GB1256957A - - Google Patents

Abstract

1,256,957. Block-bottomed bag. CRAFSAC. 14 March, 1969 [15 March, 1968; 4 Feb., 1969], No. 13549/69. Heading B8K. A block-bottomed bag is formed by inserting a tube of plastics material into at least one tube of paper ply, flattening the tubes and applying a transverse stripe of anti-adhesive material to the edge of the inner surface of the or the inner paper ply along one flattened half only, welding along the line of anti-adhesive so that the plastics lining is joined to the other flattened half of the inner paper ply, and then folding and adhesively sealing the end of the bag. The paper plies 2-4 and lining member 6 may be longitudinally staggered and this, together with the degree of overlap on folding the bag end, may be varied as follows:-(a) lining 6 and ply 2 level, but staggered with respect to plies 3 and 4 (Fig. 5), with the transverse edges of ply 2 overlapped on folding, (b) ply 3 staggered with respect to ply 4 (Fig. 1, not reproduced), and the transverse edges of ply 2 meeting on folding, (c) plies 2, 3, 4 level, but staggered with respect to lining 6 (Fig. 8, not reproduced) and the transverse edges of all paper plies overlapped on folding. The lining member may be provided with bellowed edges (see Fig. 1). The bag end is folded diamond-wise in conventional manner and sealed with one or more adhesive papers 13. Welding may be performed by direct heating, dielectric heating or ultrasonic fusion. Conventional tube- and bag-forming apparatus may be used, and longitudinal staggering of the plies produced by the breaking of transverse weakening lines along a series of continuous tubes, with welding by means of electrodes. Both bag ends may be similarly sealed, with a filling valve at one end.