WO2020159144A1

WO2020159144A1 - Touch sensor laminate and image display device

Info

Publication number: WO2020159144A1
Application number: PCT/KR2020/001063
Authority: WO
Inventors: 김지연; 이명원; 탁광용
Original assignee: 동우화인켐 주식회사
Priority date: 2019-01-28
Filing date: 2020-01-22
Publication date: 2020-08-06

Abstract

A touch sensor laminate according to embodiments of the present invention comprises: a lower structure; a touch sensor layer laminated on the lower structure; a pressure-sensitive adhesive layer laminated on the touch sensor layer and having a Young's modulus of 0.05 to 1 MPa; and an optical layer laminated on the pressure-sensitive adhesive layer. The touch sensor laminate satisfies a predetermined thickness ratio and has improved folding durability.

Description

Touch sensor stack and image display device

The present invention relates to a touch sensor stack and an image display device. More specifically, the present invention relates to a touch sensor stack and an image display device including a touch sensor layer and an optical layer.

With the recent development of the information society, demands for the display field have been presented in various forms. For example, various flat panel display devices having characteristics such as thinning, lightening, and low power consumption, for example, a liquid crystal display device, a plasma display panel device, Electroluminescent display devices, organic light-emitting diode display devices, and the like have been studied.

On the other hand, a touch panel, which is an input device attached to the display device and capable of selecting a user's hand or an object and inputting a user's command by selecting an instruction displayed on the screen, is combined with a display device to display an image. And electronic devices in which information input functions are implemented together.

In addition, recently, as flexible displays that can be folded or bent have been developed, touch panels applied to the flexible displays also need to be developed to have flexibility.

However, conductive structures such as sensing electrodes and insulating structures in the touch panel are distributed in the same layer or in different layers, and when folding or bending occurs, defects such as electrode cracks and electrode peeling may occur.

For example, Korean Patent Registration No. 10-1923438 discloses an image display device in which a touch panel is combined, but as described above, adjustment of flexible characteristics is not considered.

One object of the present invention is to provide a touch sensor stack having improved flexibility and mechanical reliability.

One object of the present invention is to provide an image display device having improved flexibility and mechanical reliability.

1. Substructure; A touch sensor layer stacked on the lower structure; A point adhesive layer laminated on the touch sensor layer and having a Young's Modulus of 0.05 to 1 MPa; And an optical layer laminated on the point adhesive layer, wherein the thickness ratio represented by Equation 1 below is 12 to 23%, and the touch sensor laminate:

[Equation 1]

|A-B|*100/B (%)

(In formula 1, A is the height from the upper surface of the optical layer to the interface of the touch sensor layer and the point adhesive layer, B is 1/2 of the total thickness of the touch sensor laminate).

2. In the above 1, the thickness ratio is 17.7 to 21%, the touch sensor laminate.

3. In the above 1, the Young's modulus of the point adhesive layer is 0.05 to 0.25 MPa, the touch sensor laminate.

4. In the above 1, the peel strength of the point adhesive layer to the touch sensor layer is 5 to 10 N/25mm, the touch sensor laminate.

5. The touch sensor laminate according to the above 1, wherein the lower structure includes a lower substrate and a lower point adhesive layer formed between the lower substrate and the touch sensor layer.

6. In the above 5, wherein the lower substrate comprises a flexible display panel, a touch sensor stack.

7. In the above 1, wherein the optical layer comprises a coated polarizer or a polarizing plate, a touch sensor laminate.

8. In the above 1, the center surface corresponding to 1/2 of the total thickness of the touch sensor stack is included in the touch sensor layer, the touch sensor stack.

9. Flexible display panel; A touch sensor layer stacked on the flexible display panel; A point adhesive layer laminated on the touch sensor layer and having a Young's Modulus of 0.05 to 1 MPa; And an optical layer laminated on the point adhesive layer, wherein the thickness ratio represented by the following Equation 1 is 12 to 23%, an image display device:

[Equation 1]

|A-B|*100/B (%)

(In formula 1, A is the height from the upper surface of the optical layer to the interface of the touch sensor layer and the point adhesive layer, B is 1/2 of the total thickness of the image display device).

10. The image display device according to the above 9, further comprising a window substrate stacked on the optical layer.

11. In the above 9, the thickness ratio is 17.7 to 21%, the Young's modulus of the adhesive layer is 0.05 to 0.25 MPa, the image display device.

In the touch sensor laminate according to the embodiments of the present invention, by adjusting the overall thickness of the laminate including the touch sensor layer, and the thickness of the optical layer and the adhesive layer, the electrode crack of the touch sensor layer during folding, electrode damage It is possible to prevent a touch sensing defect due to the like.

In addition, by adjusting the Young's modulus of the point adhesive layer together, it is possible to further improve mechanical reliability in the touch sensor layer when folding is repeated.

The touch sensor stack can be effectively applied to a flexible display having improved flexibility and operational reliability.

1 is a schematic cross-sectional view showing a touch sensor stack according to example embodiments.

2 and 3 are schematic plan and cross-sectional views, respectively, showing a structure of a touch sensor layer included in a touch sensor stack according to example embodiments.

Fig. 4 is a schematic cross-sectional view showing an image display device according to example embodiments.

Embodiments of the present invention includes a lower structure, a touch sensor layer, a point adhesive layer, and an optical layer, and provide a touch sensor laminate and an image display device having improved flexibility and durability.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the following drawings attached to this specification are intended to illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention together with the contents of the present invention, the present invention is described in such drawings It should not be interpreted as being limited to the matter.

Referring to FIG. 1, the touch sensor stack may include a touch sensor layer 130, a point adhesive layer 140 and an optical layer 150 sequentially stacked on the lower structure 100.

The lower structure 100 may include an object on which the touch sensor layer 130 is stacked, a base layer, a base layer, and a substrate. In example embodiments, the lower structure 100 includes the lower substrate 110 and may include a lower point adhesive layer 120 formed between the lower substrate 110 and the touch sensor layer 130.

The lower structure 100 or the lower substrate 110 may include a single-layer structure or a multi-layer structure. For example, the lower structure 100 may include a plurality of insulating layers or insulating structures, and may also include a multilayer structure of an insulating layer and a conductive layer.

The lower substrate 110 may include a flexible substrate or flexible panel having flexibility. According to example embodiments, the lower substrate 110 may include a flexible display panel.

The lower point adhesive layer 120 may include, for example, an optical clear adhesive (OCA) material known in the field of electronic materials.

The touch sensor layer 130 may include a plurality of sensing electrodes and an insulating layer. The structure and structure of the touch sensor layer 130 will be described later in more detail with reference to FIGS. 2 and 3.

The point adhesive layer 140 may include, for example, an acrylic or silicone pressure sensitive adhesive material. For example, the point adhesive layer 140 is applied to the surface of the touch sensor layer 130 or the optical layer 140 by applying a point adhesive composition comprising an acrylate-based copolymer and/or monomer, crosslinking agent, and solvent to photocuring. Can be formed.

The crosslinking agent may include, for example, an isocyanate crosslinking agent. The point adhesive composition may further include additional components such as a silane coupling agent and an antistatic agent.

The optical layer 150 may be bonded to the touch sensor layer 130 through the point adhesive layer 140. The optical layer 150 may include a polarization layer, a retardation layer, a brightness enhancement layer, a refractive index matching layer, etc., included in the image display device for image improvement. According to exemplary embodiments, the optical layer 150 may include a polarizing layer, for example, a coating type polarizer or a polarizing plate.

The coated polarizer may include a liquid crystal coating layer including a polymerizable liquid crystal compound and a dichroic dye. In this case, the optical layer 150 may further include an alignment layer for imparting alignment to the liquid crystal coating layer.

For example, the polarizing plate may include a polyvinyl alcohol-based polarizer and a protective film attached to at least one surface of the polyvinyl alcohol-based polarizer.

In FIG. 1, 1/2 of the entire thickness of the touch sensor stack is denoted by B, and the touch sensor layer 130 and the point from the top surface of the touch sensor stack (for example, the top surface of the optical layer 150 ). The height to the interface of the adhesive layer 140 is indicated by A.

The thickness ratio of the touch sensor stacked body represented by the following Equation 1 may be adjusted within a predetermined range.

[Equation 1]

|A-B|*100/B (%)

According to example embodiments, the thickness ratio value of the touch sensor laminate represented by Equation 1 below may be about 12 to 23%. Durability can be secured when folded or folded through the balance of the thicknesses of the upper and lower portions of the touch sensor stack within the thickness ratio.

In addition, the Young's Modulus of the point adhesive layer 140 may satisfy a range of about 0.05 to 1 MPa. For example, when the Young's modulus of the adhesive layer 140 is less than about 0.05 MPa, the strength of the adhesive layer 140 is excessively lowered, so that sufficient shock absorption for the touch sensor layer 120 may not be implemented. When the Young's modulus of the adhesive layer 140 exceeds about 1 MPa, sufficient flexibility and elasticity may not be implemented from the adhesive layer 140.

The Young's modulus of the adhesive layer 140 may be adjusted, for example, by changing the content of the crosslinking agent, the curing time for photocuring, or the amount of light irradiation.

According to exemplary embodiments, by adjusting the thickness ratio of the touch sensor laminate and the Young's modulus of the point adhesive layer 140 together, while securing sufficient flexible properties, mechanical stability in the touch sensor layer 130 during folding or bending is secured. You can improve together.

Preferably, the thickness ratio of the touch sensor layered body represented by Equation 1 below may be about 17.7 to 21%. In addition, the point adhesive layer 140 may have a Young's modulus of about 0.05 to 0.25 MPa.

In some embodiments, a central surface M corresponding to 1/2 of the total thickness of the touch sensor stack may be included in the touch sensor layer 130 as indicated by a dotted line in FIG. 1. Accordingly, stress in the touch sensor layer 130 is effectively dispersed, so that fractures and cracks of electrodes in the touch sensor layer 130 can be suppressed.

In some embodiments, the peel strength of the point adhesive layer 140 to the touch sensor layer 130 may be about 5 to 10 N/25 mm. When folding stress is applied to the touch sensor stack within the above range, the folding stress can be sufficiently dispersed within the point adhesive layer 140 without causing peeling of the touch sensor layer 130. Therefore, it is possible to more effectively suppress the electrode crack in the touch sensor layer 130.

2 and 3 are schematic plan and cross-sectional views, respectively, showing a structure of a touch sensor layer included in a touch sensor stack according to example embodiments. Specifically, FIG. 3 is a cross-sectional view taken along line I-I' of FIG. 2.

2 and 3, the touch sensor layer 130 may include sensing electrodes arranged on the support layer 50.

The support layer 50 is, for example, cyclic olefin polymer (COP), polyethylene terephthalate (PET), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS) ), polyallylate, polyimide (PI), cellulose acetate propionate (CAP), polyethersulfone (PES), cellulose triacetate (TAC), polycarbonate (PC), cyclic olefin copolymer (COC) ), polymethyl methacrylate (PMMA), and the like.

The sensing electrodes may include sensing electrodes arranged in different directions on a plane. For example, the first sensing electrode 60 (eg, arranged along the X direction) and the second sensing electrode 70 (eg, arranged along the Y direction) may be arranged to cross each other.

The first sensing electrode 60 and the second sensing electrode 70 may provide information about X coordinates and Y coordinates of the touched point, respectively. For example, when a human hand or an object is input over the touch sensor stack, an electrical signal may be generated by a change in capacitance through the first sensing electrode 60 and the second sensing electrode 70. The electrical signal may be transmitted to the driving circuit side, for example, via a position detection line.

The second sensing electrodes 70 may have an island shape spaced apart from each other. Meanwhile, the first sensing electrodes 60 may be integrally connected to each other through the connecting portion 65 along the row direction (eg, X direction).

When the first sensing electrode 60 and the second sensing electrode 70 are disposed on the same level as each other, the second sensing electrodes 70 are insulated from the first sensing electrode 600 and bridged to connect to each other The electrode 75 may be further formed. The bridge electrode 75 may electrically connect the second sensing electrodes 70 adjacent to each other in the column direction (eg, the y direction).

As illustrated in FIG. 3, the insulating layer 80 may at least partially cover the

sensing electrodes

60 and 70. In some embodiments, the insulating layer 80 covers the first sensing electrode 60 or the connection part 65, and partially covers the second sensing electrodes 70. For example, the insulating layer 80 may include a contact hole partially exposing the upper surface of the second sensing electrode 70.

The insulating layer 80 may be formed of a transparent insulating material. For example, the insulating layer 80 may be formed using an inorganic insulating material such as silicon oxide or a transparent organic material such as acrylic resin.

The bridge electrode 75 is disposed on the insulating layer 80 to electrically connect a pair of neighboring second sensing electrodes 70 to each other. For example, the bridge electrode 75 may intersect the connecting portion 65 on the insulating layer 80. The bridge electrode 75 may fill the contact holes formed in the insulating layer 80.

Sensing electrodes

60 and 70 and bridge electrode 75 may include a transparent conductive oxide or metal. The transparent conductive oxide may include, for example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), and the like. The metal is, for example, silver (Ag), gold (Au), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), chromium (Cr), titanium (Ti), tungsten (W) ), niobium (Nb), tantalum (Ta), vanadium (V), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), tin (Sn) or alloys thereof It may include.

In some embodiments, the

sensing electrodes

60 and 70 and/or the bridge electrode 75 may have a multi-layer structure. For example, the

sensing electrodes

60 and 70 and/or the bridge electrode 75 may have a structure in which a transparent oxide layer and a metal layer are stacked.

In some embodiments, the first sensing electrode 60 and the second sensing electrode 70 may be formed at different levels. For example, either the first sensing electrode 60 or the second sensing electrode 70 may be formed on the insulating layer 80 and the other under the insulating layer 80. In this case, the bridge electrode 75 may be omitted, and both the first sensing electrode 60 and the second sensing electrode 70 may include connections.

In some embodiments, the sensing electrodes may be formed as independent island patterns, respectively, and provided as individual sensing domains.

For example, in the touch sensor stack illustrated in FIG. 1, the lower substrate 110 may include a flexible display panel. In this case, for example, a flexible display device as illustrated in FIG. 4 can be implemented.

Referring to FIG. 4, the image display device includes a lower point adhesive layer 120, a touch sensor layer 130, a point adhesive layer 140 and an optical layer 150 sequentially stacked on the flexible display panel 110a. can do.

The flexible display panel 110a includes a pixel electrode 210, a pixel defining layer 220, a display layer 230, a counter electrode 240, and an encapsulation layer 250 disposed on the panel substrate 200. can do.

A pixel circuit including a thin film transistor (TFT) is formed on the panel substrate 200, and an insulating film covering the pixel circuit may be formed. The pixel electrode 210 may be electrically connected to the drain electrode of the TFT, for example, on the insulating film.

The pixel defining layer 220 is formed on the insulating layer to expose the pixel electrode 210 to define a pixel area. The display layer 230 is formed on the pixel electrode 210, and the display layer 230 may include, for example, a liquid crystal layer or an organic emission layer.

The counter electrode 240 may be disposed on the pixel defining layer 220 and the display layer 230. The counter electrode 240 may be provided as, for example, a common electrode or cathode of the image display device. An encapsulation layer 250 for protecting the flexible display panel 110a may be stacked on the counter electrode 240.

Even in the image display device, the thickness ratio value of Equation 1 described above may be satisfied. Also, in the image display device, the point adhesive layer 140 may have a Young's modulus in the above-described range.

In some embodiments, the window substrate 170 may be stacked on the optical layer 150 through the upper point adhesive layer 320.

The window substrate 170 includes, for example, a hard coating film, and in one embodiment, a light blocking pattern 175 may be formed on a peripheral portion of one surface of the window substrate 170. The light blocking pattern 175 may include, for example, a color print pattern, and may have a single-layer or multi-layer structure. The bezel part or the non-display area of the image display device may be defined by the light blocking pattern 175.

Hereinafter, experimental examples are provided to help understanding of the present invention, but the following experimental examples are merely illustrative of the present invention and do not limit the scope of the appended claims, and examples within the scope and technical scope of the present invention. It is apparent to those skilled in the art that various changes and modifications to the present invention are possible, and it is natural that such modifications and modifications fall within the scope of the appended claims.

실험예: 폴딩 내구성 평가Experimental Example: Evaluation of folding durability

A touch sensor laminate of Examples and Comparative Examples having a thickness ratio in Table 1 below and sequentially stacked PET film-OCA layer-touch sensor layer-point adhesive layer (PSA layer)-polarizing plate was prepared.

The Young's modulus of the adhesive layer was adjusted by changing the light irradiation amount and the light irradiation time for curing the PSA layer. The Young's Modulus of the point adhesive layer used in each touch sensor laminate was measured using an AG-Xplus tester (Shimadzu).

Specifically, a sample cut into a 20 mm×50 mm rectangle of the PSA layer was fixed to the clamp of the AG-Xplus tester. Thereafter, the sample was fixed so that the quasi-length of the sample to be pulled was 5 cm, and the Young's modulus was measured in a state of pulling up at a tensile rate of 20 mm/min under an environment of 23° C. and 55% relative humidity.

The peel strength of the adhesive layer to the touch sensor was measured using AG-IS (manufactured by Shimadzu Corporation). Specifically, after attaching the point adhesive layer on the touch sensor, a sample was prepared by cutting to a size of 150 mm × 25 mm using a super cutter. A lead wire was made on the point adhesive layer of the cut sample, and the lead wire was fixed to the upper clamp. The touch sensor was fixed to the lower clamp. Thereafter, as the upper clamp was moved, the adhesive layer was peeled 180 degrees to measure the peel strength. Peel strength was obtained through the average value of the remaining sections except for the initial 20% section.

Folding each of the touch sensor stacks of the examples and comparative examples using the CFT-120 (Cobotech Co., Ltd.) equipment so that the outer surface of the display panel is folded convexly to the outside with a radius of curvature of 2R to 5R. The folding durability was evaluated by repeating as follows.

S: Normal operation of touch sensor function after folding more than 200,000 times

◎: Normal operation of the touch sensor function after folding from 150,000 to less than 200,000 times

○: Normal operation of the touch sensor function after folding from 50,000 to 100,000 times

△: Normal touch sensor after folding 10,000 times, bad touch sensor after folding 20,000 times

×: Poor touch sensor operation after folding 10,000 times

The evaluation results are shown in Table 1 below. In Table 1, the thickness of each layer was described in the order of polarizing plate-PSA layer-touch sensor layer-OCA layer-PET film.

Referring to Table 1, when the thickness ratio and the Young's modulus of the point adhesive layer according to the exemplary embodiments described above are satisfied, a normal touch sensing function is implemented even when folding is over 50,000 times. On the other hand, as shown in the comparative example, when at least one of the thickness ratio and the Young's modulus of the adhesive layer is not satisfied, the folding durability is rapidly reduced.

Claims

Substructures;

A touch sensor layer stacked on the lower structure;

A point adhesive layer laminated on the touch sensor layer and having a Young's Modulus of 0.05 to 1 MPa; And

It includes an optical layer laminated on the point adhesive layer,

A touch sensor laminate having a thickness ratio of 12 to 23% represented by Equation 1 below:

[Equation 1]

|A-B|*100/B (%)

(In formula 1, A is the height from the upper surface of the optical layer to the interface of the touch sensor layer and the point adhesive layer, B is 1/2 of the total thickness of the touch sensor laminate).
The method according to claim 1, The thickness ratio is 17.7 to 21%, the touch sensor laminate.
The method according to claim 1, Young's modulus of the point adhesive layer is 0.05 to 0.25 MPa, the touch sensor laminate.
The method according to claim 1, Peel strength of the point adhesive layer to the touch sensor layer is 5 to 10 N / 25mm, touch sensor laminate.
The method according to claim 1, The lower structure comprises a lower substrate and a lower point adhesive layer formed between the lower substrate and the touch sensor layer, the touch sensor stack.
The touch sensor laminate according to claim 5, wherein the lower substrate includes a flexible display panel.
The method according to claim 1, The optical layer comprises a coated polarizer or a polarizing plate, a touch sensor laminate.
The touch sensor stack according to claim 1, wherein a central surface corresponding to 1/2 of the total thickness of the touch sensor stack is included in the touch sensor layer.
Flexible display panel;

A touch sensor layer stacked on the flexible display panel;

A point adhesive layer laminated on the touch sensor layer and having a Young's Modulus of 0.05 to 1 MPa; And

It includes an optical layer laminated on the point adhesive layer,

An image display apparatus having a thickness ratio of 12 to 23% represented by the following Equation 1:

[Equation 1]

|A-B|*100/B (%)

(In formula 1, A is the height from the upper surface of the optical layer to the interface of the touch sensor layer and the point adhesive layer, B is 1/2 of the total thickness of the image display device).
The image display device of claim 9, further comprising a window substrate stacked on the optical layer.
The image display device according to claim 9, wherein the thickness ratio is 17.7 to 21%, and the Young's modulus of the point adhesive layer is 0.05 to 0.25 MPa.