| 摘要 |
PURPOSE:To form sealed portion having very high resistance to shock breakage by cooling the sealed portion after heating under a specific condition in the manufacture of a bag by band sealing. CONSTITUTION:The sealing portion of a polyethylene film is melted and bonded by a heating bar 3, and the sealed portion is cooled in a freely expandible state by air blowing. In the temperature lowering process of the sealed portion, no forcible deformation occurs in the sealed portion, and the ratio of the length R1 of the sealed portion to the width R0 of the heating bar, R1/R2, in the cross section of the sealed portion is reduced and at the same time the ratio the thickness R2 of the sealed portion to the sum of the thickness D1 of one film to form a bag and the thickness D2 of the other film, R2/(D1+D2), is increased. The sealed portion having very high resistance to shock breakage can thus be formed. When cooling the sealed portion without causing forcible deformation by a cooling bar, the R2/(D1+D2) is more increased, no trouble, e.g., concentration of stress even when encountered with shock breakage, takes place in the sealed portion. |
