JP2023152248A - Optical stack and organic light emitting diode display employing the same - Google Patents

Abstract

To provide an optical stack and an organic light emitting diode display comprising the optical stack.SOLUTION: An optical stack has an adhesive layer. The adhesive layer is placed between a cover plate and a circular polarizer component, between the circular polarizer component and a touch component, or between the touch component and a display component. The storage modulus of the adhesive layer at 60°C ranges from 15 kPa to 30 kPa, and the ratio of the storage modulus at -30°C to the storage modulus at 60°C of the adhesive layer is between 6 and 16.SELECTED DRAWING: Figure 1

Description

The present invention relates to a flexible optical laminate and an organic light emitting diode display equipped with the same, and more particularly to an ultra-thin optical laminate having stable flexibility and an organic light emitting diode display equipped with the same.

Currently, circular polarizers (CPOLs) are often formed by combining a phase retardation layer (retarder) and a linear polarizer. In the field of displays, display devices usually include electrical signal processing elements (e.g., touch-sensing electrodes) and optical elements (e.g., optical films such as polarizing films, retardation films, etc.) to meet the end user's application requirements. When assembled, the electrical signal processing element and the optical element are bonded to each other via an optically transparent adhesive. However, in recent years, the usage environment, storage environment, and/or manufacturing environment of display devices has become harsher, and the application to flexible display devices has become full-scale, so it is necessary to consider the coordination of the characteristics of each film layer in the display device. There is. In particular, in order to apply the display device in a flexible manner, the above-mentioned optically transparent adhesive plays an important role. For example, an optically transparent adhesive may absorb stress when the display device is bent in order to avoid failure of the electrical signal processing element or optical element.

Patent Document 1 discloses a flexible display device in which a photoelectric element part and a touch function part are combined using a first adhesive film, and a touch function part and a window film are combined using a second adhesive film. .

Taiwan Patent No. I590119

Patent Document 1 discloses an adhesive film for a flexible display device and discusses the storage modulus of the adhesive film. For example, the analysis results show that in the temperature range from -20°C to 80°C, the average slope of the storage modulus of the adhesive film is -9.9 to 0, and the storage modulus of the adhesive film at 80°C is 10 kPa to 1000 kPa. Show that something is true. However, in WO 2006/011001, only a tensile test is performed, which cannot effectively verify the state of the adhesive film in the bent/folded state. That is, US Pat. No. 5,030,000 fails to provide an adhesive suitable for bendable/flexible/wrapable products, especially at low temperatures (eg, about -30°C to about -20°C). Therefore, there is an urgent need to find a preferred specification standard suitable for both high-temperature and low-temperature environments (for example, from about -30° C. to about 60° C.).

Therefore, the present invention has been made in view of the above-mentioned shortcomings.

One of the objects of the present invention is to provide a flexible optical laminate that includes at least one adhesive layer and is formed by integrating an electrical signal processing element and an optical element. By providing an adhesive layer, these two components with different properties/functions can be used in coordination without sacrificing their respective properties. Additionally, the present invention allows products to be made thinner to meet integration requirements, thereby enabling foldable ultra-thin optical stacks and products containing the same.

Another object of the present invention is that the storage modulus of the adhesive layer at 60°C is in the range of 15 kPa to 30 kPa, and the ratio of the storage modulus of the adhesive layer at -30°C to the storage modulus of the adhesive layer at 60°C is 6. To provide a flexible optical laminate in the range of . Thereby, it is possible to realize an adhesive layer that can maintain viscoelasticity over a wide temperature range and has excellent returnability from a bent state to a normal/non-bent state.

The flexible optical laminate according to the present invention includes at least one adhesive disposed between the cover plate and the circular polarizer component, between the circular polarizer component and the touch component, or between the touch component and the display component. Contains layers. The storage modulus of the adhesive layer at 60°C is in the range of 15 kPa to 30 kPa, and the ratio of the storage modulus of the adhesive layer at -30°C to the storage modulus at 60°C is in the range of 6 to 16.

In one embodiment of the present invention, in the optical laminate according to the present invention, the storage modulus of the adhesive layer at 60°C is 27 kPa, and the storage modulus of the adhesive layer at -30°C is higher than the storage modulus of the adhesive layer at 60°C. The ratio is 6.6.

In one embodiment of the present invention, in the optical laminate of the present invention, the storage modulus of the adhesive layer at 60°C is 17 kPa, and the storage modulus of the adhesive layer at -30°C is greater than the storage modulus of the adhesive layer at 60°C. The ratio is 15.8.

In one embodiment of the present invention, in the optical laminate of the present invention, the storage modulus of the adhesive layer at 60°C is 28 kPa, and the storage modulus of the adhesive layer at -30°C is greater than the storage modulus of the adhesive layer at 60°C. The ratio is 13.3.

In one embodiment of the present invention, in the optical laminate according to the present invention, the glass transition temperature of the adhesive layer is lower than -30°C.

In one embodiment of the present invention, in the optical laminate according to the present invention, the adhesive layer is made of a material containing a hydroxyl group-containing acrylic polymer.

In one embodiment of the present invention, the optical laminate according to the present invention has an interfacial adhesion force between the adhesive layer and the circular polarizer component of greater than 500 g/inch in a temperature range of -30°C to 60°C.

Furthermore, the present invention provides an organic light emitting diode display with stable flexibility to which the optical laminate is applied. The organic light emitting diode display consists of a cover plate, a circular polarizer, a touch component, a display component, a first adhesive layer disposed between the cover plate and the circular polarizer component, and a first adhesive layer between the circular polarizer component and the touch component. a second adhesive layer disposed between the touch component and the display component; and a third adhesive layer disposed between the touch component and the display component. A cover plate is placed on top of the organic light emitting diode display. The storage moduli at 60° C. of the first, second, and third adhesive layers are each independently in the range of 15 kPa to 30 kPa. The ratio of the storage modulus at −30° C. to the storage modulus at 60° C. of the first, second, and third adhesive layers is each independently in the range of 6 to 16.

The flexible optical laminate of the present invention has at least one adhesive layer and is formed by integrating an electrical signal processing element and an optical element. By providing an adhesive layer, these two components with different properties/functions can be used in coordination without sacrificing their respective properties. Furthermore, the present invention allows products to be made thinner to meet integration requirements, thereby making it possible to realize foldable ultra-thin optical laminates and products including the same. In addition, the storage modulus of the adhesive layer at 60°C is in the range of 15 kPa to 30 kPa, and the ratio of the storage modulus at -30°C to the storage modulus of the adhesive layer at 60°C is in the range of 6 to 16. . Thereby, the adhesive layer can ensure a good balance between cohesive force and adhesive force. Therefore, it is possible to realize an adhesive layer that maintains viscoelasticity in a wide temperature range and has excellent recovery properties, and excellent reliability and durability can be obtained.

To assist those skilled in the art in understanding the objects, features, and advantages of the present invention, the following specific embodiments and accompanying drawings are provided that describe the present invention in detail.

The invention will become apparent to those skilled in the art from reading the following detailed description of preferred embodiments thereof, taken in conjunction with the accompanying drawings.

FIG. 1 is a schematic diagram illustrating an exemplary optical stack according to the present invention. FIG. 2 is an exemplary schematic diagram showing an optical laminate under peel strength testing. FIG. 3 is an exemplary schematic diagram showing an optical laminate under bending test.

BRIEF DESCRIPTION OF THE DRAWINGS Advantages, features, and techniques of the invention will become apparent from the following detailed description of exemplary embodiments of the invention, taken in conjunction with the accompanying drawings. However, the present invention is not limited to the following embodiments, and can be implemented in various ways.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms "a" and "the" include the plural forms unless the context clearly dictates otherwise.

Additionally, it is to be understood that when an element is placed "on" another element, that element may be placed directly on top of another element, or there may be intervening elements. Furthermore, the thickness values referred to herein are not fixed values, and those skilled in the art can appreciate that manufacturing tolerances, measurement errors, etc. may exist therein. Preferably, there may be a margin of error of 10%, 20% in the thicknesses described herein.

Also, although terms such as "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. should be understood. These terms are only used to distinguish the respective elements. Accordingly, a first element in some embodiments may be referred to as a second element in other embodiments without departing from the teachings of the present invention. In this specification, the same elements are given the same reference numerals. Additionally, terms such as "plate," "layer," "film," or other similar terms are used interchangeably herein to refer to optical elements and are not otherwise indicated herein. Unless otherwise specified, they are only literally different from each other.

FIG. 1 shows an exemplary optical stack 100 according to the present invention. Flexible optical laminate 100 includes at least one adhesive layer 11. Adhesive layer 11 may be placed between substrates 12 and 13. In the present invention, the substrates 12 and 13 may be cover plates, circular polarizer components, touch components, display components, or any other. For example, the adhesive layer 11 may be placed between the cover plate (ie, the substrate 13), which becomes the touch surface of the mobile device, and the circular polarizer component (ie, the substrate 12). Alternatively, in another embodiment, adhesive layer 11 may be placed between the circular polarizer component (ie, substrate 13) and the touch sensitive component (ie, substrate 12). Alternatively, in another embodiment, adhesive layer 11 may be placed between the touch sensitive component (ie, substrate 13) and the display component (ie, substrate 12). The above description is for illustrative purposes only and is not intended to limit the invention. Due to the properties of the adhesive layer 11 according to the present invention, the bendable ultra-thin integrated touch module and products containing the touch module can be manufactured over a wide operating temperature range (temperature range from about -30°C to about 60°C). etc.), it can be realized by two or more layers of components.

Specifically, according to some embodiments, adhesive layer 11 may be an optically clear adhesive (OCA), which includes a hydroxyl-containing acrylic polymer. It may be made of any material. Specifically, in some embodiments, the adhesive layer 11 includes an alkyl (meth)acrylate monomer, a monomer containing ethylene oxide, a monomer containing propylene oxide, a monomer containing an amino group, a monomer containing an amide group, or an alkoxy group. , a monomer containing a phosphoric acid group, a monomer containing a sulfonic acid group, a monomer containing a phenyl group, and a monomer containing a silanyl group. More specifically, the glass transition temperature of the adhesive layer 11 may be −30° C. or lower.

Additionally, in some embodiments of the present disclosure, the circular polarizer component may be an antireflection optical element consisting of a combination of at least one phase retardation layer and at least one linear polarizing layer. In order to achieve the above-mentioned objectives of integration and product thinning, in one embodiment of the present invention, the phase retardation layer is a 1/4 wavelength phase compensation layer (1/4 wavelength retardation plate, or 1/4 wavelength retardation plate). It can be selected from 45 μm thick cyclic olefin polymer (COP) which can be used as a quarter wave plate (QWP). Further, in some embodiments of the present disclosure, the linearly polarizing layer may be, but is not limited to, a commonly commercially available polarizer having a degree of polarization (DOP) of greater than 98%. A linear polarizing layer is a combination (hereinafter referred to as an A-type polarizing layer) in which a polyvinyl alcohol (PVA) material is fixed between two protective films (such as triacetate cellulose (TAC)). It's okay. Alternatively, the linear polarizing layer may be a polyvinyl alcohol (PVA) material (hereinafter referred to as B-type polarizing layer) with a single-sided protective coating (such as TAC). The above two types of polarizing layers or any polarizing layer in other forms/stack are suitable for the present invention, which is not limited to the embodiments. In one embodiment of the present invention, the phase retardation layer includes a quarter-wave phase compensation layer and a half-wave phase compensation layer (also referred to as a half-wave retarder or half-wave plate (HWP)). It may be a combination of (called). In one embodiment of the invention, the phase retardation layer may be a 1/2 wavelength phase compensation layer. In an embodiment of the present invention, the characteristics of an optical film will be explained using a retardation value (ie, in-plane retardance/retardation (R ₀ )) measured in a plane perpendicular to the thickness direction of the object to be measured. In an embodiment of the present invention, a commercially available device having the model number AxoScan (available from Axometrics Inc.) is used to measure the in-plane retardation value of the object under test within the wavelength range of visible light.

Since the present invention relates to the storage modulus of the adhesive layer 11, a method for measuring it will be explained. The storage modulus can be measured by performing a dynamic load test/dynamic mechanical analysis (DMA) on the adhesive layer 11. Its basic principle is to apply periodic stress with a certain frequency to the adhesive layer 11, analyze the strain magnitude and phase difference between the applied dynamic force and the deformation of the adhesive layer 11, and thereby This includes obtaining dynamic properties of the material such as stiffness (i.e. storage modulus) and damping (i.e. loss coefficient). The dynamic stress waveform may be a sine wave, a triangular wave, a square wave, etc. to simulate the stress mode of the material under real working conditions. For example, when stress is applied to a material, the ratio of stress and strain is a complex coefficient, and the phase difference between them can be defined as a phase angle δ that represents the degree of delay in deformation of the material. The complex coefficient is in complex coordinates, the angle between the complex coefficient and the x-axis is the phase angle δ, the storage modulus and the loss modulus are the projections of the complex coefficient onto the real axis and the imaginary axis, and tan δ is It is defined as a loss coefficient representing the loss characteristics of the adhesive layer 11.

Since the present invention relates to the peel strength (also called interfacial adhesive strength) between the adhesive layer 11 and the various components/substrates mentioned above, a method for measuring the peel strength will be explained. FIG. 2 is an exemplary schematic diagram showing an optical laminate under peel strength testing. First, an adhesive composition to be tested is applied onto a leader tape 22 made of a polyethylene terephthalate (PET) film, and after the adhesive composition is cured, a first adhesive film 21 is formed. The first adhesive film 21 and the leader tape 22 are combined to form an adhesive sheet 200. Here, the thickness of the leader tape 22 is 50 μm. The sample 23 is then adhered to the other side of the first adhesive film 21 to form an adhesive interface. The sample 23 may be any one selected from a cover plate, a circular polarizer component, a touch component, a display component, and the like. The user can replace the specimen 23 to be tested with different parts depending on the requirements. Furthermore, the sample 23 can be fixed onto the glass 25 via the second adhesive film 24. Finally, one side of the adhesive sheet 200 is bent 180 degrees to the opposite side, a tensile force is applied under different temperature environments, and the adhesive sheet 200 is pulled at a speed of 300 mm/min. Thereby, the peel strength of the adhesive interface formed between the test adhesive composition and sample 23 is measured under different temperature environments. Note that since the first adhesive film 21 and the second adhesive film 24 are formed of the same adhesive composition, it is difficult to determine whether interfacial peeling occurs between the first adhesive film 21 and the sample 23. Regardless of whether interfacial peeling occurs between sample 23 and second adhesive film 24, the measured peel strength can be considered as the peel strength between the test adhesive composition and sample 23.

Since the present invention relates to a bending test of the adhesive layer 11 using different substrates, the measuring method will be described later. As used herein, the term "passing a bending test" means that the test subject proceeds to the next step without exhibiting any failure behavior. FIG. 3 is an exemplary schematic diagram showing an optical laminate under bending test. The bending test in the present invention is mainly performed on the test optical laminate (as shown in FIG. 3), and its main purpose is to bend the test optical laminate used to simulate an actual touch display device. The purpose is to confirm whether or not you will pass the exam. Therefore, when conducting a bending test, the main purpose is to evaluate the bendability of the test optical laminate using different optical adhesive materials under different temperature environments, and the structure of each layer will be discussed later. do. The bending test method involves performing a bending test on the optical laminate for testing at least 200,000 times under different temperature environments to determine whether the optical laminate for testing exhibits failure behavior such as destruction, buckling, or peeling. If it is confirmed that no failure behavior has occurred in the optical laminate for testing, it is determined that the bending test has been passed.

Hereinafter, an example of the touch display device 1 according to the present invention will be described with reference to FIG. 3. The touch display device 1 includes a cover plate 131, a first adhesive layer 111, a circular polarizer component having a linear polarizer 132 and a 1/2 wavelength retardation plate 133, a second adhesive layer 112, and a 1/4 wavelength retardation plate 133. A touch component 121 having a wavelength retarder 135 and touch-sensitive electrodes 134 and 136 disposed on the top and bottom surfaces of the quarter-wave retarder 135, a third adhesive layer 113, and a display portion 122 is provided. Note that in consideration of test costs, a layer of transparent polyimide film (CPI: Colorless PI) with a thickness of 50 μm is used as the display section 122 instead of an actual organic light emitting diode display (OLED). .

The cover plate 131 can be used as the outermost component of the touch display device 1 and can also be defined as a user-accessible component. The cover plate 131 may be a single layer of inorganic packaging material, a multilayer laminate of inorganic packaging materials, or a laminate of pairs of inorganic and organic packaging materials. Inorganic mounting materials used include, for example, silicon nitride (SiN _x ), silicon oxide (SiO _x ), silicon oxynitride (SiON _x ), aluminum oxide (AlO _x ), titanium oxide (TiO _x ), glass, or resin. layers, etc., but is not limited thereto. In this embodiment, the cover plate 131 is a transparent polyimide film (CPI: Colorless PI) with a thickness of 50 μm.

A circular polarizer component essentially comprises a linear polarizer and a phase retarder, which is often used as an anti-reflection sheet, which has the function of solving the problem of reflected light due to incident light from the external environment. The problem of reflected light degrades display performance. The phase retarder used may be a quarter wave plate (QWP) or a half wave plate (HWP). In theory, when externally incident light passes through the outermost linear polarizer, the linear polarizer converts the incident light into linearly polarized incident light. The polarization direction of the linearly polarized incident light and the direction of the linear polarizer are perpendicular. This linearly polarized incident light then enters a quarter-wave plate used as a phase retarder, a phase difference is generated in the linearly polarized incident light, and the linearly polarized incident light is converted into counterclockwise circularly polarized light. Next, after being reflected by the display panel, the light is converted into clockwise circularly polarized light in the opposite direction and passes through a quarter-wave plate used as a phase retarder. Finally, since the polarization direction of the linearly polarized incident light from the display panel is orthogonal to the polarization direction of the linearly polarized incident light from the external environment, the incident light from the display panel cannot pass through the linear polarizer. It is not visible to the human eye and provides an anti-reflection function. In other words, an antireflection optical element can be configured by a combination of the linear polarizer 132 and the 1/2 wavelength retardation plate 133 according to this embodiment. Here, the linear polarizer 132 is coupled to the cover plate 131 via the first adhesive layer 111, and the 1/2 wavelength retardation plate 133 is coupled to the touch component 121 via the second adhesive layer 112. be combined. More specifically, the 1/2 wavelength retardation plate 133 is a liquid crystal type retardation layer that can be a single layer liquid crystal coating. The retardation value R ₀ (550) at 550 nm of the liquid crystal type retardation layer is in the range of 230 nm to 310 nm, preferably at least 250 nm. In this embodiment, the 1/2 wavelength retardation plate 133 is made of a commercially available "Reactive Mesogen (RM)" reactive liquid crystal having a thickness of about 2 μm, a slow axis of about 15 degrees, and a retardation value of 260 nm at 550 nm. However, it is not limited to this. The linear polarizer 132 is the above-mentioned B-type polarizing layer, which is a commercially available product SPN32-1805M manufactured by SAPO. A type 1/2 wavelength retardation plate 133 is attached.

The touch component 121 of the present invention includes indium tin oxide (ITO), metal mesh, silver nanowires (SNW), carbon nanotubes (CNT), graphene, and poly(3,4-ethylene). Transparent conductive materials, such as conductive polymers such as dioxythiophene (PEDOT), can be used to form touch-sensing electrodes on a substrate through a patterning process. In the embodiment shown in FIG. 3, touch component 121 includes a quarter-wave retarder 135 and touch-sensitive electrodes 134 and 136 disposed on the top and bottom surfaces of quarter-wave retarder 135. In the embodiment shown in FIG. In other words, the quarter-wave retarder 135 can be used as a carrier substrate/support substrate for the touch-sensing electrodes 134 and 136, and the retardation value R ₀ (550 nm) of the quarter-wave retarder 135 at 550 nm ) may be in the range 100 nm to 160 nm, preferably at least 130 nm. Specifically, in this embodiment, the quarter wavelength retarder 135 is made of a cyclic olefin copolymer (COP) material (manufactured by Konica Minolta) with a thickness of 25 μm and a retardation value of 131 nm at 550 nm. In this embodiment, the touch component 121 is made of silver nanowires, and the method may be to coat the top and bottom surfaces of the quarter-wave retarder 135 with a dispersion containing silver nanowires. For example, silver nanowires are dispersed in a solvent such as water, alcohol, ketone, ether, hydrocarbon or aromatic solvent (benzene, toluene, xylene, etc.) to form a coating material/slurry. In addition, the above coating material/slurry includes carboxymethyl cellulose (CMC), 2-hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC), sulfonic acid ester, sulfuric ester, disulfonate, It may contain additives, surfactants, or binders such as sulfosuccinates, phosphates, or fluorine-containing surfactants. After coating is completed, a curing process forms a layer of silver nanowires. This silver nanowire layer may then be used to form touch-sensing electrodes 134 and 136 by patterning methods well known in the art, such as photolithography processes using photoresists or etching processes. I can do it.

In one embodiment, the silver nanowires are non-sloughingly formed on the surface of the polymer phase retardation layer, thereby forming a conductive layer of silver nanowires. Silver nanowires can contact each other to provide a continuous current path, thereby forming a conductive network. In other words, the silver nanowires are in contact with each other at their intersections, thereby forming a path for electron transfer. That is, one silver nanowire and another silver nanowire come into direct contact at their intersection, forming a low-resistance electron transfer path. In one embodiment, if the sheet resistance in the area or structure is higher than 10 ⁸ ohms/square, then the sheet resistance is 10 ⁴ ohms/square, 3000 ohms/square, 1000 ohms/square, 350 ohms/square, or 100 ohms. In situations higher than /square, it can be considered electrical insulation. In one embodiment, the sheet resistance of the silver nanowire layer with silver nanowires is less than 100 ohms/square. Silver nanowire electrodes have high transmittance, for example, about 88%, 90%, 91%, 92%, 93%, or more in the wavelength range of visible light.

In one embodiment, the polymer layer may be further arranged such that the polymer layer covers the silver nanowires. In certain embodiments, a suitable polymer is coated onto the silver nanowires, and the polymer in a fluid state with flow properties can be infiltrated between the silver nanowires as a filler. Silver nanowires are embedded in the polymer, thereby forming a composite structure after the polymer is cured. In short, this step adds a polymer layer onto the silver nanowires by coating the polymer onto the silver nanowires, while embedding the silver nanowires within the polymer layer to form a composite structure. In some embodiments of the invention, the polymer layer is formed from an insulating material. For example, the material of the polymer layer may be a non-conductive resin or other organic material such as polyacrylate, epoxy resin, polyurethane, polysilane, silicone, poly(silicon-acrylic acid), polyethylene (PE), polypropylene (PP). : polypropylene), polyvinyl butyral (PVB), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), and the like. In some embodiments of the invention, polymer layers may be formed by methods such as spin coating, spray coating, and printing. In some embodiments, the polymer layer has a thickness of about 20 nm to 10 mm, 50 nm to 200 nm, or 30 nm to 100 nm. For example, the thickness of the polymer layer can be about 90 nm or 100 nm. The above specific methods may refer to references such as US Patent Application Publication No. 2019/0227650, China Patent Application Publication No. 101292362, the entire context of which is herein incorporated by reference. can be incorporated. Silver nanowire slurry and polymer coating material are both available from Cambrios.

Table 1 shows the storage modulus of adhesive layers 111, 112 and 113 made of adhesive materials of Comparative Examples 1 and 2, as well as the adhesive layers 111, 112 and 113 applied at different temperatures, shown in FIG. The results of the bending test of the structure are shown. Storage modulus is measured by performing a dynamic load test. As shown in Table 1, the storage modulus at 60°C of the adhesive materials of Comparative Examples 1 and 2 exceeds 30 kPa, and the storage modulus at -30°C of the adhesive materials of Comparative Examples 1 and 2 at 60°C is The ratio of elastic moduli is greater than 16. That is, the storage modulus of the adhesive material of Comparative Example 1 at -30°C is 4000 kPa, the storage modulus of the adhesive material of Comparative Example 1 at 60°C is 100 kPa, and the storage modulus of the adhesive material of Comparative Example 1 at -30°C is 100 kPa. The ratio of the storage modulus at -30°C to that at 60°C is 40. Furthermore, the storage modulus of the adhesive of Comparative Example 2 at -30°C is 3800 kPa, the storage modulus of the adhesive of Comparative Example 2 at 60°C is 40 kPa, and the storage modulus of the adhesive of Comparative Example 2 at 60°C is 3800 kPa. The ratio of storage modulus at −30° C. to elastic modulus is 95.

From the storage modulus of the adhesive layers of Comparative Examples 1 and 2 at high temperatures (for example, about 60° C.), it can be seen that the storage moduli of the adhesive materials of Comparative Examples 1 and 2 at high temperatures are excessively high. An excessively high storage modulus means that the adhesive is relatively hard and its viscosity is reduced. Therefore, in the high-temperature bending test, the above-mentioned sample peeling/blistering phenomenon occurs, and the flexibility requirements of the product cannot be met. When the temperature changes significantly, optical laminates tend to become brittle under hot and cold conditions due to significant changes in storage modulus, causing instability. According to Comparative Examples 1 and 2, when the storage modulus of the adhesive material changes significantly, for example, in Comparative Example 1, the ratio between the storage modulus at about -30°C and the storage modulus at about 60°C becomes 40, Under low-temperature conditions (for example, from about -30°C to about -20°C), the adhesive material cannot deform according to bending, and therefore may break due to stress concentration, resulting in damage to the optical laminate 100. It can be seen that there is a risk of mechanical damage and optical distortion (unevenness). Therefore, according to the bending test results of Comparative Examples 1 and 2 of the present invention, in order to meet the flexibility requirements of products (for example, display touch products simulated in Figure 3) under high and low temperature conditions, , it is considered necessary to find an appropriate range of the storage modulus of the adhesive material at 60°C, and an appropriate range of the ratio of the storage modulus at -30°C to the storage modulus at 60°C. From the results of the bending tests of Comparative Examples 1 and 2, the storage modulus of the adhesive at 60° C. is preferably less than 40 kPa in order to meet the requirements. From the results of the bending tests of Comparative Examples 1 and 2, the ratio of the storage modulus at -30°C to the storage modulus at 60°C is preferably less than 40 in order to meet the requirements.

Table 2 shows the peel strength of adhesives according to Comparative Examples 1 and 2 measured at different interfaces. As shown in Table 2, the peel strength at −20° C. of the adhesives according to Comparative Examples 1 and 2 is less than 500 g/inch. More specifically, in Comparative Example 1, the peel strength at -20°C of the adhesive layer 11 with respect to the optical element 13 (polarizing layer and phase retardation layer) and the electrical signal processing element 12 (touch component) was 175 g/1, respectively. inch, 127 g/inch and 124 g/inch. In addition, in Comparative Example 2, the peel strength at -20°C of the adhesive layer 11 with respect to the optical element 13 (polarizing layer and retardation layer) and the electrical signal processing element 12 (touch component) was 122 g/inch and 349 g/inch, respectively. inch, only 241g/inch. Under low temperature conditions, the adhesive layer 11 according to Comparative Examples 1 and 2 cannot deform in response to bending, which causes stress concentration and affects the adhesive strength of the adhesive layer 11, making it unreliable for a long time. It is clear that a consistent adhesion cannot be maintained. Such peel strength data can explain why the adhesives according to Comparative Examples 1 and 2 do not pass the above bending test at low temperatures. According to the peel strength of Comparative Examples 1 and 2, in order to meet the requirements, the adhesive layer 11 for the optical element 13 (polarizing layer and phase retardation layer) and the electrical signal processing element 12 (touch component) was Preferably, the peel strength is greater than 349 g/inch.

Table 3 shows the storage modulus of adhesive layers 111, 112, and 113 made of the adhesive materials of Examples 1 to 3 of the present invention, and Figure 3 when adhesive layers 111, 112, and 113 were applied at different temperatures. The results of the bending test of the structure shown in are shown below. Storage modulus is measured by performing a dynamic load test. As shown in Table 3, the storage modulus at 60°C of the adhesives of Examples 1 to 3 of the present invention is in the range of 15 kPa to 30 kPa, and the storage modulus of the adhesives of Examples 1 to 3 at 60°C is in the range of 15 kPa to 30 kPa. The ratio of the storage modulus at −30° C. to that at −30° C. ranges from 6 to 16. Specifically, at a temperature of -30° C., the storage modulus of the adhesive of Example 1 is 270 kPa, so Example 1 passes the bending test. At a temperature of 60° C., the storage modulus of the adhesive of Example 1 is 17 kPa, so Example 1 passes the bending test. The ratio of the storage modulus at -30°C and the storage modulus at 60°C of the adhesive of Example 1 is 15.8. Also, at a temperature of -30° C., the storage modulus of the adhesive of Example 2 is 371 kPa, so Example 2 passes the bending test. At a temperature of 60° C., the storage modulus of the adhesive of Example 2 is 28 kPa, so Example 2 passes the bending test. The ratio of the storage modulus at -30°C and the storage modulus at 60°C of the adhesive of Example 2 is 13.3. Furthermore, at a temperature of -30° C., the storage modulus of the adhesive of Example 3 is 177 kPa, so Example 3 passes the bending test. At a temperature of 60° C., the storage modulus of the adhesive of Example 3 is 27 kPa, so Example 3 passes the bending test. The ratio of the storage modulus at -30°C and the storage modulus at 60°C of the adhesive of Example 3 is 6.6.

According to the ratio of the storage modulus of the adhesive materials of Examples 1 to 3 under the test conditions, the storage modulus of the adhesive materials of Examples 1 to 3 increases with the temperature change under the test conditions. It is clear that there is no change. In terms of stability, the adhesive layer 11 of Examples 1 to 3 can maintain viscoelasticity over a wide temperature range and also has good recovery potential and achieves excellent stability. be able to. When the ratio of G'(-30°C)/G'(60°C) is greater than 16, the storage modulus of the adhesive at -30°C becomes excessively high, the adhesive becomes relatively hard, and the viscosity decreases. . On the other hand, in the present invention, it is considered that the lower the ratio of G'(-30°C)/G'(60°C), the better. Although the low storage modulus of the adhesive at -30°C helps the product to bend, in reality, an excessively low storage modulus also means that the cohesiveness of the molecules inside the adhesive and the degree of polymerization of the molecules are also very low. means. As a result, the strength of the adhesive becomes excessively low, which is disadvantageous in processing. That is, excessively low material strength is disadvantageous to the actual manufacturing process. Patent Document 1 discloses the average gradient of storage modulus from -20°C to 80°C and the storage modulus at each temperature, but does not disclose the storage modulus at -30°C, and the present invention does not disclose the storage modulus at -30°C. , the analysis is performed using interpolation/extrapolation, which is commonly used in general experimental research. The ratio G'(-30°C)/G'(60°C) for the nine specific examples disclosed in US Pat. Therefore, according to the above explanation, the adhesive has the disadvantage of having an excessively low material strength, which is disadvantageous to the process of Patent Document 1.

In addition, Comparative Example 1 did not pass the bending test at 60°C, and it was determined that the storage modulus of the adhesive layer at 60°C was not greater than 40 kPa. Further, according to Examples 1 to 3, if the storage modulus of the adhesive layer at 60° C. is less than 30 kPa, a sufficiently low storage modulus can be ensured even in a high temperature environment. It was found that the optical laminate 100 of No. 3 was able to pass the bending test under high temperature conditions and was able to achieve highly reliable adhesion over a long period of time even under high temperature environments. Note that a low storage modulus allows the adhesive to deform in response to bending, preventing the risk of rupture or damage; however, if the storage modulus is too low, the adhesive will be difficult to process, handle, and retain its shape. It is not possible to maintain the cohesive strength required for adhesives, etc., making the adhesive manufacturing process difficult. Therefore, when the data of Examples 1 to 3 are combined, the present invention provides a balance between the cohesive strength and adhesive strength of the adhesive when the storage modulus of the adhesive at 60° C. is in the range of 15 kPa to 30 kPa. and can provide preferred adhesive specifications.

Table 4 shows the peel strength of the adhesive layer 11 according to Examples 1 to 3 of the invention, measured at different temperatures and at different interfaces. As shown in Table 4, the peel strength at -20° C. of the adhesives according to Examples 1 to 3 of the present invention is 500 g/inch or more at all interfaces. More specifically, in Example 1, the peel strength at -20°C of the adhesive for the optical element 13 (polarizing layer and phase retardation layer) and the electrical signal processing element 12 (touch component) was 2812 g/inch, respectively. , 2132 g/in, and 1531 g/in, and other data can be interpreted accordingly. According to the bending tests previously described and the peel strengths shown in Table 4, within the temperature range used, the adhesive exhibits excellent reliability and peel strength even when the peel strength between the adhesive and other interfaces exceeds 500 g/in. It is clear that it maintains its durability. According to the peel strength of Examples 1 to 3, the peel strength at -20°C of the adhesive layer 11 with respect to the optical element 13 (polarizing layer and phase retardation layer) and the electrical signal processing element 12 (touch component) meets the requirements. In order to meet this requirement, it is preferably greater than 1400 g/inch and more preferably greater than 1453 g/inch. According to the peel strength of Examples 1 to 3, the peel strength at 60°C of the adhesive layer 11 with respect to the optical element 13 (polarizing layer and phase retardation layer) and the electrical signal processing element 12 (touch component) satisfies the requirements. Therefore, it is preferably greater than 500 g/inch, and more preferably greater than 528 g/inch.

It can be appreciated that those skilled in the art can make various modifications and adjustments based on the above embodiments, which are not listed one by one here. In the following, we will focus on the application of the organic light emitting diode display with stable flexibility according to the present embodiment, so that those skilled in the art can understand the possible variations more clearly. Elements with the same reference numerals as in the above embodiment are substantially the same as those described using FIGS. 1 to 3. Note that the same elements, features, and advantages as those of the optical laminate 100 described above will not be repeatedly described.

In addition, in this embodiment, the thickness of the first adhesive layer 111, the second adhesive layer 112, and the third adhesive layer 113 may be in the range of 25 μm to 50 μm. In addition, when the thickness of the adhesive film is 25 μm to 50 μm, the first adhesive layer 111, the second adhesive layer 112, and the third adhesive layer 113 have a haze of 5% or less, especially It may contain up to 3%, in particular up to 1%, of adhesive film. When the adhesive layer 11 within these ranges is used for display, excellent transparency is achieved, but the present invention is not limited thereto.

In this embodiment, the first adhesive layer 111, the second adhesive layer 112, and the third adhesive layer 113 may be formed of the same material. In the present invention, "the same material" means that its constituent elements and physical properties are the same. In other embodiments, first adhesive layer 111, second adhesive layer 112, and third adhesive layer 113 may be formed from different materials. In another embodiment, the thickness of the second adhesive layer 112 may be greater than the thickness of each of the first adhesive layer 111 and the third adhesive layer 113. Therefore, the second adhesive layer 112 can reach a higher adhesive strength than the first adhesive layer 111 and the third adhesive layer 113. Therefore, by adjusting the thickness of the adhesive layer 11, it is possible to improve the reliability of the organic light emitting diode display while obtaining effects such as flattening the optical element.

Finally, the technical features of the present invention and its achieved technical effects are summarized below.

First, in the optical laminate 100 of the present invention, the storage modulus of the adhesive at 60°C is in the range of 15 kPa to 30 kPa, and the ratio of the storage modulus of the adhesive at -30°C to the storage modulus of the adhesive at 60°C is 6. The range is from 16 to 16. As a result, a good balance between the cohesive strength and adhesive strength of the adhesive layer 11 can be maintained, and the optical laminate and its products can meet actual usage requirements.

The peel strength of the adhesive of the optical laminate 100 according to the present invention is then greater than 500 g/inch at different interfaces at the temperatures used. Therefore, it is clear that the adhesive layer 11 according to the present invention maintains excellent reliability and durability even in harsh usage, storage, and/or manufacturing environments and meets the actual usage requirements.

Although the implementation of the present invention has been described above with reference to the above-described specific embodiments, those skilled in the art can easily understand the technical features, advantages, and effects of the present invention from this disclosure.

The above description is only a preferred embodiment of the present invention and does not limit the scope of the present invention. Other equivalent changes and modifications made without departing from the spirit of the invention are to be included within the scope of the appended claims.

Claims (8)

at least one adhesive layer disposed between the cover plate and the circular polarizer component, between the circular polarizer component and the touch component, or between the touch component and the display component;
The storage modulus of the adhesive layer at 60° C. is in the range of 15 kPa to 30 kPa, and the ratio of the storage modulus at -30° C. to the storage modulus at 60° C. of the adhesive layer is in the range of 6 to 16. Optical laminate. The adhesive layer has a storage modulus of 27 kPa at 60°C, and a ratio of the storage modulus at -30°C to the storage modulus at 60°C of the adhesive layer is 6.6. The storage modulus at 60°C of the adhesive layer is 17 kPa, and the ratio of the storage modulus at -30°C to the storage modulus at 60°C of the adhesive layer is 15.8, or 60 kPa of the adhesive layer. The optical laminate according to claim 1, wherein the storage modulus at -30°C of the adhesive layer is 28 kPa, and the ratio of the storage modulus at -30°C to the storage modulus at 60°C of the adhesive layer is 13.3. The optical laminate according to claim 1 or 2, wherein the adhesive layer has a glass transition temperature of less than -30°C. The optical laminate according to claim 1 or 2, wherein the adhesive layer is made of a material containing a hydroxyl-containing acrylic polymer. The optical laminate of claim 1 or 2, wherein the interfacial adhesion between the adhesive layer and the circular polarizer component is greater than 500 g/inch within a temperature range of -30°C to 60°C. An organic light emitting diode display,
cover plate,
circular polarizer,
touch parts,
display parts,
a first adhesive layer disposed between the cover plate and the circular polarizer;
a second adhesive layer disposed between the circular polarizer and the touch component; and a third adhesive layer disposed between the touch component and the display component;
the cover plate is disposed on the top layer of the organic light emitting diode display;
The storage modulus at 60° C. of at least one of the first, second and third adhesive layers is in the range of 15 kPa to 30 kPa,
An organic light emitting diode display, wherein the ratio of the storage modulus at -30°C to the storage modulus at 60°C of at least one of the first, second and third adhesive layers ranges from 6 to 16. At least one of the first, second and third adhesive layers has a storage modulus of 27 kPa at 60°C, and at least one of the first, second and third adhesive layers has a storage modulus at 60°C. The ratio of the storage modulus at -30° C. to the storage modulus is 6.6, the storage modulus at 60° C. of at least one of the first, second and third adhesive layers is 17 kPa, and the the ratio of the storage modulus at -30°C to the storage modulus at 60°C of at least one of the first, second and third adhesive layers is 15.8; The storage modulus at 60°C of at least one of the adhesive layers is 28 kPa, and the storage modulus at -30°C with respect to the storage modulus at 60°C of at least one of the first, second and third adhesive layers. 7. The organic light emitting diode display according to claim 6, wherein the ratio of the ratio is 13.3. An organic light emitting diode display according to claim 6 or 7, wherein the glass transition temperature of at least one of the first, second and third adhesive layers is less than -30°C.

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