| 摘要 |
962,497. Producing thin filter paper. L. V. GEWISS. June 8, 1962 [June 12, 1961], No. 22292/62. Headings D1L and D2B. Thin sheets of fibrous filter material are produced by impregnating sheets of normal thickness with a solution of a suitable synthetic resin, heating the sheet to cause the solvent to evaporate and to cause the resin to migrate to and become concentrated at the faces of the sheet where it acts to bind the fibres together at their points of contact and subsequently splitting the sheet along its thickness to provide two sheets each of half the original thickness. Filter material of normal thickness is unwound from a roll 2 and is fed by means of rollers 3, 4 and 6, 7 through an impregnation vessel 5 containing a solution of e. g. ureaformaldehyde in alcohol. The sheet is dried in a drying oven 9 comprising a series of vertical compartments 9a....... 9f through which the filter sheet passes in zig-zag fashion being guided by rollers 10a..... 10h, emerging finally in vertically downward movement from a horizontal compartment 9g. Hot air is circulated through the oven in the reverse direction by a fan 15. From the oven 9 the sheet is led between opposed rollers 11, 12 and is split upon emerging from the rollers and is would at constant linear velocity on to drums 13, 14. Initial splitting of the impregnated dried sheet is effected by hand. The splitting operation leaves one side of each filter sheet particularly hairy but this surface may be smoothed by a grinding operation (Fig. 2 not shown). |
