Leak proof bottom for a paperboard container

Claim 2

In combination with a thermoplastic coated paperboard blank adapted to be erected to form a heat sealed container, said blank having a body forming portion and a bottom forming portion, said bottom forming portion including two spaced apart gusset forming flaps having substantially aligned transverse edges and forming gusset points and gusset channels when said blank is erected, a cover flap foldably connected by a longitudinal fold line to at least one of said gusset forming flaps, and a tuck-in flap foldably connected by a longitudinal fold line to at least one of said gusset forming flaps, the improvement which comprises; a. the longitudinal length of at least the center portion of said tuck-in flap being approximately equal to one half the width of one of said gusset forming flaps and the remainder of said tuck-in flap disposed to entirely underlie said gusset forming flaps when said blank is erected; and b. a narrow band of thermoplastic material disposed upon the interior side of at least one of said bottom forming flaps so as to extend outwardly from said gusset points and along said gusset channel when a container is formed from said blank, said band of thermoplastic material having a thickness of at least approximately 5 mils and a longitudinal dimension less than the longitudinal length of said bottom forming flaps, the thickness and area of said band being such that, when a container is formed from said blank and said thermoplastic material is melted, it will not cover the entire area defined by said bottom forming flaps, whereby, when said blank is formed into a container, said thermoplastic material will seal at least the center portion of said gusset channels and at least the center portion of the tuck-in flap channel which is formed when said container is formed.

Claim 3

The blank of claim 1 wherein the longitudinal dimension of said band of thermoplastic material is at least approximately 0.125 inches.

Claim 4

The blank of claim 1 whErein said band of thermoplastic material is disposed upon said cover flap.

Claim 5

The paperboard blank of claim 3 wherein said band of thermoplastic material has a longitudinal dimension of at least approximately 0.125 inches.

Claim 6

The paperboard blank of claim 3 which further includes a band of thermoplastic material disposed upon said tuck-in flap.

Claim 7

The blank of claim 5 wherein said band of thermoplastic material has a longitudinal dimension of at least approximately 0.125 inches.

Claim 8

In combination with a thermoplastic coated paperboard blank adapted to be erected to form a square head sealed container, said blank having a body forming portion and a bottom forming portion, said bottom forming portion including two spaced apart gusset forming flaps having substantially aligned transverse edges and forming gusset points when said blank is erected, a cover flap foldably connected by a longitudinal fold line to at least one of said gusset forming flaps, said cover flap extending longitudinally beyond the transverse edges of said gusset forming flaps and a tuck-in flap foldably connected by a longitudinal fold line to at least one of said gusset forming flaps, the improvement which comprises: a. at least the center portion of the transverse edge of said tuck-in flap being substantially aligned with the transverse edges of said gusset forming flaps and the remainder of the edges of said tuck-in flap disposed to entirely underlie said gusset forming flaps when said blank is erected; and b. a narrow band of thermoplastic material disposed upon the interior side of at least the center portion of each of said bottom forming flaps, the outer edge of all of said bands being substantially transversely aligned, the outer edge of said bands disposed upon said gusset forming flaps being adjacent to the exposed transverse edge of said gusset forming flaps and the transverse length of each of said narrow bands of thermoplastic material being sufficient to heat seal said gusset points and the center portion of the transverse edge of the tuck-in flap when said blank is formed and sealed, said bands of thermoplastic material having a thickness of at least approximately 5 mils and having a longitudinal dimension less than the longitudinal length of said bottom forming flaps, the thickness and area of said bands being such that, when a container is formed from said blank and said thermoplastic material is melted, it will not cover the entire area defined by said bottom forming flaps, whereby, when said blank is formed into a container, said thermoplastic material will seal at least the center portion of said gusset channels and at least the center portion of the tuck-in flap channel which is formed when said container is formed.

Claim 9

In combination with a thermoplastic coated paperboard blank adapted to be erected to form a square head sealed container, said blank having a body forming portion and a bottom forming portion, said bottom forming portion including two spaced apart gusset forming flaps having substantially aligned transverse edges and forming gusset points when said blank is erected, a cover flap foldably connected by a longitudinal fold line to at least one of said gusset forming flaps, said cover flap extending longitudinally beyond the transverse edges of said gusset forming flaps and a tuck-in flap foldably connected by a longitudinal fold line to at least one of said gusset forming flaps, the improvement which comprises: a. at least the center portion of the transverse edge of said tuck-in flap being substantially aligned with the transverse edges of said gusset forming flaps and the remainder of the edges of said tuck-in flap disposed to entirely underlie said gusset forming flaps when said blank is erected; and b. a narrow band of thermoplastic material disposed upon the interior side of at least the center portion of each of said bottom forming flaps, the outer edge of all of said bands being substantially transversely aligned, the outer edge of said bands disposed upon said gusset forming flaps being adjacent to the exposed transverse edge of said gusset forming flaps and the transverse length of each of said narrow bands of thermoplastic material being sufficient to heat seal said gusset points and the center portion of the transverse edge of the tuck-in flap when said blank is formed and sealed, said bands of thermoplastic material having a thickness of at least approximately 5 mils and having a longitudinal dimension less than the longitudinal length of said bottom forming flaps, the thickness and area of said bands being such that, when a container is formed from said blank and said thermoplastic material is melted, it will not cover the entire area defined by said bottom forming flaps, whereby, when said blank is formed into a container, said thermoplastic material will seal at least the center portion of said gusset channels and at least the center portion of the tuck-in flap channel which is formed when said container is formed.

Claim 10

The blank of claim 7 wherein said tuck-in flap is notched.

Claim 11

The blank of claim 8 wherein said narrow band or thermoplastic material is at least approximately 0.125 inches wide.

Claim 12

The blank of claim 8 wherein said notch is rectangular and the length of said band is at least equal to the transverse width of said notch.

Claim 13

The blank of claim 10 wherein said narrow thermoplastic band extends entirely across said blank.

Claim 14

The blank of claim 10 wherein the melt index of said thermoplastic is in the range of 3.0 to 300.

Claim 15

In combination with a thermoplastic coated paperboard blank adapted to be erected to form a square heat sealed container, said blank having a body forming portion and a bottom forming portion, said bottom forming portion including two spaced apart gusset forming flaps having substantially aligned transverse edges and forming gusset points and gusset channels when said blank is erected, a cover flap foldably connected by a longitudinal fold line to at least one of said gusset forming flaps, said cover extending longitudinally beyond the transverse edges of said gusset flaps and a tuck-in flap foldably connected by a longitudinal fold line to at least onE of said gusset forming flaps, the improvement which comprises: a. the transverse edge of said tuck-in flap being substantially aligned with the transverse edges of said gusset forming flaps with the outer transverse edges of the tuck-in flap underlying said gusset forming flaps when said blank is erected; b. a narrow band of thermoplastic material disposed upon at least the center portion of each of said bottom flaps, all of said bands being substantially transversely aligned, the outer edge of said bands disposed upon said gusset forming flaps being adjacent to the exposed transverse edge of said gusset forming flaps and the transverse length of each of said narrow bands of thermoplastic material being sufficient to heat seal said gusset points and the center portion of the transverse edge of the tuck-in flap when said blank is formed and sealed, said band of thermoplastic material having a thickness of at least approximately 5 mils and a longitudinal dimension less than the longitudinal length of said bottom forming flaps, the thickness and area of said band being such that, when a container is formed from said blank and said thermoplastic material is melted, it will not cover the entire area defined by said bottom forming flaps, whereby, when said blank is formed into a container, said thermoplastic material will seal at least the center portion of said gusset channels and at least the center portion of the tuck-in flap which is formed when said container is formed.

Claim 16

In combination with a thermoplastic coated paperboard blank adapted to be erected to form a square heat sealed container, said blank having a body forming portion and a bottom forming portion, said bottom forming portion including two spaced apart gusset forming flaps having substantially aligned transverse edges and forming gusset points and gusset channels when said blank is erected, a cover flap foldably connected by a longitudinal fold line to at least one of said gusset forming flaps, said cover extending longitudinally beyond the transverse edges of said gusset flaps and a tuck-in flap foldably connected by a longitudinal fold line to at least onE of said gusset forming flaps, the improvement which comprises: a. the transverse edge of said tuck-in flap being substantially aligned with the transverse edges of said gusset forming flaps with the outer transverse edges of the tuck-in flap underlying said gusset forming flaps when said blank is erected; b. a narrow band of thermoplastic material disposed upon at least the center portion of each of said bottom flaps, all of said bands being substantially transversely aligned, the outer edge of said bands disposed upon said gusset forming flaps being adjacent to the exposed transverse edge of said gusset forming flaps and the transverse length of each of said narrow bands of thermoplastic material being sufficient to heat seal said gusset points and the center portion of the transverse edge of the tuck-in flap when said blank is formed and sealed, said band of thermoplastic material having a thickness of at least approximately 5 mils and a longitudinal dimension less than the longitudinal length of said bottom forming flaps, the thickness and area of said band being such that, when a container is formed from said blank and said thermoplastic material is melted, it will not cover the entire area defined by said bottom forming flaps, whereby, when said blank is formed into a container, said thermoplastic material will seal at least the center portion of said gusset channels and at least the center portion of the tuck-in flap which is formed when said container is formed.

Claim 17

The blank of claim 13 wherein the width of said narrow band of thermoplastic material is at least, approximately, 0.125 inches.

Claim 18

The blank of claim 14 wherein said thermoplastic material has a melt index in the range of, approximately, 3.0 to 300.

Claim 19

The blank of claim 15 wherein said narrow band of thermoplastic material extends substantially across the entire blank.