KR101663698B1 - Preparing method for polarizer - Google Patents

Abstract

More particularly, the present invention relates to a polarizer-forming film comprising a step of swelling, dyeing, stretching, crosslinking, complementing, washing and drying a polarizer-forming film, The present invention relates to a method for producing a polarizer capable of producing a polarizer having a higher orthogonal b value, less staining unevenness, and improved polarization degree by containing a larger amount of I ₃ -containing complex.

Description

PREPARING METHOD FOR POLARIZER [0002]

The present invention relates to a method for producing a polarizer.

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 having such a structure is produced through a complicated process of swelling, dyeing, stretching, crosslinking, washing and drying the PVA film. In the swelling step, the polarizer absorbs water and swells, And a wrinkle in a direction (TD) perpendicular to the traveling direction. The wrinkles generated thereafter cause non-uniformity of the phase difference unevenness and the content of the dichroic substance, resulting in uneven dyeing.

Dyeing unevenness due to such unevenness is further exacerbated when the content of the dichroic substance is decreased in order to increase the transmittance, which is a factor to deteriorate the visibility.

Furthermore, in recent years, as the field of use of liquid crystal display devices has been expanded and peripheral technologies have been advanced, demands for the performance of polarizers have become more stringent. Specifically, there is a demand for a polarizer having high contrast (high transmittance and high polarization degree), less stain, and excellent color.

Korean Patent Laid-Open Publication No. 2009-82197 discloses a polarizer protective film, a polarizing plate, and an image display device, but fails to provide an alternative to the above problem.

Korea Patent Publication No. 2009-82197

An object of the present invention is to provide a method for producing a polarizer which is excellent in color tone and degree of polarization and can reduce staining unevenness.

Another object of the present invention is to provide a method for producing a polarizer having an improved heat resistance and suppressing the occurrence of a reddish phenomenon under a heat-resistant condition and having a low shrinkage force.

1. A method for producing a polarizer, comprising the step of swelling, dyeing, stretching, crosslinking, complementing, washing and drying a film for forming a polarizer, further comprising a pre-heat treatment step between the complementary coloring step and the water washing step.

2. The method of producing a polarizer according to 1 above, wherein the heat treatment is performed so that the polarizer forming film having a unit volume of 5 to 75 cm ³ in the pre-heat treatment step receives a heat quantity of 0.1 Kcal to 500 Kcal.

3. The method of manufacturing a polarizer according to item 1 above, wherein the pre-heat treatment step is performed by irradiating infrared rays to the polarizer-forming film.

4. The method of producing a polarizer according to 3 above, wherein the infrared ray has a wavelength of 1 탆 to 5 탆.

5. The method of producing a polarizer according to item 1 above, wherein the drying step is performed so that the polarizer-forming film having a unit volume of 5 to 75 cm ³ receives a calorie of 0.1 Kcal to 500 Kcal.

6. The method of producing a polarizer according to 5 above, wherein infrared rays having a wavelength of 1 to 5 탆 are irradiated in said drying step.

7. The method of producing a polarizer according to 5 above, wherein the surface temperature of the polarizer-forming film in said drying step is 50 to 100 占 폚.

8. A method for producing polarizer, comprising the step of swelling, dyeing, stretching, crosslinking, complementing, washing and drying the polarizer-forming film, and further comprising a pre-heat treatment step of irradiating the polarizer-forming film with infrared rays between the complementary- and,

Wherein the pre-heat treatment step and the drying step are performed by irradiating infrared rays having a wavelength of 1 to 5 占 퐉 so that the film for forming a polarizer having a unit volume of 5 to 75 cm ³ receives a heat quantity of 0.1 Kcal to 500 Kcal.

The present invention can produce a polarizer having a high biaxis value and high color tone, less staining unevenness, and improved polarization degree by containing a larger amount of I ₃ -containing complex. In this way, the polarizer-forming film can be further washed with water more thoroughly during production, and a polarizer with a small residual foreign matter can be produced.

Further, the present invention can produce a polarizer having a low shrinkage force, which has an improved heat resistance by containing a large amount of I ₅ -containing complexes, thereby suppressing the occurrence of a reddish phenomenon under heat-resistant conditions.

The present invention is a film for a polarizer formed swollen, dyed, stretched, cross-linking, includes a complementary color, water washing and drying steps to, line between the complementary step and washing step-by including a heat treatment step more, than the I ₃ containing complex To a method for producing a polarizer capable of producing a polarizer having a high orthogonal b value, a small staining unevenness, and an improved polarization degree.

Hereinafter, the present invention will be described in more detail.

The method for producing a polarizer of the present invention includes a step of swelling, dyeing, stretching, crosslinking, complementing, washing and drying a film for forming a polarizer, and further includes a pre-heat treatment step between the complementary coloring step and the water washing step. The number of repetitions of each process, the process conditions, and the like are not particularly limited as long as they do not deviate from the object of the present invention. The stretching step may be performed in an independent step, or may be performed simultaneously with at least one of the swelling, staining and crosslinking steps.

Examples of the stretching method include dry stretching, wet stretching, hybrid stretching in which the above two stretching methods are mixed, and the like. Hereinafter, wet stretching and stretching are performed simultaneously in each step as an example, A method for producing the polarizer of the present invention will be described, but the present invention is not limited thereto. Among the above steps, the remaining steps except for the pre-heat treatment and drying step are carried out in a state in which the film for forming a polarizer is immersed in a constant temperature bath.

Polarizer  Forming film

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 preferable 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.

The thickness of the film for forming a polarizer is not particularly limited and may be, for example, 5 to 100 占 퐉, preferably 20 to 80 占 퐉.

<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.

Water (pure water, deionized water) can usually be used as a swelling aqueous solution, and when a small amount of glycerin or potassium iodide is added thereto, the swelling of the polymer film and the processability can be improved.

The content of glycerin and potassium iodide is not particularly limited and may be, for example, 5 wt% or less and 10 wt% or less, respectively, in the total weight of the aqueous swelling solution.

The temperature of the swelling bath is not particularly limited, and may be, for example, from 0 to 60 캜, and preferably from 10 to 50 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.

<Stage of dyeing>

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.

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 dyeing solution used in the dyeing step of the present invention may further comprise a boric acid compound. By including the boric acid compound in the dyeing solution, the retention time of the boric acid compound before the crosslinking reaction can be improved to increase the rate of formation of the dichroic complex in the film for forming a polarizer. Accordingly, the color durability of the polarizer can be improved, and the degree of polarization can be improved.

The concentration of the boric acid compound in the dyeing solution is not particularly limited, but may be, for example, 0.1 to 5% by weight, preferably 0.3 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 0.1% by weight, the effect of increasing iodine complex formation is lowered. If the concentration of boric acid compound is more than 5% by weight, cutting may occur due to stress increase.

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, and preferably boric acid. These may be used alone or in combination of two or more.

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.

The cumulative stretching ratio of the polarizer to the swelling and stretching steps is preferably 1.2 to 4.0 times. If the cumulative stretching ratio is less than 1.2 times, wrinkles may occur in the film. If the cumulative stretching ratio is more than 4.0 times, initial optical characteristics may be lowered.

<Bridging stage>

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.

The crosslinking solution used in the crosslinking step of the present invention includes a boric acid compound. The crosslinking solution contains a boric acid compound to improve the crosslinking efficiency, thereby suppressing the occurrence of wrinkles in the film during the process, and to improve the optical properties by forming an alignment of the dichroic substance.

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 can be carried out in the first crosslinking step and the second crosslinking step, and the boric acid compound can be included in the crosslinking solution used in at least one of the crosslinking steps.

The concentration of the boric acid compound in the crosslinking solution is 1 to 4.5% by weight, preferably 1.5 to 3.8% by weight. When the concentration of the boric acid compound in the crosslinking liquid water is less than 1% by weight, the degree of polarization decreases. When the concentration exceeds 4.5% by weight, the contraction force increases.

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 that is mutually soluble together with water and water used as a solvent and may contain a small amount of potassium iodide in order to prevent the uniformity of the degree of polarization in the plane of polarizers and the desorption of the iodine .

The concentration of potassium iodide in the crosslinking solution is 1 to 15% by weight, preferably 5 to 11% by weight. If the concentration of potassium iodide in the crosslinking solution is less than 1% by weight, the degree of polarization decreases. If the concentration exceeds 15% by weight, the heat resistance is lowered, and a reddish phenomenon may occur upon prolonged exposure at a high temperature.

In addition, the crosslinking solution may further contain the iodide described above to the extent that the object of the present invention is not impaired.

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 step is a step of additionally fixing the insufficient iodine molecules in the crosslinking step.

The complementary liquid used in the complementary step of the present invention includes a boric acid compound. By including the boric acid compound, the complementary liquid can improve the crosslinking efficiency, suppress the occurrence of wrinkles of the film during the process, and improve the optical characteristics by forming the alignment of the dichroic substance.

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 concentration of the boric acid compound in the complementary colorant is 0.5 to 3% by weight, preferably 1 to 2.5% by weight. If the concentration of the boric acid compound in the complementary coloring liquid is less than 0.5% by weight, the degree of polarization decreases. When the concentration of the boric acid compound exceeds 3% by weight, the contraction force increases.

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

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 a small amount of potassium iodide is added in order to prevent the uniformity of the degree of polarization in the plane of the polarizer and the desorption of the dyed iodine .

The concentration of potassium iodide in the complementary liquid is 1 to 15% by weight, preferably 5 to 11% by weight. If the concentration of potassium iodide in the crosslinking solution is less than 1% by weight, the degree of polarization decreases. If the concentration exceeds 15% by weight, the heat resistance is lowered, and a reddish phenomenon may occur upon prolonged exposure at a high temperature.

In addition, the complementary liquid may further include the iodide described above to the extent that the object of the present invention is not impaired.

The temperature of the complementary color bath is not particularly limited, but may be, for example, 20 to 70 ° C, preferably 40 to 60 ° C.

The time for immersing the polarizer-forming film in the sub-color tones 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 performed together with the complementary coloring step. In this case, the stretching ratio of the complementary coloring step may be 1 to 1.15 times, preferably 1.01 to 1.1 times.

The complementary coloring step cumulative stretching ratio may be 1.5 to 7 times, preferably 1.7 to 6 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 7 times, excessive stretching may cause breakage of the film and production efficiency may be reduced.

<Line-heat treatment step>

The pre-heat treatment step is performed between the complementary color step and the water wash step.

The pre-heat treatment step further promotes crosslinking of the additional boric acid (increase in the intramolecular crosslinking of the polymer) to increase the formation of the iodine complex space in the film for forming a polarizer, thereby forming a polymer (for example, polyvinyl alcohol) It is a step that can increase the amount of I ₃ complex. As a result, it is possible to improve the color by improving the orthogonal b value, suppress the uneven dyeing, and improve the degree of polarization. The flushing margin in the flushing step to be described later can be ensured, which will be described later in detail.

The heating method in the line-heat treatment step is not particularly limited, and a known method such as natural drying, heat drying, microwave drying, hot air drying, infrared light and the like can be used. However, , Staining unevenness, degree of polarization, and the like.

The pre-heat treatment step may be performed, for example, so that the polarizer-forming film having a unit volume of 5 to 75 cm ³ receives a calorie of 0.1 Kcal to 500 Kcal. If the calorific value of the unit volume of the polarizer forming film is less than 0.1 Kcal, improvement in the crosslinking of boric acid and improvement in color may be insufficient. If the heating amount exceeds 500 Kcal, yellowing of the polarizer forming film may occur. The amount of heat received by the polarizer-forming film can be controlled by changing the heat treatment temperature, the distance from the heat source, the output, the wavelength of the heat source, and the heat treatment time, but is not limited thereto.

The execution time of the pre-heat treatment step is not particularly limited, and may be, for example, 0.1 minute to 10 minutes, preferably 0.1 minute to 5 minutes, and more preferably 0.1 minute to 1 minute.

When the pre-heat treatment step is performed by irradiating infrared rays, the wavelength of the infrared rays may be 1 to 5 mu m. If the wavelength of the infrared ray is less than 1 탆, the improvement in boric acid crosslinking and the effect of improving color are insignificant. If the wavelength is more than 5 탆, yellowing of the film for forming a polarizer can be caused. More preferably in the range of 1.5 to 3 占 퐉 in terms of boric acid crosslinking improving effect and yellowing inhibition.

<Washing step>

The washing step is a step of immersing the crosslinked and stretched polarizer forming film in a water bath filled with aqueous solution for washing to remove unnecessary residues such as boric acid attached to the polarizing 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, 5 to 60 ° C, preferably 8 to 40 ° C.

When the polarizer-forming film is exposed to water for a long time, the polymer (for example, polyvinyl alcohol) -I ₃ complex can be excessively converted to the polymer-I ₅ complex, Problems can arise. Thus, in the production of a polarizer, water is usually used in a short time in order to reduce the loss of the I ₃ -containing complex, and foreign matter remains on the film for forming a polarizer even after washing.

However, in the case of the method for producing a polarizer of the present invention, the amount of I ₃ -containing complex is increased by the above-described pre-heat treatment, so that the film for forming a polarizer can be washed more sufficiently than in the prior art. Thus, a polarizer having a smaller amount of foreign matter can be produced.

The wash step may be performed each time previous steps such as dyeing step, crosslinking step or stretching 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 simultaneously improving the orientation of the molecules of the iodine molecules so as to improve the optical characteristics and to impart durability.

The heating method in the drying step is not particularly limited and known methods such as natural drying, heat drying, microwave drying, hot air drying, and infrared light can be used, but it can be carried out preferably by irradiating infrared rays under heating.

When infrared rays are irradiated, it is possible to further accelerate the crosslinking of the additional boric acid (increase the intermolecular cross-linking of the polymer), thereby increasing the formation of the iodine complex space in the film for forming a polarizer, Vinyl alcohol) -I ₅ complex amount can be increased. This improves the heat resistance reliability and improves the occurrence of ridges under heat-resistant conditions.

In addition, by maximizing the effect of eliminating the internal stress of the film caused by stretching performed at the time of producing the polarizer, the shrinking force of the polarizer can be lowered and the durability can be increased.

As a preferred embodiment of the present invention, the wavelength of the infrared rays may be 1 to 5 mu m. If the wavelength of the infrared ray is less than 1 탆, the improvement in boric acid crosslinking and the effect of improving color are insignificant. If the wavelength is more than 5 탆, yellowing of the film for forming a polarizer can be caused. More preferably in the range of 1.5 to 3 占 퐉 in terms of boric acid crosslinking improving effect and yellowing inhibition.

The drying step may be performed, for example, so that the film for forming a polarizer having a unit volume of 5 to 75 cm ³ receives a calorie of 0.1 Kcal to 500 Kcal. If the calorific value of the unit volume of the polarizer forming film is less than 0.1 Kcal, improvement in the crosslinking of boric acid and improvement in color may be insufficient. If the heating amount exceeds 500 Kcal, yellowing of the polarizer forming film may occur. The amount of heat received by the polarizer-forming film can be controlled by changing the heat treatment temperature, the distance from the heat source, the output, the wavelength of the heat source, and the heat treatment time, but is not limited thereto.

The treatment temperature in the drying step is not particularly limited, and may be, for example, 60 to 120 ° C. The drying step may be carried out, for example, for 30 seconds to 5 minutes, but is not limited thereto.

The surface temperature of the polarizer-forming film to be dried is preferably a temperature at which the internal stress can be solved to the maximum, for example, 50 to 100 캜. It is possible to prevent deterioration of the film polymer in the above range and to further improve the internal stress reduction effect. If the temperature of the film is less than 50 캜, the effect of resolving the internal stress may be insignificant. If the temperature is more than 100 캜, the film may be deteriorated.

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.

Example  One

A transparent unoriented polyvinyl alcohol film (PE60, average degree of polymerization of 2400, manufactured by KURARAY) having a width of 100 cm and a thickness of 30 μm and 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 immersed in an aqueous solution for dyeing at 30 DEG C containing 1.25 mM / L of iodine, 1.25% by weight of potassium iodide and 0.3% by weight of boric acid for 2 minutes and 30 seconds, and stained. 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 film was stretched at a draw ratio of 1.7 times while immersing it in a crosslinking aqueous solution at 59 DEG C containing 11 wt% of potassium iodide and 2 wt% of boric acid for 26 seconds (first crosslinking step) and crosslinking. Thereafter, it was immersed in a crosslinking aqueous solution of 59 ° C containing 11% by weight of potassium iodide and 2% by weight of boric acid for 20 seconds (second crosslinking step) and stretched at a stretching ratio of 1.34 times while crosslinking. Then, the coated film was stretched 1.01 times while immersing for 10 seconds in a complementary color aqueous solution containing 50% by weight of potassium iodide and 1% by weight of boric acid. At this time, the total cumulative stretching ratio of the swelling, dyeing, crosslinking and complementary phases was set to be six times.

After completion of the complementary color step, the pre-heat treatment was performed. After the pre-heat treatment, water was washed for 7 seconds in an aqueous solution at 6 ° C to remove impurities on the surface of the polarizer. After the washing with water was completed, the polarizer was dried to prepare a low shrinking polarizer.

As a far infrared (IR) heater, a Heraeus Twin Tube transparent quartz glass infrared heater was used, and the wavelengths of Fast Response Medium wave (1.5 μm lamp) and Medium wave (2.5 μm lamp) were used.

Example  2 to 16 and Comparative Example  1 to 5

Polarizers were prepared in the same manner as in Example 1 except that the pre-heat treatment and drying conditions shown in Table 1 were changed.

division Line-heat treatment dry Calories (Kcal) infrared ray sirocco calorie
(Kcal) infrared ray sirocco Film surface temperature (캜) time
(minute) wavelength
(탆) Hot air temperature
(° C) time
(minute) Drying furnace temperature (캜) time
(minute) Infrared wavelength
(탆) Hot air temperature
(° C) time
(minute) Example 1 0.1 0.3 2.5 - - 200 - - - 95 5 90 Example 2 10 0.3 2.5 - - 200 - - - 95 5 90 Example 3 50 0.3 2.5 - - 200 - - - 95 5 90 Example 4 100 0.3 2.5 - - 200 - - - 95 5 90 Example 5 250 0.3 2.5 - - 200 - - - 95 5 90 Example 6 500 0.3 2.5 - - 200 - - - 95 5 90 Example 7 100 0.3 1.5 - - 200 - - - 95 5 90 Example 8 100 0.3 1.5 - - 200 90 One 1.5 - - 88 Example 9 100 0.3 1.5 - - 300 98 One 1.5 - - 95 Example 10 100 0.3 1.5 - - 500 106 One 1.5 - - 100 Example 11 200 - - 105 0.5 200 - - - 95 5 90 Example 12 200 - - 105 0.5 200 90 One 1.5 - - 88 Example 13 0.05 0.3 2.5 - - 200 - - - 95 5 90 Example 14 600 4 2.5 - - 200 - - - 95 5 90 Example 15 500 6 2.5 - - 200 - - - 95 5 90 Example 16 100 0.3 2.5 - - 500 87 6 1.5 - - 84 Comparative Example 1 - - - - - 200 - - - 95 5 90 Comparative Example 2 - - - - - 350 - - - 100 5 94 Comparative Example 3 - - - - - 200 90 One 1.5 - - 88 Comparative Example 4 - - - - - 300 98 One 1.5 - - 95 Comparative Example 5 - - - - - 600 - - - 100 7 96

Experimental Example

1. Transmittance and orthogonal b measurement

The polarizers prepared in Examples and Comparative Examples were cut into a size of 4 cm x 4 cm, and the transmittance and the orthogonal b were measured with an ultraviolet ray spectrophotometer (V-7100, JASC Co.).

When the normal orthogonal b value is -1.0 or less, staining unevenness is observed.

2. Polarization measurement

The polarizers prepared in Examples and Comparative Examples were cut into a size of 4 cm x 4 cm, and then the transmittance was measured with an ultraviolet ray spectrophotometer (V-7100, manufactured by JASC Corporation). At this time, the polarization degree is defined by the following equation (1).

[Equation 1]

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) .

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.

3. Measure A700

The A700 of the polarizer prepared in Examples and Comparative Examples was defined by the following formula (2).

&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 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 ID = 0.0 &gt; 700nm &lt; / RTI &gt; wavelength)

4. Measurement of contraction force

The polarizers prepared in Examples and Comparative Examples were cut into a size of 3.0 cm x 2 mm, and then the shrinkage force was measured with DMA Q800 (dynamic mechanical analyzer, TA corporation). At this time, the pre-load was used to measure the pre-load to maintain the polarizer before the measurement.

5. Yellow  Confirmation of occurrence

The polarizers prepared in Examples and Comparative Examples were observed with naked eyes to confirm whether yellowing occurred.

○: No yellowing occurred

△: Yellowing occurs in some regions of the polarizer

X: Yellowing occurs throughout the polarizer

division Transmittance
(%) Orthogonal b * Polarization degree
(%) A700
(PVA-I ₅ Complex amount) Contraction force
(N) Yellow Example 1 43.1 -0.8 99.991 4.12 3.9 ○ Example 2 43.1 -0.7 99.992 4.15 3.8 ○ Example 3 43.0 -0.6 99.994 4.09 3.8 ○ Example 4 43.2 -0.3 99.996 4.02 3.7 ○ Example 5 43.1 -0.1 99.997 3.99 3.7 ○ Example 6 43.0 -0.1 99.997 4.02 3.7 ○ Example 7 43.0 -0.3 99.996 4.11 3.6 ○ Example 8 43.1 -0.2 99.996 4.23 2.9 ○ Example 9 42.9 -0.3 99.995 4.32 2.5 ○ Example 10 43.0 -0.4 99.995 4.40 2.4 ○ Example 11 43.0 -0.7 99.994 4.04 3.8 ○ Example 12 42.9 -0.7 99.994 4.11 3.0 ○ Example 13 43.0 -0.9 99.990 4.01 4.1 ○ Example 14 43.6  0.1 99.990 4.11 3.7 △ Example 15 42.9 -0.7 99.994 4.09 4.0 ○ Example 16 43.0 -0.3 99.994 4.14 3.3 ○ Comparative Example 1 43.1 -1.5 99.981 4.04 4.4 ○ Comparative Example 2 43.0 -1.3 99.983 3.88 3.8 ○ Comparative Example 3 43.0 -1.2 99.990 4.25 2.8 ○ Comparative Example 4 43.1 -1.7 99.978 4.43 2.5 ○ Comparative Example 5 43.6 -1.2 99.965 4.25 2.5 X

Referring to Table 2, the polarizer of Example has high orthogonal b value, no staining unevenness, and high degree of polarization. Especially, in Examples 8, 9, 10 and 12 in which infrared irradiation was performed in the drying step, it was confirmed that the value of A700 was large and the shrinking force of the polarizer was low.

However, the polarizer of the comparative example had a low orthogonal b value, resulting in uneven dyeing.

Claims (8)

In the order of the swelling step, the dyeing step, the stretching step, the crosslinking step, the complementary coloring step, the pre-heat treatment step, the washing step and the drying step of the film for forming a polarizer,
The crosslinking step is carried out by immersing the polarizer-forming film in a crosslinking solution containing a boric acid compound,
Wherein the pre-heat treatment step and the drying step are performed by irradiating infrared rays having a wavelength of 1.5 to 3 占 퐉 so that the polarizer-forming film having a unit volume of 5 to 75 cm ³ receives a heat quantity of 0.1 Kcal to 500 Kcal.
delete delete delete delete delete The method of manufacturing a polarizer according to claim 1, wherein the surface temperature of the polarizer-forming film in the drying step is 50 to 100 ° C. delete