Foldable bag and a method of manufacturing a foldable bag

1. A foldable bag, comprising

a front sheet and a back sheet circumferentially joined to each other in an unfolded condition wherein in the unfolded condition the bag has a bottom edge and an opposite top edge, and opposite side edges extending between the top edge and the bottom edge, wherein the bottom edge includes an inner bottom edge portion and outer bottom edge portions located at opposite sides of the inner bottom edge portion and extending up to the respective side edges, and wherein the bottom edge and opposing side edges join the front sheet directly to the back sheet and to define a cavity for fluid, so that the entirety of the back sheet is directly overlying the front sheet throughout the cavity;

and wherein in a folded condition in which the bag has a reversed T-shape including a bottom and an upward portion extending upwardly from the bottom, wherein

in the folded condition of the bag at the upward portion the side edges are inwardly creased between the front sheet and the back sheet such that they face to each other, and at the bottom the inner bottom edge portion extends substantially within the plane of the upward portion and each of the outer bottom edge portions extend substantially parallel above the inner bottom edge portion

whereupon filling of the bag in the folded condition returns the bag to the unfolded condition.

2. The foldable bag according to claim 1 , wherein the bottom of the bag in folded condition is substantially rectangular.

3. The foldable bag according to claim 1 , wherein in the unfolded condition the side edges extend substantially perpendicularly to the bottom edge and intersect the bottom edge at respective initial corners, wherein the initial corners face toward each other in the folded condition.

4. The foldable bag according to claim 1 , wherein

in the unfolded condition a first front sheet fold line and a first back sheet fold line extending perpendicularly to the side edges at a first distance from the bottom edge are defined on the front sheet and the back sheet, respectively, wherein the first front sheet fold line comprises an inner first front sheet fold line portion and outer first front sheet fold line portions extending at opposite sides of the inner first front sheet fold line portion and extending up to the respective side edges, whereas the first back sheet fold line comprises an inner first back sheet fold line portion and outer first back sheet fold line portions extending at opposite sides of the inner first back sheet fold line portion and extending up to the respective side edges, and wherein a second front sheet fold line and a second back sheet fold line extending perpendicularly to the side edges at substantially twice the first distance from the bottom edge are defined, wherein

the inner first front sheet fold line portion and the inner first back sheet fold line portion form opposite bottom side edges of the bottom of the bag in the folded condition, which inner first front and back sheet fold line portions extend substantially parallel to the plane of the upward portion of the reversed T-shape, and wherein

one of the outer first front sheet fold line portions together with one of the outer first back sheet fold line portions which are adjacent to each other in the unfolded condition, form a bottom side edge of the bottom of the bag in the folded condition extending perpendicularly to the plane of the upward portion.

5. The foldable bag according to claim 4 , wherein

in the unfolded condition of the bag each of the side edges comprises an upper side edge portion extending between the top edge and the second front and back sheet fold lines, an intermediate side edge portion extending between the second front and back sheet fold lines and the first front and back sheet fold lines, and a lower side edge portion extending between the first front and back sheet fold lines and the bottom edge, wherein

in the folded condition of the bag the upper side edge portions are present at the upward portion, and the intermediate side edge portion and the lower side edge portion of each of the side edge substantially lie onto each other at the bottom substantially in the plane of the upward portion.

6. The foldable bag according to claim 4 , wherein

the bag in the unfolded condition comprises a pair of substantially parallel fold lines on the front sheet and the back sheet at a predetermined distance of one of the side edges and a pair of substantially parallel fold lines on the front sheet and the back sheet at a predetermined distance of the opposite side edge, the fold lines extending substantially parallel to the side edges, wherein

in the folded condition of the bag both pairs of fold lines form side edges of the bag at the upward portion, whereas a bag portion extending between a pair of fold lines and the closest side edge thereof in the unfolded condition is folded inwardly at the upward portion in the folded condition, wherein

in the unfolded condition each of the fold lines comprises an intermediate fold line portion extending between the second front and back sheet fold lines and the first front and back sheet fold lines, and a lower fold line portion extending between the first front and back sheet fold lines and the bottom edge, wherein

in the folded condition the lower fold line portions form lower side edges of the bottom of the bag extending substantially perpendicularly to the plane of the upward portion and the intermediate fold line portions form upper side edges of the bottom of the bag extending substantially parallel above the lower side edges.

7. The foldable bag according to claim 6 , wherein the distance from the one side edge to the closest pair of fold lines is substantially the same as the distance from the opposite side edge to the pair of fold lines closest thereto.

8. The foldable bag according to claim 6 , wherein the length of the lower fold line portions is smaller than the length of the outer bottom edge portions.

9. The foldable bag according to claim 1 , wherein the bag in the unfolded condition only has the front sheet and the back sheet which are circumferentially joined to each other.

10. A foldable bag comprises a front sheet and a back sheet which are circumferentially joined to each other in an unfolded condition wherein the bag is disposed in a folded condition in which the bag has a reversed T-shape including a bottom and an upward portion extending upwardly from the bottom, and wherein in the folded condition of the bag, upward portion side edges are inwardly creased between the front sheet and the back sheet such that they face to each other, and wherein at the bottom, an inner bottom edge portion extends substantially within a plane of the upward portion and each of outer bottom edge portions extend substantially parallel above the inner bottom edge portion whereupon filling of the bag in the folded condition returns the bag to the unfolded condition.

11. A foldable bag comprises a front sheet and a back sheet which are circumferentially joined to each other in an unfolded condition wherein the bag is disposed in a folded condition wherein the bag includes a bottom edge and a top edge opposite to each other, and inwardly creased bag portions facing toward each other and extending between the bottom edge and the top edge, wherein each of the inwardly creased bag portions has an upper closed end located near the top edge and a lower closed end located near the bottom edge, wherein the upper closed end and the lower closed end are free ends, and wherein side edge portions are displaced from each other and located at a predetermined distance from the bottom edge at entrances of the inwardly creased portions away from each other whereupon filling of the bag in the folded condition returns the bag to the unfolded condition.