The use of various types of polymeric sheeting products to mark surfaces such as streets (e.g. cross walk markings and lane stripes) has been known for years. Such sheeting has advantages over painted lines. It has a potentially longer life and more and better ways exist to reflectorize it.
However, a number of problems have hindered the broader acceptance of polymeric sheet pavement markers. One of these problems is that in high traffic areas or in climates which undergo large variations in temperature, sheeting can become loosened from the substrate surface prematurely, i.e. before it is actually worn out.
The actual mode of failure and failure point can vary. The adhesive can fail. The elastic nature of the sheet can create stresses within the sheeting structure that (even after the application of good adhesive and tamping) can cause the sheet to recover its original shape (i.e. its shape before tamping it down onto the road) leaving insufficient contact area for good adhesion to the road. Water and dirt can also lodge between the road and sheet, and, with the action of freezing and thawing and other environmental factors, can further reduce the adhesion of the sheeting to the road.
A sheet which is softer (or more easily conformable) and less elastic is useful in improving adhesion of the sheeting to a substrate. The prior art of inelastically conformable materials includes many materials which lack structural integrity. They conform by being crushed (some plastic foams), by cold flow (waxes and putty), or by other mechanisms which imply lack of strength. Some conformable materials in the prior art are aluminum foil and rubbery polymers of low glass transition temperatures which have not been cross-linked.
Another problem is the actual wear of the sheet by attrition from road dirt and the action of vehicle tires traversing it. Thus, a sheeting which has improved wear properties, ease of conformability, inelasticity, high tensile and tear strength, and low temperature applicability is desired.
USPTO Backgrounds
USPTO Backgrounds