| 摘要 |
A method of injection molding an opening device (3) on sheet packaging material (2) for packaging pourable food products; the packaging material (2) has at least a first (4) and a second (5, 6) layer, and an opening (9) formed through the first layer (4) and sealed by a cover portion (10) of the second layer (5, 6); the method includes the steps of injecting molten plastic material onto a first side (10a) of the cover portion (10) of the second layer (5, 6), feeding the molten plastic material along the cover portion (10) to cover it on the first side (10a), and feeding the molten plastic material through an annular peripheral portion of the cover portion (10) to form a spout (12) of the opening device (3) projecting from a second side (10b), opposite the first side (10a), of the cover portion (10); the molten plastic material covers the cover portion (10) to define, with the cover portion (10), a user-removable sealing portion (15) of the spout (12). |
