Optical laminate and method for manufacturing optical laminate

Abstract

This invention provides an optical laminate and its manufacturing method that prevent abnormal discharge of the marking layer on defective areas of a display and enable marking of defective areas with fewer steps and lower cost. The optical laminate of this invention is characterized by being formed by laminating a substrate and an optical functional layer, wherein the optical functional layer comprises an inorganic oxide or an inorganic nitride, and a marking layer is locally formed on the surface of the optical functional layer. The marking layer comprises a semiconductor material and has a reflectivity of 40% or more for light in the wavelength range of 400 nm to 700 nm.

Description

Technical Field

[0001] The present invention relates to an optical laminate having an identification layer that displays the location of defects generated in an optical functional layer, and a method thereof. This application claims priority based on Japan Patent Application No. 2021-121879, filed on July 26, 2021, the contents of which are incorporated herein by reference. Prior Technology

[0002] For example, in flat panel displays (FPDs), touch panels, solar cells, etc., various optical laminates (anti-reflective films) are used to prevent surface reflection of incident external light and improve visibility.

[0003] Previously, as an antireflective film, a multilayer film (optical functional layer) comprising a high-refractive-index layer and a low-refractive-index layer sequentially deposited on a transparent substrate was proposed. In the manufacture of this type of antireflective film, an optical functional layer comprising a high-refractive-index film or a low-refractive-index film is generally formed on one side of the transparent substrate by, for example, depositing a metal oxide film or a metal nitride film using sputtering or the like. Subsequently, surface treatments such as forming an antifouling layer are performed as needed.

[0004] During the manufacture of this type of antireflective film, defects sometimes occur in the optical functional layer. These defects can be detected by optical inspection devices. Furthermore, there is a known method in which, when a defect is detected in the optical functional layer, the location of the defect is marked so that it can be easily identified in subsequent steps (e.g., Patent Documents 1-3).

[0005] For example, Patent Document 1 discloses a marking method in which a marking is formed at the defect site by applying pressure to the film surface containing the detected defect area using an embossing roller to perform embossing processing.

[0006] Furthermore, Patent Document 2 discloses a method for manufacturing a double-sided film, which involves forming a recess or through hole in the area containing the detected defect, applying ink, etc., to form a mark on the defect site.

[0007] Furthermore, Patent Document 3 discloses a defect marking method, which involves writing marks on defective areas of an optical film using a marking pen.

[0008] However, the methods disclosed in these patent documents 1-3 require the separate installation of a transfer device for forming embossing or an ink jetting device, which would complicate the process and increase manufacturing costs. Furthermore, there are concerns that physical pressure, such as embossing, could lead to further defects.

[0009] Therefore, for example, it is also considered to use a sputtering device to form a sputtered film on the defect site during the formation of the optical functional layer, thereby marking the defect site. In this method, since the marking of the defect site is also formed by sputtering in the same way as the formation of the optical functional layer, it has the advantage of being able to achieve continuous steps. Previous technical documents Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2017-137527 Patent Document 2: Japanese Patent Application Publication No. 2019-173061 Patent Document 3: Japanese Patent Application Publication No. 2014-016217 Summary of the Invention

[0011] [The problem the invention aims to solve]

[0012] As mentioned above, when marking defect locations using sputtering, it is considered to use a metal material with high reflectivity to improve visibility. However, since the defect marking layer formed using a metal material is a conductive metal sputtered film, there are concerns when performing corona treatment or other subsequent steps, namely, that abnormal discharge may be induced in the marking layer, thereby damaging the optical functional layer.

[0013] The present invention was made in consideration of this situation, and its purpose is to provide an optical laminate and a method thereof for manufacturing the same, which prevents abnormal discharge of the marking layer on the display defect area and enables the marking of the defect area in fewer steps and at low cost. [Technical means to solve the problem]

[0014] In other words, to solve the above problems, the present invention proposes the following solution. The optical stack of the present invention is characterized in that it is formed by stacking a substrate and an optical functional layer, wherein the optical functional layer comprises an inorganic oxide or an inorganic nitride, and a marking layer is locally formed on the surface of the optical functional layer, wherein the marking layer comprises a semiconductor material and has a reflectivity of 40% or more for light in the wavelength range of 400 nm to 700 nm.

[0015] According to the present invention, the marking layer formed on the defect site of the optical functional layer is formed by a semiconductor material with a reflectivity of 40% or more for light in the range of wavelengths from 400 nm to 700 nm. Therefore, the defect site can be easily detected under visible light in subsequent steps, and when the optical stack 10 is subjected to corona treatment or the like in subsequent steps, abnormal discharge toward the marking layer can be effectively suppressed.

[0016] Furthermore, in this invention, the aforementioned marking layer may contain germanium or silicon.

[0017] According to the present invention, the above-mentioned marking layer may be formed by overlapping at least a portion of the defective portion of the above-mentioned optical functional layer.

[0018] According to the present invention, the above-mentioned marking layer may be a sputtered film formed by sputtering.

[0019] According to the present invention, the above-mentioned optical laminate is an anti-reflective film, and the above-mentioned optical functional layer may include a laminate formed by alternately laminating low refractive index layers and high refractive index layers.

[0020] The method for manufacturing an optical laminate of the present invention is characterized in that it is a method for manufacturing an optical laminate as described in the above-mentioned items, comprising: an optical functional layer forming step, which forms the optical functional layer on the substrate; a defect inspection step, which inspects for defects in the optical functional layer; and a defect area display step, which forms the marking layer in the area containing the defect when a defect is detected in the defect inspection step. [Effects of the Invention]

[0021] According to the present invention, an optical laminate and its manufacturing method are provided that prevent abnormal discharge of the marking layer on the display defect area and enable the marking of the defect area in fewer steps and at low cost. Simple Explanation of the Diagram

[0022] Figure 1 is a top view of an optical laminate according to one embodiment of the present invention. Figure 2 is a cross-sectional view of the optical laminate in Figure 1. Figure 3 is a schematic diagram of an optical laminate manufacturing apparatus used in a method for manufacturing optical laminates. Figure 4 is a graph showing the results of the embodiment. Implementation

[0023] Hereinafter, with reference to the drawings, an optical laminate according to one embodiment of the present invention and its manufacturing method will be described. Furthermore, the embodiments shown below are specifically described to better understand the spirit of the invention, and unless otherwise specified, they are not intended to limit the invention. Also, to facilitate understanding of the features of the present invention, for convenience, some parts of the key components are sometimes shown in enlarged form in the drawings used in the following description, and the dimensional ratios of the constituent elements are not limited to the actual situation.

[0024] (Optical laminate) As one embodiment of the present invention, an anti-reflective film is illustrated. Figure 1 is a top view of an optical laminate according to one embodiment of the present invention. Figure 2 is a cross-sectional view of the optical laminate of Figure 1. The optical laminate (anti-reflective film) 10 of this embodiment has a transparent substrate (substrate) 11 and an optical functional layer 12 formed on one side of the transparent substrate 11. Furthermore, an identification layer 13 is formed in such a way that it overlaps with the defective portion D of the optical functional layer 12.

[0025] The transparent substrate 11 can be formed of any transparent material that can transmit light in the visible light region; for example, a plastic film is preferable. Specific examples of materials constituting the plastic film include polyester resins, acetate resins, polyether resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, and polyphenylene sulfide resins.

[0026] Within the limit of not significantly impairing optical properties, the transparent substrate 11 may also include reinforcing materials, such as cellulose nanofibers and nano-silica. Polyester resins, acetate resins, polycarbonate resins, and polyolefin resins are particularly preferred. Specifically, triacetyl cellulose (TAC) substrate is preferred. Alternatively, glass film can be used as an inorganic substrate.

[0027] The transparent substrate 11 can also be a film endowed with optical or physical functions. Examples of substrates with optical or physical functions include polarizing plates, phase difference compensation films, hot wire blocking films, transparent conductive films, brightness enhancement films, and barrier enhancement films.

[0028] The thickness of the transparent substrate 11 is not particularly limited, but is preferably, for example, 25 μm or more. The film thickness of the transparent substrate 11 is more preferably 40 μm or more. If the thickness of the transparent substrate 11 is 25 μm or more, the rigidity of the substrate itself can be ensured, and wrinkles are not easily generated even when stress is applied to the optical laminate 10. If the thickness of the transparent substrate 11 is 40 μm or more, wrinkles are even less likely to occur, which is preferable.

[0029] As described in the method for manufacturing the optical laminate below, when manufacturing the optical laminate 10 using a roll-to-roll method, the thickness of the transparent substrate 11 is preferably 1000 μm or less, and more preferably 600 μm or less. If the thickness of the transparent substrate 11 is 1000 μm or less, it is easier to wind the optical laminate 10 during and after manufacturing into a roll, thereby enabling efficient manufacturing of the optical laminate 10. Furthermore, if the thickness of the transparent substrate 11 is 1000 μm or less, it is possible to achieve thin-film and lightweight design of the optical laminate 10. If the thickness of the transparent substrate 11 is 600 μm or less, the optical laminate 10 can be manufactured more efficiently, and further thin-film and lightweight design can be achieved, which is preferable.

[0030] The optical functional layer 12 represents the optical functions. The optical functions referred to here are the functions that control the reflection, transmission, and refraction of light as properties, such as anti-reflection function, selective reflection function, anti-glare function, and lens function. The optical functional layer 12 can be any type of layer, such as an anti-reflective layer, a selective reflective layer, or an anti-glare layer. In this embodiment, an anti-reflective layer is formed as the optical functional layer 12.

[0031] The optical functional layer 12 is a laminate formed by sequentially depositing a high refractive index layer 12a and a low refractive index layer 12b from the transparent substrate 11 side. Furthermore, the number of high refractive index layer 12a and low refractive index layer 12b can be set to any number of layers, such as two or more, as in this embodiment.

[0032] In the optical stack 10 of this embodiment, the optical functional layer 12 comprises a stack formed by stacking a low-refractive-index layer 12b and a high-refractive-index layer 12a. Therefore, light incident from the low-refractive-index layer 12b side, such as ambient light, is diffused by the optical functional layer 12. Thus, an anti-reflection function can be obtained to prevent ambient light incident from the low-refractive-index layer 12b side from being reflected in one direction. Therefore, by simply providing such an optical stack 10, for example, on the display surface side of a display device, the reflection of ambient light can be suppressed, thereby improving the visibility of the display device.

[0033] The optical functional layer 12 contains materials containing inorganic oxides or inorganic nitrides. From the perspective of ease of acquisition and cost, silicon oxide (SiO2) can be used for the low refractive index layer 12b. A single layer of SiO2 is colorless and transparent. For example, the low refractive index layer 12b only needs to contain more than 50% by mass of SiO2.

[0034] The low refractive index layer 12b is also preferably, in addition to containing SiO2, it contains, for example, Na to improve durability, Zr, Al and N to improve hardness, and Zr and Al to improve alkali resistance.

[0035] The refractive index of the low refractive index layer 12b is preferably above 1.20 and below 1.60, and more preferably above 1.30 and below 1.50. Furthermore, the thickness of the low refractive index layer 12b can be in the range of 1 nm to 200 nm, as long as it is appropriately selected according to the wavelength range required for the anti-reflection function.

[0036] For example, niobium pentoxide (Nb₂O₅, refractive index 2.33), titanium oxide (TiO₂, refractive index 2.33 to 2.55), tungsten oxide (WO₃, refractive index 2.2), cerium oxide (CeO₂, refractive index 2.2), tantalum pentoxide (Ta₂O₅, refractive index 2.16), zinc oxide (ZnO, refractive index 2.1), indium tin oxide (ITO, refractive index 2.06), and zirconium oxide (ZrO₂, refractive index 2.2) can be used as the high refractive index layer 12a. Furthermore, when it is desired to impart conductive properties to the high refractive index layer 12a, ITO or indium zinc oxide (IZO) can also be used. The thickness of the high refractive index layer 12a can be, for example, between 1 nm and 200 nm, and the anti-reflection function can be appropriately selected according to the required wavelength range.

[0037] In the optical functional layer 12 of this embodiment, a layer containing niobium pentoxide (Nb₂O₅, refractive index 2.33) is used as the high refractive index layer 12a, and a layer containing silicon oxide (SiO₂) is used as the low refractive index layer 12b.

[0038] Furthermore, a hard coating or a bonding layer can also be formed between the transparent substrate 11 and the optical functional layer 12 in the optical laminate 10. The hard coating may consist only of adhesive resin, or it may contain adhesive resin and filler to a extent that does not impair transparency. As filler, it may contain organic substances, inorganic substances, or both.

[0039] The adhesive resin used for the hard coating is preferably a transparent resin, such as a resin that is cured by ultraviolet light or electron beam, i.e., an ionizing radiation-cured resin, a thermoplastic resin, or a thermosetting resin. Furthermore, the hard coating can be a single layer or formed by laminating multiple layers. Moreover, the hard coating can also be endowed with known properties such as ultraviolet absorption, antistatic properties, refractive index adjustment, and hardness adjustment.

[0040] The bonding layer is formed to improve the adhesion between the transparent substrate 11 (an organic material film) or hard coating layer and the optical functional layer 12 (an inorganic material film). The bonding layer is preferably a metal oxide or metal containing oxygen-deficient states. An oxygen-deficient metal oxide refers to a metal oxide in which the oxygen content is insufficient compared to its stoichiometric composition. Examples of oxygen-deficient metal oxides include SiOx, AlOx, TiOx, ZrOx, CeOx, MgOx, ZnOx, TaOx, SbOx, SnOx, and MnOx. Examples of metals include Si, Al, Ti, Zr, Ce, Mg, Zn, Ta, Sb, Sn, Mn, and In. The bonding layer may also be SiOx in which x is greater than 0 but less than 2.0.

[0041] From the viewpoint of maintaining transparency and obtaining good optical properties, the thickness of the bonding layer is preferably greater than 0 nm and less than 20 nm, and particularly preferably greater than 1 nm and less than 10 nm.

[0042] The marking layer 13 is formed in such a way that at least a portion overlaps with the defective portion D generated during the manufacturing stage of the optical functional layer 12. The identification layer 13 contains a semiconductor material with a reflectivity of 40% or more for light in the range of wavelengths from 400 nm to 700 nm.

[0043] As for the semiconductor material constituting the identification layer 13, examples include pure semiconductors composed of elemental substances, p-type or n-type semiconductors with trace amounts of group III or group V elements added to pure semiconductors, and compound semiconductors containing multiple elements.

[0044] The marking layer 13 in this embodiment uses a sputtered film formed by sputtering a material containing germanium or silicon. More specifically, examples include compounds containing 5% to 10% of germanium, iron silicates, or titanium silicates.

[0045] In terms of film formation speed and ease of acquisition compared to silicon, which is often used as a semiconductor, it is particularly preferable to form the marking layer 13 by sputtering germanium as a target. Germanium also has a higher film formation rate among semiconductor materials, so sputtering can be performed with lower power compared to other semiconductor materials. This helps to suppress thermal damage to the optical functional layer 12 during the formation of the marking layer 13.

[0046] The thickness of the marking layer 13 is not particularly limited as long as the desired reflectivity can be obtained; for example, it is preferably 10 nm or more and 30 nm or less. When the marking layer 13 is formed with a thickness exceeding 30 nm, there are concerns that the time required for film formation becomes longer, and correspondingly, excessive heat is applied during sputtering, thereby increasing the thermal damage to the optical functional layer 12. Furthermore, when the thickness of the marking layer 13 is less than 10 nm, there are concerns that the desired reflectivity cannot be obtained, and it is particularly difficult to detect visually.

[0047] The conductivity of the marking layer 13 only needs to be within the range that can suppress corona discharge, for example, above 1×10 3 (S / cm) and below 1×10 -8 (S / cm).

[0048] The marking layer 13 can be formed in a way that completely covers the planar shape of the defect portion D of the optical functional layer 12, or it can be formed in a way that only overlaps with a portion of the planar shape of the defect portion D. The film formation range can be appropriately selected by considering the ease of detection of the marking layer 13 in subsequent steps and the film formation speed of the marking layer 13.

[0049] As described above, according to the optical stack 10 of this embodiment, the marking layer 13 formed on the defect site D of the optical functional layer 12 is formed of a semiconductor material with a reflectivity of 40% or more for light in the wavelength range of 400 nm to 700 nm, such as visible light. This makes it easy to detect the defect site under visible light in subsequent steps, and when the optical stack 10 is subjected to corona treatment or other processes in subsequent steps, abnormal discharge toward the marking layer 13 can be effectively suppressed.

[0050] (Manufacturing method of optical laminates) Next, one embodiment of the manufacturing method of the optical laminate described in the above embodiments will be explained. In this embodiment, as an example of a method for manufacturing the optical laminate 10, a so-called roll-to-roll manufacturing example is described, in which the optical laminate 10 is manufactured by using a transparent substrate 11 wound into a roll and then wound into a roll.

[0051] First, a transparent substrate (substrate) 11, wound into a roll shape, is unwound. Next, an optical functional layer formation step is performed to form an optical functional layer 12 on one side 11a of the transparent substrate 11. Next, a defect inspection step is performed to check for defects in the formed optical functional layer 12. Then, if a defect is detected in the optical functional layer 12 during the defect inspection step, a defect area display step is performed to form a marking layer in the area containing the defect. Afterward, a surface treatment step is performed on the surface of the optical functional layer 12, and the formed optical laminate 10 is wound up.

[0052] Furthermore, it may also include a hard coating forming step of forming a hard coating on the transparent substrate 11 after rolling out the transparent substrate (substrate) 11, or a close-fitting layer forming step of forming a close-fitting layer. Additionally, it may also include an optical functional layer forming step of forming an anti-fouling layer after performing a surface treatment step.

[0053] In the manufacturing method of the optical stack 10 of this embodiment, the optical functional layer formation step, defect inspection step, defect area display step, and surface treatment step are preferably performed continuously while the optical stack is maintained under reduced pressure during manufacturing. When the optical stack is maintained under reduced pressure during manufacturing and the optical functional layer formation step, defect inspection step, defect area display step, and surface treatment step are performed continuously, for example, a known thin film forming apparatus can be used as a sputtering apparatus.

[0054] Figure 3 is a schematic diagram of an optical laminate manufacturing apparatus used in the optical laminate manufacturing method of this embodiment. As a manufacturing apparatus that can be used in the manufacturing method of the optical laminate in this embodiment, the optical laminate manufacturing apparatus 20 shown in FIG3 can be specifically exemplified. The optical multilayer manufacturing apparatus 20 includes a roll-out device 4, a sputtering device 1, a surface treatment device 2, and a roll-taking device 5. As shown in FIG3, the roll-out device 4, the sputtering device 1, the surface treatment device 2, and the roll-taking device 5 are connected sequentially. The optical multilayer manufacturing apparatus 20 is a roll-to-roll manufacturing apparatus, that is, the substrate is rolled out from the rolls, continuously passed through the connected devices, and then wound up, thereby continuously forming multiple layers on the substrate.

[0055] When manufacturing optical laminate 10 using a roll-to-roll optical laminate manufacturing apparatus 20, the conveying speed (linear speed) of the optical laminate 10 during manufacturing can be appropriately set. The conveying speed is preferably 0.5 m / min to 20 m / min, and more preferably 0.5 m / min to 10 m / min.

[0056] <Roller winding device> The roll-out device 4 has a chamber 34 with an internally designed as a specific depressurized environment, one or more vacuum pumps 21 (one in Figure 3) for venting the gas in the chamber 34 to create a depressurized environment, and a roll-out roller 23 and a guide roller 22 disposed in the chamber 34. As shown in Figure 3, the chamber 34 is connected to the chamber 31 of the sputtering device 1. A transparent substrate 11 is wound on a roll-out roller 23. The roll-out roller 23 supplies the transparent substrate 11 to the sputtering apparatus 1 at a specific conveying speed.

[0057] Sputtering apparatus The sputtering apparatus 1 shown in Figure 3 includes a chamber 31 with an internally designed to create a specific depressurized environment, one or more vacuum pumps 21 (two in Figure 3) that discharge the gas from the chamber 31 to create a depressurized environment, a film-forming roller 25, a plurality of guide rollers 22 (two in Figure 3), a plurality of film-forming sections 41 (41A, 41B, 41C in the example shown in Figure 4), and a defect detection section 42.

[0058] As shown in Figure 3, the film-forming roller 25, the guide roller 22, the film-forming section 41, and the defect detection section 42 are disposed in the chamber 31. The chamber 31 is connected to the chamber 34 of the roller winding device 4.

[0059] The film forming roller 25 and the guide roller 22 transport the transparent substrate 11 conveyed by the roller unwinding device 4 at a specific conveying speed, and supply the transparent substrate 11 on one side 11a of the transparent substrate 11 with an optical functional layer 12 formed thereon to the surface treatment device 2. In the sputtering apparatus 1 shown in Figure 3, a high refractive index layer 12a is formed on one side 11a of the transparent substrate 11 moving on the film-forming roller 25 by the film-forming section 41A, and a low refractive index layer 12b is formed on it by the film-forming section 41B, thereby forming an optical functional layer 12. Subsequently, the defect detection section 42 inspects the optical functional layer 12 for defects. When a defect is found in the optical functional layer 12, a marking layer 13 is formed at the defect location D by the film-forming section 41C (see Figures 1 and 2).

[0060] As shown in Figure 3, the film-forming sections 41 are arranged opposite to the outer peripheral surfaces of the film-forming roller 25 at a specific interval, and a plurality of them are provided in such a way that they surround the film-forming roller 25. The number of film-forming sections 41 is simply the sum of the total number of layers of high refractive index layer 12a and low refractive index layer 12b that form the optical functional layer 12 and the number of marking layers 13 formed.

[0061] When it is difficult to ensure the distance between adjacent film-forming sections 41 due to the large number of layers of high refractive index layer 12a and low refractive index layer 12b forming optical functional layer 12, a plurality of film-forming rollers 25 may be provided in the chamber 31, and film-forming sections 41 may be arranged around each film-forming roller 25.

[0062] When multiple film-forming rollers 25 are provided, guide rollers 22 may also be provided as needed. Multiple stage chambers 31 on which film-forming rollers 25 and film-forming sections 41 are provided can be connected. Furthermore, in order to easily ensure the distance between adjacent film-forming sections 41, the diameter of the film-forming rollers 25 can be appropriately changed.

[0063] Each film-forming portion 41 is provided with a specific target (not shown). A voltage is applied to the target using a known structure. In this embodiment, a gas supply portion (not shown) that supplies a specific reactive gas and a carrier gas to the target at a specific flow rate, and a known magnetic field generating source (not shown) that forms a magnetic field on the surface of the target are provided near the target.

[0064] The material of the target, as well as the type and flow rate of the reactive gas, can be appropriately determined based on the composition of the high refractive index layer 12a, the low refractive index layer 12b, and the marking layer 13 formed at the defect site D, which are formed on the transparent substrate 11 by passing between the film forming section 41 and the film forming roller 25.

[0065] For example, when forming a high-refractive-index layer 12a containing Nb₂O₅ using the film-forming section 41A, Nb is used as the target and O₂ is used as the reactive gas. Similarly, when forming a low-refractive-index layer 12b containing SiO₂ using the film-forming section 41B, Si is used as the target and O₂ is used as the reactive gas. Furthermore, when forming a Ge-containing layer 13 as a marker layer 13 on the defect site D using the film-forming section 41C, Ge is used as the target and Ar is used as the carrier gas.

[0066] In this embodiment, from the viewpoint of increasing the self-film formation speed, it is preferable to use magnetron sputtering as the sputtering method. Furthermore, sputtering is not limited to magnetron sputtering; it can also be used in two-electrode sputtering, which utilizes plasma generated by DC glow discharge or high frequency, or in three-electrode sputtering with an additional hot cathode.

[0067] The defect detection unit 42 is simply an optical monitor that detects defects in the optical functional layer 12 when defects exist after each layer of the optical functional layer 12 has been formed. This allows for confirmation of the presence or absence of defects in the formed optical functional layer 12. Examples of defects that may occur in the optical functional layer 12 include portions where optical properties do not meet required values, foreign objects, pinholes, etc. These defects can be detected by the optical monitor.

[0068] As an optical monitor constituting the defect detection unit 42, an example optical monitor may be used, which uses an optical head capable of scanning along the width direction of the optical laminate 10 at a right angle to the extension direction to measure the optical characteristics, such as the change in reflectivity, of the optical functional layer 12 formed on one surface 11a of the optical laminate 10, thereby detecting the defect location D. When the defect detection unit 42 detects the defect location D, it outputs the position information of the defect location D to the control unit (not shown).

[0069] The control unit (not shown) controls the film-forming direction of the film-forming unit 41C based on the input location information of the defect site D. Then, the film-forming unit 41C forms a semiconductor-containing marking layer 13 in a manner that overlaps with the defect site D. In this embodiment, the marking layer 13 contains germanium.

[0070] Surface treatment apparatus The surface treatment apparatus 2 shown in Figure 3 includes a chamber 32 with an internally designed depressurized environment, a canning roller 26, a plurality of (two in Figure 3) guide rollers 22, and a plasma discharge device 43. As shown in Figure 3, the canning roller 26, the guide rollers 22, and the plasma discharge device 43 are disposed within the chamber 32. As shown in Figure 3, the chamber 32 is connected to the chamber 35 of the roller winding device 5.

[0071] The canning roller 26 and the guide roller 22 transport the transparent substrate 11, which is formed with an optical functional layer 12 and a marking layer 13 when there is a defect D, which is conveyed by the self-sputtering device 1 at a specific conveying speed, and send the optical laminate 10, whose surface of the optical functional layer 12 has been treated, to the roller winding device 5.

[0072] The plasma discharge device 43 is a type of corona discharge device, as shown in Figure 3, and is arranged opposite to the outer peripheral surface of the can roller 26 at a specific interval. The plasma discharge device 43 ionizes the gas by glow discharge. Preferably, the gas is inexpensive and does not affect optical properties; for example, argon, oxygen, nitrogen, helium, etc. Argon is preferred because it has a larger mass, is chemically stable, and is readily available. In this embodiment, the plasma discharge device 43 is preferably a glow discharge device that ionizes argon gas by high-frequency plasma.

[0073] When the surface treatment of the optical functional layer 12 is performed by plasma discharge (corona discharge) using this plasma discharge device 43, the marking layer 13 formed in the presence of defective sites D is made of semiconductor material, such as germanium film, so the plasma discharge will not abnormally discharge toward the marking layer 13. Since the marking layer 13 is formed of semiconductor material, its conductivity is low, which can prevent abnormal plasma discharge toward the marking layer 13.

[0074] <Roller winding device> The roller winding device 5 shown in Figure 3 has a chamber 35 with an internally designed as a specific depressurization environment, one or more vacuum pumps 21 (one in Figure 3) for venting the gas in the chamber 35 to create a depressurization environment, and a winding roller 24 and a guide roller 22 disposed in the chamber 35.

[0075] An optical laminate 10 is wound on a take-up roller 24. The take-up roller 24 and the guide roller 22 take up the optical laminate 10 at a specific take-up speed.

[0076] The vacuum pumps 21 included in the optical laminate manufacturing apparatus 20 shown in Figure 3 can be, for example, dry pumps, oil swirl pumps, turbomolecular pumps, oil diffusion pumps, cryogenic pumps, sputtering ion pumps, and suction pumps. The vacuum pumps 21 can be appropriately selected to create the desired depressurization state in each of the chambers 31, 32, 34, and 35, or they can be used in combination.

[0077] Next, a method for continuously performing the optical functional layer formation step, the defect inspection step, the defect area display step, and the surface treatment step by maintaining the optical laminate 10 under reduced pressure during manufacturing using the optical laminate manufacturing apparatus 20 shown in FIG3. First, a roll-out roller 23 with a transparent substrate 11 wound on it is installed in the chamber 34 of the roll-out device 4. Then, the roll-out roller 23 and the guide roller 22 are rotated to deliver the transparent substrate 11 to the sputtering device 1 at a specific conveying speed.

[0078] Next, within the chamber 31 of the sputtering apparatus 1, an optical functional layer formation step, a defect inspection step, and a defect area display step are performed as needed. Specifically, the film-forming roller 25 and the guide roller 22 are rotated to transport the transparent substrate 11 at a specific conveying speed, and simultaneously an optical functional layer 12 is formed on one side 11a of the transparent substrate 11 moving on the film-forming roller 25.

[0079] In this embodiment, a high refractive index layer 12a is deposited by film-forming portion 41A, and a low refractive index layer 12b is deposited by film-forming portion 41B, and the high refractive index layer 12a and the low refractive index layer 12b are deposited alternately. In this way, for example, an optical functional layer 12 as an anti-reflection layer is formed.

[0080] The sputtering pressure during the formation of the optical functional layer 12 varies depending on the metal being sputtered, and can be below 2 Pa, preferably below 1 Pa, more preferably below 0.6 Pa, and especially preferably below 0.2 Pa. If the sputtering pressure is below 1 Pa under reduced pressure, the mean free path of the film-forming molecules becomes longer, and the film accumulates at a higher energy level, thus forming a denser and better film.

[0081] Next, the optical functional layer 12 is scanned by a defect detection unit 42, for example, an optical monitor, to detect whether there are any defects in the optical functional layer 12 (defect inspection step). Then, when a defective part D is found in the optical functional layer 12, the defect detection unit 42 outputs the location information of the defective part D to the control unit (not shown).

[0082] Next, the film forming unit 41C forms a semiconductor-containing identification layer 13 by overlapping with the defect region D based on the position information of the defect region D input to the control unit (not shown). In this embodiment, the semiconductor includes germanium (defect region display step).

[0083] Next, the optical functional layer 12 is subjected to a surface treatment step within the chamber 32 of the surface treatment apparatus 2. In this embodiment, the transparent substrate 11 on which the optical functional layer 12 is formed, obtained by the optical functional layer formation step, is kept under reduced pressure in a manner that prevents it from contacting the atmosphere, and the surface treatment step is performed continuously.

[0084] In the surface treatment step, the can roller 26 and guide roller 22 are rotated to transport the transparent substrate 11 on which the optical functional layer 12 is formed at a specific conveying speed, and the surface of the optical functional layer 12 moving on the can roller 26 is subjected to electrical discharge treatment. This surface treatment step is performed, for example, after the manufacture of the optical laminate 10, as a surface cleaning step for the optical functional layer 12 to improve adhesion when, for example, a protective film is laminated to the surface of the optical functional layer 12, or when other layers are formed by overlapping the optical functional layer 12. As a layer formed by overlapping the optical functional layer 12, an antifouling layer formed by vapor deposition using fluorine compounds or silicone compounds can be exemplified.

[0085] As a surface treatment method for the optical functional layer 12, for example, glow discharge treatment, plasma treatment, ion etching, alkaline treatment, etc. can be used. Among these, glow discharge treatment is preferred because it can perform large-area processing.

[0086] If a discharge process is performed on the surface of the optical functional layer 12, the surface of the optical functional layer 12 is etched, and the surface roughness of the optical functional layer 12 changes. The surface roughness Ra of the optical functional layer 12 can be controlled by making the cumulative output during the discharge process within an appropriate range.

[0087] In this surface treatment step, when the optical functional layer 12 is surface treated by discharge, the marking layer 13 formed when there is a defect D is made of a semiconductor material, such as a germanium film, so there will be no abnormal discharge to the marking layer 13. Since the marking layer 13 is formed of a semiconductor material, its conductivity is low, which can prevent abnormal discharge to the marking layer 13 from causing further defects in the optical functional layer 12.

[0088] By means of the above method, an optical stack 10 having an optical functional layer 12 formed by sputtering can be obtained. Subsequently, the optical stack 10 is fed to the roll take-up device 5 by means of the rotation of the guide roller 22. Subsequently, within the chamber 35 of the roll take-up device 5, the optical laminate 10 is wound onto the take-up roll 24 by the rotation of the take-up roll 24 and the guide roll 22.

[0089] In the optical stack 10 obtained in this way, when there is a defect in the optical functional layer 12, it overlaps with the defect site D to form a marking layer 13. This marking layer is a semiconductor, such as a germanium film, and can be easily detected by visible light. Therefore, when avoiding this defect site D in subsequent steps and using the optical stack 10, the defect site D can be easily identified by visual inspection or by using a simple detector with visible light.

[0090] Furthermore, as shown in Figure 3, the surface treatment step may not be a continuous step with the formation of the optical functional layer. For example, it may continue until the optical functional layer 12 is formed and temporarily rolled up, and then the protective film is laminated after the surface treatment step is performed in another location, or other functional layers may be formed on the optical functional layer 12.

[0091] Furthermore, in the optical laminate 10 of this embodiment, various layers may be provided as needed on the other side of the transparent substrate 11 opposite to the side 11a on which the optical functional layer 12 is formed. For example, an adhesive layer for bonding with other components may also be provided. Additionally, other optical films may be provided via this adhesive layer. Examples of other optical films include polarizing films, phase difference compensation films, and films that function as half-wavelength plates or quarter-wavelength plates.

[0092] Alternatively, a layer with functions such as anti-reflection, selective reflection, anti-glare, polarization, phase difference compensation, viewing angle compensation or magnification, light guiding, diffusion, brightness enhancement, hue adjustment, and conductivity can be directly formed on the other side of a transparent substrate. Furthermore, the shape of the optical laminate 10 can be a smooth shape, or it can be a shape with a moth's eye or a nano-scale uneven structure that performs anti-glare function. It can also be a geometric shape ranging from micrometers to millimeters, such as a lens or prism. For example, the shape can be formed by a combination of photolithography and etching, shape transfer, hot pressing, etc. In this embodiment, the film is formed by vapor deposition, etc., so even when the substrate has an uneven shape, the uneven shape can be maintained.

[0093] The optical laminate 10 of this embodiment can be used as an anti-reflective film on the display surface of an image display unit such as a liquid crystal display panel or an organic EL (electroluminescence) display panel. In addition, the optical laminate 10 can also be applied to window glass or goggles, the light-receiving surface of solar cells, the screen of a smartphone or the display of a personal computer, information input terminals, tablet terminals, AR (Augmented Reality) devices, VR (Virtual Reality) devices, electro-optical display panels, glass table surfaces, game consoles, operating assistance devices for airplanes or trains, navigation systems, instrument panels, and the surfaces of optical sensors.

[0094] The embodiments of the present invention have been described above, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, and are similarly included in the scope of the invention described in the claims and their equivalents. Example

[0095] First, a transparent substrate containing triacetyl cellulose (TAC) with a thickness of 80 μm is prepared. Next, a 5 μm thick hard coating containing an ultraviolet-curable resin composition is formed on the transparent substrate. Then, on the hard coating, using a Si target and an Nb target as sputtering targets, an optical functional layer (anti-reflection layer) is formed using a mixed gas of argon and oxygen via reactive sputtering. Specifically, an optical functional layer is formed by sequentially overlaying a low-refractive-index layer containing SiO₂ (layer 1), a high-refractive-index layer containing Nb₂O₅ (layer 2), a low-refractive-index layer containing SiO₂ (layer 3), a high-refractive-index layer containing Nb₂O₅ (layer 4), and a low-refractive-index layer containing SiO₂ (layer 5) on the hard coating.

[0096] Subsequently, using Ge (Example 1), FeSi (Fe10%) (Example 2), Cu (Comparative Example 1), Ag (Comparative Example 2), and Cr (Comparative Example 3) as sputtering targets, thin films of each example (marker layer) and comparative example (metal film) were formed by DC sputtering at an output of 5 W / cm2 and under argon gas, with a film thickness of 20 nm, overlapping with the optical functional layer. The following tests were conducted using the optical laminates (samples) of Examples 1, 2 and Comparative Examples 1-3 obtained therefrom.

[0097] (1) Abnormal discharge test during corona treatment Corona treatment device: CORONA STATION (manufactured by Kasuga Electric Co., Ltd.), High-frequency power supply: AGF-012 (manufactured by Kasuga Electric Co., Ltd.) Output setting: 10 Workbench speed: 20 Under the above conditions, visually confirm whether there is any abnormal discharge. (2) Measurement of surface resistivity of the labeling layer (example) and the metal film (comparative example) Surface resistivity meter: Loresta GX (manufactured by Nittoseiko Analytech Co., Ltd.) (3) Testing of the labeling layer (example) and the metal film (comparative example) (3-1: Test 1) Using the following measuring apparatus, it is determined whether a marking layer containing a semiconductor can be detected. The measuring apparatus includes: a measuring unit that irradiates light onto a film and measures the light transmitted or reflected by the film; and a moving mechanism that enables the measuring unit to move along a first direction intersecting the film transport direction; and the measuring unit has a light-projecting unit that irradiates light onto the film, an integrating sphere that focuses the light from the film, and a light-receiving unit that receives the light focused by the integrating sphere. The test is performed 10 times, and the case where all tests can be performed is defined as acceptable, and the case where there is a test failure is defined as unacceptable. (3-2: Test 2) Visually confirm the visibility of the marking layer under visible light. Marking layers that are easily distinguishable from their surroundings are considered acceptable, while those that are difficult to distinguish are considered unacceptable. (4) Measurement of reflectivity of the labeling layer (example) and the metal film (comparative example) Spectrophotometer: U3900 (manufactured by Hitachi High-Tech Science Co., Ltd.) The test results of (1) to (3) are shown in Table 1. Also, the test results of (4) are shown in Figure 4.

[0098] [Table 1] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 target Ge FeSi (Fe10%) Cu Ag Cr Film formation rate (nm / sec) 0.213 0.105 0.301 0.665 0.157 Abnormal discharge none none have have have Surface resistivity (Ω / ) 2.3×10⁸ 1.2×10⁵ 2.2×10⁰ 1.7×10⁰ 1.7×10 2 Test 1 Can Can No Can Can Test 2 Can Can No Can Can

[0099] According to the results shown in Table 1, in the abnormal discharge test, the optical stacks with a marking layer formed using semiconductors (Examples 1 and 2) did not produce abnormal discharge even after corona treatment. On the other hand, the optical stacks with metal films formed (Comparative Examples 1 to 3) all produced abnormal discharge, resulting in damage to the optical functional layers. Furthermore, in the testing, the metal film of Comparative Example 1 was difficult to detect. Therefore, it is confirmed that Examples 1 and 2, which use a semiconductor film as the marking layer, satisfy both the prevention of abnormal discharge and ease of detection.

[0100] On the other hand, based on the results shown in Figure 4, it is confirmed that in Examples 1 and 2, which use semiconductor films as marker layers, the variation in reflectivity is relatively small in the entire region from wavelength 370 nm to 790 nm.

[0101] 1: Sputtering apparatus 2: Surface treatment device 4: Roller winding device 5: Roller winding device 10: Optical laminates 11: Transparent substrate 11a: One side 12: Optical Functional Layer 12a: High refractive index layer 12b: Low refractive index layer 13: Identification Layer 20: Manufacturing equipment 21: Vacuum pump 22: Guide roller 23: Rollout Roller 24: Take-up roller 25: Film forming roller 26: Can roller 31: Chamber 32: Chamber 34: Chamber 35: Chamber 41: Film-forming part 41A: Film-forming section 41B: Film-forming part 41C: Film-forming part 42: Defect Detection Department 43: Plasma discharge device D: Defective area

Claims

1. An optical laminate, characterized in that it is formed by laminating a substrate and an optical functional layer, wherein the optical functional layer comprises an inorganic oxide or an inorganic nitride, and a marking layer is partially formed on the surface of the optical functional layer, wherein the marking layer comprises a semiconductor material and has a reflectivity of 40% or more for light in the wavelength range of 400 nm to 700 nm, wherein the marking layer is formed by at least a portion overlapping a defect portion of the optical functional layer.

2. The optical stack as claimed in claim 1, wherein the aforementioned marking layer comprises germanium or silicon.

3. The optical laminate as claimed in claim 1 or 2, wherein the aforementioned marking layer is a sputtered film formed by sputtering.

4. The optical laminate as claimed in claim 1 or 2, wherein the optical laminate is an anti-reflective film, and the optical functional layer comprises a laminate formed by alternating layers of low refractive index and high refractive index.

5. A method for manufacturing an optical laminate, characterized in that it is a method for manufacturing an optical laminate as described in any one of claims 1 to 4, comprising: The optical functional layer forming step involves forming the optical functional layer on the aforementioned substrate; The defect inspection procedure involves inspecting for defects in the aforementioned optical functional layers. The defect area display step involves forming the identification layer in the area containing the defect when a defect is detected in the defect inspection step.

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