Process for manufacturing a flat-bottom bag and bag formed thereby

A process for manufacturing a flat bottom bag, said process comprising the steps of:

• I. providing a bag preform and a patch,
• said patch having a first adhesive coating thereon,
• said preform being formed from an elongate tube of bag-forming material, said tube comprising an inner tubular liner of bag-lining material sheathed by an outer tubular shell of bag-facing material and having a peripheral baseline which divides said tube into a tubular wall-forming part including a preform upper end and a tubular bottom forming part including a preform lower end,
• said bottom-forming part having four division lines, running lengthwise, along the length of the tube, and dividing said bottom-forming part into four substantially rectangular bottom-forming portions including a pair of substantially congruent flap-forming panels and a pair of substantially congruent gusset panels, disposed in alternating relation,
• wherein one of the flap-forming panels has a staggered slit arrangement including
• a pair of relatively long first slits formed through the shell, extending from the preform lower end, lengthwise, to respective termini and arranged such that each of the division lines which bracket said flap-forming panel has a respective one of the first slits disposed relatively proximal thereto;
• and
• a pair of relatively short second slits formed through the liner, extending from the preform lower end, lengthwise, to respective termini, and arranged such that each of the division lines which bracket said flap-forming panel has a respective one of the second slits disposed relatively distal thereto;
• and wherein each flap-forming panel has a pair of flap-forming creases associated one each with the division lines which bracket said each flap-forming panel and each extending in angular relation to its associated division line and from the intersection thereof with the peripheral baseline to,
• with respect to the other one of the flap-forming panels, the preform or end, so as to divide said flap-forming panel into a quadrilateral flap and a pair of opposed triangular gussets;
• and
• with respect to said one of said flap-forming panels, the terminus of a respective first slit, in the case of the shell, and the terminus of a respective second slit, in the case of the liner, so as to divid said flap-forming panel into a ridged flap and a pair of opposed polygonal gussets,
• said preform being provided in an open configuration
• whereat the triangular gussets and the polygonal gussets are folded inwardly along the flap-forming creases contiguous therewith such that the division lines are arranged substantially coincident with the peripheral baseline, thereby to form, with the quadrilateral flap and the ridged flap, respectively, primary and secondary flaps
• and whereat the primary and secondary flaps extend substantially away from one another, such that the triangular gussets and the polygonal gussets form substantially smooth continuous surfaces with the gusset panels to which they are respectively attached;
• ii. positioning the patch at a sealing position against said smooth continuous surfaces, with the first adhesive coating disposed therebetween, to form a preform/patch composite;
• iii. folding the primary flap about the peripheral baseline to a closure position thereof whereat same lies in substantially stacked relation relative to the gusset panels;
• folding the secondary flap about the peripheral baseline to a closure position thereof whereat same lies in substantially stacked relation against the primary flap;
• and
• providing means for securing the primary flap and the secondary flap at their respective closure positions.