KR20150039983A - Method for preparing polarizer and polarizer - Google Patents

Abstract

The present invention relates to a method for preparing a polarizer, and a polarizer. More specifically, the method for preparing a polarizer performs a process including a swelling step, a dyeing step and a cross-linking step on a polyvinyl alcohol-based film. Provided are a method for preparing a polarizer and a polarizer having significantly improved moist-heat resisting properties while maintaining polarizing properties and heat resistance equal to or greater than the existing polarizing properties by using a cross-linking solution containing a compound having an oxazoline group and a boron compound at both ends.

Description

METHOD FOR PREPARING POLARIZER AND POLARIZER [0001]

The present invention relates to a method for producing a polarizer excellent in heat and humidity resistance.

The polarizing plate has a structure in which a transparent protective film is laminated on both sides or one side of a polarizer made of a polyvinyl alcohol-based resin in which dichroic dye is adsorbed and oriented.

A polarizer using iodine as a dichroism pigment is an iodine polarizer, and a polarizer using a dichroic dye is a dye-based polarizer. The dual iodine polarizer is widely used because it has high transmittance and high polarization (high contrast) as compared with the dye type polarizer.

Since the polarizer is a highly stretched film, it shrinks in the stretching direction under heating conditions, deteriorating the heat resistance characteristics of the polarizing plate, absorbing moisture in the humidifying condition, causing swelling of the film, thereby degrading the dyeing color and deteriorating optical characteristics .

Boric acid is used as a crosslinking agent in order to suppress shrinkage under the heating conditions and swelling phenomenon under humidifying conditions. However, when boric acid is used alone, the water content is lowered under the heating condition, and the boric acid crosslinking proceeds further. Since the spatial structure of the polarizer matrix resin is changed by the boric acid crosslinking, the stability of the iodine complexes having different absorption wavelengths is different from each other, and the transmittance of the red color region is increased, resulting in a problem of being observed in red.

In order to suppress the boric acid crosslinking, various methods using aldehyde as a crosslinking agent have been proposed.

Specifically, in order to improve the dimensional stability of a polarizer formed of a polyvinyl alcohol-based film, a method of using a crosslinked solution containing a dialdehyde compound such as glyoxal as a dyed polyvinyl alcohol film (Japanese Patent Publication No. 3357109) and A method of using a crosslinking solution containing a trialdehyde compound (JP-A-2008-197510) is proposed.

However, the dialdehyde and trialdehyde compounds of the above-mentioned technology are aliphatic compounds, and since the reactivity with the hydroxyl group of the polyvinyl alcohol is low, the unreacted aldehyde group is contained at a certain level even after the production process of the polarizing plate is completed, And the structure of the PVA matrix is changed to cause a change in color.

In addition, as in the case of using boric acid under the moisture-resistant condition, there is a problem that the cross-linking is hydrolyzed, thereby causing a change in optical characteristics (such as color change).

The present invention uses a crosslinked aqueous solution which has a high reactivity with a hydroxyl group in PVA and can lower the content of residual crosslinking functional groups. By using the above-mentioned crosslinked aqueous solution, it is possible to suppress the change of hue under heat-resistant condition and to form an irreversible covalent bond, and hydrolysis reaction is not carried out, so that the equilibrium state of iodide ion can be maintained under the anti- And it is an object of the present invention to provide a method of manufacturing a polarizer.

In order to accomplish the above object, the present invention provides a method of producing a polarizer that performs a process comprising a swelling step, a dyeing step and a crosslinking step in a polyvinyl alcohol film, wherein the crosslinking step is a step in which the compound having an oxazoline group And a method for producing a polarizer using a crosslinked aqueous solution containing a boron compound.

The compound having an oxazoline group at both terminals may be a compound represented by the following formula (1).

(Wherein R is a direct bond, a C ₁ -C ₁₂ aliphatic hydrocarbon, a C ₁ -C ₁₂ aliphatic hydrocarbon having an ether group, or a C ₄ -C ₈ aromatic hydrocarbon).

Preferably, the compound of formula (1) may be at least one compound selected from the group consisting of the following formulas (2) to (8).

The compound of Formula 1 may be contained in an amount of 0.5 to 10% by weight based on 100% by weight of the aqueous crosslinked solution.

The boron compound may be contained in an amount of 1 to 10% by weight based on 100% by weight of the aqueous crosslinked solution.

At least one of the swelling step, the dyeing step and the crosslinking step may include a uniaxially stretching step.

The crosslinking step may use an aqueous crosslinking solution containing iodide.

The present invention also provides a polarizer produced by the above method.

The present invention also provides a polarizing plate including the polarizer.

The present invention also provides a display device including the polarizer.

The polarizer manufactured by the method according to the present invention can remarkably improve heat resistance and humid heat resistance while maintaining polarization characteristics equal to or higher than those of the conventional polarizer, and can be usefully used for an LCD polarizer having a large temperature and humidity variation such as LCD navigation and LCD TV There is an advantage.

The present invention relates to a method for producing a polarizer excellent in heat resistance and heat and humidity resistance.

Hereinafter, the present invention will be described in detail.

The method for producing a polarizer according to the present invention is a method for producing a polarizer that performs a process comprising a swelling step, a dyeing step and a crosslinking step in a polyvinyl alcohol film, wherein the crosslinking step is a step of crosslinking a compound having an oxazoline group at both terminals and A crosslinked aqueous solution containing a boron compound is used.

In the present invention, the polarizer means a conventional iodine-based polarizer in which iodine is adsorbed and oriented on a polymer film.

The type of the polymer film for producing the polarizer is not particularly limited as long as it is a dichroic material, that is, a film which can be dyed with iodine. Specifically, the type of the polymer film is 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.

Generally, a method for producing a polarizer is performed by a process including a swelling step, a dyeing step and a crosslinking step, and the step may include a stretching step, a washing step and a drying step. Such a manufacturing method is mainly classified by a stretching method. For example, a dry stretching method, a wet stretching method, or a hybrid stretching method in which the two kinds of stretching methods are mixed can be used. Hereinafter, a method of producing the polarizer of the present invention will be described with reference to a wet drawing method, but the present invention is not limited thereto.

The remaining steps except the drying step are performed in a state in which the polyvinyl alcohol film is immersed in a constant temperature bath filled with one or more kinds of solutions selected from various kinds of solutions.

The swelling step is carried out by immersing the unstretched polyvinyl alcohol 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 polyvinyl alcohol film, Is a step for improving the physical properties of the polarizer by improving the stretching efficiency and preventing uneven dyeing by swelling the film.

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 is preferably 5% by weight or less based on 100% by weight of the aqueous swelling solution, and the content of potassium iodide is preferably 10% by weight or less.

The swelling bath temperature is preferably 20 to 45 캜, more preferably 25 to 40 캜.

The execution time (swelling tank immersion time) of the swelling step is preferably 180 seconds or less, more preferably 90 seconds or less. When the immersion time is within the above range, it is possible to prevent the swelling from becoming excessive and saturation, to prevent breakage due to softening of the polyvinyl alcohol film and to improve the polarization degree by uniformly adsorbing iodine in the dyeing step have.

The stretching step is carried out together with the swelling step, wherein the stretching ratio is about 1.1 to 3.5 times, preferably 1.5 to 3.0 times. If the stretching ratio is less than 1.1 times, wrinkles may occur. If the stretching ratio is more than 3.5 times, initial optical characteristics may become weak.

The dyeing step is a step of dipping the polyvinyl alcohol-based film in a dyeing bath filled with an aqueous solution for dyeing containing a dichroic substance, for example, iodine to adsorb iodine on the polyvinyl alcohol-based film.

The dyeing aqueous solution may comprise water, a water-soluble organic solvent or a mixed solvent thereof and iodine. The content of iodine is preferably 0.4 to 400 mmol / L, more preferably 0.8 to 275 mmol / L, and most preferably 1 to 200 mmol / L with respect to 100 wt% of the aqueous solution for dyeing. To further improve the dyeing efficiency, iodide may be further included as a dissolution aid. As the iodide, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide may be used alone or in combination of two or more. Of these, potassium iodide is preferable in view of high solubility in water. The content of iodide is preferably 0.01 to 10% by weight, more preferably 0.1 to 5% by weight based on 100% by weight of the dyeing aqueous solution.

The temperature of the dye bath is preferably 5 to 42 ° C, more preferably 10 to 35 ° C. The immersion time of the polyvinyl alcohol film in the dyeing bath is not particularly limited, and is preferably 1 to 20 minutes, and more preferably 2 to 10 minutes.

And the stretching step is carried out together with the dyeing step. In this case, the stretching ratio is preferably 1.01 to 2.0 times, and more preferably 1.1 to 1.8 times.

The cumulative stretching ratio up to the dyeing step including the swelling and dyeing steps is preferably 1.2 to 4.0 times. If the cumulative stretching ratio is less than 1.2 times, wrinkles of the film may occur to cause appearance defects. If the cumulative stretching ratio exceeds 4.0 times, the initial optical characteristics may be poor.

The crosslinking step is a step of immobilizing the adsorbed iodine molecules by immersing the dyed polyvinyl alcohol film in a crosslinking aqueous solution so that the dyeability due to physically adsorbed iodine molecules is not lowered by the external environment. Although dichroic dyes are not often eluted in a humidity environment, iodine molecules often dissolve or sublimate depending on the environment when the crosslinking reaction is unstable, and sufficient crosslinking reaction is required. In addition, the crosslinking step is important because, in order to orient the iodine molecules positioned between all the polyvinyl alcohol molecules and the molecules and to improve the optical properties, the crosslinking step generally needs to be elongated to the largest stretching ratio.

The present invention can carry out the crosslinking step composed of a single step or a single step or two steps. The crosslinking step composed of the first step and the second step may be repeated at least two times.

The present invention is characterized in that, in carrying out the crosslinking step, the crosslinking aqueous solution containing a compound having an oxazoline group at both terminals and a boron compound is used.

The compound having an oxazoline group at both terminals acts as an organic cross-linking agent and improves the heat resistance of the produced polarizer. Specifically, since the crosslinking agent forms an irreversible covalent bond, the hydrolysis reaction is not performed, so that the equilibrium state of iodide ion can be maintained under the anti-wet heat condition.

Further, the content of the remaining oxazoline group is reduced due to the high reactivity of the oxazoline group, so that the additional crosslinking reaction under heat-resistant conditions is suppressed to improve the heat resistance.

In addition, nitrogen and oxygen atoms, which are hydrogen bonding groups in the molecule, improve the solubility in water and can improve foreign matter defects due to particle aggregation of the un-dissolved crosslinking agent in the manufacturing process.

The compound having an oxazoline group at both terminals may be a compound represented by the following formula (1).

[Chemical Formula 1]

(Wherein R is a direct bond, a C ₁ -C ₁₂ aliphatic hydrocarbon, a C ₁ -C ₁₂ aliphatic hydrocarbon having an ether group, or a C ₄ -C ₈ aromatic hydrocarbon).

Preferably, the compound of formula (1) may be at least one compound selected from the group consisting of the following formulas (2) to (8).

(2)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

(7)

[Chemical Formula 8]

The compound having an oxazoline group at both ends may contain 0.5 to 10% by weight, preferably 0.8 to 6% by weight, based on 100% by weight of the aqueous crosslinked solution. If the content is less than 0.5% by weight, the effect of the organic crosslinking agent may be insufficient and it may be difficult to impart flexibility. When the content exceeds 10% by weight, the effect of the organic crosslinking agent is excessively activated, Can be lowered.

The boron compound imparts short crosslinking and rigidity to suppress wrinkling during processing, thereby improving handling properties and forming iodine alignment. Such boron compounds include boric acid, sodium borate and the like, and boric acid is preferred considering the pH at which the crosslinking reactivity can be promoted.

The content of the boron compound is preferably 1 to 10% by weight, more preferably 2 to 6% by weight based on 100% by weight of the aqueous crosslinked solution. When the content is less than 1% by weight, the crosslinking effect of the boron compound is reduced and it is difficult to impart rigidity. When the content is more than 10% by weight, the crosslinking reaction of the inorganic crosslinking agent is excessively activated and the crosslinking reaction of the organic crosslinking agent is difficult to proceed effectively.

When the initial optical properties and the heat resistance are taken into account simultaneously, the amount of the boron compound and the compound having an oxazoline group at both terminals is preferably from 1: 0.1 to 1.5, more preferably from 1: 0.3 to 1.0, It is good to do.

The crosslinked aqueous solution may further contain water, which is a solvent, and iodide.

Iodide is used to prevent the uniformity of the degree of polarization in the plane of polarizers and the desorption of dyed iodine. The iodide may be the same as that used in the dyeing step, and the content thereof may be 0.05 to 15% by weight, preferably 0.5 to 11% by weight, based on 100% by weight of the aqueous crosslinked solution. If the content is less than 0.05% by weight, the iodide ions in the film may escape to increase the transmittance. If the content exceeds 15% by weight, the iodide ions in the aqueous solution may penetrate into the film, thereby decreasing the transmittance.

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

The stretching step may be performed together with the crosslinking step, and in this case, it is preferable that the total stretching ratio is 3.0 to 8.0 times. As described above, the stretching step may be performed in conjunction with the swelling step, the dyeing step, the crosslinking step, and may be carried out with an independent stretching step using a separate stretching vessel filled with the eluting aqueous solution after the crosslinking step

It is preferable that the present invention is stretched so that the total cumulative stretching ratio is 4.0 to 7.0 times. In the present specification, "cumulative stretching ratio" represents the value of the product of the stretching ratio at each step.

The crosslinked and stretched polyvinyl alcohol film is dipped in a water bath filled with aqueous solution for washing to remove unnecessary residues such as boric acid attached to the polyvinyl alcohol film in the previous steps.

The aqueous solution for washing may be water, and iodide may be further added thereto.

The temperature of the water bath is preferably 10 to 60 ° C, more preferably 15 to 40 ° C.

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

The drying step is a step of drying the washed polyvinyl alcohol-based film and further improving the orientation of the iodine molecules dyed by the necking by drying, thereby obtaining a polarizer excellent in optical characteristics.

As the drying method, natural drying, air drying, heating and drying, far infrared ray drying, microwave drying, hot air drying and the like can be used. Recently, microwave drying in which only water in the film is activated and dried is newly used, Drying is mainly used. For example, it may be hot air dried at 20 to 90 DEG C for 1 to 10 minutes. The drying temperature is preferably low in order to prevent deterioration of the polarizer, more preferably 80 ° C or lower, and most preferably 60 ° C or lower.

In addition, the present invention provides a polarizing plate in which a protective film is laminated on at least one surface of a polarizer produced by the above production method, and a display device including the polarizing plate.

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

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

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

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Example  One

1중량%가 함유된 50℃의 제1 및 제2 가교용 수용액에 각각 2분, 1분 동안 침지하여 가교시켰다. 이때, 제1 및 제2 가교단계에서 총 연신비가 3.75배가 되도록 연신하여 총 누적 연신비가 6.8배가 되도록 하였다. 가교가 완료된 후 폴리비닐알코올 필름을 70℃의 오븐에서 4분 동안 건조시켜 편광자를 제조하였다.(VF-PS 70 mu m, Kuraray) having an average degree of polymerization of about 2,400, a degree of saponification of 99.9 mol% or more, and a thickness of about 55 mu m was immersed in water (deionized water) at 30 DEG C for 2 minutes Followed by immersion and swelling. Thereafter, it was dipped in an aqueous solution for dyeing at 30 DEG C containing 3.5 mmol / L of iodine and 2% by weight of potassium iodide for 4 minutes and stained. At this time, stretching was performed at 1.3 times and 1.4 times at the swelling and dyeing stages, respectively. Then, 10 wt% of potassium iodide, 3.5 wt% of boric acid,

Was immersed in the first and second aqueous crosslinking solutions at 50 占 폚 containing 1% by weight for 2 minutes and 1 minute, respectively, for crosslinking. At this time, the first and second crosslinking steps were performed such that the total stretching ratio was 3.75 times, so that the total cumulative stretching ratio was 6.8 times. After the crosslinking was completed, the polyvinyl alcohol film was dried in an oven at 70 DEG C for 4 minutes to prepare a polarizer.

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

At this time, the aqueous adhesive was mixed with a 10% aqueous solution of a modified polyvinyl alcohol (trade name: Gosepaima Z200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and sodium glyoxylate (product name: SPM-01, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) By weight were used.

Example  2-9 and Comparative Example  1-4

The crosslinking step was carried out in the same manner as in Example 1 except that the crosslinked aqueous solution of Table 1 was used to prepare a polarizer.

division
(weight%) Step 1 Crosslinked aqueous solution Two-step crosslinked aqueous solution gun
Stretching cost
(ship) Potassium iodide Boric acid The compound having an aldehyde group (% by weight) Potassium iodide Boric acid The compound having an aldehyde group (% by weight) Example 1 10 3.5 (2) 10 3.5 (2) 3.75 Example 2 10 3.5 (3) 10 3.5 (3) 3.75 Example 3 10 3.5 (2) 10 3.5 (2) 3.75 Example 4 10 3.5 (2) 10 3.5 (2) 3.75 Example 5 10 3.5 (3) 10 3.5 (3) 3.75 Example 6 10 3.5 (5) 10 3.5 (5) 3.75 Example 7 10 3.5 (2) - - - 3.75 Example 8 - - - 10 3.5 (2) 3.75 Example 9 10 3.5 - 10 - (2) 3.75 Comparative Example 1 10 3.5 - 10 3.5 - 3.75 Comparative Example 2 10 3.5 - - - - 3.75 Comparative Example 3 10 3.5 Glyoxal (1) 10 3.5 Glyoxal (1) 3.75 Comparative Example 4 10 3.5 Glutaraldehyde (1) 10 3.5 Glutaraldehyde (1) 3.75

화학식 3:

화학식 5:

(2)

(3)

(5)

Test Example

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

1. Optical characteristics (polarization degree, transmittance)

The prepared polarizer was cut into a size of 4 cm x 4 cm and the transmittance was measured using an ultraviolet-visible light spectrometer (V-7100, manufactured by JASCO). At this time, the polarization degree is defined by the following equation (1).

(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) .

2. Heat resistance

The prepared polarizer was cut into a size of 1 cm x 3 cm with respect to the width direction (longitudinal direction, TD) and the longitudinal direction (transverse direction, MD), and then left under heat-resistant conditions at 100 ° C for 24 hours. The color change before and after the heat-resistant condition was confirmed by visual observation and transmission spectrum measurement with a UV-VIS measuring device, and color change (red color appearance) was confirmed.

 [Assessment Methods]

X: The color change was visually observed.

Δ: The color change was observed to a slight extent by the naked eye.

○: Color change was not observed with naked eyes.

◎: No difference was observed in the transmission spectrum.

3. Humidity Durability

The prepared polarizer was cut into a size of 1 cm x 3 cm with respect to the width direction (longitudinal direction, TD) and the longitudinal direction (transverse direction, MD), and then left under the wet heat resistance condition at 60 DEG C and 90% for 48 hours. The color change before and after the wet heat treatment condition was confirmed by visual observation and transmission spectral measurement with a UV-VIS measuring device, and color change (red color appearance) was confirmed.

 [Assessment Methods]

X: The color change was visually observed.

Δ: The color change was observed to a slight extent by the naked eye.

○: Color change was not observed with naked eyes.

◎: No difference was observed in the transmission spectrum.

division Optical properties (%) Heat resistance Wet heat Polarization degree Transmittance Example 1 99.9 42.5 ◎ ◎ Example 2 99.9 42.5 ◎ ◎ Example 3 99.9 42.4 ◎ ◎ Example 4 99.9 42.5 ○ ◎ Example 5 99.9 42.6 ◎ ◎ Example 6 99.9 42.5 ◎ ◎ Example 7 99.9 42.5 ◎ ◎ Example 8 99.9 42.5 ◎ ◎ Example 9 99.9 42.6 ◎ ◎ Comparative Example 1 99.9 42.6 × × Comparative Example 2 99.9 42.5 × × Comparative Example 3 99.9 42.4 △ △ Comparative Example 4 99.9 42.5 △ △

As shown in Table 2, the polarizers of Examples 1 to 10 prepared using a crosslinked aqueous solution containing a compound having an oxazoline group at both terminals and a boron compound according to the present invention had a degree of polarization equal to or higher than that of Comparative Examples 1 to 4 It was confirmed that the heat resistance and the humid heat resistance were remarkably improved while maintaining the transmittance.

Claims (10)

A method for producing a polarizer for performing a process comprising a swelling step, a dyeing step and a crosslinking step in a polyvinyl alcohol film,
Wherein the crosslinking step uses a crosslinked aqueous solution containing a compound having an oxazoline group at both terminals and a boron compound.
The method for producing a polarizer according to claim 1, wherein the compound having an oxazoline group at both terminals is a compound represented by the following formula
[Chemical Formula 1]

(Wherein R is a direct bond, a C ₁ -C ₁₂ aliphatic hydrocarbon, a C ₁ -C ₁₂ aliphatic hydrocarbon having an ether group, or a C ₄ -C ₈ aromatic hydrocarbon).
The method of claim 2, wherein the compound of Formula 1 is at least one selected from the group consisting of the following Formulas 2 to 8:
(2)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

(7)

[Chemical Formula 8]

[2] The method of producing a polarizer according to claim 1, wherein the compound of Formula 1 is contained in an amount of 0.5 to 10% by weight based on 100% by weight of the crosslinked aqueous solution.
The method of producing a polarizer according to claim 1, wherein the boron compound is contained in an amount of 1 to 10% by weight based on 100% by weight of the aqueous crosslinked solution.
The method of manufacturing a polarizer according to claim 1, wherein at least one of the swelling step, the dyeing step and the crosslinking step comprises a uniaxially stretching step.
The method of manufacturing a polarizer according to claim 1, wherein the crosslinking step uses an aqueous crosslinking solution containing iodide.
A polarizer produced by the method of any one of claims 1 to 7.
A polarizer comprising the polarizer of claim 8.
A display device including the polarizer of claim 9.