| 摘要 |
Backup material for drilling consisting of a laminate which is substantially made up of a layer of fluted paper (12) and facings (11, 14), i.e. corrugated board, for instance single faced or single wall corrugated board, of which layers at least the facing or facings are impregnated with a resinous composition, such as phenolic resin, which is cured after the impregnation. |
