Carton bottom closure

1. A carton blank comprising:

first, second, third and fourth side panels, each having a top edge and a bottom edge;

a top flap foldably connected to the top edge of at least one of the first side panel, the second side panel, the third side panel, or the fourth side panel;

a major bottom flap foldably connected to the bottom edge of each of the first and third side panels;

a minor bottom flap foldably connected to the bottom edge of each of the second and fourth side panels; and

each major bottom flap including a longitudinal exterior edge at which a closure feature is located, the longitudinal exterior edge extending substantially parallel to the bottom edge;

each closure feature comprising an open aperture formed by a first edge extending from the longitudinal exterior edge to a longitudinal interior edge, a notch recess, a projection, and an oblique edge extending from the projection to the longitudinal exterior edge;

the projection being defined by an edge which extends a first distance from the oblique edge in a first direction substantially parallel to the bottom edge, then in a second direction toward the bottom edge, then in a third direction to the notch recess, the third direction being substantially parallel to the first direction;

the closure features being engageable when a carton is erected from the blank, thereby forming with the minor bottom flaps a closure for the bottom of the carton.

2. The carton blank of claim 1 , wherein the notch recess of each closure feature is engageable with the projection of the other closure feature.

3. The carton blank of claim 1 , wherein each major bottom flap includes an oblique fold line defining a hinged section.

4. The carton blank of claim 1 , wherein the first edge is oblique to the longitudinal exterior edge.

5. The carton blank of claim 1 , including a reinforcing blank secured to at least one of the side panels.

6. The carton blank of claim 5 , wherein the reinforcing blank overlies the first, second, third and fourth side panels.

7. A method of forming a carton from the carton blank of claim 1 ,

the method comprising the steps of:

attaching the first and fourth side panels together at their side edges;

opening the attached side panels up into a generally tubular form; and

engaging the closure features with each other, whereby the major and minor bottom flaps form a closure for the bottom of the carton.

8. The method of claim 7 , wherein the closure features are engaged by engaging the notch recess of each closure feature with the projection of the other closure feature.

9. The method of claim 7 , wherein each major bottom flap includes an oblique fold line defining a hinged section, and each hinged section is attached to the adjacent minor bottom flap before opening the attached side panels up into a generally tubular form.

10. The method of claim 7 , wherein opening the attached side panels up into a generally tubular form causes the closure features to engage each other.

11. A carton formed from the carton blank of claim 1 .

12. A carton which is the product of the method of claim 7 .

13. A carton blank for forming a carton, the blank comprising:

a sheet of material having a top edge, a bottom edge and two side edges;

at least first, second, third and fourth side panels defined by upper and lower longitudinal fold lines and a plurality of transverse fold lines;

a plurality of top flaps located at the tops of the side panels, between the upper longitudinal fold line and the top edge of the sheet;

a major bottom flap located at the bottom of at least two of the side panels, between the lower longitudinal fold line and the bottom edge of the sheet;

a minor bottom flap located at the bottom of at least another two of the side panels, between the lower longitudinal fold line and the bottom edge of the sheet;

each major bottom flap including a longitudinal exterior edge at which a closure feature is located, the longitudinal exterior edge extending substantially parallel to the lower longitudinal fold line;

each closure feature comprising an open aperture formed by a first edge extending from the longitudinal exterior edge to a longitudinal interior edge, a notch recess, a projection, and an oblique edge extending from the projection to the longitudinal exterior edge;

the projection being defined by an edge which extends a first distance from the oblique edge in a first direction substantially parallel to the longitudinal exterior edge, then in a second direction toward the lower longitudinal fold line, then in a third direction to the notch recess, the third direction being substantially parallel to the first direction; and

the closure features being interengageable in response to erection of the blank to form a bottom closure for the carton comprising the major bottom flaps and minor bottom flaps.

14. The carton blank of claim 13 , wherein the first edge is oblique to the longitudinal exterior edge.

15. The carton blank of claim 13 , including a hinged section on at least one major bottom flap, the hinged section being attachable to the adjacent minor bottom flap.

16. The carton blank of claim 15 , wherein the hinged section is defined by an oblique fold line in the major bottom flap.

17. A carton formed from the carton blank of claim 13 .