Optical laminate and image display device having the same

Abstract

The present invention provides an optical laminate and an image display device having the same, the optical laminate comprising: a glass substrate; a primer layer formed on the glass substrate to cover an upper surface and side surfaces of the glass substrate; a base resin layer formed on the primer layer to cover an upper surface and side surfaces of the primer layer; and a functional coating layer formed on the base resin layer, in which the glass substrate is ultra-thin glass having a thickness of less than 100 [mu] m, and the optical laminate has a pencil hardness of 2H or more throughout the optical laminate, and the ratio of the total thickness of the primer layer, the base resin layer and the functional coating layer to the thickness of the glass substrate is controlled within a certain range. The optical laminate according to the present invention has excellent pencil hardness characteristics while securing bending resistance without causing curl, thereby providing excellent processability, and preventing the glass substrate from breaking due to external impact, and preventing the glass fragments from being broken even if the glass substrate is broken.

Description

Technical Field

[0001] The present invention relates to an optical laminate and an image display device having the same. More specifically, the present invention relates to an optical laminate of a glass substrate, which has excellent pencil hardness while ensuring bending resistance without causing curling, thereby providing excellent workability, and prevents the glass substrate from being broken by external impact, and even if broken, prevents the glass from being shattered into pieces, and an image display device having the same. Background Art

[0002] Recent advances in display technology have led to the development of foldable, rollable, and stretchable displays. To protect these various types of displays, ultra-thin glass (UTG) with improved flexible properties is being actively researched.

[0003] These ultra-thin glasses, due to their flexible nature, require excellent bending strength for use in various types of displays. Furthermore, to enhance display quality, surface roughness needs to be improved.

[0004] Generally, in order to reduce the possibility of scratches on the glass surface of the window glass during use of the display and the possibility of breakage due to dropping during use, chemical strengthening using ion substitution is used to enhance the strength of the window glass used in mobile displays.

[0005] For example, Korean Patent Publication No. 10-1999-0042313 discloses a method for strengthening glass for displays.

[0006] However, ultra-thin glass is so thin that even with this chemical strengthening process, a protective film with a soft adhesive is required to prevent it from breaking. However, this leads to problems such as the hardness of the pencil being weakened and leaving marks when using the pen.

[0007] Alternatively, when a coating of a resin material is formed on ultrathin glass to prevent breakage or improve surface hardness, shrinkage stress caused by hardening of the coating causes curling, which reduces workability.

[0008] Furthermore, even if a coating is formed on ultra-thin glass, the sides are not protected, so if an external impact is applied to the sides during the manufacturing process, the glass substrate may break and the glass fragments may shatter. Summary of the Invention

[0009] [Technical Issues]

[0010] An object of the present invention is to provide an optical laminate having a glass substrate having excellent pencil hardness characteristics while ensuring bending resistance without causing curling, thereby providing excellent workability, and preventing the glass substrate from being broken by external impact and preventing the breakage of glass fragments even if broken.

[0011] Another object of the present invention is to provide an image display device having an optical laminate.

[0012] [Technical solution]

[0013] According to one aspect, the present invention provides an optical stack comprising:

[0014] Glass substrate;

[0015] a primer layer formed on the glass substrate to cover the upper surface and side surfaces of the glass substrate;

[0016] a base resin layer formed on the primer layer to cover the upper surface and side surfaces of the primer layer; and

[0017] A functional coating is formed on the base resin layer, wherein

[0018] The glass substrate is ultra-thin glass with a thickness of less than 100 μm.

[0019] The optical stack has a pencil hardness of 2H or greater throughout the optical stack, and

[0020] The optical stack satisfies the following equation (1):

[0021] [Equation 1]

[0022] 0.1≤d2 / d1≤0.4

[0023] in,

[0024] d1 is the thickness of the glass substrate, and

[0025] d2 is the total thickness of the primer layer, base resin layer and functional coating layer.

[0026] In one embodiment of the present invention, the primer layer may be formed to cover the entire surface of the glass substrate.

[0027] In one embodiment of the present invention, the base resin layer may be formed to cover the entire surface of the primer layer.

[0028] The optical stack according to one embodiment of the present invention may have a total thickness of less than 120 μm.

[0029] In one embodiment of the present invention, the primer layer may be formed of a composition for forming a primer layer, the composition including at least one of a polyurethane resin and a polyester resin.

[0030] In one embodiment of the present invention, the primer layer may be formed of a composition for forming a primer layer, the composition including an aqueous polyurethane resin and a stabilizer, and the stabilizer may include a primary thermal stabilizer and a secondary thermal stabilizer.

[0031] In one embodiment of the present invention, the primary thermal stabilizer may be at least one selected from phenolic thermal stabilizers and amine thermal stabilizers, and the secondary thermal stabilizer may be at least one selected from phosphorus thermal stabilizers and sulfur thermal stabilizers.

[0032] In one embodiment of the present invention, the base resin layer may be formed of a composition for forming a base resin layer, the composition including at least one resin of a polyimide resin and a polyamideimide resin.

[0033] In one embodiment of the present invention, the base resin layer may have an elastic modulus of 3.3 GPa to 5.2 GPa.

[0034] In one embodiment of the present invention, the functional coating may be a hard coating.

[0035] In one embodiment of the present invention, the hard coating layer may be formed of a hard coating layer composition comprising a light-transmitting resin, a compound containing a fluorine-based UV-curable functional group, a photoinitiator, and a solvent.

[0036] According to another aspect, the present invention provides an image display device including the optical laminate.

[0037] According to yet another aspect, the present invention provides a window for a flexible display having the optical laminate.

[0038] According to another aspect, the present invention provides a polarizing plate having the optical laminate.

[0039] According to yet another aspect, the present invention provides a touch sensor having the optical stack.

[0040] According to another aspect, the present invention provides a transmittance-adjustable optical stack having the optical stack.

[0041] According to yet another aspect, the present invention provides a smart window having an optical stack with adjustable light transmittance.

[0042] [Beneficial Effects]

[0043] An optical laminate according to one embodiment of the present invention has protected side surfaces to prevent the glass substrate from breaking due to external impact, and even if it does break, it prevents the glass from shattering. Furthermore, the optical laminate according to the present invention has a structure in which a primer layer, a base resin layer, and a functional coating layer are sequentially laminated on ultrathin glass. This allows the ratio of the total thickness of the primer layer, base resin layer, and functional coating layer to the thickness of the glass substrate to be controlled within a certain range, resulting in excellent pencil hardness characteristics and ensuring bending resistance without causing curling, thereby providing excellent workability. Specifically, the optical laminate according to one embodiment of the present invention exhibits a pencil hardness of 2H or greater and leaves no marks when used with a pen. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic cross-sectional view of an optical laminate according to an embodiment of the present invention.

[0045] Figure 2 is a schematic cross-sectional view of an optical layered body according to another embodiment of the present invention. DETAILED DESCRIPTION

[0046] Hereinafter, the present invention will be described in more detail.

[0047] One embodiment of the present invention relates to an optical laminate, comprising:

[0048] Glass substrate;

[0049] a primer layer formed on the glass substrate to cover the upper surface and side surfaces of the glass substrate;

[0050] a base resin layer formed on the primer layer to cover the upper surface and side surfaces of the primer layer; and

[0051] A functional coating is formed on the base resin layer, wherein

[0052] The glass substrate is ultra-thin glass with a thickness of less than 100 μm.

[0053] The optical stack has a pencil hardness of 2H or greater throughout the optical stack, and

[0054] The optical stack satisfies the following equation (1):

[0055] [Equation 1]

[0056] 0.1≤d2 / d1≤0.4

[0057] in,

[0058] d1 is the thickness of the glass substrate, and

[0059] d2 is the total thickness of the primer layer, the base resin layer and the functional coating layer.

[0060] According to one embodiment of the present invention, the optical stack has a d2 / d1 value of 0.1 to 0.4, preferably 0.1 to 0.3.

[0061] In the present invention, d1 is the thickness of the glass substrate, and d2 is the total thickness of the primer layer, the base resin layer, and the functional coating layer.

[0062] Specifically, in the case where a primer layer is formed on a glass substrate to cover only the upper surface and side surfaces of the glass substrate, and a base resin layer is formed on the primer layer to cover only the upper surface and side surfaces of the primer layer, d2 is the total thickness of the primer layer, the base resin layer, and the functional coating layer present on the upper surface of the glass substrate.

[0063] When having a structure in which a primer layer is formed on a glass substrate to cover the entire surface of the glass substrate and a base resin layer is formed on the primer layer to cover the entire surface of the primer layer, d2 is the sum of the total thickness of the primer layer, the base resin layer and the functional coating layer present on the upper surface of the glass substrate and the total thickness of the primer layer and the base resin layer present on the lower surface of the glass substrate.

[0064] If the d2 / d1 value is less than 0.1, the hardness characteristics may be reduced to the extent that the lower glass substrate may break when measuring the pencil hardness characteristics, and if the d2 / d1 value exceeds 0.4, the curling characteristics may be poor.

[0065] According to one embodiment of the present invention, the optical stack has a pencil hardness of 2H or higher, preferably 4H or higher throughout the entire optical stack.

[0066] Pencil hardness is defined as the hardness of a pencil used in a test performed when, after fixing the optical laminate with the functional coating layer placed thereon, the pencil hardness test is repeated five times with a load of 750 gf over a length of 1 cm on the functional coating side, and no obvious abnormality such as scratches is recognized at least four times during the test. For example, if a pencil with a hardness of 2H is used to perform five test exercises and no external abnormality is recognized at least four times, the material has a pencil hardness of 2H or higher.

[0067] If the pencil hardness of the entire optical stack is less than 2H, the pen may leave an indentation mark, or the indentation may take a long time to recover.

[0068] The optical stack according to one embodiment of the present invention may have a total thickness of less than 120 μm, for example, at least 35 μm and less than 120 μm. If the total thickness of the optical stack is 120 μm or more, it may be difficult to ensure bending resistance.

[0069] An optical laminate according to one embodiment of the present invention has a structure in which a primer layer is formed on a glass substrate to cover the upper surface and side surfaces of the glass substrate, and a base resin layer is formed on the primer layer to cover the upper surface and side surfaces of the primer layer, thereby preventing the glass substrate from being broken due to external impact, particularly external impact applied to the side surfaces of the glass substrate, and preventing glass fragments from being shattered even if the glass substrate is broken.

[0070] In addition, the optical laminate according to one embodiment of the present invention has the following structure, wherein a primer layer, a base resin layer and a functional coating are sequentially stacked on a glass substrate of ultra-thin glass, so that the ratio of the total thickness of the primer layer, the base resin layer and the functional coating to the thickness of the glass substrate is controlled within a specific range, thereby ensuring excellent pencil hardness properties and bending resistance while preventing curling, thereby providing excellent workability. In particular, the optical laminate according to one embodiment of the present invention exhibits a pencil hardness of 2H or higher, so that no indentation mark is left when a pen is used. In addition, the optical laminate according to one embodiment of the present invention can ensure bending properties even at a curvature radius of 3 mm. In addition, the optical laminate according to one embodiment of the present invention shows anti-fouling properties, wear resistance and chemical resistance.

[0071] Figure 1 and Figure 2 Each of them is a cross-sectional view of the structure of an optical layered body according to an embodiment of the present invention.

[0072] refer to Figure 1 According to one embodiment of the present invention, an optical laminate 100 includes a glass substrate 110, a primer layer 120, a base resin layer 130 and a functional coating layer 140 stacked in sequence, and the primer layer 120 is formed on the glass substrate 110 to cover the upper surface and side surfaces of the glass substrate 110, and the base resin layer 130 is formed on the primer layer 120 to cover the upper surface and side surfaces of the primer layer 120.

[0073] refer to Figure 2 According to one embodiment of the present invention, an optical laminate 100 includes a glass substrate 110, a primer layer 120, a base resin layer 130 and a functional coating layer 140 stacked in sequence, and the primer layer 120 is formed to cover the entire surface of the glass substrate 110, and the base resin layer 130 is formed to cover the entire surface of the primer layer 120.

[0074] Hereinafter, each component of the optical stack will be described in detail.

[0075] The glass substrate 110 is ultra-thin glass (UTG) having a thickness of less than 100 μm. For example, the thickness of the glass substrate 110 is at least 10 μm and less than 100 μm, preferably 20 μm to 95 μm, and more preferably 30 μm to 90 μm.

[0076] If the thickness of the glass substrate 110 is greater than 100 μm, bending resistance may be reduced.

[0077] The ultra-thin glass may contain one or more selected from the group consisting of aluminoborosilicate, borosilicate, alkaline lead silicate, soda lime, lithium aluminosilicate and aluminosilicate, preferably one or more selected from the group consisting of soda lime, lithium aluminosilicate and aluminosilicate.

[0078] Ultra-thin glass can be cut unit by unit from the original sheet, wherein the cut surface (i.e., the side of the ultra-thin glass) can be uncurved and vertical, and can be polished to have a uniform side roughness. Due to polishing, the polished ultra-thin glass can have an edge at the junction of the top surface and the side surface. The edge can be tapered or curved.

[0079] The ultra-thin glass may be manufactured by the manufacturing method described below, but is not limited thereto.

[0080] The method of manufacturing ultra-thin glass may include the steps of: cutting an original sheet of glass into units; polishing cut surfaces of the units; etching the polished units; and repairing the polished cut surfaces of the units.

[0081] In addition, the method for manufacturing ultra-thin glass may further include the steps of cleaning, chemical strengthening and / or chemical polishing after the repairing step.

[0082] Steps for cutting raw sheet glass into units

[0083] First, a plurality of units are prepared by cutting an original sheet of glass into units.

[0084] The step of cutting the raw glass sheet into units is to shape the raw glass sheet into a shape that matches the design of the device to be used. This step can be performed to form multiple units. This step can be performed without laminating the raw glass sheet into multiple layers. This has the following advantages: unit traceability in the event of a defect, simplified manufacturing process by omitting the lamination step, reduced defect rates due to residues that may occur during the lamination step, and the ability to freely select the shape of the glass side surfaces.

[0085] The cutting step is not particularly limited as long as it can form a plurality of units by cutting the original sheet glass, and in one embodiment, the cutting step can form a plurality of units having a specific shape using a diamond cutting wheel or a CNC cutting machine equipped with a laser.

[0086] Steps for polishing the cut surface of the unit cell

[0087] Then, the method for manufacturing ultra-thin glass further includes a step of polishing the cut surface of the unit.

[0088] The polishing may preferably be physical polishing, most preferably physical polishing, so that the cut surface of the unit has a rounded shape. The cut surface of the unit refers to the side of the unit. In this case, the thickness of the cut unit can be the same as the thickness of the original sheet glass.

[0089] Physical polishing includes physically polishing the debris of the cut surface after the cutting step while processing the unit side into the desired shape. In this case, the thickness of the cut unit can be the same as the thickness of the original sheet glass before cutting.

[0090] The polished cut surface (ie, the side surface of the unit) may have a gently rounded shape having a predetermined curvature in terms of stability to reduce the possibility of breakage during post-processing.

[0091] The physical polishing step is not particularly limited as long as it can physically polish the debris generated during cutting. In one embodiment, it can be performed by a roughing step including grinding the cut surface of the cutting unit using a chamfering tool of 400 mesh or less; a grinding step including polishing the cut surface of the unit that has undergone the roughing step using a chamfering tool of about 500-800 mesh; and a finishing step including polishing the cut surface of the unit that has undergone the grinding step using a chamfering tool of 1200 mesh or more.

[0092] Steps for etching the polished unit and repairing the polished cut surface of the polished unit

[0093] The method may then include etching the polished unit and repairing the polished cut surface of the polished unit. This step may include simultaneously performing the steps of etching the polished unit and repairing the polished cut surface of the polished unit. In addition, the repaired cut surface refers to the side surface of the final ultra-thin glass unit.

[0094] In the repair step, the polished cell may be etched without any protective material (such as resin or film) to prevent impact on the glass during the process or to mask it against the etchant.

[0095] The polished cell can be made ultra-thin by a chemical etching process while repairing the polished cut surface of the cell to obtain cell-by-cell ultra-thin glass.

[0096] Specifically, the step of etching the polished cell includes but is not limited to chemical etching. The step of etching the polished cell allows the cell to be ultra-thin.

[0097] Ultra-thinning refers to the process of thinning glass to a thickness of less than 100 μm.

[0098] Although etching of the polished cell and repair of the polished cut surface of the polished cell may be performed separately, from the viewpoint of simplifying the process, it is preferred to perform repair of the cut surface of the polished cell by the same method simultaneously with etching of the polished cell.

[0099] When the etching and repair steps are performed simultaneously, they are performed to thin the thick-film element while processing the cut surface into a smooth, rounded shape. The repair step improves the edge strength of the cut element, and after repair, the cut surface can be processed into a shape that is smoother and rounder than the shape of the cut surface after polishing. Repairing removes defects such as chipping of the cut surface caused by physical polishing and reduces roughness, which can suppress fractures caused by bending. Preferably, the rounded surface has a gentle curve.

[0100] In the chemical etching step, an immersion method of immersing the unit in an etchant may be used. In one embodiment, this may be performed by including at least one of the following: a unit jig clamping step of clamping the unit in a jig for handling the unit; a jig dipping step of dipping the jig into an etchant tank filled with an etchant to allow the unit to be immersed in the etchant; a chemical etching step of uniformly chemically etching the thickness and cut surface of the immersed unit at a certain etching rate; a jig ejecting step of ejecting the jig from the etchant tank after completing the chemical etching; and a unit separating step of separating the chemically etched unit from the jig.

[0101] Etching can also be supplemented by implementing a side spray or top spray method alongside the immersion method, where the cell is completely immersed in the etchant. Alternatively, the side spray or top spray method can be performed independently of the immersion method, where the cell is completely immersed in the etchant. In this case, as the glass is cut cell by cell, the surface tension of the sprayed etchant allows the etchant to be adsorbed onto the surface of the glass cell, thereby achieving both etching and side repair.

[0102] In the above-mentioned etching and repairing steps, a plurality of glass units may be moved by the upper jig and the lower jig, respectively, and etching and repairing may be performed while minimizing contact between each glass unit.

[0103] In one or more embodiments, the etchant may include at least one selected from the group consisting of hydrofluoric acid (HF), ammonium fluoride (NH4F), ammonium bifluoride (NH4HF2), sodium fluoride (NaF), sodium bifluoride (NaHF2), lithium fluoride (LiF), potassium fluoride (KF), and calcium fluoride (CaF2).

[0104] If etching of the polishing unit and repairing of the polishing cut surface of the polishing unit are performed in separate steps, the chemical etching step as described above may be performed to etch the unit, and then the repairing step of the polishing cut surface of the polishing unit may be further performed by applying the same method as the chemical etching step described above.

[0105] Cleaning, chemical strengthening and / or chemical polishing steps

[0106] The method for manufacturing ultra-thin glass may further include cleaning, chemical strengthening and / or chemical polishing steps. The order of the cleaning step, chemical strengthening step and chemical polishing step may be changed, added or omitted as needed.

[0107] The cleaning step can be used to remove residual debris and etchant from the previous process. The cleaning process for removing residual debris and etchant can be any commonly used process. In one embodiment, the cleaning step can be performed using a cleaning solution. The cleaning step can use a spraying method of spraying the cleaning solution or an immersion method of immersing in the cleaning solution.

[0108] The cleaning solution is not particularly limited as long as it is used to clean the surface of the ultra-thin glass. In one or more embodiments, it can be pure water (DI water), or an alkaline cleaning solution containing potassium hydroxide (KOH) or sodium hydroxide (NaOH).

[0109] The chemical strengthening step aims to strengthen the ultrathin glass by immersing the ultrathin glass in a molten salt to exchange alkali ions in the ultrathin glass with alkali ions in the molten salt. In one embodiment, the chemical strengthening step can be performed by: a preheating step of slowly increasing the temperature of the ultrathin glass; chemically strengthening the preheated ultrathin glass by ion substitution; and annealing the strengthened ultrathin glass at room temperature.

[0110] The preheating step of slowly increasing the temperature of the ultra-thin glass is to prevent damage due to a sudden change in temperature in the ultra-thin glass during the chemical strengthening step performed at a high temperature of 350° C. to 500° C. This step may be performed to gradually increase the temperature before immersing the ultra-thin glass in the ion substitution solution.

[0111] The chemical strengthening step can be achieved by + Ion glass and K-containing + ions in contact with the salt, which results in the Na + and K + The exchange of ions proceeds in an inward direction, which allows K + Ions enter the Na + ions occupy the position, and since K + The ionic radius is larger than that of Na +The ionic radius of the glass creates a compressive force around the network, which strengthens the glass.

[0112] K + The depth of ion substitution by chemical strengthening is not particularly limited, but may be 5% to 40% of the cell thickness, preferably 10% to 35%, and more preferably 15% to 30% in terms of improved bending resistance.

[0113] In addition, the target depth of chemical strengthening may vary depending on the thickness of the glass. For example, the depth (thickness) of chemical strengthening may vary depending on the thickness of the glass, as shown in Table 1 below.

[0114] [Table 1]

[0115]

[0116] The ion substitution solution used for chemical strengthening may be any conventionally used ion substitution solution, and in one embodiment may include potassium nitrate (KNO 3 ).

[0117] After the chemical strengthening process, an annealing step and a process for removing impurities may be further performed. The process for annealing and removing impurities may be any conventionally used process, and in one embodiment may include a natural annealing process in contact with external air, followed by a cleaning process to remove impurities such as potassium nitrate.

[0118] In the chemical polishing step, a chemical polishing solution is used to polish the ultra-thin glass. In order to improve bending resistance, the thickness of the ultra-thin glass after chemical polishing is at least 80% but less than 100%, preferably at least 90% but less than 100%, of the thickness of the ultra-thin glass before chemical polishing.

[0119] The chemical polishing liquid may include at least one of hydrofluoric acid (HF) and ammonium fluoride (NH 4 F), but is not particularly limited as long as it is generally used in a process of polishing ultra-thin glass.

[0120] Furthermore, after the above-mentioned chemical polishing step, an additional cleaning step may be performed as needed.

[0121] The primer layer 120 is formed to cover the upper surface and side surfaces of the glass substrate 110. Alternatively, the primer layer 120 is formed to cover the entire surface of the glass substrate 110.

[0122] The primer layer 120 further improves adhesion between the glass substrate 110 and the base resin layer 130 .

[0123] In one embodiment of the present invention, the primer layer 120 may be formed of a composition for forming a primer layer including at least one of a polyurethane resin and a polyester resin, and may preferably be formed of a composition for forming a primer layer including a polyurethane resin.

[0124] In particular, in order to prevent yellowing and improve hardness and bending resistance even under high temperature or ultraviolet conditions, the primer layer can be formed of a composition for forming a primer layer including an aqueous polyurethane resin and a stabilizer, and the stabilizer can include a primary thermal stabilizer and a secondary thermal stabilizer.

[0125] Compared with solvent-based general-purpose polyurethane resins, water-based polyurethane resins have excellent optical properties and adhesion advantages.

[0126] Waterborne polyurethane resins include ionic resins and nonionic resins. Nonionic resins have good particle stability, but mechanical properties, such as film-forming ability and adhesive strength, are lower than those of waterborne polyurethane resins with ionic functional groups. Therefore, waterborne polyurethane resins with ionic functional groups are preferably used to maintain mechanical properties.

[0127] Waterborne polyurethane resins can be produced through a prepolymer manufacturing process using polyester polyols, diisocyanates, and chain extenders as raw materials. Specifically, waterborne polyurethane resins are synthesized by mixing polyester polyols and diisocyanates, reacting them at high temperatures to produce a prepolymer, then dispersing the prepolymer in water while stirring at high speeds, and then adding a chain extender and adjusting the molecular weight through polymerization of the dispersed prepolymer.

[0128] In addition, in the case of producing a water-dispersible polyurethane resin having an ionic functional group, a dispersant (ionizing agent) is further added to a polyester polyol and a diisocyanate, the reaction is carried out at a high temperature to produce a hydrophilic prepolymer, a neutralizing agent is added to neutralize the hydrophilic prepolymer, the neutralized hydrophilic prepolymer is added to water and stirred at a high speed to disperse it, a chain extender is added, and the molecular weight is adjusted by a polymerization reaction of the dispersed hydrophilic prepolymer to synthesize a water-dispersible polyurethane resin.

[0129] By specifically using polycaprolactone polyol (a type of polyester polyol) to compensate for its disadvantage of being hydrolyzed by water, waterborne polyurethane resins have the advantage of not being decomposed and maintaining adhesion even under high temperatures and high humidity. Furthermore, by using isophorone diisocyanate (an aliphatic diisocyanate), it can exhibit transparency compared to aromatic diisocyanates.

[0130] The waterborne polyurethane resin does not contain fluorine atoms, so it can maintain appropriate surface energy and provide adhesion to the film, and it does not contain a sulfonic group, so it can suppress haze generation, thereby exhibiting better optical characteristics.

[0131] The aqueous polyurethane resin may have a number average molecular weight of 10,000 to 4 million, preferably 20,000 to 2 million. When the number average molecular weight is within the above range, stability can be ensured in a water-dispersed state, coating properties are excellent, and mechanical properties are also good.

[0132] The content of the aqueous polyurethane resin may be 1% to 40% by weight based on 100% by weight of the total composition for forming the primer layer, but is not limited thereto. When the aqueous polyurethane resin is included within the above content range, excellent adhesion between the glass substrate and the base resin layer can be ensured, and coating properties can also be ensured.

[0133] Stabilizers include primary thermal stabilizers and secondary thermal stabilizers.

[0134] By including a combination of a primary heat stabilizer and a secondary heat stabilizer as a stabilizer, yellowing can be prevented even under high temperature or ultraviolet conditions by removing free radicals generated by heat or ultraviolet rays (free radical scavenging) and inhibiting further decomposition reactions.

[0135] Specifically, by including a combination of a primary heat stabilizer and a secondary heat stabilizer as a stabilizer, yellowing does not occur even after a high-temperature heat treatment at 100-250° C. for 20-60 minutes, thereby maintaining transparency.

[0136] Therefore, the primer layer 120 does not change even after being subjected to a high-temperature heat treatment when forming the base resin layer 130 described below, and can maintain its transparency.

[0137] For example, after the laminate in which the primer layer 120 is formed on the glass substrate 110 is heat-treated at a temperature of 100-250° C. for 20-60 minutes, the yellowness index YI of the laminate may be less than 1.0 according to ASTM E313-73.

[0138] When the polymer material reacts with oxygen due to heat or ultraviolet rays to cause decomposition, the primary heat stabilizer releases its own hydrogen, thereby stabilizing the free radicals by preventing the chain reaction of free radicals. Therefore, the primary heat stabilizer can prevent yellowing by the free radical scavenging effect.

[0139] The primary heat stabilizer may be at least one selected from phenolic heat stabilizers and amine heat stabilizers.

[0140] For example, the phenolic heat stabilizer may include 3,9-bis[2-3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethoxy]-2,4,8,10-tetraoxaspiro[5.5]undecane, pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3'5-di-tert-butyl-4-hydroxybenzyl)benzene, triethylene glycol, -bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 4,4'-thiobis(6-tert-butyl-3-methylphenol), tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-isocyanurate, 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2-thio- Diethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], N,N'-hexamethylene bis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamic acid), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,4-bis[(octylthio)methyl]-O-cresol, 1,6-hexanediol-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], Octaalkyl 3-(3,5-di-tert-butyl-4-hydroxyphenol) propionate, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-butylene-bis(3-methyl-6-tert-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-tris(4-hydroxybenzyl)benzene, and tetrakis[methylene-3-(3,5'-di-tert-butyl-4'-hydroxyphenylpropionate)]methane.

[0141] Commercially available products of the phenolic heat stabilizer include Irganox 1010 (manufactured by BASF), Sumilizer BBM-S (manufactured by Sumitomo Chemical), ADK STABAO-80 (manufactured by ADEKA), Sumilizer GP (manufactured by Sumitomo Chemical), and Irganox 1035 (manufactured by BASF).

[0142] For example, the amine heat stabilizer may include naphthylamine heat stabilizers, such as 1-naphthylamine, phenyl-1-naphthylamine, p-octylphenyl-1-naphthylamine, p-nonylphenyl-1-naphthylamine, p-dodecylphenyl-1-naphthylamine and phenyl-2-naphthylamine; phenylenediamine heat stabilizers, such as N,N'-diisopropyl-p-phenylenediamine, N,N'-diisobutyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-β-naphthyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine, dioctyl-p-phenylenediamine, phenylhexyl-p-phenylenediamine and phenyloctyl-p-phenylenediamine. Amines; diphenylamine heat stabilizers, such as dipyridylamine, diphenylamine, p,p'-di-n-butyldiphenylamine, p,p'-di-tert-butyldiphenylamine, p,p'-di-tert-amyldiphenylamine, p,p'-dioctyldiphenylamine, p,p'-dinonyldiphenylamine, p,p'-didecyldiphenylamine, p,p'-docosyldiphenylamine, p,p'-distyryldiphenylamine, p,p'-dimethoxydiphenylamine, 4,4'-bis(4-α,α-dimethylbenzoyl)diphenylamine, p-isopropoxydiphenylamine and dipyridylamine; phenothiazine heat stabilizers, such as phenothiazine, N-methylphenothiazine, N-ethylphenothiazine, 3,7-dioctylphenothiazine, phenothiazine carboxylates and phenothiazine.

[0143] The secondary heat stabilizer can inhibit the generation of peroxide radicals by reducing peroxides generated by free radicals during the above-mentioned decomposition reaction, thereby acting synergistically with the primary heat stabilizer to provide high-temperature heat resistance and prevent yellowing by preventing coloration.

[0144] The secondary heat stabilizer may be one or more selected from phosphorus-based heat stabilizers and sulfur-based heat stabilizers.

[0145] For example, the phosphorus-based thermal stabilizer may include 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, 2,2'-methylenebis(4,6-di-tert-butyl-1-phenoxy)(2-ethylhexyloxy)phosphine, 6-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]di Phosphoheptane, triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, 4,4'-butylene-bis(3-methyl-6-tert-butylphenyl ditridecyl) phosphite, octadecyl phosphite, tris(nonylphenyl) phosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(3,5-di-tert-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10 -phosphaphenanthrene-10-oxide, tris(2,4-di-tert-butylphenyl) phosphite, cycloneopentanetetralbis(2,4-di-tert-butylphenyl) phosphite, cycloneopentanetralbis(2,6-di-tert-butylphenyl) phosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4'-diylbisphosphonite and bis[2,4-bis(1,1-dimethylethyl)-6-methylphenyl]ethylphosphonate.

[0146] Commercially available products of phosphorus-based heat stabilizers include ADK STAB 1178, ADK STAB TPP, ADK STAB 1500, ADK STAB 135A, ADK STAB 517 available from Adeka Corporation; Sumilizer GP available from Sumitomo Chemical; and Irganox 1035 available from BASF.

[0147] For example, sulfur-based heat stabilizers may include 2,2-bis({[3-(dodecylthio)propionyl]oxy}methyl)-1,3-propanediyl-bis[3-(dodecylthio)propionate], 2-mercaptobenzimidazole, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearoyl-3,3'-thiodipropionate, pentaerythritol-tetrakis(3-laurylthiopropionate), 2-mercaptobenzimidazole, and the like.

[0148] The stabilizer may be present in an amount of 0.1 to 10% by weight based on 100% by weight of the total composition for forming the primer layer, but is not limited thereto. Inclusion of the stabilizer within the above range has the advantages of preventing the surface of the cured coating film from being decomposed by heat or ultraviolet radiation, not degrading optical properties, and not affecting curability during thermal curing.

[0149] The composition for forming the primer layer may further include a leveling agent.

[0150] The leveling agent is added to impart smoothness and coatability to the film when coated with the composition, and the composition may include one or more of a silicone-based leveling agent, a fluorine-based leveling agent, and an acrylic-based leveling agent.

[0151] Specifically, from BYK BYK-306, BYK-307, BYK-323, BYK-331, BYK-333, BYK-337, BYK-373, BYK-375, BYK-377, BYK-378, BYK-3530, BYK-3560, BYK-358N and BYK-361N from Chemistry, TEGO Glide from Degussa 410, TEGO Glide 411, TEGO Glide 415, TEGO Glide 420, TEGOGlide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide 455, TEGO Rad2100, TEGO Rad 2200N, TEGO Rad 2250, TEGO Rad 2300 and TEGO Rad 2500, FC-4430 and FC-4432 from 3M, etc. can be used as leveling agents, but are not limited thereto.

[0152] The leveling agent may be present in an amount of 0.01 to 1% by weight based on 100% by weight of the total composition for forming the primer layer, but is not limited thereto. Inclusion of the leveling agent within the above range is beneficial for maximizing the smoothness and coatability of the coating film while maintaining good hardness and flexibility.

[0153] The composition for forming the primer layer according to the present invention may further include a solvent.

[0154] The solvent may be used without limitation as long as it can dissolve or disperse the above components.

[0155] Examples of the solvent include alcohols (methanol, ethanol, isopropanol, butanol, methyl cellosolve, ethyl cellosolve, etc.), ketones (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, cyclohexanone, etc.), acetates (ethyl acetate, propyl acetate, n-butyl acetate, tert-butyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, methoxybutyl acetate, methoxypentyl acetate, etc.), hexanes (hexane, heptane, octane, etc.), benzenes (benzene, toluene, xylene, etc.), and ethers (diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, etc.). Each of the above exemplary solvents can be used alone or in combination of two or more.

[0156] The content of the solvent can be calculated as a remainder to constitute 100 weight percent of the composition for forming the primer layer. For example, based on 100 weight percent of the composition for forming the primer layer, the amount of the solvent can be 50-98 weight percent. If the amount of the solvent is less than this amount, the coating thickness cannot be reduced due to high viscosity, which not only reduces workability but also leads to poor flexibility. On the contrary, if the solvent content exceeds the above range, the desired coating thickness cannot be formed, and the coating solution may flow out during the drying process, contaminating the opposite side of the glass or film and causing stains.

[0157] The primer layer 120 may be formed by applying and curing the composition for forming the above-mentioned primer layer onto the glass substrate 110 .

[0158] The application can be by any known method, such as slot coating, knife coating, spin coating, casting, micro gravure coating, gravure coating, rod coating, roller coating, wire bar coating, dip coating, spray coating, screen printing, gravure printing, flexographic printing, offset printing, inkjet coating, dispenser printing, nozzle coating, capillary coating, etc.

[0159] For example, the primer layer forming composition can be applied to the side surfaces of the glass substrate 110 by standing the glass substrate 110 upright and immersing all four sides of the glass substrate 110 into the primer layer forming composition by 3 mm or less (e.g., about 1 mm). The primer layer forming composition can be applied to the top and / or bottom surfaces of the glass substrate 110 by slit coating the primer layer forming composition on the top and / or bottom surfaces of the glass substrate 110.

[0160] Curing can be performed by pre-baking and / or post-baking heat curing process.The heat curing process can be performed by any known method, preferably in an oven at 80-150°C for 1-5 minutes.

[0161] The primer layer can be formed by further adding a photocurable oligomer and / or monomer and a photoinitiator to form a photocuring process. In the case of photocuring, the primer layer is preferably formed by drying at a temperature of 300-1000 mJ / cm 2 The primer layer is formed by irradiating the primer layer with a cumulative UV light dose.

[0162] The thickness of the primer layer can be at least 0.1 μm and less than 10 μm, preferably 0.1-2 μm. If the thickness of the primer layer is within the above range, it is beneficial to adhere to the glass substrate. If the thickness of the primer layer is less than 0.1 μm, when the base resin layer is applied on top of the primer layer, it may be difficult to exhibit adhesion by penetrating the primer layer, and if the thickness of the primer layer is 10 μm or more, the optical performance may be reduced. When the primer layer is formed to cover the entire surface of the glass substrate, the thickness of the primer layer is the sum of the thicknesses of the primer layers present on the top and bottom surfaces of the glass substrate.

[0163] The base resin layer 130 is formed to cover the top surface and the side surfaces of the primer layer 120. Alternatively, the base resin layer 130 is formed to cover the entire surface of the primer layer 120.

[0164] The base resin layer 130 supports a functional coating layer 140 described later, and serves as a protective layer to prevent breakage of the glass substrate 110. In addition, the base resin layer 130 plays a role in controlling bending resistance, pencil hardness, and curling characteristics of the optical laminate.

[0165] In one embodiment of the present invention, the base resin layer may be formed from a composition for forming a base resin layer, the composition including at least one of a polyimide resin and a polyamide-imide resin. This is because the base resin layer has excellent durability against repeated bending, making it easier to apply to flexible displays while ensuring pencil hardness and curling characteristics. In particular, in terms of bending resistance, pencil hardness, and curling characteristics, the base resin layer may be formed from a composition for a base resin layer including a polyamide-imide resin.

[0166] In particular, the base resin layer has a controlled elastic modulus of 3.3 to 5.2 GPa.

[0167] By controlling the elastic modulus of the base resin layer to be 3.3 to 5.2 GPa, preferably 3.8 to 5.2 GPa, and even more preferably 4.6 to 5.2 GPa, the bending resistance, pencil hardness, and curling characteristics of the optical laminate can be simultaneously ensured.

[0168] If the elastic modulus of the base resin layer exceeds 5.2 GPa, shrinkage caused by drying of the base resin layer increases shrinkage stress, which is proportional to the product of the elastic modulus and curl (strain). Even after the display module is bonded, this shrinkage stress can affect the entire module, leading to a significant tendency toward curling of the functional coating. If it is less than 3.3 GPa, the elastic modulus of the base resin layer itself is insufficient, reducing its ability to resist deformation and recovery from external forces. As a result, the pencil hardness of the base resin layer itself can be reduced, which can ultimately reduce the pencil hardness of the entire optical laminate.

[0169] The elastic modulus is a value that indicates the stiffness of a material, also known as the modulus of elasticity. The elastic modulus is defined as the ratio of stress to strain in the elastic region and can be determined from the slope of the linear elastic region of a stress-strain curve obtained by tensile testing a sample of the material.

[0170] Specifically, the elastic modulus of base resin layer can be measured under the stretching assessment mode using a universal testing machine (UTM). Base resin layer can be deposited on the glass that does not form a primer layer, and peels off to only obtain the base resin layer after drying. Gained resin layer can use the super cutting machine of JIS-K7139 rod type specification to make tensile test sample, and measures with the extension speed of 4mm / min under the stretching assessment mode of universal testing machine.

[0171] The elastic modulus of the base resin layer can be adjusted by controlling the type and molar ratio of the repeating units constituting the resin, the weight average molecular weight of the resin, and the like.

[0172] Polyimide resin refers to a resin containing repeating units of imide groups.

[0173] The polyimide resin can be prepared by imidizing a polyamic acid obtained by polycondensation of a tetracarboxylic acid compound and a diamine compound. The imidization can be performed chemically and / or thermally.

[0174] Tetracarboxylic acid compounds represent tetracarboxylic acids or tetracarboxylic acid derivatives. Tetracarboxylic acid derivatives are, for example, anhydrides of tetracarboxylic acids, preferably dianhydrides, acid chlorides, etc. Tetracarboxylic acid compounds include, for example, aromatic tetracarboxylic acids, such as aromatic tetracarboxylic acids and their anhydrides, preferably their dianhydrides; aliphatic tetracarboxylic acid compounds, such as aliphatic tetracarboxylic acids and their anhydrides, preferably their dianhydrides; etc. These tetracarboxylic acid compounds can be used alone or in combination of two or more.

[0175] Specific examples of the aromatic tetracarboxylic dianhydride include 4,4′-oxydiphthalic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 2,2′,3,3′-benzophenonetetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 2,2′,3,3′-biphenyltetracarboxylic dianhydride, 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 4,4′-(hexafluoroisopropyl)propane 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, 4,4′-(p-phenylenedioxy)diphthalic dianhydride, 4,4′-(isophenylenedioxy)diphthalic dianhydride, 1,2,4,5-pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, etc.

[0176] Examples of the aliphatic tetracarboxylic dianhydride may include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3′,4,4′-tetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentanetetracarboxylic dianhydride, and the like.

[0177] Aliphatic diamines and / or aromatic diamines can be used as the diamine compound.

[0178] Examples of the aliphatic diamine may include hexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, norbornanediamine, 4,4′-diaminodicyclohexylmethane, and the like.

[0179] Examples of the aromatic diamines may include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-diphenylenediamine, p-diphenylenediamine, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylether, 3,4'-diaminodiphenylether, 3,3'-diaminodiphenylether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, bis( 4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 2,2-bis(4-(3-aminophenoxy)phenyl)propane, 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-amino-3-methylphenyl)fluorene, 9,9-bis(4-amino-3-chlorophenyl)fluorene, 9,9-bis(4-amino-3-fluorophenyl)fluorene, etc.

[0180] The molar ratio of the tetracarboxylic acid compound and the diamine compound may be adjusted to control the elastic modulus of the base resin layer to the above range.

[0181] The weight average molecular weight (Mw) of the polyimide resin may be 100,000 to 1 million in standard polystyrene equivalent. When the weight average molecular weight (Mw) of the polyimide resin is within the above range, coating properties may be ensured when forming a coating film, and the optical laminate may have desired bending resistance, pencil hardness, and curling properties.

[0182] The polyamideimide resin refers to a resin containing a repeating unit including an imide group and a repeating unit including an amide group.

[0183] The polyamide-imide resin can be prepared by imidizing polyamic acid obtained by polycondensation of a tetracarboxylic acid compound, a dicarboxylic acid compound, and a diamine compound. Imidation can be performed chemically and / or thermally.

[0184] The tetracarboxylic acid compound and the diamine compound may be the same as those used in the preparation of the polyimide resin.

[0185] The dicarboxylic acid compound refers to a dicarboxylic acid or a dicarboxylic acid derivative, and the dicarboxylic acid derivative is, for example, acid chlorides or esters of those dicarboxylic acids. The dicarboxylic acid compound may be used alone or in combination of two or more.

[0186] Exemplary dicarboxylic acid compounds include, for example, 2,5-thiophenedicarboxylic acid, 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4,4′-oxybisbenzoic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, 3,3′-biphenyldicarboxylic acid, terephthaloyl chloride (TPC), 4,4′-biphenyldicarboxylic acid chloride (BPDC), 4,4′-oxybis(benzoyl chloride) (OBBC), and the like.

[0187] The molar ratio of the tetracarboxylic acid compound, the dicarboxylic acid compound, and the diamine compound may be adjusted to control the elastic modulus of the base resin layer to fall within the above range.

[0188] The weight average molecular weight (Mw) of the polyamide-imide resin may be 100,000 to 1 million in standard polystyrene equivalent. When the weight average molecular weight (Mw) of the polyamide-imide resin is within the above range, coating properties can be ensured when forming a coating film, and the optical laminate can have desired bending resistance, pencil hardness, and curling properties.

[0189] The composition for forming the base resin layer may further contain additives such as an ultraviolet absorber, inorganic particles, a surfactant, an adhesion enhancer, and the like, as needed.

[0190] The composition for forming the base resin layer of the present invention may further contain a solvent.

[0191] The solvent may be used without limitation as long as it can dissolve or disperse the above components.

[0192] Exemplary solvents may include alcohol solvents (methanol, ethanol, isopropanol, butanol, methyl cellosolve, ethyl cellosolve, etc.), organic solvents containing nitrogen atoms (N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolidinone, etc.), dimethyl sulfoxide, γ-butyrolactone, etc. Each of the above exemplary solvents may be used alone or in combination of two or more.

[0193] The solvent may be contained in a balance to constitute 100 wt % of the composition for forming the base resin layer. For example, the solvent may be used in an amount that allows the viscosity of the composition to be adjusted to a desired range to ensure coating properties.

[0194] The base resin layer 130 may be formed by applying the above-described composition for forming a base resin layer on the primer layer 120 and curing it.

[0195] The application can be by any known method, such as slot coating, knife coating, spin coating, casting, micro gravure coating, gravure coating, rod coating, roller coating, wire bar coating, dip coating, spray coating, screen printing, gravure printing, flexographic printing, offset printing, inkjet coating, dispenser printing, nozzle coating, capillary coating, etc.

[0196] The application of the composition for forming a base resin layer on the side and top surfaces of the primer layer 120 can be performed by applying the composition for forming a base resin layer to cover the top surface of the primer layer 120. Since the primer layer 120 has excellent adhesion, if the application area is adjusted to be wide so as to cover the top surface of the primer layer 120, the application can be performed simultaneously on the side and top surfaces. In order to apply to all surfaces of the primer layer 120 including the side, top, and bottom surfaces, the application is performed as described above for the side and top surfaces, and then the application is performed on the bottom surface.

[0197] Curing can be carried out by a pre-bake and / or post-bake heat curing process.The heat curing process can be carried out by any known method, preferably using an oven.

[0198] Prebaking is preferably performed at 140° C. or lower if the base resin is a polyimide resin, and postbaking is preferably performed at 200° C. or higher if the base resin is a polyamideimide resin, and at 150° C. or higher if the base resin is a polyamideimide resin.

[0199] In terms of pencil hardness of the optical laminate, the base resin layer can have a thickness of 3-50 μm, preferably 5-30 μm, and more preferably 5-10 μm. If the base resin layer is thinner than this range, the glass may be damaged during handling due to a lack of protection. If the thickness is thicker than this range, curling caused by drying of the base resin layer may be a problem. When the base resin layer is formed to cover the entire surface of the primer layer, the thickness of the base resin layer is the sum of the thicknesses of the base resin layer on the top and bottom surfaces of the glass substrate.

[0200] The functional coating layer 140 is formed on the base resin layer 130 .

[0201] The functional coating 140 improves surface hardness. Furthermore, the functional coating 140 exhibits antifouling properties, excellent wear resistance, and an excellent elastic recovery rate, which can provide excellent pen depression suppression properties, as well as excellent durability effects such as scratch resistance, chemical resistance, and bending resistance. Furthermore, the functional coating 140 controls the bending resistance and curling characteristics of the optical laminate.

[0202] The functional coating 140 may be a hard coating.

[0203] In one embodiment of the present invention, the hard coating layer may be formed of a hard coating composition including a light-transmitting resin, a compound containing a fluorine-based UV-curable functional group, a photoinitiator, and a solvent.

[0204] The light-transmitting resin is a light-curable resin, which may include but is not limited to light-curable (meth)acrylate oligomers and / or monomers.

[0205] As the photocurable (meth)acrylate oligomer, epoxy (meth)acrylate, urethane (meth)acrylate, polyhedral oligomeric silsesquioxane (meth)acrylate, dendritic (meth)acrylate, etc. can be used, preferably one or more of urethane (meth)acrylate and dendritic (meth)acrylate.

[0206] Urethane (meth)acrylate can be prepared by reacting a (meth)acrylate having an intramolecular hydroxyl group with a compound having an isocyanate group in the presence of a catalyst. Specific examples of (meth)acrylates having an intramolecular hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxyisopropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, caprolactone-modified hydroxy acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and the like. In addition, specific examples of the compound having an isocyanate group include 1,4-diisocyanate butane, 1,6-diisocyanate hexane, 1,8-diisocyanate octane, 1,12-diisocyanate dodecane, 1,5-diisocyanate-2-methylpentane, trimethyl-1,6-diisocyanate hexane, 1,3-bis(isocyanatomethyl)cyclohexane, trans-1,4-cyclohexene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), isophorone Ketone diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, xylene-1,4-diisocyanate, tetramethylxylene-1,3-diisocyanate, 1-chloromethyl-2,4-diisocyanate, 4,4'-methylenebis(2,6-dimethylphenylisocyanate), 4,4'-oxybis(phenylisocyanate), trifunctional isocyanates derived from hexamethylene diisocyanate, trimethylolpropane-adduct toluene diisocyanate, and the like.

[0207] Dendritic (meth)acrylate refers to a (meth)acrylate oligomer having a dendritic structure, wherein "dendritic structure" refers to a shape in which monomers radially branch, polymerize, and diffuse radially from a single core, and the dendritic (meth)acrylate can be used without limitation as long as it corresponds to the above shape.

[0208] Commercially available dendritic (meth)acrylates include Miramer SP1106 from Miwon Co., Ltd., Viscoat 1000, Viscoat 1020, and Viscoat 1080 from Osaka Yugi Co., Ltd.

[0209] Monomers can be used in a conventional manner without limitation. In particular, monomers having unsaturated groups such as (meth) acryloyl, vinyl, styryl, allyl, etc. as photocurable functional groups in the molecule are preferred. Among them, monomers having (meth) acryloyl are preferred.

[0210] Specific examples of the monomer having a (meth)acryloyl group may be one or more selected from the group consisting of neopentyl glycol acrylate, 1,6-hexanediol di(meth)acrylate, propylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, 1,2,4-cyclohexane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, stearyl (meth)acrylate, tetrahydrofuranyl (meth)acrylate, phenylethoxy (meth)acrylate and isobornyl (meth)acrylate.

[0211] Each of the photocurable (meth)acrylate oligomers and monomers exemplified above may be used alone or in combination of two or more.

[0212] The light-transmitting resin may be present in an amount of 1 to 80% by weight based on 100% by weight of the total hard coating composition. If the light-transmitting resin content is less than 1% by weight, sufficient hardness improvement may be difficult to achieve, and if it exceeds 80% by weight, severe curling may occur.

[0213] The compound containing a fluorine-based UV curable functional group is a component that imparts antifouling, abrasion resistance, and chemical resistance. The compound containing a fluorine-based UV curable functional group is not particularly limited as long as it contains both fluorine and a UV curable functional group and can chemically bond with the light-transmitting resin that forms the hard coat matrix.

[0214] As the compound containing a fluorine-based UV-curable functional group, one or more selected from the group consisting of (meth)acrylates containing perfluoroalkyl groups, (meth)acrylates containing perfluoropolyether groups, (meth)acrylates containing perfluorocycloaliphatic groups, and (meth)acrylates containing perfluoroaryl groups can be used. In this case, this is advantageous because it has excellent antifouling properties and, by forming a chemical bond with the hard coat layer, has excellent durability, maintaining antifouling properties for a long time even after repeated use.

[0215] The fluorine-based UV-curable functional group-containing compound preferably has 1 to 6 UV-curable functional groups.

[0216] Compounds containing fluorine-based UV curable functional groups include, for example, 2,2,2-trifluoroethyl acrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2-perfluorobutylethyl acrylate, 3-perfluorobutyl-2-hydroxypropyl acrylate, 2-perfluorohexylethyl acrylate, 3-perfluorohexyl-2-hydroxypropyl acrylate, 2-perfluorooctylethyl acrylate, 3-perfluorooctyl-2-hydroxypropyl acrylate, 2-perfluorodecylethyl acrylate, 2-perfluoro-3-methyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctyl-2-hydroxypropyl acrylate, 2-perfluorodecylethyl acrylate, 2-perfluoro-3-methyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorodec ... butyl ethyl acrylate, 3-perfluoro-3-methoxybutyl-2-hydroxypropyl acrylate, 2-perfluoro-5-methylhexylethyl acrylate, 3-perfluoro-5-methylhexyl-2-hydroxypropyl acrylate, 2-perfluoro-7-methyloctyl-2-hydroxypropyl acrylate, tetrafluoropropyl acrylate, octafluoropentyl acrylate, dodecafluoroheptyl acrylate, hexafluorononyl acrylate, hexafluorobutyl acrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,3 ,3,3-pentafluoropropyl methacrylate, 2-perfluorobutylethyl methacrylate, 3-perfluorobutyl-2-hydroxypropyl methacrylate, 2-perfluorooctylethyl methacrylate, 3-perfluorooctyl-2-hydroxypropyl methacrylate, 2-perfluorodecylethyl methacrylate, 2-perfluoro-3-methylbutylethyl methacrylate, 3-perfluoro-3-methylbutyl-2-hydroxypropyl methacrylate, 2-perfluoro-5-methylhexylethyl methacrylate, 3 -Perfluoro-5-methylhexyl-2-hydroxypropyl methacrylate, 2-perfluoro-7-methyloctylethyl methacrylate, 3-perfluoro-6-methyloctyl methacrylate, tetrafluoropropyl methacrylate, octafluoropentyl methacrylate, octafluoropentyl methacrylate, dodecafluoroheptyl methacrylate, hexafluorononyl methacrylate, 1-trifluoromethyltrifluoroethyl methacrylate, hexafluorobutyl methacrylate, triacryloyl-heptadecafluorononyl-pentaerythritol, etc.

[0217] Commercially available examples of such fluorine-containing UV-curable functional group compounds include KY-1203 (Shin-Etsu Silicones), OPTOOL DAC-HP (Daikin), UVAS-2003 (Suyang Chemtech), and the like.

[0218] The content of the compound containing a fluorine-based UV-curable functional group can be greater than 0.01% by weight and less than 10% by weight, based on 100% by weight of the total amount of the hard coating composition. It is preferable that the compound containing a fluorine-based UV-curable functional group be included in the above range because it can impart excellent wear resistance and antifouling effects. If the content of the compound containing a fluorine-based UV-curable functional group is less than the above range, it may be difficult to achieve sufficient wear resistance or antifouling properties, and if the content exceeds the above range, hardness and / or scratch resistance may be reduced.

[0219] In one embodiment of the present invention, a photoinitiator is included to induce photocuring of the hard coating composition. The photoinitiator may include, for example, a photo radical initiator capable of forming free radicals upon exposure to light.

[0220] Examples of such photoinitiators include type 1 initiators that decompose molecules to generate radicals due to differences in chemical structure or molecular binding energy, and type 2 initiators that coexist with tertiary amines to induce deprotonation of hydrogen.

[0221] For example, type 1 initiators may include acetophenones such as 4-phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone, 4-tert-butyltrichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropane-1-one, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone, and 1-hydroxycyclohexylphenylketone; benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzyl dimethyl ketal; phosphine oxides; titanocene compounds; and the like.

[0222] For example, type 2 initiators may include benzophenones such as benzophenone, benzoylbenzoic acid, benzoylbenzoic acid methyl ether, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzo-4'-methyldiphenyl sulfide, and 3,3'-methyl-4-methoxybenzophenone; thioxanthones such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, and the like.

[0223] The above-mentioned photoinitiators can be used alone or in combination of two or more. In addition, the above-mentioned type 1 initiator and type 2 initiator can be used alone or in combination.

[0224] The photoinitiator content may be approximately 0.1-10% by weight, preferably approximately 1-5% by weight, based on 100% by weight of the total hard coating composition. If the photoinitiator content is less than 0.1% by weight, sufficient curing may not be achieved, and the mechanical properties and adhesion of the hard coating film or hard coating may not be maintained. If the photoinitiator content exceeds 10% by weight, poor adhesion, cracking, and curling may occur due to shrinkage during curing.

[0225] The solvent can be used without limitation as long as it is known in the art and can dissolve or disperse the above composition. In addition, the solvent is used to provide time for the compound containing a fluorine-based UV curable functional group to float to the outermost surface of the coating layer due to the difference in surface tension during the process of applying the hard coating composition to the substrate and drying it.

[0226] Examples of the solvent include alcohols (methanol, ethanol, isopropanol, butanol, methyl cellosolve, ethyl cellosolve, etc.), ketones (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, cyclohexanone, etc.), acetates (ethyl acetate, propyl acetate, n-butyl acetate, tert-butyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, methoxybutyl acetate, methoxypentyl acetate, etc.), hexanes (hexane, heptane, octane, etc.), benzenes (benzene, toluene, xylene, etc.), and ethers (diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, etc.). Each of the above exemplary solvents can be used alone or in combination of two or more.

[0227] Preferably, a good solvent alone or a mixed solvent containing a good solvent and a poor solvent is used as the solvent. The good solvent and the poor solvent may be appropriately selected according to the material of the transparent film used as the base film.

[0228] The solvent content can be 10-95% by weight, based on 100% by weight of the total hardcoat composition. If the solvent content is less than this, the viscosity increases, which not only reduces workability but also prevents sufficient substrate swelling. Conversely, if the solvent content exceeds this range, the drying process takes a significant amount of time and is uneconomical. Furthermore, due to excessive swelling of the base film, haze may occur. Therefore, it should be used appropriately within this range.

[0229] The hard coating composition may further comprise inorganic particles.

[0230] The inorganic particles may be inorganic nanoparticles, which are added to improve the elastic recovery of the hard coating layer.

[0231] In particular, the inclusion of inorganic nanoparticles in the hard coating composition can have the advantage of further improving mechanical properties. More specifically, the inorganic nanoparticles are uniformly distributed in the coating film, which has the advantage of improving mechanical properties such as pen pressure and pencil hardness.

[0232] The inorganic nanoparticles may have an average particle size of 1-100 nm, particularly 1-80 nm, and more particularly 5-50 nm. When the average particle size of the inorganic nanoparticles falls within the above range, agglomeration in the composition can be prevented, thereby enabling the formation of a uniform coating film. Furthermore, degradation of the optical and mechanical properties of the coating film can be prevented.

[0233] The inorganic nanoparticles may include one or more selected from the group consisting of Al2O3, SiO2, ZnO, ZrO2, BaTiO3, TiO2, Ta2O5, Ti3O5, ITO, IZO, ATO, ZnO-Al, Nb2O3, SnO and MgO, but are not limited thereto, and may include metal oxides commonly used in the art.

[0234] Specifically, the inorganic nanoparticles may be Al2O3, SiO2 and / or ZrO2. The inorganic nanoparticles may be commercially manufactured or purchased. In the case of commercially available products, the inorganic nanoparticles may be dispersed in an organic solvent at a concentration of 10-80 wt%.

[0235] The hard coating composition may further comprise a leveling agent to impart smoothness and coating properties to the film when coated with the composition.

[0236] The leveling agent can be selected from commercially available silicone leveling agents, fluorine leveling agents and acrylic polymer leveling agents. For example, BYK-323, BYK-331, BYK-333, BYK-337, BYK-373, BYK-375, BYK-377 and BYK-378 from BYK Chemistry, TEGO Glide 410, TEGO Glide 411, TEGO Glide 415, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide 455, TEGO Rad 2100, TEGO Rad 2200N, TEGO Rad 2250, TEGO Rad 2300 and TEGORad 2500 from Degussa, FC-4430 and FC-4432 from 3M, etc. can be used as leveling agents. The leveling agent may be included in an amount of 0.1 to 1 wt % based on 100 wt % of the total hard coating composition.

[0237] In addition to the above components, the hard coating composition may further include components commonly used in the art, such as UV stabilizers, heat stabilizers, antioxidants, lubricants, antifouling agents, and the like.

[0238] UV stabilizers are additives added to protect the coating film from UV light by blocking or absorbing UV radiation, because the surface of the cured coating film is degraded by continuous exposure to UV radiation, resulting in discoloration and brittleness. UV stabilizers are divided into absorbers, quenchers and hindered amine light stabilizers (HALS) according to their mechanism of action. In addition, according to their chemical structure, they can be divided into phenyl salicylate (absorber), benzophenone (absorber), benzotriazole (absorber), nickel derivatives (quencher) and free radical scavengers. There is no particular limitation on UV stabilizers, as long as they do not significantly change the initial color of the coating.

[0239] Thermal stabilizers are commercially available, and primary thermal stabilizers of the polyphenol type and secondary thermal stabilizers of the phosphite type and lactone type may be used alone or in combination.

[0240] The above-mentioned UV stabilizers and heat stabilizers can be used in appropriate amounts without affecting the UV curability.

[0241] The hard coating layer may be prepared by applying a hard coating composition to one side of the base resin layer, drying it, and then UV curing it.

[0242] The hard coating composition may be applied to the base resin layer using any suitable method known in the art, such as die coater, air knife, reverse roll, spray, doctor blade, casting, gravure printing, micro gravure printing, spin coating, and the like.

[0243] After the hard coating composition is applied on the base resin layer, it is dried by evaporating volatiles at a temperature of 30-150° C. for 10 seconds to 1 hour, more specifically 30 seconds to 30 minutes, and then cured by irradiation with UV light. The irradiation amount of UV light can be specifically about 0.01-10 J / cm 2 , more specifically 0.1-2 J / cm 2 .

[0244] At this time, the thickness of the hard coating layer may be specifically 1-10 μm, more specifically 3-10 μm. When the thickness of the hard coating layer is within the above range, excellent hardness, bending resistance, and curling characteristics may be obtained.

[0245] One embodiment of the present invention relates to an image display device having the above-described optical laminate. For example, the optical laminate of the present invention can be used as a window for an image display device, particularly a flexible display, a foldable display, a rollable display, or a stretchable display. In addition, the optical laminate of the present invention can be used by attaching it to a polarizing plate, a touch sensor, or the like.

[0246] The optical laminate according to one embodiment of the present invention can be used for reflective, transmissive and transflective LCDs, or LCDs of various drive types, such as TN, STN, OCB, HAN, VA and IPS. The optical laminate according to one embodiment of the present invention can also be used for various image display devices, such as plasma displays, field emission displays, organic EL displays, inorganic EL displays, electronic paper, etc.

[0247] One embodiment of the present invention relates to a transmittance-tunable optical stack including the optical stack described above.

[0248] The transmittance adjustable optical stack has a stacked structure in which a polarizing plate and a liquid crystal layer are provided inside, and transparent members are provided outside on both sides to protect the polarizing plate and the liquid crystal layer. In the transmittance adjustable optical stack according to the present invention, the above optical stack is used as the transparent member.

[0249] Furthermore, one embodiment of the present invention relates to a smart window including an optical layer stack having tunable light transmittance.

[0250] Hereinafter, the present invention will be described in more detail by way of examples, comparative examples and experimental examples. These examples, comparative examples and experimental examples are only intended to illustrate the present invention, and it is obvious to those skilled in the art that the scope of the present invention is not limited thereto.

[0251] Preparation Example 1: Preparation of a composition for forming a primer layer

[0252] After 22.67 wt% of an aqueous polyurethane dispersion (hereinafter referred to as PUD) (T&L, Akuarane 3410, 30 wt% solids), 77.08 wt% of ethanol and 0.1 wt% of a silicone-based leveling agent (BYK, BYK-333) were diluted with a stirrer, 0.075 wt% of a primary stabilizer (Adeka, STAB AO-80) and 0.075 wt% of a secondary stabilizer (Adeka, STAB 135A) were further added and stirred to prepare a composition for forming a primer layer.

[0253] Preparation Example 2-1: Preparation of a composition for a base resin layer

[0254] Under a nitrogen atmosphere, 14.67 g (45.8 mmol) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and 233.3 g of N,N-dimethylacetamide (DMAc) with a water content adjusted to 200 ppm were added to a 1 L separable flask equipped with a stirring blade, and the TFMB was dissolved in the DMAc by stirring at room temperature. Next, 4.283 g (13.8 mmol) of 4,4'-oxydiphthalic dianhydride (OPDA) was added to the flask and stirred at room temperature for 16.5 hours. Then, 1.359 g (4.61 mmol) of 4,4'-oxybis(benzoyl chloride) (OBBC) and 5.609 g (27.6 mmol) of terephthaloyl chloride (TPC) were added to the flask and stirred at room temperature for 1 hour. Next, 4.937 g (48.35 mmol) of anhydrous acetic acid and 1.501 g (16.12 mmol) of 4-methylpyridine were added to the flask, stirred at room temperature for 30 minutes, then heated to 70° C. using an oil bath and stirred for 3 hours to obtain a reaction solution.

[0255] After the resulting reaction solution was cooled to room temperature, 360 g of methanol and 170 g of ion-exchanged water were added to obtain a polyamide-imide precipitate. This was immersed in methanol for 12 hours, recovered by filtration, and washed with methanol. Next, the precipitate was dried under reduced pressure at 100°C to obtain a polyamide-imide resin.

[0256] N,N-dimethylacetamide (DMAc) was added to the obtained polyamideimide resin to a concentration of 15 wt % to prepare a composition for forming a base resin layer.

[0257] Preparation Example 2-2: Preparation of a composition for forming a base resin layer

[0258] Under a nitrogen atmosphere, 45 g (140.5 mmol) of 2,2-bis(trifluoromethyl)benzidine (TFMB) and 600.9 g of N,N-dimethylacetamide (DMAc) with a water content adjusted to 200 ppm were added to a 1 L separable flask equipped with a stirring blade. The TFMB was dissolved in the DMAc by stirring at room temperature. Next, 4.14 g (14.1 mmol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to the flask and stirred at room temperature for 2.5 hours. Then, 25.01 g (56.3 mmol) of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride was added and stirred at room temperature for 15 hours. Then, 4.15 g (14.1 mmol) of 4,4'-oxybis(benzoyl chloride) (OBBC) and 11.43 g (56.3 mmol) of terephthaloyl chloride (TPC) were added to the flask and stirred at room temperature for 1 hour. Next, 21.55 g (211.1 mmol) of anhydrous acetic acid and 3.28 g (35.2 mmol) of 4-methylpyridine were added to the flask and stirred at room temperature for 30 minutes. The mixture was then heated to 70°C in an oil bath and stirred for an additional 3 hours to obtain a reaction solution.

[0259] After the resulting reaction solution was cooled to room temperature, 647 g of methanol and 180 g of ion-exchanged water were added to obtain a polyamide-imide precipitate. This was immersed in methanol for 12 hours, recovered by filtration, and washed with methanol. Next, the precipitate was dried under reduced pressure at 100°C to obtain a polyamide-imide resin.

[0260] N,N-dimethylacetamide (DMAc) was added to the obtained polyamideimide resin to a concentration of 15 wt % to prepare a composition for forming a base resin layer.

[0261] Preparation Example 3: Preparation of hard coating composition

[0262] 23 parts by weight of hexafunctional urethane acrylate (UA-306I, Kyoeisha), 23 parts by weight of dendritic acrylate (Miramer SP1106, Miwon Specialty Chemicals), 50 parts by weight of methyl ethyl ketone, 3.5 parts by weight of 1-hydroxycyclohexyl phenyl ketone, and 0.5 parts by weight of a fluorine-based UV-curable functional group-containing compound (KY-1203, Shin-Etsu Silicones) were mixed using a stirrer and filtered using a PP filter to prepare a hard coating composition.

[0263] Preparation Example 4: Preparation of adhesive sheet

[0264] A monomer mixture containing 40 wt% 2-ethylhexyl acrylate (2-EHA), 40 wt% isobornyl acrylate (IBOA), 10 wt% dihydrodicyclopentadienyl acrylate (DCPA), and 10 wt% 2-hydroxyethyl acrylate (2-HEA) was adjusted to 20 wt% solids and placed in a 1 L reactor with ethyl acetate (EA) as the solvent.

[0265] Oxygen was removed by purging with nitrogen for 1 hour and maintained at 80° C. After the monomer mixture was uniformly mixed, 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 8 hours to prepare an acrylic random copolymer.

[0266] An adhesive composition was prepared by adding 10 parts by weight of an adhesion-imparting agent CL-467 (trimethylolpropane tris(2-methyl-1-aziridine propionate), Menadiona) and 0.1 parts by weight of a silane coupling agent KBM-403 (3-glycidoxypropyltrimethoxysilane, Shin-Etsu) to 100 parts by weight of the acrylic random copolymer prepared in this manner, and stirring for 30 minutes.

[0267] The prepared adhesive composition was applied on a 75 μm release film coated with a silicone release agent to a thickness of 25 μm after drying, dried at 120° C. for 5 minutes, and then laminated with a 75 μm release film coated with a silicone release agent to prepare an adhesive sheet.

[0268] Examples 1-4 and Comparative Examples 1-3: Production of Optical Laminated Bodies

[0269] use Figure 1 The laminated structure shown produces an optical stack.

[0270] As a glass substrate, ultrathin glass having the thickness shown in Table 2 below was prepared.

[0271] To dip-coat the four sides of the ultra-thin glass, a certain amount of the composition for forming the primer layer of Preparation Example 1 was filled into a water bath. All four sides of the ultra-thin glass were immersed in the composition for forming the primer layer of Preparation Example 1 to a depth of approximately 1 mm, then immediately removed and dried in an oven at 120°C for 2 minutes to form a primer layer having a thickness after drying as shown in Table 2 below.

[0272] Afterwards, a 25 μm heat-sensitive adhesive (Nitta, CS2325NA4) was bonded to one surface of the ultrathin glass, which was then adhered to a reinforced glass having a thickness of 3T and greater than the glass substrate. The composition for forming a primer layer according to Preparation Example 1 was then applied to the other surface of the ultrathin glass to a thickness shown in Table 2 below after drying, and dried in an oven at 120°C for 2 minutes to form a primer layer on the upper surface of the ultrathin glass.

[0273] Then, the composition of the base resin layer formed in Preparation Example 2-1 was applied on the primer layer using a coater to cover the top and side surfaces of the primer layer so that the thickness after drying was the thickness shown in Table 2 below, and dried in an oven at 80° C. for 1 hour and in an oven at 210° C. for 1 hour to form a base resin layer.

[0274] Thereafter, the hard coating composition of Preparation Example 3 was applied to the upper surface of the base resin layer so that the thickness after drying was the thickness shown in Table 2 below, and dried in an oven at 80° C. for 2 minutes and heated under a nitrogen atmosphere at a cumulative dose of 600 mJ / cm 2 UV light irradiation to form a functional coating.

[0275] The optical stack was then placed on a plate at -20°C for 5 minutes to reduce the adhesion of the heat-sensitive adhesive and to facilitate peeling from the reinforced glass. The functional coating was then cut using a CO2 laser (LCP-C600, Laser & Physics) at 30% power and a speed of 700 mm / s, offset 500 μm from the end of the ultrathin glass, to produce an optical stack with protected side surfaces.

[0276] [Table 2]

[0277]

[0278] Example 5: Production of an optical laminate

[0279] An optical layered body was manufactured by performing the same method as in Example 3, except that the composition for forming the base resin layer of Preparation Example 2-2 was used instead of the composition for forming the base resin layer of Preparation Example 2-1.

[0280] Example 6: Production of an optical laminate

[0281] use Figure 2 The laminated structure shown produces an optical stack.

[0282] As a glass substrate, ultra-thin glass with a thickness of 90 μm was prepared.

[0283] To dip-coat the four sides of the ultra-thin glass, a water bath was filled with a predetermined amount of the composition used to form the primer layer of Preparation Example 1. All four sides of the ultra-thin glass were immersed in the composition used to form the primer layer of Preparation Example 1 to a depth of approximately 1 mm. The glass was then immediately removed and dried in an oven at 120°C for 2 minutes to form a primer layer with a thickness of 0.5 μm after drying.

[0284] A 25 μm heat-sensitive adhesive (Nitta, CS2325NA4) was then bonded to one surface of the ultrathin glass, which was then adhered to a reinforced glass substrate having a thickness of 3T and greater than the glass substrate. The composition for forming a primer layer according to Preparation Example 1 was then applied to the other surface of the ultrathin glass to a thickness of 0.5 μm after drying, and dried in an oven at 120°C for 2 minutes to form a primer layer on the upper surface of the ultrathin glass.

[0285] Then, the composition of the base resin layer formed in Preparation Example 2 was applied on the primer layer using a coater to cover the top and side surfaces of the primer layer so as to have a thickness of 12 μm after drying, and the base resin layer was formed by drying in an oven at 80° C. for 1 hour and in an oven at 210° C. for 1 hour.

[0286] The optical laminate was then placed on a plate at -20°C for 5 minutes to reduce the adhesion of the heat-sensitive adhesive so as to be peeled off from the reinforced glass. Thereafter, the reinforced glass was bonded to the base resin layer using a heat-sensitive adhesive.

[0287] Then, a primer layer was formed on the remaining surface of the ultrathin glass in the same manner as above to form a thickness of 0.5 μm after drying, and then a base resin layer was formed to form a thickness of 11.5 μm after drying.

[0288] Thereafter, the hard coating composition of Preparation Example 3 was applied to the base resin layer present on the upper surface of the glass substrate to have a thickness of 5 μm after drying, dried in an oven at 80° C. for 2 minutes, and heated under a nitrogen atmosphere at a cumulative dose of 600 mJ / cm 2 UV light irradiation to form a functional coating.

[0289] Finally, the optical stack was placed on a plate at -20°C for 5 minutes to reduce the adhesion of the heat-sensitive adhesive and to facilitate peeling from the reinforced glass. The functional coating was then cut using a CO2 laser (LCP-C600, Laser & Physics) at 30% power and a speed of 700 mm / s, offset 500 μm from the end of the ultra-thin glass, to produce an optical stack with protected side surfaces.

[0290] Comparative Example 4: Production of an Optical Laminated Body

[0291] As a glass substrate, ultra-thin glass with a thickness of 90 μm was prepared.

[0292] The hard coating composition of Preparation Example 3 was applied to a 30 μm thick polyamideimide film (PAI, Sumitomo Chemical) so that the thickness after drying was 5 μm, and dried in an oven at 80° C. for 2 minutes and heated under a nitrogen atmosphere at a cumulative dose of 600 mJ / cm 2 UV light irradiation to form a functional coating.

[0293] Next, the release film of the adhesive sheet of Preparation Example 4 was peeled off and adhered to the surface of the polyamide-imide film not having the functional coating formed thereon using a laminator. The functional coating film including the adhesive layer thus produced was cut to a size 1 mm larger than the size of the glass substrate using a supercutter, and the remaining release film was peeled off and adhered to one surface of the glass substrate using a laminator to produce an optical laminate including the glass substrate.

[0294] Comparative Example 5: Production of an Optical Laminated Body

[0295] As a glass substrate, ultra-thin glass with a thickness of 90 μm was prepared.

[0296] The composition for forming the primer layer of Preparation Example 1 was applied to one surface of the ultra-thin glass to a thickness of 0.5 μm after drying, and dried in an oven at 120°C for 2 minutes to form a primer layer. Then, the composition of the base resin layer formed in Preparation Example 2 was applied on the primer layer using a coater to form a thickness of 20 μm after drying, and dried in an oven at 80°C for 1 hour, and dried in an oven at 210°C for 1 hour to form a base resin layer. Then, the hard coating composition of Preparation Example 3 was applied to the base resin layer to form a thickness of 5 μm after drying, dried in an oven at 80°C for 2 minutes, and heated to a cumulative dose of 600 mJ / cm under a nitrogen atmosphere. 2 A functional coating is formed by irradiating the glass substrate with UV light to produce an optical laminate including the glass substrate.

[0297] Experimental Example 1:

[0298] The properties of the optical laminates produced in the above-described Examples and Comparative Examples were measured by the following methods, and the results are shown in Tables 3 and 4 below. Furthermore, the value of d2 / d1 was calculated and shown in Table 3 below, where d1 is the thickness of the glass substrate and d2 is the total thickness of the primer layer, base resin layer, and functional coating layer. Furthermore, the total thickness of the optical laminate was also calculated and shown in Table 3 below.

[0299] (1) Elastic modulus of the base resin layer

[0300] Each composition for forming a base resin layer of Preparation Examples 2-1 to 2-2 was applied to glass using an applicator to have a thickness of 20 μm after drying. The base resin layer was then formed by drying in an oven at 80° C. for 1 hour and in an oven at 210° C. for 1 hour. The base resin layer was then peeled off to obtain only the base resin layer.

[0301] The obtained resin layer was made into a test specimen for tensile evaluation using a supercutter according to JIS-K7139 bar type specification. The elastic modulus (GPa) of the specimen was measured at a tensile speed of 4 mm / min in a universal testing machine in tensile evaluation mode.

[0302] (2) Pencil hardness

[0303] After fixing the optical laminate with the hard coating layer facing upward, the pencil hardness was measured under a load of 750 gf. Five 1 cm length tests were performed using a pencil having the same hardness, and the hardness that was OK four or more times was expressed as the pencil hardness.

[0304] Furthermore, the pencil hardness measurement indicates "OK" if the glass substrate of the optical laminate is not broken under a load of 750 gf, and indicates "NG" if it is broken.

[0305] (3) Bending resistance

[0306] A mandrel test was performed with a curvature radius of 3 mm to observe whether the optical laminate was broken when the hard coating layer was folded inward. The bending resistance was evaluated according to the following evaluation criteria.

[0307] <Evaluation Criteria>

[0308] OK: The optical laminate is not broken

[0309] NG: The optical laminate is broken

[0310] (4)Curling characteristics

[0311] An optical laminate measuring 10 cm×10 cm was produced, and the degree of lifting of each corner from the ground was measured after standing at 25° C., 48 RH % for 24 hours. The curling characteristics were evaluated according to the following evaluation criteria.

[0312] <Evaluation Criteria>

[0313] OK: The average height of the four corners is 3 mm or less.

[0314] NG: The average height of the four corners is greater than 3 mm.

[0315] (5) Coating uniformity in the boundary area

[0316] The total thickness of the primer layer, base resin layer and functional coating layer excluding the glass substrate was measured using a thickness gauge to obtain coating uniformity (%) according to equation (2) below. The coating uniformity of the boundary area was evaluated according to the following evaluation criteria.

[0317] [Equation 2]

[0318]

[0319] Where a is the average thickness of the four central points, and b is the average thickness of the four corner points in the boundary area.

[0320] The boundary region refers to a region within 3 mm from the end of the glass substrate.

[0321] <Evaluation Criteria>

[0322] OK: The coating uniformity (%) value is 10% or less.

[0323] NG: The coating uniformity (%) value exceeds 10%.

[0324] (6) Side protection

[0325] The side surfaces of the optical laminate were observed under an optical microscope to confirm the presence of the coating layer and evaluated according to the following evaluation criteria.

[0326] <Evaluation Criteria>

[0327] ○: Coating on the side

[0328] ×: No coating on the side

[0329] (7) Shatterproof performance

[0330] A 0.7 mm ballpoint pen (Monami, FX Zeta) was dropped in free fall from 10 cm above the optical laminate and impacted the boundary area (area within 3 mm from the end of the glass substrate) to check whether the glass substrate was broken and evaluated according to the following evaluation criteria.

[0331] <Evaluation Criteria>

[0332] OK: There is no cracking in the boundary region of the glass substrate, or even in the case of cracking, the cracked fragments (chips) are fixed to the base resin layer and the functional coating layer and are not shattered.

[0333] NG: The boundary region of the glass substrate is broken, and the broken pieces (chips) are peeled off from the base resin layer or the functional coating layer and broken.

[0334] [Table 3]

[0335]

[0336] [Table 4]

[0337] Coating uniformity in edge areas Side protection Shatterproof performance Example 1 OK ○ OK Example 2 OK ○ OK Example 3 OK ○ OK Example 4 OK ○ OK Example 5 OK ○ OK Example 6 OK ○ OK Comparative Example 1 OK ○ NG Comparative Example 2 OK ○ OK Comparative Example 3 OK ○ OK Comparative Example 4 - X OK Comparative Example 5 NG X NG

[0338] As shown in Table 3 above, it can be seen that Examples 1-6, in which a primer layer, a base resin layer, and a functional coating layer are formed on the ultra-thin glass according to the present invention having a thickness of less than 100 μm, such that a ratio d2 / d1 of the total thickness d2 of the primer layer, the base resin layer, and the functional coating layer to the thickness d1 of the glass substrate is controlled to be 0.1-0.4, have excellent pencil hardness characteristics while ensuring bending resistance and curling characteristics.

[0339] On the other hand, as shown in Table 3 above, the optical laminate of Comparative Example 1, which had a d2 / d1 value of less than 0.1, had poor hardness characteristics, such that the lower glass substrate cracked when the pencil hardness characteristics were measured, and the optical laminate of Comparative Example 3, which had a d2 / d1 value of greater than 0.4, could not simultaneously ensure pencil hardness characteristics, bending resistance, and curling characteristics. In addition, it was found that the optical laminate of Comparative Example 2 (wherein the total thickness of the optical laminate was 120 μm or more) could not ensure bending resistance.

[0340] Furthermore, as shown in Table 4 above, it can be seen that the optical laminates of Examples 1 to 6 having a structure in which a primer layer is formed on a glass substrate so as to cover the upper surface and side surfaces of the glass substrate according to the present invention, and a base resin layer is formed on the primer layer so as to cover the upper surface and side surfaces of the primer layer, have excellent coating uniformity in the boundary region and protect the side surfaces of the glass substrate, thereby preventing the glass substrate from being broken due to external impact applied to the side surfaces, or even if it is broken, preventing the breakage of glass fragments.

[0341] On the other hand, as shown in Table 4 above, the optical laminate of Comparative Example 5 having a structure in which the primer layer is formed only on the upper surface of the glass substrate and the resin layer is formed only on the upper surface of the primer layer has poor coating uniformity in the boundary area, and the side surfaces of the glass substrate are not protected, so that the glass substrate is broken due to external impact applied to the side surfaces, or even if broken, shattering of glass fragments occurs.

[0342] Meanwhile, as shown in Tables 3 and 4 above, it can be seen that in the optical laminate of Comparative Example 4, in which the functional coating film is bonded to the glass substrate via an adhesive layer, the side of the glass substrate is not protected, the total thickness of the optical laminate is greater than 120 μm, and the pencil hardness is reduced.

[0343] Although specific embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that these specific embodiments are not intended to limit the invention to the preferred embodiments, and it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

[0344] Accordingly, the scope of the invention is defined by the following claims and their equivalents.

Claims

1. An optical laminate comprising: Glass substrate; a primer layer formed on the glass substrate to cover the upper surface and side surfaces of the glass substrate; a base resin layer formed on the primer layer to cover the upper surface and side surfaces of the primer layer; and A functional coating is formed on the base resin layer, wherein The glass substrate is ultra-thin glass with a thickness of less than 100 μm. The optical stack has a pencil hardness of 2H or greater throughout the optical stack, and The optical stack satisfies equation (1): [Equation 1] 0.1≤d2 / d1≤0.4 in, d1 is the thickness of the glass substrate, and d2 is the total thickness of the primer layer, base resin layer and functional coating layer.

2. The optical laminate according to claim 1, wherein The primer layer is formed to cover the entire surface of the glass substrate.

3. The optical laminate according to claim 2, wherein The base resin layer is formed to cover the entire surface of the primer layer.

4. The optical laminate according to claim 1, wherein The total thickness of the optical stack is less than 120 μm. The optical laminate according to claim 1 , wherein The primer layer is formed from a composition for forming a primer layer, wherein the composition for forming a primer layer includes an aqueous polyurethane resin and a stabilizer, wherein the stabilizer includes a primary thermal stabilizer and a secondary thermal stabilizer. The optical layered body according to claim 5 , wherein: The primary heat stabilizer is at least one selected from phenolic heat stabilizers and amine heat stabilizers, and the secondary heat stabilizer is at least one selected from phosphorus heat stabilizers and sulfur heat stabilizers.

7. The optical layered body according to claim 1, wherein The base resin layer is formed of a composition for forming a base resin layer, and the composition for forming a base resin layer includes at least one resin of a polyimide resin and a polyamideimide resin.

8. The optical layered body according to claim 1, wherein The base resin layer has an elastic modulus of 3.3 to 5.2 GPa.

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