acid compound added to the crosslinking solution of the crosslinking step to be carried out subsequently.

The dyeing solution may further comprise water, a water-soluble organic solvent or a mixed solvent thereof and iodine. The concentration of iodine in the dyeing solution may be 0.4 to 400 mmol / L, preferably 0.8 to 275 mmol / L, more preferably 1 to 200 mmol / L.

The dyeing solution may further contain iodide as a dissolution aid for improving the dyeing efficiency.

The kind of iodide is not particularly limited and includes, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide and the like , And potassium iodide is preferred in view of high solubility in water. These may be used alone or in combination of two or more.

The content of the iodide is not particularly limited and may be 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total weight of the dyeing solution.

The temperature of the dye bath is not particularly limited and may be, for example, from 5 to 42 캜, preferably from 10 to 35 캜.

The time for immersing the film for forming a polarizer in the dye bath is not particularly limited and may be, for example, 1 to 20 minutes, and preferably 2 to 10 minutes.

In this case, the stretching ratio may be 1.01 to 2.0 times, preferably 1.1 to 1.8 times.

In addition, the cumulative stretching ratio of the polarizer up to the dyeing step including the swelling and stretching steps is preferably 2.0 to 3.0 times. Within the above range, it is possible to solve the problem that the distance between the crystals according to the present invention can be expressed, wrinkles of the film are generated to cause appearance defects, and initial optical characteristics are weak.

Bridging step

The crosslinking step is a step of immersing the stained polarizer-forming film in the crosslinking solution so as to fix the adsorbed iodine molecule so that the dyeability due to the physically adsorbed iodine molecule is not lowered by the external environment.

Since the crosslinking liquid used in the crosslinking step of the present invention includes a metal salt, the metal salt and the dichroic material complex are chemically bonded, so that the mechanism of changing the color of the polarizer can be suppressed and the durability can be improved.

Dichromatic dyes are rarely eluted in a humid environment, but when iodine is unstable, iodine molecules tend to dissolve or sublimate depending on the environment, and sufficient crosslinking reaction is required.

The crosslinking step according to the present invention may be carried out in the first crosslinking step and the second crosslinking step, and the metal salt may be included in the crosslinking solution used in at least one of the crosslinking steps.

The metal salt may be used without particular limitation as described above, and specific examples thereof include zinc nitrate, copper nitrate, aluminum nitrate, magnesium nitrate, zinc acetate, and zinc nitrate is preferable in terms of improving durability.

The concentration of the metal salt in the crosslinking solution is not particularly limited, but may be, for example, 0.5 to 4% by weight of the total weight of the crosslinking solution. If the concentration of the metal salt in the crosslinking solution is less than 0.5% by weight, the color change, especially the effect of inhibiting the occurrence of rusting is not exhibited. If the concentration exceeds 4% by weight, the polarization degree and color defect may occur.

The crosslinking solution of the present invention may further comprise a boric acid compound. By including the boric acid compound, it is possible to improve the crosslinking efficiency, suppress the occurrence of wrinkles of the film during the process, and form an alignment of the dichroic substance to improve the optical characteristics.

The concentration of the boric acid compound in the crosslinking solution is not particularly limited. For example, 1 to 10% by weight, preferably 2 to 6% by weight, based on the total weight of the crosslinking solution. When the concentration of the boric acid compound in the crosslinking solution is less than 1% by weight, the crosslinking effect is reduced and the rigidity of the film may be deteriorated. If it exceeds 10% by weight, the crosslinking may occur due to excessive crosslinking.

The boric acid compound may be the same as that used in the dyeing step.

The crosslinking solution of the present invention may contain an organic solvent mutually soluble together with water and water used as a solvent and may further contain a small amount of iodide in order to prevent the uniformity of the degree of polarization in the plane of the polarizer and the desorption of the iodine .

The iodide may be the same as that used in the dyeing step. The concentration of the iodide is not particularly limited and may be, for example, 0.05 to 15% by weight, preferably 0.5 to 11% by weight %. When the concentration of the iodide in the crosslinking bath satisfies the above range, the iodide ions adsorbed in the dyeing step may escape from the film, or the iodide ions contained in the crosslinking liquid may be prevented from penetrating into the film, thereby suppressing the change of the transmissivity.

The temperature of the crosslinking bath is not particularly limited, but may be, for example, 20 to 70 캜, preferably 40 to 60 캜.

The time for immersing the film for forming a polarizer in the crosslinking tank is not particularly limited and may be, for example, from 1 second to 15 minutes, preferably from 5 seconds to 10 minutes.

The stretching step may be carried out together with the crosslinking step. In this case, the stretching ratio of the first crosslinking step may be 1.4 to 3.0 times, preferably 1.5 to 2.5 times. The stretching ratio of the second crosslinking step may be 1.01 to 2.0 times, preferably 1.2 to 1.8 times.

The cumulative stretching ratio of the first crosslinking step and the second crosslinking step may be 1.5 to 5.0 times, preferably 1.7 to 4.5 times. If the cumulative stretching ratio is less than 1.5 times, the synergistic effect of crosslinking efficiency may be insufficient. If the cumulative stretching ratio is more than 5.0 times, excessive stretching may cause breakage of the film and production efficiency may be deteriorated.

Complementary phase

The complementary color step is a step of adjusting the color by immersing the film having undergone the crosslinking step in a complementary solution containing a metal salt, a boric acid compound and iodide.

The complementary liquid used in the complementary coloring step of the present invention includes a metal salt, whereby the metal salt and the dichroic material complex are chemically bonded to increase the stability of the dichroic material complex, thereby suppressing the color change of the polarizer, Can be improved.

The metal salt may be the same as that used in the crosslinking step.

The concentration of the metal salt in the complementary colorant is not particularly limited, but may be, for example, 0.5 to 4% by weight based on the total weight of the complementary colorant. When the concentration of the metal salt in the complementary coloring liquid is less than 0.5 wt%, the color change, especially the effect of inhibiting the occurrence of rusting, is not exhibited. If the concentration exceeds 4 wt%, the degree of polarization and color defect may occur.

Further, the complementary liquid of the present invention may further include a boric acid compound. The boric acid compound may be the same as that used in the dyeing step.

The concentration of the boric acid compound in the complementary colorant is not particularly limited. For example, 1 to 10% by weight, and preferably 2 to 6% by weight based on the total weight of the complementary coloring liquid. If the concentration of the boric acid compound in the complementary coloring solution is less than 1 wt%, the iodine alignment can not be improved and the effect of suppressing color change and improving durability may be insignificant. If the concentration is more than 10 wt% So that stretching is difficult and the film may be broken.

Preferably, the concentration of the boric acid compound in the complementary liquid of the present invention is lower than the concentration of the boric acid compound in the cross-linking liquid.

The concentration ratio is not particularly limited. For example, the boric acid compound concentration in the crosslinking solution and the boric acid compound concentration in the complementary color solution may have a ratio of 1: 0.4 to 0.8. If the concentration ratio is less than 1: 0.4, the iodine alignment can not be improved and the effect of suppressing color change and improving durability may be insignificant. When the concentration ratio is more than 1: 0.8, So that stretching is difficult and the film may be broken.

The complementary liquid of the present invention may contain an organic solvent that is mutually soluble together with water and water used as a solvent and may contain a small amount of iodide in order to prevent the uniformity of the degree of polarization in the plane of polarizers and the desorption of iodine .

The iodide may be the same as that used in the dyeing step and the crosslinking step. The concentration of the iodide is not particularly limited and may be, for example, 0.05 to 15% by weight, preferably 0.5 To 11% by weight. When the concentration of the iodide of the complementary color liquid satisfies the above range, unadsorbed iodide ions can be adsorbed to the film in the dyeing and crosslinking step, and the iodide ion contained in the complementary color liquid increases penetration into the film, The transmittance can be adjusted.

Preferably, the iodide concentration in the complementary liquid of the present invention is lower than the concentration of iodide in the cross-linking liquid.

In the crosslinking solution, iodide serves to prevent the iodide ions adsorbed in the dyeing step from escaping from the film, but when the iodide is contained in a large amount in the complementary liquid at a level similar to that of the crosslinking liquid, The complex may be decomposed to lower the durability of the polarizer.

The concentration ratio is not particularly limited. For example, the iodide concentration in the crosslinking liquid and the iodide concentration in the complementary colorant may have a ratio of 1: 0.2 to 0.6. If the concentration ratio is less than 1: 0.2, color control can not be performed. If the concentration ratio is more than 1: 0.6, prolonged exposure to heat at a high temperature may degrade the durability of the iodine complex .

The temperature of the complementary color bath is 20 to 70 캜, and the immersion time of the polyvinyl alcohol-based film in the sub-tones may be 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

It is possible to enhance the degree of orientation of the dichroic substance complex by performing stretching of the film for polarizer formation in the complementary coloring stage and thus the polarizer produced by the method of the present invention can minimize decomposition of the complex even after prolonged exposure to high temperatures Excellent color durability.

The stretching may be performed at a stretching ratio of 1.01 to 1.1 times. If the stretching ratio is less than 1.01 times, the effect of improving the degree of orientation of the dichroic substance complex is insignificant. If the stretching ratio is more than 1.1 times, the film may be broken by excessive stretching.

Stretching step

The stretching step may be carried out with at least one of the swelling step, the dyeing step, the crosslinking step and the complementary coloring step, as described above, or may be carried out in air or an inert gas while transferring the film after the steps, May be carried out in an independent stretching step using a stretching tank of a &lt; RTI ID = 0.0 &gt; Alternatively, the unstretched polyvinyl alcohol-based film may be stretched in air or an inert gas before the swelling step, and then the film may be subjected to swelling, dyeing, crosslinking, complementation, washing and drying.

The stretching may be carried out in one step or in two or more steps, but is preferably carried out in two or more steps. The stretching may be carried out by a method such as setting the difference in peripheral speed of the nip roll or the like. Also, like the swelling step, the expander roll, the spiral roll, the crown roll, the cross guider, the bend bar, and the like can be installed in the bath and / or the bath door.

The total cumulative stretching ratio of the present invention is preferably 4.0 to 7.0 times. In the present specification, the term &quot; cumulative stretching ratio &quot; means a value obtained by multiplying the stretching ratio of each step.

Wash step

If necessary, the polarizer of the present invention may further include a washing step after completion of complementary coloring.

In the washing step, the complementary polarizer-forming film is immersed in a water bath filled with a washing liquid to remove unnecessary residues attached to the polarizer-forming film in the previous steps.

The aqueous solution for washing may be water (deionized water), and iodide may be further added thereto. As the iodide, those same as those used in the dyeing step can be used, and among them, sodium iodide or potassium iodide is preferably used. The content of iodide is not particularly limited and may be, for example, 0.1 to 10 parts by weight, preferably 3 to 8 parts by weight, based on the total weight of the aqueous solution for washing.

The temperature of the water bath is not particularly limited and may be, for example, 10 to 60 ° C, and preferably 15 to 40 ° C.

The wash step may be omitted and may be performed each time previous steps such as dyeing step, crosslinking step, stretching step, or complementary step are completed. It may also be repeated one or more times, and the number of repetition is not particularly limited.

Drying step

The drying step is a step of drying the washed polarizer forming film and further improving the orientation of molecules of iodine dissolved in the necking by drying to obtain a polarizer excellent in optical characteristics.

As the drying method, natural drying, air drying, heat drying, microwave drying, hot air drying and the like can be used. Recently, microwave treatment for activating and drying only water in the film has been newly used. Treatment is mainly used.

The temperature at the time of hot air drying is not particularly limited, but it is preferably carried out at a relatively low temperature in order to prevent deterioration of the polarizer. For example, it may be 20 to 90 ° C, preferably 80 ° C or less, Or less.

The execution time of the hot air drying is not particularly limited, and may be, for example, 1 to 10 minutes.

As described above, the polarizer produced by the production method of the present invention exhibits excellent durability and polarization degree, and satisfies the following formula (1).

[Equation 1]

0.7? A700 / A480? 1.0

(In the formula, A700 is defined by the following formula (2)

&Quot; (2) &quot;

A ₇₀₀ = - Log ₁₀ {(T _{MD, 700} T _{TD, 700} ) / 10000}

T _{MD, 700} is a parallel transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,

T _{TD, 700} is the orthogonal transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged so that their absorption axes are perpendicular to each other,

A480 is defined by the following equation (3)

&Quot; (3) &quot;

A480 = - Log ₁₀ {(T _{MD, 480} * T _{TD, 480} ) / 10000}

T _{MD, 480} is a parallel transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,

T _{TD, 480} is the orthogonal transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged so that their absorption axes are orthogonal).

As described above, if the value of A700 / A480 of the polarizer is less than 0.7, the degree of polarization may be lowered. If the value of A700 / A480 is more than 1, the orthogonal b may become blue and become defective. Further, to satisfy the range of the equation (1) by a metal salt prevents the decomposition of the PVA-I ₅ complex and chemically bonded to PVA-I ₅ complexes contained in the crosslinking solution and the complementary amount to improve the durability of the polarizer, as described above .

<Polarizer>

The present invention also provides a polarizing plate having a protective layer on at least one side of a polarizer manufactured by the above method.

The protective layer provided on at least one surface of the polarizer functions to protect the polarizer, and may be, for example, a film protective film or a resin coating layer in the form of a coating layer.

The type of the protective film is not particularly limited as long as it is a film excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc. Specific examples thereof include polyester type such as polyethylene terephthalate, polyethylene isophthalate and polybutylene terephthalate Suzy; Cellulose-based resins such as diacetylcellulose and triacetylcellulose; Polycarbonate resin; Polyacrylic resins such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene resins such as polystyrene and acrylonitrile-styrene copolymer; Polyolefin resins such as polyethylene, polypropylene, cycloolefins or norbornene structures, polyolefins and ethylene propylene copolymers; Polyamide resins such as nylon and aromatic polyamide; Imide resin; Polyether sulfone type resin; Sulfone based resin; Polyether ketone resin: a polyphenylene sulfide resin; Vinyl alcohol-based resin; Vinylidene chloride resins; Vinyl butyral resin; Allylate series resin; Polyoxymethylene type resin; Epoxy resin, and the like, and a film composed of the blend of the thermoplastic resin may also be used. Further, a film made of a thermosetting resin such as (meth) acrylic, urethane, epoxy, or silicone or a film made of an ultraviolet curable resin may be used. Among them, a cellulose-based film having a surface saponified (saponified) by alkali or the like is preferable in consideration of polarization characteristics or durability. Further, the protective film may have the function of the optical layer described below.

Further, the resin coating layer may be a layer formed by curing the curable resin composition coated on at least one surface of the polarizer.

The curable resin composition is preferably an active energy ray curable resin composition, which may include an acrylate-based compound and a photo-radical initiator.

Acrylate compound is a polymerizable substance which can be polymerized by irradiation with an active energy ray (for example, ultraviolet rays, visible light, electron beam, X-ray or the like), and a (meth) acrylate compound having at least one (meth) acryloyloxy group in the molecular structure, Acrylic compound.

(Meth) acryloyloxy group having at least one (meth) acryloyloxy group in the molecule may be a (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule, at least two (meth) (Meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having an acryloyloxy group.

In the present specification, (meth) acryloyloxy group means acryloyloxy group and methacryloyloxy group, and (meth) acrylic compound means acrylate ester derivative and methacrylate ester derivative, and (meth) acrylate monomer Quot; means an acrylate monomer and a methacrylate monomer, and the (meth) acrylate oligomer means an acrylate oligomer or a methacrylate oligomer, respectively.

(Meth) acrylate monomers include monofunctional (meth) acrylate monomers having one (meth) acryloyloxy group in the molecule, difunctional (meth) acrylate monomers having two (meth) acryloyloxy groups in the molecule (Meth) acryloyloxy monomer having at least three (meth) acryloyloxy groups in the molecule. These (meth) acrylate monomers may be used alone or in combination of two or more.

More specific examples of monofunctional (meth) acrylate monomers include tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) Hydroxypropyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-hydroxybutyl (Meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, benzyl (meth) acrylate, isobonyl Acrylate dicyclopentenyloxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, trimethylolpropane (meth) acrylate, pentaerythritol (meth) acrylate, phenoxypolyethyl (Meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethylhexahydrophthalic acid, carboxyethyl (meth) acrylate as the (meth) acrylate monomer containing a carboxyl group, (Meth) acryloyloxyethyl succinic acid, N- (meth) acryloyloxy-N ', N'-dicarboxy-p-phenylenediamine, 4- (meth) And mellitic acid. The monofunctional (meth) acrylate monomer also includes a (meth) acryloylamino group-containing monomer such as 4- (meth) acryloylamino-1-carboxymethylpiperidine.

Examples of bifunctional (meth) acrylate monomers include alkylene glycol di (meth) acrylates, polyoxyalkylene glycol di (meth) acrylates, halogen-substituted alkylene glycol di (meth) Di (meth) acrylates of aliphatic polyols, di (meth) acrylates of hydrogenated dicyclopentadiene or tricyclodecanedialcohol, di (meth) acrylates of dioxane glycol or dioxanedialanol, bis Di (meth) acrylates of alkylene oxide adducts of bisphenol F or bisphenol A, and epoxy di (meth) acrylates of bisphenol F can be used.

More specific examples of the bifunctional (meth) acrylate monomer include ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) (Meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol di (meth) acrylate, 1,6-hexanediol di Acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, diethylene glycol di Acrylate, poly (meth) acrylate, poly (ethylene glycol) di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (Meth) acrylate, 2,2-bis [4- (meth) acryloyloxyethoxyethoxyphenyl] propane, 2,2- (Meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, 1,3-dioxane-2,5-diyl (meth) acrylate, Di (meth) acrylate (trade name: DIOXAN LIKOR), acetal compound of hydroxypivalic aldehyde and trimethylol propane (chemical name: 2- (2-hydroxy-1,1-dimethylethyl) Di (meth) acrylate of 1,3,5-tris (hydroxymethyl-1,3-dioxane) and di (meth) acrylate of 1,3,5-tris (2-hydroxyethyl) isocyanurate.

Examples of polyfunctional (meth) acrylate monomers include glycerin tri (meth) acrylate, trimethylol propane tri (meth) acrylate, ditrimethylol propane tri (meth) acrylate, ditrimethylol propane tetra (meth) Acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol tetra (Meth) acrylates of tri- or higher aliphatic polyols such as trimethylolpropane tri (meth) acrylate and the like. In addition, poly (meth) acrylates of tri- or higher halogen substituted polyols, tri (meth) acrylates of alkylene oxide adducts of glycerin, Acrylate, tri (meth) acrylate of an alkylene oxide adduct of trimethylolpropane, 1,1,1-tris [(meth) Ethoxy in the roil oxy ethoxy] propane, 1,3,5-tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, silicone hexa (meth) acrylate of the isocyanurate.

Photo radical initiators are used for curing acrylate compounds.

The photo-radical initiator that can be used is not particularly limited in the present invention, and any photo-initiator that can initiate photo-curing by irradiation of a known active energy ray can be used. The active energy ray includes visible rays, ultraviolet rays, X rays, electron rays, and the like.

Examples of photoradical initiators include acetophenone, 3-methylacetophenone, benzyldimethylketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan- An acetophenone-based initiator including 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzophenone, 4- Benzoin ether initiators including benzoin propyl ether, benzoin ethyl ether, thiophene-based initiators including 4-isopropylthioxanthone, benzophenone-based initiators including 4,4'-diaminobenzophenone, Quinone, benzaldehyde, anthraquinone, and the like, but the present invention is not limited thereto.

The above-mentioned active energy ray-curable resin composition comprising an acrylate compound and a photo radical initiator may further include other compositions.

If necessary, the active energy-curable resin composition of the present invention may further comprise an epoxy compound, a cationic polymerization initiator, and an oxetane compound.

The epoxy compound is used for increasing the adhesion and adhesion of the cured film, and preferably a hydrogenated epoxy compound, an alicyclic epoxy compound, an aliphatic epoxy compound, or a mixture thereof.

The hydrogenated epoxy compound means a resin obtained by selectively hydrogenating an aromatic epoxy resin under a pressure in the presence of a catalyst. Examples of the aromatic epoxy resin include bisphenol-type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; Novolak type epoxy resins such as phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; A glycidyl ether of tetrahydroxyphenylmethane, a glycidyl ether of tetrahydroxybenzophenone, and an epoxy-modified polyvinyl phenol. Although the hydrogenated epoxy resin of the aromatic epoxy resin becomes a hydrogenated epoxy resin, it is preferable to use hydrogenated bisphenol A glycidyl ether.

The alicyclic epoxy compound means an alicyclic cyclic compound containing at least one epoxy group in the molecule. Specific examples of the alicyclic epoxy compound include an esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid with (7-oxabicyclo [4.1.0] hept- , Ester of 4-methyl-7-oxabicyclo [4.1.0] heptane-3-carboxylic acid with (4-methyl-7-oxabicyclo [4.1.0] hept- -Oxabicyclo [4.1.0] heptane-3-carboxylic acid with 1,2-ethanediol, an ester of (7-oxabicyclo [4.1.0] hepto-3-yl) methanol with adipic acid Esters, esters of (4-methyl-7-oxabicyclo [4.1.0] hept-3-yl) methanol with adipic acid, (7-oxabicyclo [4.1.0] hepto- Ethers of methanol and 1,2-ethanediol, and the like.

The alicyclic epoxy compound may be an alicyclic diepoxycarboxylate. Examples of the alicyclic diepoxycarboxylate include 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxycyclohexylmethyl) adipate, bis 3,4-epoxy-6-methylcyclohexyl) methyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3 ', 4'- Epoxycyclohexanecarboxylate, lactone-modified 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, trimethylcaprolactone modified 3,4-epoxycyclohexylmethyl-3' ? -methyl-? -valerolactone-modified 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, methylenebis (3,4- (3,4-epoxycyclohexylmethyl) ether of ethylene glycol, ethylenebis (3,4-epoxycyclohexanecarboxylate), dioctylcyclohexahydrophthalate, epoxycyclohexahydrophthalic acid di Ethylhexyl and the like.

Examples of the aliphatic epoxy compound include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Specific examples thereof include diglycidyl ether of 1,4-butanediol, diglycidyl ether of 1,6-hexanediol, triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, di (Ethylene oxide, propylene oxide, etc.) to an aliphatic polyhydric alcohol such as glycidyl ether, diglycidyl ether of propylene glycol, ethylene glycol, propylene glycol or glycerin, And polyglycidyl ether of polyether polyol.

The hydrogenated epoxy compound, alicyclic epoxy compound and aliphatic epoxy compound may be used alone or in admixture of two or more.

The cationic polymerization initiator is used for curing the above epoxy compound, and initiates the polymerization reaction of the epoxy compound with a compound that produces a cation or a Lewis acid by irradiation with an active energy ray or heating.

The cationic polymerization initiator that can be used is not particularly limited in the present invention, and representative examples thereof include onium salts such as aromatic diazonium salts, aromatic iodo aluminum salts, and aromatic sulfonium salts, and teth-allene complexes, but are not limited thereto .

Examples of the aromatic diazonium salts include benzene diazonium hexafluoroantimonate, benzene diazonium hexafluorophosphate and benzene diazonium hexafluoroborate.

Examples of aromatic iodoaluminum salts include diphenyl iodonium tetrakis (pentafluorophenyl) borate, diphenyl iodonium hexafluorophosphate, diphenyl iodonium hexafluoroantimonate, di (4-nonylphenyl) ) Iodonium hexafluorophosphate, and the like.

Examples of the aromatic sulfonium salts include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4'-bis [di Bis [di (? - hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate, 4,4 '- bis [diphenylsulfonyl] diphenyl sulfide bishexafluoroantimonate, Bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoro (Pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfone (pentafluorophenyl) borate, (P-tert-butylphenylcarbonyl) -4'-diphenylsulphonio-di Diphenylsulfide tetrakis (pentafluorophenyl) borate, and the like can be used in place of the compound represented by the following general formula (1): &lt; EMI ID = .

Examples of the tetra-allene complexes include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadiene (II) -tris (trifluoromethylsulfonyl) methanide, and the like.

These cationic polymerization initiators may be used singly or in combination of two or more of the above-mentioned compositions. Among them, especially when an aromatic sulfonium salt is used, the curability is excellent and the mechanical properties and adhesive strength of the cured film can be further improved.

The cationic polymerization initiator may be used directly or may be purchased commercially. For example, commercially available products include Kayalad PCI-220, Kayarad PCI-620, UVI-6990 manufactured by Union Carbide, ADEKAOFTMA SP-150, ADEKAOFTMA SP- DPI-102 and DPI-103 manufactured by Midori Kagaku Co., Ltd., CI-5102, CIT-1370, CIT-1682, CIP-1866 S, CIP- , DPI-105, MPI-103, MPI-105, BBI-101, BBI-102, BBI-103, BBI-105, TPS-101, TPS-102, TPS- -105, DTS-102, and DTS-103, and PI-2074 of Rhodia Japan Co., Ltd.

The amount of the cationic polymerization initiator can be limited so that sufficient curing of the epoxy compound is performed and the physical properties of the coating film are not affected. It is preferably used in an amount of 0.01 to 10 parts by weight, more preferably 1 to 6 parts by weight, based on 100 parts by weight of the acrylate-based compound. If the content is less than the above range, the curing of the epoxy compound becomes insufficient, and the mechanical strength and the adhesive strength of the cured film deteriorate. On the other hand, if the content exceeds the above range, The moisture absorbability is increased, and the optical durability performance may be lowered. Therefore, it can be appropriately adjusted within the above range.

The oxetane compound lowers the viscosity of the active energy ray-curable resin composition, thereby facilitating the film production process as well as increasing the curing rate and improving the optical performance by suppressing the yellowing of the finally obtained cured film.

The oxetane compound is preferably used when an epoxy compound is applied to the active energy ray-curable resin composition, and a compound having at least one oxetane ring (quaternary ring ether) in the molecular structure may be used.

The oxetane compound which can be used is not particularly limited in the present invention, and examples thereof include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl ] Benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di (3-ethyl-3-oxetanyl) methyl] Phenol novolak oxetane, and the like.

These oxetane compounds can be used either directly or by purchasing commercially available materials. For example, oxetane compounds such as Aronoxetane OXT-101, Aronoxetane OXT-121, Aronoxetane OXT-211, Cetane OXT-221, and alon oxetane OXT-212.

The content of the oxetane compound can be controlled in order to maximize the effect of improving the adhesion, viscosity and optical performance. For example, the content of the oxetane compound is 10 to 50 parts by weight, preferably 20 to 40 parts by weight, Can be used in parts by weight. If the content is less than the above range, the viscosity of the oxetane compound is lowered or the effect of improving the optical performance is not sufficient. On the other hand, if the content exceeds the above range, the adhesion to the polarizer may be deteriorated , It is preferable to use them appropriately within the above range.

In addition to the above-mentioned components, the curable resin composition according to the present invention may further contain additives such as an antioxidant, a leveling agent, a surface lubricant, a dye, a pigment, an antioxidant, and the like in order to control the adhesive strength, cohesion, viscosity, An antifoaming agent, a filler, a light stabilizer, and the like.

The method for producing the curable resin composition is not particularly limited in the present invention and can be produced by a known method.

The structure of the polarizing plate according to the present invention is not particularly limited, and various kinds of optical layers capable of satisfying required optical characteristics may be laminated on a polarizer or a polarizing plate. For example, a structure in which a protective layer for protecting a polarizer is laminated on at least one surface of a polarizer; A structure in which a surface treatment layer such as a hard coating layer, an antireflection layer, an anti-adhesion layer, a diffusion prevention layer, and an anti-glare layer is laminated on at least one surface of a polarizer or a protective layer; Or a structure in which an alignment liquid crystal layer or another functional film is laminated on at least one surface of the polarizer or on the protective layer to compensate for the viewing angle. Further, it is also possible to use an optical film such as a polarizing conversion device used for forming various image display devices, a retardation film including a reflector, a half-transparent plate, a half-wave plate or a quarter- A plate, a viewing angle compensating film, and a luminance improving film may be laminated with an optical layer. More specifically, a polarizing plate having a structure in which a protective layer is laminated on one surface of a polarizer, includes: a reflective polarizing plate or a transflective polarizing plate in which a reflector or a transflective reflector is laminated on a laminated protective layer; An elliptic or circular polarizer in which a retarder is stacked; A wide viewing angle polarizer in which a viewing angle compensation layer or a viewing angle compensation film is laminated; Or a polarizing plate in which a brightness enhancement film is laminated.

Such a polarizing plate is applicable not only to a general liquid crystal display but also to various image display devices such as an electroluminescent display device, a plasma display device, and a field emission display device.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Examples and Comparative Examples

(1) Example 1

A transparent unoriented polyvinyl alcohol film (PE60, KURARAY Co.) having a degree of saponification of 99.9% or more was immersed in water (deionized water) at 25 ° C for 1 minute and 20 seconds to swell, and then 1 mM / L of iodine and 1% And 0.3% by weight of boric acid was dipped in an aqueous solution for dyeing at 30 DEG C for 2 minutes and 30 seconds. At this time, stretching was performed at a stretching ratio of 1.56 times and 1.64 times at the swelling and dyeing steps, respectively, and the stretching ratio was increased to 2.56 times at the dyeing bath. Subsequently, the resultant was immersed in a crosslinking aqueous solution at 56 ° C. containing 26% by weight of potassium iodide, 13% by weight of boric acid, 3% by weight of boric acid and 0.5% Lt; / RTI &gt; (Second crosslinking step) for 20 seconds in an aqueous solution for crosslinking at 56 ° C containing 13.9% by weight of potassium iodide, 3% by weight of boric acid and 0.5% by weight of zinc nitrate, and the resultant mixture was subjected to crosslinking at a draw ratio of 1.34 Lt; / RTI &gt; Then, it was stretched by 1.01 times while immersing for 10 seconds in a complementary color aqueous solution of 40 ° C containing 5% by weight of potassium iodide, 2% by weight of boric acid and 0.5% by weight of zinc refined chromium nitrate.

At this time, the total cumulative stretching ratio of the swelling, dyeing, crosslinking and complementary phases was set to be six times. After the crosslinking was completed, the polyvinyl alcohol film was dried in an oven at 70 DEG C for 4 minutes to prepare a polarizer.

A triacetylcellulose (TAC) film was laminated on both sides of the prepared polarizer to prepare a polarizing plate.

(2) Examples 2 to 8 and Comparative Examples 1 to 5

A polarizing plate was prepared in the same manner as in Example 1 except for the composition (kind and concentration) of the crosslinked liquid or the metal salt of the complementary liquid described in the following Table 1, the total cumulative stretching ratio, and the metal salt content relative to the total weight of the polarizer.

division Crosslinking solution Complementary liquid gun
accumulate
Stretching cost Polarizer Gun
Weight
Metal salt
content
(weight%) Metal salt Boric acid
(weight%) Temperature
(° C) Metal salt Boric acid
(weight%) Temperature
(° C) Kinds weight% Kinds weight% Example 1 nitric acid
zinc 0.5 3 56 nitric acid
zinc 0.5 3 56 6 0.11 Example 2 nitric acid
zinc One 3 56 nitric acid
zinc One 3 56 6 0.19 Example 3 nitric acid
zinc 3 3 56 nitric acid
zinc 3 3 56 6 0.49 Example 4 nitric acid
zinc 4 3 56 nitric acid
zinc 4 3 56 6 0.83 Example 5 nitric acid
zinc 5 3 56 nitric acid
zinc 5 3 56 6 1.21 Example 6 nitric acid
zinc 0.25 3 56 nitric acid
zinc 0.25 3 56 6 0.06 Example 7 Acetic acid
zinc 3 3 56 Acetic acid
zinc 3 3 56 6 0.54 Example 8 nitric acid
Copper 3 3 56 nitric acid
Copper 3 3 56 6 0.39 Comparative Example 1 - - 3 56 - - 3 56 6 - Comparative Example 2 - - 3 56 nitric acid
zinc 3 3 56 6 0.15 Comparative Example 3 nitric acid
zinc 3 3 56 - - 3 56 6.7 0.29 Comparative Example 4 nitric acid
zinc 3 1.5 53 nitric acid
zinc 3 1.5 40 5.6 0.49

Analysis example

The distances between the crystals and the crystals in the PVA of the polarizers prepared in the above Examples and Comparative Examples were measured by the following methods.

(1) the distance between crystals and crystals in PVA (Long Period)

Synchrotron Beam of PAL Accelerator Laboratory (PAL) was used as equipment and the distance from the sample to the detector at the X-ray wavelength of 1.567 Ohm Strong was 3.0 m. Were measured.

The distance between the crystals in the film for polarizer formation in the stretching direction and the crystal in the staining step of the polarizer produced in the above Examples and Comparative Examples was 27 nm.

Test Example

The physical properties of the polarizers prepared in the above Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 2 below.

1. Optical characteristics (polarization degree, transmittance, A700, A480)

The prepared polarizer was cut into a size of 4 cm x 4 cm, and then the transmittance was measured using an ultraviolet ray spectrophotometer (V-7100, manufactured by JASCO). At this time, the polarization degree is defined by the following equation (4). Note that it is important to note that the degree of polarization of 0.001 also greatly affects the contrast ratio. When the degree of polarization is less than 99.990, the contrast ratio is lowered, and it becomes difficult to realize real black.

&Quot; (4) &quot;

The degree of polarization (P) = [(T ₁ - T ₂ ) / (T ₁ + T ₂ )] ^1/2

(Wherein T ₁ is the parallel transmittance obtained when the pair of polarizers are arranged in parallel with the absorption axis, and T ₂ is the orthogonal transmittance obtained when the pair of polarizers are arranged so that the absorption axes are perpendicular to each other)

&Quot; (2) &quot;

A ₇₀₀ = - Log ₁₀ {(T _{MD, 700} T _{TD, 700} ) / 10000}

(Wherein T _{MD, 700} is a parallel transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes, and T _{TD, 700} represents a state in which a pair of polarizers is perpendicular to the absorption axis Lt; RTI ID = 0.0 &gt; 700nm &lt; / RTI &gt; wavelength)

&Quot; (3) &quot;

A480 = - Log ₁₀ {(T _{MD, 480} * T _{TD, 480} ) / 10000}

(Where T _{MD, 480} is a parallel transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged in parallel with the absorption axes, and T _{TD, 480} represents a pair of polarizers in a state where the absorption axes are orthogonal Which is the orthogonal transmittance at the wavelength of 480 nm obtained when it is placed.

Higher absorbance values for A700 and A480 indicate higher PVA-I ₅ and PVA-I ₃ complexes and a higher degree of polarization.

2. Evaluation of heat resistance

The spectral transmittance? (?) Before and after leaving the polarizing plate prepared in Examples and Comparative Examples at 105 占 폚 for 30 minutes was measured with a spectrophotometer (V7100, manufactured by Nippon Bunko K.K.), and the orthogonal spectral transmittance spectrum was obtained therefrom. A700 represented by the following formula (5) was obtained.

&Quot; (5) &quot;

After heating, A700 = - Log ₁₀ {(T _{MD, 700} T _{TD, 700} ) / 10000}

(Wherein T _{MD, 700} is a parallel transmittance at a wavelength of 700 nm obtained when a pair of polarizing plates are arranged in parallel with the absorption axes, and T _{TD, 700} indicates a state in which the pair of polarizers is orthogonal to the absorption axis Lt; / RTI &gt; at a wavelength of 700 nm).

An orthogonal color b may be defective if it deviates from ± 0.3 based on -0.4.

After the heat resistance evaluation, the presence or absence of the rusting of the polarizing plate was confirmed by visual observation.

And a heat-resistant after A700 the rusty phenomenon upon visual observation on a polarizing plate is not more than 2.3 can be observed, which means that a decrease in PVA-I complex content of the region _5, which absorbs light above 700nm.

division Polarization degree
(%) A700 A480 A700 / A480 Orthogonal color b Heat After A700 Rusty
Occur
Whether (PVA-I ₅
Absorbance) (PVA-I ₃
Absorbance) (PVA-I ₅
Absorbance) Example 1 99.992 3.23 4.43 0.73 -0.4 2.6 X Example 2 99.994 3.66 4.45 0.82 -0.4 2.5 X Example 3 99.995 3.88 4.52 0.86 -0.5 2.7 X Example 4 99.996 4.21 4.46 0.94 -0.7 2.8 X Example 5 99.991 2.98 3.33 0.89 -0.1 4.4 X Example 6 99.990 3.21 3.99 0.80 -0.6 2.3 X Example 7 99.993 3.78 4.44 0.85 -0.6 2.5 X Example 8 99.992 3.55 4.33 0.82 -0.7 2.3 X Comparative Example 1 99.988 4.64 4.33 1.07 -1.4 1.7 ○ Comparative Example 2 99.991 3.02 4.43 0.68 -0.2 2.0 ○ Comparative Example 3 99.990 3.70 2.88 1.28 -1.8 2.1 ○ Comparative Example 4 99.971 3.88 2.45 1.58 -3.1 2.7 X

Table 2 shows that the examples satisfying the formula (1) of the present invention exhibited excellent optical characteristics, showed high absorbance even after the heat resistance test, and did not cause any side effect.

However, in the case of Comparative Examples 1 to 4, which do not satisfy the formula (1) of the present invention, the optical characteristics are lowered and a reddish phenomenon occurs due to the heat resistance test. It was confirmed that the orthogonal color b value was remarkably decreased and the defect occurred.

Claims (17)

Satisfying the following formula (1): &lt; EMI ID =
[Equation 1]
0.7? A700 / A480? 1.0
(In the formula, A700 is defined by the following formula (2)
&Quot; (2) &quot;
A ₇₀₀ = - Log ₁₀ {(T _{MD, 700} T _{TD, 700} ) / 10000}
T _{MD, 700} is a parallel transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,
T _{TD, 700} is the orthogonal transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged so that their absorption axes are perpendicular to each other,
A480 is defined by the following equation (3)
&Quot; (3) &quot;
A480 = - Log ₁₀ {(T _{MD, 480} * T _{TD, 480} ) / 10000}
T _{MD, 480} is a parallel transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,
T _{TD, 480} is the orthogonal transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged so that their absorption axes are orthogonal).
The polarizer of claim 1, wherein the polarizer comprises a metal salt.
The polarizer according to claim 2, wherein the metal salt is at least one selected from the group consisting of zinc nitrate, copper nitrate, aluminum nitrate, magnesium nitrate, and zinc acetate.
The polarizer according to claim 2, wherein the metal salt is contained in an amount of 0.1 to 1% by weight based on the total weight of the polarizer.
A polarizing plate having a protective layer on at least one surface of the polarizer of any one of claims 1 to 4.
The polarizing plate according to claim 5, wherein the protective layer is a protective film or a resin coating layer.
An image display device comprising the polarizing plate of claim 5.
Swelling, dyeing, crosslinking, complementing and stretching the polarizer-forming film;
The distance between the crystals in the polarizer-forming film in the stretching direction in the staining step is 20 to 40 nm;
The dyeing solution comprises a boric acid compound;
Wherein a crosslinking liquid and a complementary liquid containing a metal salt are used in the crosslinking and the complementary coloring step, respectively.
9. The method of claim 8, wherein the stretching direction is the MD direction.
9. The method according to claim 8, wherein the boric acid compound is contained in an amount of 0.3 to 5% by weight based on the total weight of the dyeing solution.
The method of claim 8, And the cumulative stretching ratio until the dyeing step is 2.0 to 3.0 times.
9. The method of producing a polarizer according to claim 8, wherein the boric acid compound concentration in the dyeing step of the dyeing step is lower than the boric acid compound concentration in the cross-linking step.
9. The method of claim 8, wherein the crosslinking step comprises at least a first and a second crosslinking step.
9. The method of claim 8, wherein the metal salt is at least one selected from the group consisting of zinc nitrate, copper nitrate, aluminum nitrate, magnesium nitrate, and zinc acetate.
The method according to claim 8, wherein the metal salt is contained in an amount of 0.5 to 4% by weight based on the total weight of the crosslinking solution.
The method according to claim 8, wherein the metal salt is contained in an amount of 0.5 to 4% by weight based on the total weight of the complementary coloring liquid.
The polarizer according to claim 8, wherein the polarizer produced by the production method satisfies the following formula (1):
[Equation 1]
0.7? A700 / A480? 1.0
(In the formula, A700 is defined by the following formula (2)
&Quot; (2) &quot;
A ₇₀₀ = - Log ₁₀ {(T _{MD, 700} T _{TD, 700} ) / 10000}
T _{MD, 700} is a parallel transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,
T _{TD, 700} is the orthogonal transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged so that their absorption axes are perpendicular to each other,
A480 is defined by the following equation (3)
&Quot; (3) &quot;
A480 = - Log ₁₀ {(T _{MD, 480} * T _{TD, 480} ) / 10000}
T _{MD, 480} is a parallel transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged in parallel with their absorption axes,
T _{TD, 480} is the orthogonal transmittance at a wavelength of 480 nm obtained when a pair of polarizers are arranged so that their absorption axes are orthogonal).