| 摘要 |
An article is formed of sheet material which includes a relatively rigid cellular layer 10 sandwiched between two relatively flexible layers 11 and 12. All three layers are of h.f. weldable plastics, and the article is formed by a continuous seam line 13 within the boundary of the sheet material, the material outside the seam line being discarded. Production speed is increased because the sheet material no longer needs to be accurately positioned. The cellular layer may be in the form of a layer having indentations as shown in Figure 3 or a corrugated layer or as shown in Figure 5. The article may be a ring binder, slip case or a coaster. <IMAGE> |
