Articles with anti-glare surfaces having sloped transitions and related methods

Abstract

Described herein is an article having a scattering region designed to exhibit antiglare performance attributes. The scattering region includes a plurality of structures extending outward from a ground plane of a first major surface. Each of the plurality of structures includes a sloped portion extending from the ground plane and a peak portion located at the peak height of the structure. The sloped portions of the plurality of structures occupy more than 5% of the total surface area of ​​the scattering region. A 1×1 mm 2 scattering region 2 The Abbott-Firestone curve characterizing the section comprises an intermediate section between the section representing the ground plane and the peak section, which has an average gradient of less than 420% / µm and greater than 5% / µm.

Description

Description of Related Applications

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Patent Application No. 63 / 420222, filed October 28, 2022, and U.S. Provisional Patent Application No. 63 / 542398, filed October 4, 2023, the contents of which are relied upon and incorporated herein by reference in their entirety. [Technical Field]

[0002] SUMMARY The present disclosure relates to articles with anti-glare surfaces having sloped transitions and methods for making the same. [Background technology]

[0003] Substrates that are transparent to visible light are used to cover displays in display articles. Such display articles include smartphones, tablets, televisions, computer monitors, and in-vehicle displays. The displays are often liquid crystal displays or organic light-emitting diodes, among others. The transparency of the substrate allows users of the device to view the display while protecting it. Glare is a phenomenon associated with a degraded viewing experience in the presence of bright light sources. In addition, reflections from the surroundings, rather than the bright light source, can also contribute to display viewing degradation. For example, a user's own visually noticeable reflection or light from the surrounding environment can be distracting, reduce visibility, and cause eye fatigue.

[0004] Several technologies exist to reduce glare, including anti-reflective coatings and anti-glare technologies. Anti-reflective coatings can reduce glare by directly reducing the amount of overall reflection. However, certain existing anti-reflective coatings may not be able to reduce such reflections sufficiently across the entire visible spectrum to make them unnoticeable to the user. Anti-glare technologies attempt to spread the reflection of light over a wide range of angles, reducing the peak intensity of the reflection and making distracting reflected images less noticeable to the user. However, if the reflection angle is too large, haze can become relatively high, which can reduce the contrast of the displayed image. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, alternatives to existing anti-glare and anti-reflection coating technologies that allow for better control of the angular distribution of scattered light would be beneficial. [Means for solving the problem]

[0006] Aspect (1) of the present disclosure provides a substrate having a first major surface; a second major surface opposite the first major surface; and a scattering region formed within the first major surface, wherein within the scattering region, the first major surface includes a plurality of structures extending outward from a ground plane of the first major surface, each of the plurality of structures extending from the ground plane to a peak height, each of the plurality of structures including a sloping portion extending from the ground plane and a peak portion disposed at the peak height of the structure, the sloping portions of the plurality of structures occupying more than 5% of the total surface area of ​​the scattering region, and the scattering region is formed within a 1×1 mm 2 area of ​​the scattering region. 2 The article includes a substrate, wherein an Abbott-Firestone curve characterizing the portion includes: (a) a first portion representing an area of ​​the scattering region located closest to the ground plane; (b) a second portion representing a peak portion of a plurality of structures; and (c) an intermediate portion extending between the first portion and the second portion, the intermediate portion having an average gradient of less than 420% / μm and greater than 5% / μm.

[0007] Aspect (2) of the present disclosure relates to an article according to aspect (1), wherein the slanted portion occupies more than 50% of the total surface area of ​​the scattering region.

[0008] A third aspect of the present disclosure relates to an article according to the first aspect, wherein at least some of the peaks are etched depth portions that are located within 20 nm of a maximum peak height relative to the ground plane, and the etched depth portions occupy less than 60% of the total surface area of ​​the scattering region.

[0009] A fourth aspect of the present disclosure relates to an article according to the third aspect, wherein the etching depth portion occupies less than 40% of the total surface area of ​​the scattering region.

[0010] Aspect (5) of the present disclosure relates to an article according to any one of aspects (1) to (4), wherein the plurality of structures have a maximum feature size of 1 μm or more and less than 200 μm.

[0011] A sixth aspect of the present disclosure relates to an article according to any one of the first to fifth aspects, wherein at least some of the sloping portions extend a lateral distance between the ground plane and the peak portion of at least 1.0 μm and at most 10 μm, and the lateral distance over which the sloping portions extend is measured in a direction parallel to the surface normal of the sloping portions and parallel to the ground plane.

[0012] A seventh aspect of the present disclosure relates to the article according to the sixth aspect, wherein the lateral distance is 3.0 μm or more.

[0013] An embodiment (8) of the present disclosure relates to an article according to any of embodiments (6) to (7), wherein each of the sloping portions includes a first edge positioned proximate the ground plane and a second edge positioned proximate the peak portion, and the slope of the first major surface varies along a direction over a lateral distance of 1 μm at both the first edge and the second edge.

[0014] A ninth aspect of the present disclosure relates to an article according to any one of the first to eighth aspects, wherein the first and second portions of the Abbott-Firestone curve are vertical portions having a gradient of greater than 350% / μm.

[0015] A tenth aspect of the present disclosure relates to the article of the nineteenth aspect, wherein some of the peak portions are located within 20 nm of a maximum peak height relative to the ground plane, and the peak portions are represented by a second portion of the Abbott-Firestone curve, and the Abbott-Firestone curve includes a third vertical portion representing the peak portions located at peak heights between the ground plane and the maximum peak height.

[0016] An embodiment (11) of the present disclosure relates to the article according to embodiment (10), wherein the Abbott-Firestone curve further includes a fourth vertical portion representing an additional peak portion disposed at a peak height between the ground plane and the maximum peak height other than the height associated with the third vertical portion, and the intermediate portions include a first intermediate portion disposed between the first portion and the third vertical portion, a second intermediate portion disposed between the third vertical portion and the fourth vertical portion, and a third intermediate portion disposed between the fourth vertical portion and the second portion.

[0017] A twelfth aspect of the present disclosure relates to the article according to the eleventh aspect, wherein each of the first intermediate portion, the second intermediate portion, and the third intermediate portion is either (a) a segment of the Abbott-Firestone curve at least 50 nm in height, having an average slope at least 50% / μm less than the adjacent vertical portion, or (b) an inflection point of the Abbott-Firestone curve.

[0018] An embodiment (13) of the present disclosure relates to an article according to any one of embodiments (1) to (12), wherein the article exhibits a transmission haze of 3.5% or less and a sparkle of 2.5% or less measured at 140 ppi.

[0019] An embodiment (14) of the present disclosure is an article having a bidirectional reflectance distribution function ("BRDF") of 1.2×10 at a scattering angle of 30° relative to the specular reflection direction, measured from white light incident on the first major surface at an incident angle of 10°. -4 sr -1 The present invention relates to an article according to any one of aspects (1) to (13), which exhibits a strength of less than 1000 kJ / cm.

[0020] Aspect (15) of the present disclosure relates to an article according to any of aspects (1) to (14), wherein a first average modulation transfer function of the article, averaged over spatial frequencies of 1.67 cycles / mm, 4.11 cycles / mm, 7.33 cycles / mm, 10.38 cycles / mm, and 13.08 cycles / mm, is at least 0.7 when the article is viewed at a viewing angle of 0° and light having a luminance of 45,000 lux is incident on the first major surface at an angle of incidence of 20°.

[0021] Aspect (16) of the present disclosure relates to an article according to any of aspects (1) to (15), wherein the scattering region exhibits 40% or less trace visibility after 100 cycles of a pad applying a 270 g force to the CS8 material against the scattering region along the trace.

[0022] An embodiment (17) of the present disclosure provides a substrate having a first major surface; a second major surface opposite the first major surface; and a scattering region formed within the first major surface, wherein within the scattering region, the first major surface includes a plurality of structures extending outward from a ground plane of the first major surface, each of the plurality of structures extending from the ground plane to a peak height, (a) each of the plurality of structures includes a sloping portion extending from the ground plane and a peak portion located at the peak height of the structure, such that the scattering region includes the plurality of sloping portions and the plurality of peak portions, (b) at least some of the sloping portions extend a lateral distance between the ground plane and the peak portion that is greater than or equal to 1.0 μm and less than or equal to 10 μm, (c) the lateral distance over which the sloping portions extend is parallel to a surface normal of the sloping portions and is measured in a direction parallel to the ground plane, (d) the sloping portions of the plurality of structures occupy more than 5% of the total surface area of ​​the scattering region, and (e) the scattering region includes a 1×1 mm 2 The Abbott-Firestone curve characterizing the portion relates to an article having a substrate that does not include any horizontal portion of at least 0.05 μm in height having a gradient of less than 40% / μm in magnitude between the height representing the ground plane and the peak height of the scattering region.

[0023] An embodiment (18) of the present disclosure relates to an article according to embodiment (17), wherein the slanted portion occupies more than 5% of the total surface area of ​​the scattering region.

[0024] Aspect (19) of the present disclosure relates to an article according to any one of aspects (17) to (18), wherein at least some of the plurality of peak portions are etch depth portions that are located within 20 nm of a maximum peak height relative to the ground plane, and the etch depth portions occupy less than 60% of the total surface area of ​​the scattering region.

[0025] An embodiment (20) of the present disclosure relates to an article according to embodiment (19), wherein the etched depth portion occupies less than 40% of the total surface area of ​​the scattering region.

[0026] A twenty-first aspect of the present disclosure relates to an article according to any one of the seventeenth to twenty-first aspects, wherein the plurality of structures have a maximum feature size of 1 μm or more and less than 200 μm.

[0027] An embodiment (22) of the present disclosure relates to an article according to any of embodiments (17) to (21), wherein the sloped portion of each structure includes a first edge positioned proximate the ground plane and a second edge positioned proximate a peak portion of the structure, and the slope of the first major surface varies along a direction over a lateral distance of 1 μm at both the first edge and the second edge.

[0028] Aspect (23) of the present disclosure relates to an article according to any of aspects (17) to (22), wherein the Abbott-Firestone curve comprises a first portion representing an area of ​​the scattering region located closest to the ground plane, a second portion representing peak portions of the plurality of structures, and an intermediate portion extending between the first and second portions, the intermediate portion having an average slope of less than 420% / μm and greater than 5% / μm, the first and second portions of the Abbott-Firestone curve being vertical portions having slopes of magnitude greater than 350% / μm, and some of the peak portions being located within 20 nm of a maximum peak height, the peak portions being represented by the second portion of the Abbott-Firestone curve.

[0029] An embodiment (24) of the present disclosure relates to the article according to embodiment (23), wherein the Abbott-Firestone curve includes a third vertical portion representing a peak portion located at a height between the ground plane and the maximum peak height.

[0030] Aspect (25) of the present disclosure relates to an article according to aspect (24), wherein the Abbott-Firestone curve further includes a fourth vertical portion representing an additional peak portion disposed at a peak height between the ground plane and the maximum peak height other than the height associated with the third vertical portion, and the intermediate portions include a first intermediate portion disposed between the first portion and the third vertical portion, a second intermediate portion disposed between the third vertical portion and the fourth vertical portion, and a third intermediate portion disposed between the fourth vertical portion and the second portion.

[0031] An embodiment (26) of the present disclosure relates to an article according to embodiment (25), wherein each of the first intermediate portion, the second intermediate portion, and the third intermediate portion is either (a) a segment of the Abbott-Firestone curve at least 50 nm in height having an average slope at least 50% / μm less than the adjacent vertical portion, or (b) an inflection point of the Abbott-Firestone curve.

[0032] An embodiment (27) of the present disclosure relates to an article according to any one of embodiments (17) to (26), wherein the article exhibits a transmission haze of 3.5% or less and a sparkle of 2.5% or less measured at 140 ppi.

[0033] An embodiment (28) of the present disclosure is directed to an article having a bidirectional reflectance distribution function ("BRDF") of 1.2×10 at a scattering angle of 30° relative to the specular reflection direction, measured from white light incident on the first major surface at an incident angle of 10°. -4 sr -1 The present invention relates to an article according to any one of aspects (17) to (27), which exhibits a strength of less than

[0034] An embodiment (29) of the present disclosure relates to an article according to any of embodiments (17) to (28), wherein a first average modulation transfer function of the article averaged over spatial frequencies of 1.67 cycles / mm, 4.11 cycles / mm, 7.33 cycles / mm, 10.38 cycles / mm, and 13.08 cycles / mm is at least 0.7 when the article is viewed at a viewing angle of 0° and light having a luminance of 45,000 lux is incident on the first major surface at an angle of incidence of 20°.

[0035] An embodiment (30) of the present disclosure relates to an article according to any of embodiments (17)-(29), wherein the scattering region exhibits 40% or less trace visibility after 100 cycles of a pad applying a 270 g force to the CS8 material against the scattering region along the trace.

[0036] Aspect (31) of the present disclosure relates to a method of forming a scattering region of a substrate for a display article, the method comprising: determining a pattern of a plurality of structures on a first major surface of the substrate, each of the plurality of structures having a surface area disposed at a height measured relative to a ground plane spanning the display article; disposing one or more etching masks on the first major surface, the etching masks enabling etching only on select areas of the first major surface to form at least some of the plurality of structures; after disposing each of the one or more etching masks on the first major surface, contacting the display article with an etching solution for a period of time to form the plurality of structures in a basic etching step; removing the one or more etching masks from the first major surface; and exposing the entire scattering region to a secondary etching solution, such that the plurality of structures include sloped portions and have rounded corners.

[0037] An embodiment (32) of the present disclosure relates to the method of embodiment (31), wherein exposing the entire scattering region to a secondary etching solution comprises immersing the article in a secondary etching solution having a concentration ratio of HF to HCl ranging from 0.5M HF / 0.5M HCl to 3M HF / 3M HCl, such that the etching rate of the article is greater than 0.5 μm / min.

[0038] An embodiment (33) of the present disclosure relates to the method of embodiment (31), wherein exposing the entire scattering region to a secondary etchant comprises spraying the article with a secondary etchant having a concentration ratio of HF to HCl of 16 mM HF / 20 mM HCl to 160 mM HF / 200 mM HCl to achieve an etch rate of 0.1 μm / min to 1 μm / min.

[0039] Aspect (34) of the present disclosure relates to any of the methods of aspects (31) to (33), wherein the step of exposing the entire scattering region to a secondary etching solution is carried out for a secondary etching period of 20 minutes or less, such that 20 μm or less of material is removed from the scattering region.

[0040] An embodiment (35) of the present disclosure relates to the method of any one of embodiments (31) to (34), wherein after the basic etching step, the plurality of structures includes a plurality of regions of the first main surface that are disposed at different heights relative to the ground plane, and the heights differ from one another by 20 nm to 200 nm in a direction perpendicular to the ground plane.

[0041] Aspect (36) of the present disclosure relates to any of the methods of aspects (31) to (35), wherein the step of exposing the entire scattering region to a secondary etching solution reduces the fill fraction of the scattering region, which is comprised of portions of the article not etched in the basic etching step, by at least 5%.

[0042] It is to be understood that both the foregoing general description and the following detailed description are exemplary only and are intended to provide an overview or framework for understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description, serve to explain the principles and operation of the various embodiments. [Brief explanation of the drawings]

[0043] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate several aspects of the invention and, together with the description, serve to explain the principles of the invention. [Figure 1] 1 is a perspective view of a display article according to one or more embodiments of the present disclosure. [Figure 2] 2 is a schematic diagram illustrating a portion of the scattering region of the display article of FIG. 1 in accordance with one or more embodiments of the present disclosure. [Figure 3A] 3 is a schematic diagram illustrating the height profile of the scattering region shown in FIG. 2, in accordance with one or more embodiments of the present disclosure. [Figure 3B] 3A-3C are cross-sectional views of the transition between two scattering regions at different heights shown in FIG. 2, in accordance with one or more embodiments of the present disclosure. [Figure 4] 1 is a flow diagram of a method for manufacturing a display article with a scattering region including a structure with a sloped transition region, according to one or more embodiments of the present disclosure. [Figure 5A] FIG. 1 illustrates a 2D cross-sectional height profile of a structure of an article formed without feature rounding, in accordance with one or more embodiments of the present disclosure. [Figure 5B] FIG. 1 illustrates a 2D cross-sectional height profile of a structure of an article formed with feature rounding through mask undercutting, in accordance with one or more embodiments of the present disclosure. [Figure 5C] FIG. 1 illustrates a 2D cross-sectional height profile of a structure of an article formed with feature rounding by secondary etching, in accordance with one or more embodiments of the present disclosure. [Figure 6A] FIG. 10 shows a surface height profile and a surface height histogram associated with Example 5, in accordance with one or more embodiments of the present disclosure. [Figure 6B] FIG. 1 shows a surface height profile and a surface height histogram associated with Example 1, in accordance with one or more embodiments of the present disclosure. [Figure 7] 10A-10C are plots showing Abbott-Firestone ("AF") curves generated from 1 x 1 mm portions of the scattering regions of Examples 1-5, according to one or more embodiments of the present disclosure. [Figure 8] 1 is a schematic diagram illustrating an apparatus for measuring the washout performance of an article, according to one or more embodiments of the present disclosure. [Figure 9]1 is a schematic diagram illustrating a vehicle interior with a display and an ambient light source emitting light that is incident on and scattered from the display, in accordance with one or more embodiments of the present disclosure; [Figure 10] 1 is a plot of the washout performance index as a function of the water contact angle of the substrate before masking for Examples 1-5, according to one or more embodiments of the present disclosure. [Figure 11A] 1 is a plot showing AF curves for Examples 6-7 compared to a control formed with the same pattern without feature rounding, in accordance with one or more embodiments of the present disclosure. [Figure 11B] 1 is a plot showing AF curves for Examples 8-9 compared to a control formed with the same pattern without feature rounding, in accordance with one or more embodiments of the present disclosure. [Figure 11C] 1 is a plot showing AF curves for Examples 10-11 compared to a control formed with the same pattern without feature rounding, in accordance with one or more embodiments of the present disclosure. [Figure 12A] 10 is a scanning electron microscope image of a surface structure associated with Example 9, according to one or more embodiments of the present disclosure. [Figure 12B] 10 is a scanning electron microscope image of a surface structure associated with Example 10, according to one or more embodiments of the present disclosure. [Figure 12C] 11 is a scanning electron microscope image of a surface structure associated with Example 11, according to one or more embodiments of the present disclosure. [Figure 13A] FIG. 10 shows a surface height profile and histogram representing a portion of a control sample that did not undergo feature rounding, in accordance with one or more embodiments of the present disclosure. [Figure 13B] FIG. 10 shows a surface height profile and histogram representing a portion of a sample associated with Example 12, in accordance with one or more embodiments of the present disclosure. [Figure 13C] FIG. 10 shows a surface height profile and histogram representing a portion of a sample associated with Example 13, in accordance with one or more embodiments of the present disclosure. [Figure 13D] FIG. 10 shows a surface height profile and histogram representing a portion of a sample associated with Example 14, in accordance with one or more embodiments of the present disclosure. [Figure 14] 13A and 13B are plots showing AF curves for Examples 12-14 and the control sample depicted in FIG. 13A, according to one or more embodiments of the present disclosure. [Figure 15] Plot of Bidirectional Reflectance Distribution Function ("BRDF") amplitude as a function of scattering angle for Examples 12-14 and a control sample, according to one or more embodiments of the present disclosure. [Figure 16A] FIG. 10 shows a surface height profile and histogram representing a portion of a control sample that did not undergo feature rounding, in accordance with one or more embodiments of the present disclosure. [Figure 16B] FIG. 10 shows a surface height profile and histogram representing a portion of a sample associated with Example 15, in accordance with one or more embodiments of the present disclosure. [Figure 16C] FIG. 10 shows a surface height profile and histogram representing a portion of a sample associated with Example 16, in accordance with one or more embodiments of the present disclosure. [Figure 16D] FIG. 10 shows a surface height profile and histogram representing a portion of a sample associated with Example 17, in accordance with one or more embodiments of the present disclosure. [Figure 17] 16A and 16B are plots showing AF curves for Examples 15-17 and the control sample depicted in FIG. 16A, according to one or more embodiments of the present disclosure. [Figure 18] Plot of bidirectional reflectance distribution function ("BRDF") amplitude as a function of scattering angle for Examples 15-17 and a control sample, according to one or more embodiments of the present disclosure. [Figure 19] FIG. 10 shows a surface height profile and histogram associated with another control sample without feature rounding that was tested for wear performance, in accordance with one or more embodiments of the present disclosure. [Figure 20] FIG. 20 shows a surface height profile and histogram associated with Example 23, in accordance with one or more embodiments of the present disclosure. [Figure 21A] 19 after undergoing abrasion testing, according to one or more embodiments of the present disclosure. [Figure 21B]21 is an image of the sample shown in FIG. 20 after undergoing abrasion testing, according to one or more embodiments of the present disclosure. [Figure 22] FIG. 21C shows a histogram of trace visibility values ​​calculated from images of the samples shown in FIGS. 21A and 21B after abrasion testing, according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0044] Referring generally to the drawings, a component is described herein having a surface with a scattering region including a plurality of structures. The structures extend outward from a ground plane to a peak height in a direction perpendicular to the ground plane. As a result of performing the fabrication methods described herein, each of the plurality of structures includes a sloped portion extending from the ground plane and a peak portion disposed at the peak height relative to the ground plane. A scattering region is fabricated according to the methods described herein such that the sloped portions of the plurality of structures together constitute at least 5% of the total surface area of ​​the scattering region (as projected onto a plane extending parallel to the ground plane). Applicant has found that sloped portions constituting such a majority of the scattering region's total surface area beneficially impart smaller scattering amplitudes at relatively high scattering angles (e.g., 20° or greater or 30° or greater relative to the specular direction) relative to a scattering region whose sloped portion is a fraction of the total surface area. The approach described herein enables the plurality of structures to be designed to provide a preferred combination of antiglare ("AG") performance attributes. For example, the scattering regions described herein are designed in the spatial frequency domain based on a target radial power spectral density ("PSD") of the article, and the target radial PSD is converted into a phase profile (or "phase map") that is used to form multiple structures via the etching methods described herein. The target radial PSD can be selected to achieve low washout (for the sloped portions described herein) without compromising other desirable AG performance attributes. For example, the articles described herein can achieve a transmission haze of less than 3.5% (or even 3.0% or less, 2.5% or less, 2.0% or less, less than 1.5%, or less than 1.25%), a combined specular reflectance (Rs) of less than 15, and less than 2.5% sparkle (measured at 140 ppi), all while exhibiting low washout (described in more detail herein).

[0045] The plurality of structures of the scattering regions described herein can be formed by a multi-step etching process. An initial etching step (referred to herein as a "basic etching step") is performed using one or more patterned masks (e.g., formed using photolithography or any other suitable process described herein). For example, the patterned mask may cover regions of a first major surface of the article in an array based on a phase mask generated using a target radial PSD. The masked article may then be exposed to a first etchant such that the uncovered regions of the first major surface are etched to a target etching depth. After the basic etching step, the first major surface includes a plurality of first regions positioned at a first average height relative to a ground plane positioned at the etching depth and a plurality of second regions positioned at the ground plane, with a transition surface extending between the first and second regions. The first regions may represent unetched portions of the first major surface, and the second regions may represent etched portions of the first major surface. After the initial etching step is completed, the plurality of structures can be formed by completing a secondary etching step. The secondary etching step can be performed using a dip or spray etching process and includes exposing the entire scattering region to a second etchant that etches the material of the article at an etch rate of at least 0.1 μm / min for a period of at least 1 minute. It has been found that the secondary etching step rounds off any sharp angles present after the initial etching step and converts the transition surfaces into sloped portions of the plurality of structures. The secondary etching step generally reduces the fill fraction associated with the portion of the first major surface located at the initial etch depth relative to the ground plane and increases the percentage of surface area occupied by the sloped portions, providing the reduced washout benefits described herein.

[0046] While alternative techniques exist for creating the sloped portions described herein, such as reducing adhesion between the mask and the article during the initial etching step, as described herein, it has been determined that the multi-step etching manufacturing technique described herein advantageously provides sloped portions with a more uniform shape. Multi-step etching manufacturing techniques are more predictable and repeatable than existing methods, resulting in more consistent optical properties that can be better tailored for various applications. An additional benefit of the multi-step etching process described herein is that the secondary etching step tends to round both the top and bottom corners of the transition surface of the article after the initial etching step. Adhesion control techniques are believed to not round the bottom corners, and articles formed using such techniques tend to have sharp bottom corners, which are believed to be associated with poor washout performance.

[0047] As will be further appreciated in view of the remaining description, the structures described herein can have a variety of different forms and shapes. While the structures described herein can generally be characterized as protrusions extending outward from a ground plane and away from the body of the article, the exact shape of the structures can vary. For example, in embodiments, at least some of the peak portions of the structures located at a peak height are greater than 1 μm, such that the peak portions are planar shaped regions of the first major surface. 2 Additionally or alternatively, at least some of the peak portions may have a smaller surface area (e.g., 0.25 μm or less) such that at least some of the plurality of structures do not include any planar portions disposed at a constant height relative to the ground plane. 2 Regardless of the exact shape of the structures described herein, the presence of the sloped portions is determined to be associated with improved washout performance. In embodiments, the sloped portions may have a slope (in terms of height change relative to the ground plane) of 1.0 or less (e.g., 0.01 or more and 0.3 or less) to provide the optical performance benefits described herein.

[0048] The surface profile of the scattering region described herein is measured on a randomly selected 1 × 1 mm 2 The scattering region can be characterized by generating an Abbott-Firestone ("AF") curve for the region. The AF curve can be generated by measuring the surface height profile of the scattering region with white light interferometry, which provides an azimuthal measurement resolution of 500 nm or less (e.g., 360 nm). Unless otherwise noted, the AF curves included herein are generated using a 50x objective with a 500 nm numerical aperture and a 360 nm lateral resolution per pixel detector. The surface height profile can then be used to generate a histogram of surface height at each pixel of the data set. The histogram can then be integrated to generate the AF curve. An AF curve for a scattering region according to the present disclosure includes a first portion representing the region of the scattering region disposed closest to the ground plane, a second portion representing the peak portion of the plurality of structures, and an intermediate portion extending between the first and second portions. The first and second portions of the AF curve can vary. In embodiments, the AF curve can be characterized as including first and second vertical portions with relatively high slopes (e.g., 350% / μm or greater, including undefined slopes). The intermediate portion may be smaller than the first and second portions and may have a slope of 5% / μm or more. The length of the vertical and intermediate portions may vary depending on the etch depth in the primary etch step and the extent of material removal in the secondary etch steps described herein. Furthermore, the number of vertical and intermediate portions may vary depending on the number of sub-etch steps performed in the primary etch step (e.g., if the first major surface includes features arranged primarily at four heights based on the etch depth used in each sub-etch step, two sub-etch steps may be performed such that the AF curve includes four vertical portions and three intermediate portions). Characterizing the sloped portions in the AF curve can provide an indication of the percentage of surface area occupied by various surface heights. Intermediate portions with slopes within the ranges described herein exhibit a level of feature rounding to provide the improved washout performance described herein.

[0049] A beneficial aspect of the beveled portions described herein is that the articles can exhibit improved wear performance. It is believed that sharp features, such as corners, can break off when the scattering region is abraded by particulate debris, resulting in visible damage. The scattering region of the present disclosure lacks such sharp features, and the beveled portions allow abrasive particles (e.g., dirt, grime, and other debris) to disperse the force when pressed against the first major surface, reducing the likelihood of visible damage. This improved wear performance is particularly beneficial when the article is repeatedly touched by a user (e.g., when the article is used as a protective cover for a touchscreen). Indeed, when articles according to the present disclosure were subjected to the CS8 abrasion test as described herein, the articles exhibited less visible trace damage than comparative articles without rounded features. This demonstrates that the articles described herein exhibit improved durability for touch applications.

[0050] A context in which the articles described herein may be particularly useful is that of vehicle interior displays. A vehicle interior may include one or more displays (e.g., a center console display, a dashboard display, a pillar display, a seatback display, etc.). Such displays may be fixedly oriented relative to the driver. During operation, a vehicle is exposed to ambient light conditions that can cause relatively severe glare. For example, sunlight enters the vehicle interior through the side windows or windshield and reflects or scatters off the displays, creating bright glare that can distract the driver and reduce display performance through washout. The articles described herein can reduce such washout from commonly encountered ambient light conditions. Such favorable washout performance can be achieved while also providing favorable sparkle and transmission haze performance.

[0051] As used herein, the term "target radial PSD" refers to the target radial PSD for a scattering region that is mathematically calculated from the desired far-field scattering pattern of a surface.

[0052] As used herein, "specular reflectance (Rs)" or "Rs" is defined as the peak intensity of light reflected from a first surface of a substrate within a cone of angle ±0.1°. Unless otherwise specified herein, specular reflectance is measured using a Rhopoint IQ meter, which reports Rs values ​​in gross units.

[0053] The articles described herein can be characterized by a distinctness of image value. Terms such as "reflected image distinctness," "image distinctness," and "DOI" are defined by Method A of ASTM Procedure D5767 (ASTM 5767), entitled "Standard Test Methods for Instrumental Measurements of Distinctness-of-Image Gloss of Coating Surfaces." According to Method A of ASTM 5767, glass reflection coefficient measurements are made on at least one roughened surface of a glass article at a specular viewing angle and at a slightly off-specular viewing angle (0.2° to 0.4° away from the specular direction). Such measurements can be made using an orientation measuring instrument (Rhopoint IQ (Goniophotometer) 20° / 60° / 85°, Rhopoint Instruments) calibrated against a certified black glass standard, as specified in ASTM Procedures D523 and D5767.

[0054] As used herein, the terms "haze" or "transmission haze" refer to the percentage of transmitted light scattered outside a cone of approximately ±2.5° according to ASTM D1003, entitled "Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics," the contents of which are incorporated herein in their entirety. Note that although the title of ASTM D1003 refers to plastics, the standard applies to substrates made from glass materials as well. For optically smooth surfaces, transmission haze generally approaches zero.

[0055] As used herein, the terms "sparkle," "sparkle contrast," "display sparkle," "pixel power deviation," "PPD," and similar terms refer to a visual phenomenon that occurs when a textured transparent surface is combined with a pixelated display. Quantifying sparkle generally involves imaging an illuminated or simulated display with the textured surface in a field of view. Calculating sparkle for an area P is equal to σ(P) / μ(P), where σ(P) is the standard deviation of the distribution of integrated intensity for each display pixel contained within area P divided by the mean intensity μ(P). (1) J. Gollier et al., "Apparatus and method for determining sparkle," U.S. Patent No. 941,180 B2, U.S. Patent and Trademark Office, July 20, 2016; (2) A. Stillwell et al., "Perception of Sparkle in Anti-Glare Display Screens," JSID 22(2), pp. 129-136 (2014); and (3) C. Cecala et al., "Fourier Optics Modeling of Display Sparkle from Anti-Glare Cover Glass: Comparison to Experimental Data," Optical Society of America Imaging and Applied Optics Congress, JW5B.8 (2020). Alternatively, commercially available systems (e.g., SMS-1000, Display Messtechnik & Systeme GmbH & Co. Kg, Germany) can be used. Unless otherwise stated, sparkle is measured on a 140 PPI display using the following procedure.A 140 PPI display (e.g., Z50, Lenovo Group Limited, Hong Kong) was imaged using a 50 mm lens / machine vision camera combination (e.g., C220503 1:2.8 50 mm Φ30.5, Tamron, Japan, and Stingray F-125 B, Allied Vision Technologies GmbH, Germany) with only the green subpixel illuminated (R = 0, B = 0, G = 255) and at full display brightness. The lens settings were aperture = 5.6, depth of field = 0.3, and working distance = approximately 290 mm; with these settings, the display pixel to camera pixel ratio was approximately 1:9. The field of view for analysis included approximately 7500 display pixels. Gain and gamma correction were turned off in the camera settings. For example, periodic intensity variations from the display and non-periodic intensity variations, such as dead pixels, were removed during analysis before calculating sparkle.

[0056] Antiglare performance can be measured with nothing bonded to the surface (referred to herein as "unbonded") or with a black absorber bonded to the backside of the glass (referred to herein as "bonded").

[0057] 1 , an example embodiment of article 10 is shown. Article 10 includes a substrate 12. In the illustrated embodiment, article 10 is a display article (e.g., a display cover article) and further includes a housing 14 to which substrate 12 is coupled and a display 16 within housing 14. In such an embodiment, substrate 12 at least partially covers display 16 such that light emitted by display 16 can be transmitted through substrate 12.

[0058] Substrate 12 can be a variety of materials depending on the implementation. For example, in embodiments such as the embodiment shown in FIG. 1, substrate 12 is a glass or glass-ceramic substrate. Various properties and examples of such glass or glass-ceramic substrates are described in more detail herein. In embodiments, substrate 12 may be made of materials other than glass, such as paper, plastic, or other suitable polymeric materials. In embodiments, substrate 12 can include a combination of glass and polymeric materials. In one example, the scattering region 20 described herein is formed in a layer of polymeric material formed on a glass substrate. In embodiments, substrate 12 is transparent or exhibits an average transmittance of 70% or more (e.g., 80% or more, 85% or more, 90% or more, 92% or more, 92.5% or more, 93% or more) for light normally incident on substrate 12 in the wavelength range of 400 nm to 700 nm. In embodiments, substrate 12 is opaque or exhibits an average transmittance of 30% or less for light normally incident on substrate 12 in the wavelength range of 400 nm to 700 nm. In an embodiment, substrate 12 is colored to exhibit a colored appearance under ambient lighting (eg, from sunlight).

[0059] Substrate 12 has a first major surface 18, a second major surface 19, a scattering region 20 defined on first major surface 18, and a thickness 21 (e.g., representing the smallest distance between first major surface 18 and second major surface 19 at a particular point on first major surface 18) that is bounded in part by first major surface 18. In the illustrated embodiment, substrate 12 is substantially planar in shape, such that first major surface 18 and second major surface 19 are generally flat (except for a plurality of surface features formed on first major surface 18 at scattering region 20, as described herein). Embodiments in which substrate 12 includes curved shapes (e.g., by suitable hot-forming and cold-forming techniques) are also contemplated and within the scope of the present disclosure. In such embodiments, references herein to a "surface normal" (shown as surface normal 33 in FIG. 1) refer to the local surface normal at the point where light from external environment 24 enters first major surface 18. In the illustrated embodiment, first major surface 18 generally faces an external environment 24 surrounding article 10 and faces away from display 16. In the embodiment, display 16 emits visible light that passes through thickness 21 of substrate 12, exits first major surface 18, and enters external environment 24.

[0060] As shown in FIG. 1, light from an external environment 24, represented by incident ray 22, is incident at an angle of incidence θ i (Incident light ray 22 may be incident on first major surface 18 at a zenith angle θ (representing an angle extending relative to a surface normal 33 of first major surface 18, shown as the z-direction in FIG. 1 ). Incident light ray 22 can represent light from many different sources external to article 10. For example, incident light ray 22 can represent sunlight incident on first major surface 18, or light from another external source (e.g., light reflected or scattered by an external object, light produced by another light source). Scattering region 20 scatters light, represented by incident light ray 22, in a scattering direction, represented by scattered light ray 25. The light is incident at an angle of incidence θ relative to surface normal 33. i and scattering angle θ s As shown, scattered light ray 25, when projected onto the plane of first major surface 18 extending perpendicular to surface normal 33, is scattered in a scattering direction that extends at an azimuthal angle Φ with respect to the first direction (the x-direction shown in FIG. 1).

[0061] In an embodiment, scattering region 20 is designed based on a target radial PSD. The target radial PSD can be azimuthally averaged with respect to azimuth angle Φ so that the PSD is statistically isotropic with respect to azimuth angle. The target radial PSD varies with zenith angle θ according to the same functional relationship, regardless of azimuth angle Φ. s Such a target radial PSD beneficially minimizes the effect of rotational orientation of article 10 in external environment 24 on AG performance.

[0062] 2 is a schematic illustration of a plan view of region II of scattering region 20 of article 10 shown in FIG. 1 , in accordance with an exemplary embodiment of the present disclosure. As shown, scattering region 20 includes a plurality of structures 26. Structures 26 generally vary in size and perimeter shape, and have longitudinal axes extending in a plurality of different directions in a plane parallel to ground plane 30 (see FIG. 3A ). However, the randomness in the arrangement of structures 26 differs from the randomness in certain existing AG surfaces (e.g., caused by sandblasting) in that the arrangement of structures 26 is reproducible (within manufacturing tolerances) by the methods described herein.

[0063] In embodiments, the plurality of structures 26 are designed based on a target radial PSD in the Fourier domain, as described herein. In embodiments, the plurality of structures 26 include features that protrude outward from a ground plane defined by portions of the first major surface 18. For example, FIG. 3A illustrates a cross-sectional view of the scattering region 20 shown in FIG. 2. As shown, the article 10 includes a ground plane 30 that represents the portion of the first major surface 18 disposed closest to the second major surface 19. The ground plane 30 generally represents the portion of the first major surface 18 that contacts one or more first etchants of the basic etching processes described herein. That is, the ground plane 30 represents the area of ​​the substrate 20 from which most of the material has been removed during the basic etching process. For example, the basic etching process may include only one sub-etching process; in such embodiments, the ground plane 30 may represent the area of ​​the first major surface 18 that was not covered by an etch mask during the basic etching process.

[0064] In embodiments, the base etch process can be controlled so that the plurality of first portions 32 of the first major surface 18 are substantially planar and located within the ground plane 30 (or within a tolerance of less than 1% of the etch depth described herein from the ground plane 30). For example, in embodiments, the surface height variation (or roughness) may be less than 50 nm (or less than 20 nm RMS, or less than 10 nm RMS) in terms of root mean square (RMS) variation within a particular one of the plurality of first portions 32. For example, in these embodiments, each of the plurality of first portions 32 of the first major surface 18 can be characterized by a surface height variation of 0.1 nm RMS to 50 nm RMS, 0.1 nm RMS to 20 nm RMS, 0.1 nm RMS to 10 nm RMS, or 0.1 nm RMS to 1 nm RMS. In some embodiments, the peak portions 42 can exhibit similar surface roughness characteristics (e.g., when not perfectly rounded).

[0065] As shown in FIG. 3A , the plurality of structures 26 generally includes a protrusion of the first major surface 18 extending outward from the ground plane 30, away from the second major surface 19. Each of the plurality of structures 26 may have a different shape (e.g., different perimeter shapes) and / or a different number of substructures. In the example shown in FIG. 3A , the first structure 26 a includes a support pillar protruding from the ground plane 30 and does not include any intermediate substructures. In contrast to the first structure 26 a, the second structure 26 b includes a substructure in which the curvature or surface shape of the first major surface 18 changes abruptly in areas other than the outer boundary or peak portion of the structure, as described herein. In the illustrated example, the second structure 26 b includes a first substructure 36 and a second substructure 38, which are substantially planar portions of the first major surface 18 positioned at different heights h2 and h3 relative to the ground plane 30. Such substructures may result from multiple sub-etching steps within the basic etching step described herein.

[0066] In an embodiment, the first major surface 18 includes multiple distinct regions disposed at different heights relative to the ground plane 30. The surface height profile of the scattering region 20 can form a multimodal height distribution relative to the ground plane 30, where the number of modes is determined, in some cases, based on the number of sub-etching steps performed in the basic etching process described herein or the extent of material removal during secondary etching steps. Each mode of the multimodal height distribution can be characterized by a distinct peak in a histogram of surface height occurrences created from the surface height profile obtained from the white light interferometry measurement. In an example where the basic etching process includes only one sub-etching step, the surface height profile of the scattering region 20 can form a bimodal height distribution, where the histogram includes two distinct peaks: one associated with the multiple first portions 32 disposed on the ground plane 30 and one associated with the multiple second portions 34 disposed at a first height h1 relative to the ground plane 30. The multiple second portions 34 can represent portions of the first major surface 18 that are not etched during the basic etching process described herein. As a result, h1 can correspond to the etch depth selected for the basic etching process. In examples where the base etch step includes multiple sub-etch steps, the surface height profile of scattering region 20 may form a multimodal height distribution having at least three modes, or at least three distinct peaks in a histogram (the secondary etch steps described herein may provide multiple intermediate peaks that are indistinguishable from one another). In such embodiments having multiple sub-etch steps, h1 may represent a summary of the etch depth associated with each of the individual sub-etch steps in the base etch step described herein.

[0067] Each of the plurality of structures 26 (or substructures therein) includes a sloped portion 40 and a peak portion 42 disposed at a peak height associated with that structure (or substructure). In the sloped portion 40, the surface height of the first major surface 18 increases with increasing lateral distance away from the nearest one of the plurality of first portions 32. The average slope of the first major surface 18 within the sloped portion 40 will be greater than the average slope within the plurality of first portions 32. Within the sloped portion 40, the first major surface 18 may have a slope ranging from 0.01 to 0.1 or less as a function of lateral position in a direction perpendicular to the surface normal of the sloped portion 40. In embodiments, for example, the sloped portion 40 includes a region of the first major surface 18 in which the surface height, measured in a direction extending perpendicular to the sloped portion 40, varies by more than 10 nm per μm of linear distance and less than 100 nm per μm of linear distance, where the linear distance is measured in a plane parallel to the ground plane 30. As a result of the slope of the angled portion 40, there are no sharp features (eg, corners) on the first major surface 18, which helps to reduce scattering amplitude at relatively high scattering angles.

[0068] The peak portions associated with each of the plurality of structures 26 (and associated substructures) may vary in shape. In the illustrated embodiment, for example, peak portion 42 is a substantially planar portion disposed at a height h1 relative to the ground plane 30. In alternative embodiments, at least some (if not all) of the plurality of structures 26 do not include any planar portions (the tops of the structures may be completely rounded as a result of the secondary etching process described herein), such that peak portion 42 constitutes a point on a substructure disposed at the peak height. In addition, the peak heights of adjacent ones of the plurality of structures 26 need not be identical to one another. For example, as shown in FIG. 3A , second structure 26b includes a first peak region 42a disposed at a height h3 relative to the ground plane 30, a second peak height 42b disposed at a height h1 relative to the ground plane 30, and a third peak region 42c disposed at a height h2 relative to the ground plane 30. The arrangement of the surface heights of the peak portions 42 is generally determined by the pattern associated with one or more etching masks used in the basic etching process described herein.

[0069] It has been found that the excellent washout and mechanical wear performance described herein can be provided when the sloped portions 40 of the plurality of structures 26 occupy at least 5% (or even at least 10%, or even at least 15%, or even at least 20%, or even at least 30%, or even at least 40%, or even at least 50%) of the total surface area of ​​the scattering region 20 (as projected onto the ground plane 30). That is, when the scattering region 20 is viewed facing the first major surface 18 in a direction perpendicular to the ground plane 30, the sloped portions 40 occupy at least 5% of the total surface area of ​​the scattering region 20. The uniformity (e.g., in terms of slope and transition width) of the sloped portions described herein, provided by the multi-step etching process described herein, can help achieve this area percentage and ensure uniform washout reduction regardless of the particular location within the scattering region 20.

[0070] The sloped portions 40 may also be characterized by a lateral transition width w along which the first major surface 18 transitions between modes of a multimodal height distribution associated with the surface height profile of the scattering region 20. Referring to FIG. 3B, in embodiments, each of the sloped portions 40 includes a first edge 43 located proximate to the peak portion 42 and a second edge 44 (e.g., one of the plurality of first portions 32) located adjacent to a lower surface height feature. As shown in FIG. 3B, the sloped portions 40 may have a width w. The width w is measured as the lateral distance between the first edge 43 and the second edge 44 in a plane parallel to the ground plane 30 (the x-y plane shown in FIGS. 1-2). The lateral distance is also measured in a direction extending parallel to the projection of the surface normal 46 of the sloped portion 40 onto the x-y plane. In embodiments, width w is 1.0 μm or more and 10.0 μm or less (e.g., 1.0 μm or more and 9.0 μm or less, 1.0 μm or more and 8.0 μm or less, 1.0 μm or more and 7.0 μm or less, 1.0 μm or more and 6.0 μm or less, 1.5 μm or more and 6.0 μm or less, 2.0 μm or more and 6.0 μm or less, 3.0 μm or more and 10 μm or less). A width within such a range indicates a lack of sharpness in the transition of the slope of first major surface 18. First major surface 18 has a gradual transition between the slopes (e.g., rounded corners) rather than relatively sharp corners at first and second edges 43 and 44. As described in more detail herein, rounding such features helps reduce high spatial frequency content in the radial PSD of scattering region 20, thereby providing favorable washout performance. Unless otherwise specified, width w is the maximum measurement of the lateral distance across a particular transition surface.

[0071] The width w can be measured by a variety of different techniques. For example, the width w can be physically measured by creating a line profile of the first major surface 18. The line profile can be created by measuring the surface height of the first major surface 18 using white light interferometry. The line profile can also be obtained by other known methods (e.g., using a scanning electron microscope, an atomic force microscope, or a stylus profiler). The image is sampled in a direction extending perpendicular to the sloped portion 40 at the point where the width w is being measured (extending parallel to the projection of the surface normal 46 onto the xy plane, where the surface normal is located at the first edge 43). The width w at a particular point on the sloped portion 40 is calculated as the smallest lateral distance between points located at heights that differ from each other by no more than 10% of the difference between heights associated with adjacent peaks in the multimodal height distribution. The particular modality used to image the first major surface 18 in measuring the width w can vary depending on the size of the width w. If the width is less than 2.0 μm, an atomic force microscope can be used to image the first major surface 18. If the width w is 2.0 μm or greater, line profiles can be extracted from white light interferometry data as described herein. The resulting width w can be measured as the smallest lateral distance between points located at heights that differ from each other by no more than 10% of the difference between adjacent heights in a multimodal height distribution.

[0072] Referring again to Figure 3A, the physical structure of the plurality of structures 26 can be determined using Fourier analysis of diffraction. As shown in Figure 3A, incident radiation from the external environment 24 is

[0073]

number

[0074] can be approximated as a uniform plane wave expressed as o represents the uniform intensity of the incident radiation, and k xo and k yorepresents the wave vector components related to the wavelength and angle of incidence (e.g., the angle of incidence can be separated into components in the xz and yz planes shown in FIG. 1) of the incident ray on first major surface 18. In such a case, the scalar near field for the outgoing ray (after interaction with first major surface 18) is

[0075]

number

[0076] where ρ is the Fresnel coefficient of the interface, TIFF2026500458000004.tif9114

[0077] is the local phase accumulated over two passes through the distance to the first major surface 18, and H(x,y) represents the pattern formed by the plurality of structures 26. In this example, the incident ray is approximated as having a uniform intensity distribution, and the interface between the substrate 12 and the external environment 24 is approximated as applying only a spatially varying phase such that the near-field exiting ray also has a uniform intensity distribution.

[0078] In this example shown in FIG. 3A, the far-field scattering pattern associated with the outgoing ray can be expressed in spatial frequency (k) space and the near-field u can be calculated by Fourier transform using Equation 3: near Associated with (x,y),

[0079]

number

[0080] where k x and k y represents the scattering vector component (k x =|k| * cos(Φ), k y =|k| * sin(Φ)), where k is

[0081]

number

[0082] where Φ is the azimuthal angle shown in FIG. 3 and λ is the wavelength of the scattered radiation. As used herein, the "PSD" of scattering region 20 is defined as:

[0083]

number

[0084] where A is the area of ​​scattering region 20. As used herein, the term "target radial PSD" refers to Equation 5 when averaged over the full range of azimuth angles Φ. The target radial PSD is given by the following equation:

[0085]

number

[0086] using the azimuthally averaged PSD ( <psd> Φ ) Therefore, the target radial PSD depends only on the magnitude of the spatial frequency and wavelength of the scattered radiation. Unless otherwise specified, the radial PSD is expressed assuming a wavelength of 550 nm. The term "target radial PSD" refers to the result calculated from Equation 6. In an embodiment, the plurality of structures 26 are constructed such that H(x,y), when input into Equation 2, substantially matches the target radial PSD. An example set of target radial PSDs that can be used to design the scattering region 20 are:

[0087]

number

[0088] where α is the exponential decay parameter and k max is the non-zero scattering angle θ at which the target radial PSD is equal to zero max is the spatial frequency associated with k peak is the peak angle θ at which the target radial PSD has a peak value peak is the spatial frequency related to the wavelength of 550 nm. max , and θ peak Different values ​​for can be used to generate target radial PSDs that provide different performance attributes. Guidance on parameter selection for particular combinations of performance attributes can be found in U.S. Provisional Patent Application No. 63 / 420222, filed October 28, 2022, which is incorporated herein by reference in its entirety.

[0089] Once a suitable target radial PSD has been identified, the target radial PSD can be used to calculate a phase distribution for the first major surface 18 using the methods described herein. TIFF2026500458000010.tif8114

[0090] can be determined. For example, a phase map can be created using an inverse Fourier transform of the target radial PSD. Such techniques can generally produce complex-valued phase maps that are non-biphasic (and therefore not consistent with a surface having a bimodal height distribution, such as that shown in FIG. 3). Non-biphasic phases are problematic in that certain existing manufacturing processes, such as the etching methods described herein, are unable to produce such structures. Therefore, a threshold can be applied to the phase map so that discrete regions ("pixels") of the phase map form a discrete distribution of phases. The imaginary terms of the created phases can be discarded, and a threshold can be applied to the real values ​​so that pixels with a mean value below the threshold are assigned a first phase (e.g., π / 2) and pixels with a mean value above the threshold are assigned a second phase (e.g., -π / 2). In embodiments, the threshold value is selected so that an equal number of pixels are calculated to have the first and second phases (e.g., each phase occupies 50% of the surface area of ​​the scattering region). The pixel size can be selected based on the estimated minimum feature size achievable by the etching processes described herein. In an embodiment, the pixel size is 20 nm or more (eg, 300 nm or more, 400 nm or more, 500 nm or more, 600 nm or more, 700 nm or more, 800 nm or more, 900 nm or more, 1000 nm or more).

[0091] FIG. 4 illustrates a flow diagram of an example method 400 for manufacturing an article 10 according to an example embodiment of the present disclosure. The various components and processes illustrated in FIGS. 1-3B are referenced to assist in explaining the method 400. The method used to form the article 10 is not particularly limited, and any suitable method may be used. In block 402, a pattern of the plurality of structures 26 is determined. In an embodiment, the pattern is determined by the techniques described herein with respect to FIGS. 3A-3B, i.e., by selecting a target radial PSD, creating a phase map based on the target radial PSD, and thresholding the created phase map.

[0092] In block 404, one or more etch masks are placed on the substrate 12, and a basic etching process is performed using one or more etchants to form sharp features in the scattering region based on the pattern determined in block 402. For example, resist is deposited and patterned on the first major surface 18 to form a first of the one or more etch masks. The nature of the resist deposition and patterning will vary depending on the fabrication technique used. In embodiments, various nanoimprint or photolithography techniques can be used to deposit and pattern the resist layer. In such embodiments, to facilitate the use of existing resist application and patterning techniques, the minimum feature size (e.g., minimum line dimension) associated with the plurality of structures 26 can be set to at least 400 nm (e.g., 500 nm or greater, 600 nm or greater, 700 nm or greater, 800 nm or greater, 900 nm or greater, 1.0 μm or greater, 1.5 μm or greater, 2.0 μm or greater, 2.5 μm or greater, 5.0 μm or greater). In embodiments, for example, the resist may be formed using thermoplastic nanoimprint lithography, where the resist is formed from a thermoplastic polymer that is spin coated onto substrate 12 and then imprinted with a mold to form a first pattern that at least partially corresponds to the pattern of the plurality of structures 26 on first major surface 18. The resist may then be thermally cured to form an etch mask. Other methods of forming the resist (e.g., gravure offset printing, other printing techniques) are also contemplated and within the scope of the present disclosure.

[0093] Photolithography (e.g., photoimprint nanolithography, optical photolithography) techniques can also be used, and a resist can be deposited on first major surface 18 by a suitable application method (e.g., spin coating). In such embodiments, a mask comprising a first pattern corresponding at least in part to the pattern determined for plurality of structures 26 can be aligned with first major surface 18, and the resist can be exposed to radiation (e.g., ultraviolet light) from a suitable light source to harden the resist and form an etch mask. The resist can then be developed so that portions of first major surface 18 remain exposed through the hardened resist. Any suitable photolithography technique can be used to pattern the resist.

[0094] After the resist is patterned, in a basic etching process, exposed areas of first major surface 18 (through the hardened, patterned resist) are exposed to an appropriate etchant for an appropriate etching period determined based on the target etch depth. Each area of ​​first major surface 18 exposed through the patterned resist can be directly contacted with the etchant, thereby decomposing substrate 12 and removing material therefrom. In an embodiment, the etchant contacting first major surface 18 is an HF / HNO etchant. In an embodiment, the etchant comprises a combination of hydrofluoric acid (HF, 49% w / w) and nitric acid (HNO 3, 69% w / w), with 0.1-5% v / v HF and 0.1-5% v / v HNO 3 . Typical concentrations used to achieve the etch depths described herein are solutions of 0.1% v / v HF / 1% v / v HNO 3 to 0.5% v / v HF / 1% v / v HNO 3 . In embodiments, etching can be performed at room temperature to 45°C using a dip or spray etching process.

[0095] The basic etching step can include any suitable number of sub-etching steps, each involving exposing a different area of ​​first major surface 18 to an etchant through a separate mask. For example, the basic etching step can include two sub-etching steps, in which a first etch mask is deposited and patterned on first major surface 18 and a first set of areas is exposed to an etchant to etch the first areas to a first etch depth. After removal of the first etch mask, a second etch mask can be deposited and patterned on first major surface 18 to facilitate exposing a second area of ​​first major surface 18 to an etchant to etch the second area to a second etch depth relative to the height achieved after the first sub-etching step. The pattern of the second etch mask can be determined in a similar manner to the first etch mask. For example, in embodiments, the same target radial PSD can be used to create the second etch pattern as used in the first etch step. However, when the resist is disposed on the first major surface 18, the substrate 12 can be rotated by an angle (e.g., 90°, 180°, or any other angle) so that the pattern is applied to the first major surface 18 in a different orientation in the second etch compared to the first etch. Alternatively, a different target radial PSD can be used to create a pattern for the second etch that is not used for the first etch.

[0096] The first and second areas exposed to the etchant in the first and second sub-etch steps can be arranged such that the first and second sub-etch steps result in a surface height profile having a four-modal distribution (having four distinct surface height peaks in terms of frequency of occurrence in a histogram generated from white light interferometry data). Embodiments are contemplated in which three or more sub-etch steps are performed to provide an even greater number of modes. It has been found that providing at least four modes in the surface height profile can provide certain performance improvements over a single sub-etch step design, such as improved specular reflectance reduction and reduced DOI. Multilevel design allows for coherent suppression of specular reflection over a wide range of optical wavelengths. The performance attributes of multilevel designs are described in more detail herein with reference to examples.

[0097] The base etching step at block 404 is generally performed to form sharp features in the scattering region. By "sharp," we mean that the areas exposed to the etchant during the etching step are uniformly removed to create a multilevel surface structure including a plurality of substantially planar regions disposed at different heights relative to the ground plane 30 (adjacent heights may differ from one another by 20 nm to 200 nm in a direction perpendicular to the ground plane 30), with the transition surfaces extending between each of the levels extending substantially perpendicular to the ground plane 30 (i.e., so that there are no sloped portions 40 in the first major surface 18). Such sharpness is generally achieved by promoting adhesion between the resist and the substrate 12 to prevent undercutting of the resist during the base etching step. In embodiments, an adhesion promoter (e.g., hexamethyldisilazane (HDMS) or N,N-dimethyl-N-(3-(trimethoxysilyl)propyl)octadecane-1-ammonium chloride, YSAM C18) is applied to the first major surface 18 before the resist is applied. In embodiments, any of the adhesion promoters described in U.S. Patent No. 9,884,782, filed April 1, 2015, and incorporated herein by reference in its entirety, can be applied to the glass prior to the deposition of resist in the basic etching process. Such adhesion promoters generally exhibit dual adhesion or attractive functionality, with one portion of the promoter being attracted to the substrate 12 and another portion being attracted to the photoresist material. For certain articles described herein, it has been found that providing an adhesion promoter on the first major surface 18 that exhibits a water contact angle (after deposition) of 65° or greater (before deposition of the mask or other masking material) should provide sufficiently sharp features. The water contact angle that exhibits sharp features can vary depending on the adhesion promoter used. For example, a water contact angle of at least 75° (e.g., at least 80°) has been found to be sufficient when using HDMS as the adhesion promoter, while a water contact angle of at least 90° has been found to be sufficient when using YSAM C18. Any other method capable of providing sharp features without significant feature rounding can be used.Such sharpness indicates high adhesion between the resist and substrate 12, which allows for precise control over the shape of features formed on first major surface 18 during the basic etching process, and therefore control over the optical performance of scattering region 20.

[0098] Still referring to FIG. 4 , after the basic etching step is completed, a secondary etching step is performed in block 406 by applying a secondary etchant to the scattering region 20 to round off sharp features and form a plurality of structures. In the secondary etching step, the entire scattering region 20 can be directly bonded to the secondary etchant after removing the mask used in the basic etching step. Such a secondary etching step has been found to round off sharp features (e.g., corners) of the article 10 and provide the improved washout performance described herein. The secondary etching step can be performed using any suitable etching process, such as a dipping process or a spraying process. For example, in a dipping process, the article can be immersed in a secondary etchant having a concentration ratio of HF to HCl ranging from 0.5M HF / 0.5M HCl to 3M HF / 3M HCl, such that the etch rate of the article is greater than 0.1 μm / min or greater than 0.5 μm / min. In such embodiments, the article can be exposed to the secondary etchant for a period of at least 1 minute (e.g., 1 minute to 30 minutes, 1 minute to 20 minutes, 5 minutes to 20 minutes). In a spraying process, the article 10 can be sprayed with a secondary etchant having a concentration ratio of HF to HCl of 16 mM HF / 20 mM HCl to 160 mM HF / 200 mM HCl to achieve an etch rate of 0.1 μm / min to 1 μm / min for a period of at least 1 minute (e.g., 1 minute to 30 minutes, 1 minute to 20 minutes, 5 minutes to 20 minutes). Such periods and concentrations have been found to provide an appropriate amount of feature rounding for improved washout performance.

[0099] Without intending to be bound by theory, it is believed that the secondary etching process results in feature rounding due to variable etch rates in various regions of the sharp features formed in block 404. Based on computational fluid dynamics modeling, it is believed that convex corners (e.g., first edge 43 shown in FIG. 3B ) experience faster etch rates than flat regions of first major surface 18 (e.g., first portions 32) because the convex corners have the largest area per unit volume exposed to the secondary etchant and therefore a larger area over which the etching reaction occurs. Furthermore, the exposed structures of the convex corners are better supplied with reactants, maintaining a higher acid concentration in those regions. In contrast, re-entrant corners (e.g., second edge 44 shown in FIG. 3B ) have a relatively small surface area per unit volume, resulting in a limited supply of reactants and therefore a lower etch rate. It is believed that flat surfaces, despite having a relatively low surface area-to-volume ratio, exhibit intermediate etch rates (between convex and re-entrant corners) due to improved reactant supply in open spaces (relative to re-entrant corners).

[0100] An alternative method for providing rounded features is to forgo the secondary etching step at block 406 and instead reduce adhesion between the resist and substrate 12 during the base etching step performed in block 404. For example, modifying the surface chemistry (with respect to hydrophobic groups) of the adhesion promoters described herein can provide some control over undercutting during etching and feature rounding. Additionally or alternatively, the amount of adhesion promoter applied to the surface can also affect the amount of adhesion. Adhesion promoter can also be removed from first major surface 18 before applying resist thereto to modify the adhesion of the resist. Applicant has found that modifying the water contact angle of first major surface 18 prior to masking can modify adhesion with the resist and therefore affect the amount of feature rounding. For example, it has been found that depositing an adhesion promoter on first major surface 18 that exhibits a water contact angle (after deposition) of 40° or greater and 65° or less (e.g., 45° or greater and 60° or less, 48° or greater and 52° or less) provides an appropriate amount of feature rounding (e.g., with respect to feature transition widths and AF curves with appropriately sloped mid-portions).

[0101] The secondary etching process described herein is believed to provide surface structures with shapes different from those imparted by alternative methods of adhesion control during the basic etching process. Figures 5A, 5B, and 5C show 2D surface height profiles (i.e., line profiles created from white light interferometry data representing cross sections of substrate 12 taken in a direction perpendicular to ground plane 30) for various samples. Figure 5A shows a sample after undergoing the basic etching process described herein in which adhesion between the substrate and resist was strong (the substrate exhibited a water contact angle of greater than 70° before masking). Figure 5B shows a sample after undergoing the basic etching process in which the adhesion promoter chemistry was modified to reduce adhesion between the substrate and resist and promote undercutting (the substrate exhibited a water contact angle of less than 65° after the adhesion promoter was deposited). Figure 5C shows a sample after undergoing both the basic and secondary etching processes described herein with respect to Figure 4. In the example shown in FIG. 5A, the illustrated surface includes a first region 502 defining a ground plane and a second region 504 disposed at a peak height relative to the ground plane that is just less than 200 nm high. A transition surface 506 separates the first and second regions 502 and 504. As shown, the transition surface 506 defines a transition width w (see FIG. 3B) of less than 1 μm. Furthermore, the defined features have relatively sharp corners. In the example shown in FIG. 5B, the illustrated surface includes a first region 508 defining a ground plane and a plurality of second regions 510 disposed at a peak height relative to the ground plane that is just less than 150 nm high. A transition surface 512 separates the first and second regions 508 and 510. However, the transition surface 512 defines a transition width w of more than 1 μm, in contrast to the sample shown in FIG. 5A. Furthermore, the convex corner 514 is rounded, indicating some degree of undercutting. However, the re-entrant corner 516 is relatively free from the effects of undercutting, and therefore the surface still exhibits an abrupt change in slope at the re-entrant corner 516 .

[0102] In the example shown in FIG. 5C , the illustrated surface includes a first region 518 defining a ground plane and a plurality of second regions 520 disposed at peak heights between 150 nm and 200 nm relative to the ground plane. A transition surface 522 separates the first and second regions 518 and 520. The transition surface 522 defines a transition width w of greater than 1 μm. However, the convex and concave corners 524 and 526 are rounded, in contrast to the sample shown in FIG. 5B . Thus, the example shown in FIG. 5C exhibits a less abrupt transition in the surface gradient than the example shown in FIG. 5B . Such elimination of high spatial frequency features is believed to be associated with reduced scattering amplitude at high scattering angles (i.e., superior washout performance). Furthermore, as described in more detail, such gradual surface transitions are believed to be associated with superior wear performance.

[0103] Substrate properties Various properties of substrate 12 according to embodiments of the present disclosure will now be described.

[0104] In embodiments, substrate 12 is a glass substrate or a glass-ceramic substrate. In embodiments, substrate 12 is a multi-component glass composition having about 40 mol % to 80 mol % silica and the remaining amount of one or more other components, such as alumina, calcium oxide, sodium oxide, boron oxide, etc. In some implementations, the bulk composition of substrate 12 is selected from the group consisting of aluminosilicate glass, borosilicate glass, and phosphosilicate glass. In other implementations, the bulk composition of substrate 12 is selected from the group consisting of aluminosilicate glass, borosilicate glass, phosphosilicate glass, soda-lime glass, alkali aluminosilicate glass, and alkali aluminoborosilicate glass. In further implementations, substrate 12 is a glass-based substrate, including, but not limited to, a glass-ceramic material containing about 90% or more by weight of glass and ceramic components. In other implementations of article 10, substrate 12 can be a polymeric material having durability and mechanical properties suitable for generating and maintaining scattering regions 20.

[0105] In embodiments, substrate 12 has a bulk composition constituting an alkali aluminosilicate glass comprising alumina, at least one alkali metal, and in some embodiments greater than 50 mol% SiO, in other embodiments at least 58 mol% SiO, and in still other embodiments at least 60 mol% SiO, with the ratio (AlO (mol%) + BO (mol%)) / ΣAlkali Metal Modifier (mol%) > 1, where the modifier is an alkali metal oxide. The glass, in particular embodiments, comprises, consists essentially of, or consists of about 58 mol% to about 72 mol% SiO, about 9 mol% to about 17 mol% AlO, about 2 mol% to about 12 mol% BO, about 8 mol% to about 16 mol% NaO, and 0 mol% to about 4 mol% KO, and has a ratio (AlO(mol%)+BO(mol%)) / ΣAlkali Metal Modifier(mol%)>1, where the modifier is an alkali metal oxide.

[0106] In an embodiment, substrate 12 has a bulk composition comprising an alkali aluminosilicate glass comprising, consisting essentially of, or consisting of about 61 mol% to about 75 mol% SiO, about 7 mol% to about 15 mol% AlO, 0 mol% to about 12 mol% BO, about 9 mol% to about 21 mol% NaO, 0 mol% to about 4 mol% KO, 0 mol% to about 7 mol% MgO, and 0 mol% to about 3 mol% CaO.

[0107] In an embodiment, the substrate 12 comprises about 60 mol% to about 70 mol% SiO, about 6 mol% to about 14 mol% AlO, 0 mol% to about 15 mol% BO, 0 mol% to about 15 mol% LiO, 0 mol% to about 20 mol% NaO, 0 mol% to about 10 mol% KO, 0 mol% to about 8 mol% MgO, 0 mol% to about 10 mol% CaO, 0 mol% to about 5 mol% SiO, and 0 mol% to about 15 mol% BO. The bulk composition constituting an alkali aluminosilicate glass comprises, consists essentially of, or consists of ZrO2, 0 mol% to about 1 mol% SnO2, 0 mol% to about 1 mol% CeO2, less than about 50 ppm As2O3, and less than about 50 ppm Sb2O3, and wherein 12 mol%≦Li2O+Na2O+K2O≦20 mol%, and 0 mol%≦MgO+Ca≦10 mol%.

[0108] In embodiments, substrate 12 comprises, consists essentially of, or consists of about 64 mol% to about 68 mol% SiO, about 12 mol% to about 16 mol% NaO, about 8 mol% to about 12 mol% AlO, 0 mol% to about 3 mol% BO, about 2 mol% to about 5 mol% KO, about 4 mol% to about 6 mol% MgO, and 0 mol% to about 5 mol% CaO, with 66 mol%≦SiO+ The bulk composition constituting an alkali aluminosilicate glass is B2O3 + CaO ≦ 69 mol%, Na2O + K2O + B2O3 + MgO + CaO + SrO > 10 mol%, 5 mol% ≦ MgO + CaO + SrO ≦ 8 mol%, (Na2O + B2O3)-Al2O3 ≦ 2 mol%, 2 mol% ≦ Na2O-Al2O3 ≦ 6 mol%, and 4 mol% ≦ (Na2O + K2O)-Al2O3 ≦ 10 mol%.

[0109] In embodiments, substrate 12 has a bulk composition including SiO, AlO, PO, and at least one alkali metal oxide (RO), where 0.75 > [(PO (mol%) + RO (mol%)) / MO] < 1.2, where MO = AlO + BO. In embodiments, [(PO (mol%) + RO (mol%)) / MO] = 1, and in embodiments, the glass is B0-free, where MO = AlO. In embodiments, substrate 12 includes about 40 to about 70 mol% SiO, 0 to about 28 mol% BO, about 0 to about 28 mol% AO, about 1 to about 14 mol% PO, and about 12 to about 16 mol% RO. In some embodiments, the glass substrate comprises about 40 to about 64 mol% SiO, 0 to about 8 mol% B O, about 16 to about 28 mol% Al O, about 2 to about 12 mol% P O, and about 12 to about 16 mol% R O. The substrate 12 may further comprise at least one alkaline earth metal oxide, such as, but not limited to, MgO or CaO.

[0110] In some embodiments, substrate 12 has a bulk composition that is substantially free of lithium, i.e., the glass contains less than 1 mol% Li2O, in other embodiments less than 0.1 mol% Li2O, in other embodiments 0.01 mol% Li2O, and in still other embodiments 0 mol% Li2O. In some embodiments, such glasses are free of at least one of arsenic, antimony, and barium, i.e., the glass contains less than 1 mol%, in other embodiments less than 0.1 mol%, and in still other embodiments 0 mol% As2O3, Sb2O3, and / or BaO.

[0111] In embodiments, substrate 12 has a bulk composition comprising, consisting essentially of, or consisting of a glass composition such as Corning® Eagle XG® Glass, Corning® Gorilla® Glass, Corning® Gorilla® Glass, Corning® Gorilla® Glass 2, Corning® Gorilla® Glass 3, Corning® Gorilla® Glass 4, or Corning® Gorilla® Glass 5.

[0112] In embodiments, substrate 12 has an ion-exchangeable glass composition that can be strengthened by any chemical or thermal means known in the art. In embodiments, substrate 12 is chemically strengthened by ion exchange, during which metal ions at or near first major surface 18 of substrate 12 are exchanged for larger metal ions having the same valence as the metal ions in the glass substrate. The exchange is generally accomplished by contacting substrate 12 with an ion exchange medium, such as, for example, a molten salt bath containing the larger metal ions. The metal ions are typically monovalent metal ions, such as, for example, alkali metal ions. In one non-limiting example, chemical strengthening by ion exchange of substrate 12 containing sodium ions is accomplished by immersing substrate 12 in an ion exchange bath containing a molten potassium salt, such as potassium nitrate (KNO). In one particular embodiment, the ions in the surface layer of substrate 12 adjacent first major surface 18 and the larger ions are Li. + (if present in glass), Na + , K. + , Rb + , and Cs + Alternatively, the monovalent cations in the surface layer of the substrate 12 are monovalent alkali metal ions such as Ag + It may be substituted with monovalent cations other than alkali metal ions, such as:

[0113] In such embodiments, the replacement of smaller metal ions with larger metal ions in the ion exchange process creates a region of compressive stress in substrate 12 that extends from first major surface 18 to a depth under compressive stress (referred to as the "depth of layer"). This compressive stress in substrate 12 is balanced by a tensile stress (also referred to as the "central tension") within substrate 12. In some embodiments, first major surface 18 of substrate 12 described herein, when strengthened by ion exchange, has a compressive stress of at least 350 MPa, and the region under compressive stress extends from below first major surface 18 to a depth of at least 15 μm into thickness 21, i.e., the depth of layer.

[0114] The ion exchange process is typically carried out by immersing the substrate 12 in a molten salt bath containing larger ions to be exchanged for smaller ions in the glass. Those skilled in the art will recognize that the parameters of the ion exchange process, including but not limited to the bath composition and temperature, immersion time, number of times the glass is immersed in the salt bath(s), use of multiple salt baths, and additional steps such as annealing and rinsing, are generally determined by the composition of the glass and the desired layer depth and compressive stress of the glass as a result of the tempering operation. As an example, ion exchange of an alkali metal-containing glass can be carried out by immersion in at least one molten bath containing salts of larger alkali metal ions, such as, but not limited to, nitrates, sulfates, and chlorides. The temperature of the molten salt bath typically ranges from about 380°C to about 450°C, while the immersion time ranges from about 15 minutes to about 16 hours. However, temperatures and immersion times different from those described above may also be used. Such an ion exchange process, when applied to a substrate 12 having an alkali aluminosilicate glass composition, results in a compressive stress region having a depth (depth of layer) ranging from about 10 μm to at least 50 μm, with a compressive stress ranging from about 200 MPa to about 800 MPa and a central tension of less than about 100 MPa.

[0115] The etching process available for creating scattering regions 20 in substrate 12 can remove alkali metal ions from substrate 12 that would otherwise be replaced by larger alkali metal ions during the ion exchange process, thus prioritizing the creation of compressive stress regions in article 10 after the formation and development of scattering regions 20. [Example]

[0116] Embodiments of the present disclosure will be further understood in light of the following examples.

[0117] Examples 1 to 5 Examples 1-5 were fabricated by forming multiple structures 26 in a basic etching process by varying the degree of adhesion between the resist and the substrate 12. Specifically, an adhesion promoter (HMDS) was deposited on the substrate 12. However, after deposition of the adhesion promoter to vary the adhesion strength to the photoresist (Megaposit™ SPR220, MicroChemicals AZ1500), the water contact angle of the first major surface 18 was varied. The water contact angle was varied by exposing the HMDS layer to tetramethylammonium hydroxide for various exposure times and varying the silane concentration of the promoter. The water contact angle of the first major surface 18 was varied from 75° (strong adhesion and minimal undercut) to 50° (relatively weak adhesion and significant undercut). After determining the pattern of the multiple structures 26 using the methods described herein, the photoresist was exposed to light based on the pattern to promote the formation of openings in the resist and etching of the substrate 12, forming the ground plane 30. Positive or negative resists can be used to achieve similar results. In Example 1, substrate 12 exhibited a water contact angle of approximately 76° before application of the adhesion promoter. In Example 2, substrate 12 exhibited a water contact angle of approximately 71°. In Example 3, substrate 12 exhibited a water contact angle of approximately 68°. In Example 4, substrate 12 exhibited a water contact angle of approximately 61°. In Example 5, substrate 12 exhibited a water contact angle of approximately 50°. For each of Examples 1-5, the photoresist was cured to the same pattern.

[0118] 6A is a 2D surface height profile measured from scattering region 20 of Example 1. This 2D surface height profile was measured on a 1×1 mm 2 area of ​​scattering region 20 measured with a white light interferometer with a lateral resolution of 360 nm per pixel. 2 FIG. 6B shows a portion of the scattering region 20 in Example 5 (high amount of feature rounding). As shown, histogram 610 includes only a single peak 612 representing the fully etched region (establishing ground plane 30). Due to the high degree of feature rounding in this example, the upper peak associated with the single peak height is eliminated. However, as shown in histogram 610, the occurrence of heights higher than the height associated with the single peak 612 is greater than in the area outside the first and second peaks 604 and 606 associated with Example 1. This indicates the gentle slope of the scattering region 20 and the lack of a vertical transition surface.

[0119] AF curves were used to characterize each of Examples 1-5. The AF curves were created by integrating surface height histograms (illustrated by histograms 602 and 610 shown in FIGS. 6A and 6B, respectively) to generate the percentage of surface area occupied by each height. FIG. 7 is a plot including the AF curves for each of these Examples. As shown, AF curve 614 for Example 1 includes a first portion 616 representing the area of ​​scattering region 20 located closer to ground plane 30 (the area of ​​first major surface 18 from which the most material was removed during the basic etching process), a second portion 618 representing a peak portion (e.g., the unetched or least etched portion of substrate 12 from which the least amount of material was removed during the basic etching process), and an intermediate portion 620 extending between first portion 616 and second portion 618. For Example 1, first and second portions 616 and 618 represent the percentage of first major surface 18 located at heights relative to first and second peaks 604 and 606 shown in Figure 6. First and second portions 616 and 618 are vertical portions of the AF curve for Example 1 that have a relatively high or undefined slope. In the illustrated embodiment, first and second portions 616 and 618 have a slope of greater than 420% / μm.

[0120] As described herein, boundaries of the various "portions" (e.g., first portion, second portion, and intermediate portion) of the AF curves described herein can be identified by locating segments of the AF curve where the slope changes abruptly. The portion boundaries can be characterized as segments of the AF curve where the slope transitions by at least 5% / μm over a segment representing 100 nm of surface height, or as inflection points in the AF curve. The inflection points themselves can represent the intermediate portions described herein.

[0121] As shown in FIG. 7 , the slope of the AF curves changed with the degree of feature rounding imparted by reducing the adhesion of the photoresist during the base etch step in Examples 1-5. For Examples 1-5, the second portion of the AF curve (representing the peak portion 42 of the plurality of structures 26) became shorter in length, indicating that a smaller proportion of the first major surface 18 was positioned at a height corresponding to the etch depth in the base etch step relative to the ground plane 30. Furthermore, the intermediate portion of the AF curve (representing the sloped portion 40 of the plurality of structures 26) became more sloped as the degree of feature rounding increased. Illustratively, in AF curve 614 associated with Example 1, the slope of intermediate portion 620 was approximately 0.6% / μm. AF curve 622 associated with Example 4, in contrast, included an intermediate portion 624 having a slope of approximately 238.9% / μm. A greater slope of the intermediate portion generally results in the sloping portions 40 of the plurality of structures 26 occupying a greater area percentage of the first major surface 18 in the scattering region 20 (projected onto the ground plane 30). The AF curve 622 representing Example 4 has an intermediate portion 624 that represents approximately 35% of the scattering region 20. This can be determined based on a projection of the intermediate portion onto the vertical axis of the AF curve. Applicant has found that when the sloping portions 40 of the plurality of structures 26 occupy more than 5% of the total surface area of ​​the scattering region 20 and the intermediate portion of the AF curve has a slope of 5% / μm or more and less than 420% / μm (e.g., 10% / μm or more and 200% / μm or less, 20% / μm or more and 150% / μm or less), the degree of feature rounding is sufficient to provide the excellent washout performance described herein.

[0122] As shown in FIG. 7 , the AF curve 626 associated with Example 5 includes a first portion 628, which is a substantially vertical portion representing the maximally etched portion of the first major surface 18; a second portion 632, which represents the peak portion 42 of the plurality of structures 26; and an intermediate portion 634. The second portion 632 differs in shape from those of Examples 1-4 due to a high degree of feature rounding. Because there is no plateau in the peak height and the features are fully rounded, the second portion 632 is a relatively small segment at the highest height where the AF curve 626 transitions from zero to a finite slope. The intermediate portion 634 has a relatively high slope (approximately 375% / μm) as a result of the high degree of feature rounding.

[0123] "Washout" metrics have been developed to quantify the impact of glare events (e.g., exposure to sunlight) on the contrast and resolution of the incorporated display. Such metrics are useful for testing cover material performance for applications that may involve exposure to light from external sources (e.g., in-car displays, outdoor displays). To quantify "washout," the modulation transfer function (MTF) of the anti-glare surface is measured under various lighting conditions, and the average value of the MTF over a number of spatial frequencies is used to assess the impact of the lighting conditions on the display performance. The MTF at a particular spatial frequency f is

[0124]

number

[0125] where:

[0126]

number

[0127] and I(f) max and I(f) min are the maximum and minimum intensities of the input or output modulation image at spatial frequency f. In this equation, MF in represents the MF value associated with the input pattern emitted through the sample cover material. out The values ​​represent the MTF value when the cover material is placed over an input pattern (e.g., from a display) under the lighting conditions being tested. A higher MTF value generally means that the lighting conditions have less of an effect on display performance (and therefore the scattering region of the cover material performs better). In embodiments, an MTF value of 0.60 or greater (e.g., 0.65 or greater, 0.70 or greater, 0.75 or greater, 0.76 or greater, 0.77 or greater, 0.78 or greater, 0.79 or greater, 0.80 or greater, 0.81 or greater, 0.82 or greater, 0.83 or greater, 0.84 or greater, 0.85 or greater, 0.86 or greater, 0.87 or greater, 0.88 or greater, 0.89 or greater, 0.90 or greater, 0.91 or greater, 0.92 or greater, 0.93 or greater, 0.94 or greater, and 0.95 or greater) is preferred for a given lighting condition and indicates minimal degradation of display performance caused by exposure to external light.

[0128] 8 shows a schematic diagram of an apparatus 800 for measuring the washout effect. As shown, a sample 802 (e.g., corresponding to substrate 12 described herein) is placed on top of a display 804. The sample 802 is positioned so that the scattering region faces outward (rather than towards the display 804). As shown in box 805 (showing a front view of the sample 802 and display 804), the display 804 measures the intensity of the light emitted by the display 804 at a particular spatial frequency f i The target pattern 806 is generated by varying the incident angle θ. A plurality of first light sources 808 are distributed around the sample 802. The plurality of first light sources 808 (e.g., room lamps) are configured to emit light at a relatively low intensity to simulate the sample 802 encountering normal ambient conditions (e.g., room lamps). As reported herein, the plurality of first light sources 808 are configured to emit white light having 130 lux and a color temperature of 2100 K. The projection light source 810 is configured to emit light at a relatively high intensity to simulate sunlight illumination. The projection light source 810 is configured such that the light emitted thereby is incident at an incident angle θ i In an embodiment, the projection light source 810 is positioned to be incident on the sample at an angle of incidence θ i In an embodiment, the projection light source 810 emits light over an emission area, and thus the light emitted by the projection light source 810 is incident over a range of angles of incidence θ i The beam is incident on the sample 802 at .

[0129] A camera 812 is positioned to receive light scattered from the sample 802. The camera receives light scattered from the sample 802 at a viewing angle θ v (or a range of viewing angles) into the camera 812. In an embodiment, the camera 812 has a viewing angle θ v The camera 812 may be movable or otherwise adjustable to vary the MTF value. A calculation system 814 receives the image generated by the camera 812 and analyzes the image to calculate multiple MTF values ​​for each of the multiple target patterns 806 emitted by the display 804. For each target pattern 806, the calculation system 814 calculates an MTF value using Equations 8 and 9 and generates an output measuring the dependence of the MTF value on spatial frequency. With multiple first light sources 808 and projected light sources 810, the MTF values ​​can be measured under multiple different lighting conditions to determine the effectiveness of the pattern on the sample 802 without reducing washout. If only the first light source 808 is emitting light, a "room lamp washout" effect can be measured. If both the first light source 808 and the projected light source 810 are emitting light, a "sunlight washout" effect can be measured.

[0130] Such washout measurements may be particularly useful in evaluating the performance of cover materials for vehicle interior displays. FIG. 9 illustrates a vehicle interior 1000 with three different vehicle interior systems 100, 200, and 300, according to an exemplary embodiment. Vehicle interior system 100 includes a center console base 110 having a surface 120 with a display 130. Vehicle interior system 200 includes a dashboard base 210 having a surface 220 with a display 230. Dashboard base 210 typically includes an instrument panel 215, which may also include a display 216. Vehicle interior system 300 includes a dashboard steering wheel base 310 having a surface 320 and a display 330. In one or more embodiments, the vehicle interior system may include a base that is any part of the vehicle interior, including an armrest, pillar, seatback, floorboard, headrest, door panel, or surface. In an embodiment, display 130, 230, or 330 is flat and includes a cover glass with a planar major surface. In embodiments, one or more of the displays 130, 230, 330 are curved, and the curved display may include a curved cover glass that may be hot-formed or cold-formed to have such a curvature. For example, such an embodiment may incorporate an opaque layer formed from a photocurable ink described herein disposed on a cold-formed glass substrate.Such cold forming may include any of the techniques described in U.S. Patent Application Publication No. 2019 / 0329531 A1, entitled "Laminating thin strengthened glass to curved molded plastic surface for decorative and display cover applications," U.S. Patent Application Publication No. 2019 / 0315648 A1, entitled "Cold-formed glass article and assembly process thereof," U.S. Patent Application Publication No. 2019 / 0012033 A1, entitled "Vehicle interior systems having a curved cover glass and a display or touch panel and methods for forming the same," and U.S. Patent Application No. 17 / 214124, entitled "Curved glass constructions and methods for forming the same," all of which are hereby incorporated by reference in their entireties.

[0131] Various components of the vehicle interior 1000 may be exposed to illumination from various light sources. For example, as shown in FIG. 9, a first ambient light source 900 is transmitted through a first side window of the vehicle at an angle of incidence θ i1 The display 216 can emit light incident on the display 216 at a particular scattering angle θ v1 The light scattered by the second ambient light source 902 is transmitted through a second side window of the vehicle at an incident angle θ i2 The display 130 can emit light incident on the display 130 at a particular scattering angle θ v2 The first and second ambient light sources 900 and 902 may represent sunlight at various times. Indeed, the ISO 15002 / SA 1757 standard defines a first condition (i.e., θ 2 , associated with the "Washout 1" index herein) in which 45k lux light (direct sunlight) is incident on the display 216 at an angle of 20° and scattered towards the driver at a scattering angle of 0°. i1 = 20° and θ v1 =0°), and a second condition where 45k lux light (direct sunlight) is incident on the display 130 at an angle of 45° and scattered towards the driver at a scattering angle of 20° (i.e., θ =0°, associated with the “Washout 2” metric herein). i2 = 45° and θ v2 = 20°). The apparatus 800 shown in Figure 8 can test such conditions for washout by changing the orientation of the sample 802 and adjusting the projection light source 810.

[0132] Using the apparatus 800 shown in FIG. 8, Examples 1-5 were tested using the two standards of ISO 15002 / SA 1757 described herein. An Apple® mini-iPad® 4 was used as the display 804. A Pixelink 3.1 MP PL-B776 was used as the camera 812. A collimated LED light source (emitting 45,000 lux of white light) was used as the projection light source 810 (manufactured by Mightex Systems, model LCS-6500-65-22). Multiple projection light sources were used and positioned to emit light incident on the sample 802 at angles of incidence of 20° and 45°. The sample 802 and camera 812 were also positioned at a viewing angle θ v and the angle of incidence θ i The lamp was mounted on a rotation stage to allow adjustment between two conditions: A laboratory room lamp was used as the first light source 808 and was measured to have a luminance of 132 lux.

[0133] To quantitatively assess the effect of Sample 802, MTF values ​​at spatial frequencies of 1.67 cycles / mm, 4.11 cycles / mm, 7.33 cycles / mm, 10.38 cycles / mm, and 13.08 cycles / mm were averaged for each series. The "washout" index described herein was the average of the MTF values ​​across these spatial frequencies for each condition.

[0134] Figure 10 is a plot of the Washout 2 Index described herein with respect to Figures 8 and 9 as a function of the water contact angle of the substrate after deposition (and modification) of an adhesion promoter. As shown, the Washout 2 Index is generally less than 0.5 for water contact angles greater than 65°. However, when the photoresist exhibits water contact angles less than 65°, the Washout 2 Index exceeds 0.6, indicating more favorable washout performance. These results indicate that surfaces characterized by AF curves with a higher degree of feature rounding, and therefore the characteristics described herein, are associated with better washout performance.

[0135] Examples 6 to 11 In Examples 6-11, Corning Gorilla® Glass 5 was used as the substrate. To perform the basic etching, an adhesive layer (HMDS) was applied to the first major surface. Next, a photoresist ("Megaposit" SPR220, MicroChemicals AZ1500) was applied to this adhesive layer to a thickness of less than 2 μm. A positive tone was used, so that the areas exposed to UV light were removed with an alkaline developer (<1% TMAH tetramethylammonium hydroxide or 0.24% by weight potassium hydroxide or 1% by weight sodium carbonate Na2CO3), while the unexposed areas were unaffected by the developer. Finally, wet etching (dipping / spraying) was used to transfer the patterned features into the glass. The basic etchant was room-temperature hydrofluoric acid (e.g., HF / HNO3 or HF / HCl). Typically, an acid-etch-resistant film was laminated to the unmasked side to prevent etching. The same pattern was formed in each of Examples 6-11 using a basic etching process.

[0136] A secondary etching step was performed by spraying the secondary etchant onto the top surface of the glass, which was then positioned vertically, allowing the etchant to flow across the surface under the influence of gravity from the top to the bottom of the sample. The concentration of the secondary etchant was varied from 16 mM HF / 20 mM HCl to 160 mM HF / 200 mM HCl to achieve an etching rate of 0.1 to 1 μm / min. The etching time was varied from 5 to 20 minutes. Examples 6 and 7 utilized an etching rate of 1 μm / min. Examples 8 and 9 utilized an etching rate of 0.02 μm / min. Examples 10 and 11 utilized an etching rate of 0.1 μm / min. The optical properties of the samples were measured both before and after the secondary etching. The results are shown in Table 1 below. Three samples were measured for each etching regime.

[0137] [Table 1]

[0138] As shown, a systematic difference between the samples before and after the secondary spray etching process is that the samples exhibited lower transmission haze after the secondary etching process. Therefore, transmission haze can be used to monitor the secondary etching process described herein. Furthermore, the samples that underwent secondary etching exhibited specular reflectance, DOI, and gloss values ​​comparable to the unpolished samples. These results demonstrate that the feature rounding imparted by the methods described herein can help improve washout performance without degrading other important AR performance attributes.

[0139] 11A, 11B, and 11C are AF curves representing the surfaces of Examples 6-11. These curves generally illustrate how the secondary etching process alters the profile of the first major surface 18. Each of FIGS. 11A, 11B, and 11C includes a control AF curve representing the sample before the secondary etching. FIG. 11A represents Examples 6 and 7, which were formed using an etching rate of 1 μm / min in the secondary etching process. As shown in the AF curve associated with Example 6, a 5-minute etching period reduced the fill fraction of the scattering region 20 occupied by the portion of the first major surface 18 located at the etch depth of the basic etching process relative to the ground plane by approximately 8%. The slope of the intermediate portion 1100 (between the vertical portions associated with the plateau height) also increases relative to the control. As shown in the AF curve associated with Example 7, increasing the etching time of the secondary etching process to 20 minutes reduced the fill fraction associated with the portion of the first major surface 18 located at the etch depth of the basic etching process relative to the ground plane by 20%. Additionally, the slope of intermediate portion 1102 is further increased relative to intermediate portion 1100 associated with Example 6. Figures 11B and 11C show that slower etch rates of 0.1 μm / min and 0.2 μm / min can be used to effectively provide feature rounding, with the same etch duration resulting in a smaller decrease in fill fraction of features located at the etch depth of the base etch step relative to the ground plane.

[0140] 12A-12C are SEM images of cross sections of the samples used to measure the AF curves shown in FIGS. 11A, 11B, and 11C. FIG. 12A is an SEM image of one of the samples from Example 9. FIG. 12B is an SEM image of one of the samples from Example 10. FIG. 12C is an SEM image of one of the samples from Example 11. A trend evident in these images is that the total amount of substrate etched during the secondary etching step is proportional to the degree of feature rounding. While no discernible sharp corners are observed in FIG. 12C, associated with a total etching of 20 μm in the secondary etching step, FIG. 12A, associated with a total etching of 4 μm in the secondary etching step, still shows a relatively sharp top corner. Based on these results, it appears that the degree of rounding is not affected by the selected etch rate, but rather by the total amount of etching that occurs during the secondary etching step. A slower etch rate (e.g., 0.1 μm / min) can be used for a longer period (e.g., 200 minutes) to provide the same degree of feature rounding as a faster etch rate (e.g., 1.0 μm / min) for a shorter period (e.g., 20 minutes). However, for manufacturing efficiency, a faster etch rate may be preferred.

[0141] Examples 12 to 14 Examples 12-14 were formed by patterning the first major surface 18 of substrate 12 (fabricated from the same material as Examples 6-11) using the methods described herein. Slightly different etch depths were used in the base etch process to form each of these examples. Figure 13A shows a surface height profile 1300 of a control sample without a secondary etch. As shown, the corresponding histogram 1302 includes a first peak 1304 representing the ground plane 30 and a second peak 1306 representing the peak portion 42 of the plurality of structures 26. The first and second peaks 1304 and 1306 are separated by an etch depth 1308 of approximately 132 nm. To fabricate Examples 12-14, the samples were subjected to an immersion etch process in a 1 M HF / 1 M HCl solution to round the features (the etch depth was slightly different for each of the samples). Figure 13B shows a surface height profile 1310 of Example 12, which was subjected to a 2 minute secondary etch. Figure 13C is a surface height profile 1320 for Example 13, which was subjected to a 3-minute secondary etch. Figure 13D is a surface height profile 1330 for Example 14, which was subjected to an 8-minute secondary etch. As shown in histograms 1312, 1322, and 1332, longer secondary etching periods generally broaden the histogram peaks. For example, histogram 1332 associated with Example 14 includes first and second peaks 1334 and 1336 that are broader than first and second peaks 1304 and 1306 associated with the control sample, which was not subjected to a secondary etch.

[0142] Examples 12-14 were further characterized by AF curves shown in FIG. 14. A first AF curve 1400 relates to the control sample represented by the surface height profile of FIG. 13A. As shown, the first AF curve 1400 includes a first portion 1402 representing the region of the first major surface etched in the basic etching step, and a second portion 1404 representing the portion of the first major surface not etched during the basic etching step. The first AF curve 1400 further includes an intermediate portion 1406 extending between the first portion 1402 and the second portion 1404. As a result of the lack of feature rounding, the intermediate portion 1406 has a relatively small slope of approximately 25% / μm when the etch depth is approximately 0.18 μm. A second AF curve 1408 represents Example 12. The second AF curve 1408 includes a first portion 1410, a second portion 1412, and an intermediate portion 1414. As shown, the middle portion 1414 has an average slope of about 83% / μm, which is greater than that of the control sample as a result of the feature rounding imparted by the small amount of secondary etching. The third AF curve 1416 associated with Example 13 includes a middle portion 1418 having an average slope of about 100% / μm, which is even greater than that of Example 12 as a result of the longer secondary etching step. The fourth AF curve 1420 associated with Example 14 includes a middle portion 1422 having an average slope of about 154% / μm, which is even greater than that of Example 13 as a result of the longer secondary etching step. These examples demonstrate that the slope of the middle portion of the AF curve is generally proportional to the amount of material removed during the secondary etching step described herein and can be controlled by selecting an appropriate etch rate and duration.

[0143] Bidirectional reflectance distribution function (BRDF) measurements were performed on Examples 12-14, as well as a comparative example fabricated using a conventional maskless HF etching process (which generates a random pattern). Measurements were performed in reflectance mode using a REFLET 180S system from Synopsys, Inc. The measurement wavelength range (i.e., the spectral range of the source of scattered light) was from 400 nm to 1700 nm at an angle of incidence of 10°. Figure 15 shows the scattering amplitude (sr -1 ) plot. As shown, the feature-rounded samples exhibited lower scattering intensities at scattering angles greater than 30° relative to the specular direction. Indeed, at a scattering angle of 30°, in terms of actual (unnormalized) BRDF amplitude, Example 14 exhibited a BRDF amplitude of 1.2×10 at a scattering angle of 30°. -4 sr -1 The control exhibited a BRDF amplitude of less than 4 × 10 -4 sr -1 These differences are even greater at higher scattering angles. At a scattering angle of 40°, Example 14 exhibited a BRDF amplitude of 5×10 -5 sr -1 The control showed a BRDF amplitude of 1.7 × 10 -4 sr -1 Such low BRDF amplitudes at high scattering angles achieved by the feature-rounded samples demonstrate the excellent washout performance of such samples.

[0144] Examples 15 to 17 Examples 15-17 differed from the previous examples in that the base etching step included multiple sub-etching steps to produce a surface height profile with three or more modes. FIG. 16A shows a surface height profile 1600 of a control sample without any secondary etching. As shown in histogram 1602, the surface height profile includes a first peak 1604 associated with regions of the first major surface 18 that were not etched during the base etching step, and a second peak 1606 associated with regions of the first major surface 18 that were etched during both sub-etching steps of the base etching step. Intermediate peaks 1607 and 1608 associated with regions of the first major surface 18 that were etched during only one of the sub-etching steps of the base etching step. To produce Examples 15-17, samples having the surface height profile shown in FIG. 16A were subjected to a dip etching step in a 1M HF / 1M HCl solution to round the features. FIG. 16B shows a surface height profile 1610 for Example 15, which underwent a 0.5-minute secondary etch. FIG. 16C shows a surface height profile 1620 for Example 16, which underwent a 3-minute secondary etch. FIG. 16D shows a surface height profile 1630 for Example 17, which underwent a 5-minute secondary etch. As shown in histograms 1612, 1622, and 1632, increasing the duration of the secondary etch generally broadens the histogram peaks. In fact, histograms 1622 and 1632 associated with Examples 16 and 17 only show three distinct peaks because the intermediate peaks merged due to feature rounding. For example, as shown in FIG. 16D, histogram 1632 includes a first peak 1634 associated with a region of first major surface 18 that was not etched during the base etch step and a second peak 1636 associated with a region of first major surface 18 that was etched during both of the sub-etch steps of the base etch step. However, histogram 1632, in contrast to histogram 1612 associated with Example 15, contains only one clear intermediate peak 1638.

[0145] AF curves were used to further characterize Examples 15-17, and the curves are shown in FIG. 17. As shown, a longer secondary etch step generally results in vertical portions of the AF curves with smaller slopes due to feature rounding. Vertical portions with slopes less than 400% / μm generally indicate a relatively high degree of feature rounding and minimal planar area of ​​the scattering region 20. Each of the AF curves associated with Examples 15-17 can be characterized as having four distinct vertical portions, each with an average slope greater than 350% / μm. The vertical portions represent peak portions 42 of multiple structures 26 at different peak heights in their respective histograms. The vertical portions are separated from one another by intermediate portions that are either (a) segments of the AF curve at least 50 nm in height that have an average slope at least 50% / μm less than adjacent vertical portions, or (b) inflection points of the AF curve. To illustrate, FIG. 17 includes an AF curve 1700 associated with Example 17. In this example, the features are significantly rounded. AF curve 1700 includes a first portion 1702 representing the location on first major surface 18 where the most material was removed during the base and secondary etching steps, a second peak portion 1704 representing the location where the least material was removed during the base and secondary etching steps, a third portion 1706, and a fourth portion 1708. Third and fourth portions 1706 and 1708 are related to intermediate peak 1638 described herein with respect to FIG. 16D . First, second, third, and fourth portions 1702, 1704, 1706, and 1708 are vertical portions of AF curve 1700, each having an average slope of greater than 350% / μm.

[0146] The AF curve 1700 further includes a first intermediate portion 1710, a second intermediate portion 1712, and a third intermediate portion 1714. The first intermediate portion 1710 separates the second portion 1704 from the third portion 1706 and includes a segment of the AF curve 1700 representing a surface height of approximately 0.1 μm. The first intermediate portion 1710 has an average slope of approximately 150% / μm. The second intermediate portion 1712 is an inflection point of the AF curve 1700 separating the third portion 1706 from the fourth portion 1708. The third intermediate portion 1714 extends between the fourth portion 1708 and the first portion 1702 and includes a segment of the AF curve 1700 representing a surface height of approximately 0.06 μm. The third intermediate portion 1714 has an average slope of approximately 133% / μm. Thus, the AF curve includes four vertical portions having an average slope of 350% / μm or greater, with adjacent vertical portions separated by an intermediate portion that is either (a) a segment of the AF curve at least 50 nm in height that has an average slope at least 50% / μm less than the adjacent vertical portion, or (b) an inflection point of the AF curve. The AF curves associated with Examples 15 and 16 exhibit similar characteristics, with the vertical portions becoming more sloped and the intermediate portions becoming less sloped due to the reduced amount of secondary etching.

[0147] Bidirectional reflectance distribution function (BRDF) measurements were performed on Examples 15-17. Measurements were performed in reflectance mode using a REFLET 180S system from Synopsys, Inc. The measured wavelength range was 400 nm to 1700 nm at an incident angle of 10°. Figure 18 shows the scattering amplitude (sr -1 ) plot. As shown, the feature-rounded samples exhibited lower scattering intensities at scattering angles greater than 30° relative to the specular direction. In terms of actual (unnormalized) BRDF amplitudes, Examples 16 and 17 exhibited 3×10 at a scattering angle of 30°. -5 sr -1 Example 15 shows a BRDF amplitude of less than 9 × 10 -4 sr -1 The BRDF amplitude of the control is 1.5 x 10 -3 sr -1 The BRDF amplitude is shown.

[0148] In general, samples produced using multiple sub-etch steps in a basic etch process tend to have increased sparkle and haze compared to those produced using a single sub-etch step. However, multiple sub-etch step designs can significantly reduce specular reflection and combined image clarity. The presence of multiple heights can provide interference suppression of specular reflection over a wide optical bandwidth. In general, the design used will be determined by the performance attributes designed for a particular application. A single sub-etch design may be desirable for applications where low haze, sparkle, and excellent washout performance (such as in automotive interior displays) are desired, while a multiple sub-etch design may be suitable for applications requiring excellent specular reflectance reduction and / or DOI.

[0149] Examples 18 to 22 Examples 18-22 were fabricated in a manner similar to Examples 6-11 herein (using a single sub-etching step, a base etching step, followed by a secondary etching step of varying duration). The base etching step for Examples 18-22 was designed so that the portion of the first major surface 18 not etched during the base etching step accounted for approximately 75% of the total surface area of ​​the scattering region 20. This was done so that the fill fraction with this elevation difference was approximately 50% after the secondary etching step. Such a 50% fill fraction is believed to be associated with excellent specular reflectance performance. The secondary etching step duration varied from 9 to 13 minutes. The amount of scattering region 20 located at the etch depth of the base etching step relative to the ground plane 30 after the secondary etching step decreased in proportion to the length of the secondary etching step. The longer the secondary etching step, the greater the percentage decrease in fill fraction associated with the portion of the scattering region located at the etch depth of the base etching step relative to the ground plane 30 after the secondary etching step. The optical properties of the examples, as well as the comparative examples fabricated using a random HF etching step without a mask, were measured. The results are shown in Table 2 below.

[0150] [Table 2]

[0151] As shown, relative to the Comparative Example, each of Examples 18-22 exhibits significantly lower specular reflectance (each exhibiting an Rs value of less than 6.2), DOI (each exhibiting a combined DOI of less than 70%), and transmission haze (each exhibiting a transmission haze of less than 3%) than the Comparative Example. Additionally, each exhibits a Washout 1 Index value (for light incident on the scattering region at a 20° angle of incidence and a 0° viewing angle) described herein of greater than 0.7, a significant improvement over the Comparative Example. These results demonstrate the ability of the scattering region described herein to achieve superior washout performance with minimal to no adverse impact on other optical properties, including haze, DOI, R-spec, PPD, and color breakup.

[0152] Example 23 Two samples were subjected to CS8 wear testing to determine whether the feature rounding imparted by the method described herein provided any performance benefits in terms of wear resistance. FIG. 10 shows a surface height profile 1900 and histogram 1902 associated with a baseline surface design in which no secondary etching was performed. As shown, the etch depth associated with the base etch step was approximately 172 nm, and the surface was designed to have a 50% fill fraction associated with the unetched portion of first major surface 18. FIG. 20 shows a surface height profile 2000 and histogram 2002 associated with Example 23, which is an improved design based on the design shown in FIG. 19 after undergoing a secondary etch (1 M HF / 1 M HCl (immersion etch) for 2400 seconds). As shown in histogram 2002, the secondary etch resulted in feature rounding, indicated by broadening of the peaks and an increase in the peak-to-peak height count. This feature rounding is also associated with the sloped portions 40 of the structures 26 having a greater slope, and therefore a greater transition width, than in the control shown in FIG.

[0153] The samples shown in Figures 19-20 were subjected to the CS8 abrasion test. In this test, a 270 g normal load was applied to the commercially available CS8 material (made from a rubber matrix with embedded particles). The CS8 material was moved with a stroke length of 25 mm at a rate of 60 cycles per minute. The scattering area underwent 100 cycles of pad movement. The results are shown in Figures 21A and 21B. Figure 21A shows the results for the control sample, which did not undergo secondary etching. Figure 21B shows the results for Example 23. As can be seen, the feature rounding provided by the secondary etching significantly reduced the visibility of the wear scar caused by the particles. This visibility was quantified using a dark-field light scattering imaging system. The system was equipped with an annular light source (24 cm diameter) that emitted white light with an intensity of approximately 10,000 lux onto the scattering area. A digital camera (positioned 25 cm linear distance from the sample) captured images of the sample illuminated by the annular light source. The abrasion-damaged areas had different light reflection properties compared to the unabraded sections. Trace visibility was defined by quantifying the contrast between the abraded and unabraded areas. To do so, the images were digitized and the intensity of each pixel was represented using a grayscale where black was 0 and white was 255. A threshold was established for the unabraded sections, and each pixel with a grayscale value greater than the threshold was characterized as being associated with a worn section. For each pixel characterized as being associated with a worn section, a trace visibility value was calculated as follows:

[0154]

number

[0155] In the formula, I 摩耗 is the measured pixel intensity associated with the pixel characterized as being associated with the wear section, and I 非摩耗 is the measured pixel intensity associated with the nearest pixel characterized as non-wear. FIG. 22 shows a histogram of trace visibility values ​​for pixels characterized as associated with wear areas for the samples shown in FIGS. 21A and 21B. As shown, Example 23 exhibited an average trace visibility of less than 20%, which was less than 40% of the maximum trace visibility value. The control sample, which did not undergo a secondary etch, exhibited an average trace visibility of more than 40%, with a maximum value exceeding 85%. These results confirm the visual observations in FIGS. 21A and 21B. The feature rounding provided by the secondary etch described herein reduces the visibility of damage from abrasive particles, which is beneficial for touch applications where particulate debris is likely to be encountered.

[0156] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a particular order. Thus, unless a method claim actually recites the order in which its steps should be followed, or unless the claim or description specifically states that the steps are to be limited to a particular order, no particular order is intended to be implied. Additionally, as used herein, nouns are intended to refer to one or more components or ingredients, and are not intended to be construed as referring to just one.

[0157] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the disclosed embodiments. Since modifications, combinations, sub-combinations, and variations of the disclosed embodiments, including the spirit and substance of the embodiments, will occur to those skilled in the art, the disclosed embodiments should be construed as including all within the scope of the appended claims and equivalents thereof.

[0158] Preferred embodiments of the present invention will be described below in detail.

[0159] Embodiment 1 A substrate, a first major surface; a second major surface opposite the first major surface; and a scattering region formed in the first major surface; and Within the scattering region, the first major surface has a plurality of structures extending outwardly from a ground plane of the first major surface, each structure extending from the ground plane to a peak height; and each of the plurality of structures includes a sloped portion extending from the ground plane and a peak portion disposed at a peak height of the structure; the sloped portions of the plurality of structures occupy more than 5% of the total surface area of ​​the scattering region; 1×1 mm of the scattering area 2 The Abbott-Firestone curve characterizes the part, a first portion representing an area of ​​the scattering region located closest to the ground plane; a second portion representing a peak portion of the plurality of structures; and an intermediate portion extending between the first portion and the second portion; Including, a substrate, wherein the intermediate portion has an average gradient of less than 420% / μm and greater than 5% / μm; An item equipped with:

[0160] Embodiment 2 2. The article of embodiment 1, wherein the angled portion accounts for more than 50% of the total surface area of ​​the scattering region.

[0161] Embodiment 3 At least some of the plurality of peak portions are etched depth portions located within 20 nm of a maximum peak height relative to the ground plane; the etched depth portion occupies less than 60% of the total surface area of ​​the scattering region; 2. The article of embodiment 1.

[0162] Embodiment 4 4. The article of claim 3, wherein the etched depth portion occupies less than 40% of the total surface area of ​​the scattering region.

[0163] Embodiment 5 5. The article of any one of claims 1 to 4, wherein the plurality of structures have a maximum feature size of 1 μm or more and less than 200 μm.

[0164] Embodiment 6 6. The article of any one of claims 1 to 5, wherein at least some of the sloping portions extend a lateral distance between the ground plane and the peak portion of 1.0 μm or more and 10 μm or less, the lateral distance over which the sloping portions extend being measured in a direction parallel to a surface normal of the sloping portion and parallel to the ground plane.

[0165] Embodiment 7 7. The article of claim 6, wherein the lateral distance is 3.0 μm or greater.

[0166] Embodiment 8 each of the sloping portions includes a first edge disposed proximate the ground plane and a second edge disposed proximate the peak portion; the slope of the first major surface varies along a direction over a lateral distance of 1 μm at both the first edge and the second edge; 8. The article of embodiment 6 or 7.

[0167] Embodiment 9 9. The article of any one of claims 1 to 8, wherein the first and second portions of the Abbott-Firestone curve are vertical portions having a gradient of greater than 350% / μm.

[0168] Embodiment 10 some of the peaks are located within 20 nm of a maximum peak height relative to the ground plane, and those peaks are represented in the second portion of the Abbott-Firestone curve; the Abbott-Firestone curve includes a third vertical portion representing a peak portion disposed at a peak height between the ground plane and the maximum peak height; 10. The article of embodiment 9.

[0169] Embodiment 11 5. The Abbott-Firestone curve, a fourth vertical portion representing an additional peak portion located at a peak height between the ground plane and the maximum peak height other than a height associated with the third vertical portion; further comprising The intermediate portion is a first intermediate portion disposed between the first portion and the third vertical portion; a second intermediate portion disposed between the third vertical portion and the fourth vertical portion; and a third intermediate portion disposed between the fourth vertical portion and the second portion; Including, 11. The article of embodiment 10.

[0170] Embodiment 12 12. The article of claim 11, wherein each of the first intermediate portion, the second intermediate portion, and the third intermediate portion is either (a) a segment of the Abbott-Firestone curve at least 50 nm in height having an average slope at least 50% / μm less than an adjacent vertical portion, or (b) an inflection point of the Abbott-Firestone curve.

[0171] Embodiment 13 The article is Transmission haze of 3.5% or less, and Less than 2.5% sparkle measured at 140ppi 13. The article of any one of embodiments 1 to 12, wherein:

[0172] Embodiment 14 The bidirectional reflectance distribution function ("BRDF") of the article, measured from white light incident on the first major surface at an angle of incidence of 10°, is 1.2 x 10 at a scattering angle of 30° relative to the specular direction. -4 sr -1 14. The article of any one of claims 1 to 13, exhibiting a strength of less than

[0173] Embodiment 15 15. The article of any one of claims 1 to 14, wherein the first average modulation transfer function of the article averaged over spatial frequencies of 1.67 cycles / mm, 4.11 cycles / mm, 7.33 cycles / mm, 10.38 cycles / mm, and 13.08 cycles / mm is at least 0.7 when the article is viewed at a viewing angle of 0° and light having a luminance of 45,000 lux is incident on the first major surface at an angle of incidence of 20°.

[0174] Embodiment 16 16. The article of any one of the preceding claims, wherein the scattering region exhibits a mark visibility of 40% or less after 100 cycles of a pad applying a 270g force to the CS8 material along a mark against the scattering region.

[0175] Embodiment 17 A substrate, a first major surface; a second major surface opposite the first major surface; and a scattering region formed in the first major surface; and Within the scattering region, the first major surface has a plurality of structures extending outwardly from a ground plane of the first major surface, each structure extending from the ground plane to a peak height; and each of the plurality of structures includes a sloped portion extending from the ground plane and a peak portion located at a peak height of the structure, such that the scattering region includes a plurality of sloped portions and a plurality of peak portions; at least some of the sloping portions extend a lateral distance between the ground plane and the peak portion that is greater than or equal to 1.0 μm and less than or equal to 10 μm; the lateral distance that the sloped portion extends is measured in a direction parallel to a surface normal of the sloped portion and parallel to the ground plane; the sloped portions of the plurality of structures occupy more than 5% of the total surface area of ​​the scattering region; 1×1 mm of the scattering area 2 a substrate, wherein an Abbott-Firestone curve characterizing the portion does not include any horizontal portion of a height of at least 0.05 μm having a gradient of less than 40% / μm between a height representing the ground plane and a peak height of the scattering region; An item equipped with:

[0176] Embodiment 18 18. The article of claim 17, wherein the angled portion accounts for more than 5% of the total surface area of ​​the scattering region.

[0177] Embodiment 19 At least some of the plurality of peak portions are etched depth portions located within 20 nm of a maximum peak height relative to the ground plane; the etched depth portion occupies less than 60% of the total surface area of ​​the scattering region; 19. The article of embodiment 17 or 18.

[0178] Embodiment 20 20. The article of claim 19, wherein the etched depth portion occupies less than 40% of the total surface area of ​​the scattering region.

[0179] Embodiment 21 21. The article of any one of claims 17 to 20, wherein the plurality of structures have a maximum feature size of 1 μm or more and less than 200 μm.

[0180] Embodiment 22 the sloped portion of each structure includes a first edge disposed proximate the ground plane and a second edge disposed proximate a peak portion of the structure; the slope of the first major surface varies along a direction over a lateral distance of 1 μm at both the first edge and the second edge; 22. The article of any one of embodiments 17 to 21.

[0181] Embodiment 23 5. The Abbott-Firestone curve, a first portion representing an area of ​​the scattering region located closest to the ground plane; a second portion representing a peak portion of the plurality of structures; and an intermediate portion extending between the first portion and the second portion; Including, the intermediate portion has an average gradient of less than 420% / μm and greater than 5% / μm; the first and second portions of the Abbott-Firestone curve are vertical portions having a gradient of greater than 350% / µm; some of the peaks are located within 20 nm of a maximum peak height, and those peaks are represented in the second portion of the Abbott-Firestone curve; 23. The article of any one of embodiments 17 to 22.

[0182] Embodiment 24 24. The article of claim 23, wherein the Abbott-Firestone curve includes a third vertical portion representing a peak portion located at an height between the ground plane and the maximum peak height.

[0183] Embodiment 25 5. The Abbott-Firestone curve, a fourth vertical portion representing an additional peak portion located at a peak height between the ground plane and the maximum peak height other than a height associated with the third vertical portion; further comprising The intermediate portion is a first intermediate portion disposed between the first portion and the third vertical portion; a second intermediate portion disposed between the third vertical portion and the fourth vertical portion; and a third intermediate portion disposed between the fourth vertical portion and the second portion; Including, 25. The article of embodiment 24.

[0184] Embodiment 26 26. The article of claim 25, wherein each of the first intermediate portion, the second intermediate portion, and the third intermediate portion is either (a) a segment of the Abbott-Firestone curve at least 50 nm in height having an average slope at least 50% / μm less than an adjacent vertical portion, or (b) an inflection point of the Abbott-Firestone curve.

[0185] Embodiment 27 The article is Transmission haze of 3.5% or less, and Less than 2.5% sparkle measured at 140ppi 27. The article of any one of embodiments 17 to 26, wherein:

[0186] Embodiment 28 The bidirectional reflectance distribution function ("BRDF") of the article, measured from white light incident on the first major surface at an angle of incidence of 10°, is 1.2 x 10 at a scattering angle of 30° relative to the specular direction. -4 sr -1 28. The article of any one of claims 17 to 27, exhibiting a strength of less than

[0187] Embodiment 29 29. The article of any one of claims 17 to 28, wherein the first average modulation transfer function of the article averaged over spatial frequencies of 1.67 cycles / mm, 4.11 cycles / mm, 7.33 cycles / mm, 10.38 cycles / mm, and 13.08 cycles / mm is at least 0.7 when the article is viewed at a viewing angle of 0° and light having a luminance of 45,000 lux is incident on the first major surface at an angle of incidence of 20°.

[0188] Embodiment 30 30. The article of any one of claims 17 to 29, wherein the scattering region exhibits a mark visibility of 40% or less after 100 cycles of a pad applying a 270g force to the CS8 material along a mark against the scattering region.

[0189] Embodiment 31 1. A method of forming a scattering region of a substrate for a display article, comprising: determining a pattern of a plurality of structures on a first major surface of the substrate, each of the plurality of structures having a surface area disposed at a height measured relative to a ground plane spanning the display article; disposing one or more etch masks on the first major surface that permit etching only on selected areas of the first major surface to form at least some of the plurality of structures; and placing each etching mask of the one or more etching masks on the first major surface and then contacting the display article with an etching solution for a period of time to form the plurality of structures in a basic etching process; removing the one or more etch masks from the first major surface; exposing the entire scattering region to a secondary etchant such that the plurality of structures includes sloped portions and corners of the plurality of structures are rounded; A method comprising:

[0190] Embodiment 32 32. The method of claim 31, wherein exposing the entire scattering region to a secondary etchant comprises immersing the article in a secondary etchant having a concentration ratio of HF to HCl ranging from 0.5M HF / 0.5M HCl to 3M HF / 3M HCl, such that the etch rate of the article is greater than 0.5 μm / min.

[0191] Embodiment 33 32. The method of claim 31, wherein exposing the entire scattering region to a secondary etchant comprises spraying the article with a secondary etchant having a concentration ratio of HF to HCl of 16 mM HF / 20 mM HCl to 160 mM HF / 200 mM HCl to achieve an etch rate of 0.1 μm / min to 1 μm / min.

[0192] Embodiment 34 34. The method of any one of claims 31 to 33, wherein exposing the entire scattering region to a secondary etching solution is carried out for a secondary etching period of 20 minutes or less, such that 20 μm or less of material is removed from the scattering region.

[0193] Embodiment 35 35. The method of any one of claims 31 to 34, wherein after the basic etching step, the plurality of structures comprises a plurality of regions of the first major surface that are disposed at different heights relative to the ground plane, the heights differing from one another by 20 nm to 200 nm in a direction perpendicular to the ground plane.

[0194] Embodiment 36 36. The method of any one of claims 31 to 35, wherein exposing the entire scattering region to a secondary etching solution reduces the fill fraction of the scattering region, which is comprised of portions of the article not etched in the basic etching step, by at least 5%. [Explanation of symbols]

[0195] 10 Goods 12 PCB 14. Case 16 Display 18 First principal surface 19 Second main surface 20 scattering area 22 Incident ray 24 External environment 25 Scattered rays 26 Multiple Structures 30 base plane 32 First Part 33, 46 Surface normal 36 First partial structure 38 Second substructure 40 Slope section 42 Peak part 43 First Edge 44 Second Edge 100, 200, 300 cabin systems 110 Center console base 120, 220, 320 surface 130, 230, 330 Display 210 Dashboard Base 215 Instrument Panel 310 Dashboard handle base 802 samples 804 Display 806 Target Pattern 808 First Light Source 810 Projection light source 812 Camera 814 Calculation Systems, Computers 900 First ambient light source 902 Secondary Ambient Light Source 1000 cabin< / psd>

Claims

1. A substrate, a first major surface; a second major surface opposite the first major surface; and a scattering region formed in the first major surface; and Within the scattering region, the first major surface has: a plurality of structures extending outwardly from a ground plane of the first major surface, each structure extending from the ground plane to a peak height; and each of the plurality of structures includes a sloped portion extending from the ground plane and a peak portion disposed at a peak height of the structure; the sloped portions of the plurality of structures occupy more than 5% of the total surface area of ​​the scattering region; 1×1 mm of the scattering region ２ The Abbott-Firestone curve characterizing the part a first portion representing an area of ​​the scattering region located closest to the ground plane; a second portion representing a peak portion of the plurality of structures; and an intermediate portion extending between the first portion and the second portion; Including, a substrate, wherein the intermediate portion has an average gradient of less than 420% / μm and greater than 5% / μm in magnitude; An item equipped with:

2. The article of claim 1 , wherein the angled portion comprises more than 50% of the total surface area of ​​the scattering region.

3. At least some of the plurality of peak portions are etched depth portions located within 20 nm of a maximum peak height relative to the ground plane, the etched depth portion occupies less than 60% of the total surface area of ​​the scattering region; 10. The article of claim 1.

4. 4. The article of claim 1, wherein at least some of the sloping portions extend a lateral distance between the ground plane and the peak portion of at least 1.0 μm and no more than 10 μm, the lateral distance over which the sloping portions extend being measured in a direction parallel to a surface normal of the sloping portions and parallel to the ground plane.

5. each of the sloping portions includes a first edge disposed proximate the ground plane and a second edge disposed proximate the peak portion; the slope of the first major surface varies along a direction over a lateral distance of 1 μm at both the first edge and the second edge; 5. The article of claim 4.

6. 4. The article of claim 1, wherein the first and second portions of the Abbott-Firestone curve are vertical portions having a gradient of greater than 350% / μm.

7. some of the peaks are located within 20 nm of a maximum peak height relative to the ground plane, and those peaks are represented in the second portion of the Abbott-Firestone curve; the Abbott-Firestone curve includes a third vertical portion representing a peak portion located at a peak height between the ground plane and the maximum peak height. The article of claim 6.

8. The Abbott-Firestone curve is a fourth vertical portion representing an additional peak portion located at a peak height between the ground plane and the maximum peak height other than a height associated with the third vertical portion; further comprising The intermediate portion is a first intermediate portion disposed between the first portion and the third vertical portion; a second intermediate portion disposed between the third vertical portion and the fourth vertical portion; and a third intermediate portion disposed between the fourth vertical portion and the second portion; Including, The article of claim 7.

9. 9. The article of claim 8, wherein each of the first intermediate portion, the second intermediate portion, and the third intermediate portion is either (a) a segment of the Abbott-Firestone curve at least 50 nm in height having an average slope at least 50% / μm less than an adjacent vertical portion, or (b) an inflection point of the Abbott-Firestone curve.

10. The article is a transmission haze of 3.5% or less, and Sparkle less than 2.5% measured at 140 ppi, indicates, 4. The article of any one of claims 1 to 3, wherein the article has a first average modulation transfer function averaged over spatial frequencies of 1.67 cycles / mm, 4.11 cycles / mm, 7.33 cycles / mm, 10.38 cycles / mm, and 13.08 cycles / mm of at least 0.7 when the article is viewed at a viewing angle of 0° and light having a luminance of 45,000 lux is incident on the first major surface at an angle of incidence of 20°.

Images