GB1013783A - Improvements in or relating to tear tapes for plastic films - Google Patents

Abstract

1,013,783. Packaging. B. X. PLASTICS Ltd. Dec. 8, 1961 [May 25, 1961], No. 19012/61. Heading B8C. [Also in Division B5] Films, for example of polythene, polyethylene terephthalate or oriented polypropylene, used for packaging are provided with a tear strip or strips of relatively inextensible material such as regenerated cellulose or polyvinyl resin, or of the same material as the film where these are inextensible. The strip or strips may be secured by pressuresensitive adhesive, or by a cold-setting adhesive which must also be coated on the area of the film to which the strip or strips is/are to be attached. The strip may be duplicated, one strip acting as an abutment for the other during tearing, or may be provided as, or slit into, three strips which may be applied side by side or two on one side of the film and the third, the centre one, on the opposite side. The film may be weakened on either side of the strips, as by scoring with a knife edge or a roller carrying projecting peripheral wires, or by abrading with a rotating wire brush. If the film is oriented the strips may be secured at an angle to the direction of orientation. The strips may be coloured or laminated, one layer carrying advertising or other marking. In Fig. 11 a web 11 of polythene is fed from a roll 12 by rollers 13 and has applied to it a pair of strips coated by means, not shown, with cold-setting adhesive and formed by slitting a web 15 by a pair of knives 17 and reeling up the centre strip 18 of the three so formed. A corresponding centre strip 19 from a previous operation is applied to the underside of the web 11 in a position between the two upper webs, the whole being pressed together by rollers 14, or by a single roller co-operating with a spring-pressed roller the width of the tapes. To facilitate tearing, in a case for example where three parallel strips 3, 4, 5, Fig. 14, are provided, the edge of the film 24 is slit for a short distance on each side of the centre strip 4 and the adjacent areas 25, 26 are heat-sealed to other overlapped portions of the film. Alternatively, portions of the film 24 on both sides of the strip 4, and including corresponding parts of the strips 3, 5, are cut away, other parts of the film being overlapped and heat-sealed to close the gap so formed.