| 摘要 |
<p>1,259,303. Etching. GENERAL ELECTRIC CO. 23 Jan., 1969 [1 Feb., 1968], No. 4019/69. Heading B6J. A body, such as a sheet, of etchable copolymer comprising etchable polymer and non-etchable polymer is bombarded on its surface with charged particles to produce straight tracks of damaged copolymer, an etchant then being applied to remove material along the tracks and produce recesses or apertures in the body. Etchable polymers are polycarbonates, polyethylene terephthalate, crystalline polyethylene, polystyrene and cellulose esters. Unetchable polymers are polytetrafluorethylene and elastomers. The etchant is hydrofluoric acid, sodium or potassium hydroxide, or potassium permanganate. The particles may be argon or oxygen ions or alpha particles, or fission fragments of uranium 235 or californium 252. The particle packs and thus the tracks may be made parallel by interposing a solid apertured sheet. The sheet may be bombarded while stretched, and then etched while still stretched or after being released. The unetchable polymer forms from 1-90% of the copolymer. The recesses or apertures are cylindrical, frusto-conical or of hour-glass shape, and can be widened, or recesses converted into apertures, by further etching. The product can be used to form porous contact lenses or filters, such as molecular sieves. The recesses and apertures can be filled with material other than the surrounding copolymer, for example iron particles to form a ferromagnetic sheet.</p> |
