Rectangular-bottomed packaging bag, and method for manufacturing rectangular-bottomed packaging bag

A rectangular-bottomed packaging bag, which is a

• rectangular-bottomed packaging bag formed by folding a sheet material member, comprising:
• a rectangular shaped bottom;
• a front and a rear rising from two facing sides of the bottom;
• a pair of left and right sides connecting the front and the rear, and
• a bottom joining portion provided between the bottom and each of the front, the rear, and the pair of left and right sides,
• wherein
• the pair of left and right sides each includes:
• a first region positioned on the front side;
• a second region positioned on the rear side;
• a side joining portion joining the first region and the second region;
• and
• a first inclined joining portion inclined to a bottom side from the side joining portion toward the front, and joining the first region and a part of the sheet material member overlapping the first region in a direction of thickness of the first region, and a second inclined joining portion inclined to the bottom side from the side joining portion toward the rear, and joining the second region and a part of the sheet material member overlapping the second region in a direction of thickness of the second region,
• an end portion of each of the first inclined joining portion and the second inclined joining portion positioned on the bottom side is connected to the bottom joining portion,
• the rectangular-bottomed packaging bag further comprises a fixed sealing portion which joins the side joining portion and the first region or the second region in a state in which an entire region of only the side joining portion in an upright direction is folded towards the front side or the rear side and is disposed parallel to the first region or the second region, the fixed sealing portion being provided on each side of the pair of left and right sides,
• the bottom joining portion is formed on a circumferential edge of the bottom at a lower end of the rectangular-bottomed packaging bag, and is provided on an entire circumference of the rectangular-bottomed packaging bag,
• the bottom joining portion extends from lower ends of the front, the rear, the left side, and the right side on a same surface as the front, the rear, the left side, and the right side with a constant width,
• the entire region of the side joining portion in an upright direction is positioned on an outer surface of the rectangular-bottomed packaging bag,
• the fixed sealing portion joins only a portion of the bottom joining portion in the side joining portion and a portion of the bottom joining portion in the first region or the second region at a lower portion of the rectangular-bottomed packaging bag,
• in the fixed sealing portion, the sheet material member is a laminate in which
• an outermost layer thereof has heat fusibility,
• when the rectangular-bottomed packaging bag is filled with contents, the side joining portion is closed at the upper portion of the rectangular-bottomed packaging bag in a state in which it is sandwiched between the first region and the second region, and
• other than the upper portion and the lower portion of the rectangular-bottomed packaging bag, the side joining portion is not joined to the first region or the second region.