Polarizing plate laminate and method for manufacturing the same

Abstract

A polarizing plate laminate according to one embodiment of the present application comprises a polarizing plate; a first adhesive layer and a first separate film provided on one side of the polarizing plate; and a second adhesive layer and a second separate film provided on the other side of the polarizing plate, wherein the total thickness of the second separate film is more than 75 μm and not more than 150 μm.

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2019-0137106, filed with the Korean Intellectual Property Office on October 31, 2019, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to a polarizing plate laminate and a method for producing the same. [Background technology]

[0003] Liquid crystal display devices are one type of flat panel display that are widely used in a wide range of electronic devices, from small portable electronic devices such as mobile phones to large electronic devices such as personal computers and televisions, and their applications are expanding.

[0004] As the use of display devices expands, the locations and positions of display devices are becoming more diverse, but flat panel displays have a problem in that a clear image cannot be obtained when viewed from a direction other than the front of the display. In particular, in the case of in-vehicle displays, a problem occurs in that a clear image cannot be obtained in the driver's field of vision because the display position and the driver's line of sight are not parallel.

[0005] Therefore, in order to solve these problems, there is a need to develop a display device that can improve the viewing angle and contrast ratio. Summary of the Invention [Problem to be solved by the invention]

[0006] The present application seeks to provide a polarizing plate laminate and a method for manufacturing the same. [Means for solving the problem]

[0007] The polarizing plate laminate according to one embodiment of the present application includes a second separate film having a total thickness of more than 75 μm and not more than 150 μm, thereby preventing defects such as deflection of the polarizing plate during the process of bonding the polarizing plate to the liquid crystal panel or optical film of a liquid crystal display device.

[0008] This makes it possible to suppress the phenomenon in which bubbles may be generated at the bonding surface between the liquid crystal panel or optical film of the liquid crystal display device and the polarizing plate during the bonding process. [Effects of the Invention]

[0009] The polarizing plate laminate according to one embodiment of the present application includes a second separate film having a total thickness of more than 75 μm and not more than 150 μm, thereby preventing defects such as deflection of the polarizing plate during the process of bonding the polarizing plate to the liquid crystal panel or optical film of a liquid crystal display device.

[0010] This makes it possible to suppress the phenomenon in which bubbles may be generated at the bonding surface between the liquid crystal panel or optical film of the liquid crystal display device and the polarizing plate during the bonding process. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram schematically illustrating a polarizing plate laminate according to an embodiment of the present application. [Figure 2] 1 is a diagram schematically illustrating a polarizing plate laminate according to an embodiment of the present application. [Figure 3] FIG. 2 is a diagram showing the results of laminating an optical film and a polarizing plate according to Example 1 and Comparative Example 1 of the present application. [Figure 4] FIG. 1 is a diagram schematically illustrating the structure of a conventional polarizing plate. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present application will be described below. However, the embodiments of the present application can be modified in various different forms, and the scope of the present application is not limited to the embodiments described below. Furthermore, the embodiments of the present application are provided to more fully explain the present application to those skilled in the art.

[0013] Typically, a manufacturing process for a display device includes a process of bonding a polarizer to a liquid crystal panel or optical film of a liquid crystal display device. In the conventional process of bonding a polarizer to a liquid crystal panel or optical film of a liquid crystal display device, defects such as deflection of the polarizer can occur between a roll operating for the bonding process and a table on which the polarizer is placed. Therefore, during the process of bonding a liquid crystal panel or optical film of a liquid crystal display device to a polarizer, persistent air bubbles can occur at the bonding surface, resulting in persistent defects and making mass production impossible.

[0014] Therefore, in the present application, an attempt is made to suppress the generation of bubbles that may occur due to bending of the polarizing plate in the process of bonding the polarizing plate to the liquid crystal panel or optical film of the liquid crystal display device.

[0015] A polarizing plate laminate according to one embodiment of the present application comprises a polarizing plate; a first adhesive layer and a first separate film provided on one side of the polarizing plate; and a second adhesive layer and a second separate film provided on the other side of the polarizing plate, wherein the total thickness of the second separate film is more than 75 μm and not more than 150 μm.

[0016] In addition, a method for manufacturing a display device according to one embodiment of the present application includes the steps of applying a first adhesive layer to one side of a polarizing plate and applying a second adhesive layer to the other side; and laminating a first separate film on the first adhesive layer and a second separate film on the second adhesive layer, wherein the total thickness of the second separate film is more than 75 μm and not more than 150 μm.

[0017] In one embodiment of the present application, the first and second separate films are films that are temporarily attached to protect the surface of the polarizing plate until it is bonded to a liquid crystal panel or other optical member.

[0018] The first separate film may have a thickness of 10 μm to 75 μm.

[0019] The second separate film may have a single-layer structure or a multi-layer structure. The total thickness of the second separate film may be more than 75 μm and not more than 150 μm, may be 80 μm to 150 μm, or may be 90 μm to 140 μm. If the total thickness of the second separate film is 75 μm or less, defects such as deflection of the polarizing plate may occur during the bonding process between the liquid crystal panel or optical film of the liquid crystal display device and the polarizing plate. If the total thickness of the second separate film is more than 150 μm, defects such as deflection of the polarizing plate may occur during the peeling process of the second separate film. Therefore, if the total thickness of the second separate film is more than 75 μm and not more than 150 μm, defects such as deflection of the polarizing plate may be effectively prevented during the bonding process between the liquid crystal panel or optical film of the liquid crystal display device and the polarizing plate.

[0020] The second separate film may have a single layer structure or a two-layer structure. When the second separate film has a two-layer structure, the second separate film (A) that comes into direct contact with the polarizing plate may be a separate film that does not have adhesive properties on its surface, and the second separate film (B) that does not come into direct contact with the polarizing plate may be a separate film that has adhesive properties on its surface that will be bonded to the second separate film (A).

[0021] The first and second separate films may each contain one or more of a polyethylene-based resin such as polyethylene; a polypropylene-based resin such as polypropylene; a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate; and a polycarbonate-based resin.

[0022] In one embodiment of the present application, a first adhesive layer is provided between the polarizing plate and the first separate film, and a second adhesive layer is provided between the polarizing plate and the second separate film, so that the first separate film can be attached to one side of the polarizing plate by the first adhesive layer applied to the polarizing plate, and the second separate film can be attached to the other side of the polarizing plate by the second adhesive layer applied to the other side of the polarizing plate.

[0023] The first and second pressure-sensitive adhesive layers may contain a general-purpose pressure-sensitive adhesive, and more specifically, may be composed of a pressure-sensitive adhesive composition whose main component is a resin such as a (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resin. Among these, a pressure-sensitive adhesive composition whose base polymer is a (meth)acrylic resin that is excellent in transparency, weather resistance, heat resistance, etc. is preferred. The pressure-sensitive adhesive composition may be an active energy ray-curable or thermosetting type.

[0024] In one embodiment of the present application, the step of laminating the first and second separate films on the polarizing plate coated with the first and second adhesive layers may be performed by a roll-to-roll process, and the step of attaching the first and second separate films to the polarizing plate may be performed by preparing the corresponding products wound on rolls and then attaching them using a lamination roll.

[0025] A polarizer laminate according to one embodiment of the present application is schematically shown in Figures 1 and 2 below. More specifically, Figure 1 below shows a polarizer laminate including a first adhesive layer 20 and a first separate film 30 provided on one side of a polarizer 10, and a second adhesive layer 40 and a second separate film 50 provided on the other side of the polarizer 10. In this case, the total thickness of the second separate film 50 is more than 75 μm and 150 μm or less. Also, Figure 2 below shows a polarizer laminate in which the second separate film 50 has a two-layer structure.

[0026] In one embodiment of the present application, the region where the second separate film is provided may be a region where a liquid crystal panel or an optical film of a liquid crystal display device is located. That is, a liquid crystal display device manufactured using the polarizer laminate according to one embodiment of the present application can be manufactured by removing the second separate film of the polarizer laminate and attaching a liquid crystal panel or an optical film to the surface of the polarizer laminate from which the second separate film has been removed.

[0027] The structure of a conventional polarizer is schematically shown in Figure 4. As shown in Figure 4, the conventional polarizer includes a polarizer 10, a protective film 60 provided on one side of the polarizer 10, and a separate film 70 provided on the other side of the polarizer 10. The thickness of the protective film 60 of the conventional polarizer is about 50 μm to 60 μm, and the protective film 60 plays a role in stably controlling curl of the polarizer.

[0028] However, in one embodiment of the polarizing plate laminate of the present application, the thickness of the second separate film provided on the opposite side of the joining surface is adjusted to more than 75 μm and not more than 150 μm in order to prevent the occurrence of bubbles at the joining surface during the process of bonding the polarizing plate to the liquid crystal panel or optical film of the liquid crystal display device, and the structure and purpose of the polarizing plate laminate are different from those of conventional polarizing plates.

[0029] A method for manufacturing a polarizing plate laminate according to one embodiment of the present application may further include the steps of removing the first separate film; and bonding the polarizing plate to one surface of the liquid crystal panel or optical film of a liquid crystal display device so that the surface of the polarizing plate laminate from which the first separate film has been removed is bonded to one surface of the liquid crystal panel or optical film.

[0030] The optical film may include, but is not limited to, one or more of an antiglare film, a hard coating film, an anti-reflection film, and an AGLR (Anti-Glare & Low-Reflection) film. The optical film may be manufactured using a method known in the art. The optical film may also be a polycarbonate film.

[0031] The method for manufacturing a polarizing plate laminate according to an embodiment of the present application may further include a step of removing the second separate film after the step of bonding the polarizing plate to the liquid crystal panel or optical film of the liquid crystal display device. After the step of removing the second separate film, one or more liquid crystal panels, optical films, etc. known in the art may be further bonded, or may be provided on the liquid crystal panel, optical film, etc. known in the art.

[0032] As described above, conventionally, during the process of bonding a polarizer to a liquid crystal panel or optical film of an LCD device, stress occurs due to deflection of the polarizer, and air bubbles can occur when the bent portion of the film is bonded to the liquid crystal panel or optical film due to suction removal. However, according to one embodiment of the present application, by using a polarizer laminate including a second separate film having a total thickness of more than 75 μm and not more than 150 μm, defects such as deflection of the polarizer can be prevented during the process of bonding a polarizer to a liquid crystal panel or optical film of an LCD device.

[0033] In one embodiment of the present application, the polarizing plate may include a polarizer and a protective film on at least one surface of the polarizer.

[0034] The polarizer protective film may be, but is not limited to, a triacetyl cellulose (TAC) film, a cycloolefin polymer (COP), an acrylic film, or the like.

[0035] The polarizer is not particularly limited, and polarizers well known in the art, such as a film made of polyvinyl alcohol (PVA) containing iodine or a dichroic dye, can be used.

[0036] Polarizers exhibit the ability to extract only light vibrating in one direction from incident light vibrating in multiple directions. This characteristic can be achieved by stretching iodine-absorbed polyvinyl alcohol (PVA) under strong tension. For example, a polarizer can be fabricated through a swelling step in which a PVA film is immersed in an aqueous solution to swell, a dyeing step in which the swollen PVA film is dyed with a dichroic dye that imparts polarizing properties, a stretching step in which the dyed PVA film is stretched to align the dichroic dye in the stretching direction, and a complementary color step in which the color of the stretched PVA film is corrected. However, the polarizing plate of the present application is not limited thereto.

[0037] In addition, another embodiment of the present application provides a liquid crystal display device manufactured using the polarizer laminate according to the present application. The liquid crystal display device may include any configuration known in the art, except for being manufactured using the polarizer laminate according to the embodiment of the present application.

[0038] For example, a liquid crystal display device according to an embodiment of the present application may include a liquid crystal panel; a first polarizer provided on the viewing side of the liquid crystal panel; a second polarizer provided on the side opposite the viewing side of the liquid crystal panel; and a backlight unit provided on the side of the second polarizer opposite the surface facing the liquid crystal panel. In this case, the first polarizer or the second polarizer may be the polarizer laminate according to an embodiment of the present application. In addition, the liquid crystal panel may further include a separate polarizer other than the polarizer laminate according to an embodiment of the present application, and in this case, the additional polarizer may be a polarizer known in the art.

[0039] In this application, the term "viewing side" refers to a surface or direction that faces a viewer when the polarizing plate is mounted in a display device such as a liquid crystal display device. Conversely, the term "opposite side to the viewing side" refers to a surface or direction that faces the opposite side to the viewer, i.e., a backlight unit, when the polarizing plate is mounted in a display device such as a liquid crystal display device.

[0040] In one embodiment of the present application, the liquid crystal display device may be an in-vehicle liquid crystal display device. [Example]

[0041] The following examples illustrate the embodiments described herein, but are not intended to limit the scope of the embodiments.

[0042] <Example> Example 1 After applying an adhesive (LG Chemical, high-durability adhesive) to both sides of a polarizing plate (LG Chemical, high-durability polarizing plate), a first separate film (polyethylene terephthalate, PET) was laminated on one side of the polarizing plate using a roll-to-roll process, and a second separate film (polyethylene terephthalate, PET) was laminated on the other side. The first separate film was a 38 μm thick monolayer film manufactured by Mitsubishi Corporation, and the second separate film was a 93 μm thick monolayer film manufactured by LG Chemical.

[0043] After removing the first separate film from the polarizing plate, the polycarbonate film and the polarizing plate were bonded to one surface of the polycarbonate film (Shinetec) so that the surface of the polarizing plate from which the first separate film had been removed was bonded (using bonding equipment manufactured by DaeChang Co., Ltd.). The bonding speed during the bonding process was 400 mm / min.

[0044] <Example 2> The same procedure as in Example 1 was carried out except that the second separate film was a two-layer film formed by laminating a 38 μm-thick monolayer film (Mitsubishi) and a 93 μm-thick monolayer film (LG Chem) together to form a total thickness of 131 μm.

[0045] Example 3 The same procedure as in Example 1 was carried out except that the second separate film was a two-layer film formed by laminating a 50 μm-thick monolayer film (Mitsubishi) and a 93 μm-thick monolayer film (LG Chem) together to form a total thickness of 143 μm.

[0046] <Comparative Example 1> The same procedure as in Example 1 was carried out, except that a single-layer film (Mitsubishi) having a thickness of 38 μm was used as the second separate film.

[0047] <Comparative Example 2> The same procedure as in Example 1 was carried out, except that a single-layer film (Mitsubishi) having a thickness of 50 μm was used as the second separate film.

[0048] <Comparative Example 3> The same procedure as in Example 1 was carried out except that a single layer film (Toray) having a thickness of 75 μm was used as the second separate film.

[0049] <Comparative Example 4> The same procedure as in Example 1 was carried out, except that the second separate film was a two-layer film made by laminating a 75 μm thick monolayer film (Toray) and a 93 μm thick monolayer film (LG Chem) together to form a total thickness of 168 μm.

[0050] <Experimental Example> After the step of laminating the polarizing plate and polycarbonate film according to the Examples and Comparative Examples, the presence or absence of defects on the bonding surface between the polarizing plate and polycarbonate film was evaluated, and the results are shown in Table 1 below. The results of laminating the optical film and polarizing plate according to Example 1 and Comparative Example 1 are shown in Figure 3 below. The evaluation results in Table 1 below were evaluated based on the presence or absence of defects such as bubbles when the bonding surface between the polarizing plate and polycarbonate film was visually inspected.

[0051] [Table 1]

[0052] As shown in the results of Figure 3 below, when the optical film and polarizing plate were bonded together according to Example 1, no air bubbles were generated at the bonding surface between the optical film and polarizing plate. However, when the optical film and polarizing plate were bonded together according to Comparative Example 1, it was confirmed that the polarizing plate bent during the bonding process, resulting in the generation of air bubbles at the bonding surface between the optical film and polarizing plate.

[0053] Therefore, the polarizing plate laminate of one embodiment of the present application includes a second separate film having a total thickness of more than 75 μm and not more than 150 μm, thereby preventing defects such as deflection of the polarizing plate during the process of bonding the polarizing plate to the liquid crystal panel or optical film of the liquid crystal display device.

[0054] This makes it possible to suppress the phenomenon in which bubbles may be generated at the bonding surface between the liquid crystal panel or optical film of the liquid crystal display device and the polarizing plate during the bonding process. [Explanation of symbols]

[0055] 10: Polarizing plate 20: 1st adhesive layer 30: First separate film 40:Second adhesive layer 50: Second separate film 60: Protective film 70: Separate film

Claims

1. Polarizer; a first pressure-sensitive adhesive layer and a first separate film provided on one surface of the polarizing plate; and a second adhesive layer and a second separate film provided on the other side of the polarizing plate; The total thickness of the second separate film is 131 μm or more and 143 μm or less, The first and second separate films each contain at least one of a polyethylene-based resin, a polypropylene-based resin, a polyester-based resin, and a polycarbonate-based resin, the second separate film has a two-layer structure in which a single-layer film is laminated, the surface on which the second separate film is provided is a surface on which a liquid crystal panel or an optical film of a liquid crystal display device is attached; A polarizing plate laminate, wherein the first separate film has a thickness of 10 μm to 75 μm.

2. applying a first adhesive layer to one side of a polarizing plate and a second adhesive layer to the other side; and The method includes a step of laminating a first separate film on the first adhesive layer and a second separate film on the second adhesive layer, The total thickness of the second separate film is 131 μm or more and 143 μm or less, The first and second separate films each contain at least one of a polyethylene-based resin, a polypropylene-based resin, a polyester-based resin, and a polycarbonate-based resin, the second separate film has a two-layer structure in which a single-layer film is laminated, the surface on which the second separate film is provided is a surface on which a liquid crystal panel or an optical film of a liquid crystal display device is attached; The method for producing a polarizing plate laminate, wherein the first separate film has a thickness of 10 μm to 75 μm.

3. The method of claim 2 , wherein the laminating of the first and second separate films is performed using a roll-to-roll process.

4. 4. The method for producing a polarizer laminate according to claim 2 or 3, further comprising the steps of: removing the first separate film; and bonding the polarizer to the liquid crystal panel or optical film of a liquid crystal display device so that the surface of the polarizer laminate from which the first separate film has been removed is bonded to one surface of the liquid crystal panel or optical film.

5. 5. The method for manufacturing a polarizer laminate according to claim 4, wherein the optical film comprises at least one of an antiglare film, a hard coating film, an anti-reflection film, and an AGLR (Anti-Glare & Low-Reflection) film.

6. The method for producing a polarizing plate laminate according to claim 4 or 5, wherein the optical film is a polycarbonate film.

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