KR20200022092A - Mask film and method for preparing polarizing plate using same - Google Patents

Abstract

The present invention relates to a mask film used in the production of a polarizing plate having a local bleaching region and a polarizing plate produced using the same. The mask film comprises: a protective film; and an adhesive layer provided on one surface of the protective film.

Description

Mask film and manufacturing method of polarizing plate using same {MASK FILM AND METHOD FOR PREPARING POLARIZING PLATE USING SAME}

The present invention relates to a mask film used for producing a polarizing plate having a localized discoloration region through a chemical treatment, and a method of manufacturing a polarizing plate using the same.

Polarizers have been applied to various display devices such as liquid crystal displays and organic light emitting devices. Currently used polarizing plates are dyed iodine and / or dichroic dye on a polyvinyl alcohol (hereinafter, referred to as PVA) -based film, crosslinking the iodine and / or dichroic dye using boric acid, etc. It is used in the form of a protective film laminated on one side or both sides of the PVA polarizer produced by orientation by the method.

On the other hand, recently, display devices are becoming more and more slim, and in order to realize a large screen, the display device has been developed to minimize the thickness of bezels and edges on which a screen is not displayed. In addition, in order to implement various functions, components such as a camera are mounted on a display device, and in consideration of design elements, attempts have been made to assign or discolor various colors to a product logo or a border area.

However, in the case of the conventional polarizing plate, the polarizing plate is dark black because it is dyed with iodine and / or dichroic dye in the entire area of the polarizing plate, and as a result, it is difficult to impart various colors to the display device, and in particular, the polarizing plate on a component such as a camera In this case, the polarizing plate absorbs more than 50% of the amount of light, thereby deteriorating the visibility of the camera lens.

In order to solve such a problem, a method of physically removing a polarizing plate of a portion covering a camera lens by punching a hole (perforation) in a part of the polarizing plate by punching and cutting has been commercialized.

However, the above physical method degrades the appearance of the image display apparatus and may damage the polarizing plate due to the nature of the punching process. On the other hand, in order to prevent damage such as tearing of the polarizing plate, the perforated portion of the polarizing plate should be formed in an area sufficiently far from the corner. As a result, when the polarizing plate is applied, the bezel portion of the image display device becomes relatively wider. NARROW BEZEL's narrow bezel design trend is also a problem. In addition, when the camera module is mounted on the perforated portion of the polarizer as described above, the camera lens is exposed to the outside, so there is a problem in that contamination and damage of the camera lens are likely to occur when used for a long time.

Korean Unexamined Patent Publication No. 10-2006-0009837

The present invention is to solve the above problems, by providing a mask film used in the production of a polarizing plate having a localized discoloration area through a chemical treatment, as in the prior art, it is possible to remove the polarization without physically punctured, polarized light By minimizing wrinkles in these removed areas, it is intended to provide a polarizing plate having excellent surface roughness and haze.

The present invention is to provide a mask film used in the production of a polarizing plate having a localized discoloration region through a chemical treatment with excellent process efficiency, a manufacturing method of a polarizing plate using the same and a polarizing plate thereby.

One embodiment of the present invention, the protective film; And a pressure-sensitive adhesive layer provided on one surface of the protective film, wherein the pressure-sensitive adhesive layer has a pressure of 2 kgf / in to 100 kgf / in, and provides a mask film having a perforated part integrally passing through the protective film and the pressure-sensitive adhesive layer. .

Another embodiment of the invention, the step of laminating the mask film on one surface of the polarizer; Decolorizing a portion corresponding to the perforated portion of the mask film; And it provides a method of manufacturing a polarizing plate having a non-polarization portion comprising the step of removing the mask film.

In addition, there is provided a polarizing plate having a non-polarization part manufactured according to the method for producing a polarizing plate of the present invention.

In another aspect, the present invention provides an image display device including the polarizing plate described above.

In the mask film of the present invention, by adjusting the thickness of the pressure-sensitive adhesive, it is possible to improve the accuracy of the perforation, to prevent the phenomenon of the pressure-sensitive adhesive flow out, by laminating the mask film on at least one surface of the polarizer having iodine or dichroic dye By the decoloring treatment, there is an advantage that the process efficiency is excellent.

The mask film according to an embodiment of the present invention is to control the adhesive force of the pressure-sensitive adhesive layer within a specific range, to suppress the generation of bubbles when forming the perforations in the mask film, from the polarizer during the roll-to-roll process (roll to roll process) By easily removing the pressure-sensitive adhesive and decolorizing the mask film by laminating at least one surface of the polarizer having iodine or dichroic dye, it is possible to decolorize only a desired portion, thereby providing excellent process efficiency.

1 illustrates a mask film composed of a protective film and an adhesive layer according to an exemplary embodiment of the present invention.
Figure 2 illustrates a mask film composed of a protective film, an adhesive layer and a release film according to an embodiment of the present invention.
Figure 3 illustrates a polarizing plate manufacturing method according to an embodiment of the present invention.
Figure 4 schematically shows a method of measuring the edge roughness (Edge Roughness) according to an embodiment of the present invention.
5 is a view illustrating bubble generation portions generated in the discoloration portion of the polarizing plate.

Hereinafter, preferred embodiments of the present invention will be described. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

Mask film according to an embodiment of the present invention, the protective film; It has an adhesive layer provided on one surface of the protective film, the adhesive force of the pressure-sensitive adhesive layer is 2kgf / in to 100kgf / in, and has a perforated part through the protective film and the pressure-sensitive adhesive layer integrally.

In the present specification, the adhesive force of the pressure-sensitive adhesive layer is 2kgf / in to 100kgf / in, more preferably 10kgf / in to 50kgf / in. When the adhesive force of an adhesive layer is the said range, the accuracy of decolorization becomes high and peeling of a mask film is easy. When the adhesive force is less than 2kgf / in, the mask film is laminated on the polarizer, bubbles may be generated in the perforated area during the roll to roll process, and the discoloration part may be damaged. When the adhesive force is greater than 100 kgf / in, the removal of the mask film is It is difficult to have a problem that the adhesive is buried in the polarizer. In addition, after the release film is removed in order to laminate the mask film on one side of the polarizer, the presence of a perforation part causes an interface in the middle of the plane. If the modulus is not within the above range, the adhesive may be damaged at the perimeter of the perforation part. , The problem that the adhesive is transferred to the release film rather than the mask film may occur.

The adhesive force of the pressure-sensitive adhesive in the present invention is measured by peeling 180 times at a speed of 5mm / sec using a TA Texture Analyzer after reciprocating five times at a speed of 300mm / min with a 2kg roll in accordance with JIS Z 0237.

In one embodiment of the present invention, the mask film may further have a release film attached to the pressure-sensitive adhesive layer, the release film is removable from the pressure-sensitive adhesive layer.

In one embodiment of the present invention, two or more of the perforations are disposed at predetermined intervals in the longitudinal direction of the mask film.

In one embodiment of the present invention, two or more of the perforations are disposed at equal intervals in at least the longitudinal direction of the mask film.

In one embodiment of the present invention, two or more of the perforations are disposed at equal intervals in the longitudinal direction of the mask film and the width direction of the mask film.

1 illustrates a mask film composed of a protective film and an adhesive layer according to an exemplary embodiment of the present invention.

Figure 2 illustrates a mask film composed of a protective film, pressure-sensitive adhesive layer and a release film according to an embodiment of the present invention.

In FIG. 1 and FIG. 2, the relatively dark areas mean perforations penetrating the mask film.

According to another embodiment of the present invention, the mask film may have a perforation part through the protective film, the pressure-sensitive adhesive layer and the release film integrally.

The forming of the perforations in the mask film is not particularly limited, and may be performed through film perforation methods well known in the art, for example, mold processing, knife processing, or laser processing.

According to an exemplary embodiment of the present invention, the forming of the perforation part may be performed through laser processing. The laser processing may be performed using laser processing apparatuses generally known in the art, and are not particularly limited. Laser processing conditions such as the type of laser device, output power, laser pulse repetition rate, etc. may vary depending on the material, thickness of the film, and the shape of the perforated part, and those skilled in the art may appropriately determine the laser processing conditions in consideration of the above points. You can choose to. For example, when using a polyolefin film having a thickness of 30 μm to 100 μm as a mask film, a carbon dioxide (CO ₂ ) laser device having a center wavelength of about 9 μm to 11 μm or ultraviolet rays having a center wavelength of about 300 nm to 400 nm ( UV) device may be used to form perforations, where the maximum average power of the laser device may be about 0.1W to about 30W, and the pulse repetition rate may be about 0kHz to about 50kHz, but is not limited thereto.

Protective film of the mask film of the present invention, Polyethylene (Poly Ethylene, PE), Polypropylene (Poly Propylene, PP), Polyethylene terephthalate (Poly Ethylene Terephtalate, PET) and the like; Or a vinyl acetate-based film such as ethylene vinyl acetate (Ethylene Vinyl Acetate, EVA), poly vinyl acetate (Poly Vinyl Acetate) may be used, but is not limited thereto. In addition, the thickness of the mask film is not limited thereto, but may be about 10 μm to about 100 μm, preferably about 10 μm to about 70 μm.

The mask film of the present invention may be used to form a localized discoloration portion by laminating the mask film on at least one surface of the polarizer and then processing a portion corresponding to the perforation portion.

The local bleaching area of the present invention may be a polarization canceling area.

The stacking of the mask film on one surface of the polarizer may be performed by laminating methods of a film well known in the art, for example, attaching a mask film and a polarizing member through an adhesive layer. The pressure-sensitive adhesive layer may be an adhesive such as an acrylic pressure sensitive adhesive, a silicone pressure sensitive adhesive, an epoxy pressure sensitive adhesive, or a rubber pressure sensitive adhesive, but is not limited thereto.

According to an exemplary embodiment of the present invention, the pressure-sensitive adhesive layer may be a pressure-sensitive adhesive mixed with different acrylic copolymer resins in a predetermined ratio, and added with a crosslinking agent. It is possible to control the modulus and adhesive force of the pressure-sensitive adhesive according to the content of the crosslinking agent.

In the present invention, when the polarizer in which the mask layer including the perforated portion is formed is immersed in the decolorizing solution, the decolorizing solution comes into contact with the polyvinyl alcohol-based polarizer through the perforated portion, and as a result, only the portion corresponding to the perforated region is partially. Discoloration will occur.

In addition, the said perforation part should just be formed so that it may correspond to the shape of the area | region which wants to discolor, and the form, formation position, etc. are not specifically limited. For example, the perforation part may be formed to correspond to the shape of the part at a position where a component such as a camera is mounted, may be formed in the shape of a product logo in the area where the product logo is printed, In the case of providing color, the frame may be formed on the edge of the polarizer.

According to the exemplary embodiment of the present invention, before the forming of the discoloration region, the method may further include providing a release film on an opposite surface of the mask film opposite to the polarizer of the protective film.

After the release film is further provided, a decolorization process may be performed to minimize sagging due to MD shrinkage caused by polarizer swelling.

In the present invention, the protective film of the mask film is removed after local discoloration, there is a difference from the protective film of the polarizing plate for protecting the polarizing plate. The removing of the mask layer may be performed by a method of peeling the mask layer from the polarizer. More specifically, the removing of the mask layer may be performed by a method of peeling the mask layer from the polarizer using a peeling roll or the like.

In this invention, when processing the part corresponding to a perforation part, a decoloring solution can be used. In this case, the decolorizing solution is preferably a strong base solution having a pH of 11 to 14, more specifically, sodium hydroxide (NaOH), sodium sulfate (NaSH), sodium azide (NaN3), potassium hydroxide (KOH), sulfuric acid Potassium sulfide (KSH) and potassium thiosulfate (KS2O3) may be one containing at least one bleaching agent selected from the group consisting of. On the other hand, the concentration of the decolorant in the decolorizing solution is preferably about 1% to 30% by weight, the viscosity of the decolorizing solution may be about 1cps to 2000cps, preferably about 5cps to 2000cps. When the viscosity of the decolorizing solution satisfies the numerical range, the printing process can be performed smoothly, and can be prevented from diffusing or flowing down in the printed decolorizing solution according to the movement of the polarizing member in the continuous processing line, thereby This is because the discoloration region can be formed in a desired shape in the region. On the other hand, the viscosity of the decolorizing solution may be appropriately changed depending on the printing device used, the surface characteristics of the polarizer. For example, when using the gravure printing method, the viscosity of the decolorizing solution may be about 1cps to 2000cps, preferably about 5cps to 200cps, when using the inkjet printing method, the viscosity of the decolorizing solution is about 1cps to 55cps, Preferably it may be about 5cps to 20cps.

According to one embodiment of the present invention, the decolorizing solution may further include a thickener. In order for the viscosity of the said bleaching solution to satisfy | fill the said range, it is preferable to use the method of adding a thickener further. Therefore, the thickener improves the viscosity of the decolorizing solution, thereby suppressing the diffusion of the solution and helping to form a decolorizing region at a desired size and location. When a high viscosity solution is applied to a fast-moving polarizer, the difference in the relative velocity of the liquid and the polarizer during application is reduced to prevent the solution from spreading to an undesired area. Can be reduced to form a bleaching area of the desired position or size.

The thickener is not particularly limited as long as it has low reactivity and can increase the viscosity of the solution. According to one embodiment of the present invention, the thickener is polyvinyl alcohol-based resin, polyvinylacetoacetate-based resin, acetoacetyl group-modified polyvinyl alcohol-based resin, butenediol vinyl alcohol-based, polyethylene glycol-based resin and polyacrylamide It includes at least one selected from the group consisting of resins.

According to another exemplary embodiment, the thickener may be included in an amount of 0.5 wt% to 30 wt% with respect to the total weight of the decolorizing solution. Specifically, according to the exemplary embodiment of the present invention, the thickener may be included in an amount of 2.5 wt% to 15 wt% with respect to the total weight of the decolorizing solution. If the content of the thickener exceeds the above range, the viscosity is so high that the washing is not effective, and if the content of the thickener is too low, the viscosity is low to realize the discoloration area of the desired shape and size by the diffusion and flow of the liquid. Hard.

According to an exemplary embodiment of the present invention, the decolorizing solution is 1% by weight to 30% by weight of a decolorant based on the total weight; Thickener 0.5% to 30% by weight; And 40% to 70% by weight of water.

On the other hand, it will be described in detail the mechanism that the polarization is resolved through the decolorization step of the present invention.

It is known that composites of polyvinyl alcohols, in which iodine and / or dichroic dyes have been dyed, can absorb light in the visible range, such as 400 nm to 800 nm. In this case, when the decolorizing solution is in contact with the polarizer, iodine and / or dichroic dyes absorbing light in the visible wavelength range present in the polarizer are decomposed, thereby decolorizing the polarizer to increase transmittance and lower polarization degree.

For example, when an aqueous solution containing potassium hydroxide (KOH), which is a decolorizing agent, is brought into contact with a portion of the polyvinyl alcohol polarizer in which iodine is salted, iodine is decomposed by a series of processes as shown in Formulas 1 and 2 below. . On the other hand, when the boric acid cross-linking process in the manufacture of the polyvinyl alcohol polarizer iodine-dyed, potassium hydroxide directly decomposes the boric acid, as described in the following formula 3, to remove the cross-linking effect through hydrogen bonding of polyvinyl alcohol and boric acid Done.

[Formula 1]

12KOH + 6I ₂ → 2KIO ₃ + 10KI + 6H ₂ O

[Formula 2]

_{^{I 5 - + IO 3 - +}} 6H + → 3I 2 + 3H 2 O

_{^{I 3 - → I - + I}} 2

[Formula 3]

B (OH) ₃ + ₃ KOH → K ₃ BO ₃ + 3H ₂ O

That is, by absorbing visible light ^{_{I 5 - (620nm), I}} 3 - (340nm), I 2 - decomposing the iodine and / or iodine ion complexes, such as (460nm), I ^- (300nm or less), or It produces salts, which transmit most of the light in the visible range. As a result, the polarization function is eliminated in the region of 400 nm to 800 nm, which is the visible light region of the polarizer, thereby increasing the overall transmittance, thereby making the polarizer transparent. In other words, the polarized function may be resolved by decomposing the arranged iodine complex that absorbs visible light into a monomolecular form that does not absorb visible light in order to make polarized light in the polarizer.

According to an exemplary embodiment of the present invention, the method may further include washing with an alcohol or an acid solution after forming the decolorizing region. If the remaining decolorizing solution is not properly washed in the step of forming the decolorizing region, the solution may diffuse or remain on the polarizer, so that the decolorizing region may be formed in an undesired size and shape, and to form a decolorizing region having a fine size. It is difficult.

In particular, in the case of the alcohol, it is easy to dry and can be easily removed, and can be suitably used in polarizers other than the decoloring region because it does not affect the transmittance or the degree of polarization. For example, the alcohol is preferably, but not limited to, ethanol, methanol, propanol, butanol, isopropyl alcohol, or a mixture thereof. In addition, in the case of the acid solution, the residual decolorant which is mainly basic is neutralized with the acid solution, and is removed. As the acid solution, for example, aqueous acetic acid solution, adipic acid solution, boric acid solution, phosphoric acid solution, and lactic acid solution Aqueous sulfuric acid solution, nitric acid solution or a mixed solution thereof may be used, but is not limited thereto.

The washing may be performed by immersing the polarizer in alcohol for 1 second to 180 seconds, more preferably 3 to 30 seconds, or by using a dispenser or ink jet or the like on a localized region which has been contacted with a decolorizing solution by using alcohol or an acid. A method of applying a solution may be used.

In the method of manufacturing a polarizing plate including a decolorizing region according to an exemplary embodiment of the present invention, by using a decolorizing agent and then washing with an alcohol or an acid solution, the iodine compound and the salt formed by the decolorizing agent are washed away as described above, and the decolorizing region. The content of iodine and iodine ion complexes is minimized. Therefore, the absorption of light of the residual iodine and iodine ion complex in the decoloring region is reduced, resulting in a more transparent effect.

In the present invention, the edge roughness of the discoloration portion is 30 µm or less, preferably 20 µm or less, and the closer to 0 µm or 0 µm, the better.

In the present invention, the edge roughness means the sum of the maximum outer difference and the maximum inner difference in the circle at the line drawn at every two degrees at any point of the discoloration part. 4 schematically illustrates a method of measuring the edge roughness. When the edge roughness is 30 µm or less, the shape of the discoloration portion becomes clearer. The value is closer to 0 mu m or 0 mu m. This means that when the discoloration portion is placed on the lens portion of the device such as the camera module, the function of the device is not deteriorated.

According to an exemplary embodiment of the present invention, after the forming of the discoloration region, the method may further include forming an optical layer on at least one surface of the polarizer. In this case, the optical layer may be a polymer film layer such as a protective film or a retardation film, a functional film layer such as a brightness enhancement film, or may be a functional layer such as a hard coating layer, an antireflection layer, or an adhesive layer.

More specifically, according to the exemplary embodiment of the present invention, the optical layer is formed on the other surface of the polarizer. In other words, the optical layer is formed on a surface which is not provided with the protective film and the release film of the polarizer.

On the other hand, the optical layer may be directly attached or formed on the polyvinyl alcohol-based polarizer side, or may be attached on a protective film or other coating layer attached to one side of the polyvinyl alcohol-based polarizer.

The method of forming the optical layer may be formed by different methods according to the type of optical layer to be formed, for example, may be formed using optical layer forming methods well known in the art, the method This is not particularly limited.

According to an exemplary embodiment of the present invention, the method may further include removing the release film after the forming of the discoloration region. The removing of the release film may be performed by a method of peeling off the release film from the protective film. More specifically, the removing of the release film may be performed by a method of peeling the release film from the protective film using a peeling roll or the like.

Since the release film plays a role of suppressing sagging occurring in the decolorizing area forming step (stretching in the direction of the protective film), it is preferable that the release film is removed after the decolorizing area is formed.

The decoloring region of the present invention may mean a non-polarization part. Therefore, the polarizer which has a non-polarization part can be manufactured using the said mask film.

In this case, the polarizer is not particularly limited, and a film made of polyvinyl alcohol (PVA) containing a polarizer well known in the art, for example, iodine or a dichroic dye, is used.

The polarizer may have a thickness of at least 1 μm, at least 3 μm, at least 5 μm, at least 7 μm, or at least 10 μm, at least 20 μm. At the same time, the thickness of the polarizer may be 30 μm or less, preferably 25 μm or less.

The polarizer of the present invention as described above can be used in the manufacture of a polarizing plate. More specifically, the method of manufacturing a polarizing plate of the present invention comprises the steps of laminating the mask film on one surface of the polarizer; And decolorizing the portion corresponding to the perforated portion of the mask film and removing the mask film on one surface of the polarizer.

The method of manufacturing a polarizing plate of the present invention may include laminating a protective film of the polarizer on a surface from which the mask film is removed.

As the protective film of the polarizer, those generally known in the art may be used. For example, cellulose resins such as diacetyl cellulose, reacetyl cellulose, (meth) acrylic resins, cycloolefin resins, and polypropylenes. Ester resins, such as olefin resins, such as a polyethylene terephthalate resin, a polyamide resin, a polycarbonate resin, and copolymer resins thereof, can be used, but is not limited thereto.

The polarizing plate manufactured by the said manufacturing method of this invention is a polarizer which has the said non-polarization part; And it characterized in that it comprises a protective film of the polarizing plate on at least one surface of the polarizer.

In an exemplary embodiment of the present invention, the polarizer has at least one decolorization region, the decolorization region has a single transmittance of 80% or more and a polarization degree of 10% or less in the wavelength range of 400 nm to 800 nm, and maximum sagging of the decolorization region. It provides a polarizing plate having a sagging depth of 10 μm or less.

According to an exemplary embodiment of the present invention, the area of at least one of the color fading areas may be 0.5 mm 2 or more and 500 mm 2 or less, preferably 0.5 mm 2 or more and 200 mm 2 or less.

According to one embodiment of the present invention, the size of the non-polarization portion may be 0.5 mm 2 or more and 500 mm 2 or less, and the polarizing plate including the non-polarization portion having an edge roughness of the non-polarization portion is 30 μm or less.

In the present invention, the sagging means sagging in the direction of the protective film generated when the polyvinyl alcohol (PVA) polarizer is in contact with the decolorizing solution.

Specifically, the shallower the depth of sagging, the smaller the degree of deflection phenomenon, and can minimize the distortion of the appearance of the polarizing plate (distortion), the adhesive is uniformly applied when laminating a protective film on the other side There is an advantage that it can. As a result, it is possible to reduce the occurrence of defects in the production of a polarizing plate having a protective film on both sides of the polarizer.

In addition, the shallower the depth of the sagging has the advantage that it can provide a polarizing plate with improved appearance.

According to one embodiment of the present invention, the maximum sagging depth of the discoloration area may be 8 μm or less, 7 μm or less, or 6 μm or less.

The depth of the sagging may be measured using a white light optical profiler or a confocal laser scanning microscope (CLSM).

The depth of the sagging may mean a value obtained by subtracting the minimum value from the maximum value of the gap between the opposite surface of the protective film and the opposite surface of the protective film of the polarizer. In addition, the depth of the sagging may mean the height difference between the discolored region and the non-discolored region in the protective film when the polarizing plate is placed on the plane.

According to an exemplary embodiment of the present invention, a polarizing plate having a single transmittance of 80% or more in a wavelength range of 400 nm to 800 nm included in the visible light region, an arithmetic mean roughness Ra of 200 nm or less, and a polarization degree of 10% or less Have

As described above, the decolorizing region refers to a region formed through a process of selectively contacting a decolorizing solution with a part of a polyvinyl alcohol polarizer in which iodine and / or a dichroic dye is dyed.

The color fading region is preferably 80% or more, 90% or more, and still more preferably 92% or more in the wavelength range of 400 nm to 800 nm, more preferably 450 nm to 750 nm, which is the visible light region. Moreover, it is more preferable that the said discoloration area | region is polarization degree 10% or less, and 5% or less. The higher the unitary transmittance of the decoloring area and the lower the degree of polarization, the better the visibility, thereby further improving the performance and image quality of the camera lens to be located in the area.

According to an exemplary embodiment of the present invention, it is preferable that the unit transmittance of the region except the discoloring region of the polarizing plate is 40% to 47%, more preferably 42% to 47%. Furthermore, it is preferable that polarization degree is 99% or more in the area | region except the discoloration area | region of the said polarizing plate. This is because the remaining region except the discoloration region should exhibit the same excellent optical properties as the above range by functioning as the original polarizing plate.

According to an exemplary embodiment of the present invention, the arithmetic mean roughness Ra of the decoloring region may be 200 nm or less, specifically, 100 nm or less or 80 nm or less, more specifically, 50 nm or less.

According to an exemplary embodiment of the present invention, the square root mean square roughness Rq of the discoloration region may be 200 nm or less, and specifically, 100 nm or less or 80 nm or less, more specifically, 50 nm or less.

The arithmetic mean roughness Ra is a value defined in JIS B0601-1994, which is extracted from the roughness curve by the reference length in the direction of the average line, and the absolute value of the deviation from the average line of the extract portion to the measurement curve is summed. The average value is shown, and the square mean square roughness Rq is defined in JIS B0601-2001. The arithmetic mean roughness Ra and the square root mean square roughness Rq are measured by an optical profiler (Nanoview E1000, Nanosystem Co., Ltd.).

In general, when the roughness of the surface of the polarizer is increased, the haze is increased by refraction and reflection of light. When the roughness of the discoloration region satisfies the above range, the haze is sufficiently low and can have clear visibility.

According to one embodiment of the present invention, the haze of the discoloration region is 3% or less, preferably 2% or less, and more preferably 1% or less.

According to one embodiment of the present invention, the discoloration area is 0.1 to 0.5% by weight, preferably 0.1 to 0.35% by weight of the iodine and / or dichroic dye. This is because, as described above, the iodine that was present in the complex form on the polarizer is washed away by the reaction between the decolorant and the iodine, and thus the content of iodine and / or dichroic dye is greatly reduced, thereby greatly improving the permeability. do.

In contrast, according to an exemplary embodiment of the present invention, the region excluding the decolorizing region has a content of iodine and / or a dichroic dye in an amount of 1% by weight to 4% by weight, preferably 2% by weight to 4% by weight. .

At this time, the content of the iodine and / or the dichroic dye was measured using an optical X-ray analyzer (manufactured by Rigaku Electric Industries, Ltd., trade name "ZSX Primus II"). In the present invention, using a sample in the form of a polarizer sheet having a size of 40 mm × 40 mm and a thickness of 12 μm, the average weight percent per volume of 19.2 mm ³ was measured.

According to another exemplary embodiment, the discoloration area may be 0.005% to 40% of the area of the entire polarizing plate.

The image display device can be made using the polarizing plate according to the present invention as described above.

More specifically, the present invention, a display panel; And a polarizing plate according to the above-described exemplary embodiment attached to one or both surfaces of the display panel.

The display panel may be a liquid crystal panel, a plasma panel, and an organic light emitting panel. Accordingly, the image display device may be a liquid crystal display (LCD), a plasma display (PDP), and an organic light emitting display (OLED). .

More specifically, the image display device may be a liquid crystal display device including a liquid crystal panel and polarizing plates provided on both sides of the liquid crystal panel, wherein at least one of the polarizing plates according to the above-described exemplary embodiment of the present invention. It may be a polarizing plate including a polarizer. That is, the polarizing plate comprises a polyvinyl alcohol polarizer in which iodine and / or dichroic dye is dyed and a protective film provided on at least one surface of the polyvinyl alcohol polarizer, in a wavelength range of 400 nm to 800 nm. Has a single color transmittance of 80% or more, arithmetic mean roughness Ra of the color fading area is 200 nm or less, polarization degree is 10% or less, and sagging is 10 μm or less.

In this case, the type of liquid crystal panel included in the liquid crystal display device is not particularly limited. For example, a panel of a passive matrix type such as, but not limited to, a twisted nematic (TN) type, a super twisted nematic (STN) type, a ferrolectic (F) type, or a polymer dispersed (PD) type; Active matrix panels such as two-terminal or three-terminal; All known panels, such as an In Plane Switching (IPS) panel and a Vertical Alignment (VA) panel, can be applied. In addition, the type of other components constituting the liquid crystal display device, for example, upper and lower substrates (for example, color filter substrates or array substrates) is not particularly limited, and the configurations known in the art are not limited. Can be employed.

According to an exemplary embodiment of the present invention, the image display apparatus may be an image display apparatus further comprising a camera module provided in the discoloration area of the polarizing plate. By positioning the camera module in the decolorized area where the transmittance of the visible light region is improved and the polarization degree is eliminated, it is possible to bring about an effect of increasing the visibility of the camera lens portion, and by including a polarizing plate which suppresses the sagging of the decolored area, thereby improving the appearance. It can also have an effect.

Hereinafter, the present invention will be described in detail with reference to Examples. However, embodiments according to the present invention can be modified in many different forms, the scope of the invention is not to be construed as limited to the embodiments described below. Embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

<Production of Polarizing Plate>

<Production example>

After swelling the polyvinyl alcohol-based film (M3000 grade, Nippon Synthetic Co., Ltd., 30 μm in thickness) for 15 seconds in a 25 ° C. pure water solution, a dyeing process was performed for 60 seconds in a 0.2 wt% concentration and a 25 ° C. iodine solution. Thereafter, the boric acid 1wt%, after the washing process for 30 seconds in a 45 ℃ solution was carried out a 6-fold stretching process in a solution of boric acid 2.5wt%, 52 ℃. In addition, a polarizer having a thickness of 12 μm was prepared by performing a complementary color process in a 5 wt% KI solution after the stretching process and drying in an oven at 60 ° C. for 5 minutes. Then, a polarizing plate having a protective film was prepared by laminating a TAC film using an adhesive on one surface of the polarizer.

<Production of Adhesives>

a. Copolymer Resin (A) Preparation

94 parts by weight of butyl acrylate, 1 part by weight of 2-hydroxyethyl (meth) acrylate, 5 parts of acrylic acid, in 100 parts by weight of the total reactants in a 1 L reactor equipped with a refrigeration system for easy reflux of nitrogen gas and easy temperature control. Part by weight was added. Then, after purging nitrogen gas for 20 minutes to remove oxygen in the reactor, the temperature of the reactor was maintained at 60 ° C. Thereafter, 0.03 parts by weight of azobisisobutyronitrile, a reaction initiator, was diluted and injected into ethyl acetate at 50% concentration. After reacting for 8 hours, the final acrylic polymer (A) was obtained.

b. Copolymer Resin (B) Preparation

91 parts by weight of butyl acrylate, 1 part by weight of 2-hydroxyethyl (meth) acrylate, 4 parts of acrylic acid, in 100 parts by weight of the total reactants in a 1 L reactor equipped with a refrigeration system for easy control of nitrogen gas. By weight, a monomer mixture consisting of 4 parts by weight of methacryloyl polymethylmethacrylate was added thereto, and 100 parts by weight of ethyl acetate was added as a solvent. Then, after purging nitrogen gas for 20 minutes to remove oxygen inside the reactor, the temperature of the reactor was maintained at 65 ° C. Thereafter, 0.03 parts by weight of azobisisobutyronitrile, a reaction initiator, was diluted and injected into ethyl acetate at a concentration of 50% to react for 8 hours to obtain an acrylic polymer material (B).

c. combination

The tolylene diisocyanate adduct of trimethylolpropane, an isocyanate-based crosslinking agent, was diluted to 50% by ethyl acetate solution based on 100 parts by weight of the copolymer obtained by mixing the acrylic copolymers A and B obtained from the copolymerization at a weight ratio of 9: 1. A small amount was added to prepare an adhesive. It is possible to control the modulus and adhesive force of the pressure-sensitive adhesive according to the content of the crosslinking agent.

<Production of Polarizing Plate with Local Discoloration Area>

a. Preparation Example 1

A pressure-sensitive adhesive layer was formed by coating an acrylic pressure-sensitive adhesive having a pressure of 2 kgf / in with a thickness of 15 μm on a PET protective film having a thickness of 50 μm, measured according to the measurement method described in the specification, and forming a pressure-sensitive adhesive layer on the pressure-sensitive adhesive layer by 15 μm PET. A mask film was prepared by laminating a release film. Thereafter, a hole (perforated part) having a diameter of 3 mm was punched in the mask film at 30 cm intervals using a CO ₂ laser at an output of 10 W and a pulse repetition rate of 20 kHz. After removing the release film of the perforated mask film, laminated on the surface without the protective film of the polarizing plate prepared in the manufacturing example, the portion of the KOH 10wt%, 50 ° C solution and the same as the mask film hole (perforated part) After decolorizing, it was neutralized by immersing in 50 ℃ citric acid 5wt% aqueous solution for 10 seconds for washing, and dried at 60 ℃ for 5 minutes. Thereafter, the mask film was removed, and a TAC protective film was laminated using the adhesive on the removed surface to prepare a polarizing plate having a local discoloration part. As described above, the adhesive force was measured by reciprocating five times at a speed of 300 mm / min with a 2 kg roll in accordance with JIS Z 0237, waiting for 30 minutes, and peeling 180 degrees at a rate of 5 mm / sec using a TA Texture Analyzer.

b. Preparation Examples 2 to 8

On the PET protective film with a thickness of 50㎛, adhesives with 10kgf / in, 50kgf / in, 100kgf / in, 0.5kgf / in, 1kgf / in, 150kgf / in, 200kgf / in, respectively, are coated with a thickness of 15㎛ A polarizing plate having a localized discoloration area was manufactured in the same manner as in Production Example 1, except that the adhesive layer was formed.

Experimental Example 1

A mask film having a modulus having an adhesive force corresponding to Preparation Examples 1 to 8 was attached to the polarizing plate of Preparation Example in a size of 2 cm X 2 cm, and Nichiban's CT-24 tape was attached to the top of the mask film after 1 hour. It was. Thereafter, the peeling of the mask film when the tape was removed at an angle of 180 degrees was observed. Y when the peeling of the mask film occurred and N when peeling did not show in Table 1 below.

Experimental Example 2

Edge roughness was measured by calculating the sum of the maximum outside circumference and the maximum inside inside circumference of the circle at every 2 degrees at an arbitrary point of the discoloration part of the polarizing plates corresponding to Production Examples 1 to 8. The results were shown in Table 1 below.

Experimental Example 3

In order to confirm whether there exists a bubble generation part like FIG. 5, the discoloration part of the polarizing plate corresponding to manufacture examples 1-8 was visually inspected. In the following Table 1, the case where five or more perforated 100 reference bubbles of the polarizing plate is shown is represented by Y, and the case where the perforated 100 reference bubbles are displayed between 0 and 4 is represented by N.

Thickness (㎛) Adhesion (kgf / in) E (μm) Whether the film is peeled off Bubble generation Example 1 15 2 27 Y N Example 2 15 10 25 Y N Example 3 15 50 25 Y N Example 4 15 100 22 Y N Comparative Example 1 15 0.5 50 Y Y Comparative Example 2 15 One 47 Y Y Comparative Example 3 15 150 70 N N Comparative Example 4 15 200 80 N N

In Table 1, Preparation Examples 1 to 4 correspond to Examples 1 to 4, and Preparation Examples 5 to 8 correspond to Comparative Examples 1 to 4. In addition, in Table 1, in Table 1, the thickness and the adhesive force means the thickness and the adhesive force of the mask film adhesive, E means the edge roughness (Edge Roughness).

Through the experiments, it was confirmed that the edge roughness of the adhesive film of the pressure-sensitive adhesive of the mask film has a value of 30 μm or less. Moreover, only when it satisfy | filled the said range, it was confirmed that peeling of a mask film is easy, without foaming generate | occur | producing. This means that a polarizing plate having a suitable non-polarization portion that does not degrade the function of the device when the discoloring portion is placed on the lens portion of the device such as a camera module can be made.

Claims (9)

Protective film;
Has an adhesive layer provided on one side of the protective film,
The adhesive force of the pressure-sensitive adhesive layer is 2kgf / in to 100kgf / in,
Mask film having a through-hole penetrating the protective film and the pressure-sensitive adhesive layer integrally. The method of claim 1,
A mask film further having a release film detachably attached to the said adhesive layer. The method of claim 2,
The perforated part is a mask film that penetrates the protective film, the pressure-sensitive adhesive layer and the release film integrally. The method of claim 1,
The mask film used for forming a discoloration part by processing the part corresponding to the said perforation part after laminating | stacking the said mask film on one surface of a polarizer. Stacking the mask film of claim 1 on one surface of the polarizer;
Decolorizing a portion corresponding to the perforated portion of the mask film; And
Method of manufacturing a polarizing plate having a non-polarization portion comprising the step of removing the mask film. The method of claim 5,
The method of manufacturing a polarizing plate having a non-polarization part further comprising the step of laminating a protective film of the polarizer on the surface from which the mask film is removed. The polarizing plate which has a non-polarization part manufactured by the manufacturing method of Claim 5 or 6. The method of claim 7, wherein
Edge roughness (Edge Roughness) of the non-polarization portion is 30㎛ or less. An image display device comprising the polarizing plate according to claim 7.

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