| 摘要 |
<p>A retroreflective material is produced from a multiplicity of thermoplastic or thermosetting granules (20) in the shape of tetrahedrons. A plurality of glass spheres (27) having a diameter in the range of from 6.0 microns to 3175 microns (0.125 inches) are substantially evenly dispersed throughout each granule (20) with some of the spheres protruding through the outer granule surfaces. The proportion of spheres to granule material being from 30-60% by weights. The glass spheres (27), the granule material and a suitable pigment are mixed together and then applied to a flexible sheet (35) or a roller (40,41) containing a multiplicity of tetrahedron-shaped indentations (42). The mixture is urged into each of the indentations (42) and is then cured. The resulting granules (20a, 20b, 20c) are dropped randomly onto a freshly painted highway line or other surface e.g. sign such that one of the flat faces on each granule is disposed in a downward direction. <IMAGE></p> |
