| 摘要 |
1505198 Embossing J L GANTZER 15 April 1976 [17 April 1975] 15690/76 Heading B6J [Also in Division B5] A plastics web, for thermoforming into receptacles for alimentary products, has one or both major surfaces 2 comprising alternate grooves 3 and ribs 4 extending along its length, the base of each groove 3 being provided with indentations 5 spaced apart along its length. The web is made by extrusion from a die outlet which defines the configuration of the grooves and ribs 3, 4, and impressing the indentations in the web at the exit of the die, by means of a roller bearing ribs and grooves matching those of the web, and projections from its ribs for impressing the indentations. The impressing may cause elongation of the web. The grooves 3 and 4 may be rectangular, or saw toothed, Fig. 4 (not shown), or may be of different configuration across the width of the web to ensure a constant thickness upon thermoforming. The indentations may be hemispherical, trapezoidal, octagonal or cubic. The surface 2 may be rendered planar, by simultaneously extruding a film thereon, or a pair of webs may be simultaneously extruded with surface 2 facing each other and laminated to a film providing barrier resistance to ultraviolet radiation for manufacturing long life packages. The shaping profile of the die and roller may be obtained by engraving, or electro erosion, and the roller may comprise a coating of antiadherent material.
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