KR102467216B1 - Composite adhesive and display device having thereof - Google Patents

Abstract

The present invention relates to a composite adhesive including a first region where a (meth)acrylate-based resin is located and a second region where a siloxane-based resin is located, and a display device using the same. In the composite adhesive of the present invention, since the (meth)acrylate-based resin and the siloxane-based resin having different moduli are located in different regions, the low modulus of the (meth)acrylate-based resin and the high modulus of the siloxane-based resin are respectively used for adhesion. It is an adhesive with maximized physical properties such as properties and impact resistance. Therefore, the composite adhesive of the present invention can be used as, for example, an optically transparent adhesive capable of bonding a display panel and a cover window.

Description

Composite adhesive and display device including the same {COMPOSITE ADHESIVE AND DISPLAY DEVICE HAVING THEREOF}

The present invention relates to an adhesive applied to a display device, and more particularly, to an adhesive having improved adhesion reliability and impact-resistance, and a display device including the same.

As display technology develops, display devices such as Liquid Crystal Display (LCD) and Organic Light Emitting Device Display (OLED) are applied to computer monitors, TVs, displays of mobile phones and smart devices. . These display devices largely include a display panel that implements an image. In order to prevent the display panel from being damaged by external pressure, a cover window made of tempered glass or plastic material surrounds one or the entire surface of the display panel. have.

Among methods for attaching a cover window and a display panel, direct bonding is generally used. In the direct bonding method, an optically clear resin (OCR) or an optically clear adhesive (OCA) is used to harden OCR to bond the cover glass and the display panel.

1 is a cross-sectional view schematically illustrating a display device in which a cover window is attached to a display panel by applying a direct bonding method according to the prior art. As shown in FIG. 1 , the display device 1 includes a display panel 10, a cover glass 30 disposed outside the display panel 10, and the display panel 10 and the cover glass ( 20) includes an adhesive layer 20 applied and cured between. The adhesive layer 20 is typically an optically clear adhesive (OCA), and an optically clear resin (OCR) is used.

The adhesive layer 20 made of an optically transparent resin located between the display panel 10 and the cover window 30 improves the optical characteristics of the display device 1 and serves as a buffer against external impact. , the impact resistance should be improved. The optically transparent adhesive layer 20 interposed between the conventional display panel 10 and the cover window 30 mainly uses an optically transparent resin (OCR) such as an acrylate-based resin. An acrylate-based reactive component applied between the display panel 10 and the cover window 30 is cured and contracted to form the adhesive layer 20 , thereby reducing stress applied to the display panel 10 . In addition, the acrylate-based resin has a low modulus of elasticity, so that it can improve impact resistance.

Recently, a display device capable of realizing touch and at the same time being flexible, bending, and stretching has been demanded. The cover window 30, which was mainly made of conventional tempered glass, is also made of plastic, which is a flexible material. Compared to glass, plastic material has a soft property, so it bends on its own. In particular, plastic materials are vulnerable to heat, and thermal deformation occurs in a high temperature or high temperature and high humidity environment, resulting in unevenness on the surface.

In addition, currently, an acrylate-based resin is mainly used as an optically transparent resin applied between the display panel 10 and the cover window 30, and the acrylate-based resin has a curing shrinkage rate as high as about 3%. Therefore, when the acrylate-based resin is excessively cured or shrunk during the curing process, or when exposed to high temperature or high humidity conditions, the cover window 30 is bent and its flatness is lowered. In particular, as the temperature rises, the modulus of elasticity of the acrylate-based resin decreases, and thus the hardness decreases, resulting in a decrease in adhesive strength.

Therefore, as shown in FIG. 2 , the adhesive layer 20 made of acrylate-based resin cannot relieve stress applied from the cover window 30 under high temperature or high temperature and high humidity conditions, and thus the edge of the display panel 10 ), delamination of the adhesive layer 20 may occur.

The present invention has been proposed to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an adhesive that can have excellent flatness characteristics without deformation even in harsh environments of high temperature and high humidity, and a display device using the same. .

Another object of the present invention is to provide an adhesive having improved impact resistance and adhesive strength and a display device using the same.

According to one aspect of the present invention, the (meth) acrylate-based resin and the siloxane-based resin having different modulus values are configured in a composite form, and the (meth) acrylate-based resin is concentrated in the first region , A composite adhesive in which a siloxane-based resin is concentrated in a second region opposite to the first region is provided.

Using the curing characteristics of the (meth)acrylate-based resin and the siloxane-based resin, the (meth)acrylate-based resin and the siloxane-based resin may be concentrated in the first region and the second region, respectively.

Impact resistance applied to the cover window can be improved by performing a role as a buffer that reduces external impact by using the soft property (low elastic modulus) of the (meth)acrylate-based resin.

In addition, since the siloxane-based resin has a low curing shrinkage rate, good heat resistance, and excellent elastic modulus, it is possible to prevent the cover window from bending and to improve adhesion reliability.

According to another aspect of the present invention, a display device in which the aforementioned adhesive is positioned between a display panel and a cover window is provided.

In this case, the first area where the (meth)acrylate-based resin is located may be adjacent to the display panel, and the second area where the siloxane-based resin is located may be located adjacent to the cover window.

According to the present invention, an adhesive in the form of a composite material in which a (meth)acrylate-based resin and a siloxane-based resin having different modulus values are distributed in separate domains is proposed.

Since the siloxane-based resin has a low curing shrinkage rate, the stress applied to the cover window during curing is very low, and thus it is possible to prevent the cover window from being bent due to curing. In addition, since the region where the siloxane-based resin is distributed in the composite adhesive according to the present invention has a high elastic modulus (excellent elastic property), it holds the interface of the cover window to prevent the cover window from bending and maintain the flatness of the cover window. can

Since the siloxane-based resin has excellent heat resistance, the siloxane-based resin not only does not deform under high temperature or high temperature and high humidity conditions, but also maintains high elastic modulus. Therefore, since the adhesive strength of the adhesive positioned between the cover window and the display panel is maintained even under high temperature or high temperature and high humidity conditions, adhesion reliability may be improved under high temperature or high temperature and high humidity conditions.

In addition, since (meth)acrylate-based resin has a soft property (low modulus of elasticity), it can serve as a buffer to reduce external impact and improve impact resistance of the cover window.

In particular, the elastic modulus of the adhesive of the present invention gradually decreases from the region where the siloxane-based resin is located to the region where the (meth)acrylate-based resin is located. Therefore, when an external impact is applied, stress can be sufficiently relieved in the (meth)acrylate-based resin having a low elastic modulus. Since it maintains excellent adhesion and has excellent stress relaxation effect, it is possible to improve impact resistance.

1 is a cross-sectional view schematically illustrating a display device in which a cover window is attached to a display panel by applying a direct bonding method according to the prior art.
2 is a cross-sectional view schematically illustrating problems that occur when an acrylate-based adhesive is applied to a cover window and a display panel according to the prior art.
3A to 3C are views schematically illustrating a process of forming an adhesive composed of a composite material of a (meth)acrylate-based resin and a siloxane-based resin between a display panel and a cover window according to the present invention. FIG. 3A shows an application step, FIG. 3B shows a thermal curing step, and FIG. 3C shows a UV curing step, and schematically shows changes in components constituting the adhesive in each step.
4A and 4B are views schematically illustrating a display device in which the composite adhesive of the present invention is applied between a display panel and a cover window according to an exemplary embodiment of the present invention, respectively. FIG. 4A illustrates a display device in which a display panel and a cover window are directly attached, and FIG. 4B illustrates a display device in which a touch panel is interposed between the display panel and a cover window.
5 is a cross-sectional view schematically illustrating a liquid crystal panel as a display panel according to an exemplary embodiment of the present invention.
6a and 6b show graphs and analysis results of Py-GC/MS analysis results for composite adhesives synthesized according to the present invention. Figure 7a shows a graph and analysis results showing the Py-GC / MS analysis results for the silicon component. Figure 7b shows a graph and analysis results showing the Py-GC / MS analysis results for the acrylate component.
7A to 7C are images of changes in flatness of a panel in a high temperature and high humidity environment according to an exemplary embodiment of the present invention. Figure 7a is an image of the flatness of the panel before placing it in a high temperature and high humidity environment, Figure 7b is an image of the flatness after testing the panel to which the composite adhesive of the present invention is applied in a high temperature and high humidity environment, and Figure 7c is This is an image taken for flatness after testing a panel to which an acrylate adhesive according to the prior art is applied in a high temperature and high humidity environment.
8 is a graph showing hardness (hardness) measurement results using nano indentation analysis along the longitudinal section of the composite adhesive synthesized according to an exemplary embodiment of the present invention. As a comparative example, hardness measurement results analyzed along the longitudinal section of an adhesive composed of a double layer of an acrylate-based adhesive and a siloxane-based adhesive are also displayed.

According to one aspect of the present invention, the present invention is a (meth) acrylate-based resin is located in the first domain (domain) and; An adhesive composed of a composite material of a (meth)acrylate-based resin and a siloxane-based resin including a second domain in which a siloxane-based resin is located is provided.

In one exemplary embodiment, a third region in which a copolymer of a (meth)acrylate-based resin and a siloxane-based resin is positioned between the first region and the second region may be further included.

In this case, the thickness of the first region is preferably 2 to 8 times thicker than the thickness of the second region.

For example, the siloxane-based resin may be obtained by curing a siloxane-based compound having a silicon atom substituted with at least one C ₁ -C ₂₀ aliphatic functional group.

More specifically, the siloxane-based resin may be obtained by curing a cyclosiloxane compound having a silicon atom substituted with a C ₁ -C ₂₀ alkyl group or a C ₁ -C ₂₀ alkoxy group.

For example, the (meth)acrylate-based resin may be obtained by curing a light-reactive component, and the siloxane-based resin may be obtained by curing a heat-reactive component.

According to another aspect of the present invention, the present invention includes a display panel; a cover window disposed outside the display panel; an adhesive layer applied between the display panel and the cover window, wherein the adhesive layer includes: a first domain where a (meth)acrylate-based resin is located; A display device composed of a composite material of a (meth)acrylate-based resin and a siloxane-based resin including a second domain in which a siloxane-based resin is located is provided.

For example, the first area may be adjacent to the display panel and the second area may be adjacent to the cover window.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings when necessary.

The adhesive of the present invention is composed of a (meth)acrylate-based resin and a siloxane-based resin in the form of a composite material, and is designed so that the (meth)acrylate-based resin and the siloxane-based resin are located in two separate areas, respectively. Unless otherwise stated herein, the term (meth)acrylate refers to acrylate and (meth)acrylate collectively.

First, the composition and synthesis process of the composite adhesive according to the present invention will be described. 3A to 3C are views schematically illustrating a process of forming an adhesive 300 of the present invention between a display panel 200 and a cover window 400 of a display device according to an exemplary embodiment of the present invention, respectively. .

As shown in FIG. 3A, in order to form an adhesive (300, see FIG. 3C) composed of a (meth)acrylate-based resin and a siloxane-based resin in the form of a composite material, a reactive component that can be cured with these resins is mixed. The liquid adhesive composition 300a is coated on the cover window 400, and the cover window 400 coated with the adhesive composition 300a is bonded to the display panel 200.

The cover window 400 is located outside the side of the display panel 200 to be described below where an image is displayed, transmits the image of the display panel 200 as it is, and at the same time protects the display panel 200 from external impact or stress. . The cover window 400 may be injection molded from a material such as reinforced glass or reinforced plastic by, for example, an in-mold lamination method or a co-extrusion method. When flexible properties are required, the cover window 400 may be made of a plastic material.

The liquid adhesive composition 300a may be coated on one surface of the cover window 400 through various coating methods. For example, the liquid adhesive composition 300a is roll-coated, spin-coated, deep-coated, flow-coated, and spray coated. It can be coated on the cover window 400 by using. For example, it is coated to a thickness of about 100 to 200 μm using slit coating or flow coating to form the liquid adhesive layer 300a. Since the curing reaction has not yet proceeded in this step, a (meth)acrylate-based reactive component or a siloxane-based reactive component, which is a reactive component that can be cured in the liquid adhesive composition 300, is applied to the interface with the display panel 200 ( 302) and the cover window 400 and the interface 302 is uniformly distributed over the entire area.

The (meth)acrylate-based reactive component and/or the siloxane-based reactive component may be, for example, a light-reactive component curable by irradiation of a light source such as UV or a heat-reactive component curable by heat. In one exemplary embodiment, the (meth)acrylate-based reactive component may be a photoreactive component, and the siloxane-based reactive component may be a heat reactive component. In this case, depending on the difference in the curing mechanism or the application of the curing step, the siloxane-based reactive component may be first cured and located in a specific region in the thermal curing step described later, and the (meth)acrylate-based curable component in the subsequent UV curing step It can then be cured and placed in a region opposite to the siloxane-based reactive component.

Therefore, since the modulus of elasticity of the adhesive gradually increases or decreases along the longitudinal plane of the adhesive, impact due to external pressure can be alleviated, and thus impact resistance can be improved. In addition, (meth) acrylate-based resin and siloxane-based resin can be induced to be intensively distributed in a specific area. Accordingly, excellent heat resistance characteristics, low curing shrinkage characteristics, excellent hardness characteristics, and soft characteristics of (meth)acrylate-based resins of siloxane-based resins are exhibited to the maximum.

The (meth)acrylate-based reactive component may include a monomer or oligomer having an ethylenic double bond. In one exemplary embodiment, a (meth)acrylate-based reactive component having two or less acrylic functional groups may be used as the (meth)acrylate-based reactive component. In the case of using a (meth)acrylate-based reactive component having three or more acrylic functional groups, the shrinkage rate during the curing process is excessively large, which may cause defects such as yellow mura.

According to an exemplary embodiment, the (meth)acrylate-based reactive component is a C ₁ ~C ₂₀ alkyl group, a C ₂ ~C ₂₀ alkenyl group, a C ₂ ~C ₂₀ alkynyl group, a C ₁ ~C ₂₀ alkoxy group, a C ₁ an aliphatic (meth)acrylate-based reactive component substituted with a ~C ₂₀ alkoxyalkyl group, a C ₁ ~C ₂₀ alkoxyallyl group, an epoxy group, or the like; C ₅ -C ₈ cycloalkyl (meth)acrylic unsubstituted or substituted with a C ₁ -C ₁₀ alkyl group, C ₂ -C ₁₀ alkenyl group, C ₂ -C ₁₀ alkynyl group, or C ₁ -C ₁₀ alkoxy group rate-based reactive components; C ₅ to C ₂₀ aryl (meth)acrylates unsubstituted or substituted with a C ₁ -C ₁₀ alkyl group, C ₂ -C ₁₀ alkenyl group, C ₂ -C ₁₀ alkynyl group, or C ₁ -C ₁₀ alkoxy group based reactive components; an allyl alkoxylate-based reactive component having a C ₁ to C ₂₀ alkoxy group; And it may be selected from the group consisting of combinations thereof. For example, the (meth)acrylate-based reactive component is a C ₁ ~ C ₁₀ alkyl group, a C ₂ ~ C ₁₀ alkenyl group, a C ₁ ~ C ₂₀ alkoxy group, a C ₁ ~ C ₁₀ alkoxyalkyl group, or a C ₁ ~ C ₁₀ alkoxy group. (meth)acrylate-based monomers and/or oligomers having an allyl group, and/or allylalkoxylate-based monomers and/or oligomers having a C ₁ to C ₁₀ alkoxy group.

For example, the C ₁ ~C ₂₀ alkyl (meth)acrylate reactive component is methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2- Ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, iso-octyl (meth)acrylate, n-nonyl (meth)acrylate, iso-nonyl (meth)acrylate), n-decyl (meth)acrylate )Acrylate, iso-decyl (meth)acrylate, n-dodecyl (meth)acrylate, iso-dodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, amyl It may be selected from the group consisting of (meth)acrylates and combinations thereof, but the present invention is not limited thereto.

The C ₂ ~C ₂₀ alkenyl (meth)acrylate-based reactive component may be selected from the group consisting of octadiene (meth)acrylate, octadiene (meth)diacrylate, and combinations thereof, but the present invention Not limited to this.

The C ₁ ~C ₂₀ alkoxy (meth)acrylate reactive component is butadiene (meth)acrylate, hexadiene (meth)acrylate; 1,4-butanedioldi(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, ethylene glycol methyl ether (meth)acrylate, ethylene glycol phenyl ether (meth)acrylate, diethylene glycol methyl ether (meth)acrylate, diethylene glycol ethyl ether (meth)acrylate, 1,3-butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, It may be selected from the group consisting of diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, and combinations thereof, but the present invention is not limited thereto.

The C ₁ ~C ₂₀ alkoxyalkyl (meth)acrylate reactive component is 2-hydroxy-ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-hydroxy-propyl (meth)acrylate, 2-hydroxy-butyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, trimethoxybutyl (meth) acrylate, and combinations thereof It may be selected from the group, but the present invention is not limited thereto.

Epoxy (meth) acrylate-based reactive components include epoxy (meth) acrylate, epoxycyclohexylmethyl (meth) acrylate, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and combinations thereof. It may be selected from the group consisting of, but the present invention is not limited thereto.

The C ₅ -C ₈ cycloalkyl (meth)acrylate-based reactive component is from the group consisting of cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, and combinations thereof. may be selected, but the present invention is not limited thereto.

C ₅ ~ C ₂₀ aryl (meth) acrylate-based reactive components are benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate and these It may be selected from the group consisting of combinations, but the present invention is not limited thereto.

The allyl alkoxylate-based reactive component may be selected from the group consisting of allyl propoxylate, allyl monopropoxylate, and combinations thereof, but the present invention is not limited thereto.

The (meth)acrylate-based oligomer that can be used as the reactive component controls physical properties such as softness of the (meth)acrylate resin. As the (meth)acrylate-based oligomer component, two or more oligomer components having different molecular weights may be used in combination. For example, physical properties can be effectively controlled by using a first oligomer having a molecular weight of 500 to 900 and a second oligomer having a molecular weight of 1000 to 10000, preferably 1000 to 5000, in combination. Optionally, a first oligomer having a molecular weight of 500 to 3000 and a second oligomer having a molecular weight of 4000 to 50000 may be used in combination.

In an exemplary embodiment, the (meth)acrylate-based oligomer may be included in an amount of 30 to 70 parts by weight, preferably 40 to 60 parts by weight, in the liquid adhesive composition 300a. Unless otherwise stated in this specification, parts by weight refer to the weight ratio between the components to be formulated. If the content of the (meth)acrylate-based oligomer in the liquid adhesive composition (300a) is less than 30 parts by weight, the content of the (meth)acrylate-based monomer described later increases due to a decrease in viscosity, making it difficult to control physical properties. On the other hand, when the content of the (meth)acrylate-based oligomer exceeds 70 parts by weight, the viscosity is excessively high, which may cause problems in controlling the curing reaction rate and viscosity.

In one exemplary embodiment, the liquid adhesive composition 300a may further include a (meth)acrylate-based monomer. For example, the (meth)acrylate-based monomer, which is a light-reactive component, is for adjusting the reaction rate and viscosity. As a light-reactive component, the (meth)acrylate-based monomer is included in an amount of 5 to 20 parts by weight in the liquid adhesive composition 300a. When the content of the (meth)acrylate-based monomer is less than 5 parts by weight, the viscosity of the liquid adhesive composition 300a is too low, making it difficult to uniformly coat the cover window 400 with the liquid adhesive composition 300a. In addition, when the content of the (meth)acrylate-based monomer exceeds 20 parts by weight, the curing reaction rate may be slowed down.

Meanwhile, the liquid adhesive composition 300a of the present invention includes a siloxane-based reactive component in addition to the above-described (meth)acrylate-based reactive component. In one exemplary embodiment, the siloxane-based reactive component may be a thermally reactive component. A siloxane-based reactive component that can be cured into a siloxane-based resin by a curing reaction is a monomer and/or an oligomer constituting a unit of the siloxane-based resin.

In one exemplary embodiment, the siloxane-based reactive component is a siloxane-based compound having at least one silicon atom substituted with a C ₁ -C ₂₀ aliphatic chain. Non-limiting examples of the C ₁ -C ₂₀ aliphatic functional group that may be substituted on the silicon atom include a C ₁ -C ₂₀ alkyl group, a C ₂ -C ₂₀ alkenyl group, a C ₂ -C ₂₀ alkynyl group, and a C ₃ -C ₂₀ allyl group. , C ₁ -C ₂₀ alkoxy group. Preferably, it is a C ₁ -C ₂₀ alkyl group or a C ₁ -C ₂₀ alkoxy group. More specifically, the siloxane-based reactive component is a cyclosiloxane compound having a silicon atom substituted with a C ₁ -C ₂₀ alkyl group or a C ₁ -C ₂₀ alkoxy group.

These siloxane-based reactive components have poor compatibility or affinity with (meth)acrylate-based reactive components. Therefore, when these siloxane-based reactive components are cured, they are concentrated in a specific domain by a kind of phase separation from (meth)acrylate-based reactive components. Accordingly, the siloxane-based resin may be separated from the (meth)acrylate-based resin and located in a separate area.

Among cyclosiloxane compounds having a silicon atom substituted with a C ₁ -C ₂₀ alkyl group or a C ₁ -C ₂₀ alkoxy group, at least one C ₁ -C ₁₀ alkyl group, preferably a C ₁ -C ₅ alkyl group, is attached to the silicon atom. Substituted cyclosiloxane compounds are preferred. More preferably, it is a polyalkylcyclosiloxane compound in which two C ₁ -C ₁₀ alkyl groups, preferably C ₁ -C ₅ alkyl groups, are substituted on silicon atoms.

The polyalkylcyclosiloxane compound includes a polydimethylsiloxane (PDMS)-based cyclosiloxane in which two methyl groups are substituted for each silicon atom constituting a ring. Cyclosiloxane compounds of the PDMS series include hexamethylcyclosiloxane, octamethyltetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, tetradecamethylcycloheptasiloxane ( tetradecamethylcycloheptasiloxane), hexadecamethylcyclooctasiloxane, and combinations thereof, but the present invention is not limited thereto.

In one exemplary embodiment, the siloxane-based reactive component may be included in an amount of 10 to 20 parts by weight in the liquid adhesive composition 300a. If the content of the siloxane-based reactive component is less than 10 parts by weight, the formation of the siloxane-based resin is excessively reduced, so that it is difficult to expect improvement in heat resistance or elastic modulus. On the other hand, if the content of the siloxane-based reactive component exceeds 20 parts by weight, the elastic modulus of the finally prepared adhesive (300, see FIG. 3c) may be excessively high, resulting in deterioration in impact resistance.

In addition, a photoinitiator is included in the liquid adhesive composition 300a to induce a photopolymerization reaction of a (meth)acrylate-based reactive component, which may be, for example, a photoreactive component. For example, any photoinitiator capable of inducing a photopolymerization reaction of a (meth)acrylate-based reactive component by irradiation of an appropriate light source such as UV may be used as the photoinitiator. For example, commercial photoinitiators may be used, which may consist of Irgacure 184, Irgacure 819, and combinations thereof, but photoinitiators that may be used according to the present invention are by no means limited to these products.

For example, as usable photoinitiators, 1) 2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone, 2-hydroxy-2-methylpropiophenone, p-t-butyltrichloroacetophenone, p-t -Acetophenone-based photoinitiators such as butyldichloroacetophenone, 4-chloroacetophenone, 2,2'-dichloro-4-phenoxyacetophenone, 2) benzophenone, 4,4'-dimethylaminobenzophenone, 4,4 '-dichlorobenzophenone, 3,3'-dimethyl-2-methoxybenzophenone, 4-phenyl benzophenone, hydroxy benzophenone, acrylated benzophenone, 4,4'-bis(dimethylamino)benzophenone, 4, Benzophenone-based photoinitiators such as 4'-bis(diethylamino)benzophenone, 3) thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropyl thioxanthone, 1-[9-ethyl -6-(2-methylbenzoyl)-9H-carbazol-3-3-yl]-1-(O-acetyloxime), 2,4-diethyl thioxanthone, 2,4-diisopropyl thioxine Thioxanthone-based photoinitiators such as xanthon and 2-chlorothioxanthone, 4) Benzoin-based such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and benzyldimethyl ketal Photoinitiator, 5) 4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, bis(trichloromethyl)-6-styryl-s- Triazine, 2-4-trichloromethyl (piperonyl) -6-triazine, 2-4-trichloromethyl (4'-methoxystyryl) -6-triazine, 2- (3', 4 '-dimethoxy styryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4'-methoxy naphthyl) -4,6-bis (trichloromethyl) -s-tri Azine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-piphenyl-4,6-bis(trichloromethyl)-s-triazine, etc. of triazine-based photoinitiators.

The photoinitiator may be included in an amount of 0.01 to 10.0 parts by weight in the liquid adhesive composition 300a. When the content of the photoinitiator is less than 0.01 parts by weight, the curing reaction rate of the (meth)acrylate-based reactive component is too slow or the curing efficiency is reduced because the initiating role is not performed. If the content of the photoinitiator exceeds 10.0 parts by weight, yellowing may occur due to the ring structure characteristic of the photoinitiator that does not participate in curing.

In addition, a catalyst capable of accelerating thermal curing of the siloxane-based reactive component may be used in the liquid adhesive composition 300a of the present invention. Catalysts that can be used are platinum-based catalysts, for example divinyltetramethyl disiloxane Pt. The catalyst may be added in an amount of about 0.1 to about 5.0 parts by weight in the liquid adhesive composition 300a.

The cover window 400 coated on one surface with the liquid adhesive composition 300a is bonded to the display panel 400 (refer to FIG. 3A), and as shown in FIG. 3B, the cover window 400 is disposed below and displayed. Thermal curing is performed on the bonding panel with the panel 200 disposed thereon using a hot plate. Thermal curing may be performed at a temperature of 80 to 100 ° C for 5 to 20 minutes.

As described above, since the siloxane-based reactive component is a heat-reactive component, a siloxane-based resin having a network structure is formed by thermal curing. On the other hand, since the (meth)acrylate-based reactive component is a photoreactive component, it is hardly cured by thermal curing. The specific gravity of the siloxane-based resin forming the network structure by the curing reaction is greater than that of the uncured (meth)acrylate-based reactive component.

Accordingly, as the thermal curing proceeds, the siloxane-based reactive component having a relatively high specific gravity forms a network structure in a region adjacent to the interface 304 with the cover window 400 positioned below to form a siloxane-based resin. On the other hand, since the (meth)acrylate-based reactive component is not cured by thermal curing, its specific gravity is smaller than that of the siloxane-based resin. In addition, since the (meth)acrylate-based reactive component is not compatible with the siloxane-based reactive component and the siloxane-based resin cured therefrom, the opposite side of the interface 304 with the cover window 400 occupied by the siloxane-based resin It moves to the interface 302 with the display panel 200 . Meanwhile, an uncured unreacted siloxane-based reactive component and a (meth)acrylate-based reactive component coexist between the region occupied by the siloxane-based resin and the region occupied by the (meth)acrylate-based reactive component.

A phenomenon in which the siloxane-based resin and the (meth)acrylate-based reactive component are concentrated in the interface region 304 of the cover window 400 and the interface region 302 of the display panel 200 will be described in more detail. Since the network structure of the siloxane-based resin is relatively loose in the initial stage of the thermal curing reaction, some (meth)acrylate-based reactive components may be located between the network structures of the siloxane-based resin.

At this time, the (meth)acrylate-based reactive component cannot be located between all network structures formed by the siloxane-based resin, and a so-called free volume exists between the network structures formed by the siloxane-based resin. Due to the difference in compatibility between the siloxane-based resin cured by thermal curing and the (meth)acrylate-based reactive component, the (meth)acrylate-based reactive component does not occupy all the network structures formed by the siloxane-based resin. because it can't

However, when thermal curing continues, crosslinking between the siloxane-based reactive components is more densely formed, and the siloxane-based resin forms a dense network structure. A (meth)acrylate-based reactive component with poor compatibility cannot be positioned between the network structures formed by the dense siloxane-based resin. In other words, as the heat curing proceeds, the free volume between the network structures formed by the siloxane-based resin decreases, so that the (meth)acrylate-based reactive component escapes to the outside of the free volume. The specific gravity of the uncured (meth)acrylate-based reactive component is lower than that of the siloxane-based resin formed by thermal curing.

Therefore, as the thermal curing process proceeds and the network crosslinking of the siloxane-based resin is densely formed, the (meth)acrylate-based reactive component is formed in the upper first region, that is, the interface 302 with the display panel 200. ) area, and the siloxane-based resin is arranged in the lower second area, that is, the interface 304 area with the cover window 400.

When the thermal curing is completed, as shown in FIG. 3C , photocuring is performed using an appropriate light source while the display panel 200 is disposed below and the cover window 400 is disposed above. An appropriate light source (for example, UV or LED lamp) may be used for photocuring, whereby the (meth)acrylate-based reactive component, which is a photoreactive component, is cured. For example, photocuring may be performed by irradiating light with an intensity of about 3000 to 5000 J/cm 2 and may be performed for several seconds.

By photocuring, the (meth)acrylate-based component arranged in the first region adjacent to the interface 302 with the display panel 400 is cured to obtain a (meth)acrylate-based resin. Meanwhile, the siloxane-based resin formed by thermal curing is arranged in the second region adjacent to the interface 304 with the cover window 400 . On the other hand, as shown in FIG. 3B, when thermal curing proceeds and photocuring does not proceed, the uncured siloxane-based component and the (meth)acrylate-based component are present in the third region between the first region and the second region. coexist In the third region by photocuring, the siloxane-based component and the (meth)acrylate-based component are cured to form a (meth)acrylate-based resin-siloxane-based resin copolymer.

Therefore, in the adhesive 300 manufactured using the curing process of the present invention, the (meth)acrylate-based resin having a low elastic modulus is intensively arranged in the first region adjacent to the interface 302 with the display panel 200. The siloxane-based resin having a high elastic modulus is intensively arranged in the second region adjacent to the interface 304 with the cover window 400 . Since the (meth)acrylate-based resin and the siloxane-based resin form a copolymer, the third region between the first region and the second region has an elastic modulus value between the first region and the second region.

Due to the excellent heat resistance and good modulus characteristics of the siloxane-based resin concentrated on the cover window 400, deformation of the cover window 400 can be prevented, adhesion reliability can be improved, and the display panel 200 is concentrated. A display device capable of improving impact resistance can be manufactured by using the good soft characteristics of the (meth)acrylate-based resin. A display device to which the adhesive according to the present invention is applied will be described.

4A is a schematic cross-sectional view of a display device to which a composite adhesive according to an exemplary embodiment of the present invention is applied. As shown in FIG. 4A , the display device 100 largely includes a display panel 200, a cover window 400 located outside the display panel 200, and the display panel 200 and the cover window 400. It includes an adhesive layer 300 interposed therebetween. The display panel 200 may include any display panel capable of displaying images, such as a liquid crystal display panel and an organic light emitting display panel employing an organic light emitting diode.

Meanwhile, the cover window 400 may include a central substrate 410 and hard coating layers 412 and 414 for reinforcing the substrate 410 . The substrate 410 may be made of tempered glass, but may be made of a plastic material if a flexible display is to be implemented. The plastic substrate 410 constituting the cover window 400 is polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polycarbonate (PC), polycarbonate-polymethyl methacrylate (PC-PMMA), It may be made of a material such as polymethyl methacrylate-polycarbonate-polymethyl methacrylate (PMMA-PC-PMMA), and may be manufactured through a method of (co)extruding these polymer materials.

In general, since the cover window 400 is located at the outermost part of the display device 100, wear resistance is required to prevent external scratches such as nails or touch pens. Therefore, impact resistance should be improved to prevent the cover window 400 from being broken by an external impact. To this end, a hard type first hard coating layer 412 and a second hard coating layer 414 capable of implementing high hardness are formed on the upper and lower portions of the plastic substrate 410, respectively.

When only one side of the plastic substrate 410 is coated, warpage occurs in the plastic substrate 410, so it is preferable to coat a hard coating layer having the same thickness on the opposite side. For example, the hard coating layers 412 and 414 may be prepared using a urethane acrylic resin, a methacrylic resin, a silsesquioxane compound, or the like, and roll-coating, spin-coating, dip-coating, flow-coating, and the like It may be coated on the plastic substrate 410 using a method such as spray-coating. After the compound is coated on the substrate 410 , hard coating layers 412 and 414 may be formed by curing the compound with UV or the like. For example, the cover window 400 may have a total thickness of about 0.5 to 1.0 mm, and the hard coating layers 412 and 414 may each have a thickness of about 5 to 40 μm.

The adhesive layer 300 interposed between the display panel 200 and the cover window 400 has a first region 310 where (meth)acrylate-based resin is concentrated and disposed, and a second region 310 where siloxane-based resin is concentrated and disposed. It may be divided into a region 320 and a third region 330 in which a (meth)acrylate-based resin-siloxane-based resin is disposed between the first region 310 and the second region 32 . For example, the first area 310 is positioned adjacent to the display panel 200 and the second area 320 is positioned adjacent to the cover window 400 .

The siloxane-based resin intensively disposed in the second region 320 adjacent to the cover window 400 has a low curing shrinkage rate. Therefore, since the stress applied to the cover window 400 during the curing process of the siloxane-based resin is very low, the cover window 400 can be prevented from being bent due to curing. In particular, since the siloxane-based resin intensively disposed in the second region 320 has a high elastic modulus (excellent elastic property), it can firmly hold the interface 304 (see FIG. 3c) with the cover window 400. , the flatness of the cover window 400 may be maintained by preventing the cover window 400 from bending.

The Si-O binding energy of the siloxane-based compound is greater than the C-C and C-O binding energies included in the (meth)acrylate-based compound. Due to this, since the siloxane-based compound has high bonding stability, it has excellent heat resistance stability. In particular, the elastic modulus of the siloxane-based compound has an advantage of not having a large temperature dependence.

That is, since the siloxane-based resin disposed in the second region 320 has excellent heat resistance, the siloxane-based resin is not deformed under high temperature or high temperature and high humidity conditions and maintains high elastic modulus. Accordingly, since the adhesive strength of the adhesive 300 positioned between the cover window 400 and the display panel 200 is maintained even under high temperature or high temperature and high humidity conditions, adhesion reliability may be improved under high temperature or high temperature and high humidity conditions.

Meanwhile, since the (meth)acrylate-based resin intensively arranged in the first region 310 adjacent to the display panel 200 has a soft property (low modulus of elasticity), it serves as a buffer to reduce external impact. Thus, the impact resistance of the cover window 400 can be improved.

In particular, the adhesive layer 300 of the present invention has the lowest elastic modulus in the first region where the (meth)acrylate-based resin is concentrated, and the highest elastic modulus in the second region 320 where the siloxane-based resin is concentrated. The third region 330, in which the (meth)acrylate-based resin-siloxane-based resin copolymer is concentrated, has an intermediate elastic modulus. In other words, the elastic modulus of the adhesive layer 300 of the present invention gradually decreases from the first region 320 where the siloxane-based resin is located to the second region 310 where the (meth)acrylate-based resin is located. Therefore, when an external impact is applied, stress can be sufficiently relieved in the (meth)acrylate-based resin having a low elastic modulus.

As a result, by configuring the siloxane-based resin and the (meth)acrylate-based resin in the form of a composite material and arranging the siloxane-based resin and the (meth)acrylate-based resin in independent regions, excellent adhesive strength maintenance and stress relaxation effects are achieved. Since it is excellent, it is possible to improve impact resistance.

At this time, the thickness t1 of the first region 310 in which the (meth)acrylate-based resin is intensively arranged is 2 to 8 compared to the thickness t2 of the second region 320 in which the siloxane-based resin is intensively arranged. It may be formed twice as thick, preferably 3 to 7 times. When the thickness t1 of the first region 310 where the (meth)acrylate-based resin is located is 2 to 8 times thicker than the thickness t1 of the second region 320 where the siloxane-based resin is located, the external The external pressure applied from may be sufficiently relieved in the first region 310 to relieve stress.

For example, when the thickness t1 of the first region 310 is less than twice the thickness t2 of the second region 320, stress relief due to external pressure is insufficient and/or the entire adhesive layer 300 ) may cause defects such as yellow mura due to excessively high elastic modulus. On the other hand, when the thickness t1 of the first region 310 is more than 8 times thicker than the thickness t2 of the second region 320, the content of the siloxane-based resin is excessively small, resulting in a high content of the siloxane-based resin. It may be difficult to expect a deformation preventing effect or an improvement in adhesion reliability of the cover window 400 due to elastic modulus characteristics or heat resistance characteristics.

Meanwhile, the display device of the present invention may have a touch function, and FIG. 4B shows a display device 100' in which a touch panel 290, also referred to as a touch screen panel, is located between the display panel 200 and the adhesive layer 300. shows In FIG. 4B , the touch panel 290 is an on-cell type located above the display panel 200, but the touch panel 290 is an in-cell type located inside the display panel 200. (in-cell type).

As described above, the display panel 200 may be a liquid crystal display panel or an organic light emitting diode display panel. 5 is a cross-sectional view schematically illustrating a display panel 200 made of, for example, a liquid crystal display panel of a horizontal electric field type.

As shown in FIG. 5, in the display panel 200, a first substrate 201 and a second substrate 202 face each other, and a liquid crystal layer 230 is disposed between the substrates 201 and 202. is intervened. The first substrate 201 and the second substrate 202 may be made of plastic or glass, and a plurality of electrodes and wires are stacked on top of the first substrate 201 .

Looking more specifically at the plurality of electrodes and wires stacked on the top of the first substrate 201, a plurality of gate wires (not shown) extend in one direction on the top of the first substrate 201, and these A plurality of data lines 270 are formed in the second direction to define a plurality of pixel regions P by crossing a gate line (not shown). A gate pad (not shown) is formed in the non-display area by being connected to one end of a gate line (not shown), and a data pad (not shown) is formed in the non-display area by being connected to one end of the data line 270. .

In the plurality of pixel regions P, the semiconductor layer 266 including the gate electrode 262, the gate insulating layer 263, the active layer 266a and the ohmic contact layer 266b, and the source and drain electrodes 272 , 274) is formed. The gate electrode 262 is connected to a gate wire (not shown) and is formed on the first substrate 201 . A gate insulating film 263 made of an inorganic insulating material, which may be, for example, silicon oxide (SiOx) or silicon nitride (SiNx), is formed on the gate wiring (not shown) and the gate electrode 262 .

An active layer 266a made of pure amorphous silicon and an ohmic contact layer 266b formed on the active layer 266a and exposing the center of the active layer 266a and made of impurity amorphous silicon are formed on the gate insulating film 263. has been The active layer 266a and the ohmic contact layer 266b form the semiconductor layer 266 .

A source electrode 272 and a drain electrode 274 are formed on the semiconductor layer 266 and are spaced apart from each other to expose the center of the active layer 266a. The source electrode 272 is positioned on the semiconductor layer 266 and extends from the data line 270 , and the drain electrode 274 is positioned spaced apart from the source electrode 272 on the semiconductor layer 266 . The thin film transistor Tr is located in the switching region TrA.

In addition, on the gate insulating film 263, a data line 270 extending along the second direction is formed crossing the gate line (not shown). The data line 270 extends from the source electrode 272 of the thin film transistor Tr positioned in the pixel region P. Meanwhile, although not shown in the drawing, in one exemplary embodiment, a common wiring (not shown) is formed along a second direction parallel to the data wiring 270 on the gate insulating film 263, and the gate wiring (not shown) ) intersects with In an alternative embodiment, the common wiring (not shown) may be formed parallel to the gate wiring (not shown) on the same layer as the gate wiring (not shown).

Meanwhile, a first protective layer 264 is formed to cover the data wire 270, the source electrode 272, the drain electrode 274, and the common wire (not shown). A drain contact hole 275 exposing the drain electrode 274 of the thin film transistor Tr is formed in the first protective layer 264 . The first protective layer 264 may be an inorganic insulating film made of silicon oxide (SiOx) or silicon nitride (SiNx) or an organic insulating film made of photoacrylic. The first protective layer 264 prevents the ohmic contact layer 266b from being damaged in the process of forming the pixel electrode 276 .

Further, in each pixel region P, a pixel electrode 276 serving as a first electrode contacting and electrically connected to the drain electrode 274 of the thin film transistor Tr through the drain contact hole 275 is provided as a first protective layer. (264). The pixel electrode 276 is made of a transparent conductive material and may have a plate shape within each pixel region P. For example, the transparent conductive material may be indium-tin-oxide (ITO) or indium-zinc-oxide (IZO).

Although not shown, a gate pad electrode and a data pad electrode made of the same transparent conductive material as the pixel electrode 276 are formed in the non-display area above the first protective layer 264. The gate pad electrode is a gate It is electrically connected to the gate pad through a pad contact hole (not shown), and the data pad electrode is electrically connected to the data pad through a data pad contact hole (not shown).

A second passivation layer 280 as a second interlayer insulating film is formed on the pixel electrode 276 . The second protective layer 280 may be an inorganic insulating layer or an organic insulating layer.

Meanwhile, a common electrode 290 overlapping the plate-shaped pixel electrode 276 and having a plurality of slit-shaped holes (openings 292) is formed on the second protective layer 280. Like the pixel electrode 276, the common electrode 290 as the second electrode may be made of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO). The common electrode 290 is formed on the entire surface of the display area where the plurality of pixel areas P are formed. When a voltage is applied between the pixel electrode 276, which may be a plate-shaped first electrode, and the common electrode 290, which may be a second electrode having an opening 292, a fringe field is formed to form liquid crystal. By being driven, transmission efficiency is improved and high-quality images are displayed.

Although not shown, a black matrix, a light blocking member having an opening corresponding to each pixel region P, is formed on the lower part of the second substrate 202, which may be a color filter substrate, and the lower part of the black matrix and the black matrix are formed. A color filter layer is formed on the lower portion of the second substrate 202 exposed through the opening. The color filter layer (not shown) includes red, green, and blue color filters corresponding to the pixel region P. In addition, between the color filter layer (not shown) and the liquid crystal layer 230, an overcoat layer (not shown) of a material such as polyimide, polyacrylate, polyurethane, or the like is formed to protect the color filter layer (not shown) and flatten the surface. more can be formed.

Meanwhile, a polarizer 210 selectively transmitting only specific light is attached to the outside of the second substrate 202 . Although not shown in the drawings, a polarizer (not shown) is also attached to the outside of the first substrate 201 . In addition, a backlight unit may be provided to supply light from a rear surface of the transverse electric field type liquid crystal display panel 200 so that the difference in transmittance of the panel 200 is expressed to the outside. The cover window 400 and the display panel 200 are formed through the adhesive layer 300 (see FIG. 4A) interposed between the polarizer 210 attached to the outside of the second substrate 202 and the cover window 400 (see FIG. 4A). is coalesced

Hereinafter, the present invention will be described in more detail with reference to exemplary embodiments. However, the present invention is by no means limited to the invention described in the following examples.

Example 1: Manufacture of a display device formed with an adhesive in the form of a composite material

(Meth) acrylate-based photoreactive oligomer Butadiene acrylate 50 parts by weight, isobornyl acrylate 10 parts by weight, dipropylene glycol diacrylate 15 parts by weight (meth) acrylate-based photoreactive monomer 25 parts by weight, hexamethyl Cyclotrisiloxane, octamethyltetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, tetradecamethylcycloheptasiloxane, 15 parts by weight of a PDMS-based siloxane-based heat-reactive monomer combined with hexadecamethylcyclooctasiloxane, A liquid adhesive composition was prepared by mixing 9 parts by weight of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide as a UV initiator and 1 part by weight of divinlytetramethyl disolaxne Pt as a platinum catalyst.

A cover window was fabricated by flow-coating a urethane acrylic resin on the top and bottom of the plastic substrate, respectively. The liquid adhesive composition was applied to a thickness of 300 μm on the prepared cover window and bonded to the display panel. After adjusting the cover window to be positioned at the bottom, a heat curing process was performed at 80° C. for 20 minutes using a hot plate. The adhesive was completely cured by adjusting the display panel to be positioned at the lower side and irradiating with UV light having an intensity of 4000 mJ/cm 2 .

Comparative Example 1: Manufacture of a display device formed with an adhesive in the form of a composite material

A display device was manufactured by repeating the procedure of Example 1 except for using an adhesive composed only of an acrylate-based resin by curing only the acrylate-based reactive component.

Comparative Example 2: Manufacture of a display device formed with a double layer structure adhesive

A display device was manufactured by repeating the procedure of Example 1 except for using an adhesive having a double-layer structure of an adhesive layer composed only of an acrylate-based resin and an adhesive layer composed only of a siloxane-based resin.

Example 2: Analysis of adhesive components

Py-GC/MS analysis was performed on the prepared adhesive component to confirm the silicone component and residual acrylate-based component after curing. Figure 6a shows the measurement results and interpretation of the results according to the Py-GC / MS analysis of the adhesive region where the siloxane-based resin is located. A dimethoxydimethylsilane component decomposed by the PDMS component and a PDMS component used as a siloxane-based component in Example 1 were detected.

Figure 6b shows the measurement results and interpretation of the results according to the Py-GC / MS analysis of the adhesive region where the (meth) acrylate-based resin is located. An acrylate-based component and a photoinitiator component remaining due to the decomposition of the (meth)acrylate component remain partially. Based on these results, it was confirmed that the (meth)acrylate-based resin and the siloxane-based resin constituted a composite material according to Example 1.

Example 3: Evaluation of adhesion reliability

The display device fabricated in Example 1 was placed under high-temperature, high-humidity conditions (60° C./90% relative humidity), and changes in flatness and adhesive strength were measured. On the other hand, shear strength and tensile strength were measured in order to evaluate the adhesive strength of the adhesives prepared in Example 1 and Comparative Example 1, respectively.

Figure 7a is an image of the flatness of the panel before placing it in a high temperature and high humidity environment, Figure 7b is an image of the flatness after testing the panel to which the composite adhesive of the present invention is applied in a high temperature and high humidity environment, and Figure 7c is This is an image taken for flatness after testing a panel to which an acrylate adhesive according to the prior art is applied in a high temperature and high humidity environment. On the other hand, the flatness change amount, shear strength, and shear strength measurement results are shown in Table 1. Using the composite adhesive of Example 1, it was confirmed that the change in flatness could be prevented and the adhesive strength was greatly improved, thereby improving the adhesive reliability.

adhesive properties Example Flatness (mm) flatness change amount Shear strength (N/cm2) Tensile strength (N/cm2) before test 0.014 Example 1 0.062 0.048 ↑
(4.4 times increase) 50.1 35.1 Comparative Example 1 0.152 0.138 ↑
(10.8 times increase) 31.4 28.5

Example 4: Hardness measurement of adhesive

In order to measure the hardness related to the elastic modulus of the adhesive, the hardness was measured along the cross section of the composite adhesive prepared in Example 1 and the double-layer adhesive prepared in Comparative Example 2. Nano indentation analysis was performed along the longitudinal section, starting from the area adjacent to the display panel where (meth)acrylate-based resin, which is expected to have low hardness, is concentrated, to the area adjacent to the cover window, where siloxane-based resin, which is expected to have high hardness, is concentrated. measured through The hardness measurement result according to this embodiment is shown in FIG. 8 .

As shown in FIG. 8, it can be seen that the adhesive coated with the double layer in Comparative Example 2 has a unique hardness of each adhesive layer, and the hardness rapidly increased at the interface of the double layer. On the other hand, in the case of the adhesive prepared in the form of a composite material in Example 1, a hardness gradient occurred, showing low modulus in the area where the (meth)acrylate-based resin was concentrated, but the (meth)acrylate-based resin and The hardness gradually increased from the middle region of the siloxane-based resin, and the highest hardness was shown in the region where the siloxane-based resin was concentrated.

In the above, the present invention has been described based on exemplary embodiments and examples of the present invention, but the present invention is not limited to the technical idea described in the above embodiments and examples. Rather, those skilled in the art to which the present invention pertains can easily make various modifications and changes based on the embodiments and examples described above. However, the fact that all such modifications and changes fall within the scope of the present invention will become more apparent through the appended claims.

100, 100': display device 200: display panel
290: touch panel 300: adhesive
310: first area 320: second area
330: third area 400: cover window
410: substrate 420, 430: hard coating layer

Claims (22)

a first domain in which (meth)acrylate-based resin is located;
a second domain in which a siloxane-based resin is located;
A third region in which a copolymer of a (meth)acrylate-based resin and a siloxane-based resin is positioned between the first region and the second region
An adhesive comprising a (meth) acrylate-based resin and a siloxane-based resin in the form of a composite.
delete According to claim 1,
The thickness of the first region is 2 to 8 times thicker than the thickness of the second region.
According to claim 1,
The siloxane-based resin is an adhesive obtained by curing a siloxane-based compound having at least one silicon atom substituted with a C ₁ -C ₂₀ aliphatic functional group.
According to claim 1,
The siloxane-based resin is an adhesive obtained by curing a cyclosiloxane compound having a silicon atom substituted with a C ₁ -C ₂₀ alkyl group or a C ₁ -C ₂₀ alkoxy group.
According to claim 1,
The (meth)acrylate-based resin is obtained by curing a light-reactive component, and the siloxane-based resin is obtained by curing a heat-reactive component.
a display panel;
a cover window disposed outside the display panel;
an adhesive layer applied between the display panel and the cover window;
The adhesive layer includes a first domain in which (meth)acrylate-based resin is located; a second domain in which a siloxane-based resin is located; Composed of a composite material of a (meth)acrylate-based resin and a siloxane-based resin including a third region in which a copolymer of a (meth)acrylate-based resin and a siloxane-based resin is positioned between the first region and the second region display device.
delete According to claim 7,
The display device of claim 1 , wherein a thickness of the first region is 2 to 8 times thicker than a thickness of the second region.
According to claim 7,
The siloxane-based resin is a display device obtained by curing a siloxane-based compound having at least one silicon atom substituted with a C ₁ -C ₂₀ aliphatic functional group.
According to claim 7,
The siloxane-based resin is a display device obtained by curing a cyclosiloxane compound having a silicon atom substituted with a C ₁ -C ₂₀ alkyl group or a C ₁ -C ₂₀ alkoxy group.
According to claim 7,
The (meth)acrylate-based resin is obtained by curing a light-reactive component, and the siloxane-based resin is obtained by curing a heat-reactive component.
According to claim 7,
The first area is adjacent to the display panel, and the second area is adjacent to the cover window. a first domain in which (meth)acrylate-based resin is located;
It includes a second domain in which a siloxane-based resin is located,
The thickness of the first region is 2 to 8 times thicker than the thickness of the second region and is composed of a composite material of a (meth)acrylate-based resin and a siloxane-based resin.
a first domain in which (meth)acrylate-based resin is located;
It includes a second domain in which a siloxane-based resin is located,
The siloxane-based resin is composed of a composite form of a (meth)acrylate-based resin and a siloxane-based resin obtained by curing a siloxane-based compound having a silicon atom substituted with at least one C ₁ -C ₂₀ aliphatic functional group Adhesive.
a first domain in which (meth)acrylate-based resin is located;
It includes a second domain in which a siloxane-based resin is located,
The siloxane-based resin is a composite form of a (meth)acrylate-based resin and a siloxane-based resin obtained by curing a cyclosiloxane compound having a silicon atom substituted with a C ₁ -C ₂₀ alkyl group or a C ₁ -C ₂₀ alkoxy group. An adhesive composed of.
a first domain in which (meth)acrylate-based resin is located;
It includes a second domain in which a siloxane-based resin is located,
The (meth)acrylate-based resin is obtained by curing a light-reactive component, and the siloxane-based resin is an adhesive composed of a composite material of a (meth)acrylate-based resin obtained by curing a heat-reactive component and a siloxane-based resin. .
a display panel;
a cover window disposed outside the display panel;
an adhesive layer applied between the display panel and the cover window;
The adhesive layer includes a first domain in which (meth)acrylate-based resin is located; It includes a second domain where the siloxane-based resin is located, and the thickness of the first domain is 2 to 8 times thicker than the thickness of the second domain in the form of a composite of (meth)acrylate-based resin and siloxane-based resin. configured display device.
a display panel;
a cover window disposed outside the display panel;
an adhesive layer applied between the display panel and the cover window;
The adhesive layer includes a first domain in which (meth)acrylate-based resin is located; A (meta) siloxane-based resin is obtained by curing a siloxane-based compound having a silicon atom substituted with at least one C ₁ -C ₂₀ aliphatic functional group and including a second domain where the siloxane-based resin is located. A display device composed of a composite material of acrylate-based resin and siloxane-based resin
a display panel;
a cover window disposed outside the display panel;
an adhesive layer applied between the display panel and the cover window;
The adhesive layer includes a first domain in which (meth)acrylate-based resin is located; It includes a second domain where a siloxane-based resin is located, and the siloxane-based resin is used for curing a cyclosiloxane compound having a silicon atom substituted with a C ₁ -C ₂₀ alkyl group or a C ₁ -C ₂₀ alkoxy group. A display device composed of a composite material of a (meth)acrylate-based resin and a siloxane-based resin obtained by
a display panel;
a cover window disposed outside the display panel;
an adhesive layer applied between the display panel and the cover window;
The adhesive layer includes a first domain in which (meth)acrylate-based resin is located; It includes a second domain in which a siloxane-based resin is located, the (meth)acrylate-based resin is obtained by curing a light-reactive component, and the siloxane-based resin is obtained by curing a heat-reactive component (meta) ) An adhesive composed of a composite material of acrylate-based resin and siloxane-based resin.
a display panel;
a cover window disposed outside the display panel;
an adhesive layer applied between the display panel and the cover window;
The adhesive layer includes a first domain in which (meth)acrylate-based resin is located; It includes a second domain in which a siloxane-based resin is positioned, the first domain is adjacent to the display panel, and the second domain is positioned adjacent to the cover window. A display device composed of a composite material of acid-based resin.

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