| 摘要 |
A triple core (6,4,5), includes an impermeable inner barrier (4). The outer layers (6,5) are heat activated adhesive sheets. Their (6,5) viscosity, or plasticity, over a given, limited temp. range (TA, TB), is very different from that of the barrier (4). They (5,6) may be thermoplastic; their m.pt. is at least 20 deg C, pref. 30 deg C, below that of the barrier layer (4). Two outer layers (2, 3) sandwich the core. At least one of these (2, 3) is fibrous and fluid absorbent; it is pref. wood flour or ground pulp. The triple layer (4, 5, 6) consists of copolymer sheets with differing fusibilities. The composite resists distortion, and is esp. useful as a shell for packing items which can release fluids.
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