Laminate film having improved surface hardness and recovery performance and display device comprising the same

Abstract

In the laminate film according to the embodiment, the elastic layer containing a polyether block amide is laminated with a base film treated with a hard coat. Due to the layer structure of the composite of different materials, it is possible to simultaneously improve the surface hardness, the recovery performance and the elasticity, and also to achieve excellent optical performance.

Description

Technical Field

[0001] The present invention relates to a laminate with enhanced surface hardness and recoverability, and a display device comprising the laminate. Background Technology

[0002] Driven by the development of IT equipment and market demand, display technology continues to advance. Curved screen display technology has been commercialized. In recent years, flexible display devices that can be flexibly bent or folded to withstand external forces have gained favor in the field of mobile devices that require large screens and portability. In particular, foldable display devices have significant advantages, as they can be folded into a smaller size to enhance portability when not in use, and unfolded to form a larger screen when in use.

[0003] The cover window of this flexible display device needs to be flexible and recoverable. Furthermore, in outward-folding types where the display is exposed to the outside, it not only needs to be flexible but also needs to have protective properties against external forces.

[0004] Display devices primarily use polymer films (such as transparent polyimide or polyester) or glass substrates as their cover windows. However, polymer films are easily affected by external scratches, while glass substrates suffer from insufficient flexibility.

[0005] To address this issue, Korean Patent Publication No. 2019-0026611 discloses a hard coating film manufactured by sequentially forming a high-bending layer and a high-hardness layer on a transparent substrate using siloxane resin, thereby enhancing scratch resistance and flexibility.

[0006] Existing technical documents

[0007] (Patent Document 1) Korean Patent Publication No. 2019-0026611. Summary of the Invention

[0008] Technical issues

[0009] To date, films developed for display overlay windows have limitations in achieving a balance between surface hardness and recoverability or elasticity. Furthermore, when a hard coating is formed to enhance surface hardness, there is a problem that flexibility or recoverability deteriorates significantly, or the film's optical properties worsen.

[0010] Through research conducted by the inventors, it has been discovered that when an elastic layer containing polyether block amide is laminated with a base film treated with a hard coating, not only can the surface hardness and recoverability or elasticity be enhanced, but also excellent optical properties can be achieved.

[0011] Therefore, the embodiments described below are intended to provide a laminate with enhanced surface hardness and recoverability or elasticity as well as excellent optical properties, and a display device comprising the laminate.

[0012] Solution to the problem

[0013] According to one embodiment, the present invention provides a laminated film comprising: a base film; a rigid coating disposed on one side of the base film; and an elastic layer disposed on the other side of the base film, wherein the elastic layer comprises a polyether block amide.

[0014] According to another embodiment, the present invention provides a display device comprising: a display panel; and a cover window disposed on the front side of the display panel, wherein the cover window comprises a base film; a rigid coating disposed on one side of the base film; and an elastic layer disposed on the other side of the base film, wherein the elastic layer comprises polyether block amide.

[0015] Beneficial effects of the invention

[0016] According to one embodiment, the laminated film comprises an elastic layer containing polyether block amide and a base film treated with a hard coating; therefore, through the layer structure of different material combinations, not only can the surface hardness and recoverability or elasticity be enhanced, but also excellent optical performance can be achieved.

[0017] Therefore, when the laminate according to the embodiment is applied to the cover window of a flexible display device, such as the cover window of an outward-folding device (in which the display screen is exposed to the outside) or an inward-folding device, the laminate can have the property of protecting the display screen from external forces, while having flexible characteristics, and its optical performance can also be excellent. Attached Figure Description

[0018] Figure 1 An exploded perspective view of a display device according to one embodiment is shown.

[0019] Figure 2 A cross-sectional view of a laminated film according to one embodiment is shown. Figure 1 (A-A' in the middle).

[0020] Figure 3 The images show the conditions before (a) and after (b) in the nanoindentation test.

[0021] Figure 4 Cross-sectional views of the sample are shown when the indenter tip is pressed in (a) and released (b).

[0022] Figure 5a and 5b The inward-folding and outward-folding flexible display devices are shown respectively.

[0023] <Explanation of Figure Markers>

[0024] 1: Display device

[0025] 1a: Inward-folding flexible display device

[0026] 1b: Outward-folding flexible display device

[0027] 2: Indenter; 2a: Tip of the indenter; 2b: Mark (dent) left after releasing the indentation.

[0028] 10: Laminated film (covering window); 10a: Sample; 20: Display panel

[0029] 30: Circuit board; 40: Frame; 100: Base film; 200: Hard coating; 300: Elastic layer

[0030] A p Contact projection area; F: Test force; F max Maximum test force;

[0031] h max Maximum indentation depth under maximum test force

[0032] h p Indentation depth after releasing test force

[0033] Best Implementation of the Invention

[0034] Various implementation schemes and examples will be described in detail below with reference to the accompanying drawings.

[0035] In the following description of the embodiments, detailed descriptions of relevant known components or functions will be omitted if they would obscure the subject matter. Furthermore, the sizes of the various elements in the accompanying drawings may be exaggerated or omitted for ease of description, and these elements may differ from their actual sizes.

[0036] In this specification, when describing a component forming on / under another component or being connected or coupled to each other, it covers situations where these components are formed, connected, or coupled directly or indirectly through another component. Furthermore, it should be understood that references to the upper / lower positions of the various components may vary depending on the orientation of the object being observed.

[0037] In this specification, the terms used to refer to the various components are for the purpose of distinguishing them from each other and are not intended to limit the scope of the embodiments. Furthermore, in this specification, unless the context otherwise requires, singular expressions are also construed as encompassing plural expressions.

[0038] In this specification, the term "comprising" is intended to specify a particular characteristic, region, step, process, element, and / or component. This term does not exclude the presence or addition of any other characteristic, region, step, process, element, and / or component unless expressly stated to the contrary.

[0039] In this specification, the terms first, second, etc., are used to describe various components. However, these components should not be limited by these terms. The use of terms is intended to distinguish one element from another.

[0040] The molecular weights of the compounds or polymers described in this specification, such as number-average molecular weight or weight-average molecular weight, are based on the relative mass of carbon-12, as is well known. Although their units are not described, they can be understood as equivalent molar masses (g / mol) if necessary.

[0041] Figure 1 An exploded perspective view of a display device according to one embodiment is shown. Figure 2 A cross-sectional view of a laminated film (covering window) according to one embodiment is shown. Figure 1 (A-A' in the middle).

[0042] refer to Figure 2 According to one embodiment, the laminate (10) comprises: a base film (100); a hard coating (200) disposed on one side of the base film (100); and an elastic layer (300) disposed on the other side of the base film, wherein the elastic layer (300) comprises polyether block amide.

[0043] According to one embodiment, the laminated film comprises an elastic layer containing polyether block amide and a base film treated with a hard coating; therefore, through the layer structure of different material combinations, not only can the surface hardness and recoverability or elasticity be enhanced, but also excellent optical performance can be achieved.

[0044] Surface hardness of laminate

[0045] The surface hardness of laminated films can be measured using nanoindentation testing.

[0046] Nanoindentation is an analytical technique that involves applying a small force (load) on the material surface at the level of μN to mN using an indenter with a specific geometry, and then releasing it to obtain a force-displacement curve. This curve is then analyzed to measure various mechanical properties, such as tensile properties, residual stress, hardness, and elastic modulus.

[0047] The tip of the indenter can have a variety of geometries. For example, it can be conical, pyramidal, or triangular pyramidal (Berkovich triangular pyramidal or Vickers triangular pyramidal) or cylindrical flat punch shape.

[0048] Figure 3The images show the sample before (a) and after (b) in a nanoindentation test.

[0049] Figure 4 Cross-sectional views of the sample are shown when the indenter tip is pressed in (a) and released (b).

[0050] refer to Figure 3 and Figure 4 Because common polymer materials are viscoelastic, when the sample (10a) is pressed in by the tip (2a) at the lower end of the indenter (2), it will deform to the maximum depth (h) under the maximum test force. max Subsequently, when the indenter (2) is removed to release the indentation at the tip (2a), due to the elasticity of the polymer, some of the deformation recovers, while the remaining portion cannot permanently recover, leaving a mark of a certain depth (h). p The indentation (2b).

[0051] In this nanoindentation test, stiffness (S) and contact projected area (A) were measured. p ), test force (F), maximum indentation depth (h) under maximum force max ), and obtain force-displacement curves. Based on these results, the indentation modulus (E) can be calculated. IT ), indentation hardness (H) IT Vickers hardness (H) V Martens hardness (H) M Indentation creep (C) IT ), restoration relationship (η) IT Nanoindentation testing can be performed according to ISO 14577-1:2002(E) standard.

[0052] Martens hardness (HM), also known as composite hardness, is calculated based on the indentation depth when a test force is applied. Unlike indentation hardness, it provides information about the plasticity and elasticity of the material. A laminate according to one embodiment can have, for example, 250 N / mm². 2 Or higher, 260N / mm 2 Or higher, 270 N / mm 2 Or higher, or 275 N / mm 2 Or higher, and 400 N / mm 2 Or lower, 350 N / mm 2 Or lower, 330N / mm 2 Or lower, 310 N / mm 2 Or lower, or 290 N / mm 2Or even lower martensitic hardness. As a specific example, when the martensitic hardness (HM) of a hard coating surface is measured by nanoindentation testing according to ISO 14577-1:2002(E) standard, the laminate's martensitic hardness (HM) can be 250 N / mm². 2 Or higher, more specifically, 250 N / mm 2 Up to 350 N / mm 2 .

[0053] Vickers hardness (HV) is measured by indentation hardness (H IT Multiply by 0.0945 (H) IT The value is calculated as ×0.0945 and can be measured according to, for example, ISO 14577-1:2002(E) standard. Plastic properties such as ductility, malleability, and impact resistance can be obtained from the Vickers hardness (HV). A laminate according to one embodiment can have, for example, 40 N / mm². 2 Or higher, 45 N / mm 2 Or higher, 48 N / mm 2 Or higher, or 49 N / mm 2 Or higher, and 60 N / mm 2 Or lower, 55 N / mm 2 Or lower, or 53 N / mm 2 Or even lower Vickers hardness (HV). As a specific example, when the Vickers hardness (HV) of a hard coating surface is measured by nanoindentation testing according to ISO 14577-1:2002(E), the laminate can have a Vickers hardness (HV) of 48 N / mm². 2 Or higher, more specifically, 48 N / mm 2 Up to 55 N / mm 2 .

[0054] The high Vickers hardness (HV) of the laminate according to one embodiment can be attributed to the hard coating. For example, the HV increase of the laminate (N / mm) can be calculated using the following equation. 2 It can be 1.5 N / mm 2 Or higher, specifically 2.0 N / mm 2 Or higher or 2.5 N / mm 2 Or higher, for a more specific example, 1.5 N / mm 2 Up to 7.0 N / mm 2 .

[0055] HV increase (N / mm) 2 =HV1 (N / mm) 2 )-HV2(N / mm 2 )

[0056] Here, HV1 is the Vickers hardness (HV) of the laminate (N / mm²).2 HV2 is the Vickers hardness (HV) (N / mm²) of a laminated film with a hard coating removed. 2 ).

[0057] Indentation hardness (H) IT Also known as ductile hardness, it is a measure of a material's resistance to permanent (plastic) deformation under maximum force. Plastic properties such as ductility, malleability, and impact resistance can be obtained from it. Specifically, indentation hardness (H... IT ) is based on the maximum test force (F) max Divide by the contact projection area at the penetration depth (A) p The value of (F) max / A p This is calculated. According to one embodiment, the laminate can have, for example, 500 N / mm². 2 Or higher, 505 N / mm 2 Or higher, 510 N / mm 2 Or higher, 515 N / mm 2 Or higher, 520N / mm 2 Or higher, or 524 N / mm 2 Or higher, and 550 N / mm 2 Or lower, 545 N / mm 2 Or lower, 540 N / mm 2 Or lower, or 535 N / mm 2 Or lower indentation hardness (H) IT As a specific example, when the surface of a hard coating is measured by nanoindentation testing according to ISO 14577-1:2002(E) standard, the indentation hardness (H) of the laminate is... IT It can be 505 N / mm 2 Or higher, more specifically, 505 N / mm 2 Up to 550 N / mm 2 In the above indentation hardness (H) IT Within a certain range, its plastic properties, such as impact resistance, are manifested, making it suitable for use as a cover window for display devices.

[0058] The high pressure indentation hardness (H) of the laminate according to one embodiment IT This can be attributed to a hard coating. For example, the H of the laminate can be calculated using the following equation. IT Increase (N / mm) 2 It can be 10 N / mm 2 Or higher, specifically 15 N / mm 2 Or higher, 20N / mm 2 Or higher, or 25 N / mm 2 For a more specific example, it is 10 N / mm.2 Up to 70 N / mm 2 .

[0059] H IT Increase (N / mm) 2 )=H IT 1 (N / mm) 2 )-H IT 2 (N / mm) 2 )

[0060] Here, H IT 1 is the indentation hardness (H) of the laminate. IT (N / mm) 2 ), H IT 2 is the indentation hardness (H) of a laminated film with a hard coating removed. IT (N / mm) 2 ).

[0061] Indentation modulus (E) IT The indentation modulus can be calculated using the Poisson's ratio of the sample and the indenter, the modulus of the indenter, and the reduction modulus of the indentation contact, which can be measured by nanoindentation testing according to, for example, ISO 14577-1:2002(E) standards. The indentation modulus (E...) IT This allows for the acquisition of elastic properties such as hardness and abrasion resistance. According to one embodiment, the indentation modulus (E) of the laminate is... IT The pressure can be, for example, 3600 MPa or higher, 3800 MPa or higher, 4000 MPa or higher, or 4200 MPa or higher, and 5000 MPa or lower, 4800 MPa or lower, 4600 MPa or lower, or 4500 MPa or lower. As a specific example, when measuring the surface of a hard coating using a nanoindentation test according to ISO 14577-1:2002(E) standard, the indentation modulus (E) of the laminate is... IT It can be 3800 MPa or higher, more specifically, 3800 MPa to 4800 MPa.

[0062] Indentation creep (C IT This describes the further deformation of a material under constant force. To measure indentation creep (C... IT This requires pressing the indenter onto the sample with a constant force for a relatively long period (minutes to hours). The indentation depth can be calculated by measuring the increase in indentation depth due to continuous pressure. The indentation creep (C) of the laminate according to one embodiment is also considered. ITThe percentage can be, for example, 3.0% or higher, 3.3% or higher, 3.5% or higher, 3.6% or higher, or 3.7% or higher, and 4.5% or lower, 4.3% or lower, 4.1% or lower, 4.0% or lower, or 3.9% or lower. As a specific example, when the surface of a hard coating is measured by nanoindentation testing according to ISO 14577-1:2002(E), the indentation creep (C) of the laminate is... IT It can be 3.3% or higher, more specifically, 3.3% to 4.2%.

[0063] Restoration relationship (η) IT This can be calculated as the elastically retained deformation work (W) elast ) and total mechanical work of indentation (W) total The percentage of W on the force-depth curve (i.e., W) elast / W total The force-depth curve (η) can be obtained by pressing an indenter into the sample surface and then releasing it. The recovery relationship can be measured according to, for example, ISO 14577-1:2002(E). The recovery relationship (η) of the laminate according to one embodiment... IT The percentage can be, for example, 60% or higher, 65% or higher, 68% or higher, or 70% or higher, and 85% or lower, 80% or lower, 78% or lower, or 75% or lower. As a specific example, when measuring a hard coating surface using a nanoindentation test according to ISO 14577-1:2002(E), the recovery relationship (η) of the laminate is... IT It can be 68% or higher, more specifically, 68% to 78%.

[0064] The recovery rate can be calculated from the value measured by the nanoindentation test using the following equation. The recovery rate of the laminate according to one embodiment can be, for example, 65% or higher, 70% or higher, 75% or higher, 76% or higher, or 78% or higher, and 95% or lower, 90% or lower, 85% or lower, or 83% or lower. As a specific example, when the hard coating surface is measured by the nanoindentation test according to ISO 14577-1:2002(E), the recovery rate of the laminate can be 76% or higher, more specifically, 76% to 90%. The recovery rate can be calculated using the following equation.

[0065] Recovery rate (%) = [(h max(30mN时) -h p ) / h max(30mN时) ]×100

[0066] Here, h max (At 30mN) is the maximum indentation depth (μm) achieved when a 30mN force is applied downwards to the hard coating surface for 15 seconds and held (creep) for 5 seconds.p It is the indentation depth (μm) that has not recovered even after the force is released.

[0067] The high recovery rate of the laminate according to one embodiment can be attributed to the rigid coating or the elastic layer. For example, the increase in the recovery rate (%) of the laminate can be 2% or higher, specifically 3% or higher or 5% or higher, and as a more specific example, 3% to 20%.

[0068] Recovery rate increase (%) = Recovery rate 1 (%) - Recovery rate 2 (%)

[0069] Here, recovery rate 1 is the recovery rate (%) of the laminated film, and recovery rate 2 is the recovery rate (%) of the film with the layer structure of either the hard coating or the elastic layer removed from the laminated film.

[0070] Optical properties of laminates

[0071] Laminated films can have light transmittance, for example, at least a certain level of average visible light transmittance. Therefore, they are suitable for use as cover windows in display devices. For example, laminated films can have an average visible light transmittance of 70% or higher, 75% or higher, 80% or higher, 82% or higher, 83% or higher, or 85% or higher. Meanwhile, the upper limit of the range of average visible light transmittance of the laminated film is not particularly limited. This upper limit can be, for example, 100% or lower, 95% or lower, or 90% or lower. Transmittance can be measured, for example, according to the ISO 13468 standard. As a specific example, when measured according to the ISO 13468 standard, the laminated film can have an average visible light transmittance of 80% or higher or 85% or higher.

[0072] Furthermore, the laminated film can have an increased transmittance effect due to the rigid coating. For example, the transmittance increase (%) of the laminated film can be 2% or higher, specifically 2.5% or higher, 3% or higher, 4% or higher, or 5% or higher, and as a more specific example, 2% to 10% or 3% to 10%.

[0073] Transmittance increase (%) = TT1 (%) - TT2 (%)

[0074] Here, TT1 is the average visible light transmittance (%) of the laminated film, and TT2 is the average visible light transmittance (%) of the film with the hard coating removed from the laminated film. The average visible light transmittance is measured under the same conditions according to ISO 13468 standard.

[0075] According to one implementation scheme, when measured according to ISO 13468 standard, the laminate can have an average visible light transmittance of 85% or higher, which, according to the above equation, represents a transmittance increase of 3% or higher.

[0076] Furthermore, the laminated film can have a haze level below a certain threshold. Therefore, it is suitable for use as a cover window for display devices. For example, the laminated film can have a haze of 5% or less, 4% or less, 3.5% or less, 3% or less, or 2% or less. Meanwhile, the lower limit of the haze range of the laminated film is not particularly limited. This lower limit can be, for example, 0% or more, 0.5% or more, or 1% or more. Haze can be measured, for example, according to the ISO 14782 standard. As a specific example, when measured according to the ISO 14782 standard, the laminated film can have a haze of 4% or less.

[0077] According to one implementation scheme, when measured according to ISO 13468 standard, the laminate can have an average visible light transmittance of 80% or higher, and when measured according to ISO 14782 standard, the laminate can have a haze of 4% or lower. According to the above equation, the transmittance increase is 2% or higher.

[0078] Furthermore, the laminate can have a yellow index below a certain level. Therefore, the image displayed on the screen can be recognized without distortion. For example, the laminate can have a yellow index of 2 or lower, 1.5 or lower, or 1 or lower. Meanwhile, the lower limit of the yellow index range for the laminate is not particularly limited. This lower limit can be 0 or higher, 0.3 or higher, 0.5 or higher, or 0.6 or higher. The yellow index (YI) can be measured using a spectrophotometer according to the ASTM-E313 standard, for example, using a D65 light source. As a specific example, when measured at 10° using a D65 light source according to the ASTM-E313 standard, the yellow index of the laminate can be 1.5 or lower.

[0079] Furthermore, the laminated film can have a yellowing index reduction effect due to the hard coating. For example, the yellowing index reduction of the laminated film can be 0.5 or higher, specifically 0.7 or higher or 1.0 or higher, and as a more specific example, 0.5 to 5.

[0080] Yellow Index Decrease (%) = YI2 - YI1

[0081] Here, YI1 is the yellow index of the laminated film, and YI2 is the yellow index of the film with the hard coating removed from the laminated film. The yellow index is measured at 10° using a D65 light source under the same conditions according to ASTM-E313 standard.

[0082] Furthermore, the color of the laminating film can be adjusted to a specific range. Therefore, the image displayed on the screen can be recognized without distortion. For example, the L* value of the transparent color of the laminating film in the CIE Lab color coordinate system can be 85 or higher, 90 or higher, or 93 or higher, and can be 100 or lower, 97 or lower, or 95 or lower. Similarly, the a* value of the transparent color of the laminating film in the CIE Lab color coordinate system can be -3 or higher, -2 or higher, -1.5 or higher, or -1 or higher, and 2 or lower, 1 or lower, 0 or lower, -0.5 or lower, or -0.9 or lower. For example, the b* value of the transparent color of the laminating film in the CIE Lab color coordinate system can be -2 or higher, -1 or higher, 0 or higher, or 0.5 or higher, and 3 or lower, 2 or lower, 1.5 or lower, or 1 or lower. The transparent color can be measured using a spectrophotometer, for example, using a D65 as the light source. As a specific example, when measured using a D65 light source, the L* value of the transparent color of the laminate in the CIE Lab color coordinates can be 92 or higher, the a* value can be -2 to 1, and the b* value can be -1 to 2.

[0083] Base film (100)

[0084] The base film (100) serves as the base layer of the primer layer (200) and also imparts mechanical properties to the laminate (10).

[0085] The base film can be a polymer film or a glass substrate, specifically a reinforced glass substrate with a thickness of less than about 100 μm. For example, the base film can comprise a polymer film or ultrathin glass (UTG).

[0086] Specifically, the base film can be a polymer film. That is, the base film can contain a polymer resin.

[0087] Examples of polymeric resins contained in the base film include polyester resins such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and polybutylene terephthalate; cellulose-based resins such as diacetylcellulose and triacetylcellulose; polycarbonate-based resins; acrylic resins such as poly(meth)acrylate and poly(meth)acrylate; styrene-based resins such as polystyrene and acrylonitrile-styrene copolymers; polyolefin resins such as polyethylene, polypropylene, polyolefins with cycloalkenes or norbornene structures, and ethylene-propylene copolymers; vinyl chloride resins; amide resins such as nylon and aromatic polyamides; imide-based resins; polyamide-imide-based resins; polyethersulfone resins; polyurethane resins; sulfone-based resins; polyetheretherketone-based resins; vulcanized polystyrene resins; vinyl alcohol-based resins; vinylidene chloride resins; vinyl butyral-based resins; allyl ester-based resins; polyoxymethylene-based resins; and epoxy-based resins. They can be used alone or in combination of two or more.

[0088] In addition to polymer resins, the base film may also contain fillers. For example, the base film may contain polyimide resins and fillers.

[0089] The filler can be at least one selected from the group consisting of barium sulfate, silica, and calcium carbonate. Because the base film contains filler, its roughness and rollability can be improved, as well as its sliding properties and scratch resistance during film preparation.

[0090] The particle size of the filler can be from 0.01 μm to less than 1.0 μm. For example, the particle size of the filler can be from 0.05 μm to 0.9 μm or from 0.1 μm to 0.8 μm, but is not limited thereto.

[0091] The amount of filler used can be from 0.01% to 3% by weight, depending on the total weight of the base membrane. For example, the amount of filler used can be from 0.05% to 2.5% by weight, 0.1% to 2% by weight, or 0.2% to 1.7% by weight, depending on the total weight of the base membrane, but is not limited thereto.

[0092] The thickness of the base film can be 20 μm or thicker, 30 μm or thicker, 40 μm or thicker, 50 μm or thicker, or 100 μm or thicker, and 500 μm or thinner, 400 μm or thinner, 300 μm or thinner, or 200 μm or thinner. As a specific example, the thickness of the base film can be from 20 μm to 500 μm, more specifically from 40 μm to 200 μm or from 50 μm to 200 μm.

[0093] The base film can have optical and mechanical properties that can be adjusted to a certain range.

[0094] The haze of the base film can be 3% or lower. For example, the haze of the base film can be 2% or lower, 1.5% or lower, or 1% or lower, but is not limited to these.

[0095] The yellowness index (YI) of the base film can be 5 or lower. For example, the yellowness index of the base film can be 4 or lower, 3.8 or lower, 2.8 or lower, 2.5 or lower, 2.3 or lower, or 2.1 or lower, but is not limited to these.

[0096] The modulus of the base film can be 5 GPa or higher. For example, the modulus of the base film can be 5.2 GPa or higher, 5.5 GPa or higher, 6.0 GPa or higher, 10 GPa or lower, 5 GPa to 10 GPa, or 7 GPa to 10 GPa, but is not limited to these.

[0097] The transmittance of the base film can be 80% or higher. For example, the transmittance of the base film can be 85% or higher, 88% or higher, 89% or higher, 80% to 99%, or 85% to 99%, but is not limited to these.

[0098] The compressive strength of the base film can be 0.4 kgf / μm or higher. Specifically, the compressive strength of the base film can be 0.45 kgf / μm or higher, or 0.46 kgf / μm or higher, but is not limited to these.

[0099] The surface hardness of the base film can be HB or higher. Specifically, the surface hardness of the base film can be H or higher, or 2H or higher, but is not limited to these.

[0100] The tensile strength of the base film can be 15 kgf / mm². 2 Or even higher. Specifically, the tensile strength of the base film can be 18 kgf / mm². 2 Or higher, 20 kgf / mm 2 Or higher, 21 kgf / mm 2 Or higher, or 22 kgf / mm 2 Or higher, but not limited to this.

[0101] The elongation of the base film can be 15% or higher. Specifically, the elongation of the base film can be 16% or higher, 17% or higher, or 17.5% or higher, but is not limited to these.

[0102] Polyimide resin

[0103] For example, the base film may comprise a polyimide-based resin. Specifically, the base film may be a transparent polyimide-based film. The polyimide-based resin can be prepared by reacting reactants comprising a diamine compound and a dianhydride compound simultaneously or sequentially. Specifically, the polyimide-based resin may comprise a polyimide-based polymer prepared by polymerizing a diamine compound and a dianhydride compound. The polyimide-based resin may comprise repeating imide units derived from the polymerization reaction of the diamine compound and the dianhydride compound. Furthermore, the polyimide-based resin may be polymerized by further comprising a dicarbonyl compound. Therefore, it may comprise a polyamide-imide-based polymer that also comprises repeating amide units derived from the polymerization reaction of the diamine compound and the dicarbonyl compound.

[0104] There are no particular limitations on the diamine compound, but it can be, for example, an aromatic diamine compound containing an aromatic structure. For example, the diamine compound can be a compound shown in Formula 1 below.

[0105] Formula 1

[0106] H2N-(E) e -NH2

[0107] In Equation 1, E is selected from substituted or unsubstituted divalent C6-C. 30 Aliphatic cyclic group, substituted or unsubstituted divalent C4-C 30 Heterocyclic cycloids, substituted or unsubstituted divalent C6-C 30Aromatic cycloyl groups, substituted or unsubstituted divalent C4-C 30 heterocyclic cycloids, substituted or unsubstituted C1-C 30 Alkylene, substituted or unsubstituted C2-C 30 alkenyl, substituted or unsubstituted C2-C 30 The following groups are used: -ynyne, -C(=O)-, -CH(OH)-, -S(=O)2-, -Si(CH3)2-, -C(CH3)2-, and -C(CF3)2-. e is an integer selected from 1 to 5. When e is 2 or more, E can be the same or different from each other.

[0108] In this specification, the term "substitution" refers to a C1-C group selected from deuterium, -F, -Cl, -Br, -I, hydroxyl, cyano, nitro, amino, amide, hydrazine, hydrazone, ester, ketone, carboxyl, substituted or unsubstituted. 30 Alkyl, substituted or unsubstituted C2-C 30 alkenyl, substituted or unsubstituted C2-C 30 Alkyne, substituted or unsubstituted C1-C 30 Alkoxy, substituted or unsubstituted C6-C 30 Alicyclic organogroups, substituted or unsubstituted C4-C 30 Heterocyclic groups, substituted or unsubstituted C6-C 30 Aryl and substituted or unsubstituted C4-C 30 It is substituted by at least one substituent of the group consisting of heteroaryl groups. Two adjacent substituents may be linked to form a ring.

[0109] In Equation 1, (E) e It may be selected from the groups shown in formulas 1-1a to 1-14a below, but is not limited thereto.

[0110]

[0111] Specifically, (E) in Formula 1 e It may be selected from the groups shown in formulas 1-1b to 1-13b below, but is not limited thereto.

[0112]

[0113] More specifically, (E) in Equation 1 above e It can be the group shown in Formula 1-6b above.

[0114] In one embodiment, the diamine compound may comprise a compound having a fluorinated substituent. Alternatively, the diamine compound may consist of a compound having a fluorinated substituent. In this case, the fluorinated substituent may be a fluorinated hydrocarbon group, specifically a trifluoromethyl group. However, it is not limited thereto.

[0115] In one embodiment, a diamine compound can be used as the diamine compound. That is, the diamine compound can consist of a single component.

[0116] For example, diamine compounds may contain, but are not limited to, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) as shown in the formula below.

[0117]

[0118] Diacid anhydride compounds have low birefringence values, which can help improve the optical properties of films containing polyimide resins, such as light transmittance.

[0119] There are no particular restrictions on the dianhydride compounds, but they can be aromatic dianhydride compounds containing aromatic structures. For example, an aromatic dianhydride compound can be a compound shown in Formula 2 below.

[0120] Formula 2

[0121]

[0122] In Equation 2, G can be selected from substituted or unsubstituted tetravalent C6-C. 30 Aliphatic cyclic group, substituted or unsubstituted tetravalent C4-C 30 Heterocyclic aliphatic cycloid, substituted or unsubstituted tetravalent C6-C 30 Aromatic cycloalloys, substituted or unsubstituted, tetravalent C4-C 30 The group consisting of aliphatic, heteroaliphatic, aromatic, or heteroaromatic cyclic groups can exist alone, can fuse together to form a fused ring, or can be derived from substituted or unsubstituted C1-C groups. 30 Alkylene, substituted or unsubstituted C2-C 30 alkenyl, substituted or unsubstituted C2-C 30 Linking groups include alkynyl, -O-, -S-, -C(=O)-, -CH(OH)-, -S(=O)2-, -Si(CH3)2-, -C(CH3)2- and -C(CF3)2-.

[0123] In Formula 2 above, G can be selected from the groups shown in Formulas 2-1a to 2-9a below, but is not limited thereto.

[0124]

[0125] For example, G in Formula 2 above can be the group shown in Formula 2-8a above.

[0126] In one embodiment, the dianhydride compound may comprise a compound having a fluorinated substituent. Alternatively, the dianhydride compound may consist of a compound having a fluorinated substituent. In this case, the fluorinated substituent may be a fluorinated hydrocarbon group, specifically a trifluoromethyl group. However, it is not limited thereto.

[0127] In another embodiment, the dianhydride compound may consist of a single component or a mixture of two components.

[0128] For example, dianhydride compounds may contain, but are not limited to, 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6-FDA) as shown in the formula below.

[0129]

[0130] Diamine compounds and dianhydride compounds can polymerize to form polyamic acid.

[0131] Subsequently, polyamic acid can be converted into polyimide through a dehydration reaction.

[0132] Polyimide may contain repeating units as shown in Formula A below.

[0133] Formula A

[0134]

[0135] In equation A, E, G, and e are as described above.

[0136] For example, polyimide may contain repeating units as shown in formula A-1, but is not limited thereto.

[0137] Formula A-1

[0138]

[0139] In equation A-1, n can be an integer from 1 to 400.

[0140] There are no particular restrictions on dicarbonyl compounds, but they can be, for example, compounds shown in Formula 3 below.

[0141]

Formula 3

[0142]

[0143] In Equation 3, J is selected from substituted or unsubstituted divalent C6-C. 30 Aliphatic cyclic group, substituted or unsubstituted divalent C4-C 30 Heterocyclic cycloids, substituted or unsubstituted divalent C6-C 30 Aromatic cycloyl groups, substituted or unsubstituted divalent C4-C 30 heterocyclic cycloids, substituted or unsubstituted C1-C30 Alkylene, substituted or unsubstituted C2-C 30 alkenyl, substituted or unsubstituted C2-C 30 The following groups are used: -ynyl group, -O-, -S-, -C(=O)-, -CH(OH)-, -S(=O)2-, -Si(CH3)2-, -C(CH3)2-, and -C(CF3)2-. j is an integer selected from 1 to 5. When j is 2 or more, j can be the same or different from each other. X is a halogen atom. Specifically, X can be F, Cl, Br, I, etc. More specifically, X can be Cl, but is not limited thereto.

[0144] In equation 3 above, (J) j It may be selected from the groups shown in formulas 3-1a to 3-14a below, but is not limited thereto.

[0145]

[0146] Specifically, in equation 3 above, (J) j It may be selected from the groups shown in formulas 3-1b to 3-8b below, but is not limited thereto.

[0147]

[0148] More specifically, (J) in Equation 3 j It can be the group shown in Formula 3-1b, the group shown in Formula 3-2b, or the group shown in Formula 3-3b.

[0149] In one embodiment, a mixture of at least two distinct dicarbonyl compounds can be used as the dicarbonyl compound. If two or more dicarbonyl compounds are used, at least two dicarbonyl compounds can be used as the dicarbonyl compound, wherein (J) in Formula 3 above... j Selected from the groups shown in formulas 3-1b to 3-8b above.

[0150] In another embodiment, the dicarbonyl compound may be an aromatic dicarbonyl compound containing an aromatic structure.

[0151] For example, a dicarbonyl compound may comprise a first dicarbonyl compound and / or a second dicarbonyl compound that is different from the first dicarbonyl compound.

[0152] The first dicarbonyl compound and the second dicarbonyl compound can be aromatic dicarbonyl compounds, respectively.

[0153] The first dicarbonyl compound and the second dicarbonyl compound can be different aromatic dicarbonyl compounds from each other, but are not limited to this.

[0154] If the first and second dicarbonyl compounds are aromatic dicarbonyl compounds, then they contain benzene rings. Therefore, they can contribute to improving the mechanical properties of films containing polyamide-imide resins, such as surface hardness and tensile strength.

[0155] Dicarbonyl compounds may include terephthaloyl chloride (TPC), isophthaloyl chloride (IPC), and 1,1'-biphenyl-4,4'-dicarbonyl dichloride (BPDC), or combinations thereof, as shown in the formula below. However, they are not limited to these.

[0156]

[0157] For example, the first dicarbonyl compound may contain BPDC, and the second dicarbonyl compound may contain TPC, but are not limited thereto.

[0158] Specifically, if BPDC is used as the first dicarbonyl compound and TPC as the second dicarbonyl compound in an appropriate combination, the resulting film containing polyamide-imide resin can have high antioxidant properties.

[0159] Alternatively, the first dicarbonyl compound may contain IPC (isophthaloyl chloride), and the second dicarbonyl compound may contain TPC, but is not limited thereto.

[0160] Specifically, if IPC is used as the first dicarbonyl compound and TPC as the second dicarbonyl compound in an appropriate combination, the resulting film containing polyamide-imide resin can have high antioxidant properties while reducing manufacturing costs.

[0161] Diamine compounds and dicarbonyl compounds can polymerize to form repeating units as shown in Formula B below.

[0162] Formula B

[0163]

[0164] In equation B, E, J, e, and j are as described above.

[0165] For example, diamine compounds and dicarbonyl compounds can be polymerized to form amide repeating units as shown in formulas B-1 and B-2 below.

[0166]

Form B-1

[0167]

[0168] In equation B-1, x is an integer from 1 to 400.

[0169]

Form B-2

[0170]

[0171] In equation B-2, y is an integer from 1 to 400.

[0172] Polyester base film

[0173] As another example, the base film may contain a polyester-based resin. Specifically, the base film may be a transparent polyester-based film.

[0174] Polyester-based resins can be homopolymer resins or copolymer resins formed by the polycondensation reaction of dicarboxylic acids and diols. Furthermore, polyester-based resins can be mixed resins formed by blending homopolymer resins or copolymer resins.

[0175] Examples of dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, biphenyl dicarboxylic acid, diphenoxyethylenedicarboxylic acid, diphenylsulfonedicarboxylic acid, anthracene dicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, pimelic acid, azelaic acid, sebacic acid, octanoic acid, dodecanedicarboxylic acid, etc.

[0176] In addition, examples of diols include ethylene glycol, propylene glycol, hexanediol, neopentyl glycol, 1,2-cyclohexanediethanol, 1,4-cyclohexanediethanol, decanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)sulfone, etc.

[0177] Preferably, the polyester-based resin can be an aromatic polyester-based resin with excellent crystallinity. For example, it can have polyethylene terephthalate (PET) resin as a main component.

[0178] When the base film is a polyester base film, the polyester base film may contain a polyester resin, specifically PET resin, in an amount of about 85% by weight or more, more specifically, 90% by weight or more, 95% by weight or more, or 99% by weight or more. As another example, the polyester base film may also contain polyester resins other than PET resin. Specifically, the polyester base film may also contain up to about 15% by weight of polyethylene naphthalate (PEN) resin. More specifically, the polyester base film may also contain about 0.1% by weight to 10% by weight or about 0.1% by weight to 5% by weight of PEN resin.

[0179] During the preparation of polyester-based films containing the above components, the crystallinity can be improved and the mechanical properties, such as tensile strength, can be enhanced through processes such as heating and stretching.

[0180] The base film can have an in-plane retardation (Ro) of 600 nm or lower, 500 nm or lower, 400 nm or lower, 300 nm or lower, or 200 nm or lower. Within these ranges, the occurrence of rainbow patterns can be minimized.

[0181] Furthermore, the base film can have a minimum in-plane retardation (Ro) of 200 nm or less or 150 nm or less. min Specifically, the minimum in-plane retardation of the base film can be 120 nm or lower, 100 nm or lower, 85 nm or lower, 75 nm or lower, or 65 nm or lower.

[0182] Meanwhile, the lower limit of the in-plane retardation of the base film can be 0 nm. Alternatively, the lower limit of the in-plane retardation (Ro) can be 10 nm or higher, 30 nm or higher, or 50 nm or higher, to balance optical properties and mechanical properties.

[0183] In addition, the base film can have a thickness retardation (Rth) of 4000 nm or higher, 5000 nm or higher, or 5500 nm or higher.

[0184] Furthermore, the base film can have a maximum thickness retardation (Rth) of 6000 nm or higher, such as 6500 nm or higher, such as 7500 nm or higher, such as 8000 nm or higher, such as 8500 nm or higher. max ).

[0185] Thickness retardation can be a value based on thickness measurements of 40 μm to 50 μm. Within this range, the degree of molecular orientation is high, promoting crystallization, which is preferred from a mechanical property perspective. Furthermore, as the thickness retardation (Rth) increases, the ratio of thickness retardation (Rth) to in-plane retardation (Ro) (Rth / Ro) increases, thereby effectively suppressing rainbow patterns.

[0186] Meanwhile, considering the thickness limitations and the cost of eliminating rainbow textures in the base film, the upper limit of the thickness direction delay (Rth) can be 16000 nm or lower, 15000 nm or lower, or 14000 nm or lower.

[0187] Here, the in-plane retardation (Ro) is a parameter defined by the product of the anisotropy of the refractive indices of two mutually perpendicular axes on the film (Δnxy = |nx – ny|) and the film thickness (d) (Δnxy × d), and is a measure of the degree of optical isotropy and anisotropy. Furthermore, the minimum in-plane retardation (Ro) min ) refers to the lowest value when the in-plane delay (Ro) is measured at multiple points on the membrane plane.

[0188] Furthermore, the thickness retardation is a parameter defined by the product of the average of the two birefringences Δnxz (=|nx–nz|) and Δnyz (=|ny–nz|) observed on the cross-section along the film thickness direction and the film thickness (d). Additionally, the maximum thickness retardation (Rth) max The value refers to the highest value when the thickness retardation (Rth) is measured at multiple points on the membrane plane.

[0189] Furthermore, the ratio (Rth / Ro) of the thickness retardation (Rth) to the in-plane retardation (Ro) of the base film can be 10 or higher, 15 or higher, or 20 or higher. A smaller in-plane retardation (Ro) and a larger thickness retardation (Rth) are more beneficial for preventing rainbow patterns. Therefore, the ratio (Rth / Ro) of the two values ​​is preferably kept relatively large. In particular, the maximum thickness retardation (Rth) of the base film... max ) and minimum in-plane delay (Ro) min The ratio of (Rth) max / Ro min (Can be 30 or higher, 40 or higher, 50 or higher, or 60 or higher.)

[0190] The process for preparing the base film may include: (1) extruding a composition comprising a polyester-based resin to obtain an unstretched film; (2) stretching the unstretched film in the longitudinal and transverse directions; and (3) heat-setting the stretched film.

[0191] In the above preparation process, the base film is prepared by extruding the raw material resin and preheating, stretching, and heat-setting it. In this case, the polyester-based resin composition used as the raw material for the base film is as described above. Furthermore, the extrusion can be carried out at a temperature of 230°C to 300°C or 250°C to 280°C.

[0192] The base film is preheated at a certain temperature before stretching. Based on the glass transition temperature (Tg) of the polyester resin, the preheating temperature is set to be in the range of Tg+5℃ to Tg+50℃, and specifically within the range of 70℃ to 90℃. Within this range, the base film is sufficiently flexible to facilitate stretching and effectively prevents breakage during the stretching process.

[0193] Stretching is performed via biaxial stretching. For example, it can be performed simultaneously or sequentially in both the transverse (or tenter direction, TD) and longitudinal (or machine direction, MD) directions. Preferably, it can be performed sequentially in the biaxial stretching direction, wherein stretching is first performed in one direction and then in a direction perpendicular to that direction.

[0194] The longitudinal stretch ratio can range from 2.0 to 5.0, more specifically, from 2.8 to 3.5. Furthermore, the transverse stretch ratio can range from 2.0 to 5.0, more specifically, from 2.9 to 3.7. Preferably, the longitudinal stretch ratio (d1) and the transverse stretch ratio (d2) are similar to each other. Specifically, the ratio of the longitudinal stretch ratio (d2) to the transverse stretch ratio (d1) (d2 / d1) can be 0.5 to 1.0, 0.7 to 1.0, or 0.9 to 1.0. The stretch ratios (d1 and d2) each refer to a ratio of the length after stretching to the length before stretching of 1.0. Furthermore, the stretching speed can be from 6.5 m / min to 8.5 m / min, but is not particularly limited thereto.

[0195] Stretched sheets can be heat-set at 150°C to 250°C, more specifically 160°C to 230°C. The heat-setting process can last from 5 seconds to 1 minute, more specifically 10 seconds to 45 seconds.

[0196] After heat setting begins, the sheet can be relaxed in the longitudinal and / or transverse direction at a temperature range of 150°C to 250°C.

[0197] According to one embodiment, a laminate containing a polyester base film as the base film can simultaneously enhance surface hardness and elasticity.

[0198] The martensitic hardness of the laminate according to one embodiment can be, for example, 170 N / mm. 2 Or higher, 175 N / mm 2 Or higher, 180 N / mm 2 Or higher, 181.25 N / mm 2 Or higher, or 185 N / mm 2 Or higher, and 250 N / mm 2 Or lower, 200 N / mm 2 Or lower, 195 N / mm 2 Or lower, or 190 N / mm 2 Or even lower. As a specific example, when the hard coating surface is measured by nanoindentation testing according to ISO 14577-1:2002(E) standard, the martensitic hardness (HM) of the laminate can be 175 N / mm². 2 Or higher, more specifically, 175 N / mm 2 Up to 200 N / mm 2 .

[0199] Furthermore, the HV increase of the laminate (N / mm) is calculated using the following equation. 2 It can be 5N / mm 2 Or higher, specifically 7 N / mm 2 Or higher or 10 N / mm 2 Or higher, for a more specific example, 5 N / mm2 Up to 25 N / mm 2 .

[0200] HM increase (N / mm) 2 ) = HM1 (N / mm 2 )-HM2(N / mm 2 )

[0201] Wherein, HV1 is the Martens hardness (HM) of the laminate (N / mm). 2 HV2 is the Martens hardness (HM) (N / mm) of a laminated film with a hard coating removed. 2 ).

[0202] According to one embodiment, the Vickers hardness (HV) of the laminate can be, for example, 20 N / mm. 2 Or higher, 25 N / mm 2 Or higher, 29 N / mm 2 Or higher, or 30 N / mm 2 Or higher, and 50 N / mm 2 Or lower, 45 N / mm 2 Or lower, 40 N / mm 2 Or lower, or 35 N / mm 2 Or even lower. As a specific example, when the Vickers hardness (HV) of a hard coating surface is measured by nanoindentation testing according to ISO 14577-1:2002(E), the laminate can be 29 N / mm². 2 Or higher, more specifically, 29 N / mm 2 Up to 50 N / mm 2 .

[0203] Furthermore, the HV increase of the laminate (N / mm) is calculated using the following equation. 2 It can be 1.5 N / mm 2 Or higher, specifically 2.0 N / mm 2 Or higher or 2.5 N / mm 2 Or higher, for a more specific example, 1.5 N / mm 2 Up to 7.0 N / mm 2 .

[0204] HV increase (N / mm) 2 =HV1 (N / mm) 2 )-HV2(N / mm 2 )

[0205] Here, HV1 is the Vickers hardness (HV) of the laminate (N / mm²). 2 HV2 is the Vickers hardness (HV) (N / mm²) of a laminated film with a hard coating removed.2 ).

[0206] The indentation hardness (H) of the laminate according to one embodiment IT It can be, for example, 250 N / mm 2 Or higher, 270 N / mm 2 Or higher, 290 N / mm 2 Or higher, 310 N / mm 2 Or higher, 320N / mm 2 Or higher, or 330 N / mm 2 Or higher, and 500 N / mm 2 Or lower, 450 N / mm 2 Or lower, 400 N / mm 2 Or lower, or 370 N / mm 2 Or lower. As a specific example, when measuring the surface of a hard coating using a nanoindentation test according to ISO 14577-1:2002(E), the indentation hardness (H) of the laminate is... IT It can be 310 N / mm 2 Or higher, more specifically, 310 N / mm 2 Up to 450 N / mm 2 In the above indentation hardness (H) IT Within a certain range, its plastic properties, such as impact resistance, are manifested, making it suitable for use as a cover window for display devices.

[0207] Furthermore, the H of the laminated film can be calculated using the following equation. IT Increase (N / mm) 2 It can be 10 N / mm 2 Or higher, specifically 15 N / mm 2 Or higher, 20N / mm 2 Or higher, or 25 N / mm 2 Or higher, for a more specific example, 10 N / mm 2 Up to 70 N / mm 2 .

[0208] H IT Increase (N / mm) 2 )=H IT 1 (N / mm) 2 )-H IT 2 (N / mm) 2 )

[0209] Here, H IT 1 is the indentation hardness (H) of the laminate. IT (N / mm) 2 ), H IT2 is the indentation hardness (H) of a laminated film with a hard coating removed. IT (N / mm) 2 ).

[0210] According to one embodiment, the indentation modulus (E) of the laminated film IT The pressure can be, for example, 2500 MPa or higher, 2800 MPa or higher, 2900 MPa or higher, 2935 MPa or higher, or 2950 MPa or higher, and 4000 MPa or lower, 3500 MPa or lower, 3300 MPa or lower, or 3100 MPa or lower. As a specific example, when measuring the surface of a hard coating using a nanoindentation test according to ISO 14577-1:2002(E) standard, the indentation modulus (E) of the laminate is... IT It can be 2900 MPa or higher, more specifically, 2900 MPa to 4000 MPa.

[0211] Indentation creep (C) of a laminate according to one embodiment IT The percentage can be, for example, 3.0% or higher, 3.5% or higher, 3.7% or higher, 4.0% or higher, or 4.1% or higher, and 6.0% or lower, 5.5% or lower, 5.0% or lower, 4.5% or lower, or 4.3% or lower. As a specific example, when measuring the surface of a hard coating using a nanoindentation test according to ISO 14577-1:2002(E) standard, the indentation creep (C) of the laminate is... IT It can be 3.5% or higher, more specifically, 3.5% to 5.0%.

[0212] The recovery relationship of the laminate according to one embodiment (η) IT The percentage can be, for example, 50% or higher, 55% or higher, 60% or higher, 61% or higher, 63% or higher, or 63.5% or higher, and 85% or lower, 80% or lower, 75% or lower, or 70% or lower. As a specific example, when measuring a hard coating surface using a nanoindentation test according to ISO 14577-1:2002(E), the recovery relationship (η) of the laminate is... IT It can be 63.6% or higher, more specifically, 63.6% to 75%.

[0213] The recovery rate of the laminate according to one embodiment can be, for example, 60% or higher, 65% or higher, 70% or higher, or 73.35% or higher, and 90% or lower, 85% or lower, 80% or lower, or 75% or lower. As a specific example, when the hard coating surface is measured by nanoindentation testing according to ISO 14577-1:2002(E), the recovery rate of the laminate can be 65% or higher, more specifically, 65% to 90%. The recovery rate can be calculated using the following equation.

[0214] Recovery rate (%) = [(h max(30mN时) -h p ) / h max(30mN时) ]×100

[0215] Here, h max (At 30mN) is the maximum indentation depth (μm) achieved when a 30mN force is applied downwards to the hard coating surface for 15 seconds and held (creep) for 5 seconds. p It is the indentation depth (μm) that has not recovered even after the force is released.

[0216] Furthermore, the recovery rate increase (%) of the laminate can be 5% or higher, specifically 8% or higher or 9% or higher, or, as a more specific example, 5% to 15%, calculated using the following equation.

[0217] Recovery rate increase (%) = Recovery rate 1 (%) - Recovery rate 2 (%)

[0218] Here, recovery rate 1 is the recovery rate (%) of the laminated film, and recovery rate 2 is the recovery rate (%) of the film with the hard coating removed from the laminated film.

[0219] Hard coating (200)

[0220] A hard coating (200) is disposed on one side of the base film (100).

[0221] The rigid coating can have an upper side and a lower side, where the lower side can face the base film and the upper side can be the outermost exposed side. Furthermore, the lower side of the rigid coating can directly contact one side of the base film, or be bonded to one side of the base film via an additional coating. For example, the rigid coating can be formed directly on one side of the base film.

[0222] Hard coatings can enhance the mechanical and / or optical properties of laminates. Furthermore, hard coatings can also incorporate anti-glare, anti-fouling, and antistatic properties.

[0223] Hard coatings may contain at least one of organic components, inorganic components, and organic-inorganic composite components as hard coating agents.

[0224] For example, a hard coating may comprise an organic resin. Specifically, the organic resin may be a curable resin. Therefore, a hard coating may be a curable coating. Furthermore, the organic resin may be an adhesive resin.

[0225] Specifically, the hard coating may comprise at least one selected from the group consisting of urethane acrylate compounds, acrylate compounds, acrylic compounds, and epoxy acrylate compounds. More specifically, the hard coating may comprise urethane acrylate compounds and acrylate compounds. Even more specifically, the hard coating may comprise urethane acrylate compounds, acrylate compounds, and acrylic compounds, but is not limited thereto.

[0226] urethane acrylate compounds may contain urethane bonds as repeating units and may have multiple functional groups.

[0227] The urethane acrylate compound can be a compound in which the urethane compound formed by reacting a diisocyanate compound with a polyol has its terminal acrylate group substituted. For example, the diisocyanate compound can comprise at least one of a straight-chain, branched, or cyclic aliphatic diisocyanate compound having 4 to 12 carbon atoms and an aromatic diisocyanate compound having 6 to 20 carbon atoms. The polyol comprises 2 to 4 hydroxyl groups (-OH) and can be a straight-chain, branched, or cyclic aliphatic polyol compound having 4 to 12 carbon atoms or an aromatic polyol compound having 6 to 20 carbon atoms. The terminal substitution of the acrylate group is achieved by an acrylate compound having a functional group capable of reacting with the isocyanate group (-NCO). For example, an acrylate compound having hydroxyl or amino groups can be used, or a hydroxyalkyl acrylate or an aminoalkyl acrylate having 2 to 10 carbon atoms can be used.

[0228] ethyl carbamate acrylate compounds can contain 2 to 15 functional groups.

[0229] Examples of urethane acrylate-based compounds include, but are not limited to, difunctional urethane acrylate oligomers with a weight-average molecular weight of 1,400 to 25,000, trifunctional urethane acrylate oligomers with a weight-average molecular weight of 1,700 to 16,000, tetrafunctional urethane acrylate oligomers with a weight-average molecular weight of 500 to 2,000, hexafunctional urethane acrylate oligomers with a weight-average molecular weight of 818 to 2,600, nonfunctional urethane acrylate oligomers with a weight-average molecular weight of 2,500 to 5,500, decafunctional urethane acrylate oligomers with a weight-average molecular weight of 3,200 to 3,900, and pentafunctional urethane acrylate oligomers with a weight-average molecular weight of 2,300 to 20,000.

[0230] The glass transition temperature (Tg) of urethane acrylate compounds can be -80°C to 100°C, -80°C to 90°C, -80°C to 80°C, -80°C to 70°C, -80°C to 60°C, -70°C to 100°C, -70°C to 90°C, -70°C to 80°C, -70°C to 70°C, -70°C to 60°C, -60°C to 100°C, -60°C to 90°C, -60°C to 80°C, -60°C to 70°C, -60°C to 60°C, -50°C to 100°C, -50°C to 90°C, -50°C to 80°C, -50°C to 70°C, or -50°C to 60°C.

[0231] The acrylate compound may be at least one selected from the group consisting of substituted or unsubstituted acrylates and substituted or unsubstituted methacrylates. The acrylate compound may contain 1 to 10 functional groups.

[0232] Examples of acrylate-based compounds include, but are not limited to, trimethylolpropane triacrylate (TMPTA), trimethylolpropane ethoxytriacrylate (TMPEOTA), glycerol propoxylated triacrylate (GPTA), pentaerythritol tetraacrylate (PETA), and dipentaerythritol hexaacrylate (DPHA).

[0233] The weight-average molecular weight of acrylate-based compounds can be 500 to 6000, 500 to 5000, 500 to 4000, 1000 to 6000, 1000 to 5000, 1000 to 4000, 1500 to 6000, 1500 to 5000, or 1500 to 4000. The acrylate equivalent of acrylate-based compounds can be 50 g / eq. to 300 g / eq., 50 g / eq. to 200 g / eq., or 50 g / eq. to 150 g / eq.

[0234] Acrylic compounds may contain 1 to 10 functional groups. Examples of acrylic compounds include, but are not limited to, monofunctional acrylate oligomers with a weight average molecular weight of 100 to 300, difunctional acrylate oligomers with a weight average molecular weight of 250 to 2000, and acrylate oligomers with a weight average molecular weight of 1000 to 3000.

[0235] Epoxy acrylate compounds may contain 1 to 10 functional groups. Examples of epoxy acrylate compounds include, but are not limited to, monofunctional epoxy acrylate oligomers with a weight-average molecular weight of 100 to 300, difunctional epoxy acrylate oligomers with a weight-average molecular weight of 250 to 2000, and tetrafunctional epoxy acrylate oligomers with a weight-average molecular weight of 1000 to 3000. The epoxy equivalent of the epoxy acrylate compound may be 50 g / eq. to 300 g / eq., 50 g / eq. to 200 g / eq., or 50 g / eq. to 150 g / eq.

[0236] The content of organic resin can be from 30% to 100% by weight, depending on the total weight of the hard coating. Specifically, the content of organic resin can be from 40% to 90% by weight, or from 50% to 80% by weight, depending on the total weight of the hard coating.

[0237] The hard coating may optionally contain fillers. The fillers can be, for example, inorganic particles. Examples of fillers include silica, barium sulfate, zinc oxide, and aluminum oxide. The particle size of the filler can be from 1 nm to 100 nm. Specifically, the particle size of the filler can be from 5 nm to 50 nm or from 10 nm to 30 nm. The filler can contain inorganic fillers with different particle size distributions. For example, the filler can contain a first inorganic filler with a D50 of 20 nm to 35 nm and a second inorganic filler with a D50 of 40 nm to 130 nm. Based on the total weight of the hard coating, the filler content can be 25% by weight or more, 30% by weight or more, or 35% by weight or more. Furthermore, based on the total weight of the hard coating, the filler content can be 50% by weight or less, 45% by weight or less, or 40% by weight or less. Preferably, the hard coating does not contain inorganic fillers such as silica. In this case, for example, the adhesion between the base film and the hard coating in the above composition can be enhanced.

[0238] Hard coatings may also contain photoinitiators. Examples of photoinitiators include, but are not limited to, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, methyl benzoylcarbamate, α,α-dimethoxy-α-phenylacetophenone, 2-benzoyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. In addition, commercially available products include Irgacure 184, Irgacure 500, Irgacure 651, Irgacure 369, Irgacure 907, Darocur 1173, Darocur MBF, Irgacure 819, Darocur TPO, Irgacure 907, and Esacure KIP100F. Photoinitiators can be used alone or in combination of two or more.

[0239] Hard coatings may also contain antifouling agents. For example, hard coatings may contain fluorinated compounds. Fluorinated compounds can have antifouling properties. Specifically, fluorinated compounds may be acrylic compounds having a perfluoroalkyl group. Specific examples may include, but are not limited to, perfluorohexyl ethyl acrylate.

[0240] Hard coatings may also contain antistatic agents. Antistatic agents may contain ionic surfactants. For example, ionic surfactants may contain ammonium salts or alkyl quaternary ammonium salts, and ammonium salts and alkyl quaternary ammonium salts may contain halides, such as chlorides or bromides.

[0241] In addition, hard coatings may also contain additives such as surfactants, UV absorbers, UV stabilizers, anti-yellowing agents, leveling agents, and dyes to improve color values. For example, surfactants may be monofunctional to bifunctional fluoroacrylates, fluorosurfactants, or silicone-based surfactants. Surfactants may be present in the hard coating in dispersed or crosslinked forms. Furthermore, examples of UV absorbers include benzophenone compounds, benzotriazole compounds, and triazine compounds. Examples of UV stabilizers include tetramethylpiperidine, etc. The content of additives can be adjusted in various ways without impairing the physical properties of the hard coating. For example, the content of additives may be from 0.01% by weight to 10% by weight, but is not limited to this, based on the weight of the hard coating.

[0242] Hard coatings can consist of a single layer, two layers, or more. For example, a hard coating formed as a single layer can simultaneously increase the durability of the laminate and provide fingerprint or stain resistance.

[0243] The thickness of the hard coating can be 2 μm or thicker, 3 μm or thicker, 5 μm or thicker, or 10 μm or thicker, and 50 μm or thinner, 30 μm or thinner, 20 μm or thinner, or 10 μm or thinner. For example, the thickness of the hard coating can be from 2 μm to 20 μm. Specifically, the thickness of the hard coating can be from 5 μm to 20 μm. If the hard coating is too thin, it may not have sufficient surface hardness to protect the base film, resulting in deterioration of the durability of the laminate. If it is too thick, the flexibility of the laminate may deteriorate, and the overall thickness of the laminate may increase, which may be detrimental to film formation.

[0244] Therefore, the hard coating can be formed from a hard coating composition comprising at least one of an organic-based composition, an inorganic-based composition, and an organic-inorganic composite composition. For example, the hard coating composition may comprise at least one of an acrylic compound, a siloxane compound, and a silsesquioxane compound. Furthermore, the hard coating may also comprise inorganic particles. As a specific example, the hard coating can be formed from a hard coating composition comprising an urethane acrylate-based compound, an acrylate-based compound, and a fluorine-based compound.

[0245] Hard coatings can be formed by coating a hard coating composition onto a base film, followed by drying and curing.

[0246] The hard coating composition may contain the above-mentioned organic resin, photoinitiator, antifouling agent, antistatic agent, other additives and / or solvent.

[0247] Examples of organic solvents include alcohol-based solvents such as methanol, ethanol, isopropanol, and butanol; alkoxy-based solvents such as 2-methoxyethanol, 2-ethoxyethanol, and 1-methoxy-2-propanol; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, and cyclohexanone; ether-based solvents such as propylene glycol monopropyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, and diethylene glycol-2-ethylhexyl ether; and aromatic solvents such as benzene, toluene, and xylene, which can be used alone or in combination.

[0248] There are no particular limitations on the content of the organic solvent, as it can be adjusted in various ways without impairing the physical properties of the hard coating composition. Organic solvents can be used such that the weight ratio of the solid content of the components in the coating composition to the organic solvent is from about 30:70 to about 99:1. If the content of the organic solvent is within the above range, the composition can have suitable flowability and coatability.

[0249] The hard coating composition may contain 10% to 30% by weight of an organic resin, 0.1% to 5% by weight of a photoinitiator, 0.01% to 2% by weight of an antifouling agent, and 0.1% to 10% by weight of an antistatic agent. According to this composition, the mechanical properties of the hard coating, as well as its antifouling and antistatic properties, can be simultaneously enhanced.

[0250] Hard coating compositions can be applied to a base film by rod coating, knife coating, roller coating, doctor blade coating, die coating, microgravure coating, comma coating, groove die coating, lip coating, or solution casting.

[0251] Subsequently, the organic solvent contained in the hard coating composition can be removed by a drying step. The drying step can be carried out at a temperature of 40°C to 100°C, preferably 40°C to 80°C, 50°C to 100°C, or 50°C to 80°C for about 1 minute to 20 minutes, preferably 1 minute to 10 minutes or 1 minute to 5 minutes.

[0252] Subsequently, the hard coating composition layer can be cured by light and / or heat.

[0253] Elastic layer (300)

[0254] The elastic layer (300) contains polyether block amide (PEBA).

[0255] Polyether block amides consist of two phases: polyamide segments (rigid segments) and polyether segments (flexible segments).

[0256] Rigid segments can be crystalline or semi-crystalline. Flexible segments can be amorphous. For example, amorphous segments can be the matrix, and crystalline segments can be distributed within the matrix.

[0257] Because polyether block amides contain both rigid and flexible segments, the elastic layer can have relatively high mechanical strength while also possessing flexible and / or elastic properties.

[0258] The elastic layer can have relatively high mechanical strength, while also having flexible and / or elastic properties.

[0259] The melting point of polyamide segments can be about 80°C or higher, specifically about 130°C to 180°C. They are essentially crystalline and constitute rigid segments. Conversely, the glass transition temperature of polyether segments can be about -40°C or lower, specifically -80°C to -40°C. They exist in the low-temperature region and can constitute essentially amorphous, flexible segments.

[0260] Polyether block amides can be polyethers composed of polyamides containing two or more carboxyl groups in the molecule and ethers containing two or more hydroxyl groups in the molecule.

[0261] The elastic layer may contain polyether block amides. The polyether block amide may contain at least one copolymer comprising polyether blocks and polyamide blocks. Therefore, the polyether block amide contains at least one polyether block and at least one polyamide block.

[0262] A copolymer containing polyether blocks and polyamide blocks (polyether block amide) can be a copolymer obtained by polycondensation reaction of polyether blocks containing reactive ends and polyamide blocks containing reactive ends.

[0263] For example, a polyether block amide can be a condensation polymer containing a polyamide block with a diamine end and a polyoxyalkylene block with a dicarboxylic acid end.

[0264] As another example, polyether block amides can be condensation polymers comprising polyamide blocks with dicarboxylic acid ends and polyoxyalkylene blocks with diamine ends.

[0265] Polyoxyalkylene blocks can be obtained by cyanoethylation and hydrogenation of aliphatic α,ω-dihydroxy polyoxyalkylene blocks known as polyether diols.

[0266] Polyether block amides can be condensation polymers comprising polyamide blocks with dicarboxylic acid terminals and polyether glycol blocks. In this case, the polyether block amide is a polyether ester amide.

[0267] For example, polyamide blocks containing dicarboxylic acid chain ends can be included in condensation polymers of polyamide precursors in the presence of chain-limited dicarboxylic acids.

[0268] For example, polyamide blocks containing diamine chain ends can be included in condensation polymers of polyamide precursors in the presence of chain-limited diamines.

[0269] For example, polyamide blocks containing dicarboxylic acid chain ends may be included in condensation polymers of α,ω-aminocarboxylic acids, lactams, or dicarboxylic acids and diamines in the presence of chain-limited dicarboxylic acids.

[0270] Polyamide 12 or polyamide 6 is preferred as the polyamide block.

[0271] Polyether block polyamides may contain blocks with a randomly distributed unit structure.

[0272] Advantageously, the following three types of polyamide blocks can be used.

[0273] As a first type, the polyamide block may comprise a condensation polymer of a carboxylic acid and an aliphatic or aryliphatic diamine. The carboxylic acid may have 4 to 20 carbon atoms, preferably 6 to 18 carbon atoms. The aliphatic or aryliphatic diamine may have 2 to 20 carbon atoms, preferably 6 to 14 carbon atoms.

[0274] Carboxylic acids, especially dicarboxylic acids, can be, for example, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexyldicarboxylic acid, 1,4-succinic acid, adipic acid, azelaic acid, octanoic acid, sebacic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and dimer fatty acids.

[0275] The diamine can be, for example, 1,5-tetramethylenediamine, 1,6-hexamethylenediamine, 1,10-decamethylenediamine, 1,12-dodecylmethylenediamine, trimethyl-1,6-hexamethylenediamine, 2-methyl-1,5-pentamethylenediamine, isomers of bis(3-methyl-4-aminocyclohexyl)methane (BMACM), 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), bis(p-aminocyclohexyl)methane (PACM), isophorone diamine (IPD), 2,6-bis(aminomethyl)norbornene (BAMN), piperazine (Pip), m-xylenediamine (MXD), and p-xylenediamine (PXD).

[0276] Specifically, the polyamide blocks of the first type may include PA412, PA414, PA418, PA610, PA612, PA614, PA618, PA912, PA1010, PA1012, PA1014, PA1018, MXD6, PXD6, MXD10, or PXD10.

[0277] As a second type, the polyamide block may comprise a condensation polymer of at least one α,ω-aminocarboxylic acid and / or at least one lactam, each having 6 to 12 carbon atoms, in the presence of a dicarboxylic acid or diamine having 4 to 12 carbon atoms. Examples of lactams include caprolactam, heptanolactam, and dodecanolactam. Examples of α,ω-aminocarboxylic acids include aminohexanoic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. Specifically, the polyamide block of the second type may comprise polyamide 11, polyamide 12, or polyamide 6.

[0278] As a third type, the polyamide block may comprise a condensation polymer of at least one α,ω-aminocarboxylic acid (or at least one lactam), at least one diamine, and at least one dicarboxylic acid. In this case, the polyamide (PA) block can be prepared by a condensation reaction of a diamine, a diacid, and one (or more) comonomers.

[0279] As a diamine, for example, a linear aliphatic diamine, an aromatic diamine, etc., can be used. As a diacid, for example, an alicyclic diacid, an aliphatic diacid, an aromatic diacid, etc., can be used. As a diacid, for example, a dicarboxylic acid can be used. The comonomer can be selected from lactams, α,ω-aminocarboxylic acids, and mixtures comprising substantially equimolar amounts of one or more diamines and one or more dicarboxylic acids. Based on the total amount of the combined polyamide precursor monomers, the amount of comonomer can be 50% by weight or less, preferably 20% by weight or less, advantageously 10% by weight or less.

[0280] According to the third type of polycondensation reaction, it can be carried out in the presence of a chain restrictor selected from dicarboxylic acids. Specifically, dicarboxylic acids can be used as chain restrictors, and dicarboxylic acids can be introduced in stoichiometric excess relative to one or more diamines.

[0281] In another form of the third type, the polyamide block may comprise at least two α,ω-aminocarboxylic acids having 6 to 12 carbon atoms, or at least two lactams, or condensation polymers of lactams and aminocarboxylic acids having different numbers of carbon atoms, optionally in the presence of a chain restrictor. The aliphatic α,ω-aminocarboxylic acid may be, for example, aminohexanoic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, or 12-aminododecanoic acid. The lactam may be, for example, caprolactam, heptanolactam, or dodecalactam.

[0282] Aliphatic diamines can be, for example, hexamethylenediamine, dodecamethyldiamine, or trimethylhexamethylenediamine.

[0283] Alicyclic dicarboxylic acids can be, for example, 1,4-cyclohexanedicarboxylic acid. Other alicyclic dicarboxylic acids can be, for example, succinic acid, adipic acid, azelaic acid, octanoic acid, sebacic acid, dodecanedicarboxylic acid, dimer fatty acids (preferably with a dimer content of 98% or higher; preferably hydrogenated; sold under the trade name Pripol by Uniqema or Empol by Henkel) or polyoxyalkylene-α,ω-dicarboxylic acids.

[0284] Aromatic dicarboxylic acids can be, for example, terephthalic acid or isophthalic acid.

[0285] Alicyclic diamines can be isomers of, for example, bis(3-methyl-4-aminocyclohexyl)methane (BMACM) and 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP) or bis(p-aminocyclohexyl)methane (PACM).

[0286] Other diamines include, for example, isophorone diamine (IPDI), 2,6-bis(aminomethyl)norbornene (BAMN), and piperazine.

[0287] Examples of arylita-diamines include, but are not limited to, m-xylenediamine (MXD) and p-xylenediamine (PXD).

[0288] Examples of the third type of polyamide blocks include PA 66 / 6, PA66 / 610 / 11 / 12, etc.

[0289] In PA66 / 6, 66 represents the hexamethylenediamine unit condensed with adipic acid, and 6 represents the unit introduced by the condensation of caprolactam.

[0290] In PA66 / 610 / 11 / 12, 66 represents a hexamethylenediamine unit condensed with adipic acid, 610 represents a hexamethylenediamine unit condensed with sebacic acid, 11 represents a unit introduced by condensation with aminoundecanoic acid, and 12 represents a unit introduced by condensation with dodecanoic acid.

[0291] The number-average molecular weight of polyamide blocks can be from 400 to 20,000, specifically from 500 to 10,000.

[0292] The polyether block can be, for example, at least one polyalkylene ether polyol, such as polyalkylene ether glycol. Specifically, the polyether block can be selected from polyethylene glycol (PEG), polypropylene glycol (PPG), polytrimethylene ether glycol (PO3G), polytetramethylene ether glycol (PTMG), mixtures thereof, and copolymers thereof.

[0293] The polyether block may comprise a polyoxyalkylene unit with an NH2 terminal. This unit can be introduced by cyanoacetylation of an aliphatic α,ω-dihydroxypolyoxyalkylene unit known as a polyether diol. Specifically, Jeffamine (e.g., Huntsman's Jeffamine) can be used. TM (D400, D2000, ED2003 or XTJ542).

[0294] At least one polyether block comprises, for example, at least one polyether selected from polyalkylene ether polyols such as PEG, PPG, PO3G and PTMG, polyethers with NH2 at the chain end and polyoxyalkylene sequences, copolymers (ether copolymers) arranged randomly and / or in block arrangement and mixtures thereof.

[0295] Based on the total weight of the copolymer, the amount of polyether block can be from 10% to 80% by weight, specifically from 20% to 60% by weight or from 20% to 40% by weight. The number average molecular weight of the polyether block can be from 200 to 1000, specifically from 400 to 800 or from 500 to 700.

[0296] The polyether block can be introduced from polyethylene glycol, polypropylene glycol or polytetramethylene ether glycol.

[0297] Polyether blocks can be copolymerized with polyamide blocks containing carboxyl ends to form polyether block amides.

[0298] Polyether blocks can be converted into polyether diamines through amination, and then condensed with polyamide blocks containing carboxyl ends to form polyether block amides.

[0299] Polyether blocks can be mixed with polyamide precursors and chain restrictors to form polyether block amides containing statistically dispersed units.

[0300] The polyether can be, for example, polyethylene glycol (PEG), polypropylene glycol (PPG), or polytetramethylene ether glycol (PTMG). Polytetramethylene ether glycol is also known as polytetrahydrofuran (PTHF). Polyether blocks can be introduced into the chain of the polyether block amide in the form of glycols or diamines, wherein the polyether blocks are referred to as PEG blocks, PPG blocks, and PTMG blocks, respectively.

[0301] Furthermore, even if the polyether block contains units other than those derived from ethylene glycol (-OC2H4-), propylene glycol (-O-CH2-CH(CH3)-) or tetramethylene ether glycol (-O-(CH2)4-), such polyether blocks should be understood as being within the scope of the embodiments.

[0302] The number-average molecular weight of the polyamide blocks can be from 300 to 15,000 or from 600 to 5,000. The number-average molecular weight of the polyether blocks can be from 100 to 6,000, preferably from 200 to 3,000.

[0303] Specifically, based on the total weight of the polyether block amide, the content of polyamide blocks contained in the polyether block amide can be 50% by weight or more. This may imply the possibility of a statistical distribution within the polymer chain. Specifically, the content of polyamide blocks can be from 50% by weight to 80% by weight. Furthermore, based on the total weight of the polyether block amide, the content of polyether blocks contained in the polyether block amide can be from 20% by weight to 50% by weight.

[0304] The number-average molecular weight ratio of the polyamide blocks to the polyether blocks in the copolymer can be, for example, from 1:0.25 to 1:1. Specifically, the number-average molecular weight ratio of the polyamide blocks to the polyether blocks in the copolymer can be 1000 / 1000, 1300 / 650, 2000 / 1000, 2600 / 650, or 4000 / 1000.

[0305] Polyether block amides can be prepared in a two-step process, involving the first step of preparing polyamide blocks and polyether blocks, and the second step of polycondensing the polyamide blocks and polyether blocks to prepare elastic polyether block amides. Alternatively, polyether block amides can be prepared by a one-step polycondensation reaction of monomers.

[0306] The Shore D hardness of polyether block amides can be, for example, 20 to 75, specifically 30 to 70.

[0307] The intrinsic viscosity of polyether block amides can be measured at 25°C using m-cresol and ranges from 0.8 to 2.5. The intrinsic viscosity can be measured according to ISO 307:2019. Specifically, the intrinsic viscosity in solution can be measured at 25°C using an Ubbelohde viscometer in a 0.5% by weight m-cresol solution.

[0308] Examples of polyether block amides include Arkema's Pebax. TM and Pebax TM Rnew TM And Evonik's VESTAMID TM E, but not limited to this.

[0309] The optical properties of the elastic layer can be adjusted within a certain range. Therefore, it is advantageous for cover windows used in display devices.

[0310] The haze of the elastic layer can be, for example, 3% or lower, specifically 2% or lower, 1.5% or lower, or 1.2% or lower. Furthermore, the haze of the elastic layer can be 0.01% or higher, or 0.1% or higher.

[0311] The average visible light transmittance of the elastic layer can be, for example, 85% or more, specifically 88% or more, or 90% or more. Furthermore, the average visible light transmittance of the elastic layer can be 99.99% or lower.

[0312] The thickness of the elastic layer can be 20 μm or more, 30 μm or more, 50 μm or more, or 100 μm or more, and 500 μm or less, 400 μm or less, 300 μm or less, or 200 μm or less. As a specific example, the thickness of the base film can be from 20 μm to 500 μm, more specifically from 50 μm to 200 μm.

[0313] Display device

[0314] According to one embodiment, the display device includes the aforementioned laminated film in a cover plate. Specifically, the laminated film may form a cover window in the display device.

[0315] refer to Figure 1 and Figure 2 According to one embodiment, the display device (1) includes a display panel (20); and a cover window (10) disposed on the front side of the display panel (20), wherein the cover window (10) includes a base film (100); a hard coating (200) disposed on one side of the base film (100); and an elastic layer (300) disposed on the other side of the base film (100), the elastic layer (300) comprising polyether block amide.

[0316] For example, the base film may contain a polyimide-based resin. As another example, the base film may contain a polyester-based resin.

[0317] The laminate included in the display device has the same structure and properties as the laminate described above.

[0318] The display device can be flexible. For example, the display device can be a flexible display device. Specifically, it can be a foldable display device. More specifically, the foldable display device can be an inward-folding or outward-folding type, depending on the folding direction.

[0319] Figure 5a and 5b Flexible display devices with inward folding and outward folding types are shown respectively. (Reference) Figure 5a The display device can be an inwardly folding flexible display device (1a) with the screen located inside the folding direction. Alternatively, refer to... Figure 5b The display device can be an outward-folding flexible display device with the screen located on the outside of the folding direction (1b).

[0320] refer to Figure 1 The display device (1) includes a cover window (10), a display panel (20), a circuit board (30), and a frame (40) that protects them. The cover window (10) includes a laminated film as described above.

[0321] As an example, the display panel (20) may be a liquid crystal display (LCD) panel. As another example, the display panel (20) may be an organic light-emitting display (OLED) panel. The organic light-emitting display device may include a front polarizer and an organic light-emitting display panel. The front polarizer may be disposed on the front side of the organic light-emitting display panel. More specifically, the front polarizer may be bonded to the side of the organic light-emitting display panel that displays the image. The organic light-emitting display panel displays the image by means of self-emission of the pixel units. The organic light-emitting display panel includes an organic light-emitting substrate and a driving substrate. The organic light-emitting substrate includes a plurality of organic light-emitting units corresponding to each pixel. Each organic light-emitting unit includes a cathode, an electron transport layer, an emissive layer, a hole transport layer, and an anode. The driving substrate is operatively coupled to the organic light-emitting substrate. That is, the driving substrate may be coupled to the organic light-emitting substrate to apply a driving signal, such as a driving current. More specifically, the driving substrate may drive the organic light-emitting substrate by applying a current to each organic light-emitting unit.

[0322] In addition, an adhesive layer may be provided between the cover window (10) and the display panel (20). For example, the adhesive layer may contain an optically transparent adhesive.

[0323] Invention Model

[0324] The embodiments described below are intended to aid understanding and are not intended to limit the scope of implementation.

[0325] A. Laminated film containing a polyimide-based film

[0326] Various laminates containing polyimide-based films were prepared and evaluated.

[0327] Example A1

[0328] Step (1) Formation of hard coating

[0329] A hard coating composition having the composition shown in Table 1 was applied to one side of a 50 μm thick transparent polyimide-based film (TPI, SKC) using a die-coating method. Subsequently, the coating was heat-treated at 60°C for 3 minutes to dry the solvent, and then cured by UV light with a dose of 1 J to prepare a hard coating with a thickness of approximately 5 μm.

[0330] Table 1

[0331]

[0332] Step (2) Lamination of the elastic layer

[0333] polyether block amide resin (Arkema Pebax) TM Rnew TM72R53 (Arkema) is fed into an extruder, melt-mixed at about 220°C, extruded into a single layer, and laminated with a base film that has formed a hard coating to prepare a laminated film. The laminated film has a 50 μm thick PEBA layer formed on the base film with the hard coating.

[0334] Example A2

[0335] In addition to the use of polyether block amide resin (Arkema Pebax) in step (2) of Example A1 TM Rnew TM In addition to preparing a PEBA membrane using 55R53 (Arkema), a laminate was prepared in the same manner as in Example A1.

[0336] Comparative Example A1

[0337] polyether block amide resin (Arkema Pebax) TM Rnew TM 72R53 (Arkema) is fed into an extruder, melt-mixed at about 220°C, extruded into a single layer, and laminated with a 50 μm thick transparent polyimide base film (TPI, SKC) to prepare a laminated film, which has a 50 μm thick PEBA layer formed on the base film.

[0338] Comparative Example A2

[0339] In addition to using polyether block amide resin (Arkema Pebax) TM Rnew TM In addition to preparing PEBA membranes using 55R53 (Arkema), laminated membranes were prepared in the same manner as comparative example A1.

[0340] Comparative Example A3

[0341] Except for using a transparent polyimide-based film (TPI, SKC) with a thickness of 100 μm, the same procedure as step (1) of Example A1 was repeated to prepare a film with a hard coating.

[0342] The layer configurations of the membranes prepared above are summarized in Table 2 below.

[0343] Table 2

[0344] Example A1 Hard coating (5μm) / TPI (50μm) / PEBA 72R53 (50μm) Example A2 Hard coating (5μm) / TPI (50μm) / PEBA 55R53 (50μm) Comparative Example A1 TPI (50μm) / PEBA 72R53 (50μm) Comparative Example A2 TPI (50μm) / PEBA 55R53 (50μm) Comparative Example A3 Hard coating (5μm) / TPI (100μm)

[0345] Test Example A1: Nanoindentation Test

[0346] Nanoindentation tests were performed on the film samples prepared in the examples and comparative examples. Each film sample was cut to A4 size and stored at 25±5°C and 50±5% RH before testing, without additional pretreatment. Each film sample was then evaluated using a nanoindentation surface analyzer (FISCHERSCOPE HM2000, FISCHER). Specifically, each laminated film sample was placed on a glass test plate (Fischerscope part number 600-028) with a thickness of approximately 3T, serving as a sample holder, with the hard coating surface (or the base film surface if there was no hard coating) facing upwards (i.e., the indentation side). A nanoindentation test was then performed, in which a diamond tip was pressed downwards with a force of 30 mN for 15 seconds at room temperature, held (creep) for 5 seconds, and then lifted upwards. Vickers hardness (HV) and indentation hardness (H) were measured. IT ), recovery rate, and maximum indentation depth (h) under maximum force (30mN). max(30mN时) Nanoindentation testing was performed according to ISO 14577-1:2002(E) and 14577-2:2002(E) standards. Furthermore, the recovery rate was calculated using the following equation.

[0347] Recovery rate (%) = [(h max(30mN时) -h p ) / h max(30mN时) ]×100

[0348] Here, h max(30mN时) The maximum indentation depth (μm) is measured by pressing a 30mN force down on a hard-coated surface for 15 seconds and holding it (creep) for 5 seconds. p It is the indentation depth (μm) that has not recovered even after the force is released.

[0349] The results are shown in Table 3 below.

[0350] Table 3

[0351]

[0352] As can be seen from Table 3 above, the membranes in the examples exhibit excellent performance in terms of surface hardness and recoverability, while the membranes in the comparative examples are relatively poor in at least one of these properties.

[0353] Test Example A2: Optical Performance and Color

[0354] The optical properties and color of the membrane samples were measured. The average visible light transmittance of each membrane sample was measured according to ISO 13468, while haze was measured using a haze meter (NDH-5000W, Nippon Densho) according to ISO 14782. The yellow index (YI) of the membrane samples was measured using a spectrophotometer (UltraScanPRO, Hunter Associates Laboratory) at 10° with a d65 light source, according to ASTM-E313. Furthermore, the transparency color of the membrane samples was measured using a spectrophotometer (CM3700A, Minolta) with a D65 light source. The results are shown in Table 4 below.

[0355] Table 4

[0356] Example A1 88.50 1.34 0.69 93.95 -0.94 0.84 Example A2 85.16 3.31 0.71 93.93 -0.94 0.86 Comparative Example A1 82.98 1.17 1.82 92.66 -0.87 1.53 Comparative Example A2 81.76 3.30 1.85 92.71 -0.87 1.55 Comparative Example A3 84.36 0.85 1.88 92.54 -1.68 1.82

[0357] As can be seen from Table 4 above, the film in the examples performs excellently in terms of light transmittance, haze, and transparent color, while the film in the comparative examples is relatively poor in at least one of these characteristics.

[0358] B. Laminated films containing polyester-based films

[0359] Various laminates containing polyester-based films were prepared and evaluated.

[0360] Example B1

[0361] Step (1) Formation of hard coating

[0362] A hard coating composition having the composition shown in Table 5 was applied to one side of a 50 μm thick transparent polyester film (NRF, SKC) using a die-coating method. The film was then heat-treated at 60°C for 3 minutes to dry the solvent in the coating, and cured by UV light at a dose of 1 J to prepare a hard coating with a thickness of approximately 5 μm.

[0363] Table 5

[0364]

[0365] Step (2) Lamination of the elastic layer

[0366] polyether block amide resin (Arkema Pebax) TM Rnew TM 72R53 (Arkema) is fed into an extruder, melt-mixed at about 220°C, extruded into a single layer, and laminated with a base film that has formed a hard coating to prepare a laminated film. The laminated film has a 50 μm thick PEBA layer formed on the base film with the hard coating.

[0367] Example B2

[0368] In addition to the use of polyether block amide resin (ArkemaPebax) in step (2) of Example B1 TM Rnew TM In addition to preparing a PEBA membrane using 55R53 (Arkema), a laminate was prepared in the same manner as in Example B1.

[0369] Comparative Example B1

[0370] polyether block amide resin (Arkema Pebax) TM Rnew TM 72R53 (Arkema) is fed into an extruder, melt-mixed at about 220°C, extruded into a single layer, and laminated with a 50 μm thick transparent polyester base film (NRF, SKC) to prepare a laminated film, which has a 50 μm thick PEBA layer formed on the base film.

[0371] Comparative Example B2

[0372] In addition to using polyether block amide resin (Arkema Pebax) TM Rnew TM In addition to preparing PEBA membranes using 55R53 (Arkema), laminated membranes were prepared in the same manner as comparative example B1.

[0373] The layer configurations of the membranes prepared above are summarized in Table 6 below.

[0374] Table 6

[0375] Example B1 Hard coating (5μm) / NRF (50μm) / PEBA 72R53 (50μm) Example B2 Hard coating (5μm) / NRF (50μm) / PEBA 55R53 (50μm) Comparative Example B1 NRF(50μm) / PEBA 72R53(50μm) Comparative Example B2 NRF(50μm) / PEBA 55R53(50μm)

[0376] Test Example B1: Nanoindentation Test

[0377] Nanoindentation tests were performed on the film samples prepared in the examples and comparative examples. Each film sample was cut to A4 size and stored at 25±5°C and 50±5% RH before testing, without additional pretreatment. Each film sample was then evaluated using a nanoindentation surface analyzer (FISCHERSCOPE HM2000, FISCHER). Specifically, each laminated film sample was placed on a glass test plate (Fischerscope part number 600-028) with a thickness of approximately 3T, serving as a sample holder, with the hard coating surface (or the base film surface if there was no hard coating) facing upwards (i.e., the indentation side). A nanoindentation test was then performed by pressing a diamond tip downwards with a force of 30 mN for 15 seconds at room temperature, holding it (creep) for 5 seconds, and then lifting it upwards. The martensitic hardness (HV) and indentation modulus (E) were measured. IT ), restoration relationship (η) ITIndentation creep (C) IT ), maximum indentation depth (h) under 30mN force max(30mN时) Nanoindentation testing was performed according to ISO 14577-1:2002(E) and 14577-2:2002(E) standards. Furthermore, the recovery rate was calculated using the following equation.

[0378] Recovery rate (%) = [(h max(30mN时) -h p ) / h max(30mN时) ]×100

[0379] Here, h max(30mN时) The maximum indentation depth (μm) is measured by pressing a 30mN force down on a hard-coated surface for 15 seconds and holding it (creep) for 5 seconds. p It is the indentation depth (μm) that has not recovered even after the force is released.

[0380] The results are shown in Table 7 below.

[0381] Test Example B2: Optical Performance

[0382] The average visible light transmittance of each membrane sample was measured using a haze meter (NDH-5000W, Nippon Densho) according to ISO 13468 standard. The results are shown in Table 7 below.

[0383] Table 7

[0384]

[0385] As can be seen from Table 7 above, the membrane in the examples showed good performance in all indentation test results (HM, E...). IT η IT and C IT Both the film exhibit excellent performance in terms of light transmittance and hardness. Specifically, due to the combination of the polyester film with the hard coating and PEBA layer, the films in the examples possess high hardness (HM) during indentation, thus effectively dispersing the indentation force. These films also exhibit excellent recovery relationship (η) during indentation. IT ) and good resistance to permanent deformation (E IT As a result, despite indentation creep (C) IT The films exhibit large light transmittance but excellent recovery rate; therefore, even after folding, permanent deformation can be minimal. Furthermore, the films in the embodiments possess excellent light transmittance; thus, these films can be used as cover windows for mobile phones. In contrast, the films in the comparative examples are relatively poor in at least one test result.

Claims

1. A laminated film, the laminated film comprising: a base film; a rigid coating disposed on one side of the base film; and an elastic layer disposed on the other side of the base film, wherein, The elastic layer comprises polyether block amide; The laminated film is a laminated film used to cover the window in a foldable display device; and, The other side of the base film is the side of the base film facing the display panel included in the display device; When the hard coating surface is measured by nanoindentation test according to ISO 14577-1:2002(E) standard, the recovery rate of the laminate is 73.35% or higher; The recovery rate is calculated using the following equation: Recovery rate = [(h max（30mN时） - h p ) / h max（30mN时） ] × 100; Among them, h max（30mN时） The maximum indentation depth, measured in μm or h, is the maximum depth of an indentation formed by pressing a 30 mN force down on a hard-coated surface for 15 seconds and holding the indentation for 5 seconds. p It is the indentation depth that has not recovered even after the force is released, and its unit is μm. The unit of the recovery rate is %.

2. The laminated film as described in claim 1, wherein, When the surface of the hard coating is measured by nanoindentation test according to ISO 14577-1:2002(E) standard, the Vickers hardness of the laminate is 48 N / mm² or higher, and the indentation hardness is 505 N / mm² or higher.

3. The laminated film as described in claim 1, wherein, When the surface of a hard coating is measured by nanoindentation testing according to ISO 14577-1:2002(E) standard, the recovery rate of the laminate is 76% or higher, and the recovery rate is calculated by the following equation: Recovery rate = [(h max（30mN时） - h p ) / h max（30mN时） ] × 100; Among them, h max（30mN时） The maximum indentation depth is measured in μm when a 30mN force is applied downwards to the hard coating surface for 15 seconds and held for 5 seconds. hp is the indentation depth that does not recover even after the force is released, and its unit is μm. The recovery rate is measured in μm.

4. The laminated film as claimed in claim 1, wherein, The laminated film: When measured according to ISO 13468 standard, the average visible light transmittance is 80% or higher; When measured according to ISO 14782 standard, the haze is 4% or lower; The transmittance increase is calculated to be 2% or higher using the following equation: Transmittance increase = TT1 - TT2 Wherein, TT1 is the average visible light transmittance of the laminated film, in %, and TT2 is the average visible light transmittance of the film with the hard coating removed from the laminated film, in %, and the average visible light transmittance is measured under the same conditions according to ISO 13468 standard, and the unit of the transmittance increase is %.

5. The laminated film as claimed in claim 1, wherein, When measured at 10° using a D65 light source according to ASTM-E313, the yellow index of the laminate is 1.5 or lower, and a decrease in yellow index of 0.5 or higher is calculated using the following equation: Yellow Index Decrease = YI2 - YI1; Wherein, YI1 is the yellow index of the laminated film, and YI2 is the yellow index of the film with the hard coating removed from the laminated film. The yellow index is measured at 10° using a D65 light source under the same conditions according to the ASTM-E313 standard.

6. The laminated film as claimed in claim 1, wherein, When measured using a D65 light source, the L value of the transparent color of the laminate in the CIE Lab color coordinate system is... A value of 92 or higher, a Values ​​range from -2 to 1, b The value ranges from -1 to 2.

7. The laminated film as claimed in claim 1, wherein, The base film comprises a polymer film or ultrathin glass.

8. The laminated film as claimed in claim 1, wherein, The base film contains polyester-based resin.

9. The laminated film as claimed in claim 8, wherein, When the surface of the hard coating is measured by nanoindentation test according to ISO 14577-1:2002(E) standard, the martensitic hardness of the laminate is 175 N / mm² or higher.

10. The laminated film as claimed in claim 8, wherein, When the surface of a hard coating is measured by nanoindentation test according to ISO 14577-1:2002(E) standard, the indentation modulus of the laminate is 2900 MPa or higher.

11. The laminated film as claimed in claim 8, wherein, When the hard coating surface is measured by nanoindentation test according to ISO 14577-1:2002(E) standard, the recovery relationship of the laminate is 63.6% or higher.

12. The laminated film as claimed in claim 8, wherein, When the surface of a hard coating is measured by nanoindentation test according to ISO 14577-1:2002(E) standard, the indentation creep of the laminate is 3.5% or higher.

13. The laminated film as claimed in claim 8, wherein, When measured according to ISO 13468, the average visible light transmittance of the laminate is 85% or higher, with a transmittance increase of 3% or higher calculated by the following equation: Transmittance increase = TT1 - TT2; Wherein, TT1 is the average visible light transmittance of the laminated film, in %, and TT2 is the average visible light transmittance of the film with the hard coating removed from the laminated film, in %, and the average visible light transmittance is measured under the same conditions according to ISO 13468 standard, and the unit of the transmittance increase is %.

14. The laminated film as claimed in claim 1 or 8, wherein, The hard coating comprises at least one selected from the group consisting of urethane acrylate-based compounds, acrylate-based compounds, acrylic-based compounds, and epoxy acrylate-based compounds.

15. The laminated film of claim 14, wherein, The hard coating also contains fluorine-based compounds.

16. A display device, the display device comprising: a display panel; and a cover window disposed on the front side of the display panel. in, The cover window comprises: a base film; a rigid coating disposed on one side of the base film; and an elastic layer disposed on the other side of the base film. The elastic layer comprises polyether block amide; The other side of the base film is the side of the base film facing the display panel included in the display device; When the hard coating surface is measured by nanoindentation test according to ISO 14577-1:2002(E) standard, the recovery rate of the cover window is 73.35% or higher; The recovery rate is calculated using the following equation: Recovery rate = [(h max（30mN时） - h p ) / h max（30mN时） ] × 100; Among them, h max（30mN时） The maximum indentation depth, measured in μm or h, is the maximum depth of an indentation formed by pressing a 30 mN force down on a hard-coated surface for 15 seconds and holding the indentation for 5 seconds. p It is the depth of the indentation that has not recovered even after the force is released, and its unit is μm. The recovery rate is in units of %.

17. The display device as claimed in claim 16, wherein, The base film contains polyester-based resin.

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