Conformable cube corner retroreflective sheeting

Abstract

Conformable cube corner retroreflective sheetings comprising a plurality of discrete cube corner segments which are conformably bonded together, each cube corner segment comprising a plastic body portion having a substantially planar front major surface and at least one minute cube corner retroreflective element projecting rearwardly from the body portion and defining a cube corner point side of the cube corner segment. The peripheries of the cube corner segments can be defined by a plurality of separations extending from the cube corner point sides to the front major surfaces, the separations being disposed between adjacent cube corner segments. Adjacent cube corner segments are conformably bonded together in the sense that they are either: (1) separated by a gap of less than about 1 millimeter and bonded together through a conformable carrier layer; or (2) separated by a gap which is substantially filled with a conformable resin that bonds the side walls of adjacent cube corner segments together. Alternatively, a conformable cube corner retroreflective sheeting can comprise a plurality of connecting bridges disposed between adjacent cube corner segments, the connecting bridges being at least one of fractured and frangible, and spanning grooves which extend vertically from the cube corner point sides toward the front major surfaces and terminate at the connecting bridges. Also, methods for making such conformable sheetings.

Description

[0001] The present invention relates to retroreflective articles, particularly cube corner type retroreflective articles.[0002] Retroreflective articles are made in a variety of forms, including sheetings such as are used on traffic signs and license plates, rigid safety reflectors mounted on motor vehicles and bikes, and patches and appliques such as are applied to garments and book bags, etc. One major use of retroreflective sheeting is in the field of highway markings and signs to improve the visibility and legibility of informational signs, traffic directions, barriers, etc. to drivers.[0003] One common type of retroreflector employs transparent microspheres, typically with hemispheric reflectors thereon. Illustrative examples of such retroreflectors are disclosed in U.S. Pat. No. 3,190,178 (McKenzie), U.S. Pat. No. 4,025,159 (McGrath), and U.S. Pat. No. 5,066,098 (Kult).[0004] A second common type of retroreflector employs what are referred to as cube corner retroreflective ele...

AI Technical Summary

Benefits of technology

[0039] Further, the method can comprise the steps of substantially filling the separations with a conformable resin so that the conformable resin contacts the side walls of adjacent cube corner segments, and effecting substantial solidification of the conformable resin so that it conformably bonds the cube corner segments together. If desired, the conformable carrier layer and conformable resin can be stretched to increase the width of the separations (i.e., to increase the gap between adjacent cube corner segments).

Problems solved by technology

In U.S. Pat. No. 3,992,080 (Rowland), it is noted that the cube corner elements of the retroreflective composite material disclosed in U.S. Pat. No. 3,684,348 are distorted when the material is stretched during application to a support surface, and such distortion renders the cube corner faces non-orthogonal to a degree, resulting in significant loss of brightness.

However, it is believed that the sheet assembly is not particularly useful when mounted to non-planar substrates which have intricate shapes or very small dimensions such as truck trailer rivets and corrugations because of the shear size of the gaps and film pieces in the sheet assembly.

The gaps present areas of the sheet assembly which are not capable of retroreflecting light.

In other words, the gaps can likely be made only so small before bonding of the base and cover sheets in the bonding areas is not possible.

In addition, the patent discloses that the base and cover sheets are flexible to provide for flexible constructions, but does not disclose conformable base and cover sheets to provide for conformable constructions.

Lastly, the sheet assembly is typically difficult to manufacture because the retroreflective film pieces must generally be cut and arranged in stacks in the manufacturing process.

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