阅读说明：本技术 使用掩模膜制造偏光板的方法和通过其制造的偏光板 (Method for manufacturing polarizing plate using mask film and polarizing plate manufactured thereby ) 是由 李炳鲜 罗钧日 于 2019-08-22 设计创作，主要内容包括：本说明书涉及使用用于制造具有局部脱色区域的偏光板的掩模膜制造偏光板的方法和使用其制造的偏光板。(The present specification relates to a method of manufacturing a polarizing plate using a mask film for manufacturing a polarizing plate having a local discolored region and a polarizing plate manufactured using the same.)

1. A method for manufacturing a polarizing plate having a non-polarizing portion, the method comprising:

preparing a mask film having a protective film, an adhesive layer disposed on one surface of the protective film, and a perforated portion integrally penetrating the protective film and the adhesive layer, wherein the adhesive layer has a thickness of 6 to 80 μm;

laminating the mask film on both surfaces of a polarizer;

decolorizing a portion corresponding to the perforated portion of the mask film; and

the mask film is removed.

2. The method for manufacturing a polarizing plate having a non-polarizing portion according to claim 1, further comprising laminating a protective film of the polarizer on the surface from which the mask film is removed.

3. A laminate, comprising:

a polarizer; and

mask films disposed on both surfaces of the polarizer,

wherein the mask film has a protective film, an adhesive layer provided on one surface of the protective film, and a perforated portion integrally penetrating the protective film and the adhesive layer.

4. A polarizing plate having a non-polarizing portion manufactured using the manufacturing method according to claim 1 or 2.

5. The polarizing plate of claim 4, wherein the non-polarizing portion has an edge roughness of 30 μm or less.

6. An image display device comprising the polarizing plate according to claim 4.

Technical Field

The specification claims priority and benefit of korean patent application No. 10-2018-0097780, filed on 22.8.8.2018 to the korean intellectual property office, the entire contents of which are incorporated herein by reference.

The present disclosure relates to a mask film for manufacturing a polarizing plate having a local discolored region through chemical treatment and a method of manufacturing a polarizing plate using the same.

Background

Polarizing plates have been used for various display devices such as liquid crystal display devices and organic light emitting diodes. Currently, a polarizing plate mainly used is used in the following form: a polyvinyl alcohol (hereinafter, PVA) -based film is dyed with iodine and/or dichroic dyes, the iodine and/or dichroic dyes are crosslinked using boric acid or the like, the resultant is oriented using a stretching method to prepare a PVA polarizer, and a protective film is laminated on one surface or both surfaces of the prepared PVA polarizer.

Meanwhile, recent display devices tend to be slimmer, and the thickness of a bezel unit that does not display a screen and the thickness of an edge tend to be minimized to obtain a large screen. Further, components such as a video camera tend to be mounted in a display device to exhibit various functions, and attempts have been made to provide various colors or decolor in a product logo or an edge area in consideration of design factors.

However, in the existing polarizing plate, the entire area of the polarizing plate is dyed with iodine and/or dichroic dye, and thus, the polarizing plate shows deep black, and as a result, it is difficult to provide various colors to a display device, and particularly, when the polarizing plate is placed on a component such as a camera, the polarizing plate absorbs 50% or more of light amount, causing a problem such as a reduction in visibility of a camera lens.

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

However, such a physical method reduces the appearance of the image display device and may damage the polarizing plate due to the nature of the drilling process. Meanwhile, in order to prevent damage such as tearing of the polarizing plate, the perforated portion of the polarizing plate needs to be formed in an area sufficiently distant from the edge, and thus when such a polarizing plate is used, the bezel unit of the image display device becomes relatively wide, which departs from the recent trend of narrow bezel design in the image display device. Further, when the camera module is mounted on the perforated portion of the polarizing plate as above, the camera lens is exposed to the outside, and there is also caused a problem that contamination and damage easily occur in the camera lens when used for a long period of time.

Disclosure of Invention

Technical problem

The present disclosure is made in view of the above, and relates to providing a polarizing plate having excellent surface roughness and haze by minimizing wrinkles in a depolarization region while eliminating polarization unlike physical punching of holes in the art, by providing a mask film for manufacturing a polarizing plate having a local discoloration region through chemical treatment.

The present disclosure relates to providing a method of manufacturing a polarizing plate using a mask film for manufacturing a polarizing plate having a local discolored region through chemical treatment with excellent process efficiency and a polarizing plate manufactured using the same.

Technical scheme

One embodiment of the present disclosure provides a method for manufacturing a polarizing plate having a non-polarizing part, the method including: preparing a mask film having a protective film, an adhesive layer disposed on one surface of the protective film, and a perforated portion integrally penetrating the protective film and the adhesive layer, wherein the adhesive layer has a thickness of 6 to 80 μm; laminating mask films on both surfaces of the polarizer; decolorizing a portion corresponding to the perforated portion of the mask film; and removing the mask film.

Another embodiment of the present disclosure provides a laminate including a polarizer; and mask films disposed on both surfaces of the polarizer, wherein the mask films have a protective film, an adhesive layer disposed on one surface of the protective film, and a perforated portion integrally perforated through the protective film and the adhesive layer.

Another embodiment of the present disclosure provides a polarizing plate having a non-polarizing portion manufactured according to the method for manufacturing a polarizing plate of the present disclosure.

Another embodiment of the present disclosure provides an image display device including the polarizing plate described above.

Advantageous effects

The mask film according to one embodiment of the present disclosure can increase the precision of perforation when forming perforated portions in the mask film by adjusting the thickness of the adhesive within a specific range and prevent the adhesive from flowing out during a roll-to-roll process, and provides an advantage of excellent process efficiency by laminating the mask film on both surfaces of a polarizer having iodine or dichroic dye and decoloring, the decoloring rate is high, and only a target portion can be decolored.

Drawings

Fig. 1 illustrates a mask film formed of a protective film and an adhesive layer according to one embodiment of the present disclosure.

Fig. 2 illustrates a mask film formed of a protective film, an adhesive layer, and a release film according to one embodiment of the present disclosure.

Fig. 3 illustrates a method for manufacturing a polarizing plate according to one embodiment of the present disclosure.

Fig. 4 schematically illustrates a method of measuring edge roughness according to one embodiment of the present disclosure.

Fig. 5 shows a phenomenon of the adhesive slipping.

Fig. 6 is a photograph taken using a polarizer having a discolored portion satisfying an edge roughness of 30 μm or less in a lens.

Fig. 7 is a photograph taken in a lens using a polarizer having a discolored portion with an edge roughness of more than 30 μm.

Detailed Description

Hereinafter, preferred embodiments of the present disclosure will be described. However, the embodiments of the present disclosure may be modified into various other forms, and the scope of the present disclosure is not limited to the embodiments described below. Furthermore, embodiments of the present disclosure are provided to more fully describe the present disclosure to those of ordinary skill in the art.

In the present specification, "perforated portion" means a portion having a hole.

In the present specification, (meth) acrylic acid means acrylic acid or methacrylic acid.

In the present specification, (meth) acrylate means acrylate or methacrylate.

One embodiment of the present disclosure provides a method for manufacturing a polarizing plate having a non-polarizing part, the method including: preparing a mask film having a protective film, an adhesive layer disposed on one surface of the protective film, and a perforated portion integrally penetrating the protective film and the adhesive layer, wherein the adhesive layer has a thickness of 6 to 80 μm; laminating mask films on both surfaces of the polarizer; decolorizing a portion corresponding to the perforated portion of the mask film; and removing the mask film. By laminating mask films on both surfaces, local decoloring of the polarizer can be quickly performed.

The thickness of the adhesive may be 6 μm to 80 μm, preferably 6 μm to 30 μm. The adhesive thickness of less than 6 μm has a problem of lowering coating uniformity, and when the mask film is removed after the decoloring reaction, a phenomenon in which the adhesive is transferred to the polarizer surface occurs. The adhesive having a thickness of more than 80 μm has problems in that the perforation is not precise due to the slipping of the adhesive occurring when perforating the mask film, or the adhesive flows out due to the pressing of the adhesive, and the adhesive also flows out when laminating the perforated mask film on the polarizer.

In one embodiment of the present disclosure, the mask film may further have a release film attached to the adhesive layer, and the release film may be separated from the adhesive layer.

In another embodiment of the present disclosure, the mask film may have a perforated portion integrally perforated through the protective film, the adhesive layer, and the release film.

In one embodiment of the present disclosure, there are two or more perforated portions, and they are arranged at predetermined intervals in the length direction of the mask film.

In one embodiment of the present disclosure, there are two or more perforated portions, and they are arranged equidistantly in at least the length direction of the mask film.

In one embodiment of the present disclosure, there are two or more perforated portions, and they are arranged equidistantly in the length direction of the mask film and the width direction of the mask film.

Fig. 1 illustrates a mask film formed of a protective film and an adhesive layer according to one embodiment of the present disclosure.

Fig. 2 illustrates a mask film formed of a protective film, an adhesive layer, and a release film according to one embodiment of the present disclosure.

The relatively dark portion in each of fig. 1 and 2 means a perforated portion passing through the mask film.

The formation of the perforated portion in the mask film is not particularly limited, and may be performed by a film perforation method known in the art, such as die processing, cutter processing, or laser processing.

According to one embodiment of the present disclosure, the formation of the perforated portion may be performed by laser machining. The laser processing may be performed using a laser processing apparatus generally known in the art, and is not particularly limited. The conditions of the laser processing (e.g., laser device type, output, and laser pulse repetition rate) may differ depending on the material and thickness of the film, the shape of the perforated portion, and the like, and those skilled in the art may appropriately select the laser processing conditions in consideration of factors such as the above. For example, when a polyolefin film having a thickness of 30 to 100 μm is used as the protective film of the mask film, the perforated portion may use carbon dioxide (CO) having a peak wavelength of about 9 to 11 μm₂) A laser device or an Ultraviolet (UV) device having a peak wavelength of about 300nm to 400nm, and herein, the maximum average output of the laser device may be about 0.1W to 30W, and the pulse repetition rate may be about 0kHz to 50kHz, however, the conditions are not limited thereto.

As the protective film of the mask film of the present disclosure, an olefin-based film, such as Polyethylene (PE), polypropylene (PP), or polyethylene terephthalate (PET); or a vinyl acetate-based film such as Ethylene Vinyl Acetate (EVA) or polyvinyl acetate, however, the protective film of the mask film is not limited thereto. Further, although not limited thereto, the thickness of the mask film may be about 10 to 100 μm, preferably about 10 to 70 μm.

One embodiment of the present disclosure provides a laminate comprising: a polarizer; and the above-described mask film provided on each of both surfaces of the polarizer.

The local destaining regions of the present disclosure may be depolarizing regions.

Lamination of the mask film on both surfaces of the polarizer may be performed using a film lamination method known in the art (e.g., a method of attaching the mask film and the polarizing element by an adhesive layer), and herein, an adhesive such as an acryl-based adhesive, a silicone-based adhesive, an epoxy-based adhesive, or a rubber-based adhesive may be used as the adhesive layer, however, the adhesive layer is not limited thereto.

According to one embodiment of the present disclosure, the adhesive layer includes two different types of acryl-based copolymer resins. In addition, the adhesive layer may further include a crosslinking agent. The modulus and adhesive strength of the adhesive can be controlled according to the content of the crosslinking agent.

In the present specification, two types of acryl-based copolymer resins may be represented as a first acryl-based copolymer resin and a second acryl-based copolymer resin, respectively. Further, the first acryl-based copolymer resin may be represented as a copolymer resin a, and the second acryl-based copolymer resin may be represented as a copolymer resin B.

As an embodiment, the adhesive layer may use an adhesive that: which is obtained by mixing two different types of acryl-based copolymer resins in a specific ratio, and adding a crosslinking agent thereto and mixing. The modulus and adhesive strength of the adhesive can be controlled according to the content of the crosslinking agent.

According to one embodiment of the present disclosure, the adhesive layer may include a first acryl-based copolymer resin; a second acryl-based copolymer resin; and a crosslinking agent.

More specifically, the adhesive layer may be obtained by mixing a first acryl-based copolymer resin and a second acryl-based copolymer resin, and adding a crosslinking agent thereto and mixing. The first acryl-based copolymer resin may be mixed in a ratio of 6 to 12 parts by weight, preferably 8 to 10 parts by weight, based on 1 part by weight of the second acryl-based copolymer resin.

According to one embodiment, the first acryl-based copolymer resin includes an alkyl (meth) acrylate; hydroxyalkyl (meth) acrylates; and (meth) acrylic acid.

More specifically, the first acryl-based copolymer resin may include 90 to 98 parts by weight of an alkyl (meth) acrylate, based on 100 parts by weight of the total monomers of the first acryl-based copolymer resin; 0.5 to 2 parts by weight of a hydroxyalkyl (meth) acrylate; and 1 to 8 parts by weight of (meth) acrylic acid, and preferably, 92 to 96 parts by weight of an alkyl (meth) acrylate based on 100 parts by weight of the total monomers of the first acryl-based copolymer resin; 0.5 to 1.5 parts by weight of a hydroxyalkyl (meth) acrylate; and 3 to 7 parts by weight of (meth) acrylic acid.

According to one embodiment, the second acryl-based copolymer resin includes an alkyl (meth) acrylate; hydroxyalkyl (meth) acrylates; (meth) acrylic acid; and polyalkyl (meth) acrylates.

More specifically, the first acryl-based copolymer resin may include 89 to 96 parts by weight of an alkyl (meth) acrylate, based on 100 parts by weight of the total monomers of the first acryl-based copolymer resin; 0.5 to 2 parts by weight of a hydroxyalkyl (meth) acrylate; 1 to 8 parts by weight of (meth) acrylic acid; and 1 to 8 parts by weight of a polyalkyl (meth) acrylate, and preferably, 90 to 95 parts by weight of the alkyl (meth) acrylate, based on 100 parts by weight of the total monomers of the first acryl-based copolymer resin; 0.5 to 1.5 parts by weight of a hydroxyalkyl (meth) acrylate; 2 to 6 parts by weight of (meth) acrylic acid; and 2 to 6 parts by weight of a polyalkyl (meth) acrylate.

In the present specification, the alkyl group contained in the alkyl (meth) acrylate may be linear or branched, and the number of carbon atoms of the alkyl group may be 1 to 20. The alkyl (meth) acrylate may include one, two or more selected from the group consisting of: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, and stearyl (meth) acrylate, but is not limited thereto.

The polyalkyl (meth) acrylate means that a plurality of alkyl groups are bonded in a repeating form in the alkyl (meth) acrylate.

In the present specification, the hydroxyalkyl (meth) acrylate may include one, two or more selected from the group consisting of: 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, and 2-hydroxyethylene glycol (meth) acrylate, but are not limited thereto.

According to one embodiment, the first acryl-based copolymer resin includes butyl acrylate; 2-hydroxyethyl (meth) acrylate; and acrylic acid.

According to one embodiment, the second acryl-based copolymer resin includes butyl acrylate; 2-hydroxyethyl (meth) acrylate; acrylic acid; and methacryloyl polymethyl methacrylate.

In the present disclosure, when a polarizer having a mask film including perforated portions laminated thereon is immersed in a decoloring solution, the decoloring solution is in contact with a polyvinyl alcohol-based polarizer through the perforated portions, and thus, decoloring occurs only partially in portions corresponding to the perforated portion regions.

Meanwhile, the perforated portion may be formed in a form corresponding to the region to be decolored, and the shape or the forming position is not particularly limited. For example, the perforated portion may be formed at a position where a component such as a camera is mounted to correspond to the shape of the component, may be formed to have a product logo shape in an area where a product logo is printed, or may be formed in a frame form on an edge portion of the polarizer when attempting to provide a color on the edge portion.

According to an embodiment of the present disclosure, before forming the discoloring region, a step of disposing a release film on a surface opposite to a surface of the protective film of the mask film facing the polarizer may be further included.

Performing the decoloring process after further disposing a release film has an advantage of minimizing sagging caused by MD shrinkage occurring due to swelling of the polarizer.

In the present disclosure, the protective film of the mask film is removed after the partial decoloring, and is different from a polarizing plate protective film for protecting a polarizing plate. The removal of the mask film may be performed using a method of peeling the mask film from the polarizer. More specifically, the removal of the mask film may be performed using a method of peeling the mask film from the polarizer using a peeling roller or the like.

In the present disclosure, when treating a portion corresponding to the perforated portion, a decoloring solution may be used. Herein, the decoloring solution is preferably a strongly alkaline solution having a pH of 11 to 14, and more specifically, may include one or more decoloring agents selected from: sodium hydroxide (NaOH), sodium hydrosulfide (NaSH), sodium azide (NaN)₃) Potassium hydroxide (KOH), potassium hydrosulfide (KSH) and potassium thiosulfate (KS)₂O₃). Meanwhile, the concentration of the decoloring agent in the decoloring solution is preferably about 1 to 30% by weight, and the viscosity of the decoloring solution may be about 1 to 2000cps, preferably about 5 to 2000 cps. When decolorizing the solutionWhen the viscosity of (b) satisfies the above numerical range, the printing process can be smoothly performed, and the printed decoloring solution can be prevented from being diffused or flowing down due to the movement of the polarizing element in the continuous production line, and thus, the decoloring area can be formed in a target shape in the target area. Meanwhile, the viscosity of the decoloring solution may be appropriately changed according to the printing apparatus used, the surface characteristics of the polarizer, and the like. For example, when the gravure printing method is used, the viscosity of the decoloring solution may be about 1 to 2000cps, preferably about 5 to 200cps, and when the inkjet printing method is used, the viscosity of the decoloring solution may be about 1 to 55cps, preferably about 5 to 20 cps.

According to one embodiment of the present disclosure, the decolorizing solution may also include a viscosity agent. In order to make the viscosity of the decoloring solution satisfy the above range, a method of further adding a viscosity agent is preferable. Thus, the viscosity agent suppresses the diffusion of the decolorized solution by enhancing the viscosity of the solution, and helps to form a decolorized area at a target size and at a target location. Coating a solution having a high viscosity on a polarizer that moves rapidly prevents the solution from spreading to an unnecessary portion by reducing a relative velocity difference between the liquid generated during coating and the polarizer, and reduces the flow of the coating solution during a decoloring time after coating and before washing, and thus, a decoloring area having a target position or size may be formed.

The viscosity agent is not particularly limited as long as it has low reactivity and is capable of increasing the solution viscosity. According to one embodiment of the present disclosure, the viscosity agent comprises one or more selected from the group consisting of: polyvinyl alcohol-based resins, polyvinyl acetoacetate-based resins, acetoacetyl-modified polyvinyl alcohol-based resins, butenediol vinyl alcohol-based resins, polyethylene glycol-based resins, and polyacrylamide-based resins.

According to another embodiment, the viscosity agent may be included at 0.5 wt% to 30 wt% with respect to the total weight of the decoloring solution. Specifically, according to one embodiment of the present disclosure, the viscosity agent may be included at 2.5 wt% to 15 wt% with respect to the total weight of the decoloring solution. When the content of the viscosity agent is more than the above range, the viscosity becomes too high and washing is not effective, and when the content of the viscosity agent is too low, the viscosity is low, so that it is difficult to obtain a discolored region having a target shape and size due to diffusion and flow of liquid.

According to one embodiment of the present disclosure, the decolorizing solution may include 1 to 30 wt.% of a decolorizing agent, relative to the total weight; 0.5 to 30 wt% of a viscosity agent; and 40 to 70 weight percent water.

Meanwhile, the mechanism of depolarization by the decoloring of the present disclosure can be specifically described as follows.

Polyvinyl alcohol composites dyed with iodine and/or dichroic dyes are known to absorb light in the visible range of wavelengths ranging from 400nm to 800 nm. Herein, when the decoloring solution is brought into contact with the polarizer, iodine and/or dichroic dye, which absorbs light in a visible wavelength range, present in the polarizer is decomposed, the polarizer is decolored, and transmittance is increased and the degree of polarization is decreased.

For example, when an aqueous solution containing potassium hydroxide (KOH) (decolorant) is brought into contact with some regions of the iodine-dyed polyvinyl alcohol-based polarizer, iodine is decomposed in a series of processes, such as chemical equation 1 and chemical equation 2 below. Meanwhile, when undergoing a boric acid crosslinking process in the preparation of an iodine-dyed polyvinyl alcohol-based polarizer, potassium hydroxide directly decomposes boric acid, as described in the following chemical equation 3, eliminating the crosslinking effect through hydrogen bonds of polyvinyl alcohol and boric acid.

[ chemical equation 1]

12KOH+6I₂→2KIO₃+10KI+6H₂O

[ chemical equation 2]

I₅ ^-+IO₃ ^-+6H⁺→3I₂+3H₂O

I₃ ^-→I^-+I₂

[ chemical equation 3]

B(OH)₃+3KOH→K₃BO₃+3H₂O

In other words, iodine and/or iodide ion complexes such as I₅ ^-(620nm)、I₃ ^-(340nm) or I₂ ^-(460nm) decomposes by absorption of light in the visible region to produce I^-(300nm or less) or salt, and transmits most of the light in the visible region. Therefore, the polarization function is eliminated in the region (visible region) of about 400nm to 800nm, the total transmittance is increased in the polarizer, and the polarizer is made transparent. In other words, the polarization function can be eliminated by decomposing the aligned visible light-absorbing iodine complex into a monomolecular form that does not absorb visible light to produce polarized light in the polarizer.

According to an embodiment of the present disclosure, after the formation of the discoloring region, a step of washing using an alcohol or acid solution may be further included. When the decoloring solution remaining at the time of forming the decoloring area is not properly washed, the solution is diffused or remains on the polarizer, the decoloring area may be formed in an undesired size and shape, and it is difficult to form the decoloring area having a fine size.

In particular, alcohol may be suitably used because it is easily dried and thus easily removed, and does not affect the transmittance or polarization degree of the polarizer other than the discolored region. For example, although not limited thereto, the alcohol is preferably ethanol, methanol, propanol, butanol, isopropanol, or a mixture thereof. Further, with respect to the acid solution, the remaining decolorant, mostly basic, is removed while undergoing a neutralization reaction with the acid solution, and examples of the acid solution may include, but are not limited to, an aqueous acetic acid solution, an aqueous adipic acid solution, an aqueous boric acid solution, an aqueous phosphoric acid solution, an aqueous lactic acid solution, an aqueous sulfuric acid solution, an aqueous nitric acid solution, or a mixed solution thereof.

The washing may be carried out by the following procedure: the polarizer is immersed in the alcohol for 1 to 180 seconds, more preferably 3 to 30 seconds, or the alcohol or acid solution is coated on a local area decolorized by contacting with the decolorizing solution using a dispenser, an inkjet printer, or the like.

The method for manufacturing a polarizing plate including a decolored region according to one embodiment of the present disclosure includes washing with an alcohol or acid solution after using a decolorant, and as discussed above, an iodine compound, a salt, and the like formed from the decolorant are washed away and the content of iodine and an iodide ion complex in the decolored region is minimized. Thus, the residual iodine and iodide ion complexes in the decolorized area absorb less light and achieve a more transparent effect.

In the present disclosure, the edge roughness of the discolored part is 30 μm or less, preferably 20 μm or less, and advantageously 0 μm or more close to 0 μm.

In the present disclosure, the edge roughness means a sum of an outer maximum difference and an inner maximum difference in a circle at a line drawn every 2 degrees at any point of the discolored part. Fig. 4 schematically illustrates a method of measuring edge roughness. When the edge roughness is 30 μm or less, the discolored part shape becomes clearer. This value is advantageously 0 μm or closer to 0 μm. This means that when the discoloring part is placed on the lens part of a device such as a camera module, the function of the device is not degraded.

Fig. 6 and 7 show a case where photographing is performed using a polarizer having a decoloring section satisfying an edge roughness of 30 μm or less in a lens and a case where photographing is performed using a polarizer having a decoloring section having an edge roughness of more than 30 μm in a lens, respectively. When fig. 6 and 7 are compared, it can be determined that, in an image taken using a polarizer having a discolored portion satisfying an edge roughness of more than 30 μm in a lens, an image corresponding to a side surface (a portion indicated as a circle in fig. 6 and 7) is blurred.

In the present disclosure, the edge roughness of the perforated portion of the mask film is 30 μm or less, preferably 20 μm or less, advantageously 0 μm or more close to 0 μm. The edge roughness of the punched portion of the mask film means the sum of the outer maximum difference and the inner maximum difference in a circle at a line drawn every 2 degrees at an arbitrary point of the punched portion. In other words, when the edge roughness of the perforated portion of the mask film is 0 μm or more close to 0 μm, the edge roughness of the decolored portion of the polarizer more easily becomes 30 μm or less when the decoloring process of the polarizer is performed using the mask film. The use of such a polarizer in the lens portion of a device such as a camera module does not degrade the functionality of the device.

According to an embodiment of the present disclosure, after the discoloring region is formed, a step of forming an optical layer on at least one surface of the polarizer may be further included. Herein, the optical layer may be a polymer film layer such as a protective film or a retardation film, may be a functional film layer such as a brightness enhancement film, and may be a functional layer such as a hard coat layer, an anti-reflection layer, or an adhesive layer.

More specifically, according to one embodiment of the present disclosure, an optical layer is formed on the other surface of the polarizer. In other words, the optical layer is formed on the surface of the polarizer on which the protective film and the release film are not provided.

Meanwhile, the optical layer may be directly attached or formed on a surface of the polyvinyl alcohol-based polarizer, or may also be attached on a protective film or other coating attached on one surface of the polyvinyl alcohol-based polarizer.

The method of forming the optical layer may be different according to the type of the optical layer to be formed, for example, a method of forming the optical layer known in the art may be used, and the method is not particularly limited.

According to an embodiment of the present disclosure, after the discoloring region is formed, a step of removing the release film may be further included. The removal of the release film may be performed using a method of peeling the release film from the protective film. More specifically, the removal of the release film may be performed using a method of peeling the release film from the protective film using a peeling roller or the like.

The release film plays a role of suppressing the occurrence of sagging (stretching in the protective film direction) in the formation of the discoloring region, and is preferably removed after the formation of the discoloring region.

The discolored region of the present disclosure may mean a non-polarized part. Therefore, a polarizer having a non-polarizing portion can be manufactured using the mask film.

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

The polarizer may have a thickness of 1 μm or more, 3 μm or more, 5 μm or more, 7 μm or more, 10 μm or more, or 20 μm or more. Meanwhile, the thickness of the polarizer may be 30 μm or less, preferably 25 μm or less.

The decoloring section in the present specification may be used as a non-polarizing section. In other words, a polarizer having a non-polarizing portion may be manufactured using the mask film. The polarizer of the present disclosure as described above may be used to manufacture a polarizing plate.

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

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

As the protective film of the polarizer, those known in the art can be used, for example, cellulose-based resins such as diacetyl cellulose or triacetyl cellulose; a (meth) acryloyl group-based resin; a cycloolefin-based resin; olefin-based resins such as polypropylene; ester-based resins such as polyethylene terephthalate-based resins; a polyamide-based resin; a polycarbonate-based resin; or a copolymer resin thereof, however, the protective film is not limited thereto.

The polarizing plate manufactured using the manufacturing method of the present disclosure includes: a polarizer having a non-polarizing portion; and a polarizing plate protective film on at least one surface of the polarizer.

In one embodiment of the present disclosure, there is provided a polarizing plate, wherein the polarizer has at least one discolored region having a monomer transmittance (single body transmittance) of 80% or more and a polarization degree of 10% or less in a wavelength range of 400nm to 800nm, and the maximum sag depth of the discolored region is 10 μm or less.

According to one embodiment of the present disclosure, the area of the at least one discoloration region may be greater than or equal to 0.5mm²And less than or equal to 500mm²Preferably greater than or equal to 0.5mm²And less than or equal to 200mm²。

According to the disclosureIn one embodiment, a polarizing plate including a non-polarizing portion having a size of 0.5mm or more may be provided²And less than or equal to 500mm²And the edge roughness of the non-polarizing portion is 30 μm or less.

In the present disclosure, the sag means a sag in a protective film direction occurring when a polyvinyl alcohol (PVA) -based polarizer is brought into contact with a decoloring solution.

Specifically, this means that the degree of sagging is small as the depth of sagging is shallow, and since the deformation of appearance in the polarizing plate is minimized, there is an advantage that the adhesive is uniformly applied when the protective film or the like is laminated on the other surface. Therefore, when a polarizing plate having a structure including protective films on both surfaces of a polarizer is manufactured, the occurrence of defects can be reduced.

Further, there is an advantage in that since the sag depth is shallow, a polarizing plate having an improved appearance can be provided.

According to one embodiment of the present disclosure, the maximum sag depth of the discolored region may be 8 μm or less, 7 μm or less, or 6 μm or less.

The sag depth can be measured using a white light three-dimensional measuring device (optical profiler) or a Confocal Laser Scanning Microscope (CLSM).

The sag depth may mean a value obtained by subtracting a minimum value from a maximum value of a distance between a surface of the polarizer facing the protective film and a surface opposite to the surface facing the protective film. Further, the sag depth may mean a difference in height between a discolored region and an undecolorized region on the surface of the protective film when the polarizing plate is placed on a flat surface.

The polarizing plate according to one embodiment of the present disclosure has a decolored region in which a monomer transmittance in a wavelength range of 400nm to 800nm included in a visible region is 80% or more, an arithmetic average roughness (Ra) is 200nm or less, and a degree of polarization is 10% or less.

As described above, the decoloring area refers to an area formed by undergoing a process of selectively contacting a decoloring solution with some areas of a polyvinyl alcohol-based polarizer dyed with iodine and/or dichroic dyes.

The monomer transmittance of the decolored region in a wavelength range of 400nm to 800nm, more preferably 450nm to 750nm as a visible region is 80% or more, preferably 90% or more, more preferably 92% or more. Further, the degree of polarization of the decolored region is 10% or less, more preferably 5% or less. Since the discolored region has a higher monomer transmittance and a lower degree of polarization, visibility is enhanced, and performance and image quality of the camera lens to be located in the region can be further enhanced.

According to one embodiment of the present disclosure, the monomer transmittance of the region of the polarizing plate other than the decolored region is preferably 40% to 47%, more preferably 42% to 47%. Further, the degree of polarization of the region of the polarizing plate other than the discolored region is preferably 99% or more. This is due to the fact that the remaining region other than the discolored region needs to exhibit excellent optical characteristics shown in the above range by exerting a main function as a polarizing plate.

According to an embodiment of the present disclosure, the arithmetic average roughness (Ra) of the discolored region may be 200nm or less, and specifically, the arithmetic average roughness (Ra) may be 100nm or less, or 80nm or less, and more specifically, 50nm or less.

According to an embodiment of the present disclosure, the root mean square roughness (Rq) of the discolored region may be 200nm or less, specifically, the root mean square roughness (Rq) may be 100nm or less, or 80nm or less, more specifically, 50nm or less.

The arithmetic average roughness (Ra) is a value defined in JIS B0601-1994, and represents a value obtained by: a reference length is extracted from the roughness curve in the direction of the mean line, the absolute values of the deviations from the mean line of the extracted portion to the measurement curve are summed, and the result is averaged. The root mean square roughness (Rq) is defined in JIS B0601-2001. Arithmetic mean roughness (Ra) and root mean square roughness (Rq) were measured using an optical profiler (nanosiew E1000, Nanosystem co., Ltd.).

When the polarizer surface roughness increases, haze generally increases by refraction and reflection of light. When the roughness of the discolored region satisfies the above range, the haze is sufficiently low and clear visibility is obtained.

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

According to one embodiment of the present disclosure, the iodine and/or dichroic dye content of the decolourized areas is from 0.1 to 0.5 wt%, preferably from 0.1 to 0.35 wt%. This is due to the fact that: as discussed above, iodine present in the form of a complex on the polarizer by the reaction of the decolorant with iodine is washed away, causing a significant decrease in the content of iodine and/or dichroic dye, and thus, the transmittance is greatly enhanced.

In contrast, according to one embodiment of the present disclosure, the iodine and/or dichroic dye content of the region other than the discolored region is 1 to 4% by weight, preferably 2 to 4% by weight.

Herein, the iodine and/or dichroic dye content is measured using an optical x-ray analyzer (manufactured by Rigaku Corporation, trade name "ZSX Primus II"). In the present disclosure, each 19.2mm was measured using a polarizer sheet type sample having dimensions of 40mm × 40mm and a thickness of 12 μm³Average weight% of volume.

According to another embodiment, the discolored region may be 0.005% to 40% with respect to the total area of the polarizing plate.

The polarizing plate according to the present disclosure as described above may be used to manufacture an image display device.

More specifically, the present disclosure provides an image display device including: a display panel; and a polarizing plate according to the above embodiment attached to one surface or both surfaces of the display panel.

The display panel may include a liquid crystal panel, a plasma panel, and an organic light emitting panel, and thus, the image display device may include a liquid crystal display device (LCD), a Plasma Display Panel (PDP), and an Organic Light Emitting Diode (OLED).

More specifically, the image display device may be a liquid crystal display device including a liquid crystal panel and polarizing plates each disposed on both surfaces of the liquid crystal panel, and herein, at least one of the polarizing plates may be a polarizing plate including the polarizer according to one embodiment of the present disclosure described above. In other words, the polarizing plate includes a polyvinyl alcohol-based polarizer dyed with iodine and/or a dichroic dye, and a protective film disposed on at least one surface of the polyvinyl alcohol-based polarizer, wherein a decolored region having an arithmetic average roughness (Ra) of 200nm or less, a degree of polarization of 10% or less, and a sag of 10 μm or less is locally included, the monomer transmittance of which is 80% or more in a wavelength range of 400nm to 800 nm.

Herein, the type of the liquid crystal panel included in the liquid crystal display device is not particularly limited. For example, all known panels including the following may be used without limitation of the type: panels using a passive matrix method, such as a Twisted Nematic (TN) type, a Super Twisted Nematic (STN) type, a ferroelectric (F) type, or a Polymer Dispersed (PD) type; a panel using an active matrix method, such as a two-terminal type or a three-terminal type; and an in-plane switching (IPS) panel and a Vertical Alignment (VA) type panel. In addition, other configurations forming the liquid crystal display device, such as types of upper and lower substrates (e.g., a color filter substrate or an array substrate), are also not particularly limited, and configurations known in the art may be employed without limitation.

According to an embodiment of the present disclosure, the image display device may be an image display device further including a camera module disposed in the decoloring area of the polarizing plate. An effect of enhancing visibility of the camera lens unit can be obtained by placing the camera module on the decoloring area in which transmittance in the visible region is enhanced and the degree of polarization is eliminated, and an effect of improving the appearance can also be obtained by including the polarizing plate that suppresses sagging of the decoloring area.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, the present disclosure will be described in detail with reference to examples. However, the embodiments according to the present disclosure may be modified into various other forms, and the scope of the present disclosure should not be construed as being limited to the embodiments described below. The embodiments of the present disclosure are provided to more fully describe the present disclosure to those of ordinary skill in the art.

< preparation of adhesive >

a. Preparation of copolymer resin (A)

To a 1L reactor having a nitrogen reflux and equipped with a cooling device to easily control the temperature, 94 parts by weight of butyl acrylate, 1 part by weight of 2-hydroxyethyl (meth) acrylate, and 5 parts by weight of acrylic acid were introduced, relative to 100 parts by weight of the entire reaction mass. Then, the reactor was purged with nitrogen for 20 minutes to remove oxygen in the reactor, and the temperature of the reactor was maintained at 60 ℃. Thereafter, 0.03 parts by weight of azobisisobutyronitrile (reaction initiator) diluted in ethyl acetate at a concentration of 50% was injected thereto. The resultant was reacted for 8 hours to obtain a final acryl-based polymer (a).

b. Preparation of copolymer resin (B)

Into a 1L reactor having a nitrogen reflux and equipped with a cooling device to easily control the temperature, a monomer mixture formed of 91 parts by weight of butyl acrylate, 1 part by weight of 2-hydroxyethyl (meth) acrylate, 4 parts by weight of acrylic acid and 4 parts by weight of methacryloyl polymethyl methacrylate was introduced with respect to 100 parts by weight of the entire reaction mass, and 100 parts by weight of ethyl acetate was introduced thereto as a solvent. Then, the reactor was purged with nitrogen for 20 minutes to remove oxygen in the reactor, and the temperature of the reactor was maintained at 65 ℃. Thereafter, 0.03 parts by weight of azobisisobutyronitrile (reaction initiator) diluted in ethyl acetate at a concentration of 50% was injected thereto, and the resultant was reacted for 8 hours to obtain an acryl-based polymer material (B).

c. Mixing

A toluene diisocyanate adduct of trimethylolpropane (isocyanate-based crosslinking agent) diluted to 50% in an ethyl acetate solution was introduced in a small amount with respect to 100 parts by weight of a copolymer obtained by mixing the acryl-based copolymer a and B obtained by the above copolymerization process in a weight ratio of 9:1 (weight ratio of a: B) to prepare an adhesive. The modulus of the adhesive can be adjusted according to the content of the crosslinking agent.

< production of polarizer >

< preparation example >

A polyvinyl alcohol-based film (Mitsubishi Chemical Corporation (formerly Nippon Synthetic Chemical Industry co., Ltd.), grade M3000, thickness 30 μ M) was subjected to a swelling process for 15 seconds in a pure water solution at 25 c, and then to a dyeing process for 60 seconds in an iodine solution at 25 c at a concentration of 0.2 wt%. Thereafter, the resultant was subjected to a washing process in a 45 ℃ solution with 1 wt% boric acid for 30 seconds, and then to a six-fold stretching process in a 52 ℃ solution with 2.5 wt% boric acid. Further, after the stretching process, the resultant was subjected to a complementary color process in a 5 wt% KI solution, and then dried in an oven at 60 ℃ for 5 minutes to prepare a polarizer having a thickness of 12 μm.

< production of polarizing plate having locally discolored region >

a. Preparation example 1

On a PET protective film having a thickness of 50 μm measured using the measurement method described in the present specification, an acryl-based adhesive was coated to a thickness of 6 μm to form an adhesive layer, and a 15 μm PET release film was laminated on the adhesive layer to prepare a mask film. Thereafter, CO is used₂The laser was passed through holes (punched portions) having a diameter of 3mm at intervals of 30cm on the mask film at an output of 10W and a pulse repetition rate of 20 kHz. Thereafter, the release film was removed from the perforated mask film, and laminated on both surfaces of the polarizer manufactured in the preparation example, after decoloring a portion coinciding with the holes (perforated portion) of the mask film by dipping in a 50 ℃ solution having 10 wt% KOH for 15 seconds, the resultant was neutralized by dipping in a 50 ℃ aqueous solution having 5 wt% citric acid for 10 seconds, and then dried at 60 ℃ for 5 minutes. Thereafter, the mask film was removed, and on both removed surfaces, TAC protective films were laminated using an adhesive to manufacture a polarizing plate having a local discolored part.

b. Preparation examples 2 to 5

A polarizing plate having a partially decolored region was manufactured in the same manner as in preparation example 1, except that adhesive layers were formed by applying an adhesive to thicknesses of 10 μm, 15 μm, 30 μm, and 80 μm, respectively.

c. Preparation examples 6 to 10

A polarizing plate having a local discolored region was manufactured in the same manner as in preparation example 1, except that adhesive layers were formed by applying an adhesive to thicknesses of 3 μm, 5 μm, 100 μm, 150 μm, and 210 μm, respectively.

d. Preparation examples 11 to 20

A polarizing plate having a local discolored region was manufactured in the same manner as in preparation example 1, except that the release film was removed from the perforated mask film and laminated on one surface of the polarizer manufactured in preparation example, discoloring was performed on a portion of the polarizing plate coinciding with the holes (perforated portions) of the mask film by dipping in a 50 ℃ solution having 10 wt% KOH for 15 seconds, and adhesive layers were formed by applying adhesives to thicknesses of 3 μm, 5 μm, 6 μm, 10 μm, 15 μm, 30 μm, 80 μm, 100 μm, 150 μm, and 210 μm, respectively.

< Experimental example >

The time taken for decoloring when the polarizing plate corresponding to each of preparation examples 1 to 20 was manufactured was measured. As for the time taken for decoloring, the time at which the transmittance of the decoloring section reaches 80% or more is measured as the time at which the decoloring is completed.

The edge roughness was measured by calculating the sum of the outer maximum difference and the inner maximum difference in a circle at a line drawn every 2 degrees at an arbitrary point corresponding to the discolored portion of each of the polarizing plates of preparation examples 1 to 20.

The measured values are described in table 1 below. Preparation examples 1 to 5 correspond to examples 1 to 5, respectively, and preparation examples 6 to 17 correspond to comparative examples 1 to 15, respectively.

[ Table 1]

It was confirmed that the time taken for decoloring was shorter when the mask films were laminated on both surfaces of the polarizer and decolored than when the mask films were laminated on one surface of the polarizer. Further, when the thickness of the adhesive is less than 6 μm, the edge roughness is measured to be greater than 1000 μm since the adhesive is transferred to the polarizer surface when the mask film is removed after the decoloring reaction, and when the thickness is greater than 80 μm, the edge roughness is greater than 30 μm since the adhesive slips as shown in fig. 5 or the like during mask punching. In other words, it was determined by examples 1 to 5 that the value of the edge roughness was 30 μm or less while reducing the time taken for decoloring only when the thickness of the adhesive was 6 to 30 μm and the mask films were laminated on both surfaces of the polarizer. This means that a polarizing plate having an appropriate non-polarizing portion, which does not degrade the function of a device such as a camera module when the discoloring portion is placed on the lens portion of the device, can be manufactured in a shorter period of time.