This invention relates to a bag, and more particularly to a packaging bag used for containing essentially grain, cement, etc. with preferable mechanical strength and air permeability.
As a bag for packaging rice, grain or the like, there is employed a bag of synthetic resin sheet perforated with a number of fine pores on the entire surface instead of a burlap bag. Since the synthetic resin sheet of the bag incorporates high surface smoothness, the bags are dangerously apt to collapse when the bags filling contents are stacked, to slide down from holding arms when they are carried in the arms, and to gradually increase its small crack due to its internal pressure of the content if the bag is once scratched to cause the small crack and to fail to safely contain the content. Further, the fragment of the bag is inclined to break down at its initial handling time after filling content in the bag, and broken paper is mixed with the content to thereby contaminate the content and thus cause a problem.