| 摘要 |
1517594 Seaming non-metallic sheet material PRODUITS CHIMIQUES UGINE KUHLMANN 14 April 1976 [16 April 1975] 15317/76 Heading B5K A surface of a polyvinylidene fluoride workpiece is joined to a surface of another polyvinylidene fluoride workpiece by coating at least one of the surfaces with a solvent which will dissolve polyvinylidene fluoride when heated or with a solution obtained by dissolving polyvinylidene fluoride in such a heated solvent, bringing the two surfaces into contact and then heating the contacted surfaces to a temperature above 100‹ C. The solvent used to coat the surfaces or to prepare the polyvinylidene fluoride solution is a polar aprotic solvent or a mixture of such solvents. Specified solvents are dimethylformamide, diemthylacetamide, tetrahydrofuran, dimethylsulphoxide, cyclohexanone hexamethylphosphoramide and butyrolactone. If a solution is used, it may be obtained by dissolving in the solvent 0À1 to 20%, preferably 12-14%, by weight of polyvinylidene fluoride. The solution may be thickened by the addition of an inert filler, e.g. colloidal silica or a montmorillonitic clay. If a solvent is used to coat the surfaces, it may be applied either hot or at ambient temperature. Heating of thecontacted surfaces may be carried out by a hot air torch, a gas torch with flame protector screen, an electric resistance heating strip, a thermofluid or a kiln. Preferably the temperature is in the range 120-170‹ C. The workpieces may be pipes having a wall thickness of at most 10 mm. |
