Adhesive composite materials, uses thereof, and preparation method thereof

Abstract

J&W Ref: 327015 Abstract The invention relates to adhesive composite materials and, more particularly, to conformable, reversible- adhesion composites for temporary signage suitable for use on existing road signs and other smooth or near-smooth substrates. Abstract near-smooth substrates. J&W Ref: 327015 20 26 20 26 82 09 A pr 2 02 6 2 0 2 6 2 0 2 6 8 2 0 9 A p r 2 0 2 6 A b s t r a c t n e a r - s m o o t h s u b s t r a t e s . J & W R e f : 3 2 7 0 1 5 2 0 2 6 2 0 2 6 8 2 0 9 A p r 2 0 2 6 A b s t r a c t n e a r - s m o o t h s u b s t r a t e s . J & W R e f : 3 2 7 0 1 5 J&W Ref: 327015 Figure 1 2 4 IN 4 NI 80 Fair ROIRD CREEK TEMPORARYEN DI 20 26 20 26 82 09 A pr 2 02 6 A p r 2 0 2 6 2 0 2 6 2 0 2 6 8 2 0 9 4 8 0 J & W R e f : 3 2 7 0 1 5 2 0 2 6 2 0 2 6 8 2 0 9 2 0 2 6 A p r 4 8 0 J & W R e f : 3 2 7 0 1 5

Description

1. FIELD OF THE INVENTION 5 The present invention relates to the field of adhesive composite materials, and more specifically to adhesive composite materials designed for reversible application to a surface. The invention further relates to uses of adhesive composite materials and methods for preparing adhesive composite materials. 2. BACKGROUND TO THE INVENTION Signage is ubiquitous, and a critical means for conveying accurate information at a specific location. However, most signage is static - meaning that unless the information conveyed in that signage remains constantly relevant, then the signage needs to be removed and replaced with new signage conveying the 15 changed information. Previous solutions to this well understood problem of conveying changed information at a location include the use of technology to provide dynamic signage, which can often be adapted to the prevailing conditions either at the location of the signage or even remotely. Such signage, however, is typically 20 significantly more expensive than static signage and typically requires a source of power to operate. Road signage is widespread and generally needs to be cheap and so dynamic signage is typically not a reasonable solution in the majority of applications. Also, road signage is often remote from a source of power unless local power supplies such as solar panels are used which themselves can be subject to 25 vandalism and add cost. That said, in most cases, static road signage provides its function perfectly well -displaying such information as speed limits, road design, and impending hazards. Nonetheless, there are times when static road signage does not provide its function well, including when there are changes to speed limits, road design, and impending hazards. Sometimes those changes are 30 only temporary, and the nature of the speed limits, road design, and impending hazards will revert in due course. In such cases, permanent replacement of the whole sign may not be desired or appropriate. To date, one of the main approaches to temporary road signage solutions is to physically cover the in situ static road signage and introduce a portable signage solution to the location to show the changed 2026202682   09 Apr 2026 conditions. Such portable signage solutions typically must be engineered to be resilient enough to independently withstand the wind, rain, and other environmental conditions found in the location. In many cases that involves the use of a stable metal frame or stand to which the new signage is mounted. Often, such a metal frame or stand will need to be supplemented with sand bags. Because of the need for 5 the metal frame or stand to be durable, such signage generally needs to be substantial and is usually deployed by a specialist vehicle tasked with installing and removing temporary signage. Even then, a suitable location must be found for the portable signage which can be difficult in dense urban environments and such signs are exposed to being knocked over either accidentally or intentionally. Meanwhile the in situ static road signage is generally covered with a hessian or plastic bag, retained in place by tape or cord. In many instances this covering performs poorly in harsh weather conditions. In some instances more durable canvas-like coverings can be used, but again, those solutions merely cover the static signage without providing the road user with the new information. 15 There is a need for a temporary road signage solution that ameliorates or avoids one or more of the above problems, which include the complexities and cost of dynamic signage, and / or the use of separate metal frames or stands. Alternatively there is a need for a useful choice in signage, such as road signage. 3. DESCRIPTION OF THE INVENTION 20 The present invention is predicated in part on the discovery of an adhesive, flexible composite material that can be used to provide temporary, reversible adhesion to a smooth surface without the use of chemical adhesives, or mechanical fasteners. Advantageously, in addition to an adhesive layer, the adhesive composite material may include a layer of material capable of conveying signage information, 25 particularly road signage information. In some cases the composite material provides a layer of reflective material which is well-suited for use in road signage applications. The adhesive layer is typically provided as a nano- or micro-structured three-dimensional layer. Without wishing to be bound by theory, it is believed that the nano- or micro-structured three-dimensional 30 adhesive layer provides the composite material with exceptional adhesion to a wide-variety of substrates (such as metal, glass, plastic, and painted substrates), while retaining the flexibility of the material and the ability to manually remove the composite material from a substrate when appropriate. Preferably the material can be removed without tools. The membrane demonstrates effective adhesion to not only 2026202682   09 Apr 2026 smooth surfaces but also to non-smooth surfaces and those partially contaminated with detritus, exhibiting a high degree of tolerance to surface irregularities. In a first aspect, the invention provides an adhesive, flexible composite material including (i) a nano- or 5 micro- structured adhesive layer; and (ii) a signage layer and / or a reflective layer. Typically the adhesive layer will be formed from a polyurethane. Typically, for road signage applications, the composite material will include both a signage layer and a 0 reflective layer. The reflective layer may be formed from a high-intensity reflective sheeting, such as engineer grade or diamond grade. Engineer grade reflective material is a retroreflective sheeting designed for non-critical traffic signs, commercial signage, and other applications requiring enhanced visibility in low-light 15 conditions. Such material may contain glass beads or microprismatic optics. Such reflective sheeting may be appropriately coloured, such as to match the road signage to which it is being applied. Examples of suitable colours are white, orange, yellow, red. The signage layer may be formed from a vinyl which conveniently may have signage on it. Such signage 20 may be drawn and / or printed on the vinyl using a range of conventional techniques. Examples of suitable signage include numerical values (such as speed limit values), symbols (such as road work, slippery conditions, snow or ice), and other abstract shapes such as lines, crosses, circles. While it is convenient to describe the composite material of the invention in relation to its use in road 25 signage applications, the composite material may be used in any number of other signage applications. Without wishing to be bound by theory it is believed that the flexible nature of the adhesive composite material provides the material with significant versatility. For instance, while road signage is typically manufactured in a planar manner, it is not uncommon for in situ road signage to become non-planar due 30 to damage from falling tree limbs, or incidental collisions with vehicles. The flexibility of the adhesive composite material of the present invention provides the user with greater versatility. Moreover, the flexible nature of the adhesive composite material enhances the material’s application to: commercial branding; law enforcement (such as when applied to curved car body panels and windows; such as for use in temporary crash signage); event signage; real estate signage; construction and rail safety; and custom 35 emergency responses. 2026202682   09 Apr 2026 In some embodiments the nano- or micro-structures adhesive layer is formed from a multitude of nano-or micro-structured elements such as suction elements. Such suction elements, at a resting stage when not adhered to a substrate, are typically concave or hemispherical in shape. Where formed from a 5 deformably resilient material, such as a polyurethane resin, the suction elements can deform under pressure applied against a substrate, to form sealed cavities between the adhesive layer and the target substrate. As the deformably resilient material resiles to its undeformed shape, such as due to molecular restorative forces present in a deformed elastomeric material, each deformed suction element attempts to revert to its pre-deformed shape. The competing forces of the resilient material trying to return to its 0 undeformed shape versus the negative pressure created within the suction element adhered to the substrate are in equilibrium, resulting in a secure, non-chemical bond to the substrate which resists the action of most disruptive forces in use, such as wind, rain, and / or temperature fluctuations. In turn, the adhered composite material remains in place until it is not needed. 15 Advantageously, these adhesive, flexible composite materials also exhibit releasability when subject to greater force than typically provided by wind, rain and temperature fluctuations. By manually disrupting the equilibrium, the composite material can be cleanly detached without leaving residue or causing damage to the target substrate. These mechanisms of adhesion and release allow the composite material to be reused multiple times, making it a sustainable alternative to conventional adhesive-backed 20 materials. Preferably the composite material can be removed from the substrate without tools. Furthermore, the nano- or micro- structured adhesive layer allows the composite material to be adhesive when applied in a non-planar form, such as around a curved object. Without wishing to be bound by theory it is believed that the difference in scale between the curvature of a target substrate and the nano- 25 or micro-scale of the adhesive elements, permits this versatility. Advantageously the adhesive, flexible composite material may be provided in a range of shapes, sizes, and thicknesses and may be transported easily to be applied in a wide range of signage applications. 30 The adhesive, flexible composite material of the invention may be applied to a range of substrates including vehicles, exiting road signs, barriers, bus sides, concrete walls, or any relatively smooth surface where temporary signage is desired. 2026202682   09 Apr 2026 The reflective material maintains optical performance under variable lighting conditions, including lowlight and night-time. The composite is also resistant environmental degradation, including exposure to UV radiation, moisture, and temperature fluctuations. 5 The nano- or micro- structured suction layer may be configured to adhere to a target surface by suction. The reflective layer for enhancing visibility under low-light conditions may be disposed on the suction layer. The reflective layer for enhancing visibility under low-light conditions may be proximal to the suction layer. The layers may be arranged so that the suction layer contacts with the target surface, while the reflective layer is visible. The configuration allows the adhesive membrane to be adhered securely to a 0 surface whilst serving as a visual indicator. Optionally, the membrane further includes (iii) a graphic layer. The optional graphic layer may be a vinyl film. The graphic layer may display custom graphics, symbols, or text, depending on the intended application. The graphic layer may be disposed on the reflective layer. The configuration of the layers may be such that the reflective layer is sandwiched between the nano- or micro- structured suction layer and an opposing graphic layer. The graphic layer may be distal to the 15 nano- or micro- structured suction layer. The membrane may be conformable to both flat and / or curved surfaces. In a second aspect, the invention provides a reusable temporary road sign cover, said covering comprising an adhesive, flexible composite material according to the first aspect of the invention. 20 In a third aspect, the invention provides an adhesive, flexible composite material produced by a process comprising: (i)      mixing a polyol with a diisocyanate and / or polyisocyanate to form a polyurethane precursor; 25 30 (ii)     transferring the polyurethane precursor into a mold configured to provide a plurality of nano- and / or micro- structured elements; (iii)     allowing the polyurethane precursor to cure within the mold to form an adhesive layer having a first face comprising a multitude of nano- and / or micro- structured elements and a substantially planar second face opposite the first face; (iv)     removing the cured polyurethane adhesive layer from the mold; and (v)      adhering a reflective layer and / or a signage layer to the second face of the cured polyurethane adhesive layer to provide the adhesive, flexible composite material. 2026202682   09 Apr 2026 The polyol may be a compound having a plurality of hydroxyl groups. Such a polyol may be a polyether polyol and / or 1,2-propylene glycol. Polyether polyols may be present in the polyurethane precursor at more than 60% w / w, such as more than 70% w / w, such as more than 75% w / w. Polyether polyols may be present in the polyurethane precursor at less than 90% w / w, such as less than 80% w / w. Polyether polyols 5 may be present in the polyurethane precursor at about 76% w / w. 1,2-propylene glycol may be present in the polyurethane precursor at less than 5% w / w, such as less than 2.5% w / w. 1,2-propylene glycol may be present in the polyurethane precursor at more than 0.5% w / w, such as more than 1.0% w / w. 1,2-propylene glycol may be present in the polyurethane precursor at about 0   1.5% w / w. The diisocyanate and / or polyisocyanate may be present in the polyurethane precursor at more than 10% w / w, such as more than 15% w / w, such as more than 20% w / w. The diisocyanate and / or polyisocyanate may be present in the polyurethane precursor at less than 40% w / w, such as less than 30% w / w, such as 15 less than 25% w / w. The diisocyanate and / or polyisocyanate may be present in the polyurethane precursor at about 22.5% w / w. In a fourth aspect, the invention provides a method of using an adhesive, flexible composite material as temporary road signage, the method comprising the steps of: 20            (i)      aligning the adhesive, flexible composite material with information provided on a road sign substrate; and (ii)      applying the adhesive, flexible composite material so that the adhesive, flexible composite material substantially covers at least part of the information on the road sign substrate. 25 Optionally, the method may further include the step of removing the adhesive membrane by peeling it away from the target surface, such as when the temporary signage condition no longer applies. The adhesive, flexible composite material used in the method of the fourth aspect may be the adhesive, flexible composite material of the first aspect or the adhesive, flexible composite material produced by the 30 method of the third aspect. In a fifth aspect the invention provides the use of an adhesive, flexible composite material as temporary road signage when adhered to a road sign substrate. 2026202682   09 Apr 2026 The adhesive, flexible composite material used in the fifth aspect may be the adhesive, flexible composite material of the first aspect or the adhesive, flexible composite material produced by the method of the third aspect. 5 4. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the technology will be described below by way of example only, and without intending to be limiting, with reference to the following drawings, in which: Figure 1 shows one application of the adhesive, flexible composite material of the invention (2) to a temporary road sign (4). In this example, while road works were being conducted in the area a temporary speed limit sign of 40 km / h was installed. Outside of the times when the road working crew was operating, the speed limit could be changed to 80 km / h using the signage of the present invention to 15 enable more normal movement of traffic in the area. When the road working crew was set to begin work again, the signage of the present invention could be removed, to reveal the temporary speed limit of 40 km / h again. Figure 2 shows an example of the shape and dimensions of a composite material of the invention. 20 For clarity, the term nano- or micro-structured encompasses structures whose characteristic dimensions are, respectively, below about one micrometre (nano-scale) and in the micrometre to sub-millimetre scale (micro-scale). 25 In one example a polyurethane-based nano- or micro- structured adhesive layer may be provided by curing a polyurethane precursor in a mold configured to provide a plurality of suction elements on a first face, removing the cured layer from the mold, and adhering a reflective layer and / or a signage layer to the opposite face to form the adhesive, flexible composite material. The polyurethane precursor may comprise a polyether polyol (for example in the range above 60% w / w and below 90% w / w), 1,2 30 propylene glycol (for example above 0.5% w / w and below 5% w / w), and a diisocyanate and / or polyisocyanate (for example above 10% w / w and below 40% w / w). 2026202682   09 Apr 2026 Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of “including, but not limited to”. 5 Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world. 0 The technology may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features. Where in the foregoing description reference has been made to integers or components having known 15 equivalents thereof, those integers are herein incorporated as if individually set forth. It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the technology and without diminishing its 20 attendant advantages. It is therefore intended that such changes and modifications be included within the present technology.

Claims

1. An adhesive, flexible composite material including (i) a nano- or micro- structured adhesive layer;and (ii) a signage layer and / or a reflective layer.

2. The adhesive, flexible composite material according to claim 1 including a signage layer and areflective layer.

3. The adhesive, flexible composite material according to claim 1 or claim 2, including a reflectivelayer interposed between the nano- or micro- structured adhesive layer and a signage layer.

4. The adhesive, flexible composite material according to any one of claims 1 to 3 wherein the nano-or micro- structured adhesive layer is formed substantially of a polyurethane polymer.

5. The adhesive, flexible composite material according to any one of claims 1 to 4 wherein thesignage layer is formed substantially of a vinyl polymer.

6. The adhesive, flexible composite material according to any one of claims 1 to 4 wherein thereflective layer is formed substantially of an engineer grade or diamond grade material.

7. A reusable temporary road sign cover, said covering comprising an adhesive, flexible compositematerial according to any one of claims 1 to 6.

8. An adhesive, flexible composite material produced by a process comprising:(i)      mixing a polyol with a diisocyanate and / or polyisocyanate to form a polyurethaneprecursor;(ii)     transferring the polyurethane precursor into a mold configured to provide a plurality ofnano- and / or micro- structured elements;(iii)     allowing the polyurethane precursor to cure within the mold to form an adhesive layerhaving a first face comprising a multitude of nano- and / or micro- structured elements and a substantially planar second face opposite the first face;(iv)     removing the cured polyurethane adhesive layer from the mold; andadhering a reflective layer and / or a signage layer to the second face of the cured polyurethane adhesive layer to provide the adhesive, flexible composite material.102026202682   09 Apr 20269.      The adhesive, flexible composite material according to claim 8 including both a reflective layerand a signage layer.

10. The adhesive, flexible composite material according to claim 8 or claim 9 wherein thepolyurethane precursor includes more than 60% w / w and less than 90% w / w of a polyether polyol.

11. The adhesive, flexible composite material according to claim 8 or claim 9 wherein thepolyurethane precursor includes more than 10% w / w and less than 40% w / w of a diisocyanate and / or polyisocyanate.

12. A method of using an adhesive, flexible composite material as temporary road signage, themethod comprising the steps of:(i)      aligning the adhesive, flexible composite material with information provided on a roadsign substrate; and(ii)     applying the adhesive, flexible composite material so that the adhesive, flexiblecomposite material substantially covers at least part of the information on the road sign substrate.

13. The method according to claim 12 wherein the adhesive, flexible composite material is as definedin any one of claims 1 to 6.

14. Use of an adhesive, flexible composite material as temporary road signage when adhered to aroad sign substrate.

15. Use according to claim 14 wherein the adhesive, flexible composite material is as defined in anyone of claims 1 to 6.

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