WO2018130289A1

WO2018130289A1 - Hardcoat layer system and method for manufacturing a hardcoat layer system in a continuous roll-to-roll process

Info

Publication number: WO2018130289A1
Application number: PCT/EP2017/050598
Authority: WO
Inventors: Neil Morrison; Jose Manuel Dieguez-Campo; Heike Landgraf; Stefan Hein; Tobias Stolley
Original assignee: Applied Materials, Inc.
Priority date: 2017-01-12
Filing date: 2017-01-12
Publication date: 2018-07-19
Also published as: CN110168135B; TWI674192B; CN110168135A; TW201945194A; TWI702140B; TW201838815A

Abstract

A hardcoat layer system (100) adapted for use in a touch screen panel is described. The hardcoat layer system (100) includes a flexible substrate (101) and a layer stack (110) provided on the flexible substrate (101). The layer stack (110) includes an adhesion promotion layer (111) provided on the flexible substrate (101) and an inorganic hardcoat top layer (113). The adhesion promotion layer (111) is configured to covalently bind to the surface of the flexible substrate, wherein a mechanical property of the adhesion promotion layer (111) at an interface (102) to the flexible substrate (101) is adapted to a mechanical property of the flexible substrate (101).

Description

HARDCOAT LAYER SYSTEM AND METHOD FOR

MANUFACTURING A HARDCOAT LAYER SYSTEM IN A CONTINUOUS ROLL-TO-ROLL PROCESS

TECHNICAL FIELD [0001] Embodiments of the present disclosure relate to hardcoat layer systems adapted for use in an electro-optical device and methods for manufacturing such hardcoat layer systems in a continuous roll-to-roll process. In particular, embodiments of the present disclosure relate to hardcoat layer systems including a stack of layers deposited on a flexible substrate. More specifically, embodiments of the present disclosure relate to hardcoat layer systems which are manufactured by a continuous roll-to-roll vacuum deposition process.

BACKGROUND

[0002] Processing of flexible substrates, such as plastic films or foils, is in high demand in the packaging industry, semiconductor industries and other industries. Processing may consist of coating a flexible substrate with a desired material, such as a metal, in particular aluminum, semiconductors and dielectric materials, etching and other processing steps conducted on a substrate for the desired applications. Systems performing this task typically include a process drum, e.g., a cylindrical roller, coupled to a processing system for transporting the substrate, and on which at least a portion of the substrate is processed. Accordingly, roll-to-roll (R2R) coating systems can provide a high throughput system.

[0003] Typically, a process, e.g. a physical vapor deposition (PVD) process, a chemical vapor deposition (CVD) process, and a plasma enhanced chemical vapor deposition (PECVD) process, can be utilized for depositing thin layers of metals which can be coated onto flexible substrates. In particular, roll-to-roll deposition systems are experiencing a strong increase in demand in the display industry and the photovoltaic (PV) industry.

[0004] Examples of products made of a coated flexible substrate are touch panels or organic light emitting diode (OLED) displays, which have received significant interest recently in display applications in view of their faster response times, larger viewing angles, higher contrast, lighter weight, lower power, and amenability to flexible substrates, as compared to liquid crystal displays (LCD).

[0005] Therefore, over the years, electro-optical devices, e.g. display devices or touch panels, have evolved into multiple layer systems in which different layers have different functions. However, the quality of conventional multilayer systems still need to be improved, for instance with respect to scratch resistance.

[0006] In light of the foregoing, there is a need to provide hardcoat layer systems adapted for use in electro-optical devices and methods for manufacturing such hardcoat layer systems that overcome at least some of the problems in the art.

SUMMARY

[0007] In light of the above, a hardcoat layer system and a method for manufacturing a hardcoat layer system according to the independent claims are provided. Further aspects, benefits, and features of the present disclosure are apparent from the claims, the description, and the accompanying drawings.

[0008] According to an aspect of the present disclosure, a hardcoat layer system adapted for use in a touch screen panel is provided. The hardcoat layer system includes a flexible substrate and a layer stack provided on the flexible substrate. The layer stack includes an adhesion promotion layer provided on the flexible substrate and an inorganic hardcoat top layer. The adhesion promotion layer is configured to covalently bind to the surface of the flexible substrate, wherein a mechanical property of the adhesion promotion layer at an interface to the flexible substrate is adapted to a mechanical property of the flexible substrate.

[0009] According to another aspect of the present disclosure, a hardcoat layer system adapted for use in a touch screen panel is provided. The hardcoat layer system includes a flexible substrate selected from the group consisting of: polycarbonate, polyethylene terephthalate, poly(methacrylic acid methyl ester), triacetyl cellulose, cyclo olefin polymer, poly(ethylene naphthalate). Further, the hardcoat layer system includes a layer stack provided on the flexible substrate, wherein the layer stack includes an adhesion promotion layer provided on the flexible substrate and an inorganic hardcoat top layer. The adhesion promotion layer is configured to covalently bind to the surface of the flexible substrate, wherein the hardness of the adhesion promotion is configured to gradually increase from the flexible substrate to the inorganic hardcoat top layer. The inorganic hardcoat top layer has a pencil hardness from 2H to 9H. The adhesion promotion layer and the inorganic hardcoat top layer are deposited by using a roll-to- roll PECVD process employing one and the same precursor.

[0010] According to yet another aspect of the present disclosure, an electro-optical device having a hardcoat layer system according to any embodiments described herein is provided. [0011] According to a further aspect of the present disclosure, a method for manufacturing a hardcoat layer system in a continuous roll-to-roll process is provided. The method includes providing a flexible substrate to at least one first processing zone and at least one second processing zone without braeking vacuum; depositing an adhesion promotion layer on the flexible substrate in the at least one first processing zone; and depositing an inorganic hardcoat top layer in the at least one second processing zone, wherein depositing the adhesion promotion layer includes forming covalent bonds between the flexible substrate and the adhesion promotion layer. Further, depositing the adhesion promotion layer includes adapting the mechanical properties of the adhesion promotion layer to the mechanical properties of the flexible substrate.

[0012] Embodiments are also directed at apparatuses for carrying out the disclosed methods and include apparatus parts for performing each described method aspect. These method aspects may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, embodiments according to the disclosure are also directed at methods for operating the described apparatus. The methods for operating the described apparatus include method aspects for carrying out every function of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:

FIGS. 1 and 2 show schematic views of a hardcoat layer system according to embodiments described herein;

FIG. 3 shows a schematic view of a hardcoat layer system according to further embodiments described herein;

FIGS. 4 to 6 show schematic views of a hardcoat layer system according to yet further embodiments described herein; FIG. 7 shows a schematic view of a processing system for manufacturing a hardcoat layer system according to embodiments described herein;

FIG. 8 shows a schematic view of an electro-optical device having a hardcoat layer system according to embodiments described herein; and

FIG. 9 shows a flow chart illustrating a method for manufacturing a hardcoat layer system in a continuous roll-to-roll process according to embodiments described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

[0014] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0015] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment can apply to a corresponding part or aspect in another embodiment as well. [0016] Before various embodiments of the present disclosure are described in more detail, some aspects with respect to some terms and expressions used herein are explained. [0017] In the present disclosure, a "hardcoat layer system" is to be understood as a stack of layers in which at least the uppermost layer includes a hardcoat layer. In particular, a "hardcoat layer system" can be understood as a stack of layers which includes an inorganic hardcoat top layer. More specifically, the hardcoat layer can be characterized in that the hardcoat layer has a pencil hardness of at least 2H. In this regard, it is to be understood that the resistance of a coating, i.e. the hardness of a coated layer, can be determined as the grade of the hardest pencil that does not permanently mark the coating when pressed firmly against the coated layer at a 45 degree angle. Typically, the pencil is pressed with a force of 7.5N at the surface to be tested. The pencil hardness test is also known as Wolff- Wilborn test.

[0018] In the present disclosure, a "layer stack" is to be understood as a stack of layers having at least two layers of different material composition. In particular, a stack of layers as described herein can be transparent. The term "transparent" as used herein can particularly include the capability of a structure to transmit light with relatively low scattering, so that, for example, light transmitted therethrough can be seen in a substantially clear manner. [0019] In the present disclosure, a "flexible substrate" may be characterized in that the substrate is bendable. For example, the flexible substrate may be a foil. In particular, it is to be understood that a flexible substrate as described herein can be processed in a continuous roll-to-roll process as described herein, for instance in a roll-to-roll processing system as described herein. In particular, the flexible substrate as described herein is suitable for manufacturing coatings or electronic devices on the flexible substrate. In particular, a flexible substrate as described herein can be transparent, e.g. the flexible substrate may be made of a transparent polymer material. More specifically, a flexible substrate as described herein may include materials such as polyethylene terephthalate (PET), polycarbonate (PC), polyethylene (PE), polyimide (PI), polyurethane (PU), poly(methacrylic acid methyl ester), triacetyl cellulose, cellulose triacetate (TAC), cyclo olefin polymer, poly(ethylene naphthalate), one or more metals, paper, combinations thereof, and already coated substrates like Hard Coated PET (HC-PET) or Hard Coated TAC (HC-TAC) and the like.

[0020] In the present disclosure, an "adhesion promotion layer" is to be understood as a layer which is provided between two structures, e.g. between a substrate and a layer or between two layers, and which is configured to promote adhesion between said two structures. For instance, the adhesion promotion layer APL can be configured to covalently bind to at least one of the two structures between which the adhesion promotion layer is provided. Accordingly, the adhesion promotion layer APL can be configured to covalently bind to the flexible substrate as described herein and/or to a subsequent layer deposited on the adhesion promotion layer APL. Further, the mechanical properties of the adhesion promotion layer can be adapted to the mechanical properties of the flexible substrate as described herein. For example, the flexibility, e.g. the E-modulus of the adhesion promotion layer APL can be adapted to the mechanical properties of the flexible substrate. Accordingly, the adhesion of the adhesion promotion layer APL to the substrate can be improved, since the adhesion promotion layer APL can follow a deformation of the flexible substrate.

[0021] In the present disclosure, a "hardcoat top layer" is to be understood as an uppermost layer of a stack of layers. In particular, the hardcoat top layer can be characterized in that the hardcoat top layer has a pencil hardness of at least 2H.

[0022] FIG. 1 shows a schematic view of a hardcoat layer system according to embodiments described herein. According to embodiments which can be combined with any other embodiments described herein, the hardcoat layer system is adapted for use in a touch screen panel. In particular, the hardcoat layer system includes a flexible substrate 101 and a layer stack 1 10 provided on the flexible substrate 101. For example, the flexible substrate 101 can include a polymer material selected from the group consisting of: polycarbonate, polyethylene terephthalate, poly(methacrylic acid methyl ester), triacetyl cellulose, cyclo olefin polymer, and poly(ethylene naphthalate). As exemplarily shown in FIG. 1 , the layer stack 1 10 includes an adhesion promotion layer 1 1 1 provided on the flexible substrate 101 and an inorganic hardcoat top layer 1 13. The adhesion promotion layer 1 1 1 is configured to covalently bind to the surface of the flexible substrate. Further, a mechanical property of the adhesion promotion layer 1 1 1 at an interface 102 to the flexible substrate 101 is adapted to a mechanical property of the flexible substrate 101. For example, the flexibility, e.g. the E-modulus, of the adhesion promotion layer APL can be adapted to the mechanical properties of the flexible substrate.

[0023] Accordingly, embodiments as described herein provide for an improved hardcoat layer system. In particular, the hardcoat layer system as described herein has an improved structural stability and integrity compared to conventional hardcoat layer systems. Thus, by employing embodiments of the hardcoat layer system as described herein in electro-optical devices, e.g. display devices or touch panels, the structural stability as well as the scratch resistance can be improved such that an improved product durability of the electro-optical devices can be achieved.

[0024] With exemplary reference to FIG. 2, according to embodiments which can be combined with any other embodiments described herein, the adhesion promotion layer 1 1 1 can have a thickness TA_PL of 100 nm < TA_PL≤ 800 nm.

[0025] For instance, the thickness T_APL of the adhesion promotion layer 1 1 1 can be selected from a range having a lower limit of 100 nm, particularly a lower limit of 200 nm, more particularly a lower limit of 300 nm and an upper limit of 600 nm, particularly an upper limit of 700 nm, more particularly an upper limit of 800 nm. Accordingly, by providing a hardcoat layer system with an adhesion promotion layer having a thickness TA_PL as described herein, the overall hardcoat layer system stability can be improved.

[0026] Further, with exemplary reference to FIG. 2, according to embodiments which can be combined with any other embodiments described herein, a thickness T_HTL of the inorganic hardcoat top layer 1 13 can be a 100 nm < T_HTL≤ 1 μηι. For instance, T_HTL of the inorganic hardcoat top layer can be selected from a range having a lower limit of 100 nm, particularly a lower limit of 200 nm, more particularly a lower limit of 300 nm and an upper limit of 600 nm, particularly an upper limit of 800 nm, more particularly an upper limit of 1 μιη. Accordingly, by providing a hardcoat layer system with an inorganic hardcoat top layer having a thickness T_HTL as described herein, the overall hardcoat layer system stability, particularly the scratch resistance, can be improved. [0027] According to embodiments which can be combined with any other embodiments described herein, the adhesion promotion layer 1 1 1 includes silicon oxycarbide SiOxCy. In particular, the adhesion promotion layer 1 1 1 can consist of silicon oxycarbide SiOxCy. Accordingly, by employing an adhesion promotion layer having a material composition as described herein, the adhesion promotion layer is configured to covalently bind to the surface of the flexible substrate as described herein, which is beneficial for improving the structural stability of the hardcoat layer system.

[0028] According to embodiments which can be combined with any other embodiments described herein, the inorganic hardcoat top layer 1 13 includes silicon oxide SiOx. In particular, the inorganic hardcoat top layer 1 13 can consist of silicon oxide SiOx. Alternatively, the inorganic hardcoat top layer 1 13 may include silicon carbide SiC, particularly the inorganic hardcoat top layer 1 13 can consist of silicon carbide SiC. [0029] According to embodiments which can be combined with any other embodiments described herein, the inorganic hardcoat top layer has a pencil hardness from 2H to 9H. For instance, the pencil hardness of the inorganic hardcoat top layer can be 2H, 3H, 4H, 5H, 6H, 7H, 8H or 9H. The pencil hardness of the inorganic hardcoat top layer can be measured by using the pencil hardness test which is also known as Wolff- Wilborn test. In particular, the hardness of the hardcoat top layer can be determined as the grade of the hardest pencil that does not permanently mark the hardcoat top layer when pressed firmly against the hardcoat top layer at a 45 degree angle. Typically, the pencil is pressed with a force of 7.5N at the surface to be tested, e.g. the surface of the hardcoat top layer.

[0030] With exemplary reference to FIGS. 4 and 5, according to embodiments which can be combined with any other embodiments described herein, the layer stack 110 can further include an antireflective layer stack 120 provided between the adhesion promotion layer 111 and the inorganic hardcoat top layer 113. For instance, the antireflective layer stack 120 can include a first layer 121 of SiOx provided on the adhesion promotion layer 111, a second layer 122 of NbOx provided on the first layer 121, and a third layer 123 of SiOx provided on the second layer 122, as exemplarily shown in FIG. 4. Further, the antireflective layer stack 120 may include a fourth layer 124 of ITO (inidium tin oxide) provided on the third layer 123, as exemplarily shown in FIG. 5.

[0031] For instance, the first layer 121 may have a thickness Ti of 5 nm < Ti < 10 nm. For instance, the thickness Ti of the first layer 121 can be selected from a range having a lower limit of 5 nm, particularly a lower limit of 6 nm, more particularly a lower limit of 7 nm and an upper limit of 8 nm, particularly an upper limit of 9 nm, more particularly an upper limit of 10 nm.

[0032] The second layer 122 may have a thickness T₂ of 5 nm < T₂ < 10 nm. For instance, the thickness T₂ of the second layer 122 can be selected from a range having a lower limit of 5 nm, particularly a lower limit of 6 nm, more particularly a lower limit of 7 nm and an upper limit of 8 nm, particularly an upper limit of 9 nm, more particularly an upper limit of 10 nm. [0033] The third layer 123 may have a thickness T₃ of 40 nm < T₂ < 80 nm. For instance, the thickness T₃ of the third layer 123 can be selected from a range having a lower limit of 40 nm, particularly a lower limit of 45 nm, more particularly a lower limit of 50 nm and an upper limit of 60 nm, particularly an upper limit of 70 nm, more particularly an upper limit of 80 nm.

[0034] The fourth layer 124 may have a thickness T₄ of 20 nm < T₃ < 60 nm. For instance, the thickness T₄ of the fourth layer 124 can be selected from a range having a lower limit of 20 nm, particularly a lower limit of 25 nm, more particularly a lower limit of 30 nm and an upper limit of 40 nm, particularly an upper limit of 50 nm, more particularly an upper limit of 60 nm.

[0035] Providing a hardcoat layer system with a layer stack 120 as described herein can be beneficial for enhancing the optical performance of the hardcoat layer system compared to conventional layer structures, particularly for use in electro-optical device such as OLED displays. For instance, the layer stack as described herein can be beneficial for obtaining a hardcoat layer system with antireflective properties.

[0036] With exemplary reference to FIG. 6, according to some embodiments which can be combined with other embodiments described herein, a further adhesion promotion layer 112 may be provided between the antireflective layer stack 120 and the inorganic hardcoat top layer 113. For instance, the thickness of the further adhesion promotion layer 112 can be selected from a range having a lower limit of 100 nm, particularly a lower limit of 200 nm, more particularly a lower limit of 300 nm and an upper limit of 600 nm, particularly an upper limit of 700 nm, more particularly an upper limit of 800 nm. Accordingly, by providing a hardcoat layer system with a further adhesion promotion layer having a thickness as described herein, the overall hardcoat layer system stability can be improved. [0037] Further, according to some embodiments which can be combined with other embodiments described herein, the further adhesion promotion layer 112 can be configured to covalently bind to the uppermost layer of the antireflective layer stack 120, e.g. to the third layer 123 or the fourth layer 124. Further, a mechanical property of the further adhesion promotion layer 112 may be adapted to a mechanical property of the uppermost layer of the antireflective layer stack 120, e.g. to the third layer 123 or the fourth layer 124. For example, the flexibility, e.g. the E-modulus, of the further adhesion promotion layer can be adapted to the mechanical properties of the uppermost layer of the antireflective layer stack 120. Accordingly, the structural stability and integrity of the hardcoat layer system as described herein can be improved even more compared to conventional hardcoat layer systems.

[0038] According to an example which can be combined with other embodiments described herein, the hardcoat layer system 100 adapted for use in a touch screen panel includes a flexible substrate 101 selected from the group consisting of: polycarbonate, polyethylene terephthalate, poly(methacrylic acid methyl ester), triacetyl cellulose, cyclo olefin polymer, poly(ethylene naphthalate). Further, the hardcoat layer system 100 includes a layer stack 110 provided on the flexible substrate 101, wherein the layer stack 110 includes an adhesion promotion layer 111 provided on the flexible substrate 101 and an inorganic hardcoat top layer 113. In particular, the adhesion promotion layer 111 is configured to covalently bind to the surface of the flexible substrate, wherein the hardness of the adhesion promotion can be configured to gradually increase from the flexible substrate to the inorganic hardcoat top layer 113. The inorganic hardcoat top layer 113 can have a pencil hardness from 2H to 9H. Typically, the adhesion promotion layer 111 and the inorganic hardcoat top layer 113 are deposited by using a roll-to-roll PECVD process employing one and the same precursor. [0039] Accordingly, in view of the embodiments of the hardcoat layer system as described herein, it is to be understood that the hardcoat layer system is well suited for being manufactured in a continuous roll-to-roll process, particularly a continuous vacuum deposition roll-to-roll process.

[0040] As an example, a schematic view of a processing system 300 for manufacturing a hardcoat layer system according to embodiments described herein is shown in FIG. 7. In particular, FIG. 7 shows a roll-to-roll processing system configured for carrying out a method for manufacturing a hardcoat layer system in a continuous roll-to-roll process according to embodiments described herein. [0041] As exemplarily shown in FIG. 7, the processing system 300 can include at least three chamber portions, such as a first chamber portion 302 A, a second chamber portion 302B and a third chamber portion 302C. At the third chamber portion 302C, one or more deposition sources 630 and optionally an etching station 430 can be provided as processing tools. A flexible substrate 101, e.g. a flexible substrate as described herein, is provided on a first roll 764, e.g. having a winding shaft. The flexible substrate is unwound from the first roll 764 as indicated by the substrate movement direction shown by arrow 108. A separation wall 701 is provided for separation of the first chamber portion 302 A and the second chamber portion 302B. The separation wall 701 can further be provided with gap sluices 740 to allow the flexible substrate 101 to pass therethrough. A vacuum flange 312 provided between the second chamber portion 302B and the third chamber portion 302C can be provided with openings to take up at least some processing tools. [0042] The flexible substrate 101 is moved through the deposition areas provided at a coating drum 710 and corresponding to positions of the deposition sources 630. During operation, the coating drum 710 rotates around an axis such that the flexible substrate 101 moves in the direction of arrow 108. According to some embodiments, the flexible substrate 101 is guided via one, two or more rollers from the first roll 764 to the coating drum 710 and from the coating drum 710 to the second roll 764', e.g. having a winding shaft, on which the flexible substrate 101 is wound after processing thereof. [0043] According to some embodiments, the deposition sources 630 can be configured for depositing the layers of the hardcoat layer system as described herein. As an example; at least one deposition source can be adapted for deposition of the adhesion promotion layer 111 and at least one deposition source can be adapted for deposition of the inorganic hardcoat top layer 113. Further, respective deposition sources which are adapted for deposition of the first layer 121, the second layer 122, the third layer 123, the fourth layer 124 and the further adhesion promotion layer 112 may be provided.

[0044] In some implementations, the first chamber portion 302A is separated in an interleaf chamber portion unit 302A1 and a substrate chamber portion unit 302A2. For instance, interleaf rolls 766/766' and interleaf rollers 305 can be provided as a modular element of the processing system 300. The processing system 300 can further include a pre-heating unit 394 to heat the flexible substrate. Further, additionally or alternatively a pre-treatment plasma source 392, e.g. an RF (radio frequency) plasma source can be provided to treat the substrate with a plasma prior to entering the third chamber portion 302C.

[0045] According to yet further embodiments, which can be combined with other embodiments described herein, optionally also an optical measurement unit 494 for evaluating the result of the substrate processing and/or one or more ionization units 492 for adapting the charge on the substrate can be provided.

[0046] According to some embodiments, the deposition material may be chosen according to the deposition process and the later application of the coated substrate. For instance, the deposition material of the deposition sources may be selected according to the respective material of the adhesion promotion layer 111, the inorganic hardcoat top layer 113, the first layer 121, the second layer 122, the third layer 123, the fourth layer 124 and the further adhesion promotion layer 112 as described herein. [0047] With exemplary reference to FIG. 8, according to one aspect of the present disclosure, an electro-optical device 150 having a hardcoat layer system 100 according to any embodiments described herein is provided. Accordingly, it is to be understood that hardcoat layer systems as described herein can beneficially be used in optical applications, for instance protection of OLEDs.

[0048] With exemplary reference to FIG. 9, embodiments of a method 200 for manufacturing a hardcoat layer system in a continuous roll-to-roll process is described. According to embodiments which can be combined with any other embodiments described herein, the method 200 includes providing (see block 210) a fiexible substrate to at least one first processing zone and at least one second processing zone without braeking vacuum. Further, the method includes depositing (see block 220) an adhesion promotion layer on the flexible substrate in the at least one first processing zone and depositing (see block 230) an inorganic hardcoat top layer in the at least one second processing zone.

[0049] In particular, depositing the adhesion promotion layer may include forming covalent bonds between the flexible substrate and the adhesion promotion layer. Further, depositing the adhesion promotion layer may include adapting the mechanical properties of the adhesion promotion layer to the mechanical properties of the flexible substrate. For example, the flexibility, e.g. the E-modulus of the adhesion promotion layer can be adapted to the mechanical properties of the flexible substrate.

[0050] According to embodiments of the method which can be combined with any other embodiments described herein, depositing the adhesion promotion layer and depositing the inorganic hardcoat top layer may include using a PECVD process and/or a HWCVD (Hot Wire Chemical Vapor Deposition) process. Further, depositing the antireflective layer stack 120 may also include using a PECVD process and/or a HWCVD process. For instance, the adhesion promotion layer and/or the inorganic hardcoat top layer and/or the antireflective layer stack layer stack 120 as described herein may be deposited using a low temperature microwave PECVD process.

[0051] According to further embodiments of the method which can be combined with any other embodiments described herein, depositing the adhesion promotion layer includes using at least one precursor selected from the group consisting of: HMDSO Hexamethyldisiloxane; ppHMDSO plasmapolymer Hexamethyldisiloxane; TOMCAT Tetramethyl Cyclotetrasiloxane (C₄H₁₆0₄Si₄); HMDSN Hexamethyldisilazane ([(CH₃)3Si]₂NH); and TEOS Tetraethyl Orthosilicate (Si(OC₂H₅)₄). [0052] Further, depositing the inorganic hardcoat top layer may also include using at least one precursor selected from the group consisting of: HMDSO; ppHMDSO; TOMCAT Tetramethyl Cyclotetrasiloxane (C₄H₁₆0₄Si₄); HMDSN Hexamethyldisilazane ([(CH₃)3Si]₂NH); and TEOS Tetraethyl Orthosilicate (Si(OC₂H₅)₄). In particular, depositing the adhesion promotion layer and depositing the inorganic hardcoat top layer may include using the same precursor.

[0053] In particular, depositing the adhesion promotion layer may further include using at least one agent selected from the group consisting of: peroxides as initiators, particularly TBPO (tert-butyl peroxide); acrylate monomers, particularly ethyl-hexyl acrylate; and a crosslinking agent, particularly BDDA (butanediol-diacrylate). Accordingly, by using at least one agent selected from the group as specified above, the adhesion capability of the adhesion promotion layer can be improved. Further, using at least one agent selected from said group can be beneficial for improving the structural stability of the hardcoat layer system as described herein.

[0054] In light of the foregoing, it is to be understood that embodiments described herein provide for an improved hardcoat layer system as well as for methods for manufacturing such an improved hardcoat layer system, particularly for use in electro-optical devices, e.g. touch panels.

[0055] While the foregoing is directed to embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. [0056] In particular, this written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the described subject-matter, including making and using any devices or systems and performing any incorporated methods. While various specific embodiments have been disclosed in the foregoing, mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope is defined by the claims, and other examples are intended to be within the scope of the claims if the claims have structural elements that do not differ from the literal language of the claims, or if the claims include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

A hardcoat layer system (100) adapted for use in a touch screen panel, comprising:

- a flexible substrate (101), and

- a layer stack (110) provided on the flexible substrate (101), wherein the layer stack (110) comprises an adhesion promotion layer (111) provided on the flexible substrate (101) and an inorganic hardcoat top layer (113), wherein the adhesion promotion layer (111) is configured to covalently bind to the surface of the flexible substrate, and wherein a mechanical property of the adhesion promotion layer (111) at an interface (102) to the flexible substrate (101) is adapted to a mechanical property of the flexible substrate (101).

The hardcoat layer system (100) according to claim 1, wherein the adhesion promotion layer (111) has a thickness TA_PL of 100 nm < TA_PL < 800 nm.

The hardcoat layer system (100) according to claim 1 or 2, wherein a thickness T_HTL of the inorganic hardcoat top layer (113) is 100 nm < T_HTL≤ 1 μ^ηι.

The hardcoat layer system (100) according to any of claims 1 to 3, wherein the adhesion promotion layer (111) includes silicon oxycarbide SiOxCy, particularly wherein the adhesion promotion layer (110) consists of silicon oxycarbide SiOxCy.

The hardcoat layer system (100) according to any of claims 1 to 4, wherein the inorganic hardcoat top layer (113) includes silicon oxide SiOx, particularly wherein the inorganic hardcoat top layer (113) consists of silicon oxide SiOx, or wherein the inorganic hardcoat top layer (113) includes silicon carbide SiC, particularly wherein the inorganic hardcoat top layer (113) consists of silicon carbide SiC.

The hardcoat layer system (100) according to any of claims 1 to 5, wherein the inorganic hardcoat top layer has a pencil hardness from 2H to 9H.

The hardcoat layer system (100) according to any of claims 1 to 6, wherein the layer stack (110) further comprises an antireflective layer stack (120) provided between the adhesion promotion layer (111) and the inorganic hardcoat top layer (113).

The hardcoat layer system (100) according to claim 7, wherein the antireflective layer stack (120) comprises a first layer (121) of SiOx provided on the adhesion promotion layer (111), a second layer (122) of NbOx provided on the first layer (121), and a third layer (123) of SiOx provided on the second layer (122).

The hardcoat layer system (100) according to claim 8, wherein the antireflective layer stack (120) further comprises a fourth layer (124) of ITO provided on the third layer (123).

The hardcoat layer system (100) according to any of claims 7 to 9, further comprising a further adhesion promotion layer (112) between the antireflective layer stack (120) and the inorganic hardcoat top layer (113).

A hardcoat layer system (100) adapted for use in a touch screen panel, comprising: - a flexible substrate (101) selected from the group consisting of: polycarbonate, polyethylene terephthalate, poly(methacrylic acid methyl ester), triacetyl cellulose, cyclo olefin polymer, poly(ethylene naphthalate), and

- a layer stack (110) provided on the flexible substrate (101), wherein the layer stack (110) comprises an adhesion promotion layer (111) provided on the flexible substrate (101) and an inorganic hardcoat top layer (113), wherein the adhesion promotion layer (111) is configured to covalently bind to the surface of the flexible substrate, wherein the hardness of the adhesion promotion is configured to gradually increase from the flexible substrate to the inorganic hardcoat top layer (113), wherein the inorganic hardcoat top layer (113) has a pencil hardness from 2H to 9H, and wherein the adhesion promotion layer (111) and the inorganic hardcoat top layer (113) are deposited by using a roll-to-roll PECVD process employing one and the same precursor.

An electro-optical device (150) having a hardcoat layer system (100) according to any of claims 1 to 11.

A method (200) for manufacturing a hardcoat layer system in a continuous roll-to-roll process, the method comprising

- providing (210) a flexible substrate to at least one first processing zone and at least one second processing zone without braeking vacuum;

- depositing (220) an adhesion promotion layer on the flexible substrate in the at least one first processing zone, and

- depositing (230) an inorganic hardcoat top layer in the at least one second processing zone, wherein depositing (220) the adhesion promotion layer includes forming covalent bonds between the flexible substrate and the adhesion promotion layer, and wherein depositing (220) the adhesion promotion layer includes adapting the mechanical properties of the adhesion promotion layer to the mechanical properties of the flexible substrate.

The method (200) for manufacturing a layer system according to claim 13, wherein depositing (220) the adhesion promotion layer and depositing (230) the inorganic hardcoat top layer comprises using a PECVD process and/or a HWCVD process.

The method (200) for manufacturing a barrier layer system according to claim 13 or claim 14, wherein depositing (220) the adhesion promotion layer includes using at least one precursor selected from the group consisting of: HMDSO; ppHMDSO; TOMCAT Tetramethyl Cyclotetrasiloxane (C₄Hi₆04Si₄); HMDSN Hexamethyldisilazane ([(CH₃)3Si]₂NH); and TEOS Tetraethyl Orthosilicate (Si(OC₂H₅)₄), and wherein depositing (220) the adhesion promotion layer further includes using at least one agent selected from the group consisting of: peroxides as initiators, particularly TBPO (tert-butyl peroxide); acrylate monomers, particularly ethyl-hexyl acrylate; and a crosslinking agent, particularly BDDA (butanediol-diacrylate).