KR102170460B1 - Manufacturing method for polarizing film and polarizing film manufactured by the same - Google Patents

Abstract

According to an embodiment of the present invention, the step of preparing an unstretched polyvinyl alcohol-based film; And there is provided a method of manufacturing a polarizing film comprising the step of stretching the unstretched polyvinyl alcohol-based film in a humidified atmosphere.

Description

A method of manufacturing a polarizing film and a polarizing film manufactured thereby TECHNICAL FIELD [0002]

The present invention relates to a method of manufacturing a polarizing film and a polarizing film manufactured thereby.

Optical functional films are widely used as components such as display devices. In particular, polarizing films can selectively pass only light that vibrates in one direction from among light that vibrates in all directions, so display devices such as liquid crystal displays. It is widely used in Moreover, since polarizing films can determine the passage and blocking of light when disposed in a pair, they are recently used as essential components of various display devices such as TVs, monitors, notebook computers, digital cameras, and mobile phones.

In such a display device, a polarizing film is necessarily used in order to exhibit optical characteristics, and a polyvinyl alcohol-based film adsorbed with iodine (I ₂ ) or a dichroic dye is generally used.

The polyvinyl alcohol-based film used for the polarizing film can be manufactured through several steps. The step of preparing the polyvinyl alcohol-based film may include a dyeing step, a crosslinking step, a stretching step, a washing step, a complementary color step, and a drying step. Among the above steps, the stretching step is for orienting the polymer chains of the polyvinyl alcohol-based film in a certain direction, and may be stretched by immersing in a stretching solution containing boric acid, potassium iodide, or the like.

Since the color rendering solution is prepared by adding a large amount of boric acid, potassium iodide, etc., the manufacturing cost of the polyvinyl alcohol-based film may be increased, and the drawing solution used for drawing a large number of polyvinyl alcohol-based films is waste-treated. In addition, additional costs and environmental pollution problems may occur.

Therefore, there is a need for a technology capable of easily manufacturing a polyvinyl alcohol-based film in an eco-friendly manner at low cost.

The present invention relates to a method of manufacturing a polarizing film and a polarizing film manufactured thereby.

According to an embodiment of the present invention, the step of preparing an unstretched polyvinyl alcohol-based film; And there is provided a method of manufacturing a polarizing film comprising the step of stretching the unstretched polyvinyl alcohol-based film in a humidified atmosphere.

According to another embodiment of the present invention, a polarizing film manufactured by a method of manufacturing a polarizing film according to an embodiment of the present invention is provided.

According to another embodiment of the present invention, a display unit including a display panel and the polarizing film, and including the polarizing film on at least one surface of the display panel is provided.

According to an embodiment of the present invention, by stretching the unstretched polyvinyl alcohol-based film in a humidified atmosphere, the amount of boric acid, potassium iodide, and the like can be reduced, thereby reducing the manufacturing cost of the polarizing film.

According to an embodiment of the present invention, by stretching the unstretched polyvinyl alcohol-based film in a humidified atmosphere without being immersed in the stretching liquid, waste treatment cost of the stretching liquid can be reduced, and environmental pollution can be reduced.

According to an embodiment of the present invention, a polyvinyl alcohol-based film having excellent optical properties can be easily manufactured.

1 is a diagram schematically illustrating stretching an unstretched polyvinyl alcohol-based film using two humidifying chambers according to an embodiment of the present invention.
2 is a diagram showing the single transmittance and orthogonal transmittance in the visible light region of the polyvinyl alcohol films prepared in Example 1 and Comparative Example 1 of the present invention.

When a part of the specification is said to "include" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated. In addition, in this specification, when a member is positioned "on" another member, this includes not only the case where a member is in contact with the other member, but also the case where another member exists between the two members.

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

According to an embodiment of the present invention, the step of preparing an unstretched polyvinyl alcohol-based film; And there is provided a method of manufacturing a polarizing film comprising the step of stretching the unstretched polyvinyl alcohol-based film in a humidified atmosphere.

According to an embodiment of the present invention, by stretching the unstretched polyvinyl alcohol-based film in a humidified atmosphere, the amount of boric acid, potassium iodide, and the like may be reduced, thereby reducing the manufacturing cost of the polarizing film.

Specifically, the manufacturing method of the polarizing film according to the present invention is not stretched by immersing the unstretched polyvinyl alcohol-based film in a stretching solution during the stretching process of the unstretched polyvinyl alcohol-based film, but the unstretched polyvinyl alcohol-based film in a humidified atmosphere. It is characterized in that the alcohol-based film is stretched.

In addition, according to an embodiment of the present invention, it is possible to reduce the occurrence of waste treatment costs and environmental pollution that may occur in the method of stretching an unstretched polyvinyl alcohol-based film by immersing an unstretched polyvinyl alcohol-based film in a conventional stretching solution.

According to an embodiment of the present invention, prior to the stretching step, the step of dyeing the unstretched polyvinyl alcohol-based film may be further included. Specifically, in the dyeing step, the unstretched polyvinyl alcohol-based film may be dyed with iodine molecules and/or a dichroic dye. As iodine molecules and/or dichroic dyes are dyed on the unstretched polyvinyl alcohol-based film, the unstretched polyvinyl alcohol-based film absorbs light vibrating in the stretching direction and allows light vibrating in the vertical direction to pass. It can have polarization properties with a specific vibration direction.

According to an embodiment of the present invention, in the dyeing step, the unstretched polyvinyl alcohol-based film may be immersed in a treatment bath containing an iodine solution and/or a dyeing solution containing a dichroic dye. The dyeing solution may contain a solvent, iodine and/or a dichroic dye. Water may be used as the solvent, and a mixture of water and an organic solvent having compatibility with water may be used. By controlling the concentration of iodine and/or dichroic dye in the dyeing solution, the transmittance of the polarizing film including the unstretched polyvinyl alcohol-based film can be controlled. Specifically, the dyeing solution may contain 0.06 parts by weight or more and 0.25 parts by weight or less of iodine and/or a dichroic dye based on 100 parts by weight of the solvent.

In addition, by adding an auxiliary agent such as an iodide compound to the dyeing solution, dyeing efficiency for the unstretched polyvinyl alcohol-based film can be improved. Iodine has low solubility in water, and by adding an auxiliary agent such as an iodide compound that can improve the solubility of iodine, the dyeing efficiency for the unstretched polyvinyl alcohol-based film can be improved. The iodide compound that can be used as the auxiliary may include at least one selected from the group consisting of potassium iodide, lithium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. I can.

According to an embodiment of the present invention, in order to dye the unstretched polyvinyl alcohol-based film, the unstretched polyvinyl alcohol-based film is immersed in a dyeing solution of 25° C. or more and 40° C. for 30 seconds or more and 120 seconds or less. I can. By controlling the temperature of the dyeing solution to 25° C. or more and 40° C. or less, dyeing efficiency can be improved, and iodine is prevented from sublimation, thereby reducing the amount of iodine used. In addition, by immersing the unstretched polyvinyl alcohol-based film in the dyeing solution for 30 seconds or more and 120 seconds or less, it is possible to uniformly dye the unstretched polyvinyl alcohol-based film.

According to an embodiment of the present invention, after dyeing the unstretched polyvinyl alcohol-based film, in order to remove the dyeing solution remaining in the unstretched polyvinyl alcohol-based film, the unstretched polyvinyl alcohol-based film is Can be washed. In order to clean the unstretched polyvinyl alcohol-based film, water or an aqueous boric acid solution may be used. Specifically, an aqueous boric acid solution having a boric acid concentration of 0.1 wt% or more and 2.5 wt% or less may be used.

According to an embodiment of the present invention, after the dyeing step, a step of crosslinking the unstretched polyvinyl alcohol-based film may be further included. By crosslinking the unstretched polyvinyl alcohol-based film, iodine and/or a dichroic dye may be adsorbed onto the polyvinyl alcohol polymer matrix of the unstretched polyvinyl alcohol-based film. The unstretched polyvinyl alcohol-based film may be crosslinked by immersing the unstretched polyvinyl alcohol-based film in a crosslinking solution containing a crosslinking agent or by applying or spraying a crosslinking solution containing a crosslinking agent.

According to an embodiment of the present invention, the crosslinking solution may include a solvent and a crosslinking agent. The crosslinking agent may be added in an amount of 0.5 parts by weight or more and 5 parts by weight or less based on 100 parts by weight of the solvent. By adjusting the content of the crosslinking agent within the above range, it is possible to prevent the stretchability of the unstretched polyvinyl alcohol-based film from deteriorating. As the crosslinking agent, boron compounds such as boric acid and borax, glyoxal, glutaraldehyde, and the like may be used.

According to an embodiment of the present invention, in the crosslinking step, the unstretched polyvinyl alcohol-based film may be immersed in a crosslinking solution of 25°C or more and 40°C or less for 30 seconds or more and 120 seconds or less. By adjusting the temperature of the crosslinking solution to 25° C. or more and 40° C. or less, the stretchability of the unstretched polyvinyl alcohol-based film can be improved. In addition, by immersing the unstretched polyvinyl alcohol-based film in the crosslinking solution for 30 seconds or more and 120 seconds or less, crosslinking may be uniformly formed in the unstretched polyvinyl alcohol-based film.

According to an embodiment of the present invention, the step of complementing the unstretched polyvinyl alcohol-based film may be further included. The complementary coloring step may be performed before the step of crosslinking the dyed and washed unstretched polyvinyl alcohol-based film, or may be performed after the step of crosslinking.

According to an embodiment of the present invention, in the step of complementing the color, the color of the unstretched polyvinyl alcohol-based film may be corrected. In order to correct the color of the unstretched polyvinyl alcohol-based film, the unstretched polyvinyl alcohol-based film may be immersed in a complementary color solution containing potassium iodide. As the complementary solution, a solution having a concentration of potassium iodide of 4.5% by weight or more and 6% by weight or less may be used.

According to an embodiment of the present invention, the unstretched polyvinyl alcohol-based film may be cleaned in order to remove the complementary color remaining in the complementary color of the unstretched polyvinyl alcohol-based film. However, when the complementary colored unstretched polyvinyl alcohol-based film is directly cleaned, the color correction effect of the complementary colored unstretched polyvinyl alcohol-based film may be reduced and optical characteristics may be deteriorated. It can be washed after drying the new polyvinyl alcohol-based film.

According to an embodiment of the present invention, the stretching step may be stretching the unstretched polyvinyl alcohol-based film in a humidified atmosphere. By stretching the unstretched polyvinyl alcohol-based film in a humidified atmosphere, the polymer chains of the unstretched polyvinyl alcohol-based film can be oriented in a certain direction.

In general, in order to stretch an unstretched polyvinyl alcohol-based film, a method of immersing in a stretching solution containing boric acid, potassium iodide, or the like is used. However, in the process of stretching a polyvinyl alcohol-based film in a long elongated form by continuously immersing it in a stretching solution, polyvinyl alcohol molecules having a low molecular weight escape from the polyvinyl alcohol-based film and may exist in the stretching liquid. Low molecular weight polyvinyl alcohol molecules present in the stretching solution may adhere to the surface of the polyvinyl alcohol-based film to be stretched later, and may precipitate as a foreign material and cause defects in the manufactured polarizing film. In addition, as the stretching solution is prepared by adding a large amount of boric acid, potassium iodide, etc., the manufacturing cost of the polyvinyl alcohol-based film may increase, and the cost of waste treatment of the stretching solution containing low molecular weight polyvinyl alcohol molecules is increased. There is an additional problem.

On the other hand, according to an embodiment of the present invention, by stretching the unstretched polyvinyl alcohol-based film in a humidified atmosphere, it is possible to reduce the manufacturing cost of a polyvinyl alcohol-based film, and to provide a polyvinyl alcohol-based film having excellent optical properties. Can be implemented. In addition, by not immersing the unstretched polyvinyl alcohol-based film in a stretching bath, it is possible to prevent the surface condition of the transferred polyvinyl alcohol-based film from deteriorating.

According to an embodiment of the present invention, the stretching may be performed at a humidity of 70 RH% or more and 100 RH% or less. By controlling the amount of water vapor supplied in the process of stretching the unstretched polyvinyl alcohol-based film, and stretching under a humidity condition of 70 RH% or more and 100 RH% or less, the polymer chain of the unstretched polyvinyl alcohol-based film is effectively Orientation can be performed, and running stability of the polyvinyl alcohol-based film can be ensured during the stretching process of the polyvinyl alcohol-based film.

According to an embodiment of the present invention, the stretching may be performed at a temperature of 40° C. or more and 70° C. or less. According to an embodiment of the present invention, water vapor having a temperature of 40° C. or more and 70° C. or less may be supplied to the unstretched polyvinyl alcohol-based film using a boiler, and air and water vapor passed through a heat exchanger may be mixed at 40° C. Water vapor having a temperature of not less than 70° C. can be supplied to the unstretched polyvinyl alcohol-based film.

According to an embodiment of the present invention, by stretching the unstretched polyvinyl alcohol-based film at a temperature of 40° C. or more and 70° C. or less, it is possible to prevent deterioration of the stretchability of the unstretched polyvinyl alcohol-based film. In addition, by improving the flexibility of the polyvinyl alcohol-based film, it is possible to secure the running stability of the polyvinyl alcohol-based film during the stretching process of the polyvinyl alcohol-based film.

According to an embodiment of the present invention, in the stretching step, the unstretched polyvinyl alcohol-based film may be stretched at a stretching ratio of 4.0 times or more and 7.0 times or less. Specifically, the unstretched polyvinyl alcohol-based film can be stretched at a draw ratio of 5.0 times or more and 6.0 times or less.

By stretching the unstretched polyvinyl alcohol-based film at a draw ratio of 4.0 to 7.0 times or less, the polymer chains of the unstretched polyvinyl alcohol-based film can be sufficiently oriented, and the polymer chains can be prevented from being cut. have.

1 is a diagram schematically illustrating stretching an unstretched polyvinyl alcohol-based film using two humidifying chambers according to an embodiment of the present invention. Referring to Figure 1, the elongated form of the unstretched polyvinyl alcohol-based film (F) is transferred from the first stretching roll 110 to the third stretching roll 130 along the longitudinal direction of the film in a humidified atmosphere and stretching Can be. In order to form a humidifying atmosphere in the unstretched polyvinyl alcohol-based film F, two humidifying chambers of the first humidifying chamber 210 and the second humidifying chamber 220 may be used.

According to an embodiment of the present invention, the stretching may be performed in two or more humidifying chambers having different temperatures and humidity. Physical properties of the unstretched polyvinyl alcohol-based film may be changed during the stretching process. Water vapor having an appropriate temperature and humidity may be supplied to the unstretched polyvinyl alcohol-based film whose physical properties are changed during the stretching process by using two or more humidifying chambers having different temperatures and humidity. In response to the changing physical properties of the unstretched polyvinyl alcohol-based film, water vapor having an appropriate temperature and humidity is separately supplied through two or more humidification chambers to prevent the deterioration of the stretchability of the unstretched polyvinyl alcohol-based film. And the polymer chain of the unstretched polyvinyl alcohol-based film can be effectively oriented.

According to an embodiment of the present invention, the stretching may include: a first humidification chamber of the unstretched polyvinyl alcohol-based film at a temperature of 40° C. or more and 60° C. and an atmosphere of 70 RH% or more and 100 RH% or less; And a second humidification chamber having a temperature of 50° C. or more and 70° C. or less and an atmosphere of 80 RH% or more and 100 RH% or less.

Specifically, the first humidification chamber may have a temperature of 40°C or more and 60°C or less and an atmosphere of 80 RH% or more and 100 RH% or less, and the first humidification chamber may have a temperature of 50°C or more and 60°C or less and 90 RH% It may be an atmosphere of more than 100 RH% or less.

In addition, the second humidification chamber may have a temperature of 50° C. or more and 70° C. or less and an atmosphere of 90 RH% or more and 100 RH% or less, and the second humidification chamber has a temperature of 60° C. or more and 70° C. or less and 90 RH% or more. It may be an atmosphere of 100 RH% or less.

Referring to FIG. 1, a first humidification chamber 210 may be provided between the first stretching roll 110 and the second stretching roll 120, and the second stretching roll 120 and the third stretching roll 130 ) A second humidification chamber 220 may be provided between. In a temperature of 40° C. or more and 60° C. or less and an atmosphere of 70 RH% or more and 100 RH% or less through the first humidification chamber 210, the unstretched polyvinyl alcohol-based film F is a first drawing roll 110 While being transferred to the second stretching roll 120 from, it may be stretched at a draw ratio of 3 times or more and 4.5 times or less. In addition, in a temperature of 50° C. or more and 70° C. or less and an atmosphere of 80 RH% or more and 100 RH% or less through the second humidification chamber 220, the polyvinyl alcohol-based film F is a second stretching roll 120 While being transferred to the third stretching roll 130 from, it may be finally stretched at a stretching ratio of 4.5 times or more and 7.0 times or less compared to the unstretched polyvinyl alcohol-based film supplied to the first stretching roll 110.

According to an embodiment of the present invention, by setting the temperature of the second humidifying chamber higher than the temperature of the first humidifying chamber, appropriate flexibility is provided to the stretched polyvinyl alcohol-based film, so that it is not immersed in pure water. Even in a state where the polymer chain of the polyvinyl alcohol-based film and the orientation of iodine are improved, a stretched polyvinyl alcohol-based film having excellent optical properties can be provided. In addition, it is possible to secure heat resistance and moisture-heat resistance of the polarizing film including the stretched polyvinyl alcohol film.

In addition, by setting the humidity of the second humidifying chamber higher than that of the first humidifying chamber, it is possible to secure the running stability of the polyvinyl alcohol-based film whose physical properties are changed during the stretching process.

According to an embodiment of the present invention, a temperature difference between the first humidifying chamber and the second humidifying chamber may be greater than 0° C. and less than or equal to 20° C., and the difference in humidity between the first humidifying chamber and the second humidifying chamber may exceed 0 RH% 30 It may be less than or equal to RH%.

Specifically, a temperature difference between the first humidifying chamber and the second humidifying chamber may be 2° C. or more and 10° C. or less. By setting the temperature difference between the first humidification chamber and the second humidification chamber to be more than 0 ℃ and not more than 20 ℃, it is possible to suppress the thermal shock of the polyvinyl alcohol-based film due to a rapid temperature difference, and the polyvinyl alcohol-based It is possible to prevent excessive crystallization of the polymer chain of the film.

In addition, a difference in humidity between the first humidification chamber and the second humidification chamber may be 5 RH% or more and 20 RH% or less, and 5 RH% or more and 10 RH% or less. By adjusting the difference in humidity between the first humidification chamber and the second humidification chamber to more than 0 RH% and less than 30 RH%, it is possible to prevent the stretchability of the polyvinyl alcohol-based film from deteriorating.

According to an embodiment of the present invention, the thickness of the unstretched polyvinyl alcohol-based film may be 10 μm or more and 70 μm or less. Specifically, the thickness of the unstretched polyvinyl alcohol-based film may be 15 μm or more and 60 μm or less. By using an unstretched polyvinyl alcohol-based film having a thickness of 10 µm or more and 70 µm or less, it is possible to prevent the durability of the polyvinyl alcohol-based film from deteriorating as the thickness of the film becomes thin during the stretching process.

According to another embodiment of the present invention, a polarizing film manufactured by a method of manufacturing a polarizing film according to an embodiment of the present invention is provided. The polarizing film may include a polyvinyl alcohol-based film stretched in a humidified atmosphere according to an embodiment of the present invention. By using the polyvinyl alcohol-based film stretched in the humidified atmosphere, a polarizing film having excellent optical properties can be implemented, and manufacturing cost of the polarizing film can be reduced.

According to another embodiment of the present invention, a polarizing plate including the polarizing film may be provided. The polarizing plate may include a protective film attached to at least one surface of the polarizing film. As a protective film attached to one or both sides of the polarizing film, an appropriate transparent film may be used. Specifically, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, etc. may be used. As the thermoplastic resin, cellulose resin such as triacetyl cellulose, polyester resin, polyethersulfone resin, polysulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, (meth)acrylic resin, cyclic Polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof may be used. However, the type of the thermoplastic resin described above is only an example for explanation, and does not limit the type of the thermoplastic resin.

According to another embodiment of the present invention, the polarizing plate may include a film having optical properties such as a retardation film, a visual compensation film, and a brightness enhancing film in addition to the polarizing film. In addition, a protective transparent film for protecting the surface may be attached to the polarizing plate. As the protective transparent film, for example, a triacetyl cellulose film, a polyethylene phthalate film, or the like may be used. On one side of the polarizing plate, an adhesive layer capable of attaching the polarizing plate to the panel may be formed, and a release film may be attached to the adhesive layer to protect the adhesive layer. The adhesive layer may be made of an acrylic adhesive, a silicone adhesive, or a urethane adhesive, and as a release film, a polyethylene terephthalate-based film, a polyolefin-based film, or the like may be used.

According to another embodiment of the present invention, a display unit including a display panel and the polarizing film, and including the polarizing film on at least one surface of the display panel is provided. By using a polarizing film including a polyvinyl alcohol-based film stretched in a humidified atmosphere, it is possible to overcome the problems that may occur in the method of stretching the existing polyvinyl alcohol-based film by immersing it in a stretching tank, thereby manufacturing a display unit. Cost and defects can be effectively reduced.

Hereinafter, examples will be described in detail to illustrate the present invention in detail. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention is not construed as being limited to the embodiments described below. The embodiments of the present specification are provided to more completely describe the present invention to those of ordinary skill in the art.

Unstretched Preparation of polyvinyl alcohol film

After swelling a polyvinyl alcohol (PVA) film (Japan Synthetic Company, M2004) 20 µm in a room temperature water bath for 60 seconds, 25 containing 3% by weight of a dichroic dye (iodine: potassium iodide = 1:30) A polyvinyl alcohol film was immersed for 60 seconds in a dyeing solution of not less than ℃ 30 ℃ dyeing treatment. After washing the dyed polyvinyl alcohol film with water, the polyvinyl alcohol film was immersed in a crosslinking solution containing 3% by weight of boric acid at 30° C. or higher and 45° C. for 60 seconds to perform crosslinking treatment. After the crosslinked polyvinyl alcohol film was washed with water, it was immersed in a complementary color solution having a potassium iodide concentration of 5% by weight to treat a complementary color. The complementary polyvinyl alcohol film was dried at 80° C. and washed to prepare an unstretched polyvinyl alcohol film.

Preparation of polyvinyl alcohol film

Example One

The prepared unstretched polyvinyl alcohol film was stretched 4.4 times in an atmosphere of 50° C. and 94 RH% through a first humidification chamber, and finally 5.4 times stretched in an atmosphere of 60° C. and 98 RH% through a second humidification chamber. The prepared polyvinyl alcohol film was prepared. Thereafter, the polyvinyl alcohol film was dried in an 80 oven for 3 minutes, and the dried polyvinyl alcohol film was washed with water for 1 second to prepare a final polyvinyl alcohol film.

Example 2

The prepared unstretched polyvinyl alcohol film was stretched 4.43 times in an atmosphere of 50° C. and 93 RH% through a first humidification chamber, and finally 5.4 times stretched in an atmosphere of 55° C. and 99 RH% through a second humidification chamber. Except for one, a polyvinyl alcohol film was prepared in the same manner as in Example 1.

Comparative example One

The prepared unstretched polyvinyl alcohol film was stretched 5.4 times while immersing the polyvinyl alcohol film in a stretching solution at 52° C. containing 1.5% by weight of boric acid for 60 seconds.

Comparative example 2

The prepared unstretched polyvinyl alcohol film was stretched 4.60 times in a non-humidified condition rather than a humidified atmosphere, and finally 5.4 times stretched in a non-humidified condition instead of a humidified atmosphere to prepare a polyvinyl alcohol film.

Optical properties Measure

After attaching the polyvinyl alcohol films prepared in Examples 1 to 2 and Comparative Examples 1 to 2 of the present invention to V-7100 SMPL JIG with a tape, using a spectrophotometer (JAS.CO, V-7100) to light The properties were measured.

Table 1 below shows the optical properties measurement experiment results of the polyvinyl alcohol films prepared in Examples 1 to 2 and Comparative Examples 1 to 2 of the present invention. In Table 1, Ts is the single transmittance of the polyvinyl alcohol film, Tp is the parallel transmittance of the polyvinyl alcohol film, Tc is the orthogonal transmittance of the polyvinyl alcohol film, and PE is the polarization degree of the polyvinyl alcohol film, a, b, orthogonal a, orthogonal b is the hunter lab color coordinate of the polyvinyl alcohol film, orthogonal 405 is the orthogonal transmittance of the polyvinyl alcohol film for light having a wavelength value of 405 nm, and orthogonal 440 is the polyvinyl alcohol film for light having a wavelength value of 440 nm. The orthogonal transmittance of the vinyl alcohol film, orthogonal to 700, is the orthogonal transmittance of the polyvinyl alcohol film to light having a wavelength value of 700 nm.

Comparative Example 1 Comparative Example 2 Example 1 Example 2 Ts 41.99 41.95 41.95 42.08 Tp 35.27 35.20 35.22 35.43 Tc 0.0011 0.0018 0.0006 0.0007 P.E 99.9969 99.9947 99.9982 99.9980 a -0.51 -0.69 -0.59 -0.58 b 2.04 2.03 2.67 2.63 Orthogonal a 0.56 1.14 0.19 0.19 Orthogonal b -0.91 -2.53 -0.18 -0.20 Orthogonal 405 0.055 0.105 0.013 0.016 Ortho 440 0.006 0.021 0.001 0.001 Orthogonal 700 0.016 0.007 0.005 0.006

Referring to Table 1, in a similar single transmittance (Ts), the polyvinyl alcohol films according to Examples 1 and 2 of the present invention have a higher polarization degree than the polyvinyl alcohol films according to Comparative Examples 1 and 2 ( PE).

FIG. 2 is a diagram showing the single transmittance and orthogonal transmittance in the visible light region of the polyvinyl alcohol films prepared in Example 1 and Comparative Example 1 of the present invention. In Figure 2, the x-axis represents the wavelength value of light irradiated to the polyvinyl alcohol film, the y-axis on the left is the single transmittance (Ts) of the polyvinyl alcohol film to the light irradiated to the polyvinyl alcohol film, and the y-axis on the right is poly It shows the orthogonal transmittance (Tc) of the polyvinyl alcohol film with respect to the light irradiated to the vinyl alcohol film.

2, the group transmittance and orthogonal transmittance of the polyvinyl alcohol film according to Example 1 of the present invention are similar to the group transmittance and orthogonal transmittance of the polyvinyl alcohol film according to Comparative Example 1. It can be seen that the polyvinyl alcohol film of the present invention has similar optical properties to the conventional polyvinyl alcohol film stretched by immersion in a stretching solution.

110: first drawing roll
120: second drawing roll
130: 3rd drawing roll
210: first humidification chamber
220: second humidification chamber

Claims (11)

Preparing an unstretched polyvinyl alcohol-based film; And
Including the step of stretching the unstretched polyvinyl alcohol-based film in a humidified atmosphere,
The stretching step is performed by sequentially passing through each of the first humidification chamber and the second humidification chamber having different temperatures and humidity,
The method of manufacturing a polarizing film, wherein the temperature of the second humidification chamber is higher than the temperature of the first humidification chamber. The method according to claim 1,
The stretching step is performed at a humidity of 70 RH% or more and 100 RH% or less. The method according to claim 1,
The stretching step is a method of manufacturing a polarizing film that is performed at a temperature of 40° C. or more and 70° C. The method according to claim 1,
The stretching step is to stretch the unstretched polyvinyl alcohol-based film at a stretching ratio of 4.0 times or more and 7.0 times or less. delete The method according to claim 1,
The stretching may include: a first humidification chamber of the unstretched polyvinyl alcohol-based film at a temperature of 40° C. or more and 60° C. or less and an atmosphere of 70 RH% or more and 100 RH% or less; And a second humidification chamber having a temperature of 50° C. or more and 70° C. or less and an atmosphere of 80 RH% or more and 100 RH% or less. The method of claim 6,
The method of manufacturing a polarizing film, wherein the temperature difference between the first humidification chamber and the second humidification chamber is greater than 0°C and less than or equal to 20°C. The method of claim 6,
The difference in humidity between the first humidification chamber and the second humidification chamber is greater than 0 RH% and less than or equal to 30 RH%. The method according to claim 1,
The thickness of the unstretched polyvinyl alcohol-based film is 10 μm or more and 70 μm or less. The method according to claim 1,
Prior to the stretching step, the method of manufacturing a polarizing film further comprising the step of dyeing the unstretched polyvinyl alcohol-based film. A polarizing film manufactured by the manufacturing method according to claim 1.

Images