CN116023697A

CN116023697A - Film having component gradient inorganic layer, method for manufacturing the same, and display device

Info

Publication number: CN116023697A
Application number: CN202211292239.1A
Authority: CN
Inventors: 李镕旭; 朴钟湖
Original assignee: SKC Hi Tech and Marketing Co Ltd
Current assignee: SK Microworks Solutions Co Ltd
Priority date: 2021-10-27
Filing date: 2022-10-20
Publication date: 2023-04-28
Also published as: JP2023065312A; KR20230060284A; JP7489164B2

Abstract

The film of the invention is prepared by adjusting the film to contain SiO _x C _y Is effective to provide SiO by varying the oxygen content ratio and the carbon content ratio in the thickness direction of the inorganic layer _x Film and SiC _y The advantage of the film is superior folding endurance compared to conventional films combining the two films together. Therefore, the film according to the above embodiment is suitable for use in a folding display device and the like requiring optical characteristics and scratch resistanceProtective films for a variety of products, both sexual and foldable.

Description

Film having component gradient inorganic layer, method for manufacturing the same, and display device

Technical Field

The invention relates to a film with a composition gradient inorganic layer, a preparation method thereof and a display device.

Background

With the demands of IT equipment development, display technologies are continuously developed, and technologies such as curved surface display and ventilation display have been in progress in commercialization. Recently, in the field of mobile devices that are required to realize both a large screen and portability, flexible display devices that can be flexibly bent or folded according to external force are preferred. Particularly, the foldable display device has the greatest advantages of being foldable and contractible when not in use, improving portability, and realizing a large screen when in use.

Transparent polyimide films or ultra-thin glass (UTG) are suitable for windows of flexible display devices, but still suffer from the problem that they are susceptible to external scratches, lack barrier properties to moisture or oxygen, and ultra-thin glass is less shatter resistant. Therefore, the window surface is now suitable for inorganic thin films having good scratch resistance and moisture permeability resistance, such as protective films of metal oxides or metal nitrides. In addition, in recent years, in order to prevent the visibility from being lowered by reflection of external light at the front surface of the display, a surface treatment technique for lowering the reflectance of a front surface film suitable for the display device has been developed.

For example, japanese laid-open patent publication No. 2003-098306 discloses a film whose surface is alternately stacked with silicon oxide layers and indium tin oxide layers so as to have an antireflection effect, while imparting scratch resistance thereto by depositing a dense carbon-based thin film on the surface thereof. However, there is a problem in that the film must be manufactured by separately depositing a carbon-based film to improve scratch resistance, which is excessively cumbersome and reduces transparency.

[ reference ]

(patent document 1) japanese laid-open patent publication No. 2003-098306.

Disclosure of Invention

Problems to be solved by the invention

SiOx films excellent in adhesion to a substrate and transparency, or SiC having high scratch resistance are being developed at present _y The film is suitable for the protective film of the window of the foldable display device, but SiO still exists _x Film lack scratch resistance and SiC _y The disadvantage of poor transparency of the film.

In order to solve the technical problem, attempts are being made to combine SiO _x Film and SiC _y Films or applications being adaptedSiO for regulating carbon-oxygen ratio _x C _y Film, however, as the number of films increases, the possibility of delamination during folding increases, and SiO is known to date _x C _y The film did not fully exert SiO _x Film and SiC _y The advantage of the film.

In order to solve the problem, the invention realizes that SiO can be effectively provided by adjusting different carbon-oxygen ratios in the thickness direction _x Film and SiC _y Film the film of the film advantage. In addition, by applying the roll-to-roll method to a deposition process such as reactive plasma sputtering, etc., to adjust different amounts of reactive gas injection at the front end and the rear end, the film can be effectively produced.

Accordingly, the present invention provides a film useful for protecting a window of a folding display device, a method of manufacturing the same, and a display device including the same, which have excellent optical properties, scratch resistance, and folding properties.

Means for solving the problems

According to one embodiment, the present invention provides a film comprising a base layer and a first inorganic layer disposed on one side surface of the base layer; wherein the first inorganic layer comprises silicon oxycarbide SiO _x C _y And the oxygen content ratio and the carbon content ratio are changed in the thickness direction.

According to another embodiment, the present invention provides a method for preparing a thin film comprising a step of depositing the first inorganic layer on one side surface of a base layer, wherein the first inorganic layer comprises silicon oxycarbide SiO _x C _y The method comprises the steps of carrying out a first treatment on the surface of the In the first inorganic layer, the oxygen content ratio and the carbon content ratio are caused to vary in the thickness direction.

According to another embodiment, the present disclosure provides a display device including the embodiment, comprising a display panel; a window provided at a front surface of the display panel; and a protective film provided on the surface of the window; wherein the protective film comprises the film of the embodiment.

Effects of the invention

The film according to the embodiment is prepared by forming a film containing the silicon oxycarbide SiO _x C _y In order to adjust the different oxygen content ratio and carbon content ratio, effectively provides SiO _x Film and SiC _y The advantage of the film is that the folding endurance is more excellent than a conventional film combining the two films together.

In particular by adding silicon oxycarbide SiO _x C _y The ratio of oxygen content to the bonding surface of the base layer in both sides of the inorganic layer and the ratio of carbon content in the other side are increased, thereby imparting scratch resistance to the surface while improving the bonding force and transparency to the base layer, and the inorganic layer can be realized as a single layer. In addition, the antireflection function can be provided by a laminated structure formed by combining the inorganic layer and other layers having different refractive indexes.

In particular, the thin film of the above embodiment can be effectively manufactured by adapting a roll-to-roll method to a deposition process such as reactive plasma sputtering, for example, to adjust different injection amounts of reactive gases at the front and rear ends.

Therefore, the film of the above embodiment can be suitably used for a protective film for protecting various products such as a folding display device, which are required to have optical characteristics, outdoor visibility, scratch resistance, and foldability.

Drawings

Figure 1 shows a cross-section of a film of an embodiment.

Figure 2 shows a film cross-section of another embodiment.

FIG. 3 shows a film preparation method according to an embodiment.

FIG. 4 shows another example of a film making process.

Figure 5 shows SIMS results for inorganic layer depths of films according to an embodiment.

Fig. 6 shows an example of a folding test of a film sample.

Fig. 7 shows an exploded perspective view of a display device of an embodiment.

Fig. 8a and 8b show a flexible display device of the outer fold and inner fold type, respectively.

Description of the reference numerals

1: display device, 1a: internal folding flexible display device, 1b: external folding flexible display device, 3: folding tester, 10: (protective) film, 10a: film sample, 20: window, 30: display panel, 100: a base layer, 201: particles with high oxygen ratio, 202: high carbon ratio particles, 210: first inorganic layer, 211: first side, 212: plane 2, 220: second inorganic layer 300: target, 310: first target, 320: second target, 330: third target, 340: fourth target, 350: fifth target, 401: first nozzle, 402: second nozzle, 501: discharge gas, 502: reaction gas, 600: plasma, 710: roller, 720: unwind roller, 730: winding roller, T: thickness of the first inorganic layer, p1, p2: folding points.

Detailed Description

Various embodiments will be described in detail below with reference to the accompanying drawings.

In describing the embodiments, if it is determined that a specific description of related known structures or functions may obscure the gist of the embodiments, a detailed description thereof will be omitted. In addition, the size of each structural element in the drawings may be exaggerated or omitted for illustrative purposes and may be different from the size of actual applications.

Herein, it is described that one structural element is formed above/below other structural elements or is connected or combined with each other, including being formed directly or indirectly through other structural elements, connected or combined. It should also be understood that the up/down reference of each structural element may vary depending on the direction in which the object is viewed.

The terminology used herein to refer to each structural element is used to distinguish it from other structural elements and is not intended to limit the embodiments. Furthermore, unless otherwise indicated, the singular forms "a", "an" and "the" mean plural referents unless the context clearly dictates otherwise

In this document, the terms first, second, etc. are used to describe various structural elements, and the above structural elements should not be limited by the above terms. The terms are used to distinguish one structural element from another.

The term "comprising" in this specification is intended to specify the presence of certain attributes, regions, steps, procedures, elements, and/or components, but does not preclude the presence or addition of other attributes, regions, steps, procedures, elements, and/or components, unless otherwise indicated.

Film with compositionally graded inorganic layer

FIG. 1 is a cross-section of a film employing an embodiment.

Referring to fig. 1, a film 10 according to an embodiment includes a substrate layer 100; and a first inorganic layer 210 disposed on one side surface of the base layer 100.

The film may comprise one or more of the first inorganic layers.

The first inorganic layer is formed on one side surface of the substrate layer and contains silicon oxycarbide SiO _x C _y 。

At the carbon oxide SiO _x C _y The silicon Si atoms may have a network structure of carbon C, oxygen O atoms bonded continuously. Thus, the first inorganic layer may have the properties of a glass material. Furthermore, the first inorganic layer may have a polycrystalline or amorphous structure.

The silicon oxycarbide SiO _x C _y The composition of (c) may be measured by a variety of methods, for example by secondary ion mass spectrometry SIMS. Wherein x and y are the relative atomic ratios of oxygen O and carbon C to silicon Si, respectively, and refer to the atomic number ratio or atomic mole ratio.

For example, silicon oxycarbide SiO _x C _y The atomic ratio x of oxygen to silicon may be 0 to 2, and the atomic ratio y of carbon to silicon may be 0 to 1. Furthermore, at the composition SiO of the first inorganic layer _x C _y In theory, there may be a relationship of x=2 (1-y), but there is no particular limitation thereto. I.e. the actual analysis result may differ from the theoretical value, e.g. x and y may differ from the theoretical value by within + -15%, specifically by within + -10%, more specifically by within + -5%.

Referring to fig. 1, the oxygen content ratio and the carbon content ratio of the first inorganic layer 210 are changed in the thickness T direction. The film according to the embodiment is prepared by forming a film containing the silicon oxycarbide SiO _x C _y Adjusting different oxygen in the thickness direction of the first inorganic layerContent ratio and carbon content ratio, effectively providing SiO _x Film and SiC _y The advantage of the film is that the folding endurance is more excellent than conventional films combining the two films together.

Referring to fig. 1, the first inorganic layer 210 has a first surface 211 facing the base layer 100, and a second surface 212 opposite to the first surface 211; according to one embodiment comprises silicon oxycarbide SiO _x C _y The oxygen-O content ratio may gradually decrease and the carbon-C content ratio may gradually increase as going from the first surface to the second surface in the first inorganic layer of (a).

Thus, the first surface may have a higher oxygen content than the second surface and a lower carbon content than the second surface, in particular, the first surface in the first inorganic layer may have the highest oxygen content and the lowest carbon content than the first surface, and thus the first surface may have a higher oxygen content than the second surface _x Similar properties. Furthermore, the second surface may have a higher carbon content than the first surface and a lower oxygen content than the first surface, in particular the second surface in the first inorganic layer has the highest carbon content and the lowest oxygen content, so the second surface may have a chemical composition with SiO _y Similar properties.

Silicon oxycarbide SiO on the first surface _x C _y The atomic ratio x of the medium oxygen to silicon may be, for example, 1.0 or more, 1.3 or more, 1.5 or more, or 1.6 or more, and may also be less than 2.0, 1.9 or less, 1.8 or less, or 1.7 or less. In addition, on the first surface, silicon oxycarbide SiO _x C _y The atomic ratio y of medium carbon to silicon may be, for example, 0 or more, more than 0,0.01, 0.1 or more, or 0.2 or more, and may also be 0.5 or less, 0.4 or less, or 0.3 or less.

And silicon oxycarbide SiO at the second surface _x C _y The atomic ratio x of the medium oxygen to silicon may be, for example, 0 or more, 0.01 or more, 0.05 or more, or 0.07 or more, and may also be 0.5 or less, 0.3 or less, 0.2 or less, or 0.1 or less. In addition, on the second surface, silicon oxycarbide SiO _x C _y The atomic ratio y of the medium carbon to the silicon can be, for example, 0.5 or more and 0.6 or moreAbove, 0.7 or more, or 0.8 or more, and may also be 1 or less, less than or equal to 1,0.95, or 0.9 or less.

For example, the first surface is silicon oxycarbide SiO _x C _y Wherein the atomic ratio x: y of oxygen O to carbon C can be 1.5-1.9:0.1-0.5, and the silicon oxycarbide SiO of the second surface _x C _y In the method, the atomic ratio x and y of oxygen O to carbon C can be 0.05-0.1:0.8-0.9. The atomic ratio refers to the number ratio of atoms and can be interpreted as meaning such as atomic molar ratio.

In particular, for example, the first surface is of silicon oxycarbide SiO _x C _y The atomic ratio of Si to O to C can be 1:1.5 to 1.9:0.1 to 0.5, and the silicon oxycarbide SiO of the second surface _x C _y The atomic ratio of Si to O to C can be 1:0.05 to 0.1:0.8 to 0.9.

Accordingly, since the oxygen content ratio of the first surface (the bonding surface with the base layer) of the thin film inorganic layer is high, the bonding force with the base layer can be improved to increase folding durability and transparency, and since the carbon content ratio of the second surface (the outer surface) is high, scratch resistance can be imparted to the surface, and both characteristics can be realized in a single layer, respectively.

Fig. 5 shows SIMS results for a first inorganic layer depth of a film according to an embodiment. As shown in fig. 5, the first inorganic layer in the film according to an embodiment has a composition gradient in which the ratio x of oxygen O and the ratio y of carbon C gradually increase or decrease in the thickness direction; specifically, as the first inorganic layer depth (x-axis value in fig. 5) increases, the amount of change in the molar content of oxygen (y-axis value of the dashed line curve in fig. 5) is approximately 2 times as large as the amount of change in the molar content of carbon (y-axis value of the solid line curve in fig. 5).

In the first inorganic layer of the film, there is a point where the increasing or decreasing change is intermediate (i.e., a point where the atomic ratio of oxygen to carbon (x/y) reaches about 2) (a point where two curves intersect is denoted by T1 in fig. 5), and the depth (percentage with respect to the thickness of the first inorganic layer) of the point can be defined as Txy in the following formula. The Txy defined by the following formula may be, for example, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, or 50% or more, and may also be 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or 50% or less. For example, txy, defined by the following formula, may be between 30% and 70%. Specifically, txy defined by the following formula may be 40% to 60%.

Txy(％)＝[(T0-T1)/T0]×100

Wherein T0 is the thickness of the first inorganic layer, and the unit is nm; t1 is the depth (nm) at which a spot having an atomic ratio x/y of oxygen to carbon of 2 is measured when the composition analysis is performed by SIMS in the thickness direction from the second surface to the first surface.

When Txy is within the desired range, the adhesion between the base layer and the first inorganic layer is controlled so as not to cause interlayer peeling, so that the folding property and the surface hardness are excellent, and the scratch resistance is improved, so that it can be more suitably used as a protective film for a foldable display device. Conversely, if Txy is out of the expected range, some components may be driven to one side surface, resulting in poor durability of the film.

Further, as shown in fig. 5, the carbon and oxygen contents may be increased or decreased in a certain ratio, respectively, according to the depth of the first inorganic layer.

For example, the carbon C content may be reduced in a certain proportion from the second surface (outer surface) to the first surface (bonding surface with the base layer). Specifically, when the composition analysis is performed by SIMS in the thickness direction from the second surface to the first surface of the first inorganic layer, the carbon content may be reduced by 4% to 8% as compared with the carbon content of the second surface every 10nm as the measurement depth increases.

As another example, the carbon oxygen O content may increase within a certain proportion from the second surface (outer surface) to the first surface (bonding surface with the base layer). Specifically, when the composition analysis is performed by SIMS in the thickness direction from the second surface to the first surface of the first inorganic layer, the oxygen content may be increased by 4% to 8% as compared with the oxygen content of the second surface every 10nm of the measurement depth.

The thickness of the first inorganic layer may be 5nm or more, 10nm or more, 20nm or more, 30nm or more, 50nm or more, or 100nm or more, or 1000nm or less, 500nm or less, 300nm or less, 200nm or less, or 150nm or less. For example, the thickness of the first inorganic layer may be 10nm to 500nm.

Second inorganic layer

Fig. 2 is a cross-section of a film according to another embodiment.

Referring to fig. 2, the film 10 according to another embodiment further includes the first inorganic layer 210 and the second inorganic layer 220, and the second inorganic layer 220 has a refractive index different from that of the first inorganic layer 210.

The refractive index of the second inorganic layer may be higher or lower than the refractive index of the first inorganic layer. Specifically, the refractive index of the second inorganic layer may be higher than the refractive index of the first inorganic layer.

The second inorganic layer may include one or more inorganic components, for example, may include one or more components selected from the group consisting of Li, al, K, ti, V, cr, mn, co, zn, sr, nb, mo, in, sn, sb and Cs.

The inorganic component may be contained in the inorganic layer in the form of an oxide combined with oxygen. For example, the second inorganic layer may contain an inorganic substance in which one or more components selected from the group consisting of Li, al, K, ti, V, cr, mn, co, zn, sr, nb, mo, in, sn, sb and Cs are combined with oxygen. Specifically, the second inorganic layer may contain an inorganic substance in which one or more components selected from the group consisting of Nb, ti, zn, si, in, sn and Cs, respectively, are combined with oxygen; more specifically, the second inorganic layer may comprise a material selected from niobium oxide (NbO ) ₂ 、Nb ₂ O ₅ ) Zinc oxide (ZnO), titanium oxide (TiO) ₂ ) And Indium Tin Oxide (ITO).

The thickness of the second inorganic layer may be 5nm or more, 10nm or more, 20nm or more, 30nm or more, 50nm or more, or 100nm or more, or 1000nm or less, 500nm or less, 300nm or less, 200nm or less, or 150nm or less. For example, the thickness of the second inorganic layer may be 10nm to 500nm.

The thin films according to the above embodiments respectively include one or more first inorganic layers and second inorganic layers, which may be alternately disposed with each other. Thus, an antireflection function can be imparted by a refractive index combination of these inorganic layers.

For example, the lamination configuration of the film is exemplified as follows:

a base layer/first inorganic layer/second inorganic layer;

a base layer/first inorganic layer/second inorganic layer/first inorganic layer;

a base layer/first inorganic layer/second inorganic layer/first inorganic layer; and

the base layer/first inorganic layer/second inorganic layer/first inorganic layer.

For example, the film reflectivity of the first inorganic layer and the second inorganic layer alternately arranged as described above may be 5% or less in all wavelength bands of visible light. Specifically, the film may have a reflectance of 4% or less, 3% or less, 2% or less, or 1% or less in all visible light bands.

The first inorganic layer and the second inorganic layer may be formed by depositing respective inorganic substances, and thus the first inorganic layer and the second inorganic layer may be inorganic deposition layers.

The number of inorganic layers in the film may be 1, 2 or more, 3 or more, or 5 or more, specifically 1 to 10, 2 to 8, or 4 to 6.

Substrate layer

The base layer serves to support the inorganic layer and serves as a substrate for depositing inorganic materials during the manufacturing process.

The substrate layer has flexibility to facilitate a continuous roll-to-roll process, and is not particularly limited in terms of materials. For example, the substrate layer may be a polymer film having flexibility.

The base layer may comprise a polymer resin. For example, the base layer may include one or more selected from the group consisting of polypropylene (PP), polyethylene (PE), polystyrene (PS), acrylate-butadiene-styrene copolymer (ABS), polycarbonate (PC), polyoxyethylene (POM), polyamide (PA), polypropylene glycoside (PPO), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), polystyrene Sulfonamide (PPs), polyimide (PI), polyamide-imide (PAI), and Polyvinylamine (PEI).

The substrate layer may be a transparent film. For example, the visible light transmittance of the base layer may be 85% or more, and particularly 95% or more.

The thickness of the base layer may be 10 μm to 500 μm, specifically 10 μm to 200 μm, 20 μm to 100 μm, or 30 μm to 80 μm.

In addition, the film may form an adhesive layer on the other surface of the base layer (i.e., on the other side where the first inorganic layer surface is formed). For example, the adhesive layer may comprise an optically clear adhesive.

Characteristics and uses of films

The film according to the above embodiment has high light transmittance and excellent scratch resistance, and thus is suitable for use as a window protective film for a display device.

The film according to the above embodiment may have a total light transmittance of 85% or more. For example, the light transmittance of the film may be 88% or more, or 90% or more, specifically, 85% to 99%,90% to 99%, or 95% to 99%, but is not limited thereto.

Further, the film may have a pencil hardness of 4H or more or 5H or more measured under a load of 500g and under a condition of 0.5mm/sec according to JIS-5400 standard. The pencil hardness measurement may be performed on the opposite surface of the base layer in the film, i.e., on the first inorganic layer (or the second inorganic layer).

In addition, the film according to the above embodiment has excellent adhesion between the base layer and the inorganic layer and folding durability, and thus can be applied as a protective film to a flexible display device, in particular, can be applied to a window of a foldable display device, and can maintain excellent performance even when repeatedly folded.

For example, after soaking the film in hot water at 100 ℃ for 30 minutes, the transverse cutting test according to the ISO 2409 standard may result in 100/90 or more (i.e., no flaking or peeling occurs in 90 or more of the 100 lattice units), and may specifically be 100/95 or more, or 100/97 or more.

In addition, the film was cut to a size of 2.54cm long by 15cm wide, and the folding test was repeated at a rate of 1 time per 2 seconds at room temperature to fold the substrate layer inward and to have a radius of curvature of 2R until interlayer peeling or cracking occurred, at which time the number of folds reached 40000 or more. For example, the number of folds may be 40000 times or more, 60000 times or more, or 80000 times or more. Fig. 6 is a folding test example of a film sample. Referring to fig. 6, the film sample 10a was fixed on the folding tester 3 while being repeatedly folded at a constant folding speed (times/second) and curvature R, it was possible to determine whether peeling or cracking occurred between the layers.

Method for producing film

The method for preparing the film according to one embodiment comprises the step of depositing the first inorganic layer on one side surface of the substrate layer, wherein the first inorganic layer comprises silicon oxycarbide SiO _x C _y 。

The deposition may be performed by physical deposition. In particular, the deposition may be performed by sputtering. More specifically, the deposition may be performed by reactive plasma sputtering (reactive plasma sputtering). The plasma may be an arc discharge plasma or a glow discharge plasma.

FIG. 3 is a method of preparing a film according to one embodiment.

Referring to fig. 3, the base layer 100 is mounted on an anode or a ground electrode, the target 300 is mounted on a cathode electrode, and then discharge output power is applied while discharge gas 501 is injected. Thereafter, the discharge gas 501 is in a state of plasma 600 separated into ions and electrons. Ions of the discharge gas collide with the target 300 and sputter off the target, and the detached target material reacts with the reaction gas to be deposited on the surface of the base layer in the form of oxide or deposited on the surface of the base layer without reaction. The cathode electrode may be supplied with an ac power source, in which case the target 300 may be divided into two parts (separated by a dotted line in the drawing) and mounted on the cathode electrode.

In sputtering, silicon carbide (SiC) may be used as a target, oxygen may be used as a reaction gas, and argon, helium, neon, or xenon may be used as a discharge gas. For example, the reaction gas may be injected in an amount of 5sccm to 20sccm, or in an amount of 10sccm to 15 sccm. The discharge gas may be injected at a flow rate of 200sccm to 1000 sccm.

According to an embodiment, in the first inorganic layer, the oxygen content ratio and the carbon content ratio are made to vary in the thickness direction.

The reactive plasma sputtering may adjust the amounts of the reactive gases injected at the first and second positions in the transport direction of the base layer to be different from each other while continuously transporting the base layer.

Referring to FIG. 3, a sputtering target 300 is shown to contain SiO _x C _y In the step of depositing the first inorganic layer 210 on the substrate layer 100, the discharge gas 501 that reacts with the target 300 and the first nozzle 401 and the second nozzle 402 that jet the reaction gas 502 are disposed on both sides of the deposition material 300 and are spaced apart from each other, and during the sputtering, the substrate layer 100 is conveyed so that the site to be deposited on the substrate layer 100 side sequentially passes through the position facing the first nozzle 401 and the position facing the second nozzle 402, and the flow rates of the reaction gas 502 that is jetted in the first nozzle 401 and the second nozzle 402 can be adjusted to be different from each other.

Thus, the particles deposited on the base layer 100 by the sputtering include the particles 201 of high oxygen ratio, which are formed of oxygen O as the reaction gas 502 ₂ React with SiC released by the target 300; and high carbon ratio particles 202 that do not react with the reactant gas. For example, the high oxygen ratio particles 201 and the high carbon ratio particles 202 may be deposited on one side of the substrate layer 100 at different ratios at a position facing the first nozzle 401 and a position facing the second nozzle 402.

Specifically, the substrate layer is sequentially transported in the order of the first location and the second location, and the amount of the reaction gas injected at the first location may be greater than the amount of the reaction gas injected at the second location.

As shown in fig. 3, the first nozzle 401 may spray the reaction gas 502 at a higher flow rate than the second nozzle 402. For example, the first nozzle may spray the reaction gas at a flow rate of 200sccm to 400sccm, and the second nozzle may spray the reaction gas at a flow rate of 0sccm to 100 sccm. In this case, the high oxygen ratio particles 201 may be deposited at a position facing the first nozzle 401, and in contrast, the high carbon ratio particles 202 may be deposited at a position facing the second nozzle 402.

Referring to fig. 3, for example, the first nozzle 401 may spray the reaction gas 502, and the second nozzle 402 may not spray the reaction gas, in which case the reaction gas 502 may be sprayed from the first nozzle 401 and spread to the surroundings. That is, the reaction gas 502 may exhibit the highest partial pressure at a position facing the first nozzle 401, and may exhibit a gradual decrease in partial pressure as it is farther from the position facing the first nozzle 401. Therefore, the reaction between SiC and the reaction gas 502 that are separated from the target 300 may be most active at a position facing the first nozzle 401, and the reaction between SiC and the reaction gas 502 that are separated from the target 300 may occur at a position facing the second nozzle 402 to the minimum.

Therefore, the deposition of the high oxygen ratio particles 201 generated by the reaction may be most active at the position facing the first nozzle 401, and the deposition of the unreacted high carbon ratio particles 202 may be most active at the position facing the second nozzle 402.

At this time, the underlayer 100 sequentially deposits at a position facing the first nozzle 401 and a position facing the second nozzle 402, so that the high oxygen ratio particles 201 are mainly deposited at the initial stage of deposition, and then the deposition ratio of the high carbon ratio particles 202 is gradually increased as the deposition ratio of the high oxygen ratio particles is gradually decreased.

Accordingly, the closer the deposited first inorganic layer 210 is to the base layer 100 in the thickness direction of the cross section, the higher the oxygen content ratio, and conversely, the farther from the base layer 100, the higher the carbon content ratio.

The first inorganic layer may be deposited on the base layer more than 2 layers, for which purpose more than 2 such depositions may be performed. For this purpose, sputtering may be performed by sequentially arranging 2 or more identical targets in the conveyance path of the underlayer.

According to another embodiment, the method of preparing a thin film may further include a step of depositing a second inorganic layer having a different refractive index from the first inorganic layer on one side of the base layer, and for this purpose, two targets may be sequentially arranged in a transport path of the base layer to perform sputtering.

One or more of the first inorganic layer and the second inorganic layer may be deposited separately, and for this purpose, a target may be prepared according to the kind and number of inorganic layers to be deposited. For example, the inorganic target used in the sputtering may be 1 or 2 or more, may be 1 or 2 or more in total, and may be specifically 1 to 10, 2 to 8, or 4 to 6 in total.

For example, the method of preparing a thin film may be to alternately deposit the first inorganic layer and the second inorganic layer with each other, and for this purpose, the two targets may be alternately placed on the transport path of the base layer.

Thus, the film may be prepared by a deposition method such as sputtering, and the transfer of the base layer may be performed by a roll-to-roll process. The inorganic multilayer film with continuity and uniform quality can be efficiently prepared through the roll-to-roll process.

FIG. 4 is an example of a thin film fabrication apparatus using a roll-to-roll process. Referring to fig. 4, the substrate layer 100 may be unwound from an unwinding roll 720 and fed in a specific direction by the rotation of a drum 710, and deposited inorganic substances are wound into a winding roll 730 by sputtering or the like.

As a specific example, an inorganic deposition apparatus using a roll-to-roll process may have 5 targets, namely, a first target (310), a second target (320), a third target (330), a fourth target (340), and a fifth target (350); siC may be used as the first, third, and

fifth targets

310, 330, and 350, and may be selected from niobium oxide (NbO ) ₂ 、Nb ₂ O ₅ ) Zinc oxide (ZnO), titanium oxide (TiO) ₂ ) And Indium Tin Oxide (ITO) are used as the second target 320 and the fourth target 340.

The thickness of the inorganic layer deposited from the targets by sputtering can be adjusted by varying the intensity of the power applied to the cathode electrode on which each target is mounted.

Display device

Fig. 7 is an exploded perspective view of a display device according to an embodiment. Referring to fig. 7, the display device 1 includes a display panel 30; a window 20 provided at a front surface of the display panel 30; and a protective film 10 provided on the surface of the window 20.

The display panel 30 may be a Liquid Crystal Display (LCD) panel. Alternatively, the display panel 30 may be an Organic Light Emitting Display (OLED) panel. The organic light emitting display device may include a front polarizing plate and an organic light emitting display panel. The front polarizing plate may be disposed at a front surface of the organic light emitting display panel. More specifically, the front polarizing plate may be adhered to a surface of the organic light emitting display panel on which an image is displayed. The organic light emitting display panel displays an image in pixel units by self-luminescence. The organic light emitting display panel includes an organic light emitting substrate and a driving substrate. The organic light emitting substrate includes a plurality of organic light emitting units respectively corresponding to pixels. The organic light emitting unit includes a cathode, an electron transport layer, a light emitting layer, a hole transport layer, and an anode, respectively. The driving substrate is drivingly coupled to the organic light emitting substrate. That is, the driving substrates may be coupled such that a driving signal, such as a driving current, may be applied to the organic light emitting substrate. More specifically, the driving substrate may apply a current to each of the organic light emitting cells to drive the organic light emitting substrate.

A film having a composition gradient inorganic layer according to an embodiment is used as the protective film 10 of the display device 1.

Namely, the display device according to an embodiment includes a display panel; a window provided at a front surface of the display panel; and a protective film provided on the surface of the window; wherein the protective film comprises a base layer; and a first inorganic layer disposed on one side surface of the base layer; the first inorganic layer contains silicon oxycarbide SiOxCy, and the oxygen content ratio and the carbon content ratio vary in the thickness direction.

The display device according to one embodiment may have flexibility. For example, the display device according to an embodiment may be a flexible display device, or may be specifically a foldable display device. More specifically, the foldable display device may be either inner-folding or outer-folding depending on its folding direction.

Fig. 8a and 8b are respectively an external folding and an internal folding type flexible display device. Referring to fig. 8b, the display device may be an in-folding flexible display device 1a in which a screen is located at an inner side of a folding direction thereof. Alternatively, referring to fig. 8a, the display device may be an external folding flexible display device 1b in which the screen is located at the outer side of the folding direction thereof. Referring to fig. 8b, in case of the inner fold type 1a, a load is applied to the inwardly folded point p1, and referring to fig. 8a, in case of the outer fold type 1b, a load is applied to the outwardly folded point p 2. In this case, if the protective film 10 does not have sufficient interlayer adhesion or flexibility, the load upon folding will cause interlayer peeling or cracking to deteriorate the characteristics.

However, since the display device according to the above-described embodiment uses a film having a composition gradient inorganic layer as a protective film, cracking or interlayer peeling does not occur even when repeatedly folded, and has high light transmittance and excellent scratch resistance, a window can be protected. In addition, the protective film has an anti-reflection function, so that the visibility of the device can be improved when used outdoors.

Description of the embodiments

The following examples are merely to aid in understanding, and the scope of the achievable is not limited thereto.

Comparative example 1A preparation of a substrate/SiC _y Film of layer composition

A reactive plasma sputtering apparatus using a roll-to-roll method as shown in fig. 3 was prepared. Referring to fig. 3, siC is used as a target 300 and mounted, andargon Ar gas as discharge gas and oxygen O ₂ Is injected as a discharge gas. A polyethylene terephthalate film (PET, U483, toray) having a thickness of 50 μm as the base layer 100 was conveyed in a roll-to-roll manner, sequentially passing through the front faces of the first nozzle 401 and the second nozzle 402.

When the vacuum degree reaches 5X 10 ^-6 At torr, sputtering was performed by pumping under high vacuum for 3 hours, as shown in Table 1 below, with argon being injected at the same flow rate of 300sccm at the first nozzle and the second nozzle, without injecting oxygen. As a result, silicon carbide SiC having a thickness of about 150nm was deposited on the base layer _y A thin film of layers.

Comparative example 1B preparation of substrate/SiC _x Film of layer composition

The same procedure as in comparative example 1A was repeated, but Si was used as a target and was mounted, and oxygen was injected at the same flow rate at each of the first nozzle and the second nozzle to sputter as shown in table 1 below. As a result, a silicon oxide SiO having a thickness of about 150nm was deposited on the base layer _x A thin film of layers.

Comparative example 1C preparation of a substrate/SiO _x C _y Film of layer composition

The same procedure as in comparative example 1A above was repeated, but as shown in table 1 below, sputtering was performed by injecting oxygen gas at the same flow rate of 25sccm at both the first nozzle and the second nozzle. As a result, a silicon oxycarbide SiO layer having a thickness of about 150nm was deposited on the base layer _x C _y A thin film of layers.

Example 1 preparation of a substrate/SiO _x C _y Film consisting of (component gradient) layers

The same procedure as in comparative example 1A above was repeated, and as shown in table 1 below, argon gas was injected at the same flow rate at 300sccm at the first nozzle and the second nozzle, and oxygen gas was injected at a flow rate of 100sccm only at the first nozzle, and sputtering was performed at the second nozzle without injection. As a result, silicon oxycarbide (SiO) having a thickness of about 150nm and a composition gradient in the thickness direction was deposited on the base layer _x C _y ) Is a film of (a).

[ Table 1 ]

Comparative example 2 preparation of a substrate/SiO ₂ /Nb ₂ O ₅ /SiO ₂ /Nb ₂ O ₅ /SiO ₂ Film of layer composition

A reactive plasma sputtering apparatus using a roll-to-roll method as shown in fig. 4 was prepared. Referring to fig. 4, si as a first target 310, nb as a second target 320, si as a third target 330, nb as a fourth target 340, and Si as a fifth target 350 are respectively installed around a drum 710 and sequentially disposed. The 5 targets are provided with a first nozzle and a second nozzle, respectively, as shown in FIG. 3, so as to spray the discharge gas Ar and the reaction gas O ₂ . A polyethylene terephthalate film (PET, U483, toray) having a thickness of 50 μm as a base layer was fed by a roll-to-roll method so as to pass sequentially in front of the first target, the second target, the third target, the fourth target, and the fifth target. After 3 hours of high vacuum pumping, when the vacuum reaches 5×10 ^- ⁶ At torr, the first nozzle and the second nozzle of each target material spray discharge gas Ar at a flow rate of 300sccm, and spray reaction gas O at a flow rate of 50sccm ₂ The power intensity was adjusted as shown in table 2 below to adjust the thickness of the deposited inorganic layer. As a result, silicon oxide SiO was alternately laminated on the base layer ₂ Layer and niobium oxide Nb ₂ O ₅ A laminated film of five layers in total.

EXAMPLE 2 preparation of the substrate/SiO _x C _y (component gradient)/Nb ₂ O ₅ /SiO _x C _y (component gradient)/Nb ₂ O ₅ /SiO _x C _y Preparation of a film consisting of a (component gradient) layer

The same procedure as in comparative example 2 above was repeated, substituting the first, third and fifth targets with SiC, e.gAs shown in the foregoing example 1, the reaction gas O was injected at the first nozzle alone in these targets ₂ The second nozzle does not spray the reaction gas O ₂ . In addition, the intensity of power applied to each target was adjusted as shown in table 2 below to adjust the thickness of the inorganic layer deposited thereby.

As a result, a silicon oxycarbide SiO having a composition gradient in the thickness direction on the base layer was obtained _x C _y Layer and niobium oxide Nb ₂ O ₅ A laminated film of five layers in which layers are alternately laminated.

[ Table 2 ]

Test example 1: measuring the composition gradient of an inorganic layer

To confirm the composition gradient, the composition in the depth direction of the inorganic layer of the film sample was measured by SIMS (secondary ion mass spectrometry), and the ratio of oxygen O and carbon C components was found. Specifically, based on SIMS measurements corresponding to silicon Si, oxygen O, and carbon C, stoichiometric atomic ratios of oxygen O and carbon C relative to silicon (Si) were calculated from the depth of the inorganic layer, the results of which are shown in fig. 5 below.

Test example 2: total light transmittance

The total light transmittance of the film samples was measured using a transmission haze meter. The results are shown in tables 3 and 4 below.

Test example 3: hardness of pencil

The pencil hardness was measured on the inorganic layer surface of the film sample under conditions of 500g load and 0.5mm/sec according to JIS-5400 standard. The results are shown in tables 3 and 4 below.

Test example 4: transverse cutting test

After immersing the film sample in hot water at 100 ℃ for 30 minutes, a cross-cut test was performed on the surface of the inorganic layer according to ISO 2409 standard. The results are shown in Table 3 below.

Test example 5: folding test

The film sample was cut to a length of 15cm and a width of 2.54cm and mounted on a folding tester to confirm whether interlayer peeling occurred during repeated folding. The fold test causes the substrate layer to fold inwardly and to have a radius of curvature of 2R and the fold test is repeated up to 80000 times at a rate of 1 time per 2 seconds. As a result, if no interlayer peeling and cracking were observed in the film after repeated folding, it was determined as OK, and if interlayer peeling or cracking was observed, it was determined as NG. The results are shown in tables 3 and 4 below.

[ Table 3 ]

As shown in table 3 above, the film with a composition gradient according to example 1 has higher light transmittance while also having excellent scratch resistance, interlayer adhesion, and folding durability. In contrast, the films of comparative examples 1A to 1C having no component gradient were inferior in evaluation result of at least one of the above-described properties.

[ Table 4 ]

As shown in table 4 above, the film of example 2 having a composition gradient has an excellent antireflection function while having excellent scratch resistance and folding durability as compared with the film of comparative example 2 having no composition gradient.

Claims

1. A film, comprising:

a base layer, and

a first inorganic layer disposed on one side surface of the base layer;

the first inorganic layer comprises silicon oxycarbide SiO _x C _y And the oxygen content ratio and the carbon content ratio are changed in the thickness direction.

2. The film of claim 1,

the first inorganic layer has a first surface facing the base layer, and

a second surface opposite the first surface;

the carbon content ratio gradually increases as the oxygen content ratio gradually decreases from the first surface to the second surface.

3. The film of claim 2, wherein the atomic ratio of oxygen O to carbon C in the first surface is 1.5 to 1.9:0.1 to 0.5 and the atomic ratio of oxygen O to carbon C in the second surface is 0.05 to 0.1:0.8 to 0.9.

4. The film of claim 2, wherein the film has a Txy defined by the formula:

Txy(％)＝[(T0-T1)/T0]×100

wherein T0 is the thickness of the first inorganic layer, and the unit is nm;

t1 is the depth (nm) at which a spot having an atomic ratio x/y of oxygen to carbon of 2 is measured when the composition analysis is performed by SIMS in the thickness direction from the second surface to the first surface.

5. The film according to claim 2, wherein the carbon content is reduced by 4% to 8% as compared with the carbon content of the second surface every 10nm as measured in the thickness direction from the second surface to the first surface of the first inorganic layer by SIMS.

6. The film of claim 1,

cutting the film into a size of 15cm long and 2.54cm wide, and repeating a folding test at a speed of 1 time every 2 seconds under normal temperature conditions to enable the substrate layer to be folded inwards and enable the curvature radius to be 2R until interlayer peeling or cracking occurs, wherein the folding time is up to above 40000 times, and the total light transmittance is above 85%;

the pencil hardness measured under the conditions of 500g load and 0.5mm/sec according to JIS-5400 standard is 4H or more;

after soaking in hot water at 100 ℃ for 30 minutes, the transverse cutting test result according to the ISO 2409 standard is more than 100/95.

7. The film of claim 1,

the film further comprises a second inorganic layer having a refractive index different from that of the first inorganic layer;

the second inorganic layer contains an inorganic substance in which one or more components selected from the group consisting of Li, al, K, ti, V, cr, mn, co, zn, sr, nb, mo, in, sn, sb and Cs are combined with oxygen;

the thickness of each of the first inorganic layer and the second inorganic layer is 10 nm-500 nm;

the first inorganic layers and the second inorganic layers are alternately arranged;

wherein the film has a reflectance of 5% or less.

8. A method for preparing a thin film comprises the step of depositing a first inorganic layer on one side surface of a substrate layer, wherein the first inorganic layer comprises silicon oxycarbide SiO _x C _y ；

In the first inorganic layer, the oxygen content ratio and the carbon content ratio are caused to vary in the thickness direction.

9. The method for producing a film according to claim 8, wherein,

the deposition is performed by reactive plasma sputtering;

taking silicon carbide SiC as a target material;

the reaction gas uses oxygen, and the discharge gas uses argon, helium, neon or xenon;

the reactive plasma sputtering is configured to continuously transport the underlayer, and the amounts of the reactive gases injected at the first position and the second position in the transport direction of the underlayer are adjusted to be different from each other.

10. A display device, comprising:

a display panel;

a window provided at a front surface of the display panel; and

a protective film provided on the surface of the window;

wherein the protective film comprises:

a base layer; and

a first inorganic layer provided on a surface of one side of the base layer;