| 摘要 |
<p>903,948. Ornamenting. MINNESOTA MINING & MANUFACTURING CO. Sept. 17, 1958 [Sept. 18, 1957], No. 29783/58. Class 93. [Also in Group XX] A reflex reflecting element comprising a rigid core 10 to which is bonded at 11 glass beads 12, may be formed by adding to crushed greystone rock a bond solution consisting of epoxy resin and polyamide resin dissolved in toluene. The epoxy resin may be produced by the reaction of 2,2-bis-(4-hydroxyphenol) propane and epichloryhydrin in alkaline media at temperatures of 50-150‹ C. Other polyhydric phenols which may be used are resorcinol or 2,2-bis-(4-hydroxyphenol)-butane. To the tacky granules in the mixer are added silvercoated glass beads, and the batch from the mixer is then poured on to a 40-mesh screen which is vibrated to remove excess beads. The batch is then aged at room temperature for 48 hours, and finally etched to remove the silver coating from the outer surfaces of the beads. In place of the epoxy -resin bond, a polyurethane resin bond may be used.</p> |
