TWI686631B - Polarizer and method for producing the same - Google Patents

Abstract

The present invention provides a polarizer satisfying the following functions: 0.7≦A700/A480≦1.0

A700=-Log₁₀{(T_MD,700×T_TD,700)/10000}

A480=-Log₁₀{T_MD,480×T_TD,480)/10000}

wherein, T_MD,700 and T_TD,700 are transmittances at 700nm wavelength obtained by arranging such that the polarizer while the absorption axis of the polarizer is orthogonal to and parallel to the linear polarization light of the light to be measured, respectively. T_MD,480 and T_TD,480 are transmittances at 480nm wavelength obtained by arranging the polarizer such that the absorption axis of the polarizer is orthogonal to and parallel to the linear polarization light of the light to be measured, respectively. The unitof these transmittances is %.

Description

Polarizer and its manufacturing method

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

Such as used in various image display devices such as liquid crystal display devices (LCD), electric field light emitting (EL) display devices, plasma display devices (PDP), electric field emission display devices (FED), organic light emitting diodes (OLED), etc. The polarizing plate generally contains a polarizer made by absorbing an iodine-based compound or a dichroic polarizing substance in a polyvinyl alcohol (PVA) film, and has a polarizer laminated on one side of the polarizer A polarizer protective film, and a multilayer structure of a polarizer protective film, an adhesive layer bonded to the liquid crystal chip, and a release film are sequentially laminated on the other side of the polarizer.

The polarizer constituting the polarizing plate is suitable for use in an image display device, and in order to provide an image with excellent hue reproducibility, it is required to have both high transmittance and polarization. In addition, as the application of image display devices to various regions expands, and the tendency to increase in size becomes more pronounced, a situation in which various image display devices such as liquid crystal display devices and other image display devices are used at high temperatures for a long period of time has occurred. The improvement of performance and optical performance also increases the demand for durability improvement. As a result, the performance conditions for polarizing plates become very Harsh. Not only that, at present, even image display devices with characteristics suitable for various environments and applications are required, and optical durability including color change under high temperature and high humidity conditions, and high contrast through high alignment and high transmission are required.

In Korean Patent Publication No. 2009-70085, although a method of manufacturing a polarizer is disclosed, no alternative is proposed for the above-mentioned problem points.

[Prior Technical Literature] (Patent Literature)

Patent Literature 1: Korean Patent Publication No. 2009-70085

The object of the present invention is to provide a polarizer with improved color durability and excellent polarization.

In addition, another object of the present invention is to provide a method for manufacturing a polarizer with improved color durability and excellent polarization.

1. A polarizer that satisfies Equation 1 below.

0.7≦A700/A480≦1.0 (1)

In the formula, A700 is defined by the following formula 2: A700=-Log ₁₀ {(T _MD,700 ×T _TD,700 )/10000} (2)

T _MD,700 is to arrange the polarizer such that the absorption axis of the polarizer is orthogonal to the linear polarized light of the measurement light, and the resulting transmittance at a wavelength of 700 nm is obtained. T _TD,700 is to configure the polarizer to When the absorption axis of the polarizer is parallel to the linear polarization of the measurement light, the resulting transmittance at a wavelength of 700 nm, the units of these transmittances are all %, A480 is defined by the following formula 3: A480= -Log ₁₀ {(T _MD,480 ×T _TD,480 )/10000} (3)

T _MD,480 is to arrange the polarizer so that the absorption axis of the polarizer is orthogonal to the linear polarization of the measurement light, and the resulting transmittance at 480 nm wavelength is obtained. T _TD,480 is to arrange the polarizer to When the absorption axis of the polarizer is parallel to the linear polarized light of the measurement light, the resulting transmittance at a wavelength of 480 nm, the units of these transmittances are all %.

2. The polarizer according to the above 1, wherein the polarizer contains a metal salt.

3. The polarizing plate according to the above 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.

4. The polarizer according to the above 2, wherein the metal salt is contained in an amount of 0.05 to 1.5% by weight relative to the total weight of the polarizer.

5. A polarizing plate provided with a protective layer on at least one side of the polarizer according to any one of 1 to 4 above.

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

7. An image display device comprising the polarizing plate described in 5 above.

8. A method of manufacturing a polarizer, comprising: steps of swelling, dyeing, cross-linking, complementary coloring, and extending a film for forming a polarizer; wherein, in the aforementioned dyeing step, the film in the film for forming a polarizer is in the extending direction The distance between the crystals is 20 to 40 nm; the dyeing solution contains a boric acid compound; in the aforementioned cross-linking and complementary color steps, the cross-linking liquid and the complementary color liquid containing metal salts are used, respectively.

9. The method of manufacturing a polarizer according to the above 8, wherein the extending direction is the MD direction.

10. The method for manufacturing a polarizing plate according to the above 8, wherein the boric acid compound is contained in an amount of 0.3 to 5% by weight in the total weight of the dyeing solution.

11. The method for manufacturing a polarizing plate as described in 8 above, wherein the cumulative elongation ratio until the end of the aforementioned dyeing step is 2.0 to 3.0 times.

12. The method for manufacturing a polarizing plate according to the above 8, wherein the cross-linking liquid contains a boric acid compound, and the concentration of the boric acid compound in the dyeing liquid in the dyeing step is lower than that in the cross-linking liquid in the cross-linking step The concentration of boric acid compound.

13. The method of manufacturing a polarizer according to the above 8, wherein the cross-linking step includes at least the first and second cross-linking steps.

14. The method for manufacturing a polarizer according to the above 8, wherein the metal salt is selected from zinc nitrate, copper nitrate, aluminum nitrate, nitric acid At least one of the group consisting of magnesium and zinc acetate.

15. The method for producing a polarizing plate according to the above 8, wherein the total weight of the cross-linking liquid contains 0.5 to 4% by weight of the aforementioned metal salt.

16. The method for manufacturing a polarizing plate according to the above 8, wherein the total weight of the complementary color liquid contains 0.5 to 4% by weight of the aforementioned metal salt.

17. The method for manufacturing a polarizing plate according to the above 8, wherein the polarizing plate manufactured by the foregoing manufacturing method satisfies Equation 1 below.

0.7≦A700/A480≦1.0 (1)

In the formula, A700 is defined by the following formula 2: A700=-Log ₁₀ {(T _MD,700 ×T _TD,700 )/10000} (2)

T _MD,700 is to arrange the polarizer so that the absorption axis of the polarizer is orthogonal to the linear polarization of the measurement light, and the resulting transmittance at a wavelength of 700 nm is obtained. T _TD,700 is to arrange the polarizer to When the absorption axis of the polarizer is parallel to the linear polarization of the measurement light, the resulting transmittance at a wavelength of 700 nm, the units of these transmittances are all %, A480 is defined by the following formula 3: A480 =-Log ₁₀ {(T _MD,480 ×T _TD,480 )/10000} (3)

T _MD,480 is to arrange the polarizer so that the absorption axis of the polarizer is orthogonal to the linear polarization of the measurement light, and the resulting transmittance at 480 nm wavelength is obtained. T _TD,480 is to arrange the polarizer to When the absorption axis of the polarizer is parallel to the linear polarized light of the measurement light, the resulting transmittance at a wavelength of 480 nm, the units of these transmittances are all %.

The polarizer of the present invention can improve the color durability, and even if exposed to high temperature conditions for a long time, the color change can be minimized.

In addition, the polarizer of the present invention has excellent polarization.

In addition, the method of the present invention can produce a polarizer with improved color durability and excellent polarization.

The present invention relates to a polarizer that satisfies Equation 1 to improve color durability and has excellent optical characteristics, and a method of manufacturing the same.

Hereinafter, the present invention will be described in detail.

<polarizer>

The PVA (Polyvinyl Alcohol)-based polarizer contains PVA-I ₅ complex, and the area of PVA-I ₅ complex will shrink under high temperature and high humidity conditions, and PVA-I ₅ complex will become unstable, so The PVA-I ₅ complex is decomposed, and the PVA-I ₅ complex content in the region that absorbs light of 700 nm or more decreases. Therefore, the stability of the dichroic substance complex is reduced and the polarizing plate is discolored (the durability is reduced).

On the other hand, the PVA-based polarizer also contains the PVA-I ₃ complex, and the PVA-I ₃ complex contributes to the display of the degree of polarization.

Based on this, it was judged that the contents of the PVA-I ₅ complex and the PVA-I ₃ complex in the polarizer must be properly maintained.

However, in the manufacture of polarizers, because iodine is added by iodine molecules or iodine salts, it is converted to I according to the specific environment or conditions in the chemical solution tank (dyeing tank, crosslinking tank, and/or complementary color tank) ₃ ^- or I ₅ ^- forms PVA and complexes, so it is difficult to directly control the content (concentration) of I ₃ ^- or I ₅ ^- .

Here, the inventors of the present invention have grasped the relationship between the polarizer A700 and PVA-I ₅ complex content, and A480 and PVA-I ₃ complex content, especially focusing on the ratio between A700 and A480 It becomes an index that can show the content of PVA-I ₅ complex and the content of PVA-I ₃ complex, so that the polarizer can maintain the polarization degree well and will not discolor even under high temperature and high humidity conditions.

The polarizer of the present invention satisfies the following formula 1, and maintains the polarization degree, optical characteristics, and durability very well.

0.7≦A700/A480≦1.0 (1)

In the formula, A700 is defined by the following formula 2, A700=-Log ₁₀ {(T _MD,700 ×T _TD,700 )/10000} (2)

T _MD,700 is to arrange the polarizer so that the absorption axis of the polarizer is orthogonal to the linear polarization of the measurement light, and the resulting transmittance at a wavelength of 700 nm is obtained. T _TD,700 is to arrange the polarizer to When the absorption axis of the aforementioned polarizer is parallel to the linear polarization of the measurement light, the resulting transmittance at a wavelength of 700 nm, the units of which are all %, A480 is defined by the following formula 3: A480=-Log ₁₀ {(T _MD,480 ×T _TD,480 )/10000} (3)

T _MD,480 is to arrange the polarizer so that the absorption axis of the polarizer is orthogonal to the linear polarization of the measurement light, and the resulting transmittance at 480 nm wavelength is obtained. T _TD,480 is to arrange the polarizer to When the absorption axis of the polarizer is parallel to the linear polarized light of the measurement light, the resulting transmittance at a wavelength of 480 nm, the units of all of which are %. That is, T _MD and T _TD are the transmittances when linear polarized light of a specific wavelength is incident on the polarizer in a specific direction.

When the A700/A480 value of the polarizer is less than 0.7, the polarization degree will decrease, and when the value of A700/A480 exceeds 1, the orthogonal hue b will be close to blue and may be defective. A700/A480 can be above 0.73 or above 0.80. A700/A480 can be 0.95 or less, or 0.90 or less.

The polarizer satisfying the above formula 1 can be achieved by various methods. For example, it can be achieved by the following methods: the characteristics of the film for forming a polarizer, the use of a cross-linking liquid containing a metal salt or a complementary color liquid in the manufacture of the polarizer, or adjusting the concentration of the boric acid compound in the cross-linking liquid or the complementary color liquid , Temperature, the concentration of boric acid compound in the dyeing solution or the extension magnification and other methods.

Among them, the case of using a metal salt is specifically described as an example. In the case of using a cross-linking liquid containing a metal salt and a complementary color liquid when manufacturing a polarizer, the metal salt is chemically bonded to the PVA-I ₅ complex The stabilized PVA-I ₅ complex can suppress the occurrence of redness without decomposing the PVA-1 ₅ complex.

The aforementioned metal salt may be used without particular limitation as long as it can chemically bond with the PVA-I ₅ complex to prevent decomposition of the PVA-I ₅ complex. Specific examples include zinc nitrate, copper nitrate, aluminum nitrate, magnesium nitrate, and zinc acetate. Among these, zinc nitrate is preferable in terms of improving durability.

The aforementioned metal salt may contain 0.05 to 1.5% by weight relative to the total weight of the polarizer, and preferably may contain 0.1 to 1% by weight. Within the above range, the color durability and optical characteristics of the polarizer can be maintained well.

<Manufacturing method of polarizer>

Furthermore, the present invention provides a method of manufacturing a polarizer by the above-mentioned present invention.

The method of manufacturing a polarizer by the present invention includes the steps of swelling, dyeing, crosslinking, complementary coloring, and stretching of the polarizer forming film, wherein, when the aforementioned dyeing step is terminated, the polarizer is formed in the extending direction The distance between the crystals in the film is 20 to 40 nm. The dyeing solution contains a boric acid compound. In the aforementioned cross-linking and complementary color steps, a cross-linking liquid containing a metal salt and a complementary color liquid are used, respectively, thereby making it possible to produce even long-term exposure to high temperature conditions Polarizer that still minimizes color changes.

Generally, in the manufacturing process of polarizers, although iodine and iodine salts are added to the dyeing solution during the dyeing process, at this time, when the manufacturing method is carried out by increasing the transmittance, there may be a problem that the polarization degree cannot be solved. In the manufacturing process of polarizers, when the crosslinking solution contains a boric acid compound in the crosslinking process, there will be a problem that the stability of the dichromatic substance complex is reduced, the hue of the polarizer is changed, or the durability is reduced point.

However, in the manufacturing method of the polarizer of the present invention, at the end of the dyeing step, the distance between the crystals in the film (polymer) for forming the polarizer in the extending direction is set to 20 to 40 nm, and the dyeing solution contains boric acid In the case of a compound, the retention time of the boric acid compound is increased before the crosslinking reaction is carried out, and the formation rate of the iodine complex of the dichroic substance is increased in the polarizing film forming film, thereby improving the initial polarization degree. When the distance between the crystals deviates from the above range or the dyeing solution does not contain a boric acid compound, problems such as discoloration of the polarizer, a decrease in durability, and a decrease in the initial polarization degree may occur.

In addition, the method of manufacturing a polarizer of the present invention uses a cross-linking liquid containing a metal salt and a complementary color liquid in the cross-linking and complementary color steps to chemically combine and stabilize the metal salt and the dichromatic substance complex The dichromatic substance complex, therefore, will not decompose the dichromatic substance complex, and suppress the occurrence of reddening.

Therefore, according to the manufacturing method of the polarizer of the present invention, it is possible to manufacture a polarizer that minimizes the color change even if it is exposed to high temperature for a long time.

Hereinafter, a specific example of the method for manufacturing the polarizer of the present invention will be described in more detail. The following specific examples of the manufacturing method of the present invention have the function of understanding the technical idea of the present invention in the same way as the above-mentioned summary of the present invention, so the present invention is not limited and explained by the items described in the following specific examples.

The number of repetitions, step conditions, and the like of the manufacturing steps of the polarizer of the present invention are not particularly limited as long as they do not deviate from the purpose of the present invention. The stretching step may be performed in an independent step, or may be combined with swelling, dyeing, and cross-linking steps Steps 1 and above are performed simultaneously.

The film for forming a polarizer is not particularly limited as long as it can be dyed with a dichroic substance, that is, iodine or the like. For example, Examples include: polyvinyl alcohol film, partially saponified polyvinyl alcohol film; polyethylene terephthalate film, ethylene-vinyl acetate copolymer film, ethylene-vinyl ester alcohol copolymer film, cellulose film, etc. Hydrophilic polymer films such as partially saponified films; or polyene oriented films such as dehydrated polyvinyl alcohol-based films and dehydrochlorinated polyvinyl alcohol-based films. Among these, from the viewpoint of not only the effect of enhancing the uniformity of the in-plane polarization degree is excellent, but also the dyeing affinity for iodine is also excellent, a polyvinyl alcohol-based film is preferable.

Swelling step

The swelling step is to immerse the unstretched film for polarizer formation in a swelling tank filled with an aqueous solution for swelling before dyeing to remove impurities such as dust or anti-adhesives deposited on the surface of the film for polarizer formation, The step of swelling the polarizing film-forming film to improve the stretching efficiency, and also to suppress the unevenness of dyeing, and to improve the physical properties of the polarizing film.

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

When glycerin is contained, the content is not particularly limited. For example, it may be 5 wt% or less in the total weight of the aqueous solution for swelling.

The temperature of the swelling tank is not particularly limited. For example, it can be 20 to 45°C, preferably 20 to 40°C. When the temperature of the swelling tank is within the above-mentioned range, the subsequent stretching and dyeing efficiency are excellent, and the film expansion due to excessive swelling can be prevented.

The application time of the swelling step (swelling time of the swelling tank) is not particularly limited, and it may be, for example, 180 seconds or less, preferably 90 seconds or less. When the immersion time of the swelling tank is within the above range, swelling can be suppressed from becoming oversaturated, cracking caused by softening of the polarizing film forming film can be prevented, and the adsorption of iodine can be made uniform during the dyeing step, which can increase the degree of polarization.

The swelling step and the stretching step can be performed together. In this case, the stretching ratio can be about 1.1 to 3.5 times, preferably 1.5 to 3.0 times. When the aforementioned stretch ratio is less than 1.1 times, wrinkles will occur, and if it exceeds 3.5 times, the initial optical characteristics will decrease.

In the swelling step, expansion rolls, spiral rolls, crown rolls, cloth guides, bending rods, etc. may also be designed in the bath and/or at the entrance and exit of the bath.

Dyeing steps

The dyeing step is a step of immersing the film for polarizing plate formation in a dyeing tank filled with a dyeing solution containing a dichroic substance such as iodine to adsorb iodine to the film for polarizing plate formation.

When the dyeing step of the present invention is terminated, the distance between the crystals in the polarizing film-forming film (polymer) in the extending direction is set to 20 to 40 nm, preferably 20 to 35 nm, more preferably 20 To 32nm, the dyeing solution contains a boric acid compound, thereby increasing the residence time of the boric acid compound before applying the crosslinking reaction, and increasing the formation of PVA-I ₅ complex and PVA-I ₃ complex in the film for forming polarizer rate. By this, the color durability of the polarizer can be improved, and the degree of polarization can be improved.

In addition, the aforementioned extending direction is preferably the MD direction. MD side The direction refers to the longitudinal direction (vertical direction) of the polarizing film forming film, and is also the conveying direction of the polarizing film forming film in the manufacturing method of the present invention.

At the end of the dyeing step, the distance between the crystals in the film for forming the polarizer in the extending direction can be achieved by adjusting the type or extension ratio of the polarizing protective film, etc., preferably, the cumulative extension at the end of the dyeing step can be used The method is adjusted to the range of 2.0 to 3.0 times.

The type of the boric acid compound is not particularly limited, and examples of the boric acid compound include boric acid, sodium borate, potassium borate, and lithium borate. These can be used individually or in combination of 2 or more types.

Although the concentration of the boric acid compound in the aforementioned dyeing solution is not particularly limited, it may be, for example, 0.3 to 5% by weight, preferably 0.5 to 3% by weight in the total weight of the dyeing solution. When the concentration of the boric acid compound in the dyeing solution is less than 0.3% by weight, the effect of increasing the formation of iodine complexes is reduced, and when it exceeds 5% by weight, the cutting phenomenon occurs due to increased stress.

In addition, the boric acid compound in the dyeing liquid may be contained in such a way that it has a lower concentration than the boric acid compound added to the crosslinking liquid in the subsequent crosslinking step.

The dyeing liquid may further contain water, a water-soluble organic solvent or a mixed solvent of these, 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, and more preferably 1 to 200 mmol/L.

In order to improve the dyeing efficiency, the dyeing solution may further contain iodide as a dissolution aid.

The type of iodide is not particularly limited, and examples thereof include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, and tin iodide. , Titanium iodide, etc., from the viewpoint of high solubility in water, potassium iodide is preferred. These can be used individually or in mixture of 2 or more types.

The content of the aforementioned iodide is not particularly limited, for example, it may be 0.01 to 10% by weight, preferably 0.1 to 5% by weight in the total weight of the dyeing solution.

The temperature of the dyeing tank is not particularly limited. For example, it may be 5 to 42°C, preferably 10 to 35°C.

The time for immersing the film for polarizing plate formation in the dyeing tank is not particularly limited, and may be, for example, 1 to 20 minutes, preferably 2 to 10 minutes.

It is also possible to perform the extension step together with the dyeing step. In this case, the extension ratio may be 1.01 to 2.0 times, preferably 1.1 to 1.8 times.

Moreover, the cumulative extension ratio of the polarizer until the dyeing step including the swelling and extension steps is terminated is preferably 2.0 to 3.0 times. Within the above range, the distance between the crystals caused by the present invention can be displayed, which can solve the problem of poor appearance of the film due to wrinkles or a decrease in initial optical characteristics.

Crosslinking steps

The cross-linking step is to prevent the dyeing properties associated with the physically adsorbed iodine molecules from being reduced by the external environment, and to form the dyed polarizers. The step of immersing the film in the cross-linking solution to fix the adsorbed iodine molecules.

Since the cross-linking liquid used in the cross-linking step of the present invention contains a metal salt, the metal salt and the dichroic substance complex are chemically combined, so the mechanism of the hue change of the polarizer can be suppressed, and the durability can be improved.

The iodine of the dichroic dye is unstable in the cross-linking reaction, and the iodine molecule will be detached due to the hot and humid environment, so a sufficient cross-linking reaction is required.

The cross-linking step of the present invention may be carried out in the first cross-linking step and the second cross-linking step, or the cross-linking liquid used in one or more of the aforementioned cross-linking steps may contain a metal salt.

The aforementioned metal salt can be used without particular limitations as described above, but specific examples include zinc nitrate, copper nitrate, aluminum nitrate, magnesium nitrate, and zinc acetate. To improve durability, zinc nitrate is used as Better.

Although the concentration of the metal salt in the aforementioned cross-linking liquid is not particularly limited, for example, it may be 0.5 to 4% by weight in the total weight of the cross-linking liquid. When the concentration of the metal salt in the cross-linking liquid is less than 0.5% by weight, the effect of suppressing color change will not appear, especially the effect of suppressing reddening will occur, and if it exceeds 4% by weight, a decrease in polarization and poor hue will occur problem.

The crosslinking liquid of the present invention may further contain a boric acid compound. Containing a boric acid compound can improve the cross-linking efficiency and suppress wrinkles in the film during the step, and can form an alignment of the dichroic substance to improve the optical characteristics.

Although the concentration of the boric acid compound in the aforementioned cross-linking liquid is not particularly limited, for example, it may be 1 to 10% by weight in the total weight of the cross-linking liquid. It is preferably 2 to 6% by weight. When the concentration of the boric acid compound in the cross-linking liquid is less than 1% by weight, the cross-linking effect may be reduced and the orientation of the film may be lowered. If it exceeds 10% by weight, excessive cross-linking may cause cutting.

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

The cross-linking liquid of the present invention may contain water used as a solvent and an organic solvent that can be dissolved together with water. In order to prevent the uniformity of the degree of polarization in the polarizer surface and prevent the iodine from being attached, it may be further Contains a small amount of iodide.

The aforementioned iodide may be the same as the iodide used in the dyeing step, and the concentration of the aforementioned iodide is not particularly limited, for example, it may be 0.05 to 15% by weight, preferably 0.5 to 11% by weight. When the concentration of the iodide in the cross-linking tank satisfies the above range, it can prevent the iodide ions absorbed in the dyeing step from detaching from the film, or the iodide ions contained in the cross-linking solution penetrate into the film, thereby inhibiting the penetration rate The change.

Although the temperature of the cross-linking tank is not particularly limited, it may be, for example, 20 to 70°C, preferably 40 to 60°C.

The time for immersing the film for polarizing plate formation in the crosslinking tank is not particularly limited. For example, it may be 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

The extension step may be performed together with the cross-linking step. In this case, the extension ratio of the first cross-linking step may be 1.4 to 3.0 times, preferably 1.5 to 2.5 times. In addition, the extension ratio of the second crosslinking step may be 1.01 to 2.0 times, preferably 1.2 to 1.8 times.

The cumulative extension ratio of the aforementioned first cross-linking step and second cross-linking step may be 1.5 to 5.0 times, preferably 1.7 to 4.5 times. When the cumulative stretching ratio is less than 1.5 times, the effect of increasing the cross-linking efficiency becomes weak. If it exceeds 5.0 times, the film may break due to excessive stretching, which may reduce productivity.

Complementary color steps

The complementary color step is a step of adjusting the hue by immersing the film after the aforementioned cross-linking step in a complementary color liquid containing a metal salt, a boric acid compound and an iodide.

The complementary liquid used in the complementary color step of the present invention contains a metal salt, whereby the metal salt and the dichromatic substance complex are chemically combined to improve the stability of the dichromatic substance complex, thereby suppressing polarized light The color change of the sheet can further improve the durability.

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

Although the concentration of the metal salt in the complementary color liquid is not particularly limited, for example, it may be 0.5 to 4% by weight in the total weight of the complementary color liquid. When the concentration of the metal salt in the color correction solution is less than 0.5% by weight, the effect of suppressing color change will not appear, especially the effect of suppressing reddening will occur, and if it exceeds 4% by weight, the decrease in polarization and the hue will be poor problem.

Furthermore, the complementary color liquid of the present invention may further contain a boric acid compound. The boric acid compound may be the same as the boric acid compound used in the dyeing step.

Although the concentration of the boric acid compound in the aforementioned color correction liquid is not particularly limited, for example, it may be 1 to 10% by weight, preferably 2 to 6% by weight in the total weight of the color correction liquid. When the concentration of the boric acid compound in the color correction solution is less than 1% by weight, the iodine alignment cannot be improved, which will weaken the color change suppression and durability improvement effects. When it exceeds 10% by weight, the film will be stretched due to excessive cross-linking. A large amount of tension will be generated, making it difficult to extend and the film will break.

It is preferable that the concentration of the boric acid compound in the complementary color 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 concentration of the boric acid compound in the cross-linking liquid and the concentration of the boric acid compound in the complementary color liquid may have a ratio of 1:0.4 to 0.8. When the complementary coloring liquid contains a small amount of boric acid compound so that the aforementioned concentration ratio does not reach 1:0.4, the iodine alignment cannot be improved, and the effect of color change suppression and durability improvement becomes weak. When an excessive amount of boric acid compound is contained to make it exceed 1:0.8 At this time, the film will generate a large tension during stretching, making it difficult to stretch and the film will break.

The complementary color liquid of the present invention may contain water used as a solvent and an organic solvent that can be dissolved together with water. In order to uniform the degree of polarization in the plane of the polarizer and prevent the detachment of the attached iodine, it may further contain A small amount of iodide.

The aforementioned iodide may be the same as the user used in the dyeing step and the cross-linking step. The concentration of the aforementioned iodide is not particularly limited. For example, it may be 0.05 to 15% by weight in the total weight of the complementary color solution, preferably 0.5 to 11% by weight. When the concentration of the iodide in the complementary color solution satisfies the above range, in order to try to absorb the unadsorbed iodide ions in the dyeing and cross-linking steps Attached to the film, it can increase the penetration of iodine ions contained in the complementary color solution into the film to adjust the penetration rate.

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

Although the iodide in the cross-linking liquid has the effect of preventing the adsorbed iodide ions from detaching from the film during the dyeing step, but the complementary color liquid also contains a large amount of iodide at a similar level to the cross-linking liquid, it will be exposed to the sun for a long time. When heated at a high temperature, iodine decomposes the complex and reduces the durability of the polarizer.

The concentration ratio is not particularly limited. For example, the concentration of iodide in the cross-linking liquid and the concentration of iodide in the complementary color liquid may have a ratio of 1:0.2 to 0.6. When the complementary color solution contains a small amount of iodide to make the aforementioned concentration ratio less than 1:0.2, the hue adjustment cannot be performed. When the excessive iodide is contained to make it exceed 1:0.6, when exposed to high temperature for a long time, it will Decompose iodine complexes and reduce durability.

The temperature of the complementary color tank is 20 to 70°C, and the immersion time of the polyvinyl alcohol-based film in the complementary color tank is 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

In the complementary color step, by extending the polarizing film-forming film, the alignment of the dichroic substance complex can be improved to improve the stability, whereby the polarizer manufactured by the method of the present invention can be exposed to high temperature for a long time After that, it still minimizes the decomposition of the complex and has excellent color durability.

The above-mentioned stretching can also be performed with an stretching ratio of 1.01 to 1.1 times. When the extension ratio is less than 1.01 times, the alignment of the dichromatic substance complex is changed. The good effect becomes weak, and when it exceeds 1.1 times, the film will break due to excessive extension.

Extended steps

The stretching step can be performed together with at least one of the swelling step, the dyeing step, the cross-linking step, and the complementary color step as described above, or it can be performed in air or inert gas while transferring the film after the aforementioned step, or it can be used It is carried out in a separate extension step of the other extension tank filled with extension liquid filled with extension liquid. Alternatively, the unstretched polyvinyl alcohol-based film may be stretched in air or inert gas before the swelling step, and then the film may be subjected to the steps of swelling, dyeing, cross-linking, complementary coloring, washing with water, and drying.

The extension may be carried out in one step, or may be carried out in two or more steps, but it is preferably carried out in two or more steps. The stretching can also be carried out by a method such as setting the peripheral speed difference of the nip roll. In addition, as in the swelling step, expansion rolls, spiral rolls, crown rolls, cloth guides, bending rods, etc. may be provided in the bath and/or at the entrance and exit of the bath.

The total cumulative extension of the present invention is preferably 4.0 to 7.0 times. In this specification, the "cumulative extension ratio" refers to the value obtained by multiplying the extension ratio of each step.

Washing steps

If necessary, the method for manufacturing the polarizer of the present invention may further include a water washing step after the complementary color is completed.

The water washing step is to immerse the film for forming the polarizing film which has completed the complementary color in the water washing tank filled with the washing liquid, and remove the attached This step focuses on the unnecessary residue of the film for polarizer formation.

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

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

The water washing step may be omitted, or may be performed whenever the aforementioned steps such as the dyeing step, the cross-linking step, the extension step, or the complementary color step are completed. Moreover, it can be repeated more than once, and the number of repetitions is not particularly limited.

Drying step

The drying step is to dry the water-washed polarizer forming film, and the neck-in due to drying further enhances the alignment of the dyed iodine molecules to obtain polarizers with excellent optical characteristics. step.

As the drying method, natural drying, air drying, heating drying, microwave drying, hot air drying and other methods can be used. Recently, microwave treatment that only activates and drys the water in the film is used, usually using hot air Processing and far-infrared processing mainly.

Although the temperature during hot air drying is not particularly limited, in order to prevent the deterioration of the polarizer, it is preferably carried out at a relatively low temperature, for example, 20 to 90°C, preferably 20 to 80°C, and more preferably 20 to 60℃.

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

The polarizer manufactured by the manufacturing method of the present invention exhibits excellent durability and polarization degree, and satisfies the following formula 1.

0.7≦A700/A480≦1.0 (1)

In the formula, A700 is defined by the following formula 2: A700=-Log ₁₀ {(T _MD,700 ×T _TD,700 )/10000} (2)

T _MD,700 is the polarizer whose absorption axis is orthogonal to the linear polarization of the measurement light, and the resulting transmittance at a wavelength of 700 nm is obtained. T _TD,700 is a pair of polarizers The polarizer with orthogonal absorption axis is configured such that when the absorption axis of the polarizer is parallel to the linear polarized light of the measurement light, the resulting transmittance at a wavelength of 700 nm, the units of which are all %, A480 is from The definition in formula 3: A480=-Log ₁₀ {(T _MD,480 ×T _TD,480 )/10000} (3)

T _MD,480 is to arrange the polarizer so that the absorption axis of the polarizer is orthogonal to the linear polarization of the measurement light, and the resulting transmittance at 480 nm wavelength is obtained. T _TD,480 is to arrange the polarizer to When the absorption axis of the aforementioned polarizer is parallel to the linear polarized light of the measurement light, the resulting transmittance at a wavelength of 480 nm, the units of all of which are %.

As described above, when the A700/A480 value of the polarizer is less than 0.7, the polarization degree may decrease, and when the value of A700/A480 exceeds 1, the orthogonal hue b becomes close to blue and becomes defective. Further, as described above, the metal salt contained in the crosslinking liquid and the complementary color liquid chemically bound complexes ₅ PVA-I and PVA-I and ₅ to prevent decomposition of the complexes, the range satisfying the above formula 1, can be Improve the durability of polarizers.

<polarizer>

In addition, the present invention provides a polarizing plate provided with a protective layer on at least one surface of a polarizer manufactured by the above method.

The protective layer provided on at least one side of the polarizer serves to protect the polarizer, and may be, for example, a protective film in the form of a 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 excellent in transparency, mechanical strength, thermal stability, moisture shielding property, isotropy, etc. Specific examples include polyethylene terephthalate, poly Polyester-based resins such as ethylene isophthalate and polybutylene terephthalate; cellulose-based resins such as diethyl acetyl cellulose and triethyl acetyl cellulose; polycarbonate-based resin; poly(A Base) polyacrylic resins such as methyl acrylate and poly(meth)acrylate; styrene resins such as polystyrene and acrylonitrile-styrene copolymers; polyethylene, polypropylene, with ring system or reduced Polyolefin resins such as polyolefins and ethylene-propylene copolymers with olefin structure; polyamide resins such as nylon and aromatic polyamide; amide imide resins; polyether resins; resin resins; polyether ketones Resins; vulcanized polystyrene-based resins; vinyl alcohol-based resins; vinylidene chloride-based resins; vinyl butyral-based resins; arylate-based resins; polyoxymethylene-based resins; epoxy-based resins, etc., composed of thermoplastic resins The film can also be made of a blend of the aforementioned thermoplastic resin Into a film. In addition, a film made of thermosetting resin such as (meth)acrylic system, urethane system, epoxy system, polysiloxane system, or ultraviolet ray-based resin may also be used. Among these, in consideration of polarization characteristics or durability, a cellulose-based film having a surface saponified with alkali or the like is particularly preferred. In addition, the protective film may also have the function of the following optical layer.

In addition, the resin coating layer may be a layer in which a curable resin composition is coated on at least one surface of the polarizer and cured.

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

The acrylate-based compound is a substance that can be polymerized by irradiation with active energy rays (such as ultraviolet rays, visible light, electron beams, X-rays, etc.), and it has at least one (meth)acrylonitrile compound in the molecular structure Oxygen (meth)acrylic compounds.

(Meth)acrylic compounds having more than one (meth)acryloyloxy group in the molecule include: (meth)acrylic acid having more than one (meth)acryloyloxy group in the molecule At least one of (meth)acryloyloxy group-containing compounds such as ester monomers and (meth)acrylic oligomers having two or more (meth)acryloyloxy groups in the molecule.

In this specification, (meth)acryloyloxy means acryloyloxy and methacryloyloxy, and (meth)acrylic compounds means acrylate derivatives and methacrylate derivatives, ( Methacrylate monomer system means acrylate monomer and methacrylate monomer, (meth)acrylate oligomer means acrylate oligomer or methacrylic acid Ester oligomer.

Examples of (meth)acrylate monomers include monofunctional (meth)acrylate monomers having one (meth)acryloyloxy group in the molecule, and two (meth)acryloyloxygen groups in the molecule. It is a bifunctional (meth)acrylate monomer based on a group and a multifunctional (meth)acrylate monomer having at least 3 (meth)acryloyloxy groups in the molecule. One type or two or more types of these (meth)acrylate monomers can be used.

More specific examples of monofunctional (meth)acrylate monomers include tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. Ester, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, isobutyl (meth)acrylate, Third butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, benzyl (meth)acrylate , Isobornyl (meth)acrylate, phenoxyethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, trihydroxy Methylpropane (meth)acrylate, neopentyl alcohol (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, as carboxyl group-containing (meth)acrylate monomers include: 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, carboxyethyl (meth)acrylate, 2-(methyl ) Acryloyloxyethyl succinic acid, N-(meth)acryloyloxy-N',N'-dicarboxyp-phenylene diamine, 4-(meth)acryloyloxyethyl partial benzene Three acids, etc. In addition, the monofunctional (meth)acrylate monomers also include (meth)propane, such as 4-(meth)acryloylamino-1-carboxymethylpiperidine Enylamide monomer.

烷二醇或是二

烷二烷醇的二(甲基)丙烯酸酯類、雙酚A或是雙酚F的環氧烷加成物的二(甲基)丙烯酸酯類、雙酚A或是雙酚F的環氧二(甲基)丙烯酸酯類等。 As examples of bifunctional (meth)acrylate monomers, alkylene glycol di(meth)acrylates, polyoxyalkylene glycol di(meth)acrylates, halogen substitution can be used Alkylene glycol di(meth)acrylates, aliphatic polyol di(meth)acrylates, hydrogenated dicyclopentadiene, or tricyclodecanediokanol di(meth)acrylic acid Ester, two

Alkanediol or di

Alkyl dialkanol di(meth)acrylates, bisphenol A or bisphenol F alkylene oxide adducts di(meth)acrylates, bisphenol A or bisphenol F epoxy Di(meth)acrylates, etc.

烷-2,5-二基二(甲基)丙烯酸酯(商品 名：DIOXAN LIKOR)、羥基新戊醛與三羥甲基丙烷的乙縮醛化合物(化學名：2-(2-羥基-1,1-二甲基乙基)-5-乙基-5-羥基甲基-1,3-二

烷)的二(甲基)丙烯酸酯、1,3,5-參(2-羥基乙基)異氰酸酯的二(甲基)丙烯酸酯等。 As more specific examples of bifunctional (meth)acrylate monomers, in addition to ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanedi Alcohol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate Ester, trimethylolpropane di(meth)acrylate, neopentaerythritol di(meth)acrylate, ditrimethylolpropane di(meth)acrylate, diethylene glycol di(meth) Acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di In addition to (meth)acrylates and polytetramethylene glycol di(meth)acrylates, there may be mentioned: silicon di(meth)acrylates, hydroxypivalate neopentyl glycol di(meth) Group) acrylate, 2,2-bis[4-(meth)acryloyloxyethoxyethoxyphenyl]propane, 2,2-bis[4-(meth)acryloyloxyethoxy Ethoxycyclohexyl]propane, hydrogenated dicyclopentadienyl di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, 1,3-di

Acetal compounds of alkane-2,5-diyl di(meth)acrylate (trade name: DIOXAN LIKOR), hydroxypivalaldehyde and trimethylolpropane (chemical name: 2-(2-hydroxy-1 ,1-dimethylethyl)-5-ethyl-5-hydroxymethyl-1,3-di

Alkane) di(meth)acrylate, 1,3,5-ginseng (2-hydroxyethyl) isocyanate di(meth)acrylate, etc.

Examples of polyfunctional (meth)acrylate monomers include glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and ditrimethylolpropane tri(methyl). ) Acrylate, ditrimethylolpropane tetra(meth)acrylate, neopentaerythritol tri(meth)acrylate, neopentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate Base) acrylate, dipentaerythritol penta (meth) acrylate, di neopentaerythritol hexa (meth) acrylate and other polyvalent (meth) acrylates of aliphatic polyhydric alcohols with a price of 3 or more are representative , Other poly(meth)acrylates of halogen-substituted polyols with more than 3 valences, tri(meth)acrylates of alkylene oxide adducts of glycerin, and alkylene oxide addition of trimethylolpropane Tri(meth)acrylate, 1,1,1-ginseng[(meth)acryloxyethoxyethoxy]propane, 1,3,5-ginseng (2-hydroxyethyl) Isocyanate tri (meth) acrylate, silicon hexa (meth) acrylate, etc.

The photo radical initiator is used to harden the acrylate compound.

The photo-radical initiator that can be used is not particularly limited in the present invention, and anyone who can start photocuring by irradiation with a known active energy ray can be used. At this time, the active energy rays include visible rays, ultraviolet rays, X-rays, electron beams, and the like.

As examples of photo radical initiators, there may be cited: Contains acetophenone, 3-methylacetophenone, benzyl dimethyl acetal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 2- Acetophenone of methyl-1-4-(methylthio)phenyl]-2-morpholinylpropane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one Starter, containing diphenyl ketone, 4-chlorodiphenyl ketone, 4,4'-diaminodiphenyl ketone, diphenyl ketone series initiator, containing benzoin propyl ether, Benzoin ether-based initiator of benzoin ethyl ether; thioxanthone-based initiator containing 4-isopropyl thioxanthone; other xanthones, fluorenone, camphorquinone, benzaldehyde, anthraquinone, etc., but not There is no limit to these.

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

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

Epoxy compounds are used to improve the adhesion and adhesion of the cured film, preferably hydrogenated epoxy compounds, alicyclic epoxy compounds, aliphatic epoxy compounds, or the like Etc. mixture.

Hydrogenated epoxy compounds refer to resins obtained by aromatic epoxy resin selectively undergoing hydrogenation reaction under the presence of a catalyst and under pressure. Examples of the aforementioned aromatic epoxy resins include, for example, bisphenol-type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S. ; Such as phenol novolak epoxy resin, cresol novolak epoxy resin, hydroxybenzaldehyde phenol novolak Novolac-type epoxy resins such as epoxy resins; such as multi-functional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxydiphenyl ketone, epoxidized polyethylene phenol, etc. . Although the nucleus hydride of these aromatic epoxy resins becomes hydrogenated epoxy resins, it is preferable to use hydrogenated glycidyl ether of bisphenol A among them.

The alicyclic epoxy compound means an alicyclic compound containing at least one epoxy group in the molecule. As specific examples of the alicyclic epoxy compound, 7-oxabibicyclo[4.1.0]heptane-3-carboxylic acid and (7-oxabicyclo[4.1.0]hept-3- Group) esters of methanol, 4-methyl-7-oxabicyclo[4.1.0]heptane-3-carboxylic acid and (4-methyl-7-oxabicyclo[4.1.0]hept-3- Group) Ester of methanol, ester of 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid and 1,2-ethylene glycol, (7-oxabicyclo[4.1.0]hept-3 -Yl)ester of methanol and adipic acid, (4-methyl-7-oxabicyclo[4.1.0]hept-3-yl)methanol and adipic acid, (7-oxabicyclo[ 4.1.0] Hept-3-yl) methanol and 1,2-ethylene glycol ether and so on.

烷、雙(3,4-環氧基環己基甲基)己二酸酯、雙((3,4-環氧基-6-甲基環己基)甲基)己二酸酯、3,4-環氧基-6-甲基環己基-3’,4’-環氧基-6’-甲基環己烷羧酸酯、ε-己內酯改質3,4-環氧基己基甲基-3’,4’-環氧基環己烷羧酸酯、三甲基己內酯改質3,4-環氧基環己基甲基-3’,4’-環氧基環己 烷羧酸酯、β-甲基-δ-戊內酯改質3,4-環氧基環己基甲基-3’,4’-環氧基環己烷羧酸酯、亞甲基雙(3,4-環氧基環己烷)、乙二醇的二(3,4-環氧基環己基甲基)醚、伸乙基雙(3,4-環氧基環己烷羧酸酯)、環氧基環六氫鄰苯二甲酸二辛酯、環氧基環六氫鄰苯二甲酸二-2-乙基己酯等。 The alicyclic epoxy compound may also be an alicyclic diepoxy carboxylate. Examples of the alicyclic diepoxy carboxylate include: 3,4-epoxycyclohexylmethyl -3',4'-epoxycyclohexane carboxylate, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexyl-methyl- two

Alkanes, bis(3,4-epoxycyclohexylmethyl) adipate, bis((3,4-epoxy-6-methylcyclohexyl)methyl) adipate, 3,4 -Epoxy-6-methylcyclohexyl-3',4'-epoxy-6'-methylcyclohexane carboxylate, ε-caprolactone modified 3,4-epoxyhexylmethyl -3',4'-epoxycyclohexane carboxylate, trimethylcaprolactone modified 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexane Carboxylate, β-methyl-δ-valerolactone modified 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexane carboxylate, methylene bis(3 , 4-epoxycyclohexane), bis(3,4-epoxycyclohexylmethyl) ether of ethylene glycol, ethyl bis(3,4-epoxycyclohexanecarboxylate) , Epoxy hexahydrophthalate dioctyl ester, epoxy hexahydrophthalate di-2-ethylhexyl ester, etc.

Examples of aliphatic epoxy compounds include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Specific examples include: diglycidyl ether of 1,4-butanediol, diglycidyl ether of 1,6-hexanediol, triglycidyl ether of glycerin, and trimethylolpropane Triglycidyl ethers, diglycidyl ethers of polyethylene glycol, diglycidyl ethers of propylene glycol, one type of addition to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, or glycerin or Polyglycidyl ethers of polyether polyols obtained from two or more kinds of oxyoxanes (ethylene oxide, propylene oxide, etc.).

The aforementioned hydrogenated epoxy-based compound, alicyclic epoxy-based compound, and aliphatic epoxy-based compound may be used alone or in combination of two or more.

The cationic polymerization initiator is used by a user to harden the epoxy compound, and a compound that generates a cation or a Lewis acid by irradiation of active energy rays, heating, or the like starts the polymerization reaction of the epoxy compound.

The cationic polymerization initiators that may be used are not particularly limited in the present invention, and representatively include: onium salts such as aromatic diazonium salts, aromatic aluminum iodide salts, and aromatic manganese salts, iron-aromatic complexes, etc., But it is not limited to this.

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

When exemplifying the aromatic aluminum iodide salt, it may be (pentafluorophenyl) boric acid diphenyl iodonium salt, hexafluorophosphate diphenyl iodonium salt, epifluoride hexafluoroantimonate diphenyl iodonium salt, hexafluorophosphate bis (4-nonylphenyl) onium salt, etc.

Examples of the aromatic arsonium salts include triphenylammonium hexafluorophosphate, triphenylammonium hexafluoroantimonate, triphenylammonium (pentafluorophenyl) borate, 4,4′- Bis[diphenylamyl]diphenylsulfide bishexafluorophosphate, 4,4'-bis[bis(β-hydroxyethoxy)phenylamyl]diphenylsulfide bishexafluoroantimonate Salt, 4,4'-bis[bis(β-hydroxyethoxy)phenyl alkynyl]diphenyl sulfide bishexafluorophosphate, 7-[bis(p-tolyl)amyl]-2-iso Propyl thioxanthone hexafluoroantimonate, 7-[bis(p-tolyl)amyl]-2-isopropyl thioxanthone (pentafluorophenyl) borate, 4-phenylcarbonyl-4 '-Diphenyl alkynyl-diphenyl sulfide hexafluorophosphate, 4-(p-tertiary-butylphenylcarbonyl)-4'-diphenyl alkynyl-diphenyl sulfide hexafluoroantimony Acid salt, 4-(p-tertiary-butylphenylcarbonyl)-4'-bis(p-tolyl)amyl-diphenylsulfide (pentafluorophenyl) borate, etc.

In addition, examples of the iron-aromatic hydrocarbon complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, Xylene-cyclopentadienyl iron (II)-ginseng (trifluoromethylsulfonyl) methanide (methanide), etc.

These cationic polymerization initiators can be used alone or in combination of two or more. Among these, when aromatic samium salt is used in particular, it can have excellent hardenability, The mechanical properties and adhesive strength of the cured film can be further improved.

The aforementioned cationic polymerization initiator can be directly produced and used or purchased from a commercial product. For example, as a commercially available product, KAYARAD PCI-220, KAYARAD PCI-620 manufactured by Nippon Kayaku Co., Ltd., UVI-6990 by Union Carbide, and Adeka Optomer-SP-150 manufactured by ADEKA Corporation, Ameka Optomer SP-170, CI-5102, CIT-1370, CIT-1682, CIP-1866S, CIP-2048S, and CIP-2064S, DPI-101, DPI manufactured by Green Chemical Co., Ltd. -102, DPI-103, DPI-105, MPI-103, MPI-105, BBI-101, BBI-102, BBI-103, BBI-105, TPS-101, TPS-102, TPS-103, TPS-105 , MDS-103, MDS-105, DTS-102, and DTS-103, PI-2074 of RHODIA JAPAN Co., Ltd. etc.

The aforementioned cationic polymerization initiator can sufficiently cure the epoxy compound and limit its content without affecting the physical properties of the coating film. With respect to 100 parts by weight of the acrylate-based compound, preferably 0.01 to 10 parts by weight, more preferably 1 to 6 parts by weight. If the content of the cationic polymerization initiator does not reach the above range, the curing of the epoxy compound will become insufficient, and the problem of a decrease in the mechanical strength and subsequent strength of the cured film will occur. If it exceeds the above range, the entire composition The increase of the ionic substance increases the moisture absorption of the cured film, and the optical durability may be reduced. Therefore, it can be used after being appropriately adjusted within the above range.

The oxetane compound can not only reduce the viscosity of the active energy ray-curable resin composition, but also make the film manufacturing process easier, but In order to increase the curing speed, suppress the yellowing of the finally obtained cured film, and bring the effect of improving the optical performance.

The oxetane compound is preferably used when the epoxy-based compound is applied to the active energy ray-curable resin composition, or may have at least one oxetane ring (4-membered cyclic ether) in the molecular structure ) Compounds.

The oxetane compound that can be used in the present invention is not particularly limited, 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-oxetan Group) methyl] ether, 3-ethyl-3-(2-ethylhexyloxymethyl) oxetane, phenol novolak oxetane, etc.

These oxetane compounds can be directly produced or purchased for use on the market, and examples include ARON OXETANE OXT-101, ARON OXETANE OXT-121, ARON OXETANE OXT-211 , ARON OXETANE OXT-221, ARON OXETANE OXT-212, etc.

In order to improve the adhesion and ensure the maximum effect on viscosity and optical properties, the content of heterocyclobutane compound can be suppressed. For example, relative to 100 parts by weight of epoxy compound, 10 to 50 parts by weight can be used, preferably To use 20 to 40 parts by weight. When the content of the oxetane compound does not reach the above range, the viscosity decreases due to the addition of the oxetane compound, and the effects such as the improvement of optical performance are insufficient. If the content exceeds the above range, the density of the polarizer may be There will be a problem of decline Health, it is preferable to use appropriately within the above range.

In addition to the above-mentioned components, the curable resin composition of the present invention may further contain in order to adjust the adhesive force, cohesive force, viscosity, elastic modulus, glass transition temperature, etc. required in the curable resin composition. Various additives such as antioxidants, leveling agents, surface lubricants, dyes, pigments, defoamers, fillers, light stabilizers, etc.

The production method of the curable resin composition is not particularly limited in the present invention, and can be produced by a conventional method.

The structure of the polarizing plate of the present invention is not particularly limited, and it may be formed by laminating various optical layers that can satisfy the necessary optical characteristics on the polarizing plate or the polarizing plate. For example, it may have a structure in which a protective layer for protecting the polarizer is laminated on at least one side of the polarizer; a hard coating, an anti-reflection layer, and an anti-adhesion layer are laminated on at least one side of the polarizer or on the protective layer, The structure of surface treatment layers such as anti-diffusion layer and anti-glare layer; the constructor that has an alignment liquid crystal layer or other functional film that compensates the viewing angle on at least one side of the polarizer or on the protective layer. In addition, wavelength plates (including lambda plates) are included in optical films such as polarization conversion devices, mirrors, semi-transmissive plates, 1/2-wavelength plates, or 1/4-wavelength plates used for forming various image display devices A structure in which at least one of the retardation plate, the viewing angle compensation film, and the brightness enhancement film is laminated as an optical layer. In more detail, it is preferably a polarizing plate having a structure in which a protective layer is laminated on one side of a polarizer, wherein a reflective polarizing plate having a mirror or a semi-transmissive mirror is laminated on the laminated protective layer Or semi-transmissive polarizing plate; laminated circular or circular polarizing plate with phase difference plate; laminated with viewing angle compensation layer or viewing angle compensation film Polarizer with wide viewing angle; or polarizer with laminated film with brightness enhancement.

Such a polarizing plate can be applied not only to general liquid crystal display devices, but also to various image display devices such as electric field light-emitting display devices, plasma display devices, electric field emission display devices, and the like.

In the following, preferred embodiments are suggested for understanding the present invention, but these embodiments are only to exemplify the inventor, and do not limit the patent application scope of the appendix. Those with ordinary knowledge in the technical field of the subject will clearly understand Various changes and corrections can be applied to the embodiments within the scope of the present invention and the scope of the technical idea. Of course, such changes and corrections also fall within the scope of the additional patent application.

Examples and comparative examples (1) Example 1

After immersing the transparent unstretched polyvinyl alcohol (PVA) film (PE60, KURARAY company) with a saponification degree of 99.9% or more in 25°C water (deionized water) for 1 minute and 20 seconds to swell it, then immerse it in Dyeing was carried out in an aqueous solution for dyeing at 30° C. of 1 mM/L of iodine, 1% by weight of potassium iodide, and 0.3% by weight of boric acid for 2 minutes 30 seconds. At this time, in the swelling and dyeing steps, the stretching ratios are 1.56 times and 1.64 times, respectively, so that the cumulative stretching ratio after passing through the dyeing tank becomes 2.56 times. Next, it was immersed in a 56°C cross-linking aqueous solution containing 13.9% by weight of potassium iodide, 3% by weight of boric acid, and 0.5% by weight of zinc nitrate of Oiichi Gold Co., Ltd. for 26 seconds (the first cross-linking step) and cross-linked. Extend with an extension ratio of 1.7 times. After that, it contains 56% by weight of potassium iodide 13.9% by weight, boric acid 3% by weight, and zinc nitrate 0.5% by weight The aqueous solution for crosslinking at ℃ was immersed in the second crosslinking step for 20 seconds (second crosslinking step) and allowed to crosslink while being stretched at an extension ratio of 1.34 times. Next, it was immersed in a 40° C. aqueous solution containing 40% by weight of potassium iodide, 2% by weight of boric acid, and 0.5% by weight of zinc nitrate of Oiichi Gold Co., Ltd. for 10 seconds, while extending to 1.01 times.

At this time, an attempt was made to increase the total cumulative stretch ratio in the MD direction of the swelling, dyeing, crosslinking, and complementary color steps to 6 times. After the crosslinking was completed, the polyvinyl alcohol film was dried in an oven at 70°C for 4 minutes to manufacture a polarizer.

A polarizing plate is manufactured by stacking triacetyl cellulose (TAC) films on both sides of the manufactured polarizer.

(2) Examples 2 to 8 and Comparative Examples 1 to 3

In addition to the composition (type and concentration), temperature, total cumulative elongation ratio, and metal salt content of the total weight of the polarizer, the cross-linking liquid or the complementary color metal salt described in Tables 1 and 2 below, the rest The polarizing plate was manufactured in the same manner as in Example 1.

Analysis example

The distance between crystals in the PVA of the polarizer manufactured in the above examples and comparative examples was measured by the following method.

(1) Distance between crystals in PVA (Long Period)

Using the Synchrotron Beam of the Accelerator Research Institute (PAL), the distance from the sample to the measuring device was set to 3.0 m at the X-ray wavelength of 1.567 Å. Based on the peak at the scattering vector q, the measurement was taken as Beam path 1 mm The distance between the crystals in the extension direction in the PVA obtained by the cumulative extension ratio up to the time of passing through the dyeing tank.

When the dyeing steps of the polarizers manufactured in the above examples and comparative examples were terminated, the distance between the crystals in the film for forming a polarizer in the extending direction was 27 nm.

Test example

The physical properties of the polarizers manufactured in the above examples and comparative examples were measured by the following methods, and the results are shown in Tables 3 and 4 below.

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

After cutting the manufactured polarizer to a size of 4 cm×4 cm, the transmittance was measured using an ultraviolet-visible light spectrometer (V-7100, manufactured by JASCO). At this time, the degree of polarization is defined by Equation 4 below. Also, it must be noted that even a difference of about 0.001 in the degree of polarization will greatly affect the contrast ratio. When the polarization degree is less than 99.990, the contrast ratio will decrease, making it difficult to realize the realization of real black.

Polarization (P)=[(T ₁ -T ₂ )/(T ₁ +T ₂ )] ^1/2 ×100 (4)

In the formula, T ₁ is the parallel transmittance obtained when a pair of polarizers are arranged parallel to the absorption axis, and T ₂ is the orthogonal cross-section obtained when a pair of polarizers are arranged to be orthogonal to the absorption axis. Penetration rate. The unit of polarization (P) is %.

A700 and A480 are the absorbances defined by Equations 2 and 3 above.

When the absorbance values of A700 and A480 are high, = means that the content of PVA-I ₅ and PVA-I ₃ complex is high and the degree of polarization is high.

2. Heat resistance evaluation

The polarizing plates manufactured in the examples and comparative examples were measured by spectrophotometer (V7100, Nippon Spectroscopy Co., Ltd.) by measuring the spectral transmittance τ(λ) before and after standing at 105° C. for 30 minutes and after being left to stand. Orthogonal spectroscopic transmission spectrum to obtain the A700 defined by the orthogonal hue b and Equation 2 above.

When the orthogonal hue b deviates from ±0.3 on the basis of -0.4, defects will occur.

After evaluating the above heat resistance, it was confirmed by visual observation whether the polarizing plate had reddened.

In the case where A700 after heat resistance is 2.1 or less, redness may sometimes be observed when the polarizing plate is visually observed, which means that the content of the PVA-I ₅ complex compound that absorbs the light region of 700 nm or more is reduced.

The results are shown in Tables 3 and 4. Referring to these tables, Examples satisfying Formula 1 of the present invention show excellent optical characteristics, and also show high absorbance after the heat resistance test, and do not cause redness. In Table 4, X indicates that redness does not occur, and O indicates that redness occurs.

However, Comparative Examples 1 to 3, which did not satisfy Formula 1 of the present invention, it was confirmed that the optical characteristics were degraded, the redness phenomenon occurred after passing the heat resistance test, or the b value of the orthogonal hue was significantly decreased, resulting in defects.

Claims (14)

A polarizer is a polyvinyl alcohol-based polarizer that satisfies the following formula 1, the polyvinyl alcohol-based polarizer contains a metal salt, and contains 0.05 to 1.5% by weight of the foregoing with respect to the total weight of the polyvinyl alcohol-based polarizer Metal salt, 0.7≦A700/A480≦1.0 …(1) In the formula, A700 is defined by the following formula 2: A700=-Log ₁₀ {(T _MD,700 ×T _TD,700 )/10000} …(2 ) T _{MD, 700} sets the polarizer such that the absorption axis of the polarizer is orthogonal to the linear polarization of the measurement light, and the resulting transmittance at a wavelength of 700 nm is obtained. T _{TD, 700} sets the polarizer When the absorption axis of the polarizer is parallel to the linear polarized light of the measurement light, the resulting transmittance at a wavelength of 700 nm, the units of these transmittances are all %, A480 is defined by the following formula 3: A480 =-Log ₁₀ {T _MD,480 ×T _TD,480 )/10000} …(3) T _MD,480 is when the polarizer is arranged such that the absorption axis of the polarizer is orthogonal to the linear polarization of the measurement light , The obtained transmittance at 480nm wavelength, T _{TD, 480} is to arrange the polarizer so that the absorption axis of the polarizer is parallel to the linear polarization of the measurement light, the resulting transmittance at 480nm wavelength, this The unit of equal penetration rate is %. The polarizer as described in item 1 of the patent application, wherein the metal salt is selected from zinc nitrate, copper nitrate, aluminum nitrate, magnesium nitrate and acetic acid At least one species in the group formed by zinc. A polarizing plate is provided with a polarizer as described in item 1 or 2 of the patent application scope, and a protective layer provided on at least one side of the polarizer. The polarizing plate as described in item 3 of the patent application range, wherein the protective layer is a protective film or a resin coating layer. An image display device is provided with the polarizing plate described in item 3 or 4 of the patent application. A method of manufacturing a polarizer, which includes the steps of swelling, dyeing, cross-linking, complementary coloring, and extending a film for forming a polarizer, wherein, at the end of the aforementioned dyeing step, the film in the film for forming a polarizer in the extending direction The distance between the crystals is 20 to 40 nm. The dyeing solution contains a boric acid compound. In the aforementioned crosslinking and complementary color steps, a crosslinking solution containing a metal salt and a complementary coloring solution are used. The concentration of the boric acid compound in the dyeing solution is 0.3% by weight or more And less than 3% by weight. The method of manufacturing a polarizer as described in item 6 of the patent application, wherein the extending direction is the MD direction. The method for manufacturing a polarizing plate as described in item 6 or 7 of the patent application range, wherein the total weight of the dyeing solution contains 0.3 to 5% by weight of the boric acid compound. The method of manufacturing a polarizer as described in item 6 or 7 of the patent application scope, wherein the cumulative elongation ratio until the termination of the aforementioned dyeing step is 2.0 To 3.0 times. The method for manufacturing a polarizer as described in item 6 or 7 of the patent application, wherein the cross-linking step includes at least the first and second cross-linking steps. The method for manufacturing a polarizer according to item 6 or 7 of the patent application, 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 for manufacturing a polarizer as described in item 6 or 7 of the patent application range, wherein the total weight of the cross-linking liquid contains 0.5 to 4% by weight of the aforementioned metal salt. The method of manufacturing a polarizer as described in item 6 or 7 of the patent application range, wherein the total weight of the complementary color liquid contains 0.5 to 4% by weight of the aforementioned metal salt. The method for manufacturing a polarizer according to claim 6 or 7, wherein the polyvinyl alcohol-based polarizer manufactured by the foregoing manufacturing method satisfies the following formula 1, and the polyvinyl alcohol-based polarizer The total weight of the vinyl alcohol polarizer contains 0.05 to 1.5% by weight of metal salt, 0.7≦A700/A480≦1.0… (1) In the formula, A700 is defined by the following formula 2: A700=-Log ₁₀ {( T _MD,700 ×T _TD,700 )/10000}…(2) T _MD,700 is when the polarizer is arranged so that the absorption axis of the polarizer is orthogonal to the linear polarization of the measurement light, the result is 700 nm Transmittance of wavelength, T _TD,700 is to arrange the polarizer so that the absorption axis of the polarizer is parallel to the linear polarized light of the measurement light. The units are all %. The A480 series is defined by the following formula 3: A480=-Log ₁₀ {(T _MD,480 ×T _TD,480 )/10000}…(3) The T _MD,480 series configures the aforementioned polarizer as When the absorption axis of the polarizer is orthogonal to the linear polarization of the measurement light, the resulting transmittance at a wavelength of 480 nm, T _TD,480 is the arrangement of the polarizer so that the absorption axis of the polarizer and the measurement light are straight When the polarized light is in a parallel state, the resulting transmittance at a wavelength of 480 nm, the units of these transmittances are all %.