KR102395800B1 - Flexible Cover Window with Complex Pattern - Google Patents

Abstract

The present invention relates to a flexible cover window, comprising: a flat portion formed to correspond to the flat area of a flexible display; A flexible cover window and a method for manufacturing the same, characterized in that a composite pattern comprising a pattern for impact compensation and a nano-pattern superimposed on the pattern for impact compensation is formed on the glass substrate, and a method for manufacturing the same. As a result, a composite pattern consisting of a pattern for impact compensation and a nano-pattern with different scales is formed on the glass substrate to improve surface scratches, disperse impact force to improve impact resistance, and flexible with strength characteristics and folding characteristics It provides a cover window.

Description

Flexible Cover Window with Complex Pattern

The present invention relates to a flexible cover window, and to a flexible cover window in which strength characteristics and folding characteristics are secured by implementing a composite pattern on a glass substrate, improving the surface, and dispersing impact force.

In recent years, electrical and electronic technologies are rapidly developing, and various types of display products are emerging to meet the needs of the new era and the needs of various consumers.

In the case of a flexible display, research is being conducted in the form of basically bending, rolling, and stretching starting from folding, and a cover window for protecting the display panel as well as the display panel must be formed to be flexible.

Such a flexible cover window should basically have good flexibility, and should not cause marks on the folding part even when repeatedly folding, and there should be no distortion of image quality.

For the cover window of the existing flexible display, a polymer film such as PI or PET film has been used on the surface of the display panel.

However, in the case of a polymer film, the mechanical strength is weak, and it merely serves to prevent scratches on the display panel, but it is weak in impact resistance, has low transmittance, and is known to be relatively expensive.

In addition, in the case of such a polymer film, as the number of folds of the display increases, marks are left on the foldable portion, resulting in damage to the foldable portion. For example, pressing or tearing of the polymer film occurs during the evaluation of the folding limit (normally 200,000 times).

Recently, various studies on glass-based cover windows have been made in order to overcome the limitations of polymer film cover windows.

In the case of such a glass-based cover window, basic required properties such as satisfying folding characteristics, no screen distortion, and sufficient strength even in repeated contact with a touch pen and constant pressure are required.

In order to satisfy the strength characteristics of the cover window, the glass must have a certain thickness or more, whereas to satisfy the folding characteristics, the glass must be less than a certain thickness. Research on the optimal cover window thickness and structure is required.

In addition, since the inherent texture of tempered glass is deteriorated when the glass is less than a certain thickness, this point must be taken into consideration.

Accordingly, there is a need for a technology for providing a cover window that maintains the inherent texture of tempered glass, maintains an appropriate thickness for securing strength, and at the same time satisfies folding characteristics.

In addition, it is difficult to provide a high-quality cover window because the process for removing scratches on the glass surface due to the use of thin glass is very cumbersome and difficult.

In order to satisfy the strength characteristics and folding characteristics of a cover window using thin glass, an attempt has been made to form a specific pattern on the glass in the prior art.

The photolithography process is mainly performed as a process for forming a pattern on such a thin glass plate, but it is very difficult to handle the thin plate glass, and in the case of the optical patterning process, there are limitations in exposure resolution and image resolution. This is a difficult situation.

Korean Patent Office Publication No. 10-2017-0122554 (foldable display device).

An object of the present invention is to provide a high-quality flexible cover window in which strength characteristics and folding characteristics are secured by forming a composite pattern on a glass substrate, improving the surface, and dispersing impact force.

In order to achieve the above object, in a flexible cover window comprising a flat portion formed to correspond to a flat area of a flexible display, and a folding portion formed to be connected to the flat portion and formed to correspond to a folding area of the flexible display, the glass substrate Another technical subject is a flexible cover window, characterized in that a composite pattern comprising a pattern for impact compensation and a nano-pattern superimposed on the pattern for impact compensation is formed.

The present invention relates to a flexible cover window, and by forming a composite pattern consisting of a pattern for impact compensation and a nano-pattern having different scales on a glass substrate to disperse the impact force to improve impact resistance, and to secure strength and folding properties It relates to a flexible cover window.

In particular, as a nanopattern is formed on a glass substrate on which a pattern for impact compensation is formed from a nanopatterning process using a phase separation phenomenon of a heterogeneous polymer structure, there is an advantage in that the formation and control of the nanopattern is easy.

As described above, by implementing the folding part or the folding part and the flat part including the composite pattern on the glass substrate, the impact is dispersed during pen-drop impact to increase the rigidity against the pen-drop, and strength characteristics and folding characteristics are satisfied at the same time.

In addition, the present invention provides a high-quality flexible cover window by improving scratches on the surface of a glass substrate according to the formation of a composite pattern.

In addition, the present invention is implemented as a composite material of glass and resin material, so that flexibility, restoring force, elasticity and strength characteristics by the resin material are reinforced while maintaining the texture of the glass as much as possible. It is intended to provide a flexible cover window implemented with a composite material that further improves impact resistance by absorbing and prevents the composite pattern from being visually recognized from the outside.

1 to 6 - A schematic diagram showing a method of manufacturing a flexible cover window according to various embodiments of the present invention.
7 to 9 - A view showing a schematic diagram of a flexible cover window according to various embodiments of the present invention.
10 - A view showing an electron micrograph of the surface of the flexible cover window according to an embodiment of the present invention.

The present invention relates to a flexible cover window, and by forming a composite pattern consisting of a pattern for impact compensation and a nano-pattern having different scales on a glass substrate to improve surface scratches, disperse impact force, improve impact resistance, and strength It relates to a flexible cover window with secured characteristics and folding characteristics.

In particular, the present invention forms a pattern for regular or irregular impact compensation on a glass substrate by a general dry or wet etching process, and implements a nanopattern using phase separation between heterogeneous polymer structures to improve scratches and further increase impact force It relates to a flexible cover window in which strength characteristics and folding characteristics are secured by effectively dispersing, and a method for manufacturing the same.

That is, by implementing a composite pattern on the folding part or the folding part and the flat part of the glass substrate, the share of scratches is lowered and the impact is dispersed during pendrop impact to increase the rigidity against the pendrop, thereby improving the strength and folding characteristics. at the same time to satisfy.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 to 6 are schematic views showing a method of manufacturing a flexible cover window according to various embodiments of the present invention, and FIGS. 7 to 9 are schematic views showing a flexible cover window according to various embodiments of the present invention. 10 is a view showing an electron micrograph of the surface of the flexible cover window according to an embodiment of the present invention.

The scale in the drawings of the present invention may be expressed exaggerated or enlarged for convenience of description, but is not limited thereto.

As shown, the manufacturing method of the flexible cover window 100 according to the present invention includes a flat portion (P) formed to correspond to the flat area of the flexible display, and the flat portion (P) connected to, and folding of the flexible display A method of manufacturing a flexible cover window including a folding part (F) formed to correspond to a region, the method comprising: a first step of providing a glass substrate (110); and a polymer including a heterogeneous polymer structure on the glass substrate (110) A second step of forming a layer, a third step of inducing phase separation between the heterogeneous polymer structures included in the polymer layer, and selectively removing any one of the polymer structures from the phase-separated polymer layers to obtain the glass substrate 110 ) of the fourth step of forming a mask pattern layer made of a residual polymer structure on the surface and using the mask pattern layer as an etching mask to form a nanopattern 122 in the entire area of the flat portion P and the folding portion F a fifth step, wherein the glass substrate 110 on which the pattern 121 for impact compensation is formed in the first step is provided, or the glass substrate 110 is impacted after the nanopattern 122 is formed in the fifth step A compensating pattern 121 is formed to form a composite pattern 120 including a shock compensating pattern 121 on the glass substrate 110 and a nanopattern 122 superimposed on the shock compensating pattern 121 . ) as a technical gist of the manufacturing method of the flexible cover window in which the composite pattern 120 is implemented, characterized in that the forming.

In the present invention, the folding area of the display refers to an area in which the display is folded or bent in half, and the area in which the cover window 100 is folded corresponding to this area is referred to as the "folding part" of the cover window 100 in the present invention ( It is referred to as F), and a flat area excluding the folding portion F is referred to as a “planar portion” (P) of the cover window 100 .

In particular, the present invention is formed based on glass, and the folding part (F) is formed on the same plane as the plane part (P) and has the same physical and chemical properties, or physical or chemical addition to the plane part (P) By performing the process, the shape, thickness, physical or chemical properties may be formed differently.

Preferably, the folding portion F is formed by slimming to a thinner thickness than the flat portion P. In general, the thickness of the flat portion P of the cover window 100 is 50 ~300㎛, the thickness of the folding portion (F) is about 10 ~ 100㎛, to form a folding portion (F) by processing a very thin glass plate.

Here, the folding portion F may have a uniform thickness or may be formed to gradually increase in thickness from the center of the folding area toward the outside. That is, the folding part F may be formed in a straight or curved shape.

When the folding part (F) is formed in a straight shape, folding characteristics are further improved compared to the technology formed in a curved shape. When folded, the folding characteristics are deteriorated, such as cracking when folded in a thick part, but when the folding part (F) has a uniform thickness as a whole, that is, when it is formed in a straight shape with the same thickness, the area making the minimum thickness is formed widely and flexible , restoring force and elasticity are improved to improve folding characteristics.

In addition, it is not easy to align the center of the curved folding part (F) when assembling mechanically, but the folding part (F) according to the present invention has a uniform thickness, so that when assembling mechanically, that is, the front surface of the display panel It is possible to reduce the assembly tolerance when joining to the product, thereby minimizing the quality difference between products and reducing the defect rate.

As described above, the advantages of the straight folding part (F) are more than those of the curved folding part (F), but it can be manufactured by selecting the straight folding part (F) or the curved folding part (F) according to the specifications of the product. .

Here, the width of the folding part (F ) is designed in consideration of the radius of curvature when the cover window 100 is folded. The thickness of the window 100 is formed in a range of 10 to 100 μm, which is related to the folding part (F).

If the depth of the folding part F is too deep, that is, if the folding area of the cover window 100 is too thin, foldability is good, but wrinkles or strength are disadvantageous during reinforcement, and when it is formed too thickly, flexibility in the folding area , the restoring force and the elastic force are reduced, so that the folding characteristics are deteriorated, the thickness of the cover window 100 in the folding part (F) is suitable about 10 ~ 100㎛.

The cover window 100 in the present invention is formed with a thickness of about 50 to 300 μm on a glass basis, and at this thickness, the width and depth of the folding part F are appropriately designed as described above. If it is thinner than the thickness, the thickness of the folding area of the cover window 100 becomes too thin after the formation of the folding part F, and thus the above problems occur. And the elasticity is lowered, which causes trouble in reducing the weight of the display product.

In one embodiment of the present invention, the folding part F and the flat part P form the same plane, or in another embodiment, in the form of being slimmed inward in the folding area of the cover window 100 It is formed in a rectangular trench (Trench) shape as a whole, and at both ends of the folding part (F), inclined parts whose thickness is gradually increased in the folding part (F) are formed to lead to the planar area of the cover window (100). It can be formed to be

In particular, by forming a slope with a low inclination on both ends (the boundary with the flat part P) of the folding part F, the size of the reflection angle by the reflective surface is similarly adjusted in the entire area of the folding part F to prevent light interference and anti-reflection. This is to minimize the visual visibility on the slope.

The present invention is formed on the front surface of the display panel to protect the display panel by maintaining the folding characteristics and strength characteristics, and is disposed on the CPI (clear polyimide) cover to protect the CPI cover.

As described above, the present invention is formed on a glass basis and intends to provide a flexible cover window 100 that has strength characteristics and folding characteristics while being thin so that it can be applied to a flexible display. In order to provide a flexible cover window 100 with reinforced characteristics, it is characterized in that the composite pattern 120 is formed in the entire area of the folding part (F) or the flat part (P) and the folding part (F). .

As a method for manufacturing the composite pattern 120 on the glass substrate 110 according to the present invention, as shown in FIGS. 1 to 6 , the glass substrate 110 is first provided (first step).

The glass substrate 110 is prepared according to product specifications, such as unprocessed raw glass, tempered glass, slimming processing of the folding part F, or glass having a specific pattern formed on the folding part F, and the like.

The present invention can be largely carried out by the manufacturing method according to two embodiments. A flexible cover window provided with a composite pattern 120 is provided by forming a nanopattern 122 on the glass substrate 110 on which the pattern 121 for impact compensation is formed, or a glass substrate on which the nanopattern 122 is formed ( The process of providing the flexible cover window provided with the composite pattern 120 by forming the pattern 121 for impact compensation on the 110 ) may proceed.

First, a process of forming the nanopattern 122 on the glass substrate 110 on which the pattern 121 for impact compensation is formed as shown in FIGS. 1 to 3 will be described first.

The impact compensation pattern 121 continuously forms periodic or aperiodic patterns by dry or wet etching the glass substrate 110, and includes the folding part F or the flat part P and the folding part ( F) It is formed over the entire region, and is preferably formed to be less than half the thickness of the glass substrate 110 .

In general, when the flexible cover window 100 is to be implemented using a glass material, the thickness of the glass substrate 110 should be thin, and a predetermined thickness or more to secure strength characteristics.

For example, when the radius of curvature must satisfy at least 0.5 mm or more during folding, the thickness of the cover window 100 may be 200 μm or less, preferably 20 to 100 μm, in this case, a Pen-Drop When an object with a narrow cross-sectional area, such as the one shown above, is impacted on the upper surface (front) of the glass substrate 110 , deformation and damage to the entire glass substrate 110 may be applied centered on the pendrop contact portion.

In the case of the existing cover window 100 having a slimmed folding area, the thickness of the portion is particularly thin, so pendrop characteristics are very weak, and a stress difference occurs due to the difference in thickness between the folding area and the planar area, so that the glass substrate (110) The problem such as waveness (Waveness) is added together, there is a disadvantage that is very vulnerable to impact resistance.

The present invention provides a pattern 121 for impact compensation on one or both surfaces of the glass substrate 110, partially or wholly, in order to improve impact resistance through the improvement of pendrop characteristics and, at the same time, improve folding characteristics and strength characteristics. It may be formed in the folding part (F) or the flat part (P) and the folding part (F).

That is, when a pendrop impact is applied to the glass substrate 110 , the impact force is transmitted to the inside of the glass substrate 110 and collides with or is absorbed by the impact compensation pattern 121 , so that the impact force is dispersed or absorbed. to make it possible

In addition, according to the present invention, the folding characteristics can be reinforced by the impact compensation pattern 121 formed entirely on the glass substrate 110 without forming the slimmed folding part, and stress due to the difference in thickness between the slimmed folding part and the flat part It is possible to resolve the difference, thereby improving impact resistance, and minimizing screen distortion or resolution degradation, thereby providing a high-quality flexible display.

In addition, in the present invention, the height of the pattern 121 for impact compensation is preferably formed to be less than half the thickness of the glass substrate 110 .

When the height is lower than the above range, the effect of impact force dispersion is insignificant, and when it is higher than this, the overall strength characteristics are deteriorated due to a decrease in the effective thickness.

In addition, the pattern density of the shock compensation pattern 121 formed on the folding part F and the pattern density of the shock compensation pattern 121 formed on the flat part P may be the same or substantially similar.

Also, if necessary, the pattern density of the shock compensation pattern 121 formed on the folding part F may be formed more densely than the pattern density of the shock compensation pattern 121 formed on the flat part P.

Specifically, if the pattern density of the impact compensation pattern 121 formed on the flat portion P is about 10 to 50% with respect to the entire glass substrate 110, the impact formed on the folding portion F The pattern density of the compensation pattern 121 may be the same or substantially similar to this, or may be formed at a density of about 20 to 70% higher than this.

If the density of the impact compensation pattern 121 formed on the folding part F is higher than the above range, the strength may be lowered. Therefore, it is preferable to form the pattern density within the above range.

This is to further enhance the effect of dispersing the impact force while further supplementing the folding characteristics in the folding part (F).

In addition, the height of the pattern of the shock compensation pattern 121 formed on the folding part (F) and the height of the pattern of the shock compensation pattern 121 formed on the flat part (P) may be the same or almost the same. .

In addition, if necessary, the height of the pattern of the shock compensation pattern 121 formed on the folding part (F) may be lower than the height of the pattern of the shock compensation pattern 121 formed on the flat part (P). there is.

That is, in the folding part (F), the pattern density is higher, but the pattern height is formed to be lower, so that the pendrop characteristics and the strength characteristics can be improved at the same time, and the folding characteristics can also be improved.

In the shock compensation pattern 121, any one or more patterns of a spherical shape, a pyramidal shape, a cone shape, a polygonal pillar shape, and a cylindrical shape may be formed regularly or irregularly, and the height of each pattern may also be varied, so that the glass substrate. (110) to effectively distribute the impact force transmitted to the inside.

In addition, the pattern of the shock compensation pattern 121 has a larger outer horizontal cross-sectional area than the inner horizontal cross-sectional area, that is, the closer to the rear surface of the glass substrate 110, the wider the horizontal cross-sectional area is formed. This is to effectively dissipate the impact force transmitted to the outside.

The pattern 121 for impact compensation is wet etching, laser patterning, blasting, roller stamping, any one of, or a wet etching process after laser patterning, a wet etching process after blasting, and a roller After stamping, it may be formed by any one of the wet etching processes. Here, the roller stamping process is to form a pattern 121 for impact compensation by hot pattern roller stamping when forming glass in a glass drawing tower.

In one embodiment, photoresist or DFR is formed on the glass substrate 110, patterned to form a resist pattern layer, and using this as an etching mask, any one of wet etching, laser patterning, blasting, and roller stamping processes, or The pattern 121 for impact compensation is formed by performing any one of a wet etching process after laser patterning, a wet etching process after blasting, and a wet etching process after roller stamping.

When the impact compensation pattern 121 is formed on the entire area of the flat portion P and the folding portion F, a separate masking alignment process is not required, and is half the thickness of the glass substrate 110 . It is implemented by controlling the above etching process conditions so that it can be formed as follows.

In addition, in the pattern 121 for impact compensation according to another embodiment of the present invention, a stripe pattern or a stripe and space pattern may be repeatedly formed.

Here, the pattern 121 for impact compensation may be formed so that the interval between the pattern formed on the flat portion P and the pattern formed on the folding portion F is the same or almost similar.

In addition, in the pattern 121 for impact compensation, the spacing between the patterns formed on the folding portion F may be denser than that of the pattern formed on the flat portion P, and the direction of the stripe is along the folding line. to be formed, so that the pendrop characteristics, strength characteristics and folding characteristics can be supplemented.

By forming the pattern 121 for impact compensation on the glass substrate 110 in this way, the impact force is dispersed, and although the thickness of the glass substrate 110 as a whole is not reduced, the effective thickness is decreased, thereby improving the impact resistance against the pendrop. , and contributes to the folding properties and overall strength-increasing properties.

Then, a polymer layer including a heterogeneous polymer structure is formed on the glass substrate 110 on which the impact compensation pattern 121 is formed (second step).

The heterogeneous polymer structure is formed by bonding or mixing two or more polymers having different properties, and may be any polymer in which phase separation occurs, and is not particularly limited.

In one embodiment of the present invention, as the heterogeneous polymer structure, a block copolymer including a polymer A block and a polymer B block having two different properties or a polymer mixture including polymer A and polymer B is used. Such block copolymer or polymer mixture may be provided as a solution by further including a solvent. The solvent may be a solvent having different solubility for each polymer, or a solvent having the same solubility.

First, in the block copolymer, two or more chemically different blocks are covalently bonded, and the phase separation structure and size are different depending on the chemical properties of each block, the length (or molecular weight) of the block, and the composition ratio, annealing temperature, etc. do.

In addition, the polymer mixture is formed by mixing two or more chemically different polymers to form a heterogeneous mixture, and the phase separation structure and size are different depending on the chemical properties, molecular weight, mixing ratio, annealing temperature, etc. of each polymer.

In particular, the polymer A and the polymer B constituting the block copolymer or polymer mixture have different properties, that is, incompatibility. For example, the polymer A and the polymer B may have different solubility due to a difference in their respective chemical structures. As a result, the phase made of any one polymer has higher solubility than the phase made of another type of polymer, so that any one polymer can be selectively and easily removed.

Specifically, as the block copolymer, a polymer A block derived from styrene or a derivative thereof and a polymer B block derived from an acrylic acid ester are combined.

For example, the block copolymer is a polystyrene (PS)-polymethylmethacrylate (PMMA) block copolymer, a polystyrene (PS)-polybutadiene (PB) block copolymer, and a polystyrene (PS)-polydimethylsiloxane (PDMS) Any one of block copolymers can be used preferably.

In addition, specifically, the polymer mixture may be a heterogeneous mixture including a polymer A derived from styrene or a derivative thereof and a polymer B derived from an acrylic acid ester.

For example, the polymer mixture may include a polystyrene (PS)-polymethylmethacrylate (PMMA) polymer mixture, a polystyrene (PS)-polybutadiene (PB) polymer mixture, and a polystyrene (PS)-polydimethylsiloxane (PDMS) polymer mixture. Either one can be preferably used.

The polymer layer may be formed on the glass substrate 110 on which the impact compensation pattern 121 is formed, for example, by a process such as spin coating. A neutral layer treatment can be performed first on the surface of

The neutral layer is for effectively inducing phase separation of the vertical structure on the glass substrate 110 , and provides a neutral affinity without high affinity with any polymer constituting the heterogeneous polymer structure.

That is, the polymers have an equal affinity on the surface of the neutral layer, thereby advantageously forming a phase-separated structure forming a vertical structure on the glass substrate 110 .

The neutral layer may be formed of an organic material or an inorganic material layer. In the case of an inorganic material layer, the surface of the glass substrate may be hydrophobically treated by ion implantation to induce vertical alignment of individual polymer blocks. .

And, it induces phase separation between the heterogeneous polymer structures included in the polymer layer (third step).

Polymer block components in the block copolymer may be phase separated by reordering or phase separation by spontaneous rearrangement or annealing. That is, by annealing, etc., the region A in which the polymer A blocks are ordered and the region B in which the polymer B blocks are arranged may be phase-separated, and the shape of each region depends on the above-described chemical properties of each block and the length (or molecular weight) of each block. ), and the phase separation structure and size are different depending on the composition ratio, annealing temperature, etc.

The annealing temperature is generally higher than the glass transition temperature of the block copolymer, and may be performed at a temperature lower than the thermal decomposition temperature, for example, at about 100 to 190°C, and may be performed for several tens of seconds to 24 hours.

Region A composed of the polymer A block and region B composed of the polymer B block form various phase-separated structures according to each of the above-described chemical properties, block length, composition ratio, annealing temperature, etc., and by adjusting these conditions, region A and region B may serve as a matrix, and the other region may constitute a mask pattern layer, and region A constituting the matrix may be selectively removed in a subsequent process.

In addition, the case of the regions A and B phase-separated by the polymer A and the polymer B constituting the polymer mixture may be described in the same way.

Here, in the case of the block copolymer, a relatively regular region pattern may be implemented according to each condition, and in the case of the polymer mixture, a relatively irregular region pattern may be implemented according to each condition.

This is because in the case of a block copolymer, incompatible heterogeneous polymer blocks are covalently linked, so that a region composed of each polymer block is implemented relatively regularly through the phase separation process. As a system mixture, it is realized in a relatively irregular region pattern than in the case of the block copolymer.

Such a heterogeneous polymer block or a heterogeneous polymer has higher solubility in the polymer block or polymer constituting the region in which the polymer block or polymer is not removed for the formation of the nanopattern 122 in the subsequent process. , patterning is performed using the remaining polymer block or polymer as an etch mask.

* And, by selectively removing any one of the polymer structures from the phase-separated polymer layers, a mask pattern layer made of the remaining polymer structures is formed on the glass substrate 110 on which the impact compensation pattern 121 is formed (the second step). Step 4).

Any one of the polymer structures in the phase-separated polymer layer, that is, any one of the regions A and B, is removed, which depends on the shape of the nanopattern 122 to be finally formed, depending on the type of polymer, molecular weight, and mixing ratio. Alternatively, the polymer structure to be removed is designed by controlling the composition ratio, annealing temperature, and the like.

According to an embodiment of the present invention, after phase separation is induced using a polystyrene (PS)-polymethylmethacrylate (PMMA) block copolymer, PS or PMMA may be selectively removed.

For example, when PMMA is set as the matrix region, the phase separation region formed by PMMA can be removed through wet etching, thermal decomposition, UV treatment, etc. by using the solubility difference between PS and PMMA. Here, when thermal decomposition or UV treatment is performed, the low molecular weight PMMA is removed by a developing process or the like.

By selectively removing the region formed by the phase-separated polymer layer as described above, a mask pattern layer made of the remaining polymer structure is formed on the glass substrate 110 on which the impact compensation pattern 121 is formed.

Then, using the mask pattern layer as an etching mask, a nanopattern 122 is formed on the glass substrate 110 on which the impact compensation pattern 121 is formed (fifth step).

The nanopattern 122 is formed along the impact compensation pattern on the glass substrate 110 in a folding portion, or in the total area of the flat portion P and the folding portion F, and, if necessary, also on the side surface of the glass substrate. It is formed by etching the glass substrate 110 using the mask pattern layer as an etching mask.

The glass substrate 110 is etched by a physical or chemical etching method using the mask pattern layer as an etching mask, and in particular, a dry etching process such as plasma etching may be preferably performed.

Here, as shown in FIG. 1 , the mask pattern layer and the glass substrate 110 have a sufficiently different etch selectivity, so that the impact compensation pattern 121 is formed corresponding to the pattern of the mask pattern layer. A nanopattern 122 is formed on the glass substrate 110 .

That is, a pattern 121 for impact compensation is formed on the glass substrate 110 by a general dry or wet etching process, and the nanopattern ( 122) to form the composite pattern 120 on the glass substrate 110 .

If the mask pattern layer remains in the etching process for forming the nanopattern 122, the nanopattern 122 forming process is completed by removing the mask pattern layer, and the composite pattern (with the pattern 121 for impact compensation) ( 120) is achieved.

In addition, the size of the nanopattern 122 is preferably 30 to 1000nm in length and 30 to 1000nm in height of the horizontal cross section, and the nanopattern 122 is formed along the impact compensation pattern 121 . , depending on the shape (curved surface, rectangular trench shape, trapezoidal shape, etc.), etching depth or size (width) of the impact compensation pattern 121, the nanopattern 122 is only on the upper surface of the impact compensation pattern 121 It may be formed, or it may be formed along the top and side surfaces of the shock compensation pattern 121 , that is, along the surface of the shock compensation pattern 121 .

Here, in the case of using the block copolymer, since phase separation occurs in a state where polymers of the same type are agglomerated, the molecular weight of the polymer determines the size of the pattern. It is advantageous to form

And when a polymer mixture is used, the property of forming a heterogeneous mixture using a polymer having incompatibility is used. As the mixing ratio of the polymer constituting the mask pattern layer increases, the size of the nanopattern 122 increases. , it is advantageous to form the nanopattern 122 having a size of 100 nm or more.

That is, in the case of the block copolymer, it can be advantageously used to form the nanopatterns 122 of 100 nm or less, and in the case of the polymer mixture, it can be advantageously used to form the nanopatterns 122 of 100 nm or more.

Depending on the shape of the mask pattern layer, the horizontal cross section may be formed in various ways, such as a cylindrical shape, a prismatic shape, or a stripe shape. As described above, the control of the shape and size of the nanopattern 122 is controlled according to the polymer block constituting the heterogeneous polymer structure or the chemical properties of the polymer and the length (or molecular weight) of the block, and the composition ratio or mixing ratio, annealing temperature, etc. can be

In addition, the nanopatterns 122 according to the present invention may be formed to have the same size or different sizes regularly or irregularly, and the shape and regularity of these patterns may vary depending on the type of polymer and the phase separation in the process for phase separation as described above. It can be implemented by adjusting the conditions.

That is, in the case of the block copolymer, a relatively regular region pattern may be implemented, and in the case of the polymer mixture, a relatively irregular region pattern may be implemented. It can be implemented, and when the polymer mixture is used, a relatively irregular nanopattern 122 can be implemented.

In addition, by forming a separate guide pattern having a high etch selectivity on the glass substrate 110 , phase separation in a specific direction may be induced, and accordingly, the nanopattern 122 of a specific pattern may be induced.

Meanwhile, the impact compensation pattern 121 is formed to be larger than the scale of the nanopattern 122 , and is preferably formed to be less than half the thickness of the glass substrate 110 (thickness of the folding part or the flat part). it is preferable It may be formed to be 10 times larger than the size (width) of the nanopattern 122, and preferably, the width of the pattern for impact compensation is 10 to 300 μm, more preferably 100 to 120 μm. .

As described above, by forming the composite pattern 120 in which two types of patterns having different scales are superimposed on the glass substrate 110 as described above, it is possible to more effectively buffer and disperse the impact force such as a pen drop, thereby further improving the strength characteristics. It can be reinforced, and also the folding characteristics in the folding part can be further reinforced.

In this way, the glass substrate 110 on which the composite pattern 120 is formed may be reinforced in strength by performing a strengthening process as necessary.

If the etching selectivity between the mask pattern layer and the glass substrate 110 is not sufficiently different, as shown in FIG. 2 , a hard mask layer is formed on the glass substrate 110 on which the mask pattern layer is formed. Thereafter, the mask pattern layer may be removed to form a hard mask pattern layer including the hard mask layer, and the nanopattern 122 may be formed using the hard mask pattern layer as an etching mask.

That is, in order to sufficiently increase the etch selectivity with the glass substrate 110 , a hard mask pattern layer is formed on the glass substrate 110 . The hard mask pattern layer is formed of a material such as SiO ₂ and SiON having a high etch selectivity.

On the other hand, the nanopattern 122 may be formed on one or both sides of the glass substrate 110, that is, on the front side or on the back side, or on both the front and back sides, the polymer layer forming process, the phase separation induction process, The mask pattern layer forming process and the nanopattern 122 forming process may be implemented on the front or back side of the glass substrate 110 , or on the front and back sides of the glass substrate 110 .

If necessary, the nanopattern 122 may also be formed on the side surface of the glass substrate 110 according to the above process.

As described above, the nanopattern 122 is formed over the entire area of the glass substrate 110 on which the impact compensation pattern 121 is formed, or is formed only on the folding portion or on the folding portion and the flat portion when necessary. By implementing the composite pattern 120 on the glass substrate 110, the surface of the glass substrate 110 is improved, the impact force is dispersed to improve the impact resistance, and the flexible cover window 100 has further secured strength characteristics and folding characteristics. will provide

On the other hand, the folding part (F) according to the present invention may be formed to have a thinner thickness than the flat part (P) as described above, and while having such a shape, a glass having a pattern 121 for impact compensation is formed. The nanopattern 122 according to the present invention is formed on the folded portion or the entire region of the substrate 110 .

3 illustrates a process of forming the nanopattern 122 using the glass substrate 110 on which the pattern 121 for impact compensation is formed while having the slimmed flat portion P. Referring to FIG.

In the present invention, nanopatterns 122 are applied to one or both surfaces of the glass substrate 110 in order to improve impact resistance through improvement of pendrop characteristics in the folding part (F) and, at the same time, to improve folding characteristics and strength characteristics. By forming, the nanopatterns 122 are formed on the flat portion P to reinforce the overall pendrop characteristics of the glass substrate 110 as well as the folding portion F, which is vulnerable to the pendrop characteristics.

In addition, similarly to the pattern 121 for impact compensation, the pattern density of the nanopattern 122 formed on the folding part F is the same as the pattern density of the nanopattern 122 formed on the flat part P, or In particular, the pattern density of the nanopatterns 122 formed in the folding portion F in order to reinforce the pendrop characteristics in the thin folding portion F. The pattern of the nanopatterns 122 formed in the flat portion P. It can also be formed to be relatively denser than the density.

In addition, the height of the nanopattern 122 formed in the folding part is the same as the height of the nanopattern 122 formed in the flat part P, or the nanopattern 122 formed in the folding part F is particularly thin. ) may be formed to be lower than the height of the nanopattern 122 formed on the planar portion P.

This is to further enhance the effect of dispersing the impact force while further supplementing the folding characteristics of the relatively thin folding part (F).

Accordingly, the impact force transmitted from the front surface (touch surface) of the glass substrate 110 is transmitted to the inside of the glass substrate 110 so that the impact force can be dispersed or absorbed by the composite pattern 120 .

4 to 8 show the composite pattern 120 by forming the impact compensation pattern 121 on the glass substrate 110 on which the nanopattern 122 is formed in a manufacturing method according to another embodiment of the present invention. It is to provide a flexible cover window provided.

A method of manufacturing a flexible cover window according to another embodiment of the present invention includes a first step of providing a glass substrate 110 , and a second step of forming a polymer layer including a heterogeneous polymer structure on the glass substrate 110 . A third step of inducing phase separation between the heterogeneous polymer structures included in the polymer layer, and selectively removing any one polymer structure from among the phase-separated polymer layers to form a polymer structure remaining on the glass substrate 110 . A fourth step of forming a mask pattern layer made of After the nanopattern 122 is formed, a pattern 121 for impact compensation is formed on the glass substrate 110 , and a pattern 121 for impact compensation and the pattern 121 for impact compensation on the glass substrate 110 are formed. It is characterized in that the composite pattern 120 made of the nano-pattern 122 superimposed on the formed surface is formed.

The first to fifth steps are performed very similarly to the manufacturing method according to the first embodiment as described above. That is, in the embodiment according to the first manufacturing method, the nanopattern 122 is formed on the glass substrate on which the pattern 121 for impact compensation is formed, and in the embodiment according to the second manufacturing method, no pattern is formed on the surface of the glass. The nanopattern 122 is first formed on a substrate, a glass substrate on which a slimmed folding part is formed, or a glass substrate on which a predetermined pattern is formed on the slimmed folding part.

Since the formation process of the nanopattern 122 proceeds in the same manner as in the first to fifth steps, a detailed description thereof will be omitted.

As shown in FIG. 4 , in an embodiment for forming the pattern 121 for impact compensation on the glass substrate 110 on which the nanopattern 122 is formed, photoresist or DFR is applied on the glass substrate 110 . formed and patterned to form a resist pattern layer.

Using this as an etching mask, any one of wet etching, laser patterning, blasting, and roller stamping processes, or wet etching after laser patterning, wet etching after blasting, or wet etching after roller stamping 121) is formed.

Thereafter, by removing the remaining resist pattern layer, the flexible cover window in which the composite pattern 120 in which the pattern 121 for impact compensation and the nano-pattern 122 are compositely formed is provided.

* As described above, depending on the shape of the pattern for impact compensation (curved surface, rectangular trench shape, trapezoidal shape, etc.), the etching depth or size, the nano-pattern is formed only on the upper surface of the impact compensation pattern, or of the impact compensation pattern It may be formed along the upper surface and the side surface, that is, the surface of the impact compensation pattern.

As described above, by superimposing the nanopattern 122 on the glass substrate 110 on which the pattern 121 for impact compensation is formed to implement the composite pattern 120 , it is possible to improve scratches on the surface of the glass substrate 110 . . In particular, in general, the share of the occurrence of scratches of the thin glass substrate 110 is about 24%, but the share of occurrence of scratches is improved to the level of 0.4% by the pattern forming process according to the present invention, so that it is possible to provide a high-quality cover window 100 . there will be

7 illustrates a composite pattern 120 including a nanopattern 122 superimposed on an impact compensation pattern 121 on both sides of the glass substrate 110 according to an embodiment of the present invention.

On the other hand, the transparent resin layer 130 is further formed on one or both sides of the glass substrate 110 on which the composite pattern 120 according to the present invention is formed, so as to be bonded to the total surface of the display panel without empty space, and to improve bonding properties. characterized by improvement.

The transparent resin layer 130 is filled on the glass substrate 110 on which the composite pattern 120 is formed, to provide the cover window 100 with a uniform thickness as a whole, to absorb the impact force, and to be applied to the front surface of the display panel. When bonding, an empty space (air layer) is not present, so that visibility and bonding are improved.

The transparent resin layer 130 uses a transparent resin such as OCR (Optical Clear Resin) that is almost the same as the refractive index (1.5) of glass, for example, acrylic, epoxy, silicone, urethane, urethane compound, urethane acrylic compound, hybrid sol gel, A siloxane type, etc. can be used. According to the properties of the transparent resin layer 130, it may be mixed in various combinations to enhance strength and elasticity.

The transparent resin layer 130 may be formed of the same or different materials as a single layer or multiple layers according to product specifications, and may be formed on the front side and the back side of the glass substrate 110 or of the glass substrate 110 . It may be formed on the front side, the back side, and the front side (Total Surface). 8 shows that the composite pattern 120 is formed on the back side of the glass substrate 110 and the transparent resin layer 130 is formed on the upper layer, and FIG. It shows that the composite pattern 120 is formed on the back side of the substrate 110, and the transparent resin layer 130 is formed on the upper layer.

The transparent resin layer formed on the back side of the glass substrate 110 and the transparent resin layer formed on the front side of the glass substrate 110 are formed of the same material, or a transparent resin layer formed on the back side of the glass substrate 110 . It may be formed of a relatively softer material than the transparent resin layer formed on the front side of the glass substrate 110 .

This allows the durability to be maintained by forming a transparent resin layer with a relatively hard material on the part touched by the user.

In addition, according to the in-folding or out-folding method, the folded side is made of a harder material, and the stretched part is formed of a relatively soft material, so that cracks in the sagging part can be minimized. .

In another embodiment of the present invention, a buffer resin layer may be formed on the front side of the glass substrate on which the composite pattern is formed, and a cover glass substrate may be formed on the buffer resin layer. That is, a buffer resin layer is formed between the glass substrates, and a composite pattern is formed on the glass substrate on the back side.

Accordingly, when an impact is applied to the front side, the impact force is primarily absorbed by the buffer resin layer, and the impact force can be absorbed secondarily by the composite pattern.

In this case, the overall thickness of the cover glass substrate and the glass substrate may be made thinner, and the impact resistance to pendrops is improved, the folding characteristics and overall strength are increased.

The present invention in which the transparent resin layer is formed is implemented as a composite material of glass and a resin material, so that the flexibility, restoring force, elasticity and strength characteristics of the resin material are reinforced while maintaining the texture of the glass as much as possible.

In particular, in the present invention, by forming a composite pattern on the glass substrate and forming the transparent resin layer, the impact force on the pendrop is further dispersed or absorbed to further improve the impact resistance.

In addition, the occurrence of cracks in the folding part is minimized, and the shape of the composite pattern is prevented from being visually recognized from the outside, and flatness of a portion in contact with the display panel can be secured.

In addition, on the surface in contact with the display panel, the impact resistance is improved by reinforcing the elastic force on the cover window, and it functions to prevent scattering when the glass is broken.

In addition, a functional coating layer may be further formed on one or both surfaces of the cover window. The functional coating layer is formed of a transparent material like the above-described transparent resin layer, and by synthesizing resins having various properties, functionality is imparted.

The functional coating layer may be formed on the upper layer when the transparent resin layer is formed on the composite pattern. It can be formed by a known resin coating method such as spraying, dipping, or spin coating.

The functional coating layer may be formed as a single layer or multiple layers, the functional coating layer formed on the front surface of the cover window may be implemented as a strength reinforcing layer, and the functional coating layer formed on the back surface of the cover window may be implemented as an elastic reinforcing layer.

In the case of the hard coating on the front surface of the cover window, a resin having a relatively high hardness when cured, for example, a resin having a high content such as acrylic or epoxy, is used, and in the case of the soft coating on the rear surface of the cover window, hardening When used, the content of a relatively high elastic resin such as silicone or urethane synthetic resin is used. In addition, by controlling the content of organic and inorganic substances in the organic-inorganic hybrid sol-gel, it can be used by reinforcing strength or elasticity.

In addition, when the functional coating layer is formed in multiple layers, the functional coating layer formed on the front surface of the cover window is preferably formed of a relatively hard material toward the upper layer.

In addition, the functional coating layer, particularly the functional coating layer formed on the uppermost layer, may be given an AF (Anti Finger) or AR (Anti Reflective) function, and may be realized by synthesizing a resin having such a function, or various patterns may be applied to the functional coating layer, for example. It can also be implemented by forming a pattern like moth eye.

As described above, the cover window according to the present invention is basically a functional coating layer additionally formed to reinforce the strength and elasticity according to the use of a thin glass substrate, and the cover window can be protected even by an external impact or the pressure of the touch pen. let it be

In addition, the functional coating layer further prevents the occurrence of cracks in the folding area, and enhances the impact resistance by reinforcing the elastic force on the cover window on the surface in contact with the display panel, and functions to prevent scattering.

The following is a test of pendrop characteristics and folding characteristics of the flexible cover window according to an embodiment of the present invention.

For the pen drop test, a pen having a ball size of 0.5 mm and a weight of 6.2 g was used, and the height at which the cover window is broken by free-falling the pen from various heights on the front side of the glass substrate was measured, and the folding test was performed at two points. It is to measure the radius of curvature (2 Point Bending R) measured at the moment when it is bent and broken.

In one embodiment of the present invention, as shown in Figure 5, a composite pattern (size of the nanopattern ~50nm, the height of the nanopattern ~50nm, the size of the impact compensation pattern on the back side of the glass substrate (thickness 0.08mm) ~ 0.02mm, the height of the pattern for impact compensation ~0.02mm) is formed, and an acrylic transparent resin layer (thickness 0.01mm) is formed on the upper layer.

In the case of the glass substrate on which the composite pattern is formed according to an embodiment of the present invention, it was confirmed that the 2 Point Bending R value was 1.68 mm on average, indicating excellent folding characteristics.

And, in the pendrop test, it was confirmed that the glass substrate on which the composite pattern was formed was broken after the pendrop at an average height of 8 cm, showing excellent pendrop characteristics.

10 is an electron micrograph of a surface of a flexible cover window according to an embodiment of the present invention, and it was confirmed that a nanopattern was formed on the glass substrate.

As described above, the flexible cover window according to the present invention forms a composite pattern on a glass substrate to improve the surface scratch occupancy rate, and efficiently distributes the impact force to remarkably improve the impact resistance according to the improvement of the pendrop properties, while significantly improving the strength characteristics and It is possible to provide a flexible cover window with a secured folding characteristic.

100: cover window 110: glass substrate
120: composite pattern 121: shock compensation pattern
122: nano pattern 130: transparent resin layer
P: flat part F: folding part

Claims (16)

In the flexible cover window comprising: a flat portion formed corresponding to the flat area of the flexible display;
A composite pattern comprising a pattern for impact compensation and a nano-pattern formed by overlapping the pattern for impact compensation is formed on the glass substrate of the flexible cover window,
The shock compensation pattern is formed in the same size or different sizes regularly or irregularly,
The nano-pattern is overlapped with the pattern for impact compensation, and the flexible cover window with a composite pattern, characterized in that it is formed to have the same size or different sizes regularly or irregularly. According to claim 1, wherein the composite pattern,
The size of the nanopattern is 30-1000 nm in length and 30-1000 nm in height of the horizontal section,
The width of the pattern for impact compensation is a flexible cover window implemented with a composite pattern, characterized in that 10 times or more is greater than the width of the nanopattern. delete According to claim 1, The impact compensation pattern,
A flexible cover window with a composite pattern, which is formed on the folding part or the entire area of the flat part and the folding part, and is formed to be less than half the thickness of the glass substrate. According to claim 1, The impact compensation pattern,
A flexible cover window embodying a composite pattern, characterized in that it is formed on one or both surfaces of the glass substrate. The method according to claim 1, wherein the pattern density of the shock compensation pattern formed on the folding part is the same as that of the shock compensation pattern formed on the flat part, or
A flexible cover window embodying a composite pattern, characterized in that the pattern density of the shock compensation pattern formed in the folding part is relatively denser than the pattern density of the shock compensation pattern formed in the flat part. The method according to claim 1, wherein the height of the pattern for impact compensation formed on the folding part is equal to the height of the pattern for impact compensation formed on the flat part, or
A flexible cover window embodying a composite pattern, characterized in that the height of the pattern for the shock compensation pattern formed on the folding part is lower than the height of the pattern for the shock compensation pattern formed on the flat part. According to claim 1, The impact compensation pattern,
Any one of Wet Etching, Laser Patterning, Blasting, and Roller Stamping processes,
Or a flexible cover window embodying a composite pattern, characterized in that it is formed by any one of a wet etching process after laser patterning, a wet etching process after blasting, and a wet etching process after roller stamping. According to claim 1, wherein the nanopattern,
A flexible cover window with a composite pattern, which is formed on the folding part or the entire area of the flat part and the folding part, and implemented by a patterning process using a phase separation phenomenon between heterogeneous polymer structures. 10. The method of claim 9, wherein the heterogeneous polymer structure,
a block copolymer comprising a polymer A block and a polymer B block;
Or a flexible cover window with a composite pattern, characterized in that it is a polymer mixture comprising polymer A and polymer B. The method of claim 10, wherein the block copolymer,
A polymer A block derived from styrene or a derivative thereof and a polymer B block derived from an acrylic acid ester are combined;
or the polymer mixture,
A flexible cover window with a composite pattern comprising a polymer A derived from styrene or a derivative thereof and a polymer B derived from an acrylic acid ester. According to claim 1, wherein the nanopattern,
formed on one or both sides of the glass substrate,
A flexible cover window embodying a composite pattern, characterized in that it is formed on both sides and side surfaces of the glass substrate. The glass substrate of claim 1 , wherein the glass substrate on which the nanopatterns are formed comprises:
A flexible cover window with a composite pattern implemented, characterized in that it is reinforced. The method according to any one of claims 1 to 13, wherein the folding part,
A flexible cover window embodying a composite pattern, characterized in that it is formed thinner than the flat portion. 15. The flexible cover window of claim 14, wherein a transparent resin layer is further formed on one or both surfaces of the glass substrate on which the nano-pattern is formed. The method of claim 15, wherein the transparent resin layer,
A flexible cover window embodying a composite pattern, characterized in that it is formed of the same or different material as a single layer or multiple layers.

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