FORMATION OF SQUARE BOTTOM OF MULTIWALL KRAFT PAPER SACK WITH SYNTHETIC RESIN FILM INTERPOSED IN BETWEEN IN CONTINUOUS SACK MAKING

摘要

PURPOSE: To enable sheets of kraft paper to be stuck together with one another, especially in forming a bottom for a sack, for making adherence film by a method wherein a synthetic resin film partly exposed during the process of sack making is heated and shrunk with a heater or the like, and thereby the synthetic resin film is kept from being exposed to the surface whereon adhesive agent is applied. ;CONSTITUTION: In manufacturing a kraft paper sack by providing an intermediate sheet of kraft paper 4 provided with a polyethylene film 3 between an inner sheet of kraft paper 1 and an outer sheet of kraft paper 2 which is made slightly shorter than the inner sheet, a U-shaped indent 5 for exposure is formed on the front end of the inner kraft paper 1 and an extension 6 is formed on the front end of the outer kraft paper 2. A sheet of spread paper Y manufactured in a structure as mentioned above is bent inward on creases (a) and (b), and a sleeve-shaped body X is made up by sticking overlapping parts together by adhesion C. A part of the polyethylene film 3 exposed is shrunk by heating with a heater, enabling the front end 4a of the intermediate kraft paper 4 to be exposed. After that, a bottom part is formed by bending both sides on the front end of the sleeve-shaped body X in triangular shapes, and by making therewith the outer kraft paper 2 and the intermediate kraft paper 4 stuck together on the exposed part 5 by adhesion.;COPYRIGHT: (C)1993,JPO&Japio