Films, light-transmitting laminates, cover films and multi-layer electronic equipment

Abstract

To provide a film and a light-transmissive laminate having excellent mechanical properties and also excellent optical properties such as refractive index, haze, or yellowness, their use as cover films, and multilayer electronic equipment comprising the same.SOLUTION: A film comprises an elastic layer. The elastic layer has a refractive index of 1.48-1.58. The low temperature damage index is a difference between tensile elasticity and tensile strength at a specific temperature. The elastic layer has the low temperature damage index of 1,300 MPa or less at -40°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Embodiments relate to films having excellent optical properties such as refractive index, haze, and yellowness as well as excellent mechanical properties, light-transmitting laminates, cover films, and multi-layer electronic devices including the same. [Background technology]

[0002] As display device shapes become more diverse and their required functions change, they are gradually evolving into thinner, more functional shapes with wider screens. Display shapes have also evolved from the conventional flat shape to curved shapes, and are now changing to foldable, bendable, flexible, etc. In other words, the recent display shapes are evolving into shapes that can be changed in shape, such as folding and bending, which is different from the previous shape that simply evolved in the direction of larger areas.

[0003] PET film, which boasts excellent mechanical properties, chemical resistance, and moisture barrier properties, is widely used as a protective film for display screens. Examples include polyester protective film (Korean Patent No. 10-1730854) with improved optical properties that can be used as a protective film for polarizing plates, and protective film (Korean Patent No. 10-1746170) that can be used as a protective film for touch panels. However, due to its high modulus, PET film may not meet the required properties for curved surfaces or bent parts, which can be one of the causes of film lifting in multi-layer display devices.

[0004] In addition, compared to the hard glass that has been used to protect the display modules of display devices installed in existing portable electronic devices, PET film has weaker shock absorption properties (the ability to protect internal devices such as display modules from external impacts), so there are limitations to its ability to provide sufficient protection.

[0005] The above-mentioned background art is technical information that the inventor possessed in order to derive embodiments of the present invention or that he acquired in the process, and is not necessarily publicly known art that was disclosed to the general public prior to the filing of this application. Summary of the Invention [Problem to be solved by the invention]

[0006] The purpose of the embodiments is to provide a film, a laminated film, a light-transmitting laminate, a cover film, etc., having excellent optical properties such as a suitable refractive index, low haze, high light transmittance, and low retardation.

[0007] Another object of the present invention is to provide a light-transmitting laminate or cover film that includes the film and has excellent optical properties, as well as relatively constant elastic properties over a wide temperature range and excellent mechanical properties, making it advantageous for use as a cover window for a multi-layer electronic device.

[0008] Another object of the present invention is to provide a use of the film as a cover window for a foldable display, a bendable display, a flexible display, or the like.

[0009] Another object of the present invention is to provide a multi-layer electronic device including the cover film, which has excellent optical properties such as a suitable refractive index, low haze, high light transmittance, and low retardation, does not cause separation between layers even when repeatedly bent or rolled, and is resistant to external impacts.

[0010] Another object of one embodiment is to provide a use of the above-described film as a cover film applied in a multi-layer electronic device. [Means for solving the problem]

[0011] To achieve the above object, one embodiment is a film including an elastic layer, wherein the elastic layer has a low-temperature damage index of 1,300 MPa or less at -40°C.

[0012] The cold damage index is the difference between the tensile modulus and the tensile strength at a particular temperature.

[0013] The elastic layer may have a tensile strength of 150 MPa or less at -40°C.

[0014] The elastic layer may have a tensile modulus of elasticity at -40°C of 2,000 MPa or less.

[0015] The elastic layer may have a tensile modulus of elasticity at -10°C of 3,000 MPa or less.

[0016] The elastic layer may have a storage modulus at -40°C of 2,300 MPa or less.

[0017] The elastic layer may have an elongation of 200% or more at -10°C.

[0018] The elastic layer may have a refractive index of 1.48 to 1.58.

[0019] The elastic layer may have an in-plane retardation Re of 300 nm or less.

[0020] The elastic layer may have a haze of 3% or less.

[0021] The elastic layer may have a light transmittance of 85% or more.

[0022] The roughness reference value is the larger value of Ra1, which is the value of the surface roughness Ra of one surface, and Ra2, which is the value of the surface roughness Ra of the other surface.

[0023] The elastic layer may have a roughness standard of 0.5 μm or less.

[0024] The elastic layer may contain an amide residue.

[0025] The elastic layer may contain a polymer resin containing an amide residue.

[0026] The elastic layer may contain a polymer resin containing 50% by weight or more of amide residues as repeating units.

[0027] The film may include the elastic layer and a hardening layer disposed on one side of the elastic layer.

[0028] The refractive index of the elastic layer may be smaller than the refractive index of the hardness layer.

[0029] The difference between the refractive index of the elastic layer and the refractive index of the hard layer may be 0.2 or less.

[0030] An adhesive layer may be further disposed on the other surface of the elastic layer or between the one surface of the elastic layer and the hardness layer.

[0031] The refractive index of the elastic layer may be smaller than the refractive index of the adhesive layer.

[0032] The difference in refractive index between the adhesive layer and the elastic layer may be 0.2 or less.

[0033] The difference in refractive index between the adhesive layer and the hardness layer may be 0.2 or less.

[0034] The hardness layer may include a polyimide film or a glass layer.

[0035] The film may have a total thickness of 3,000 μm or less.

[0036] According to another embodiment, a light-transmitting laminate includes the above-described film.

[0037] The light-transmitting laminate may further include a glass layer disposed on one side or the other side of the elastic layer.

[0038] The glass layer may be tempered glass having a thickness of 200 μm or less.

[0039] A cover film according to yet another embodiment includes the above-described film.

[0040] Yet another embodiment is the use of the above-described film as a cover film.

[0041] Yet another embodiment is the use of the above-described light-transmitting laminate as a cover film.

[0042] The cover film may further include a glass layer disposed on one side or the other side of the elastic layer.

[0043] The glass layer may be tempered glass having a thickness of 200 μm or less.

[0044] According to yet another embodiment, a multi-layer electronic device includes the film described above.

[0045] According to yet another embodiment, a multi-layer electronic device includes a light-emitting functional layer and a film, the light-emitting functional layer has a display area that emits or does not emit light according to an external signal, and the film is disposed on the top or back surface of the display area. The film may be any of the above-described films.

[0046] According to yet another embodiment, a multi-layer electronic device includes a light-emitting functional layer and a film. The light-emitting functional layer has a display area that emits or does not emit light according to an external signal. The film is disposed on one surface of the light-emitting functional layer and covers at least a portion of the display area. The film may be any of the above-described films. [Effects of the Invention]

[0047] The films, light-transmitting laminates, and manufacturing methods thereof according to the embodiments may provide films having excellent optical properties such as a suitable refractive index, low haze, high light transmittance, and low retardation, as well as excellent mechanical properties such as a substantially low change in storage modulus over a wide temperature range and excellent elastic recovery, and may also provide efficient manufacturing methods for such films.

[0048] By including the film, the cover film, multi-layer electronic equipment, etc. of the embodiment can have excellent optical properties such as a suitable refractive index, low haze, high light transmittance, and low retardation, and at the same time, can have excellent bending and rolling properties over a wide temperature range, excellent elastic recovery, and excellent damage suppression effect due to external impact. [Brief explanation of the drawings]

[0049] [Figure 1] 1A, 1B, and 1C are conceptual diagrams illustrating cross sections of films according to embodiments. [Figure 2] 1A, 1B, and 1C are conceptual diagrams illustrating cross sections of films according to embodiments. [Figure 3] FIG. 1 is a conceptual diagram illustrating a method for producing a film. [Figure 4] 1 is a cross-sectional view illustrating a multi-layer electronic device according to an embodiment; [Figure 5] 1A, 1B, and 1C are cross-sectional schematic diagrams illustrating the configuration of a multi-layer electronic device according to an embodiment. [Figure 6] 1 is a cross-sectional view illustrating a multi-layer electronic device according to an embodiment; BEST MODE FOR CARRYING OUT THE INVENTION

[0050] The present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily understand the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. The same reference numerals are used throughout the specification to refer to similar parts.

[0051] In this specification, when a certain configuration "includes" another configuration, this does not mean that it excludes the other configurations, and that it may further include the other configurations, unless otherwise specified.

[0052] In this specification, when a certain component is said to be "connected" to another component, this includes not only the case where the components are "directly connected" but also the case where the components are "connected via another component between them."

[0053] In this specification, the term "B is located on A" means that B is located on A in direct contact with A, or that B is located on A with another structure located therebetween, and is not to be interpreted as being limited to B being located in contact with the surface of A.

[0054] As used herein, the term "combinations thereof" contained in a Markush expression means a mixture or combination of one or more elements selected from the group of elements set forth in the Markush expression, and means including one or more elements selected from the group of elements.

[0055] In this specification, the expression "A and / or B" means "A, B, or A and B."

[0056] In this specification, terms such as "first", "second" or "A", "B" are used to distinguish identical terms from each other unless otherwise specified.

[0057] In this specification, unless otherwise specified, the singular expression is to be construed as including the singular or plural as the context requires.

[0058] In this specification, unless otherwise specified, the refractive index is presented as measured at a wavelength of 550 nm.

[0059] In this specification, unless otherwise specified, the in-plane retardation Re or the thickness direction retardation Rth is explained based on the result measured at a wavelength of 550 nm using a film sample having a thickness of 100 μm.

[0060] In this specification, the storage modulus is described based on the storage modulus (E') measured using a TA Instruments DMA Q800 model in accordance with ASTM D4065. The storage modulus (E') was measured in MPa in the temperature range (-40 to 80°C) at 1 Hz and 2°C / min in dynamic mechanical analysis (DMA) tension mode.

[0061] In this specification, room temperature is defined as approximately 20°C, and ordinary temperature is defined as approximately 25°C.

[0062] In this specification, the in-plane retardation (Re) is a parameter defined as the product (ΔNxy×d) of the anisotropy of the refractive index of two orthogonal axes in the plane of the film (ΔNxy=|Nx-Ny|) and the film thickness d (nm), and is a measure of optical isotropy or anisotropy.

[0063] In this specification, the thickness direction retardation (Rth) is a parameter defined as the average of the retardations obtained by multiplying ΔNxz (=|Nx-Nz|) and ΔNyz (=|Ny-Nz|), which are two birefringences when viewed from a cross section in the thickness direction of the film, by the thickness d of the film.

[0064] In this specification, the hard layer means a layer having a surface hardness of H or more.

[0065] In this specification, letters and / or numbers written together with the names of compounds represent abbreviations for the names of the compounds.

[0066] In this specification, the relative size, thickness, etc. of components shown in the drawings may be exaggerated for ease of explanation.

[0067] The embodiment will be described in more detail below.

[0068] The inventors of the present embodiment have confirmed that by manufacturing an elastic layer in the form of a film, it is possible to provide a film having excellent tensile properties at low temperatures as well as excellent optical properties such as high light transmittance, low haze, appropriate refractive index, retardation properties, and UV resistance. The present embodiment confirms that the film of the present embodiment has a relatively constant storage modulus over a wide temperature range, and therefore can provide relatively constant elastic properties in various temperature environments, and can provide a film having excellent optical properties and excellent mechanical properties from low to high temperatures.

[0069] 1(a), 1(b), and 1(c) are conceptual diagrams illustrating cross sections of a film according to an embodiment, and FIG. 2(a), 2(b), and 2(c) are conceptual diagrams illustrating cross sections of a film according to an embodiment, and FIG. 3 is a conceptual diagram illustrating a method for manufacturing the film. The elastic layer included in the film, the film, and the method for manufacturing the film will be described with reference to FIGS. 1 to 3.

[0070] To achieve this object, the film 190 according to one embodiment includes an elastic layer 100 .

[0071] Elastic layer The elastic layer 100 has excellent mechanical properties, particularly at low temperatures.

[0072] The low-temperature damage index (unit: MPa) is the difference (MPa) between the tensile modulus (MPa) and the tensile strength (MPa) measured at a low temperature (a specific temperature below 0°C).

[0073] The elastic layer 100 may have a -40°C low temperature damage index of 1,300 MPa or less, or 1,200 MPa or less. The elastic layer 100 may have a -40°C low temperature damage index of 300 MPa or more. An elastic layer having such properties can have excellent mechanical properties even at very low temperatures and can substantially prevent the occurrence of film cracking.

[0074] The elastic layer 100 may have a -10°C low temperature damage index of 1,300 MPa or less, or 1,200 MPa or less. The elastic layer 100 may have a -10°C low temperature damage index of 200 MPa or more. An elastic layer having such properties can have excellent mechanical properties even at low temperatures.

[0075] The elastic layer 100 may have a tensile modulus of 2,000 MPa or less, 1,500 MPa or less, or 1,000 MPa or less, or 500 MPa or more at −40° C. The elastic layer 100 may have a tensile modulus of 3,000 MPa or less, 1,400 MPa or less, 1,200 MPa or less, 700 MPa or less, or 500 MPa or less, or 350 MPa or more at −10° C.

[0076] If the tensile modulus of the elastic layer 100 is too high at low temperatures, cracks may easily occur when repeatedly bending at low temperatures or when subjected to external impact.

[0077] When the tensile modulus of the elastic layer 100 is as described above, the occurrence of cracking and damage due to external impact can be significantly reduced even when repeated bending is performed at low temperatures.

[0078] The elastic layer 100 has a difference in low-temperature tensile modulus TM expressed by the following formula 2: -40-20 The difference TM between the low-temperature tensile moduli may be 1000 MPa or less. -40-20 means the difference between the tensile modulus value at -40°C and the tensile modulus value at 20°C.

[0079] [Formula 2] JPEG0007825346000001.jpg657

[0080] In the formula 2, TM -40-20 is the low-temperature tensile modulus difference, TM n is the tensile modulus measured at n°C.

[0081] The elastic layer 100 is a TM -40-20 may be 700 MPa or less, or 500 MPa or less, or may be 1 MPa or more.

[0082] The elastic layer 100 is a TM -40-20 When the elastic layer has the above structure, the elastic characteristics of the elastic layer can be substantially well maintained in the range of low temperature to room temperature, and particularly, when the elastic layer is laminated with other layers, the occurrence of peeling, lifting, etc. can be substantially suppressed even at low temperatures.

[0083] The elastic layer 100 may have an elongation of 200% or more at -40°C. The elastic layer 100 may have an elongation of 200% or more at -10°C. The elastic layer 100 may have an elongation of 200% or more at 20°C. The upper limit of the elongation of the elastic layer at each temperature was not measured, but it is thought to be 400% or less.

[0084] When the elongation of the elastic layer 100 is as described above, the elastic layer 100 may have excellent ductility not only at room temperature or normal temperature but also at low temperatures. When the elastic layer is applied to a flexible display, the elastic layer may have excellent ability to undergo repeated bending without cracking not only at room temperature but also at low temperatures.

[0085] The elastic layer 100 may have a tensile strength of 10 MPa or more, or 20 MPa or more, at -40°C. The elastic layer 100 may have a tensile strength of 200 MPa or less, or 150 MPa or less, at -40°C. The elastic layer 100 may have a tensile strength of 5 MPa or more, or 10 MPa or more, at -10°C. The elastic layer 100 may have a tensile strength of 400 MPa or less, or 150 MPa or less, at -10°C. The elastic layer 100 may have a tensile strength of 5 MPa or more, or 10 MPa or more, at 20°C. The elastic layer 100 may have a tensile strength of 300 MPa or less, or 150 MPa or less, at 20°C. An elastic layer 100 having these characteristics may have a tensile strength above a certain level over a wide temperature range, and have appropriate mechanical properties over a wide temperature range suitable for use as a cover film for a display.

[0086] The elastic layer 100 can have excellent optical properties.

[0087] The elastic layer 100 may have a refractive index of 1.48 to 1.58, or 1.50 to 1.55. The elastic layer may have a refractive index of 1.505 to 1.53. When an elastic layer having such a refractive index is used as a protective layer for a display device, it is advantageous for realizing a clearer display.

[0088] The elastic layer 100 may have a haze of 3% or less, or 2% or less. The elastic layer 100 may have a haze of 1.5% or less, or 1.2% or less. The elastic layer 100 may have a haze of 0.01% or more, or 0.1% or more. When the elastic layer has such a haze, it is suitable for application to the display area of ​​a display device.

[0089] The elastic layer 100 may have a visible light transmittance of 85% or more, 88% or more, or 90% or more. The elastic layer may have a visible light transmittance of 99.99% or less. The elastic layer 100 having these characteristics or a film 190 including the same is advantageous for use as a protective layer (or cover window) for electronic devices.

[0090] The in-plane retardation Re of the elastic layer 100 may be 300 nm or less, 200 nm or less, or 100 nm or less. The in-plane retardation Re of the elastic layer may be 50 nm or less, or 45 nm or less. The in-plane retardation Re of the elastic layer may be 1 nm or more. An elastic layer having such in-plane retardation properties can be applied without a separate polarizing layer or together with a polarizing layer to simultaneously impart shock absorption properties and polarization properties to the film.

[0091] The thickness direction retardation Rth of the elastic layer 100 may be 3,000 nm or less, 1,500 nm or less, or 1,000 nm or less. The thickness direction retardation Rth of the elastic layer may be 800 nm or less, 400 nm or less, or 300 nm or less. The thickness direction retardation Rth of the elastic layer may be 1 nm or more. An elastic layer having such thickness direction retardation characteristics can be applied without a separate polarizing layer or together with a polarizing layer to simultaneously impart impact mitigation properties and polarization properties to the film.

[0092] The elastic layer 100 may be substantially free of cloudiness. The area of ​​the elastic layer where cloudiness is observed may be less than 1% of the total area. Here, the total area is based on the total area of ​​the film applied to the product. The cloudiness may be objectively evaluated through haze measurement, and a haze measurement value of more than 1% may be considered to be cloudy. The degree of cloudiness may be adjusted by controlling the degree of gelation and molecular weight distribution of the resin used to manufacture the elastic layer.

[0093] The elastic layer 100 can have good storage modulus related characteristics.

[0094] The elastic layer 100 has a storage modulus index, represented by the following formula 1, of 20 to 350 MPa.

[0095] [Formula 1] JPEG0007825346000002.jpg1063

[0096] In the above formula 1, K SM is the storage modulus index of the elastic layer, SM n is the storage modulus (Mpa) of the elastic layer measured at a temperature of n°C.

[0097] For example, SM -40 is the storage modulus (Mpa) of the elastic layer measured at a temperature of -40°C, and SM 20 is the storage modulus (Mpa) of the elastic layer measured at a temperature of 20°C, and SM 80 is the storage modulus (Mpa) of the elastic layer measured at a temperature of 80°C.

[0098] When the elastic layer has a storage modulus index of the above value, it has a relatively stable degree of change in storage modulus over a relatively wide temperature range, and therefore can have stable elastic properties over a wide temperature range.

[0099] The elastic layer 100 may have a storage modulus of 3 GPa or less at room temperature or normal temperature. The elastic layer may have a storage modulus of 2 GPa or less at room temperature or normal temperature.

[0100] The elastic layer 100 has a storage modulus at room temperature that is relatively low compared to PET films, etc. Due to this characteristic, the elastic layer or a film including the same may have more stable bending properties and may further reduce the degree to which an external impact is transmitted to an item placed on the backside.

[0101] The elastic layer 100 has a high temperature storage modulus ratio R 80 / 20 The ratio R of the high temperature storage moduli may be 0.08 or more. 80 / 20 is the ratio of the storage modulus at 80°C to the storage modulus at 20°C, and is expressed by the following formula 1-a.

[0102] [Formula 1-a] JPEG0007825346000003.jpg1034

[0103] In the formula 1-a, R 80 / 20 is the ratio of high temperature storage modulus, SM n is the storage modulus (Mpa) of the elastic layer measured at a temperature of n°C.

[0104] The elastic layer 100 has a R 80 / 20 may be 0.08 or more, 0.10 or more, or 0.15 or more. 80 / 20 The elastic layer may have a R of 0.20 or more, or may have a R of 0.25 or more. 80 / 20 may be 1 or less, or may be 0.85 or less. 80 / 20 may be 0.7 or less, or may be 0.55 or less.

[0105] R in this range 80 / 20 An elastic layer having the above characteristics is advantageous for application to bendable cover windows and the like, which are subjected to repeated bending over a wide temperature range. This characteristic is even more advantageous when the elastic layer is laminated with other layers. Specifically, when an elastic layer having the above characteristics is used, it is relatively easy to control the deterioration of physical properties that occurs due to differences in storage modulus between layers depending on temperature. In addition, the elastic layer has excellent elastic properties within a controllable range not only at room temperature but also at high temperatures.

[0106] The elastic layer 100 is R 80 / 20 The elastic layer may have a R of 0.15 to 0.55.80 / 20 may be 0.25 to 0.55. In such a case, the elastic layer has stable physical properties even after the elastic layer is bonded to another component using an adhesive layer or the like, and at the same time, the occurrence of peeling, lifting, and the like can be substantially controlled not only at room temperature but also at high temperatures.

[0107] The elastic layer 100 has a low temperature storage modulus ratio R -40 / 20 The ratio R of the low temperature storage moduli may be 1.15 or more. -40 / 20 is the ratio of the storage modulus at -40°C to the storage modulus at 20°C, and is represented by the following formula 1-b.

[0108] [Formula 1-b] JPEG0007825346000004.jpg1039

[0109] In the formula 1-b, R -40 / 20 is the ratio of the low temperature storage modulus, SM n is the storage modulus (Mpa) of the elastic layer measured at a temperature of n°C.

[0110] The elastic layer 100 is R -40 / 20 may be 1.20 or more, or may be 1.33 or more. -40 / 20 may be 20 or less, or may be 10 or less. -40 / 20 may be 4.9 or less, or may be 4.5 or less.

[0111] R in this range -40 / 20An elastic layer having the above characteristics is advantageous for application to bendable cover windows and the like, which are subjected to repeated bending over a wide temperature range. This characteristic is even more advantageous when the elastic layer is laminated with other layers. Specifically, when an elastic layer having the above characteristics is used, it is relatively easy to control the deterioration of physical properties that occurs due to the difference in storage modulus between layers depending on temperature. In addition, the elastic layer has excellent elastic properties within a controllable range not only at room temperature but also at low temperatures.

[0112] The elastic layer 100 is R -40 / 20 The elastic layer may have a R of 1.22 to 4.50. -40 / 20 The elastic layer may have a R -40 / 20 may be 1.22 to 3.0. In such a case, the elastic layer has stable physical properties even after the elastic layer is bonded to another component using an adhesive layer or the like, and at the same time, peeling and lifting can be substantially prevented not only at room temperature but also at low temperatures.

[0113] The difference in low-temperature storage modulus is the difference between the storage modulus at -40°C and the storage modulus at 20°C, and is represented by the following formula 1-c.

[0114] [Formula 1-c] JPEG0007825346000005.jpg651

[0115] In the formula 1-c, D -40-20 is the difference in low temperature storage modulus, SM n is the storage modulus (Mpa) of the elastic layer measured at a temperature of n°C.

[0116] The elastic layer 100 is D -40-20 The elastic layer may have a D -40-20 The D of the elastic layer may be in the range of -1000 MPa to 1000 MPa. -40-20If the D of the elastic layer is more than 1500 MPa, the difference in storage modulus between room temperature and low temperature is relatively large, so that the elastic properties may be substantially insufficient at low temperature, and irreversible deformation such as tearing or breaking may occur due to deformation such as bending. -40-20 may be 1000 MPa or less.

[0117] The elastic layer 100 may have a −40° C. storage modulus of 2300 MPa or less, or 2000 MPa or less. The elastic layer may have a −40° C. storage modulus of 200 MPa or more, 400 MPa or more, or 500 MPa or more.

[0118] The elastic layer 100 may have a 0°C storage modulus of 2500 MPa or less, or 2000 MPa or less. The elastic layer may have a 0°C storage modulus of 20 MPa or more, or 150 MPa or more. The elastic layer may have a 0°C storage modulus of 180 to 1200 MPa.

[0119] The elastic layer 100 may have a storage modulus at 40°C of 10 MPa or more, or 90 MPa or more. The elastic layer may have a storage modulus at 40°C of 3000 MPa or less, or 2000 MPa or less. The elastic layer may have a storage modulus at 40°C of 100 to 1200 MPa.

[0120] The elastic layer 100 may have an 80°C storage modulus of 4 MPa or more, or 20 MPa or more. The elastic layer may have an 80°C storage modulus of 2000 MPa or less, or 1000 MPa or less. The elastic layer may have an 80°C storage modulus of 40 to 950 MPa, or 60 to 350 MPa.

[0121] The elastic layer 100 may have a difference between the storage modulus at 80°C and the storage modulus at -40°C, and the difference may be -1000 MPa to 1000 MPa. For convenience, the difference may be expressed as an absolute value obtained by subtracting the smaller value from the larger value, and in this case, the difference may be 1000 MPa or less. An elastic layer having the above characteristics has a relatively small difference in storage modulus over a wide temperature range from high to low, and therefore can exhibit stable storage modulus characteristics over an extremely wide temperature range.

[0122] The elastic layer 100 having the above-described temperature-dependent storage modulus characteristics has an appropriate value and / or degree of change of storage modulus not only at room temperature or normal temperature but also in a very wide temperature range from low to high temperatures.

[0123] The elastic layer 100 can be applied alone or together with other layers to an article (such as a multi-layer electronic device) and has excellent shape recovery properties even when repeatedly deformed by bending, rolling, etc., while also providing adequate protection for the article from external impacts.

[0124] The elastic layer 100 can have good recovery / impact resistance properties, and the like.

[0125] The elastic layer 100 may have a recovery force index Rv of more than 50, as expressed by the following formula 3:

[0126] [Formula 3] JPEG0007825346000006.jpg1245

[0127] In the formula 3, Xo is the initial length of the elastic layer (mm); X 2% is the length (mm) of the elastic layer after it has been stretched by 2%, Xf is the length (mm) of the elastic layer after 100 cycles, where one cycle is stretched by 2% at a speed of 50 mm / min and then restored to its original length at a speed of 50 mm / min.

[0128] In the recovery index test, a fixing part such as a jig is applied to both ends of the elastic layer to fix the elastic layer. The initial length of the elastic layer and the length of the elastic layer after the cycles mean the length actually subjected to repeated tension, so the above-mentioned Xo and X 2% and Xf are the lengths of the elastic layer between the fixing portions, respectively.

[0129] The Rv of the elastic layer 100 may be 55 or more, 60 or more, or 68 or more. The Rv of the elastic layer may be less than 100, or may be 99 or less. The Rv of the elastic layer may be 95 or less, or may be 90 or less.

[0130] When the Rv of the elastic layer is within the above range, the elastic layer may have excellent recovery properties even after repeated stretching, and in particular, may have elastic recovery durability that allows the initial properties and length of the elastic layer to be substantially maintained even after repeated stretching and recovery over a relatively short length, such as bending.

[0131] The Rv value of the elastic layer is based on the evaluation result obtained by fixing a 100 μm thick film-like elastic layer to the fixing part (e.g., jig) of the evaluation device alone without applying a separate carrier film or support layer, but is not limited to this, and a measurement value obtained by an evaluation that is deemed equivalent to this may also be recognized as the Rv value.

[0132] The elastic layer 100 has a resistance of 2500 kJ / m 2 It may have an impact strength of 3500 kJ / m or more. 2 or have an impact strength of 4500 kJ / m or more 2 The elastic layer 100 may have an impact strength of 5000 kJ / m or more. 2 It can have an impact strength of more than 10000kJ / m 2 The elastic layer having such characteristics can absorb external impacts well and is not easily broken or damaged, making it highly usable as a cover film.

[0133] The elastic layer 100 may have an absorption energy of 1.4 J or more, or 1.5 J or more. The elastic layer 100 may have an absorption energy of 1.6 J or more, or 2.0 J or less. An elastic layer having these characteristics effectively absorbs external impacts, preventing the film itself from being easily damaged, and reduces the degree of impact transmission to the interior of the film being protected, making it highly usable as a cover film.

[0134] The impact strength and the absorption energy are based on the results of evaluating the tensile impact strength of the elastic layer in accordance with JIS K 7160, and the specific measurement conditions are based on those presented in the following experimental examples.

[0135] The elastic layer 100 can have excellent durability as a result of dynamic bending evaluation.

[0136] The dynamic bending evaluation is performed according to the IEC 62715-6-1 standard, and the elastic layer is subjected to a dynamic bending test 200,000 times at a curvature radius of 2 mm and a bending rate of 2 seconds per bending at -40°C, after which it is confirmed whether cracks occur in the elastic layer.

[0137] The elastic layer 100 may have excellent durability, with substantially no cracks occurring after a dynamic bending test of 200,000 times at a radius of curvature of 2 mm and a bending rate of 2 seconds per bending at -40°C in accordance with the IEC 62715-6-1 standard.

[0138] Considering that the elasticity at low temperatures is relatively lower than that at room temperature and high temperature, this means that the elastic layer has excellent elasticity even after repeated bending tests over a wide temperature range.

[0139] The elastic layer 100 can have properties such as excellent thickness control / surface roughness control.

[0140] The elastic layer 100 may be in the form of a film whose thickness is controlled to be substantially constant.

[0141] The elastic layer 100 may be in the form of an extruded film whose thickness is controlled to be substantially constant.

[0142] The elastic layer 100 can be laminated together with other layers described below to form a laminate film.

[0143] The term "thickness is controlled to be (substantially) constant" means that the thickness is adjusted to have a range of -5% to +5% of a predetermined thickness.

[0144] The elastic layer 100 may have a thickness of less than 2000 μm. The thickness of the elastic layer may be 1500 μm or less, or 1000 μm or less. The thickness of the elastic layer may be 1 μm or more. The thickness of the elastic layer may be 20 μm to 300 μm, or 50 μm to 300 μm.

[0145] The film-shaped elastic layer 100 having the above thickness has the above-mentioned storage modulus characteristics and also has excellent optical properties, so that it is suitable for use as a cover film for a display device.

[0146] The surface of the elastic layer 100 has a low surface roughness equal to or less than a predetermined level.

[0147] The surface roughness of the elastic layer may have technical significance by itself, but may also affect the physical properties of the elastic layer in association with other properties such as optical properties. The inventors have confirmed that the surface roughness of the elastic layer may affect the optical properties of the film, particularly maintaining the haze property at a certain level or below.

[0148] The roughness reference value is the larger value of Ra1, which is the value of the surface roughness Ra of one surface, and Ra2, which is the value of the surface roughness Ra of the other surface.

[0149] The roughness reference value of the elastic layer 100 may be 0.5 μm or less.

[0150] The roughness standard of the elastic layer 100 may be less than 0.5 μm, 0.2 μm or less, or 0.1 μm or less. The roughness standard of the elastic layer may be greater than 0 μm, 0.0001 μm or more, or 0.001 μm or more.

[0151] When the roughness reference value of the elastic layer is controlled to a certain level or less, the optical properties of the elastic layer, particularly the haze properties, can be further improved.

[0152] The standard roughness value of the elastic layer 100 may be 0.001 to 0.1 μm. The standard roughness value of the elastic layer may be 0.0015 to 0.05 μm. An elastic layer having such a standard roughness value has better optical properties such as haze and is highly usable as an optical film.

[0153] For example, one side of the elastic layer may be the side that comes into contact with the carrier film 92 described below, and the other side of the elastic layer may be the side that comes into contact with a separate sheet protection film 94 or a roll-type device (e.g., a squeezing roll) during the manufacturing process.

[0154] The Ra1 and Ra2 can be controlled by adjusting the surface roughness of the carrier film and the roll-type equipment (or sheet protection film) that are in contact with one side or the other side of the elastic sheet during the manufacturing process of the elastic layer.

[0155] For example, if the surface roughness Ra of the carrier film is in the range of 0.8 to 1.2 μm, the surface roughness Ra value of one surface of the elastic layer, Ra1, may be 0.8 to 1.2 μm.

[0156] For example, if the surface roughness Ra of the roll-type equipment is in the range of 0.01 to 0.5 μm, the surface roughness Ra2 of the other surface of the elastic layer may be in the range of 0.01 to 0.5 μm.

[0157] For example, if the surface roughness Ra of the sheet protection film is in the range of 0.01 to 0.5 μm, the surface roughness Ra value Ra2 of the other surface of the elastic layer may be in the range of 0.01 to 0.5 μm.

[0158] The carrier film 92 may be a PET (Polyethylene Terephthalate) film, but is not limited thereto.

[0159] The sheet protection film 94 may be a PE (Polyethylene) film, but is not limited thereto.

[0160] The elastic layer 100 may have a Shore D hardness of 20 to 75, or 30 to 70. This provides strength suitable for use as a cover film, and together with the elastic properties, contributes to imparting excellent impact resistance to the film.

[0161] The elastic layer 100 may have an intrinsic viscosity of 0.8 to 2.5 measured with meta-cresol at 25° C. according to ISO 307:2019.

[0162] The elastic layer 100 may have a yellow index (YI) of 1 or less. The yellow index may be a value measured using a Color Meter Ultrascan Pro manufactured by Hunterlab in YI E313 (D65 / 10) mode.

[0163] The elastic layer 100 may have a yellowness index of 2 or less after being exposed to ultraviolet light having a wavelength of 280 to 360 nm at an output of 3.0 W for 72 hours, minus the yellowness index before exposure. The elastic layer may have a yellowness index of 1 or less after being exposed to ultraviolet light having a wavelength of 280 to 360 nm at an output of 3.0 W for 72 hours, minus the yellowness index before exposure. The elastic layer may have a yellowness index of 0.1 or more after being exposed to ultraviolet light having a wavelength of 280 to 360 nm at an output of 3.0 W for 72 hours, minus the yellowness index before exposure. An elastic layer having these characteristics may have excellent ultraviolet resistance, with little or no yellowing of the coating layer even when exposed to ultraviolet light.

[0164] The elastic layer 100 can include amide residues as repeat units.

[0165] The elastic layer 100 can include a polymeric resin that includes amide residues as repeat units.

[0166] The elastic layer 100 may be a plastic film containing a polymeric resin having amide residues as repeating units.

[0167] The elastic layer 100 may be an elastomer film containing a polymer resin having amide residues as repeating units.

[0168] The amide residues may be 30 wt % or more, 50 wt % or more, or 60 wt % or more based on the total polymer resin contained in the elastic layer. The amide residues may be 80 wt % or less, or 70 wt % or less based on the total polymer resin contained in the elastic layer. When a polymer resin having these characteristics is used in the elastic layer, an elastic layer with even better mechanical properties can be provided.

[0169] The amide residue may be 92 to 97 mol % based on the total polymer contained in the elastic layer. When such a polymer is used in the elastic layer, an elastic layer having excellent strength and elastic properties can be provided over a substantially wide temperature range.

[0170] The elastic layer 100 comprises polymers, which may include stiff and soft regions in the chain.

[0171] The rigid region may be expressed as a rigid segment or a semi-crystalline region, and the soft region may be expressed as a soft segment or an amorphous region.

[0172] The polymer may contain both rigid and soft regions, allowing the elastic layer to have relatively high mechanical strength while also having flexible and / or elastomeric properties.

[0173] The elastic layer may have polymer chain regions (homologous regions) containing monomers classified as substantially the same type. By adjusting the degree of partial bonding or the degree of chain alignment in the polymer chain regions (homologous regions), the elastic layer may have both the intended strength and elastic properties. In the elastic layer, monomers classified as substantially different types may be further bonded to the polymer chain regions (homologous regions). The elastic layer may have both a rigid region with high strength in part and a soft region with soft properties that can impart flexibility to the polymer.

[0174] The elastic layer may include elastic polyamide (long chain polyamide).

[0175] The elastic polyamide may include amorphous regions, which are soft regions, and crystalline regions, which are rigid regions, and the amorphous regions may be a matrix in which the crystalline regions are distributed.

[0176] The rigid region may contain more hydrogen-bonded C=O molecules than the flexible region. The flexible region may contain more free C=O bonds that are not hydrogen-bonded than the rigid region. The content of hydrogen-bonded C=O molecules in the rigid region and the flexible region may be determined by measuring FT-IR spectra.

[0177] The elastic polyamide may comprise a semicrystalline polyamide. The elastic polyamide may comprise an amorphous polyamide. The elastic polyamide may comprise a mixture of semicrystalline and amorphous polyamides. Preferably, the elastic polyamide comprises more than 50 wt. % semicrystalline polyamide based on the total weight of the elastic polyamide.

[0178] The elastic polyamide may be a homopolyamide, a polyamide copolymer, or a mixture thereof. The elastic polyamide may be prepared as a homopolyamide by polymerizing one monomer selected from an amino acid, a lactam, or a mixture of a diacid and a diamine. The elastic polyamide may be prepared as a polyamide copolymer by polymerizing two or more monomers selected from an amino acid, a lactam, or a mixture of a diacid and a diamine.

[0179] Elastomeric polyamides can be made by combining a molecule containing an amide group at one end with another molecule containing a carboxyl group at one end.

[0180] Examples of monomers applicable to preparing elastic polyamides include, but are not limited to:

[0181] The aliphatic diacid may be, for example, but not limited to, adipic acid (6), azelaic acid (9), sebacic acid (10), dodecanedioic acid (12), and the like.

[0182] The aromatic diacid may be, for example, but not limited to, terephthalic acid (T), isophthalic acid (I), and the like.

[0183] The aliphatic diamine may be, for example, but not limited to, butylenediamine (4), hexamethylenediamine (6 or HMDA), isomers of trimethylhexamethylenediamine (TMHMDA), octamethylenediamine (8), decamethylenediamine (10), dodecamethylenediamine (12), and the like.

[0184] The aromatic diamine may be, for example, but is not limited to, meta-xylenediamine (MXD).

[0185] Examples of alicyclic diamines include bis(3,5-dialkyl-4-aminocyclohexyl)methane, bis(3,5-dialkyl-4-aminocyclohexyl)ethane, bis(3,5-dialkyl-4-aminocyclohexyl)propane, bis(3,5-dialkyl-4-aminocyclohexyl)butane, and bis(3,5-dialkyl-4-aminocyclohexyl)butane. The compound may be, but is not limited to, bis(3-methyl-4-aminocyclohexyl)methane (BMACM, MACM or B), bis(p-aminocyclohexyl)methane (PACM), isopropylidenedi(cyclohexylamine) (PACP), isophoronediamine (IPD), 2,6-bis(aminomethyl)norbornane (BAMN), piperazine, or a mixture thereof.

[0186] The other diamine may be, for example, but not limited to, isophoronediamine (IPDA), 2,6-bis-(aminomethyl)norbornane (BAMN), and the like.

[0187] The lactam may be, for example, but not limited to, caprolactam (L6), lauryllactam (L12), and the like.

[0188] The amino acid may be, for example, but is not limited to, 11-aminoundecanoic acid (11), 11-(N-heptyl-amino)undecanoic acid (NHAU), and the like.

[0189] The elastic polyamide may include an aliphatic polyamide. The elastic polyamide may consist of an aliphatic polyamide.

[0190] The elastic polyamide may include a semi-aromatic polyamide. The elastic polyamide may consist of a semi-aromatic polyamide.

[0191] Aliphatic polyamides include, for example, polycaprolactam (PA 6), polyundecanamide (PA 11), polylauryllactam (PA 12), polybutylene adipamide (PA 46), polyhexamethylene adipamide (PA 66), polyhexamethylene azelamide (PA 69), polyhexamethylene sebacamide (PA 610), polyhexamethylene dodecanediamide (PA 612), polydecamethylene dodecanediamide (PA 1012), polydecamethylene sebacamide (PA 1014), and the like. The polyamide copolymer may be, but is not limited to, poly(dodecamethylene dodecanediamide) (PA 1010), poly(dodecamethylene dodecanediamide) (PA 1212), polyamide copolymers PA 11 / NHUA, PA BACM6, PA BACM10, PA BACM12, PA 6 / 66, PA 6 / 12, or mixtures thereof. By way of example, the polyamide copolymer may be PA 6 / 66, PA 6 / 610, PA 6 / 12, or mixtures thereof.

[0192] The semi-aromatic polyamide may be, for example, but not limited to, PA 6 / 6T, PA 66 / 6T, PA 6T / 6I, PA 66 / 6T / 6I, PA 11 / 6T, PA 12 / 6T, PA MXD6, PA MXD10, or mixtures thereof.

[0193] Examples of amorphous polyamides include, but are not limited to, polyhexamethylene isophthalamide (PA 6I), polytrimethylhexamethylene terephthalamide (PA TMHMDAT), and PA BACM12 as polyamides; and amide copolymers such as PA 6 / BMACPI, PA 6 / BAMNT, PA 11 / BMACMI, PA 11 / BMACMT / BMACMI, PA 11 / BACM.I / IPDA.I, PA 12 / BMACM.I, PA 12 / BACMT / BACMI, PA 12 / BMACMT / BACMI, PA 12 / BACMI / IPDAI, PA 6T / 6I / BACMI, and PA 6T / 6I / BACMT / BACMI; or mixtures thereof.

[0194] Preferably, the polyamide is a semi-crystalline polyamide. In this specification, semi-crystalline polyamide may refer to a substantially linear aliphatic polyamide. Preferably, the semi-crystalline polyamide may be any one selected from PA 6, PA 11, PA 12, PA 10.10, PA 10.12, PA 6.10, PA 6.12, and combinations thereof.

[0195] The elastic polyamide may be, for example, Rilsan®, Rilsamid®, etc., manufactured by Arkema, but is not limited thereto.

[0196] The elastic layer 100 may include polyether block amide (PEBA). The polyether block amide includes two phases: a polyamide domain, which is a rigid region, and a polyether domain, which is a soft region. The polyamide domain has a melting point of about 80°C or higher, specifically about 130 to 180°C, and can constitute a hard region with a substantially crystalline phase. The polyether domain has a glass transition temperature of about -40°C or lower, specifically a low temperature range of -80 to -40°C, and can constitute a substantially amorphous soft region.

[0197] The polyether block amide may be a polyamide containing two or more carboxyl groups in the molecule bonded to an ether containing two or more hydroxyl groups in the molecule.

[0198] The elastic layer 100 can include a polyether block amide, which can include one or more copolymers including a polyether block and a polyamide block. The polyether block amide can include one or more polyether blocks and one or more polyamide blocks.

[0199] The copolymer containing a polyether block and a polyamide block (polyether block amide) may be a copolymer obtained by condensation polymerization of a polyether block containing a reactive end and a polyamide block containing a reactive end.

[0200] The polyether block amide may be a condensation polymer comprising a polyamide block containing a diamine terminus and a polyoxyalkylene block containing a dicarboxyl terminus.

[0201] The polyether block amide may be a condensation polymer containing a polyamide block having a dicarboxyl end group and a polyoxyalkylene block having a diamine end group. The polyoxyalkylene block may be obtained by cyanoethylation and hydrogenation of an aliphatic α,ω-dihydroxylated polyoxyalkylene block known as a polyether diol.

[0202] The polyether block amide may be a condensation polymer comprising a polyamide block containing a dicarboxyl end group and a polyether diol block, in which case the polyether block amide is a polyetherester amide.

[0203] Illustratively, polyamide blocks containing dicarboxylic chain ends can comprise condensation polymers of polyamide precursors in the presence of a chain-limiting dicarboxylic acid. Illustratively, polyamide blocks containing diamine chain ends can comprise condensation polymers of polyamide precursors in the presence of a chain-limiting diamine.

[0204] For example, the polyamide block containing dicarboxylic chain ends may comprise a condensation polymer of an α,ω-aminocarboxylic acid, a lactam, or a dicarboxylic acid with a diamine in the presence of a chain-limiting dicarboxylic acid, preferably polyamide 12 or polyamide 6.

[0205] The polyether block polyamide may comprise blocks having randomly distributed unit structures.

[0206] Advantageously, three types of polyamide blocks may be applied:

[0207] In the first type, the polyamide block may comprise a condensation polymer of a carboxylic acid and an aliphatic or arylaliphatic diamine. The carboxylic acid may have 4 to 20 carbon atoms, preferably 6 to 18 carbon atoms. The aliphatic or arylaliphatic diamine may have 2 to 20 carbon atoms, preferably 6 to 14 carbon atoms.

[0208] The dicarboxylic acid may be, for example, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexyldicarboxylic acid, 1,4-butanedioic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, or a dimerized fatty acid.

[0209] Examples of the diamine include 1,5-tetramethylenediamine, 1,6-hexamethylenediamine, 1,10-decamethylenediamine, 1,12-dodecamethylenediamine, trimethyl-1,6-hexamethylenediamine, 2-methyl-1,5-pentamethylenediamine, and the isomers of bis(3-methyl-4-aminocyclohexyl)methane. bis(3-methyl-4-aminocyclohexyl)methan (BMACM), 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), bis(para-aminocyclohexyl)methane (PACM), isophoronediamine (IPD), 2,6-bis(aminomethyl)norbornane (BAMN), piperazine (Pip), meta-xylylenediamine (MXD), and para-xylylenediamine (PXD).

[0210] Advantageously, the first type of polyamide blocks may comprise PA 412, PA 414, PA 418, PA 610, PA 612, PA 614, PA 618, PA 912, PA 1010, PA 1012, PA 1014, PA 1018, MXD6, PXD6, MXD10 or PXD10.

[0211] A second type of polyamide block may comprise a condensation polymer of one or more α,ω-aminocarboxylic acids and / or one or more lactams having 6 to 12 carbon atoms in the presence of a dicarboxylic acid or diamine having 4 to 12 carbon atoms.

[0212] Examples of the lactam include caprolactam, oenantholactam, and lauryllactam.

[0213] Examples of the α,ω-aminocarboxylic acid include aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acids.

[0214] Advantageously, the second type of polyamide block may comprise polyamide 11, polyamide 12 or polyamide 6.

[0215] A third type of polyamide block may comprise a condensation polymer of one or more α,ω-aminocarboxylic acids (or one or more lactams), one or more diamines and one or more dicarboxylic acids.

[0216] In such cases, the polyamide (PA) block may be prepared by condensation polymerization of a diamine, a diacid and a comonomer (or comonomers) such as:

[0217] The diamine may be, for example, a linear aliphatic diamine, an aromatic diamine, or a diamine having X carbon atoms. The diacid may be, for example, a dicarboxylic acid or an acid having Y carbon atoms. The comonomer or comonomers {Z} may be selected from lactams having Z carbon atoms, α,ω-aminocarboxylic acids, and mixtures containing one or more diamines having X carbon atoms and one or more dicarboxylic acids having Y carbon atoms in substantially equal molar amounts. However, (X1, Y1) is different from (X, Y).

[0218] Said comonomer or comonomers {Z} may comprise up to 50% by weight, preferably up to 20% by weight, advantageously up to 10% by weight, based on the total combined polyamide precursor monomers.

[0219] The condensation reaction according to said third type may be carried out in the presence of a chain limiter selected from dicarboxylic acids.

[0220] Advantageously, as chain limiter, a dicarboxylic acid having Y carbon atoms can be used, said dicarboxylic acid being introduced in a stoichiometric excess relative to said one or more diamines.

[0221] As an alternative to the third type, the polyamide block may comprise a condensation polymer of two or more α,ω-aminocarboxylic acids having 6 to 12 carbon atoms, or two or more lactams, or lactams and aminocarboxylic acids having different numbers of carbon atoms, optionally in the presence of a chain limiter.

[0222] The aliphatic α,ω-aminocarboxylic acid may be, for example, aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, or the like.

[0223] The lactam may be, for example, caprolactam, oenantholactam, lauryllactam, and the like.

[0224] The aliphatic diamine may be, for example, hexamethylenediamine, dodecamethylenediamine, trimethylhexamethylenediamine, or the like.

[0225] The alicyclic diacid may be, for example, 1,4-cyclohexanedicarboxylic acid.

[0226] The aliphatic diacid may be, for example, butanedioic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid, dimer fatty acid (preferably having a dimer content of 98% or more; preferably hydrotreated; sold under the trade name Pripol by Uniqema or the trade name Empol by Henkel), polyoxyalkylene-α,ω-dioic acid, and the like.

[0227] The aromatic diacid may be, for example, terephthalic acid (T), isophthalic acid (I), and the like.

[0228] The alicyclic diamine may be, for example, an isomer of bis(3-methyl-4-aminocyclohexyl)methane (BMACM) and 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), bis(para-aminocyclohexyl)methane (PACM), or the like.

[0229] The other diamine may be, for example, isophoronediamine (IPD), 2,6-bis(aminomethyl)norbornane (BAMN), piperazine, and the like.

[0230] Examples of arylaliphatic diamines include, but are not limited to, meta-xylylenediamine (MXD) and para-xylylenediamine (PXD).

[0231] Examples of the third type of polyamide blocks include PA 66 / 6, PA 66 / 610 / 11 / 12, etc.

[0232] In the PA 66 / 6, the 66 represents a hexamethylenediamine unit condensed with adipic acid, and the 6 represents a unit introduced by condensation of caprolactam.

[0233] In the PA 66 / 610 / 11 / 12, the 66 represents a hexamethylenediamine unit condensed with adipic acid, the 610 represents a hexamethylenediamine unit condensed with sebacic acid, the 11 represents a unit introduced by condensation of aminoundecanoic acid, and the 12 represents a unit introduced by condensation of lauryllactam.

[0234] The number average molar mass (Mn) of the polyamide blocks may be 400 to 20,000 g / mol, preferably 500 to 10,000 g / mol.

[0235] The polyether (PE) block may be, for example, one or more polyalkylene ether polyols, particularly polyalkylene ether diols, such as polyethylene glycol (PEG), polypropylene glycol (PPG), polytrimethylene glycol (PO3G), polytetramethylene glycol (PTMG), and mixtures or copolymers thereof. The polyether block may contain a polyoxyalkylene sequence containing an NH chain end, which may be introduced by cyanoacetylating an aliphatic α,ω-dihydroxypolyoxyalkylene sequence known as a polyether diol. Specifically, Jeffamine (e.g., Jeffamine® D400, D2000, ED2003, or XTJ542, available from Huntsman) may be used.

[0236] The one or more polyether blocks preferably comprise one or more polyethers selected from polyalkylene ether polyols such as PEG, PPG, PO3G, and PTMG; polyethers containing NH2 at the chain end and containing polyoxyalkylene sequences; copolymers (ether copolymers) in which these are arranged in a random and / or block fashion; and mixtures thereof.

[0237] The polyether block may be contained in an amount of 10 to 80% by weight, preferably 20 to 60% by weight, more preferably 20 to 40% by weight, based on the total weight of the copolymer.

[0238] The number average molecular weight of the polyether block may be 200 to 1000 g / mol (excluding the critical point), preferably 400 to 800 g / mol (including the critical point), more preferably 500 to 700 g / mol.

[0239] The polyether block can be derived from polyethylene glycol. The polyether block can be derived from polypropylene glycol. The polyether block can be produced from polytetramethylene glycol. The polyether block can be copolymerized with a polyamide block containing a carboxyl end to form a polyether block amide. The polyether block can be aminated to convert it to a polyether diamine and then condensed with a polyamide block containing a carboxyl end to form a polyether block amide. The polyether block can be mixed with a polyamide precursor and a chain limiter to form a polyether block amide containing statistically dispersed units.

[0240] Examples of polyethers include polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene glycol (PTMG). Polytetramethylene glycol is also known as polytetrahydrofuran (PTHF). Polyether blocks can be introduced into the polyether block amide chain from the form of diols or diamines, and the polyether blocks are called PEG blocks, PPG blocks, and PTMG blocks, respectively.

[0241] Even if the polyether block contains units other than units derived from ethylene glycol (-OC2H4-), propylene glycol (-O-CH2-CH(CH3)-), or tetramethylene glycol (-O-(CH2)4-), the polyether block is within the scope of the embodiment.

[0242] The number-average molar mass of the polyamide blocks may advantageously be between 300 and 15,000, preferably between 600 and 5000. The number-average molar mass of the polyether blocks may be between 100 and 6000, preferably between 200 and 3000.

[0243] Advantageously, the content of polyamide blocks contained in the polyether block amide may be 30% by weight or more, or 50% by weight or more, based on the entire polyether block amide. This may refer to the possibility of statistical distribution in the polymer chain. The content of the polyamide is preferably 30 to 80% by weight or 50 to 80% by weight. The content of polyether contained in the polyether block amide is preferably 20 to 70% by weight or 20 to 50% by weight, based on the entire polyether block amide.

[0244] Preferably, the ratio of the number average molar mass of the polyamide block to the number average molar mass of the polyether block of the copolymer may be 1:0.25 to 1, and the number average molar masses of the polyamide block and the polyether block of the copolymer may be 1000 / 1000, 1300 / 650, 2000 / 1000, 2600 / 650, or 4000 / 1000, respectively.

[0245] The polyether block amide may be produced by a production method including a first step of producing a polyamide block and a polyether block, and a second step of condensation polymerizing the produced polyamide block and polyether block to produce an elastic polyether block amide. The polyether block amide may also be produced by condensation polymerizing monomers in a single step.

[0246] The polyether block amide may illustratively exhibit a Shore D hardness of 20 to 75, preferably 30 to 70. The polyether block amide may have an intrinsic viscosity of 0.8 to 2.5 as measured in meta-cresol at 25°C. The intrinsic viscosity is measured in accordance with ISO 307:2019. Specifically, the intrinsic viscosity in solution is measured using an Ubbelohde viscometer at 25°C in a 0.5 wt% meta-cresol solution relative to the total solution.

[0247] Examples of the polyether block amide include, but are not limited to, Pebax (registered trademark) and Pebax (registered trademark) Rnew (registered trademark) from ARKEMA, and VESTAMID (registered trademark) E from EVONIK.

[0248] The elastic layer 100 may comprise thermoplastic polyurethane (TPU), a copolymer of polyurethane blocks (PU) and polyether blocks (PE), also called polyetherurethane.

[0249] TPU may be a condensation polymer containing a soft PE block, a polyether diol or polyester diol (e.g., poly(butyladipate) or polycaprolactone diol), and a hard PU block. The PU and PE blocks may be linked by bonds formed by the reaction of the isocyanate groups of the polyether with the hydroxyl groups of the polyether diol.

[0250] As used herein, polyurethane refers to a product formed by the reaction of one or more diisocyanates, which may be selected from aromatic diisocyanates (e.g., MDI, TDI) and / or aliphatic diisocyanates (e.g., HDI or hexamethylenediisocyanate), with one or more short chain length diols (e.g., butanediol, ethylene glycol).

[0251] The elastic layer may include a copolyetherester (COPE).

[0252] The COPE may comprise a thermoplastic elastomeric polymer containing one or more polyether blocks (PE) and one or more polyester blocks (homopolymer or ester copolymer).

[0253] COPEs can include a flexible PE block derived from a polyether diol and a rigid polyester block formed from the reaction of one or more dicarboxylic acids with one or more short-chain extender diol units. The PES and PE blocks can be linked by ester bonds introduced by the reaction of the acid groups of the dicarboxylic acids with the hydroxyl groups of the polyether diol. The short-chain extender diol is a copolymer of neopentyl glycol and a carboxylic acid having the formula HO(CH2). n aliphatic glycols of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 39, 38,

[0254] The polyether and diacid chains form the flexible blocks, while the diacid chains and glycol or butanediol chains form the rigid blocks of the polyetherester copolymer. Advantageously, the diacid may be an aromatic dicarboxylic acid having 8 to 14 carbon atoms. The aromatic dicarboxylic acid may be replaced by one or more other aromatic dicarboxylic acids having 8 to 14 carbon atoms in an amount of up to 50 mol % of the total aromatic dicarboxylic acid, and / or by one or more aliphatic dicarboxylic acids having 2 to 14 carbon atoms in an amount of up to 20 mol % of the total aromatic dicarboxylic acid.

[0255] The aromatic dicarboxylic acid may be, for example, terephthalic acid, isophthalic acid, dibenzoic acid, naphthalene dicarboxylic acid, 4,4'-diphenylenedicarboxylic acid, bis(p-carboxyphenyl)methane acid, ethylene bis(p-benzoic acid), 1,4-tetramethylene bis(p-oxybenzoic acid), ethylene bis(p-oxybenzoic) acid, 1,3-trimethylene bis(p-oxybenzoic) acid, or the like.

[0256] Examples of glycols include ethylene glycol, 1,3-trimethylene glycol, 1,4-tetramethylene glycol, 1,6-hexamethylene glycol, 1,3-propylene glycol, 1,8-octamethylene glycol, and 1,10-decamethylene glycol.

[0257] COPE can contain polyether units derived from polyether diols such as polyethylene glycol (PEG), polypropylene glycol (PPG), polytrimethylene glycol (PO3G), or polytetramethylene glycol (PTMG), and polyester units introduced by reacting a dicarboxylic acid (e.g., terephthalic acid) with a glycol (e.g., ethanediol, 1,4-butanediol). Such polyetherester copolymers are disclosed in European Patents EP 402883 and EP 405227, the contents of which are incorporated herein by reference.

[0258] The elastic layer can include the polyamide, the PEBA, the TPU, the COPE, or a mixture thereof.

[0259] A method for producing the elastic layer using a polymer resin will be described later.

[0260] Film, film uses According to another embodiment, the film 190 includes an elastic layer 100 .

[0261] The light-transmitting laminate according to another embodiment includes an elastic layer 100 .

[0262] The cover film according to another embodiment includes an elastic layer 100 .

[0263] The above description is applicable to the specific description of the elastic layer 100, and detailed description will be omitted to avoid duplication.

[0264] The film 190 may include a laminate further including a carrier film 92 positioned on one side 100a of the elastic layer.

[0265] The carrier film 92 may be a film having a thickness of 50 μm, and a PET film may be used in consideration of various aspects such as chemical resistance and dimensional stability.

[0266] The carrier film 92 may be, for example, a PET film having a thickness of 50 to 250 μm.

[0267] The carrier film 92 can also serve as a release film 150, which will be described later.

[0268] One side of the carrier film 92 can be in direct contact with the elastic layer 100 .

[0269] During the manufacturing process of the elastic layer 100, the surface roughness of one surface of the carrier film 92 can be transferred to the surface of the elastic layer that is in contact with it.

[0270] The surface roughness Ra of one surface of the carrier film 92 may be 0.5 μm or less, or 0.2 μm or less, or may be greater than 0 μm, or may be 0.0001 μm or more, or may be 0.001 μm or more.

[0271] The surface roughness Ra of one surface of the carrier film 92 may be 0.001 to 0.1 μm. A carrier film having such roughness controls the surface roughness of the elastic layer, making it possible to provide an elastic layer with a lower haze value.

[0272] The film 190 may include a film laminate including the elastic layer 100 and the carrier film 92. The carrier film may serve as a release film.

[0273] The film 190 may comprise a laminate further comprising an elastic layer 100 and a sheet protection film 94 positioned on the elastic layer.

[0274] The film 190 may further include a sheet protection film 94 positioned on the other surface 100b of the elastic layer.

[0275] For example, a PE film or a PET film may be used as the sheet protection film 94. The thickness of the sheet protection film is not particularly limited.

[0276] One side of the sheet protection film can be in direct contact with the other side 100b of the elastic layer. When the sheet protection film is applied during the manufacturing process of the elastic layer, the surface roughness of one side of the sheet protection film can control the surface roughness of the other side of the elastic layer.

[0277] The surface roughness Ra of one surface of the sheet protection film 94 may be 0.5 μm or less, or 0.2 μm or less, or may be greater than 0 μm, 0.0001 μm or more, or 0.001 μm or more.

[0278] The surface roughness Ra of one surface of the sheet protection film may be 0.001 to 0.1 μm. A sheet protection film with such a roughness can control the surface roughness of the elastic layer, providing an elastic layer with a lower haze value.

[0279] The film 190 may include a laminate of an elastic layer 100 and a sheet protection film 94 positioned on the elastic layer.

[0280] The film 190 may include a laminate of a carrier film 92, an elastic layer 100 positioned on the carrier film, and a sheet protection film 94 positioned on the elastic layer.

[0281] The laminate may be a light-transmitting laminate, which as used herein means a laminate having a light transmittance of 85% or more.

[0282] The film 190 may include a hardness layer 120 disposed on the elastic layer 100 .

[0283] The resilient layer 100 may be disposed on the hardness layer 120 .

[0284] The film 190 may include an adhesive layer 130 located between the hardness layer 120 and the elastic layer 100. The adhesive layer 130 will be described in detail later.

[0285] The film 190 may not include a separate adhesive layer between the elastic layer 100 and the hardness layer 120. In this case, the elastic layer 100 may be attached to the hardness layer 120 by a fusion bonding method.

[0286] The hard layer 120 is a layer having a surface hardness of H or more.

[0287] The hardness layer 120 may have a surface hardness of H or more, 3H or more, or 4H or more as measured by the pencil hardness method.

[0288] The hardness layer 120 may be a polyimide film, a glass layer, or a laminate thereof.

[0289] The polyimide film may be a layer made of a polyamide-imide polymer. Since the layer made in this way contains imide repeating units, it may be broadly classified as a polyimide film.

[0290] The polyamide-imide polymer includes a polymer formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound, and a dicarbonyl compound. Specifically, the polyamide-imide polymer can be obtained by polymerizing an aromatic diamine compound, an aromatic dianhydride compound, and a dicarbonyl compound in an organic solvent.

[0291] The aromatic diamine compound may include 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFMB), 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP), 4,4′-diamino-2,2′-bis(trifluoromethyl)diphenyl ether (BTFDPE), 2,2-bis(4-(4-amino-2-(trifluoromethyl)phenoxy)phenyl)hexafluoropropane (HFFAPP), or 3,5-diaminobenzotrifluoride (DATF).

[0292] Specifically, the aromatic diamine compound may be a compound represented by the following chemical formula 1-1.

[0293] [ka]

[0294] The aromatic dianhydride compound can include 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6-FDA), 4,4'-oxydiphthalic acid dianhydride (ODPA), or 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (BPDA).

[0295] Specifically, the aromatic dianhydride compound may be a compound represented by the following chemical formula 2-1.

[0296] [ka]

[0297] The aromatic diamine compound and the aromatic dianhydride compound can be reacted in a molar ratio of 1:0.95 to 1.05 to form a polymer.

[0298] The dicarbonyl compound may be a compound represented by the following chemical formula 3-1 or 3-2.

[0299] [ka] [ka]

[0300] The aromatic diamine compound and the dicarbonyl compound can be reacted in a molar ratio of 1:0.95 to 1.05 to form a polymer.

[0301] The polyimide film can contain at least one of the repeating units represented by the following chemical formulas 4-1 to 4-3.

[0302] [ka]

[0303] In the above Chemical Formula 4-1, the n is an integer of 1 to 400.

[0304] [ka]

[0305] In the above Chemical Formula 4-2, the x is an integer of 1 to 400.

[0306] [ka]

[0307] In the above Chemical Formula 4-3, the y is an integer of 1 to 400.

[0308] The polyimide film may contain imide repeat units and amide repeat units in a molar ratio of 1:1-4.

[0309] Polyimide films can have excellent transparency as well as excellent mechanical properties, chemical resistance, and heat resistance.

[0310] The polyimide film may have a modulus of 5.0 GPa or more based on a thickness of 50 μm.

[0311] The polyimide film may have a yellowness index of 5 or less based on a thickness of 50 μm.

[0312] The polyimide film may have a haze of 2% or less based on a thickness of 50 μm.

[0313] The polyimide film may be a transparent polyimide film.

[0314] The polyimide film may have a light transmittance of 85% or more when measured at 550 nm based on a thickness of 50 μm.

[0315] The polyimide film has a tensile strength of 15 kgf / mm based on a thickness of 50 μm. 2 It may be more than that.

[0316] The polyimide film may have an elongation of 15% or more based on a thickness of 50 μm.

[0317] The polyimide film may further include a hard coating layer on the polyimide layer.

[0318] The hard coating layer can be applied without any limitation as long as it can be applied to a hard coating layer of a polyimide film.

[0319] The glass layer may be made of ultra-thin glass (UTG), which has heat resistance and insulation properties and a small radius of curvature. The ultra-thin glass may be, but is not limited to, a cover window product type from Dow Corning, Dow Corning, Dow Corning, Schott, etc. For example, the glass layer may have a thickness of 100 μm or less and a radius of curvature of 2 mm or less.

[0320] The film 190 may further include an adhesive layer 130' disposed opposite the elastic layer 100 with the hardness layer 120 sandwiched therebetween. The adhesive layer 130' will be described later, so a detailed description thereof will be omitted.

[0321] The film 190 may further include a release film 150 disposed opposite the hardening layer 120 with the adhesive layer 130' sandwiched therebetween. When the film further includes a release film, the process of adhering to other layers may be facilitated. The description of the release film is omitted as it overlaps with the above description.

[0322] The film 190 may further include an adhesive layer 130 on one or the other side of the elastic layer, if desired.

[0323] An optical adhesive layer having excellent light transmittance and / or transparency may be applied as the adhesive layer 130. For example, adhesive materials including an optically clear adhesive (OCA), a pressure sensitive adhesive (PSA), or a combination thereof may be applied.

[0324] The adhesive layer 130 may have a difference between its storage modulus at 80°C and its storage modulus at -40°C, and the difference between the two storage moduli may be -100 to 100 kPa, or -80 to 80 kPa. The adhesive layer 130 may have a storage modulus at -40°C minus its storage modulus at 80°C of 0.01 to 100 kPa, 0.1 to 80 kPa, or 1 to 50 kPa. When an adhesive layer 130 having such storage modulus characteristics is applied to the film 190, the elastic recovery force and elastic durability of the film can be further improved, making it particularly useful when applied as a window cover for a flexible or rollable display.

[0325] The elastic layer 100 may be disposed on a release film 150. An adhesive layer may be disposed between the elastic layer and the release film. In this case, the film 190 may be a laminate in which the release film 150, the adhesive layer 130, and the elastic layer 100 are sequentially laminated.

[0326] The release film 150 may be, for example, a PET film, but is not limited to this. Alternatively, the above-described carrier film 92 or sheet protection film 94 may be used as the release film 150.

[0327] Optical properties of layers contained in film 190 Not only the elastic layer included in the film 190, but also layers other than the elastic layer can have excellent optical properties.

[0328] The refractive index of the elastic layer 100 may be less than the refractive index of the hardness layer 120 .

[0329] The refractive index of the elastic layer 100 may be less than the refractive index of the adhesive layers 130, 130'.

[0330] The difference between the refractive index of the elastic layer 100 and the refractive index of the hardness layer 120 may be 0.2 or less, or 0.1 or less, or 0.00001 or more.

[0331] The difference between the refractive index of the elastic layer 100 and the refractive index of the adhesive layers 130, 130' may be 0.2 or less, or 0.1 or less, or 0.00001 or more.

[0332] The hardness layer 120 may have a refractive index of 1.55 to 1.75. The hardness layer 120 may have a refractive index of 1.55 to 1.70, 1.58 to 1.68, 1.60 to 1.68, 1.62 to 1.66, or 1.62 to 1.65.

[0333] The hardness layer may further contain an additive such as a filler to adjust the refractive index. The filler may be, for example, particles having an average particle size of 160 nm or less, or barium sulfate particles.

[0334] The hardness layer 120 may have a haze of 1% or less. The hardness layer 120 may have a haze of 0.8% or less, 0.6% or less, or 0.5% or less.

[0335] The light transmittance of the hardness layer 120 may be 80% or more. For example, the light transmittance of the hardness layer may be 85% or more, 88% or more, 89% or more, 80% to 99%, 85% to 99%, or 88% to 99%.

[0336] The yellow index of the hardness layer 120 is 5 or less. For example, the yellow index may be 4 or less, 3.5 or less, or 3 or less.

[0337] The tensile strength of the hard layer 120 is 14 kgf / mm 2 Specifically, the tensile strength may be 16 kgf / mm or more. 2Above, 18kgf / mm 2 Over 20kgf / mm 2 Above, 21kgf / mm 2 or more, or 22kgf / mm 2 It may be more than that.

[0338] The film 190 may optionally further include a hard coating layer, a polarizing layer, a sensor layer, etc., disposed above or below the elastic layer.

[0339] The film 190 may further include a hard coating layer 140 disposed on the elastic layer.

[0340] The hard coating layer 140 may be a hard coating layer applied to a display, and can be applied without any restrictions as long as it does not cause lifting or the like in a bending test, which will be described later.

[0341] The film 190 may further include a polarizing layer 360 .

[0342] The polarizing layer 360 may be disposed under one surface 100a of the elastic layer. In this case, the film 190 may include a laminate in which the polarizing layer 360 and the elastic layer 100 are stacked. Alternatively, the film 190 may include a laminate in which the polarizing layer 360, the hardness layer 120, and the elastic layer 100 are stacked in order. In this case, adhesive layers 130 and 130' may be disposed between the polarizing layer and the elastic layer, between the polarizing layer and the hardness layer, and / or between the hardness layer and the elastic layer. In addition, if no adhesive layer is disposed, adjacent layers may be adhered by a hot-melt method.

[0343] The film 190 may further include a sensor layer 340 .

[0344] The film 190 may include a laminate in which a sensor layer 340 and an elastic layer 100 are stacked. Alternatively, the film 190 may include a laminate in which a sensor layer 340, a polarizing layer 360, and an elastic layer 100 are stacked in sequence. Alternatively, the film 190 may include a laminate in which a sensor layer 340, a hardness layer 120, and an elastic layer 100 are stacked in sequence. Alternatively, the film 190 may include a laminate in which a sensor layer 340, a polarizing layer 360, a hardness layer 120, and an elastic layer 100 are stacked in sequence. In this case, adhesive layers 130 and 130′ may be disposed between the sensor layer and the elastic layer, between the sensor layer and the polarizing layer, between the sensor layer and the hardness layer, between the polarizing layer and the hardness layer, and / or between the hardness layer and the elastic layer, respectively. If no adhesive layer is disposed, adjacent layers may be adhered by a melt adhesion method.

[0345] The film 190 can be impact resistant, etc.

[0346] In accordance with the IEC 62715-6-1 standard, the elastic layer of the film 190 is subjected to a dynamic bending test 200,000 times at a curvature radius of 2 mm and bending for 2 seconds per bending at -40°C, after which no lifting occurs at the interface where the elastic layer 100 adheres to other layers. Considering that elasticity at low temperatures is relatively lower than that at room temperature or high temperature, this means that the elastic layer has excellent recovery strength even after repeated bending tests over a wide temperature range.

[0347] Film 190 is 2500kJ / m 2 The film 190 can have an impact strength of 3500 kJ / m or more. 2 or have an impact strength of 4500 kJ / m or more 2 The film 190 may have an impact strength of 5000 kJ / m or more. 2 It can have an impact strength of more than 10000kJ / m 2 The film may have the following impact strength: A film having such characteristics can absorb external impacts well and is not easily broken or damaged, making it highly suitable for use as a cover film.

[0348] The film 190 may have an absorption energy of 1.4 J or more. The film 190 may have an absorption energy of 1.5 J or more. The film 190 may have an absorption energy of 1.6 J or more, and may have an absorption energy of 2.0 J or less. A film having these characteristics effectively absorbs external impacts, preventing the film itself from being easily damaged, and reduces the degree of impact transmission to the interior that it protects, making it highly usable as a cover film.

[0349] The difference in yellowness index of the film 190 before and after 72 hours of UV irradiation at 3.0 W with UVB 280 to 360 nm may be 2 or less, or may be less than 1. The difference in yellowness index of the film may be 0.8 or less, or may be 0.6 or less. The difference in yellowness index of the film may be 0.01 to 0.6, or may be 0.01 to 0.45. Film 190 with these characteristics can maintain excellent optical properties without yellowing even when exposed to strong UV rays for a long period of time.

[0350] The film 190 may have a haze of 2% or less, or 1% or less. The film may have a haze of 0.8% or less, or 0.7% or less. The film may have a haze of 0.01% or more. When the film 190 has such haze characteristics, it can have excellent optical properties and transparency.

[0351] The light-transmitting laminate has the same characteristics as the above-mentioned film 190. A specific description of the light-transmitting laminate will be omitted as it overlaps with the above description.

[0352] The cover film has the same characteristics as the above-mentioned film 190. A detailed description of the cover film will be omitted as it overlaps with the above description.

[0353] An application for the film 190 may be a cover window for multi-layer electronic equipment.

[0354] The film 190 may be applied as a cover layer for a display device.

[0355] The cover layer is a layer that forms the outer shape of at least a part of the device and protects the internal equipment, and is not necessarily limited to being disposed on the outermost periphery of the equipment. In particular, when the cover layer is disposed in the display area of ​​the display, it is called a cover window.

[0356] The film 190 may be used as a cover layer for bendable or foldable multi-layer electronic equipment where a portion of the device is folded.

[0357] The film 190 may be used as a cover layer for a rollable device that allows part or all of the device to be reversibly wound and unwound.

[0358] The film 190 may be included in a protective film for the display.

[0359] When film 190 is applied as a protective film for the display, it has an appropriate level of storage modulus value over a wide temperature range, and therefore, together with stable bending or flexible properties over a wide temperature range, the elastic layer can further reduce the degree of impact transmitted to the protected item.

[0360] The film 190 can have excellent durability and recovery even in repeated bending or flexible environments.

[0361] The film 190 employs an elastic layer 100 having a storage modulus change rate that is relatively stable over a wide temperature range, thereby preventing the occurrence of lifting between the elastic layer and a layer in direct contact with the elastic layer. Lifting can occur due to differences in modulus between the elastic layer and a layer in direct contact with the elastic layer during repeated bending, folding, etc. However, the elastic layer has excellent optical properties suitable for use in displays, and at the same time, it controls the storage modulus characteristics to significantly prevent the occurrence of lifting.

[0362] The film 190 is disposed on the light source outside the polarizing layer and can play a role in protecting the light emitting layer 320 (display element).

[0363] The film 190 is placed over the light source to protect the light-emitting layer 320 (display element) and can also act as a polarizing layer.

[0364] The film 190 may be disposed on one side of the light-emitting functional layer 300 including the light-emitting layer 320 performing a light-emitting function and / or the sensor layer 340 performing a sensing function such as a touch sensor in the multi-layer electronic equipment 900. The film 190 may be used to protect the light-emitting functional layer 300.

[0365] The film 190 can be disposed as a support layer for a light source and can have the purpose of being a heat-resistant support layer.

[0366] The film 190 may be used as a support layer in a display device.

[0367] The support layer refers to a layer that forms the outer shape of at least a part of the device and plays a role in supporting the light source device and the like, and is not necessarily limited to a layer that is disposed on the outermost periphery of the equipment.

[0368] The film 190 may be used as a support layer for bendable or foldable multi-layer electronic equipment where a portion of the device is folded.

[0369] The film 190 may be used as a support layer for a rollable device that can be reversibly wound and unwound in part or in whole.

[0370] The light-transmitting laminate has the same uses as the film 190 described above.

[0371] The cover film has the same uses as the film 190 described above.

[0372] Figure 4 is a cross-sectional view illustrating the configuration of a multi-layer electronic device according to an embodiment, Figures 5(a), 5(b), and 5(c) are cross-sectional views illustrating the configuration of a multi-layer electronic device according to an embodiment, and Figure 6 is a cross-sectional view illustrating the configuration of a multi-layer electronic device according to an embodiment. The multi-layer electronic device will be described in detail with reference to Figures 4 to 6.

[0373] Multi-layer electronic equipment 900 In another embodiment, the multi-layer electronic equipment 900 includes an elastic layer 100 .

[0374] In another embodiment, the multi-layer electronic equipment 900 includes a film 190 .

[0375] In another embodiment, the multi-layer electronic device 900 includes a light-transmitting laminate.

[0376] The multi-layer electronic equipment 900 may be a display device, for example, a large-area display device, a foldable display device, a bendable display device, or a flexible display device. The multi-layer electronic equipment 900 may be a bendable mobile communication device (for example, a mobile phone) or a bendable notebook computer.

[0377] The specific details of the elastic layer 100 and the film 190 are the same as those described above, and therefore will not be described again.

[0378] The multi-layer electronic device 900 according to one embodiment includes a light-emitting functional layer and a film, the light-emitting functional layer has a display area that emits or does not emit light according to an external signal, and the film may be disposed on the top or back surface of the display area.

[0379] The multi-layer electronic device 900 according to one embodiment may include a light-emitting functional layer and a film. The light-emitting functional layer may have a display area that emits or does not emit light according to an external signal. The film may be disposed on one surface of the light-emitting functional layer and cover at least a portion of the display area.

[0380] The multi-layer electronic equipment 900 may include a film 190 disposed above or below the light-emitting functional layer 300 .

[0381] The light-emitting functional layer 300 includes a light-emitting layer 320 .

[0382] The light-emitting layer 320 includes elements that emit light in response to a signal in a display device. The light-emitting layer 320 may include, for example, a signal transmission layer 322 that transmits an external electrical signal to a color-emitting layer, a color-emitting layer 324 disposed on the signal transmission layer and emitting color in response to the applied signal, and an encapsulation layer 326 that protects the color-emitting layer. The signal transmission layer 322 may include a thin film transistor (TFT), for example, but not limited to, an LTPS, a-Si TFT, or an oxide TFT. The encapsulation layer 326 may include, but is not limited to, a thin film encapsulation (TFE).

[0383] The light-emitting layer 320 may be disposed on a support layer 380. The support layer 380 may be a layer having insulating and heat-resistant properties, and may be, for example, a polyimide film, a glass layer, etc. The above-described film 190 may be used as the support layer.

[0384] The light-emitting functional layer 300 may further include a sensor layer 340. The sensor layer 340 may be a touch sensor or the like.

[0385] The light-emitting functional layer 300 may further include a polarizing layer 360. The polarizing layer 360 may be disposed on the light-emitting layer 320 or on the sensor layer 340.

[0386] In the multi-layer electronic equipment 900 , the elastic layer 100 or film 190 can be adhered onto the light-emitting functional layer 300 .

[0387] In the multi-layer electronic device 900, the elastic layer 100 or film 190 can be used as a cover film to protect the light-emitting layer 320 (display element). In addition, the elastic layer 100 or film 190 has excellent optical properties, excellent elastic recovery over a wide temperature range, and excellent durability, so that it can significantly reduce the occurrence of lifting even during repeated bending and folding, etc., and therefore is highly usable as a window cover or protective film.

[0388] In addition, the elastic layer 100 complements the protective function (function of protecting the inside of the cover film from external impact) that is insufficient when using a polyimide film alone as a hardness layer, and maintains the protective function of a cover window that uses existing glass, etc., while having rolling and bending durability that is considered insufficient for existing cover windows such as glass, etc., making it highly usable as a cover layer, protective film, etc. for multi-layer electronic equipment.

[0389] Method for manufacturing elastic layer 100 or film 190 A manufacturing method of the elastic layer 100 according to the embodiment includes the steps of forming a polymer resin into an elastic sheet, and passing the assembly in which the elastic sheet 80 is disposed on the carrier film 92 between rollers to form the elastic layer 100.

[0390] The polymer resin may contain an amide or its residue as a repeating unit. Specific descriptions of the repeating unit and polymerization of the polymer resin are omitted here because they overlap with the descriptions of the elastic layer.

[0391] The manufacturing method of the film 190 according to the embodiment includes the steps of forming a polymer resin into an elastic sheet, and passing the assembly in which the elastic sheet 80 is disposed on the carrier film 92 between rollers to form the elastic layer 100.

[0392] If the film 190 further includes additional layers such as adhesive layers 130, 130', hardening layer 120, and / or polarizing layer 360 in addition to the elastic layer 100, the manufacturing method of the film 190 may further include a step of laminating the elastic layer 100 and the additional layers.

[0393] The polymer resin may be an elastomer that forms amide residues as repeating units. The polymer resin may be an elastic polyamide resin or a polyether block amide resin. Examples of the elastic polyamide resin include PA11, PA12, PA1012, PA1010, PA610, and PA612. Examples of the polyether block amide resin include PEBAX® and Pebax® Rnew® from Arkema and VESTAMID® E from Evonik.

[0394] The polymer resin may be formed into an elastic sheet. The method for forming the elastic sheet may be any method applicable to the production of films, including melt extrusion. When the elastic layer or a film (or laminate) including the elastic layer is produced by the melt extrusion method, a high-quality elastic layer can be produced more efficiently.

[0395] When the polymer resin is melt-extruded to form an elastic sheet, the melt-extrusion temperature may be 200 to 300° C. When melt-extrusion is performed within this temperature range, the properties of the resin itself are not damaged, and fluidity is imparted to the polymer resin, allowing it to be smoothly formed into a sheet.

[0396] The elastic sheet 80 may be placed on a carrier film 92 .

[0397] The sheet laminate 90 including the carrier film and the elastic sheet disposed on the carrier film can be processed into a film-like elastic layer 100 by passing through rollers.

[0398] The rollers may be a first roll 40 and a second roll 60 that sandwich the sheet stack 90, and the first roll 40 may be a casting roll, and the second roll 60 may be a squeezing roll.

[0399] One side of the sheet stack is pressed against a casting roll, and the other side of the sheet stack is pressed against a squeezing roll, so that the sheet stack can be processed to a certain thickness.

[0400] During the processing, if necessary, the sheet laminate may further include a sheet protection film 94. Specifically, the sheet laminate may include a carrier film 92, an elastic sheet (or elastic layer) disposed on the carrier film, and a sheet protection film 94 disposed on the elastic sheet.

[0401] The method for manufacturing the elastic layer can be to manufacture an elastic sheet having a constant thickness and pass it between rollers to form an elastic layer having a predetermined thickness. The method for controlling the thickness of the elastic sheet and the method for controlling the thickness of the elastic layer while passing it between rollers can be applied as long as they are methods used in film manufacturing, and detailed descriptions will be omitted. Furthermore, a detailed description of the thickness of the elastic layer will be omitted as it overlaps with the above description.

[0402] The surface roughness of the elastic layer can be controlled during the process of passing between the rollers. The surface roughness of one side of the elastic layer can be controlled by the roughness of the carrier film that is in direct contact with the one side of the elastic layer. The surface roughness of the other side of the elastic layer can be controlled by the surface roughness of the squeezing roll or the surface roughness of the sheet protection film that is in direct contact with the other side of the elastic layer. Details regarding the surface roughness of the one and other sides of the elastic layer, the surface roughness of the carrier film, the surface roughness of the sheet protection film, the surface roughness of the squeezing roll, etc. are the same as those described above, so further description will be omitted.

[0403] In the method for manufacturing the film, the elastic layer may be manufactured in the form of an assembly together with a carrier film or the like, or the elastic layer itself from which the carrier film or the like has been removed.

[0404] The method for manufacturing the film may further include, if desired, removing the carrier film from the assembly.

[0405] The method for manufacturing the film may further include a step of disposing an adhesive layer on one or the other side of the elastic layer, if necessary.

[0406] The method for manufacturing the film may further include disposing a hardness layer on one side or the other side of the elastic layer, if necessary. The hardness layer may be a polyimide layer or a glass layer.

[0407] The hardness layer may be adhered to the elastic layer directly or via a separately disposed adhesive layer.

[0408] The method for manufacturing the film may further include a hard coating layer disposed on one or both sides of the elastic layer. The process for forming the hard coating layer may be any method for forming a hard coating layer on a protective film for a display.

[0409] The method for manufacturing the film may further include a polarizing plate disposed on one or the other side of the elastic layer. An adhesive layer, a hardening layer, or both the adhesive layer and the hardening layer may be disposed between the elastic layer and the polarizing plate.

[0410] A specific description of the film, the elastic layer, their uses, etc. will be omitted as they overlap with the above description.

[0411] The present invention will be described in more detail with reference to the following examples, which are merely illustrative and are not intended to limit the scope of the present invention.

[0412] Example: Fabrication of elastic layer and evaluation of physical properties Preparation of polymer resin The resins used in the examples and comparative examples of films including an elastic layer were prepared as follows.

[0413] - PEBA (polyether block amide) resin Arkema Pebax® 2533 (PEBA resin 1), Arkema Pebax® 5533 (PEBA resin 2), Arkema Pebax® 7033 (PEBA resin 3), Arkema Pebax® Rnew® 55R53 (PEBA resin 4), Arkema Pebax® Rnew® 63R53 (PEBA resin 5), Arkema Pebax® Rnew® 70R53 (PEBA resin 6), Arkema Pebax® Rnew® 72R53 (PEBA resin 7), Arkema Pebax® Rnew® 80R53 (PEBA resin 8), etc. were obtained from Arkema France and used in the following experiments.

[0414] - PA (Polyamide) resin PA610 (PA resin 1), PA612 (PA resin 2), PA1010 (PA resin 3), PA1012 (PA resin 4), PA12 (PA resin 5), AESNO TL (PA resin 6), PA11 (PA resin 7), etc. were obtained from Arkema France and used in the following experiments.

[0415] - TPU film, PET film The TPU used was Argotec's 46510 film (aliphatic TPU), and the PET film used was SKC's PET film NRF.

[0416] Manufacturing the elastic layer The prepared resins were placed in an extruder and melt-mixed, followed by extrusion into a single-layer elastic sheet. The melt-mixing temperature was adjusted within a range of approximately 200-300°C depending on the resin, with approximately 220°C applied for PEBA resin 7. The resulting single-layer elastic sheet was then placed on a carrier film (a PET film with a thickness of 50 μm to 250 μm, with an Ra of 0.001-0.01 μm) in a continuous process to form an assembly. This assembly was then passed between a casting roll and a squeezing roll heated to a temperature of 10-120°C to produce a laminate including an elastic layer. The carrier film was then removed, leaving an approximately 100 μm-thick elastic layer, which was referred to as the film of the example below, and its physical properties were evaluated. Each film was presented with the same name as the resin.

[0417] A film prepared in the same manner and with the same thickness without using a carrier film was used as a comparative film, and its physical properties were evaluated as follows.

[0418] Example: Evaluation of the physical properties of the elastic layer Evaluation of low-temperature damage index of elastic layer Tensile strength, elongation, etc. were measured using an Instron universal testing machine (UTM) according to standard ASTM D882 at a travel speed of 50 mm / min. A temperature control chamber was connected to the universal testing machine, and measurements were performed at +20°C, -10°C, and -40°C, respectively. The measured tensile strength, elongation, tensile modulus, etc. are shown in Table 1 below.

[0419] The low-temperature damage index was evaluated for film samples of PEBA resin 5 and PEBA resin 6, and as comparative examples, the PET film and TPU film prepared above were also evaluated.

[0420] [Table 1]

[0421] *The low-temperature damage index (MPa) is the value obtained by subtracting the tensile strength (MPa) from the tensile modulus (MPa) measured at low temperatures (e.g., temperatures below -10°C).

[0422] *Difference in low temperature tensile modulus TM -40-20 is expressed by the following formula:

[0423] [formula] JPEG0007825346000015.jpg656

[0424] In the above formula, TM -40-20 is the low-temperature tensile modulus difference, TM n is the tensile modulus measured at n°C.

[0425] Referring to Table 1, the PEBA film exhibits excellent elongation across the entire temperature range and a low tensile modulus at low temperatures, indicating less cracking at low temperatures compared to PET and TPU. Furthermore, the low-temperature damage index, which indicates the difference between tensile strength and tensile modulus, for the PEBA film is 1300 MPa or less at both -10°C and -40°C, indicating very little damage at both high and low temperatures. The PET films all exhibited high values ​​exceeding 4000 MPa, indicating that cracking occurs easily at low temperatures. The TPU films exhibited relatively high values ​​at low temperatures, which distinguishes them from the Examples.

[0426] Evaluation of storage modulus of elastic layer The storage modulus (E') was evaluated using a TA Instruments DMA Q800 model in accordance with ASTM D4065. The device was used in dynamic mechanical analysis (DMA) tension mode at 1 Hz and 2°C / min, and the storage modulus (E') was measured in MPa over the temperature range (-40 to +80°C). The results are shown in Table 2. The applied amplitude was 5 μm, and the applied preforce was 0.01 N.

[0427] The storage modulus of a PET film and a TPU film was evaluated at the same temperatures as above. The PET film was a 50 μm thick NRF film manufactured by SKC, and the TPU film was 46510 (a 100 μm thick monolayer film) manufactured by Argotec.

[0428] All sample films were conditioned in an atmosphere of 23°C and 50% RH for 15 days before being subjected to the above evaluation.

[0429] [Table 2] JPEG0007825346000017.jpg8151

[0430] *Storage modulus index K SM is expressed by the following formula 1.

[0431] [Formula 1] JPEG0007825346000018.jpg1163

[0432] **Ratio of high temperature storage modulus R 80 / 20 is expressed by the following formula 1-a.

[0433] [Formula 1-a] JPEG0007825346000019.jpg1134

[0434] **Ratio of low temperature storage modulus R -40 / 20 is expressed by the following formula 1-b.

[0435] [Formula 1-b] JPEG0007825346000020.jpg1139

[0436] ***The difference in low-temperature storage modulus is expressed by the following formula 1-c.

[0437] [Formula 1-c] JPEG0007825346000021.jpg651

[0438] In the above formula, SM n is the storage modulus (Mpa) measured at a temperature of n°C.

[0439] Measurement of surface roughness, yellowness, discoloration, etc. of elastic layer The surface roughness was evaluated using a MITUTOYO SJ-310 model in accordance with ASTM D4417.

[0440] Haze was measured using Nippon Denshoku's NDH-7000N haze meter in accordance with ISO 14782. Light transmittance was also measured using the same equipment, and it was confirmed that all samples had a light transmittance of 85% or more.

[0441] The YI (Yellow Index) was measured using a Hunterlab Color Meter Ultrascan Pro in YI E313 (D65 / 10) mode. A measured value of 1 or less was evaluated as Pass, and a value of more than 1 was evaluated as Fail.

[0442] Delta-YI was measured before and after 72 hours of UV exposure using a UVB Lamp (G15T8E, manufactured by Sankyo Denki, wavelength 280-360 nm) at an output of 3.0 W, and the value obtained by subtracting the YI before exposure from the YI after exposure was displayed.

[0443] [Table 3]

[0444] Elastic layer recovery force and dynamic bending evaluation An 80mm x 25mm film was fixed to a jig at 15mm from each end of the film, and the length of the film to which stress was applied was set to 50mm x 25mm. The film was stretched 2% at a rate of 50mm / min and then restored to its original length at a rate of 50mm / min, and a tensile test was performed after 100 cycles. The film's jig length (Xf) after 100 cycles was measured and compared to the initial film jig length (Xo, 50mm), and the recovery index was evaluated using the following equation 3.

[0445] [Formula 3] JPEG0007825346000023.jpg1245

[0446] In the formula 3, Xo is the initial length of the elastic layer (mm); X 2% is the length (mm) of the elastic layer after it has been stretched by 2%, Xf is the length (mm) of the elastic layer after 100 cycles, where one cycle is stretched by 2% at a speed of 50 mm / min and then restored to its original length at a speed of 50 mm / min.

[0447] Dynamic bending evaluation was performed according to the IEC 62715-6-1 standard. The film was subjected to a dynamic bending test at -40°C with a 2 mm radius of curvature and bending for 2 seconds per bending, after which the presence or absence of cracks was checked. If cracks were observed, the test was rated as Fail, and if no cracks were observed visually, the test was rated as Pass.

[0448] [Table 4]

[0449] Referring to Tables 2 to 4, the prepared elastic layers all exhibited lower haze values ​​compared to the elastic layers of the comparative examples, which is believed to be related to the surface roughness values ​​to some extent.

[0450] Delta-YI showed far superior results in the examples using PA or PEBA compared to other resins. In particular, the results of the examples were superior to those of Other Resin 1, which was a PET film, but also far superior to those of Other Resin 2, which used TPU. Furthermore, considering that the TPU used as the other resin was an aliphatic TPU, which is known to have better UV resistance than aromatic TPU, the films of the examples were evaluated to have far superior UV resistance.

[0451] In the dynamic bending evaluation conducted at -40°C, both Other Resin 1 and Other Resin 2 were rated as fail, confirming that films of other resins have insufficient properties for use in bending or folding applications over a wide temperature range, including low temperatures.

[0452] In the case of recovery index, although there was some variation in physical properties depending on the resin used, the examples using PEBA film or PA film generally showed excellent results, with the PEBA film showing even better results than the PA film.

[0453] The recovery index of the film of the example was slightly inferior to or at the same level as the films of other resin 2 to which TPU film was applied. On the other hand, the results of the UV resistance (yellowing characteristics) and dynamic bending test at low temperatures showed that the film of the example was far superior to the TPU film.

[0454] Considering these characteristics, the elastic layer or a film including the elastic layer of the embodiment is believed to be highly applicable to foldable displays, etc., which undergo repeated bending or folding over a wide temperature range from low to high.

[0455] Measurement of refractive index and phase difference of elastic layer The refractive index was measured using the DR-A1-plus model manufactured by ATAGO at a temperature of 23 degrees Celsius and a wavelength of 550 nm.

[0456] The in-plane retardation and the retardation in the thickness direction were measured using Otsuka Electronics' RETS-100 at a wavelength of 550 nm.

[0457] For refractive index, the following polymer resins were used and tested in the same manner as above. The names of the resins used to manufacture each sample are listed in Table 5, and in the case of PA resins, the degree of crystallinity is also listed.

[0458] For the in-plane retardation, samples with different thicknesses were separately manufactured and tested, and the results are shown in Table 6. For the comparative sample, the same as above was applied.

[0459] All resins were supplied by Arkema France and used.

[0460] [Table 5]

[0461] [Table 6]

[0462] Referring to Tables 5 and 6, it was confirmed that the refractive index was at an appropriate level as intended, and the retardation was also at an appropriate level for use in optical applications.

[0463] Example: Film production and evaluation of physical properties Film preparation Preparation of cover film test piece: A 100 μm thick adhesive layer of commercially available OCA from 3M (with a storage modulus measured at -40°C and a storage modulus measured at +80°C of -100 to +100 kPa) was used on a 50 μm thick transparent polyimide film (manufactured by SKC Corporation), and the 100 μm thick elastic layer (film made from PEBA resin 7) prepared above was laminated on the adhesive layer to prepare a cover film test piece of Example 1 (structure (b) in Figure 2).

[0464] Cover film specimens were prepared in the same manner as in Example 1, but with the type of elastic layer as shown in Table 8 below. These specimens were designated as Example 2 and Comparative Example 1, respectively.

[0465] Measurement of film properties 1) Evaluation of tensile impact strength The tensile impact strength of the elastic layer was evaluated in accordance with JIS K 7160. The impact strength and absorbed energy were measured at a temperature of 23°C, 50% RH, with a 4.0 J pendulum and a resonance angle of 150°, and the results are shown in Table 7 below.

[0466] 2) Bending / pen drop evaluation of laminated film Dynamic bending test: A protective film test piece was subjected to a bending test in accordance with IEC 62715-6-1, with a radius of curvature of 2 mm and a bending rate of 2 seconds per cycle, for a total of 200,000 cycles. If lifting occurred, the test was marked with an X, and if no lifting occurred, the test was marked with an O. The results are shown in Table 8 below.

[0467] Static bending test: A test was performed using a protective film specimen with a curvature radius of 2 mm according to IEC 62715-6-1. If lifting occurred after 24 hours, it was marked with an X, and if no lifting occurred, it was marked with an O. The results are shown in Table 8 below.

[0468] Pen drop evaluation: A ballpoint pen (BIC®) weighing approximately 5.4 g was dropped onto a laminate film sample from a height of 9 cm from the tip of the cap to the surface. If the film surface condition was good, it was evaluated as pass, and if cracks occurred on the film surface, it was evaluated as fail. The results are shown in Table 8 below.

[0469] Light transmittance / Haze: Light transmittance (transmittance) and haze were measured using an NDH7000 (manufactured by Nippon Denshoku Industries Co., Ltd.). A haze of 1% or less was rated as Pass, and a haze of more than 1% was rated as Fail. Light transmittance was rated as Pass when the transmittance for visible light was 90% or more, and as Fail when it was less than 90%. The results are shown in Table 8 below.

[0470] [Table 7]

[0471] [Table 8]

[0472] Referring to Table 7, the impact strength of the film of the example using PEBA resin 7 was shown to be much higher than the impact strength of the film using other resin 2 (TPU) and the film using other resin 1 (PET), confirming that it has very strong impact resistance. In terms of absorbed energy, the film of the example using PEBA resin 7 was also much better than the film using other resin 2 (TPU) and the film using other resin 1 (PET).

[0473] This indicates that TPU is superior to PET in terms of storage modulus, but inferior to PET in terms of tensile impact strength.The results also indicate that films using PEBA are superior in both storage modulus and tensile impact strength.

[0474] Referring to Table 8, the laminate of Example 1, which used the prepared PEBA resin 7, was rated "Pass" in all aspects of the dynamic bending test at low and high temperatures, the static bending test at low and high temperatures, the pen drop test, light transmittance, and haze, indicating excellent physical properties. In contrast, Example 2, which used the same adhesive layer and PI film as Example 1 but employed TPU instead of PEBA resin 7, was rated "Fail" in the dynamic bending test at low temperatures, indicating that lifting may occur during repeated bending at low temperatures. In contrast, Comparative Example 1, which used PET, was rated "Fail" in both the dynamic and static bending tests, indicating that the laminate has physical properties that make it difficult to use as a bendable or rollable cover film. Comparative Example 1, which uses a polyimide film alone, was rated "Fail" in the pen drop test, indicating that a polyimide film alone is insufficient to provide impact protection as a cover film.

[0475] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the appended claims also fall within the scope of the present invention. [Explanation of symbols]

[0476] 100 Elastic layer 100a One side of the elastic layer 100b Other surface of elastic layer 120 hardness layer 130,130' adhesive layer 140 Hard coating layer 150 Release Film 80 Elastic Sheet 92 Carrier Film 94 Sheet protection film 40 1st roll, casting roll 60 Second roll, squeezing roll 90 Sheet stack 190 Films, film laminates 300 Light-emitting functional layer 320 Light-emitting layer 322 Signaling Layer 324 Coloring layer 326 Sealing Layer 340 Sensor Layer 360 polarizing layer 380 Supporter layer 900 Multi-layered Electronic Equipment

Claims

1. A monolayer film comprising an elastic layer containing a polyether block amide resin, the elastic layer has a refractive index of 1.48 to 1.58; The low-temperature damage index of the elastic layer is the difference between the tensile modulus and the tensile strength at a specific temperature, the elastic layer has a low-temperature damage index of 300 MPa or more and 1,300 MPa or less at −40° C.; The tensile modulus at -40°C is 500 MPa or more and 2,000 MPa or less, The recovery force index represented by the following formula 3 is 60 or more and 90 or less, the roughness reference value of the elastic layer is the larger value of Ra1, which is the value of the arithmetic mean roughness Ra of one surface, and Ra2, which is the value of the arithmetic mean roughness Ra of the other surface; The elastic layer is a single-layer film having a roughness reference value of 0.001 μm or more and 0.1 μm or less. [Formula 3] (In the above formula 3, Xo is the initial length of the elastic layer (mm); X 2% is the length (mm) of the elastic layer after it has been stretched by 2%; Xf is the length (mm) of the elastic layer after 100 cycles, where one cycle is a cycle of pulling 2% at a speed of 50 mm / min and then restoring to the original length at a speed of 50 mm / min, The arithmetic mean roughness is evaluated in accordance with ASTM D4417, and the tensile modulus and tensile strength are measured in accordance with ASTM D882 at a moving speed of 50 mm / min.

2. The monolayer film according to claim 1, wherein the elastic layer has a tensile modulus of elasticity at -10°C of 350 MPa or more and 3,000 MPa or less.

3. The monolayer film according to claim 1 , wherein the elastic layer has an in-plane retardation Re of 300 nm or less.

4. The monolayer film according to claim 1, wherein the elastic layer has a storage modulus at -40°C of 200 MPa or more and 2300 MPa or less.

5. The monolayer film according to claim 1, wherein the elastic layer has an elongation of 200% or more and 400% or less at -10°C. (The elongation is measured according to ASTM D882 at a moving speed of 50 mm / min.)

6. A monolayer film according to claim 1, and a hardness layer disposed on one surface of the monolayer film, the refractive index of the elastic layer is smaller than the refractive index of the hardness layer, a difference between the refractive index of the elastic layer and the refractive index of the hard layer is 0.2 or less; the hardness layer comprises a polyimide film or a glass layer; A laminated film having a total thickness of 3,000 μm or less.

7. 7. The laminated film according to claim 6, wherein the elastic layer has a light transmittance of 85% or more and a haze of 3% or less.

8. A light-transmitting laminate comprising the monolayer film according to claim 1 or the laminate film according to claim 6.

9. forming an elastic sheet from a polymeric resin containing an amide or residue thereof as a repeating unit; and passing a first assembly in which the elastic sheet is disposed on a carrier film between rollers to provide a second assembly including an elastic layer disposed on the carrier film, A method for producing a film, comprising producing the monolayer film according to claim 1 or the laminate film according to claim 6.

10. A cover film comprising the monolayer film of claim 1 or the laminate film of claim 6.

11. The elastic layer may further include a glass layer disposed on one side or the other side of the elastic layer. The cover film according to claim 10 , wherein the glass layer is tempered glass having a thickness of 200 μm or less.

12. The light-emitting functional layer and the film are included. the light-emitting functional layer has a display area that emits or does not emit light according to an external signal; The film is the monolayer film according to claim 1 or the laminate film according to claim 6, The film is disposed on the top or back surface of the display area, a multi-layer electronic device.

13. The light-emitting functional layer and the film are included. the light-emitting functional layer has a display area that emits or does not emit light according to an external signal; The film is the monolayer film according to claim 1 or the laminate film according to claim 6, The film is disposed on one surface of the light-emitting functional layer and covers at least a part of the display area.

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