Adhesive sheet and optical display device including same

Abstract

Disclosed are an adhesive sheet having bending characteristics and an optical display device including the same. The adhesive sheet according to the present invention is characterized by satisfying the following conditions: 1) 420 MPa < = EIT-30 DEG C < = 450 MPa, strain is measured by applying an axial force of 0.5 N and a force having a shear strength of 1800 Pa at 70 DEG C for 600 seconds, and when the strain when the force is removed for 600 seconds is residual strain, the residual strain is 5% or less. In the condition 1), EIT-30 DEG C represents the elastic modulus measured according to the measurement method 1. Measurement method 1: Measurement is performed by adhering the adhesive sheet to glass, increasing a load to 200 mN at a predetermined speed and applying pressure for 10 seconds at-30 DEG C with a ball indenter having a diameter of 2 mm, holding for 5 seconds under a load of 200 mN, and then reducing the load from 200 mN to 0 mN at a predetermined speed within 10 seconds.

Description

Technical Field

[0001] The present invention relates to an adhesive sheet having bending characteristics and an optical display device including the same. Background Art

[0002] In recent years, with the rapid development of information and communication technology and the expansion of the market scale, the demand for optical display devices such as display devices has been increasing. Representative examples of such optical display devices include liquid crystal display elements, plasma display panels, and organic light emitting diodes.

[0003] On the other hand, an adhesive sheet is provided at the lower part of the display device to protect the display device from external forces and prevent the generation of static electricity. In recent years, as the application range of display devices has gradually expanded, reliability in high-temperature and low-temperature usage environments has also been considered an essential characteristic, and with the emergence of flexible and foldable display screens, the softness or flexibility of the thin sheet also needs to be improved to ensure the durability of the product.

[0004] Therefore, it is necessary to develop an adhesive sheet that can exhibit reliability under different temperature conditions and external force applications.

[0005] As described above, flexible optical display devices are recently being developed, and in particular, the adhesive sheets used therein require excellent bending characteristics. Summary of the Invention

[0006] An object of the present invention is to provide an adhesive sheet having bending characteristics.

[0007] Moreover, an object of the present invention is to provide an adhesive sheet that has a low elastic modulus at low temperatures, maintains the elastic modulus at normal temperatures, and has high creep and low residual strain.

[0008] The object of the present invention is not limited to the above object, and other objects and advantages of the present invention not mentioned can be understood through the following description and more clearly understood through the embodiments of the present invention. And it is obvious that the objects and advantages of the present invention can be achieved by the methods and combinations represented in the claims of the patent application.

[0009] The adhesive sheet of the present invention satisfies the condition 1) 420 MPa ≤ EIT -30℃≤450 MPa. The strain is measured by applying an axial force of 0.5 N and a force of 1800 Pa for 600 seconds at 70 °C. When the strain at 600 seconds after removing the force is the residual strain, the residual strain is 5%.

[0010] In the above condition 1), EIT -30℃ represents the elastic modulus measured according to Measuring Method 1.

[0011] Measuring Method 1:

[0012] By attaching the adhesive sheet to glass, using a ball indenter with a diameter of 2 mm at -30 °C, increasing the load to 200 mN at a specified speed and applying pressure for 10 seconds, after maintaining the load at 200 mN for 5 seconds, within 10 seconds, the load is reduced from 200 mN to 0 mN at a specified speed for measurement.

[0013] In the adhesive sheet, when the strain at 600 seconds after applying an axial force of 0.5 N and a shear strength of 1800 Pa at 70 °C is creep, the creep can be 18% or more.

[0014] And, the adhesive sheet can satisfy the condition 2) 286 MPa ≤ EIT 25℃ ≤ 325 MPa. In the above condition 2), EIT 25℃ represents the elastic modulus measured according to the above Measuring Method 1.

[0015] The adhesive sheet may contain an acrylic resin and an isocyanate adduct type curing agent.

[0016] The acrylic resin may contain one or more acrylic monomers such as an unsubstituted linear or branched (meth)acrylic acid alkyl ester monomer with 1 to 20 carbon atoms, a (meth)acrylic acid monomer containing a hydroxyl group and a hydrocarbon group with 1 to 20 carbon atoms, and 2-(2-ethoxyethoxy)ethyl acrylate monomer.

[0017] Relative to the total amount of 100 weight percentages, the acrylic resin may contain 13.5 to 22.5 weight percentages of 2-(2-ethoxyethoxy)ethyl acrylate monomer.

[0018] Relative to 100 parts by weight of the acrylic resin, the adhesive sheet may contain 0.006 to 0.014 parts by weight of the isocyanate adduct type curing agent.

[0019] The display component of the present invention is characterized in that it includes: an optical film; and the adhesive sheet according to claim 1, disposed on at least one surface of the optical film.

[0020] Effect of the Invention

[0021] The adhesive sheet of the present invention has bending characteristics.

[0022] In particular, it has a low elastic modulus at low temperatures, while maintaining the elastic modulus at room temperature, and has high creep and low residual strain.

[0023] In addition to the above effects, the specific effects of the present invention will be described while explaining the following specific implementation methods. Description of the Drawings

[0024] Figure 1 It is a cross-sectional view showing the display component of the present invention.

[0025] Explanation of Reference Numerals:

[0026] 10: Adhesive sheet;

[0027] 20: Optical film. Detailed Description of the Invention

[0028] The above-mentioned objects, features, and advantages will be described in detail with reference to the drawings later. Thus, those of ordinary skill in the technical field to which the present invention pertains can easily implement the technical idea of the present invention. When describing the present invention, if it is determined that the specific description of the well-known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals are used to denote the same or similar structural elements.

[0029] Hereinafter, setting any structure "above (or below)" a structural element or "on (or under)" a structural element means that the any structure is set in contact with the upper surface (or lower surface) of the structural element, and other structures may be interposed between the structural element and the any structure set on (or under) the structural element.

[0030] And when it is described that a certain structural element is "connected", "joined", or "coupled" to other structural elements, the plurality of structural elements may be directly connected or coupled to each other, but it should be understood that other structural elements may be "interposed" between the structural elements, or the structural elements may be "connected", "joined", or "coupled" through other structural elements.

[0031] Hereinafter, the adhesive sheet and the optical display device including the same according to some embodiments of the present invention will be described.

[0032] In the present invention, the adhesive sheet refers to a structure including a sheet-like or film-like adhesive layer formed of an adhesive composition.

[0033] As the adhesive sheet of the present invention is an adhesive sheet for a foldable backplane and requires bending characteristics, it is crucial to have soft characteristics.

[0034] For this reason, a monomer capable of imparting softness to the adhesive sheet is selected, but there are the following problems: the elastic modulus at low temperature is not sufficiently reduced, or although the elastic modulus at low temperature is reduced, the residual strain increases.

[0035] For this reason, the present inventor introduced 2-(2-ethoxyethoxy)ethyl acrylate monomer as a new monomer into the acrylic resin, reduced the low-temperature elastic modulus and residual strain, and ensured high creep, thereby confirming that the bending characteristics at low temperature are excellent, no cracks are generated, and no permanent deformation occurs.

[0036] The adhesive sheet of the present invention is characterized in that it satisfies the condition 1) 420 MPa ≤ EIT -30M ≤ 450 MPa. The strain is measured by applying an axial force of 0.5 N and a force of 1800 Pa at 70 °C for 600 seconds. When the strain when the force is removed after 600 seconds is the residual strain, the residual strain is 5% or less.

[0037] Preferably, the adhesive sheet can satisfy the condition 1) 428 MPa ≤ EIT -30℃ ≤ 449 MPa.

[0038] In the above condition 1), EIT -30℃ represents the elastic modulus measured according to Measurement Method 1.

[0039] Measurement Method 1:

[0040] By attaching the adhesive sheet to glass, using a ball indenter with a diameter of 2 mm at -30 °C, increasing the load to 200 mN at a specified speed and applying pressure for 10 seconds, after maintaining the load at 200 mN for 5 seconds, within 10 seconds, the load is reduced from 200 mN to 0 mN at a specified speed for measurement.

[0041] The elastic modulus is obtained according to the nano-indentation method for measuring the surface and surface physical properties. The nano-indentation method in this specification refers to the method of applying a load through a nano indenter and evaluating its physical properties according to Measurement Method 1.

[0042] The elastic modulus represents the coefficient of relative length change of a material when subjected to a deforming force. If the elastic modulus is high, the stiffness increases, resulting in a decrease in bending characteristics (bending reliability). If the elastic modulus is too low, the protective effect on the adherend material may be reduced.

[0043] Generally, if the elastic modulus is low, the residual strain will increase. In the present invention, by reducing the elastic modulus while also reducing the residual strain, there is an effect of preventing the occurrence of permanent deformation of the bending characteristic.

[0044] For the residual strain (recovery), the adhesive sheet of the present invention can be 5% or less, preferably, it can be 0.3 - 3%, and more preferably, it can be 0.3 - 1%.

[0045] The residual strain can be measured by using a rheometer (ARES G2, TA Instruments) to manufacture a measurement sample according to the following method.

[0046] Apply the composition to a light release liner (SKC, SG31) with a release force of 30 gf, and laminate it to a heavy release liner (SKC HT&M, RT81N) with a release force of 100 gf at room temperature using a roll laminator to bond the layers to a thickness of 1 mm.

[0047] Subsequently, cure the adhesive layer at 50 °C for 48 hours to manufacture a sample for measuring the residual strain.

[0048] Punch the manufactured sample into a circle with a diameter of 8 mm. After removing the light release liner, attach it to a parallel plate with a diameter of 8 mm, and then remove the heavy release liner.

[0049] The adhesive sheet of the present invention can prevent permanent deformation by satisfying the above - mentioned limited residual strain at a high temperature of 70 °C. Due to its excellent recovery force, the problem of cracks generated in the display component can be minimized.

[0050] As described above, since the residual strain of the adhesive sheet of the present invention at 70 °C is 5% or less, it has the effect of being conducive to exhibiting the bending characteristics required for the display. Even if the adherend undergoes multiple deformations, excellent protection effects can be exhibited.

[0051] Generally, the elastic modulus shows a similar trend at low temperature and room temperature. Therefore, as the low - temperature elastic modulus decreases, the room - temperature elastic modulus also decreases.

[0052] If the room - temperature elastic modulus decreases, the occurrence of flash steaming defects will increase during punching, thereby reducing the processability of the process.

[0053] Therefore, preferably, the room - temperature elastic modulus is controlled together with the low - temperature elastic modulus.

[0054] Different from the general trend, the adhesive sheet of the present invention reduces the low - temperature elastic modulus at - 30 °C while maintaining the room - temperature elastic modulus, thereby preventing cracks caused by bending characteristics at low temperature.

[0055] From this perspective, the adhesive sheet can meet the condition 2) 286 MPa ≤ EIT 25℃ ≤ 325 MPa. In the condition 2), EIT 25℃ represents the elastic modulus measured according to the measurement method 1 at 25°C.

[0056] In the adhesive sheet, when the strain is creep when an axial force of 0.5 N and a force of 1800 Pa at 70°C are applied to the adhesive sheet for 600 seconds, the creep can be 18% or more. Preferably, the creep can be 18 - 25%.

[0057] The greater the creep, the smaller the force required to achieve deformation, which is beneficial for ensuring bending characteristics.

[0058] This adhesive sheet of the present invention, as a cured product of the adhesive composition, may contain an acrylic resin and an isocyanate adduct type curing agent.

[0059] The acrylic resin may contain one or more acrylic monomers such as an unsubstituted linear or branched (meth)acrylic acid alkyl ester monomer having 1 to 20 carbon atoms, a (meth)acrylic acid monomer containing a hydroxyl group and a hydrocarbon group having 1 to 20 carbon atoms, and 2-(2-ethoxyethoxy)ethyl acrylate monomer.

[0060] The unsubstituted linear or branched (meth)acrylic acid alkyl ester monomer having 1 to 20 carbon atoms may contain one or more of (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, (meth)acrylic acid n-butyl ester, (meth)acrylic acid tert-butyl ester, (meth)acrylic acid isobutyl ester, (meth)acrylic acid pentyl ester, (meth)acrylic acid hexyl ester, (meth)acrylic acid heptyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid octyl ester, (meth)acrylic acid isooctyl ester, (meth)acrylic acid nonyl ester, (meth)acrylic acid decyl ester, and (meth)acrylic acid lauryl ester.

[0061] Among the unsubstituted linear or branched (meth)acrylic acid alkyl ester monomers having 1 to 20 carbon atoms, preferably, an acrylic monomer having 8 - 12 carbon atoms may be included. For example, (meth)acrylic acid 2-ethylhexyl ester may be included.

[0062] The hydrocarbon group having 1 to 20 carbon atoms may be, for example, a methacrylate having an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 5 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0063] Specifically, the hydroxy-containing (meth)acrylic monomer may include one or more of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, 1-chloro-2-hydroxypropyl (meth)acrylate, diethylene glycol mono(meth)acrylate, 1,6-hexanediol mono(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, neopentyl glycol mono(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolethane di(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 4-hydroxycyclopentyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, and cyclohexanedimethanol mono(meth)acrylate.

[0064] Even among (meth)acrylic monomers containing a hydroxyl group and a hydrocarbon group having 1 to 20 carbon atoms, preferably, it may include one or more of 2-hydroxybutyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate.

[0065] In the acrylic resin, the content of one or more acrylic monomers of an unsubstituted linear or branched (meth)acrylic alkyl ester monomer having 1 to 20 carbon atoms and a (meth)acrylic monomer containing a hydroxyl group and a hydrocarbon group having 1 to 20 carbon atoms may be 77.5 to 86.5% by weight.

[0066] Specifically, an unsubstituted linear or branched (meth)acrylic alkyl ester monomer having 1 to 20 carbon atoms and a (meth)acrylic monomer containing a hydroxyl group and a hydrocarbon group having 1 to 20 carbon atoms may be included simultaneously. In this case, the content of the unsubstituted linear or branched (meth)acrylic alkyl ester monomer having 1 to 20 carbon atoms may be higher than the content of the (meth)acrylic monomer containing a hydroxyl group and a hydrocarbon group having 1 to 20 carbon atoms.

[0067] The content of the unsubstituted linear or branched (meth)acrylic alkyl ester monomer having 1 to 20 carbon atoms may be 62.5 to 83.5% by weight, and the content of the (meth)acrylic monomer containing a hydroxyl group and a hydrocarbon group having 1 to 20 carbon atoms may be 3 to 15% by weight.

[0068] If the content of the (meth)acrylic monomer containing a hydroxyl group and a hydrocarbon group having 1 to 20 carbon atoms is less than 3% by weight, problems such as a decrease in hardness and processability may occur due to the reduction of functional groups. On the contrary, if the content of the (meth)acrylic monomer containing a hydroxyl group and a hydrocarbon group having 1 to 20 carbon atoms exceeds 15% by weight, problems such as an increase in hardness and a decrease in adhesion may occur.

[0069] The acrylic resin that constitutes the adhesive sheet of the present invention contains 2-(2-ethoxyethoxy)ethyl acrylate monomer, so that it can exhibit a low elastic modulus at -30°C while maintaining the elastic modulus at room temperature without reduction, thereby having the effect of preventing permanent deformation.

[0070] Structural formula 1:

[0071]

[0072] As the content of 2-(2-ethoxyethoxy)ethyl acrylate monomer increases, the elastic modulus at -30°C and room temperature shows a decreasing trend.

[0073] From this perspective, relative to the total amount of 100 weight percentages, the acrylic resin may contain 13.5 to 22.5 weight percentages of 2-(2-ethoxyethoxy)ethyl acrylate monomer.

[0074] The acrylic resin contains 13.5 to 22.5 weight percentages of 2-(2-ethoxyethoxy)ethyl acrylate monomer, so that it is beneficial to meet the condition 1) 420 MPa ≤ EIT

[0075] ≤ 450 MPa and the condition 2) 286 MPa ≤ EIT -30℃ ≤ 325 MPa. 25℃

[0076] In order to impart bending characteristics to the adhesive sheet, preferably, an isocyanate adduct type curing agent is included in the curing agent.

[0077] The isocyanate adduct type curing agent may contain one or more of xylene diisocyanate adduct and toluene diisocyanate adduct. Preferably, it may contain xylene diisocyanate adduct and toluene diisocyanate adduct.

[0078] The xylene diisocyanate adduct curing agent can be represented by Structural formula 2.

[0079] Structural formula 2:

[0080]

[0081] In Structural formula 2, R can be hydrogen, an alkyl group with 1 to 20 carbon atoms, an aryl group, a heteroaryl group, or a substituted aryl group. For example, R is CH2CH3.

[0082] The toluene diisocyanate adduct curing agent can be represented by Structural formula 3.

[0083] Structural formula 3: ​

[0084]

[0085] In Structural Formula 3, R is hydrogen or an alkyl, aryl, heteroaryl or substituted aryl group having 1 to 20 carbon atoms. For example, R is CH2CH3.

[0086] Relative to 100 parts by weight of the acrylic resin, the adhesive sheet may contain 0.006 to 0.014 parts by weight of an isocyanate adduct type curing agent. Preferably, it may contain 0.006 to 0.01 parts by weight.

[0087] The content of the isocyanate adduct type curing agent satisfies 0.006 to 0.014 parts by weight, thereby having the effect of being beneficial to ensuring the low-temperature elastic modulus, room-temperature elastic modulus, creep and residual strain.

[0088] If the content of the isocyanate adduct type curing agent is less than 0.006 parts by weight, the residual strain may be greater than 5%, resulting in permanent deformation of the adhesive sheet and possibly a decrease in the low-temperature elastic modulus and room-temperature elastic modulus. On the contrary, if the content of the isocyanate adduct type curing agent is greater than 0.014 parts by weight, the creep may be less than 18%, and the low-temperature elastic modulus and room-temperature elastic modulus increase significantly.

[0089] The adhesive sheet may contain various additives commonly used in the field of adhesive layers, such as a leveling agent, a crosslinking aid, a plasticizer, a softening agent, a filler, an antistatic agent, an anti-aging agent, an ultraviolet absorber, an antioxidant and a light stabilizer, as needed.

[0090] These additives can be used according to conventional methods with existing well-known additives, and the adhesive sheet can be manufactured by curing an adhesive composition containing these solid additives.

[0091] The display component of the present invention is characterized in that it includes an optical film 20 and an adhesive sheet 10 provided on at least one surface of the optical film.

[0092] As long as it is a film used in the optical field such as a display screen, it can be unrestrictedly applied to the optical film. For example, the optical film may include a touch panel, a window, a polarizing plate, a color filter, a retardation film, an elliptical polarizing film, a reflective film, an antireflection film, a compensation film, a brightness enhancement film, an alignment film, a light diffusion film, a glass antiscattering film, a surface protection film, an OLED element barrier layer, a plastic liquid crystal display (LCD) substrate, an indium tin oxide (ITO) film, a fluorinated tin oxide (FTO) film, an aluminum-doped zinc oxide (AZO) film, a carbon nanotube (CNT) film, a silver nanowire film, a graphene film, and other transparent electrode films.

[0093] Specific embodiments of the adhesive sheet and the optical display device including the same are observed as follows.

[0094] 1. Manufacture of the adhesive sheet and the optical display device including the same

[0095] As shown in Table 1 below, polyacrylic monomers were copolymerized according to the ratios (weight percentages) of Test Pieces 1 to 26 to prepare an acrylic main resin having a hydroxyl functional group.

[0096] 100 parts by weight of the acrylic main resin, 20 parts by weight of ethyl acetate as a solvent, 0.1 part by weight of an ionic liquid (ammonium salt) as an antistatic agent, and 0.002 to 0.016 parts by weight of a curing agent were mixed at 25°C to prepare an adhesive composition.

[0097] Among them, the curing agent is a curing agent according to Structural Formula 2 and Structural Formula 3, and R is CH2CH3.

[0098] After the adhesive composition was coated in a thin film form on the upper surface of a polyethylene terephthalate substrate coated with PEDOT / PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) in a thin film form, the release surface of a release film subjected to a silicon release treatment was adhered to the coated adhesive composition, and then cured at 50°C for 48 hours to manufacture the adhesive sheets of Test Pieces 1 to 26.

[0099] 2-EHA: 2-Ethyl hexyl acrylate

[0100] 2-HEA: 2-Hydroxyl Ethyl Acrylate

[0101] 4-HBA: 4-Hydroxy butyl acrylate

[0102] EOEOA: 2-(2-Ethoxyethoxy)ethyl Acrylate

[0103] NVP: N-Vinylpyrrolidone

[0104] ID: Isodecyl acrylate

[0105] Table 1

[0106]

[0107] 2. Physical property evaluation methods and their results

[0108] Creep

[0109] When the strain when applying an axial force of 0.5 N and a force of 1800 Pa for 600 seconds at 70°C to the adhesive sheet is creep, the creep should reach 18% or more.

[0110] Residual strain

[0111] Using a rheometer (ARES G2, TA Instruments), coat the composition on a light release liner (SKC, SG31) with a release force of 30 gf, and laminate it to a heavy release liner (SKC HT&M, RT81N) with a release force of 100 gf at room temperature using a roller laminator to laminate the adhesive layer to a thickness of 1 mm.

[0112] Subsequently, cure the adhesive layer at 50°C for 48 hours to produce a sample for measuring residual strain. Punch the produced sample into a circle with a diameter of 8 mm, remove the light release liner, attach it to a parallel plate with a diameter of 8 mm, remove the heavy release liner, and produce an adhesive sheet.

[0113] Measure the strain by applying an axial force of 0.5 N and a force of 1800 Pa for 600 seconds at 70°C to the adhesive sheet. When the strain when removing the force after 600 seconds is the residual strain, the residual strain should be 5% or less.

[0114] EIT -30℃ and EIT 25℃

[0115] Measurement method 1:

[0116] By attaching the adhesive sheet to glass, at -30°C and 25°C respectively, using a ball indenter with a diameter of 2 mm, increasing the load to 200 mN at a specified speed and applying pressure for 10 seconds, after the adhesive sheet is held under a 200 mN load for 5 seconds, within 10 seconds, the load is decreased from 200 mN to 0 mN at a specified speed for measurement.

[0117] Table 2

[0118]

[0119]

[0120] Specimen 1, as a specimen containing 2-EHA and 4-HBA in an acrylic resin, the EIT -30℃ and EIT 25℃ values showed excessively high values.

[0121] Specimens 2 and 3, as specimens containing 2-EHA, 4-HBA, and EOEOA in an acrylic resin but with the content of EOEOA exceeding 13.5 wt% - 22.5 wt%, although they met creep, they did not meet EIT -30℃ 、EIT 25℃ and at least one of residual strain.

[0122] Specimens 4 to 6, as specimens containing 2-EHA, 4-HBA, and EOEOA in an acrylic resin, since they met all the composition ratios, they showed the results to be achieved by the present invention in terms of EIT -30℃ 、EIT 25℃ 、creep, and residual strain items.

[0123] Specimens 7 to 10, as specimens containing 2-EHA and 4-HBA in an acrylic resin and further containing NVP or ID, although they met creep and residual strain, they did not meet EIT -30℃ and EIT 25℃ in at least one of them.

[0124] Specimens 11 to 24, as specimens not containing EOEOA in an acrylic resin and containing 2-HEA and / or 4-HBA or with the content of 4-HBA exceeding the standard, did not meet EIT -30℃ 、EIT 25℃ 、creep, and at least one of residual strain.

[0125] In particular, the creep of Specimens 13 to 17, Specimen 19, Specimens 23, and 24 exceeded 25%.

[0126] The specimens 25 and 26, as specimens with the content of the curing agent exceeding 0.006 parts by weight to 0.014 parts by weight, did not meet EIT -30℃ , EIT 25℃ , creep, and at least one of the residual strains.

[0127] The present invention has been described above, but the present invention is not limited to the embodiments disclosed in this specification. Obviously, those of ordinary skill in the art can make various modifications within the scope of the technical idea of the present invention. In addition, in the above description of the embodiments of the present invention, even if the effects and functions produced by the structure of the present invention are not explicitly described and recorded, the effects predictable by the structure should also be recognized.

Claims

1. A bonding sheet, characterized in that: Satisfy the conditions 1) 420MPa≤EIT -30℃ ≤450MPa, The strain is measured by applying an axial force of 0.5N and a shear strength of 1800Pa at 70°C for 600 seconds. When the strain after removing the force for 600 seconds is the residual strain, the residual strain is less than 5%. In the condition 1), EIT -30℃ represents the elastic modulus measured according to measurement method 1, Measurement method 1: The bonding sheet is attached to glass, and a ball indenter with a diameter of 2 mm is used at -30°C to increase the load to 200 mN at a specified speed and apply pressure for 10 seconds. After maintaining the load at 200 mN for 5 seconds, the load is reduced from 200 mN to 0 mN at a specified speed within 10 seconds for measurement.

2. The bonding sheet according to claim 1, characterized in that: When the strain when an axial force of 0.5 N and a force having a shear strength of 1800 Pa at 70° C. are applied for 600 seconds is considered creep, the creep is 18% or more.

3. The bonding sheet according to claim 1, characterized in that: Satisfy condition 2) 286MPa≤EIT 25℃ ≤325MPa, In the condition 2), EIT 25℃ represents the elastic modulus measured according to the measurement method 1.

4. The bonding sheet according to claim 1, characterized in that: The bonding sheet comprises an acrylic resin and an isocyanate adduct type curing agent.

5. The bonding sheet according to claim 4, characterized in that: The acrylic resin includes an unsubstituted linear or branched (meth)acrylic acid alkyl ester monomer having 1 to 20 carbon atoms, one or more acrylic acid monomers selected from the group consisting of a hydroxyl group and a hydrocarbon group having 1 to 20 carbon atoms, and a 2-(2-ethoxyethoxy)ethyl acrylate monomer.

6. The bonding sheet according to claim 5, characterized in that: The acrylic resin includes 13.5 to 22.5 weight percent of 2-(2-ethoxyethoxy)ethyl acrylate monomer relative to 100 weight percent of the total amount.

7. The bonding sheet according to claim 4, characterized in that: The adhesive sheet includes 0.006 to 0.014 parts by weight of an isocyanate adduct curing agent relative to 100 parts by weight of an acrylic resin.

8. A display component, characterized in that: include: Optical films; as well as The adhesive sheet according to claim 1, disposed on at least one surface of the optical film.

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