KR20170010289A

KR20170010289A - Liquid crystal display device and method of manufacturing the same

Info

Publication number: KR20170010289A
Application number: KR1020150102077A
Authority: KR
Inventors: 이현필
Original assignee: 엘지디스플레이 주식회사
Priority date: 2015-07-18
Filing date: 2015-07-18
Publication date: 2017-01-26

Abstract

A liquid crystal display device and a method of manufacturing the same are provided. The liquid crystal display includes a substrate assembly, a cover glass, and an adhesive member. The substrate assembly includes a lower substrate and an upper substrate facing each other, and a lower substrate protrudes from one surface of the upper substrate in the pad region. The cover glass is opposed to the substrate assembly. The bonding member adheres the cover glass to the lower substrate on the lower substrate of the substrate assembly protruding from the pad region, so that the deformation of the lower substrate is minimized even if the distance between the cover glass and the lower substrate changes.

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal display device and a method of manufacturing the same,

The present invention relates to a liquid crystal display device and a method of manufacturing the same, and more particularly, to a liquid crystal display device with minimized light leakage and improved durability and a method of manufacturing the same.

BACKGROUND ART A liquid crystal display (LCD) is a display device that implements an image in such a manner that a light source is disposed under a liquid crystal and an electric field is applied to the liquid crystal to control the arrangement of liquid crystal to pass or block light generated in the light source . Since a liquid crystal display device has a thinner thickness and a clearer image quality than a cathode ray tube (CRT) display device, the liquid crystal display device is applied to a TV, a monitor, and the like, and is recently widely used as a display device of a portable terminal such as a smart phone or a tablet PC have.

Since the liquid crystal display implements an image by controlling the arrangement of the liquid crystals, it is necessary to keep the initial arrangement of the liquid crystals constant. If the arrangement of the initial liquid crystals is locally turned off, the arrangement of the liquid crystals can not be controlled as desired, resulting in unevenness on the screen or leakage of light between the misaligned liquid crystals. Accordingly, researches for analyzing the causes of light leakage in a liquid crystal display device and reducing light leakage are actively underway. In addition, since the liquid crystal display device is applied to a portable terminal such as a smart phone, a tablet PC and the like, the durability of the liquid crystal display device becomes important, and studies for improving the durability of the liquid crystal display device are actively underway.

There are various factors that cause light leakage in the liquid crystal display device and factors that reduce the durability. However, the lower substrate of the liquid crystal display device may be bent to generate light leakage, and the lower substrate of the liquid crystal display device may be easily damaged by the impact. Thus, the durability of the liquid crystal display device can be reduced. Particularly, light leakage frequently occurs at the edge of the display area adjacent to the pad area of the liquid crystal display device, and breakage of the lower substrate frequently occurs in the pad area of the liquid crystal display device. That is, the pad area of the liquid crystal display device is a region where a flexible printed circuit board (FPCB) contacts the panel of the liquid crystal display device, and the thin lower substrate of the liquid crystal display device is exposed alone. The thin lower substrate and the cover glass of the liquid crystal display device are bonded with an adhesive member. However, in general, since the bonding member is a rigid member having a large elastic modulus, it may cause bending of the lower substrate in the manufacturing process of the liquid crystal display device, and may cause light leakage. Further, the rigidity of the adhesive member is insufficient to buffer external impacts, so that the durability of the liquid crystal display device can be reduced.

Liquid crystal display devices (Japanese Patent Application No. 2002-257891)

The inventors of the present invention have recognized that the lower substrate of the pad region may be bent due to the rigidity of the adhesive member, thereby causing light leakage and reducing the durability of the liquid crystal display device. Reference is now made to Figs. 1A and 1B to describe this in more detail.

FIG. 1A is a schematic perspective view illustrating a light leakage phenomenon and a durability reduction phenomenon occurring in a liquid crystal display device. FIG. 1B is a schematic cross-sectional view taken along line I-I 'of FIG. 1A for explaining a light leakage phenomenon and a durability reduction phenomenon generated in a liquid crystal display device.

1A and 1B, a liquid crystal display 100 includes a substrate assembly 110 and a cover glass 130 that covers the substrate assembly 110 and includes a substrate assembly 110, a cover glass 130, Are bonded to each other using an optical adhesive (121). The substrate assembly 110 includes an upper substrate 111 and a lower substrate 112. The upper substrate 111 and the lower substrate 112 are bonded to each other with a sealant 113, 112 are arranged between the liquid crystal LC and the liquid crystal LC. The substrate assembly 110 receives signals from the display printed circuit board 140 and implements the images based on the received signals. The substrate assembly 110 is in contact with the display printed circuit board 140 in the pad area PA and the display printed circuit board 140 in the pad area PA contacts the lower substrate 111 of the substrate assembly 110 do. In addition, when the substrate assembly 110 includes a touch screen panel (TSP), a touch printed circuit board 150 for receiving a touch signal is formed on the lower portion of the substrate assembly 110 in the pad area PA. And is in contact with the substrate 111.

The display printed circuit board 140 and the touch printed circuit board 150 should be in contact with the wirings disposed on the lower substrate 111 of the substrate assembly 110. Thus, the upper substrate 112 can not be disposed on the lower substrate 111 of the pad region PA, and the lower substrate 111 is exposed alone in the pad region PA. Thus, the pad area PA of the substrate assembly 110 has a durability that is relatively weak compared to the non-pad area NPA.

An adhesive member 160 is disposed between the lower substrate 111 and the cover glass 130 of the pad area PA to reinforce the fragile durability of the pad area PA of the substrate assembly 110. [ However, since the adhesive member 160 is a rigid member for firmly adhering the cover glass 130 and the lower substrate 111, the adhesive member 160 is not deformed well. Particularly in the process of bonding the cover glass 130 and the substrate assembly 110 due to the rigidity of the adhesive member 160, a problem that the lower substrate 111 is bent often occurs, The light leakage of the liquid crystal display device 100 is caused. Also, since the rigidity of the adhesive member 160 is insufficient to buffer the impact applied to the lower substrate 111, the lower substrate 111 can be easily damaged by an external impact. To explain this in detail, reference is made to FIG.

1B, the substrate assembly 110 and the cover glass 130 are adhered by the optical adhesive member 121. The process of adhering the substrate assembly 110 to the cover glass 130 is as follows. First, after the dam member 122 is formed on the upper substrate 112, a composition for the optical bonding member for forming the optical bonding member 121 is applied on the upper substrate 112. [ In addition, a composition for an adhesive member for forming the adhesive member 160 is applied on the lower substrate 111 of the pad area PA. Here, the dam member 122 prevents the composition for the optical bonding member from overflowing when the composition for the optical bonding member is applied on the upper substrate 112, and before the composition for the optical bonding member is applied Cured. The cover glass 130 is then pressed onto the electrostatic chuck so that the cover glass 130 is aligned on the substrate assembly 110 and the composition for the adhesive member is brought into contact with the lower surface of the cover glass 130. In this case, since the contact surface between the composition for the adhesive member and the cover glass 130 should be maximized, the cover glass 130 is excessively pressed, and the dam member 122 is also partially compressed by the pressure.

Thereafter, with the cover glass 130 being pressed, the composition for the adhesive member is cured to form the adhesive member 160. The reason that the composition for the adhesive member is cured before the composition for the optical adhesive member is cured is that the adhesive member 160 is not aligned with the alignment between the cover glass 130 and the substrate assembly 110 until the composition for the optical adhesive member is cured it is necessary to maintain the alignment. Specifically, since the optical adhesive member 121 covers the active area in which the image is displayed in the non-pad area NPA, the optical adhesive member 121 and the cover glass 130 must be perfectly bonded, 121 and the cover glass 130, there should be no gap or air bubble. If there is a portion or bubble in the active region that is separated from the active region, the refractive index of the portion where bubbles are present or adhered away and the refractive index of the portion where the optical adhesive member 121 and the cover glass 130 are normally bonded are different from each other Therefore, the visibility of the liquid crystal display device 100 may be deteriorated. Therefore, a process for removing air bubbles between the composition for the optical bonding member and the cover glass 130 is necessarily performed before the composition for the optical bonding member is cured. However, alignment of the cover glass 130 and the substrate assembly 110 may be distorted in the process of removing air bubbles because the adhesive composition is weak before the composition for optical bonding members is cured. Therefore, a member capable of maintaining the alignment of the cover glass 130 and the substrate assembly 110 during the bubble removing process is required, and the adhesive member 160 performs this function. That is, the composition for the adhesive member is cured before the composition for the optical adhesive member is cured, and the adhesive member 160 bonds the cover glass 130 and the lower substrate 111 of the substrate assembly 110, The alignment of the cover glass 130 and the substrate assembly 110 can be maintained.

In this case, in order to maintain the alignment of the cover glass 130 and the substrate assembly 110, the adhesive member 160 needs to have a large elastic modulus and a small elongation. That is, the adhesive member 160 maintains a small elongation ratio so as to maintain the alignment between the cover glass 130 and the substrate assembly 110, and to keep the distance between the cover glass 130 and the substrate assembly 110 constant . The adhesive member 160 also has a large modulus of elasticity to return the cover glass 130 and the substrate assembly 110 to the initial alignment when the alignment between the cover glass 130 and the substrate assembly 110 is broken There is a need. If the adhesive member 160 has a large elongation, the alignment of the cover glass 130 and the substrate assembly 110 may be interrupted due to an external impact. If the alignment of the cover glass 130 and the substrate assembly 110 is not correct, the adhesive member 160 may be detached from the cover glass 130 and the substrate assembly 110 when the adhesive member 160 has a small elastic modulus. The alignment may not be returned to the initial state. Accordingly, the adhesive member 160 should have a large modulus of elasticity and small elongation that can maintain the alignment of the cover glass 130 and the substrate assembly 110. That is, the adhesive member 160 should have sufficient rigidity.

When the electrostatic chuck pressing the cover glass 130 to remove air bubbles between the cover glass 130 and the composition for the optical adhesive member is detached, the cover glass 130, due to the elastic force of the compressed dam member 122, Can be increased. However, since the adhesive member 160 adhered to the cover glass 130 and the lower substrate 111 is a rigid member, it has a fixed thickness. 1B, the adhesive member 160 can be lifted together with the cover glass 130, and the lower substrate 111 bonded to the adhesive member 160 can be raised, Is also elevated along the cover glass 130. As a result, the lower substrate 111 is bent in the pad area PA.

The bending of the lower substrate 111 in the pad region PA can locally change the arrangement of the liquid crystal LC in the non-pad region NPA. That is, the bending of the lower substrate 111 in the pad area PA can be continued to the non-pad area NPA, and the distance between the upper substrate 112 and the lower substrate 111 in the non- . The arrangement of some liquid crystals LC 'may be locally changed as the distance between the upper substrate 112 and the lower substrate 111 becomes nonuniform in the non-pad region NPA. Particularly, the probability that the arrangement of the liquid crystal LC 'is locally changed in the region adjacent to the pad region PA is high and the light leakage occurs between the different liquid crystal LC', so that the brightness of the liquid crystal display device 100 becomes uneven .

On the other hand, since the adhesive member 160 has a large elastic modulus and a small elongation, it may not be suitable for absorbing an external impact, and the impact applied to the lower substrate 111 in the pad region PA may be sufficiently buffered ). In addition, due to the bending of the lower substrate 111, stress is applied to the inside of the lower substrate 111, and the durability of the lower substrate 111 of the pad area PA can be reduced accordingly. That is, the lower substrate 111 of the pad area PA can be easily cracked even with a small impact, thereby reducing the durability of the substrate assembly 110.

As described above, the lower substrate 111 of the pad region PA can be deformed due to the rigidity of the adhesive member 160. [ Particularly, since the adhesive member 160 must keep the alignment of the cover glass 130 constant before the composition for the optical adhesive member is cured, the adhesive member 160 can maintain the excellent rigidity . On the other hand, since the cover glass 130 is bonded to the substrate assembly 110 by the optical bonding member after the composition for the optical bonding member is cured, the bonding member 160 does not require excellent rigidity. Rather, the excellent rigidity of the adhesive member 160 causes deformation of the lower substrate 111 of the substrate assembly 110, and light leakage can be generated by deformation of the lower substrate 111. Therefore, the adhesive member 160 needs to maintain sufficient rigidity until the composition for the optical adhesive member is cured, and then softened after the composition for the optical adhesive member is cured. Thus, the inventors of the present invention invented a liquid crystal display device including an adhesive member having excellent rigidity by a first-order reaction and having flexibility after a secondary reaction.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method of bonding a cover glass and a substrate assembly by applying an adhesive member that minimizes deformation of a lower substrate even when a distance between a cover glass and a lower substrate is changed, The present invention provides a liquid crystal display device and a method of manufacturing the same that minimize the bending of a lower substrate that may be generated in the process and minimize light leakage.

Another object of the present invention is to provide a composition for an optical bonding member having an elastic modulus and elongation suitable for maintaining alignment of a cover glass and a substrate assembly in a process of removing air bubbles between a cover glass and a composition for an optical adhesive member, There is provided a liquid crystal display device having improved productivity and durability by using an adhesive member having an elastic modulus and elongation suitable for minimizing deformation of a lower substrate and absorbing an impact applied to a lower substrate after cured .

The problems of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a liquid crystal display device including a substrate assembly, a cover glass, and an adhesive member. The substrate assembly includes a lower substrate and an upper substrate facing each other, and a lower substrate protrudes from one surface of the upper substrate in the pad region. The cover glass is opposed to the substrate assembly. The bonding member adheres the cover glass to the lower substrate on the lower substrate of the substrate assembly protruding from the pad region, so that the deformation of the lower substrate is minimized even if the distance between the cover glass and the lower substrate changes.

According to another aspect of the present invention, the thickness of the adhesive member changes to a thickness corresponding to the distance between the cover glass and the lower substrate when the distance between the cover glass and the lower substrate changes.

According to another aspect of the present invention, an adhesive member is formed of an additive which is mixed with an ultraviolet-curable composition and an ultraviolet-curable composition and reduces the elastic modulus of the adhesive member by heat or infrared rays, and increases the elongation of the adhesive member.

According to still another aspect of the present invention, there is provided an ultraviolet curable composition comprising a monofunctional acrylate monomer, a polyfunctional epoxy acrylate oligomer having at least two functional groups, a photoinitiator, and a silane compound And the additive is an ethoxyacrylate compound represented by the following general formula (1).

[Chemical Formula 1]

(Provided that R1 and R2 are each independently a hydrogen atom or a C1 to C5 alkyl group, and n is an integer of 5 to 40)

According to another feature of the present invention, the additive is included in an amount of 10 wt% to 30 wt% based on the total weight of the ultraviolet curable composition and the additive.

According to another aspect of the present invention, the adhesive member has a first modulus of elasticity and a first elongation at curing of the ultraviolet-curable composition, wherein the additive reacts with heat or infrared rays to change the modulus of elasticity of the adhesive member to less than the first modulus 2 elastic modulus, and the elongation percentage of the adhesive member is increased to a second elongation rate larger than the first elongation rate.

According to another aspect of the present invention, the first elastic modulus is greater than or equal to 480 N / mm ² at room temperature (25 ° C), the second elastic modulus is from 100 N / mm ² to 170 N / mm ² at room temperature , The first elongation is less than or equal to 90%, and the second elongation is greater than or equal to 300%.

According to another aspect of the present invention, the pad region of the lower substrate includes a driving chip region in which the driving chip is disposed and a touch pad region in which the touch pads are disposed on both sides of the driving chip region, Respectively.

According to another aspect of the present invention, the liquid crystal display further includes an optical bonding member disposed between the cover glass and the upper substrate, and a dam member surrounding the optical bonding member.

According to an aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device including forming a dam member on an upper substrate of a substrate assembly including a lower substrate and an upper substrate facing each other, Applying a composition for an optical adhesive member on a substrate, applying a composition for an adhesive member onto a lower substrate projecting from a pad surface at one side of the upper substrate, forming a composition for an adhesive member on a lower surface of the cover glass facing the substrate assembly Pressing the cover glass using an electrostatic chuck so as to be in contact with the cover member; curing the composition for the adhesive member so that the adhesive member is formed; Separating the glass from the glass and raising the process pressure, Curing the composition for the optical bonding member such that the cover glass and the upper substrate of the substrate assembly are adhered to each other, reducing the elastic modulus of the adhesive member, and heating the adhesive member to increase the elongation of the adhesive member Or irradiating the adhesive member with infrared light.

According to another aspect of the present invention, the step of pressurizing the cover glass using the electrostatic chuck such that the composition for the adhesive member is brought into contact with the bottom surface of the cover glass opposite to the substrate assembly is performed by moving the distance between the cover glass and the lower substrate to the first distance Wherein the step of curing the composition for the adhesive member to form the adhesive member comprises curing the composition for the adhesive member such that the adhesive member has a first thickness corresponding to the first distance.

According to still another aspect of the present invention, the step of separating the electrostatic chuck from the cover glass and raising the process pressure so that the composition for the optical bonding member covers the entire surface of the upper substrate inside the dam member is performed between the cover glass and the lower substrate Of the adhesive member to a second distance larger than the first distance by applying heat to the adhesive member to reduce the elastic modulus of the adhesive member and to increase the elongation of the adhesive member, The step of increasing the thickness of the adhesive member from a first thickness to a second thickness corresponding to a second distance.

According to another aspect of the present invention, there is provided a method of manufacturing an optical element, comprising the steps of: curing a composition for an optical bonding member such that a cover glass and an upper substrate of a substrate assembly are adhered to each other; The step of applying heat or irradiating infrared rays to the adhesive member is performed simultaneously.

The details of other embodiments are included in the detailed description and drawings.

The present invention minimizes the light leakage caused by the deformation of the lower substrate by using the adhesive member which minimizes the deformation of the lower substrate even if the distance between the cover glass and the lower substrate is changed by bonding the cover glass and the lower substrate have.

INDUSTRIAL APPLICABILITY The present invention can improve the productivity of a liquid crystal display device by using an adhesive member having a large elastic modulus and a small elongation ratio by a first reaction and having a small elastic modulus and a large elongation by a secondary reaction, There is an effect of improving the durability.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

FIG. 1A is a schematic perspective view illustrating a light leakage phenomenon and a durability reduction phenomenon occurring in a liquid crystal display device. FIG.
1B is a schematic cross-sectional view taken along line I-I 'of FIG. 1A for explaining a light leakage phenomenon and a durability reduction phenomenon generated in a liquid crystal display device.
2A is a schematic plan view illustrating a liquid crystal display according to an embodiment of the present invention.
FIG. 2B is a schematic cross-sectional view taken along line II-II 'of FIG. 2A for explaining a liquid crystal display device according to an embodiment of the present invention.
3 is a graph for explaining change in elastic modulus of a bonding member included in a liquid crystal display device according to an embodiment of the present invention.
4A to 4F are schematic cross-sectional views illustrating a process of minimizing deformation of a lower substrate included in a liquid crystal display device according to an exemplary embodiment of the present invention.
5A to 5C are schematic plan views and graphs for explaining reduced light leakage phenomenon of a liquid crystal display device according to an embodiment of the present invention.
6 is a schematic flowchart for explaining a method of manufacturing a liquid crystal display device according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Where the terms "comprises", "having", "done", and the like are used in this specification, other portions may be added unless "only" is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

It is to be understood that an element or layer is referred to as being another element or layer " on ", including both intervening layers or other elements directly on or in between.

Although the first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

Like reference numerals refer to like elements throughout the specification.

The sizes and thicknesses of the individual components shown in the figures are shown for convenience of explanation and the present invention is not necessarily limited to the size and thickness of the components shown.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

Various embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

2A is a schematic plan view illustrating a liquid crystal display according to an embodiment of the present invention. FIG. 2B is a schematic cross-sectional view taken along line II-II 'of FIG. 2A for explaining a liquid crystal display device according to an embodiment of the present invention. 2A and 2B, a liquid crystal display 200 includes a substrate assembly 210, an adhesive member 260, an optical adhesive member 221, a dam member 222, and a cover glass 230. 2A, the upper substrate 212 and the cover glass 230 of the substrate assembly 210 are omitted, and the display elements disposed in the non-pad region NPA are omitted.

The substrate assembly 210 includes a lower substrate 211, an upper substrate 212, a sealant 213, a liquid crystal LC, a driving chip DI, a touch pad unit TP, a display printed circuit board 240, And a printed circuit board (250).

The lower substrate 211 is a substrate for supporting various components of the liquid crystal display 200, and may be a glass substrate or a plastic substrate. The lower substrate 211 has an area larger than that of the upper substrate 230 and one boundary surface of the lower substrate 211 protrudes from one surface of the upper substrate 212 corresponding thereto. As a result, a portion of the upper surface of the lower substrate 211 is exposed. A region where the lower substrate 211 is exposed is defined as a pad region PA and a region where the lower substrate 211 and the upper substrate 212 are overlapped is defined as a non-pad region NPA.

The driver chip DI, the touch pad TP and the adhesive member 260 are disposed in the pad region PA and the display device 210 constituting the pixel of the liquid crystal display device 200 is disposed in the non- (display element) and wirings for transmitting various signals to the display element are arranged. The non-pad area NPA is divided into an active area where a display element is arranged and an image is displayed, and a bezel area where wirings connected to the display element are arranged and an image is not displayed. The display device may include a thin film transistor (TFT), a pixel electrode connected to the thin film transistor, and a common electrode separated from the pixel electrode. The wirings transfer the voltage to drive the display element, and may be constituted by, for example, a gate wiring for transferring a gate voltage, a data wiring for transferring a data voltage, and a touch wiring for transferring a touch signal.

The driving chip DI is connected to the display printed circuit board 240 and receives a signal from the display printed circuit board 240 to provide a driving voltage to the display device. For convenience of explanation, the driving chip DI is not specifically shown in FIG. 2A, and the driving chip region in which the driving chip DI is disposed is indicated by a dotted line. The driving chip DI may include at least one of a data driving circuit for providing a data voltage to the display element and a gate driving circuit for providing a gate voltage to the display element. The driving chip DI may be mounted on the lower substrate 211 by a COG (Chip On Glass) method.

The touch pad unit TP is connected to the touch printed circuit board 250 and receives a touch signal from the touch wiring and transmits the touch signal to the touch printed circuit board 250. The touch pad unit TP is disposed on both sides of the pad area PA so as not to overlap with the driving chip DI and the touch printed circuit board 250 is connected to the touch wirings through the touch pad unit TP . In FIG. 2A, the touch pad unit TP is not specifically shown, and the area of the touch pad unit where the touch pad unit TP is disposed is indicated by a dotted line.

The adhesive member 260 is disposed on both sides of the pad region PA so as to partially overlap the touch pad portion TP. However, the present invention is not limited thereto, and the adhesive member 260 may be disposed on both sides of the pad area PA so as not to overlap with the touch pad part TP. Although the rectangular adhesive member 260 is illustrated in FIG. 2A, the shape of the adhesive member 260 is not limited thereto, and the adhesive member 260 may be formed in a polygonal shape, a circular shape, or an elliptical shape except for a square shape. When the adhesive member 260 has a rectangular shape, the size of the adhesive member 260 is determined by the lateral width x and the longitudinal width y. For example, the lateral width x of the adhesive member 260 may be between 5 mm and 7 mm, and the longitudinal width y may be between 2 mm and 3 mm. However, the present invention is not limited thereto, and the width of the adhesive member 260 can be freely selected. For example, the larger the vertical width y of the adhesive member 260, the wider the total area of the pad area PA can be, and therefore the longitudinal width y of the adhesive member 260 is larger than the entire width of the pad area PA It can be appropriately selected so as not to widen the area. The adhesive member 260 may adhere the lower substrate 211 and the cover glass 230 in the pad area PA so that the lower substrate 211 and the cover glass 230 are bonded to each other even if the distance between the cover glass 230 and the lower substrate 211 is changed. Thereby minimizing the deformation. A detailed description of the adhesive member 260 will be described later.

Referring to FIG. 2B, in the non-pad region NPA, the upper substrate 212 overlaps the lower substrate 211. The upper substrate 212 may be made of glass or transparent plastic having excellent light transmittance so that the image implemented through the display element can be displayed well.

The sealant 213 bonds the upper substrate 212 and the lower substrate 211 and the liquid crystal LC is filled in the inner space formed by the upper substrate 212, the lower substrate 211 and the sealant 213 . The sealant 213 seals between the upper substrate 212 and the lower substrate 211 to protect the display element and the wires from the external environment.

The cover glass 230 covers the substrate assembly 210 and is made of glass having excellent rigidity or thermoformable and workable plastic such as to protect the components of the substrate assembly 210 from external shocks, &Lt; / RTI >

The optical bonding member 221 bonds the cover glass 230 and the substrate assembly 210 between the upper substrate 212 and the cover glass 230 of the substrate assembly 210. The optical adhesive member 221 may be formed of a composition for an optical adhesive member of an acrylate series which is cured by light or heat. The composition for the optical adhesive member may comprise, for example, an acrylate-based monomer, an acrylate-based oligomer and an initiator that is photo-responsive or heat-responsive.

The dam member 222 performs a dam function to prevent the composition for the optical bonding member from overflowing when the composition for the optical bonding member is applied on the upper substrate 212, . The dam member 222 is formed before the composition for the optical bonding member is applied, and may be formed so as to surround the rim of the upper substrate 212.

The adhesive member 260 adheres the lower substrate 211 and the cover glass 230 and buffers the impact applied to the lower substrate 211 in the pad region PA. Thus, the adhesive member 260 may also be referred to as a buffer member. As described above, in the non-pad region NPA, the lower substrate 211 overlaps the upper substrate 212, and in the non-pad region NPA, the substrate assembly 210 has a double substrate structure. On the other hand, in the pad region PA, the lower substrate 211 is exposed alone. 2A, in the pad area PA, the display printed circuit board 240 and the touch printed circuit board 250 are electrically connected to the driving chip DI and the touch pad part TP on the lower substrate 211, The lower substrate 211 is in contact with the lower substrate 211. The upper surface of the lower substrate 211 is exposed in the pad area PA and one surface of the lower substrate 211 protrudes from one surface of the upper substrate 230 corresponding thereto.

As shown in FIG. 2B, the lower substrate 211 exposed in the pad area PA is thinner than the cover glass 230, so is vulnerable to an external impact, and is easier to cover than the cover glass 230 It can be curved. The adhesive member 260 has a thickness corresponding to the distance between the cover glass 230 and the lower substrate 211 so as to minimize the bending of the lower substrate 211 and keep the lower substrate 211 in a plat . That is, the thickness of the adhesive member 260 may vary corresponding to the distance between the cover glass 230 and the lower substrate 211 when the distance between the cover glass 230 and the lower substrate 211 changes. That is, the adhesive member 260 is a soft member having an elongation capable of adapting to a change in distance between the cover glass 230 and the lower substrate 211.

Further, the adhesive member 260 has a modulus of elasticity suitable for absorbing the impact applied to the lower substrate 211. That is, it is a flexible member that can restore the deformed lower substrate 211 to its original state even if the lower substrate 211 is deformed by an impact.

The adhesive member 260 is formed of a composition for an adhesive member. The characteristics of the above-described adhesive member 260 are determined by a first-order reaction in which a composition for an adhesive member is cured by irradiating ultraviolet (UV) to the composition for an adhesive member, heat is applied to the composition for the adhesive member, Infrared (IR) is irradiated to soften the composition for the cured adhesive member. The adhesive member 260 is formed of an ultraviolet curable composition and an additive. The ultraviolet ray curable composition is cured by the first reaction, and the additives reduce the elastic modulus of the adhesive member 260 by the secondary reaction and increase the elongation of the adhesive member 260.

The UV curable composition comprises a monofunctional acrylate monomer, a multifunctional acrylate oligomer having at least two functional groups, a photoinitiator and a silane based compound.

Monofunctional acrylate monomers include monomers containing one acrylate functional group such as 2-hydroxyethyl acrylate (2-HEA), 2-carboxyethyl acrylate (2- carboxyethyl acrylate (2-CEA), tertiary butyl cyclohexanol acrylate, C16 / C18 alkyl acrylate, C12 alkyl acrylate (Lauryl acrylate), C12 / C14 acrylate, 2-phenoxyethyl acrylate (2-PEA), ethoxylated 4 phenyl acrylate (P4EOA), isooctyl acrylate Octyl acrylate (IOA), octyl decyl acrylate (ODA), etc. However, the monofunctional acrylate monomer is not limited thereto, and one acrylate functional group There are a variety of acrylate monomers containing may be used. Monofunctional acrylate-based monomer may be included as a 5 wt% to 30 wt%, based on the total weight of the composition of the binding material.

The polyfunctional acrylate oligomer is an acrylate oligomer having at least two acrylate functional groups. For example, an epoxy acrylate oligomer containing two to six acrylate functional groups may be used. However, the polyfunctional acrylate oligomer is not limited thereto, and various acrylate oligomers including at least two acrylate functional groups may be used. The polyfunctional acrylate oligomer is polymerized with a monofunctional acrylate monomer to form an acrylate polymer having a network structure, through which an adhesive member 260 is formed. The polyfunctional acrylate oligomer may be included in an amount of 1 wt% to 5 wt% based on the total weight of the composition for the adhesive member.

The photoinitiator initiates polymerization of monofunctional acrylate monomer and polyfunctional acrylate oligomer in response to ultraviolet radiation. Photoinitiators include, for example, azo compounds, quinones, nitroso compounds, acyl halides, hydrazones, mercapto compounds, pyrylium compounds, Compounds such as imidazole, cyanuric chloride, benzoin, benzoin arcyl ether, diketone, phenon, benzoin ether, And mixtures thereof. The photoinitiator may be included in an amount of 1 wt% to 10 wt% based on the total weight of the composition for the adhesive member.

The silane-based compound increases the surface adhesion of the adhesive member 260. That is, the surface adhesive force at the interface between the adhesive member 260 and the cover glass 230 and the surface adhesive force at the interface between the adhesive member 260 and the lower substrate 211 are increased. The silane-based compound may be, for example, silanol (SiH ₂ (OH) ₂ ; silanol), and may be contained in an amount of 0.5 wt% to 3 wt% based on the total weight of the composition for the adhesive member.

The additive is a compound that decreases the elastic modulus of the adhesive member 260 in response to heat or infrared rays and increases the elongation of the adhesive member 260. The additive is an ethoxy acrylate / RTI >

[Chemical Formula 1]

R ₁ and R ₂ are each independently a hydrogen (H) atom or a C ₁ to C ₅ alkyl group, and n is an integer of 5 to 40. The ethoxy acrylate-based compound reacts with heat or infrared rays to soften the adhesive member 260, thereby reducing the elastic modulus of the adhesive member 260 and increasing the elongation of the adhesive member 260.

(Meth) acrylate (MPEGMA), polyethoxy (5) (meth) acrylate (meth) acrylate (meth) acrylate polyethoxy (5) (meth) acrylate, polyethoxy (10) (meth) acrylate, polyethoxy (30) (meth) (meth) acrylate, behenylpolyethoxy (25) (meth) acrylate, lauryl polyethoxy (23) (meth) acrylate (Laurypolyethoxy (meth) acrylate, methoxypolyethoxy (meth) acrylate, methoxypolyethoxy (meth) acrylate, methoxypolyethoxy (meth) acrylate, (meth) acrylate, methoxypolyethoxy (16) (meth) acrylate and the like can be used. However, the type of the ethoxyacrylate compound is not limited thereto, and various ethoxyacrylate compounds satisfying the above formula (1) can be used. The additive may be included in an amount of 10 wt% to 30 wt% based on the total weight of the composition for the adhesive member.

As mentioned above, the adhesive member 260 is formed of a composition for an adhesive member, and the composition for an adhesive member includes an ultraviolet curable composition and an additive. In this case, the ultraviolet ray curable composition is cured by the first reaction to have a large modulus of elasticity and a small elongation, and the additive decreases the modulus of elasticity of the adhesive member 260 by the secondary reaction and increases elongation. Therefore, the elastic modulus and elongation of the adhesive member 260 can be changed according to the first reaction and the second reaction. For a more detailed description of this, reference is made to Fig.

3 is a graph for explaining change in elastic modulus of a bonding member included in a liquid crystal display device according to an embodiment of the present invention. 3, the elastic modulus of the adhesive member increases to a first elastic modulus (M ₁ ) based on the first reaction of the composition for the adhesive member, and the elastic modulus of the first elastic modulus (M ₁ ) to the second elastic modulus (M ₂ ).

For example, when the composition for the adhesive member is irradiated with ultraviolet rays for T ₁ hour, the ultraviolet curable composition contained in the composition for the adhesive member is cured to have the first elastic modulus (M ₁ ). Therefore, the adhesive member has a first modulus of elasticity in the first reaction. Here, the elastic modulus means a modulus of elasticity at room temperature (25 ° C), and the first modulus is 480 N / mm ² . The upper limit value of the first elastic modulus is not particularly limited. That is, the adhesive member may have an arbitrary elastic modulus greater than 480 N / mm < ^{2 &} gt ;, and the higher the elastic modulus of the adhesive member is, the better the rigidity of the adhesive member is, and the adhesive member is aligned with the cover glass- Can be prevented. A detailed description thereof will be given later with reference to Figs. 4A to 4F.

Thereafter, the composition for the adhesive member may be heated or irradiated with infrared rays for T ₂ hours at T ₁ . In this case, the additive contained in the composition for the adhesive member reduces the elastic modulus of the cured UV-curable composition from the first elastic modulus (M ₁ ) to the second elastic modulus (M ₂ ). Accordingly, the adhesive member has a second elastic modulus (M ₂ ) smaller than the first elastic modulus (M ₁ ) in the second-order reaction. Here, the second elastic modulus (M ₂ ) has a value selected from 100 N / mm ² to 170 N / mm ² .

The adhesive member having the second elastic modulus M ₂ is suitable for buffering the impact applied to the lower substrate and is capable of continuously adhering between the cover glass and the lower substrate even if the distance between the cover glass and the lower substrate is changed, And may be suitable for minimizing deformation of the lower substrate. If the elastic modulus of the adhesive member is less than 100 N / mm < ² >, the adhesive member has too small an elastic force, so that the lower substrate may not be restored when the lower substrate is excessively deformed, It may not be suitable for shock damping. Further, when the elastic modulus of the adhesive member is larger than 170 N / mm < ^{2 &} gt ;, the adhesive member has a too large elastic force. Thus, the bonding member may not be able to adapt to a change in distance between the lower substrate and the cover glass, which may occur in the process of bonding the cover glass and the substrate assembly, and may not minimize deformation of the lower substrate. A detailed description thereof will be given later with reference to Figs. 4A to 4F.

On the other hand, as the modulus of elasticity of the adhesive member is changed based on the primary reaction and the secondary reaction, the elongation percentage of the adhesive member can also be changed. Elongation means the ratio of elongation length of an object when the tensile force is applied to a specific object, and elongation can be increased when the elastic modulus is decreased. As mentioned above, the ultraviolet ray curable composition contained in the composition for the adhesive member is hardened in response to ultraviolet rays. Thus, the elongation percentage of the adhesive member can be reduced during a period of T ₁ during which ultraviolet light is irradiated. However, the additives included in the composition for the adhesive member relax the rigidity of the cured UV-curable composition in response to heat or infrared rays. Thus, the elongation percentage of the adhesive member can be increased for T ₂ hours at T ₁ where heat is applied to the adhesive member or infrared light is irradiated.

For example, the elongation of the adhesive member can be increased at a first elongation rate for a T ₁ hour. Here, the first elongation may be less than or equal to 90%. For example, the first elongation may have any value selected from 0% to 90%. When the elongation is 0%, it means that there is no change in the size of the adhesive member when a tensile force is applied to the adhesive member. When the adhesive member has an elongation of less than or equal to 90%, the adhesive member can maintain a constant distance between the cover glass and the lower substrate, and the cover glass and the lower substrate may not be mutually staggered.

Further, the elongation of the adhesive member can be increased at the second elongation rate for T ₂ hours at T ₁ . For example, the second elongation may be greater than or equal to 300%. If the elongation percentage of the adhesive member is less than 300%, the adhesive member may not adapt to the change in distance between the cover glass and the lower substrate, which may occur in the process of bonding the cover glass and the substrate assembly, When the distance between the upper substrate and the lower substrate is changed, it may fall from the cover glass or the lower substrate. On the other hand, the upper limit value of the second elongation is not particularly limited. That is, since the adhesive member after the secondary reaction must adhere firmly to the cover glass and the lower substrate even if the distance between the cover glass and the lower substrate changes, the higher the elongation of the adhesive member, the better. A detailed description thereof will be given later with reference to Figs. 4A to 4F.

As a result, the elastic modulus of the adhesive member is increased by the first-order reaction and the elongation is reduced. Thus, the adhesive member can be a rigid member. However, the elastic modulus of the adhesive member is decreased by the secondary reaction and the elongation is increased. Therefore, the adhesive member can be a flexible member. Due to the above-described characteristics of the adhesive member, the deformation of the lower substrate, which may occur in the process of the liquid crystal display, can be minimized, and the light leakage phenomenon that can be caused by deformation of the lower substrate can be minimized. In addition, after the liquid crystal display device is manufactured, the adhesive member can prevent damage to the lower substrate by buffering impact applied to the lower substrate.

4A to 4F are schematic cross-sectional views illustrating a process of minimizing deformation of a lower substrate included in a liquid crystal display device according to an exemplary embodiment of the present invention. 4A to 4F, the light leakage phenomenon of the liquid crystal display device may be caused by the deformation of the lower substrate 211 of the liquid crystal display device and the deformation of the lower substrate 211 may be caused by the cover glass 230 and the substrate assembly 210 May adhere to each other. 4A to FIG. 4F are diagrams showing steps of bonding the cover glass 230 and the substrate assembly 210 in steps. Referring to FIGS. 4A to 4F, a description will be given of how the adhesive member 260 improves light leakage .

Referring first to FIG. 4A, a dam member 222 is formed on an upper substrate 212 of a substrate assembly 210. As mentioned above, the dam member 222 prevents the composition 423 for the optical bonding member from overflowing when the composition 423 for the optical bonding member is applied on the upper substrate 212. Therefore, the dam member 222 can be formed before the composition 423 for the optical bonding member is applied. The dam member 222 may be formed to surround the rim of the upper substrate 212 and may be formed to have a thickness suitable for preventing overflow of the composition 423 for the optical bonding member.

Thereafter, the composition 423 for the optical bonding member is applied onto the upper substrate 212 inside the dam member 222. The composition 423 for the optical adhesive member may be applied to cover the entire surface of the upper substrate 212, but may be applied to cover only a part of the upper surface of the upper substrate 212, as shown in FIG. 4A. Since the composition 423 for a coated optical adhesive member is not yet cured, the adhesive force is small and has a very small elastic modulus.

A composition 461 for an adhesive member is applied on the pad area PA of the lower substrate 211 which protrudes from one surface of the upper substrate 212. The composition (461) for a bonding member includes an ultraviolet ray curable composition and an additive. The adhesive composition 461 may be applied to both sides of the pad area PA so as to partially overlap the touch pad part. Since the applied composition 461 for the adhesive member is not cured, the adhesive force is small and has a very small elastic modulus.

Referring to FIG. 4B, a cover glass 230 is aligned over the substrate assembly 210 to face the substrate assembly 210. The cover glass 230 can be fixedly carried on an electrostatic chuck (ESC). The electrostatic chuck ESC may align the cover glass 230 with the substrate assembly 210 such that one surface of the cover glass 230 corresponds to one surface of the lower substrate 211.

Referring to FIG. 4C, the cover glass 230 is pressed using an electrostatic chuck (ESC) so that the composition for the adhesive member is brought into contact with the lower surface of the cover glass 230. In this case, in order to maximize the contact area between the cover glass 230 and the composition for the adhesive member, the cover glass 230 is excessively pressed, and the distance between the lower surface of the cover glass 230 and the upper surface of the lower substrate 211 is 1 < / RTI &_gt; distance d1. On the other hand, since the cover glass 230 is excessively pressed, the dam member 222 can be compressed by the cover glass 230, and the thickness of the dam member 222 can be reduced.

Ultraviolet rays (UV) are applied to the composition for the adhesive member in a state in which the cover glass 230 is pressed. In this case, the ultraviolet-curable composition contained in the composition for the adhesive member is cured, and the adhesive member 260 is formed based on the first reaction. As described above, when the ultraviolet ray-curable composition is irradiated with ultraviolet light (UV), the monofunctional acrylate-based monomer and the polyfunctional epoxy acrylate-based oligomer are polymerized to form an acrylate polymer, And the lower substrate 211 are bonded to each other. The primary reaction can be carried out, for example, using ultraviolet light having a wavelength of 365 nm.

The elastic modulus of the adhesive member 260 is increased to the first elastic modulus by the first reaction and the elongation of the adhesive member 260 is reduced to the first elongation. The adhesive member 260 has a large first modulus of elasticity to maintain the alignment of the cover glass 230 and the substrate assembly 210. For example, the first modulus of elasticity may be greater than or equal to 480 N / mm ² . In addition, the adhesive member 260 has a small first elongation to firmly bond the cover glass 230 and the lower substrate 211. For example, the first elongation may be less than or equal to 90%. In this case, the adhesive member 260 can minimize the alignment of the cover glass 230 and the substrate assembly 210, and even if the alignment of the cover glass 230 and the substrate assembly 210 is broken, 230 and the substrate assembly 210 to the initial alignment.

4D, the electrostatic chuck is separated from the cover glass 230, and the process pressure is raised. In this case, due to a sudden pressure change, the composition 423 for the optical bonding member can spread so as to cover the entire surface of the upper substrate 212 inside the dam member 222. Specifically, the composition 423 for the optical adhesive member may not be applied to cover the entire surface of the upper substrate 212 due to an error in the coating process. Since the optical bonding member is a member that continuously adheres the cover glass 230 and the substrate assembly 210 after the liquid crystal display is completed, the bonding area of the optical bonding member needs to be maximized. Therefore, it is necessary to spread the composition 423 for the optical adhesive member so as to cover the entire surface of the upper substrate 212 before the composition 423 for the optical adhesive member is cured. If the process pressure suddenly rises as the electrostatic chuck separates from the cover glass 230, the composition 423 for the optical adhesive member spreads on the upper substrate 212 due to a momentary pressure change. For example, the process of aligning the cover glass 230 on the substrate assembly 210 and curing the composition for the adhesive member can all be performed in a vacuum state. However, after the composition for the adhesive member is cured, the process pressure may suddenly rise to normal pressure as the electrostatic chuck separates from the cover glass 230. In this case, the composition 423 for the optical adhesive member is spread with a sudden pressure change, and the composition 423 for the optical adhesive member fills the inside of the dam member 222. Thus, the composition 423 for the optical adhesive member covers the entire surface of the upper substrate 212.

In this case, the adhesive member 260 maintains the alignment of the cover glass 230 and the substrate assembly 210. That is, alignment between the cover glass 230 and the substrate assembly 210 can be maintained by the electrostatic chuck which pressurizes the cover glass 230 before the composition for the adhesive member is cured. However, since the alignment of the cover glass 230 and the substrate assembly 210 can not be maintained by the electrostatic chuck after the electrostatic chuck is separated from the cover glass 230, the cover glass 230 and the substrate assembly 210 A member that maintains the alignment is needed. In particular, the electrostatic chuck must be separated from the cover glass 230 before the composition for the adhesive member is cured, and the composition 423 for the optical adhesive member can not be cured with the cover glass 230 pressed by the electrostatic chuck . The composition for optical adhesive member 423 is difficult to completely cover the entire surface of the upper substrate 212 and the composition for optical adhesive member 423 is applied to the front surface of the upper substrate 212 as shown in FIG. Air bubbles may be generated between the cover glass 230 and the composition 423 for an optical bonding member even if it is coated. The cover glass 230 and the substrate assembly 210 may not be firmly adhered to each other when the composition 423 for an optical adhesive member is cured while bubbles are present. Further, when bubbles are present in the active region, the visibility of the liquid crystal display device may be lowered due to bubbles. Therefore, a process of removing air bubbles between the composition 423 for the optical bonding member and the cover glass 230 must be performed before the composition 423 for the optical bonding member is cured. Since the electrostatic chuck covers the upper surface of the cover glass 230 when pressing the cover glass 230 continuously with the electrostatic chuck, the accurate position of the air bubbles generated between the cover glass 230 and the optical adhesive member 221 And it may be difficult to remove air bubbles between the cover glass 230 and the upper substrate 212. [ Therefore, in order to efficiently remove bubbles, the electrostatic chuck must be separated from the cover glass 230.

As a result, in order to remove air bubbles between the cover glass 230 and the composition 423 for the optical adhesive member, the electrostatic chuck must be separated from the cover glass 230, and after the electrostatic chuck is separated from the cover glass 230, A member capable of maintaining the alignment of the glass 230 and the substrate assembly 210 is required. The adhesive member 260 adheres the cover glass 230 and the lower substrate 211 of the substrate assembly 210 to each other so as to maintain the alignment of the cover glass 230 and the substrate assembly 210 after the electrostatic chuck is separated .

In this case, the adhesive member 260 has a small first elongation so as to maintain the alignment of the cover glass 230 and the substrate assembly 210. That is, as mentioned above, since the adhesive member 260 has an elongation of less than or equal to 90%, the adhesive member 260 can minimize the distance change between the cover glass 230 and the substrate assembly 210 And it is possible to minimize the misalignment between the cover glass 230 and the substrate assembly 210. If the elongation percentage of the adhesive member 260 is greater than 90%, the size of the adhesive member 260 may excessively increase, and the alignment of the cover glass 230 and the substrate assembly 210 may be distorted.

Also, the adhesive member 260 has a large first elastic modulus so that the alignment of the cover glass 230 and the substrate assembly 210 may be reversed to the initial alignment. That is, as mentioned above, the adhesive member 260 has a modulus of elasticity of greater than or equal to 480 N / mm ² , and the adhesive member 260 is not in contact with the cover glass 230 and the substrate assembly 210 The cover glass 230 and the substrate assembly 210 can be returned to the initial alignment state due to the elastic force of the adhesive member 260. If the adhesive member 260 has a modulus of elasticity of less than 480 N / mm ² , the adhesive member 260 may be attached to the cover glass 230 when the alignment of the cover glass 230 and the substrate assembly 210 is broken. And the alignment of the substrate assembly 210 to the initial state.

On the other hand, since the electrostatic chuck is separated from the cover glass 230 and the pressure applied to the cover glass 230 is released, the thickness of the compressed dam member 222 can be restored to its original state. This in result, the cover glass 230 may be slightly raised, non-pad area when in (NPA), the cover glass 230 and the lower substrate 211, the distance the first distance (d ₁₎ between the upper surface of the second Can be increased to the distance d ₂ . The thickness of the adhesive member 260 does not change and the adhesive member 260 is bonded to the cover glass 230 and the lower substrate 211. The adhesive member 260 has a large first elastic modulus and a small first elongation, Thereby keeping the distance between them constant. The distance between the lower surface of the cover glass 230 and the upper surface of the lower substrate 211 in the pad area PA where the adhesive member 260 is disposed can be maintained at the first distance d ₁ . As a result, as shown in FIG. 4D, the lower substrate 211 in the pad region PA may be slightly deformed, and the lower substrate 211 may be bent.

The bending of the lower substrate 211 generated in the pad region PA can locally deform the LC arrangement of the non-pad region NPA. That is, the distance between the lower substrate 211 and the upper substrate 212 at the non-pad region NPA may be slightly changed due to the bending of the lower substrate 211, Can be. In particular, when the liquid crystal (LC) array of the active region is turned off, light leakage can be generated between the misaligned liquid crystals LC. Therefore, in order to minimize the light leakage, the deformation of the lower substrate 211 must be minimized before the liquid crystal display device is completed. As described above, since the deformation of the lower substrate 211 is caused by the large elastic modulus of the adhesive member 260 and the small elongation, it is necessary to reduce the modulus of elasticity of the adhesive member 260 and to increase the elongation have. That is, the rigidity of the adhesive member 260 needs to be reduced.

4E, a process of removing air bubbles between the composition for the optical bonding member and the cover glass 230 may be performed. The process of removing the bubbles can be performed in such a manner that the bubbled portion is partially pressed to completely adhere the cover glass 230 to the composition for the optical bonding member, for example. After all of the bubbles have been removed, the composition for the optical adhesive member can be cured. For example, the composition for the optical bonding member can be cured through light or heat. FIG. 4E shows a state in which heat is applied to the composition for the optical bonding member. By curing the composition for the optical adhesive member, the optical adhesive member 221 is formed.

After the optical adhesive member 221 is formed, the adhesive member 260 may be heated or irradiated with infrared rays. That is, a secondary reaction of the adhesive member 260 can be induced by heat or infrared rays. Meanwhile, as shown in FIG. 4E, the second reaction of the adhesive member 260 may be performed simultaneously in the process of forming the optical adhesive member 221. [ For example, when the composition for an optical bonding member is cured by heat, the liquid crystal display may be subjected to heat at 70 to 90 캜. In this case, heat is also applied to the adhesive member 260, so that the second reaction of the adhesive member 260 can be induced while the composition for the optical adhesive member is cured.

Referring to FIG. 4F, the elastic modulus of the adhesive member 260 is decreased by the secondary reaction, and the elongation of the adhesive member 260 is increased. That is, the ethoxyacrylate compound contained in the composition for the adhesive member can alleviate the rigidity of the acrylate polymer formed by the polymerization of the monofunctional acrylate-based monomer and the polyfunctional epoxy acrylate-based oligomer by the secondary reaction. Thus, the elastic modulus of the adhesive member 260 can be reduced, and the elongation can be increased.

The elastic modulus of the adhesive member 260 can be reduced from the first elastic modulus to the second elastic modulus and the elongation of the adhesive member 260 can be increased from the first elongation to the second elongation. For example, the second elastic modulus may have any value selected from the range of 100 N / mm ² to 170 N / mm ² , and the second elongation may have a value greater than or equal to 300%.

Alignment of the cover glass 230 and the substrate assembly 210 is maintained only by the adhesive member 260 before the optical adhesive member 221 is formed. In particular, alignment of the cover glass 230 and the substrate assembly 210 may be interrupted in the process of removing air bubbles that may occur between the composition for the optical adhesive member and the cover glass 230. Therefore, in order to maintain the alignment of the cover glass 230 and the substrate assembly 210, and to return the misaligned alignment to the initial state, the adhesive member 260 needs to have a large modulus of elasticity and a small elongation. However, since the cover glass 230 and the substrate assembly 210 are bonded by the optical bonding member 221 after the optical bonding member 221 is formed, the bonding member 260 needs to have a large elastic modulus No need to have a small elongation. Rather, deformation of the lower substrate 211 may be caused due to a large elastic modulus of the adhesive member 260 and a small elongation, and there is a risk that light leakage is generated. Therefore, after the optical bonding member 221 is formed, the modulus of elasticity of the bonding member 260 needs to be reduced, and the elongation of the bonding member 260 needs to be increased.

As shown in Fig. 4F, the elastic modulus of the adhesive member 260 is reduced to a second elastic modulus due to the secondary reaction, and the elongation of the adhesive member 260 is increased to the second elongation. That is, due to the secondary reaction, the rigidity of the adhesive member 260 is relaxed, and the adhesive member 260 becomes a flexible member. In this case, the thickness of the adhesive member 260 can be increased corresponding to the second distance d ₂ between the cover glass 230 and the lower substrate 211, and the pad area PA and the non-pad area NPA The distance between the lower substrate 211 and the cover glass 230 can be kept constant. That is, the curved lower substrate 211 can be restored flat again, and the distance between the lower substrate 211 and the upper substrate 212 in the non-pad region NPA as the lower substrate 211 is restored flat It can be kept constant. Accordingly, the arrangement of the liquid crystal LC can be kept constant, and the light leakage phenomenon can be minimized.

On the other hand, even if the thickness of the adhesive member 260 changes, the adhesive member 260 can continuously adhere the cover glass 230 and the lower substrate 211. That is, since the elongation of the adhesive member 260 is equal to or greater than 300% due to the secondary reaction, the adhesive member 260 can be formed to have a thickness corresponding to the distance between the cover glass 230 and the lower substrate 211 Can easily be changed. If the elongation percentage of the adhesive member 260 is less than 300%, the adhesive member 260 can not adapt to the distance change between the cover glass 230 and the lower substrate 211, and the cover glass 230 or the lower substrate 211 ). &Lt; / RTI > However, if the elongation percentage of the adhesive member 260 is greater than or equal to 300%, the adhesive member 260 continues to contact the cover glass 230 and the lower substrate 211 despite the distance change between the cover glass 230 and the lower substrate 211. [ The substrate 211 can be bonded.

Further, the adhesive member 260 can buffer the impact applied to the lower substrate 211 after the liquid crystal display device is completed. That is, the elastic modulus of the adhesive member 260 is reduced from 100 N / mm ² to 170 N / mm ² by the secondary reaction, so that the impact applied to the lower substrate 211 can be mitigated. If the adhesive member 260 has an elastic modulus smaller than 100 N / mm ² , since the adhesive member 260 has an excessively small elastic force, the lower substrate 211 can be easily deformed by an external impact, The adhesive member 260 can not sufficiently absorb the external impact. If the adhesive member 260 has an elastic modulus greater than 170 N / mm ² , the adhesive member 260 can not sufficiently adapt to the distance change between the cover glass 230 and the lower substrate 211, 230 and the substrate assembly 210 may not be minimized.

That is, since the adhesive member 260 has a small modulus of elasticity and a high elongation after the liquid crystal display device is manufactured, the adhesive force of the adhesive force of the lower substrate 220, which may be generated in the process of bonding the cover glass 230 and the substrate assembly 210, The bending of the lower substrate 211 can be minimized and the impact applied to the lower substrate 211 after the liquid crystal display is manufactured can be sufficiently buffered. A method of minimizing the deformation of the lower substrate 211 and using the adhesive member 260 having a continuous ductility after the first reaction to buffer the impact applied to the lower substrate 211 may be considered. However, if the elastic modulus of the adhesive member 260 is kept small and the elongation is kept large, the alignment between the cover glass 230 and the substrate assembly 210 may be distorted before the optical adhesive member 221 is formed have. That is, since the composition for the optical bonding member is not cured in the process of separating the electrostatic chuck, the cover glass 230 and the substrate assembly 210 are bonded only by the adhesive member 260. The adhesive member 260 may be easily extended and the adhesive member 260 may be attached to the cover glass 230 and the substrate assembly 210. In this case, if the adhesive member 260 has a large elongation, May not be minimized. If the adhesive member 260 continuously has a small modulus of elasticity after the first reaction, the adhesive member 260 may be detached from the cover glass 230 and the cover glass 230 even if the alignment of the cover glass 230 and the substrate assembly 210 is distorted. The alignment of the substrate assembly 210 may not be returned to the initial state. Therefore, the adhesive member 260 becomes a rigid member in the process of bonding the cover glass 230 and the substrate assembly 210. After the cover glass 230 and the substrate assembly 210 are bonded to each other, .

As a result, the liquid crystal display according to an embodiment of the present invention includes the adhesive member 260 that becomes a rigid member by a first-order reaction and becomes a flexible member by a second-order reaction, Alignment errors of the cover glass 230 that may occur during the bonding process of the assembly 210 and deformation of the lower substrate 211 can be minimized. That is, the adhesive member 260 has a modulus of elasticity increased by the first reaction before the optical adhesive member 221 is formed, and has a reduced elongation. Thus, the alignment between the cover glass 230 and the substrate assembly 210 can be maintained by the adhesive member 260. Further, the adhesive member 260 has an elastic modulus reduced by the secondary reaction after the optical adhesive member 221 is formed, and has an increased elongation. Thus, even if the distance between the cover glass 230 and the lower substrate 211 changes, the deformation of the lower substrate 211 can be minimized. Therefore, the light leakage phenomenon caused by the deformation of the lower substrate 211 can be improved. In addition, after the manufacturing process of the liquid crystal display device, the durability of the liquid crystal display device can be improved because the adhesive member 260 cushions an impact applied to the lower substrate 211.

5A to 5C are a plan view and a graph for explaining reduced light leakage phenomenon of the liquid crystal display device according to an embodiment of the present invention.

Referring to FIG. 5A, the active area AA of the liquid crystal display 200 may be divided into arbitrary sections to test whether the liquid crystal display 200 generates light leakage. As mentioned above, the light leakage can be caused by the deformation of the lower substrate of the pad region and can be recognized at the edge portion of the active region AA adjacent to the pad region. Thus, any of the sections can be divided along the rim of the active area AA.

FIG. 5B is a graph obtained by testing whether a light leakage occurs in a liquid crystal display according to a comparative example, and FIG. 5C is a graph obtained by testing whether light leakage occurs in the liquid crystal display according to an exemplary embodiment of the present invention. The liquid crystal display device according to the comparative example and the liquid crystal display device according to the embodiment of the present invention all include the same components except for the adhesive member. The adhesive member of the liquid crystal display device according to the comparative example and the adhesive member of the liquid crystal display device according to the embodiment of the present invention were all disposed at the top of the 21 section and the 1 section shown in Fig. 5A.

On the other hand, the bonding member of the liquid crystal display device according to the comparative example was manufactured using Henkel's 190024 ultraviolet ray curable composition. The elastic modulus of the adhesive member of the liquid crystal display device according to the comparative example was 490 N / mm ² at room temperature and the elongation was 85%. The adhesive member of the liquid crystal display device according to an embodiment of the present invention was manufactured using the composition for the adhesive member described with reference to Figs. 2A and 2B. The second elastic modulus of the adhesive member of the liquid crystal display device according to an embodiment of the present invention was 169 N / mm ² at room temperature, and the second elongation was 300%. The first elastic modulus and the first elongation of the adhesive member are merely necessary for maintaining the alignment of the cover glass and the substrate assembly in the process of bonding the cover glass and the substrate assembly. The first elastic modulus and the first elongation of the adhesive member were not measured since the contact member had the second elastic modulus and the second elongation after the assembly was bonded.

The horizontal axis (i.e., the x axis) of the graph in Figs. 5B and 5C represents the sections of the liquid crystal display 200 shown in Fig. 5A, and the vertical axis (i.e., y axis) of the graph represents the pLcr value. The pLcr value is the ratio of the largest contrast ratio to the smallest contrast ratio of 100 divided parts when each section is divided into 100 parts. If the light leakage occurs in a specific section, the contrast ratio of the light leakage portion and the contrast ratio of the other portion have a large difference, so the pLcr value is increased. The graphs shown in FIGS. 5B and 5C were obtained by testing 32 liquid crystal display devices according to the comparative example manufactured in the same manner and 32 liquid crystal display devices according to an embodiment of the present invention, respectively. The boxes shown in Figs. 5B and 5C show the standard deviation of the pLcr values obtained from 32 liquid crystal display devices.

Referring to FIG. 5B, in the liquid crystal display according to the comparative example, the pLcr value was measured to be high in the 21 section and the 1 section. That is, it can be seen that light leakage can be generated in the upper left section and the upper right section of the liquid crystal display 200 shown in FIG. 5A. As described above, the adhesive member was disposed at the upper end of the 21 section and the 1 section of the liquid crystal display device according to the comparative example. Therefore, it can be seen that the adhesive member of the liquid crystal display device according to the comparative example causes light leakage.

Referring to FIG. 5C, in the liquid crystal display device according to an embodiment of the present invention, the pLcr value in the 21 section and the 1 section is measured to be small. That is, the light leakage of the liquid crystal display according to an embodiment of the present invention is significantly reduced because the bonding member minimizes the deformation of the lower substrate of the liquid crystal display.

On the other hand, although the graph is not shown, the inventor has conducted a drop evaluation to test the improved durability of the liquid crystal display according to an embodiment of the present invention. Specifically, the present inventors dropped 32 liquid crystal display devices according to the comparative example and 32 liquid crystal display devices according to an embodiment of the present invention at a height of 1 m, where the damage of 5.6% And the ratio of the generated liquid crystal display device was calculated.

As a result of the drop evaluation, damage occurred in the ratio of 4.6% in the liquid crystal display device according to the comparative example, but all 32 liquid crystal display devices were not damaged in the liquid crystal display device according to the embodiment of the present invention. Therefore, it can be seen that the adhesive member of the liquid crystal display device according to an embodiment of the present invention can fully buffer external impacts and minimize damage to the lower substrate.

6 is a schematic flowchart for explaining a method of manufacturing a liquid crystal display device according to an embodiment of the present invention. A method of manufacturing a liquid crystal display device according to an embodiment of the present invention has been described above with reference to FIGS. 4A to 4F, and a duplicate description thereof will be omitted.

Referring to FIG. 6, a method of manufacturing a liquid crystal display device according to an embodiment of the present invention includes forming a dam member on an upper substrate of a substrate assembly including a lower substrate and an upper substrate facing each other (S610). Thereafter, the composition for the optical bonding member is coated on the upper substrate, and the composition for the adhesive member is applied on the lower substrate protruded from the one surface of the upper substrate in the pad region (S620). Thereafter, the cover glass is pressed (S630) using an electrostatic chuck so that the composition for the adhesive member is brought into contact with the lower surface of the cover glass opposed to the substrate blank. In this case, the distance between the cover glass and the lower substrate can be reduced to a first distance. Thereafter, the composition for the adhesive member is cured (S640) so that the adhesive member is formed. In this case, the adhesive member may be cured to have a first thickness corresponding to the first distance. Thereafter, the electrostatic chuck is separated from the cover glass so that the composition for the optical adhesive member covers the entire surface of the upper substrate inside the dam member, and the process pressure is increased (S650). When the electrostatic chuck is detached, the cover glass can be raised by the restoring force of the dam member. Thus, the distance between the cover glass and the lower substrate can be increased to a second distance greater than the first distance. Thereafter, the air bubble between the composition for the optical bonding member and the cover glass is removed (S660), and the composition for the optical bonding member is cured (S670) so that the cover glass and the upper substrate of the substrate assembly are bonded. Thereafter, heat is applied to the adhesive member to reduce the elastic modulus of the adhesive member and increase the elongation of the adhesive member, or irradiation of the adhesive member with infrared rays (S680). In this case, the thickness of the adhesive member may be increased from the first thickness to a second thickness corresponding to the second distance.

As described above, the step of applying heat to the bonding member or irradiating infrared rays to the bonding member can be performed simultaneously with the step of curing the composition for the optical bonding member such that the cover glass and the upper substrate of the substrate assembly are bonded. That is, the adhesive member may be subjected to heat or infrared rays while the composition for the optical adhesive member is cured by heat or infrared rays. Thus, a secondary reaction of the adhesive member can be induced.

A method of manufacturing a liquid crystal display device according to an embodiment of the present invention cures a composition for an adhesive member before the electrostatic chuck is separated from the cover glass. That is, an adhesive member having rigidity is formed by a first-order reaction. Thus, even if the electrostatic chuck is separated from the cover glass, the adhesive member having a large elastic modulus and a small elongation can maintain the alignment of the cover glass and the substrate assembly constant, and the air bubble between the composition for the optical adhesive member and the cover glass can be removed Can be easily carried out. Therefore, the defective product generated in the manufacturing process of the liquid crystal display device can be reduced, and the productivity of the liquid crystal display device can be improved. Further, the method of manufacturing a liquid crystal display device according to an embodiment of the present invention reduces the elastic modulus of the adhesive member after the composition for the adhesive member is cured, or during the curing of the composition for the adhesive member, . That is, a secondary reaction can be performed to deform the rigid bonding member into a flexible bonding member. Thus, despite the rise of the cover glass due to the restoring force of the dam member, the lower substrate can be kept flat and the deformation of the lower substrate can be minimized. Therefore, light leakage due to deformation of the lower substrate can be minimized. On the other hand, since the adhesive member having completed the secondary reaction has a modulus of elasticity suitable for buffering the impact applied to the lower substrate, the impact applied to the lower substrate can be absorbed after the liquid crystal display is completed. Thus, the durability of the liquid crystal display device can be improved.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those embodiments and various changes and modifications may be made without departing from the scope of the present invention. . Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100, 200: liquid crystal display
110, 210: substrate assembly
111 and 211:
112, 212: upper substrate
113, 213: sealant
121, 221: Optical bonding member
122, 222: a dam member
130, 230: cover glass
140, 240: Display printed circuit board
150, 250: touch printed circuit board
160, 260:
423: Composition for optical adhesive member
461: Composition for adhesive member
LC: liquid crystal
ESC: electrostatic chuck
PA: pad area
NPA: non pad area
TP: pad portion
DI: Driving chip
SP / A: Separation area
O / A: overlap area
I / A: Interior space

Claims

A substrate assembly including a lower substrate and an upper substrate opposed to each other, the lower substrate protruding from one surface of the upper substrate in a pad region;
A cover glass facing the substrate assembly; And
Wherein the lower substrate and the cover glass are bonded to each other on the lower substrate of the substrate assembly protruding from the pad region so that deformation of the lower substrate is minimized even if the distance between the cover glass and the lower substrate is changed And the liquid crystal display device.

The method according to claim 1,
Wherein the thickness of the adhesive member changes to a thickness corresponding to a distance between the cover glass and the lower substrate when the distance between the cover glass and the lower substrate changes.

The method according to claim 1,
Wherein the adhesive member comprises:
An ultraviolet ray curable composition; And
And is formed of an additive which is mixed with the ultraviolet curing composition and reduces the elastic modulus of the adhesive member by heat or infrared rays and increases the elongation of the adhesive member.

The method of claim 3,
The UV-
Monofunctional acrylate-based monomers;
A polyfunctional epoxy acrylate oligomer containing at least two functional groups;
Photoinitiators; And
A silane-based compound that improves the adhesion of the ultraviolet-curable composition,
Wherein the additive is an ethoxyacrylate compound represented by the following formula (1).
[Chemical Formula 1]

5. The method of claim 4,
Wherein the additive is included in an amount of 10 wt% to 30 wt% based on the total weight of the ultraviolet curable composition and the additive.

5. The method of claim 4,
Wherein the adhesive member has a first modulus of elasticity and a first elongation at curing of the ultraviolet-curable composition,
The additive decreases the elastic modulus of the adhesive member in response to the heat or the infrared rays to a second elastic modulus smaller than the first elastic modulus and increases the elongation percentage of the adhesive member to a second elongation rate larger than the first elongation rate The liquid crystal display device.

The method according to claim 6,
The first elastic modulus is greater than or equal to 480 N / mm ² at room temperature (25 ° C), the second elastic modulus is from 100 N / mm ² to 170 N / mm ² at room temperature,
The first elongation is less than or equal to 90%, and the second elongation is greater than or equal to 300%.

The method according to claim 1,
Wherein the pad region of the lower substrate includes a driving chip region in which the driving chip is disposed and a touch pad region in which the touch pad is disposed on both sides of the driving chip region,
Wherein the adhesive member is disposed so as to partially overlap the touch pad area.

9. The method of claim 8,
An optical adhesive member disposed between the cover glass and the upper substrate; And
And a dam member surrounding the optical bonding member.

Forming a dam member on the upper substrate of a substrate assembly including a lower substrate and an upper substrate opposite to each other;
Applying a composition for an optical bonding member onto the upper substrate, and applying a composition for an adhesive member onto the lower substrate protruding from one surface of the upper substrate in a pad region;
Pressing the cover glass using an electrostatic chuck so that the composition for the adhesive member is brought into contact with the bottom surface of the cover glass facing the substrate assembly;
Curing the composition for the adhesive member so that the adhesive member is formed;
Separating the electrostatic chuck from the cover glass so that the composition for the optical bonding member covers the entire surface of the upper substrate inside the dam member, and raising the process pressure;
Removing air bubbles between the composition for the optical bonding member and the cover glass;
Curing the composition for the optical bonding member such that the cover glass and the upper substrate of the substrate assembly are bonded; And
And applying heat to the adhesive member or irradiating the adhesive member with infrared light so as to decrease the elastic modulus of the adhesive member and increase the elongation of the adhesive member.

11. The method of claim 10,
The step of pressing the cover glass using the electrostatic chuck such that the composition for the adhesive member is brought into contact with the bottom surface of the cover glass facing the substrate assembly may include reducing the distance between the cover glass and the lower substrate to a first distance , &Lt; / RTI >
Wherein the step of curing the composition for the adhesive member such that the adhesive member is formed comprises curing the composition for the adhesive member such that the adhesive member has a first thickness corresponding to the first distance, Gt;

12. The method of claim 11,
Separating the electrostatic chuck from the cover glass so that the composition for the optical bonding member covers the entire surface of the upper substrate inside the dam member, and raising the process pressure is performed so that the gap between the cover glass and the lower substrate Increasing the distance to a second distance greater than the first distance,
The step of applying heat to the adhesive member or irradiating infrared rays to the adhesive member so as to decrease the elastic modulus of the adhesive member and increase the elongation of the adhesive member may be performed by changing the thickness of the adhesive member from the first thickness To a second thickness corresponding to the second distance. &Lt; Desc / Clms Page number 19 >

11. The method of claim 10,
Curing the composition for the optical bonding member so that the cover glass and the upper substrate of the substrate assembly are adhered to each other; and heating the adhesive member to reduce the elastic modulus of the adhesive member and increase the elongation of the adhesive member Or the step of irradiating the adhesive member with infrared rays are performed simultaneously.