Method of making a retroreflective article and a retroreflective article having an aluminum reflector

Retroreflective articles have the ability to return substantial quantities of incident light, which otherwise would be reflected elsewhere, back towards the light source. This unique ability has led to widespread use of retroreflective articles in a variety of applications relating to traffic and personal safety. For example, in the personal safety area, retroreflective articles have been used on clothing, primarily to enhance a pedestrian's visibility to motor vehicle operators after dusk or under other low visibility conditions. They also have been attached to book-bags and backpacks for the same purpose. Retroreflective articles can be made from cube-corner structures, such as cube-corner elements and cube-corner shaped cavities. A process for making a retroreflective article that includes the steps of providing a device (tool or a mold) having a first structured surface; applying a reflective layer on the first structured surface resulting in a first adhesion value between the reflective layer and the first structured surface, the reflective layer having an exposed surface; applying a molding polymer to the exposed surface of the reflective layer resulting in a second adhesion value between the reflective layer and the molding polymer. The second adhesion value is higher than the first adhesion value. The device is separated from the molding polymer to yield a retroreflective article that has a second structured surface that is the reverse image of the first structured surface. The separation causes a transfer of the reflective layer from the first structured surface to the retroreflective article. The method allows the reflective layer to be formed during the separation step, rather than being formed independent of creating the second structured surface. The method can yield a article that has a second structured surface coated with an aluminum reflective material having aluminum microstructures that are predominantly amorphous on a first side (the side near the second structured surface) and predominantly crystalline on a second side, which is opposite the first side.