KR100947936B1 - Method for manufacturing polarizer - Google Patents

Abstract

The present invention relates to a method of manufacturing a polarizer for use in thin film transistor liquid crystal display (TFT-LCD) for mobile, notebook, computer monitor and TV. The problem to be solved of the present invention is to optimize the swelling degree of the polarizing film substrate to facilitate the dyeing of the iodine compound into the polyvinyl alcohol during dyeing, thereby stabilizing optical properties such as polarization performance and at the same time It is to provide the manufacturing method of a polarizer excellent in the reliability of high quality, and the polarizing plate which avoid the wrinkle generation to the polarizing film base material in a line. The present invention is a manufacturing method of a polarizer, the polyvinyl alcohol (PVA) film of 40 to 75㎛ thickness of the base film of the polarizer as a pre-treatment step before the dyeing step swelling in a swelling tank containing a swelling liquid temperature of 15 to 35 ℃ However, the swelling solution is a swelling step using a boric acid solution containing boric acid 0.05 to 3.0% by weight; A dyeing step of dyeing the base film with iodine or dichroic dye; A crosslinking step of crosslinking the base film with a crosslinking agent; Drying step of drying the base film under a temperature of 40 to 60 ℃; At least one of the swelling step to the drying step is an invention comprising a stretching step of stretching the base film using a stretching roller.

According to the manufacturing method of the polarizer according to the present invention, by maximizing the dyeing efficiency by presenting the temperature range and the optimal compound of the dye solution in the dyeing process, the concentration, ultimately optimize the optical characteristics efficiency of the polarizer such as transmittance, polarization degree There is an advantage to obtain a polarizer and a polarizing plate.

Polarizer, polarizer, dyeing process, PVA film, temperature of dye solution, boron compound, boric acid

Description

Manufacturing method of polarizer {METHOD FOR MANUFACTURING POLARIZER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the fabrication of polarizers used in thin film transistor liquid crystal displays (TFT-LCDs) for mobiles, notebook computers, computer monitors, and televisions.

Polarizing plates are used inside and outside the liquid crystal cell for the purpose of controlling the vibration direction of light in order to visualize the display pattern of the liquid crystal display device. Generally used polarizing plate is a polyvinyl alcohol (PVA) resin film is dyed and uniaxially stretched by adsorption of a dichroic dye, the transparent resin film through one or both sides of the polarizer oriented the dichroic dye through an adhesive layer In particular, a cellulose acetate-based polarizer protective film represented by triacetyl cellulose (TAC) is laminated. This is bonded to the liquid crystal cell with an adhesive through another optical film as necessary to form a liquid crystal display device. Dichroic pigments include anthraquinones and azo dyes, as well as iodine.

In general, a method of manufacturing a polarizer is prepared by stretching a polyvinyl alcohol (PVA) film substrate, dyeing in an aqueous solution of iodine, drying through a color correction process using potassium iodine, or washing with water.

The manufactured polarizer is manufactured through a process of laminating a triacetate cellulose (TAC) film, which is a polarizer protective film, using a PVA-based adhesive.

During the manufacturing process, the swelling process is an important process for determining the optical characteristic efficiency of the polarizing plate. The process of swelling the polyvinyl alcohol film (swelling process), which is a preliminary step for dyeing the polyvinyl alcohol film, during the process of manufacturing the polarizer, makes the molecular chain of polyvinyl alcohol more flexible, and relaxes the molecular chain. In dyeing, an iodine compound or the like makes dyeing into the polyvinyl alcohol film easier.

However, in the swelling step of the polyvinyl alcohol film described above, when the degree of swelling of the film is left, it may be excessively swollen.

When the polyvinyl alcohol film is excessively swollen, wrinkles may occur in the manufacturing line on the resin film, and wrinkles may be present on the resin film surface, thereby impairing optical properties.

Furthermore, when wrinkles occur in the polyvinyl alcohol film in the manufacturing line, the film is bent and the running property of the film is deteriorated, resulting in uneven stretching, which may result in unstable quality.

The problem to be solved of the present invention is to stabilize the optical properties such as polarization performance by making the boric acid aqueous solution more easily dyed into the polyvinyl alcohol as the swelling liquid of the swelling tank to optimize the degree of swelling of the polarizing film substrate and At the same time, the present invention also provides a method for producing a polarizer excellent in high-quality reliability by avoiding wrinkles on the polarizing film substrate in the production line.

Method for producing a polarizer according to the present invention for solving the above problems is a polyvinyl alcohol (PVA) film of 40 to 75㎛ thickness of the polarizer base film as a pre-treatment step before the dyeing step, the temperature is 15 to 35 ℃ swelling liquid Swelling in the swelling tank containing the swelling, the swelling step is a swelling step using a boric acid solution containing 0.05 to 3.0% by weight of boric acid; A dyeing step of dyeing the base film with iodine or dichroic dye; A crosslinking step of crosslinking the base film with a crosslinking agent; Drying step of drying the base film under a temperature of 40 to 60 ℃; At least one of the swelling step to the drying step comprises the stretching step of stretching the base film using a stretching roller.

Herein, the polyvinyl alcohol film has a degree of polymerization of 1,500 to 3,000, which is preferable for the optical properties of the desired polarizer while serving as a polarizing substrate.

The present invention also provides a polarizing plate formed by laminating a polarizer protective film on at least one surface of a polarizer manufactured by the method using a polyvinyl alcohol-based adhesive.

In addition, the dyeing step is dyed by immersing the base film in an aqueous solution of iodine at a temperature of 20 to 40 ℃, the aqueous solution of iodine into the polyvinyl alcohol film using an aqueous solution of iodine containing 0.5 to 5% by weight of boric acid It facilitates the dyeing, prevents the cutting of the base film and the detachment of the iodine compound dyes on the base film to provide a polarizing plate excellent in optical properties.

In addition, the stretching step is made of a first stretching step and a second stretching step according to the change in the stretching magnification to perform the stretching, the stretching ratio of the base film in the first stretching step is 1.5 to 3.0 times, the second The stretching ratio of the base film in the stretching step is 2.0 to 3.0 times, and the total stretching ratio of the base film subjected to the polarizer manufacturing process is 5.0 to 8.0 times to suppress the occurrence of sagging or wrinkles of the base film and to prevent staining of the stretching. And cutting during stretching can be prevented.

According to the present invention, the degree of swelling of the polarizing film base material is optimized to make dyeing of iodine compounds into polyvinyl alcohol more easily during dyeing, thereby achieving stabilization of optical properties such as polarization performance and at the same time. By providing a method of manufacturing a polarizer having high quality and high reliability by avoiding wrinkles on the polarizing film substrate, there is an advantage in that a polarizer and a polarizing plate which ultimately optimize the optical characteristic efficiency of the polarizer such as transmittance and polarization degree can be obtained.

Hereinafter, the present invention will be described in detail.

1 is a front sectional view of a polarizing plate according to an embodiment of the present invention.

As shown in Figure 1, the polarizing plate according to an embodiment of the present invention forms a polarizer protective film 300 is laminated on both sides of the polarizer 100 via the adhesive 200.

Here, the polarizer 100 is made of a polyvinyl alcohol-based resin film, unlike in the embodiment, the polarizer protective film 300 may have a configuration formed on only one surface of the upper or lower side of the polarizer 100. have.

The polarizer 100 is manufactured by the manufacturing method mentioned later, The thickness is although it does not restrict | limit especially, Preferably it is 10-30 micrometers, More preferably, it is 10-20 micrometers.

The adhesive 200 is a material for adhering the polarizer 100 and the polarizer protective film 300, and an adhesive made of a vinyl alcohol-based polymer, or a vinyl alcohol-based adhesive such as boric acid or borax, glutaraldehyde, melamine, oxalic acid, or the like. A water-soluble crosslinking agent or the like of the polymer can be made alone or mixed. Such an adhesive is formed by the application drying layer of an aqueous solution, etc., and can add another additive, a catalyst, such as an acid, as needed. In particular, it is preferable to use an adhesive made of polyvinyl alcohol in that the adhesiveness with the PVA substrate for polarizer is the best.

The polarizer protective film 300 is a film attached to both upper and lower sides of the polarizer 100 to support and protect the polarizer, and a polymer having excellent transparency, mechanical strength, thermal stability, moisture shielding, or the like is preferably used. For example, an acetate resin such as triacetyl cellulose (TAC), a polyester resin, a polyether sulfone resin, a polycarbonate resin, a polyamide resin, a polyimide resin, a polyolefin resin, an acrylic resin, a polynor Borneen resin etc. are mentioned. In consideration of polarization characteristics, durability, and the like, most preferably, a triacetyl cellulose (TAC) film having a thickness of 80 µm or more obtained by saponifying a surface with alkali or the like is used.

Next, FIG. 2 is a flowchart sequentially showing a method of manufacturing a polarizer according to the present invention.

As shown in Figure 2, the manufacturing method of the polarizing plate according to the present invention comprises a swelling step (S10), dyeing step (S20), crosslinking step (S30), drying step (S40), stretching step (S50). .

Swelling step (S10) is more flexible to the molecular chain of the PVA in the PVA base film before performing the present process, including the dyeing step (S20), and relaxes the molecular chain to dye the PVA film such as iodine compounds in the dyeing process It is a process for facilitating dyeing to the inside, removing the plasticizer in the film, plasticizing the film and the like, and in the swelling step (S10) of the present invention, polyvinyl alcohol which is a base film of the polarizer 100. (PVA) film is performed by swelling in a swelling tank containing swelling liquid as a pretreatment step prior to the dyeing step (S20).

In the present invention, the polyvinyl alcohol film has a hydroxyl group (-OH) in its structure, so that it is more soluble in water than other polymers. Therefore, when PVA is added to water, it dissolves in hot water (75 ° C or higher) but is poorly soluble in cold water, and swells or dissolves in acid alkali. However, when the polyvinyl alcohol film is placed in an aqueous solution of boric acid, boric acid ions can be intercalated between hydroxyl groups of the polyvinyl alcohol film. Thus, when the polyvinyl alcohol and boric acid ions are combined, a long chain structure is formed. Therefore, the degree of swelling of the polarizing film substrate is optimized to make dyeing of iodine compounds into the polyvinyl alcohol more easily during dyeing, thereby achieving stabilization of optical properties such as polarization performance and at the same time. This can avoid the occurrence of wrinkles.

In the polyvinyl alcohol film which is a base film of the polarizer provided in the swelling step (S10) of the present invention, the degree of polymerization (DP) of polyvinyl alcohol is preferably 1,500 to 3,000. When the degree of polymerization of PVA used for the production of polarizer is less than 1,500, it is not sufficient to function as a polarizing substrate, and when the degree of polymerization is greater than 3,000, there is a fear that the optical properties of the polarizer desired in the present invention may be deteriorated.

In addition, the polyvinyl alcohol film is usually a thickness of 100㎛ or less is applied, preferably a film of 40 to 75㎛, more preferably 45 to 60㎛ thickness. When the thickness of the base film exceeds 75 μm, not only the dyeing efficiency is lowered, but when the manufactured polarizer is mounted on the liquid crystal display, there is a fear that the color change of the display panel may increase, and the thickness thereof is less than 40 μm. In this case, there is a problem that it is not easy to perform the stretching step (S50). However, in the case of using the base film having a thin thickness of 40 to 75㎛ high swelling degree of the base film in the swelling step (S10) has a high probability of occurrence of wrinkles, moisture in the process of performing the drying step (S40) Since evaporation is large and brittleness becomes large, since there is a high possibility that a crack will arise in the process of laminating with a polarizer protective film after manufacture of a polarizer, it is preferable to select an appropriate base film according to process conditions.

The swelling liquid used in the swelling step (S10) is preferably made of at least one of a boron compound consisting of pure water or preferably a boric acid aqueous solution, the temperature is 20 to 20 when using a polarizer base film having a thickness of 75㎛ or more It is preferable that it is 45 degreeC, More preferably, it is 25-35 degreeC, and when using the polarizer base film whose thickness is 75 micrometers or less, it is 15-35 degreeC, Preferably it is 18-30 degreeC, More preferably, it is 20-25 ℃.

Here, the temperature of 15 to 40 ℃ of the swelling liquid in the case of using a thin substrate film having a thickness of 75㎛ or less is set in order to suppress the occurrence of wrinkles in the base film by appropriately reducing the degree of swelling in performing the stretching step (S20) Is the optimal temperature condition. The swelling of the polyvinyl alcohol tends to be insufficient at less than 15 ° C, and swelling stains occur on the inner surface, so that the staining is easy to occur. On the other hand, at 40 ° C or higher, the swelling becomes high, causing swelling staining on the inner surface, or partially the polyvinyl alcohol. This is because dissolution occurs and staining is easy.

Here, when using boric acid aqueous solution as said swelling liquid, it is preferable to make the concentration of boric acid into the said swelling liquid 0.01 to 5 weight% based on 100 weight% of swelling liquid. When the concentration of boric acid in the swelling liquid exceeds 5% by weight, a decrease in polarization characteristics is considered. This is due to insufficient swelling of the film in proportion to increasing the boric acid concentration, and inferior dyeability due to a decrease in the degree of swelling of the film. In addition, since the surface crosslinking of the polyvinyl alcohol film is performed, dyeing of the dye solution into the base film is not easily performed during the dyeing process, and the problem may occur that the base film is cut in the stretching step (S50), and 0.01 wt% If less, it is impossible to ensure the running property of the film in the production line. In other words, the film is bent on the production line and wrinkles are caused on the film surface. This is due to the shrinkage of the film because the liquid temperature of the fixing bath is lower than the liquid temperature of the stretching (extension, extension) bath, and the balance of tension in the width direction of the film due to wrinkles.

In the swelling process, problems such as swelling of the film in the width direction and wrinkles of the film are likely to occur, so that an expander roll, a spiral roll, a crown roll, a cross guider ( It is preferable to convey a film, removing a wrinkle of a film with a well-known widening apparatus, such as a cross guider, a bend bar, a tenter crip, and the like. In order to stabilize the conveyance of the film in the bath, the water flow in the swelling bath is controlled by an underwater shower, or an EPC device (Edge Position Control device: a device which detects the end of the film and prevents meandering of the film) may be used in combination. useful. In this process, since a film swells and expands also in the traveling direction of a film, in order to remove the looseness of the film of a conveyance direction, it is preferable to take means, such as controlling the speed of the conveyance roll before and behind a processing tank.

The dyeing step (S20) is a process of adsorbing the dye inside the base film by immersing the base film in iodine or dichroic dye. Here, in the case of using an aqueous solution of iodine as a dye, a mixed aqueous solution containing iodine ions may be used by using a solution of potassium iodide in iodine as a dissolution aid, and the use concentration of the iodine is preferably 0.01 to 1% by weight, more preferably. Preferably it is 0.02 to 0.8 weight%, and the use concentration of the said potassium iodide is 0.01 to 10 weight%, More preferably, it is 0.05 to 8 weight%.

In addition to the iodine and potassium iodide, boric acid used in a crosslinking process may be further added to the aqueous solution of iodine used in the method of manufacturing a polarizer according to the present invention. The most excellent light is when the concentration of boric acid contained in the aqueous solution of iodine is 0.5 to 5.0% by weight, more preferably 1.0 to 3.5% by weight, particularly preferably 1.5 to 3.0% by weight, relative to 100% by weight of iodine solution. It can be seen that the characteristics.

When the addition concentration of the boric acid exceeds 5.0% by weight, the phenomenon that the dyeing into the inside of the PVA film is not easy due to the surface crosslinking of the PVA film, which is the base film, and when the concentration is less than 0.5% by weight, the stretching occurs. In step (S50), cutting of the base film and detachment of the iodine compound dyed into the base film are likely to occur, which causes a problem of deterioration of optical properties.

In addition, it is preferable that the temperature range of the iodine aqueous solution used as the said dyeing solution is 20-40 degreeC, More preferably, it is 25-35 degreeC. If the temperature of the dyeing solution exceeds 40 ℃ there is a problem that wrinkles in the base film, if the temperature is less than 20 ℃ problem that does not easily relax the PVA molecular chains, it is not easy to dye the inside of the PVA There is this.

The crosslinking step (S30) is a step performed to crosslink the PVA molecular chain of the base film by depositing the base film on a crosslinking agent. The crosslinking agent used preferably uses boric acid or borax solution. The boric acid aqueous solution may include potassium iodide.

Drying step (S40) is to dry the base film at 45 to 70 ℃, preferably 60 to 65 ℃ temperature, 40 to 60 ℃, preferably 55 to 60 ℃ temperature when using a substrate film of less than 75㎛ It's a step.

 The stretching step S50 may be performed together with at least one of the swelling step S10 and the drying step S40, before or after the beginning of at least one of the steps, or each step. You can also do it in between.

 Although the stretching method used in the stretching step (S50) is not particularly limited, both wet stretching method and dry stretching method can be used. The stretching method by the dry stretching method includes, for example, an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. Can be performed.

 The stretching step S50 may be performed together with at least one of the swelling step S10 and the drying step S40, before or after the beginning of at least one of the steps, or each step. You can also do it in between.

 Although the stretching method used in the stretching step (S50) is not particularly limited, both wet stretching method and dry stretching method can be used. The stretching method by the dry stretching method includes, for example, an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. Can be performed.

Stretching step (S50) according to the present invention consists of two stages of stretching in the first stretching step (S51), the second stretching step (S52), the first stretching step (S51) and the second stretching step (S52). Dividing the stretching step (S50) into is divided according to the change in the stretching ratio to perform the stretching. Performing the two-stage stretching is because a stable continuous production is possible, and as a result, it is advantageous to increase the overall draw ratio, which helps to improve the optical properties.

Here, the stretching ratio of the base film in the first stretching step (S51) is 1.5 to 3.0 times, the stretching ratio of the base film in the second stretching step (S52) is 2.0 to 3.0 times, the polarizer manufacturing process The stretching step (S50) is performed so that the total stretching ratio of the rough base film is 5.0 to 8.0 times.

Performing the stretching ratio in the first stretching step (S51) at 1.5 to 3.0 times is to reduce the risk of sagging or wrinkles of the base film due to the dyeing treatment, and to eliminate the staining of the stretching. If the draw ratio is less than 1.5 times, there is a problem that the film is stretched and the portion is dyed when dyed, when the stretch ratio exceeds 3.0 times, there is a problem that it is difficult to obtain a high transmittance, high polarization polarizing plate.

When the draw ratio in the second stretching step (S52) is 2.0 to 3.0 times, a problem of sagging or wrinkles of the base film occurs when less than 2.0 times, and when it exceeds 3.0 times, cutting of the film during stretching occurs. This is because there is a problem that occurs.

The polarizer 100 is manufactured through the polarizer manufacturing process (S100) and the lamination process (S200) of laminating with the polarizer protective film 300 described above.

   The method of adhering the polarizer 100 and the polarizer protective film 300 is not particularly limited, but is divided into a top-down method, a down-top method, and a horizontal lamination method. In the present invention, all three methods can be used.

When the polarizer protective film 300 is adhered to the polarizer 100, the adhesive may be applied by applying an adhesive in advance, or the adhesive may be adhered by dropping the adhesive when the polarizer 100 and the polarizer protective film 300 are laminated. have. In the present invention, it is possible to select one of the methods of applying the adhesive by applying an adhesive, dropping the adhesive, or both may be used together.

  An optical member such as another optical layer may be applied to the polarizing plate manufactured by the manufacturing method. The optical member is not particularly limited, but for example, a reflecting plate, a semi-transmissive reflecting plate, a retardation plate (including λ plates such as a 1/2 wave plate and a quarter wave plate), a visual compensation film, and a brightness enhancement film Etc. One or two or more layers of suitable optical layers that can be used for forming a liquid crystal display device or the like can be used.

Hereinafter, the present invention will be described in more detail with reference to examples of the present invention and comparative examples compared with the present invention.

Example  One

As a base film, a 75 μm-thick PVA film is a swelling tank containing a boric acid aqueous solution having a boric acid concentration of 0.5% by weight at 25 ° C., a dye bath containing a mixed aqueous solution of iodine and potassium iodide at a temperature of 30 ° C., and a 50 ° C. aqueous solution of boric acid. After uniaxially stretching in a tank and drawing at a draw ratio of 2.70 times, uniaxially stretching the base film while immersing in a drawing tank containing an aqueous solution of boric acid, drawing at a draw ratio of 2.33 times, and stretching at a total draw ratio of 6.3 times, and then at 55 ° C. Drying to prepare a polarizer. After preparing the polarizer, a polarizing plate was manufactured by laminating a tetraacetate cellulose (TAC) film, which is a polarizer protective film, with a polarizer.

Example  2

The polarizing plate was manufactured by the same manufacturing method as Example 1 except that 1.0% by weight of boric acid was contained in the aqueous solution of boric acid contained in the swelling tank and the temperature was 25 ° C.

Example  3

The polarizing plate was manufactured by the same manufacturing method as Example 1 except that 2.0 weight% of boric acid is contained in the aqueous solution of boric acid contained in a swelling tank, and the temperature is 25 degreeC.

Example  4

The polarizing plate was manufactured by the same manufacturing method as Example 1 except that 1.0% by weight of boric acid was contained in the aqueous solution of boric acid contained in the swelling tank and the temperature was 30 ° C.

Example  5

The polarizing plate was manufactured by the same manufacturing method as Example 1 except that the boric acid solution contained in the swelling tank contained 2.0 wt% of boric acid and the temperature was 30 ° C.

Example 6

The polarizing plate was manufactured by the same manufacturing method as Example 1 except that 2.0 weight% of boric acid is contained in the aqueous solution of boric acid contained in a swelling tank, and the temperature is 35 degreeC.

Example  7

The polarizing plate was manufactured by the same manufacturing method as Example 1 except that the boric acid solution contained in the swelling tank contained 3.0 wt% of boric acid and the temperature was 35 ° C.

Comparative example  One

The polarizing plate was manufactured by the same manufacturing method as Example 1 except that the boric acid solution contained in the swelling tank contained 3.5 weight% of boric acid, and the temperature was 25 degreeC.

Comparative example  2

A polarizing plate was manufactured by the same method as in Example 1, except that boric acid was not included in the aqueous solution contained in the swelling tank and the temperature was 35 ° C.

For the evaluation of the characteristics of the polarizing plates manufactured by the Examples and Comparative Examples, the following experiment was performed.

The instrument (spectrophotometer) used Jasco's V-7100 model.

Transmittance and polarization degree

Transmittance = (I _out / I _in ) * 100 (%)

Where I _in : incident light and I _out : transmitted light

Group transmittance ( Ts )

Total light transmittance (%) of one polarizing plate.

Parallel transmittance ( TP )

Total light transmittance (%) when the polarizing axes of two polarizing plates are parallel and overlapping.

Orthogonal Transmittance ( Tc )

Total light transmittance (%) when the polarizing axes of two polarizing plates are orthogonal and overlap.

Polarization degree ( PE )

Polarization degree was calculated | required using the following formula.

Polarization degree (%) = [(Y ₀ -Y ₉₀ ) / (Y ₀ + Y ₉₀ )] ^1/2 ＊ 100

Y ₀ : Total light transmittance when the polarizing axes of two polarizing plates are arranged in parallel

Y ₉₀ : Total light transmittance when the polarizing axes of two polarizing plates are orthogonal to each other and overlapped.

Polarizer CR

Polarizing plate CR was calculated | required using the formula of parallel transmittance (Tp) / orthogonal transmittance (Tc).

The characteristic evaluation data is summarized in Table 1 below.

Remarks Group Transmittance (Ts) (%) Parallel transmittance (Tp) (%) Orthogonal Transmittance (Tc) (%) Polarization degree (PE) (%) Appearance and PVA Cutting Comparative Example 1 25 ℃ / 3.5% by weight - - - - PVA Cutting at Stretch Comparative Example 2 37.5 ° C / 0.0% by weight - - - - Wrinkles Example 1 25 ℃ / 0.5% by weight 43.27 37.36 0.013 99.965 Good Example 2 25 ℃ / 1.0% by weight 43.45 37.49 0.018 99.952 Good Example 3 25 ℃ / 2.0% by weight 43.38 37.41 0.023 99.939 Good Example 4 30 ℃ / 1.0% by weight 43.34 37.40 0.027 99.928 Good Example 5 30 ℃ / 2.0% by weight 43.42 37.44 0.028 99.925 Good Example 6 35 ℃ / 2.0% by weight 43.21 37.33 0.025 99.933 Good Example 7 35 ℃ / 3.0% by weight 43.49 37.52 0.029 99.923 Good

Table 1 shows the experimental results for Examples 1 to 7 and Comparative Examples 1 and 2.

 In Comparative Examples 1 and 2, problems that may occur during processing of the polarizer have been found. That is, the PVA cutting phenomenon at the time of extending | stretching, the film twisted the manufacturing line shape, and the phenomenon which wrinkles generate | occur | produced on the film surface generate | occur | produced.

However, as shown in Table 1, it can be seen that the polarizers prepared in all of Examples 1 to 7 exhibited excellent optical properties. Among them, the polarizing plate optical characteristics efficiency was the highest when the concentration of boric acid was 0.5% by weight at a temperature of 25 ° C in the case of Example 1. Nevertheless, there was no phenomenon in which the optical properties were impaired due to the occurrence of wrinkles in the manufacturing line or the presence of wrinkles on the resin film surface.

That is, wrinkles do not occur when the temperature and the concentration of the swelling liquid are within the numerical limits, or cutting of the polyvinyl alcohol film during stretching does not occur. In the case of the same boric acid concentration, the optical characteristic efficiency was the highest when the liquid temperature is 25 to 35 ℃.

As a result, in the swelling process conditions, it was found that the polarizing plate with high optical efficiency can be manufactured by adjusting the temperature of the swelling liquid, the addition of the boron compound, and the concentration to which the boron compound is added. That is, by optimizing the degree of swelling of the polyvinyl alcohol film to make dyeing of iodine compounds into the polyvinyl alcohol more easily during dyeing, the optical properties such as polarization performance can be stabilized, and the polarizing film substrate in the production line By providing a method of manufacturing a polarizer having high quality and excellent reliability by avoiding wrinkles, it is possible to manufacture a polarizer that ultimately optimizes optical characteristic efficiency of the polarizer such as transmittance and polarization degree.

In the above, this invention was demonstrated in detail with reference to an Example and a comparative example centering on a structure. However, the scope of the present invention is not limited to the above embodiments but may be embodied in various forms of embodiments within the appended claims. Without departing from the gist of the invention as claimed in the claims, any person of ordinary skill in the art is considered to be within the scope of the claims described in the present invention to the extent possible to vary.

1 is a front cross-sectional view of a polarizing plate according to an embodiment of the present invention.

2 is a flow chart sequentially showing the manufacturing method of the polarizer according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100: polarizer 200: adhesive 300: polarizer protective film

Claims (5)

In the manufacturing method of a polarizer, A polyvinyl alcohol (PVA) film having a degree of polymerization of 1,500 to 3,000 having a thickness of 40 to 75 μm, which is a base film of a polarizer, is swelled in a swelling tank containing a swelling liquid having a temperature of 25 to 35 ° C. as a pretreatment step before the dyeing step, The solution is a swelling step using an aqueous boric acid solution containing 0.01 to 5.0% by weight of boric acid; A dyeing step of dyeing the base film with iodine or dichroic dye; A crosslinking step of crosslinking the base film by at least one of boric acid or boric acid aqueous solution containing potassium iodide; Drying step of drying the base film under a temperature of 40 to 60 ℃; Stretching step of stretching the base film using a stretching roller; comprising, the dyeing step is dyed by immersing the base film in an aqueous solution of iodine at a temperature of 20 to 40 ℃, the aqueous solution of iodine is 1.5 to boric acid Method for producing a polarizer, characterized in that using an aqueous solution of iodine 3% by weight. delete delete The method of claim 1, The drawing step is made of a first drawing step and a second drawing step according to the change in the drawing magnification to perform the drawing, The stretching ratio of the base film in the first stretching step is 1.5 to 3.0 times, The stretching ratio of the base film in the second stretching step is 2.0 to 3.0 times, The total stretch ratio of the base film through the polarizer manufacturing process is 5.0 to 8.0 times the manufacturing method of the polarizer. delete

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