Retroreflective article comprising multiple partially laminated layers

Abstract

A retroreflective article is disclosed, the retroreflective article comprising a binder layer and a plurality of retroreflective elements, each of which comprises transparent microspheres partially embedded in the binder layer. At least some of the retroreflective elements comprise a first partial laminate layer and a second partial laminate layer, which may be a reflective layer. A transfer article is also disclosed, the transfer article comprising a disposable carrier layer, wherein the retroreflective article can be removably arranged so that at least some of the transparent microspheres are in contact with the disposable carrier layer.

Description

Background Art

[0001] Retroreflective materials have been developed for a variety of applications. Such materials are often used, for example, as high-visibility trim materials in clothing to increase the wearer's visibility. For example, such materials are often added to clothing worn by firefighters, emergency rescue personnel, road workers, etc. Summary of the invention

[0002] In summary, a retroreflective article comprising a binder layer and a plurality of retroreflective elements is disclosed herein. Each retroreflective element comprises transparent microspheres partially embedded in the binder layer. At least some of the retroreflective elements comprise a first partial laminate layer and a second partial laminate layer. These and other aspects will become apparent in the following detailed description. However, in no event should this broad summary of the invention be construed as a limitation on subject matter that may be protected by the claims, whether such subject matter is presented in the claims of the initially filed application or in the claims of an amended application, or otherwise during the prosecution process. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Figure 1 is a side schematic cross-sectional view of an exemplary retroreflective article having a first exemplary partial laminate layer and a second exemplary partial laminate layer.

[0004] Figure 2 for Figure 1 An enlarged cross-sectional view of a portion of FIG. 1 , showing details of an exemplary local laminate layer.

[0005] Figure 3 Another exemplary partial laminate layer detail is shown for an enlarged cross-sectional view.

[0006] Figure 4 1 is an enlarged perspective view of a single transparent microsphere and a separation of a first exemplary partial laminate layer and a second exemplary partial laminate layer.

[0007] Figure 5 Schematic cross-sectional side view of a single transparent microsphere and separation of a first exemplary partial laminate layer and a second exemplary partial laminate layer.

[0008] Figure 6 is a schematic side cross-sectional view of an exemplary transfer article including an exemplary retroreflective article having a first exemplary partial laminate layer and a second exemplary partial laminate layer, wherein the transfer article is shown coupled to a substrate.

[0009] Figure 7 is a side schematic cross-sectional view of an exemplary method for locally laminating a layer to a portion of a protruding transparent microsphere.

[0010] Figure 8is a side schematic cross-sectional view of another exemplary method for locally laminating a layer to a portion of a protruding transparent microsphere.

[0011] Fig. 9 is a side schematic cross-sectional view of an exemplary intermediate article including a carrier layer carrying transparent microspheres having a first exemplary partial laminate layer and a second exemplary partial laminate layer disposed thereon.

[0012] Fig.10 The retroreflectivity of the comparative example is shown as a function of wavelength and angle of incidence.

[0013] Fig.11 The retroreflectivity as a function of wavelength and incident angle is shown for another comparative example.

[0014] Fig.12 The retroreflectivity of the working examples is shown as a function of wavelength and angle of incidence.

[0015] In the various figures, similar reference numerals represent similar elements. Some elements may exist in the same or equal multiples; in this case, one or more representative elements may be designated only by reference numerals, but it should be understood that such reference numerals apply to all such identical elements. Unless otherwise specified, all non-photographic illustrations and drawings in this document are not drawn to scale and are selected for the purpose of illustrating different embodiments of the present invention. Specifically, unless otherwise specified, the shapes, sizes, and other aspects of various items in the drawings are described only in exemplary terms, and the relationship between the sizes, shapes, relative curvatures, etc. of the various items should not be inferred from the drawings. (In fact, it should be understood from the discussion herein that the various layers and other items shown in the figures are idealized general representations.)

[0016] As used herein, terms such as "front," "forward," and the like refer to the side from which a retroreflective article is viewed (and thus the side from which light impinges upon the article to be retroreflected). Terms such as "rear," "rearward," and the like refer to the opposite side, such as the side to be attached to a garment. The term "lateral" refers to any direction perpendicular to the front-to-back direction of the article, and includes directions along both the length and width of the article. Figure 1 An exemplary article's front-to-back direction (fr) and an exemplary lateral direction (l) are indicated in FIG.

[0017] Terms such as disposed on, disposed over, disposed on top of, disposed between, disposed behind, disposed adjacent to, disposed in contact with, disposed proximate to, etc. do not require that a first entity (e.g., a layer) must be in direct contact with a second entity (e.g., a second layer) that is disposed on, disposed behind, disposed adjacent to, or disposed in contact with the first entity, for example. Rather, such terms are used for convenience of description and allow for the presence of additional entities (e.g., layers such as adhesive layers) or entities between such layers, as will be clear from the discussion herein.

[0018] By reflective is meant that an entity (e.g., a layer) is capable of reflecting "light"; in this context, "light" is defined to cover both the visible and infrared spectra. Thus, a reflective layer as defined herein may reflect at least some wavelengths of visible light, at least some wavelengths of infrared light, or both. In quantitative terms, a reflective layer (which may include multiple sublayers as discussed herein) is a layer of material that exhibits at least 25% reflectivity at least at a selected wavelength or within a selected wavelength range of between 380 nanometers (nm) and 1 millimeter (mm), between 400nm and 700nm (e.g., a typical visible light wavelength range), or between 700nm and 2500nm (e.g., a typical near infrared (IR) light wavelength range) in a spectral reflectance curve obtained at normal incidence. In many embodiments, the selected wavelength or range will be the wavelength or range of peak reflectance exhibited by the layer. In some embodiments, the reflective layer may exhibit at least 40%, 60%, 80%, or 90% reflectivity at a selected wavelength or within a selected wavelength range. In some embodiments, the reflective layer can exhibit a reflectivity of at least 40%, 60%, 80%, or 90% across the visible range, across the near infrared range, or in both ranges.

[0019] By layers of differing reflectivity is meant layers that exhibit at least a 10% difference in reflectivity at any selected wavelength or within any selected wavelength range (between 380 nm and 1 mm, between 400 nm and 700 nm, or between 700 nm and 2500 nm), as discussed in detail later herein.

[0020] By transparent is meant that an entity (e.g., a layer) transmits at least 50% of light at a selected wavelength or within a selected wavelength range between 380 nm and 1 mm, between 400 nm and 700 nm, or between 700 nm and 2500 nm. In some embodiments, a transparent entity may transmit at least 60%, 70%, 80%, or 90% of light at a selected wavelength or within a selected wavelength range. In some embodiments, a transparent entity may transmit at least 60%, 70%, 80%, or 90% of light throughout the visible light range, throughout the near infrared light range, or within both ranges. In some embodiments, a transparent entity may transmit at least 50% of light in the visible light spectrum and reflect at least 25% of light in the near infrared light spectrum. In some embodiments, a transparent entity may transmit at least 50% of light in the near IR spectrum and reflect at least 25% of light in the visible light spectrum. (It should therefore be understood that some layers (e.g., certain wavelength selective reflective dielectric stacks) may qualify as both reflective layers and transparent layers as defined herein.)

[0021] As used herein, as a modifier to a characteristic or attribute, unless otherwise specifically defined, the term "substantially" means a characteristic or attribute that would be readily recognizable by a person of ordinary skill, without requiring a high degree of approximation (e.g., within + / - 20% for a quantifiable characteristic). For angular orientation, the term "substantially" means within 10 degrees clockwise or counterclockwise. Unless otherwise specifically defined, the term "substantially" means within 5 degrees clockwise or counterclockwise. The term "substantially" means very highly approximated (e.g., within + / - 2% for a quantifiable characteristic; within + / - 2 degrees for an angular orientation); it should be understood that the phrase "at least substantially" includes the specific case of an "exact" match. However, even an "exact" match, or any other feature description using terms such as identical, equal, consistent, uniform, constant, etc., will be understood to be within ordinary tolerances, or within measurement errors applicable to the particular situation, rather than requiring an absolutely precise or exact match. The term "configured to" and similar terms are at least as restrictive as the term "adapted to," and require actual design intent to perform the specified function, not just the physical ability to perform such function. All references to numerical parameters (dimensions, ratios, etc.) herein are understood to be capable of being calculated (unless otherwise stated) using averages derived from multiple measurements of the parameters. Unless otherwise indicated, all averages referred to herein are number averages. DETAILED DESCRIPTION

[0022] Figure 1 A retroreflective article 1 is shown in an exemplary embodiment. Figure 1As shown, the article 1 includes a binder layer 10, which includes a plurality of retroreflective elements 20 spaced apart on the length and width of the front side of the binder layer 10. Each retroreflective element includes a transparent microsphere 21, which is partially embedded in the binder layer 10, so that the microsphere 21 is partially exposed and defines the front (viewing) side 2 of the article. Therefore, each transparent microsphere has an embedded (surface) area 25 disposed in the receiving cavity 11 of the binder layer 10 and an exposed area 24 exposed in front of the main front surface 14 of the binder layer 10. In some embodiments, the exposed area 24 of the microsphere 21 of the article 1 is exposed to the ambient atmosphere (e.g., air) in the final article used, rather than being covered, for example, with any kind of covering layer, etc. Such an article will be referred to as an exposed lens retroreflective article. In various embodiments, the microspheres may be partially embedded in the binder layer so that, on average, 15%, 20%, or 30% of the microsphere diameter to about 80%, 70%, 60%, or 50% of the microsphere diameter is embedded in the binder layer 10. In many embodiments, the microspheres may be partially embedded in the binder layer such that, on average, 50% to 80% of the diameter of the microspheres are embedded within the binder layer 10 .

[0023] Retroreflective element 20 will include at least one reflective layer disposed behind transparent microspheres 21, such as between transparent microspheres 21 and binder layer 10. Microspheres 21 and reflective layer together return a significant amount of incident light to a light source projected on front side 2 of article 1. That is, at least some of the light striking front side 2 of the retroreflective article enters and passes through microspheres 21 and is reflected by at least one reflective layer to re-enter microspheres 21 again, such that the light is directed back toward the light source. In many embodiments, there may be two reflective layers; in some embodiments, one or both such layers may take the form of a localized laminate layer, as discussed in detail herein.

[0024] Retroreflective articles 1 as disclosed herein will include at least some retroreflective elements 20, each of which includes transparent microspheres 21, which carry a first partial laminate layer 30 and a second partial laminate layer 530, such as Figure 1As shown in the exemplary embodiments in. In many embodiments, the first partial laminate layer 30 and / or the second partial laminate layer 530 can be a reflective layer, as discussed in detail later herein. However, in some embodiments, at least one of the first partial laminate layer and the second partial laminate layer may not be reflective. On the contrary, in some embodiments, the laminate layer may play some other role. For example, such a layer may provide a peeling surface to prevent some other layers from bonding to the area of ​​the microspheres covered by the peeling layer, as discussed later herein. In such embodiments, some other layers may be provided to serve as reflective layers, for example, by conventional vapor coating of a metal layer or dielectric stack on transparent microspheres, by printing a reflective layer on the microspheres, etc. In some embodiments, the reflective layer can be provided in the form of a second reflective layer, such as by including reflective particles in the binder layer of the retroreflective article, as discussed later herein.

[0025] In view of the fact that the local laminated layer may not necessarily be used only (or not at all) as a reflective layer, such a layer will be referred to herein as a "functional" layer, and it should be understood that in many embodiments, the function of such a layer will be to serve as a reflective layer. The so-called local laminated layer refers to such a functional layer, which is prefabricated into an article (for example, prefabricated as a part of a film-like or sheet-like structure), and then the local area of ​​the prefabricated layer is physically transferred (i.e., laminated) to a part of a transparent microsphere, as discussed in detail later in this article. The so-called first local laminated layer and the second local laminated layer refer to the first layer being set to at least some of the microspheres in the first lamination process, and then the second layer being set to at least some of the microspheres of the same microspheres in the second subsequent lamination process. That is, in this case, the terms "first" and "second" specifically mean a sequential lamination process. Performing two sequential lamination processes (together with appropriately controlling the lamination process as disclosed herein) can produce a first local laminated layer and a second local laminated layer, which can be identified by any of various geometric, structural, optical or other characteristics, as discussed in detail herein.

[0026] The exemplary first partial laminate layer 30 and the second partial laminate layer 530 are Figure 1 is shown in a general idealized manner. Figure 1 As shown in the exemplary embodiment of FIG. 5 , in some embodiments, at least a portion 534 of the second partial laminate layer 530 can be arranged "parallel" to the first partial laminate layer 30. The term parallel means that a portion of the second layer 530 (e.g., Figure 1The portion 534 in the second layer 530 can be reached by light rays shining on the retroreflective elements from the front without these rays having to pass through any portion of the first layer 30. In some embodiments, the entire second layer 530 can be composed of the portion 534 that is parallel to the first layer 30; in other embodiments, only a portion of the second layer can be parallel to the first layer, as will be clear from the discussion below.

[0027] In some embodiments, at least a portion 535 of the second partial laminate layer 530 can be arranged "in series" with the first partial laminate layer 30. The term in series means that a portion of the second layer 530 (e.g., Figure 1 The portion 535 of the particular second layer, represented as 530' in the figure, is arranged roughly behind the first layer 30 so that light shining on the retroreflective element from the front must pass through the first layer 30 to reach the "in-line" portion 535 of the second layer 530.

[0028] Thus, in at least some embodiments, for at least some of the retroreflective elements 20 that include a first partial laminate layer 30 and a second partial laminate layer 530, the first area of ​​embedded regions 25 of transparent microspheres covered by the first layer 30 and the second area of ​​embedded regions 25 of microspheres covered by the second layer 530 will be non-coextensive. This means that the second area occupied by the second layer 530 does not share exactly the same size and shape as the first area occupied by the first layer 30.

[0029] In some cases, no portion of the second partial laminate layer 530 may be arranged in series with the first partial laminate layer. In other words, for some retroreflective elements 20, such as Figure 1 The portion 535 shown in the second partial laminate layer 530' in FIG. 5 may not exist. For example, in some embodiments, the second partial laminate layer 530 may be provided as a spherical segment (e.g., Figure 1 , Figure 4 and Figure 5 534), for example, Figure 4 and Figure 5 The second layer 530 is generally arranged in the manner shown, without any significant portion of the second layer 530 being arranged behind (in series with) any portion of the first layer 30. In other embodiments, a significant portion 535 of the second layer 530 may be Figure 1 The second layer 530, which includes the serial portion 535, may also include a significant portion 534 that is parallel to the first layer 30, such as from Figure 1 Obvious.

[0030] In summary therefore, in some cases, the second layer 530 may be partially laminated such that it exists only as a bulbous segment that at least partially surrounds the first partially laminated layer but does not overlap the first layer to any significant extent backwards. Figure 1 , Figure 4 and Figure 5 In other cases, the second layer may be partially laminated so that a portion 535 thereof overlaps the first layer backward, such as Figure 1 An exemplary general representation of a particular second layer is shown in FIG. 5 , which is labeled 530 ′.

[0031] Regardless of whether the second partial laminate layer 530 includes a portion 535 in series with the first partial laminate layer 30, in many embodiments, the second layer 530 will include a portion 534 that is parallel to the first layer 30 and forms an at least partially spherical segment that at least partially surrounds the first layer. Figure 4 and Figure 5 An exemplary general representation is shown in an enlarged, isolated view of Figure 4 and Figure 5 In a particular arrangement of the second layer 530, the portion 534 of the second layer 530 is a complete spherical segment rather than a partial spherical segment; that is, the portion 534 completely surrounds the first layer 30. In other embodiments, the second layer 530 may include parallel portions 534 that only partially circumscribe the first layer 30. When viewed along the front-to-back axis of the transparent microsphere, the second layer portion 534 that is a complete spherical segment will resemble a complete, uninterrupted torus; when viewed in this manner, the second layer portion 534 that is a partial spherical segment will resemble a partial torus. It should be understood that, for convenience, the term spherical segment is used to refer to the second layer that generally surrounds the first layer when viewed in this manner; this does not mean that the spherical segment must take the form of a perfect torus, nor does it mean that the radially outer perimeter or radially inner perimeter of such a segment need to take the shape of a perfect circle.

[0032] An arrangement in which the second layer 530 includes parallel portions 534 can be achieved by two general methods. In one such method, the second layer is partially laminated so that the second layer includes portions 535 that remain in place behind the first layer (i.e., with Figure 1 The second layer 530' is generally formed in a manner similar to that of the first layer 30. Such a second lamination process (discussed later herein) will be referred to herein as a full transfer process. Such a method will produce a second layer 530 having at least a portion 535 whose front surface 532 is in contact with the back surface 33 of the first layer 30. The second layer may also have another portion 534 whose front surface 532 is in contact with the back surface of the transparent microspheres, or with the back surface 53 of the adhesive layer / intermediate layer 50 that may be present on the transparent microspheres.

[0033] In another such method, the second layer is partially laminated so that the second layer does not include a portion that remains in place behind the first layer (i.e., in the general manner of the second layer 530, such as Figure 4 and Figure 5 ). Such a second lamination process (also discussed later herein) will be referred to herein as a torus transfer process. Of course, in any realistic lamination process, a mixture of these two arrangements may be produced. That is, from the discussion later herein regarding the method of forming the first partial lamination layer and the second partial lamination layer, it will be apparent that the specific shapes of the first and second layers, the coverage of the microspheres, etc. may vary to some extent due to the statistical nature of the lamination process. However, the discussion herein will also make it clear that the lamination parameters and conditions can be varied to tailor the average conditions of the first and second layers to a desired range.

[0034] Various parameters and lamination process conditions may be selected to affect, for example, the location of the transparent microspheres occupied by the first partial lamination layer 30 and the second partial lamination layer 530, the relative sizes of the first and second layers, etc. Such an arrangement may be relative to Figure 4 and Figure 5 The exemplary arrangements shown in the idealized general representation are discussed herein and may be characterized, for example, by the angular arc occupied by each layer.

[0035] In various embodiments, the first layer 30 may occupy an angle arc α (measured from the secondary outer edge 31 of the layer 30, measured from the vertex "V" at the geometric center of the microsphere, such as 135 degrees, 90 degrees, 70 degrees, 50 degrees, 30 degrees, 20 degrees, or 10 degrees, for example. Figure 5 In another embodiment, the first layer 30 may occupy an angle arc α of at least 5 degrees, 15 degrees, 25 degrees, 35 degrees, 45 degrees, 55 degrees, 65 degrees, or 80 degrees. By way of specific example, Figure 5 The first layer 30 shown occupies an angular arc α of approximately 80 degrees to 85 degrees. In some embodiments, such a first layer 30 can be at least approximately, substantially, or essentially centered on the front-to-back centerline of the transparent microsphere (i.e., centered on the rearmost point or "north pole" of the microsphere, such as Figure 4 and Figure 5 ).

[0036] The second layer 530 may thus comprise a portion 534 parallel to the first layer 30, in the form of, for example, a spherical segment arranged radially outside the first layer 30 and at least partially circumscribing the first layer. The second layer may occupy, for example, an angular arc β greater than 10, 20, 30, 50, 60, 70, 90, 110, 130, 150 or 170 degrees. Such an angular arc is measured from the periphery of the second layer (i.e., from the secondary outer edge 531 of the layer 530), and regardless of whether the second layer comprises only the spherical segment portion 534 or also comprises a serial portion 535 overlapping the first layer. By way of specific example, Figure 5 The illustrated second layer 530 occupies an angular arc β of approximately 125 degrees to 135 degrees. In some embodiments, such a second layer 530 will be at least approximately, substantially, or essentially centered on the rearmost point of the transparent microspheres in a manner similar to the first layer 30 .

[0037] Methods for evaluating angular arc (and other related parameters, such as the percentage of area coverage exhibited by a layer) are presented in detail in U.S. Provisional Patent Application 62 / 739506 and PCT International Patent Application No. US2018 / 057553, both of which are incorporated herein by reference in their entirety. Such methods are also discussed in U.S. Provisional Patent Application 62 / 739489 and PCT International Patent Application No. US2018 / 057561, both of which are incorporated herein by reference in their entirety. It should be understood that such parameters can be determined at least semi-quantitatively by using micrographs of the general type found in, for example, the '489 and '561 patent applications.

[0038] In some particularly useful embodiments, the first layer 30 may be present in a relatively small area compared to the area occupied by the second layer 530, and may be located at or near the rearmost point of the transparent microsphere in the manner described above. In certain embodiments, the first layer may coincide with the front-to-back centerline of the transparent microsphere (meaning that the centerline passes through some portion of the first layer), such as Figure 1 , Figure 4 and Figure 5 As shown in the exemplary embodiment of . For convenience, such a first layer is sometimes referred to herein as a "polarizing cover" layer. Such a polarizing cover first layer may be partially (e.g., completely) surrounded by a second layer (e.g., the second layer may occupy an angular arc greater than the angular arc of the first layer). Such an arrangement may impart specific advantages as discussed in detail herein. In some specific embodiments, the polarizing cover first layer may occupy an angular arc of no more than 40 degrees, and the second layer may include parallel segments occupying an angular arc of at least 80 degrees. In other specific embodiments, the polarizing cover first layer may occupy an angular arc of at least 80 degrees, wherein the second layer includes parallel segments occupying an angular arc of greater than 90 degrees.

[0039] In some specific embodiments, the first partial laminate layer 30 and the second partial laminate layer 530 may occupy, on average, at least approximately, substantially, or essentially the same angular arc. For example, in some embodiments, the first layer and the second layer (which may be identical to each other in all respects, or may be different from each other in at least one respect) may be partially laminated so that the two layers occupy approximately, substantially, or essentially the same area of ​​the transparent microsphere. It should be understood that in any actual production process, statistical variations may occur even for the first and second layers for the same nominal area coverage and / or angular arc.

[0040] In many embodiments, either or both of the first partial laminate layer 30 and the second partial laminate layer 530 can be a reflective layer as defined herein. In various embodiments, any such reflective layer can exhibit a reflectivity of at least 40%, 60%, 80%, or 90% at some wavelengths between 380nm and 2500nm. In some embodiments, the first layer 30 and the second layer 530 can be at least approximately, substantially, or essentially identical to each other in terms of their reflective properties. For example, they can both be vapor deposited silver layers, they can both be dielectric stacks including substantially the same sublayer groups, and the like. In this case, performing two consecutive lamination operations can be used, for example, to improve the overall uniformity of the resulting retroreflective article, to prepare a retroreflective article that exhibits enhanced retroreflectivity at larger incident angles, and the like.

[0041] However, in many useful embodiments, the reflective properties of the first layer 30 and the second layer 530 can be different. For example, in some embodiments, the second layer 530 can be at least substantially reflective, while the first layer 30 can be non-reflective, such as transparent as previously defined herein. If the first non-reflective layer 30 is present in a polarizing cover configuration as described above, and is circumscribed on at least some sides by portions 534 of the second reflective layer 530, a retroreflective element with unique properties can be produced. For example, a retroreflective element (and a retroreflective article comprising a collection of such elements) comprising a visually transparent first layer 30 in a polarizing cover configuration and a visually reflective second layer 530 in a spherical segment configuration can exhibit visible light retroreflectivity that, at least at some wavelengths, actually increases as the angle of incidence of the incident light increases (i.e., greater grazing angles).

[0042] Thus, in some embodiments, the first partial laminate layer 30 can be used primarily to passivate the polarizing cover region of the transparent microspheres so that the second partial laminate reflective layer will not bond to the polarizing cover region. This can allow the creation of a retroreflective element with a second reflective layer that is a pure spherical segment (rather than including a portion in series with a transparent polarizing cover first layer) and has a non-reflective (e.g., transparent) polarizing cover region. (As discussed later herein, lamination conditions can also be manipulated to promote or discourage this from occurring.) In various embodiments, such a first layer 30 can exhibit a total transmittance of at least 85%, 90%, or 95% from 380nm to 2500nm.

[0043] In some embodiments, the reflectivity of the first partial laminate layer 30 and the second partial laminate layer 530 may be different. As defined above, this means that the layer exhibits a reflectivity difference of at least 10% at any selected wavelength or in any selected wavelength range (between 380nm and 1mm, between 400nm and 700nm, or between 700nm and 2500nm). In various embodiments, the first layer and the second layer may exhibit a reflectivity difference of at least 20%, 40%, 60%, 80%, or 90% at a selected wavelength or in a selected wavelength range between 380nm and 1mm, between 400nm and 700nm, or between 700nm and 2500nm. The percentage difference is an absolute value and is evaluated at the wavelength of the maximum difference in reflectivity. Typically, the maximum percentage difference in reflectance may occur at the wavelength of peak reflectance of one of the layers. By way of specific example, if one layer exhibits 70% reflectivity at a certain wavelength (eg, the wavelength of peak reflection) and another layer exhibits 40% reflectivity at the same wavelength, the reflectivity of the two layers differs by 30%.

[0044] For these and any other evaluations presented herein that require the measurement of reflectivity, it is provided that even if layers present on microspheres, for example, are too small to directly measure their reflectivity in situ in a retroreflective article, these definitions will apply to measuring layers of these same materials in a form that allows their reflectivity to be evaluated. Of course, for many such layers, reliable estimates of reflectivity can be obtained from retroreflectivity measurements of retroreflective articles having these layers.

[0045] In some embodiments, both the first partial laminate layer 30 and the second partial laminate layer 530 can be reflective, but their reflective properties can differ at least to some extent. In some embodiments, at least one of the reflective layers can be wavelength selective; that is, a layer that preferentially reflects light of a specific (e.g., predetermined) wavelength as defined and described below. In some such embodiments, one of the reflective layers (e.g., the second layer 530) can be wavelength selective, while the other reflective layer (e.g., the first layer 30) is non-wavelength selective. A non-wavelength selective reflective layer is any reflective layer that does not conform to the wavelength selective layer defined herein. In many embodiments, the non-wavelength selective layer can be a broad spectrum high reflective layer composed of, for example, a silver or aluminum layer. In other embodiments, both the first layer and the second layer can be wavelength selective reflective layers.

[0046] By way of specific example, the first layer 30 (e.g., arranged in a polarizing cover arrangement) can be a wavelength selective reflective layer that is configured to preferentially reflect light somewhere within the near infrared (IR) spectrum (e.g., covering wavelengths of about 700nm-2500nm). At the same time, the second layer 530 (e.g., arranged in a spherical segment) can be a wavelength selective reflective layer that is configured to preferentially reflect light somewhere within the visible spectrum (e.g., covering wavelengths of about 400nm-700nm). Thus, a retroreflective article can be produced that preferentially reflects near infrared light at relatively low (e.g., frontal) incident angles of, for example, 0 to 5 degrees; and, at relatively large incident angles (e.g., 30 degrees), preferentially reflects visible light. One arrangement that achieves this general type of behavior is shown in Working Example 1 of the working examples herein. In other embodiments, the wavelength selectivity of the first and second layers can be switched to produce a retroreflective article that preferentially reflects visible light at low incident angles and preferentially reflects near infrared light at high incident angles. And, of course, arrangements may be provided in which the first layer and the second layer reflect preferentially at different wavelengths in the visible range or in which they reflect preferentially at different wavelengths in the infrared range.

[0047] By preferential reflection is meant that at a particular wavelength in the range of 380 nm to 1 mm, the layer exhibits a peak reflectivity that is at least 20% greater than the reflectivity exhibited at some other wavelength in the range, where the difference is expressed in absolute value. By way of specific example, a wavelength selective reflective layer exhibiting a peak reflectivity of 80% at 600 nm and a reflectivity of 20% at 900 nm exhibits a peak reflectivity that is 60% greater than the reflectivity at 900 nm. In various embodiments, the wavelength selective reflective layer may exhibit a peak reflectivity that is at least 30%, 40%, 50%, 60%, 70%, 80%, or 90% greater than the reflectivity exhibited at some other wavelengths.

[0048] In various embodiments, the first layer 30 and the second layer 530 can be configured to exhibit peak reflection at wavelengths that differ from each other by a desired amount. As described above, in some embodiments, one layer may preferentially provide reflection in the visible range, while another layer may preferentially provide reflection in the near infrared range. Alternatively, in some embodiments, one layer may preferentially provide reflection in a portion of the visible light range, while another layer may preferentially provide reflection in another different portion of the visible light range. In some embodiments, one or both layers may be used as, for example, a bandpass filter, a notch filter, etc. In various embodiments, the first layer and the second layer may be selected to exhibit a corresponding peak reflection wavelength that differs by at least 50nm, 100nm, 200nm, 400nm, or 600nm. In other embodiments, the first layer and the second layer may be selected to exhibit a corresponding peak reflection wavelength that differs by no more than 10000nm, 5000nm, 2000nm, 1000nm, 800nm, 700nm, 500nm, or 300nm.

[0049] In some embodiments, such retroreflective elements (and retroreflective articles including collections of such elements) can exhibit retroreflectivity that, at least at some wavelengths, does not decrease as sharply as conventional retroreflective articles with increasing angle of incidence of incident light. In fact, such elements and articles can exhibit retroreflectivity that, at least at some wavelengths, is actually greater at high angles of incidence (e.g., measured at 30 degrees of incident angle of light) than at low, more "frontal" angles of incidence (e.g., measured at 5 degrees of incident angle). Such an arrangement is in contrast to conventional retroreflective articles and offers the possibility of many interesting uses. One such arrangement that achieves this type of behavior is demonstrated in Working Example 1 of the Working Examples herein.

[0050] The above discussion has made it clear that the first layer and the second layer can be any suitable layer having any desired configuration, characteristics or functions. For example, in some embodiments, the first layer or the second layer can be or include an optical delay plate, which means a layer (or sublayer) that selectively slows down one of the orthogonal components of light to change its polarization. In some embodiments, such an optical delay plate can be constructed as a quarter-wave delay plate, which has a delay amount of λ / 4 for a certain wavelength λ of interest. For light of a given wavelength, a quarter-wave delay plate will change the light of that wavelength from circularly polarized light to linearly polarized light, and vice versa. Optical delay plates are described and discussed in detail in U.S. Provisional Patent Application 62 / 610180 and PCT International Patent Application No. IB2018 / 058406, both of which are incorporated herein by reference in their entirety.

[0051] In some embodiments, the first local laminate layer and / or the second local laminate layer may include a colorant so as to become a color layer of the general type described in detail later herein. Generally speaking, for any purpose, the first local laminate layer and the second local laminate layer may include any desired type, composition and number of (sub) layers formed in any desired order or configuration. It is not necessary to require any such sublayer for optical purposes (but in some cases, it may be necessary that the sublayer does not detract from the optical function of some other layers). In various embodiments, as discussed herein, the sublayer may be a brittle layer, an adhesion promotion (or adhesion minimization, i.e., passivation) layer, a color layer or an optical delay layer. The first local laminate layer and / or the second local laminate layer may include any desired combination of any such sublayers (e.g., in combination with a reflective layer). Although in many embodiments, the first local laminate layer and the second local laminate layer may be different in at least one aspect (e.g., in the composition, quantity and / or type, thickness and / or any optical properties such as reflectivity, absorptivity or transparency of the sublayer), in some embodiments, the first local laminate layer and the second local laminate layer may be the same as each other.

[0052] It should be understood that the reflectivity of the first layer and the second layer can be constructed in a variety of ways. For example, the above-mentioned general arrangement can be reversed to provide a polarization cover first layer that preferentially reflects visible light and a spherical section that preferentially reflects near-infrared light. In a more specific example, the first layer or the second layer can be, for example, a metal layer (e.g., a vapor coating layer of silver, aluminum, etc.) that exhibits substantially non-preferential reflection (i.e., does not vary significantly with wavelength). Then, the other layer can be a dielectric stack (e.g., including alternating sublayers of high refractive index materials such as metal oxides and low refractive index organic polymer materials) that selectively exhibits a peak (maximum) reflection wavelength within a desired range. Alternatively, the first layer can be a first dielectric stack, wherein the high refractive index sublayer and the low refractive index sublayer are arranged so that the first layer selectively exhibits a peak reflection wavelength within a first range, and the second layer is a second dielectric stack, wherein the high refractive index sublayer and the low refractive index sublayer are arranged so that the second layer selectively exhibits a peak reflection wavelength within a second range different from the first range.

[0053] The dielectric stack of alternating high refractive index sublayers and low refractive index sublayers can be customized in a variety of different configurations to provide the desired reflective selectivity. All such possible arrangements will not be discussed herein, but these arrangements will be well known and available to those of ordinary skill. Various exemplary arrangements are provided, for example, in U.S. Patent Nos. 3,700,305 and 6,172,810, both of which are incorporated herein by reference in their entirety. Specific exemplary arrangements (e.g., a dielectric stack with a total thickness in the range of 260 nm-270 nm and a wavelength of peak reflectivity in the range of 550 nm-600 nm; and, a dielectric stack with a total thickness in the range of 780 nm-790 nm and a wavelength of peak reflectivity in the range of about 850 nm-950 nm) are disclosed in the working examples herein.

[0054] In various embodiments, the first and second local laminated layers may be configured to exhibit peak reflection at wavelengths that differ from each other by a desired amount. As described above, in some embodiments, one local laminated layer may preferentially provide reflection in the visible range, while another local laminated layer may preferentially provide reflection in the near infrared range. Alternatively, in some embodiments, one layer may preferentially provide reflection in a portion of the visible light range, while another layer may preferentially provide reflection in another different portion of the visible light range. In some embodiments, one or both layers may be used as, for example, a bandpass filter, a notch filter, etc. In various embodiments, the first and second local laminated layers may be selected to, for example, exhibit corresponding peak reflection wavelengths that differ by at least 50nm, 100nm, 200nm, 400nm, or 600nm. In other embodiments, the first and second layers may be selected to exhibit corresponding peak reflection wavelengths that differ by no more than 1000nm, 800nm, 700nm, 500nm, or 300nm.

[0055] In some embodiments, the first partial laminate layer and the second partial laminate layer may be configured so that at at least one wavelength between 400nm and 1400nm, the retroreflective article exhibits a percentage of retroreflection greater than the percentage of retroreflection exhibited at an angle of incidence of 5 degrees at an angle of incidence of at least 1%, 2%, 3%, 4% or 5%. In other embodiments, such performance may occur at least at a wavelength between 400nm and 750nm. In such measurements, the percentage of the greater increment is in terms of the absolute difference in the retroreflectivity value rather than the ratio to one of the values. For example, an article that exhibits a percentage retroreflectivity of 5% at an angle of incidence of 30 degrees and a percentage retroreflectivity of 2% at an angle of incidence of 5 degrees will be understood to exhibit a 30-degree retroreflectivity greater than the 5-degree retroreflectivity, with an increment of 3% (not 150%).

[0056] It should therefore be understood that the ability to arrange first and second partial laminate layers in various geometric configurations disclosed herein (e.g., including a "polarizing cover" first layer occupying selected areas of the microspheres, and a "spherical segment" second layer at least partially surrounding the polarizing cover first layer) and the ability to select the reflectivity of the first and second layers provide a tool that allows the production of retroreflective articles having a variety of properties, retroreflective performance, etc.

[0057] As a specific, non-limiting example, a retroreflective article may be prepared with a polarizing cover first layer reflector (occupying an angular arc of, for example, 40 degrees up to 90 degrees on average) that is highly reflective at all relevant wavelengths (e.g., composed of vapor-coated silver). The article may have a spherical segment second layer reflector that is a dielectric stack selected to exhibit fairly good reflectivity at some visible wavelengths, but is also transparent (and specifically, non-absorbing) for at least some wavelengths of visible light. In such examples, the second layer reflector may exist as a spherical segment that extends from an inner boundary located approximately at the outer perimeter of the first layer reflector and occupies an angular arc of at least 2 degrees, 5 degrees, 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, or 60 degrees greater than the angular arc of the first layer reflector.

[0058] Due to the high reflectivity of the first polarizing cover layer at all visible wavelengths, articles of this general type can exhibit very good retroreflectivity for "front" visible light. The dielectric stack second layer can provide sufficient visible light retroreflectivity at offset angles (e.g., at angles of incidence up to 40 degrees) to allow the retroreflective article to meet any of a variety of performance standards (e.g., the "32-angle" retroreflectivity standard, where retroreflectivity is measured at various angles of incidence and observation angles, as will be familiar to those skilled in the art) in combination with the "front" performance. At the same time, the dielectric stack second layer can be sufficiently transparent to allow the color of the binder layer (described later herein) of the retroreflective article to be visible through the microspheres in ambient light. In other words, the arrangements disclosed herein can allow the production of retroreflective articles that can pass any of a variety of retroreflective performance tests while still allowing the article's true color (e.g., fluorescent yellow, as imparted by the colorant in the binder layer) to be visible in ambient light. One such arrangement that achieves this general type of behavior is demonstrated in Working Example 2 of the Working Examples herein.

[0059] Thus, it will be appreciated by those of ordinary skill that, in some embodiments, the arrangements disclosed herein may allow a highly reflective layer (such as silver) to be present only in a relatively small area (e.g., polarizing cover) configuration, such that the layer provides excellent front retroreflection while not imparting an overall gray or "fading" color under ambient light, which typically occurs when such a reflective layer is present over a large area of ​​the transparent microspheres. A spherical segment second reflective layer (e.g., composed of a dielectric stack) may then be included to at least partially compensate for the absence of the highly reflective layer at high angles of incidence. Thus, enhanced color fidelity or vividness may be provided under ambient light while also achieving excellent retroreflective performance. It will therefore be appreciated that the arrangements disclosed herein allow designers of retroreflective articles to operate in a design space in which both the retroreflective performance of the article and the color / appearance of ambient light may be manipulated. However, it should be emphasized that the above discussion and specific configurations are merely exemplary, and the general arrangements disclosed herein may allow for the manufacture of many useful articles (e.g., for purposes of machine vision, etc.) that do not necessarily require or provide, for example, enhanced color fidelity. Arrangements, structures and articles that can be made by the methods disclosed herein and their potential advantages are discussed in U.S. Provisional Patent Application No. 62 / 838,580, entitled "RETROREFLECTIVE ARTICLE COMPRISING MULTIPLE LAYERS THAT DIFFER IN REFLECTIVITY," filed on the same day as this document, attorney docket No. 81911US002, which is incorporated herein by reference in its entirety.

[0060] The following discussion is described in terms of a single layer (eg, a single reflective layer 30), but should be understood to apply to partial lamination of both first and second layers, as disclosed herein.

[0061] In some embodiments, the partially laminated layer will be derived from a multilayer "transfer stack" that includes one or more additional layers in addition to the functional (e.g., reflective) layer. The additional layer or layers may facilitate the transfer of the functional layer to the transparent microspheres, as discussed in detail later herein. In various embodiments, some such additional layers may remain as part of the resulting retroreflective article (and thus may be referred to as sublayers of the partial transfer layer), and some may be sacrificial layers that do not remain as part of the resulting retroreflective article. For example, in some embodiments, the partially laminated reflective layer 30 may be a multilayer structure including a reflective layer 301 and additional (sub)layers (e.g., an embrittlement layer 302 and / or a selective bonding layer 303), such as Figure 2 and Figure 3 Such additional layers and their reasons for use are described in detail later in this article.

[0062] Thus, according to the terminology used herein, the "reflective" layer 30 includes the reflective layer 301 and may include other layers (e.g., transparent layers) such as an embrittlement layer 302 and / or a selective bonding layer 303. The term "reflective layer" refers to the particular layer 301 (e.g., a metal layer) of the reflective layer 30 that performs the actual reflection of light (noting that in some embodiments, the layer 301 itself may include sub-layers, such as in the case where the reflective layer 301 is a dielectric stack).

[0063] exist Figure 2 In embodiments of the type shown, reflective layer 30 may include selective bonding layer 303 positioned behind reflective layer 301 (such that a rear major surface of selective bonding layer 303 provides rear surface 33 of reflective layer 30); and, reflective layer may include embrittlement layer 302 in front of reflective layer 301 (such that a front major surface of embrittlement layer 302 provides front surface 32 of reflective layer 30). Figure 3 In embodiments of the type shown, these arrangements may be reversed, with the selective bonding layer 303 being located in front of the reflective layer 301 and the embrittled layer 302 being located behind the reflective layer 301. Any such additional layer (or layers) present in the retroreflective light path (e.g., Figure 2 Layer 302 and Figure 3 The layer 303 in the passageway will be constructed so as not to unduly interfere with the passage of light from the passageway. For example, such a layer may be transparent.

[0064] The term "lamination" refers to an arrangement achieved by obtaining a functional (e.g., reflective) layer as a prefabricated entity (e.g., a macroscopically reflective sheet or film-like article) and then physically transferring (laminating) a localized area of ​​the prefabricated functional layer to the protruding area 25 of the carrier-bearing microsphere 21. For example, the laminated reflective layer is thus distinguished from a reflective layer obtained by depositing a precursor onto transparent microspheres (e.g., by printing silver ink) and then curing the precursor to form a reflective layer. The laminated reflective layer is also distinguished from a reflective layer formed by depositing tiny material packages onto transparent microspheres to build up a reflective layer (such as the conventionally performed vapor deposition of metals onto transparent microspheres).

[0065] To perform such lamination, a multilayer transfer stack including a functional (e.g., reflective) layer 30 may be brought into close proximity with a protruding region 25 of a transparent microsphere 21 disposed on a temporary carrier 110 such that a localized region of the functional layer contacts at least a portion of an adhesive layer 50 present on at least a portion of the protruding region 25 of the microsphere. The localized region of the functional layer is then physically transferred to and bonded to the portion of the adhesive layer, thereby bonding the localized region of the reflective layer to a region 28 of the protruding region 25 of the microsphere. (This will form a Fig. 9) When the binder layer is formed as described in detail later herein, the raised areas 25 of the microspheres subsequently become embedded areas of the microspheres, also as discussed in detail later herein.

[0066] In the localized lamination process defined herein, a localized region of a preformed functional (e.g., reflective) layer is transferred to a portion of a protruding region of a transparent microsphere. In the process, the localized region of the functional layer is separated (detached) from the region of the functional layer that previously (in the preformed layer before lamination) laterally surrounds the transferred region. The laterally surrounding region of the functional layer from which the localized region is separated is not transferred to the microsphere (or any part of the resulting article), but is removed from the vicinity of the microsphere (e.g., together with other sacrificial layers of the multilayer transfer stack). Thus, the locally laminated reflective layer is a "microscopic" laminated layer that is distinguished from the reflective layer, which is obtained by large-scale lamination to a substrate without any laminated portion of the reflective layer being separated from other regions of the reflective layer. The detachment of the localized laminated regions of the functional layer from the laterally surrounding regions of their respective functional layers is not governed by any predetermined weak line in the functional layer. Instead, the detachment is the result of the localized deformation that the localized region of the functional layer undergoes when it is forced to conform to the surface of the microsphere.

[0067] In this lamination process, the localized area of ​​the functional layer transferred to the microspheres will be peeled (delaminated) from the other one or more layers of the multilayer transfer stack adjacent to the localized area, as will be clear from the discussion later in this article. This can be facilitated by providing a peeling interface in the multilayer transfer stack. In many convenient embodiments, this peeling interface can be provided by the major surface of the peeling layer present in the transfer stack. In some embodiments, the peeling layer can be in direct contact with the major surface of the functional layer; in such cases, the peeling interface will be the interface between the major surface of the functional layer and the major surface of the peeling layer. However, in many embodiments, at least one additional layer may be present between the functional layer and the peeling layer; in such cases, the peeling interface will be the interface between the major surface of the additional layer and the major surface of the peeling layer. In some embodiments, the additional layer will be a selective bonding layer that exhibits differential bonding / peeling on its two major surfaces. For example, one major surface of the layer can be non-peelably bonded to the major surface of the functional layer, while the opposite major surface of the layer can be peelably bonded to the major surface of the peeling layer to form a peeling interface, as discussed in detail later in this article.

[0068] In some embodiments, the release layer can be a sacrificial layer that is not transferred to or retained in the final retroreflective article and can therefore be removed and recycled, reused or disposed of (thus, in Figure 2 or Figure 3In some embodiments, the selective adhesive layer 303 may remain in the final retroreflective article, such as Figure 2 and Figure 3 In some embodiments, the multilayer transfer stack may optionally include an embrittlement layer that enhances the ability of a localized region of the functional layer to break away from regions of the functional layer that previously laterally surround the functional layer. In some embodiments, the embrittlement layer 302 remains in the final retroreflective article, such as Figure 2 and Figure 3 An exemplary design is shown in FIG.

[0069] U.S. Provisional Patent Application 62 / 478,992 and International Application Publication No. 2018 / 178802 describe transfer stacks (referred to as transfer articles) that can be used for laminating various "functional" layers, and both applications are incorporated herein by reference in their entirety. It should be understood that the reflective layer as described herein corresponds to a specific type of "functional" layer described in the '992 application. The '992 application also describes compositions (e.g., acrylate compositions) that are particularly suitable for use as selective adhesive layers. Local lamination of reflective layers and the use of multilayer transfer stacks to provide such layers are discussed in detail in U.S. Provisional Patent Application 62 / 578,343 (e.g., in Example 2.3 including Example 2.3.1-2.3.3 and Example 2.4 including Example 2.4.1-2.4.5), which is incorporated herein by reference in its entirety. Additional details and discussions are provided in U.S. Provisional Patent Application 62 / 739506 and PCT International Patent Application No. US2018 / 057553, both of which are incorporated herein by reference in their entirety.

[0070] The following discussion is described in terms of a single layer (e.g., a single reflective layer), but should be understood to apply to a partially laminated first layer and a second layer. Although the following discussion may refer to a reflective layer, they will also be understood to apply to a non-reflective partially laminated functional layer, for example, provided for the purpose of passivating an area of ​​transparent microspheres.

[0071] The partially laminated layers as defined and described herein will be identifiable and will be distinguished from other layers (e.g., from reflective layers that are not partially laminated). The partially laminated reflective layers will be distinguished from conventional continuous reflective layers by the presence of the partially laminated layers as a plurality of discontinuous discrete entities. In some embodiments, when viewed along the front-to-back axis of the retroreflective article, many (e.g., greater than 60%, 80%, 90%, or 95%) of such partially laminated layers may each exhibit a continuous area, e.g., less than 0.5, 0.2, 0.1, 0.05, or 0.01 square millimeters. This will be distinguished from, for example, retroreflective articles that include conventional reflective layers (e.g., vapor-coated metal layers), which may be continuous over a macroscopic area, e.g., several square millimeters or more.

[0072] In addition to this, the partially laminated layer may exhibit at least some characteristics that indicate that the layer was made by transfer of a localized region of a prefabricated layer rather than being deposited onto the microspheres in the form of a vapor phase or a flowable precursor. Thus, a partially laminated reflective layer will be distinguished, for example, from a reflective layer obtained by vapor coating a metallic reflective layer or a dielectric stack reflective layer directly onto the microspheres, from a reflective layer obtained by printing a reflective layer precursor (e.g., silver ink) onto the microspheres, and the like.

[0073] Such distinguishing characteristics may include, for example, the appearance of a minute edge of the layer indicating that the layer is partially separated (e.g., detached) from a layer of material that previously laterally surrounds the detached area. Other distinguishing characteristics may also be found due to the unique nature of the layer being partially laminated to the microspheres. In order to perform the partial lamination of the layer, the layer must at least approximately conform to the shape of the protruding area of ​​the microspheres. Since the layer includes at most a single axis of curvature and the protruding portion of the microsphere includes multiple axes of curvature, the layer cannot conform to the surface of the multi-axis microspheres without exhibiting at least some wrinkles, wrinkles, folds, fractures, etc. (This may be particularly true given the small radius of curvature of the transparent microspheres typically used in retroreflective articles.) Therefore, such features may provide evidence that the layer is a partially laminated layer.

[0074] In many embodiments, it has been found that the local laminated layer exhibits characteristic discontinuities in the form of cracks or gaps, which appear to be fractures caused by bending and / or stretching that occurs during the process of conforming the layer to the protruding portion of the microsphere. Therefore, features such as fracture lines, cracks or gaps present in the layer on the transparent microsphere can provide evidence that the layer is a local laminated layer. It should also be understood that in some cases, the local laminated layer can be identified by the presence of a brittle layer and / or a selective bonding layer as described in detail elsewhere herein. Based on the above discussion, it should be understood that the local laminated layer can be identified by any of several properties and distinguished from other layers, and this characteristic can be used as an indication that the layer is a local laminated layer. Methods for identifying and characterizing local laminated layers are further discussed in detail in U.S. Provisional Patent Application 62 / 739506 and PCT International Patent Application No. US2018 / 057553, both of which are incorporated herein by reference in their entirety.

[0075] It should be emphasized that locally laminated reflective layers that include discontinuities such as wrinkles, cracks, and / or gaps and exhibit considerable variation and non-uniformity, nevertheless work well to provide acceptable retroreflectivity. It should be appreciated that this is a surprising result, considering that past approaches to achieving retroreflectivity have typically involved providing a reflective layer that is extremely consistent, uniform, and uninterrupted within the confines of a single microsphere, and that conforms to the curvature of the microsphere (or a bonding layer thereon) with strict fidelity.

[0076] The following discussion is primarily described in terms of a single layer (eg, a single reflective layer), but should be understood to apply to partially laminated first and second layers. Although the following discussion may refer to reflective layers, they will also be understood to apply to non-reflective partially laminated functional layers.

[0077] like Figure 1 As shown in the exemplary embodiment of , at least some of the partially laminated functional layers (e.g., reflective layers) 30 and / or 530 of the retroreflective elements 20 of the retroreflective article 1 can be embedded layers. In various embodiments, at least approximately, substantially, or essentially all of the functional layers of the retroreflective elements 20 will be embedded layers.

[0078] The embedding layer is a layer disposed adjacent to a portion of the embedding region 25 of the transparent microsphere 21, such as Figure 1 30 and 530 of the exemplary embodiment shown. The embedded layer will at least roughly conform to a portion (typically including the last portion) of the embedded region 25 of the transparent microspheres 21. By definition, the embedded layer will be completely surrounded (e.g., sandwiched) by the combination of at least the binder layer 10 and the transparent microspheres 21 (noting that in some embodiments, some other layer or layers, such as intervening layers such as adhesive layers and / or color layers may also be present in the article 1, as discussed later herein, and may help surround the layer). In other words, the tiny edges of the embedded layer (e.g., edge 31 of layer 30 and edge 531 of layer 530, as shown in FIG. 1 ) will be at least roughly conformable to a portion (typically including the last portion) of the embedded region 25 of the transparent microspheres 21. By definition, the embedded layer will be completely surrounded (e.g., sandwiched) by the combination of at least the binder layer 10 and the transparent microspheres 21 (noting that in some embodiments, some other layer or layers, such as intervening layers such as adhesive layers and / or color layers may also be present in the article 1, as discussed later herein, and may help surround the layer). Figure 1 In the exemplary embodiment shown in FIG. 5 , the transparent microspheres 21 will be "buried" between the transparent microspheres 21 and the binder layer 10 (and possibly other layers), rather than being exposed. That is, the location 26 marking the boundary between the exposed area 24 of the microspheres and the embedded area 25 of the microspheres (which location may be referred to as the "waist" of the microspheres) will be abutted by the edge 16 of the binder layer 10 (or the edge of a layer disposed thereon), rather than by the tiny edge of the embedding layer 30 or 530.

[0079] For transparent microspheres 21 including an embedded layer, no portion of the embedded layer will be exposed so as to extend over (i.e., cover) any portion of the exposed area 24 of the microspheres 21. It should be understood that in the actual industrial production of retroreflective articles of the general type disclosed herein, there may inevitably be small-scale statistical fluctuations, which may result in the formation of a very small number of, for example, tiny portions of a layer, such as a reflective layer, that exhibit tiny edges or areas that are exposed rather than buried. In any actual life production process, such occasional occurrences would be expected; however, the embedded layers as disclosed herein are distinguished from such a situation in which the layer is purposefully arranged in such a way that it will show a large number of exposed tiny edges or areas.

[0080] In some embodiments, the embedding layer (eg, 30 or 530) will be as follows Figure 1 By definition, a topical layer is an embedded layer that does not include any portion that extends away from the embedded region 25 of the microspheres 21 along any lateral dimension of the article 1 to a sufficient extent to bridge the lateral gaps between adjacent transparent microspheres 21. In some embodiments, at least substantially, generally, or essentially all (according to the definition provided previously) of the embedded functional layer (30 and 530) of the retroreflective article will be a topical layer.

[0081] However, in some embodiments, the localized laminate layer may be a "bridging" layer that can bridge multiple (at least two) transparent microspheres. A layer of bridged microspheres is a layer having a first portion that is generally arranged behind at least a portion of a first microsphere and a second portion that is generally arranged behind at least a portion of a second microsphere. Thus, a single such functional layer can operate (e.g., provide reflection) in conjunction with two (or more) transparent microspheres and will be referred to as a "bridging" layer. Some bridged microspheres may include other portions that are generally arranged behind other microspheres. In various embodiments, the bridging layer may bridge two, three, four, or up to ten microspheres.

[0082] The bridging layer is not a local layer as defined herein, however, the peripheral edge of the bridging layer is buried between the transparent microspheres and the binder material; therefore, the bridging layer is an "embedded" layer. It should be understood that the presence of bridging layers may occur statistically, and in some embodiments, a majority of the local laminate layers may be local layers, with each such layer acting as a single transparent microsphere.

[0083] Figure 4 21 and an enlarged separation perspective view of an exemplary partially laminated first layer 30 and an exemplary partially laminated second layer 530. Figure 4 In order to facilitate visualization of layers 30 and 530, the adhesive layer 10 (described later herein) is omitted. Figure 5 1 is an enlarged isolated side schematic cross-sectional view of transparent microspheres and an exemplary partially laminated first layer 30 and an exemplary partially laminated second layer 530. (In Figure 4 and Figure 5, both layers 30 and 530 are embedded and localized. ) As shown in these figures, the first layer 30 will include a major forward surface 32 that generally exhibits a generally arcuate shape, for example wherein at least a portion of the forward surface 32 at least generally conforms to a portion of the major rearward surface 23 of the microsphere 21. In some embodiments, the major forward surface 32 of layer 30 may be in direct contact with the major rearward surface 23 of the microsphere 21; however, in some embodiments, the major forward surface 32 of layer 30 may contact a layer that is itself disposed on the major rearward surface 23 of the microsphere 21, as discussed in more detail elsewhere herein. A layer disposed in this manner may be, for example, a transparent layer that serves, for example, as a protective layer, as a bonding layer, as an adhesive layer, or as an adhesion promoting layer; alternatively, such a layer may be an optical retardation layer or a color layer. In some embodiments, such a layer may serve multiple functions (for example, it may serve as a color layer and an adhesive layer). The major rearward surface 33 of layer 30 (for example, as Figure 1 The surface shown in contact with the front surface 12 of the binder layer 10, or the surface of a layer present thereon) can, but does not necessarily have to, be at least approximately coincident with (e.g., locally parallel to) the major front surface 32 of the reflective layer 30. This may depend, for example, on the specific manner in which the reflective layer is disposed on the transparent microspheres, as discussed later herein.

[0084] Similarly, the second layer 530 will include a major forward-facing surface 532 that generally exhibits a generally arcuate shape, e.g., wherein at least a portion of the forward-facing surface 532 at least generally conforms to a portion of the major rearward-facing surface 23 of the microsphere 21. In some embodiments, the major forward-facing surface 532 of the layer 530 may be in direct contact with the major rearward-facing surface 23 of the microsphere 21; however, in some embodiments, the major forward-facing surface 532 of the layer 30 may be in contact with a layer that is itself disposed on the major rearward-facing surface 23 of the microsphere 21, as discussed above. The major rearward-facing surface 533 of the layer 530 (e.g., as Figure 1 The surface shown in contact with the front surface 12 of the adhesive layer 10, or the surface of the layer present thereon) can, but need not necessarily be, at least generally coincident with (e.g., partially parallel to) the major front surface 532 of the layer 530. (These discussions apply to a portion of the second layer 530 arranged in parallel with the first layer 30; if the layer 530 includes a portion in series with the layer 30, the portion may include the front surface 532 in contact with the rear surface 33 of the first layer 30, as described above).

[0085] It should be understood that in some embodiments, a layer may be partially laminated to the microspheres by transferring to the protruding portions of the microspheres, while the microspheres are partially (and temporarily) embedded in the carrier. Because the diameters of different microspheres may be slightly different, and / or the depths at which different microspheres are embedded in the carrier may vary, different microspheres may protrude outward from the carrier at different distances. In some cases, microspheres protruding outward from the carrier may receive a larger amount of material locally transferred thereto than microspheres more deeply embedded in the carrier. In this case, it should be understood that the locally laminated layers of various microspheres may differ from each other in the angular arc occupied by the layer. Unless otherwise specified, this parameter and all similar parameters will be understood to be obtained in the form of average values ​​taken over multiple retroreflective elements, microspheres, and locally laminated layers.

[0086] The local laminate layer may exhibit any suitable thickness (e.g., an average thickness measured at several locations within the layer). It should be understood that different methods of making such a layer may produce layers of different thicknesses. In various embodiments, the local laminate layer may exhibit an average thickness of at least 0.01 micron, 0.05 micron, 0.1 micron, 0.2 micron, 0.5 micron, 1 micron, 2 microns, 4 microns, or 8 microns to a maximum of 100 microns, 80 microns, 60 microns, 40 microns, 20 microns, 10 microns, 7 microns, 5 microns, 4 microns, 3 microns, 2 microns, or 1 micron (e.g., measured at several locations within the layer). In various embodiments, the local laminate layer may include an average thickness of at least 10 nanometers, 20 nanometers, 40 nanometers, or 80 nanometers; in other embodiments, such a layer may include an average thickness of at most 10, 5, 2, or 1 micron, or at most 400, 200, or 100 nanometers. If the layer (or a group of sub-layers of, for example, a dielectric stack) is a layer of a multilayer stack (such as a transfer stack described later herein), these thicknesses apply only to the transferred layer itself.

[0087] Conventional methods of producing retroreflective articles (whether using, for example, vapor-coated transparent microspheres, prismatic elements such as cube corners, etc.) generally attempt to achieve as much uniformity as possible in geometric parameters. It is therefore apparent that the methods disclosed herein are different from conventional methods of making retroreflective articles. The arrangements of the present invention tolerate considerable variation in the shapes, sizes, etc. of the various reflective layers, as long as acceptable overall performance (e.g., a balance between retroreflectivity in retroreflected light and color fidelity / vividity in ambient light) is achieved.

[0088] Additionally, in some embodiments, the plurality of transparent microspheres may completely lack a partially laminated layer, such as a partially laminated reflective layer. That is, in some embodiments, the partial lamination process may leave a plurality of microspheres without a reflective layer disposed thereon. It has been found that in many cases, the presence of some transparent microspheres lacking a reflective layer disposed thereon is acceptable (e.g., a sufficiently high coefficient of retroreflection may still be obtained). In various embodiments, at least 30%, 50%, 70%, or 90% of the retroreflective elements of the retroreflective article each include a first partially laminated embedded reflective layer and / or a second partially laminated embedded reflective layer.

[0089] As described above, in some embodiments, the partially laminated reflective layer (e.g., 30 or 530) may include a metal reflective layer, such as a single layer or multiple layers of a vapor deposited metal (e.g., aluminum or silver). In some embodiments, the partially laminated reflective layer may include a dielectric reflective layer, which is composed of an optical stack of a high refractive index layer and a low refractive index layer combined to provide reflective properties. Dielectric reflective layers are further described in detail in U.S. Patent Application Publication No. 2017 / 0131444, which is incorporated herein by reference in its entirety for this purpose. In a particular embodiment, the dielectric reflective layer may be a so-called layer-by-layer (LBL) structure, in which each layer of the optical stack (i.e., each high refractive index layer and each low refractive index layer) itself consists of a sub-stack of multiple bilayers. Each bilayer is in turn composed of a first sublayer (e.g., a positively charged sublayer) and a second sublayer (e.g., a negatively charged sublayer). At least one sublayer of the bilayer of the high refractive index substack will include a component that imparts a high refractive index, while at least one sublayer of the bilayer of the low refractive index substack will include a component that imparts a low refractive index. LBL structures, methods for making such structures, and retroreflective articles including dielectric reflective layers having such structures are described in detail in U.S. Patent Application Publication No. 2017 / 0276844, which is incorporated herein by reference in its entirety. In some embodiments, the retroreflective layer may therefore include multiple sublayers. In some embodiments, a hybrid configuration may be used, in which both a metallic reflective layer and a dielectric reflective layer may be present, such as discussed in U.S. Patent Application Publication No. 2017 / 0192142. In some embodiments, a layer of a transfer stack (e.g., a selective bonding layer 303 or an embrittled layer 302 as described elsewhere herein) may be used as a layer of a dielectric stack.

[0090] like Figure 1As shown in the exemplary embodiment in , in some embodiments, an intermediate layer 50 (e.g., a transparent layer of an organic polymer material) can be provided so that a portion or all of the intermediate layer is located behind the microspheres 21 and in front of at least a portion of the partial laminate layer 30 and / or 530. Thus, at least a portion of such an intermediate layer 50 can be sandwiched between the microspheres 21 and the layers 30 and / or 530, for example, the forward surface 52 of the intermediate layer 50 is in contact with the rearward surface of the embedded region 25 of the microspheres 21, and the rearward surface 53 of the intermediate layer 50 is in contact with the forward surface 32 of the layer 30 or the forward surface 532 of the layer 530. In some embodiments, such a layer 50 can be continuous so as to have a portion residing on the front surface 4 of the article 1 in addition to being present behind the microspheres 21, such as Figure 1 In other embodiments, such a layer may be discontinuous (e.g., the layer may be a partially embedded layer) and may only be present behind the microspheres 21. Furthermore, even a "continuous" layer 50 may exhibit occasional through-holes or cavities at locations where the layer precursor did not fully wet into the gaps between the microspheres 21, as previously described.

[0091] This intermediate layer can play any desired function. In some embodiments, the intermediate layer can be used as a physical protective layer and / or a chemical protective layer (e.g., providing enhanced wear resistance, corrosion resistance, etc.). In some embodiments, this layer can be used as an adhesive layer (e.g., a bonding layer or an adhesion promoting layer), which can be bonded by a functional layer (e.g., a reflective layer). In some embodiments, this layer can be used as a passivation layer or an optical retardation layer. It should be understood that some intermediate layers can be used for more than one of these purposes, such as all. In some embodiments, this intermediate layer can be transparent (specifically, it can be at least substantially free of any colorant, etc.). Organic polymer layers (e.g., protective layers) and their potential suitable compositions are described in detail in U.S. Patent Application Publication No. 2017 / 0276844, which is incorporated herein by reference in its entirety. In a specific embodiment, this layer can be composed of a polyurethane material. Various polyurethane materials suitable for such purposes are described in U.S. Patent Application Publication No. 2017 / 0131444, which is incorporated herein by reference in its entirety.

[0092] In some embodiments, at least some of the retroreflective elements include at least one color layer. In various embodiments, the color layer may be one of the first layer and the second layer as previously defined and described herein; alternatively, the color layer may be a separate additional layer. The term "color layer" is used herein to refer to a layer that preferentially allows electromagnetic radiation to pass through at least one wavelength range between 380nm and 1mm while preferentially minimizing the passage of electromagnetic radiation within the wavelength range by absorbing at least some of the radiation in at least one other wavelength range between 380nm and 1mm. The color layer as defined herein performs wavelength selective absorption of electromagnetic radiation by using a colorant (e.g., a dye or pigment) disposed in the color layer. Therefore, as will be known to those of ordinary skill based on the discussion herein, the color layer is distinguished from the reflective layer (and from the transparent layer). Various types of color layers are described in U.S. Provisional Patent Application 62 / 675020 and PCT International Patent Application No. US2018 / 057555. Any such color layer may be arranged so that light reflected by the retroreflective element passes through the color layer so that the retroreflected light exhibits the color imparted by the color layer. In some embodiments, the colored layer can serve some other function in addition to imparting color to the retroreflected light (eg, an adhesive layer, an adhesion promoting layer, or a bonding layer).

[0093] In some embodiments, the color layer can be a discontinuous color layer, such as a partial color layer. In a particular embodiment, the partial color layer can be an embedded color layer (wherein the terms partial and embedded have the same meanings as described above). The presence of a color layer (e.g., a partial embedded color layer) in at least some of the retroreflected light path of a retroreflective article can allow the article to include at least some areas that exhibit colored retroreflected light, regardless of the color or colors that these areas (or any other areas of the article) exhibit in ambient (non-retroreflected) light.

[0094] Retroreflective article 1 can be arranged to provide desired control over the appearance of article 1 in ambient (non-retroreflective) light. Figure 6 In an exemplary arrangement of FIG. 1 , portions of the front surface 4 of the article 1 (e.g., in areas of the front side 2 of the article 1 not occupied by the transparent microspheres 21) will be provided by a visually exposed front surface 14 of the binder layer 10 (after removal of the carrier 110). In such embodiments, the appearance of the front side 2 of the article 1 in ambient light may therefore be affected by the color (or lack of color) of the binder layer 10 laterally interposed in the areas 13 of the binder layer 10 between the microspheres 21. If the continuous layer 50 is a transparent layer, then the front surface 14 may be exposed to light. Figure 1Similar effects are achieved in arrangements of the type shown. Therefore, in some embodiments, the binder layer 10 can be a binder layer loaded with a colorant (e.g., loaded with a pigment). The pigment can be selected to impart any suitable color in ambient light, such as fluorescent yellow, green, orange, white, black, etc. As described above, in certain embodiments, the arrangement herein can allow the true color of the binder layer and the retroreflective article to be more fully realized.

[0095] In some embodiments, the appearance of the retroreflective article 1 in ambient light can be manipulated, for example, by the presence and arrangement of one or more colored layers on the front side of the article 1. In some embodiments, any such colored layer, for example in combination with a colorant-loaded binder, can be configured so that when viewed in ambient light, the front side of the article 1 exhibits a desired image (a term broadly encompassing, for example, informational markings, signage, aesthetic designs, etc.). In some embodiments, the article 1 can be configured (whether by manipulating the reflective layer and / or manipulating any colored layer in the retroreflective light path) to exhibit an image when viewed in retroreflected light. In other words, any arrangement that can affect the appearance of the article 1 in ambient light (e.g., by using a colorant-loaded binder, using a colorant-loaded layer on the front side 4 of the article 1, etc.) is used in combination with any arrangement that can manipulate the appearance of the article 1 in retroreflected light (e.g., by using a colored layer, such as using a colored layer in the retroreflective light path, such as locally embedded colored layers).

[0096] As discussed above, in some cases, the appearance of article 1 in ambient light may be less important or may not be a significant consideration, such as in cases where the wavelength dependence of the article's retroreflectivity, and particularly how such dependence varies with angle of incidence, is of most importance.

[0097] exist Figure 6 In some embodiments of the general type shown, a retroreflective article 1 as disclosed herein can be provided as part of a transfer article 100 that includes the retroreflective article 1 and a removable (disposable) carrier layer 110 that includes a front major surface 111 and a rear major surface 112. In some convenient embodiments, the retroreflective article 1 can be constructed on such a carrier layer 110 that can be removed for ultimate use of the article 1 as described later herein. For example, the front side 2 of the article 1 can be releasably contacted with the rear surface 112 of the carrier layer 110, as described in the example of FIG. Figure 6 As shown in the exemplary embodiment of FIG.

[0098] Retroreflective article 1 (eg, while still part of transfer article 100) may be coupled to any desired substrate 130, such as Figure 6As shown. This can be accomplished in any suitable manner. In some embodiments, this can be accomplished by using an adhesive layer 120 that couples the article 1 to a substrate 130, wherein the rear side 3 of the article 1 faces the substrate 130. Such an adhesive layer 120 can bond the adhesive layer 10 of the article 1 (or any layer disposed thereon rearwardly) to the substrate 130, for example, wherein one major surface 124 of the adhesive layer 120 is bonded to the rear surface 15 of the adhesive layer 10, and wherein the other relative major surface 125 of the adhesive layer 120 is bonded to the substrate 130. Such an adhesive layer 120 can be, for example, a pressure-sensitive adhesive (of any suitable type and composition) or a heat-activated adhesive (e.g., a "hot press" adhesive layer).

[0099] The term "substrate" is used broadly and encompasses any article, portion of an article, or collection of articles to which it is desired, for example, to couple or mount a retroreflective article 1. Furthermore, the concept of a retroreflective article coupled to or mounted on a substrate is not limited to configurations in which the retroreflective article is, for example, attached to a major surface of a substrate. Rather, in some embodiments, the retroreflective article may be, for example, a strip, filament, or any suitable high aspect ratio article, such as threaded, woven, sewn, or otherwise inserted and / or passed through a substrate such that at least some portion of the retroreflective article is visible. Indeed, such retroreflective articles (e.g., in the form of yarns) may be assembled (e.g., woven) with other, for example, non-retroreflective articles (e.g., non-retroreflective yarns) to form a substrate in which at least some portion of the retroreflective article is visible. The concept of a retroreflective article coupled to a substrate thus encompasses situations in which the article effectively becomes part of the substrate.

[0100] In some embodiments, substrate 130 may be a part of clothing. The term "clothing" is widely used, and generally encompasses any article or part thereof intended to be worn, carried, or otherwise present on or near the user's body. In such embodiments, article 1 may be directly connected to clothing, for example, by adhesive layer 120 (or by stitching or any other suitable method). In other embodiments, substrate 130 itself may be a support layer, to which article 1 is connected, for example, by bonding or stitching, and which increases the mechanical integrity and stability of the article. The entire assembly including the support layer may then be connected to any suitable article (e.g., clothing) as required. Typically, carrier 110 is maintained in position during article 1 being connected to a desired entity, and then it may be convenient to remove it after the connection is complete. Strictly speaking, when carrier 110 is maintained in position on the front side of article 1, region 24 of transparent microspheres 21 will not yet be exposed to air, and therefore retroreflective element 20 may not yet exhibit a desired retroreflectivity level. However, an article 1 that is removably disposed on a carrier 110 that is to be removed for actual use of the article 1 as a retroreflector would still be considered a retroreflective article as characterized herein.

[0101] In some convenient embodiments, retroreflective article 1 can be manufactured by starting with a disposable carrier layer 110. Transparent microspheres 21 can be partially (and releasably) embedded in carrier layer 110 to form a substantially single layer of microspheres. For such purposes, in some embodiments, carrier layer 110 can conveniently include, for example, a heat-softenable polymer material that can be heated and the microspheres deposited thereon in a manner such that they are partially embedded therein. The carrier layer can then be cooled so as to releasably retain the microspheres in that condition for further processing.

[0102] Typically, the deposited microspheres are at least slightly laterally spaced from each other, although occasional microspheres may be in lateral contact with each other. The pattern (i.e., packing density or proportional area coverage) of the microspheres deposited on the support will determine the pattern of these microspheres in the final article. In some embodiments, the microspheres can be provided in a predetermined pattern, for example, by using the methods described in U.S. Patent Application Publication No. 2017 / 0293056, which is incorporated herein by reference in its entirety.

[0103] In various embodiments, the microspheres 21 may be partially embedded in the carrier 110, for example, up to about 20% to 50% of the diameter of the microspheres. Regions 25 of the microspheres 21 that are not embedded in the carrier protrude outward from the carrier so that these microspheres can subsequently receive the partially laminated layers 30 and 530 and the binder layer 10 (and any other layers as desired). These regions 25 (which will form the embedded regions 25 of the microspheres in the final article) will be referred to herein as the protruding regions of the microspheres during the time when the microspheres are set on the carrier layer in the absence of the binder layer. In conventional manufacturing processes, there may be some variation in the depth to which different microspheres are embedded in the carrier 110, which may affect the size and / or shape of the layers that are partially laminated to the portions of the protruding surfaces of the different microspheres.

[0104] The support layer including transparent microspheres is described as a temporary beaded support in the working embodiments herein. Such a microsphere-bearing support having an organic polymer intervening layer (e.g., an adhesive layer) deposited thereon is referred to as a polymer-coated bead support in the working examples. Further details of suitable support layers, methods of temporarily embedding transparent microspheres in support layers, and methods of using such layers to produce retroreflective articles are disclosed in U.S. Patent Application Publication No. 2017 / 0276844.

[0105] After the microspheres 21 are partially embedded in the carrier 110 (and coated with an organic polymer layer, for example), the first functional layer 30 and the second functional layer 530, such as a reflective layer (which will become an embedded layer after the binder layer 10 is formed) can be formed on portions of the protruding regions 25 of at least some of the microspheres. This will form an intermediate product 1000, such as Fig. 9 This is shown in the exemplary embodiment of FIG. , which will be discussed in more detail below.

[0106] In many embodiments, local lamination may be performed so that the layer is only locally transferred to a portion of the protruding region 25 of the microsphere 21, and not to, for example, the surface 112 of the carrier 110. Any such process may be controlled so that the layer is not transferred to the entire protruding region 25 of the microsphere 21. That is, in some embodiments, the process may be implemented so that the layer is transferred only to the outermost portion of the protruding region 25 of the microsphere 21 (which outermost portion will become the last portion of the embedded region 25 of the microsphere 21 in the final article). Such a first lamination process may, for example, provide a first layer as a "polarizing cover" layer of the general type previously described herein. In some embodiments, a second subsequent lamination process may, for example, provide a second layer as a spherical segment layer that occupies a larger angular arc of the microsphere than the first layer. Methods for achieving such an arrangement are discussed in detail below.

[0107] The following discussion is described with a single layer (eg, a single reflective layer), but should be understood to apply to partially laminated first and second layers. Although the following discussion may refer to reflective layers, they will also be understood to apply to non-reflective partially laminated functional layers.

[0108] In order to perform the local lamination of the functional layer onto the protruding portions of the transparent microspheres as described herein, an arrangement must be made that enables the preformed layer to contact the portion of the carrier bearing the transparent microspheres and the preformed layer laminated thereto. Such an arrangement can be facilitated by providing the functional layer as part of a multilayer transfer stack that includes a peeling interface that allows the functional layer to be separated from the other layers of the stack. In some embodiments of this general type, the functional layer (e.g., reflective layer) 30 can be provided as part of a multilayer transfer stack 350, such as Figure 7 301 as a reflective layer 30, which itself includes a reflective layer 301 sandwiched between a front embrittlement layer 302 and a rear selective bonding layer 303. The transfer stack 350 also includes a peelable support assembly 360, which includes a support substrate 361 and a peeling layer 362. These layers are arranged so that the rear surface of the selective bonding layer 303 contacts the front surface of the peeling layer 362 to form a peeling interface 331. The front surface of the selective bonding layer 303 contacts the reflective layer 301 and is non-peelably bonded to the reflective layer. Therefore, the layer 303 establishes a selective peeling interface 331 and a selective bonding interface 332, thereby designating the layer 303 as a selective bonding layer.

[0109] The multilayer transfer stack 350 may contact the protruding portions of the carrier-supported microspheres 21, such as Figure 7303. The frontmost surface of the transfer stack (in this case, the front-facing surface of the embrittled layer 302) contacts the surface 53 of the adhesive layer 50 disposed on at least the raised portion of the microsphere 21. Bonding is established between the layer 302 and the adhesive layer 50. The transfer stack 350 has been configured so that the interface 331 is a selectively peelable (weakly bonded) interface, and the reflective layer 30 (including the embrittled layer 302, the reflective layer 301, and the selective adhesive layer 303) will remain bonded to the protruding portion of the microsphere, while the peelable support assembly 360 is peeled from the reflective layer 30 (at the selectively peelable interface 331) and removed.

[0110] Figure 7 is an idealized cross-sectional view that does not capture the fact that lamination occurs along the surface of the microsphere along multiple axes of curvature. Figure 7 As shown, the reflective layer 30 is peeled off from the peelable support assembly 360, and the local area of ​​the prefabricated reflective layer 30 laminated to the microsphere 21 will be separated from the area of ​​the prefabricated reflective layer that previously laterally surrounds the local area. (The area of ​​the prefabricated reflective layer 30 that is not transferred to the microsphere will generally remain with the peelable support assembly 360 and be removed with the peelable support assembly.)

[0111] The composition of each of the above layers can be selected as desired. The support substrate 361 of the peelable support assembly 360 can be, for example, any suitable organic polymer film, such as polyester, biaxially oriented polypropylene, etc. Other potentially useful materials for the support substrate 361 are described in the '992 application cited above.

[0112] The peeling layer 362 may be any suitable material disposed, for example, deposited on or on any layer of the main surface of the support substrate 361. In some embodiments, the peeling layer 362 may include a metal layer. The metal layer may include at least one selected from the following: a single metal, two or more metals as a mixture, an intermetallic compound or alloy, a semimetal or a metalloid, a metal oxide, a metal and mixed metal oxide, a metal and mixed metal fluoride, a metal and mixed metal nitride, a metal and mixed metal carbide, a metal and mixed metal carbonitride, a metal and mixed metal oxynitride, a metal and mixed metal boride, a metal and mixed metal boron oxide, a metal and mixed metal silicide, diamond-like carbon, diamond-like glass, graphene, and combinations thereof. In some embodiments, the metal layer may be conveniently formed of Al, Zr, Cu, Ni, Cr, Ti, or Nb. In some embodiments, the peeling layer 362 may include a doped semiconductor layer. In some embodiments, the doped semiconductor layer may be conveniently formed of Si, Si doped with B, Si doped with Al, and / or Si doped with P. In various embodiments, the release layer 362 can be prepared by evaporation, reactive evaporation, sputtering, reactive sputtering, chemical vapor deposition, plasma enhanced chemical vapor deposition, and atomic layer deposition. Preferred methods include vacuum preparation, such as sputtering and evaporation.

[0113] The selective adhesive layer 303 may include any material that demonstrates required strippability combination and bonding on another relative main surface on a major surface. In many embodiments, this material may be selected from a variety of (methyl) acrylate and / or (methyl) acrylamide materials, as discussed in detail in the '992 provisional application cited above. If the selective adhesive layer will be formed by the rapid evaporation of monomer, vapor deposition may be used, then crosslinked, volatile (methyl) acrylate and / or (methyl) acrylamide monomer or oligomer. Suitable material will show enough vapor pressures to evaporate in an evaporator and condense into liquid or solid coatings in a vapor coater. The example of potential suitable material is listed in '992 provisional application. Tricyclodecane dimethanol diacrylate is a specific example of suitable material, and can be conveniently applied by, for example, condensing organic coatings, subsequently by the free radical polymerization initiated by UV, electron beam or plasma.

[0114] Reflective layer 301 can be any suitable reflective layer (e.g., a metal layer such as silver or aluminum, or a metal alloy) or collection of sublayers (e.g., it can be a dielectric stack). As described above, in some embodiments, layer 30 can be a functional layer that is non-reflective and does not include reflective layer 301. For example, functional layer 30 can include a release layer that provides a rearward-facing passivated release surface after layer 30 is laminated to the microspheres, to which the second layer may not be bonded.

[0115] The embrittlement layer 302 may be any layer that exhibits suitable brittle properties that can enhance the ability of the transferred region of the prefabricated reflective layer to break away from the regions of the prefabricated reflective layer that previously laterally surround the transferred region. (It should be emphasized, however, that such an embrittlement layer is optional and that many working example samples have been successfully produced without the presence of an embrittlement layer.) Many silicon oxides (e.g., silicon aluminum oxide (SiAlO x ) obtained, for example, by sputtering coating from a target comprising silicon and aluminum in an oxygen-containing atmosphere) may be very suitable for such applications (again, note that this embrittlement layer is optional and may be included or omitted in each case).

[0116] The thickness of each layer can be selected as required. In various embodiments, the thickness of the embrittlement layer can change in the range of, for example, 1, 2, 4 or 6nm to 100, 80, 60, 40, 30 or 20nm. In various embodiments, the reflective layer can change in the range of, for example, 10, 20, 40 or 80nm to 40, 20, 10, 7, 5, 4, 3, 2 or 1 micron. In various embodiments, the selective bonding layer can change in the range of, for example, 20, 40 or 60nm to 500, 400, 300, 200 or 100nm. In various embodiments, the peeling layer can change in the range of, for example, 2, 4 or 6nm to 40, 30 or 20nm. In various embodiments, the supporting substrate can change in the range of, for example, 0.5, 1.0, 2 or 4 mils to 20, 10, 6, 3, 1.5 or 0.6 mils.

[0117] In many convenient embodiments, the multilayer transfer stack 350 can be constructed starting with a support substrate 361 (e.g., biaxially oriented polypropylene (BOPP) provided with a release layer 362, e.g., a metal layer such as an aluminum coating), thereby providing a releasable support assembly 360. The remaining layers can then be sequentially deposited, starting with the selective adhesive layer 303, on the release layer bearing side of the support substrate.

[0118] therefore, Figure 7 The general type of process shown will produce Figure 2 302 will be in the path of the retroreflected light and will therefore be selected to ensure that it does not unacceptably affect the retroreflective performance. In some such embodiments, the embrittlement layer is transparent to the retroreflected light. Typically, such an embrittlement layer will be relatively thin (e.g., 50, 30, 20, or 10 nm or less). Although Figure 7 The exemplary description shows the peelable support assembly 360 being removed in line with the lamination of the reflective layer 30 to the microspheres, but in practice such removal may be performed later; for example, a set of carrier-bearing microspheres having a transfer stack 350 disposed thereon may be stored, for example, as a roll article, with the peelable support assembly 360 later peeled off and removed.

[0119] It should be understood that if such a method is used to form the first partial laminate layer 30, the resulting layer 30 formed thereby has its rearmost surface 33 provided by the high release major surface of the selective bonding layer 303 (which surface is exposed on the above-mentioned multilayer transfer stack and is separated at the interface 331 between the selective bonding layer 303 and the release layer 362). Such an arrangement can thus provide a first layer 30 whose rearmost surface is a high release layer, which can facilitate the previously described situation in which the second partial laminate layer is not bonded to (e.g., not held in place behind) the first partial laminate layer. In other words, this method can be used to perform annular transfer lamination of the second partial laminate layer.

[0120] As previously mentioned, in some embodiments, the functional (eg, reflective) layer 30 may include Figure 3 The general type of arrangement shown, wherein the embrittlement layer 302 and the selective bonding layer 303 are positioned with respect to Figure 2 The positions shown are interchanged. Figure 8 The transfer stack 380 of the conformable support shown in the exemplary embodiment of the present invention uses a modified version of the above-mentioned lamination process to obtain such an arrangement. In such a method, a preliminary assembly ( Figure 8 302). A selective bonding layer 303, a reflective layer 301, and an embrittlement layer 302 may be sequentially deposited on the release layer of the assembly to produce a preliminary assembly. Such a preliminary assembly may then be laminated to a suitable conformable substrate 381 (described in detail below) with the major surface of the embrittlement layer 302 in contact with the major surface of the conformable substrate 381. The conformable substrate may be configured so that the two surfaces (in Figure 8 The adhesive force between the selective adhesive layer 303 and the peeling layer of the peelable support component is greater than the adhesive force between the selective adhesive layer 303 and the peeling layer of the peelable support component. The peelable support component can therefore be separated from the other layers to leave a transfer stack 380 of a conformable support, such as Figure 8 As shown. Figure 8 3, the peelable support assembly has been removed and is therefore not shown; however, numeral 331 indicates the location of the interface that previously existed between the selective bonding layer 303 and the release layer of the peelable support assembly. Thus, in a preliminary step that occurs before the actual lamination of the reflective layer to the microspheres, the method uses the selective bonding / release properties of layer 303 to peel the transfer stack from the preliminary assembly.

[0121] It should be noted that for convenience, the term "conformable substrate" is used to refer to the entity used in the local lamination process (e.g., Figure 8The compliant substrate is different from the substrate to which the retroreflective article can be attached (e.g., Figure 6 Item 130).

[0122] Therefore, the above preliminary approach will produce Figure 8 The transfer stack 380 of the general type of conformable support shown. The transfer stack can then be contacted with the protruding portion of the transparent microspheres (that is, in contact with the adhesive layer 50 present thereon) to perform a local lamination process in the general manner described above. After performing the lamination, the conformable substrate 381 can be removed at any suitable time or removed in line with the lamination at a later time. This can be achieved by ensuring that the adhesion at the interface 334 between the surface of the conformable substrate 381 and the embrittlement layer 302 (or the reflective layer 301, if there is no embrittlement layer) is less than the adhesion at all other interfaces. In such an arrangement, the selective adhesive layer 303 will be in the retroreflective light path, and therefore will be selected to ensure that it will not unacceptably affect the retroreflective performance. In some such embodiments, the selective adhesive layer is transparent to the retroreflected light.

[0123] Figure 8 The method (and the resulting product) and Figure 7 There are several differences from the previously described methods. First, as described above, the position of the selective bonding layer 303 (and the optional embrittlement layer 302, if present) relative to the retroreflected light path is different. In addition, the final surface of the layer thus formed can be Figure 8 The rear surface of the medium embrittlement layer 302 (if present) or the rear surface of the reflective layer 301, rather than the high release surface of the selective release layer. Such an arrangement can thus provide a first layer 30 whose last surface is not a high release layer and can thus facilitate the previously described situation in which the second partial laminate layer is indeed bonded to the first partial laminate layer (e.g., held in place behind it). In other words, this method can be used to perform a complete transfer lamination of the second partial laminate layer.

[0124] In addition, the use of conformable substrate 381 can allow functional layer 30 or 530 (including all its component layers) to be more actively locally conformal along the multi-dimensional curved surface of transparent microspheres. In some embodiments, the use of a more actively conformable substrate 381 can produce a local laminated layer that exhibits a larger area coverage percentage of the embedded area of ​​the microspheres (e.g., occupying a larger angular arc). Therefore, the local lamination process of the transfer stack using a conformable support can be advantageously used, for example, to provide a second local transfer layer that exhibits a larger area coverage of the microspheres (e.g., exists as a spherical segment) compared to the first local transfer layer (e.g., exists as a polarizing cover). An arrangement for achieving this general type of behavior is shown in Working Example 2 of the working examples of this article. However, as discussed later, various parameters and process conditions can be manipulated to affect the area coverage percentage of the local laminated layer; therefore, it is not necessarily necessary to use a conformable substrate to obtain a high percentage of area coverage. In other words, the use of a conformable substrate is only one of several parameters that can be varied to promote a specific result.

[0125] Any sheet or film-like material (e.g., an organic polymer sheet or film) that exhibits suitable conformability may be a possible candidate for conformable substrate 381. Any such material is selected so that it can be peeled off from the surface of embrittlement layer 302 (or, for example, the surface of reflective layer 301, if embrittlement layer 302 is not present) so that after the functional layer is laminated to the microspheres, conformable substrate 381 can be separated from the surface. However, the material must also be selected so that its bonding strength to any such layer is greater than the bonding strength of the selective bonding layer 303 to the peeling layer of the peeling assembly (so that the peeling assembly can be removed in the above-mentioned preliminary step). Various organic polymer materials may be suitable for achieving this role. For example, suitable materials may be selected from styrene-isoprene rubber, styrene-butadiene rubber, butyl rubber, etc. Some such materials may be selected from a general type of styrene-rubber block copolymer known as KRATON polymers such as KRATON SIS (purchased from KRATON POLYMERS LLC, Houston, TX, Houston, Texas). In some embodiments, it has been found that a multilayer material comprising a highly elastic core sandwiched between lower elastomeric skins consisting of a polyolefin plastomer is particularly suitable. In some embodiments, the conformable substrate may be highly conformable along all dimensions (e.g., it may not have asymmetric mechanical properties of the type exhibited by some highly oriented polymer films). In some embodiments, the conformable substrate may be configured to be elastically conformable. For example, the substrate may exhibit an elongation at break of at least 200%, 400%, or 600%, and may be a single layer or multilayer construction as previously described herein. In various embodiments, the thickness of such a substrate may be, for example, 10, 20, 50, or 100 microns to 5000, 2000, 1000, 500, 400, or 200 microns.

[0126] The above described partial lamination of the layer to the protruding portion of the transparent microsphere (whether by Figure 7 The general type of "direct" lamination shown is still based on Figure 8 The general manner shown (lamination assisted by a conformable substrate) can be performed in any suitable manner. In many convenient embodiments, the above-described partial lamination can be performed by stacking the carrier-bearing microspheres and the multilayer transfer stack together in a lamination nip between two backing rolls. The conditions for performing this operation can be varied as desired. In particular, the process conditions can be varied to affect the extent to which each layer contacts (e.g., "wraps around") and transfers to the protruding area of ​​the microspheres. This coverage can be characterized, for example, by the angular arc previously described, and indicates the extent to which the functional layer will cover the embedded area of ​​the microspheres in the final retroreflective article.

[0127] It has been noted that the presence or absence of a conformable substrate during the lamination process can affect the "wrap-around" of the microspheres achieved by the laminated layers (as manifested, for example, by the arc of the angle occupied by the laminated layers). It has also been found that the hardness of the first and second backing rollers that support the carrier-bearing microspheres and the transfer stack, respectively, during lamination can be effectively adjusted. In some embodiments, one or both backing rollers can be hard-surfaced (e.g., one or both can include a metal surface such as steel), for example, having a Rockwell hardness (HRC) of at least 40. In some embodiments, one or both backing rollers can be soft-surfaced, for example, having an elastomeric or rubberized coating (e.g., having a Shore A hardness of less than 100, 80, 70, 60, or 50). In the case where one of the backing rollers is hard-surfaced (e.g., steel) and the other is soft-surfaced (e.g., rubber), the best performance is generally achieved with a soft-surfaced roller that supports the transfer stack and a hard-surfaced roller that supports the carrier-bearing microspheres.

[0128] The pressure with which the backing rolls are directed toward each other during the lamination process can also be manipulated (e.g., from a low of about 50 pounds per linear inch, to a moderate value of about 400 pounds per linear inch, to a high value of about 1700 pounds per linear inch), with higher pressures generally resulting in greater area coverage of the microspheres by the layer thus transferred, as expected. In general, it has been found that the presence of a compliant substrate in a multilayer transfer stack significantly reduces the lamination pressure required to achieve a given area coverage. Similarly, the use of a soft-surfaced backing roll can allow for a reduction in lamination pressure (although not necessarily to the same extent as the use of a suitable compliant substrate in a multilayer transfer stack) and / or can provide a more macroscopically uniform appearance of the resulting article.

[0129] Thus, general guidelines regarding the effects of various processing parameters can be provided. Thus, for example, in some embodiments, a local lamination process, such as a first local lamination process, can be performed using a hard surface (e.g., steel) backing roller operating at a lamination pressure of about 800 pounds per linear inch (PLI). In some cases, this can provide a relatively small first local lamination layer, such as a polarizing cover layer, for the microspheres. The article output by this process can then be subjected to a similar process (again using two steel backing rollers), but operated at a higher pressure of, for example, about 1500 PLI. This second, more vigorous lamination can provide a second local lamination layer of relatively larger area for the microspheres, such as including a spherical segment that at least partially surrounds the first local lamination layer. More details of such methods are provided in Working Example 1.

[0130] In some embodiments, the local lamination process (e.g., the first lamination process) can be performed with a soft-surfaced backing roller (e.g., a silicone rubber surfaced roller having a Shore A hardness of about 68). Thus, for example, a soft-surfaced backing roller can be used at a lamination pressure of about 400 PLI-600 PLI. Further details of such a method are illustrated, for example, in Working Example 2, where a first local lamination is performed with a nip including a steel backing roller and a steel backing roller having a silicone rubber sleeve having a Shore A hardness of 68, operating at about 500 PLI, followed by a second, more aggressive local lamination using two steel backing rollers operating at about 1000 PLI.

[0131] In some embodiments, a local lamination process (e.g., a second local lamination process) can be performed using a transfer stack that relies on a conformable support of a conformable substrate. Further details of such methods are illustrated, for example, in Working Example 3. In such cases, it has been found that even at fairly low lamination pressures (e.g., in the range of about 10 PLI-200 PLI), a local transfer layer occupying a relatively large angular arc can be achieved.

[0132] It should be understood that the above-described arrangements are exemplary, and based on the disclosure herein, a person of ordinary skill would be able to manipulate various parameters, including but not limited to lamination pressure, characteristics of the backing roll of the lamination nip, the presence or absence of a conformal support in the transfer stack used for lamination, etc., to manipulate the characteristics of the lamination process, such as facilitating the desired arrangement of a first local transfer functional layer and a second local transfer functional layer (e.g., a reflective layer).

[0133] It should be understood that the actual results of any actual lamination process will be statistical and will not necessarily produce a completely uniform set of retroreflective elements. For example, in some cases, it has been found that a second, more vigorous lamination step can provide a second partial lamination layer onto transparent microspheres that (e.g., because the microspheres are smaller in diameter and / or are more deeply embedded in the carrier web) did not receive the first partial lamination layer in the first, less vigorous lamination step. The presence of a few statistically small numbers of such microspheres with only a partial lamination layer (and, in some cases, a plurality of microspheres that may not receive any partial lamination layer at all) has not been found to unacceptably detract from the overall results disclosed herein.

[0134] Regardless of the exact nature of the processing steps, the arrangements described herein provide that a localized area of ​​a first preformed functional layer can be bonded to a portion of a protruding area of ​​transparent microspheres with sufficient strength to allow the localized area of ​​the first layer to be peeled (delaminated) from the remaining layers of the multilayer transfer stack, and also allow the localized area of ​​the first layer to be detached from the area of ​​the first layer that previously laterally surrounded the localized area. Similar considerations apply to the second preformed functional layer, noting that various parameters can be varied to modify the area coverage achieved by the second layer.

[0135] It has been found that various process conditions can also affect whether the second partial laminate layer is arranged purely as a spherical segment around the existing first partial laminate layer; or, is arranged so that a portion of the second layer remains in place behind the first layer. In other words, such an arrangement can affect whether the second layer consists only of a spherical segment arranged parallel to the first layer, or whether it also includes a portion arranged in series with the first layer (behind the first layer). In general, the properties of the last surface of the first partial laminate layer (as inherently exhibited by the layer itself, or as modified, for example, by a specific surface treatment) can affect the tendency of the second layer to remain in place against the rear of the first layer. It has also been found that the properties of the second layer can affect this tendency. For example, the thickness and / or stiffness of the second layer can play a role. In some cases, a thicker, harder and / or more difficult to break or crack second layer may have a greater tendency to hold a portion of the first layer backwards in place. This may be the case even if the second layer is not necessarily bonded to the first layer (strongly or not at all). Conversely, a second layer that is sufficiently thick and strong and that is bonded to the areas of the microspheres not covered by the first layer can hold a portion of the first layer back, even if that portion is not necessarily bonded to the first layer. In summary, therefore, the nature of the partial lamination process (e.g., whether any given lamination of the second partial lamination layer is a torus transfer process or a full transfer process) can be affected by the characteristics of the layers themselves, rather than just by the process conditions. Again, it should be understood that such phenomena can be statistical in nature, and in any given case, multiple configurations can exist.

[0136] It should be emphasized that many variations of the specific arrangements disclosed above are possible and can be used for specific applications. For example, the discussion so far has focused on situations where the first local laminate layer is relatively small (e.g., present in a polarizing cover configuration) and where the second local laminate layer is relatively large compared to the first layer (e.g., the second layer exists as a spherical segment that at least partially surrounds the first layer). However, in some embodiments, the first (e.g., frontmost) layer may be larger and the second (e.g., last) layer may be smaller. Although such an arrangement may provide little benefit, for example, if the first layer is a non-selective reflector such as silver or aluminum, in other embodiments, the first layer may be a dielectric stack that preferentially reflects a specific wavelength (e.g., near-infrared wavelength). Other wavelengths of light (e.g., visible light) may be allowed to pass through the first layer and then manipulated by the appropriately constructed second layer. In this general type of embodiment, if desired, the rearward surface of the first layer may be treated or otherwise configured to enhance the ability of the second layer to bond with it.

[0137] Regardless of the specific arrangement, in some embodiments, a suitable adhesive layer can be used to locally bond a local area of ​​the first layer or the second layer to the protruding area of ​​the transparent microsphere. In many embodiments, the intermediate layer 50 discussed elsewhere herein can be used as an adhesive layer, as long as the intermediate layer exhibits suitable adhesive properties. In various embodiments, the adhesive layer can be at least disposed on the top of the protruding area of ​​the microsphere and can be processed (e.g., softened) to any layer of organic polymer material sufficient to allow the functional layer to locally bond to the protruding area of ​​the microsphere. In some embodiments, this softening can occur by the local pressure applied in the lamination process (because the lamination pressure will be concentrated on the actual part of the microsphere contacted by the transfer stack). Therefore, in some embodiments, in order to perform the local lamination disclosed herein, it may not be necessary to provide an elevated temperature (e.g., by heating one or two of the backing rollers of the lamination nip). In such embodiments, lamination can be performed under ambient conditions, such as at a temperature in the range of about 20°C-22°C. In other embodiments, lamination at a high temperature may be helpful.

[0138] In some embodiments, the adhesive layer can be provided by an organic polymer material layer (e.g., an intermediate layer) disposed on at least a portion of the protruding region of the carrier-carrying transparent microsphere, and is configured so that under appropriate lamination conditions, the functional layer can be locally bonded thereto. Some such intermediate layers can be used for certain other purposes, such as these layers can be used as, for example, protective layers providing wear resistance, corrosion resistance, etc. Protective layers and compositions thereof that can be used as adhesive layers are described in detail in U.S. Patent Application Publication No. 2017 / 0276844, which is incorporated herein by reference in its entirety. In a specific embodiment, this layer can be made of polyurethane material. Various polyurethane materials that can be applicable to such purposes are described in U.S. Patent Application Publication No. 2017 / 0131444, which is incorporated herein by reference in its entirety.

[0139] In some embodiments, an adhesive layer that exhibits pressure-sensitive adhesive properties, for example, at room temperature, can be used. Such methods can provide a local lamination process that can be performed under relatively low lamination pressure. In some such embodiments, this pressure-sensitive adhesive can be arranged on at least a portion of the top of the protruding area of ​​the carrier-bearing microsphere, to form a local adhesive layer, for example, by a transfer process, such as flexographic printing of an adhesive precursor. In some specific embodiments of this type, this adhesive layer (for example, an adhesive layer of flexographic printing) can include a colorant. Therefore, this layer can be used as a local color layer as previously described herein, and can also be used as an adhesive layer for a local laminated layer.

[0140] In various embodiments, if such an adhesive layer is a separate layer from the above-described partial color layer, the adhesive layer can be disposed on top of the carrier-bearing transparent microspheres after the partial color layer is disposed on the adhesive layer. It should be understood that the partial lamination process encompasses the physical transfer of the functional layer to the protruding areas of the transparent microspheres, regardless of what layers already exist on the protruding areas of the microspheres.

[0141] In some embodiments, such an adhesive layer may be present in a continuous manner (e.g., including Figure 1 In other embodiments, such an adhesive layer may be a discontinuous adhesive layer that is present only in localized areas of the protruding areas of the transparent microspheres to which the functional layer is desired to be laminated. Such a discontinuous adhesive layer may be provided locally, for example, by flexographic printing or the like.

[0142] It should be noted that even if the adhesive layer is continuous rather than discontinuous, the lamination process can be performed such that the (first or second) prefabricated functional layer only contacts (and is thus transferred to) the areas of the adhesive layer that are actually contacted by the reflective layer.

[0143] After forming the first local laminated layer and the second local laminated layer, the binder can be arranged on the microsphere bearing carrier layer 110. In some embodiments, this can be performed by setting a binder precursor (for example, a mixture or solution of a binder layer component) to the microsphere bearing carrier layer 110. The binder precursor can be (for example, by coating) arranged on the carrier layer of the loaded microsphere, and then hardened to form a binder layer, for example, a continuous binder layer. The binder can be any suitable composition, and for example, the binder can be formed by a binder precursor including an elastomeric polyurethane composition and any desired additives. The binder composition, method, etc. of the binder manufactured by the precursor are described in U.S. Patent Application Publication 2017 / 0131444 and 2017 / 0276844, and these patent applications are incorporated herein by reference in their entirety. The binder, its composition and method of making the binder may also be selected from those described in U.S. Provisional Application No. 62 / 522279 and the corresponding PCT International Patent Application No. US2018 / 038160, U.S. Provisional Application No. 62 / 527090 and the corresponding PCT International Patent Application No. IB2018 / 054778, U.S. Provisional Application No. 62 / 785326 and U.S. Provisional Application No. 62 / 785344, all of which are incorporated herein by reference in their entirety.

[0144] Generally speaking, the binder layer 10 is configured to support transparent microspheres 21 and is generally a continuous, fluid-impermeable sheet layer. In various embodiments, the binder layer 10 may show an average thickness of 1 to 250 microns. In other embodiments, the binder layer 10 may show an average thickness of 30 to 150 microns. The binder layer 10 may include a polymer containing the following units, such as carbamate, ester, ether, urea, epoxy, carbonate, acrylate, acrylic acid, olefin, vinyl chloride, amide, alkyd or a combination thereof. A variety of organic polymers can be used to form reactants to form the polymer. Polyols and isocyanates can react to form polyurethanes; diamine compounds and isocyanates can react to form polyureas; epoxides can react with diamines or diols to form epoxy resins, and acrylate monomers or oligomers can be polymerized to form polyacrylates; and diacids can react with diols or diamine compounds to form polyesters or polyamides. Examples of materials that can be used to form the binder layer 10 include, for example: Vitel TM 3550, purchased from Bostik Inc., Middleton, MA; Ebecryl TM 230, purchased from UBC Radcure, Smyrna, GA; Jeffamine TM T-5000, available from Huntsman Corporation, Houston, TX; CAPA 720, available from Solvay Interlox Inc., Houston, TX; and Acclaim TM Lyondell Chemical Company, Houston, TX 8200.

[0145] In some embodiments, the binder layer 10 can be at least roughly visible transmissive (e.g., transparent). In many convenient embodiments, the binder layer 10 can include one or more coloring agents. In a specific embodiment, the binder can include one or more fluorescent pigments. Suitable coloring agents (e.g., pigments) can be selected from those listed in the '444 publication and the '844 publication cited above.

[0146] In some embodiments, the binder layer 10 may include reflective particles, such as flakes, of a reflective material (e.g., nacre or pearlescent material) such that at least a portion of the binder layer 10 adjacent to the transparent microspheres 21 may serve as a secondary reflective layer. By "second" reflective layer is meant a layer of the binder layer 10 that is used to enhance the performance of the retroreflective element above that provided by the first partially laminated reflective layer 30 and / or the second partially laminated reflective layer 530 covering the region 28 of the transparent microspheres. By definition, such a "second" reflective layer is not a partially laminated layer and is therefore distinguished from the first partially laminated reflective layer and the second partially laminated reflective layer previously described. In many embodiments, such a second reflective layer may be primarily adjacent to the portion of the embedded region 25 of the transparent microspheres 21 that is not covered by the first partially laminated reflective layer 30 or the second partially laminated reflective layer 530 (e.g., such as Figure 6 The second reflective layer is described in detail in U.S. Provisional Patent Application No. 62 / 739529 and PCT International Patent Application No. US2018 / 057558, both of which are incorporated herein by reference in their entirety.

[0147] This paper mainly discusses Figure 1 and Figure 6 30 and 530, or their equivalents, may be provided in an article that does not include an adhesive layer. For ease of description, such an article will be referred to as an "intermediate" article. Fig. 9 In this type of embodiment, the intermediate article 1000 will take the form of a carrier layer 110 carrying transparent microspheres 21 on its first surface 112 without any binder layer. (If desired, however, the transparent microspheres 21 may be protected, for example, by a removable cover film disposed on the microsphere-bearing side of the carrier layer.) Such an intermediate article will include at least some transparent microspheres 21 including protruding regions 25 providing localized laminate layers 30 and 530 on portions 28 thereof.

[0148] In some embodiments, the first layer 30 and / or the second layer 530 may form an embedded layer in the final product. However, strictly speaking, any such layer will not be an "embedded" layer before the presence of the binder layer 10. Therefore, in this particular type of embodiment, such layers will be equivalently characterized as "separate" layers, meaning that these reflective layers cover a portion of the protruding area 25 of the microspheres but not the entirety. In terms of microsphere coverage, corner arcs, etc., the various features of the local laminate layer will be understood to apply in a manner similar to the isolation layer in the intermediate product where the binder layer has not yet been set to form the final product.

[0149] In some embodiments, the intermediate article may include an intervening layer 50 of the general type described elsewhere herein. Other layers (eg, color layers) may be included in the intermediate article as desired.

[0150] The intermediate article, which includes the transparent microspheres having a barrier layer partially laminated thereon, can be further processed in any desired manner. In some embodiments, a binder layer, for example, including any desired colorant, can be disposed on the microsphere-bearing carrier layer to form article 1. The intermediate article can be shipped to a customer in any suitable configuration, who can, for example, configure a binder layer thereon to form a custom article.

[0151] The discussion herein relates primarily to retroreflective articles in which the area 24 of the microspheres 21 that is forwardly exposed (i.e., protruding) from the binder layer 10 is exposed to the ambient atmosphere (e.g., air) in the final retroreflective article in which it is used. In other embodiments, the exposed area 24 of the microspheres 21 may be covered by and / or reside within a cover layer that is a permanent component of the article 1. Such articles will be referred to as encapsulated lens retroreflective articles. In this case, the transparent microspheres may be selected to include a refractive index that is appropriately performed in combination with the refractive index of the cover layer. In various embodiments, in an encapsulated lens retroreflective article, the microspheres 21 may include a refractive index of at least 2.0, 2.2, 2.4, 2.6, or 2.8 (e.g., obtained by the material composition of the microspheres and / or by any type of surface coating present thereon). In some embodiments, the cover layer of the encapsulated lens retroreflective article may include a sublayer. In this case, the refractive indices of the microspheres and the sublayers may be selected in combination.

[0152] In some embodiments, such a covering layer may be a transparent layer. In other embodiments, the entire or selected areas of the covering layer may be colored as desired (e.g., may include one or more colorants). In some embodiments, the covering layer may take the form of a pre-existing film or sheet that is disposed (e.g., laminated) to at least a selected area of ​​the front side of the article 1. In other embodiments, the covering layer may be obtained by printing, coating, or otherwise depositing a covering layer precursor onto at least a selected area of ​​the front side of the article 1 and then converting the precursor into a covering layer.

[0153] As previously described herein, in some embodiments, a colored layer may exist, and wavelength selective absorption of electromagnetic radiation may be performed at least at a certain position in the range including visible light and infrared radiation by using a colorant arranged in the colored layer. Alternatively or in addition thereto, a colorant may be arranged in the binder layer 10. The term colorant broadly encompasses pigments and dyes. Routinely, a pigment is considered to be a colorant that is usually insoluble in a material in which a colorant is present, and a dye is considered to be a colorant that is usually soluble in a material in which a colorant is present. However, whether a colorant is presented as a pigment or a dye when being dispersed in a particular material may not always be clearly distinguished. Therefore, the term colorant encompasses any such material, and is considered to be independent of whether it is considered to be a dye or a pigment in a particular environment. Suitable colorants are described and discussed in detail in the above-mentioned U.S. Provisional Patent Application 62 / 675020.

[0154] The transparent microspheres 21 used in any of the articles disclosed herein can be of any suitable type. In this particular context, the term "transparent" is generally used to refer to a body (e.g., a glass microsphere) or substrate that transmits at least 50% of electromagnetic radiation at a selected wavelength or a selected wavelength range. In some embodiments, the transparent microspheres can transmit at least 75% of light in the visible light spectrum (e.g., from about 400 nm to about 700 nm); in some embodiments, at least about 80%; in some embodiments, at least about 85%; in some embodiments, at least about 90%; and in some embodiments, at least about 95%. In some embodiments, the transparent microspheres can transmit at least 50% of the radiation at a selected wavelength (or range) in the near infrared spectrum (e.g., from 700 nm to about 1400 nm). In various embodiments, the transparent microspheres can be made of, for example, inorganic glass, and / or can have a refractive index of, for example, 1.7 to 2.0. (As previously described, in a packaged lens arrangement, transparent microspheres may be selected to have a higher refractive index as desired.) In various embodiments, the microspheres may have an average diameter of at least 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, or 80 microns. In various embodiments, the microspheres may have an average diameter of at most 200 microns, 180 microns, 160 microns, 140 microns, 120 microns, 100 microns, 80 microns, or 60 microns. The shape of the vast majority (e.g., at least 90% by number) of the microspheres may be at least roughly, substantially, or essentially spherical. However, it should be understood that microspheres produced as in any realistic, large-scale process may include a small number of microspheres that exhibit slight deviations or irregularities in shape. Therefore, the use of the term "microsphere" does not require that the shape of these items must be, for example, perfectly or precisely spherical.

[0155] U.S. Patent Application Publications 2017 / 0276844 and 2017 / 0293056, which are incorporated herein by reference in their entirety, discuss the use of a method for determining the reflectivity of a material according to, for example, the coefficient of retroreflectivity (R A ) methods for characterizing retroreflectivity. In some embodiments, at least selected areas of the retroreflective articles disclosed herein may exhibit a coefficient of retroreflectivity of at least 20 candela / lux / m2, 50 candela / lux / m2, 100 candela / lux / m2, 200 candela / lux / m2, 250 candela / lux / m2, 350 candela / lux / m2, or 450 candela / lux / m2, measured according to the procedures outlined in these publications (at a 0.2 degree observation angle and a 5 degree incident angle). In some embodiments, when measured at a "front" angle of incidence (e.g., 5 degrees), R A In other embodiments, when measured at a "grazing" angle of incidence (e.g., 30, 40, or 50 degrees, or even 88.76 degrees), R A Can be the highest.

[0156] In various embodiments, the retroreflective articles as disclosed herein may meet the requirements of ANSI / ISEA 107-2015 and / or ISO 20471:2013 for minimum coefficient of retroreflection performance at specific combinations of incident angles and observation angles, such as a "32-angle" test cell of the type described in Table 5 of ISO 20471:2013 used in evaluating, for example, safety clothing. In many embodiments, the retroreflective articles as disclosed herein may exhibit satisfactory or excellent laundering durability. Such laundering durability may be manifested as high R after many (e.g., 25) laundering cycles performed according to the method of ISO 6330 2A. A Retention (after washing R A R before washing A ), as outlined in U.S. Patent Application Publication No. 2017 / 0276844. In various embodiments, a retroreflective article as disclosed herein may exhibit at least 30%, 50%, or 75% R after 25 such wash cycles. A In various embodiments, retroreflective articles as disclosed herein may exhibit any of these retroreflectivity retention characteristics with an R of at least 100 candelas / lux / m2 or 330 candelas / lux / m2 as measured as described above. A Combine.

[0157] The retroreflective articles disclosed herein can be used for any desired purpose. In some embodiments, the retroreflective articles as disclosed herein can be configured for use in or with systems that perform, for example, machine vision, remote sensing, surveillance, etc. Specifically, in many embodiments, the arrangements disclosed herein can provide retroreflective articles in which the wavelength dependence of retroreflectivity varies with the angle of incidence in a manner that is not possible (e.g., to some extent) with conventional uniformly reflecting microspheres, for example. Such behavior can be very advantageous for, for example, machine vision systems. Any such machine vision system can rely on, for example, one or more visible light and / or near infrared (IR) image acquisition systems (e.g., cameras) and / or radiation or illumination sources, as well as any other hardware and software required to operate the system. Therefore, in some embodiments, the retroreflective articles as disclosed herein (whether or not they are mounted on a substrate) can be components of or work in conjunction with machine vision systems of any desired type and configuration. Such retroreflective articles can, for example, be configured for optical interrogation (whether by visual wavelength or near infrared camera, for example, at a distance of up to a few meters, or even up to a few hundred meters), regardless of ambient light conditions. Thus, in various embodiments, such retroreflective articles may include retroreflective elements that are configured to collectively exhibit any suitable image, code, pattern, etc. that permits information carried by the article to be retrieved by a machine vision system. Exemplary machine vision systems, the manner in which retroreflective articles may be configured for use in such systems, and the manner in which retroreflective articles may be characterized with particular regard to their suitability for such systems are disclosed in U.S. Provisional Patent Application 62 / 536,654, which is incorporated herein by reference in its entirety.

[0158] In some embodiments, local laminated layers (e.g., reflective layers), colored layers, etc. may be disposed in various macroscopic regions of a retroreflective article, rather than collectively occupying the entire article. Such an arrangement may allow an image to be visible in retroreflected light (whether such an image is highlighted by increased retroreflectivity and / or by enhanced color). In some embodiments, such an image may be achieved, for example, by performing patterned deposition of a local laminated reflective layer in a lamination process, for example, by using a patterned lamination roller or a patterned conformable substrate. In various embodiments, a retroreflective article as disclosed herein may be configured to display an image when viewed in retroreflected light, to display an image when viewed in ambient light, or both. If both are present, the image when viewed in ambient light may be substantially the same as the image when viewed in retroreflected light (e.g., the article may convey the same information in both cases); or the two images may be different (e.g., so that different information is conveyed in ambient light and retroreflected light).

[0159] Various components of retroreflective articles (e.g., transparent microspheres, binder layers, reflective layers, etc.), methods of making such components, and incorporating such components into retroreflective articles in various arrangements are described, for example, in U.S. Patent Application Publication Nos. 2017 / 0131444, 2017 / 0276844, and 2017 / 0293056, and U.S. Provisional Patent Application No. 62 / 578343, all of which are incorporated herein by reference in their entirety.

[0160] It should be understood that retroreflective elements including a first partial laminate layer and a second partial laminate layer as disclosed herein can be used in any retroreflective article of any suitable design and any suitable application. In particular, it should be noted that the presence of retroreflective elements including transparent microspheres (and one or more color layers, reflective layers, etc.) does not preclude the presence of other retroreflective elements (e.g., so-called cube corner retroreflectors) somewhere in the article that do not include transparent microspheres.

[0161] Although the discussion herein relates primarily to the use of the retroreflective articles described herein with apparel and similar articles, it should be understood that these retroreflective articles may find use in any application, such as mounted to or present on or near any suitable article or entity. Thus, for example, retroreflective articles as disclosed herein may find use in road marking tapes, road signs, vehicle markings or identification (e.g., license plates), or generally in any kind of reflective sheeting. In various embodiments, such articles and sheeting including such articles may present information (e.g., indicia), may provide an aesthetic appearance, or may provide a combination of both uses.

[0162] Exemplary embodiments

[0163] The disclosure presented herein includes, but is not limited to, the following exemplary embodiments, arrangements, and combinations.

[0164] Embodiment 1 is a retroreflective product, which includes: a binder layer; and a plurality of retroreflective elements, which are spaced apart in length and width on the front side of the binder layer, each of which includes transparent microspheres partially embedded in the binder layer so as to display the embedded area of ​​the transparent microspheres; wherein at least some of the retroreflective elements each include a first partial laminate layer, which is embedded between the transparent microspheres and the binder layer; and a second partial laminate layer, which is embedded between the transparent microspheres and the binder layer.

[0165] Embodiment 2 is a retroreflective article according to embodiment 1, wherein the first partially laminated embedded layer and / or the second partially laminated embedded layer is a reflective layer. Embodiment 3 is a retroreflective article according to embodiment 2, wherein the first partially laminated embedded layer is a first reflective layer, and wherein the second partially laminated embedded layer is a second reflective layer. Embodiment 4 is a retroreflective article according to any of embodiments 1-3, wherein at least 50% of the retroreflective elements of the retroreflective article each include a first partially laminated embedded reflective layer and / or a second partially laminated embedded reflective layer.

[0166] Embodiment 5 is a retroreflective article according to any one of embodiments 3-4, wherein at least some of the first partially laminated embedded reflective layer is a partial layer, and at least some of the second partially laminated embedded reflective layer is a partial layer.

[0167] Embodiment 6 is a retroreflective article according to any one of embodiments 1-5, wherein for at least some of the microspheres on which the first partial laminated embedding layer and the second partial laminated embedding layer are present, at least a portion of the second partial laminated embedding layer is arranged parallel to the first partial laminated embedding layer so that incident light can reach the parallel portion of the second partial laminated embedding layer without having to pass through any portion of the first partial laminated embedding layer.

[0168] Embodiment 7 is a retroreflective article according to any of embodiments 1-6, wherein for at least some of the microspheres on which the first and second partially laminated embedded layers are present, at least a portion of the second partially laminated embedded reflective layer is arranged behind the first partially laminated embedded layer and in series with the first partially laminated embedded layer, so that incident light must pass through the first partially laminated embedded layer to reach the series portion of the second partially laminated embedded layer.

[0169] Embodiment 8 is a retroreflective article according to any one of embodiments 1-7, wherein for the microspheres on which the first and second partial laminated embedded layers are present, the first and second partial laminated embedded layers each occupy an angular arc of at most 180 degrees. Embodiment 9 is a retroreflective article according to any one of embodiments 1-8, wherein for at least some of the microspheres on which the first and second partial laminated embedded layers are present, the first partial laminated embedded layer occupies an angular arc of less than 40 degrees, and the second partial laminated embedded layer occupies an angular arc of greater than 60 degrees.

[0170] Embodiment 10 is a retroreflective article according to any one of embodiments 1-9, wherein at least some of the partially laminated embedded layers each include a selective bonding layer. Embodiment 11 is a retroreflective article according to any one of embodiments 1-10, wherein at least some of the partially laminated embedded layers each include an embrittled layer.

[0171] Embodiment 12 is a retroreflective article according to any one of embodiments 1-11, wherein at least some of the partially laminated embedded layers are reflective layers that each include a metal reflective layer. Embodiment 13 is a retroreflective article according to any one of embodiments 1-12, wherein at least some of the partially laminated embedded layers are wavelength selective reflective layers that exhibit a predetermined peak reflection wavelength. Embodiment 14 is a retroreflective article according to any one of embodiments 1-13, wherein the first partially laminated embedded layers are first reflective layers that each include a metal reflective layer, and wherein the second partially laminated embedded layers are wavelength selective reflective layers that exhibit a predetermined peak reflection wavelength. Embodiment 15 is a retroreflective article according to any one of embodiments 1-13, wherein the first partially laminated embedded layers are first reflective layers that each include a metal reflective layer, and wherein the second partially laminated embedded layers are wavelength selective reflective layers that exhibit a predetermined peak reflection wavelength. Embodiment 15 is a retroreflective article according to any one of embodiments 1-13, wherein the first partially laminated embedded layers are first wavelength selective reflective layers that exhibit a first predetermined peak reflection wavelength; and, wherein the second partially laminated embedded layers are second wavelength selective reflective layers that exhibit a second predetermined peak reflection wavelength, and wherein the second predetermined peak reflection wavelength differs from the first predetermined peak reflection wavelength by at least 50 nm.

[0172] Embodiment 16 is a retroreflective article according to any one of embodiments 1-15, wherein at least the second partially laminated embedded layer is a reflective layer, and wherein the first partially laminated embedded layer and the second partially laminated embedded reflective layer are constructed so that at least at a wavelength between 400nm and 700nm, the retroreflective article exhibits a retroreflection percentage at an incident angle of 30 degrees that is at least 2% greater than the retroreflection percentage exhibited at an incident angle of 5 degrees.

[0173] Embodiment 17 is a retroreflective article according to any one of embodiments 1-16, wherein at least some of the retroreflective elements include an intermediate layer, at least a portion of which is disposed between the transparent microspheres and the binder layer, so that the first partial laminated embedded layer and the second partial laminated embedded layer are arranged behind the intermediate layer and between the intermediate layer and the binder layer.

[0174] Embodiment 18 is the retroreflective article of any one of embodiments 1-17, wherein the binder layer comprises a colorant.

[0175] Embodiment 19 is a transfer article comprising the retroreflective article of any one of embodiments 1-18 and a disposable carrier layer, on which the retroreflective article is removably provided with at least some transparent microspheres in contact with the disposable carrier layer. Embodiment 20 is a substrate comprising the retroreflective article of any one of embodiments 1-18, wherein the adhesive layer of the retroreflective article is coupled to the substrate, wherein at least some of the retroreflective elements of the retroreflective article face away from the substrate.

[0176] Embodiment 21 is an intermediate product, the intermediate product comprising: a disposable carrier layer having a major surface; a plurality of transparent microspheres partially embedded in the disposable carrier layer such that the transparent microspheres exhibit a protruding surface region; wherein at least some of the transparent microspheres each comprise a first partially laminated release layer present on a portion of the protruding surface region of the transparent microsphere and a second partially laminated release layer present on a portion of the protruding surface region of the transparent microsphere. Embodiment 22 is an intermediate product according to embodiment 21, wherein the first partially laminated release layer is a reflective layer and the second partially laminated release layer is a reflective layer.

[0177] Embodiment 23 is a method of making an intermediate product including a plurality of transparent microspheres, at least some of the plurality of transparent microspheres including a first preformed partially laminated barrier layer and a second preformed partially laminated barrier layer, the method comprising the steps of: contacting a region of the first preformed layer with a portion of a protruding region of at least some of the transparent microspheres, the at least some of the transparent microspheres being carried by a carrier layer and partially embedded in the carrier layer; physically transferring a region of the first preformed layer to a portion of the protruding region of the transparent microspheres that is in contact with the region of the first preformed layer, such that the transferred region of the first preformed layer is bonded to the portion of the protruding region of the transparent microspheres; wherein during the physical transfer process, the physically transferred region of the first preformed layer The method of claim 23 is to separate the area of ​​the first preformed layer that previously laterally surrounds the physical transfer area from the area of ​​the first preformed layer; and then to contact the area of ​​the second preformed layer with a portion of the protruding area of ​​at least some transparent microspheres carrying the first partially laminated isolation layer, wherein the at least some transparent microspheres are carried by a carrier layer and partially embedded in the carrier layer; and to physically transfer the area of ​​the second preformed layer to the portion of the protruding area of ​​the transparent microspheres that is in contact with the area of ​​the second preformed layer, so that the transferred area of ​​the second preformed layer is bonded to the portion of the protruding area of ​​the transparent microspheres carrying the first partially laminated isolation layer; wherein during the physical transfer process, the physically transferred area of ​​the second preformed layer is separated from the area of ​​the second preformed layer that previously laterally surrounds the physical transfer area. Embodiment 24 is a method according to embodiment 23, wherein the first partially laminated isolation layer and / or the second partially laminated isolation layer is a reflective layer.

[0178] Embodiment 25 is a method for manufacturing a retroreflective article from an intermediate product according to any one of embodiments 21-22, the method comprising: disposing a binder precursor on a carrier layer and on a protruding area of ​​transparent microspheres carrying a first partial laminated isolation layer and a second partial laminated isolation layer; and curing the binder precursor to form a retroreflective article including a binder layer, and wherein the first partial laminated isolation layer and the second partial laminated isolation layer are embedded between the transparent microspheres and the binder layer.

[0179] Example

[0180] The materials, preparation methods, and testing methods used in the following examples generally follow those used in U.S. Provisional Patent Application No. 62 / 739506 and PCT International Patent Application No. US2018 / 057553. It is also noted that the working examples presented in these applications (involving a single local laminate layer, rather than multiple local laminate layers as in the present case) further illustrate the lamination methods relied upon in this case and contain further discussion of the characterization of the local laminate layers (and specifically, for example, their appearance when observed via an optical microscope or a scanning electron microscope). For all of these reasons, the '506 patent application and the '553 patent application are incorporated herein by reference in their entirety.

[0181] Test Method

[0182] Retroreflection coefficient

[0183] Reflectance under ambient light conditions (Y, x, y) (R at an observation angle of 0.2° and an incident angle of 5°) A ) and color coordinates follow the same test methods as described in the '506 patent application cited above. In some cases, samples are evaluated in a "32-angle" test cell of the type described in Table 5 of ISO 20471:2013 (also known as ANSI / ISEA 107-2015) and is commonly used to evaluate, for example, safety apparel.

[0184] Retroreflection spectrum measurement

[0185] The radiant properties of the retroreflected light of the retroreflective material were measured with an Ocean Optics spectrometer (Model FLAME-S-VIS-NIR), a light source (Model HL-2000-FHSA) and a reflectance probe (Model QR400-7-VIS-BX) at an observation angle of 0.2° and an incident angle of 5°, 20°, 30° or 40°, over a 0.5 inch diameter sample area with an integration time of 4 milliseconds. The radiant properties of the retroreflected light of the retroreflective material were measured with an Ocean Optics spectrometer (Model FLAME-S-VIS-NIR), a light source (Model HL-2000-FHSA) and a reflectance probe (Model QR400-7-VIS-BX) at an observation angle of 0.2° and an incident angle of 5°, 20°, 30° or 40°, over a TMDiamond Grade TM DG3 Prismatic Digital Sheeting 4090DS (white) sheeting calibrates retroreflected light. The retroreflected spectrum is shown as the percent reflectance (Retroreflection R%) in the wavelength range of 400 nm to 1000 nm.

[0186] Preparatory product and method for manufacturing the same

[0187] Method for making a temporary bead carrier comprising glass microspheres

[0188] The fabrication of the temporary support sheet bearing the transparent microspheres follows the same general procedure outlined in the "Method for Fabricating a Temporary Bead Support Containing Glass Microspheres" section of the '506 patent application. An organic polymer layer is disposed on the microsphere bearing support following the same general procedure as described in the first paragraph of Working Example 2.3.1.D (Section D) of the '506 patent application. The resulting article is referred to as a polymer-coated bead support.

[0189] Method for producing a multilayer transfer stack including a reflective layer

[0190] Fabrication of transfer stacks including reflective layers in the form of dielectric stacks follows the same general procedure as described in Working Example 2.3.3A (Section A) of the '506 patent application. Two such transfer stacks were fabricated, one (designated R3502-5) including a dielectric stack reflective layer targeted for a wavelength of maximum reflection in the visible range, and the other (designated R3512) including a dielectric stack reflective layer targeted for a wavelength of maximum reflection in the near infrared range. (For convenience, these terms may be referred to herein by the abbreviations of visible light reflection and near infrared reflection.) The configurations of the two transfer stacks are shown in Tables 1 and 2. In these tables, all sublayer thicknesses are nominal targets based on measurements or estimates of deposition rates; in addition, the sublayers listed as "acrylate stripping" in these and other tables correspond to sublayers of the general type designated as "acrylate-1" in the '506 and '553 patent applications cited above.

[0191] Table 1 – Transfer Stack R3502-5

[0192]

[0193] Table 2 – Transfer Stack R3512

[0194]

[0195] Comparative Example

[0196] Comparative Example 1 was made by laminating a transfer stack R3502-5 to a polymer-coated bead carrier. Lamination was performed using a pair of 16-inch diameter smooth steel rollers at a line speed of 3 feet per minute (fpm) and a lamination pressure of 1000 pounds per linear inch (PLI) (unless otherwise specified, these and all other laminations were performed at ambient temperature). The reflective layer of the transfer stack appeared to be well bonded to the organic polymer layer present on the protruding surface of the beads and separated from the surrounding reflective layer to achieve the local lamination described herein. After the lamination process, both the untransferred reflective layer and the sacrificial layer of the transfer stack (including the SiAl release layer and the PET substrate) were removed from the microsphere-bearing carrier. A binder layer was then formed on the microsphere-bearing carrier in a manner generally similar to that of Section C of Working Example 2.4.1 of the '506 patent application. For convenience, the temporary carrier sheet is typically left in place on the article until the article is tested, at which time the carrier sheet is removed and discarded. The resulting retroreflective article, which is targeted for retroreflectivity in the visible wavelength range, is designated Comparative Example 1.

[0197] Comparative Example 2 was made in a similar manner to Comparative Example 1, except that transfer stack R3512 was used. Lamination conditions were the same. The retroreflective article targeted for retroreflectivity in the near infrared wavelength range was designated Comparative Example 2.

[0198] Working Example 1

[0199] In the first lamination process, the first transfer stack (R3512, including the near infrared reflective layer) was laminated to the polymer coated bead carrier. Lamination was performed using a pair of 16-inch diameter smooth steel rollers at a line speed of 3 feet per minute (fpm) and a lamination pressure of 800 pounds per linear inch (PLI). After the first lamination process, both the untransferred reflective layer and the sacrificial layer of the transfer stack were removed from the microsphere bearing carrier. The resulting article was then subjected to a second subsequent lamination process.

[0200] In a second subsequent lamination process, a second transfer stack (R3502-5, including a visible reflective layer) is laminated to the above product of the first lamination process. The lamination is performed using a pair of 16-inch diameter smooth steel rollers at a line speed of 3 feet per minute (fpm) and a lamination pressure of 1500 pounds per linear inch (PLI). After the lamination process, both the untransferred reflective layer and the sacrificial layer of the transfer stack are removed from the microsphere bearing support. A binder layer is then formed on the microsphere bearing support in a manner generally similar to that of Section C of Working Example 2.4.1 of the '506 patent application. For convenience, the temporary carrier sheet is typically left in place on the article until the article is tested, at which time the carrier sheet is removed and discarded.

[0201] The resulting retroreflective article is designated as Working Example 1. Working Example 1 is believed to include a majority of transparent microspheres on which a first near-infrared reflective layer is disposed in a relatively small polarizing cover configuration resulting from a first relatively low-pressure lamination process. A majority of the transparent microspheres also appear to have been provided with a second visible light reflective layer resulting from a second, more forceful (higher pressure) lamination process. The second visible reflective layer is believed to exist as a relatively large spherical segment that at least approximately circumscribes the first near-infrared reflective polarizing cover layer. It appears that, in most cases, the second reflective layer is not significantly bonded to the exposed rearward surface of the first reflective layer and is not held in place behind the first reflective layer. In other words, it appears that under these particular conditions, the second reflective layer exists primarily as a spherical segment arranged parallel to the first reflective layer, and the second reflective layer appears to have a significant portion arranged in series with the first reflective layer.

[0202] Retroreflectivity of working example 1 relative to comparative examples 1 and 2

[0203] For Comparative Examples 1 and 2 and for Working Example 1, retroreflection spectra (retroreflection R% as a function of wavelength and as a function of the angle of incidence of the incident light) were obtained by the procedure outlined above. The respective results are shown in Fig.10 , 11 and 12 in.

[0204] Fig.10 The detection of reveals that Comparative Example 1 exhibits a peak reflection wavelength at about 580 nm, which is within the target range for the particular dielectric stack used in the sample. In addition, the peak reflection wavelength does not change significantly when the incident angle changes from 5 degrees to 20 degrees and then to 30 degrees. These results indicate that the wavelength selectivity of the sample is independent of the incident angle of the incident light within this range of incident angles. In addition, the reflectivity decreases rapidly with increasing incident angle, indicating that a (single) reflective layer is present in the general type of polarization cover configuration previously described herein.

[0205] Fig.11 Inspection of the results revealed that Comparative Example 2 exhibited a peak reflection wavelength at approximately 900 nm, which is within the target range for the particular dielectric stack used in this sample. In addition, the peak reflection wavelength did not change significantly when the incident angle changed from 5 degrees to 20 degrees and then to 30 degrees. These results indicate that the wavelength selectivity of this sample is independent of the incident angle of incident light within this range. (Similarly, the reflection decreases rapidly with increasing incident angle, indicating that the reflective layer is present in the general type of polarizing cover configuration described previously herein.)

[0206] Fig.12The detection of (Working Example 1) reveals that the peak reflection wavelength at about 900nm is exhibited at an incident angle of 5 degrees. Very little reflection is observed in the visible range (e.g., a retroreflection R% of 4-5 at 550nm-600nm). As the incident angle increases to 20 degrees and then to 30 degrees, the near-infrared retroreflectivity decreases sharply, while the visible retroreflectivity increases sharply. These results indicate that the wavelength selectivity depends on the incident angle of the incident light. This behavior indicates microspheres with polarized cover near-infrared reflectors that dominate retroreflectivity at near-frontal incident angles of, for example, 5 degrees, and microspheres with spherical segment visible light reflectors that exert an increasing effect at higher incident angles of, for example, 30 degrees.

[0207] It is noteworthy that for Working Example 1, the retroreflection R% in the range of 400 nm-700 nm when measured at an incident angle of 30 degrees is actually higher than the retroreflection R% when measured at an incident angle of 5 degrees.

[0208] Comparative Example 3

[0209] Comparative Example 3 was prepared following a procedure similar to that described in the above-referenced '506 patent application for working example 2.4.1 using a transfer stack including a silver reflective layer constructed as shown in Table 3. (The combination of Al release layer and 1 mil BOPP substrate listed in the table corresponds to the "Heat Seal Film-1" referred to in the above-referenced '506 and '553 patent applications.)

[0210] Table 3 - Transfer stack with silver reflective layer

[0211]

[0212] The transfer stack is laminated to a polymer-coated bead carrier. In a process somewhat different from that described in Section B of Example 2.4.1 of the '506 patent application, lamination is performed at 30 fpm (12.6 mm / sec) and using a backing roller equipped with a silicone rubber sleeve of 68A Shore hardness. The lamination nip pressure is about 500 PLI. The silver reflective layer of the transfer stack appears to be well bonded to the organic polymer layer present on the protruding surface of the beads and is separated from the surrounding reflective layer to achieve the local lamination described herein. After the lamination process, both the untransferred reflective layer and the sacrificial layer of the transfer stack are removed from the microsphere-bearing carrier. Then, in a manner roughly similar to Section C of Working Example 2.4.1 of the '506 patent application, a binder layer is formed on the microsphere-bearing carrier. For convenience, the temporary carrier sheet is usually left in place on the article until the article is tested, at which time the carrier sheet is removed and discarded. The resulting retroreflective article including a broad-spectrum non-selective silver reflector layer is designated as Comparative Example 3.

[0213] Working Example 2

[0214] Working Example 2 was prepared by the following process. In a first lamination process, a transfer stack having the silver reflective layer described in Table 3 above was laminated to a polymer coated bead support in a manner generally similar to Comparative Example 3. After the first lamination process, both the untransferred reflective layer and the sacrificial layer of the transfer stack were removed from the microsphere bearing support.

[0215] In a second subsequent lamination process, a second transfer stack (the previously described visible light reflective transfer stack R3502-5) is laminated to the above product of the first lamination process. The lamination is performed using a pair of 16-inch diameter smooth steel rollers at a line speed of 3 feet per minute (fpm) and a lamination pressure of 1000 pounds per linear inch (PLI). After the lamination process, both the untransferred reflective layer and the sacrificial layer of the transfer stack are removed from the microsphere bearing support. A binder layer is then formed on the microsphere bearing support in a manner generally similar to that of Section C of Working Example 2.4.1 of the '506 patent application. For convenience, the temporary carrier sheet is typically left in place on the article until the article is tested, at which time the carrier sheet is removed and discarded.

[0216] The resulting retroreflective article was designated Working Example 2.

[0217] Working Example 2 is believed to include a plurality of transparent microspheres on which is disposed a first reflective layer, which is a relatively small polarizing cap-configured silver layer (providing broad spectrum, non-selective reflectivity) produced by a first relatively low pressure lamination process. Most of the transparent microspheres also appear to have been provided with a second reflective layer produced by a second, more vigorous (higher pressure) lamination process. These layers (which are dielectric stacks tailored for maximum reflection visible wavelengths) are believed to include at least some spherical segments that at least approximately circumscribe the first silver reflective polarizing cap layer.

[0218] Retroreflectivity of working example 2 relative to comparative example 3

[0219] Working Example 2 and Comparative Example 3 were tested in a "32-angle" retroreflectivity test of the type described in the '506 patent application. In this test, retroreflectivity (R) is measured at various angles of incidence (5 degrees to 40 degrees) and observation angles (0.2 degrees to 1.5 degrees). A Although not repeated herein, this test shows that Working Example 2 consistently exhibits significantly higher retroreflectivity at higher incident angles than Comparative Example 3. For example, when the observation angle is 0.2 to 1.5 degrees and the incident angle is 30 degrees, the R of Working Example 2 is A Compared with R of Comparative Example 3 AThe ratios of are in the range of 3-5, significantly above 1. The results are consistent with the presence of a "parallel" portion of the second visible light reflecting layer, which covers the microspheres at a larger angular arc than the first silver reflecting layer. It is also noted that Working Example 2 exhibits generally greater retroreflectivity than that exhibited by Comparative Example 3 in more frontal measurements (e.g., at an incident angle of 5 degrees), although to a lesser extent (e.g., a ratio range of 1.2–1.4). It is believed that this indicates that the second lamination process, which is more aggressive than the first lamination process, may have successfully transferred the second visible reflective layer (including the dielectric stack) to some relatively small number of transparent microspheres that have been subjected to the first lamination process without having a reflective layer transferred thereto. Working Example 2 exhibits the above-mentioned enhanced retroreflectivity (at relatively frontal angles, especially at higher incident angles, as described above) without unduly sacrificing color performance. Specifically, Working Example 2 exhibited Y, x, and y values ​​of 92, 0.37, and 0.52, which were excellent results close to the Y, x, and y values ​​(103, 0.38, and 0.53) exhibited by Comparative Example 3 (indicating a bright (fluorescent yellow) color).

[0220] Comparative Example 4

[0221] Comparative Example 4 was prepared using a transfer stack including a silver reflective layer constructed as shown in Table 4, following a procedure similar to that described in the above-referenced '506 Patent Application for Working Example 2.4.1.

[0222] Table 4 - Transfer stack with silver reflective layer

[0223]

[0224] The transfer stack was laminated to the polymer coated bead carrier following the same process as described in Comparative Example 3. The silver reflective layer of the transfer stack appeared to be well bonded to the organic polymer layer present on the protruding surface of the beads and separated from the surrounding reflective layer to achieve the localized lamination described herein. After the lamination process, both the untransferred reflective layer and the sacrificial layer of the transfer stack were removed from the microsphere bearing carrier to form a microsphere bearing carrier with a silver reflector.

[0225] A fluorescent yellow binder layer was prepared in a manner generally similar to Example 12 of U.S. Provisional Application No. 62 / 785344 cited above. 51 weight percent (wt.%) of a copolymer (based on styrene and isoprene with a styrene content of 22%, commercially available as Kraton D1119 from Kraton Corporation, Houston, Texas), 34 weight percent of a tackifier (commercially available as Westerz 5206 from Ingevity, North Charleston, South Carolina), and 15 weight percent of a fluorescent lime-yellow pigment powder (supplied as GT-17 SATURN YELLOW by Day Glo Color Corporation, Cleveland, Ohio) were charged into a twin-screw extruder and mixed in the extruder at 182° C. for 3 minutes. The mixed composition was then extruded using a contact die onto a virgin PET release liner at a coating thickness of approximately 0.101 millimeters (mm) and then covered with a silicone coated release liner.

[0226] A white adhesive layer was prepared in a manner generally similar to Example 12 of the '344 patent application. 51 wt% of a copolymer (based on styrene and isoprene with a styrene content of 22%, commercially available as Kraton D1119 from Kraton Corporation, Houston, Texas), 34 wt% of a tackifier (commercially available as Westerz 5206 from Ingevity, North Charleston, South Carolina), and 15 wt% of a white pigment powder (commercially available as Dupont Ti-Pure R900 from The Chemours Company, Wilmington, DE) were charged into a twin-screw extruder and mixed in the extruder at 182° C. for 3 minutes. The mixed composition was then extruded onto a virgin PET release liner using a contact die at a coating thickness of approximately 0.101 mm and then covered with a silicone-coated release liner.

[0227] White fabric was purchased from Milliken & Co., Spartanburg, SC.

[0228] A stack was thus prepared (after removing the release liner from the adhesive layer) comprising the following layers: white fabric, white adhesive layer, fluorescent yellow adhesive layer, and microsphere-bearing carrier (wherein the microspheres bear a silver reflector layer as described above). The stack was laminated for 20 seconds at 163° C. and 40 pounds per square inch (PSI) using a Hix N-800 clamshell laminator. For convenience, a temporary carrier sheet is typically left in place on the article until the article is tested, at which time the carrier sheet is removed and discarded. The resulting retroreflective article including a broad spectrum non-selective silver reflector layer is designated Comparative Example 4.

[0229] Working Example 3

[0230] A transfer stack (designated R3518-3) including a visible reflective layer in the form of a dielectric stack was prepared according to the same general procedure as described in Working Example 2.3.3A (Part A) of the '506 patent application, resulting in the configuration shown in Table 5. A three-layer elastomeric transfer adhesive film was prepared according to the same procedure as described in Working Example 2.3.1.B (Part B) of the '506 patent application. Using an Akiles ProLam Plus 330 13" bag laminator (MiraLoma) set at 77°C, the three-layer elastomeric transfer adhesive was laminated to the transfer stack R3518-3 so that the NbOx surface was in contact with the elastomeric transfer adhesive surface. The sacrificial layer of the transfer stack was then removed from the construction to form an elastomeric transfer adhesive with a weakly bonded visible reflective layer.

[0231] Table 5 - Transfer Stack R3518-3

[0232]

[0233] Working Example 3 was prepared by the following process. In a first lamination process, a transfer stack having the silver reflective layer described in Table 4 above was laminated to a polymer coated bead support in a manner generally similar to Comparative Example 4. After the first lamination process, both the untransferred reflective layer and the sacrificial layer of the transfer stack were removed from the microsphere bearing support.

[0234] In a second subsequent lamination process, an elastomeric transfer adhesive having a weakly bonded visible light reflective layer was laminated onto the above product of the first lamination process at a lamination pressure of 40 PLI at 82° C. The elastomeric transfer adhesive film was then removed from the microsphere-bearing carrier to form a microsphere-bearing carrier having a first silver reflector and a second visible light reflector.

[0235] A stack was thus prepared (after removing the release liner from the adhesive layer) comprising the following layers: white fabric, white adhesive layer, fluorescent yellow adhesive layer, and microsphere-bearing carrier (wherein the microspheres bear the first and second reflectors as described above). The stack was laminated for 20 seconds at 163° C. and 40 PSI using a Hix N-800 clamshell laminator. For convenience, a temporary carrier sheet is typically left in place on the article until the article is tested, at which time the carrier sheet is removed and discarded. The resulting retroreflective article comprising a first broad spectrum non-selective silver reflector layer and a second visible light reflector layer is designated as Working Example 3.

[0236] Thus, working example 3 has a substantially similar structure to working example 2, wherein a significant number of transparent microspheres comprise a first reflector layer, which is a broad spectrum non-selective silver layer; and a second reflector layer, which exhibits preferential reflection at a specific visible wavelength. The difference between the two working examples is that the second reflector of working example 3 is formed by a lamination process assisted by a conformal elastomeric substrate (referred to as an elastomeric transfer adhesive in the examples) at a relatively low lamination pressure; whereas the second reflector of working example 2 is produced by lamination between steel rollers at a relatively high lamination pressure.

[0237] Retroreflectivity of working example 3 relative to comparative example 4

[0238] Working Example 3 (and Comparative Example 4) were also subjected to a 32-angle retroreflectivity test of the type described above for Working Example 2. It was found that the R of Working Example 3 and Comparative Example 4 at an incident angle of 40 degrees (and an observation angle of 0.2 degrees to 1.5 degrees) was 2.34°. A The ratio is in the range of 8-21. This is significantly higher than the R of the above working example 2 and comparative example 3. A The ratio of the incident angle to the observation angle is less than 2.5. Thus, compared to Working Example 2, Working Example 3 exhibits enhanced retroreflectivity retention at relatively high incident angles (e.g., up to 40 degrees). This demonstrates the ability of elastomer-assisted lamination to place a reflector on the microspheres at relatively high "wrap" angles without using extremely high pressures.

[0239] The above examples are provided only for a clear understanding of the present invention and should not be construed as unnecessary limitations. The tests and test results described in the examples are intended to be illustrative rather than predictive, and variations in the test procedures can be expected to yield different results. All quantitative values ​​in the examples are to be construed as approximate values ​​based on the commonly known tolerances involved in the process used.

[0240] It will be apparent to those skilled in the art that the specific exemplary elements, structures, features, details, configurations, etc. disclosed herein can be modified and / or combined in many embodiments. The inventors expect that all such variations and combinations are within the scope of the conceived invention, not just those representative designs selected as exemplary illustrations. Therefore, the scope of the present invention should not be limited to the specific illustrative structures described herein, but should at least be extended to the structures described by the language of the claims and the equivalents of these structures. Any element cited positively as an alternative in this specification may be explicitly included in the claims or excluded from the claims in any combination as required. Any element or combination of elements cited in this specification with open language (e.g., including and its derivatives) is considered to be quoted in closed language (e.g., consisting of ... and its derivatives) and in part of closed language (e.g., substantially consisting of ... and its derivatives). Although various theories and possible mechanisms may have been discussed herein, such discussions should not be used to limit the subject matter that can be protected by the claims in any case. If there is any conflict or contradiction between the disclosure of this specification as written and any document incorporated herein by reference, the written specification shall prevail.

Claims

1. A retroreflective article comprising: Adhesive layer; and, a plurality of retroreflective elements spaced apart across the length and width of the front side of the binder layer, each retroreflective element comprising transparent microspheres partially embedded in the binder layer so as to display the embedded area of ​​the transparent microspheres; wherein at least some of the retroreflective elements each include a first partial laminate layer, the first partial laminate layer being embedded between the transparent microspheres and the binder layer; and a second partial laminate layer, the second partial laminate layer being embedded between the transparent microspheres and the binder layer; wherein the first partial laminate layer and the second partial laminate layer are both present as discrete entities; and Wherein, for at least some of the microspheres on which the first local laminated embedding layer and the second local laminated embedding layer are present, at least a portion of the second local laminated embedding layer is arranged parallel to the first local laminated embedding layer so that incident light can reach the parallel portion of the second local laminated embedding layer without having to pass through any portion of the first local laminated embedding layer.

2. The retroreflective article of claim 1, wherein the first partially laminated embedded layer and / or the second partially laminated embedded layer is a reflective layer.

3. The retroreflective article of claim 2, wherein the first partially laminated embedded layer is a first reflective layer, and wherein the second partially laminated embedded layer is a second reflective layer.

4. The retroreflective article of claim 3, wherein at least 50% of the retroreflective elements of the retroreflective article each comprise a first partially laminated embedded reflective layer and / or a second partially laminated embedded reflective layer.

5. The retroreflective article of claim 3, wherein at least some of the first partially laminated embedded reflective layers are partial layers, and at least some of the second partially laminated embedded reflective layers are partial layers.

6. The retroreflective article of claim 1, wherein for at least some of the microspheres on which the first and second partially laminated embedded layers are present, at least a portion of the second partially laminated embedded reflective layer is disposed behind and in series with the first partially laminated embedded layer such that incident light must pass through the first partially laminated embedded layer to reach the series portion of the second partially laminated embedded layer.

7. The retroreflective article of claim 1 wherein, for the microspheres on which the first and second partially laminated embedded layers are present, the first and second partially laminated embedded layers each occupy an angular arc of at most 180 degrees.

8. The retroreflective article of claim 1, wherein for at least some of the microspheres on which the first and second partially laminated embedded layers are present, the first partially laminated embedded layer occupies an angular arc of less than 40 degrees and the second partially laminated embedded layer occupies an angular arc of greater than 60 degrees.

9. The retroreflective article of claim 1 wherein at least some of the partially laminated inlay layers each include a selective adhesive layer.

10. The retroreflective article of claim 1 wherein at least some of the partially laminated embedded layers each include an embrittled layer.

11. The retroreflective article of claim 1 wherein at least some of the partially laminated embedded layers are reflective layers that each include a metallic reflective layer.

12. The retroreflective article of claim 1 wherein at least some of the partially laminated embedded layers are wavelength selective reflective layers that exhibit a predetermined peak reflection wavelength.

13. The retroreflective article of claim 1, wherein the first partially laminated embedded layers are first reflective layers each comprising a metal reflective layer, and wherein the second partially laminated embedded layers are wavelength selective reflective layers exhibiting a predetermined peak reflective wavelength.

14. The retroreflective article of claim 1, wherein the first partially laminated embedded layer is a first wavelength selective reflection layer exhibiting a first predetermined peak reflection wavelength; and wherein the second partially laminated embedded layer is a second wavelength selective reflection layer exhibiting a second predetermined peak reflection wavelength, and wherein the second predetermined peak reflection wavelength differs from the first predetermined peak reflection wavelength by at least 50 nm.

15. The retroreflective article of claim 1, wherein at least the second partially laminated embedded layer is a reflective layer, and wherein the first partially laminated embedded layer and the second partially laminated embedded reflective layer are configured such that at least at a wavelength between 400 nm and 700 nm, the retroreflective article exhibits a percentage of retroreflection at an incident angle of 30 degrees that is at least 2% greater than the percentage of retroreflection exhibited at an incident angle of 5 degrees.

16. The retroreflective article of claim 1, wherein at least some of the retroreflective elements include an intermediate layer, at least a portion of which is disposed between the transparent microspheres and the binder layer, such that the first partially laminated embedded layer and the second partially laminated embedded layer are disposed behind the intermediate layer and between the intermediate layer and the binder layer.

17. The retroreflective article of claim 1, wherein the binder layer comprises a colorant.

18. A transfer article comprising the retroreflective article of claim 1 and a disposable carrier layer on which the retroreflective article is removably disposed with at least some of the transparent microspheres in contact with the disposable carrier layer.

19. A substrate comprising the retroreflective article of claim 1, wherein the binder layer of the retroreflective article is coupled to the substrate, wherein at least some of the retroreflective elements of the retroreflective article face away from the substrate.

20. An intermediate product, comprising: a disposable carrier layer having a major surface; a plurality of transparent microspheres partially embedded in the disposable carrier layer such that the transparent microspheres exhibit a protruding surface area; wherein at least some of the transparent microspheres each include a first partially laminated release layer present on a portion of the protruding surface region of the transparent microsphere and a second partially laminated release layer present on a portion of the protruding surface region of the transparent microsphere; wherein the first partial laminated isolation layer and the second partial laminated isolation layer are both present as discrete entities; and Wherein, for at least some of the microspheres on which the first partial laminated insulation layer and the second partial laminated insulation layer are present, at least a portion of the second partial laminated insulation layer is arranged parallel to the first partial laminated insulation layer so that incident light can reach the parallel portion of the second partial laminated insulation layer without having to pass through any portion of the first partial laminated insulation layer.

21. A method of making a retroreflective article from the intermediate article of claim 20, the method comprising: disposing a binder precursor on the carrier layer and on the protruding areas of the transparent microspheres carrying the first partially laminated release layer and the second partially laminated release layer; as well as, The binder precursor is cured to form a retroreflective article comprising a binder layer, and wherein the first partially laminated release layer and the second partially laminated release layer are embedded between the transparent microspheres and the binder layer.

22. A method of making an intermediate article comprising a plurality of transparent microspheres, at least some of the plurality of transparent microspheres comprising a first preformed partially laminated barrier layer and a second preformed partially laminated barrier layer, the method comprising the steps of: contacting a region of the first preformed layer with a portion of the protruding regions of at least some of the transparent microspheres carried by and partially embedded in the carrier layer; physically transferring the region of the first preformed layer to the portion of the protruding region of the transparent microsphere that is in contact with the region of the first preformed layer, such that the transferred region of the first preformed layer is bonded to the portion of the protruding region of the transparent microsphere; wherein during the physical transfer process, a physically transferred region of the first prefabricated layer is separated from a region of the first prefabricated layer that previously laterally surrounds the physically transferred region; Then follow these steps: contacting a region of the second preformed layer with a portion of the protruding region carrying at least some of the transparent microspheres of the first partially laminated release layer, the at least some of the transparent microspheres being carried by and partially embedded in the carrier layer; physically transferring the region of the second preformed layer to the portion of the protruding region of the transparent microspheres that is in contact with the region of the second preformed layer such that the transferred region of the second preformed layer adheres to the portion of the protruding region of the transparent microspheres that bears the first partially laminated release layer; wherein during the physical transfer process, a physically transferred region of the second prefabricated layer is separated from a region of the second prefabricated layer that previously laterally surrounds the physically transferred region; wherein the first partial laminated isolation layer and the second partial laminated isolation layer are both present as discrete entities; and Wherein, for at least some of the microspheres on which the first partial laminated insulation layer and the second partial laminated insulation layer are present, at least a portion of the second partial laminated insulation layer is arranged parallel to the first partial laminated insulation layer so that incident light can reach the parallel portion of the second partial laminated insulation layer without having to pass through any portion of the first partial laminated insulation layer.

23. The method of claim 22, wherein the first partially laminated insulating layer and / or the second partially laminated insulating layer is a reflective layer.

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