Paperlike sheet materials.

摘要

A thermally formable paperlike sheet material comprising at least 25% synthetic thermoplastics material a substantial proportion of which is fibrillated, with at least a substantial portion of the balance 100% being of cellulosic fibres, said sheet having a thickness of less than 140 microns and being treated to exhibit a minimum tensile strength along a first axis of 12 Newtons, and along a second axis at right angles to the first axis of 8 Newtons, per 25 millimetres of width transverse to the respective axis, and a permeability to air of less than 100,000 cubic centimetres per minute through an area of 10 square centimetres and at a pressure of 10 centimetres water gauge. Such sheet material finds particular application for use as wrappers or in forming sealed closures (4) for containers (2) having convoluted surfaces (3) and which hold materials (1) like freshly ground coffee which are required to breathe (7) without being exposed to ambient conditions.