WO2014027761A1

WO2014027761A1 - Flexible substrate for display element, method for manufacturing same, and display device using same

Info

Publication number: WO2014027761A1
Application number: PCT/KR2013/006394
Authority: WO
Inventors: 김태호; 곽병도; 김영권; 김태정; 이상걸; 이우진; 임성한; 정은환; 최석원; 김성국
Original assignee: 제일모직 주식회사
Priority date: 2012-08-17
Filing date: 2013-07-17
Publication date: 2014-02-20
Also published as: KR101669317B1; KR20140024216A

Abstract

A flexible substrate for a display element of the present invention comprises: a matrix; a reinforcing member impregnated in the matrix; and a buffer layer formed on at least one side of the matrix, wherein during a mandrel bend test, a diameter of a bar having a crack is 7mm or less.

Description

Flexible substrate for display device, manufacturing method thereof and display device using same

The present invention relates to a flexible substrate for a display device, a method of manufacturing the same, and a display device using the same.

BACKGROUND ART As a liquid crystal display device or a substrate for an organic EL display device, a color filter substrate, or a solar cell substrate, glass having excellent heat resistance and transparency and low coefficient of linear expansion has been used. Recently, as miniaturization, thinning, weight reduction, impact resistance, and flexibility are demanded as substrate materials for display devices, particularly flexible display substrates, plastic substrates have been in the spotlight as materials for replacing glass substrates. .

As the plastic substrate, materials such as polyester (polyethylene terephthalate) or polyethylene naphthalate (PEN), polycarbonate, polyether sulfone, cyclic olefin resin, epoxy resin or acrylic resin are used. However, these materials have a high coefficient of thermal expansion, which may cause problems such as warpage of the product and disconnection of wiring. In addition, although a technique of applying a resin having a low coefficient of thermal expansion, such as polyamide-based resin, has been developed as a substrate, polyamide-based resin is not suitable as a substrate material due to its very low transparency and high birefringence and hygroscopicity.

To solve this problem, a silicone fiber reinforced plastic (FRP) composite sheet having low thermal expansion and providing flexibility, heat resistance and transparency by using a low anisotropic silicone rubber (rubber) as a matrix with glass fiber cloth was developed. There is a bar. However, in order to use such a composite sheet as a substrate for a display, an inorganic membrane barrier layer for preventing moisture permeability required for manufacturing a substrate and preventing gas passage to the outside of the composite sheet should be secured. However, such an inorganic membrane barrier layer has a high elastic modulus, different mechanical properties from the resin matrix, and a weak interfacial adhesion between the two layers, which may cause cracks, warpage, and the like. And durability can be reduced. In addition, the silicon fiber reinforced plastic (FRP) composite sheet has a high surface roughness, which makes it difficult to be used as a flexible substrate for a liquid crystal display device or an organic EL display device.

As disclosed in Japanese Laid-Open Patent Publication No. 2009-012288, in the substrate for a display device using an existing composite sheet, in order to improve surface roughness, the surface roughness is applied to both sides of the core layer by applying a core resin or a heterogeneous liquid crude liquid used for manufacturing the composite sheet. Is improving. However, in order to improve the surface roughness by applying a resin or a liquid crude liquid, the viscosity, the thickness of the coating film, the physical properties of the liquid crude liquid and the like have to be controlled.

In addition, the silicon FRP composite sheet may cause deformation of the entire substrate due to heat or the like when the planarization layer is applied.

Therefore, there is a need for the development of a high heat resistance, high flatness buffer layer for a silicon FRP composite sheet to ensure stable physical properties when additional coating the barrier layer and the like on the silicon FRP composite sheet.

An object of the present invention is to provide a flexible substrate for a display device with improved surface roughness and a method of manufacturing the same.

Another object of the present invention is to provide a flexible substrate for a display device having excellent moisture permeability, low thermal expansion coefficient, flexibility and durability, and a method of manufacturing the same.

Still another object of the present invention is to provide a flexible substrate for a display device and a method of manufacturing the same, which do not generate cracks and have excellent flatness without controlling the viscosity, the thickness of the coating film, the physical properties of the liquid crude liquid, and the like.

One aspect of the present invention relates to a flexible substrate for a display element. The display substrate flexible substrate may include a matrix; Reinforcing material impregnated in the matrix; And a buffer layer formed on at least one surface of the matrix, wherein a rod having a crack during the Mandrel Bend Test has a diameter of 7 mm or less.

The flexible substrate for the display device may have an elastic modulus of 100 MPa or more.

The flexible substrate for the display device may have an elastic modulus of 1 GPa or more.

The matrix may comprise a silicone rubber.

In the flexible substrate for the display device, a gas barrier layer may be further formed on the buffer layer.

The surface roughness Ra of the flexible substrate for the display device may be 40 nm or less.

The buffer layer may have a thickness of 0.01 to 50 μm.

The buffer layer may include at least one of (meth) acrylic resin, polyimide resin, polyester resin, polycarbonate resin, epoxy resin, and urethane resin.

The reinforcing material is one of glass fiber, glass fiber cloth, glass fabric, glass nonwoven fabric, glass mesh, glass beads, glass flake, silica particles, and colloidal silica. It may contain the above.

The gas barrier layer may include at least one of silicon nitride, silicon oxide, silicon oxynitride, silicon carbide, aluminum nitride, aluminum oxide, tantalum oxide, titanium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO).

The gas barrier layer may have an elastic modulus of about 10 to about 500 GPa at 25 ° C.

The flexible substrate for the display device may have a moisture permeability of about 0.15 g / m ² / day or less, for example, 0.10 g / m ² / day or less.

Another aspect of the present invention relates to a method for manufacturing a flexible substrate for a display device. The method is a method of manufacturing a flexible substrate for a display device, which comprises forming a laminated sheet by laminating a buffer layer on at least one surface of a matrix including a silicon-based rubber impregnated with a reinforcing material, and the display device flexible substrate is a Mandrel Bend Test. The diameter of the rod where the crack occurs may be 7 mm or less.

The laminated sheet, the reinforcing material on one surface of the buffer layer; And it is characterized in that it comprises a step of coating and curing the resin for forming the matrix on the reinforcing material.

In one embodiment, the laminated sheet is formed by applying a matrix forming resin to a reinforcing material to form a matrix impregnated with the reinforcing material; And applying and curing a resin for forming a buffer layer on at least one surface of the matrix impregnated with the reinforcing material.

In another embodiment, the laminate sheet has a reinforcing material on one side of the first buffer layer; Applying a matrix forming resin to the reinforcing material to form a matrix; And laminating the second buffer layer on the matrix to cure the same.

In another embodiment, the method may further include forming a gas barrier layer on the buffer layer.

Another aspect of the invention relates to a display device. The display device includes a substrate; An organic light emitting device formed on the substrate; And an encapsulation member encapsulating the organic light emitting device, and the substrate may be a flexible substrate for a display device.

The present invention provides a display device having improved surface roughness, excellent moisture permeability, low coefficient of thermal expansion, flexibility and durability, no cracking, and excellent flatness without controlling the viscosity, thickness of the coating film, or physical properties of the liquid crude liquid. It is to provide a flexible substrate and a method of manufacturing the same.

1 is a schematic cross-sectional view of a flexible substrate for a display device according to an exemplary embodiment of the present invention.

2 is a schematic cross-sectional view of a flexible substrate for a display device according to another exemplary embodiment of the present invention.

3 is a schematic cross-sectional view of a display device according to an embodiment of the present invention.

4 is a cross-sectional view of a portion of a display device according to another embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, it will be described embodiments of the present application in more detail. However, the technology disclosed in the present application is not limited to the embodiments described herein and may be embodied in other forms. It is merely to be understood that the embodiments introduced herein are provided so that the disclosure can be made thorough and complete, and that the spirit of the present application can be fully conveyed to those skilled in the art. In the drawings, the width, thickness, and the like of the components are enlarged in order to clearly express the components of each device. In addition, although only a part of the components are shown for convenience of description, those skilled in the art will be able to easily understand the rest of the components. When described in the drawings as a whole, when an observer pointed out and an element is referred to as being placed on top of another element, this means that one element may be placed directly on top of another element or additional elements may be interposed between them. Include. In addition, one of ordinary skill in the art may implement the spirit of the present application in various other forms without departing from the technical spirit of the present application.

1 is a schematic cross-sectional view of a flexible substrate for a display device according to an exemplary embodiment of the present invention. As shown in FIG. 1, the flexible substrate 100 for a display device of the present invention includes a matrix 10; Reinforcing material (15) impregnated in the matrix (10); And

buffer layers

21 and 22 formed on at least one surface of the matrix 10.

2 is a schematic cross-sectional view of a flexible substrate for a display device according to another exemplary embodiment of the present invention. As shown in FIG. 2, the flexible substrate 200 for a display device of the present invention includes a matrix 10; Reinforcing material (15) impregnated in the matrix (10); And

buffer layers

21 and 22 formed on at least one surface of the matrix 10. And

gas barrier layers

31 and 32 formed on the

buffer layers

21 and 22.

As the matrix 10 used in the present invention, a matrix having excellent high temperature processability, flexibility, and the like may be used. For example, a matrix including a silicone rubber, a matrix including an acrylic resin, a matrix including an epoxy resin, and a urethane type A matrix containing a resin can be used, and for example, a matrix containing the silicone rubber can be used. In embodiments, the matrix may be a matrix having an elastic modulus of about 0.01 to about 20 MPa, for example, about 1 to about 15 MPa at 25 ° C. In the elastic modulus range, the flexible substrate for the display device may have excellent flexibility, heat resistance, moisture permeability, durability, and flatness. In addition, the glass transition temperature of the matrix 10 may be about -150 to about 30 ℃, for example, about -40 to about 10 ℃. It is excellent in flexibility and rigidity in the above range and has a small coefficient of thermal expansion.

In embodiments, a matrix comprising a silicone rubber may be applied to maintain a low coefficient of thermal expansion. In the present invention, the elastic modulus of the matrix and the buffer layer is measured at 25 ° C. using an MTS Alliance RT / 5 test frame based on a 100N load cell. Specifically, the specimens were weighted with two air grips spaced 25 mm apart and pulled at a crosshead speed of 1 mm / min. This is obtained by continuously collecting load and displacement data and taking the maximum slope of the initial part of the load displacement curve as a Young's modulus.

As the matrix forming resin capable of forming the matrix, a resin for forming a matrix may be used, and for example, may include silicone rubber, acrylic resin, epoxy resin, urethane resin, and the like. Silicone-based rubber may be included. As the silicone rubber, an organopolysiloxane having an average degree of polymerization of about 5 to about 2,000 may be used. Examples of the organopolysiloxanes include polydimethylsiloxane, polymethylphenylsiloxane, polyalkylarylsiloxane, polyalkylalkylsiloxane, and the like. These are three-dimensional molecules of the network structure. In embodiments, the number of the net bond points is about 5 to about 500 may have a structure containing one per R ₂ SiO. Organopolysiloxanes having a viscosity of about 5 to about 500,000 Cst at 25 ° C. may be used. Within this range, the composite sheet may have excellent flexibility, heat resistance, moisture permeability, durability and flatness. The viscosity of the silicone rubber can be, for example, from about 5 to about 120,000 Cst, in embodiments from about 100 to about 100,000 Cst, in embodiments from about 1,000 to about 80,000 Cst at 25 ° C.

In another embodiment, the matrix together with the silicone rubber is styrene-butadiene rubber (SBR), butadiene rubber, isoprene rubber, chloroprene rubber, neoprene rubber, ethylene-propylene-diene terpolymer, styrene-ethylene-butylene- Styrene (SEBS) block copolymer, Styrene-ethylene-propylene-styrene (SEPS) block copolymer, Acrylonitrile-butadiene rubber (NBR), hydrogenated nitrile rubber (NBR), Flori It may further comprise one or more selected from the group consisting of fluorinated rubber, and plasticized polyvinylchloride rubber.

The reinforcing material 15 used in the present invention may be impregnated in the matrix 10 and exist inside the matrix to impart heat resistance stability to the

substrates

100 and 200. Although not shown in the drawings, the reinforcement 15 may be dispersed in the matrix 10 or may be impregnated in a woven form, or may be impregnated with the matrix 10 arranged in a uni-direction. In addition, the reinforcing material 15 may be formed of a single layer or a plurality of layers.

The reinforcing material 15 is glass fiber, glass fiber cloth (glass fiber cloth), glass fabric (glass fabric), glass nonwoven fabric, glass mesh (glass mesh), glass beads, glass flake (glass flake), silica particles, colloidal silica And the like can be used. These may be used alone or in combination of two or more thereof.

The reinforcing material 15 may have a refractive index difference of about 0.01 or less from the matrix 10. Within this range, it may have excellent transparency and light transmittance. In embodiments, the refractive index difference from the matrix 10 may be about 0.0001 to about 0.007.

In the present invention, after the resin constituting the matrix 10 is impregnated with the reinforcing material 15, it can be produced in the form of a sheet by crosslinking or curing the resin.

The thickness of the matrix 10 impregnated with the reinforcing material 15 may be about 10 to about 200 μm, for example, about 50 to about 100 μm. Handling can be easy in the above range.

The buffer layers 21 and 22 used in the present invention may be formed on at least one surface of the matrix 10. In FIG. 1, the buffer layers 21 and 22 are formed on both surfaces of the matrix 10, but may be formed only on one surface thereof. The buffer layers 21, 22 may have an elastic modulus of greater than about 100 MPa at 25 ° C., for example, greater than 100 MPa and less than or equal to about 10 GPa. When the elastic modulus of the buffer layers 21 and 22 is in the above range, the crack characteristics are excellent. When the elastic modulus of the buffer layers 21 and 22 is in the above range, the matrix 10 and the gas barrier layers 31 and 32 are less than about 100 MPa or more than about 10 GPa. Due to the difference in physical properties such as elastic modulus of the, there is a fear that cracks, warpage and the like. In addition, the glass transition temperature of the buffer layers 21 and 22 may be about 30 to about 400 ℃. If the glass transition temperature is less than about 30 ° C., the heat resistance may be inferior when the gas barrier layers 31 and 32 are formed, and thermal deformation may occur in the entire substrate, and the glass transition temperature may exceed about 400 ° C. In this case, there is a fear that the surface roughness may not be improved. The elastic modulus at 25 ° C. of the buffer layers 21, 22 may be, for example, about 500 MPa to about 7 GPa, in particular about 1 to about 5 GPa. The glass transition temperatures of the buffer layers 21 and 22 may be, for example, about 50 to about 350 ° C, and in some embodiments, about 150 to about 300 ° C.

In embodiments, the buffer layers 21 and 22 may have a surface roughness Ra of about 100 nm or less, for example, about 10 nm or less, and in embodiments, about 0.001 to about 5 nm. It is possible to improve the surface roughness in the above range and can be applied to a flexible substrate for a display device.

The buffer layers 21 and 22 may have a thickness of about 0.01 to about 50 μm, for example, about 1 to about 30 μm. In the above range can be expressed without improving the surface roughness without inhibiting the intrinsic properties of the matrix.

The buffer layers 21 and 22 may include (meth) acrylic resins, polyimide resins, polyester resins, and resins such as polycarbonate resins, epoxy resins, urethane resins, and the like, or two or more of them. It can be applied in combination. In addition, the buffer layers 21 and 22 may be formed using a film made of the resin, or a film formed by applying and curing the resin composition on the matrix 10.

The gas barrier layers 31 and 32 of the present invention may be formed on the buffer layers 21 and 22. In FIG. 2, the gas barrier layers 31 and 32 are formed on both surfaces of the buffer layers 21 and 22, but the present invention is not limited thereto. The gas barrier layers 31 and 32 may be formed only on one surface of the buffer layers 21 and 22. The gas barrier layers 31 and 32 may be formed of a material used for a flexible substrate for a conventional display device. For example, silicon nitride, silicon oxide, silicon oxynitride, silicon carbide, aluminum nitride, aluminum oxide, tantalum oxide, Titanium oxide, ITO (Indium Tin Oxide) and IZO (Indium Zinc Oxide) may include one or more. The gas barrier layer may form a single layer or two or more kinds of barrier layers may be stacked to form a plurality of layers.

The gas barrier layers 31 and 32 may have an elastic modulus of about 10 to about 500 GPa, for example, about 15 to about 350 GPa at 25 ° C. In the above range, the flexible substrate for the display device may have excellent flexibility, moisture permeability, mechanical properties, and durability, and at the same time, lower flatness and moisture permeability.

The thickness of the gas barrier layers 31 and 32 may be about 0.01 μm to about 1.0 μm, but is not limited thereto.

The

flexible substrates

100 and 200 for display devices of the present invention may have a moisture permeability of about 0.01 to about 0.15 g / m ² / day, for example, about 0.05 to about 0.10 g / m ² / day. In addition, the

flexible substrates

100 and 200 for the display device may have a thermal expansion coefficient of about 1 to about 6 ppm / ° C, for example, about 2 to about 5 ppm / ° C. The display substrate

flexible substrates

100 and 200 may have a surface roughness of about 40 nm or less, for example, about 0.01 to about 35 nm, in some embodiments, about 0.1 to about 30 nm, and in other embodiments, about 0.1 to about 10 nm. nm can be achieved.

In addition, the

flexible substrates

100 and 200 for the display element may be cracked when the cracks are evaluated by the Mandrel Bend Test using respective rods having a diameter of 5 to 20 mm according to ASTM D522-93a. The rod may have a diameter of about 7 mm or less, for example about 5 to about 6 mm.

The

flexible substrates

100 and 200 for the display device may have an elastic modulus of about 100 MPa or more, for example about 1 GPa or more, and in some embodiments, about 1.2 to 10 Gpa at 25 ° C. The elastic modulus of the substrate is a value obtained by applying pressure with a force of 1000 mN using Fischer MH500 Micro indentation equipment.

Another aspect of the present invention relates to a method of manufacturing a flexible substrate for a display element.

According to one or more exemplary embodiments, a method of manufacturing the flexible substrate 100 for a display device may include stacking buffer layers 21 and 22 on at least one surface of a matrix 10 including the silicon-based rubber impregnated with a reinforcing material 15. Forming a step.

According to another embodiment of the present invention, a method of manufacturing the flexible substrate 200 for the display device may include buffer layers 21 and 22 stacked on at least one surface of the matrix 10 including the silicon-based rubber impregnated with the reinforcing material 15 and the buffer layer ( Forming a laminated sheet by forming gas barrier layers 31 and 32 on the

substrates

21 and 22.

As described above, the buffer layers 21 and 22 may have an elastic modulus of greater than about 100 MPa and less than or equal to about 10 GPa and a glass transition temperature of about 30 to about 400 degrees Celsius at 25 ° C. The manufactured flexible substrate for the display device may have a diameter of about 7 mm or less, in which a crack occurs in a mandrel bend test.

In one embodiment, the laminated sheet, the reinforcing material 15 is placed on one surface of the

buffer layer

21 or 22 having a film form, and the matrix forming resin is applied to the reinforcing material 15 and cured. It can be prepared by forming a.

When the buffer layers 21 and 22 are formed on both surfaces of the matrix 10 in which the reinforcing material 15 is impregnated, it will be described below. First, the reinforcing material 15 is placed on one surface of the first buffer layer 21, and the matrix forming resin is applied to the reinforcing material 15 to form the matrix 10. As such, when the second buffer layer 22 is laminated after the matrix 10 is formed, as shown in FIG. 1, the matrix 10 to the second impregnated with the reinforcing material 15 and the second buffer layer 22 are shown in FIG. 1. A laminate sheet in which the buffer layers 22 are sequentially stacked is formed. In this case, as described above, the first and second buffer layers 21 and 22 have an elastic modulus of about 100 MPa to about 10 GPa and a glass transition temperature of about 30 to about 400 ° C. at 25 ° C. do. The laminated sheet is cured by heat or ultraviolet rays as it is, and forms gas barrier layers 31 and 32 on the first and second buffer layers 21 and 22, respectively. The gas barrier layers 31 and 32 may be physically deposited, chemically deposited, coated, sputtered, evaporated, ion plated, wet coated, or organic inorganic multilayer coating on the surfaces of the buffer layers 21 and 22. It can be formed as.

In another embodiment, the laminated sheet is formed by applying a matrix forming resin to the reinforcing material (15) to form a matrix (10) impregnated with the reinforcing material (15); (Meth) acrylic resins, polyimide resins, polyester resins and resins for buffer layer formation such as polycarbonate, epoxy, urethane, etc. are applied to at least one surface of the matrix 10 impregnated with the reinforcing material 15 and cured. It can be produced by forming the buffer layer (21, 22).

Next, gas barrier layers 31 and 32 may be formed on the buffer layers 21 and 22. The gas barrier layers 31 and 32 may be physically deposited, chemically deposited, coated, sputtered, evaporated, ion plated, wet coated, or organic inorganic multilayer coating on the surfaces of the buffer layers 21 and 22. It can be formed as.

Another aspect of the invention relates to a display device including the flexible substrate. Specific examples of the display device may include a liquid crystal display device, an organic light emitting diode display device, a touch panel, and the like, but are not limited thereto. The flexible substrate of the present invention may be applied to the substrate of the display device.

In one embodiment, the display device includes a substrate and an organic light emitting element formed on the substrate. 3 is a cross-sectional view of a display device according to an embodiment of the present invention. As shown in FIG. 3, the display apparatus includes a substrate 100 and an organic light emitting diode formed on the substrate 100, and the organic light emitting diode includes a first electrode 111 and the first electrode 111. ) And a second electrode 113 formed on the light emitting layer 112. The organic light emitting diode may be encapsulated by the encapsulation member 114. The emission layer 112 includes an organic compound that may emit light when voltage is applied from the first and

second electrodes

111 and 113. The flexible substrate of the present invention may be applied to the substrate 100.

4 is a cross-sectional view of a portion of an OLED display device according to another embodiment of the invention. As shown in FIG. 4, the display apparatus includes a substrate 300, a protective film 120 formed under the substrate 300, a buffer layer 25 formed on the substrate 300, and an upper portion of the buffer layer 25. The gate insulating layer 40 may be formed between the gate electrode 41, the gate electrode 41, and the buffer layer 25. An active layer 135 including source and drain

regions

131 and 133 is formed in the gate insulating layer 40. The passivation layer 61 including the contact hole 62 is formed on the interlayer insulating layer 51, and the interlayer insulating layer 51 on which the source and drain

electrodes

52 and 53 are formed is formed on the gate insulating layer 40. The first electrode 70 and the pixel defining layer 80 are formed. The organic emission layer 71 and the second electrode 72 are formed on the pixel defining layer 80. Here, the substrate 300 may be a flexible substrate according to embodiments of the present invention, and the buffer layer 25 may be replaced with a buffer layer included in the flexible substrate according to embodiments of the present invention as needed.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, the following examples are provided to help the understanding of the present invention, and the scope of the present invention is not limited to the following examples. Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.

실시예Example

Specifications of the specific components used in the following Examples and Comparative Examples are as follows.

(a) Matrix: Silicone rubber (polydimethylsiloxane (PDMS), product name: Sylgard 184, manufacturer: Dow Corning) with an elastic modulus of 10 MPa and a glass transition temperature of -30 ° C was used.

(b) Reinforcing material: Glass fiber cloth (product name: 3313, manufacturer: Nittobo) was used.

(c) buffer layer

(c1) A polyimide film (product name: LaRC ™ -CP1 , manufacturer: ManTech) having an elastic modulus of 2 GPa, a glass transition temperature of 350 ° C., and a surface roughness of 6 nm was used.

(c2) A polycarbonate film (product name: Lexan, manufactured by Dupont teijin) having an elastic modulus of 2.0 to 2.4 GPa, a glass transition temperature of 150 ° C., and a surface roughness of 5 nm was used.

(c3) A polyethylene terephthalate film (product name: Skyrol ^, manufacturer: SKC) having an elastic modulus of 2.0 to 2.4 GPa, a glass transition temperature of 75 ° C., and a surface roughness of 6 nm was used.

(c4) An acrylic cured resin (product name: EA-HG011, manufacturer: Osaka Gas) having an elastic modulus of 4.0 to 4.5 GPa and a glass transition temperature of 200 ° C was used.

(c5) An acrylic cured resin (product name: OER09, manufacturer: Minutatec) having an elastic modulus of 2.0 to 2.5 GPa and a glass transition temperature of 100 ° C was used.

(c6) An acrylic curable resin (product name: CK, manufacturer: Noro pyo paint) having an elastic modulus of 1.0 to 1.5 GPa and a glass transition temperature of 50 ° C was used.

(c7) Silicone rubber (polydimethylsiloxane (PDMS), product name: Sylgard 184, manufactured by Dow Corning) and silica particles (product name: Aerosil, manufactured by Evonik) having an elastic modulus of 50 MPa and a glass transition temperature of -30 ° C. The composition which mixed Degussa company) was used.

(c8) Silicone rubber (polydimethylsiloxane (PDMS), product name: Sylgard 184, manufactured by Dow Corning) and silica particles (product name: Aerosil380, manufactured by Evonik) having an elastic modulus of 100 MPa and a glass transition temperature of -30 ° C. The composition which mixed Degussa company) was used.

(c9) A silicone rubber (polydimethylsiloxane (PDMS), product name: Sylgard 184, manufactured by Dow Corning) with an elastic modulus of 10 MPa and a glass transition temperature of -30 ° C was used.

(d) Gas barrier layer: Silicon oxide and silicon nitride were used.

The elastic modulus of the matrix or buffer layer is the value measured at 25 ° C. using an MTS Alliance RT / 5 test frame based on 100 N load cells, each of which is made into a film form. Specifically, the specimens were weighted with two air grips spaced 25 mm apart and pulled at a crosshead speed of 1 mm / min. Load and displacement data can be collected continuously and obtained by taking the maximum slope of the initial part of the load displacement curve as a Young's modulus.

실시예 1Example 1

A transparent imide film (c1) having a thickness of 10 µm was placed on a glass substrate, and a reinforcing material (b) was placed thereon, and then a matrix resin (a) was applied onto the reinforcing material. A 10 μm-thick transparent imide film (c1) was placed on the matrix resin, and a glass substrate was placed. Then, the matrix resin was impregnated with a reinforcing material through lamination. After thermal curing, the glass substrate was removed to prepare a laminated sheet having a thickness of 100 μm with a reinforcing material impregnated into the matrix.

실시예 2Example 2

The same procedure as in Example 1 was carried out except that a transparent imide film (c1) having a thickness of 30 μm was used instead of the transparent imide film having a thickness of 10 μm.

실시예 3Example 3

The same procedure as in Example 1 was carried out except that a polycarbonate film (c2) having a thickness of 30 μm was used instead of the transparent imide film having a thickness of 10 μm.

실시예 4Example 4

The same procedure as in Example 1 was performed except that a 30 μm-thick polyethylene terephthalate film (c3) was used instead of a 10 μm-thick transparent imide film.

실시예 5Example 5

A matrix resin (a) was applied on the reinforcing material (b) to prepare a matrix (silicon FRP) impregnated with a reinforcing material having a thickness of 90 μm. The laminated sheet having a thickness of 100 μm was prepared by applying and curing an acrylic curable resin (c4) to both surfaces of the matrix resin impregnated with the reinforcing material to form a buffer layer (c). A flexible substrate for a display device was manufactured by forming a gas barrier layer (d) having a thickness of 100 nm using alternating silicon oxide and silicon nitride by sputtering on the laminated sheet.

실시예 6Example 6

Except for using the acrylic curing resin (c5) instead of the acrylic curing resin (c4) was carried out in the same manner as in Example 5.

실시예 7Example 7

Except for using the acrylic curing resin (c6) instead of the acrylic curing resin (c4) was carried out in the same manner as in Example 5.

비교예 1Comparative Example 1

After placing the reinforcing material (b) on the glass substrate, a matrix resin (a) was applied on the reinforcing material. After placing the glass substrate on the matrix resin, the matrix resin was impregnated with the reinforcing material through lamination. After thermal curing, the glass substrate was removed to prepare a sheet having a thickness of 90 μm in which the matrix was impregnated with a reinforcing material. A flexible substrate for a display device was manufactured by forming a gas barrier layer (d) having a thickness of 100 nm by alternately using silicon oxide and silicon nitride by sputtering on the sheet.

비교예 2Comparative Example 2

After placing the reinforcing material (b) on the glass substrate, a matrix resin (a) was applied on the reinforcing material. After placing the glass substrate on the matrix resin, the matrix resin was impregnated with the reinforcing material through lamination. After thermal curing, the glass substrate was removed to prepare a sheet having a thickness of 90 μm in which the matrix was impregnated with a reinforcing material. Plasma treatment of the surface of the sheet was performed by coating a silicone rubber (c9) on both sides with a thickness of 5 μm and ultraviolet curing to form a buffer layer (c), thereby preparing a laminated sheet having a thickness of 100 μm. A flexible substrate for a display device was manufactured by forming a gas barrier layer (d) having a thickness of 100 nm using alternating silicon oxide and silicon nitride by sputtering on the laminated sheet.

비교예 3Comparative Example 3

The same procedure as in Comparative Example 2 was carried out except that the composition (c7) was used instead of the silicone rubber (c9).

비교예 4Comparative Example 4

The same procedure as in Comparative Example 2 was carried out except that the composition (c8) was used instead of the silicone rubber (c9).

Specific compositions of the flexible substrates for display devices manufactured in Examples and Comparative Examples are shown in Table 1 below.

Table 1

	Matrix resin	Buffer layer (thickness)	Barrier layer
Example 1	Silicone rubber (a)	Transparent imide (c1) (10 micrometers)	-
Example 2	Silicone rubber (a)	Transparent imide (c1) (30 μm)	-
Example 3	Silicone rubber (a)	PC (c2) (30 μm)	-
Example 4	Silicone rubber (a)	PET (c3) (30 μm)	-
Example 5	Silicone rubber (a)	Acrylic Curing Resin (c4) (5㎛)	SiO ₂ / SiN
Example 6	Silicone rubber (a)	Acrylic Curing Resin (c5) (5㎛)	SiO ₂ / SiN
Example 7	Silicone rubber (a)	Acrylic Curing Resin (c6) (5㎛)	SiO ₂ / SiN
Comparative Example 1	Silicone rubber (a)	-	SiO ₂ / SiN
Comparative Example 2	Silicone rubber (a)	Silicone rubber (c9) (5㎛)	SiO ₂ / SiN
Comparative Example 3	Silicone rubber (a)	Silicone rubber (c7) (5㎛)	SiO ₂ / SiN
Comparative Example 4	Silicone rubber (a)	Silicone rubber (c8) (5㎛)	SiO ₂ / SiN

The moisture permeability, thermal expansion coefficient, surface roughness, crack and peeling occurrence, and elastic modulus of the flexible substrates for the display device manufactured in Examples and Comparative Examples were measured and the results are shown in Table 2 below.

Property evaluation method

(1) Moisture permeability (unit: g / m ² / day): Measured using the ASTM F 1249 method using the MOCON equipment. The prepared specimens were cut to a size of 30 mm x 40 mm and then measured by inserting them into a jig having a central portion. Water vapor pressure at 25 ° C. was treated at 100% relative humidity.

(2) Thermal expansion coefficient (unit: ppm / ℃): It was measured using a TMA (Texas Instrument, Q40) equipment and using the ASTM E 831 method.

(3) Surface roughness (surface roughness, unit: nm): Flatness (Ra) was measured using an Optical Surface Profiler (ZYGO, 700s) equipment.

(4) Cracks and Exfoliation: Cracks were evaluated by Mandrel Bend Test using respective rods having a diameter of 5 to 20 mm according to ASTM D522-93a. At this time, the diameter of the rod when a crack occurred was measured. The presence or absence of peeling was evaluated as the number of peelings by removing 100 pieces of scratches on the surface horizontally (1 mm) × length (1 mm) and attaching and detaching the 3M tape.

(5) Elastic modulus: The modulus of the substrate was measured by applying a pressure of 1000 mN to the substrate prepared in Examples and Comparative Examples using Fischer MH500 Micro indentation equipment.

TABLE 2

	Permeability (g / m ² / day)	Thermal expansion coefficient (ppm / ℃)	Surface roughness (nm)	Crack generating rod diameter (mm)	Peeling occurrence (number)	Elastic Modulus (GPa)
Example 1	0.1	3 ~ 5	9	6	0	1.8
Example 2	0.08	3 ~ 5	5	6	0	2.0
Example 3	0.1	3 ~ 5	8	6	0	2.1
Example 4	0.1	3 ~ 5	9	6	0	2.1
Example 5	0.1	3 ~ 5	20	5	0	4.3
Example 6	0.1	3 ~ 5	22	6	0	2.0
Example 7	0.1	3 ~ 5	34	6	0	1.3
Comparative Example 1	2.5	3 ~ 5	520	11	100	0.01
Comparative Example 2	2.5	3 ~ 5	121	11	100	0.01
Comparative Example 3	2.4	3 ~ 5	118	8	100	0.05
Comparative Example 4	2.3	3 ~ 5	87	8	100	0.09

From the results of Table 2, Examples 1 to 7 in which the high heat resistance and high flatness buffer layer according to the present invention are applied to the silicon matrix (silicon FRP) are excellent in moisture permeability, low thermal expansion coefficient, and surface roughness, and crack and peeling phenomenon. It can be seen that this does not occur.

On the other hand, Comparative Example 1, which does not use the buffer layer, and Comparative Examples 2 to 4, which use the buffer layer whose elastic modulus and / or glass transition temperature is out of the range of the present invention, have a large surface roughness value, and crack and peeling phenomenon may occur to display devices. It can be seen that it is not suitable as a flexible substrate.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be manufactured in various forms, and a person of ordinary skill in the art to which the present invention pertains has the technical idea of the present invention. However, it will be understood that other specific forms may be practiced without changing the essential features. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Claims

matrix;

Reinforcing material impregnated in the matrix; And

A buffer layer formed on at least one surface of the matrix;

Flexible board for display device with crack diameter of 7mm or less during Mandrel Bend Test.
The flexible substrate for a display device of claim 1, wherein the flexible substrate for a display device has an elastic modulus of 100 MPa or more.
The flexible substrate for a display device of claim 1, wherein the flexible substrate for a display device has an elastic modulus of 1 GPa or more.
The flexible substrate of claim 1, wherein the matrix comprises silicon-based rubber.
The flexible substrate for a display device of claim 1, wherein the flexible substrate for a display device further includes a barrier layer formed on the buffer layer.
The flexible substrate for a display device of claim 1, wherein the flexible substrate for a display device has a surface roughness Ra of 40 nm or less.
The flexible substrate of claim 1, wherein the buffer layer has a thickness of 0.01 to 50 μm.
The display device of claim 1, wherein the buffer layer comprises at least one of (meth) acrylic resin, polyimide resin, polyester resin, polycarbonate resin, epoxy resin, and urethane resin. Flexible substrate.
The method of claim 1, wherein the reinforcing material is glass fiber, glass fiber cloth, glass fabric, glass nonwoven fabric, glass mesh, glass beads, glass flakes, silica particles and A flexible substrate for a display device comprising at least one of colloidal silica.
The gas barrier layer of claim 1, wherein the gas barrier layer is one of silicon nitride, silicon oxide, silicon oxynitride, silicon carbide, aluminum nitride, aluminum oxide, tantalum oxide, titanium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). A flexible substrate for display elements comprising the above.
The flexible substrate of claim 1, wherein the gas barrier layer has an elastic modulus of about 10 GPa to about 500 GPa at 25 ° C. 7.
The flexible substrate for a display device of claim 1, wherein the flexible substrate for a display device has a moisture permeability of about 0.1 g / m 2 / day or less.
A method of manufacturing a flexible substrate for a display device comprising forming a laminated sheet by laminating a buffer layer on at least one surface of a matrix containing a silicon-based rubber impregnated with a reinforcing material,

The flexible substrate for a display device is a flexible substrate manufacturing method for a display device, characterized in that the diameter of the rod generating cracks during the Mandrel Bend Test is 7 mm or less.
The method of claim 13, wherein the laminated sheet,

Placing a reinforcement on one side of the buffer layer; And

A method of manufacturing a flexible substrate for a display device, comprising the step of coating and curing the resin for forming a matrix on the reinforcing material.
The method of claim 13, wherein the laminated sheet,

Applying a matrix forming resin to the reinforcing material to form a matrix impregnated with the reinforcing material; And

A method of manufacturing a flexible substrate for a display device, comprising the step of applying and curing a resin for forming a buffer layer on at least one surface of the matrix impregnated with the reinforcing material.
The method of claim 13, wherein the laminated sheet

Placing a reinforcement on one side of the first buffer layer;

Applying a matrix forming resin to the reinforcing material to form a matrix;

And laminating and curing the second buffer layer on the matrix.
The method of claim 13, further comprising forming a gas barrier layer on the buffer layer.
Board; An organic light emitting device formed on the substrate; And an encapsulation member encapsulating the organic light emitting device, wherein the substrate is a flexible substrate for a display device according to any one of claims 1 to 12.