| 摘要 |
827,087. Non-metallic tubes. BOWATER RESEARCH & DEVELOPMENT CO. Ltd. Jan. 16, 1958 [Feb. 5, 1957], No. 3988/57. Class 99(2). In a tube comprising at least one ply of helically wound strip 1 of paper or like material having on one surface a coating 3 of impermeable material such as polyethylene, the longitudinal margins 4 of the strip are folded to overlie the paper surface thereof and thus expose marginal portions 5 of the coating with respect to the paper surface, and there is provided a sealing strip 6 of paper or like material having on one surface a coating 8 of impermeable material superposed on the marginal portions 5, the coatings of the latter and strip being in face-to-face relationship and secured together. As shown, the strip 1 passes through a pair of guides 23, which fold back the margins 4, and over wheels 24 dipping into a bath of cold-setting or thermoplastic adhesive and applying stripes 9 of adhesive to the portions 5, the strip then being wound helically on to a rotatable mandrel 20; the sealing strip 6 is wound helically over the portions 5 and pressed on to the latter by rolls 25. Alternatively, the stripes of adhesive are 'applied by wheels 26 to the strip 6. The heat generated during the winding of the strips is dissipated by internally water-cooling the mandrel and thus preventing the coating of polyethylene on the inside of the tube clinging to the mandrel. An adhesive or priming coat may be used to anchor the polyethylene coating to the paper, and the coatings on the portions 5 and strip 6 may be welded together instead of secured by adhesive. |
