KR20080000877A - Surface modified polarizing film and its manufacturing method - Google Patents

Abstract

The present invention discloses a polarizing film containing iodine or a dichroic dye in a polyvinyl alcohol-based substrate film whose surface is modified by ultraviolet irradiation, which is excellent in polarization efficiency and improves transmittance and ultimately occurs from a backlight or the like. The effect of not impairing the transmission of light can be obtained, and in particular, it is possible to provide an economical and easy method for improving the transmittance even by a simple treatment of irradiating ultraviolet rays to the polarized film on which the adsorption of iodine or dyeing is completed.

Description

Surface modified polarizing film and its manufacturing method {Polarizing film and Manufacturing method for the same}

1 is a graph measuring reflectance of each PVA film obtained by varying the amount of ultraviolet radiation,

Figure 2 is a graph of the result of measuring the surface contact angle of the PVA film according to the ultraviolet radiation dose using three liquids, water, glycerin, diiodomethane,

3 is a graph showing the surface energy of the PVA film according to the amount of ultraviolet radiation,

4 is a graph showing the contact angle of the polarizing film obtained according to Example 1,

5 is a graph showing the surface energy of the polarizing film obtained according to Example 1,

6 is a graph showing the contact angle of the polarizing film obtained according to Example 2,

7 is a graph showing the surface energy of the polarizing film obtained according to Example 2,

8 is a graph showing the contact angle of the polarizing film obtained according to Example 3,

9 is a graph showing the surface energy of the polarizing film obtained according to Example 3,

10 is a graph showing the contact angle of the polarizing film obtained according to Example 4,

11 is a graph showing the surface energy of the polarizing film obtained according to Example 4,

12 is a graph showing the transmittance and polarization efficiency of the polarizing film obtained according to Examples 1 and 2,

13 is a graph showing the transmittance and polarization efficiency of the polarizing film obtained according to Examples 3 and 4.

The present invention relates to a surface-modified polarizing film and a method for manufacturing the same, and more particularly, to a polarizing film having improved transmittance by including iodine or a dichroic dye in a substrate film whose surface is modified by ultraviolet irradiation, and a method of manufacturing the same. It is about.

1928 E.H. The polarizer film first studied by Land was extremely limited in its industrial use. However, as the modern industrial society develops into a high information age, the demand is increasing in earnest. This is a result of the increasing importance of the electronic display.

Commercially available polarizing films can be classified into various types according to their types and performances. First, iodine polarizing films are polarizing films for high-definition LCDs, which mainly have high transmittance and high polarization characteristics, and absorb light in the visible region in a transparent PVA film. Refers to a film using iodine having high dichroism to impart the ability. Most of the polarizing films used in LCDs to date are iodine polarizing films. Secondly, a dye-based polarizing film, which has been studied to solve the problem of durability due to the sublimability of iodine, may be mentioned. This is a highly durable polarizing film with a small change in optical properties even under high temperature and high humidity conditions, and has been used for LCDs requiring high durability due to its high durability. In addition, in the case of the dye-based polarizing film is relatively easy to control the color can be produced a polarizing film of various colors, which is also used in the field of sunglasses and the like. Thirdly, it is a polarizing film mainly used for a high speed response liquid crystal display (STN-LCD: Super Twisted Nematic LCD) called a retardation polarizing film. This makes a wide variety of products depending on the angle applied to the retardation film having a characteristic in the polarizing film. The retardation film is a film that compensates for the phase difference generated in the liquid crystal and currently, a polycarbonate-based retardation film is mainly used. Fourth, a semi-transmissive reflective polarizing film having both transmissive and reflective characteristics may be mentioned. Semi-transparent polarizing film is involved in power consumption efficiency, which is one of the most important factors in the display of mobile devices, which has a problem of shortening the use time of the product when the power consumption is high. It is a functional film used as a material for the bottom plate used in semi-transmissive LCD by adding a reflection function that utilizes external light instead of a transmissive product. There are various kinds of such semipermeable films depending on the materials and property values used. And a product in which a pigment is added to an adhesive to control transmittance (ST type) and a product (TDF, 3M company) that stacks hundreds of layers of polymer thin films having different refractive indices. Fifthly, the highly reflective semi-transmissive polarizing film has been used to increase the reflectance and diffuse adhesive by using metal deposition film instead of the translucent polarizing film using the conventional pigment to reduce power consumption and make the appearance of the display more clear in recent STN-LCDs. It is a polarizing film that improved the appearance using. Sixth, the polarizing film (AG / AR) which prevented surface reflection is mentioned. There are two types of surface anti-reflection: AG (Anti-glare) processing and AR (Anti-reflection) processing. The AG process forms an irregular surface on the surface of the film, which diffusely reflects external light from the surface, and exhibits antireflection effect. The AR process uses a deposition method or a coating method to deposit thin films of different layers on the surface of the film by vapor deposition or coating. By forming, it exhibits an antireflection effect. In general, the reflectance of the polarizing film without antireflection processing is about 4%, the AG film has a reflectance of about 2%, and the AR film has a value of less than 1% of reflectance. Finally, there is a reflective polarizing film, which is a product made by laminating a metal deposition reflector film on a general iodine polarizing film, which is used in a reflective LCD.

In general, a polarizing film uses a film having polarization characteristics treated with iodine or dichroic dye in PVA as a polarizer, and forms a protective layer to prevent deformation of the film due to high sublimation and low durability of iodine.

However, in the case of a film treated with iodine or dichroic dye in PVA, especially in a product requiring high brightness such as LCD, the polarization efficiency should be high and the transmittance is most preferable. This is because the light emitted from the backlight unit is a polarizing film. This reduces the amount of light emitted when reflected.

Conventionally, although the method of improving the transmittance of the polarizing film has been used a method of adjusting the draw ratio of the PVA base film, there is an urgent need for another method for more easily controlling the transmittance.

Thus, the present invention, while seeking a way to improve the transmittance while having a high polarization efficiency, when the surface of the polarizing film is modified by ultraviolet irradiation, the surface has a certain hydrophobicity, the surface energy is lowered and the reflectance is lowered The present invention has been accomplished by knowing that the same requirements can be satisfied.

Accordingly, an object of the present invention is to provide a polarizing film having high polarization efficiency and improved transmittance.

Another object of the present invention is to provide a method of easily manufacturing a polarizing film having high polarization efficiency and improved transmittance.

Polarizing film of the present invention for achieving the above object is characterized in that it comprises an iodine or a dichroic dye in the polyvinyl alcohol-based substrate film is modified surface by ultraviolet irradiation.

In addition, the polarizing film of the present invention is characterized in that the transmittance is 22 to 55% and the polarization efficiency is 74 to 99.9%.

In addition, the polarizing film of the present invention is characterized in that the polyvinyl alcohol-based film surface is modified by ultraviolet irradiation in the presence of ozone.

In addition, the polarizing film of the present invention is characterized in that the polyvinyl alcohol-based film surface is modified by ultraviolet irradiation so that the amount of ultraviolet irradiation 0.53 to 42.4J / ㎠.

In another aspect, the present invention is a method of manufacturing a polarizing film comprising the step of adsorbing an iodine compound or dyeing a dichroic dye before, during or after uniaxial stretching of the polyvinyl alcohol-based film, and fixing it in an aqueous solution of a crosslinking agent, The manufacturing method of the polarizing film which performs the step of modifying a film surface through ultraviolet irradiation before extending | stretching after dyeing of a dichroic dye or adsorption of an iodine compound to a polyvinyl alcohol-type film is also characteristic.

In another aspect, the present invention is a method for producing a polarizing film comprising adsorbing an iodine compound or dyeing a dichroic dye after uniaxial stretching of the polyvinyl alcohol-based film, and then fixing it in an aqueous solution of a crosslinking agent, polyvinyl alcohol The manufacturing method of the polarizing film which performs the process of modifying a film surface by ultraviolet irradiation after extending | stretching after extending | stretching after dyeing of a dichroic dye or adsorption of an iodine compound to a system film is also characteristic.

In another aspect, the present invention is a method of manufacturing a polarizing film comprising the step of adsorbing an iodine compound or dyeing a dichroic dye after uniaxial stretching of the polyvinyl alcohol-based film, and then fixing it in an aqueous solution of a crosslinking agent, after the fixing step In the method of manufacturing a polarizing film to perform the step of modifying the film surface through ultraviolet irradiation in its characteristics.

In the manufacturing method as described above, the ultraviolet irradiation is characterized in that it is carried out so that the irradiation amount 0.53 to 42.4J / ㎠.

In the above manufacturing method, ultraviolet irradiation is characterized in that it is carried out in the presence of ozone (O ₃ ).

The present invention will be described in more detail as follows.

The present invention relates to a surface-modified polarizing film, which has a transmittance of 22 to 55% and a polarization efficiency of 74 to 99.9%, and is a polarizing film having improved transmittance of the polarizing film through a simple process called ultraviolet irradiation. .

At this time, the ultraviolet irradiation is preferably carried out in the presence of ozone, that is, UV / O ₃ treatment conditions, the ultraviolet irradiation method containing ozone does not require a vacuum and the size and shielding of the device is not required, It has advantages such as low cost of equipment and environmental friendliness. It is also advantageous for oxidation.

In this case, the amount of UV radiation is preferably 0.53 to 42.4 J / cm 2. As the amount of UV radiation increases, the contact angle of water on the surface of the PVA film increases and the surface energy decreases, and the reflectance decreases. In this case, haze may occur on the surface of the polarizing film, which is not preferable. In addition, when the amount of UV radiation is too small, the surface modification is insignificant, it is difficult to express the above characteristics. Most preferably, the UV irradiation amount is 0.53 to 2.12 J / cm 2.

In general, a polarizing film is prepared by adsorbing an iodine compound or dyeing a dichroic dye before uniaxial stretching of polyvinyl alcohol-based film, or after stretching, and then fixing and drying it in an aqueous solution of a crosslinking agent. May be stretched in the crosslinking agent aqueous solution.

In the manufacturing process of such a polarizing film, the ultraviolet irradiation as described above may first modify the surface of the film through ultraviolet irradiation in the step before the stretching is performed after the adsorption of iodine or dyeing.

Secondly, the surface of the film may be modified by UV irradiation after iodine adsorption or dye dyeing is completed and stretching is completed.

Third, the film may be modified through ultraviolet irradiation after the manufacture of the polarizing film is completed.

In addition to the above-described application process, if the ultraviolet irradiation can be allowed anywhere in the manufacturing step of the polarizing film, it is of course possible to modify the film surface through ultraviolet irradiation.

Preferably, the manufacturing of the polarizing film is completed, and then the surface of the film is modified by UV irradiation. In this case, in an application requiring improvement of the transmittance, the polarized film in the form of a finished product is taken through the UV irradiation process only. Can be improved to a certain range, which is particularly useful commercially.

According to the results of the present inventors, even after the ultraviolet irradiation, the adsorption of the iodine compound or the dyeing was performed, and the permeability was improved. As a result, the surface of the film was modified through the ultraviolet irradiation.

Therefore, the required transmittance can be easily adjusted by adjusting the amount of ultraviolet radiation, but the excessive improvement of the transmittance can lower the polarization efficiency, it is preferable to perform the ultraviolet irradiation so that the amount of ultraviolet irradiation 0.53 ~ 42.4J / ㎠.

Particularly preferably, ultraviolet irradiation is performed in the presence of ozone, which is the same as the reason mentioned above.

When the ultraviolet radiation is, according the experimental bar to confirm that modify the surface of the film saponification degree will be about 95%, and the stereoregularity castle ultraviolet ray irradiation processing to the PVA film of atactic _{(atatic) (UV / O 3} ), specifically As an irradiator (UV-cleaner, manufactured by Jelight) having an output of 17.2 mW / ㎠ As a result of measuring the reflectance of the PVA film treated by varying the irradiation dose, the reflectance change as shown in FIG. 1 was shown. It can be seen that as the amount of UV radiation increases, the reflectance is remarkably decreased in the short wavelength region of 450 nm or less, which may be due to the unevenness of the film surface due to UV irradiation.

In addition, the contact angle was measured by a sessile drop method using a static contact angle meter (Phoenix300 Co.) equipped with a CCD (Charge Coupled Device) to measure the surface contact angle of the UV / O ₃ irradiated PVA film. Using the three liquids, glycerine and diiodomethane, the contact angles of the specimens were measured five times or more at 20 ° C. and 65% RH, and then the average value was obtained. The results are shown in FIGS. 2 and 3. According to Figure 2 the contact angle for diiodomethane and glycerin decreases as the UV irradiation dose can be seen that the contact angle of water increases. Also, according to FIG. 3, it can be seen that the surface energy (total surface energy) of the film decreases as the amount of ultraviolet irradiation increases. It can be seen that the reduction of the Lewis acidic acid base component affected the total surface energy reduction. 2 and 3 show that the surface of the film is hydrophobized by ultraviolet irradiation.

In the present invention, the type of PVA film, the stretching method, the iodine adsorption or dye dyeing method, the fixing method using a crosslinking agent, etc. are not particularly limited, but as an example, the polyvinyl alcohol film used in dry uniaxial stretching may be used. Examples of the polyvinyl alcohol polymer include those obtained by polymerizing vinyl acetate and then saponifying or copolymerizing monomers copolymerizable with a small amount of unsaturated carboxylic acid, unsaturated sulfonic acid, and cationic monomer to vinyl acetate. Although the polymerization degree of a polyvinyl alcohol-type polymer is not restrict | limited in particular, Any thing can be used, In terms of solubility with respect to the water of a film, only the average degree of polymerization 500-1 is preferable, More preferably, it is 1000-6000. The saponification degree is preferably 75 mol% or more, and more preferably 95 to 100 mol%. The thickness of a film is 5-150 micrometers, Preferably it is 10-100 micrometers.

The dry uniaxial stretching method is not particularly limited, but for example, a method of rolling with a pressure roll by applying a rear tension, a method of contacting and stretching a heating roll while applying a rear tension to a film, between rolls installed in or outside a heating oven And stretching using a heating roll such as passing through a heating roll and compressing stretching, and stretching using a tenter stretching machine. The draw ratio is preferably 2 times or more, more preferably 2 to 6 times, particularly preferably 2 to 5 times.

As for the heating roll or oven temperature at the time of extending | stretching, 50-200 degreeC is preferable, Especially preferably, it is 60-150 degreeC.

And the composition of the iodine containing aqueous solution for iodine adsorption is 0.01-0.5 weight part of iodine, 0.05-50 weight part of potassium iodides per 100 weight part of water normally, and the temperature of aqueous solution is 10-50 degreeC normally.

The composition of the dichroic dye-containing aqueous solution is usually 0.001 to 1 part by weight of dichroic dye with respect to 100 parts by weight of water. The temperature of aqueous solution is the range of 10-80 degreeC normally. The immersion time is not particularly limited, but is usually 1 second to 10 minutes, preferably 5 seconds to 5 minutes. In addition to the aqueous solvent, a small amount of an organic solvent compatible with water may be contained.

Uniaxial stretching is preferably performed prior to adsorption of iodine or dyeing of the dye, but may be thereafter.

Meanwhile, as the crosslinking agent, boric acid, borax, glyoxal or glutaraldehyde may be used, but is not limited thereto. The composition of the PVA crosslinking agent-containing aqueous solution is usually 0.1 to 15 parts by weight or 0 to 15 parts by weight of potassium iodide, alone or in combination with 100 parts by weight of water, and the temperature of the aqueous solution is usually in the range of 10 to 90 ° C.

The immersion time is not particularly limited, but is usually 1 second to 15 minutes, preferably 5 seconds to 10 minutes. In addition to the aqueous solvent, a small amount of an organic solvent compatible with water may be contained. As the PVA crosslinking agent, boron compounds such as boric acid and borax are preferably used.

The stretching may be further performed in the aqueous solution of the crosslinking agent, in which case the stretching ratio is preferably 1.02 times or more.

Although the thickness of the polarizing film of this invention is not specifically limited, 1-80 micrometers is common and 2-40 micrometers is especially preferable.

Hereinafter, the present invention will be described in detail with reference to Examples. However, the present invention is not limited to the Examples.

Example 1

A polyvinyl alcohol film (manufactured by Nihon Kosei Co., Ltd.) having an average degree of polymerization of 1700 and a film thickness of 100 µm was immersed in an aqueous solution of iodine at 0.02 molar concentration for 2 minutes, followed by stretching in a 40 ° C boric acid bath (concentration 2% by weight), followed by 25 ° C Washed with pure water and dried for 4 minutes at 60 ℃ to obtain a polarizing film (thickness 30㎛).

The irradiated film was controlled by using an irradiator (UVO-cleaner, manufactured by Jelight Co., Ltd.) having an output of 17.2 mW / cm 2 (the lamp is used for surface treatment (H-bulb)) to adjust the irradiation time by adjusting the irradiation time. It was.

UV irradiation amount of the ultraviolet ray-treated polarizing film was treated with 0.53 to 42.2mJ / ㎠.

The change of the surface contact angle of the polarizing film according to the ultraviolet irradiation treatment was measured in the same manner as described above, and the surface energy of the film was obtained therefrom. The results are shown in FIGS. 4 and 5, respectively.

From the results of Figure 4, it can be seen that the contact angle for diiodomethane and glycerin decreases with increasing UV irradiation dose and the contact angle of water increases. In addition, according to Figure 5, it can be seen that the surface energy (total surface energy) of the film decreases as the amount of ultraviolet irradiation increases. It can be seen that the reduction of the Lewis acidic acid base component affected the total surface energy reduction. 4 and 5 show that the film surface is hydrophobized by ultraviolet irradiation.

On the other hand, the transmittance and polarization efficiency of the surface-modified polarizing film by varying the amount of ultraviolet radiation was measured and the results are shown as FIG.

The specific measuring method of transmittance and polarization efficiency is as follows.

(1) Permeability

The transmittance of one film was measured using a UV-visible spectrophotometer (Agilent 845).

(2) polarization efficiency (PE)

The polarization efficiency at the maximum absorption wavelength was calculated based on the following equation.

In the above formula, PE represents the polarization efficiency, T _∥ indicates the transmittance when two sheets of polarizing film in parallel, T _를 indicates the transmittance when two sheets of polarizing film are placed vertically.

From the results of FIG. 12, the polarized film whose surface was modified according to the present invention had a transmittance of 34 to 50%, a polarization efficiency of 88 to 99.9% at 600 nm, and an ultraviolet ray irradiation amount of 2.12 J / cm 2 in particular. In the case of the film, it can be seen that the transmittance increases while maintaining excellent polarization efficiency.

Example 2

A polyvinyl alcohol film (manufactured by Nihon Kosei Co., Ltd.) having an average degree of polymerization of 1700 and a thickness of 100 μm was immersed at 50 ° C. for 2 minutes using Solophenyl Black FR manufactured by CIBA Specialty Chemical as a dichroic dye, followed by 40 ° C. boric acid bath ( After stretching at a concentration of 2% by weight), washed with pure water at 25 ℃ water and dried for 4 minutes at 60 ℃ to obtain a polarizing film (thickness 30㎛). The irradiated film was controlled by using an irradiator (UVO-cleaner, manufactured by Jelight Co., Ltd.) having an output of 17.2 mW / cm 2 (the lamp is used for surface treatment (H-bulb)) to adjust the irradiation time by adjusting the irradiation time. It was.

UV irradiation amount of the ultraviolet ray-treated polarizing film was treated with 0.53 to 42.2mJ / ㎠.

About the obtained polarizing film, the surface contact value and surface energy of the film were measured by the method similar to Example 1, and the result was shown as FIG. 6 and FIG.

From the results of FIG. 6, it can be seen that the contact angle for diiodomethane and glycerin decreases with increasing UV irradiation dose and the contact angle of water increases. In addition, according to Figure 7, it can be seen that the surface energy (total surface energy) of the film decreases as the amount of ultraviolet irradiation increases. It can be seen that the reduction of the Lewis acidic acid base component affected the total surface energy reduction. 6 and 7 show that the film surface is hydrophobized by ultraviolet irradiation.

On the other hand, the transmittance and polarization efficiency was measured in the same manner as in Example 1 for the surface-modified polarizing film by varying the UV irradiation amount is shown as the result as FIG.

According to the results of FIG. 12, in the case of a polarizing film dyed with a dichroic dye using surface modification through ultraviolet rays according to the present invention, the transmittance was 22 to 32% at 600 nm, and the polarization efficiency was 93 to 97%. In the case of the polarizing film treated with 2.12J / ㎠ it can be seen that the transmittance increases. This result is similar to the iodine adsorption polarizing film as in Example 1, it can be seen that the transmittance is increased when the surface is hydrophobized by ultraviolet irradiation of the polarizing film colored with iodine or dye.

Example 3

Irradiator having an output of 17.2 mW / cm 2 after immersing a polyvinyl alcohol film (manufactured by Nihon Kosei Co., Ltd.) having an average degree of polymerization of 1700 and a film thickness of 100 μm in an aqueous solution of iodine at 0.02 molar concentration for 2 minutes (UVO-cleaner, manufactured by Jelight) (The lamp is used for surface treatment (H-bulb)) to adjust the irradiation time by adjusting the irradiation time, UV irradiation treatment, stretching in a boric acid bath (concentration 2% by weight) of 40 ℃, washed with pure water at 25 ℃ Then, it dried for 4 minutes at 60 degreeC, and obtained the polarizing film (thickness 30micrometer).

UV irradiation amount of the ultraviolet ray-treated polarizing film was treated with 0.53 to 42.2mJ / ㎠.

About the obtained polarizing film, the surface contact value and surface energy of the film were measured by the method similar to Example 1, and the result was shown as FIG. 8 and FIG.

From the results of FIG. 8, it can be seen that the contact angle for diiodomethane and glycerin decreases with increasing UV irradiation dose and the contact angle of water increases. In addition, according to FIG. 9, it can be seen that the surface energy (total surface energy) of the film decreases as the amount of ultraviolet irradiation increases. It can be seen that the reduction of the Lewis acidic acid base component affected the total surface energy reduction. 8 and 9 show that the film surface is hydrophobized by ultraviolet irradiation.

On the other hand, the transmittance and polarization efficiency of the polarizing film surface-modified by varying the amount of ultraviolet radiation was measured in the same manner as in Example 1 and the results are shown as FIG.

From the results of FIG. 13, in the case of a polarizing film whose surface was modified after coloring with iodine and before stretching was carried out according to the present invention, the transmittance was 34 to 55% at 600 nm, and the polarization efficiency was 74 to 99.9%, in particular, the amount of ultraviolet radiation. It can be seen that the polarized film surface-treated at 2.12J / cm 2 increases transmittance while maintaining excellent polarization efficiency.

Example 4

A polyvinyl alcohol film (manufactured by Nihon Kosei Co., Ltd.) having an average degree of polymerization of 1700 and a film thickness of 100 μm was immersed at 50 ° C. for 2 minutes using Solophenyl Black FR manufactured by CIBA Specialty Chemical as a dichroic dye, and then outputted at 17.2 mW / cm 2. Using an irradiator (UVO-cleaner, manufactured by Jelight Co., Ltd.) (lamp is used for surface treatment (H-bulb)) to adjust the irradiation time by adjusting the irradiation amount and UV irradiation treatment of 40 ℃ boric acid bath (concentration 2% by weight) After stretching in water), washed with pure water at 25 ℃ water and dried for 4 minutes at 60 ℃ to obtain a polarizing film (thickness 30㎛).

UV irradiation amount of the ultraviolet ray-treated polarizing film was treated with 0.53 to 42.2mJ / ㎠.

About the obtained polarizing film, the surface contact value and surface energy of the film were measured by the method similar to Example 1, and the result was shown as FIG. 10 and FIG.

From the results of FIG. 10, it can be seen that the contact angle for diiodomethane and glycerin decreases with increasing UV irradiation dose and the contact angle of water increases. Also, according to FIG. 11, it can be seen that the surface energy (total surface energy) of the film decreases as the amount of ultraviolet irradiation increases. It can be seen that the reduction of the Lewis acidic acid base component affected the total surface energy reduction. 10 and 11 show that the surface of the film is hydrophobized by ultraviolet irradiation.

On the other hand, the transmittance and polarization efficiency of the polarizing film surface-modified by varying the amount of ultraviolet radiation was measured in the same manner as in Example 1 and the results are shown as FIG.

From the results of FIG. 13, in the case of a polarizing film dyed with a dichroic dye using surface modification through ultraviolet rays according to the present invention, the transmittance was 600 to 26.6%, the polarization efficiency was 93 to 97%, and the amount of ultraviolet radiation It can be seen that the transmittance is increased in the case of the polarizing film treated with 2.12J / cm 2. These results are similar to those of the iodine adsorption polarizing film as in Example 3 and similar to those of surface modification on the colored polarizing films of Examples 1 to 2 when the surface is hydrophobic regardless of the UV irradiation process sequence. It can be seen that it has an equivalent effect on the permeability.

As described in detail above, according to the present invention, the polarized film whose surface is modified by UV irradiation has excellent polarization efficiency and improves transmittance, and ultimately, does not inhibit the transmission of light generated from the backlight. In particular, it is possible to provide an economical and easy method for improving the transmittance even by a simple treatment of irradiating ultraviolet rays to the polarizing film, in which iodine adsorption or dye dyeing is completed.

Claims (9)

A polarizing film comprising iodine or a dichroic dye in a polyvinyl alcohol base film whose surface is modified by ultraviolet irradiation. The polarizing film of claim 1, wherein the polarization efficiency is 22 to 55% and the transmittance is 74 to 99.9%. The polarizing film of claim 1, wherein the polyvinyl alcohol base film is modified by irradiating ultraviolet rays in the presence of ozone. The polarizing film of claim 1 or 3, wherein the polyvinyl alcohol-based substrate film is irradiated with ultraviolet rays so as to have an ultraviolet irradiation amount of 0.53 to 42.4 J / cm 2. In the method of manufacturing a polarizing film, comprising adsorbing an iodine compound or dyeing a dichroic dye before uniaxial stretching of a polyvinyl alcohol-based film, or after dyeing, and fixing the divinyl dye in an aqueous solution of a crosslinking agent. A method for producing a polarizing film, characterized in that the step of modifying the surface of the film through ultraviolet irradiation after the adsorption of the iodine compound on the polyvinyl alcohol-based film or dyeing of the dichroic dye and before stretching. In the method of manufacturing a polarizing film, comprising adsorbing an iodine compound or dyeing a dichroic dye before uniaxial stretching of a polyvinyl alcohol-based film, or after dyeing, and fixing the divinyl dye in an aqueous solution of a crosslinking agent. A method for producing a polarizing film, characterized in that the step of modifying the film surface through ultraviolet irradiation after stretching while adsorbing the iodine compound on the polyvinyl alcohol-based film or dyeing the dichroic dye. In the method of manufacturing a polarizing film, comprising adsorbing an iodine compound or dyeing a dichroic dye before uniaxial stretching of a polyvinyl alcohol-based film, or after dyeing, and fixing the divinyl dye in an aqueous solution of a crosslinking agent. Method for producing a polarizing film, characterized in that to perform a step of modifying the film surface through ultraviolet irradiation after the fixing step. The method of manufacturing a polarizing film according to any one of claims 5 to 7, wherein the ultraviolet irradiation is performed so that the irradiation amount is 0.53 to 42.4 J / cm 2. The method of claim 5, wherein the ultraviolet irradiation is performed in the presence of ozone (O ₃ ).

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